guanosine-triphosphate and Central-Nervous-System-Diseases

A potential mechanism that may contribute to neurological deficits following central nervous system infection in children was investigated. Quinolinic acid (QUIN) is a neurotoxic metabolite of the kynurenine pathway that accumulates within the central nervous system following immune activation. The present study determined whether the levels of QUIN are increased in the cerebrospinal fluid of children with infections of the CNS, hydrocephalus, tumors or hemorrhage. Extremely high QUIN concentrations were found in patients with bacterial infections or the CNS, despite treatment with antimicrobial agents. CSF QUIN levels were also elevated to a lesser degree in patients with hydrocephalus or tumors. CSF L-kynurenine levels increased in parallel to the accumulations in QUIN, which is consistent with increased activity of the first enzyme of the kynurenine pathway, indoleamine-2,3-dioxygenase. The CSF levels of neopterin, a marker of immune and macrophage activation, were also increase in patients with infections. The cytokines tumor necrosis factor-alpha and interleukin-6 were also detected in some patients' samples, and were highest in patients with infection. These results suggest that QUIN is a sensitive marker of the presence of immune activation within the CNS. Further studies of QUIN as a potential contributor to neurologic dysfunction and neurodegeneration in children with CNS inflammation are warranted.

Topics: Adolescent; Adult; Bacterial Infections; Biomarkers; Biopterins; Central Nervous System Diseases; Central Nervous System Neoplasms; Cerebral Hemorrhage; Child; Child, Preschool; Female; Guanosine Triphosphate; Humans; Hydrocephalus; Infant; Infant, Newborn; Interleukin-6; Kynurenine; Male; Neopterin; Quinolinic Acid; Tryptophan Oxygenase; Tumor Necrosis Factor-alpha

Developmental retardation was a prominent clinical feature in six infants from three kindreds deficient in the enzyme purine nucleoside phosphorylase (PNP) and was present before development of T cell immunodeficiency. Guanosine triphosphate (GTP) depletion was noted in the erythrocytes of all surviving homozygotes and was of equivalent magnitude to that found in the Lesch-Nyhan syndrome (complete hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency). The similarity between the neurological complications in both disorders indicates that the two major clinical consequences of complete PNP deficiency have differing aetiologies: neurological effects resulting from deficiency of the PNP enzyme products, which are the substrates for HGPRT, leading to functional deficiency of this enzyme. immunodeficiency caused by accumulation of the PNP enzyme substrates, one of which, deoxyguanosine, is toxic to T cells. These studies show the need to consider PNP deficiency (suggested by the finding of hypouricaemia) in patients with neurological dysfunction, as well as in T cell immunodeficiency. They suggest an important role for GTP in normal central nervous system function.

Topics: Central Nervous System; Central Nervous System Diseases; Child; Child, Preschool; Deficiency Diseases; Developmental Disabilities; Erythrocytes; Female; Guanosine Triphosphate; Humans; Male; Pentosyltransferases; Purine-Nucleoside Phosphorylase