Macrophages are the most abundant alternative immune cells in the tumor microenvironment (TME). The cross-talk between macrophages and tumor cells provides an important shelter for the occurrence and development of tumors. As an important information transfer medium, exosomes play an important role in intercellular communication. Nonetheless, how exosomal lncRNAs coordinate the communication between tumor cells and immune cells in hepatocellular carcinoma (HCC) is incompletely understood. We found that HCC exosomes-derived antisense RNA of SLC16A1(SLC16A1-AS1) promoted the malignant progression of HCC by regulating macrophage M2-type polarization. Mechanistically, the HCC exosomal SLC16A1-AS1 enhanced mRNA stabilization of SLC16A1 in macrophage by promoting the interaction between 3\' untranslated regions (3\'UTR) of SLC16A1 mRNA and heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1). As a lactate transporter, SLC16A1 accelerated lactate influx and then activated c-Raf/ERK signaling to induce M2 polarization of macrophages. Reciprocally, M2 macrophages secreted IL-6 to activate STAT3 and then induce METTL3 transcription in HCC cells, which increasing m6A methylation and stabilization of SLC16A1-AS1. In turn, the reciprocal SLC16A1-AS1/IL-6 signaling between HCC cells and M2 macrophages promoted the proliferation, invasion and glycolysis of HCC cells. Our study highlights that exosomal SLC16A1-AS1 acts as a signaling message that induces lactate-mediated M2 polarization of macrophages, and implies that SLC16A1-AS1 might be an applicable target for therapeutic treatment of HCC.

In this issue of World Journal of Gastroenterology, Huang et al reported that Calculus bovis (CB), a traditional Chinese herbal medicine, impedes the growth of liver cancers in vivo. Through further in vitro studies, they showed that CB suppressed the M2 polarization of tumor-associated macrophages by suppressing the Wnt signaling pathway, which consequently inhibited the growth of liver cancer. Although the effects of traditional Chinese herbal medicine are often not scientifically proven, Huang et al successfully identified the molecular mechanism involved in the anticancer effect of CB, and it is anticipated that the molecular mechanisms involved in the effects of other traditional Chinese herbal medicines will be scientifically elucidated, as demonstrated in this article.

Long non-coding RNA (lncRNA) LINC00958 has been reported to promote many gynecological cancers, but its detailed function in OC remains unclear. Cancer stem cells (CSCs) and tumor-associated macrophages (TAMs) have been reported to participate in the occurrence and metastasis of cancers. We want to explore the effects of exosomal LINC00958 on cell stemness and macrophage polarization in OC. LINC00958 expression was first verified in OC cells and its function on cell stemness was verified by subcellular fractionation analysis, sphere formation assay and so on. Exosomal LINC00958 was secreted from OC cells and the model of M2 macrophage polarization was established to further verify the impact of exosomal LINC00958 on the cell stemness and macrophage polarization of OC cells using several mechanism experiments including flow cytometry, RNA pulldown, luciferase reporter assays and so on. LINC00958 was up-regulated in OC cells and exosomal LINC00958 enhanced the stem cell-like properties of OC cells and M2 macrophage polarization. Furthermore, LINC00958 combined with glioma-associated oncogene homolog 1 (GLI1) to activate Hedgehog pathway, thereby promoting M2 polarization. Exosomal LINC00958 maintained OC cell stemness and induced M2 polarization via the Hedgehog signaling pathway.

Reperfusion strategies, the standard therapy for acute myocardial infarction (AMI), may result in ischemia/reperfusion (I/R) damage. Suppressor of cytokine signaling1 (SOCS1) exerts a cardioprotective function in myocardial I/R damage. Here, we investigated epigenetic modulators that deregulate SOCS1 in cardiomyocytes under hypoxia/reoxygenation (H/R) conditions. Human AC16 cardiomyocytes were exposed to H/R conditions to generate a cell model of myocardial I/R damage. Expression of mRNA and protein was detected by quantitative PCR and western blot analysis, respectively. Cell migratory and invasive abilities were evaluated by transwell assay. Cell apoptosis and M2 macrophage polarization were assessed by flow cytometry. TNF-α, IL-1β, and IL-6 levels were examined by ELISA. The interaction of KLF4 with SOCS1 was verified by chromatin immunoprecipitation and luciferase assays. SOCS1 and transcription factor KLF4 protein levels were underexpressed by 75% and 57%, respectively, in H/R-exposed AC16 cardiomyocytes versus control cells. Under H/R conditions, forced SOCS1 expression (2.7 times) induced cell migration (2.2 times) and invasion (1.9 times) and hindered cell apoptosis (by 45%) of AC16 cardiomyocytes as well as enhanced M2 macrophage polarization (4.6 times). Mechanistically, KLF4 upregulation promoted SOCS1 transcription (2.6 times) and expression (2.6 times) by binding to the SOCS1 promoter. Decrease of SOCS1 (by 51%) reversed the effects of KLF4 upregulation on cardiomyocyte migration, invasion and apoptosis, and M2 macrophage polarization under H/R conditions. Additionally, SOCS1 and KLF4 were underexpressed by 56% and 63%, respectively, in AMI serum. Our study indicates that KLF4-induced upregulation of SOCS1 can attenuate H/R-triggered apoptosis of AC16 cardiomyocytes and enhance M2 macrophage polarization.

Aim: To determine the mechanism of Calcitonin gene-related peptide (CGRP) in bone healing.Materials & methods: Alkaline phosphatase (ALP) activity and inflammatory-factor levels were detected using ELISA. Osteogenic differentiation was assessed using Alizarin red staining technique. The interaction between histone deacetylase 6 (HDAC6) and A-kinase anchoring protein 12 (AKAP12) was investigated through Co- immunoprecipitation.Results: CGRP treatment promoted rat bone marrow-derived macrophages (BMDMs) M2 polarization. CGRP facilitated osteogenic differentiation by enhancing M2 polarization of BMDMs. Mechanistically, CGRP promoted AKAP12 acetylation to activate the extracellular regulated protein kinases pathway by HDAC6 inhibition.Conclusion: CGRP promoted M2 polarization of rat BMDMs and facilitated osteogenic differentiation through the HDAC6/AKAP12/extracellular regulated protein kinases signaling pathway, thereby promoting bone healing.
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Plant-derived exosomes (PEs) possess an array of therapeutic properties, including antitumor, antiviral, and anti-inflammatory capabilities. They are also implicated in defensive responses to pathogenic attacks. Spinal cord injuries (SCIs) regeneration represents a global medical challenge, with appropriate research concentration on three pivotal domains: neural regeneration promotion, inflammation inhibition, and innovation and application of regenerative scaffolds. Unfortunately, the utilization of PE in SCI therapy remains unexplored. Herein, we isolated PE from the traditional Chinese medicinal herb, Lycium barbarum L. and discovered their inflammatory inhibition and neuronal differentiation promotion capabilities. Compared with exosomes derived from ectomesenchymal stem cells (EMSCs), PE demonstrated a substantial enhancement in neural differentiation. We encapsulated isoliquiritigenin (ISL)-loaded plant-derived exosomes (ISL@PE) from L. barbarum L. within a 3D-printed bionic scaffold. The intricate construct modulated the inflammatory response following SCI, facilitating the restoration of damaged axons and culminating in ameliorated neurological function. This pioneering investigation proposes a novel potential route for insoluble drug delivery via plant exosomes, as well as SCI repair. The institutional animal care and use committee number is UJS-IACUC-2020121602.

Renal cell carcinoma (RCC) is one of the most common malignant tumors of the kidney, presenting significant challenges for clinical diagnosis and treatment. Macrophages play crucial roles in RCC, promoting tumor progression and warranting further investigation. Previous studies have identified LHFPL2 as a transmembrane protein associated with reproduction, but its relationship with tumors or macrophages has not been discussed. This study utilized transcriptomic sequencing data from 609 KIRC patients in the TCGA database and single-cell sequencing data from 34,326 renal carcinoma cells for subsequent analysis. We comprehensively evaluated the expression of LHFPL2 and its relationship with clinical features, tumor prognosis, immune infiltration, and mutations. Additionally, we further assessed the correlation between LHFPL2 and macrophage M2 polarization using single-cell data and explored its potential as a cancer therapeutic target through molecular docking. The results demonstrated that LHFPL2 is upregulated in RCC and associated with poor survival rates. In clinical staging, the proportion of malignant and high-metastasis patients was higher in the high-LHFPL2 group than in the low-LHFPL2 group. Furthermore, we found that LHFPL2 influences RCC immune infiltration, with its expression positively correlated with various immune checkpoint and M2-related gene expressions, positively associated with M2 macrophage infiltration, and negatively correlated with activated NK cells. Moreover, LHFPL2 showed specific expression in macrophages, with the high-expression subgroup exhibiting higher M2 polarization, hypoxia, immune evasion, and angiogenesis scores, promoting tumor progression. Finally, we predicted several potential drugs targeting LHFPL2, such as conivaptan and nilotinib. Our analysis elaborately delineates the immune characteristics of LHFPL2 in the tumor microenvironment and its positive correlation with macrophage M2 polarization, providing new insights into tumor immunotherapy. We also propose potential FDA-approved drugs targeting this gene, which should be tested for their binding effects with LHFPL2 in future studies.

Stable infiltration of myeloid cells, especially tumor-associated M2 macrophages, acts as one of the essential features of the tumor immune microenvironment by promoting the malignant progression of hepatocellular carcinoma (HCC). However, the factors affecting the infiltration of M2 macrophages are not fully understood. In this study, we found the molecular subtypes of HCC with the worst prognosis are characterized by immune disorders dominated by myeloid cell infiltration. Myeloid cell nuclear differentiation antigen (MNDA) was significantly elevated in the most aggressive subtype and exhibited a positively correlation with M2 infiltration and HCC metastasis. Moreover, MNDA functioned as an independent prognostic predictor and has a good synergistic effect with some existing prognostic clinical indicators. We further confirmed that MNDA was primarily expressed in tumor M2 macrophages and contributed to the enhancement of its polarization by upregulating the expression of the M2 polarization enhancers. Furthermore, MNDA could drive the secretion of M2 macrophage-derived pro-metastasis proteins to accelerate HCC cells metastasis both in vivo and in vitro. In summary, MNDA exerts a protumor role by promoting M2 macrophages polarization and HCC metastasis, and can serve as a potential biomarker and therapeutic target for HCC.

BACKGROUND: Azithromycin (AZM) has been proposed as a potential therapeutic drug in acute pulmonary injury due to its immunomodulatory and anti-inflammatory properties. However, its therapeutic mechanism remains not fully understood.
METHODS: LPS was used to stimulate MLE-12 cells and RAW264.7 macrophages. Analyses of viability and apoptosis were performed by CCK-8 assay and flow cytometry, respectively. Protein analysis was performed by immunoblotting, and mRNA expression was tested by quantitative PCR. The secretion levels of TNF-α and IL-6 were detected by ELISA. MDA, GSH, ROS and Fe2+ contents were analyzed using assay kits.
RESULTS: Administration of AZM or depletion of methyltransferase-like 3 (Mettl3) could attenuate LPS-triggered apoptosis, inflammation and ferroptosis in MLE-12 alveolar cells, as well as enhance M2 polarization of LPS-stimulated RAW264.7 macrophages. In LPS-exposed MLE-12 and RAW264.7 cells, AZM reduced Mettl3 protein expression and inactivated the NF-κB signaling through downregulation of Mettl3. Furthermore, Mettl3 restoration abated AZM-mediated anti-apoptosis, anti-inflammation and anti-ferroptosis effects in LPS-exposed MLE-12 cells and reversed AZM-mediated M2 polarization enhancement of LPS-exposed RAW264.7 macrophages.
CONCLUSIONS: Our study indicates that AZM can promote M2 polarization of LPS-exposed RAW264.7 macrophages and attenuate LPS-triggered injury of MLE-12 alveolar cells by inactivating the Mettl3-mediated NF-κB pathway.

UNASSIGNED: The morbidity and mortality of sepsis are increasing year by year. Statistically, 40-50% of patients with sepsis have concomitant myocardial injury, and its mortality rate is higher than that of patients with sepsis only. Therefore, it is of great significance to elucidate the mechanism of sepsis-induced myocardial injury.
UNASSIGNED: Human monocytes (THP-1) were used to induce M0 macrophages, followed by treated with lipopolysaccharide (LPS). Cardiomyocytes (AC16) were co-cultured with the conditioned medium of LPS-induced macrophages to induce injury. Quantitative real-time PCR was employed to detect the mRNA levels of peroxisome proliferator-activated receptor α (PPARA) and dual specificity phosphatase 1 (DUSP1). Protein levels of PPARA, macrophage polarization-related markers, apoptosis-related markers, mitochondria-related proteins, and DUSP1 were analyzed by Western blot. Flow cytometry was used to assess M1/M2 cell rates and apoptosis. Low PPARA expression could serve as a biomarker for patients with sepsis. PPARA overexpression enhanced M2 polarization and suppressed M1 polarization in LPS-induced macrophages, and it could alleviate cardiomyocyte injury in co-cultured system. PPARA bound to the DUSP1 promoter region and facilitated its expression. DUSP1 knockdown reversed the effect of PPARA overexpression on M2 polarization and cardiomyocyte injury.
UNASSIGNED: PPARA attenuated cardiomyocyte injury by promoting macrophage M2 polarization through increasing DUSP1 expression, suggesting that PPARA might be a therapy target for sepsis-induced myocardial injury.