Human immunoglobulin G levels of viruses and associated glioma risk

Time trends in herpesvirus seroepidemiology among Swedish adults

BACKGROUND

Human herpesviruses are widespread among the human population. The infections often occur unnoticed, but severe disease as well as long-term sequelae are part of the symptom spectrum. The prevalence varies among subpopulations and with time. The aim of this study was to describe the seroprevalence of Immunoglobulin G against Herpes simplex 1, Herpes simplex 2, Epstein-Barr virus and Cytomegalovirus in the adult Swedish population over a time period of several decades.

METHODS

Serum samples (n = 892) from biobanks, originating from 30-year-old women, 50-year-old men and 50-year-old women sampled between 1975 and 2018, were analyzed for presence of anti-herpesvirus antibodies. Linear regression analysis was used to test for a correlation between birth year and seroprevalence. Multiple linear regression analysis was used to differentiate between other factors such as age and gender.

RESULTS

Birth year correlated negatively with the prevalence of immunoglobulin G against Herpes simplex 1 and Epstein-Barr virus (p = 0.004 and 0.033), and positively with Immunoglobulin G against Cytomegalovirus (p = 0.039). When participant categories were analyzed separately, birth year correlated negatively with the prevalence of Immunoglobulin G against Herpes simplex 1 and Herpes simplex 2 (p = 0.032 and 0.028) in 30-year-old women, and with the prevalence of Immunoglobulin G against Cytomegalovirus in 50-year-old men (p = 0.011).

CONCLUSIONS

The prevalence of Immunoglobulin G against Herpes simplex 1, Herpes simplex 2 and Epstein-Barr virus decreases in later birth cohorts. This indicates a trend of declining risk of getting infected with these viruses as a child and adolescent.

Association between viral infections and glioma risk: a two-sample bidirectional Mendelian randomization analysis

BACKGROUND

Glioma is one of the leading types of brain tumor, but few etiologic factors of primary glioma have been identified. Previous observational research has shown an association between viral infection and glioma risk. In this study, we used Mendelian randomization (MR) analysis to explore the direction and magnitude of the causal relationship between viral infection and glioma.

METHODS

We conducted a two-sample bidirectional MR analysis using genome-wide association study (GWAS) data. Summary statistics data of glioma were collected from the largest meta-analysis GWAS, involving 12,488 cases and 18,169 controls. Single-nucleotide polymorphisms (SNPs) associated with exposures were used as instrumental variables to estimate the causal relationship between glioma and twelve types of viral infections from corresponding GWAS data. In addition, sensitivity analyses were performed.

RESULTS

After correcting for multiple tests and sensitivity analysis, we detected that genetically predicted herpes zoster (caused by Varicella zoster virus (VZV) infection) significantly decreased risk of low-grade glioma (LGG) development (OR = 0.85, 95% CI: 0.76-0.96, P = 0.01, FDR = 0.04). No causal effects of the other eleven viral infections on glioma and reverse causality were detected.

CONCLUSIONS

This is one of the first and largest studies in this field. We show robust evidence supporting that genetically predicted herpes zoster caused by VZV infection reduces risk of LGG. The findings of our research advance understanding of the etiology of glioma.

Higher Human Cytomegalovirus (HCMV) Specific IgG Antibody Levels in Plasma Samples from Patients with Metastatic Brain Tumors Are Associated with Longer Survival

Background: Human cytomegalovirus (HCMV) has been detected in tissue samples from patients with glioblastoma but little is known about the systemic immunological response to HCMV in these patients. Objectives: To investigate the presence and clinical significance of HCMV antibodies levels in plasma samples obtained from patients with brain tumors. Materials and Methods: HCMV-specific IgG and IgM antibody levels were determined in 59 plasma samples collected from brain tumor patients included in a prospective study and in 114 healthy individuals. We examined if the levels of HCMV specific antibodies varied in patients with different brain tumor diagnoses compared to healthy individuals, and if antibody levels were predictive for survival time. Results: HCMV specific IgG antibodies were detected by ELISA in 80% and 89% of patients with GBM and astrocytoma grades II-III, respectively, in all samples (100%) from patients with secondary GBM and brain metastases, as well as in 80% of healthy donors (n = 114). All plasma samples were negative for HCMV-IgM. Patients with brain metastases who had higher plasma HCMV-IgG titers had longer survival times (p = 0.03). Conclusions: HCMV specific IgG titers were higher among all brain tumor patient groups compared with healthy donors, except for patients with secondary GBM. Higher HCMV specific IgG levels in patients with brain metastases but not in patients with primary brain tumors were associated with prolonged survival time.

Longitudinal Effects of Herpesviruses on Multiple Cognitive Outcomes in Healthy Elderly Adults

BACKGROUND

Herpesviruses have been proposed to be involved in Alzheimer's disease development as potentially modifiable pathology triggers.

OBJECTIVE

To investigate associations of serum antibodies for herpes simplex virus (HSV)-1 and cytomegalovirus (CMV) and anti-herpesvirus treatment with cognitive outcomes in relation to interactions with APOE ɛ4.

METHODS

The study included 849 participants in the population-based Prospective Investigation of the Vasculature in Uppsala Seniors study. Cognitive performance at the ages of 75 and 80 years was assessed using the Mini-Mental State Examination (MMSE), trail-making test (TMT) A and B, and 7-minute screening test (7MS).

RESULTS

Anti- HSV-1 IgG positivity was associated cross-sectionally with worse performance on the MMSE, TMT-A, TMT-B, 7MS, enhanced free recall, and verbal fluency tests (p = 0.016, p = 0.016, p <  0.001, p = 0.001, p = 0.033, and p <  0.001, respectively), but not orientation or clock drawing. Cognitive scores did not decline over time and longitudinal changes did not differ according to HSV-1 positivity. Anti- CMV IgG positivity was not associated cross-sectionally with cognition, but TMT-B scores declined more in anti- CMV IgG carriers. Anti- HSV-1 IgG interacted with APOE ɛ4 in association with worse TMT-A and better enhanced cued recall. Anti- HSV IgM interacted with APOE ɛ4 and anti-herpesvirus treatment in association with worse TMT-A and clock drawing, respectively.

CONCLUSION

These findings indicate that HSV-1 is linked to poorer cognition in cognitively healthy elderly adults, including impairments in executive function, memory, and expressive language. Cognitive performance did not decline over time, nor was longitudinal decline associated with HSV-1.

Pre-diagnostic blood biomarkers for adult glioma

Glioma is one of the most common malignant primary brain tumours in adults, of which, glioblastoma is the most prevalent and malignant entity. Glioma is often diagnosed at a later stage of disease progression, which means it is associated with significant mortality and morbidity. Therefore, there is a need for earlier diagnosis of these tumours, which would require sensitive and specific biomarkers. These biomarkers could better predict glioma onset to improve diagnosis and therapeutic options for patients. While liquid biopsies could provide a cheap and non-invasive test to improve the earlier detection of glioma, there is little known on pre-diagnostic biomarkers which predate disease detection. In this review, we examine the evidence in the literature for pre-diagnostic biomarkers in glioma, including metabolomics and proteomics. We also consider the limitations of these approaches and future research directions of pre-diagnostic biomarkers for glioma.

Prospective investigation of herpesvirus infection and risk of glioma

Glioma is an aggressive neoplasm of the brain with poorly understood etiology. A limited number of pathogens have been examined as glioma risk factors, but data from prospective studies with infection status determined before disease are lacking. Herpesviruses comprise a large family of DNA viruses that infect humans and are linked to a range of chronic diseases. We conducted a prospective evaluation of the association between antibody to six human herpesviruses and glioma risk in the Janus Serum Bank (Janus) and the Cancer Prevention Study-II (CPS-II). In Janus and CPS-II, the risk for glioma was not related to seroprevalence of herpes simplex virus-1, varicella zoster virus, or human herpes viruses 6A or 6B. In Janus, seropositivity to either the Epstein Barr virus (EBV) EA[D] or VCAp18 antigen was associated with a lower risk of glioma (ORs: 0.55 [95% CI 0.32-0.94] and 0.57 [95% CI 0.38-0.85]). This inverse association was consistent by histologic subtype and was observed for gliomas diagnosed up to two decades following antibody measurement. In Janus, seropositivity to at least one of three examined cytomegalovirus (CMV) antigens (pp150, pp52, pp28) was associated with an increased risk of nonglioblastoma (OR: 2.08 [95% CI 1.07-4.03]). This association was limited to tumors diagnosed within 12 years of antibody measurement. In summary, we report evidence of an inverse association between exposure to EBV and glioma. We further report that CMV exposure may be related to a higher likelihood of the nonglioblastoma subtype.

VALZ-Pilot: High-dose valacyclovir treatment in patients with early-stage Alzheimer's disease

Introduction

Herpes simplex virus (HSV) may be involved in Alzheimer's disease (AD) pathophysiology. The antiviral valacyclovir inhibits HSV replication.

Methods

This phase-II pilot trial involved valacyclovir administration (thrice daily, 500 mg week 1, 1000 mg weeks 2-4) to persons aged ≥ 65 years with early-stage AD, anti-HSV immunoglobulin G, and apolipoprotein E ε4. Intervention safety, tolerability, feasibility, and effects on Mini-Mental State Examination (MMSE) scores and cerebrospinal fluid (CSF) biomarkers were evaluated.

Results

Thirty-two of 33 subjects completed the trial on full dosage. Eighteen percent experienced likely intervention-related mild, temporary adverse events. CSF acyclovir concentrations were mean 5.29 ± 2.31 μmol/L. CSF total tau and neurofilament light concentrations were unchanged; MMSE score and CSF soluble triggering receptor expressed on myeloid cells 2 concentrations increased (P = .02 and .03).

Discussion

Four weeks of high-dose valacyclovir treatment was safe, tolerable, and feasible in early-stage AD. Our findings may guide future trial design.

Presence of the Human Cytomegalovirus in Glioblastomas-A Systematic Review

Simple Summary

Whether the human cytomegalovirus (HCMV) is present in samples obtained from patients with glioblastoma (GBM) has been a matter under debate during the last two decades. Many investigators have demonstrated the presence of HCMV proteins and nucleic acids in GBM tumors, while some have not been able to detect it. It is important to evaluate current data and resolve these issues to clarify the possible role of the HCMV in GBM tumorigenesis and if this virus can serve as a potential target of therapy for these patients. In the present systematic review, we aim to review published research studies with a focus to identify differences and similarities in methods used for the detection of the HCMV in GBM samples found to be positive or negative for HCMV. Our data suggest that the HCMV is highly prevalent in glioblastomas and that optimized immunohistochemistry techniques are required to detect it.

Abstract

Glioblastoma is a malignant brain tumor with a dismal prognosis. The standard treatment has not changed in the past 15 years as clinical trials of new treatment protocols have failed. A high prevalence of the human cytomegalovirus (HCMV) in glioblastomas was first reported in 2002. The virus was found only in the tumor and not in the surrounding healthy brain tissue. Many groups have confirmed the presence of the HCMV in glioblastomas, but others could not. To resolve this discrepancy, we systematically reviewed 645 articles identified in different databases. Of these, 81 studies included results from 247 analyses of 9444 clinical samples (7024 tumor samples and 2420 blood samples) by different techniques, and 81 articles included 191 studies that identified the HCMV in 2529 tumor samples (36% of all tumor samples). HCMV proteins were often detected, whereas HCMV nucleic acids were not reliably detected by PCR methods. Optimized immunohistochemical techniques identified the virus in 1391 (84,2%) of 1653 samples. These data suggest that the HCMV is highly prevalent in glioblastomas and that optimized immunohistochemistry techniques are required to detect it.

Plasma Amyloid-β in Relation to Antibodies Against Herpes Simplex Virus, Cytomegalovirus, and Chlamydophila pneumoniae

Background:

Amyloid-β (Aβ), the key constituent of Alzheimer’s disease (AD) plaques, has antimicrobial properties.

Objective:

To investigate the association between plasma Aβ and antibodies against the AD-related pathogens herpes simplex virus (HSV), cytomegalovirus (CMV), and C. pneumoniae.

Methods:

Plasma from 339 AD cases, obtained on average 9.4 years (±4.00) before diagnosis, and their matched controls were analyzed for Aβ₄₀ and Aβ₄₂ concentrations with Luminex xMAP technology and INNOBIA plasma Aβ-form assays. Enzyme-linked immunosorbent assays were utilized for analyses of anti-HSV immunoglobulin (Ig) G, anti-HSV1 IgG, anti-HSV2 IgG, anti-CMV IgG, and anti-C. pneumoniae IgG. Follow-up samples were available for 150 of the cases.

Results:

Presence and levels of anti-HSV1 IgG, anti-HSV2 IgG, anti-CMV IgG, and anti-C. pneumoniae IgG did not correlate with concentrations of Aβ₄₂ or Aβ₄₀ in cases or controls.

Conclusion:

Levels of plasma Aβ were not associated with antibodies against different AD-related pathogens.

Early indicators of primary brain tumours: a population-based study with 10 years' follow-up

BACKGROUND AND PURPOSE

To improve diagnoses of primary brain tumours, knowledge about early indicators is needed. Nationwide Danish health registries were used to conduct a population-based case-control study including all persons diagnosed with a primary brain tumour between 2005 and 2014 in Denmark.

METHODS

All 5135 adults diagnosed with a primary brain tumour in the Danish Cancer Registry were matched to 19 572 general population comparisons from the Danish Civil Registration System. Conditional logistic regression analyses were applied to estimate age- and multivariable-adjusted odds ratios (ORs) for the occurrence of a primary brain tumour up to 10 years after hospital diagnoses or prescription of medications related to nervous system diseases and mental and behavioural disorders.

RESULTS

Increased odds for primary brain tumour after nervous system diseases and mental and behavioural disorders manifested up to 10 years before tumour diagnosis were found. Increased odds were seen especially for hospital contacts for inflammatory nervous system diseases [OR 11.3; 95% confidence interval (CI) 6.5-19.7], epilepsy (OR 9.0; 95% CI 7.6-10.7) and antiepileptic medications (OR 3.6; 95% CI 3.2-4.0), whilst antidementia medications provided a strong, protective association for primary brain tumours (OR 0.5; 95% CI 0.3-0.8).

CONCLUSIONS

Sub-groups of patients diagnosed with or being prescribed certain medications targeting nervous system diseases and mental and behavioural disorders may be at increased risk of being diagnosed with a primary brain tumour. Further studies should disentangle the potential underlying common pathogenetic pathways. The results are important for the development of systematic clinical approaches to ensure early diagnosis of primary brain tumours.

A genetic signature including apolipoprotein Eε4 potentiates the risk of herpes simplex-associated Alzheimer's disease

Introduction

Herpes simplex virus type 1 (HSV1) in combination with genetic susceptibility has previously been implicated in Alzheimer's disease (AD) pathogenesis.

Methods

Plasma from 360 AD cases, obtained on average 9.6 years before diagnosis, and their age- and sex-matched controls, were analyzed for anti-HSV1 immunoglobulin (Ig) G with enzyme-linked immunosorbent assays (ELISAs). A POE genotype and nine other selected risk genes for AD were extracted from a genome-wide association study analysis by deCODE genetics, Reykjavik, Iceland.

Results

The interaction between APOEε4 heterozygosity (APOEε2/ε4 or ε3/ε4) and anti-HSV1 IgG carriage increased the risk of AD (OR 4.55, P = .02). A genetic risk score based on the nine AD risk genes also interacted with anti-HSV1 IgG for the risk of developing AD (OR 2.35, P = .01).

Discussion

The present findings suggest that the APOEε4 allele and other AD genetic risk factors might potentiate the risk of HSV1-associated AD.

Epstein-Barr virus- and cytomegalovirus-specific immune response in patients with brain cancer

Background

Patients with brain tumor or pancreatic cancer exhibit the poorest prognosis, while immune fitness and cellular immune exhaustion impacts their survival immensely. This work identifies differences in the immune reactivity to the common human pathogens cytomegalovirus (CMV) and Epstein–Barr virus (EBV) between patients with brain tumor in comparison to those with pancreatic cancer and healthy individuals.

Methods

We characterized the humoral and cellular immune responses of patients with brain tumor or pancreatic cancer to cytomegalovirus structural protein pp65 (CMV-pp65) as well as Epstein–Barr nuclear antigen-1 (EBNA-1) by whole-blood assay and ELISA.

Results

Anti-CMV-pp65 plasma immunoglobulin gamma (IgG) titers were significantly lower in patients with brain tumor compared to healthy donors and patients with pancreatic cancer. Among the responding patients with GBM, those with a weak anti-CMV IgG response also had a decreased median overall survival (p = 0.017, 667 vs 419 days) while patients with brain tumor showed a generally suppressed anti-CMV immune-reactivity. Patients with brain tumor exhibited a significantly lower interferon gamma (IFNγ) response to EBNA-1 and CMV-pp65 compared to patients with pancreatic cancer or healthy donors. This antigen-specific response was further amplified in patients with brain tumor upon conditioning of whole blood with IL-2/IL-15/IL-21. Exclusively in this setting, among the responding patients with GBM, those exhibiting a EBV-specific cellular immune response above the median also displayed an increased median overall survival pattern compared to weak responders (753 vs 370 days, p < 0.001).

Conclusions

This report provides (i) a fast and easy assay using common viral antigens and cytokine stimulation to screen for immune fitness/exhaustion of patients with brain tumor in comparison to pancreatic cancer and healthy individuals and (ii) EBV/CMV-induced IFNγ production as a potential marker of survival in patients with brain tumor.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1557-9) contains supplementary material, which is available to authorized users.

Decreased human leukocyte antigen A*02:01 frequency is associated with risk of glioma and existence of human cytomegalovirus: a case-control study in Northern China

BACKGROUND

Human leukocyte antigens (HLAs) play an important role in host defense against viral infection and tumorigenesis. Human cytomegalovirus (HCMV) has been linked to glioma development. This study investigated the relationship between HLA distribution, presence of HCMV, and glioma development in a Han Chinese population.

METHODS

The study population included 150 glioma patients and 150 tumor-free brain injury control subjects (control-A) matched according to geography, ethnicity, age, and gender. HLA allele frequency was compared between the two groups using peripheral blood samples by PCR sequence-based typing. These data were also compared with HLA frequencies obtained from a Northern Chinese Han population database (control-B). HCMV DNA was detected in the peripheral blood of glioma patients and control group-A by nested PCR. The expression of HCMV proteins IE1-72 and pp65 in tumor tissues was evaluated by immunohistochemistry.

RESULTS

The frequency of HLA-A*02:01 was decreased in glioma patients as compared to control group-A and -B (P < 0.001 and P = 0.001, respectively). The age/sex-adjusted odds ratio for HLA-A*02:01 positivity vs. negativity was 0.392 (95% confidence interval 0.225-0.683). HCMV was more frequently detected in the peripheral blood and tumor tissue of HLA-A*02:01-negative glioma patients. HLA-A*02:01 and HCMV were not associated with overall survival.

CONCLUSION

There is a correlation between decreased HLA-A*0201 allele frequency and glioma susceptibility.

Herpes virus seroepidemiology in the adult Swedish population

Background

Herpes viruses establish a life-long latency and can cause symptoms during both first-time infection and later reactivation. The aim of the present study was to describe the seroepidemiology of Herpes simplex type 1 (HSV1), Herpes simplex type 2 (HSV2), Cytomegalovirus (CMV), Varicella Zoster virus (VZV) and Human herpes virus type 6 (HHV6) in an adult Swedish population (35–95 years of age).

Methods

Presence of antibodies against the respective viruses in serum from individuals in the Betula study was determined with an enzyme-linked immunosorbent assay (ELISA). Singular samples from 535 persons (53.9% women, mean age at inclusion 62.7 ± 14.4 years) collected 2003-2005 were analyzed for the five HHVs mentioned above. In addition, samples including follow-up samples collected 1988–2010 from 3,444 persons were analyzed for HSV.

Results

Prevalence of HSV1 was 79.4%, HSV2 12.9%, CMV 83.2%, VZV 97.9%, and HHV6 97.5%. Herpes virus infections were more common among women (p = 0.010) and a lower age-adjusted HSV seroprevalence was found in later birth cohorts (p < 0.001). The yearly incidence of HSV infection was estimated at 14.0/1000.

Conclusion

Women are more often seropositive for HHV, especially HSV2. Age-adjusted seroprevalence for HSV was lower in later birth cohorts indicating a decreasing childhood and adolescent risk of infection.

An overview of the infection of CMV, HSV 1/2 and EBV in Mexican patients with glioblastoma multiforme

Several risk factors are involved in glioblastoma, including cytomegalovirus (CMV). This research was carried out to determine the rate of CMV infection, as well as HSV 1/2 and EBV in brain tissue, in patients with glioblastomamultiforme (GBM). The tissues were tested using immunohistochemistry, PCR, in situ hybridization and real-time PCR. At least, one HHV was detected in 21/29 (72%) patients as follows: single infections with HSV-1/2 in 4/21 (19%), EBV in 6/21 (28.6%) and CMV in 1/21 (4.8%). Mixed viral infection, HSV-1/2 and EBV were detected in 4/21 patients (19%), CMV and EBV in 5/21 (23.8%), and HSV-1/2, EBV, and CMV in 1/21. The CMV viral load ranged from 3×10² to 4.33×10⁵ genome/100ng of tissue. Genotype based on CMV gB was 3/7 where 2/3 was gB1 and 1/3 gB4. HSV, EBV and CMV were frequently found in brain tissues, more in mix in a population reported as highly seropositive.

History of chickenpox in glioma risk: a report from the glioma international case-control study (GICC)

Varicella zoster virus (VZV) is a neurotropic α-herpesvirus that causes chickenpox and establishes life-long latency in the cranial nerve and dorsal root ganglia of the host. To date, VZV is the only virus consistently reported to have an inverse association with glioma. The Glioma International Case-Control Study (GICC) is a large, multisite consortium with data on 4533 cases and 4171 controls collected across five countries. Here, we utilized the GICC data to confirm the previously reported associations between history of chickenpox and glioma risk in one of the largest studies to date on this topic. Using two-stage random-effects restricted maximum likelihood modeling, we found that a positive history of chickenpox was associated with a 21% lower glioma risk, adjusting for age and sex (95% confidence intervals (CI): 0.65-0.96). Furthermore, the protective effect of chickenpox was stronger for high-grade gliomas. Our study provides additional evidence that the observed protective effect of chickenpox against glioma is unlikely to be coincidental. Future studies, including meta-analyses of the literature and investigations of the potential biological mechanism, are warranted.

A systematic review of the risk factors associated with the onset and progression of primary brain tumours

The overall aim of this systematic review was to identify risk factors for onset and natural progression, which were shown to increase, decrease, or have a null association with risk of primary brain tumour. For onset, the project was separated into two phases. The first phase consisted of a systematic search of existing systematic reviews and meta-analyses. Moderate to high methodological quality reviews were incorporated and summarized with relevant observational studies published since 2010, identified from a systematic search performed in phase 2. For natural progression, only the first phase was conducted. Standard systematic review methodology was utilized. Based on this review, various genetic variants, pesticide exposures, occupational farming/hairdressing, cured meat consumption and personal hair dye use appear to be associated with increased risk of onset amongst adults. The specific EGF polymorphsm 61-A allele within Caucasian populations and having a history of allergy was associated with a decreased risk. For progression, M1B-1 antigen was shown to increase the risk. High birth weight, pesticide exposure (childhood exposure, and parental occupational exposure) and maternal consumption of cured meat during pregnancy may also increase the risk of onset of childhood brain tumours. Conversely, maternal intake of pre-natal supplements (folic acid) appeared to decrease risk. Children with neurofibromatosis 2 were considered to have worse overall and relapse free survival compared to neurofibromatosis 1, as were those children who had grade III tumours compared to lesser grades.

Detection of human cytomegalovirus in different histopathological types of glioma in Iraqi patients

Human Cytomegalovirus (HCMV) is an endemic herpes virus that reemerges in cancer patients enhancing oncogenic potential. HCMV infection is associated with certain types of cancer morbidity such as glioblastomas. HCMV, like all other herpes viruses, has the ability to remain latent within the body of the host and can contribute in chronic inflammation. To determine the role of HCMV in glioma pathogenesis, paraffin-embedded blocks from glioma patients (n = 50) and from benign meningioma patients (n = 30) were obtained and evaluated by immunohistochemistry and polymerase chain reaction for the evidence of HCMV antigen expression and the presence of viral DNA. We detected HCMV antigen and DNA for IEI-72, pp65, and late antigen in 33/36, 28/36, and 26/36 in glioblastoma multiforme patients whereas 12/14, 10/14, and 9/14 in anaplastic astrocytoma patients, respectively. Furthermore, 84% of glioma patients were positive for immunoglobulin G (IgG) compared to 72.5% among control samples (P = 0.04). These data indicate the presence of the HCMV virus in a high percentage of glioma samples demonstrating distinct histopathological grades and support previous reports showing the presence of HCMV infection in glioma tissue. These studies demonstrate that detection of low-levels of latent viral infections may play an active role in glioma development and pathogenesis.

Cytomegalovirus and glioma: putting the cart before the horse

In 1908, Oluf Bang and Vilhelm Ellerman laid the foundation for theory of oncoviruses by demonstrating that the avian erythroblastosis (a form of chicken leukaemia) could be transmitted by cell-free extracts. Since then, it has been shown very convincingly that viruses can directly cause several human cancers by various mechanisms. Epidemiological data imply that viruses are the second most important risk factor for cancer development in humans, exceeded only by tobacco consumption. Although the ability of certain viruses (hepatitis B and C, human papillomavirus, etc) to cause cancer has been time tested and proven scientifically, there are several other potential viral candidates whose role in oncogenesis is more controversial. One such controversial scenario involves the role of cytomegalovirus (CMV) in malignant gliomas, the most common form of primary brain tumour. CMV first attracted attention about a decade ago when CMV gene products were found in glioma tissue but not in normal brain. Since this initial observation, several different groups have shown an oncomodulatory effect of CMV; however, direct association between CMV infection and incidence of glioma is lacking. In this review, we will evaluate the evidence, both preclinical and clinical, regarding the possible role of CMV in gliomagenesis and maintenance. We will also critically evaluate the rationale for using antiviral drugs in the treatment of patients with glioma.

Human cytomegalovirus infection in tumor cells of the nervous system is not detectable with standardized pathologico-virological diagnostics

BACKGROUND

Experimental findings have suggested that human cytomegalovirus (HCMV) infection of tumor cells may exert oncomodulatory effects that enhance tumor malignancy. However, controversial findings have been published on the presence of HCMV in malignant tumors. Here, we present the first study that systematically investigates HCMV infection in human nervous system tumors by highly sensitive immunohistochemistry in correlation with the HCMV serostatus of the patients.

METHODS

Immunohistochemical and quantitative PCR-based methods to detect different HCMV antigens and genomic HCMV DNA were optimized prior to the investigation of pathological samples. Moreover, the pathological results were matched with the HCMV serostatus of the patients.

RESULTS

HCMV immediate-early, late, and pp65 antigens could be detected in single cells from HCMV strain Hi91-infected UKF-NB-4 neuroblastoma cells after 1:1024 dilution with noninfected UKF-NB-4 cells. Genomic HCMV DNA could be detected in copy numbers as low as 430 copies/mL. However, we did not detect HCMV in tumors from a cohort of 123 glioblastoma, medulloblastoma, or neuroblastoma patients. Notably, we detected nonspecifically positive staining in tumor tissues of HCMV seropositive and seronegative glioblastoma patients. The HCMV serostatus of 67 glioblastoma patients matched the general epidemiological prevalence data for Western countries (72% of female and 57% of male glioblastoma patients were HCMV seropositive). Median survival was not significantly different in HCMV seropositive versus seronegative glioblastoma patients.

CONCLUSIONS

The prevalence of HCMV-infected tumor cells may be much lower than previously reported based on highly sensitive detection methods.

Interaction of allergy history and antibodies to specific varicella-zoster virus proteins on glioma risk

Glioma is the most common cancer of the central nervous system but with few confirmed risk factors. It has been inversely associated with chicken pox, shingles and seroreactivity to varicella virus (VZV), as well as to allergies and allergy-associated IgE. The role of antibody reactivity against individual VZV antigens has not been assessed. Ten VZV-related proteins, selected for high immunogenicity or known function, were synthesized and used as targets for antibody measurements in the sera of 143 glioma cases and 131 healthy controls selected from the San Francisco Bay Area Adult Glioma Study. Glioma cases exhibited significantly reduced seroreactivity compared to controls for six antigens, including proteins IE63 [odds ratio (OR) = 0.26, 95% confidence interval (CI): 0.12-0.58, comparing lowest quartile to highest) and the VZV-unique protein ORF2p (OR = 0.44, 95% CI: 0.21-0.96, lowest quartile to highest). When stratifying the study population into those with low and high self-reported allergy history, VZV protein seroreactivity was only associated inversely with glioma among individuals self-reporting more than two allergies. The data provide insight into both allergy and VZV effects on glioma: strong anti-VZV reactions in highly allergic individuals are associated with reduced occurrence of glioma. This result suggests a role for specificity in the anti-VZV immunity in brain tumor suppression for both individual VZV antigens and in the fine-tuning of the immune response by allergy. Anti-VZV reactions may also be a biomarker of effective CNS immunosurveillance owing to the tropism of the virus.

Antihistamine use and immunoglobulin E levels in glioma risk and prognosis

OBJECTIVE

An inverse association between personal history of allergies/asthma and glioma risk has been fairly consistently reported in the epidemiologic literature. However, the role of regular antihistamine use remains controversial due to a small number of studies reporting contradictory findings. We evaluated the association between regular use of oral antihistamines and glioma risk, adjusting for a number of relevant factors (e.g., immunoglobulin E levels and history of chickenpox).

METHODS

We used a subset of the Harris County Case-Control Study, which included 362 pathologically confirmed glioma cases and 462 cancer-free controls, to evaluate this association using unconditional multivariable logistic regression. These models were run among the overall study population and stratified by allergy status. Cox regression was utilized to examine whether antihistamine use was associated with mortality among all cases and separately among high-grade cases.

RESULTS

Antihistamine use was strongly associated with glioma risk among those with a positive allergy/asthma history (OR: 4.19, 95% CI: 2.06-8.51), but not among those with a negative history (OR: 1.59, 95% CI: 0.95-2.67). There were no significant associations between antihistamine use and survival among cases.

CONCLUSION

The current study implies that regular antihistamine use may increase glioma risk. However, several larger studies are necessary before definitive conclusions can be drawn.

Early life exposures and the risk of adult glioma

Exposure to common infections in early life may stimulate immune development and reduce the risk for developing cancer. Birth order and family size are proxies for the timing of exposure to childhood infections with several studies showing a reduced risk of glioma associated with a higher order of birth (and presumed younger age at infection). The aim of this study was to examine whether birth order, family size, and other early life exposures are associated with the risk of glioma in adults using data collected in a large clinic-based US case-control study including 889 glioma cases and 903 community controls. A structured interviewer-administered questionnaire was used to collect information on family structure, childhood exposures and other potential risk factors. Logistic regression was used to calculate odds ratios (OR) and corresponding 95% confidence intervals (CI) for the association between early life factors and glioma risk. Persons having any siblings were at significantly lower risk for glioma when compared to those reporting no siblings (OR=0.64; 95% CI 0.44-0.93; p=0.020). Compared to first-borns, individuals with older siblings had a significantly lower risk (OR=0.75; 95% CI 0.61-0.91; p=0.004). Birth weight, having been breast fed in infancy, and season of birth were not associated with glioma risk. The current findings lend further support to a growing body of evidence that early exposure to childhood infections reduces the risk of glioma onset in children and adults.

Risk factors for gliomas. An extensive review

Primary brain tumors consist are a heterogenic group of malignancies. Gliomas represent subtypes which include all tumors arising from glial cells. The risk factors for gliomas are until today unclear. The aim of this study was to summarize all possible connections between suspected risk factors and glial brain tumors.

Anti-human-cytomegalovirus immunoglobulin G levels in glioma risk and prognosis

The role of human cytomegalovirus (HCMV) in glioma development and progression remains controversial. The purpose of our study was to assess the potential associations between anti-HCMV antibodies (immunoglobulin G [IgG] and immunoglobulin M [IgM]) and glioma risk and prognosis using data from the Harris County Case–Control Study. Multivariable logistic regression models were utilized to estimate odds ratios and 95% confidence intervals (CI) for the associations between glioma status and antibody levels among glioma cases (n = 362) and cancer-free controls (n = 462). Hazard ratios and 95% CIs were calculated using Cox proportional hazards regression, adjusting for age, race, and sex, to determine if antibody levels were associated with survival over time among cases. Among IgG-positive participants, increasing anti-HCMV IgG levels were associated with decreasing glioma risk (P for trend = 0.0008), and those with the lowest level of anti-HCMV IgG (<10 U/mL) had the highest glioma risk, controlling for age, sex, and race/ethnicity (OR: 2.51, 95% CI: 1.42–4.43). Antibody levels were not associated with survival among glioma cases. Our study contributes new evidence toward the potential importance of the direct and indirect effects of HCMV infection in gliomagenesis.