Expression of neurotrophic factors in cerebrospinal fluid and plasma of children with viral and bacterial meningoencephalitis

Aim: To evaluate the expression of neurotrophic factors (nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF)) and their association with the clinical-radiological characteristics and outcome of children with viral and bacterial meningoencephalitis (ME). Methods: Prospective observational clinical study performed on 13 children with ME and 12 controls with non-inflammatory obstructive hydrocephalus. Neurotrophic factor levels in the cerebro-spinal fluid (CSF) and plasma were measured using an immunoenzymatic assay. Results: High levels of NGF and BDNF were demonstrated in all patients, while GDNF levels did not undergo significant variations. NGF expression in the CSF was higher in viral ME than in bacterial ME and was correlated with CSF cellularity (particularly mononuclear cells). BDNF expression in the CSF was higher in bacterial ME than in viral ME and was correlated with CSF cellularity and blood platelet count. No relationships were noted between CSF protein or serum C-reactive protein levels and the expression of neurotrophic factors. Regarding clinical and radiological features, elevated NGF/BDNF levels in the CSF correlated with higher incidence of seizures and prolonged comatose state and with specific radiological lesions. No correlation was found between NGF/BDNF levels and final outcome. Conclusions: The variations in neurotrophic factor levels may reflect an endogenous attempt at neuroprotection against biochemical and molecular changes during both viral and bacterial ME. The expression of these factors is likely to play a neuro-immunomodulatory or neurosurvival role in ME infections.