The inflammatory responses of H9c2 cardiomyoblast cells induced by Aggregatibacter actinomycetemcomitans lipopolysaccharide

• Main Authors: Keng-Zad, 陳鏗任
• Other Authors: 林育誼
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/56759479705718707894

碩士 === 中山醫學大學 === 口腔生物暨材料科學研究所 === 99 === Many studies have reported that periodontal diseases may be associated with some types of systemic diseases, such as diabetes, osteoporosis, low birth weight of infants and cardiovascular disease. Periodontal pathogens pose an important risk for cardiovascular disease possibly through their abilities of inducing host inflammatory responses, including the production of cyclooxygenase (cox)-2, interleukin (IL)-1β, tumor necrosis factor (TNF)-α. Our laboratory recently identified a gene, zak, encoded a protein kinase belonging to a mixed lineage kinase family and functioning as mitogen-activated protein kinase kinase kinase. The expression of this protein kinas ZAK can be detected in various human tissues including heart. Expression of ZAK in cardiomyoblast causes a dramatic change in cell morphology and an increase in cell volume. Previous studies in our laboratory demonstrated that heat-killed Aggregatibacter actinomycetemocomitans (Aa) resulted in a reduction in cardiomyoblast cells survival while enhanced their expression of cyclooxygenase (COX)-2. To further identify the role of ZAK plays in the process of LPS induced inflammatory responses, three transgenic cardiomyoblast cell lines were used in this study: H9c2 cardiomyoblast ZAK (pTRE-ZAK), H9c2 cardiomyoblast hygro (pTRE-hygromycin resistance gene), and H9c2 cardiomyoblast ZAK dn (PTRE-dominant-negative ZAK). In our study, 0.1 and 1μg/mL Aa LPS actually protected group hygro cells from death and after 24 hours increased their cell number to 114% and 109% of control, respectively. With the help of ZAK, LPS increased group ZAK cell numbers to 125% and 122% of control, respectively, under the same condition. Group hygro cells incubated with Aa LPS showed decreased expressions in COX-2 and excellular TNF-α with an increased expression of excellular IL-10. On the other hand, group ZAK cells, in the presence of ZAK protein kinase, when incubated with Aa LPS showed a similar decreased expression of COX-2, with no effects on excellular expressions of TNF-α and IL-10. It is of noted that the baseline expression of COX-2 in group ZAK was much higher than that of group hygro. We concluded that the constitutive expression of ZAK caused a high expression of COX-2, while blunt the abilities of cell response to environmental harmful stimuli, such as bacterial LPS. On the contrary, cells without high titer of ZAK can response to LPS with normal inflammatory reactions.