Pharmacokinetics of Inter-Alpha Inhibitor Proteins and Effects on Hemostasis After Hypoxic-Ischemic Brain Injury in Neonatal Rats

Abstract

Background: Hypoxic-ischemic (HI) brain injury is a leading cause of long-term neurodevelopmental morbidities in neonates. Human plasma-derived Inter-Alpha Inhibitor Proteins (hIAIPs) are neuroprotective after HI brain injury in neonatal rats. The light chain (bikunin) of hIAIPs inhibits proteases involved in coagulation of blood. Newborns exposed to HI can be at risk for significant bleeding in the brain and other organs. Objective: The objectives of the present study were to assess the pharmacokinetics (PK) and duration of bleeding after intraperitoneal (IP) administration of hIAIPs in HI-exposed male and female neonatal rats. Methods: HI was induced with the Rice-Vannucci method in postnatal (P) day-7 rats. After right common carotid artery ligation, rats were exposed to 90 min of 8% oxygen. hIAIPs (30 mg/kg, IP) were given immediately after Sham or HI exposure in the PK study and serum was collected 1, 6, 12, 24, or 36 h after the injections. Serum hIAIP concentrations were measured with a competitive ELISA. ADAPT5 software was used to fit the pooled PK data considering first-order absorption and disposition. hIAIPs (60 mg/kg, IP) were given in the bleeding time studies at 0, 24 and 48 h after HI with tail bleeding times measured 72 h after HI. Results: IP administration yielded significant systemic exposure to hIAIPs with PK being affected markedly including primarily faster absorption and reduced elimination as a result of HI and modestly because of sex related differences. In addition, hIAIP administration did not affect bleeding times after HI. Conclusion: These results will help to inform hIAIP dosing regimen schedules in studies of neuroprotection in neonates exposed to HI.

Novel Neuroprotective Agents to Treat Neonatal Hypoxic-Ischemic Encephalopathy: Inter-Alpha Inhibitor Proteins

“…Thus far, intraperitoneal doses 30 and 60 mg/kg/day of IAIPs have been investigated in neonatal rodents exposed to HI and adult rodents exposed to LPS [40,[63][64][65][66][67][68]71]. Recent pharmacokinetic analysis has shown that the plasma half-life of IAIPs is 9-12 h in control neonatal rats and 16-23 h in neonatal rats exposed to HI [41]. These results provide some evidence to support separating doses by 24 h in neonates exposed to HI-related insults.…”

“…Highly efficient extraction and purification processes from human plasma have been successfully developed because both major forms of IAIPs (IaI and PaI) are found in relatively high concentrations in human blood. Both the 250 kDa IaI and 125 kDa PaI have been co-purified and isolated together during chromatographic separation on anion-exchange and proprietary affinity synthetic mimetic columns [40][41][42]. The highly purified IAIPs are biologically active as assessed by quantitatively measuring the ability of the proteins to inhibit the hydrolysis of a chromogenic trypsin substrate and monitoring the rate of decrease on a spectrometer [43].…”

“…However, due to its short plasma half-life (<10 min), continuous intravenous administration would be required for extended treatments [54]. Pharmacokinetic analysis of IAIPs in neonatal HI models has shown a much longer half-life of 16-23 h [41]. The complete molecular form of IAIPs may be more appropriate agents to treat neonatal subjects exposed to HI, in which brain injury evolves over a period of days to weeks [4,55].…”

“…It also remains possible that doses lower than 30 mg/kg may also be efficacious or that a higher dose may be more effective at protecting the brain from HI-related insults. Safety analysis has suggested that 60 mg/kg of IAIPs do not produce adverse effects on body weight or bleeding times in neonatal rats exposed to HI, suggesting that high doses could be considered to improve efficacy [41]. Thirty or 45 mg/kg doses provided similar efficacy in neonatal rodents exposed to sepsis resulting in markedly improved survival, although doses of 15 mg/kg were not as effective [35].…”

Exogenous inter-α inhibitor proteins prevent cell death and improve ischemic stroke outcomes in mice

“…The free light chain, or bikunin, has been shown to decrease infarct size and limit neuronal apoptosis in adult animals after cerebral ischemia (27,28). However, due to high renal clearance, bikunin has a very short half-life (3-15 minutes) (29) when compared with the plasma-derived IAIP complexes (10-12 hours) (30). In addition, the role of the heavy chains in this protein family has been largely overlooked.…”