Galectin-3 mediates lysosome-related inflammation within monocyte-derived macrophages in a mouse model of ischemic brain injury
Miao Wang, Zhentai Huang, Zhihong Du, Jiajing Shan, Qing Ye, Lingxiao Lu, Ming Jiang, Fei Xu, Ziyang Liu, David J.R. Fulton, Rehana K. Leak, Babak Razani, Jun Chen, Xiaoming Hu
Miao Wang, Zhentai Huang, Zhihong Du, Jiajing Shan, Qing Ye, Lingxiao Lu, Ming Jiang, Fei Xu, Ziyang Liu, David J.R. Fulton, Rehana K. Leak, Babak Razani, Jun Chen, Xiaoming Hu
View: Text | PDF
Research Article Inflammation Neuroscience

Galectin-3 mediates lysosome-related inflammation within monocyte-derived macrophages in a mouse model of ischemic brain injury

Abstract

Circulating monocyte-derived macrophages (MDMø) rapidly invade the brain after stroke, exerting both detrimental and beneficial effects. Elucidating mechanisms that mediate detrimental properties of MDMø may identify therapeutic strategies to divert MDMø from destructive phenotypes, while preserving their favorable effects. Toward this goal, the current study explores the function of Galectin-3 (GAL3) in MDMø and elucidates mechanisms whereby MDMø-derived GAL3 exacerbates stroke injury. In the acutely injured brain, GAL3 expression was upregulated primarily within MDMø. Global KO of GAL3 reduced brain infarcts in the short term but did not sustain long-term positive outcomes. Using BM chimera mice, macrophage transplantation, and myeloid cell–specific GAL3-KO (LysMCre+/–Lgals3fl/fl) mice, we demonstrated that GAL3 in MDMø mediated acute infarct expansion after stroke. Coculturing brain lysate–treated, BM-derived macrophages (BMDMs) with oxygen glucose deprivation–challenged neurons induced neurotoxicity that was mitigated by the cell-permeable, selective GAL3 inhibitor TD139. GAL3 triggered cathepsin induction and lysosomal leakage in BMDMs, leading to inflammasome activation. Systemic and transient TD139 treatment in the acute injury phase reduced infarcts, tempered neuroinflammation, and improved long-term neurological outcomes. Therefore, MDMø-derived GAL3 represents a drug target that could be accessed in peripheral blood to potentially mitigate post-stroke brain injury.

Authors

Miao Wang, Zhentai Huang, Zhihong Du, Jiajing Shan, Qing Ye, Lingxiao Lu, Ming Jiang, Fei Xu, Ziyang Liu, David J.R. Fulton, Rehana K. Leak, Babak Razani, Jun Chen, Xiaoming Hu

×

Figure 7

GAL3-mediated cathepsin induction enhances NLRP3 expression in MDMø and amplifies post-stroke inflammation in the CNS.

Options: View larger image (or click on image) Download as PowerPoint
GAL3-mediated cathepsin induction enhances NLRP3 expression in MDMø and ...
(A) Immunostaining of NLRP3 and GAL3 in cultured BMDMs under specified conditions for 6 h. Scale bar: 10 μm. (B) Quantification of NLRP3 intensity and number of NLRP3+ puncta per 100 μm2 cell area within BMDMs in indicated groups. N = 15 randomly selected BMDMs from 3 independent experiments. (C) Immunoblot of cleaved caspase-1 and active IL-1β in culture media of BMDMs under specified conditions for 6 h. β-ACTIN from corresponding cells was used as control. (D) Quantification of cleaved caspase-1 and IL-1β in indicated groups. N = 3/condition. (E) BMDMs in cell culture inserts were treated with brain lysates and MCC950 (10 μM) or vehicle controls for 6 h. The treated BMDMs were then cocultured with OGD neurons for 18 h. Representative images show MAP2 immunostaining under indicated conditions. Coverage areas of MAP2-stained neurons were quantified. N = 6 samples per condition. Scale bar: 40 μm. (F) Immunostaining of NLRP3, CD68, and IBA1 3 d after tMCAO in WT mice treated with vehicle or TD139. NLRP3 intensity within CD68+ cells was quantified. N = 6/condition. Scale bar: 20 μm. (G) RNA levels of Il-1b and Il-6 expression in ipsilateral brain lysates collected 5 d after tMCAO. N = 3–5/group. *P < 0.05, **P < 0.01, ***P < 0.001. Two-tailed, unpaired Student’s t test (F) or 1-way ANOVA and Bonferroni’s test (B, D, E, and G).