Cutaneous syndrome is a relevant issue not only among allergic diseases but also among autoimmune disorders. Urticaria is a widespread problem, as its prevalence among the population can reach up to 9%. The main goal of the article is to analyze the role of platelet-activating factor in patients with
hypersensitive vasculitis, autoimmune, and allergic urticaria. Urticarial rash is at the intersection of allergic and autoimmune diseases, where is observed active immunopathogenetic influence of plateletactivating factor in the initiation and maintenance of systemic vasculitis, including hypersensitive/urticarial and cryoglobulinemic vasculitis Considering the significant role of this factor in the pathogenesis of hypersensitive vasculitis and allergic reactions, selective targeting of plateletactivating factor represents a promising therapeutic approach. These include plateletactivating factor receptor antagonists such as
rupatadine and apafant, as well as plateletactivating factor acetylhydrolase inhibitors, enzymes responsible for platelet-activating factor degradation. Targeted intervention on platelet-activating factor holds promise for the improving the quality of life of patients with hypersensitive vasculitis, autoimmune disorders, and allergic urticaria.
Keywords: platelet activation factor, hypersensitive vasculitis, urticaria.
Introduction: Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. Although RA is chiefly associated with HLA class II, nevertheless some HLA class I associations have also been observed. These molecules present antigenic peptides to CD8+ T lymphocytes and natural killer cells. HLA-I molecules bind their peptide cargo (8–10 amino acids long) in the endoplasmic reticulum. Peptides longer than 10 amino acids are trimmed by the endoplasmic reticulum aminopeptidases ERAP1 and ERAP2 to fit the peptide binding groove of the HLA-I molecule. Here, we investigated the possible association of ERAP1 and ERAP2 polymorphisms with RA, and also any possible correlation between serum levels of the ERAP2 protein with disease severity.
Methods: We used Real-Time PCR to genotype ERAP1 and ERAP2 and ELISA test to detect ERAP2 protein.
Results: We found significant associations of ERAP1 rs30187, rs27044, and rs26618, as well as ERAP2 rs2248374, with susceptibility to RA. ERAP1 rs26653 and ERAP2 rs2248374 were also associated with the Disease Activity Score (DAS28), and some polymorphisms were also associated with anti-citrullinated protein or anti-mutated citrullinated vimentin antibodies. RA patients secreted higher concentrations of ERAP2 than controls. Patients with mild disease activity (DAS28 < 3.2) released a concentration of ERAP2 four times lower than that of patients with severe disease activity (DAS28 > 5.1). We detected a higher level of ERAP2 in rheumatoid factor (RF)-positive patients than in RF-negative patients. ERAP2 concentration above 5.85 ng/mL indicated a severe phase of RA.
Conclusions: Some ERAP1 and ERAP2 polymorphisms seem to be related to susceptibility to RA or the severity of the disease. The ERAP2 protein tested in serum could be a valuable biomarker of RA severity.