COVID-19 VACCINATION RESPONSE IN IMMUNOSUPPRESSED PATIENTS WITH IBD IS ASSOCIATED WITH ALTERED GUT MICROBIOTA FUNCTION

ABSTRACT

Introduction Patients with inflammatory bowel disease (IBD) treated with anti-TNF therapy exhibit attenuated humoral immune responses to vaccination against SARS-CoV-2. The gut microbiota and its functional metabolic output, which are perturbed in IBD, play an important role in shaping host immune responses. We explored whether the gut microbiota and metabolome could explain variation in anti-SARS-CoV-2 vaccination responses in immunosuppressed IBD patients. Methods Faecal and serum samples were prospectively collected from patients with IBD established on infliximab therapy (for >12 weeks) who were undergoing vaccination against SARS-CoV-2. The Roche Elecsys Anti-SARS-CoV-2 spike (S) and nucleocapsid (N) immunoassays were used to measure antibody responses following two doses of either ChAdOx1 nCoV-19 or BNT162b2 vaccine. Seroconversion was defined by a cut-off anti-S concentration of 15 U/ml, which correlated with 20% viral neutralization;anti-S antibody concentration of < 380 U/ml was indicative of poor response to vaccination. Patients with serological evidence of prior SARS-CoV-2 infection were excluded from the analysis. Faecal calprotectin measurement, 16S rRNA gene amplicon sequencing, nuclear magnetic resonance (NMR) spectroscopy and bile acid profiling with ultra-performance liquid chromatography mass spectrometry (UPLC-MS) were performed on faecal samples. Results Forty-five infliximab-treated patients were recruited (median age 40 [range 19-67];32 Crohn's disease, 13 ulcerative colitis;28 with concomitant immunomodulator therapy;six with prior infection). 14 patients (35%) had seroconverted after one dose of vaccine and 37 (95%) seroconverted after two doses. 18 patients (46%) had a poor response after two doses of vaccine. There was no association between faecal calprotectin and vaccine response (p=0.41). No differences between satisfactory and poor vaccine responders were noted in alpha or beta diversity of the gut microbiota. The faecal metabolome of satisfactory responders was enriched in the microbial metabolite trimethylamine (q=0.03). Trends were noted linking the short chain fatty acid butyrate with satisfactory response (P=0.01) and succinate with poor response (P=0.06). No significant differences in primary or secondary bile acids were found to associate with vaccine response. The butyrate-producing genus Roseburia was positively correlated with faecal butyrate abundance (q=0.03). Conclusions Our data suggest an association between gut microbiota function and variable serological response to vaccination against SARS-CoV-2 in immunocompromised patients. Microbial metabolites including trimethylamine and butyrate may be important in mitigating anti-TNF-induced attenuation of the immune response.