Interleukin-10 improves stroke outcome by controlling the detrimental Interleukin-17A response

Abstract

Background Lymphocytes have dichotomous functions in ischemic stroke. Regulatory T cells are protective, while IL-17A from innate lymphocytes promotes the infarct growth. With recent advances of T cell-subtype specific transgenic mouse models it now has become possible to study the complex interplay of T cell subpopulations in ischemic stroke. Methods In a murine model of experimental stroke we analyzed the effects of IL-10 on the functional outcome for up to 14 days post-ischemia and defined the source of IL-10 in ischemic brains based on immunohistochemistry, flow cytometry, and bone-marrow chimeric mice. We used neutralizing IL-17A antibodies, intrathecal IL-10 injections, and transgenic mouse models which harbor a deletion of the IL-10R on distinct T cell subpopulations to further explore the interplay between IL-10 and IL-17A pathways in the ischemic brain. Results We demonstrate that IL-10 deficient mice exhibit significantly increased infarct sizes on days 3 and 7 and enlarged brain atrophy and impaired neurological outcome on day 14 following tMCAO. In ischemic brains IL-10 producing immune cells included regulatory T cells, macrophages, and microglia. Neutralization of IL-17A following stroke reversed the worse outcome in IL-10 deficient mice and intracerebral treatment with recombinant IL-10 revealed that IL-10 controlled IL-17A positive lymphocytes in ischemic brains. Importantly, IL-10 acted differentially on αβ and γδ T cells. IL-17A producing CD4+ αβ T cells were directly controlled via their IL-10-receptor (IL-10R), whereas IL-10 by itself had no direct effect on the IL-17A production in γδ T cells. The control of the IL-17A production in γδ T cells depended on an intact IL10R signaling in regulatory T cells (Tregs). Conclusions Taken together, our data indicate a key function of IL-10 in restricting the detrimental IL-17A-signaling in stroke and further supports that IL-17A is a therapeutic opportunity for stroke treatment.

Proposed practical protocol for flow cytometry analysis of microglia from the healthy adult mouse brain: Systematic review and isolation methods’ evaluation

“…Our experimental data showed that the choice of myelin removal method affected the microglial yield far more than the enzymatic digestion step. The Percoll protocol was the most commonly used myelin removal method in the analyzed publications ( Martin et al, 2017 ; Xu et al, 2017 ; Yang et al, 2017 ; Al Mamun et al, 2018 , 2020 ; Cai et al, 2018 ; Jones et al, 2018 ; Gao et al, 2019 ; Kaiser and Feng, 2019 ; Molina Estevez et al, 2019 ; Zhou et al, 2019 ; Brioschi et al, 2020 ; Calvo et al, 2020 ; Honarpisheh et al, 2020 ; McKinsey et al, 2020 ; Pan and Wan, 2020 ; Shi et al, 2020 ; Srivastava et al, 2020 ; Manrique-Castano et al, 2021 ; Marino Lee et al, 2021 ; Piepke et al, 2021 ; Shan et al, 2021 ); our experiments confirmed that it was by far the best myelin removal method with the highest microglial yield and optimal CV. Although some studies proved usage of single Percoll gradient is efficient for myelin removal ( Jones et al, 2018 ; Kaiser and Feng, 2019 ; Molina Estevez et al, 2019 ; Brioschi et al, 2020 ; Pan and Wan, 2020 ; Manrique-Castano et al, 2021 ), most of the publications used at least 2 different concentration gradients of Percoll for more efficient myelin removal.…”

Neuroinflammation, Stroke, Blood-Brain Barrier Dysfunction, and Imaging Modalities

“…IL-10 is an anti-inflammatory cytokine that inhibits IL1-β, TNF-α, and potentially even IL-17 secretion. 43 In experimental stroke, IL-10 mRNA and protein and IL-10R mRNA increase, and transgenic mice overexpressing IL-10 show reduced infarct volumes. 44,45 Administration of IL-10 is protective in experimental stroke and limits poststroke inflammation.…”

Interleukins and Ischemic Stroke

“…IL-17A producing CD4+ αβ T cells are directly controlled via their IL-10-receptor (IL-10R), whereas IL-10 by itself has no direct effect on the IL-17A production in γδ T cells. The control of the IL-17A production in γδ T cells depended on an intact IL-10R signaling in Tregs ( 104 ).…”