Status epilepticus (SE) in children frequently induces ultrastructural damage to cerebral white matter myelin. Claudin 11, a key molecule maintaining radial tight junctions in myelin, whose deficiency significantly reduces nerve conduction velocity and causes behavioral abnormalities. This study investigated the effects of Claudin 11 overexpression on myelin structural integrity and spatial cognition post-SE in mice.

Eighteen 21-day-old male C57 BL/6J mice, weighing 9 to 11 g, were randomly divided into two groups (n=9) using a random number table. The SE group received an intraperitoneal injection of 7.5 mg/kg kainic acid (KA, 2 mg/mL) to induce SE, while the Ctrl group received an equal volume of normal saline. Twenty days after SE induction, when the mice reached 41 days of age and weighed 16 to 26 g, the following assessments were performed: ① Western blotting was used to detect Claudin 11 and myelin basic protein (MBP) protein expression levels in the hippocampus (n=6 per group); ② immunofluorescence staining was employed to observe the distribution of Claudin 11 protein in the hippocampus (n=3). An additional 40 male C57 BL/6J mice, 16-day-old and weighing 6 to 9 g, were randomly divided into 4 groups (n=10) using a random number table. The CV+SE group received an intracerebroventricular (ICV) injection of Claudin 11-overexpressing virus ScAAV2/9-CV-CLDN11-ZsGreen (viral titer: 0.8×10¹³ vg/mL), and was given the same dose of KA 5 days after virus intervention (at 21 days of age). The NV+SE group received an ICV injection of negative control empty vector virus ScAAV2/9-CMS-ZsGreen (viral titer: 1.1×10¹³ vg/mL), and was given the same dose of KA 5 days after intervention (at 21 days of age). Mice in the SE group and Ctrl group were housed under the same conditions until 21 days of age for the experiment; the SE group received an intraperitoneal injection of 7.5 mg/kg KA (2 mg/mL), and the Ctrl group received an equal volume of normal saline. Twenty days after SE induction, when the mice reached 41 days of age and weighed 16 to 26 g, the following assessments were performed: ① transmission electron microscopy was used to observe the myelin sheath ultrastructure in the hippocampus (n=3); ② the open field test, elevated plus maze, Y-maze, and Morris water maze were used to evaluate anxiety-like behavior and spatial learning and memory ability (n=7).

① Western blot analysis showed that compared with the Ctrl group, Claudin 11 protein (P=0.0077) and MBP protein expression (P=0.0336) in the hippocampus of the SE group were significantly decreased. ② Immunofluorescence staining showed that, in both the Ctrl and SE groups, the number of Claudin 11/MBP double-positive cells was significantly higher than that of Claudin 11/PDGFR-α and Claudin 11/Olig2 double-positive cells (P<0.0001). ③ Transmission electron microscopy revealed that after Claudin 11 overexpression, the myelin G-ratio in the CV+SE group was significantly improved compared with the SE group (P<0.0001). ④ The Morris water maze and Y-maze tests showed that compared with the SE group, the escape latency in the Morris water maze was significantly shortened (P=0.0212) and the spontaneous alternation rate in the Y-maze was significantly increased (P=0.0067) in the CV+SE group. ⑤ No statistically significant differences were observed in the time spent in the center zone, the percentage of entries into the center zone in the open field test, or the percentage of time spent and entries into the open arms in the elevated plus maze.

Claudin 11 overexpression attenuates SE-induced myelin damage and partially ameliorates spatial cognitive impairment, indicating its protective role against post-SE myelination deficits.