Transient Receptor Potential Channels in Intestinal Inflammation: What Is the Impact of Cigarette Smoking?

Inflammatory bowel disease (IBD) is characterized by severe gastrointestinal inflammation and results from a complex interplay between genetic and environmental factors. IBD includes two prominent subtypes: Crohn's disease (CD) and ulcerative colitis (UC). One of the main risk factors for the development of CD is cigarette smoking, while UC is rather a disease of ex-smokers. To date, many of the mechanisms underlying the immune imbalance in IBD and the involvement of cigarette smoke (CS) are incompletely understood. Transient receptor potential (TRP) proteins are non-selective cation channels that, upon activation, lead to plasma membrane depolarization and, in general, to Ca2+ influx. TRP channels of the ankyrin and vanilloid family, expressed by sensory neurons in the central and enteric nervous systems, have been extensively studied in the context of intestinal inflammation. Moreover, recent advances made on the role of non-neuronal expressed TRP channels shed light on the involvement of epithelial cells in inflammatory processes. This review focuses on how CS may impact TRP channel function in intestinal inflammation. Firstly, we discuss the current knowledge on neuronal TRP channels, known to be linked to IBD, in health, immune homeostasis and intestinal inflammation. Subsequently, we address how TRP channels are activated by CS and its components in other organ systems and also hypothesize on the potential implications for CS-mediated TRP channel activation in gut inflammation. (C) 2016 S. Karger AG, Basel