Skin Collagen Research Articles

Identification of a highly stable bioactive 3-hydroxyproline-containing tripeptide in human blood after collagen hydrolysate ingestion

There are increasing reports demonstrating high bioavailability of 4-hydroxyproline (4Hyp)-containing oligopeptides after oral ingestion of collagen hydrolysate and their bioactivity. In contrast, no study investigates the fate of another collagen-specific but minor amino acid, 3Hyp. Here, we identified Gly-3Hyp-4Hyp tripeptide in human blood at high concentrations, comparable to other 4Hyp-containing oligopeptides, after ingesting porcine skin collagen hydrolysate. Additionally, Gly-3Hyp-4Hyp uniquely maintained the maximum concentration until 4 h after the ingestion due to its exceptionally high resistance to peptidase/protease demonstrated by incubation with mouse plasma. In mice, oral administration of collagen hydrolysate prepared from bovine tendon, which contains a higher amount of 3Hyp, further increased blood Gly-3Hyp-4Hyp levels compared to that from bovine skin. Furthermore, Gly-3Hyp-4Hyp showed chemotactic activity on skin fibroblasts and promoted osteoblast differentiation. These results highlight the specific nature of the Gly-3Hyp-4Hyp tripeptide and its potential for health promotion and disease treatment.

A global approach to skin health and rejuvenation

Non-surgical facial and body rejuvenation continues to gain popularity globally as a low downtime option for restoring facial volume, improving skin tone, texture, collagen and hydration levels and reducing facial hyperpigmentation and photodamage while also offering enhancements through facial balance and symmetry using non-surgical interventions. It is important to take into consideration that today's modern patient is becoming more discerning and aware of various options available in the medical aesthetics world; however, it is important that providers employ a treatment algorithm for the safest enhancement and optimal outcomes. This article will provide a framework for the clinician to guide the patient in first laying the foundation for healthy skin practices, the gradual introduction of energy-based rejuvenation and, lastly, offering facial injectables only when necessary so as to promote a holistic, balanced and safer approach to optimal facial rejuvenation.

The protective effect of collagen peptides from bigeye tuna (Thunnus obesus) skin and bone to attenuate UVB-induced photoaging via MAPK and TGF-β signaling pathways

The aim of this study was to investigate the protective effect and mechanism of bigeye tuna (Thunnus obesus) skin collagen peptides (TSCP) and bone collagen peptides (TBCP) on skin photoaging. In UVB-damaged NIH/3T3 cells, TSCP and TBCP could effectively scavenge excessive reactive oxygen species, suppress mRNA and protein expression of MMP-1, and inhibit the decreased mRNA and protein expression of TGF-β1 and type I collagen. In the ICR mice model exposed to UVB, TSCP and TBCP could effectively improve moisture content, Hyp content and total antioxidant capacity level, activate TGF-β1 signaling pathway, and inhibit MAPK signaling pathway, thereby retarding UVB-induced skin photoaging. TSCP exhibited more excellent antioxidant activity, inhibited p-p38 activation and promoted TGF-β1 expression via TGF-β signaling pathway. By contrast, TBCP was more potent to down-regulate protein expression of p-ERK, p-JNK and MMP-1. The present work provides a theoretical basis for employment of collagen peptides to attenuate UVB-induced photoaging.

GLPGPSGEEGKR: Fe2+ chelating characterization and potential transport pathways for improving Fe2+ bioavailability in Caco-2 cells

We investigated the Fe2+ chelating properties and the mechanism of improving Fe2+ bioavailability of the Fe2+ chelating peptide (GLPGPSGEEGKR, peptide-G-R). Fe2+ was chelated with the carboxyl oxygen atom of the Glu-Glu residue in the form of monodentate and bidentate chelating mode. After chelation, peptide-G-R was folded and aggregated to form spherical particles with increasing particle size. Peptide-G-R could increase the Fe2+ transport/retention/uptake rate and the relative expression levels of divalent metal transporter 1 (DMT1) in the Caco-2 cells monolayer model. Peptide-G-R could reverse the inhibition of phytic acid on the Fe2+ utilization in the Caco-2 cells monolayer model. Molecular dynamics simulation showed that peptide-G-R interacted with DMT1 in the form of intermolecular hydrogen bonds. The transport mechanism of the peptide-G-R-Fe2+ complex included endocytosis (main pathway), paracellular pathway (auxiliary way), and DMT1 (potential pathway). Thus, peptide-G-R derived from tilapia skin collagen could be used as a dietary iron supplement.

Research on preparation technology of animal skin intrinsic multifunctional packaging material

High-end leather packaging material safe, environmentally friendly, and has a good market prospect. It is an interesting technology to solve the intrinsic functionalization of skin collagen packaging materials. Nano-Hydroxyapatite (HA) precursors solution with a specific 1.67 calcium to phosphorus ratio (Ca/P) were infiltrated into the three-dimensional collagen network matrix (3DCM) in situ growth based on goat skin pretreated with glutaraldehyde and the HAG-3DCM was obtained. After compression, a transparent film HAG-3DCM-was formed. Structural and functional characterization showed that the HAG-3DCM-CM film has good comprehensive performance, such as the tensile strength increased to 67 mPa from 28 mPa, the bending resistance increased from 5 cycles to 50 cycles and the swelling degree from 55% to 12%. HA disperses and fixes the three-dimensional collagen network matrix (3DCM) fibers, improves its stability against humidity and heat, and the thermal conductivity changed from 0.72 W/(K•m) to 0.65 W/(K•m). HAG-3DCM has a relatively high limiting oxygen index of 26.5%. This study demonstrates a new approach for preparing animal skin packaging materials with new application value.

Conception of an environmental friendly O/W cosmetic emulsion from microalgae

The development of eco-friendly cosmetic such as those from microalgaefor skin regeneration and collagen synthesis has gained a great interest worldwide. Accordingly, the potential of microalgae biomass as source of anti-aging cosmetic cream with high antioxidant activity has been investigated. Stabilities and sensory characteristics of cosmetic creams supplemented with Spirulina, Tetraselmis sp. and Dunaliella sp. at 0.5, 1.5and 2.5%, respectively, revealed a conservation of physico-chemical and preliminary stability properties of formulations. To analyze physico-chemical and textural parameters, accelerated stability study was evaluated under two thermal conditions (25 and 40 °C) during 90 days. Results showed that pH values of all formulations were within the limits of normal skin pH range under storage time at 25 and 40°C. During this period, the colored creams showed a significant changes of a* and b* indices, reflecting the instability of microalgae colors. Microalgae modified the textural characteristics of emulsions. The Tetraselmis sp. containing-cream had the lowest (P<0.05) values of hardness, springiness, and cohesiveness. The 0.5% Spirulina containing-cream had the best stableconsistency and adhesivenessundertime and temperature variations. It exhibited the best properties to be used for skin care products.Thanks to their high content in bioactive macromolecules,microalgae considerably improved the antioxidantactivity of the new formulated skin creams.

Alteration of collagen thermal denaturation, structural and the abrogation of allergenicity in eel skin induced by ohmic heating

This study aimed to evaluate the effect of ohmic heating (OH) on the thermal denaturation, structure, and allergenicity of collagen in fresh eel skin. The allergenicity of collagen decreased by approximately 70% at 50 °C as measured by simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and ELISA in vitro. SDS-PAGE analysis showed that the molecular weight of collagen did not decrease, but the band strength decreased with an increase in the processing temperature. FTIR and SEM analyses showed that the secondary structure and microstructure of collagen also changed. The water retention, dielectric properties and amino acid content of collagen also decreased with increasing temperature. Compared to water bath heating (WH), OH required significantly less time and energy and reduced the allergenicity of fish skin collagen through protein unfolding and secondary structure changes, thus potentially reducing the allergenicity of eel.

Identification of collagen 1α3 in teleost fish species and typical collision induced internal fragmentations.

In contrast to collagens 1α1 and 1α2, the more obscure collagen 1α3 is sparsely mentioned in literature. In skin collagen type 1 of teleosts (bony fish), however, the chain occurs in a heterotrimer together with collagens 1α1 and 1α2, which makes it one of the most abundant proteins in teleosts. As teleost fish species and gelatin (hydrolysate) prepared from their skin are a major source for food products and nutraceuticals, the goal of the study was to selectively identify collagen 1α3 in several fish species. Fish skin extracts and fish skin gelatins were analyzed using LC-MS. Depending on the amount of available genetic information different approaches were used to identify collagen 1α3. Additionally, collagen-specific collision induced internal fragmentations are discussed, which are important to consider during data analysis. Ultimately the presence of collagen 1α3 could be confirmed using LC-MS in multiple fish species.

Cryogenically structured gelatin-based hydrogel as a resorbable macroporous matrix for biomedical technologies

Objective: to investigate the biological properties of a matrix made of cryogenically structured hydrogel in the form of a macroporous gelatin sponge, as well as the possibility of creating cell-engineered constructs (CECs) on its basis. Materials and methods. The main components of the cryogenically structured hydrogel were gelatin (type A) obtained from porcine skin collagen, N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide, (EDC) and urea (all from Sigma-Aldrich, USA). Surface morphology was examined using scanning electron microscopy (SEM). The degree of swelling in water of the samples was determined by gravimetric method. Cytotoxicity was studied on NIH3T3, a fibroblast cell line isolated from a mouse, and on human adipose-derived mesenchymal stem/stromal cells (hAMSCs) using IncuCyte ZOOM (EssenBioscience, USA). The metabolic activity of hAMSCs was assessed using PrestoBlue™ reagents (Invitrogen™, USA). To create CECs, we used hAMSCs, human hepatocellular carcinoma cell line HepG2 or human umbilical vein endothelial cell lines EA.hy926. Albumin content in the culture medium was determined by enzyme immunoassay. Ammonia metabolism rate was assessed after 90 minutes of incubation with 1 mM ammonium chloride (Sigma-Aldrich, USA) diluted in a culture medium on day 15 of the experiment. Results. Obtaining a cryogenically structured hydrogel scaffold in the form of macroporous gelatin sponge included freezing an aqueous solution of a gelatin+urea mixture, removal of polycrystals of frozen solvent by lyophilization, extraction of urea with ethanol and treatment of the cryostructurate with an ethanol solution of EDC. Scanning electron microscopy identified three types of pores on the carrier surface: large (109 ± 17 μm), medium (39 ± 10 μm), and small (16 ± 6 μm). The degree of swelling in water of the matrix samples was 3.8 ± 0.2 g H2O per 1 g of dry polymer. The macroporous gelatin sponge as a part of CEC was found to have the ability to support adhesion and proliferation of hAMSCs, EA.hy926 and HepG2 for 28, 15 and 9 days, respectively. Albumin secretion and ammonia metabolism when HepG2 cells were cultured on the gelatin sponge were detected. Conclusion. The use of a matrix made from macroporous cryogenically structured gelatin-based hydrogel for tissue engineering products is shown to be promising using a cell-engineered liver construct as a case.

Does hyaluronidase injected in periocular area change skin ultrastructure?: Standardized in vitro analysis.

Treatment with hyaluronic acid (HA) fillers as a strategy for rejuvenation has experienced a significant growth in recent years, accompanied by a parallel increase in its complications, the treatment of which, such as hyaluronidase, we must be aware of. 14 patients (28 eyes) had indication for upper blepharoplasty surgery in the Hospital Universitario y Politécnico La Fe. After surgery, periocular skin of one eye of each patient was infiltrated with 300 U of hyaluronidase (14 cases) while the skin of the fellow eye was preserved untreated (14 controls). All samples were studied by the Pathology department, and finally, 6 variables (skin structure alteration, degeneration of elastic fibers, deposits, collagen fibers destructuring, inflammation, and other findings) were analyzed. No differences in skin structure, elastic fibers, and collagen dermal fibers were found between hyaluronidase-treated skin and controls. A significant association between ex vivo application of hyaluronidase in periocular skin and the presence of amorphous extracellular deposits within the dermis was found. Hyaluronidase applied ex vivo to periocular skin led to presence of deposits within the extracellular matrix compared to control eyelid skin but elastin and collagen dermis structure remained unaltered.

Dermal ultrasound measurements for bone quality assessment:An investigation of advanced glycation endproducts derived from confocal fluorescence microscopy.

Bone quality is increasingly being recognized in the assessment of fracture risk. Nonenzymatic collagen cross-linking with the accumulation of advanced glycation end products stiffens and embrittles collagen fibers thus increasing bone fragility. Echogenicity is anultrasound (US)parameter that provides information regarding the skin collagen structure. We hypothesized that both skin and bone collagen degrade in parallel fashion. Prospectively collected data of 110 patients undergoing posterior lumbar fusion was analyzed. Preoperative skin US measurements were performed in the lumbar region to assess dermal thickness and echogenicity. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and analyzed with confocal fluorescence microscopy for fluorescent advanced glycation endproducts (fAGEs). Pearson's correlation was calculated to examine relationships between (1)US and fAGEs, and (2) age and fAGEs stratified by sex. Multivariable linear regression analysis with adjustments for age, sex, body mass index(BMI), diabetes mellitus, and hemoglobin A1c (HbA1c) was used to investigate associations between US and fAGEs. One hundred and tenpatients (51.9% female, 61.6 years, BMI29.8 kg/m2 ) were included in the analysis. In the univariate analysis cortical and trabecular fAGEs decreased with age, but only in women (cortical: r = -0.32,p = 0.031; trabecular: r = -0.32;p = 0.031). After adjusting for age, sex, BMI, diabetes mellitus, and HbA1c, lower dermal (β = 1.01;p = 0.012) and subcutaneous (β = 1.01;p = 0.021) echogenicity increased with increasing cortical fAGEs and lower dermal echogenicity increased with increasing trabecular fAGEs (β = 1.01;p = 0.021). This is the first study demonstrating significant associations between skin US measurements and in vivo bone quality parameters in lumbar fusion patients. As a noninvasive assessment tool, skin US measurements might be incorporated into future practice to investigate bone quality in spine surgery patients.

Native human collagen type I provides a viable physiologically relevant alternative to xenogeneic sources for tissue engineering applications: A comparative in vitro and in vivo study.

Xenogeneic sources of collagen type I remain a common choice for regenerative medicine applications due to ease of availability. Human and animal sources have some similarities, but small variations in amino acid composition can influence the physical properties of collagen, cellular response, and tissue remodeling. The goal of this work is to compare human collagen type I-based hydrogels versus animal-derived collagen type I-based hydrogels, generated from commercially available products, for their physico-chemical properties and for tissue engineering and regenerative medicine applications. Specifically, we evaluated whether the native human skin type I collagen could be used in the three most common research applications of this protein: as a substrate for attachment and proliferation of conventional 2D cell culture; as a source of matrix for a 3D cell culture; and as a source of matrix for tissue engineering. Results showed that species and tissue specific variations of collagen sources significantly impact the physical, chemical, and biological properties of collagen hydrogels including gelation kinetics, swelling ratio, collagen fiber morphology, compressive modulus, stability, and metabolic activity of hMSCs. Tumor constructs formulated with human skin collagen showed a differential response to chemotherapy agents compared to rat tail collagen. Human skin collagen performed comparably to rat tail collagen and enabled assembly of perfused human vessels in vivo. Despite differences in collagen manufacturing methods and supplied forms, the results suggest that commercially available human collagen can be used in lieu of xenogeneic sources to create functional scaffolds, but not all sources of human collagen behave similarly. These factors must be considered in the development of 3D tissues for drug screening and regenerative medicine applications.

Free Radical Scavenging, Redox Balance and Wound Healing Activity of Bioactive Peptides Derived from Proteinase K-Assisted Hydrolysis of Hypophthalmichthys molitrix Skin Collagen.

Various protocols for enzymatic hydrolysis of fish by-products are increasingly tested to ensure value-added products with functional and biological properties important for food, cosmetic and medical applications. In addition, they attempt to minimize waste from industrial processing and environmental requirements. This study aims to establish an efficient protocol based on two-step enzymatic hydrolysis of freshwater fish skin and to evaluate the effect of resulting bioactive peptides on free radical scavenging, redox balance and regulation of fibroblast proliferation and migration. Pepsin-soluble collagen extracted from silver carp (Hypophthalmichthys molitrix) skin was hydrolyzed by proteinase K at specific sites under controlled conditions. The molecular mass of ultrafiltration permeate was determined by gradient electrophoresis and gel filtration chromatography. The biological activity of intermediate and small size bioactive peptides was evaluated in experimental models in vitro mimicking oxidative stress and skin wound conditions. Extracted fish collagen was hydrolysed using proteinase K, the most efficient enzyme for the cleavage of the primary structure of the molecule, as previously found in silico. Established optimal conditions increased the enzyme specificity and the process yield. Bioactive peptides exerted significantly higher scavenging activity on free stable radicals and hydroxyl radicals often found in vivo, compared to fish collagen. They stimulated fibroblast metabolism in a dose-dependent manner and up-regulated cell migration in a scratch wound model. Pretreatment of fibroblasts with induced oxidative stress using optimal concentrations of fish peptides prevented the increase of reactive oxygen species production. In conclusion, bioactive peptides from carp skin demonstrated valuable properties of maintaining redox balance and skin wound healing process improvement, which indicated further potential applications in the development of pharmaceutical and nutraceutical formulations. In this study the enzymatic hydrolysis was applied to isolated protein, in contrast to previous studies using waste tissue with variable composition. Recovered bioactive peptides acted not only as antioxidant agents, but also as regulators of oxidative stress and wound healing processes in skin cell models. Their nutritional and cosmetic application is recommended in novel formulations fighting skin ageing phenomena.

Aquaponics-Derived Tilapia Skin Collagen for Biomaterials Development.

Collagen is one of the most widely used biomaterials in health-related sectors. The industrial production of collagen mostly relies on its extraction from mammals, but several issues limited its use. In the last two decades, marine organisms attracted interest as safe, abundant, and alternative source for collagen extraction. In particular, the possibility to valorize the huge quantity of fish industry waste and byproducts as collagen source reinforced perception of fish collagen as eco-friendlier and particularly attractive in terms of profitability and cost-effectiveness. Especially fish byproducts from eco-sustainable aquaponics production allow for fish biomass with additional added value and controlled properties over time. Among fish species, Oreochromis niloticus is one of the most widely bred fish in large-scale aquaculture and aquaponics systems. In this work, type I collagen was extracted from aquaponics-raised Tilapia skin and characterized from a chemical, physical, mechanical, and biological point of view in comparison with a commercially available analog. Performed analysis confirmed that the proprietary process optimized for type I collagen extraction allowed to isolate pure native collagen and to preserve its native conformational structure. Preliminary cellular studies performed with mouse fibroblasts indicated its optimal biocompatibility. All data confirmed the eligibility of the extracted Tilapia-derived native type I collagen as a biomaterial for healthcare applications.

Restoring type VII collagen in skin

New therapeutic hope is emerging for people with the rare inherited blistering skin disease recessive dystrophic epidermolysis bullosa (RDEB). Gurevich etal.1 have reported early-phase clinical trial data evaluating a topical herpes simplex virus 1 vector to restore missing type VII collagen in RDEB skin and heal wounds.

Light-triggered on-site rapid formation of antibacterial hydrogel dressings for accelerated healing of infected wounds.

An optimal wound dressing can seal variously shaped wounds and provide a complete barrier to resist bacterial invasion; more importantly, the dressing can be stretched or compressed when the wounds are subjected to external forces and quickly return to its original state after the forces are withdrawn. Here, we designed dressings with light-triggered on-site rapid formation of antibacterial hydrogel for the accelerated healing of infected wounds. The pro-hydrogel, composed of acrylamide (AM) and dopamine-hyaluronic acid-ε-poly-l-lysine (DA-HA-EPL), was filled into the Vibrio vulnificus-infected wound. A 405-nm blue light was exerted on the wound to rapidly photopolymerize AM to its polymer, i.e., polyacrylamide (PAM). A hydrogel network of PAM/DA-HA-EPL immediately formed on site within several seconds to insulate the wound. PAM/DA-HA-EPL possessed adhesion performance to adapt to changes in wound morphologies due to external forces. Moreover, it presented high antibacterial ability due to the presence of EPL, in vitro biocompatibility and the ability to promote cell migration. Vibrio vulnificus-infected wounds were established on full-thickness mouse skin, and the hydrogel dressing exhibited high healing efficiency in terms of skin tissue regeneration, collagen deposition, and angiogenesis. PAM/DA-HA-EPL is a promising hydrogel dressing for the accelerated healing of infected wounds.

Snail mucin is a functional food ingredient for skin

• Exposure to UVB is a primary reason for skin aging, including wrinkle formation, skin dryness, and loss of elasticity. • Administration of snail mucin displayed anti-wrinkle activity by suppressing MMP-1/-13 expression with collagen restoration in mouse dorsal skin. • Skin hydration activity of snail mucin intake was confirmed by preventing water loss. • UVB-reduced skin elasticity was increased by oral administration of snail mucin in a dose-dependent manner. Recently, the interests about functional ingredients for skin has been increased. Snail mucin has been used to as cosmetic constituent for skin though, the potential of snail mucin for nutricosmetic ingredient has not been fully evaluated. Mucin is a biosynthesized macromolecule which can protect the external damage. The present study investigated the photoprotective effect of the snail mucin against ultraviolet B (UVB)-induced skin photoaging in an animal model. SKH-1 hairless male mice were fed with snail mucin or vehicle for 14 weeks with UVB exposure. Evaluation for the skin damage was analyzed skin replicas, epidermal thickness and collagen fiber integrity, and the moisture contents in the dermal tissue. As well as we studied the effect of snail mucin on the expression of matrix metalloproteinase (MMP)-1/13, hyaluronic acid synthase (HAS) and hyaluronidase (HYAL). The safety of intake of snail mucin is also evaluated in the liver, spleen, and liver damage enzyme level. The results showed that the depth of the wrinkles, relative moisture content, relative elasticity induced by UVB irradiation on the epidermis of mice were obviously improved by supplementation of snail mucin. Furthermore, snail mucin intake did not cause liver size change, body weight change, spleen enlargement, and liver damage enzyme. Taken together, oral administration of snail mucin improved UVB-induced photoaging properties such as wrinkle depth, moisture loss, and loss of elasticity on the skin with no toxicity. Therefore, we suggest potential of ingredient of nutricosmetics.

Autologous hematopoietic stem cell transplantation promotes connective tissue remodeling in systemic sclerosis patients

BackgroundAutologous hematopoietic stem cell transplantation (AHSCT) treats patients with severe and progressive systemic sclerosis (SSc). However, basic mechanisms associated with the therapeutic efficacy of the procedure are not entirely understood. We aimed to evaluate how AHSCT affects skin fibrosis in SSc patients.MethodsClinical data, serum, and skin samples from 39 SSc patients who underwent AHSCT were retrospectively evaluated. Skin biopsies were analyzed by immunohistochemistry with anti-MMP-1, -MMP-2, -MMP-3, -MMP-9, -TIMP-1, -α-SMA, -TGF-β, and -NF-κB p65 antibodies, and stained with hematoxylin and eosin and picrosirius red to assess skin thickness and collagen density, respectively. Serum samples were evaluated by Multiplex Assay for COL1A1, COL4A1, FGF-1, MMP-1, MMP-3, MMP-12, MMP-13, PDGF-AA, PDGF-BB, S100A9, and TIMP-1 levels and compared to healthy controls.ResultsAfter AHSCT, SSc patients showed clinical improvement in skin involvement, assessed by modified Rodnan’s skin score (mRSS). Histologically, collagen density and skin thickness decreased after AHSCT. Immunohistochemical analyses showed increased expression of MMP-2, MMP-3, MMP-9, and TIMP-1 after AHSCT, whereas expression of NF-κB p65 decreased. At baseline, serum levels of COL4A1 and S100A9 were higher than in healthy controls. Serum levels of S100A9 normalized after AHCST in SSc patients compared to controls. Serum levels of PDGF-AA, PDGF-BB, TIMP-1, and MMP-1 decreased, while COL1A1 increased after AHSCT in SSc patients. No changes were detected in MMP-3, MMP-12, MMP-13, and FGF-1 serum levels after AHSCT.ConclusionsOur results suggest that the therapeutic effects of AHSCT on skin fibrosis are related to changes in molecules associated with connective tissue maintenance and inflammation in SSc.

Exploration of the Molecular Mechanisms Underlying the Anti-Photoaging Effect of Limosilactobacillus fermentum XJC60.

Although lactic acid bacteria (LAB) were shown to be effective for preventing photoaging, the underlying molecular mechanisms have not been fully elucidated. Accordingly, we examined the anti-photoaging potential of 206 LAB isolates and discovered 32 strains with protective activities against UV-induced injury. All of these 32 LABs exhibited high levels of 2,2-diphenyl-picrylhydrazyl, as well as hydroxyl free radical scavenging ability (46.89–85.13% and 44.29–95.97%, respectively). Genome mining and metabonomic verification of the most effective strain, Limosilactobacillus fermentum XJC60, revealed that the anti-photoaging metabolite of LAB was nicotinamide (NAM; 18.50 mg/L in the cell-free serum of XJC60). Further analysis revealed that LAB-derived NAM could reduce reactive oxygen species levels by 70%, stabilize the mitochondrial membrane potential, and increase the NAD+/NADH ratio in UV-injured skin cells. Furthermore, LAB-derived NAM downregulated the transcript levels of matrix metalloproteinase (MMP)-1, MMP-3, interleukin (IL)-1β, IL-6, and IL-8 in skin cells. In vivo, XJC60 relieved imflammation and protected skin collagen fiber integrity in UV-injured Guinea pigs. Overall, our findings elucidate that LAB-derived NAM might protect skin from photoaging by stabilizing mitochondrial function, establishing a therotical foundation for the use of probiotics in the maintenance of skin health.

Fish collagen for skin wound healing: a systematic review in experimental animal studies.

Collagen extracted from fishes has been appearing as an alternative for commercial porcine and bovine collagen and it has been considered interesting especially for membrane manufacturing in tissue engineering. Despite the positive in vitro effects of fish collagen membranes, there is still no understanding of all the benefits that this natural biomaterial plays in the wound healing process, due to the lack of compilation of the results obtained in animal studies. In this sense, the purpose of this study was to perform a systematic review of the literature to examine the effects of fish collagen membranes for skin wound healing in experimental models of skin wound. The search was carried out according to the orientations of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), and the descriptors of the Medical Subject Headings (MeSH) were defined: "fish," collagen," "skin," and "in vivo". A total of 10 articles were retrieved from the databases PubMed and Scopus. After the elegibility analyses, this review covers the different origins of fish collagen reported in the different papers from the beginning of 2015 through the middle of 2021. The results were based mainly on histological analysis and macroscopic evaluation, and fish skin collagen was responsible for improving the wound healing rate and the process of reepithelization and collagen deposition. In conclusion, fish skin collagen has shown positive results in in vivo studies and may be a potential biomaterial in tissue engineering.