Upregulation of circulating components of the alternative renin-angiotensin system in inflammatory bowel disease: A pilot study

Angiotensin-converting enzymes 1 and 2 in the feces: presence and catalytic activity in the rat 2,4,6-trinitrobenzene sulfonic acid-induced model of colitis

BACKGROUND AND AIM

Inflammatory bowel disease is challenging to diagnose. Fecal biomarkers offer noninvasive solutions. The renin-angiotensin-aldosterone system is implicated in intestinal inflammation. Angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) regulate its activity, but conflicting findings on these enzymes in colitis require further investigation. We aimed to assess ACE and ACE2 presence and activities in the feces, serum, and colon of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rats.

METHODS

Colitis was induced in male rats by rectal instillation of a 21% ethanolic TNBS solution. After rats' sacrifice, colonic portions, serum, and feces were collected. ACE and ACE2 presence in the feces was analyzed by western Blot, and colonic and serum enzymes' concentrations were quantified using ELISA kits. ACE activity was assessed using Hippuryl-His-Leu and Z-Phe-His-Leu as substrates. ACE2 activity was assessed using Mca-APK (Dnp) as a substrate in the presence and absence of DX600 (ACE2 inhibitor).

RESULTS

An ACE isoform of ~70 kDa was found only in the feces of TNBS-induced rats. ACE concentration was higher than that of ACE2 in the serum and the inflamed colon. ACE N-domain activity was higher than that of the C-domain in all matrices. ACE2 activity was higher in the feces of TNBS-induced animals compared to controls.

CONCLUSION

A 70 kDa ACE isoform only detected in the feces of TNBS-induced rats may have translational relevance. ACE N-domain seems to play a significant role in regulating colonic lesions. Further research using human samples is necessary to validate these findings.

Abnormal platelet parameters in inflammatory bowel disease: a systematic review and meta-analysis

BACKGROUND

Platelet dysfunction plays a critical role in the pathogenesis of inflammatory bowel disease (IBD). Despite clinical observations indicating abnormalities in platelet parameters among IBD patients, inconsistencies persist, and these parameters lack standardization for diagnosis or clinical assessment.

METHODS

A comprehensive search was conducted in the PubMed, Embase, Web of Science, and Cochrane Library databases for relevant articles published up to December 16th, 2023. A random-effects model was employed to pool the weighted mean difference (WMD) and 95% confidence interval (95% CI) of platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW), and plateletcrit (PCT) between IBD patients and healthy controls, and subgroup analyses were performed.

RESULTS

The meta-analysis included 79 articles with 8,350 IBD patients and 13,181 healthy individuals. The results revealed significantly increased PLT and PCT levels (WMD: 69.910, 95% CI: 62.177, 77.643 109/L; WMD: 0.046%, 95% CI: 0.031%, 0.061%), and decreased MPV levels (WMD: -0.912, 95% CI: -1.086, -0.739 fL) in IBD patients compared to healthy individuals. No significant difference was found in PDW between the IBD and control groups (WMD: -0.207%, 95% CI: -0.655%, 0.241%). Subgroup analysis by disease type and disease activity showed no change in the differences for PLT, PCT, and MPV in the ulcerative colitis and Crohn's disease groups, as well as the active and inactive groups. Notably, the active group exhibited significantly lower PDW levels than the control group (WMD: -1.138%, 95% CI: -1.535%, -0.741%).

CONCLUSIONS

Compared with healthy individuals, IBD patients display significantly higher PLT and PCT and significantly lower MPV. Monitoring the clinical manifestations of platelet abnormalities serves as a valuable means to obtain diagnostic and prognostic information. Conversely, proactive measures should be taken to prevent the consequences of platelet abnormalities in individuals with IBD.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023493848.

High prevalence of SARS-Coronavirus-2 in patients with inflammatory bowel disease and the role of soluble angiotensin converting Enzyme2

Context: Patients with inflammatory bowel disease (IBD) were found to have the higher intestinal expression of Angiotensin-Converting Enzyme2 (ACE2) that could consequently increase susceptibility to COVID-19 infection.Objective: This study reports the outcomes of COVID-19 infection in a large cohort of IBD patients. We compare levels of serum ACE and IFN-α between COVID19 patients with and without IBD. We performed a cross-sectional retrospective multicenter study.Methods: We enrolled patients with IBD screened for SARS-COV-2 in six medical centres in Iran from June to November 2020. The blood samples were drawn to measure COVID-19 IgM and IgG, and serum levels of sACE2, sACE1, and interferon-α, regardless of suspicious symptoms have done the molecular test.Results: A total of 534 IBD patients were included in the study. Of these, 109 (20.0%) cases had detectable IgG and IgM against SARS-CoV-2. sACE2 levels were higher in IBD patients than controls, whereas ACE1and IFN-α levels were similar among groups.

Ace Deficiency Induces Intestinal Inflammation in Zebrafish

Inflammatory bowel disease (IBD) is a nonspecific chronic inflammatory disease resulting from an immune disorder in the intestine that is prone to relapse and incurable. The understanding of the pathogenesis of IBD remains unclear. In this study, we found that ace (angiotensin-converting enzyme), expressed abundantly in the intestine, plays an important role in IBD. The deletion of ace in zebrafish caused intestinal inflammation with increased expression of the inflammatory marker genes interleukin 1 beta (il1b), matrix metallopeptidase 9 (mmp9), myeloid-specific peroxidase (mpx), leukocyte cell-derived chemotaxin-2-like (lect2l), and chemokine (C-X-C motif) ligand 8b (cxcl8b). Moreover, the secretion of mucus in the ace-/- mutants was significantly higher than that in the wild-type zebrafish, validating the phenotype of intestinal inflammation. This was further confirmed by the IBD model constructed using dextran sodium sulfate (DSS), in which the mutant zebrafish had a higher susceptibility to enteritis. Our study reveals the role of ace in intestinal homeostasis, providing a new target for potential therapeutic interventions.

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.

COVID-19 and Gastrointestinal Tract: From Pathophysiology to Clinical Manifestations

Background: Since its first report in Wuhan, China, in December 2019, COVID-19 has become a pandemic, affecting millions of people worldwide. Although the virus primarily affects the respiratory tract, gastrointestinal symptoms are also common. The aim of this narrative review is to provide an overview of the pathophysiology and clinical manifestations of gastrointestinal COVID-19. Methods: We conducted a systematic electronic search of English literature up to January 2023 using Medline, Scopus, and the Cochrane Library, focusing on papers that analyzed the role of SARS-CoV-2 in the gastrointestinal tract. Results: Our review highlights that SARS-CoV-2 directly infects the gastrointestinal tract and can cause symptoms such as diarrhea, nausea/vomiting, abdominal pain, anorexia, loss of taste, and increased liver enzymes. These symptoms result from mucosal barrier damage, inflammation, and changes in the microbiota composition. The exact mechanism of how the virus overcomes the acid gastric environment and leads to the intestinal damage is still being studied. Conclusions: Although vaccination has increased the prevalence of less severe symptoms, the long-term interaction with SARS-CoV-2 remains a concern. Understanding the interplay between SARS-CoV-2 and the gastrointestinal tract is essential for future management of the virus.

Dysregulation of intestinal epithelial electrolyte transport in canine chronic inflammatory enteropathy and the role of the renin-angiotensin-aldosterone-system

Chronic diarrhea is a hallmark sign of canine chronic inflammatory enteropathy (CIE), leading to fluid and electrolyte losses. Electrolyte homeostasis is regulated by the renin-angiotensin-aldosterone-system (RAAS), which might be involved in (counter-)regulating electrolyte losses in canine CIE. Whether and which electrolyte transporters are affected or if RAAS is activated in canine CIE is unknown. Thus, intestinal electrolyte transporters and components of the RAAS were investigated in dogs with CIE. Serum RAAS fingerprint analysis by mass spectrometry was performed in 5 CIE dogs and 5 healthy controls, and mRNA levels of intestinal electrolyte transporters and local RAAS pathway components were quantified by RT-qPCR in tissue biopsies from the ileum (7 CIE, 10 controls) and colon (6 CIE, 12 controls). Concentrations of RAAS components and mRNA expression of electrolyte transporters were compared between both groups of dogs and were tested for associations among each other. In dogs with CIE, associations with clinical variables were also tested. Components of traditional and alternative RAAS pathways were higher in dogs with CIE than in healthy controls, with statistical significance for Ang I, Ang II, and Ang 1-7 (all p < 0.05). Expression of ileal, but not colonic electrolyte transporters, such as Na+/K+-ATPase, Na+/H+-exchanger 3, Cl- channel 2, down-regulated in adenoma, and Na+-glucose-cotransporter (all p < 0.05) was increased in CIE. Our results suggest that the dys- or counter-regulation of intestinal electrolyte transporters in canine CIE might be associated with a local influence of RAAS. Activating colonic absorptive reserve capacities may be a promising therapeutic target in canine CIE.

Time to eRAASe chronic inflammation: current advances and future perspectives on renin-angiotensin-aldosterone-system and chronic intestinal inflammation in dogs and humans

Chronic idiopathic intestinal inflammation is an increasing worldwide problem that affects companion animals, especially dogs, and human patients. Although these disease entities have been intensely investigated recently, many questions remain, and alternative therapeutic options are needed. Diarrhea caused by dysregulation of intestinal electrolyte transport and subsequent fluid and electrolyte losses often leads to secondary consequences for the patient. Currently, it is not exactly clear which mechanisms are involved in the dysregulation of intestinal fluid absorption, but differences in intestinal electrolyte shifts between human and canine patients suggest species-specific regulatory or counterregulatory mechanisms. Several intestinal electrolyte transporters are differentially expressed in human patients with inflammatory bowel disease (IBD), whereas there are virtually no studies on electrolyte transporters and their endocrine regulation in canine chronic inflammatory enteropathy. An important mechanism involved in regulating fluid and electrolyte homeostasis is the renin-angiotensin-aldosterone-system (RAAS), which may affect intestinal Na⁺ transport. While RAAS has previously been considered a systemic regulator of blood pressure, additional complex roles of RAAS in inflammatory processes have been unraveled. These alternative RAAS pathways may pose attractive therapeutic targets to address diarrhea and, thus, electrolyte shifts in human IBD and canine chronic inflammatory enteropathy. This article comparatively summarizes the current knowledge about electrolyte transport in human IBD and canine chronic inflammatory enteropathy and the role of RAAS and offers perspectives for novel therapeutic avenues.

Gastrointestinal Manifestations of SARS-CoV-2: Transmission, Pathogenesis, Immunomodulation, Microflora Dysbiosis, and Clinical Implications

The clinical manifestation of COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in the respiratory system of humans is widely recognized. There is increasing evidence suggesting that SARS-CoV-2 possesses the capability to invade the gastrointestinal (GI) system, leading to the manifestation of symptoms such as vomiting, diarrhea, abdominal pain, and GI lesions. These symptoms subsequently contribute to the development of gastroenteritis and inflammatory bowel disease (IBD). Nevertheless, the pathophysiological mechanisms linking these GI symptoms to SARS-CoV-2 infection remain unelucidated. During infection, SARS-CoV-2 binds to angiotensin-converting enzyme 2 and other host proteases in the GI tract during the infection, possibly causing GI symptoms by damaging the intestinal barrier and stimulating inflammatory factor production, respectively. The symptoms of COVID-19-induced GI infection and IBD include intestinal inflammation, mucosal hyperpermeability, bacterial overgrowth, dysbiosis, and changes in blood and fecal metabolomics. Deciphering the pathogenesis of COVID-19 and understanding its exacerbation may provide insights into disease prognosis and pave the way for the discovery of potential novel targets for disease prevention or treatment. Besides the usual transmission routes, SARS-CoV-2 can also be transmitted via the feces of an infected person. Hence, it is crucial to implement preventive and control measures in order to mitigate the fecal-to-oral transmission of SARS-CoV-2. Within this context, the identification and diagnosis of GI tract symptoms during these infections assume significance as they facilitate early detection of the disease and the development of targeted therapeutics. The present review discusses the receptors, pathogenesis, and transmission of SARS-CoV-2, with a particular focus on the induction of gut immune responses, the influence of gut microbes, and potential therapeutic targets against COVID-19-induced GI infection and IBD.

Azelaic Acid Regulates the Renin-Angiotensin System and Improves Colitis Based on Network Pharmacology and Experimentation

Inflammatory bowel disease (IBD), which encompasses Crohn's disease and ulcerative colitis, has a complicated etiology that might be brought on by metabolic dysbiosis. Previous metabonomic studies have found a correlation between decreased azelaic acid (AzA) and IBD. Herein, data from the Metabolomics Workbench showed that the content of AzA decreased in IBD patients (PR000639) and dextran sulfate sodium (DSS)-induced mice (PR000837). The effects of AzA on IBD were then examined using a DSS-induced mouse model, and the results demonstrated that AzA alleviated clinical activity, decreased pro-inflammatory cytokine production, and reduced CD4⁺CD25⁺Foxp3⁺Treg percentages in mesenteric lymph nodes. Through network pharmacology analysis, we discovered 99 candidate IBD-associated genes that are potentially regulated by AzA. After the enrichment analysis of the candidate genes, the renin-angiotensin system (RAS) pathway was one of the most substantially enriched pathways. Additionally, AzA reversed the increased expression of important RAS components (ACE, ACE2, and MAS1L) following DSS induction, suggesting that AzA exerts therapeutic effects possibly via the RAS pathway. This study suggests that AzA may be a promising drug for treating IBD.

COVID-19 susceptibility and clinical outcomes in inflammatory bowel disease: An updated systematic review and meta-analysis

The susceptibility, risk factors, and prognosis of COVID-19 in patients with inflammatory bowel disease (IBD) remain unknown. Thus, our study aims to assess the prevalence and clinical outcomes of COVID-19 in IBD. We searched PubMed, EMBASE, and medRxiv from 2019 to 1 June 2022 for cohort and case-control studies comparing the prevalence and clinical outcomes of COVID-19 in patients with IBD and in the general population. We also compared the outcomes of patients receiving and not receiving 5-aminosalicylates (ASA), tumour necrosis factor antagonists, biologics, systemic corticosteroids, or immunomodulators for IBD. Thirty five studies were eligible for our analysis. Pooled odds ratio of COVID-19-related hospitalisation, intensive care unit (ICU) admission, or death in IBD compared to in non-IBD were 0.58 (95% confidence interval (CI) = 0.28-1.18), 1.09 (95% CI = 0.27-4.47), and 0.67 (95% CI = 0.32-1.42), respectively. Inflammatory bowel disease was not associated with increased hospitalisation, ICU admission, or death. Susceptibility to COVID-19 did not increase with any drugs for IBD. Hospitalisation, ICU admission, and death were more likely with 5-ASA and corticosteroid use. COVID-19-related hospitalisation (Odds Ratio (OR): 0.53; 95% CI = 0.38-0.74) and death (OR: 0.13; 95% CI = 0.13-0.70) were less likely with Crohn's disease than ulcerative colitis (UC). In conclusion, IBD does not increase the mortality and morbidity of COVID-19. However, physicians should be aware that additional monitoring is needed in UC patients or in patients taking 5-ASA or systemic corticosteroids.

Landscape of new drugs and targets in inflammatory bowel disease

Although the therapeutic armamentarium of Inflammatory bowel diseases (IBD) physicians has expanded rapidly in recent years, a proportion of patients remain with a suboptimal response to medical treatment due to primary no response, loss of response or intolerance to currently available drugs. Our growing knowledges of IBD pathophysiology has led to the development of a multitude of new therapies over time, which may, 1 day, be able to address this unmet medical need. This review aims to provide physicians an update of emerging therapies in IBD by focusing on drugs currently in phase 3 clinical trials. Among the most promising molecules are anti-IL-23, JAK-inhibitors, anti-integrins and S1P modulators. While the results in terms of efficacy and safety are fairly clear for some classes, the question of safety remains more uncertain for other classes. Molecules at a more preliminary stage of development (phase 1 and 2), one of which may 1 day offer an optimal benefit-risk ratio, will also be presented as well as their respective mechanisms of action.

COVID-19 and inflammatory bowel disease crosstalk: From emerging association to clinical proposal

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can cause coronavirus disease 2019 (COVID-19), an acute respiratory inflammation that has emerged worldwide since December 2019, and it quickly became a global epidemic. Inflammatory bowel disease (IBD) is a group of chronic nonspecific intestinal inflammatory diseases whose etiology has not been elucidated. The two have many overlapping symptoms in clinical presentation, such as abdominal pain, diarrhea, pneumonia, etc. Imbalance of the autoimmune system in IBD patients and long-term use of immunosuppressive drugs may increase the risk of infection; and systemic symptoms caused by COVID-19 may also induce or exacerbate intestinal inflammation. It has been found that the SARS-CoV-2 receptor angiotensin converting enzyme 2, which is highly expressed in the lung and intestine, is an inflammatory protective factor, and is downregulated and upregulated in COVID-19 and IBD, respectively, suggesting that there may be a coregulatory pathway. In addition, the immune activation pattern of COVID-19 and the cytokine storm in the inflammatory response have similar roles in IBD, indicating that the two diseases may influence each other. Therefore, this review aimed to address the following research questions: whether SARS-CoV-2 infection leads to the progression of IBD; whether IBD increases the risk of COVID-19 infection and poor prognosis; possible common mechanisms and genetic cross-linking between the two diseases; new treatment and care strategies for IBD patients, and the feasibility and risk of vaccination in the context of the COVID-19 epidemic.

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.

Altered Bioavailability and Pharmacokinetics in Crohn's Disease: Capturing Systems Parameters for PBPK to Assist with Predicting the Fate of Orally Administered Drugs

Backgrond and Objective

Crohn’s disease (CD) is a chronic inflammatory bowel disease that affects a wide age range. Hence, CD patients receive a variety of drugs over their life beyond those used for CD itself. The changes to the integrity of the intestine and its drug metabolising enzymes and transporters (DMETs) can alter the oral bioavailability of drugs. However, there are other changes in systems parameters determining the fate of drugs in CD, and understanding these is essential for dose adjustment in patients with CD.

Methods

The current analysis gathered all the available clinical data on the kinetics of drugs in CD (by March 2021), focusing on orally administered small molecule drugs. A meta-analysis of the systems parameters affecting oral drug pharmacokinetics was conducted. The systems information gathered on intestine, liver and blood proteins and other physiological parameters was incorporated into a physiologically based pharmacokinetic (PBPK) platform to create a virtual population of CD patients, with a view for guiding dose adjustment in the absence of clinical data in CD.

Results

There were no uniform trends in the reported changes in reported oral bioavailability. The nature of the drug as well as the formulation affected the direction and magnitude of variation in kinetics in CD patients relative to healthy volunteers. Even for the same drug, the reported changes in exposure varied, possibly due to a lack of distinction between the activity states of CD. The highest alteration was seen with S-verapamil and midazolam, 8.7- and 5.3-fold greater exposure, respectively, in active CD patients relative to healthy volunteers. Only one report was available on liver DMETs in CD, and indicated reduced CYP3A4 activity. In a number of reports, mRNA expression of DMETs in the ileum and colon of CD patients was measured, focussing on P-glycoprotein (p-gp) transporter and CYP3A4 enzyme, and showed contradictory results. No data were available on protein expression in duodenum and jejunum despite their dominant role in oral drug absorption.

Conclusion

There are currently inadequate dedicated clinical or quantitative proteomic studies in CD to enable predictive PBPK models with high confidence and adequate verification. The PBPK models for CD with the available systems parameters were able to capture the major physiological influencers and the gaps to be filled by future research. Quantification of DMETs in the intestine and the liver in CD is warranted, alongside well-defined clinical drug disposition studies with a number of index drugs as biomarkers of changes in DMETs in these patients, to avoid large-scale dedicated studies for every drug to determine the effects of disease on the drug’s metabolism and disposition and the consequential safety and therapeutic concerns.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-022-01169-4.

SARS-CoV-2 and the central nervous system: Emerging insights into hemorrhage-associated neurological consequences and therapeutic considerations

Coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to impact our lives by causing widespread illness and death and poses a threat due to the possibility of emerging strains. SARS-CoV-2 targets angiotensin-converting enzyme 2 (ACE2) before entering vital organs of the body, including the brain. Studies have shown systemic inflammation, cellular senescence, and viral toxicity-mediated multi-organ failure occur during infectious periods. However, prognostic investigations suggest that both acute and long-term neurological complications, including predisposition to irreversible neurodegenerative diseases, can be a serious concern for COVID-19 survivors, especially the elderly population. As emerging studies reveal sites of SARS-CoV-2 infection in different parts of the brain, potential causes of chronic lesions including cerebral and deep-brain microbleeds and the likelihood of developing stroke-like pathologies increases, with critical long-term consequences, particularly for individuals with neuropathological and/or age-associated comorbid conditions. Our recent studies linking the blood degradation products to genome instability, leading to cellular senescence and ferroptosis, raise the possibility of similar neurovascular events as a result of SARS-CoV-2 infection. In this review, we discuss the neuropathological consequences of SARS-CoV-2 infection in COVID survivors, focusing on possible hemorrhagic damage in brain cells, its association to aging, and the future directions in developing mechanism-guided therapeutic strategies.

Impact of Immunotherapies on SARS-CoV-2-Infections and Other Respiratory Tract Infections during the COVID-19 Winter Season in IBD Patients

Background

COVID-19 represents one of the most significant medical problems of our time.

Aims

This study is focused on the question whether patients with inflammatory bowel disease (IBD) who receive immunotherapies are more vulnerable to respiratory tract infections and SARS-CoV-2 infections in comparison to medical staff, as a cohort with an increased infection risk, and to the general population in a COVID-19 hotspot.

Methods

We analysed data regarding respiratory tract infections that were collected in our IBD registry and compared them with corresponding data from medical employees in our associated Isarklinikum hospital and from the healthy general population in Munich, Germany, over the same time frame in April and June 2020. Patients were tested for SARS-CoV-2 immunoglobulins (Ig).

Results

Symptoms of respiratory tract infections occurred equally frequent in IBD patients with immunotherapies as compared to those without. Older age (>49 years), TNF-inhibitor, and ustekinumab treatment showed a significantly protective role in preventing respiratory tract symptomatic COVID-19 infections that occurred in 0.45% of all our 1.091 IBD patients. Of those, 1.8% were positive for SARS-CoV-2 Ig, identically to the general population of Munich with also 1.8% positivity. Whilst more than 3% of all COVID-19 subjects of the general population died during the first wave, none of our IBD patients died or needed referral to the ICU or oxygen treatment.

Conclusions

In our study, IBD patients are as susceptible to respiratory tract infections or SARS-CoV-2 as the normal population. There is no evidence of an association between IBD therapies and increased risk of COVID-19. Interestingly, a reduced rate of COVID-19 deaths in IBD patients, the majority on immunomodulator therapy, was observed, compared to the general population. Therefore, no evidence was found to suggest that IBD medication should be withheld, and adherence should be encouraged to prevent flares. In addition to older age (>49 years), TNF inhibitors and ustekinumab show a protective role in preventing respiratory tract infections. In addition, these results add to the growing evidence that supports further investigation of TNF inhibitors as a possible treatment in the early course of severe COVID-19.

COVID-19 in Patients with Inflammatory Bowel Disease: The Israeli Experience

Background: Crohn’s disease (CD) and ulcerative colitis (UC) are chronic, immune-mediated inflammatory bowel diseases (IBD) affecting millions of people worldwide. IBD therapies, designed for continuous immune suppression, often render patients more susceptible to infections. The effect of the immune suppression on the risk of coronavirus disease-19 (COVID-19) is not fully determined yet. Objective: To describe COVID-19 characteristics and outcomes and to evaluate the association between IBD phenotypes, infection outcomes and immunomodulatory therapies. Methods: In this multi-center study, we prospectively followed IBD patients with proven COVID-19. De-identified data from medical charts were collected including age, gender, IBD type, IBD clinical activity, IBD treatments, comorbidities, symptoms and outcomes of COVID-19. A multivariable regression model was used to examine the effect of immunosuppressant drugs on the risk of infection by COVID-19 and the outcomes. Results: Of 144 IBD patients, 104 (72%) were CD and 40 (28%) were UC. Mean age was 32.2 ± 12.6 years. No mortalities were reported. In total, 94 patients (65.3%) received biologic therapy. Of them, 51 (54%) at escalated doses, 10 (11%) in combination with immunomodulators and 9 (10%) with concomitant corticosteroids. Disease location, behavior and activity did not correlate with the severity of COVID-19. Biologics as monotherapy or with immunomodulators or corticosteroids were not associated with more severe infection. On the contrary, patients receiving biologics had significantly milder infection course (p = 0.001) and were less likely to be hospitalized (p = 0.001). Treatment was postponed in 34.7% of patients until recovery from COVID-19, without consequent exacerbation. Conclusion: We did not witness aggravated COVID-19 outcomes in patients with IBD. Patients treated with biologics had a favorable outcome.

Clinical Features and Pathophysiological Mechanisms of COVID-19-associated Gastrointestinal Manifestations

Aim and objective

According to the literature, gastrointestinal (GI) involvement may have a remarkable influence on the course of coronavirus disease-2019 (COVID-19). Our aim with this article is to appraise clinical characteristics and presumptive biological mechanisms of digestive tract involvement of COVID-19.

Background

In this review article, the English language literature was reviewed by using PubMed and MEDLINE databases, up to February 2021.

Review results

The patients with GI involvement are generally presented with diarrhea, nausea/vomiting, anorexia, abdominal pain, and rarely GI bleeding. However, frequencies of these manifestations are diverse in studies published so far, depending on the countries where the studies were conducted, characteristics of the study populations, and methodological differences. Several studies proved that this novel coronavirus gets into the enterocytes by attaching to angiotensin-converting enzyme 2 receptor. Some of them have shown a direct viral invasion and replication of the virus within enterocytes. Along with detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in patients' fecal materials, all these results explicitly indicate that the virus has the capability to invade the GI system. These findings may represent a potential risk indicator for fecal-oral spread of the virus. Although pathophysiology of COVID-19 associated GI manifestations remains elusive, direct viral damage, dysfunction in renin-angiotensin-aldosterone system, effects of gut-lung axis, and GI tract microbiome dysbiosis have been proposed as culprit mechanisms of the GI symptoms and inflammatory response.

Conclusion

The patients with COVID-19 can be presented with diverse clinical manifestations including the GI symptoms. Understanding the actual impact of the virus on the GI tract depends on uncovering the pathophysiology of COVID-19.

Clinical significance

GI involvement of COVID-19 appears to be crucial not only for its clinical consequences but also for its impacts on public health and prevention.

How to cite this article

Aslan AT, Şimşek H. Clinical Features and Pathophysiological Mechanisms of COVID-19-associated Gastrointestinal Manifestations. Euroasian J Hepato-Gastroenterol 2021;11(2):81-86.

Impact of COVID-19 on Pediatric Immunocompromised Patients

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Risk, Course, and Effect of SARS-CoV-2 Infection in Children and Adults with Chronic Inflammatory Bowel Diseases

Susceptibility and disease course of COVID-19 among patients with inflammatory bowel diseases (IBD) are unclear and epidemiological data on the topic are still limited. There is some concern that patients with immuno-mediated diseases such as IBD, which are frequently treated with immunosuppressive therapies, may have an increased risk of SARS-CoV-2 infection with its related serious adverse outcomes, including intensive care unit (ICU) admission and death. Corticosteroids, immunomodulators, and biologic drugs, which are commonly prescribed to these patients, have been associated with higher rates of severe viral and bacterial infections including influenza and pneumonia. It is not known whether these drugs can be so harmful as to justify their interruption during COVID-19 infection or if, on the contrary, patients with IBD can benefit from them. As shown by recent reports, it cannot be excluded that drugs that suppress the immune system can block the characteristic cytokine storm of severe forms of COVID-19 and consequently reduce mortality. Another cause for concern is the up-regulation of angiotensin converting enzyme-2 (ACE2) receptors that has been noticed in these patients, which could facilitate the entry and replication of SARS-CoV-2. The aim of this narrative review is to clarify the susceptibility of SARS-CoV-2 infection in patients with IBD, the clinical characteristics of patients who contract the infection, and the relationship between the severity of COVID-19 and immunosuppressive treatment.

Which ones, when and why should renin-angiotensin system inhibitors work against COVID-19?

The article describes the possible pathophysiological origin of COVID-19 and the crucial role of renin-angiotensin system (RAS), providing several “converging” evidence in support of this hypothesis. SARS-CoV-2 has been shown to initially upregulate ACE2 systemic activity (early phase), which can subsequently induce compensatory responses leading to upregulation of both arms of the RAS (late phase) and consequently to critical, advanced and untreatable stages of COVID-19 disease. The main and initial actors of the process are ACE2 and ADAM17 zinc-metalloproteases, which, initially triggered by SARS-CoV-2 spike proteins, work together in increasing circulating Ang 1–7 and Ang 1–9 peptides and downstream (Mas and Angiotensin type 2 receptors) pathways with anti-inflammatory, hypotensive and antithrombotic activities. During the late phase of severe COVID-19, compensatory secretion of renin and ACE enzymes are subsequently upregulated, leading to inflammation, hypertension and thrombosis, which further sustain ACE2 and ADAM17 upregulation. Based on this hypothesis, COVID-19-phase-specific inhibition of different RAS enzymes is proposed as a pharmacological strategy against COVID-19 and vaccine-induced adverse effects. The aim is to prevent the establishment of positive feedback-loops, which can sustain hyperactivity of both arms of the RAS independently of viral trigger and, in some cases, may lead to Long-COVID syndrome.

Impact of the COVID-19 pandemic on inflammatory bowel disease patients: A review of the current evidence

Since the initial coronavirus disease 2019 (COVID-19) outbreak in China in December 2019, the infection has now become the biggest medical issue of modern medicine. Two major contributors that amplified the impact of the disease and subsequently increased the burden on health care systems were high mortality among patients with multiple co-morbidities and overcapacity of intensive care units. Within the gastroenterology-related community, particular concern was raised with respect to patients with inflammatory bowel disease (IBD), as those patients are prone to opportunistic infections mainly owing to their immunosuppressive-based therapies. Hence, we sought to summarize current knowledge regarding COVID-19 infection in patients with IBD. Overall, it seems that IBD is not a comorbidity that poses an increased risk for COVID-19 acquisition, except in patients treated with 5-aminosalicylates. Furthermore, outcomes of the infected patients are largely dependent on therapeutic modality by which they are treated, as some worsen the clinical course of COVID-19 infection, whereas others seem to dampen the detrimental effects of COVID-19. Finally, we discussed the present and the future impact of COVID-19 pandemic and concomitantly increased health care burden on IBD-management.

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.

COVID-19 in gastroenterology and hepatology: Lessons learned and questions to be answered

BACKGROUND

Although coronavirus disease 2019 (COVID-19) presents primarily as a lower respiratory tract infection, increasing data suggests multiorgan, including the gastrointestinal (GI) tract and liver, involvement in patients who are infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

AIM

To provide a comprehensive overview of COVID-19 in gastroenterology and hepatology.

METHODS

Relevant studies on COVID-19 related to the study aim were undertaken through a literature search to synthesize the extracted data.

RESULTS

We found that digestive symptoms and liver injury are not uncommon in patients with COVID-19 and varies in different individuals. The most common GI symptoms reported are diarrhea, nausea, vomiting, and abdominal discomfort. Other atypical GI symptoms, such as loss of smell and taste and GI bleeding, have also been reported along with the evolvement of COVID-19. Liver chemistry abnormalities mainly include elevation of aspartate transferase, alanine transferase, and total bilirubin. It is postulated to be related to the binding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus to the angiotensin converting enzyme-2 receptor located on several different human cells.

CONCLUSION

Standardized criteria should be established for diagnosis and grading of the severity of GI symptoms in COVID-19 patients. Gastroenterology and hepatology in special populations, such as children and elderly, should be the focus of further research. Future long-term data regarding GI symptoms should not be overlooked.

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.

Gastrointestinal and renal complications in SARS-CoV-2-infected patients: Role of immune system

The recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease has been accompanied by various gastrointestinal (GI) and renal manifestations in significant portion of infected patients. Beside studies on the respiratory complications of coronavirus infection, understanding the essential immunological processes underlying the different clinical manifestations of virus infection is crucial for the identification and development of effective therapies. In addition to the respiratory tract, the digestive and urinary systems are the major sources of virus transmission. Thus, knowledge about the invasion mechanisms of SARS-CoV-2 in these systems and the immune system responses is important for implementing the infection prevention strategies. This article presents an overview of the gut and renal complications in SARS-CoV-2 infection. We focus on how SARS-CoV-2 interacts with the immune system and the consequent contribution of immune system, gut, and renal dysfunctions in the development of disease.

SARS-CoV-2 Virus Manifestations in the Gastrointestinal Tract: Therapeutic Implications

BACKGROUND

About 1 year ago a novel virus - SARS-CoV-2 - began to spread around the world. It can lead to the disease COVID-19, which has caused more than 1 million deaths already.

SUMMARY

While it was first recognized as a disease leading to pneumonia and lung failure, we know by now that COVID-19 is more complex. COVID-19 is a systemic hyperinflammatory disease affecting not only the lungs, but also many other organs. Especially the gastrointestinal (GI) tract is often involved in COVID-19.

KEY MESSAGES

This review provides an overview of the different affected organs of the GI tract and offers information on how gastroenterologists should take care of their patients with different GI disorders.

What Do Influenza and COVID-19 Represent for Patients With Inflammatory Bowel Disease?

BACKGROUND

Inflammatory bowel diseases (IBD) are a group of immune and inflammatory diseases; and patients seem to be more vulnerable to influenza and coronavirus disease 2019 (COVID-19). These conditions are characterized by the augmented release of inflammatory cytokines that have been suggested as potential triggers for the acute respiratory distress syndrome, which may favor severe and even fatal outcomes. For these reasons, this review aims to evaluate what influenza and COVID-19 may represent for patients with IBD.

METHODS

The search was performed in MEDLINE/PubMed, EMBASE, and Cochrane databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to build the review.

RESULTS

The conventional therapies used by IBD patients may also interfere in the outcomes of influenza and COVID-19. Immune-suppressors agents are associated with a higher risk of infections due to the inhibition of intracellular signals necessary to the host act against pathogens. On the other hand, drugs related to the suppression of the production of cytokines in IBD could bring benefits to reduce mucosal inflammation, and for preventing pneumonia. Moreover, coronaviruses can bind to the target cells through angiotensin-converting enzyme 2 (ACE-2) receptor that is expressed in epithelial cells of the lung and largely the colon and the terminal ileum suggesting that human intestinal tract could be an alternative route for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

CONCLUSIONS

Once the cytokine storm observed in influenza and COVID-19 is similar to the cytokine pattern observed in IBD patients during the disease flares, the advice is that avoiding the infections is still an optimal option for IBD subjects.

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.

Unraveling the Role of ACE2, the Binding Receptor for SARS-CoV-2, in Inflammatory Bowel Disease

Angiotensin-converting enzyme 2 (ACE2) has been highlighted for its role as a receptor for SARS-CoV-2, responsible for the current COVID-19 pandemic. This review summarizes current knowledge about ACE2 as a multifunctional protein, focusing on its relevance in inflammatory bowel disease (IBD). As an enzyme, ACE2 may be protective in IBD because it favors the counter-regulatory arm of the renin-angiotensin system or deleterious because it metabolizes other anti-inflammatory/repairing elements. Meanwhile, as a receptor for SARS-CoV-2, the impact of ACE2 expression/activity on infection is still under debate because no direct evidence has been reported and, again, both protective and deleterious pathways are possible. Research has shown that ACE2 regulates the expression of the neutral amino acid transporter B0AT1, controlling tryptophan-associated intestinal inflammation and nutritional status. Finally, intact membrane-bound or shed soluble ACE2 can also trigger integrin signaling, modulating the response to anti-integrin biologic drugs used to treat IBD (such as vedolizumab) and fibrosis, a long-term complication of IBD. As such, future studies on ACE2 expression/activity in IBD can improve monitoring of the disease and explore an alternative pharmacological target.

COVID-19 in patients with inflammatory bowel disease: A systematic review of clinical data

BACKGROUND

Great efforts by the scientific community are rapidly expanding the evidence on the clinical interplay between Covid-19 and inflammatory bowel disease (IBD).

AIMS

We performed a systematic review of the literature on published Covid-19 cases occurring in patients with IBD.

METHODS

PubMed Central/Medline and Embase were systemically searched for records up to May 31, 2020.

RESULTS

13 cohort studies and 5 single case reports were included in the qualitative synthesis. A cumulative number of approximately 800 patients with IBD and Covid-19 were identified. The case fatality rate ranged from 0% to 20.0%. Overall, immunomodulators and biologics were not associated with higher risk of Covid-19 or with negative outcomes, while the use of systemic corticosteroids was related to worse prognosis in some studies.

CONCLUSIONS

This systematic review highlighted two main points that may help clinicians dealing with IBD in reassuring their patients: (1) patients with IBD do not seem to be at higher risk of being infected by SARS-COV-2 than the general population; (2) in case of Covid-19, treatment with immunomodulators or biologics is not associated with worse prognosis, while systemic steroids are suspected to be potentially detrimental, even if more data are needed to confirm this point.

Prevalence and Outcomes of COVID-19 Among Patients With Inflammatory Bowel Disease-A Danish Prospective Population-based Cohort Study

BACKGROUND AND AIMS

As no population-based study has investigated the susceptibility and disease course of COVID-19 among patients with inflammatory bowel diseases [IBD], we aimed to investigate this topic in a population-based setting.

METHODS

Two cohorts were investigated. First, a nationwide cohort of all IBD patients diagnosed with COVID-19 was prospectively followed to investigate the disease courses of both diseases. Second, within a population-based cohort of 2.6 million Danish citizens, we identified all individuals tested for SARS-CoV-2 to determine the occurrence of COVID-19 among patients with and without IBD and other immune-mediated inflammatory diseases [IMIDs].

RESULTS

Between January 28, 2020 and June 2, 2020, a total of 76 IBD patients with COVID-19 were identified in the national cohort and prospectively followed for 35 days (interquartile range [IQR]: 25-51). A large proportion [n = 19: 25%] required a COVID-19-related hospitalisation for 7 days [IQR: 2-8.5] which was associated with being 65 years or older (odds ratio [OR] = 23].80, 95% confidence interval [CI] 6.32-89.63, p <0.01) and presence of any non-IMID comorbidity [OR = 8.12, 95% CI 2.55-25.87, p <0.01], but not use of immunomodulators [p = 0.52] or biologic therapies [p = 0.14]. In the population-based study, 8476 of 231 601 [3.7%] residents tested positive for SARS-CoV-2; however, the occurrence was significantly lower among patients with IBD [62 of the 2486 patients = 2.5%, p <0.01] and other IMIDs [531 of 16 492 patients = 3.2%, p <0.01] as compared with patients without IMIDs.

CONCLUSIONS

Patients with IMIDs, including IBD, had a significantly lower susceptibility to COVID-19 than patients without IMIDs, and neither immunosuppressive therapies nor IBD activity were associated with the disease course of COVID-19.

Review of inflammatory bowel disease and COVID-19

The first cases of a novel corona virus infection were reported in Wuhan China in December of 2019, followed by the declaration of an international pandemic by the World Health Organization in March 2020. Early reports of the virus, now known as severe acute respiratory syndrome coronavirus 2, and its clinical disease coronavirus disease 2019 (COVID-19), has shown higher rates of morbidity and mortality in the elderly and those with pre-existing medical conditions. Of particular concern is the safety of those with compromised immune systems. Inflammatory Bowel disease (IBD) is itself caused by a disordered immune response, with the most effective medical therapies being immune suppressing or modifying. As such, the risk of COVID-19, virus related outcomes, and appropriate management of IBD patients during the global pandemic is of immediate concern to gastroenterologists worldwide. There has been a rapid accumulation of clinical data and expert opinion on the topic. This review will highlight the latest source information on clinical observation/outcomes of the IBD population and provide a concise summary of the most up to date perspectives on IBD management in the age of COVID-19.

Gastrointestinal insights during the COVID-19 epidemic

Coronavirus disease-2019 (COVID-19) has so far caused hundreds of mortalities worldwide. Although respiratory symptoms are the main complication in COVID-19 patients, the disease is also associated with gastrointestinal problems, with diarrhea, nausea, and vomiting being primary COVID-19 symptoms. Thus, cancer and inflammatory bowel disease (IBD) management, stool viral tests, and virus exposure are major concerns in the context of COVID-19 epidemic. In patients with colorectal cancer and IBD, the colonic mucosa exhibits elevated angiotensin-converting enzyme 2 receptor levels, enhancing COVID-19 susceptibility. In some cases, positive viral stool tests may be the only indicator of infection at admission or after leaving quarantine. Without supplemental stool tests, the risk of undetected COVID-19 transmission is high. Moreover, viral exposure during the regular or emergency endoscopic examination should be avoided. We carefully discuss key gastrointestinal concerns with regard to COVID-19 and call for more attention to such problems.

The Interplay Between Genetic Risk Factors and Proteolytic Dysregulation in the Pathophysiology of Inflammatory Bowel Disease

Crohn's disease [CD] and ulcerative colitis [UC] are the two main forms of inflammatory bowel disease [IBD]. Previous studies reported increased levels of proteolytic activity in stool and tissue samples from IBD patients, whereas the re-establishment of the proteolytic balance abrogates the development of experimental colitis. Furthermore, recent data suggest that IBD occurs in genetically predisposed individuals who develop an abnormal immune response to intestinal microbes once exposed to environmental triggers. In this review, we highlight the role of proteases in IBD pathophysiology, and we showcase how the main cellular pathways associated with IBD influence proteolytic unbalance and how functional proteomics are allowing the unambiguous identification of dysregulated proteases in IBD, paving the way to the development of new protease inhibitors as a new potential treatment.

Characterization of the inflammatory-metabolic phenotype of heart failure with a preserved ejection fraction: a hypothesis to explain influence of sex on the evolution and potential treatment of the disease

Accumulating evidence points to the existence of an inflammatory-metabolic phenotype of heart failure with a preserved ejection fraction (HFpEF), which is characterized by biomarkers of inflammation, an expanded epicardial adipose tissue mass, microvascular endothelial dysfunction, normal-to-mildly increased left ventricular volumes and systolic blood pressures, and possibly, altered activity of adipocyte-associated inflammatory mediators. A broad range of adipogenic metabolic and systemic inflammatory disorders - e.g. obesity, diabetes and metabolic syndrome as well as rheumatoid arthritis and psoriasis - can cause this phenotype, independent of the presence of large vessel coronary artery disease. Interestingly, when compared with men, women are both at greater risk of and may suffer greater cardiac consequences from these systemic inflammatory and metabolic disorders. Women show disproportionate increases in left ventricular filling pressures following increases in central blood volume and have greater arterial stiffness than men. Additionally, they are particularly predisposed to epicardial and intramyocardial fat expansion and imbalances in adipocyte-associated proinflammatory mediators. The hormonal interrelationships seen in inflammatory-metabolic phenotype may explain why mineralocorticoid receptor antagonists and neprilysin inhibitors may be more effective in women than in men with HFpEF. Recognition of the inflammatory-metabolic phenotype may improve an understanding of the pathogenesis of HFpEF and enhance the ability to design clinical trials of interventions in this heterogeneous syndrome.

The Thrilling Journey of SARS-CoV-2 into the Intestine: From Pathogenesis to Future Clinical Implications

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has a direct impact on the gastrointestinal system, as up to 50% of fecal samples from coronavirus disease 2019 (COVID-19) patients contain detectable viral RNA despite a negative rhino-pharyngeal swab. This finding, together with an intestinal expression of angiotensin conversion enzyme 2 protein, suggests a possible fecal-oral transmission for SARS-CoV-2. Furthermore, gastrointestinal (GI) symptoms are common in COVID-19 patients including watery diarrhea, vomiting-particularly in children-nausea, and abdominal pain. Pathogenesis of SARS-CoV-2 infection presents significant similarities to those of some immune-mediated diseases, such as inflammatory bowel diseases or rheumatoid arthritis, leading to the hypothesis that targeted therapies used for the treatment of immune-mediated disease could be effective to treat (and possibly prevent) the main complications of COVID-19. In this review, we synthesize the present and future impact of SARS-CoV-2 infection on the gastrointestinal system and on gastroenterology practice, hypothesizing a potential role of the "gut-lung axis" and perhaps of the gut and lung microbiota into the interindividual differential susceptibility to COVID-19 19 disease. Finally, we speculate on the reorganization of outpatient gastroenterology services, which need to consider, among other factors, the major psychological impact of strict lockdown measures on the whole population.

Genetic deletion of the angiotensin-(1-7) receptor Mas leads to alterations in gut villi length modulating TLR4/PI3K/AKT and produces microbiome dysbiosis

Renin-Angiotensin System (RAS) is an important peptide cascade involved in physiological processes. RAS homeostasis disruption produces several cardiovascular and metabolic disorders, such as arterial hypertension, atherosclerosis, acute myocardial infarct, obesity, diabetes, metabolic syndrome and increases gastrointestinal tract (GIT) cell proliferation. Angiotensin (Ang)-(1-7) peptide is the main RAS counter-regulatory axis effector. It is formed from ACE2 enzyme and acts mainly through Mas receptor (MasR). In this context, the aim of the present study was to evaluate alterations in small intestine morphology and intestinal microbiota composition in MasR knockout C57BL/6 mice. We analyzed glucose tolerance; insulin sensitivity and blood collected for biochemical parameters as well as small intestine tissues samples for immunohistochemistry. mRNA and bacteria gDNA expression evaluation. mRNA expression was evaluated by qRT-PCR for TLR4, PI3K and AKT. The main results showed that Mas-R-knockout mice presented lower body weight. MasR-knockout mice also presented increased fasted blood glucose and total cholesterol with reduced HDL, lower glucose tolerance and impaired insulin sensitivity. Increased intestinal mucosa length, increased intestinal villi, reduced Lieberkühn crypt depth. The increased expression of cell proliferation markers Ki-67 and Cyclin D1 and increased TLR4, PI3K and AKT expressions were observed with augmented Bacteroidetes and decreased amount of Firmicutes. That results suggests that MasR deletion generated changes in intestinal microbiota, possibly due to a lower neutral amino acids absorption followed by a compensatory increase in intestinal villi length associated with disbiosis and LPS overproduction that ultimately lead to proliferation and cell inflammation.

The Yin and Yang of ACE/ACE2 Pathways: The Rationale for the Use of Renin-Angiotensin System Inhibitors in COVID-19 Patients

The article describes the rationale for inhibition of the renin-angiotensin system (RAS) pathways as specific targets in patients infected by SARS-CoV-2 in order to prevent positive feedback-loop mechanisms. Based purely on experimental studies in which RAS pathway inhibitors were administered in vivo to humans/rodents, a reasonable hypothesis of using inhibitors that block both ACE and ACE2 zinc metalloproteases and their downstream pathways in COVID-19 patients will be proposed. In particular, metal (zinc) chelators and renin inhibitors may work alone or in combination to inhibit the positive feedback loops (initially triggered by SARS-CoV-2 and subsequently sustained by hypoxia independently on viral trigger) as both arms of renin-angiotensin system are upregulated, leading to critical, advanced and untreatable stages of the disease.

COVID-19 and Inflammatory Bowel Diseases: Risk Assessment, Shared Molecular Pathways, and Therapeutic Challenges

Background

The novel coronavirus SARS-CoV-2 causing COVID-19 disease is yielding a global outbreak with severe threats to public health. In this paper, we aimed at reviewing the current knowledge about COVID-19 infectious risk status in inflammatory bowel disease (IBD) patients requiring immunosuppressive medication. We also focused on several molecular insights that could explain why IBD patients appear not to have higher risks of infection and worse outcomes in COVID-19 than the general population in an attempt to provide scientific support for safer decisions in IBD patient care.

Methods

PubMed electronic database was interrogated for relevant articles involving data about common molecular pathways and shared treatment strategies between SARS-CoV-2, SARS-CoV-1, MERS-CoV, and inflammatory bowel diseases. Besides, Neural Covidex, an artificial intelligence tool, was used to answer queries about pathogenic coronaviruses and possible IBD interactions using the COVID-19 Open Research Dataset (CORD-19). Discussions. Few molecular and therapeutic interactions between IBD and pathogenic coronaviruses were explored. First, we showed how the activity of soluble angiotensin-converting enzyme 2, CD209L other receptors, and phosphorylated α subunit of eukaryotic translation initiation factor 2 might exert protective impact in IBD in case of coronavirus infection. Second, IBD medication was discussed in the context of possible beneficial effects on COVID-19 pathogeny, including “cytokine storm” prevention and treatment, immunomodulation, interferon signaling blocking, and viral endocytosis inhibition.

Conclusions

Using the current understanding of SARS-CoV-2 as well as other pathogenic coronaviruses immunopathology, we showed why IBD patients should not be considered at an increased risk of infection or more severe outcomes. Whether our findings are entirely applicable to the pathogenesis, disease susceptibility, and treatment management of SARS-CoV-2 infection in IBD must be further explored.

Angiotensin converting enzyme: A review on expression profile and its association with human disorders with special focus on SARS-CoV-2 infection

Angiotensin-converting enzyme (ACE) and its homologue, ACE2, have been mostly associated with hypertensive disorder. However, recent pandemia of SARS-CoV-2 has put these proteins at the center of attention, as this virus has been shown to exploit ACE2 protein to enter cells. Clear difference in the response of affected patients to this virus has urged researchers to find the molecular basis and pathophysiology of the cell response to this virus. Different levels of expression and function of ACE proteins, underlying disorders, consumption of certain medications and the existence of certain genomic variants within ACE genes are possible explanations for the observed difference in the response of individuals to the SARS-CoV-2 infection. In the current review, we discuss the putative mechanisms for this observation.

Aspects of inflammatory bowel disease during the COVID-19 pandemic and general considerations

So far, available evidence suggests that patients with inflammatory bowel disease (IBD) are not at greater risk for developing COVID-19 infection. In regard to patients with IBD remission: 5-aminosalycylates (5-ASAs) do not increase the risk for infection and should be continued. There is no need to suspend them or lower the dose. Immunomodulating drugs, such as thiopurines and methotrexate, should be continued, without modifying doses (even in patients with positive SARS-CoV-2 infection). No type of biologic therapy should be suspended, unless there are signs of COVID-19. Regarding patients with IBD activity: the oral and/or topical 5-ASA dose should be optimized in cases of disease relapse. Budesonide MMX should be considered in cases of mild-to-moderate activity, to avoid systemic steroid use. Systemic steroids should be avoided whenever possible because doses above 20mg per day have an immunosuppressive effect, which could increase susceptibility to any type of infection, including COVID-19. The combined use of thiopurines with steroids and/or tumor necrosis factor (TNF) monoclonal antibodies should also be avoided because those combinations can increase the risk for infections, including COVID-19. Finally, biologic treatment with anti-TNF-alpha agents or any other mechanism of action, such as anti-integrins or anti-interleukins, should be suspended if patients become infected with SARS-CoV-2. The drugs can be restarted once the infectious process is resolved.

IBD Patients Could Be Silent Carriers for Novel Coronavirus and Less Prone to its Severe Adverse Events: True or False?

Inflammatory bowel diseases (IBDs) are chronic disorders of the gastrointestinal tract. The goal of IBD treatment is to reduce the inflammation period and induce long-term remission. Use of anti-inflammatory drugs including corticosteroids, immunosuppressants and biologicals, is often the first step in the treatment of IBD. Therefore, IBD patients in pandemic of infectious diseases are considered a high-risk group. The public believes that IBD patients are at a higher risk in the current coronavirus 2 pandemic. Nevertheless, these patients may experience mild or moderate complications compared to healthy people. This might be because of particular anti-TNF-α treatment or any immunosuppressant that IBD patients receive. Moreover, these patients might be silent carrier for the virus.

Angiotensin-converting enzyme 2 (ACE2), SARS-CoV-2 and the pathophysiology of coronavirus disease 2019 (COVID-19)

Angiotensin-converting enzyme 2 (ACE2) has been established as the functional host receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the current devastating worldwide pandemic of coronavirus disease 2019 (COVID-19). ACE2 is abundantly expressed in a variety of cells residing in many different human organs. In human physiology, ACE2 is a pivotal counter-regulatory enzyme to ACE by the breakdown of angiotensin II, the central player in the renin-angiotensin-aldosterone system (RAAS) and the main substrate of ACE2. Many factors have been associated with both altered ACE2 expression and COVID-19 severity and progression, including age, sex, ethnicity, medication, and several co-morbidities, such as cardiovascular disease and metabolic syndrome. Although ACE2 is widely distributed in various human tissues and many of its determinants have been well recognised, ACE2-expressing organs do not equally participate in COVID-19 pathophysiology, implying that other mechanisms are involved in orchestrating cellular infection resulting in tissue damage. Reports of pathologic findings in tissue specimens of COVID-19 patients are rapidly emerging and confirm the established role of ACE2 expression and activity in disease pathogenesis. Identifying pathologic changes caused by SARS-CoV-2 infection is crucially important as it has major implications for understanding COVID-19 pathophysiology and the development of evidence-based treatment strategies. Currently, many interventional strategies are being explored in ongoing clinical trials, encompassing many drug classes and strategies, including antiviral drugs, biological response modifiers, and RAAS inhibitors. Ultimately, prevention is key to combat COVID-19 and appropriate measures are being taken accordingly, including development of effective vaccines. In this review, we describe the role of ACE2 in COVID-19 pathophysiology, including factors influencing ACE2 expression and activity in relation to COVID-19 severity. In addition, we discuss the relevant pathological changes resulting from SARS-CoV-2 infection. Finally, we highlight a selection of potential treatment modalities for COVID-19. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

COVID-19 and immunomodulation in IBD

The current coronavirus pandemic is an ongoing global health crisis due to COVID-19, caused by severe acute respiratory syndrome coronavirus 2. Although COVID-19 leads to little or mild flu-like symptoms in the majority of affected patients, the disease may cause severe, frequently lethal complications such as progressive pneumonia, acute respiratory distress syndrome and organ failure driven by hyperinflammation and a cytokine storm syndrome. This situation causes various major challenges for gastroenterology. In the context of IBD, several key questions arise. For instance, it is an important question to understand whether patients with IBD (eg, due to intestinal ACE2 expression) might be particularly susceptible to COVID-19 and the cytokine release syndrome associated with lung injury and fatal outcomes. Another highly relevant question is how to deal with immunosuppression and immunomodulation during the current pandemic in patients with IBD and whether immunosuppression affects the progress of COVID-19. Here, the current understanding of the pathophysiology of COVID-19 is reviewed with special reference to immune cell activation. Moreover, the potential implications of these new insights for immunomodulation and biological therapy in IBD are discussed.