Basic calcium phosphate (BCP) crystals are associated with severe osteoarthritis and acute periarticular inflammation. Three main forms of BCP crystals have been identified from pathological tissues: octacalcium phosphate, carbonate-substituted apatite, and hydroxyapatite. We investigated the proinflammatory effects of these BCP crystals in vitro with special regard to the involvement of the NLRP3–inflammasome in THP-1 cells, primary human monocytes and macrophages, and mouse bone marrow-derived macrophages (BMDM). THP-1 cells stimulated with BCP crystals produced IL-1β in a dose-dependent manner. Similarly, primary human cells and BMDM from wild-type mice also produced high concentrations of IL-1β after crystal stimulation. THP-1 cells transfected with short hairpin RNA against the components of the NLRP3 inflammasome and mouse BMDM from mice deficient for NLRP3, apoptosis-associated speck-like protein, or caspase-1 did not produce IL-1β after BCP crystal stimulation. BCP crystals induced macrophage apoptosis/necrosis as demonstrated by MTT and flow cytometric analysis. Collectively, these results demonstrate that BCP crystals induce IL-1β secretion through activating the NLRP3 inflammasome. Furthermore, we speculate that IL-1 blockade could be a novel strategy to inhibit BCP-induced inflammation in human disease.
Recently, associations were found between several autoimmune diseases and functional variants of interleukin‐23 receptor (IL23R) gene; here, we studied the possible association of nine polymorphisms of IL23R with ankylosing spondylitis (AS) and with Sjögren syndrome (SS). In our study, we genotyped groups of patients with AS (n = 206), SS (n = 156) and healthy controls (n = 235) for rs11805303, rs10889677, rs1004819, rs2201841, rs11209032, rs11209026, rs10489629, rs7517847 and rs7530511 variants using PCR‐RFLP methods. We observed significant increase in the carriage of the T allele of rs11805303 and the A allele of rs1004189 in the AS group compared with the controls. For the rs10889677 variant, the prevalence of the AA genotype and for the rs2201841, the CC genotype showed a more than two‐fold increase in the AS group compared with the controls. By contrast, the GA heterozygous genotype of rs11209026 variant showed a significant decrease in AS patients compared with controls. Haplotype analysis revealed association of four IL23R haplotypes with AS. There was no difference in the distribution of any of the examined IL23R variants between controls and SS patients. In conclusion, we confirmed the susceptibility or protective associations of IL23R polymorphisms with AS in a Hungarian population and first demonstrated the involvement of the rs11805303 intronic single nucleotide polymorphisms, which was tested so far only for other autoimmune diseases.
We confirmed reported associations of ARTS1 gene polymorphisms with AS in a Hungarian cohort study. We found HLA-B*2705 as the predominant subtype in Hungarian AS patients in accord with other studies on Caucasian populations. Our results suggest that the ARTS1 gene variants together with HLA-B27 strongly contribute to disease susceptibility in patients with AS.
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