OBJECTIVE:

Respiratory epithelial cells are the first natural barrier against bacteria and viruses; hence, the interactions among epithelial cells, bacteria, and viruses are associated with disease occurrence and development. The effect of co-infection by P. gingivalis and influenza A virus (IAV) on respiratory epithelial cells remains unknown. The aim of this study was to analyze in vitro cell viability and apoptosis rates in respiratory epithelial A549 cells infected with P. gingivalis or IAV alone, or a combination of both pathogens.

DESIGN:

A549 cells were first divided into a control group, a P. gingivalis group, an IAV group, and a P. gingivalis?+?IAV group, to examine cell viability and apoptosis rates, the levels of microtubule associated protein 1 light chain 3?B (LC3-II), microtubule associated protein 1 light chain 3A (LC3-I), and sequestosome 1 (P62), and the formation of autophagosomes. The autophagy inhibitor, 3-methyladenine (3MA), was used to assess autophagy and apoptosis in A549 cells infected with P. gingivalis or IAV.

RESULTS:

An MTT assay revealed that cell viability was significantly lower in the IAV group than in the P. gingivalis?+?IAV group (P?
CONCLUSION:

In vitro studies showed that infection by P. gingivalis combined with IAV temporarily inhibited apoptosis in respiratory epithelial cells, and this may be related to the initiation of autophagy.