2. Academic Validation
  3. Macrophage-derived SPP1 exacerbate myocardial injury by interacting with fibroblasts in viral myocarditis

Macrophage-derived SPP1 exacerbate myocardial injury by interacting with fibroblasts in viral myocarditis

  • Biol Direct. 2025 Mar 14;20(1):30. doi: 10.1186/s13062-025-00621-2.
Xiuyun Duan # 1,  Li Zhang # 2 3 4,  Keyu Liu 1 4,  Kaiyin Guo 5,  Yingnan You 2 3 4,  Hailin Jia 2 3 4,  Shan Zhou 2 3 4,  Bo Han 6 7 8 9 10
Affiliations

Affiliations

  • 1 Department of Pediatric Cardiology, Cheeloo Colledge of Medicine, Shandong Provincial Hospital, Shandong University, Jinan, Shandong, China.
  • 2 Department of Pediatric Cardiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China.
  • 3 Shandong Provincial Clinical Research Center for Children's Health and Disease office, Shandong Provincial Hospital, Jinan, Shandong, China.
  • 4 Medical Science and Technology Innovation Center, Shandong First Medical University, Shandong Academy of Medical Sciences, Jinan, Shandong, China.
  • 5 Rui Jin Hospital Nanxiang Branch, Shanghai, 201802, China.
  • 6 Department of Pediatric Cardiology, Cheeloo Colledge of Medicine, Shandong Provincial Hospital, Shandong University, Jinan, Shandong, China. hanbo35@163.com.
  • 7 Department of Pediatric Cardiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China. hanbo35@163.com.
  • 8 Shandong Provincial Clinical Research Center for Children's Health and Disease office, Shandong Provincial Hospital, Jinan, Shandong, China. hanbo35@163.com.
  • 9 Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong, China. hanbo35@163.com.
  • 10 Medical Science and Technology Innovation Center, Shandong First Medical University, Shandong Academy of Medical Sciences, Jinan, Shandong, China. hanbo35@163.com.
  • # Contributed equally.
PMID: 40087693 DOI: 10.1186/s13062-025-00621-2
Abstract

Background: Viral myocarditis (VMC) is an inflammatory myocardial condition triggered by viral infections which involves pathogenic-related damage and immune-mediated damage. However, the precise immunopathogenic mechanisms underlying VMC remain elusive.

Methods: We performed single-cell RNA Sequencing on mouse hearts during the acute phase of CVB3-induced VMC. After manually annotating cell types, functional analyses of macrophage were performed by cell ratio changes, customized gene set module scoring and CellPhoneDB. Utilizing indirect co-culture experiments in vitro, the effects of macrophage-derived SPP1 on cardiac fibroblasts were investigated. Depletion of macrophages and inhibition of SPP1 expression in mice were carried out to study the effects of macrophage-derived SPP1 on cardiac function, inflammation levels, and myocardial injury in mice with VMC.

Results: Our data revealed that macrophages are the major immune cells which infiltrate the heart during the acute phase of VMC, particularly a macrophage subpopulation which highly expresses Spp1 (Spp1+ macrophages) and exhibited characteristics of peripheral blood monocytes. Spp1+ macrophages communicate extensively with fibroblasts during VMC, and that SPP1 promotes fibroblast conversion to an inflammatory phenotype with high Ccl2/Ccl7 expression. This in turn increases monocyte chemotaxis to the heart. Besides, a partial depletion of macrophages in the early stages of VMC attenuated myocardial inflammation and myocardial injury in mice. Inhibition of SPP1 reduced cardiac macrophage infiltration, attenuated myocardial inflammation, and improved cardiac function in VMC mice.

Conclusion: Our findings suggested that Spp1+ macrophages could self-recruit, and macrophage-derived SPP1 exacerbated myocardial immune injury by promoting high Ccl2/Ccl7 expression in fibroblasts. Our study advances understandings of VMC pathogenesis, and provides novel insight into potential immunotherapies for VMC.

Keywords

Fibroblasts; Macrophages; SPP1; Single-cell analysis; Viral myocarditis.

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