Otitis media (OM) is the most common childhood bacterial infection and the leading cause of hearing loss. It remains a major health problem and a substantial socioeconomic burden. S. pneumoniae (Sp) is a major gram-positive bacteria causing OM. Current vaccine has a limited impact on OM and inappropriate antibiotic use increased antibiotic-resistance. To date there have been no effective non-antibiotic therapeutic agents available for OM due to poor understanding of Sp pathogenesis. Appropriate innate immune response is critical for host defense in children. However, if uncontrolled, excessive inflammatory response often results in immunopathology and impaired function of middle ear. Thus, innate inflammatory response must be tightly controlled. However, the key regulators and the underlying mechanisms remain largely unknown. Our long-term goal is to understand the molecular mechanisms underlying the tight control of innate inflammatory & host defense response in Sp-induced OM pathogenesis and develop novel non-antibiotic therapeutics. We previously showed that MAP kinase ERK1 positively mediates pathological responses whereas deubiquitinase CYLD and phosphatase MKP-1 act as key negative regulators of pathological responses. Thus, we hypothesized that CYLD and MKP-1 may tightly regulate Sp-induced inflammation and host defense via inhibiting ERK1 by deubiquitinating and dephosphorylating it, and up-regulating CYLD and MKP-1 may represent an ideal and novel therapeutic strategy to inhibit excessive inflammation and maintain an appropriate host defense. Indeed, our preliminary studies demonstrate that CYLD and MKP-1 act as negative regulators for Sp-induced inflammation, but positive regulators for antimicrobial -defensin, likely via inhibiting ERK1; Excitingly, systemic and CPE-mediated ototopical administration of Vinpocetine, an existing drug for neurological diseases, suppressed inflammation, improved hearing loss and enhanced -defensin induction and bacterial clearance likely via up-regulating CYLD and MKP-1. Vinpocetine also inhibited inflammation and improved hearing in a well-established model of chronic OM. These exciting preliminary data have thus laid a solid foundation for us to further investigate the mechanisms underlying tight regulation of Sp-induced innate inflammatory & host defense responses and evaluate the therapeutic potential of Vinpocetine in OM.
Our specific aims are:
Aim 1. Determine how Sp-induced innate inflammatory & host defense responses are tightly controlled by inhibiting ERK1.
Aim 2. Determine how Vinpocetine inhibits Sp-induced inflammation and enhances host defense.
Aim 3. Determine the therapeutic potential of oral and ototopical administration of Vinpocetine in suppressing Sp-induced inflammation and enhancing host defense in acute and chronic OM animal models. Overall, the proposed studies will advance our understanding of molecular pathogenesis of Sp-induced OM and may lead to novel therapeutic strategy to suppress overactive inflammation, improve middle ear hearing function and enhance host defense for Sp-induced OM (Impact & Significance).
Otitis media (OM), the most common childhood bacterial infection and the leading cause of hearing loss, remains a major health problem and a substantial socioeconomic burden, accounting for 24.5 million visits and costing over $5 billion annually. Current pneumococcal vaccine has a limited impact on OM, inappropriate antibiotic use increased antibiotic-resistance, and to date there have been no effective non-antibiotic therapeutic agents available for OM due to poor understanding of its pathogenesis. The proposed studies will advance our understanding of molecular pathogenesis of Sp-induced OM and lead to new therapeutic strategy to suppress innate inflammatory response without compromising host defense for Sp-induced OM.
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