Kakonein restores diabetes-induced endothelial junction dysfunction via promoting autophagy-mediated NLRP3 inflammasome degradation

Design and Self-Assembly of Peptide-Copolymer Conjugates into Nanoparticle Hydrogel for Wound Healing in Diabetes

Background

Delayed wound healing in skin injuries has become a significant problem in clinics, seriously affecting and even threatening life and health. Recently, research interest has increased in developing wound dressings containing bioactive compounds capable of improving outcomes for complex healing needs.

Methods

In this study, Puerarin-loaded nanoparticles (Pue-NPs) were prepared using the cell-penetrating peptide-poly (lactic-co-glycolic acid) (CPP-PLGA) as a drug carrier by the emulsified solvent evaporation method. Then, they were added into poly (acrylic acid) to obtain a self-assembled nanocomposite hydrogels (SANHs) drug delivery system using the co-polymerization method. The particle size, zeta potential, and micromorphology of Pue-NPs were measured; the appearance, mechanical properties, adhesive strength, and biological activity of SANHs were performed. Finally, the potential of SANHs for wound healing was further evaluated in streptozotocin-induced diabetic mice.

Results

Pue-NPs were regularly spherical, with an average particle size of 134.57 ± 1.42 nm and a zeta potential of 2.14 ± 0.78 mV. SANHs was colorless and transparent with a honeycomb-like porous structure and had an excellent swelling ratio (917%), water vapor transmission rate (3077 g·m-2·day-1), mechanical properties (Young's modulus of 18 kPa, elongation at break of 307%), and adhesive strength (15.5 kPa). SANHs exhibited sustained release of Pue over 48h, with a cumulative release of 55.60 ± 6.01%. In vitro tests revealed that the SANHs presented a 92.22% antibacterial rate against Escherichia coli after 4h, and a 61.91% scavenging rate of 1.1-diphenyl-2-trinitrophenylhydrazine (DPPH) radical. In vivo experiments showed that SANHs accelerated wound repair by reducing the inflammatory response at the wound site, promoting angiogenesis, and facilitating epidermal regeneration and collagen deposition.

Conclusion

In conclusion, we successfully prepared SANHs. Our results show that SANHs have excellent performance and improves wound healing in diabetic mice model, indicating that it can be used to develop an effective strategy for the treatment of diabetic wounds.

Pharmacological targets at the lysosomal autophagy-NLRP3 inflammasome crossroads

Many aspects of cell homeostasis and integrity are maintained by the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome. The NLRP3 oligomeric protein complex assembles in response to exogenous and endogenous danger signals. This inflammasome has also been implicated in the pathogenesis of a range of disease conditions, particularly chronic inflammatory diseases. Given that NLRP3 modulates autophagy, which is also a key regulator of inflammasome activity, excessive inflammation may be controlled by targeting this intersecting pathway. However, specific niche areas of NLRP3-autophagy interactions and their reciprocal regulatory mechanisms remain underexplored. Consequently, we lack treatment methods specifically targeting this pivotal axis. Here, we discuss the potential of such strategies in the context of autoimmune and metabolic diseases and propose some research avenues.

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.

Pharmacological Activity, Pharmacokinetics, and Clinical Research Progress of Puerarin

As a kind of medicine and food homologous plant, kudzu root (Pueraria lobata (Willd.) Ohwi) is called an "official medicine" in Chinese folk medicine. Puerarin is the main active component extracted from kudzu root, and its structural formula is 8-β-D-grapes pyranose-4, 7-dihydroxy isoflavone, with a white needle crystal; it is slightly soluble in water, and its aqueous solution is colorless or light yellow. Puerarin is a natural antioxidant with high health value and has a series of biological activities such as antioxidation, anti-inflammation, anti-tumor effects, immunity improvement, and cardio-cerebrovascular and nerve cell protection. In particular, for the past few years, it has also been extensively used in clinical study. This review focuses on the antioxidant activity of puerarin, the therapy of diverse types of inflammatory diseases, various new drug delivery systems of puerarin, the "structure-activity relationship" of puerarin and its derivatives, and pharmacokinetic and clinical studies, which can provide a new perspective for the puerarin-related drug research and development, clinical application, and further development and utilization.

Biejiajian Pill Ameliorates Diabetes-Associated Atherosclerosis through Inhibition of the NLRP3 Inflammasome

Objective

To research the efficacy of Biejiajian pill (BJJ) on diabetes-associated atherosclerosis and explore its subsequent mechanisms.

Methods

Diabetes-associated atherosclerosis (AS) was established in apolipoprotein E knockout (ApoE^−/−) mice using high-fat diet and streptozotocin. Atorvastatin (ATV, 10 mg/kg/day) or BJJ-L (BJJ low-dose, 0.9 g/kg/day), BJJ-M (BJJ medium-dose, 1.8 g/kg/day), and BJJ-H (BJJ high-dose, 3.6 g/kg/day) were administered to diabetic ApoE^−/− mice for 12 continuous weeks. The normal control group consisted of 10 male C57BL/6J mice. Atherosclerosis plaques, vascular endothelial function, fasting blood glucose, lipid metabolism, inflammatory factors, NLRP3 inflammasome expression, and mitochondria and autophagy changes were evaluated.

Results

The atherosclerotic lesions areas in the aortas were analyzed through Oil Red O and H&E staining, and they were reduced in the BJJ-H and BJJ-M groups. In the BJJ group, endothelin-1 (ET-1) levels were decreased, whereas endothelial nitric oxide synthase (eNOS) was increased. Fasting blood glucose levels in the BJJ and ATV groups were gradually decreased. Lipid metabolism parameters such as TG, TC, and LDL-C were reduced, while HDL-C was elevated in BJJ groups. The serum IL-1β and IL-18 were decreased under BJJ therapy. The aortic mRNA and protein expressions of NF-κB, TXNIP, NLRP3, ASC, caspase-1, and IL-1β were inhibited in BJJ-H and BJJ-M groups, especially in the BJJ-H group. Electron microscopy revealed an increase in autophagy in each treatment group.

Conclusions

The findings reveal that BJJ could alleviate diabetic atherosclerosis in diabetic ApoE^−/− mice by inhibiting NLRP3 inflammasome.

Potential Mechanisms and Effects of Chinese Medicines in Treatment of Diabetic Atherosclerosis by Modulating NLRP3 Inflammasome: A Narrative Review

Nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) is an intracellular sensor that detects endogenous danger signals and environmental irritants to assemble into the NLRP3 inflammasome. Activation of the NLRP3 inflammasome leads to the secretion of the proinflammatory cytokines interleutkin (IL)-1β and IL-18 and induces pyroptosis. Recent studies have shown that the NLRP3 inflammasome participates in the initiation and progression of diabetic atherosclerosis through pathological mechanisms such as β-cell dysfunction, insulin resistance, endothelial cell dysfunction, monocyte adhesion and infiltration, and smooth muscle cell proliferation and migration. In diabetic atherosclerosis, Chinese medicine has been proven effective for the inflammatory response mediated by the NLRP3 inflammasome. This review summarizes the latest progress on the NLRP3 inflammasome in the pathogenesis and potential Chinese medicine treatment of diabetic atherosclerosis.

Kakonein restores diabetes-induced endothelial junction dysfunction via promoting autophagy-mediated NLRP3 inflammasome degradation

In diabetes‐induced complications, inflammatory‐mediated endothelial dysfunction is the core of disease progression. Evidence shows that kakonein, an isoflavone common in Pueraria, can effectively treat diabetes and its complications. Therefore, we explored whether kakonein protects cardiovascular endothelial function by inhibiting inflammatory responses. In this study, C57BL/6J mice were injected with streptozocin to establish a diabetes model and treated with kakonein or metformin for 7 days. The protective effect of kakonein on cardiovascular endothelial junctions and NLRP3 inflammasome activation was verified through immunofluorescence and ELISA assay. In addition, the regulation of autophagy on the NLRP3 inflammasome was investigated through Western blot, immunofluorescence and RT‐qPCR. Results showed that kakonein restored the function of endothelial junctions and inhibited the assembly and activation of the NLRP3 inflammasome. Interestingly, kakonein decreased the expression of NLRP3 inflammasome protein by not reducing the transcriptional levels of NLRP3 and caspase‐1. Kakonein activated autophagy in an AMPK‐dependent manner, which reduced the activation of the NLRP3 inflammasome. In addition, kakonein inhibited both hyperglycaemia‐induced cardiovascular endothelial junction dysfunction and NLRP3 inflammasome activation, similar to autophagy agonist. Our findings indicated that kakonein exerts a protective effect on hyperglycaemia‐induced chronic vascular disease by regulating the NLRP3 inflammasome through autophagy.