Effects of TRIM59 on RAW264.7 macrophage gene expression and function

Myeloid Cell Trim59 Deficiency Worsens Experimental Ischemic Stroke and Alters Cerebral Proteomic Profile

Background

Tripartite motif containing 59 (TRIM59) is a ubiquitin ligase and is involved in the pathogenesis of various diseases, including cancers, sepsis, and other immune-related diseases. However, it has not been defined whether TRIM59 plays a role in ischemic stroke in mice.

Methods

This study determined the influence of Trim59 deficiency on experimental stroke outcomes and the cerebral proteomic profile using myeloid cell Trim59 conditional knockout (Trim59-cKO) mice and a label-free quantitative proteomic profiling technique. The possible mechanisms by which TRIM59 affected stroke onset were elucidated by in vivo and in vitro experiments.

Results

Immunofluorescence staining results showed that TRIM59 expression was up-regulated after cerebral ischemia and co-localized with macrophages. Myeloid cell Trim59 deficiency exacerbated ischemic injury on day 3 after experimental stroke. In proteomic analysis, 23 differentially expressed proteins were identified in ischemic brain of Trim59-cKO mice as compared to Trim59flox/flox mice. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that the differentially expressed proteins were enriched in complement and coagulation cascades. Protein-protein interaction analysis suggested the central role of clusterin in the interaction network. ELISA and Western blot assays confirmed the reduced levels of clusterin protein in the ischemic brains of Trim59-cKO mice. Further experimental results showed that clusterin was expressed in neurons. Conditional co-culture experiments of primary neurons and bone marrow-derived macrophages demonstrated that LPS stimulated macrophages to secrete complement C3. In addition, TRIM59 may affect the changes in clusterin expression in an indirect manner by influencing the secretion of complement C3 in macrophages. In vivo experiments also proved a significant increase in C3 levels in the brains of Trim59-cKO mice after ischemia.

Conclusion

Myeloid cell Trim59 deficiency aggravated ischemic stroke outcomes in conjunction with a distinct cerebral proteomic profile, and the underlying mechanism may be related to the regulation of macrophage C3 expression by TRIM59.

Phenotypic comparison and the potential antitumor function of immortalized bone marrow-derived macrophages (iBMDMs)

Introduction

Macrophages are an important component of innate immunity and involved in the immune regulation of multiple diseases. The functional diversity and plasticity make macrophages to exhibit different polarization phenotypes after different stimuli. During tumor progression, the M2-like polarized tumor-associated macrophages (TAMs) promote tumor progression by assisting immune escape, facilitating tumor cell metastasis, and switching tumor angiogenesis. Our previous studies demonstrated that functional remodeling of TAMs through engineered-modifying or gene-editing provides the potential immunotherapy for tumor. However, lack of proliferation capacity and maintained immune memory of infused macrophages restricts the application of macrophage-based therapeutic strategies in the repressive tumor immune microenvironment (TIME). Although J2 retrovirus infection enabled immortalization of bone marrow-derived macrophages (iBMDMs) and facilitated the mechanisms exploration and application, little is known about the phenotypic and functional differences among multi kinds of macrophages.

Methods

HE staining was used to detect the biosafety of iBMDMs, and real-time quantitative PCR, immunofluorescence staining, and ELISA were used to detect the polarization response and expression of chemokines in iBMDMs. Flow cytometry, scratch assay, real-time quantitative PCR, and crystal violet staining were used to analyze its phagocytic function, as well as its impact on tumor cell migration, proliferation, and apoptosis. Not only that, the inhibitory effect of iBMDMs on tumor growth was detected through subcutaneous tumor loading, while the tumor tissue was paraffin sectioned and flow cytometry was used to detect its impact on the tumor microenvironment.

Results

In this study, we demonstrated iBMDMs exhibited the features of rapid proliferation and long-term survival. We also compared iBMDMs with RAW264.7 cell line and mouse primary BMDMs with in vitro and in vivo experiments, indicating that the iBMDMs could undergo the same polarization response as normal macrophages with no obvious cellular morphology changes after polarization. What's more, iBMDMs owned stronger phagocytosis and pro-apoptosis functions on tumor cells. In addition, M1-polarized iBMDMs could maintain the anti-tumor phenotypes and domesticated the recruited macrophages of receptor mice, which further improved the TIME and repressed tumor growth.

Discussion

iBMDMs can serve as a good object for the function and mechanism study of macrophages and the optional source of macrophage immunotherapy.

TRIM21 aggravates cardiac injury after myocardial infarction by promoting M1 macrophage polarization

Macrophage polarization followed by myocardial infarction (MI) is essential for wound healing. Tripartite motif-containing protein 21 (TRIM21), a member of E3 ubiquitin ligases, is emerging as a mediator in cardiac injury and heart failure. However, its function in modulating post-MI macrophage polarization remains elusive. Here, we detected that the levels of TRIM21 significantly increased in macrophages of wild-type (WT) mice after MI. In contrast, MI was ameliorated in TRIM21 knockout (TRIM21-/-) mice with improved cardiac remodeling, characterized by a marked decrease in mortality, decreased infarct size, and improved cardiac function compared with WT-MI mice. Notably, TRIM21 deficiency impeded the post-MI apoptosis and DNA damage in the hearts of mice. Consistently, the accumulation of M1 phenotype macrophages in the infarcted tissues was significantly reduced with TRIM21 deletion. Mechanistically, the deletion of TRIM21 orchestrated the process of M1 macrophage polarization at least partly via a PI3K/Akt signaling pathway. Overall, we identify TRIM21 drives the inflammatory response and cardiac remodeling by stimulating M1 macrophage polarization through a PI3K/Akt signaling pathway post-MI.