RESUMO
BACKGROUND: As important mediators of solute transport at the blood-brain and blood-cerebrospinal fluid barriers, ATP-binding cassette (ABC) transporters (including ABCB1, ABCC1, and ABCC2), impact the bioavailability of drugs and endogenous substrates in the brain. While several ABCB1, ABCC1, and ABCC2 single nucleotide polymorphisms (SNPs) have been identified, their impact on outcome after traumatic brain injury (TBI) is unknown. HYPOTHESIS: ABCB1, ABCC1, and ABCC2 SNPs are associated with Glasgow Outcome Scale (GOS) score after TBI. METHODS: DNA samples from 305 adult patients with severe TBI (Glasgow Coma Scale, GCS score ≤ 8) were genotyped for tagging SNPs of ABCB1 (rs1045642; rs1128503), ABCC1 (rs212093; rs35621; rs4148382), and ABCC2 (rs2273697). For each SNP, patients were dichotomized based on presence of variant allele for multivariate analysis to determine associations with GOS assigned at 6 months adjusting for GCS, Injury Severity score, age, and patient sex. RESULTS: For ABCB1 rs1045642, patients homozygous for the T allele were less likely to be assigned poor outcome versus those possessing the C allele [CT/CC; odds of unfavorable GOS = 0.71(0.55-0.92)]. For ABCC1 rs4148382, patients homozygous for the G allele were less likely to be assigned poor outcome versus those possessing the A allele [AG/AA; odds of unfavorable GOS = 0.73(0.55-0.98)]. CONCLUSIONS: In this single-center study, patients homozygous for the T allele of ABCB1 rs1045642 or the G allele of ABCC1 rs4148382 were found to have better outcome after severe TBI. Further study is necessary to replicate these very preliminary findings and to determine whether these associations are due to central nervous system bioavailability of ABC transporter drug substrates commonly used in the management of TBI, brain efflux of endogenous solutes, or both.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Lesões Encefálicas/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Adolescente , Adulto , Idoso , Barreira Hematoencefálica/fisiologia , Lesões Encefálicas/metabolismo , Feminino , Escala de Coma de Glasgow , Homozigoto , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Proteína 2 Associada à Farmacorresistência Múltipla , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Polimorfismo de Nucleotídeo Único , Recuperação de Função Fisiológica/genética , Adulto JovemRESUMO
Heme oxygenase 1 (HO-1) is an enzyme important in the catabolism of heme that is induced under conditions of oxidative stress. HO-1 degradation of heme yields biliverdin, bilirubin, carbon monoxide and iron. HO-1 is thought to serve a protective antioxidant function, and upregulation of HO-1 has been demonstrated in experimental models of neurodegeneration, subarachnoid hemorrhage, cerebral ischemia and traumatic brain injury (TBI). We measured HO-1 concentration in cerebral spinal fluid samples from 48 infants and children following TBI and 7 control patients by ELISA. Increased HO-1 was seen in TBI versus control patients--mean 2.75+/-0.63, peak 4.17+/-0.96 ng/ml versus control (<0.078 ng/ml, not detectable) (p<0.001). Increased HO-1 concentration was associated with increased injury severity and unfavorable neurological outcome (both p<0.05). Increased HO-1 concentration was independently associated with younger age; however, statistical analysis could not rule out the possibility that the effect of age was related to inflicted TBI from child abuse. HO-1 increases after TBI and appears to be more prominent in infants compared with older children after injury.