American journal of physiology. Gastrointestinal and liver physiology
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Am. J. Physiol. Gastrointest. Liver Physiol. · Mar 2015
Colon distention induces persistent visceral hypersensitivity by mechanotranscription of pain mediators in colonic smooth muscle cells.
Abdominal pain and distention are major complaints in irritable bowel syndrome. Abdominal distention is mainly attributed to intraluminal retention of gas or solid contents, which may cause mechanical stress to the gut wall. Visceral hypersensitivity (VHS) may account for abdominal pain. ⋯ Patch-clamp experiments showed that the excitability of colon projecting sensory neurons in the dorsal root ganglia was markedly augmented, 24 h after lumen distention. Administration of COX-2 inhibitor NS-398 partially but significantly attenuated distention-induced VHS. In conclusion, tonic lumen distention upregulates expression of COX-2 in colonic SMC, and COX-2 contributes to persistent VHS.
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Am. J. Physiol. Gastrointest. Liver Physiol. · Feb 2015
Cytotoxic T lymphocytes and natural killer cells display impaired cytotoxic functions and reduced activation in patients with alcoholic hepatitis.
The dynamics and role of cytotoxic T lymphocytes (CTLs), natural killer (NK) cells, and NKT cells in the life-threatening inflammatory disease alcoholic hepatitis is largely unknown. These cells directly kill infected and damaged cells through, e.g., degranulation and interferon-γ (IFNγ) production, but cause tissue damage if overactivated. They also assist tissue repair via IL-22 production. ⋯ This exploratory study for the first time showed impaired cellular cytotoxicity and activation in alcoholic hepatitis. This is unlikely to cause hepatocyte death but may contribute toward the severe immune incompetence. The results warrant detailed and mechanistic studies.
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Am. J. Physiol. Gastrointest. Liver Physiol. · Dec 2014
Activation of the umami taste receptor (T1R1/T1R3) initiates the peristaltic reflex and pellet propulsion in the distal colon.
Intraluminal nutrients in the gut affect the peristaltic reflex, although the mechanism is not well defined. Recent evidence supports the presence of taste receptors and their signaling components in enteroendocrine cells, although their function is unclear. This study aimed to determine if nutrients modify colonic motility through activation of taste receptors. ⋯ Propulsion was also increased by l-cysteine, but not l-tryptophan, supporting a role of T1R1/T1R3 receptors. We conclude that T1R1/T1R3 activation by luminal MSG or l-cysteine elicits a peristaltic reflex and CGRP release and increases the velocity of pellet propulsion in distal colon. This mechanism may explain how nutrients regulate colonic propulsion.
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Am. J. Physiol. Gastrointest. Liver Physiol. · Nov 2014
Human thrombin-derived host defense peptides inhibit neutrophil recruitment and tissue injury in severe acute pancreatitis.
Severe acute pancreatitis (AP) is characterized by leukocyte infiltration and tissue injury. Herein, we wanted to examine the potential effects of thrombin-derived host defense peptides (TDPs) in severe AP. Pancreatitis was provoked by infusion of taurocholate into the pancreatic duct or by intraperitoneal administration of l-arginine in C57BL/6 mice. ⋯ Finally, a beneficial effect of TDPs was confirmed in l-arginine-induced pancreatitis. Our novel results demonstrate that TDPs exert protective effects against pathological inflammation and tissue damage in AP. These findings suggest that TDPs might be useful in the management of patients with severe AP.
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Am. J. Physiol. Gastrointest. Liver Physiol. · Oct 2014
An alteration of the gut-liver axis drives pulmonary inflammation after intoxication and burn injury in mice.
Approximately half of all adult burn patients are intoxicated at the time of their injury and have worse clinical outcomes than those without prior alcohol exposure. This study tested the hypothesis that intoxication alters the gut-liver axis, leading to increased pulmonary inflammation mediated by burn-induced IL-6 in the liver. C57BL/6 mice were given 1.2 g/kg ethanol 30 min prior to a 15% total body surface area burn. ⋯ This mitigation of hepatic damage was associated with a 49% decline in pulmonary neutrophil infiltration (P < 0.05) and decreased alveolar wall thickening compared with matched controls. These results were reproduced by prophylactic reduction of the bacterial load in the intestines with oral antibiotics before intoxication and burn injury. Overall, these data suggest that the gut-liver axis is deranged when intoxication precedes burn injury and that limiting bacterial translocation in this setting attenuates hepatic damage and pulmonary inflammation.