Regulatory mechanisms of temporal microglia phenotype expression in a neonatal rat model of infection-sensitized hypoxic ischemic brain injury

围产期窒息是全球儿童死亡的主要原因之一，描述的是出生前、出生期间或出生后不久的缺氧和血流不足。它可以影响所有的器官系统，但最可怕的结果是，主要影响新生儿大脑的是缺氧缺血性脑病(HIE)，通常会导致死亡或在以后的生活中出现严重的发病率。尽管治疗性低温(TH)已经成为HIE的标准治疗方法，但大约50%的降温新生儿仍然死亡或发展为严重残疾。早期识别这些无应答者还不可能，但迫切需要，因为他们可能从额外的治疗选择中受益。围产期感染增加了对缺氧缺血性损伤的易感性，并对受影响的新生儿的预后产生了负面影响。我们已经建立了一种感染敏感型缺氧缺血性脑损伤的动物模型(双重打击模型)，并表明在该模型中这不是一个可行的治疗选择，这是一组无反应者的特征。这种双重打击模型使我们有机会在一组确定的无反应者中调查潜在的机制。我们已经证明，在我们的双重打击模型中，小胶质细胞是关键角色，并有助于脑损伤。由于双重打击的相互作用和调控尚不清楚，本项目旨在描述在我们的双重打击致敏的新生大鼠缺氧缺血性脑损伤模型中，小胶质细胞激活和不同表型表达的调控机制。随着时间的推移，我们将关注microRNAs在小胶质细胞调控和表型表达中的作用。此外，在我们的双重打击模型中，我们将研究NLRP3炎症体的作用，它在小胶质细胞激活过程中的影响，它被miRNAs调控，以及它对脑损伤严重程度的影响。最后，我们将研究额外的神经保护治疗(促红细胞生成素)在我们的双重打击模型中的效力，描述其对小胶质细胞表型激活的影响和途径。其目的是开发强大的生物标记物和治疗靶点，将在临床研究中进行测试，及早识别对治疗性低温无反应者。

Perinatal asphyxia, describing the lack of oxygen and blood flow before, during, or just after birth, is one of the leading causes of global child death. It can affect all organ systems, however the most frightened resulting condition, predominantly affecting the newborn brain, is hypoxic ischemic encephalopathy (HIE) often resulting in mortality or significant morbidity in later life. Even though therapeutic hypothermia (TH) has become standard treatment for HIE, around 50% of cooled newborns still die or develop severe disability. Early identification of these non-responders is not possible yet, but urgently needed, as they might benefit from additional treatment options. Perinatal infection increases the vulnerability to hypoxic-ischemic injuries and negatively influences the prognosis of affected newborns. We have developed an animal model of infection-sensitized hypoxic-ischemic brain injury (double-hit model) and showed that TH is not a viable treatment option in this model, characterizing one group of non-responders. This double-hit model gives us the opportunity to investigate the underlying mechanisms in a defined group of non-responders. We have shown that microglia cells are key players in our double-hit model and contribute to brain injury. As the interaction and regulation of the double-hit is not known yet, this project aims to describe the regulatory mechanisms responsible for microglia activation and different microglia phenotype expression in our double-hit model of inflammation-sensitized hypoxic-ischemic brain injury in newborn rats. We will focus on the role of micro-RNAs in microglia modulation and phenotype expression over time. Additionally, we will investigate the role of the NLRP3 inflammasome, its impact during microglia activation, its regulation by miRNAs and its impact on severity of brain injury in our double-hit model. Last, we will investigate the potency of an additional neuroprotective treatment (Erythropoietin) in our double-hit model, describing its influence and pathway on microglia phenotype activation. The aim is to develop robust biomarkers and therapeutic targets, which will be tested in clinical studies, early identifying non-responders to therapeutic hypothermia.