Araloside C attenuates atherosclerosis by modulating macrophage polarization via Sirt1-mediated autophagy

Phytochemicals Mediate Autophagy Against Osteoarthritis by Maintaining Cartilage Homeostasis

Osteoarthritis (OA) is a common degenerative joint disease and is a leading cause of disability and reduced quality of life worldwide. There are currently no clinical treatments that can stop or slow down OA. Drugs have pain-relieving effects, but they do not slow down the course of OA and their long-term use can lead to serious side effects. Therefore, safe and clinically appropriate long-term treatments for OA are urgently needed. Autophagy is an intracellular protective mechanism, and targeting autophagy-related pathways has been found to prevent and treat various diseases. Attenuation of the autophagic pathway has now been found to disrupt cartilage homeostasis and plays an important role in the development of OA. Therefore, modulation of autophagic signaling pathways mediating cartilage homeostasis has been considered as a potential therapeutic option for OA. Phytochemicals are active ingredients from plants that have recently been found to reduce inflammatory factor levels in cartilage as well as attenuate chondrocyte apoptosis by modulating autophagy-related signaling pathways, which are not only widely available but also have the potential to alleviate the symptoms of OA. We reviewed preclinical studies and clinical studies of phytochemicals mediating autophagy to regulate cartilage homeostasis for the treatment of OA. The results suggest that phytochemicals derived from plant extracts can target relevant autophagic pathways as complementary and alternative agents for the treatment of OA if subjected to rigorous clinical trials and pharmacological tests.

Recent advancement on development of drug-induced macrophage polarization in control of human diseases

Macrophages, an important part of human immune system, possess a high plasticity and heterogeneity (macrophage polarization) as classically activated macrophages (M1) and alternatively activated macrophages (M2), which exert pro-inflammatory/anti-tumor and anti-inflammatory/pro-tumor effects, respectively. Thus, drug development in induction of macrophage polarization could be used to treat different human diseases. This review summarizes the recent advancement on modulation of macrophage polarization and its related molecular mechanisms induced by a number of agents. Research on the anti-inflammatory drugs to regulate the macrophage polarization accounts for a large proportion in the field and types of diseases investigated could include atherosclerosis, enteritis, nephritis, and the nervous system and skeletal diseases, while study of the anti-tumor agents to modify macrophage polarization is a novel area of research. Future study of the molecular mechanisms by which the different agents regulate the macrophage polarization could lead to an effective control of various human diseases, including inflammation and cancers.

Mechanism of chlorogenic acid in alveolar macrophage polarization in Klebsiella pneumoniae-induced pneumonia

Chlorogenic acid (CA) has been discovered to regulate macrophage polarization in pneumonia. This study aims to analyze the functional mechanism of CA in alveolar macrophage (AM) polarization and provide a theoretical basis for treatment of Klebsiella pneumoniae (Kp)-induced pneumonia. Mice were infected with Kp, and treated with CA and silent information regulator 1 (SIRT1) inhibitor (Selisistat). Mouse survival rate was recorded and bacterial burden was detected. AM polarization and pathologic change of lung tissues were evaluated. Expressions of SIRT1 and HMGB1 and cytokine levels were detected. MH-S cells were infected with Kp to establish the pneumonia cell model, followed by transfection of si-SIRT1 and HMGB1 overexpression vector. The HMGB1 expression in the nucleus and cytoplasm was detected. HMGB1 subcellular localization and HMGB1 acetylation level were detected. Kp led to high death rates, SIRT down-regulation and increases in inflammatory factor level and bacterial burden, and promoted M1 polarization. CA treatment improved mouse survival rate and promoted M2 polarization and SIRT1 expression. SIRT1 decreased HMGB1 acetylation level to inhibit nuclear to the cytoplasm translocation. Silencing SIRT1 or HMGB1 overexpression reversed the effect of CA on Kp-induced pneumonia. Overall, CA activated SIRT1 to inhibit HMGB1 acetylation level and nuclear translocation, thereby promoting M2 polarization in AMs and alleviating Kp-induced pneumonia.

Overexpression of sFlt-1 represses ox-LDL-induced injury of HUVECs by activating autophagy via PI3K/AKT/mTOR pathway

Soluble fms-like tyrosine kinase-1 (sFlt-1), a circulating antiangiogenic protein, is involved in the pathogenesis of atherosclerosis (AS), and the underlying mechanism is still unclear. Here, we attempted to investigate the mechanism of action of sFlt-1 in AS. Human umbilical vein endothelial cells (HUVECs) were treated with oxidized low density lipoprotein (ox-LDL) to induce cell injury. ox-LDL treatment increased LC3-II/LC3-I ratio, Beclin-1 expression and GFP-LC3 puncta in HUVECs, suggesting that ox-LDL may induce autophagic flux impairment in HUVECs. ox-LDL-treated HUVECs displayed a decrease of sFlt-1 levels. Moreover, ox-LDL treatment reduced cell proliferation and elevated apoptosis in HUVECs, which was abrogated by sFlt-1 overexpression. Up-regulation of sFlt-1 repressed the activity of PI3K/AKT/mTOR signaling pathway and enhanced autophagy in HUVECs following ox-LDL treatment. Additionally, sFlt-1 overexpression-mediated increase of autophagy in ox-LDL-treated HUVECs was abolished by 3-methyladenine (autophagy inhibitor). 3-methyladenine abrogated the impact of sFlt-1 overexpression on proliferation and apoptosis in ox-LDL-treated HUVECs. This work confirmed that overexpression of sFlt-1 activated autophagy by repressing PI3K/Akt/mTOR signaling pathway, and thus alleviated ox-LDL-induced injury of HUVECs. Therefore, this study suggests that sFlt-1 may be a potential target for AS treatment.

MicroRNA-488 serves as a diagnostic marker for atherosclerosis and regulates the biological behavior of vascular smooth muscle cells

Atherosclerosis (AS) is one of the main causes of cerebral infarction. Researches on AS mainly focus on the gene level, among which microRNA is the research hotspot nowadays. This study investigated the diagnostic value of aberrant serum miR-488 in AS patients, and further explored the effect of abnormally expressed miR-488 on the biological behavior of vascular smooth muscle (VSMCs) cells by cell transfection. The qRT-PCR was used to investigate the expression level of miR-488 in 125 AS patients and 60 healthy controls. The diagnostic value of miR-488 was analyzed by the receiver operator characteristic (ROC) curve. CCK-8 and Transwell assays were used to detect the ability of miR-488 on the proliferation and migration ability of VSMCs cells. Serum expression of miR-488 in AS patients was higher than that in healthy controls. The expression level of miR-488 was significantly positively correlated with the Carotid Intima-Media Thickness (CIMT) value. The AUC of the ROC curve was 0.892, specificity was 99.3%, and sensitivity was 77.6%. In VSMCs cells, overexpression of miR-488 significantly promoted the proliferation and migration ability. The high expression of miR-488 is a good diagnostic marker for AS. The upregulation of miR-488 promotes VSMCs cell proliferation, and migration, which may provide a new theory for the treatment of AS.

Role of macrophage autophagy in atherosclerosis: modulation by bioactive compounds

Atherosclerosis is a chronic inflammatory disease associated with lipid metabolism disorder. Autophagy is a catabolic process and contributes to maintaining cellular homeostasis. Substantial evidence suggests that defective autophagy is implicated in several diseases, including atherosclerosis, while increased autophagy mitigates atherosclerosis development. Thus, understanding the mechanisms of autophagy regulation and its association with atherosclerosis is vital to develop new therapies against atherosclerosis. Dietary bioactive compounds are non-nutrient natural compounds that include phenolics, flavonoids, and carotenoids. Importantly, these bioactive compounds possess anti-inflammatory, antioxidant, and antibacterial properties that may alleviate various chronic diseases. Recently, examining the effects of bioactive compounds on autophagy activity in atherogenesis has drawn considerable attention. The current review discusses the role of macrophage autophagy in the development and progression of atherosclerosis. We also summarize our current knowledge of the therapeutic potential of bioactive compounds on atherosclerosis and autophagy.

Suppression of PAPP-A mitigates atherosclerosis by mediating macrophage polarization via STAT3 signaling

Pregnancy-associated plasma protein-A (PAPP-A), a type of metalloproteinase in the insulin-like growth factor (IGF) system, has been implicated in atherosclerosis progression, but its function and mechanism in atherosclerosis is not fully understood. The study was performed to further explore the effects of PAPP-A on inflammation, macrophage polarization and atherosclerosis. In mouse macrophages stimulated by oxidized low-density lipoprotein (ox-LDL), PAPP-A expression was significantly increased. Its knockdown markedly mitigated inflammatory response and polarized macrophages to an M2-like phenotype in RAW264.7 cells upon ox-LDL treatment. Additionally, ox-LDL-induced activation of nuclear factor-κB (NF-κB) signaling pathway was dramatically restricted by PAPP-A knockdown in macrophages. However, JAK2/STAT3 activation was significantly up-regulated in RAW264.7 cells with PAPP-A inhibition after ox-LDL treatment. Importantly, we found that PAPP-A knockdown-induced polarization of M2-like phenotype in macrophages was mainly dependent on STAT3 activation. Clinical studies showed that serum PAPP-A levels were higher in patients with coronary artery disease (CAD) than that of healthy individuals. Apolipoprotein E-knockout (ApoE^-/-) mice with high fat diet (HFD)-induced atherosclerosis exhibited higher expression of PAPP-A in aortas, which was mainly colocalized with F4/80. Subsequently, we found that PAPP-A deficiency greatly alleviated plaque formation, lesion burden and collagen accumulation in HFD-fed ApoE^-/- mice. Consistent with in vitro macrophage phenotype, PAPP-A^-/- reduced F4/80 expression, NF-κB activation and inflammatory response, while improved janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling and polarized macrophages to an M2-like phenotype in aortas of ApoE^-/- mice after HFD feeding. In conclusion, these findings identified PAPP-A as a positive regulator of atherosclerosis by regulating macrophage polarization via STAT3 signal, and thus could be considered as a potential therapeutic target for atherosclerosis treatment.

Gypenoside XVII alleviates early diabetic retinopathy by regulating Müller cell apoptosis and autophagy in db/db mice

Diabetic retinopathy (DR) is a widespread vision-threatening disease in working people. Müller cells are important glial cells that participate in the blood retinal barrier and promote the maintenance of retinal physiological and structural homeostasis. Müller cell apoptosis and autophagy play an important role in the pathogenesis of DR. Gypenoside XVII (Gyp-17) exerts strong antiapoptotic and autophagic activities. However, the effect of Gyp-17 on DR and its mechanism of action have not been elucidated. This study explored the effect of Gyp-17 on early DR and Müller cell injury in db/db mice. Blood glucose and blood lipids were measured. Optical coherence tomography and fundus fluorescein angiography were applied to detect retinal thickness and vascular leakage, respectively. Hematoxylin eosin staining assessed the pathological changes of the retina. Retinal oxidative environment and cell apoptosis and autophagy were monitored using commercial kits, immunofluorescence, and Western blot assays. Results showed that Gyp-17 exerted no significant effect on blood glucose and lipid levels but maintained normal retinal permeability, physiological structure, high anti-oxidative enzyme expression, and the thickness of the inner nuclear layer compared with the model group. Moreover, Western blot analysis and TUNEL assay indicated that Gyp-17 significantly decreased pro-apoptotic-related protein expression and increased pro-autophagy-related protein expression compared with the model group. Immunofluorescence colocalization exhibited that the regulating action of Gyp-17 may focus on Müller cells. These data strongly demonstrate that Gyp-17 prevents early DR by decreasing apoptosis and increasing autophagy in Müller cells. Gyp-17 may be a candidate drug for early DR therapy.

Ginsenoside Compound K Attenuates Ox-LDL-Mediated Macrophage Inflammation and Foam Cell Formation via Autophagy Induction and Modulating NF-κB, p38, and JNK MAPK Signaling

Atherosclerosis is a major reason for the high morbidity and mortality of cardiovascular diseases. Macrophage inflammation and foam cell formation are the key pathological processes of atherosclerosis. Ginsenoside compound K (CK) is a metabolite derived from ginseng. CK has anti atherosclerotic effect, but the molecular mechanism remains to be elucidated. We aim to explore the protective effect of CK against ox-LDL-induced inflammatory responses and foam cells formation in vitro and explore its potential mechanisms. Through the results of oil red O staining, Western blot, and qPCR, we found that CK significantly inhibited the foam cell formation, reduced the expression of SR-A1 and increased ABCA1 and ABCG1 expression. In addition, CK increased the number of autophagosomes and upregulated the LC3II/LC3I ratio and the expressions of ATG5 and Beclin-1 but decreased p62 expression. Moreover, CK significantly inhibited the NF-κB, p38, and JNK MAPK signaling pathway. Altogether, CK attenuated macrophage inflammation and foam cell formation via autophagy induction and by modulating NF-κB, p38, and JNK MAPK signaling. Thus, CK has potential as a therapeutic drug for atherosclerosis.

Knockdown of lncRNA HOXA-AS3 Suppresses the Progression of Atherosclerosis via Sponging miR-455-5p

Background

Atherosclerosis can lead to multiple cardiovascular diseases, especially myocardial infarction. Long noncoding RNAs (lncRNAs) are involved in multiple diseases, including atherosclerosis. LncRNA HOXA-AS3 was found to be notably upregulated in atherosclerosis. However, the biological function of HOXA-AS3 during the occurrence and development of atherosclerosis remains unclear.

Materials and Methods

Human vascular endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (oxLDL) to mimic atherosclerosis in vitro. Gene and protein expressions in HUVECs were detected by RT-qPCR and Western blot, respectively. Cell proliferation was tested by CCK-8 and Ki67 staining. Cell apoptosis and cycle were measured by flow cytometry. Additionally, the correlation between HOXA-AS3 and miR-455-5p was confirmed by dual luciferase report assay and RNA pull-down. Finally, in vivo model of atherosclerosis was established to confirm the function of HOXA-AS3 during the development of atherosclerosis in vivo.

Results

LncRNA HOXA-AS3 was upregulated in oxLDL-treated HUVECs. In addition, oxLDL-induced growth inhibition of HUVECs was significantly reversed by knockdown of HOXA-AS3. Consistently, oxLDL notably induced G1 arrest in HUVECs, while this phenomenon was greatly reversed by HOXA-AS3 siRNA. Furthermore, downregulation of HOXA-AS3 notably inhibited the progression of atherosclerosis through mediation of miR-455-5p/p27 Kip1 axis. Besides, silencing of HOXA-AS3 notably relieved the symptom of atherosclerosis in vivo.

Conclusion

Downregulation of HOXA-AS3 significantly suppressed the progression of atherosclerosis via regulating miR-455-5p/p27 Kip1 axis. Thus, HOXA-AS3 might serve as a potential target for the treatment of atherosclerosis.

Exosomes derived from mmu_circ_0000250-modified adipose-derived mesenchymal stem cells promote wound healing in diabetic mice by inducing miR-128-3p/SIRT1-mediated autophagy

More and more evidence advises that circular RNAs (circRNAs) function critically in regulating different disease microenvironments. Our previous study found that autotransplantation of adipose-derived mesenchymal stem cells (ADSCs) promotes diabetes wound healing. Exosomes derived in ADSCs play an important regulatory role. This study aimed to characterize if mmu_circ_0000250 played a role in ADSC-exosome-mediated full-thickness skin wound repair in diabetic rats. Endothelial progenitor cells (EPCs) were selected to study the therapeutic mechanism of exosomes in high-glucose (HG)-induced cell damage and dysfunction. Analysis and luciferase reporter assay were utilized to explore the interaction among mmu_circ_0000250, miRNA (miR)-128-3p, and sirtuin (SIRT)1. The diabetic rats were used to confirm the therapeutic effect of mmu_circ_0000250 against exosome-mediated wound healing. Exosomes containing a high concentration of mmu_circ_0000250 had a greater therapeutic effect on restoration of the function of EPCs by promotion autophagy activation under HG conditions. Expression of mmu_circ_0000250 promoted SIRT1 expression by miR-128-3p adsorption, which was confirmed via luciferase reporter assay and bioinformatics analysis. In vivo, exosomes containing a high concentration of mmu_circ_0000250 had a more therapeutic effect on wound healing when compared with wild-type exosomes from ADSCs. Immunohistochemistry and immunofluorescence detection showed that mmu_circ_0000250 increased angiopoiesis with exosome treatment in wound skin and suppressed apoptosis by autophagy activation. In conclusion, we verified that mmu_circ_0000250 enhanced the therapeutic effect of ADSC-exosomes to promote wound healing in diabetes by absorption of miR-128-3p and upregulation of SIRT1. Therefore, these findings advocate targeting the mmu_circ_0000250/miR-128-3p/SIRT1 axis as a candidate therapeutic option for diabetic ulcers.