Trivalent chromium supplementation ameliorates adjuvant induced rheumatoid arthritis through up-regulation of FOXP3 and decrease in synovial Cathepsin G expression

BACKGROUND: Rheumatoid arthritis (RA) is a known debilitating autoimmune disease. Immune-suppressants that are used for disease treatment have serious side effects, therefore, trivalent chromium (Cr (III)); which has shown evidence of its influences on some inflammatory pathways and cytokines; was used in this study for the first time to be assessed for its therapeutic effect in RA rat model and was compared to prednisolone in a trial to find a treatment with lesser side effects. METHODS: Adult male albino rats were randomly divided into four groups: normal, untreated RA, prednisolone treated RA (1.25 mg/kg/day) and Cr (III) treated RA groups (80 μg/kg/day), induction of RA was done by subcutaneous complete Freund adjuvant injection. Study duration was 4 weeks throughout which arthritis scoring and weight measurement were pursued. Histopathological examination and immunohistochemical FOXP3 assessment were done for joint biopsies. Serum inflammatory markers (interleukin 17, interleukin 10, CRP) and synovial erosive arthritis marker (Cathepsin G) were measured. HDL and non-HDL cholesterol were estimated as well. RESULTS: Cr (III) treatment showed marked clinical and histopathological improvement, also astonishing anti-inflammatory effects (increase in FOXP3 expression and interleukin 10, with decrease in interleukin 17, CRP and synovial Cathepsin G) to the extent that Cr (III) effects on inflammation abolishment were comparable to that of prednisolone and even better at some aspects. Moreover, Cr (III) was protective from side effects, i.e., weight gain and dyslipidemia that were seen with prednisolone treatment. CONCLUSIONS: Cr (III) is promising in treating RA and it lacks some side effects of accustomed immune-modulatory agents including prednisolone. Further experimental studies and clinical trials should be held to see the efficacy of Cr (III) in different doses and to assess its long term side effects when used for rheumatoid arthritis and other autoimmune diseases treatment.