Heme oxygenase-1 as a therapeutic target in neurodegenerative diseases and brain infections.

Heme oxygenase-1 (HO-1) catalyzes the degradation of heme to generate carbon monoxide, biliverdin and free iron. Increased HO-1 levels constitute an anatomopathological feature of many neurological diseases, such as neurodegenerative disorders and brain infections, which correlate with exacerbated oxidative stress and inflammation. It is generally accepted that the elevated HO-1 levels represent an attempt to restore redox homeostasis and to down-modulate inflammation. However, experimental observations indicate that the extent of HO-1 induction may be critical because excessive heme degradation may result in toxic levels of CO, bilirubin and, more importantly, iron. Pharmacological modulation of HO-1 levels in the brain, within therapeutic limits, shows promising results in models of Alzheimer's (AD), Parkinson's (PD) and of infectious diseases, such as malaria. A more complete understanding on how HO-1 is involved in the pathogenesis of neurological diseases will be essential to develop therapeutic approaches. In the next coming years we will witness the description of chemicals, drugs or dietary products that cross the blood brain barrier efficiently, activate HO-1 expression, and achieve neuroprotective and anti-inflammatory effects in vivo.

Monoamine oxidase inhibition and CNS immunodeficiency infection.

HIV invades CNS subcortical areas, particularly the dopamine-rich basal ganglia and induces a subcortical dementia. Data suggest that the basal ganglia dysfunction plays a critical role in the neuropsychiatric manifestation of HIV infection. Therefore, therapeutic approaches for HIV dementia nowadays wish to include apart from the highly active antiretroviral therapy (HAART) also adjunctive medication. In this short article, we report briefly on neurotoxicity associated with the immunodeficiency virus and discuss the effects of selegiline, a monoamine oxidase inhibitor which enhances dopamine availability in CNS on immunodeficiency virus-induced neurological disease.

Critical role for protein tyrosine phosphatase SHP-1 in controlling infection of central nervous system glia and demyelination by Theiler's murine encephalomyelitis virus.

We previously characterized the expression and function of the protein tyrosine phosphatase SHP-1 in the glia of the central nervous system (CNS). In the present study, we describe the role of SHP-1 in virus infection of glia and virus-induced demyelination in the CNS. For in vivo studies, SHP-1-deficient mice and their normal littermates received an intracerebral inoculation of an attenuated strain of Theiler's murine encephalomyelitis virus (TMEV). At various times after infection, virus replication, TMEV antigen expression, and demyelination were monitored. It was found that the CNS of SHP-1-deficient mice uniquely displayed demyelination and contained substantially higher levels of virus than did that of normal littermate mice. Many infected astrocytes and oligodendrocytes were detected in both brains and spinal cords of SHP-1-deficient but not normal littermate mice, showing that the virus replicated and spread at a much higher rate in the glia of SHP-1-deficient animals. To ascertain whether the lack of SHP-1 in the glia was primarily responsible for these differences, glial samples from these mice were cultured in vitro and infected with TMEV. As in vivo, infected astrocytes and oligodendrocytes of SHP-1-deficient mice were much more numerous and produced more virus than did those of normal littermate mice. These findings indicate that SHP-1 is a critical factor in controlling virus replication in the CNS glia and virus-induced demyelination.