Publicação
Peripheral immune response and its epigenetic modulation in human refractory epilepsy: a preliminary study
| Resumo: | Epilepsy isa chronic neurological disorder that affects 70 million people worldwide. In adults, Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) is the most common refractory epilepsy, with over 80% of patients’ refractory to pharmacological treatment. Inflammation is a recognized epilepsy hallmark and exacerbated neuroinflammation has been described in all epileptogenic stages. In response to neuronal damage, glial cells and endothelial cells release pro-inflammatory cytokines, activating the NF-kB pathways, ultimately leading to the expression of more inflammatory genes, such as Interleukin-1β (IL-1β). Although initially it is beneficial, when exacerbated it can become detrimental, with studies reporting an association between IL-1β levels and seizure generation, in the hippocampus of patients with epilepsy. During neuroinflammation, monocytes can infiltrate the central nervous system (CNS). Recent research has identified a specific subpopulation of monocytes, called disease inflammatory macrophages (DIMs), which are characterized by overexpression of pro-inflammatory cytokines. DIMs were found expanded in epilepsy and are thought to contribute to brain inflammation by regulating cytokine expression. Additionally, dysregulated cytokines levels have been described in serum of patients with epilepsy. Despite, the real contribution of peripheral immune cells in epilepsy has yet to be determined. This thesis aims to study the roles of inflammation and epigenetic modulation in MTLE-HS. It questions whether the dysregulated inflammatory response in the brains of these patients is also reflected in their peripheral immune system or if their immune cells exhibit an altered response to stimuli. The primary focus is the analysis of the inflammatory response of peripheral monocytes through the miRNA levels quantification of key mediators involved in IL-1β synthesis, including P2X7R, TLR4, IL-1β, and NF-kB. Additionally, inflammation-associated miRs-146a and miR-22 will be quantified in both non-stimulated and LPS-stimulated conditions. As a secondary objective, the study aims to analyze the epigenetic modulation of the immune response in MTLE-HS patients. This involves quantifying epilepsy-associated miRNAs, such as miR-146a, miR-155, miR-132, and miR-134, in the serum of MTLE-HS patients and healthy controls. The potential diagnostic and prognostic value of these miRNAs will also be assessed. In LPS-stimulated conditions an increase of miR-146a was reported in Epileptic patients (EP)- derived monocytes comparing to non-stimulated monocytes (p <0.05). The same wasn’t verified in the control group, suggesting an altered activation towards an inflammatory stimulus in patients with epilepsy. The expression of pro-inflammatory mediators, in circulating monocytes, presented no significant differences between patients and controls. Circulating miR-134 levels were higher in patients comparing to controls (p<0.05), although its diagnostic value was low (AUC = 0.633). miR-132 exhibited higher levels in patients without a history of febrile seizures, suggesting its potential role in the mechanisms involved in the progression of disease (p<0.05). Although not statistically significant miR-146a levels were higher in patients with MTLE-HS than in controls. No other significant differences were observed. In conclusion, the results suggest that monocytes from patients with MTLE-HS are more prone to produce a dysregulated inflammatory response upon stimulation. Although the diagnostic/prognostic biomarker panel did not exhibit strong statistical power for clinical use, it highlighted the potential importance of miR-134 and miR-132, which could provide insights into the dysregulated mechanisms in epilepsy and serve as promising treatment targets. Since this is a preliminary study, future research should focus on characterizing molecular and phenotypically the activated monocytes. Additionally, quantifying the response of other immune cells such as macrophages and microglia is essential for a comprehensive understanding of the immune response in epilepsy and identifying potential triggers for the excessive inflammation observed in epilepsy. |
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| Autores principais: | Santos, Cristina Alexandra Alves dos |
| Assunto: | Epilepsy MTLE-HS Inflammation CNS Peripheral Immune Response MiRNAs Cytokines Monocytes |
| Ano: | 2023 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | Epilepsy isa chronic neurological disorder that affects 70 million people worldwide. In adults, Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) is the most common refractory epilepsy, with over 80% of patients’ refractory to pharmacological treatment. Inflammation is a recognized epilepsy hallmark and exacerbated neuroinflammation has been described in all epileptogenic stages. In response to neuronal damage, glial cells and endothelial cells release pro-inflammatory cytokines, activating the NF-kB pathways, ultimately leading to the expression of more inflammatory genes, such as Interleukin-1β (IL-1β). Although initially it is beneficial, when exacerbated it can become detrimental, with studies reporting an association between IL-1β levels and seizure generation, in the hippocampus of patients with epilepsy. During neuroinflammation, monocytes can infiltrate the central nervous system (CNS). Recent research has identified a specific subpopulation of monocytes, called disease inflammatory macrophages (DIMs), which are characterized by overexpression of pro-inflammatory cytokines. DIMs were found expanded in epilepsy and are thought to contribute to brain inflammation by regulating cytokine expression. Additionally, dysregulated cytokines levels have been described in serum of patients with epilepsy. Despite, the real contribution of peripheral immune cells in epilepsy has yet to be determined. This thesis aims to study the roles of inflammation and epigenetic modulation in MTLE-HS. It questions whether the dysregulated inflammatory response in the brains of these patients is also reflected in their peripheral immune system or if their immune cells exhibit an altered response to stimuli. The primary focus is the analysis of the inflammatory response of peripheral monocytes through the miRNA levels quantification of key mediators involved in IL-1β synthesis, including P2X7R, TLR4, IL-1β, and NF-kB. Additionally, inflammation-associated miRs-146a and miR-22 will be quantified in both non-stimulated and LPS-stimulated conditions. As a secondary objective, the study aims to analyze the epigenetic modulation of the immune response in MTLE-HS patients. This involves quantifying epilepsy-associated miRNAs, such as miR-146a, miR-155, miR-132, and miR-134, in the serum of MTLE-HS patients and healthy controls. The potential diagnostic and prognostic value of these miRNAs will also be assessed. In LPS-stimulated conditions an increase of miR-146a was reported in Epileptic patients (EP)- derived monocytes comparing to non-stimulated monocytes (p <0.05). The same wasn’t verified in the control group, suggesting an altered activation towards an inflammatory stimulus in patients with epilepsy. The expression of pro-inflammatory mediators, in circulating monocytes, presented no significant differences between patients and controls. Circulating miR-134 levels were higher in patients comparing to controls (p<0.05), although its diagnostic value was low (AUC = 0.633). miR-132 exhibited higher levels in patients without a history of febrile seizures, suggesting its potential role in the mechanisms involved in the progression of disease (p<0.05). Although not statistically significant miR-146a levels were higher in patients with MTLE-HS than in controls. No other significant differences were observed. In conclusion, the results suggest that monocytes from patients with MTLE-HS are more prone to produce a dysregulated inflammatory response upon stimulation. Although the diagnostic/prognostic biomarker panel did not exhibit strong statistical power for clinical use, it highlighted the potential importance of miR-134 and miR-132, which could provide insights into the dysregulated mechanisms in epilepsy and serve as promising treatment targets. Since this is a preliminary study, future research should focus on characterizing molecular and phenotypically the activated monocytes. Additionally, quantifying the response of other immune cells such as macrophages and microglia is essential for a comprehensive understanding of the immune response in epilepsy and identifying potential triggers for the excessive inflammation observed in epilepsy. |
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