Shah Tushar A, Pallera Haree K, Kaszowski Cortney L, Bass William Thomas, Lattanzio Frank A
Department of Pediatrics, Eastern Virginia Medical School, Norfolk, VA, United States.
Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA, United States.
Front Neurosci. 2021 Feb 12;15:616734. doi: 10.3389/fnins.2021.616734. eCollection 2021.
Complement activation is instrumental in the pathogenesis of Hypoxic-ischemic encephalopathy (HIE), a significant cause of neonatal mortality and disability worldwide. Therapeutic hypothermia (HT), the only available treatment for HIE, only modestly improves outcomes. Complement modulation as a therapeutic adjunct to HT has been considered, but is challenging due to the wide-ranging role of the complement system in neuroinflammation, homeostasis and neurogenesis in the developing brain. We sought to identify potential therapeutic targets by measuring the impact of treatment with HT on complement effector expression in neurons and glia in neonatal HIE, with particular emphasis on the interactions between microglia and C1q.
The Vannucci model was used to induce HIE in term-equivalent rat pups. At P10-12, pups were randomly assigned to three different treatment groups: Sham (control), normothermia (NT), and hypothermia (HT) treatment. Local and systemic complement expression and neuronal apoptosis were measured by ELISA, TUNEL and immunofluorescence labeling, and differences compared between groups.
Treatment with HT is associated with decreased systemic and microglial expression of C1q, decreased systemic C5a levels, and decreased microglial and neuronal deposition of C3 and C9. The effect of HT on cytokines was variable with decreased expression of pro and anti-inflammatory effectors. HT treatment was associated with decreased C1q binding on cells undergoing apoptosis.
Our data demonstrate the extreme complexity of the immune response in neonatal HIE. We propose modulation of downstream effectors C3a and C5a as a therapeutic adjunct to HT to enhance neuroprotection in the developing brain.
补体激活在缺氧缺血性脑病（HIE）的发病机制中起作用，HIE是全球新生儿死亡和残疾的一个重要原因。治疗性低温（HT）是HIE唯一可用的治疗方法，但其只能适度改善预后。补体调节作为HT的辅助治疗方法已被考虑，但由于补体系统在发育中大脑的神经炎症、内环境稳态和神经发生中具有广泛作用，因此具有挑战性。我们试图通过测量HT治疗对新生儿HIE中神经元和神经胶质细胞补体效应物表达的影响来确定潜在的治疗靶点，特别强调小胶质细胞与C1q之间的相互作用。
采用Vannucci模型在足月等效大鼠幼崽中诱导HIE。在出生后第10 - 12天，将幼崽随机分为三个不同的治疗组：假手术组（对照组）、正常体温组（NT）和低温治疗组（HT）。通过酶联免疫吸附测定（ELISA）、末端脱氧核苷酸转移酶介导的缺口末端标记法（TUNEL）和免疫荧光标记测量局部和全身补体表达以及神经元凋亡，并比较组间差异。
HT治疗与全身和小胶质细胞C1q表达降低、全身C5a水平降低以及小胶质细胞和神经元C3和C9沉积减少有关。HT对细胞因子的影响是可变的，促炎和抗炎效应物的表达均降低。HT治疗与凋亡细胞上C1q结合减少有关。
我们的数据证明了新生儿HIE免疫反应的极端复杂性。我们建议调节下游效应物C3a和C5a作为HT的辅助治疗方法，以增强发育中大脑的神经保护作用。
