Expression analysis of mRNA of cathelicidin (LL-37) in bronchial epithelial cells infected with Mycoplasma pneumoniae, Escherichia coli and Staphylococcus aureus

Introduction: Cathelicidin LL-37 is secreted by a number of cells, including bronchial epithelial cells and also neutrophiles, monocytes, lymphocytes and keratinocytes. It plays an important role in regulating the functions of cells, including epithelial cells. It has antimicrobial and immunomodulating properties. It destroys microorganisms directly as well as by activating subsequent immunological processes. LL-37 is active against Gram-positive and Gram-negative bacteria, while the role of LL-37 in Mycoplasma pneumoniae infections has not been thoroughly investigated. Aim: The aim of the study was to evaluate the expression of mRNA of cathelicidin LL-37 in bronchial epithelial cells infected with Mycoplasma pneumoniae, Escherichia coli and Staphylococcus aureus. Materials and methods: The bronchial tumor cell lines Beas2B ATCC CRL-9609 infected with Mycoplasma pneumoniae ATCC 15531, Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213 and uninfected (spontaneous) were cultured. LL-37 mRNA expression was determined. Results: In the case of culture infected with Mycoplasma pneumoniae, a significant increased LL-37 expression was observed in 24 h compared to the spontaneous culture and the remaining infected cultures. In cultures infected with Escherichia coli and Staphylococcus aureus a significant increased expression was observed after 72 h as compared to spontaneous culture. Conclusions: The obtained results confirmed the role of cathelicidin in antimicrobial defense in infected bronchial epithelial cells. The influence of Mycoplasma pneumoniae infection on the increased expression of cathelicidin was found and a faster stimulation of LL-37 expression was observed in comparison to Escherichia coli and Staphylococcus aureus.