Dong Y, et al. - In vitro tests were performed by researchers to examine the pro-inflammatory capacity of various S. epidermidis strains on human alveolar epithelial cells. At a multiplicity of infection ratio of 10 for 24 h, live bacteria of S. epidermidis RP62A strain (biofilm-positive) and ATCC 12228 strain (biofilm-negative) were used to stimulate A549 cell monolayers. MTT method was used to measure cell viability. They used RT-PCR, immunoassays and immunofluorescence to evaluate mRNA and protein expression of inflammatory mediators and toll-like receptor-2. In vitro, S. epidermidis was identified as a driver of pro-inflammatory responses in lung epithelial cells. S. epidermidis may have a different pro-inflammatory capacity between strains. Compared to biofilm-negative S. epidermidis strain, biofilm-positive S. epidermidis strain appeared to provoke more potent pulmonary pro-inflammation.