Inflammasome and autophagy in macrophage-derived foam cells infected by Salmonella enterica serovar Typhimurium

• Main Authors: Tzu Yung Wang, 王子元
• Other Authors: Cheng Hsun Chiu
• Format: Others
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/85614927355105303371

碩士 === 長庚大學 === 生物醫學研究所 === 101 === The most common pathogen causing mycotic aneurysm in patients with atherosclerosis in Taiwan was non-typhoid Samlonella, such as S. Typhimurium. Within atheroma, foam cells differentiated from macrophage cells found were predominant. To characterize the immune response in foam cells after Salmonella infection, we used macrophage cell line THP-1 to generate foam cells with the treatment of oxidized low-density lipoprotein (ox-LDL). Immune responses between the two different cells with the infection of S. Typhimurium SL1344 in vitro were compared using cellular biological methods. We found that cytokines, including TNF-α, IL-8 and IL-1β, were highly expressed in THP-1 than in foam cells. In addition, the cell death and caspase-1 activation were more prominent in THP-1 than in foam cells. The results suggest that inflammasome activation after S. Typhimurium SL1344 infection was suppressed in foam cells. Moreover, we found that the ratio of LC3-II/LC3-I of THP-1 cells was less than that of foam cells after Salmonella infection, indicating that the lower inflammasome activity in foam cells was likely associated with autophagy because autophagy may down-regulate inflammasome activation as having been known before. NH4Cl, an autophagy inhibitor, was used to block the autophagy, and as a result, imflammasome activity was in turn prominent in foam cells. In conclusion, foam cells showed hypo-inflammatory response after Salmonella infection may be due to increased inflammasome degradation through the hyperactivation of autophagy.