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Activated protein C reduces endotoxin-induced white matter injury in the developing rat brain
Didem Cemile Yesilirmak1, Abdullah Kumral, Huseyin Baskin
1Department of Pediatrics, School of Medicine, Dokuz Eylul, University, Inciralti, 35340, Izmir, Turkey.
Insights
Activated protein C (APC) reduces white matter injury (WMI) and inflammation in a rat model of preterm infant brain injury. This suggests APC may help prevent periventricular leukomalacia (PVL) and cerebral palsy in at-risk infants.
Area of Science:
- Neuroscience
- Developmental Biology
- Pharmacology
Background:
- Periventricular leukomalacia (PVL) is a major cause of brain injury in premature infants, often leading to cerebral palsy.
- The exact causes of PVL are complex, involving factors like infection, inflammation, and blood flow issues.
- Activated protein C (APC) has known anti-inflammatory, anti-apoptotic, and cytoprotective properties.
Purpose of the Study:
- To investigate the potential of activated protein C (APC) in preventing white matter injury (WMI) in a rat model simulating human PVL.
- To assess the anti-inflammatory effects of APC against endotoxin-induced brain injury in developing rat brains.
Main Methods:
- An animal model was used, administering lipopolysaccharide (LPS) to pregnant rats to induce endotoxin exposure.
- Recombinant human activated protein C (rhAPC) was administered to assess its protective effects against LPS-induced WMI.
- Cell death (TUNEL staining) and myelin basic protein (MBP) expression were analyzed in neonatal rat brains.
- Inflammatory cytokine levels (TNF-alpha, IL-6) were measured using ELISA.
Main Results:
- APC treatment significantly reduced cell death in the white matter of LPS-exposed rat pups.
- APC administration attenuated the hypomyelination typically induced by LPS exposure.
- APC effectively reduced the protein expression of inflammatory cytokines (TNF-alpha, IL-6) in neonatal rat brains.
- Both prenatal and postnatal administration of APC demonstrated protective and anti-inflammatory effects.
Conclusions:
- Activated protein C (APC) shows significant neuroprotective and anti-inflammatory effects against endotoxin-induced white matter injury in developing rat brains.
- These findings support the potential therapeutic use of APC to mitigate the risk of PVL and subsequent cerebral palsy in preterm infants exposed to infection.
- APC may be a promising treatment strategy for pregnant women and preterm infants facing risks associated with maternal or placental infections.
Abstract:
Periventricular leukomalacia (PVL), the dominant form of brain injury in premature infants, is characterized by white matter injury (WMI) and is associated with cerebral palsy. The pathogenesis of PVL is complex and likely involves ischemia/reperfusion, free radical formation, excitotoxicity, impaired regulation of cerebral blood flow, a procoagulant state, and inflammatory mechanisms associated with maternal and/or fetal infection. Using an established animal model of human PVL, we investigated whether activated protein C (APC), an anti-coagulant factor with anti-inflammatory, anti-apoptotic, anti-oxidant, and cytoprotective activities, could reduce endotoxin-induced WMI in the developing rat brain. Intraperitoneal injections of lipopolysaccharide (LPS) (0.5 mg/kg body weight) were given at embryonic days 18 (E18) and 19 (E19) to pregnant Sprague-Dawley rats; control rats were injected with sterile saline. A single intravenous injection of recombinant human (rh) APC (0.2 mg /kg body weight) was given to pregnant rats following the second LPS dose on embryonic day 19 (E19). Reduced cell death in white matter and hypomyelination were shown on TUNEL and myelin basic protein (MBP) staining, respectively, on late postnatal days (P7) in APC-treated groups. There were significantly fewer TUNEL+nuclei in the periventricular WM in the APC+LPS group than in the untreated LPS group. Compared to the APC+LPS and control group, MBP expression was weak in the LPS group on P7, indicating endotoxin-induced hypomyelination in the developing rat brain. APC attenuated the LPS-induced protein expression of inflammatory cytokines, tumor necrosis factor-alpha, and interleukin-6, as evaluated by ELISA in neonatal rat brains. A single intraperitoneal injection of rhAPC (0.2 mg/kg body weight) to neonatal rats on P1 also had similar protective and anti-inflammatory effects against maternally administered LPS. Collectively, these data support the hypothesis that APC may provide protection against an endotoxin-evoked inflammatory response and WMI in the developing rat brain. Moreover, our results suggest that the possible use of APC in treatment of preterm infants and pregnant women with maternal or placental infection may minimize the risk of PVL and cerebral palsy.
