Folgueira, María Dolores

Persistent human immunodeficiency virus (HIV) infection of human monocytes and macrophages increases I kappa B alpha degradation, resulting in the activation of NF-kappa B, a key transcription factor in the regulation of the HIV long terminal repeat. The signal transduction pathways leading to NF-kappa B activation in cells of the monocytic lineage, especially those regulated by HIV infection, and their relevance in regulating viral persistence remain unknown. Both p21ras and its downstream Raf-1 kinase participate in the transduction of signals initiated from a variety of cell surface receptors and in the regulation of transcription factors. We have studied whether the Ras-Raf pathway is functional and participates in HIV-mediated NF-kappa B activation in monocytic cells. Constitutively active p21ras (v-H-Ras) activated NF- kappa B-dependent transcription and induces the nuclear translocation of a bona fide p65/p50 heterodimer by targeting I kappa B alpha. In addition, the constitutively active form of Raf (RafBXB) also increases the NF-kappa B-dependent transcriptional activity. Because of the similarity between HIV and Ras-Raf-induced NF-kappa B activation in monocytic cells, we next tested whether HIV-induced NF-kappa B activation was mediated by the Ras-Raf signal transduction pathway. Negative dominant forms of both Ras (Ras N17) and Raf (Raf 301) decreased the HIV- but not lipopolysaccharide-dependent NF-kappa B activation in U937 cells. Moreover, Raf-1 kinase activity was greater in HIV-infected than uninfected monocytic cells in in vitro kinase assays. Altogether, these results indicate that the Ras-Raf pathway is unregulated in HIV monocytic cells and participates in the virus-induced activation of NF-kappa B.

The molecular mechanisms regulating human immunodeficiency virus (HIV) persistence in a major cell reservoir such as the macrophage remain unknown. NF-kappa B is a transcription factor involved in the regulation of the HIV long terminal repeat and is selectively activated following HIV infection of human macrophages. Although little information as to what signal transduction pathways mediate NF-kappa B activation in monocytes-macrophages is available, our previous work indicated that classical protein kinase C (PKC) isoenzymes were not involved in the HIV-mediated NF-kappa B activation. In this study, we have focused on atypical PKC isoenzymes. PKC-zeta belongs to this family and is known to be an important step in NF-kappa B activation in other cell systems. Immunoblotting experiments with U937 cells demonstrate that PKC-zeta is present in these cells, and its expression can be downmodulated by antisense oligonucleotides (AO). The HIV-mediated NF-kappa B activation is selectively reduced by AO to PKC-zeta. In addition, cotransfection of a negative dominant molecule of PKC-zeta (PKC-zeta mut) with NF-kappa B-dependent reporter genes selectively inhibits the HIV- but not phorbol myristate acetate- or lipopolysaccharide-mediated activation of NF-kappa B. That PKC-zeta is specific in regulating NF-kappa B is concluded from the inability of PKC-zeta(mut) to interfere with the basal or phorbol myristate acetate-inducible CREB- or AP1-dependent transcriptional activity. Lastly, we demonstrate a selective inhibition of p24 production by HIV-infected human macrophages when treated with AO to PKC-zeta. Altogether, these results suggest that atypical PKC isoenzymes, including PKC-zeta, participate in the signal transduction pathways by which HIV infection results in the activation of NF-kappa B in human monocytic cells and macrophages.

Progressive multifocal leukoencephalopathy rarely occurs in patients with multiple myeloma. Intracranial central nervous system invasion is also an uncommon event in multiple myeloma, occurring in less than 1% of cases. We describe herein an exceptional case of coexisting progressive multifocal leukoencephalopathy and intraparenchymal central nervous system myeloma infiltration. A 73-year-old woman with relapsed multiple myeloma was treated with 15 cycles of lenalidomide and dexamethasone, but therapy had to be stopped because of a hip fracture after a fall. During hospitalization, the patient developed progressive multifocal leukoencephalopathy caused by John Cunningham virus, and a prominent intra-parenchymal CD138-positive infiltrate was detected. VDJ rearrangements of the immunoglobulin heavy chain gene and the mutational profile of plasma cells in bone marrow at the time of diagnosis and in brain biopsy after progression were analyzed by next generation sequencing, showing genetic differences between medullary and extramedullary myeloma cells. The role of long-term treatment with lenalidomide and dexamethasone in the development progressive multifocal leukoencephalopathy or intraparenchymal central nervous system myeloma infiltration remains unknown. However, our results suggest that both events may have arisen as a consequence of treatment-related immunosuppression. Thus, an appropriate clinical approach compatible with the simultaneous treatment of progressive multifocal leukoencephalopathy and multiple myeloma should be developed.