Gut-associated lymphoid tissue attrition associates with response to anti-α4β7 therapy in ulcerative colitis

Targeting the α4β7-MAdCAM-1 axis with vedolizumab (VDZ) is a front-line therapeutic paradigm in ulcerative colitis (UC). However, mechanism(s) of action (MOA) of VDZ remain relatively undefined. Here, we examined three distinct cohorts of patients with UC (n=83, n=60, and n=21), to determine the effect of VDZ on the mucosal and peripheral immune system. Transcriptomic studies with protein level validation were used to study drug MOA using conventional and transgenic murine models. We found a significant decrease in colonic and ileal naïve B and T cells and circulating gut-homing plasmablasts (β7+) in VDZ-treated patients, pointing to gut-associated lymphoid tissue (GALT) targeting by VDZ. Murine Peyer's patches (PP) demonstrated a significant loss cellularity associated with reduction in follicular B cells, including a unique population of epithelium-associated B cells, following anti-α4β7 antibody (mAb) administration. Photoconvertible (KikGR) mice unequivocally demonstrated impaired cellular entry into PPs in anti-α4β7 mAb treated mice. In VDZ-treated, but not anti-tumor necrosis factor-treated UC patients, lymphoid aggregate size was significantly reduced in treatment responders compared to non-responders, with an independent validation cohort further confirming these data. GALT targeting represents a novel MOA of α4β7-targeted therapies, with major implications for this therapeutic paradigm in UC, and for the development of new therapeutic strategies.

Intestinal Inflammation Modulates the Expression of ACE2 and TMPRSS2 and Potentially Overlaps With the Pathogenesis of SARS-CoV-2-related Disease

BACKGROUND AND AIMS

The presence of gastrointestinal symptoms and high levels of viral RNA in the stool suggest active severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication within enterocytes.

METHODS

Here, in multiple, large cohorts of patients with inflammatory bowel disease (IBD), we have studied the intersections between Coronavirus Disease 2019 (COVID-19), intestinal inflammation, and IBD treatment.

RESULTS

A striking expression of ACE2 on the small bowel enterocyte brush border supports intestinal infectivity by SARS-CoV-2. Commonly used IBD medications, both biologic and nonbiologic, do not significantly impact ACE2 and TMPRSS2 receptor expression in the uninflamed intestines. In addition, we have defined molecular responses to COVID-19 infection that are also enriched in IBD, pointing to shared molecular networks between COVID-19 and IBD.

CONCLUSIONS

These data generate a novel appreciation of the confluence of COVID-19- and IBD-associated inflammation and provide mechanistic insights supporting further investigation of specific IBD drugs in the treatment of COVID-19. Preprint doi: https://doi.org/10.1101/2020.05.21.109124.

Hepatocellular Carcinoma in Hispanic Patients: Trends and Outcomes in a Large United States Cohort

Hepatocellular carcinoma (HCC) has a strong racial and ethnic association, with Hispanic patients having a higher incidence and mortality. However, there are limited data regarding clinical features and outcomes. This study includes Hispanic and non‐Hispanic White patients with HCC diagnosed between January 2000 and June 2014 from five United States academic medical centers. The chi‐square test for categorical variables and analysis of variance for continuous variables were used for statistical analysis, with two‐tailed P < 0.05 considered statistically significant. Of 5,327 patients, 4,217 met inclusion criteria, of whom 12.3% were Hispanic patients. Compared to their non‐Hispanic White counterparts, Hispanic patients were older at age of diagnosis (mean ± SD, 64.2 ± 10.9 vs. 61.9 ± 10.5 years; P < 0.0001), with higher body mass index (29.6 ± 6.5 vs. 28.8 ± 5.9 kg/m²; P = 0.01), and were more likely to have diabetes and hypertension. Hispanic patients had significantly more nonalcoholic fatty liver disease and alcohol‐related liver disease (both P < 0.0001). Hispanic patients presented with larger tumors, more advanced stage disease, and increased rates of macrovascular invasion and extrahepatic spread. HCCs in Hispanic patients were less likely to be within Milan criteria (26% vs. 38%; P < 0.0001) and were less likely to be treated with resection (9% vs. 13%; P = 0.03) or transplantation (8% vs. 19%; P < 0.0001). Hispanic patients had a median overall survival of 1.4 years (95% confidence interval [CI], 1.22‐1.56), which was similar to that of non‐Hispanic White patients (1.3 years; 95% CI, 1.26‐1.41; P = 0.07). Conclusion: Hispanic patients with HCC were more likely to have metabolic risk factors for chronic liver disease, including obesity. Despite diagnosis at more advanced stages with less curative intervention than non‐Hispanic White patients, median overall survival was similar between groups.

Antibiotic-induced acceleration of type 1 diabetes alters maturation of innate intestinal immunity

The early-life intestinal microbiota plays a key role in shaping host immune system development. We found that a single early-life antibiotic course (1PAT) accelerated type 1 diabetes (T1D) development in male NOD mice. The single course had deep and persistent effects on the intestinal microbiome, leading to altered cecal, hepatic, and serum metabolites. The exposure elicited sex-specific effects on chromatin states in the ileum and liver and perturbed ileal gene expression, altering normal maturational patterns. The global signature changes included specific genes controlling both innate and adaptive immunity. Microbiome analysis revealed four taxa each that potentially protect against or accelerate T1D onset, that were linked in a network model to specific differences in ileal gene expression. This simplified animal model reveals multiple potential pathways to understand pathogenesis by which early-life gut microbiome perturbations alter a global suite of intestinal responses, contributing to the accelerated and enhanced T1D development.

Gastric Helicobacter pylori Infection Affects Local and Distant Microbial Populations and Host Responses

Helicobacter pylori is a late-in-life human pathogen with potential early-life benefits. Although H. pylori is disappearing from the human population, little is known about the influence of H. pylori on the host's microbiota and immunity. Studying the interactions of H. pylori with murine hosts over 6 months, we found stable colonization accompanied by gastric histologic and antibody responses. Analysis of gastric and pulmonary tissues revealed increased expression of multiple immune response genes, conserved across mice and over time in the stomach and more transiently in the lungs. Moreover, H. pylori infection led to significantly different population structures in both the gastric and intestinal microbiota. These studies indicate that H. pylori influences the microbiota and host immune responses not only locally in the stomach, but distantly as well, affecting important target organs.

Understanding the effect of early-life pulsed antibiotic treatment on mucosal T-lymphocyte populations (MUC4P.827)

Broad-spectrum antibiotics are frequently prescribed for children. The gut microbiota have functional roles in the development and differentiation of the host immune system. Early-life antibiotic use may have dynamic effects on the host microbiota, promoting long-term immunologic dysregulation and subsequent allergic and autoimmune pathology. Using a model of early-life antibiotic use, we hypothesize that early-life pulsed antibiotic treatment (PAT) -induced perturbation of the intestinal microbiota leads to alterations in tissue-specific and systemic T-cell populations. To test this hypothesis, we characterized splenic and ileal T-cell populations in control and PAT-treated C57BL/6 mice. Flow cytometric analysis demonstrated that early-life PAT significantly (p&lt;0.05) decreased the frequency of splenic CD4+ and CD8+ T-cells and ileal CD4+ IL-17A+ Th17 populations. In contrast, ileal CD4+ Tbet+ (Th1) T cells and CD4+ Foxp3+ regulatory T-cell populations were significantly increased in PAT-treated mice. Alterations in immune cell populations were associated with microbial compositional changes, including significantly higher relative abundance of Enterobacteriaceae and Akkermansia muciniphila in PAT-treated mice. These results provide evidence that early-life perturbation of the intestinal microbiota by PAT modulates systemic and mucosal T-cell populations, phenotypes that may persist after microbial recovery, promoting life-long consequences to host immunity.

EZH2 couples pancreatic regeneration to neoplastic progression

Although the polycomb group protein Enhancer of Zeste Homolog 2 (EZH2) is well recognized for its role as a key regulator of cell differentiation, its involvement in tissue regeneration is largely unknown. Here we show that EZH2 is up-regulated following cerulein-induced pancreatic injury and is required for tissue repair by promoting the regenerative proliferation of progenitor cells. Loss of EZH2 results in impaired pancreatic regeneration and accelerates KRas(G12D)-driven neoplasia. Our findings implicate EZH2 in constraining neoplastic progression through homeostatic mechanisms that control pancreatic regeneration and provide insights into the documented link between chronic pancreatic injury and an increased risk for pancreatic cancer.