BACKGROUND: Osteoarthritis (OA) is a common worldwide disease induced by a wide range of biochemical processes, mainly inflammation and degradation of collagen. The aim of this study, was to describe the effect of a multistrain probiotic (PB) and chondroitin sulfate (CS), administered separately or in combination, on the expression of Ptgs2, Tgfb1 and Col2a1 during monoiodoacetate-induced OA in male rats. METHODS: OA was induced in male rats by injecting monoiodoacetate in right hind knee. Therapeutic groups received 3 mg/kg of CS for 28 days and/or 1.4 g/kg of multistrain PB for 14 days. Knee cartilage were taken 30 days after monoiodoacetate injection. RNA was extracted and the expression of Ptgs2, Tgfb1 and Col2a1 were analyzed using SYBR Green 1-step real-time quantitative polymerase chain reaction. RESULTS: Induction of OA caused an upregulation in Ptgs2, Tgfb1 expression, and downregulation of Col2a1. Separate administration of PB and CS reduced Ptgs2 and Tgfb1 expressions. Their combined administration significantly decreased the expression of these pro-inflammatory cytokines, comparable to controls. Expression of Col2a1 showed similar behaviour, with upregulation in therapeutic group with separate administration and the cumulative effects in case of co-administration. CONCLUSIONS: The multistrain PB diet may offer a perspective to improve the standard treatment of OA and, necessitates further investigation with clinical trials.<br>