ABSTRACT
Germinal matrix haemorrhage (GMH), caused by rupturing blood vessels in the germinal matrix, is a prevalent driver of preterm brain injuries and death. Our group recently developed a model simulating GMH using intrastriatal injections of collagenase in 5-day-old rats, which corresponds to the brain development of human preterm infants. This study aimed to define changes to the blood-brain barrier (BBB) and to evaluate BBB proteins as biomarkers in this GMH model. Regional BBB functions were investigated using blood to brain 14C-sucrose uptake as well as using biotinylated BBB tracers. Blood plasma and cerebrospinal fluids were collected at various times after GMH and analysed with ELISA for OCLN and CLDN5. The immunoreactivity of BBB proteins was assessed in brain sections. Tracer experiments showed that GMH produced a defined region surrounding the hematoma where many vessels lost their integrity. This region expanded for at least 6 h following GMH, thereafter resolution of both hematoma and re-establishment of BBB function occurred. The sucrose experiment indicated that regions somewhat more distant to the hematoma also exhibited BBB dysfunction; however, BBB function was normalised within 5 days of GMH. This shows that GMH leads to a temporal dysfunction in the BBB that may be important in pathological processes as well as in connection to therapeutic interventions. We detected an increase of tight-junction proteins in both CSF and plasma after GMH making them potential biomarkers for GMH.
Subject(s)
Blood-Brain Barrier/metabolism , Cerebral Hemorrhage/blood , Claudin-5/genetics , Corpus Striatum/metabolism , Hematoma/blood , Occludin/genetics , Tight Junctions/metabolism , Animals , Animals, Newborn , Biological Transport , Biomarkers/blood , Biomarkers/cerebrospinal fluid , Blood-Brain Barrier/ultrastructure , Cerebral Hemorrhage/chemically induced , Cerebral Hemorrhage/genetics , Cerebral Hemorrhage/pathology , Claudin-5/blood , Claudin-5/cerebrospinal fluid , Collagenases/administration & dosage , Corpus Striatum/blood supply , Corpus Striatum/pathology , Disease Models, Animal , Gene Expression , Hematoma/chemically induced , Hematoma/genetics , Hematoma/pathology , Humans , Infant, Newborn , Infant, Premature , Injections, Intraventricular , Occludin/blood , Occludin/cerebrospinal fluid , Rats , Rats, Wistar , Sucrose/metabolism , Tight Junctions/ultrastructureABSTRACT
BACKGROUND: Neonatal encephalopathy often leads to lifelong disabilities with limited treatments currently available. The brain vasculature is an important factor in many neonatal neurological disorders but there is a lack of diagnostic tools to evaluate the brain vascular dysfunction of neonates in the clinical setting. Measurement of blood-brain barrier tight-junction (TJ) proteins have shown promise as biomarkers for brain injury in the adult. Here we tested the biomarker potential of tight-junctions in the context of neonatal brain injury. METHODS: The levels of TJ-proteins (occluding, claudin-5, and zonula occludens protein 1) in both blood plasma and cerebrospinal fluid (CSF) as well as blood-brain barrier function via 14C-sucrose (342 Da) and Evans blue extravasation were measured in a hypoxia/ischemia brain-injury model in neonatal rats. RESULTS: Time-dependent changes of occludin and claudin-5 levels could be measured in blood and CSF after hypoxia/ischemia with males generally having higher levels than females. The levels of claudin-5 in CSF correlated with the severity of the brain injury at 24 h post- hypoxia/ischemia. Simultaneously, we detected early increase in blood-brain barrier-permeability at 6 and 24 h after hypoxia/ischemia. CONCLUSIONS: Levels of circulating claudin-5 and occludin are increased after hypoxic/ischemic brain injuries and blood-brain barrier-impairment and have promise as early biomarkers for cerebral vascular dysfunction and as a tool for risk assessment of neonatal brain injuries.
Subject(s)
Biomarkers/metabolism , Blood-Brain Barrier/metabolism , Claudin-5/metabolism , Hypoxia-Ischemia, Brain/metabolism , Occludin/metabolism , Zonula Occludens-1 Protein/metabolism , Animals , Biomarkers/blood , Biomarkers/cerebrospinal fluid , Claudin-5/blood , Claudin-5/cerebrospinal fluid , Disease Models, Animal , Female , Hypoxia-Ischemia, Brain/blood , Hypoxia-Ischemia, Brain/cerebrospinal fluid , Male , Occludin/blood , Occludin/cerebrospinal fluid , Rats , Rats, Wistar , Zonula Occludens-1 Protein/blood , Zonula Occludens-1 Protein/cerebrospinal fluidABSTRACT
The aim of this study was to evaluate the clinical significance of circulating tight junction (TJ) proteins as biomarkers reflecting of leukaemia central nervous system (CNS) metastasis. TJs [claudin5 (CLDN5), occludin (OCLN) and ZO-1] concentrations were measured in serum and cerebrospinal fluid (CSF) samples obtained from 45 leukaemia patients. Serum ZO-1 was significantly higher (p < 0.05), but CSF ZO-1 levels were not significantly higher in the CNS leukaemia (CNSL) compared to the non-CNSL. The CNSL patients also had a lower CLDN5/ZO1 ratio in both serum and CSF than in non-CNSL patients (p < 0.05). The TJ index was negatively associated with WBCCSF , ALBCSF and BBB values in leukaemia patients. Among all of the parameters studied, CLDN5CSF had the highest specificity in discriminating between CNSL and non-CNSL patients. Therefore, analysing serum and CSF levels of CLDN5, OCLN and the CLDN5/ZO1 ratio is valuable in evaluating the potential of leukaemia CNS metastasis. Copyright © 2016 John Wiley & Sons, Ltd.
