Abstract
Cigarette smoke exposure is associated with increased risk of various diseases. Epithelial cells-mediated innate immune responses to infectious pathogens are compromised by cigarette smoke. Although many studies have established that cigarette smoke exposure affects the expression of Toll-liked receptor (TLR), it remains unknown whether the nucleotide-binding oligomerization domain-containing protein 1 (NOD1) expression is affected by cigarette smoke exposure. In the study, we investigated effects of cigarette smoke extract (CSE) on NOD1 signaling in an immortalized human oral mucosal epithelial (Leuk-1) cell line. We first found that CSE inhibited NOD1 expression in a dose-dependent manner. Moreover, CSE modulated the expression of other crucial molecules in NOD1 signaling and human β defensin (hBD) 1, 2 and 3. We found that RNA interference-induced Caspase-12 silencing increased NOD1 and phospho-NF-κB (p-NF-κB) expression and down-regulated RIP2 expression. The inhibitory effects of CSE on NOD1 signaling can be attenuated partially through Caspase-12 silencing. Intriguingly, Caspase-12 silencing abrogated inhibitory effects of CSE on hBD1, 3 expression and augmented induced effect of CSE on hBD2 expression. Caspase-12 could play a vital role in the inhibitory effects of cigarette smoke on NOD1 signaling and hBDs expression in oral mucosal epithelial cells.
Highlights
Cigarette smoke, including active smoking and passive smoking, has been implicated in many diseases, disability and death [1]
Keratinocyte Serum-Free Medium (K-SFM) for Culture of Human Keratinocytes (Keratinocyte-SFM) was purchased from GIBCO (Invitrogen, Carlsbad, CA, USA), phosphatase inhibitor cocktail purchased from Roche (Mannheim, Germany), protease inhibitor cocktail was purchased from Fermentas UAB (Vilnius, Lithuania) and protein assay reagent and an enhanced chemiluminescent (ECL) kit were purchased from Pierce (Rockford, IL, USA)
The following antibodies were used: rabbit anti-nucleotide-binding oligomerization domaincontaining protein 1 (NOD1) antibody, rabbit anti-Caspase-12 antibody, mouse anti-Receptor-interacting protein 2 (RIP2) antibody, rabbit anti-p-NF-kB (p-p65) antibody, rabbit anti-NF-kB (p65) antibody, mouse anti-hBD1 antibody, and rabbit antihBD2 antibody were purchased from Abcam (Cambridge, UK); rabbit anti-hBD3 antibody was purchased from Novus (Littleton, CO, USA); rabbit anti-GAPDH antibody was purchased from Cell Signaling (Danvers, MA, USA)
Summary
Cigarette smoke, including active smoking and passive smoking, has been implicated in many diseases, disability and death [1]. A number of specific infections have been associated closely with cigarette smoke, including community-acquired pneumonia, tuberculosis, Helicobacter pylori infections, inflammatory bowel disease, invasive fungal infections, periodontitis, and oral candidiasis. Innate immunity constitutes the first line of defense against microbe infection. The human defensins, one group of small cationic antimicrobial peptides include the a-defensins of intestinal and neutrophil origin, and the b-defensins of skin, oral mucosa and other epithelia [3]. The human b defensins (hBDs) play important roles in innate immune and adaptive immune, such as antimicrobial activity, antitumor effect, chemoattractive effect and immunomodulation [4]. HBD1, 2, and 3 represent the main group of human defensins expressed and secreted by oral mucosal epithelial cells and have been most investigated The human b defensins (hBDs) play important roles in innate immune and adaptive immune, such as antimicrobial activity, antitumor effect, chemoattractive effect and immunomodulation [4]. hBD1, 2, and 3 represent the main group of human defensins expressed and secreted by oral mucosal epithelial cells and have been most investigated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
