C Martinez

Splenic B lymphocyte programmed cell death is prevented by nitric oxide release through mechanisms involving sustained Bcl-2 levels

Incubation of ex vivo cultured mature B cells in the presence of nitric oxide or nitric oxide-donor substances delays programmed cell death as determined by the appearance of DNA laddering in agarose gel electrophoresis or by flow-cytometry analysis of DNA. Nitric oxide also rescues B cells from antigen-induced apoptosis but fails to provide a co-stimulatory signal that converts the signal elicited by the antigen into a proliferative response. The protective effects of nitric oxide against programmed cell death can be reproduced by treatment of the cells with permeant analogues of cyclic GMP. Regarding the mechanisms by which nitric oxide prevents apoptosis in B cells, we have observed that nitric oxide release prevents the drop in the expression of the protooncogene bcl-2, both at the mRNA and protein levels, suggesting the existence of an unknown pathway that links nitric oxide signaling with Bcl-2 expression.

Suppression of HIV-1 infection in linomide-treated SCID-hu-PBL mice

Background:Proinflammatory cytokine overproduction, as well as synthesis of the inducible form of nitric oxide synthase (iNOS), are known to play a major role in HIV-1-triggered disease. AIDS patients show increased serum tumour necrosis factor (TNF)-α and interferon (IFN)-γ levels, which synergize with HIV-1-produced nitric oxide (NO) to augment viral replication. Linomide has strong immunomodulatory effects in animals and humans, yielding promising clinical benefits in several pathological disorders including septic shock and autoimmune disease, processes largely mediated by overproduction of these cytokines. In peripheral T cells, linomide also prevents apoptosis triggered by a variety of stimuli, including superantigens, dexamethasone and vaccinia virus. Design and methods:Linomide inhibits production of proinflammatory cytokines such as TNF-α, interleukin-1β and IFN-γ, as well as iNOS synthesis. The SCID-hu-PBL mouse model was used to analyse the effect of linomide on HIV-1 infection. T-cell frequency was characterized in reconstituted animals, and the frequency of infected mice and viral load of infected animals were studied. Results:Linomide promotes an increase in human CD4+ T-cell counts in the peritoneal cavity of HIV-1-infected, linomide-treated mice. Linomide also prevents human TNF-α and IFN-γ production, as well as iNOS expression and affects the viral load, promoting potent suppression of HIV-1 infectivity as detected in peritoneal cavity and spleen. Conclusions:The combination of linomides properties, namely, blockage of proinflammatory cytokine and NO production, as well as prevention of apoptosis, is of paramount interest, making linomide a potential candidate for combating HIV-1 infection or preventing some of its associated pathological manifestations.