DECREASED mRNA EXPRESSION OF TIGHT JUNCTION PROTEINS IN LUMBAR SPINAL CORDS OF PATIENTS WITH ALS

Studies using mSOD1 transgenic mice, an animal model of familial amyotrophic lateral sclerosis (fALS), suggest that endothelial damage and impaired integrity of the blood–brain barrier (BBB) and blood–spinal cord barrier (BSCB) occur before signs of weakness and may contribute to motoneuron injury, further implicating a non-cell-autonomous pathogenesis.1–3 While tight junctions were still intact in late symptomatic mSOD1 animals, there were ultrastructural alterations in the BBB and BSCB and leakage of Evans Blue dye from spinal cord microvessels at both early and late stages of disease.1,2 A recent study also demonstrated the presence of microhemorrhages and further showed decreased expression of the tight junction proteins zona occludens 1 (ZO-1), occludin (Ocln), and claudin-5 (Cldn5) in mSOD1 mice during disease progression.3 To investigate whether tight junction proteins are decreased in patients with ALS, the mRNA expression of ZO-1, Ocln, and Cldn5 was assessed in spinal cord tissue from patients with sporadic ALS (sALS), patients with fALS, and non-neurodegenerative disease controls (NNDC). ### Methods. After receiving written consent and approval by The Methodist Hospital or the University of Pittsburgh School of Medicine, postmortem tissue samples were obtained from patients with a definite diagnosis of ALS according to WFN El Escorial/Airlie criteria. RNA was extracted from homogenized lumbar spinal cord specimens from 30 patients with sALS, 4 patients with fALS, and 16 NNDC with Trizol (Invitrogen, Grand Island, NY) and purified with an RNeasy kit (Qiagen, Valencia, CA). Quantitative reverse transcriptase PCR (RT-PCR) was performed using 10 ng of RNA, an iScript One-step RT-PCR kit with SYBR Green (Bio-Rad, Hercules, CA), and assayed on an iQ5 Multicolor …