Bacterial toxins and Multiple Sclerosis

Environmental factors related to multiple sclerosis progression

Multiple Sclerosis (MS) is a complex neurological disease which prevalence is increasing worldwide. The impact of environmental factors on MS susceptibility has already been defined and highlighted in many previous reports, particularly vitamin D or ultraviolet B light exposure, Epstein-Barr virus (EBV) infection, obesity, and smoking. There is increasing evidence that environmental and lifestyle factors are not only important in triggering MS but are also implicated in MS progression. Low sun exposure and vitamin D deficiency exhibit a strong relationship with disease progression in both animal and human studies. The gestational period seems also to impact long-term disease progression as January's babies had a higher risk of requiring walking assistance than those born in other months. The implication of EBV in neurodegeneration and MS progression was also suggested even though its specific targets and mechanisms are still unclear. Cigarette smoking is correlated with faster clinical progression. The association of obesity and smoking seems to be associated with a faster progression and an increased rate of brain atrophy. Although the effect of air pollution on MS pathogenesis remains not fully understood, exposure to polluted air can stimulate several mechanisms that might contribute to MS severity. People with MS with active disease have an altered microbiota compared to patients in the remission phase. Cardiovascular comorbidities, epilepsy, and depression are also associated with a more severe disability accrual. Knowledge about MS modifiable risk factors of progression need to be incorporated into everyday clinical practice in order to ameliorate disease outcomes.

Bacterial transportable toxins of the nasopharyngeal microbiota in multiple sclerosis. Nose-to-brain direct

Intranasal administration delivers molecules directly to the brain bypassing the blood-brain barrier. Three distinct routes of access have been identified; olfactory, trigeminal and via the paranasal sub-mucosa of the posterior sinuses. Consequently, environmental toxins may access the CNS directly to induce inflammatory and degenerative disease. They may also activate bacterial species of the nasal mucosal microbiome to release both immune-deviating cell wall antigens and transportable neurotoxins with local direct access to the CNS. Evidence is reviewed that toxins of the nasal bacterial microbiota may be directly implicated in the inflammatory and degenerative pathogenesis of multiple sclerosis.

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.

Potential role of the Virchow Robin space in the pathogenesis of bacterial meningitis

Meningitis is an infectious disease commonly arising from a bacterial etiology. The rapid progression of morbidity and mortality due to bacterial meningitis requires critical and imminent time-dependent clinical intervention. Although it is unambiguously clear that bacteria must infiltrate the cerebrospinal fluid, the sequence of events in the pathogenesis of bacterial meningitis has not been fully elucidated. Most reviews of the pathogenesis of bacterial meningitis do not specify the anatomical location of bacteria following BBB traversal. We propose an additional hypothesis focusing on the Virchow-Robin space (VRS). The VRS consists of a small, but identifiable perivascular space formed by a sheath of cells derived from the pia mater. The VRS has been described as an immunological space and possibly having a role in several neuropathological diseases. Solute exchange between cerebrospinal fluid and extracellular fluid occurs at the VRS, with subsequent drainage into the subarachnoid space. Because the VRS is continuous with the subpial space, a more direct route to the meninges is facilitated. The involvement of the VRS may have profound implications on the pathogenesis and therapeutic strategies: (1) nasopharyngeal colonization; (2) penetration into the blood stream after crossing the mucosal and epithelial membranes; (3) proliferation in the bloodstream; (4) extravasations through the endothelium of the post-capillary venules to the perivascular VRS; (5) migration from VRS to subpial space; (6) traversal through pia mater, entering the CSF in the subarachnoid space; (7) invasion of the meninges. The implication of the VRS in the pathogenesis of bacterial meningitis would be twofold. First, the VRS could provide an additional route of entry of bacteria into the brain. Second, the VRS could provide an area for bacterial proliferation, and thereby serve as a bacterial reservoir in relatively close proximity to the meninges. The clinical consequences of this hypothesis are: 1) clinical interpretation of laboratory findings, and 2) effective antibiotic delivery into the VRS. If the role of the VRS is established as part of bacterial meningitis pathogenesis, antibiotic pharmacokinetics and pharmacodynamics in the VRS need to be determined. This may result in developing novel antibiotic delivery and clinical strategies to improve morbidity and mortality.

Back on the scent: the olfactory system in CNS demyelinating diseases

Olfactory dysfunction is recognised across an ever broadening spectrum of neuropsychiatric conditions including central nervous system (CNS) demyelinating diseases such as multiple sclerosis (MS) and neuromyelitis optica (NMO). In this review, we unravel the striking evidence highlighting how olfactory loss is a common clinical feature in MS and NMO. We provide an overview of the supportive psychophysical, electrophysiological, radiological and pathological data that point to the anatomical substrate of olfactory deficits in these diseases. The pattern of underlying pathology affecting the olfactory system is shown to be complex, involving multiple structures that are affected in different ways throughout the course of the disease. This review is the first to synthesise the expanding body of literature on the topic, provides novel insight into the way in which the olfactory system is affected in CNS demyelinating diseases, and raises intriguing questions about the role of this system in the pathogenesis of these diseases.

Clinical and symptomatological reflections: the fascial system

Every body structure is wrapped in connective tissue, or fascia, creating a structural continuity that gives form and function to every tissue and organ. Currently, there is still little information on the functions and interactions between the fascial continuum and the body system; unfortunately, in medical literature there are few texts explaining how fascial stasis or altered movement of the various connective layers can generate a clinical problem. Certainly, the fascia plays a significant role in conveying mechanical tension, in order to control an inflammatory environment. The fascial continuum is essential for transmitting muscle force, for correct motor coordination, and for preserving the organs in their site; the fascia is a vital instrument that enables the individual to communicate and live independently. This article considers what the literature offers on symptoms related to the fascial system, trying to connect the existing information on the continuity of the connective tissue and symptoms that are not always clearly defined. In our opinion, knowing and understanding this complex system of fascial layers is essential for the clinician and other health practitioners in finding the best treatment strategy for the patient.

Characterization of microcirculation in multiple sclerosis lesions by dynamic texture parameter analysis (DTPA)

Objective

Texture analysis is an alternative method to quantitatively assess MR-images. In this study, we introduce dynamic texture parameter analysis (DTPA), a novel technique to investigate the temporal evolution of texture parameters using dynamic susceptibility contrast enhanced (DSCE) imaging. Here, we aim to introduce the method and its application on enhancing lesions (EL), non-enhancing lesions (NEL) and normal appearing white matter (NAWM) in multiple sclerosis (MS).

Methods

We investigated 18 patients with MS and clinical isolated syndrome (CIS), according to the 2010 McDonald's criteria using DSCE imaging at different field strengths (1.5 and 3 Tesla). Tissues of interest (TOIs) were defined within 27 EL, 29 NEL and 37 NAWM areas after normalization and eight histogram-based texture parameter maps (TPMs) were computed. TPMs quantify the heterogeneity of the TOI. For every TOI, the average, variance, skewness, kurtosis and variance-of-the-variance statistical parameters were calculated. These TOI parameters were further analyzed using one-way ANOVA followed by multiple Wilcoxon sum rank testing corrected for multiple comparisons.

Results

Tissue- and time-dependent differences were observed in the dynamics of computed texture parameters. Sixteen parameters discriminated between EL, NEL and NAWM (pAVG = 0.0005). Significant differences in the DTPA texture maps were found during inflow (52 parameters), outflow (40 parameters) and reperfusion (62 parameters). The strongest discriminators among the TPMs were observed in the variance-related parameters, while skewness and kurtosis TPMs were in general less sensitive to detect differences between the tissues.

Conclusion

DTPA of DSCE image time series revealed characteristic time responses for ELs, NELs and NAWM. This may be further used for a refined quantitative grading of MS lesions during their evolution from acute to chronic state. DTPA discriminates lesions beyond features of enhancement or T2-hypersignal, on a numeric scale allowing for a more subtle grading of MS-lesions.

Staphylococcal immune complexes and myelinolytic toxin in early acute multiple sclerosis lesions-An immunohistological study supported by multifactorial cluster analysis and antigen-imprint isoelectric focusing

Highly significant clinical, epidemiological and pathogenetic similarities between multiple sclerosis (MS) and nasopharyngeal sinusitis has led to the hypothesis that MS is caused by the inadvertent incorporation of the lymphatic drainage of the nasopharynx into the extracellular fluid circulation of the CNS. It has been postulated that, in response to antigenic and toxic products generated by the mucosal nasopharygeal flora, the leptomeninges and CNS parenchyma acquire the characteristics of a persistently stimulated lymphoid organ. Using an extensive panel of bacterial antibodies, tissues from exceptionally early cases, identified and classified using multifactorial cluster analysis, were screened for bacterial antigens using immunohistological methods. Anti-staphylococcal antibodies detected antigen co-locating with IgG/C3d immune complexes in pre-demyelinating and in primary lesions. The distribution of the antigen in relation to the morphogenesis of early acute MS lesions is detailed. Evidence for the intrathecal processing of staphylococcal antigen was obtained using isoelectric focusing and antigen imprinting to identify antigen-specific oligoclonal bands. Employing a combination of isoelectric focusing, western blotting and mass spectrometric analysis, evidence for the intrathecal processing of staphylococcal β-haemolysin (sphingomyelinase) was obtained using CSF from MS cases. While a myelinolytic transportable toxin may be an important component in the pathogenesis of demyelination, in oligodendrocyte apoptosis, and in deviant immune responses within the CNS, the detection of other as yet unidentified staphylococcal-positive and negative oligoclonal bands points to the involvement of a cocktail of transportable antigens leaking in a similar manner into the CNS from the paranasal sinus mucosal tissues where these molecules are conserved by the resident flora to manipulate and subvert the normal processes of local and systemic immunity. Evidence for the access of other bacterial transportables to the CNS in MS should now be sought. The presence of 'high-output' toxigenic bacterial strains within the nasopharyngeal flora of MS patients should also be explored. The use of tracer molecules to detect and quantify nose-to-brain transport in MS patients is clearly apposite.