Impact of Persistent Cytomegalovirus Infection on Dynamic Changes in Human Immune System Profile

Potential relationship between cytomegalovirus and immunosenescence: Evidence from observational studies

Immunosenescence (IS) occurs as a natural outcome of ageing and may be described as a decline in immune system flexibility and adaptability to sufficiently respond to new, foreign antigens. Potential factors that may precipitate IS include persistent herpesvirus infections, such as cytomegalovirus (CMV). Here, we conducted a review of the literature evaluating the potential association between CMV and IS. Twenty-seven epidemiologic studies that included direct comparisons between CMV-seropositive and CMV-seronegative immunocompetent individuals were analysed. The majority of these studies (n = 20) were conducted in European populations. The strength of evidence supporting a relationship between CMV, and various IS-associated immunologic endpoints was assessed. T-cell population restructuring was the most prominently studied endpoint, described in 21 studies, most of which reported a relationship between CMV and reduced CD4:CD8 T-cell ratio or modified CD8+ T-cell levels. Telomere length (n = 4) and inflammageing (n = 3) were less frequently described in the primary literature, and the association of these endpoints with CMV and IS was less pronounced. An emergent trend from our review is the potential effect modification of the CMV-IS relationship with both sex and age, indicating the importance of considering various effector variables when evaluating associations between CMV and IS. Our analysis revealed plausible mechanisms that may underlie the larger epidemiologic trends seen in the literature that support the indirect effect of CMV on IS. Future studies are needed to clarify CMV-associated and IS-associated immunologic endpoints, as well as in more diverse global and immunocompromised populations.

Development of a highly cytotoxic, clinical-grade virus-specific T cell product for adoptive T cell therapy

At present, recipients of allogeneic hematopoietic stem-cells are still suffering from recurrent infections after transplantation. Infusion of virus-specific T cells (VST) post-transplant reportedly fights several viruses without increasing the risk of de novo graft-versus-host disease. This study targeted cytomegalovirus (CMV) for the development of an innovative approach for generating a very specific VST product following Good Manufacturing Practices (GMP) guidelines. We used a sterile disposable compartment named the Leukoreduction System Chamber (LRS-chamber) from the apheresis platelet donation kit as the starting material, which has demonstrated high levels of T cells. Using a combination of IL-2 and IL-7 we could improve expansion of CMV-specific T cells. Moreover, by developing and establishing a new product protocol, we were able to stimulate VST proliferation and favors T cell effector memory profile. The expanded VST were enriched in a closed automated system, creating a highly pure anti-CMV product, which was pre-clinically tested for specificity in vitro and for persistence, biodistribution, and toxicity in vivo using NOD scid mice. Our results demonstrated very specific VST, able to secrete high amounts of interferon only in the presence of cells infected by the human CMV strain (AD169), and innocuous to cells partially HLA compatible without viral infection.

Current Knowledge on the Interaction of Human Cytomegalovirus Infection, Encoded miRNAs, and Acute Aortic Syndrome

Aortic dissection is a clinicopathological entity caused by rupture of the intima, leading to a high mortality if not treated. Over time, diagnostic and investigative methods, antihypertensive therapy, and early referrals have resulted in improved outcomes according to registry data. Some data have also emerged from recent studies suggesting a link between Human Cytomegalovirus (HCMV) infection and aortic dissection. Furthermore, the use of microRNAs has also become increasingly widespread in the literature. These have been noted to play a role in aortic dissections with elevated levels noted in studies as early as 2017. This review aims to provide a broad and holistic overview of the role of miRNAs, while studying the role of HCMV infection in the context of aortic dissections. The roles of long non-coding RNAs, circular RNAs, and microRNAs are explored to identify changes in expression during aortic dissections. The use of such biomarkers may one day be translated into clinical practice to allow early detection and prognostication of outcomes and drive preventative and therapeutic options in the future.

Associations between human cytomegalovirus infection and type 2 diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

Multiple studies have reported a potential contribution of human cytomegalovirus (HCMV) to the pathogenesis of type 1 diabetes and post-transplantation diabetes. However, the association between HCMV and type 2 diabetes mellitus (T2DM) remains unclear. In this paper, we employ the meta-analysis approach to investigate the potential correlation between HCMV infection and T2DM.

METHOD

The data of our study were collected from PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure and WAN FANG databases from inception to November 2022. Using the Review Manager V.5.4 software, the meta-analysis was performed.

RESULTS

A total of 18 139 patients from 22 studies were included in our analysis. In the Asian subgroup, the patients with T2DM group had a significantly higher frequency of HCMV infection and older age compared with the healthy group. In the European, the frequency of HCMV infection in the T2DM was lower than the healthy group, although this difference was not statistically significant. After adjusting for demographic factors, the adjusted OR of T2DM for risk of by HCMV status was not found to be significant (adjusted OR=1.19, 95% CI=0.88 to 1.62, p>0.05). Additionally, T2DM with vasculopathy had a significantly higher rate of HCMV infection compared with those without vasculopathy (OR=1.87, 95% CI=1.24 to 2.83, p<0.05). Among T2DM with HCMV infection, there were significant increases in fasting blood glucose levels and the proportion of CD8+ T lymphocytes. Conversely, fasting blood insulin levels, the proportion of CD4+ T lymphocyte and the CD4+/CD8+ ratio were significantly decreased compared with the healthy group.

CONCLUSION

At present, the available evidence does not provide a clear understanding of whether there is a significant association between T2DM and HCMV infection. Additionally, T2DM with HCMV infection exhibited significantly worse blood glucose regulation and immune markers, as well as a higher frequency of vasculopathy.

PROSPERO REGISTRATION NUMBER

CRD42022342066.

Immune-checkpoint expression in antigen-presenting cells (APCs) of cytomegaloviruses infection after transplantation: as a diagnostic biomarker

Cytomegalovirus (CMV), a member of the Herpesviridae family, mostly causes only slight feverish symptoms or can be asymptomatic in immunocompetent individuals. However, it is known to be particularly a significant cause of morbidity in immunocompromised patients, including transplant recipients, whose immune system has been weakened due to the consumption of immunosuppressor drugs. Therefore, the diagnosis of CMV infection after transplantation is crucial. New diagnostic methods for the quick detection of CMV have been developed as a result of understanding the clinical importance of invasive CMV. Antigen-presenting cells (APCs) and T cells are important components of the immune system and it may be possible to diagnose viral infections using immunological markers, such as lymphocytosis, cytotoxic T lymphocytes (CTL), and serum cytokine levels. Moreover, PD-1, CTLA 4, and TIGIT, which are expressed on certain T cells and antigen-presenting cells, are over-expressed during the infection. The assessment of CMV infection based on T cell and APC activity, and the expression of immunological checkpoints, can be helpful for the diagnosis of transplant patients at risk for CMV infection. In this review, we will investigate how immune checkpoints affect immune cells and how they impair organ transplantation after CMV infection.

The association of human cytomegalovirus with biomarkers of inflammation and immune activation in breast cancer

BACKGROUND

The presence of human cytomegalovirus (HCMV) in breast cancer has been reported, suggesting a potential association between HCMV infection and breast carcinogenesis.

OBJECTIVE

To evaluate the association between HCMV infection and immune activation and inflammatory markers in breast cancer.

METHODS

HCMV DNA was detected from all patients using real-time PCR, Anti HCMV IgM and IgG antibodies were measured. IL-17 and IL-22 concentrations were detected by ELISA. Assessment of NLR and PLR was done, and cell proliferation was assessed using MTT assay.

RESULTS

The results revealed a significantly increased prevalence of anti-HCMV IgG and HCMV DNA in patients compared to both benign and control groups where positive HCMV prevalence was significantly associated with vascular invasion, proliferation rate, high neutrophil-to-lymphocyte ratio (NLR), and elevated IL-17 serum level. Furthermore, we demonstrated that increased serum IL-17 in patients was markedly associated with tumor stage, vascular invasion, and high NLR.

CONCLUSION

It can be concluded that HCMV infection may have vital roles in breast cancer pathogenesis. Moreover, altered peripheral blood cells and cytokines may result in disordered immune response in breast cancer patients.

Quantification of T-cell dynamics during latent cytomegalovirus infection in humans

Cytomegalovirus (CMV) infection has a major impact on the T-cell pool, which is thought to be associated with ageing of the immune system. The effect on the T-cell pool has been interpreted as an effect of CMV on non-CMV specific T-cells. However, it remains unclear whether the effect of CMV could simply be explained by the presence of large, immunodominant, CMV-specific memory CD8+ T-cell populations. These have been suggested to establish through gradual accumulation of long-lived cells. However, little is known about their maintenance. We investigated the effect of CMV infection on T-cell dynamics in healthy older adults, and aimed to unravel the mechanisms of maintenance of large numbers of CMV-specific CD8+ T-cells. We studied the expression of senescence, proliferation, and apoptosis markers and quantified the in vivo dynamics of CMV-specific and other memory T-cell populations using in vivo deuterium labelling. Increased expression of late-stage differentiation markers by CD8+ T-cells of CMV+ versus CMV- individuals was not solely explained by the presence of large, immunodominant CMV-specific CD8+ T-cell populations. The lifespans of circulating CMV-specific CD8+ T-cells did not differ significantly from those of bulk memory CD8+ T-cells, and the lifespans of bulk memory CD8+ T-cells did not differ significantly between CMV- and CMV+ individuals. Memory CD4+ T-cells of CMV+ individuals showed increased expression of late-stage differentiation markers and decreased Ki-67 expression. Overall, the expression of senescence markers on T-cell populations correlated positively with their expected in vivo lifespan. Together, this work suggests that i) large, immunodominant CMV-specific CD8+ T-cell populations do not explain the phenotypical differences between CMV+ and CMV- individuals, ii) CMV infection hardly affects the dynamics of the T-cell pool, and iii) large numbers of CMV-specific CD8+ T-cells are not due to longer lifespans of these cells.

Don't Go Breaking My Heart: MCMV as a Model for HCMV-Associated Cardiovascular Diseases

Human Cytomegalovirus (HCMV) is a widespread pathogen that causes lifelong latent infection and is associated with the exacerbation of chronic inflammatory diseases in seropositive individuals. Of particular impact, HCMV infection is known to worsen many cardiovascular diseases including myocarditis, atherosclerosis, hypertension, and transplant vasculopathy. Due to its similarity to HCMV, murine CMV (MCMV) is an appropriate model to understand HCMV-induced pathogenesis in the heart and vasculature. MCMV shares similar sequence homology and recapitulates much of the HCMV pathogenesis, including HCMV-induced cardiovascular diseases. This review provides insight into HCMV-associated cardiovascular diseases and the murine model of MCMV infection, which has been used to study the viral pathogenesis and mechanisms contributing to cardiovascular diseases. Our new functional studies using echocardiography demonstrate tachycardia and hypertrophy in the mouse, similar to HCMV-induced myocarditis in humans. For the first time, we show long term heart dysfunction and that MCMV reactivates from latency in the heart, which raises the intriguing idea that HCMV latency and frequent virus reactivation perturbs long term cardiovascular function.

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

Objectives

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

Methods

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

Results

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

Conclusion

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

Vaccine Vectors Harnessing the Power of Cytomegaloviruses

Cytomegalovirus (CMV) species have been gaining attention as experimental vaccine vectors inducing cellular immune responses of unparalleled strength and protection. This review outline the strengths and the restrictions of CMV-based vectors, in light of the known aspects of CMV infection, pathogenicity and immunity. We discuss aspects to be considered when optimizing CMV based vaccines, including the innate immune response, the adaptive humoral immunity and the T-cell responses. We also discuss the antigenic epitopes presented by unconventional major histocompatibility complex (MHC) molecules in some CMV delivery systems and considerations about routes for delivery for the induction of systemic or mucosal immune responses. With the first clinical trials initiating, CMV-based vaccine vectors are entering a mature phase of development. This impetus needs to be maintained by scientific advances that feed the progress of this technological platform.

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.

Generation, maintenance and tissue distribution of T cell responses to human cytomegalovirus in lytic and latent infection

Understanding how the T cell memory response directed towards human cytomegalovirus (HCMV) develops and changes over time while the virus persists is important. Whilst HCMV primary infection and periodic reactivation is well controlled by T cell responses in healthy people, when the immune system is compromised such as post-transplantation, during pregnancy, or underdeveloped such as in new-born infants and children, CMV disease can be a significant problem. In older people, HCMV infection is associated with increased risk of mortality and despite overt disease rarely being seen there are increases in HCMV-DNA in urine of older people suggesting that there is a change in the efficacy of the T cell response following lifelong infection. Therefore, understanding whether phenomenon such as “memory inflation” of the immune response is occurring in humans and if this is detrimental to the overall health of individuals would enable the development of appropriate treatment strategies for the future. In this review, we present the evidence available from human studies regarding the development and maintenance of memory CD8 + and CD4 + T cell responses to HCMV. We conclude that there is only limited evidence supportive of “memory inflation” occurring in humans and that future studies need to investigate immune cells from a broad range of human tissue sites to fully understand the nature of HCMV T cell memory responses to lytic and latent infection.

The impact of inflationary cytomegalovirus-specific memory T cells on anti-tumour immune responses in patients with cancer

Human cytomegalovirus (CMV) is a ubiquitous, persistent beta herpesvirus. CMV infection contributes to the accumulation of functional antigen-specific CD8⁺ T-cell pools with an effector-memory phenotype and enrichment of these immune cells in peripheral organs. We review here this 'memory T-cell inflation' phenomenon and associated factors including age and sex. 'Collateral damage' due to CMV-directed immune reactivity may occur in later stages of life - arising from CMV-specific immune responses that were beneficial in earlier life. CMV may be considered an age-dependent immunomodulator and a double-edged sword in editing anti-tumour immune responses. Emerging evidence suggests that CMV is highly prevalent in patients with a variety of cancers, particularly glioblastoma. A better understanding of CMV-associated immune responses and its implications for immune senescence, especially in patients with cancer, may aid in the design of more clinically relevant and tailored, personalized treatment regimens. 'Memory T-cell inflation' could be applied in vaccine development strategies to enrich for immune reactivity where long-term immunological memory is needed, e.g. in long-term immune memory formation directed against transformed cells.

Impact of age and cytomegalovirus on CD8+ T-cell compartment remodeling after solid organ transplantation: A one-year follow-up study

Cytomegalovirus (CMV), a member of the β-herpesvirus family, is a major complicating infection in transplant patients. CMV latency has a long-term impact on CD8⁺ T-cell differentiation. It is unclear, however, whether this effect can be detected in one-year period. To investigate this, we analyzed the remodeling of the CD8⁺ T-cell compartment during the first year after solid organ transplantation. A total of 55 kidney or lung transplant patients were recruited. CD8⁺ T-cell subsets were prospectively analyzed at pretransplant, at 3 or 6months and 12months after transplantation (mo post-Tx). A significant increase in the frequency of CD27^-CD28^-CD8⁺ T cells (from 32.8% to 42.3%; p=0.014) was observed from pretransplant to 12mo post-Tx. Further analysis, however, showed that the largest expansion was observed from 3/6 to 12mo post-Tx whereas small non-significant variations were observed from pretransplant to 3/6mo post-Tx. The adjusted analysis showed that age and CMV seropositivity were statistically associated with the baseline frequency of CD27^-CD28^-CD8⁺ T cells. Additionally, CMV replication was related to the posttransplant expansion of this subpopulation, since it was not observed in patients without CMV viremia (24% vs. 4.2%). The results indicate that the expanded frequency associated with late CMV replication is additive to the baseline frequency related to aging and CMV seropositivity. If the expanded frequency remains at this high level for a long period it might have clinical consequences related to the control of future reactivations of CMV or of other related viruses.