Nontypeable Haemophilus influenzae &host cell signaling

Wake Forest University Health Sciences, Winston-Salem NC

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Linked publications & trials

Abstract

The primary objectives of the proposed research are the identification of human bronchial epithelial cell proteins that are phosphorylated following infection with non-typeable Haemophilus influenzae (NTHi), and the relation of these events to the engagement of the platelet- activator factor (PAF) receptor by NTHi and the expression and release of inflammatory mediators by the host cell. Recent work by the applicant in Dr. Apicella's laboratory has shown that NTHi invade human bronchial epithelial cells by means of engagement of the platelet- activator factor indicated that NTHi infection elicits cytosolic calcium and inositol phosphate signals that are essential to invasion, and that prolonged carriage of opportunistic disease due to NTHi appears to enrich for variants expressing ChoP. Previous work has shown that PAF receptor signaling contributes significantly to the CD14-independent host cell inflammatory response, including the release of cytokines, leukotrienes, and prostaglandin signal mediators. The major hypotheses behind this grant application are that 1) the engagement of the PAF receptor by NTHi elicits a host cell signal cascade, and 2) that this cascade is involved in bacterial invasion and the initiation and potentiation of inflammation. The applicant proposes experiments to identify kinase cascades activated by NTHi infection and to test their relation to NTHi invasion of host cells and the initiation of inflammation. A wild-type NTHi clinical isolate (NTHi 2019) and a panel of isogenic strains with mutations affecting ChoP and other LOS epitopes will be utilized in infection studies to test the relation of ChoP expression and PAF receptor activation to host cell signaling And the synthesis and release of inflammatory mediators by the host cell. The study of the host cell signal events initiated by NTHi infection and any causative role in the inflammatory response is particularly significant in understanding the pathophysiology of chronic obstructive pulmonary disease (COPD), which involves long-term airway inflammation. The proposed work will allow the applicant to begin to establish an independent research career in studying the molecular and cellular pathogenesis of NTHi disease, and will provide new and significant insights in to the pathophysiology of NTHi infections.