Geographic similarities between varicella and multiple sclerosis: an hypothesis on the environmental factor of multiple sclerosis

Chickenpox and multiple sclerosis: A Mendelian randomization study

Observational studies have suggested a suspected association between varicella-zoster virus (VZV) infection and multiple sclerosis (MS), but the connection has remained unclear. The aim of the present study is to evaluate the causal relationship between chickenpox which is caused by VZV infection and MS. We performed a two-sample Mendelian randomization analysis to investigate the association of chickenpox with MS using summary statistics from genome-wide association studies (GWAS). The GWAS summary statistics data for chickenpox was from the 23andMe cohort including 107 769 cases and 15 982 controls. A large summary of statistical data from the International Multiple Sclerosis Genetics Consortium (IMSGC) was used as the outcome GWAS data set, including 14 802 MS cases and 26 703 controls. We found evidence of a significant association between genetically predicted chickenpox and risk of MS (odds ratio [OR] = 35.27, 95% confidence interval [CI] = 22.97-54.17, p = 1.46E-59). Our findings provided evidence indicating a causal effect of chickenpox on MS. Further elucidations of this association and underlying mechanisms are needed for identifying feasible interventions to promote MS prevention.

Association of Multiple Sclerosis with PM 2.5 levels. Further evidence from the highly polluted area of Padua Province, Italy

BACKGROUND

Fifty years of epidemiological survey and intra-regional differences in prevalence suggest that environmental factors may be associated with increased multiple sclerosis (MS) risk in Northern Italy. Based on the findings of a previous study carried out in the highly polluted Padan Plain, we further explored the relationship between PM2.5 levels and MS prevalence by comparing bordering areas characterized by quite different environmental conditions, namely the Municipality of Padua and the special protected zone (SPZ) of the Euganean Hills Regional Park, located 15 km from the City.

METHODS

Three territories were identified; 1) the SPZ, extending over an area of 15.096 hectares and having a total population of 23,980 inhabitants, 2) the urban area of Padua, with a total population of 210,440 inhabitants and repeatedly recognized by the European Invironmental Agency as one of the most polluted Cities of Europe, 3) the Intermediate Zone (IZ), i.e., the area in between the previous two, including part of the urban territories of eight villages adjacent to the SPZ. Demographic and socio-economical data were obtained from official government sources (www.istat.it and www.regione.veneto.it). All Italian MS patients residing in these three areas on December 31, 2018, were registered. PM2.5 concentrations (annual average 1998-2018, μg/m3) were measured by satellite. The correlation between PM2.5 concentrations and MS prevalence was analysed.

RESULTS

MS prevalence was significantly higher in Padua City (265/100.000) compared to both the SPZ of the Euganean Hills Park (160/100,000; p < 0.0001) and the IZ (194.4/100,000). Prevalence strongly associated with the annual average concentration of PM2.5 (r = 0.89 p < 0.00001).

CONCLUSION

In the Province of Padua, one of the most polluted areas of Europe, MS prevalence is strongly associated with PM2.5 exposure. Our findings suggest that air pollutants may be one of the possible environmental risk factors for MS in the Veneto Region of Italy.

The participation of varicella zoster virus in relapses of multiple sclerosis

OBJECTIVE

Recent studies have documented the apparent participation of varicella zoster virus (VZV) in the etiopathogenesis of multiple sclerosis (MS). The present study aimed to corroborate the possible presence of VZV during exacerbations of MS.

DESIGN

Fifty-three patients with definite MS were included; of them, 31 were studied during the first week of a clinical relapse, whereas 16 were studied during remission; 6 patients with progressive MS were also studied. Genes from 5 herpes viruses: varicella zoster, herpes simplex 1 and 2, Epstein-Barr and herpes 6 were studied by polymerase chain reaction in cerebrospinal fluid and in peripheral blood mononuclear cells (PBMC). As controls 21 patients with inflammatory or functional neurological disorders were included.

RESULTS

DNA from varicella zoster virus was found in the CSF from all MS patients studied during relapse (100%) and in the PBMC from 28 of them (90%). However, VZV DNA was found in the CSF only in 5 MS patients studied during remission (31%) and in the PBMC from 3 of them (19%). VZV DNA was also found, but in lower amounts, in the CSF (83%) and PBMC (33%) from patients with progressive MS. In contrast, VZV was not found either in CSF or in PBMC from controls. Results from the other herpes viruses tested were similar in MS patients and in controls.

CONCLUSIONS

Our results corroborate the conspicuous, but ephemeral presence of VZV during relapses of MS and support the idea of VZV involvement in the etiopathogenesis of MS. Recent epidemiological and molecular studies as well as reports of severe VZV infections triggered by specifically induced immunosuppression during therapy of MS give additional support to this potential association.

Infections and multiple sclerosis

Multiple sclerosis is a chronic inflammatory condition of unknown cause. Increasing evidence suggests that the disease develops as a result of interactions between the environment and the immune system in genetically susceptible individuals. It has long been recognized that infections may serve as environmental triggers for the disease, and a large number of pathogens have been proposed to be associated with multiple sclerosis. Here, we detail the historical basis linking infections to multiple sclerosis and review the epidemiology of the disease, which suggests a possible relationship with infectious agents. We also describe pathophysiologic studies in animals and other human demyelinating diseases that have demonstrated a variety of mechanisms by which infectious agents may induce chronic, relapsing central nervous system disease with myelin damage and relative preservation of axons, similar to multiple sclerosis. In addition, we discuss recent studies in individuals with multiple sclerosis indicating enhanced immune responses to infectious antigens, though not consistently demonstrating evidence for ongoing infection. Taken together, these studies suggest a role for infectious agents in the development of multiple sclerosis. Conclusive evidence, however, remains lacking.

Viruses and neurodegeneration

Neurodegenerative diseases (NDs) are chronic degenerative diseases of the central nervous system (CNS), which affect 37 million people worldwide. As the lifespan increases, the NDs are the fourth leading cause of death in the developed countries and becoming increasingly prevalent in developing countries. Despite considerable research, the underlying mechanisms remain poorly understood. Although the large majority of studies do not show support for the involvement of pathogenic aetiology in classical NDs, a number of emerging studies show support for possible association of viruses with classical neurodegenerative diseases in humans. Space does not permit for extensive details to be discussed here on non-viral-induced neurodegenerative diseases in humans, as they are well described in literature.Viruses induce alterations and degenerations of neurons both directly and indirectly. Their ability to attack the host immune system, regions of nervous tissue implies that they can interfere with the same pathways involved in classical NDs in humans. Supporting this, many similarities between classical NDs and virus-mediated neurodegeneration (non-classical) have been shown at the anatomic, sub-cellular, genomic and proteomic levels suggesting that viruses can explain neurodegenerative disorders mechanistically. The main objective of this review is to provide readers a detailed snapshot of similarities viral and non-viral neurodegenerative diseases share, so that mechanistic pathways of neurodegeneration in human NDs can be clearly understood. Viruses can guide us to unveil these pathways in human NDs. This will further stimulate the birth of new concepts in the biological research, which is needed for gaining deeper insights into the treatment of human NDs and delineate mechanisms underlying neurodegeneration.

The long and evolving relationship between viruses and multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disorder of unknown etiology, possibly caused by a virus or is virus-triggered. Several viruses, including herpesviruses, were suggested as etiologic agents or risk factors for exacerbation in the course of illness but none have been shown to be irrefutably linked. Recently the interest of researchers and clinicians in the association between viruses and MS was reawakened by the development of progressive multifocal leukoencephalopathy, a demyelinating and fatal disease caused by JC polyomavirus replication, in natalizumab-treated MS patients. In this review, we will illustrate the evidence underlying the viral hypothesis for MS pathogenesis and will review the main features of the potential viral candidates. We will also describe the risks associated with newer MS therapies and with viral/bacterial vaccinations.

Antibody response in seropositive multiple sclerosis patients vaccinated with attenuated live varicella zoster virus

OBJECTIVE

To determine the safety and effectiveness of live attenuated varicella zoster virus (VZV) vaccine (OKA/Merck) on 50 patients with chronic progressive multiple sclerosis (MS), based on the hypothesis that VZV might be the antigen or antigen mimic of MS plus the fact that repeated high antigen doses have produced 'antigen paralysis' in experimental allergic encephalomyelitis mice.

DESIGN

Fifty patients were randomly selected without controls. They were assessed clinically at entry and on four other occasions over 14 months. Enhanced cranial magnetic resonance imaging (MRI) was performed at entry and at six and 12 months post entry. All were vaccinated after initial assessment and again six weeks later.

SETTING

All clinical and laboratory assessments were performed at the Health Sciences Centre, Winnipeg, in the out-patient department. All MRI examinations were performed at the St Boniface General Hospital, Winnipeg, Manitoba. Both are tertiary care hospitals.

POPULATION STUDIED

Fifty randomly selected patients with chronic progressive MS, age 18 to 60 years, and a disability status scale of 2.0 or greater were included. Forty-five patients completed the study.

INTERVENTIONS

Two vaccinations with attenuated live VZV six weeks apart.

RESULTS

All patients were VZV seropositive at entry and all showed an increased antibody level following vaccination. No one was harmed by the vaccine. There may have been some changes in the MS of 15 patients.

CONCLUSIONS

It may be reasonable and safe to challenge the process of MS using large doses of the immunogenic proteins of the VZV to induce 'immune paralysis'.

Varicella zoster virus and relapsing remitting multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated disorder; however, little is known about the triggering factors of the abnormal immune response. Different viruses from the herpes family have been mentioned as potential participants. Here, we review the evidences that support the association of varicella zoster virus (VZV) with MS. Epidemiological studies from geographical areas, where incidence of MS has increased in recent decades, pointed out a high frequency of varicella and zoster in the clinical antecedents of MS patients, and also laboratory investigations have found large quantities of DNA from VZV in leucocytes and cerebrospinal fluid of MS patients restricted to the ephemeral period of MS relapse, followed by disappearance of the virus during remission. The above observations and the peculiar features of VZV, mainly characterized by its neurotropism and long periods of latency followed by viral reactivation, support the idea on the participation of VZV in the etiology of MS. However, as with reports from studies with other viruses, particularly Epstein Barr virus, conflicting results on confirmatory studies about the presence of viral gene products in brain tissue indicate the need for further research on the potential participation of VZV in the etiology of MS.

Immunogenicity and Reactogenicity of a Single Dose of Live Attenuated Varicella Vaccine and a Booster Dose of Measles–Mumps–Rubella Vaccine Given Concomitantly at 12 years of Age

Universal varicella-zoster virus (VZV) childhood vaccination is still debated, but adult chickenpox may be severe. It could be prevented by vaccination of seronegative adolescents. This study aimed to determine the feasibility of coadministration of a VZV vaccine and the measles-mumps-rubella (MMR) booster at 12 y of age. Guardians of 1231 12-y-old pupils where asked about the history of chickenpox in their children. 190 had no chickenpox history and 12 of 62 of them lacked VZV antibodies. Additional history-negative children were also recruited. 199 history-positive children received only MMR and 98 history-negative children received an MMR vaccine and a VZV vaccine. Serum samples were drawn before vaccination and after 8 weeks. Viral antibodies were measured by immunofluorescence (VZV) and enzyme-linked immunosorbent assays (VZV, MMR). All 184 history-positive children tested had VZV antibodies. 17/89 VZV-vaccinated and tested children (19%) lacked VZV antibodies before vaccination. 12 (71%) seroconverted after 1 dose. Cell-mediated immunity (CMI) against varicella was tested in 3/5 children who did not seroconvert after 1 dose of VZV vaccine. They seroconverted after a second dose and had measurable CMI. VZV vaccination did not affect the MMR response and there were no severe side-effects. A history of varicella infection, as reported by the guardian, is reliable, but a negative history was incorrect in 81% of the cases. This population of 12-y-old children may require 2 doses of VZV vaccine, at least when given simultaneously with the MMR vaccine.

Increased prevalence of varicella zoster virus DNA in cerebrospinal fluid from patients with multiple sclerosis

In order to investigate the possible involvement of viruses in Multiple Sclerosis (MS), the study evaluated the presence of viral genomic sequences in cerebrospinal fluid (CSF), as markers of viral replication within the central nervous system (CNS). A total of 85 CSF samples were collected from 38 MS patients, 28 patients with other neurological diseases and 19 subjects without neurological diseases. Using nested-PCR, the investigation focused on the presence of human herpes virus DNA, including herpes simplex virus 1 (HSV-1) and 2 (HSV-2), the Epstein-Barr virus (EBV), varicella zoster virus (VZV), human cytomegalovirus (HCMV), human herpes virus 6 (HHV-6) and JC virus (JCV). All the CSF samples from the individuals without neurological diseases were negative for viral DNA. Genomic sequences of HSV-1, HCMV, EBV, HHV6, and JCV were found in patients with MS and other neurological diseases without significant differences between the two groups. VZV DNA was detected more frequently (P < 0.05) in the MS group (31.6%), particularly among the relapsing-remitting MS patients (43.5%), compared with patients with other neurological diseases (10.7%). In addition, the results indicated that JCV and HHV-6 were replicating actively in the CNS of a small, but significant number of patients with MS and other neurological diseases. Most importantly, the study revealed a high frequency of VZV DNA in the CSF of patients with MS, suggesting a possible role of this virus in the pathogenesis of MS.

Frequent association of multiple sclerosis with varicella and zoster

BACKGROUND

A possible association of multiple sclerosis (MS) with viral diseases has been postulated; in previous studies we have found that in Mexican mestizos the antecedent of varicella during childhood represents a risk factor for the development of MS during adulthood.

AIM

We conducted a retrospective search for varicella and zoster infections associated with the development of MS.

METHODS AND RESULTS

In a cohort of 82 consecutive patients with MS we found six cases, four of varicella and two of zoster, that were concurrent with the development or the progress of MS.

CONCLUSIONS

The association of these pathologies is higher than expected and suggests a possible etiological relationship of the varicella zoster virus with MS.

Varicella, ephemeral breastfeeding and eczema as risk factors for multiple sclerosis in Mexicans

OBJECTIVE

It has been suggested that the incidence of multiple sclerosis (MS) in Mexico and other countries of Latin America has increased steadily for the last two decades. We made a thorough search of antecedents on MS patients that could be potential risk factors.

METHODS

A case-control study was conducted using a questionnaire that included demographic, nutritional, infectious and personal antecedents previously identified in other reports as possible risk factors for MS.

RESULTS

The frequency of varicella, ephemeral breastfeeding and eczema in the medical history of MS patients were significant when compared with controls; all appeared to be mutually additive. However, they were unrelated with clinical characteristics or disease severity.

CONCLUSION

During the last decades, breastfeeding has been abandoned in large segments of society and the incidence of varicella and childhood eczema keeps a north-south gradient similar to that described for MS. These factors may participate in the sharp increase of MS in countries like Mexico traditionally considered as an area of very low incidence.

In vivo survival of viral antigen-specific T cells that induce experimental autoimmune encephalomyelitis

A peptide derived from the human papillomavirus L2 protein is recognized by a myelin basic protein (MBP)-specific T cell clone from a multiple sclerosis patient and by MBP-specific autoantibodies purified from multiple sclerosis brain tissue. We now show in mice that low doses of this papillomavirus peptide were optimal in selecting a subpopulation of papillomavirus peptide-specific T cells that cross-reacted with MBP(87-99) and with an unrelated viral peptide derived from the BSLF1 protein of Epstein-Barr virus (EBV). These low dose viral peptide- specific T cell lines were highly encephalitogenic. Splenocytes from mice transferred with viral peptide-specific T cells showed a vigorous response to both the papillomavirus and MBP peptides, indicating that viral antigen-specific T cells survived for a prolonged time in vivo. The EBV peptide, unable to prime and select an autoreactive T cell population, could still activate the low dose papillomavirus peptide-specific cells and induce central nervous system (CNS) autoimmunity. Cytokine profiles of papillomavirus peptide-specific encephalitogenic T cells and histopathology of CNS lesions resembled those induced by MBP. These results demonstrate conserved aspects in the recognition of the self-antigen and a cross-reactive viral peptide by human and murine MBP-specific T cell receptors. We demonstrate that a viral antigen, depending on its nature, dose, and number of exposures, may select autoantigen-specific T cells that survive in vivo and can trigger autoimmune disease after adoptive transfer.

The varicella-zoster virus and multiple sclerosis

This article is a review of the evidence suggesting a unique relationship between the varicella-zoster virus (as a possible antigen or antigen mimic) and multiple sclerosis (MS). Both MS and varicella have increased prevalences in temperate zones and both are rare in countries closer to the equator. Migration studies suggest an infectious agent acquired prior to age 14 plays a role in the risk of subsequent MS. Hutterites, who educate their children at home, have less varicella, MS, and herpes zoster than their neighbors and have the appropriate reduced varicella-zoster seropositivity matching these clinical observations. Paradoxically, patients with MS report more herpes zoster, and at an earlier age and more often, than a group of non-MS patients.

Multiple sclerosis: a geographical hypothesis

Multiple sclerosis remains a rare neurological disease of unknown aetiology, with a unique distribution, both geographically and historically. Rare in equatorial regions, it becomes increasingly common in higher latitudes; historically, it was first clinically recognized in the early nineteenth century. A hypothesis, based on geographical reasoning, is here proposed: that the disease is the result of a specific vitamin deficiency. Different individuals suffer the deficiency in separate and often unique ways. Evidence to support the hypothesis exists in cultural considerations, in the global distribution of the disease, and in its historical prevalence.

Varicella zoster antibodies after herpes zoster, varicella and multiple sclerosis

BACKGROUND

We previously showed that Manitoba Hutterites seek physician care for varicella zoster virus infection significantly less than non-Hutterites. The current study was undertaken to measure varicella zoster virus seroprevalence for Hutterite and non-Hutterite controls.

METHODS

Blood was obtained from 315 Hutterites and 259 similar age and sex controls at the time of blood donations to The Canadian Red Cross Society. The controls were from the same or a contiguous postal code area and were collected at the same time as the Hutterite samples. The immune status of the specimens was determined by the ELISA method (enzyme linked immunosorbent assay).

RESULTS

Twenty-eight per cent of 315 Hutterites had no immunity and an additional 25% had only marginal immunity. Among the 259 controls, 10% had no immunity and an additional 10% had only marginal immunity (p < .0001).

CONCLUSIONS

Manitoba Hutterites have significantly decreased seroprevalence to varicella zoster virus infection. This study of serum varicella zoster virus antibodies verifies a previous population based study that demonstrated the relative rarity of varicella and herpes zoster among a particular population group.

Common infectious diseases in a population with low multiple sclerosis and varicella occurrence

A previous study revealed the rarity of varicella zoster virus (VZV) diseases among 5601 Hutterite Brethren living in a high-risk area for these diseases. The current study was established to determine the frequency of other common infectious diseases. The information was gathered from a population-based study of a unique group of Manitoba citizens and compared with an equal number of their age and sex-matched neighbors. The data were contained in the records of the Manitoba Health Services Commission (MHSC). The MHSC, the sole paying agency for medical diseases in Manitoba, contained 94,383,972 records for all of Manitoba for the years 1985 to 1991 inclusive. From these, the records of a cohort of 5601 Hutterites and an equal number of non-Hutterite age- and sex-matched controls were examined for the frequency of 14 diseases of interest. To be eligible a Hutterite subject must have one of the 22 unique family names and live on a Colony with the precise address. A control must be age (within 10 years) and sex-matched, live in the same or a contiguous postal code, and use the same medical practitioners. There were no interventions or identification of any member of the study. Mumps, acute coryza, and rubella are of the same frequency among the two groups. Only herpes simplex and cellulitis are more common among the Hutterites. All of the other nine common infectious diseases are significantly more common among the controls. The VZV diseases are not exclusively less common among the Hutterite Brethren. Nine other common infectious diseases are also less common but the degree of significant difference does not reach the level of the VZV diseases. The reduction in numbers of these diseases among the Hutterites is not related to the vaccination habits of the group and is not due to physical isolation. The Hutterites appear to have a more effective immune system relative to their neighbors.

The varicella zoster virus: a pilot trial of a potential therapeutic agent in multiple sclerosis

There are a number of similarities in the geographic, latitudinal, and epidemiological features of multiple sclerosis (MS) and varicella (V). In the experimental model of MS, repeated high antigen doses (myelin basic protein) have deleted both the clinical and pathological manifestations of the disease. Therefore, it seemed appropriate to explore the effects of varicella zoster vaccine on patients with MS. Fifty patients with chronic progressive MS were vaccinated with attenuated varicella virus vaccine and followed for one year. Fourteen patients improved, four became worse, and twenty-nine were unchanged. All patients were seropositive for varicella before vaccination and all had a rise in varicella antibodies after the vaccinations. There were no major untoward results from the vaccine. Four patients developed mild chicken-pox after vaccination. This was a short-term pilot trial without control subjects. Thus, the apparently favourable clinical and magnetic imaging changes must be assessed with caution, as must the lack of adverse effects.