Josselyn E. Garcia-Perez

Familial autoinflammation with neutrophilic dermatosis reveals a regulatory mechanism of pyrin activation

A mutation in pyrin that disrupts regulation leads to autoinflammatory disease. Guarding inflammation The innate immune system is hard-wired to protect people from infection. However, mutations in these protective genes can lead to uncontrolled inflammation, resulting in autoinflammatory disease. Now, Masters et al. describe a family with an autoinflammatory disease caused by a previously unreported mutation in pyrin. This mutation disrupts pyrin regulation and mimics the effect of pathogen sensing by pyrin, leading to proinflammatory interleukin-1β (IL-1β) production. Indeed, targeting IL-1β resolved disease in one patient. These data suggest that pyrin is regulated through a guard-like mechanism, which guards against autoinflammation in humans. Pyrin responds to pathogen signals and loss of cellular homeostasis by forming an inflammasome complex that drives the cleavage and secretion of interleukin-1β (IL-1β). Mutations in the B30.2/SPRY domain cause pathogen-independent activation of pyrin and are responsible for the autoinflammatory disease familial Mediterranean fever (FMF). We studied a family with a dominantly inherited autoinflammatory disease, distinct from FMF, characterized by childhood-onset recurrent episodes of neutrophilic dermatosis, fever, elevated acute-phase reactants, arthralgia, and myalgia/myositis. The disease was caused by a mutation in MEFV, the gene encoding pyrin (S242R). The mutation results in the loss of a 14-3-3 binding motif at phosphorylated S242, which was not perturbed by FMF mutations in the B30.2/SPRY domain. However, loss of both S242 phosphorylation and 14-3-3 binding was observed for bacterial effectors that activate the pyrin inflammasome, such as Clostridium difficile toxin B (TcdB). The S242R mutation thus recapitulated the effect of pathogen sensing, triggering inflammasome activation and IL-1β production. Successful therapy targeting IL-1β has been initiated in one patient, resolving pyrin-associated autoinflammation with neutrophilic dermatosis. This disease provides evidence that a guard-like mechanism of pyrin regulation, originally identified for Nod-like receptors in plant innate immunity, also exists in humans.

Genetic predisposition for beta cell fragility underlies type 1 and type 2 diabetes

Type 1 (T1D) and type 2 (T2D) diabetes share pathophysiological characteristics, yet mechanistic links have remained elusive. T1D results from autoimmune destruction of pancreatic beta cells, whereas beta cell failure in T2D is delayed and progressive. Here we find a new genetic component of diabetes susceptibility in T1D non-obese diabetic (NOD) mice, identifying immune-independent beta cell fragility. Genetic variation in Xrcc4 and Glis3 alters the response of NOD beta cells to unfolded protein stress, enhancing the apoptotic and senescent fates. The same transcriptional relationships were observed in human islets, demonstrating the role of beta cell fragility in genetic predisposition to diabetes.

The microRNA-29 Family Dictates the Balance Between Homeostatic and Pathological Glucose Handling in Diabetes and Obesity

The microRNA-29 (miR-29) family is among the most abundantly expressed microRNA in the pancreas and liver. Here, we investigated the function of miR-29 in glucose regulation using miR-29a/b-1 (miR-29a)-deficient mice and newly generated miR-29b-2/c (miR-29c)-deficient mice. We observed multiple independent functions of the miR-29 family, which can be segregated into a hierarchical physiologic regulation of glucose handling. miR-29a, and not miR-29c, was observed to be a positive regulator of insulin secretion in vivo, with dysregulation of the exocytotic machinery sensitizing β-cells to overt diabetes after unfolded protein stress. By contrast, in the liver both miR-29a and miR-29c were important negative regulators of insulin signaling via phosphatidylinositol 3-kinase regulation. Global or hepatic insufficiency of miR-29 potently inhibited obesity and prevented the onset of diet-induced insulin resistance. These results demonstrate strong regulatory functions for the miR-29 family in obesity and diabetes, culminating in a hierarchical and dose-dependent effect on premature lethality.

Psychological comorbidity increases the risk for postinfectious IBS partly by enhanced susceptibility to develop infectious gastroenteritis

Objective Psychological factors increase the risk to develop postinfectious IBS (PI-IBS), but the mechanisms involved are unclear. As stress affects the immune system, we investigated the potential interaction between psychological factors, the immune response against infectious gastroenteritis (IGE) and the development of IGE and PI-IBS in a large cohort exposed to contaminated drinking water. Design 18 620 people exposed to contaminated drinking water (norovirus, Giardia lamblia, Campylobacter jejuni) were invited to participate in a prospective controlled cohort study. They were asked to complete questionnaires assessing demographic, psychological and clinical data during the outbreak and 1 year later. At both time points, in-depth immune function (peripheral blood and rectal biopsies) was studied in a subgroup of subjects. Results 1379 subjects completed the questionnaires during the outbreak, of which 271 developed IGE. Risk factors for IGE included younger age, pre-existing dyspepsia-like symptoms, anxiety and drinking contaminated tap water. Anxiety scores before the outbreak inversely correlated with interleukin-2-expressing CD4+ T cells (r=0.6, p=0.01, n=23). At follow-up, 34 of 172 (20%) IGE subjects developed IBS compared with 24/366 exposed participants (7%, p<0.0001, χ2 test). A Th2 cytokine phenotype at time of infection was associated with increased risk for PI-IBS 1 year later. Except for increased B cell numbers, no evidence for systemic or rectal mucosal immune activation in PI-IBS was demonstrated at follow-up. Conclusions Our study shows that the increased risk of patients with psychological comorbidity to develop PI-IBS may partly result from an increased susceptibility to develop IGE, possibly resulting from a Th2-immune bias. Trial registration number (ClinicalTrials.gov NCT01497847).

Inflammatory gene expression profile and defective IFN‐γ and granzyme K in natural killer cells of systemic juvenile idiopathic arthritis patients

Systemic juvenile idiopathic arthritis (JIA) is an immunoinflammatory disease characterized by arthritis and systemic manifestations. The role of natural killer (NK) cells in the pathogenesis of systemic JIA remains unclear. The purpose of this study was to perform a comprehensive analysis of NK cell phenotype and functionality in patients with systemic JIA.

Immunologic profiles of multiple sclerosis treatments reveal shared early B cell alterations

Objective: We undertook a systems immunology approach of the adaptive immune system in multiple sclerosis (MS), overcoming tradeoffs between scale and level of detail, in order to identify the immunologic signature of MS and the changes wrought by current immunomodulatory treatments. Methods: We developed a comprehensive flow cytometry platform measuring 38 immunologic cell types in the peripheral blood of 245 individuals in a routine clinical setting. These include patients with MS, untreated or receiving any of 4 current immunomodulatory treatments (interferon-β, glatiramer acetate, natalizumab, or fingolimod), patients with autoimmune thyroid disease, and healthy controls. Results: An increase in memory CD8+ T cells and B cells was observed in untreated patients with MS. Interferon-β and fingolimod induce significant changes upon multiple aspects of the peripheral immune system, with an unexpectedly prominent alteration of B cells. Overall, both treatments push the immune system in different directions, with only 2 significant effects shared across these treatments—an increase in transitional B cells and a decrease in class-switched B cells. We further identified heightened B cell-activating factor (BAFF) levels as regulating this shared B cell pathway. Conclusions: A systems immunology approach established different immunologic profiles induced by current immunomodulatory MS treatments, offering perspectives for personalized medicine. Pathways shared between the immunologic architecture of existing efficacious treatments identify targets for future treatment design.

Multiple sclerosis risk variants alter expression of co-stimulatory genes in B cells.

Increasing evidence implicates B cells in the pathogenesis of multiple sclerosis. Smets et al. report that the CD40 multiple sclerosis risk allele lowers CD40 expression, whereas the CD86 risk allele increases CD86 expression. B cells may have an important antigen presentation and immunoregulatory role in multiple sclerosis.

miR-29a-deficiency does not modify the course of murine pancreatic acinar carcinoma

The development of cancers involves the complex dysregulation of multiple cellular processes. With key functions in simultaneous regulation of multiple pathways, microRNA (miR) are thought to have important roles in the oncogenic formation process. miR-29a is among the most abundantly expressed miR in the pancreas. Together with altered expression in pancreatic cancer cell lines and biopsies, and known oncogenic functions in leukemia, this expression data has identified miR-29a as a key candidate for miR involvement in pancreatic cancer biology. Here we used miR-29a-deficient mice and the TAg model of pancreatic acinar carcinoma to functionally test the role of miR-29a in vivo. We found no impact of miR-29a loss on the development or growth of pancreatic tumours, nor on the survival of tumour-bearing mice. These results suggest that, despite differential expression, miR-29a is oncogenically neutral in the pancreatic acinar carcinoma context. If these results are extended to other models of pancreatic cancer, they would reduce the attractiveness of miR-29a as a potential therapeutic target in pancreatic cancer.

Abnormal differentiation of B cells and megakaryocytes in patients with Roifman syndrome

Background: Roifman syndrome is a rare inherited disorder characterized by spondyloepiphyseal dysplasia, growth retardation, cognitive delay, hypogammaglobulinemia, and, in some patients, thrombocytopenia. Compound heterozygous variants in the small nuclear RNA gene RNU4ATAC, which is necessary for U12‐type intron splicing, were identified recently as driving Roifman syndrome. Objective: We studied 3 patients from 2 unrelated kindreds harboring compound heterozygous or homozygous stem II variants in RNU4ATAC to gain insight into the mechanisms behind this disorder. Methods: We systematically profiled the immunologic and hematologic compartments of the 3 patients with Roifman syndrome and performed RNA sequencing to unravel important splicing defects in both cell lineages. Results: The patients exhibited a dramatic reduction in B‐cell numbers, with differentiation halted at the transitional B‐cell stage. Despite abundant B‐cell activating factor availability, development past this B‐cell activating factor–dependent stage was crippled, with disturbed minor splicing of the critical mitogen‐activated protein kinase 1 signaling component. In the hematologic compartment patients with Roifman syndrome demonstrated defects in megakaryocyte differentiation, with inadequate generation of proplatelets. Platelets from patients with Roifman syndrome were rounder, with increased tubulin and actin levels, and contained increased &agr;‐granule and dense granule markers. Significant minor intron retention in 354 megakaryocyte genes was observed, including DIAPH1 and HPS1, genes known to regulate platelet and dense granule formation, respectively. Conclusion: Together, our results provide novel molecular and cellular data toward understanding the immunologic and hematologic features of Roifman syndrome. Graphical abstract: Figure. No caption available.

Cytotoxic T-lymphocyte-associated protein 4-Ig effectively controls immune activation and inflammatory disease in a novel murine model of leaky severe combined immunodeficiency

Background Severe combined immunodeficiency can be caused by loss‐of‐function mutations in genes involved in the DNA recombination machinery, such as recombination‐activating gene 1 (RAG1), RAG2, or DNA cross‐link repair 1C (DCLRE1C). Defective DNA recombination causes a developmental block in T and B cells, resulting in high susceptibility to infections. Hypomorphic mutations in the same genes can also give rise to a partial loss of T cells in a spectrum including leaky severe combined immunodeficiency (LS) and Omenn syndrome (OS). These patients not only experience life‐threatening infections because of immunodeficiency but also experience inflammatory/autoimmune conditions caused by the presence of autoreactive T cells. Objective We sought to develop a preclinical model that fully recapitulates the symptoms of patients with LS/OS, including a model for testing therapeutic intervention. Methods We generated a novel mutant mouse (Dclre1cleaky) that develops a LS phenotype. Mice were monitored for diseases, and immune phenotype and immune function were evaluated by using flow cytometry, ELISA, and histology. Results Dclre1cleaky mice present with a complete blockade of B‐cell differentiation, with a leaky block in T‐cell differentiation resulting in an oligoclonal T‐cell receptor repertoire and enhanced cytokine secretion. Dclre1cleaky mice also had inflammatory symptoms, including wasting, dermatitis, colitis, hypereosinophilia, and high IgE levels. Development of a preclinical murine model for LS allowed testing of potential treatment, with administration of cytotoxic T‐lymphocyte‐associated protein 4‐Ig reducing disease symptoms and immunologic disturbance, resulting in increased survival. Conclusion These data suggest that cytotoxic T‐lymphocyte‐associated protein 4‐Ig should be evaluated as a potential treatment of inflammatory symptoms in patients with LS and those with OS.