scholarly journals Role of transient receptor potential melastatin 2 in surgical inflammation and dysmotility in a mouse model of postoperative ileus

2018 ◽  
Vol 315 (1) ◽  
pp. G104-G116 ◽  
Author(s):  
Kenjiro Matsumoto ◽  
Hiroki Kawanaka ◽  
Masatoshi Hori ◽  
Kosuke Kusamori ◽  
Daichi Utsumi ◽  
...  
Keyword(s):  
Postoperative Ileus ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Inflammatory Cells ◽  
Peritoneal Macrophages ◽  
Cytokines And Chemokines ◽  
Transient Receptor Potential Melastatin ◽  
Tnf Α ◽  
Transient Receptor

In this study, we investigated the role of transient receptor potential melastatin 2 (TRPM2), a nonselective cation channel abundantly expressed in inflammatory cells such as macrophages, in the development of postoperative ileus, a complication of abdominal surgery characterized by gastrointestinal dysmotility. In wild-type mice, we found that intestinal manipulation, a maneuver that elicits symptoms typical of postoperative ileus, delays the transit of fluorescein-labeled dextran, promotes the infiltration of CD68+ macrophages, Ly6B.2+ neutrophils, and MPO+ cells into intestinal muscles, boosts expression of IL-1β, IL-6, TNF-α, iNOS, and CXCL2 in intestinal muscles and peritoneal macrophages, enhances phosphorylation of ERK and p38 MAPK in intestinal muscles, and amplifies IL-1β, IL-6, TNF-α, iNOS, and CXCL2 expression in resident and thioglycolate-elicited peritoneal macrophages following exposure to lipopolysaccharide. Remarkably, TRPM2 deficiency completely blocks or diminishes these effects. Indeed, intestinal manipulation appears to activate TRPM2 in resident muscularis macrophages and elicits release of inflammatory cytokines and chemokines, which, in turn, promote infiltration of macrophages and neutrophils into the muscle, ultimately resulting in dysmotility. NEW & NOTEWORTHY Activation of transient receptor potential melastatin 2 (TRPM2) releases inflammatory cytokines and chemokines, which, in turn, promote the infiltration of inflammatory cells and macrophages into intestinal muscles, ultimately resulting in dysmotility. Thus TRPM2 is a promising target in treating dysmotility due to postoperative ileus, a complication of abdominal surgery.

Abstract 232: Role of Transient Receptor Potential Melastatin 2 in Cardiomyocyte Apoptosis Induced by TNF-α

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Shuzhuang Li ◽  
Xuan Liu ◽  
Deqin Yu ◽  
Chong Chen ◽  
Xiaolong Chen
Keyword(s):  
Myocardial Injury ◽  
Caspase 3 ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Cardiomyocyte Apoptosis ◽  
Mechanical Trauma ◽  
Causative Role ◽  
Transient Receptor Potential Melastatin ◽  
Tnf Α ◽  
Transient Receptor

Mechanical trauma, such as that induced by motor vehicle crashes, represents a major medical and economic problem in the world. Identifying the mechanisms responsible for post-traumatic secondary myocardial injury is critical in order to reduce overall mortality and improve quality of life after trauma. We have previously demonstrated that mechanical trauma-induced overproduction of TNF-α plays a causative role in cardiomyocyte apoptosis via oxidative/nitrative stress. Transient receptor potential melastatin 2 (TRPM2) is a Ca 2+ permeable non-selective cation channel activated by oxidative stress, expressed in the cardiomyocytes. The present study attempted to identify whether TRPM2 is involved in TNF-α-induced cardiomyocyte apoptosis. Cardiomyocytes were isolated from adult male Sprague Dawley rats and cultured with TNF-α (10 ng/ml) for 12h. RT-PCR and semi-quantitative immunohistochemistry were used to quantify TRPM2 mRNA and protein levels respectively. Significant increases in TRPM2 mRNA and protein expression were observed in TNF-α-treated cardiomyocytes, suggesting that TRPM2 may contribute to TNF-α-induced cardiomyocyte apoptosis. To identify the effect of TRPM2 on TNF-α-induced cardiomyocyte apoptosis, cardiomyocytes were cultured with TNF-α or TNF-α + TRPM2 inhibitor (flufenamic acid (FFA) 100uM or clotrimazole 30uM), respectively. Exposure of cardiomyocytes to TNF-α for 12h induced significant apoptosis as determined by caspase-3 activation (1.7-fold increase vs. control, P < 0.01). In contrast, TNF-α-induced caspase-3 activity increases were significantly depressed by FFA and clotrimazole, respectively (P < 0.05). To further confirm the effect of TRPM2 on TNF-α-induced cardiomyocyte apoptosis, we tested the effects of TRPM2-specific small interfering RNA (siRNA). As a result, impressively, TNF-α-induced increases of caspase-3 activity and lysate nucleosomes were significantly reduced in TRPM2-specific siRNA-treated cardiomyocytes (P < 0.01). These results indicate that TRPM2 plays an important role in TNF-α-induced cardiomyocyte apoptosis. We propose functional inhibition of TRPM2 channels as a new therapeutic strategy for treating mechanical trauma-induced secondary myocardial injury.

scholarly journals Novel regulatory mechanism in human urinary bladder: central role of transient receptor potential melastatin 4 channels in detrusor smooth muscle function

2016 ◽  
Vol 310 (7) ◽  
pp. C600-C611 ◽  
Author(s):  
Kiril L. Hristov ◽  
Amy C. Smith ◽  
Shankar P. Parajuli ◽  
John Malysz ◽  
Eric S. Rovner ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Transient Receptor Potential ◽  
Single Cells ◽  
Receptor Potential ◽  
Detrusor Smooth Muscle ◽  
Rt Pcr ◽  
Transient Receptor Potential Melastatin ◽  
Transient Receptor ◽  
Trpm4 Channel

Transient receptor potential melastatin 4 (TRPM4) channels are Ca2+-activated nonselective cation channels that have been recently identified as regulators of detrusor smooth muscle (DSM) function in rodents. However, their expression and function in human DSM remain unexplored. We provide insights into the functional role of TRPM4 channels in human DSM under physiological conditions. We used a multidisciplinary experimental approach, including RT-PCR, Western blotting, immunohistochemistry and immunocytochemistry, patch-clamp electrophysiology, and functional studies of DSM contractility. DSM samples were obtained from patients without preoperative overactive bladder symptoms. RT-PCR detected mRNA transcripts for TRPM4 channels in human DSM whole tissue and freshly isolated single cells. Western blotting and immunohistochemistry with confocal microscopy revealed TRPM4 protein expression in human DSM. Immunocytochemistry further detected TRPM4 protein expression in DSM single cells. Patch-clamp experiments showed that 9-phenanthrol, a selective TRPM4 channel inhibitor, significantly decreased the transient inward cation currents and voltage step-induced whole cell currents in freshly isolated human DSM cells. In current-clamp mode, 9-phenanthrol hyperpolarized the human DSM cell membrane potential. Furthermore, 9-phenanthrol attenuated the spontaneous phasic, carbachol-induced and nerve-evoked contractions in human DSM isolated strips. Significant species-related differences in TRPM4 channel activity between human, rat, and guinea pig DSM were revealed, suggesting a more prominent physiological role for the TRPM4 channel in the regulation of DSM function in humans than in rodents. In conclusion, TRPM4 channels regulate human DSM excitability and contractility and are critical determinants of human urinary bladder function. Thus, TRPM4 channels could represent promising novel targets for the pharmacological or genetic control of overactive bladder.

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