近有許多研究指出口腔的感染可能與心血管疾病有關。牙周病菌可能是透過血流來感染血管內皮細胞而導致動脈硬化等疾病。先前本實驗室發現了一個蛋白激，稱之為ZAK。ZAK隸屬於mixed lineage kinase ( MLK )家族，功能上屬於 mitogen-activated protein kinase kinase kinase ( MAP3K )。文獻指出在人類的心臟組織中能發現ZAK基因的表現。ZAK在許多細胞中會有不同的影響，例如在肝癌細胞株中大量表現會導致細胞凋亡。另外，ZAK也能刺激H9c2心肌細胞肥大化。因為牙周病菌與ZAK皆可能會引起心血管疾病，所以本篇論文的目的便是研究牙周病菌Aggregatibacter actinomycetemcomitans ( Aa ) 對於 H9c2 心肌細胞的生物性影響，以及與ZAK之間的關係。我們利用高熱殺死的Aa菌 ( 1.5×10^7 CFU/mL ) 處理H9c2心肌細胞 ( hygro、ZAK、ZAKdn ) 24小時後進行MTT分析、西方點墨法 ( Western blot ) 以及免疫螢光分析 ( Immunofluorescence Assay ) 等試驗。結果顯示，我們發現熱殺Aa菌會導致H9c2心肌細胞死亡，而且透過ZAK的表現可以增強這個能力。此外，熱殺Aa菌與ZAK皆會增加H9c2心肌細胞的Cox-2蛋白質表現量。透過免疫螢光分析，我們觀察到熱殺Aa菌能增加H9c2心肌細胞的面積。
Recently, some studies have reported that oral local infection may be related to cardiovascular disease. Periodontal pathogens may infect vascular endothelium through blood stream and induce cardiovascular diseases such as atherosclerosis. Our laboratory identified a protein kinase gene, zak. The protein ZAK functions as mitogen-activated protein kinase kinase kinase ( MAP3K ) belonging to a mixed lineage kinase ( MLK ) family. The expressions of ZAK gene were reported to be detected in various human tissues including heart. The overexpression of ZAK gene was known to induce hypertrophic growth in cardiomyoblast cells and cell apoptosis in hepatoma cell line. It is interesting to know whether the cardiopathy resulted from periopathogenic bacterial infection is connected with ZAK effects. Therefore, the purpose of this paper is to study that biological effects of Aggregatibacter actinomycetemcomitans on H9c2 cardiomyoblast cells, and what is ZAK’s role involved in these effects. H9c2 myocardiac cells ( hygro, ZAK and ZAKdn ) were cultured with heat-killed A. actinomycetemcomitans ( 1.5×10^7 CFU/mL ) for 24 h. Then MTT assay, Western blot and Immunofluorescence Assay were performed. We found that heat-killed A. actinomycetemcomitans lead to H9c2 cardiomyoblast cells death and this effect could be enhanced through expression of ZAK. Furthermore, both heat-killed A. actinomycetemcomitans and ZAK induce the expression of Cox-2 protein. By Immunofluorescence Assay, we observed that heat-killed A. actinomycetemcomitans increased the cell size of H9c2 cardiomyoblast cells.
