Effects of Three Different Doses of Inter-Alpha Inhibitor Proteins on Severe Hypoxia–Ischemia-Related Brain Injury in Neonatal Rats

Abstract

Hypoxia–ischemia (HI)-related brain injury is an important cause of morbidity and long-standing disability in newborns. We have previously shown that human plasma-derived inter-alpha inhibitor proteins (hIAIPs) attenuate HI-related brain injury in neonatal rats. The optimal dose of hIAIPs for their neuroprotective effects and improvement in behavioral outcomes remains to be determined. We examined the efficacy of 30, 60, or 90 mg/kg of hIAIPs administered to neonatal rats after exposure to HI for 2 h. Postnatal day 7 (P7) Wistar rats were exposed to either sham-surgery or unilateral HI (right carotid artery ligation, 2 h of 8% O2) brain injury. A placebo, 30, 60, or 90 mg/kg of hIAIPs were injected intraperitoneally at 0, 24 and 48 h after HI (n = 9–10/sex). We carried out the following behavioral analyses: P8 (righting reflex), P9 (negative geotaxis) and P10 (open-field task). Rats were humanely killed on P10 and their brains were stained with cresyl violet. Male extension/contraction responses and female righting reflex times were higher in the HI placebo groups than the sham groups. Female open-field exploration was lower in the HI placebo group than the sham group. hIAIPs attenuated these behavioral deficits. However, the magnitude of the responses did not vary by hIAIP dose. hIAIPs reduced male brain infarct volumes in a manner that correlated with improved behavioral outcomes. Increasing the hIAIP dose from 30 to 90 mg/kg did not further accentuate the hIAIP-related decreases in infarct volumes. We conclude that larger doses of hIAIPs did not provide additional benefits over the 30 mg/kg dose for behavior tasks or reductions in infarct volumes in neonatal rats after exposure to severe HI.

Inter-Alpha Inhibitor Proteins Modify the Microvasculature after Exposure to Hypoxia–Ischemia and Hypoxia in Neonatal Rats

“…The 30 mg/kg dose of hIAIPs was selected based on our previous studies showing that this dose ameliorated pathological brain injury, infarct volume, and neuroinflammation in neonatal rats 3 days after exposure to moderate HI [ 20 , 22 ]. Furthermore, we have shown that larger doses of hIAIPs (60 mg/kg and 90 mg/kg) did not provide additional benefits over the 30 mg/kg dose for reductions in infarct volumes or behavior tasks in neonatal rats after exposure to severe HI for 2 h [ 31 ]. The half-life of hIAIPs in the systemic circulation of neonatal rats is 12.4 h in sham-treated males, 9.6 h in sham-treated females, 23.1 h in HI-treated males, and 16.2 h in HI-treated female rats [ 32 ].…”

Neuroprotective efficacy of hypothermia and Inter-alpha Inhibitor Proteins after hypoxic ischemic brain injury in neonatal rats

“…The righting reflex test was conducted on P8, P9, and P10 to examine early motor coordination after exposure to HI. The procedure involved placing the rat in a supine position on a flat surface and measuring the time required for the rat to right itself to a prone position with all four paws in contact with the surface [ 25 , 26 ]. The latency to achieve the prone position was recorded in seconds (sec).…”

“…Inter-alpha inhibitor proteins (IAIPs) are naturally occurring molecules found in relatively high concentrations in human plasma [ 20 , 21 ]. These proteins exhibit important anti-inflammatory and immunomodulatory properties and have gained attention because of their beneficial effects in various conditions including sepsis, HI-related brain injury in newborns, and stroke in adult subjects [ [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] ]. Recent studies have demonstrated the potential benefits of treatment with human plasma derived IAIPs (hIAIPs) to reduce neuronal cell death and neuroinflammation in male neonatal rats after exposure to HI [ 23 , 30 ].…”

Hyaluronan hydrates and compartmentalises the CNS/PNS extracellular matrix and provides niche environments conducive to the optimisation of neuronal activity

“…Administered ITI ameliorates brain injury, prevents cell death and improves behavioural outcomes after neonatal hypoxic ischaemia in rats (Chen et al, 2020(Chen et al, , 2022Koehn et al, 2022;McCullough et al, 2021;Schuffels et al, 2020). ITI is ubiquitously expressed in brain tissues, and co-localises with neurons and astrocytes in the developing and adult human (Kim et al, 2020) and rat brain (Chen et al, 2016).…”

“…TSG‐6 is constitutively expressed in the brain and spinal cord, up‐regulated in response to inflammation and has anti‐inflammatory and immunomodulatory tissue‐protective functions in neurodegenerative diseases (Day & Milner, 2019; La Russa et al, 2023). Administered ITI ameliorates brain injury, prevents cell death and improves behavioural outcomes after neonatal hypoxic ischaemia in rats (Chen et al, 2020, 2022; Koehn et al, 2022; McCullough et al, 2021; Schuffels et al, 2020). ITI is ubiquitously expressed in brain tissues, and co‐localises with neurons and astrocytes in the developing and adult human (Kim et al, 2020) and rat brain (Chen et al, 2016).…”