Previous infection with Staphylococcus aureus strains attenuated experimental encephalomyelitis

Staphylococcal enterotoxin B increased severity of experimental model of multiple sclerosis

BACKGROUND

Superantigens can be absorbed trans-mucosal and trans-cutaneous in individuals colonized with superantigen producing Staphylococcus aureus. Ability of superantigens to activate a large numbers of T cells suggests that they may play a role in the course of autoimmune diseases including human multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). In this study we investigated the role of staphylococcal enterotoxin B in immunologic and pathologic changes in experimental animal model of multiple sclerosis.

METHODS

C57BL/6 female mice were treatment with SEB protein prior or post immunization with MOG33-35 peptide. Mice were monitored daily and scored for clinical symptoms following EAE induction. Spleen and spinal cord of mice were removed and used for ELISA and histological studies, respectively.

RESULTS

Treatment with SEB prior induction of EAE, increased clinical score, the concentration of IL-17A, IFN-γ and histological changes compared to control group. Treatment with SEB after induction of EAE caused these changes, but less severe.

DISCUSSION

Since SEB causes demyelination of spinal cord and increases the level of pro-inflammatory cytokine response, infiltration of T-lymphocytes and macrophages to CNS, it may exacerbate the clinical signs of EAE in mice and multiple sclerosis in human.

Frequency of superantigen encoding genes of Staphylococcus aureus isolates collected from multiple sclerosis (MS) patients and nasal carriers

BACKGROUND

Bacterial superantigens are potent T cell activators that can have acute or chronic effects on the central nervous system.

OBJECTIVES

In this study, the role of enterotoxins, exfoliative toxins and toxic shock syndrome toxin of Staphylococcus aureus was investigated in MS patients and healthy nasal carriers.

METHODS

Three-hundred fifty nasal swabs were collected from healthy nasal carriers (n = 210) and MS (n = 140) patients. Staphylococcus aureus superantigens were detected by multiplex PCR. Antimicrobial susceptibility pattern was performed using disk diffusion method.

RESULTS

The highest rates of nasal colonization were seen in MS patients (46.42%). The rates of nasal colonization in the healthcare workers were 30.95%. The most commonly detected superantigens were SEA (31.5%), SEB (17.7%) and ETA (16.9%). The Staphylococcus aureus isolates had the highest levels of resistance against erythromycin (57.7%), clindamycin (55.4%) and co-trimoxazole (43.1%). All isolates were susceptible to vancomycin, linezolid, and mupirocin.

CONCLUSION

Our results revealed that the frequency of superantigen producing Staphylococcus aureus isolates is high in the MS patients. As well as these isolates are sensitive to mupirocin. Thus it is better to use of mupirocin for nasal decolonization of Staphylococcus aureus in the MS patients.

Oral infection with P. gingivalis exacerbates autoimmune encephalomyelitis

BACKGROUND

Oral infection of mice with P. gingivalis induces periodontal inflammation and attachment loss. The aim of the present study was to investigate whether infection of mice with P. gingivalis, exacerbates the clinical course of experimental autoimmune encephalomyelitis (EAE)-a mouse model of multiple sclerosis (MS).

METHODS

Induction of EAE was carried out by immunization of C57BL/6 mice with myelin oligodentrocyte glycoprotein (MOG_35-55 ). P. gingivalis infection was induced via subcutaneous chambers model and the oral gavage. The severity of EAE was measured using a clinical severity score. Ex-vivo reactivation of lymphocytes with the encephalitogenic peptide MOG_35-55 was also tested.

RESULTS

Subcutaneous as well as oral infection with live P. gingivalis led to significant aggravation of the severity of EAE. Lymph node cells harvested from mice with EAE following P. gingivalis infection showed augmented lymphocyte proliferation towards the encephlatigenic MOG moiety compared to mice with EAE only.

CONCLUSIONS

The present results indicate that oral infection with P. gingivalis augmented the severity of EAE. This may stem from the systemic pro-inflammatory response triggered by P. gingivalis infection or via antigen mimicking. The present study provides evidence that periodontal infection may play a role as modifier in CNS inflammatory disorders, such as MS.

Tolerogenic Vaccination with MOG/VitD Overcomes Aggravating Effect of C. albicans in Experimental Encephalomyelitis

AIMS

Multiple sclerosis (MS) is an immune-mediated demyelinating disorder of the central nervous system (CNS). We described that Candida albicans (Ca) aggravates experimental autoimmune encephalomyelitis (EAE) that is a model to study MS. We also observed that vaccination with a myelin peptide (MOG) in the presence of vitamin D (VitD) protected mice against EAE. In this work, we investigated whether Ca infection interferes with the efficacy of this vaccine.

METHODS

EAE was induced in C57BL/6 female mice previously vaccinated with MOG+VitD and then infected 3 days before encephalomyelitis induction.

RESULTS

Vaccination was able to control EAE development in infected mice. These animals gained weight, and only a few progressed to very low clinical scores. Protection was confirmed by a lower inflammatory infiltration in the CNS and was also associated with a reduced production of encephalitogenic cytokines by spleen and CNS cell cultures. The elevated percentage of CD25(+) FoxP3(+) cells suggests that regulatory T cells are involved in the protection. Adoptive transfer of splenocytes from mice vaccinated with MOG+VitD supports the view that protection is mediated by immunoregulatory cells.

CONCLUSION

Together, these experiments provide evidence demonstrating that EAE can be prevented by the inverse vaccination with MOG+VitD even in the presence of a disease-aggravating infectious agent.

Infection as an Environmental Trigger of Multiple Sclerosis Disease Exacerbation

Over the past several decades, significant advances have been made in identifying factors that contribute to the pathogenesis of multiple sclerosis (MS) and have culminated in the approval of some effective therapeutic strategies for disease intervention. However, the mechanisms by which environmental factors, such as infection, contribute to the pathogenesis and/or symptom exacerbation remain to be fully elucidated. Relapse frequency in MS patients contributes to neurological impairment and, in the initial phases of disease, serves as a predictor of poor disease prognosis. The purpose of this review is to examine the evidence that supports a role for peripheral infection in modulating the natural history of this disease. Evidence supporting a role for infection in promoting exacerbation in animal models of MS is also reviewed. Finally, a few mechanisms by which infection may exacerbate symptoms of MS and other neurological diseases are discussed. Those who comprise the majority of MS patients acquire approximately two upper-respiratory infections per year; furthermore, this type of infection doubles the risk for MS relapse, underscoring the contribution of this relationship as being potentially important and particularly detrimental.

Resistant Strains of Enterotoxigenic Staphylococcus aureus; Unknown Risk for Multiple Sclerosis Exacerbation

Background:

Despite all advances in neurological sciences, there are unknown aspects in the epidemiology of multiple sclerosis (MS). Based on this hypothesis, the enterotoxigenic strains of Staphylococcus aureus (S. aureus) are possible risk factors for exacerbations of MS.

Objectives:

The present study was carried out to investigate the role of resistant strains of enterotoxigenic S. aureus in MS exacerbation.

Materials and Methods:

Two-hundred nasal swab samples were collected from non-MS (n = 80), MS stable (n = 60) and MS exacerbation (n = 60) groups. Samples were cultured and those that were S. aureus-positive were analyzed for the presence of enterotoxins, using polymerase chain reaction (PCR). Antimicrobial susceptibility was performed using disk diffusion method.

Results:

Ninety out of 200 nasal samples (45%) were positive for S. aureus. The highest levels of nasal colonization were seen in MS exacerbation group (68.33%). The most commonly detected enterotoxins were sea (30%), sec (15.55%) and seb (11.11%). There were significant differences between S. aureus colonization and type of samples (P = 0.026) and, also, between type of samples and prevalence of enterotoxins (P = 0.022). The highest levels of enterotoxigenic genes were seen in MS exacerbation group. The S. aureus strains had the highest levels of resistance against tetracycline (80%), ampicillin (72.22%), methicillin (66.66%), erythromycin (66.66%), oxacillin (63.33%), trimethoprim-sulfamethoxazole (61.11%) and cotrimoxazole (55.55%).

Conclusions:

Our findings should raise awareness about the role of sea and sec enterotoxins, in resistant strains of S. aureus, as a risk factor for MS exacerbation. It is better to keep MS patients away from polluted environments of hospitals and health centers.

Beneficial effect of chronic Staphylococcus aureus infection in a model of multiple sclerosis is mediated through the secretion of extracellular adherence protein

Background

Bacterial infections have been assumed to worsen multiple sclerosis (MS) disease symptoms and to lead to increased neurodegeneration. However, the underlying biological mechanisms for these effects are complex and poorly understood. Here, we assessed the disease-modulating effects of chronic infection with Staphylococcus aureus, a common human pathogen, on the clinical course and the extent of neurodegeneration in experimental autoimmune encephalomyelitis (EAE), an animal model of MS.

Methods

To conduct this study, we established a persistent chronic infection in female brown Norway rats by inoculating Staphylococcus aureus (S. aureus) bacteria in a subcutaneously implanted tissue cages.

Results

In this study, we observed that the introduction of a localized S. aureus infection during the subclinical phase of EAE induced a chronic systemic inflammatory response, consisting of increased T- and B-cell counts and systemic production of proinflammatory cytokines. Unexpectedly, the S. aureus infection completely prevented the development of clinical EAE, and markedly reduced inflammatory infiltration and demyelination of the optic nerve, while it increased the number of surviving retinal neurons. Using a S. aureus strain that lacked the extracellular adherence protein (Eap), we determined that the extracellular adherence protein is at least partially responsible for the inhibitory effect of S. aureus infection on autoimmune inflammation of the central nervous system.

Conclusions

Our results demonstrate for the first time that chronic infection with S. aureus has a beneficial effect on EAE, indicating a dual role of infection in the pathogenesis of MS. We also showed that secretion of Eap by S. aureus plays a major role in preventing autoimmune inflammation of the CNS. Moreover, we identified Eap as a factor responsible for this protective effect.