Nrf2 protects against pulmonary fibrosis by regulating the lung oxidant level and Th1/Th2 balance

<p>Abstract</p> <p>Background</p> <p>Pulmonary fibrosis is a progressive and lethal disorder. Although the precise mechanisms of pulmonary fibrosis are not fully understood, oxidant/antioxidant and Th1/Th2 balances may play an important role in many of the processes of inflammation and fibrosis. The transcription factor Nrf2 acts as a critical regulator for various inflammatory and immune responses by controlling oxidative stress. We therefore investigated the protective role of Nrf2 against the development of pulmonary fibrosis.</p> <p>Methods</p> <p>To generate pulmonary fibrosis, both wild-type C57BL/6 mice and Nrf2-deficient mice of the same background were administered bleomycin intratracheally.</p> <p>Results</p> <p>The survival of Nrf2-deficient mice after bleomycin administration was significantly lower than that of wild-type mice. The degree of bleomycin-induced initial pulmonary inflammation and pulmonary fibrosis was much more severe in Nrf2-deficient mice than in wild-type mice. The expression of antioxidant enzymes and phase II detoxifying enzymes was significantly reduced in the lungs of Nrf2-deficient mice, concomitant with an elevation of lung 8-isoprostane level, compared with wild-type mice. The expression of Th2 cytokines, such as interleukin-4 and interleukin-13, was significantly elevated in the lungs of Nrf2-deficient mice with an increase in the number of Th2 cells that express GATA-binding protein 3.</p> <p>Conclusions</p> <p>The results indicated that Nrf2 protects against the development of pulmonary fibrosis by regulating the cellular redox level and lung Th1/Th2 balance. Thus, Nrf2 might be an important genetic factor in the determination of susceptibility to pulmonary fibrosis.</p

Ovine male genital duct epithelial cells differentiate in vitro and express functional CFTR and ENaC

To investigate the biology of the male genital duct epithelium, we have established cell cultures from the ovine vas deferens and epididymis epithelium. These cells develop tight junctions, high transepithelial electrical resistance, and a lumen-negative transepithelial potential difference as a sign of active transepithelial ion transport. In epididymis cultures the equivalent short-circuit current (I(sc)) averaged 20.8 ± 0.7 μA/cm2 (n = 150) and was partially inhibited by apical application of amiloride with an inhibitor concentration of 0.64 μM. In vas deferens cultures, I(sc) averaged 14.4 ± 1.1 μA/cm2 (n = 18) and was also inhibited by apical application of amiloride with a half-maximal inhibitor concentration (K(i)) of 0.68 μM. The remaining amiloride-insensitive I(sc) component in epididymis and vas deferens cells was partially inhibited by apical application of the Cl- channel blocker diphenylamine-2-carboxylic acid (1 mM). It was largely dependent on extracellular Cl- and, to a lesser extent, on extracellular HCO-3. It was further stimulated by basolateral application of forskolin (10-5 M), which increased I(sc) by 3.1 ± 0.3 μA/cm2 (n = 65) in epididymis and 0.9 ± 0.1 μA/cm2 (n = 11) in vas deferens. These findings suggest that cultured ovine vas deferens and epididymis cells absorb Na+ via amiloride-sensitive epithelial Na+ channels (ENaC) and secrete Cl- and HCO-3 via apical cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels. This interpretation is supported by RT-PCR data showing that vas deferens and epididymis cells express CFTR and ENaC mRNA