Hyaluronan-Leukocyte Interactions in Asthma

Cleveland Clinic Lerner Com-Cwru, Cleveland OH

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Abstract

The overall goal of Project 2 of the Research Program is to define the essential role of the abnormal[unreadable] hyaluronan (HA)-based matrix that is synthesized by airway smooth muscle (ASM) and airway epithelial (AE)[unreadable] cells in response to pathological stimuli (viral, allergen) and that modulates asthmatic inflammation through[unreadable] interactions with inflammatory cells (monocytes/macrophages, mast cells, eosinophils). Our data show that[unreadable] cultures of ASM and AE cell cultures respond to poly(l:C) (a viral mimetic) and tunicamycin (endoplasmic[unreadable] reticulum (ER) stress) by synthesizing HA-based structures that are highly and selectively adhesive for[unreadable] binding non-activated monocytes as well as un-primed primary mast cells at 4 degrees C. At 37 degrees C, the adhesion of the monocytes is followed by a rapid (10-15 min) activation and phagocytosis of the HA matrix by a[unreadable] mechanism that includes capping of CD44, a HA-binding cell surface protein on the monocytes that is[unreadable] required for the phagocytic response. Additional strong, correlative histological data indicate that this[unreadable] process occurs in vivo in asthmatic individuals and in the aeroallergen/pathogen mouse model of asthma[unreadable] that is central to this Research Program. The same histological sections also show a strong ER stress[unreadable] response in AE cells while nearby vascular endothelial cells do not. The aims of this Project are to treat[unreadable] murine ASM cell cultures with poly(l:C) and determine: Aim 1) the mechanism by which HA is synthesized[unreadable] and incorporated into the HA-based structures; Aim 2) the mechanism by which leukocytes adhere to these[unreadable] structures; and Aim 3a) the mechanism by which monocytes cap and phagocytose the structures. Specific[unreadable] Aim 3b will determine how primary mast cells (un-primed and primed) respond to incubation at 37 degrees C after[unreadable] selective adhesion to the HA structures at 4 degrees C. Specific Aim 4 will develop a novel lift culture model for[unreadable] growing AE cells on a native basement membrane substrate under conditions that promote AE differentiation[unreadable] and determine the response of the differentiated cultures to poly(l:C) and tunicamycin. Transgenic mouse[unreadable] models (null in CD44, in L-selectin, in both, and in TSG-6) will be used in the in vitro culture models and in[unreadable] vivo in the murine aeroallergen/pathogen model to determine the contribution of these molecules in[unreadable] formation of the HA matrix and the subsequent leukocyte adhesion and activation responses. This Project[unreadable] interacts strongly with Project 1, which will determine leukocyte tyrosine nitration/oxidation parameters in[unreadable] poly(l:C) and tunicamycin treated AE cultures with and without adhered monocytes; and with Project 3,[unreadable] which will determine how eosinophils respond to interaction with the HA structures. The use of Cores B and[unreadable] C will provide human tissue, and Core D will provide mouse tissues and the aeroallergen/pathogen model in[unreadable] the null mice.