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OBJECTIVES: Interferon regulatory factor 5 (IRF5) is a major regulator of type I interferon induction and is also critical to produce pro-inflammatory cytokines. An influence of IRF5 genetic variants on the increased risk of immune-mediated diseases has been described. Accordingly, we aimed to evaluate the implication of IRF5 in the pathogenesis of Immunoglobulin-A vasculitis (IgAV), an inflammatory vascular pathology. METHODS: Three tag genetic variants (rs2004640, rs2070197 and rs10954213), representative of 3 different haplotype blocks within IRF5, were genotyped in 372 Caucasian patients with IgAV and 876 sex and ethnically matched healthy controls by TaqMan assays. RESULTS: No significant differences in the genotype and allele frequencies between patients with IgAV and healthy controls were observed when each IRF5 polymorphism was evaluated independently. Likewise, no significant differences between patients with IgAV and healthy controls were found when we assessed the three IRF5 polymorphisms combined, conforming haplotypes. In addition, there were no significant differences in genotype, allele and haplotype frequencies of IRF5 when patients with IgAV were stratified according to the age at disease onset or to the presence/absence of gastrointestinal or renal manifestations. CONCLUSIONS: Our results do not support an influence of IRF5 on the pathogenesis of IgAV.

Data from a small series suggested that the Interleukin 1 beta (IL1ß) rs16944 polymorphism may be associated with severe renal involvement and persistent renal damage (renal sequelae) in Henoch-Schönlein purpura (HSP). To confirm this association, we assessed the largest cohort of Caucasian HSP patients ever considered for genetic studies.338 Spanish HSP patients and 635 sex and ethnically matched controls were recruited in this study. All patients were required to have had at least 6 months' follow-up. Patients and controls were genotyped for IL1β rs16944 by TaqMan genotyping assay.No differences between IL1β rs16944 genotype or allele frequencies were found either in the case/control study or when HSP patients were stratified according to the age at disease onset, presence of nephritis or gastrointestinal manifestations. Nevertheless, 4 (25%) of the 16 HSP patients who developed severe renal manifestations carried the TT genotype versus 29 (9%) of 322 who did not develop this complication (p=0.01, OR=5.48, 95% CI: 1.01-28.10). Accordingly, patients carrying the mutant T allele had an increased risk of developing severe nephropathy (p=0.016, OR=2.35, 95% CI: 1.09-5.07). Additionally, a significant increase of the TT genotype was observed in patients with persistent renal damage when compared with those patients without this complication (25% versus 8.6%, respectively; p=0.0035, OR=4.90, 95% CI: 1.26- 18.51). Moreover, renal sequelae were more common in patients carrying the mutant T allele (p=0.0076, OR=2.20, 95% CI: 1.17-4.14).Our results support that the IL1ß rs16944 polymorphism may be a potential marker of severe renal manifestations and renal sequelae in HSP.

OBJECTIVES: Cytokines signaling pathway genes represent a key component of the genetic network implicated in the pathogenesis of immunoglobulin-A vasculitis (IgAV), an inflammatory vascular pathology. Interleukin (IL)17A is described as a genetic risk locus for some autoimmune diseases, such as giant cell arteritis and spondyloarthritis. Accordingly, we aimed to determine the potential influence of IL17A on the pathogenesis of IgAV. METHODS: Five IL17A tag polymorphisms (rs4711998, rs8193036, rs3819024, rs2275913 and rs7747909), which cover the major variability of this gene, were genotyped in 360 Caucasian patients with IgAV and 1,003 sex and ethnically matched healthy controls using TaqMan probes. RESULTS: No statistically significant differences between patients with IgAV and healthy controls were observed when each IL17A genetic variant was analysed independently. Similarly, no statistically significant differences between patients with IgAV and healthy controls were found when the five IL17A polymorphisms were evaluated combined conforming haplotypes. In addition, there were no statistically significant differences in genotype, allele and haplotype frequencies of IL17A when patients with IgAV were stratified according to the age at disease onset or to the presence/absence of gastrointestinal or renal manifestations. CONCLUSIONS: Our results do not support an influence of IL17A on the pathogenesis of IgAV.

[Introduction] To determine whether the PTPN22 (protein tyrosine phosphatase nonreceptor 22)/CSK (c-src tyrosine kinase) pathway is implicated in the susceptibility and clinical heterogeneity of Henoch-Schönlein purpura (HSP) in the largest series of Caucasian HSP patients ever assessed for genetic studies., [Methods] A set of 329 Spanish patients diagnosed with HSP fulfilling the American College of Rheumatology and the Michel et al. classification criteria and 515 sex and ethnically matched controls were recruited in this study. Two well-known CSK (CSK rs34933034 and CSK rs1378942) and two functional PTPN22 (PTPN22 rs2476601 (R620W) and PTPN22 rs33996649 (R263Q)) polymorphisms, previously associated with autoimmunity, were genotyped with TaqMan single nucleotide polymorphism (SNP) genotyping assays., [Results] No significant differences in the genotype and allele frequencies between HSP patients and controls were observed when the CSK rs34933034, CSK rs1378942, PTPN22 rs2476601 (R620W) and PTPN22 rs33996649 (R263Q) polymorphisms were analyzed independently. In keeping with this observation, no significant differences were found when we assessed these polymorphisms combined conforming haplotypes. In addition, there were no differences in the allele or genotype frequencies when HSP patients were stratified according the age at disease onset, sex, presence of arthralgia/arthritis, nephritis or gastrointestinal manifestations., [Conclusions] Our results do not support association between PTPN22/CSK and HSP., This study was supported by a grant from “Fondo de Investigaciones Sanitarias” PI12/00193 (Spain). RLM is a recipient of a Sara Borrell postdoctoral fellowship from the Instituto de Salud Carlos III at the Spanish Ministry of Health (Spain) (CD12/00425). FG and BU are supported by funds from the RETICS Program (RIER) (RD12/0009/0013).

López-Mejías, Raquel et al., [Introduction] A study was conducted to determine whether the human leukocyte antigen (HLA) B alleles are implicated in the susceptibility to Henoch-Schönlein purpura (HSP) in the largest series of Caucasian HSP patients ever assessed for genetic studies., [Methods] The study population was composed of 349 Spanish patients diagnosed with HSP fulfilling the American College of Rheumatology and the Michel et al. classification criteria, and 335 sex and ethnically matched controls. HLA-B phenotypes were determined by sequencing-based typing (SBT) and analyzed by chi-square or Fisher exact test., [Results] A statistically significant increase of HLA-B*41:02 allele in HSP patients when compared with controls was found (8.3% versus 1.5% respectively; P = 0.0001; OR (odds ratio) =5.76 [2.15-19.3]). These results remained statistically significant after adjusting for Bonferroni correction (P = 0.0028). An internal validation also confirmed the susceptibility effect on HSP associated with HLA-B*41:02 (OR = 5.70 [1.98-16.44]). Since a former study described an association between HLA-DRB1*01:03 and HSP susceptibility, we also evaluated the implication of HLA-B*41:02 independently of HLA-DRB1*01:03. Interestingly, the association remained statistically significant (P = 0.0004, OR = 4.97 [1.8-16.9]). No HLA-B association with specific HSP clinical features was found., [Conclusions] Our study indicates that HLA-B*41:02 is associated with the susceptibility to HSP in Spanish patients irrespective of HLA-DRB1 status., This study was supported by a grant from ‘Fondo de Investigaciones Sanitarias’ PI12/00193 (Spain). RLM is a recipient of a Sara Borrell postdoctoral fellowship from the Instituto de Salud Carlos III at the Spanish Ministry of Health (Spain) (CD12/00425). FG and BU are supported by funds from the RETICS Program (RIER) (RD12/0009/0013).