Exogenous inter-α inhibitor proteins prevent cell death and improve ischemic stroke outcomes in mice
Louise D. McCullough, Meaghan Roy-O’Reilly, Yun-Ju Lai, Anthony Patrizz, Yan Xu, Juneyoung Lee, Aleah Holmes, Daniel C. Kraushaar, Anjali Chauhan, Lauren H. Sansing, Barbara S. Stonestreet, Liang Zhu, Julia Kofler, Yow-Pin Lim, Venugopal Reddy Venna
Louise D. McCullough, Meaghan Roy-O’Reilly, Yun-Ju Lai, Anthony Patrizz, Yan Xu, Juneyoung Lee, Aleah Holmes, Daniel C. Kraushaar, Anjali Chauhan, Lauren H. Sansing, Barbara S. Stonestreet, Liang Zhu, Julia Kofler, Yow-Pin Lim, Venugopal Reddy Venna
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Research Article Inflammation Neuroscience

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

Abstract

Inter-α inhibitor proteins (IAIPs) are a family of endogenous plasma and extracellular matrix molecules. IAIPs suppress proinflammatory cytokines, limit excess complement activation, and bind extracellular histones to form IAIP-histone complexes, leading to neutralization of histone-associated cytotoxicity in models of sepsis. Many of these detrimental processes also play critical roles in the pathophysiology of ischemic stroke. In this study, we first assessed the clinical relevance of IAIPs in stroke and then tested the therapeutic efficacy of exogenous IAIPs in several experimental stroke models. IAIP levels were reduced in both ischemic stroke patients and in mice subjected to experimental ischemic stroke when compared with controls. Post-stroke administration of IAIP significantly improved stroke outcomes across multiple stroke models, even when given 6 hours after stroke onset. Importantly, the beneficial effects of delayed IAIP treatment were observed in both young and aged mice. Using targeted gene expression analysis, we identified a receptor for complement activation, C5aR1, that was highly suppressed in both the blood and brain of IAIP-treated animals. Subsequent experiments using C5aR1-knockout mice demonstrated that the beneficial effects of IAIPs are mediated in part by C5aR1. These results indicate that IAIP is a potential therapeutic candidate for the treatment of ischemic stroke.

Authors

Louise D. McCullough, Meaghan Roy-O’Reilly, Yun-Ju Lai, Anthony Patrizz, Yan Xu, Juneyoung Lee, Aleah Holmes, Daniel C. Kraushaar, Anjali Chauhan, Lauren H. Sansing, Barbara S. Stonestreet, Liang Zhu, Julia Kofler, Yow-Pin Lim, Venugopal Reddy Venna

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Figure 5

Delayed exogenous IAIP treatment reduces post-stroke mortality and improves long-term recovery.

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Delayed exogenous IAIP treatment reduces post-stroke mortality and impro...
(A) IAIP-treated animals had improved mortality rates compared with vehicle-treated animals by day 15; no additional animals died between days 15 and 30 (*P = 0.0347, log-rank test). (B) IAIP treatment significantly reduced rotational bias in the corner test versus vehicle at day 7 (*P = 0.0491), day 14 (*P = 0.0153), and day 21 (**P = 0.0099) (repeated-measures ANOVA adjusted for multiple testing). IAIP-treated mice recovered by post-stroke day 28 compared with shams; vehicle-treated mice remained significantly impaired compared with shams (P = 0.0074). (C) IAIP treatment significantly improved stroke-induced cognitive deficits as measured by the novel object recognition test in young male mice at post-stroke day 28 (*P = 0.041, 2-way ANOVA). (D) Mice treated with IAIP had significantly better learning ability compared with the vehicle group during training sessions from day 22 to day 25 (day 23, ****P < 0.0001; day 25, ****P < 0.0001; repeated-measures 2-way ANOVA adjusted for multiple testing). (E) Representative images of Barnes maze mouse movement tracking. (F) Stroke mice treated with IAIP had improved memory retention at day 27 compared with the vehicle group (****P < 0.0001, 2-way ANOVA), with no significant difference in sham groups. (G) Representative Nissl-stained sections of CA1 region of hippocampus. Scale bar: 25 μm. (H) Quantification of neuronal counts demonstrated significant neuronal loss after stroke (***P = 0.0009); IAIP treatment significantly reduced neuronal loss (*P = 0.0316) compared with vehicle, normalized and presented relative to sham, by 2-way ANOVA adjusted for multiple testing. (I) IAIP significantly improved recovery after distal stroke in aged male mice versus vehicle at day 7 (**P = 0.0032), day 14 (***P = 0.0002), and day 21 (*P = 0.0344) (repeated-measures ANOVA adjusted for multiple testing).