PPARβ/δ accelerates bone regeneration in diabetic mellitus by enhancing AMPK/mTOR pathway-mediated autophagy

Recent advances on cyanidin-3-O-glucoside in preventing obesity-related metabolic disorders: A comprehensive review

Anthocyanins, found in various pigmented plants as secondary metabolites, represent a class of dietary polyphenols known for their bioactive properties, demonstrating health-promoting effects against several chronic diseases. Among these, cyanidin-3-O-glucoside (C3G) is one of the most prevalent types of anthocyanins. Upon consumption, C3G undergoes phases I and II metabolism by oral epithelial cells, absorption in the gastric epithelium, and gut transformation (phase II & microbial metabolism), with limited amounts reaching the bloodstream. Obesity, characterized by excessive body fat accumulation, is a global health concern associated with heightened risks of disability, illness, and mortality. This comprehensive review delves into the biodegradation and absorption dynamics of C3G within the gastrointestinal tract. It meticulously examines the latest research findings, drawn from in vitro and in vivo models, presenting evidence underlining C3G's bioactivity. Notably, C3G has demonstrated significant efficacy in combating obesity, by regulating lipid metabolism, specifically decreasing lipid synthesis, increasing fatty acid oxidation, and reducing lipid accumulation. Additionally, C3G enhances energy homeostasis by boosting energy expenditure, promoting the activity of brown adipose tissue, and stimulating mitochondrial biogenesis. Furthermore, C3G shows potential in managing various prevalent obesity-related conditions. These include cardiovascular diseases (CVD) and hypertension through the suppression of reactive oxygen species (ROS) production, enhancement of endogenous antioxidant enzyme levels, and inhibition of the nuclear factor-kappa B (NF-κB) signaling pathway and by exercising its cardioprotective and vascular effects by decreasing pulmonary artery thickness and systolic pressure which enhances vascular relaxation and angiogenesis. Type 2 diabetes mellitus (T2DM) and insulin resistance (IR) are also managed by reducing gluconeogenesis via AMPK pathway activation, promoting autophagy, protecting pancreatic β-cells from oxidative stress and enhancing glucose-stimulated insulin secretion. Additionally, C3G improves insulin sensitivity by upregulating GLUT-1 and GLUT-4 expression and regulating the PI3K/Akt pathway. C3G exhibits anti-inflammatory properties by inhibiting the NF-κB pathway, reducing pro-inflammatory cytokines, and shifting macrophage polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype. C3G demonstrates antioxidative effects by enhancing the expression of antioxidant enzymes, reducing ROS production, and activating the Nrf2/AMPK signaling pathway. Moreover, these mechanisms also contribute to attenuating inflammatory bowel disease and regulating gut microbiota by decreasing Firmicutes and increasing Bacteroidetes abundance, restoring colon length, and reducing levels of inflammatory cytokines. The therapeutic potential of C3G extends beyond metabolic disorders; it has also been found effective in managing specific cancer types and neurodegenerative disorders. The findings of this research can provide an important reference for future investigations that seek to improve human health through the use of naturally occurring bioactive compounds.

Enhancement of Bone Repair in Diabetic Rats with Metformin-Modified Silicified Collagen Scaffolds

Regenerating bone defects in diabetic rats presents a significant challenge due to the detrimental effects of reactive oxygen species and impaired autophagy on bone healing. To address these issues, a metformin-modified biomimetic silicified collagen scaffold is developed utilizing the principles of biomimetic silicification. In vitro and in vivo experiments demonstrated that the scaffold enhanced bone tissue regeneration within the diabetic microenvironment through the release of dual bio-factors. Further analysis reveals a potential therapeutic mechanism whereby these dual bio-factors synergistically promoted osteogenesis in areas of diabetic bone defects by improving mitochondrial autophagy and maintaining redox balance. The present study provides critical insights into the advancement of tissue engineering strategies aimed at bone regeneration in diabetic patients. The study also sheds light on the underlying biological mechanisms.

Inhibition of miR-542-3p augments autophagy to promote diabetic corneal wound healing

BACKGROUND

Autophagy has recently been shown to be critical for protecting peripheral nerve regeneration. This study explored the impact of miR-542-3p on diabetic corneal nerve regeneration and epithelial healing through the regulation of autophagy.

METHODS

A type 1 diabetes model was established in male mice through streptozotocin administration. Immunofluorescence staining of β-Tubulin III and sodium fluorescein staining were performed to observe corneal nerve fiber density and corneal epithelial healing, respectively. Western blotting, immunofluorescence and transmission electron microscopy were used to determine autophagy levels. Subconjunctival injection of RAPA and 3-MA altered autophagy levels; with them, we evaluated the role of autophagy in diabetic keratopathy. miRNA sequencing and bioinformatics analysis were performed to identify miRNA-mRNA networks with potential autophagy-regulating roles, and miR-542-3p was measured by quantitative real-time polymerase chain reaction (qRT-PCR). miR-542-3p antagomir was injected subconjunctivally to assess the role in diabetic corneal neuropathy.

RESULTS

Our data suggest that autophagy is suppressed in the diabetic corneal nerve and that activation of autophagy promotes diabetic corneal wound healing. We identified a potential autophagy-regulating miRNA-mRNA network in the diabetic trigeminal ganglion, in which miR-542-3p expression was significantly upregulated. Inhibition of miR-542-3p significantly enhanced the level of autophagy in trigeminal ganglion by upregulating ATG4D expression, thereby accelerating diabetic corneal nerve regeneration and epithelial healing.

CONCLUSIONS

Dysregulated autophagy is an important contributor to delayed diabetic corneal injury healing. Inhibiting miR-542-3p promotes diabetic corneal nerve regeneration and epithelial healing through autophagy activation by ATG4D.

An Overview of the Role of Peroxisome Proliferator-activated Receptors in Liver Diseases

Peroxisome proliferator-activated receptors (PPARs) are a superfamily of nuclear transcription receptors, consisting of PPARα, PPARγ, and PPARβ/δ, which are highly expressed in the liver. They control and modulate the expression of a large number of genes involved in metabolism and energy homeostasis, oxidative stress, inflammation, and even apoptosis in the liver. Therefore, they have critical roles in the pathophysiology of hepatic diseases. This review provides a general insight into the role of PPARs in liver diseases and some of their agonists in the clinic.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

Constitutively activated AMPKα1 protects against skeletal aging in mice by promoting bone-derived IGF-1 secretion

Senile osteoporosis is characterized by age-related bone loss and bone microarchitecture deterioration. However, little is known to date about the mechanism that maintains bone homeostasis during aging. In this study, we identify adenosine monophosphate-activated protein kinase alpha 1 (AMPKα1) as a critical factor regulating the senescence and lineage commitment of mesenchymal stem cells (MSCs). A phospho-mutant mouse model shows that constitutive AMPKα1 activation prevents age-related bone loss and promoted MSC osteogenic commitment with increased bone-derived insulin-like growth factor 1 (IGF-1) secretion. Mechanistically, upregulation of IGF-1 signalling by AMPKα1 depends on cAMP-response element binding protein (CREB)-mediated transcriptional regulation. Furthermore, the essential role of the AMPKα1/IGF-1/CREB axis in promoting aged MSC osteogenic potential is confirmed using three-dimensional (3D) culture systems. Taken together, these results can provide mechanistic insight into the protective effect of AMPKα1 against skeletal aging by promoting bone-derived IGF-1 secretion.

DPP-4 Inhibitors Suppress Tau Phosphorylation and Promote Neuron Autophagy through the AMPK/mTOR Pathway to Ameliorate Cognitive Dysfunction in Diabetic Mellitus

Dipeptidyl peptidase-4 (DPP-4) inhibitors have been considered as incretin-based agents that signal through GLP-1R. Our high-throughput RNA sequencing (RNA-seq) and bioinformatics methods indicated that GLP-1R, downregulated in diabetes mellitus (DM), was a potential target of DPP-4 inhibitors, which was further confirmed in DM rats. Thus, this study illuminated the alleviatory mechanism of DPP-4 on cognitive dysfunction in diabetes mellitus (DM), which may be associated with GLP-1R signaling. DM rats were administered with DPP-4 inhibitors, Chloroquine (an autophagy inhibitor), Exendin 9-39 (a GLP-1R antagonist), or Compound C (a specific inhibitor of AMPK). An in vitro model of DM was induced in rat hippocampal neuronal cell line H19-7 by exposure to high glucose (HG) and high fat (HF), followed by treatment with the above inhibitors and antagonists. It was found that cognitive dysfunction was promoted, and LC3 expression was lowered in DM rats by an autophagy inhibitor. The DPP-4 inhibitors decreased cognitive dysfunction, repressed Tau phosphorylation, and enhanced GLP-1R protein level, LC3 expression, and AMPK and mTOR phosphorylation in DM rats, while GLP-1R antagonist, an autophagy inhibitor, or AMPK inhibitor counteracted these effects. Such effects were also observed in HG/HF-induced neurons. In conclusion, our data elucidated the alleviatory mechanism of DPP-4 inhibitors in the cognitive dysfunction of DM rats via the AMPK/mTOR pathway.

Lignin/Puerarin Nanoparticle-Incorporated Hydrogel Improves Angiogenesis through Puerarin-Induced Autophagy Activation

Purpose

Puerarin is the main isoflavone extracted from Radix Puerariae lobata (Willd.) and exerts a strong protective effect on endothelial cells. This isoflavone also exerts proven angiogenic effects; however, the potential underlying mechanism has not been fully explored. Here in this work, we aimed to determine the proangiogenesis effect of a puerarin-attached lignin nanoparticle-incorporated hydrogel and explore the underlying mechanism.

Materials and Methods

Puerarin-attached lignin nanoparticles were fabricated and mixed with the GelMA hydrogel. After the hydrogel was characterized, the angiogenic effect was evaluated in a mouse hind-limb ischemia model. To further explore the mechanism of angiogenesis, human endothelial cell line EA.hy926 was exposure to different concentrations of puerarin. Wound healing assays and tube formation assays were used to investigate the effects of puerarin on cell migration and angiogenesis. qPCR and Western blotting were performed to determine the changes in the levels of angiogenesis indicators, autophagy indicators and PPARβ/δ. 3-MA was used to assess the role of autophagy in the puerarin-mediated angiogenesis effect in vivo and in vitro.

Results

The hydrogel significantly improved blood flow restoration in mice with hind-limb ischemia. This effect was mainly due to puerarin-mediated increases in the angiogenic capacity of endothelial cells and the promotion of autophagy activation. A potential underlying mechanism might be that puerarin-mediated activation of autophagy could induce an increase in PPARβ/δ expression.

Conclusion

The puerarin-attached lignin nanoparticle-incorporated hydrogel effectively alleviated blood perfusion in mice with hind-limb ischemia. Puerarin has a prominent proangiogenic effect. The potential mechanisms might be that puerarin-mediated autophagy activation and increase in PPARβ/δ.

Zoledronate Promotes Peri-Implant Osteogenesis in Diabetic Osteoporosis by the AMPK Pathway

Together with diabetic osteoporosis (DOP), diabetes patients experience poor peri-implant osteogenesis following implantation for dentition defects. Zoledronate (ZOL) is widely used to treat osteoporosis clinically. To evaluate the mechanism of ZOL for the treatment of DOP, experiments with DOP rats and high glucose-grown MC3T3-E1 cells were used. The DOP rats treated with ZOL and/or ZOL implants underwent a 4-week implant-healing interval, and then microcomputed tomography, biomechanical testing, and immunohistochemical staining were performed to elucidate the mechanism. In addition, MC3T3-E1 cells were maintained in an osteogenic medium with or without ZOL to confirm the mechanism. The cell migration, cellular actin content, and osteogenic differentiation were evaluated by a cell activity assay, a cell migration assay, as well as alkaline phosphatase, alizarin red S, and immunofluorescence staining. The mRNA and protein expression of adenosine monophosphate-activated protein kinase (AMPK), phosphorylated AMPK (p-AMPK), osteoprotegerin (OPG), receptor activator of nuclear factor kappa B ligand (RANKL), bone morphogenetic protein 2 (BMP2), and collagen type I (Col-I) were detected using real-time quantitative PCRs and western blot assays, respectively. In the DOP rats, ZOL markedly improved osteogenesis, enhanced bone strength and increased the expression of AMPK, p-AMPK, and Col-I in peri-implant bones. The in vitro findings showed that ZOL reversed the high glucose-induced inhibition of osteogenesis via the AMPK signaling pathway. In conclusion, the ability of ZOL to promote osteogenesis in DOP by targeting AMPK signaling suggests that therapy with ZOL, particularly simultaneous local and systemic administration, may be a unique approach for future implant repair in diabetes patients.

Dexmedetomidine Alleviates Abdominal Aortic Aneurysm by Activating Autophagy Via AMPK/mTOR Pathway

BACKGROUND

Abdominal aortic aneurysms (AAA) are a critical global health issue with increasing prevalence. Dexmedetomidine (DEX) is a highly selective α2-adrenoceptor agonist that has previously been shown to play a protective role in AAA. Nevertheless, the mechanisms underlying its protection effect remain not fully understood.

METHODS

A rat AAA model was established via intra-aortic porcine pancreatic elastase perfusion with or without DEX administration. The abdominal aortic diameters of rats were measured. Hematoxylin-eosin and Elastica van Gieson staining were conducted for histopathological observation. TUNEL and immunofluorescence staining were utilized to detect cell apoptosis and α-SMA/LC3 expression in the abdominal aortas. Protein levels were determined using western blotting.

RESULTS

DEX administration repressed the dilation of aortas, alleviated pathological damage and cell apoptosis, and suppressed phenotype switching of vascular smooth muscle cells (VSMCs). Moreover, DEX activated autophagy and regulated the AMP-activated protein kinase/mammalian target of the rapamycin (AMPK/mTOR) signaling pathway in AAA rats. Administration of the AMPK inhibitor attenuated the DEX-mediated ameliorative effects on AAA in rats.

CONCLUSION

DEX ameliorates AAA in rat models by activating autophagy via the AMPK/mTOR pathway.

PTP1B knockdown alleviates BMSCs senescence via activating AMPK-mediated mitophagy and promotes osteogenesis in senile osteoporosis

The senescence of bone marrow mesenchymal stem cells (BMSCs) is the basis of senile osteoporosis (SOP). Targeting BMSCs senescence is of paramount importance for developing anti-osteoporotic strategy. In this study, we found that protein tyrosine phosphatase 1B (PTP1B), an enzyme responsible for tyrosine dephosphorylation, was significantly upregulated in BMSCs and femurs with advancing chronological age. Therefore, the potential role of PTP1B in BMSCs senescence and senile osteoporosis was studied. Firstly, significantly upregulated PTP1B expression along with impaired osteogenic differentiation capacity was observed in D-galactose (D-gal)-induced BMSCs and naturally-aged BMSCs. Furthermore, PTP1B silencing could effectively alleviate senescence, improve mitochondrial dysfunction, and restore osteogenic differentiation in aged BMSCs, which was attributable to enhanced mitophagy mediated by PKM2/AMPK pathway. In addition, hydroxychloroquine (HCQ), an autophagy inhibitor, significantly reversed the protective effects from PTP1B knockdown. In SOP animal model, transplantation of LV^sh-PTP1B-transfected D-gal-induced BMSCs harvested double protective effects, including increased bone formation and reduced osteoclastogenesis. Similarly, HCQ treatment remarkably suppressed osteogenesis of LV^sh-PTP1B-transfected D-gal-induced BMSCs in vivo. Taken together, our data demonstrated that PTP1B silencing protects against BMSCs senescence and mitigates SOP via activating AMPK-mediated mitophagy. Targeting PTP1B may represent a promising interventional strategy to attenuate SOP.

Osteogenesis of bone marrow mesenchymal stem cell in hyperglycemia

Diabetes mellitus (DM) has been shown to be a clinical risk factor for bone diseases including osteoporosis and fragility. Bone metabolism is a complicated process that requires coordinated differentiation and proliferation of bone marrow mesenchymal stem cells (BMSCs). Owing to the regenerative properties, BMSCs have laid a robust foundation for their clinical application in various diseases. However, mounting evidence indicates that the osteogenic capability of BMSCs is impaired under high glucose conditions, which is responsible for diabetic bone diseases and greatly reduces the therapeutic efficiency of BMSCs. With the rapidly increasing incidence of DM, a better understanding of the impacts of hyperglycemia on BMSCs osteogenesis and the underlying mechanisms is needed. In this review, we aim to summarize the current knowledge of the osteogenesis of BMSCs in hyperglycemia, the underlying mechanisms, and the strategies to rescue the impaired BMSCs osteogenesis.

mTOR Signaling Pathway in Bone Diseases Associated with Hyperglycemia

The interplay between bone and glucose metabolism has highlighted hyperglycemia as a potential risk factor for bone diseases. With the increasing prevalence of diabetes mellitus worldwide and its subsequent socioeconomic burden, there is a pressing need to develop a better understanding of the molecular mechanisms involved in hyperglycemia-mediated bone metabolism. The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that senses extracellular and intracellular signals to regulate numerous biological processes, including cell growth, proliferation, and differentiation. As mounting evidence suggests the involvement of mTOR in diabetic bone disease, we provide a comprehensive review of its effects on bone diseases associated with hyperglycemia. This review summarizes key findings from basic and clinical studies regarding mTOR's roles in regulating bone formation, bone resorption, inflammatory responses, and bone vascularity in hyperglycemia. It also provides valuable insights into future research directions aimed at developing mTOR-targeted therapies for combating diabetic bone diseases.

Handelin protects human skin keratinocytes against ultraviolet B-induced photodamage via autophagy activation by regulating the AMPK-mTOR signaling pathway

Handelin is a natural ingredient extracted from Chrysanthemum boreale flowers that has been shown to decrease stress-related cell death, prolong lifespan, and promote anti-photoaging. However, whether handelin inhibits ultraviolet (UV) B stress-induced photodamage remains unclear. In the present study, we investigate whether handelin has protective properties on skin keratinocytes under UVB irradiation. Human immortalized keratinocytes (HaCaT keratinocytes) were pretreated with handelin for 12 h before UVB irradiation. The results indicated that handelin protects keratinocytes against UVB-induced photodamage by activating autophagy. However, the photoprotective effect of handelin was suppressed by an autophagic inhibitor (wortmannin) or the transfection of keratinocytes with a small interfering RNA targeting ATG5. Notably, handelin reduced mammalian target of rapamycin (mTOR) activity in UVB-irradiated cells in a manner similar to that shown by the mTOR inhibitor rapamycin. Adenosine monophosphate-activated protein kinase (AMPK) activity was also induced by handelin in UVB-damaged keratinocytes. Finally, certain effects of handelin, including autophagy induction, mTOR activity inhibition, AMPK activation, and reduction of cytotoxicity, were suppressed by an AMPK inhibitor (compound C). Our data suggest that handelin effectively prevents photodamage by protecting skin keratinocytes against UVB-induced cytotoxicity via the regulation of AMPK/mTOR-mediated autophagy. These findings provide novel insights that can aid the development of therapeutic agents against UVB-induced keratinocyte photodamage.

Integrated network pharmacology, transcriptomics and metabolomics analysis to reveal the mechanism of salt Eucommia cortex in the treatment of chronic kidney disease mineral bone disorders via the PPARG/AMPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The skeletal complications associated with chronic kidney diseases from stages 3-5 in individuals are called Chronic Kidney Disease-Mineral Bone Disorder (CKD-MBD), which increases the incidence of cardiovascular diseases drastically and affects the quality of life of patients seriously. Eucommia cortex has the effect of tonifying kidneys and strengthening bones, and salt Eucommia cortex is one of the most commonly used traditional Chinese medicines in the clinical treatment of CKD-MBD instead of Eucommia cortex. However, its mechanism still remains unexplored.

AIM OF THE STUDY

The aim of this study was to investigate the effects and mechanisms of salt Eucommia cortex on CKD-MBD by integrating network pharmacology, transcriptomics, and metabolomics.

MATERIALS AND METHODS

The CKD-MBD mice induced by 5/6 nephrectomy and low calcium/high phosphorus diet were treated with salt Eucommia cortex. The renal functions and bone injuries were evaluated by serum biochemical detection, histopathological analyses, and femur Micro-CT examinations. Differentially expressed genes (DEGs) between the control group and model group, model group and high-dose Eucommia cortex group, model group and high-dose salt Eucommia cortex group were analyzed by transcriptomic analysis. The differentially expressed metabolites (DEMs) between the control group and model group, model group and high-dose Eucommia cortex group, model group and high-dose salt Eucommia cortex group were analyzed by metabolomics analysis.The common targets and pathways were obtained by integrating transcriptomics, metabolomics and network pharmacology, which were identified and verified by in vivo experiments.

RESULTS

The negative impacts on the renal functions and bone injuries were alleviated with salt Eucommia cortex treatment effectively. Compared with CKD-MBD model mice, the levels of serum BUN, Ca and urine Upr were significantly decreased in the salt Eucommia cortex group. And the Integrated network pharmacology, transcriptomics and metabolomics analysis revealed that Peroxisome Proliferative Activated Receptor, Gamma (PPARG) was the only common target, mainly involved by AMPK signaling pathways. The activation of PPARG in the kidney tissue was significantly decreased in CKD-MBD mice but increased in the salt Eucommia cortex treatment. The AMPK signaling pathway were verified that AMPK expression levels were decreased in CKD-MBD mice but increased in the salt Eucommia cortex treatment.

CONCLUSIONS

Our study presented that salt Eucommia cortex alleviated the negative impact of CKD-MBD on the renal injury and bone injury of mice induced by 5/6 nephrectomy with the low calcium/high phosphorus diet effectively, which is highly likely achieved through the PPARG/AMPK signaling pathway.

Advanced glycation end products inhibit the osteogenic differentiation potential of adipose-derived stem cells in mice through autophagy

BACKGROUND

Diabetes mellitus (DM) microenvironment will accelerate the accumulation of Advanced glycation end products (AGEs), adipose-derived stem cells (ASCs) have poor osteogenesis in the DM microenvironment. Studies suggest autophagy plays a vital role in osteogenesis, but the mechanism of the altered osteogenic potential of ASCs has not been elucidated. Bone tissue engineering by ASCs is widely used in the treatment of bone defects with diabetic osteoporosis (DOP). Therefore, it is meaningful to explore the effect of AGEs on the osteogenic differentiation potential of ASCs and its potential mechanism for the repair of bone defects in DOP.

MATERIALS AND METHODS

ASCs in C57BL/6 mice were isolated, cultured, then treated with AGEs, subsequently, cell viability and proliferation were detected through Cell Counting Kit 8 assay. 3-Methyladenine (3-MA), an autophagic inhibitor used to inhibit autophagic levels. Rapamycin (Rapa), an autophagy activator that further activated autophagy levels by inhibiting mTOR.The osteogenesis and autophagy changes of ASCs were analyzed by flow cytometry, qPCR, western blot, immunofluorescence, alkaline phosphatase (ALP) and alizarin red staining.

RESULTS

AGEs reduced the autophagy level and osteogenic potential of ASCs. After 3-MA reduced autophagy, the osteogenic potential of ASCs also decreased. AGEs co-treatment with 3-MA, the levels of osteogenesis and autophagy reduced more significantly. When autophagy was activated by Rapa, it was found that it could rescue the reduced osteogenic potential of AGEs.

CONCLUSIONS

AGEs reduce the osteogenic differentiation potential of ASCs through autophagy, and may provide a reference for the treatment of bone defects with diabetes osteoporosis.

Cannabinoids And Cannabinoid-Like Compounds: Biochemical Characterization And Pharmacological Perspectives

Publication interest in cannabinoids, including phytocannabinoids, endogenous cannabinoids, synthetic cannabinoids and cannabinomimetic compounds, is due to the therapeutic potential of these compounds in inflammatory pathology. Since recent years, scientific interest was focused on compounds with cannabinomimetic activity. The therapeutic use of phytocannabinoids and endocannabinoids is somewhat limited due to unresolved issues of dosing, toxicity and safety in humans, while cannabinoid-like compounds combine similar therapeutic effects with a high confirmed safety. Targets for endocannabinoids and phytocannabinoids are endocannabinoid receptors 1 and 2, G protein-coupled receptors (GPCRs), peroxisome proliferator-activated receptors (PPARs), and transient receptor potential ion channels (TRPs). Non-endocannabinoid N-acylethanolamines do not interact with cannabinoid receptors and exhibit agonist activity towards non-cannabinoid receptors, such as PPARs, GPCRs and TRPs. This literature review includes contemporary information on the biological activity, metabolism and pharmacological properties of cannabinoids and cannabinoid-like compounds, as well as their receptors. We established that only a few studies were devoted to the relationship of non-endocannabinoid N-acylethanolamines with non-cannabinoid receptors, such as PPARs, GPCRs, and also with TRPs. We have focused on issues that were insufficiently covered in the published sources in order to identify gaps in existing knowledge and determine the prospects for scientific research.

Glucagon-like peptide-1 receptor regulates receptor of advanced glycation end products in high glucose-treated rat mesangial cells

BACKGROUND

Hyperglycemia-induced advanced glycation end products (AGEs) and receptor for AGEs (RAGEs) play major roles in diabetic nephropathy progression. In previous study, both glucagon-like peptide-1 (GLP-1) and peroxisome proliferator-activated receptors delta (PPARδ) agonists were shown to have anti-inflammatory effect on AGE-treated rat mesangial cells (RMCs). The interaction among PPARδ agonists, GLP-1, and AGE-RAGE axis is, however, still unclear.

METHODS

In this study, the individual and synergic effect of PPARδ agonist (L-165 041) and siRNA of GLP-1 receptor (GLP-1R) on the expression of GLP-1, GLP-1R, RAGE, and cell viability in AGE-treated RMCs were investigated.

RESULTS

L-165 041 enhanced GLP-1R mRNA and protein expression only in the presence of AGE. The expression of RAGE mRNA and protein was enhanced by AGE, attenuated by L-165 041, and siRNA of GLP-1R reversed L-165 041-induced inhibition. Cell viability was also inhibited by AGE. L-165 041 attenuated AGE-induced inhibition and siRNA GLP-1R diminished L-165 041 effect.

CONCLUSION

PPARδ agonists increase GLP-1R expression on RMC in the presence of AGE. PPARδ agonists also attenuate AGE-induced upregulated RAGE expression and downregulated cell viability. The effect of PPARδ agonists needs the cooperation of GLP-1R activation.

Ginsenoside Rg1 Ameliorates Pancreatic Injuries via the AMPK/mTOR Pathway in vivo and in vitro

BACKGROUND

The main propanaxatriol-type saponin found in ginseng (Panax ginseng C. A. Mey), ginsenoside Rg1 (G-Rg1), has bioactivities that include anti-inflammatory, antioxidant, and anti-diabetic properties. This study aimed to investigate the effects of G-Rg1 on streptozotocin (STZ)-induced Type 1 Diabetes mellitus (T1DM) mice and the insulin-secreting cell line in RIN-m5F cells with high-glucose (HG) treatment.

METHODS

The STZ-induced DM mice model was treated with G-Rg1 alone or combined with 3-Methyladenine (3-MA, an autophagy inhibitor)/rapamycin (RAPA, an autophagy activator) for 8 weeks, and levels of glucose and lipid metabolism, histopathological changes, as well as autophagy and apoptosis of relevant markers were estimated. In vitro, the HG-induced RIN-m5F cells were treated with G-Rg1, 3-MA, and Compound C (CC), an AMPK inhibitor, or their combinations to estimate the influences on cell apoptosis, autophagy, and AMPK/mTOR pathway-associated target gene levels.

RESULTS

G-Rg1 treatment attenuated glucose and lipid metabolism disorder and pancreatic fibrosis in diabetic mice. In addition, subdued autophagy and p-AMPK protein expression, and enhanced p-mTOR protein expression and apoptosis levels in TIDM mice and HG-induced RIN-m5F cells were ameliorated by G-Rg1 treatment. Furthermore, these anti-apoptosis effects of G-Rg1 were partially abolished by 3-MA and CC.

CONCLUSION

Our findings revealed that G-Rg1 exhibits strong anti-apoptosis ability in pancreatic tissues of type 1 diabetic mice and HG-induced RIN-m5F cells, and the mechanisms involved in activating AMPK and inhibiting mTOR-mediated autophagy, indicating that G-Rg1 may have the therapeutic and preventive potential for treating pancreatic injury in diabetic patients.

Polydopamine-mediated graphene oxide and nanohydroxyapatite-incorporated conductive scaffold with an immunomodulatory ability accelerates periodontal bone regeneration in diabetes

Regenerating periodontal bone tissues in the aggravated inflammatory periodontal microenvironment under diabetic conditions is a great challenge. Here, a polydopamine-mediated graphene oxide (PGO) and hydroxyapatite nanoparticle (PHA)-incorporated conductive alginate/gelatin (AG) scaffold is developed to accelerate periodontal bone regeneration by modulating the diabetic inflammatory microenvironment. PHA confers the scaffold with osteoinductivity and PGO provides a conductive pathway for the scaffold. The conductive scaffold promotes bone regeneration by transferring endogenous electrical signals to cells and activating Ca²⁺ channels. Moreover, the scaffold with polydopamine-mediated nanomaterials has a reactive oxygen species (ROS)-scavenging ability and anti-inflammatory activity. It also exhibits an immunomodulatory ability that suppresses M1 macrophage polarization and activates M2 macrophages to secrete osteogenesis-related cytokines by mediating glycolytic and RhoA/ROCK pathways in macrophages. The scaffold induces excellent bone regeneration in periodontal bone defects of diabetic rats because of the synergistic effects of good conductive, ROS-scavenging, anti-inflammatory, and immunomodulatory abilities. This study provides fundamental insights into the synergistical effects of conductivity, osteoinductivity, and immunomodulatory abilities on bone regeneration and offers a novel strategy to design immunomodulatory biomaterials for treatment of immune-related diseases and tissue regeneration.

•

The conductive PGO-PHA-AG scaffold can activate Ca²⁺ channels.

•The PGO-PHA-AG scaffold had ROS-scavenging and anti-inflammatory activities.

•The scaffold exhibited an immunomodulatory ability.

•The scaffold induced excellent periodontal bone regeneration in diabetes.

Identification of differentially expressed autophagy genes associated with osteogenic differentiation in human bone marrow mesenchymal stem cells

BACKGROUND

Mesenchymal stem cells derived from human tissues have been widely used for tissue regeneration because of their strong self-renewal capacity and multi-potential properties. Autophagy plays a vital role in maintaining bone homeostasis. However, the mechanism underlying this role for autophagy in the osteogenic differentiation of mesenchymal stem cells remains to be elucidated.

METHODS

Two microarray datasets were downloaded from the GEO database. Fourteen bone marrow mesenchymal stem cell samples comprising control and induction groups were selected to identify differentially expressed autophagy-related genes via multiple bioinformatics approaches, followed by functional analysis. Interactions among differentially expressed autophagy genes, miRNAs, and transcription factors were analyzed and visualized using Cytoscape software. The association between hub differentially expressed genes and autophagy was validated by qRT-PCR.

RESULTS

Ten autophagy-related genes (including VPS8, NDRG4, and CYBB) were identified as osteogenic hub genes. Correlation analysis revealed that CYBB was highly correlated with the sensitivity to multiple drugs, such as imexon, megestrol acetate, and isotretinoin. The regulatory network displayed a complex connection among miRNAs, transcription factors, and differentially expressed autophagy genes. Friends' analysis showed that NDRG4 was highly closely related to other hub genes (P < 0.05). Furthermore, NDRG4 expression was downregulated in the induction group (P < 0.01). NDRG4 was significantly correlated with infiltrating immune cells, including monocytes, eosinophils, type 17 T helper cells, neutrophils, activated CD8 T cells, and immature B cells. Levels of the 10 autophagy-related genes (including VPS8, NDRG4, and CYBB) were successfully validated based on in vitro experiments.

CONCLUSION

We identified candidate molecules to further investigate their functions in osteogenesis, providing novel insights into the role of autophagy in mesenchymal stem cell differentiation.

Preclinical Studies of Natural Products Targeting the Gut Microbiota: Beneficial Effects on Diabetes

Diabetes mellitus (DM) is a serious metabolic disease characterized by persistent hyperglycemia, with a continuously increasing morbidity and mortality. Although traditional treatments including insulin and oral hypoglycemic drugs maintain blood glucose levels within the normal range to a certain extent, there is an urgent need to develop new drugs that can effectively improve glucose metabolism and diabetes-related complications. Notably, accumulated evidence implicates that the gut microbiota is unbalanced in DM individuals and is involved in the physiological and pathological processes of this metabolic disease. In this review, we introduce the molecular mechanisms by which the gut microbiota contributes to the development of DM. Furthermore, we summarize the preclinical studies of bioactive natural products that exert antidiabetic effects by modulating the gut microbiota, aiming to expand the novel therapeutic strategies for DM prevention and management.