KS Lesions Research Articles

Kaposi's sarcoma-associated herpesvirus infection prior to onset of Kaposi's sarcoma.

Kaposi's sarcoma-associated herpesvirus (KSHV), a newly discovered human gammaherpesvirus, is found in the majority of KS lesions from patients with and without AIDS. Peripheral blood mononuclear cells (PBMC) were examined for KSHV DNA to determine whether viral infection precedes onset of this neoplasm. Randomized and blinded case-control study of prospectively collected PBMC samples from ongoing cohort studies. Paired PBMC drawn before and after KS onset from 21 AIDS-KS patients were compared to paired PBMC from 23 high-risk HIV-infected homo-/bisexual patients who did not develop KS and to a single PBMC sample from 19 low-risk, HIV-infected hemophiliac patients. Extracted DNA samples were amplified by polymerase chain reaction (PCR) using two non-overlapping nested primer sets to control for potential PCR contamination. In all comparisons, patients who went on to develop KS were significantly more likely to show evidence of KSHV infection prior to onset of KS than either control group. Of PBMC samples from AIDS-KS patients drawn prior to KS, 52% were positive for KSHV DNA whereas both high- and low-risk control groups had lower rates of PBMC infection (9-13%). KSHV infection can precede KS onset by up to 21 months among AIDS-KS patients. AIDS-KS patients are significantly more likely to show evidence of KSHV infection in PBMC prior to KS onset than control HIV-infected patients. Because identical PBMC samples from cases and controls were examined blindly, these results are not caused by a bias in tissue sampling. Homo-/bisexual and hemophiliac AIDS patients who do not develop KS appear to have a low prevalence of infection. These findings indicate that KSHV infection is specifically associated with the subsequent development of KS in AIDS patients.

The epidemiology of HIV-associated Kaposiʼs sarcoma

Unraveling the mysteries associated with the etiology of KS is of tremendous public health significance. Whereas the introduction of prophylaxis has led to a decreased incidence of Pneumocystis carinii pneumonia, the incidence of KS has remained relatively stable and treatment of the HIV-infected KS patient remains a challenge. The last year has brought forth significant breakthroughs in KS research. Although KSHV has only recently been described, rapid progress is being made in understanding the role of this virus in the pathophysiology of the various forms of KS. It is too early to conclude whether KSHV is the elusive 'KS cofactor' or if all forms of KS share a common etiology, but it appears to be the single most plausible agent to be identified to date. Since all cancers are multifactorial in origin, it is likely that other host, environmental and possibly other viral cofactors could influence the risk of developing KS. The search for such cofactors must continue. Even if KSHV plays a central role, the exact mechanisms by which HIV and KSHV may interact to induce KS lesions, the tendency for KS to occur among homosexual men relative to other HIV transmission groups, and the reasons for the aggressive course of this neoplasm in HIV-infected persons remain to be determined. If a causal association can be established, KSHV could provide a model for the understanding of virus-induced neoplasia, like its cousin EBV. Although important questions regarding the specificity and temporality of KSHV and KS remain unanswered, the development and application of a sensitive serodiagnostic tool in longitudinal studies will be a crucial next step.

Cultured AIDS-related Kaposi's sarcoma (AIDS-KS) cells demonstrate impaired bioenergetic adaptation to oxidant challenge: implication for oxidant stress in AIDS-KS pathogenesis.

Despite its recognition as the most prevalent HIV associated cancer, speculation still abounds regarding the pathogenesis of AIDS-related Kaposi's sarcoma (AIDS-KS). However, it has been established that both cytokines, e.g. IL-6, and HIV-associated products, e.g., Tat, are integral in AIDS-KS cellular proliferation. Further, both experimental and clinical evidence is accumulating to link reactive oxygen intermediates (ROI) with both cytokine induction (primarily via nuclear factor-kappa B[NF-kappa B] dependent routes) as well as the subsequent cytokine, tumor necrosis factor alpha (TNF alpha) stimulation of HIV replication. Features of AIDS-KS patients, such as retention of phagocytes, presence of sustained immunostimulation, and a frequent history of KS lesions arising at traumatized sites, make oxidant stress a viable clinical factor in AIDS-KS development. Time course nucleotide profile analyses show that AIDS-KS cells have an inherent, statistically significant, biochemical deficit, even prior to oxidant stress, due to 1) a more glycolytic bioenergetic profile, resulting in lower levels of high energy phosphates (impairing capacity for glutathione [GSH] synthesis and DNA repair); 2) lower levels of NADPH (compromising the activities of GSSG reductase and peroxidase function of catalase); and 3) reduced levels of GSH (impeding both GSH peroxidase and GSH-S-transferases). Following exposure to physiologically relevant levels of H2O2, only the human microvascular endothelial cells (a putative AIDS-KS progenitor cell) responded with bioenergetic adaptations that reflected co-ordination of energy generating and cytoprotective pathways, e.g., retention of the cellular energy charge, increased NAD+, and an accentuation of the ATP, NADPH, and total adenine nucleotide differences relative to AIDS-KS cells. Also, some of the AIDS-KS strains retained intracellular GSSG subsequent to oxidant challenge, inviting the formation of deleterious protein mixed disulfides. While the results of our study address some AIDS-KS issues, they also raise an etiological question, i.e., Does the inability to tolerate oxidant stress arise in conjunction with AIDS-KS neoplastic development, or is it pre-existing in the population at risk? Regardless, use of antioxidant therapy (low risk/ potentially high benefit) in both the "at risk" population as well as in those individuals with active disease may prove a useful preventative and/or treatment modality.

Treatment of localized KS lesions

Treatment of localized KS lesions

Angiogenic properties of human immunodeficiency virus type 1 Tat protein.

Extracellular human immunodeficiency virus type 1 (HIV-1) Tat protein promotes growth of spindle cells derived from AIDS-associated Kaposi sarcoma (AIDS-KS), an angioproliferative disease very frequent in HIV-1-infected individuals. Normal vascular cells, progenitors of AIDS-KS cells, proliferate in response to Tat after exposure to inflammatory cytokines, whose levels are augmented in HIV-1-infected individuals and in KS lesions. Here we show that Tat also promotes AIDS-KS and normal vascular cells to migrate and to degrade the basement membrane and stimulates endothelial cell morphogenesis on a matrix substrate. These effects are obtained at picomolar concentrations of exogenous Tat and are promoted by the treatment of the cells with the same inflammatory cytokines stimulating expression of the receptors for Tat, the integrins alpha 5 beta 1 and alpha v beta 3. Thus, under specific circumstances, Tat has angiogenic properties. As Tat and its receptors are present in AIDS-KS lesions, these data may explain some of the mechanisms by which Tat can induce angiogenesis and cooperate in the development of AIDS-KS.

Inflammatory cytokines induce AIDS-Kaposi's sarcoma-derived spindle cells to produce and release basic fibroblast growth factor and enhance Kaposi's sarcoma-like lesion formation in nude mice.

Homosexual males often present signs of immune activation and are likely to have increased levels of inflammatory cytokines such as IL-1 beta, TNF-alpha, and IFN-gamma. These individuals develop Kaposi's sarcoma (AIDS-KS) more frequently than other HIV-1-infected groups. Our previous work demonstrated that inflammatory cytokines stimulate the growth of spindle cells derived from AIDS-KS lesions (AIDS-KS cells) and that these cells produce high levels of bFGF that mediate autocrine and paracrine (endothelial) cell growth and angiogenesis. Here we show that AIDS-KS cells constitutively produce and release bioactive bFGF in the absence of cell death, and that extracellular bFGF exist in both a soluble and a bound form; the latter can be released by treatment with trypsin, heparin, or heparinase I. Inflammatory cytokines stimulate both the synthesis and release of biologically active bFGF from KS cells and enhance their ability to induce angiogenic KS-like lesions in nude mice. Because bFGF is highly expressed in primary KS lesions, and is a mediator of KS-like lesion formation, these results suggest that the export of bFGF induced by inflammatory cytokines may play a critical role in the induction and progression of KS in HIV-1-infected homosexual men.

Pregnancy Hormones for KS

Kaposi's sarcoma, including the HIV-related form, is more common in men than women. A provocative international study proposes both an explanation and a novel treatment: the pregnancy hormone human chorionic gonadatropin (hCG). Noting that KS lesions in two African HIV-positive …

Role of Scatter Factor and The c-met Protooncogene in the Pathogenesis of Aids-Associated Kaposi's Sarcoma

Kaposi's sarcoma is a highly lethal tumor in patients with sexually acquired AIDS. A number of etiologic agents have been implicated in the development of this disease in this patient population and there is ample evidence that aberrant production of and responsiveness to KS tumor and host cell-derived cytokines plays a central role in the pathogenesis of AIDS-KS. In this review we propose that aberrant expression SF and c-met is central to the pathogenesis of KS. KS is a serious and life-threatening consequence for many patients with AIDS. Unfortunately, current therapeutic strategies for the treatment of this complex neoplasm have met with only limited success. In view of the poor survival rates for AIDS-KS patients which continue to decline at an alarming rate, it is eminently clear that a better understanding of the etiology and pathogenesis of this form of KS is needed if novel therapeutic strategies designed to successfully combat this disease are to be developed. If our hypothesis is validated, one could envision several approaches whereby the modulation of SF/c-met function or production might lead to a reduction in the incidence and severity of KS lesions. Antibody therapy directed against either SF-producing tumor cells or against the c-met receptor might decrease the incidence of new tumors by limiting their clonal expansion and lead to regression of established tumors by blocking SF-mediated tumor cell proliferation and neovascularization. It might also be possible to suppress production of SF or accessory cytokines involved in the induction SF production and thus short circuit SF/c-met growth-promoting effects. We have outlined a novel hypothesis for understanding the mechanism underlying the development of AIDS-associated KS. This is most certainly not the whole story, however. Clearly, other cytokines and alterations in natural host defenses and the immune system contribute significantly to the development of AIDS-associated KS. We believe, however, that recognition of SF/c-met as a participant in this disease is necessary if we are to more fully understand the pathogenesis of AIDS-associated KS.

Identification and culture of Kaposi's sarcoma-like spindle cells from the peripheral blood of human immunodeficiency virus-1-infected individuals and normal controls [see comments

We examined 26 patients with human immunodeficiency virus-1 (HIV-1)- associated Kaposi′s sarcoma (KS), and 76 HIV-1-infected (HIV-1+) people without KS or uninfected (HIV-1-) controls for the presence of circulating KS-like spindle cells. Adherent cells that had spindle morphology and several characteristics of spindle cells of KS lesions (KS cells) were identified in the peripheral blood mononuclear cell fraction only after culture in the presence of conditioned medium (CM) from activated lymphocytes. The peripheral blood-derived spindle cells (PBsc) expressed a variety of endothelial cell markers, such as Ulex europaeus I lectin, EN4, EN2/3, EN7/44, CD13, CD34, CD36, CD54, ELAM-1, and HLA-DR. However, they were negative for CD2, CD19, PaIE, and factor VIII-related antigen. The PBsc produced angiogenic factors as evidenced by the ability of CM from these cells to promote growth of normal vascular endothelial cells. In addition, subcutaneously injected PBsc stimulated angiogenesis in vivo in athymic nude mice. We determined that the number of PBsc grown from the peripheral blood of HIV-1+ patients with KS or at high risk to develop KS were increased by 78- fold (P = .0001) and 18-fold (P = .005), respectively, when compared with HIV-1- controls. The number of spindle cells cultured from the HIV- 1+ patients at low risk for developing KS, eg, HIV-1+ injection drug users, showed no statistical increase when compared with HIV-1- controls. The presence of increased PBsc with characteristics of KS cells in HIV-1+ KS patients or patients at high risk for developing KS gives insights into the origin of KS cells and may explain the multifocal nature of the disease. In addition, this may be useful in predicting the risk of KS development.

Kaposi's Sarcoma, Vascular Permeability, and Scientific Integrity-Reply

In Reply. —Our JAMA article, in keeping with our original correspondence with Science on April 24,1992, July 30,1992, and September 3, 1992, sought clarification of three specific issues related to the enhanced vascular permeability reported in 12-hour KS in the Science article by Dr Nakamura and colleagues 1 : (1) intense diffuse EB staining of tails in untreated but not SP-PG—treated nude mice; (2) easy extraction of extravasated tissue-bound EB-albumin complex using overnight incubation in PBS at 4°C; and (3) extraordinarily rapid extravasation of EB-albumin complex into tiny 12-hour KS lesions within 15 minutes of tail vein EB injection. Whereas heightened vascular leakiness, in addition to well-documented lymphatic dysplasia and obstruction, 2 may contribute to edema in AIDS-associated KS and angioinhibitory agents theoretically lessen such edema, the report by Nakamura et al in Science , a letter sent by Dr Gallo to Science on June 9,1992, and Science 's two tiers

Improved survival for patients with AIDS-related Kaposi's sarcoma.

We retrospectively analyzed all patients with AIDS-related Kaposi's sarcoma (AIDS-KS) seen at one large California medical center to delineate factors that may have contributed to a relative decline in survival. Potential prognostic factors were analyzed individually, using the Cox proportional hazards regression model, for their association with survival. After a stepwise Cox regression procedure was applied to those factors that showed a significant effect on survival, a subset of factors that best predicted survival was identified. We then quantified the effect of the year of diagnosis on survival using a univariate Cox model. Next, we combined the year of diagnosis with the subset of prognostic factors previously identified into the Cox model to examine survival after adjustment for the prognostic factors. Survival distribution was estimated by the Kaplan-Meier method, and the 95% confidence interval for the median survival was computed using the modified reflected method. In 688 patients, we identified four baseline variables that best predicted survival: CD4 cell number, hematocrit, number of KS lesions, and body mass index (BMI). Adjusted for these predictive factors, there was a significant improvement in survival for patients with AIDS-KS over the last 6 years. Contrary to prior reports, survival has increased for patients with AIDS-KS. The apparent increase in observed mortality is most likely due to a decline in the CD4 cell number at presentation.

Regulation of adhesion molecule expression in Kaposi's sarcoma cells.

Kaposi's sarcoma (KS) is a neoplasm with multifocal vascular lesions that is often seen in homosexual HIV-infected individuals. Infiltrates of leukocytes are characteristic components of KS lesions, and the products of leukocytes have been shown to enhance the proliferation of KS cells in vitro and most likely are crucial for the development of KS lesions in vivo. It is therefore likely that the expression of cellular adhesion molecules (CAM) is a critical determinant in the pathogenesis of KS by dictating the numbers and types of leukocytes that accumulate in areas predisposed to KS. We report that in the absence of inducers, KS cells in culture expressed low levels of ICAM-1 and undetectable VCAM-1 and E-selectin. ICAM-1, VCAM-1, and E-selectin were all induced by dsRNA (poly (I:C)), IL-1 beta, TNF-alpha, and LPS in KS cells. All of these agents increased NF-kappa B binding activity in nuclear extracts from KS cells. Neither human dermal fibroblasts nor human aortic smooth muscle cells had detectable VCAM-1 protein expression in response to conditions that led to high levels of VCAM-1 expression in KS cells. Although E-selectin expression was induced in KS cells, the peak cell surface protein levels were less than 25% the levels achieved on HUVEC or human dermal microvascular endothelial cells (HMEC). These low levels resembled the levels that were induced in HMEC immortalized with SV 40 large T Ag. These data indicate that multiple proinflammatory agents can induce NF-kappa B binding activity and can enhance ICAM-1, VCAM-1, and E-selectin expression in KS cells. The increased CAM expression enhances leukocyte binding to KS cells. Thus, the induction of CAM expression could be an early event in the development of KS by recruiting leukocytes into KS lesions, thereby providing factors that could potentiate the development of KS.

Effects of cytokines from activated immune cells on vascular cell growth and HIV-1 gene expression. Implications for AIDS-Kaposi's sarcoma pathogenesis.

Kaposi's sarcoma (KS) arises more frequently in homosexual and bisexual men than in other groups of HIV-1 infected individuals. Clinico-epidemiologic data indicate that homosexuals often are infected with multiple microbial agents and/or subjected to other antigenic stimuli, preceding or accompanying HIV-1 infection. Signs of immune activation, in fact, frequently have been detected in these individuals, and the onset of KS can precede any sign of immunodeficiency. These data have suggested that products from activated immune cells may affect the development of AIDS-KS. Here we report that conditioned media from activated or dysregulated T cells contain a variety of cytokines that promote the growth of spindle cells derived from KS lesions of AIDS patients (AIDS-KS cells) and induce normal vascular cells, potential cell progenitors of the AIDS-KS cells, to acquire features of the KS cell phenotype ("spindle" cell morphology and growth responsiveness to the mitogenic effect of extracellular HIV-1 Tat protein). The same conditioned media or cytokines promote HIV-1 gene expression and rescue defective HIV-1 proviruses, interrupting HIV-1 latency and increasing Tat production. The cellular and viral effects of cytokines are increased in an additive or synergistic manner by picomolar concentrations of extracellular Tat. These data suggest that cytokines produced by activated immune cells cooperate with HIV-1 infection in AIDS-KS pathogenesis.