Antigen-presenting Function Research Articles

P-61 EYE SEE YOU: GRAVES' OPHTHALMOPATHY: FIRST OCCURRENCE 10 YEARS POST-THYROIDECTOMY

Abstract Introduction Graves' ophthalmopathy is most commonly associated with Graves' disease and less frequently with Hashimoto's thyroiditis. Graves’ ophthalmopathy is also known as thyroid-associated ophthalmopathy or thyroid eye disease, because it sometimes occurs in patients with euthyroid or hypothyroid chronic autoimmune thyroiditis. While de novo Graves’ ophthalmopathy has been seen after definitive treatment with radioactive iodine, it is uncommon after total thyroidectomy. Clinical Case We report the case of a 74-year-old female, non-smoker, with a history of nodular goiter who underwent total thyroidectomy. Ten years post-surgery, the patient reported unilateral exophthalmos in the left eye accompanied by retro-orbital pain. Neck ultrasound showed no residual thyroid tissue, additionally, the levels for thyroid-stimulating hormone receptor antibodies (TRAb), thyroid peroxidase antibodies (TPOAb), and antithyroglobulin antibodies (TGAb) were negative. Consequently, ophthalmologic and neurological evaluation as well as orbital magnetic resonance imaging (MRI) were recommended. Initially, the histopathological result of nodular goiter and the negative TRAB levels ruled out Graves' disease. However, the orbital MRI did not reveal any other causes or local lesions, raising the suspicion of Graves' ophthalmopathy despite negative TRAB levels. Given the patient's active ophthalmopathy (clinical activity score 4), treatment with methylprednisolone was initiated, with symptomatic improvement by the end of therapy. Two years later, an elevated TRAB level was detected for the first time, and neck ultrasound revealed residual tissue in the left thyroid bed. We attributed this to the antibodies stimulation on a possible minimal residual thyroid tissue, which was undetectable on periodic ultrasound for a over 10 years, but which subsequently became hyperplastic. Therefore, corroborating the anamnestic, clinical and paraclinical data, the diagnosis of Graves' ophtalmopathy with positive TRAB has been confirmed. The most recent follow-up revealed an improved but still active nature of the ophthalmopathy (clinical activity score 3), hence, treatment with methylprednisolone and mycophenolate sodium was reinitiated. The patient is being closely monitored to establish the best ongoing therapeutic approach. Conclusion The development of Graves' ophthalmopathy after total thyroidectomy for nodular goiter is a rare occurrence with several proposed mechanisms. These include the release of thyroid autoantigens post-surgery triggering an autoimmune response, potential alterations in antigen-presenting cell function influencing immune reactions, and the impact of postoperative infections on immune modulation. While the exact pathways remain speculative, understanding these mechanisms could enhance our approach to monitoring and managing autoimmune complications in thyroid surgery patients.Figure 1:Orbital MRIThe orbital MRI shows that the posterior pole of the right eyeball is approximately 3 mm anterior to the interzygomatic line and the posterior pole of the left eyeball is at the level of the interzygomatic line. The distance between the interzygomatic line and the anterior pole of the eyeball is approximately 25 mm on the right side and 23 mm on the left side. Bilateral extraocular muscles with increased thickness, homogeneous enhancement, more intense on the right side.

Characterizing the diabetes-induced pathological changes of the mouse lung by single-cell RNA sequencing.

Pulmonary disorders are exacerbated by high blood sugar, leading to a disordered immune defense and increased susceptibility to infection. Type 2 diabetes mellitus (T2D) is characterized by insulin resistance and inadequate insulin production. Mechanisms leading to pulmonary alternation due to T2D are not clear. The advancements in single-cell RNA sequencing aid in characterizing the effects of T2D on lungs and its altered mechanisms. Our results first revealed that in late-stage diabetic mice, the number of immune cells in the lungs significantly increased, with these immune cells predominantly being immature polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). At the early stages of diabetes, alveolar cell type I and type II (AT I & II) exhibited a mesenchymal phenotype and showed reduced expression of several key cytokines essential for maintaining lung immunity, including Cxcl15, Cxcl14, and Il34. Additionally, the antigen-presenting cell function of AT II, resulting from the downregulation of several MHC type II proteins, was markedly diminished in diabetic mice. Moreover, decreased expressions of interferon-related genes Ifnar1 and Ifnar2, along with impaired Sftpd expression, compromised lung immunity impairment in diabetic mice. These pathogenic changes contributed to the increased susceptibility and severity of respiratory syncytial virus and tuberculosis in the lung of diabetes. In addition to alveolar cells, pulmonary capillary endothelial cells also exhibited an immature transition phenotype, with a significant increase in angiogenic capacity. Our findings provided a comprehensive exploration of lung pathology under the influence of diabetes and explained the multiple factors impacting lung immunity in diabetic conditions.

The double-edged sword role of natural Killer cells in Parkinson's disease.

Neurological disorders are the leading cause of disability worldwide, with Parkinson's disease (PD) emerging as a rapidly growing neurological condition on a global scale. Although treatments exist to alleviate symptoms and maintain patients' quality of life, PD remains incurable. According to some recent studies, natural killer (NK) cells may play a role in clearing alpha-synuclein aggregates, which are the main component of Lewy bodies that cause neuronal degeneration in Parkinson's disease. NK cells may also have an adverse impact on this condition by modulating inflammation and antigen-presenting cell function. Modifying NK cells derived from diverse sources, such as umbilical cord blood, presents a promising avenue for immunotherapy in PD patients, particularly during the early stages of the condition. Consequently, further research is essential to elucidate the mechanisms by which NK cells operate in Parkinson's patients and to assess their viability as potential biomarkers or therapeutic targets.

SQYC formula improves the efficacy of PD-1 monoclonal antibodies in MSS colorectal cancer by regulating dendritic cell mitophagy via the PINK1-Parkin pathway.

Microsatellite stable (MSS) colorectal carcinomas (CRCs) exhibit poor responsiveness to immunotherapy such as immune checkpoint inhibitors (ICIs). In the realm of clinical cancer treatment, traditional Chinese medicines (TCMs) are extensively utilized for their immunomodulatory properties. Shen Qi Yi Chang (SQYC), a clinical prescription for CRC treatment, improve the life quality of CRC patients and enhance their immune function. This study was to reveal the effect and mechanism of SQYC in improving the effect of PD-1 inhibitors in the treatment of MSS-type CRC. CT26-luc in situ CRC tumor model and human CRC organoid model was established to evaluate the anti-tumor efficacy of SQYC combined with PD-1 inhibitor. Flow cytometry analysis was utilized to investigate the effect of SQYC on the infiltration and immune function of TILs and DCs in the immune microenvironment. Following this, RNA sequencing analysis, seahorse, TEM and immunofluorescence were performed to regulation of SQYC on mitophagy in DCs cells. UPLC-Q-TOF/MS and molecular docking were used to reveal the key blood-entering components of SQYC-regulated PINK1-parkin pathway. The SQYC-containing serum improved the efficacy of sintilimab in MSS CRC organoid model. After combined administration of 11.4 g/kg/day SQYC extract and 5 mg/kg α-PD-1, it was observed that SQYC enhanced the efficacy of PD-1 inhibitor against MSS CRC. Flow cytometry and immunofluorescence analysis revealed an augmented infiltration of tumor-infiltrating lymphocytes (TILs) and an improved antigen presentation function of dendritic cells (DCs). Notably, RNA sequencing analysis demonstrated an evident correlation with mitochondrial function related pathways following SQYC treatment. Mechanistically, SQYC promoted mitophagy in DCs via the PINK1-Parkin pathway, thereby improving mitochondrial quality, energy metabolism, and mitochondrial dynamics. Evaluation of the blood components of SQYC coupled with molecular docking, demonstrated good binding affinity with PINK1/PARKIN/LC3. Our findings highlight SQYC as a promising candidate for improving immunotherapy in MSS CRC, suggesting that targeting PINK1-Parkin in DCs could represent a novel strategy for improving the efficacy of ICIs. Furthermore, it provides new theoretical and scientific underpinnings to enhance the clinical efficacy of immunosuppressants.

Reduced thymic IL-4 impairs negative T cell selection in nonobese diabetic mice.

Type 1 diabetes (T1D) develops spontaneously despite functional antigen presentation machinery in the thymus and a perceptible central tolerance process. We found that intrathymic enrichment with IL-4 fine tunes signaling through the IL-4/IL-13 heteroreceptor (HR) in early thymic progenitors (ETPs), augments negative selection of self-reactive T cells, sustains a diverse T cell repertoire devoid of clones expressing disease-associated T cell receptor (TCR) genes, and protects the nonobese diabetic (NOD) mouse from T1D. Indeed, optimal IL-4 activates STAT transcription factors to program ETP fate decision toward CD11c+CD8α+ dendritic cells (DCs) agile in negative T cell selection and clonal deletion of diabetogenic T cells. However, due to diminished invariant natural killer T (iNKT) 2 cell frequency in the NOD thymus, IL-4 is as suboptimal level, metering STAT activation to program ETP fate decision toward the T cell lineage leading to diminished negative selection, a clonally restricted TCR repertoire, and manifestation of spontaneous T1D. These insights uncover yet another interplay by which IL-4 affects T1D.

Molecular basis for chemokine recognition and activation of XCR1

The X-C motif chemokine receptor XCR1, which selectively binds to the chemokine XCL1, is highly expressed in conventional dendritic cells subtype 1 (cDC1s) and crucial for their activation. Modulating XCR1 signaling in cDC1s could offer novel opportunities in cancer immunotherapy and vaccine development by enhancing the antigen presentation function of cDC1s. To investigate the molecular mechanism of XCL-induced XCR1 signaling, we determined a high-resolution structure of the human XCR1 and Gi complex with an engineered form of XCL1, XCL1 CC3, by cryoelectron microscopy. Through mutagenesis and structural analysis, we elucidated the molecular details for the binding of the N-terminal segment of XCL1 CC3, which is vital for activating XCR1. The unique arrangement within the XCL1 CC3 binding site confers specificity for XCL1 in XCR1. We propose an activation mechanism for XCR1 involving structural alterations of key residues at the bottom of the XCL1 binding pocket. These detailed insights into XCL1 CC3-XCR1 interaction and XCR1 activation pave the way for developing novel XCR1-targeted therapeutics.

The mononuclear phagocyte system obscures the accurate diagnosis of infected joint replacements

IntroductionDiagnosing infected joint replacements relies heavily on assessing the neutrophil response to bacteria. Bacteria form biofilms on joint replacements. Biofilms are sessile bacterial communities encased in a protective extracellular matrix, making them notoriously difficult to culture, remarkably tolerant to antibiotics, and able to evade phagocytosis. Phagocytized bacteria dramatically alter cytokine production and compromise macrophage antigen presentation. We hypothesize that a subset of joint replacements have a dormant infection that suppresses the neutrophil response to bacteria but can be distinguished from uninfected joint replacements by the response of the mononuclear phagocyte system (MPS) within periarticular tissue, synovial fluid, and circulating plasma.MethodsSingle cell RNASeq transcriptomic and OLink proteomic profiling was performed on matched whole blood, synovial fluid, and periarticular tissue samples collected from 4 joint replacements with an active infection and 3 joint replacements without infection as well as 6 joint replacements with a prior infection deemed “infection-free” by the 2018 Musculoskeletal Infection Society criteria (follow-up of 26 ± 3 months).ResultsThe MPS and neutrophil responses differ by infected state; the cellular distribution of the MPS response in the subset of joints with dormant infections resembled actively infected joints (p = 0.843, Chi-square test) but was significantly different from uninfected joints (p < 0.001, Chi-square test) despite the absence of systemic acute phase reactants and recruitment of neutrophils (p < 0.001, t-test). When compared to no infection, the cellular composition of dormant infection was distinct. There was reduction in classically activated M1 macrophages (p < 0.001, Fischer's test) and alternatively activated M2 macrophages coupled with an increase in classical monocytes (p < 0.001, Fischer’s test), myeloid dendritic cells (p < 0.001, Fischer’s test), regulatory T-cells (p < 0.001, Fischer’s test), natural killer cells (p = 0.009, Fischer’s test), and plasmacytoid dendritic cells (p = 0.005, Fischer’s test). Hierarchical cluster analysis and single-cell gene expression revealed that classically M1 and alternatively M2 activated macrophages as well as myeloid dendritic cells can independently distinguish the dormant and uninfected patient populations suggesting that a process that modulates neutrophil recruitment (C1QA, C1QB, LY86, SELL, CXCL5, CCL20, CD14, ITGAM), macrophage polarization (FOSB, JUN), immune checkpoint regulation (IFITM2, IFITM3, CST7, THBS1), and T-cell response (VISIG4, CD28, FYN, LAT2, FCGR3A, CD52) was occurring during dormant infection. Gene set variation analysis suggested that activation of the TNF (FDR < 0.01) and IL17 (FDR < 0.01) pathways may distinguish dormant infections from the active and uninfected populations, while an inactivation of neutrophil extracellular traps (NETs) may be involved in the lack of a clinical response to a dormant infection using established diagnostic criteria. Synovial inflammatory proteomics show an increase in synovial CXCL5 associated with dormant infection (p = 0.011, t-test), suggesting the establishment of a chronic inflammatory state by the MPS during a dormant infection involved in neutrophil inhibition. Plasma inflammatory proteomics also support a chronic inflammatory state (EGF, GZMN, FGF2, PTN, MMP12) during dormant infection that involves a reduction in neutrophil recruitment (CXCL5, p = 0.006, t-test), antigen presentation (LAMP3, p = 0.047, t-test), and T-cell function (CD28, p = 0.045, t-test; CD70, p = 0.002, t-test) that are also seen during the development of bacterial tolerance.DiscussionAll current diagnostic criteria assume each patient can mount the same neutrophil response to an implant-associated infection. However, the state of the MPS is of critical importance to accurate diagnosis of an implant-associated infection. A reduction in neutrophil recruitment and function mediated by the MPS may allow joint replacements with a dormant infection to be mischaracterized as uninfected, thus limiting the prognostic capabilities of all current diagnostic tests.

IMMU-15. CD74/MIF SIGNALING AXIS DISRUPTION IN BONE MARROW-DERIVED MYELOID CELLS DELAYS MALIGNANT PROGRESSION IN A PRECLINICAL MODEL OF GLIOMA

Abstract INTRODUCTION CD74, a chaperone associated with the major histocompatibility complex class II (MHC-II), plays a crucial role in assembling and transporting MHC-II molecules on the cellular surface. Beyond its physiological function in antigen presentation, CD74 is a negative regulator of inflammation, and its dysregulation is associated with inflammatory disorders and cancer. Notably, tumor stem cells release macrophage migration inhibitory factor (MIF) to trigger CD74 immunosuppressive signaling in tumor-infiltrating immune cells, thereby abrogating CD8+ T cell activation and promoting angiogenesis. While CD74 expression is known in dendritic cells, macrophages and B cells, our recent findings reveal its upregulation in immunosuppressive macrophages within the low-grade glioma (LGG) tumor microenvironment, and its negative correlation with the survival of adolescent and young adult patients with LGG. HYPOTHESIS. We hypothesize that inhibiting CD74/MIF in immunosuppressive myeloid cells may affect tumor progression and prevent malignant transformation (MT) to high-grade glioma (HGG). METHODS To test our hypothesis, we isolated bone marrow cells from immunocompetent RCAS n/tv-a LGG bearing animals, differentiated them into bone marrow-derived myeloid cells (BMDMs), silenced CD74 expression, and co-cultured them with primary CD8+T cells. Moreover, we inhibited CD74/MIF signaling in vivo. RESULTS. Deconvolution analysis of tumor-infiltrating immune cells revealed upregulation of CD74 and its network in myeloid cells during LGG compared to HGG. Silencing CD74 in LGG BMDMs in vitro resulted in the downregulation of genes associated with migration, proliferation, and immunosuppression. The co-culture of LGG CD74KD-BMDMs with CD8+ T cells increased the expression of T cell activation genes. In vivo treatment of LGG mice with MIF inhibitors significantly decreased myeloid cell infiltration in the tumor microenvironment (TME) and prolonged survival. CONCLUSIONS These preclinical studies highlight a role for the CD74/MIF signaling axis in glioma and present a novel immunotherapeutic target to modulate the activity of immunosuppressive myeloid cells in order to delay MT.

Functional analysis of antigen presentation by enteric glial cells during intestinal inflammation.

The Enteric Nervous System is composed of a vastly interconnected network of neurons and glial cells that coordinate to regulate homeostatic gut function including intestinal motility, nutrient sensing, and mucosal barrier immunity. Enteric Glial Cells (EGCs) are a heterogeneous cell population located throughout the gastrointestinal tract and have well described roles in regulating intestinal immune responses. Enteric Glial Cells have been suggested to act as nonconventional antigen presenting cells via the Major Histocompatibility Complex II (MHC II), though this has not been confirmed functionally. Here, we investigate the capability of EGCs to present antigen on MHC I and MHC II using in vitro antigen presentation assays performed with primary murine EGC cultures. We found that EGCs are capable of functional antigen presentation on MHC I, including antigen cross-presentation, but are not capable of functional antigen presentation on MHC II. We also determined EGC cell surface MHC I and MHC II expression levels by flow cytometry during intestinal inflammation during Dextran Sodium Sulfate-induced colitis or acute Toxoplasma gondii infection. We found that EGCs upregulate MHC I during acute T. gondii infection and induce low-level MHC II expression. These findings suggest that EGCs may be important in the regulation of CD8+ T cell responses via MHC I mediated antigen (cross) presentation but may not be relevant for MHC II-mediated antigen presentation.

The complex role of immune cells in antigen presentation and regulation of T-cell responses in hepatocellular carcinoma: progress, challenges, and future directions.

Hepatocellular carcinoma (HCC) is a prevalent form of liver cancer that poses significant challenges regarding morbidity and mortality rates. In the context of HCC, immune cells play a vital role, especially concerning the presentation of antigens. This review explores the intricate interactions among immune cells within HCC, focusing on their functions in antigen presentation and the modulation of T-cell responses. We begin by summarizing the strategies that HCC uses to escape immune recognition, emphasizing the delicate equilibrium between immune surveillance and evasion. Next, we investigate the specific functions of various types of immune cells, including dendritic cells, natural killer (NK) cells, and CD8+ T cells, in the process of antigen presentation. We also examine the impact of immune checkpoints, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and the pathways involving programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1), on antigen presentation, while taking into account the clinical significance of checkpoint inhibitors. The review further emphasizes the importance of immune-based therapies, including cancer vaccines and CAR-T cell therapy, in improving antigen presentation. In conclusion, we encapsulate the latest advancements in research, propose future avenues for exploration, and stress the importance of innovative technologies and customized treatment strategies. By thoroughly analyzing the interactions of immune cells throughout the antigen presentation process in HCC, this review provides an up-to-date perspective on the field, setting the stage for new therapeutic approaches.

Clones reactive to apoptotic cells and specific chemical adducts are prevalent among human thymic B cells.

Thymus resident B cells were described more than 40 years ago. In early human life, these cells are found predominantly in the medulla and overwhelmingly display an unswitched IgM+ phenotype. The reactivity of thymic IgM B cells, however, is still unclear. Here, we generated 120 IgM-producing B cell clones from 3 separate thymus specimens obtained from infant, adolescent, and adult donors. Using flow cytometry and a unique high-dimensional ELISA platform, we investigated the clones' reactivity to apoptotic cells as well as to common chemical adducts exposed on modified amino acids and other macromolecules. Regardless of the age, approximately 30-40% of thymic IgM B cells reacted to apoptotic cells. Further, 30-40% displayed reactivity to at least one adduct, including malondialdehyde, Homocysteine, and NEDD 8. Four distinct reactivity patterns were identified through this profiling. Notably, a significant association was observed between reactivity to apoptotic cells, and to one or more adducts, suggesting that the same determinants were recognized in both assays. Additionally, thymic IgM B cells reactive to adducts were more likely to recognize intra-nuclear or intra-cytoplasmic structures in Hep-2 cells as revealed by immunofluorescence staining. Collectively, our findings suggest that thymic IgM B cells actively uptake apoptotic bodies and cellular debris in the medulla by binding specific chemical adducts. This mechanism could underpin their antigen-presenting function and further support their role in T-cell negative selection.

Dynamic glycolytic reprogramming effects on dendritic cells in pancreatic ductal adenocarcinoma

BackgroundPancreatic ductal adenocarcinoma tumors exhibit resistance to chemotherapy, targeted therapies, and even immunotherapy. Dendritic cells use glucose to support their effector functions and play a key role in anti-tumor immunity by promoting cytotoxic CD8+ T cell activity. However, the effects of glucose and lactate levels on dendritic cells in pancreatic ductal adenocarcinoma are unclear. In this study, we aimed to clarify how glucose and lactate can impact the dendritic cell antigen-presenting function and elucidate the relevant mechanisms.MethodsGlycolytic activity and immune cell infiltration in pancreatic ductal adenocarcinoma were evaluated using patient-derived organoids and resected specimens. Cell lines with increased or decreased glycolysis were established from KPC mice. Flow cytometry and single-cell RNA sequencing were used to evaluate the impacts on the tumor microenvironment. The effects of glucose and lactate on the bone marrow-derived dendritic cell antigen-presenting function were detected by flow cytometry.ResultsThe pancreatic ductal adenocarcinoma tumor microenvironment exhibited low glucose and high lactate concentrations from varying levels of glycolytic activity in cancer cells. In mouse transplantation models, tumors with increased glycolysis showed enhanced myeloid-derived suppressor cell infiltration and reduced dendritic cell and CD8+ T cell infiltration, whereas tumors with decreased glycolysis displayed the opposite trends. In three-dimensional co-culture, increased glycolysis in cancer cells suppressed the antigen-presenting function of bone marrow-derived dendritic cells. In addition, low-glucose and high-lactate media inhibited the antigen-presenting and mitochondrial functions of bone marrow-derived dendritic cells.ConclusionsOur study demonstrates the impact of dynamic glycolytic reprogramming on the composition of immune cells in the tumor microenvironment of pancreatic ductal adenocarcinoma, especially on the antigen-presenting function of dendritic cells.

SMAC mimetic drives microglia phenotype and glioblastoma immune microenvironment

Tumor-associated macrophages/microglia (TAMs) are highly plastic and heterogeneous immune cells that can be immune-supportive or tumor-supportive depending of the microenvironment. TAMs are the most abundant immune cells in glioblastoma (GB), and play a key role in immunosuppression. Therefore, TAMs reprogramming toward immune-supportive cells is a promising strategy to overcome immunosuppression. By leveraging scRNAseq human GB databases, we identified that Inhibitor of Apoptosis Proteins (IAP) were expressed by TAMs. To investigate their role in TAMs-related immunosuppression, we antagonized IAP using the central nervous system permeant SMAC mimetic GDC-0152 (SMg). On explants and cultured immune cells isolated from human GB samples, SMg modified TAMs activity. We showed that SMg treatment promoted microglia pro-apoptotic and anti-tumoral function via caspase-3 pro-inflammatory cleavage and the inhibition of tumoroids growth. Then we designed a relevant immunogenic mouse GB model to decipher the spatio-temporal densities, distribution, phenotypes and function of TAMs with or without SMg treatment. We used 3D imaging techniques, a transgenic mouse with fluorescent TAM subsets and mass cytometry. We confirmed that SMg promoted microglia activation, antigen-presenting function and tumor infiltration. In addition, we observed a remodeling of blood vessels, a decrease in anti-inflammatory macrophages and an increased level of monocytes and their mo-DC progeny. This remodeling of the TAM landscape is associated with an increase in CD8 T cell density and activation. Altogether, these results demonstrated that SMg drives the immunosuppressive basal microglia toward an active phenotype with pro-apoptotic and anti-tumoral function and modifies the GB immune landscape. This identifies IAP as targets of choice for a potential mechanism-based therapeutic strategy and SMg as a promising molecule for this application.

Exosomes secreted by podocytes regulate the differentiation of Th17/Treg cells in idiopathic nephrotic syndrome

BackgroundPrevious studies have demonstrated that immune cells release exosomes, which act as antigen-presenting vesicles to activate T cells. In our previous study, we discovered that podocytes, a type of kidney cell, can also exhibit antigen-presenting functions to naïve CD4+ T cells in idiopathic nephrotic syndrome (INS). Building upon these findings, the objective of this study was to investigate whether podocytes can regulate the balance between Th17 and Treg cells through the release of exosomes. MethodsWe co-cultured naïve CD4+ T cells with LPS-treated bone marrow dendritic cells (LPS-BMDC), LPS-treated mouse podocyte clone 5 (LPS-MPC-5), and exosomes derived from LPS-MPC-5 (LPS-EXO). As a control group, naïve CD4+ T cells were cultured with exosomes from untreated MPC-5 (EXO). After 48 h, we analyzed the percentages of Th17 and Treg cells using flow cytometry, measured the concentrations of IL-17A, IL-10, and IL-4 were using ELISA, and examined the expressions of IL-17a, IL-10, RORC, and FOXP3 using RT-qPCR. ResultsWe confirmed the presence of exosomes derived from podocytes based on their morphology, size distribution, concentrations, and the levels of exosomes-specific markers. The percentage of Th17 and Treg cells in the LPS-EXO group was significantly higher than that in the control groups, but lower than in the LPS-MPC-5 group. Furthermore, the ratio of Th17/Treg was relatively higher in the LPS-EXO group compared to the LPS-MPC-5 group. ConclusionThis study indicated further insights into the role of exosomes released from LPS-treated podocytes in regulating the balance between Th17 and Treg cells in INS.

Indirect suppression of CD4 T cell activation through LAG-3-mediated trans-endocytosis of MHC class II

Blockade of immune checkpoint receptors has shown outstanding efficacy for tumor immunotherapy. Promising treatment with anti-lymphocyte-activation gene-3 (LAG-3) has already been recognized as the next efficacious treatment, but there is still limited understanding of the mechanism of LAG-3-mediated immune suppression. Here, utilizing high-resolution molecular imaging, we find a mechanism of CD4 Tcell suppression via LAG-3, in which LAG-3-bound major histocompatibility complex (MHC) class II molecules on antigen-presenting cells (APCs) gather at the central region of an immunological synapse and are trans-endocytosed by Tcell receptor-driven internalization motility toward CD4 and CD8 Tcells expressing LAG-3. Downregulation of MHC class II molecules on APCs thus results in the attenuation of their antigen-presentation function and impairment of CD4 Tcell activation. From these data, anti-LAG-3 treatment is suggested to have potency to directly block the inhibitory signaling via LAG-3 and simultaneously reduce MHC class II expression on APCs by LAG-3-mediated trans-endocytosis for recovery from Tcell exhaustion.

Immunotherapeutic allogeneic dendritic cell and autologous tumor cell fusion vaccine alone or combined with radiotherapy in canine oral malignant melanoma is safe and potentially effective.

Immunotherapy represents a promising breakthrough in cancer management and is being explored in canine melanomas. Dendritic cells (DCs) play a crucial role in priming T-cell-mediated immune reactions through the antigen-presenting function. Combining immunotherapy and radiation therapy may generate more substantial anti-cancer efficacy through immunomodulation. Our research reported a preliminary result of the safety and outcome of a kind of immunotherapy, the allogeneic dendritic cell and autologous tumor cell fusion vaccine, alone or in combination with hypofractionated radiation therapy, in canine oral malignant melanoma. Two groups of dogs with histopathological diagnoses of oral malignant melanoma were recruited. In group 1 (DCRT), dogs received a combination of DC fusion vaccine and radiotherapy. In group 2 (DC), dogs received DC fusion vaccine alone. DC vaccination was given once every 2 weeks for four doses. Radiotherapy was performed weekly for five fractions. Dogs that received carboplatin were retrospectively collected as a control group (group 3). Five dogs were included in group 1 (two stage II, three stage III), 11 in group 2 (three stage I/II, eight stage III/IV), and eight (two stage I/II, six stage III/IV) in the control group. Both DC and DCRT were well-tolerated, with only mild adverse events reported, including mucositis, gastrointestinal discomfort, and injection site reactions. The median progression-free intervals in groups 1, 2, and 3 were 214 (95% CI, NA, due to insufficient data), 100 (95% CI, 27-237), and 42 days (95% CI, NA-170), respectively, which were not significantly different. The 1-year survival rates were 20, 54.5, and 12.5% in groups 1, 2, and 3. Dogs in the DCRT group exhibited significantly higher TGF-β signals than the DC group throughout the treatment course, indicating a possible higher degree of immunosuppression. The manuscript demonstrated the safety of dendritic cell/tumor cell fusion vaccine immunotherapy, alone or in combination with radiotherapy. The results support further expansion of this immunotherapy, modification of combination treatment and protocols, and investigation of combining DC vaccine with other treatment modalities. Preclinical Trials, PCTE0000475.

Galectin-3 induces pathogenic immunosuppressive macrophages through interaction with TREM2 in lung cancer

BackgroundHigh infiltration of tumor-associated macrophages (TAMs) is associated with tumor promotion and immunosuppression. The triggering receptor expressed on myeloid cells 2 (TREM2) is emerged as a key immunosuppressive regulator for TAMs, however, how TREM2-expressing TAMs are recruited and what ligands TREM2 interacts with to mediate immunosuppression is unknown.MethodsFlow cytometry and single-cell RNA sequencing were used to analyze TREM2 expression. Mechanistically, mass spectrometry and immunoprecipitation were employed to identify proteins binding to TREM2. Phagocytosis and co-culture experiments were used to explore the in vitro functions of galectin3-TREM2 pair. Establishment of TREM2f/f-Lyz2-cre mice to validate the role of TREM2 signaling pathway in lung carcinogenesis. GB1107 were further supplemented to validate the therapeutic effect of Galectin3 based on TREM2 signaling regulation.ResultsThis study identified that abundant TREM2+ macrophages were recruited at the intra-tumor site through the CCL2-CCR2 chemotactic axis. Galectin-3 impaired TREM2-mediated phagocytosis and promoted the conversion of TREM2+ macrophages to immunosuppressive TAMs with attenuated antigen presentation and co-stimulatory functions both in vitro both in vivo, and galectin-3 is a potential ligand for TREM2. Genetic and pharmacological blockade of TREM2 and galectin-3 significantly inhibited lung cancer progression in subcutaneous and orthotopic cancer models by remodeling the tumor immune microenvironment.ConclusionOur findings revealed a previously unknown association between galectin-3 and TREM2 in TAMs of lung cancer, and suggested simultaneous inhibition of galectin3 and TREM2 as potent therapeutic approach for lung cancer therapy.Graphical

Interferon regulatory factor 8-driven reprogramming of the immune microenvironment enhances antitumor adaptive immunity and reduces immunosuppression in murine glioblastoma.

Glioblastoma (GBM) has a highly immunosuppressive tumor immune microenvironment (TIME), largely mediated by myeloid-derived suppressor cells (MDSCs). Here, we utilized a retroviral replicating vector (RRV) to deliver Interferon Regulatory Factor 8 (IRF8), a master regulator of type 1 conventional dendritic cell (cDC1) development, in a syngeneic murine GBM model. We hypothesized that RRV-mediated delivery of IRF8 could "reprogram" intratumoral MDSCs into antigen-presenting cells and thereby restore T-cell responses. Effects of RRV-IRF8 on survival and tumor growth kinetics were examined in the SB28 murine GBM model. The immunophenotype was analyzed by flow cytometry and gene expression assays. We assayed functional immunosuppression and antigen presentation by ex vivo T-cell-myeloid co-culture. Intratumoral injection of RRV-IRF8 in mice bearing intracerebral SB28 glioma significantly suppressed tumor growth and prolonged survival. RRV-IRF8 treated tumors exhibited significant enrichment of cDC1s and CD8+ T-cells. Additionally, myeloid cells derived from RRV-IRF8 tumors showed decreased expression of the immunosuppressive markers Arg1 and IDO1 and demonstrated reduced suppression of naïve T-cell proliferation in ex vivo co-culture, compared to controls. Furthermore, DCs from RRV-IRF8 tumors showed increased antigen presentation compared to those from control tumors. In vivo treatment with azidothymidine (AZT), a viral replication inhibitor, showed that IRF8 transduction in both tumor and non-tumor cells is necessary for survival benefit, associated with a reprogrammed, cDC1- and CD8 T-cell-enriched TIME. Our results indicate that reprogramming of glioma-infiltrating myeloid cells by in vivo expression of IRF8 may reduce immunosuppression and enhance antigen presentation, achieving improved tumor control.

Helminth-derived metabolites induce tolerogenic functional, metabolic, and transcriptional signatures in dendritic cells that attenuate experimental colitis.

Inflammatory bowel diseases (IBD) are chronic inflammatory diseases in which abdominal pain, bloody diarrhea, weight loss, and fatigue collectively result in diminished quality of patient life. The disappearance of intestinal helminth infections in Western societies is associated with an increased prevalence of IBD and other immune-mediated inflammatory diseases. Evidence indicates that helminths induce tolerogenic dendritic cells (tolDCs), which promote intestinal tolerance and attenuate intestinal inflammation characteristic of IBD, but the exact mechanism is unclear. Helminth-derived excretory-secretory (HES) products including macromolecules, proteins, and polysaccharides have been shown to modulate the antigen presenting function of DCs with down-stream effects on effector CD4 + T cells. Previous studies indicate that DCs in helminth-infected animals induce tolerance to unrelated antigens and DCs exposed to HES display phenotypic and functional features of tolDCs. Here, we identify that nonpolar metabolites (HnpM) produced by a helminth, the murine gastrointestinal nematode Heligmosomoides polygyrus bakeri (Hpb), induce tolDCs as evidenced by decreased LPS-induced TNF and increased IL-10 secretion and reduced expression of MHC-II, CD86, and CD40. Furthermore, these DCs inhibited OVA-specific CD4 + T cell proliferation and induced CD4 + Foxp3 + regulatory T cells. Adoptive transfer of HnpM-induced tolDCs attenuated DSS-induced intestinal inflammation characteristic of IBD. Mechanistically, HnpM induced metabolic and transcriptional signatures in BMDCs consistent with tolDCs. Collectively, our findings provide groundwork for further investigation into novel mechanisms regulating DC tolerance and the role of helminth secreted metabolites in attenuating intestinal inflammation associated with IBD. Summary Sentence: Metabolites produced by Heligmosomoides polygyrus induce metabolic and transcriptional changes in DCs consistent with tolDCs, and adoptive transfer of these DCs attenuated DSS-induced intestinal inflammation.

Maresin2 negatively regulates DC’s maturation via the MAPK/NF-κB pathway in DCs

ObjectiveTo observe the effects and mechanisms of Maresin2 on the function of DCs(Dendritic cells). MethodThe levels of IL-6, IL-12, TNF-α and IL-1β secreted by BMDCs (Bone marrow-derived Dendritic cells) after Maresin2 treatment were detected by ELISA. At the same time, the expressions of costimulatory molecules CD40 and CD86 on the surface, the ability of phagocytosis of ovalbumin(OVA) antigen, and antigen presentation function in BMDCs were analyzed by flow cytometry. Finally, MAPK and NF-κB pathway signaling phosphorylation in Maresin2-treated BMDCs were detected by western blot. ResultsThe secretion levels of IL-6, IL-12, TNF-α and IL-1β were significantly decreased in the Maresin2 treatment group after LPS treatment (P < 0.05). The expression levels of CD86 and CD40 were significantly decreased after Maresin2 treatment (P < 0.05). Maresin2 enhanced the phagocytosis ability of ovalbumin(OVA) (P < 0.05), but the ability of antigen presentation of BMDCs with the treatment of Maresin2 changed slightly (P > 0.05). Phosphorylation of p38, JNK, p65, ikka/β and ERK peaked at 15 min in the LPS group, while phosphorylation of p-p38 and p-ERK weakened 30 min and 60 min after treatment with Maresin2. ConclusionsMaresin2 inhibits inflammatory cytokine secretion but enhances phagocytosis via the MAPK/NF-κB pathway in BMDCs, which may contribute to negatively regulating inflammation.