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Biomedical subjects

Christopher Fan

Publications and source records attributed to Christopher Fan.

2 recordsLinked to original sources

First-line fecal microbiota transplantation for the management of immune checkpoint inhibitor-mediated diarrhea and colitis.

Immune checkpoint inhibitor (ICI) therapy commonly leads to adverse events such as ICI-mediated diarrhea and colitis (IMDC). Fecal microbiota transplantation (FMT) remains an option for patients with refractory colitis. We report a multi-omics profiling of patients receiving first-line FMT for IMDC. In our preliminary analysis, 10 (76.9%) patients achieve clinical response, with a median time to clinical improvement of 1.5 (1-10.5) days. Among responder patients with baseline and follow-up samples, 6 (75%) show an increase in alpha-diversity post-FMT. Pre-FMT samples show an increase in the abundance scores of plasma cells, neutrophils, macrophages (M1 and M2), memory activated and resting memory CD4+ T cells, CD8+ T cells, T follicular helper (Tfh) cells, and regulatory T cells (Tregs), all of which decrease post-FMT. In a small cohort of patients, we identify potential mechanisms for FMT response and demonstrate that first-line FMT in patients with IMDC (NCT04038619) can be effective.

FMT

Bacteroides ovatus alleviates dysbiotic microbiota-induced graft-versus-host disease.

Acute lower gastrointestinal GVHD (aLGI-GVHD) is a serious complication of allogeneic hematopoietic stem cell transplantation. Although the intestinal microbiota is associated with the incidence of aLGI-GVHD, how the intestinal microbiota impacts treatment responses in aLGI-GVHD has not been thoroughly studied. In a cohort of patients with aLGI-GVHD (n = 37), we found that non-response to standard therapy with corticosteroids was associated with prior treatment with carbapenem antibiotics and a disrupted fecal microbiome characterized by reduced abundances of Bacteroides ovatus. In a murine GVHD model aggravated by carbapenem antibiotics, introducing B. ovatus reduced GVHD severity and improved survival. These beneficial effects of Bacteroides ovatus were linked to its ability to metabolize dietary polysaccharides into monosaccharides, which suppressed the mucus-degrading capabilities of colonic mucus degraders such as Bacteroides thetaiotaomicron and Akkermansia muciniphila, thus reducing GVHD-related mortality. Collectively, these findings reveal the importance of microbiota in aLGI-GVHD and therapeutic potential of B. ovatus.

Graft vs Host Disease