Facing up to the ongoing challenge of Kaposi's sarcoma

Role of the Killer Immunoglobulin-like Receptor and Human Leukocyte Antigen I Complex Polymorphisms in Kaposi Sarcoma-Associated Herpesvirus Infection

Background

Kaposi sarcoma, caused by the pathogen Kaposi sarcoma-associated herpesvirus (KSHV), is the most common neoplasm for patients with AIDS. Susceptibility to KSHV has been associated with several different genetic risk variants. The purpose of this study was to test whether variants of killer cell immunoglobulin-like receptors (KIRs) and their human leukocyte antigen (HLA-I) ligands influence the risk of KSHV infection.

Methods

A case-control study was performed in Xinjiang, a KSHV-endemic region of China. We recruited 299 individuals with HIV, including 123 KSHV-seropositive persons and 176 KSHV-seronegative controls. We used logistic regression and the MiDAS package to evaluate the association between KIR/HLA-I polymorphisms and KSHV infection.

Results

HLA-A*31:01, HLA-C*03:04, and HLA-C*12:03 were found to be associated with KSHV infection, with A*31:01 showing a protective effect under 3 different models (dominant: 0.30 [95% confidence interval {CI}, .08-.82], P = .031; additive: 0.30 [95% CI, .09-.80], P = .030; overdominant: 0.31 [95% CI, .09-.88], P = .042). The effect of A*31:01 might cause the variants of amino acid at HLA-A position 56, with individuals carrying an arginine having a lower KSHV infection risk. The increased homozygous KIR2DL3 was associated with a relatively high KSHV viral load (16.30% vs 41.94%, P = .010).

Conclusions

This study provides further insight into the link between HLA-I alleles and KIR genes and KSHV infection, highlighting KSHV-susceptible variants of HLA-I and KSHV replication caused by specific KIR genotype, and revealing a potential role of KIR-mediated natural killer cell activation in anti-KSHV infection.

Pulmonary Kaposi Sarcoma as an Unusual Etiology of Acute Hypoxemic Respiratory Failure in the Era of Highly Active Antiretroviral Therapy: A Case Report

Kaposi sarcoma (KS) is caused by human herpesvirus 8 (HHV-8). Epidemic KS is described in the human immunodeficiency virus (HIV) population with acquired immune deficiency syndrome (AIDS). It primarily affects the skin, but it may uncommonly disseminate to involve extracutaneous sites such as the gastrointestinal (GI) tract, liver, and lungs.

In this case report, the authors report a 26-year-old homosexual male who was admitted with acute hypoxemic respiratory failure. He was diagnosed with an HIV infection about five months before index presentation, and he was commenced on highly active antiretroviral therapy (HAART). Physical examination was remarkable for diffuse cutaneous nodules over the lower extremities, back, and oropharynx. Chest imaging revealed diffuse bilateral infiltrates, mediastinal adenopathy, and a persistent bilateral pleural effusion. Extensive diagnostic workup was negative for underlying infectious etiology. Transbronchial biopsy demonstrated proliferated spindle cells that stained positive for HHV-8 in keeping with pulmonary KS. Skin biopsies also concurred with the diagnosis of cutaneous KS. Interestingly, the cluster of differentiation 4 (CD4) count was 647 cells/mm³, and HIV viral load (VL) was 500 copies/ml. This case demonstrated an atypical natural history of pulmonary KS in an HIV patient as pulmonary and disseminated mucocutaneous KS occurred with a relatively higher CD4 count (≥500 cells/mm³). It also reminds pulmonologists and infectious disease specialists to consider pulmonary KS as a differential diagnosis of acute hypoxemic respiratory failure in HIV patients, even in the absence of other clinical and laboratory criteria that define the AIDS stage.

Mitoxantrone-Loaded Nanoparticles for Magnetically Controlled Tumor Therapy-Induction of Tumor Cell Death, Release of Danger Signals and Activation of Immune Cells

Stimulating the patient’s immune system represents a promising therapeutic strategy to fight cancer. However, low immunogenicity of the tumor cells within an immune suppressive milieu often leads to weak anti-tumor immune responses. Additionally, the immune system may be impaired by accompanying aggressive chemotherapies. We show that mitoxantrone, bound to superparamagnetic iron oxide nanoparticles (SPIONs) as the transport system, can be magnetically accumulated in adherent HT-29 colon carcinoma cells, thereby inducing the same cell death phenotype as its soluble counterpart, a chemotherapeutic agent and prototypic inductor of immunogenic cell death. The nanoparticle-loaded drug induces cell cycle stop, apoptosis and secondary necrosis in a dose- and time-dependent manner comparable to the free drug. Cell death was accompanied by the release of interleukin-8 and damage-associated molecular patterns (DAMPs) such as HSP70 and ATP, which fostered chemotactic migration of monocytes and maturation of dendritic cells. We furthermore ensured absence of endotoxin contaminations and compatibility with erythrocytes and platelets and investigated the influence on plasma coagulation in vitro. Summarizing, with magnetic enrichment, mitoxantrone can be accumulated at the desired place, sparing healthy peripheral cells and tissues, such as immune cells. Conserving immune competence in cancer patients in the future might allow combined therapeutic approaches with immune therapies (e.g., checkpoint inhibitors).

Association Between Immunoglobulin E Levels and Kaposi Sarcoma in African Adults With Human Immunodeficiency Virus Infection

It has been demonstrated that activated mast cells (MCs) are enriched in Kaposi sarcoma (KS) tumors and contribute to the inflammatory microenvironment. Mechanisms driving MC activation, however, are incompletely understood. We sought to understand whether immunoglobulin E (IgE), a potent activator of MCs, was associated with KS incidence and severity. In a cross-sectional study of untreated human immunodeficiency virus (HIV)-infected adults with or without KS in Uganda, we found that patients with KS had higher plasma IgE levels than those without KS. After adjustment for age, sex, CD4+ T-cell count, and HIV RNA levels, there was a dose-response relationship between plasma IgE levels and the presence and severity of KS. Higher eosinophil counts were also associated with IgE levels, and plasma interleukin 33 concentrations were higher in individuals with KS. These findings suggest that IgE-driven atopic inflammation may contribute the pathogenesis of KS. Therapies targeting IgE-mediated MC activation thus might represent a novel approach for treatment or prevention of KS.

HIV-1 Tat Interacts with a Kaposi's Sarcoma-Associated Herpesvirus Reactivation-Upregulated Antiangiogenic Long Noncoding RNA, LINC00313, and Antagonizes Its Function

KS is a prevalent tumor associated with infections with two distinct viruses, KSHV and HIV. Since KSHV and HIV infect distinct cell types, the virus-virus interaction associated with KS formation has focused on secretory factors. HIV Tat is a well-known RNA binding protein secreted by HIV. Here, we revealed LINC00313, an lncRNA upregulated during KSHV lytic reactivation, as a novel HIV Tat-interacting lncRNA that potentially mediates HIV-KSHV interactions. We found that LINC00313 can repress endothelial cell angiogenesis-related properties potentially by interacting with chromatin remodeling complex PRC2 and downregulation of cell migration-regulating genes. An interaction between HIV Tat and LINC00313 contributed to the dissociation of PRC2 from LINC00313 and the disinhibition of LINC00313-induced repression of cell motility. Given that lncRNAs are emerging as key players in tissue physiology and disease progression, including cancer, the mechanism identified in this study may help decipher the mechanisms underlying KS pathogenesis induced by HIV and KSHV coinfection.

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi’s sarcoma (KS), an AIDS-defining cancer with abnormal angiogenesis. The high incidence of KS in human immunodeficiency virus (HIV)-infected AIDS patients has been ascribed to an interaction between HIV type 1 (HIV-1) and KSHV, focusing on secretory proteins. The HIV-1 secreted protein HIV Tat has been found to synergize with KSHV lytic proteins to induce angiogenesis. However, the impact and underlying mechanisms of HIV Tat in KSHV-infected endothelial cells undergoing viral lytic reactivation remain unclear. Here, we identified LINC00313 as a novel KSHV reactivation-activated long noncoding RNA (lncRNA) that interacts with HIV Tat. We found that LINC00313 overexpression inhibits cell migration, invasion, and tube formation, and this suppressive effect was relieved by HIV Tat. In addition, LINC00313 bound to polycomb repressive complex 2 (PRC2) complex components, and this interaction was disrupted by HIV Tat, suggesting that LINC00313 may mediate transcription repression through recruitment of PRC2 and that HIV Tat alleviates repression through disruption of this association. This notion was further supported by bioinformatics analysis of transcriptome profiles in LINC00313 overexpression combined with HIV Tat treatment. Ingenuity Pathway Analysis (IPA) showed that LINC00313 overexpression negatively regulates cell movement and migration pathways, and enrichment of these pathways was absent in the presence of HIV Tat. Collectively, our results illustrate that an angiogenic repressive lncRNA, LINC00313, which is upregulated during KSHV reactivation, interacts with HIV Tat to promote endothelial cell motility. These results demonstrate that an lncRNA serves as a novel connector in HIV-KSHV interactions.

IMPORTANCE KS is a prevalent tumor associated with infections with two distinct viruses, KSHV and HIV. Since KSHV and HIV infect distinct cell types, the virus-virus interaction associated with KS formation has focused on secretory factors. HIV Tat is a well-known RNA binding protein secreted by HIV. Here, we revealed LINC00313, an lncRNA upregulated during KSHV lytic reactivation, as a novel HIV Tat-interacting lncRNA that potentially mediates HIV-KSHV interactions. We found that LINC00313 can repress endothelial cell angiogenesis-related properties potentially by interacting with chromatin remodeling complex PRC2 and downregulation of cell migration-regulating genes. An interaction between HIV Tat and LINC00313 contributed to the dissociation of PRC2 from LINC00313 and the disinhibition of LINC00313-induced repression of cell motility. Given that lncRNAs are emerging as key players in tissue physiology and disease progression, including cancer, the mechanism identified in this study may help decipher the mechanisms underlying KS pathogenesis induced by HIV and KSHV coinfection.

Impact of Protease Inhibitors on HIV-Associated Kaposi Sarcoma Incidence: A Systematic Review

BACKGROUND

Protease inhibitors (PIs) may inhibit Kaposi sarcoma (KS) carcinogenesis. However, PI-based antiretroviral therapy (ART) is rarely a first-line choice in people living with HIV (PLWH) because of cost and toxicities. This is the first systematic review to assess KS incidence stratified by ART type.

METHODS

We searched PubMed to identify original, full research reports of KS incidence in ART-treated adult PLWH, stratified by ART class, published between 1996 and 2017. For overlapping cohorts, we included only the most recent study and supplemented data with earlier relevant analyses. We described study design, sociodemographic characteristics, statistical adjustment factors, and KS incidence.

RESULTS

We identified 3 unique retrospective cohort studies, and supplemented one of the studies with results from 6 previous subgroup reports, which included 242,309 PLWH and 3570 incident KS cases. Overall, KS crude incidence decreased by a factor of 10 between untreated and ART-treated PLWH; CD4-adjusted KS incidence decreased by ∼50%, with either non-nucleoside reverse transcriptase inhibitor- or PI-based ART. A single study measured a cumulative dose-/time-dependent effect of ART, which reported a relative risk reduction in only the cohort receiving boosted PI-based ART. Other studies defined ART categories by first-line therapy only.

CONCLUSIONS

The risk of incident KS was significantly reduced, regardless of ART class even after adjusting for CD4 count. The quality of evidence (ie, most studies categorizing users by first-line ART) does not permit KS risk reduction comparisons across ART types. Given the limited number and retrospective nature of these studies, prospective data are indicated.

Gammaherpesvirus entry and fusion: A tale how two human pathogenic viruses enter their host cells

The prototypical human γ-herpesviruses Epstein-Barr virus (EBV) and Kaposi Sarcoma-associated herpesvirus (KSHV) are involved in the development of malignancies. Like all herpesviruses, they share the establishment of latency, the typical architecture, and the conserved fusion machinery to initiate infection. The fusion machinery reflects virus-specific adaptations due to the requirements of the respective herpesvirus. For example, EBV evolved a tropism switch involving either the B- or epithelial cell-tropism complexes to activate fusion driven by gB. Most of the EBV entry proteins and their cellular receptors have been crystallized providing molecular details of the initial steps of infection. For KSHV, a variety of entry and binding receptors has also been reported but the mechanism how receptor binding activates gB-driven fusion is not as well understood as that for EBV. However, the downstream signaling pathways that promote the early steps of KSHV entry are well described. This review summarizes the current knowledge of the key players involved in EBV and KSHV entry and the cell-type specific mechanisms that allow infection of a wide variety of cell types.

Kaposi Sarcoma Updates

Kaposi sarcoma (KS) is an angioproliferative mesenchymal neoplasm caused by Kaposi sarcoma-related herpesvirus. This review outlines our current understanding of the epidemiology, pathogenesis, clinical presentation, and staging for this disease. Recent research has informed a more comprehensive understanding of the epidemiology of KS in the post-antiretroviral therapy era, and highlights the continued need to better characterize the African endemic subtype. Advances in clinical oncology, including checkpoint inhibitors and new skin-directed therapies, have translated into exciting new developments for the future of KS treatment options.

Molecular Biology of KSHV in Relation to HIV/AIDS-Associated Oncogenesis

Discovered in 1994, Kaposi's sarcoma-associated herpesvirus (KSHV) has been associated with four human malignancies including Kaposi's sarcoma, primary effusion lymphoma, a subset of multicentric Castleman's disease, and KSHV inflammatory cytokine syndrome. These malignancies mostly occur in immunocompromised patients including patients with acquired immunodeficiency syndrome and often cause significant mortality because of the lack of effective therapies. Significant progresses have been made to understand the molecular basis of KSHV infection and KSHV-induced oncogenesis in the last two decades. This chapter provides an update on the recent advancements focusing on the molecular events of KSHV primary infection, the mechanisms regulating KSHV life cycle, innate and adaptive immunity, mechanism of KSHV-induced tumorigenesis and inflammation, and metabolic reprogramming in KSHV infection and KSHV-transformed cells.

Tonsil histopathology in HIV-infected versus HIV-uninfected adults

BACKGROUND

The relationship between HIV and tonsil malignancy has not been fully investigated and established. Both of these diseases prominently feature in the Otorhinolaryngology clinics.

OBJECTIVE

There is minimal data available on the histopathology of tonsillectomy specimens in the HIV-infected population. This retrospective review compared tonsil histopathology between HIV-infected and HIV-uninfected patients.

METHODS

Of the 319 adult patients undergoing tonsillectomy (01 July 2005 to 30 June 2015), HIV results were available for 160. The histological findings were compared in the HIV-infected and HIV-uninfected subgroups. The effects of age, HIV status and CD4 count on the risk of malignancy were determined.

RESULTS

There were 86 patients who were HIV-infected and 74 were uninfected. Reactive lymphoid hyperplasia was the most common diagnosis in both groups (77%). Malignancies were diagnosed in eight HIV-infected and six HIV-uninfected patients, an insignificant difference.

CONCLUSION

The majority of patients undergoing tonsillectomy had benign conditions. HIV status does not appear to be a specific risk factor for tonsil malignancies, but advanced age may be.

Ribonucleotide Reductase Inhibitor 3-AP Induces Oncogenic Virus Infected Cell Death and Represses Tumor Growth

Kaposi's Sarcoma-associated Herpesvirus (KSHV) is the etiologic agent of several human malignancies, particularly Kaposi's Sarcoma (KS), which preferentially arise in immunocompromised patients such as HIV+ subpopulation while still lacking of effective therapeutic options. We recently found that the ribonucleotide reductase (RR) subunit M2 is potentially regulated by the key oncogenic HGF/c-MET pathway in KSHV-related lymphoma cells. One of RR inhibitor, 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP) effectively induced apoptosis of KSHV+ lymphomas and suppressed tumor progression in vivo. In the current study, we found that 3-AP treatment selectively inhibited the proliferation of KSHV-infected endothelial cells, the major cellular components of KS, through inducing DNA damage, reducing the levels of intracellular iron and reactive oxygen species (ROS) and increasing viral lytic gene expression. By using a KS-like nude mouse model, we found that 3-AP treatment significantly suppressed KSHV induced tumorigenesis in vivo. Taken together, our data demonstrate targeting RR by 3-AP may represent a promising strategy for improving the treatment of KS in future.

Decreased levels of the serum inflammatory biomarkers, sGP130, IL-6, sCRP and BAFF, are associated with increased likelihood of AIDS related Kaposi's sarcoma in men who have sex with men

AIDS-related Kaposi’s sarcoma (AIDS-KS) risk remains substantially elevated compared with the general population, even among patients who receive effective combination antiretroviral therapy. This study investigated the role of inflammatory and immune activating biomarkers in AIDS-KS in men who have sex with men in the Multicenter AIDS Cohort study between 1984 and 2010. Concentrations of 24 serum biomarkers; IL-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, sGP130, sIL-2Rα, sIL-6R, eotaxin, MCP-1, MCP4, MIP 1β, TARC, BLC-BCA1, IP-10, GM-CSF, IFN-γ, BAFF, sCD14, CD27, sTNFR-2, sCRP, and TNF-α were tested longitudinally in 1,501 men. The concentrations of each biomarker were compared between AIDS-KS cases and controls at multiple time points, 0–1 years, 1–2 years, 2–3 year, 3–5 years and over 5 years, prior to KS diagnosis or study termination, using univariate non-parametric Kruskal-Wallis tests and logistic regression, adjusted for HBV and HCV co-infection, race/ethnicity, age at last visit, education, smoking and CD4+ cell count. In univariate analyses, concentrations of four markers were consistently higher in cases; sIL-2Rα, IP-10, sTNFR-2, MCP-1, and five were higher in controls; GM-CSF, IL-6, MIP-1β, sCRP, sGP130. In the adjusted models concentrations of four markers were significantly inversely associated with AIDS-KS risk including sGP130 (OR=0.14, 95% CI = 0.03–0.73, BAFF (OR=0.60, 95% CI =0.16–0.90), sCRP (OR=0.61, 95% CI = 0.43–0.87) and IL-6 (OR=0.51, 95% CI = 0.35–0.76). These results support a role for markers of immune activation and inflammation in AIDS-KS and may highlight pathways to be targeted for risk stratification or therapeutics.

BALB/c mice immunized with a combination of virus-like particles incorporating Kaposi sarcoma-associated herpesvirus (KSHV) envelope glycoproteins gpK8.1, gB, and gH/gL induced comparable serum neutralizing antibody activity to UV-inactivated KSHV

Infection with Kaposi sarcoma-associated herpesvirus (KSHV) is estimated to account for over 44,000 new cases of Kaposi sarcoma annually, with 84% occurring in Africa, where the virus is endemic. To date, there is no prophylactic vaccine against KSHV. KSHV gpK8.1, gB, and gH/gL glycoproteins, implicated in the virus entry into host cells, are attractive vaccine targets for eliciting potent neutralizing antibodies (nAbs) against virus infection. We incorporated gpK8.1, gB, or gH/gL on the surface of virus-like particles (VLPs) and characterized these VLPs for their composition, size, and functionality. To determine which viral glycoprotein(s) elicit the most effective serum-nAbs, we immunized BALB/c mice with gpK8.1, gB, or gH/gL VLPs individually or in combination. Neutralizing antibody assay revealed that sera from mice immunized with the VLPs inhibited KSHV infection of HEK-293 cells in a dose-dependent manner. As a single immunogen, gpK8.1 VLPs stimulated comparable nAb activity to that of UV-inactivated KSHV (UV-KSHV). In contrast, UV-KSHV stimulated higher titers of nAb compared to gB (p = 0.0316) or gH/gL (p = 0.0486). Mice immunized with the combination of gB and gH/gL VLPs had a better nAb response than those immunized with either gB (p = 0.0268), or gH/gL (p = 0.0397) as single VLP immunogens. Immunization with any VLP combination stimulated comparable nAb activity to UV-KSHV serum. Our data provide the first evidence that KSHV gpK8.1, gB, and gH/gL glycoproteins can be incorporated onto the surface of VLPs and used as prophylactic vaccine candidates, with potential to prevent KSHV infection.

SIRT1-mediated downregulation of p27Kip1 is essential for overcoming contact inhibition of Kaposi's sarcoma-associated herpesvirus transformed cells

Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic virus associated with Kaposi's sarcoma (KS), a malignancy commonly found in AIDS patients. Despite intensive studies in the last two decades, the mechanism of KSHV-induced cellular transformation and tumorigenesis remains unclear. In this study, we found that the expression of SIRT1, a metabolic sensor, was upregulated in a variety of KSHV-infected cells. In a model of KSHV-induced cellular transformation, SIRT1 knockdown with shRNAs or knockout by CRISPR/Cas9 gene editing dramatically suppressed cell proliferation and colony formation in soft agar of KSHV-transformed cells by inducing cell cycle arrest and contact inhibition. SIRT1 knockdown or knockout induced the expression of cyclin-dependent kinase inhibitor 1B (p27^Kip1). Consequently, p27 knockdown rescued the inhibitory effect of SIRT1 knockdown or knockout on cell proliferation and colony formation. Furthermore, treatment of KSHV-transformed cells with a SIRT1 inhibitor, nicotinamide (NAM), had the same effect as SIRT1 knockdown and knockout. NAM significantly inhibited cell proliferation in culture and colony formation in soft agar, and induced cell cycle arrest. Significantly, NAM inhibited the progression of tumors and extended the survival of mice in a KSHV-induced tumor model. Collectively, these results demonstrate that SIRT1 suppression of p27 is required for KSHV-induced tumorigenesis and identify a potential therapeutic target for KS.

Therapeutic Outcomes in AIDS-Associated Kaposi's Sarcoma Patients on Antiretroviral Therapy Treated with Chemotherapy at Two Tertiary Hospitals in Lusaka, Zambia

The incidence of HIV-associated Kaposi's sarcoma (KS) remains high in Zambia in the antiretroviral therapy era. The most efficacious treatment regimen for KS has yet to be established. In both developed and developing countries, treatment regimens have had limited efficacy. Late presentation in Africa affects therapeutic outcomes.

OBJECTIVE

The aim of this study was to determine therapeutic outcomes of epidemic KS patients on combination antiretroviral therapy (cART) after completion of six cycles of Adriamycin, Bleomycin, and Vincristine (ABV) chemotherapy.

METHODS

This was a descriptive cross-sectional study. Study participants were drawn from a study database of confirmed incident KS patients seen at the Skin Clinic of the University Teaching Hospitals (UTH) during the period between August, 2015 and September, 2016.

RESULTS

Of the 38 successfully recruited study participants, a complete response was documented in 18 (47%) after 6 cycles of ABV whereas 20 (53%) experienced a partial response. KS recurrence was observed in 8 (44%) of the individuals that experienced an initial complete response. At the time of the study, clinical assessment revealed that KS lesions had completely regressed in 21 (55%) of all the patients.

CONCLUSION

ABV chemotherapy appears ineffective in long-term resolution of epidemic KS patients on ART. Recurrence rates are high after chemotherapy in patients that experience initially favorable responses to treatment. There is a need to diagnose KS earlier, and to develop more efficacious treatment options in order to reduce recurrence rates for epidemic KS.

Association of CD4+ T-cell Count, HIV-1 RNA Viral Load, and Antiretroviral Therapy With Kaposi Sarcoma Risk Among HIV-infected Persons in the United States and Canada

BACKGROUND

Kaposi sarcoma (KS) remains common among HIV-infected persons. To better understand KS etiology and to help target prevention efforts, we comprehensively examined a variety of CD4 T-cell count and HIV-1 RNA viral load (VL) measures, as well as antiretroviral therapy (ART) use, to determine independent predictors of KS risk.

SETTING

North American AIDS Cohort Collaboration on Research and Design.

METHODS

We followed HIV-infected persons during 1996-2009 from 18 cohorts. We used time-updated Cox regression to model relationships between KS risk and recent, lagged, trajectory, and cumulative CD4 count or VL measures, as well as ART use. We used Akaike's information criterion and global P values to derive a final model.

RESULTS

In separate models, the relationship between each measure and KS risk was highly significant (P < 0.0001). Our final mutually adjusted model included recent CD4 count [hazard ratio (HR) for <50 vs. ≥500 cells/μL = 12.4; 95% confidence interval (CI): 6.5 to 23.8], recent VL (HR for ≥100,000 vs. ≤500 copies/mL = 3.8; 95% CI: 2.0 to 7.3), and cumulative (time-weighted mean) VL (HR for ≥100,000 vs. ≤500 copies/mL = 2.5; 95% CI: 1.0 to 5.9). Each P-trend was <0.0001. After adjusting for these measures, we did not detect an independent association between ART use and KS risk.

CONCLUSIONS

Our results suggested a multifactorial etiology for KS, with early and late phases of development. The cumulative VL effect suggested that controlling HIV replication promptly after HIV diagnosis is important for KS prevention. We observed no evidence for direct anti-KS activity of ART, independent of CD4 count and VL.

An In Vitro Model for Studying Cellular Transformation by Kaposi Sarcoma Herpesvirus

Kaposi sarcoma (KS) is an unusual tumor composed of proliferating spindle cells that is initiated by infection of endothelial cells (EC) with KSHV, and develops most often in the setting of immunosuppression. Despite decades of research, optimal treatment of KS remains poorly defined and clinical outcomes are especially unfavorable in resource-limited settings. KS lesions are driven by pathological angiogenesis, chronic inflammation, and oncogenesis, and various in vitro cell culture models have been developed to study these processes. KS arises from KSHV-infected cells of endothelial origin, so EC-lineage cells provide the most appropriate in vitro surrogates of the spindle cell precursor. However, because EC have a limited in vitro lifespan, and as the oncogenic mechanisms employed by KSHV are less efficient than those of other tumorigenic viruses, it has been difficult to assess the processes of transformation in primary or telomerase-immortalized EC. Therefore, a novel EC-based culture model was developed that readily supports transformation following infection with KSHV. Ectopic expression of the E6 and E7 genes of human papillomavirus type 16 allows for extended culture of age- and passage-matched mock- and KSHV-infected EC and supports the development of a truly transformed (i.e., tumorigenic) phenotype in infected cell cultures. This tractable and highly reproducible model of KS has facilitated the discovery of several essential signaling pathways with high potential for translation into clinical settings.

Diagnosis and Treatment of Kaposi Sarcoma

Kaposi sarcoma (KS) is the most common neoplasm of people living with HIV today. In Sub-Saharan Africa, KS is among the most common cancers in men, overall. Not only HIV-positive individuals present with KS; any immune compromised person infected with KS-associated herpesvirus (KSHV) or human herpesvirus 8 is at risk: the elderly, children in KSHV-endemic areas, and transplant recipients. KS diagnosis is based on detection of the viral protein latency-associated nuclear antigen (LANA) in the biopsy, but not all cases of KS are the same or will respond to the same therapy. Standard KS therapy has not changed in 20 years, but newer modalities are on the horizon and will be discussed.

Programmed death ligand 1 (PD-L1) expression influences the immune-tolerogenic microenvironment in antiretroviral therapy-refractory Kaposi's sarcoma: A pilot study

Upregulation of programmed death ligand 1 (PD-L1) is a mechanism of immune escape utilized by a variety of tumors. PD-L1 expression in tumor cells or in the surrounding infiltrate correlates with clinical responsiveness to novel therapies targeting the PD-1/PD-L1 immune checkpoint. In the context of HIV-1 infection, Kaposi's sarcoma (KS) is largely responsive to restoration of immunity following combination antiretroviral therapy (cART), but there is a subset that is not. We hypothesized that this subset of cART-refractory KS may utilize the PD-L1 pathway of immune escape. We found that PD-L1 expressing KS had a denser CD8⁺ T cell (p = 0.03) and PD-L1 positive macrophage peritumoral infiltrate (p = 0.04) to suggest the involvement of PD-L1 in shaping an immune-tolerogenic microenvironment in cART-refractory KS. The presence of PD-L1 expression in association with immune-infiltrating cells provides rationale for the clinical development PD-1/PD-L1-targeted checkpoint inhibitors in cART-refractory KS.

Role of heme oxygenase-1 in the pathogenesis and tumorigenicity of Kaposi's sarcoma-associated herpesvirus

Kaposi's Sarcoma-associated Herpesvirus (KSHV) is the etiologic agent of several malignancies, including Kaposi's Sarcoma (KS), which preferentially arise in immunocompromised patients such as HIV+ subpopulation and lack effective therapeutic options. Heme oxygenase-1 (HO-1) has been reported as an important regulator of endothelial cell cycle control, proliferation and angiogenesis. HO-1 has also been found to be highly expressed in KSHV-infected endothelial cells and oral AIDS-KS lesions. We previously demonstrate that the multifunctional glycoprotein CD147 is required for KSHV/LANA-induced endothelial cell invasiveness. During the identification of CD147 controlled downstream genes by microarray analysis, we found that the expression of HO-1 is significantly elevated in both CD147-overexpressing and KSHV-infected HUVEC cells when compared to control cells. In the current study, we further identify the regulation of HO-1 expression and mediated cellular functions by both CD147 and KSHV-encoded LANA proteins. Targeting HO-1 by either RNAi or the chemical inhibitor, SnPP, effectively induces cell death of KSHV-infected endothelial cells (the major cellular components of KS) through DNA damage and necrosis process. By using a KS-like nude mouse model, we found that SnPP treatment significantly suppressed KSHV-induced tumorigenesis in vivo. Taken together, our data demonstrate the important role of HO-1 in the pathogenesis and tumorigenesis of KSHV-infected endothelial cells, the underlying regulatory mechanisms for HO-1 expression and targeting HO-1 may represent a promising therapeutic strategy against KSHV-related malignancies.

Global burden of cancers attributable to infections in 2012: a synthetic analysis

BACKGROUND

Infections with certain viruses, bacteria, and parasites are strong risk factors for specific cancers. As new cancer statistics and epidemiological findings have accumulated in the past 5 years, we aimed to assess the causal involvement of the main carcinogenic agents in different cancer types for the year 2012.

METHODS

We considered ten infectious agents classified as carcinogenic to human beings by the International Agency for Research on Cancer. We calculated the number of new cancer cases in 2012 attributable to infections by country, by combining cancer incidence estimates (from GLOBOCAN 2012) with estimates of attributable fraction (AF) for the infectious agents. AF estimates were calculated from the prevalence of infection in cancer cases and the relative risk for the infection (for some sites). Estimates of infection prevalence, relative risk, and corresponding 95% CIs for AF were obtained from systematic reviews and pooled analyses.

FINDINGS

Of 14 million new cancer cases in 2012, 2·2 million (15·4%) were attributable to carcinogenic infections. The most important infectious agents worldwide were Helicobacter pylori (770 000 cases), human papillomavirus (640 000), hepatitis B virus (420 000), hepatitis C virus (170 000), and Epstein-Barr virus (120 000). Kaposi's sarcoma was the second largest contributor to the cancer burden in sub-Saharan Africa. The AFs for infection varied by country and development status-from less than 5% in the USA, Canada, Australia, New Zealand, and some countries in western and northern Europe to more than 50% in some countries in sub-Saharan Africa.

INTERPRETATION

A large potential exists for reducing the burden of cancer caused by infections. Socioeconomic development is associated with a decrease in infection-associated cancers; however, to reduce the incidence of these cancers without delay, population-based vaccination and screen-and-treat programmes should be made accessible and available.

FUNDING

Fondation de France.