Altered aryl-hydrocarbon-receptor signalling affects regulatory and effector cell immunity in autoimmune hepatitis.

BACKGROUND & AIMS: In autoimmune hepatitis (AIH), the imbalance between regulatory T cells (Tregs) and T-helper type 17 (Th17) cells has been linked to low levels of CD39, an ectoenzyme that hydrolyses ATP, ultimately generating immunosuppressive adenosine. Upregulation of CD39 results from activation of aryl hydrocarbon receptor (AHR), which mediates toxin responses to modulate T-cell immunity. In this study, we investigated whether altered AHR signalling underlies defective CD39 expression and function in AIH Tregs and Th17 cells, therefore contributing to regulatory/effector cell imbalance. METHODS: Tregs and Th17 cells, obtained from the peripheral blood of 49 patients with AIH and 21 healthy individuals (HI), were tested for response to endogenous and exogenous AHR ligands. RESULTS: When compared to those of HI, AIH-derived Tregs and Th17 cells displayed impaired responses to AHR activation, reflected by impaired upregulation of CD39, delayed increase in ectoenzymatic activity, and defective Treg suppressive function. These impairments resulted, at least in part, from heightened levels of AHRR and Erα in Tregs and high HIF-1α in Th17 cells, and were reverted upon molecular blockade. Importantly, in AIH-derived Tregs, the binding affinity of AHR was higher for Erα than ARNT. CONCLUSIONS: In AIH, high levels of AHRR and HIF-1α inhibit AHR signalling in Tregs and Th17 cells. AHR non-canonical binding to Erα further amplifies the lack of effective CD39 upregulation. Blockade of these inhibitory and/or non-canonical activation pathways represents a potential therapeutic approach to restore CD39 and immunohomeostasis in AIH. LAY SUMMARY: In patients with autoimmune hepatitis, the imbalance between regulatory T cells and T helper type-17 cells is linked to dysfunction of the aryl hydrocarbon receptor pathway, resulting from aberrant inhibition or non-canonical activation. These alterations impair Treg- and Th17 cell-induced upregulation of CD39, an ectoenzyme key to immunoregulation. Blockade of excessive inhibition or non-canonical activation of the aryl hydrocarbon receptor pathway might represent a novel therapeutic strategy to control inflammation while restoring immune balance in autoimmune hepatitis.

Endogenous antisense RNA curbs CD39 expression in Crohn's disease.

CD39 is an ectonucleotidase that initiates conversion of extracellular nucleotides into immunosuppressive adenosine. CD39 is expressed by regulatory T (Treg)-cells, where it mediates immunosuppression, and by a subset of T-helper (Th) 17-cells, where it limits pathogenicity. CD39 is regulated via single-nucleotide-polymorphisms and upon activation of aryl-hydrocarbon-receptor and oxygen-mediated pathways. Here we report a mechanism of CD39 regulation that relies on the presence of an endogenous antisense RNA, transcribed from the 3'-end of the human CD39/ENTPD1 gene. CD39-specific antisense is increased in Treg and Th17-cells of Crohn's disease patients over controls. It largely localizes in the cell nucleus and regulates CD39 by interacting with nucleolin and heterogeneous-nuclear-ribonucleoprotein-A1. Antisense silencing results in CD39 upregulation in vitro and amelioration of disease activity in a trinitro-benzene-sulfonic-acid model of colitis in humanized NOD/scid/gamma mice. Inhibition/blockade of antisense might represent a therapeutic strategy to restore CD39 along with immunohomeostasis in Crohn's disease.

Transaminitis is an indicator of mortality in patients with COVID-19: A retrospective cohort study.

BACKGROUND: Since its discovery in Wuhan, China in December of 2019, the novel coronavirus has progressed to become one of the worst pandemics seen in the last 100 years. Recently, there has been an increased interest in the hepatic manifestations of coronavirus disease 19 (COVID-19). AIM: To describe the demographic and clinical characteristics of COVID-19 positive patients and study the association between transaminitis and all-cause mortality. METHODS: This is a descriptive retrospective cohort study of 130 consecutive patients with a positive COVID PCR test admitted between March 16, 2020 to May 14, 2020 at a tertiary care University-based medical center. The Wilcoxon-rank sum test and paired t-test were used for comparing non-parametric and parametric continuous variables respectively and a multivariable logistic regression models to study the association between transaminitis and mortality using SAS version 9.4 (SAS Institute, Cary, NC, United States). RESULTS: Out of the 130 patients, 73 (56%) patients were found to have transaminitis and 57 (44%) did not. When compared to patients without transaminitis, the transaminitis group was found to have a higher median body mass index (30.2 kg/m2 vs 27.3 kg/m2, P = 0.04). In the multivariate analysis those with transaminitis were found to have 3.4 times higher odds of dying as compared to those without transaminitis adjusting for gender, the Age-adjusted Charlson Comorbidity Index and admission to the intensive care unit (P = 0.03). CONCLUSION: Our study showed that transaminitis on admission was associated with severe clinical outcomes such as admission to the intensive care unit, need for mechanical ventilation, and mortality.

Bridging the Divisum: A Rare Case of Pancreaticopleural Fistula in the Setting of Complete Pancreatic Divisum Treated Endoscopically.

A pancreaticopleural fistula (PPF) is a rare complication of chronic pancreatitis that occurs either due to a pancreatic duct disruption or a pseudocyst extension. A pancreatic divisum, on the other hand, is a common anatomic variant of the pancreas that is rarely symptomatic. We describe a case of recurrent pleural effusion in a patient with a history of chronic pancreatitis. Investigations revealed the presence of a PPF and a concomitant complete pancreatic divisum. There was resolution of the pleural effusion on endoscopic therapy. This is the fourth reported case of a PPF in the setting of complete pancreatic divisum and the first reported case in a middle-aged female.

Control of Gut Inflammation by Modulation of Purinergic Signaling.

Inflammatory bowel disease (IBD) is a serious inflammatory condition of the gastrointestinal tract. Crohn's disease (CD) and ulcerative colitis (UC) are two of the most common IBD manifestations and are both associated with unfettered inflammation, often refractory to conventional immunosuppressive treatment. In both conditions, imbalance between effector and regulatory cell immune responses has been documented and is thought to contribute to disease pathogenesis. Purinergic signaling is a known modulator of systemic and local inflammation and growing evidences point to extracellular ATP/adenosine imbalance as a key determinant factor in IBD-associated immune dysregulation. In vitro and pre-clinical studies suggest a role for both ATP (P2) and adenosine (P1) receptors in dictating onset and severity of the disease. Moreover, our experimental data indicate ENTPD1/CD39 and CD73 ectoenzymes as pivotal modulators of intestinal inflammation, with clear translational importance. Here we will provide an updated overview of the current knowledge on the role of the purinergic signaling in modulating immune responses in IBD. We will also review and discuss the most promising findings supporting the use of purinergic-based therapies to correct immune dysregulation in CD and UC.

Necrobiotic Pulmonary Nodules in Ulcerative Colitis: Not Just a "Crohnic" Phenomenon.

Necrobiotic pulmonary nodules are an exceptionally rare extraintestinal manifestation of inflammatory bowel disease. Recognition is imperative because it may mimic other autoimmune pathologies such as granulomatosis with polyangiitis or sarcoidosis. We describe a 19-year-old man with a known history of ulcerative colitis who was found to possess bilateral pulmonary nodules on computed tomography imaging. Investigations that included an extensive autoimmune and infectious workup were inconclusive. Biopsy of the nodules revealed fibrinous exudate and palisading histiocytes that confirmed the diagnosis. He was started on prednisone therapy. A follow-up computed tomography a month later revealed near complete resolution.

Atraumatic Intercostal and Intrathoracic Liver Herniation Related to Influenza A.

Nontraumatic and spontaneous intercostal and intrathoracic herniations are defined as protrusions of intra-abdominal contents through acquired or congenital defects of the abdominal and thoracic walls without any proceeding trauma and are sparsely reported in the literature with less than 35 detailed case reports reported in the literature worldwide. Most of these cases result from abdominal trauma and are considered surgical emergencies. The content of these herniations, as reported in the literature, have classically been lungs and intra-abdominal organs. We report a case of nontraumatic intercostal and intrathoracic liver herniation, which was managed conservatively given minimal liver injury and rapidly improving symptoms.

Helicobacter pylori-Negative MALT Lymphoma Presenting as a Massive Recurrent Gastrointestinal Hemorrhage.

Primary gastric lymphoma is rare, representing 5% of all primary gastric neoplasms. The presenting complaints of gastric mucosa-associated lymphoid tissue (MALT) lymphoma are usually nonspecific. However, life-threatening gastrointestinal bleeding from the stomach is unusual and sparsely reported. While studies reveal an indolent course, we present a case that presented with massive and recurrent hematemesis leading to hypovolemic shock secondary to endoscopically confirmed MALT lymphoma, which was treated with radiotherapy to achieve remission. She had no autoimmune diseases and tested negative for Helicobacter pylori. Our case emphasizes the importance of early diagnosis and timely intensive radiotherapy of a localized but aggressive gastric MALT lymphoma.

Novelty in the gut: a systematic review and meta-analysis of the gastrointestinal manifestations of COVID-19.

BACKGROUND: The COVID-19 epidemic has affected over 2.6 million people across 210 countries. Recent studies have shown that patients with COVID-19 experience relevant gastrointestinal (GI) symptoms. We aimed to perform a systematic review and meta-analysis on the GI symptoms of COVID-19. METHODS: A literature search was conducted via electronic databases, including PubMed, Embase, Scopus, and Google Scholar, from inception until 20 March 2020. Data were extracted from relevant studies. A systematic review of GI symptoms and a meta-analysis comparing symptoms in severe and non-severe patients was performed using RevMan V.5.3. RESULTS: Pooled data from 2477 patients with a reverse transcription-PCR-positive COVID-19 infection across 17 studies were analysed. Our study revealed that diarrhoea (7.8%) followed by nausea and/or vomiting (5.5 %) were the most common GI symptoms. We performed a meta-analysis comparing the odds of having GI symptoms in severe versus non-severe COVID-19-positive patients. 4 studies for nausea and/or vomiting, 5 studies for diarrhoea and 3 studies for abdominal pain were used for the analyses. There was no significant difference in the incidence of diarrhoea (OR=1.32, 95% CI 0.8 to 2.18, Z=1.07, p=0.28, I2=17%) or nausea and/or vomiting (OR=0.96, 95% CI 0.42 to 2.19, Z=0.10, p=0.92, I2=55%) between either group. However, there was seven times higher odds of having abdominal pain in patients with severe illness when compared with non-severe patients (OR=7.17, 95% CI 1.95 to 26.34, Z=2.97, p=0.003, I2=0%). CONCLUSION: Our study has reiterated that GI symptoms are an important clinical feature of COVID-19. Patients with severe disease are more likely to have abdominal pain as compared with patients with non-severe disease.

Modulation of CD39 and Exogenous APT102 Correct Immune Dysfunction in Experimental Colitis and Crohn's Disease.

BACKGROUND AND AIMS: CD39/ENTPD1 scavenges pro-inflammatory nucleotides, to ultimately generate immunosuppressive adenosine, which has a central role in immune homeostasis. Global deletion of Cd39 increases susceptibility to experimental colitis while single nucleotide polymorphisms within the human CD39 promoter, and aberrant patterns of expression during experimental hypoxia, predispose to Crohn's disease. We aimed to define the impact of transgenic human CD39 [hTG] overexpression in experimental colitis and to model therapeutic effects using the recombinant apyrase APT102 in vivo. We also determined the in vitro effects of APT102 on phenotypic and functional properties of regulatory T-lymphocytes derived from patients with Crohn's disease. METHODS: Colitis was induced by administration of dextran sulfate sodium in wild-type [WT] or hTG mice, and, in another model, by adoptive transfer of CD45RBhigh cells with or without WT or hTG regulatory T cells [Treg]. In additional experiments, mice were treated with APT102. The effects of APT102 on phenotype and function of Treg and type-1 regulatory T [Tr1] cells were also evaluated, after purification from peripheral blood and lamina propria of Crohn's disease patients [n = 38]. RESULTS: Overexpression of human CD39 attenuated experimental colitis and protected from the deleterious effects of systemic hypoxia, pharmacologically induced by deferoxamine. Administration of APT102 in vivo enhanced the beneficial effects of endogenous Cd39 boosted by the administration of the aryl hydrocarbon receptor [AhR] ligand unconjugated bilirubin [UCB]. Importantly, supplemental APT102 restored responsiveness to AhR stimulation by UCB in Treg and Tr1 cells, obtained from Crohn's disease patients. CONCLUSIONS: hCD39 overexpression ameliorated experimental colitis and prevented hypoxia-related damage in vivo. Exogenous administration of APT102 boosted AhR-mediated regulatory effects in vivo while enhancing Treg functions in Crohn's disease in vitro.

HIF-1α-induced xenobiotic transporters promote Th17 responses in Crohn's disease.

In Crohn's disease, pathogenic Th17-cells express low levels of CD39 ectonucleotidase and are refractory to the immunosuppressive effects of unconjugated bilirubin (UCB), an endogenous ligand for aryl-hydrocarbon-receptor (AhR). This resistance to AhR ligation might be associated with alterations in responses to hypoxia. Limited exposure to hypoxia appears beneficial in acute tissue injury. However, in protracted inflammation, hypoxemia may paradoxically result in Th17-cell activation. We report here that in vitro exposure of Th17-cells from Crohn's disease patients to hypoxia limits responsiveness to AhR stimulation by UCB, as reflected by lower CD39 levels. Blockade of hypoxia-inducible-factor-1alpha (HIF-1α) upregulates CD39 and favors Th17-cell regulatory responses. Resistance of Th17-cells to AhR signaling results, in part, from HIF-1α-dependent induction of ATP-binding cassette (ABC) transporters: multidrug-resistance-protein-1 (MDR1) and multidrug-resistance-associated-protein-4 (MRP4). Increased ABC transporters promote efflux of suppressive AhR ligands, such as UCB, from Th17-cells. Inhibition of MDR1, MRP4 and/or HIF-1α with ritonavir (RTV) reconstitutes AhR function in Th17-cells, enhancing therapeutic effects of UCB in dextran-sulfate-sodium-induced experimental colitis. Deleterious effects of hypoxia on Th17-cells in Crohn's disease can be ameliorated either by inhibiting HIF-1α or by suppressing ABC transporters to increase UCB availability as an AhR substrate. Targeting HIF-1α-ABC transporters could provide innovative therapeutic pathways for IBD.

More of the Gut in the Lung: How Two Microbiomes Meet in ARDS.

In critically ill patients, lung and gut microbiomes undergo profound changes. Lung microbiome might become enriched with gut-associated microbes as recently demonstrated in sepsis and acute respiratory distress syndrome (ARDS). It has been proposed that in these conditions, bacteria from the gut might enter the lungs via translocation, a process facilitated by increased gut and alveolo-capillary permeability. In patients requiring mechanical ventilation after severe trauma, lung microbiome enrichment with gut-associated microbes was found to correlate with the development of ARDS. The lungs in ARDS are increasingly susceptible to opportunistic infections which can further perpetuate alveolar inflammation and injury. Undoubtedly, more research on the gut-lung crosstalk in critically ill patients is needed to identify causal relationships between the altered microbiome, infections, inflammation, and acute lung injury. With further insights, this area of investigation could lead to the development of novel, microbiome-targeted, and immunomodulation strategies with the potential to improve outcomes of critically ill patients with sepsis, trauma, and ARDS.