NF-κB Modulates TNF-α Production by Alveolar Macrophages in Asymptomatic HIV-Seropositive Individuals

Abstract

Local TNF-α production in different organs may affect HIV replication and pathogenesis. Alveolar macrophages (AMs) obtained by bronchoalveolar lavage from asymptomatic HIV-seropositive and HIV-seronegative individuals did not spontaneously release TNF-α, but LPS stimulation of these cells significantly increased TNF-α production. We tested whether NF-κB affects TNF-α production by AMs using N-tosyl-l-phenylalanine chloromethylketone (TPCK) or N-benzoyl-l-tyrosine ethyl ester (BTEE), which inhibit the degradation of IκB, or tricyclodecan-9-yl-xanthogenate-potassium (D609), which inhibits phospholipase C. Alveolar macrophages were exposed to LPS alone and with the chemical protease inhibitors TPCK, BTEE, and D609. NF-κB DNA binding induced by LPS treatment of AMs was inhibited by TPCK, BTEE, and D609. These agents also inhibited TNF-α mRNA and TNF-α protein production. After 24 h, the levels of TNF-α mRNA reached equilibrium, as assessed by RT-PCR. The levels of NF-κB mRNA remained constant under all conditions. The levels of IκB-α mRNA were similar after 30, 60, and 180 min, but the IκB-β mRNA concentration was initially low and increased over time under all conditions. IκB-α and IκB-β protein production was not affected by the chemical protease inhibitors. Our data show that TNF-α production by LPS-stimulated AMs from asymptomatic HIV-seropositive and -seronegative individuals is regulated via the phospholipase C pathway and by NF-κB DNA binding activity without obvious changes in IκB-α or IκB-β protein concentrations.