The regulation of TRPA1 expression and function by Th1 and Th2-type inflammation in human A549 lung epithelial cells

Abstract

Background Transient Receptor Potential Ankyrin 1 (TRPA1) is a cation channel that mediates pain, itch, cough, and neurogenic inflammation in response to pungent compounds such as acrolein in cigarette smoke. TRPA1 is also activated by endogenous factors and promotes inflammation in asthma models. We have recently shown that TRPA1 is upregulated by inflammatory cytokines in A549 human lung epithelial cells. Here, we explored the effects of Th1 and Th2-type inflammation on TRPA1. Methods and results TRPA1 expression and function was studied in A549 human lung epithelial cells. To induce inflammation, the cells were exposed to a combination of cytokines TNF-α and IL-1β; and to model Th1 or Th2-type responses, IFN-γ or IL-4/IL-13 was added, respectively. TRPA1 expression (measured by RT-PCR and Western blot) and function (assessed by Fluo-3AM intracellular calcium measurement) was enhanced under the influence of TNF-α + IL-1β. IFN-γ further enhanced TRPA1 expression and function, whereas IL-4 and IL-13 suppressed them. The effects of IFN-γ and IL-4 on TRPA1 expression were reversed by the Janus kinase (JAK) inhibitors baricitinib and tofacitinib, and those of IL-4 also by the STAT6 inhibitor AS1517499. The glucocorticoid dexamethasone downregulated TRPA1 expression, whereas the PDE4 inhibitor rolipram had no effect. Under all conditions, TRPA1 blockade was found to reduce the production of LCN2 and CXCL6. Conclusions TRPA1 expression and function in lung epithelial cells was upregulated under inflammatory conditions. IFN-γ further increased TRPA1 expression while IL-4 and IL-13 suppressed that in a JAK-STAT6 dependent manner which is novel. TRPA1 also modulated the expression of genes relevant to innate immunity and lung disease. We propose that the paradigm of Th1 and Th2 inflammation is a major determinant of TRPA1 expression and function, which should be considered when targeting TRPA1 for pharmacotherapy in inflammatory (lung) disease.

TRPV1 controls innate immunity during Citrobacter rodentium enteric infection

“…rodentium infection [ 43 ]. Additionally, it has been shown that the neutrophil-recruiting chemokine CXCL6 is upregulated by TRPA1 signaling [ 53 ], supporting regulation of this chemokine within the colon in a TRP channel dependent manner.…”

Calcium Signaling in Airway Epithelial Cells: Current Understanding and Implications for Inflammatory Airway Disease

“…37 TRPA1 has thus been suggested to mediate airway inflammation raising the possibility that it could be a molecular target for asthma. 38…”

Roles of airway and intestinal epithelia in responding to pathogens and maintaining tissue homeostasis

“…When activated, TRPA1 sets off signaling pathways that signal the body to impending dangers, initiating defensive measures such as the release of inflammatory mediators and neuropeptides. Additionally, TRPA1 regulates epithelial barrier integrity, modulates secretion, and coordinates protective responses to preserve the function of the epithelial barrier and safeguard against potential hazards (Brierley et al, 2009;Luostarinen et al, 2023).…”

“…These enzymes catalyze the production of reactive oxygen species (ROS), including superoxide and hydrogen peroxide, in response to microbial challenges (van der Vliet et al, 2018). Specifically, DUOX2/DUOXA2 serve as the primary hydrogen peroxide (H 2 O 2 ) producing system in the human colorectal mucosa and ileum (highest expression), releasing substantial quantities of H 2 O 2 from the epithelial layer into the gut lumen as part of the innate immune response (Macfie et al, 2014;Shu et al, 2023). The H 2 O 2 produced by epithelial cells acts as a defense mechanism, limiting microbial colonization and exhibiting toxicity against pathogens.…”

“…H 2 O 2 is toxic to pathogens and aids in crosslinking mucus, enhancing viscosity and reducing permeability to bacteria (Neḿeth et al, 2007;Carlson et al, 2018). Certain bacteria, such as Enterobacteriaceae, deploy catalase to neutralize H 2 O 2 and evade the host's immune response (Pericone et al, 2000;Macfie et al, 2014;Sommer and Bäckhed, 2015).…”