ABSTRACT
Clofazimine (CFZ) is a poorly soluble antibiotic and anti-inflammatory drug indicated for the treatment of leprosy. In spite of its therapeutic value, CFZ therapy is accompanied by the formation of drug biocrystals that accumulate within resident tissue macrophages, without obvious toxicological manifestations. Therefore, to specifically elucidate the off-target consequences of drug bioaccumulation in macrophages, we compared the level of inflammasome activation in CFZ-accumulating organs (spleen, liver and lung) in mice after 2 and 8 weeks of CFZ treatment when the drug exists in soluble and insoluble (biocrystalline) forms, respectively. Surprisingly, the results showed a drastic reduction in caspase 1 and interleukin-1ß (IL-1ß) cleavage in the livers of mice treated with CFZ for 8 weeks (8-week-CFZ-treated mice) compared to 2-week-CFZ-treated and control mice, which was accompanied by a 3-fold increase in hepatic IL-1 receptor antagonist (IL-1RA) production and a 21-fold increase in serum IL-1RA levels. In the lung and spleen, IL-1ß cleavage and tumor necrosis factor alpha expression were unaffected by soluble or biocrystal CFZ forms. Functionally, there was a drastic reduction of carrageenan- and lipopolysaccharide-induced inflammation in the footpads and lungs, respectively, of 8-week-CFZ-treated mice. This immunomodulatory activity of CFZ biocrystal accumulation was attributable to the upregulation of IL-1RA, since CFZ accumulation had minimal effect in IL-1RA knockout mice or 2-week-CFZ-treated mice. In conclusion, CFZ accumulation and biocrystal formation in resident tissue macrophages profoundly altered the host's immune system and prompted an IL-1RA-dependent, systemic anti-inflammatory response.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Clofazimine/pharmacology , Inflammasomes/immunology , Interleukin-1 Receptor Accessory Protein/biosynthesis , Macrophages/drug effects , Animals , Carrageenan , Caspase 1/metabolism , Inflammation/drug therapy , Interleukin-1 Receptor Accessory Protein/genetics , Interleukin-1beta/metabolism , Lipopolysaccharides , Liver/metabolism , Lung/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Signal Transduction/immunology , Spleen/metabolism , Transcriptional Activation/drug effects , Tumor Necrosis Factor-alpha/metabolismABSTRACT
OBJECTIVE: To investigate interleukin (IL) 1 receptor accessory protein (IL1RAcP) expression in the eutopic endometrium of women with endometriosis. DESIGN: Retrospective study. SETTING: Human reproduction research laboratory. PATIENT(S): Sixty-six women with endometriosis and 60 healthy women with no laparoscopic evidence of endometriosis. INTERVENTION(S): Endometrial tissue samples were obtained during laparoscopic surgery. MAIN OUTCOME MEASURE(S): IL1RAcP protein expression was analyzed by immunohistochemistry, Western blot, and ELISA, and IL1RAcP mRNA expression was analyzed by quantitative real-time polymerase chain reaction. RESULT(S): This study showed a significant downregulation of soluble (s)IL1RAcP expression in the eutopic endometrium of women with endometriosis compared to normal women, occurring at the protein or mRNA level. This finding appeared to vary according to endometriosis stage, being more obvious in the earliest (I and II) than the latest (III and IV) stages of the disease. However, the membrane-bound IL1RAcP did not show any noticeable endometriosis-related change, neither at the protein or mRNA level. CONCLUSION(S): In view of the wide spectrum of IL-1 inflammatory and growth-promoting effects, downregulation of sIL1RAcP, which is known for inhibiting IL1, indicates a profound defect in the capability of endometrial cells of women with endometriosis to counterregulate IL-1 effects and may represent an important mechanism underlying the ability of these cells to implant and develop into host tissues.
