Lactic Acid Bacteria Improve the Photoprotective Effect via MAPK/AP-1/MMP Signaling Pathway on Skin Fibroblasts

Intestinal Fibrogenesis in Inflammatory Bowel Diseases: Exploring the Potential Role of Gut Microbiota Metabolites as Modulators

Fibrosis, sustained by the transformation of intestinal epithelial cells into fibroblasts (epithelial-to-mesenchymal transition, EMT), has been extensively studied in recent decades, with the molecular basis well-documented in various diseases, including inflammatory bowel diseases (IBDs). However, the factors influencing these pathways remain unclear. In recent years, the role of the gut microbiota in health and disease has garnered significant attention. Evidence suggests that an imbalanced or dysregulated microbiota, along with environmental and genetic factors, may contribute to the development of IBDs. Notably, microbes produce various metabolites that interact with host receptors and associated signaling pathways, influencing physiological and pathological changes. This review aims to present recent evidence highlighting the emerging role of the most studied metabolites as potential modulators of molecular pathways implicated in intestinal fibrosis and EMT in IBDs. These studies provide a deeper understanding of intestinal inflammation and fibrosis, elucidating the molecular basis of the microbiota role in IBDs, paving the way for future treatments.

The roles of gut microbiome and metabolites associated with skin photoaging in mice by intestinal flora sequencing and metabolomics

Photoaging of skin, a chronic disease, can produce the appearance changes and cancer lesions of skin. Therefore, it is of great significance to investigate the mechanisms and explore effective methods to treat the disorder. Gut microbiota and intestinal metabolisms have critical roles in a variety of diseases. However, their roles on photoaging of skin were not well tested. In the present work, the results showed that compared with control group, the levels of MDA, SOD and CAT associated with oxidative stress, the levels of COL I, CER, and HA associated with skin function, and the mRNA levels of IL-1β, IL-6, TNF-α associated with inflammation after long-term exposure to ultraviolet radiation in mice were significantly changed. Skin pathological tissue was also seriously damaged. The protein levels of AQP3 and FLG were significantly decreased. Ultraviolet exposure also promoted skin photoaging by activating TNFR1/TRAF2-mediated MAPK pathway, in which the protein levels of P38/P-P38, c-FOS/P-c-FOS, MMP1, TNFR1 and TRAF2 were significantly increased in model mice compared with control group. In fecal microbiota transplantation (FMT) experiment, we found that the intestinal microbiome of control mice alleviated skin photoaging via adjusting the protein levels of P38/P-P38, c-FOS/P-c-FOS, MMP1, TNFR1 and TRAF2. 16S rRNA sequencing found that 1639 intestinal bacteria were found, in which 15 bacteria including norank_f_Ruminococcaceae, Lachnospirac -eae_NK4A136_group, Lachnoclostridium, etc., were significantly different at the genus level. Untargeted GC-TOF/MS and UHPLC-MS/MS metabolomics showed 72 and 188 metabolites including taurine, ornithine, L-arginine, L-histidine, sucrose with significant differences compared with control group. Then, amino acid targeting assay showed 10 amino acids including L-ornithine, L-arginine and L-citrulline with higher levels in control group compared with model group. In addition, we also found that the variation of Lachnoclostridium abundance may regulate L-arginine metabolism to affect skin photoaging. Some intestinal bacteria and metabolites including amino acids may be closely related to skin photoaging, which should provide new methods to treat skin photoaging in the future.

Photoprotective Effects of Epigallocatechin Gallate on Ultraviolet-Induced Zebrafish and Human Skin Fibroblasts Cells

Background

The long-term exposure to ultraviolet radiation (UVR) raises oxidative stress and chronic inflammation levels, which in turn has a series of deleterious effects on skin health, such as sunburn, photoaging, and skin cancer. Hence, our study was determined to investigate the effects and mechanisms of epigallocatechin gallate (EGCG) in zebrafish and human skin fibroblasts (HSF) cells to alleviate ultraviolet-induced photoaging.

Methods

The 4 days postfertilization (dpf) zebrafish larvae and HSF cells were treated with 10 J/cm2 UVA + 30 mJ/cm2 UVB, or 25, or 50 μM EGCG for 72 hr. The indicators involving in oxidative stress, inflammatory, and photoaging were measured by the kits, ELISA Kits and western blot methods.

Results

EGCGs protect against UVR-induced skin damage in zebrafish and HSF cells. EGCG markedly decreased the reactive oxygen species (ROS), malondialdehyde, 8-OHdG levels, increased superoxide dismutase (SOD) activity, and significantly inhibited inflammatory factors levels including tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), interleukin-6 (IL-6) in zebrafish, and HSF cells irradiated with UVR. We found that EGCG could reduce UVR-induced p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation and effectively inhibited the activity of the transcriptional factor nuclear factor-κB (NF-κB), thereby reducing the protein-1 (AP-1), TNF-α, IL-1α, IL-6, and matrix metalloproteinase-1 (MMP-1) expressions, which are critical mediators of skin aging cascade causing the photoaging.

Conclusion

These results validate that EGCG for protection of photoaging in zebrafish and HSF cells induced by UVR, which is closely related to the regulation of p38 MAPK/NF-κB, AP-1 signaling pathway which relieve oxidative stress, inflammation, and collagen degradation.

Effects of Bacterial Lysates and Metabolites on Collagen Homeostasis in TNF-α-Challenged Human Dermal Fibroblasts

During skin aging, the production of extracellular matrix (ECM) proteins, such as type I collagen, decreases and the synthesis of ECM-degrading matrix metalloproteinases (MMPs) rises, leading to an imbalance in homeostasis and to wrinkle formation. In this study, we examined the effects of bacterial lysates and metabolites from three bifidobacteria and five lactobacilli on collagen homeostasis in human dermal fibroblasts during challenge with tumor necrosis factor alpha (TNF-α), modeling an inflammatory condition that damages the skin's structure. Antiaging properties were measured, based on fibroblast cell viability and confluence, amount of type I pro-collagen, ratio of MMP-1 to type I pro-collagen, cytokines, and growth factors. The TNF-α challenge increased the MMP-1/type I pro-collagen ratio and levels of proinflammatory cytokines, as expected. With the probiotics, differences were clearly dependent on bacterial species, strain, and form. In general, the lysates elicited less pronounced responses in the biomarkers. Of all strains, the Bifidobacterium animalis ssp. lactis strains Bl-04 and B420 best maintained type I pro-collagen production and the MMP-1/collagen type I ratio under no-challenge and challenge conditions. Metabolites that were produced by bifidobacteria, but not their lysates, reduced several proinflammatory cytokines (IL-6, IL-8, and TNF-α) during the challenge, whereas those from lactobacilli did not. These results indicate that B. animalis ssp. lactis-produced metabolites, especially those of strains Bl-04 and B420, could support collagen homeostasis in the skin.

Photoprotective and antigenotoxic properties of Cutibacterium acnes ecotypes native to terrestrial subsurface habitats

Actinobacteria are known to produce a variety of secondary metabolites with skin-protective properties. This study aimed to investigate the photoprotective and antigenotoxic properties against UVB of extracts obtained from Cutibacterium acnes strains. Bacterial growth was measured spectrophotometrically and the constant maximum growth rate (μ) value to each strain, were calculated. In vitro photoprotection efficacy was evaluated using in vitro indices such as sun protection factor (SPFespectrophotometric) and critical wavelength (λc). UVB-antigenotoxicity was also evaluated using the SOS Chromotest. Correlation analysis was used to examine the relationship between SPFespectrophotometric and extract concentration and the %GI estimates. Among the studied strains, one showed low (6.0 ≤ SPFespectrophotometric ≤ 14.9) and eight showed media (15.0 ≤ SPFespectrophotometric ≤ 29.9) UVB photoprotection efficacy. All of them resulted in broad-spectrum (UVA-UVB) photoprotection (λc > 370 nm). In total, two C. acnes ecotypes with different growth rates were evidenced, but the protective metabolites in the extracts were produced without the influence of growth rate. Photoprotective efficacy depended on the extract concentration and was correlated with antigenotoxicity. We demonstrated that C. acnes extracts can be used as sunscreen ingredients that reduce UVB-induced genotoxicity.