The human microbiome in multiple sclerosis: pathogenic or protective constituents?

Bacterial variation in the oral microbiota in multiple sclerosis patients

BACKGROUND

Microorganisms in oral cavity are called oral microbiota, while microbiome consists of total genome content of microorganisms in a host. Interaction between host and microorganisms is important in nervous system development and nervous diseases such as Autism, Alzheimer, Parkinson and Multiple Sclerosis (MS). Bacterial infections, as an environmental factor in MS pathogenesis play role in T helper 17(Th17) increase and it enhancing the production of pro-inflammatory cytokines such as Interlukin-21(IL-21), IL-17 and IL -22. Oral microbiota consists diverse populations of cultivable and uncultivable bacterial species. Denaturing gradient gel electrophoresis (DGGE) is an acceptable method for identification of uncultivable bacteria. In this study, we compared the bacterial population diversity in the oral cavity between MS and healthy people.

METHODS

From October to March 2019, samples were taken at Kermanshah University of Medical Sciences' MS patients center. A total of 30 samples were taken from MS patients and another 30 samples were taken from healthy people. Phenotypic tests were used to identify bacteria after pure cultures were obtained. DNA was extracted from 1 mL of saliva, and PCR products produced with primers were electrophoresed on polyacrylamide gels.

RESULTS

The genera Staphylococcus, Actinomyces, Fusobacterium, Bacteroides, Porphyromonas, Prevotella, Veillonella, Propionibacterium and uncultivable bacteria with accession number MW880919-25, JQ477416.1, KF074888.1 and several other un-culturable strains were significantly more abundant in the MS group while Lactobacillus and Peptostreptococcus were more prevalent in the normal healthy group according to logistic regression method.

CONCLUSION

Oral micro-organisms may alleviate or exacerbate inflammatory condition which impact MS disease pathogenesis. It may be assumed that controlling oral infections may result in reduction of MS disease progression.

Gut microbiome and chronic prostatitis/chronic pelvic pain syndrome

Analysis of the human microbiome continues to reveal new and previously unrealized associations between microbial dysbiosis and disease. Novel approaches to bacterial identification using culture-independent methods allow practitioners to discern the presence of alterations in the taxa and diversity of the microbiome and identify correlations with disease processes. While some of these diseases that have been extensively studied are well-defined in their etiology and treatment methods (colorectal cancer), others have provided much more significant challenges in both diagnosis and treatment. One such condition, chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), has several etiological and potentiating contributions from infection, inflammation, central nervous system (CNS) changes, stress, and central sensitization-all factors that play important roles in the crosstalk between the human body and its microbiome. No singular cause of CP/CPPS has been identified and it is most likely a syndrome with multifactorial causes. This heterogeneity and ambiguity are sources of significant frustration for patients and providers alike. Despite multiple attempts, treatment of chronic prostatitis with monotherapy has seen limited success, which is thought to be due to its heterogeneous nature. Phenotypic approaches to both classify the disease and direct treatment for CP/CPPS have proven beneficial in these patients, but questions still remain regarding etiology. Newer microbiome research has found correlations between symptom scores and disease severity and the degree of dysbiosis in urine and gut (stool) microbiomes in these patients as compared to un-afflicted controls. These findings present potential new diagnostic and therapeutic targets in CP/CPPS patients.

Role of pathogens in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating autoimmune disease of the central nervous system (CNS). Although the etiology of MS is unknown, genetic and environmental factors play a role. Infectious pathogens are the likely environmental factors involved in the development of MS. Pathogens associated with the development or exacerbation of MS include bacteria, such as Mycoplasma pneumoniae and Chlamydia pneumoniae, the Staphylococcus aureus-produced enterotoxins that function as superantigens, viruses of the herpes virus (Epstein-Barr virus and human herpesvirus 6) and human endogenous retrovirus (HERV) families and the protozoa Acanthamoeba castellanii. Evidence, from studies with humans and animal models, supporting the association of these various pathogens with the development and/or exacerbation of MS will be discussed along with the potential mechanisms including molecular mimicry, epitope spreading and bystander activation. In contrast, infection with certain parasites such as helminthes (Schistosoma mansoni, Fasciola hepatica, Hymenolepis nana, Trichuris trichiura, Ascaris lumbricoides, Strongyloides stercolaris, Enterobius vermicularis) appears to protect against the development or exacerbation of MS. Evidence supporting the ability of parasitic infections to protect against disease will be discussed along with a brief summary of a recent Phase I clinical trial testing the ability of Trichuris suis ova treatment to improve the clinical course of MS. A complex interaction between the CNS (including the blood-brain barrier), multiple infections with various infectious agents (occurring in the periphery or within the CNS), and the immune response to those various infections may have to be deciphered before the etiology of MS can be fully understood.

Do bugs control our fate? The influence of the microbiome on autoimmunity

Autoimmune disease has traditionally been thought to be due to the impact of environmental factors on genetically susceptible individuals causing immune dysregulation and loss of tolerance. However, recent literature has highlighted the importance of the microbiome, (a collective genome of microorganisms in a given niche) in immune homeostasis. Increasingly, it has been recognized that disruptions in the commensal microflora may lead to immune dysfunction and autoimmunity. This review summarizes recent studies investigating the interplay between the microbiome and immune-mediated organ-specific diseases. In particular, we review new findings on the role of the microbiome in inflammatory bowel disease, celiac disease, psoriasis, rheumatoid arthritis, type I diabetes, and multiple sclerosis.

Optic neuritis

AIMS

The aim of this study is to provide a clinical update on optic neuritis (ON), its association with multiple sclerosis (MS), and neuromyelitis optica (NMO).

METHODS

This study included a PubMed review of the literature written in the English language.

RESULTS

ON in adults is typically idiopathic or demyelinating, and is characterised by unilateral, subacute, painful loss of vision that is not associated with any systemic or other neurological symptoms. Demyelinating ON is associated with MS, and we review the key studies of ON including the ON treatment trial and several other MS treatment trials and NMO.

CONCLUSION

Acute demyelinating ON can occur in isolation or be associated with MS. Typical ON does not require additional evaluation other than cranial magnetic resonance imaging. NMO is likely a separate disorder from MS and the ON in NMO has a different treatment and prognosis.

METHODOLOGY

The authors conducted an English language search using Pubmed from the years 1964 to 2010 using the search terms 'ON', 'MS' and 'NMO'. The authors included original articles, review articles, and case reports, which revealed new aspects as far as epidemiology, histopathology, clinical manifestations, imaging, genetics, and treatment of ON. Titles were reviewed for topicality and full references were obtained. Letters to the editor, unpublished work, and abstracts were not included in this review.