Search

Purpose:Kaposi sarcoma (KS) is caused by Kaposi sarcoma herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8). KS, which develops most frequently among people with HIV, is generally treated with chemotherapy, but these drugs have acute and cumulative toxicities. We previously described initial results of a trial of pomalidomide, an oral immunomodulatory derivative of thalidomide, in patients with KS. Here, we present results on the full cohort and survival outcomes.Patients and Methods:Participants with KS with or without HIV were treated with pomalidomide 5 mg once daily for 21 days per 28-day cycle with aspirin 81 mg daily for thromboprophylaxis. Participants with HIV received antiretroviral therapy. Response was defined by modified version of the AIDS Clinical Trial Group KS criteria. We evaluated tumor responses (including participants who had a second course), adverse events, progression-free survival (PFS), and long-term outcomes.Results:Twenty-eight participants were enrolled. Eighteen (64%) were HIV positive and 21 (75%) had advanced (T1) disease. The overall response rate was 71%: 95% confidence interval (CI) 51%–87%. Twelve of 18 HIV-positive (67%; 95% CI, 41–87%) and 8 of 10 HIV-negative participants (80%; 95% CI, 44%–97%) had a response. Two of 4 participants who received a second course of pomalidomide had a partial response. The median PFS was 10.2 months (95% CI: 7.6–15.7 months). Grade 3 neutropenia was noted among 50% of participants. In the follow-up period, 3 participants with HIV had other KSHV-associated diseases.Conclusions:Pomalidomide is a safe and active chemotherapy-sparing agent for the treatment of KS among individuals with or without HIV.

Immunodeficiency, whether acquired in the case of human immunodeficiency virus (HIV) infection or congenital due to inborn errors of immunity (IEIs), presents clinically with not only infection and immune dysregulation but also increased risk of malignancy. The range of malignancies seen is relatively limited and attributable to the particular cellular and molecular defects in each disease. CD4+ T-cell lymphopenia in people living with HIV infection (PLWH) and certain IEIs drive the predisposition to aggressive B-cell non-Hodgkin lymphomas, including certain rare subtypes rarely seen in immunocompetent individuals. PLWH and IEI that lead to profound T-cell lymphopenia or dysfunction also are at risk of cancers related to oncogenic viruses such as Kaposi sarcoma herpesvirus, Epstein-Barr virus, human papillomavirus (HPV), and Merkel cell polyomavirus. IEIs that affect natural killer cell development and/or function heavily predispose to HPV-associated epithelial cancers. Defects in DNA repair pathways compromise T- and B-lymphocyte development during immune receptor rearrangement in addition to affecting hematopoietic and epithelial DNA damage responses, resulting in both hematologic and nonhematologic cancers. Treatment of cancers in immunodeficient individuals should be curative in intent and pursued in close consultation with disease experts in immunology and infectious disease.

BackgroundThe two oncogenic human gammaherpesviruses, Kaposi sarcoma-associated herpesvirus (KSHV) and Epstein–Barr virus (EBV), both downregulate immune surface molecules, such as MHC-I, ICAM-1, and B7-2, enabling them to evade T-cell and natural killer cell immunity. Both also either encode for human cyclin homologues or promote cellular cyclin activity, and this has been shown to be important for proliferation and survival of gammaherpesvirus-induced tumors. CDK4/6 inhibitors, which are approved for certain breast cancers, have been shown to enhance expression of MHC-I in cell lines and murine models of breast cancer, and this was attributed to activation of interferons by endogenous retrovirus elements. However, it was not known if this would occur in gammaherpesvirus-induced tumors in which interferons are already activated.MethodsMultiple KSHV/EBV-infected cell lines were treated with CDK4/6 inhibitors. The growth of viable cells and expression of surface markers was assessed. T cell activation stimulated by the treated cells was assayed by a T-cell activation bioassay. Both viral and host gene expression was surveyed using RT-qPCR.ResultsThree CDK4/6 inhibitors, abemaciclib, palbociclib, and ribociclib, inhibited cell growth in KSHV-induced primary effusion lymphoma (PEL) and EBV positive Burkitt’s lymphoma (BL) cell lines, and KSHV-infected human umbilical vein endothelial cells (HUVECs). Moreover, CDK4/6 inhibitors increased mRNA and surface expression of MHC-I in all three and prevented downregulation of MHC-I surface expression during lytic replication in KSHV-infected cells. CDK4/6 inhibitors also variably increased mRNA and surface expression of ICAM-1 and B7-2 in the tested lines. Abemaciclib also significantly enhanced T-cell activation induced by treated PEL and BL cells. Certain gammaherpesvirus genes as well as endogenous retrovirus (ERV) 3–1 genes were enhanced by CDK4/6 inhibitors in most PEL and BL lines and this enhancement was associated with expression of gamma interferon-induced genes including MHC-I.ConclusionsThese observations provide evidence that CDK4/6 inhibitors can induce expression of surface immune markers MHC-I, B7-2, and ICAM-1 in gammaherpesvirus-infected cell lines and induce virus-specific immunity. They can thus thwart virus-induced immune evasion. These effects, along with their direct effects on KSHV- or EBV-induced tumors, provide a rational for the clinical testing of these drugs in these tumors.

OBJECTIVE To assess the cytokine and viral profiles of effusions and peripheral blood among patients diagnosed with HIV and Kaposi sarcoma herpesvirus [KSHV, also known as human herpesvirus 8 (HHV-8)]-associated conditions. DESIGN Retrospective comparative study evaluating clinicopathologic findings in patients with HIV and KSHV-associated conditions presenting with an effusion between 2010 and 2018. METHODS Paired peripheral blood and effusion samples collected at the time of pathological diagnosis of KSHV-associated conditions [Kaposi sarcoma, KSHV-associated multicentric Castleman disease (KSHV-MCD), primary effusion lymphoma (PEL), or KSHV-associated inflammatory cytokine syndrome (KICS)] were evaluated for disease-specific and compartment-specific (effusion vs. blood) characteristics. We assessed 12 cytokines, KSHV viral DNA (KSHV-VL), and Epstein--Barr virus (EBV) viral DNA (EBV-VL). RESULTS Nine patients had PEL, five patients had KSHV-MCD, and eight patients met criteria for KICS; all but one patient had concurrent Kaposi sarcoma in addition to these conditions. PEL effusions had substantially higher levels of IL-13 (median 16.9 pg/ml; interquartile range 9.7--26.9 pg/ml) compared with KSHV-MCD (median

In people living with HIV (PLWH) on antiretroviral therapy (ART), virus persists in a latent form where there is minimal transcription or protein expression. Latently infected cells are a major barrier to curing HIV. Increasing HIV transcription and viral production in latently infected cells could facilitate immune recognition and reduce the pool of infected cells that persist on ART. Given that programmed cell death protein 1 (PD-1) expressing CD4 + T cells are preferentially infected with HIV in PLWH on ART, we aimed to determine whether administration of antibodies targeting PD-1 would reverse HIV latency in vivo. We therefore evaluated the impact of intravenous administration of pembrolizumab every 3 weeks on HIV latency in 32 PLWH and cancer on ART. After the first infusion of anti–PD-1, we observed a median 1.32-fold increase in unspliced HIV RNA and 1.61-fold increase in unspliced RNA:DNA ratio in sorted blood CD4 + T cells compared to baseline. We also observed a 1.65-fold increase in plasma HIV RNA. The frequency of CD4 + T cells with inducible virus evaluated using the tat/rev limiting dilution assay was higher after 6 cycles compared to baseline. Phylogenetic analyses of HIV env sequences in a participant who developed low concentrations of HIV viremia after 6 cycles of pembrolizumab did not demonstrate clonal expansion of HIV-infected cells. These data are consistent with anti–PD-1 being able to reverse HIV latency in vivo and support the rationale for combining anti–PD-1 with other interventions to reduce the HIV reservoir.

The observation in 1981 of the emergence of Kaposi sarcoma (KS) among young men who had sex with men was one of the first harbingers of the HIV epidemic. With advances in HIV care, the incidence of HIV-associated KS (HIV+KS) has decreased over time in the United States. However, it remains a persistent malignancy among some HIV-infected populations and is one of the most common tumors in sub-Saharan Africa. Because of the relapsing and remitting nature of this cancer, patients with HIV+KS can experience significant, long-term, morbidity. Patients with severe HIV+KS may also have concurrent lymphoproliferative syndromes, malignancies, and/or infections that can contribute to mortality. Several chemotherapy agents were explored in clinical trials for HIV+KS during the early stage of the epidemic. As HIV+KS emerges with CD4 lymphopenia and immunodysregulation, T-cell–sparing options are important to consider. Here, we explore the pathogenesis of HIV+KS and the current evidence for immunotherapy and therapies that potentially target KS pathogenesis. This review provides the current landscape of therapies for HIV+KS and highlights management issues for patients with HIV and cancer.

Purpose: VEGF-A is important in the pathogenesis of Kaposi sarcoma, and bevacizumab has a response rate of 31%. We explored the combination of bevacizumab with liposomal doxorubicin in patients with Kaposi sarcoma. Patients and Methods: Patients with Kaposi sarcoma requiring systemic therapy were enrolled in one of two cohorts. Cohort 1 included patients with human immunodeficiency virus (HIV)-negative Kaposi sarcoma or with HIV-associated Kaposi sarcoma who would not be expected to respond to antiretroviral therapy (ART) alone (i.e., either stable or progressive Kaposi sarcoma on ART). Cohort 2 included all other patients with HIV-associated Kaposi sarcoma. Patients were treated with six cycles of liposomal doxorubicin with bevacizumab every 3 weeks followed by up to 11 cycles of bevacizumab alone. Results: Sixteen patients were enrolled: 10 (two HIV negative) in cohort 1 and six in cohort 2. Fourteen patients had advanced disease (AIDS Clinical Trials Group T1). Overall response rate (complete and partial responses) was 56% [80% confidence interval (CI), 38%–74%] for all patients and were similar in the two cohorts. Median progression-free survival was 6.9 months (95% CI, 4.5 months–not estimable). Grade 3 and 4 adverse events attributed to therapy included hypertension (n = 5), neutropenia (n = 6), gastrointestinal hemorrhage (n = 1), and cerebral ischemia (n = 1). There was a significant decrease in VEGF-A levels from baseline to the end of six cycles of combination therapy. Conclusions: Pegylated liposomal doxorubicin in combination with bevacizumab has activity in advanced Kaposi sarcoma, but it is unclear whether the combination yields better outcomes than liposomal doxorubicin used alone.

Because of tremendous advances in HIV care, the survival of many people living with HIV (PLWH) now approaches that of the general population. This has led to a shift in the types of malignancies diagnosed among PLWH from AIDS-defining cancers during the height of the HIV epidemic toward more non-AIDS−defining cancers and age-related incidental cancers in the last 2 decades. Despite these trends, positive cancer outcomes still lag behind patients without HIV, and many PLWH never receive appropriate cancer therapy. We explore the reasons for the epidemiologic shift that has been observed, as well as the factors that influence treatment disparities. Furthermore, several studies have demonstrated similar cancer survival rates when PLWH and certain cancers receive the same treatment as those who are HIV-negative. Among possible solutions to improve cancer outcomes include increasing the inclusion of PLWH in clinical trials, using guidelines specific for the treatment of HIV-associated malignancies, and incorporating a multidisciplinary approach to cancer management in PLWH.

Kaposi sarcoma herpesvirus (KSHV)-associated diseases (Kaposi sarcoma, multicentric Castleman disease, primary effusion lymphoma, and KSHV inflammatory cytokine syndrome) are associated with immune suppression and dysregulation and loss of KSHV-specific immunity. These diseases are most frequent in people living with HIV as well as those with primary or iatrogenic immune deficiencies. KSHV itself can modulate the immune system via viral homologs of host cytokines or downregulation of immune-surface markers altering host immune surveillance. These factors make KSHV-associated diseases prime targets for immunotherapy approaches. Several agents have been studied or are under investigation in KSHV-associated diseases, including monoclonal antibodies, immunomodulatory agents, and therapeutic cytokines. Here, we review the role of immunotherapies in KSHV-associated diseases.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent for coronavirus disease 2019 (COVID-19), encodes two proteases required for replication. The main protease (Mpro), encoded as part of two polyproteins, pp1a and pp1ab, is responsible for 11 different cleavages of these viral polyproteins to produce mature proteins required for viral replication. Mpro is therefore an attractive target for therapeutic interventions. Certain proteins in cells under oxidative stress undergo modification of reactive cysteines. We show Mpro is susceptible to glutathionylation, leading to inhibition of dimerization and activity. Activity of glutathionylated Mpro could be restored with reducing agents or glutaredoxin. Analytical studies demonstrated that glutathionylated Mpro primarily exists as a monomer and that modification of a single cysteine with glutathione is sufficient to block dimerization and inhibit its activity. Gel filtration studies as well as analytical ultracentrifugation confirmed that glutathionylated Mpro exists as a monomer. Tryptic and chymotryptic digestions of Mpro as well as experiments using a C300S Mpro mutant revealed that Cys300, which is located at the dimer interface, is a primary target of glutathionylation. Moreover, Cys300 is required for inhibition of activity upon Mpro glutathionylation. These findings indicate that Mpro dimerization and activity can be regulated through reversible glutathionylation of a non-active site cysteine, Cys300, which itself is not required for Mpro activity, and provides a novel target for the development of agents to block Mpro dimerization and activity. This feature of Mpro may have relevance to the pathophysiology of SARS-CoV-2 and related bat coronaviruses. IMPORTANCE SARS-CoV-2 is responsible for the devastating COVID-19 pandemic. Therefore, it is imperative that we learn as much as we can about the biochemistry of the coronavirus proteins to inform development of therapy. One attractive target is the main protease (Mpro), a dimeric enzyme necessary for viral replication. Most work thus far developing Mpro inhibitors has focused on the active site. Our work has revealed a regulatory mechanism for Mpro activity through glutathionylation of a cysteine (Cys300) at the dimer interface, which can occur in cells under oxidative stress. Cys300 glutathionylation inhibits Mpro activity by blocking its dimerization. This provides a novel accessible and reactive target for drug development. Moreover, this process may have implications for disease pathophysiology in humans and bats. It may be a mechanism by which SARS-CoV-2 has evolved to limit replication and avoid killing host bats when they are under oxidative stress during flight.

In Sub-Saharan Africa, the cancer burden is predicted to increase by > 85% by 2030, the largest increase worldwide. This region has a large HIV-positive population. Drug-drug interactions (DDIs) from concomitant use of multiple drugs increase the risk of drug toxicities, sub-optimal therapy, and drug resistance. With the increase in polypharmacy, involving antiretroviral (ARV), and anticancer drugs, there is a greater need for an appreciation of clinically relevant DDIs. Anticancer and ARV drugs studied in this review were from The World Health Organization's Model List of Essential Medicines 2017. We reviewed; drug package inserts, www.drugbank.ca and www.UpToDate.com, to evaluate pharmacokinetic interactions with cytochrome P450 (CYP450) and ABCB1. The DDIs between drugs were assessed using the University Of Liverpool, UK HIV Drug Interactions Checker, and the LexiComp Drug Interaction tool of www.UpToDate.com. About 70% of ARVs studied interact with CYP450, all involve CYP3A4, and 55% interact with ABCB1. About 65% of anticancer drugs interact with CYP450, 44% of which do so through CYP3A4. About 75% of anticancer drugs interact with ARV drugs, with nine absolute contraindications to concomitant therapy. There exist a substantial number of DDIs between ARV and anticancer drugs, primarily mediated through CYP450 enzymes. Dolutegravir based regimens offer the safest DDI profile for concurrent use with anticancer drugs. However, there are substantial gaps in our knowledge, and this study serves to highlight the need for additional research to better define these interactions and their effect on drug exposure, as attention to these DDIs is a relatively simple intervention that could lead to optimizing disease treatment.

BackgroundNon-Hodgkin’s lymphoma (NHL) is currently the most common malignancy among people living with HIV (PLWH) in the USA. NHL in PLWH is more frequently associated with oncogenic viruses than NHL in immunocompetent individuals and is generally associated with increased PD-1 expression and T cell exhaustion. An effective immune-based second-line approach that is less immunosuppressive than chemotherapy may decrease infection risk, improve immune control of oncogenic viruses, and ultimately allow for better lymphoma control.MethodsWe conducted a retrospective study of patients with HIV-associated lymphomas treated with pembrolizumab±pomalidomide in the HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute.ResultsWe identified 10 patients with stage IV relapsed and/or primary refractory HIV-associated NHL who were treated with pembrolizumab, an immune checkpoint inihibitor, with or without pomalidomide. Five patients had primary effusion lymphoma (PEL): one had germinal center B cell-like (GCB) diffuse large B cell lymphoma (DLBCL); two had non-GCB DLBCL; one had aggressive B cell lymphoma, not otherwise specified; and one had plasmablastic lymphoma. Six patients received pembrolizumab alone at 200 mg intravenously every 3 weeks, three received pembrolizumab 200 mg intravenously every 4 weeks plus pomalidomide 4 mg orally every day for days 1–21 of a 28-day cycle; and one sequentially received pembrolizumab alone and then pomalidomide alone. The response rate was 50% with particular benefit in gammaherpesvirus-associated tumors. The progression-free survival was 4.1 months (95% CI: 1.3 to 12.4) and overall survival was 14.7 months (95% CI: 2.96 to not reached). Three patients with PEL had leptomeningeal disease: one had a complete response and the other two had long-term disease control. There were four immune-related adverse events (irAEs), all CTCAEv5 grade 2–3; three of the four patients were able to continue receiving pembrolizumab. No irAEs occurred in patients receiving the combination of pembrolizumab and pomalidomide.ConclusionsTreatment of HIV-associated NHL with pembrolizumab with or without pomalidomide elicited responses in several subtypes of HIV-associated NHL. This approach is worth further study in PLWH and NHL.

Targeting the main protease (Mpro) of SARS-CoV-2, we identified two indole-chloropyridinyl-ester derivatives, GRL-0820 and GRL-0920, active against SARS-CoV-2, employing RNA-qPCR and immunocytochemistry and show that the two compounds exerted potent activity against SARS-CoV-2. While GRL-0820 and remdesivir blocked SARS-CoV-2 infection, viral breakthrough occurred as examined with immunocytochemistry. In contrast, GRL-0920 completely blocked the infectivity and cytopathic effect of SARS-CoV-2 without significant toxicity. Structural modeling showed that indole and chloropyridinyl of the derivatives interacted with two catalytic dyad residues of Mpro, Cys145 and His41, resulting in covalent bonding, which was verified using HPLC/MS. The present data should shed light on the development of therapeutics for COVID-19, and optimization of GRL-0920 based on the present data is essential to develop more-potent anti-SARS-CoV-2 compounds for treating COVID-19., We assessed various newly generated compounds that target the main protease (Mpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and various previously known compounds reportedly active against SARS-CoV-2, employing RNA quantitative PCR (RNA-qPCR), cytopathicity assays, and immunocytochemistry. Here, we show that two indole-chloropyridinyl-ester derivatives, GRL-0820 and GRL-0920, exerted potent activity against SARS-CoV-2 in cell-based assays performed using VeroE6 cells and TMPRSS2-overexpressing VeroE6 cells. While GRL-0820 and the nucleotide analog remdesivir blocked SARS-CoV-2 infection, viral breakthrough occurred. No significant anti-SARS-CoV-2 activity was found for several compounds reportedly active against SARS-CoV-2 such as lopinavir, nelfinavir, nitazoxanide, favipiravir, and hydroxychroloquine. In contrast, GRL-0920 exerted potent activity against SARS-CoV-2 (50% effective concentration [EC50] = 2.8 μM) and dramatically reduced the infectivity, replication, and cytopathic effect of SARS-CoV-2 without significant toxicity as examined with immunocytochemistry. Structural modeling shows that indole and chloropyridinyl of the derivatives interact with two catalytic dyad residues of Mpro, Cys145 and His41, resulting in covalent bonding, which was verified using high-performance liquid chromatography–mass spectrometry (HPLC/MS), suggesting that the indole moiety is critical for the anti-SARS-CoV-2 activity of the derivatives. GRL-0920 might serve as a potential therapeutic for coronavirus disease 2019 (COVID-19) and might be optimized to generate more-potent anti-SARS-CoV-2 compounds.

PURPOSE OF REVIEW: Immune checkpoint inhibitors targeting the programmed cell death-1 (PD-1) pathway are a class of anti-cancer immunotherapy agents changing treatment paradigms of many cancers that occur at higher rates in people living with HIV (PLWH) than in the general population. However, PLWH have been excluded from most of the initial clinical trials with these agents. RECENT FINDINGS: Two recent prospective studies of anti-PD-1 agents, along with observational studies and a meta-analysis have demonstrated acceptable safety in PLWH. Preliminary evidence indicates activity in a range of tumors and across CD4(+) T-cell counts. SUMMARY: Safety and preliminary activity data suggest monoclonal antibodies targeting PD-1 or its ligand, PD-L1, are generally appropriate for PLWH and cancers for which there are FDA-approved indications. Ongoing and future trials of anti-PD-1 and anti PD-L1 therapy alone or in combination for HIV-associated cancers may further improve outcomes for this underserved population.

Cervical cancer is the most common cancer affecting sub-Saharan African women and is prevalent among HIV-positive (HIV+) individuals. No comprehensive profiling of cancer genomes, transcriptomes or epigenomes has been performed in this population thus far. We characterized 118 tumors from Ugandan patients, of whom 72 were HIV+, and performed extended mutation analysis on an additional 89 tumors. We detected human papillomavirus (HPV)-clade-specific differences in tumor DNA methylation, promoter- and enhancer-associated histone marks, gene expression and pathway dysregulation. Changes in histone modification at HPV integration events were correlated with upregulation of nearby genes and endogenous retroviruses.

Except remdesivir, no specific antivirals for SARS-CoV-2 infection are currently available. Here, we characterize two small-molecule-compounds, named GRL-1720 and 5h, containing an indoline and indole moiety, respectively, which target the SARS-CoV-2 main protease (Mpro). We use VeroE6 cell-based assays with RNA-qPCR, cytopathic assays, and immunocytochemistry and show both compounds to block the infectivity of SARS-CoV-2 with EC50 values of 15 ± 4 and 4.2 ± 0.7 μM for GRL-1720 and 5h, respectively. Remdesivir permitted viral breakthrough at high concentrations; however, compound 5h completely blocks SARS-CoV-2 infection in vitro without viral breakthrough or detectable cytotoxicity. Combination of 5h and remdesivir exhibits synergism against SARS-CoV-2. Additional X-ray structural analysis show that 5h forms a covalent bond with Mpro and makes polar interactions with multiple active site amino acid residues. The present data suggest that 5h might serve as a lead Mpro inhibitor for the development of therapeutics for SARS-CoV-2 infection., Here, using in vitro assays and structural analysis, the authors characterize the anti-SARS-CoV-2 properties of two small molcules, showing these to bind and target the virus main protease (Mpro), and to exhibit a synergistic antiviral effect when combined with remdesivir in vitro.

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent for Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman disease (MCD). Like other herpesviruses, it has latent and lytic repertoires. However, there is evidence that some lytic genes can be directly activated by certain cellular factors. Cells undergoing endoplasmic reticulum stress express spliced X-box binding protein 1 (XBP-1s). XBP-1s is also present in large amounts in germinal center B cells. XBP-1s can activate the KSHV replication and transcription activator (RTA) and lytic replication. It can also directly activate KSHV-encoded viral interleukin-6 (vIL-6) and, thus, contribute to the pathogenesis of KSHV MCD. KSHV thymidine kinase (TK), the ORF21 gene product, can enhance the production of dTTP and is important for lytic replication. It can also phosphorylate zidovudine and ganciclovir to toxic moieties, enabling treatment of KSHV-MCD with these drugs. We show here that XBP-1s can directly activate ORF21 and that this activation is mediated primarily through two XBP-response elements (XRE) on the ORF21 promoter region. Deletion or mutation of these elements eliminated XBP-1s-induced upregulation of the promoter, and chromatin immunoprecipitation studies provide evidence that XBP-1s can bind to both XREs. Exposure of PEL cells to a chemical inducer of XBP-1s can induce ORF21 within 4 hours, and ORF21 expression in the lymph nodes of patients with KSHV-MCD is predominantly found in cells with XBP-1. Thus, XBP-1s may directly upregulate KSHV ORF21 and, thus, contribute to the pathogenesis of KSHV-MCD and the activity of zidovudine and valganciclovir in this disease. IMPORTANCE Spliced X-box binding protein 1 (XBP-1s), part of the unfolded protein response and expressed in developing germinal center B cells, can induce Kaposi’s sarcoma-associated herpesvirus (KSHV) lytic replication and directly activate viral interleukin-6 (vIL-6). We show here that XBP-1s can also directly activate KSHV ORF21, a lytic gene. ORF21 encodes KSHV thymidine kinase (TK), which increases the pool of dTTP for viral replication and enhances lytic replication. Direct activation of ORF21 by XBP-1s can enhance viral replication in germinal center B cells and contribute to the pathogenesis of KSHV multicentric Castleman disease (MCD). KSHV-MCD is characterized by systemic inflammation caused, in part, by lytic replication and overproduction of KSHV vIL-6 in XBP-1s-expressing lymph node plasmablasts. KSHV thymidine kinase can phosphorylate zidovudine and ganciclovir to toxic moieties, and direct activation of ORF21 by XBP-1s may also help explain the effectiveness of zidovudine and valganciclovir in the treatment of KSHV-MCD.

Human lysyl oxidase (LOX) is a hypoxia-responsive gene whose product catalyzes collagen crosslinking and is thought to be important in cancer metastasis and osteoarthritis. We previously demonstrated that LOX was upregulated by hypoxia inducible factor 2 (HIF-2) more strongly than hypoxia inducible 1 (HIF-1). Here, we further investigated the response of the LOX gene and LOX promoter to HIFs. LOX mRNA, measured by real time reverse transcriptase-PCR, was strongly up-regulated (almost 40-fold), by transfection of HEK-293T cells with a plasmid encoding the HIF-2α subunit of HIF-2, but only three-fold by a plasmid encoding HIF-1α. LOX protein was detectable by Western blot of cells transfected with HIF-2α, but not with HIF-1α. Analysis of a 1487 bp promoter sequence upstream of the human LOX gene revealed 9 potential hypoxia response elements (HREs). Promoter truncation allowed the mapping of two previously unidentified functional HREs, called here HRE8 and HRE7; -455 to -451 and -382 to -386 bp, respectively, upstream of the start codon for LOX. Removal or mutation of these HREs led to a substantial reduction in both HIF-1α and HIF-2α responsiveness. Also, expression of LOX was significantly inhibited by a small molecule specific HIF-2 inhibitor. In conclusion, LOX is highly responsive to HIF-2α and this is largely mediated by two previously unidentified HREs. These observations enhance our understanding of the regulation of this important gene involved in cancer and osteoarthritis, and suggest that these conditions may be targeted by HIF-2 inhibitors.

Infection by Kaposi’s sarcoma-associated herpesvirus (KSHV) is necessary for the development of Kaposi’s sarcoma (KS), which most often develops in HIV-infected individuals. KS frequently has oral manifestations and KSHV DNA can be detected in oral cells. Numerous types of cancer are associated with the alteration of microbiome including bacteria and virus. We hypothesize that oral bacterial microbiota affects or is affected by oral KS and the presence of oral cell-associated KSHV DNA. In this study, oral and blood specimens were collected from a cohort of HIV/KSHV-coinfected individuals all previously diagnosed with KS, and were classified as having oral KS with any oral cell-associated KSHV DNA status (O-KS, n = 9), no oral KS but with oral cell-associated KSHV DNA (O-KSHV, n = 10), or with neither oral KS nor oral cell-associated KSHV DNA (No KSHV, n = 10). We sequenced the hypervariable V1-V2 region of the 16S rRNA gene present in oral cell-associated DNA by next generation sequencing. The diversity, richness, relative abundance of operational taxonomic units (OTUs) and taxonomic composition of oral microbiota were analyzed and compared across the 3 studied groups. We found impoverishment of oral microbial diversity and enrichment of specific microbiota in O-KS individuals compared to O-KSHV or No KSHV individuals. These results suggest that HIV/KSHV coinfection and oral microbiota might impact one another and influence the development of oral KS., Author summary Kaposi’s sarcoma (KS) is the most common cancer occurring in HIV-infected individuals worldwide, and often involves the mouth. While infection by Kaposi’s sarcoma-associated herpesvirus (KSHV) is necessary for the development of KS, other cofactors remain unclear. In this study, we evaluated the impact of oral bacterial microbiota on the development of oral KS and the presence of oral cell-associated KSHV DNA by studying a cohort of HIV/KSHV-coinfected individuals all previously diagnosed with KS, classified as having oral KS with any oral cell-associated KSHV DNA status (O-KS), no oral KS but with oral cell-associated KSHV DNA (O-KSHV), or with neither oral KS nor oral cell-associated KSHV DNA (No KSHV). We observed impoverishment of oral microbial diversity and enrichment of specific types of microbes in O-KS individuals compared to O-KSHV or No KSHV individuals. Hence, HIV/KSHV coinfection and oral microbiota might impact one another and influence the development of oral KS.

Primary effusion lymphoma (PEL) is an aggressive HIV-associated lymphoma with a relatively poor prognosis in the era of effective HIV therapy. Kaposi sarcoma herpesvirus (KSHV) is the etiologic agent, and ∼80% of tumors are coinfected with Epstein-Barr virus (EBV). A better understanding of how KSHV-related immune dysregulation contributes to the natural history of PEL will improve outcomes. Twenty patients with PEL diagnosed between 2000 and 2013, including 19 treated with modified infusional etoposide, vincristine, and doxorubicin with cyclophosphamide and prednisone (EPOCH), were identified. We compared their clinical, virologic, and immunologic features vs 20 patients with HIV-associated diffuse large B-cell lymphoma and 19 patients with symptomatic interleukin (IL)-6 related KSHV-associated multicentric Castleman disease. Survival analyses of treated patients with PEL were then performed to identify prognostic factors and cancer-specific mortality. Compared with HIV-associated diffuse large B-cell lymphoma, PEL was associated with significant hypoalbuminemia (P < .0027), thrombocytopenia (P = .0045), and elevated IL-10 levels (P < .0001). There were no significant differences in these parameters between PEL and KSHV-associated multicentric Castleman disease. Median overall survival in treated patients with PEL was 22 months, with a plateau in survival noted after 2 years. Three-year cancer-specific survival was 47%. EBV-positive tumor status was associated with improved survival (hazard ratio, 0.27; P = .038), and elevated IL-6 level was associated with inferior survival (hazard ratio, 6.1; P = .024). Our analysis shows that IL-6 and IL-10 levels contribute to the natural history of PEL. Inflammatory cytokines and tumor EBV status are the strongest prognostic factors. Pathogenesis-directed first-line regimens are needed to improve overall survival in PEL.

Pomalidomide (Pom) is an immunomodulatory drug that has efficacy against Kaposi’s sarcoma, a tumor caused by Kaposi’s sarcoma-associated herpesvirus (KSHV). Pom also induces direct cytotoxicity in primary effusion lymphoma (PEL), a B-cell malignancy caused by KSHV, in part through downregulation of IRF4, cMyc, and CK1α as a result of its interaction with cereblon, a cellular E3 ubiquitin ligase. Additionally, Pom can reverse KSHV-induced downregulation of MHCI and co-stimulatory immune surface molecules ICAM-1 and B7-2 on PELs. Here, we show for the first time that Pom-induced increases in ICAM-1 and B7-2 on PEL cells lead to an increase in both T-cell activation and NK-mediated cytotoxicity against PEL. The increase in T-cell activation can be prevented by blocking ICAM-1 and/or B7-2 on the PEL cell surface, suggesting that both ICAM-1 and B7-2 are important for T-cell co-stimulation by PELs. To gain mechanistic insights into Pom’s effects on surface markers, we generated Pom-resistant (PomR) PEL cells, which showed about 90% reduction in cereblon protein level and only minimal changes in IRF4 and cMyc upon Pom treatment. Pom no longer upregulated ICAM-1 and B7-2 on the surface of PomR cells, nor did it increase T-cell and NK-cell activation. Cereblon-knockout cells behaved similarly to the pomR cells upon Pom-treatment, suggesting that Pom’s interaction with cereblon is necessary for these effects. Further mechanistic studies revealed PI3K signaling pathway as being important for Pom-induced increases in these molecules. These observations provide a rationale for the study of Pom as therapy in treating PEL and other KSHV-associated tumors., Author summary Primary effusion lymphoma (PEL) is an aggressive B-cell lymphoma caused by Kaposi’s sarcoma-associated herpesvirus (KSHV). KSHV encodes various genes that enable infected cells to evade recognition and elimination by the immune system. PEL cells are poorly recognized by T-cells and NK cells, partly due to KSHV-induced downregulation of immune stimulatory surface molecules ICAM-1 and B7-2. We previously found that a cereblon-binding immunomodulatory drug pomalidomide (Pom) can restore the levels of these markers on PELs. Here, we show that the increases in ICAM-1 and B7-2 induced by Pom leads to a functional increase in the recognition and killing of PELs by both T-cells and NK cells. Further, exposure of both the PEL cells and T-cells to Pom lead to an even higher T-cell stimulation providing strong evidence that Pom could help PEL patients by providing specific immune-stimulatory effect. We further perform mechanistic studies and show that Pom’s cellular binding partner cereblon as well as the PI3K pathway are important for Pom-mediated increases in these surface markers.

People living with human immunodeficiency virus (HIV) are living longer since the advent of effective combined antiretroviral therapy (cART). While cART substantially decreases the risk of developing some cancers, HIV-infected individuals remain at high risk for Kaposi sarcoma, lymphoma, and several solid tumors. Currently HIV-infected patients represent an aging group, and malignancies have become a leading cause of morbidity and mortality. Tailored cancer-prevention strategies are needed for this population. In this review we describe the etiologic agents and pathogenesis of common malignancies in the setting of HIV, as well as current evidence for cancer prevention strategies and screening programs.

Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent for Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and a subset of multicentric Castleman disease (MCD). The KSHV life cycle has two principal gene repertoires, latent and lytic. KSHV viral interleukin-6 (vIL-6), an analog of human IL-6, is usually lytic; production of vIL-6 by involved plasmablasts is a central feature of KSHV-MCD. vIL-6 also plays a role in PEL and KS. We show that a number of plasmablasts from lymph nodes of patients with KSHV-MCD express vIL-6 but not ORF45, a KSHV lytic gene. We further show that vIL-6 is directly induced by the spliced (active) X-box binding protein-1 (XBP-1s), a transcription factor activated by endoplasmic reticulum (ER) stress and differentiation of B cells in lymph nodes. The promoter region of vIL-6 contains several potential XBP-response elements (XREs), and two of these elements in particular mediate the effect of XBP-1s. Mutation of these elements abrogates the response to XBP-1s but not to the KSHV replication and transcription activator (RTA). Also, XBP-1s binds to the vIL-6 promoter in the region of these XREs. Exposure of PEL cells to a chemical inducer of XBP-1s can induce vIL-6. Patient-derived PEL tumor cells that produce vIL-6 frequently coexpress XBP-1, and immunofluorescence staining of involved KSHV-MCD lymph nodes reveals that most plasmablasts expressing vIL-6 also coexpress XBP-1. These results provide evidence that XBP-1s is a direct activator of KSHV vIL-6 and that this is an important step in the pathogenesis of KSHV-MCD and PEL. IMPORTANCE Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease (KSHV-MCD) is characterized by severe inflammatory symptoms caused by an excess of cytokines, particularly KSHV-encoded viral interleukin-6 (vIL-6) produced by lymph node plasmablasts. vIL-6 is usually a lytic gene. We show that a number of KSHV-MCD lymph node plasmablasts express vIL-6 but do not have full lytic KSHV replication. Differentiating lymph node B cells express spliced (active) X-box binding protein-1 (XBP-1s). We show that XBP-1s binds to the promoter of vIL-6 and can directly induce production of vIL-6 through X-box protein response elements on the vIL-6 promoter region. We further show that chemical inducers of XBP-1s can upregulate production of vIL-6. Finally, we show that most vIL-6-producing plasmablasts from lymph nodes of KSHV-MCD patients coexpress XBP-1s. These results demonstrate that XBP-1s can directly induce vIL-6 and provide evidence that this is a key step in the pathogenesis of KSHV-MCD and other KSHV-induced diseases.

Clusters of cases of pneumocystis pneumonia and Kaposi’s sarcoma in New York and California in men who had sex with men were early harbingers of the acquired immunodeficiency syndrome (AIDS) epidemic.(1) The syndrome was also soon noted to be associated with a high incidence of aggressive B-cell lymphomas. As the AIDS definition crystallized, Kaposi’s sarcoma, aggressive B-cell lymphomas, and invasive cervical cancer were considered to be AIDS-defining cancers when they developed in patients with human immunodeficiency virus (HIV) infection.(2) Additional cancers are now known to be associated with HIV (Table 1). The term HIV-associated cancer is used here to describe this larger group of cancers (both AIDS-defining and non–AIDS-defining cancers) that have an increased incidence among patients with HIV infection. In addition, incidental cancers also may develop in patients with HIV infection.

We examined anemia and malaria as risk factors for Kaposi sarcoma-associated herpesvirus (KSHV) seropositivity and antibody levels in a long-standing rural Ugandan cohort, in which KSHV is prevalent. Samples from 4134 children, aged 1-17 years, with a sex ratio of 1:1, and 3149 adults aged 18-103 years, 41% of whom were males, were analyzed. Among children, malaria infection was associated with higher KSHV prevalence (61% vs 41% prevalence among malaria infected and uninfected, respectively); malaria was not assessed in adults. Additionally, lower hemoglobin level was associated with an increased prevalence of KSHV seropositivity, both in children and in adults.

Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease (MCD) is a rare, polyclonal lymphoproliferative disorder characterized by flares of inflammatory symptoms, edema, cytopenias, lymphadenopathy, and splenomegaly. Diagnosis requires a lymph node biopsy. Pathogenesis is related to dysregulated inflammatory cytokines, including human and viral interleukin-6. Rituximab alone or in combination with chemotherapy, such as liposomal doxorubicin, has led to an overall survival of over 90% at 5 years. Experimental approaches to treatment include virus activated cytotoxic therapy with high-dose zidovudine and valganciclovir and targeting human interleukin-6 activity. Despite successful treatment of KSHV-MCD, patients remain at high risk for developing non-Hodgkin lymphomas.

Kaposi sarcoma (KS) herpesvirus-associated multicentric Castleman disease (KSHV-MCD) is a lymphoproliferative disorder, most commonly seen in HIV-infected patients, that has a high mortality if untreated. Concurrent KS is common. Although rituximab has reported activity in KSHV-MCD, its use is often associated with KS progression. Within a natural history study of KSHV-MCD, we prospectively evaluated rituximab 375 mg/m(2) combined with liposomal doxorubicin 20 mg/m(2) (R-Dox) every 3 weeks in 17 patients. Patients received a median of 4 cycles (range 3-9). All received antiretroviral therapy, 11 received consolidation interferon-α, and 6 received consolidation high-dose zidovudine with valganciclovir. Using NCI KSHV-MCD response criteria, major clinical and biochemical responses were attained in 94% and 88% of patients, respectively. With a median 58 months' potential follow-up, 3-year event-free survival was 69% and 3-year overall survival was 81%. During R-Dox therapy, cutaneous KS developed in 1 patient, whereas 5 of 6 patients with it had clinical improvement. R-Dox was associated with significant improvement in anemia and hypoalbuminemia. KSHV viral load, KSHV viral interleukin-6, C-reactive protein, human interleukin-6, and serum immunoglobulin free light chains decreased with therapy. R-Dox is effective in symptomatic KSHV-MCD and may be useful in patients with concurrent KS. This trial was registered at www.clinicaltrials.gov as #NCT00092222.

Antiretroviral therapy for HIV-1 infection/AIDS has significantly extended the life expectancy of HIV-1-infected individuals and reduced HIV-1 transmission at very high rates. However, certain individuals who initially achieve viral suppression to undetectable levels may eventually suffer treatment failure mainly due to adverse effects and the emergence of drug-resistant HIV-1 variants. Here, we report GRL-142, a novel HIV-1 protease inhibitor containing an unprecedented 6-5-5-ring-fused crown-like tetrahydropyranofuran, which has extremely potent activity against all HIV-1 strains examined with IC50 values of attomolar-to-picomolar concentrations, virtually no effects on cellular growth, extremely high genetic barrier against the emergence of drug-resistant variants, and favorable intracellular and central nervous system penetration. GRL-142 forms optimum polar, van der Waals, and halogen bond interactions with HIV-1 protease and strongly blocks protease dimerization, demonstrating that combined multiple optimizing elements significantly enhance molecular and atomic interactions with a target protein and generate unprecedentedly potent and practically favorable agents.

Primary effusion lymphoma (PEL) is an aggressive B-cell lymphoma with poor prognosis caused by Kaposi’s sarcoma-associated herpesvirus (KSHV). Previous studies have revealed that HIF-1α, which mediates much of the cellular response to hypoxia, plays an important role in life cycle of KSHV. KSHV infection promotes HIF-1α activity, and several KSHV genes are in turn activated by HIF-1α. In this study, we investigated the effects of knocking down HIF-1α in PELs. We observed that HIF-1α knockdown in each of two PEL lines leads to a reduction in both aerobic and anaerobic glycolysis as well as lipid biogenesis, indicating that HIF-1α is necessary for maintaining a metabolic state optimal for growth of PEL. We also found that HIF-1α suppression leads to a substantial reduction in activation of lytic KSHV genes, not only in hypoxia but also in normoxia. Moreover, HIF-1α knockdown led to a decrease in the expression of various KSHV latent genes, including LANA, vCyclin, kaposin, and miRNAs, under both normoxic and hypoxic conditions. These observations provide evidence that HIF-1α plays an important role in PEL even in normoxia. Consistent with these findings, we observed a significant inhibition of growth of PEL in normoxia upon HIF-1α suppression achieved by either HIF-1α knockdown or treatment with PX-478, a small molecule inhibitor of HIF-1α. These results offer further evidence that HIF-1α plays a critical role in the pathogenesis of PEL, and that inhibition of HIF-1α can be a potential therapeutic strategy in this disease., Author summary Kaposi’s sarcoma-associated herpesvirus (KSHV) is an oncogenic herpesvirus that causes several malignancies including primary effusion lymphoma (PEL). PEL is an aggressive B-cell lymphoma that usually develops in a hypoxic environment. There is no standard treatment for PEL and it carries a poor prognosis. Previous studies have revealed that certain KSHV-encoded genes are activated by hypoxia-inducible factor 1 (HIF-1), an intracellular factor that mediates much of the cellular response to hypoxia. KSHV in turn can upregulate HIF-1, suggesting HIF-1 might play a substantial role in PEL oncogenesis. Here, we report for the first time the effects of suppressing HIF-1α, an oxygen-sensitive subunit of HIF-1, in PEL tumor cells. We demonstrate that suppressing HIF-1α can dramatically affect the oncogenic metabolic signature of PELs, replication of KSHV, expression of KSHV-encoded oncogenes, and the growth of PEL cells. Findings presented here not only provide new insights into the role of HIF-1α in KSHV-induced tumors but also provide a rationale for using anti-HIF-1α agents as a therapeutic strategy for PEL and potentially other KSHV-associated malignancies.

Background Primary effusion lymphoma (PEL) is a Kaposi's sarcoma herpes virus (KSHV)-induced lymphoma that typically arises in body cavities of HIV-infected patients. PEL cells are often co-infected with Epstein-Barr virus (EBV). "PEL-like" lymphoma is a KSHV-unrelated lymphoma that arises in body cavities of HIV-negative patients. "PEL-like" lymphoma is sometimes EBV positive. The derivation of PEL/"PEL-like" cells is unclear. Methods Mesothelial cells were cultured from body cavity effusions of 23 patients. Cell proliferation, cytokine secretion, marker phenotypes, KSHV/EBV infection, and clonality were evaluated by standard methods. Gene expression was measured by quantitative polymerase chain reaction and immunoblotting. A mouse model of PEL (3 mice/group) was used to evaluate tumorigenicity. Results We found that the mesothelia derived from six effusions of HIV-infected patients with PEL or other KSHV-associated diseases contained rare KSHV + or EBV + mesothelial cells. After extended culture (16-17 weeks), some mesothelial cells underwent a trans-differentiation process, generating lymphoid-type CD45 + /B220 + , CD5 + , CD27 + , CD43 + , CD11c + , and CD3 - cells resembling "B1-cells," most commonly found in mouse body cavities. These "B1-like" cells were short lived. However, long-term KSHV + EBV - and EBV + KSHV - clonal cell lines emerged from mesothelial cultures from two patients that were clonally distinct from the monoclonal or polyclonal B-cell populations found in the patients' original effusions. Conclusions Mesothelial-to-lymphoid transformation is a newly identified in vitro process that generates "B1-like" cells and is associated with the emergence of long-lived KSHV or EBV-infected cell lines in KSHV-infected patients. These results identify mesothelial cultures as a source of PEL cells and lymphoid cells in humans.

Flow cytometry is utilized extensively for cellular analysis, but technical limitations have prevented its routine application for characterizing virus. The recent introduction of nanoscale fluorescence-activated cytometric cell sorting now allows analysis of individual virions. Here, we demonstrate staining and sorting of infectious HIV. Fluorescent antibodies specific for cellular molecules found on budding virions were used to label CCR5-tropic Bal HIV and CXCR4-tropic NL4.3 HIV Env-expressing pseudovirions made in THP-1 cells (monocyte/macrophage) and H9 cells (T cells), respectively. Using a flow cytometer, we resolved the stained virus beyond isotype staining and demonstrated purity and infectivity of sorted virus populations on cells with the appropriate coreceptors. We subsequently sorted infectious simian/human immunodeficiency virus from archived plasma. Recovery was approximately 0.5%, but virus present in plasma was already bound to viral-specific IgG generated in vivo, likely contributing to the low yield. Importantly, using two broadly neutralizing HIV antibodies, PG9 and VRC01, we also sorted virus from archived human plasma and analyzed the sorted populations genetically and by proteomics, identifying the quasispecies present. The ability to sort infectious HIV from clinically relevant samples provides material for detailed molecular, genetic, and proteomic analyses applicable to future design of vaccine antigens and potential development of personalized treatment regimens.

Kaposi sarcoma-associated herpesvirus (KSHV) causes several tumors and hyperproliferative disorders. Hypoxia and hypoxia-inducible factors (HIFs) activate latent and lytic KSHV genes, and several KSHV proteins increase the cellular levels of HIF. Here, we used RNA sequencing, qRT-PCR, Taqman assays, and pathway analysis to explore the miRNA and mRNA response of uninfected and KSHV-infected cells to hypoxia, to compare this with the genetic changes seen in chronic latent KSHV infection, and to explore the degree to which hypoxia and KSHV infection interact in modulating mRNA and miRNA expression. We found that the gene expression signatures for KSHV infection and hypoxia have a 34% overlap. Moreover, there were considerable similarities between the genes up-regulated by hypoxia in uninfected (SLK) and in KSHV-infected (SLKK) cells. hsa-miR-210, a HIF-target known to have pro-angiogenic and anti-apoptotic properties, was significantly up-regulated by both KSHV infection and hypoxia using Taqman assays. Interestingly, expression of KSHV-encoded miRNAs was not affected by hypoxia. These results demonstrate that KSHV harnesses a part of the hypoxic cellular response and that a substantial portion of hypoxia-induced changes in cellular gene expression are induced by KSHV infection. Therefore, targeting hypoxic pathways may be a useful way to develop therapeutic strategies for KSHV-related diseases., Author Summary Kaposi sarcoma-associated herpesvirus (KSHV) is an oncogenic herpesvirus known to cause several tumors and hyperproliferative disorders. While there has been reports of KSHV activating and increasing hypoxia-inducible factors (HIFs), this is the first report investigating and establishing the extent to which KSHV has evolved to reproduce the effects of hypoxia. We demonstrate that the cellular changes in gene expression induced by KSHV infection include many of the changes induced by hypoxia. This has substantial implications for the biology of KSHV and the pathogenesis of KSHV-associated cancers. To achieve this, we used mRNA-sequencing and small RNA-sequencing in combination with bioinformatics analysis, and orthogonal assays such as qRT-PCR and Taqman assays to determine the effects of hypoxia on miRNA and mRNA expression. We showed that not only was there a 34% overlap between the hypoxic response and KSHV infection, but also that miRNA miR-210, a HIF-target known to have anti-apoptotic, angiogenic, and oncogenic properties, was independently and additively increased by KSHV infection and hypoxia. Furthermore, we explored the effects of hypoxia on KSHV miRNAs and consistently observed that none of the KSHV miRNAs are affected by oxygen deprivation. These studies suggest that KSHV harnesses a part of the hypoxic cellular response and that a substantial portion of hypoxia-induced changes in cellular gene expression are induced by KSHV infection. Previous studies have shown that hypoxia and HIFs activate KSHV-encoded genes, including several involved in tumor formation. These findings suggest that targeting HIFs or hypoxia pathways could block this positive feedback loop between KSHV and hypoxia and thus might be a useful strategy to treat KSHV-related tumors or other diseases. We believe these are important findings with broad implication for the understanding of the biology of KSHV and other oncoviruses and the pathogenesis of KSHV-induced tumors. As such, it should be of interest to the broad community of investigators and clinicians interested in the biology of oncoviruses, virus-induced cellular changes, and the pathogenesis and therapy of virus-induced tumors.

Castleman disease (CD) comprises 3 poorly understood lymphoproliferative variants sharing several common histopathological features. Unicentric CD (UCD) is localized to a single region of lymph nodes. Multicentric CD (MCD) manifests with systemic inflammatory symptoms and organ dysfunction due to cytokine dysregulation and involves multiple lymph node regions. Human herpesvirus 8 (HHV-8) causes MCD (HHV-8-associated MCD) in immunocompromised individuals, such as HIV-infected patients. However, >50% of MCD cases are HIV and HHV-8 negative (defined as idiopathic [iMCD]). The clinical and biological behavior of CD remains poorly elucidated. Here, we analyzed the clinicopathologic features of 74 patients (43 with UCD and 31 with iMCD) and therapeutic response of 96 patients (43 with UCD and 53 with iMCD) with HIV-/HHV-8-negative CD compared with 51 HIV-/HHV-8-positive patients. Systemic inflammatory symptoms and elevated inflammatory factors were more common in iMCD patients than UCD patients. Abnormal bone marrow features were more frequent in iMCD (77.0%) than UCD (45%); the most frequent was plasmacytosis, which was seen in 3% to 30.4% of marrow cells. In the lymph nodes, higher numbers of CD3+ lymphocytes (median, 58.88 ± 20.57) and lower frequency of CD19+/CD5+ (median, 5.88 ± 6.52) were observed in iMCD patients compared with UCD patients (median CD3+ cells, 43.19 ± 17.37; median CD19+/CD5+ cells, 17.37 ± 15.80). Complete surgical resection is a better option for patients with UCD. Siltuximab had a greater proportion of complete responses and longer progression-free survival (PFS) for iMCD than rituximab. Centricity, histopathological type, and anemia significantly impacted PFS. This study reveals that CD represents a heterogeneous group of diseases with differential immunophenotypic profiling and treatment response.

This review discusses the pathogenesis and recent advances in the management of Kaposi sarcoma herpesvirus (KSHV)-associated diseases.KSHV, a gammaherpesvirus, causes several tumors and related diseases, including Kaposi sarcoma, a form of multicentric Castleman disease (KSHV-MCD), and primary effusion lymphoma. These most often develop in patients infected with human immunodeficiency virus (HIV). KSHV inflammatory cytokine syndrome (KICS) is a newly described syndrome with high mortality that has inflammatory symptoms-like MCD but not the pathologic lymph node findings. KSHV-associated diseases are often associated with dysregulated human interleukin-6, and KSHV encodes a viral interleukin-6, both of which contribute to disease pathogenesis. Treatment of HIV is important in HIV-infected patients. Strategies to prevent KSHV infection may reduce the incidence of these tumors. Pomalidomide, an immunomodulatory agent, has activity in Kaposi sarcoma. Rituximab is active in KSHV-MCD but can cause Kaposi sarcoma exacerbation; rituximab plus liposomal doxorubicin is useful to treat KSHV-MCD patients with concurrent Kaposi sarcoma.KSHV is the etiological agents of all forms of Kaposi sarcoma and several other diseases. Strategies employing immunomodulatory agents, cytokine inhibition, and targeting of KSHV-infected cells are areas of active research.

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is the causative agent of KS, an important AIDS-associated malignancy. KSHV expresses at least 18 different mature microRNAs (miRNAs). We identified interleukin-1 receptor (IL-1R)-associated kinase 1 (IRAK1) as a potential target of miR-K12-9 (miR-K9) in an array data set examining changes in cellular gene expression levels in the presence of KSHV miRNAs. Using 3′-untranslated region (3′UTR) luciferase reporter assays, we confirmed that miR-K9 and other miRNAs inhibit IRAK1 expression. In addition, IRAK1 expression is downregulated in cells transfected with miR-K9 and during de novo KSHV infection. IRAK1 is an important component of the Toll-like receptor (TLR)/IL-1R signaling cascade. The downregulation of IRAK1 by miR-K9 resulted in the decreased stimulation of NF-κB activity in endothelial cells treated with IL-1α and in B cells treated with a TLR7/8 agonist. Interestingly, miR-K9 had a greater effect on NF-κB activity than did a small interfering RNA (siRNA) targeting IRAK1 despite the more efficient downregulation of IRAK1 expression with the siRNA. We hypothesized that KSHV miRNAs may also be regulating a second component of the TLR/IL-1R signaling cascade, resulting in a stronger phenotype. Reanalysis of the array data set identified myeloid differentiation primary response protein 88 (MYD88) as an additional potential target. 3′UTR luciferase reporter assays and Western blot analysis confirmed the targeting of MYD88 by miR-K5. The presence of miR-K9 and miR-K5 inhibited the production of IL-6 and IL-8 upon the IL-1α stimulation of endothelial cells. These results demonstrate KSHV-encoded miRNAs regulating the TLR/IL-1R signaling cascade at two distinct points and suggest the importance of these pathways during viral infection.

BACKGROUND Kaposi sarcoma herpesvirus (KSHV) is the cause of Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and a form of Castleman disease (KSHV-MCD). Recently a KSHV-associated inflammatory cytokine syndrome (KICS) distinct from KSHV-MCD was reported. METHODS We prospectively characterized the clinical, laboratory, virologic and immunologic features of KICS by evaluating symptomatic adults with KSHV using a prespecified definition. These features and overall survival were compared with controls from 2 prospectively characterized human immunodeficiency virus (HIV)-infected cohorts, including 1 with KSHV coinfection. RESULTS All 10 KICS subjects were HIV infected males; 5 had HIV viral load (VL) suppressed

CD4+ Th cells are important for the induction and maintenance of antigen-specific CD8+ T cell function, so their loss or dysfunction in HIV-infected or cancer patients could reduce the patients' ability to control viral infection. Previous work in murine systems indicated that IL-15 codelivered with vaccines could overcome CD4+ Th cell deficiency for induction of functionally efficient CD8+ T cells and maintenance of viral-specific CTLs, but its efficacy in helping primary human CD8+ T cell responses is unknown. In the present study, a peptide-pulsed, DC-based human coculture ex vivo system was used to study the role of IL-15 in overcoming CD4+ Th deficiency to elicit CD8+ T cell responses in CD4-depleted PBMCs from healthy individuals and PBMCs from HIV-1-infected patients. We found that IL-15 could overcome CD4+ Th deficiency to induce primary and recall memory CD8+ T cell responses in healthy individuals. Moreover, in CD4-deficient, HIV-1-infected patients with diminished CD8+ T cell responses, IL-15 greatly enhanced CD8+ T cell responses to alloantigen. These results suggest that IL-15 may be useful in the development of therapeutic and preventive vaccines against cancers and viral infections in patients defective in CD4+ Th cell.

Peripheral blood CD27(+) B cells are reduced in HIV-1-infected individuals. In healthy individuals, the human peripheral blood CD27(+) B cell pool consists of two subsets defined by the expression, or lack thereof, of the CD45 isoform B220. We investigated the presence of circulating B220(+) and B220(-) memory B cells in HIV(+) individuals and found that the reduction in CD27(+) memory B cells occurs primarily among CD27(+)B220(-) B cells. Studies conducted using healthy controls indicate that CD27(+)B220(-) B cells have a splenic marginal zone like the immunophenotype IgM(hi)IgD(lo)CD21(+)CD23(-), express TLR9, and proliferate and secrete IgG and IgM in response to B cell-specific ODN. CD27(+)B220(+) B cells have the immunophenotype IgM(lo)IgD(hi)CD21(+)CD23(+), express activation-induced cytidine deaminase, and proliferate in response to SAC but do not secrete immunoglobulin. The AICD expression, along with CD86 expression, by CD27(+)B220(+) suggests these cells are of germinal center origin. The preferential depletion of CD27(+)B220(-) B cells mirrors alterations in spleen morphology and resident B cell populations due to HIV infection reported by other investigators and may play an important role in the defective B cell immunity against T-independent pathogens such as pneumococcus observed in HIV-1-infected individuals.

Dimerization of HIV-1 protease subunits is essential for its proteolytic activity, which plays a critical role in HIV-1 replication. Hence, the inhibition of protease dimerization represents a unique target for potential intervention of HIV-1. We developed an intermolecular fluorescence resonance energy transfer-based HIV-1-expression assay employing cyan and yellow fluorescent protein-tagged protease monomers. Using this assay, we identified non-peptidyl small molecule inhibitors of protease dimerization. These inhibitors, including darunavir and two experimental protease inhibitors, blocked protease dimerization at concentrations of as low as 0.01 microm and blocked HIV-1 replication with IC(50) values of 0.0002-0.48 microm. These agents also inhibited the proteolytic activity of mature protease. Other approved anti-HIV-1 agents examined except tipranavir, a CCR5 inhibitor, and soluble CD4 failed to block the dimerization event. Once protease monomers dimerize to become mature protease, mature protease is not dissociated by this dimerization inhibition mechanism, suggesting that these agents block dimerization at the nascent stage of protease maturation. The proteolytic activity of mature protease that managed to undergo dimerization despite the presence of these agents is likely to be inhibited by the same agents acting as conventional protease inhibitors. Such a dual inhibition mechanism should lead to highly potent inhibition of HIV-1.

Primary effusion lymphoma (PEL) is a rare B-cell lymphoma caused by Kaposi's sarcoma-associated herpesvirus (KSHV). PEL is poorly responsive to standard cytotoxic chemotherapy and portends a poor survival. Consequently, new effective treatment options are urgently needed. It is known that KSHV encodes two lytic genes, ORF36 (phosphotransferase) and KSHV ORF21 (thymidine kinase), which can phosphorylate ganciclovir and azidothymidine, respectively. Here, we have explored whether these genes can be used as therapeutic targets for PEL. PEL arises in pleural spaces and other effusions that provide a hypoxic environment. Based on Northern blot analysis, exposure of PEL cells to hypoxia up-regulated the expression of both ORF36 and ORF21. Using a newly developed nonradioactive reverse-phase high-performance liquid chromatography/mass spectrometry method to separate and quantify the phosphorylated forms of ganciclovir and azidothymidine, we found that PEL cells exposed to hypoxia produced increased amounts of the toxic triphosphates of these drugs. Moreover, we found that hypoxia increased the cell toxicity of ganciclovir and azidothymidine in PEL cells but had no significant effect on the herpesvirus-negative cell line CA46. These findings may have clinical applicability in the development of effective therapies for PEL or other KSHV-related malignancies. [Cancer Res 2007;67(14):7003–10]

Kaposi’s sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8, is the causative agent of three hyperproliferative disorders: Kaposi’s sarcoma, primary effusion lymphoma (PEL) and multicentric Castleman’s disease. During viral latency a small subset of viral genes are produced, including KSHV latency-associated nuclear antigen (LANA), which help the virus thwart cellular defense responses. We found that exposure of KSHV-infected cells to oxidative stress, or other inducers of apoptosis and caspase activation, led to processing of LANA and that this processing could be inhibited with the pan-caspase inhibitor Z-VAD-FMK. Using sequence, peptide, and mutational analysis, two caspase cleavage sites within LANA were identified: a site for caspase-3 type caspases at the N-terminus and a site for caspase-1 and-3 type caspases at the C-terminus. Using LANA expression plasmids, we demonstrated that mutation of these cleavage sites prevents caspase-1 and caspase-3 processing of LANA. This indicates that these are the principal sites that are susceptible to caspase cleavage. Using peptides spanning the identified LANA cleavage sites, we show that caspase activity can be inhibited in vitro and that a cell-permeable peptide spanning the C-terminal cleavage site could inhibit cleavage of poly (ADP-ribose) polymerase and increase viability in cells undergoing etoposide-induced apoptosis. The C-terminal peptide of LANA also inhibited interleukin-1beta (IL-1β) production from lipopolysaccharide-treated THP-1 cells by more than 50%. Furthermore, mutation of the two cleavage sites in LANA led to a significant increase in IL-1β production in transfected THP-1 cells; this provides evidence that these sites function to blunt the inflammasome, which is known to be activated in latently infected PEL cells. These results suggest that specific caspase cleavage sites in KSHV LANA function to blunt apoptosis as well as interfere with the caspase-1-mediated inflammasome, thus thwarting key cellular defense mechanisms., Author Summary Upon infecting a target cell, viruses must be able to overcome cellular defense responses to survive. Two of the most important cellular defense responses against viruses are apoptosis and the inflammasome, a component of the innate immune response. Apoptosis, a programmed cell death, functions to limit the spread of viruses by destroying the infected cell while innate immune responses control viral infections through other means. Both apoptosis and the inflammasome are mediated by caspases. However, many viruses are known to encode proteins that block, suppress or delay caspase activity following cellular infection in order to block cell death and interfere with the inflammasome. We show that LANA undergoes caspase-dependent cleavage in Kaposi’s sarcoma associated herpesvirus (KSHV)-infected cells, especially when exposed to oxidative stress. Through peptide, sequence and mutational analysis, we identified two sites for caspase cleavage in KSHV LANA, one in the N-terminal region and the other in the C-terminal region. Using synthetic peptides of these cleavage sites, we show that the C-terminal site can inhibit cleavage of poly (ADP-ribose) polymerase and enhance cellular survival. Furthermore, we demonstrate that this synthetic peptide inhibits the inflammasome response as evidenced by decreased interleukin-1beta (IL-1β) production. Mutation of these cleavage sites in LANA leads to a significant increase in the inflammasome response indicated by increased IL-1β production compared to wild-type LANA. Taken in total, these results provide evidence that these cleavage sites in LANA participate both in delaying apoptosis and blunting aspects of the innate immune response. These studies provide new insights into the mechanisms by which KSHV obviates the cellular defense responses that are activated following virus infection.

Kaposi sarcoma associated herpesvirus (KSHV), a γ2-herpesvirus, also known as human herpesvirus-8, is the etiologic agent of three virally associated tumors: Kaposi sarcoma, a plasmablastic form of multicentric Castleman disease (KSHV-MCD), and primary effusion lymphoma. These malignancies are predominantly seen in people with acquired immunodeficiencies, including acquired immunodeficiency syndrome and iatrogenic immunosuppression in the setting of organ transplantation, but can also develop in the elderly. Kaposi sarcoma (KS) is most frequent in regions with high KSHV seroprevalence, such as sub-Saharan Africa and some Mediterranean countries. In the era of combination antiviral therapy, inflammatory manifestations associated with KSHV-infection, including KSHV-MCD, a recently described KSHV-associated inflammatory cytokine syndrome and KS immune reconstitution syndrome also are increasingly appreciated. Our understanding of viral and immune mechanisms of oncogenesis continues to expand and lead to improved molecular diagnostics, as well as novel therapeutic strategies that employ immune modulatory agents, manipulations of the tumor microenvironment, virus-activated cytotoxic therapy, or agents that target interactions between specific virus-host cell signaling pathways. This review focuses on the epidemiology and advances in molecular and clinical research that reflects the current understanding of viral oncogenesis, clinical manifestations, and therapeutics for KSHV-associated tumors.

Background Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease (MCD) is a lymphoproliferative inflammatory disorder commonly associated with human immunodeficiency virus (HIV). Its presentation may be difficult to distinguish from HIV and its complications, including lymphoma. Novel imaging strategies could address these problems. Methods We prospectively characterized (18)F-fluorodeoxyglucose positron emission tomography (PET) findings in 27 patients with KSHV-MCD. Patients were imaged with disease activity and at remission with scans evaluated blind to clinical status. Symptoms, C-reactive protein level, and HIV and KSHV loads were assessed in relation to imaging findings. Results KSHV-MCD activity was associated with hypermetabolic symmetric lymphadenopathy (median maximal standardized uptake value [SUVmax], 6.0; range, 2.0-8.0) and splenomegaly (3.4; 1.2-11.0), with increased metabolism also noted in the marrow (2.1; range, 1.0-3.5) and salivary glands (3.0; range, 2.0-6.0). The (18)F-fluorodeoxyglucose PET abnormalities improved at remission, with significant SUVmax decreases in the lymph nodes (P = .004), spleen (P = .008), marrow (P = .004), and salivary glands (P = .004). Nodal SUVmax correlated with symptom severity (P = .005), C-reactive protein level (R = 0.62; P = .004), and KSHV load (R = 0.54; P = .02) but not HIV load (P = .52). Conclusions KSHV-MCD activity is associated with (18)F-FDG PET abnormalities of the lymph nodes, spleen, marrow, and salivary glands. These findings have clinical implications for the diagnosis and monitoring of KSHV-MCD and shed light on its pathobiologic mechanism.

Kaposi’s sarcoma associated herpesvirus (KSHV) causes several tumors, including primary effusion lymphoma (PEL) and Kaposi’s sarcoma (KS). Cellular and viral microRNAs (miRNAs) have been shown to play important roles in regulating gene expression. A better knowledge of the miRNA-mediated pathways affected by KSHV infection is therefore important for understanding viral infection and tumor pathogenesis. In this study, we used deep sequencing to analyze miRNA and cellular mRNA expression in a cell line with latent KSHV infection (SLKK) as compared to the uninfected SLK line. This approach revealed 153 differentially expressed human miRNAs, eight of which were independently confirmed by qRT-PCR. KSHV infection led to the dysregulation of ~15% of the human miRNA pool and most of these cellular miRNAs were down-regulated, including nearly all members of the 14q32 miRNA cluster, a genomic locus linked to cancer and that is deleted in a number of PEL cell lines. Furthermore, we identified 48 miRNAs that were associated with a total of 1,117 predicted or experimentally validated target mRNAs; of these mRNAs, a majority (73%) were inversely correlated to expression changes of their respective miRNAs, suggesting miRNA-mediated silencing mechanisms were involved in a number of these alterations. Several dysregulated miRNA-mRNA pairs may facilitate KSHV infection or tumor formation, such as up-regulated miR-708-5p, associated with a decrease in pro-apoptotic caspase-2 and leukemia inhibitory factor LIF, or down-regulated miR-409-5p, associated with an increase in the p53-inhibitor MDM2. Transfection of miRNA mimics provided further evidence that changes in miRNAs are driving some observed mRNA changes. Using filtered datasets, we also identified several canonical pathways that were significantly enriched in differentially expressed miRNA-mRNA pairs, such as the epithelial-to-mesenchymal transition and the interleukin-8 signaling pathways. Overall, our data provide a more detailed understanding of KSHV latency and guide further studies of the biological significance of these changes.

Peptides based on the amino (N) and carboxy (C)-terminal regions of human immunodeficiency virus type-1 (HIV-1) protease and on the C-terminus of p6* can inhibit HIV-1 protease activity by preventing dimerization. We developed a peptide dimerization inhibitor, P27, that included these domains and a cell permeable domain derived from HIV-1 Tat. P27 inhibited wild type (WT) and protease inhibitor (PI)-resistant HIV-1 protease (IC50: 0.23–0.32 μM). Kinetic and biochemical assays confirmed that P27 inhibits protease dimerization. Fluorescein-labeled peptide accumulated in MT-2 cells and protected acutely infected MT-2 cells from HIV-1-induced cytotoxicity (IC50: 5.1 μM). P27 also inhibited p24 accumulation from H9 and U937 cells chronically infected with WT or PI-resistant HIV-1. Immunoblot analysis on the supernatants and infected cells revealed a block in virus release by P27 rather than an inhibition of polyprotein processing. However, inhibition of p55 Gag processing by active-site inhibitors was enhanced when combined with P27, suggesting that P27 can affect protease function in maturing virions. Although P27 was rationally designed to block dimerization of the mature HIV-1 protease, the effects of P27 on HIV-1 replication may be related to partial inhibition of Gag-Pol processing leading to a disruption in virus release.

Interleukin-12 (IL-12) enhances Th1-type T-cell responses and exerts antiangiogenic effects. We initiated a phase 1 pilot study of IL-12 in 32 patients with acquired immunodeficiency syndrome (AIDS)–related Kaposi sarcoma (KS) whose KS was progressing while on antiretroviral therapy. Fifteen patients had poor prognosis T1S1 disease. IL-12 was administered subcutaneously twice weekly at doses from 100 to 625 ng/kg. The maximum tolerated dose was 500 ng/kg, and the principal toxicities were flulike symptoms, transaminase or bilirubin elevations, neutropenia, hemolytic anemia, and depression. No tumor responses were seen at the lowest dose (100 ng/kg), but 17 of 24 evaluable patients at the higher doses had partial or complete responses (response rate, 71%; 95% confidence interval, 48%-89%). Only 3 of 17 patients had a change in antiretroviral therapy before responding, and there were no significant differences between responders and nonresponders with regard to changes in CD4 counts or viral loads. Patients had increases in their serum IL-12, interferon-γ, and inducible protein-10 (IP-10) after the first dose, and increases above baseline persisted after week 4. These results provide preliminary evidence that IL-12 has substantial activity against AIDS-related KS with acceptable toxicity and warrants further investigation for this indication.

Patients with HIV infection are at an increased risk of a number of malignancies, including Kaposi's sarcoma (KS) and certain B-cell lymphomas. Most of these tumors are caused by oncogenic DNA viruses, including KS-associated herpesvirus and Epstein-Barr virus. HIV contributes to the development of these tumors through several mechanisms, including immunodeficiency, immunodysregulation, and the effects of HIV proteins such as Tat. The development of highly active antiretroviral therapy (HAART) has reduced the incidence of many HIV-associated tumors and has generally improved their responsiveness to therapy. However, the number of people living with AIDS is increasing, and it is possible that the number of AIDS-associated malignancies will rise and the pattern of tumors will change as more people live longer with HIV infection. The goal of KS therapy is long-term tumor control with minimal toxicity. HAART is an important component of this therapy, and some patients do not require other KS-specific therapies. By contrast, the goal of AIDS-related lymphoma therapy in most cases is the attainment of a complete response with curative intent, and the benefits of administering HAART during therapy must be weighed against possible disadvantages. The past decade has seen substantial improvements in the treatment of AIDS-related lymphoma, which is attributed partially to a shift in tumor type and more effective regimens. There is currently an interest in developing new therapies for HIV-associated malignancies, based on viral, vascular or other pathogenesis-based targets.

The chemokine stromal-derived factor-1α (SDF-1α) is an essential regulator of hematopoiesis, lymphocyte homing, pre-B-cell growth, and angiogenesis. As SDF-1α is constitutively expressed in many tissues, chemokine function is mostly regulated by proteolytic degradation. Human serum cleaves the 68-amino acid chemokine, SDF-1α, at both termini. The enzyme or enzymes responsible for the removal of the carboxy-terminal lysine from SDF-1α, leading to significant reduction in biologic activity, have not been identified. Using a new biochemical assay for measuring the carboxy-terminal cleavage activity, we purified from serum and plasma a peptidase that specifically removes the carboxy-terminal lysine from SDF-1α and identified it as carboxypeptidase N (CPN, also known as kininase I, arginine carboxypeptidase, and anaphylotoxin inactivator). We demonstrate that SDF-1α in serum and plasma lacks the carboxy terminal lysine, and depletion of CPN from serum and plasma significantly reduces the SDF-1α carboxypeptidase activity. Purified CPN effectively and specifically removes the carboxy-terminal lysine from SDF-1α and significantly reduces the chemokine's biologic activity as a pre-B-cell growth factor and chemoattractant. Thus, in addition to its role as a regulator of the biologic activity of kinins and anaphylatoxins, CPN is an important regulator of the biologic activity of SDF-1α by reducing the chemokine-specific activity. (Blood. 2005;105:4561-4568)