Short Time Tripterine Treatment Enhances Endothelial Progenitor Cell Function via Heat Shock Protein 32

Combination Therapy with Resveratrol and Celastrol Using Folic Acid-Functionalized Exosomes Enhances the Therapeutic Efficacy of Sepsis

Overactivated macrophages are a prominent feature of many inflammatory and autoimmune diseases, including sepsis. Attention and regulation of macrophages activity is of great significance for sepsis treatment. Herein, this study shows that folic acid-functionalized exosomes accumulate in the lung of septic mice and specifically target inflammatory macrophages. Therefore, FA-functionalized exosomes co-loaded with resveratrol (an anti-inflammatory polyphenol) and celastrol (an immunosuppressive pentacyclic triterpenoid; FA-Exo/R+C), which exhibit powerful anti-inflammatory and immunosuppressive activities against LPS-stimulated macrophages in vitro by regulating NF-κB and ERK1/2 signaling pathways, are designed. Encouraged by these positive data, the efficacy of FA-Exo/R+C is systematically investigated in an LPS-induced mouse sepsis model. FA-Exo/R+C shows striking therapeutic benefits in terms of attenuated cytokine storm, reduced acute lung injury, and increased survival of septic mice by inhibiting the inflammation and proliferation of proinflammatory M1 macrophages. Importantly, multiple administrations of FA-Exo/R+C significantly enhance and prolong the protective effect, and resist rechallenge to LPS. Collectively, the strategy of co-delivering drugs combination through functionalized exosomes offers a new avenue for sepsis treatment.

lncRNA ANRIL accelerates wound healing in diabetic foot ulcers via modulating HIF1A/VEGFA signaling through interacting with FUS

BACKGROUND

Diabetic foot ulcer (DFU) is a frequently diagnosed complication of diabetes, and remains a heathcare burden worldwide. However, the pathogenesis of DFU is still largely unclear. The objective of this study is to delineate the function and underlying mechanism of lncRNA antisense non coding RNA in the INK4 locus (ANRIL) in endothelial progenitor cells (EPCs) and DFU mice.

METHODS

The DFU mouse model was established, and EPCs were subjected to high glucose (HG) treatment to mimic diabetes. qRT-PCR or western blot was employed to detected the expression of ANRIL, HIF1A, FUS and VEGFA. CCK-8 and Annexin V/PI staining were used to monitor cell proliferation and apoptosis. Wound healing, Transwell invasion and tube formation assays were conducted to assess cell migration, invasion and angiogenesis, respectively. The association between ANRIL and FUS was verified by RNA pull-down and RIP assays. Luciferase and ChIP assays were employed to investigate HIF1A-mediated transcriptional regulation of VEGFA and ANRIL. The histological alterations of DFU wound healing were observed by H&E and Masson staining.

RESULTS

ANRIL was downregulated in peripheral blood samples of DFU patients, DFU mice and HG-treated EPCs. Mechanistically, ANRIL regulated HIFA mRNA stability via recruiting FUS. VEGFA and ANRIL were transcriptionally regulated by HIF1A. Functional experiments revealed that HG suppressed EPC proliferation, migration, invasion and tube formation, but promoted apoptosis via ANRIL/HIF1A axis. ANRIL accelerated DFU wound healing via modulating HIF1A expression in vivo.

CONCLUSION

ANRIL accelerated wound healing in DFU via modulating HIF1A/VEGFA signaling in a FUS-dependent manner.

Transplantation of Endothelial Progenitor Cells: Summary and prospect

Endothelial Progenitor Cells (EPCs) are precursor cells of endothelial cells (ECs), which can differentiate into vascular ECs, protect from endothelial dysfunction and tissue ischemia, and reduce vascular hyperplasia. Due to these functions, EPCs are used as a candidate cell source for transplantation strategies. In recent years, a great progress was achieved in EPCs biology research, and EPCs transplantation has become a research hotspot. At present, transplanted EPCs have been used to treat ischemic diseases due to their powerful vasculogenesis and beneficial paracrine effects. Although EPCs transplantation has been proved to play an important role, the clinical application of EPCs still faces many challenges. This review briefly summarized the basic characteristics of EPCs, the process of EPCs transplantation promoting the healing of ischemic tissue, and the ways to improve the efficiency of EPCs transplantation. In addition, the application of EPCs in neurological improvement, cardiovascular and respiratory diseases and the challenges and problems in clinical application of EPCs were also discussed. In the end, the application of EPCs transplantation in regenerative medicine and tissue engineering was discussed.

Hsp20 Promotes Endothelial Progenitor Cell Angiogenesis via Activation of PI3K/Akt Signaling Pathway under Hypoxia

BACKGROUND

Mandibular distraction osteogenesis (MDO) is a kind of endogenous tissue engineering technology that lengthens the jaw and opens airway so that a patient can breathe safely and comfortably on his or her own. Endothelial progenitor cells (EPCs) are crucial for MDO-related angiogenesis. Moreover, emerging evidence suggests that heat shock protein 20 (Hsp20) modulates angiogenesis under hypoxic conditions. However, the specific role of Hsp20 in EPCs, in the context of MDO, is not yet known. The aim of this study was to explore the expression of Hsp20 during MDO and the effects of Hsp20 on EPCs under hypoxia.

METHODS

Mandibular distraction osteogenesis and mandibular bone defect (MBD) canine model were established. The expression of CD34, CD133, HIF-1α, and Hsp20 in callus was detected by immunofluorescence on day 14 after surgery. Canine bone marrow EPCs were cultured, with or without optimal cobalt chloride (CoCl2) concentration. Hypoxic effects, caused by CoCl2, were evaluated by means of the cell cycle, cell apoptosis, transwell cell migration, and tube formation assays. The Hsp20/KDR/PI3K/Akt expression levels were evaluated via immunofluorescence, RT-qPCR, and western blot. Next, EPCs were incorporated with either Hsp20-overexpression or Hsp20-siRNA lentivirus. The resulting effects were evaluated as described above.

RESULTS

CD34, CD133, HIF-1α, and Hsp20 were displayed more positive in the callus of MDO compared with MBD. In addition, hypoxic conditions, generated by 0.1 mM CoCl2, in canine EPCs, accelerated cell proliferation, migration, tube formation, and Hsp20 expression. Hsp20 overexpression in EPCs significantly stimulated cell proliferation, migration, and tube formation, whereas Hsp20 inhibition produced the opposite effect. Additionally, the molecular mechanism was partly dependent on the KDR/PI3K/Akt pathway.

CONCLUSION

In summary, herein, we present a novel mechanism of Hsp20-mediated regulation of canine EPCs via Akt activation in a hypoxic microenvironment.

Neuroprotective Effects of Celastrol in Neurodegenerative Diseases-Unscramble Its Major Mechanisms of Action and Targets

There are rarely new therapeutic breakthroughs present for neurodegenerative diseases in the last decades. Thus, new effective drugs are urgently needed for millions of patients with neurodegenerative diseases. Celastrol, a pentacyclic triterpenoid compound, is one of the main active ingredients isolated from Tripterygium wilfordii Hook. f. that has multiple biological activities. Recently, amount evidence indicates that celastrol exerts neuroprotective effects and holds therapeutic potential to serve as a novel agent for neurodegenerative diseases. This review focuses on the therapeutic efficacy and major regulatory mechanisms of celastrol to rescue damaged neurons, restore normal cognitive and sensory motor functions in neurodegenerative diseases. Importantly, we highlight recent progress regarding identification of the drug targets of celastrol by using advanced quantitative chemical proteomics technology. Overall, this review provides novel insights into the pharmacological activities and therapeutic potential of celastrol for incurable neurodegenerative diseases.

New insight into dyslipidemia‐induced cellular senescence in atherosclerosis

Atherosclerosis, characterized by lipid‐rich plaques in the arterial wall, is an age‐related disorder and a leading cause of mortality worldwide. However, the specific mechanisms remain complex. Recently, emerging evidence has demonstrated that senescence of various types of cells, such as endothelial cells (ECs), vascular smooth muscle cells (VSMCs), macrophages, endothelial progenitor cells (EPCs), and adipose‐derived mesenchymal stem cells (AMSCs) contributes to atherosclerosis. Cellular senescence and atherosclerosis share various causative stimuli, in which dyslipidemia has attracted much attention. Dyslipidemia, mainly referred to elevated plasma levels of atherogenic lipids or lipoproteins, or functional impairment of anti‐atherogenic lipids or lipoproteins, plays a pivotal role both in cellular senescence and atherosclerosis. In this review, we summarize the current evidence for dyslipidemia‐induced cellular senescence during atherosclerosis, with a focus on low‐density lipoprotein (LDL) and its modifications, hydrolysate of triglyceride‐rich lipoproteins (TRLs), and high‐density lipoprotein (HDL), respectively. Furthermore, we describe the underlying mechanisms linking dyslipidemia‐induced cellular senescence and atherosclerosis. Finally, we discuss the senescence‐related therapeutic strategies for atherosclerosis, with special attention given to the anti‐atherosclerotic effects of promising geroprotectors as well as anti‐senescence effects of current lipid‐lowering drugs.

Guidelines and standards for comprehensive clinical diagnosis and interventional treatment for diabetic foot in China (Issue 7.0)

Diabetic foot (DF) is one of the most common complications of diabetes and is associated with high morbidity, disability, lethality and low cure-rate. The clinical diagnosis and treatment of DF need to be standardized. The Chinese Diabetic Foot Cell and Interventional Therapy Technology Alliance has released six editions of guidelines and standards for clinical diagnosis and interventional treatment of DF, which filled the gap in the domestic DF treatment standard and played an important role in improving the level of diagnosis and treatment in China. In line with the latest developments in diagnosis and treatment, the Alliance, along with other 89 institutions, developed and issued the new edition based on the sixth edition to help standardize the clinical diagnosis and treatment of DF in China.

Celastrol in metabolic diseases: Progress and application prospects

Metabolic diseases are becoming increasingly common in modern society. Therefore, it is essential to develop effective drugs or new treatments for metabolic diseases. As an active ingredient derived from plants, celastrol has shown great potential in the treatment of a wide variety of metabolic diseases and received considerable attention in recent years. In reported studies, the anti-obesity effect of celastrol resulted from regulating leptin sensitivity, energy metabolism, inflammation, lipid metabolism and even gut microbiota. Celastrol reversed insulin resistance via multiple routes to protect against type 2 diabetes. Celastrol also showed effects on atherosclerosis, cholestasis and osteoporosis. Celastrol in treating metabolic diseases seem to be versatile and the targets or pathways were diverse. Here, we systematically review the mechanism of action, and the therapeutic properties of celastrol in various metabolic diseases and complications. Based on this review, potential research strategies might contribute to the celastrol's clinical application in the future.

TUG1 enhances high glucose-impaired endothelial progenitor cell function via miR-29c-3p/PDGF-BB/Wnt signaling

BACKGROUND

Diabetes is associated with the dysfunction of endothelial progenitor cells (EPCs), characterized as impaired angiogenesis, a phenomenon thought to be involved in the development of diabetic foot. lncRNA plays an essential role in microvascular dysfunction and signaling pathways in patients with diabetes. lncRNA taurine upregulated gene 1 (TUG1) participates in angiogenesis in various cells. However, the mechanisms of TUG1 activity in EPCs have not been elucidated.

METHODS

We isolated and then characterized EPCs from the peripheral blood of mice using immunofluorescence and flow cytometry. Western blot detected the wnt/β-catenin pathway in high glucose-treated EPCs. Bioinformatics analysis predicted a putative binding site for TUG1 on miR-29c-3p. The interactions among TUG1, platelet-derived growth factor-BB (PDGF-BB), and miR-29c-3p were analyzed by luciferase assays. In vivo, diabetic mouse ischemic limb was treated with normal saline or TUG1 overexpression lentiviruses.

RESULTS

We found that EPC migration, invasion, and tube formation declined after treatment with high glucose, but improved with TUG1 overexpression. Mechanically, wnt/β-catenin pathway and autophagy were involved in the function of TUG1 overexpression in high glucose-treated EPCs. Moreover, TUG1 regulates the PDGF-BB/wnt pathway and function of high glucose-treated EPCs via miR-29c-3p. In vivo, injection of TUG1 lentivirus in a diabetic mouse ischemic limb model stimulated angiogenesis.

CONCLUSIONS

Our findings suggest that TUG1 restores high glucose-treated EPC function by regulating miR-29c-3p/PDGF-BB/Wnt signaling.

Exogenous FGF-2 improves biological activity of endothelial progenitor cells exposed to high glucose conditions

Purpose: To investigate the effects of exogenous basic fibroblast growth factor -2 (FGF-2) on the biological activity of endothelial progenitor cells (EPCs) exposed to high glucose conditions.

Materials and Methods: 1) Bone marrow EPCs from C57BL/6 mice were isolated and cultured in vitro. EPC purity was identified by flow cytometry and immunofluorescence staining. 2) Apoptosis was detected by TUNEL assay. Migration and tube formation ability was detected by Transwell chamber and Matrigel assays, respectively. The expression and activation of β-catenin was detected by Western blot. 3) Doppler flowmetry was used to detect the effect of FGF2 on blood flow recovery in ischemic hind limbs of mice.

Results: 1) FGF-2 treatment reversed high glucose induced growth inhibition of EPCs. FGF-2 treatment also increased migration and tube formation ability of EPCs even in high glucose conditions. 2) Western blot analysis demonstrated that the percentage of activated β-catenin/total β-catenin in the high glucose group were significantly lower than that in the control group, while FGF-2 treatment reversed high glucose induced β-catenin inhibition. 3) In vivo experiments demonstrated that the blood flow recovery in ischemic hind limbs of mice was significantly improved after FGF-2 treatment.

Conclusion: Exogenous FGF-2 could play a role in the functional repair of damaged EPC exposed to high glucose conditions, via the activation of the Wnt/β-catenin signaling pathway.

Shear stress: An essential driver of endothelial progenitor cells

The blood flow through vessels produces a tangential, or shear, stress sensed by their innermost layer (i.e., endothelium) and representing a major hemodynamic force. In humans, endothelial repair and blood vessel formation are mainly performed by circulating endothelial progenitor cells (EPCs) characterized by a considerable expression of vascular endothelial growth factor receptor 2 (VEGFR2), CD34, and CD133, pronounced tube formation activity in vitro, and strong reendothelialization or neovascularization capacity in vivo. EPCs have been proposed as a promising agent to induce reendothelialization of injured arteries, neovascularization of ischemic tissues, and endothelialization or vascularization of bioartificial constructs. A number of preconditioning approaches have been suggested to improve the regenerative potential of EPCs, including the use of biophysical stimuli such as shear stress. However, in spite of well-defined influence of shear stress on mature endothelial cells (ECs), articles summarizing how it affects EPCs are lacking. Here we discuss the impact of shear stress on homing, paracrine effects, and differentiation of EPCs. Unidirectional laminar shear stress significantly promotes homing of circulating EPCs to endothelial injury sites, induces anti-thrombotic and anti-atherosclerotic phenotype of EPCs, increases their capability to form capillary-like tubes in vitro, and enhances differentiation of EPCs into mature ECs in a dose-dependent manner. These effects are mediated by VEGFR2, Tie2, Notch, and β1/3 integrin signaling and can be abrogated by means of complementary siRNA/shRNA or selective pharmacological inhibitors of the respective proteins. Although the testing of sheared EPCs for vascular tissue engineering or regenerative medicine applications is still an unaccomplished task, favorable effects of unidirectional laminar shear stress on EPCs suggest its usefulness for their preconditioning.

Celastrol alleviates angiotensin II‑mediated vascular smooth muscle cell senescence via induction of autophagy

Reactive oxygen species (ROS) production has been implicated in the promotion of cellular senescence. Celastrol, a quinone methide triterpenoid isolated from the Celastraceae family, exerts antioxidant effects and enhances autophagy in various cell types. Since autophagy serves an important role in regulating ROS, it was hypothesized that the antioxidant effect of celastrol is via enhanced autophagy, thus inhibiting cell senescence. Therefore, the present study used a Senescence β‑Galactosidase Staining kit, western blot analysis and cell cycle analysis to investigate whether celastrol alleviates angiotensin (Ang) II‑induced cellular senescence by upregulating autophagy in vascular smooth muscle cells (VSMCs). The results demonstrated that celastrol reduced Ang II‑induced senescence of VSMCs. Ang II‑induced generation of ROS and the subsequent VSMC senescence were counteracted by pretreatment with celastrol, determined by a ROS assay kit. Celastrol significantly upregulated VSMC autophagy, which reduced intracellular ROS and the subsequent cellular senescence induced by Ang II. Furthermore, celastrol markedly suppressed activity of the mechanistic target of rapamycin signaling pathway in VSMCs. In conclusion, the present study demonstrated that celastrol counteracts VSMC senescence probably by reducing ROS production via activation of autophagy, which may hold promise for the prevention and treatment of aging‑associated cardiovascular disorders such as atherosclerosis.

Celastrol: A Spectrum of Treatment Opportunities in Chronic Diseases

The identification of new bioactive compounds derived from medicinal plants with significant therapeutic properties has attracted considerable interest in recent years. Such is the case of the Tripterygium wilfordii (TW), an herb used in Chinese medicine. Clinical trials performed so far using its root extracts have shown impressive therapeutic properties but also revealed substantial gastrointestinal side effects. The most promising bioactive compound obtained from TW is celastrol. During the last decade, an increasing number of studies were published highlighting the medicinal usefulness of celastrol in diverse clinical areas. Here we systematically review the mechanism of action and the therapeutic properties of celastrol in inflammatory diseases, namely, rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel diseases, osteoarthritis and allergy, as well as in cancer, neurodegenerative disorders and other diseases, such as diabetes, obesity, atherosclerosis, and hearing loss. We will also focus in the toxicological profile and limitations of celastrol formulation, namely, solubility, bioavailability, and dosage issues that still limit its further clinical application and usefulness.

Celastrol attenuates angiotensin II mediated human umbilical vein endothelial cells damage through activation of Nrf2/ERK1/2/Nox2 signal pathway

Angiotensin II (Ang II), as a crucial factor of endothelial dysfunction, participates in endothelial oxidative damage and inflammation, which is present in all cardiovascular disease (CVD). Celastrol, extracted from Trypterygiun wilfordii Hook F. ("Thunder of God Vine"), is a natural compound with antioxidant and anti-inflammatory activities. In this study, the protective effects of celastrol on human umbilical vein endothelial cell (HUVEC) injury induced by Ang II were observed and its mechanisms were elucidated. Compared with the control group, Ang II significantly increased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, enhanced reactive oxygen species levels and proinflammatory cytokines, decreased antioxidant enzyme activities, and suppressed cellular viability and promoted cell apoptosis. It accomplished this via inhibition of the nuclear factor erythroid 2-related factor 2 (Nrf2), increasing the expression levels of Nox2 and AngII type 1 receptor (AT₁ receptor), and inducing the phosphorylation of extracellular signal regulated kinase (ERK1/2). In contrast, celastrol effectively suppressed reactive oxygen species generation, improved endothelial cell activity, and ameliorated Ang II-mediated HUVEC injury through activation of Nrf2, inhibition of Nox2/AT₁ receptor expression, and upregulated phosphorylation of ERK1/2. After treatment with brusatol, a specific inhibitor of Nrf2, the protective effects of celastrol on Ang II-induced damage in HUVECs were remarkably alleviated. Taken together, celastrol-induced activation of Nrf2 and inhibition of NADPH oxidase activity were critical for the inhibition of Ang II-mediated endothelial dysfunction, and demonstrated the potential application of celastrol in CVD therapy.

Celastrol targets IRAKs to block Toll-like receptor 4-mediated nuclear factor-κB activation

OBJECTIVE

Celastrol has been established as a nuclear factor-κB (NF-κB) activation inhibitor; however, the exact mechanism behind this action is still unknown. Using text-mining technology, the authors predicted that interleukin-1 receptor-associated kinases (IRAKs) are potential celastrol targets, and hypothesized that targeting IRAKs might be one way that celastrol inhibits NF-κB. This is because IRAKs are key molecules for some crucial pathways to activate NF-κB (e.g., the interleukin-1 receptor (IL-1R)/Toll-like receptor (TLR) superfamily).

METHODS

The human hepatocellular cell line (HepG2) treated with palmitic acid (PA) was used as a model for stimulating TLR4/NF-κB activation, in order to observe the potential effects of celastrol in IRAK regulation and NF-κB inhibition. The transfection of small interfering RNA was used for down-regulating TLR4, IRAK1 and IRAK4, and the Western blot method was used to detect changes in the protein expressions.

RESULTS

The results showed that celastrol could effectively inhibit PA-caused TLR4-dependent NF-κB activation in the HepG2 cells; PA also activated IRAKs, which were inhibited by celastrol. Knocking down IRAKs abolished PA-caused NF-κB activation.

CONCLUSION

The results for the first time show that targeting IRAKs is one way in which celastrol inhibits NF-κB activation.

BM ageing: Implication for cell therapy with EPCs

The bone marrow (BM) is a well-recognized source of stem/progenitor cells for cell therapy in cardiovascular diseases (CVDs). Preclinical and clinical studies suggest that endothelial progenitor cells (EPCs) contribute to reparative process of vascular endothelium and participate in angiogenesis. As for all organs and cells across the lifespan, BM and EPCs are negatively impacted by ageing due to microenvironment modifications and EPC progressive dysfunctions. The encouraging results in terms of neovascularization observed in young animals after EPC administration were mitigated in aged patients treated for ischemic CVDs. The limited efficacy of EPC-based therapy in clinical setting might be ascribed at least partly to ageing. In this review, we comprehensively discussed the age-related changes of BM and EPCs and their implication for cardiovascular cell-therapies. Finally, we examined alternative approaches under investigation to enhance EPC potency.