Xin Cong

Although salivary glands are highly vascularized, the microvascular endothelial barrier has only recently emerged as a pivotal determinant of glandular homeostasis and disease. This review synthesizes current understanding of the salivary gland endothelial barrier, with particular emphasis on the regulation of tight junctions (TJs). Structurally, the barrier comprises endothelial cells interconnected by TJs and adherens junctions, supported by a basement membrane and pericytes. Among TJ components, claudin-5 serves as a key endothelial-specific regulator of paracellular permeability, and is dynamically modulated by biochemical and mechanical stimuli during saliva secretion. Cholinergic, adrenergic, and neuropeptide signaling pathways coordinate to fine-tune endothelial permeability to meet the fluctuating secretory demands. Conversely, under pathological conditions, such as Sjögren’s syndrome, radiation-induced injury, diabetes mellitus, fibrotic diseases, and salivary gland tumors, the integrity of the endothelial TJ complex is impaired. These pathologies are characterized by aberrant TJ expression, mislocalization, and signaling-mediated junctional disassembly, which trigger vascular leakage and immune cell infiltration—two key processes that act as primary drivers of glandular dysfunction. Collectively, these findings enrich our understanding of the microvascular mechanisms that link endothelial barrier function to salivation, and highlight that the restoration of junctional integrity is a promising therapeutic strategy for salivary gland diseases.

The gingival epithelial barrier serves as a critical frontline defense in oral immunity and homeostasis. An intact epithelial barrier effectively prevents the penetration of harmful substances from the oral environment, whereas its disruption is closely associated with the pathogenesis of conditions such as periodontitis and oral lichen planus. Here, we established a topical application-based method to assess the integrity of the gingival epithelial barrier in mice. First, a mixture of fluorescently labeled dextrans with different molecular weights (40 or 70 kDa) in a 2% sodium carboxymethylcellulose was applied topically to the labial gingival surface of the molar region. After a 30 min incubation period, the maxilla was dissected and fixed in a customized holder for immediate imaging using a single-photon microscopy system. This approach enables visualization and quantification of tracers of different sizes across the epithelial layers, providing a functional readout of gingival epithelial barrier integrity applicable to studies of oral inflammation, wound healing, and disease modeling.

The gingival epithelial barrier serves as a critical frontline defense in oral immunity and homeostasis. An intact epithelial barrier effectively prevents the penetration of harmful substances from the oral environment, whereas its disruption is closely associated with the pathogenesis of conditions such as periodontitis and oral lichen planus. Here, we established a topical application-based method to assess the integrity of the gingival epithelial barrier in mice. First, a mixture of fluorescently labeled dextrans with different molecular weights (40 or 70 kDa) in a 2% sodium carboxymethylcellulose was applied topically to the labial gingival surface of the molar region. After a 30 min incubation period, the maxilla was dissected and fixed in a customized holder for immediate imaging using a single-photon microscopy system. This approach enables visualization and quantification of tracers of different sizes across the epithelial layers, providing a functional readout of gingival epithelial barrier integrity applicable to studies of oral inflammation, wound healing, and disease modeling.

Objective: To characterize the systemic effects of high-fat diet (HFD)-induced obesity across different ages, explore the microbiota-related obesity endotype using 16S rRNA sequencing, and identify key microbial genera as candidate markers for longitudinal monitoring and future interventional validation. Materials and methods: Male C57BL/6J mice were randomly assigned to a standard chow diet (SCD) or HFD group, maintained until 4, 12 and 18 months of age as the young, middle-aged and old groups, respectively, at which time animals were euthanized. Systemic effects were evaluated by measuring body weight, Lee’s index, glucose-lipid metabolism, liver function, and blood oxygen levels, coupled with behavioral tests for mood and cognitive performance. Blood samples were collected to quantify LPS and Aβ1–42 levels using ELISA. Oral and fecal samples were collected for 16S rRNA sequencing to analyze microbiota diversity and community structure. Differential genera were identified by LEfSe, and those consistently altered in both oral and gut samples were operationally designated as marker genera. Targeted metabolomics was performed to analyze short-chain fatty acids (SCFAs). Correlations were evaluated using Spearman analysis. Results: Compared with SCD, HFD mice showed systemic alterations across all age groups, including progressive obesity, elevated blood lipids and liver enzymes, accompanied by reduced blood oxygen, increased Aβ1–42 and LPS levels, increased anxiety-/depression-like behaviors, and impaired spatial memory. HFD significantly remodeled the alpha/beta-diversity and community structure of oral and gut microbiota, inducing stable enrichment of Romboutsia_B and depletion of beneficial genera ( Bifidobacterium , Akkermansia , and Muribaculum ). The abundance of Romboutsia_B positively correlated with obesity, blood lipids, liver enzyme levels, hypoxia, and inflammatory markers, but negatively correlated with multiple cognitive-behavioral parameters. Functional prediction and SCFA further profiling indicated that HFD enhanced lipid metabolism and environmental adaptation pathways, while reducing polysaccharide degradation and vitamin metabolism. Conclusions: Long-term HFD is associated with systemic remodeling of the oral-gut-liver-brain axis across ages. Romboutsia_B , a pro-inflammatory–associated genus stably enriched in the oral and gut across all age groups, holds potential as a noninvasive microbial biomarker and candidate target for future intervention studies for obesity and its liver-brain comorbidities.

Background and Objectives: Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening vascular disease with limited effective diagnostic and therapeutic strategies. Although endothelial barrier dysfunction represents an early event in TAAD pathogenesis, the role of endothelial tight junction proteins remains largely undefined. In this study, we systematically explored the function of claudin-5 (CLDN5), an endothelial-specific tight junction sealing protein, in TAAD through integrated bioinformatic, clinical, and experimental approaches. Materials and Methods: In the study, we combined bioinformatic analysis of the CLDN5 gene with clinical and cellular investigations. The clinical cohort included 44 patients with thoracic aortic dissection (TAAD) and 41 healthy controls. Plasma CLDN5 levels were measured by ELISA. Cellular studies involved treating human umbilical vein endothelial cells (HUVECs) with tumor necrosis factor-α (TNF-α) and performing CLDN5 knockdown, with barrier function assessed using transendothelial electrical resistance and permeability assays. Results: Plasma CLDN5 was significantly elevated in TAAD patients (14.20 ± 1.394 ng/mL) compared to controls (6.061 ± 0.8208 ng/mL, p < 0.05) and showed strong diagnostic potential with an area under the receiver operating characteristic curve (AUC) of 0.7877 (95% CI: 0.6897–0.8857). In cellular experiments, TNF-α treatment induced the release of CLDN5 fragments into the supernatant and reduced membrane CLDN5. Furthermore, CLDN5 knockdown directly impaired endothelial barrier function. Conclusions: Our findings identify CLDN5 as a promising circulating biomarker for TAAD diagnosis and provide new insights into TAAD pathogenesis, offering potential diagnostic strategies.

Aging is the predominant risk factor for several chronic disorders; therefore, elucidating the molecular and cellular mechanisms underlying age-related pathologies is essential for therapeutic advancement. Micheliolide (MCL), a naturally occurring guaianolide sesquiterpene lactone derived from Michelia champaca and Michelia compressa, has attracted increasing attention for its pharmacological potential. Its derivative, ACT001, enables the sustained release of MCL into the plasma in vivo, thereby enhancing oral bioavailability and improving therapeutic efficacy. ACT001 has recently received orphan drug designation for glioblastoma treatment, highlighting its clinical feasibility and safety profile. Increasing evidence indicates that MCL regulates age-related diseases by modulating inflammation, cell cycle, mitochondrial dysfunction, oxidative stress, and autophagy. By targeting key signaling pathways, including NF-κB, STAT3, NRF2, AMPK, and NLRP3, MCL/ACT001 demonstrated its protective effect against age-related diseases. This paper summarizes the current mechanistic insight and disease-specific evidence regarding MCL/ACT001 and further evaluates their therapeutic repositioning potential for age-related diseases, including cardiovascular and cerebrovascular diseases, fibrotic conditions, immune disorders, metabolic diseases, and tumors. Additionally, we discussed key translational challenges.

Tricellulin, a key tricellular tight junction (TJ) protein, is essential for maintaining the barrier integrity of acinar epithelia against macromolecular passage in salivary glands. This study aims to explore the role and regulatory mechanism of tricellulin in the development of salivary gland hypofunction in Sjögren’s syndrome (SS). Employing a multifaceted approach involving patient biopsies, non-obese diabetic (NOD) mice as a SS model, salivary gland acinar cell-specific tricellulin conditional knockout (Tric ^CKO ) mice, and IFN-γ-stimulated salivary gland epithelial cells, we investigated the role of tricellulin in SS-related hyposalivation. Our data revealed diminished levels of tricellulin in salivary glands of SS patients. Similarly, NOD mice displayed a reduction in tricellulin expression from the onset of the disease, concomitant with hyposecretion and an increase in salivary albumin content. Consistent with these findings, Tric ^CKO mice exhibited both hyposecretion and leakage of macromolecular tracers when compared to control animals. Mechanistically, the JAK/STAT1/miR-145 axis was identified as mediating the IFN-γ-induced downregulation of tricellulin. Treatment with AT1001, a TJ sealer, ameliorated epithelial barrier dysfunction, restored tricellulin expression, and consequently alleviated hyposalivation in NOD mice. Importantly, treatment with miR-145 antagomir to specifically recover the expression of tricellulin in NOD mice significantly alleviated hyposalivation and macromolecular leakage. Collectively, we identified that tricellulin deficiency in salivary glands contributed to hyposalivation in SS. Our findings highlight tricellulin as a potential therapeutic target for hyposecretion, particularly in the context of reinforcing epithelial barrier function through preventing leakage of macromolecules in salivary glands.

Objective: Aortic dissection (AD) is a severe aortic disease with high mortality, and its pathogenesis remains elusive. To explore the regulatory mechanisms of AD, we integrated public RNA sequencing (RNA-seq) and single-cell RNA sequencing (scRNA-seq) datasets to screen the hub genes of AD and further analyzed their functions, which may provide references to the diagnosis and treatment of AD.Methods: Four AD-related datasets were obtained from the Gene Expression Omnibus (GEO) database. Weighted gene co-expression network analysis and differential expression analysis were applied to identify overlapping genes in dataset GSE153434. Protein–protein interaction (PPI) network was constructed based on overlapping genes. Five methods (closeness, degree, EPC, MCC, and MNN) were used to pick hub genes. The receiver operating characteristic curve was used to evaluate the diagnostic efficiency of the hub genes in extra datasets GSE98770 and GSE52093. scRNA-seq dataset GSE213740 was used to explore the expression and function of the hub genes at the single-cell level. Quantitative real-time polymerase chain reaction was used to verify the expression of hub genes in beta-aminopropionitrile (BAPN)-induced mouse thoracic aortic aneurysm and dissection (TAAD) model.Results: A total of 71 overlapping genes were screened by intersecting the significant genes in the pink module and the differentially expressed genes. A PPI network with 45 nodes and 74 edges was generated, and five top hub genes (HIF1A, HGF, HMOX1, ITGA5, and ITGB3) were identified. All the hub genes had area under the curve values above 0.55. scRNA-seq data analysis showed that HIF1A was significantly upregulated in macrophages and HGF was significantly upregulated in vascular smooth muscle cells (SMCs) of the ascending aortas in AD patients. HIF1A may transcriptionally regulate multiple downstream target genes involving inflammation (TLR2, ALOX5AP, and MIF), glycolysis (ENO1, LDHA, and GAPDH), tissue remodeling (PLAU), and angiogenesis (SERPIN and VEGFA). HGF may participate in the signaling among SMCs, fibroblasts, and endothelial cells through binding to different receptors (MET, EGFR, IGF1R, and KDR). The mRNA expression of Hif1a, Hgf, and their target genes, including Alox5ap, Serpine1, Tlr2, Plau, Egfr, and Igf1r, was significantly upregulated in aortic tissues of BAPN-treated mice.Conclusion: By integrating RNA-seq and scRNA-seq data, we identified HIF1A and HGF as two hub genes with good diagnostic efficiency for AD. HIF1A in macrophages may promote AD formation by promoting inflammation, glycolysis, tissue remodeling, and angiogenesis, and HGF may mediate signaling among SMCs, fibroblasts, and endothelial cells in the development of AD.

With increased awareness of dry eye disease (DED), a multitude of therapeutic options have become available. Nevertheless, the treatment of severe DED remains difficult. In a patient whose DED is related to the loss of lacrimal function without severe destruction of the salivary glands, autologous transplantation of the latter as functioning exocrine tissue to rebuild a stable tear film is an attractive idea. All three major and minor salivary glands have been used for such transplantation. Due to the complications associated with and unfavorable prognosis of parotid duct and sublingual gland transplantation, surgeons now prefer to use the submandibular gland (SMG) for such procedures. The transplantation of the SMG not only has a high survival rate, but also improves dry eye symptoms and signs for more than 20 years post-surgery. The regulation of the secretion of the transplanted SMG is critical because the denervated SMG changes its mechanism of secretion. Innovative procedures have been developed to stimulate secretion in order to prevent the obstruction of the Wharton’s duct and to decrease secretion when postoperative “epiphora” occurs. Among the minor salivary glands, the transplantation of the labial salivary glands is the most successful in the long-term. The measurement of the flow rates of minor salivary glands and donor-site selection are critical steps before surgery.