Background and Objective <p>Airway mucus overproduction (predominantly MUC5AC) is a well-recognized pathogenic feature in asthma, but the upstream regulatory mechanisms were enigmatic. Emerging evidence has implied the crucial role for transient receptor potential canonical channel 5 (TRPC5) in the pathogenesis of allergic diseases. Yet, the specific role of TRPC5 in asthma still remains unclear. Thus, this study was aimed to explore the functional role of TRPC5 in toluene diisocyanate (TDI)-induced mixed granulocytic asthma and to delineate the mechanisms by which TRPC5 regulate MUC5AC secretion.</p> Methods <p>Bronchoalveolar lavage fluid (BALF) and mucosal biopsy samples were collected from asthmatic subjects and control. Using a murine model of TDI-induced asthma, we gave the asthmatic mice selective TRPC5 inhibitors ML204, AC1903 or an NLRP3 inhibitor, MCC950. In vitro experiments were performed in a human airway epithelial cell line BEAS-2B.</p> Results <p>BALF levels of MUC5AC were significantly increased in the recruited asthmatic patients, as well as the levels of HMGB1, and a positive correlation was observed between the two. Expression of TRPC5 was elevated in the airway epithelium of asthmatics when compared to the control. In mice, TDI exposure raised the expression of TRPC5. Blocking TRPC5 with either ML204 or AC1903 dramatically attenuated TDI-induced airway hyperresponsiveness (AHR), airway inflammation and remodeling. Additionally, both antagonists led to inhibited activation of NLRP3 inflammasome and muc5ac secretion in TDI-exposed mice. While pharmacological inhibition of NLRP3 inflammasome suppressed TDI-induced muc5ac secretion. In vitro, TDI induced increased expression of MUC5AC, NLRP3 and TRPC5 in BEAS-2B. Silence of either <i>trpc5</i> or <i>nlrp3</i> effectively inhibited MUC5AC hypersecretion in airway epithelium induced by TDI. Besides, TRPC5 agonist (Riluzole) promoted MUC5AC overproduction in airway epithelial cells, which could be suppressed by <i>nlrp3 siRNA</i>.</p> Conclusion <p>TRPC5 contributes to TDI-induced asthma, and mediates airway epithelial muc5ac hypersecretion by partially activating NLRP3 inflammasome.</p>

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TRPC5 mediates MUC5AC secretion via NLRP3 inflammasome in toluene diisocyanate-induced mixed granulocytic asthma

  • Shuyu Chen,
  • Zhengqiang He,
  • Kai Yang,
  • Yuanyuan Liu,
  • Li Yu,
  • Linlin Zheng,
  • Wei Ma,
  • Zhou Cai,
  • Shanze Chen,
  • Lingwei Wang,
  • Rongchang Chen

摘要

Background and Objective

Airway mucus overproduction (predominantly MUC5AC) is a well-recognized pathogenic feature in asthma, but the upstream regulatory mechanisms were enigmatic. Emerging evidence has implied the crucial role for transient receptor potential canonical channel 5 (TRPC5) in the pathogenesis of allergic diseases. Yet, the specific role of TRPC5 in asthma still remains unclear. Thus, this study was aimed to explore the functional role of TRPC5 in toluene diisocyanate (TDI)-induced mixed granulocytic asthma and to delineate the mechanisms by which TRPC5 regulate MUC5AC secretion.

Methods

Bronchoalveolar lavage fluid (BALF) and mucosal biopsy samples were collected from asthmatic subjects and control. Using a murine model of TDI-induced asthma, we gave the asthmatic mice selective TRPC5 inhibitors ML204, AC1903 or an NLRP3 inhibitor, MCC950. In vitro experiments were performed in a human airway epithelial cell line BEAS-2B.

Results

BALF levels of MUC5AC were significantly increased in the recruited asthmatic patients, as well as the levels of HMGB1, and a positive correlation was observed between the two. Expression of TRPC5 was elevated in the airway epithelium of asthmatics when compared to the control. In mice, TDI exposure raised the expression of TRPC5. Blocking TRPC5 with either ML204 or AC1903 dramatically attenuated TDI-induced airway hyperresponsiveness (AHR), airway inflammation and remodeling. Additionally, both antagonists led to inhibited activation of NLRP3 inflammasome and muc5ac secretion in TDI-exposed mice. While pharmacological inhibition of NLRP3 inflammasome suppressed TDI-induced muc5ac secretion. In vitro, TDI induced increased expression of MUC5AC, NLRP3 and TRPC5 in BEAS-2B. Silence of either trpc5 or nlrp3 effectively inhibited MUC5AC hypersecretion in airway epithelium induced by TDI. Besides, TRPC5 agonist (Riluzole) promoted MUC5AC overproduction in airway epithelial cells, which could be suppressed by nlrp3 siRNA.

Conclusion

TRPC5 contributes to TDI-induced asthma, and mediates airway epithelial muc5ac hypersecretion by partially activating NLRP3 inflammasome.