Τhe genetics of juvenile idiopathic arthritis: Searching for new susceptibility loci

Genetic association between the PTPN22, IRF5 and TYK2 gene variants and susceptibility to juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) refers to a group of chronic childhood arthropathies of unknown etiology. In the present study, the genetic association between the variants in PTPN22, IRF5 and TYK2 genes and susceptibility to JIA was investigated. The distributions of 16 variants in PTPN22, IRF5 and TYK2 genes were analyzed by direct sequencing in 378 patients with JIA and 378 healthy controls. Odds ratios and 95% confidence intervals were used to evaluate the association between the gene variants and JIA. The gene-gene interactions were investigated using multifactor dimensionality reduction. All allelic and dominant models of PTPN22 rs1214414, rs1214418, rs1746853, rs3765598 and rs3811021 were significantly associated with JIA risk (P<0.05). IRF5 rs10954213 in both allelic and dominant models, as well as the allelic model of rs2004640, was significantly related to JIA risk (P<0.05). In addition, the allelic, recessive and dominant models of TYK2 rs280500, rs280519, rs2304256 and rs12720270 were significantly related to JIA risk (P<0.05). In addition, three haplotypes (H_{C A G T C C}, H_{C A G T T C} and H_{C G T T C T} ) in PTPN22 gene, three haplotypes (H_{D T A A}, H_{I T A C} and H_{D T G C}) in IRF5 gene and two haplotypes (H_{A G G A T} and H_{G A G G T}) in TYK2 gene were associated with the risk of JIA (P<0.05). Furthermore, a three-way interaction between IRF5 rs10954213, rs2004640 and PTPN22 rs1214414 was shown to be associated with JIA risk. In conclusion, PTPN22 rs1214418, rs1746853, rs3765598, IRF5 rs2004640, TYK2 rs280500, rs2304256 and a three-way interaction between IRF5 rs10954213, rs2004640 and PTPN22 rs1214414 may be risk factors for JIA.

IL-1 signaling pathway molecules as key markers in childhood asthma

OBJECTIVE

The prevalence of childhood asthma has been increasing in recent years. This study aims to investigate the involvement of the key molecules of IL-1 (interleukin-1) signaling pathways in pediatric patients with asthma.

METHODS

Differentially expressed genes (DEGs) associated with IL-1 signaling pathways were identified with RNA-seq from peripheral blood samples collected from asthmatic or healthy children and were further verified in clinical peripheral blood samples. Cellular models and asthmatic mice were subsequently developed to validate the identified asthmatic markers.

RESULTS

Among the DEGs identified by RNA-seq, eight signal transducers associated with the IL-1 signaling network, namely IL-1RN, IL-1β, IL-1RAP, IRAK3, IL-1R1, MYD88, IRAK2, and PELI1, were found to be substantially upregulated in children with asthma. Interestingly, a significant serially increased expression of four genes (IL-1RN, IL-1RAP, IRAK3, and PELI1) was observed in healthy subjects, patients with chronic persistent asthma and patients with acute exacerbation asthma. In particular, these four genes were continuously overexpressed in recurrent patients. A significant induction of the above four genes was then observed in house dust mite (HDM)-stimulated peripheral blood mononuclear cells (PBMCs) and ovalbumin (OVA)-induced asthmatic mice. In addition, a time-dependent induction of IL-1RAP and PELI1 was also detected in HDM-treated THP-1 cells, an acute monocytic leukemia cell line.

CONCLUSIONS

These results demonstrate that IL-1RN, IL-1RAP, IRAK3, and PELI1, which are signal transducers of the IL-1 signaling pathway, could serve as biomarkers for the pathogenesis of childhood asthma and for potential therapeutic targets of asthma.

The Multi-Omics Architecture of Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is highly heterogeneous in terms of etiology and clinical presentation with ambiguity in JIA classification. The advance of high-throughput omics technologies in recent years has gained us significant knowledge about the molecular mechanisms of JIA. Besides a minor proportion of JIA cases as monogenic, most JIA cases are polygenic disease caused by autoimmune mechanisms. A number of HLA alleles (including both HLA class I and class II genes), and 23 non-HLA genetic loci have been identified of association with different JIA subtypes. Omics technologies, i.e., transcriptome profiling and epigenomic analysis, contributed significant knowledge on the molecular mechanisms of JIA in addition to the genetic approach. New molecular knowledge on different JIA subtypes enables us to reconsider the JIA classification, but also highlights novel therapeutic targets to develop a cure for the devastating JIA.

Usefulness of complex bacteriological and serological analysis in patients with spondyloarthritis

Spondyloarthritis (SpA) is a group of associated chronic systemic inflammatory immune-mediated rheumatic diseases affecting axial and peripheral joints and entheses. The aim of the present study was to identify what parameters are useful to determine in order to better understand the correlation between the disease activity/severity and the microbiological results/immune status against intestinal and/or urogenital pathogens. Microorganisms known to trigger SpA, including Klebsiella spp., Yersinia spp., Salmonella spp., Campylobacter spp. and Chlamydia spp., were analyzed in various specimens (stool, urine, synovial fluid and serum) collected from 27 randomly selected SpA patients and 26 healthy controls using a combined direct and indirect approach relying on conventional culture technique and nucleic acid-based assays together with serological testing by ELISA. Although Escherichia coli derived from phylogroup A prevailed in the gut microflora of the patients and controls, differences were observed regarding the representatives of the other phylogroups with a higher prevalence of E.coli members of phylogenetic group B1 in the stool specimens of patients. Antibodies against the targeted species were detected in SpA patients and controls, and the serological profiles of the former were more diverse and complex. In conclusion, the detection of anti-bacterial antibodies combined with other specific laboratory investigations should be more extensively used to monitor SpA patients in association with their symptoms and in order to determine and administer more effective therapeutics.

Single Nucleotide Polymorphism of TYK2 Gene and Susceptibility to Rheumatoid Arthritis in Iranian Population

BACKGROUND

Rheumatoid Arthritis (RA) is a debilitating disorder in which the immune system mainly targets the synovial tissue. Janus kinase family including tyrosine kinase 2 (TYK2) is one of the crucial mediators of the downstream signaling pathway of inflammatory cytokines that further contributes to RA pathogenesis. In this study, the association of TYK2 gene rs34536443 polymorphism, which may affect the function of TYK protein and, hence, the inflammatory settings, with RA susceptibility was investigated. Moreover, its correlation with demographic and serological features of the patients was assessed.

METHODS

In the present study, 700 RA patients and 700 sex, age and ethnicity-matched healthy individuals as the control group were included. MGB TaqMan real-time allelic discrimination method was used to determine the rs34536443 polymorphism. Rheumatoid factor, anti-cyclic citrullinated peptide antibody, erythrocyte sedimentation rate and C-reactive protein were also measured.

RESULTS

The frequency of rs34536443 minor allele (C allele) was not different between patients and control group [1.7 vs. 2.61 percent, OR (95% CI)=1.35 (0.78-2.33);p=0.27]. There was not a statistically significant association between rs34536443 genotypes and RA susceptibility. Genotypes of rs34536443 polymorphism were associated nor with demographic neither with serological features of RA patients.

CONCLUSION

In the present study, there was not any association between TYK2 gene rs34536443 polymorphism with either disease susceptibility, demographic and serological features of Iranian RA patients. These findings are not compatible with previous works from other ethnicities, further supporting the role of genetics in disease susceptibility.