assessing-myogenic-response-vasoactivity-resistance-mesenteric

Assessing Myogenic Response and Vasoactivity In Resistance Mesenteric Arteries Using Pressure Myography

Small resistance arteries constrict and dilate respectively in response to increased or decreased intraluminal pressure; this phenomenon known as myogenic ...

University of Pittsburgh School of Medicine

Previously, we reported that azoxymethane (AOM)-induced liver injury is robustly exacerbated in M3 muscarinic receptor (M3R)-deficient mice. We used the same mouse model to test the hypothesis that selective pharmacological modulation of M3R activity regulates the liver injury response. Initial experiments confirmed that giving a selective M3R antagonist, darifenacin, to AOM-treated mice mimicked M3R gene ablation. Compared to vehicle controls, mice treated with the M3R antagonist had reduced survival and increased liver nodularity and fibrosis. We next assessed AOM-induced liver injury in mice treated with a selective M3R agonist, pilocarpine. After pilocarpine treatment, stimulation of post-M3R signaling in the liver was evidenced by ERK and AKT activation. In contrast to the damaging effects of the M3R antagonist, administering pilocarpine to AOM-treated mice significantly attenuated hepatic stellate cell activation, collagen deposition, bile ductule proliferation, and liver fibrosis and nodularity. As anticipated from these findings, livers from pilocarpine-treated mice exhibited reduced expression of key players in fibrosis (α1 collagen, α-smooth muscle actin, TGF-β1, PGDF, TGF-β1R, PGDFR) and decreased mRNA levels for molecules that regulate extracellular matrix formation (TIMP-1, TIMP-2, MMP-2, MMP-13). Cleaved caspase-3, nitrotyrosine and BrdU immunostaining provided evidence that pilocarpine treatment reduced hepatocyte apoptosis and oxidative stress, while increasing hepatocyte proliferation. Collectively, these findings identify several downstream mechanisms whereby M3R activation ameliorates toxic liver injury. These novel observations provide a proof-of-principle that selectively stimulating M3R activation to prevent or diminish liver injury is a therapeutic strategy worthy of further investigation.

Effects of modulating M3 muscarinic receptor activity on azoxymethane-induced liver injury in mice.

Serious gastrointestinal complications arising 13 years after the initiation of posttransplant immunosuppressant therapy with mycophenolate mofetil are reported.

Unusually late-onset mycophenolate mofetil-related colitis.

Nonalcoholic fatty liver disease (NALFD) is a leading cause of liver disease. Weight loss improves clinical features of NAFLD; however, maintenance of weight loss outside of investigational protocols is poor. The goals of this study were to characterize patterns and clinical predictors of long-term weight loss in ambulatory patients with NAFLD.

Weight loss in nonalcoholic Fatty liver disease patients in an ambulatory care setting is largely unsuccessful but correlates with frequency of clinic visits.

Dysregulated adipose tissue metabolism has been implicated in the pathogenesis of alcoholic liver disease in murine models. We aimed to characterize serum markers of adipose tissue metabolism and inflammation in patients with severe acute alcoholic hepatitis (AAH) and determine their utility to predict survival in severe AAH.

Stratification of risk of death in severe acute alcoholic hepatitis using a panel of adipokines and cytokines.

The role of muscarinic receptor subtypes in modulating acute liver injury is unknown. We detected M1 muscarinic receptor (M1R) expression in human and murine hepatocytes, and investigated the consequences of M1R deficiency on acute liver injury in vivo and inhibiting M1R activation on hepatocyte injury in vitro. Age-matched wild-type (WT) and M1R-deficient (Chrm1(-/-)) male mice were injected intraperitoneally with 200mg/kg acetaminophen (APAP) and euthanized 0, 2, 4, 16, 24, and 36h later. Biochemical and histological parameters indicated that liver injury peaked within 16h after APAP treatment and resolved by 24h. Compared to WT, M1R-deficient mice had reduced intrahepatic hemorrhage and hepatocyte necrosis, reflected by an attenuated rise in serum alanine aminotransferase levels. Livers of M1R-deficient mice showed reduced hepatocyte DNA fragmentation and attenuated expression of injury cytokines (Il-1α, Il-1β, Il-6, and Fasl). In all mice hepatic glutathione levels decreased after APAP injection, but they recovered more quickly in M1R-deficient mice. During the course of APAP-induced liver injury in M1R-deficient compared to WT mice, hepatic Nrf-2, Gclc, and Nqo1 expressions increased and nitrotyrosine generation decreased. APAP metabolic pathways were not altered by M1R deficiency; expression of hepatic Cyp2e1, Cyp1a2, Cyp3a11, Cyp3a13, Car, and Pxr was similar in Chrm1(-/-) and WT mice. Finally, treatment of murine AML12 hepatocytes with a novel M1R antagonist, VU0255035, attenuated H2O2-induced oxidative stress, prevented GSH depletion, and enhanced viability. We conclude that M1R modify hepatocyte responses to oxidative stress and that targeting M1R has therapeutic potential for toxic liver injury.

M1 muscarinic receptors modify oxidative stress response to acetaminophen-induced acute liver injury.

While animal studies have implicated derangements of global energy homeostasis in the pathogenesis of acute alcoholic hepatitis (AAH), the relevance of these findings to the development of human AAH remains unclear. Using global, unbiased serum metabolomics analysis, we sought to characterize alterations in metabolic pathways associated with severe AAH and identify potential biomarkers for disease prognosis.

Serum metabolomic profiling in acute alcoholic hepatitis identifies multiple dysregulated pathways.

Autotaxin (ATX) is an adipocyte-derived lysophospholipase that generates the lipid signaling molecule lysophosphatidic acid (LPA). The aim of this study was to determine the relationship between serum ATX and nonalcoholic fatty liver disease (NAFLD) in females with obesity.

Article	Year
Effects of modulating M3 muscarinic receptor activity on azoxymethane-induced liver injury in mice. Biochemical pharmacology\| PubMed ID: 23707755	2013
Unusually late-onset mycophenolate mofetil-related colitis. American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists\| PubMed ID: 25320135	2014
Weight loss in nonalcoholic Fatty liver disease patients in an ambulatory care setting is largely unsuccessful but correlates with frequency of clinic visits. PloS one\| PubMed ID: 25375228	2014
Stratification of risk of death in severe acute alcoholic hepatitis using a panel of adipokines and cytokines. Alcoholism, clinical and experimental research\| PubMed ID: 25421508	2014
M1 muscarinic receptors modify oxidative stress response to acetaminophen-induced acute liver injury. Free radical biology & medicine\| PubMed ID: 25452146	2015
Serum metabolomic profiling in acute alcoholic hepatitis identifies multiple dysregulated pathways. PloS one\| PubMed ID: 25461442	2014
Serum autotaxin is independently associated with hepatic steatosis in women with severe obesity. Obesity (Silver Spring, Md.)\| PubMed ID: 25865747	2015

Vikrant Rachakonda

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