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. 2024 Jul 2;21(9):1756-1768.
doi: 10.7150/ijms.97164. eCollection 2024.

Col4a2 Mutations Contribute to Infantile Epileptic Spasm Syndrome and Neuroinflammation

Affiliations

Col4a2 Mutations Contribute to Infantile Epileptic Spasm Syndrome and Neuroinflammation

Chunhui Hu et al. Int J Med Sci. .

Abstract

There are more than 70 million people worldwide living with epilepsy, with most experiencing the onset of epilepsy in childhood. Despite the availability of more than 20 anti-seizure medications, approximately 30% of epilepsy patients continue to experience unsatisfactory treatment outcomes. This situation places a heavy burden on patients' families and society. Childhood epilepsy is a significant chronic neurological disease that is closely related to genetics. Col4a2, the gene encoding the α2 chain of type IV collagen, is known to be associated with multiple diseases due to missense mutations. The Col4a2 variant of collagen type IV is associated with various phenotypes, including prenatal and neonatal intracranial hemorrhage, porencephaly, porencephaly with cataracts, focal cortical dysplasia, schizencephaly, strokes in childhood and adolescence, and sporadic delayed hemorrhagic stroke. Although epilepsy is recognized as a clinical manifestation of porencephaly, the specific mechanism of Col4a2-related epileptic phenotypes remains unclear. A total of 8 patients aged 2 years and 2 months to 18 years who were diagnosed with Col4a2-related infantile epileptic spasm syndrome were analyzed. The seizure onset age ranged from 3 to 10 months. Initial EEG results revealed hypsarrhythmia or multiple and multifocal sharp waves, spike waves, sharp slow waves, or spike slow waves. Elevated levels of the cytokines IL-1β (32.23±12.58 pg/ml) and IL-6 (45.12±16.03 pg/ml) were detected in the cerebrospinal fluid of these patients without any signs of infection. Following antiseizure treatment, decreased IL-1β and IL-6 levels in the cerebrospinal fluid were noted when seizures were under control. Furthermore, we aimed to investigate the role of Col4a2 mutations in the development of epilepsy. Through the use of immunofluorescence assays, ELISA, and Western blotting, we examined astrocyte activity and the expression of inflammatory cytokines such as IL-1β, IL-6, and TNF-α after overexpressing an unreported Col4a2 (c.1838G>T) mutant in CTX-TNA cells and primary astrocytes. We found that the levels of the inflammatory factors IL-1β, IL-6, and TNF-α were increased in both CTX-TNA cells (ELISA: p = 0.0087, p<0.001, p<0.001, respectively) and primary astrocytes (ELISA: p = 0.0275, p<0.001, p<0.001, respectively). Additionally, we conducted a preliminary investigation of the role of the JAK/STAT pathway in Col4a2 mutation-associated epilepsy. Col4a2 mutation stimulated astrocyte activation, increasing iNOS, COX-2, IL-1β, IL-6, and TNF-α levels in both CTX-TNA cells and primary astrocytes. This mutation also activated the JAK/STAT signaling pathway, leading to increased phosphorylation of JAK2 and STAT3. Treatment with the JAK/STAT inhibitor WP1066 effectively counteracted this effect in primary astrocytes and CTX-TNA cells. To date, the genes who mutations are known to cause developmental and epileptic encephalopathies (DEEs) are predominantly grouped into six subtypes according to function. Our study revealed that an unreported mutation site Col4a2Mut (c.1838G>T) of which can cause neuroinflammation, may be a type VII DEE-causing gene.

Keywords: Col4a2; astrocytes; infantile epileptic spasm syndrome; neuroinflammation.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interest exists.

Figures

Figure 1
Figure 1
Mutation of Col4a2 promotes inflammation and astrocyte activation in CTX-TNA cells. CTX-TNA cells were stimulated with LPS and transfected with the Col4a2Wt-AdV vector or the Col4a2Mut-AdV vector. (A) The fluorescence intensity of GFAP (red) was measured in 5 different groups, with 50 CTX-TNA cells per group from 3 repeated experiments. The scale bar represents 25 μm. (B) Quantitative graphs displaying the mean fluorescence intensity of the GFAP-positive cells in (A). (C-E) Enzyme-linked immunosorbent assays were used to quantify IL-1β, IL-6, and TNF-α levels in the supernatant of CTX-TNA cells from 3 repeated experiments. The figure includes results from one-way ANOVA with calculated p values. (F) Western blot analysis was performed for GFAP, IL-1β, IL-6, TNF-α, JAK2, p-JAK2, STAT3, and p-STAT3. The proteins for the western blot analysis were extracted from cell lysates. **: vs. con, p<0.01; ++: vs. LPS+NC, p<0.01; ##: vs. LPS+ Col4a2Wt, p<0.01.
Figure 2
Figure 2
Col4a2 mutation promotes inflammation and astrocyte activation by stimulating JAK/STAT signaling in CTX-TNA cells. CTX-TNA cells were stimulated with LPS and transfected with the Col4a2Wt-AdV vector or the Col4a2Mut-AdV vector or treated with WP1066 (a JAK2/STAT inhibitor). (A) The fluorescence intensity of GFAP was observed in 6 different groups (50 CTX-TNA cells per group) from 3 repeated experiments. The scale bar represents 25 μm. (B) Quantitative graphs displaying the mean fluorescence intensity of the GFAP-positive cells in (A). The figure includes the results of one-way ANOVA with calculated p values. (C) Western blot analysis of GFAP, IL-1β, IL-6, TNF-α, JAK2, p-JAK2, STAT3, and p-STAT3 was performed. The proteins for the western blot analysis were extracted from cell lysates. **: vs. con, p<0.01; ++: vs. LPS+NC, p<0.01; ##: vs. LPS+ Col4a2Wt, p<0.01; ^^: vs. LPS+ Col4a2Mut, p<0.01.
Figure 3
Figure 3
Col4a2 mutation promotes inflammation and astrocyte activation in primary astrocytes. Primary astrocytes were stimulated with LPS and transfected with either the Col4a2Wt-AdV vector or the Col4a2Mut-AdV vector. (A) The fluorescence intensity of GFAP (red) was measured in 5 different primary astrocyte groups, with 50 cells per group from 3 repeated experiments. The scale bar indicates 25 μm. (B) Quantitative graphs displaying the mean fluorescence intensity of the GFAP-positive cells in (A). (C-E) Enzyme-linked immunosorbent assays were used to measure IL-1β, IL-6, and TNF-α levels in primary astrocyte supernatants from 3 repeated experiments. The figure includes one-way ANOVA results with corresponding p values. (F) Western blot analysis was performed for GFAP, IL-1β, IL-6, TNF-α, JAK2, p-JAK2, STAT3, and p-STAT3. The proteins for the western blot analysis were extracted from cell lysates. **: vs. control, p<0.01; ++: vs. LPS+NC, p<0.01; ##: vs. LPS+ Col4a2Wt, p<0.01.
Figure 4
Figure 4
Col4a2 mutation promotes inflammation and astrocyte activation by stimulating JAK/STAT signaling in primary astrocytes. Primary astrocytes were stimulated with LPS and transfected with the Col4a2Wt-AdV vector or the Col4a2Mut-AdV vector or treated with WP1066 (a JAK2/STAT inhibitor). (A) The fluorescence intensity of GFAP in six different primary astrocyte groups (50 cells per group) from 3 repeated experiments is shown. The scale bar represents 25 μm. (B) Quantitative graphs displaying the mean fluorescence intensity of the GFAP-positive cells in (A). One-way ANOVA with calculated p values is presented in the figure. (C) Western blot analysis was conducted for GFAP, IL-1β, IL-6, TNF-α, JAK2, p-JAK2, STAT3, and p-STAT3. The proteins for the western blot analysis were extracted from cell lysates. **: vs. control, p<0.01; ++: vs. LPS+NC, p<0.01; ##: vs. LPS+ Col4a2Wt, p<0.01; ^^: vs. LPS+ Col4a2Mut, p<0.01.

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