Inhibition of HIV‐1 or bacterial activation of macrophages by products of HIV‐1‐resistant human cells

Abstract

We have recently described the molecular basis of HIV-1 resistance factor (HRF)-mediated anti-viral activity in primary and transformed CD4 T cells. HRF(+) cell culture supernatants or partially purified HRF were found to incapacitate the formation of the NF-jB/DNA complex, which is indispensable for long terminal promoter-driven transcription of virus genes. In this study, we tested whether HRF might have much broader activity against other organisms whose pathogenesis is linked to NF-jB activation. Specifically, we tested the effects of HRF on the NF-jB-mediated responses of primary macrophages to HIV-1 or several bacterial antigens. We found that exposure to HRF inhibited HIV-1 expression in macrophages and also induced the production of HRF-like activity by macrophages, which prevented replication of virus in HIV-1-infected peripheral blood lymphocytes cultured in the adjacent compartment. We investigated the mechanism of this inhibition and found that HRF impeded NF-jB/ DNA binding in macrophages induced by either HIV-1 or lipopolysaccharide from several bacteria species, resulting in impaired tumor necrosis factor-alpha responses to these organisms.

The critical role of human transcriptional repressor CTCF mRNA up-regulation in the induction of anti-HIV-1 responses in CD4+ T cells

“…The first theory was particularly interesting in conjunction with our recent observations, suggesting that HRF treatment induced the production of endogenous "HRF-like" activity in human macrophages [23]. The acquisition of antiviral protection in HIV-1 target cells resulted from their initial exposure to the soluble products of HRF(+) cell line and persevered after treatment was terminated.…”

“…The "landmark" of HRF mediated antiviral activity in CD4 + T cells is the inhibition of virus transcription through the interference with the formation of NF-κB/DNA complex [10,23]. We reported previously that HRF treatments did not restrict the NF-κB nuclear translocation and the active entity in HRF(+) supernatants did not compete with NF-κB dimer for its cognate site on HIV-1 promoter.…”

“…Based on our previous observations three days exposure to HRF induced endogenous "HRF-like" resistance in these cells, and the induction of antiviral activity could be achieved through soluble molecules present in HRF(+) cell culture supernatant [23]. On average, five days from the initial exposure to HRF(+) cell culture supernatant or three days after the cessation of HRF treatment, macrophages acquired an "HRF-like" activity which could be detected in their culture supernatants by Rapid Suppression Assay -(RSA) [9].…”

DING Proteins from Phylogenetically Different Species Share High Degrees of Sequence and Structure Homology and Block Transcription of HIV-1 LTR Promoter

“…RSA was performed essentially as described before [30]. Briefly, 1G5 cells, stably transfected with an inducible luciferase gene driven by HIV-1 LTR [33], were washed in PBS, and resuspended in hybridoma medium to a concentration of 5×10 6 cells/ml.…”

“…We applied cell-based assays to probe the therapeutic efficacy of DING proteins to block the HIV-1 LTR and virus replication, and calculated the inhibitory concentration 50 (IC 50 ). Based on the previous reports showing that the human X-DING-CD4 blocked the p50/p65 NF-κB/HIV-1 LTR binding [22], [30], [31], we employed a chromatin immunoprecipitation (ChIP) assay to observe the recruitment of p50/p65 NF-κB dimer to HIV-1 LTR promoter in cells exposed to treatment by all tested DING homologues.…”