Effect of Low Molecular Weight Oligopeptides Isolated from Sea Cucumber on Diabetic Wound Healing in db/db Mice

Research progress on the chemical components and biological activities of sea cucumber polypeptides

Owing to their unique physical and chemical properties and remarkable biological activities, marine biological resources are emerging as important sources of raw materials for producing health products, food, and cosmetics. Collagen accounts for approximately 70% of the sea cucumber body wall, and its hydrolysis produces small-molecule collagen polypeptides with diverse biological functions, such as anticancer, antihypertensive, immune-enhancing, memory-enhancing, and cartilage tissue repairing effects. Notably, the potential of sea cucumber polypeptides in combination with anticancer therapy has garnered considerable attention. Determining the composition and structure of sea cucumber polypeptides and exploring their structure-activity relationships will aid in obtaining an in-depth understanding of their diverse biological activities and provide scientific insights for the development and utilization of these polypeptides. Therefore, this review focuses on the amino acid structures and activities of sea cucumber polypeptides of varying molecular weights. This study also provides an overview of the biological activities of various sea cucumber polypeptides and aims to establish a scientific basis for their development.

Preparation of Nanoemulsions with Low-Molecular-Weight Collagen Peptides from Sturgeon Fish Skin and Evaluation of Anti-Diabetic and Wound-Healing Effects in Mice

This study aims to isolate collagen peptides from waste sturgeon fish skin, and prepare nanoemulsions for studying their anti-diabetic and wound-healing effects in mice. Collagen peptides were extracted and purified by acetic acid with sonication, followed by two-stage hydrolysis with 0.1% pepsin and 5% flavourzyme, and ultrafiltration with 500 Da molecular weight (MW) cut-off dialysis membrane. Animal experiments were performed with collagen peptides obtained by pepsin hydrolysis (37 kDa) and pepsin plus flavourzyme hydrolysis (728 Da) as well as their nanoemulsions prepared at two different doses (100 and 300 mg/kg/day). The mean particle size of low-MW and low-dose nanoemulsion, low-MW and high-dose nanoemulsion, high-MW and low-dose nanoemulsion and high-MW and high-dose nanoemulsion was, respectively, 16.9, 15.3, 28.1 and 24.2 nm, the polydispersity index was 0.198, 0.215, 0.231 and 0.222 and zeta potential was -61.2, -63.0, -41.4 and -42.7 mV. These nanoemulsions were highly stable over a 90-day storage period (4 °C and 25 °C) and heating at 40-100 °C (0.5-2 h). Experiments in mice revealed that the low-MW and high-dose nanoemulsion was the most effective in decreasing fasting blood glucose (46.75%) and increasing wound-healing area (95.53%). Collectively, the sturgeon fish skin collagen peptide-based nanoemulsion is promising for development into a health food or wound-healing drug.

The Effect of Rainbow Trout (Oncorhynchus mykiss) Collagen Incorporated with Exo-Polysaccharides Derived from Rhodotorula mucilaginosa sp. on Burn Healing

Burn is one of the physically debilitating injuries that can be potentially fatal; therefore, providing appropriate coverage in order to reduce possible mortality risk and accelerate wound healing is mandatory. In this study, collagen/exo-polysaccharide (Col/EPS 1-3%) scaffolds are synthesized from rainbow trout (Oncorhynchus mykiss) skins incorporated with Rhodotorula mucilaginosa sp. GUMS16, respectively, for promoting Grade 3 burn wound healing. Physicochemical characterizations and, consequently, biological properties of the Col/EPS scaffolds are tested. The results show that the presence of EPS does not affect the minimum porosity dimensions, while raising the EPS amount significantly reduces the maximum porosity dimensions. Thermogravimetric analysis (TGA), FTIR, and tensile property results confirm the successful incorporation of the EPS into Col scaffolds. Furthermore,the biological results show that the increasing EPS does not affect Col biodegradability and cell viability, and the use of Col/EPS 1% on rat models displays a faster healing rate. Finally, histopathological examination reveals that the Col/EPS 1% treatment accelerates wound healing, through greater re-epithelialization and dermal remodeling, more abundant fibroblast cells and Col accumulation. These findings suggest that Col/EPS 1% promotes dermal wound healing via antioxidant and anti-inflammatory activities, which can be a potential medical process in the treatment of burn wounds.

Oral administration of sea cucumber (Stichopus japonicus) protein exerts wound healing effects via the PI3K/AKT/mTOR signaling pathway

This study aimed to investigate the effect of the oral administration of sea cucumber protein (SCP) on wound healing. SCP was isolated and purified from the body wall of Stichopus japonicus. A mouse skin incision model was operated on to evaluate the wound repair effect of SCP. The histological changes in the skin at the wound sites of BALB/c mice were observed by staining with haematoxylin and eosin (H&E) and Masson's trichrome. The enzyme-linked immunosorbent assay (ELISA) was used to analyze the expression of inflammatory cytokines in BALB/c mice. The boost cell migration ability was detected by a scratch assay after HaCaT cells were cultured with digested SCP (dSCP). Western blotting and RT-PCR assays were performed to determine the mechanism of SCP promoting wound healing. As a result, the wound healing rate in the SCP high dose group was 1.3-fold, compared to that in the blank group on day 14. Also, increased epidermal thickness and 1.79-fold collagen deposition contrasted with the blank group. Additionally, SCP could up-regulate the levels of pro-inflammatory factors (IL-1β, IL-6, TNF-α) from day 3 to 7 firstly and decreased from day 7 to 14. IL-8 expression continuously decreased while the level of anti-inflammatory factor (IL-10) increased during the healing stage. Furthermore, the cell closure area reached 67% after being treated with 50 μg mL^-1 of dSCP for 48 h. Cell proliferation was associated with the dSCP-activated PI3K/AKT/mTOR pathway. Taken together, SCP can be orally used as an effective agent for wound repair.

Effect of Different Collagen on Anterior Cruciate Ligament Transection and Medial Meniscectomy-Induced Osteoarthritis Male Rats

Osteoarthritis (OA) is a common type of arthritis characterized by degeneration of the articular cartilage and joint dysfunction. Various pharmacological and non-pharmacological techniques have been used to manage these diseases. Due to the diverse therapeutic properties of marine collagen, it has received considerable attention in its pharmacological application. Thus, the purpose of this study was to compare the efficacy of jellyfish collagen, collagen peptide, other sources of marine collagen, and glycine in treating OA. In the OA rat model, an anterior cruciate ligament transection combined with medial meniscectomy surgery (ACLT + MMx) was used to induce osteoarthritis in rats. Two weeks before surgery, male Sprague-Dawley rats were fed a chow-fat diet. After 6 weeks of treatment with collagen, collagen peptide, and glycine, the results show that they could inhibit the production of proinflammatory cytokines and their derivatives, such as COX-2, MMP-13, and CTX-II levels; therefore, it can attenuate cartilage degradation. Moreover, collagen peptides can promote the synthesis of collagen type II in cartilage. These results demonstrate that collagen and glycine have been shown to have protective properties against OA cartilage degradation. In contrast, collagen peptides have been shown to show cartilage regeneration but less protective properties. Jellyfish collagen peptide at a dose of 5 mg/kg b. w. has the most significant potential for treating OA because it protects and regenerates cartilage in the knee.

Production of Bioactive Peptides from Sea Cucumber and Its Potential Health Benefits: A Comprehensive Review

Bioactive peptides from food have been widely studied due to their potential applications as functional foods and pharmaceuticals. Sea cucumber, a traditional tonic food, is characterized by high protein and low fat, thereby substrates are being studied to release sea cucumber peptides (SCPs). Although recent studies have shown that SCPs have various bioactive functions, there is no literature reviewing the development status of SCPs. In this review, we summarized the production of SCPs, including their purification and identification, then mainly focused on the comprehensive potential health benefits of SCP in vivo and in vitro, and finally discussed the challenge facing the development of SCPs. We found that SCPs have well-documented health benefits due to their antioxidation, anti-diabetes, ACE inhibitory, immunomodulatory, anti-cancer, anti-fatigue, anti-aging, neuroprotection, micromineral-chelating, etc. However, the structure-activity relationships of SCPs and the functional molecular mechanisms underlying their regulation in vivo need further investigation. Research on the safety of SCP and its potential regulation mechanism will contribute to transferring these findings into commercial applications. Hopefully, this review could promote the development and application of SCPs in further investigation and commercialization.

Evaluation of Wound Healing Activity of Sea Cucumber Holothuria parva Hydroalcoholic Extract in Rat

A significant challenge in biomedicine is the development of Biomaterials with the potential to accelerate wound healing. The aim of this study was to investigate the effect of the gel prepared from sea cucumber on wound healing in rats. Full-thickness wounds were created in male rats divided into five experimental groups, negative control (NC), positive control (PC), and treatments. The NC and PC groups received respectively gel base and phenytoin cream 1%. Treatment groups were treated topically by gels of 1%, 3%, and 5% Holothuria parva extract (HPE) in the gel base. The rats were sacrificed on days 7, 14, and 21. Pathological reports revealed the proliferation of keratinocytes in the borders of the wound in treatment groups and controls. Formation of granulation tissue was seen on day 7 in treatment groups, collagen fibers in granulation tissue were randomly organized, and the rate of fibroblast decreased. Results showed that there were statistically significant differences in wound contraction between all groups in comparison to the NC group (P < .05) on day 8. It was concluded that the 1% HPE gel has a good potential for promoting wound healing. [Formula: see text].

Preparation and Evaluation of the Curative Effect of Blue Shark (Prionace glauca) Skin Collagen Composite Gel in a Rat Oral Ulcers Model

Objective: To evaluate the curative effect of blue shark skin collagen composite gel on oral mucosal ulcer using the rat oral ulcers model stimulated by glacial acetic acid. Methods: Collagen from blue shark skin was isolated and physiochemically characterized by FTIR, SDS-PAGE and scanning electron microscopy (SEM). Seventy standard male rats were divided into seven groups. The surface and the area of the ulcer were observed and calculated daily. After 12 days of administration, rats in the model group and the control group were killed and the ulcer and surrounding tissues were cut to pieces about one mm3 size. The specimens were stained with 10% formalin solution, paraffinembedded sections, HE staining and light microscope were used to observe the histopathological changes in ulcer tissues. Results: The high-dose group had the fastest ulcer healing effects after 12 days of treatment with blue shark skin collagen composite gel. The composite gel was found to significantly accelerate the healing of oral ulcers in a dose-dependent manner. Conclusion: The blue shark skin collagen composite gel in this study may be a good biomedical material candidate for the treatment of oral ulcers in the near future. Potential of other marine fish skin collagen comples on healing oral ulcers should be also considered.

Animal by-products collagen and derived peptide, as important components of innovative sustainable food systems-a comprehensive review

In 2020, the world's food crisis and health industry ushered into a real outbreak. On one side, there were natural disasters such as the novel coronavirus (2019-nCoV), desert locusts, floods, and droughts exacerbating the world food crisis, while on the other side, the social development and changes in lifestyles prompted the health industry to gradually shift from a traditional medical model to a new pattern of prevention, treatment, and nourishment. Therefore, this article reviews animal by-products collagen and derived peptide, as important components of innovative sustainable food systems. The review also considered the preparation, identification, and characterization of animal by-product collagen and collagen peptides as well as their impacts on the food system (including food processing, packaging, preservation, and functional foods). Finally, the application and research progress of animal by-product collagen and peptide in the food system along with the future development trend were discussed. This knowledge would be of great significance for a comprehensive understanding of animal by-product collagen and collagen peptides and would encourage the use of collagen in food processing, preservation, and functional foods.

Antidepressant-like Effects of Degraded Porphyran Isolated from Porphyra haitanensis

INTRODUCTION

Degraded porphyran is a bioactive polysaccharide extracted from Porphyra haitanensis (P. haitanensis). According to the previous studies, it produced anti-inflammatory activity, but little is known about its effects on depression.

METHODS AND RESULTS

As inflammation is one of the critical factors involved in the development of depression, this study aims to elucidate the potential antidepressant-like effects of degraded porphyran. The results show that acute porphyran treatment decreased the immobility time in despair tests. In addition, subchronic porphyran administration reverses depressive-like behaviors in lipopolysaccharide (LPS)-treated mice. Meanwhile, porphyran inhibits NF-κB/NLRP3 signaling, proinflammatory cytokine release, and microglial activation in the hippocampus. Moreover, chronic porphyran treatment activates hippocampal brain derived neurotrophic factor (BDNF)/TrkB/ERK/CREB signaling pathway in chronic unpredictable mild stress (CUMS) in mice. As a result, neurogenesis and spinogenesis are maintained.

CONCLUSIONS

The findings of the present study indicate that degraded porphyran intake provides a potential strategy for depression treatment, which is mediated by the inhibition of neuroinflammation and the enhancement of neurogenesis and spinogenesis in the central nervous systems.

Effect of bovine bone collagen oligopeptides on wound healing in mice

Impaired wound healing often brings a set of problems in clinical practice. This study aimed to observe the wound healing potential of bovine bone collagen oligopeptides (BCOP) in mice. After an operation, mice in BCOP-treated groups were given intragastric administration of BCOP, while others were administered vehicle. Mice were sacrificed at different points. The wound healing condition and the tensile strength were observed, serum biochemical indexes and mRNA expression of level of related genes were measured. Compared with the normal control group, albumin (ALB), prealbumin (PA), transferrin (TRF), hydroxyproline (Hyp) levels and tension strength in the BCOP-treated groups increased significantly (p < 0.05). A pathological report showed that neutrophil granulocyte in the BCOP-treated groups decreased, while blood capillary and fibroblasts increased. The levels of serum inflammation indexes like interleukin (IL)-8, tumor necrosis factor (TNF)-α, chemokine (C-C motif) ligand 2 (CCL2) and C-reactive protein (CRP) significantly decreased in full-thickness incision model, whereas increased in full-thickness excision model (p < 0.05). Furthermore, IL-10, stromal cell-derived factor-1 alpha (SDF-1α) levels and the mRNA expression of vascular endothelial growth factor (VEGF) significantly increased in both models (p < 0.05). These results suggested that oral administration of BCOP could promote wound healing in mice.

Tilapia Skin Peptides Ameliorate Diabetic Nephropathy in STZ-Induced Diabetic Rats and HG-Induced GMCs by Improving Mitochondrial Dysfunction

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes, and mitochondrial dysfunction has been observed in the kidneys of diabetic patients. Tilapia skin peptides (TSPs) are mixtures of small-molecular-weight peptides derived from tilapia skin. Rising evidence suggests that bioactive peptides from marine sources are beneficial for DN. This study aimed to investigate whether TSPs can alleviate the pathological progress in experimental DN by improving mitochondrial dysfunction through the activation of Bnip3/Nix signaling. In the current study, TSPs treatment alleviated the metabolic parameters and renal morphology in streptozotocin-induced diabetic rats. Additionally, TSPs treatment significantly activated Bnip3/Nix signaling and improved the mitochondrial morphology, reversed the over-production of mitochondrial superoxide and cellular reactive oxygen species and the decreased mitochondrial membrane potential, thereby inhibiting the expressions of fibronectin, collagen IV and intercellular cell adhesion molecule-1 in glomerular mesangial cells induced by high glucose. Collectively, our results suggest that TSPs show the renoprotective effect on DN by improving mitochondrial dysfunction, and they can be a potential therapeutic strategy for DN.

Safety of radiotherapy for hemodialysis patients with cancer

BACKGROUND

The number of hemodialysis (HD) patients is increasing worldwide, and they are at a higher risk of cancer than the general population. Because HD patients are more likely to have inflammation, radiotherapy (RT)-induced adverse effects (AEs) are theoretically expected to be worse for HD patients. Since only a few reports have been published on this subject, we aimed to evaluate the tolerability of RT in HD patients.

METHODS

We retrospectively analyzed AEs related to RT for HD patients. Our study included patients from three institutions treated between January 2007 and July 2017. The patient eligibility criteria were (i) receipt of maintenance HD 2-3 times per week for end-stage renal disease prior to the start of RT and (ii) pathologically confirmed malignancies. The endpoints were acute and late non-hematologic AEs.

RESULTS

The study included 56 patients. The most common histology was head and neck cancer (23%), followed by lung cancer (14%) and prostate cancer (11%). The median radiation dose was 60 (range, 12-93.8) Gy at an equivalent dose in 2-Gy fractions (EQD2). The RT completion rate was 96%. Patients had a median follow-up period after RT of 9.1 (range 0.5-98.1) months. Grade 3 or worse acute and late AEs were noted in 6 (11%) and 3 (7%) patients, respectively. In the acute phase, 2 patients had grade 5 AEs, both of which were infections.

CONCLUSION

Our results suggest that RT for HD patients is clinically tolerable. However, some patients can experience severe infections related to treatment.

Effect of Oral Administration of Active Peptides of Pinctada Martensii on the Repair of Skin Wounds

Skin wound healing, especially chronic wound healing, is a common challenging clinical problem. It is urgent to broaden the sources of bioactive substances that can safely and efficiently promote skin wound healing. This study aimed to observe the effects of active peptides (APs) of the mantle of Pinctada martensii on wound healing. After physicochemical analysis of amino acids and mass spectrometry of APs, the effect of APs on promoting healing was studied through a whole cortex wound model on the back of mice for 18 consecutive days. The results showed that APs consisted of polypeptides with molecular weights in the range 302.17–2936.43 Da. The content of polypeptides containing 2–15 amino acids accounted for 73.87%, and the hydrophobic amino acids accounted for 56.51%. Results of in vitro experimentation showed that mice in APs-L group which were fed a low dose of APs (0.5 g/kg bw) had a shortened epithelialization time due to a shortening inflammatory period (p < 0.05). Mechanistically, this relied on its specific ability to promote the proliferation of CD31, FGF and EGF which accelerated the percentage of wound closure. Moreover, the APs-L group mice had enhanced collagen synthesis and increased type III collagen content in their wounds through a TGF-β/Smad signaling pathway (p > 0.05). Consequently, scar formation was inhibited and wound healing efficiency was significantly improved. These results show that the APs of Pinctada martensii promote dermal wound healing in mice and have tremendous potential for development and utilization in skin wound healing.

Marine Collagen Peptides Promote Cell Proliferation of NIH-3T3 Fibroblasts via NF-κB Signaling Pathway

Marine collagen peptides (MCPs) with the ability to promote cell proliferation and migration were obtained from the skin of Nibea japonica. The purpose of MCPs isolation was an attempt to convert the by-products of the marine product processing industry to high value-added items. MCPs were observed to contain many polypeptides with molecular weights ≤ 10 kDa and most amino acid residues were hydrophilic. MCPs (0.25–10 mg/mL) also exhibited 2, 2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, superoxide anion, and 2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activities. Furthermore, MCPs promoted the proliferation of NIH-3T3 cells. In vitro scratch assays indicated that MCPs significantly enhanced the scratch closure rate and promoted the migration of NIH-3T3 cells. To further determine the signaling mechanism of MCPs, western blotting was used to study the expression levels of nuclear factor kappa-B (NF-κB) p65, IκB kinase α (IKKα), and IκB kinase β (IKKβ) proteins of the NF-κB signaling pathway. Our results indicated protein levels of NF-κB p65, IKKα and IKKβ increased in MCPs-treated NIH-3T3 cells. In addition, MCPs increased the expression of epidermal growth factor (EGF), fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF-β) in NIH-3T3 cells. Therefore, MCPs, a by-product of N. japonica, exhibited potential wound healing abilities in vitro.