Circulating tight junction proteins mirror blood-brain barrier integrity in leukaemia central nervous system metastasis.

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, ALB(CSF) and BBB values in leukaemia patients. Among all of the parameters studied, CLDN5(CSF) 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 (c) 2016 John Wiley & Sons, Ltd.