Intracellular replication of Inquilinus limosus in bronchial epithelial cells

Abstract

Inquilinus limosus is an emerging multi-resistant opportunistic pathogen documented mainly in cystic fibrosis patients. Infection with I. limosus is accompanied by either an acute respiratory exacerbation or a progressive loss of pulmonary function. This study examined the interaction of Inquilinus limosus with the bronquial human epithelial cell line 16HBE14o−. Almost 100% of the bacteria that attached to the bronquial cells were found internalized and located in acidic LAMP2 positive compartments. According to confocal studies combined with antibiotic protection assays, I. limosus is able to survive and eventually replicate in these compartments. I. limosus was found nontoxic to cells and did not induce neither IL-6 nor IL-8 cytokine production, a characteristic that may help the bacteria to evade host immune response. Overall, this study indicates that I. limosus displays pathogenic properties based on its ability to survive intracellularly in epithelial cells eventually leading to antibiotic failure and chronic infection.