Is there any role of renin-angiotensin system inhibitors in modulating inflammatory bowel disease outcome?

Letter: The enigma of angiotensin receptor blocker-associated enteropathy

This article is linked to Schiepatti et al papers. To view these articles, visit https://doi.org/10.1111/apt.17855 and https://doi.org/10.1111/apt.18017.

The Effect of Renin-Angiotensin-Aldosterone System Blocking Agents on the Long-term Disease Course of Patients With Crohn's Disease

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS) has been associated with gastrointestinal inflammation and fibrosis, suggesting that RAAS blockade may be beneficial in patients with inflammatory bowel disease. Using retrospective analysis, we aimed to compare the disease course of patients with Crohn's disease (CD) taking two commonly prescribed classes of RAAS-blocking agents.

STUDY

Patients with CD initiated on an angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) between 2000 and 2016 were enrolled. Data on clinical, radiologic, and procedural surrogate markers of inflammatory bowel disease were collected in the subsequent 3, 5, and 10 years and compared with matched controls using univariate and multivariate analyses.

RESULTS

Compared with controls, patients taking ARBs had fewer instances of corticosteroid use (1.06 vs 2.88, P < 0.01) at 10 years. Patients taking ACEIs had an overall worse disease course, with more imaging studies (3.00 vs 1.75, P = 0.03) and endoscopic procedures (2.70 vs 1.78, P = 0.01) at 5 years, and more imaging studies (6.19 vs 3.50, P < 0.01), endoscopic procedures (5.91 vs 3.78, P < 0.01), and gastrointestinal operations (0.59 vs 0.18, P < 0.02) at 10 years. Results remained significant on multivariate analysis, adjusting for CD characteristics and the use of other antihypertensive medications.

CONCLUSIONS

Our study provides insight into the long-term use of RAAS-blocking agents in patients with CD, suggesting that differences exist among commonly prescribed medication classes. While ACEIs were associated with an overall worse disease course at 5 and 10 years, patients taking ARBs were noted to have fewer instances of corticosteroid use at 10 years. Future large-scale studies are needed to further explore this association.

Heterogeneity in protocols and outcomes to study the effect of renin-angiotensin system blockers in inflammatory bowel disease: A systematic review

BACKGROUND

The renin-angiotensin system (RAS) has been associated with inflammatory bowel disease (IBD), supporting translational relevance of RAS blockers. Comparability of study design/outcomes is fundamental for data analysis/discussion.

OBJECTIVES

We aimed at evaluating the heterogeneity among protocols and outcomes to study the effect of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers in IBD.

METHODS

This study was performed and reported in accordance with the Cochrane recommendations and PRISMA (PROSPERO-CRD42022323853). Systematic searches were performed in PubMed, Scopus and Web of Science. Studies that met the inclusion criteria were selected. Quality assessment of the studies was done with the SYRCLES's risk of bias tools for animal studies.

RESULTS

Thirty-five pre-clinical studies and six clinical studies were included. Chemical induction of colitis was the most used model, but variable doses of the induction agent were reported. All studies reported at least a disease activity index, a macroscopic score, or a histologic assessment, but these scores were methodologically heterogeneous and reported for different characteristics. Great heterogeneity was also found in drug interventions. Inflammatory markers assessed as outcomes were different across studies.

CONCLUSION

Lack of standardization of protocols and outcomes among studies threatens the evidence on how RAS blockers influence IBD outcomes.

What do we know about the renin angiotensin system and inflammatory bowel disease?

INTRODUCTION

The renin-angiotensin system (RAS) is an important homeostatic pathway, with emerging evidence for the impact of its components on inflammation and fibrosis in gastrointestinal tissues. This review aims to review current knowledge of the physiological mechanism of RAS in inflammatory bowel disease (IBD), and potential therapeutic implications.

AREAS COVERED

An extensive online literature review including Pubmed, Medline, and Google Scholar was undertaken. Discussion on the components of the RAS, localization, and physiological functions in the gastrointestinal tract, preclinical, and clinical data in IBD, and the relation with SARS-Cov-2 are covered in this review.

EXPERT OPINION

RAS inhibition may have a role as anti-fibrotic adjunct therapy. Targeting the local gastrointestinal RAS with novel modes of delivery may be a target for future therapeutics for IBD, given the widespread availability and safety of current options as utilized in other diseases. Further insight into the mechanism and downstream effects of gastrointestinal ACE2 may lead to a better understanding of the pathogenesis of IBD.

Exploring the Impact of ACE Inhibition in Immunity and Disease

Angiotensin-converting enzyme (ACE) is a zinc-dependent dipeptidyl carboxypeptidase and is crucial in the renin-angiotensin-aldosterone system (RAAS) but also implicated in immune regulation. Intrinsic ACE has been detected in several immune cell populations, including macrophages and neutrophils, where its overexpression results in enhanced bactericidal and antitumour responses, independent of angiotensin II. With roles in antigen presentation and inflammation, the impact of ACE inhibitors must be explored to understand how ACE inhibition may impact our ability to clear infections or malignancy, particularly in the wake of the coronavirus (SARS-CoV2) pandemic and as antibiotic resistance grows. Patients using ACE inhibitors may be more at risk of postsurgical complications as ACE inhibition in human neutrophils results in decreased ROS and phagocytosis whilst angiotensin receptor blockers (ARBs) have no effect. In contrast, ACE is also elevated in certain autoimmune diseases such as rheumatoid arthritis and lupus, and its inhibition benefits patient outcome where inflammatory immune cells are overactive. Although the ACE autoimmune landscape is changing, some studies have conflicting results and require further input. This review seeks to highlight the need for further research covering ACE inhibitor therapeutics and their potential role in improving autoimmune conditions, cancer, or how they may contribute to immunocompromise during infection and neurodegenerative diseases. Understanding ACE inhibition in immune cells is a developing field that will alter how ACE inhibitors are designed in future and aid in developing therapeutic interventions.

Assessing the impact of blood pressure in the development of inflammatory bowel disease

The purpose of this study is to investigate the potential causal relationships between blood pressure and inflammatory bowel disease (IBD) by using the bidirectional Mendelian randomization (MR) approach. Summary‐level data for blood pressure was extracted from the hitherto largest genome‐wide study (GWAS) with 759 601 participants of European‐descent. We used 56 single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) for blood pressure. Summary statistics for IBD were derived from a GWAS with an overall 59 957 participants of European ancestry, of which 109 IVs were selected. Several robust analytical methods, including inverse‐variance weighted (IVW) method, weighted‐median method, MR‐Egger regression, MR‐PRESSO test, maximum likelihood method, “leave‐one‐out” and multivariable MR analysis were used to evaluate the causal associations between blood pressure and IBD. Genetically predicted higher systolic blood pressure (SBP) was associated with an increased risk of IBD (odds ratio (OR) = 1.05, 95% confidence interval (CI):1.02–1.08, P = .001 by IVW). Subgroup analysis showed that higher SBP was positively associated with Crohn's disease (CD) (OR = 1.06, 95% CI:1.03–1.09, P = 9.18 × 10⁻⁵) and ulcerative colitis (UC) (OR = 1.05, 95% CI:1.01–1.09, P = .017) risk, respectively. In reverse‐direction MR analysis, the authors observed no evidence for the causal effect of IBD on blood pressure. Our findings suggested that high SBP was associated with an increased risk of IBD (for both UC and CD). Further studies are required to clarify the underlying mechanism of this causal association.

Renin-angiotensin system in intestinal inflammation-Angiotensin inhibitors to treat inflammatory bowel diseases?

Inflammatory bowel diseases (IBDs) are chronic disorders of the gastrointestinal tract, which manifest in recurring gastrointestinal inflammation. The current treatment options of IBD are not curative and are lacking in aspects like prevention of fibrosis. New treatment options are needed to fulfil the unmet needs and provide alternatives to drugs with resistances and side effects. Drugs targeting the renin-angiotensin system (RAS), besides being antihypertensive, also possess anti-inflammatory and antifibrotic properties and could offer an inexpensive alternative to control inflammation and fibrosis in the gut. RAS inhibitors have been effective in preventing and alleviating colitis in preclinical studies, but available human data are still sparse. This review outlines the pathophysiological functions of RAS in the gut and summarizes preclinical studies utilizing pharmacological RAS inhibitors in the treatment of experimental colitis. We discuss the alterations in intestinal RAS and the available evidence of the benefits of RAS inhibitors for IBD patients. Retrospective studies comparing IBD patients using ACE inhibitors or angiotensin II receptor blockers have provided optimistic results regarding a milder disease course and fewer hospitalizations and corticosteroid use in patients using RAS inhibitors. Prospective studies are needed to evaluate the effectiveness of these promising medications in the treatment of IBD.

Receptor for advanced glycation end-products axis and coronavirus disease 2019 in inflammatory bowel diseases: A dangerous liaison?

Compelling evidence supports the crucial role of the receptor for advanced glycation end-products (RAGE) axis activation in many clinical entities. Since the beginning of the coronavirus disease 2019 pandemic, there is an increasing concern about the risk and handling of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in inflammatory gastrointestinal disorders, such as inflammatory bowel diseases (IBD). However, clinical data raised during pandemic suggests that IBD patients do not have an increased risk of contracting SARS-CoV-2 infection or develop a more severe course of infection. In the present review, we intend to highlight how two potentially important contributors to the inflammatory response to SARS-CoV-2 infection in IBD patients, the RAGE axis activation as well as the cross-talk with the renin-angiotensin system, are dampened by the high expression of soluble forms of both RAGE and the angiotensin-converting enzyme (ACE) 2. The soluble form of RAGE functions as a decoy for its ligands, and soluble ACE2 seems to be an additionally attenuating contributor to RAGE axis activation, particularly by avoiding the transactivation of the RAGE axis that can be produced by the virus-mediated imbalance of the ACE/angiotensin II/angiotensin II receptor type 1 pathway.