Known unknowns: how might the persistent herpesvirome shape immunity and aging?

Unveiling the Impact of Epstein-Barr Virus on the Risk of Prostate Cancer: A Mendelian Randomization Study

Given the consistent detection of Epstein-Barr virus (EBV) in prostate tissues and the clinical evidence suggesting its involvement in prostate cancer (PCa), the potential association between EBV infection and PCa warrants further investigation. This study aimed to assess the causal relationship between EBV infection and PCa using Mendelian randomization (MR). We utilized data from a publicly available genome-wide association study (GWAS) on PCa, alongside data on five serum anti-EBV virus-related antibodies. Our findings indicate a potential causal link between serum EBV EA-D antibody levels and an increased risk of PCa. These results highlight the need for additional research to elucidate the mechanisms by which EBV may contribute to the progression of PCa, potentially offering new insights into its pathogenesis and therapeutic targets.

Herpesvirus Infection of Endothelial Cells as a Systemic Pathological Axis in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Understanding the pathophysiology of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is critical for advancing treatment options. This review explores the novel hypothesis that a herpesvirus infection of endothelial cells (ECs) may underlie ME/CFS symptomatology. We review evidence linking herpesviruses to persistent EC infection and the implications for endothelial dysfunction, encompassing blood flow regulation, coagulation, and cognitive impairment-symptoms consistent with ME/CFS and Long COVID. This paper provides a synthesis of current research on herpesvirus latency and reactivation, detailing the impact on ECs and subsequent systemic complications, including latent modulation and long-term maladaptation. We suggest that the chronicity of ME/CFS symptoms and the multisystemic nature of the disease may be partly attributable to herpesvirus-induced endothelial maladaptation. Our conclusions underscore the necessity for further investigation into the prevalence and load of herpesvirus infection within the ECs of ME/CFS patients. This review offers conceptual advances by proposing an endothelial infection model as a systemic mechanism contributing to ME/CFS, steering future research toward potentially unexplored avenues in understanding and treating this complex syndrome.

Determinants of COVID-19 Disease Severity-Lessons from Primary and Secondary Immune Disorders including Cancer

At the beginning of the COVID-19 pandemic, patients with primary and secondary immune disorders-including patients suffering from cancer-were generally regarded as a high-risk population in terms of COVID-19 disease severity and mortality. By now, scientific evidence indicates that there is substantial heterogeneity regarding the vulnerability towards COVID-19 in patients with immune disorders. In this review, we aimed to summarize the current knowledge about the effect of coexistent immune disorders on COVID-19 disease severity and vaccination response. In this context, we also regarded cancer as a secondary immune disorder. While patients with hematological malignancies displayed lower seroconversion rates after vaccination in some studies, a majority of cancer patients' risk factors for severe COVID-19 disease were either inherent (such as metastatic or progressive disease) or comparable to the general population (age, male gender and comorbidities such as kidney or liver disease). A deeper understanding is needed to better define patient subgroups at a higher risk for severe COVID-19 disease courses. At the same time, immune disorders as functional disease models offer further insights into the role of specific immune cells and cytokines when orchestrating the immune response towards SARS-CoV-2 infection. Longitudinal serological studies are urgently needed to determine the extent and the duration of SARS-CoV-2 immunity in the general population, as well as immune-compromised and oncological patients.

Serum Level of MMP-3 and MMP-9 in Patients with Diabetes Mellitus Type 2 Infected with Epstein-Barr Virus

Diabetes mellitus type 2 (DM2) has recently become one of the most important health problems in the world. Patients with DM2 with long-term glycaemia are more likely to become infected than the healthy population. Matrix metalloproteinases (MMPs) play a key role in tissue remodeling during various physiological processes. However, it has been reported that certain MMPs are overexpressed during the development of various human diseases. In this study, we analyzed the levels of MMP-3 and MMP-9 in the serum of DM2 patients with and without Epstein-Barr virus (EBV) infection. The study included 115 patients with DM2 hospitalized in the Internal Ward of the Masovian Specialist Hospital in Radom, Poland, who were divided into two groups: EBV-positive and EBV-negative. The levels of MMP-3 and MMP-9 were tested in the serum of patients using the ELISA method, while the presence of EBV in saliva was tested by polymerase chain reaction (PCR). The presented studies showed a significant difference in the concentration of both MMPs in diabetic patients additionally infected with EBV compared to the group of non-infected individuals. It seems that MMPs may be useful biomarkers in the diagnosis, prognosis, and monitoring of diabetes associated with EBV infection.

Herpesviruses and their genetic diversity in the blood virome of healthy individuals: effect of aging

BACKGROUND

As we age, the functioning of the human immune system declines. The results of this are increases in morbidity and mortality associated with infectious diseases, cancer, cardiovascular disease, and neurodegenerative disease in elderly individuals, as well as a weakened vaccination response. The aging of the immune system is thought to affect and be affected by the human virome, the collection of all viruses present in an individual. Persistent viral infections, such as those caused by certain herpesviruses, can be present in an individual for long periods of time without any overt pathology, yet are associated with disease in states of compromised immune function. To better understand the effects on human health of such persistent viral infections, we must first understand how the human virome changes with age. We have now analyzed the composition of the whole blood virome of 317 individuals, 21-70 years old, using a metatranscriptomic approach. Use of RNA sequencing data allows for the unbiased detection of RNA viruses and active DNA viruses.

RESULTS

The data obtained showed that Epstein-Barr virus (EBV) was the most frequently expressed virus, with other detected viruses being herpes simplex virus 1, human cytomegalovirus, torque teno viruses, and papillomaviruses. Of the 317 studied blood samples, 68 (21%) had EBV expression, whereas the other detected viruses were only detected in at most 6 samples (2%). We therefore focused on EBV in our further analyses. Frequency of EBV detection, relative EBV RNA abundance and the genetic diversity of EBV was not significantly different between age groups (21-59 and 60-70 years old). No significant correlation was seen between EBV RNA abundance and age. Deconvolution analysis revealed a significant difference in proportions of activated dendritic cells, macrophages M1, and activated mast cells between EBV expression positive and negative individuals.

CONCLUSIONS

As it is likely that the EBV RNA quantified in this work is derived from reactivation of the latent EBV virus, these data suggest that age does not affect the rate of reactivation nor the genetic landscape of EBV. These findings offer new insight on the genetic diversity of a persistent EBV infection in the long-term.

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.

How Does Epstein–Barr Virus Interact With Other Microbiomes in EBV-Driven Cancers?

The commensal microbiome refers to a large spectrum of microorganisms which mainly consists of viruses and bacteria, as well as some other components such as protozoa and fungi. Epstein–Barr virus (EBV) is considered as a common component of the human commensal microbiome due to its spread worldwide in about 95% of the adult population. As the first oncogenic virus recognized in human, numerous studies have reported the involvement of other components of the commensal microbiome in the increasing incidence of EBV-driven cancers. Additionally, recent advances have also defined the involvement of host–microbiota interactions in the regulation of the host immune system in EBV-driven cancers as well as other circumstances. The regulation of the host immune system by the commensal microbiome coinfects with EBV could be the implications for how we understand the persistence and reactivation of EBV, as well as the progression of EBV-associated cancers, since majority of the EBV persist as asymptomatic carrier. In this review, we attempt to summarize the possible mechanisms for EBV latency, reactivation, and EBV-driven tumorigenesis, as well as casting light on the role of other components of the microbiome in EBV infection and reactivation. Besides, whether novel microbiome targeting strategies could be applied for curing of EBV-driven cancer is discussed as well.

How Immunosenescence and Inflammaging May Contribute to Hyperinflammatory Syndrome in COVID-19

Aging is characterized by the dynamic remodeling of the immune system designated “immunosenescence,” and is associated with altered hematopoiesis, thymic involution, and lifelong immune stimulation by multitudinous chronic stressors, including the cytomegalovirus (CMV). Such alterations may contribute to a lowered proportion of naïve T-cells and to reduced diversity of the T-cell repertoire. In the peripheral circulation, a shift occurs towards accumulations of T and B-cell populations with memory phenotypes, and to accumulation of putatively senescent and exhausted immune cells. The aging-related accumulations of functionally exhausted memory T lymphocytes, commonly secreting pro-inflammatory cytokines, together with mediators and factors of the innate immune system, are considered to contribute to the low-grade inflammation (inflammaging) often observed in elderly people. These senescent immune cells not only secrete inflammatory mediators, but are also able to negatively modulate their environments. In this review, we give a short summary of the ways that immunosenescence, inflammaging, and CMV infection may cause insufficient immune responses, contribute to the establishment of the hyperinflammatory syndrome and impact the severity of the coronavirus disease 2019 (COVID-19) in elderly people.

Immunosenescence and inflammaging in the aging process: age-related diseases or longevity?

During aging the immune system (IS) undergoes remarkable changes that collectively are known as immunosenescence. It is a multifactorial and dynamic phenomenon that affects both natural and acquired immunity and plays a critical role in most chronic diseases in older people. For a long time, immunosenescence has been considered detrimental because it may lead to a low-grade, sterile chronic inflammation we proposed to call "inflammaging" and a progressive reduction in the ability to trigger effective antibody and cellular responses against infections and vaccinations. Recently, many scientists revised this negative meaning because it can be considered an essential adaptation/remodeling resulting from the lifelong immunological biography of single individuals from an evolutionary perspective. Inflammaging can be considered an adaptive process because it can trigger an anti-inflammatory response to counteract the age-related pro-inflammatory environment. Centenarians represent a valuable model to study the beneficial changes occurring in the IS with age. These extraordinary individuals reached the extreme limits of human life by slowing down the aging process and, in most cases, delaying, avoiding or surviving the major age-associated diseases. They indeed show a complex and heterogeneous phenotype determined by an improved ability to adapt and remodel in response to harmful stimuli. This review aims to point out the intimate relationship between immunosenescence and inflammaging and how these processes impact unsuccessful aging rather than longevity. We also describe the gut microbiota age-related changes as one of the significant triggers of inflammaging and the sex/gender differences in the immune system of the elderly, contributing to the sex/gender disparity in terms of epidemiology, pathophysiology, symptoms and severity of age-related diseases. Finally, we discuss how these phenomena could influence the susceptibility to COVID-19 infection.

Aging and Options to Halt Declining Immunity to Virus Infections

Immunosenescence is a process associated with aging that leads to dysregulation of cells of innate and adaptive immunity, which may become dysfunctional. Consequently, older adults show increased severity of viral and bacterial infections and impaired responses to vaccinations. A better understanding of the process of immunosenescence will aid the development of novel strategies to boost the immune system in older adults. In this review, we focus on major alterations of the immune system triggered by aging, and address the effect of chronic viral infections, effectiveness of vaccination of older adults and strategies to improve immune function in this vulnerable age group.

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.

The etiology of achalasia: An immune-dominant disease

There is accumulating evidence suggesting that an autoimmune component is involved in esophageal achalasia. An increase in immune cells, cytokines, chemokines, and autoimmune antibodies in serum and infiltration of immune cells in tissues support the view that immune-mediated inflammation is a crucial pathogenesis of inhibitory neuron degeneration in the lower esophageal sphincter. Infection of viruses such as the herpes virus family has been suspected of provoking the autoimmune reaction. Meanwhile, previous reports on immunogenetics have proposed that specific risk alleles on the human leukocyte antigen complex define the susceptible population to achalasia. In this study we reviewed current knowledge regarding the immune-related factors of achalasia, including immunology, viral infection and immunogenetic variations.

Aging and CMV discordance are associated with increased immune diversity between monozygotic twins

Background

Broadly, much of variance in immune system phenotype has been linked to the influence of non-heritable factors rather than genetics. In particular, two non-heritable factors: aging and human cytolomegavirus (CMV) infection, have been known to account for significant inter-individual immune variance. However, many specific relationships between them and immune composition remain unclear, especially between individuals over narrower age ranges. Further exploration of these relationships may be useful for informing personalized intervention development.

Results

To address this need, we evaluated 41 different cell type frequencies by mass cytometry and identified their relationships with aging and CMV seropositivity. Analyses were done using 60 healthy individuals, including 23 monozygotic twin pairs, categorized into young (12–31 years) and middle-aged (42–59 years). Aging and CMV discordance were associated with increased immune diversity between monozygotic twins overall, and particularly strongly in various T cell populations. Notably, we identified 17 and 11 cell subset frequencies as relatively influenced and uninfluenced by non-heritable factors, respectively, with results that largely matched those from studies on older-aged cohorts. Next, CD4+ T cell frequency was shown to diverge with age in twins, but with lower slope than in demographically similar non-twins, suggesting that much inter-individual variance in this cell type can be attributed to interactions between genetic and environmental factors. Several cell frequencies previously associated with memory inflation, such as CD27- CD8+ T cells and CD161+ CD4+ T cells, were positively correlated with CMV seropositivity, supporting findings that CMV infection may incur rapid aging of the immune system.

Conclusions

Our study confirms previous findings that aging, even within a relatively small age range and by mid-adulthood, and CMV seropositivity, both contribute significantly to inter-individual immune diversity. Notably, we identify several key immune cell subsets that vary considerably with aging, as well as others associated with memory inflation which correlate with CMV seropositivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12979-021-00216-1.

Immunity to acute virus infections with advanced age

New infections in general, and new viral infections amongst them, represent a serious challenge to an older organism. This review discusses the age-related alterations in responsiveness to infection from the standpoint of virus:host relationship and the host physiological whole-organism and specific immune response to the virus. Changes with age in the innate and adaptive immune system homeostasis and function are reviewed briefly. This is followed by a review of specific alterations and defects in the response of older organisms (chiefly mice and humans) to acute (particularly emerging and re-emerging) viral infections, with a very brief summary of the response to latent persistent infections. Finally, we provide a brief summary of the perspectives for possible interventions to enhance antiviral immunity.

Systematic analysis of infectious disease outcomes by age shows lowest severity in school-age children

The COVID-19 pandemic has ignited interest in age-specific manifestations of infection but surprisingly little is known about relative severity of infectious disease between the extremes of age. In a systematic analysis we identified 142 datasets with information on severity of disease by age for 32 different infectious diseases, 19 viral and 13 bacterial. For almost all infections, school-age children have the least severe disease, and severity starts to rise long before old age. Indeed, for many infections even young adults have more severe disease than children, and dengue was the only infection that was most severe in school-age children. Together with data on vaccine response in children and young adults, the findings suggest peak immune function is reached around 5-14 years of age. Relative immune senescence may begin much earlier than assumed, before accelerating in older age groups. This has major implications for understanding resilience to infection, optimal vaccine scheduling, and appropriate health protection policies across the life course.

Control of Immediate Early Gene Expression for Human Cytomegalovirus Reactivation

Human cytomegalovirus (HCMV) is a beta herpesvirus that persists for life in the majority of the world's population. The persistence of HCMV in the human population is due to the exquisite ability of herpesviruses to establish a latent infection that evades elimination by the host immune response. How the virus moves into and out of the latent state has been an intense area of research focus and debate. The prevailing paradigm is that the major immediate early promoter (MIEP), which drives robust expression of the major immediate early (MIE) transactivators, is epigenetically silenced during the establishment of latency, and must be reactivated for the virus to exit latency and re-enter productive replication. While it is clear that the MIEP is silenced by the association of repressive chromatin remodeling factors and histone marks, the mechanisms by which HCMV de-represses MIE gene expression for reactivation are less well understood. We have identified alternative promoter elements within the MIE locus that drive a second or delayed phase of MIE gene expression during productive infection. In the context of reactivation in THP-1 macrophages and primary CD34+ human progenitor cells, MIE transcripts are predominantly derived from initiation at these alternative promoters. Here we review the mechanisms by which alternative viral promoters might tailor the control of viral gene expression and the corresponding pattern of infection to specific cell types. Alternative promoter control of the HCMV MIE locus increases versatility in the system and allows the virus to tightly repress viral gene expression for latency but retain the ability to sense and respond to cell type-specific host cues for reactivation of replication.

Periodontal disease as a possible cause for Alzheimer's disease

Approximately 47 million people worldwide have been diagnosed with dementia, 60%-80% of whom have dementia of the Alzheimer's disease type. Unfortunately, there is no cure in sight. Defining modifiable risk factors for Alzheimer's disease may have a significant impact on its prevalence. An increasing body of evidence suggests that chronic inflammation and microbial dysbiosis are risk factors for Alzheimer's disease. Periodontal disease is a chronic inflammatory disease that develops in response to response to microbial dysbiosis. Many studies have shown an association between periodontal disease and Alzheimer's disease. The intent of this paper was to review the existing literature and determine, using the Bradford Hill criteria, whether periodontal disease is causally related to Alzheimer's disease.

Compatibility at amino acid position 98 of MICB reduces the incidence of graft-versus-host disease in conjunction with the CMV status

Graft-versus-host disease (GVHD) and cytomegalovirus (CMV)-related complications are leading causes of mortality after unrelated-donor hematopoietic cell transplantation (UD-HCT). The non-conventional MHC class I gene MICB, alike MICA, encodes a stress-induced polymorphic NKG2D ligand. However, unlike MICA, MICB interacts with the CMV-encoded UL16, which sequestrates MICB intracellularly, leading to immune evasion. Here, we retrospectively analyzed the impact of mismatches in MICB amino acid position 98 (MICB98), a key polymorphic residue involved in UL16 binding, in 943 UD-HCT pairs who were allele-matched at HLA-A, -B, -C, -DRB1, -DQB1 and MICA loci. HLA-DP typing was further available. MICB98 mismatches were significantly associated with an increased incidence of acute (grade II-IV: HR, 1.20; 95% CI, 1.15 to 1.24; P < 0.001; grade III-IV: HR, 2.28; 95% CI, 1.56 to 3.34; P < 0.001) and chronic GVHD (HR, 1.21; 95% CI, 1.10 to 1.33; P < 0.001). MICB98 matching significantly reduced the effect of CMV status on overall mortality from a hazard ratio of 1.77 to 1.16. MICB98 mismatches showed a GVHD-independent association with a higher incidence of CMV infection/reactivation (HR, 1.84; 95% CI, 1.34 to 2.51; P < 0.001). Hence selecting a MICB98-matched donor significantly reduces the GVHD incidence and lowers the impact of CMV status on overall survival.

Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity in patients with diabetes mellitus type 2 infected with Epstein-Barr virus

Oxidative stress is suggested to be the crucial factor in diabetes mellitus type 2 (DM2) pathogenesis and in the development of diabetic complications. Patients with DM2 may be more susceptible to infections due to hyperglycaemia-induced virulence of various microorganisms. Several studies pointed that Epstein-Barr virus (EBV) infection is associated with reactive oxygen species (ROS) production and/or activation of signalling pathways connected with ROS. The present study analyzed serum activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD) in DM2 patients with and without EBV infection. Blood and saliva were collected from 120 patients with DM2. EBV DNA was detected in the saliva using nested-PCR technique. Spectrophotometric methods were implemented to determine serum GPx and SOD activity with the use of diagnostic kits produced by Randox Laboratories. GPx and SOD activity was decreased in diabetic patients, with the lowest values in DM2 EBV-positive patients. There was correlation between GPx and SOD activity-with increased value of GPx, SOD activity was also rised. In patients with DM2 history longer than 10 years as well as in DM2 patients with obesity, antioxidant enzymes activity was decreased. Determination of examined parameters may be useful in diabetic patients with EBV infection and could be important prognostic factor.

Network topology dynamics of circulating biomarkers and cognitive performance in older Cytomegalovirus-seropositive or -seronegative men and women

Background

Cytokines are signaling molecules operating within complex cascade patterns and having exceptional modulatory functions. They impact various physiological processes such as neuroendocrine and metabolic interactions, neurotrophins’ metabolism, neuroplasticity, and may affect behavior and cognition. In our previous study, we found that sex and Cytomegalovirus (CMV)-serostatus may modulate levels of circulating pro- and anti-inflammatory cytokines, metabolic factors, immune cells, and cognitive performance, as well as associations between them.

Results

In the present study, we used a graph-theoretical approach to investigate the network topology dynamics of 22 circulating biomarkers and 11 measures of cognitive performance in 161 older participants recruited to undergo a six-months training intervention. For network construction, we applied coefficient of determination (R²) that was calculated for all possible pairs of variables (N = 33) in four groups (CMV⁻ men and women; CMV⁺ men and women). Network topology has been evaluated by clustering coefficient (CC) and characteristic path length (CPL) as well as local (E_local) and global (E_global) efficiency, showing the degree of network segregation (CC and E_local) and integration (CPL and E_global). We found that networks under consideration showed small-world networks properties with more random characteristics. Mean CC, as well as local and global efficiency were highest and CPL shortest in CMV⁻ males (having lowest inflammatory status and highest cognitive performance). CMV⁻ and CMV⁺ females did not show any significant differences. Modularity analyses showed that the networks exhibit in all cases highly differentiated modular organization (with Q-value ranged between 0.397 and 0.453).

Conclusions

In this work, we found that segregation and integration properties of the network were notably stronger in the group with balanced inflammatory status. We were also able to confirm our previous findings that CMV-infection and sex modulate multiple circulating biomarkers and cognitive performance and that balanced inflammatory and metabolic status in elderly contributes to better cognitive functioning. Thus, network analyses provide a useful strategy for visualization and quantitative description of multiple interactions between various circulating pro- and anti-inflammatory biomarkers, hormones, neurotrophic and metabolic factors, immune cells, and measures of cognitive performance and can be in general applied for analyzing interactions between different physiological systems.

The Unexplored World of Human Virome, Mycobiome, and Archaeome in Aging

In the last decades, improvements in different aspects of sanitation, medical care, and nutrition, among others, have permitted an increase in the average lifespan of human population around the world. These advances have stimulated an increased interest in the study of the aging process and age-sensitive characteristics, such as the microbial community that colonizes the human body (microbiome). The human microbiome is composed of bacteria (bacteriome), archaea (archaeome), fungi (mycobiome), and viruses (virome). To date, research has mainly been centered on the composition of the bacteriome, with other members remain poorly studied. Interestingly, changes in the composition of the microbiome have been implicated in aging and age-related diseases. Therefore, in the present perspective, we suggest expanding the scope to research to include the role and the possible associations that the other members of the microbiome could have in the aging organism. An expanded view of the microbiome would increase our knowledge of the physiology of aging and may be particularly valuable for the treatment and diagnosis of age-related diseases.

ZBTB32 restrains antibody responses to murine cytomegalovirus infections, but not other repetitive challenges

ZBTB32 is a transcription factor that is highly expressed by a subset of memory B cells and restrains the magnitude and duration of recall responses against hapten-protein conjugates. To define physiological contexts in which ZBTB32 acts, we assessed responses by Zbtb32^-/- mice or bone marrow chimeras against a panel of chronic and acute challenges. Mixed bone marrow chimeras were established in which all B cells were derived from either Zbtb32^-/- mice or control littermates. Chronic infection of Zbtb32^-/- chimeras with murine cytomegalovirus led to nearly 20-fold higher antigen-specific IgG2b levels relative to controls by week 9 post-infection, despite similar viral loads. In contrast, IgA responses and specificities in the intestine, where memory B cells are repeatedly stimulated by commensal bacteria, were similar between Zbtb32^-/- mice and control littermates. Finally, an infection and heterologous booster vaccination model revealed no role for ZBTB32 in restraining primary or recall antibody responses against influenza viruses. Thus, ZBTB32 does not limit recall responses to a number of physiological acute challenges, but does restrict antibody levels during chronic viral infections that periodically engage memory B cells. This restriction might selectively prevent recall responses against chronic infections from progressively overwhelming other antibody specificities.

Immunosenescence and Its Hallmarks: How to Oppose Aging Strategically? A Review of Potential Options for Therapeutic Intervention

Aging is accompanied by remodeling of the immune system. With time, this leads to a decline in immune efficacy, resulting in increased vulnerability to infectious diseases, diminished responses to vaccination, and a susceptibility to age-related inflammatory diseases. An age-associated immune alteration, extensively reported in previous studies, is the reduction in the number of peripheral blood naïve cells, with a relative increase in the frequency of memory cells. These two alterations, together with inflamm-aging, are considered the hallmarks of immunosenescence. Because aging is a plastic process, it is influenced by both nutritional and pharmacological interventions. Therefore, the role of nutrition and of immunomodulation in immunosenescence is discussed, due to the multifactorial influence on these hallmarks. The close connection between nutrition, intake of bioactive nutrients and supplements, immune function, and inflammation demonstrate the key role of dietary strategies as regulators of immune response and inflammatory status, hence as possible modulators of the rate of immunosenescence. In addition, potential options for therapeutic intervention are clarified. In particular, the use of interleukin-7 as growth factor for naïve T cells, the function of checkpoint inhibitors in improving T cell responses during aging and, the potential of drugs that inhibit mitogen-activated protein kinases and their interaction with nutrient signaling pathways are discussed. Finally, it is suggested that the inclusion of appropriate combinations of toll-like receptor agonists may enhance the efficacy of vaccination in older adults.

Prevalence of Epstein-Barr virus, human papillomavirus, cytomegalovirus and herpes simplex virus type 1 in patients with diabetes mellitus type 2 in south-eastern Poland

A microbiota is a complex ecosystem of microorganisms consisting of bacteria, viruses, protozoa, and fungi living in different niches of the human body, which plays an essential role in many metabolic functions. Modifications in the microbiota composition can lead to several diseases, including metabolic disorders. The aim of this study was to analyze the prevalence of four viruses which can cause persistent infections-Epstein-Barr virus (EBV), human papillomavirus (HPV), cytomegalovirus (CMV), and herpes simplex virus type 1 (HSV-1) in patients with diabetes mellitus type 2 (DM2). Blood, saliva and oral swabs were collected from all the study participants. The nested-PCR technique was used to detect the viral DNA. DNA of at least one virus was detected in 71.1% of diabetic patients and in 30% of individuals without diabetes. In patients with diabetes EBV DNA was detected the most frequently (25.4%), followed by HPV- 19.1%, HSV- 10.4% and CMV- 5.2%. A higher percentage of EBV+HPV co-infection was found among men (30.8%). EBV DNA was statistically more often detected in patients living in rural areas (53.7%), while HPV (91.5%) and EBV+HPV co-infection (22.2%) prevailed among patients from urban areas. In patients with a DM2 history longer than 10 years viral infection was detected more frequently. The prevalence of EBV, HPV and the EBV+HPV co-infection was significantly higher in diabetic patients than in individuals without diabetes. The frequency of these infections depended on the duration of the disease (DM2).

A longitudinal study of the stability, variability, and interdependencies among late-differentiated T and NK cell subsets in older adults

The stability and variability of older adults' late-differentiated peripheral blood T and natural killer (NK) cells over time remains incompletely quantified or understood. We examined the variability and change over time in T and NK cell subsets in a longitudinal sample of older adults; the effects of sex, cytomegalovirus (CMV) serostatus, and chronic disease severity on immune levels and trajectories; and interdependencies among T and NK cell subsets. Older adults (N = 149, age 64-94 years, 42% male) provided blood every 6 months for 2.5 years (up to 5 waves) to evaluate late-differentiated CD8 T cells (CD28-, CD57+) and CD56dimNK cells (CD57+, NKG2C+, FcɛRIγ-). In multilevel models, most of the variance in immune subsets reflected stable differences between people. However, CD56dimNK cell subsets (CD57+ and FcɛRIγ-) also increased with age, whereas T cell subsets did not. Independent of age, all subsets examined were higher in CMV-positive older adults. Men had higher levels of CD56dim CD57+ than women. Chronic disease was not associated with any immune subset investigated. T and NK cell subsets correlated within each cell type, but interdependencies differed by CMV serostatus. Our results suggest the accumulation of these stable cell populations may be driven less by chronological aging, even less by chronic disease severity, and more by CMV, which may differentially skew T and NK cell differentiation.

Viruses and immunosenescence - more players in the game

Viral infections are common clinical problems in aged individuals often affecting both mortality and morbidity. The pathogenic mechanisms of the various viruses are not universal in aged individuals, i.e. the clinical disease may be caused by the reactivation of a virus which has stayed in the body in a latent form, or alternatively, the virus is exogenous, derived from the environment. However, it is now evident, that this concept is too simple. Recent data have shown that in our body, even in the blood of healthy individuals, there are large amount of various viruses, which seem to live in balance with our immune defense mechanism (viral normal flora?). Moreover, there is now data suggesting that remnants of ancient retroviral infections in our genome can be activated and show virus-like activities. The possible significance of these findings in immunosenescence is discussed.

The Immune System and Its Dysregulation with Aging

Aging leads to numerous changes that affect all physiological systems of the body including the immune system, causing greater susceptibility to infectious disease and contributing to the cardiovascular, metabolic, autoimmune, and neurodegenerative diseases of aging. The immune system is itself also influenced by age-associated changes occurring in such physiological systems as the endocrine, nervous, digestive, cardio-vascular and muscle-skeletal systems. This chapter describes the multidimensional effects of aging on the most important components of the immune system. It considers the age-related changes in immune cells and molecules of innate and adaptive immunity and consequent impairments in their ability to communicate with each other and with their aged environment. The contribution of age-related dysregulation of hematopoiesis, required for continuous replenishment of immune cells throughout life, is discussed in this context, as is the developmentally-programmed phenomenon of thymic involution that limits the output of naïve T cells and markedly contributes to differences between younger and older people in the distribution of peripheral blood T-cell types. How all these changes may contribute to low-grade inflammation, sometimes dubbed "inflammaging", is considered. Due to findings implicating elevated inflammatory immuno-mediators in age-associated chronic autoimmune and neurodegenerative processes, evidence for their possible contribution to neuroinflammation is reviewed.

Cytomegalovirus memory inflation and immune protection

Cytomegalovirus (CMV) infection induces powerful and sustained T-cell responses against a few selected immunodominant antigenic epitopes. This immune response was named memory inflation, because it does not contract in the long term, and may even expand over months and years of virus latency. It is by now understood that memory inflation does not occur at the expense of the naïve T-cell pool, but rather as a competitive selection process within the effector pool, where viral antigens with higher avidity of TCR binding and with earlier expression patterns outcompete those that are expressed later and bind TCRs less efficiently. It is also understood that inflationary epitopes require processing by the constitutive proteasome in non-hematopoietic cells, and this likely implies that memory inflation is fuelled by direct low-level antigenic expression in latently infected cells. This review proposes that these conditions make inflationary epitopes the optimal candidates for adoptive immunotherapy of CMV disease in the immunocompromised host. At present, functional target CMV epitopes have been defined only for the most common HLA haplotypes. Mapping the uncharacterized inflationary epitopes in less frequent HLAs may, thus, be a strategy for the identification of optimal immunotherapeutic targets in patients with uncommon haplotypes.

Cytomegalovirus: Shape-Shifting the Immune System

Systems-based based approaches have begun to shed light on extrinsic factors that contribute to immune system variation. Among these, CMV (HHV-5, a β-herpesvirus) imposes a surprisingly profound impact. Most of the world's population is CMV⁺, and the virus goes through three distinct infection phases en route to establishing lifelong détente with its host. Immune control of CMV in each phase recruits unique arms of host defense, and in turn the virus employs multiple immune-modulatory strategies that help facilitate the establishment of lifelong persistence. In this review, we explain how CMV shapes immunity and discuss the impact it may have on overall health.

Do cytomegalovirus-specific memory T cells interfere with new immune responses in lymphoid tissues?

In both mice and humans, the CD8 T cell compartment is expanded with age in the presence of a cytomegalovirus (CMV) infection due to an absolute increase in the CD8+ T cell effector memory (TEM) cells. It has been hypothesized that in CMV+ subjects, such accumulated TEM cells could interfere with responses to new infection by competing for space/resources or could inhibit new responses by other, undefined, means. Here we present evidence against this hypothesis. We show that MCMV-specific CD8 T cells accumulate in blood and bone marrow, but not lymph nodes (frequent sites of immune response initiation), in either persistent lifelong CMV infection or following reactivation. Moreover, adoptive transfer of effector memory T cells from MCMV positive mice into naïve animals did not interfere with either humoral or cellular response to West Nile virus or Listeria monocytogenes infection in recipient mice. We conclude that MCMV infection is unlikely to inhibit new immune responses in old animals through direct interference of MCMV-specific CD8 T cells with the priming.

The Modulatory Effect of Gender and Cytomegalovirus-Seropositivity on Circulating Inflammatory Factors and Cognitive Performance in Elderly Individuals

Aging is characterized by a chronic increase in the systemic levels of inflammatory cytokines even in ostensibly healthy individuals. The drivers of age-related increase in systemic inflammation are unclear but one potential contributor may be a persistent infection with Cytomegalovirus (CMV). In this study, we characterized the inflammatory status of 161 older participants recruited to undergo a six-month training intervention. We investigated the influence of gender and CMV-seropositivity on the main inflammatory and anti-inflammatory circulating biomarkers, such as cytokines, receptor antagonist, soluble receptor, immune cells, and relevant metabolic markers. We found that both gender and CMV-seropositivity modulate circulating peripheral biomarkers, and that CMV-infection modifies associations among the latter. Moreover, we observed an interaction between CMV-serostatus and gender associations with cognitive abilities: gender differences in fluid intelligence (Gf) and working memory (WM) were noted only in CMV-negative individuals. Finally, we found that in the CMV-seronegative participants Gf, episodic memory (EM), and WM correlated negatively with pro-inflammatory tumor necrosis factor (TNF); and EM correlated positively with anti-inflammatory interleukin (IL)-10. In CMV-seropositive individuals EM and Gf correlated negatively with pro-inflammatory IL-6, while EM, Gf, and WM correlated negatively with anti-inflammatory IL-1RA. We conclude that both CMV-serostatus and gender may modulate neuroimmune factors, cognitive performance and the relationship between the two domains and should therefore be considered in comparative and interventional studies with elderly people.

The Human Gut Virome in Hypertension

Objectives: Previous studies have reported that the gut microbiome has an important link with the development of hypertension. Though previous researches have focused on the links of gut bacteria with hypertension, little has been known about the linkage of gut viruses to hypertension and the development of hypertension, largely due to the lack of data mining tools for such investigation. In this work, we have analyzed 196 fecal metagenomic data related to hypertension aiming to profile the gut virome and link the gut virome to pre-hypertension and hypertension. Design: Here, we have applied a statistically sound method for mining of gut virome data and linking gut virome to hypertension. We characterized the viral composition and bacterial composition of 196 samples, identified the viral-type of each sample and linked gut virome to hypertension. Results: We stratified these 196 fecal samples into two viral-types and selected 32 viruses as the biomarkers for these groups. We found that viruses could have a superior resolution and discrimination power than bacteria for differentiation of healthy samples and pre-hypertension samples, as well as hypertension samples. Moreover, as to the co-occurrence networks linking viruses and bacteria, we found increasingly pervasive virus-bacteria linkages from healthy people to pre-hypertension people to hypertension patients. Conclusion: Overall, our results have shown ample indications of the link between human gut virome and hypertension, and could help provide microbial solutions toward early diagnoses of hypertension.

Human thymopoiesis is influenced by a common genetic variant within the TCRA-TCRD locus

The thymus is the primary lymphoid organ where naïve T cells are generated; however, with the exception of age, the parameters that govern its function in healthy humans remain unknown. We characterized the variability of thymic function among 1000 age- and sex-stratified healthy adults of the Milieu Intérieur cohort, using quantification of T cell receptor excision circles (TRECs) in peripheral blood T cells as a surrogate marker of thymopoiesis. Age and sex were the only nonheritable factors identified that affect thymic function. TREC amounts decreased with age and were higher in women compared to men. In addition, a genome-wide association study revealed a common variant (rs2204985) within the T cell receptor TCRA-TCRD locus, between the DD2 and DD3 gene segments, which associated with TREC amounts. Strikingly, transplantation of human hematopoietic stem cells with the rs2204985 GG genotype into immunodeficient mice led to thymopoiesis with higher TRECs, increased thymocyte counts, and a higher TCR repertoire diversity. Our population immunology approach revealed a genetic locus that influences thymopoiesis in healthy adults, with potentially broad implications in precision medicine.

Drawing on disorder: How viruses use histone mimicry to their advantage

Humans carry trillions of viruses that thrive because of their ability to exploit the host. In this exploitation, viruses promote their own replication by suppressing the host antiviral response and by inducing changes in host biosynthetic processes, often with extremely small genomes of their own. In the review, we discuss the phenomenon of histone mimicry by viral proteins and how this mimicry allows the virus to dial in to the cell's transcriptional processes and establish a cell state that promotes infection. We suggest that histone mimicry is part of a broader viral strategy to use intrinsic protein disorder as a means to overcome the size limitations of its own genome and to maximize its impact on host protein networks. In particular, we discuss how intrinsic protein disorder may enable viral proteins to interfere with phase-separated host protein condensates, including those that contribute to chromatin-mediated control of gene expression.

Lifelong CMV infection improves immune defense in old mice by broadening the mobilized TCR repertoire against third-party infection

Lifelong interactions between host and the ubiquitous and persistent cytomegalovirus (CMV) have been proposed to contribute to the age-related decline in immunity. Prior work from us and others found some support for that idea, yet evidence that this led to increased vulnerability to other infections was not obtained. Moreover, evidence has accumulated that CMV infection can be beneficial to immune defense in young/adult mice and humans, dominantly via enhanced innate immunity. Here, we describe an unexpected impact of murine CMV (MCMV) upon the T cell response of old mice to Listeria monocytogenes expressing the model antigen, OVA (Lm-OVA). Single-cell sequencing of the OVA-specific CD8 T cell receptor β (TCRβ) repertoire of old mice demonstrated that old MCMV-infected mice recruited many diverse clonotypes that afforded broad and often more efficient recognition of antigenic peptide variants. This stood in contrast to old control mice, which exhibited strong narrowing and homogenization of the elicited repertoire. High-throughput sequencing of the total naïve CD8 TCRβ repertoire showed that many of these diverse OVA-specific clonotypes were present in the naïve CD8 repertoire of mice in all groups (adult, old control, and old MCMV⁺) yet were only recruited into the Lm-OVA response in MCMV⁺ old mice. These results have profound implications for our understanding of T cell immunity over a life span and suggest that our coevolution with CMV may include surprising, potentially positive impacts on adaptive heterologous immunity in late life.