Human cytomegalovirus harbors its own unique IL-10 homolog (cmvIL-10)

An IL-10 homologue encoded by human cytomegalovirus is linked with the viral "footprint" in clinical samples

Persistent infections with human cytomegalovirus (HCMV) affect the hosts' immune system and have been linked with chronic inflammation and cardiovascular disease. These effects may be influenced by a HCMV-encoded homologue of the anti-inflammatory cytokine, IL-10 (cmvIL-10). To assess this, we quantitated cmvIL-10 in plasma from renal transplant recipients (RTR) and healthy adults. Detectable levels of cmvIL-10 associated with seropositivity in RTR, but were found in some seronegative healthy adults. RTR with detectable cmvIL-10 had elevated interferon-γ T-cell responses to HCMV antigens, whilst cmvIL-10 in healthy adults associated with reduced populations of terminally-differentiated T-cells - a known "footprint" of HCMV. Plasma cmvIL-10 associated with lower VCAM-1 levels in healthy adults. The data suggest cmvIL-10 may suppress seroconversion and/or reduce the footprint of HCMV in healthy adults. This appears to be subverted in RTR by their high burden of HCMV and/or immune dysregulation associated with transplantation. A role for cmvIL-10 in protection of vascular health is discussed.

Systems analysis of innate and adaptive immunity in Long COVID

Since the onset of the COVID-19 pandemic, significant progress has been made in developing effective preventive and therapeutic strategies against severe acute SARS-CoV-2 infection. However, the management of Long COVID (LC), an infection-associated chronic condition that has been estimated to affect 5-20% of individuals following SARS-CoV-2 infection, remains challenging due to our limited understanding of its mechanisms. Although LC is a heterogeneous disease that is likely to have several subtypes, immune system disturbances appear common across many cases. The extent to which these immune perturbations contribute to LC symptoms, however, is not entirely clear. Recent advancements in multi-omics technologies, capable of detailed, cell-level analysis, have provided valuable insights into the immune perturbations associated with LC. Although these studies are largely descriptive in nature, they are the crucial first step towards a deeper understanding of the condition and the immune system's role in its development, progression, and resolution. In this review, we summarize the current understanding of immune perturbations in LC, covering both innate and adaptive immune responses, and the cytokines and analytes involved. We explore whether these findings support or challenge the primary hypotheses about LC's underlying mechanisms. We also discuss the crosstalk between various immune system components and how it can be disrupted in LC. Finally, we emphasize the need for more tissue- and subtype-focused analyses of LC, and for enhanced collaborative efforts to analyze common specimens from large cohorts, including those undergoing therapeutic interventions. These collective efforts are vital to unravel the fundaments of this new disease, and could also shed light on the prevention and treatment of the larger family of chronic illnesses linked to other microbial infections.

Pro-Inflammatory and Anti-Inflammatory Interleukins in Infectious Diseases: A Comprehensive Review

Interleukins (ILs) are signaling molecules that are crucial in regulating immune responses during infectious diseases. Pro-inflammatory ILs contribute to the activation and recruitment of immune cells, whereas anti-inflammatory ILs help to suppress excessive inflammation and promote tissue repair. Here, we provide a comprehensive overview of the role of pro-inflammatory and anti-inflammatory ILs in infectious diseases, with a focus on the mechanisms underlying their effects, their diagnostic and therapeutic potential, and emerging trends in IL-based therapies.

HCMV-secreted glycoprotein gpUL4 inhibits TRAIL-mediated apoptosis and NK cell activation

Human cytomegalovirus (HCMV) is a paradigm of pathogen immune evasion and sustains lifelong persistent infection in the face of exceptionally powerful host immune responses through the concerted action of multiple immune-evasins. These reduce NK cell activation by inhibiting ligands for activating receptors, expressing ligands for inhibitory receptors, or inhibiting synapse formation. However, these functions only inhibit direct interactions with the infected cell. To determine whether the virus also expresses soluble factors that could modulate NK function at a distance, we systematically screened all 170 HCMV canonical protein-coding genes. This revealed that UL4 encodes a secreted and heavily glycosylated protein (gpUL4) that is expressed with late-phase kinetics and is capable of inhibiting NK cell degranulation. Analyses of gpUL4 binding partners by mass spectrometry identified an interaction with TRAIL. gpUL4 bound TRAIL with picomolar affinity and prevented TRAIL from binding its receptor, thus acting as a TRAIL decoy receptor. TRAIL is found in both soluble and membrane-bound forms, with expression of the membrane-bound form strongly up-regulated on NK cells in response to interferon. gpUL4 inhibited apoptosis induced by soluble TRAIL, while also binding to the NK cell surface in a TRAIL-dependent manner, where it blocked NK cell degranulation and cytokine secretion. gpUL4 therefore acts as an immune-evasin by inhibiting both soluble and membrane-bound TRAIL and is a viral-encoded TRAIL decoy receptor. Interestingly, gpUL4 could also suppress NK responses to heterologous viruses, suggesting that it may act as a systemic virally encoded immunosuppressive agent.

An important call: Suggestion of using IL-10 as therapeutic agent for COVID-19 with ARDS and other complications

The global coronavirus disease 2019 (COVID-19) pandemic has a detrimental impact on public health. COVID-19 usually manifests as pneumonia, which can progress into acute respiratory distress syndrome (ARDS) related to uncontrolled TH17 immune reaction. Currently, there is no effective therapeutic agent to manage COVID-19 with complications. The currently available anti-viral drug remdesivir has an effectiveness of 30% in SARS-CoV-2-induced severe complications. Thus, there is a need to identify effective agents to treat COVID-19 and the associated acute lung injury and other complications. The host immunological pathway against this virus typically involves the THαβ immune response. THαβ immunity is triggered by type 1 interferon and interleukin-27 (IL-27), and the main effector cells of the THαβ immune response are IL10-CD4 T cells, CD8 T cells, NK cells, and IgG1-producing B cells. In particular, IL-10 exerts a potent immunomodulatory or anti-inflammatory effect and is an anti-fibrotic agent for pulmonary fibrosis. Concurrently, IL-10 can ameliorate acute lung injury or ARDS, especially those caused by viruses. Owing to its anti-viral activity and anti-pro-inflammatory effects, in this review, IL-10 is suggested as a possible treatment agent for COVID-19.

The Human Cytomegalovirus Latency-Associated Gene Product Latency Unique Natural Antigen Regulates Latent Gene Expression

Human cytomegalovirus (HCMV) infection can lead to either lytic or latent infection, which is dependent on the regulation of the viral major immediate early promoter (MIEP). Suppression of the MIEP is a pre-requisite for latency and is driven by repressive epigenetic modifications at the MIEP during latent infection. However, other viral genes are expressed during latency and this is correlated with activatory epigenetic modifications at latent gene promoters. Yet the molecular basis of the differential regulation of latent and lytic gene expression by epigenetics is unclear. LUNA, a latent viral transcript, has been suggested to be important for HCMV latency and has also been shown to be important for efficient reactivation likely through its known deSUMOylase activity. Intriguingly, we and others have also observed that LUNA enhances latency-associated expression of the viral UL138 gene. Here, we show that in the absence of LUNA, the expression of multiple latency-associated transcripts is reduced during latent infection, which is correlated with a lack of activatory marks at their promoters. Interestingly, we also show that LUNA interacts with the hematopoietic transcription factor GATA-2, which has previously been shown to bind to a number of latency-associated gene promoters, and that this interaction is dependent on the deSUMOylase domain of LUNA. Finally, we show that the deSUMOylase activity of LUNA is required for the establishment and/or maintenance of an open chromatin configuration around latency-associated gene promoters. As such, LUNA plays a key role in efficient latency-associated viral gene expression and carriage of viral genome during latent carriage.

Insights into the Transcriptome of Human Cytomegalovirus: A Comprehensive Review

Human cytomegalovirus (HCMV) is a widespread pathogen that poses significant risks to immunocompromised individuals. Its genome spans over 230 kbp and potentially encodes over 200 open-reading frames. The HCMV transcriptome consists of various types of RNAs, including messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), with emerging insights into their biological functions. HCMV mRNAs are involved in crucial viral processes, such as viral replication, transcription, and translation regulation, as well as immune modulation and other effects on host cells. Additionally, four lncRNAs (RNA1.2, RNA2.7, RNA4.9, and RNA5.0) have been identified in HCMV, which play important roles in lytic replication like bypassing acute antiviral responses, promoting cell movement and viral spread, and maintaining HCMV latency. CircRNAs have gained attention for their important and diverse biological functions, including association with different diseases, acting as microRNA sponges, regulating parental gene expression, and serving as translation templates. Remarkably, HCMV encodes miRNAs which play critical roles in silencing human genes and other functions. This review gives an overview of human cytomegalovirus and current research on the HCMV transcriptome during lytic and latent infection.

Polyploid giant cancer cells, cytokines and cytomegalovirus in breast cancer progression

BACKGROUND

Breast cancer is the most common cancer among women. Accumulated evidence over the past decades indicates a very high prevalence of human cytomegalovirus (HCMV) in breast cancer. High-risk HCMV strains possess a direct oncogenic effect displayed by cellular stress, polyploid giant cancer cells (PGCCs) generation, stemness, and epithelial-to-mesenchymal transition (EMT) leading to cancer of aggressive phenotype. Breast cancer development and progression have been regulated by several cytokines where the latter can promote cancer cell survival, help in tumor immune evasion, and initiate the EMT process, thereby resulting in invasion, angiogenesis, and breast cancer metastasis. In the present study, we screened cytokines expression in cytomegalovirus-transformed HMECs (CTH cells) cultures infected with HCMV high-risk strains namely, HCMV-DB and BL, as well as breast cancer biopsies, and analyzed the association between cytokines production, PGCCs count, and HCMV presence in vitro and in vivo.

METHODS

In CTH cultures and breast cancer biopsies, HCMV load was quantified by real-time qPCR. PGCCs count in CTH cultures and breast cancer biopsies was identified based on cell morphology and hematoxylin and eosin staining, respectively. CTH supernatants were evaluated for the production of TGF-β, IL-6, IL1-β, and IL-10 by ELISA assays. The above-mentioned cytokines expression was assessed in breast cancer biopsies using reverse transcription-qPCR. The correlation analyses were performed using Pearson correlation test.

RESULTS

The revealed PGCCs/cytokine profile in our in vitro CTH model matched that of the breast cancer biopsies, in vivo. Pronounced cytokine expression and PGCCs count were detected in particularly CTH-DB cultures and basal-like breast cancer biopsies.

CONCLUSIONS

The analysis of cytokine profiles in PGCCs present mostly in basal-like breast cancer biopsies and derived from CTH cells chronically infected with the high-risk HCMV strains might have the potential to provide novel therapies such as cytokine-based immunotherapy which is a promising field in cancer treatments.

Natural killer cells- from innate cells to the discovery of adaptability

Natural Killer (NK) cells have come a long way since their first description in the 1970's. The most recent reports of their adaptive-like behavior changed the way the immune system dichotomy is described. Adaptive NK cells present characteristics of both the innate and adaptive immune system. This NK cell subpopulation undergoes a clonal-like expansion in response to an antigen and secondary encounters with the same antigen result in an increased cytotoxic response. These characteristics can be of extreme importance in the clinical setting, especially as adoptive immunotherapies, since NK cells present several advantages compared other cell types. This review will focus on the discovery and the path to the current knowledge of the adaptive NK cell population.

Molecular and cellular factors determining the functional pleiotropy of cytokines

Cytokines are soluble factors vital for mammalian physiology. Cytokines elicit highly pleiotropic activities, characterized by their ability to induce a wide spectrum of functional responses in a diverse range of cell subsets, which makes their study very challenging. Cytokines activate signalling via receptor dimerization/oligomerization, triggering activation of the JAK (Janus kinase)/STAT (signal transducer and activator of transcription) signalling pathway. Given the strong crosstalk and shared usage of key components of cytokine signalling pathways, a long-standing question in the field pertains to how functional diversity is achieved by cytokines. Here, we discuss how biophysical - for example, ligand-receptor binding affinity and topology - and cellular - for example, receptor, JAK and STAT protein levels, endosomal compartment - parameters contribute to the modulation and diversification of cytokine responses. We review how these parameters ultimately converge into a common mechanism to fine-tune cytokine signalling that involves the control of the number of Tyr residues phosphorylated in the receptor intracellular domain upon cytokine stimulation. This results in different kinetics of STAT activation, and induction of specific gene expression programs, ensuring the generation of functional diversity by cytokines using a limited set of signalling intermediaries. We describe how these first principles of cytokine signalling have been exploited using protein engineering to design cytokine variants with more specific and less toxic responses for immunotherapy.

Neutrophil Extracellular Traps and Their Possible Implications in Ocular Herpes Infection

Neutrophil extracellular traps (NETs) are net-like structures released from neutrophils. NETs predominantly contain cell-free deoxyribonucleic acid (DNA) decorated with histones and neutrophil granule proteins. Numerous extrinsic and intrinsic stimuli can induce the formation of NETs such as pathogens, cytokines, immune complexes, microcrystals, antibodies, and other physiological stimuli. The mechanism of NETosis induction can either be ROS-dependent or independent based on the catalase producing activity of the pathogen. NADPH is the source of ROS production, which in turn depends on the upregulation of Ca2+ production in the cytoplasm. ROS-independent induction of NETosis is regulated through toll-like receptors (TLRs). Besides capturing and eliminating pathogens, NETs also aggravate the inflammatory response and thus act as a double-edged sword. Currently, there are growing reports of NETosis induction during bacterial and fungal ocular infections leading to different pathologies, but there is no direct report suggesting its role during herpes simplex virus (HSV) infection. There are innumerable independent reports showing that the major effectors of NETosis are also directly affected by HSV infection, and thus, there is a strong possibility that HSV interacts with these facilitators that can either result in virally mediated modulation of NETosis or NETosis-mediated suppression of ocular HSV infection. This review focuses on the mechanism of NETs formation during different ocular pathologies, with its prime focus on highlighting their potential implications during HSV ocular infections and acting as prospective targets for the treatment of ocular diseases.

Molecular modelling of the HCMV IL-10 protein isoforms and analysis of their interaction with the human IL-10 receptor

The human cytomegalovirus (HCMV) UL111A gene encodes several homologs of the cellular interleukin 10 (cIL-10). Alternative splicing in the UL111A region produces two relatively well-characterized transcripts designated cmvIL-10 (isoform A) and LAcmvIL-10 (isoform B). The cmvIL-10 protein is the best characterized, both structurally and functionally, and has many immunosuppressive activities similar to cIL-10, while LAcmvIL-10 has more restricted biological activities. Alternative splicing also results in five less studied UL111A transcripts encoding additional proteins homologous to cIL-10 (isoforms C to G). These transcripts were identified during productive HCMV infection of MRC-5 cells with the high passage laboratory adapted AD169 strain, and the structure and properties of the corresponding proteins are largely unknown. Moreover, it is unclear whether these protein isoforms are able to bind the cellular IL-10 receptor and induce signalling. In the present study, we investigated the expression spectrum of UL111A transcripts in fully permissive MRC-5 cells and semi permissive U251 cells infected with the low passage HCMV strain TB40E. We identified a new spliced transcript (H) expressed during productive infection. Using computational methods, we carried out molecular modelling studies on the three-dimensional structures of the HCMV IL-10 proteins encoded by the transcripts detected in our work (cmvIL-10 (A), LAcmvIL-10 (B), E, F and H) and on their interaction with the human IL-10 receptor (IL-10R1). The modelling predicts clear differences between the isoform structures. Furthermore, the in silico simulations (molecular dynamics simulation and normal-mode analyses) allowed us to evaluate regions that contain potential receptor binding sites in each isoform. The analyses demonstrate that the complexes between the isoforms and IL-10R1 present different types of molecular interactions and consequently different affinities and stabilities. The knowledge about structure and expression of specific viral IL-10 isoforms has implications for understanding of their properties and role in HCMV immune evasion and pathogenesis.

A filarial parasite-encoded human IL-10 receptor antagonist reveals a novel strategy to modulate host responses

Interleukin (IL)-10 is the primary cytokine driving the modulation of the host response in filarial infections. We performed binding assays with Brugia malayi antigen extracts and human IL-10R1. Bm5539 was the top-binding hit. We identified a short sequence, termed truncated Bm5339, that has structural similarities to the human IL-10 functional dimer. Sequence comparisons revealed that other filarial parasites possess Bm5539 orthologues. Using recombinant Bm5539 in a modified Luciferase Immunoprecipitation System assay, we confirmed that both the truncated and full-length forms of the protein can bind to human IL-10R1. Truncated Bm5539 could inhibit human IL-10-driven phosphorylation of STAT3, thereby demonstrating that Bm5539 acts as an IL-10 antagonist, most likely through competitive binding to the receptor. We provide a structural basis for these observations using computational modeling and simulations. This parasite-encoded cytokine receptor antagonist provides an additional lens through which parasite-induced modulation of the host immune response can be examined.

Cytomegalovirus viral interleukin-10 (cmvIL-10) in patients with Aspergillus infection and effects on clinical outcome

BACKGROUND

Human cytomegalovirus (CMV) is associated with aspergillosis, but the simultaneous presence of cytomegalovirus viral interleukin-10 (cmvIL-10) and aspergillosis has never been investigated. CmvIL-10 is produced by CMV-infected cells and acts as an immune modulator during CMV infection. The aim of this study was to evaluate cmvIL-10 levels in peripheral blood and its influence on the clinical outcomes of Aspergillus infection.

METHODS

Patients who visited or were admitted to the hospital with suspected Aspergillus infection, including invasive aspergillosis (IA) and chronic pulmonary aspergillosis (CPA), were prospectively enrolled. The cmvIL-10, human IL-10 (hIL-10), IL-1B, IL-6, IL-8, IFN-γ, and TNF-α levels in peripheral blood were measured.

RESULTS

Patients with Aspergillus infection had a higher level of cmvIL-10 than the control group (158±305 vs. 27.9±30.4 pg/mL, p<0.05). The level of cmvIL-10 was not correlated with CMV viremia or end-organ disease. The cmvIL-10 but not hIL-10 level was positively correlated with the IFN-γ level (p<0.05) and marginally negatively correlated with IL-1B and IL-8 levels (p<0.1). In patients with CPA, a high level of cmvIL-10 (≥100 pg/mL) was a poor prognostic factor for long-term survival (p<0.05). In contrast, CMV viremia or end-organ disease was associated with poor survival in patients with IA (p=0.05).

CONCLUSIONS

Aspergillus infection was associated with CMV coinfection with cmvIL-10 in blood. A cmvIL-10 concentration ≥100 pg/mL was a predictor for unfavourable outcome in CPA patients.

Effect of Cytomegalovirus Infection on the Central Nervous System: Implications for Psychiatric Disorders

Cytomegalovirus (CMV) is a common herpesvirus that establishes lifelong latent infections and interacts extensively with the host immune system, potentially contributing to immune activation and inflammation. Given its proclivity for infecting the brain and its reactivation by inflammatory stimuli, CMV is well known for causing central nervous system complications in the immune-naïve (e.g., in utero) and in the immunocompromised (e.g., in neonates, individuals receiving transplants or cancer chemotherapy, or people living with HIV). However, its potentially pathogenic role in diseases that are characterized by more subtle immune dysregulation and inflammation such as psychiatric disorders is still a matter of debate. In this chapter, we briefly summarize the pathogenic role of CMV in immune-naïve and immunocompromised populations and then review the evidence (i.e., epidemiological studies, serological studies, postmortem studies, and recent neuroimaging studies) for a link between CMV infection and psychiatric disorders with a focus on mood disorders and schizophrenia. Finally, we discuss the potential mechanisms through which CMV may cause CNS dysfunction in the context of mental disorders and conclude with a summary of the current state of play as well as potential future research directions in this area.

Parapoxvirus Interleukin-10 Homologues Vary in Their Receptor Binding, Anti-Inflammatory, and Stimulatory Activities

Homologues of interleukin (IL)-10, a pleiotropic immunomodulatory cytokine, have been identified in the Parapoxvirus genus. The first identified, Orf virus (ORFV) IL-10, greatly enhanced infection of its host, exhibiting immune modulatory effects equivalent to human IL-10. IL-10-like genes were then identified in Bovine papular stomatitis virus (BPSV), Pseudocowpox virus (PCPV), Red deerpox virus (RDPV) and Grey sealpox virus (GSPV). This study aimed to produce and characterise recombinant parapoxvirus IL-10s, then quantitatively compare their receptor binding and immunomodulatory activities. Recombinant IL-10s were expressed, purified, then characterised using bioinformatic, biochemical and enzymatic analyses. Anti-inflammatory effects were assessed in lipoteichoic acid-activated THP-1 monocytes, and stimulatory effects in MC/9 mast cells. IL-10 receptor (IL-10R)1 binding was detected in a competitive displacement assay. BPSV IL-10 inhibited production of monocyte chemoattractant protein (MCP)-1, IL-8 and IL-1β, induced mast cell proliferation, and bound IL-10R1 similarly to ORFV IL-10. PCPV IL-10 showed reduced MCP-1 inhibition, mast cell proliferation, and IL-10R1 binding. RDPV IL-10 displayed reduced inhibition of IL-8 and MCP-1 production. GSPV IL-10 showed limited inhibition of IL-1β production and stimulation of mast cell proliferation. These findings provide valuable insight into IL-10 receptor interactions, and suggest that the parapoxvirus IL-10s play similar pathogenic roles during infection of their hosts.

Sequencing of the Viral UL111a Gene Directly from Clinical Specimens Reveals Variants of HCMV-Encoded IL-10 That Are Associated with Altered Immune Responses to HCMV

Human cytomegalovirus (HCMV) is a beta-herpesvirus carried by ~80% of adults worldwide. Acute infections are often asymptomatic in healthy individuals but generate diverse syndromes in neonates, renal transplant recipients (RTR), and people with HIV (PWH). The HCMV gene UL111a encodes a homolog of human interleukin-10 (IL-10) that interacts with the human IL-10 receptor. Deep sequencing technologies were used to sequence UL111a directly from 59 clinical samples from Indonesian PWH and Australian RTR, healthy adults, and neonates. Overall, 93% of samples contained more than one variant of HCMV, as defined by at least one nonsynonymous variation. Carriage of these variants differed between neonates and adults, Australians and Indonesians, and between saliva and blood leukocytes. The variant alleles of N41D and S71Y occurred together in Australian RTR and were associated with higher T-cell responses to HCMV pp65. The variant P122S was associated with lower levels of antibodies reactive with a lysate of HCMV-infected fibroblasts. L174F was associated with increased levels of antibodies reactive with HCMV lysate, immediate-early 1 (IE-1), and glycoprotein B (gB) in Australian RTR and Indonesians PWH, suggesting a higher viral burden. We conclude that variants of UL111a are common in all populations and may influence systemic responses to HCMV.

The complex biology of human cytomegalovirus latency

While many viral infections are limited and eventually resolved by the host immune response or by death of the host, other viruses establish long-term relationships with the host by way of a persistent infection, that range from chronic viruses that may be eventually cleared to those that establish life-long persistent or latent infection. Viruses infecting hosts from bacteria to humans establish quiescent infections that must be reactivated to produce progeny. For mammalian viruses, most notably herpesviruses, this quiescent maintenance of viral genomes in the absence of virus replication is referred to as latency. The latent strategy allows the virus to persist quiescently within a single host until conditions indicate a need to reactivate to reach a new host or, to re-seed a reservoir within the host. Here, I review common themes in viral strategies to regulate the latent cycle and reactivate from it ranging from bacteriophage to herpesviruses with a focus on human cytomegalovirus (HCMV). Themes central to herpesvirus latency include, epigenetic repression of viral gene expression and mechanisms to regulate host signaling and survival. Critical to the success of a latent program are mechanisms by which the virus can "sense" fluctuations in host biology (within the host) or environment (outside the host) and make appropriate "decisions" to maintain latency or re-initiate the replicative program. The signals or environments that indicate the establishment of a latent state, the very nature of the latent state, as well as the signals driving reactivation have been topics of intense study from bacteriophage to human viruses, as these questions encompass the height of complexity in virus-host interactions-where the host and the virus coexist.

Virus-host protein interactions as footprints of human cytomegalovirus replication

Human cytomegalovirus (HCMV) is a pervasive β-herpesvirus that causes lifelong infection. The lytic replication cycle of HCMV is characterized by global organelle remodeling and dynamic virus-host interactions, both of which are necessary for productive HCMV replication. With the advent of new technologies for investigating protein-protein and protein-nucleic acid interactions, numerous critical interfaces between HCMV and host cells have been identified. Here, we review temporal and spatial virus-host interactions that support different stages of the HCMV replication cycle. Understanding how HCMV interacts with host cells during entry, replication, and assembly, as well as how it interfaces with host cell metabolism and immune responses promises to illuminate processes that underlie the biology of infection and the resulting pathologies.

The Activated Macrophage - A Tough Fortress for Virus Invasion: How Viruses Strike Back

Macrophages (Mφ) are innate immune cells with a variety of functional phenotypes depending on the cytokine microenvironment they reside in. Mφ exhibit distinct activation patterns that are found within a wide array of activation states ranging from the originally discovered classical pro-inflammatory (M1) to the anti-inflammatory (M2) with their multi-facades. M1 cells are induced by IFNγ + LPS, while M2 are further subdivided into M2a (IL-4), M2b (Immune Complex) and M2c (IL-10) based on their inducing stimuli. Not surprisingly, Mφ activation influences the outcome of viral infections as they produce cytokines that in turn activate cells of the adaptive immune system. Generally, activated M1 cells tend to restrict viral replication, however, influenza and HIV exploit inflammation to support their replication. Moreover, M2a polarization inhibits HIV replication at the post-integration level, while HCMV encoded hrIL-10 suppresses inflammatory reactions by facilitating M2c formation. Additionally, viruses such as LCMV and Lassa Virus directly suppress Mφ activation leading to viral chronicity. Here we review how Mφ activation affects viral infection and the strategies by which viruses manipulate Mφ polarization to benefit their own fitness. An understanding of these mechanisms is important for the development of novel immunotherapies that can sway Mφ phenotype to inhibit viral replication.

Understanding the interaction between cytomegalovirus and tuberculosis in children: The way forward

Over 1 million children develop tuberculosis (TB) each year, with a quarter dying. Multiple factors impact the risk of a child being exposed to Mycobacterium tuberculosis (Mtb), the risk of progressing to TB disease, and the risk of dying. However, an emerging body of evidence suggests that coinfection with cytomegalovirus (CMV), a ubiquitous herpes virus, impacts the host response to Mtb, potentially influencing the probability of disease progression, type of TB disease, performance of TB diagnostics, and disease outcome. It is also likely that infection with Mtb impacts CMV pathogenesis. Our current understanding of the burden of these 2 diseases in children, their immunological interactions, and the clinical consequence of coinfection is incomplete. It is also unclear how potential interventions might affect disease progression and outcome for TB or CMV. This article reviews the epidemiological, clinical, and immunological literature on CMV and TB in children and explores how the 2 pathogens interact, while also considering the impact of HIV on this relationship. It outlines areas of research uncertainty and makes practical suggestions as to potential studies that might address these gaps. Current research is hampered by inconsistent definitions, study designs, and laboratory practices, and more consistency and collaboration between researchers would lead to greater clarity. The ambitious targets outlined in the World Health Organization End TB Strategy will only be met through a better understanding of all aspects of child TB, including the substantial impact of coinfections.

Human herpesvirus-encoded MicroRNA in host-pathogen interaction

Human herpesviruses (HHV) are ubiquitous, linear dsDNA viruses that establish lifelong latency, disrupted by sporadic reactivation. HHV have evolved diverse ingenious mechanisms to evade robust host defenses. Incorporation of unique stem loop sequences that generate viral microRNAs (v-miRs) exemplifies one such evolutionary adaptation in HHV. These noncoding RNAs can control cellular and viral transcriptomes highlighting their ability in shaping host-HHV interactions. We summarize recent developments in functional characterization of HHV-encoded miRNAs in shaping the outcome of host-pathogen interaction. Non-immunogenic dissemination of v-miRs through exosomes confer added advantage to HHV in incessant modulation of host microenvironment. This review delineates the mechanistic role of v-miRs in facilitating viral persistence and tropism by targeting genes associated with cellular (apoptosis, angiogenesis, cell migration, etc.) and viral life cycle (latency, lytic and reactivation). Burgeoning evidences indicate plausible association of v-miRs in various immune-mediated diseases (nasopharyngeal carcinoma, neurological disorders, periodontal diseases, etc.) and herpesvirus-related malignancies indicating their broad-spectrum impact on host cellular pathways. We propose to exploit tisssue and systemic levels of v-miRs as diagnostic and prognostic markers for cancers and immune-mediated diseases. Therapeutic targeting of v-miRs will advance the promising outcomes of preclinical discoveries to bedside application.

Association between cytomegalovirus infection, reduced gray matter volume, and resting-state functional hypoconnectivity in major depressive disorder: a replication and extension

Human cytomegalovirus (HCMV) is a neurotropic herpes virus known to cause neuropathology in patients with impaired immunity. Previously, we reported a reduction in the gray matter volume (GMV) of several brain regions in two independent samples of participants who were seropositive for HCMV (HCMV+) compared to matched participants who were seronegative for HCMV (HCMV-). In addition to an independent replication of the GMV findings, this study aimed to examine whether HCMV+ was associated with differences in resting-state functional connectivity (rsfMRI-FC). After balancing on 11 clinical/demographic variables using inverse probability of treatment weighting (IPTW), GMV and rsfMRI-FC were obtained from 99 participants with major depressive disorder (MDD) who were classified into 42 HCMV+ and 57 HCMV- individuals. Relative to the HCMV- group, the HCMV+ group showed a significant reduction of GMV in nine cortical regions. Volume reduction in the right lateral orbitofrontal cortex (standardized beta coefficient (SBC) = -0.32, [95%CI, -0.62 to -0.02]) and the left pars orbitalis (SBC = -0.34, [95%CI, -0.63 to -0.05]) in the HCMV+ group was also observed in the previous study. Regardless of the parcellation method or analytical approach, relative to the HCMV- group, the HCMV+ group showed hypoconnectivity between the hubs of the sensorimotor network (bilateral postcentral gyrus) and the hubs of the salience network (bilateral insula) with effect sizes ranging from SBC = -0.57 to -0.99. These findings support the hypothesis that a positive HCMV serostatus is associated with altered connectivity of regions that are important for stress and affective processing and further supports a possible etiological role of HCMV in depression.

Human Immunodeficiency Virus (HIV) and Human Cytomegalovirus (HCMV) Coinfection of Infant Tonsil Epithelium May Synergistically Promote both HIV-1 and HCMV Spread and Infection

Mother-to-child transmission (MTCT) of human immunodeficiency virus type 1 (HIV-1) and human cytomegalovirus (HCMV) may occur during pregnancy, labor, or breastfeeding. These viruses from amniotic fluid, cervicovaginal secretions, and breast milk may simultaneously interact with oropharyngeal and tonsil epithelia; however, the molecular mechanism of HIV-1 and HCMV cotransmission through the oral mucosa and its role in MTCT are poorly understood. To study the molecular mechanism of HIV-1 and HCMV MTCT via oral epithelium, we established polarized infant tonsil epithelial cells and polarized-oriented ex vivo tonsil tissue explants. Using these models, we showed that cell-free HIV-1 and its proteins gp120 and tat induce the disruption of tonsil epithelial tight junctions and increase paracellular permeability, which facilitates HCMV spread within the tonsil mucosa. Inhibition of HIV-1 gp120-induced upregulation of mitogen-activated protein kinase (MAPK) and NF-κB signaling in tonsil epithelial cells, reduces HCMV infection, indicating that HIV-1-activated MAPK and NF-κB signaling may play a critical role in HCMV infection of tonsil epithelium. HCMV infection of tonsil epithelial cells also leads to the disruption of tight junctions and increases paracellular permeability, facilitating HIV-1 paracellular spread into tonsil mucosa. HCMV-promoted paracellular spread of HIV-1 increases its accessibility to tonsil CD4 T lymphocytes, macrophages, and dendritic cells. HIV-1-enhanced HCMV paracellular spread and infection of epithelial cells subsequently leads to the spread of HCMV to tonsil macrophages and dendritic cells. Our findings revealed that HIV-1- and HCMV-induced disruption of infant tonsil epithelial tight junctions promotes MTCT of these viruses through tonsil mucosal epithelium, and therapeutic intervention for both HIV-1 and HCMV infection may substantially reduce their MTCT. IMPORTANCE Most HIV-1 and HCMV MTCT occurs in infancy, and the cotransmission of these viruses may occur via infant oropharyngeal and tonsil epithelia, which are the first biological barriers for viral pathogens. We have shown that HIV-1 and HCMV disrupt epithelial junctions, reducing the barrier functions of epithelia and thus allowing paracellular penetration of both viruses via mucosal epithelia. Subsequently, HCMV infects epithelial cells, macrophages, and dendritic cells, and HIV-1 infects CD4⁺ lymphocytes, macrophages, and dendritic cells. Infection of these cells in HCMV- and HIV-1-coinfected tonsil tissues is much higher than that by HCMV or HIV-1 infection alone, promoting their MTCT at its initial stages via infant oropharyngeal and tonsil epithelia.

Cytomegalovirus mediates expansion of IL-15-responsive innate-memory cells with SIV killing function

Interindividual immune variability is driven predominantly by environmental factors, including exposure to chronic infectious agents such as cytomegalovirus (CMV). We investigated the effects of rhesus CMV (RhCMV) on composition and function of the immune system in young macaques. Within months of infection, RhCMV was associated with impressive changes in antigen presenting cells, T cells, and NK cells-and marked expansion of innate-memory CD8+ T cells. These cells express high levels of NKG2A/C and the IL-2 and IL-15 receptor beta chain, CD122. IL-15 was sufficient to drive differentiation of the cells in vitro and in vivo. Expanded NKG2A/C+CD122+CD8+ T cells in RhCMV-infected macaques, but not their NKG2-negative counterparts, were endowed with cytotoxicity against class I-deficient K562 targets and prompt IFN-γ production in response to stimulation with IL-12 and IL-18. Because RhCMV clone 68-1 forms the viral backbone of RhCMV-vectored SIV vaccines, we also investigated immune changes following administration of RhCMV 68-1-vectored SIV vaccines. These vaccines led to impressive expansion of NKG2A/C+CD8+ T cells with capacity to inhibit SIV replication ex vivo. Thus, CMV infection and CMV-vectored vaccination drive expansion of functional innate-like CD8 cells via host IL-15 production, suggesting that innate-memory expansion could be achieved by other vaccine platforms expressing IL-15.

Evasion of the Host Immune Response by Betaherpesviruses

The human immune system boasts a diverse array of strategies for recognizing and eradicating invading pathogens. Human betaherpesviruses, a highly prevalent subfamily of viruses, include human cytomegalovirus (HCMV), human herpesvirus (HHV) 6A, HHV-6B, and HHV-7. These viruses have evolved numerous mechanisms for evading the host response. In this review, we will highlight the complex interplay between betaherpesviruses and the human immune response, focusing on protein function. We will explore methods by which the immune system first responds to betaherpesvirus infection as well as mechanisms by which viruses subvert normal cellular functions to evade the immune system and facilitate viral latency, persistence, and reactivation. Lastly, we will briefly discuss recent advances in vaccine technology targeting betaherpesviruses. This review aims to further elucidate the dynamic interactions between betaherpesviruses and the human immune system.

Neutrophil Extracellular Traps Affecting Cardiovascular Health in Infectious and Inflammatory Diseases

Neutrophil extracellular traps (NETs) are web-like structures of decondensed extracellular chromatin fibers and neutrophil granule proteins released by neutrophils. NETs participate in host immune defense by entrapping pathogens. They are pro-inflammatory in function, and they act as an initiator of vascular coagulopathies by providing a platform for the attachment of various coagulatory proteins. NETs are diverse in their ability to alter physiological and pathological processes including infection and inflammation. In this review, we will summarize recent findings on the role of NETs in bacterial/viral infections associated with vascular inflammation, thrombosis, atherosclerosis and autoimmune disorders. Understanding the complex role of NETs in bridging infection and chronic inflammation as well as discussing important questions related to their contribution to pathologies outlined above may pave the way for future research on therapeutic targeting of NETs applicable to specific infections and inflammatory disorders.

Detection of Cytomegalovirus Interleukin 10 (cmvIL-10) by Enzyme-Linked Immunosorbent Assay (ELISA)

Since its introduction in 1971, the enzyme-linked immunosorbent assay (ELISA) has revolutionized medicine by enabling detection of both antigens and antibodies in a variety of samples. We describe here a customized sandwich ELISA developed for the detection of Human Cytomegalovirus interleukin-10 (cmvIL-10). CmvIL-10 is a virally encoded cytokine and ortholog of human interleukin 10 (hIL-10). While cmvIL-10 and hIL-10 are similar in structure and function, overall amino acid sequence identity is only 27%, resulting in antigenically distinct proteins. The cmvIL-10 ELISA is specific and does not detect hIL-10. The assay is sensitive enough to detect cmvIL-10 in both culture supernatants and patient serum. The ability to quantify cmvIL-10 levels during HCMV infection could provide valuable information about immune evasion strategies and viral control of host signaling pathways.

Triple RNA-Seq Reveals Synergy in a Human Virus-Fungus Co-infection Model

High-throughput RNA sequencing (RNA-seq) is routinely applied to study diverse biological processes; however, when performed separately on interacting organisms, systemic noise intrinsic to RNA extraction, library preparation, and sequencing hampers the identification of cross-species interaction nodes. Here, we develop triple RNA-seq to simultaneously detect transcriptomes of monocyte-derived dendritic cells (moDCs) infected with the frequently co-occurring pulmonary pathogens Aspergillus fumigatus and human cytomegalovirus (CMV). Comparing expression patterns after co-infection with those after single infections, our data reveal synergistic effects and mutual interferences between host responses to the two pathogens. For example, CMV attenuates the fungus-mediated activation of pro-inflammatory cytokines through NF-κB (nuclear factor κB) and NFAT (nuclear factor of activated T cells) cascades, while A. fumigatus impairs viral clearance by counteracting viral nucleic acid-induced activation of type I interferon signaling. Together, the analytical power of triple RNA-seq proposes molecular hubs in the differential moDC response to fungal/viral single infection or co-infection that contribute to our understanding of the etiology and, potentially, clearance of post-transplant infections.

Control of Cytokines in Latent Cytomegalovirus Infection

Human cytomegalovirus (HCMV) has evolved a number of mechanisms for long-term co-existence within its host. HCMV infects a wide range of cell types, including fibroblasts, epithelial cells, monocytes, macrophages, dendritic cells, and myeloid progenitor cells. Lytic infection, with the production of infectious progeny virions, occurs in differentiated cell types, while undifferentiated myeloid precursor cells are the primary site of latent infection. The outcome of HCMV infection depends partly on the cell type and differentiation state but is also influenced by the composition of the immune environment. In this review, we discuss the role of early interactions between HCMV and the host immune system, particularly cytokine and chemokine networks, that facilitate the establishment of lifelong latent infection. A better understanding of these cytokine signaling pathways could lead to novel therapeutic targets that might prevent latency or eradicate latently infected cells.

Immune Escape in Glioblastoma Multiforme and the Adaptation of Immunotherapies for Treatment

Glioblastoma multiforme (GBM) is the most frequently occurring primary brain tumor and has a very poor prognosis, with only around 5% of patients surviving for a period of 5 years or more after diagnosis. Despite aggressive multimodal therapy, consisting mostly of a combination of surgery, radiotherapy, and temozolomide chemotherapy, tumors nearly always recur close to the site of resection. For the past 15 years, very little progress has been made with regards to improving patient survival. Although immunotherapy represents an attractive therapy modality due to the promising pre-clinical results observed, many of these potential immunotherapeutic approaches fail during clinical trials, and to date no immunotherapeutic treatments for GBM have been approved. As for many other difficult to treat cancers, GBM combines a lack of immunogenicity with few mutations and a highly immunosuppressive tumor microenvironment (TME). Unfortunately, both tumor and immune cells have been shown to contribute towards this immunosuppressive phenotype. In addition, current therapeutics also exacerbate this immunosuppression which might explain the failure of immunotherapy-based clinical trials in the GBM setting. Understanding how these mechanisms interact with one another, as well as how one can increase the anti-tumor immune response by addressing local immunosuppression will lead to better clinical results for immune-based therapeutics. Improving therapeutic delivery across the blood brain barrier also presents a challenge for immunotherapy and future therapies will need to consider this. This review highlights the immunosuppressive mechanisms employed by GBM cancers and examines potential immunotherapeutic treatments that can overcome these significant immunosuppressive hurdles.

Cytokine-Targeted Therapeutics for KSHV-Associated Disease

Kaposi's sarcoma-associated herpesvirus (KSHV) also known as human herpesvirus 8 (HHV-8), is linked to several human malignancies including Kaposi sarcoma (KS), primary effusion lymphoma (PEL), multicentric Castleman's disease (MCD) and recently KSHV inflammatory cytokine syndrome (KICS). As with other diseases that have a significant inflammatory component, current therapy for KSHV-associated disease is associated with significant off-target effects. However, recent advances in our understanding of the pathogenesis of KSHV have produced new insight into the use of cytokines as potential therapeutic targets. Better understanding of the role of cytokines during KSHV infection and tumorigenesis may lead to new preventive or therapeutic strategies to limit KSHV spread and improve clinical outcomes. The cytokines that appear to be promising candidates as KSHV antiviral therapies include interleukins 6, 10, and 12 as well as interferons and tumor necrosis factor-family cytokines. This review explores our current understanding of the roles that cytokines play in promoting KSHV infection and tumorigenesis, and summarizes the current use of cytokines as therapeutic targets in KSHV-associated diseases.

Identification of a novel signaling complex containing host chemokine receptor CXCR4, Interleukin-10 receptor, and human cytomegalovirus US27

Human cytomegalovirus (HCMV) is a widespread herpesvirus that establishes latency in myeloid cells and persists by manipulating immune signaling. Chemokine receptor CXCR4 and its ligand CXCL12 regulate movement of myeloid progenitors into bone marrow and out into peripheral tissues. HCMV amplifies CXCL12-CXCR4 signaling through viral chemokine receptor US27 and cmvIL-10, a viral cytokine that binds the cellular IL-10 receptor (IL-10R), but precisely how these viral proteins influence CXCR4 is unknown. We used the proximity ligation assay (PLA) to examine association of CXCR4, IL-10R, and US27 in both transfected and HCMV-infected cells. CXCR4 and IL-10R colocalized to discrete clusters, and treatment with CXCL12 and cmvIL-10 dramatically increased receptor clustering and calcium flux. US27 was associated with CXCR4 and IL-10R in PLA clusters and further enhanced cluster formation and calcium signaling. These results indicate that CXCR4, IL-10R, and US27 form a novel virus-host signaling complex that enhances CXCL12 signaling during HCMV infection.

Biology and therapeutic potential of interleukin-10

The authors review the molecular mechanisms regulating IL-10 production and response and describe classic and novel functions of IL-10 in immune and non-immune cells. They further discuss the therapeutic potential of IL-10 in different diseases and the outstanding questions underlying an effective application of IL-10 in clinical settings.

The cytokine IL-10 is a key anti-inflammatory mediator ensuring protection of a host from over-exuberant responses to pathogens and microbiota, while playing important roles in other settings as sterile wound healing, autoimmunity, cancer, and homeostasis. Here we discuss our current understanding of the regulation of IL-10 production and of the molecular pathways associated with IL-10 responses. In addition to IL-10’s classic inhibitory effects on myeloid cells, we also describe the nonclassic roles attributed to this pleiotropic cytokine, including how IL-10 regulates basic processes of neural and adipose cells and how it promotes CD8 T cell activation, as well as epithelial repair. We further discuss its therapeutic potential in the context of different diseases and the outstanding questions that may help develop an effective application of IL-10 in diverse clinical settings.

Human Cytomegalovirus Interleukin 10 Homologs: Facing the Immune System

Human Cytomegalovirus (HCMV) can cause a variety of health disorders that can lead to death in immunocompromised individuals and neonates. The HCMV lifecycle comprises both a lytic (productive) and a latent (non-productive) phase. HCMV lytic infection occurs in a wide range of terminally differentiated cell types. HCMV latency has been less well-studied, but one characterized site of latency is in precursor cells of the myeloid lineage. All known viral genes are expressed during a lytic infection and a subset of these are also transcribed during latency. The UL111A gene which encodes the viral IL-10, a homolog of the human IL-10, is one of these genes. During infection, different transcript isoforms of UL111A are generated by alternative splicing. The most studied of the UL111A isoforms are cmvIL-10 (also termed the "A" transcript) and LAcmvIL-10 (also termed the "B" transcript), the latter being a well-characterized latency associated transcript. Both isoforms can downregulate MHC class II, however they differ in a number of other immunomodulatory properties, such as the ability to bind the IL10 receptor and induce signaling through STAT3. There are also a number of other isoforms which have been identified which are expressed by differential splicing during lytic infection termed C, D, E, F, and G, although these have been less extensively studied. HCMV uses the viral IL-10 proteins to manipulate the immune system during lytic and latent phases of infection. In this review, we will discuss the literature on the viral IL-10 transcripts identified to date, their encoded proteins and the structures of these proteins as well as the functional properties of all the different isoforms of viral IL-10.

SARS-CoV-2 infection: The role of cytokines in COVID-19 disease

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A wide range of cytokines are involved in the development of COVID-19 disease.

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Some of these biomolecules are related to the progression and even to the prognosis of the infection.

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Findings on the role of cytokine storm associated with SARS-CoV-2 infection can be useful in order to manage this highly virulent disease.

COVID-19 disease, caused by infection with SARS-CoV-2, is related to a series of physiopathological mechanisms that mobilize a wide variety of biomolecules, mainly immunological in nature. In the most severe cases, the prognosis can be markedly worsened by the hyperproduction of mainly proinflammatory cytokines, such as IL-1, IL-6, IL-12, IFN-γ, and TNF-α, preferentially targeting lung tissue. This study reviews published data on alterations in the expression of different cytokines in patients with COVID-19 who require admission to an intensive care unit. Data on the implication of cytokines in this disease and their effect on outcomes will support the design of more effective approaches to the management of COVID-19.

Ocular cytomegalovirus latency exacerbates the development of choroidal neovascularization

Age-related macular degeneration (AMD) is a complex, multifactorial, progressive disease which represents a leading cause of irreversible visual impairment and blindness in older individuals. Human cytomegalovirus (HCMV), which infects 50-80% of humans, is usually acquired during early life and persists in a latent state for the life of the individual. In view of its previously described pro-angiogenic properties, we hypothesized that cytomegalovirus might be a novel risk factor for progression to an advanced form, neovascular AMD, which is characterized by choroidal neovascularization (CNV). The purpose of this study was to investigate if latent ocular murine cytomegalovirus (MCMV) infection exacerbated the development of CNV in vascular endothelial growth factor (VEGF)-overexpressing VEGF-A^hyper mice. Here we show that neonatal infection with MCMV resulted in dissemination of virus to various organs throughout the body including the eye, where it localized principally to the choroid in both VEGF-overexpressingVEGF-A^hyper and wild-type(WT) 129 mice. By 6 months post-infection, no replicating virus was detected in eyes and extraocular tissues, although virus DNA was still present in all eyes and extraocular tissues of both VEGF-A^hyper and WT mice. Expression of MCMV immediate early (IE) 1 mRNA was detected only in latently infected eyes of VEGF-A^hyper mice, but not in eyes of WT mice. Significantly increased CNV was observed in eyes of MCMV-infected VEGF-A^hyper mice compared to eyes of uninfected VEGF-A^hyper mice, while no CNV lesions were observed in eyes of either infected or uninfected WT mice. Protein levels of several inflammatory/angiogenic factors, particularly VEGF and IL-6, were significantly higher in eyes of MCMV-infected VEGF-A^hyper mice, compared to uninfected controls. Initial studies of ocular tissue from human cadavers revealed that HCMV DNA was present in four choroid/retinal pigment epithelium samples from 24 cadavers. Taken together, our data suggest that ocular HCMV latency could be a significant risk factor for the development of AMD. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Human Immunodeficiency Virus Exposure but Not Early Cytomegalovirus Infection Is Associated With Increased Hospitalization and Decreased Memory T-Cell Responses to Tetanus Vaccine

BACKGROUND

Human immunodeficiency virus (HIV)-exposed, uninfected (HEU) infants experience high rates of infectious morbidity. We hypothesized that early cytomegalovirus (CMV) infection was associated with increased hospitalization rates and decreased vaccine responses in HEU compared with HIV-unexposed (HUU) infants.

METHODS

Among infants enrolled in the Tshipidi study in Botswana, we determined CMV infection status by 6 months of age and compared hospitalization rates and responses to tetanus and Bacille Calmette-Guérin vaccines among HEU and HUU vaccinees.

RESULTS

Fifteen of 226 (6.6%) HEU infants and 17 (19.3%) of 88 HUU infants were CMV-infected by 6 months. The HEU infants were approximately 3 times as likely to be hospitalized compared with HUU infants (P = .02). The HEU peripheral blood cells produced less interleukin (IL)-2 (P = .004), but similar amounts of interferon-γ, after stimulation with tetanus toxoid. Antitetanus immunoglobulin G titers were similar between groups. Cellular responses to purified protein derivative stimulation did not differ between groups. Maternal receipt of 3-drug antiretroviral therapy compared with zidovudine was associated with increased IL-2 expression after tetanus toxoid stimulation. The infants' CMV infection status was not associated with clinical or vaccine response outcomes.

CONCLUSIONS

We observed that increased rates of hospitalization and decreased memory T-cell responses to tetanus vaccine were associated with HIV exposure and incomplete treatment of maternal HIV infection, but not early CMV infection.

Cytomegalovirus-vectored vaccines for HIV and other pathogens

: The use of cytomegalovirus (CMV) as a vaccine vector to express antigens against multiple infectious diseases, including simian immunodeficiency virus, Ebola virus, plasmodium, and mycobacterium tuberculosis, in rhesus macaques has generated extraordinary levels of protective immunity against subsequent pathogenic challenge. Moreover, the mechanisms of immune protection have altered paradigms about viral vector-mediated immunity against ectopically expressed vaccine antigens. Further optimization of CMV-vectored vaccines, particularly as this approach moves to human clinical trials will be augmented by a more complete understanding of how CMV engenders mechanisms of immune protection. This review summarizes the particulars of the specific CMV vaccine vector that has been used to date (rhesus CMV strain 68-1) in relation to CMV natural history.

Human Cytomegalovirus Infection Induces High Expression of Prolactin and Prolactin Receptors in Ovarian Cancer

One of the potential biomarkers for ovarian cancer patients is high serum level of prolactin (PRL), which is a growth factor that may promote tumor cell growth. The prolactin receptor (PRLR) and human cytomegalovirus (HCMV) proteins are frequently detected in ovarian tumor tissue specimens, but the potential impact of HCMV infection on the PRL system have so far not been investigated. In this study, HCMV’s effects on PRL and PRLR expression were assessed in infected ovarian cancer cells (SKOV3) by PCR and Western blot techniques. The levels of both PRL and PRLR transcripts as well as the corresponding proteins were highly increased in HCMV-infected SKOV3 cells. Tissue specimens obtained from 10 patients with ovarian cancer demonstrated high expression of PRLR, HCMV-IE, and pp65 proteins. Extensive expression of PRLR was detected in all examined ovarian tumor tissue specimens except for one from a patient who had focal expression of PRLR and this patient was HCMV-negative in her tumor. In conclusion, PRL and PRLR were induced to high levels in HCMV-infected ovarian cancer cells and PRLR expression was extensively detected in HCMV-infected ovarian tissue specimens. Highly induced PRL and PRLR by HCMV infection may be of relevance for the oncomodulatory role of this virus in ovarian cancer.

Herpesviral Latency-Common Themes

Latency establishment is the hallmark feature of herpesviruses, a group of viruses, of which nine are known to infect humans. They have co-evolved alongside their hosts, and mastered manipulation of cellular pathways and tweaking various processes to their advantage. As a result, they are very well adapted to persistence. The members of the three subfamilies belonging to the family Herpesviridae differ with regard to cell tropism, target cells for the latent reservoir, and characteristics of the infection. The mechanisms governing the latent state also seem quite different. Our knowledge about latency is most complete for the gammaherpesviruses due to previously missing adequate latency models for the alpha and beta-herpesviruses. Nevertheless, with advances in cell biology and the availability of appropriate cell-culture and animal models, the common features of the latency in the different subfamilies began to emerge. Three criteria have been set forth to define latency and differentiate it from persistent or abortive infection: 1) persistence of the viral genome, 2) limited viral gene expression with no viral particle production, and 3) the ability to reactivate to a lytic cycle. This review discusses these criteria for each of the subfamilies and highlights the common strategies adopted by herpesviruses to establish latency.

Overexpression of the human cytomegalovirus UL111A is correlated with favorable survival of patients with gastric cancer and changes T-cell infiltration and suppresses carcinogenesis

Purpose

We previously found that human cytomegalovirus (HCMV) infection is associated with gastric cancer (GC) development. UL111A plays a role during HCMV productive or latent infection. However, UL111A expression profiles in GC tissues and their relationship with this disease are unknown.

Methods

PCR and nested RT-PCR were performed to verify UL111A expression in 71 GC tissues and its transcripts in 16 UL111A-positive GC samples. UL111A expression levels in GC patients were evaluated by immunohistochemistry on a tissue microarray for 620 GC patients. The correlations among UL111A expression levels, clinicopathological characteristics, and prognosis were analyzed. Further, the effects of overexpression of latency-associated viral interleukin-10 (LAcmvIL-10) and cmvIL-10 on GC cell proliferation, colony formation, migration, and invasion were assessed.

Results

The UL111A detection rate in GC tissues was 32.4% (23/71) and that of its mRNA expression was 68.75% (11/16). High expression of UL111A was also related to better overall and disease-free survival in GC patients. GC patients with TNM II/III stage expressing higher UL111A levels might benefit from adjuvant chemotherapy (ACT) after surgery. Moreover, high UL111A expression was also associated with increased CD4+ , CD8+ T-lymphocyte and Foxp3+ T-cell infiltration. In vitro assays further demonstrated that LAcmvIL-10 and cmvIL-10 overexpression inhibits GC cell line proliferation, colony formation, migration, and invasion.

Conclusions

High UL111A expression changes the number of infiltrating T cells and is associated with favorable survival. Therefore, UL111A could be used as an independent prognostic biomarker and might be a potential therapeutic target for GC.

Electronic supplementary material

The online version of this article (10.1007/s00432-019-03092-x) contains supplementary material, which is available to authorized users.

Cytomegalovirus Retinitis in HIV and Non-HIV Individuals

Cytomegalovirus retinitis (CMVR) is a severe, vision-threatening disease that primarily affects immunosuppressed patients. CMVR is the most common ocular opportunistic infection in human immunodeficiency virus (HIV) infected patients and is the leading cause of blindness in this group; however, the incidence of CMVR in HIV patients has dramatically decreased with antiretroviral therapy. Other causes of immunosuppression, including organ transplantation, hematologic malignancies, and iatrogenic immunosuppression, can also lead to the development of CMVR. Herein, we describe the pathogenesis of CMVR and compare clinical features, epidemiology, and risk factors in HIV and non-HIV infected individuals with CMVR.

Tongue sole (Cynoglossus semilaevis) interleukin 10 plays a negative role in the immune response against bacterial infection

Interleukin-10 (IL-10) is a pleiotropic cytokine and plays a crucial role in immunity. In the current study, we examined the expression patterns and biological functions of tongue sole Cynoglossus semilaevis IL-10 (CsIL-10). CsIL-10 is composed of 186 amino acid residues and shares 46.3%-71.7% identities with other teleost IL-10. Csil-10 expression occurred in multiple tissues and was regulated by bacterial infection. Recombinant CsIL-10 (rCsIL-10) in the form of a dimer bound to a wide range of bacterial species but did not affect bacterial growth. rCsIL-10 could interact with peripheral blood leukocytes (PBL) and significantly reduce the phagocytic activity, ROS production, and apoptosis of PBL. When injected in vivo, rCsIL-10 significantly suppressed the expression of proinflammatory cytokines and promoted bacterial dissemination in tongue sole tissues. Consistently, knockdown of Csil-10 significantly inhibited bacterial infection in tongue sole. Taken together, these results indicate that CsIL-10 plays a negative regulatory role in the immune response against bacterial infection.

Viral Hormones: Expanding Dimensions in Endocrinology

Viruses have developed different mechanisms to manipulate their hosts, including the process of viral mimicry in which viruses express important host proteins. Until recently, examples of viral mimicry were limited to mimics of growth factors and immunomodulatory proteins. Using a comprehensive bioinformatics approach, we have shown that viruses possess the DNA/RNA with potential to encode 16 different peptides with high sequence similarity to human peptide hormones and metabolically important regulatory proteins. We have characterized one of these families, the viral insulin/IGF-1-like peptides (VILPs), which we identified in four members of the Iridoviridae family. VILPs can bind to human insulin and IGF-1 receptors and stimulate classic postreceptor signaling pathways. Moreover, VILPs can stimulate glucose uptake in vitro and in vivo and stimulate DNA synthesis. DNA sequences of some VILP-carrying viruses have been identified in the human enteric virome. In addition to VILPs, sequences with homology to 15 other peptide hormones or cytokines can be identified in viral DNA/RNA sequences, some with a very high identity to hormones. Recent data by others has identified a peptide that resembles and mimics α-melanocyte-stimulating hormone's anti-inflammatory effects in in vitro and in vivo models. Taken together, these studies reveal novel mechanisms of viral and bacterial pathogenesis in which the microbe can directly target or mimic the host endocrine system. These findings also introduce the concept of a system of microbial hormones that provides new insights into the evolution of peptide hormones, as well as potential new roles of microbial hormones in health and disease.

Human cytomegalovirus induces and exploits Roquin to counteract the IRF1-mediated antiviral state

RNA represents a pivotal component of host-pathogen interactions. Human cytomegalovirus (HCMV) infection causes extensive alteration in host RNA metabolism, but the functional relationship between the virus and cellular RNA processing remains largely unknown. Through loss-of-function screening, we show that HCMV requires multiple RNA-processing machineries for efficient viral lytic production. In particular, the cellular RNA-binding protein Roquin, whose expression is actively stimulated by HCMV, plays an essential role in inhibiting the innate immune response. Transcriptome profiling revealed Roquin-dependent global down-regulation of proinflammatory cytokines and antiviral genes in HCMV-infected cells. Furthermore, using cross-linking immunoprecipitation (CLIP)-sequencing (seq), we identified IFN regulatory factor 1 (IRF1), a master transcriptional activator of immune responses, as a Roquin target gene. Roquin reduces IRF1 expression by directly binding to its mRNA, thereby enabling suppression of a variety of antiviral genes. This study demonstrates how HCMV exploits host RNA-binding protein to prevent a cellular antiviral response and offers mechanistic insight into the potential development of CMV therapeutics.

Development of a Human Cytomegalovirus (HCMV)-Based Therapeutic Cancer Vaccine Uncovers a Previously Unsuspected Viral Block of MHC Class I Antigen Presentation

Human cytomegalovirus (HCMV) induces a uniquely high frequency of virus-specific effector/memory CD8+ T-cells, a phenomenon termed “memory inflation”. Thus, HCMV-based vaccines are particularly interesting in order to stimulate a sustained and strong cellular immune response against cancer. Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor with high lethality and inevitable relapse. The current standard treatment does not significantly improve the desperate situation underlining the urgent need to develop novel approaches. Although HCMV is highly fastidious with regard to species and cell type, GBM cell lines are susceptible to HCMV. In order to generate HCMV-based therapeutic vaccine candidates, we deleted all HCMV-encoded proteins (immunoevasins) that interfere with MHC class I presentation. The aim being to use the viral vector as an adjuvant for presentation of endogenous tumor antigens, the presentation of high levels of vector-encoded neoantigens and finally the repurposing of bystander HCMV-specific CD8+ T cells to fight the tumor. As neoantigen, we exemplarily used the E6 and E7 proteins of human papillomavirus type 16 (HPV-16) as a non-transforming fusion protein (E6/E7) that covers all relevant antigenic peptides. Surprisingly, GBM cells infected with E6/E7-expressing HCMV-vectors failed to stimulate E6-specific T cells despite high level expression of E6/E7 protein. Further experiments revealed that MHC class I presentation of E6/E7 is impaired by the HCMV-vector although it lacks all known immunoevasins. We also generated HCMV-based vectors that express E6-derived peptide fused to HCMV proteins. GBM cells infected with these vectors efficiently stimulated E6-specific T cells. Thus, fusion of antigenic sequences to HCMV proteins is required for efficient presentation via MHC class I molecules during infection. Taken together, these results provide the preclinical basis for development of HCMV-based vaccines and also reveal a novel HCMV-encoded block of MHC class I presentation.

Human cytomegalovirus infection is correlated with enhanced cyclooxygenase-2 and 5-lipoxygenase protein expression in breast cancer

Purpose

While enhanced expression of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LO) and their derived metabolites is associated with breast cancer (BC) risk, the precise link between BC carcinogenesis and enhanced inflammatory activity remains to be clarified. Human Cytomegalovirus (HCMV) may induce expression of COX-2 and 5-LO and is frequently found in breast cancer biopsies. Thus, we investigated whether there is an association between HCMV proteins and expression of COX-2 and 5-LO in human BC tissue and BC cell lines.

Materials and methods

Paraffin embedded biopsies obtained from 49 patients with breast cancer and 26 tissue samples from adjacent, benign breast tissues were retrospectively examined for HCMV-immediate early (IE), HCMV-Late (LA), COX-2, and 5-LO proteins by immunohistochemistry. In vitro, uninfected and HCMV-infected BC cell lines were examined for COX-2 and 5-LO transcripts and proteins by PCR and flow cytometry.

Results

Extensive expression of COX-2, 5-LO and HCMV-IE proteins were preferentially detected in BC samples. We found a statistically significant concordant correlation between extensive HCMV-IE and COX-2 (P < 0.0001) as well as with HCMV-IE and 5-LO (P = 0.0003) in infiltrating BC. In vitro, HCMV infection induced COX-2 and 5-LO transcripts and COX-2 proteins in MCF-7 cells (P =0.008, P =0.018, respectively). In MDA-MB-231 cells that already had high base line levels of COX-2 expression, HCMV induced both COX-2 and 5-LO proteins but not transcripts.

Conclusion

Our findings demonstrate a significant correlation between extensive HCMV-IE protein expression and overexpression of COX-2 and 5-LO in human breast cancer.

Electronic supplementary material

The online version of this article (10.1007/s00432-019-02946-8) contains supplementary material, which is available to authorized users.