Endoplasmic reticulum stress modulates nicotine‐induced extracellular matrix degradation in human periodontal ligament cells

Abstract

Lee S‐I, Kang K‐L, Shin S‐I, Herr Y, Lee Y‐M, Kim E‐C. Endoplasmic reticulum stress modulates nicotine‐induced extracellular matrix degradation in human periodontal ligament cells. J Periodont Res 2012; 47: 299–308. © 2012 John Wiley & Sons A/S Background and Objective: Tobacco smoking is considered to be one of the major risk factors for periodontitis. For example, about half the risk of periodontitis can be attributable to smoking in the USA. It is evident that smokers have greater bone loss, greater attachment loss and deeper periodontal pockets than nonsmoking patients. It has recently been reported that endoplasmic reticulum (ER) stress markers are upregulated in periodontitis patients; however, the direct effects of nicotine on ER stress in regard to extracellular matrix (ECM) degradation are unclear. The purpose of this study was to examine the effects of nicotine on cytotoxicity and expression of ER stress markers, selected ECM molecules and MMPs, and to identify the underlying mechanisms in human periodontal ligament cells. We also examined whether ER stress was responsible for the nicotine‐induced cytotoxicity and ECM degradation. Material and Methods: Cytotoxicity and cell death were measured by 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5 diphenyltetrazolium bromide assay and flow cytometric annexin V and propidium iodide staining. The mRNA and protein expressions of MMPs and ER markers were examined by RT‐PCR and western blot analysis. Results: Treatment with nicotine reduced cell viability and increased the proportion of annexin V‐negative, propidium iodide‐positive cells, an indication of cell death. Nicotine induced ER stress, as evidenced by survival molecules, such as phosphorylated protein kinase‐like ER‐resident kinase, phosphorylated eukaryotic initiation factor‐2α and glucose‐regulated protein‐78, and apoptotic molecules, such as CAAT/enhancer binding protein homologous protein (CHOP). Nicotine treatment led to the downregulation of ECM molecules, including collagen type I, elastin and fibronectin, and upregulation of MMPs (MMP‐1, MMP‐2, MMP‐8 and MMP‐9). Inhibition of ER stress by salubrinal and transfection of CHOP small interfering RNA attenuated the nicotine‐induced cell death, ECM degradation and production of MMPs. Salubrinal and CHOP small interfering RNA inhibited the effects of nicotine on the activation of Akt, JNK and nuclear factor‐κB. Conclusion: These results indicate that nicotine‐induced cell death is mediated by the ER stress pathway, involving ECM degradation by MMPs, in human periodontal ligament cells.

Effects of sirtuin 1 activation on nicotine and lipopolysaccharide‐induced cytotoxicity and inflammatory cytokine production in human gingival fibroblasts

“…We previously reported that induction of cellular antioxidants and phase II enzymes contribute to the cellular defense mechanisms against nicotine‐induced cytotoxicity and osteoclastic differentiation in PDLCs . In addition, we demonstrated that endoplasmic reticulum stress contributes to nicotine‐induced cell necrosis and periodontal connective tissue destruction via MAPK, phosphatidylinositol 3‐kinase (PI3K) and nuclear factor‐kappa B (NF‐κB) pathways in PDLCs .…”

HIF‐2 Inhibition Supresses Inflammatory Responses and Osteoclastic Differentiation in Human Periodontal Ligament Cells

“…The combination of nicotine and LPS induces a synergistic effect on the production of nitric oxide (NO) and PGE 2 , and increase inducible nitric oxide synthetase (iNOS) and COX‐2 expression via heme oxygenase‐1 (HO‐1) in PDLCs [Pi et al, ]. In addition, we reported that nicotine and LPS cause degradation of PDLCs or gingival fibroblasts via multiple mechanisms including Nrf‐2 [Lee et al, ], endoplasmic reticulum stress [Lee et al, ], and SIRT‐1[Park et al, ]. Furthermore, we showed that hydrogen sulfide inhibited cytotoxicity and osteoclastic differentiation and recovered osteoblastic differentiation in a nicotine‐ and LPS‐stimulated human PDLCs model [Lee et al, ].…”

Expression of Phospholipase D in Periodontitis and Its Role in the Inflammatory and Osteoclastic Response by Nicotine‐ and Lipopolysaccharide‐Stimulated Human Periodontal Ligament Cells

“…It was reported previously that nicotine upregulated the receptor activator of nuclear factor‐κB ligand (RANKL) and concomitantly inhibited osteoblastic differentiation in human periodontal ligament cells (HPDLCs) 5 . In addition, it was demonstrated that endoplasmic reticulum stress modulated nicotine‐induced cell death and extracellular matrix degradation in HPDLCs 7 …”