The transcriptional regulator Aire coopts the repressive ATF7ip-MBD1 complex for the induction of immunotolerance

The maintenance of immune tolerance requires the deletion of self-reactive T cells in the thymus. The expression of tissue-specific antigen genes (TSAs) by thymic epithelial cells is critical for this process and depends on the activity of the Autoimmune Regulator (Aire) protein, however, the molecular mechanism(s) Aire uses to target TSA gene loci are unknown. Here we identified two Aire-interacting proteins – activating transcription factor 7 interacting protein (ATF7ip) and methyl CpG binding protein 1 (MBD1) –that are required for Aire’s targeting of TSA geneloci. Moreover, Mbd1−/− mice developed pathological autoimmunity and had a defect in Aire-dependent thymic TSA gene expression underscoring the critical importance of Aire’s interaction with the ATF7ip-MBD1 protein complex in maintaining central tolerance

Deep-phenotyping of Tregs identifies an immune signature for idiopathic aplastic anemia and predicts response to treatment

Idiopathic aplastic anemia (AA) is an immune-mediated and serious form of bone marrow failure. Akin to other autoimmune diseases, we have previously shown that in AA regulatory T-cells (Tregs) are reduced in number and function. The aim of this study was to further characterize Treg subpopulations in AA and investigate the potential correlation between specific Treg subsets and response to immunosuppressive therapy (IST) as well as their in-vitro expandability for potential clinical use. Using mass cytometry (CyTOF) and an unbiased multidimensional analytical approach, we identified two specific human Treg subpopulations (Treg A and Treg B) with distinct phenotypes, gene-expression, expandability and function. Treg subpopulation B, predominates in IST responder patients, has a memory/activated phenotype (with higher expression of CD95, CCR4 and CD45RO within FOXP3hi, CD127lo Tregs), expresses the IL- 2/STAT5 pathway and cell-cycle commitment genes. Furthermore, in-vitro expanded Tregs become functional and with the characteristics of Treg subpopulation B. Collectively, this study identifies human Treg subpopulations that can be used as predictive biomarkers for response to IST in AA and potentially other autoimmune diseases. We also show that Tregs from AA patients are IL-2 sensitive and expandable in-vitro, suggesting novel therapeutic approaches such as low dose IL-2 therapy and/or expanded autologous Tregs and meriting further exploration

Minimum Information about T Regulatory Cells: A Step toward Reproducibility and Standardization.

Cellular therapies with CD4+ T regulatory cells (Tregs) hold promise of efficacious treatment for the variety of autoimmune and allergic diseases as well as posttransplant complications. Nevertheless, current manufacturing of Tregs as a cellular medicinal product varies between different laboratories, which in turn hampers precise comparisons of the results between the studies performed. While the number of clinical trials testing Tregs is already substantial, it seems to be crucial to provide some standardized characteristics of Treg products in order to minimize the problem. We have previously developed reporting guidelines called minimum information about tolerogenic antigen-presenting cells, which allows the comparison between different preparations of tolerance-inducing antigen-presenting cells. Having this experience, here we describe another minimum information about Tregs (MITREG). It is important to note that MITREG does not dictate how investigators should generate or characterize Tregs, but it does require investigators to report their Treg data in a consistent and transparent manner. We hope this will, therefore, be a useful tool facilitating standardized reporting on the manufacturing of Tregs, either for research purposes or for clinical application. This way MITREG might also be an important step toward more standardized and reproducible testing of the Tregs preparations in clinical applications

Immune profiling of operational tolerance in liver transplantation

[cat] L'acceptació indefinida dels òrgans trasplantats mantenint el correcte funcionament de l'empelt sense necessitat d'administrar l'agressiu tractament immunosupressor constitueix el principal objectiu de la investigació clínica en el camp del trasplantament. Tot i que aquest fenomen s'observa amb freqüència en models animals, la tolerància immunològica a l'empelt en essers humans es redueix a un limitat grup de pacients, principalment en trasplantats hepàtics, considerats tolerants operacionals. L'objectiu de l'estudi és precisament la caracterització immunològica dels pacients operacionalment tolerants desprès del trasplantament de fetge. L'anàlisi descriptiu dels diferents paràmetres immunològics en sang perifèrica, mitjançant citometria de flux i expressió genètica, permetria delimitar la contribució de les principals subpoblacions immunològiques en l'acceptació de l'empelt hepàtic i els possibles mecanismes moleculars responsables del procés de tolerància. Els receptors hepàtics tolerants mostren un major numero de limfòcits reguladors CD4+CD25+CD62Lhigh Foxp3+ que els pacients no tolerants, però no que els controls sans, evidenciant la possible interacció dels fàrmacs immunosupressors en els limfòcits T reguladors. Així mateix, els pacients tolerants exhibeixen una proporció de limfòcits gammadelta superior, i una inversió en el quocient de les subpoblacions delta1+/delta2+ respecte als receptors dependents de immunosupressió i els controls, conseqüència de l'expansió del subtipus limfocitari Vdelta1. L'anàlisi de l'expressió genètica de sang perifèrica manifesta diferencies significatives en el patró d¡expressió dels pacients tolerants respecte als receptors no tolerants i controls sans. Aquests canvis transcripcionals varen ser validats amb mostres independents mitjançant PCR a temps real i a nivell proteic mitjançant citometria de flux. Els resultats revelen un increment en l'expressió de gens relacionats amb cèl·lules NK i limfòcits gammadelta, suggerint un paper central del sistema immune innat en el manteniment de l'estat de tolerància. L'estudi realitzat no solsament proporciona un major coneixement dels mecanismes relacionats en la tolerància hepàtica, també suggereix que l'ús de biomarcadors, com el patró d'expressió genètica en sang perifèrica, podria ser utilitzat com a test diagnòstic en la practica clínica per identificar receptors tolerants a qui es pot retirar la teràpia immunosupressora

Immunotolerance in Liver Transplantation

AbstractThe burden of life-long immunosuppressive medication must be overcome if progress is to be made in long-term outcomes following transplantation. The liver exhibits intrinsic tolerogenic properties that contribute to a unique propensity toward spontaneous acceptance when transplanted. Hence, a proportion of liver transplant recipients develop a state of immunotolerance and display persistently normal allograft function despite the discontinuation of immunosuppression. However, this phenomenon remains elusive for the majority of recipients. Investigations performed in experimental models of spontaneous liver allograft tolerance and in clinical cases of immunosuppression-free liver transplant acceptance have yielded mechanistic insights at the heart of recent strategies toward tolerance prediction and promotion. Results from recent clinical trials signal a shift in how liver allograft tolerance is viewed—not an elusive rarity of academic interest, but a potentially relevant clinical opportunity, which can be safely pursued if appropriately targeted.</jats:p

A yeast-based assay reveals a functional defect of the Q488H polymorphism in human Hsp90alpha

It has been argued that the molecular chaperone Hsp90 guards the organism against genetic variations by stabilizing variant Hsp90 substrate proteins. However, little is known about polymorphisms affecting its own functions. We have followed up on a recent study describing two polymorphisms that alter the amino acid sequences of the two Hsp90 isoforms Hsp90alpha and Hsp90beta. Hsp90 is essential for cell proliferation in the budding yeast Saccharomyces cerevisiae, but the human proteins can replace the endogenous ones. In this growth assay, the variant V656M of Hsp90beta was indistinguishable from wild-type. In contrast, the Hsp90alpha variant Q488H, which carries an alteration of a very highly conserved residue, was severely defective for growth compared to wild-type Hsp90alpha. Hence, the characteristics of this yeast-based system-simplicity, rapidity, low cost-make it ideal for phenotype screening of polymorphisms in HSP90 and possibly many other human genes

A yeast-based assay reveals a functional defect of the Q488H polymorphism in human Hsp90alpha

It has been argued that the molecular chaperone Hsp90 guards the organism against genetic variations by stabilizing variant Hsp90 substrate proteins. However, little is known about polymorphisms affecting its own functions. We have followed up on a recent study describing two polymorphisms that alter the amino acid sequences of the two Hsp90 isoforms Hsp90alpha and Hsp90beta. Hsp90 is essential for cell proliferation in the budding yeast Saccharomyces cerevisiae, but the human proteins can replace the endogenous ones. In this growth assay, the variant V656M of Hsp90beta was indistinguishable from wild-type. In contrast, the Hsp90alpha variant Q488H, which carries an alteration of a very highly conserved residue, was severely defective for growth compared to wild-type Hsp90alpha. Hence, the characteristics of this yeast-based system-simplicity, rapidity, low cost-make it ideal for phenotype screening of polymorphisms in HSP90 and possibly many other human genes

Immunological Predictors of Nonresponse to Directly Acting Antiviral Therapy in Patients With Chronic Hepatitis C and Decompensated Cirrhosis

Abstract Background Sustained virological response rates (SVRs) to directly acting antiviral (DAA) therapy for hepatitis C virus (HCV) are lower in decompensated cirrhosis. Markers of innate immunity predict nonresponse to interferon-based HCV treatment; however, whether they are associated with the response to DAAs in patients with decompensation is not known. Methods Information on demographics, adherence, viral kinetics, and resistance were gathered prospectively from a cohort with decompensated cirrhosis treated with 12 weeks of DAAs. C-X-C motif chemokine-10 (CXCL-10) level and T-cell and natural killer (NK) cell phenotype were analyzed pretreatment and at 4 and 12 weeks of treatment. Results Of 32 patients, 24 of 32 (75%) achieved SVR (responders). Eight of 32 (25%) experienced relapse after the end of treatment (nonresponders). There were no differences in demographics or adherence between groups. Nonresponders had higher CXCL-10; 320 pg/mL (179461) vs 109 pg/mL (88170) in responders (P &amp;lt; .001) and differential CXCL-10 dynamics. Nonresponders had lower NK cell frequency, higher expression of activation receptor NKp30, and lower frequency of the NK subset CD56−CD16+. Conclusions Nonresponders to DAAs displayed a different NK phenotype and CXCL-10 profile to responders. Nonresponders did not have poorer adherence or baseline virological resistance, and this shows that immunological parameters are associated with treatment response to interferon-free treatment for HCV in individuals with decompensated cirrhosis. </jats:sec