Intracellular Calprotectin in the Cell-Autonomous Defense of the Oral Mucosa

University Of Minnesota, Minneapolis MN

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Abstract

DESCRIPTION (provided by applicant): Mucosal surfaces provide a biologic barrier to prevent pathogenic and commensal bacteria from encountering underiying connective tissues and continual inapproprate stimulation of systemic immune system. Forming the superficial lining ofthe mucosa, oral keratinocytes respond and contribute to the defense against pathogenic microorganisms. The long-term goal of our lab is to understand the contribution of oral keratinocytes to mucosal immunity. The focus of my PhD thesis research is the function of the antimicrobial protein (AMP) complex, calprotectin, within oral keratinocytes in response to pathogenic bacteria. In oral mucosal keratinocytes, calprotectin is constitutively expressed in the cytoplasm, unlike in epidermal and intestinal mucosal epithelial cells, which only express calprotectin during infiammation. Our preliminary data shows that oral keratinocytes use IL-1 a and calprotectin in an autonomous response to pathogenic bacteria. In brief, exogenous IL-1a up-regulates calprotectin expression and increases cellular resistance to bacterial invasion. Calprotectin overexpression by transfection in keratinocytes is inversely correlated to the expression of proinflammatory transcription factors, including. Hypoxia Inducible Factors (HIF). Thus calprotectin may have a regulatory role in maintaining the inflammatory proflle of keratinocytes. Based on these data, the central hypothesis is that intracellular calprotectin provides cell-autonomous protection to oral keratinocytes against invasive bacteria and reduces HIF-dependent inflammation. To test this hypothesis, the calprotectin-dependent cytokine and chemokine keratinocyte response to co-incubation with mucosal commensal and pathogenic bacteria will be characterized by ELISA. Second, qRT-PCR will be used to determine the affect of calprotectin expression on HIF-dependent responses to inflammatory stimuli and hypoxia. Lastiy, the role of calprotectin in IL-1 a-mediated resistance to pathogen invasion will be dilenated by knocking down calprotectin by shRNA. Together, these studies will uncover how in oral keratinocytes regulate calprotectin expression, mucosal immune responses and increase resistance to invading microorganisms.