Over recent years increasing interest has focussed on the role of the gut microbiome (GM) in the clinical management of osteoarthritis (OA). The bidirectional relationship between the gut and joints, referred to as the gut-joint axis, is a potential therapeutic target for a nutraceutical treatment of OA. The prospect of a novel OA therapy based on dietary manipulation is fascinating, considering that current interventions primarily aim to control pain but do not delay disease progression effectively or restore degraded cartilage. Probiotics are among the most used therapeutics that could modify the gut microbiome. The GM itself, could modulate host g-aminobutyric acid (GABA) levels and influence the host immune system. A manuscript published recently by Amin et al. in the Journal of Traditional and Complementary Medicine, went on to evaluate the protective role of GABA-producing probiotics against pathological OA changes, cartilage loss, and joint inflammation.
Authors used the previously reported GABA-producing probiotic strains, Streptococcus thermophilus (S. thermophilus) and Lactobacillus pentosus (L. pentosus). All in vitro work was carried out using the human chondrocyte cell line, c28/I2. OA was surgically induced by Anterior Cruciate Ligament Transection (ACLT) injury to C57BL mice. To verify and quantify in vivo GABA production by S. thermophilus and L. pentosus, an enzyme immunoassay was carried out on faecal samples, serum samples, and small intestine content of mice.
Findings showed that conditioned media from the probiotics S. thermophilus and L. pentosus, alone or in combination, increased cell proliferation and expression of chondrogenic markers, and also alleviated IL-1b induced changes in the human chondrocyte cell line C28/I2. Following S. thermophilus and L. pentosus bacterial treatment, C57BL mice showed increased GABA level in faeces, small intestine content and serum, compared to control. Moreover, probiotic treatment prevented cartilage damage and decreased inflammatory markers in knee joints of mice subjected to ACLT.
This work was the first to focus on GABA’s chondrogenic and chondroprotective effects on chondrocytes and joints. Given that many probiotic strains are known to produce GABA, including several Lactobacillus and Bifidobacterium strains, authors are expecting that their findings will be used as foundation for further research in the field of gut-joint axis and OA treatment. Authors finally concluded that probiotic/GABA treatment could potentially serve as adjuvant therapy to treat OA.