Bcl-2/Bax ratio increase does not prevent apoptosis of glia and granular neurons in patients with temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is usually associated with hippocampal sclerosis (HS), characterized by gliosis and neuronal loss, mainly in the cornus ammonis (CA). Regardless the type of HS, gliosis is associated with neuronal loss. Indeed, glial reactivation seems to induce both neuronal and glial apoptosis. Anti-apoptotic mechanisms are also activated in order to contain the cell death in chronic epilepsy. However, the role of the intrinsic apoptosis pathway in human TLE is unclear, mainly in relation to glial death. The purpose of this study was to evaluate the reactive gliosis areas in parallel with Bcl-2/Bax ratio and active caspase 3 immunoreactivity in hippocampi of TLE patients in comparison with control hippocampi. We also sought to investigate whether the levels of these markers were correlated with TLE clinical parameters. Paraffin-embedded sclerotic and control hippocampi were collected for immunohistochemical analyses of glial fibrillary acidic protein (GFAP), human leucocyte antigen DR (HLA-DR), neuronal nuclei protein (NeuN), Bax, Bcl-2 and active caspase 3. Sclerotic hippocampi presented higher immunoreactivity areas of GFAP and HLA-DR than controls, with similar values in HS types 1 and 2. Bcl-2 protein expression was increased in epileptic hippocampi, while Bax expression was similar to controls. Despite Bcl2/Bax ratio increase, granular neurons and glia exhibited active caspase 3 expression in TLE hippocampi, while controls did not show staining for the same marker. In conclusion, glial and neuronal death is increased in sclerotic hippocampi, independently of HS type, and co-localized with gliosis. Furthermore, Bcl-2/Bax ratio increase does not prevent expression of active caspase 3 by glia and granular neurons in TLE.

Influenza A Virus as a Predisposing Factor for Cryptococcosis.

Influenza A virus (IAV) infects millions of people annually and predisposes to secondary bacterial infections. Inhalation of fungi within the Cryptococcus complex causes pulmonary disease with secondary meningo-encephalitis. Underlying pulmonary disease is a strong risk factor for development of C. gattii cryptococcosis though the effect of concurrent infection with IAV has not been studied. We developed an in vivo model of Influenza A H1N1 and C. gattii co-infection. Co-infection resulted in a major increase in morbidity and mortality, with severe lung damage and a high brain fungal burden when mice were infected in the acute phase of influenza multiplication. Furthermore, IAV alters the host response to C. gattii, leading to recruitment of significantly more neutrophils and macrophages into the lungs. Moreover, IAV induced the production of type 1 interferons (IFN-α4/ß) and the levels of IFN-γ were significantly reduced, which can be associated with impairment of the immune response to Cryptococcus during co-infection. Phagocytosis, killing of cryptococci and production of reactive oxygen species (ROS) by IAV-infected macrophages were reduced, independent of previous IFN-γ stimulation, leading to increased proliferation of the fungus within macrophages. In conclusion, IAV infection is a predisposing factor for severe disease and adverse outcomes in mice co-infected with C. gattii.