HIV infection of brain

the biologics basis of neuropsycology

Abstract

Introduction: the importance of neuropsycological manifestations as was to identify the presence of HIV-1 in Central Nervous System. Objectives:to evaluate possible correlation among HIV-1 in central nervous system (CNS), pathological mechanism, protection of CNS and cognitive neuropsychological disorders. To identify the existence or lack of cognitive neuropsychological symptoms and their importance as HIV-1 enters CNS. Method: systematic review of more than 100 papers published recently in national and international medical literature via PubMed, concerning bio-logical and pathological mechanisms related to HIV-1 in CNS and cognitive neuropsychological functions. It has been established correlation amongbiological, pathological, neuropsychological aspects and controversial issues of clinical importance in HIV-1- infected patients. Results: Most ofselected papers suppose that HIV-1 enters immunologically privileged CNS early in the course of infection and establishes its life long niche inbrain. The principal pathway of HIV-1 entry in brain is through the increased influx of infected monocytes into CNS. Direct injury of brain neuronmay occur involving various viral proteins such as Tat, gp120,Vpr. It has been suggested that in such situation direct interaction of HIV-1 proteinskill the neuron without any intermediate role of glial cells. Indirect injury seems to be the most frequent way as various diffusible products of activated monocytes , macrophages, astrocytes and microglia induce death processes in non-specific innocent bystander neurons. In contrast to most paperspublished there are studies which recommend protective role of HIV-1 that could activate astrocytes and microglia with preservation of cognitivefunction promoting neuronal protection. Discussion: the results of this systematic review show that HIV-1 in the brain could promote different seve-rities of cognitive neuropsychological disorders according to biological interaction of HIV-1 in CNS. In case of direct attack of HIV-1 to cerebral neurons (direct neurotoxicity) severe cognitive neuropsychological disorders could certainly occur. In case of neurotoxicity where infiltratedmonocytes, macrophages, microglia and astrocytes produce various cytokines, chemokines, aminoacids, HIV-1 proteins and other difusible products,neurons could be injured or die depending on the intensity of initial insult. The cognitive neuropsychological disorders could be light, mild or severeaccording to the intensity of the brain injury. In case of the lack of cognitive neuropsychological symptoms when HIV-1 has infected the brain somepublished evidences show a possible neuroprotective role of some cytokines such as TNF produced by infiltrated monocytes and glial cells.Conclusion: Neuropsychological tests may be important for prognostic evaluation and adequate treatment of HIV-1 infection of CNS and for deter-mination of the clinical course of the patient. Neuropsychological disorders may work as markers of aggression or protection for CNS infected byHIV-1. Viral activity of HIV-1 in CNS may be inferred through neuropsychogical disorders observed.