Rapamycin inhibits oxidative/nitrosative stress and enhances angiogenesis in high glucose-treated human umbilical vein endothelial cells: Role of autophagy

Biosensors; a novel concept in real-time detection of autophagy

Autophagy is an early-stage response with self-degradation properties against several insulting conditions. To date, the critical role of autophagy has been well-documented in physiological and pathological conditions. This process involves various signaling and functional biomolecules, which are involved in different steps of the autophagic response. During recent decades, a range of biochemical analyses, chemical assays, and varied imaging techniques have been used for monitoring this pathway. Due to the complexity and dynamic aspects of autophagy, the application of the conventional methodology for following autophagic progression is frequently associated with a mistake in discrimination between a complete and incomplete autophagic response. Biosensors provide a de novo platform for precise and accurate analysis of target molecules in different biological settings. It has been suggested that these devices are applicable for real-time monitoring and highly sensitive detection of autophagy effectors. In this review article, we focus on cutting-edge biosensing technologies associated with autophagy detection.

STING agonists as promising vaccine adjuvants to boost immunogenicity against SARS-related coronavirus derived infection: possible role of autophagy

As a major component of innate immunity and a positive regulator of interferons, the Stimulator of interferon gene (STING) has an immunotherapy potential to govern a variety of infectious diseases. Despite the recent advances regarding vaccines against COVID-19, nontoxic novel adjuvants with the potential to enhance vaccine efficacy are urgently desired. In this connection, it has been well-documented that STING agonists are applied to combat COVID-19. This approach is of major significance for boosting immune responses most likely through an autophagy-dependent manner in susceptible individuals against infection induced by severe acute respiratory syndrome Coronavirus (SARS‑CoV‑2). Given that STING agonists exert substantial immunomodulatory impacts under a wide array of pathologic conditions, these agents could be considered novel adjuvants for enhancing immunogenicity against the SARS-related coronavirus. Here, we intend to discuss the recent advances in STING agonists' recruitment to boost innate immune responses upon vaccination against SARS-related coronavirus infections. In light of the primordial role of autophagy modulation, the potential of being an antiviral vaccine adjuvant was also explored.

JunB condensation attenuates vascular endothelial damage under hyperglycemic condition

Endothelial damage is the initial and crucial factor in the occurrence and development of vascular complications in diabetic patients, contributing to morbidity and mortality. Although hyperglycemia has been identified as a damaging effector, the detailed mechanisms remain elusive. In this study, identified by ATAC-seq and RNA-seq, JunB reverses the inhibition of proliferation and the promotion of apoptosis in human umbilical vein endothelial cells treated with high glucose, mainly through the cell cycle and p53 signaling pathways. Furthermore, JunB undergoes phase separation in the nucleus and in vitro, mediated by its intrinsic disordered region and DNA-binding domain. Nuclear localization and condensation behaviors are required for JunB-mediated proliferation and apoptosis. Thus, our study uncovers the roles of JunB and its coacervation in repairing vascular endothelial damage caused by high glucose, elucidating the involvement of phase separation in diabetes and diabetic endothelial dysfunction.

A single-cell atlas of Drosophila trachea reveals glycosylation-mediated Notch signaling in cell fate specification

The Drosophila tracheal system is a favorable model for investigating the program of tubular morphogenesis. This system is established in the embryo by post-mitotic cells, but also undergoes remodeling by adult stem cells. Here, we provide a comprehensive cell atlas of Drosophila trachea using the single-cell RNA-sequencing (scRNA-seq) technique. The atlas documents transcriptional profiles of tracheoblasts within the Drosophila airway, delineating 9 major subtypes. Further evidence gained from in silico as well as genetic investigations highlight a set of transcription factors characterized by their capacity to switch cell fate. Notably, the transcription factors Pebbled, Blistered, Knirps, Spalt and Cut are influenced by Notch signaling and determine tracheal cell identity. Moreover, Notch signaling orchestrates transcriptional activities essential for tracheoblast differentiation and responds to protein glycosylation that is induced by high sugar diet. Therefore, our study yields a single-cell transcriptomic atlas of tracheal development and regeneration, and suggests a glycosylation-responsive Notch signaling in cell fate determination.

Promoting collateral formation in type 2 diabetes mellitus using ultra-small nanodots with autophagy activation and ROS scavenging

BACKGROUND

Impaired collateral formation is a major factor contributing to poor prognosis in type 2 diabetes mellitus (T2DM) patients with atherosclerotic cardiovascular disease. However, the current pharmacological treatments for improving collateral formation remain unsatisfactory. The induction of endothelial autophagy and the elimination of reactive oxygen species (ROS) represent potential therapeutic targets for enhancing endothelial angiogenesis and facilitating collateral formation. This study investigates the potential of molybdenum disulfide nanodots (MoS2 NDs) for enhancing collateral formation and improving prognosis.

RESULTS

Our study shows that MoS2 NDs significantly enhance collateral formation in ischemic tissues of diabetic mice, improving effective blood resupply. Additionally, MoS2 NDs boost the proliferation, migration, and tube formation of endothelial cells under high glucose/hypoxia conditions in vitro. Mechanistically, the beneficial effects of MoS2 NDs on collateral formation not only depend on their known scavenging properties of ROS (H2O2, •O2-, and •OH) but also primarily involve a molecular pathway, cAMP/PKA-NR4A2, which promotes autophagy and contributes to mitigating damage in diabetic endothelial cells.

CONCLUSIONS

Overall, this study investigated the specific mechanism by which MoS2 NDs mediated autophagy activation and highlighted the synergy between autophagy activation and antioxidation, thus suggesting that an economic and biocompatible nano-agent with dual therapeutic functions is highly preferable for promoting collateral formation in a diabetic context, thus, highlighting their therapeutic potential.

Adipose mesenchymal stem cell-derived exosomes promote skin wound healing in diabetic mice by regulating epidermal autophagy

Background

Adipose mesenchymal stem cell-derived exosomes (ADSC-Exos) have great potential in the field of tissue repair and regenerative medicine, particularly in cases of refractory diabetic wounds. Interestingly, autophagy plays a role in wound healing, and recent research has demonstrated that exosomes are closely associated with intracellular autophagy in biogenesis and molecular signaling mechanisms. Therefore, this study aimed to investigate whether ADSC-Exos promote the repair of diabetic wounds by regulating autophagy to provide a new method and theoretical basis for the treatment of diabetic wounds.

Methods

Western blot analysis and autophagy double-labelled adenovirus were used to monitor changes in autophagy flow in human immortalized keratinocyte cell line (HaCaT) cells. ADSC-Exos were generated from ADSC supernatants via ultracentrifugation. The effectiveness of ADSC-Exos on HaCaT cells was assessed using a live-cell imaging system, cell counting kit-8 and cell scratch assays. The cells were treated with the autophagy inhibitor bafilomycin A1 to evaluate the effects of autophagy on cell function. The recovery of diabetic wounds after ADSC-Exo treatment was determined by calculating the healing rates and performing histological analysis. High-throughput transcriptome sequencing was used to analyze changes in mRNA expression after the treatment of HaCaT cells with ADSC-Exos.

Results

ADSC-Exos activated autophagy in HaCaT cells, which was inhibited by high glucose levels, and potentiated their cellular functions. Moreover, ADSC-Exos in combination with the autophagy inhibitor bafilomycin A1 showed that autophagy defects further impaired the biological function of epidermal cells under high-glucose conditions and partially weakened the healing effect of ADSC-Exos. Using a diabetes wound model, we found that ADSC-Exos promoted skin wound healing in diabetic mice, as evidenced by increased epidermal autophagy and rapid re-epithelialization. Finally, sequencing results showed that increased expression of autophagy-related genes nicotinamide phosphoribosyltransferase (NAMPT), CD46, vesicle-associated membrane protein 7 (VAMP7), VAMP3 and eukaryotic translation initiation factor 2 subunit alpha (EIF2S1) may contribute to the underlying mechanism of ADSC-Exo action.

Conclusions

This study elucidated the molecular mechanism through which ADCS-Exos regulate autophagy in skin epithelial cells, thereby providing a new theoretical basis for the treatment and repair of skin epithelial damage by ADSC-Exos.

Angiogenesis-on-a-chip coupled with single-cell RNA sequencing reveals spatially differential activations of autophagy along angiogenic sprouts

Several functions of autophagy associated with proliferation, differentiation, and migration of endothelial cells have been reported. Due to lack of models recapitulating angiogenic sprouting, functional heterogeneity of autophagy in endothelial cells along angiogenic sprouts remains elusive. Here, we apply an angiogenesis-on-a-chip to reconstruct 3D sprouts with clear endpoints. We perform single-cell RNA sequencing of sprouting endothelial cells from our chip to reveal high activation of autophagy in two endothelial cell populations- proliferating endothelial cells in sprout basements and stalk-like endothelial cells near sprout endpoints- and further the reciprocal expression pattern of autophagy-related genes between stalk- and tip-like endothelial cells near sprout endpoints, implying an association of autophagy with tip-stalk cell specification. Our results suggest a model describing spatially differential roles of autophagy: quality control of proliferating endothelial cells in sprout basements for sprout elongation and tip-stalk cell specification near sprout endpoints, which may change strategies for developing autophagy-based anti-angiogenic therapeutics.

Rapamycin promotes hematoma resorption and enhances endothelial cell function by suppressing the mTOR/STAT3 signaling in chronic subdural hematoma

Chronic subdural hematoma (CSDH) remains a neurosurgical condition and a healthy burden especially in elderly patients. This study focuses on the functions of rapamycin and its related molecular mechanisms in CSDH management. A rat model of CSDH was induced, which developed significant hematoma on day 5 after operation. The rats were treated with rapamycin or atorvastatin, a drug with known effect on hematoma alleviation, or treated with rapamycin and atorvastatin in combination. The atorvastatin or rapamycin treatment reduced the hematoma development, blood-brain barrier permeability, neurological dysfunction in CSDH rats, and the combination treatment showed more pronounced effects. Human brain microvascular endothelial cells hCMEC/D3 were stimulated by hematoma samples to mimic a CSDH condition in vitro. The drug treatments elevated the cell junction-related factors and reduced the pro-inflammatory cytokines both in rat hematoma tissues and in hCMEC/D3 cells. Rapamycin suppressed the mTOR and STAT3 signaling pathways. Overexpression of mTOR or the STAT3 agonist suppressed the alleviating effects of rapamycin on CSDH. In summary, this study demonstrates that rapamycin promotes hematoma resorption and enhances endothelial cell function by suppressing the mTOR/STAT3 signaling.

Fiber-reinforced gelatin/β-cyclodextrin hydrogels loaded with platelet-rich plasma-derived exosomes for diabetic wound healing

Diabetic complications with high-glucose status (HGS) cause the dysregulated autophagy and excessive apoptosis of multiple-type cells, leading to the difficulty in wound self-healing. Herein, we firstly developed fiber-reinforced gelatin (GEL)/β-cyclodextrin (β-CD) therapeutic hydrogels by the modification of platelet-rich plasma exosomes (PRP-EXOs). The GEL fibers that were uniformly dispersed within the GEL/β-CD hydrogels remarkably enhanced the compression strengths and viscoelasticity. The PRP-EXOs were encapsulated in the hydrogels via the covalent crosslinking between the PRP-EXOs and genipin. The diabetic rat models demonstrated that the GEL/β-CD hydrogels and PRP-EXOs cooperatively promoted diabetic wound healing. On the one hand, the GEL/β-CD hydrogels provided the biocompatible microenvironments and active components for cell adhesion, proliferation and skin tissue regeneration. On the other hand, the PRP-EXOs in the therapeutic hydrogels significantly activated the autophagy and inhibited the apoptosis of human umbilical vein endothelial cells (HUVECs) and human skin fibroblasts (HSFs). The activation of autophagy and inhibition of apoptosis in HUVECs and HSFs induced the blood vessel creation, collagen formation and re-epithelialization. Taken together, this work proved that the incorporation of PRP-EXOs in a wound dressing was an effective strategy to regulate autophagy and apoptosis, and provide a novel therapeutic platform for diabetic wound healing.

Clemastine fumarate attenuates tauopathy and meliorates cognition in hTau mice via autophagy enhancement

Clemastine fumarate, which has been identified as a promising agent for remyelination and autophagy enhancement, has been shown to mitigate Aβ deposition and improve cognitive function in the APP/PS1 mouse model of Alzheimer's disease. Based on these findings, we investigated the effect of clemastine fumarate in hTau mice, a different Alzheimer's disease model characterized by overexpression of human Tau protein. Surprisingly, clemastine fumarate was effective in reducing pathological deposition of Tau protein, protecting neurons and synapses from damage, inhibiting neuroinflammation, and improving cognitive impairment in hTau mice. Interestingly, chloroquine, an autophagy inhibitor, had a significant impact on total and Sarkosyl fractions of autophagy, demonstrating that it can interrupt autophagy. Notably, after administration of chloroquine, levels of Tau protein were significantly increased. When clemastine fumarate was co-administered with chloroquine, the protective effects were reversed, indicating that clemastine fumarate indeed triggered autophagy and promoted the degradation of Tau protein, while also inhibiting further Tauopathy-related neuroinflammation and synapse loss to improve cognitive function in hTau mice.

Physiological and pathological characteristics of vascular endothelial injury in diabetes and the regulatory mechanism of autophagy

Vascular endothelial injury in diabetes mellitus (DM) is the major cause of vascular disease, which is closely related to the occurrence and development of a series of vascular complications and has a serious negative impact on a patient's health and quality of life. The primary function of normal vascular endothelium is to function as a barrier function. However, in the presence of DM, glucose and lipid metabolism disorders, insulin resistance, inflammatory reactions, oxidative stress, and other factors cause vascular endothelial injury, leading to vascular endothelial lesions from morphology to function. Recently, numerous studies have found that autophagy plays a vital role in regulating the progression of vascular endothelial injury. Therefore, this article compares the morphology and function of normal and diabetic vascular endothelium and focuses on the current regulatory mechanisms and the important role of autophagy in diabetic vascular endothelial injury caused by different signal pathways. We aim to provide some references for future research on the mechanism of vascular endothelial injury in DM, investigate autophagy's protective or injurious effect, and study potential drugs using autophagy as a target.

Autophagy-mediated circHIPK2 promotes lipopolysaccharide-induced astrocytic inflammation via SIGMAR1

Circular RNAs (circRNAs) are a subclass of noncoding RNAs and widely involve in the occurrence of multiple human diseases. It is an urgent task to clarify circRNA upstream regulation mechanism and seek their biofunction. Our previous study has confirmed that circular RNA HIPK2 (circHIPK2) promotes astrocyte activation via SIGMAR1, sigma non-opioid intracellular receptor 1, in a mouse model of single high-dose lipopolysaccharide (LPS) injection. However, what mechanism circHIPK2 is regulated by and whether it is involved in the inflammatory response of astrocytes remain unclear. In this study, we reported that circHIPK2 and SIGMAR1 were significantly increased in mouse prefrontal cortex after multiple intraperitoneal injection of LPS, with the elevation of inflammatory mediators. Knockdown circHIPK2 in primary astrocytes suppressed the SIGMAR1 expression and inflammation. Pretreatment of autophagy inducer rapamycin on astrocytes suppressed the circHIPK2 expression and inactivated inflammatory response. These results implied that autophagy inducer rapamycin could suppress astrocytic inflammation by inactivating circHIPK2-SIGMAR1 axis. Autophagy may be a promising upstream administrator of circHIPK2 and therapeutic target for central nervous system inflammation.

Type 2 diabetes mellitus induced autophagic response within pulmonary tissue in the rat model

Introduction: The current experiment aimed to address the impact of type 2 diabetes mellitus on autophagy status in the rat pulmonary tissue. Methods: In this study, 20 male Wistar rats were randomly allocated into two groups as follows: control and diabetic groups. To induce type 2 diabetes mellitus, rats received a combination of streptozotocin (STZ) and a high-fat diet. After confirmation of diabetic condition, rats were maintained for 8 weeks and euthanized for further analyses. The pathological changes were assessed using H&E staining. We also measured transforming growth factor-β (TGF-β), bronchoalveolar lavage fluid (BALF), and tumor necrosis factor-α (TNF-α) in the lungs using ELISA and real-time PCR analyses, respectively. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were monitored in diabetic lungs to assess oxidative status. We also measured the expression of becline-1, LC3, and P62 to show autophagic response under diabetic conditions. Using immunofluorescence staining, protein levels of LC3 was also monitored. Results: H&E staining showed pathological changes in diabetic rats coincided with the increase of TNF-α (~1.4-fold) and TGF-β (~1.3-fold) compared to those in the normal rats (P<0.05). The levels of MDA (5.6 ± 0.4 versus 6.4 ± 0.27 nM/mg protein) were increased while SOD (4.2 ± 0.28 versus 3.8 ± 0.13 U/mL) activity decreased in the diabetic rats (P<0.05). Real-time polymerase chain reaction (PCR) analysis showed the up-regulation of Becline-1 (~1.35-fold) and LC3 (~2-fold) and down-regulation of P62 (~0.8-fold) (P<0.05), showing incomplete autophagic flux. We noted the increase of LC3⁺ cells in diabetic condition compared to that in the control samples. Conclusion: The prolonged diabetic condition could inhibit the normal activity of autophagy flux, thereby increasing pathological outcomes.

Chloroquine Sensitizes Esophageal Carcinoma EC109 Cells to Paclitaxel by Inhibiting Autophagy

As an autophagy inhibitor, chloroquine (CQ) showed anti-tumor effect on several types of cancer and paclitaxel (PTX) is widely used in the treatment of esophageal carcinoma patients, but chemoresistance remains a major hurdle for PTX application due to the cytoprotective autophagy. Therefore, the aim of this study was to investigate whether CQ could elevate the anti-tumor effect of PTX on esophageal carcinoma cell line EC109 and explore the potential molecular mechanisms. We confirmed the suppressive effect of PTX on EC109 by MTT, scratch test, transwell and soft agar assay. And, we detected the key proteins in Akt/mTOR pathway, as well as the autophagy marker LC3 and p62 through Western Blot. In addition, GFP-LC3 plasmid was transfected into EC109 cells to monitor the autophagosome after CQ and PTX treatment. Ultimately, we observed the alterations in the proliferation and colony formation abilities of EC109 after knocking down mTOR by shRNA. We confirmed PTX could suppress the proliferation, migration and colony formation (all P < 0.05) abilities of EC109, and CQ could sensitize the inhibition effect of PTX by inhibiting autophagy through Akt/mTOR pathway. Furthermore, inhibiting Akt/mTOR pathway initiated autophagy and enhanced the sensitivity of EC109 to CQ and PTX. In summary, we suggest CQ could be used as a potential chemosensitizer for PTX in esophageal carcinoma treatment.

Dual effect of the herbal matcha green tea (Camellia sinensis L. kuntze) supplement in EA.hy926 endothelial cells and Artemia salina

ETHNOPHARMACOLOGICAL RELEVANCE

Matcha green tea (Camellia sinensis) based-supplements have been widely used since they present a greater content of phenolic compounds than traditional green tea, which is popularly used in the treatment of diabetes. However, there are few studies on the effectiveness and safety of matcha supplements.

AIM OF THE STUDY

This work aimed to evaluate the efficacy and safety of this supplement in endothelial cells (EA.hy926) in the hyperglycemic model and in vivo Artemia salina.

MATERIALS AND METHODS

To assess the effect of Matcha herbal supplement (MHS), EA. hy926 endothelial cells were treated with 20 μg/mL of MHS for 24 h, in a hyperglycemic medium with 35 mM glucose. After treatment, cells were trypsinized and centrifuged at 4 °C and 47×g for 5 min. The pellet was used to determine the reaction products to thiobarbituric acid and the levels of nitric oxide. Electron transport chain activity and ATP levels were also evaluated. Intracellular pH, apoptosis, and mitochondrial membrane depolarization were evaluated by flow cytometry. MHS chemical characterization was performed by HPLC-UV and total phenolic content analysis. The evaluation of the antioxidant capacity of MHS was performed by 2,2-diphenyl-1-picrylhydrazyl radical scavenger assay. To determine the in vivo acute toxicity of MHS, an A. salina assay was conducted, using 0,2 mL of different concentrations of MHS (10, 50, 100, 250, 500, 750 and 1000 μg/mL). The LD₅₀ values were obtained by interpolation of 50% (y = 50) of the dead individuals in the trend curves.

RESULTS

Our data showed that MHS was able to avoid oxidative and nitrosative stress induced by hyperglycemia, demonstrating important antioxidant activity. However, it was observed that MHS reduced up to 90% the activity of the four-electron transport complexes, reducing the ATP production of the endothelial cells. In the toxicity assay performed in Artemia salina, MHS showed mild toxicity (LD₅₀ = 0,4 mg/mL). The major compounds found in MHS were epigallocatechin gallate, epicatechin, rutin, kaempferol, and quercetin.

CONCLUSIONS

This data draws attention to the fact that supplements with high content of phenolic compounds, capable of avoiding oxidative and nitrosative stress can have a dual effect and, simultaneously to antioxidant activity, can induce toxicity in different cell types.

Beclin1- and Atg13-dependent autophagy activation and morroniside have synergistic effect on osteoblastogenesis

Morroniside is known to improve osteoporosis by promoting osteoblastogenesis. The activation of PI3K/Akt/mTOR signaling is a significant mechanism in morroniside-promoted osteoblastogenesis. It is well known that protective autophagy is an important factor in osteoblastogenesis. However, the activation of mTOR signaling can inhibit autophagy. This study aimed to investigate the relationship between mTOR signaling and autophagy in morroniside-regulated osteoblastogenesis. In this study, we investigated the effect of morroniside on the autophagic activity (LC3 conversion rate, LC3-puncta formation, and autophagosome number) of differentiated osteoblast precursors (MC3T3-E1 cells). Then, we identified the roles of mTOR knockdown in morroniside-regulated alterations of autophagy and osteogenic parameters in MC3T3-E1 cells. Next, mTOR knockdown and overexpression were used to observe the roles of mTOR in morroniside-regulated alterations of autophagic molecules (Atg7, Atg13, and Beclin1). Subsequently, the additional value of the above autophagic molecules on morroniside-regulated osteogenic parameters in MC3T3-E1 cells was analyzed based on lentiviral transduction. Finally, combined with morroniside and TAT-Beclin1, the roles of Beclin1 upregulation in the in vivo effects of morroniside was investigated. Our experimental data showed that morroniside promoted both the mTOR activity and autophagy in MC3T3-E1 cells. Morroniside-upregulated autophagic activity and Atg13 or Beclin1 protein level in MC3T3-E1 cells were enhanced by mTOR knockdown. Furthermore, Morroniside-upregulated Atg13 and Beclin1 expression was reversed by mTOR overexpression. Importantly, autophagy upregulation with overexpression of the autophagic gene, Atg13 or BECN1 (gene form of Beclin1), significantly promoted osteoblastogenesis regulated by morroniside. The promotional effect of morroniside on bone microarchitecture, bone mass, and bone parameters (including trabecular bone area and OCN expression in trabecular bone) in ovariectomized (OVX) mice was enhanced by TAT-Beclin1 administration. In conclusion, the autophagy-enhancing drugs related to Beclin1 or Atg13 may be an effective adjuvant therapy in the treatment of osteoporosis with morroniside.

Catalpol Enhances Random-Pattern Skin Flap Survival by Activating SIRT1-Mediated Enhancement of Autophagy

Random-pattern skin flap necrosis limits its application in the clinic. It is still a challenge for plastic surgeons. Catalpol is an effective ingredient extracted from Rehmannia glutinosa, which is reported to promote angiogenesis and protect against ischemic cerebral disease. The aim of our experiment is to assess whether catalpol can facilitate random flap survival and the underlying mechanisms. Male “McFarlane flap” rat models were employed to explore the protective effects of catalpol. The range of necrosis in the flap was calculated 7 days after the models were established. The flap specimens were harvested for further experiments, including angiogenesis, apoptosis, oxidative stress, and autophagy evaluation. Catalpol-treated group promoted the average survival area of the flap than that in the control group. Based on immunohistochemical staining, Western blotting, and ROS detection, we found that catalpol significantly reduces oxidative stress and apoptosis and increases angiogenesis. Hematoxylin and eosin (H&E) staining and laser Doppler images further clarified the enhancement of angiogenesis after catalpol treatment. The impact of catalpol in flap was switched by using 3-methyladenine (3MA), proving the important role of autophagy in curative effect of catalpol on skin flaps. Importantly, the ability of catalpol to regulate autophagy is mediated by the activation of sirtuin 1 (SIRT1) based on its high affinity for SIRT1. Our findings revealed that catalpol improved the viability of random skin flaps by activating SIRT1-mediated autophagy pathway.

Putative therapeutic impacts of cardiac CTRP9 in ischaemia/reperfusion injury

Recently, cytokines belonging to C1q/tumour necrosis factor‐related proteins (CTRPs) superfamily have attracted increasing attention due to multiple metabolic functions and desirable anti‐inflammatory effects. These various molecular effectors exhibit key roles upon the onset of cardiovascular diseases, making them novel adipo/cardiokines. This review article aimed to highlight recent findings correlated with therapeutic effects and additional mechanisms specific to the CTRP9, particularly in cardiac ischaemia/reperfusion injury (IRI). Besides, the network of the CTPR9 signalling pathway and its possible relationship with IRI were discussed. Together, the discovery of all involved underlying mechanisms could shed light to alleviate the pathological sequelae after the occurrence of IRI.

Autophagy and skin wound healing

Autophagy is a lysosome-dependent, self-renewal mechanism that can degrade and recycle cellular components in eukaryotic cells to maintain the stability of the intracellular environment and the cells ability to cope with unfavorable environments. Numerous studies suggest that autophagy participates in regulating various cellular functions and is closely associated with the onset and progression of various diseases. Wound healing is a complex, multistep biological process that involves multiple cell types. Refractory wounds, which include diabetic skin ulcers, can seriously endanger human health. Previous studies have confirmed that autophagy plays an essential role in various phases of wound healing. Specifically, in the inflammatory phase, autophagy has an anti-infection effect and it negatively regulates the inflammatory response, which prevents excessive inflammation from causing tissue damage. In the proliferative phase, local hypoxia in the wound can induce autophagy, which plays a role in anti-apoptosis and anti-oxidative stress and promotes cell survival. Autophagy of vascular endothelial cells promotes wound angiogenesis and that of keratinocytes promotes their differentiation, proliferation and migration, which is conducive to the completion of wound re-epithelialisation. In the remodeling phase, autophagy of fibroblasts affects the formation of hypertrophic scars. Additionally, a refractory diabetic wound may be associated with increased levels of autophagy, and the regulation of mesenchymal stem cell autophagy may improve its application to wound healing. Therefore, understanding the relationship between autophagy and skin wound healing and exploring the molecular mechanism of autophagy regulation may provide novel strategies for the clinical treatment of wound healing.

p62 works as a hub modulation in the ageing process

p62 (also known as SQSTM1) is widely used as a predictor of autophagic flux, a process that allows the degradation of harmful and unnecessary components through lysosomes to maintain protein homeostasis in cells. p62 is also a stress-induced scaffold protein that resists oxidative stress. The multiple domains in its structure allow it to be connected with a variety of vital signalling pathways, autophagy and the ubiquitin proteasome system (UPS), allowing p62 to play important roles in cell proliferation, apoptosis and survival. Recent studies have shown that p62 is also directly or indirectly involved in the ageing process. In this review, we summarize in detail the process by which p62 regulates ageing from multiple ageing-related signs with the aim of providing new insight for the study of p62 in ageing.

Rapamycin Suppresses Penile NADPH Oxidase Activity to Preserve Erectile Function in Mice Fed a Western Diet

The mechanistic target of rapamycin (mTOR) is a nutrient-sensitive cellular signaling kinase that has been implicated in the excess production of reactive oxygen species (ROS). NADPH oxidase-derived ROS have been implicated in erectile dysfunction pathogenesis. The objective of this study was to determine if mTOR is an activator of NADPH oxidase in the penis and to determine the functional relevance of this pathway in a translationally relevant model of diet-induced erectile dysfunction. Male mice were fed a control diet or a high-fat, high-sucrose Western style diet (WD) for 12 weeks and treated with vehicle or rapamycin for the final 4 weeks of the dietary intervention. Following the intervention, erectile function was assessed by cavernous nerve-stimulated intracavernous pressure measurement, in vivo ROS production was measured in the penis using a microdialysis approach, and relative protein contents from the corpus cavernosum were determined by Western blot. Erectile function was impaired in vehicle treated WD-mice and was preserved in rapamycin treated WD-mice. Penile NADPH oxidase-mediated ROS were elevated in WD-mice and suppressed by rapamycin treatment. Western blot analysis suggests mTOR activation with WD by increased active site phosphorylation of mTOR and p70S6K, and increased expression of NADPH oxidase subunits, all of which were suppressed by rapamycin. These data suggest that mTOR is an upstream mediator of NADPH oxidase in the corpus cavernosum in response to a chronic Western diet, which has an adverse effect on erectile function.

Melatonin and prolonged physical activity attenuated the detrimental effects of diabetic condition on murine cardiac tissue

In this study, the combined effects of four-week swimming training and melatonin were examined on the oxidative response, inflammation, apoptosis, and angiogenesis capacity of cardiac tissue in the mouse model of diabetes. The mice were randomly allocated into five groups (n = 10 per group) as follows: Control; Diabetic group; Diabetic + Melatonin group; Diabetic + Exercise group; and Diabetic + Exercise + Melatonin group. 50 mg/kg streptozotocin was intraperitoneally administrated. In melatonin-treated groups, melatonin was injected intraperitoneally at 3 mg/kg body weight for four weeks and twice weekly. Swimming exercises were performed for four weeks. We measured cardiac superoxide dismutase, glutathione peroxidase enzymes, malondialdehyde, and total antioxidant capacity. The expression of tumor necrosis factor-α, Caspase‑3, Sirtuin1, and Connexin-43 was measured using real-time PCR analysis. The vascular density was analyzed by immunohistochemistry using CD31 and α-smooth muscle actin antibodies. The combination of melatonin and exercise elevated cardiac superoxide dismutase, glutathione peroxidase coincided with the reduction of malondialdehyde and increase of total antioxidant capacity as compared to the diabetic mice (p < 0.05). In Diabetic + Exercise + Melatonin mice, tumor necrosis factor-α, Caspase‑3 was significantly down-regulated compared to the Diabetic group (p < 0.05). Melatonin and exercise suppressed the expression of Connexin-43 and Sirtuin1 in diabetic mice in comparison with the control mice (p < 0.05). H & E staining showed necrosis and focal hyperemia reduction in the Diabetic + Exercise + Melatonin group compared to the Diabetic group. Data showed a decrease of CD31+ and α-smooth muscle actin+ vessels in the Diabetic group as compared to the normal samples (p < 0.05). The number of CD31+ vessels, but not α-smooth muscle actin+ type, increased in the Diabetic + Exercise + Melatonin group compared to the Diabetic mice. These data demonstrated that exercise along with melatonin administration could diminish the detrimental effects of diabetes on cardiac tissue via using different mechanisms.

Autophagy attenuates high glucose-induced oxidative injury to lens epithelial cells

Purpose: Autophagic dysfunction and abnormal oxidative stress are associated with cataract. The purpose of the present study was to investigate the changes of cellular autophagy and oxidative stress and their association in lens epithelial cells (LECs) upon exposure to high glucose.

Methods: Autophagy and oxidative stress-related changes were detected in streptozotocin-induced Type 1 diabetic mice and normal mouse LECs incubated in high glucose conditions. Rapamycin at a concentration of 100 nm/l or 50 μM chloroquine was combined for analysis of the relationship between autophagy and oxidative stress. The morphology of LECs during autophagy was observed by transmission electron microscopy. The expressions of autophagy markers (LC3B and p62) were identified, as well as the key factors of oxidative stress (SOD2 and CAT) and mitochondrial reactive oxygen species (ROS) generation.

Results: Transmission electron microscopy indicated an altered autophagy activity in diabetic mouse lens tissues with larger autophagosomes and multiple mitochondria. Regarding the expressions, LC3B was elevated, p62 was decreased first and then increased, and SOD2 and CAT were increased before a decrease during 4 months of follow-up in diabetic mice and 72 h of culture under high glucose for mouse LECs. Furthermore, rapamycin promoted the expressions of autophagy markers but alleviated those of oxidative stress markers, whereas chloroquine antagonized autophagy but enhanced oxidative stress by elevating ROS generation in LECs exposed to high glucose.

Conclusions: The changes in autophagy and oxidative stress were fluctuating in the mouse LECs under constant high glucose conditions. Autophagy might attenuate high glucose-induced oxidative injury to LECs.

Oxidative Stress Triggers Defective Autophagy in Endothelial Cells: Role in Atherothrombosis Development

Atherothrombosis, a multifactorial and multistep artery disorder, represents one of the main causes of morbidity and mortality worldwide. The development and progression of atherothrombosis is closely associated with age, gender and a complex relationship between unhealthy lifestyle habits and several genetic risk factors. The imbalance between oxidative stress and antioxidant defenses is the main biological event leading to the development of a pro-oxidant phenotype, triggering cellular and molecular mechanisms associated with the atherothrombotic process. The pathogenesis of atherosclerosis and its late thrombotic complications involve multiple cellular events such as inflammation, endothelial dysfunction, proliferation of vascular smooth muscle cells (SMCs), extracellular matrix (ECM) alterations, and platelet activation, contributing to chronic pathological remodeling of the vascular wall, atheromatous plague formation, vascular stenosis, and eventually, thrombus growth and propagation. Emerging studies suggest that clotting activation and endothelial cell (EC) dysfunction play key roles in the pathogenesis of atherothrombosis. Furthermore, a growing body of evidence indicates that defective autophagy is closely linked to the overproduction of reactive oxygen species (ROS) which, in turn, are involved in the development and progression of atherosclerotic disease. This topic represents a large field of study aimed at identifying new potential therapeutic targets. In this review, we focus on the major role played by the autophagic pathway induced by oxidative stress in the modulation of EC dysfunction as a background to understand its potential role in the development of atherothrombosis.

Ambient particulate matter-associated autophagy alleviates pulmonary inflammation induced by Platanus pollen protein 3 (Pla3)

Subpollen particles (SPPs) with diameter less than 1 mm released from allergenic pollen grains contain allergens could trigger asthma and lung inflammation after being inhaled. In the meaning time, ambient fine particles attached on the pollen grains could have further effects on the inflammation. However, the mechanisms underlying these phenomena have not been fully elucidated. In this study, the effects of autophagy triggered by PM_2.5 and Platanus SPPs were evaluated by using the A549 cell lines and a pollen sensitized rat model. First, autophagy in A549 cells was analyzed after exposure to PM_2.5 using acridine orange staining, real-time quantitative PCR (qRT-PCR), and western blot (WB) assays. The increased levels of ROS, superoxide dismutase, and malonaldehyde in the lung homogenates of rats exposed to SPPs indicated that inflammatory response was triggered in the lungs. Treatment with autophagy-inhibiting drugs showed that autophagy suppressed ROS formation and decreased the production of thymic stromal lymphopoietin (TSLP), a critical pathway altering the inflammatory response. Although the effect was indirect, autophagy appeared to negatively regulate TSLP levels, resulting in a compromised immune response. These results suggested that SPPs promote ROS generation and increase TSLP levels, triggering downstream inflammation reactions. However, ambient PM_2.5 could aggravate autophagy, which in turn effectively suppressed ROS and TSLP levels, leading to the alleviation of the immune response and pulmonary inflammation.

Porcine placenta extract improves high-glucose-induced angiogenesis impairment

Background

High glucose (HG)-induced reactive oxygen species (ROS) overproduction impairs angiogenesis that is one pivotal factor of wound healing process. Angiogenesis impairment induces delayed wound healing, whereby it eventually leads to amputation in cases of poorly controlled diabetes with diabetic ulceration. Porcine placenta extract (PPE) is a natural waste product that comprises plenty of bioactive agents including growth factors and antioxidants. It was reported as an effective compound that prevents ROS generation. The goal of this study was to investigate the in vitro effect of PPE on HG-induced ROS-mediated angiogenesis impairment.

Methods

Primary endothelial cells (HUVECs) and endothelial cell line (EA.hy926) were treated with HG in the presence of PPE. The endothelial cells (ECs) viability, intracellular ROS generation, migration, and angiogenesis were determined by MTT assay, DCFDA reagent, wound healing assay, and tube formation assay, respectively. Additionally, the molecular mechanism of PPE on HG-induced angiogenesis impairment was investigated by Western blot. The angiogenic growth factor secretion was also investigated by the sandwich ELISA technique.

Results

HG in the presence of PPE significantly decreased intracellular ROS overproduction compared to HG alone. HG in the presence of PPE significantly increased ECs viability, migration, and angiogenesis compared to HG alone by showing recovery of PI3K/Akt/ERK1/2 activation. HG in the presence of PPE also decreased ECs apoptosis compared to HG alone by decreasing p53/Bax/cleaved caspase 9/cleaved caspase 3 levels and increasing Bcl 2 level.

Conclusion

PPE attenuated HG-induced intracellular ROS overproduction that improved ECs viability, proliferation, migration, and angiogenesis by showing recovery of PI3K/Akt/ERK1/2 activation and inhibition of ECs apoptosis. This study suggests PPE ameliorated HG-induced ROS-mediated angiogenesis impairment, whereby it potentially provides an alternative treatment for diabetic wounds.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03243-z.

Plasma from obese children increases monocyte-endothelial adhesion and affects intracellular insulin signaling in cultured endothelial cells: Potential role of mTORC1-S6K1

Childhood obesity is characterized by the loss of vascular insulin sensitivity along with altered oxidant-antioxidant state and chronic inflammation, which play a key role in the onset of endothelial dysfunction. We previously demonstrated a reduced insulin-stimulated Nitric Oxide (NO) bioavailability in Human Umbilical Vein Endothelial cells (HUVECs) cultured with plasma from obese pre-pubertal children (OB) compared to those cultured with plasma of normal-weight children (CTRL). However, mechanisms underlying endothelial dysfunction in childhood obesity remains poorly understood. Hence, the present study aimed to better investigate these mechanisms, also considering a potential involvement of mammalian Target Of Rapamycin Complex1 (mTORC1)-ribosomal protein S6 Kinase beta1 (S6K1) pathway. OB-children (N = 32, age: 9.2 ± 1.7; BMI z-score: 2.72 ± 0.31) had higher fasting insulin levels and increased HOMA-IR than CTRL-children (N = 32, age: 8.8 ± 1.2; BMI z-score: 0.33 ± 0.75). In vitro, HUVECs exposed to OB-plasma exhibited significant increase in Reactive Oxygen Species (ROS) levels, higher vascular and intercellular adhesion molecules exposure, together with increased monocytes-endothelial interaction. This was associated with unbalanced pro- and anti-atherogenic endothelial insulin stimulated signaling pathways, as measured by increased Mitogen Activated Protein Kinase (MAPK) and decreased Insulin Receptor Substrate-1 (IRS-1)/protein kinase B (Akt)/ endothelial NO Synthase (eNOS) phosphorylation levels, together with augmented S6K1 activation. Interestingly, inhibition of mTORC1-S6K1 pathway using rapamycin significantly restored the IRS-1/Akt/eNOS activation, suggesting a feedback regulation of IRS-1/Akt signal through S6K1. Overall, our in vitro data shed light on new mechanisms underlying the onset of endothelial dysfunction in childhood obesity.

ET-1 regulates the human umbilical vein endothelial cell cycle by adjusting the ERβ/FOXN1 signaling pathway

Background

Atherosclerosis (AS) is a chronic and progressive disease primarily induced by inflammation of the arterial blood vessel wall. Investigating the function and molecular regulation mechanisms of ET-1, ERβ, and FOXN1 in disease models will provide new targets and means for clinical treatment.

Methods

The effects of ET-1 on oxidative stress in HUVEC were verified through quantitative polymerase chain reaction (qPCR), western blot, flow cytometry, as well as dual luciferase reporter gene and biochemical assays.

Results

Compared with the ET-1+ negative control (NC) group, the ERβ messenger ribonucleic acid (mRNA) expression level was significantly reduced, and the FOXN1 mRNA expression level increased markedly in the ET-1 + ERβ small interfering ribonucleic acid (siRNA) group. Meanwhile, the FOXN1 mRNA expression level was significantly reduced in the ET-1 + FOXN1 siRNA group. FOXN1 promoter luciferase reporter gene activity was notably enhanced in the ERβ siRNA group compared with the siRNA control group. Compared with the ET-1 + NC group, the levels of reaction oxygen species (ROS) in the ET-1 + ERβ siRNA group increased considerably, the superoxide dismutase (SOD) level was significantly reduced, and the G0/G1 phase cell ratio was reduced. In addition, the protein expression of ERβ and cyclin B1 (CCNB1) was markedly reduced, whereas the protein expression of cyclin A2 (CCNA2), cyclin D1 (CCND1), and cyclin E1 (CCNE1) increased substantially. The opposite result was observed in the ET-1 + FOXN1 siRNA group.

Conclusions

ET-1 can contribute to the expression of ERβ and FOXN1. ERβ can inhibit the expression of FOXN1 by regulating promoter activity. The ET-1/ERβ/FOXN1 signaling pathway is involved in the regulation of oxidative stress and cycle progression in HUVEC. This study provides a new mechanism for the regulation of umbilical vein endothelial cells. The ET-1/ERβ/FOXN1 signaling pathway may provide novel therapeutic targets and strategies for the treatment of atherosclerosis.

Human retinal pigment epithelial cells are protected against hypoxia by BNIP3

Background

Hypoxia has been implicated in the process of retinal pigment epithelium (RPE) dysfunction. However, recent studies suggest that hypoxia contributes to survival rather than cell death through induction of Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3)-dependent autophagy. In contrast, persistent oxidative stress was found to result in autophagy dysregulation in RPE cells. These seemingly contradictory findings led us to investigate the potential role of BNIP3, a crucial mediator of hypoxia-induced autophagy, in the context of hypoxic RPE cells.

Methods

Human RPE D407 cells were treated with low-oxygen conditions, and cell growth, apoptosis, and autophagy was assessed by Cell Counting Kit-8 assay, flow cytometry analysis and immunofluorescence staining, respectively.

Results

Hypoxic conditions simultaneously triggered a large amount of apoptosis and inhibited autophagy. Moreover, hypoxia led to severe impairments, including the stimulation of reactive oxygen species, and reduction of mitochondrial membrane potential, and adenosine triphosphate production. The stimulation of autophagy by rapamycin inhibited hypoxia-induced severe impairments to a great extent. Interestingly, similar results were observed for BNIP3 overexpression, which can be largely blocked by 3-MA, a well-defined inhibitor of autophagy. Moreover, BNIP3 knockdown further aggravated hypoxia-induced impairments in D407 cells, which can be reversed by rapamycin.

Conclusions

Collectively, these results indicated that BNIP3 can protect human retinal pigmented epithelial cells under hypoxic conditions by inducing autophagy.

Small extracellular vesicles secreted by human iPSC-derived MSC enhance angiogenesis through inhibiting STAT3-dependent autophagy in ischemic stroke

Background

Small extracellular vesicles (sEV) secreted by mesenchymal stem cells (MSC) derived from human induced pluripotent stem cells (iPSC, iMSC-sEV) are considered to have great potential in treating ischemic diseases. Angiogenesis play an important role in post-stroke recovery. However, no studies have yet been conducted to systemically examine the effect and the underlying mechanism of iMSC-sEV on angiogenesis under brain ischemia conditions.

Methods

Ischemic stroke model was performed in rats induced by middle cerebral artery occlusion (MCAO), and the pro-angiogenic capacity of iMSC-sEV was measured. The in vitro effects of iMSC-sEV on the migration and tube formation of endothelial cells were investigated, respectively. Autophagy and autophagy-related signaling pathway were detected in vivo and in vitro.

Results

We found that iMSC-sEV significantly reduced infarct volume, enhanced angiogenesis, and alleviated long-term neurological deficits in rats after stroke. We also demonstrated that iMSC-sEV increased migration and tube formation of endothelial cells in vitro. A further mechanism study revealed that the pro-angiogenic effect of iMSC-sEV was correlated with a reduction in autophagy. Furthermore, iMSC-sEV significantly activated signal transducer and activator of transcription 3 (STAT3), and suppression of STAT3 abolished iMSC-sEV-induced inhibition of autophagy and promotion of angiogenesis in vivo and in vitro.

Conclusions

Taken together, our data indicate that iMSC-sEV promote angiogenesis after ischemic stroke, potentially, by inhibiting autophagy, a process that is partially dependent on STAT3 activation.

CD73+ extracellular vesicles inhibit angiogenesis through adenosine A2B receptor signalling

Pathological angiogenesis is a hallmark of several conditions including eye diseases, inflammatory diseases, and cancer. Stromal cells play a crucial role in regulating angiogenesis through the release of soluble factors or direct contact with endothelial cells. Here, we analysed the properties of the extracellular vesicles (EVs) released by bone marrow mesenchymal stromal cells (MSCs) and explored the possibility of using them to therapeutically target angiogenesis. We demonstrated that in response to pro-inflammatory cytokines, MSCs produce EVs that are enriched in TIMP-1, CD39 and CD73 and inhibit angiogenesis targeting both extracellular matrix remodelling and endothelial cell migration. We identified a novel anti-angiogenic mechanism based on adenosine production, triggering of A2B adenosine receptors, and induction of NOX2-dependent oxidative stress within endothelial cells. Finally, in pilot experiments, we exploited the anti-angiogenic EVs to inhibit tumour progression in vivo. Our results identify novel pathways involved in the crosstalk between endothelial and stromal cell and suggest new therapeutic strategies to target pathological angiogenesis.

Autophagy modulation altered differentiation capacity of CD146+ cells toward endothelial cells, pericytes, and cardiomyocytes

Background

To date, many attempts are employed to increase the regenerative potential of stem cells. In this study, we evaluated the hypothesis of whether an autophagy modulation could alter differentiation potency of CD146⁺ cells into mature pericyte, endothelial, and cardiomyocyte lineage.

Methods

In this study, CD146⁺cells were enriched from the human bone marrow aspirates and trans-differentiated into mature endothelial cells, pericytes, and cardiomyocytes after exposure to autophagy stimulator (50-μM Met)/inhibitor (15-μM HCQ). The protein levels of autophagy proteins were monitored by western blotting. NO content was measured using the Griess assay. Using real-time PCR assay and western blotting, we monitored the lineage protein and gene levels. Pro-inflammatory cytokine and angiocrine factors were measured by ELISA. The fatty acid change was determined by gas chromatography. We also measured exosome secretion capacity by measuring AChE activity and real-time PCR assay.

Result

Data revealed the modulation of autophagy factors, Beclin-1, P62, and LC3 II/I ratio in differentiating CD146⁺ cells after exposure to Met and HCQ (p < 0.05). The inhibition of autophagy increased NO content compared to the Met-treated cells (p < 0.05). Real-time PCR analysis showed that the treatment of CD146⁺ cells with autophagy modulators altered the expression of VE-cadherin, cTnI, and α-SMA (p < 0.05). Met increased the expression of VE-cadherin, α-SMA, and cTnI compared to the HCQ-treated cells (p < 0.05) while western blotting revealed the protein synthesis of all lineage-specific proteins under the stimulation and inhibition of autophagy. None statistically significant differences were found in the levels of Tie-1, Tie-2, VEGFR-1, and VEGFR-2 after autophagy modulation. Fatty acid profile analysis revealed the increase of unsaturated fatty acids after exposure to HCQ (p < 0.05). The treatment of cells with HCQ increased the levels of TNF-α and IL-6 compared to the Met-treated cells. Data revealed the increase of exosome biogenesis and secretion to the supernatant in cells treated with HCQ compared to the Met groups (p < 0.05).

Conclusions

In summary, autophagy modulation could alter differentiation potency of CD146⁺cells which is important in cardiac regeneration.

The protective effect of EGF-activated ROS in human corneal epithelial cells by inducing mitochondrial autophagy via activation TRPM2

Oxidative stress is a major pathogenesis of some ocular surface diseases. Our previous study demonstrated that epidermal growth factor (EGF)-activated reactive oxygen species (ROS) could protect against human corneal epithelial cell (HCE) injury. In the present study, we aimed to explore the role and mechanisms of oxidative stress and mitochondrial autophagy in HCE cells subjected to scratch injury. CCK-8 assays, EdU assays, Western blot analysis, wound-healing assays, and flow cytometry were conducted to determine cell viability, proliferation, protein expression, cell apoptosis, and intracellular ROS levels, respectively. The results showed that EGF could promote damage repair and inhibit cell apoptosis in scratch injured HCE cells by upregulating ROS (**p < .01, ***p < .001). EGF also induced mitochondrial autophagy and alleviated mitochondrial damage. Interestingly, the combination of the mitochondrial autophagy inhibitor and mitochondrial division inhibitor 1 (MDIVI-1) with EGF could reduce cell proliferation, viability, and the ROS level (*p < .05, **p < .01, ***p < .001). Treatment using the ROS inhibitor N-acetyl- l-cysteine abrogated the increase in mitochondrial membrane potential after EGF treatment. (*p < .05). Taken together, these findings indicated that EGF plays an important role in HCE damage repair and could activate ROS to protect against HCE injury by inducing mitochondrial autophagy via activation of TRPM2.

Hydrogen Sulfide Protects Against High Glucose-Induced Human Umbilical Vein Endothelial Cell Injury Through Activating PI3K/Akt/eNOS Pathway

Purpose

Dysfunction of endothelial cells plays a key role in the pathogenesis of diabetic atherosclerosis. High glucose (HG) has been found as a key factor in the progression of diabetic complications, including atherosclerosis. PI3K/Akt/eNOS signaling pathway has been shown to involve in HG-induced vascular injuries. Hydrogen sulfide (H₂S) has been found to exhibit protective effects on HG-induced vascular injuries. Moreover, H₂S activates PI3K/Akt/eNOS pathway in endothelial cells. Thus, the present study aimed to determine if H₂S exerts protective effects against HG-induced injuries of human umbilical vein endothelial cells (HUVECs) via activating PI3K/Akt/eNOS signaling.

Materials and Methods

The endothelial protective effects of H₂S were evaluated and compared to the controlled groups. Cell viability, cell migration and tube formation were determined by in vitro functional assays; protein levels were evaluated by Western blot assay and ELISA; cell apoptosis was determined by Hoechst 33258 nuclear staining; Reactive oxygen species (ROS) production was evaluated by the ROS detection kit.

Results

HG treatment significantly inhibited PI3K/Akt/eNOS signaling in HUVECs, which was partially reversed by the H2S treatment. HG treatment inhibited cell viability of HUVECs, which were markedly prevented by H₂S or PI3K agonist Y-P 740. HG treatment also induced HUVEC cell apoptosis by increasing the protein levels of cleaved caspase 3, Bax and Bcl-2, which were significantly attenuated by H₂S or 740 Y-P. ROS production and gp91^phox protein level were increased by HG treatment in HUVECs and this effect can be blocked by the treatment with H₂S or Y-P 740. Moreover, HG treatment increased the protein levels of pro-inflammatory cytokines, caspase-1 and phosphorylated JNK, which was significantly attenuated by H₂S or Y-P 740. Importantly, the cytoprotective effect of H₂S against HG-induced injury was inhibited by LY294002 (an inhibitor of PI3K/Akt/eNOS signaling pathway).

Conclusion

The present study demonstrated that exogenous H₂S protects endothelial cells against HG-induced injuries by activating PI3K/Akt/eNOS pathway. Based on the above findings, we proposed that reduced endogenous H₂S levels and the subsequent PI3K/Akt/eNOS signaling impairment may be the important pathophysiological mechanism underlying hyperglycemia-induced vascular injuries.

Evaluation of ameliorative effect of sodium nitrate in experimental model of streptozotocin-induced diabetic neuropathy in male rats

OBJECTIVE

Diabetes induces sensory symptoms of neuropathy as positive (hyperalgesia), negative (hypoalgesia), or both.

METHODS

In the present study, fifty male Wistar rats were allocated to five groups: control, control+nitrate, diabetes, diabetes+insulin, and diabetes+nitrate. Thirty days after diabetes confirmation, insulin (2-4 U/day) was injected subcutaneously in diabetes+insulin group and nitrate (100 mg/l) was added into drinking water of the control+nitrate and diabetes+nitrate groups for a period of 2 months. In order to assess the mechanical and thermal algesia, tail immersion, hot plate, and von Frey tests were performed. The serum insulin levels were determined with insulin ELISA Kit. Serum level of NOx was determined by the Griess method.

RESULTS

Both thermal and mechanical nociceptive thresholds showed a significant decrease (p<0.05) which was followed by a significant increase (p<0.01) in the thermal nociceptive threshold in the diabetes group. Chronic nitrate or insulin treatment led to a significant decrease (p<0.01) in blood glucose levels, as well as a significant (p<0.05) increase in the body weight and serum NOx. Moreover, nitrate treatment significantly increased serum insulin levels (p<0.001) compared to the other groups.

CONCLUSION

Chronic nitrate treatment modified the thermal and mechanical sensitivities in diabetic animals.

PSORI-CM02 ameliorates psoriasis in vivo and in vitro by inducing autophagy via inhibition of the PI3K/Akt/mTOR pathway

BACKGROUND

Psoriasis is an inflammatory skin disease that affects an estimated 3% of the world's population. PSORI-CM02 is an empirically developed Chinese medicine formula optimised from Yin Xie Ling, summarised by national medical master Guo-Wei Xuan, that has been used for decades to treat psoriasis in the Guangdong Provincial Hospital of Chinese Medicine. However, its anti-psoriatic mechanisms are still poorly understood. In this study, we explored the effects of PSORI-CM02 on autophagy and the underlying mechanisms in TNF-α-stimulated HaCaT cells and in a mouse model of imiquimod-induced psoriasis.

METHODS

Cell viability was assessed by MTT assay. Apoptosis was detected by annexin V-FITC/PI double-staining and caspase-3 assays. Autophagy was detected by electron microscopy, RT-PCR and western blotting. The PI3K/Akt/mTOR pathway was analysed by western blotting and immunochemical analysis.

RESULTS

PSORI-CM02 induced autophagy and thus inhibited the proliferation of HaCaT cells via suppression of the PI3K/Akt/mTOR pathway. In mice with IMQ-induced psoriasis, PSORI-CM02 relieved psoriasis symptoms, induced autophagy and inhibited the phosphorylation of the PI3K/AKT/mTOR pathway in the skin.

CONCLUSION

These results suggest that PSORI-CM02 treats psoriasis by inducing autophagy via inhibition of the PI3K/Akt/mTOR pathway.

VEGF-A promotes angiogenesis after acute myocardial infarction through increasing ROS production and enhancing ER stress-mediated autophagy

Proangiogenesis is generally regarded as an effective approach for treating ischemic heart disease. Vascular endothelial growth factor (VEGF)-A is a strong and essential proangiogenic factor. Reactive oxygen species (ROS), endoplasmic reticulum (ER) stress, and autophagy are implicated in the process of angiogenesis. This study is designed to clarify the regulatory mechanisms underlying VEGF-A, ROS, ER stress, autophagy, and angiogenesis in acute myocardial infarction (AMI). A mouse model of AMI was successfully established by occluding the left anterior descending coronary artery. Compared with the sham-operated mice, the microvessel density, VEGF-A content, ROS production, expression of vascular endothelial cadherin, positive expression of 78 kDa glucose-regulated protein/binding immunoglobulin protein (GRP78/Bip), and LC3 puncta in CD31-positive endothelial cells of the ischemic myocardium were overtly elevated. Moreover, VEGF-A exposure predominantly increased the expression of beclin-1, autophagy-related gene (ATG) 4, ATG5, inositol-requiring enzyme-1 (IRE-1), GRP78/Bip, and LC3-II/LC3-I as well as ROS production in the human umbilical vein endothelial cells (HUVECs) in a dose and time-dependent manner. Both beclin-1 small interfering RNA and 3-methyladenine treatment predominantly mitigated VEGF-A-induced tube formation and migration of HUVECs, but they failed to elicit any notable effect on VEGF-A-increased expression of GRP78/Bip. Tauroursodeoxycholic acid not only obviously abolished VEGF-A-induced increase of IRE-1, GRP78/Bip, beclin-1 expression, and LC3-II/LC3-I, but also negated VEGF-A-induced tube formation and migration of HUVECs. Furthermore, N-acetyl- l-cysteine markedly abrogated VEGF-A-increased ROS production, IRE-1, GRP78/Bip, beclin-1 expression, and LC3-II/LC3-I in the HUVECs. Taken together, our data demonstrated that increased spontaneous production of VEGF-A may induce angiogenesis after AMI through initiating ROS-ER stress-autophagy axis in the vascular endothelial cells.

Melatonin Enhances Proliferation and Modulates Differentiation of Neural Stem Cells Via Autophagy in Hyperglycemia

Dysfunction of neural stem cells (NSCs) has been linked to fetal neuropathy, one of the most devastating complications of gestational diabetes. Several studies have demonstrated that melatonin (Mel) exerted neuroprotective actions in various stresses. However, the role of autophagy and the involvement of Mel in NSCs in hyperglycemia (HG) have not yet been fully established. Here, we found that HG increased autophagy and autophagic flux of NSCs as evidenced by increasing LC3B II/I ratio, Beclin-1 expression, and autophagosomes. Moreover, Mel enhanced NSCs proliferation and self-renewal in HG with decreasing autophagy and activated mTOR signaling. Consistently, inhibition of autophagy by 3-Methyladenine (3-Ma) could assist Mel effects above, and induction of autophagy by Rapamycin (Rapa) could diminish Mel effects. Remarkably, HG induced premature differentiation of NSCs into neurons (Map2 positive cells) and astrocytes (GFAP positive cells). Furthermore, Mel diminished HG-induced premature differentiation and assisted NSCs in HG differentiation as that in normal condition. Coincidentally, inhibiting of NSCs autophagy by 3-Ma assisted Mel to modulate differentiation. However, increasing NSCs autophagy by Rapa disturbed the Mel effects and retarded NSCs differentiation. These findings suggested that Mel supplementation could contribute to mimicking normal NSCs proliferation and differentiation in fetal central nervous system by inhibiting autophagy in the context of gestational diabetes. Stem Cells 2019;37:504-515.

Beneficial treatment effects of dietary nitrate supplementation on testicular injury in streptozotocin-induced diabetic male rats

RESEARCH QUESTION

Do low doses of dietary nitrate help to attenuate the progression of diabetic reproductive disorders in streptozotocin-induced diabetic male rats?

DESIGN

Fifty male Wistar rats were divided into five groups: controls receiving distilled water; controls receiving 100 mg/l nitrate in distilled water; diabetic rats receiving distilled water; diabetic rats receiving insulin 2-4 U/day of neutral protamine hagedorn insulin; and diabetic rats receiving 100 mg/l nitrate in distilled water. Diabetes was induced by 45 mg/kg streptozotocin. Nitrate and insulin treatment were started 4 weeks after diabetes induction for 8 weeks. Serum insulin, nitrogen oxide, stereology of testis, apoptosis, sperm parameters, and mRNA expression of Pdcd4, Pacs2, p53 and miR-449a were assessed at the end of the study.

RESULTS

Blood glucose, apoptotic index of seminiferous tubules and expression of p53, Pdcd4, and Pacs2 mRNA were significantly higher in the diabetic rats (P < 0.001). Decreased body weight, serum insulin and nitrogen oxide level, and miR-449a were observed in the diabetic group (P < 0.01 for insulin; P < 0.001 for others). Most sperm parameters and stereological results differed between diabetic and control rats; nitrate recovered almost all these alterations, including dead spermatozoa, sperm motility grade, sperm deformity index, spermatozoa with damaged DNA, malformations in abnormal spermatozoa, total volume of seminiferous tubule, germinal epithelium, capsule, lumen, interstitial tissue, seminiferous tubule diameter, germinal epithelium height, the number of spermatogenic, Sertoli and Leydig cells.

CONCLUSIONS

Treatment with sodium nitrate could modulate apoptosis, which is a major cause of diabetic testicular disorder. These experiments suggest that nitric oxide plays an important role in the function of the reproductive system.

Distinct role of autophagy on angiogenesis: highlights on the effect of autophagy in endothelial lineage and progenitor cells

Autophagy plays a critical role in the dynamic growth of each cell through different conditions. It seems that this intracellular mechanism acts as a two-edged sword against the numerous cell insults. Previously, autophagy was described in the context of cell activity and behavior, but little knowledge exists related to the role of autophagy in endothelial cells, progenitors, and stem cells biology from different tissues. Angiogenic behavior of endothelial lineage and various stem cells are touted as an inevitable feature in the restoration of different damaged tissues and organs. This capacity was found to be dictated by autophagy signaling pathway. This review article highlights the fundamental role of cell autophagic response in endothelial cells function, stem cells dynamic, and differentiation rate. It seems that elucidation of the mechanisms related to pro- and/or anti-angiogenic potential of autophagy inside endothelial cells and stem cells could help us to modulate stem cell therapeutic feature post-transplantation.

Protective effects of sodium nitrate against testicular apoptosis and spermatogenesis impairments in streptozotocin-induced diabetic male rats

AIMS

As nitric oxide (NO) production is essential for insulin signaling, glucose uptake, endothelial function, and regulation of apoptosis, the loss of bioavailable NO may be a mechanism underlying the development of diabetes complication. Dietary nitrate acts as a substrate for NO generation, thus serving as a physiological source of NO. This study evaluated the therapeutic effects of nitrate supplementation on the apoptosis-induced testicular disorders in diabetic rats.

MAIN METHODS

Fifty male Wistar rats were divided into five groups; control, control with 100 mg/L nitrate in distilled drinking water, diabetes, diabetes treated with 2-4 U/day NPH insulin, diabetes treated with 100 mg/L nitrate in distilled drinking water. After 8 weeks, blood samples, testis, and epididymis were collected to assess the apoptosis process and the stereology of testis tissue, sperm motility, morphology and DNA fragmentation, and also mRNA expression of miR-449a, p53, Pdcd4, and Pacs2 mRNA, as well as serum glucose, insulin, and NOx levels were investigated.

KEY FINDINGS

The results of this study indicated that nitrate treatment ameliorated the sperm parameters, testicular morphometrical and stereological alterations, reduced blood glucose, the number of TUNEL positive cells and tubules, and testicular expressions of p53, Pdcd4, and Pacs2 mRNA as well as increased body weight, serum insulin and NOx levels, and testicular expression of miR-449a in streptozotocin-induced diabetic rats.

SIGNIFICANCE

Our in vivo evidence revealed that nitrate treatment may has a favorable effect as an exogenous NO donor on experimental diabetic testicular damages in which NO bioavailability is impaired.

Effect of Runx2 silencing on autophagy and RANKL expression in osteoblasts

OBJECTIVE

This study aimed to investigate the effect of Runx2 silencing on autophagy and RANKL expression in mouse osteoblasts, and provide an experimental basis to assess obstacles in dental eruption.

METHODS

In accordance with previously reported methods, LVpFU-GW-016PSC60109-1 virus was used to transfect mouse osteoblasts (MOI = 40). Target gene expression was assessed via cytometer, and the effect of silencing Runx2 was assessed via a two-step quantitative real-time polymerase chain reaction (qRT-PCR)-based method. Western blotting was performed to assess LC3, Beclin-1 and RANKL expression.

RESULTS

As confirmed via qRT-PCR analysis, Runx2 was efficiently silenced in the experimental group (>90% efficiency). Western blotting revealed that LC3 and RANKL proteins were significantly down -regulated in the experimental group (group KD), their expression levels being particularly lower than those in the control group (group NC). However, Beclin-1 protein expression was not significantly different from that of the control.

CONCLUSION

Upon Runx2 silencing, autophagy-related proteins and RANKL were repressed in osteoblasts, thereby potentially causing the tooth eruption disorder.

Overexpression of miR‑17‑5p protects against high glucose‑induced endothelial cell injury by targeting E2F1‑mediated suppression of autophagy and promotion of apoptosis

E2 promoter binding factor 1 (E2F1) has been reported to have an important regulatory role in cell survival during hyperglycemic conditions; however, the mechanisms remain to be fully elucidated. Bioinformatics analyses have suggested that microRNA (miR)‑17‑5p targets the 3'untranslated region (3'UTR) of E2F1. The aim of the present study was to characterize the protective effect of miR‑17‑5p/E2F1 on human umbilical vein endothelial cells (HUVECs) under high glucose (HG) conditions, to confirm the regulatory effect of miR‑17‑5p on E2F1/AMP‑activated protein kinase α2 (AMPKα2)‑mediated apoptosis and E2F1/mammalian target of rapamycin complex 1 (mTORC1)‑mediated autophagy. Bifluorescein experiments were performed to characterize the interaction between miR‑17‑5p and E2F1. The Cell Counting Kit‑8 assay, flow cytometry, immunofluorescence, and reverse transcription‑quantitative polymerase chain reaction and western blot analyses were used to detect cell viability, apoptosis, autophagy, and relative mRNA and protein expression, respectively. The results showed that HG induced the downregulation of miR‑17‑5p and upregulation of E2F1 during HUVEC injury. The downregulation of E2F1 inhibited HG‑induced HUVEC dysfunction by suppressing mTORC1‑mediated inhibition of autophagy and AMPKα2‑mediated promotion of apoptosis. The results suggested that inhibiting the expression of E2F1 protected against HG‑induced HUVEC injury via the activation of autophagy. The overexpression of miR‑17‑5p inhibited E2F1‑mediated HUVEC injury under HG conditions, which was reversed following transfection with an E2F1‑overexpression vector. The bifluorescein experiments showed that miR‑17‑5p targeted the 3'UTR of E2F1. Taken together, the results suggested that the expression of miR‑17‑5p inhibited HG‑induced endothelial cell injury by targeting E2F1.

Knockdown of KPNA2 inhibits autophagy in oral squamous cell carcinoma cell lines by blocking p53 nuclear translocation

Oral squamous cell carcinoma (OSCC), one of the 10 most common types of neoplasms in the US, constitutes ~90% of all cases of oral malignancies. Chemoresistance and metastasis are difficult to avoid during the course of treatment, leading to a poor prognosis and a high mortality rate for patients with OSCC. Autophagy, a critical conserved cellular process, has been reported to be highly associated with the regulation of chemoresistance and metastasis of cancer cells. The present study investigated the role of karyopherin α2 (KPNA2), a member of the importin α family, which may serve an important role in p53 nucleocytoplasmic transport in the process of OSCC autophagy. In the CAL-27, SCC-15 and Tca8113 OSCC cell lines, we observed that the downregulation of KPNA2 suppressed cell migration and cisplatin resistance, using wound-healing, Transwell and CCK-8 assays. Additionally, the results of western blot analysis and transmission electron microscopy (TEM) analysis indicated that the knockdown of KPNA2 inhibited autophagy. We confirmed that the inhibition of autophagy with anti-autophagy agents decreased the migration and cisplatin resistance of OSCC cells. We hypothesized that the suppression of cell migration and cisplatin resistance induced by KPNA2 knockdown may be associated with the inhibition of autophagy. To identify the underlying mechanism, further experiments determined that KPNA2 affects the level of autophagy via regulating the p53 nuclear import. Thus, the present study demonstrated that the function of KPNA2 in the process of autophagy may be p53-dependent, and by regulating the translocation of p53, KPNA2 can support autophagy to promote the chemoresistance and metastasis of OSCC cells.

Docosahexaenoic acid reversed atherosclerotic changes in human endothelial cells induced by palmitic acid in vitro

Abnormal activity of atherosclerotic endothelial cells paving luminal surface of blood vessels has been described in many diseases. It has been reported that natural polyunsaturated fatty acids such as docosahexaenoic acid exert therapeutic effects in atherosclerotic condition. Human umbilical vein endothelial cells were treated with 1mM palmitic acid for 48 hours and exposed to 40μM docosahexaenoic acid for the next 24 hours. Real-time polymerase chain reaction analysis was used to measure the expression of PTX3, iNOS, and eNOS. The level of nitric oxide was detected by Griess reagent. The transcription level of genes participating in coagulation and blood pressure was studied by polymerase chain reaction array. Docosahexaenoic acid improved the survival rate by reducing apoptosis rate (P < .05). Compared with that of the group given palmitic acid, attenuation of proinflammatory status was indicated by reduced interleukin-6 (P < .05) and prostaglandin E₂ levels. All genes PTX3, iNOS, and eNOS were down-regulated after being exposed to docosahexaenoic acid. Nitric oxide contents were not changed in cells exposed to docosahexaenoic acid. Polymerase chain reaction array confirmed the reduction of LPA, PDGFβ, ITGA2, SERPINE1, and FGA after exposure to docosahexaenoic acid for 24 hours (P < .05). Docosahexaenoic acid had potential to blunt atherosclerotic changes in the modulation of genes controlling blood coagulation, pressure, and platelet function.

SIGNIFICANCE OF THE STUDY

The current experiment showed that docosahexaenoic acid could reverse atherosclerotic changes in human endothelial cells induced by palmitic acid. The increased levels of interleukin-6 and prostaglandin E₂ in atherosclerotic cells were returned to near-to-normal status. Gene expression analysis showed a reduced activity of genes participating in atherosclerotic endothelial cells treated by docosahexaenoic acid. The expression of genes related to cell clotting activity was also similar to that of normal cells.

A hybrid of coumarin and phenylsulfonylfuroxan induces caspase-dependent apoptosis and cytoprotective autophagy in lung adenocarcinoma cells

BACKGROUND

Lung adenocarcinoma is the most primary histologic subtype of non-small cell lung cancer (NSCLC). Compound 8b, a novel coumarin derivative with phenylsulfonylfuroxan group, shows significant antiproliferation activity against lung adenocarcinoma cell with low toxicity.

PURPOSE

This study aims to uncover the potential of compound 8b in relation to apoptosis as well as autophagy induction in lung adenocarcinoma cells.

STUDY DESIGN

The cytotoxicity and apoptosis of A549 and H1299 cells induced by compound 8b were detected by MTT, microscope and western blot analysis. Autophagy was determined by TEM, confocal microscopy and western blot analysis. Akt/mTOR and Erk signaling pathway were also examined by western blot analysis.

RESULTS

First, significant growth inhibition and caspase-dependent apoptosis were observed in compound 8b-treated A549 and H1299 cells. Then, we confirmed compound 8b-induced autophagy by autophagosomes formation, upregulated expression of autophagy-related protein LC3-II and autophagic flux. Importantly, abolishing autophagy using inhibitors and ATG5 siRNA enhanced the cytotoxicity of compound 8b, indicating the cytoprotective role of autophagy in lung adenocarcinoma. Further mechanistic investigations suggested that Akt/mTOR and Erk signaling pathways contributed to autophagy induction by compound 8b.

CONCLUSION

This results demonstrate that compound 8b induces caspase-dependent apoptosis as well as cytoprotective autophagy in lung adenocarcinoma cells, which may provide scientific evidence for developing this furoxan-based NO-releasing coumarin derivative as a potential anti-lung adenocarcinoma therapeutic agents.