Papain Ameliorates Lipid Accumulation and Inflammation in High-Fat Diet-Induced Obesity Mice and 3T3-L1 Adipocytes via AMPK Activation

Ilex paraguariensis A.St.-Hil. improves lipid metabolism in high-fat diet-fed obese rats and suppresses intracellular lipid accumulation in 3T3-L1 adipocytes via the AMPK-dependent and insulin signaling pathways

Background

Obesity is closely associated with several chronic diseases, and adipose tissue plays a major role in modulating energy metabolism.

Objective

This study aimed to determine whether Mate, derived from I. paraguariensis A.St.-Hil., ameliorates lipid metabolism in 3T3-L1 adipocytes and high-fat diet (HFD)-fed obese Sprague-Dawley (SD) rats.

Design

3T3-L1 adipocytes were cultured for 7 days, following which intracellular lipid accumulation and expression levels of lipid metabolism-related factors were examined. Dorsomorphin was used to investigate the potential pathways involved, particularly the adenosine monophosphate-activated protein kinase (AMPK)- dependent pathway. Mate was administered to rat HFD-fed obese SD models for 8 consecutive weeks. The expression of lipid metabolism-related factors in the organs and tissues collected from dissected SD rats was evaluated.

Results

Mate suppressed intracellular lipid accumulation in 3T3-L1 adipocytes, increased the protein and gene expression levels of AMPK, hormone sensitive lipase (HSL), calmodulin kinase kinase (CaMKK), liver kinase B1 (LKB1), protein kinase A (PKA), CCAAT/enhancer binding protein β (C/EBPβ), insulin receptor b (IRβ), and insulin receptor substrate 1 (IRS1) (Tyr465), and decreased those of sterol regulatory element binding protein 1C (Srebp1c), fatty acid synthase (FAS), peroxisome-activated receptor γ (PPARγ), and IRS1 (Ser1101). Furthermore, an AMPK inhibitor abolished the effects exerted by Mate on intracellular lipid accumulation and HSL and FAS expression levels. Mate treatment suppressed body weight gain and improved serum cholesterol levels in HFD-fed obese SD rats. Treatment with Mate increased the protein and gene expression levels of AMPK, PKA, Erk1/Erk2 (p44/p42), and uncoupling protein 1 and reduced those of mammalian target of rapamycin, S6 kinase, Srebp1c, ap2, FAS, Il6, Adiponectin, Leptin, and Fabp4 in rat HFD-fed obese SD models.

Discussion and conclusions

Mate suppressed intracellular lipid accumulation in 3T3-L1 adipocytes and improved lipid metabolism in the epididymal adipose tissue of HFD-fed obese SD rats via the activation of AMPK-dependent and insulin signaling pathways.

Unveiling the Potent Fibrino(geno)lytic, Anticoagulant, and Antithrombotic Effects of Papain, a Cysteine Protease from Carica papaya Latex Using κ-Carrageenan Rat Tail Thrombosis Model

While fibrinolytic enzymes and thrombolytic agents offer assistance in treating cardiovascular diseases, the existing options are associated with a range of adverse effects. In our previous research, we successfully identified ficin, a naturally occurring cysteine protease that possesses unique fibrin and fibrinogenolytic enzymes, making it suitable for both preventing and treating cardiovascular disorders linked to thrombosis. Papain is a prominent cysteine protease derived from the latex of Carica papaya. The potential role of papain in preventing fibrino(geno)lytic, anticoagulant, and antithrombotic activities has not yet been investigated. Therefore, we examined how papain influences fibrinogen and the process of blood coagulation. Papain is highly stable at pH 4-11 and 37-60 °C via azocasein assay. In addition, SDS gel separation electrophoresis, zymography, and fibrin plate assays were used to determine fibrinogen and fibrinolysis activity. Papain has a molecular weight of around 37 kDa, and is highly effective in degrading fibrin, with a molecular weight of over 75 kDa. Furthermore, papain-based hemostatic performance was confirmed in blood coagulation tests, a blood clot lysis assay, and a κ-carrageenan rat tail thrombosis model, highlighting its strong efficacy in blood coagulation. Papain shows dose-dependent blood clot lysis activity, cleaves fibrinogen chains of Aα, Bβ, and γ-bands, and significantly extends prothrombin time (PT) and activated partial thromboplastin time (aPTT). Moreover, the mean length of the infarcted regions in the tails of Sprague-Dawley rats with κ-carrageenan was shorter in rats administered 10 U/kg of papain than in streptokinase-treated rats. Thus, papain, a cysteine protease, has distinct fibrin and fibrinogenolytic properties, suggesting its potential for preventing or treating cardiovascular issues and thrombosis-related diseases.

Hypolipidaemic effects of papaya (Carica papaya L.) juice on rats fed on a high fat and fructose diet

Papaya (Carica papaya L.) is a highly nutritious and less-caloric fruit, commonly consumed for its minerals and vitamins and hence may help in controlling obesity and abdominal discomforts. The present study investigated the hypolipidaemic effects of papaya juice extract on male Albino Wistar rats (7 weeks old; 185 ± 17 g) fed on a high fat and fructose diet (HFFD) for 6 weeks. The rats were divided into groups I-IV of five rats each and fed on either a HFFD (i.e. the Control), HFFD + 200 mg papaya, HFFD + 350 mg papaya or a HFFD + 500 mg papaya. On day 34, after an overnight fast, blood samples were obtained by cardiac puncture under 99⋅8 % Chloroform anaesthesia for the determination of serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c) and high-density cholesterol (HDL-c). The atherogenic (AI) and coronary risk (CRI) indices were also calculated. Statistical analysis was performed using ANOVA where means were separated using Tukey's HSD test. Resulted showed that all rats given papaya juice had an increasing, non-significant HDL-c and reduced LDL-c levels while rats fed on HFFD had the highest TC (53⋅2 mg/dl) and TG (37⋅6 mg/dl) levels. Papaya juice statistically reduced the AI and CRI of the rats. In conclusion, consumption of HFFD + 500 mg was the most effective in the reduction of rats' blood lipids and fats, due to its anti-obesity and hypolipidaemic properties, thus can be used in the management of dyspilidaemic disorders.

The Geroprotective Drug Candidate CMS121 Alleviates Diabetes, Liver Inflammation, and Renal Damage in db/db Leptin Receptor Deficient Mice

db/db mice, which lack leptin receptors and exhibit hyperphagia, show disturbances in energy metabolism and are a model of obesity and type 2 diabetes. The geroneuroprotector drug candidate CMS121 has been shown to be effective in animal models of Alzheimer's disease and aging through the modulation of metabolism. Thus, the hypothesis was that CMS121 could protect db/db mice from metabolic defects and thereby reduce liver inflammation and kidney damage. The mice were treated with CMS121 in their diet for 6 months. No changes were observed in food and oxygen consumption, body mass, or locomotor activity compared to control db/db mice, but a 5% reduction in body weight was noted. Improved glucose tolerance and reduced HbA1c and insulin levels were also seen. Blood and liver triglycerides and free fatty acids decreased. Improved metabolism was supported by lower levels of fatty acid metabolites in the urine. Markers of liver inflammation, including NF-κB, IL-18, caspase 3, and C reactive protein, were lowered by the CMS121 treatment. Urine markers of kidney damage were improved, as evidenced by lower urinary levels of NGAL, clusterin, and albumin. Urine metabolomics studies provided further evidence for kidney protection. Mitochondrial protein markers were elevated in db/db mice, but CMS121 restored the renal levels of NDUFB8, UQCRC2, and VDAC. Overall, long-term CMS121 treatment alleviated metabolic imbalances, liver inflammation, and reduced markers of kidney damage. Thus, this study provides promising evidence for the potential therapeutic use of CMS121 in treating metabolic disorders.

Papain Exerts an Anti-atherosclerosis Effect with Suppressed MPA-mediated Foam Cell Formation by Regulating the MAPK and PI3K/Akt-NF-κB Pathways

BACKGROUND

Papain possesses a potential anti-atherosclerosis (AS) effect. This study aimed to explore the inhibitory effects of papain on the monocyte-platelet aggregates (MPAs)-mediated production of foam cells in vitro and AS in vivo.

RESEARCH DESIGN AND METHODS

THP-1 cells were induced or treated by platelet, papain, nuclear factor-κB (NF-κB, p65) inhibitor, or NF-κB activator. An AS rat model was established and treated with papain. The THP-1 cells, macrophages, and foam cells were detected, and CD36, CD11b and CCR2 (macrophages) and CD14 and CD41 (MPAs) were measured. The levels of inflammatory factors, lipoprotein, and mitogen-activated protein kinase (MAPK, p38) and phosphoInositide-3 Kinase (PI3K)/Akt(protein kinase B, PKB)-NF-κB pathways proteins were determined. Finally, injury of the thoracic aorta of AS rats was observed.

RESULTS

Papain reduced macrophage production, lipid accumulation, and foam cell formation in vitro and downregulated the expression of monocyte chemoattractant protein 1 (MCP-1), prostaglandin E2 (PGE2), and cyclooxygenase 2 (COX2), and that of p38, c-Jun N-terminal protein kinase (JNK), Akt, and p65. Moreover, the inhibitory effects of papain were reversed by the NF-κB activator. Similarly, papain alleviated aortic smooth muscle hyperplasia, lipid droplet accumulation, and collagen diffusion and inhibited the secretion of inflammatory factors and the expression of p38, JNK, Akt, and p65 in vivo.

CONCLUSIONS

Papain inhibited MPA-induced foam cell formation by inactivating the MAPK and PI3K/Akt-NF-κB pathways, thereby exerting an anti-AS effect.

Pharmacological Treatments and Natural Biocompounds in Weight Management

The obesity pandemic is one of society’s most urgent public health concerns. One-third of the global adult population may fall under obese or overweight by 2025, suggesting a rising demand for medical care and an exorbitant cost of healthcare expenditure in the coming years. Generally, the treatment strategy for obese patients is largely patient-centric and needs dietary, behavioral, pharmacological, and sometimes even surgical interventions. Given that obesity cases are rising in adults and children and lifestyle modifications have failed to produce the desired results, the need for medical therapy adjunct to lifestyle modifications is vital for better managing obesity. Most existing or past drugs for obesity treatment target satiety or monoamine pathways and induce a feeling of fullness in patients, while drugs such as orlistat are targeted against intestinal lipases. However, many medications targeted against neurotransmitters showed adverse events in patients, thus being withdrawn from the market. Alternatively, the combination of some drugs has been successfully tested in obesity management. However, the demand for novel, safer, and more efficacious pharmaceutical medicines for weight management does exist. The present review elucidates the current understanding of the available anti-obesity medicines of synthetic and natural origin, their main mechanisms of action, and the shortcomings associated with current weight management drugs.

Ginsenoside Rd promotes omentin secretion in adipose through TBK1-AMPK to improve mitochondrial biogenesis via WNT5A/Ca2+ pathways in heart failure

Ginsenoside Rd is an active ingredient in Panax ginseng CA Mey and can be absorbed into the adipose tissue. Adipokines play an important role in the treatment of cardiovascular diseases. However, the potential benefit of Rd on heart failure (HF) and the underlying mechanism associated with the crosstalk between adipocytes and cardiomyocytes remains to be illustrated. Here, the results identified that Rd improved cardiac function and inhibited cardiac pathological changes in transverse aortic constriction (TAC), coronary ligation (CAL) and isoproterenol (ISO)-induced HF mice. And Rd promoted the release of omentin from the adipose tissue and up-regulated omentin expression in lipopolysaccharide (LPS)-induced 3T3-L1 adipocytes. Further, Rd could increase TBK1 and AMPK phosphorylation in adipocytes. And also, the TBK1-AMPK signaling pathway regulated the expression of omentin in LPS-induced adipocytes. Moreover, the omentin mRNA expression was significantly decreased by TBK1 knockdown in LPS-induced 3T3-L1 adipocytes. Additionally, molecular docking and SPR analysis confirmed that Rd had a certain binding ability with TBK1, and co-treatment with TBK1 inhibitors or TBK1 knockdown partially abolished the effect of Rd on increasing the omentin expression and the ratio of p-AMPK to AMPK in adipocytes. Moreover, we found that circulating omentin level diminished in the HF patients compared with healthy subjects. Meanwhile, the adipose tissue-specific overexpression of omentin improved cardiac function, reduced myocardial infarct size and ameliorated cardiac pathological features in CAL-induced HF mice. Consistently, exogenous omentin reduced mtROS levels and restored ΔψM to improve oxygen and glucose deprivation (OGD)-induced cardiomyocytes injury. Further, omentin inhibited the WNT5A/Ca²⁺ signaling pathway and promoted mitochondrial biogenesis function to ameliorate myocardial ischemia injury. However, WNT5A knockdown inhibited the impairment of mitochondrial biogenesis and partially counteracted the cardioprotective effect of omentin in vitro. Therefore, this study indicated that Rd promoted omentin secretion from adipocytes through the TBK1-AMPK pathway to improve mitochondrial biogenesis function via WNT5A/Ca²⁺ signaling pathway to ameliorate myocardial ischemia injury, which provided a new therapeutic mechanism and potential drugs for the treatment of HF.

Ketogenic Diet Increases Serum and White Adipose Tissue SIRT1 Expression in Mice

Overnutrition and its sequelae have become a global concern due to the increasing incidence of obesity and insulin resistance. A ketogenic diet (KD) is widely used as a dietary treatment for metabolic disorders. Sirtuin1 (SIRT1), a metabolic sensor which regulates fat homeostasis, is modulated by dietary interventions. However, the influence of nutritional ketosis on SIRT1 is still debated. We examined the effect of KD on adipose tissue, liver, and serum levels of SIRT1 in mice. Adult C57BL/6J male mice were randomly assigned to two isocaloric dietary groups and fed with either high-fat KD or normal chow (NC) for 4 weeks. Serum SIRT1, beta-hydroxybutyrate (βHB), glucose, and triglyceride levels, as well as SIRT1 expression in visceral (VAT), subcutaneous (SAT), and brown (BAT) adipose tissues, and in the liver, were measured. KD-fed mice showed an increase in serum βHB in parallel with serum SIRT1 (r = 0.732, p = 0.0156), and increased SIRT1 protein expression in SAT and VAT. SIRT1 levels remained unchanged in BAT and in the liver, which developed steatosis. Normal glycemia and triglycerides were observed. Under a KD, serum and white fat phenotypes show higher SIRT1, suggesting that one of the molecular mechanisms underlying a KD's potential benefits on metabolic health involves a synergistic interaction with SIRT1.

Anti-Inflammatory Function of Plant-Derived Bioactive Peptides: A Review

Inflammation is considered to be a crucial factor in the development of chronic diseases, eight of which were listed among the top ten causes of death worldwide in the World Health Organization’s World Health Statistics 2019. Moreover, traditional drugs for inflammation are often linked to undesirable side effects. As gentler alternatives to traditional anti-inflammatory drugs, plant-derived bioactive peptides have been shown to be effective interventions against various chronic diseases, including Alzheimer’s disease, cardiovascular disease and cancer. However, an adequate and systematic review of the structures and anti-inflammatory activities of plant-derived bioactive peptides has been lacking. This paper reviews the latest research on plant-derived anti-inflammatory peptides (PAPs), mainly including the specific regulatory mechanisms of PAPs; the structure–activity relationships of PAPs; and their enzymatic processing based on the structure–activity relationships. Moreover, current research problems for PAPs are discussed, such as the shallow exploration of mechanisms, enzymatic solution determination difficulty, low yield and unknown in vivo absorption and metabolism and proposed future research directions. This work aims to provide a reference for functional activity research, nutritional food development and the clinical applications of PAPs.

Anti-Obesity Effect of Porcine Collagen Peptide in 3T3-L1 Adipocytes and High-Fat Diet-Fed Mice by Regulating Adipogenesis

Obesity is one of the most common diseases caused by an imbalance in the intake and expenditure of energy, and it is associated with various metabolic complications. This study aimed at investigating the anti-obesity effects and mechanisms of porcine collagen peptide (PCP) using 3T3-L1 preadipocytes and high-fat diet (HFD)-fed mice. The PCP treatment significantly inhibited the adipocyte differentiation and attenuated the mRNA expression of transcription factors (CCAAT/enhancer-binding protein alpha [C/EBPα] and peroxisome proliferator-activated receptor gamma [PPARγ]) and the lipogenic gene (fatty acid synthase [FAS]) expression in 3T3-L1 preadipocytes. In the in vivo study, HFD-fed mice were fed low- (1.5 g/kg body weight/day) and high- (4.5 g/kg body weight/day) PCP for 12 weeks and compared with the normal diet-fed group and HFD-fed control group. The PCP-fed groups showed significantly lower body weight gain, white fat weight gain, serum triglycerides, and adipocyte size compared with the HFD-fed group. The changes in body fat were associated with the upregulation of adiponectin and the downregulation of leptin, C/EBPα, PPARγ, and FAS. These results suggest that PCP has the potential to reduce obesity by suppressing adipogenesis and could be applied as a functional food material.