Clinical presentation and natural history of AIDS--related Kaposi's sarcoma

Comprehensive Analysis of the Tegument Proteins Involved in Capsid Transport and Virion Morphogenesis of Alpha, Beta and Gamma Herpesviruses

Herpesviruses are enveloped and have an amorphous protein layer surrounding the capsid, which is termed the tegument. Tegument proteins perform critical functions throughout the viral life cycle. This review provides a comprehensive and comparative analysis of the roles of specific tegument proteins in capsid transport and virion morphogenesis of selected, well-studied prototypes of each of the three subfamilies of Herpesviridae i.e., human herpesvirus-1/herpes simplex virus-1 (Alphaherpesvirinae), human herpesvirus-5/cytomegalovirus (Betaherpesvirinae) and human herpesvirus -8/Kaposi's sarcomavirus (Gammaherpesvirinae). Most of the current knowledge is based on alpha herpesviruses, in particular HSV-1. While some tegument proteins are released into the cytoplasm after virus entry, several tegument proteins remain associated with the capsid and are responsible for transport to and docking at the nucleus. After replication and capsid formation, the capsid is enveloped at the nuclear membrane, which is referred to as primary envelopment, followed by de-envelopment and release into the cytoplasm. This requires involvement of at least three tegument proteins. Subsequently, multiple interactions between tegument proteins and capsid proteins, other tegument proteins and glycoproteins are required for assembly of the virus particles and envelopment at the Golgi, with certain tegument proteins acting as the central hub for these interactions. Some redundancy in these interactions ensures appropriate morphogenesis.

Impact of valganciclovir therapy on severe IRIS-Kaposi Sarcoma mortality: An open-label, parallel, randomized controlled trial

INTRODUCTION

High HHV-8 viral load (VL) in Kaposi Sarcoma (KS) has been associated with Severe Immune Reconstitution Inflammatory Syndrome (Severe-IRIS-KS), which can occur after initiating cART, and leads to high mortality, particularly in patients with pulmonary involvement. We investigate if valganciclovir (as an anti-HHV-8 agent) initiated before cART reduces the mortality associated with Severe-IRIS-KS and the incidence of Severe-IRIS-KS.

METHODS

Open-label parallel-group randomized clinical trial in AIDS cART naïve patients with disseminated KS (DKS) as defined by at least two of the following: pulmonary, lymph-node, or gastrointestinal involvement, lymphedema, or ≥30 skin lesions. In the experimental group (EG), patients received valganciclovir 900 mg BID four weeks before cART and continued until week 48; in the control group (CG), cART was initiated on week 0. Non-severe-IRIS-KS was defined as: an increase in the number of lesions plus a decrease of ≥one log10 HIV-VL, or an increase of ≥50cells/mm3 or ≥2-fold in baseline CD4+cells. Severe-IRIS-KS was defined as abrupt clinical worsening of KS lesions and/or fever after ruling out another infection following cART initiation, and at least three of the following: thrombocytopenia, anemia, hyponatremia, or hypoalbuminemia.

RESULTS

40 patients were randomized and 37 completed the study. In the ITT analysis, at 48 weeks, total mortality was the same in both groups (3/20), severe-IRIS-KS attributable mortality was 0/20 in the EG, compared with 3/20 in the CG (p = 0.09), similar to the per-protocol analysis: 0/18 in the EG, and 3/19 in the control group (p = 0.09). The crude incidence rate of severe-IRIS-KS was four patients developed a total of 12 episodes of Severe-IRIS-KS in the CG and two patients developed one episode each in the EG. Mortality in patients with pulmonary KS was nil in the EG (0/5) compared with 3/4 in the CG (P = 0.048). No difference was found between groups in the number of non-S-IRIS-KS events. Among survivors at week 48, 82% achieved >80% remission.

CONCLUSIONS

Although mortality attributable to KS was lower in the EG the difference was not statistically significant.

Kaposi's Sarcoma Management from a Plastic Surgery Perspective

Kaposi's Sarcoma (KS) is a low-grade angioproliferative tumor arising from endothelial cells and associated with Human Herpes Virus 8 infection. Although KS cases are not rare and there are considerable number of patients referred for surgical excision, the plastic surgery literature on KS is exceptionally scarce. Thirty patients who were operated with the diagnosis of KS between March 2015 and January 2020 were included. Preoperative HIV tests and detailed whole-body examinations of the patients were performed. As a surgical method, for lesions with sizes ranging from 0.5 * 1 cm to 2 * 3 cm, excisions were made over the deep skin fascia by placing a margin between 0.5-1 cm, considering the anatomical location and elasticity of the skin. Primary repair was performed in 40 lesions and 12 lesions of 8 patients were repaired with a skin graft. In four patients the repair was performed with local skin flaps. Higher upper extremity involvement, less systemic involvement and less pronounced male predominance have been important results in our study that we have found different from the literature data. Compared to the therapies such as radiotherapy, laser, or chemotherapy which require several administrations; one-stage surgical excision of the lesions provides remarkable advantages.

Cellulitis in patients with chronic lower-limb lymphedema due to HIV-related Kaposi sarcoma

OBJECTIVE

Chronic Lower Limb Lymphedema (CL-LL) secondary to Kaposi sarcoma (KS) has not been recognized as a risk factor for cellulitis. The aim was to describe the clinical spectrum and use of antimicrobial prophylaxis in patients with cellulitis and CL-LL due to KS.

METHODS

HIV patients with KS, CL-LL, and at least one episode of cellulitis seen at the AIDS Cancer Clinic at INCan in Mexico from 2004 to 2019 were included. Demographic and clinical data were obtained from medical records.

RESULTS

Thirty-nine men all with CL-LL were included. Clinical factors associated with cellulitis were groin and/or lymph-node KS infiltration (69.2%), onychomycosis and/or tinea pedis (44.7%), ulcerated lesions (38.4%), and obesity (2.5%). Eighteen (46.1%) were hospitalized in the first episode and eight (20.5%) in recurrence. Six (25.3%) died, two of toxic shock syndrome (TSS), and one of septic shock. Fourteen (35.8%) had at least one recurrent episode of cellulitis. Twenty-five (64.1%) received prophylaxis. Patients without prophylaxis had significantly more unfavorable outcomes (hospitalization and recurrences) than those with prophylaxis.

CONCLUSIONS

CL-LL due to KS is a risk factor for cellulitis and severe complications in patients with a long life expectancy. Antimicrobial prophylaxis needs to be explored as it could prevent complications.

Kaposi sarcoma: What to do with a negative human herpesvirus 8 immunohistochemical stain?

Kaposi sarcoma (KS) is an intermediate vascular sarcoma that can cause significant morbidity and mortality in patients if left untreated. It is associated with human herpesvirus 8 (HHV-8) infection. Definitive diagnosis is supported by classic histopathology including slit-like vascular spaces, spindle cells, lymphocyte infiltration, and extravasated red blood cells on H&E stain and positive immunohistochemical (IHC) staining for HHV-8. We present a challenge we encountered in detecting HHV-8 by IHC in a mucosal lesion demonstrating classic histopathology for KS.

Rare Laryngeal Kaposi’s Sarcoma: Case Report and Innovative Surgical Approach

Kaposi’s sarcoma is an angioproliferative neoplasm that usually appears on the skin, but can also involve all organs and anatomic locations. The atypical manifestations of Kaposi’s sarcoma can mislead the diagnosis, which can result in a poor case management. The authors present a HIV-negative patient with Kaposi’s sarcoma with both usual and unusual locations such as the larynx, eyelids and bones. In the pre-therapeutic balance, we used NBI, which showed an intensely vascularized tumor in the larynx. The chosen method for treatment consisted in subtotal epiglotectomy performed under TransOral UltraSonic Surgery (TOUSS) approach. The use of TOUSS endoscopic surgery helped reduce the time of hospitalization, the patient did not need a nasogastric tube and was orally fed from the first postoperative day, with a better and faster functional recovery.

Corticosteroid-induced Kaposi's Sarcoma Revealed by Severe Anemia: A Case Report and Literature Review

We herein report a case of gastrointestinal (GI) Kaposi's sarcoma (KS) without cutaneous involvement in a 73-year-old man who had received immunosuppressive drugs for granulomatosis with polyangiitis. After one year of prednisolone use, he presented with tarry stool and severe anemia. Endoscopic and pathological examinations revealed bright-reddish protruding lesions with proliferating spindle cells positive for D2-40, CD34, and HHV-8, which are definitively diagnostic of GI-KS. Drug-induced KS without HIV infection or transplantation is extremely rare, and its clinical features remain unknown. Therefore, we conducted a literature review of steroid-induced KS.

Change in Pattern of Secondary Cancers After Kaposi Sarcoma in the Era of Antiretroviral Therapy

Importance

Studies performed in the 1980s and early 1990s have shown that people who develop Kaposi sarcoma (KS) are at higher risk of developing other cancers. The demographics of those affected with human immunodeficiency virus (HIV)/AIDS and KS have changed, and individuals with HIV/AIDS and KS now live longer.

Objectives

To test the hypothesis that the secondary cancers developing in patients with KS have changed in recent years and to assess the risk of secondary cancers after KS in different periods.

Design, Setting, and Participants

Longitudinal data from 9 cancer registries in the Surveillance, Epidemiology, and End Results (SEER) database were used to identify cases of KS diagnosed from January 1973 to December 2013. The dates of the analysis were November 2016 to February 2017.

Main Outcomes and Measures

The primary outcome was the development of secondary cancers in individuals with KS. Secondary cancers were considered only if diagnosed 2 months after a diagnosis of KS. Standardized incidence ratios (SIRs) were calculated for the development of new secondary cancers in the pre-AIDS era (1973-1979), pre-highly active antiretroviral therapy (HAART) era (1980-1995), and HAART era (1996-2013). Stratified analysis was then performed on a subset of the cases diagnosed from 1996 to 2013 based on age at diagnosis (<65 and ≥65 years), latency period between KS and the development of secondary cancers (1 year, 2-5 years, >5 to 10 years, and >10 years), and registries with higher vs lower reported rates of HIV/AIDS.

Results

Among 14 905 individuals with diagnosed KS, 13 721 (92.1%) were younger than 65 years at the time of diagnosis, and 14 356 (96.3%) were male. From 1980 to 1995, SIRs were 2.01 (95% CI, 1.00-3.60) for cancer of the rectum, 49.70 (95% CI, 33.53-70.94) for cancer of the anus, 4.98 (95% CI, 2.79-8.22) for cancer of the liver, 13.70 (95% CI, 2.82-40.03) for cancer of the cervix, 6.40 (95% CI, 2.76-12.60) for Hodgkin lymphoma, and 48.97 (95% CI, 44.85-53.36) for non-Hodgkin lymphoma. From 1996 to 2013, cancer of the anus, Hodgkin lymphoma, non-Hodgkin lymphoma, and cancer of the liver remained associated with KS, with the addition of the following significant SIRs: 6.99 (95% CI, 3.20-13.27) for cancer of the tongue, 10.28 (95% CI, 1.24-37.13) for cancer of the penis, and 17.62 (95% CI, 3.63-51.49) for acute lymphocytic leukemia. The SIR of developing any tumor after KS decreased significantly from 3.36 to 1.94 from the pre-HAART era to the HAART era.

Conclusions and Relevance

There has been a significant decline in the overall risk of secondary cancers after KS. Certain cancers, including acute lymphocytic leukemia, cancer of the tongue, and cancer of the penis, are increasingly becoming more common in the HAART era compared with the pre-HAART era. Close monitoring and screening for these secondary cancers is desirable in patients with KS.

Clinico-epidemiologic characteristics and patterns of care in Kaposi's sarcoma: Data from a single-institution series

In the late 20th to early 21st century, most new Kaposi's sarcoma cases were associated with HIV coinfection and low CD4 T-cell counts. After introduction of effective antiretroviral therapy, the clinical and epidemiologic characteristics of Kaposi's sarcoma may have changed. We analyzed and now report on 27 consecutive Kaposi's sarcoma patients treated at our institution from 2007 to 2017. Most patients were HIV-positive Caucasian men on antiretroviral therapy; the average CD4 T-cell count was above the AIDS-defining level of 200 cells/mm³. Seven patients had Kaposi's sarcoma with mucosal involvement, and 20 had skin-only Kaposi's sarcoma. Mucosal Kaposi's sarcoma patients had a mean CD4 T-cell count of 83 cells/mm³ as opposed to 381 cells/mm³ for patients with skin-only involvement (p = 0.005). Survival was significantly compromised in both groups but even more so in Kaposi's sarcoma patients with mucosal involvement (306 vs. 609 days). Along with other reports, our findings suggest that Kaposi's sarcoma may develop in HIV patients in the modern era despite well-controlled HIV disease. This is significant since Kaposi's sarcoma remains an important contributor to morbidity and mortality in HIV-infected patients.

Disseminated AIDS-related Kaposi's sarcoma

We present a case of disseminated Kaposi’s sarcoma with both cutaneous and extracutaneous involvement in an HIV-infected patient with a relatively high CD4 count of 369 cell/mm³. He developed chronic diarrhea, constitutional symptoms, worsening bilateral pleural effusion with respiratory distress, and progression of skin lesions distributed over his chest and extremities. The temporal relationship between rapid clinical progression and initiation of HAART suggested the possibility of Kaposi’s sarcoma-associated immune reconstitution inflammatory syndrome, which eventually resulted in the death of this patient.

Eyelid Kaposi Sarcoma in an HIV-negative Patient

Kaposi sarcoma (KS) is a low-grade, multicentric vascular neoplasm. Most commonly, it involves the skin, but it can occur at any site on the body. The cutaneous lesions are often located on the lower legs, genitalia, oral mucosa, and face. KS is categorized in four different types: classic, endemic, epidemic or AIDS associated, and transplantation associated. We report a case of HIV-negative, classic KS located on the eyelid. The eyelid lesion was completely excised, and after a 1-year follow-up, no recurrences were observed. Ocular involvement by KS in a patient who is serologically negative for HIV is extremely rare.

Chronic cough conundrum: a case report of a new diagnosis of HIV and pulmonary Kaposi's sarcoma

Background

When evaluating a common complaint such as cough, clinicians should rely on a patient’s history and physical to guide them, but also not diverge from guidelines in screening and testing lest certain diagnoses be overlooked.

Case Presentation

A 44 year old Hispanic male presented to a pulmonologist’s office after failing multiple courses of antibiotics for chronic cough, now six months in duration. He described intermittent scant hemoptysis and an evanescent migratory non-pruritic rash occasionally noted on his trunk or limbs. Due to financial concerns, the patient initially agreed only to limited testing. Eventually bronchoscopy was pursued, but results were pending when the patient presented to the emergency room with worsening dyspnea, blood-tinged sputum and weight loss. A diagnosis of Kaposi’s sarcoma (KS) of the lung was confirmed by histopathologic staining and HIV/AIDS was confirmed (HIV1 PCR 70,900 copies/mL, CD4 count 26 cells/mm³). He had repeatedly denied HIV risk factors to all providers, but once the diagnosis was established, he confirmed sexual promiscuity prior to his marriage greater than 10 years ago. He was started on HAART before initiating therapy for his KS due to concern for immune reconstitution syndrome worsening his pulmonary status.

Conclusion

Pulmonary Kaposi’s sarcoma is an infrequent diagnosis, yet risk is significantly greater for those with HIV infection. Diagnosis is difficult, with both symptoms and radiographic findings being nonspecific and not distinctly different from the appearance of pulmonary opportunistic infections. Without treatment, patients with pulmonary KS have median survival of months, but with chemotherapy and HAART they may achieve relief from symptoms and improve survival.

Following recommended screening guidelines and furthering diagnostic evaluation for persistently symptomatic patients are key to uncovering potentially fatal disease even for patients whose symptoms may seem as common and benign as an irritating cough.

Phosphoproteomic Analysis of KSHV-Infected Cells Reveals Roles of ORF45-Activated RSK during Lytic Replication

Kaposi’s Sarcoma-Associated Herpesvirus (KSHV) is an oncogenic virus which has adapted unique mechanisms to modulate the cellular microenvironment of its human host. The pathogenesis of KSHV is intimately linked to its manipulation of cellular signaling pathways, including the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway. We have previously shown that KSHV ORF45 contributes to the sustained activation of both ERK and p90 ribosomal S6 kinase (RSK, a major functional mediator of ERK/MAPK signaling) during KSHV lytic replication. ORF45-activated RSK is required for optimal KSHV lytic gene expression and progeny virion production, though the underlying mechanisms downstream of this activation are still unclear. We hypothesized that the activation of RSK by ORF45 causes differential phosphorylation of cellular and viral substrates, affecting biological processes essential for efficient KSHV lytic replication. Accordingly, we observed widespread and significant differences in protein phosphorylation upon induction of lytic replication. Mass-spectrometry-based phosphoproteomic screening identified putative substrates of ORF45-activated RSK in KSHV-infected cells. Bioinformatic analyses revealed that nuclear proteins, including several transcriptional regulators, were overrepresented among these candidates. We validated the ORF45/RSK-dependent phosphorylation of several putative substrates by employing KSHV BAC mutagenesis, kinase inhibitor treatments, and/or CRISPR-mediated knockout of RSK in KSHV-infected cells. Furthermore, we assessed the consequences of knocking out these substrates on ORF45/RSK-dependent regulation of gene expression and KSHV progeny virion production. Finally, we show data to support that ORF45 regulates the translational efficiency of a subset of viral/cellular genes with complex secondary structure in their 5’ UTR. Altogether, these data shed light on the mechanisms by which KSHV ORF45 manipulates components of the host cell machinery via modulation of RSK activity. Thus, this study has important implications for the pathobiology of KSHV and other diseases in which RSK activity is dysregulated.

Kaposi’s sarcoma-associated herpesvirus (KSHV) is a human tumor virus which hijacks the host signaling pathways in order to maintain persistent infection. We previously discovered that the KSHV protein ORF45 binds to and activates the cellular kinase RSK (p90 ribosomal S6 kinase), and that this activation is vital for optimal KSHV gene expression and virion production. Here, we performed a phosphoproteomic analysis of KSHV-infected cells to further characterize the specific substrates of ORF45-activated RSK. Bioinformatic analyses provided insights into the functional roles of these substrates. We verified the ORF45/RSK-dependent phosphorylation of a subset of these substrates by various means. Finally, we used genome editing to knock out RSK, as well as several cellular substrates identified by our screening, and characterized the consequent effect(s) on regulation of gene expression and virion production. Thus, this work further elucidates one of the key signaling nodes modulated by KSHV, and implicates ORF45-mediated activation of RSK in the regulation of viral and host gene expression during KSHV lytic replication.

Human immunodeficiency virus-1 (HIV-1)-mediated apoptosis: new therapeutic targets

HIV has posed a significant challenge due to the ability of the virus to both impair and evade the host’s immune system. One of the most important mechanisms it has employed to do so is the modulation of the host’s native apoptotic pathways and mechanisms. Viral proteins alter normal apoptotic signaling resulting in increased viral load and the formation of viral reservoirs which ultimately increase infectivity. Both the host’s pro- and anti-apoptotic responses are regulated by the interactions of viral proteins with cell surface receptors or apoptotic pathway components. This dynamic has led to the development of therapies aimed at altering the ability of the virus to modulate apoptotic pathways. These therapies are aimed at preventing or inhibiting viral infection, or treating viral associated pathologies. These drugs target both the viral proteins and the apoptotic pathways of the host. This review will examine the cell types targeted by HIV, the surface receptors exploited by the virus and the mechanisms whereby HIV encoded proteins influence the apoptotic pathways. The viral manipulation of the hosts’ cell type to evade the immune system, establish viral reservoirs and enhance viral proliferation will be reviewed. The pathologies associated with the ability of HIV to alter apoptotic signaling and the drugs and therapies currently under development that target the ability of apoptotic signaling within HIV infection will also be discussed.

Claudin-2 downregulation by KSHV infection is involved in the regulation of endothelial barrier function

BACKGROUND

Kaposi sarcoma (KS), caused by the infection of Kaposi sarcoma-associated herpesvirus (KSHV), is a disease manifested mainly by dark purple skin and mouth nodules. Cancer care studies showed that co-infection of KSHV and human immunodeficiency virus (HIV) was able to increase the patients' survival, but the underlying mechanisms are still elusive.

METHODS

To understand the mechanism underlying the prolonged survival in KSHV-HIV co-infected patients, we performed microarray analysis on RNA extracted from biopsies from KS tumors and adjacent healthy tissues in four KS patients. Subsequently, we performed hierarchical clustering, gene ontology (GO) and ingenuity pathway analysis. We then characterized the roles of tight junction protein claudin-2 in the endothelial barrier function.

RESULTS

Three hundred and forty-three differentially expressed genes were identified, of which 246 genes exhibited significantly increased expression in the tumor compared to the adjacent healthy tissue and 97 genes showed downregulated expression, including claudin-2. Knockdown of claudin-2 in cultured endothelial cells enhances barrier function by altering the charge selectivity, but not the size selectivity.

CONCLUSION

Claudin-2 expression is decreased in KS tumors from patients co-infected with KSHV and HIV. Decreased claudin-2 enhances endothelial barrier function and may play a role in the prolonged survival of patients with KSHV and HIV co-infection.

Imatinib: a breakthrough of targeted therapy in cancer

Deregulated protein tyrosine kinase activity is central to the pathogenesis of human cancers. Targeted therapy in the form of selective tyrosine kinase inhibitors (TKIs) has transformed the approach to management of various cancers and represents a therapeutic breakthrough. Imatinib was one of the first cancer therapies to show the potential for such targeted action. Imatinib, an oral targeted therapy, inhibits tyrosine kinases specifically BCR-ABL, c-KIT, and PDGFRA. Apart from its remarkable success in CML and GIST, Imatinib benefits various other tumors caused by Imatinib-specific abnormalities of PDGFR and c-KIT. Imatinib has also been proven to be effective in steroid-refractory chronic graft-versus-host disease because of its anti-PDGFR action. This paper is a comprehensive review of the role of Imatinib in oncology.

An interesting case of 'diabetic foot ulcer' in an HIV-positive patient

Kaposi sarcoma is a highly vascularised tumour affecting the skin, lymph nodes and viscera. Kaposi sarcoma is most common in HIV-infected homosexual or bisexual men. We present here a 70-year-old white British male patient, who was under the care of the podiatric team for longstanding 'diabetic foot ulcers'. He was later referred to the Dermatology team who took a biopsy; this revealed features of Kaposi sarcoma which prompted an HIV test which was positive. This patient had previously presented to several healthcare professionals with symptoms suggestive of HIV infection. He was started on antiretroviral therapy and the HIV and human herpesvirus-8 viral loads became undetectable in the blood within weeks and he showed significant clinical improvement. This case report is a reminder to clinicians to have a high index of suspicion in patients presenting with symptoms and signs suggestive of HIV infection.

Site-specific association with host and viral chromatin by Kaposi's sarcoma-associated herpesvirus LANA and its reversal during lytic reactivation

Latency-associated nuclear antigen (LANA), a multifunctional protein expressed by the Kaposi sarcoma-associated herpesvirus (KSHV) in latently infected cells, is required for stable maintenance of the viral episome. This is mediated by two interactions: LANA binds to specific sequences (LBS1 and LBS2) on viral DNA and also engages host histones, tethering the viral genome to host chromosomes in mitosis. LANA has also been suggested to affect host gene expression, but both the mechanism(s) and role of this dysregulation in KSHV biology remain unclear. Here, we have examined LANA interactions with host chromatin on a genome-wide scale using chromatin immunoprecipitation with high-throughput sequencing (ChIP-seq) and show that LANA predominantly targets human genes near their transcriptional start sites (TSSs). These host LANA-binding sites are generally found within transcriptionally active promoters and display striking overrepresentation of a consensus DNA sequence virtually identical to the LANA-binding site 1 (LBS1) motif in KSHV DNA. Comparison of the ChIP-seq profile with whole-transcriptome (high-throughput sequencing of RNA transcripts [RNA-seq]) data reveals that few of the genes that are differentially regulated in latent infection are occupied by LANA at their promoters. This suggests that direct LANA binding to promoters is not the prime determinant of altered host transcription in KSHV-infected cells. Most surprisingly, the association of LANA to both host and viral DNA is strongly disrupted during the lytic cycle of KSHV. This disruption can be prevented by the inhibition of viral DNA synthesis, suggesting the existence of novel and potent regulatory mechanisms linked to either viral DNA replication or late gene expression.

IMPORTANCE

Here, we employ complementary genome-wide analyses to evaluate the distribution of the highly abundant latency-associated nuclear antigen, LANA, on the host genome and its impact on host gene expression during KSHV latent infection. Combined, ChIP-seq and RNA-seq reveal that LANA accumulates at active gene promoters that harbor specific short DNA sequences that are highly reminiscent of its cognate binding sites in the virus genome. Unexpectedly, we found that such association does not lead to remodeling of global host transcription during latency. We also report for the first time that LANA's ability to bind host and viral chromatin is highly dynamic and is disrupted in cells undergoing an extensive lytic reactivation. This therefore suggests that the association of LANA to chromatin during a productive infection cycle is controlled by a new regulatory mechanism.

A unique herpesviral transcriptional program in KSHV-infected lymphatic endothelial cells leads to mTORC1 activation and rapamycin sensitivity

Immunosuppression therapy following organ transplantation is a significant factor in the development and progression of Kaposi's sarcoma-associated herpesvirus (KSHV)-induced posttransplant Kaposi's sarcoma (KS). Switching from cyclosporine to the mTOR inhibitor rapamycin is reported to promote KS regression without allograft rejection. Examining the underlying molecular basis for this clinical observation, we find that KSHV infection selectively upregulates mTOR signaling in primary human lymphatic endothelial cells (LECs), but not blood endothelial cells (BECs), and sensitizes LECs to rapamycin-induced apoptosis. Viral transcriptome analysis revealed that while infected BECs display conventional latency, KSHV-infected LECs support a radically different program involving widespread deregulation of both latent and lytic genes. ORF45, a lytic gene selectively expressed in infected LECs, is required for mTOR activation and critical for rapamycin sensitivity. These studies reveal the existence of a unique herpesviral gene expression program corresponding to neither canonical latency nor lytic replication, with important pathogenetic and therapeutic consequences.

Consensus of the Brazilian Society of Infectious Diseases and Brazilian Society of Clinical Oncology on the management and treatment of Kaposi's sarcoma

Kaposi's sarcoma is a multifocal vascular lesion of low-grade potential that is most often present in mucocutaneous sites and usually also affects lymph nodes and visceral organs. The condition may manifest through purplish lesions, flat or raised with an irregular shape, gastrointestinal bleeding due to lesions located in the digestive system, and dyspnea and hemoptysis associated with pulmonary lesions. In the early 1980s, the appearance of several cases of Kaposi's sarcoma in homosexual men was the first alarm about a newly identified epidemic, acquired immunodeficiency syndrome. In 1994, it was finally demonstrated that the presence of a herpes virus associated with Kaposi's sarcoma called HHV-8 or Kaposi's sarcoma herpes virus and its genetic sequence was rapidly deciphered. The prevalence of this virus is very high (about 50%) in some African populations, but stands between 2% and 8% for the entire world population. Kaposi's sarcoma only develops when the immune system is depressed, as in acquired immunodeficiency syndrome, which appears to be associated with a specific variant of the Kaposi's sarcoma herpes virus.

There are no treatment guidelines for Kaposi's sarcoma established in Brazil, and thus the Brazilian Society of Clinical Oncology and the Brazilian Society of Infectious Diseases developed the treatment consensus presented here.

Kaposi's sarcoma in patients with and without human immunodeficiency virus infection, in a tertiary referral centre in Kenya

The clinical features of Kaposi's sarcoma (KS), in patients with and without HIV infection, were investigated in a tertiary referral centre in Kenya between 1997 and 1999. Although 186 cases were identified prospectively, the data analysis was restricted to the 91 (49%) cases who had pathological confirmation of Kaposi's sarcoma and documented HIV serostatus. Among these 91 subjects (58% of whom were male), the age-group holding the largest number of KS cases was that of individuals aged 31-40 years; most of the paediatric cases were aged 6-10 years. The ratio of HIV-seropositives to HIV-seronegatives was 8.5:1 for the adult cases and 0.9:1 for the paediatric. Of the signs and symptoms of Kaposi's sarcoma seen at presentation, only peripheral lympadenopathy was found to be significantly associated with underlying HIV infection (P = 0.05). The median survival was 104 days. It is apparent that, as the HIV epidemic advances in regions of the world with endemic KS, the clinical presentation and natural history of the endemic KS are blending with those of the epidemic or AIDS-associated disease, leading to a reduction in the mean age of the cases and a nearly identical incidence in men and women. In regions of the world where patients have ready access to such chemotherapy, the impact of treatment with highly active antiretroviral drugs on the incidence and natural history of KS has been dramatic. It will be important to monitor the clinico-pathological features of KS in the developing world, as more active antiretroviral regimens become available in clinical practice there.

Predictive clinical factors in the diagnosis of gastrointestinal Kaposi's sarcoma and its endoscopic severity

BACKGROUND

The diagnosis of gastrointestinal (GI) involvement in Kaposi's sarcoma (KS) is important to make because the need for treatment depends on the extent of the disease. Moreover, severe GI lesions can cause serious complications. Endoscopy with biopsy is an extremely useful method to diagnose GI-KS. However, determining the indications for endoscopy is difficult because KS can occur without GI symptoms or cutaneous KS. This study sought to clarify predictive clinical factors for GI-KS and its severity on endoscopy.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 1,027 HIV-infected patients who underwent endoscopy were analyzed. Sexual behavior, CD4 count, HIV RNA, history of highly active antiretroviral therapy (HAART), GI symptoms, and cutaneous KS were assessed. Endoscopic severity including bulky tumor, ulceration, and number of lesions were evaluated. Thirty-three patients had GI-KS and 46 patients cutaneous KS. Among the GI-KS patients, 78.8% (26/33) had no GI symptoms and 24.2% (8/33) had no cutaneous KS. Univariate analysis identified men who have sex with men (MSM), CD4 <100 cells/µL, HIV RNA ≥10,000 copies/mL, no history of HAART, and cutaneous KS were significantly associated with GI-KS. Among these factors, cutaneous KS was closely related to GI-KS on multivariable analysis. Among patients without cutaneous KS, MSM and CD4 count <100 cells/µL were the only independent clinical factors related to GI-KS. Bulky tumor was significantly associated with CD4 <100 cells/µL and large number of lesions was significantly associated with HIV-RNA ≥10,000 copies/mL.

CONCLUSIONS

To diagnose GI-KS, clinical factors need to be considered before endoscopy. The presence of GI symptoms is not useful in predicting GI-KS. MSM and CD4 count <100 cells/µL are predictive factors among patients without cutaneous KS. Caution should be exercised especially in patients with low CD4 counts or high HIV viral loads as they are more likely to develop severe GI-KS lesions.

False-Negative Results of Endoscopic Biopsy in the Diagnosis of Gastrointestinal Kaposi's Sarcoma in HIV-Infected Patients

Kaposi's sarcoma (KS) is a rare endothelial neoplasm mainly involving the skin, but it is often associated with AIDS. Diagnosis of gastrointestinal (GI) tract KS, a common site of visceral involvement in AIDS, is important, but endoscopic biopsy carries a risk of false-negative results (FNRs) due to its submucosal appearance. This study sought to determine the rate and causes of FNR for endoscopic biopsy of GI-KS lesions. Endoscopic biopsy samples of 116 GI-KS lesions were reviewed retrospectively. All GI-KS lesions were confirmed to be resolved following KS therapy. FNRs were yielded for 41 of the lesions (35.3%). Among upper and lower GI sites, the esophagus was the only site significantly associated with FNRs (P < 0.01). Small size (<10 mm) and patches found on endoscopy were significantly associated with FNRs (P < 0.05). Findings of submucosal tumor (SMT) with ulceration were significantly associated with true-positive results (P < 0.05). In conclusion, FNRs were found in 35.3% of GI-KS lesions and were especially related to the site of the esophagus and endoscopic early stage (small size or patch appearance). An SMT with ulceration may be relatively easy to diagnose on endoscopic biopsy. Caution should be exercised when performing endoscopic biopsy of these lesions in AIDS patients and evaluating the histological features.

Tegument Proteins of Kaposi's Sarcoma-Associated Herpesvirus and Related Gamma-Herpesviruses

A herpesvirus virion is composed of a viral genomic DNA-containing capsid surrounded by a viral envelope with glycoprotein spikes on its surface. Located between the capsid and the outer viral envelope is the virion tegument layer. Though the majority of the virion proteins are located in the tegument, this layer is less studied and was thought to be an amorphous structure. Over the last decade, a number of studies have indicated the presence of organized tegument structures across the spectrum of herpesviruses, implicating tegument components in critical steps governing the viral life cycle. In the case of Kaposi’s sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi’s sarcoma, several functions exerted by tegument proteins at different stages of the viral life cycle, inclusive of primary de novo infection and virion assembly, have been identified over the last several years. In this review, KSHV tegument components are cataloged and the occurrence of organized tegument structures in KSHV, built through interactions amongst the different virion proteins, is discussed in depth. The significant functional roles of the KSHV tegument proteins at different stages of the viral life cycle are elaborated under separate headings. Definitive functional roles exerted by tegument proteins of related gamma-herpesviruses are also discussed. Since tegument proteins play key roles during viral assembly, viral entry, and represent an important interface for virus–host interactions, further research in this area should provide detailed insights into the functional capacity of the KSHV tegument, resulting in a better understanding of the viral life cycle.

Kaposi sarcoma in the setting of cushing disease

OBJECTIVE

To report a case of a human immunodeficiency virus (HIV)-negative Kaposi sarcoma (KS) associated with Cushing disease (CD).

METHODS

The details of case presentation, evaluation, diagnosis, and treatment are presented and cases of KS and CD published before November 1, 2010 on PubMed and Scopus are reviewed.

RESULTS

A 54-year-old Hispanic HIV-negative man presented with typical signs and symptoms of CD (easy bruisability, proximal muscle wasting, and abdominal fat pads). Numerous raised, purplish, nonblanching plaques 0.5 to 2 cm in diameter extended throughout his lower extremities. Biochemical tests and pituitary magnetic resonance imaging confirmed CD. A lesion biopsy showed atypical vascular proliferation positive by immunohistochemistry for human herpesvirus 8 (HHV-8), consistent with KS. He underwent 2 transsphenoidal surgeries followed by a bilateral adrenalectomy. After recovery, his KS was treated with a systemic combination of liposomal doxorubicin and paclitaxel.

CONCLUSION

The occurrence of CD and KS is rare. Specific therapy for CD and chemotherapy for KS are effective in the treatment of KS associated with CD.

Etoposide, vincristine, doxorubicin and dexamethasone (EVAD) combination chemotherapy as second-line treatment for advanced AIDS-related Kaposi's sarcoma

OBJECTIVE

To evaluate through retrospective analysis the efficacy and toxicity of combination chemotherapy with etoposide, vincristine, doxorubin and dexamethasone (EVAD) as second-line therapy in patients with advanced AIDS-related Kaposi's sarcoma (AIDS-KS) after failure of first-line chemotherapy.

METHODS

Eighty-eight patients with poor-risk AIDS-KS were treated intravenously with combination chemotherapy with EVAD; etoposide at a dose of 100 mg/m(2) on three consecutive days, vincristine 1.4 mg/m(2) with a maximum single dosage of 2.0 mg on day one, doxorubicin 30 mg/m(2) on day one and dexamethasone 40 mg on three consecutive days, with a three week cycle. All eligible patients had relapsed or progressed after prior two to six cycles of combination chemotherapy with doxorubicin, bleomycin and vincristine (ABV) or bleomycin and vincristine (BV).

RESULTS

Assessment of the response of all the patients was made. The overall objective response rate was 59.1% (95% CI 48.83-69.37%), with five complete responses and 47 partial responses. Twenty-six cases of stable disease and 10 of progressive disease were observed in the remaining patients. The median follow-up period was 27 months (range 8-52 months). The median time to progression was 6.80 months (95% CI 2.04-11.56 months), and the median overall survival was 14.24 months (95% CI 10.26-18.22 months). Leucopenia was seen in 92.0% of patients, of which 20 patients had grade 3 and 12 had grade 4. Conclusions Combination chemotherapy with EVAD offers a new, active and safe therapeutic approach for the treatment of advanced AIDS-related KS.

Evasion and subversion of interferon-mediated antiviral immunity by Kaposi's sarcoma-associated herpesvirus: an overview

Viral invasion of a host cell triggers immune responses with both innate and adaptive components. The innate immune response involving the induction of type I interferons (alpha and beta interferons [IFN-α and -β]) constitutes the first line of antiviral defenses. The type I IFNs signal the transcription of a group of antiviral effector proteins, the IFN-stimulated genes (ISGs), which target distinct viral components and distinct stages of the viral life cycle, aiming to eliminate invading viruses. In the case of Kaposi's sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi's sarcoma (KS), a sudden upsurge of type I IFN-mediated innate antiviral signals is seen immediately following both primary de novo infection and viral lytic reactivation from latency. Potent subversion of these responses thus becomes mandatory for the successful establishment of a primary infection following viral entry as well as for efficient viral assembly and egress. This review gives a concise overview of the induction of the type I IFN signaling pathways in response to viral infection and provides a comprehensive understanding of the antagonizing effects exerted by KSHV on type I IFN pathways wielded at various stages of the viral life cycle. Information garnered from this review should result in a better understanding of KSHV biology essential for the development of immunotherapeutic strategies targeted toward KSHV-associated malignancies.

Metastatic Kaposi's Sarcoma with Perirectal Involvement Diagnosed with Endoscopic Ultrasound-Guided EchoBrush Cytology Sampling

AIDS-related Kaposi's sarcoma (KS) is a low-grade vascular tumor that occurs in association with human herpesvirus 8 infection. Here we report the case of a 21-year-old male with recently diagnosed cutaneous KS who presented with rectal bleeding and anal pruritus. Initial endoscopic evaluation was nondiagnostic. CT imaging showed diffuse lymphadenopathy including perirectal involvement which was suspicious for metastatic KS. Echoendoscopy with needle biopsies and EchoBrush sampling of the lymph nodes revealed spindle cells confirming metastatic KS. Treatment was initiated with liposomal doxorubicin resulting in rapid improvement of the skin lesions. After treatment completion, repeat CT imaging showed improved lymphadenopathy. No further rectal bleeding or perianal pruritus was reported. Although the EchoBrush has previously been used to aid in the diagnosis of pancreatic lesions, this report describes a novel use of EchoBrush to diagnose KS from perirectal lymph nodes.

Morgellons disease: Analysis of a population with clinically confirmed microscopic subcutaneous fibers of unknown etiology

BACKGROUND

Morgellons disease is a controversial illness in which patients complain of stinging, burning, and biting sensations under the skin. Unusual subcutaneous fibers are the unique objective finding. The etiology of Morgellons disease is unknown, and diagnostic criteria have yet to be established. Our goal was to identify prevalent symptoms in patients with clinically confirmed subcutaneous fibers in order to develop a case definition for Morgellons disease.

METHODS

Patients with subcutaneous fibers observed on physical examination (designated as the fiber group) were evaluated using a data extraction tool that measured clinical and demographic characteristics. The prevalence of symptoms common to the fiber group was then compared with the prevalence of these symptoms in patients with Lyme disease and no complaints of skin fibers.

RESULTS

The fiber group consisted of 122 patients. Significant findings in this group were an association with tick-borne diseases and hypothyroidism, high numbers from two states (Texas and California), high prevalence in middle-aged Caucasian women, and an increased prevalence of smoking and substance abuse. Although depression was noted in 29% of the fiber patients, pre-existing delusional disease was not reported. After adjusting for nonspecific symptoms, the most common symptoms reported in the fiber group were: crawling sensations under the skin; spontaneously appearing, slow-healing lesions; hyperpigmented scars when lesions heal; intense pruritus; seed-like objects, black specks, or "fuzz balls" in lesions or on intact skin; fine, thread-like fibers of varying colors in lesions and intact skin; lesions containing thick, tough, translucent fibers that are highly resistant to extraction; and a sensation of something trying to penetrate the skin from the inside out.

CONCLUSIONS

This study of the largest clinical cohort reported to date provides the basis for an accurate and clinically useful case definition for Morgellons disease.

KSHV and the pathogenesis of Kaposi sarcoma: listening to human biology and medicine

The linkage of Kaposi sarcoma (KS) to infection by a novel human herpesvirus (Kaposi sarcoma-associated herpesvirus [KSHV]) is one of the great successes of contemporary biomedical research and was achieved by using advanced genomic technologies in a manner informed by a nuanced understanding of epidemiology and clinical investigation. Ongoing efforts to understand the molecular mechanisms by which KSHV infection predisposes to KS continue to be powerfully influenced by insights emanating from the clinic. Here, recent developments in KS pathogenesis are reviewed, with particular emphasis on clinical, pathologic, and molecular observations that highlight the many differences between this process and tumorigenesis by other oncogenic viruses.

Anterior Segment and External Ocular Disorders Associated with Human Immunodeficiency Virus Disease

The eye is a common site for complications of human immunodeficiency virus (HIV) infection. Although cytomegalovirus retinitis remains the most prevalent of the blinding ocular disorders that can occur in individuals with the acquired immunodeficiency syndrome (AIDS), several important HIV-associated disorders may involve the anterior segment, ocular surface, and adnexae. Some of these entities, such as Kaposi sarcoma, were well described, but uncommon, before the HIV epidemic. Others, like microsporidial keratoconjunctivitis, have presentations that differ between affected individuals with HIV disease and those from the general population who are immunocompetent. The treatment of many of these diseases is challenging because of host immunodeficiency. Survival after the diagnosis of AIDS has increased among individuals with HIV disease because of more effective antiretroviral therapies and improved prophylaxis against, and treatment of, opportunistic infections. This longer survival may lead to an increased prevalence of anterior segment and external ocular disorders. In addition, the evaluation and management of disorders such as blepharitis and dry eye, which were previously overshadowed by more severe, blinding disorders, may demand increased attention, as the general health of this population improves. Not all individuals infected with HIV receive potent antiretroviral therapy, however, because of socioeconomic or other factors, and others will be intolerant of these drugs or experience drug failure. Ophthalmologists must, therefore, still be aware of the ocular findings that develop in the setting of severe immunosuppression. This article reviews the spectrum of HIV-associated anterior segment and external ocular disorders, with recommendations for their evaluation and management.

Selective expression of stromal-derived factor-1 in the capillary vascular endothelium plays a role in Kaposi sarcoma pathogenesis

Kaposi sarcoma (KS), the most common neoplasm in patients with AIDS, typically presents with multiple skin lesions characterized by "spindle cells," the vast majority of which are infected with KSHV (Kaposi sarcoma herpes virus, also named HHV-8). In patients with AIDS, the presence of cell-associated KSHV DNA in blood is predictive of subsequent KS development, but the mechanisms by which circulating KSHV-infected cells contribute to AIDS-KS pathogenesis are unclear. Here, we show that the chemokine stromal-derived factor-1 (SDF-1), which is constitutively expressed by skin capillary endothelium and displayed on the endothelial cell surface in association with heparan sulfate, can trigger specific arrest of KSHV-infected cells under physiologic shear flow conditions. Moreover, in the presence of soluble SDF-1 gradients, SDF-1 expressed on the endothelial barrier can promote transendothelial migration of KSHV-infected cells. By triggering specific adhesion of circulating KSHV-infected cells and favoring their entry into the extravascular cutaneous space, endothelial cell-associated SDF-1 in cutaneous capillaries may dictate the preferential occurrence of KS in the skin.

Human herpesvirus 8, Kaposi's sarcoma, and associated conditions

HHV-8 is a recently identified human herpes virus that can produce tumors, most often in immune compromised hosts. The virus is most closely associated with Kaposi's sarcoma, but is also clearly associated with primary effusion lymphomas and multicentric Castleman's disease. The prevalence of HHV-8 infection varies considerably, but is highest among men who have sex with men and others with histories of sexually transmitted diseases and high numbers of lifetime sexual partners. HHV-8 is shed in saliva, and less commonly in genital secretions. Treatment of HHV-8 associated diseases includes reversal of immune compromise either via discontinuation of immunosuppressives or immune reconstitution via antiretroviral regimens. Specific antiviral drug inhibit HHV-8 replication, and can result in responses in certain HHV-8-associated conditions.

A case series of acquired immunodeficiency syndrome patients with initial neoplastic diagnoses of intraoral Kaposi's sarcoma

BACKGROUND

Oral Kaposi's sarcoma (KS) may represent the initial clinical manifestation of immunosuppression in human immunodeficiency virus disease. This article reviews the treatment provided to these patients and the outcome of the disease and provides the opportunity to assess the impact of improvements in the medical therapy of acquired immunodeficiency syndrome on disease outcome.

METHODS

A tumor registry was examined to identify patients in whom oral KS was the first neoplastic diagnosis.

RESULTS AND CONCLUSIONS

Thirty-seven cases of oral KS representing 1.9% of all cases of KS were identified as the first malignant diagnosis in patients with acquired immunodeficiency syndrome. Patients with oral KS have limited survival; the cause of death is either infection or malignancy. In our study, the palate was the most common site of primary involvement in the oral cavity. Recently diagnosed patients remained alive longer than those diagnosed earlier, and the patients with the most recently diagnosed cases were alive at the completion of the study, suggesting that medical management of human immunodeficiency virus has improved with new therapies.

Activity of thalidomide in AIDS-related Kaposi's sarcoma

PURPOSE

To assess the toxicity and activity of oral thalidomide in Kaposi's sarcoma (KS) in a phase II dose-escalation study.

PATIENTS AND METHODS

Human immunodeficiency virus (HIV)-seropositive patients with biopsy-confirmed KS that progressed over the 2 months before enrollment received an initial dose of 200 mg/d of oral thalidomide in a phase II study. The dose was increased to a maximum of 1,000 mg/d for up to 1 year. Anti-HIV therapy was maintained during the study period. Toxicity, tumor response, immunologic and angiogenic factors, and virologic parameters were assessed.

RESULTS

Twenty patients aged 29 to 49 years with a median CD4 count of 246 cells/mm(3) (range, 14 to 646 cells/mm(3)) were enrolled. All patients were assessable for toxicity, and 17 for response. Drowsiness in nine and depression in seven patients were the most frequent toxicities observed. Eight (47%; 95% confidence interval [CI], 23% to 72%) of the 17 assessable patients achieved a partial response, and an additional two patients had stable disease. Based on all 20 patients treated, the response rate was 40% (95% CI, 19% to 64%). The median thalidomide dose at the time of response was 500 mg/d (range, 400 to 1,000 mg/d). The median duration of drug treatment was 6.3 months, and the median time to progression was 7.3 months.

CONCLUSION

Oral thalidomide was tolerated in this population at doses up to 1,000 mg/d for as long as 12 months and was found to induce clinically meaningful anti-KS responses in a sizable subset of the patients. Additional studies of this agent in KS are warranted.

Human Herpesvirus 8 Infections

Human herpesvirus 8 (HHV-8) or Kaposi's sarcoma (KS)-associated herpesvirus is a recently identified virus that is associated with KS, multicentric Castleman's disease, and body cavity-based lymphomas. KS is the most common kind of cancer in AIDS patients and the initial AIDS-defining condition in over 20% of patients. HHV-8 DNA has now been detected in over 95% of KS tissue samples supporting the concept that HHV-8 has a causal role in KS. The discovery has opened new avenues for understanding the epidemiology, pathogenesis, and treatment of KS and related conditions.

Palliative treatment of epidemic Kaposi sarcoma of the feet

Limited information is available in the medical literature on epidemic Kaposi sarcoma (EKS) of the foot. Patients with EKS of the foot can experience severe discomfort that makes it difficult to ambulate and even wear shoes. Between 1985 and 1996, 36 patients with EKS of the foot were treated with palliative intent. Most patients were referred for radiation therapy because of foot discomfort or marked difficulty with ambulation. From the pool of 36 patients, data were available at completion of treatment for 46 sites, and at 1 month for 44 sites. Morbidity was assessed for 35 sites. The median follow-up time for the 44 sites with at least 1 month follow-up was 8 months. The most frequently used regimen was a novel fractionation schedule of three fractions a week at 3.5 Gy/fx to a total dose of 21.0 Gy. The overall response rate and complete response rate for the 44 sites with at least 1 month follow-up were 91% and 80%, respectively. The 46 treated sites evaluated at the completion of treatment had a complete response rate of only 13% and an overall response rate of 63%. Of the 35 sites assessed for acute toxicity, 63% experienced discomfort related to the radiation therapy. This discomfort usually resolved without intervention within 2 weeks of completion of radiation therapy. For patients with and without a history of opportunistic infections, complete responses were observed in 8 of 12 sites (67%) and 25 of 27 sites (93%), respectively (p = 0.06). Radiation therapy for EKS of the foot yields excellent response rates, comparable with responses seen in other cutaneous sites with EKS. Appropriate patient education and support are needed because initial responses to radiation therapy are often disappointing and pedal discomfort can be exacerbated transiently. However, the discomfort resolves and complete response occurs in most patients. The 3.5-Gy triweekly fractionation schedule is a convenient and effective regimen and minimizes treatment visits for patients with ambulatory discomfort. A history of opportunistic infections appears to be a poor prognosticator of response to radiation treatments.

Sensitization of AIDS-Kaposi’s Sarcoma Cells to Apo-2 Ligand-Induced Apoptosis by Actinomycin D

Kaposi’s sarcoma (KS) is the most frequent malignancy associated with HIV infection (AIDS-KS), a complication that leads to high mortality and morbidity. AIDS-KS cells are resistant to killing by chemotherapeutic drugs/NK cells and Fas-induced apoptosis, suggesting that the acquisition of antiapoptotic characteristics by AIDS-KS cells may contribute to their prolonged survival. Apo-2 ligand (Apo-2L)/TNF-related apoptosis-inducing ligand, a new member of the TNF family, has been identified as an apoptosis-inducing molecule. In this study we examined the sensitivity of 10 different AIDS-KS isolates to Apo-2L-mediated cytotoxicity. AIDS-KS cells were relatively resistant to Apo-2L; however, Apo-2L and actinomycin D (Act D) used in combination synergistically potentiated the induction of cell death in nine of the 10 isolates. Apo-2L induced apoptosis in &gt;80% of AIDS-KS cells pretreated with Act D. The caspase inhibitors, zIETD-fmk and zDEVD-fmk, inhibited apoptosis in AIDS-KS by sApo-2L, suggesting that caspase 3-like and caspase 8 or 10 activities are essential for Apo-2L-mediated apoptosis. Act D treatment of AIDS-KS cells markedly and selectively down-regulated Bcl-xL expression, while the expressions of decoy receptors 1 and 2, Bax, cellular FLICE (Fas-associated death domain protein-like IL-1-converting enzyme) inhibitory protein, FADD (Fas-associated death domain protein), procaspase 8, and p53 were not affected. These findings suggest the possible involvement of Bcl-xL in Act D-induced sensitization of AIDS-KS cells to Apo-2L-mediated apoptosis. Furthermore, Act D did not sensitize PBMC or fibroblast cells to Apo-2L. Thus, Apo-2L and Act D used in combination may be of therapeutic value in the treatment of AIDS-KS.

Kaposi's sarcoma and human herpesvirus-8

KS is a major cause of morbidity and mortality among AIDS patients and a treatment problem in the sporadic cases that are not associated with HIV. All four forms of the disease are linked to a newly described herpesvirus, HHV-8 or KSHV, via strong epidemiologic associations and biologic plausibility as a causal agent. HHV-8 is also epidemiologically associated with body cavity-based lymphomas, which are almost unique to AIDS, and Castleman's disease. Existing radiation and chemotherapeutic treatments of KS are only partially effective and cause significant adverse effects. New preventive approaches and therapies aimed at inhibiting HHV-8 may be effective. New treatments that interfere with the molecular mechanisms that drive KS may, in the future, provide the best opportunities to control the disease.