Identifying overweight patients at risk of osteoarthritis based on their gut microbiota

Because of the overload imposed on their joints, overweight people are more prone to osteoarthritis. But how to identify those most at risk? The answer could lie in the gut microbiota which is involved in many inflammatory diseases, including osteoarthritis.

Lower microbial diversity in the gut of overweight patients with osteoarthritis

A prospective study was conducted in China on overweight people (25<BMI (sidenote: Body Mass Index.  Ratio of weight in kg to square of height in sq.m ) <30): 182 stool samples from 86 overweight patients with osteoarthritis (25 men and 61 women aged 50 to 72) and 96 overweight volunteers without osteoarthritis (40 men and 56 women aged 50 to 76) were sequenced (16S ribosomal RNA) to characterize their microbial composition. The study found a lower diversity and abundance in the gut microbiota of these overweight subjects in case of osteoarthritis, something that could indicate a disease-associated dysbiosis, according to the authors. The presence of 9 phyla was significantly different (higher or lower content, depending on the phylum) in case of osteoarthritis: for instance, the content of Firmicutes and Bacteroidetes, whose ratio is used as an indicator of dysbiosis, was significantly higher in patients with osteoarthritis. Moreover, 87 bacterial genera were different between overweight patients with and without osteoarthritis. All these bacteria allowed researchers to identify relevant osteoarthritis biomarkers.

Predicting the risk of osteoarthritis based on 7 biomarkers

Based on the previous results, the researchers identified 7 biomarkers found in the gut microbiota that could be used to develop a non-invasive tool for early assessment of the risk of osteoarthritis in overweight people: 3 over-represented bacterial genera in patients with osteoarthritis (Gemmiger, Klebsiella and Akkermansia) and 4 that are under-represented in those same patients (Bacteroides, Prevotella, Alistipes and Parabacteroides). Taken together, these biomarkers are able to precisely predict the risk of osteoarthritis (area under the curve of 83.36%). Among them the Bacteroides genus seems to play such a predominant role that the authors are considering it as a possible target for osteoarthritis treatment.