Increased ciliary neurotrophic factor in blood serum and lacrimal fluid as a potential biomarkers of focal epilepsy

Purpose To evaluate ciliary neurotrophic factor (CNTF) level in blood serum (BS) and lacrimal fluid (LF) of people with epilepsy (PWE). Methods A case-control study of 72 consecutive patients with focal epilepsy (cases, epilepsy group) and 60 age- and gender-matched healthy volunteers (controls) was performed. Based on comorbid depression, two subgroups of PWE were formed. CNTF level was measured by an enzyme-linked immunosorbent assay (ELISA) in the BS and LF. For measurements of low CNTF levels in the BS, the methodology previously improved by the authors was applied. Results As compared to controls, CNTF level (pg/mL) in PWE was increased both in the BS (7.0 +/- 2.9 vs. 3.7 +/- 2.0, P<0.000) and in LF (34.0 +/- 8.0 vs. 30.6 +/- 4.8, P=0.005). No significant correlation was found between CNTF level in the BS and LF either in PWE or in controls. No impact of comorbid depression or any demographic or clinical parameters studied on CNTF level in the BS or LF of PWE could be detected. Conclusions In patients with focal epilepsy, CNTF level is increased both in the BS and LF, though without correlation between them. No association of CNTF levels with age, gender, or clinical parameters, as well as depression occurrence, was found. High CNTF levels in the BS and LF could be considered as non-invasive biomarkers of focal epilepsy.