The gut microbiota and metabolome are associated with diminished COVID-19 vaccine-induced antibody responses in immunosuppressed inflammatory bowel disease patients.

BACKGROUND: 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 infliximab-treated patients with IBD in the CLARITY-IBD study undergoing vaccination against SARS-CoV-2. Antibody responses were measured following two doses of either ChAdOx1 nCoV-19 or BNT162b2 vaccine. Patients were classified as having responses above or below the geometric mean of the wider CLARITY-IBD cohort. 16S rRNA gene amplicon sequencing, nuclear magnetic resonance (NMR) spectroscopy and bile acid profiling with ultra-high-performance liquid chromatography mass spectrometry (UHPLC-MS) were performed on faecal samples. Univariate, multivariable and correlation analyses were performed to determine gut microbial and metabolomic predictors of response to vaccination. FINDINGS: Forty-three infliximab-treated patients with IBD were recruited (30 Crohn's disease, 12 ulcerative colitis, 1 IBD-unclassified; 26 with concomitant thiopurine therapy). Eight patients had evidence of prior SARS-CoV-2 infection. Seventeen patients (39.5%) had a serological response below the geometric mean. Gut microbiota diversity was lower in below average responders (p = 0.037). Bilophila abundance was associated with better serological response, while Streptococcus was associated with poorer response. The faecal metabolome was distinct between above and below average responders (OPLS-DA R2X 0.25, R2Y 0.26, Q2 0.15; CV-ANOVA p = 0.038). Trimethylamine, isobutyrate and omega-muricholic acid were associated with better response, while succinate, phenylalanine, taurolithocholate and taurodeoxycholate were associated with poorer response. INTERPRETATION: Our data suggest that there is an association between the gut microbiota and variable serological response to vaccination against SARS-CoV-2 in immunocompromised patients. Microbial metabolites including trimethylamine may be important in mitigating anti-TNF-induced attenuation of the immune response. FUNDING: JLA is the recipient of an NIHR Academic Clinical Lectureship (CL-2019-21-502), funded by Imperial College London and The Joyce and Norman Freed Charitable Trust. BHM is the recipient of an NIHR Academic Clinical Lectureship (CL-2019-21-002). The Division of Digestive Diseases at Imperial College London receives financial and infrastructure support from the NIHR Imperial Biomedical Research Centre (BRC) based at Imperial College Healthcare NHS Trust and Imperial College London. Metabolomics studies were performed at the MRC-NIHR National Phenome Centre at Imperial College London; this work was supported by the Medical Research Council (MRC), the National Institute of Health Research (NIHR) (grant number MC_PC_12025) and infrastructure support was provided by the NIHR Imperial Biomedical Research Centre (BRC). The NIHR Exeter Clinical Research Facility is a partnership between the University of Exeter Medical School College of Medicine and Health, and Royal Devon and Exeter NHS Foundation Trust. This project is supported by the National Institute for Health Research (NIHR) Exeter Clinical Research Facility. The views expressed are those of the authors and not necessarily those of the NIHR or the UK Department of Health and Social Care.

How to adapt an intestinal microbiota transplantation programme to reduce the risk of invasive multidrug-resistant infection.

BACKGROUND: Vulnerable patients with intestinal colonization of multidrug-resistant organisms (MDROs) are recognized to be at increased risk of invasive MDRO-driven infection. Intestinal microbiota transplantation (IMT, also called faecal microbiota transplant) is the transfer of healthy screened donor stool to an affected recipient, and recent interest has focused on its impact on the reduction of invasive MDRO infection. OBJECTIVES: To describe how to establish a clinical IMT pathway for patients at risk of MDRO invasive infection, with special considerations for optimizing administration and assessment of endpoints. SOURCES: Expert guidelines and peer-reviewed clinical studies are encompassed and discussed. CONTENT: IMT is offered to patients with MDROs detected on rectal or stool screening and either at risk of MDRO invasive infection due to altered immune status or those with recurrent MDRO-mediated invasive disease and considered at risk of further disease. Donor screening should include pathogens with theoretical or demonstrated risk of transmission (including MDROs themselves and SARS-CoV-2) and take into consideration the relative immunosuppressed state of potential recipients. Delivery of IMT is timed for when the patient is free from active infection, but no additional antibiotics are indicated. If administered when future immunosuppression is to take place, IMT is aligned at least 2 weeks beforehand to ensure sufficient time for engraftment. Patients are followed up in terms of adverse effects from IMT and clinicians are advised to discuss with the IMT multidisciplinary team on choice of antibiotics if needed to take into consideration the impact upon the intestinal microbiome. Prevention of invasive disease is the primary measure of success, rather than using intestinal decolonization as a binary outcome. Repeat IMT is considered case by case. IMPLICATIONS: Future research areas should include randomized studies that consider clinical outcomes and cost-effectiveness, and better understanding of mechanisms to identify markers of treatment success and functional microbiome components that could be used therapeutically.

Probiotics reduce self-reported symptoms of upper respiratory tract infection in overweight and obese adults: should we be considering probiotics during viral pandemics?

Gut microbiome manipulation to alter the gut-lung axis may potentially protect humans against respiratory infections, and clinical trials of probiotics show promise in this regard in healthy adults and children. However, comparable studies are lacking in overweight/obese people, who have increased risks in particular of viral upper respiratory tract infections (URTI). This Addendum further analyses our recent placebo-controlled trial of probiotics in overweight/obese people (focused initially on weight loss) to investigate the impact of probiotics upon the occurrence of URTI symptoms. As well as undergoing loss of weight and improvement in certain metabolic parameters, study participants taking probiotics experienced a 27% reduction in URTI symptoms versus control, with those ≥45 years or BMI ≥30 kg/m2 experiencing greater reductions. This symptom reduction is apparent within 2 weeks of probiotic use. Gut microbiome diversity remained stable throughout the study in probiotic-treated participants. Our data provide support for further trials to assess the potential role of probiotics in preventing viral URTI (and possibly also COVID-19), particularly in overweight/obese people.

The gut microbiome: an under-recognised contributor to the COVID-19 pandemic?

The novel coronavirus infection (COVID-19) caused by the SARS-CoV-2 virus has spread rapidly across the globe, culminating in major global morbidity and mortality. As such, there has been a rapid escalation in scientific and clinical activity aimed at increasing our comprehension of this virus. This volume of work has led to early insights into risk factors associated with severity of disease, and mechanisms that underpin the virulence and dynamics involved in viral transmission. These insights ultimately may help guide potential therapeutics to reduce the human, economic and social impact of this pandemic. Importantly, the gastrointestinal (GI) tract has emerged as an important organ influencing propensity to, and potentially severity of, COVID-19 infection. Furthermore, the gut microbiome has been linked to a variety of risk factors for COVID-19 infection, and manipulation of the gut microbiome is an attractive potential therapeutic target for a number of diseases. While data profiling the gut microbiome in COVID-19 infection to date are limited, they support the possibility of several routes of interaction between COVID-19, the gut microbiome, angiotensin converting enzyme 2 (ACE-2) expression in the small bowel and colon and gut inflammation. This article will explore the evidence that implicates the gut microbiome as a contributing factor to the pathogenesis, severity and disease course of COVID-19, and speculate about the gut microbiome's capability as a therapeutic avenue against COVID-19. LAY SUMMARY: It has been noted that certain baseline gut profiles of COVID-19 patients are associated with a more severe disease course, and the gut microbiome impacts the disease course of several contributory risk factors to the severity of COVID-19. A protein called ACE-2, which is found in the small intestine among other sites, is a key receptor for COVID-19 virus entry; there is evidence that the gut microbiome influences ACE-2 receptor expression, and hence may play a role in influencing COVID-19 infectivity and disease severity. Furthermore, the gut microbiome plays a significant role in immune regulation, and hence may be pivotal in influencing the immune response to COVID-19. In terms of understanding COVID-19 treatments, the gut microbiome is known to interact with several drug classes being used to target COVID-19 and should be factored into our understanding of how patients respond to treatment. Importantly, our understanding of the role of the gut microbiome in COVID-19 infection remains in its infancy, but future research may potentially aid our mechanistic understanding of viral infection, and new ways in which we might approach treating it.