Cyclooxygenase and cytokine regulation in lung fibroblasts activated with viral versus bacterial pathogen associated molecular patterns.

Cyclooxygenase (COX) is required for prostanoid (e.g. prostaglandin PGE2) production. Constitutive COX-1 and inducible COX-2 are implicated in lung diseases, such as idiopathic pulmonary fibrosis (IPF). Using lung fibroblasts from humans and wild type, COX-1(-/-) and COX-2(-/-) mice, we investigated how COX activity modulates cell growth and inflammatory responses induced by activators of Toll-like receptors (TLRs) 1-8. In mouse tissue, PGE2 release from fresh lung was COX-1 driven, in lung in culture (24h) COX-1 and COX-2 driven, and from proliferating lung fibroblasts exclusively COX-2 driven. COX-2 limited proliferation in lung fibroblasts and both isoforms limited KC release induced by a range of TLR agonists. Less effect of COX was seen on TLR-induced IP-10 release. In human lung fibroblasts inhibition of COX with diclofenac was associated with increased release of IL-8 and IP-10. Our results may have implications for the treatment of IPF.

Effect of different interferonα2 preparations on IP10 and ET-1 release from human lung cells.

BACKGROUND: Alfa-interferons (IFNα2a, IFNα2b, 40KDa-PEGIFNα2a and 12KDa-PEGIFNα2b) are effective treatments for chronic hepatitis C infection. However, their usage has been associated with a variety of adverse events, including interstitial pneumonitis and pulmonary arterial hypertension. Although rare, these adverse events can be severe and potentially life-threatening, emphasizing the need for simple biomarkers of IFN-induced lung toxicity. METHODS: Human lung microvascular endothelial cells (HLMVEC), human pulmonary artery smooth muscle (HPASM) cells and A549 cells were grown under standard conditions and plated into 96- or 6-well plates. Cells were stimulated with various concentrations of different IFNs in hydrocortisone-free medium. After 24 and 48 hours, IP10 and ET-1 were measured by ELISA in conditioned medium. In a second set of experiments, cells were pre-treated with tumour necrosis factor-α (TNF-α) (10 ng/mL). RESULTS: IFNα2a, IFNα2b, 40KDa-PEGIFNα2a and 12KDa-PEGIFNα2b, but not IFNλ, induced IP10 (CXCL10) release and increased IP10 gene induction in HLMVEC. In addition, all four IFNα preparations induced IP10 release from HPASM cells and A549 cells pre-treated with TNFα. In each of these cell types, 40KDa-PEGIFNα2a was significantly less active than the native forms of IFNα2a, IFNα2b or 12KDa-PEGIFNα2b. Similarly, IFNα2a, IFNα2b and 12KDa-PEGIFNα2b, but not 40KDa-PEGIFNα2a, induced endothelin (ET)-1 release from HPASM cells. CONCLUSIONS: Consistent with other interstitial pulmonary diseases, both IP10 and ET1 may serve as markers to monitor IFN-induced lung toxicity in patients. In addition, both markers may also serve to help characterize the risk associated with IFNα preparations to induce lung toxicity.