CD8+ T-cell-mediated suppression of HIV-1 long terminal repeat-driven gene expression is not modulated by the CC chemokines RANTES, macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta.

OBJECTIVE: To assess the role of RANTES, macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta in modulation of HIV-1 long terminal repeat (LTR)-mediated gene expression and determine whether these chemokines share identity with CD8+ T-lymphocyte-derived HIV-1 LTR-suppressive factors. DESIGN: HIV-1 LTR-directed reporter gene expression is a model for transcription that is susceptible to inhibition by factors produced by CD8+ lymphocytes of HIV-1-infected individuals. The effect of recombinant chemokines on LTR-directed gene expression was examined. The ability of chemokines found to be present in CD8 supernatants to suppress HIV-1 LTR-mediated gene expression was determined by antibody inhibition assays. METHODS: The concentrations of RANTES, MIP-1 alpha and MIP-1 beta in a panel of CD8+ T-lymphocyte-derived supernatants were determined by enzyme-linked immunosorbent assay. Recombinant chemokines were added to freshly transfected (pLTR-CAT and pSV40-tat) human Jurkat T cells. Excessive polyclonal neutralizing antibodies to these chemokines were added to transfected Jurkat T cells cultured in the presence of strongly inhibitory CD8+ T-cell-derived supernatants with known chemokine concentrations. RESULTS: The concentrations of RANTES, MIP-1 alpha and MIP-1 beta in a panel of CD8+ lymphocyte-derived supernatants were found to correlate with their relative ability to suppress the LTR-mediated gene expression (r = 0.679, 0.764 and 0.48, respectively). The addition of recombinant CC chemokines had no effect over a broad range of doses on HIV-1 LTR-mediated gene expression. The CD8-suppressive effect on HIV-1 LTR-driven gene expression was not abrogated by a combination of antibodies of RANTES, MIP-1 alpha and MIP-1 beta. CONCLUSIONS: RANTES, MIP-1 alpha and MIP-1 beta do not alter HIV-1 LTR-directed gene expression at doses up to 100 ng/ml. Although present in varying concentrations in supernatants derived from CD8+ lymphocytes from HIV-positive individuals, these chemokines are not responsible for the powerful CD8-derived suppressive effect on HIV-1 LTR-mediated gene expression observed in our system.

CD8+ T cell-mediated suppression of HIV long terminal repeat-driven gene expression is not associated with improved clinical status.

OBJECTIVES: To determine the associations between the suppression of HIV-1 long terminal repeat (LTR)-mediated gene expression by CD8+ T-cell supernatants and clinical correlates of well-being, including CD4+ and CD8+ T-cell counts, beta-chemokine production and clinical stage of disease. METHODS: Culture supernatants of activated CD8+ T cells derived from a panel of HIV-1-infected subjects were assessed for their ability to suppress HIV-1 LTR-mediated chloramphenicol acetyl transferase (CAT) expression. The percentage suppression of gene expression was correlated with CD4+ and CD8+ T-cell counts and clinical stage of infection. Some individuals within this group were followed at 2-3 month intervals over time to assess the consistency of the suppression. Selected CD8+ T-cell culture supernatants of diverse suppressive ability were screened for the levels of the beta-chemokines macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta and RANTES. RESULTS: The ability of CD8+ T cells of HIV-1 infected subjects to suppress HIV-1 LTR-mediated gene expression did not show a dependence upon high CD4+ T-cell counts or on the clinical stage or duration of infection. The ability to suppress gene expression did show a relationship with higher CD8+ T-cell counts and correlated with the levels of beta-chemokines in the culture supernatants. In contrast, strong suppression was mediated by CD8+ T-cell supernatants from some subjects with very low CD8+ T-cell counts and relatively low chemokine levels. CONCLUSIONS: Although the suppression of gene expression by CD8+ T-cell culture supernatants showed statistical correlation with beta-chemokine levels and with higher CD8+ T-cell count, no correlation could be found with correlates of clinical well-being.

CD8+ T cell supernatants of HIV type 1-infected individuals have opposite effects on long terminal repeat-mediated transcription in T cells and monocytes.

CD8+ T lymphocytes of HIV-1-infected individuals can efficiently suppress HIV-1 replication in CD4+ T lymphocytes via soluble factors. We compared the effect of CD8+ T cell-derived supernatants on HIV-1 LTR-driven gene expression in T cells and monocytic cell lines. Our results demonstrate that CD8+ T cell supernatants that suppressed HIV-1 LTR-driven gene expression in Jurkat T cells significantly enhanced expression in Tat-activated U38 monocytic cells in the presence and absence of mitogenic stimulation. Examination of a panel of CD8+ T cell-derived supernatants form HIV-infected individuals demonstrated that the extent of enhancement of transcription in U38 cells was mirrored in most cases by a similar level of suppression of transcription in Jurkat T cells. In latently infected U1 cells treated with TNF-alpha, culture with CD8+ T cell supernatants markedly enhanced virus production. In addition, the percentage increase in the enhancement of HIV-1 LTR-driven CAT expression by CD8+ T cell supernatants correlated strongly (r = 0.911) with the level of p24 detected. The level of LTR-mediated gene expression in U38 cells was not influenced by rhMIP-1 alpha rhMIP-1 beta, or rhRANTES over a wide range of chemokine concentration. Treatment of CD8+ T cell supernatant with a combination of antibodies to these chemokines resulted in a further augmentation of LTR-mediated CAT expression in U38 cells. Taken together, these results demonstrate that CD8+ T cell suppressive factors may have opposite effects on HIV-1 LTR-driven gene expression and replication dependent on target cell type and further suggest that the beta-chemokines do not influence HIV-1 LTR-mediated gene expression in monocytic cells.

T cell-derived suppressive activity: evidence of autocrine noncytolytic control of HIV type 1 transcription and replication.

The ability of CD8+ T lymphocytes to suppress the transcription and replication of HIV-1 is well documented. We have demonstrated that the factor(s) responsible for the suppression of HIV-1 LTR-mediated gene expression are not the CC chemokines RANTES, MIP-1alpha, and MIP-1beta. Interestingly, these and other chemokines and cytokines are produced by both CD8+ and CD4+ T lymphocytes. On the presumption that CD4+ T lymphocytes may also be able to modulate HIV-1 expression in vitro we assessed the LTR-modulatory effects of a panel of culture supernatants derived from stimulated CD4+ T lymphocytes from HIV-positive patients and uninfected controls. Supernatants of both CD4+ and CD8+ T cells mediated a suppression of LTR-driven gene expression in Jurkat T cells and an enhancement of gene expression in U38 monocytic cells. On the basis of these results, and using a herpesvirus saimiri (HVS)-transformed CD4+ T lymphocyte clone (HVSCD4), we demonstrate that both suppressive and enhancing effects are dose dependent. Furthermore, we have shown that supernatants of both HVSCD4 and HVSCD8 cells suppress LTR-mediated gene expression and HIV-1 replication in transfected/infected T cells. In U1 monocytic cells, supernatants of both CD4+ and CD8+ lymphocytes from an HIV-1-infected individual enhanced LTR-mediated gene expression, HIV-1 replication, and TNF-alpha production. However, only these effects as induced by CD8+ T cells were sensitive to the G protein inhibitor pertussis toxin. These results indicate that factors produced by both CD4+ and CD8+ T cells exert dichotomous effects on HIV-1 gene expression and replication in T cells and monocytes.

Endovascular management of traumatic cervicothoracic arteriovenous fistula.

BACKGROUND: This study evaluated a single-centre experience with endovascular repair of traumatic arteriovenous fistula in the cervicothoracic region. METHODS: Endovascular repair of 27 traumatic cervicothoracic arteriovenous fistulas was attempted between August 1998 and December 2001. Patients with active bleeding or end-organ ischaemia were excluded. Follow-up was accomplished with clinical, duplex Doppler and arteriographic evaluation after 1 month and then every 3 months. RESULTS: Twelve patients with a major vessel injury were treated by stent-graft placement. Vessels involved were the subclavian (eight), common carotid (three) and internal carotid (one) arteries. Subclavian artery side branches were embolized in three of the eight patients. Four patients developed early type 4 endoleaks but all resolved. Treatment with stent-grafts was ultimately successful in all 12 patients. Three patients were lost to follow-up. During mean follow-up of 21 (range 3-36) months, one of the remaining patients developed a graft stenosis. Fifteen patients with minor vessel injuries were treated with arterial embolization. Vessels embolized were subclavian artery branches (four), external carotid artery and branches (seven) and vertebral arteries (four). Successful embolization was accomplished in ten of 15 patients. CONCLUSION: Endovascular therapy is a promising alternative to surgery for selected patients with cervicothoracic arteriovenous fistula.