Cytomegalovirus Infection in Cardiovascular Diseases

Human herpesvirus reactivation and its potential role in the pathogenesis of post-acute sequelae of SARS-CoV-2 infection

The emergence of SARS-CoV-2 has precipitated a global pandemic with substantial long-term health implications, including the condition known as post-acute sequelae of SARS-CoV-2 infection (PASC), commonly referred to as Long COVID. PASC is marked by persistent symptoms such as fatigue, neurological issues, and autonomic dysfunction that persist for months beyond the acute phase of COVID-19. This review examines the potential role of herpesvirus reactivation, specifically Epstein-Barr virus (EBV) and cytomegalovirus (CMV), in the pathogenesis of PASC. Elevated antibody titers and specific T cell responses suggest recent herpesvirus reactivation in some PASC patients, although viremia is not consistently detected. SARS-CoV-2 exhibits endothelial trophism, directly affecting the vascular endothelium and contributing to microvascular pathologies. These pathologies are significant in PASC, where microvascular dysfunction may underlie various chronic symptoms. Similarly, herpesviruses like CMV also exhibit endothelial trophism, which may exacerbate endothelial damage when reactivated. Evidence suggests that EBV and CMV reactivation could indirectly contribute to the immune dysregulation, immunosenescence, and autoimmune responses observed in PASC. Additionally, EBV may play a role in the genesis of neurological symptoms through creating mitochondrial dysfunction, though direct confirmation remains elusive. The reviewed evidence suggests that while herpesviruses may not play a direct role in the pathogenesis of PASC, their potential indirect effects, especially in the context of endothelial involvement, warrant further investigation.

New Directions in Infection-Associated Ischemic Stroke

The relationship between infections and stroke has not been fully characterized, probably delaying the development of specific treatments. This narrative review addresses mechanisms of stroke linked to infections, including hypercoagulability, endothelial dysfunction, vasculitis, and impaired thrombolysis. SARS-CoV-2, the virus that causes COVID-19, may promote the development of stroke, which may represent its most severe neurological complication. The development of specific therapies for infection-associated stroke remains a profound challenge. Perhaps the most important remaining issue is the distinction between infections that trigger a stroke versus infections that are truly incidental. This distinction likely requires the establishment of appropriate biomarkers, candidates of which are elevated levels of fibrin D-dimer and anticardiolipin/antiphospholipid antibodies. These candidate biomarkers might have potential use in identifying pathogenic infections preceding stroke, which is a precursor to establishing specific therapies for this syndrome.

Cytomegalovirus-positive Posner-Schlossman syndrome: to compare differences in retinal vessel area density between the affected and non-affected eye using optical coherence tomography angiography

PURPOSE

To analyse differences in the retinal microvasculature in eyes with cytomegalovirus (CMV)-positive Posner-Schlossman syndrome (PSS) compared to the non-affected eyes using optical coherence tomography angiography (OCTA).

METHODS

In this monocentric, observational prospective case series, 25 patients with unilateral CMV-positive PSS were included. We compared the vessel area densities (VAD) in the macula, optic disc, and peripapillary region in PSS-affected and non-affected eyes using OCTA. We compared the visual fields (VF) of the affected and healthy eyes of each patient. The mean deviation (MD) of the VF was analysed together with the retinal nerve fibre layer (RNFL) thickness to evaluate the strength of correlation with the VAD parameters.

RESULTS

The VAD of the peripapillary superficial vascular complex (SVC) is significantly reduced in CMV-positive PSS-affected eyes (46.1 ± 9.3% versus 50.1 ± 6.3%, p = 0.008, adjusted p = 0.048). The VAD of the deeper macular, papillary, and peripapillary layers showed no differences between the affected and non-affected eyes. The mean deviation and the retinal nerve fibre layer thickness had correlations with the VAD of the macula (r = 0.451, p = 0.001, r = 0.553, p < 0.001), the peripapillary SCV (r = 0.430, p = 0.002, r = 0.723, p < 0.001), and the papillary region (r = 0.512, p < 0.001, r = 0.292, p = 0.039). Patients receiving systemic antiviral therapy (SAT) showed better VAD of the peripapillary choriocapillary layer (p = 0.001, no therapy: 31.4 ± 1.9%, SAT: 35.0 ± 1.6%), and choroidal layer (p = 0.009, no therapy: 34.2 ± 0.3%, SAT: 36.3 ± 1.8%) compared to those with no SAT.

CONCLUSION

A lower peripapillary VAD in the SVC might indicate vascular dysfunction as a sign of glaucomatous damage. SAT might have positive effects on the microcirculation in the deep retinal and choroidal layers.

TRIAL REGISTRATION

TRN: DRKS00028266, https://www.drks.de/drks_web/ .

Extracellular Vesicles and Ischemic Cardiovascular Diseases

Characterized by coronary artery obstruction or stenosis, ischemic cardiovascular diseases as advanced stages of coronary heart diseases commonly lead to left ventricular aneurysm, ventricular septal defect, and mitral insufficiency. Extracellular vesicles (EVs) secreted by diverse cells in the body exert roles in cell-cell interactions and intrinsic cellular regulations. With a lipid double-layer membrane and biological components such as DNA, protein, mRNA, microRNAs (miRNA), and siRNA inside, the EVs function as paracrine signaling for the pathophysiology of ischemic cardiovascular diseases and maintenance of the cardiac homeostasis. Unlike stem cell transplantation with the potential tumorigenicity and immunogenicity, the EV-based therapeutic strategy is proposed to satisfy the demand for cardiac repair and regeneration while the circulating EVs detected by a noninvasive approach can act as precious biomarkers. In this chapter, we extensively summarize the cardioprotective functions of native EVs and bioengineered EVs released from stem cells, cardiomyocytes, cardiac progenitor cells (CPCs), endothelial cells, fibroblast, smooth muscle cells, and immune cells. In addition, the potential of EVs as robust molecule biomarkers is discussed for clinical diagnosis of ischemic cardiovascular disease, attributed to the same pathology of EVs as that of their origin. Finally, we highlight EV-based therapy as a biocompatible alternative to direct cell-based therapy for ischemic cardiovascular diseases.

ADAM9: A regulator between HCMV infection and function of smooth muscle cells

Lots of epidemiological and clinical studies have shown that human cytomegalovirus (HCMV) is related to the pathogenesis of atherosclerosis. Released by inflammatory cells and vascular smooth muscle cell (VSMCs), metalloproteinases are observed in many pathological vessel conditions, including atherosclerosis and restenosis. This study was designed to investigate the effect of HCMV infection on the expression of metalloproteinases and their involvements in the HCMV-induced functional changes of VSMCs. Differential metalloproteinase after HCMV infection was assayed using reverse transcription-polymerase chain reaction (RT-PCR) microarray. The most significant increased a disintegrin and metalloprotease 9 (ADAM9) was chosen to investigate the mechanism of its specific increase after infection using the treatment of UV-irradiated replication-deficient HCMV, HCMV-infected cell lysate filters or Foscarnet. The function of proliferation, migration, production of inflammatoty factors and phenotypic transformation were determined by using cell counting kit-8, transwell, Enzyme-linked immunosorbent assay, RT-quantitative PCR (qPCR) and Western blot, respectively. Moreover, the effect of ADAM9 deficiency on HCMV replication was also determined using RT-qPCR and immunofluorescence. The expression levels of 6 genes were upregulated and 14 genes were downregulated at different time points after HCMV infection. Among these, the expression level of ADAM9 increased most significantly at each time point and the abnormal expression of ADAM9 might be induced by the early gene products of HCMV. Further studies found that ADAM9 promoted the proliferation, the migration, the production of inflammatory factors and the transit from the contractile phenotype (decreased ACTA2 expression) to the synthetic phenotype (increased osteopontin [OPN] expression). Knockdown theADAM9 expression could rescue the decreased ACTA2 expression, but has no effect on OPN expression. ADAM-9 deficiency didn't affect the replication of HCMV. The findings of our study suggest that HCMV infection changed VSMC function through ADAM9 expression, which may contribute to the understanding of the underlying pathological mechanisms of HCMV-induced atherosclerosis.

γδ T Cell Subpopulations Associate with Recovery of Memory Function in Indonesian HIV Patients Starting Antiretroviral Therapy

Cognitive impairment may persist in HIV patients despite effective antiretroviral therapy (ART). However, recovery is influenced by the neurocognitive domain tested, the severity of HIV disease, and by education. In young adult patients commencing ART in Jakarta, Indonesia, we described improvements in all cognitive domains except memory after 6-12 months on ART. In this study, we address relationships between cytomegalovirus (CMV), γδ T cell profiles and neurocognitive assessments with a focus on memory. The JakCCANDO (Jakarta CMV Cardiovascular ART Neurology Dentistry Ophthalmology) project recruited patients (aged 18-48 years) beginning ART with <200 CD4⁺ T cells/μL. Cognitive assessments used validated tests of five domains. Flow cytometry was used to assess proportions of Vδ2^- and Vδ2⁺ γδ T cells, and their activation (HLA-DR) and terminal differentiation (CD27^-/CD45RA⁺). All patients carried high levels of antibodies reactive with CMV, so the detection of CMV DNA before ART was used to stratify participants into subgroups with a moderate/high or an extremely high burden of CMV. Patients had higher proportions of Vδ2^- γδ T cells and fewer Vδ2⁺ γδ T cells than healthy controls before ART and at 6 months. Z-scores for memory function correlated with proportions of Vδ2⁺ γδ T cells at both time points. Linear regression analyses confirmed this association. When the detection of CMV DNA was used to stratify the cohort, the association between memory Z-scores and Vδ2⁺ γδ T cells or CMV antibodies was only discernible in patients with a lower CMV burden. Hence, CMV and Vδ2⁺ γδ T cells warrant further consideration as factors that may contribute to the poor recovery of memory on ART.

Identification of host-pathogen-disease relationships using a scalable multiplex serology platform in UK Biobank

Certain infectious agents are recognised causes of cancer and other chronic diseases. To understand the pathological mechanisms underlying such relationships, here we design a Multiplex Serology platform to measure quantitative antibody responses against 45 antigens from 20 infectious agents including human herpes, hepatitis, polyoma, papilloma, and retroviruses, as well as Chlamydia trachomatis, Helicobacter pylori and Toxoplasma gondii, then assayed a random subset of 9695 UK Biobank participants. We find seroprevalence estimates consistent with those expected from prior literature and confirm multiple associations of antibody responses with sociodemographic characteristics (e.g., lifetime sexual partners with C. trachomatis), HLA genetic variants (rs6927022 with Epstein-Barr virus (EBV) EBNA1 antibodies) and disease outcomes (human papillomavirus-16 seropositivity with cervical intraepithelial neoplasia, and EBV responses with multiple sclerosis). Our accessible dataset is one of the largest incorporating diverse infectious agents in a prospective UK cohort offering opportunities to improve our understanding of host-pathogen-disease relationships with significant clinical and public health implications.

Infections as Novel Risk Factors of Atherosclerotic Cardiovascular Diseases: Pathophysiological Links and Therapeutic Implications

Atherosclerotic cardiovascular diseases (ASCVD) are the major cause of mortality worldwide. Despite the continuous progress in ASCVD therapy, the residual risk persists beyond the management of traditional risk factors. Several infections including Helicobacter pylori infection, periodontal disease, and viral infections are associated with the increased risk of ASCVD, both directly by damage to the heart muscle and vasculature, and indirectly by triggering a systemic proinflammatory state. Hence, beyond the optimal management of the traditional ASCVD risk factors, infections should be considered as an important non-classical risk factor to enable early diagnosis and appropriate treatment. Here, we summarized the currently available evidence regarding the role of inflammation in ASCVD and the association between the particular infections and pathogens (Helicobacter pylori, periodontal disease, pneumonia, Cytomegalovirus, Human immunodeficiency virus, Herpes simplex virus, and severe acute respiratory syndrome coronavirus 2) on the development and progression of ASCVD. We also speculated about the potential therapeutic implications of the anti-inflammatory and anti-infective drugs on ASCVD outcomes, including drugs routinely administered in patients with ASCVD (statins, P2Y12 receptor inhibitors, and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers) and novel strategies aiming at residual risk reduction (colchicine, anti-cytokine drugs, and methotrexate). Considering the emerging association between infections and ASCVD, it is crucial to determine the possible advantages of infection prevention and treatment in patients with ASCVD.

Cell type-specific biogenesis of novel vesicles containing viral products in human cytomegalovirus infection

Human cytomegalovirus (HCMV), while highly restricted for the human species, infects an diverse array of cell types in the host. Patterns of infection are dictated by the cell type infected, but cell type-specific factors and how they impact tropism for specific cell types is poorly understood. Previous studies in primary endothelial cells showed that HCMV infection induces large multivesicular-like bodies (MVBs) that incorporate viral products, including dense bodies (DBs) and virions. Here we define the nature of these large vesicles using a recombinant virus where UL32, encoding the pp150 tegument protein, is fused in frame with green fluorescent protein (GFP, TB40/E-UL32-GFP). In fibroblasts, UL32-GFP-positive vesicles were marked with classical markers of MVBs, including CD63 and lysobisphosphatidic acid (LBPA), both classical MVB markers, as well as the clathrin and LAMP1. Unexpectedly, UL32-GFP-positive vesicles in primary human microvascular endothelial cells (HMVECs) were not labeled by CD63, and LBPA was completely lost from infected cells. We defined these UL32-positive vesicles in endothelial cells using markers for the cis-Golgi (GM130), lysosome (LAMP1), and autophagy (LC3B). These findings suggest that UL32-GFP containing MVBs in fibroblasts are derived from the canonical endocytic pathway and takeover classical exosomal release pathway. However, UL32-GFP containing MVBs in HMVECs are derived from the early biosynthetic pathway and exploit a less characterized early Golgi-LAMP1-associated non- canonical secretory autophagy pathway. These results reveal striking cell-type specific membrane trafficking differences in host pathways that are exploited by HCMV, which may reflect distinct pathways for virus egress.ImportanceHuman cytomegalovirus (HCMV) is a herpesvirus that, like all herpesvirus, that establishes a life-long infection. HCMV remains a significant cause of morbidity and mortality in the immunocompromised and HCMV seropositivity is associated with age-related pathology. HCMV infects many cells in the human host and the biology underlying the different patterns of infection in different cell types is poorly understood. Endothelial cells are important target of infection that contribute to hematogenous spread of the virus to tissues. Here we define striking differences in the biogenesis of large vesicles that incorporate virions in fibroblasts and endothelial cells. In fibroblasts, HCMV is incorporated into canonical MVBs derived from an endocytic pathway, whereas HCMV matures through vesicles derived from the biosynthetic pathway in endothelial cells. This work defines basic biological differences between these cell types that may impact how progeny virus is trafficked out of infected cells.

Cytomegalovirus Disease, Short-Term Cardiovascular Events and Graft Survival in a Cohort of Kidney Transplant Recipients With High CMV IgG Seroprevalence

INTRODUCTION

Both cytomegalovirus (CMV) infection and CMV disease have been linked with several long-term indirect effects in kidney transplant recipients. Research questions: We conducted a retrospective study to assess the association between cytomegalovirus disease and risks of death, shortterm cardiovascular events and graft loss in a cohort of renal transplant recipients.

DESIGN

The associations between CMV disease and death and cardiovascular events were determined using Cox regression models, while the association between viral disease and graft loss risk was analyzed through a competing risks regression according to the Fine and Gray method. Death with a functioning graft was considered as a competing risk event.

RESULTS

A total of 865 consecutive renal transplant recipients were included. The prevalence of seropositive donor/seronegative recipient (D+/R-) group was 89.9% with the remaining patients classified as seropositive recipient (R+). After median follow-up time of 24.4 months, CMV disease was not a risk factor for all-causes mortality (HR = 1.75; 95% CI 0.94-3.25), early cardiovascular events (HR = 0.54; 95% CI 0.16-1.82) or graft loss (subhazard ratio [the HR adjusted for competing risk of death with functioning graft] = 0.99; 95% CI 0.53-1.84).

CONCLUSIONS

In this cohort with high prevalence of CMV IgG antibodies, we found no association between cytomegalovirus disease and risk of death or graft loss. The relationship between CMV and cardiovascular disease remains to be unraveled and probably corresponds to a multifactorial phenomenon involving individual risk factors and the immune response to infection rather than the virus effect itself.

Overview of Human Cytomegalovirus Pathogenesis

Human cytomegalovirus (HCMV) is a betaherpesvirus with a global seroprevalence of 60-90%. HCMV is the leading cause of congenital infections and poses a great health risk to immunocompromised individuals. Although HCMV infection is typically asymptomatic in the immunocompetent population, infection can result in mononucleosis and has also been associated with the development of certain cancers, as well as chronic inflammatory diseases such as various cardiovascular diseases. In immunocompromised patients, including AIDS patients, transplant recipients, and developing fetuses, HCMV infection is associated with increased rates of morbidity and mortality. Currently there is no vaccine for HCMV and there is a need for new pharmacological treatments. Ongoing research seeks to further define the complex aspects of HCMV pathogenesis, which could potentially lead to the generation of new therapeutics to mitigate the disease states associated with HCMV infection. The following chapter reviews the advancements in our understanding of HCMV pathogenesis in the immunocompetent and immunocompromised hosts.

Differential clusterization of soluble and extracellular vesicle-associated cytokines in myocardial infarction

A proinflammatory dysregulation of cytokine release is associated with various diseases, in particular with those of infectious etiology, as well as with cardiovascular diseases (CVD). We showed earlier that cytokines are released in two forms, soluble and in association with extracellular vesicles (EVs). Here, we investigated the patterns of expression and clustering of soluble and EV-associated cytokines in patients with ST-elevation myocardial infarction (STEMI). We collected plasma samples from 48 volunteers without CVD and 62 patients with STEMI, separated soluble and EV fractions, and analyzed them for 33 cytokines using a multiplexed bead-based assay. We identified soluble and EV-associated cytokines that are upregulated in STEMI and form correlative clusters. Several clustered soluble cytokines were expressed almost exclusively in patients with STEMI. EV-associated cytokines were largely not affected by STEMI, except for pro-inflammatory cytokines IL-6, IL-18, and MIG, as well as anti-inflammatory IL-2 that were upregulated in a correlated fashion. Our results demonstrated that soluble cytokines in patients with STEMI are upregulated in a coordinated fashion in contrast to the mainly unaffected system of EV-associated cytokines. Identification of cytokine clusters affected differently by STEMI now permits investigation of their differential contributions to this pathology.

Limited effect of duration of CMV infection on adaptive immunity and frailty: insights from a 27-year-long longitudinal study

Objectives

Cytomegalovirus infection is thought to affect the immune system and to impact general health during ageing. Higher CMV‐specific antibody levels in the elderly are generally assumed to reflect experienced viral reactivation during life. Furthermore, high levels of terminally differentiated and CMV‐specific T cells are hallmarks of CMV infection, which are thought to expand over time, a process also referred to as memory inflation.

Methods

We studied CMV‐specific antibody levels over ~ 27 years in 268 individuals (aged 60–89 years at study endpoint), and to link duration of CMV infection to T‐cell numbers, CMV‐specific T‐cell functions, frailty and cardiovascular disease at study endpoint.

Results

In our study, 136/268 individuals were long‐term CMV seropositive and 19 seroconverted during follow‐up (seroconversion rate: 0.56%/year). CMV‐specific antibody levels increased slightly over time. However, we did not find an association between duration of CMV infection and CMV‐specific antibody levels at study endpoint. No clear association between duration of CMV infection and the size and function of the memory T‐cell pool was observed. Elevated CMV‐specific antibody levels were associated with the prevalence of cardiovascular disease but not with frailty. Age at CMV seroconversion was positively associated with CMV‐specific antibody levels, memory CD4⁺ T‐cell numbers and frailty.

Conclusion

Cytomegalovirus‐specific memory T cells develop shortly after CMV seroconversion but do not seem to further increase over time. Age‐related effects other than duration of CMV infection seem to contribute to CMV‐induced changes in the immune system. Although CMV‐specific immunity is not evidently linked to frailty, it tends to associate with higher prevalence of cardiovascular disease.

New Insights Into the Molecular Mechanisms and Immune Control of Cytomegalovirus Reactivation

Cytomegalovirus (CMV) is a β-herpesvirus that establishes lifelong latency in infected hosts. Following transplantation of a latently infected organ, reactivation can occur and consists of a spectrum of clinically apparent syndromes from mild symptoms to tissue-invasive, resulting in both direct and indirect sequelae. Before the advent of effective antiviral agents, the primary treatment was reduction in immunosuppression (IS). While antiviral agents provide effective prophylaxis, there are several important caveats associated with their use, including drug toxicity and resistance. The traditional view attributes CMV reactivation and the ensuing clinical disease primarily to IS, either intrinsic to disease-related immune compromise or from the extrinsic administration of IS agents. However, previous data from both animal models and human subjects showed that inflammatory signals could induce upregulation of latent viral gene expression. New data demonstrate that ischemia/reperfusion is necessary and sufficient to induce CMV reactivation following murine transplantation of a latently infected graft. In this article, we review a growing body of evidence that suggests that reactivation of both human CMV and murine CMV is first triggered by molecular events that activate CMV gene expression and lytic infection and viral dissemination are then facilitated by IS. The initial activation of viral gene expression may be mediated by oxidative stress, DNA damage, or inflammatory cytokines, and these factors may act synergistically. New therapeutic approaches are needed to capture this complex array of targets.

Novel Strategies to Combat CMV-Related Cardiovascular Disease

Cytomegalovirus (CMV), a ubiquitous human pathogen that is never cleared from the host, has long been thought to be relatively innocuous in immunocompetent adults, but causes severe complications including blindness, end-organ disease, and death in newborns and in immuno-compromised individuals, such as organ transplant recipients and those suffering from AIDS. Yet even in persons with intact immunity, CMV infection is associated with profound stimulation of immune and inflammatory pathways. Carriers of CMV infection also have an elevated risk of developing cardiovascular complications. In this review, we define the proposed mechanisms of how CMV contributes to cardiovascular disease (CVD), describe current approaches to target CMV, and discuss how these strategies may or may not alleviate cardiovascular complications in those with CMV infection. In addition, we discuss the special situation of CMV coinfection in people with HIV infection receiving antiretroviral therapy, and describe how these 2 viral infections may interact to potentiate CVD in this especially vulnerable population.

Cytomegalovirus Latency and Reactivation: An Intricate Interplay With the Host Immune Response

CMV is an ancient herpesvirus that has co-evolved with its host over millions of years. The 236 kbp genome encodes at least 165 genes, four non-coding RNAs and 14 miRNAs. Of the protein-coding genes, 43-44 are core replication genes common to all herpesviruses, while ~30 are unique to betaherpesviruses. Many CMV genes are involved in evading detection by the host immune response, and others have roles in cell tropism. CMV replicates systemically, and thus, has adapted to various biological niches within the host. Different biological niches may place competing demands on the virus, such that genes that are favorable in some contexts are unfavorable in others. The outcome of infection is dependent on the cell type. In fibroblasts, the virus replicates lytically to produce infectious virus. In other cell types, such as myeloid progenitor cells, there is an initial burst of lytic gene expression, which is subsequently silenced through epigenetic repression, leading to establishment of latency. Latently infected monocytes disseminate the virus to various organs. Latency is established through cell type specific mechanisms of transcriptional silencing. In contrast, reactivation is triggered through pathways activated by inflammation, infection, and injury that are common to many cell types, as well as differentiation of myeloid cells to dendritic cells. Thus, CMV has evolved a complex relationship with the host immune response, in which it exploits cell type specific mechanisms of gene regulation to establish latency and to disseminate infection systemically, and also uses the inflammatory response to infection as an early warning system which allows the virus to escape from situations in which its survival is threatened, either by cellular damage or infection of the host with another pathogen. Spontaneous reactivation induced by cellular aging/damage may explain why extensive expression of lytic genes has been observed in recent studies using highly sensitive transcriptome analyses of cells from latently infected individuals. Recent studies with animal models highlight the potential for harnessing the host immune response to blunt cellular injury induced by organ transplantation, and thus, prevent reactivation of CMV and its sequelae.

Emerging Role of Compartmentalized G Protein-Coupled Receptor Signaling in the Cardiovascular Field

G protein-coupled receptors (GPCRs) are cell surface receptors that for many years have been considered to function exclusively at the plasma membrane, where they bind to extracellular ligands and activate G protein signaling cascades. According to the conventional model, these signaling events are rapidly terminated by β-arrestin (β-arr) recruitment to the activated GPCR resulting in signal desensitization and receptor internalization. However, during the past decade, emerging evidence suggest that many GPCRs can continue to activate G proteins from intracellular compartments after they have been internalized. G protein signaling from intracellular compartments is in general more sustained compared to G protein signaling at the plasma membrane. Notably, the particular location closer to the nucleus is beneficial for selective cellular functions such as regulation of gene transcription. Here, we review key GPCRs that undergo compartmentalized G protein signaling and discuss molecular considerations and requirements for this signaling to occur. Our main focus will be on receptors involved in the regulation of important physiological and pathological cardiovascular functions. We also discuss how sustained G protein activation from intracellular compartments may be involved in cellular functions that are distinct from functions regulated by plasma membrane G protein signaling, and the corresponding significance in cardiovascular physiology.

From Vaccine Vector to Oncomodulation: Understanding the Complex Interplay between CMV and Cancer

Cytomegalovirus (CMV) is a herpesvirus that establishes a persistent, but generally asymptomatic, infection in most people in the world. However, CMV drives and sustains extremely large numbers of antigen-specific T cells and is, therefore, emerging as an exciting platform for vaccines against infectious diseases and cancer. Indeed, pre-clinical data strongly suggest that CMV-based vaccines can sustain protective CD8+ T cell and antibody responses. In the context of vaccines for infectious diseases, substantial pre-clinical studies have elucidated the efficacy and protective mechanisms of CMV-based vaccines, including in non-human primate models of various infections. In the context of cancer vaccines, however, much less is known and only very early studies in mice have been conducted. To develop CMV-based cancer vaccines further, it will be critical to better understand the complex interaction of CMV and cancer. An array of evidence suggests that naturally-acquired human (H)CMV can be detected in cancers, and it has been proposed that HCMV may promote tumor growth. This would obviously be a concern for any therapeutic cancer vaccines. In experimental models, CMV has been shown to play both positive and negative roles in tumor progression, depending on the model studied. However, the mechanisms are still largely unknown. Thus, more studies assessing the interaction of CMV with the tumor microenvironment are needed. This review will summarize the existing literature and major open questions about CMV-based vaccines for cancer, and discuss our hypothesis that the balance between pro-tumor and anti-tumor effects driven by CMV depends on the location and the activity of the virus in the lesion.