Asiatic acid from Cyclocarya paliurus regulates the autophagy-lysosome system via directly inhibiting TGF-β type I receptor and ameliorates diabetic nephropathy fibrosis

Asiatic acid induces ferroptosis of RA-FLS via the Nrf2/HMOX1 pathway to relieve inflammation in rheumatoid arthritis

BACKGROUND

Ferroptosis is a distinct iron-dependent non-apoptotic type of programmed cell death that is implicated in the pathophysiology of rheumatoid arthritis (RA). Although asiatic acid (AA) is documented to have significant anti-inflammatory effects in various diseases, it is not known whether it can regulate RA via ferroptosis.

METHODS

The effects of AA on rheumatoid arthritis fibroid-like synoviocytes (RA-FLS) were assessed in vitro, and a rat model of type II collagen-induced arthritis (CIA) was established to evaluate the effectiveness of AA treatment in vivo.

RESULTS

AA significantly reduced both viability and colony formation in cultured RA-FLS, while increasing the levels of reactive oxygen species (ROS), ferrous iron (Fe2+), malondialdehyde (MDA), and lactate dehydrogenase (LDH), as well as the expression of COX2. Furthermore, AA induced ferroptosis in RA-FLS by promoting Fe2+ accumulation through downregulation of the expression of Keap1 and FTH1 and upregulation of Nrf2 and HMOX1. In vivo, AA treatment was found to reduce toe swelling and the arthritis score in CIA rats, as well as relieve inflammation and ankle damage and significantly upregulate the expression of Nrf2 and HMOX1 in the synovial fluid.

CONCLUSION

Treatment with AA significantly reduced the viability of RA-FLS and triggered ferroptosis by promoting accumulation of Fe2+via the Nrf2-HMOX1 pathway, and was effective in relieving inflammation in CIA model rats. These findings suggest that the use of AA may be a promising strategy for the clinical treatment of RA.

Integrated oral microgel system ameliorates renal fibrosis by hitchhiking co-delivery and targeted gut flora modulation

BACKGROUND

Renal fibrosis is a progressive process associated with chronic kidney disease (CKD), contributing to impaired kidney function. Active constituents in traditional Chinese herbs, such as emodin (EMO) and asiatic acid (AA), exhibit potent anti-fibrotic properties. However, the oral administration of EMO and AA results in low bioavailability and limited kidney accumulation. Additionally, while oral probiotics have been accepted for CKD treatment through gut microbiota modulation, a significant challenge lies in ensuring their viability upon administration. Therefore, our study aims to address both renal fibrosis and gut microbiota imbalance through innovative co-delivery strategies.

RESULTS

In this study, we developed yeast cell wall particles (YCWPs) encapsulating EMO and AA self-assembled nanoparticles (NPYs) and embedded them, along with Lactobacillus casei Zhang, in chitosan/sodium alginate (CS/SA) microgels. The developed microgels showed significant controlled release properties for the loaded NPYs and prolonged the retention time of Lactobacillus casei Zhang (L. casei Zhang) in the intestine. Furthermore, in vivo biodistribution showed that the microgel-carried NPYs significantly accumulated in the obstructed kidneys of rats, thereby substantially increasing the accumulation of EMO and AA in the impaired kidneys. More importantly, through hitchhiking delivery based on yeast cell wall and positive modulation of gut microbiota, our microgels with this synergistic strategy of therapeutic and modulatory interactions could regulate the TGF-β/Smad signaling pathway and thus effectively ameliorate renal fibrosis in unilateral ureteral obstruction (UUO) rats.

CONCLUSION

In conclusion, our work provides a new strategy for the treatment of renal fibrosis based on hitchhiking co-delivery of nanodrugs and probiotics to achieve synergistic effects of disease treatment and targeted gut flora modulation.

Targeting autophagy with natural products as a potential therapeutic approach for diabetic microangiopathy

As the quality of life improves, the incidence of diabetes mellitus and its microvascular complications (DMC) continues to increase, posing a threat to people's health and wellbeing. Given the limitations of existing treatment, there is an urgent need for novel approaches to prevent and treat DMC. Autophagy, a pivotal mechanism governing metabolic regulation in organisms, facilitates the removal of dysfunctional proteins and organelles, thereby sustaining cellular homeostasis and energy generation. Anomalous states in pancreatic β-cells, podocytes, Müller cells, cardiomyocytes, and Schwann cells in DMC are closely linked to autophagic dysregulation. Natural products have the property of being multi-targeted and can affect autophagy and hence DMC progression in terms of nutrient perception, oxidative stress, endoplasmic reticulum stress, inflammation, and apoptosis. This review consolidates recent advancements in understanding DMC pathogenesis via autophagy and proposes novel perspectives on treating DMC by either stimulating or inhibiting autophagy using natural products.

Targeted inhibition of transforming growth factor-β type I receptor by AZ12601011 improves paraquat poisoning-induced multiple organ fibrosis

Paraquat (PQ) causes fatal poisoning that leads to systemic multiple organ fibrosis, and transforming growth factor (TGF)-β1 plays a critical role in this process. In this study, we aimed to investigate the effects of AZ12601011 (a small molecular inhibitor of TGFβRI) on PQ-induced multiple organ fibrosis. We established a mouse model of PQ in vivo and used PQ-treated lung epithelial cell (A549) and renal tubular epithelial cells (TECs) in vitro. Haematoxylin-eosin and Masson staining revealed that AZ12601011 ameliorated pulmonary, hepatic, and renal fibrosis, consistent with the decrease in the levels of fibrotic indicators, alpha-smooth muscle actin (α-SMA) and collagen-1, in the lungs and kidneys of PQ-treated mice. In vitro data showed that AZ12601011 suppressed the induction of α-SMA and collagen-1 in PQ-treated A549 cells and TECs. In addition, AZ12601011 inhibited the release of inflammatory factors, interleukin (IL)-1β, IL-6, and tumour necrosis factor-α. Mechanistically, TGF-β and TGFβRI levels were significantly upregulated in the lungs and kidneys of PQ-treated mice. Cellular thermal shift assay and western blotting revealed that AZ12601011 directly bound with TGFβRI and blocked the activation of Smad3 downstream. In conclusion, our findings revealed that AZ12601011 attenuated PQ-induced multiple organ fibrosis by blocking the TGF-β/Smad3 signalling pathway, suggesting its potential for PQ poisoning treatment.

Replacing cholesterol with asiatic acid to prolong circulation and enhance anti-metastatic effects of non-PEGylated liposomes

Cholesterol is an indispensable component of most liposomes, heavily influencing their physical and surface properties. In this study, cholesterol in non-PEGylated liposomes was replaced by its analog, asiatic acid (AA), to generate liposomes with an alternative composition. These AA liposomes are generally smaller and more rigid than conventional liposomes, circulate longer in the body, and accumulate more in primary tumors and lung metastases in vivo. On the other hand, as an active ingredient, AA can decrease TGF-β secretion to inhibit the epithelial-mesenchymal transition (EMT) process, increase the sensitivity of tumor cells to doxorubicin (DOX), and synergize with DOX to enhance the immune response, thus improving their antitumor and anti-metastasis efficiency. Based on this rationale, DOX-loaded AA liposomes were fabricated and tested against triple-negative breast cancer (TNBC). Results showed that compared with conventional liposomes, the DOX-AALip provided approximately 28.4% higher tumor volume reduction with almost no metastatic nodules in the mouse model. Our data demonstrate that AA liposomes are safe, simple, and efficient, and thus in many situations may be used instead of conventional liposomes, having good potential for further clinical translational development.

Role of Caveolin-1 on the molybdenum and cadmium exposure induces pulmonary ferroptosis and fibrosis in the sheep

Molybdenum (Mo) is an essential trace element that exists in all tissues of the human body, but excessive Mo intake has a toxic effect. Cadmium (Cd) is a widely known and harmful heavy metal that exists in the environment. Although studies on Mo and Cd are available, it is still unknown how the combination of Mo and Cd causes pulmonary injury. Forty-eight sheep that were 2 months old were chosen and randomly separated into four groups as follows: Control group, Mo group, Cd group, and Mo + Cd group. The experiment lasted 50 days. The results showed that Mo and/or Cd caused significant pathological damage and oxidative stress in the lungs of sheep. Moreover, Mo and/or Cd exposure could downregulate the expression levels of xCT (SLC7A11 and SLC3A2), GPX4 and FTH-1 and upregulate the expression levels of PTGS2 and NCOA4, which led to iron overload and ferroptosis. Ferroptosis induced Wnt/β-catenin-mediated fibrosis by elevating the expression levels of Caveolin-1 (CAV-1), Wnt 1, Wnt3a, β-catenin (CTNNB1), TCF4, Cyclin D1, mmp7, α-SMA (ACTA2), Collagen 1 (COL1A1) and Vimentin. These changes were particularly noticeable in the Mo and Cd combination group. In conclusion, these data demonstrated that Mo and/or Cd exposure led to lung ferroptosis by inhibiting the SLC7A11/GSH/GPX4 axis, which in turn increases CAV-1 expression and subsequently activates the Wnt/β-catenin pathway, leading to fibrosis in sheep lungs.

Asiatic acid alleviates cisplatin-induced renal fibrosis in tumor-bearing mice by improving the TFEB-mediated autophagy-lysosome pathway

Nephrotoxicity is a major side effect of cisplatin treatment of solid tumors in the clinical setting. Long-term low-dose cisplatin administration causes renal fibrosis and inflammation. However, few specific medicines with clinical application value have been developed to reduce or treat the nephrotoxic side effects of cisplatin without affecting its tumor-killing effect. The present study analyzed the potential reno-protective effect and mechanism of asiatic acid (AA) in long-term cisplatin-treated nude mice suffering from tumors. AA treatment significantly attenuated renal injury, inflammation, and fibrosis induced by long-term cisplatin injection in tumor-bearing mice. AA administration notably suppressed tubular necroptosis and improved the autophagy-lysosome pathway disruption caused by chronic cisplatin treatment in tumor-transplanted nude mice and HK-2 cells. AA promoted transcription factor EB (TFEB)-mediated lysosome biogenesis and reduced the accumulation of damaged lysosomes, resulting in enhanced autophagy flux. Mechanistically, AA increased TFEB expression by rebalancing Smad7/Smad3, whereas siRNA inhibition of Smad7 or TFEB abolished the effect of AA on autophagy flux in HK-2 cells. In addition, AA treatment did not weaken, but actually enhanced the anti-tumor effect of cisplatin, as evidenced by the promoted tumor apoptosis and inhibited proliferation in nude mice. In summary, AA alleviates cisplatin-induced renal fibrosis in tumor-bearing mice by improving the TFEB-mediated autophagy-lysosome pathway.

Biochanin A Ameliorates Nephropathy in High-Fat Diet/Streptozotocin-Induced Diabetic Rats: Effects on NF-kB/NLRP3 Axis, Pyroptosis, and Fibrosis

Nephropathy is the most prevalent microvascular disorder in diabetes mellitus. Oxidative stress and inflammatory cascade provoked by the persistent hyperglycemic milieu play integral roles in the aggravation of renal injury and fibrosis. We explored the impact of biochanin A (BCA), an isoflavonoid, on the inflammatory response, nod-like receptor protein 3 (NLRP3) inflammasome activation, oxidative stress, and fibrosis in diabetic kidneys. A high-fat-diet/streptozotocin (HFD/STZ)-induced experimental model of diabetic nephropathy (DN) was established in Sprague Dawley rats, and in vitro studies were performed in high-glucose-induced renal tubular epithelial (NRK-52E) cells. Persistent hyperglycemia in diabetic rats was manifested by perturbation of renal function, marked histological alterations, and oxidative and inflammatory renal damage. Therapeutic intervention of BCA mitigated histological changes, improved renal function and antioxidant capacity, and suppressed phosphorylation of nuclear factor-kappa B (NF-κB) and nuclear factor-kappa B inhibitor alpha (IκBα) proteins. Our in vitro data reveal excessive superoxide generation, apoptosis, and altered mitochondrial membrane potential in NRK-52E cells that were cultured in a high-glucose (HG) environment were subsided by BCA intervention. Meanwhile, the upregulated expressions of NLRP3 and its associated proteins, the pyroptosis-indicative protein gasdermin-D (GSDMD) in the kidneys, and HG-stimulated NRK-52E cells were significantly ameliorated by BCA treatment. Additionally, BCA blunted transforming growth factor (TGF)-β/Smad signaling and production of collagen I, collagen III, fibronectin, and alfa-smooth muscle actin (α-SMA) in diabetic kidneys. Our results indicate the plausible role of BCA in attenuating DN, presumably through modulation of the apoptotic cascade in renal tubular epithelial cells and the NF-κB/NLRP3 axis.

Asiatic acid improves insulin secretion of cells in type 2 diabetes through TNF-/Mfn2 pathway

OBJECTIVES

To investigate the effects and molecular mechanisms of asiatic acid on β-cell function in type 2 diabetes mellitus (T2DM).

METHODS

The T2DM model was established by high fat diet and streptozotocin injection in ICR mice, and the effects of asiatic acid on glucose regulation were investigated in model mice. The islets were isolated from palmitic acid-treated diabetic mice. ELISA was used to detect the glucose-stimulated insulin secretion, tumor necrosis factor (TNF)-α and interleukin (IL)-6. ATP assay was applied to measure ATP production, and Western blotting was used to detect protein expression of mature β cell marker urocortin (Ucn) 3 and mitofusin (Mfn) 2. The regulatory effects of asiatic acid on glucose-stimulated insulin secretion (GSIS) and Ucn3 expression were also investigated after siRNA interference with Mfn2 or treatment with TNF-α.

RESULTS

Asiatic acid with the dose of 25 mg·kg－1·d－1 had the best glycemic control in T2DM mice and improved the homeostasis model assessment β index. Asiatic acid increased the expression of Mfn2 and Ucn3 protein and improved the GSIS function of diabetic β cells in vitro and in vivo (both P<0.05). Moreover, it improved the ATP production of islets of T2DM mice in vitro (P<0.05). Interfering Mfn2 with siRNA blocked the up-regulation of Ucn3 and GSIS induced by asiatic acid. Asiatic acid inhibited islet TNF-α content and increased Mfn2 and Ucn3 protein expression inhibited by TNF-α.

CONCLUSIONS

Asiatic acid improves β cell insulin secretion function in T2DM mice by maintaining the β cell maturity, which may be related to the TNF-α/Mfn2 pathway.

Asiatic acid attenuates tubular injury in diabetic kidney disease by regulating mitochondrial dynamics via the Nrf-2 pathway

BACKGROUND

Mitochondrial dynamics plays a crucial role in tubular injury in diabetic kidney disease (DKD). Asiatic acid (AA) has demonstrated renal protective effects in DKD; however, its therapeutic effect on tubular injury in DKD remains unclear.

PURPOSE

This study aimed to verify the effects of AA on tubular injury in DKD and underlying mechanisms.

STUDY DESIGN

In the present study, the effects of AA on tubular injury were assessed in rats with streptozotocin-induced diabetes and advanced glycation end products (AGEs)-stimulated HK-2 cells models.

METHODS

After oral administration with or without AA for ten weeks, body weight and levels of fast blood glucose, serum creatinine (sCr), blood urea nitrogen (BUN), urinary albumin, and kidney injury molecule-1 (KIM-1) were detected. Histological analysis was performed to evaluate the renal function of rats. Moreover, the expression of proteins associated with the Nrf-2 pathway and mitochondrial dynamics was analyzed. AGEs-stimulated HK-2 cells were examined to evaluate the tubular protection and the mechanism of AA in vitro.

RESULTS

AA remarkably decreased albumin levels, KIM-1 levels in urine, and serum Cr, and BUN levels. In addition, AA prevented tubular injury and mitochondrial injury by regulating the Nrf-2 pathway and mitochondrial dynamics. Furthermore, the effects of AA on mitochondrial dynamics and tubular protection were eliminated after treatment with ML385 (Nrf2 inhibitor).

CONCLUSION

These findings suggested that AA might be developed as a potential candidate for the treatment of tubular injury in DKD, and its effects are potentially mediated via the regulation of the Nrf-2 pathway and mitochondrial dynamics.

Chinese herbal medicine and its active compounds in attenuating renal injury via regulating autophagy in diabetic kidney disease

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease worldwide, and there is a lack of effective treatment strategies. Autophagy is a highly conserved lysosomal degradation process that maintains homeostasis and energy balance by removing protein aggregates and damaged organelles. Increasing evidence suggests that dysregulated autophagy may contribute to glomerular and tubulointerstitial lesions in the kidney under diabetic conditions. Emerging studies have shown that Chinese herbal medicine and its active compounds may ameliorate diabetic kidney injury by regulating autophagy. In this review, we summarize that dysregulation or insufficiency of autophagy in renal cells, including podocytes, glomerular mesangial cells, and proximal tubular epithelial cells, is a key mechanism for the development of DKD, and focus on the protective effects of Chinese herbal medicine and its active compounds. Moreover, we systematically reviewed the mechanism of autophagy in DKD regulated by Chinese herb compound preparations, single herb and active compounds, so as to provide new drug candidates for clinical treatment of DKD. Finally, we also reviewed the candidate targets of Chinese herbal medicine regulating autophagy for DKD. Therefore, further research on Chinese herbal medicine with autophagy regulation and their targets is of great significance for the realization of new targeted therapies for DKD.

New triterpenoids from the Cyclocarya paliurus (Batalin) Iljinskaja and their anti-fibrotic activity

Cyclocarya paliurus, a Chinese herbal medicine and new food resource, contains a triterpenic-acid-rich extract that demonstrated ameliorative effect on diabetic nephropathy (DN). A more in-depth discovery of functional components led to the isolation of seven new triterpenoids including two pentacyclic triterpenes, 1α,2α,3β,23-tetrahydroxyolean-12-en-28-oic acid and 2α,3β,22α-tirhydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranoside, and five tetracyclic triterpenoid glycosides (cypaliurusides N-R), together with twelve known compounds from the leaves of C. paliurus. Their structures were determined using a comprehensive analysis of chemical and spectroscopic data. Partial compounds were assessed for anti-fibrotic activities in high-glucose and TGF-β1 induced HK-2 cells. Compound 16 remarkably decreased the level of fibronectin with an inhibition rate of 37.1%. Furthermore, 16 effectively alleviated the epithelial-mesenchymal transformation (EMT) process by upregulating E-cadherin expression and downregulating α-SMA expression, and it significantly decreased the level of the transcriptional inhibitors (Snail and Twist) of E-cadherin. The discovery of anti-fibrotic compounds from C. paliurus provides the potential utilization and functional candidates for the DN prevention.