The contribution of peroxynitrite generation in HIV replication in human primary macrophages

Background: Monocytes/Macrophages (M/M) play a pivotal role as a source of virus during the whole course of HIV-I infection. Enhanced oxidative stress is involved in the pathogenesis of HIV-I infection. HIV-I regulatory proteins induce a reduction of the expression and the activity of MnSOD, the mitochondrial isoform leading to a sustained generation of superoxide anions and peroxynitrite that represent important mediators of HIV-1 replication in M/M. MnTBAP (Mn(III) tetrakis(4-benzoic acid) porphrin chloride), a synthetic peroxynitrite decomposition catalyst, reduced oxidative stress subsequent to peroxynitrite generation. Results: Virus production was assessed by p24 ELISA, western blot, and electron microscopy during treatment with MnTBAP. MnTBAP treatment showed a reduction of HIV-I replication in both acutely and chronically infected M/M: 99% and 90% inhibition of p24 released in supernatants compared to controls, respectively. Maturation of p55 and p24 was strongly inhibited by MnTBAP in both acutely and chronically infected M/M. EC(50) and EC(90) are 3.7 (+/- 0.05) mu M and 19.5 (+/- 0.5) mu M, in acutely infected M/M; 6.3 (+/- 0.003) mu M and 30 (+/- 0.6) mu M, in chronically infected M/M. In acutely infected peripheral blood limphocytes (PBL), EC(50) and EC(90) are 7.4 (+/- 0.06)mu M and of 21.3 (+/- 0.6)mu M, respectively. Treatment of acutely-infected M/M with MnTBAP inhibited the elevated levels of malonildialdehyde (MDA) together with the nitrotyrosine staining observed during HIV-I replication. MnTBAP strongly reduced HIV-I particles in infected M/M, as shown by electron microscopy. Moreover, in presence of MnTBAP, HIV-I infectivity was reduced of about 1 log compared to control. Conclusion: Results support the role of superoxide anions in HIV-I replication in M/ M and suggest that MnTBAP may counteract HIV-1 replication in combination with other antiretroviral treatments.