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See detailIn vivo administration of a PKA type I inhibitor (Rp-8-Br-cAMPS) restores T-cell responses in retrovirus-infected mice
Nayjib, Btissam ULg; Zeddou, Mustapha ULg; Drion, Pierre ULg et al

in Open Immunol journal (2008), 1

Murine AIDS (MAIDS) is caused by infection with the murine leukemia retrovirus RadLV-Rs and is characterized by T-cell anergy and severe immunodeficiency with increased susceptibilty to several ... [more ▼]

Murine AIDS (MAIDS) is caused by infection with the murine leukemia retrovirus RadLV-Rs and is characterized by T-cell anergy and severe immunodeficiency with increased susceptibilty to several experimental opportunistic infections as observed in HIV infection. T cell anergy is associated with an increase of intracellular cAMP level, triggering a multistep pathway involving activation of PKA type I and resulting in inhibition of proximal TCR signaling. We have reviously demonstrated that blocking PKA type I using the selective inhibitor Rp-8-Br-cAMPS, restores T-cell function in vitro in MAIDS as well as in HIV infection. In the present report, we investigated the effect of parenteral administration of Rp-8-Br-cAMPS in mice with MAIDS. We show that the compound is not toxic and partially restores the ex vivo proliferative responses to anti-CD3 mAb, but that it has no effect on the lymphadenopathy and splenomegaly characterizing the MAIDS syndrome. [less ▲]

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See detailProstaglandin E2 induces the expression of functional inhibitory CD94/NKG2A receptors in human CD8+ T lymphocytes by a cAMP-dependent protein kinase A type I pathway.
Zeddou, Mustapha ULg; Greimers, Roland ULg; de Valensart, Nicolas et al

in Biochemical Pharmacology (2005), 70(5), 714-24

The CD94/NKG2A heterodimer is a natural killer receptor (NKR), which inhibits cell-mediated cytotoxicity upon interaction with MHC class I gene products. It is expressed by NK cells and by a small ... [more ▼]

The CD94/NKG2A heterodimer is a natural killer receptor (NKR), which inhibits cell-mediated cytotoxicity upon interaction with MHC class I gene products. It is expressed by NK cells and by a small fraction of activated T cells, predominantly of CD8+ phenotype. Abnormal upregulation of the CD94/NKG2A inhibitory NKR on cytotoxic T cells (CTLs) could be responsible for a failure of immunosurveillance in cancer or HIV infection. In an attempt to identify the mechanisms leading to inhibitory NKR upregulation on T cells, we analyzed the expression of the CD94/NKG2A heterodimer on human CTLs activated with anti-CD3 mAb in the presence of PGE2 or with 8-CPT-cAMP, an analogue of cyclic AMP. As previously described, anti-CD3 mAb-mediated activation induced the expression of CD94/NKG2A on a small fraction of CD8+ T cells. Interestingly, when low concentrations of PGE2 or 8-CPT-cAMP were present during the culture, the proportion of CD8+ T cells expressing CD94/NKG2A was two- to five-fold higher. This upregulation was partially prevented by PKA inhibitors, such as KT5720 and Rp-8-Br-cAMP (type I selective). We also report that cAMP induces upregulation of NKG2A at the mRNA level. We further demonstrated that cross-linking of CD94 on CD8+ T cells expressing the CD94/NKG2A heterodimer inhibits their cytotoxic activity in a bispecific antibody redirected lysis assay. Our findings clearly demonstrate that the PGE2/cAMP/PKA type I axis is involved in the expression of CD94/NKG2A receptor on human CD8+ T lymphocytes. [less ▲]

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See detailCyclo-oxygenase type 2-dependent prostaglandin E-2 secretion is involved in retrovirus-induced T-cell dysfunction in mice
Rahmouni, Souad ULg; Aandahl, Einar Martin; Nayjib, Btissam ULg et al

in Biochemical Journal (2004), 384(Pt 3), 469-476

MAIDS (murine AIDS) is caused by infection with the murine leukaemia retrovirus RadLV-Rs and is characterized by a severe immunodeficiency and T-cell anergy combined with a lymphoproliferative disease ... [more ▼]

MAIDS (murine AIDS) is caused by infection with the murine leukaemia retrovirus RadLV-Rs and is characterized by a severe immunodeficiency and T-cell anergy combined with a lymphoproliferative disease affecting both B- and T-cells. Hyperactivation of the cAMP-protein kinase A pathway is involved in the T-cell dysfunction of MAIDS and HIV by inhibiting T-cell activation through the T-cell receptor. In the present study, we show that MAIDS involves a strong and selective up-regulation of cyclo-oxygenase type 2 in the CD11b+ subpopulation of T- and B-cells of the lymph nodes, leading to increased levels of PGE2 (prostaglandin E2). PGE2 activates the cAMP pathway through G-protein-coupled receptors. Treatment with cyclo-oxygenase type 2 inhibitors reduces the level of PGE2 and thereby reverses the T-cell anergy, restores the T-cell immune function and ameliorates the lymphoproliferative disease. [less ▲]

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