Microbiome and Probiotics: Link to Arthritis

Mohamed K. Bedaiwi; Robert D. Inman

Disclosures

Curr Opin Rheumatol. 2014;26(4):410-415. 

In This Article

Probiotics as a Therapeutic Modulation of the Microbiota

Probiotics are defined as 'live microorganisms which when administered in adequate amounts confer a health benefit on the host'.[40] Evidence suggests that probiotic bacteria modulate both innate and adaptive immunity in the host and may have therapeutic applications of chronic inflammatory diseases. Lactic acid bacteria (LAB) and bifidobacteria are the most known types of bacteria used as probiotics, but certain yeasts and bacilli have also been used.

Probiotics as a modality of treatment will require extensive study to understand their anti-inflammatory effect, long-term efficacy, and the mechanism of action by which they exert their therapeutic role.

Bifidobacterium animalis subspecies lactis IPLA R1 and Bifidobacterium longum IPLA E44 strains have been tested for their safety and their ability to modulate the intestinal microbiota in vivo. The oral administration of B. animalis IPLA R1 and B. longum E44 is considered nontoxic, and has the capacity to modulate the intestinal microbiota of rats by influencing short-chain fatty acids and the bifidobacterial population levels.[41] Oral administration of Lactobacillus casei suppresses the type II collagen-reactive effector function of Th1-type cellular and humoral immune responses.[42] When L. casei was tested in rat collagen-induced arthritis (CIA), arthritis scores and proinflammatory cytokine levels were observed to be lower compared with control rats and with CIA treated with indomethacin.[43] Previous evidence had showed the ability of L. casei to suppress the type II collagen-reactive effector function of Th1-type cellular and humoral immune responses in rat arthritis.[42] HLA-B27 transgenic rats with Bacteroides vulgatus-induced colitis have been treated with antibiotics to prevent and treat colitis, Lactobacillus rhamnosus GG prevented the relapse of colitis with significantly reduced histologic scores.[44]

But there are few studies on the efficacy of probiotics in human arthritis. The effect of L. casei was recently tested in RA patients and showed significantly lower serum proinflammatory cytokines (TNF-α, IL-6, and IL-12) in the probiotic-treated group, with higher level regulatory cytokine (IL-10) as well; clinically, the disease activity score was significantly decreased with L. casei 01 supplementation.[45] Studying the possible mechanisms by which L. casei protects against RA progression showed the effect of oral administration of L. casei to suppress the type II collagen-reactive effector function of Th1-type cellular and humoral immune responses in arthritic inflammation.[42]

One pilot study[46] assessed the effect of probiotics (Lactobacillus acidophilus and Lactobacillus salivarius) in patients with quiescent ulcerative colitis and active SpA, and there was a significant reduction of Bath AS Disease Activity Index and Visual analogue scale score. Despite a theoretical rationale for this therapy in AS patients, another randomized controlled trial of a 12-week course of an oral probiotic in active AS showed no significant benefit over placebo in any of the core outcome domains.[47]

As there are increasingly sophisticated tools for characterizing the gut microbiome, the complex interrelationships between gut flora, immune response, and arthritis will gradually be resolved.

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