Conjunctival Goblet Cell Mucin Secretion in Inflammation and Its Resolution

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Project Summary/Abstract In response to the environment, the conjunctival goblet cells function to maintain a healthy tear film and ocular surface, and to prevent inflammatory diseases. Goblet cells secrete the mucin MUC5AC that is protective to the ocular surface. Goblet cells maintain an optimal mucous layer of the tear film by actively keeping it at normal levels in health. In disease, however, mucins can be over produced as in allergic conjunctivitis. Our laboratory concentrates on the role of goblet cell mucin production in health and in the inflammatory disease allergic conjunctivitis. The specialized pro-resolving molecules (SPMs) are produced from omega-3 fatty acids such as DHA. There is a complex and tightly regulated biology of using pro-resolution molecules to control goblet cell mucin secretion and maintain ocular surface homeostasis. In disease there is an allergy-mediated dysregulation/overproduction of mucins that contribute to the pathophysiology that SPMs resolve. Our overall goal is to investigate how SPMs are produced by the conjunctiva and act in a sex-dependent manner at a molecular level in conjunctival goblet cells to regulate mucin secretion in health and disease. We will focus on the resolvin Ds RvD1-6 that are present in tears and conjunctiva. RvD1 and RvD2 stimulate goblet cell function. In Specific Aim 1 we will focus on health and determine which RvD family members (RvD3-6) increase the intracellular [Ca2+] ([Ca2+]i), elevate cAMP, and stimulate mucin secretion in cultured conjunctival goblet cells. For this and all three aims we will evaluate if there a sex-dependent difference in response. In Specific Aim 2 we will investigate if in health RvD1 uses an autocrine circuit with a GPR32 (receptor) /DHA (precursor)/RvD1 axis to control its biosynthesis. In Specific Aim 3 we will study disease and in allergic conjunctivitis interrogate which RvD family members (RvD2-6) counter pro-inflammatory mediator stimulated goblet cell increase in [Ca2+]i and secretion, and promote resolution of AED in vivo. We will use human cultured conjunctival goblet cells, two types of SPM receptor knock out mice, and a mouse model of allergic eye disease. Intracellular [Ca2+], cAMP, MUC5AC secretion, DHA release, and RvD1 biosynthesis will be measured. In the animal model clinical symptoms, MUC5AC secretion, and leukocyte trafficking will be determined.