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T cells respond swiftly, specifically, sensitively, and robustly to cognate antigens presented on the surface of antigen presenting cells. Existing microscopic models capture various aspects of early T-cell antigen receptor (TCR) signaling at the molecular level. However, none of these models account for the totality of the data, impeding our understanding of early T-cell activation. Here, we study early TCR signaling using Bayesian metamodeling, an approach for systematically integrating multiple partial models into a metamodel of a complex system. We inform the partial models using multiple published super-resolution microscopy datasets. Collectively, these datasets describe the spatiotemporal organization, activity, interactions, and dynamics of TCR, CD45 and Lck signaling molecules in the early-forming immune synapse, and the concurrent membrane alterations. The resulting metamodel accounts for a distinct nanoscale dynamic pattern that could not be accounted for by any of the partial models on their own: a ring of phosphorylated TCR molecules, enriched at the periphery of early T cell contacts and confined by a proximal ring of CD45 molecules. The metamodel suggests this pattern results from limited activity range for the Lck molecules, acting as signaling messengers between kinetically-segregated TCR and CD45 molecules. We assessed the potential effect of Lck activity range on TCR phosphorylation and robust T cell activation for various pMHC:TCR association strengths, in the specific setting of an initial contact. We also inspected the impact of localized Lck inhibition via Csk recruitment to pTCRs, and that of splicing isoforms of CD45 on kinetic segregation. Due to the inherent scalability and adaptability of integrating independent partial models via Bayesian metamodeling, this approach can elucidate additional aspects of cell signaling and decision making. [ABSTRACT FROM AUTHOR]

T-cell receptor gamma delta (TCRγδ) expressing T-cells are known to mediate an MHC-independent immune response and could therefore qualify for immune therapies. We examined the influence of dendritic cells(DC)/antigen presenting cell (APC) generated from blast-containing whole blood (WB) samples from AML and MDS patients on the provision of (leukemia-specific) TCRγδ expressing T-cells after mixed lymphocyte culture (MLC). Kit-M (granulocyte-macrophage colony-stimulating factor (GM-CSF) + prostaglandin E1 (PGE1)) or Kit-I (GM-CSF + Picibanil) were used to generate leukemia derived APC/DC (DC leu)from WB, which were subsequently used to stimulate T-cell enriched MLC. Immune cell composition and functionality were analysed using degranulation- (DEG), intracellular cytokine- (INTCYT) and cytotoxicity fluorolysis- (CTX) assays. Flow cytometry was used for cell quantification. We found increased frequencies of APCs/DCs and their subtypes after Kit-treatment of healthy and patients´ WB compared to control, as well as an increased stimulation and activation of several types of immune reactive cells after MLC. Higher frequencies of TCRγδ expressing leukemia-specific degranulation and intracellularly cytokine producing T-cells were found. The effect of Kit-M-treatment on frequencies of TCRγδ expressing cells and their degranulation could be correlated with the Kit-M-mediated blast lysis compared to control. We also found higher frequencies of TCRγδ expressing T-cells in AML patients´ samples with an achieved remission (compared to blast persistence) after induction chemotherapy. This might point to APC/DC-mediated effects resulting in the provision of leukemia-specific TCRγδ expressing T-cells: Moreover a quantification of TCRγδ expressing T-cells might contribute to predict prognosis of AML/MDS patients. • leukemia derived APC/leukemia derived dendritic cells induce TCRγδ expressing cells. • blastolytic potential ex vivo of TCRγδ expressing cells. • TCRγδ might be useful as a prognostic marker. [ABSTRACT FROM AUTHOR]

Allergy is a complex array of diseases influenced by innate and adaptive immunity, genetic polymorphisms, and environmental triggers. Atopic dermatitis is a chronic inflammatory skin disease characterized by barrier defects and immune dysregulation, sometimes leading to asthma and food allergies because of the atopic march. During atopic skin inflammation, Langerhans cells and dendritic cells (DCs) in the skin capture and deliver allergen information to local lymph nodes. DCs are essential immune sensors coordinating immune reactions by capturing and presenting antigens to T cells. In the context of allergic responses, DCs play a crucial role in instructing two types of helper T cells—type 2 helper T (Th2) cells and follicular helper T (TFH) cells—in allergic responses and IgE antibody responses. In skin sensitization, the differentiation and function of Th2 cells and TFH cells are influenced by skin-derived factors, including epithelial cytokines, chemokines, and signalling pathways to modify the function of migratory DCs and conventional DCs. In this review, we aim to understand the specific mechanisms involving DCs in allergic responses to provide insights into the pathogenesis of allergic diseases and potential therapeutic strategies. [ABSTRACT FROM AUTHOR]

The high prevalence of pain and the at times low efficacy of current treatments represent a significant challenge to healthcare systems worldwide. Effective treatment strategies require consideration of the diverse pathophysiologies that underlie various pain conditions. Indeed, our understanding of the mechanisms contributing to aberrant sensory neuron function has advanced considerably. However, sensory neurons operate in a complex dynamic microenvironment that is controlled by multidirectional interactions of neurons with non‐neuronal cells, including immune cells, neuronal accessory cells, fibroblasts, adipocytes, and keratinocytes. Each of these cells constitute and control the microenvironment in which neurons operate, inevitably influencing sensory function and the pathology of pain. This review highlights the importance of the neuronal microenvironment for sensory function and pain, focusing on cellular interactions in the skin, nerves, dorsal root ganglia, and spinal cord. We discuss the current understanding of the mechanisms by which neurons and non‐neuronal cells communicate to promote or resolve pain, and how this knowledge could be used for the development of mechanism‐based treatments. [ABSTRACT FROM AUTHOR]

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/Sdepleted 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-g (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. [ABSTRACT FROM AUTHOR]

Enhancing the efficacy of immunotherapy in brain metastases (BrM) requires an improved understanding of the immune composition of BrM and how this is affected by radiation and dexamethasone. Our two-arm pilot study (NCT04895592) allocated 26 patients with BrM to either low (Arm A) or high (Arm B) dose peri-operative dexamethasone followed by pre-operative stereotactic radiosurgery (pSRS) and resection (n= 13 per arm). The primary endpoint, a safety analysis at 4 months, was met. The secondary clinical endpoints of overall survival, distant brain failure, leptomeningeal disease and local recurrence at 12-months were 66%, 37.3%, 6%, and 0% respectively and were not significantly different between arms (p= 0.7739, p= 0.3884, p= 0.3469). Immunological data from two large retrospective BrM datasets and confirmed by correlates from both arms of this pSRS prospective trial revealed that BrM CD8 T cells were composed of predominantly PD1+ TCF1+ stem-like and PD1+ TCF1-TIM3+ effector-like cells. Clustering of TCF1+ CD8 T cells with antigen presenting cells in immune niches was prognostic for local control, even without pSRS. Following pSRS, CD8 T cell and immune niche density were transiently reduced compared to untreated BrM, followed by a rebound 6+ days post pSRS with an increased frequency of TCF1- effector-like cells. In sum, pSRS is safe and therapeutically beneficial, and these data provide a framework for how pSRS may be leveraged to maximize intracranial CD8 T cell responses. Radiation and steroid dosing can affect the immune composition of brain metastasis (BM). The authors have designed a pilot study of pre-operative stereotactic radiosurgery with low or high dose of peri-operative dexamethasone for resectable brain metastases, here reporting clinical outcomes and characterization of intratumor TCF1+ CD8+ stem-like T cell immune niches in the brain. [ABSTRACT FROM AUTHOR]

Several seminal plasma components, besides NGF, are implicated as ovulation-inducing factors in mammals. This study investigated the IL1B and its receptor IL1R1 in the testis (T), male accessory glands, prostate (P) and seminal vesicles (SV), and uterus (U) of adult rabbits using immunohistochemistry (IHC) and quantitative reverse transcription PCR (RT-qPCR). We also assessed the presence of IL1B in seminal plasma through Western blotting (WB) and examined the interaction between IL1B and NGF in vitro by measuring their production with enzyme-linked immunosorbent assay (ELISA) in the presence of NGF and IL1B alone or with their respective receptor antagonists. IHC revealed IL1B system expression in all reproductive organs studied, with IL1B and IL1R1 localized to the germinative epithelium of the T and the epithelial cells of the accessory glands and U. IL1B gene transcript levels were significantly higher (p < 0.01) in the P and SV compared to the T, while IL1R1 levels were significantly higher (p < 0.001) in the P compared to the other tissues, while IL1R1 levels were three times higher (p < 0.001) in the P. WB confirmed the presence of IL1B in seminal plasma with a 30–35 kDa band. The in vitro study demonstrated that IL1B increased (p < 0.05) basal NGF production in the U, whereas NGF had no effect on IL1B production. These findings provide evidence of the expression of the IL1B/IL1R1 system in both male and female rabbit reproductive tracts and suggest that IL1B in seminal plasma may influence uterine endocrine activity. The results propose a potential role for IL1B in ovulation, in conjunction with NGF, supporting that ovulation may involve inflammatory-like processes. [ABSTRACT FROM AUTHOR]

Chinese Herbal Medicine (CHM) is being more and more used in cancer treatment because of its ability to regulate the immune system. Chinese Herbal Medicine has several advantages over other treatment options, including being multi-component, multi-target, and having fewer side effects. Dendritic cells (DCs) are specialized antigen presenting cells that play a vital part in connecting the innate and adaptive immune systems. They are also important in immunotherapy. Recent evidence suggests that Chinese Herbal Medicine and its components can positively impact the immune response by targeting key functions of dendritic cells. In this review, we have summarized the influences of Chinese Herbal Medicine on the immunobiological feature of dendritic cells, emphasized an anti-tumor effect of CHM-treated DCs, and also pointed out deficiencies in the regulation of DC function by Chinese Herbal Medicine and outlined future research directions. [ABSTRACT FROM AUTHOR]

Antigen presenting cells sometimes require T cell "help" to kill and decompose microbes they capture, especially when those microbes resist effector molecules including nitric oxide and reactive oxygen species. Pathogens are more likely to resist those effectors, shared by the innate and adaptive immune systems, than are commensals. Does such resistance alert the immune system to the danger posed by those pathogens? Several lines of evidence suggest this occurs. Mouse studies showed a surprising exacerbation, not alleviation of experimental autoimmune encephalomyelitis, by suppression of nitric oxide production, but only when the suppression was applied to animals undergoing vaccination with myelin. In contrast, animals receiving T cells activated by vaccination without suppression of nitric oxide benefitted from reduced autoimmune cytotoxicity when nitric oxide production was suppressed after adoptive transfer. Vaccinia and adenovirus suppress nitric oxide production and have been successful vaccine platforms, also consistent with the above phagolysosomal resistance hypothesis. The hypothesis solves a long‐standing quandary—how can nitric oxide protect against both infection and autoimmunity, especially autoimmune diseases for which it seems a major effector? The importance of physical linkage between epitopes, first proposed in Bretscher's Two‐Step, Two‐Signal theory dependent on B cells, is extended to include phagolysosomal resistance in general, plus a corollary proposition that the immune system detects resistance to dissociation of high‐affinity pathogenic ligands from host binding sites to make neutralizing antibodies. [ABSTRACT FROM AUTHOR]

The high risk of patients with chronic lung diseases in developing into lung cancer has been recognised, but the key factors driving such procedure are still barely known. Dendritic cells (DCs) as major antigen presenting cells take part in the immune response in the very upstream, and myeloid DCs regulate the inflammation in pulmonary diseases. In this article, we performed single‐cell RNA sequencing (scRNA‐seq) analyses on DCs from pulmonary diseases. We explore the DC characteristics in chronic lung diseases, lung cancer and healthy control samples. We discover that a special type of DC, which is highly associated with inflammatory, inf‐DC, is abundant in lung cancer samples. Furthermore, we find that there are about 10% patients with chronic lung diseases also has such inf‐DC‐rich pattern. Such proportion is consistent to the fact that about 10% chronic lung disease patients finally developed into cancer. Our findings indicate inf‐DC could be a potential factor to predict the risk of chronic lung disease developing into cancer. [ABSTRACT FROM AUTHOR]

Controlled-release systems enhance anti-tumor effects by leveraging local antigen persistence for antigen-presenting cells (APCs) recruitment and T cell engagement. However, constant antigen presentation alone tends to induce dysfunction in tumor-specific CD8+ T cells, neglecting the synergistic effects of co-stimulatory signal. To address this, we developed a soft particle-stabilized emulsion (SPE) to deliver lipopeptides with controlled release profiles by adjusting their hydrophobic chain lengths: C 6 -SPE (fast release), C 10 -SPE (medium release), and C 16 -SPE (slow release). Following administration, C 6 -SPE release antigen rapidly, inducing early antigen presentation, whereas C 16 -SPE's slow-release delays antigen presentation. Both scenarios missed the critical window for coordinating with the expression of CD86, leading to either T cell apoptosis or suboptimal activation. In contrast, C 10 -SPE achieved a spatiotemporally synergetic effect of the MHC-I-peptide complex and co-stimulatory signal (CD86), leading to effective dendritic cell (DC) activation, enhanced T cell activation, and tumor regression in EG7-OVA bearing mice. Additionally, co-delivery of cytosine-phosphate-guanine (CpG) with SPE provided a sustained expression of the CD86 window for DC activation, improving the immune response and producing robust anti-tumor effects with C 6 -SPE comparable to C 10 -SPE. These findings highlight that synchronizing the spatiotemporal dynamics of antigen presentation and APC activation may confer an optimal strategy for enhanced vaccinations. [Display omitted] [ABSTRACT FROM AUTHOR]

mRNA-based vaccines symbolize a new paradigm shift in personalized medicine for the treatment of infectious and non-infectious diseases. However, the reactogenicity associated with the currently approved formulations limits their applicability in autoinflammatory disorders, such as tumour therapeutics. In this study, we present a delivery system showing controlled immunogenicity and minimal non-specific inflammation, allowing for selective delivery of mRNA to antigen presenting cells (APCs) within the medullary region of the lymph nodes. Our platform offers precise control over the trafficking of nanoparticles within the lymph nodes by optimizing stealth and targeting properties, as well as the subsequent opsonization process. By targeting specific cells, we observed a potent adaptive and humoral immune response, which holds promise for preventive and therapeutic anti-tumoral vaccines. Through spatial programming of nanoparticle distribution, we can promote robust immunization, thus improving and expanding the utilization of mRNA vaccines. This innovative approach signifies a remarkable step forward in the field of targeted nanomedicine. [Display omitted] [ABSTRACT FROM AUTHOR]

Adoptive cell therapy (ACT) is an immunotherapy strategy for cancer that has seen widespread clinical success. During ACT, patient-derived lymphocytes are stimulated with the antigen of interest ex vivo, proliferated, then returned to the patient to initiate an antigen-specific antitumor response. While effective, this process is resource-intensive and logistically impossible for many patients. Particulate artificial antigen presenting cells (aAPCs) offer a potential "off-the-shelf" alternative to ex vivo ACT. While particulate aAPCs perform well in vitro, they have had limited success in vivo due to poor bioavailability after injection. Barriers to bioavailability include rapid clearance, unfavorable biodistribution, and inadequate interactions with CD8+ T cells at sites of interest. Biomaterial properties such as elasticity have been shown to vastly impact the bioavailability and particle-cell interactions, but this has yet to be investigated in the context of aAPCs for in vivo T-cell stimulation. Previous literature likewise indicates that biomaterial properties, especially elasticity, can modulate T-cell activation in vitro. With the goal of creating a more biomimetic, next-generation particulate aAPC, we developed a poly(ethylene) glycol hydrogel particle platform with tunable elasticity to investigate the impact of elasticity on antigen-specific T cell activation for in vivo adoptive transfer. Using this knowledge, we were able to gain more precise control over in vivo T cell activation and investigate possible mechanisms including the effects of aAPC elasticity on T cell binding, macrophage uptake, and the protein corona. [ABSTRACT FROM AUTHOR]

Infection with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) impacts multiple anatomical sites. Whether this is due to the virus itself or is a secondary effect caused by the influx and activation of immune cells is not known. Positron emission tomography (PET) with immunoglobulins can provide insights into which sites and cells are activated in a living animal. Our aim is to use two nanobodies as tools to monitor (1) the distribution of antigen presenting cells (APC) by virtue of their Mafa‐DR expression profile, (2) virus‐infected cells and viral particles using a nanobody against the SARS‐CoV‐2 spike protein. Two [89Zr]‐labeled nanobodies that target the SARS‐CoV‐2 spike protein and major histocompatability complex (MHC) class II antigens (Mafa‐DR), respectively, are used to monitor their distribution during an experimental SARS‐CoV‐2 infection in a nonhuman primate model. Scans are obtained before infection and on Day 3 and 10 post infection (pi) in two macaques each. The [89Zr]anti‐SARS‐CoV‐2 spike nanobody localized to SARS‐CoV‐2‐associated lung lesions and the nasal mucosa, while the [89Zr]anti‐human leukocyte antigen (HLA)‐DR nanobody was predominantly found in non‐affected lung tissue after infection. We also detected, pi, upregulation of the Mafa‐DR signal, indicative of recruitment of professional APCs, in the superior sagittal sinus. [89Zr]‐labeled nanobodies show recruitment of macrophages/monocytes in non‐lesional lung tissue in cynomolgus macaques after experimental infection with SARS‐CoV‐2, as well as accumulation of the spike protein in both lung lesions and the nasal mucosa during infection. These results show the possibility of in vivo monitoring the quality and quantity of immune responses during the initial stages of an infection. [ABSTRACT FROM AUTHOR]

The tumor microenvironment (TME) and the cellular interactions within it can be critical to tumor progression and treatment response. Although technologies to generate multiplex images of the TME are advancing, the many ways in which TME imaging data can be mined to elucidate cellular interactions are only beginning to be realized. Here, we present a novel approach for multipronged computational immune synapse analysis (CISA) that reveals T-cell synaptic interactions from multiplex images. CISA enables automated discovery and quantification of immune synapse interactions based on the localization of proteins on cell membranes. We first demonstrate the ability of CISA to detect T-cell:APC (antigen presenting cell) synaptic interactions in two independent human melanoma imaging mass cytometry (IMC) tissue microarray datasets. We then verify CISA's applicability across data modalities with melanoma histocytometry whole slide images, revealing that T-cell:macrophage synapse formation correlates with T-cell proliferation. We next show the generality of CISA by extending it to breast cancer IMC images, finding that CISA quantifications of T-cell:B-cell synapses are predictive of improved patient survival. Our work demonstrates the biological and clinical significance of spatially resolving cell-cell synaptic interactions in the TME and provides a robust method to do so across imaging modalities and cancer types. Computational immune synapse analysis reveals T-cell synaptic interactions in tumor micro-environments using multiplex spatial protein images. [ABSTRACT FROM AUTHOR]

A robust T-cell expansion process involves co-culturing T-cells with nonproliferating feeder cells combined with anti-CD3 antibody and IL-2. Although ionizing irradiation effectively inhibits feeder cell proliferation, the high operating costs limit cell therapy research to well-funded institutions. UVC, known for causing DNA damage-induced cell death and commonly used for environmental sterilization, presents a cost-effective alternative to ionizing irradiation for generating non-proliferating feeder cells. UVC irradiation of K562 artificial antigen presenting cells (aAPCs) resulted in significant DNA damage, evidenced by increased g-H2AX phosphorylation within 15 minutes and elevated 8-OHdG levels at 24 hours. This indicates the occurrence of DNA double-strand breaks and oxidative damage. Following UVC irradiation, glucose uptake and ATP production were significantly reduced, whereas aCD3 retention at the surface of the cell increased twofold. Selective inhibition of glucose uptake and ATP production similarly enhanced aCD3 retention by approximately 10-fold and 6-fold, respectively. This suggests that UVC-induced energy deprivation dampens aCD3 internalization, potentially enhancing T-cell activation through prolonged aCD3 and T-cell receptor interaction. Tumor-infiltrating lymphocytes (TILs) expanded with UVC-irradiated PBMCs demonstrated comparable viability, expansion, immunophenotype, and effector function to those expanded with ionizing irradiation. UVC irradiation was equally effective in suppressing feeder cell proliferation and facilitating the expansion of functionally potent T-cells compared to traditional ionizing irradiation. Implementing UVC irradiation in Tcell expansion can significantly reduce costs, enhancing the accessibility and feasibility of cell therapy research across various institutions. [ABSTRACT FROM AUTHOR]

Abstract\nSUMMARYAluminum salt-based adjuvants like alum, alhydrogel and Adju-Phos are by far the most favored clinically approved vaccine adjuvants. They have demonstrated excellent safety profile and currently used in vaccines against diphtheria, tetanus, pertussis, hepatitis B, anthrax etc. These vaccinations cause minimal side effects like local inflammation at the injection site. Aluminum salt-based adjuvants primarily stimulate CD4+ T cells and B cell mediated Th2 immune response leading to generate a robust antibody response. In this review article, we have compiled the role of physio-chemical role of the two commonly used aluminum salt-based adjuvants alhydrogel and Adju-Phos, and the effect of surface properties, buffer composition, and adjuvant dosage on the immune response. After being studied for almost a century, researchers have come up with various mechanism by which these aluminum adjuvants activate the immune system. Firstly, we have covered the initial works of Glenny and his “repository effect” which paved the work for his successors to explore the involvement of cytokines, chemokines, recruitment of innate immune cells, enhanced antigen uptake by antigen presenting cells, and formation of NLRP3 inflammasome complex in mediating the immune response. It has been reported that aluminum adjuvants activate multiple immunological pathways which synergistically activates the immune system. We later discuss the recent developments in nanotechnology-based preparations of next generation aluminum based adjuvants which has enabled precise size control and morphology of the traditional aluminum adjuvants thereby manipulating the immune response as per our desire.Aluminum salt adjuvants like alum, aluminum hydroxide gel, and aluminum phosphate have been regularly used in vaccine formulations to potentiate the immune response. Despite being discovered nearly a century ago by Alexander Glenny, the cellular and molecular mechanism behind the working of these adjuvants is still elusive. In this article, we review the advances made in understanding the mechanism of action of these adjuvants. Firstly, we cover the “repository theory” put forward by Glenny, and gradually review the role of innate and adaptive immune cells, immune complexes, and different immunological pathways in aluminum adjuvant orchestrated immune response. We also take a dig into the role of physio-chemical parameters like surface properties, buffer composition and adjuvant dosage of aluminum adjuvants in eliciting an immune response. Finally, we discuss the advances made by nano-preparations of aluminum adjuvants and their diverse physio-chemical properties as well as hypothesize their probable mechanism of action. [ABSTRACT FROM AUTHOR]

Introduction: Adjuvants added to subunit vaccines augment antigen-specific immune responses. One mechanism of adjuvant action is activation of pattern recognition receptors (PRRs) on innate immune cells. Bordetella colonization factor A (BcfA); an outer membrane protein with adjuvant function, activates TH1/TH17-polarized immune responses to protein antigens from Bordetella pertussis and SARS CoV-2. Unlike other adjuvants, BcfA does not elicit a TH2 response. Methods: To understand the mechanism of BcfA-driven TH1/TH17 vs. TH2 activation, we screened PRRs to identify pathways activated by BcfA. We then tested the role of this receptor in the BcfA-mediated activation of bone marrow-derived dendritic cells (BMDCs) using mice with germline deletion of TLR4 to quantify upregulation of costimulatory molecule expression and cytokine production in vitro and in vivo. Activity was also tested on human PBMCs. Results: PRR screening showed that BcfA activates antigen presenting cells through murine TLR4. BcfA-treated WT BMDCs upregulated expression of the costimulatory molecules CD40, CD80, and CD86 and produced IL-6, IL-12/23 p40, and TNF-α while TLR4 KO BMDCs were not activated. Furthermore, human PBMCs stimulated with BcfA produced IL-6. BcfA-stimulated murine BMDCs also exhibited increased uptake of the antigen DQ-OVA, supporting a role for BcfA in improving antigen presentation to T cells. BcfA further activated APCs in murine lungs. Using an in vitro TH cell polarization system, we found that BcfA-stimulated BMDC supernatant supported TFH and TH1 while suppressing TH2 gene programming. Conclusions: Overall, these data provide mechanistic understanding of how this novel adjuvant activates immune responses. [ABSTRACT FROM AUTHOR]

Background: The heterogeneity of high-grade serous ovarian carcinoma (HGSOC) has hindered the clinical treatment, and our current study aims to characterize the change in tumor microenvironment (TME) with the progression of HGSOC via single cell RNA sequencing (scRNA-seq). Methods: The single-cell landscape in HGSOC was downloaded from the dataset GSE184880, which included 7 HGSOC and 5 normal samples and then applied for the filtering and annotation of cell clusters. The differentially expressed marker genes in these clusters were analyzed via "FindAllMarker" function in Seurat package and the functional enrichment analyses were implemented using clusterProflier package. Finally, the CellChat package was applied for the cell–cell communication analysis. Cellular experimental were determined Real-time Reverse Transcription Polymerase Chain Reaction (RT-qPCR). Results: 45,448 single cells were categorized into 10 cell clusters. The proportion of NK/T cells (49.5%), epithelial cells (15.3%) and myeloid cells (14%) was higher in the HGSOC samples. The heterogeneity and different enriched pathways of epithelial cells have been revealed with the progression of HGSOC from early to late stage, concurrent with the reduced activity of cytotoxic NK/T cells and the decreased capabilities of recruiting immune cells and presenting antigens in macrophages. Besides, the cell–cell communication analysis has revealed a strong communication of CXCL and CCL signal between M1 macrophages and cytotoxic NK/T cells in early stage of HGSOC. Moreover, RT-qPCR indicated that CCL4/5 and CCR1/5 levels were upregulated in tumor cell SK-OV-3. Conclusion: The investigation using scRNA-seq has depicted the change in cytotoxic NK/T cells, epithelial cells and myeloid cells of the TME of HGSOC, which may provide another insight into the specific mechanisms underlying the progression of HGSOC. [ABSTRACT FROM AUTHOR]

Following transplantation, human CD4+T cells can respond to alloantigen using three distinct pathways. Direct and semi-direct responses are considered potent, but brief, so contribute mostly to acute rejection. Indirect responses are persistent and prolonged, involve B cells as critical antigen presenting cells, and are an absolute requirement for development of donor specific antibody, so more often mediate chronic rejection. Novel in vitro techniques have furthered our understanding by mimicking in vivo germinal centre processes, including B cell antigen presentation to CD4+ T cells and effector cytokine responses following challenge with donor specific peptides. In this review we outline recent data detailing the contribution of CD4+ T follicular helper cells and antigen presenting B cells to donor specific antibody formation and antibody mediated rejection. Furthermore, multi-parametric flow cytometry analyses have revealed specific endogenous regulatory T and B subsets each capable of suppressing distinct aspects of the indirect response, including CD4+ T cell cytokine production, B cell maturation into plasmablasts and antibody production, and germinal centre maturation. These data underpin novel opportunities to control these aberrant processes either by targeting molecules critical to indirect alloresponses or potentiating suppression via exogenous regulatory cell therapy. [ABSTRACT FROM AUTHOR]

Summary: The early development of the neonatal immune system is profoundly influenced by exposure to dietary and microbial antigens, which shapes mucosal tolerance. Successful oral tolerance induction is crucially dependent on microbially imprinted immune cells, most notably the RORγt+ regulatory T (Treg) and antigen presenting cells and is essential for preventing food allergy (FA). The development of FA can be envisioned to result from disruptions at key checkpoints (CKPTs) that govern oral tolerance induction. These include gut epithelial sensory and effector circuits that when dysregulated promote pro‐allergic gut dysbiosis. They also include microbially imprinted immune regulatory circuits that are disrupted by dysbiosis and pro‐allergic immune responses unleashed by the dysregulation of the aforementioned cascades. Understanding these checkpoints is essential for developing therapeutic strategies to restore immune homeostasis in FA. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Due to the immunosuppressive tumor microenvironment (TME), T cells are usually inactivated and tend to differentiate into regulatory T cells (Tregs) in the tumor tissues, which seriously hinders the anti‐tumor efficiency of immunotherapy. In this study, an immune‐stimulating polypeptide hydrogel conjugated with an indoleamine‐2,3‐dioxygenase (IDO) inhibitor, 1‐methyl‐D‐tryptophan (D1MT), through a glutathione (GSH)‐responsive spacer was developed as an immunotherapy platform capable of regulating the TME. A combined immunotherapy system was further constructed through encapsulating doxorubicin (Dox) and immune checkpoint blocking antibody targeting programmed cell death protein 1 (aPD‐1) in the hydrogel. Dox released from the hydrogel could cause the immunogenic cell death (ICD) of tumor cells and induce the maturation of antigen presenting cells (APCs). After intratumoral injection, the multiple agent‐loaded hydrogel elicited effective anti‐tumor immunity in mice bearing B16F10 melanoma. Moreover, compared with the control hydrogel without D1MT, the immune‐stimulating hydrogel showed better efficiency in improving the immunosuppressive TME with increased number of activated T cells and reduced number of Tregs. Therefore, the immune‐stimulating hydrogel has great potential as a stimuli‐responsive platform for regulating suppressive TME and enhanced anti‐tumor chemo‐immunotherapy. [ABSTRACT FROM AUTHOR]

Abstract Background Current needle-based vaccination for respiratory viruses is ineffective at producing sufficient, long-lasting local immunity in the elderly. Direct pulmonary delivery to the resident local pulmonary immune cells can create long-term mucosal responses. However, criteria for drug vehicle design rules that can overcome age-specific changes in immune cell functions have yet to be established. Results Here, in vivo charge-based nanoparticle (NP) uptake was compared in mice of two age groups (2- and 16-months) within the four notable pulmonary antigen presenting cell (APC) populations: alveolar macrophages (AM), interstitial macrophages (IM), CD103+ dendritic cells (DCs), and CD11b+ DCs. Both macrophage populations exhibited preferential uptake of anionic nanoparticles but showed inverse rates of phagocytosis between the AM and IM populations across age. DC populations demonstrated preferential uptake of cationic nanoparticles, which remarkably did not significantly change in the aged group. Further characterization of cell phenotypes post-NP internalization demonstrated unique surface marker expression and activation levels for each APC population, showcasing heightened DC inflammatory response to NP delivery in the aged group. Conclusion The age of mice demonstrated significant preferences in the charge-based NP uptake in APCs that differed greatly between macrophages and DCs. Carefully balance of the targeting and activation of specific types of pulmonary APCs will be critical to produce efficient, age-based vaccines for the growing elderly population. Graphical Abstract

Foot and mouth disease (FMD) is a highly contagious infection caused by FMDvirus (FMDV) that affects livestock worldwide with significant economic impact. The main strategy for the control is vaccination with FMDV chemically inactivated with binary ethylenimine (FMDVi). In FMDV infection and vaccination, B cell response plays a major role by providing neutralizing/protective antibodies in animal models and natural hosts. Extracellular vesicles (EVs) and small EVs (sEVs) such as exosomes are important in cellular communication. EVs secreted by antigen-presenting cells (APC) like dendritic cells (DCs) participate in the activation of B and T cells through the presentation of native antigen membrane-associated to B cells or by transferring MHC-peptide complexes to T cells and even complete antigens from DCs. In this study, we demonstrate for the first time that APC activated with the FMDVi O1 Campos vaccine-antigens secrete EVs expressing viral proteins/peptides that could stimulate FMDV-specific immune response. The secretion of EVs-FMDVi is a time-dependent process and can only be isolated within the first 24 h post-activation. These vesicles express classical EVs markers (CD9, CD81, and CD63), along with immunoregulatory molecules (MHC-II and CD86). With an average size of 155 nm, they belong to the category of EVs. Studies conducted in vitro have demonstrated that EVs-FMDVi express antigens that can stimulate a specific B cell response against FMDV, including both marginal zone B cells (MZB) and follicular B cells (FoB). These vesicles can also indirectly or directly affect T cells, indicating that they express both B and T epitopes. Additionally, lymphocyte expansion induced by EVs-FMDVi is greater in splenocytes that have previously encountered viral antigens in vivo. The present study sheds light on the role of EVs derived fromAPC in regulating the adaptive immunity against FMDV. This novel insight contributes to our current understanding of the immune mechanisms triggered by APC during the antiviral immune response. Furthermore, these findings may have practical implications for the development of new vaccine platforms, providing a rational basis for the design of more effective vaccines against FMDV and other viral diseases. [ABSTRACT FROM AUTHOR]

Type 1 diabetes mellitus (T1DM) is characterized by absolute insulin deficiency primarily due to autoimmune destruction of pancreatic β‐cells. The prevailing treatment for T1DM involves daily subcutaneous insulin injections, but a substantial proportion of patients face challenges such as severe hypoglycemic episodes and poorly controlled hyperglycemia. For T1DM patients, a more effective therapeutic option involves the replacement of β‐cells through allogeneic transplantation of either the entire pancreas or isolated pancreatic islets. Unfortunately, the scarcity of transplantable human organs has led to a growing list of patients waiting for an islet transplant. One potential alternative is xenotransplantation of porcine pancreatic islets. However, due to inter‐species molecular incompatibilities, porcine tissues trigger a robust immune response in humans, leading to xenograft rejection. Several promising strategies aim to overcome this challenge and enhance the long‐term survival and functionality of xenogeneic islet grafts. These strategies include the use of islets derived from genetically modified pigs, immunoisolation of islets by encapsulation in biocompatible materials, and the creation of an immunomodulatory microenvironment by co‐transplanting islets with accessory cells or utilizing immunomodulatory biomaterials. This review concentrates on delineating the primary obstacles in islet xenotransplantation and elucidates the fundamental principles and recent breakthroughs aimed at addressing these challenges. [ABSTRACT FROM AUTHOR]

T cells express an enormous repertoire of T cell receptors, enabling them to recognize any potential antigen. This large repertoire undergoes stringent selections in the thymus, where receptors that react to self- or non-danger-associated-antigens are purged. We know that thymic tolerance depends on signals and antigens presented by the thymic antigen presenting cells, but we still do not understand precisely how many of these cells actually contribute to tolerance. This is especially true for thymic dendritic cells (DC), which are composed of diverse subpopulations that are derived from different progenitors. Although the importance of thymic DCs has long been known, the functions of specific DC subsets have been difficult to untangle. There remains insufficient systematic characterization of the ontogeny and phenotype of thymic APCs in general. As a result, validated experimental models for studying thymic DCs are limited. Recent technological advancement, such as multi-omics analyses, has enabled new insights into thymic DC biology. These recent findings indicate a need to re-evaluate the current tools used to study the function of these cells within the thymus. This review will discuss how thymic DC subpopulations can be defined, the models that have been used to assess functions in the thymus, and models developed for other settings that can be potentially used for studying thymic DCs. [ABSTRACT FROM AUTHOR]

Recently the FDA conducted a risk investigation and labeled the Boxed Warning for all BCMA- and CD19-directed CAR-T cell therapy, so does it mean that the public must take risk of secondary cancer to receive cell therapy? Here, without lentivirus and professional antigen presenting cell application, a novel tumor-specific T-cell therapy was successfully developed only by co-culturing MHC+ cancer cells and Naïve-T cells under the CD28 co-stimulatory signals. These tumor-specific T-cells could be separated through cell size and abundantly produced from peripheral blood, and would spontaneously attack target cells that carrying the same tumor antigen while avoiding others in vitro test. Moreover, it markedly decreased 90% tumor nodules companying with greatly improving overall survival (76 days vs 30 days) after twice infusion back to mice. This work maximally avoided the risks of secondary cancer and non-specific killing, and might open a revolutionary beginning of natural tumor-specific T-cell therapy. Highlights: Tumor specific T-cell generation without lentivirus and professional APC application. Only by co-culturing MHC+ cancer cell and Naïve-T cell supplying CD28 signal. Easy separation by cell size and fast generation from peripheral blood. Maximally avoid troubles of viral safety and non-specific reaction. Novel model of T-cell activation could be used to bioprospect medicinal molecules instead of CD28 from abundant natural products. [ABSTRACT FROM AUTHOR]

Background: Current needle-based vaccination for respiratory viruses is ineffective at producing sufficient, long-lasting local immunity in the elderly. Direct pulmonary delivery to the resident local pulmonary immune cells can create long-term mucosal responses. However, criteria for drug vehicle design rules that can overcome age-specific changes in immune cell functions have yet to be established. Results: Here, in vivo charge-based nanoparticle (NP) uptake was compared in mice of two age groups (2- and 16-months) within the four notable pulmonary antigen presenting cell (APC) populations: alveolar macrophages (AM), interstitial macrophages (IM), CD103+ dendritic cells (DCs), and CD11b+ DCs. Both macrophage populations exhibited preferential uptake of anionic nanoparticles but showed inverse rates of phagocytosis between the AM and IM populations across age. DC populations demonstrated preferential uptake of cationic nanoparticles, which remarkably did not significantly change in the aged group. Further characterization of cell phenotypes post-NP internalization demonstrated unique surface marker expression and activation levels for each APC population, showcasing heightened DC inflammatory response to NP delivery in the aged group. Conclusion: The age of mice demonstrated significant preferences in the charge-based NP uptake in APCs that differed greatly between macrophages and DCs. Carefully balance of the targeting and activation of specific types of pulmonary APCs will be critical to produce efficient, age-based vaccines for the growing elderly population. [ABSTRACT FROM AUTHOR]

Objective: Subsets of CD21−/low memory B cells (MBCs), including double‐negative (DN, CD27−IgD−) and Tbet+CD11c+ cells, are expanded in chronic inflammatory diseases. In rheumatoid arthritis (RA), CD21−/low MBCs correlate with joint destruction. However, whether this is due to the Tbet+CD11c+ subset, its function and pathogenic contribution to RA are unknown. This study aims to investigate the association between CD21−/lowTbet+CD11c+ MBCs and joint destruction as well as other clinical parameters and to elucidate their functional properties in patients with untreated RA (uRA). Methods: Clinical observations were combined with flow cytometry (n = 36) and single‐cell RNA sequencing (scRNA‐seq) and V(D)J sequencing (n = 4) of peripheral blood (PB) MBCs from patients with uRA. The transcriptome of circulating Tbet+CD11c+ MBCs was compared with scRNA‐seq data of synovial B cells. In vitro coculture of Tbet+CD11c+ B cells with T cells was used to assess costimulatory capacity. Results: CD21−/lowTbet+CD11c+ MBCs in PB correlated with bone destruction but no other clinical parameters analyzed. The Tbet+CD11c+ MBCs have undergone clonal expansion and express somatically mutated V genes. Gene expression analysis of these cells identified a unique signature of more than 150 up‐regulated genes associated with antigen presentation functions, including B cell receptor activation and clathrin‐mediated antigen internalization; regulation of actin filaments, endosomes, and lysosomes; antigen processing, loading, presentation, and costimulation; a transcriptome mirrored in their synovial tissue counterparts. In vitro, Tbet+CD11c+ B cells induced retinoic acid receptor–related orphan nuclear receptor γT expression in CD4+ T cells, thereby polarizing to Th17 cells, a T cell subset critical for osteoclastogenesis and associated with bone destruction. Conclusion: This study suggests that Tbet+CD11c+ MBCs contribute to the pathogenesis of RA by promoting bone destruction through antigen presentation, T cell activation, and Th17 polarization. [ABSTRACT FROM AUTHOR]

Cell death is a natural consequence of infection. However, although the induction of cell death was solely thought to benefit the pathogen, compelling data now show that the activation of cell death pathways serves as a nuanced antimicrobial strategy that couples pathogen elimination with the generation of inflammatory cytokines and the priming of innate and adaptive cellular immunity. Following cell death, the phagocytic uptake of the infected dead cell by antigen‐presenting cells and the subsequent lysosomal fusion of the apoptotic body containing the pathogen serve as an important antimicrobial mechanism that furthers the development of downstream adaptive immune responses. Despite the complexity of regulated cell death pathways, pathogens are highly adept at evading them. Here, we provide an overview of the remarkable diversity of cell death and efferocytic pathways and discuss illustrative examples of virulence strategies employed by pathogens, including oral pathogens, to counter their activation and persist within the host. [ABSTRACT FROM AUTHOR]

Antigen-presenting cells (APCs) are pivotal mediators of immune responses. Their role has increasingly been spotlighted in the realm of cancer immunology, particularly as our understanding of immunotherapy continues to evolve and improve. There is growing evidence that these cells play a non-trivial role in cancer immunity and have roles dependent on surface markers, growth factors, transcription factors, and their surrounding environment. The main dendritic cell (DC) subsets found in cancer are conventional DCs (cDC1 and cDC2), monocyte-derived DCs (moDC), plasmacytoid DCs (pDC), and mature and regulatory DCs (mregDC). The notable subsets of monocytes and macrophages include classical and non-classical monocytes, macrophages, which demonstrate a continuum from a pro-inflammatory (M1) phenotype to an anti-inflammatory (M2) phenotype, and tumor-associated macrophages (TAMs). Despite their classification in the same cell type, each subset may take on an immune-activating or immunosuppressive phenotype, shaped by factors in the tumor microenvironment (TME). In this review, we introduce the role of DCs, monocytes, and macrophages and recent studies investigating them in the cancer immunity context. Additionally, we review how certain characteristics such as abundance, surface markers, and indirect or direct signaling pathways of DCs and macrophages may influence tumor response to immune checkpoint blockade (ICB) therapy. We also highlight existing knowledge gaps regarding the precise contributions of different myeloid cell subsets in influencing the response to ICB therapy. These findings provide a summary of our current understanding of myeloid cells in mediating cancer immunity and ICB and offer insight into alternative or combination therapies that may enhance the success of ICB in cancers. [ABSTRACT FROM AUTHOR]

Bacterial synthesis of vitamin B2 generates a by‐product, 5‐(2‐oxopropylideneamino)‐d‐ribityl‐aminouracil (5‐OP‐RU), with potent immunological properties in mammals, but it is rapidly degraded in water. This natural product covalently bonds to the key immunological protein MR1 in the endoplasmic reticulum of antigen presenting cells (APCs), enabling MR1 refolding and trafficking to the cell surface, where it interacts with T cell receptors (TCRs) on mucosal associated invariant T lymphocytes (MAIT cells), activating their immunological and antimicrobial properties. Here, we strategically modify this natural product to understand the molecular basis of its recognition by MR1. This culminated in the discovery of new water‐stable compounds with extremely powerful and distinctive immunological functions. We report their capacity to bind MR1 inside APCs, triggering its expression on the cell surface (EC50 17 nM), and their potent activation (EC50 56 pM) or inhibition (IC50 80 nM) of interacting MAIT cells. We further derivatize compounds with diazirine‐alkyne, biotin, or fluorophore (Cy5 or AF647) labels for detecting, monitoring, and studying cellular MR1. Computer modeling casts new light on the molecular mechanism of activation, revealing that potent activators are first captured in a tyrosine‐ and serine‐lined cleft in MR1 via specific pi‐interactions and H‐bonds, before more tightly attaching via a covalent bond to Lys43 in MR1. This chemical study advances our molecular understanding of how bacterial metabolites are captured by MR1, influence cell surface expression of MR1, interact with T cells to induce immunity, and offers novel clues for developing new vaccine adjuvants, immunotherapeutics, and anticancer drugs. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to assess the anatomical possibilities of the jugular bulb (JB). Methods: Fifty archived CBCT scans were analyzed. Results: The average distance between the internal acoustic canal (IAC) and the JB was 7.97 mm on both sides (Right: SD = 2.56 mm, range 3.16–13.3 mm; Left: SD = 2.5 mm, range 2.9–13.6 mm). JB walls' pneumatization was classified into eight patterns. Deep petrosal cells (DPCs) prevailed in the lateral wall of the JB. The absence of pneumatization (NP) was commonly found on the left side. The presence of infralabyrinthine and hypotympanic cells varied. Less common types included accessory occipital cells (AOCs), posteromedial tracts (PMTs), and basi-occipital cells (BOCs), which determined a consistent variation of the lateral wall pneumatization patterns. Pneumatization of the medial wall was not observed in 50 right sides and 49 left sides. The inferior wall analysis revealed symmetry in AOC distribution and a predominant occurrence of NP. Cases with hypotympanum (HT) in the lateral wall showed a statistically significant IAC-JB distance increase by an average of 4.67 mm compared to NPs. Specific pneumatizations, particularly HT on the lateral side, have a significant effect on the IAC-JB distance, showing a clear pattern of increasing distance from DPC to NP and then to HT. A significant distance increase in HT pneumatization was noted. There were also recorded instances of JB hypoplasia and hyperplasia, JB diverticula, dehiscent JBs, and high JBs. Conclusion: This study establishes a novel classification of JB pneumatizations to aid in the understanding of the temporal bone anatomy. [ABSTRACT FROM AUTHOR]

Antigen presentation is a crucial mechanism that drives the T cell-mediated immune response and the development of Multiple Sclerosis (MS). Genetic alterations within the highly variable Major Histocompatibility Complex Class II (MHC II) have been proven to result in significant changes in the molecular basis of antigen presentation and the clinical course of patients with both Adult-Onset MS (AOMS) and Pediatric-Onset MS (POMS). Among the numerous polymorphisms of the Human Leucocyte Antigens (HLA), within MHC II complex, HLA-DRB1*15:01 has been labeled, in Caucasian ethnic groups, as a high-risk allele for MS due to the ability of its structure to increase affinity to Myelin Basic Protein (MBP) epitopes. This characteristic, among others, in the context of the trimolecular complex or immunological synapsis, provides the foundation for autoimmunity triggered by environmental or endogenous factors. As with all professional antigen presenting cells, macrophages are characterized by the expression of MHC II and are often implicated in the formation of MS lesions. Increased presence of M1 macrophages in MS patients has been associated both with progression and onset of the disease, each involving separate but similar mechanisms. In this critical narrative review, we focus on macrophages, discussing how HLA genetic alterations can promote dysregulation of this population's homeostasis in the periphery and the Central Nervous System (CNS). We also explore the potential interconnection in observed pathological macrophage mechanisms and the function of the diverse structure of HLA alleles in neurodegenerative CNS, seen in MS, by comparing available clinical with molecular data through the prism of HLA-immunogenetics. Finally, we discuss available and experimental pharmacological approaches for MS targeting the trimolecular complex that are based on cell phenotype modulation and HLA genotype involvement and try to reveal fertile ground for the potential development of novel drugs. [ABSTRACT FROM AUTHOR]

Persistent human papillomavirus (HPV) infection is associated with multiple malignancies. Developing therapeutic vaccines to eliminate HPV‐infected and malignant cells holds significant value. In this study, we introduced a lipid nanoparticle encapsulated mRNA vaccine expressing tHA‐mE7‐mE6. Mutations were introduced into E6 and E7 of HPV to eliminate their tumourigenicity. A truncated influenza haemagglutinin protein (tHA), which binds to the CD209 receptor on the surface of dendritic cells (DCs), was fused with mE7‐mE6 in order to allow efficient uptake of antigen by antigen presenting cells. The tHA‐mE7‐mE6 (mRNA) showed higher therapeutic efficacy than mE7‐mE6 (mRNA) in an E6 and E7+ tumour model. The treatment resulted in complete tumour regression and prevented tumour formation. Strong CD8+ T‐cell immune response was induced, contributing to preventing and curing of E6 and E7+ tumour. Antigen‐specific CD8+ T were found in spleens, peripheral blood and in tumours. In addition, the tumour infiltration of DC and NK cells were increased post therapy. In conclusion, this study described a therapeutic mRNA vaccine inducing strong anti‐tumour immunity in peripheral and in tumour microenvironment, holding promising potential to treat HPV‐induced cancer and to prevent cancer recurrence. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) are major contributors to immunological responses following solid organ transplantation. Donor derived EVs are best known for their role in transplant rejection through transferring donor major histocompatibility complex proteins to recipient antigen presenting cells, a phenomenon known as ‛cross‐decoration'. In contrast, donor liver‐derived EVs are associated with organ tolerance in small animal models. Therefore, the cellular source of EVs and their cargo could influence their downstream immunological effects. To investigate the immunological effects of EVs released by the liver in a physiological and transplant‐relevant model, we isolated EVs being produced during normothermic ex vivo liver perfusion (NEVLP), a novel method of liver storage prior to transplantation. We found EVs were produced by the liver during NEVLP, and these EVs contained multiple anti‐inflammatory miRNA species. In terms of function, liver‐derived EVs were able to cross‐decorate allogeneic cells and suppress the immune response in allogeneic mixed lymphocyte reactions in a concentration‐dependent fashion. In terms of cytokine response, the addition of 1 × 109 EVs to the mixed lymphocyte reactions significantly decreased the production of the inflammatory cytokines TNF‐α, IL‐10 and IFN‐γ. In conclusion, we determined physiologically produced liver‐derived EVs are immunologically regulatory, which has implications for their role and potential modification in solid organ transplantation. [ABSTRACT FROM AUTHOR]

IL-27, a member of the IL-6/IL-12 cytokine superfamily, is primarily secreted by antigen presenting cells, specifically by dendric cells, macrophages and B cells. IL-27 has antiviral activities and modulates both innate and adaptive immune responses against viruses. The role of IL-27 in the setting of viral infections is not well defined and both pro-inflammatory and anti-inflammatory functions have been described. Here, we discuss the latest advancements in the role of IL-27 in several viral infection models of human disease. We highlight important aspects of IL-27 expression regulation, the critical cell sources at different stages of the infection and their impact in cellmediated immunity. Lastly,we discuss the need to better define the antiviral andmodulatory (pro-inflammatory vs anti-inflammatory) properties of IL-27 in the context of human chronic viral infections. [ABSTRACT FROM AUTHOR]

Virus-like nanoparticles (VNP) are regarded as efficient vaccination platforms and have proven to be useful for the non-anaphylactogenic delivery of allergen-specific immunotherapy in preclinical models previously. Herein, we sought to determine the mode of VNP uptake by antigen presenting cells (APC). Accordingly, we screened a collection of substances known to inhibit different uptake pathways by APC. The human leukemia monocytic cell line THP-1 and the murine dendritic cell line DC 2.4 were examined for the uptake of fluorescently labelled VNP in the presence or absence of inhibitors. The inhibitory effect of candidate substances that blocked VNP uptake in APC lines was subsequently evaluated in studies with primary APC present in splenocyte and lung cell homogenates in vitro and upon intratracheal application of VNP in vivo. The uptake of allergen-specific VNP in vitro and in vivo was mainly observed by macrophages and CD103+ dendritic cells and was sensitive to inhibitors that block macropinocytosis, such as hyperosmolarity induced by sucrose or the polyphenol compound Rottlerin at low micromolar concentrations but not by other inhibitors. Also, T-cell proliferation induced by allergen-specific VNP was significantly reduced by both substances. In contrast, substances that stimulate macropinocytosis, such as Heparin and phorbol myristate acetate (PMA), increased VNP-uptake and may, thus, help modulate allergen-specific T-cell responses. We have identified macropinocytosis as the principal uptake mechanism of APC for allergen-specific VNP in vitro and in vivo, paving the way for further improvement of VNP-based therapies, especially those that can be used for tolerance induction in allergy, in the future. [ABSTRACT FROM AUTHOR]

Gammaherpesviruses (γHVs) are recognized as important pathogens in humans but their relationship with other animal hosts, especially wildlife species, is less well characterized. Our objectives were to examine natural Eptesicus fuscus gammaherpesvirus (EfHV) infections in their host, the big brown bat (Eptesicus fuscus), and determine whether infection is associated with disease. In tissue samples from 132 individual big brown bats, EfHV DNA was detected by polymerase chain reaction in 41 bats. Tissues from 59 of these cases, including 17 from bats with detectable EfHV genomes, were analyzed. An EfHV isolate was obtained from one of the cases, and electron micrographs and whole genome sequencing were used to confirm that this was a unique isolate of EfHV. Although several bats exhibited various lesions, we did not establish EfHV infection as a cause. Latent infection, defined as RNAScope probe binding to viral latency-associated nuclear antigen in the absence of viral envelope glycoprotein probe binding, was found within cells of the lymphoid tissues. These cells also had colocalization of the B-cell probe targeting CD20 mRNA. Probe binding for both latency-associated nuclear antigen and a viral glycoprotein was observed in individual cells dispersed throughout the alveolar capillaries of the lung, which had characteristics of pulmonary intravascular macrophages. Cells with a similar distribution in bat lungs expressed major histocompatibility class II, a marker for antigen presenting cells, and the existence of pulmonary intravascular macrophages in bats was confirmed with transmission electron microscopy. The importance of this cell type in γHVs infections warrants further investigation. [ABSTRACT FROM AUTHOR]

The aim of this review is to investigate the possible role of allergen immunotherapy (AIT) for house dust mites in the treatment of atopic dermatitis in adult patients (AD). AIT is a commonly accepted treatment for selected allergic diseases such as allergic rhinitis, bronchial asthma, allergy to venom, and sometimes food allergy. There have been a few original reports on improving AD symptoms due to subcutaneous and sublingual immunotherapy with selected allergens, mainly house dust mites. However, the precise role of immunotherapy in treating atopic dermatitis (AD) is still not clearly defined despite some studies that have been conducted. The review discusses available studies that provide evidence of the efficacy of AIT in patients with AD who are allergic to house dust mites. The authors focused on those studies in which the indication for AIT was mainly AD and only in patients with clinically confirmed allergy to house dust mites. Despite extensive evidence of the effectiveness of such treatment, studies on large patient populations are needed to determine the exact indications for AIT in AD patients with house dust mite allergy. [ABSTRACT FROM AUTHOR]

Simple Summary: Cancer stands as the second leading cause of death globally. Over the years, concerted efforts have been devoted to developing innovative and effective therapies for tumor eradication and to prevent recurrence. A critical factor contributing to therapy failures is the patient's immune response. Consequently, recent endeavors, such as immune checkpoint blockade, adoptive cell therapy, monoclonal antibodies, and cancer vaccines, aim to enhance a patient's immune system, maximizing the benefits of therapies for tumor clearance and subsequent memory formation. Dendritic cells (DCs) play a pivotal role in regulating the immune response. DCs are a heterogeneous population with varying functions in the tumor microenvironment. Reprogramming tumor-infiltrating DCs can dramatically improve the immune response against tumors and has shown significant therapeutic potential in pre-clinical models. In this review, we summarize the subsets and functions of dendritic cells and their role in shaping the anti-tumor T cell immune response. Among professional antigen-presenting cells, dendritic cells (DCs) orchestrate innate and adaptive immunity and play a pivotal role in anti-tumor immunity. DCs are a heterogeneous population with varying functions in the tumor microenvironment (TME). Tumor-associated DCs differentiate developmentally and functionally into three main subsets: conventional DCs (cDCs), plasmacytoid DCs (pDCs), and monocyte-derived DCs (MoDCs). There are two major subsets of cDCs in TME, cDC1 and cDC2. cDC1 is critical for cross-presenting tumor antigens to activate cytotoxic CD8+ T cells and is also required for priming earlier CD4+ T cells in certain solid tumors. cDC2 is vital for priming anti-tumor CD4+ T cells in multiple tumor models. pDC is a unique subset of DCs and produces type I IFN through TLR7 and TLR9. Studies have shown that pDCs are related to immunosuppression in the TME through the secretion of immunosuppressive cytokines and by promoting regulatory T cells. MoDCs differentiate separately from monocytes in response to inflammatory cues and infection. Also, MoDCs can cross-prime CD8+ T cells. In this review, we summarize the subsets and functions of DCs. We also discuss the role of different DC subsets in shaping T cell immunity in TME and targeting DCs for potential immunotherapeutic benefits against cancer. [ABSTRACT FROM AUTHOR]

Complications due to HCMV infection or reactivation remain a challenging clinical problem in immunocompromised patients, mainly due to insufficient or absent T‐cell functionality. Knowledge of viral targets is crucial to improve monitoring of high‐risk patients and optimise antiviral T‐cell therapy. To expand the epitope spectrum, genetically‐engineered dendritic cells (DCs) and fibroblasts were designed to secrete soluble (s)HLA‐A*11:01 and infected with an HCMV mutant lacking immune evasion molecules (US2‐6 + 11). More than 700 HLA‐A*11:01‐restricted epitopes, including more than 50 epitopes derived from a broad range of HCMV open‐reading‐frames (ORFs) were identified by mass spectrometry and screened for HLA‐A*11:01‐binding using established prediction tools. The immunogenicity of the 24 highest scoring new candidates was evaluated in vitro in healthy HLA‐A*11:01+/HCMV+ donors. Thus, four subdominant epitopes and one immunodominant epitope, derived from the anti‐apoptotic protein UL36 and ORFL101C (A11SAL), were identified. Their HLA‐A*11:01 complex stability was verified in vitro. In depth analyses revealed highly proliferative and cytotoxic memory T‐cell responses against A11SAL, with T‐cell responses comparable to the immunodominant HLA‐A*02:01‐restricted HCMVpp65NLV epitope. A11SAL‐specific T cells were also detectable in vivo in immunosuppressed transplant patients and shown to be effective in an in vitro HCMV‐infection model, suggesting their crucial role in inhibiting viral replication and improvement of patient's outcome. The developed in vitro pipeline is the first to utilise genetically‐engineered DCs to identify naturally presented immunodominant HCMV‐derived epitopes. It therefore offers advantages over in silico predictions, is transferable to other HLA alleles, and will significantly expand the repertoire of viral targets to improve therapeutic options. [ABSTRACT FROM AUTHOR]

Simple Summary: Despite the recent studies emphasizing the importance of the interferon gamma receptor (IFNγR) pathway in T cell-mediated cytotoxicity against solid tumors, full human ex vivo immune checkpoint drug screening remains a challenge. We employed an engineered gamma interferon activation site response element luciferase reporter (GAS-Luc2) for immune checkpoint drug screening in diverse ex vivo T cell–solid tumor cell co-culture systems. Three GAS-Luc2 reporter tumor cell lines endogenously expressing various immune checkpoints were engineered to produce quantifiable bioluminescence signal in the presence of an immune checkpoint inhibitor where activated T cells release IFNγ. These reporter cell lines also detected paracrine IFNγ signaling for immune checkpoint-targeted ADCC drug screening. Advancement into an artificial antigen-presenting cell line (aAPC) significantly enhanced T cell signaling for improved performance in these ex vivo immune checkpoint drug screening platforms. Recent studies highlight the integral role of the interferon gamma receptor (IFNγR) pathway in T cell–mediated cytotoxicity against solid but not liquid tumors. IFNγ not only directly facilitates tumor cell death by T cells but also indirectly promotes cytotoxicity via myeloid phagocytosis in the tumor microenvironment. Meanwhile, full human ex vivo immune checkpoint drug screening remains challenging. We hypothesized that an engineered gamma interferon activation site response element luciferase reporter (GAS-Luc2) can be utilized for immune checkpoint drug screening in diverse ex vivo T cell–solid tumor cell co-culture systems. We comprehensively profiled cell surface proteins in ATCC's extensive collection of human tumor and immune cell lines, identifying those with endogenously high expression of established and novel immune checkpoint molecules and binding ligands. We then engineered three GAS-Luc2 reporter tumor cell lines expressing immune checkpoints PD-L1, CD155, or B7-H3/CD276. Luciferase expression was suppressed upon relevant immune checkpoint–ligand engagement. In the presence of an immune checkpoint inhibitor, T cells released IFNγ, activating the JAK-STAT pathway in GAS-Luc2 cells, and generating a quantifiable bioluminescent signal for inhibitor evaluation. These reporter lines also detected paracrine IFNγ signaling for immune checkpoint-targeted ADCC drug screening. Further development into an artificial antigen-presenting cell line (aAPC) significantly enhanced T cell signaling for superior performance in these ex vivo immune checkpoint drug screening platforms. [ABSTRACT FROM AUTHOR]

Treatments directly targeting fibrosis remain limited. Given the unique intrinsic features of macrophages and their capacity to engraft in the liver, we genetically engineered bone marrow-derived macrophages with a chimeric antigen receptor (CAR) to direct their phagocytic activity against hepatic stellate cells (HSCs) in multiple mouse models. This study aimed to demonstrate the therapeutic efficacy of CAR macrophages (CAR-Ms) in mouse models of fibrosis and cirrhosis and to elucidate the underlying mechanisms. uPAR expression was studied in patients with fibrosis/cirrhosis and in murine models of liver fibrosis, including mice treated with carbon tetrachloride, a 5-diethoxycarbonyl-1, 4-dihydrocollidine diet, or a high-fat/cholesterol/fructose diet. The safety and efficacy of CAR-Ms were evaluated in vitro and in vivo. Adoptive transfer of CAR-Ms resulted in a significant reduction in liver fibrosis and the restoration of function in murine models of liver fibrosis. CAR-Ms modulated the hepatic immune microenvironment to recruit and modify the activation of endogenous immune cells to drive fibrosis regression. These CAR-Ms were able to recruit and present antigens to T cells and mount specific antifibrotic T-cell responses to reduce fibroblasts and liver fibrosis in mice. Collectively, our findings demonstrate the potential of using macrophages as a platform for CAR technology to provide an effective treatment option for liver fibrosis. CAR-Ms might be developed for treatment of patients with liver fibrosis. Liver fibrosis is an incurable condition that afflicts millions of people globally. Despite the clear clinical need, therapies for liver fibrosis are limited. Our findings provide the first preclinical evidence that chimeric antigen receptor (CAR)-macrophages (CAR-Ms) targeting uPAR can attenuate liver fibrosis and cirrhosis. We show that macrophages expressing this uPAR CAR exert a direct antifibrotic effect and elicit a specific T-cell response that augments the immune response against liver fibrosis. These findings demonstrate the potential of using CAR-Ms as an effective cell-based therapy for the treatment of liver fibrosis. [Display omitted] • Macrophages genetically engineered with a CAR targeting uPAR phagocytosed HSCs. • CAR-Ms are effective against liver fibrosis of different etiologies. • CAR-Ms modulate the local tissue microenvironment to drive fibrosis regression. • CAR-Ms elicit a specific T-cell response that augments the immune response against liver fibrosis. [ABSTRACT FROM AUTHOR]

Invasive Aspergillosis (IA) is a severe and fatal infection, especially in immunocompromised patients. Galactomannan is a polysaccharide antigen present in the cell wall of Aspergillus species, which is secreted into the blood and other body fluids during hyphal growth. Therefore, detecting galactomannan antigen is very useful in diagnosing IA, along with clinical features and radiological findings. The study period was one year (January 2022 to December 2022). The data was collected retrospectively from the medical records and case sheets of all clinically suspected invasive aspergillosis patients. Galactomannan antigen assay was performed using an FDA-approved Platelia Aspergillus EIA test kit, and results were interpreted according to the manufacturer’s instructions (Cut off > 0.5). A total of 236 clinically suspected Invasive Aspergillosis cases were enrolled in the study. Galactomannan positivity was predominantly seen in patients aged 40 – 60 years, with male preponderance. Of 236 patients, 14.40% were immunocompromised, and 85.59% were immunocompetent. According to EORTC/MSG definitions, we got one proven IA case, 21 probable cases (8.89%), and nine (3.81%) possible cases. In immunocompetent individuals also, we observed 48.72% (115/236) galactomannan positivity, especially in old Pulmonary Tuberculosis (PTB) patients. Galactomannan positivity was higher in Broncho alveolar lavage (BAL) samples (n=70, 85.36%) than in serum samples (n=77, 46.67%). We found culture positivity of 14.06%, with Aspergillus fumigatus being the commonest isolate, followed by Aspergillus flavus. There is increased positivity of galactomannan in BAL samples compared to serum; hence BAL is a better specimen for diagnosis of Invasive Pulmonary Aspergillosis (IPA). [ABSTRACT FROM AUTHOR]

Ferroptosis is an iron‐dependent cell death form that initiates lipid peroxidation (LPO) in tumors. In recent years, there has been growing interest on ferroptosis, but how to propel it forward translational medicine remains in mist. Although experimental ferroptosis inducers such as RSL3 and erastin have demonstrated bioactivity in vitro, the poor antitumor outcome in animal model limits their development. In this study, we reveal a novel ferroptosis inducer, oxaliplatin–artesunate (OART), which exhibits substantial bioactivity in vitro and vivo, and we verify its feasibility in cancer immunotherapy. For mechanism, OART induces cytoplasmic and mitochondrial LPO to promote tumor ferroptosis, via inhibiting glutathione‐mediated ferroptosis defense system, enhancing iron‐dependent Fenton reaction, and initiating mitochondrial LPO. The destroyed mitochondrial membrane potential, disturbed mitochondrial fusion and fission, as well as downregulation of dihydroorotate dehydrogenase mutually contribute to mitochondrial LPO. Consequently, OART enhances tumor immunogenicity by releasing damage associated molecular patterns and promoting antigen presenting cells maturation, thereby transforming tumor environment from immunosuppressive to immunosensitive. By establishing in vivo model of tumorigenesis and lung metastasis, we verified that OART improves the systematic immune response. In summary, OART has enormous clinical potential for ferroptosis‐based cancer therapy in translational medicine. [ABSTRACT FROM AUTHOR]