TNF-receptor 1 deficiency fails to alter the clinical and pathological course in mice with globoid cell leukodystrophy (twitcher mice) but affords protection following LPS challenge.

Twitcher mice have an autosomal recessive mutation in the gene for the lysosomal enzyme galactosylceramidase, which is the same gene that is affected in human globoid cell leukodystrophy (Krabbe's disease). The failure to digest galactosylceramide and psychosine leads to initial pathological changes in oligodendrocytes. Secondary pathological changes that include infiltrating macrophages and other inflammatory responses have been postulated to promote the disease course. TNFalpha levels are elevated in twitcher mice compared to control animals, and studies on another demyelinating disease, experimental allergic encephalomyelitis, indicate that TNF promotes pathogenesis via TNF-receptor 1 (TNF-R1). In the present study, twitcher/TNF-R1 deficient mice were generated, and the clinical and pathological course was compared between these mice and regular twitcher mice. There was no statistical evidence for any differences between these two groups of mice for all clinical (life span, weight loss, onset day of twitching) and pathological (demyelination, astrocyte gliosis, macrophage infiltration) measures that were examined. If mice were administered an intraperitoneal injection of LPS, then twitcher/TNF-R1 deficient mice had a longer [corrected] life span and a decreased [corrected] disruption to the blood-brain barrier compared to regular twitcher mice. These results showed that TNF-R1 is not sufficiently activated to affect the pathological and/or clinical signs during the natural course of this disease. However, when there is a secondary insult, TNF-R1 activation does lead to a significant acceleration of the development of clinical and pathological signs.

L-cycloserine slows the clinical and pathological course in mice with globoid cell leukodystrophy (twitcher mice).

Globoid cell leukodystrophy (Krabbe's disease) is an autosomal recessive disease that affects the lysosomal enzyme galactosylceramidase. Galactosylceramidase removes galactose from galactosylceramide and psychosine, which are derived from sphingosine. In the present study, L-cycloserine (an inhibitor of 3-ketodyhydrosphingosine synthase) was administered to the twitcher mouse, an authentic model of globoid cell leukodystrophy. Twitcher mice treated with L-cycloserine had a significantly longer life span and a delayed onset of weight loss than vehicle-injected twitcher mice. Pathological features such as macrophage infiltration and astrocyte gliosis also were less in treated twitcher mice. These results indicate that substrate reduction therapy may have therapeutic value for individuals with residual enzymatic activity, e.g., individuals with late onset disease or individuals with partial enzyme replacement via bone marrow transplantation. In these cases, a reduction in galactosylceramide and psychosine synthesis would enable residual enzymatic activity to keep up with the accumulation of these substrates that would otherwise lead to pathology.

IL-6 deficiency causes enhanced pathology in Twitcher (globoid cell leukodystrophy) mice.

The expression of IL-6 is greatly enhanced in the twitcher mouse (S. M. LeVine and D. C. Brown, 1997, J. Neuroimmunol. 73, 47-56), which is an authentic animal model of globoid cell leukodystrophy (Krabbe's disease). In order to investigate the role of IL-6 in this disease, twitcher/IL-6-deficient mice were generated and the pathology was compared between them and regular twitcher mice. Twitcher/IL-6-deficient mice had a more severe disease than regular twitcher mice: they had an earlier onset day of twitching, a greater number of PAS-positive cells, a greater susceptibility to LPS, an exaggerated gliotic response around some vessels, an elevated level of TNF-alpha, and a compromised blood-brain barrier, which was evaluated by three independent measures. This latter finding indicates that IL-6 plays a role in maintaining the integrity of the BBB, and it raises the possibility that IL-6 functions in a similar manner in other diseases of the CNS. LPS was found to greatly shorten the life of twitcher and twitcher/IL-6-deficient mice compared to genotyped-matched saline-injected mice. This result indicates that a proinflammatory condition can exacerbate an underlying CNS pathology, which could help explain why some leukodystrophy patients display their initial symptoms following a fever or blow to the head.

Iron deposits in the central nervous system of SJL mice with experimental allergic encephalomyelitis.

Iron has been proposed to promote oxidative tissue damage in multiple sclerosis (MS). In order to gain insights about how iron gets processed during MS, the deposition of iron was investigated in the CNS of mice with experimental allergic encephalomyelitis (EAE), which is a commonly used animal model of MS. Control mice (adjuvant only) and EAE mice (myelin basic protein plus adjuvant), were sacrificed at 4-8 days (preclinical phase), 10-13 days (clinical phase), or 18 days (recovery phase) post injection. Sections from the cerebrum, hindbrain, and cervical, thoracic and lumbar spinal cord were stained as previously described (J. Neurosci. Res. 29:413, 1991), and scored blindly for histopathological staining. There was minimal histopathological staining at any age in control animals or during the preclinical stage in EAE animals. At the clinical stage of EAE, stained pathological features (macrophages, extravasated RBC and granular staining) were significantly increased compared to the preclinical stage. In the recovery phase, macrophage and granular staining persisted but there was loss of extravasated RBC. Dual labeling studies revealed that granular deposits were present in astrocytes and in locations that appeared to be extracellular. In order to gain insights about the origin of iron deposits in EAE mice, additional studies were performed on brains of mice with extravasated blood lesions. These brains had granular, macrophage and RBC staining. Thus, each of the stained features in EAE animals could be due to the extravasation of blood which occurs in the SJL model of EAE, although some of the iron could have originated from myelin and oligodendrocytes damaged during EAE.

Desferrioxamine suppresses experimental allergic encephalomyelitis induced by MBP in SJL mice.

Data from several studies indicate that free radicals have a pathogenic role in experimental allergic encephalomyelitis (EAE). Iron can contribute to free radical damage by catalyzing the formation of hydroxyl radical, inducing secondary initiation of lipid peroxidation and by promoting the oxidation of proteins. The iron chelator, desferrioxamine, can limit these oxidative reactions and it can scavenge peroxynitrite independent of iron chelation. Two previous studies have examined the therapeutic value of desferrioxamine in EAE. One study observed an effect when disease was induced by spinal cord homogenates (J. Exp. Med. 160, p. 1532, 1984), but a second study found no therapeutic value of desferrioxamine for myelin basic protein (MBP)-induced EAE (J. Neuroimmunol. 17, p. 127, 1988). In the second study, the drug was only administered during the preclinical stages of disease. Since desferrioxamine scavenges free radicals and prevents their formation, we hypothesized that the drug should be given during the active stage of disease to have therapeutic value. We first demonstrated that the drug enters the CNS around inflammatory cells in EAE animals. In animals treated during the active stage of MBP-induced EAE, the clinical signs were significantly reduced compared to vehicle-treated animals. The iron-bound form of this drug, ferrioxamine, was without therapeutic value. A derivative of desferrioxamine, hydroxylethyl starch (HES)-desferrioxamine, has a greater plasma half-life than desferrioxamine and it was also tested. Although there was a suggestion of improvement in these animals, the effects were less than that observed for desferrioxamine which may be related to the greater molecular size of HES-desferrioxamine. In summary, these data suggest that chelation of iron is an effective therapeutic target for EAE.

[Anticyan--a new highly effective antidote in cyanide poisoning]. / Antitsian--novyi vysokoéffektivnyi antidot pri otravlenii tsianidami.

Anticyan is a highly effective antidote of cyanic acid and cyanide-containing compounds. It was created at the Institute of Pharmacology and Toxicology of AMS of Ukraine. Anticyan differs from other existing cyanide antidotes in that it possesses a tready methemoglobin-formation activity, has no hypotensive effect and is capable of direct stimulation of cyanide-inhibited tissue respiration.