NF-KAPPA-B TRANSCRIPTION FACTOR AND HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 (HIV-1) ACTIVATION BY METHYLENE-BLUE PHOTOSENSITIZATION

Reactive oxygen species like hydrogen peroxide (H2O2) have been shown to serve as messengers in the induction of NF-kappa B and then in the activation and replication of HIV-1 in human cells. Because singlet ox ygen (O-1(2)) is another very important reactive oxygen species whose action in transcription factor activation is totally undetermined, we started to investigate its role in both NF-kappa B and HIV-1 activatio n. For provoking unbalanced redox conditions, (1)0(2), was generated b y photosensitization using methylene blue as photosensitizer. Lymphocy tes or monocytes (ACH-2 or U1 respectively) latently infected with HIV -1 were treated by photosensitization mediated by methylene blue and t he production of reactive oxygen species was monitored through their c ytotoxic effect in infected cells. The generation of O-1(2), by methyl ene blue turns out to be very efficient in inducing NF-kappa B as a he terodimer composed of the p50 and p65 subunits. This induction appears specific since other transcription factors like AP-1 are only weakly activated by this treatment. In comparison with other inducing treatme nts such as phorbol esters or tumor necrosis factor alpha (TNF-alpha), the methylene-blue-mediated activation of NF-kappa B is slow, becomin g optimal 180 min after treatment. These kinetic data were obtained by following, on the same samples, both the emergence of NF-KB in the nu cleus and the disappearance of I kappa B-alpha in the cytoplasmic extr acts. Conjugated with the induction of this transcription factor, HIV- 1 reactivation from these latently infected cells was also observed by the measurement of reverse transcriptase activity in the cell superna tants. These data allow us to postulate that O-1(2) is a biologically important reactive oxygen species which could play a role in the estab lishment of oxidative stress conditions leading to HIV-1 activation vi a the presence of NF-kappa B in the nucleus of infected cells.