Expression Of Claudin-1 Research Articles

Absence of claudin-3 does not alter intestinal absorption of phosphate in mice

Intestinal absorption of phosphate is bimodal, consisting of a transcellular pathway and a poorly characterized paracellular mode, even though the latter one contributes to the bulk of absorption under normal dietary conditions. Claudin-3 (Cldn3), a tight junction protein present along the whole intestine in mice, has been proposed to tighten the paracellular pathway for phosphate. The aim of this work was to characterize the phosphate-related phenotype of Cldn3-deficient mice. Cldn3-deficient mice and wildtype littermates were fed standard diet or challenged for 3 days with high dietary phosphate. Feces, urine, blood, intestinal segments and kidneys were collected. Measurements included fecal, urinary, and plasma concentrations of phosphate and calcium, plasma levels of phosphate-regulating hormones, evaluation of trans- and paracellular phosphate transport across jejunum and ileum, and analysis of intestinal phosphate and calcium permeabilities. Fecal and urinary excretion of phosphate as well as its plasma concentration was similar in both genotypes, under standard and high-phosphate diet. However, Cldn3-deficient mice challenged with high dietary phosphate had a reduced urinary calcium excretion and increased plasma levels of calcitriol. Intact FGF23 concentration was also similar in both groups, regardless of the dietary conditions. We found no differences either in intestinal phosphate transport (trans- or paracellular) and phosphate and calcium permeabilities between genotypes. The intestinal expression of claudin-7 remained unaltered in Cldn3-deficient mice. Our data do not provide evidence for a decisive role of Cldn3 for intestinal phosphate absorption and phosphate homeostasis. In addition, our data suggest a novel role of Cldn3 in regulating calcitriol levels.

Effects of taurine on the growth performance, diarrhea, oxidative stress and intestinal barrier function of weanling piglets.

Oxidative damage resulting from weaning stress significantly impacts the growth performance and health status of piglets. Taurine, a dietary antioxidant with diverse functions, was investigated in this study for its protective role against weaning stress-induced oxidative damage and its underlying mechanism. Forty 28-day-old male castrated weaned piglets were randomly assigned to four groups. The control group received the basal diet, while the experimental groups were fed the basal diet supplemented with 0.1, 0.2%, or 0.3% taurine over a 28-day period. In vitro, H2O2 was utilized to induce oxidative damage to the jejunal mucosa of piglets via IPEC-J2 cells. The results demonstrated that taurine supplementation reduced the incidence of diarrhea in piglets compared to that in the control group (p < 0.05); the addition of 0.2 and 0.3% taurine led to increased average daily gain and improved feed conversion efficiency in weaned piglets, showing a linear dose-response correlation (p < 0.05). Taurine supplementation at 0.2 and 0.3% enhanced the activities of serum CAT and GSH-Px while decreasing the levels of serum NO, XOD, GSSG, and MDA (p < 0.05). Moreover, it significantly elevated the levels of GSS, Trx, POD, complex I, mt-nd5, and mt-nd6, enhancing superoxide anion scavenging capacity and the hydroxyl-free scavenging rate in the livers of weaned piglets while reducing NO levels in the liver (p < 0.05). Additionally, 0.2 and 0.3% taurine supplementation decreased serum IL-6 levels and elevated the concentrations of IgA, IgG, and IL-10 in weaned piglets (p < 0.05). The levels of occludin, claudin, and ZO-1 in the jejunum mucosa of weaned piglets increased with 0.2 and 0.3% taurine supplementation (p < 0.05). In IPEC-J2 cells, pretreatment with 25 mM taurine for 24 h enhanced the activities of SOD and CAT; reduced the MDA content; upregulated the mRNA expression of various genes, including ZO-1, occludin, claudin-1, Nrf2, and HO-1; and reversed the oxidative damage induced by H2O2 exposure (p < 0.05). Overall, the findings suggest that the inclusion of 2 and 3% taurine in the diet can enhance growth performance, reduce diarrhea rates, ameliorate oxidative stress and inflammation, and promote intestinal barrier function in weaned piglets.

Formation mechanism, prevention of malignant ascites effusion and reduction of intestinal mucosal irritation of natural microemulsion from Euphorbia lathyris Pulveratum

Malignant ascites effusion (MAE) is a common complication of advanced malignant tumors with limited treatments. Euphorbia lathyris (EL) has a long history of application in patients with edema and ascites. Herein, we reported for the first time a mode in which EL and EL Pulveratum (PEL) spontaneously formed natural microemulsions (ELM and PELM) without the addition of any carriers and excipients, and found that the protein and phospholipid contained in them encapsulated fatty oil and diterpenoid esters through non-covalent interactions. The denaturation and degradation of protein in PELM resulted in stronger binding of diterpenoid esters to the hydrophobic region of protein, which facilitated the sustained and slow release of diterpenoid esters and improved their bioavailability in vivo, thereby retaining the efficacy of preventing MAE while alleviating the irritation of intestinal mucosa. The mechanism by which PELM retained efficacy might be related to increased feces moisture and urine volume, and decreased expression of AVPR2, cAMP, PKA and AQP3 in MAE mice. And its mechanism of reducing intestinal mucosal irritation was related to decreased cell apoptosis, amelioration of oxidative stress, elevation of mitochondrial membrane potential, and up-regulation of Occludin and Claudin-1 expression in IEC-6 cells. This nano-adjuvant-free natural microemulsions may be a promising therapeutic strategy in the field of phytochemistry for promoting the application of natural and efficient nano-aggregates spontaneously formed by medicinal plants in MAE, and provide a new perspective for advancing the development of the fusion of Chinese herbal medicine and nanomedicine and its clinical translation.

Compound probiotics and glycyrrhizic acid alleviate DON-induced liver damage linked to the alteration of lipid metabolism in piglets

Compound probiotics are capable of effectively breaking down mycotoxins, and glycyrrhizic acid (GA) exhibits hepatoprotective properties. However, the protective efficacy and the underlying mechanism of combined intervention of GA and probiotics (GAP) on ameliorating Deoxynivalenol (DON)-induced liver toxicity remains unclear. This experiment involved 120 weaned piglets, encompassing the control group, the DON group, and the GPD group (E. faecalis and S. cerevisiae + GA + DON). Results showed that GAP significantly mitigated DON-related liver damage and oxidative stress. Furthermore, GAP inhibited the Nrf2/MAPK/NF-κB pathway, ultimately decreasing liver inflammation and apoptosis. Additionally, GAP significantly enhanced the expressions of ZO-1, GLUT2, PePT1, ASCT2, Occludin and Claudin-1. Moreover, metabolomics analysis revealed that GAP modulated lipid metabolism and mitigated liver damage by elevating serum levels of metabolites, such as phosphatidylcholine, phosphatidylethanolamine, and 3-amino-4-hydroxybenzoic acid. The research provides a theoretically based framework for using GAP to combat DON-induced hepatotoxicity in piglets.

The protective effect of dulcitol on lipopolysaccharide-induced intestinal injury in piglets: mechanistic insights

This study investigated the protective effect of dulcitol on LPS-induced intestinal injury in piglets and explored the underlying molecular mechanisms. A total of 108 piglets were divided into three groups: CON, LPS, and DUL. The CON and LPS groups were fed a basal diet, the DUL group was fed a diet supplementation with 500 mg/kg dulcitol. On day 29, 6 piglets in the LPS and DUL groups were injected with 100 μg/kg BW of LPS. At 4 h postchallenge, all pigs were slaughtered, and colonic samples were collected. Results showed that dulcitol supplementation boosted intestinal barrier function in LPS-challenged piglets by enhancing intestinal morphology and integrity, and increasing the gene expression of zonula occludens-1, claudin-1, and occludin in the colonic mucosa (P <0.05). Metabolomics showed DUL supplementation mainly increased (P <0.05) the metabolites related to steroid and vitamin metabolism (Cholesterol and Vitamin C). Proteomics showed that dulcitol supplementation altered the protein expression involved in maintaining barrier integrity (FN1, CADM1, and PARD3), inhibiting inflammatory response (SLP1, SFN, and IRF3), and apoptosis (including FAS, ING1, BTK, MTHFR, NOX, and P53BP2) in LPS-challenged piglets (P <0.05). Additionally, dulcitol addition also suppressed the TLR4/NF-κB signaling pathway and apoptosis in mRNA and protein levels. Dulcitol increased the abundance of short-chain fatty acid-producing bacteria (Lactobacillus, Blautia, and Faecalibacterium) at the genus level, but decreased the relative abundance of Proteobacteria at the phylum level and Pseudomonas and Delftia at the genus level in piglets (P<.05). In conclusion, these results suggested that the addition of dulcitol alleviated LPS-induced intestinal barrier injury in piglets, probably by maintaining its integrity, inhibiting the TLR4/NF-κB signaling pathways and apoptosis, and modulating the gut microbiota. Therefore, dulcitol can be considered a potential dietary additive for improving intestinal health in pig models.

Claudin and transmembrane receptor protein gene expressions are reversely correlated in peritumoral brain edema.

Peritumoral brain edema (PTBE) has been widely reported with many brain tumors, especially with glioma. Since the blood-brain barrier (BBB) is essential for maintaining minimal permeability, any alteration in the interaction of BBB components, specifically in astrocytes and tight junctions (TJ), can result in disrupting the homeostasis of the BBB and making it severely leaky, which subsequently generates edema. This study aimed to evaluate the functional gliovascular unit of the BBB by examining changes in the expression of claudin (CLDN) genes and the expression of transient receptor potential (TRP) membrane channels, additionally to define the correlation between their expressions. The evaluation was conducted using invitro spheroid swelling models and tumor samples from glioma patients with PTBE. The results of the spheroid model showed that the genes TRPC3, TRPC4, TRPC5, and TRPV1 were upregulated in glioma cells either wild-type isocitrate dehydrogenase 1 (IDH1) or the IDH1 R132H mutant, with or without NaCl treatment. Furthermore, TRP genes appeared to adversely correlate with the up regulation of CLDN1, CLDN3, and CLDN5 genes. Besides, the upregulation of TRPC1 and TRPC4 in IDH1mt-R132H glioma cells. On the other hand, the correlation analysis revealed different correlations between different proteins in PTBE. CLDN1 exhibits a slight positive correlation with CLDN3. Similarly, TRPV1 displays a slight positive correlation with TRPC1. In contrast, TRPC4 shows a slight negative correlation with TRPC5. On the other hand, TRPC3 demonstrates a slight positive correlation with TRPC5, while the non-PTBE analysis highlights a moderate positive correlation between CLDN1 and TRPM4 while CLDN3 exhibits a moderate negative correlation with TRPC4. Additionally, CLDN5 demonstrates a slight negative correlation with TRPC4 but a moderate positive correlation with TRPC3. Furthermore, TRPC1 have a slight negative correlation with TRPV1, TRPC3 exhibiting a slight positive correlation with TRPC4, and TRPV1 showing a slight negative correlation with TRPC5. As a conclusion, the current study provided evidence of a slight negative correlation between TRPs and CLDN gene expression in PTBE patients and confirmatory results with some of the genes in cell model of edema.

Claudin-4 expression in placentas from a murine model infected with Salmonella enterica

Claudin-4 expression in placentas from a murine model infected with Salmonella enterica

Hyperuricemia drives intestinal barrier dysfunction by regulating gut microbiota

BackgroundHyperuricemia elevates gut permeability; however, the risk of its influence on the compromised intestinal barrier is poorly understood. AimsThis study was carried out, aiming to elucidate the orchestrators and disruptors of intestinal barrier in hyperuricemia. MethodsA mouse model of hyperuricemia was induced by administering adenine and oteracil potassium to mice. Allopurinol was used to decrease uric acid level, and antibiotics were administered to mice to deplete gut microbiota. Intestinal permeability was assessed using FITC-labeled dextran. Changes in gut microbial community were analyzed through 16S rRNA sequencing. IL-1β and TNF-α levels were quantified using ELISA. The expression of tight junction protein genes, TLR4, p65 and IL-1β, was determined with Q-PCR and Western blotting. ResultsAllopurinol treatment effectively reduced intestinal permeability and serum TNF-α levels. Antibiotic treatment alleviated but not abolished intestinal permeability. Uric acid alone was insufficient to increase Coca2 monolayer permeability. Allopurinol treatment altered microbial composition and suppressed opportunistic infections. Re-establishing hyperuricemia in a germfree mouse model protected mice from intestinal injury. Allopurinol and antibiotic treatments reduced TLR4 and IL-1β expressions, increased occludin and claudin-1 expressions but suppressed NF-ĸB p65 signaling. However, removing gut microbiota aggravated lipid metabolic dysfunction. ConclusionGut microbiota is a direct and specific cause for intestinal barrier dysfunction.

Significance and Possible Biological Mechanism for CLDN8 Downregulation in Kidney Renal Clear Cell Carcinoma Tissues.

The clinical role of claudin 8 (CLDN8) in kidney renal clear cell carcinoma (KIRC) remains unclarified. Herein, the expression level and potential molecular mechanisms of CLDN8 underlying KIRC were determined. High-throughput datasets of KIRC were collected from GEO, ArrayExpress, SRA, and TCGA databases to determine the mRNA expression level of the CLDN8. In-house tissue microarrays and immunochemistry were performed to examine CLDN8 protein expression. A summary receiver operating characteristic curve (SROC) and standardized mean difference (SMD) forest plot were generated using Stata v16.0. Single-cell analysis was conducted to further prove the expression level of CLDN8. A clustered regularly interspaced short palindromic repeats knockout screen analysis was executed to assess the growth impact of CLDN8. Functional enrichment analysis was conducted using the Metascape database. Additionally, single-sample gene set enrichment analysis was implied to explore immune cell infiltration in KIRC. A total of 17 mRNA datasets comprising 1,060 KIRC samples and 452 non-cancerous control samples were included in this study. Additionally, 105 KIRC and 16 non-KIRC tissues were analyzed using in-house immunohistochemistry. The combined SMD was -5.25 (95% confidence interval (CI): -6.13 to -4.37), and CLDN8 downregulation yielded an SROC area under the curve (AUC) close to 1.00 (95% CI: 0.99 - 1.00). CLDN8 downregulation was also confirmed at the single-cell level. Knocking out CLDN8 stimulated KIRC cell proliferation. Lower CLDN8 expression was correlated with worse overall survival of KIRC patients (hazard ratio of CLDN8 downregulation = 1.69, 95% CI: 1.2 - 2.4). Functional pathways associated with CLDN8 co-expressed genes were centered on carbon metabolism obstruction, with key hub genes ACADM, ACO2, NDUFS1, PDHB, SDHD, SUCLA2, SUCLG1, and SUCLG2. CLDN8 is downregulated in KIRC and is considered a potential tumor suppressor. CLDN8 deficiency may promote the initiation and progression of KIRC, potentially in conjunction with metabolic dysfunction.

Association between Vitamin D Receptor Polymorphisms, Tight Junction Proteins and Clinical Features of Adult Patients with Atopic Dermatitis.

Few studies have explored the intricate connections between vitamin D receptor (VDR) gene polymorphisms, VDR, tight junction (TJ) protein expression and clinical features of atopic dermatitis (AD). From 43 adult AD patients, VDR polymorphisms were genotyped from peripheral blood samples using polymerase chain reaction-restriction fragment length polymorphism. VDR, occludin, claudin-1 and ZO-1 protein expression from skin lesion biopsies were assessed by immunohistochemistry. The A1012G heterozygous VDR polymorphism exhibited a lower odds ratio (OR) for juvenile AD onset (OR: 0.046, 95% CI 0.004-0.51, p=0.012). In contrast, the presence of ≥2 homozygous VDR polymorphisms were significantly associated with positive skin prick test (SPT) (10/20, 50%) vs. negative SPT (1/23, 4.3%; p=0.0003). The most highly expressed TJ proteins in lesions of AD patients were claudin-1 and zonulin-1 (ZO-1), while VDR and occludin were less prevalent. A significant correlation was observed between ZO-1 expression and a body mass index ≥30 kg/m2 (OR: 12.1, 95% CI 1.06-137.9, p=0.045). Claudin-1 expression was associated with a positive SPT (OR: 8.23, 95% CI 1.04-65.5, p=0.046) and serum 25(OH)D levels were negatively correlated with ZO-1 expression (rho= -0.43, p=0.0058). This study provides novel insights into the relationship between VDR gene polymorphisms, VDR, TJ protein expression, and clinical features in adult AD patients, highlighting a significant role of vitamin D in the pathophysiology of this disease.

Polysaccharides, the active component of Dendrobiumofficinale flower, ameliorates chronic pharyngitis in rats via TLR4/NF-κb pathway regulation

Ethnopharmacological relevanceChronic pharyngitis persistently afflicts a large population and accounts for approximately one-third of otolaryngology patients. Currently, the treatment of CP remains controversial because of the poor outcomes. Dendrobium officinale is a well-used “Yin-nourishing” traditional Chinese medicinal and edible herb used for thousands of years in China. The flowers of D. officinale are often used in folk of China to make tea for voice protection on and throat clearing. Aim of the studyThis study was to evaluate beneficial effects of polysaccharides from D. officinale flower (DOFP) on CP and its potential mechanisms. MethodsChemical characterization of DOFP, including polysaccharide content and monosaccharide composition, structural characterization using Fourier transform infrared spectroscopy were performed. A CP model was established in rats by administering a mixture of Chinese Baijiu and chili pepper liquid, combined with low-concentration ammonia spraying. The general states, amount of oral secretion, and apparent state of the pharynx of CP rats were observed during the period of DOFP administration. Furthermore, hemorheological parameters were measured using an automatic hematology analyzer. The levels of tumor necrosis factor-α (TNF-α), interleukin 1β (1L-1β), lipopolysaccharide (LPS), and D-lactate (D-LA) in the serum were measured by enzyme-linked immunosorbent assay. Morphological changes in the pharynx and colon were observed by hematoxylin-eosin staining. The expression of nuclear factor-κB p65 (NF-κB p65), p-NF-κB p65, cyclooxygenase-2 (COX-2), interleukin 1β（IL-1β）and mucin 5AC (MUC5AC) in the pharynx,Claudin-1, Occludin, and interleukin 6 (IL-6) in the colon was detected by immunohistochemistry and Western Blot. The mRNA expression of TLR4, COX-2, and IL-1β in the pharynx were determined using reverse transcription quantitative real-time PCR. ResultsIn this study, DOFP with a total polysaccharide content of 71.44% and a composition of D-mannose, galacturonic acid, glucose, galactose, and arabinose in a molar ratio of 3.95:2.19:1.00:0.74:1.30, was isolated from the flowers of D. officinale. DOFP improved the general state and exhibited significant effects on reducing oral secretion, alleviating pharyngeal injury, suppressing inflammatory cell infiltration in the pharynx, decreasing the serum levels of TNF-α and IL-1β, and reducing the number of white blood cells and lymphocytes in the model rats. Moreover, the expressions of TLR4, p-NF-κB p65, COX-2, IL-1β and MUC5AC in the pharynx of model rats were obviously inhibited. In addition, the levels of LPS, D-LA in the serum and the protein expression of IL-6 in the colon were downregulated when the protein expression of Occludin and Claudin-1 in the colon were upregulated. ConclusionsDOFP exerts significant ameliorating effects on CP and it likely acts by inhibiting LPS/TLR4-associated inflammatory mediator activation and reducing excessive secretion of mucus by repairing the intestinal barrier in CP rats.

Research Note: Poria cocos polysaccharide alleviates lipopolysaccharide-induced intestinal inflammation and barrier damage in broiler chickens

This study aimed to explore the impact of dietary supplementation of Poria cocos polysaccharide (PCP) on the lipopolysaccharide(LPS)-induced intestinal inflammation, morphology, and barrier damage in broilers. A total of 240 1-day-old male Arbor Acre broilers were randomly divided into 4 groups in a 2 × 2 factorial design comprising PCP supplementation (0 or 2 g/kg PCP from d 1 to 23) and LPS challenge (intraperitoneal injection of 1.5 mg/kg body weight of LPS or the same volume of sterile saline at d 22). Our results showed that compared to the non-LPS-treated groups, the treated birds showed a decrease in the ADG, VH, V/C, and the expression of ZO-1, occludin, claudin 1, and mucin2 in the duodenum and jejunum (P < 0.05). However, dietary PCP supplementation significantly mitigated these effects (P < 0.05) except for mucin2 in the duodenum. Furthermore, LPS treatment increased the levels of sIgA and upregulated the mRNA abundances of IL-1β, IL-6, TNF-α, IFN-γ, TLR-4, and MyD88 both in the duodenal and jejunal mucosa (P < 0.05). Whereas, PCP supplementation significantly reversed the LPS-induced effects on these genes (P < 0.05) except for the TLR-4 and MyD88. However, LPS did not impact the expression of anti-inflammatory IL-10 in the duodenal and jejunal mucosa (P > 0.05). Briefly, this study implied that dietary PCP supplementation could ameliorate intestinal inflammation and mucosal damage of LPS-challenged broilers, improving broiler performance.

Protection of Tight Junctional Complexes between hCMEC/D3 Cells by Deep-Sea Fibrinolytic Compound FGFC1.

Tight junctional complexes (TJCs) between cerebral microvascular endothelial cells (CMECs) are essential parts of the blood-brain barrier (BBB), whose regulation closely correlates to the BBB's integrity and function. hCMEC/D3 is the typical cell line used to imitate and investigate the barrier function of the BBB via the construction of an in vitro model. This study aims to investigate the protective effect of the deep-sea-derived fibrinolytic compound FGFC1 against H2O2-induced dysfunction of TJCs and to elucidate the underlying mechanism. The barrier function was shown to decline following exposure to 1 mM H2O2 in an in vitro model of hCMEC/D3 cells, with a decreasing temperature-corrected transendothelial electrical resistance (tcTEER) value. The decrease in the tcTEER value was significantly inhibited by 80 or 100 µM FGFC1, which suggested it efficiently protected the barrier integrity, allowing it to maintain its function against the H2O2-induced dysfunction. According to immunofluorescence microscopy (IFM) and quantitative real-time polymerase chain reaction (qRT-PCR), compared to the H2O2-treated group, 80~100 µM FGFC1 enhanced the expression of claudin-5 (CLDN-5) and VE-cadherin (VE-cad). And this enhancement was indicated to be mainly achieved by both up-regulation of CLDN-5 and inhibition of the down-regulation by H2O2 of VE-cad at the transcriptional level. Supported by FGFC1's molecular docking to these proteins with reasonable binding energy, FGFC1 was proved to exert a positive effect on TJCs' barrier function in hCMEC/D3 cells via targeting CLDN-5 and VE-cad. This is the first report on the protection against H2O2-induced barrier dysfunction by FGFC1 in addition to its thrombolytic effect. With CLDN-5 and VE-cad as the potential target proteins of FGFC1, this study provides evidence at the cellular and molecular levels for FGFC1's reducing the risk of bleeding transformation following its application in thrombolytic therapy for cerebral thrombosis.

The Clinicopathological and Molecular Characteristics of Endocervical Gastric-Type Adenocarcinoma and the Use of Claudin18.2 as a Potential Therapeutic Target

Endocervical gastric-type adenocarcinoma (GAS) is an aggressive type of endocervical mucinous adenocarcinoma characterized as being unrelated to human papillomavirus (HPV) and resistant to chemo/radiotherapy. In this study, we investigated the histology, immunohistochemistry patterns, and molecular characteristics in a large cohort of GAS (n = 62). Histologically, the majority of GAS cases exhibited a distinct morphology resembling gastric glands, although 2 exceptional cases exhibited HPV-associated adenocarcinoma morphology while retaining the characteristic histology of GAS at the invasive front. By immunohistochemistry, Claudin18.2 emerged as a highly sensitive and specific marker for GAS. Additionally, the strong expression of Claudin18.2 in patients with GAS indicated the potential of anti-Claudin18.2 therapy in the treatment of GAS. Other immunohistochemistry markers, including Muc6, p16, p53, Pax8, ER, and PR, may provide additional diagnostic clues for GAS. Quantitative methylation analysis revealed that the overexpression of Claudin18.2 in GAS was governed by the hypomethylation of the CLDN18.2 promoter CpG islands. To further elucidate the pathogenic mechanisms of GAS and its relationship with gastric adenocarcinoma, we performed whole exome sequencing on 11 GAS and 9 gastric adenocarcinomas. TP53, CDKN2A, STK11, and TTN emerged as the most frequently mutated genes in GAS. Mutations in these genes primarily affected cell growth, cell cycle regulation, senescence, and apoptosis. Intriguingly, these top mutated genes in GAS were also commonly mutated in gastric and pancreaticobiliary adenocarcinomas. Regarding germline variants, we identified a probably pathogenic variant in SPINK1, a gene linked to hereditary pancreatic cancer syndrome, in one GAS sample. This finding suggests a potential pathogenic link between pancreatic cancers and GAS. Overall, GAS exhibits molecular characteristics that resemble those observed in gastric and pancreaticobiliary adenocarcinomas, thereby lending support to the aggressive nature of GAS compared with HPV-associated adenocarcinoma.

Enhancement of chemoresistance by claudin-1-mediated formation of amino acid barriers in human lung adenocarcinoma A549 cells

Claudin-1 (CLDN1) is highly expressed in human lung adenocarcinoma-derived A549 cells and is involved in the augmentation of chemoresistance. However, the mechanism of chemoresistance is not fully understood. In the tumor microenvironment, cancer cells are exposed to stress conditions such as hypoxia and malnutrition. Here, we investigated the effect of CLDN1 expression on amino acid (AA) flux and chemoresistance using A549 cells. The expression of L-type AA transporters, LAT1 and LAT3, was decreased by CLDN1 silencing in A549 spheroids. A reduction in extracellular AA concentration increased the expression of these AA transporters in two-dimensional (2D) cultured cells. The paracellular AA flux except for Ser, Thr, Tyr, Ala, and Gly was enhanced by CLDN1 silencing. These results suggest that CLDN1 forms a paracellular barrier to some AAs, leading to the elevation of LAT1/3 expression in spheroids. The production of reactive oxygen species in the mitochondria and cytosol was decreased by CLDN1 silencing in spheroids, resulting in downregulation of the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its target antioxidant genes. CLDN1 silencing enhanced the cytotoxicity of anticancer drugs including doxorubicin and cisplatin, which was blocked by sulforaphane, an inducer of Nrf2 signaling. Similarly, the anticancer-induced toxicity was enhanced by Nrf2 silencing. In 2D cultured cells, the anticancer-induced toxicity was attenuated by AA deficiency and sulforaphane. We suggest that CLDN1 forms an AA barrier in spheroids, leading to the augmentation of Nrf2-dependent chemoresistance in A549 cells.

Gymnemic acid alleviates gut barrier disruption and lipid dysmetabolism via regulating gut microbiota in HFD hamsters

Gut microbiota dysbiosis and gut barrier disruption are key events associated with high-fat diet (HFD)-induced systemic metabolic disorders. Gymnemic acid (GA) has been reported to have an important role in alleviating HFD-induced disorders of glycolipid metabolism, but its regulatory role in HFD-induced disorders of the gut microbiota and gut barrier function has not been elucidated. Here we showed that GA intervention in HFD-induced hamsters increased the relative abundance of short-chain fatty acid (SCFA)-producing microbes including Lactobacillus (P<.05) and Lachnoclostridium (P<.01) in the gut, and reduced the relative abundance of lipopolysaccharide (LPS)-producing microbes including Enterococcus (P<.05) and Bacteroides (P<.05), subsequently improving HFD-induced intestinal barrier dysfunction and systemic inflammation. Specifically, GA intervention reduced mRNA expression of inflammatory cytokines, including IL-1β, IL-6, and TNF-α (P<.01), increased mRNA expression of antioxidant-related genes, including Nfe2l2, Ho-1, and Nqo1 (P<.01), and increased mRNA expression of intestinal tight junction proteins, including Occludin and Claudin-1 (P<.01), thereby improving gut barrier function of HFD hamsters. This ameliorative effect of GA on the gut of HFD hamsters may further promote lipid metabolic balance in liver and adipose tissue by regulating the Toll-like receptor 4 (TLR4)-nuclear factor-κB (NF-κB) signaling pathway. Taken together, these results systematically revealed the important role of GA in regulating HFD-induced gut microbiota disturbance and gut barrier function impairment, providing a potential clinical theoretical basis for targeted treatment of HFD-induced microbiota dysbiosis.

Mailuo Shutong pills inhibit neuroinflammation by regulating glucose metabolism disorders to protect mice from cerebral ischemia-reperfusion injury

Ethnopharmacological relevanceMailuo Shutong Pill (MLST), a traditional Chinese medicine (TCM), has been widely used for clearing heat and detoxifying, eliminating stasis and dredging meridians, dispelling dampness and diminishing swelling. Earlier study found that MLST could improve cerebral ischemic-reperfusion injury, however, the potential mechanism has not been well evaluated. Aim of studyIn this study, a well established and widely used mice model of middle cerebral artery occlusion/reperfusion (MCAO/R) was preformed to evaluate the protective function of MLST on cerebral ischemic-reperfusion injury and further discuss the potential pharmacological mechanisms. Materials and methodsChemical profiling of MLST was analyzed based on Ultra-high-performance liquid chromatography electrospray ionization orbitrap tandem mass spectrometry. ICR mice were challenged by MCAO/R surgery. The protective effect of MLST on MCAO/R injury was evaluated by neurological deficit score, cerebral infarct rate, brain water content, H&E and nissl staining. The blood-brain barrier (BBB) integrity was detected by Evans blue staining. The potential pharmacological mechanism of MLST in treating MCAO/R injury was further elucidated by the methods of proteomics, central carbon targeted metabolomics, as well as Western blot. Immunohistochemistry was used to detect the microglia infiltration, enzyme linked immunosorbent assay (ELISA) kit was explored to evaluate the content of IL-1β, TNF-α and IL-6 in brain tissue, and Western blot was used to detect proteins expression in brain tissue. ResultsA total of 76 chemical compounds have been determined in MLST. MLST effectively protected mice from MCAO/R injury, which was confirmed by lower neurological deficit score, cerebral infarct rate, brain water content and nissl body loss, and improved brain pathology. Meanwhile, MLST upregulated the expression of ZO-1, Occludin and Claudin 5 by downregulating the ratio of TIMP1/MMP9 to suppress the entrance of Evans blue to brain tissue, indicating that MLST maintained the integrity of BBB. Further studies indicated that MLST inhibited the inflammatory level of brain tissue by inhibiting microglia infiltration and downregulating NLRP3 inflammasome signaling pathway. The results of proteomics, Western blot, and central carbon targeted metabolomics confirmed that MLST regulated Glycolysis/Gluconogenesis, Pyruvate metabolism and TCA cycle in brain tissue of mice with MCAO/R. ConclusionMLST inhibits neuroinflammation by regulating glucose metabolism disorders to interfere with immune metabolism reprogramming and inhibit the NLRP3 inflammasome signaling pathway, and finally improve cerebral ischemia-reperfusion injury. This study confirms that MLST is a potential drug for treating Cerebral ischemic stroke.

NMN Synbiotics: A Multifaceted Therapeutic Approach for Alzheimer's Disease.

With the aging global population, Alzheimer's disease (AD) has become a significant social and economic burden, necessitating the development of novel therapeutic strategies. This study investigates the therapeutic potential of nicotinamide mononucleotide (NMN) synbiotics, a combination of NMN, Lactiplantibacillus plantarum CGMCC 1.16089, and lactulose, in mitigating AD pathology. APP/PS1 mice were supplemented with NMN synbiotics and compared against control groups. The effects on amyloid-β (Aβ) deposition, intestinal histopathology, tight junction proteins, inflammatory cytokines, and reactive oxygen species (ROS) levels were assessed. NMN synbiotics intervention significantly reduced Aβ deposition in the cerebral cortex and hippocampus by 67% and 60%, respectively. It also ameliorated histopathological changes in the colon, reducing crypt depth and restoring goblet cell numbers. The expression of tight junction proteins Claudin-1 and ZO-1 was significantly upregulated, enhancing intestinal barrier integrity. Furthermore, NMN synbiotics decreased the expression of proinflammatory cytokines IL-1β, IL-6, and TNF-α, and reduced ROS levels, indicative of attenuated oxidative stress. The reduction in Aβ deposition, enhancement of intestinal barrier function, decrease in neuroinflammation, and alleviation of oxidative stress suggest that NMN synbiotics present a promising therapeutic intervention for AD by modulating multiple pathological pathways. Further research is required to elucidate the precise mechanisms, particularly the role of the NLRP3 inflammasome pathway, which may offer a novel target for AD treatment.

The activation of adenosine monophosphate-activated protein kinase inhibits the migration of tongue squamous cell carcinoma cells by targeting Claudin-1 via epithelial-mesenchymal transition.

The role of Claudin-1 in tongue squamous cell carcinoma (TSCC) metastasis needs further clarification, particularly its impact on cell migration. Herein, our study aims to investigate the role of Claudin-1 in TSCC cell migration and its underlying mechanisms. 36 TSCC tissue samples underwent immunohistochemical staining for Claudin-1. Western blotting and immunofluorescence analyses were conducted to evaluate Claudin-1 expression and distribution in TSCC cells. Claudin-1 knockdown cell lines were established using short hairpin RNA transfection. Migration effects were assessed through wound healing assays. Furthermore, the expression of EMT-associated molecules was measured via western blotting. Claudin-1 expression decreased as TSCC malignancy increased. Adenosine monophosphate-activated protein kinase (AMPK) activation led to increased Claudin-1 expression and membrane translocation, inhibiting TSCC cell migration and epithelial-mesenchymal transition (EMT). Conversely, Claudin-1 knockdown reversed these inhibitory effects on migration and EMT caused by AMPK activation. Our results indicated that AMPK activation suppresses TSCC cell migration by targeting Claudin-1 and EMT pathways.

Early-life supplementation with mannan-rich fraction to regulate rumen microbiota, gut health, immunity, and growth performance in dairy goat kids

Enhancing gastrointestinal health, immunity, and digestion are key factors to support dairy goat kid performance. Several additives have been studied in relation to these actions. This study investigated the impact of mannan-rich fraction (MRF) inclusion in goat milk on the growth performance, gut health, rumen fermentation, and microbial profiles of Xinong Saanen dairy goat kids. A total of 80 kids aged 14 d and 4.72 ± 0.33 kg BW were randomly assigned into 2 groups: control and MRF (1 g/d MRF mixed into milk). Each group consisted of 40 kids with 10 kids per pen. All kids were given milk individually and fed a starter diet by pen, with the trial lasting 10 wk. Body weight and blood samples were collected on the seventh day at 2, 6, 10 and 12 wk of age, and feed intake was determined daily. From the first to seventh day at 12 wk of age, fecal samples were collected from 4 kids in each group to analyze nutrient digestibility. On the seventh day of 12 wk of age, 4 kids from each group were slaughtered for evaluation of rumen fermentation, rumen microbiota, and gut morphology. The results indicated that MRF supplementation led to greater overall BW, overall starter DMI, and overall ADG, along with a lower overall diarrhea rate. However, no difference in overall feed efficiency and apparent digestibility of nutrients was observed. Furthermore, MRF supplementation resulted in increased ileal villus height; higher RNA expression of claudin-1 and occludin in the duodenum; higher expression of ZO-1, JAM-2, and occludin in the jejunum; and higher expression of claudin-1, JAM-2, and occludin in the ileum. Additionally, the concentrations of overall IgA, overall IgM, and overall IgG were higher in the MRF group. The concentrations of ruminal acetate and total volatile fatty acid were higher with MRF supplementation (P < 0.05). Meanwhile, supplementation with MRF resulted in higher abundance of Bacteroidetes and Succinivibrio and lower abundance of Firmicutes and Succiniclasticum in the rumen. Overall, the growth performance, gut health, immunity, and ruminal microbial structure of dairy goat kids benefited from MRF supplementation.