BackgroundShort-chain fatty acids derived from gut microbial fermentation of dietary fiber have been shown to suppress autoimmunity through mechanisms that include enhanced regulation by T regulatory cells (Tregs).MethodsUsing a murine kidney transplantation model, we examined the effects on alloimmunity of a high-fiber diet or supplementation with the short-chain fatty acid acetate. Kidney transplants were performed from BALB/c(H2d) to B6(H2b) mice as allografts in wild-type and recipient mice lacking the G protein–coupled receptor GPR43 (the metabolite-sensing receptor of acetate). Allograft mice received normal chow, a high-fiber diet, or normal chow supplemented with sodium acetate. We assessed rejection at days 14 (acute) and 100 (chronic), and used 16S rRNA sequencing to determine gut microbiota composition pretransplantation and post-transplantation.ResultsWild-type mice fed normal chow exhibited dysbiosis after receiving a kidney allograft but not an isograft, despite the avoidance of antibiotics and immunosuppression for the latter. A high-fiber diet prevented dysbiosis in allograft recipients, who demonstrated prolonged survival and reduced evidence of rejection compared with mice fed normal chow. Allograft mice receiving supplemental sodium acetate exhibited similar protection from rejection, and subsequently demonstrated donor-specific tolerance. Depletion of CD25+ Tregs or absence of the short-chain fatty acid receptor GPR43 abolished this survival advantage.ConclusionsManipulation of the microbiome by a high-fiber diet or supplementation with sodium acetate modified alloimmunity in a kidney transplant model, generating tolerance dependent on Tregs and GPR43. Diet-based therapy to induce changes in the gut microbiome can alter systemic alloimmunity in mice, in part through the production of short-chain fatty acids leading to Treg cell development, and merits study as a potential clinical strategy to facilitate transplant acceptance.

Background: Strongyloidiasis is caused by the helminth Strongyloides stercoralis and is well-recognised amongst transplant recipients. Serious complications, including Strongyloides hyperinfection which is a syndrome of accelerated autoinfection, or disseminated disease, can occur post-transplantation, resulting in significant morbidity and mortality. Here we present the first published case we are aware of, describing post-transplant Strongyloides hyperinfection in an HIV-positive kidney transplant patient. We discuss the diagnostic challenges and the role of pre-transplant screening. Case presentation: A 58-year-old African-American male, originally from the Caribbean, received a deceased donor kidney transplant for presumed focal segmental glomerulosclerosis. He was known to be HIV-positive, with a stable CD4 count, and an undetectable viral load. Five months post-transplant, he developed gastrointestinal symptoms and weight loss. He had a normal eosinophil count (0.1-0.2 × 109/L), negative serum cytomegalovirus DNA, and negative blood and stool cultures. His Strongyloides serology remained negative throughout. A diagnosis of Strongyloides hyperinfection was made by the histological examination of his duodenum and lung, which identified the parasites. He completed his course of treatment with Ivermectin but exhibited profound deconditioning and required a period of total parenteral nutrition. He was subsequently discharged after a prolonged hospital admission of 54 days. Conclusions: This case highlights the challenges in diagnosing Strongyloides infection and the need to maintain a high index of clinical suspicion. Non-invasive techniques for the diagnosis of Strongyloides may be insufficient. Routine pre-transplant serological strongyloidiasis screening is now performed at our centre.

No abstract

No abstract