Macrophage RAGE activation is proinflammatory in NASH.

Intrahepatic macrophages in nonalcoholic steatohepatitis (NASH) are heterogenous and include proinflammatory recruited monocyte-derived macrophages. The receptor for advanced glycation endproducts (RAGE) is expressed on macrophages and can be activated by damage associated molecular patterns (DAMPs) upregulated in NASH, yet the role of macrophage-specific RAGE signaling in NASH is unclear. Therefore, we hypothesized that RAGE-expressing macrophages are proinflammatory and mediate liver inflammation in NASH. Compared with healthy controls, RAGE expression was increased in liver biopsies from patients with NASH. In a high-fat, -fructose, and -cholesterol-induced (FFC)-induced murine model of NASH, RAGE expression was increased, specifically on recruited macrophages. FFC mice that received a pharmacological inhibitor of RAGE (TTP488), and myeloid-specific RAGE KO mice (RAGE-MKO) had attenuated liver injury associated with a reduced accumulation of RAGE+ recruited macrophages. Transcriptomics analysis suggested that pathways of macrophage and T cell activation were upregulated by FFC diet, inhibited by TTP488 treatment, and reduced in RAGE-MKO mice. Correspondingly, the secretome of ligand-stimulated BM-derived macrophages from RAGE-MKO mice had an attenuated capacity to activate CD8+ T cells. Our data implicate RAGE as what we propose to be a novel and potentially targetable mediator of the proinflammatory signaling of recruited macrophages in NASH.

Extracellular Vesicles in Hepatobiliary Health and Disease.

Extracellular vesicles (EVs) are membrane-bound nanoparticles released by cells and are an important means of intercellular communication in physiological and pathological states. We provide an overview of recent advances in the understanding of EV biogenesis, cargo selection, recipient cell effects, and key considerations in isolation and characterization techniques. Studies on the physiological role of EVs have relied on cell-based model systems due to technical limitations of studying endogenous nanoparticles in vivo . Several recent studies have elucidated the mechanistic role of EVs in liver diseases, including nonalcoholic fatty liver disease, viral hepatitis, cholestatic liver disease, alcohol-associated liver disease, acute liver injury, and liver cancers. Employing disease models and human samples, the biogenesis of lipotoxic EVs downstream of endoplasmic reticulum stress and microvesicles via intracellular activation stress signaling are discussed in detail. The diverse cargoes of EVs including proteins, lipids, and nucleic acids can be enriched in a disease-specific manner. By carrying diverse cargo, EVs can directly confer pathogenic potential, for example, recruitment and activation of monocyte-derived macrophages in NASH and tumorigenicity and chemoresistance in hepatocellular carcinoma. We discuss the pathogenic role of EVs cargoes and the signaling pathways activated by EVs in recipient cells. We review the literature that EVs can serve as biomarkers in hepatobiliary diseases. Further, we describe novel approaches to engineer EVs to deliver regulatory signals to specific cell types, and thus use them as therapeutic shuttles in liver diseases. Lastly, we identify key lacunae and future directions in this promising field of discovery and development. © 2023 American Physiological Society. Compr Physiol 13:4631-4658, 2023.

Association of Obesity With COVID-19 Severity and Mortality: An Updated Systemic Review, Meta-Analysis, and Meta-Regression.

Background: Obesity affects the course of critical illnesses. We aimed to estimate the association of obesity with the severity and mortality in coronavirus disease 2019 (COVID-19) patients. Data Sources: A systematic search was conducted from the inception of the COVID-19 pandemic through to 13 October 2021, on databases including Medline (PubMed), Embase, Science Web, and Cochrane Central Controlled Trials Registry. Preprint servers such as BioRxiv, MedRxiv, ChemRxiv, and SSRN were also scanned. Study Selection and Data Extraction: Full-length articles focusing on the association of obesity and outcome in COVID-19 patients were included. Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were used for study selection and data extraction. Our Population of interest were COVID-19 positive patients, obesity is our Intervention/Exposure point, Comparators are Non-obese vs obese patients The chief outcome of the study was the severity of the confirmed COVID-19 positive hospitalized patients in terms of admission to the intensive care unit (ICU) or the requirement of invasive mechanical ventilation/intubation with obesity. All-cause mortality in COVID-19 positive hospitalized patients with obesity was the secondary outcome of the study. Results: In total, 3,140,413 patients from 167 studies were included in the study. Obesity was associated with an increased risk of severe disease (RR=1.52, 95% CI 1.41-1.63, p<0.001, I2 = 97%). Similarly, high mortality was observed in obese patients (RR=1.09, 95% CI 1.02-1.16, p=0.006, I2 = 97%). In multivariate meta-regression on severity, the covariate of the female gender, pulmonary disease, diabetes, older age, cardiovascular diseases, and hypertension was found to be significant and explained R2 = 40% of the between-study heterogeneity for severity. The aforementioned covariates were found to be significant for mortality as well, and these covariates collectively explained R2 = 50% of the between-study variability for mortality. Conclusions: Our findings suggest that obesity is significantly associated with increased severity and higher mortality among COVID-19 patients. Therefore, the inclusion of obesity or its surrogate body mass index in prognostic scores and improvement of guidelines for patient care management is recommended.

Unabridged Histoplasmosis Myositis: Unsolved Dissemination with Diagnostic Challenge.

Histoplasmosis occurs predominantly in immunocompromised hosts and typically presents with mild constitutional symptoms, weight loss, weakness, fatigability, hepatosplenomegaly, and lymphadenopathy. The diagnosis is generally delayed and is based upon isolating the organism in blood cultures or by identifying intracellular organisms in tissues. Disseminated Histoplasmosis is well described in HIV patients but Histoplasmosis myositis is a rare manifestation and has not been reported in seronegative patients till date. We here address a case of a pharmacologically immunosuppressed patient with extensive Histoplasmosis myositis invading almost all the skeletal muscles of body (including plantar foot muscles) with no evidence of dissemination to other organ-systems. Clinical examination and investigations co-related with infiltrative muscle disease and skeletal muscle biopsy revealed Histoplasma capsulatum. This patient illustrates a distinctive clinical presentation of fungal infection with subtle constitutional symptoms and isolated muscle weakness which added to the diagnostic challenge. Hence, differential diagnosis of fungal infection must always be considered as a cause of myopathy in any pharmacologically immunosuppressed patient.

XIAP Knockdown in Alcohol-Associated Liver Disease Models Exhibits Divergent in vitro and in vivo Phenotypes Owing to a Potential Zonal Inhibitory Role of SMAC.

Alcohol-associated liver disease (ALD) has been recognized as the most common cause of advanced liver disease worldwide, though mechanisms of pathogenesis remain incompletely understood. The X-linked inhibitor of apoptosis (XIAP) protein was originally described as an anti-apoptotic protein that directly binds and inhibits caspases-3, 7, and 9. Here, we investigated the function of XIAP in hepatocytes in vitro using gain and loss-of-function approaches. We noted an XIAP-dependent increase in caspase activation as well as increased inflammatory markers and pro-inflammatory EV release from hepatocytes in vitro. Primary hepatocytes (PMH) from Xiap Alb.Cre and Xiap loxP mice exhibited higher cell death but surprisingly, lower expression of inflammation markers. Conditioned media from these isolated Xiap deleted PMH further decrease inflammation in bone marrow-derived macrophages. Also, interestingly, when administered an ethanol plus Fas-agonist-Jo2 model and an ethanol plus CCl4 model, these animals failed to develop an exacerbated disease phenotype in vivo. Of note, neither Xiap Alb . Cre nor Xiap AAV8.Cre mice presented with aggravated liver injury, hepatocyte apoptosis, liver steatosis, or fibrosis. Since therapeutics targeting XIAP are currently in clinical trials and caspase-induced death is very important for development of ALD, we sought to explore the potential basis of this unexpected lack of effect. We utilized scRNA-seq and spatially reconstructed hepatocyte transcriptome data from human liver tissue and observed that XIAP was significantly zonated, along with its endogenous inhibitor second mitochondria-derived activator of caspases (SMAC) in periportal region. This contrasted with pericentral zonation of other IAPs including cIAP1 and Apollon as well as caspases 3, 7, and 9. Thus providing a potential explanation for compensation of the effect of Xiap deletion by other IAPs. In conclusion, our findings implicate a potential zonallydependent role for SMAC that prevented development of a phenotype in XIAP knockout mice in ALD models. Targeting SMAC may also be important in addition to current efforts of targeting XIAP in treatment of ALD.

Psychotic Symptoms in Heroin Withdrawal: A Case Report.

Opiate withdrawal-induced severe exacerbation of psychosis after the sudden withdrawal of an opiate is a known yet uncommon clinical manifestation. We present the case of opiate withdrawal-induced psychosis in a 25-year-old married male patient without any prior psychiatric history of illness, family history, or past hospitalization records. The patient presented with psychotic symptoms such as irritability, delusions of parasitosis, and auditory and visual hallucinations at the time of hospitalization. Symptoms were in a fluctuating course and were not constant throughout the day. Through this case report, our aim is to present a rare instance of heroin-withdrawal-induced psychosis and its successful treatment with antipsychotics.

Infective Endocarditis Leading to Intracranial Abscess: A Case Report and Literature Review.

Neurologic complications are a hallmark of infective endocarditis (IE). IE leading to intracranial abscess has an unfavorable prognosis. A 17-year-old boy with a past medical history of aortic valve replacement presented with fever and seizure. On examination, he had tachycardia, systolic murmur, slurred speech, meningeal signs, and right homonymous hemianopia. His laboratory analysis revealed an elevated erythrocyte sedimentation rate and C-reactive protein. The brain's magnetic resonance imaging revealed multiple ring-enhancing lesions in the frontal, occipital lobe, and occipitotemporal lobe, consistent with intracranial abscess. Transthoracic echocardiogram revealed a mobile mass adjacent to aortic value, consistent with possible infective vegetation. He was diagnosed with multiple cerebral septic emboli leading to intracranial abscess due to IE. Blood and cerebrospinal fluid culture revealed methicillin-sensitive Staphylococcus aureus growth. He was started on intravenous nafcillin and gentamycin. His condition improved gradually, and he became afebrile on hospital day four. On his recent follow-up, he was doing well.