Zinc-depletion associates with tissue eosinophilia and collagen depletion in chronic rhinosinusitis.

BACKGROUND: Zinc plays an important role in many biological processes. Reduced zinc levels have been found in chronic rhinosinusitis (CRS) patients, however, its role in the pathophysiology of this disease remains unknown. This study examined zinc levels in the serum, mucus and tissue from CRS patients in relation to collagen content and eosinophil infiltration. The effect of zinc depletion on inflammatory cytokine production and collagen synthesis was assessed in vitro. METHODOLOGY: Zinc levels were determined in serum, mucus and tissue from controls, CRS with (CRSwNP) and without nasal polyps (CRSsNP) patients. Tissue zinc levels, collagen and inflammatory cell infiltration was examined using zinquin assays, immunofluorescence and histology on Tissue Micro Arrays. Cytokine expression and collagen synthesis was evaluated in zinc depleted primary human nasal epithelial cells (HNECs) and primary fibroblasts. RESULTS: CRSwNP patients showed reduced tissue zinc levels in correlation with a reduction in collagen content, and increased eosinophil numbers. Zinc depletion of HNECs and fibroblasts induced the production of pro-inflammatory cytokines and MUC5AC and reduced collagen secretion. CONCLUSIONS: These results suggest mucosal zinc depletion associates with tissue eosinophilia and collagen depletion in CRSwNP and induces pro-inflammatory cytokine expression and reduction of collagen synthesis in vitro.