Interleukin-35 exhibits protective effects in a rat model of hypoxic-ischemic encephalopathy through the inhibition of microglia-mediated inflammation

Guangliang Liu; Ming Li; Shuang Qian; Lulu Yu; Lei Qian; Xing Feng

doi:10.21037/tp-22-100

Interleukin-35 exhibits protective effects in a rat model of hypoxic-ischemic encephalopathy through the inhibition of microglia-mediated inflammation

Transl Pediatr. 2022 May;11(5):651-662. doi: 10.21037/tp-22-100.

Authors

Guangliang Liu^#^{1

2}, Ming Li^#³, Shuang Qian⁴, Lulu Yu³, Lei Qian³, Xing Feng¹

Affiliations

¹ Department of Neonatology, Children's Hospital of Soochow University, Suzhou, China.
² Department of Pediatrics, Binhai County People's Hospital, Bianhai, China.
³ Department of Laboratory Medicine, Binhai County People's Hospital, Bianhai, China.
⁴ Jiangsu Institute of Hematology, Key Laboratory of Thrombosis and Hemostasis of the Ministry of Health, The First Affiliated Hospital of Soochow University, Suzhou, China.

^# Contributed equally.

Abstract

Background: Hypoxic-ischemic encephalopathy (HIE) brain damage is related to inflammatory responses and oxidative stress. Interleukin (IL)-35 is an antioxidant and anti-inflammatory cytokine. Thus, the effect of IL-35 treatment on neonatal rats with hypoxic-ischemic brain injury was investigated.

Methods: A total of 96 7-day-old Sprague Dawley rats were randomly divided into three groups: sham group, HIE group, and IL-35 group. After left common carotid occlusion and 2.5 h hypoxia (HI injury), IL-35 (20 µg/g) was intraperitoneally (i.p.) administered to the pups. In vitro, BV2 cells were treated with or without IL-35 6 h before oxygen-glucose deprivation (OGD) insult and the microglia culture medium (MCM) was co-cultured with b.End3 cerebral vascular endothelial cells. Microglial polarization and activation were assessed by real-time quantitative polymerase chain reaction (RT-qPCR), Western blot, and enzyme-linked immunosorbent assay (ELISA). Endothelial cell dysfunction was measured by cell counting kit-8 and Western blot assays.

Results: Administration of IL-35 alleviated neurological deficiencies, decreased brain edema, ameliorated cerebral infarction, and limited M1 microglial polarization in HI-injured pups. Meanwhile, IL-35 decreased pro-inflammatory cytokines, tumor necrosis factor-α, IL-1β, and reactive oxygen species generation in OGD-induced bEnd.3 cells. Furthermore, IL-35 treatment could reverse the vascular endothelial cell injury induced by microglial polarization. Finally, IL-35 markedly suppressed the activation of hypoxia-inducible factor-1α (HIF-1α) and the nuclear factor-κB (NF-κB) signaling pathway in vivo and in vitro.

Conclusions: IL-35 relieved hypoxic-ischemic-induced brain injury and inhibited the inflammatory response by suppressing microglial polarization and activation. These results suggest that IL-35 might have potential applications for the treatment of HIE.

Keywords: Hypoxic-ischemic encephalopathy (HIE); interleukin-35 (IL-35); microglia.