Table 1 Summary of studies supporting the contribution of gut microbiota to OA

Collins et al., 2015 [11]

HFS diet-induced obesity rat model

N/A

N/A

Greater Modified Mankin Scores, and higher level of serum LPS in obese animals.

Lactobacillus species and Methanobrevibacter spp. abundance correlated with Mankin scores.

Guss et al., 2019 [12]

Toll-like receptor-5 deficient (TLR5KO) mice, HFD-induced obesity rat model

Tibial cyclic compressive loading

2 weeks or 6 weeks

After 2 weeks of loading, cartilage damage (OARSI score) was not different among groups. After 6 weeks of loading, HFD mice had increased load-induced cartilage damage and elevated serum inflammatory markers. TLR5KO mice is not sufficient to develop severe cartilage damage and treated with chronic antibiotics reduces OA severity. Each group had a distinct gut microbiome composition.

Ulici et al., 2018 [13]

DMM -induced OA mice model

N/A

N/A

Reduced maximum ACS scores in GF mice compared to SPF mice.

Differences in abundance of microbes detected in SPF mice with high or low maximum ACS scores.

Lei et al., 2017 [14]

Patients with symptomatic knee OA (n = 537)

Skimmed milk containing either probiotic LcS or placebo daily

6 months

After 6 months of treatment, WOMAC and VAS scores were significantly decreased in the LcS groups of patients compared to the placebo group. Serum levels of hs-CRP were also significantly lower in patients receiving LcS than placebo.

So et al., 2011 [15]

MIA-induced OA rat model

LcS ± CII/Gln

10 weeks

Oral administration of LcS together with CII and Gln more effectively reduced pain, cartilage destruction, and lymphocyte infiltration than the treatment of Gln or LcS alone.

Sim et al., 2018 [16]

MIA-induced OA rat model

ID-CBT5101 (tyndallized Clostridium butyricum)

6 weeks

ID-CBT5101 treatments effectively preserved the knee cartilage and synovial membrane and significantly decreased the amount of fibrous tissue.

Kwon et al., 2018 [17]

MIA-induced OA rat model

Probiotic complex, rosavin, and zinc

Not indicated

The combination improved OA pain levels by preventing cartilage damage, reduced the expression of proinflammatory cytokines and catabolic factors, and increased the production of anti-inflammatory cytokines as well as the anabolic factor.

Schott et al., 2018 [18]

DMM -induced OA mice model of HFD-induced obesity and in lean mice

Oligofructose (prebiotic)

12 weeks

Prebiotic supplementation reduced OA severity in obese mice. Bifidobacterium pseudolongum abundance increased with prebiotic treatment and its levels were inversely associated with OA severity, systemic, and colon inflammation.

Coulson et al., 2013 [19]

Patients diagnosed with knee OA (n = 38)

GLM extract or GS

12 weeks

Both GLM and GS treatment reduced OA symptoms. In both groups there was a trend toward a decrease in Clostridium and Staphylococcus species and increase in Lactobacillus, Streptococcus and Eubacterium species.

Rios et al., 2019 [20]

HFS diet-induced obesity rat model

Prebiotic fiber supplementation ± HFS diet ± aerobic exercise

12 weeks

Prebiotic fibers, exercise, and the combination of both prevented knee joint damage. The combinative treatments increased the abundance of Bifidobacterium and Roseburia and decreased Clostridium leptum and Akkermansia muciniphila.

Huang et al., 2020 [21]

MLI-induced OA germ-free mice model

FMT (fecal samples collected from human healthy controls, knee OA without metabolic syndrome and knee OA with metabolic syndrome)

10 weeks

OA severity was minimal in GF mice following MLI. Compared with the other groups, transplantation with the knee OA with metabolic syndrome groups, microbiome was associated with higher systemic levels of inflammatory biomarkers, higher gut permeability and worse OA severity. A greater abundance of Fusobacterium and Faecalibaterium and lesser abundance of Ruminococcaceae in transplanted mice were consistently correlated with OA severity and systemic biomarkers concentrations.