Amelioration of adjuvant-induced arthritis by carvacrol and Lactobacillus rhamnosus: role of pro-inflammatory cytokines and T cell-mediated inflammation.

Rheumatoid arthritis (RA) is an ongoing, chronic, and systemic autoimmune disorder that affects connective tissues, one or more joints, cartilage, and bones. Recent researches have reported that carvacrol and probiotics can be used to ameliorate inflammatory disorders due to their anti-inflammatory and immune-modulatory properties. Therefore, this research was aimed to evaluate the effects of carvacrol and lactobacillus rhamnosus (L. rhamnosus) in the treatment of an animal model of rheumatoid arthritis, adjuvant-induced arthritis (AIA). Carvacrol and L. rhamnosus significantly diminished the severity levels of AIA, which was along with a reduction in the inflammatory cell populations in the synovial tissue. Additionally, carvacrol and L. rhamnosus significantly downregulated disease-related cytokines as well as an increase in the anti-inflammatory cytokines in compared to control groups. Furthermore, carvacrol and L. rhamnosus downregulated the differentiation of T-helper 1 (Th1) and Th17 cells while induced cell differentiation via regulating their key transcription factors. The current study demonstrated carvacrol and L. rhamnosus improved clinical and laboratory factors in the treatment of AIA.