Differential IL-21 signaling in APCs leads to disparate Th17 differentiation in diabetes-susceptible NOD and diabetes-resistant NOD.Idd3 mice.

Type 1 diabetes (T1D) is an autoimmune disease that shows familial aggregation in humans and likely has genetic determinants. Disease linkage studies have revealed many susceptibility loci for T1D in mice and humans. The mouse T1D susceptibility locus insulin-dependent diabetes susceptibility 3 (Idd3), which has a homologous genetic interval in humans, encodes cytokine genes Il2 and Il21 and regulates diabetes and other autoimmune diseases; however, the cellular and molecular mechanisms of this regulation are still being elucidated. Here we show that T cells from NOD mice produce more Il21 and less Il2 and exhibit enhanced Th17 cell generation compared with T cells from NOD.Idd3 congenic mice, which carry the protective Idd3 allele from a diabetes-resistant mouse strain. Further, APCs from NOD and NOD.Idd3 mice played a central role in this differential Th17 cell development, and IL-21 signaling in APCs was pivotal to this process. Specifically, NOD-derived APCs showed increased production of pro-Th17 mediators and dysregulation of the retinoic acid (RA) signaling pathway compared with APCs from NOD.Idd3 and NOD.Il21r-deficient mice. These data suggest that the protective effect of the Idd3 locus is due, in part, to differential RA signaling in APCs and that IL-21 likely plays a role in this process. Thus, we believe APCs provide a new candidate for therapeutic intervention in autoimmune diseases

Analysis of IL2/IL21 Gene Variants in Cholestatic Liver Diseases Reveals an Association with Primary Sclerosing Cholangitis

Background/Aims: The chromosome 4q27 region harboring IL2 and IL21 is an established risk locus for ulcerative colitis (UC) and various other autoimmune diseases. Considering the strong coincidence of primary sclerosing cholangitis (PSC) with UC and the increased frequency of other autoimmune disorders in patients with primary biliary cirrhosis (PBC), we investigated whether genetic variation in the IL2/IL21 region may also modulate the susceptibility to these two rare cholestatic liver diseases. Methods: Four strongly UC-associated single nucleotide polymorphisms (SNPs) within the KIAA1109/TENR/IL2/IL21 linkage disequilibrium block were genotyped in 124 PBC and 41 PSC patients. Control allele frequencies from 1,487 healthy, unrelated Caucasians were available from a previous UC association study. Results: The minor alleles of all four markers were associated with a decreased susceptibility to PSC (rs13151961: p = 0.013, odds ratio (OR) 0.34; rs13119723: p = 0.023, OR 0.40; rs6822844: p = 0.031, OR 0.41; rs6840978: p = 0.043, OR 0.46). Moreover, a haplotype consisting of the four minor alleles also had a protective effect on PSC susceptibility (p = 0.0084, OR 0.28). A haplotype of the four major alleles was independently associated with PSC when excluding the patients with concomitant inflammatory bowel disease (p = 0.033, OR 4.18). Conclusion: The IL2/IL21 region may be one of the highly suggestive but so far rarely identified shared susceptibility loci for PSC and UC. Copyright (C) 2011 S. Karger AG, Base

Inflammation-Driven Reprogramming of CD4+Foxp3+ Regulatory T Cells into Pathogenic Th1/Th17 T Effectors Is Abrogated by mTOR Inhibition in vivo

While natural CD4+Foxp3+ regulatory T (nTREG) cells have long been viewed as a stable and distinct lineage that is committed to suppressive functions in vivo, recent evidence supporting this notion remains highly controversial. We sought to determine whether Foxp3 expression and the nTREG cell phenotype are stable in vivo and modulated by the inflammatory microenvironment. Here, we show that Foxp3+ nTREG cells from thymic or peripheral lymphoid organs reveal extensive functional plasticity in vivo. We show that nTREG cells readily lose Foxp3 expression, destabilizing their phenotype, in turn, enabling them to reprogram into Th1 and Th17 effector cells. nTREG cell reprogramming is a characteristic of the entire Foxp3+ nTREG population and the stable Foxp3NEG TREG cell phenotype is associated with a methylated foxp3 promoter. The extent of nTREG cell reprogramming is modulated by the presence of effector T cell-mediated signals, and occurs independently of variation in IL-2 production in vivo. Moreover, the gut microenvironment or parasitic infection favours the reprogramming of Foxp3+ TREG cells into effector T cells and promotes host immunity. IL-17 is predominantly produced by reprogrammed Foxp3+ nTREG cells, and precedes Foxp3 down-regulation, a process accentuated in mesenteric sites. Lastly, mTOR inhibition with the immunosuppressive drug, rapamycin, stabilizes Foxp3 expression in TREG cells and strongly inhibits IL-17 but not RORγt expression in reprogrammed Foxp3− TREG cells. Overall, inflammatory signals modulate mTOR signalling and influence the stability of the Foxp3+ nTREG cell phenotype

Role of vacuolar protein sorting pathway factor CHMP4B in HIV-1 budding

A Dominant Negative (DN) fusion derivative of CHMP4B was generated, EGFP-CHMP4B, in order to disrupt the function of endogenous CHMP4B and thus to elucidate the potential role of this VPS factor in HIV-1 budding. Indeed, the over-expression of this fusion protein led to reductions in viral production.In order to validate these findings, RNAi (RNA interference) technology was harnessed. Small interfering RNA (siRNA) was designed to deplete endogenous CHMP4B. The results show that depletion of CHMP4B via siRNA ablates HIV-1 production.The disruption of the VPS pathway can be determined by monitoring the fate of TfR (Transferrin Receptor), a cell-surface receptor that is recycled via the VPS pathway. The uptake of Tf can also be monitored to determine whether the VPS pathway is functional. Over-expression of the fusion derivative of CHMP4B or treatment of the cells with CHMP4B-specific siRNA leads to the disruption of the VPS pathway, as determined by confocal microscopy.Interestingly, down-regulation of CHMP4B expression also severely restricted the release of EIAV (Equine Infectious Anemia Virus), which harbors an YPDL motif within the p9 region of its Gag

Analyzing the Validity of Physical Activity Trackers In Terms of Heart Rate and Energy Expenditure

The purpose of this study was to evaluate the agreement between two popular commercially available activity trackers and a metabolic cart in terms of energy expenditure and heart rate. The activity trackers analyzed were the Apple Watch Series 3 and the Fitbit Versa. The research hypothesis stated that a difference would be found between the Apple Watch Series 3, the Fitbit Versa, and the Parvo Medics 2400 metabolic analyzer in terms of energy expenditure and heart rate.Participants (N = 5; average age: 23.6 1.7 years) completed a Bruce Protocol maximal test. Participants were connected to the ParvoMedic metabolic analyzer while wearing the Apple Watch on their left wrist and the Fitbit Versa on their right wrist. Heart rate and caloric expenditure values were obtained from each device for analysis. Two matched-pairs t-tests were performed to compare the Apple Watch and Fitbit to the metabolic cart. The Fitbit significantly underreported heart rate and energy expenditure when compared to the true value given by the metabolic cart (p = 0.003). The Apple Watch Series 3 did appear to report slightly lower than the metabolic cart, however, the value was not statistically significant (p = 0.0981). Therefore, the research hypotheses is accepted for the Fitbit, but rejected for the Apple Watch activity tracker. Future studies should aim to gather a larger sample size

Functional dynamics of CD4+Foxp3+ regulatory T cells throughout the progression of type 1 diabetes: lessons learned from the NOD mouse model

Type 1 diabetes (T1D) results from the T cell-mediated destruction of the insulin-producing -islets. CD4+CD25+Foxp3+ regulatory T (Treg) cells have emerged as a central control point in T1D progression. A correlation exists between T1D and T cell hyporesponsiveness at the time of insulitis, which results in a decline in IL-2. A growing body of evidence strongly demonstrates that IL-2 is an important signal for Treg cell competitive fitness. Congenic non-obese diabetic (NOD) mice introgressed with the Idd3B6 genetic interval from non-autoimmune prone strain (C57/BL6) (Idd3B6) exhibit a marked delay in disease incidence, onset and severity relative to wild-type (WT) NOD mice. The candidate gene within the Idd3B6 locus is Il2. Considering the critical role of IL-2 in Treg cell functions, we hypothesized that the Idd3B6 locus confers T1D protection by promoting the survival, function or recruitment of Treg cells. We show that NOD mice succumb to T1D due to a marked age-related decline in the compartment of cycling Treg cells due to IL-2 deficiency, a defect corrected by IL-2 therapy or the Idd3B6 locus. Interestingly, inducible costimulator (ICOS), which is IL-2-dependent, is predominantly expressed by intra-islet resident Treg cells, favors their suppressive functions and maintains production of IL-10, as demonstrated by blockade and genetic ablation studies. Thus, ICOS imprints Treg cells with their suppressive signature phenotype. In contrast to T1D-protected animals, the expression of ICOS in the cycling Treg cell compartment also diminishes with age in WT NOD mice, suggesting that loss of ICOS signals correlates with waning of Treg cell functional potency. ICOS-ligand (ICOS-L) is expressed exclusively within the target organ by dendritic cells (DC) and its expression also declines over time, suggesting bidirectional ICOS/ICOS-L signalling and conditioning between Treg cells and DC. Furthermore, DC from pancreatic sites of NOD mice exhibit differential costimuLe maintien de la tolérance au soi implique des mécanismes centraux et périphériques assurés, notamment, par les cellules régulatrices T (Treg), caractérisées par l'expression de CD25 et Foxp3. Des modifications numériques et/ou fonctionnelles de ces populations cellulaires pourraient être la cause de la rupture de tolérance au soi. Nous avons entrepris l'analyse numérique et surtout fonctionnelle de ces cellules Treg au cours du diabète de type 1 dans le modèle murin "non-obese diabetic" (NOD). Le diabète de type 1 est une maladie autoimmune aboutissant à une destruction totale des cellules bêta des îlots de Langerhans par les cellules T CD4 autoréactives. La prédisposition génétique et les facteurs de risque déclenchent le diabète insulino-dépendant. Les cellules Treg constituent le mécanisme prédominant de suppression contre les cellules T pathogènes. Les résultats tendent à montrer que les cellules Treg déploient leurs fonctions régulatrices, mais qu'elles déclinent avec l'âge. Le nombre de cellules Treg ainsi que leurs fonctions d'inhibition de la prolifération et sécrétion de cytokines inflammatoires des cellules T CD4 effectrices sont altérées chez la souris NOD. Par ailleurs, les défaults numérique et fonctionnel des cellules Treg que semblent présenter ces souris sont restitués pas des variantes alléliques d'IL-2, un facteur essentiel à l'homéostase des cellules Treg, chez la souris congénique résistante au diabète NOD.B6 Idd3. En aval de la signalisation d'IL-2, les résultats dépeignent un rôle préponderant pour la stimulation ICOS dans l'activation des fonctions régulatrices des Treg. De plus, ICOS promeut l'expression de la cytokine immunomodulatrice IL-10, impliqué dans l'amortissement du diabète. La baisse d'ICOS par les cellules Treg coincide avec le diabète, démontrant une relation étroite entre la costimulation ICOS et l'autoimmunité. La stimulation fournie par les cellules dendritiques