Increase in brain stem cytokine mRNA levels as an early response to chemical-induced myelin edema

Methylated Metal(loid) Species in Humans

While the metal(loid)s arsenic, bismuth, and selenium (probably also tellurium) have been shown to be enzymatically methylated in the human body, this has not yet been demonstrated for antimony, cadmium, germanium, indium, lead, mercury, thallium, and tin, although the latter elements can be biomethylated in the environment. Methylated metal(loid)s exhibit increased mobility, thus leading to a more efficient metal(loid) transport within the body and, in particular, opening chances for passing membrane barriers (blood-brain barrier, placental barrier). As a consequence human health may be affected. In this review, relevant data from the literature are compiled, and are discussed with respect to the evaluation of assumed and proven health effects caused by alkylated metal(loid) species.

Modelling neuroinflammatory phenotypes in vivo

Inflammation of the central nervous system is an important but poorly understood part of neurological disease. After acute brain injury or infection there is a complex inflammatory response that involves activation of microglia and astrocytes and increased production of cytokines, chemokines, acute phase proteins, and complement factors. Antibodies and T lymphocytes may be involved in the response as well. In neurodegenerative disease, where injury is more subtle but consistent, the inflammatory response is continuous. The purpose of this prolonged response is unclear, but it is likely that some of its components are beneficial and others are harmful. Animal models of neurological disease can be used to dissect the specific role of individual mediators of the inflammatory response and assess their potential benefit. To illustrate this approach, we discuss how mutant mice expressing different levels of the cytokine transforming growth factor beta-1 (TGF-beta1), a major modulator of inflammation, produce important neuroinflammatory phenotypes. We then demonstrate how crosses of TGF-beta1 mutant mice with mouse models of Alzheimer's disease (AD) produced important new information on the role of inflammation in AD and on the expression of different neuropathological phenotypes that characterize this disease.

Increased expression of MIP-1 alpha and MIP-1 beta mRNAs in the brain correlates spatially and temporally with the spongiform neurodegeneration induced by a murine oncornavirus

The chimeric murine oncornavirus FrCas(E) causes a rapidly progressive paralytic disease associated with spongiform neurodegeneration throughout the neuroaxis. Neurovirulence is determined by the sequence of the viral envelope gene and by the capacity of the virus to infect microglia. The neurocytopathic effect of this virus appears to be indirect, since the cells which degenerate are not infected. In the present study we have examined the possible role of inflammatory responses in this disease and have used as a control the virus F43. F43 is an highly neuroinvasive but avirulent virus which differs from FrCas(E) only in 3' pol and env sequences. Like FrCas(E), F43 infects large numbers of microglial cells, but it does not induce spongiform neurodegeneration. RNAase protection assays were used to detect differential expression of genes encoding a variety of cytokines, chemokines, and inflammatory cell-specific markers. Tumor necrosis factor alpha (TNF-alpha) and TNF-beta mRNAs were upregulated in advanced stages of disease but not early, even in regions with prominent spongiosis. Surprisingly there was no evidence for upregulation of the cytokines interleukin-1 alpha (IL-1 alpha), IL-1 beta, and IL-6 or of the microglial marker F4/80 at any stage of this disease. In contrast, increased levels of the beta-chemokines MIP-1 alpha and -beta were seen early in the disease and were concentrated in regions of the brain rich in spongiosis, and the magnitude of responses was similar to that observed in the brains of mice injected with the glutamatergic neurotoxin ibotenic acid. MIP-1alpha and MIP-1beta mRNAs were also upregulated in F43-inoculated mice, but the responses were three- to fivefold lower and occurred later in the course of infection than was observed in FrCas(E)-inoculated mice. These results suggest that the robust increase in expression of MIP-1 alpha and MIP-1 beta in the brain represents a correlate of neurovirulence in this disease, whereas the TNF responses are likely secondary events.