Pro-inflammatory effects of human apatite crystals extracted from patients suffering from calcific tendinopathy

Abstract Background Calcific tendonitis of the rotator cuff is due to carbonated apatite deposits in shoulder tendons. During evolution disease, an acute inflammatory episode may occur leading disappearance calcification. Although hydroxyapatite crystal-induced inflammation has been previously studied with synthetic crystals, no data are available calcifications extracted from patients suffering calcific tendinopathy. The objective study was explore properties human and pathways involved. Methods Human were used vitro stimulate monocytes macrophages, myeloid cell line THP-1, tenocytes. release IL-1?, IL-6, IL-8 by cells quantified ELISA. gene expression pro- anti-inflammatory cytokines evaluated quantitative PCR. NF-kB activation NLRP3 involvement assessed THP-1 using a inhibitor caspase-1 inhibitor. then vivo mouse air pouch model. Results able induce significant IL-1? when incubated monocytes, only if they first primed LPS (monocytes macrophages) or PMA (THP-1). Stimulation led similar levels compared although these significantly inferior macrophages. patient’s crystals enhanced mRNA pro-IL-1? , as well IL-18 TGF? IL-6 TNF? not. production reduced inhibition indicating role inflammasome. In vivo, injection increase membrane thickness overexpression observed for hydroxyapatite. Conclusions As hydroxyapatite, response resulting after through some experiments, induction lower apatite. Differences size, shape, protein content explain this observation.