Lower Expression Of CD40 Research Articles

Dual novel variants in CD40 leading to hyper IgM syndrome: a case report of a school-aged female with new-onset recurrent pneumonia

Introduction: Hyper IgM (HIGM) syndrome is an inborn error of immunity (IEI) that occurs due to defects in immunoglobulin class switch recombination (Ig-CSR). HIGM syndrome typically presents with recurrent infections in early childhood, and is often characterized on investigation with decreased IgG, IgA, and IgE titres, alongside normal or elevated IgM. A common cause of HIGM syndrome is a disruption to the CD40-CD40 ligand (CD40L) interaction that triggers Ig-CSR, of which variants in CD40 are much rarer than those in CD40L. We present a case of an 11-year-old female with HIGM syndrome caused by two novel variants of in the CD40 gene. Aim: To describe a case report of an eleven-year-old female with HIGM syndrome presenting with recurrent pneumonia. Methods: Data was collected retrospectively from the patient’s medical records. Laboratory investigations included quantitative immunoglobulins, quantitative B and T cell subsets, genetic testing using a primary immunodeficiency panel, and a functional assay for CD40 expression. Results: The proband is an 11-year-old female, who presented with recurrent pneumonia, otitis, and septic arthritis. Investigations revealed neutropenia, low IgA, elevated IgM and normal IgG, along with absent vaccine responses. She was identified to harbour two novel variants in CD40: an intronic variant c.52-13A>G p.(?) and a missense variant c.466T>C p.(Ser156Pro). Functional assay indicated low expression of CD40 compared to healthy control, confirming the diagnosis of CD40 deficiency. Conclusion: Class switch defects, such as CD40 deficiency, are rare but significant diagnoses within the spectrum of IEI. This case demonstrates that despite the absence of some clinical red flags for immunodeficiency in infancy, IEIs remain an important consideration in pediatric patients regardless of age. Increasing clinical awareness of IEI will lead to earlier diagnoses, initiation of appropriate treatment, and prevention of potential complications. Statement of novelty: We describe a patient with a late presentation of hyper IgM syndrome due to two novel variants in the CD40 gene, thus expanding the spectrum of CD40 gene variants.

IFNγ insufficiency during mouse intra-vaginal Chlamydia trachomatis infection exacerbates alternative activation in macrophages with compromised CD40 functions

Chlamydia trachomatis (C.tr), an obligate intracellular pathogen, causes asymptomatic genital infections in women and is a leading cause of preventable blindness. We have developed in vivo mouse models of acute and chronic C. trachomatis genital infection to explore the significance of macrophage-directed response in mediating immune activation/suppression. Our findings reveal that during chronic and repeated C. trachomatis infections, Th1 response is abated while Treg response is enhanced. Additionally, an increase in exhaustion (PD1, CTLA4) and anergic (Klrg3, Tim3) T cell markers is observed during chronic infection. We have also observed that M2 macrophages with low CD40 expression promote Th2 and Treg differentiation leading to sustained C. trachomatis genital infection. Macrophages infected with C. trachomatis or treated with supernatant of infected epithelial cells drive them to an M2 phenotype. C. trachomatis infection prevents the increase in CD40 expression as observed in western blots and flow cytometric analysis. Insufficient IFNγ, as observed during chronic infection, leads to incomplete clearance of bacteria and poor immune activation. C. trachomatis decapacitates IFNγ responsiveness in macrophages via hampering IFNγRI and IFNγRII expression which can be correlated with poor expression of MHC-II, CD40, iNOS and NO release even following IFNγ supplementation. M2 macrophages during C. trachomatis infection express low CD40 rendering immunosuppressive, Th2 and Treg differentiation which could not be reverted even by IFNγ supplementation. The alternative macrophages also harbour high bacterial load and are poor responders to IFNγ, thus promoting immunosuppression. In summary, C. trachomatis modulates the innate immune cells, attenuating the anti-chlamydial functions of T cells in a manner that involves decreased CD40 expression on macrophages.

Single-Cell Metabolic Profiling Integrated with Extracellular Vesicle Analysis Reveals Novel Metabolic Vulnerabilities and Prognostic Biomarkers in Acute Myeloid Leukemia

Introduction Acute myeloid leukemia (AML) is an aggressive disease for which less invasive tools are needed to explore disease dynamics. Changes in cell metabolism and metabolic adaptation are hallmark features for AML, thus emerging as promising therapeutic targets. However, it is still poorly elucidated whether and which extrinsic microenvironment signals may regulate the metabolic reprogramming occurring in AML. In this regard, Extracellular Vesicles (EVs) represent a promising tool for non-invasive liquid biopsy and may reveal a novel role in energy metabolism as well as clinically relevant biomarkers for AML. Along with EV profiling from peripheral blood (PB), we mapped the metabolic signature of leukemic stem cells (LSCs) and immune cell subsets to identify metabolic vulnerabilities and novel prognostic biomarkers. Methods PB (and paired bone marrow) were collected from AML patients at diagnosis (n=98) and healthy donors (HD, n=12). EVs were purified from platelet-free PB plasma of AML patients by size-exclusion chromatography followed by ultrafiltration. We have submitted all relevant data of our EV experiments to the EV-TRACK knowledgebase (EV-TRACK ID: EV230004). MACSPlex Exosome Kit was used for screening up to 37 surface EV markers. Western blot analysis was also performed. Energy cell metabolism was explored by Single Cell ENergetic metabolism by profilIng Translation inHibition (SCENITH TM) in LSC-like cells (CD34 +CD38 low/-)and immune cell subsets (CD3 +/CD4 +/CD8 +/T regulatory cells) using conventional/spectral flow-cytometry. Results Here, we developed a novel method exploiting both LSCs and EVs from AML patients using fresh whole blood for metabolic exploration. Firstly, we observed that LSC-like cells display low reactive oxygen species (ROS) levels with both high glutathione (GSH, as antioxidant molecule) levels and mitochondrial functionality suggesting a more resistant phenotype. Consistently, poor clinical outcomes were experienced by AML patients treated with conventional chemotherapy and with high GSH levels and mitochondrial potential in LSC-like cells (log-rank p=0.04). We also found high dependence on glucose and a preferential skewing toward glycolysis in LSC-like cells revealing a distinct metabolic status for LSCs in circulation. However, according to European LeukemiaNet (ELN) 2022 risk classification, a more prominent mitochondrial dependence on LSC-like cells was reported for intermediate- or adverse-risk AML patients revealing a prognostic relevance. By contrast, exploring the immunometabolic reprogramming in circulation, we revealed a significant decrease in glucose dependence for immune cells (CD4 + and CD8 + T cells) in comparison to LSCs proving the presence of a complex metabolic network in AML. Interestingly, we investigated the potential metabolic effects of EVs on LSCs. Indeed, CD34 + LSC-like cells co-cultured with circulating EVs enhanced their GSH levels and mitochondrial functionality towards a more aggressive phenotype. Accordingly, we discovered the presence of the antioxidant enzyme, glutathione peroxidases 3 (GPx-3), in AML EVs. Then, we profiled the surface proteins of isolated EVs to detect their cell origins and provide a reference map for clinical prognosis. We found that circulating AML EVs were significantly enriched in CD4 (helper T cell marker), CD14 (monocyte marker), CD40 (B-cell associated marker), CD44 and CD133-1 (stem cell markers), CD105 (stromal cell marker) and HLA-II (antigen-presenting cell marker) compared to HD EVs. In particular, we found that intermediate-risk AML patients showed a strong depletion in the expression of EV markers including T cell markers (CD2 and CD8) and mesenchymal markers (CD49e and CD146) in comparison to favorable and adverse-risk patients. Interestingly, AML patients who had been treated not intensively and showed low expression of CD40 (HR=0.23, 95% CI, 0.05−0,99, p=0.04) or CD62P (platelet activation marker, HR=0.24, 95% CI, 0.05−1.02, p=0.05) on EVs experienced poor outcomes suggesting that dedifferentiated phenotype on EVs might be associated with worse prognosis. Conclusion Overall, towards a new redefined ‘metabolic’ stratification for AML patients, we identified novel prognostic biomarkers for AML patients that might reveal novel metabolic vulnerabilities by exploiting in parallel single-cell metabolic profile and EV-based liquid biopsy.

Sitagliptin Induces Tolerogenic Human Dendritic Cells

Sitagliptin, an anti-diabetic drug, is a dipeptidyl peptidase (DPP)-4/CD26 inhibitor with additional anti-inflammatory and immunomodulatory properties. In this study, we investigated for the first time the effect of sitagliptin on the differentiation and functions of human dendritic cells generated from monocytes (MoDCs) for 4 days using the standard GM-CSF/IL-4 procedure. LPS/IFN-γ treatment for an additional 24 h was used for maturation induction of MoDCs. Sitagliptin was added at the highest non-cytotoxic concentration (500 µg/mL) either at the beginning (sita 0d protocol) or after MoDC differentiation (sita 4d protocol). Sitagliptin impaired differentiation and maturation of MoDCs as judged with the lower expression of CD40, CD83, CD86, NLRP3, and HLA-DR, retention of CD14 expression, and inhibited production of IL-β, IL-12p70, IL-23, and IL-27. In contrast, the expression of CD26, tolerogenic DC markers (ILT4 and IDO1), and production of immunoregulatory cytokines (IL-10 and TGF-β) were increased. Generally, the sita 0d protocol was more efficient. Sitagliptin-treated MoDCs were poorer allostimulators of T-cells in MoDC/T-cell co-culture and inhibited Th1 and Th17 but augmented Th2 and Treg responses. Tolerogenic properties of sitagliptin-treated MoDCs were additionally confirmed by an increased frequency of CD4+CD25+CD127- FoxP3+ Tregs and Tr1 cells (CD4+IL-10+FoxP3-) in MoDC/T-cell co-culture. The differentiation of IL-10+ and TGF-β+ Tregs depended on the sitagliptin protocol used. A Western blot analysis showed that sitagliptin inhibited p65 expression of NF-kB and p38MAPK during the maturation of MoDCs. In conclusion, sitagliptin induces differentiation of tolerogenic DCs, and the effect is important when considering sitagliptin for treating autoimmune diseases and allotransplant rejection.

Chlamydia trachomatisinfection renders M2 generation to mediated immunosuppression.

Abstract Chlamydia trachomatis (C.tr) cause asymptomatic genital infections in women and is also a leading cause of preventable blindness. Limited mouse model of chronic C.tr infection are available to study the host immune response. We have developed BALB/c mice models of acute and chronic infections for C. trachomatisto explore the significance of macrophage-directed response in mediating immune activation/suppression. We observed that chronic and repeated infections accompanied abbrogated IFN-g and promoted enhanced TGF-β and IL-10 secretion. The signs of T cell exhaustion and anergy were also indicated during chronic and secondary infection. This skewed T cell response was established to be the regulated by alternatively-activated macrophages with low CD40 expression leading to sustained C. trachomatis genital infection. Macrophages under the influence of C. trachomatis infection or its secretome demonstrate an M2-macrophage subset phenotype which responded poorly to IFN-g owing to decreased IFNg-RI and IFNg-RII expression which correlated with decreased expression/release of MHC-II, CD40, iNOS and NO even following IFN-g treatment. Alternatively-activated M2 macrophages with low CD40 expression harbored high bacterial load and rendered the generation of immunosuppressive Th2 and Treg cells. Thus, C. trachomatis modulate the innate immune cells attenuating the anti-chlamydial functions of T cells in a manner that involves alleviated CD40 expression on macrophages.

The Expression of CD40/CD40L in MM Patients and Its Significance to the Prognosis of MM Patients

To explore the expression of CD40/CD40L in multiple myeloma(MM) patients and its influence on prognosis. Thirty patients with MM treated in Cangzhou People's Hospital from May 2016 to June 2017 were selected and divided into MM group, then 30 healthy people with a physical examination in our hospital at the same time were selected as the normal group. The serum CD40/CD40L levels of the patients in the two groups was detected by flow cytometry, and its correlation with the lymphocyte population, pathological grade and prognostic significance of MM patients was anaysis. The expression of CD40 in serum of the patients in MM group was significantly higher than those in normal group (P<0.05). The expression of CD40L in serum of the patients in MM group showed no significant difference as compared with those in normal group (P>0.05). The levels of CD40 and CD40L in the patients before and after chemotherapy showed no difference(P>0.05). The levels of Ts and NK cells in the patients of MM group were lower than those in normal group (P<0.05). The proportion of total B lymphocytes, Th and Th/Ts cells between the two groups showed no significant difference (P>0.05). The CD40 level was correlated with the serum total B lymphocyte level of the patients in MM group (r=0.877, P=0.005). There was a correlation with CD40L and Th cells in the serum of MM patients (r=-0.783, P=0.035). The expression of serum CD40 in the patients at phase III-IV was higher than those of the patients at phase I-II, the levels of serum CD40L in MM patients at different periods showed no significant difference(P>0.05). The survival rate of MM patients with high CD40 expression was lower than that of MM patients with low CD40 expression (χ2=1.639, P=0.201). The high level CD40 was the main factor affecting the prognosis of MM patients (95%CI: 1.156-4.125). The increasing of CD40 level in MM patients is related to the pathological grade of the patients. Chemotherapy can reduce the level of CD40. The increasing of CD40 is an important factor for the poor prognosis of MM patients. CD40L level is not meaningful for MM treatment and prognosis.

Effects of Ibrutinib on Metabolic Alterations and Micro-Environmental Signalling in Chronic Lymphocytic Leukaemia

Introduction. Altered metabolism is one of the hallmarks of cancer. CLL cells circulate between peripheral blood (PB) and lymph nodes (LN) which necessitates high metabolic plasticity. In LN, CLL cells receive proliferative and pro-survival signals from surrounding cells, and become metabolically activated. However, detailed insight into the altered metabolism of LN CLL and how this may be related to therapeutic responses is lacking. As it is technically difficult to obtain direct insight into CLL LN metabolism, we have applied a two-tiered strategy. By using PB samples taken from patients before/after treatment with the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib (IBR), which drives CLL cells out of the LN, combined with in vitro re-stimulation of TME signals, we indirectly mapped the metabolism of CLL in their TME, as well as the effects of IBR treatment. We hypothesized that the overlapping/distinct metabolites affected by IBR and in vitro stimulations would reflect the actual CLL metabolism in LN. Methods. PB samples were obtained from 7 CLL patients before or after 3 months of ibrutinib treatment. These paired samples were in vitro stimulated via CD40 and B cell receptor (BCR), which are potential key signals within the tumour microenvironment (TME). Seahorse extracellular flux (ECF) analyses, expression of activation markers (CD95, pS6 by FACS), RNA was isolated for expression of Myc (major driver of metabolic reprogramming) and its target genes, and metabolomics by mass-spec was performed. Results. ECF analyses showed that in comparison to BCR stimulated PB CLL cells, stimulation by CD40 resulted in a high increase of oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). A prominent effect on OXPHOS and glycolytic activity was confirmed in direct LN samples, and indirectly by marker analyses in LN emigrants using CXCR4/CD5 staining [1]. Subsequent metabolomics analyses showed that metabolic reprogramming following CD40 or BCR stimulation revealed both shared and distinct responses. The affected metabolic pathways, predicted by significantly changed metabolites, were compared in a pairwise fashion; upregulated by CD40 and BCR but downregulated by IBR, respectively. The results demonstrated 5 upregulated pre-defined pathways (KEGG) by both CD40 and BCR triggering: purine metabolism, Warburg effect, lysine degradation, glucose-alanine cycle and glutamate metabolism. In contrast, the following pathways indicated the two signals had distinct functions on regulating metabolism: CD40 signalling mostly regulates amino acid metabolism, tricarboxylic acid cycle (TCA) and mitochondrial metabolism related to oxidative phosphorylation (OXPHOS) and energy production. BCR signalling mainly involves glucose and glycerol metabolism, which are usually related to biosynthesis. CLL cells from IBR-treated patients showed enhanced BCR responsiveness, in line with the increased in surface IgM expression upon IBR [2]. In contrast, IBR treatment suppressed in vitro CD40 activation, which was accompanied by a lower CD40 expression. Metabolomics analyses also demonstrated that CD40 responses decreased but BCR response increased after IBR. Additionally, analyses of Myc and its target genes showed that they are induced after BCR as well as CD40 stimulation. Effects of IBR on Myc (target) expression were variable for BCR and reduced for CD40 stimulation. Conclusions. In vivo IBR treatment suppresses CD40 expression and activation and enhances BCR responsiveness. Metabolic changes of CLL in LN are recapitulated by these two signals, while IBR treatment shows opposite effects, together providing indirect insight into the LN metabolism. In LN, CD40 may play a prominent role to enhance most of the key metabolic pathways, particularly OXPHOS. This is the first study to describe the metabolic network of CLL cells in LN, and the long-term effects of IBR may yield new clues to therapy response and resistance.

Glutathione-S-transferase of Trichinella spiralis regulates maturation and function of dendritic cells.

Immunomodulation by molecules from Trichinella spiralis (T. spiralis) has been widely reported. Glutathione-S-transferase (GST) is a major immune-modulator of the family of detoxification enzymes. Dendritic cells (DCs) are an important target for the regulation of the immune response by T. spiralis. In this study, the recombinant GST of T. spiralis (rTs-GST) was expressed and purified. rTs-GST induced low CD40 expression and moderate CD80, CD86 and MHC-II expressions and inhibited the increase of CD40, CD80 and CD86 on DCs induced by LPS. We showed that rTs-GST decreased the LPS-induced elevated level of pro-inflammatory cytokines of DCs and enhanced the level of regulatory cytokines IL-10 and TGF-β. Furthermore, co-culture of DCs and CD4+ T cells demonstrated that rTs-GST-treated DCs suppressed the proliferation of OVA-specific CD4+ T cells and increased the population of regulatory T cells (Tregs). rTs-GST-treated DCs induced a higher level of IL-4, IL-10 and TGF-β, but inhibited the level of IFN-γ. This indicates that rTs-GST-pulsed DCs induce both Th2-type responses and Tregs. These findings contribute to the current understanding of the immunomodulation of Ts-GST on cellular response and immunomodulation of T. spiralis.

Adipose-derived mesenchymal stem cells attenuate rejection in a rat lung transplantation model

BackgroundImmunosuppression following lung transplantation is a key aspect to the graft's survival. However, the well-known complications that are caused by immunosuppressive regimens present an opportunity to study ways to minimize the usage of these drugs. Recently, a promising discovery has been made pertaining to the immunomodulatory effects of adipose tissue–derived mesenchymal stem cells (ADMSCs) through their secretion of hepatocyte growth factor. In the hopes of mitigating the adverse effects of standard immunosuppressive regimens, our study aims to investigate the effects of ADMSCs on the immune response utilizing a rat lung transplantation model. MethodsEach rat's own ADMSCs were intravenously administered immediately after orthotopic left lung transplantation. The experimental subjects were divided into four groups: 1) control group (group C) was administered no treatment following transplantation; 2) ADMSC group (group A), administered a single intravenous injection of ADMSCs following transplantation; 3) tacrolimus group (group T), administered tacrolimus (0.5 mg/kg) every 24 h following transplantation; and 4) ADMSC and tacrolimus group (AT group) administered a single intravenous injection of ADMSCs in combination with tacrolimus every 24 h following transplantation. ResultsThe histologically proven rejection grade in group AT was significantly lower than that in group T. The serum levels of hepatocyte growth factor and the expression of cMet in group AT accompanied by low CD40 expression were also significantly higher than those of the lung grafts of group T. ConclusionsThese results suggest that co-administration of ADMSCs with tacrolimus is a beneficial therapeutic approach in lung transplantation.

Activated macrophages control human adipocyte mitochondrial bioenergetics via secreted factors

ObjectiveObesity-associated WAT inflammation is characterized by the accumulation and local activation of macrophages (MΦs), and recent data from mouse studies suggest that macrophages are modifiers of adipocyte energy metabolism and mitochondrial function. As mitochondrial dysfunction has been associated with obesity and the metabolic syndrome in humans, herein we aimed to delineate how human macrophages may affect energy metabolism of white adipocytes. MethodsHuman adipose tissue gene expression analysis for markers of macrophage activation and tissue inflammation (CD11c, CD40, CD163, CD206, CD80, MCP1, TNFα) in relationship to mitochondrial complex I (NDUFB8) and complex III (UQCRC2) was performed on subcutaneous WAT of 24 women (BMI 20–61 kg/m2). Guided by these results, the impact of secreted factors of LPS/IFNγ- and IL10/TGFβ-activated human macrophages (THP1, primary blood-derived) on mitochondrial function in human subcutaneous white adipocytes (SGBS, primary) was determined by extracellular flux analysis (Seahorse technology) and gene/protein expression. ResultsStepwise regression analysis of human WAT gene expression data revealed that a linear combination of CD40 and CD163 was the strongest predictor for mitochondrial complex I (NDUFB8) and complex III (UQCRC2) levels, independent of BMI. IL10/TGFβ-activated MΦs displayed high CD163 and low CD40 expression and secreted factors that decreased UQCRC2 gene/protein expression and ATP-linked respiration in human white adipocytes. In contrast, LPS/IFNγ-activated MΦs showed high CD40 and low CD163 expression and secreted factors that enhanced adipocyte mitochondrial activity resulting in a total difference of 37% in ATP-linked respiration of white adipocytes (p = 0.0024) when comparing the effect of LPS/IFNγ- vs IL10/TGFβ-activated MΦs. ConclusionOur data demonstrate that macrophages modulate human adipocyte energy metabolism via an activation-dependent paracrine mechanism.

Expression of CD40 is a positive prognostic factor of diffuse large B-cell lymphoma treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone).

ObjectivesThe objective of this study was to investigate the expression level of CD40 and its role in the prognosis of patients with diffuse large B-cell lymphoma (DLBCL) who were treated with rituximab-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone).Design and methodsThe immunohistochemical expressions of CD40 in 186 well-characterized DLBCL patients were evaluated by tissue microarrays, thereby revealing the relationship of the molecule CD40 with known tumor, patient-related variables, and survival rates.ResultsThe results showed that CD40 expressions were not statistically different between the germinal center B-cell-like (GCB) type and the non-GCB type. We also analyzed the relationships of CD40 expression with overall survival (OS) and progression-free survival (PFS) in DLBCL patients who were uniformly treated with R-CHOP. A low expression of CD40 compared to high expression is related to poor OS and PFS.ConclusionOur findings indicate that the CD40 level at onset acts as an independent prognostic predictor of DLBCL patients treated with R-CHOP.

Defining the phenotype and transcriptome of IgG3+ B cells

Abstract Recent studies suggest that highly polyfunctional non-neutralizing HIV-specific IgG3 antibodies are associated with protection from HIV infection in the RV144 HIV vaccine trial. While it is well established that IgG3 Abs can drive a wide range of Fc-mediated innate effector functions, it remains unclear whether intrinsic factors are important for selection and maintenance of IgG3-secreting B cells and what extrinsic signals preferentially induce IgG3 class-switch. We hypothesized that (1) IgG3+ B cells will generally express enhanced levels of activation-associated surface proteins and markers important for interactions with T cells as compared to IgG1+ B cells and (2) IgG3+ B cells will have a unique transcriptome that helps prevent downstream class switch recombination. Our initial flow cytometry and RNA-sequencing (RNA-seq) analyses have focused on comparing IgG3+ memory B cells to IgM+ and IgG1+ memory B cells in HIV negative donors. We have found that IgG3+ B cells have higher expression of CD80 and CD95, but lower expression of CD40, than IgG1+ B cells. Preliminary bulk RNA-seq analyses similarly suggest that IgG3+ B cells have a unique transcriptome, with distinct expression of genes involved in transcriptional regulation, nucleosome assembly and chromatin organization. Interestingly, IgM+ and IgG1+ memory B cells share an overlapping transcriptional regulation cluster that may exist to prevent class-switch to IgG3 (from IgM) and induce class-switch to IgG1 (from IgG3). We are currently investigating the heterogeneity of resting and stimulated IgG3+ memory B cells at the single-cell level to better understand why some, but not all, IgG3+ memory B cells retain expression of IgG3.

Anti-Tumor Necrosis Factor Therapy Restores Peripheral Blood B-cell Subsets and CD40 Expression in Inflammatory Bowel Diseases.

Anti-tumor necrosis factor (TNF) therapy has become a standard therapy for severe inflammatory bowel diseases (IBD), but its effect on B lymphocytes is largely unexplored. In this study we investigated peripheral blood B cells, B-cell subsets, and CD40 expression in patients with IBD before and during anti-TNF therapy with infliximab (IFX). Blood was taken from healthy controls (n = 52) and patients with active IBD before (n = 46) and/or during anti-TNF therapy (n = 55). B-cell markers were detected by immunofluorescent staining and FACS analysis. Patients were classified as responders or nonresponders to anti-TNF therapy. We found a numerical deficiency of circulating CD19 B cells, a lower activation state (CD40 expression) and lower proportions of CD5 B cells and IgMIgDCD27 preswitched memory cells among B cells in active patients with IBD before IFX therapy compared with healthy controls. IFX treatment increased CD19 B-cell numbers as well as the proportions of named B-cell subsets in responders but not in nonresponders. IFX more effectively upregulated CD40 expression in responders than in nonresponders. Restoration of B cells correlated with the biological response to therapy (C-reactive protein). Trough serum levels of IFX correlated with the number of B cells during therapy. A lower number of circulating B cells, a low CD40 expression, and a decrease in the proportion of CD5 and in the preswitched memory subset characterize active IBD. Restoration of these abnormalities correlates with the clinical response to anti-TNF therapy. The mechanism for this effect on B cells should be further explored.

Inhaled house dust programs pulmonary dendritic cells to promote type 2 T-cell responses by an indirect mechanism.

The induction of allergen-specific T helper 2 (Th2) cells by lung dendritic cells (DCs) is a critical step in allergic asthma development. Airway delivery of purified allergens or microbial products can promote Th2 priming by lung DCs, but how environmentally relevant quantities and combinations of these factors affect lung DC function is unclear. Here, we investigated the ability of house dust extract (HDE), which contains a mixture of environmental adjuvants, to prime Th2 responses against an innocuous inhaled antigen. Inhalational exposure to HDE conditioned lung conventional DCs, but not monocyte-derived DCs, to induce antigen-specific Th2 differentiation. Conditioning of DCs by HDE was independent of Toll-like receptor 4 signaling, indicating that environmental endotoxin is dispensable for programming DCs to induce Th2 responses. DCs directly treated with HDE underwent maturation but were poor stimulators of Th2 differentiation. In contrast, DCs treated with bronchoalveolar lavage fluid (BALF) from HDE-exposed mice induced robust Th2 differentiation. DC conditioning by BALF was independent of the proallergic cytokines IL-25, IL-33, and thymic stromal lymphopoietin. BALF treatment of DCs resulted in upregulation of CD80 but low expression of CD40, CD86, and IL-12p40, which was associated with Th2 induction. These findings support a model whereby environmental adjuvants in house dust indirectly program DCs to prime Th2 responses by triggering the release of endogenous soluble factor(s) by airway cells. Identifying these factors could lead to novel therapeutic targets for allergic asthma.

PTU-140 Intrahepatic Tregs Are Plastic But Functional And Biliary Epithelial Cells Support Their Fate

IntroductionRegulatory T cells (Tregs) are crucial in maintaining peripheral tolerance. Tregs control T effector CD8, CD4, Th1 cells along with other immune cells to maintain hepatic tolerance. They are implicated...

TLR-CD40 Cross-Talk in Anti-Leishmanial Immune Response.

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) and activate innate immune cells to induce cytokines and co-stimulatory molecules such as CD40 and to enhance antigen presentation to T cells (1) that, upon activation, can either eliminate or support the pathogen (2). Herein, we propose that this duality in TLR functions results from their cross-talk with CD40. While all TLRs enhance CD40 expression, CD40 augments the expression of only TLR9 (3). As both CD40 and TLR9 induce expression of IL-12, a cytokine that induces the IFN-γ secreting Th1 cell differentiation (4), the CD40–TLR9 cross-regulation implies a positive feedback loop. By contrast, TLR1–TLR2 heterodimer down-regulates TLR9 expression (5) and antagonizes the development of Th1 response but favors the differentiation of regulatory T (T-reg) cells (Pandey et al., unpublished observation). Low CD40 expression levels in dendritic cells also promote T-reg cell differentiation (6). This duality can emerge from the sharing of signaling molecules. CD40 induces TRAF6-mediated, ERK-1/2-dependent IL-10 (7), which can inhibit the TLR-induced p38-MAPK activation and IL-12 production, antagonizing Th1 development. CD40-induced TRAF3-dependent p38-MAPK activation (7) can synergize with the TLR-activated p38-MAPK-dependent IL-12 production and Th1 differentiation. Using Leishmania infection, we show that the TLR–CD40 cross-talk can induce contrasting anti-leishmanial immune responses. Leishmania, a protozoan parasite, lives in macrophages. Leishmania expresses lipophosphoglycan (LPG), proteoglycans, flagellin, and profilin for possible recognition by the host cell-expressed TLRs. Recognition of the Leishmania-expressed PAMPs results in differential immune responses, which can either reduce or exacerbate Leishmania infection. As TLRs modulate the expression of CD40, a co-stimulatory molecule whose expression levels modulate anti-leishmanial T cell responses, we propose that TLR–CD40 cross-talk significantly regulate the outcome of an anti-leishmanial immune response.

Low CD40 Expression Levels inLeishmaniaInfantum-Infected Bone Marrow Dendritic Cells Evoke Regulatory Responses by Down-Regulating Interleukin-12 Production: Role of ERK1/2

Dendritic cells (DCs) play a pivotal role in promoting resistance to leishmaniasis, both by activating CD4+T cells and endorsing their differentiation into Th1 cells by producing interleukin (IL)-12. High level of IL-12 production, a decisive component of the DC maturation, requires not only microbial stimuli but also strong CD40-CD40L interactions. Until now, the mechanisms by which Leishmania (L.) infantum parasites affect DC functional maturation and consequently T cell polarization are not fully understood. In the present study, we investigated the response that is elicited when L. infantum promastigote-infected bone marrow-derived DCs (BM-DCs) to CD40 engagement and this way mimicking DC-T cells interactions at the early stages of infection. We found that L. infantum promastigotes-infected BM-DCs following CD40 engagement were capable of inducing significant amounts of TNF-α and IL-10, whereas IL-12 production remained unaffected compared to infected untreated cells. Interestingly, infected BM-DCs did not up-regulate CD40 surface expression. On the other hand, BM-DC stimulation with soluble Leishmania antigen (SLA) resulted not only in significant increase of co-stimulatory molecule expression but also IL-12 and IL-10 production. CD40 engagement on L. infantum-infected BM-DCs sustained ERK1/2 activation induced by the parasite alone. Inhibition of ERK1/2 activation with the use of PD98059 inhibitor prior to CD40 engagement on L. infantum-infected BM-DCs resulted in significant up-regulation of p38 MAPK phosphorylation and IL-12 production, whereas it did not affect TNF-α and IL-10 production. These findings suggest that L. infantum has evolved specific strategies to avoid efficient DC-T cell interactions by suppressing CD40 expression and consequently leading CD40 signaling pathways to ERK1/2 activation.

DNA and protein co-administration induces tolerogenic dendritic cells through DC-SIGN mediated negative signals

We previously demonstrated that DNA and protein co-administration induced differentiation of immature dendritic cells (iDCs) into CD11c+CD40lowIL-10+ regulatory DCs (DCregs) via the caveolin-1 (Cav-1) -mediated signal pathway. Here, we demonstrate that production of IL-10 and the low expression of CD40 play a critical role in the subsequent induction of regulatory T cells (Tregs) by the DCregs. We observed that DNA and protein were co-localized with DC-SIGN in caveolae and early lysosomes in the treated DCs, as indicated by co-localization with Cav-1 and EEA-1 compartment markers. DNA and protein also co-localized with LAMP-2. Gene-array analysis of gene expression showed that more than a thousand genes were significantly changed by the DC co-treatment with DNA + protein compared with controls. Notably, the level of DC-SIGN expression was dramatically upregulated in pOVA + OVA co-treated DCs. The expression levels of Rho and Rho GNEF, the down-stream molecules of DC-SIGN mediated signal pathway, were also greatly upregulated. Further, the level of TLR9, the traditional DNA receptor, was significantly downregulated. These results suggest that DC-SIGN as the potential receptor for DNA and protein might trigger the negative pathway to contribute the induction of DCreg combining with Cav-1 mediated negative signal pathway.

The protective effects of CD4+ CD25+ Treg cell on the allograft after infusion of dendritic cells with low expression of CD40 from donor in mouse heart transplantation

Objective To explore the effects of CD4+CD25+Treg cell on the allograft after infusion of dendritic cells (DCs) with low expression of CD40 from donor in mouse heart transplantation.Methods In vitro,mouse bone marrow-derived DCs were infected by CD40-RNAi lentiviral vector,and tolerogenic DCs (Tol-DCs) with low expression of CD40 were prepared.A heterotopic abdominal heart transplantation model was established in mice,and the other three groups that were control group,noninfected DC group and lentivirus infected DC group were designed correspondingly.Cardiac allograft survival time was recorded and pathological grading for acute rejection was assessed on the 7 d after heterotopic abdominal heart transplantation.Concentrations of CD4+CD25+Treg cells in peripheral blood were analyzed before and after transplantation by flow cytometry.Results After 48 h infection of DCs by CD40-RNAi lentiviral vector in vitro,the expression of CD40 mRNA was down-regulated significantly,whose inhibition rate was 80.9％.The expression of CD40 was decreased from 74.37％ ±4.08％ to 40.07％ ± 4.03％ (P＜0.05) after 48 h infection.Compared with the control group and the noninfected DC group,the cardiac allograft survival time was significantly prolonged in the CD40-RNAi lentivirus infected DC group,which was (14 ± 4) d(P＜0.01) ; concentrations of CD4+CD25+Treg cells in peripheral blood were increased both on the 3 d and the 7 d after transplantation (P＜0.05) ; the pathological grading for acute rejection was decreased on the 7 d after transplantation (P＜0.05).Conclusion The CD4+CD25+Treg cell in peripheral blood was protective to cardiac allograft in prolonging its survival time in mouse heart transplantation. Key words: Regulatory T cell; Costimulatory pathway; Dendritic cell; CD40; Heart transplantation

Induction of CD4+CD25+ T Cells and Control of Cardiac Allograft Rejection by CD40/CD40L Costimulatory Pathway Blockade in Mice

BackgroundRejection is a major problem in organ transplantation. We speculated that dendritic cells (DCs) with low expression of CD40 may inhibit T-cell responses providing protective effects on organ transplantions. MethodsRNA interference (RNAi) is an effective approach to degrade RNA levels of a target gene. We used RNAi to reduce CD40 levels in mouse bone marrow-derived DCs. Allogeneic T-lymphocyte proliferation stimulated by DCs was assessed in mixed lymphocyte reactions. A mouse model of heterotopic abdominal heart transplantation was performed to evaluate survival times and histologic grade of acute rejection at 7 days after transplantation. CD4+CD25+ regulatory T cells (Tregs) in peripheral blood were quantified by flow cytometry. ResultsMouse DCs with reduced CD40 expression lowered the proliferation of recipient T cells. More DCs with silenced CD40 delayed cardiac allograft rejection. ConclusionsReduction of CD40 in DCs induced peripheral Tregs and delayed cardiac allograft rejection.