Taxonomic changes in the gut microbiota are associated with cartilage damage independent of adiposity, high fat diet, and joint injury.

Lipodystrophic mice are protected from cartilage damage following joint injury. This protection can be reversed by the implantation of a small adipose tissue graft. The purpose of this study was to evaluate the relationship between the gut microbiota and knee cartilage damage while controlling for adiposity, high fat diet, and joint injury using lipodystrophic (LD) mice. LD and littermate control (WT) mice were fed a high fat diet, chow diet, or were rescued with fat implantation, then challenged with destabilization of the medial meniscus surgery to induce osteoarthritis (OA). 16S rRNA sequencing was conducted on feces. MaAslin2 was used to determine associations between taxonomic relative abundance and OA severity. While serum LPS levels between groups were similar, synovial fluid LPS levels were increased in both limbs of HFD WT mice compared to all groups, except for fat transplanted animals. The Bacteroidetes:Firmicutes ratio of the gut microbiota was significantly reduced in HFD and OA-rescued animals when compared to chow. Nine novel significant associations were found between gut microbiota taxa and OA severity. These findings suggest the presence of causal relationships the gut microbiome and cartilage health, independent of diet or adiposity, providing potential therapeutic targets through manipulation of the microbiome.

[Tropheryma whippelii, an emerging intracellular pathogen causing Whipple disease]. / Tropheryma whippelii, pathogène émergent à culture intracellulaire responsable de la maladie de Whipple.

CLINICAL DIAGNOSIS: Whipple's disease is a diffuse disease with a wide variety of clinical manifestations. Differential diagnoses include chronic enteritis, chronic joint disease, chronic meningoencephalitis and prolonged fever with weight loss, chronic uveitis and endocarditis with negative blood culture. MOLECULAR DIAGNOSIS: Histologically the characteristic lesions contain PAS-positive inclusions. PCR of RNAr gene 16S in fresh tissue identifies Tropheryma whippelii and confirms bacteriological diagnosis. AN EMERGING PATHOGEN: Tropheryma whippelii is a recently identified pathogen highly difficult to culture. Since its discovery, it has been a model of emerging pathogens. Clinical observation, microscope studies, molecular and cellular biology, and bacteriology have all contributed to its recent isolation which should lead to the development of indirect diagnostic techniques [abstract corrected]