A new EAE model of brain demyelination induced by intracerebroventricular pertussis toxin

Dual Mechanism of Action of Curcumin in Experimental Models of Multiple Sclerosis

Background: Multiple sclerosis (MS) is characterized by a combination of inflammatory and demyelination processes in the spinal cord and brain. Conventional drugs generally target the autoimmune response, without any curative effect. For that reason, there is a great interest in identifying novel agents with anti-inflammatory and myelinating effects, to counter the inflammation and cell death distinctive of the disease. Methods and results: An in vitro assay showed that curcumin (Cur) at 10 µM enhanced the proliferation of C8-D1A cells and modulated the production of Th1/Th2/Th17 cytokines in the cells stimulated by LPS. Furthermore, two in vivo pathophysiological experimental models were used to assess the effect of curcumin (100 mg/kg). The cuprizone model mimics the de/re-myelination aspect in MS, and the experimental autoimmune encephalomyelitis model (EAE) reflects immune-mediated events. We found that Cur alleviated the neurological symptomatology in EAE and modulated the expression of lymphocytes CD3 and CD4 in the spinal cord. Interestingly, Cur restored motor and behavioral deficiencies, as well as myelination, in demyelinated mice, as indicated by the higher index of luxol fast blue (LFB) and the myelin basic protein (MBP) intensity in the corpus callosum. Conclusions: Curcumin is a potential therapeutic agent that can diminish the MS neuroimmune imbalance and demyelination through its anti-inflammatory and antioxidant effects.

Role of Major Toxin Virulence Factors in Pertussis Infection and Disease Pathogenesis

Bordetella pertussis produces several toxins that affect host-pathogen interactions. Of these, the major toxins that contribute to pertussis infection and disease are pertussis toxin, adenylate cyclase toxin-hemolysin and tracheal cytotoxin. Pertussis toxin is a multi-subunit protein toxin that inhibits host G protein-coupled receptor signaling, causing a wide array of effects on the host. Adenylate cyclase toxin-hemolysin is a single polypeptide, containing an adenylate cyclase enzymatic domain coupled to a hemolysin domain, that primarily targets phagocytic cells to inhibit their antibacterial activities. Tracheal cytotoxin is a fragment of peptidoglycan released by B. pertussis that elicits damaging inflammatory responses in host cells. This chapter describes these three virulence factors of B. pertussis, summarizing background information and focusing on the role of each toxin in infection and disease pathogenesis, as well as their role in pertussis vaccination.

Contribution of pertussis toxin to the pathogenesis of pertussis disease

Pertussis toxin (PT) is a multisubunit protein toxin secreted by Bordetella pertussis, the bacterial agent of the disease pertussis or whooping cough. PT in detoxified form is a component of all licensed acellular pertussis vaccines, since it is considered to be an important virulence factor for this pathogen. PT inhibits G protein-coupled receptor signaling through Gi proteins in mammalian cells, an activity that has led to its widespread use as a cell biology tool. But how does this activity of PT contribute to pertussis, including the severe respiratory symptoms of this disease? In this minireview, the contribution of PT to the pathogenesis of pertussis disease will be considered based on evidence from both human infections and animal model studies. Although definitive proof of the role of PT in humans is lacking, substantial evidence supports the idea that PT is a major contributor to pertussis pathology, including the severe respiratory symptoms associated with this disease.

Valproic Acid attenuates disease symptoms and increases endogenous myelin repair by recruiting neural stem cells and oligodendrocyte progenitors in experimental autoimmune encephalomyelitis

BACKGROUND

inefficient remyelination of demyelinated plaques in multiple sclerosis (ms) leads to secondary axon degeneration and progressive disability. therapies that potentiate remyelination would be of immense help for managing MS.

OBJECTIVE

Here, we report the effects of valproic acid (VPA) on focal experimental autoimmune encephalomyelitis (fEAE).

METHODS

fEAE was induced in Wistar rats by immunizing the animals with guinea pig spinal cord homogenate emulsified in complete Freund's adjuvant and with pertussis toxin (PT) injection into the spinal cord at the level of T8 vertebra on day 18 after immunization. VPA 300 mg/kg was applied for 4 days after or 8 days before PT administration. Behavioral evaluation, histological assessment and immunohistofluorescence assays were used to evaluate the outcomes.

RESULTS

VPA administration had no effect on the development of symptoms, but after discontinuing VPA, animals showed faster recovery. Eight days of pretreatment with VPA accelerated the recovery phase of EAE and increased the number of remyelinated axons in the lesion area. VPA pretreatment also increased the recruitment of neural stem cells and oligodendrocyte precursors within the lesion.

CONCLUSIONS

Results suggest VPA as a potential therapy for remyelinating the lesions in MS and for faster recovery from disease relapses. The effect of VPA seems to be mediated by endogenous progenitors recruitment.

Pertussis toxin exacerbates and prolongs airway inflammatory responses during Bordetella pertussis infection

Throughout infection, pathogenic bacteria induce dramatic changes in host transcriptional repertoires. An understanding of how bacterial factors influence host reprogramming will provide insight into disease pathogenesis. In the human respiratory pathogen Bordetella pertussis, the causative agent of whooping cough, pertussis toxin (PT) is a key virulence factor that promotes colonization, suppresses innate immune responses during early infection, and causes systemic disease symptoms. To determine the full extent of PT-associated gene regulation in the airways through the peak of infection, we measured global transcriptional profiles in the lungs of BALB/c mice infected with wild-type (WT) or PT-deficient (ΔPT) B. pertussis. ΔPT bacteria were inoculated at a dose equivalent to the WT dose and at a high dose (ΔPT(high)) to distinguish effects caused by higher bacterial loads achieved in WT infection from effects associated with PT. The results demonstrated that PT was associated with a significant upregulation of immune and inflammatory response genes as well as several other genes implicated in airway pathology. In contrast to the early, transient responses observed for ΔPT(high) infection, WT infection induced a prolonged expression of inflammatory genes and increased the extent and duration of lung histopathology. In addition, the administration of purified PT to ΔPT(high)-infected mice 1 day after bacterial inoculation exacerbated and prolonged inflammatory responses and airway pathology. These data indicate that PT not only is associated with exacerbated host airway responses during peak B. pertussis infection but also may inhibit host mechanisms of attenuating and resolving inflammation in the airways, suggesting possible links between PT and pertussis disease symptoms.

Pertussis-associated encephalitis/encephalopathy with marked demyelination in an unimmunized child

Encephalitis/encephalopathy is a rare, but severe, complication of pertussis. Here, we report a case of an unimmunized 7-year-old boy with confirmed pertussis complicated by acute encephalitis/encephalopathy. Eighteen days after the onset of pertussis, generalized seizures began. Magnetic resonance imaging (MRI) indicated that marked demyelination without cytotoxic edema may have occurred to the patient. Notably, this is the first report to show precise MRI findings of pertussis-associated encephalitis/encephalopathy. Markedly increased myelin basic protein levels in the cerebrospinal fluid were consistent with the MRI findings. There was no evidence of direct invasion of the causative bacterium or its products into the central nervous system. The levels of interleukin-6 and -10 in the cerebrospinal fluid were higher than those in serum. Taken together, we conclude that indirect immune-mediated mechanisms may have contributed to the pathogenesis of the encephalitis/encephalopathy.

APOE 4 polymorphism results in early cognitive deficits in an EAE model

Recent clinical studies have identified an association between APOE 4 and cognitive deficits in patients with multiple sclerosis. We induced experimental autoimmune encephalomyelitis (EAE) in APOE knockout (KO) and human APOE 4 knockin (E4) mice to study the interaction of APOE and neuroinflammation on cognition. After EAE induction, KO and E4 showed significant deficits in spatial learning and recall. Regional decreases in choline acetyltransferase localized to the hippocampus. Induction of EAE in a transgenic APOE animal provides a template from which we can decipher the role APOE has on cognition in the context of neuroinflammation.