Hypoxia stimulates inflammatory and fibrotic responses from nasal-polyp derived fibroblasts

Chronic sinusitis is primarily an inflammatory disorder characterized by hyperplasia of immune cells and sinus tissue. Nasal mucosal swelling or polyps can occlude the sinus ostia, decreasing the level of oxygen available to the sinus tissue. Hypoxia in many diseases results in increased recruitment of inflammatory cells and release of cytokines. The role of hypoxia in chronic sinusitis is unknown. We hypothesized that hypoxia induces production of mediators that recruit cells into the sinus tissue and are involved in remodeling of the nasal mucosa.

We compared data from unstimulated nasal-polyp derived fibroblasts with those cultured in hypoxic (10% O2) and anoxic (0% O2) environments. Changes in mRNA expression and protein levels of cytokines and chemokines were measured along with changes in cellular proliferation.

Hypoxic conditions did not change the proliferative capacity of fibroblasts, whereas anoxia led to a 40% reduction in cellular proliferation (P < .05). Hypoxia led to increases in secretion of many cytokines including vascular endothelial growth factor and CCL11. As a marker of remodeling, procollagen and fibronectin production were significantly increased under hypoxic conditions.

Hypoxic conditions present in the sinus tissue could increase production of proinflammatory and remodeling cytokines that contribute to the inflammation observed in sinusitis. Surgical intervention may help decrease inflammation by allowing reoxygenation of the sinus cavity and decrease the hypoxic induction of cytokines and remodeling factors.