Dihydroartemisinin alleviates skin fibrosis and endothelial dysfunction in bleomycin-induced skin fibrosis models

Recent Insights into Cellular and Molecular Mechanisms of Defective Angiogenesis in Systemic Sclerosis

In systemic sclerosis (SSc, or scleroderma), defective angiogenesis, clinically manifesting with abnormal capillary architecture and severe capillary reduction, represents a hallmark of early-stage disease, usually preceding the onset of tissue fibrosis, and is caused by several cellular and molecular mechanisms affecting microvascular endothelial cells with different outcomes. Indeed, once damaged, endothelial cells can be dysfunctionally activated, thus becoming unable to undergo angiogenesis and promoting perivascular inflammation. They can also undergo apoptosis, transdifferentiate into profibrotic myofibroblasts, or acquire a senescence-associated secretory phenotype characterized by the release of exosomes and several profibrotic and proinflammatory mediators. In this narrative review, we aimed to give a comprehensive overview of recent studies dealing with the cellular and molecular mechanisms underlying SSc defective angiogenesis and the related endothelial cell dysfunctions, mainly the endothelial-to-mesenchymal transition process. We also discussed potential novel vascular treatment strategies able to restore the angiogenic process and reduce the endothelial-to-mesenchymal transition in this complex disease.

Costic acid, a sesquiterpene from Nectandra barbellata (Lauraceae), attenuates sponge implant-induced inflammation, angiogenesis and collagen deposition in vivo

Sesquiterpenes are a class of metabolites derived from plant species with immunomodulatory activity. In this study, we evaluated the effects of treatment with costic acid on inflammation, angiogenesis, and fibrosis induced by subcutaneous sponge implants in mice. One sponge disc per animal was aseptically implanted in the dorsal region of the mice and treated daily with costic acid (at concentrations of 0.1, 1, and 10 μg diluted in 10 μL of 0.5% DMSO) or 0.5% DMSO (control group). After 9 days of treatment, the animals were euthanized, and the implants collected for further analysis. Treatment with costic acid resulted in the reduction of the inflammatory parameters evaluated compared to the control group, with a decrease in the levels of inflammatory cytokines and chemokines (TNF, CXCL-1, and CCL2) and in the activity of MPO and NAG enzymes. Costic acid administration altered the process of mast cell degranulation. We also observed a reduction in angiogenic parameters, such as a decrease in the number of blood vessels, the hemoglobin content, and the levels of VEGF and FGF cytokines. Finally, when assessing implant-induced fibrogenesis, we observed a reduction in the levels of the pro-fibrogenic cytokine TGF-β1, and lower collagen deposition. The results of this study demonstrate, for the first time, the anti-inflammatory, anti-angiogenic, and anti-fibrotic effects of costic acid in an in vivo model of chronic inflammation and reinforce the therapeutic potential of costic acid.

Differential Anti-Fibrotic and Remodeling Responses of Human Dermal Fibroblasts to Artemisia sp., Artemisinin, and Its Derivatives

Fibrosis is a ubiquitous pathology, and prior studies have indicated that various artemisinin (ART) derivatives (including artesunate (AS), artemether (AM), and dihydroartemisinin (DHA)) can reduce fibrosis in vitro and in vivo. The medicinal plant Artemisia annua L. is the natural source of ART and is widely used, especially in underdeveloped countries, to treat a variety of diseases including malaria. A. afra contains no ART but is also antimalarial. Using human dermal fibroblasts (CRL-2097), we compared the effects of A. annua and A. afra tea infusions, ART, AS, AM, DHA, and a liver metabolite of ART, deoxyART (dART), on fibroblast viability and expression of key fibrotic marker genes after 1 and 4 days of treatment. AS, DHA, and Artemisia teas reduced fibroblast viability 4 d post-treatment in up to 80% of their respective controls. After 4 d of treatment, AS DHA and Artemisia teas downregulated ACTA2 up to 10 fold while ART had no significant effect, and AM increased viability by 10%. MMP1 and MMP3 were upregulated by AS, 17.5 and 32.6 fold, respectively, and by DHA, 8 and 51.8 fold, respectively. ART had no effect, but A. annua and A. afra teas increased MMP3 5 and 16-fold, respectively. Although A. afra tea increased COL3A1 5 fold, MMP1 decreased >7 fold with no change in either transcript by A. annua tea. Although A. annua contains ART, it had a significantly greater anti-fibrotic effect than ART alone but was less effective than A. afra. Immunofluorescent staining for smooth-muscle α-actin (α-SMA) correlated well with the transcriptional responses of drug-treated fibroblasts. Together, proliferation, qPCR, and immunofluorescence results show that treatment with ART, AS, DHA, and the two Artemisia teas yield differing responses, including those related to fibrosis, in human dermal fibroblasts, with evidence also of remodeling of fibrotic ECM.

The contribution of endothelial cells to tissue fibrosis

PURPOSE OF REVIEW

Tissue fibrosis is an increasingly prevalent condition associated with various diseases and heavily impacting on global morbidity and mortality rates. Growing evidence indicates that common cellular and molecular mechanisms may drive fibrosis of diverse cause and affecting different organs. The scope of this review is to highlight recent findings in support for an important role of vascular endothelial cells in the pathogenesis of fibrosis, with a special focus on systemic sclerosis as a prototypic multisystem fibrotic disorder.

RECENT FINDINGS

Although transition of fibroblasts to chronically activated myofibroblasts is widely considered the central profibrotic switch, the endothelial cell involvement in development and progression of fibrosis has been increasingly recognized over the last few years. Endothelial cells can contribute to the fibrotic process either directly by acting as source of myofibroblasts through endothelial-to-myofibroblast transition (EndMT) and concomitant microvascular rarefaction, or indirectly by becoming senescent and/or secreting a variety of profibrotic and proinflammatory mediators with consequent fibroblast activation and recruitment of inflammatory/immune cells that further promote fibrosis.

SUMMARY

An in-depth understanding of the mechanisms underlying EndMT or the acquisition of a profibrotic secretory phenotype by endothelial cells will provide the rationale for novel endothelial cell reprogramming-based therapeutic approaches to prevent and/or treat fibrosis.

Jia-Wei-Si-Miao-Yong-An Fang stimulates the healing of acute radiation-induced cutaneous wounds through MAPK/ERK pathway

ETHNOPHARMACOLOGICAL RELEVANCE

A famous traditional oral Chinese medicine formula, Si-Miao-Yong-An decoction, has been used to treat thromboangiitis obliterans from the Qing Dynasty. Because its therapeutic principles including clearing away heat, detoxification, accelerating blood circulation and relieving pains are consistent with acute radiation-induced cutaneous wounds in traditional Chinese medicine, we tried to add herbs and improve them into an external dosage form, called Jia-Wei-Si-Miao-Yong-An Fang (JWSMYA). However, its mechanism on radiation-induced cutaneous wounds is still unknown.

AIM OF THE STUDY

This study evaluated the therapeutic effect of JWSMYA and investigated the mechanism of repair and anti-fibrosis on acute radiation-induced cutaneous wounds with JWSMYA.

MATERIALS AND METHODS

Firstly, we prepared JWSMYA, and determined the composition through UHPLC LC-MS/MS. Then we used ionizing radiation to make a cutaneous wound model of rats, and observed wound healing through their skin injury score, wound contraction percentage and histological staining. In addition, immunohistochemical staining, Western blot analysis, qRT-PCR and Elisa were used to explore wound rehabilitation and anti-fibrosis mechanisms.

RESULTS

An in vivo assay revealed that JWSMYA promoted the repairment of acute radiation-induced cutaneous wounds, facilitated MAPK/ERK phosphorylation, inhibited PI3K/AKT activation, reduced the level of alpha-smooth muscle actin (a-sma), collagen type-I alpha 2 (Col1a2) and transforming growth factor-beta 1 (TGF-β1) in cutaneous tissues. However, no statistical difference was found in vascular endothelial growth factor (VEGF).

CONCLUSION

JWSMYA accelerated the repair of acute radiation-induced cutaneous wounds, which might be associated with the MAPK/ERK pathway. In addition, PI3K/AKT might be associated with the inhibition of fibrosis and the promotion of high-quality wound healing.

Dihydroartemisinin Exerts Antifibrotic and Anti-Inflammatory Effects in Graves' Ophthalmopathy by Targeting Orbital Fibroblasts

Graves' ophthalmopathy (GO) is a common orbital disease that threatens visual function and appearance. Orbital fibroblasts (OFs) are considered key target and effector cells in GO. In addition, hyaluronan (HA) production, inflammation, and orbital fibrosis are intimately linked to the pathogenesis of GO. In this study, we explored the therapeutic effects of dihydroartemisinin (DHA), an antimalarial drug, on GO-derived, primary OFs. CCK8 and EdU assays were applied to evaluate the antiproliferative effect of DHA on OFs. Wound healing assays were conducted to assess OF migration capacity, while qRT-PCR, western blotting, ELISA, and immunofluorescence were used to determine the expression of fibrosis-related and pro-inflammatory markers in these cells. Moreover, RNA sequencing was conducted to identify differentially expressed genes (DEGs) in DHA-treated OFs, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs was performed to explore potential mechanisms mediating the antifibrotic effect of DHA on GO-derived OFs. Results showed that DHA dose-dependently inhibited OF proliferation and downregulated, at the mRNA and protein levels, TGF-β1-induced expression of fibrosis markers, including alpha smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF). Furthermore, DHA inhibited TGF-β1 induced phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3), which suggested that DHA exerted antifibrotic effects via suppression of the ERK and STAT3 signaling pathways. In addition, DHA suppressed the expression of pro-inflammatory cytokines and chemokines, including IL-6, IL-8, CXCL-1, MCP-1, and ICAM-1, and attenuated HA production induced by IL-1β in GO-derived OFs. In conclusion, our study provides first-time evidence that DHA may significantly alleviate pathogenic manifestations of GO by inhibiting proliferation, fibrosis- and inflammation-related gene expression, and HA production in OFs. These data suggest that DHA may be a promising candidate drug for treatment of GO.

Dihydroartemisinin improves hypercholesterolemia in ovariectomized mice via enhancing vectorial transport of cholesterol and bile acids from blood to bile

The increase of concentrations of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in the serum of postmenopausal women is the important risk factor of the high morbidity of cardiovascular diseases of old women worldwide. To test the anti-hypercholesterolemia function of dihydroartemisinin (DHA) in postmenopausal women, ovariectomized (OVX) mice were generated, and DHA were administrated to OVX mice for 4 weeks. The blood and liver tissues were collected for biochemical and histological tests respectively. The mRNA and protein expression levels of genes related to metabolism and transport of cholesterol, bile acid and fatty acid in the liver or ileum were checked through qPCR and western blot. DHA could significantly reduce the high concentrations of TC and LDL-C in the serum and the lipid accumulation in the liver of ovariectomized mice. The expression of ABCG5/8 was reduced in liver of OVX mice, and DHA could up-regulate the expression of them. Genes of transport proteins for bile salt transport from blood to bile, including Slc10a1, Slco1b2 and Abcb11, were also significantly up-regulated by DHA. DHA also down-regulated the expression of Slc10a2 in the ileum of OVX mice to reduce the absorption of bile salts. Genes required for fatty acid synthesis and uptake, such as Fasn and CD36, were reduced in the liver of OVX mice, and DHA administration could significantly up-regulate the expression of them. These results demonstrated that DHA could improve hypercholesterolemia in OVX mice through enhancing the vectorial transport of cholesterol and bile acid from blood to bile.

The Impact of Inflammatory Immune Reactions of the Vascular Niche on Organ Fibrosis

Inflammation is a type of defense response against tissue damage, and can be mediated by lymphocytes and macrophages. Fibrosis is induced by tissue injury and inflammation, which leads to an increase in fibrous connective tissue in organs and a decrease in organ parenchyma cells, finally leading to organ dysfunction or even failure. The vascular niche is composed of endothelial cells, pericytes, macrophages, and hematopoietic stem cells. It forms a guiding microenvironment for the behavior of adjacent cells, and mainly exists in the microcirculation, including capillaries. When an organ is damaged, the vascular niche regulates inflammation and affects the repair of organ damage in a variety of ways, such as via its angiocrine function and transformation of myofibroblasts. In this paper, the main roles of vascular niche in the process of organ fibrosis and its mechanism of promoting the progress of fibrosis through inflammatory immunoregulation are summarized. It was proposed that the vascular niche should be regarded as a new therapeutic target for organ fibrosis, suggesting that antifibrotic effects could be achieved by regulating macrophages, inhibiting endothelial-mesenchymal transition, interfering with the angiocrine function of endothelial cells, and inhibiting the transformation of pericytes into myofibroblasts, thus providing new ideas for antifibrosis drug research.