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Abstract: Indeterminate dendritic cell histiocytosis (IDCH) is a rare and poorly understood entity characterized by accumulation of CD1a+/S100+ histiocytes (as Langerhans cell histiocytosis [LCH]) but with reduced-absent expression of Langerin/CD207. We assembled 43 cases of IDCH (defined by CD1a+/CD207<20% immunophenotypic profile) examining the clinical, pathologic, and molecular landscape. Median age at presentation was 70 years (interquartile range, 44-80) with cutaneous (31/43; 72%) and nodal (11/43; 26%) involvement predominating. Eighteen (42%) individuals had an associated nonhistiocytic hematopoietic neoplasm ("secondary" IDCH) whereas 7 of 43 (16%) had a concurrent non-IDCH histiocytosis ("mixed" histiocytosis). Most cases exhibited morphology indistinguishable from LCH but with a CD1c+/CSF1R(CD115)- phenotype, mirroring the signature of normal indeterminate cells and conventional DC type 2. Mutational analysis revealed frequent KRAS (13/32; 41%) and BRAF p.V600E (11/36, 31%) mutations that were nearly mutually exclusive. RNA-sequencing analysis uncovered ETV3::NCOA2 fusion in 6 other patients presenting as a sole genetic alteration without any other concurrent histiocytic or hematopoietic neoplasm. BRAF and MAP2K1 alterations were significantly associated with partial/retained (1%-20%) Langerin expression (P = .005) and mixed histiocytosis (P = .002). Remarkably, myeloid alterations (DNMT3A, TET2, and SRSF2) co-occurred in IDCH tissues of several individuals. Paired sequencing of IDCH and concurrent non-IDCH hematopoietic neoplasm in 4 individuals revealed shared mutations. Age at diagnosis and any nodal involvement at diagnosis predicted inferior overall survival, but BRAF/RAS pathway alterations did not affect outcome. These data have implications for the diagnostic evaluation, classification, and therapeutic management of IDCH., (Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution.)

A wide range of articles describe the role of different probiotics in the prevention or treatment of various diseases. However, currently, the focus is shifting from whole microorganisms to their easier-to-define components that can confer similar or stronger benefits on the host. Here, we aimed to describe polysaccharide B.PAT, which is a surface antigen isolated from Bifidobacterium animalis ssp. animalis CCDM 218 and to understand the relationship between its structure and function. For this reason, we determined its glycerol phosphate-substituted structure, which consists of glucose, galactose, and rhamnose residues creating the following repeating unit: To fully understand the role of glycerol phosphate substitution on the B.PAT function, we prepared the dephosphorylated counterpart (B.MAT) and tested their immunomodulatory properties. The results showed that the loss of glycerol phosphate increased the production of IL-6, IL-10, IL-12, and TNF-α in bone marrow dendritic cells alone and after treatment with Lacticaseibacillus rhamnosus GG. Further studies indicated that dephosphorylation can enhance B.PAT properties to suppress IL-1β-induced inflammatory response in Caco-2 and HT-29 cells. Thus, we suggest that further investigation of B.PAT and B.MAT may reveal distinct functionalities that can be exploited in the treatment of various diseases and may constitute an alternative to probiotics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

During the birch pollen season an enhanced incidence of virus infections is noticed, raising the question whether pollen can affect anti-viral responses independent of allergic reactions. We previously showed that birch pollen-treatment of monocyte-derived dendritic cells (moDC) enhances human cytomegalovirus (HCMV) infection. Here we addressed how in moDC the relatively weak pollen response can affect the comparably strong response to HCMV. To this end, moDC were stimulated with aqueous birch pollen extract (APE), HCMV, and APE with HCMV, and transcriptomic signatures were determined after 6 and 24 h of incubation. Infection was monitored upon exposure of moDC to GFP expressing HCMV by flow cytometric analysis of GFP expressing cells. Principle component analysis of RNA sequencing data revealed close clustering of mock and APE treated moDC, whereas HCMV as well as APE with HCMV treated moDC clustered separately after 6 and 24 h of incubation, respectively. Communally induced genes were detected in APE, HCMV and APE with HCMV treated moDC. In APE with HCMV treated moDC, the comparably weak APE induced signatures were maintained after HCMV exposure. In particular, NF-κB/RELA and PI3K/AKT/MAPK signaling were altered upon APE with HCMV exposure. Earlier, we discovered that NF-κB inhibition alleviated APE induced enhancement of HCMV infection. Here we additionally found that impairment of PI3K signaling reduced HCMV infection in HCMV and APE with HCMV treated moDC. APE treated moDC that were exposed to HCMV show a unique host gene signature, which to a large extent is regulated by NF-κB activation and PI3K/AKT/MAPK signaling., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Plasmacytoid dendritic cells (pDCs) are a distinct subset of DCs involved in immune regulation and antiviral immune responses. Recent studies have elucidated the metabolic profile of pDCs and reported that perturbations in amino acid metabolism can modulate their immune functions. Glycolipid metabolism is suggested to be highly active in pDCs; however, its significance remains unclear. In this study, bulk RNA-sequencing analysis confirmed the known pDC-marker expressions, including interleukin (IL)-3R (CD123), BDCA-2 (CD303), BDCA-4 (CD304), and toll-like receptor 9, compared with that of myeloid DCs (mDCs). Among the differentially expressed genes, UDP-glucose-ceramide glucosyltransferase (UGCG) expression was significantly upregulated in pDCs than in mDCs. Moreover, pDC-specific UGCG expression was observed at both the mRNA and protein levels in pDCs and pDC-like cell lines, including CAL-1 and PMDC05 cell lines. Pharmacological or clustered regularly interspaced palindromic repeat (CRISPR)/CRISPR-associated protein 9-mediated genetic inhibition of UGCG did not affect the pDC phenotype as evidenced by the persistent expression of IL-3R and BDCA-2 in pDC-like cell lines. However, UGCG knockout resulted in reduced type I interferon production in pDCs upon CpG activation. In addition, UGCG-knockout pDC-like cell lines exhibited reduced transduction by vesicular stomatitis virus-G pseudo-typed lentiviral vectors, suggesting that low UGCG expression hinders infectivity. Collectively, our findings suggest that pDC-specific UGCG expression is critical for cytokine production and antiviral immune responses in pDCs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Biomaterials can act as pro- or anti-inflammatory agents. However, effects of biomaterials crystallinity on immune responses are poorly understood. We demonstrate that the adjuvant-like behaviour of covalent organic framework (COF) biomaterial is dependent on its crystallinity. COF crystallinity is inversely correlated with the activation of mouse and human dendritic cells (DC), but with antigen presentation by mouse DCs only. Amorphous COFs upregulates NFkB, TNF, and RIG-I signalling pathways, as well as the chemotaxis-associated gene Unc5c, when compared to crystalline COFs. Meanwhile, Unc5c inhibition disrupts the correlation between crystallinity and DC activation. Furthermore, COFs with the lowest crystallinity admixed with chicken ovalbumin (OVA) antigen prevent OVA-expressing B16F10 tumour growth in 60% of mice, with this protection associated with the induction of antigen-specific, pro-inflammatory T cell. The lowest crystalline COFs admixed with TRP2 antigen can also prevent non-immunogenic YUMM1.1 tumour growth in 50% of mice. These findings demonstrate that the crystallinity of biomaterials is an important aspect to consider when designing immunotherapy for pro- or anti-inflammatory applications., Competing Interests: Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Background: The physiological relevance of cell-to-cell communication mediated by small extracellular vesicle-encapsulated microRNAs (sEV-miRNAs) remains debated because of the limiting representativity of specific miRNAs within the extracellular pool. We hypothesize that sEV-miRNA non-canonical function consisting of the stimulation of Toll-like receptor 7 (TLR7) may rely on a global shift of the sEV cargo rather than on the induction of one or few specific miRNAs. Psoriasis represents an ideal model to test such hypothesis as it is driven by overt activation of TLR7-expressing plasmacytoid dendritic cells (pDCs) following keratinocyte damage., Methods: To mimic the onset of psoriasis, keratinocytes were treated with a cocktail of psoriatic cytokines or UV-irradiated. SmallRNA sequencing was performed on sEVs released by healthy and UV-treated keratinocytes. sEV-miRNAs were analyzed for nucleotide composition as well as for the presence of putative TLR7-binding triplets. Primary human pDCs where stimulated with sEVs +/- inhibitors of TLR7 (Enpatoran), of sEV release (GW4869 + manumycin) and of TLR7-mediated pDC activation (anti-BDCA-2 antibody). Secretion of type I IFNs and activation of CD8 + T cells were used as readouts. qPCR on psoriatic and healthy skin biopsies was conducted to identify induced miRNAs., Results: sEV-miRNAs released by damaged keratinocytes revealed a significantly higher content of TLR7-activating sequences than healthy cells. As expected, differential expression analysis confirmed the presence of miRNAs upregulated in psoriatic skin, including miR203a. More importantly, 76.5% of induced miRNAs possessed TLR7-binding features and among these we could detect several previously demonstrated TLR7 ligands. In accordance with this in silico analysis, sEVs from damaged keratinocytes recapitulated key events of psoriatic pathogenesis by triggering pDCs to release type I interferon and activate cytotoxic CD8 + T cells in a TLR7- and sEV-dependent manner., Discussion: Our results demonstrate that miR203a is just one paradigmatic TLR7-activating miRNA among the hundreds released by UV-irradiated keratinocytes, which altogether trigger pDC activation in psoriatic conditions. This represents the first evidence that cell damage shifts the miRNA content of sEVs towards a TLR7-activating cargo capable to propagate inflammation and immunity, offering strong support to the physiological role of systemic miRNA-based cell-to-cell communication., (© 2024. The Author(s).)

Dendritic cells (DCs) are crucial in cancer immunity, because they activate cytotoxic T cells by presenting tumor antigens. Recently, oncolytic virus therapy has been recognized as a systemic immune stimulator. We previously developed a telomerase-specific oncolytic adenovirus (OBP-301) and a p53-armed OBP-301 (OBP-702), demonstrating that these viruses strongly activate systemic antitumor immunity. However, their effects on DCs remained unclear. In the present study, the aim was to elucidate the mechanisms of DC activation by OBP-702, focusing particularly on tumor-derived exosomes. Exosomes (Exo53, Exo301, or Exo702) were isolated from conditioned media of human or murine pancreatic cancer cell lines (Panc-1, MiaPaCa-2, and PAN02) after treatment with Ad-p53, OBP-301, or OBP-702. Exo702 derived from Panc-1 and MiaPaCa-2 cells significantly upregulated CD86, CD80, CD83 (markers of DC maturation), and IFN-γ in DCs in vitro. Similarly, Exo702 derived from PAN02 cells upregulated CD86 and IFN-γ in bone marrow-derived DCs in a bilateral PAN02 subcutaneous tumor model. This DC maturation was inhibited by GW4869, an inhibitor of exosome release, and anti-CD63, an antibody targeting the exosome marker. Intratumoral injection of OBP-702 into PAN02 subcutaneous tumors significantly increased the presence of mature DCs and CD8-positive T cells in draining lymph nodes, leading to long-lasting antitumor effects through the durable activation of systemic antitumor immunity. In conclusion, tumor-derived exosomes play a significant role in DC maturation following OBP-702 treatment and are critical for the systemic activation of antitumor immunity, leading to the abscopal effect., (© 2024. The Author(s).)

The identification of adjuvants to improve vaccination efficacy is a major unmet need. One approach is to augment the functionality of dendritic cells (DCs) by using Toll-like receptor-9 (TLR9) agonists such as cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs) as adjuvants. Another approach is adjuvant selection based on production of bioactive interleukin-12 (IL-12). We report a D-peptide isomer, designated D-15800, that induces monocyte differentiation to the DC phenotype in vitro and more effectively stimulates IL-12p70 production upon T cell receptor (TCR) activation than the L-isomer. In the absence of TCR activation and either IL-12p70 or interleukin-2 production, only D-15800 activates CD4 + T and natural killer cells. In the presence of CpG ODN, D-15800 synergistically enhances production of interferon-alpha (IFN-α). Taken together with its biostability in human serum and depot retention upon injection, co-delivery of D-15800 with TLR9 agonists could serve to improve vaccine efficacy., (© 2024. The Author(s).)

Dendritic cells (DC) are specialized mononuclear phagocytes that link innate and adaptive immunity. They comprise two principal subsets: plasmacytoid DC (pDC) and conventional DC (cDC). Understanding the generation, differentiation, and migration of cDC is critical for immune homeostasis. Through human in vivo deuterium-glucose labeling, we observed the rapid appearance of AXL+ Siglec6+ DC (ASDC) in the bloodstream. ASDC circulate for ∼2.16 days, while cDC1 and DC2 circulate for ∼1.32 and ∼2.20 days, respectively, upon release from the bone marrow. Interestingly, DC3, a cDC subset that shares several similarities with monocytes, exhibits a labeling profile closely resembling that of DC2. In a human in vivo model of cutaneous inflammation, ASDC were recruited to the inflammatory site, displaying a distinctive effector signature. Taken together, these results quantify the ephemeral circulating lifespan of human cDC and propose functions of cDC and their precursors that are rapidly recruited to sites of inflammation., (© 2024 Lubin et al.)

PDZ (PSD-95 [postsynaptic density protein 95]/Dlg [Discs large]/ZO-1 [zonula occludens-1]) domain-containing proteins constitute a large family of scaffolds involved in a wide range of cellular tasks and are mainly studied in polarity functions. Diverse host PDZ proteins can be targeted by viral pathogens that express proteins containing PDZ-binding motifs (PDZbms). Previously, we have identified host PDZ-based interactions with the SARS-CoV-2 E protein (2E) in human monocytes. Here, we deepen the study of these interactions by docking and molecular dynamics analyses to identify the most favorable PDZ-PDZbm interaction of 7 host PDZ proteins with the PDZbm of 2E. In addition, we analyzed changes in the expression of 3 of the PDZ proteins identified as 2E interactors in monocytes (syntenin, ZO-2, and interleukin-16), in human monocyte-derived macrophages and in dendritic cells upon stimulation. Our results suggest that these PDZ proteins may have important functions in professional antigen-presenting cells, and their targeting by the PDZbm of 2E, a central virulence determinant of SARS-CoV-2, supports the hypothesis that such PDZ-dependent interaction in immune cells may constitute a viral evasion mechanism. An inhibitor design based on the PDZbm of 2E in the development of drugs against a variety of diseases is discussed., Competing Interests: Conflicts of interest. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for Leukocyte Biology.)

The metabolic profile of dendritic cells (DCs) shapes their phenotype and functions. The carboxylesterase 1 (CES1) enzyme is highly expressed in mononuclear myeloid cells; however, its exact role in DCs is elusive. We used a CES1 inhibitor (WWL113) and genetic overexpression to explore the role of CES1 in DC differentiation in inflammatory models. CES1 expression was analyzed during CD14+ monocytes differentiation to DCs (MoDCs) using quantitative polymerase chain reaction. A CES1 inhibitor (WWL113) was applied during MoDC differentiation. Surface markers, secreted cytokines, lactic acid production, and phagocytic and T cell polarization capacity were analyzed. The transcriptomic and metabolic profiles were assessed with RNA sequencing and mass spectrometry, respectively. Cellular respiration was assessed using seahorse respirometry. Transgenic mice were used to assess the effect of CES1 overexpression in DCs in inflammatory models. CES1 expression peaked early during MoDC differentiation. Pharmacological inhibition of CES1 led to higher expression of CD209, CD86 and MHCII. WWL113 treated MoDCs secreted higher quantities of interleukin (IL)-6, IL-8, tumor necrosis factor, and IL-10 and demonstrated stronger phagocytic ability and a higher capacity to polarize T helper 17 differentiation in an autologous DC-T cell coculture model. Transcriptomic profiling revealed enrichment of multiple inflammatory and metabolic pathways. Functional metabolic analysis showed impaired maximal mitochondrial respiration capacity, increased lactate production, and decreased intracellular amino acids and tricarboxylic acid cycle intermediates. Transgenic human CES1 overexpression in murine DCs generated a less inflammatory phenotype and increased resistance to T cell-mediated colitis. In conclusion, CES1 inhibition directs DC differentiation toward a more inflammatory phenotype that shows a stronger phagocytic capacity and supports T helper 17 skewing. This is associated with a disrupted mitochondrial respiration and amino acid depletion., Competing Interests: Conflict of interest statement: W.J.d.J. is co-founder and share holder of AIBiomics B.V., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for Leukocyte Biology.)

Sialic acids at the cell surface of dendritic cells (DCs) play an important immunomodulatory role, and their manipulation enhances DC maturation, leading to heightened T cell activation. Particularly, at the molecular level, the increased stability of surface MHC-I molecules in monocyte-derived DCs (MoDCs) underpins an improved DC: T cell interaction. In this study, we focused on the impact of sialic acid remodelling by treatment with Clostridium perfringens sialidase on MoDCs' phenotypic and functional characteristics. Our investigation juxtaposes this novel approach with the conventional cytokine-based maturation regimen commonly employed in clinical settings.Notably, C. perfringens sialidase remarkably increased MHC-I levels compared to other sialidases having different specificities, supporting the idea that higher MHC-I is due to the cleavage of specific sialoglycans on cell surface proteins. Sialidase treatment induced rapid elevated surface expression of MHC-I, MHC-II and CD40 within an hour, a response not fully replicated by 48 h cytokine cocktail treatment. These increases were also observable 48 h post sialidase treatment. While CD86 and PD-L1 showed significant increases after 48 h of cytokine maturation, 48 h post sialidase treatment showed a higher increase in CD86 and shorter increase in PD-L1. CCR-7 expression was significantly increased 48 h after sialidase treatment but not significantly affected by cytokine maturation. Both treatments promoted higher secretion of the IL-12 cytokine. However, the cytokine cocktail induced a more pronounced IL-12 production. SNA lectin staining analysis demonstrated that the sialic acid profile is significantly altered by sialidase treatment, but not by the cytokine cocktail, which causes only slight sialic acid upregulation. Notably, the lipid-presenting molecules CD1a, CD1b and CD1c remained unaffected by sialidase treatment in MoDCs, a finding also further supported by experiments performed on C1R cells. Inhibition of endogenous sialidases Neu1 and Neu3 during MoDC differentiation did not affect surface MHC-I expression and cytokine secretion. Yet, sialidase activity in MoDCs was minimal, suggesting that sialidase inhibition does not significantly alter MHC-I-related functions. Our study highlights the unique maturation profile induced by sialic acid manipulation in MoDCs. These findings provide insights into the potential of sialic acid manipulation as a rapid immunomodulatory strategy, offering promising avenues for targeted interventions in inflammatory contexts., (© 2024. The Author(s).)

Patients with metastatic brain melanomas (MBM) experience shorter-lasting survival than patients with extracranial metastases, and this is associated with a higher fraction of dysfunctional CD8 T cells. The goal of this study was to understand the underlying cause of T cell dysfunction in MBM. To accomplish this, we compared murine B16 melanomas implanted intracranially (IC) or subcutaneously (SC). CD8 T cell activation was not altered, but representation in IC tumors was lower. Transferred activated or naïve CD8 T cells accumulated in similar numbers in both tumors, suggesting that the vasculature does not differentially impair T cell presence. Surprisingly, we found no evidence for T cell activation in draining lymph nodes of SC or IC tumor-bearing mice, consistent with the fact that dendritic cells (DC) that had acquired tumor antigen showed an immature phenotype. Instead, T cell activation occurred within both tumors, where the majority of tumor antigen + myeloid cells were found. While, the numbers of intratumoral DC were comparable, those in IC tumors acquired less tumor antigen, and were alternatively matured based on upregulation of MHCII without upregulation of CD86. Additionally, in IC tumors, the largest population of tumor antigen + myeloid cells were microglia. However, their presence did not influence either antigen acquisition or the phenotype of other myeloid cell populations. Overall, our data suggest that diminished representation of CD8 T cells in IC tumors is a consequence of alternatively matured DC and/or microglia that induce distinctly activated T cells, which ultimately fail to continue to accumulate inside the tumor., (© 2024. The Author(s).)

Aim: Ergostatrien-3β-ol (EK100) is a bioactive compound found in the fruiting bodies and mycelia of Antrodia cinnamomea and has anti-inflammatory and immunomodulatory properties. This study aims to evaluate the potential of EK100 as a treatment for Sjögren's syndrome (SS)., Methods: We employed a spontaneous SS model in non-obese diabetic (NOD)/Ltj mice to assess the therapeutic potential of EK100. The effects of EK100 were evaluated based on stimulated salivary flow rates, sialadenitis, expression of inflammatory cytokines in salivary glands, and profiles of T cell subsets in the spleen. Additionally, in vitro experiments were conducted to assess the impact of EK100 on Th17 cell differentiation and dendritic cell (DC) maturation., Results: EK100 treatment significantly increased salivary flow rates, suppressed lymphocyte infiltration, and decreased the concentrations of anti-SSA/Ro and anti-SSB/La autoantibodies. EK100 also downregulated the expression of various inflammatory cytokines in the salivary glands and reduced the populations of Th1 and Th17 cells in the spleens of NOD/Ltj mice. In vitro experiments confirmed that EK100 inhibited the differentiation of Th17 cells and the maturation of DCs., Conclusion: Our findings suggest that EK100 may offer a promising therapeutic avenue for the treatment of SS by modulating the interaction between Th17 cells and DCs., (© 2024 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.)

Kirsten rat sarcoma virus (KRAS)-G12C inhibition causes remodeling of the lung tumor immune microenvironment and synergistic responses to anti-PD-1 treatment, but only in T cell infiltrated tumors. To investigate mechanisms that restrain combination immunotherapy sensitivity in immune-excluded tumors, we used imaging mass cytometry to explore cellular distribution in an immune-evasive KRAS mutant lung cancer model. Cellular spatial pattern characterization revealed a community where CD4 + and CD8 + T cells and dendritic cells were gathered, suggesting localized T cell activation. KRAS-G12C inhibition led to increased PD-1 expression, proliferation, and cytotoxicity of CD8 + T cells, and CXCL9 expression by dendritic cells, indicating an effector response. However, suppressive regulatory T cells (T regs ) were also found in frequent contact with effector T cells within this community. Lung adenocarcinoma clinical samples showed similar communities. Depleting T regs led to enhanced tumor control in combination with anti-PD-1 and KRAS-G12C inhibitor. Combining T reg depletion with KRAS inhibition shows therapeutic potential for increasing antitumoral immune responses.

The healing process of chronic wounds often progresses slowly and is fraught with challenges, imposing increasing economic burdens and physical suffering on patients. Managing persistent wound inflammation and stimulating angiogenesis are crucial elements in promoting wound healing. Plants have been playing a key role in traditional medicine, and their abundant bioactive components continually inspire the development and innovation of new drugs. Isoliquiritigenin (ISL), a flavonoid compound derived from licorice roots known as chalcone, has demonstrated multifaceted pharmacological potential. However, its effects on diabetic wounds and the detailed mechanisms remain to be investigated. Through in-depth exploration using network pharmacology, we successfully predicted potential therapeutic targets of ISL for ischemic diseases. The revealed mechanisms primarily focused on the critical pathway of efferocytosis. Subsequent in vivo experiments demonstrated that ISL significantly enhanced the efferocytosis of dendritic cells (DC), improving the functional behaviors of endothelial cells. Further research indicated that ISL promoted DC efferocytosis by regulating SLC7A11-mediated glycolysis. Notably, the overexpression of SLC7A11 diminished the positive effects of ISL, suggesting a potential antagonistic role of SLC7A11 in the regulatory process. In the wounds of diabetic mice, we observed that ISL accelerated DC efferocytosis and angiogenesis, resulting in faster wound closure and better tissue repair. In summary, this study not only demonstrates the broad potential of ISL in managing diabetic wounds but also delves deeply into its mechanisms, laying a solid theoretical foundation for future clinical applications., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Weijie Chen reports financial support was provided by Taizhou Science and Technology Bureau. Xin Zheng reports financial support was provided by Medical Science and Technology Project of Zhejiang Province. Xin Zheng reports financial support was provided by Zhejiang Administration Bureau of Traditional Chinese Medicine. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Autoactivation of lineage-determining transcription factors mediates bistable expression, generating distinct cell phenotypes essential for complex body plans. Classical type 1 dendritic cell (cDC1) and type 2 dendritic cell (cDC2) subsets provide nonredundant functions for defense against distinct immune challenges. Interferon regulatory factor 8 (IRF8), the cDC1 lineage-determining transcription factor, undergoes autoactivation in cDC1 progenitors to establish cDC1 identity, yet its expression is downregulated during cDC2 differentiation by an unknown mechanism. This study reveals that the Irf8 +32-kb enhancer, responsible for IRF8 autoactivation, is naturally suboptimized with low-affinity IRF8 binding sites. Introducing multiple high-affinity IRF8 sites into the Irf8 +32-kb enhancer causes a gain-of-function effect, leading to erroneous IRF8 autoactivation in specified cDC2 progenitors, redirecting them toward cDC1 and a novel hybrid DC subset with mixed-lineage phenotypes. Further, this also causes a loss-of-function effect, reducing Irf8 expression in cDC1s. These developmental alterations critically impair both cDC1-dependent and cDC2-dependent arms of immunity. Collectively, our findings underscore the significance of enhancer suboptimization in the developmental segregation of cDCs required for normal immune function., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Sticholysin II (StII), a pore-forming toxin from the marine anemone Stichodactyla helianthus, enhances an antigen-specific cytotoxic T lymphocyte (CTL) response when co-encapsulated in liposomes with a model antigen. This capacity does not depend exclusively on its pore-forming activity and is partially supported by its ability to activate Toll-like receptor 4 (TLR4) in dendritic cells, presumably by interacting with this receptor or by triggering signaling cascades upon binding to lipid membrane. In order to investigate whether the lipid binding capacity of StII is required for immunomodulation, we designed a mutant in which the aromatic amino acids from the interfacial binding site Trp110, Tyr111 and Trp114 were substituted by Ala. In the present work, we demonstrated that StII3A keeps the secondary structure composition and global folding of StII, while it loses its lipid binding and permeabilization abilities. Despite this, StII3A upregulates dendritic cells maturation markers, enhances an antigen-specific effector CD8+ T cells response and confers antitumor protection in a preventive scenario in C57BL/6 mice. Our results indicate that a mechanism independent of its lipid binding ability is involved in the immunomodulatory capacity of StII, pointing to StII3A as a promising candidate to improve the reliability of the Sts-based vaccine platform., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Antiprogrammed death ligand 1 (PD-L1) therapy is a leading immunotherapy, but only some patients with solid cancers benefit. Overwhelming evidence has revealed that PD-L1 is expressed on various immune cells in the tumor microenvironment (TME), including macrophages, dendritic cells, and regulatory T cells, modulating tumor immunity and influencing tumor progression. PD-L1 can also be located on tumor cell membranes as well as in exosomes and cytoplasm. Accordingly, the dynamic expression and various forms of PD-L1 might explain the therapy's limited efficacy and resistance. Herein a systematic summary of the expression of PD-L1 on different immune cells and their regulatory mechanisms is provided to offer a solid foundation for future studies., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Hematopoiesis is driven by molecular mechanisms that induce differentiation and proliferation of hematopoietic stem cells and their progeny. This involves the activity of various transcription factors, such as members of the Hairy/Enhancer of Split (HES) family, and important roles for both HES1 and HES4 have been shown in normal and malignant hematopoiesis. Here, we investigated the role of HES6 in human hematopoiesis using in vitro and in vivo models. Using bulk and single-cell RNA-sequencing data, we show that HES6 is expressed during erythroid/megakaryocyte and plasmacytoid dendritic cell development, as well as in multipotent precursors and at specific stages of T- and B-cell development following pre-B-cell receptor and pre-T-cell receptor signaling, respectively. Consistently, knockdown of HES6 in cord blood-derived hematopoietic precursors in well-defined in vitro differentiation assays resulted in reduced differentiation of human hematopoietic precursors towards megakaryocytes, erythrocytes, plasmacytoid dendritic cells, B cells and T cells. In addition, HES6 knockdown hematopoietic stem and progenitor cells displayed reduced colony-forming unit capacity in vitro and impaired potential to reconstitute hematopoiesis in vivo in a competitive transplantation assay. We demonstrate that loss of HES6 expression has an impact on cell cycle progression during erythroid differentiation and provide evidence for potential downstream target genes that affect these perturbations. Thus, our study provides new insights into the role of HES6 in human hematopoiesis.

Prurigo nodularis (PN) is a chronic, inflammatory skin condition that disproportionately affects African Americans and features intensely pruritic, hyperkeratotic nodules on the extremities and trunk. PN is understudied compared with other inflammatory skin diseases, with the spatial organization of the cutaneous infiltrate in PN yet to be characterized. In this work, we employ spatial imaging mass cytometry to visualize PN lesional skin inflammation and architecture with single-cell resolution through an unbiased machine learning approach. PN lesional skin has increased expression of caspase 3, NF-kB, and phosphorylated signal transducer and activator of transcription 3 compared with healthy skin. Keratinocytes in lesional skin are subdivided into CD14+CD33+, CD11c+, CD63+, and caspase 3-positive innate subpopulations. CD14+ macrophage populations expressing phosphorylated extracellular signal-regulated kinase 1/2 correlate positively with patient-reported itch (P = .006). Hierarchical clustering reveals a cluster of patients with PN with greater atopy, increased NF-kB+ signal transducer and activator of transcription 3-positive phosphorylated extracellular signal-regulated kinase 1/2-positive monocyte-derived myeloid dendritic cells, and increased vimentin expression (P < .05). Neighborhood analysis finds interactions between CD14+ macrophages, CD3+ T cells, monocyte-derived myeloid dendritic cells, and keratinocytes expressing innate immune markers. These findings highlight phosphorylated extracellular signal-regulated kinase-positive CD14+ macrophages as contributors to itch and suggest an epithelial-immune axis in PN pathogenesis., (Copyright © 2024. Published by Elsevier Inc.)

Saccharomyces cerevisiae, a widely studied yeast known for its industrial applications, is increasingly recognized for its potential in immunomodulation. This study aimed to systematically analyze and compare the immune-modulating properties of various S. cerevisiae strains under controlled experimental conditions. Three essential signals crucial for immune response activation were evaluated to elucidate the immunological responses elicited by these strains, i.e., dendritic cells (DC) cytokine secretion profiles, maturation status, and T cell polarization. Analysis of DC cytokine secretion profiles and maturation status revealed that all tested yeast strains induced DC activation, characterized by significant IL-6 secretion and modest IL-10 induction, as well as upregulation of MHC II molecules. Additionally, strain-specific effects were observed, particularly, strain AJM109 and Y1383 uniquely enhanced CD86 and PD-L1 expression, respectively, suggesting differential impacts on DC co-stimulatory signaling. Furthermore, strain Y1383 showed a unique capacity to support Treg-mediated immune suppression, demonstrating its potential in immune tolerance induction. These findings underscore the complexity of S. cerevisiae-based immune modulation and emphasize the importance of standardized evaluation methods to distinguish their specific immunological effects., (© 2024. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

The major histocompatibility complex (MHC) class I molecules present peptide antigens to MHC class I-restricted CD8+ T lymphocytes to elicit an effective immune response. The conventional antigen-processing pathway for MHC-I presentation depends on proteasome-mediated peptide generation and peptide loading in the endoplasmic reticulum by members of the peptide loading complex. Recent discoveries in this field highlight the role of alternative MHC-I peptide loading and presentation pathways, one of them being autophagy. Autophagy is a cell-intrinsic degradative pathway that ensures cellular homoeostasis and plays critical roles in cellular immunity. In this review article, we discuss the role of autophagy in MHC class I-restricted antigen presentation, elucidating new findings on the crosstalk of autophagy and ER-mediated MHC-I peptide presentation, dendritic cell-mediated cross-presentation and also mechanisms governing immune evasion. A detailed molecular understanding of the key drivers of autophagy-mediated MHC-I modulation holds promising targets to devise effective measures to improve T cell immunotherapies., (© 2023 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals LLC.)

The intestinal lumen is rich in gut microbial metabolites that serve as signaling molecules for gut immune cells. G-protein-coupled receptors (GPCRs) sense metabolites and can act as key mediators that translate gut luminal signals into host immune responses. However, the impacts of gut microbe-GPCR interactions on human physiology have not been fully elucidated. Here, we show that GPR31, which is activated by the gut bacterial metabolite pyruvate, is specifically expressed on type 1 conventional dendritic cells (cDC1s) in the lamina propria of the human intestine. Using human induced pluripotent stem cell-derived cDC1s and a monolayer human gut organoid coculture system, we show that cDC1s extend their dendrites toward pyruvate on the luminal side, forming transepithelial dendrites (TED). Accordingly, GPR31 activation via pyruvate enhances the fundamental function of cDC1 by allowing efficient uptake of gut luminal antigens, such as dietary compounds and bacterial particles through TED formation. Our results highlight the role of GPCRs in tuning the human gut immune system according to local metabolic cues., Competing Interests: Competing interests statement:The authors declare no competing interest.

The stimulator of interferon genes (STING) pathway is crucial for tumor immunity, leading to the exploration of STING agonists as potential immunotherapy adjuvants. However, their clinical application faces obstacles including poor pharmacokinetics, transient activation, and an immunosuppressive tumor microenvironment (TME). Addressing these limitations, our study aims to develop an injectable silk fibroin hydrogel-based in situ vaccine. It incorporates a nanoscale STING agonist, an immunogenic cell death (ICD) inducer, and an immunomodulator to ensure their controlled and sustained release. cGAMP nanoparticles (cGAMPnps) with a core-shell structure ensure optimal delivery of cGAMP to dendritic cells (DCs), thereby activating the STING pathway and fostering DC maturation. ICD-associated damage-associated molecular patterns amplify and prolong STING activation via enhanced type I IFN and other inflammatory pathways, along with delayed degradation of cGAMP and STING. Furthermore, the STING-driven vascular normalization by cGAMPnps and ICD, in conjunction with immunomodulators like antiprogrammed cell death protein 1 antibody (anti-PD-1 Ab) or OX40 ligand (OX40L), effectively remodels the immunosuppressive TME. This in situ gel vaccine, when used independently or with surgery as neoadjuvant/adjuvant immunotherapy, enhances DC and CD8 + T-cell activation, suppressing tumor progression and recurrence across various immunologically cold tumor models. It revolutionizes the application of STING agonists in cancer immunotherapy, offering substantial promise for improving outcomes across a broad spectrum of malignancies.

Background: Cancer immunotherapy, particularly immune checkpoint inhibitors (ICBs) such as anti-PD-1 antibodies, has revolutionised cancer treatment, although response rates vary among patients. Previous studies have demonstrated that caerin 1.1 and 1.9, host-defence peptides from the Australian tree frog, enhance the effectiveness of anti-PD-1 and therapeutic vaccines in a murine TC-1 model by activating tumour-associated macrophages intratumorally., Methods: We employed a murine B16 melanoma model to investigate the therapeutic potential of caerin 1.1 and 1.9 in combination with anti-CD47 and a therapeutic vaccine (triple therapy, TT). Tumour growth of caerin-injected primary tumours and distant metastatic tumours was assessed, and survival analysis conducted. Single-cell RNA sequencing (scRNAseq) of CD45 + cells isolated from distant tumours was performed to elucidate changes in the tumour microenvironment induced by TT., Results: The TT treatment significantly reduced tumour volumes on the treated side compared to untreated and control groups, with notable effects observed by Day 21. Survival analysis indicated extended survival in mice receiving TT, both on the treated and distant sides. scRNAseq revealed a notable expansion of conventional type 1 dendritic cells (cDC1s) and CD4 + CD8 + T cells in the TT group. Tumour-associated macrophages in the TT group shifted toward a more immune-responsive M1 phenotype, with enhanced communication observed between cDC1s and CD8 + and CD4 + CD25 + T cells. Additionally, TT downregulated M2-like macrophage marker genes, particularly in MHCIIhi and tissue-resident macrophages, suppressing Cd68 and Arg1 expression across all macrophage types. Differential gene expression analysis highlighted pathway alterations, including upregulation of oxidative phosphorylation and MYC target V1 in Arg1 hi macrophages, and activation of pro-inflammatory pathways in MHCII hi and tissue-resident macrophages., Conclusion: Our findings suggest that caerin 1.1 and 1.9, combined with immunotherapy, effectively modulate the tumour microenvironment in primary and secondary tumours, leading to reduced tumour growth and enhanced systemic immunity. Further investigation into these mechanisms could pave the way for improved combination therapies in advanced melanoma treatment., (© 2024. The Author(s).)

Coupling size exclusion chromatography (SEC) with mass spectrometry-based proteomics enables investigating protein complexes, with degradomic profiling providing deeper insights into complex-associated proteolytic processing and retaining of cleavage products. This study aims to map protein complex formation upon inflammasome activation in bone marrow-derived dendritic cells (BMDCs) from gasdermin D-deficient mice, focusing on proteolytic enzymes and truncated proteins in higher molecular weight complexes. Cultured BMDCs were primed with LPS and subsequently treated with nigericin or Val-boroPro (VbP). SEC-fractionated proteins were TMT-labelled and analyzed via liquid chromatography-tandem mass spectrometry (LC-MS/MS). We identified 6862 proteins and 70 802 peptides, including 14 714 semi-tryptic peptides indicating elevated endogenous proteolytic processing. The sequence motif of numerous cleavage sites maps to caspase-like activity. Inflammasome activation was corroborated by elevated levels of apoptosis-associated speck-like protein containing a CARD (ASC) in higher molecular weight (MW) fractions and increased IL-1β levels in low MW fractions upon nigericin or VbP treatment. The majority of truncated cleavage products remained within their corresponding, higher MW protein complexes while caspase-specific cleavage products of Rho-associated protein kinase 1, gelsolin, and AP-2 complex subunit alpha-2 dissociated to lower MW fractions. SEC profiles identified 174 proteases, with cell surface proteases forming high MW complexes, including ADAMs and DPP4 but not MMP14. VbP treatment led to the accumulation of ISG15 in low MW fractions while RNA polymerase II coactivator p15 shifted to higher MW fractions. This study demonstrates that SEC-coupled proteomics and degradomic profiling offer unique insights into protein complex dynamics and proteolytic processes upon inflammasome activation.

Background: Individuals with a loss-of-function single-nucleotide polymorphism in the gene encoding PTPN22 have an increased risk for autoimmune diseases, and patients with cancer with such alleles may respond better to checkpoint blockade immunotherapy. Studies in PTPN22 knockout (KO) mice have established it as a negative regulator of T cell responses in cancer models. However, the role of PTPN22 in distinct immune cell compartments, such as dendritic cells (DCs), remains undefined., Methods: We developed a novel PTPN22 conditional KO (cKO) mouse model that enables specific deletion in CD11c + DCs by crossing to CD11c-Cre transgenic mice. Antitumor immunity was characterized using the B16.SIY and MC38.SIY cancer models and immune profiles of relevant tissues were evaluated by spectral flow cytometry. Antigen uptake, processing, and presentation, as well as DC proliferation to Flt3L, were characterized ex vivo., Results: Deletion of PTPN22 in DCs resulted in augmented antitumor immunity in multiple syngeneic tumor models. Tumor antigen-specific CD8 + T cells were increased in the tumor microenvironment (TME) of PTPN22 cKO mice and improved tumor control was CD8 + T cell-dependent. Augmented T cell priming was also detected at early time points in the draining lymph nodes, and these effects were correlated with an increased number of proliferating CD103 + DCs, also seen in the TME. In vitro studies revealed increased DC proliferation in response to Flt3L, as well as increased antigen processing and presentation. PTPN22 cKO mice bearing MC38 parental tumors showed combinatorial benefit with anti-PD-L1 therapy., Conclusions: Deletion of PTPN22 in DCs is sufficient to drive an augmented tumor antigen-specific T cell response, resulting in enhanced tumor control. PTPN22 negatively regulates DC proliferation and antigen processing and presentation. Our work argues that PTPN22 is an attractive therapeutic target for cancer immunotherapy and highlights the potential to modulate antitumor immunity through the manipulation of DC signaling., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Serotonergic neurons in the central nervous system control behavior and mood, but knowledge of the roles of serotonergic circuits in the regulation of immune homeostasis is limited. Here, we employ mouse genetics to investigate the functions of enteric serotonergic neurons in the control of immune responses and find that these circuits regulate IgA induction and boost host defense against oral, but not systemic Salmonella Typhimurium infection. Enteric serotonergic neurons promote gut-homing, retention and activation of intestinal plasmacytoid dendritic cells (pDC). Mechanistically, this neuro-immune crosstalk is achieved through a serotonin-5-HT receptor 7 (HTR7) signaling axis that ultimately facilitates the pDC-mediated differentiation of IgA + B cells from IgD + precursors in the gut. Single-cell RNA-seq data further reveal novel patterns of bidirectional communication between specific subsets of enteric neurons and lamina propria DC. Our findings thus reveal a close interplay between enteric serotonergic neurons and gut immune homeostasis that enhances mucosal defense., (© 2024. The Author(s).)

Objective: To observe the effects and mechanisms of Maresin2 on the function of DCs(Dendritic cells)., Method: The levels of IL-6, IL-12, TNF-α and IL-1β secreted by BMDCs (Bone marrow-derived Dendritic cells) after Maresin2 treatment were detected by ELISA. At the same time, the expressions of costimulatory molecules CD40 and CD86 on the surface, the ability of phagocytosis of ovalbumin(OVA) antigen, and antigen presentation function in BMDCs were analyzed by flow cytometry. Finally, MAPK and NF-κB pathway signaling phosphorylation in Maresin2-treated BMDCs were detected by western blot., Results: The secretion levels of IL-6, IL-12, TNF-α and IL-1β were significantly decreased in the Maresin2 treatment group after LPS treatment (P < 0.05). The expression levels of CD86 and CD40 were significantly decreased after Maresin2 treatment (P < 0.05). Maresin2 enhanced the phagocytosis ability of ovalbumin(OVA) (P < 0.05), but the ability of antigen presentation of BMDCs with the treatment of Maresin2 changed slightly (P > 0.05). Phosphorylation of p38, JNK, p65, ikka/β and ERK peaked at 15 min in the LPS group, while phosphorylation of p-p38 and p-ERK weakened 30 min and 60 min after treatment with Maresin2., Conclusions: Maresin2 inhibits inflammatory cytokine secretion but enhances phagocytosis via the MAPK/NF-κB pathway in BMDCs, which may contribute to negatively regulating inflammation., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Although the efficacy of trastuzumab deruxtecan (T-DXd) against HER2-positive gastric cancers (GCs) has driven its clinical application, the precise mechanisms governing its immunomodulatory role remain unclear. In this study, we examined the immune-related mechanisms of action of T-DXd in GC cells. T-DXd exhibited potent antitumor effects in GC cells across diverse HER2 expression levels by inducing DNA damage and apoptosis. Activation of the DNA damage response by T-DXd led to increased PD-L1 expression. RNA-Seq analysis revealed that T-DXd modulated immune-related pathways, resulting in the upregulation of genes associated with inflammation and IFN signaling. Importantly, T-DXd activated the cGAS-STING pathway, inducing an IFN-I response in HER2-positive GC cells. Furthermore, T-DXd activated dendritic cells via the cancer cell-intrinsic cGAS-STING-IFN axis and enhanced PBMC-mediated tumor cell killing by activating CD8 + T cells. These findings provide valuable insights into the role of the cytosolic DNA sensing pathway in the action of T-DXd and offer a compelling rationale for combining T-DXd with immune checkpoint blockade therapies in GC treatment., (© 2024. The Author(s).)

The lymph node paracortex, also known as the T-cell zone, consists of a network of fibroblastic reticular cells (FRCs) that secrete chemokines to induce T-cell and dendritic cell (DC) trafficking into the paracortex. To model the lymph node paracortex, we utilize multi-channel microfluidic devices to engineer a 3D lymph node stromal network from human cultured FRCs embedded in a collagen I-fibrin hydrogel. In the hydrogel, the FRCs self-assemble into an interconnected network, secrete the extracellular matrix proteins entactin, collagen IV, and fibronectin, as well as express an array of immune cell trafficking chemokines. Although the engineered FRC network did not secrete characteristic CCR7-ligand chemokines (i.e. CCL19 and CCL21), human primary TNF- α matured monocyte-derived DCs, CD45RA + T-cells, and CD45RA - T-cells migrate toward the lymph node stromal network to a greater extent than toward a blank hydrogel. Furthermore, the FRCs co-recruit DCs and antigen-specific T-cells into the lymph node stromal network. This engineered lymph node stromal network may help evaluate how human DCs and T-cells migrate into the lymph node paracortex via CCR7-independent mechanisms., (Creative Commons Attribution license.)

Dendritic cells (DCs) are crucial for initiating protective immune responses and have also been implicated in the generation and regulation of Foxp3 + regulatory T cells (Treg cells). Here, we show that in the lamina propria of the small intestine, the alternative NF-κB family member RelB is necessary for the differentiation of cryptopatch and isolated lymphoid follicle-associated DCs (CIA-DCs). Moreover, single-cell RNA sequencing reveals a RelB-dependent signature in migratory DCs in mesenteric lymph nodes favoring DC-Treg cell interaction including elevated expression and release of the chemokine CCL22 from RelB-deficient conventional DCs (cDCs). In line with the key role of CCL22 to facilitate DC-Treg cell interaction, RelB-deficient DCs have a selective advantage to interact with Treg cells in an antigen-specific manner. In addition, DC-specific RelB knockout animals show increased total Foxp3 + Treg cell numbers irrespective of inflammatory status. Consequently, DC-specific RelB knockout animals fail to mount protective Th2-dominated immune responses in the intestine after infection with Heligmosomoides polygyrus bakeri. Thus, RelB expression in cDCs acts as a rheostat to establish a tolerogenic set point that is maintained even during strong type 2 immune conditions and thereby is a key regulator of intestinal homeostasis., (© 2024. The Author(s).)

Neutrophil cationic proteins (NCPs) are a group of granule antimicrobial and inflammatory proteins released by activated neutrophils. These proteins primarily function via their positively charged structure, which facilitates interactions with bacterial membranes and the formation of immunogenic DNA complexes, thereby contributing to the initiation of wound repair in injured skin. After analyzing the structural properties of secreted neutrophil granule proteins, we identified OLFM4 as the only negatively charged molecule that interferes with NCP oligomerization. Through this interference, OLFM4 can inhibit neutrophil-mediated bacterial killing and DNA complex-dependent activation of Toll-like receptor 9 (TLR9) in plasmacytoid dendritic cells (pDCs) and neutrophils. While addition of exogenous OLFM4 blocks these processes, OLFM4 inhibition enhances neutrophil-dependent bacterial killing and DNA complex formation, ultimately leading to accelerated closure of skin wounds., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Whole tumor cell vaccines hold promise by presenting a broader spectrum of autologous-origin tumor antigens to combat postoperative recurrence and metastasis. However, challenges such as intractable adjuvant modification and obscure interactions with antigen-presenting cells in the postoperative microenvironment impede their translation into effective personalized immunotherapies. In this study, we propose cancer vaccines derived from manganese oxide-immobilized resected tumor cells, featuring whole tumor antigens and adjustable stiffness to modulate interactions with antigen-presenting cells in the postoperative microenvironment. These vaccines effectively stimulate dendritic cell phagocytosis and function through sequential stiffness-mediated mechanotransduction and interferon signaling. We evaluated their efficacy using an orthotopic triple-negative breast cancer mouse model and found that combining the vaccines with radiotherapy effectively inhibits postoperative tumor recurrence and metastasis. Our study underscores the potential of utilizing mechanotransduced adjuvants alongside directly inactivated whole-cell vaccines as a universal solution for preventing postoperative tumor recurrence.

Sirtuin 1 (SIRT1) is a class III histone deacetylase (HDAC3) that plays a crucial role in regulating the activation and differentiation of dendritic cells (DCs) as well as controlling the polarization and activation of T cells. Obesity, a chronic inflammatory condition, is characterized by the activation of immune cells in various tissues. We hypothesized that SIRT1 might influence the phenotype and functions of DCs through the Ido1 pathway, ultimately leading to the polarization towards pro-inflammatory T cells in obesity. In our study, we observed that SIRT1 activity was reduced in bone marrow-derived DCs (BMDCs) from obese animals. These BMDCs exhibited elevated oxidative phosphorylation (OXPHOS) and increased extracellular acidification rates (ECAR), along with enhanced expression of class II MHC, CD86, and CD40, and elevated secretion of IL-12p40, while the production of TGF-β was reduced. The kynurenine pathway activity was decreased in BMDCs from obese animals, particularly under SIRT1 inhibition. SIRT1 positively regulated the expression of Ido1 in DCs in a PPARγ-dependent manner. To support these findings, ATAC-seq analysis revealed that BMDCs from obese mice had differentially regulated open chromatin regions compared to those from lean mice, with reduced chromatin accessibility at the Sirt1 genomic locus in BMDCs from obese WT mice. Gene Ontology (GO) enrichment analysis indicated that BMDCs from obese animals had disrupted metabolic pathways, including those related to GTPase activity and insulin response. Differential expression analysis showed reduced levels of Pparg and Sirt1 in BMDCs from obese mice, which was challenged and confirmed using BMDCs from mice with conditional knockout of Sirt1 in dendritic cells (SIRT1∆). This study highlights that SIRT1 controls the metabolism and functions of DCs through modulation of the kynurenine pathway, with significant implications for obesity-related inflammation., (© 2024. The Author(s).)

Plexiform neurofibromas (PNFs) are benign nerve tumors driven by loss of the NF1 tumor suppressor in Schwann cells. PNFs are rich in immune cells, but whether immune cells are necessary for tumorigenesis is unknown. We show that inhibition of stimulator of interferon gene (STING) reduces plasma CXCL10, tumor T cell and dendritic cell (DC) recruitment, and tumor formation. Further, mice lacking XCR-1 + DCs showed reduced tumor-infiltrating T cells and PNF tumors. Antigen-presenting cells from tumor-bearing mice promoted CD8 + T cell proliferation in vitro, and PNF T cells expressed high levels of CCL5, implicating T cell activation. Notably, tumors and nerve-associated macrophages were absent in Rag1 -/- ; Nf1 f/f ; DhhCre mice and adoptive transfer of CD8 + T cells from tumor-bearing mice restored PNF initiation. In this setting, PNF shrunk upon subsequent T cell removal. Thus, STING pathway activation contributes to CD8 + T cell-dependent inflammatory responses required for PNF initiation and maintenance.

Background: Triple-negative breast cancer (TNBC) exhibits a lower survival rate in comparison to other BC subtypes. Utilizing dendritic cell (DC) vaccines as a form of immunotherapy is becoming a promising new approach to cancer treatment. However, inadequate immunogenicity of tumor antigens leads to unsatisfactory effectiveness of the DC vaccines. Exosomes are the basis for the latest improvements in tumor immunotherapy. This study examined whether TNBC-derived exosomes elicit immunogenicity on the maturation and function of monocyte-derived DCs and the impact of the exosome-treated monocyte-derived DCs (moDCs) on T cell differentiation., Methods: exosomes were isolated from MDA-MB-231 TNBC cancer cells and characterized. Monocytes were separated from peripheral blood mononuclear cells and differentiated into DCs. Then, monocyte-derived DCs were treated with TNBC-derived exosomes. Furthermore, the mRNA levels of the genes and cytokines involved in DC maturation and function were examined using qRT-PCR and ELISA assays. We also cocultured TNBC-derived exosome-treated moDCs with T cells and investigated the role of the treatment in T cell differentiation by evaluating the expression of some related genes by qRT-PCR. The concentration of the cytokines secreted from T cells cocultured with exosome-treated moDCs was quantified by the ELISA assays., Results: Our findings showed that TNBC-derived exosomes induce immunogenicity by enhancing moDCs' maturation and function. In addition, exosome-treated moDCs promote cocultured T-cell expansion by inducing TH1 differentiation through increasing cytokine production., Conclusion: TNBC-derived exosomes could improve vaccine-elicited immunotherapy by inducing an immunogenic response and enhancing the effectiveness of the DC vaccines. However, this needs to be investigated further in future studies., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

(1) Introduction: Toll-like receptors (TLRs) are key in immune response by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In gastric cancer (GC), TLR2, TLR3, TLR4, and TLR9 are crucial for modulating immune response and tumor progression. (2) Objective: This study aimed to assess the percentage of dendritic cells and monocytes expressing TLR2, TLR3, TLR4, and TLR9, along with the concentration of their soluble forms in the serum of GC patients compared to healthy volunteers. Factors such as disease stage, tumor type, age, and gender were also analyzed. (3) Materials and Methods: Blood samples from newly diagnosed GC patients and healthy controls were immunophenotyped using flow cytometry to assess TLR expression on dendritic cell subpopulations and monocytes. Serum-soluble TLRs were measured by ELISA. Statistical analysis considered clinical variables such as tumor type, stage, age, and gender. (4) Results: TLR expression was significantly higher in GC patients, except for TLR3 on classical monocytes. Soluble forms of all TLRs were elevated in GC patients, with significant differences based on disease stage but not tumor type, except for serum TLR2, TLR4, and TLR9. (5) Conclusions: Elevated TLR expression and soluble TLR levels in GC patients suggest a role in tumor pathogenesis and progression, offering potential biomarkers and therapeutic targets.

Purpose: Type I conventional dendritic cells (cDC1s) play a key role in priming anti-tumor cytotoxic T cells and inducing immune tolerance for self-antigens and tumor antigens. However, it remains unclear whether cDC1 has a protective or pathogenic role in multiple myeloma. We investigated a role of cDC1 in myeloma progression., Methods: A myeloma mouse model was performed by intravenous transplantation of Vk*MYC myeloma cells into XCR1-Diphtheria toxin receptor (DTR) knock-in or wild-type mice. Following injection with Diphtheria toxin (DT), monoclonal (M)-proteins and myeloma cells were analyzed by ELISA and flow cytometry., Results: Here we show that inducible depletion of cDC1 after myeloma transplantation markedly suppressed the progression of myeloma in the bone marrow and extramedullary sites, such as the spleen. cDC1 appeared in the bone marrow and spleen of myeloma-transplanted mice, which highly expressed CD103 and lowly produced interleukin (IL)-12. Consequently, the frequencies of exhausted CD8 T cells and regulatory T cells significantly decreased in the bone marrow of cDC1-depleted mice., Conclusions: cDC1 supports the progression of myeloma inducing exhausted CD8 T cells and regulatory T cells., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Suzuki, Komiya, Tsuda, Yoshino, Kaisho, Bergsagel, Kawamura, Fukuda and Tokoyoda.)

The regulation of intracellular ionic homeostasis to trigger antigen-specific immune responses has attracted extensive interest in tumor therapy. In this study, we developed a dual-pathway nanoreactor, Au-Cu 2-x Se@ZIF-8@P18 NPs (ACS-Z-P NPs), which targets danger-associated molecular patterns (DAMPs) and releases Zn 2+ and reactive oxygen species (ROS) within the tumor microenvironment (TME). Zn 2+ released from the metal-organic frameworks (MOFs) was deposited in the cytoplasm, leading to aberrant transcription levels of intracellular zinc-regulated proteins and DNA damage, thereby inducing pyroptosis and immunogenic cell death (ICD) dependent on caspase1/gasdermin D (GSDMD) pathway. Furthermore, upon laser irradiation, ACS-Z-P NPs could break through the limitations of inherent defects of immunosuppression in TME, enhance ROS generation through a Fenton-like reaction cascade, which subsequently triggered the activation of inflammatory vesicles and the release of damage-associated molecular patterns (DAMPs). This cascade effect led to the amplification of pyroptosis and immunogenic cell death (ICD), thereby remodeling the immunosuppressed TME. Consequently, this process improved dendritic cell (DC) antigen presentation and augmented anti-tumor T-cell responses, effectively initiating antigen-specific immune responses and further enhancing pyroptosis and ICD. This study explores the therapeutic properties of these mechanisms in detail. STATEMENT OF SIGNIFICANCE: The synthesized Au-Cu 2-x Se@ZIF-8@P18 nanoparticles (ACS-Z-Ps) can effectively enhance the body's immune response by regulating zinc ion levels within cells. This regulation leads to abnormal levels of zinc-regulated protein transcription and DNA damage, which induces cellular pyroptosis. As a result, antigen presentation to dendritic cells (DCs) is improved, and anti-tumor T-cell responses are enhanced. The ACS-Z-P NPs overcome the limitations of ROS deficiency and immunosuppression in the tumor microenvironment by using H 2 O 2 in the tumor microenvironment through a Fenton-like reaction. This leads to an increased production of ROS and O 2 , remodeling of the immunosuppressed tumor microenvironment, and enhanced induction of cell pyroptosis and immunogenic cell death. ACS-Z-P NPs targeted B16 cells using the photosensitizer P18 in combination with PDT treatment. This approach significantly inhibited the proliferation of B16 cells and effectively inhibited tumor growth., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

This study explores methods to isolate high-pure monocytes and optimize the best growth factor concentration to generate monocytes-derived dendritic cells (mo-DCs), subset DC1, which is crucial in immune responses. Three protocols for monocyte isolation from peripheral blood mononuclear cells (PBMCs) were evaluated: three-hour incubation on FBS-coated flasks; an overnight incubation on FBS-coated flasks; and Magnetic Activated Cell Sorting (MACS). Additionally, five different concentrations of human recombinant granulocyte-macrophage colony-stimulating factor (hrGM-CSF) and human recombinant interleukin-4 (hrIL-4) were compared. We used Flow cytometry to assess the isolation, purification, and generation of pure monocytes characterized as CD14 + , and expression of mo-DC classical markers (HLA-DR, CD80, CD83, and CD86). The obtained results show that monocytes isolated with the second method (overnight incubation) had the highest purity (P < 0.0001) but the lowest yield (P > 0.05), balancing purity and cost-effectiveness. A combination of hrGM-CSF and hrIL-4 at 400 U/mL produced the most favorable outcomes, leading to the highest rate of mo-DC generation (P < 0.05). Notably, this concentration resulted in increasing expression of HLA-DR, CD80, and CD86 surface markers in the generated DCs (P < 0.0001), with no changes in CD83 expression levels. In conclusion, this study offers valuable insights into selecting the optimal approach for monocyte isolation and mo-DC generation in various research contexts, providing a foundation for more effective immunological studies., (© 2024. The Author(s).)

Introduction: Adoptive cell therapy using TCR-engineered T-cells is one of the most effective strategies against tumor cells. The TCR T-cell approach has been well tested against a variety of blood neoplasms but is yet to be deeply tested against solid tumors. Among solid tumors, cancer-testis antigens are the most prominent targets for tumor-specific therapy, as they are usually found on cells that lie behind blood-tissue barriers., Methods: We have employed a novel efficient protocol for MAGE-A3-specific T-cell clonal expansion, performed single-cell multi-omic analysis of the expanded T-cells via BD Rhapsody, engineered a selected T-cell receptor into a lentiviral construct, and tested it in an in vitro LDH-cytotoxicity test., Results and Discussion: We have observed a 191-fold increase in the MAGE-A3-specific T-cell abundance, obtained a dominant T-cell receptor via single-cell multi-omic BD Rhapsody data analysis in the TCRscape bioinformatics tool, and observed potent cytotoxicity of the dominant-clonotype transduced TCR T-cells against a MAGE-A3-positive tumor. We have demonstrated the efficiency of our T-cell enrichment protocol in obtaining potent anti-tumor T-cells and their T-cell receptors, especially when paired with the modern single-cell analysis methods., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Sennikov, Volynets, Alrhmoun, Perik-Zavodskii, Perik-Zavodskaia, Fisher, Lopatnikova, Shevchenko, Nazarov, Philippova, Alsalloum, Kurilin and Silkov.)

Herein we report on the design, synthesis and biological evaluation of a series of nucleotide-binding oligomerization-domain-containing protein 2 (NOD2) desmuramylpeptide agonists. The structural prerequisites that shape both physicochemical and immunomodulatory profiles of desmuramylpeptide NOD2 agonists have been delineated. Within this context, we identified 3 , a butyrylated desmuramylpeptide, as a potent in vitro NOD2 agonist (EC 50 = 4.6 nM), exhibiting an almost 17-fold enhancement in potency compared to its unsubstituted counterpart 1 (EC 50 = 77.0 nM). The novel set of desmuramylpeptides demonstrate unique in vitro immunomodulatory activities. They elicited cytokine production in peripheral blood mononuclear cells (PBMCs), both alone and in conjunction with lipopolysaccharide (LPS). The spermine-decorated 32 also stimulated the LPS-induced cytotoxic activity (2.95-fold) of PBMCs against K562 cancer cells. Notably, the cholesterol-conjugate 26 displayed anti-inflammatory actions, highlighted by its capacity to convert the inflammatory monocyte subset into an anti-inflammatory phenotype. Finally, the eicosapentaenoylated derivative 23 augmented antigen presentation by mouse bone marrow-derived dendritic cells (BMDCs), thus highlighting its potential as a vaccine adjuvant.

Dendritic cells (DCs) within the tumor microenvironment (TME) have an insufficient capacity to activate T cells through antigen presentation. Furthermore, the programmed cell-death ligand 1 (PD-L1), abundantly expressed on tumor-associated DCs, binds the programmed cell-death 1 (PD-1)-positive T cells and suppresses their immune function. The binding of PD-L1 to CD80 (B7.1) on the same DC via cis -interactions further prevents T cell costimulation through CD28. Here, we present a strategy to simultaneously promote antigen cross-presentation and block the inhibitory interactions of PD-L1 on DCs to amplify T cell-mediated antitumor responses within the TME. Mesoporous silica nanoparticles (MSNPs) were loaded with clotrimazole (CLT) to boost MHC II-mediated antigen presentation by DCs, surface-modified with mannose to target CD206 on DCs, and then decorated with PD-L1 binding peptide (PDL1bp) to block PD-L1-mediated interactions. PDL1bp was cleaved from the mannosylated and CLT-loaded MSNPs (MSNP-MaN/CLT) under conditions simulating the TME and tethered to PD-L1 to reverse CD80 sequestration on DC2.4 cells. The blocking of PD-L1 by PDL1bp-decorated NPs (MSNP-MaN-PDL1bp) increased the cellular interactions between DC2.4 and EL4 T cells and the amount of IL-2 secretion. The MSNP-MaN/CLT were taken up rapidly by DC2.4 cells, promoted MHC II presentation of hen egg lysozyme (HEL), and increased IL-2 production from HEL antigen-primed 3A9 T cells, which was further enhanced by PDL1bp. In vivo investigation revealed that administration of the CLT-loaded and PDL1bp-functionalized MSNPs remarkably inhibited subcutaneous B16-F10 melanoma tumor growth when compared with anti-PD-L1 therapy. MSNP-MaN-PDL1bp/CLT treatment upregulated the levels of effector molecules such as granzyme B and proinflammatory cytokines (IFNγ and INFα) in the tumor tissue, indicating antitumoral T cell responses. This strategy of utilizing nanoparticles to trigger DC activation while promoting T cell stimulation can be used to amplify the antitumor T cell responses and represents a promising alternative to anti-PD-L1 immunotherapy.

Introduction: Live microfilariae (mf) and mf-derived extracellular vesicles (EVs) have been shown to modulate human antigen presenting cell (APC) function, most notably by suppressing the induction of IL-12 (and other pro-inflammatory cytokines) following activation with LPS and interferon-y., Methods: To explore further how EVs alter human APC function, we studied the effect of mf and EVs on human elutriated monocyte-derived dendritic cells (DC) following exposure to Mf, mf-derived excretory/secretory (E/S) products, E/S depleted of EVs through ultracentrifugation and purified EVs.  After demonstrating that the measurable responses induced by live mf could be recapitulated by EVs and EV-containing E/S, we next performed RNAseq analysis of human DC following exposure to live mf, EVs, E/S, or EV-depleted E/S., Results: In our analyses of the data for the DC, using a false discovery rate (FDR)<0.05, EV-exposed DC had induced the expression of 212 differentially expressed genes (DEGs) when compared to unexposed DC and 157 when compared to E/S-depleted EVs.  These genes were enriched in GO biological processes associated with neutrophil degranulation and 15 DEGs associated with KEGG Lysosome pathways. IPA analysis point to immune dysregulation. We next aimed to understand the intracellular processes altered by EVs and the effect these have on effector T cells. When SARS CoV-2 Membrane-specific CD4+ TCLs were assessed following EV conditioning of autologous DC and activation with the SARS CoV-2-Membrane peptide pool, we found conditioning reduced the frequency of SARS CoV-2 Membrane-specific CD3+ CD4+ CD154+ cells (p=.015). Similarly, EV-conditioning of SARS CoV-2 Membrane-specific CD3+ CD4+ cells induced fewer cell capable of producing IFN-γ (p=.045)., Discussion: Taken together, our data suggest a modulatory role of EVs on APC function that likely leads to defects in T cell effector function., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Sanku, Ricciardi, Redekar, Schaughency, Lack, Gazzinelli-Guimaraes and Nutman.)

Background: FANCA mutations have been detected in a variety of cancers and found to be pro-carcinogenic. However, no functional studies have been identified regarding the involvement of FANCA in the occurrence and the immune response of LUAD., Methods: The mRNA expression and overall survival rates of FANCA were evaluated by the TIMER, PrognoScan and TCGA database in LUAD tissues, and FANCA expression was further validated by clinical serum samples using ELISA. The correlation between FANCA and immune infiltration level was investigated via TISIDB database and CIBERSORT algorithm. The Kaplan-Meier plotter was used to further evaluate the prognostic value based on the expression levels of FANCA in related immune cells. Then, the influence of FANCA knockout on the proliferation, migration, and invasion of A549 and H1299 cells was validated using CCK8, cloning formation, and Transwell assays. Subsequently, HLA-A2-restricted FANCA antigenic peptides were predicted and synthesized by NetMHC4.0 and SYFPEITHI, and DCs were induced and cultured in vitro. Finally, DCs loaded with HLA-A2-restricted FANCA antigenic peptides were co-cultured with autologous peripheral blood lymphocyte to generate specific CTLs. The killing effects of different CTLs on LUAD cells were studied., Results: The results showed that high levels of FANCA in patients with LUAD were significantly correlated with worse OS survival, which was correlated with age, clinical stage, pathological T stage, M stage, and N stage in LUAD. Knockdown of FANCA in A549 and H1299 cells significantly inhibited proliferation, metastasis, and invasion in vitro. In addition, FANCA was significantly related to immune infiltrate, genomic alterations and TMB. FANCA expression infuenced the prognosis of LUAD patients by directly affecting immune cell infltration. Finally, HLA-A2-restricted FANCA antigenic peptides were synthesized. And FANCA 146-154 (SLLEFAQYL) antigenic peptide exhibit a stronger affinity for DCs, and induce CTLs to produce stronger targeted killing ability for LUAD cells at an effector-to-target ratio of 40:1., Conclusion: These results demonstrated that the elevation of FANCA promotes malignant phenotype of LUAD, and the potential peptide P2 (SLLEFAQYL) derived from FANCA may be used as an epitope vaccine for the treatment of LUAD., (© 2024. The Author(s).)

Dendritic cell (DC) activation and function are underpinned by profound changes in cellular metabolism. Several studies indicate that the ability of DCs to promote tolerance is dependent on catabolic metabolism. Yet the contribution of AMP-activated kinase (AMPK), a central energy sensor promoting catabolism, to DC tolerogenicity remains unknown. Here, we show that AMPK activation renders human monocyte-derived DCs tolerogenic as evidenced by an enhanced ability to drive differentiation of regulatory T cells, a process dependent on increased RALDH activity. This is accompanied by several metabolic changes, including increased breakdown of glycerophospholipids, enhanced mitochondrial fission-dependent fatty acid oxidation, and upregulated glucose catabolism. This metabolic rewiring is functionally important as we found interference with these metabolic processes to reduce to various degrees AMPK-induced RALDH activity as well as the tolerogenic capacity of moDCs. Altogether, our findings reveal a key role for AMPK signaling in shaping DC tolerogenicity and suggest AMPK as a target to direct DC-driven tolerogenic responses in therapeutic settings., (© 2024 Brombacher et al.)

Background: MARCKS (myristoylated alanine-rich C kinase substrates) serves as a substrate for protein kinase C, residing in the plasma membrane while acts as an actin filament crosslinking protein. This investigation aims to elucidate phosphorylated MARCKS (p-MARCKS) levels and activity in allergic asthma patients and explore the therapeutic potential of peptide inhibitors targeting p-MARCKS in an acute mouse model of allergic asthma., Methods: Immunohistochemistry and histology staining were employed on lung tissue slides to evaluate p-MARCKS expression and allergic asthma symptoms. Airway resistance was measured using invasive whole-body plethysmography. Flow cytometry detected lung dendritic cell migration, and migration/maturation assays were conducted on isolated murine bone marrow-derived dendritic cells (BM-DCs)., Results: Elevated p-MARCKS expression was observed in both human asthmatic tissues and animal models immunized with ovalbumin or Alternaria alternata. Remarkably, asthmatic individuals showed elevated high p-MARCKS expression in lung tissues. Intraperitoneal injection of the peptide MPS, targeting the MARCKS phosphorylation site domain, before allergen challenged, effectively suppressed MARCKS phosphorylation in murine lung tissues. MPS inhibited both in vivo and in vitro migration and maturation of dendritic cells (BM-DCs) and reduced Th2-related lymphocyte activation in bronchoalveolar lavage fluid (BALF). MPS pretreatment additionally suppressed all symptoms associated with allergic airway asthma, including a reduction in inflammatory cell influx, airway mucous cell metaplasia, and airway hyperreactivity., Conclusion: These findings suggest that phosphorylated MARCKS occurs in asthmatic lung tissue, and the inhibition of MARCKS phosphorylation by the MPS peptide reduces dendritic cell migration and Th2-related lymphocytes in the lungs in a murine model of acute asthma., Competing Interests: Declaration of competing interest The authors have no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Ethnopharmacological Relevance: WuHuTang (WHT) is a traditional Chinese medicine compound for treating asthma, and the evidence supports that it has a good effect on acute asthma attacks in children and adults. Respiratory syncytial virus (RSV) is an important factor in the pathogenesis of acute asthma attacks, and the effect on dendritic cells is the key to its pathogenesis. Previous studies have confirmed that the pathogenesis of viruses is related to exosomes. However, there are few studies on the exosomes induced by RSV. Whether WHT can improve the changes caused by RSV-induced exosomes or not is worthy of further exploration., Aim of the Study: We aim to study the effects of RSV-induced exosomes on the function and autophagy of dendritic cells, and to observe the intervention effect of WHT serum on the above effects., Methods: The co-culture model of exosomes derived from bone marrow mesenchymal stem cells induced by RSV (BMSCs-Exo-RSV) and dendritic cells was established, and then WHT serum was used to intervene. After 24 h of intervention, the CCK-8 method, flow cytometry, Elisa, RT-qCPR, and Western blot were used to detect the above-mentioned culture model., Results: RSV-induced exosomes had certain effects on viability, apoptosis, and costimulatory molecules generation of dendritic cells. At the same time, the levels of IL-6, IL-12, TNF-α, and autophagy increased, while the levels of IL-4, IL-10, and TGF-β decreased, and the AKT/TSC/mTOR pathway was inhibited. WHT serum could activate this pathway and reverse the above changes in dendritic cells., Conclusion: This study reveals that the pathogenic effect of RSV is related to the exosomes induced by RSV. The exosomes induced by RSV affect the function of dendritic cells by inhibiting the AKT/TSC/mTOR pathway, which can be activated by WHT to reverse the effects caused by RSV-induced exosomes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)