Membrane microdomains regulate NLRP10- and NLRP12-dependent signalling in A549 cells challenged with cigarette smoke extract

Abstract

Chronic obstructive pulmonary disease (COPD) is predicted to become the third leading cause of death and disability worldwide by 2030; with cigarette smoking (active or passive) being one of the chief cause of its occurrence. Cigarette smoke exposure has been found to result in excessive inflammation and tissue injury, which might lead to COPD, although the exact pathophysiology of the disease remains elusive. While previous studies have demonstrated the role of membrane-bound Toll-like receptors (TLRs) in cigarette smoke (CS)-induced inflammation, scant information is available about the role of cytosolic NOD-like receptors (NLRs) in regulating CS-mediated inflammatory responses. Thus, we investigated the role of NLRP10 and NLRP12 in regulating inflammatory responses in human alveolar type II epithelial cells (A549) and human monocytic cells (THP-1) in response to a challenge with cigarette smoke extract (CSE). We observed CSE-mediated increase in caspase-1 activity; production of IL-1β and IL-18; and expression of NLRP10 and NLRP12 in A549 and THP-1 cells. Interestingly, immunofluorescence imaging results demonstrated an increase in the membrane recruitment of NLRP10 and NLRP12 proteins in CSE-challenged A549 cells. We also observed an increase in the expression of lipid raft proteins (caveolin-1, caveolin-2, and flotillin-1) and an induction of lipid raft assembly following CSE-exposure in A549 cells. Lipid rafts are cholesterol-rich membrane microdomains well known to act as harbours for signalling molecules. Here we demonstrate the recruitment of NLRP10 and NLRP12 in lipid raft entities as well as the interaction of NLRP12 with the lipid raft protein caveolin-1 in CSE-challenged A549 cells. Furthermore, enrichment of lipid raft entities with poly-unsaturated fatty acids (PUFA) rescued A549 cells from CSE-mediated membrane recruitment of NLRP10 and NLRP12, and also from inflammatory responses and inflammasome activation. Enrichment of membrane microdomains with PUFA was able to reverse filipin (chemical agent used for disrupting lipid rafts)-mediated enhanced inflammation in CSE-challenged A549 cells. Overall, our findings unveil a novel mechanism by identifying an important role of membrane microdomains (lipid rafts) in regulating CSE-induced inflammation and NLRP10/NLRP12-dependent signalling in A549 cells.

Caspase-1 has a critical role in blood-brain barrier injury and its inhibition contributes to multifaceted repair

“…Lipid rafts are cholesterol-rich membrane microdomains well known to act as harbors for signaling molecules. They demonstrated the recruitment of proteins from the NLRP family in lipid rafts as well as their interaction with caveolin-1 [56]. Altogether, these data may suggest that upon PX exposure an inflammasome dependent pro-inflammatory response is initiated, which in turn induces the internalization of TJ proteins via caveolae.…”

Estimation of Hub Genes and Infiltrating Immune Cells in Non-Smoking Females with Lung Adenocarcinoma by Integrated Bioinformatic Analysis

“…The correlations between these genes and smoking have also been reported. Compared with smokers, the expression level of CAV1 [ 56 ] and TOP2A [ 57 ] in non-smokers was reported to be lower, while the expression levels of TGFBR2 [ 58 ] and CAT [ 59 ] were reported to be higher in non-smokers. Taken together, although these hub genes all played essential parts in the evolution and progression of LUAD, the specific mechanisms remain not clarified, and future experimental analyses are still demanded.…”

Roles of Inflammasome in Cigarette Smoke-Related Diseases and Physiopathological Disorders: Mechanisms and Therapeutic Opportunities

“…Wang et al (27) found that cigarette smoke-induced inflammasome activation was triggered by oxidative stress injury and Ca 2+ influx in human bronchial and alveolar epithelial cells. Besides the activation of NLRP3 inflammasome, Singh et al (31) observed that increase of NLRP10 and NLRP12 proteins in human alveolar type II epithelial cells challenged by cigarette smoke extract. Furthermore, Kaur et al (32) proved that NLRP10 knockdown rescued cigarette smoke extract induced inflammatory responses in human alveolar type II epithelial cells, which might serve as an effective therapeutic target of COPD.…”

“…Futhermore, Ji et al (24) pointed out that Shufeng Jiedu Capsule (SFJDC) and oseltamivir significantly decreased NLRP3 inflammasome activation in influenza virus A-induced AECOPD disease models. Targeting NLRP10 and NLRP12 inflammasome, polyunsaturated fatty acids (PUFA) was capable of rescuing A549 cells from cigarette smoke extract (CSE)-mediated membrane recruitment of NLRP10 and NLRP12, and also from inflammatory responses (31). Finally, Supplemental Figure 1 summarized effects of cigarette smoke on NLRP3 inflammasome, and potential therapeutic strategies.…”

“…Besides the activation of NLRP3 inflammasome, Singh et al. ( 31 ) observed that increase of NLRP10 and NLRP12 proteins in human alveolar type II epithelial cells challenged by cigarette smoke extract. Furthermore, Kaur et al.…”