Curcumin reduces the risk of chronic kidney damage in mice with nonalcoholic steatohepatitis by modulating endoplasmic reticulum stress and MAPK signaling

Hepatoprotective and Fat-Accumulation-Reductive Effects of Curcumin on Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Fat accumulation is the hallmark of metabolic dysfunction-associated steatotic liver disease (MASLD). Given the intimidating nature of its treatment, curcumin (CUR) emerges as a potential therapeutic agent due to its proven effectiveness in managing MASLD. This review aimed to evaluate previous reports on the hepatoprotective and fat-accumulation-reductive effects of CUR administration in preventing or treating MASLD. CUR administration can modulate serum liver enzymes and lipid profiles. The fat accumulation of MASLD is the primary cause of oxidative stress and inflammation. By reducing fat accumulation, CUR may attenuate the inflammation and oxidative stress in MASLD. In addition, CUR has been proven to restore the dysfunctional cellular energy metabolism capacity and attenuate fibrogenesis (antifibrotic agent). Their hepatoprotective effects are associated with fat accumulation in MASLD. Lipid metabolism (lipogenesis, lipolysis, and lipophagy) is correlated with their hepatoprotective effects. CUR has prophylactic and therapeutic effects, particularly in early-stage MASLD, primarily when it is used as a fat reducer. It can be considered an excellent natural therapeutic drug for MASLD because it protects the liver and attenuates fat accumulation, especially in the early stage of MASLD development.

Curcumin ameliorates astrocyte inflammation through AXL in cuprizone-induced mice

Curcumin has gained global attention owning to its anti-inflammatory, antioxidant, anticancer, and antimicrobial activities. Curcumin has recently been shown to have well-documented effects on neuroinflammation in multiple sclerosis (MS). Astrocytes, the most widely distributed glial cells in the brain, have a significant influence on the regulation of neuroinflammation in MS. However, it is unknown how curcumin exerts neuroprotective effects in astrocytes. To elucidate the mechanism underlying the effects of curcumin on astrocytes, we explored the effect of curcumin on cuprizone (CPZ)-induced mice in vivo and on primary astrocytes in vitro. In this study, we observed that curcumin significantly ameliorated myelin loss and reduced astrocyte activation in the corpus callosum (CC) region in mice induced with CPZ, and in primary astrocytes stimulated with lipopolysaccharide (LPS). Meanwhile, our research indicated that curcumin may exert neuroprotective effects in CPZ-induced mice by downregulating astrocyte-mediated inflammation by AXL. This study provides new insights into possible targeted therapies for MS.

Trans-cinnamic acid alleviates high-fat diet-induced renal injury via JNK/ERK/P38 MAPK pathway

Obesity-related chronic kidney disease (CKD) poses a significant risk to individuals' health and wellbeing, but the pathological mechanisms and treatment strategies are currently limited. Trans-cinnamic acid (CA) is a key active monomer found in cinnamon bark and is known for its diverse pharmacological activities. However, its effect on obesity-related renal injury remains unknown. In the current study, the in vitro and in vivo experiments were combined to investigate the beneficial effect of CA on renal injury induced by HFD or PA. We found that CA significantly reduced the obesity of zebrafish body and the accumulation of fat in kidney tissues. The histopathological changes and dysfunction induced by HFD were effectively mitigated by CA administration, as evidenced by the detection of Hematoxylin-Eosin straining, NAG activity, creatinine level, and expression of functional-related genes, respectively. Additionally, the in vitro and in vivo findings demonstrated that CA dramatically reduced the oxidative stress, inflammatory, and apoptosis in HFD-induced kidney tissues or PA-treated HEK293T and HK-2 cells. Finally, the results regarding ERK, JNK, and P38 proteins phosphorylation confirmed that CA may alleviate HFD-induced renal injury by inhibiting the phosphorylation of ERK, JNK, and P38 MAPK proteins. This theory was further supported by the results of co-treatment with anisomycin (a JNK activator) or lipopolysaccharide and CA in HEK293T cells. This study proves that CA alleviates the obesity-related CKD probably through inhibition of MAPK signaling pathway.

Network Pharmacology and Metabolomics Reveal Anti-Ferroptotic Effects of Curcumin in Acute Kidney Injury

Introduction

Acute kidney injury (AKI) is linked to high rates of mortality and morbidity worldwide thereby posing a major public health problem. Evidences suggest that ferroptosis is the primary cause of AKI, while inhibition of monoamine oxidase A(MAOA) and 5-hydroxytryptamine were recognized as the defender of ferroptosis. Curcumin (Cur) is a natural polyphenol and the main bioactive compound of Curcuma longa, which has been found nephroprotection in AKI. However, the potential mechanism of Cur in alleviating AKI ferroptosis remains unknown.

Objective

This study aims to investigate the effects of Cur on AKI ferroptosis.

Methods

Folic acid (FA)-induced AKI mouse model and erastin/(rsl-3)-induced HK-2 model were constructed to assess the renoprotection of Cur. The nuclear magnetic resonance (NMR)-based metabolomics coupled network pharmacology approach was used to explore the metabolic regulation and potential targets of Cur. Molecular docking and enzyme activity assay was carried out to evaluate the effects of Cur on MAOA.

Results

Our results showed that in vivo Cur preserved renal functions in AKI mice by lowering levels of serum creatinine, blood urea nitrogen, while in vitro ameliorated the cell viability of HK-2 cells damaged by ferroptosis. Mechanistic studies indicated that Cur protected AKI against ferroptosis via inhibition of MAOA thereby regulating 5-hydroxy-L-tryptophan metabolism.

Conclusion

Our study for the first time clarified that Cur might acts as a MAOA inhibitor and alleviates ferroptosis in AKI mice, laying a scientific foundation for new insights of clinical therapy on AKI.

Natural products derived from traditional Chinese medicines targeting ER stress for the treatment of kidney diseases

Various factors, both internal and external, can disrupt endoplasmic reticulum (ER) homeostasis and increase the burden of protein folding, resulting in ER stress. While short periods of ER stress can help cells return to normal function, excessive or prolonged ER stress triggers a complex signaling network that negatively affects cells. Numerous studies have demonstrated the significant role of ER stress in various kidney diseases, such as immune-related kidney injury, diabetic kidney diseases, renal ischemia reperfusion injury, and renal fibrosis. To date, there is a severe shortage of medications for the treatment of acute and chronic kidney diseases of all causes. Natural products derived from various traditional Chinese medicines (TCM), which are a major source of new drugs, have garnered considerable attention. Recent research has revealed that many natural products have renoprotective effects by targeting ER stress-mediated events, such as apoptosis, oxidative stress, inflammation, autophagy, and epithelial-mesenchymal transition. This article provides a comprehensive review of the current research progress on natural products targeting ER stress for the treatment of kidney diseases.

Curcumin targets CXCL16-mediated podocyte injury and lipid accumulation in diabetic kidney disease treatment

Among the complications of diabetes, diabetic kidney disease (DKD) frequently emerges, typified by the detrimental effects on renal function, manifesting through inflammation, dysregulated lipid metabolism, and harm to podocytes. Existing research underscores the significance of the soluble form of C-X-C chemokine ligand 16 (CXCL16) within the context of renal impairments. However, whether CXCL16 is involved in the pathogenesis of DKD remains elusive. We report that CXCL16 levels in the serum and kidneys of individuals with DKD were elevated and correlated with various lipid parameters. The expression of CXCL16 in human podocytes subjected to high glucose or palmitic acid induction and exogenous CXCL16 administration in these cells were examined. Higher CXCL16 levels were linked to abnormal lipid metabolism. Exogenous CXCL16 administration induced lipid droplets, microfilament disorganization, apoptosis, oxidative stress, and inflammation, inhibited PPAR γ, up-regulated COX2 expression, and inhibited Nrf2 translocation in podocytes. Molecular analysis revealed that Curcumin (Cur), a polyphenolic compound derived from Curcuma longa and an Nrf2 agonist, targets the ATP-binding pocket of CXCL16, inhibiting its kinase activity. Meanwhile, Cur therapy alleviated podocyte injury, lipid accumulation, improved glomerulopathy, and reduced albuminuria. Furthermore, after silencing CXCL16 expression in podocytes using siRNA, the effects of exogenous CXCL16 were nullified, and Cur no longer exhibited any significant impact. Thus, CXCL16 participates in the pathogenesis of DKD. Inhibition of CXCL16 has shown promising results in experimental models, suggesting its beneficial effects in ameliorating DKD.

Salidroside may target PPARα to exert preventive and therapeutic activities on NASH

Background

Salidroside (SDS), a phenylpropanoid glycoside, is an antioxidant component isolated from the traditional Chinese medicine Rhodiola rosea and has multifunctional bioactivities, particularly possessing potent hepatoprotective function. Non-alcoholic steatohepatitis (NASH) is one of the most prevalent chronic liver diseases worldwide, but it still lacks efficient drugs. This study aimed to assess the preventive and therapeutic effects of SDS on NASH and its underlying mechanisms in a mouse model subjected to a methionine- and choline-deficient (MCD) diet.

Methods

C57BL/6J mice were fed an MCD diet to induce NASH. During or after the formation of the MCD-induced NASH model, SDS (24 mg/kg/day) was supplied as a form of diet for 4 weeks. The histopathological changes were evaluated by H&E staining. Oil Red O staining and Sirius Red staining were used to quantitatively determine the lipid accumulation and collagen fibers in the liver. Serum lipid and liver enzyme levels were measured. The morphology of autophagic vesicles and autophagosomes was observed by transmission electron microscopy (TEM), and qRT-PCR and Western blotting were used to detect autophagy-related factor levels. Immunohistochemistry and TUNEL staining were used to evaluate the apoptosis of liver tissues. Flow cytometry was used to detect the composition of immune cells. ELISA was used to evaluate the expression of serum inflammatory factors. Transcript-proteome sequencing, molecular docking, qRT-PCR, and Western blotting were performed to explore the mechanism and target of SDS in NASH.

Results

The oral administration of SDS demonstrated comprehensive efficacy in NASH. SDS showed both promising preventive and therapeutic effects on NASH in vivo. SDS could upregulate autophagy, downregulate apoptosis, rebalance immunity, and alleviate inflammation to exert anti-NASH properties. Finally, the results of transcript-proteome sequencing, molecular docking evaluation, and experimental validation showed that SDS might exert its multiple effects through targeting PPARα.

Conclusion

Our findings revealed that SDS could regulate liver autophagy and apoptosis, regulating both innate immunity and adaptive immunity and alleviating inflammation in NASH prevention and therapy via the PPAR pathway, suggesting that SDS could be a potential anti-NASH drug in the future.

Effects of dietary curcumin nano-micelles on performance, biological responses, and thermal stress resilience in heat-stressed fattening lambs across varying temperature-humidity index conditions: Implications for climate change

Heat stress poses a significant challenge to sheep farming in arid and semi-arid regions, impacting growth performance, health, and physiological responses. While sheep have innate mechanisms to manage heat stress, prolonged exposure impairs their performance and health. This study evaluated the influence of varying doses of Curcumin Nano-Micelle (CNM) on heat-stressed fattening lambs in northeastern Iran over three months, examining the relationship between CNM doses and growth performance, feeding behavior, physiological responses, immune function, and antioxidant status. Thirty-two crossbred male lambs were included in a completely randomized design with four treatments and eight replications. The experimental treatments were as follows: 1) CTRL: No dietary inclusion of CNM, (control group); 2) T20: Dietary inclusion of 20 mg of CNM per head per day; 3) T40: Dietary inclusion of 40 mg of CNM per head per day; and 4) T80: Dietary inclusion of 80 mg of CNM per head per day. The results revealed that dietary supplementation with 20 and 40 mg of CNM significantly improved live body weight, weight gain, average daily gain (ADG), and feed conversion ratio (FCR) compared to the control treatment. Regression analysis demonstrated quadratic models between growth performance parameters and the Temperature-Humidity Index (THI), indicating a correlation between CNM doses and the animals' responses to heat stress. Regarding eating behavior, CNM doses of 40 and 80 mg/day significantly reduced eating time while increasing ruminating time. Blood analysis indicated significant reductions in glucose levels across all treatments, with T40 significantly reducing both cholesterol and triglyceride (TG) levels. Additionally, CNM supplementation decreased serum malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, indicating enhanced antioxidant status. Physiological responses were influenced by CNM, notably reducing rectal temperature (RT), skin temperature (ST), respiration rate (RR), while pulse rate (PR) increased across various time intervals, particularly in the T80 group. This study demonstrates that CNM supplementation can enhance performance, physiological responses, and antioxidant status in heat-stressed fattening lambs, highlighting its potential to mitigate heat stress effects in sheep farming.

Curcumin protects mice with myasthenia gravis by regulating the gut microbiota, short-chain fatty acids, and the Th17/Treg balance

Curcumin is widely used as a traditional drug in Asia. Interestingly, curcumin and its metabolites have been demonstrated to influence the microbiota. However, the effect of curcumin on the gut microbiota in patients with myasthenia gravis (MG) remains unclear. This study aimed to investigate the effects of curcumin on the gut microbiota community, short-chain fatty acids (SCFAs) levels, intestinal permeability, and Th17/Treg balance in a Torpedo acetylcholine receptor (T-AChR)-induced MG mouse model. The results showed that curcumin significantly alleviated the clinical symptoms of MG mice induced by T-AChR. Curcumin modified the gut microbiota composition, increased microbial diversity, and, in particular, reduced endotoxin-producing Proteobacteria and Desulfovibrio levels in T-AChR-induced gut dysbiosis. Moreover, we found that curcumin significantly increased fecal butyrate levels in mice with T-AChR-induced gut dysbiosis. Butyrate levels increased in conjunction with the increase in butyrate-producing species such as Oscillospira, Akkermansia, and Allobaculum in the curcumin-treated group. In addition, curcumin repressed the increased levels of lipopolysaccharide (LPS), zonulin, and FD4 in plasma. It enhanced Occludin expression in the colons of MG mice induced with T-AChR, indicating dramatically alleviated gut permeability. Furthermore, curcumin treatment corrected T-AChR-induced imbalances in Th17/Treg cells. In summary, curcumin may protect mice against myasthenia gravis by modulating both the gut microbiota and SCFAs, improving gut permeability, and regulating the Th17/Treg balance. This study provides novel insights into curcumin's clinical value in MG therapy.

Podocin, mTOR, and CHOP dysregulation contributes to nephrotoxicity induced of lipopolysaccharide/diclofenac combination in rats: Curcumin and silymarin could afford protective effect

AIM

Sepsis is a common cause of acute kidney injury (AKI). Lipopolysaccharides (LPS) are the main gram-negative bacterial cell wall component with a well-documented inflammatory impact. Diclofenac (DIC) is a non-steroidal anti-inflammatory drug with a potential nephrotoxic effect. Curcumin (CUR) and silymarin (SY) are natural products with a wide range of pharmacological activities, including antioxidant and anti-inflammatory ones. The objective of this study was to examine the protective impact of CUR and SY against kidney damage induced by LPS/DIC co-exposure.

MATERIALS AND METHODS

Four groups of rats were used; control; LPS/DIC, LPS/DIC + CUR, and LPS/DIC + SY group. LPS/DIC combination induced renal injury at an LPS dose much lower than a nephrotoxic one.

KEY FINDING

Nephrotoxicity was confirmed by histopathological examination and significant elevation of renal function markers. LPS/DIC induced oxidative stress in renal tissues, evidenced by decreasing reduced glutathione and superoxide dismutase, and increasing lipid peroxidation. Inflammatory response of LPS/DIC was associated with a significant increase of renal IL-1β and TNF-α. Treatment with either CUR or SY shifted measured parameters to the opposite side. Moreover, LPS/DIC exposure was associated with upregulation of mTOR and endoplasmic reticulum stress protein (CHOP) and downregulation of podocin These effects were accompanied by reduced gene expression of cystatin C and KIM-1. CUR and SY ameliorated LPS/DIC effect on the aforementioned genes and protein significantly.

SIGNIFICANCE

This study confirms the potential nephrotoxicity; mechanisms include upregulation of mTOR, CHOP, cystatin C, and KIM-1 and downregulation of podocin. Moreover, both CUR and SY are promising nephroprotective products against LPS/DIC co-exposure.

Valuable effects of lactobacillus and citicoline on steatohepatitis: role of Nrf2/HO-1 and gut microbiota

Non-alcoholic steatohepatitis (NASH) is a more dangerous form of chronic non-alcoholic fatty liver disease (NAFLD). In the current investigation, the influence of citicoline on high-fat diet (HFD)-induced NASH was examined, both alone and in combination with Lactobacillus (probiotic). NASH was induced by feeding HFD (10% sugar, 10% lard stearin, 2% cholesterol, and 0.5% cholic acid) to rats for 13 weeks and received single i.p. injection of streptozotocin (STZ, 30 mg/kg) after 4 weeks. Citicoline was given at two dose levels (250 mg and 500 mg, i.p.) at the beginning of the sixth week, and in combination with an oral suspension of Lactobacillus every day for eight weeks until the study's conclusion. HFD/STZ induced steatohepatitis as shown by histopathological changes, elevated serum liver enzymes, serum hyperlipidemia and hepatic fat accumulation. Moreover, HFD convinced oxidative stress by increased lipid peroxidation marker (MDA) and decreased antioxidant enzymes (GSH and TAC). Upregulation of TLR4/NF-kB and the downstream inflammatory cascade (TNF-α, and IL-6) as well as Pentaraxin, fetuin-B and apoptotic markers (caspase-3 and Bax) were observed. NASH rats also had massive increase in Bacteroides spp., Fusobacterium spp., E. coli, Clostridium spp., Providencia spp., Prevotella interrmedia, and P. gingivalis while remarkable drop in Bifidobacteria spp. and Lactobacillus spp. Co-treatment with citicoline alone and with Lactobacillus improve histopathological NASH outcomes and reversed all of these molecular pathological alterations linked to NASH via upregulating the expression of Nrf2/HO-1 and downregulating TLR4/NF-kB signaling pathways. These results suggest that citicoline and lactobacillus may represent new hepatoprotective strategies against NASH progression.

Valuable effects of lactobacillus and citicoline on steatohepatitis: role of Nrf2/HO-1 and gut microbiota

Non-alcoholic steatohepatitis (NASH) is a more dangerous form of chronic non-alcoholic fatty liver disease (NAFLD). In the current investigation, the influence of citicoline on high-fat diet (HFD)-induced NASH was examined, both alone and in combination with Lactobacillus (probiotic). NASH was induced by feeding HFD (10% sugar, 10% lard stearin, 2% cholesterol, and 0.5% cholic acid) to rats for 13 weeks and received single i.p. injection of streptozotocin (STZ, 30 mg/kg) after 4 weeks. Citicoline was given at two dose levels (250 mg and 500 mg, i.p.) at the beginning of the sixth week, and in combination with an oral suspension of Lactobacillus every day for eight weeks until the study’s conclusion. HFD/STZ induced steatohepatitis as shown by histopathological changes, elevated serum liver enzymes, serum hyperlipidemia and hepatic fat accumulation. Moreover, HFD convinced oxidative stress by increased lipid peroxidation marker (MDA) and decreased antioxidant enzymes (GSH and TAC). Upregulation of TLR4/NF-kB and the downstream inflammatory cascade (TNF-α, and IL-6) as well as Pentaraxin, fetuin-B and apoptotic markers (caspase-3 and Bax) were observed. NASH rats also had massive increase in Bacteroides spp., Fusobacterium spp., E. coli, Clostridium spp., Providencia spp., Prevotella interrmedia, and P. gingivalis while remarkable drop in Bifidobacteria spp. and Lactobacillus spp. Co-treatment with citicoline alone and with Lactobacillus improve histopathological NASH outcomes and reversed all of these molecular pathological alterations linked to NASH via upregulating the expression of Nrf2/HO-1 and downregulating TLR4/NF-kB signaling pathways. These results suggest that citicoline and lactobacillus may represent new hepatoprotective strategies against NASH progression.

Effects of dietary curcumin nano-micelles on growth performance, blood metabolites, antioxidant status, immune and physiological responses of fattening lambs under heat-stress conditions

The aim of the current study was to investigate the effects of dietary curcumin nano-micelles (C-NM) on the growth performance, blood metabolites, antioxidant status, and immune and physiological responses of fattening lambs under heat stress conditions. Thirty-two crossbred male lambs [Île-de-France × (Dalagh × Romanov)] with an average weight of 31.2 ± 1.55 kg and age of 4-5 months were assigned to experimental treatments in a completely randomized design including four treatments and eight replications. The treatments were T0, T20, T40, and T80, representing dietary supplementation of C-NM at 0, 20, 40, and 80 mg per head per day, respectively. The study lasted for 37 days including 7 days of adaptation period. Lambs were weighed on days 0 and 30 of the experiment before morning feeding to determine the average daily gain (ADG) and feed conversion ratio (FCR). Blood samples were collected from the jugular vein on day 30 of the experiment and physiological parameters, including rectal temperature (RT), skin temperature (ST), respiration rate (RR), and pulse rate (PR), were measured once a week on a certain day during the study. Lambs in the T40 group showed higher final live weight (FLW) and ADG, while exhibiting lower FCR (P < 0.01). Regression analysis predicted the optimum levels of dietary inclusion of C-NM to be 44.7, 38.3, and 42.0 mg/day for FLW, ADG, and FCR, respectively. Dietary supplementation of C-NM decreased RT, ST, and RR, while increasing PR (P < 0.01). The levels of immunoglobulins G (IgG) and A (IgA) increased linearly with the dietary inclusion of C-NM (P < 0.01), while levels of immunoglobulin M (IgM) remained unaffected (P > 0.05). Dietary inclusion of C-NM had a quadratic reducing effect on the serum concentration of malondialdehyde (MDA) and a cubic increasing effect on the serum activities of glutathione peroxidase (GPx) (P < 0.05). Superoxide dismutase (SOD) was linearly increased in T80, while total antioxidant capacity (TAC) showed a linear increase in T40 and T80 groups (P < 0.01). Based on the results of this study, we recommend the administration of C-NM in the diet of fattening lambs during hot months in tropical and subtropical areas. However, further studies are needed to assess the long-term effects of C-NM during various physiological and production statuses.

The Development of Dyslipidemia in Chronic Kidney Disease and Associated Cardiovascular Damage, and the Protective Effects of Curcuminoids

Chronic kidney disease (CKD) is a health problem that is constantly growing. This disease presents a diverse symptomatology that implies complex therapeutic management. One of its characteristic symptoms is dyslipidemia, which becomes a risk factor for developing cardiovascular diseases and increases the mortality of CKD patients. Various drugs, particularly those used for dyslipidemia, consumed in the course of CKD lead to side effects that delay the patient's recovery. Therefore, it is necessary to implement new therapies with natural compounds, such as curcuminoids (derived from the Curcuma longa plant), which can cushion the damage caused by the excessive use of medications. This manuscript aims to review the current evidence on the use of curcuminoids on dyslipidemia in CKD and CKD-induced cardiovascular disease (CVD). We first described oxidative stress, inflammation, fibrosis, and metabolic reprogramming as factors that induce dyslipidemia in CKD and their association with CVD development. We proposed the potential use of curcuminoids in CKD and their utilization in clinics to treat CKD-dyslipidemia.

Mechanistic insights into the renoprotective role of curcumin in cisplatin-induced acute kidney injury: network pharmacology analysis and experimental validation

Cisplatin-induced acute kidney injury (CP-AKI) is a severe complication in patients receiving CP chemotherapy. However, effective therapies for CP-AKI are currently lacking. Curcumin (CUR), a natural polyphenol, is extracted from the rhizome of turmeric and has been reported to have nephroprotective activity. However, the role of CUR in CP-AKI remains unclear. This study aimed to explore the mechanism of CUR in CP-AKI by combining a network pharmacology approach with experimental validations. The analysis revealed 176 potential targets of CUR based on the HERB database and 1,286 related targets of CP-AKI from the GeneCards, DrugBank, and OMIM databases. Further, 106 common targets of CUR against CP-AKI were obtained, and these common targets constructed a protein-protein interaction (PPI) network. In addition, the core targets were screened from the PPI network using Cytoscape. Molecular docking revealed that CUR displayed the best binding to AKT1. Gene Ontology (GO) analysis indicated that the primary biological processes of CUR against CP-AKI included cellular response to chemical stress and apoptotic regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis suggested that the PI3K-Akt signaling pathway was most significantly enriched in CUR against CP-AKI. Western blotting and flow cytometry showed that CUR inhibited apoptosis induced by CP by activating the Akt signaling pathway in human kidney tubular epithelial cells (HK-2). Altogether, our findings demonstrated that CUR alleviated apoptosis by activating the Akt signaling pathway in CP-AKI in vitro. These data provide a scientific basis for future investigations into the clinical application of CUR against CP-AKI.

A Review of Traditional Chinese Medicine in Treating Renal Interstitial Fibrosis via Endoplasmic Reticulum Stress-Mediated Apoptosis

Renal interstitial fibrosis (RIF) is the main pathological manifestation of end-stage renal disease. Recent studies have shown that endoplasmic reticulum (ER) stress is involved in the pathogenesis and development of RIF. Traditional Chinese medicine (TCM), as an effective treatment for kidney diseases, can improve kidney damage by affecting the apoptotic signaling pathway mediated by ER stress. This article reviews the apoptotic pathways mediated by ER stress, including the three major signaling pathways of unfolded protein response, the main functions of the transcription factor C/EBP homologous protein. We also present current research on TCM treatment of RIF, focusing on medicines that regulate ER stress. A new understanding of using TCM to treat kidney disease by regulating ER stress will promote clinical application of Chinese medicine and discovery of new drugs for the treatment of RIF.

New insight and potential therapy for NAFLD: CYP2E1 and flavonoids

Over the years, the prevalence of nonalcoholic fatty liver disease (NAFLD) has increased year by year; however, due to its complicated pathogenesis, there is no effective treatment so far. It is reported that Cytochrome P450 2E1 (CYP2E1) plays an indispensable role in the development of NAFLD, and numerous studies have shown that flavonoids have a hepatoprotective effect and can exert a beneficial effect on NAFLD by regulating the activity of CYP2E1. Therefore, flavonoids may become effective drugs for the treatment of NAFLD in the future. This prompted us to review the research progress of the pathological mechanism of NAFLD and the impact of CYP2E1 activity changes during the pathological process, and to summarize the protective effect of flavonoids against CYP2E1 activity.

Curcumin exerts hepatoprotection via overexpression of Paraoxonase-1 and its regulatory genes in rats undergone bile duct ligation

OBJECTIVES

Curcumin is described as an antioxidant, hepato-protective and antifibrotic in liver fibrosis, although its mechanism is still not known. One of the models of the chronic liver disease stemming from oxidative stress and the generation of free radical has been considered to be bile duct ligation (BDL). Paraoxonase 1 (PON1) is a prominent antioxidant enzyme. Therefore, the objective of the present research is to assess the effects of curcumin on upregulation of PON1 in BDL rats.

METHODS

As predicted, the rats have been divided into the four groups of Sham, Sham + Cur (curcumin), BDL and BDL + Cur. We evaluated the efficacy of curcumin (100 mg/kg/day) on protein and gene expression of PON1 and regulatory genes contributed to the gene expression PON1 such as Sp1, PKCα, SREBP-2, AhR, JNK and regulation PON1 activity gene expression of Apo A1.

RESULTS

Curcumin attenuated alterations in liver histology, hepatic enzymes and the mRNA expression of fibrotic markers (p<0.05). In addition, curcumin increased significantly mRNA, protein expression of PON1 and mRNA of the genes that are contributed to the expression of PON1 such as Sp1, PKCα, SREBP-2, AhR, JNK and increased PON1 activity through upregulation of Apo A1 (p<0.05).

CONCLUSIONS

Cirrhosis progression may be inhibited by treatment with curcumin through the increased influence the expression and activity of PON1.

Curcumin attenuates angiotensin II-induced podocyte injury and apoptosis by inhibiting endoplasmic reticulum stress

Podocytes are an important component of the glomerular filtration barrier in the kidneys. The dysfunction and apoptosis of podocytes are important factors that can lead to the progression of chronic kidney disease (CKD). In CKD, angiotensin II is continuously elevated in circulation and is considered to have key roles in inducing podocyte injury and apoptosis. Curcumin is a hydrophobic polyphenolic compound extracted from turmeric. Increasing evidence demonstrates that curcumin has a protective effect on the kidneys in CKD. However, the mechanisms mediating this protective effect remain unclear. The aim of this study was to explore whether curcumin could protect against angiotensin II‐induced injury and apoptosis of podocytes. We performed western blotting, immunofluorescence, phalloidin staining, and terminal deoxynucleotidyl transferase nick‐end labeling staining to observe the expression level of podocyte‐specific proteins, apoptosis‐related proteins, and the arrangement of F‐actin. We found that curcumin could reverse angiotensin II‐induced podocyte injury and apoptosis in a dose‐dependent manner. In addition, curcumin dose‐dependently attenuated a pro‐apoptotic pathway, activated by angiotensin II‐induced endoplasmic reticulum stress. Conversely, the protective effects of curcumin were impaired upon addition of tunicamycin, an activator of endoplasmic reticulum stress. Thus, we speculate that curcumin protects against angiotensin II‐induced podocyte injury and apoptosis, at least partly by inhibiting endoplasmic reticulum stress.

Roles of Hepatic Innate and Innate-Like Lymphocytes in Nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH), a progressive form of nonalcoholic fatty liver disease (NAFLD), is accompanied by steatosis, hepatocyte injury and liver inflammation, which has been a health problem in the world as one of the major high risk factors of cirrhosis and hepatocellular carcinoma (HCC). Complex immune responses involving T cells, B cells, Kupffer cells, monocytes, neutrophils, DCs and other innate lymphocytes account for the pathogenesis of NASH; however, the underlying mechanisms have not been clearly elucidated in detail. In the liver, innate and innate-like lymphocytes account for more than two-thirds of total lymphocytes and play an important role in maintaining the immune homeostasis. Therefore, their roles in the progression of NASH deserves investigation. In this review, we summarized murine NASH models for immunological studies, including the diet-induced NASH, chemical-induced NASH and genetic-induced NASH. The role of innate and innate-like lymphocytes including NK cells, ILCs, NKT, γδT and MAIT cells in the progression of NASH were elucidated. Further, the metabolic regulation of the innate immune response was addressed in consideration to explain the molecular mechanisms. Based on the findings of the reviewed studies, strategies of immune intervention are proposed to control the progression of NASH.

Targeting DUSP7 signaling alleviates hepatic steatosis, inflammation and oxidative stress in high fat diet (HFD)-fed mice via suppression of TAK1

The non-alcoholic fatty liver disease (NAFLD), as a critical liver disease, is still lack of effective treatments because the molecular mechanism revealing the NAFLD pathogenesis remains unclear. Dual specific phosphatase 6 (DUSP7) shows effects on inflammatory response and is a negative feedback mechanism of the mitogen-activated protein kinase (MAPK) superfamily, which are critical factors in regulating NAFLD progression. However, the effects of DUSP7 on hepatic steatosis are still not fully understood. Here, we found that DUSP7 functioned as a negative regulator of NAFLD and in various metabolic disorders. DUSP7 expression was markedly reduced in liver samples from patients with simple hepatic steatosis or non-alcoholic steatohepatitis (NASH), as well as in liver tissues from high fat diet (HFD)-challenged mice or genetically obese (ob/ob) mice. DUSP7 knockout markedly accelerated insulin resistance, glucose intolerance, liver dysfunction, fibrosis and hepatic steatosis in HFD-fed mice. In addition, inflammatory response was significantly exacerbated in HFD-challenged mice with DUSP7 deletion, which was associated with the elevated activation of nuclear factor-κB (NF-κB) and MAPKs signaling pathways. Moreover, oxidative stress was detected in liver of HFD-induced mice, and this phenomenon was aggravated in mice with DUSP7 knockout. Importantly, we demonstrated that DUSP7 physically interacted with transforming growth factor β (TGF-β)-activated kinase (TAK1). DUSP7 deletion considerably promoted the activation of TAK1 in mice after HFD feeding, contributing to the lipid deposition, inflammatory response and reactive oxygen species (ROS) production. Taken together, DUSP7 might function as a protective factor against NAFLD development and metabolic disorder through alleviating dyslipidemia, inflammation and oxidative stress by directly interacting with TAK1 in hepatocytes, which was involved in the suppression of fibrosis. Thus, we may provide an effective strategy for the treatment of hepatic steatosis via targeting DUSP7.

Protective Effect of Curcumin on Acrylamide-Induced Hepatic and Renal Impairment in Rats: Involvement of CYP2E1

As a chemical extensively used in industrial areas and formed during heating of carbohydrate-rich foods and tobacco, acrylamide (ACR) has been demonstrated to exert a variety of systemic toxic effects including hepatotoxicity and nephrotoxicity. In the present study, we investigated the effect of curcumin, a natural polyphenolic compound in a popular spice known as turmeric, on the hepatic and renal impairment caused by ACR exposure to 40 mg/kg for 4 weeks in rats. The administration of curcumin at doses of 50 and 100 mg/kg to ACR-intoxicated rats significantly decreased the serum levels of alanine transaminase, aspartate transaminase, creatinine, and urea; improved the histological changes of liver and kidney caused by ACR; reduced the number of apoptotic cells; as well as relieved ACR-induced hepatic and renal oxidative stress. Moreover, curcumin inhibited the CYP2E1 overexpression induced by ACR in the liver and kidney tissues. Therefore, curcumin could be applied as a potential strategy for the intervention of ACR-induced systemic toxicity. The inhibition of CYP2E1 might be involved in the protection of curcumin against ACR-induced hepatotoxicity and nephrotoxicity.

Curcumin protects against palmitic acid-induced apoptosis via the inhibition of endoplasmic reticulum stress in testicular Leydig cells

BACKGROUND

Palmitic acid (PA) is a common saturated fatty acid that induces apoptosis in various types of cells, including testicular Leydig cells. There is evidence suggesting that PA is increased in patients with obesity and that PA-induced cell apoptosis may play an important role in obesity-related male infertility. Curcumin, a natural polyphenol, has been reported to exert cytoprotective effects in various cell types. However, the cytoprotective effect of curcumin against PA-induced apoptosis in Leydig cells remains unknown. Therefore, the current study was performed to investigate the protective effects of curcumin in response to PA-induced toxicity and apoptosis in murine Leydig tumor cell line 1 (MLTC-1) cells and explore the mechanism underlying its anti-apoptotic action.

METHODS

MLTC-1 cells were cultured in Roswell Park Institute-1640 medium and divided into five groups. First four groups were treated with 50-400 μM PA, 400 μM PA + 5-40 μM curcumin, 400 μM PA + 500 nM 4-phenylbutyric acid (4-PBA, an endoplasmic reticulum (ER) stress inhibitor), and 500 nM thapsigargin (TG, an ER stress inducer) + 20 μM curcumin, respectively, followed by incubation for 24 h. Effects of PA and/or curcumin on viability, apoptosis, and ER stress in MLTC-1 cells were then determined by cell proliferation assay, flow cytometry, and western blot analysis. The fifth group of MLTC-1 cells was exposed to 400 μM of PA and 5 IU/mL of human chorionic gonadotropin (hCG) for 24 h in the absence and presence of curcumin, followed by measurement of testosterone levels in cell-culture supernatants by enzyme-linked immunosorbent assay (ELISA). Rats fed a high-fat diet (HFD) were treated with or without curcumin for 4 weeks, and the testosterone levels were detected by ELISA.

RESULTS

Exposure to 100-400 μM PA reduced cell viability, activated caspase 3, and enhanced the expression levels of the apoptosis-related protein BCL-2-associated X protein (BAX) and ER stress markers glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) in MLTC-1 cells. Treating cells with 500 nM 4-PBA significantly attenuated PA-induced cytotoxicity through inhibition of ER stress. Curcumin (20 μM) significantly suppressed PA- or TG-induced decrease in cell viability, caspase 3 activity, and the expression levels of BAX, CHOP, and GRP78. In addition, treating MLTC-1 cells with 20 μM curcumin effectively restored testosterone levels, which were reduced in response to PA exposure. Similarly, curcumin treatment ameliorated the HFD-induced decrease in serum testosterone level in vivo.

CONCLUSIONS

The present study suggests that PA induces apoptosis via ER stress and curcumin ameliorates PA-induced apoptosis by inhibiting ER stress in MLTC-1 cells. This study suggests the application of curcumin as a potential therapeutic agent for the treatment of obesity-related male infertility.

Curcumin attenuates palmitic acid-induced cell apoptosis by inhibiting endoplasmic reticulum stress in H9C2 cardiomyocytes

Diabetic cardiomyopathy is mediated by multiple molecular mechanisms including endoplasmic reticulum (ER) stress. Curcumin, a phenolic compound, has cytoprotective properties, but its potential protective action against diabetic cardiomyopathy and the related molecular mechanisms are not fully elucidated. In this study, we evaluated the effects of curcumin on cell viability and apoptosis in palmitic acid (PA)-treated H9C2 cardiomyocytes and investigated the signaling pathways involved. Treatment with PA reduced cell viability, induced apoptosis, enhanced apoptosis-related protein expression (Caspase 3 and BCL-2 associated X protein (BAX)), and activated ER stress marker protein expression (glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP)). Curcumin attenuated PA-induced reduction in cell viability and activation of apoptosis, Caspase 3 activity, BAX, CHOP, and GRP78 expression. 4-Phenylbutyric acid (4-PBA) attenuated the PA-induced effects on cell viability and apoptosis, similar to curcumin. Both curcumin and 4-PBA also attenuated PA-induced increase in ER stress protein (CHOP and GRP78) expression. Curcumin also protected against cytotoxicity, apoptosis, and ER stress induced by thapsigargin. These findings indicate that PA triggers apoptosis in H9C2 cells via ER stress pathways and curcumin protects against this phenomenon.

Cellular and molecular mechanisms of curcumin in prevention and treatment of disease

Curcumin is a naturally occurring polyphenolic compound present in rhizome of Curcuma longa belonging to the family zingiberaceae. Growing experimental evidence revealed that curcumin exhibit multitarget biological implications signifying its crucial role in health and disease. The current review highlights the recent progress and mechanisms underlying the wide range of pharmacological effects of curcumin against numerous diseases like neuronal, cardiovascular, metabolic, kidney, endocrine, skin, respiratory, infectious, gastrointestinal diseases and cancer. The ability of curcumin to modulate the functions of multiple signal transductions are linked with attenuation of acute and chronic diseases. Numerous preclinical and clinical studies have revealed that curcumin modulates several molecules in cell signal transduction pathway including PI3K, Akt, mTOR, ERK5, AP-1, TGF-β, Wnt, β-catenin, Shh, PAK1, Rac1, STAT3, PPARγ, EBPα, NLRP3 inflammasome, p38MAPK, Nrf2, Notch-1, AMPK, TLR-4 and MyD-88. Curcumin has a potential to prevent and/or manage various diseases due to its anti-inflammatory, anti-oxidant and anti-apoptotic properties with an excellent safety profile. In contrast, the anti-cancer effects of curcumin are reflected due to induction of growth arrest and apoptosis in various premalignant and malignant cells. This review also carefully emphasized the pharmacokinetics of curcumin and its interaction with other drugs. Clinical studies have shown that curcumin is safe at the doses of 12 g/day but exhibits poor systemic bioavailability. The use of adjuvant like piperine, liposomal curcumin, curcumin nanoparticles and curcumin phospholipid complex has shown enhanced bioavailability and therapeutic potential. Further studies are warranted to prove the potential of curcumin against various ailments.

EndophilinA2 protects against angiotensin II-induced cardiac hypertrophy by inhibiting angiotensin II type 1 receptor trafficking in neonatal rat cardiomyocytes

Cardiac hypertrophy is one of the major risk factors for chronic heart failure. The role of endophilinA2 (EndoA2) in clathrin-mediated endocytosis and clathrin-independent endocytosis is well documented. In the present study, we tested the hypothesis that EndoA2 protects against angiotensin II (Ang II)-induced cardiac hypertrophy by mediating intracellular angiotensin II type 1 receptor (AT1-R) trafficking in neonatal rat cardiomyocytes (NRCMs). Cardiac hypertrophy was evaluated by using cell surface area and quantitative RT-PCR (qPCR) analyses. For the first time, we found that EndoA2 attenuated cardiac hypertrophy and fibrosis induced by Ang II. Moreover, EndoA2 inhibited apoptosis induced by excessive endoplasmic reticulum stress (ERS), which accounted for the beneficial effects of EndoA2 on cardiac hypertrophy. We further revealed that there was an interaction between EndoA2 and AT1-R.The expression levels of EndoA2, which inhibits AT1-R transport from the cytoplasm to the membrane, and the interaction between EndoA2 and AT1-R were obviously decreased after Ang II treatment. Furthermore, Ang II inhibited the co-localization of AT1-R with GRP-78, which was reversed by EndoA2 overexpression. In conclusion, our results suggested that EndoA2 plays a role in protecting against cardiac hypertrophy induced by Ang II, possibly by inhibiting AT1-R transport from the cytoplasm to the membrane to suppress signal transduction.

Curcumin attenuates hepatic fibrosis and insulin resistance induced by bile duct ligation in rats

Recent studies have strongly indicated the hepatoprotective effect of curcumin; however, the precise mechanisms are not well understood. This study aimed to determine the protective effect of curcumin on hepatic damage and hepatic insulin resistance in biliary duct ligated (BDL) fibrotic rat model. To accomplish this, male Wistar rats were divided into four groups (eight for each): sham group, BDL group, sham+Cur group and BDL+Cur group. The last two groups received curcumin at a dose of 100 mg/kg daily for 4 weeks. The mRNA/protein expression levels of Ras-related C3 botulinum toxin substrate 1 (Rac1), Rac1-GTP, dinucleotide phosphate oxidase 1 (NOX1), signal transducer and activator of transcription 3 (STAT3), suppressor of cytokine signalling 3 (SOCS3), insulin receptor substrate 1 (IRS1), extracellular signal-regulated kinase 1 (ERK1), specific protein 1 (Sp1) and hypoxia-inducible factor-1α (HIF-1α) were measured by real-time PCR and Western blotting, respectively. Fasting blood glucose, insulin and Leptin levels were determined and homoeostasis model assessment-estimated insulin resistance, as an index of insulin resistance, was calculated. Curcumin significantly attenuated liver injury and fibrosis, including amelioration of liver histological changes, reduction of hepatic enzymes, as well as decreased expression of liver fibrogenesis-associated variables, including Rac1, Rac1-GTP, NOX1, ERK1, HIF-1α and Sp1. Curcumin also attenuated leptin level and insulin resistance, which had increased in BDL rats (P<0·05). Furthermore, compared with the BDL group, we observed an increase in IRS1 and a decrease in SOCS3 and STAT3 expression in the curcumin-treated BDL group (P<0·05), indicating return of these parameters towards normalcy. In conclusion, Curcumin showed hepatoprotective activity against BDL-induced liver injury and hepatic insulin resistance by influencing the expression of some genes/proteins involved in these processes, and the results suggest that it can be used as a therapeutic option.

Dicalcium Silicate Induced Proinflammatory Responses through TLR2-Mediated NF-κB and JNK Pathways in the Murine RAW 264.7 Macrophage Cell Line

Proinflammatory responses are important aspects of the immune response to biomaterials, which may cause peri-implantitis and implant shedding. The purpose of this study was to test the cytotoxicity and proinflammatory effects of dicalcium silicate particles on RAW 264.7 macrophages and to investigate the proinflammatory response mechanism induced by C₂S and tricalcium phosphate (TCP). C₂S and TCP particles were characterized using scanning electron microscopy (SEM), energy spectrum analysis (EDS) and X-ray diffraction (XRD). Cytotoxicity and apoptosis assays with C₂S and TCP in the murine RAW 264.7 cell line were tested using the cell counting kit-8 (CCK-8) assay and flow cytometry (FCM). The detection results showed that C₂S and TCP particles had no obvious toxicity in RAW 264.7 cells and did not cause obvious apoptosis, although they both caused an oxidative stress response by producing ROS when the concentrations were at 100 μg/mL. C₂S particles are likely to induce a proinflammatory response by inducing high TLR2, TNF-α mRNA, TNF-α proinflammatory cytokine, p-IκB, and p-JNK1 + JNK2 + JNK3 expression levels. When we added siRNA-TLR2-1, a significant reduction was observed. These findings support the theory that C₂S particles induce proinflammatory responses through the TLR2-mediated NF-κB and JNK pathways in the murine RAW 264.7 macrophage cell line.