Research Projects

Pseudomonas aeruginosa is implicated in chronic biofilm-related infections, including wounds, urinary tracts, and cystic fibrosis, due to its capacity to adhere and invade host tissues while forming robust biofilms to evade the immune system. During pathogenesis cell adhesion molecules (CAMs), viz., cadherins, integrins, and selectins, play pivotal roles by facilitating the attachment and invasion of pathogens. Virulence factors (VFs) like ExlA, LasB of the pathogen induce cleavage of E-cadherin and VE-cadherin in epithelial and endothelial cells, respectively leading to loss of tissue integrity. Virulence properties of P. aeruginosa are regulated by three prominent quorum sensing (QS) systems, viz., Las, Rhl, and PQS. Interactions of the pathogen with CAMs and cleavage of epithelial and endothelial cadherins were earlier thought to be mediated by LasR, the master regulator of Las QS. But newer insights reveal a paradoxical phenomenon that majority of clinical P. aeruginosa lack functional LasR. Such spontaneous lasR mutations is a common “patho-adaptive” feature for long term persistence in the infected site by the virtue of biofilms. The present proposal intends to bridge the research gap of how these subsets of P. aeruginosa having impaired Las QS regulate the VFs by coordinating with other QS system and how the autoinducer molecules are involved in regulating the VFs during infection. Recent studies reveal that Rhl is the predominant QS during persistent infections, necessitating investigations into its role in cadherin cleavage and interaction with other CAMs to influence pathogenicity in lasR mutant P. aeruginosa subsets. Moreover, as biofilm is the predominant mode of survival of the pathogen in chronic infection, the differences in toxin mediated cadherin cleavage and inflammatory response patterns of host cells infected with planktonic and biofilms of P. aeruginosa are proposed to be assessed. Proper understanding of these intricate signalling cascades of clinically relevant pathogenic strains will help to develop suitable therapeutics against the chronic infections. Alveolar epithelial cell line (A549) and Human Umbilical Vein Endothelial Cells (HUVEC) will be infected with planktonic as well as biofilms of P. aeruginosa. Besides, cells will be treated with secretomes containing toxins to study their cadherins cleavages via western blot and flow cytometry. Gene expressions of the cadherins and the downstream signalling pathways upon infections will be assessed using qRT-PCR. It is expected that the proposed research work will help to assess how clinically relevant LasR mutant P. aeruginosa exploits the host system through quorum sensing signalling to facilitate cadherin cleavage for disrupting host cell adherence junctions leading to infection. Insights gained from the proposed work could aid in development of novel therapeutic strategies against the pathogen.