Nitric pneumocytes

Using anti-digoxigenin-alkaUne phosphatase and nitroblue tetrazolium Punjabi et al. (1994) visualised inducible nitric oxide synthase mRNA in rat type II pneumocytes. iNOS mRNA was induced in A549-cells by interferon-y and interleukin-ip (Dweik et al. 1996). TNFa enhanced IFNy/IL-ip expression 4-fold, while IL-4 attenuated the IFNy/ IL-ip expression 4-fold. Addition of lipopolysac-charide did not affect IFNy/IL-ip iNOS expression. 

In a rat type II pneumocyte analogue, the L2 cell line, exposed for 6 h to a combination of interferon-y (2,000 U/ml) and tumour necrosis factor-a (500 U/ml), extracellular superoxide dismutase and inducible nitric oxide synthase transcription was upregulated (Brady et al. 1997). Transcription of both genes was linked by activation of the transcription factor nuclear factor-xB. 

Interferon-y and/or interleukin-ip or a combination of INF-y and TNF-a induced nitric oxide synthase in rat type II pneumocytes in vitro the production of nitric oxide was inhibited by 2 -monomethyl-L-arginine in a dose-dependent manner (Punjabi et al. 1994). 

Ozone inhalation (2 ppm, 3 h) caused a marked increase in spontaneous production of nitric oxide by type II cells (Punjabi et al. 1994). Cells from ozone-treated rats also produced significantly more nitric oxide in response to IFN-y alone and in combination with IL-ip or TNF-a than did cells from control rats. Northern blot analysis demonstrated that both increased spontaneous and IFN-y-induced production of nitric oxide by cells from ozone-exposed animals was due to an increase in inducible NOS mRNA expression. The promoter region for nitric oxide synthase gene contains consensus sequences for NfwB (). Treatment of type II pneumocytes from both control and ozone (2 ppm, 2 h) exposed rats with pyrrolidine dithiocarbamate, an inhibitor of NfxB activity, suppressed the ability of these cells to produce nitric oxide (Heck et al. 1996). 

Punjabi CJ, Laskin JD, Pendino KJ, GollerNL,Durham SK, LaskinDL. Production of nitric oxide by rat type II pneumocytes increased expression of inducible nitric oxide synthase following inhalation of a pulmonary irritant. Am J Respir Cell Mol Biol 1994 11 165-172. 

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