Toxin-Based Models to Investigate Demyelination and Remyelination.

Clinical myelin diseases, and our best experimental approximations, are complex entities in which demyelination and remyelination proceed unpredictably and concurrently. These features can make it difficult to identify mechanistic details. Toxin-based models offer lesions with predictable spatiotemporal patterns and relatively discrete phases of damage and repair: a simpler system to study the relevant biology and how this can be manipulated. Here, we discuss the most widely used toxin-based models, with a focus on lysolecithin, ethidium bromide, and cuprizone. This includes an overview of their respective mechanisms, strengths, and limitations and step-by-step protocols for their use

Reduction of microglial activity in a model of multiple sclerosis by dipyridamole

BACKGROUND: Despite extensive and persistent activation of microglia in multiple sclerosis (MS), microglia inhibitors have not yet been identified for treatment of the disorder. We sought to identify medications already in clinical use that could inhibit the activation of microglia. On the basis of the reported inhibitory effects of dipyridamole on phosphodiesterase activity that result in the production of various anti-inflammatory outcomes, we selected it for study. Dipyridamole is used clinically for secondary prevention in stroke. In this study, dipyridamole was examined using microglia in culture and in the mouse model of MS, experimental autoimmune encephalomyelitis (EAE). RESULTS: We found that dipyridamole attenuated the elevation of several cytokines and chemokines in human microglia caused by Toll-like receptor stimulation. Morphological characteristics of activated microglia in culture were also normalized by dipyridamole. In mice, dipyridamole decreased the clinical severity of EAE and reduced microglial activity and other histological indices of EAE in the spinal cord. CONCLUSIONS: Dipyridamole is an inhibitor of microglia activation and may have a role in MS and other neurological conditions to attenuate microglial activity

AMINO-ACID-SEQUENCE OF TSTX-V, AN ALPHA-TOXIN FROM TITYUS-SERRULATUS SCORPION-VENOM, AND ITS EFFECT ON K+ PERMEABILITY OF BETA-CELLS FROM ISOLATED RAT ISLETS OF LANGERHANS

Highly purified Tityustoxin V (TsTX-V), an alpha-toxin isolated from the venom of the Brazilian scorpion Tityus serrulatus, was obtained by ion exchange chromatography on carboxymethylcellulose-52. It was shown to be homogeneous by reverse phase high performance liquid chromatography, N-terminal sequencing (first 39 residues) of the reduced and alkylated protein and by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate and tricine. Following enzymatic digestion, the complete amino acid sequence (64 residues) was determined. The sequence showed higher homology with the toxins from the venoms of the North African than with those of the North and South American scorpions. Using the rate of Rb-86(+) release from depolarized rat pancreatic beta-cells as a measure of K+ permeability changes, TsTX-V (5.6 mu g/ml) was found to increase by 2.0-2.4-fold the rate of marker outflow in the presence of 8.3 mM glucose. This effect was persistent and slowly reversible, showing similarity to that induced by 100 mu-M veratridine, an agent that increases the open period of Na+ channels, delaying their inactivation. It is suggested that, by extending the depolarized period, TsTX-V indirectly affects beta-cell voltage-dependent K+ channels, thus increasing K+ permeability

Initial Pulmonary Respiration Causes Massive Diaphragm Damage and Hyper-CKemia in Duchenne Muscular Dystrophy Dog

The molecular mechanism of muscle degeneration in a lethal muscle disorder Duchene muscular dystrophy (DMD) has not been fully elucidated. The dystrophic dog, a model of DMD, shows a high mortality rate with a marked increase in serum creatine kinase (CK) levels in the neonatal period. By measuring serum CK levels in cord and venous blood, we found initial pulmonary respiration resulted in massive diaphragm damage in the neonates and thereby lead to the high serum CK levels. Furthermore, molecular biological techniques revealed that osteopontin was prominently upregulated in the dystrophic diaphragm prior to the respiration, and that immediate-early genes (c-fos and egr-1) and inflammation/immune response genes (IL-6, IL-8, COX-2, and selectin E) were distinctly overexpressed after the damage by the respiration. Hence, we segregated dystrophic phases at the molecular level before and after mechanical damage. These molecules could be biomarkers of muscle damage and potential targets in pharmaceutical therapies

C-terminal truncation of IFN-γ\gamma inhibits proinflammatory macrophage responses and is deficient in autoimmune disease

International audienceControlled macrophage differentiation and activation in the initiation and resolution of inflammation is crucial for averting progression to chronic inflammatory and autoimmune diseases. Here we show a negative feedback mechanism for proinflammatory IFN-$\gamma$ activation of macrophages driven by macrophage-associated matrix metalloproteinase 12 (MMP12). Through C-terminal truncation of IFN-$\gamma$ at 135Glu↓Leu136 the IFN-$\gamma$ receptor-binding site was efficiently removed thereby reducing JAK-STAT1 signaling and IFN-$\gamma$ activation of proinflammatory macrophages. In acute peritonitis this signature was absent in Mmp12$^{–/–}$ mice and recapitulated in Mmp12$^{+/+}$ mice treated with a MMP12-specific inhibitor. Similarly, loss-of-MMP12 increases IFN-$\gamma$–dependent proinflammatory markers and iNOS$^+$/MHC class II$^+$ macrophage accumulation with worse lymphadenopathy, arthritic synovitis and lupus glomerulonephritis. In active human systemic lupus erythematosus, MMP12 levels were lower and IFN-$\gamma$ higher compared to treated patients or healthy individuals. Hence, macrophage proteolytic truncation of IFN-$\gamma$ attenuates classical activation of macrophages as a prelude for resolving inflammation

ECPPA: Randomised trial of low dose aspirin for the prevention of maternal and fetal complications in high risk pregnant women

Objective To determine the effectiveness of low dose aspirin in women at high risk of adverse outcomes associated with pre-eclampsia.Design A collaborative randomised trial comparing the effects of low dose aspirin (60 mg) with placebo on pre-eclampsia and other materno-fetal complications associated with hypertension.Setting Twelve teaching maternity hospitals and 182 obstetricians' offices in Brazil.Subjects One thousand and nine women considered to be at high risk for the development of preeclampsia, or its complications, entered the study between 12 and 32 weeks of gestation. They were randomly allocated to receive aspirin (498 women) or placebo (511 women) until delivery, and follow up was obtained for 96%.Results There were no significant differences between the treatment groups in the incidence of proteinuric pre-eclampsia (6.7% aspirin-allocated compared with 6.0% placebo-allocated women), of preterm delivery (22.3% compared with 26.1%), of intrauterine growth retardation (8.5% compared with 10.1%), or of stillbirth and neonatal death (7.3% compared with 6.0%), nor were there significant differences in the incidence of proteinuric pre-eclampsia in any subgroup of women studied, including those who had systolic blood pressures of 120 mmHg or above at entry (8.5% compared with 7.3%) or those who were chronically hypertensive (10.0% compared with 7.1%). Aspirin was not associated with a significant excess of maternal or fetal bleeding.Conclusion The results of this study do not support the routine prophylactic administration of low dose aspirin in pregnancy to any category of high risk women (even those who have chronic hypertension or who are considered to be especially liable to early onset pre-eclampsia).ESCOLA PAULISTA MED,DEPT MED,MED CLIN D,RUA BOTUCATU 740,BR-04023900 SAO PAULO,BRAZILESCOLA PAULISTA MED,DEPT MED,MED CLIN D,RUA BOTUCATU 740,BR-04023900 SAO PAULO,BRAZILWeb of Scienc