Isoandrographolide inhibits NLRP3 inflammasome activation and attenuates silicosis in mice

Chinese medicine as a therapeutic option for pulmonary fibrosis: Clinical efficacies and underlying mechanisms

ETHNIC PHARMACOLOGICAL RELEVANCE

Pulmonary fibrosis (PF) is a fibrotic interstitial lung disease caused by continuous damage and excessive repair of alveolar epithelial cells, the pathogenesis of which is not fully understood. At present, the incidence of PF has increased significantly around the world. The therapeutic arsenals against PF are relatively limited, with often poor efficacy and many adverse effects. As a conventional and effective therapeutic strategy, traditional Chinese medicine (TCM) has been widely applied in treating lung fibrosis for thousands of years in China. Due to the multi-ingredient, multi-target characteristics, Chinese medicines possess promising clinical benefits for PF treatment.

AIM OF THIS REVIEW

This review aims to systematically analyze the clinical efficacy of Chinese medicine on PF, and further summarize the relevant mechanisms of Chinese medicine treating PF in preclinical studies, in order to provide a comprehensive insight into the beneficial effects of Chinese medicines on PF.

METHODS

Eight major Chinese and English databases were searched from database inception up to October 2022, and all randomized clinical trials (RCTs) investigating the effects of Chinese medicine intervention on effectiveness and safety in the treatment of PF patients were included. Subsequently, preclinical studies related to the treatment of PF in Chinese medicine, including Chinese medicine compounds, Chinese herbal materials and extracts, and Chinese herbal formulas (CHFs) were searched through PubMed and Web of science to summarize the related mechanisms of Chinese medicine against PF.

RESULTS

A total of 56 studies with 4019 patients were included by searching the relevant databases. Total clinical efficacy, pulmonary function, blood gas analysis, lung high resolution CT (HRCT), 6 min walk test (6-MWT), St George's Respiratory Questionnaire (SGRQ) scores, clinical symptom scores, TCM syndrome scores and other outcome indicators related to PF were analyzed. Besides, numerous preclinical studies have shown that many Chinese medicine compounds, Chinese herbal materials and extracts, and CHFs play a preventive and therapeutic role in PF by reducing oxidative stress, ameliorating inflammation, inhibiting epithelial-mesenchymal transition and myofibroblasts activation, and regulating autophagy and apoptosis.

CONCLUSION

Chinese medicines show potential as supplements or substitutes for treating PF. And studies on Chinese medicines will provide a new approach to better management of PF.

Anti-inflammatory protein TSG-6 secreted by BMSCs attenuates silica-induced acute pulmonary inflammation by inhibiting NLRP3 inflammasome signaling in macrophages

Silicosis is a severe occupational lung disease caused by inhalation of silica particles. Unfortunately, there are currently limited treatment options available for silicosis. Recent advances have indicated that bone marrow mesenchymal stem cells (BMSCs) have a therapeutic effect on silicosis, but their efficacy and underlying mechanisms remain largely unknown. In this study, we focused on the early phase of silica-induced lung injury to investigate the therapeutic effect of BMSCs. Our findings demonstrated that BMSCs attenuated silica-induced acute pulmonary inflammation by inhibiting NLRP3 inflammasome pathways in lung macrophages. To further understand the mechanisms involved, we utilized RNA sequencing to analyze the transcriptomes of BMSCs co-cultured with silica-stimulated bone marrow-derived macrophages (BMDMs). The results clued tumor necrosis factor-stimulated gene 6 (TSG-6) might be a potentially key paracrine secretion factor released from BMSCs, which exerts a protective effect. Furthermore, the anti-inflammatory and inflammasome pathway inhibition effects of BMSCs were attenuated when TSG-6 expression was silenced, both in vivo and in vitro. Additionally, treatment with exogenous recombinant mouse TSG-6 (rmTSG-6) demonstrated similar effects to BMSCs in attenuating silica-induced inflammation. Overall, our findings suggested that BMSCs can regulate the activation of inflammasome in macrophages by secreting TSG-6, thereby protecting against silica-induced acute pulmonary inflammation both in vivo and in vitro.

Labdane conjugates protect cardiomyocytes from doxorubicin-induced cardiotoxicity

The cardiovascular side effects associated with doxorubicin (DOX), a wide spectrum anticancer drug, have limited its clinical application. Therefore, to explore novel strategies with cardioprotective effects, a series of new labdane conjugates were prepared (6a-6c and 8a-8d) from the natural diterpene labdanodiol (1). These hybrid compounds contain anti-inflammatory privileged structures such as naphthalimide, naphthoquinone, and furanonaphthoquinone. Biological activity of these conjugates against DOX-induced cardiotoxicity was tested in vitro and the potential molecular mechanisms of protective effects were explored in H9c2 cardiomyocytes. Three compounds 6c, 8a, and 8b significantly improved cardiomyocyte survival, via inhibition of reactive oxygen species-mediated mitogen-activated protein kinase signaling pathways (extracellular signal-regulated kinase and c-Jun N-terminal kinase) and autophagy mediated by Akt activation. Some structure-activity relationships were outlined, and the best activity was achieved with the labdane-furonaphthoquinone conjugate 8a having an N-cyclohexyl substituent. The findings of this study pave the way for further investigations to obtain more compounds with potential cardioprotective activity.

Isoandrographolide from Andrographis paniculata ameliorates tubulointerstitial fibrosis in ureteral obstruction-induced mice, associated with negatively regulating AKT/GSK-3β/β-cat signaling pathway

Tubulointerstitial fibrosis (TIF) is a prominent pathological manifestation for the progression of almost all chronic kidney diseases (CKDs) to end-stage renal failure. However, there exist few efficient therapies to cure TIF. Our recent results showed that (8R, 12S)-isoandrographolide (ISA), a diterpenoid lactone ingredient of traditional Chinese herbal Andrographis paniculata (Burm.f.) Nees, exhibited anti-pulmonary fibrosis in silica-induced mice. Herein, we investigated the therapeutic effect of ISA on TIF, using mice subjected to unilateral ureteral obstruction (UUO) and human kidney proximal tubular epithelial (HK-2) cells treated with transforming growth factor-β1 (TGF-β1) or tumor necrosis factor-α (TNF-α). The pathological changes and collagen deposition results displayed that ISA administration significantly attenuated inflammatory response, ameliorated TIF, and protected the kidney injury. Interestingly, ISA revealed much lower cytotoxicity on HK-2 cells, but exhibited stronger inhibitory effect on tubular epithelial mesenchymal transformation (EMT) and inflammation, as compared to andrographolide (AD), the major ingredient of A. paniculata extract that has been reported to ameliorate TIF in diabetic nephropathy mice. It was further clarified that the amelioration of TIF by ISA was associated with suppressing the aberrant activation of AKT/GSK-3β/β-catenin pathway through network pharmacology analysis and experimental validation. Taken together, these findings indicate that ISA is a promising lead compound for development of anti-TIF, and even broad-spectrum anti-fibrotic drugs.

Dehydroisohispanolone as a Promising NLRP3 Inhibitor Agent: Bioevaluation and Molecular Docking

Dehydroisohispanolone (DIH), is a labdane diterpene that has exhibited anti-inflammatory activity via inhibition of NF-κB activation, although its potential effects on inflammasome activation remain unexplored. This study aims to elucidate whether DIH modulates NLR family pyrin domain-containing protein 3 (NLRP3) inflammasome in macrophages. Our findings show that DIH inhibited NLRP3 activation triggered by Nigericin (Nig), adenosine triphosphate (ATP) and monosodium urate (MSU) crystals, indicating broad inhibitory effects. DIH significantly attenuated caspase-1 activation and secretion of the interleukin-1β (IL-1β) in J774A.1 cells. Interestingly, the protein expressions of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), pro-caspase-1 and pro-IL-1β were not affected by DIH treatment. Furthermore, we found that DIH pretreatment also inhibited the lipopolysaccharide (LPS)-induced NLRP3 inflammasome priming stage. In addition, DIH alleviated pyroptosis mediated by NLRP3 inflammasome activation. Similar results on IL-1β release were observed in Nig-activated bone marrow-derived macrophages (BMDMs). Covalent molecular docking analysis revealed that DIH fits well into the ATP-binding site of NLRP3 protein, forming a covalent bond with Cys415. In conclusion, our experiments show that DIH is an effective NLRP3 inflammasome inhibitor and provide new evidence for its application in the therapy of inflammation-related diseases.