Lycium barbarum polysaccharide attenuates cardiac hypertrophy, inhibits calpain-1 expression and inhibits NF-κB activation in streptozotocin-induced diabetic rats

NF-ĸB axis in diabetic neuropathy, cardiomyopathy and nephropathy: A roadmap from molecular intervention to therapeutic strategies

Diabetes mellitus (DM) is a metabolic illness defined by elevated blood glucose levels, mediating various tissue alterations, including the dysfunction of vital organs. Diabetes mellitus (DM) can lead to many consequences that specifically affect the brain, heart, and kidneys. These issues are known as neuropathy, cardiomyopathy, and nephropathy, respectively. Inflammation is acknowledged as a pivotal biological mechanism that contributes to the development of various diabetes consequences. NF-κB modulates inflammation and the immune system at the cellular level. Its abnormal regulation has been identified in several clinical situations, including cancer, inflammatory bowel illnesses, cardiovascular diseases, and Diabetes Mellitus (DM). The purpose of this review is to evaluate the potential impact of NF-κB on complications associated with DM. Enhanced NF-κB activity promotes inflammation, resulting in cellular harm and compromised organ performance. Phytochemicals, which are therapeutic molecules, can potentially decline the NF-κB level, therefore alleviating inflammation and the progression of problems correlated with DM. More importantly, the regulation of NF-κB can be influenced by various factors, such as TLR4 in DM. Highlighting these factors can facilitate the development of novel therapies in the future.

Chinese herbal medicine and active ingredients for diabetic cardiomyopathy: molecular mechanisms regulating endoplasmic reticulum stress

Background: Diabetic cardiomyopathy (DCM) is one of the serious microvascular complications of diabetes mellitus. It is often associated with clinical manifestations such as arrhythmias and heart failure, and significantly reduces the quality of life and years of survival of patients. Endoplasmic reticulum stress (ERS) is the removal of unfolded and misfolded proteins and is an important mechanism for the maintenance of cellular homeostasis. ERS plays an important role in the pathogenesis of DCM by causing cardiomyocyte apoptosis, insulin resistance, calcium imbalance, myocardial hypertrophy and fibrosis. Targeting ERS is a new direction in the treatment of DCM. A large number of studies have shown that Chinese herbal medicine and active ingredients can significantly improve the clinical outcome of DCM patients through intervention in ERS and effects on myocardial structure and function, which has become one of the hot research directions. Purpose: The aim of this review is to elucidate and summarize the roles and mechanisms of Chinese herbal medicine and active ingredients that have the potential to modulate endoplasmic reticulum stress, thereby contributing to better management of DCM. Methods: Databases such as PubMed, Web of Science, China National Knowledge Internet, and Wanfang Data Knowledge Service Platform were used to search, analyze, and collect literature, in order to review the mechanisms by which phytochemicals inhibit the progression of DCM by targeting the ERS and its key signaling pathways. Keywords used included "diabetic cardiomyopathy" and "endoplasmic reticulum stress." Results: This review found that Chinese herbs and their active ingredients can regulate ERS through IRE1, ATF6, and PERK pathways to reduce cardiomyocyte apoptosis, ameliorate myocardial fibrosis, and attenuate myocardial hypertrophy for the treatment of DCM. Conclusion: A comprehensive source of information on potential ERS inhibitors is provided in this review. The analysis of the literature suggests that Chinese herbal medicine and its active ingredients can be used as potential drug candidates for the treatment of DCM. In short, we cannot ignore the role of traditional Chinese medicine in regulating ERS and treating DCM, and look forward to more research and new drugs to come.

Lycium barbarum polysaccharide protects cardiomyocytes from hypoxia/reoxygenation injury via activation of SIRT3/CypD signaling

Background

Myocardial ischemia-reperfusion is a common pathological feature of many heart and vascular diseases, but the molecular mechanism of this process is still unclear, and there is no effective way to protect cardiomyocytes. The aim of this study was to examine the effects and underlying molecular mechanisms of Lycium barbarum polysaccharide (LBP) on myocardial ischemia-reperfusion injury in cardiomyocytes.

Methods

The cardiomyocyte cell line H9c2 were used to establish an in vitro hypoxia/reoxygenation (H/R) model. After treatment with LBP and/or the SIRT3 inhibitor 3-TYP, cell morphology was observed under the light microscopy. The Cell Counting Kit (CCK)-8 and 5-ethynyl-2'-deoxyuridine (EdU) assay were used to detect cell proliferation, and flow cytometry was performed to assess cell apoptosis. The lysine (166)-acetylation of CypD1 was determined by co-immunoprecipitation assay. Enzyme-linked immunosorbent assay (ELISA) was used to determine the lactate dehydrogenase (LDH) level in the culture medium. Na⁺-K⁺-ATPase activity, Ca²⁺-ATPase activity, and nitric oxide (NO) levels were measured.

Results

LBP alleviated cell damage and upregulated STIR3 expression in a dose-dependent manner. Upregulated SIRT3 expression and suppressed acetylation of CypD were also observed in H/R-induced H9c2 cells treated with LBP. Indeed, LBP remarkably reversed the inhibition of proliferation and cell apoptosis in H/R-induced H9c2 cells by activating SIRT3/CypD signaling. Blockade of SIRT3 with SIRT3 inhibitor (3-TYP) inhibited the protective effect of LBP on H9c2 cells. LBP markedly alleviated the H/R-induced increase of LDH release, and the decrease of Na⁺-K⁺-ATPase activity, Ca²⁺-ATPase activity, and NO levels. Inhibition of SIRT3 restored the protective effects of LBP.

Conclusions

LPB induced deacetylation of CypD by upregulating SIRT3, thereby protecting mitochondrial function and relieving H/R-induced injury in cardiomyocytes.

Toll-like receptors in cardiac hypertrophy

Toll-like receptors (TLRs) are a family of pattern recognition receptors (PRRs) that can identify pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). TLRs play an important role in the innate immune response, leading to acute and chronic inflammation. Cardiac hypertrophy, an important cardiac remodeling phenotype during cardiovascular disease, contributes to the development of heart failure. In previous decades, many studies have reported that TLR-mediated inflammation was involved in the induction of myocardium hypertrophic remodeling, suggesting that targeting TLR signaling might be an effective strategy against pathological cardiac hypertrophy. Thus, it is necessary to study the mechanisms underlying TLR functions in cardiac hypertrophy. In this review, we summarized key findings of TLR signaling in cardiac hypertrophy.

Structure of a new glycyrrhiza polysaccharide and its immunomodulatory activity

A component of licorice polysaccharide (GPS-1) was extracted from licorice, its primary structure was identified and characterized for the first time, and its immunomodulatory activity was studied. Crude licorice polysaccharide was isolated and purified by DEAE sepharose FF ion-exchange column chromatography and Chromdex 200 PG gel filtration column chromatography to obtain a purified Glycyrrhiza polysaccharide named GPS-1. NMR and methylation analysis revealed that GPS-1 is composed of homogalacturonan (HG)-type pectin with 4)-D-GalpA-(1 as the backbone. This study of GPS-1 also examined its significant role in regulating immune activity in vitro and in vivo. As a result, GPS-1 promoted the secretion of IFN-γ and IL-4 in mice and increased the proportion of CD3+CD4+ and CD3+CD8+ T lymphocytes in their spleens. Dendritic cells (DCs) treated with GPS-1 showed promotion of DC maturation, antigen presentation, and phagocytic capacity. The results suggest that GPS-1 is a potential immunomodulator that stimulates the immune system by regulating multiple signaling pathways. Combined with our characterization of the primary structure of GPS-1, the present investigation provides the basis for future study of the form-function relationship of polysaccharides.

Therapeutic Effects of Topical Application of Lycium barbarum Polysaccharide in a Murine Model of Dry Eye

Purpose

To evaluate the safety and efficacy of Lycium barbarum polysaccharide (LBP) eye drops in a murine model of dry eye disease (DED).

Methods

Six- to eight-week-old female C57BL/6 mice were subjected to a combination of desiccating stress (DS) and topical benzalkonium chloride (BAC) to induce DED. Five microliters of LBP eye drops (0.625, 2.5, or 12.5 mg/ml) or PBS was applied topically 3 times per day for 10 days to subsequently test their efficacy. Tear secretion, tear breakup time (TBUT), corneal irregularity, and corneal fluorescein staining scores were measured on days 3 and 10 after treatment. The expression of tumor necrosis factor-alpha (TNF-α) in the cornea was assessed by quantitative (q) RT–PCR on days 10. The ocular irritation of LBP eye drops of corresponding concentrations was evaluated on 10- to 12-week-old female Sprague–Dawley rats.

Results

Compared with PBS-treated groups, mice treated with 0.625, 2.5, and 12.5 mg/ml LBP showed a significant improvement in the clinical signs of DED in a dose-dependent manner, including corneal epithelial integrity, corneal regularity, and tear production, as well as significant inhibition of inflammatory cell infiltration and TNF-α expression levels in the cornea. All corresponding concentrations of LBP eye drops revealed no obvious ocular irritation.

Conclusion

Topical application of LBP could ameliorate dry eye in a murine model of DED without obvious ocular irritation.

Effect of Lycium barbarum Polysaccharide on Decreasing Serum Amyloid A3 Expression through Inhibiting NF-κB Activation in a Mouse Model of Diabetic Nephropathy

Lycium barbarum polysaccharide (LBP) as one of the main bioactive constituents of the fruit of Lycium barbarum L. (LBL.) has many pharmacological activities, but its antihyperglycemic activity is not fully understood yet. This study investigated the hypoglycemic and renal protective effects of LBP on high-fat diet/streptozotocin- (HFD/STZ-) induced diabetic nephropathy (DN) in mice. Blood glucose was assessed before and after 8-week administration of LBP, and the homeostasis model assessment-insulin resistance (HOMA-IR) index was calculated for evaluating the antidiabetic effect of LBP. Additionally, serum creatinine (sCr), blood urea nitrogen (BUN), and urine microalbumin were tested to evaluate the renal function. HE and PAS stainings were performed to evaluate the morphology and injury of the kidney. The results showed that LBP significantly reduces the glucose level and ameliorates the insulin resistance of diabetic mice. Importantly, LBP improves renal function by lowering the levels of sCr, BUN, and microalbumin in diabetic mice and relieves the injury in the renal glomeruli and tubules of the DN mice. Furthermore, LBP attenuates renal inflammation as evidenced by downregulating the mRNA levels of TNFα, IL1 β, IL6, and SAA3 in the renal cortex, as well as reducing the elevated circulating level and protein depositions of SAA3 in the kidney. In addition, our western blot results showed that NF-κB p65 nuclear translocation and the degradation of inhibitory κB-α (IκBα) occurred during the progress of inflammation, and such activated signaling was restrained by LBP. In conclusion, our findings suggest that LBP is a potential antidiabetic agent, which ameliorates the inflammation in DN through inhibiting NF-κB activation.

Lycium barbarum polysaccharide protects rats and cardiomyocytes against ischemia/reperfusion injury via Nrf2 activation through autophagy inhibition

The irreversible loss of cardiomyocytes is mainly the result of ischemic/reperfusion (I/R) myocardial injury, leading to persistent heart dysfunction and heart failure. It has been reported that Lycium barbarum polysaccharide (LBP) has protective effects on cardiomyocytes, but the specific mechanism is still not completely understood. The present study examined the protective role of LBP in myocardial I/R injury. Rats were subjected to myocardial I/R injury and LBP treatment. Moreover, rat myocardial H9C2 cells exposed to hypoxia/reoxygenation (H/R) were used to simulate cardiac injury during myocardial I/R process and were exposed to LBP, rapamycin (an autophagy activator) or nuclear factor-erythroid factor 2-related factor 2 (Nrf2) transfection. Morphological examination, histopathological examination and echocardiography were used to determine the cardiac injury after I/R injury. Cell viability and apoptosis were determined via MTT and flow cytometry assays, respectively. The levels of lactate dehydrogenase (LDH), creatine kinase (CK), cardiac troponin T (cTnT), IL-1β, IL-6, TNF-α, malondialdehyde (MDA) and superoxidase dismutase (SOD) in rat serum, hearts and/or cells were assessed using ELISAs. The expression levels of Beclin 1, LC3II/LC3I, P62 and Nrf2 were analyzed via reverse transcription-quantitative PCR and western blotting. The results demonstrated that LBP improved heart function and repaired cardiomyocyte damage in I/R model rats, as well as reduced the production of cTnT, CK, LDH, IL-1β, IL-6 and TNF-α. The in vitro study results indicated that LBP increased cell viability, the apoptosis rate, and the levels of SOD and P62, as well as reduced the levels of LDH, CK, IL-1β, IL-6, TNF-α, MDA, Beclin 1 and LC3-II/LC3-I in H/R-injured H9C2 cells. Moreover, LBP promoted Nrf2 nuclear translocation, but decreased Nrf2 expression in the cytoplasm. Rapamycin exacerbated the aforementioned effects in H/R injured H9C2 cells, and partially reversed LBP-induced effects. Overexpressing Nrf2 counteracted I/R-induced effects and partially resisted rapamycin-induced effects. These findings demonstrated that LBP exhibited a cardiac protective effect on the ischemic myocardium of rats after reperfusion and attenuated myocardial I/R injury via autophagy inhibition-induced Nrf2 activation.

Lycium barbarum polysaccharides inhibit ischemia/reperfusion-induced myocardial injury via the Nrf2 antioxidant pathway

Oxidative stress is considered to be one of main pathophysiological mechanisms in myocardial ischemia/reperfusion (I/R) injury. Lycium barbarum polysaccharides (LBP), the main ingredient of Lycium barbarum, have potential antioxidant activity. We aimed to investigate the effects of LBP on myocardial I/R injury and explore the underlying mechanisms. Myocardial I/R group was treated with or without LBP to evaluate oxidative stress markers and the role of Nrf2 signal pathway. Our results showed that I/R increased infarct size and the activities of creatine kinase (CK) and lactate dehydrogenase (LDH) when compared with control group. Meanwhile, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were enhanced and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) were decreased. These changes were associated with a significant increase in myocardial apoptosis, ultimately leading to cardiac dysfunction. LBP reduced infarct size (38.4 ± 2 % versus 19.4 ± 1.8 %, p < 0.05), CK and LDH activities and myocardial apoptotic index. Meanwhile, LBP suppressed the production of ROS and restored redox status. Additionally, LBP increased protein level of nuclear Nrf2 in vivo (2.1 ± 0.3 versus 3.8 ± 0.4, p < 0.05) and in vitro (1.9 ± 0.2 versus 3.8 ± 0.1, p < 0.05) and subsequently upregulated heme oxygenase 1 and NADPH dehydrogenase quinone 1 compared to I/R group. Interestingly, Nrf2 siRNA abolished the protective effects of LBP. LBP suppressed oxidative stress damage and attenuated cardiac dysfunction induced by I/R via activation of the Nrf2 antioxidant signal pathway.

Curcumin and its analog alleviate diabetes-induced damages by regulating inflammation and oxidative stress in brain of diabetic rats

BACKGROUND

Diabetic encephalopathy is a severe diabetes complication with cognitive dysfunction and neuropsychiatric disability. The mechanisms underlying diabetic encephalopathy is believed to be relevant with oxidative stress, vascular amylin deposition, immune receptors, inflammation, etc. This study wanted to evaluate the ability of curcumin and its analog A13 to alleviate oxidative stress and inflammation in diabetes-induced damages in brain.

METHODS

Sixty adult male Sprague-Dawley rats were divided into 5 groups: normal control (NC) group, diabetes mellitus (DM) group, curcumin-treated diabetes mellitus (CUR) group, high dose of A13-treated diabetes mellitus (HA) group, low dose of A13-treated diabetes mellitus (LA) group. Activation of the nuclear factor kappa-B (NF-κB p65) pathway was detected by RT-qPCR, immunohistochemical (IHC) staining and Western blot; oxidative stress was detected by biochemical detection kit; brain tissue sections were stained with hematoxylin-eosin (HE) staining and Myelin staining.

RESULTS

RT-qPCR, IHC staining and Western blot showed that curcumin and A13 treatment could inhibit the NF-κB p65 pathway. Curcumin and A13 increased the activity of superoxide dismutase and decreased the malondialdehyde level in the brain of diabetic rats. Furthermore, HE staining and Myelin staining demonstrated that the histological lesions of the brain in diabetic rats could be significantly ameliorated by curcumin and A13.

CONCLUSION

Curcumin analog A13 could alleviate the damages in the brain of diabetes rats by regulating the pathways of inflammation and oxidative stress. A13 may be a new potential therapeutic agent for diabetic encephalopathy.

NRF2-Related Epigenetic Modifications in Cardiac and Vascular Complications of Diabetes Mellitus

Diabetes mellitus (DM) is a highly prevalent chronic disease that is accompanied with serious complications, especially cardiac and vascular complications. Thus, there is an urgent need to identify new strategies to treat diabetic cardiac and vascular complications. Nuclear factor erythroid 2-related factor 2 (NRF2) has been verified as a crucial target for the prevention and treatment of diabetic complications. The function of NRF2 in the treatment of diabetic complications has been widely reported, but the role of NRF2-related epigenetic modifications remains unclear. The purpose of this review is to summarize the recent advances in targeting NRF2-related epigenetic modifications in the treatment of cardiac and vascular complications associated with DM. We also discuss agonists that could potentially regulate NRF2-associated epigenetic mechanisms. This review provides a better understanding of strategies to target NRF2 to protect against DM-related cardiac and vascular complications.

Lycium barbarum polysaccharide (LBP) inhibits palmitic acid (PA)-induced MC3T3-E1 cell apoptosis by regulating miR-200b-3p/Chrdl1/PPARγ

Background

Obesity is closely related to osteoporosis. Lycium barbarum polysaccharides (LBPs) have anti-osteoporosis activity.

Objective

This study aimed to explore the role of LBPs in palmitic acid (PA)-induced osteoblast apoptosis.

Methods

The microarray data set GSE37676 was downloaded from Gene Expression Ominibus (GEO) database. Top 300 differentially expressed genes (DEGs) were used to construct a protein–protein interaction (PPI) network based on STRING database, and significant modules were analyzed and their key genes were screened by using Cytoscape software. COEXPEDIA database showed that there was co-expression between Chrdl1 and peroxisome proliferator-activated receptor (PPARγ). MC3T3-E1 cells were treated with 100–500 μg/mL of PA. Reverse transcription polymerase chain reaction (RT-PCR) and western blot assays were used to detect mRNA and protein levels. Cell Counting Kit-8 (CCK-8) assay and flow cytometry were used to detect cell viability and cell apoptosis.

Results

Chrdl1 was the key gene from the most significant module and downregulation in MC3T3-E1 cells treated with PA. MicroRNA miR-200b-3p and PPARγ were significantly upregulated among PA-treated MC3T3-E1 cells. The results of luciferase reporter gene assay showed that miR-200b-3p targeted Chrdl1 3’-UTR. Over-expressing miR-200b-3p promoted PA-induced cell apoptosis and inhibited cell viability. After pre-treating cells with PA and LBP, MC3T3-E1 cell apoptosis rate was relatively lower than that of mimics+PA₂₀₀ group. Chrdl1 inhibition partly reversed miR-200b-3p effect on inhibiting apoptosis among MC3T3-E1 cells pre-treated with LBP and PA. Decreased C CASP3, PPARγ and increased Chrdl1 by miR-200b-3p inhibition were partly reversed by Chrdl1 inhibition.

Conclusions

LBPs inhibit PA-induced MC3T3-E1 cell apoptosis by mainly decreasing miR-200b-3p to upregulate Chrdl1, but miR-200b-3p/Chrdl1/PPARγ is not the only mechanism for LBPs protecting osteoblasts from PA.