Degraded Sericin Significantly Regulates Blood Glucose Levels and Improves Impaired Liver Function in T2D Rats by Reducing Oxidative Stress

Oral Toxicity and Hypotensive Influence of Sericin-Derived Oligopeptides (SDOs) from Yellow Silk Cocoons of Bombyx mori in Rodent Studies

Sericin-derived oligopeptides (SDOs) from yellow silk cocoons exhibit antihypertensive and hypoglycemic properties in both in vitro and in vivo studies. This study investigated the acute toxicity of SDOs as a novel food for human consumption using female ICR mice and Wistar rats, as well as the chronic toxicity test on both sexes of Wistar rats. Clinical chemistry, hematology, and histopathological studies revealed that SDOs were safe for a single dose of 2000 mg kg-1 body weight (BW) and daily oral administration of 50, 100, and 200 mg kg-1 BW for six months. The chronic toxicity study additionally measured the rats' systolic blood pressure (SBP) and blood sugar monthly as they slowly aged. In the 2nd month for male rats and the 4th month for both sexes, SDOs had a significant hypotensive effect on Wistar rats' blood pressure, lowering it from 130 mmHg to a plateau at 110-115 mmHg. In contrast, the blood pressure of the control rats exceeded 140 mmHg after five months. Nonetheless, the hypoglycemic effect was not observed. Measurements of SBP and blood glucose in aged rats during chronic toxicity tests yielded insights beyond ordinary toxicity, including the health and fitness of the lab rats, perhaps resulting in novel discoveries or areas of study that justify the sacrifice of the animals' lives.

Transcriptomic screening of novel targets of sericin in human hepatocellular carcinoma cells

Sericin, a natural protein derived from Bombyx mori, is known to ameliorate liver tissue damage; however, its molecular mechanism remains unclear. Herein, we aimed to identify the possible novel targets of sericin in hepatocytes and related cellular pathways. RNA sequencing analysis indicated that a low dose of sericin resulted in 18 differentially expressed genes (DEGs) being upregulated and 68 DEGs being downregulated, while 61 DEGs were upregulated and 265 DEGs were downregulated in response to a high dose of sericin (FDR ≤ 0.05, fold change > 1.50). Functional analysis revealed that a low dose of sericin regulated pathways associated with the complement and coagulation cascade, metallothionine, and histone demethylate (HDMs), whereas a high dose of sericin was associated with pathways involved in lipid metabolism, mitogen-activated protein kinase (MAPK) signaling and autophagy. The gene network analysis highlighted twelve genes, A2M, SERPINA5, MT2A, MT1G, MT1E, ARID5B, POU2F1, APOB, TRAF6, HSPA8, FGFR1, and OGT, as novel targets of sericin. Network analysis of transcription factor activity revealed that sericin affects NFE2L2, TFAP2C, STAT1, GATA3, CREB1 and CEBPA. Additionally, the protective effects of sericin depended on the counterregulation of APOB, POU2F1, OGT, TRAF6, and HSPA5. These findings suggest that sericin exerts hepatoprotective effects through diverse pathways at different doses, providing novel potential targets for the treatment of liver diseases.

Sericin and melatonin mitigate diethylnitrosamine-instigated testicular impairment in mice: Implications of oxidative stress, spermatogenesis, steroidogenesis, and modulation of Nrf2/WT1/SF-1 signaling pathways

AIMS

This study aimed to investigate the therapeutic influence of combination therapy with sericin and melatonin on attenuating diethylnitrosamine (DEN)-instigated testicular dysfunction in mice and defining the molecular mechanisms involved in orchestrating redox signaling pathways and restoring spermatogenesis and steroidogenesis.

MATERIALS AND METHODS

Different groups of male Swiss albino mice were established and injected with respective drugs intraperitoneally. Semen analysis, hormonal assays, and oxidative stress biomarkers were evaluated. Additionally, melatonin and its receptors, WT1, SF-1, vimentin, Nrf2, and ANXA1 expressions were assessed. Histopathological and ultrastructural features of the testes were investigated by semithin, SEM, and TEM analyses.

KEY FINDINGS

Exposure to DEN exhibited pathophysiological consequences, including a remarkable increase in lipid peroxidation associated with substantial diminutions in SOD, CAT, GPx, GSH, GSH:GSSG, and GST. Furthermore, it disrupted spermatozoa integrity, testosterone, FSH, LH, melatonin, and its receptors (MT1 and MT2) levels, implying spermatogenesis dysfunction. By contrast, treatment with sericin and melatonin significantly restored these disturbances. Interestingly, the combination therapy of sericin and melatonin noticeably augmented the Nrf2, WT1, and SF-1 expressions compared to DEN-treated mice, deciphering the amelioration perceived in antioxidant defense and spermatogenesis inside cells. Furthermore, immunohistochemical detection of ANXA1 alongside histopathological and ultrastructural analyses revealed evident maintenance of testicular structures without discernible inflammation or anomalies in mice administered with sericin and melatonin compared to the DEN-treated group.

SIGNIFICANCE

Our findings highlighted that treatment with sericin and melatonin alleviated the testicular tissues in mice from oxidative stress and dysregulated spermatogenesis and steroidogenesis engendered by DEN.

Nature-Derived Polysaccharide-Based Composite Hydrogels for Promoting Wound Healing

Numerous innovative advancements in dressing technology for wound healing have emerged. Among the various types of wound dressings available, hydrogel dressings, structured with a three-dimensional network and composed of predominantly hydrophilic components, are widely used for wound care due to their remarkable capacity to absorb abundant wound exudate, maintain a moisture environment, provide soothing and cooling effects, and mimic the extracellular matrix. Composite hydrogel dressings, one of the evolved dressings, address the limitations of traditional hydrogel dressings by incorporating additional components, including particles, fibers, fabrics, or foams, within the hydrogels, effectively promoting wound treatment and healing. The added elements enhance the features or add specific functionalities of the dressings, such as sensitivity to external factors, adhesiveness, mechanical strength, control over the release of therapeutic agents, antioxidant and antimicrobial properties, and tissue regeneration behavior. They can be categorized as natural or synthetic based on the origin of the main components of the hydrogel network. This review focuses on recent research on developing natural polysaccharide-based composite hydrogel wound dressings. It explores their preparation and composition, the reinforcement materials integrated into hydrogels, and therapeutic agents. Furthermore, it discusses their features and the specific types of wounds where applied.

Sericin enhances ammonia detoxification by promotes urea cycle enzyme genes and activates hepatic autophagy in relation to CARD-9/MAPK pathway

Urea cycle is an important metabolic process that initiates in liver mitochondria and converts ammonia to urea. The impairment of ammonia detoxification, both primary and secondary causes, lead to hyperammonemia, a life-threatening condition affecting to the brain. Current treatments are not enough effective. In addition, our recent proteomics study in hypercholesterolemic rat model demonstrated that sericin enhances hepatic nitrogenous waste removal through carbamoyl-phosphate synthase 1 (CPS-1), aldehyde dehydrogenase-2 (ALDH-2), and uricase proteins. However, the underlining mechanisms regard to this property is not clarified yet. Therefore, the present study aims to examine the effect of sericin on urea cycle enzyme genes (CPS-1 and ornithine transcarbamylase; OTC) and proteins (mitogen-activated protein kinase; MAPK, caspase recruitment domain-containing protein 9; CARD-9, Microtubule-associated protein light chain 3; LC-3), which relate to urea production and liver homeostasis in hepatic cell line (HepG2) and hypercholesterolemic rat treated with or without sericin. qRT-PCR, immunohistochemistry, and electron microscopy techniques were performed. In vitro study determined that high dose of sericin at 1 mg/ml increased liver detoxification enzyme (Cytochrome P450 1A2; CYP1A2 and ALDH-2) and urea cycle enzyme (CPS-1 and OTC) genes. Both in HepG2 cell and rat liver mitochondria, sericin significantly downregulated CARD-9 (apoptotic protein) expression while upregulated MAPK (hepatic homeostasis protein) and LC-3 (autophagic protein) expressions. Hence, it might be concluded that sericin promotes ammonia detoxification by both increases urea cycle enzyme genes and enhances hepatic autophagy in associated with CARD-9/MAPK pathway (as shown by their own negative relationship). This study presents another beneficial property of sericin to develop an upcoming candidate for ammonia toxicity alleviation and liver function improvement.

Sericin from Fibroin-Deficient Silkworms Served as a Promising Resource for Biomedicine

Sericin, a fascinating natural biomaterial derived from silkworms, has received increasing interest in recent years for its unique bioactivity and high compatibility. Silkworms can be divided into wild-type or silk fibroin-deficient mutants according to whether they synthesize and secrete silk fibroin. Silk fibroin-deficient mutant silkworms and their cocoons are convenient for us to obtain diverse and high-quality sericin, which has been applicated in various fields such as cell culture, tissue engineering, drug delivery, and cosmetics. Here, we present an overview of our silkworm varieties resources, especially silk fibroin-deficient mutant silkworms. We optimized various extraction methods of sericin and summarized the characteristics and advantages of sericin. Finally, we developed and discussed a series of sericin-based biomaterials for promising applications for a diverse set of needs.

Effect of mussel polysaccharide on glucolipid metabolism and intestinal flora in type 2 diabetic mice

BACKGROUND

Type 2 diabetes (T2D) mellitus is a major metabolic disease, and its incidence and lethality have increased significantly in recent years, making it a serious threat to human health. Among numerous previous studies, polysaccharides have been shown to alleviate the adverse effects of T2D, but there are still problems such as insufficient analysis and poor understanding of the mechanisms by which polysaccharides, especially those of marine origin, regulate T2D.

METHODS

In this study, we used multiple allosteric approaches to further investigate the regulatory effects of mussel polysaccharides (MPs) on T2D and gut microbiota disorders in mice by identifying changes in genes, proteins, metabolites and target organs associated with glucolipid metabolism using an animal model of T2D fed with high-fat diets, and to explore the underlying molecular mechanisms.

RESULTS

After MP intervention, serum levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and high-density lipoprotein cholesterol (HDL-C) were up-regulated, and blood glucose and lipid levels were effectively reduced in T2D mice. Activation of signaling molecules related to the upstream and downstream of the insulin PI3K/Akt signaling pathway reduced hepatic insulin resistance. The relative abundance of short-chain fatty acid (SCFA)-producing bacteria (including Akkermansia, Siraeum Eubacterium and Allobaculum) increased and harmful desulfurizing Vibrio decreased. In addition, the levels of SCFAs were increased.

CONCLUSION

These results suggest that MP can increase SCFA levels by altering the abundance of intestinal flora, thereby activating the PI3K/Akt signaling pathway and exerting hypoglycemic effects. © 2023 Society of Chemical Industry.

Regulatory effect of sericin protein in inflammatory pathways; A comprehensive review

Sericin protein is a type of protein derived from silk cocoons. Sericin hydrogen bonds cause adhesion to the silk cocoon. This substance contains a large amount of serine amino acids in its structure. At first, the medicinal properties of this substance were unknown, but today many properties have been discovered for this substance. The unique properties of this substance have made it widely used in the pharmaceutical and cosmetic industries. The applications of Sericin in pharmacy are as follows. Sericin is used to repair wounds by producing collagen. Other uses for the drug include anti-diabetic, anti-cholesterol, metabolic modulator, anti-tumor, heart protection, antioxidant, antibacterial, wound healing, cell proliferation, UV protection, freezing, and skin moisturizing. The physicochemical properties of Sericin have attracted the attention of pharmacists and their widespread use in the production of drugs and treatment of diseases. One of the critical and unique properties of Sericin is its anti-inflammatory property. In this article, this property of Sericin is discussed in detail, and according to the experiments performed by pharmacists, this substance has shown a significant effect in eliminating inflammation. This study aimed to evaluate the impact of Sericin protein in relieving inflammation.

Silk sericin as building blocks of bioactive materials for advanced therapeutics

Silk sericin is a class of protein biopolymers produced by silkworms. Increasing attention has been paid to silk sericin for biomedical applications in the last decade, not only because of its excellent biocompatibility and biodegradability but also due to the pharmacological activities stemming from its unique amino acid compositions. In this review, the biological properties of silk sericin, including curing specific diseases and promoting tissue regeneration, as well as underlying mechanisms are summarized. We consider the antioxidant activity of silk sericin as a fundamental property, which could account for partial biological activities, despite the exact mechanisms of silk sericin's effect remaining unknown. Based on the reactive groups on silk sericin, approaches of bottom-up fabrication of silk sericin-based biomaterials are highlighted, including non-covalent interactions and chemical reactions (reduction, crosslinking, bioconjugation, and polymerization). We then briefly present the cutting-edge advances of silk sericin-based biomaterials applied in tissue engineering and drug delivery. The challenges of silk sericin-based biomaterials are proposed. With more bioactivities and underlying mechanisms of silk sericin uncovered, it is going to boost the therapeutic potential of silk sericin-based biomaterials.

Sustainable Prebiotic Dessert with Sericin Produced by Bombyx mori Worms

(1) Background: The processing of silk threads secreted by the silkworm Bombyx mori leads to large amounts of sericin as textile waste. Its biochemical and medical properties open a new perspective for its use in the food industry and its authorization as a new food ingredient in the European Union, by the European Commission and the European Food Safety Authority. (2) Methods: Experimental and physico–chemical analyzes were carried out to obtain a sustainable prebiotic dessert with low energy value, containing Sericin produced by Bombyx Mori, which does not contain sugar and can be consumed both by people who want a healthy diet and people who need food for special nutritional conditions, such as diabetes, dysphagia or inflammatory diseases. (3) Results: The sustainable jelly was made from depectinized apple juice, pectin, sericin, lactoferrin, stevia and pectin. This dessert is natural and can be certified organic and HALAL. (4) Conclusions: Sericin can be used in the manufacture of a very wide range of foods. Being a glycoprotein, it can also be used to obtain jelling foods with low energy value, including foods for patients with dysphagia. This represents an important sustainable resource of essential amino acids for the normal homeostasis of the human body.

The Protective Effect of Sericin on AML12 Cells Exposed to Oxidative Stress Damage in a High-Glucose Environment

Two types of sericin peptides with high molecular weight (HS) and low molecular weight (LS) were obtained by the green water boiling ultrasonic method and the Ca(OH)2 ultrasonic method, respectively. In this experiment, a high-glucose medium was used to simulate a high-glucose environment in the body, and appropriate concentrations of normal alpha mouse liver 12 (AML12) hepatocytes were exposed to a series of concentrations of HS and LS. The effects of the two sericin peptides on AML12 cells in a high-glucose environment were investigated in detail in terms of oxidative stress and inflammatory factor expression in cells. HS and LS-groups reduced the levels of oxidative stress, inflammation, and tumor necrosis factor (TNF), and the latter significantly reduced the levels of TNF-α, interleukin (IL)-6, and nuclear factor (NF)-κB in AML12 cells. Additionally, it significantly reduced the oxidative stress damage caused by the high-glucose environment compared with normal AML12 cells. These results indicate that sericin may be an antioxidant recovered from industrial waste, and has potential and for use in the reduction of environmental pollution and the development of functional foods with antioxidation and antihyperglycemic effect.

Investigation of the Repairing Effect and Mechanism of Oral Degraded Sericin on Liver Injury in Type II Diabetic Rats

In the sericulture and silk production industry, sericin is discharged in the degumming wastewater, resulting in a large amount of wasted natural protein and environmental pollution. This study investigated the effect of degraded sericin recovered by the Ca(OH)₂–ultrasound degumming method (a green process) on liver injury in T2D rats. After 4 weeks of dietary sericin supplementation, the liver masses and organ coefficients of the T2D rats improved compared with those of the model rats that were not fed sericin. Oral sericin activated the damaged PI3K/AKT/AMPK pathway to enhance glycogen synthesis, accelerate glycolysis, and inhibit gluconeogenesis. The protein expression levels of the inflammatory factors NF-κB, IL-6, and TNF-α in the T2D model group were up to two times higher than in the normal group. However, all three T2D groups that received oral sericin showed significant decreases in these factors to the level found in the normal group, indicating that inflammation in the body was significantly reduced. These results show that the sericin protein might improve glycogen synthesis, accelerate glycolysis, and inhibit gluconeogenesis by enhancing the anti-oxidation capability and reducing inflammatory reactions. Therefore, sericin recovered by Ca(OH)₂ degradation has potential use in the development of functional health foods that can lower blood sugar.

Enhancing the In Vitro Biological Activity of Degraded Silk Sericin and Its Analog Metabolites

Two sericins of high and low molecular weight (HS and LS) were prepared from commercial silkworm cocoon silk with a boiling water and Ca(OH)₂ solution with ultrasonic treatments, respectively. This study first investigated the release concentration of the two abovementioned sericins in simulated saliva, gastric juice, and intestinal juice (pH 6.8, 2.0, and 7.4, respectively) within 10 h. The results showed that the order of sericin release rate and its amount in the simulated environment was gastric juice > saliva > intestinal juice. Second, the molecular weights of both sericin metabolites formed by in vitro enzymatic degradation were lower than 15 kDa. The α-glucosidase inhibitory activities of both sericins and their analog metabolites were positively correlated with their concentrations. The IC₅₀ values of the HS- and LS-derived metabolites were 1.02 ± 0.12 mg/mL and 0.91 ± 0.15 mg/mL, respectively, which were five to seven times lower than those of both original sericins. The total antioxidant capacities and hydroxyl radical scavenging capacities of both metabolites were enhanced by one- to three-fold compared with HS and LS. These results indicate that both sericins, regardless of molecular size, have significantly enhanced antioxidant, superoxide free radical scavenging, and glycosidase inhibitory activities after simulated metabolism, and that LS is better than HS regardless of simulated digestion. These results confirm that sericin is important in the sustainable development and utilization of silk resources, especially the reduction in environmental pollution, and provides new ideas for the development of adjuvant treatments for diabetes and the development of foods with anti-hyperglycemic functions.