2026-06-26 | HMGB1-TLR4 signaling-mediated neuroinflammation contributes to the pathogenesis of infantile epileptic spasms syndrome in rats
Background: Infantile epileptic spasm syndrome (IESS) is a severe age-dependent epileptic encephalopathy in infancy with poor prognosis and unclear pathogenesis. Neuroinflammation plays a pivotal role in epileptogenesis, and the high-mobility group box 1 protein (HMGB1)-Toll-like receptor 4 (TLR4) axis acts as a core mediator of neuroinflammation. However, its specific role in IESS remains elusive. Objective: This study aimed to explore the HMGB1-TLR4-mediated neuroinflammatory mechanism in a rat model of IESS induced by prenatal stress combined with NMDA, and to evaluate the effects of anti-HMGB1 neutralizing antibody and adrenocorticotropic hormone (ACTH) on epileptic seizures and neuroinflammation, so as to provide novel therapeutic targets for clinical practice. Methods: Pregnant Sprague-Dawley rats were randomly divided into prenatal stress (PS) and non-prenatal stress (NPS) groups. PS rats received cold water immersion and hot air drying, while NPS rats were reared normally. On postnatal day 12 (P12), offspring in the PS group were intraperitoneally injected with NMDA to establish the IESS model, and the NPS group was assigned to blank control (BC) and negative control (NC) subgroups. Model rats were randomly divided into ACTH, anti-HMGB1, ACTH+anti-HMGB1, normal saline, and untreated groups. After intervention on P13, NMDA was re-administered, and seizure latency and severity score were recorded. At the end of the experiment, the expression of HMGB1 and TLR4 in brain tissue was detected, HMGB1 co-localization was observed, and the levels of iNOS, Arg1 and cytokines (IL-1β, IL-2R, IL-8, TNF-α) were measured. Results: Prenatal stress combined with NMDA successfully established a stable IESS model in young rats. The expression of HMGB1, TLR4, iNOS, IL-1β, IL-2R, IL-8 and TNF-α was significantly upregulated, while Arg1 was markedly downregulated. Treatment with ACTH, anti-HMGB1, and their combination prolonged seizure latency, reduced seizure severity, downregulated HMGB1 and TLR4 expression, suppressed HMGB1 levels in neurons, astrocytes and activated microglia, inhibited iNOS and proinflammatory cytokines, and promoted Arg1 expression, with the combined intervention showing the optimal efficacy. Conclusion: Prenatal stress combined with NMDA activates the HMGB1/TLR4 pathway and neuroinflammation in IESS rats. ACTH and anti-HMGB1, alone or in combination, alleviate neuroinflammation by inhibiting this pathway to ameliorate IESS, and the combined therapy yields the best therapeutic effect.
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2026-05-20 | Blockade of Corticotropin-Releasing Hormone Receptor 1 Receptors in the Arcuate Nucleus May Effectively Treat Infantile Epileptic Spasms Syndrome
Targeting Corticotropin-Releasing Hormone Receptor 1 Signaling in Experimental Infantile Epileptic Spasms Syndrome: Evidence for Route-Dependent Efficacy. Chachua T, Yum MS, Chern CR, Vieira K, Velíšková J, Velíšek L. Targeting CRHR1 Signaling in Experimental Infantile Epileptic Spasms Syndrome: Evidence for Route-Dependent Efficacy. Children (Basel). 2026 Jan 14;13(1):125. doi: 10.3390/children13010125. PMID: 41597133; PMCID: PMC12840083. Background/Objectives: Infantile epileptic spasms syndrome (IESS) is a severe epilepsy of infancy. Corticotropin (ACTH) and vigabatrin are the only FDA-approved therapies. The efficacy of ACTH together with the strong convulsant effects of corticotropin-releasing hormone (CRH) suggests that excess CRH, secondary to impaired ACTH feedback, may contribute to spasms. We therefore hypothesized that CRH receptor 1 (CRHR1) antagonists would suppress spasms in a route- and drug-dependent manner. Methods: Using our validated rat model of IESS, in which prenatal priming with betamethasone was followed by postnatal triggering of spasms with N-methyl-D-aspartic acid (NMDA), we tested two CRHR1 antagonists, CP376395 and SN003, delivered intracranially (via intracerebroventricular or intraparenchymal infusion) or systemically. Results: Intracerebroventricular infusion of both antagonists suppressed spasms, with CP376395 providing more consistent effects. Intraparenchymal administration into the hypothalamic arcuate nucleus also reduced spasms, whereas misses into the mammillary bodies were ineffective, highlighting site specificity. Systemic administration yielded divergent results: SN003 robustly suppressed spasms, whereas CP376395 unexpectedly exacerbated them. No sex differences were observed. Conclusions: These findings demonstrate that CRHR1 blockade modifies experimental spasms in a route- and drug-specific manner and implicates discrete hypothalamic circuits, particularly those including the arcuate nucleus, in spasm generation. The divergent systemic responses between CP376395 and SN003 likely reflect differences in CRHR1 engagement (competitive and non-competitive antagonism, respectively) as well as differences in binding properties that may include differential network interactions beyond local CRH signaling or duration of receptor occupancy. In conclusion, SN003 may be a better option than CP376395 for further development as a CRHR1-targeted therapy pending additional pharmacokinetic/pharmacodynamic studies. Further work should explore dosing paradigms of CP376395 to determine if a therapeutic range for CP376395 exists.
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2026-05-18 | Clinical application of HMGB1-TLR4 signaling pathway-mediated neuroinflammatory markers in infantile epileptic spasms syndrome.
Infantile epileptic spasms syndrome (IESS) is a severe age-specific epileptic encephalopathy with unclear pathogenesis, and neuroinflammation is involved in its progression. The HMGB1-TLR4 signaling pathway, a key neuroinflammatory mediator in various epilepsies, has not been studied for its role and clinical biomarker potential in IESS. A retrospective study included 66 IESS patients treated with a modified prednisone regimen and 53 age-matched healthy controls. Serum HMGB1, TLR4, IL-1β, IL-2, IL-2R, IL-8 and TNF-α were detected by ELISA/chemiluminescent immunoassay in IESS patients (pre- and 2-week post-treatment) and controls; clinical data were collected via electronic medical records and follow-up. IESS patients had significantly higher serum HMGB1, TLR4, IL-2, IL-2R, IL-8 and TNF-α than controls (P < 0.05; no IL-1β difference, P>0.05), and these elevated indicators decreased markedly post-treatment (P < 0.05). Logistic regression showed identified etiology and focal seizures were risk factors for short-term prednisone ineffectiveness, while ΔPre-Post HMGB1 was a protective factor (P < 0.05). Long-term follow-up (≥18 months) found identified etiology to be a risk factor for uncontrolled epilepsy and poor neurodevelopment (P < 0.05); early spasm remission and long-term seizure control were protective factors for neurodevelopment (P < 0.05). The HMGB1-TLR4 pathway mediates neuroinflammation in IESS pathogenesis and may serve as a therapeutic target. A high ΔPre-Post HMGB1 level was identified as a protective factor against short-term treatment failure of prednisone, indicating that dynamic monitoring of HMGB1 has clinical value for predicting short-term treatment responses to prednisone, though it does not predict long-term seizure control or neurodevelopmental outcomes. Identified etiology is a common risk factor for poor IESS outcomes, highlighting the importance of early etiological screening and sustained seizure control for IESS management.
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