title: Maspin inhibits macrophage phagocytosis and enhances inflammatory cytokine production via activation of NF-κB signaling.
abstract: Maspin (mammary serine protease inhibitor) is a non-inhibitory member of the serine protease inhibitor superfamily and a tumor suppressor in several cancers due to its ability to inhibit cell invasion, angiogenesis, and promote apoptosis. However, its immunomodulatory function remains largely unexplored. Thus, we explored the potential link between Maspin and macrophage function, first evaluating the regulatory effects of conditioned medium (CM) of a Maspin-overexpressing CHO cell strain on mouse peritoneal macrophage phagocytosis and cytokine secretion. Next, we used a transwell co-culture system and recombinant Maspin (rMaspin) to confirm the effects of Maspin on macrophages, and attempted to clarify the underlying mechanisms. We found that irrespective of CM, rMaspin or co-culture of Maspin-overexpressing cells with macrophages impaired macrophages phagocytosing Saccharomyces cerevisiae. Furthermore, q-RT-PCR or ELISA confirmed increased IL-1β, TNF-α, IFN-γ, IL-6, IL-12, IL-10, and M1 marker iNOS production in macrophages after Maspin stimulation, but TGF-β and M2 marker Arg-1 production were suppressed. Western blot showed activated NF-κB signaling in Maspin-stimulated macrophages; upregulated cytokines were lowered, and impaired phagocytosis recovered after blocking NF-κB signaling with PDTC. Thus, Maspin mildly inhibited phagocytic activity, but markedly enhanced inflammatory cytokine production and likely skewed macrophages towards M1 polarization, partially due to activation of NF-κB signaling. These results reveal a novel biological function of Maspin in modulating macrophage activity and may open a new avenue for Maspin-based tumor therapy.
authors.affiliation: National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun 130024, China; Research Center of Agriculture and Medicine Gene Engineering of Ministry of Education, Northeast Normal University, Changchun 130024, China.
authors.forename: Yimeng
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Research Center of Agriculture and Medicine Gene Engineering of Ministry of Education, Northeast Normal University, Changchun 130024, China.
authors.forename: Luguo
authors.initials: L
authors.lastname: Sun
authors.affiliation: National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun 130024, China; Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China.
authors.forename: Zhenbo
authors.initials: Z
authors.lastname: Song
authors.affiliation: National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun 130024, China; Research Center of Agriculture and Medicine Gene Engineering of Ministry of Education, Northeast Normal University, Changchun 130024, China.
authors.forename: Danfeng
authors.initials: D
authors.lastname: Wang
authors.affiliation: National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun 130024, China. Electronic address: baoyl800@nenu.edu.cn.
authors.forename: Yongli
authors.initials: Y
authors.lastname: Bao
authors.affiliation: Research Center of Agriculture and Medicine Gene Engineering of Ministry of Education, Northeast Normal University, Changchun 130024, China; Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China. Electronic address: liyx486@nenu.edu.cn.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D016466:CHO Cells; D018920:Coculture Techniques; D003412:Cricetulus; D016207:Cytokines / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007249:Inflammation / Q000276:immunology / Q000378:metabolism; D008262:Macrophage Activation / Q000276:immunology*; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism; D010587:Phagocytosis / Q000276:immunology; D016133:Polymerase Chain Reaction; D015843:Serpins / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology*; D014162:Transfection
chemical_list: D016207:Cytokines; D016328:NF-kappa B; C085344:SERPIN-B5; D015843:Serpins
keywords: Cytokine production; Macrophage; Phagocytosis; Polarization; Tumor microenvironment; Tumor suppressor