Icariside â ¡ attenuates bleomycin-induced pulmonary fibrosis by modulating macrophage polarization.

ETHNOPHARMACOLOGICAL RELEVANCE: Numerous studies have provided evidence supporting the significant roles of icariin, in the prevention of multiple chronic diseases like diabetes, liver fibrosis, cardiac fibrosis, renal fibrosis, and pulmonary fibrosis. In particular, Icariside II (ISE II), a prominent flavonoid glycoside derived from Epimedium brevicornum Maxim, the principal metabolite of icariin, has demonstrated noteworthy anti-inflammatory and anti-oxidant properties, along with its ability to protect against lung remodeling. However, the research exploring ISE Ⅱ's application in treating pulmonary fibrosis remains limited. AIM OF THE STUDY: The aim of this study was to assess the therapeutic efficacy of ISE II in models of pulmonary fibrosis, while also investigating its potential mechanisms of action in cell signaling pathways. MATERIALS AND METHODS: An in vitro model of pulmonary fibrosis was established by treating NIH-3T3 cells with transforming growth factor-ß1 (TGF-ß1). Western blot, RT-qPCR, and scratch test were performed to assess the effect of ISE Ⅱ. In addition, a murine model of pulmonary fibrosis was induced by intratracheal instillation of bleomycin, and the therapeutic effect of ISE Ⅱ was tested by orally administering ISE Ⅱ at a dose of 10 mg/kg. Three weeks later, lung function, micro-CT, hydroxyproline content, pathological staining, and cytokines detection of BALF or serum were used to assess the anti-fibrosis effects of ISE Ⅱ. Next, immunofluorescence staining, flow cytometry, and in vivo transcriptomics were used to investigate the underlying mechanisms of action. RESULTS: Our data revealed a significant inhibitory effect of ISE Ⅱ on the upregulation of α-smooth muscle actin (α-SMA) and collagen production induced by TGF-ß1 in fibroblasts. Meanwhile, ISE Ⅱ exerted a therapeutic effect against bleomycin-induced pulmonary fibrosis in mice by improving lung function, decreasing collagen deposition, and reducing the expression of interleukin (IL)-1ß, tumor necrosis factor α (TNF-α), TGF-ß1 and platelet-derived growth factor (PDGF) in serum and bronchoalveolar lavage fluid (BALF). Additionally, ISE Ⅱ treatment effectively attenuated the infiltration of M2 macrophages, concurrently downregulating the expression level of M2 marker genes, such as CD206, arginase-1(Arg-1), and Chitinase-Like Protein 3 (YM-1). Importantly, we observed a statistically significant reduction in the M2 phenotype of interstitial macrophages (IMs). However, the impact of ISE Ⅱ on the M2 polarization of alveolar macrophages (AMs) did not reach statistical significance. Lastly, transcriptome sequencing results suggested that the anti-pulmonary fibrosis effects of ISE Ⅱ may be mediated by the suppression of the WNT/ß-catenin signaling pathway, which modulated M2 polarization in macrophages and contributed to the amelioration of pulmonary fibrosis. By immunohistochemical analysis, it was verified that ISE Ⅱ treatment dramatically inhibited the activation of ß-catenin in fibrosis murine. CONCLUSION: Our findings indicated that ISE Ⅱ exerted anti-fibrotic effects by inhibiting pro-fibrotic macrophage polarization. The underlying mechanism of action might be mediated by modulating the WNT/ß-catenin signaling pathway to inhibit the M2 program in IMs.

Low-temperature photothermal irradiation triggers alkyl radicals burst for potentiating cancer immunotherapy.

Although low-temperature photothermal therapy (PTT) can sensitize tumors to immune checkpoint inhibition, its efficacy is still restricted in the deep and internal tumors without enough oxygen and lymphocytic infiltration. Non-oxygen-dependent alkyl radicals have been demonstrated to synergistically enhance PTT through up-regulating lipid peroxidation and reactive oxygen species (ROS). Herein, an innovative strategy based on alkyl radicals to augment immunogenetic cell death (ICD) caused by mild PTT was proposed to improve poor efficacy of immunotherapy, which composed of a photothermal material of Chinse ink, an azo-initiator of 2,2-azobis[2-(2-imidazoline-2-acyl)propane]dihydrochloride (AIPH) and a PD-L1 inhibitor of HY19991 (HY). Upon near-infrared-II laser irradiation, low-temperature (<45℃) stimulation induced a high expression of immune checkpoint receptor (PD-L1) in tumors and triggered a large amount alkyl radicals generated by AIPH. Significantly, the alkyl radicals augmented the ICD and increased the recruitment of tumor-infiltrating lymphocytes against tumors after transformation of the immunologically cold tumor microenvironment into hot by mild PTT. The released HY further enhanced the immunotherapy effect by blocking the binding of activated T lymphocytes and PD-L1. In vivo studies exhibited that the all-in-one hydrogel with synergistic mechanisms had an extraordinary ability to reverse the immunosuppressive microenvironment, stimulate innate and adaptive immune responses to eliminate tumors and prevent metastasis.