REGULATION OF SURFACTANT PROTEIN-A AND PROTEIN-B BY TNF-ALPHA AND PHORBOL ESTER INDEPENDENT OF NF-KAPPA-B

Acute lung inflammation is complicated by altered pulmonary surfactant phospholipid and protein composition. The proinflammatory cytokine tu mor necrosis factor-alpha (TNF-alpha) and the phorbol ester 12-O-tetra decanoyl phorbol-13-acetate (TPA) inhibit expression of surfactant-ass ociated proteins A and B (SP-A and SP-B), both important for normal su rfactant function. The transcription factor nuclear factor-kappa B (NF -kappa B) frequently mediates regulation of gene expression by TPA and TNF-alpha. In the present study, electrophoretic mobility shift assay s (EM-SAs) and pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF- kappa B activation, were utilized to determine the role of NF-kappa B activation in TPA and TNF-alpha inhibition of the surfactant proteins in NCI-H441 cells. Pentoxifylline (PTX), which inhibits TNF-alpha cell ular effects without preventing NF-kappa B activation, was also tested . By EMSA, TPA and TNF-alpha increased nuclear NF-kappa B binding acti vity in temporally distinct patterns. PDTC decreased TPA-and TNF-alpha -induced NF-kappa B binding activity but did not limit their inhibitio n of SP-A and SP-B mRNAs. PDTC independently decreased both SP-A and S P-B mRNAs. PTX partially reversed TNF-alpha- but not TPA-mediated inhi bition of SP-A and SP-B mRNAs without altering NF-kappa B binding. The effects of PDTC and PTX on NF-kappa B and the surfactant proteins sug gest that NF-kappa B activation does not mediate TPA or TNF-alpha inhi bition of SP-A and SP-B mRNA accumulation.