Connection of BANK1, Tolerance, Regulatory B cells, and Apoptosis: Perspectives of a Reductionist Investigation

International audienceBANK1 transcript is upregulated in whole blood after kidney transplantation in tolerant patients. In comparison to patients with rejection, tolerant patients display higher level of regulatory B cells (Bregs) expressing granzyme B (GZMB ) that have the capability to prevent effector T cells proliferation. However, BANK1 was found to be decreased in these GZMB Bregs. In this article, we investigated seven different transcriptomic studies and mined the literature in order to make link between BANK1, tolerance and Bregs. As for GZMB Bregs, we found that BANK1 was decreased in other subtypes of Bregs, including IL10 and CD24 CD38 transitional regulatory B cells, along with BANK1 was down-regulated in activated/differentiated B cells, as in CD40-activated B cells, in leukemia and plasma cells. Following a reductionist approach, biological concepts were extracted from BANK1 literature and allowed us to infer association between BANK1 and immune signaling pathways, as STAT1, Fc??RIIB, TNFAIP3, TRAF6, and TLR7. Based on B cell signaling literature and expression data, we proposed a role of BANK1 in B cells of tolerant patients that involved BCR, IP3R, and PLCG2, and a link with the apoptosis pathways. We confronted these data with our experiments on apoptosis in total B cells and Bregs, and this suggests different involvement for BANK1 in these two cells. Finally, we put in perspective our own data with other published data to hypothesize two different roles for BANK1 in B cells and in Bregs

Potential role of soluble ST2 protein in idiopathic nephrotic syndrome recurrence following kidney transplantation.

International audienceBACKGROUND: Corticosteroid-resistant idiopathic nephrotic syndrome (INS) recurs rapidly after transplantation in 30% to 50% of transplant recipients, suggesting the presence of 1 or more circulating factors that alter the glomerular filtration barrier. We investigated the possible role in INS recurrence of soluble ST2 (sST2) protein, a marker of T helper type 2 (T(H)2) cells and a factor predicted to be regulated by the transcription factor c-Maf; involvement of sST2 protein would be consistent with the observation that both T(H)2 cells and c-Maf appear to be activated during INS relapse. STUDY DESIGN: Retrospective observational study. SETTING & PARTICIPANTS: Patients with biopsy-proven corticosteroid-resistant INS who had undergone kidney transplantation between September 1983 and April 2007 (n = 71). A control group consisting of proteinuric transplant recipients with kidney failure unrelated to INS (n = 34). PREDICTOR: Patients who developed INS recurrence after transplantation (n = 31) were compared with those in whom INS did not recur (n = 40) and the control group. Recurrence of INS was defined as urine protein excretion greater than 2 g/d immediately after transplantation that persisted at greater than 1 g/d despite treatment or a kidney graft biopsy showing minimal change glomerulonephritis or focal segmental glomerulosclerosis. OUTCOMES & MEASUREMENTS: Urine protein excretion in the 3 groups was 5.0 g/d (range, 1.3 to 10.5), 0.14 g/d (range, 0 to 0.46), and 4.3 g/d (range, 3 to 6.2). The sST2 protein was analyzed both quantitatively and qualitatively in patient sera, and its activity was tested in vitro on a mouse podocyte cell line and in vivo in rats. RESULTS: sST2 protein levels were significantly increased after transplantation in patients with INS recurrence compared with the 2 other groups (617.5 versus 23 pg/mL; P < 0.001 and 158.5 pg/mL; P < 0.01 respectively). However, patients with recurrence expressed a normal sST2 isoform, and the sST2 protein was unable to induce podocyte injury in vitro or trigger proteinuria in rats. LIMITATIONS: Pretransplantation and posttransplantation sera do not always represent paired samples. CONCLUSIONS: These data suggest that sST2 protein is a marker of INS recurrence that does not seem to be involved in the development of INS

Increased IGM and IGG anti-NEU5GC antibodies in infectious mononucleosis (IMN): link with multiple sclerosis (MS)?

International audienceIntroduction: Multiple Sclerosis (MS) is a chronic inflammatory and demyelinating disease which displays an autoimmune component at its overt clinical stage. Among etiological hypotheses, the potential initiating role of EBV in the disease has been raised following works linking EBNA levels and the risk of MS occurrence [1] showing a linkage between the occurrence of IMN and MS. Our hypothesis is that a vigorous production of anti-Neu5Gc in IMN (as indirectly measured by Paul-Bunnell Davidson reaction) may induce brain blood barrier alterations when the EBV primo-infection is contemporary of an extraordinary high frequency of EBV committed T cells and of circulating EBV+ memory B cells[2]. Our aim was to measure anti-Neu5Gc IgG and IgM levels during the IMN and to investigate whether levels of anti-NeuGc could be also increased in MS. Material and Methods: Sera from 49 patients with overt IMN were collected from the University Hospital of Grenoble and Nantes. The gender ratio was 22F/ 27M. The age average was 24 years (range: 7- 65). Two cohorts of EBV negative individuals (n= 45) and healthy individuals (n= 120) were used as controls. A second cohort of 46 patients with proven MS was collected from the University Hospital of Nantes. The gender ratio was 30F/ 16M. The age average was 48 years (range: 22-73). This cohort contained 30 patients presenting a Remitting Relapsing (RR) form (65.2%) and 16 with a Secondary or Primary Progressive (SP-PP) one (34.7%). A cohort of healthy individuals (n= 37) matched for gender and age was used as controls. On these samples, we performed two Elisa [3][4] to quantify anti-Neu5Gc IgG and IgM antibodies. Results: We showed a highly significant increase in anti-Neu5Gc IgM in IMN patients in comparison to EBV negative controls (0.82±0.16 vs. 0.15±0.05 ng/ul; p<0.0001). Anti-Neu5Gc IgG were also, though less dramatically, increased (3.64±0.6 vs. 2.78±0.57ng/ul; p=0.04). The values obtained in IMN differed significantly to healthy individuals (0.82±0.16 vs. 0.2±0.03 ng/ul;p<0.0001 for IgM and 3.63±0.6 vs. 2.74±0.3 ng/ul; p= 0.01 for IgG). The levels of anti-α1-3Gal epitopes, an other type of «xeno» antibody against a sugar not synthesized by normal individuals were also increased during IMN (12.4±1.1 vs. 9.67±1.46 ng/ul for EBV negative controls and vs. 11.7±3.4 ng/ul for healthy individuals; p<0.0001 for both). We found neither increase in anti-Neu5gc antibodies in this small MS patient cohort (p=0.8 for IgM and p=0.84 for IgG), nor in RR or SP-PP subgroups. We found no correlation between the anti-Neu5Gc titers and age or gender of IMN or MS patients, or of healthy individuals. Conclusion: Despite the fact that EVB does not express Neu5Gc, anti-Neu5Gc antibodies are strongly increased in IMN patients, suggesting that uptake of Neu5Gc from dietary sources by EBV infected cells induces them to become more immunogenic during the acute disease. However our data did not evidence higher anti-Neu5Gc antibodies in established MS

Extrarenal effects on the pathogenesis and relapse of idiopathic nephrotic syndrome in Buffalo/Mna rats

Buffalo/Mna rats spontaneously develop a focal segmental glomerulosclerosis with a histological pattern similar to the human disease. In this study, we investigated the potential of recurrence of the disease by transplantation of normal kidneys into Buffalo/Mna recipients. Kidneys from healthy LEW.1W rats were grafted into proteinuric 6-month-old Buffalo/Mna rats without or with specific tolerance induction following donor-specific transfusion (DST) aimed at controlling host anti-donor immune responses. The inverse combination was carried out to determine whether a proteinuric Buffalo/Mna kidney can recover its permselectivity in a normal environment. As a control, LEW.1W kidneys were grafted into Wistar Furth recipients. After transplantation without DST, recurrence of proteinuria in LEW.1W kidneys appeared at approximately 10 days, possibly associated with rejection of the graft. In the same combination with DST, proteinuria occurred after 20 days, and the attendant glomerular damage suggested that the initial kidney disease had recurred. Transplanted control animals remained free of proteinuria. In the opposite combination, the proteinuria and the lesions of Buffalo/Mna kidneys regressed after transplantation into healthy LEW.1W rats. The recurrence of proteinuria after transplantation in Buffalo/Mna and the remission of lesions in Buffalo/Mna kidneys transplanted into normal hosts suggests that Buffalo/Mna rats express circulating albuminuric factors, which may be relevant to the relapse of idiopathic nephrotic syndrome in humans

Induction of T Regulatory Cells Attenuates Idiopathic Nephrotic Syndrome

Buffalo/Mna rats spontaneously develop FSGS and nephrotic syndrome as a result of an immune disorder. Similar to some humans with FSGS, the disease recurs after renal transplantation, suggesting the involvement of a circulating factor. Here, we tested the effect of several immunosuppressive treatments on these rats. Although corticosteroids, cyclosporin A, and anti–T cell receptor treatment reduced proteinuria, only the deoxyspergualin derivative LF15-0195 led to a rapid and complete normalization of proteinuria. Furthermore, this compound led to the regression of renal lesions during both the initial disease and posttransplantation recurrence. The frequency of splenic and peripheral CD4+CD25+FoxP3+ T lymphocytes significantly increased with remission. Moreover, the transfer of purified LF15-0195–induced CD4+CD25+ T cells to irradiated Buff/Mna rats significantly reduced their proteinuria compared with the transfer of untreated control cells, suggesting that LF15-0195 induces regulatory T cells that are able to induce regression of rat nephropathy. These data suggest that idiopathic nephrotic syndrome/FSGS disease can be regulated by cellular transfer, but how this regulation leads to the reorganization of the podocyte cytoskeleton remains to be determined

Anti-Gal and Anti-Neu5Gc Responses in Nonimmunosuppressed Patients After Treatment With Rabbit Antithymocyte Polyclonal IgGs

International audienceBackground. Polyclonal antihuman thymocyte rabbit IgGs (antithymocyte globulin [ATG]) are popular immunosuppressive drugs used to prevent or treat organ or bone-marrow allograft rejection, graft versus host disease, and autoimmune diseases. However, animal-derived glycoproteins are also strongly immunogenic and rabbit ATG induces serum sickness disease in almost all patients without additional immunosuppressive drugs, as seen in the Study of Thymoglobulin to arrest Type 1 Diabetes (START) trial of ATG therapy in new-onset type 1 diabetes.Methods. Using enzyme-linked immunosorbent assay, we analyzed serial sera from the START study to decipher the various anti-ATG specificities developed by the patients in this study: antitotal ATG, but also antigalactose-α1-3-galactose (Gal) and anti-Neu5Gc antibodies, 2 xenocarbohydrate epitopes present on rabbit IgG gly-cans and lacking in humans.Results. We show that diabetic patients have substantial levels of preexisting antibodies of the 3 specificities, before infusion, but of similar levels as healthy individuals. ATG treatment resulted in highly significant increases of both IgM (for anti-ATG and anti-Neu5Gc) and IgG (for anti-ATG,-Gal, and-Neu5Gc), peaking at 1 month and still detectable 1 year postinfusion. Conclusions. Treatment with rabbit polyclonal IgGs in the absence of additional immunosuppression results in a vigorous response against Gal and Neu5Gc epitopes, contributing to an inflammatory environment that may compromise the efficacy of ATG therapy. The results also suggest using IgGs lacking these major xenoantigens may improve safety and efficacy of ATG treatment

Glycan microarray reveal induced IgGs repertoire shift against a dietary carbohydrate in response to rabbit anti-human thymocyte therapy.

Humans have circulating antibodies against diverse glycans containing N-glycolylneuraminic acid (Neu5Gc) due to function-loss mutation of the CMAH gene. This xenogenic non-human carbohydrate is abundant in red meat, xenografts and biotherapeutics. Low levels of diet-derived Neu5Gc is also present on normal human endothelial cells, and together with anti-Neu5Gc antibodies could potentially mediate "xenosialitis" chronic-inflammation. Rabbit anti-human thymocyte globulin (ATG) is a drug containing polyclonal IgG glycoproteins commonly used as an immunosuppressant in human transplantation and autoimmune diseases. In type-1 diabetes patients, infusion of Neu5Gc-glycosylated ATG caused increased global anti-Neu5Gc response. Here, for the first time we explore changes in anti-Neu5Gc IgG repertoire following the immunization elicited by ATG, compared with the basal antibodies repertoire that reflect exposure to dietary-Neu5Gc. We used glycan microarrays with multiple Neu5Gc-glycans and controls to elucidate eventual differences in ATG-elicited repertoire, before/after ATG administration and track their kinetics (0, 1, 18 and 24 months). Response of all basal-pre-existing Neu5Gc-specific antibodies rapidly increased. This response peaked at one month post-ATG, with enhanced affinity, then resolved at 18-24 months. Induced-antibodies showed expanded diversity and de-novo recognition of different Neu5Gc-glycans, including endogenous glycolipids, that was further validated by affinity-purified anti-Neu5Gc antibodies from patients' sera. These findings strongly suggest that ATG-induced anti-Neu5Gc IgGs represent a secondary exposure to this dietary carbohydrate-antigen in humans, with immune memory. Given their modified recognition patterns, ATG-evoked anti-Neu5Gc antibodies could potentially mediate biological effects different from pre-existing antibodies

Glycan microarray reveal induced IgGs repertoire shift against a dietary carbohydrate in response to rabbit anti-human thymocyte therapy.

International audienceHumans have circulating antibodies against diverse glycans containing N-glycolylneuraminic acid (Neu5Gc) due to function-loss mutation of the CMAH gene. This xenogenic non-human carbohydrate is abundant in red meat, xenografts and biotherapeutics. Low levels of diet-derived Neu5Gc is also present on normal human endothelial cells, and together with anti-Neu5Gc antibodies could potentially mediate "xenosialitis" chronic-inflammation. Rabbit anti-human thymocyte globulin (ATG) is a drug containing polyclonal IgG glycoproteins commonly used as an immunosuppressant in human transplantation and autoimmune diseases. In type-1 diabetes patients, infusion of Neu5Gc-glycosylated ATG caused increased global anti-Neu5Gc response. Here, for the first time we explore changes in anti-Neu5Gc IgG repertoire following the immunization elicited by ATG, compared with the basal antibodies repertoire that reflect exposure to dietary-Neu5Gc. We used glycan microarrays with multiple Neu5Gc-glycans and controls to elucidate eventual differences in ATG-elicited repertoire, before/after ATG administration and track their kinetics (0, 1, 18 and 24 months). Response of all basal-pre-existing Neu5Gc-specific antibodies rapidly increased. This response peaked at one month post-ATG, with enhanced affinity, then resolved at 18-24 months. Induced-antibodies showed expanded diversity and de-novo recognition of different Neu5Gc-glycans, including endogenous glycolipids, that was further validated by affinity-purified anti-Neu5Gc antibodies from patients' sera. These findings strongly suggest that ATG-induced anti-Neu5Gc IgGs represent a secondary exposure to this dietary carbohydrate-antigen in humans, with immune memory. Given their modified recognition patterns, ATG-evoked anti-Neu5Gc antibodies could potentially mediate biological effects different from pre-existing antibodies