Studies on anti-inflammatory and analgesic properties of Lactobacillus rhamnosus in experimental animal models

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used for the treatment of inflammatory diseases. However, constant use of NSAID may lead to some side effects like gastrointestinal ulcers, bleeding and renal disorders. This study evaluates analgesic and anti-inflammatory activities of Lactobacillus rhamnosus in female Wistar rats.

Diclofenac sodium was used as a standard drug for comparison. L. rhamnosus, drugs and vehicle were administered orally. Acetic acid-induced writhing test and carrageenan-induced paw edema model were used for evaluation. Paw edema and number of writhes were measured subsequently. Pro-inflammatory (interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α and IL-17) and anti-inflammatory (IL-4 and IL-10) cytokines were estimated in serum after 24 h.

Results showed that L. rhamnosus significantly decreased the paw thickness at t=24 h by 28.66 % while drug decreased by 19.33 %. Also, L. rhamnosus treatment and standard drug showed a protection of 66.66 % and 41.66 %, respectively. L. rhamnosus and diclofenac sodium treatment significantly down-regulated pro-inflammatory and up-regulated anti-inflammatory cytokines at p<0.0001. Overall, protection provided by L. rhamnosus was more pronounced in comparison to diclofenac sodium.

The present study clearly suggests that L. rhamnosus suppressed carrageenan-induced paw edema after second phase and decreased the acetic acid-induced writhings. It ameliorated the inflammatory pathways by down-regulating pro-inflammatory cytokines. However, additional clinical investigations are needed to prove the efficacy of L. rhamnosus in treatment/management of inflammatory joint diseases.