Antibiotic use and risk of multiple sclerosis

From Animal Models to Clinical Trials: The Potential of Antimicrobials in Multiple Sclerosis Treatment

Multiple sclerosis (MS) is a chronic, autoimmune, demyelinating disease of the central nervous system (CNS). Microbes, including bacteria and certain viruses, particularly Epstein-Barr virus (EBV), have been linked to the pathogenesis of MS. While there is currently no cure for MS, antibiotics and antivirals have been studied as potential treatment options due to their immunomodulatory ability that results in the regulation of the immune process. The current issue addressed in this systematic review is the effect of antimicrobials, including antibiotics, antivirals, and antiparasitic agents in animals and humans. We performed a comprehensive search of PubMed, Google Scholar, and Scopus for articles on antimicrobials in experimental autoimmune encephalomyelitis animal models of MS, as well as in people with MS (pwMS). In animal models, antibiotics tested included beta-lactams, minocycline, rapamycin, macrolides, and doxycycline. Antivirals included acyclovir, valacyclovir, and ganciclovir. Hydroxychloroquine was the only antiparasitic that was tested. In pwMS, we identified a total of 24 studies, 17 of them relevant to antibiotics, 6 to antivirals, and 1 relevant to antiparasitic hydroxychloroquine. While the effect of antimicrobials in animal models was promising, only minocycline and hydroxychloroquine improved outcome measures in pwMS. No favorable effect of the antivirals in humans has been observed yet. The number and size of clinical trials testing antimicrobials have been limited. Large, multicenter, well-designed studies are needed to further evaluate the effect of antimicrobials in MS.

Exposure to systemic antibiotics in outpatient care and the risk of multiple sclerosis

BACKGROUND

Infections, early life exposures and the microbiome have been associated with the aetiology of multiple sclerosis (MS). Data on any possible roles of antibiotics is scarce and conflicting.

OBJECTIVE

The objective of this study was to investigate associations between outpatient systemic antibiotic exposure and the risk of MS in a nationwide case-control setting.

METHODS

Patients with MS were identified from the nation MS registry and their exposure to antibiotics was compared with that of persons without MS, provided by the national census authority. Antibiotic exposure was investigated using the national prescription database and analyzed by Anatomical Therapeutic Chemical (ATC) category.

RESULTS

Among the 1830 patients with MS and 12765 control persons, there were no associations between exposure to antibiotics in childhood (5-9 years) or adolescence (10-19 years) and the subsequent risk of MS. There was also no association between antibiotic exposure 1-6 years before disease onset and the risk of MS, save for exposure to fluoroquinolones in women (odds ratio: 1.28; 95% confidence interval: 1.03, 1.60; p = 0.028) which is probably associated with the increased infection burden in the MS prodrome.

CONCLUSION

Use of systemic prescription antibiotics was not associated with subsequent MS risk.

Relationship between medical history and multiple sclerosis: A-case-control study

This project sought to explore the potential association between medical history and the development of multiple sclerosis (MS) by conducting a retrospective study. This population-based case-control study included 200 MS cases and 2 control groups of 200 patients and healthy individuals each. Data was collected through face-to-face interviews, medical file reviews, and an electronic checklist. Multivariable analysis was used to calculate odds ratios and 95% confidence intervals to estimate the risk of each medical history on MS occurrences. Of 600 participants, 381 (63.5%) individuals were female. The mean age of the participants was 36.5 ± 11.9 years. The adjusted risks of MS were 4.40; 95% CI: 1.73 to 11.1 for measles and 4.75; 95% CI: 2.05 to 11 for amoxicillin consumption. The adjusted MS odds for autoimmune disease including 4.63; 95% CI: 0.35 to 60.6 for psoriasis and 7.15; 95% CI: 1.87 to 27.2 for myasthenia gravis. On the other hand, the calculated adjusted odds of MS occurrence were 0.14; 95% CI: 0.03 to 0.69 for seizure and 0.17; 95% CI: 0.02 to 1.49 for epilepsy. This study suggested that individuals with autoimmune diseases should be monitored more closely, as they may be at an increased risk of developing other autoimmune conditions, particularly MS.

Antibiotic use and multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Epidemiological studies have shown conflicting results between antibiotic use and multiple sclerosis (MS) risks. The present systematic review and meta-analysis were conducted to assess the association between antibiotic use and the risk of MS.

METHODS

PubMed, Scopus, Embase, Web of Science, and Google Scholar as well as reference lists of retrieved studies were searched systematically to identify studies were assessed the relationship between antibiotic use and MS up to September 24, 2022. Random-effects model was used for the calculation of pooled Odds ratio (OR) and 95% confidence intervals (CI).

RESULTS

Five independent studies containing 47,491 participants were included in the meta-analysis. The overall results of included studies showed a non-significant positive association between antibiotic use (OR overall=1.01, 95%CI: 0.75-1.37) and a non-significant negative association between penicillin use (OR overall= 0.83; 95%CI: 0.62-1.13) and MS risk. Heterogeneity was (I²=90.1, P _{heterogeneity} < 0.001) and (I²=90.7, P _{heterogeneity} < 0.001) in antibiotics and penicillin use groups respectively.

CONCLUSION

Our meta-analysis did not show a significant association between antibiotic or penicillin use with the risk of MS. However, due to the limitations of this study, further well-designed studies are required to confirm our findings.

Dietary Polyphenols, Microbiome, and Multiple Sclerosis: From Molecular Anti-Inflammatory and Neuroprotective Mechanisms to Clinical Evidence

Multiple sclerosis (MS) is a multifactorial, immune-mediated disease caused by complex gene-environment interactions. Dietary factors modulating the inflammatory status through the control of the metabolic and inflammatory pathways and the composition of commensal gut microbiota, are among the main environmental factors involved in the pathogenesis of MS. There is no etiological therapy for MS and the drugs currently used, often accompanied by major side effects, are represented by immunomodulatory substances capable of modifying the course of the disease. For this reason, nowadays, more attention is paid to alternative therapies with natural substances with anti-inflammatory and antioxidant effects, as adjuvants of classical therapies. Among natural substances with beneficial effects on human health, polyphenols are assuming an increasing interest due to their powerful antioxidant, anti-inflammatory, and neuroprotective effects. Beneficial properties of polyphenols on the CNS are achieved through direct effects depending on their ability to cross the blood-brain barrier and indirect effects exerted in part via interaction with the microbiota. The aim of this review is to examine the literature about the molecular mechanism underlying the protective effects of polyphenols in MS achieved by experiments conducted in vitro and in animal models of the disease. Significant data have been accumulated for resveratrol, curcumin, luteolin, quercetin, and hydroxytyrosol, and therefore we will focus on the results obtained with these polyphenols. Clinical evidence for the use of polyphenols as adjuvant therapy in MS is restricted to a smaller number of substances, mainly curcumin and epigallocatechin gallate. In the last part of the review, a clinical trial studying the effects of these polyphenols in MS patients will also be revised.

Advantages and limitations of experimental autoimmune encephalomyelitis in breaking down the role of the gut microbiome in multiple sclerosis

Since the first model of experimental autoimmune encephalomyelitis (EAE) was introduced almost a century ago, there has been an ongoing scientific debate about the risks and benefits of using EAE as a model of multiple sclerosis (MS). While there are notable limitations of translating EAE studies directly to human patients, EAE continues to be the most widely used model of MS, and EAE studies have contributed to multiple key breakthroughs in our understanding of MS pathogenesis and discovery of MS therapeutics. In addition, insights from EAE have led to a better understanding of modifiable environmental factors that can influence MS initiation and progression. In this review, we discuss how MS patient and EAE studies compare in our learning about the role of gut microbiome, diet, alcohol, probiotics, antibiotics, and fecal microbiome transplant in neuroinflammation. Ultimately, the combination of rigorous EAE animal studies, novel bioinformatic approaches, use of human cell lines, and implementation of well-powered, age- and sex-matched randomized controlled MS patient trials will be essential for improving MS patient outcomes and developing novel MS therapeutics to prevent and revert MS disease progression.

Antibiotic Use and Risk of Multiple Sclerosis: A Nested Case-Control Study in Emilia-Romagna Region, Italy

INTRODUCTION

Known risk factors for multiple sclerosis (MS) include smoking, a low vitamin D status, obesity, and EBV, while the inflammatory feature of the disease strongly suggests the presence of additional infectious agents. The association between use of antibiotics and MS risk that could shed light on these factors is still undetermined. We aimed to evaluate the association between antibiotics and MS risk, in the Emilia-Romagna region (RER), Italy.

METHODS

All adult patients with MS seen at any RER MS center (2015-2017) were eligible. For each of the 877 patients included, clinical information was collected and matched to 5 controls (RER residents) (n = 4,205) based on age, sex, place of residence, and index year. Information on antibiotic prescription was obtained through the linkage with the RER drug prescription database.

RESULTS

Exposure to any antibiotic 3 years prior to the index year was associated with an increased MS risk (OR = 1.52; 95% CI = 1.29-1.79). Similar results were found for different classes. No dose-response effect was found.

DISCUSSION/CONCLUSIONS

Our results suggest an association between the use of antibiotics and MS risk in RER population. However, further epidemiological studies should be done with information on early life and lifestyle factors.

Dominant Antibiotic Consumption Patterns Might Be Associated With the Prevalence of Multiple Sclerosis in European Countries

BACKGROUND/AIM

With a prevalence of 50-300 per 100,000 people, about 2.3 million people are estimated to live with multiple sclerosis (MS) globally. The role of antibiotics in the development, or prevention of MS is controversial. We aimed to elucidate the association between antibiotic consumption and MS.

PATIENTS AND METHODS

Pearson statistical comparisons were performed between the annual average antibiotic consumption patterns expressed in Defined Daily Dose/1,000 inhabitants/Day of the antibiotic consumption for the years of 1997-2018 in 30 European countries, with the respective prevalence of MS estimated for 2016.

RESULTS

A positive correlation (promoting effect) has been observed between narrow spectrum penicillin (r=0.636) and tetracycline (r=0.412) consumption with MS prevalence.

CONCLUSION

Countries, with high consumption of narrow spectrum penicillin and tetracycline, experience a higher prevalence of MS than other countries.

Infections in patients diagnosed with multiple sclerosis: A multi-database study

BACKGROUND

Recent data on the rates of infections among patients with multiple sclerosis (MS) are sparse. The objective of this study was to quantify incidence of infections in patients with MS compared with a matched sample of patients without MS (non-MS).

METHODS

This study was conducted in two separate electronic medical databases: the United States Department of Defense (US-DOD) military health care system and the United Kingdom's Clinical Practice Research Datalink GOLD (UK-CPRD). We identified patients with a first recorded diagnosis of MS between 2001 and 2016 (UK-CPRD) or 2004 and 2017 (US-DOD) and matched non-MS patients. We identified infections recorded after the MS diagnosis date (or the matched date in non-MS patients) and calculated incidence rates (IRs) and incidence rate ratios (IRRs) with 95% confidence intervals (CIs) by infection site and type.

RESULTS

Relative to non-MS patients, MS patients had higher rates of any infection (US-DOD IRR 1.76; 95% CI 1.72-1.80 and UK-CPRD IRR 1.25; 95% CI 1.21-1.29) and a two-fold higher rate of hospitalized infections (US-DOD IRR 2.43; 95% CI 2.23-2.63 and UK-CPRD IRR 2.00; 95% CI 1.84-2.17). IRs of any infection were higher in females compared with males in both MS and non-MS patients, while IRs of hospitalized infections were similar between sexes in both MS and non-MS patients. The IR of first urinary tract or kidney infection was nearly two-fold higher in MS compared with non-MS patients (US-DOD IRR 1.88; 95% CI 1.81-1.95 and UK-CPRD IRR 1.97; 95% CI 1.86-2.09) with higher rates in females compared with males. IRs for any opportunistic infection, candidiasis and any herpes virus were increased between 20 and 52% among MS patients compared with non-MS patients. IRs of meningitis, tuberculosis, hepatitis B and C were all low.

CONCLUSION

MS patients have an increased risk of infection, notably infections of the renal tract, and a two-fold increased risk of hospitalized infections compared with non-MS patients.

Infections, Vaccines and Autoimmunity: A Multiple Sclerosis Perspective

Background: Multiple sclerosis (MS) is a chronic neuroinflammatory and neurodegenerative disease that is associated with multiple environmental factors. Among suspected susceptibility events, studies have questioned the potential role of overt viral and bacterial infections, including the Epstein Bar virus (EBV) and human endogenous retroviruses (HERV). Furthermore, the fast development of immunomodulatory therapies further questions the efficacy of the standard immunization policies in MS patients. Topics reviewed: This narrative review will discuss the potential interplay between viral and bacterial infections and their treatment on MS susceptibility and disease progression. In addition, the review specifically discusses the interactions between MS pathophysiology and vaccination for hepatitis B, influenza, human papillomavirus, diphtheria, pertussis, and tetanus (DTP), and Bacillus Calmette-Guerin (BCG). Data regarding potential interaction between MS disease modifying treatment (DMT) and vaccine effectiveness is also reviewed. Moreover, HERV-targeted therapies such as GNbAC1 (temelimab), EBV-based vaccines for treatment of MS, and the current state regarding the development of T-cell and DNA vaccination are discussed. Lastly, a reviewing commentary on the recent 2019 American Academy of Neurology (AAN) practice recommendations regarding immunization and vaccine-preventable infections in the settings of MS is provided. Conclusion: There is currently no sufficient evidence to support associations between standard vaccination policies and increased risk of MS. MS patients treated with immunomodulatory therapies may have a lower benefit from viral and bacterial vaccination. Despite their historical underperformance, new efforts in creating MS-based vaccines are currently ongoing. MS vaccination programs follow the set back and slow recovery which is widely seen in other fields of medicine.

Chronic Inflammatory Diseases at Secondary Sites Ensuing Urogenital or Pulmonary Chlamydia Infections

Chlamydia trachomatis and C. pneumoniae are members of the Chlamydiaceae family of obligate intracellular bacteria. The former causes diseases predominantly at the mucosal epithelial layer of the urogenital or eye, leading to pelvic inflammatory diseases or blindness; while the latter is a major causative agent for pulmonary infection. On top of these well-described diseases at the respective primary infection sites, Chlamydia are notoriously known to migrate and cause pathologies at remote sites of a host. One such example is the sexually acquired reactive arthritis that often occurs at few weeks after genital C. trachomatis infection. C. pneumoniae, on the other hand, has been implicated in an extensive list of chronic inflammatory diseases which include atherosclerosis, multiple sclerosis, Alzheimer’s disease, asthma, and primary biliary cirrhosis. This review summarizes the Chlamydia infection associated diseases at the secondary sites of infection, and describes the potential mechanisms involved in the disease migration and pathogenesis.

The Beneficial and Debilitating Effects of Environmental and Microbial Toxins, Drugs, Organic Solvents and Heavy Metals on the Onset and Progression of Multiple Sclerosis

Multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system is common amongst young adults, leading to major personal and socioeconomic burdens. However, it is still considered complex and challenging to understand and treat, in spite of the efforts made to explain its etiopathology. Despite the discovery of many genetic and environmental factors that might be related to its etiology, no clear answer was found about the causes of the illness and neither about the detailed mechanism of these environmental triggers that make individuals susceptible to MS. In this review, we will attempt to explore the major contributors to MS autoimmunity including genetic, epigenetic and ecological factors with a particular focus on toxins, chemicals or drugs that may trigger, modify or prevent MS disease.

Multi-database study of multiple sclerosis: identification, validation and description of MS patients in two countries

Objective

To describe the resources and methods used to identify and validate multiple sclerosis (MS) and match non-MS patients in each of the two databases, and to characterize their demographics, comorbidities and concomitant medications.

Methods

This study was conducted in two separate electronic medical databases, the United States Department of Defense (DOD) military health care system and the United Kingdom’s Clinical Practice Research Datalink (CPRD) GOLD. We identified patients with a first recorded diagnosis of MS in 2001–2016 (CPRD) or 2004–2017 (DOD) and matched non-MS patients using algorithms appropriate to each database. We describe patient symptoms, comorbidities, and medication use at the time of the MS diagnosis and compared them to the non-MS cohort.

Results

We identified 8695 patients with MS and 86,934 matched non-MS patients in the DOD database and 6932 patients with MS and 68,526 matched non-MS patients in CPRD GOLD. Most MS patients were female (around 70%) and were diagnosed before age 60 (88%). MS patients had higher prevalence of depression and other psychiatric conditions at MS diagnosis compared to non-MS patients. Epilepsy, fractures and infections were also more common. MS patients had many expected symptoms and treatments documented in their records prior to the MS diagnosis.

Conclusion

These results are consistent between the two databases, as well as with previous studies of MS. Future analyses of these patients’ experience after MS diagnosis will provide valuable insights into disease and treatment patterns in relation to risk of chronic diseases and mortality.

Antibiotics and autoimmune and allergy diseases: Causative factor or treatment?

The newborn infant emerges from an almost sterile environment into a world of bacteria. Bacteria colonize the infant's skin, lungs, and, of most importance, the gut. The process of bacterial colonization is coordinated, and each body niche acquires a unique composition of bacteria. In the gut, most bacteria belong to the Firmicutes and Bacteroidetes phyla, while Actinobacteria and Proteobacteria are far less abundant. Some of these bacteria possess strong immunoregulatory properties. Bacterial colonization is essential to skew the newborn's immune response away from the allergy-favoring Type-2 response towards a Type-1 immune response, which is essential for pathogen elimination. Imbalance between Type 1 and Type 2 responses, however, can promote autoimmunity. In addition, the microbiota shapes immune responses in adults. Autoimmune and allergic diseases are commonly associated with an altered composition of resident bacteria, which is known as dysbiosis. Perhaps the most common cause of disruption and alteration of the bacterial colonization of newborns is the use of antibiotics. It is not known whether the dysbiosis precedes or is the consequence of allergic and autoimmune disorders, and whether antibiotics can be a trigger for these disorders, depending on the type of antibiotic used and the maturity of immune system. In this review, we discuss the development of the microbiota in different body niches and their immunomodulatory potential. We evaluate the impact of antibiotics, both in mice and in humans, on microbial communities and how that may impact the development and manifestation of diseases through all stages of life: the prenatal period, childhood, and adulthood.

Infectious exposure, antibiotic use, and multiple sclerosis: A population-based incident case-control study

BACKGROUND

The existing reports regarding the potential role of infections as well as antibiotic use in multiple sclerosis (MS) etiology are inconclusive.

OBJECTIVES

We aimed to investigate the association of viral infections as well as antibiotic use and the risk of developing MS.

MATERIALS & METHODS

This was a population-based incident case-control study of 547 incident cases and 1057 general population controls obtained from 22 municipality areas of Tehran (7/8/2013-17/2/2015). Multiple logistic regression models were used to determine the adjusted associations.

RESULTS

Overall antibiotic use for ≥14 days during 3 years before the index date, significantly decreased the odds of MS OR 0.69 (95%CI: 0.53-0.91, P = .008). The results were consistent for different types of antibiotics, including penicillin OR 0.50 (95%CI: 0.34-0.75, P = .001) and cephalosporins OR 0.25 (95%CI: 0.12-0.50, P < .001). History of IM was associated with a more than 5fold increased risk of MS OR = 5.7 (95%CI, 1.28-25.37). There was no statistically significant association between any other single or cumulative number of viral infections with subsequent risk of MS (P > .05).

CONCLUSIONS

Considering the possibility of reverse causation, the results of this large case-control study suggest that use of antibiotics may be associated with a decreased risk of MS. However, viral disease other than infectious mononucleosis was not associated with MS risk.

Infections seem to be more frequent before onset of pediatric multiple sclerosis: A Danish nationwide nested case–control study

Background:

Infections are suspected environmental triggers for multiple sclerosis (MS). The relationship between the timing and cumulative number of childhood infections regarding pediatric MS risk is uninvestigated.

Objectives:

To investigate whether childhood infections contribute to pediatric MS.

Methods:

A nationwide nested case–control study with detailed MS case ascertainment including chart review was undertaken. For each MS case, we selected five control children using density sampling from the entire Danish population, matching controls to children with MS by sex and birthdate. We analyzed data with the cumulative number of childhood infections as exposure and MS as outcome. Hazard ratios (HRs) including 95% confidence intervals (CIs) were estimated using Cox regression.

Results:

We identified 212 children with MS and 1,060 controls. Median age at MS onset was 15.3 years (range: 7.6–17.8 years); 72% were girls. Each infection during the preceding 3 years increased the hazard for MS by 11% (95% CI = 1.01–1.22, p = 0.04); having 5+ infections compared with 0–4 infections in the preceding 3 years doubled the hazard for MS (HR: 2.18; 95% CI = 1.12–4.30, p = 0.02).

Conclusion:

Children with MS appeared to have more infections in the 3 years preceding MS clinical onset; accordingly, immune response to infections may influence MS pathogenesis.

Microbiota Signaling Pathways that Influence Neurologic Disease

Though seemingly distinct and autonomous, emerging evidence suggests there is a bidirectional interaction between the intestinal microbiota and the brain. This crosstalk may play a substantial role in neurologic diseases, including anxiety, depression, autism, multiple sclerosis, Parkinson's disease, and, potentially, Alzheimer's disease. Long hypothesized by Metchnikoff and others well over 100 years ago, investigations into the mind-microbe axis is now seeing a rapid resurgence of research. If specific pathways and mechanisms of interaction are understood, it could have broad therapeutic potential, as the microbiome is environmentally acquired and can be modified to promote health. This review will discuss immune, endocrine, and neural system pathways that interconnect the gut microbiota to central nervous system and discuss how these findings might be applied to neurologic disease.

Drug exposure and the risk of multiple sclerosis: A systematic review

BACKGROUND

Several environmental and lifestyle factors have been associated with multiple sclerosis (MS) risk, including some pharmacological treatments. We systematically reviewed the literature on prescription drug exposure and MS risk.

METHODS

Six databases were searched for original observational studies reporting drug exposure and MS risk published before 2017.

RESULTS

Thirteen articles fulfilled inclusion criteria. Exposure to neither amiloride nor valproic acid was associated with MS (adjusted hazard ratio (adj.HR = 1.34;95% CI:0.81-2.20; adj.HR = 1.30;95%CI:0.44-3.80, respectively). Four studies explored oral contraceptive exposure and reported no association with MS; while a single study found an increased risk (odds ratio [adj.OR] = 1.52;95%CI:1.21-1.91). While penicillin exposure was associated with reduced risk of developing MS (adj.OR = 0.5;95%CI:0.3-0.9), a later study observed an elevated risk for penicillin (adj.OR = 1.21;95%CI:1.10-1.27) and all antibiotics (adj.OR = 1.41;95%CI:1.29-1.53), which was potentially attributed to underlying infection. Anti-tumor necrosis factor-alpha (TNFα) was not associated with MS risk in persons with inflammatory bowel disease (standard morbidity ratio = 4.2;95%CI:0.1-23.0) and arthritis (standardized incidence ratio = 1.38;95%CI:0.69-2.77); however, men exposed to anti-TNFα who also had arthritis and individuals with ankylosing spondylitis were at an increased risk (standardized incidence ratios = 3.91;95%CI:1.47-10.42 and 3.48;95%CI:1.45-8.37, respectively). A reduced risk of MS was observed with exposure to the beta2-adrenergic agonist fenoterol (adj.OR = 0.58;95%CI:0.45-0.76), and the sedating histamine 1-receptor antagonists (adj.OR = 0.2;95%CI:0.1-0.8), but not the non-sedating equivalent (adj.OR = 0.8;95%CI:0.4-1.6).

CONCLUSIONS

The suggestion that some drugs may prevent MS is intriguing and warrants further study. In addition, further pharmacovigilance is needed to assess the safety of anti-TNFα drugs in specific populations in the context of MS risk.

The hygiene hypothesis in autoimmunity: the role of pathogens and commensals

The incidence of autoimmune diseases has been steadily rising. Concomitantly, the incidence of most infectious diseases has declined. This observation gave rise to the hygiene hypothesis, which postulates that a reduction in the frequency of infections contributes directly to the increase in the frequency of autoimmune and allergic diseases. This hypothesis is supported by robust epidemiological data, but the underlying mechanisms are unclear. Pathogens are known to be important, as autoimmune disease is prevented in various experimental models by infection with different bacteria, viruses and parasites. Gut commensal bacteria also play an important role: dysbiosis of the gut flora is observed in patients with autoimmune diseases, although the causal relationship with the occurrence of autoimmune diseases has not been established. Both pathogens and commensals act by stimulating immunoregulatory pathways. Here, I discuss the importance of innate immune receptors, in particular Toll-like receptors, in mediating the protective effect of pathogens and commensals on autoimmunity.

Allergies, antibiotics use, and multiple sclerosis

BACKGROUND

The associations between allergies, antibiotics use, and multiple sclerosis (MS) remain controversial and their mediating or moderating effects have not yet been examined. We aimed to assess the direct and indirect influences of allergies and antibiotics use on MS development, and their interactions.

METHODS

A 1:3 matched case-control study was performed using the National Ambulatory Medical Care Survey database from 2006 to 2013 in the USA. Multiple sclerosis was identified based on the ICD-9 code (340.0) in any position. Cases were matched to their controls based on survey year, age, gender, race, payer type, region, and tobacco use. Allergy diseases and antibiotics prescriptions were extracted by ICD-9 code and drug classification code, respectively. Both generalized structural equation model and MacArthur approach were used to examine their intrinsic relationships.

RESULTS

The weighted prevalence of MS was 133.7 per 100,000 visits. A total of 829 MS patients and 2441 controls were matched. Both respiratory tract allergies (OR = 0.29, 95% CI: 0.18, 0.49) and other allergies (OR = 0.38, 95% CI: 0.19, 0.77) were associated with a reduction of the risk of MS. Patients with respiratory tract allergies were more likely to use penicillin (OR = 8.73, 95% CI: 4.12, 18.53) and other antibiotics (OR = 3.77, 95% CI: 2.72, 5.21), and those with other allergies had a higher likelihood of penicillin use (OR = 4.15, 95% CI: 1.27, 13.54); however, the link between antibiotics use and MS was not confirmed although penicillin use might mediate the relationship between allergies and MS.

CONCLUSIONS

The findings supported allergy as a protective factor for MS development. We also suggest antibiotics use might not be a suitable indicator of bacterial infection to investigate the cause of MS.

The gut-brain connection: triggering of brain autoimmune disease by commensal gut bacteria

In a transgenic model of spontaneous experimental autoimmune encephalomyelitis, autoimmune attack against the CNS requires the presence of an intact commensal gut flora. Extending this observation to human autoimmune disease, such as multiple sclerosis, we postulate that the pathogenic reaction requires the coincidence of at least three factors: a permissive genetic disposition, a pro-inflammatory intestinal microbial profile, and the accumulation of autoreactive T cells in the gut-associated lymphatic tissue. This concept may offer new approaches to diagnostic markers and non-invasive therapies.

Factors associated with onset, relapses or progression in multiple sclerosis: A systematic review

Multiple sclerosis (MS) is a chronic disease of the central nervous system with an unidentified etiology. We systematically reviewed the literature on the possible risk factors associated with MS disease onset, relapses and progression from 1960 to 2012 by accessing six databases and including relevant systematic reviews, meta-analyses, case-control or cohort studies. The focus was on identifying modifiable risk factors. Fifteen systematic reviews and 169 original articles were quality assessed and integrated into a descriptive review. Best evidence, which included one or more prospective studies, suggested that lower exposure to sunlight and/or lower serum vitamin D levels were associated with an increased risk of developing MS onset and subsequent relapses, but a similar quality of evidence was lacking for disease progression. Prospective studies indicated that cigarette smoking may increase the risk of MS as well as accelerate disease progression, but whether smoking altered the risk of a relapse was largely unknown. Infections were implicated in both risk of developing MS and relapses, but data for progression were lacking. Specifically, exposure to the Epstein-Barr virus, particularly if this manifested as infectious mononucleosis during adolescence, was associated with increased MS risk. Upper respiratory tract infections were most commonly associated with an increase in relapses. Relapse rates typically dropped during pregnancy, but there was no strong evidence to suggest that pregnancy itself altered the risk of MS or affected long-term progression. Emerging research with the greatest potential to impact public health was the suggestion that obesity during adolescence may increase the risk of MS; if confirmed, this would be of major significance.

Epidemiology of multiple sclerosis: results from a large observational study in the UK

Multiple sclerosis (MS) progression to mortality may not be solely determined by the underlying autoimmune process. We conducted a study in a large cohort of MS patients with the aim of describing characteristics of MS patients and identification of predictors for all-cause mortality in this patient group. We performed a retrospective analysis of primary care data from the UK Clinical Practice Research Datalink. Incident MS cases diagnosed between 1993 and 2006 were identified and validated using electronic and original medical records. Patients were followed to identify deaths; hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional regression with age as time-scale. In total, 1713 incident MS cases were identified. Following MS diagnosis, frequent comorbidities were infections (80%), and depression (46%). Adjusted HRs (95% CIs) for all-cause mortality were: 2.0 (1.2-3.4) for current smoking; 7.6 (3.2-17.7) for alcohol abuse; 2.7 (1.6-4.5) for pneumonia and influenza; 4.1 (2.7-6.3) for urinary tract infections; 2.2 (1.2-4.2) for heart disease and 4.9 (2.9-8.0) for cancer. Our results suggest that MS survival is influenced not only by the underlying autoimmune process, but also by patient comorbidities and lifestyle factors.

Risk factors associated with the onset of relapsing-remitting and primary progressive multiple sclerosis: a systematic review

Multiple sclerosis (MS) is a chronic central nervous system disease with a highly heterogeneous course. The aetiology of MS is not well understood but is likely a combination of both genetic and environmental factors. Approximately 85% of patients present with relapsing-remitting MS (RRMS), while 10–15% present with primary progressive MS (PPMS). PPMS is associated with an older onset age, a different sex ratio, and a considerably more rapid disease progression relative to RRMS. We systematically reviewed the literature to identify modifiable risk factors that may be associated with these different clinical courses. We performed a search of six databases and integrated twenty observational studies into a descriptive review. Exposure to Epstein-Barr virus (EBV) appeared to increase the risk of RRMS, but its association with PPMS was less clear. Other infections, such as human herpesvirus-6 and chlamydia pneumoniae, were not consistently associated with a specific disease course nor was cigarette smoking. Despite the vast literature examining risk factors for the development of MS, relatively few studies reported findings by disease course. This review exposes a gap in our understanding of the risk factors associated with the onset of PPMS, our current knowledge being predominated by relapsing-onset MS.

Mortality of patients with multiple sclerosis: a cohort study in UK primary care

We aimed to estimate rates, causes and risk factors of all-cause mortality in a large population-based cohort of multiple sclerosis (MS) patients compared with patients without MS. Using data from the UK General Practice Research Database, we identified MS cases diagnosed during 2001–2006 and validated using patients’ original records where possible. We also included MS cases during 1993–2000 identified and validated in an earlier study. Cases were matched to up to ten referents without MS by age, sex, index date (date of first MS diagnosis for cases and equivalent reference date for controls), general practice and length of medical history before first MS diagnosis. Patients were followed up to identify deaths; hazard ratios (HRs) and 95 % confidence intervals (CIs) were estimated using Cox-proportional regression. MS patients (N = 1,822) had a significantly increased risk of all-cause mortality compared with referents (N = 18,211); adjusted HR 1.7 (95 % CI 1.4–2.1). Compared with referents, female MS patients had a higher but not significantly different HR for death than males; adjusted HR 1.86 (95 % CI 1.46–2.38) vs. HR 1.31 (95 % CI 0.93–1.84), respectively. The most commonly recorded cause of death in MS patients was ‘MS’ (41 %), with a higher proportion recorded among younger patients. A significantly higher proportion of referents than MS patients had cancer recorded as cause of death (40 vs. 19 %). Patients with MS have a significant 1.7-fold increased risk of all-cause mortality compared with the general population. MS is the most commonly recorded cause of death among MS patients.

Is a hypothetical melanoma-like neuromelanin the underlying factor essential for the aetiopathogenesis and clinical manifestations of multiple sclerosis?

Background

Multiple sclerosis (MS) has undergone a significant increase in incidence in the industrialised nations over the last 130 years. Changing environmental factors, possibly infections or a lack of or altered timing of them, determine the prevalence of the disease. Although a plethora of aetiological factors, clearly evident in a group of children with MS, appear relevant, there may nevertheless be a single factor essential for the aetiopathogenesis and clinical manifestation of MS.

Description and discussion

This hitherto unknown factor is postulated to be a ‘melanoma-like neuromelanin’ (MLN) dependent on the activation of a gene for syncytin-1. An involvement of MLN could explain the diverse findings in the epidemiology, immunology and pathology of MS, requiring a consideration of a complex infectious background, the human leucocyte antigens, as well as cosmic radiation causing geomagnetic disturbances, vitamin D deficiency, smoking, and lower levels of uric acid.

Summary

In principle, the MLN-based concept is a unifying one, capable of explaining a number of characteristics of the disease. To date, MLN has not been addressed in studies on MS and future work will need to be done on human patients, as there is little or no neuromelanin (the precursor of MLN) in the animals used as experimental models in the study of MS.

Intrauterine environment and multiple sclerosis: a population- based case-control study

BACKGROUND

Associations of several autoimmune disorders with intrauterine and early life exposures have been reported.

OBJECTIVE

We used population-based linked hospital discharge-birth records data to explore maternal, prenatal, and infant characteristics in relation to MS-related hospitalization among Washington State residents.

METHODS

272 cases hospitalized for MS during 1988-2008 and 2720 birth record controls were identified from linked hospital discharge-birth certificate data. Exposure information from their birth records were compared in a population-based case-control study to estimate adjusted odds ratios (ORs) and 95% confidence intervals (95%CIs) for associations with MS hospitalization.

RESULTS

Most factors examined were not associated with MS. Having a mother with 3+ prior live births (OR 0.54, 95%CI 0.31-0.95) or having 3+ older siblings (OR 0.49, 95%CI 0.28-0.85) were negatively associated. Maternal prenatal smoking (OR 3.09, 95%CI 1.22-7.84) was positively associated.

CONCLUSION

Transplacental exposure to smoke constituents including chemicals affecting myelin may help explain any association with maternal prenatal smoking; however, we were unable to assess childhood or adult smoke exposures which may also account at least partly for this effect. The negative associations observed with greater maternal parity and number of siblings are consistent with some other studies. Reasons for these associations may involve various pathways.

Use of penicillin and other antibiotics and risk of multiple sclerosis: a population-based case-control study

A 2006 study from the United Kingdom found that penicillin use may decrease the risk of multiple sclerosis (MS). To confirm this finding, the authors conducted a nationwide case-control study in Denmark, using the Danish Multiple Sclerosis Registry to identify 3,259 patients with MS onset from 1996 to 2008, and selected 10 population controls per case (n = 32,590), matched on sex and age. Through the National Prescription Database, prescriptions for antibiotics redeemed from 1995 to 2008 and before the date of first MS symptom/index date were identified. Conditional logistic regression analysis was used to compute odds ratios associating antibiotic use with MS occurrence. In total, 1,922 patients (59%) redeemed penicillin prescriptions before the index date and 2,292 (70%) redeemed any type of antibiotic prescription. Penicillin use was associated with an increased risk of MS (odds ratio = 1.21, 95% confidence interval: 1.10, 1.27). Use of any type of antibiotic was similarly associated with an increased risk of MS (odds ratio = 1.41, 95% confidence interval: 1.29, 1.53). The odds ratios for different types of antibiotics ranged between 1.08 and 1.83. Thus, this study found that penicillin use and use of other antibiotics were similarly associated with increased risk of MS, suggesting that the underlying infections may be causally associated with MS.

Using your electronic medical record for research: a primer for avoiding pitfalls

In Canada, use of electronic medical records (EMRs) among primary health care (PHC) providers is relatively low. However, it appears that EMRs will eventually become more ubiquitous in PHC. This represents an important development in the use of health care information technology as well as a potential new source of PHC data for research. However, care in the use of EMR data is required. Four years ago, researchers at the Centre for Studies in Family Medicine, The University of Western Ontario created an EMR-based research project, called Deliver Primary Health Care Information. Implementing this project led us to two conclusions about using PHC EMR data for research: first, additional time is required for providers to undertake EMR training and to standardize the way data are entered into the EMR and second, EMRs are designed for clinical care, not research. Based on these experiences, we offer our thoughts about how EMRs may, nonetheless, be used for research. Family physician researchers who intend to use EMR data to answer timely questions relevant to practice should evaluate the possible impact of the four questions raised by this paper: (i) why are EMR data different?; (ii) how do you extract data from an EMR?; (iii) where are the data stored? and (iv) what is the data quality? In addition, consideration needs to be given to the complexity of the research question since this can have an impact on how easily issues of using EMR data for research can be overcome.

Epidemiology of Multiple Sclerosis

This chapter discusses the environmental factors associated to epidemiology of multiple sclerosis. The epidemiologic evidence points to three environ­mental risk factors—infection with the Epstein-Barr virus (EBV), low levels of vitamin D, and cigarette smoking—whose association with multiple sclerosis (MS) seems to satisfy in varying degrees most of the criteria that support causality, including temporality, strength, consis­tency, biologic gradient, and plausibility. None of these associations, however, has been tested experimentally in humans and only one––vitamin D deficiency is presently amenable to experimental interventions. The evidence, albeit more sparse and inconsistent, linking other environmental factors to MS risk are summarized. Epidemiologic clues to the hypothetical role of infection in MS are com­plex and often seem to point in opposite directions. The ecological studies, database/linkage analyses, and longitudinal studies of sunlight exposure and vitamin D are reviewed. Biologic mechanisms for smoking and increased risk of MS could be neuro­toxic, immunomodulatory, vascular, or they could involve increased frequency and duration of respiratory infections. Some other possible risk factors include––diet and hepatitis B vaccine.

Lipid autoreactivity in multiple sclerosis

Lipids comprise over 70% of the myelin sheath but have been largely underinvestigated as autoantigens in multiple sclerosis (MS). This paper cites evidence for the involvement of lipid autoreactivity in MS and details how self lipid cross-reactivity may also contribute to the development of type 1 diabetes and autoimmune thyroid disorders (both of which have been associated with MS). A further analysis of myelin chemistry suggests several mechanisms by which infection may contribute to etiology and trigger lipid autoreactivity via molecular mimicry. This analysis may aid the development of new therapies for autoimmune diseases.

Hypothesized role of galactocerebroside and NKT cells in the etiology of multiple sclerosis

According to the molecular mimicry theory, multiple sclerosis (MS) develops when the immune system mistakenly attacks a component of the myelin sheath that is structurally similar to a foreign epitope. The glycolipid galactocerebroside (GalC) is a major component of myelin. As lipids comprise between 70% and 85% of myelin, glycolipids should be investigated as candidate autoantigens in MS. GalC displays broad structural similarities to the Borrelia burgdorferi glycolipid antigen BbGL-2 and to the Sphingomonas antigen GalAGSL. In principle, therefore, these bacteria may induce an autoimmune attack on the myelin sheath. GalC is also structurally similar to natural killer T (NKT) cell ligand alpha-galactosylceramide (alpha-GalCer). Further studies must be performed to clarify the role of GalC in the activation of NKT cells and the development of MS.

PCR for bacterial 16S ribosomal DNA in multiple sclerosis cerebrospinal fluid

The cause of multiple sclerosis (MS) is currently unknown. The hypothesis of this study is that MS is caused by a chronic bacterial infection of the central nervous system (CNS) and the ensuing immune response. We developed a sensitive two-stage polymerase chain reaction method using nested or semi-nested primers specific for the bacterial 16S ribosomal DNA to test for the presence of bacterial DNA in cerebrospinal fluid. We designed seven sets of primers to amplify DNA from spirochetes , Campylobacter, Mycoplasma, Chlamydia, Bartonella, Mycobacteria and Streptococcus and tested cerebrospinal fluid from patients with relapsing-remitting MS, primary progressive MS, transverse myelitis and controls. We did not detect DNA from any of the groups of bacteria in patients or controls. We conclude that we were unable to find evidence for CNS infection with any of these seven groups of bacteria in MS.

Environmental risk factors for multiple sclerosis. Part II: Noninfectious factors

As discussed in Part I of this review, the geographic distribution of multiple sclerosis (MS) and the change in risk among migrants provide compelling evidence for the existence of strong environmental determinants of MS, where "environmental" is broadly defined to include differences in diet and other behaviors. As we did for infections, we focus here primarily on those factors that may contribute to explain the geographic variations in MS prevalence and the change in risk among migrants. Among these, sunlight exposure emerges as being the most likely candidate. Because the effects of sun exposure may be mediated by vitamin D, we also examine the evidence linking vitamin D intake or status to MS risk. Furthermore, we review the evidence on cigarette smoking, which cannot explain the geographic variations in MS risk, but may contribute to the recently reported increases in the female/male ratio in MS incidence. Other proposed risk factors for MS are mentioned only briefly; although we recognize that some of these might be genuine, evidence is usually sparse and unpersuasive.