Association between Epstein-Barr virus infection and risk for development of pregnancy-associated breast cancer: joint effect with vitamin D?

Breast cancer and cytomegalovirus

PURPOSE

To determine whether cytomegalovirus is causally associated with breast cancer and whether cytomegalovirus should be categorised as an oncogenic virus.

METHODS

We undertook a review of published epidemiological and laboratory studies, using established causal criteria: Bradford Hill criteria to determine whether cytomegalovirus is associated with breast cancer; and Evans/Mueller criteria to determine whether cytomegalovirus should be categorised as an oncogenic virus.

RESULTS

Although there are inconsistencies in the findings of published epidemiological and laboratory studies, these may be explained by factors such as: differences in timing of blood samples, differences in selection of cases and controls, or high cytomegalovirus seroprevalence among participants in the epidemiological studies; and, in the laboratory studies, differences in sample preparations, age of sample, whether or not paired breast cancer and normal breast tissue samples were used, differences in the tests, primers and/or antibodies used, differences in histological types of breast cancer studied, and/or features of the virus.

CONCLUSIONS

Overall, the results of published studies of cytomegalovirus and breast cancer suggest cytomegalovirus is a causal factor for at least some types of breast cancer. If the evidence for a link between cytomegalovirus and breast cancer continues to strengthen, further research could lead to: targeted screening; therapy using antiviral drugs; and, perhaps, primary prevention of a significant proportion of breast cancer. Vaccination against viruses has already been shown to be effective in preventing cervix and liver cancer; cytomegalovirus vaccines are already under development.

Immunostimulation in the treatment for chronic fatigue syndrome/myalgic encephalomyelitis

Chronic fatigue syndrome (CFS)/myalgic encephalomyelitis (ME) has long been associated with the presence of infectious agents, but no single pathogen has been reliably identified in all patients with the disease. Recent studies using metagenomic techniques have demonstrated the presence of thousands of microbes in the human body that were previously undetected and unknown to science. More importantly, such species interact together by sharing genes and genetic function within communities. It follows that searching for a singular pathogen may greatly underestimate the microbial complexity potentially driving a complex disease like CFS/ME. Intracellular microbes alter the expression of human genes in order to facilitate their survival. We have put forth a model describing how multiple species-bacterial, viral, and fungal-can cumulatively dysregulate expression by the VDR nuclear receptor in order to survive and thus drive a disease process. Based on this model, we have developed an immunostimulatory therapy that is showing promise inducing both subjective and objective improvement in patients suffering from CFS/ME.

Exacerbated metastatic disease in a mouse mammary tumor model following latent gammaherpesvirus infection

Background

Controversy exists as to the ability of human gammaherpesviruses to cause or exacerbate breast cancer disease in patients. The difficulty in conducting definitive human studies can be overcome by investigating developing breast cancer in a mouse model. In this study, we utilized mice latently infected with murine gammaherpesvirus 68 (HV-68) to question whether such a viral burden could exacerbate metastatic breast cancer disease using a mouse mammary tumor model.

Results

Mice latently infected with HV-68 had a similar primary tumor burden, but much greater metastatic disease, when compared to mock treated mice given the transplantable tumor, 4 T1. This was true for lung lesions, as well as secondary tumor masses. Increased expression of pan-cytokeratin and VEGF-A in tumors from HV-68 infected mice was consistent with increased metastatic disease in these animals. Surprisingly, no viral particles could be cultured from tumor tissues, and the presence of viral DNA or RNA transcripts could not be detected in primary or secondary tumor tissues.

Conclusions

Latent HV-68 infection had no significant effect on the size of primary 4 T1 mammary tumors, but exacerbated the number of metastatic lung lesions and secondary tumors when compared to mock treated mice. Increased expression of the tumor marker, pan-cytokeratin, and VEGF-A in tumors of mice harboring latent virus was consistent with an exacerbated metastatic disease. Mechanisms responsible for this exacerbation are indirect, since no virus could be detected in cancerous tissues.

Joint effects of Epstein-Barr virus and polymorphisms in interleukin-10 and interferon-γ on breast cancer risk

BACKGROUND

The relationship between Epstein-Barr virus (EBV) and breast cancer (BC) is controversial. Interleukin-10 (IL-10) and interferon-γ (IFN-γ) are believed to play a critical role in the host's responses to EBV infection, and their genetic variations may modify the association of EBV with BC risk.

METHODS

We examined serum levels of EBV viral capsid antigen (VCA) immunoglobulin A (IgA) and nuclear antigen-1 (EBNA-1) IgA along with the polymorphisms of IL-10 rs1800871 and IFN-γ rs2069705 in 354 incident BC cases and 504 age-matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multivariate logistic regression.

RESULTS

VCA IgA and EBNA-1 IgA levels were positively associated with BC risk. IL-10 rs1800871 (TC/CC) was associated with a reduced BC risk (OR, 0.74 [95% CI, 0.55-1.00]) but had no interaction with EBV infection on BC risk. IFN-γ rs2069705 was not directly associated with BC risk but interacted with EBNA-1 IgA on BC risk. Among women with the CC genotype, EBNA-1 IgA seropositivity significantly increased the risk of BC compared to EBNA-1 IgA seronegativity (OR, 5.14 [95% CI, 1.76-14.98]).

CONCLUSIONS

These results suggest that EBV may contribute to the risk of BC and that this contribution may be modified by genetic variations in IFN-γ.

Immunostimulation in the era of the metagenome

Microbes are increasingly being implicated in autoimmune disease. This calls for a re-evaluation of how these chronic inflammatory illnesses are routinely treated. The standard of care for autoimmune disease remains the use of medications that slow the immune response, while treatments aimed at eradicating microbes seek the exact opposite-stimulation of the innate immune response. Immunostimulation is complicated by a cascade of sequelae, including exacerbated inflammation, which occurs in response to microbial death. Over the past 8 years, we have collaborated with American and international clinical professionals to research a model-based treatment for inflammatory disease. This intervention, designed to stimulate the innate immune response, has required a reevaluation of disease progression and amelioration. Paramount is the inherent conflict between palliation and microbicidal efficacy. Increased microbicidal activity was experienced as immunopathology-a temporary worsening of symptoms. Further studies are needed, but they will require careful planning to manage this immunopathology.