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Tianshu Li,1 Matthias Zehner,2 Jieyan He,3 Tomasz Próchnicki,4 Gabor Horvath,4 Eicke Latz,4 Sven Burgdorf,2 Shinji Takeoka1,31Institute for Advanced Research of Biosystem Dynamics, Waseda Research Institute for Science and Engineering, Waseda University, Tokyo, Japan; 2Molecular Immunology and Cell Biology, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany; 3Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan; 4Institute of Innate Immunity, Biomedical Center, University Hospitals, University of Bonn, Bonn, GermanyPurpose: The NLRP3 inflammasome activation has been proposed as a common mechanism for some adjuvants to boost the immune system, and cationic liposomes were reported to potentially activate the NLRP3 inflammasome. Herein, we questioned whether the NLRP3 inflammasome-activating cationic liposomes could promote antigen presentation and be applied as an immune adjuvant. In addition, we aimed to investigate the structure effect of lipid on triggering these immune responses.Materials and methods: A series of structurally similar lipids, consisting of arginine (Arg) head group and varied lengths of alkyl chains or spacers in between were used to prepare cationic liposomes. Lipopolysaccharide-primed human or murine macrophages or phorbol 12-myristate 13-acetate-primed THP-1 cells were treated with these liposomes, and interleukin (IL)-1β secretion was measured to quantify the NLRP3 inflammasome activation. Lysosome rupture was examined in THP-1 cells by the fluorescence loss of acridine orange, a lysosome dye. Further, chicken ovalbumin (OVA) was loaded on the liposome surface and applied to murine bone marrow-derived dendritic cells (BMDCs), which activate OT-I and OT-II lymphocytes upon major histocompatibility complex (MHC) class I- and class II-mediated antigen presentation, respectively. OT-I and OT-II cell division and IL-2 secretion were measured to evaluate the antigen presentation efficiency. The expressions of MHC molecules and co-stimulatory molecules ie, CD80, CD86, and CD40 on BMDCs were investigated by flow cytometry.Results: All the liposomes showed size distributions of 80–200 nm and zeta potentials of around 50 mV. A3C14 liposomes, consisting of Arg-C3-Glu2C14 lipids induced the most potent lysosome rupture and NLRP3 inflammasome activation. OVA-A3C14 also exhibited the most potent MHC class I- and class II-mediated antigen presentation in BMDCs without interfering MHC and co-stimulatory molecules.Conclusion: The hydrophobic moieties of arginine-based liposomes are crucial in stimulating innate immune cells. A3C14 liposomes were non-immunogenic but strongly activated innate immune cells and promoted antigen presentation, and therefore can be applied as immune adjuvants.Keywords: arginine, cationic liposomes, NLRP3 inflammasome activation, antigen presentation, lysosome rupture

Background: The aim of this study was to investigate the perioperative outcomes of robotic liver surgery (RLS) and Open liver surgery (OLS) in a centre with a high number of operations., Methods: A 1:1 propensity score matched (PSM) analysis of a retrospective database of RLS and OLS was performed. Cumulative sum (CUSUM) analysis was performed to identify learning curves., Result: After PSM analysis, operative time was significantly longer in the RLS group (p < 0.001). Estimated blood loss was significantly lower in the RLS group (p < 0.001). Transfusion rates were significantly lower in the RLS group. The length of hospital stay was shorter in the RLS group (3.5vs6.3 days, p < 0.001). Readmission rates were significantly lower in the RLS group (p < 0.049). CUSUM analysis showed a learning curve for at least 8 low-intermediate RLS procedures and 27 advanced-Expert RLS procedures., Conclusions: RLS has many advantages, including being safe to perform, less blood loss and faster postoperative recovery compared with OLS., (© 2024 The Author(s). The International Journal of Medical Robotics and Computer Assisted Surgery published by John Wiley & Sons Ltd.)

Background: Successful use of carbapenems in combination with cefazolin or oxacillin for treatment of MSSA bacteraemia has been described; however, comparative data to standard treatment approaches are lacking., Methods: This was a multicentre, retrospective study of adult patients with MSSA bacteraemia for >48 h. Standard treatment was considered monotherapy with cefazolin, oxacillin or nafcillin. Combination therapy was defined as the addition of ertapenem or meropenem to standard treatment for at least 24 h. The primary outcome was duration of bacteraemia defined as time from administration of an antibiotic with in vitro activity to first negative blood culture. Time to blood culture sterilization was compared through risk-set matching with aid of a propensity score., Results: Overall, 238 patients were included; 66% (157/238) received standard treatment and 34% (81/238) received combination therapy. The median (IQR) time to carbapenem initiation was 4.7 (3.63-6.5) days. Patients who received combination therapy were younger (P = 0.012), more likely to have endocarditis (P = 0.034) and had longer median duration of bacteraemia (P < 0.001). After applying risk-set matching, patients who received combination therapy experienced faster time to blood culture sterilization compared with control patients [HR = 1.618 (95% CI; 1.119-2.339) P = 0.011]. Using a paired hazard model, 90 day mortality rates were not statistically different among patients who received combination therapy versus matched controls [HR = 1.267 (95% CI; 0.610-2.678), P = 0.608]., Discussion: Carbapenem combination therapy resulted in faster time to blood culture sterilization, but no differences in overall mortality rates. Randomized trials are critical to determine the utility of carbapenem combination therapy., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Introduction: Distal Cholangiocarcinoma (dCCA) represents a challenge in hepatobiliary oncology, that requires nuanced post-resection prognostic modeling. Conventional staging criteria may oversimplify dCCA complexities, prompting the exploration of novel prognostic factors and methodologies, including machine learning algorithms. This study aims to develop a machine learning predictive model for recurrence after resected dCCA., Material and Methods: This retrospective multicentric observational study included patients with dCCA from 13 international centers who underwent curative pancreaticoduodenectomy (PD). A LASSO-regularized Cox regression model was used to feature selection, examine the path of the coefficient and create a model to predict recurrence. Internal and external validation and model performance were assessed using the C-index score. Additionally, a web application was developed to enhance the clinical use of the algorithm., Results: Among 654 patients, LNR (Lymph Node Ratio) 15, neural invasion, N stage, surgical radicality, and differentiation grade emerged as significant predictors of disease-free survival (DFS). The model showed the best discrimination capacity with a C-index value of 0.8 (CI 95 %, 0.77%-0.86 %) and highlighted LNR15 as the most influential factor. Internal and external validations showed the model's robustness and discriminative ability with an Area Under the Curve of 92.4 % (95 % CI, 88.2%-94.4 %) and 91.5 % (95 % CI, 88.4%-93.5 %), respectively. The predictive model is available at https://imim.shinyapps.io/LassoCholangioca/., Conclusions: This study pioneers the integration of machine learning into prognostic modeling for dCCA, yielding a robust predictive model for DFS following PD. The tool can provide information to both patients and healthcare providers, enhancing tailored treatments and follow-up., (© 2024 Elsevier Ltd, BASO ∼ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

This article is part of the Dendritic Cell Guidelines article series, which provides a collection of state-of-the-art protocols for the preparation, phenotype analysis by flow cytometry, generation, fluorescence microscopy, and functional characterization of mouse and human dendritic cells (DC) from lymphoid organs and various non-lymphoid tissues. Recent studies have provided evidence for an increasing number of phenotypically distinct conventional DC (cDC) subsets that on one hand exhibit a certain functional plasticity, but on the other hand are characterized by their tissue- and context-dependent functional specialization. Here, we describe a selection of assays for the functional characterization of mouse and human cDC. The first two protocols illustrate analysis of cDC endocytosis and metabolism, followed by guidelines for transcriptomic and proteomic characterization of cDC populations. Then, a larger group of assays describes the characterization of cDC migration in vitro, ex vivo, and in vivo. The final guidelines measure cDC inflammasome and antigen (cross)-presentation activity. While all protocols were written by experienced scientists who routinely use them in their work, this article was also peer-reviewed by leading experts and approved by all co-authors, making it an essential resource for basic and clinical DC immunologists., (© 2022 The Authors. European Journal of Immunology published by Wiley-VCH GmbH.)

Purpose: Tumors with involvement of common hepatic and gastroduodenal arteries (CHA and GDA) or GDA and the proper hepatic artery (PHA) are traditionally considered nonresectable. We have devised a new procedure that includes pancreaticoduodenectomy with preoperative hepatic artery embolization (PD-HAE) to facilitate an R0 resection of tumors involving the hepatic arteries without vascular anastomoses and complete sacrifice of normal hepatic arterial blood supply., Methods: To allow resection of the hepatic arteries, preoperative embolization of the PHA was performed to induce an increased collateral arterial blood flow from the periphery of the liver, far from the hepatic hilum 10-14 days prior to the operation. Between May 1, 2017 and December 31, 2019, eight patients with ductal adenocarcinoma were operated with the PD-HAE procedure., Results: The embolizations were uneventful apart from a transient marginal elevation of alanine aminotransferase in three patients. All patients had N disease with perineural invasion of tumor cells around the adventitia of the artery and severe perivascular inflammation. An R0 resection (> 1.0 mm to all resection margins) was obtained in six patients (75%). Mean hospital stay was 12 days. Median survival was 23 months (95% CI: 19.5-26.5 months). Six patients (75%) are still alive 11 to 36 months after the operation. There was perioperative fatality, and morbidity was comparable to standard pancreaticoduodenectomy., Conclusion: PD-HAE is a safe procedure and may provide the opportunity for curative resection in otherwise unresectable patients. However, larger studies are needed to evaluate this procedure., (© 2023. The Author(s).)

Brief Abstract: Today, the diagnosis and grading of mesenteric traction syndrome relies on a subjective assessment of facial flushing. However, this method has several limitations. In this study, Laser Speckle Contrast Imaging and a predefined cut-off value are assessed and validated for the objective identification of severe mesenteric traction syndrome., Background: Severe mesenteric traction syndrome (MTS) is associated with increased postoperative morbidity. The diagnosis is based on an assessment of the developed facial flushing. Today this is performed subjectively, as no objective method exists. One possible objective method is Laser Speckle Contrast Imaging (LSCI), which has been used to show significantly higher facial skin blood flow in patients developing severe MTS. Using these data, a cut-off value has been identified. This study aimed to validate our predefined LSCI cut-off value for identifying severe MTS., Methods: A prospective cohort study was performed on patients planned for open esophagectomy or pancreatic surgery from March 2021 to April 2022. All patients underwent continuous measurement of forehead skin blood flow using LSCI during the first hour of surgery. Using the predefined cut-off value, the severity of MTS was graded. In addition, blood samples for prostacyclin (PGI 2 ) analysis and hemodynamics were collected at predefined time points to validate the cut-off value., Main Results: Sixty patients were included in the study. Using our predefined LSCI cut-off value, 21 (35 %) patients were identified as developing severe MTS. These patients were found to have higher concentrations of 6-Keto-PGF aα (p = 0.002), lower SVR (p < 0.001), lower MAP (p = 0.004), and higher CO (p < 0.001) 15 min into surgery, as compared with patients not developing severe MTS., Conclusion: This study validated our LSCI cut-off value for the objective identification of severe MTS patients as this group developed increased concentrations of PGI 2 and more pronounced hemodynamic alterations compared with patients not developing severe MTS., Competing Interests: Conflict of interest All authors declare that they have no conflict of interest., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Centrosomes play a crucial role during immune cell interactions and initiation of the immune response. In proliferating cells, centrosome numbers are tightly controlled and generally limited to one in G1 and two prior to mitosis. Defects in regulating centrosome numbers have been associated with cell transformation and tumorigenesis. Here, we report the emergence of extra centrosomes in leukocytes during immune activation. Upon antigen encounter, dendritic cells pass through incomplete mitosis and arrest in the subsequent G1 phase leading to tetraploid cells with accumulated centrosomes. In addition, cell stimulation increases expression of polo-like kinase 2, resulting in diploid cells with two centrosomes in G1-arrested cells. During cell migration, centrosomes tightly cluster and act as functional microtubule-organizing centers allowing for increased persistent locomotion along gradients of chemotactic cues. Moreover, dendritic cells with extra centrosomes display enhanced secretion of inflammatory cytokines and optimized T cell responses. Together, these results demonstrate a previously unappreciated role of extra centrosomes for regular cell and tissue homeostasis., (© 2022 Weier et al.)

The mannose receptor is a member of the C-type lectin (CLEC) family, which can bind and internalize a variety of endogenous and pathogen-associated ligands. Because of these properties, its role in endocytosis as well as antigen processing and presentation has been studied intensively. Recently, it became clear that the mannose receptor can directly influence the activation of various immune cells. Cell-bound mannose receptor expressed by antigen-presenting cells was indeed shown to drive activated T cells towards a tolerogenic phenotype. On the other hand, serum concentrations of a soluble form of the mannose receptor have been reported to be increased in patients suffering from a variety of inflammatory diseases and to correlate with severity of disease. Interestingly, we recently demonstrated that the soluble mannose receptor directly promotes macrophage proinflammatory activation and trigger metaflammation. In this review, we highlight the role of the mannose receptor and other CLECs in regulating the activation of immune cells and in shaping inflammatory responses., 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 © 2021 van der Zande, Nitsche, Schlautmann, Guigas and Burgdorf.)

Background: An evaluation of the outcome after pancreatic surgery with focus on post-operative and late survival in elderly patients was performed., Methods: The study included 1.556 patients from a single HBP unit operated from 1. January 2010 to 31. December 2019. Patients were divided into two cohorts, < 75 years ( n  = 1.296) and ≥75 years ( n  = 260). Post-operative outcome was evaluated in all patients and late outcome in patients with adenocarcinoma in the pancreas ( n  = 765) and the duodenum ( n  = 117). The follow-up of patients with benign disease and adenocarcinoma was 57.95 (12.1-132.7) and 39.85 (12.0-131.7) months, respectively., Results: Length of hospital-stay and surgical complications were not significantly different in the two cohorts, but in-hospital death was 1.1% (<75 years) and 3.5% (≥75 years) ( p  = 0.008). The median overall survival of adenocarcinoma was 29.7 (<75 years) and 24.3 months (≥75 years) ( p  = 0.3228) with a one, two, and five-years survival of 74.5%, 56.6% and 28.6% vs. 73.6%, 51.1%, and 25.5%. Median time to relapse (46.2% of patients <75 years and 40.5% of patients ≥75 years) was 9 (1 - 51) and 8 (1 - 78) months (p = 0.534), respectively. Adjuvant chemotherapy did not have impact on the survival of the old cohort. Patients who died during the observation period had lost 94% (<75 years) and 87% (≥75 years) of expected remnant life. Estimated years lost in the old cohort was 4.2 in males and 4.9 in females ( p  = 0.025)., Conclusion: Elderly patients may undergo pancreatic surgery with a low mortality and for adenocarcinoma with an acceptable long-term survival., Competing Interests: Dr. Burgdorf has nothing to disclose. Dr. Storkholm has nothing to disclose. Dr. Chen has nothing to disclose. Dr. Palnæs has nothing to disclose., (© 2021 The Authors.)

Proinflammatory activation of macrophages in metabolic tissues is critically important in the induction of obesity-induced metaflammation. Here, we demonstrate that the soluble mannose receptor (sMR) plays a direct functional role in both macrophage activation and metaflammation. We show that sMR binds CD45 on macrophages and inhibits its phosphatase activity, leading to an Src/Akt/NF-κB-mediated cellular reprogramming toward an inflammatory phenotype both in vitro and in vivo. Remarkably, increased serum sMR levels were observed in obese mice and humans and directly correlated with body weight. Importantly, enhanced sMR levels increase serum proinflammatory cytokines, activate tissue macrophages, and promote insulin resistance. Altogether, our results reveal sMR as regulator of proinflammatory macrophage activation, which could constitute a therapeutic target for metaflammation and other hyperinflammatory diseases., Competing Interests: The authors declare no competing interest.

Macrophages (MΦ) and dendritic cells (DC), major players of the mononuclear phagocyte system (MoPh), are potent antigen presenting cells that steadily sense and respond to signals from the surrounding microenvironment, leading to either immunogenic or tolerogenic outcomes. Next to classical MHC-I/MHC-II antigen-presentation pathways described in the vast majority of cell types, a subset of MoPh (CD8 + , XCR1 + , CLEC9A + , BDCA3 + conventional DCs in human) is endowed with a high competence to cross-present external (engulfed) antigens on MHC-I molecules to CD8 + T-cells. This exceptional DC function is thought to be a crucial crossroad in cytotoxic antitumor immunity and has been extensively studied in the past decades. Biophysical and biochemical fingerprints of tumor micromilieus show significant spatiotemporal differences in comparison to non-neoplastic tissue. In tumors, low pH (mainly due to extracellular lactate accumulation via the Warburg effect and via glutaminolysis) and high oncotic and osmotic pressure (resulting from tumor debris, increased extracellular matrix components but in part also triggered by nutritive aspects) are-despite fluctuations and difficulties in measurement-likely the most constant general hallmarks of tumor microenvironment. Here, we focus on the influence of acidic and hypertonic micromilieu on the capacity of DCs to cross-present tumor-specific antigens. We discuss complex and in part controversial scientific data on the interference of these factors with to date reported mechanisms of antigen uptake, processing and cross-presentation, and we highlight their potential role in cancer immune escape and poor clinical response to DC vaccines.

Background: Patients with ductal adenocarcinoma in the body and/or tail of the pancreas with involvement of the common hepatic artery and/or celiac axis have until recently been considered unresectable. In selected cases, distal pancreatectomy (DP) with en bloc celiac axis resection (DP-CAR) may be an option to achieve R0 resection., Methods: Patients with tumours in the body and/or tail of the pancreas locally advanced with involvement of the common hepatic artery and/or celiac axis, with no distant metastases, were evaluated for DP-CAR procedures. Preoperative embolization was performed 10-14 days prior to surgery to enhance collateral arterial supply for the liver and stomach., Results: A total of 21 patients went through DP-CAR of whom 15 were preoperatively embolized. R0 resection vas achieved in 76% of the patients comparable to our standard distal pancreatectomies. The DP-CAR patients had a significant longer postoperative hospital stay, but no difference in major complications, including pancreatic fistulas compared with our standard distal pancreatectomies. No 30 nor 90 days postoperative mortality were recorded. Median survival in patients who underwent DP and DP-CAR procedures was 24.0 and 23.5 months, respectively (P > 0.5)., Conclusion: Outcomes after DP-CAR are comparable to standard distal pancreatectomies. DP-CAR after preoperative embolization is feasible and may in selected patients be a good option for treating patients with tumours in the body and/or tail of the pancreas with central arterial involvement.

Background: Patient interleukin (IL)-1β and IL-10 responses early in Staphylococcus aureus bacteremia (SaB) are associated with bacteremia duration and mortality. We hypothesized that these responses vary depending on antimicrobial therapy, with particular interest in whether the superiority of β-lactams links to key cytokine pathways., Methods: Three medical centers included 59 patients with SaB (47 methicillin-resistant S. aureus [MRSA], 12 methicillin-sensitive S. aureus [MSSA]) from 2015-2017. In the first 48 hours, patients were treated with either a β-lactam (n = 24), including oxacillin, cefazolin, or ceftaroline, or a glyco-/lipopeptide (n = 35), that is, vancomycin or daptomycin. Patient sera from days 1, 3, and 7 were assayed for IL-1β and IL-10 by enzyme-linked immunosorbent assay and compared using the Mann-Whitney U test., Results: On presentation, IL-10 was elevated in mortality (P = .008) and persistent bacteremia (P = .034), while no difference occurred in IL-1β. Regarding treatment groups, IL-1β and IL-10 were similar prior to receiving antibiotic. Patients treated with β-lactam had higher IL-1β on days 3 (median +5.6 pg/mL; P = .007) and 7 (+10.9 pg/mL; P = .016). Ex vivo, addition of the IL-1 receptor antagonist anakinra to whole blood reduced staphylococcal killing, supporting an IL-1β functional significance in SaB clearance. β-lactam-treated patients had sharper declines in IL-10 than vancomycin or daptomycin -treated patients over 7 days., Conclusions: These data underscore the importance of β-lactams for SaB, including consideration that the adjunctive role of β-lactams for MRSA in select patients helps elicit favorable host cytokine responses., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Antigen-presenting cells (APCs), especially macrophages and dendritic cells (DCs), are important for the induction of an adaptive immune response through their phagocytic capacity. APCs internalize extracellular antigens and, dependent on their intracellular localization, antigen-derived peptides are presented on MHC I or MHC II molecules. In context of antigen presentation and T cell activation tracking of internalized antigens is of high interest. In this article, we provide an immunofluorescence protocol and illustrate the analysis of intracellular routing of internalized antigens using the example of the model-antigen ovalbumin (OVA) in bone marrow-derived dendritic cells (BM-DCs). This protocol describes a procedure to stain such cells with an antibody against EEA-1, a marker for early endosomes, which can be easily adapted to other endosome markers, antigen-presenting cells, or antigens.

Dendritic cells have the ability to efficiently present internalized antigens on major histocompatibility complex (MHC) I molecules. This process is termed cross-presentation and is important role in the generation of an immune response against viruses and tumors, after vaccinations or in the induction of immune tolerance. The molecular mechanisms enabling cross-presentation have been topic of intense debate since many years. However, a clear view on these mechanisms remains difficult, partially due to important remaining questions, controversial results and discussions. Here, we give an overview of the current concepts of antigen cross-presentation and focus on a description of the major cross-presentation pathways, the role of retarded antigen degradation for efficient cross-presentation, the dislocation of antigens from endosomal compartment into the cytosol, the reverse transport of proteasome-derived peptides for loading on MHC I and the translocation of the cross-presentation machinery from the ER to endosomes. We try to highlight recent advances, discuss some of the controversial data and point out some of the major open questions in the field.

Human in vitro generated monocyte-derived dendritic cells (moDCs) and macrophages are used clinically, e.g., to induce immunity against cancer. However, their physiological counterparts, ontogeny, transcriptional regulation, and heterogeneity remains largely unknown, hampering their clinical use. High-dimensional techniques were used to elucidate transcriptional, phenotypic, and functional differences between human in vivo and in vitro generated mononuclear phagocytes to facilitate their full potential in the clinic. We demonstrate that monocytes differentiated by macrophage colony-stimulating factor (M-CSF) or granulocyte macrophage colony-stimulating factor (GM-CSF) resembled in vivo inflammatory macrophages, while moDCs resembled in vivo inflammatory DCs. Moreover, differentiated monocytes presented with profound transcriptomic, phenotypic, and functional differences. Monocytes integrated GM-CSF and IL-4 stimulation combinatorically and temporally, resulting in a mode- and time-dependent differentiation relying on NCOR2. Finally, moDCs are phenotypically heterogeneous and therefore necessitate the use of high-dimensional phenotyping to open new possibilities for better clinical tailoring of these cellular therapies., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Tissue osmolarity varies among different organs and can be considerably increased under pathologic conditions. Hyperosmolarity has been associated with altered stimulatory properties of immune cells, especially macrophages and dendritic cells. We have recently reported that dendritic cells upon exposure to hypertonic stimuli shift their profile towards a macrophage-M2-like phenotype, resulting in attenuated local alloreactivity during acute kidney graft rejection. Here, we examined how hyperosmotic microenvironment affects the cross-priming capacity of dendritic cells. Using ovalbumin as model antigen, we showed that exposure of dendritic cells to hyperosmolarity strongly inhibits activation of antigen-specific T cells despite enhancement of antigen uptake, processing and presentation. We identified TRIF as key mediator of this phenomenon. Moreover, we detected a hyperosmolarity-triggered, TRIF-dependent clustering of MHCI loaded with the ovalbumin-derived epitope, but not of overall MHCI molecules, providing a possible explanation for a reduced T cell activation. Our findings identify dendritic cells as important players in hyperosmolarity-mediated immune imbalance and provide evidence for a novel pathway of inhibition of antigen specific CD8 + T cell response in a hypertonic micromilieu.

N-glycosylation is generally accepted to enhance the immunogenicity of antigens because of two main reasons. First, the attachment of glycans enables recognition by endocytic receptors like the mannose receptor (MR) and hence increased uptake by dendritic cells (DCs). Second, foreign glycans are postulated to be immunostimulatory and their recognition could induce DC activation. However, a direct comparison between the immunogenicity of N-glycosylated vs. de-glycosylated proteins in vivo and a direct effect of N-glycosylated antigens on the intrinsic capacity of DCs to activate T cells have not been assessed so far.To analyze whether enforced N-glycosylation is a suited strategy to enhance the immunogenicity of non-glycosylated antigens for vaccination studies, we targeted non-glycoproteins towards the MR by introduction of artificial N-glycosylation using the methylotrophic yeast Komagataella phaffii (previously termed Pichia pastoris). We could demonstrate that the introduction of a single N-X-S/T motif was sufficient for efficient MR-binding and internalization. However, addition of N-glycosylated proteins neither influenced DC maturation nor their general capacity to activate T cells, pointing out that enforced N-glycosylation does not increase the immunogenicity of the antigen per se. Additionally, increased antigen-specific cytotoxic T cell responses in vivo after injection of N-glycosylated compared to de-glycosylated proteins were observed but this effect strongly depended on the epitope tested. A beneficial effect of N-glycosylation on antibody production could not be detected, which might be due to MR-cross-linking on DCs and to concomitant differences in IL-6 production by CD4+ T cells.These observations point out that the effect of N-glycosylation on antigen immunogenicity can vary between different antigens and therefore might have important implications for the development of vaccines using K. phaffii.

The mannose receptor (MR) is an endocytic receptor involved in serum homeostasis and antigen presentation. Here, we identify the MR as a direct regulator of CD8(+) T-cell activity. We demonstrate that MR expression on dendritic cells (DCs) impaired T-cell cytotoxicity in vitro and in vivo. This regulatory effect of the MR was mediated by a direct interaction with CD45 on the T cell, inhibiting its phosphatase activity, which resulted in up-regulation of cytotoxic T-lymphocyte-associated Protein 4 (CTLA-4) and the induction of T-cell tolerance. Inhibition of CD45 prevented expression of B-cell lymphoma 6 (Bcl-6), a transcriptional inhibitor that directly bound the CTLA-4 promoter and regulated its activity. These data demonstrate that endocytic receptors expressed on DCs contribute to the regulation of T-cell functionality., Competing Interests: The authors declare no conflict of interest.

Renal dendritic cells are a major component of the renal mononuclear phagocytic system. In the renal interstitium, these cells are exposed to an osmotic gradient, mainly sodium, whose concentration progressively increases towards inner medulla. Renal allograft rejection affects predominantly the cortex, suggesting a protective role of the renal medullary micromilieu. Whether osmolar variations can modulate the function of renal dendritic cells is currently undefined. Considering the central role of dendritic cells in promoting allorejection, we tested whether the biophysical micromilieu, particularly the interstitial osmotic gradient, influences their alloreactivity. There was a progressive depletion of leukocytes towards the medulla of homeostatic kidney. Only macrophages opposed this tendency. Flow cytometry of homeostatic and post-transplant medullary dendritic cells revealed a switch towards a macrophage-like phenotype. Similarly, bone marrow-derived dendritic cells developed ex vivo in sodium chloride-enriched medium acquired a M2-like signature. Microarray analysis of allotransplant dendritic cells posed a medullary downregulation of genes mainly involved in alloantigen recognition. Gene expression profiles of both medullary dendritic cells and bone marrow-derived dendritic cells matured in hyperosmolar medium had an overlap with the macrophage M2 signature. Thus, the medullary environment inhibits an alloimmune response by modulating the phenotype and function of dendritic cells., (Copyright © 2015 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)