Histone deacetylase inhibitors induce apoptosis with minimal viral reactivation in cells infected with Kaposi's sarcoma-associated herpesvirus.

Kaposi's sarcoma-associated herpesvirus (KSHV) latently infects tumor cells in patients with Kaposi's sarcoma and primary effusion lymphoma (PEL). The purpose of this study was to determine whether histone deacetylase inhibitors (HDAI) could induce apoptosis, with minimal viral replication, in cells latently infected with KSHV. Four HDAI (depsipeptide, suberoylanilide hydroxamic acid, MS-275, and trichostatin A) were studied in two PEL B cell lines (BCBL-1, BC-3). As expected, histone hyperacetylation was readily induced in all PEL cells exposed to HDAI. HDAI also triggered KSHV reactivation in a time- and dose-dependent manner. Flow cytometric and transmission electron microscopic studies, however, revealed that reactivation occurred in only a minor percentage (3-14%) of treated cells. Importantly, and in contrast to viral reactivation, HDAI induced apoptotic cell death in a dose-dependent manner in a large percentage (up to 90%) of KSHV-infected cells. In summary, all four HDAI tested induced histone hyperacetylation in all cells, KSHV reactivation in a minority of cells, and apoptotic cell death in a majority of cells latently infected with KSHV. These findings suggest that HDAI may be a therapeutic option for patients with KSHV-mediated diseases by rendering cells infected with KSHV susceptible to apoptosis.

Lymphatic dysfunction in transgenic mice expressing KSHV k-cyclin under the control of the VEGFR-3 promoter.

Kaposi sarcoma-associated herpesvirus (KSHV) infects endothelial cells within KS tumors, and these cells express the KSHV latent-cycle gene k-cyclin (kCYC) as well as vascular endothelial growth factor receptor 3 (VEGFR-3), a marker for lymphatic endothelium. To further understand KSHV-mediated pathogenesis, we generated transgenic mice expressing kCYC under the control of the VEGFR-3 promoter. kCYC mRNA and functional protein expression within tissue correlated with VEGFR-3 expression and were most abundantly detected within lung tissue. Clinically, most transgenic mice died within 6 months of age secondary to progressive accumulation of chylous pleural fluid. In skin, edema was detected by magnetic resonance imaging and mice demonstrated persistent erythema of the ears following trauma. Histologically, erythematous skin showed extravasation of erythrocytes and accumulation of erythrocytes within lymphatic lumens. In addition, lymphatic drainage of injected contrast dyes was markedly impaired in transgenic mice. Karyomegaly, a feature observed in kCYC-expressing cells in vitro, was detected in many tissues, and selectively occurred within lymphatic endothelial cells expressing kCYC mRNA by in situ hybridization. In summary, kCYC expression within VEGFR-3+ cells of mice causes marked impairment of lymphatic function. kCYC may contribute to the development of certain clinical and histologic features of KS, including localized edema and retention of extravasated erythrocytes within KS tumors.

Micellar paclitaxel improves severe psoriasis in a prospective phase II pilot study.

BACKGROUND: Taxanes (eg, paclitaxel) are chemotherapeutic agents that have antiproliferative, antiangiogenic, and antiinflammatory properties. OBJECTIVE: We sought to explore the safety and efficacy of paclitaxel in individuals with severe psoriasis. METHODS: An open-label, prospective, phase II pilot study was conducted at the National Institutes of Health Clinical Center, a federal government medical research facility, in Bethesda, Maryland. Twelve patients with severe psoriasis, as defined by a baseline Psoriasis Area and Severity Index (PASI) score of >or= 20), were studied. Initially, patients received 6 intravenous infusions of micellar paclitaxel, 75 mg/m(2), at 4-week intervals (stage I). Later patients received 9 intravenous infusions of micellar paclitaxel at 2-week intervals (37.5 mg/m(2) for 3 doses followed by 50 mg/m(2) for six additional doses) (stage II). The primary end point was the percent change in the PASI from week 0 to week 24 in stage I and from week 0 to week 20 in stage II. RESULTS: In stage I, all 5 patients improved (mean = 59.7% decrease in PASI, median = 59.6%, range: 40.3%-79.2%). Four of the 7 patients completed stage II and all of these patients improved (mean = 45.9% decrease in PASI, median = 45.0%, range: 14.6%-79.1%). Micellar paclitaxel was well tolerated by most patients. CONCLUSIONS: Micellar paclitaxel demonstrates therapeutic activity in patients with severe psoriasis.

R5 HIV productively infects Langerhans cells, and infection levels are regulated by compound CCR5 polymorphisms.

Langerhans cells (LCs) are suspected to be initial targets for HIV after sexual exposure (by becoming infected or by capturing virus). Here, productive R5 HIV infection of LC ex vivo and LC-mediated transmission of virus to CD4+ T cells were both found to depend on CCR5. By contrast, infection of monocyte-derived dendritic cells and transfer of infection from monocyte-derived dendritic cells to CD4+ T cells were mediated by CCR5-dependent as well as DC-specific ICAM-3-grabbing nonintegrin-dependent pathways. Furthermore, in 62 healthy individuals, R5 HIV infection levels in LCs ex vivo were associated with CCR5 genotype. Specifically, genotyping for ORF Delta 32 revealed that LCs isolated from ORF Delta 32/wt individuals were significantly less susceptible to HIV when compared with LCs isolated from ORFwt/wt individuals (P = 0.016). Strikingly, further genetic analyses of the A-2459G CCR5 promoter polymorphism in ORF Delta 32/wt heterozygous individuals revealed that LCs isolated from -2459A/G + ORF Delta 32/wt individuals were markedly less susceptible to HIV than were LCs from -2459A/A + ORF Delta 32/wt individuals (P = 0.012). Interestingly, these genetic susceptibility data in LCs parallel those of genetic susceptibility studies performed in cohorts of HIV-infected individuals. Thus, we suggest that CCR5-mediated infection of LCs, and not capture of virus by LCs, provides a biologic basis for understanding certain aspects of host genetic susceptibility to initial HIV infection.

Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen prolongs the life span of primary human umbilical vein endothelial cells.

Tumor spindle cells in all clinical types of Kaposi's sarcoma (KS) are infected with Kaposi's sarcoma-associated herpesvirus (KSHV). Although KSHV contains more than 80 genes, only a few are expressed in tumor spindle cells, including latency-associated nuclear antigen (LANA) and k-cyclin (kCYC). To assess the oncogenic potential of LANA and kCYC, primary human umbilical vein endothelial cells (HUVEC) and murine NIH 3T3 cells were stably transduced by using recombinant retroviruses expressing these genes or the known viral oncogene simian virus 40 large T antigen (LTAg). Interestingly, LANA-transduced HUVEC proliferated faster and demonstrated a greatly prolonged life span (mean +/- standard deviation, 38.3 +/- 11.0 passages) than untransduced cells and vector-transduced cells (<20 passages). By contrast, kCYC-transduced HUVEC did not proliferate faster or live longer than control cells. LANA- and kCYC-transduced HUVEC, but not LTAg-transduced HUVEC, retained the ability to form normal vessel-like structures in an in vitro model of angiogenesis. In cellular assays of transformation, LANA- and kCYC-transduced NIH 3T3 cells demonstrated minimal or no anchorage-independent growth in soft agar and no tumorigenicity when injected into nude mice, unlike LTAg-transduced NIH 3T3 cells. Lastly, gene expression profiling revealed down-regulation, or silencing, of a number of genes within LANA-transduced HUVEC. Taken together, these results suggest that KSHV LANA is capable of inducing prolonged life span, but not transformation, in primary human cells. These findings may explain why LANA-expressing spindle cells proliferate within KS tumors, yet most often do not demonstrate biologic characteristics of transformation or true malignant conversion.

Decreased stimulation of CD4+ T cell proliferation and IL-2 production by highly enriched populations of HIV-infected dendritic cells.

APC infection and dysfunction may contribute to the immunopathogenesis of HIV disease. In this study, we examined immunologic function of highly enriched populations of HIV-infected monocyte-derived dendritic cells (DC). Compared with uninfected DC, HIV-infected DC markedly down-regulated surface expression of CD4. HIV p24(+) DC were then enriched by negative selection of CD4(+)HIV p24(-) DC and assessed for cytokine secretion and immunologic function. Although enriched populations of HIV-infected DC secreted increased IL-12p70 and decreased IL-10, these cells were poor stimulators of allogeneic CD4(+) T cell proliferation and IL-2 production. Interestingly, HIV-infected DC secreted HIV gp120 and the addition of soluble (s) CD4 (a known ligand for HIV gp120) to DC-CD4(+) T cell cocultures restored T cell proliferation in a dose-dependent manner. By contrast, addition of antiretroviral drugs did not affect CD4(+) T cell proliferation. Furthermore, recombinant HIV gp120 inhibited proliferation in uninfected cocultures of allogeneic DC and CD4(+) T cells, an effect that was also reversed by addition of sCD4. In summary, we show that HIV gp120 produced by DC infected by HIV in vitro impairs normal CD4(+) T cell function and that sCD4 completely reverses HIV gp120-mediated immunosuppression. We hypothesize that HIV-infected DC may contribute to impaired CD4(+) T cell-mediated immune responses in vivo and that agents that block this particular immunosuppression may be potential immune adjuvants in HIV-infected individuals.