Serum levels of anti-Fcγ receptor IIB/C antibodies are increased in patients with systemic sclerosis

GWAS for systemic sclerosis identifies six novel susceptibility loci including one in the Fcγ receptor region

Here we report the largest Asian genome-wide association study (GWAS) for systemic sclerosis performed to date, based on data from Japanese subjects and comprising of 1428 cases and 112,599 controls. The lead SNP is in the FCGR/FCRL region, which shows a penetrating association in the Asian population, while a complete linkage disequilibrium SNP, rs10917688, is found in a cis-regulatory element for IRF8. IRF8 is also a significant locus in European GWAS for systemic sclerosis, but rs10917688 only shows an association in the presence of the risk allele of IRF8 in the Japanese population. Further analysis shows that rs10917688 is marked with H3K4me1 in primary B cells. A meta-analysis with a European GWAS detects 30 additional significant loci. Polygenic risk scores constructed with the effect sizes of the meta-analysis suggest the potential portability of genetic associations beyond populations. Prioritizing the top 5% of SNPs of IRF8 binding sites in B cells improves the fitting of the polygenic risk scores, underscoring the roles of B cells and IRF8 in the development of systemic sclerosis. The results also suggest that systemic sclerosis shares a common genetic architecture across populations.

Enrichr in silico analysis of MS-based extracted candidate proteomic biomarkers highlights pathogenic pathways in systemic sclerosis

Systemic sclerosis (SSc) is a rheumatic disease characterised by vasculopathy, inflammation and fibrosis. Its aetiopathogenesis is still unknown, and the pathways/mechanisms of the disease are not clarified. This study aimed to perform in silico analysis of the already Mass Spectrometry (MS)-based discovered biomarkers of SSc to extract possible pathways/mechanisms implicated in the disease. We recorded all published candidate MS-based found biomarkers related to SSc. We then selected a number of the candidate biomarkers using specific criteria and performed pathway and cellular component analyses using Enrichr. We used PANTHER and STRING to assess the biological processes and the interactions of the recorded proteins, respectively. Pathway analysis extracted several pathways that are associated with the three different stages of SSc pathogenesis. Some of these pathways are also related to other diseases, including autoimmune diseases. We observe that these biomarkers are located in several cellular components and implicated in many biological processes. STRING analysis showed that some proteins interact, creating significant clusters, while others do not display any evidence of an interaction. All these data highlight the complexity of SSc, and further investigation of the extracted pathways/biological processes and interactions may help study the disease from a different angle.

Dendritic cells in systemic sclerosis: Advances from human and mice studies

Systemic sclerosis (SSc) is a complex heterogeneous fibrotic autoimmune disease with an unknown exact etiology, and characterized by three hallmarks: fibrosis, vasculopathy, and immune dysfunction. Dendritic cells (DCs) are specialized cells in pathogen sensing with high potency of antigen presentation and capable of releasing mediators to shape the immune response. Altered DCs distributions and their impaired functions may account for their role in breaking the immune tolerance and driving inflammation in SSc, and the direct contribution of DCs in promoting endothelial dysfunction and fibrotic process has only begun to be understood. Plasmacytoid dendritic cells in particular have been implicated due to their high production of type I interferon as well as other cytokines and chemokines, including the pro-inflammatory and anti-angiogenic CXCL4. Furthermore, a deeper understanding of human and mouse DC biology has clarified their identification and function in different tissues, and novel DC subsets have only recently been discovered. In this review, we highlight key findings and recent advances exploring DC role in the pathogenesis of SSc and other related autoimmune diseases, and consideration of their potential use as targeted therapy in SSc.