Curcumin attenuates renal interstitial fibrosis by regulating autophagy and retaining mitochondrial function in unilateral ureteral obstruction rats

The PI3K/Akt pathway: a target for curcumin's therapeutic effects

Purpose

The purpose of this review study is to investigate the effect of curcumin on the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway in various diseases. Curcumin, the main compound found in turmeric, has attracted a lot of attention for its diverse pharmacological properties. These properties have increased the therapeutic potential of curcumin in chronic diseases such as cardiovascular disease, Type 2 diabetes, obesity, non-alcoholic fatty liver disease, kidney disease, and neurodegenerative diseases. One of the main mechanisms of the effect of curcumin on health is its ability to modulate the PI3K/Akt signaling pathway. This pathway plays an important role in regulating vital cellular processes such as growth, cell survival, metabolism, and apoptosis. Disruption of the PI3K/Akt signaling pathway is associated with the incidence of several diseases.

Methods

Electronic databases including PubMed, Google Scholar, and Scopus were searched with the keywords "phosphoinositide 3-kinase" AND "protein kinase B "AND "curcumin" in the title/abstract. Also, following keywords "non-alcoholic fatty liver disease" AND "diabetes" AND "obesity" AND "kidney disease" and "neurodegenerative diseases" was searched in the whole text.

Results

Research indicates that curcumin offers potential benefits for several health conditions. Studies have shown it can help regulate blood sugar, reduce inflammation, and protect the heart, kidneys, and brain.

Conclusion

This protective effect is partially achieved by regulating the PI3K-Akt survival pathway, which helps improve metabolic disorders and oxidative stress. By examining how curcumin affects this vital cell pathway, researchers can discover new treatment strategies for a range of diseases.

Chronic changes developing in the hydronephrotic and contralateral kidneys during unilateral ureteral obstruction in rats

BACKGROUND

Animal models of chronic kidney disease are important experimental tools used to validate new mechanisms and potential innovations, as well as to investigate therapeutic interventions before clinical trials in humans. This study aimed to determine the chronic changes occurring in the obstructed kidneys (OK) and the contralateral (CL) kidneys in unilateral ureteral obstruction (UUO) in rats.

METHODS AND RESULTS

In the study, three groups (n:6) were formed. It was observed that dilated tubules decreased at 28 days compared to 14 days, while mononuclear cell infiltration and fibrosis increased. In the CL kidneys, glutathione (GSH) was lower compared to the control group (CG) at 14 days; at 28 days, malondialdehyde (MDA) was elevated, and GSH and catalase (CAT) levels were reduced. Nuclear factor erythroid 2-related factor 2 (NRF-2) protein expression was lower in the OK compared to the CL kidneys at both 14 and 28 days. NRF-2 gene expression was lower in the OK only at 28 days compared to the CG. However, in the CL kidneys, NRF-2 gene expression was higher at both 14 and 28 days compared to the CG. Cyclooxygenase-2 (COX-2) protein levels showed a significant increase in both the OK and CL kidneys at 14 days. COX-2 gene expression increased in the OK at 14 days compared to the CG. BAX protein levels were lower in the OK at 28 days compared to both the CG and CL kidneys. BCL-2 protein levels were lower in the OK compared to the CL kidneys at both 14 and 28 days.

CONCLUSION

This study has identified changes in both the OK and CL kidneys, providing significant data for potential therapeutic, supportive, or protective research aimed at treating these kidneys.

Research dynamics and drug treatment of renal fibrosis from a mitochondrial perspective: a historical text data analysis based on bibliometrics

Renal fibrosis (RF) represents a significant public health challenge, necessitating the urgent identification of effective and safe therapeutic agents. Mitochondrial-targeted strategies have demonstrated considerable promise in restoring renal function and mitigating fibrosis. This study aims to examine the evolution of research and therapeutic interventions for RF from a mitochondrial perspective through bibliometric analysis. Literature retrieval was primarily conducted using the Web of Science Core Collection. Visual analysis was performed utilizing the Bibliometrix package (R- 4.4.2), CiteSpace 6.3.R1, and VOSviewer 1.6.19. A total of 819 documents were included for analysis. Significant contributions were made by researchers from China and the USA, with Nanjing Medical University leading in publication volume. Zhang Aihua and Huang Songming emerge as key scholars in the field, while the International Journal of Molecular Sciences is the journal with the highest publication output. Key research themes include oxidative stress, expression, injury, activation, mechanisms, and mitochondrial dysfunction. Mitochondrial-targeted approaches for treating RF can be categorized into six main strategies: mitochondrial biogenesis regulators, mitochondrial dynamics modulators, mitophagy inducers, oxidative stress regulators, NLRP3 inhibitors, and other mitochondrial-targeted therapeutic approaches. This study comprehensively examines the current state of RF research from a mitochondrial standpoint, summarizing key drugs and potential mechanisms of mitochondrial regulation. The findings aim to enhance scholarly understanding of the ongoing research trends and provide valuable insights for the development of targeted therapeutic agents.

Inhibiting NLRP3 enhances cellular autophagy induced by outer membrane vesicles from Pseudomonas aeruginosa

The bacterium Pseudomonas aeruginosa is able to invade lung epithelial cells and survive intracellularly. During this process, it secretes outer membrane vesicles (OMVs), however, it is currently unclear how OMVs from P. aeruginosa (PA-OMVs) affect lung epithelial cells and their impact on oxidative stress, autophagy, and other physiological activities of lung epithelial cells. In this study, we found that PA-OMVs activated oxidative stress and autophagy in cells. We demonstrated that the NLRP3 (NLR family, pyrin domain containing 3) inhibitor MCC950 can enhance autophagy induced by PA-OMVs. The main function of NLRP3 is related to the body's immune response and inflammation regulation. MCC950 is the most common inhibitor of NLRP3. Additionally, we showed that PA-OMVs not only enhanced the expression of AMP-activated protein kinase, a key regulator of cellular energy homeostasis, and reactive oxygen species, which play a crucial role in cellular signaling and oxidative stress, but also significantly enhanced the expression of NLRP3. Inhibiting the expression of NLRP3 further enhanced the process of PA-OMVs induced autophagy. These results demonstrate that PA-OMVs activate both autophagy and the NLRP3 inflammasome, with NLRP3 suppressing autophagy to a certain extent, hoping to provide broad ideas for the future applications of PA-OMVs.IMPORTANCEThe discovery that lung epithelial cells exposed to outer membrane vesicles from Pseudomonas aeruginosa (PA-OMVs) activate cellular autophagy and induce protective immunity is significant. Specifically, the addition of an NLRP3 inhibitor, MCC950, has been found to decrease NLRP3 targets while simultaneously enhancing the autophagy activity induced by PA-OMVs. This finding unveils a novel theoretical framework for the development of PA-OMVs vaccines, highlighting new targets for enhancing the body's anti-infective responses. By elucidating the mechanisms through which PA-OMVs trigger autophagy and bolster immune defenses, this research opens avenues for innovative vaccine design strategies aimed at combatting infections effectively.

Sulforaphane Restores Mitochondrial β-Oxidation and Reduces Renal Lipid Accumulation in a Model of Releasing Unilateral Ureteral Obstruction

Obstructive nephropathy (ON), characterized by urine flow disruption, can induce chronic kidney disease (CKD). Although the release of the obstruction is performed as the primary intervention, renal pathology often persists and progresses. Accordingly, the murine model of releasing unilateral ureteral obstruction (RUUO) is valuable for investigating the molecular events underlying renal damage after obstruction release. Remarkably, after RUUO, disturbances such as oxidative stress, inflammation, lipid accumulation, and fibrosis continue to increase. Mitochondrial dysfunction contributes to fibrosis in the UUO model, but its role in RUUO remains unclear. Additionally, the impact of using antioxidants to restore mitochondrial function and prevent renal fibrosis in RUUO has not been determined. This study aimed to determine the therapeutic effect of pre-administering the antioxidant sulforaphane (SFN) in the RUUO model. SFN was administered 1 day before RUUO to evaluate mitochondrial biogenesis, fatty acids (FA) metabolism, bioenergetics, dynamics, and mitophagy/autophagy mechanisms in the kidney. Our data demonstrated that SFN enhanced mitochondrial biogenesis and reestablished mitochondrial oxygen consumption and β-oxidation. These effects collectively reduced lipid accumulation and normalized mitochondrial dynamics, mitophagy, and autophagy, thereby mitigating fibrosis after obstruction. Our findings suggest that SFN holds promise as a potential therapeutic agent in ON-induced CKD progression in RUUO and opens new avenues in studying antioxidant molecules to treat this disease.

Exploring the health benefits of food bioactive compounds from a perspective of NLRP3 inflammasome activation: an insight review

The food industry has been focusing on food bioactive compounds with multiple physiological and immunological properties that benefit human health. These bioactive compounds, including polyphenols, flavonoids, and terpenoids, have great potential to limit inflammatory responses especially NLRP3 inflammasome activation, which is a key innate immune platform for inflammation. Current studies have revealed numerous food bioactive compounds with promising activities for unraveling immune metabolic disorders and excessive inflammatory responses by directly and indirectly regulating the NLRP3 inflammasome activation. This review explores the food hazards, including microbial and abiotic factors, that may trigger NLRP3-mediated illnesses and inflammation. It also highlights bioactive compounds in food that can suppress NLRP3 inflammasome activation through various mechanisms, linking its activation and inhibition to different pathways. Especially, this review provided further insight into NLRP3-related targets where food bioactive compounds can interact to block the NLRP3 inflammasome activation process, as well as mechanisms on how these compounds facilitate inactivation processes.

The Potential of Naturally Derived Compounds for Treating Chronic Kidney Disease: A Review of Autophagy and Cellular Senescence

Chronic kidney disease (CKD) is characterized by irreversible progressive worsening of kidney function leading to kidney failure. CKD is viewed as a clinical model of premature aging and to date, there is no treatment to reverse kidney damage. The well-established treatment for CKD aims to control factors that may aggravate kidney progression and to provide kidney protection effects to delay the progression of kidney disease. As an alternative, Traditional Chinese Medicine (TCM) has been shown to have fewer adverse effects for CKD patients. However, there is a lack of clinical and molecular studies investigating the mechanisms by which natural products used in TCM can improve CKD. In recent years, autophagy and cellular senescence have been identified as key contributors to aging and age-related diseases. Exploring the potential of natural products in TCM to target these processes in CKD patients could slow disease progression. A better understanding of the characteristics of these natural products and their effects on autophagy and cellular senescence through clinical studies, coupled with the use of these products as complementary therapy alongside mainstream treatment, may maximize therapeutic benefits and minimize adverse effects for CKD patients. While promising, there is currently a lack of thorough research on the potential synergistic effects of these natural products. This review examines the use of natural products in TCM as an alternative treatment for CKD and discusses their active ingredients in terms of renoprotection, autophagy, and cellular senescence.

Therapy Targeted to the NLRP3 Inflammasome in Chronic Kidney Disease

Background

The NLRP3 inflammasome is a cytoplasmic polymeric protein complex composed of the cytoplasmic sensor NLRP3, the apoptosis-related spot-like protein ASC, and the inflammatory protease caspase-1. NLRP3 activates and releases IL-1β through classical pathways, and IL-18 mediates inflammation and activates gasdermin-D protein to induce cellular pyroptosis. Numerous studies have also emphasized the non-classical pathway activated by the NLRP3 inflammasome in chronic kidney disease (CKD) and the inflammasome-independent function of NLRP3.

Summary

The NLRP3-targeting inflammasome and its associated pathways have thus been widely studied in models of CKD treatment, but no drug that targets NLRP3 has thus far been approved for the treatment of CKD.

Key Messages

We herein reviewed the current interventional methods for targeting the NLRP3 inflammasome in various CKD models, analyzed their underlying mechanisms of action, classified and compared them, and discussed the advantages and follow-up directions of various interventional methods. This review therefore provides novel ideas and a reference for the development of targeted NLRP3-inflammasome therapy in CKD.

Therapeutic approaches and novel antifibrotic agents in renal fibrosis: A comprehensive review

Renal fibrosis (RF) is one of the underlying pathological conditions leading to progressive loss of renal function and end-stage renal disease (ESRD). Over the years, various therapeutic approaches have been explored to combat RF and prevent ESRD. Despite significant advances in understanding the underlying molecular mechanism(s), effective therapeutic interventions for RF are limited. Current therapeutic strategies primarily target these underlying mechanisms to halt or reverse fibrotic progression. Inhibition of transforming growth factor-β (TGF-β) signaling, a pivotal mediator of RF has emerged as a central strategy to manage RF. Small molecules, peptides, and monoclonal antibodies that target TGF-β receptors or downstream effectors have demonstrated potential in preclinical models. Modulating the renin-angiotensin system and targeting the endothelin system also provide established approaches for controlling fibrosis-related hemodynamic changes. Complementary to pharmacological strategies, lifestyle modifications, and dietary interventions contribute to holistic management. This comprehensive review aims to summarize the underlying mechanisms of RF and provide an overview of the therapeutic strategies and novel antifibrotic agents that hold promise in its treatment.

Role of mitochondria in pathogenesis and therapy of renal fibrosis

Renal fibrosis, specifically tubulointerstitial fibrosis, represents the predominant pathological consequence observed in the context of progressive chronic kidney conditions. The pathogenesis of renal fibrosis encompasses a multifaceted interplay of mechanisms, including but not limited to interstitial fibroblast proliferation, activation, augmented production of extracellular matrix (ECM) components, and impaired ECM degradation. Notably, mitochondria, the intracellular organelles responsible for orchestrating biological oxidation processes in mammalian cells, assume a pivotal role within this intricate milieu. Mitochondrial dysfunction, when manifest, can incite a cascade of events, including inflammatory responses, perturbed mitochondrial autophagy, and associated processes, ultimately culminating in the genesis of renal fibrosis. This comprehensive review endeavors to furnish an exegesis of mitochondrial pathophysiology and biogenesis, elucidating the precise mechanisms through which mitochondrial aberrations contribute to the onset and progression of renal fibrosis. We explored how mitochondrial dysfunction, mitochondrial cytopathy and mitochondrial autophagy mediate ECM deposition and renal fibrosis from a multicellular perspective of mesangial cells, endothelial cells, podocytes, macrophages and fibroblasts. Furthermore, it succinctly encapsulates the most recent advancements in the realm of mitochondrial-targeted therapeutic strategies aimed at mitigating renal fibrosis.

Fluorofenidone attenuates renal fibrosis by inhibiting lysosomal cathepsin‑mediated NLRP3 inflammasome activation

Currently, no antifibrotic drug in clinical use can effectively treat renal fibrosis. Fluorofenidone (AKFPD), a novel pyridone agent, significantly reduces renal fibrosis by inhibiting the activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome; however, the underlying mechanism of this inhibition is not fully understood. The present study aimed to reveal the molecular mechanism underlying the suppression of NLRP3 inflammasome activation by AKFPD. It investigated the effect of AKFPD on NLRP3 activation and lysosomal cathepsins in a unilateral ureteral obstruction (UUO) rat model, and hypoxia/reoxygenation (H/R)-treated HK-2 cells and murine peritoneal-derived macrophages (PDMs) stimulated with lipopolysaccharide (LPS) and ATP. The results confirmed that AKFPD suppressed renal interstitial fibrosis and inflammation by inhibiting NLRP3 inflammasome activation in UUO rat kidney tissues. In addition, AKFPD reduced the production of activated caspase-1 and maturation of IL-1β by suppressing NLRP3 inflammasome activation in H/R-treated HK-2 cells and murine PDMs stimulated with LPS and ATP. AKFPD also decreased the activities of cathepsins B, L and S both in vivo and in vitro. Notably, AKFPD downregulated cathepsin B expression and NLRP3 colocalization in the cytoplasm after lysosomal disruptions. Overall, the results suggested that AKFPD attenuates renal fibrosis by inhibiting lysosomal cathepsin-mediated activation of the NLRP3 inflammasome.

Natural products in traditional Chinese medicine: molecular mechanisms and therapeutic targets of renal fibrosis and state-of-the-art drug delivery systems

Renal fibrosis (RF) is the end stage of several chronic kidney diseases. Its series of changes include excessive accumulation of extracellular matrix, epithelial-mesenchymal transition (EMT) of renal tubular cells, fibroblast activation, immune cell infiltration, and renal cell apoptosis. RF can eventually lead to renal dysfunction or even renal failure. A large body of evidence suggests that natural products in traditional Chinese medicine (TCM) have great potential for treating RF. In this article, we first describe the recent advances in RF treatment by several natural products and clarify their mechanisms of action. They can ameliorate the RF disease phenotype, which includes apoptosis, endoplasmic reticulum stress, and EMT, by affecting relevant signaling pathways and molecular targets, thereby delaying or reversing fibrosis. We also present the roles of nanodrug delivery systems, which have been explored to address the drawback of low oral bioavailability of natural products. This may provide new ideas for using natural products for RF treatment. Finally, we provide new insights into the clinical prospects of herbal natural products.

The progression of obstructive renal fibrosis in rats is regulated by ADAMTS18 gene methylation in the embryonic kidney through the AKT/Notch pathway

This study aimed to explore the mechanism by which postembryonic renal ADAMTS18 methylation influences obstructive renal fibrosis in rats. After exposure to transforming growth factor (TGF)-β1 during the embryonic period, analysis of postembryonic renal ADAMTS18 methylation and expression levels was conducted. Histological analysis was performed to assess embryonic kidney lesions and damage. Western blot analysis was used to determine the expression of renal fibrosis markers. Rats with ureteral obstruction and a healthy control group were selected. The methylation levels of ADAMTS18 in the different groups were analyzed. Western blot analysis and immunohistochemistry were performed to analyze the expression of renal fibrosis markers, and kidney-related indicators were measured. Treatment with TGF-β1 resulted in abnormal development of the postembryonic kidney, which was characterized by rough kidney surfaces with mild depressions and irregularities on the outer surface. TGF-β1 treatment significantly promoted ADAMTS18 methylation and activated the protein kinase B (AKT)/Notch pathway. Ureteral obstruction was induced to establish a renal hydronephrosis model, which led to renal fibrotic injury in newborn rats. Overexpression of the ADAMTS18 gene alleviated renal fibrosis. The western blot results showed that compared to that in the control group, the expression of renal fibrosis markers was significantly decreased after ADAMTS18 overexpression, and there was a thicker renal parenchymal tissue layer and significantly reduced p-AKT/AKT and Notch1 levels. TGF-β1 can induce ADAMTS18 gene methylation in the postembryonic kidney, and the resulting downregulation of ADAMTS18 expression has long-term effects on kidney development, potentially leading to increased susceptibility to obstructive renal fibrosis. This mechanism may involve activation of the AKT/Notch pathway. Reversing ADAMTS18 gene methylation may reverse this process.

The Protective Effects of Curcumin against Renal Toxicity

Curcumin is a naturally polyphenolic compound used for hepatoprotective, thrombosuppressive, neuroprotective, cardioprotective, antineoplastic, antiproliferative, hypoglycemic, and antiarthritic effects. Kidney disease is a major public health problem associated with severe clinical complications worldwide. The protective effects of curcumin against nephrotoxicity have been evaluated in several experimental models. In this review, we discussed how curcumin exerts its protective effect against renal toxicity and also illustrated the mechanisms of action such as anti-inflammatory, antioxidant, regulating cell death, and anti-fibrotic. This provides new perspectives and directions for the clinical guidance and molecular mechanisms for the treatment of renal diseases by curcumin.

Curcumin Protects Human Dermal Fibroblasts Exposed to Hydrogen Peroxide by Regulating Autophagy Level and Reactive Oxygen Species Generation

Curcumin is getting more and more attention in wound healing and scar prevention because of its wide range of pharmacological effects, such as anti-inflammation, antioxidant, and anti-fibrosis. The activity of fibroblasts suffering from oxidative stress is reduced, affecting wound repair. In this study, we investigated whether curcumin treatment (10 μM, 24 hours) had protective effects on human dermal fibroblasts (HDFs) exposed to hydrogen peroxide (H2O2, 300 μM, 12 hours). We found that curcumin alleviated H2O2-induced accumulation of reactive oxygen species (ROS, the fold change relative to the untreated control was 1.75 [SD ± 0.21] vs 5.23 [SD ± 0.51], P < .001) and improved the expression and activities of antioxidant enzymes superoxide dismutase 1 (66.61 U [SD ± 7.47] vs 46.39 U [SD ± 6.82]/106 cells, P < .05) and catalase (9.77 U [SD ± 1.82] vs 4.61 U [SD ± 0.94]/106 cells, P < .01), accompanied with increased cell proliferation and migration but decreased senescence. In addition, we found that curcumin reduced the inhibition of autophagy by H2O2, as manifested in the increased autophagic vacuoles (P < .05) and higher expression of autophagy-related proteins including phosphoinositide-3-kinase class III (P < .001), light chain 3 form II (P < .001), and Beclin1 (P < .01). However, intracellular redox status deteriorated again and curcumin's protection effects were partially canceled after autophagy was inhibited by 3-methyladenine pretreatment. These data suggest that rescue of HDFs from oxidative damage by curcumin may related to the regulation of autophagy levels and ROS generation.

Global research trends in unilateral ureteral obstruction-induced renal fibrosis: A bibliometric and visualized study

BACKGROUND

Renal fibrosis is considered the pathway from almost all chronic kidney diseases (CKD) to end-stage renal diseases. The unilateral ureteral obstruction (UUO) model is a well-established experimental animal model to simulate renal fibrosis associated with obstructive nephropathy in an accelerated manner. In this study, in order to understand the development trends of research on UUO-induced renal fibrosis between 2005 and 2022 and predict prospects, we conducted a comprehensive bibliometric and visualized study using Web of Science (WoS).

METHODS

The articles regarding UUO-induced renal fibrosis were culled from the "Core Collection" of the WoS database. VOSviewer software and the R-Bibliometrix Package were used in visual analysis of countries/regions, journals, authors, keywords, institutions, and highly cited articles in this field.

RESULTS

The number of articles regarding UUO-induced renal fibrosis has obviously increased annually. China had the largest number of publications in this field. The most frequently used keywords were "inflammation," "transforming growth factor-beta1," "oxigative stress," "smad3," "beta-catenin," and "autophagy." Am J Physiol-Renal was the leading journal. The most highly influential documents were published by Higgins DF and his colleagues, with 46 local citations and 749 global citations. The leading institution was Nanjing Medical University. Furthermore, Zhang Y. was the author who contributed most to this field.

CONCLUSION

Our results suggest that the molecular mechanism of UUO-induced renal fibrosis remains a research hot topic, especially on the inflammatory response and oxidative stress, and international cooperation is expected to expand and deepen in the future.

Autophagy in Cell Survival and Death

Autophagy is a degradative process to remove damaged or unnecessary cellular components, and it has been implicated in many biological processes during cell survival and death [...].

Heidihuangwan alleviates renal fibrosis in rats with 5/6 nephrectomy by inhibiting autophagy

Renal fibrosis is a common pathway for the progression of various chronic kidney diseases (CKD), and the formation and deterioration will eventually lead to end-stage renal failure, which brings a heavy medical burden to the world. HeidihuangWan (HDHW) is a herbal formulation with stable and reliable clinical efficacy in the treatment of renal fibrosis. However, the mechanism of HDHW in treating renal fibrosis is not clear. In this study, we aimed to investigate the mechanism of HDHW to improve renal fibrosis. Wistar rats were randomly divided into the normal control group, 5/6 Nephrectomy group, astragaloside IV (AS-IV) group, HDHW group, and HDHW + IGF-1R inhibitor (JB1) group. Except for the normal control group, the rat renal fibrosis model was established by 5/6 nephrectomy and intervened with drugs for 8 weeks. Blood samples were collected to evaluate renal function. Hematoxylin-Eosin (HE), Periodic Acid-Schiff (PAS), Modified Masson’s Trichrome (Masson) staining were used to evaluate the pathological renal injury, and immunohistochemistry and Western blotting were used to detect the protein expression of renal tissue. The results showed that HDHW was effective in improving renal function and reducing renal pathological damage. HDHW down-regulated the levels of fibrosis marker proteins, including α-smooth muscle actin (α-SMA), vimentin, and transforming growth factors–β(TGF-β), which in turn reduced renal fibrosis. Further studies showed that HDHW down-regulated the expression of autophagy-related proteins Beclin1 and LC3II, indicating that HDHW inhibited autophagy. In addition, we examined the activity of the class I phosphatidylinositol-3 kinase (PI3K)/serine-threonine kinase (Akt)/mTOR pathway, an important signaling pathway regulating autophagy, and the level of insulin-like growth factor 1 (IGF-1), an upstream activator of PI3K/Akt/mTOR. HDHW upregulated the expression of IGF-1 and activated the PI3K/Akt/mTOR pathway, which may be a vital pathway for its inhibition of autophagy. Application of insulin-like growth factor 1 receptor (IGF-1R) inhibitor further confirmed that the regulation of autophagy and renal fibrosis by HDHW was associated with IGF-1-mediated activation of the PI3K/Akt/mTOR pathway. In conclusion, our study showed that HDHW inhibited autophagy by upregulating IGF-1 expression, promoting the binding of IGF-1 to IGF-1R, and activating the PI3K/Akt/mTOR signaling pathway, thereby reducing renal fibrosis and protecting renal function. This study provides support for the application and further study of HDHW.

Natural products: potential drugs for the treatment of renal fibrosis

With the increasing prevalence and mortality, chronic kidney disease (CKD) has become a world public health problem. As the primary pathological manifestation in CKD, renal fibrosis is often used as a critical target for the treatment of CKD and inhibits the progression of CKD to end-stage renal disease (ESRD). As a potential drug, natural products have been confirmed to have the potential as a routine or supplementary therapy for chronic kidney disease, which may target renal fibrosis and act through various pharmacological activities such as anti-inflammatory and anti-oxidation of natural products. This article briefly introduces the pathological mechanism of renal fibrosis and systematically summarizes the latest research on the treatment of renal fibrosis with natural products of Chinese herbal medicines.

The Effect of Polyphenols on Kidney Disease: Targeting Mitochondria

Mitochondrial function, including oxidative phosphorylation (OXPHOS), mitochondrial biogenesis, and mitochondria dynamics, are essential for the maintenance of renal health. Through modulation of mitochondrial function, the kidneys are able to sustain or recover acute kidney injury (AKI), chronic kidney disease (CKD), nephrotoxicity, nephropathy, and ischemia perfusion. Therapeutic improvement in mitochondrial function in the kidneys is related to the regulation of adenosine triphosphate (ATP) production, free radicals scavenging, decline in apoptosis, and inflammation. Dietary antioxidants, notably polyphenols present in fruits, vegetables, and plants, have attracted attention as effective dietary and pharmacological interventions. Considerable evidence shows that polyphenols protect against mitochondrial damage in different experimental models of kidney disease. Mechanistically, polyphenols regulate the mitochondrial redox status, apoptosis, and multiple intercellular signaling pathways. Therefore, this review attempts to focus on the role of polyphenols in the prevention or treatment of kidney disease and explore the molecular mechanisms associated with their pharmacological activity.

Curcumin activation of nuclear factor E2-related factor 2 gene (Nrf2): Prophylactic and therapeutic effect in nonalcoholic steatohepatitis (NASH)

BACKGROUNDS

Modern dietary habits have been associated with Nonalcoholic Steatohepatitis (NASH). Curcumin is a natural herbal found to suppress cellular oxidative states and could be beneficial in NASH. This study investigates the effect of curcumin in an animal model of NASH.

MATERIALS AND METHODS

Fifty rats were allocated into five groups. Control, High Fat Diet (HFD), curcumin prophylactic (CP) and therapeutic (CT) groups. HFD regimen was given for 16 weeks. Curcumin was given along with HFD (prophylactic) or after establishment of the model for two weeks (therapeutic). Livers and blood samples were harvested for histological, biochemical, and molecular studies.

KEY FINDINGS

Livers from HFD groups showed vascular, inflammatory, cellular degenerative and fibrotic changes. The hepatic damage was reflected by the increased serum liver enzymes. HFD groups showed excessive fibrotic change. Interestingly, curcumin administration as prophylactic or therapeutic significantly preserved and/or restored liver structure. This was evidenced by the normalization of the liver enzymes, preservation and/or reversibility of cellular changes and the decrease of the stage of fibrosis. Nuclear factor E2-related factor 2 gene (Nrf2) expression showed no changes in the HFD groups, however it showed upregulation in curcumin treated groups. Thus, the protective and therapeutic effect of curcumin could be induced through upregulation of the Nrf2 gene. Curcumin has a beneficial prophylactic and therapeutic effect that could hinder the development and/or treat NASH in susceptible livers.

SIGNIFICANCE

Curcumin has a beneficial prophylactic and therapeutic effect that could hinder the development and/or treat NASH in susceptible livers.

Exogenous Hydrogen Sulfide Plays an Important Role by Regulating Autophagy in Diabetic-Related Diseases

Autophagy is a vital cell mechanism which plays an important role in many physiological processes including clearing long-lived, accumulated and misfolded proteins, removing damaged organelles and regulating growth and aging. Autophagy also participates in a variety of biological functions, such as development, cell differentiation, resistance to pathogens and nutritional hunger. Recently, autophagy has been reported to be involved in diabetes, but the mechanism is not fully understood. Hydrogen sulfide (H₂S) is a colorless, water-soluble, flammable gas with the typical odor of rotten eggs, which has been known as a highly toxic gas for many years. However, it has been reported recently that H₂S, together with nitric oxide and carbon monoxide, is an important gas signal transduction molecule. H₂S has been reported to play a protective role in many diabetes-related diseases, but the mechanism is not fully clear. Recent studies indicate that H₂S plays an important role by regulating autophagy in many diseases including cancer, tissue fibrosis diseases and glycometabolic diseases; however, the related mechanism has not been fully studied. In this review, we summarize recent research on the role of H₂S in regulating autophagy in diabetic-related diseases to provide references for future related research.