The role of mast cells and diet in the onset and maintenance of multiple sclerosis: a hypothesis

Signaling pathways in the activation of mast cells cocultured with astrocytes and colocalization of both cells in experimental allergic encephalomyelitis

Mast cells in the CNS participate in the pathophysiology of chronic neurodegenerative inflammatory diseases. This study aimed to investigate the signaling pathway of mast cells activated in an environment cocultured with astrocytes and to explore the role of their colocalization in brain of experimental allergic encephalomyelitis. Human mast cell line-1 cells and human U87 glioblastoma cell lines (U87) or mouse bone marrow-derived mast cells and mouse cerebral cortices-derived astrocytes were cocultured. Intracellular Ca(2+) was measured by confocal microscopy; histamine by fluorometric analyzer; leukotrienes by ELISA; small GTPases, protein kinase Cs, MAPK, c-kit, CD40, and CD40L by Western blot; NF-kappaB and AP-1 by EMSA; cytokines by RT-PCR; and colocalization of mast cells and astrocytes in brain by immunohistochemistry. Mast cells cocultured with astrocytes showed time-dependent increases in intracellular Ca(2+) levels, release of histamine and leukotrienes, and cytokine production. Mast cells or astrocytes showed enhanced surface expression of CD40L and CD40, respectively, during coculture. Mast cells cocultured with astrocytes induced small GTPases (Rac1/2, cdc42), protein kinase Cs, MAPK, NF-kappaB, and AP-1 activities. These changes were blocked by anti-CD40 Ab pretreatment or CD40 small interfering RNA. Mast cells increased in the thalamus of experimental allergic encephalomyelitis model, particularly colocalized with astrocytes in the thalamic border region of the habenula. In conclusion, the data suggest that activation of mast cells cocultured with astrocytes induces release of mediators by small GTPases/Ca(2+) influx through CD40-CD40L interactions to participate in the pathophysiology of chronic neurodegenerative inflammatory diseases, such as multiple sclerosis.

Phosphate depletion is the link between growth, stress and diet in the aetiology of MS

Predisposition to multiple sclerosis (MS) can originate in adolescence, when nutrient requirement is high and not satisfied and because of too little food intake and/or a poor diet. Growth per se increases the need for phosphate, an often neglected mineral in clinical conditions. The combination of marginal nutrition (either under- or malnutrition) with a negative phosphate balance, physical exertion, infections or other types of stress during puberty can disturb metabolism and result in demyelinization. Phosphate depletion (PD) can lead to neurological complications, which have been characterized in experimental and clinical studies. Hypophosphataemia, whether acute or chronic, induced by stress from accident, surgery or burns, by infection and/or undernutrition, is therefore an important etiological factor. Low SP levels have been reported in MS patients and the hypothesis that PD causes MS is presented here.

Mast cells: new targets for multiple sclerosis therapy?

Growing evidence suggests that mast cells (MCs) play a crucial role in the inflammatory process and the subsequent demyelination observed in patients suffering from multiple sclerosis (MS). Although no consensus exists on the role of mast cells in multiple sclerosis, recent results from animal models clearly indicate that these cells act at multiple levels to influence both the induction and the severity of disease. In addition to changing our views on the pathophysiology of multiple sclerosis, the concept that mast cells are critical for the outcome of the disease could have an important impact on the development of new therapeutic approaches.

Mast cells and multiple sclerosis: a quantitative analysis

The average number of mast cells observed in multiple sclerosis (MS) plaques from four patients, was 0.35 mast cells per mm2. This number represents 1/100 of the amount found in normal human skin. Most mast cells were observed in the border zones of the MS plaques and were clustered in restricted areas along venules and capillaries, which represent the main area of oedema formation in the brain. This cell type may be considered as a contributor to the pathogenesis of oedema formation and subsequent myelin destruction in MS.