[Role of nitric oxide-nuclear factor kappaB signal pathway in functional expression of T lymphocytes from asthmatic...

To investigate the regulatory role of nitric oxide (NO)-nuclear factor kappaB (NF-kappaB) signal pathway in cytokine expressions, cell proliferation and apoptosis of T lymphocytes from asthmatic patients.

We observed the expressions and secretions of IL-4, IL-5 and IFNgamma from T lymphocytes and measured the proliferation and apoptosis of these cells by using in situ hybridization, electrophoresis mobility shift assay (EMSA), immunofluorescence, flow cytometry, two antibodies sandwich enzyme linked immuno-sorbent assay and MTT, and by administering NO donor sodium nitroprusside (SNP) and NF-kappaB inhibitor pyrrolidine dithio-carbamic acid (PTDC).

(1) The mRNA expression and protein secretion of IL-4 and IL-5 by, as well as the proliferation rate of T lymphocytes from asthmatic patients were augmented, while the mRNA expression and protein secretion of IFNgamma by, as well as the apoptosis rate of T lymphocytes from asthmatic patients were decrease as compared with the values of the control groups (P < 0.05). (2) Low dose of SNP (10 micromol/L) up-regulated the expression of these three cytokines, promoted the proliferation rate and suppressed the apoptosis rate of T lymphocytes. However, middle or high dose of SNP (100 micromol/L, 1 mmol/L, 10 mmol/L) dose-dependently down-regulated cytokine expressions and cell proliferation rate and promoted apoptosis rate. (3) PDTC inhibited the higher expressions of IL-5 and IFNgamma induced by 10 micromol/L SNP and strengthened the inhibitory effect of 1 mmol/L SNP on the expressions of IL-5 and IFNgamma. At the same time, PDTC weakened the promoting effect of 10 micromol/L SNP and strengthened the inhibitory effect of 1 mmol/L SNP on the proliferation of T lymphocytes. (4) The percentage of NF-kappaB-activated cells and NF-kappaB activity were significantly increased in T lymphocytes treated with low dose of SNP (P < 0.05); whereas these parameters were decreased in cells treated with middle or high dose of SNP (P < 0.05).

The hyper-expression of inflammatory cytokines and the increased proliferation and decreased apoptosis of T lymphocytes from asthmatic patients are related to the abnormal over-activation of NF-kappaB. NO has bi-phasic effects on the expressions of IL-5 and IFNgamma and on the proliferation and apoptosis of T lymphocytes from asthmatic patients via its bi-phasic regulations on the activity of NF-kappaB.