Skin aging occurs inevitably as a natural result of physiological changes over time. In particular, solar exposure of the skin accounts for up to 90% of skin damage. Numerous studies have examined the ability of dietary constituents to prevent skin aging, and recent research has emphasized the role of functional probiotics in intestinal function and skin aging. However, the mechanism of the interactions between aging and probiotics has not been elucidated yet. The aim of this study was to determine the role of exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) identified as Lactobacillus plantarum HY7714 in regulating tight junctions in intestinal epithelial cells and increasing moisture retention in human dermal fibroblasts cells. We observed that HY7714 EPS controlled intestinal tight junctions in Caco-2 cells by upregulating the genes encoding occludin-1 (OCL-1) and zonula occluden-1 (ZO-1). In addition, HY7714 EPS effectively improved UVB-induced cytotoxicity and hydration capacity in HS68 cells by downregulating production of metalloproteinases (MMPs) and reactive oxygen species (ROS). In summary, HY7714 EPS is an effective anti-aging molecule in skin and may have therapeutic potential against skin diseases and UVB-induced damage. Therefore, HY7714 EPS serves as a functional substance in skin–gut axis communication.

Despite increasing research on the gut-skin axis, there is a lack of comprehensive studies on the improvement of skin health through the regulation of the intestinal condition in humans. In this study, we investigated the benefits of Lactobacillus plantarum HY7714 (HY7714) consumption on skin health through its modulatory effects on the intestine and ensuing immune responses. HY7714 consumption led to differences in bacterial abundances from phylum to genus level, including increases in Actinobacteria followed by Bifidobacterium and a decrease in Proteobacteria. Additionally, HY7714 significantly ameliorated inflammation by reducing matrix metallopeptidases (MMP-2 and MMP-9), zonulin, and calprotectin in plasma, all of which are related to skin and intestinal permeability. Furthermore, RNA-seq analysis revealed its efficacy at restoring the integrity of the gut barrier by regulating gene expression associated with the extracellular matrix and immunity. This was evident by the upregulation of IGFBP5, SERPINE1, EFEMP1, COL6A3, and SEMA3B and downregulation of MT2A, MT1E, MT1X, MT1G, and MT1F between TNF- α and TNF- α plus HY7714 treated Caco-2 cells. These results propose the potential mechanistic role of HY7714 on skin health by the regulation of the gut condition.

Inflammatory bowel disease (IBD), a chronic condition that causes persistent inflammation in the digestive system, is closely associated with the intestinal microbiome. Here, we evaluated the effects of Lactiplantibacillus plantarum HY7718 (HY7718) on IBD symptoms in mice with dextran sulfate sodium (DSS)-induced colitis. Oral administration of HY7718 led to significant improvement in the disease activity index score and the histological index, as well as preventing weight loss, in model mice. HY7718 upregulated the expression of intestinal tight junction (TJ)-related genes and downregulated the expression of genes encoding pro-inflammatory cytokines and genes involved in the TLR/MyD88/NF-κB signaling pathway. Additionally, HY7718 reduced the blood levels of pro-inflammatory cytokines, as well as reversing DSS-induced changes to the composition of the intestinal microbiome. HY7718 also increased the percentage of beneficial bacteria (Lactiplantibacillus and Bifidobacterium), which correlated positively with the expression of intestinal TJ-related genes. Finally, HY7718 decreased the population of pathogens such as Escherichia, which correlated with IBD symptoms. The data suggest that HY7718 improves intestinal integrity in colitis model mice by regulating the expression of TJ proteins and inflammatory cytokines, as well as the composition of the intestinal microflora. Thus, L. plantarum HY7718 may be suitable as a functional supplement that improves IBD symptoms and gut health.

Epidemiological studies have shown that exposure to particulate matter (PM) is associated with adverse health effects. Inhalation of fine particulate matter (PM2.5) is associated with elevated pulmonary diseases. However, the molecular mechanism underlying the initiation of lung inflammation following inhalation is unclear. In this study, we investigated the beneficial effects of two probiotics, Lactobacillus casei HY2782 and Bifidobacterium lactis HY8002, against PM-induced pulmonary inflammation. Model mice were subjected to chronic exposure of PM2.5. The results showed that PM2.5 enhanced oxidative stress and led to Th2 cytokine responses in the mice. PM2.5-exposed mice were orally administered with HY2782 and HY8002 from the day of first exposure to the end point of the study. The results showed that HY2782 ameliorated PM 2.5 exposure-enhanced leukocyte migration and activation of proinflammatory cytokines. HY2782 and HY8002 also prevented exacerbation of eosinophil and neutrophil infiltration in the bronchoalveolar lavage fluid. HY2782 and HY8002 significantly increased scavenging of PM2.5-induced reactive oxygen species and activated superoxide dismutase and catalase activity in the blood. These results indicate that the probiotics HY2782 and HY8002 protect against PM-induced pulmonary inflammation.

Obesity is a major health issue worldwide, and is associated with many diseases including type 2 diabetes. In this study, we evaluated the anti-obesity effects of combinations of two lactic acid bacteria (LAB), Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032, and Cinnamomi Ramulus (CR) extract, and explored the mechanism through which they modulate gut microbiota using diet-induced obese mice. Male C57BL/6J mice were randomly divided into five groups that received a high-fat diet (HFD), HFD and LAB (HFD+LAB), HFD and CR extract (HFD+CR), HFD with LAB and CR extract (HFD+LAB+CR), or normal diet for 10 weeks. The mice in the HFD+LAB+CR group showed significant reductions in body weight gain, in particular epididymal fat and liver, blood leptin levels, and an increase in the levels of blood adiponectin. In addition, the LAB and CR extract altered the gut microbiota, mainly increasing the alpha diversity. These results demonstrate that a mixture of two LAB (Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032) and CR extracts alleviate HFD-induced obesity, and has potential of being used as a strategy for the treatment of obesity.

Bacterial vaginosis (BV) is caused by a microbial imbalance in the vaginal ecosystem, which causes genital discomfort and a variety of potential complications in women. This study validated the potential of Lactobacillus helveticus HY7801 as a probiotic to benefit vaginal health. In vivo, HY7801 reduced the number of Gardnerella vaginalis (GV) and pro-inflammatory cytokines in the vagina of GV-induced BV mice and ameliorated vaginal histological changes. In vitro, HY7801 exhibited positive resistance to simulated gastrointestinal conditions, showed excellent adherence ability to the female genital epithelium, and had high lactic acid and H₂O₂ production capacity. Furthermore, it was found that HY7801 can alleviate BV because it can suppress the expression of virulence factor genes of GV involved in epithelial cell adhesion and biofilm formation along with antibacterial activity against GV. These results indicate that HY7801 can be used as a promising probiotic strain for the maintenance of a healthy vaginal physiological state.