Features of the Population of Mouse Peritoneal Macrophages Isolated after Stimulation with Concanavalin A and Thioglycolate

MAFB in Macrophages Regulates Prostaglandin E2-Mediated Lipid Mediator Class Switch through ALOX15 in Ischemic Acute Kidney Injury

Monocytes and macrophages express the transcription factor MAFB (V-maf musculoaponeurotic fibrosarcoma oncogene homolog B) and protect against ischemic acute kidney injury (AKI). However, the mechanism through which MAFB alleviates AKI in macrophages remains unclear. In this study, we induced AKI in macrophage lineage-specific Mafb-deficient mice (C57BL/6J) using the ischemia-reperfusion injury model to analyze these mechanisms. Our results showed that MAFB regulates the expression of Alox15 (arachidonate 15-lipoxygenase) in macrophages during ischemic AKI. The expression of ALOX15 was significantly decreased at the mRNA and protein levels in macrophages that infiltrated the kidneys of macrophage-specific Mafb-deficient mice at 24 h after ischemia-reperfusion injury. ALOX15 promotes the resolution of inflammation under acute conditions by producing specialized proresolving mediators by oxidizing essential fatty acids. Therefore, MAFB in macrophages promotes the resolution of inflammation in ischemic AKI by regulating the expression of Alox15. Moreover, MAFB expression in macrophages is upregulated via the COX-2/PGE2/EP4 pathway in ischemic AKI. Our in vitro assay showed that MAFB regulates the expression of Alox15 under the COX-2/PGE2/EP4 pathway in macrophages. PGE2 mediates the lipid mediator (LM) class switch from inflammatory LMs to specialized proresolving mediators. Therefore, MAFB plays a key role in the PGE2-mediated LM class switch by regulating the expression of Alox15. Our study identified a previously unknown mechanism by which MAFB in macrophages alleviates ischemic AKI and provides new insights into regulating the LM class switch in acute inflammatory conditions.

P-Hydroxylcinnamaldehyde induces tumor-associated macrophage polarization toward the M1 type by regulating the proteome and inhibits ESCC in vivo and in vitro

P-Hydroxylcinnamaldehyde (CMSP) was firstly isolated from Chinese medicine Cochinchinnamomordica seed (CMS) by our team and has been verified to have growth-inhibiting abilities in malignant tumors including esophageal squamous cell carcinoma (ESCC). However, the detailed mechanism of its function is still unclear. Tumor-associated macrophages (TAMs) are an essential component of the tumor microenvironment (TME), playing important roles in tumor growth, metastasis, angiogenesis, and epithelial-mesenchymal transition (EMT). In the present study, we found that the percentage of M1-like macrophages was significantly increased in TME of ESCC cell derivedxenograft tumor model after CMSP treatment, while the ratios of other immune cells showed relatively low variation. To confirm these results, we further examined the effect of CMSP on macrophage polarization in vitro. The results revealed that CMSP also could induce phorbol-12-myristate-13-acetate (PMA)-induced M0 macrophages from THP-1 and mouse peritoneal macrophages toward the M1-like macrophages. Furthermore, CMSP could exert anti-tumor effect through TAMs in vitro co-culture model, in addition, the growth inhibition effect of CMSP was partly abolished in macrophage depletion model. To determine the potential pathway of CMSP induced polarization, we used quantitative proteomics (label-free) technology to explore the proteomic changes under CMSP treatment. The results revealed that immune-activating protein and M1 macrophage biomarkers were significantly increased after CMSP treatment. More importantly, CMSP stimulated pathways related to M1 macrophage polarization, such as the NF-κB signaling pathway and Toll-like receptor pathway, indicating that CMSP might induce M1-type macrophage polarization through these pathways. In conclusion, CMSP can regulate immune microenvironment in vivo and induce TAM polarization toward the M1 type by promoting proteomic changes, and exert anti-tumor effect through TAMs.

Human MIKO-1, a Hybrid Protein That Regulates Macrophage Function, Suppresses Lung Fibrosis in a Mouse Model of Bleomycin-Induced Interstitial Lung Disease

Although interstitial lung disease (ILD) is a life-threatening pathological condition that causes respiratory failure, the efficiency of current therapies is limited. This study aimed to investigate the effects of human MIKO-1 (hMIKO-1), a hybrid protein that suppresses the abnormal activation of macrophages, on murine macrophage function and its therapeutic effect in a mouse model of bleomycin-induced ILD (BLM-ILD). To this end, the phenotype of thioglycolate-induced murine peritoneal macrophages co-cultured with hMIKO-1 was examined. The mice were assigned to normal, BLM-alone, or BLM + hMIKO-1 groups, and hMIKO-1 (0.1 mg/mouse) was administered intraperitoneally from day 0 to 14. The mice were sacrificed on day 28, and their lungs were evaluated by histological examination, collagen content, and gene expression levels. hMIKO-1 suppressed the polarization of murine macrophages to M2 predominance in vitro. The fibrosis score of lung pathology and lung collagen content of the BLM + hMIKO-1 group were significantly lower than those in the BLM-alone group. The expression levels of TNF-α, IL-6, IL-1β, F4/80, and TIMP-1 in the lungs of the BLM + hMIKO-1 group were significantly lower than those in the BLM-alone group. These findings indicate that hMIKO-1 reduces lung fibrosis and may be a future therapeutic candidate for ILD treatment.