2. Academic Validation
  3. Pyruvate kinase isoform M2 impairs cognition in systemic lupus erythematosus by promoting microglial synaptic pruning via the β-catenin signaling pathway

Pyruvate kinase isoform M2 impairs cognition in systemic lupus erythematosus by promoting microglial synaptic pruning via the β-catenin signaling pathway

  • J Neuroinflammation. 2021 Oct 13;18(1):229. doi: 10.1186/s12974-021-02279-9.
Li Lu  # 1 2,  Hailin Wang  # 1 2,  Xuan Liu 1 2,  Liping Tan 1 2,  Xiaoyue Qiao 1 2,  Jiali Ni 1 2,  Yang Sun 3,  Jun Liang 4,  Yayi Hou 5 6 7,  Huan Dou 8 9 10
Affiliations

Affiliations

  • 1 The State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing, 210093, People's Republic of China.
  • 2 Jiangsu Key Laboratory of Molecular Medicine, Nanjing, 210093, People's Republic of China.
  • 3 The State Key Laboratory of Pharmaceutical Biotechnology and Collaborative Innovation Center of Chemistry for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, 210023, China. yangsun@nju.edu.cn.
  • 4 Department of Rheumatology and Immunology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People's Republic of China. 13505193169@139.com.
  • 5 The State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing, 210093, People's Republic of China. yayihou@nju.edu.cn.
  • 6 Jiangsu Key Laboratory of Molecular Medicine, Nanjing, 210093, People's Republic of China. yayihou@nju.edu.cn.
  • 7 Department of Rheumatology and Immunology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People's Republic of China. yayihou@nju.edu.cn.
  • 8 The State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing, 210093, People's Republic of China. douhuan@nju.edu.cn.
  • 9 Jiangsu Key Laboratory of Molecular Medicine, Nanjing, 210093, People's Republic of China. douhuan@nju.edu.cn.
  • 10 Department of Rheumatology and Immunology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People's Republic of China. douhuan@nju.edu.cn.
  • # Contributed equally.
PMID: 34645459 DOI: 10.1186/s12974-021-02279-9
Abstract

Background: Neuropsychiatric systemic lupus erythematosus (NPSLE) is a severe complication, which involves pathological damage to the brain and cognitive function. However, its exact mechanism of action still remains unclear. In this study, we explored the role of microglia in the cognitive dysfunction of NPSLE mice. We also analyzed and compared the metabolites in the hippocampal tissues of the lupus model and control mice.

Methods: MRL/MpJ-Faslpr (MRL/lpr) female mice were used as the NPSLE mouse model. Metabolomics was used to assess hippocampal glycolysis levels. Glucose, lactic acid, IL-6, and IL-1β of the hippocampus were detected by ELISA. Based on the glycolysis pathway, we found that Pyruvate Kinase isoform M2 (PKM2) in the hippocampus was significantly increased. Thus, the expression of PKM2 was detected by qRT-PCR and Western blotting, and the localization of PKM2 in microglia (IBA-1+) or neurons (NeuN+) was assessed by immunofluorescence staining. Flow cytometry was used to detect the number and phenotype of microglia; the changes in microglial phagocytosis and the β-catenin signaling pathway were detected in BV2 cells overexpressing PKM2. For in vivo experiments, MRL/lpr mice were treated with AAV9-shPKM2. After 2 months, Morris water maze and conditional fear tests were applied to investigate the cognitive ability of mice; H&E and immunofluorescence staining were used to evaluate brain damage; flow cytometry was used to detect the phenotype and function of microglia; neuronal synapse damage was monitored by qRT-PCR, Western blotting, and immunofluorescence staining.

Results: Glycolysis was elevated in the hippocampus of MRL/lpr lupus mice, accompanied by increased glucose consumption and lactate production. Furthermore, the activation of PKM2 in hippocampal microglia was observed in lupus mice. Cell experiments showed that PKM2 facilitated microglial activation and over-activated microglial phagocytosis via the β-catenin signaling pathway. In vivo, AAV9-shPKM2-treated mice showed decreased microglial activation and reduced neuronal synapses loss by blocking the β-catenin signaling pathway. Furthermore, the cognitive impairment and brain damage of MRL/lpr mice were significantly relieved after microglial PKM2 inhibition.

Conclusion: These data indicate that microglial PKM2 have potential to become a novel therapeutic target for treating lupus encephalopathy.

Keywords

Aerobic glycolysis; LC–MS analysis; Microglia; Phagocytosis; Pyruvate kinase isoform M2; Systemic lupus erythematosus encephalopathy.

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