Degradation of chondroitin sulfate by the gut microbiota of Chinese individuals

Oral preparations of chondroitin sulfate (CS) have long been used as anti-osteoarthritis (anti-OA) drugs. However, little is known about the degradation of CS by human gut microbiota. In the present study, degradation profiles of CSA (the main constituent of CS drugs) by the human gut microbiota from six healthy subjects were investigated. Each individual’s microbiota had differing degradation activities, but ΔUA-GalNAc4S was the end product in all cases. To elucidate the mechanisms underlying this phenomenon, different CSA-degrading bacteria were isolated from each individual’s microbiota and tested for CSA degradation. In addition to Bacteroides thetaiotaomicron J1, Bacteroides thetaiotaomicron 82 and Bacteroides ovatus E3, a new CSA-degrading bacterium, Clostridium hathewayi R4, was isolated and characterized. Interestingly, at least two different CSA-degrading species were identified from each individual’s gut microbiota. Predictably, these functional bacteria also had differing degradation rates, but still generated the same end product, ΔUA-GalNAc4S. In addition, the human fecal isolates produced different degradation profiles for CSC, CSD, and CSE, suggesting that CS could be readily metabolized to varying extents by diverse microbial consortiums, which may help to explain the poor bioavailability and unequal efficacy of CS among individuals in OA treatment.