The IL‐13/IL‐4Rα axis is involved in tuberculosis‐associated pathology

Human tuberculosis (TB) is a leading global health threat and still constitutes a major medical challenge. However, mechanisms governing tissue pathology during post‐primary TB remain elusive, partly because genetically or immunologically tractable animal models are lacking. In human TB, the demonstration of a large relative increase in interleukin (IL)‐4 and IL‐13 expression, which correlates with lung damage, indicates that a subversive T helper (TH)2 component in the response to Mycobacterium tuberculosis (Mtb) may undermine protective immunity and contribute to reactivation and tissue pathology. Up to now, there has been no clear evidence regarding whether IL‐4/IL‐13‐IL‐4 receptor‐α (Rα)‐mediated mechanisms may in fact cause reactivation and pathology. Unfortunately, the virtual absence of centrally necrotizing granulomas in experimental murine TB is associated with a poor induction of a TH2 immune response. We therefore hypothesize that, in mice, an increased production of IL‐13 may lead to a pathology similar to human post‐primary TB. In our study, aerosol Mtb infection of IL‐13‐over‐expressing mice in fact resulted in pulmonary centrally necrotizing granulomas with multinucleated giant cells, a hypoxic rim and a perinecrotic collagen capsule, with an adjacent zone of lipid‐rich, acid‐fast bacilli‐containing foamy macrophages, thus strongly resembling the pathology in human post‐primary TB. Granuloma necrosis (GN) in Mtb‐infected IL‐13‐over‐expressing mice was associated with the induction of arginase‐1‐expressing macrophages. Indirect blockade of the endogenous arginase inhibitor l ‐hydroxyarginine in Mtb‐infected wild‐type mice resulted in a strong arginase expression and precipitated a similar pathology of GN. Together, we here introduce an experimental TB model that displays many features of centrally necrotizing granulomas in human post‐primary TB and demonstrate that IL‐13/IL‐4Rα‐dependent mechanisms leading to arginase‐1 expression are involved in TB‐associated tissue pathology. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Association between IL‐17F Gene Polymorphisms and Susceptibility to and Severity of Rheumatoid Arthritis (RA)

Interleukin‐17F (IL‐17F) is a novel proinflammatory cytokine. IL‐17F gene is an excellent candidate for chronic inflammatory disease. We investigated the association between rheumatoid arthritis (RA) and His161Arg (7488A/G; rs763780) and Glu126Gly (7383A/G; rs2397084) polymorphism of IL‐17F gene. The gene polymorphisms in 220 Polish patients with RA and 106 healthy subjects were amplified by polymerase chain reaction with restriction endonuclease mapping. Overall, the polymorphisms of the IL‐17F gene were not correlated with susceptibility to RA in Polish population. However, the IL‐17F His161Arg variant was associated with parameters of disease activity, such as number of tender joints, HAQ score or DAS‐28‐CRP. Moreover, our findings have shown that Glu126Gly IL‐17F gene polymorphism may be correlated with longer disease duration in patients with RA. Our results for the first time showed the relationship between IL‐17F gene polymorphisms and severity of RA.     

The Immunologic Role of IL-17 in Psoriasis and Psoriatic Arthritis Pathogenesis

Psoriasis is a chronic, immune-mediated, inflammatory disease that is pathogenically driven by proinflammatory cytokines. This article reviews the immunologic role of interleukin (IL)-17, the major effector cytokine in the pathogenesis of psoriatic disease, along with the rationale for targeting the IL-17 cytokine family (IL-17A, IL-17F, and IL-17 receptor A) in the treatment of psoriasis and psoriatic arthritis. Emerging evidence indicates that major sources of IL-17A in patients with psoriatic disease are mast cells, γδ T cells, αβ T cells, and innate lymphoid cells in lesional skin and synovial fluid. Within the skin and joints, IL-17A acts on cellular targets, including keratinocytes, neutrophils, endothelial cells, fibroblasts, osteoclasts, chondrocytes, and osteoblasts, to stimulate production of various antimicrobial peptides, chemokines, and proinflammatory and proliferative cytokines, which, in turn, promote tissue inflammation and bone remodeling. The critical importance of the IL-23/IL-17A axis to the pathogenesis of psoriatic disease has resulted in many new biologic treatments targeting these cytokines. These biologics dramatically improve skin and joint symptoms in patients with moderate-to-severe psoriasis and psoriatic arthritis.     

IL‐13Rα1 is a surface marker for M2 macrophages influencing their differentiation and function

In this study, we examined the role IL‐13 receptor alpha 1 (IL‐13Rα1) plays in macrophage differentiation and function. The findings indicate that IL‐13Rα1 is expressed on the M2 but not on the M1 subset of macrophages and specifically heterodimerizes with the IL‐4Rα chain to form a type II receptor, which controls the differentiation and function of these cells. Indeed, BM cells from IL‐13Rα1^+/+ and IL‐13Rα1^?/? mice yield equivalent numbers of macrophages when cultured under M2 polarizing conditions. However, IL‐13Rα1^?/? BM cells yield a much higher number of macrophages than IL‐13Rα1^+/+ BM cells when the differentiation is carried out under M1‐polarizing conditions. Further analyses indicated that macrophages that express IL‐13Rα1 also display surface markers associated with an M2 phenotype. In addition, the IL‐13Rα1⁺ macrophages were highly efficient in phagocytizing zymosan bioparticles both in vitro and in vivo, and supported differentiation of naïve T cells to a Th2 phenotype. Finally, when stimulated by IL‐13, a cytokine that uses the heteroreceptor, the cells were able to phosphorylate STAT6 efficiently. These previously unrecognized findings indicate that IL‐13Rα1 serves as a marker for M2 macrophages and the resulting heteroreceptor influences both their differentiation and function.     

The microRNA‐9/B‐lymphocyte‐induced maturation protein‐1/IL‐2 axis is differentially regulated in progressive HIV infection

The fine control of T‐cell differentiation and its impact on HIV disease states is poorly understood. In this study, we demonstrate that B‐lymphocyte‐induced maturation protein‐1 (Blimp‐1/Prdm1) is highly expressed in CD4⁺ T cells from chronically HIV‐infected (CHI) patients compared to cells from long‐term nonprogressors or healthy controls. Stimulation through the T‐cell receptor in the presence ofIL‐2 induces Blimp‐1 protein expression. We show here that Blimp‐1 levels are translationally regulated by microRNA‐9 (miR‐9). Overexpression of miR‐9 induces Blimp‐1 repression, restoring IL‐2 secretion in CD4⁺ T cells via reduction in the binding of Blimp‐1 to the il‐2 promoter. In CHI patients where IL‐2 expression is reduced and there is generalized T‐cell dysfunction, we show differential expression of both miR‐9 and Blimp‐1 in CD4⁺ cells compared with levels in long‐term nonprogressors. These data identify a novel miR‐9/Blimp‐1/IL‐2 axis that is dysregulated in progressive HIV infection.     

Evaluation of SNPs in miR‐146a,miR196a2 and miR‐499 as low‐penetrance alleles in German and Italian familial breast cancer cases

Recently, the SNPs rs11614913 in hsa‐mir‐196a2 and rs3746444 in hsa‐mir‐499 were reported to be associated with increased breast cancer risk, and the SNP rs2910164 in hsa‐mir‐146a was shown to have an effect on age of breast cancer diagnosis. In order to further investigate the effect of these SNPs, we genotyped a total of 1894 breast cancer cases negative for disease‐causing mutations or unclassified variants in BRCA1 and BRCA2, and 2760 controls from Germany and Italy. We compared the genotype and allele frequencies of rs2910164, rs11614913 and rs3746444 in cases versus controls of the German and Italian series, and of the two series combined; we also investigated the effect of the three SNPs on age at breast cancer diagnosis. None of the performed analyses showed statistically significant results. In conclusion, our data suggested lack of association between SNPs rs2910164, rs11614913 and rs3746444 and breast cancer risk, or age at breast cancer onset. © 2009 Wiley‐Liss, Inc.     

Analysis of miR‐146a and miR‐142‐3p as Potential Markers of Freshly Isolated or In Vitro‐Expanded Human Treg cells

Regulatory CD4⁺ T cells (Tregs) are pivotal for prevention of autoimmunity. The use of Tregs is therefore of increasing interest in in vitro drug screening assays as well as for a cytotherapy per se against autoimmune disorders. For both purposes, in vitro expansion of peripheral blood Tregs is necessary and there is an increasing need to identify novel markers that can discriminate natural thymic‐derived Tregs (tTregs) from other T cell subsets, and ideally, such markers should be stably expressed during in vitro expansion procedures. We screened for novel miRNAs differentially expressed in tTregs and identified miR‐146a and 142‐3p as possible candidates. We analysed freshly isolated naïve and activated tTregs and non‐Treg subsets after or prior to in vitro expansion. We observed a tTreg‐specific profile of these miRNAs together with FOXP3 and Helios in freshly isolated tTregs, but observed a decline in the same markers in activated tTregs as opposed to naïve tTregs. In vitro‐expanded Tregs could be identified based on FOXP3 expression, but with loss of a discriminate profile for miRNA candidates and a decline in FOXP3 when activated tTregs were expanded. Our data demonstrate miR‐146a and 142‐3p as potential miRNA markers for discrimination between non‐Treg cells and tTregs, but these miRNAs are not stable markers for in vitro‐expanded Treg cells. In addition, the loss of FOXP3 in expansion of activated tTregs has implication for in vitro use of this cell subset in immunopharmacological assays and cytotherapy as FOXP3 is pivotal for suppressive function.     

Human natural Treg microRNA signature: Role of microRNA‐31 and microRNA‐21 in FOXP3 expression

Treg are the main mediators of dominant tolerance. Their mechanisms of action and applications are subjects of considerable debate currently. However, a human microRNA (miR) Treg signature has not been described yet. We investigated human natural Treg and identified a signature composed of five miR (21, 31, 125a, 181c and 374). Among those, two were considerably under‐expressed (miR‐31 and miR‐125a). We identified a functional target sequence for miR‐31 in the 3′ untranslated region (3′ UTR) of FOXP3 mRNA. Using lentiviral transduction of fresh cord blood T cells, we demonstrated that miR‐31 and miR‐21 had an effect on FOXP3 expression levels. We showed that miR‐31 negatively regulates FOXP3 expression by binding directly to its potential target site in the 3′ UTR of FOXP3 mRNA. We next demonstrated that miR‐21 acted as a positive, though indirect, regulator of FOXP3 expression. Transduction of the remaining three miR had no direct effect on FOXP3 expression or on the phenotype and will remain the subject of future investigations. In conclusion, not only have we identified and validated a miR signature for human natural Treg, but also unveiled some of the mechanisms by which this signature was related to the control of FOXP3 expression in these cells.     

Association of IL‐4 589 C/T promoter and IL‐4RαI50V receptor polymorphism with susceptibility to HIV‐1 infection in North Indians

The clinical course and outcome of HIV‐1 infection are highly variable among individuals. Interleukin 4 (IL‐4) is a key T helper 2 cytokine with various immune‐modulating functions including induction of immunoglobulin E (IgE) production in B cells, downregulation of CCR5 and upregulation of CXCR4, the main co‐receptors for HIV. Our objective is to investigate whether single‐nucleotide polymorphisms (SNPs) in the IL‐4 promoter 589 C/T and IL‐4 Rα I50V affect the susceptibility to HIV infection and its progression to AIDS in North Indian individuals. The study population consisted of 180 HIV‐1 seropositive (HSP) stratified on the basis of disease severity (stage I, II, III), 50 HIV‐1 exposed seronegative (HES), and 305 HIV‐1 seronegative (HSN) individuals. The subjects were genotyped for IL‐4 589 C/T promoter polymorphism and IL‐4 Rα I50V by polymerase chain reaction restriction fragment length polymorphism. The results showed that IL‐4 589 C/T was not associated with the risk of HIV infection and disease progression. However, the IL‐4Rα I50 allele and genotype was significantly increased in HSP compared to HSN and HSP and was associated with risk of HIV infection. The frequency of IL‐4Rα I50 allele in the HSP group was higher than in HSN (76.11 vs. 64.75%; P = 0.000; OR = 1.734) and HES (76.11% vs. 62.00%; P = 0.007; OR = 1.953). Homozygous IL‐4Rα I50I genotype was significantly increased in HSP group compared with HSN (58.88% vs. 44.26%; P = 0.002; OR = 1.804) and HES (58.88% vs. 42.00%; P = 0.038; OR = 1.978). The present study for the first time suggests an association of IL‐4Rα I50 allele with increased likelihood of HIV‐1 infection in North Indian population. Further studies are required to confirm these findings and understand the effect of IL‐4Rα polymorphism on the outcome of HIV‐1 infection. J. Med. Virol. 81:959–965, 2009. © 2009 Wiley‐Liss, Inc.     

IL‐2 is positively involved in the development of colitogenic CD4+ IL‐7Rαhigh memory T cells in chronic colitis

IL‐2 and IL‐7 share a common γ‐chain receptor and are critical for T‐cell homeostasis. We aimed to clarify the reciprocal roles of IL‐2 and IL‐7 in the development and persistence of chronic colitis. We performed a series of adoptive transfers of IL‐2^?/? CD4⁺CD45RB^high T cells into RAG‐2^?/? mice and assessed the role of IL‐2 in the induction of IL‐7Rα on colitogenic CD4⁺ T cells and the development of chronic colitis. RAG‐2^?/? mice transferred with WT but not with IL‐2^?/? CD4⁺CD45RB^high T cells developed Th1/Th17‐mediated colitis. Consistently, re‐expression of IL‐7Rα was severely impaired on IL‐2^?/? but not on WT CD4⁺ T cells from the transferred mice. To exclude a contribution of the preclinical autoimmunity of IL‐2^?/?mice, WT Ly5.1⁺ or IL‐2^?/? Ly5.2⁺ CD4⁺CD45RB^high T cells from GFP mice previously transplanted with the same number of WT and IL‐2^?/? BM cells were transferred into RAG‐2^?/? mice. RAG‐2^?/? mice transferred with IL‐2^?/?‐derived CD4⁺CD45RB^high T cells did not develop colitis, but their splenic CD4⁺ T cells changed from effector‐memory to central‐memory type. These results show that IL‐2 is critically involved in the establishment and maintenance of IL‐7‐dependent colitogenic memory CD4⁺IL‐7Rα^high T cells.     

Analysis of Circulating miR‐1, miR‐23a,and miR‐26a in Atrial Fibrillation Patients Undergoing Coronary Bypass Artery Grafting Surgery

Atrial fibrillation (AF) is the most common arrhythmia after cardiac surgery. From a pathophysiological point of view, a myriad of factors such as trauma, atrial dilation, ischemia, mechanical myopericarditis, autonomic imbalance, loss of connexins, AF nest remodeling, inflammation, sutures, and dysfunction caused by postextracorporeal circulation can contribute to postoperative atrial fibrillation (POAF) resulting in a longer hospital stay and consequently higher cost. Recent studies showed that short fragments of RNA, called microRNA (miRNA), can contribute to the development of several cardiovascular diseases, including AF. The aim of this study was to evaluate the levels of circulating miRNAs (miR‐1, ‐23a, and ‐26a) that can be involved in POAF. Patients submitted to coronary artery bypass graft surgery were grouped in POAF (24 patients) and without POAF (24 patients). Results showed older age, longer clamp‐time, and more days in the intensive care unit as well as a longer total hospital stay in the POAF group. Preoperative levels of circulating miRNAs were similar. Analysis of miRNAs revealed significantly lower circulating levels of miRNA‐23a (P = 0.02) and ‐26a (P = 0.01) in the POAF group during the postoperative period. Receiver operating characteristic (ROC) analysis showed the area under the ROC curve of miR‐23a and miR‐26a for predicting FA was 0.63 (95% confidence interval [CI]: 0.51–0.74; P = 0.02) and 0.66 (95% CI: 0.55–0.77; P = 0.01), respectively. Our data suggests that circulating miRNA‐23a and ‐26a may be involved in the underlying biology of postoperative AF development.     

IL‐12Rβ1 Deficiency: Mutation Update and Description of the IL12RB1 Variation Database

IL‐12Rβ1 deficiency is an autosomal recessive disorder characterized by predisposition to recurrent and/or severe infections caused by otherwise poorly pathogenic mycobacteria and salmonella. IL‐12Rβ1 is a receptor chain of both the IL‐12 and the IL‐23 receptor and deficiency of IL‐12Rβ1 thus abolishes both IL‐12 and IL‐23 signaling. IL‐12Rβ1 deficiency is caused by bi‐allelic mutations in the IL12RB1 gene. Mutations resulting in premature stop codons, such as nonsense, frame shift, and splice site mutations, represent the majority of IL‐12Rβ1 deficiency causing mutations (66%; 46/70). Also every other morbid mutation completely inactivates the IL‐12Rβ1 protein. In addition to disease‐causing mutations, rare and common variations with unknown functional effect have been reported in IL12RB1. All these variants have been deposited in the online IL12RB1 variation database ( www.LOVD.nl/IL12RB1 ). In this article, we review the function of IL‐12Rβ1 and molecular genetics of human IL12RB1.