Inhibitory effects of 6'-sialyllactose on angiotensin II-induced proliferation, migration, and osteogenic switching in vascular smooth muscle cells

Vinpocetine, a phosphodiesterase 1 inhibitor, mitigates atopic dermatitis-like skin inflammation

Atopic dermatitis (AD) is the most common inflammatory pruritic skin disease worldwide, characterized by the infiltration of multiple pathogenic T lymphocytes and histological symptoms such as epidermal and dermal thickening. This study aims to investigate the effect of vinpocetine (Vinp; a phosphodiesterase 1 inhibitor) on a 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD-like model. DNCB (1%) was administered on day 1 in the AD model. Subsequently, from day 14 onward, mice in each group (Vinp-treated groups: 1 mg/kg and 2 mg/kg and dexamethasone- treated group: 2 mg/kg) were administered 100 µl of a specific drug daily, whereas 0.2% DNCB was administered every other day for 30 min over 14 days. The Vinp-treated groups showed improved Eczema Area and Severity Index scores and trans-epidermal water loss, indicating the efficacy of Vinp in improving AD and enhancing skin barrier function. Histological analysis further confirmed the reduction in hyperplasia of the epidermis and the infiltration of inflammatory cells, including macrophages, eosinophils, and mast cells, with Vinp treatment. Moreover, Vinp reduced serum concentrations of IgE, interleukin (IL)-6, IL-13, and monocyte chemotactic protein-1. The mRNA levels of IL-1β, IL-6, Thymic stromal lymphopoietin, and transforming growth factor-beta (TGF-β) were reduced by Vinp treatment. Reduction of TGF-β protein by Vinp in skin tissue was also observed. Collectively, our results underscore the effectiveness of Vinp in mitigating DNCB-induced AD by modulating the expression of various biomarkers. Consequently, Vinp is a promising therapeutic candidate for treating AD.

Potential biological functions and future perspectives of sialylated milk oligosaccharides

Sialyllactoses (SLs) primarily include sialylated human milk oligosaccharides (HMOs) and bovine milk oligosaccharides (BMOs). First, the safety assessment of 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL) revealed low toxicity in various animal models and human participants. SLs constitute a unique milk component, highlighting the essential nutrients and bioactive components crucial for infant development, along with numerous associated health benefits for various diseases. This review explores the safety, biosynthesis, and potential biological effects of SLs, with a specific focus on their influence across various physiological systems, including the gastrointestinal system, immune disorders, rare genetic disorders (such as GNE myopathy), cancers, neurological disorders, cardiovascular diseases, diverse cancers, and viral infections, thus indicating their therapeutic potential.

3'-Sialyllactose protects against LPS-induced endothelial dysfunction by inhibiting superoxide-mediated ERK1/2/STAT1 activation and HMGB1/RAGE axis

AIM

Endothelial hyperpermeability is an early stage of endothelial dysfunction associated with the progression and development of atherosclerosis. 3'-Sialyllactose (3'-SL) is the most abundant compound in human milk oligosaccharides, and it has the potential to regulate endothelial dysfunction. This study investigated the beneficial effects of 3'-SL on lipopolysaccharide (LPS)-induced endothelial dysfunction in vitro and in vivo.

MAIN METHODS

We established LPS-induced endothelial dysfunction models in both cultured bovine aortic endothelial cells (BAECs) and mouse models to determine the effects of 3'-SL. Western blotting, qRT-PCR analysis, immunofluorescence staining, and en face staining were employed to clarify underlying mechanisms. Superoxide production was measured by 2',7'-dichlorofluorescin diacetate, and dihydroethidium staining.

KEY FINDINGS

LPS significantly decreased cell viability, whereas 3'-SL treatment mitigated these effects via inhibiting ERK1/2 activation. Mechanistically, 3'-SL ameliorated LPS-induced ROS accumulation leading to ERK1/2 activation-mediated STAT1 phosphorylation and subsequent inhibition of downstream transcriptional target genes, including VCAM-1, TNF-α, IL-1β, and MCP-1. Interestingly, LPS-induced ERK1/2/STAT1 activation leads to the HMGB1 release from the nucleus into the extracellular space, where it binds to RAGE, while 3'-SL suppressed EC hyperpermeability by suppressing the HMGB1/RAGE axis. This interaction also led to VE-cadherin endothelial junction disassembly and endothelial cell monolayer disruption through ERK1/2/STAT1 modulation. In mouse endothelium, en face staining revealed that 3'-SL abolished LPS-stimulated ROS production and VCAM-1 overexpression.

SIGNIFICANCE

Our findings suggest that 3'-SL inhibits LPS-induced endothelial hyperpermeability by suppressing superoxide-mediated ERK1/2/STAT1 activation and HMGB1/RAGE axis. Therefore, 3'-SL may be a potential therapeutic agent for preventing the progression of atherosclerosis.

Human milk oligosaccharides 3'-sialyllactose and 6'-sialyllactose attenuate LPS-induced lung injury by inhibiting STAT1 and NF-κB signaling pathways

Acute lung injury (ALI) is the leading cause of respiratory diseases induced by uncontrolled inflammation and cell death. Lipopolysaccharide (LPS) is a major trigger of ALI in the progression through macrophage differentiation and the accelerated release of pro-inflammatory cytokines. The present study aimed to investigate the protective effects of human milk oligosaccharides, specifically 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL), on LPS-induced ALI and elucidate their underlying signaling pathways. The inhibitory effects of 3'-SL and 6'-SL on inflammation were evaluated using LPS-treated RAW 264.7 macrophages. To establish the ALI model, mice were treated with 10 mg/kg LPS for 24 h. Histological changes in the lung tissues were assessed using hematoxylin and eosin staining and immunofluorescence. LPS causes thickening of the alveolar wall infiltration of immune cells in lung tissues and increased serum levels of TNF-α, IL-1β, and GM-CSF. However, these effects were significantly alleviated by 100 mg/kg of 3'-SL and 6'-SL. Consistent with the inhibitory effects of 3'-SL and 6'-SL on LPS-induced pro-inflammatory cytokine secretion in serum, 3'-SL and 6'-SL suppressed mRNA expression of TNF-α, IL-1β, MCP-1, iNOS, and COX2 in LPS-induced RAW 264.7 cells. Mechanistically, 3'-SL and 6'-SL abolished LPS-mediated phosphorylation of NF-κB and STAT1. Interestingly, fludarabine treatment, a STAT1 inhibitor, did not affect LPS-mediated NF-κB phosphorylation. In summary, 3'-SL and 6'-SL protect LPS-induced macrophage activation and ALI through the STAT1 and NF-κB signaling pathways.