Expression Of Claudin-1 Research Articles

Claudin2 is involved in the interaction between Megalocytivirus-induced virus-mock basement membrane (VMBM) and lymphatic endothelial cells.

The genus Megalocytivirus, belonging to the family Iridoviridae, is one of the most detrimental virus groups to fish aquaculture. Megalocytivirus creates a virus-mock basement membrane (VMBM) on the surface of infected cells. This membrane provides attachment sites for lymphatic endothelial cells (LECs), disrupting fish's endothelial cell-extracellular matrix system. This disruption triggers injury to the vascular system and can result in death. Exploring the VMBM-cell interaction mechanism is crucial for uncovering the pathogenesis of Megalocytivirus and identifying therapeutic targets. Claudins, a class of tetra transmembrane proteins, play a key role in creating tight junctions between endothelial or epithelial cells. In this study, we demonstrated that the expression of Claudin2, a member of the Claudin family in fish, was significantly up-regulated by Megalocytivirus infection. Claudin2 was found in LECs attached to the surface of infected cells. It interacted with the VMBM viral components VP23R, VP08R, and VP33L at multiple binding sites through its two extracellular loops. However, it did not interact with the host basement membrane's nidogen. Therefore, Claudin2 is involved in the interaction of LEC with VMBM and plays a role in the disturbed distribution of extracellular matrix and endothelial cells in Megalocytivirus-infected fish tissues. This study aims to uncover the molecular mechanisms by which Megalocytivirus infection leads to pathological changes in the vascular system.

Regulatory Effect of Fucoidan Hydrolysates on Lipopolysaccharide-Induced Inflammation and Intestinal Barrier Dysfunction in Caco-2 and RAW264.7 Cells Co-Cultures

Fucoidan, a sulfated polysaccharide rich in fucose, is derived from brown algae and marine invertebrates. Multiple bioactivities have been shown with fucoidan, while growing attraction has emerged in its low-molecular-weight (Mw) hydrolysates. Here, the anti-inflammatory effect of fucoidan, low-Mw acidolyzed fucoidan (LMAF, <1.5 kDa), and high-Mw acidolyzed fucoidan (HMAF, 1.5–20 kDa) were investigated in vitro using lipopolysaccharide (LPS)-stimulated Caco-2 and RAW264.7 co-cultures. Fucoidan, LMAF, and HMAF with different structures exhibited varied anti-inflammatory effects. LMAF and HMAF effectively decreased the nitric oxide release of RAW264.7 cells. LMAF exhibited a competitive effect in reducing tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 levels compared to HMAF and fucoidan. Transcriptome of RAW264.7 revealed that LPS and LMAF mainly regulated the transcriptional expression of genes, including Tnf, Il6, Il1b, Junb, and Nfkb1 in the TNF signaling pathway, NF-kappa B signaling pathway, and cytokine–cytokine receptor interaction. RT-PCR results indicated that LMAF markedly reduced the LPS-elevated expression of Cxcl2, Tnf, Ccl2, Il1b, and Csf2. Moreover, LMAF effectively increased the proteins expression of Claudin-1, Occludin, and Zonula occluden-1 in Caco-2 cells. This study highlights the potential of LMAF to improve inflammation and intestinal barrier integrity, offering a foundation for further application of low-Mw fucoidan hydrolysates.

Experimental colitis is comorbid with social interaction deficits and anxiety-like behaviors in mice: mechanistic intuitions into neuroinflammation and Claudin 5 expression in the hippocampus.

Inflammatory bowel disease (IBD) is accompanied by psychiatric disorders, including Schizophrenic-like manifestations. Although incompletely illustrated, intestinal mucosal membrane damage and blood-brain barrier (BBB) penetrability may have significant roles in psychiatric symptoms of IBD. This study aimed to investigate role of the Claudin-5 (CLDN5) (a regulator of the permeability of BBB) and neuroinflammatory response in the comorbid behavioral disorders in experimental colitis in mice. Acetic acid was used to induce colitis in mice. 7 days after induction of colitis, behaviors including social interaction and locomotor activity as well as anxiety-like behaviors were evaluated. Then, the colon was extracted for gross and microscopic evaluations. The expression of CLDN5, TNF-α, IL1β and IL23 was measured by RT-PCR in the colon and hippocampus. Histopathologic evaluations demonstrated mucosal, submucosal, and crypt-related damages in the colon. The negative and positive number of social interactions significantly increased in the colitis group. A considerable increase in locomotor activities (horizontal and vertical components) shown in the colitis group. Mice in colitis group spent less time in the central zone in the open field apparatus. Gene expressions of TNF-α, IL1β, and IL23 increased and CLDN5 decreased in the colitis group. The barrier function of the intestine and brain would be impaired, partially at least, following colitis (as we observed decrease in CLDN5 gene expression). Furthermore, we found that beside inflammatory response in the colon, a neuro-immune response triggered in the hippocampus following colitis. These alterations probably, mediated comorbid behavioral disorders in acetic acid-induced colitis in mice.

Unveiling the therapeutic potential and mechanism of inulin in DSS-induced colitis mice

Inulin has been reported to alleviate colitis. In this study, colitis patients' feces were used to simulate fermentation to demonstrate changes in the microbiota profile in the presence of inulin. We found inulin can reshape the gut microbiota profile of colitis patients, especially by altering the abundance of Faecalibacterium and Blautia. Interestingly, the subsequent co-culture with inulin demonstrated that inulin promoted the growth of these two strains of bacteria. The dextran sodium sulfate (DSS)-induced mouse model was used to examine the effect of inulin and its combination with two probiotics on colitis. Results showed that all three treatments can alleviate the clinical symptoms, including weight-losing, colon-shortening, and the Disease Activity Index (DAI) score. Further investigations showed that the administrations regulate colitis mice's pro- and anti-inflammatory cytokines, such as TNF-α, IL-1β, IL-6, IL-10, and IL-17. Also, they alter the relative abundance of Faecalibacterium and Blautia, change the short-chain fatty acids (SCFAs) profile in the cecum and colon, and improve the intestinal barrier; specifically, the intervention increased the expressions of Claudin, Occludin, Zonula Occludens (ZO)-1, and Mucin (MUC)-2 in colonic tissues, thus restoring the colonic tissue structure and morphology of colitis mice. Collectively, our results confirm that inulin can alter the colitis patients' characteristic microbial community, and they can ameliorate experimental colitis by inhibiting the TRL4/MyD88/NF-κB signaling pathway—improving the inflammatory response and enhancing the intestinal barrier. In conclusion, we propose that inulin may hold promise as a functional food therapeutic approach for the treatment of colitis.

Effects of Eimeria challenge on growth performance, intestine integrity, and cecal microbial diversity and composition of yellow broilers

The invasion of Eimeria causes damage to the intestinal barrier, nutrient leakage, and microbial imbalance in poultry. We aimed to investigate the effects of Eimeria infection on growth performance, intestinal integrity, and cecal microbial diversity and composition of yellow broilers. A total of 180 male yellow broilers were randomly divided into an unchallenged control and an Eimeria challenge treatment group within 18 floor pens (10 chicks/pen, 9 replicate pens/group). On day 10, 90 chicks received a cocktail of E. maxima, E. acervulina, and E. tenella oocysts (105/chick) to induce coccidial infection, and the other 90 received an aliquot of PBS. The Eimeria challenge resulted in increased bird feed consumption and FCR from day 11 to 21 (all P < 0.01). Higher fecal Eimeria counts, duodenal, jejunal, and cecal lesions were observed in the challenge group on day 12, 15, 15, 18 respectively (all P < 0.05). Furthermore, the infected birds had larger livers and small intestines, deeper villus crypt, and decreased expression of Claudin-1 on day 21 (all P < 0.05). The 16S rRNA sequencing indicated that alpha diversity (Sobs, Shannon, Simpson, Ace, or Chao) of cecal microbials was not affected by Eimeria challenge (all P > 0.05). However, the PCoA and LEfSe analyses indicated that the Eimeria challenge altered microbial distribution by decreasing the abundance of Firmicutes and enriching the abundance of Proteobacteria at the phylum level. At the genus level, Clostridia vadin BB60 and Lachnospiraceae NK4A136 group were reduced, while Escherichia-Shigella were enriched in the challenged yellow broilers (all P < 0.05). Correlation analyses demonstrated that the birds with higher Lachonospiraceae NK4A136 group and Clostridia vadin BB60, and lower Escherichia-Shigella in their cecal content gained more BW and reached a lower FCR from day 11 to 21 (all P < 0.05). In conclusion, Eimeria infection compromised feed efficiency of yellow broilers by damaging intestinal barrier and shifting cecal microbiota towards colonizers associated with poor performance. Restoring the dysbiotic microbiome could be a potential strategy for improving feed efficiency in yellow broilers under coccidial challenge.

Neurons enhance blood–brain barrier function via upregulating claudin-5 and VE-cadherin expression due to glial cell line-derived neurotrophic factor secretion

Blood–brain barrier (BBB) prevents neurotoxins from entering central nervous system. We aimed to establish and characterize an in vitro triple co-culture BBB model consisting of brain endothelial cells hCMEC/D3, astrocytoma U251 cells, and neuroblastoma SH-SY5Y cells. Co-culture of SH-SY5Y and U251 cells markedly enhanced claudin-5 and VE-cadherin expression in hCMEC/D3 cells, accompanied by increased transendothelial electrical resistance and decreased permeability. Conditioned medium (CM) from SH-SY5Y cells (S-CM), U251 cells (U-CM), and co-culture of SH-SY5Y and U251 cells (US-CM) also promoted claudin-5 and VE-cadherin expression. Glial cell line-derived neurotrophic factor (GDNF) levels in S-CM and US-CM were significantly higher than CMs from hCMEC/D3 and U-CM. Both GDNF and US-CM upregulated claudin-5 and VE-cadherin expression, which were attenuated by anti-GDNF antibody and GDNF signaling inhibitors. GDNF increased claudin-5 expression via the PI3K/AKT/FOXO1 and MAPK/ERK pathways. Meanwhile, GDNF promoted VE-cadherin expression by activating PI3K/AKT/ETS1 and MAPK/ERK/ETS1 signaling. The roles of GDNF in BBB integrity were validated using brain-specific Gdnf silencing mice. The developed triple co-culture BBB model was successfully applied to predict BBB permeability. In conclusion, neurons enhance BBB integrity by upregulating claudin-5 and VE-cadherin expression through GDNF secretion and established triple co-culture BBB model may be used to predict drugs’ BBB permeability.

Neurons enhance blood-brain barrier function via upregulating claudin-5 and VE-cadherin expression due to glial cell line-derived neurotrophic factor secretion.

Blood-brain barrier (BBB) prevents neurotoxins from entering central nervous system. We aimed to establish and characterize an in vitro triple co-culture BBB model consisting of brain endothelial cells hCMEC/D3, astrocytoma U251 cells, and neuroblastoma SH-SY5Y cells. Co-culture of SH-SY5Y and U251 cells markedly enhanced claudin-5 and VE-cadherin expression in hCMEC/D3 cells, accompanied by increased transendothelial electrical resistance and decreased permeability. Conditioned medium (CM) from SH-SY5Y cells (S-CM), U251 cells (U-CM), and co-culture of SH-SY5Y and U251 cells (US-CM) also promoted claudin-5 and VE-cadherin expression. Glial cell line-derived neurotrophic factor (GDNF) levels in S-CM and US-CM were significantly higher than CMs from hCMEC/D3 and U-CM. Both GDNF and US-CM upregulated claudin-5 and VE-cadherin expression, which were attenuated by anti-GDNF antibody and GDNF signaling inhibitors. GDNF increased claudin-5 expression via the PI3K/AKT/FOXO1 and MAPK/ERK pathways. Meanwhile, GDNF promoted VE-cadherin expression by activating PI3K/AKT/ETS1 and MAPK/ERK/ETS1 signaling. The roles of GDNF in BBB integrity were validated using brain-specific Gdnf silencing mice. The developed triple co-culture BBB model was successfully applied to predict BBB permeability. In conclusion, neurons enhance BBB integrity by upregulating claudin-5 and VE-cadherin expression through GDNF secretion and established triple co-culture BBB model may be used to predict drugs' BBB permeability.

High-concentrate diet supplemented with hydrolysable tannin improves the slaughter performance, intestinal antioxidant ability and barrier function of fattening lambs

The objective of current experiment was to study the potential influence of hydrolysable tannin supplementation on slaughter performance, meat quality, intestinal digestive enzyme activity, antioxidant ability and barrier function in fattening lambs. In total, 36 male Hu sheep lambs with similar body weight (15.83 ± 0.48 kg) and days in age (55 ± 2 d) were randomly assigned to one of three groups of 12 animals each: control without tannin (CON) and tannin supplementation groups (TA1, 3 g/d per lamb; TA2, 6 g/d per lamb). All the lambs were reared in individual hutches, and the experiment lasted for 60 d. On d 61, 8 lambs from each group were randomly selected to slaughter. Results showed that the serum diamine oxidase and lipopolysaccharide contents of TA2 group were higher (p &amp;lt; 0.05) than those of CON group. Compared with CON group, the carcass weight and intramuscular fat content of lambs in TA1 group were increased (p &amp;lt; 0.05) and the meat shear force was decreased (p &amp;lt; 0.05). The trypsin activity in the jejunum and ileum of TA1 group was higher (p &amp;lt; 0.05) than that of CON and TA2 groups. Also, tannin supplementation significantly increased (p &amp;lt; 0.05) the level of jejunal and ileal total antioxidant capacity and reduced (p &amp;lt; 0.05) the jejunal malondialdehyde concentration in lambs. The jejunum and ileum of TA1 lambs showed reduced (p &amp;lt; 0.05) tumor necrosis factor-alpha and increased (p &amp;lt; 0.05) interleukin-10 mRNA levels compared with CON lambs. In the jejunum, the secretory immunoglobulin A content of TA1 group was higher (p &amp;lt; 0.05) than that of CON and TA2 groups. Lambs supplemented with tannin at the level of 3 g/d increased (p &amp;lt; 0.05) the gene expressions of claudin-1, claudin-4 and zonula occludens-1 in the jejunum when compared to those of CON and TA2 groups. In summary, tannin supplementation at the level of 3 g/d per animal can improve the production performance and intestinal function of fattening lambs fed a high-concentrate diet.

Protective Effect of Protocatechuic Aldehyde on Cerebral Ischemia/Reperfusion Injury in Rats through Blood-Brain Barrier Protection.

Cerebral ischemia can lead to destruction of the blood-brain barrier (BBB), the main cause of cerebral edema and cerebral infarction. BBB damage is also one of the key factors affecting the result of drug therapy. We studied the protective effect of 5-day pretreatment with protocatechuic aldehyde (PAL) at doses of 10 and 20 mg/kg on BBB function and structure after middle cerebral artery occlusion/reperfusion (MCAO/R) in rats. The infarct volume, behavioral neurological deficit score, and Evans blue content in the brain were estimated. We also evaluated the content of nitric oxide (NO) and activities of inducible and neuronal NO synthases. Expression of aquaporin-4 (AQP-4), occludin, claudin-5, and MMP-3 in the brain tissues was estimated by Western blotting. The BBB ultrastructure was analyzed under an electron microscope. We revealed that PAL at both used doses significantly reduced the neurological deficit score, brain infarct volume, and Evans blue extravasation. Electron microscopy showed that PAL significantly improved the ultrastructure of BBB and alleviated its injury. Pretreatment with PAL increased expression of occludin and claudin-5 and reduced expression of AQP-4 and MMP-3. At the same time, the release of NO and activities of NO synthases were notably inhibited. Our results suggest that PAL can be a promising compound to attenuate cerebral ischemia resulting from occlusion/reperfusion injury via BBB protection.

FMT and TCM to treat diarrhoeal irritable bowel syndrome with induced spleen deficiency syndrome- microbiomic and metabolomic insights

BackgroundDiarrheal irritable bowel syndrome (IBS-D) is a functional bowel disease with diarrhea, and can be associated with common spleen deficiency syndrome of the prevelent traditional Chinese medicine (TCM) syndrome. Fecal microbiota transplantation (FMT) could help treating IBS-D, but may provide variable effects. Our study evaluated the efficacy of TCM- shenling Baizhu decoction and FMT in treating IBS-D with spleen deficiency syndrome, with significant implications on gut microbiome and serum metabolites.MethodsThe new borne rats were procured from SPF facility and separated as healthy (1 group) and IBS-D model ( 3 groups) rats were prepared articially using mother’s separation and senna leaf treatment. 2 groups of IBS-D models were further treated with TCM- shenling Baizhu decoction and FMT. The efficacy was evaluated by defecation frequency, bristol stool score, and intestinal tight junction proteins (occludin-1 and claudin-1) expression. Microbiomic analysis was conducted using 16 S rRNA sequencing and bioinformatics tools. Metabolomics were detected in sera of rats by LC-MS and annotated by using KEGG database.ResultsSignificant increment in occludin-1 and claudin-1 protein expression alleviated the diarrheal severity in IBS-D rats (P < 0.05) after treatment with FMT and TCM. FMT and TCM altered the gut microbiota and regulated the tryptophan metabolism, steroid hormone biosynthesis and glycerophospholipid metabolism of IBS-D rats with spleen deficiency syndrome.The microbial abundance were changed in each case e.g., Monoglobus, Dubosiella, and Akkermansia and othe metabolic profiles.ConclusionFMT and TCM treatment improved the intestinal barrier function by regulating gut microbiota and improved metabolic pathways in IBS-D with spleen deficiency syndrome.

Neuroprotective effects of Daphnetin on hippocampal neurons and blood-brain barrier integrity in a mouse model of cerebral ischemia

The purpose of this research was to assess the impact of different doses of Daphnetin (DAP, a natural compound derived from coumarin) on hippocampus neuronal injury, neurobehavioral function, blood-brain barrier (BBB) integrity, expression of claudin-5, brain-derived neurotrophic factor (BDNF), superoxide dismutase (SOD), and inflammatory markers in a mouse model of cerebral ischemia. Cerebral ischemia was induced in mice through 30 minutes of bilateral common carotid occlusion (BCCAO), followed by 48 hours of reperfusion. The viability of hippocampal neurons was assessed using Cresyl violet staining and BBB function was determined by measuring Evans blue (E.B) dye leakage. Spatial memory was tested using the Radial Arm Water Maze (RAWM) task. Claudin-5 and BDNF were measured by immunofluorescence, while SOD, interleukin-1 beta (IL-1β), and nuclear factor-κB (NF-κB) expression were determined through western blotting. Administering DAP significantly increased neuron survival in the hippocampus CA1, CA3, and dentate gyrus (DG) regions and improved spatial memory dose-dependently (P<0.0001). Treatment with DAP (40 mg/kg IP) significantly reduced E.B leakage and brain water content (P<0.001). Furthermore, it increased the claudin-5, BDNF, and SOD levels and diminished NF-κB and IL-1β expression (P<0.0001). The research found that DAP protected neurons in the CA1, CA3, and DG areas of the hippocampus, enhanced behavioral functions, and preserved BBB integrity in a cerebral ischemia model. This positive impact is achieved by increasing the expression of claudin-5, BDNF, and SOD and diminishing neuroinflammation. Further research is required to clarify the mechanisms and possible clinical uses.

Glucocorticoid-Induced Leucine Zipper Protein and Yeast-Extracted Compound Alleviate Colitis and Reduce Fungal Dysbiosis

Inflammatory bowel diseases (IBD) have a complex, poorly understood pathogenesis and lack long-lasting effective treatments. Recent research suggests that intestinal fungal dysbiosis may play a role in IBD development. This study investigates the effects of the glucocorticoid-induced leucine zipper protein (GILZp)”, known for its protective role in gut mucosa, and a yeast extract (Py) with prebiotic properties, either alone or combined, in DSS-induced colitis. Both treatments alleviated symptoms via overlapping or distinct mechanisms. In particular, they reduced the transcription levels of pro-inflammatory cytokines IL-1β and TNF-α, as well as the expression of the tight junction protein Claudin-2. Additionally, GILZp increased MUC2 transcription, while Py reduced IL-12p40 and IL-6 levels. Notably, both treatments were effective in restoring the intestinal burden of clinically important Candida and related species. Intestinal mycobiome analysis revealed that they were able to reduce colitis-associated fungal dysbiosis, and this effect was mainly the result of a decreased abundance of the Meyerozima genus, which was dominant in colitic mice. Overall, our results suggest that combined treatment regimens with GILZp and Py could represent a new strategy for the treatment of IBD by targeting multiple mechanisms, including the fungal dysbiosis.

Micro RNA-175 Targets Claudin-1 to Inhibit Madin–Darby Canine Kidney Cell Adhesion

Background: The Madin–Darby canine kidney (MDCK) cell line constitutes a key component of influenza vaccine production, but its dependence on adherent growth limits cell culture density and hinders vaccine yield. There is evidence that the use of gene editing techniques to inhibit cell adhesion and establish an easily suspended cell line can improve vaccine yield; however, the mechanisms underlying MDCK cell adhesion are unclear. Methods: In this study, we used transcriptomics to analyse differentially expressed mRNAs and miRNAs in adherent and suspension cultures of MDCK cells. Results: We found that claudin-1 (CLDN1) expression was downregulated in the suspension MDCK cells and that CLDN1 promotes MDCK cell–extracellular matrix adhesion. Additionally, microRNA (miR)-175 expression was upregulated in the suspension MDCK cells. Importantly, we demonstrated that miR-175 inhibits MDCK cell adhesion by targeting the CLDN1 3′-untranslated region (UTR). These findings contribute to a more comprehensive understanding of the regulatory mechanisms modulating cell adhesion and provide a basis for establishing suspension-adapted, genetically engineered cell lines. Our work could also facilitate the identification of targets for tumour therapy.

Jianpi-Huatan-Huoxue-Anshen formula ameliorates gastrointestinal inflammation and microecological imbalance in chemotherapy-treated mice transplanted with H22 hepatocellular carcinoma.

Jianpi-Huatan-Huoxue-Anshen formula [Tzu-Chi cancer-antagonizing & life-protecting II decoction (TCCL)] is a Chinese medical formula that has been clinically shown to reduce the gastrointestinal side effects of chemotherapy in cancer patients and improve their quality of life. However, its effect and mechanism on the intestinal microecology after chemotherapy are not yet clear. To discover the potential mechanisms of TCCL on gastrointestinal inflammation and microecological imbalance in chemotherapy-treated mice transplanted with hepatocellular carcinoma (HCC). Ninety-six mice were inoculated subcutaneously with HCC cells. One week later, the mice received a large dose of 5-fluorouracil by intraperitoneal injection to establish a HCC chemotherapy model. Thirty-six mice were randomly selected before administration, and feces, ileal tissue, and ileal contents were collected from each mouse. The remaining mice were randomized into normal saline, continuous chemotherapy, Yangzheng Xiaoji capsules-treated, and three TCCL-treated groups. After treatment, feces, tumors, liver, spleen, thymus, stomach, jejunum, ileum, and colon tissues, and ileal contents were collected. Morphological changes, serum levels of IL-1β, IL-6, IL-8, IL-10, IL-22, TNF-α, and TGF-β, intestinal SIgA, and protein and mRNA expression of ZO-1, NF-κB, Occludin, MUC-2, Claudin-1, and IκB-α in colon tissues were documented. The effect of TCCL on the abundance and diversity of intestinal flora was analyzed using 16S rDNA sequencing. TCCL treatment improved thymus and spleen weight, thymus and spleen indexes, and body weight, decreased tumor volumes and tumor tissue cell density, and alleviated injury to gastric, ileal, and colonic mucosal tissues. Among proteins and genes associated with inflammation, IL-10, TGF-β, SIgA, ZO-1, MUC-2, and Occludin were upregulated, whereas NF-κB, IL-1β, IL-6, TNF-α, IL-22, IL-8, and IκB-α were downregulated. Additionally, TCCL increased the proportions of fecal Actinobacteria, AF12, Adlercreutzia, Clostridium, Coriobacteriaceae, and Paraprevotella in the intermediate stage of treatment, decreased the proportions of Mucipirillum, Odoribacter, RF32, YS2, and Rikenellaceae but increased the proportions of p_Deferribacteres and Lactobacillus at the end of treatment. Studies on ileal mucosal microbiota showed similar findings. Moreover, TCCL improved community richness, evenness, and the diversity of fecal and ileal mucosal flora. TCCL relieves pathological changes in tumor tissue and chemotherapy-induced gastrointestinal injury, potentially by reducing the release of pro-inflammatory factors to repair the gastrointestinal mucosa, enhancing intestinal barrier function, and maintaining gastrointestinal microecological balance. Hence, TCCL is a very effective adjuvant to chemotherapy.

Capsaicin attenuates the effect of inflammatory cytokines in a HaCaT cell model for basal keratinocytes.

The resolution of the skin's inflammatory response is only possible if its barrier function is restored. TRPV1 channel activation plays an important role during inflammation but the effect of this activation on the skin barrier under inflammatory conditions has not been clarified. We hypothesize that it could potentially aid the keratinocyte barrier by reducing inflammatory cytokine release and promoting tight junction development. To explore the role of TRPV1 activation in inflammation, we designed and optimized an in vitro model of keratinocytes with basal epidermal layer characteristics using HaCaT cells and TNFα to induce inflammation. TNFα increased the gene expression of tight junction protein claudin 1 (CLDN1) by at least 2.60 ± 0.16-fold, in a concentration-dependent manner, over a 48h period. The administration of a capsaicin pre-treatment reduced the CLDN1 expression to 1.51 ± 0.16-fold during the first 6h after TNFα induction, whereas IL-8 cytokine release was reduced 0.64 ± 0.17-fold. After 48h, CLDN1 protein levels increased by a factor of 6.57 ± 1.39 compared to cells only treated with TNFα. These results suggest that activation of TRPV1 by capsaicin can potentiate the increase in CLDN1 expression and CLDN1 protein synthesis induced by TNFα in cultured keratinocytes, while reducing the release of IL-8.

Cadmium Induces Vascular Endothelial Cell Detachment by Downregulating Claudin-5 and ZO-1 Levels.

Cadmium is a contributing factor to cardiovascular diseases and highly toxic to vascular endothelial cells. It has a distinct mode of injury, causing the de-endothelialization of regions in the monolayer structure of endothelial cells in a concentration-dependent manner. However, the specific molecules involved in the cadmium toxicity of endothelial cells remain unclear. The purpose of this study was to identify the specific molecular mechanisms through which cadmium affects endothelial detachment. Cadmium inhibited the expression of claudin-5 and zonula occludens (ZO)-1, which are components of tight junctions (strongest contributors to intercellular adhesion), in a concentration- and time-dependent manner. Compared to arsenite, zinc, and manganese, only cadmium suppressed the expression of both claudin-5 and ZO-1 molecules. Moreover, the knockdown of claudin-5 and ZO-1 exacerbated cadmium-induced endothelial cell injury and expansion of the detachment area, whereas their overexpression reversed these effects. CRE-binding protein inhibition reduced cadmium toxicity, suggesting that CRE-binding protein activation is involved in the cadmium-induced inhibition of claudin-5 and ZO-1 expression and endothelial detachment. These findings provide new insights into the toxicological mechanisms of cadmium-induced endothelial injury and risk of cardiovascular disease.

Didymin Ameliorates Dextran Sulfate Sodium (DSS)-Induced Ulcerative Colitis by Regulating Gut Microbiota and Amino Acid Metabolism in Mice.

Background: Didymin is a dietary flavonoid derived from citrus fruits and has been shown to have extensive biological functions, especially anti-inflammatory effects, but its mechanism is unclear. The purpose of this study was to investigate the potential mechanism of didymin that alleviates ulcerative colitis. Methods and Results: Our results indicated that didymin could alleviate the symptoms of ulcerative colitis, as it inhibited the expressions of interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Didymin also promoted the expressions of claudin-1 and zona occludens-1(ZO-1), which are closely related with restoring colon barrier function. Didymin also increased the abundance of Firmicutes and Verrucomicobiota, while decreasing the abundance of Bacteroidota and Proteobacteria. Meanwhile, didymin significantly altered the levels of metabolites related to arginine synthesis and metabolism, and lysine degradation in the colitis mice. Utilizing network pharmacology and molecular docking, our results showed that the metabolites L-ornithine and saccharin could interact with signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa-B (NF-κB). In this in vitro study, L-ornithine could reduce the expressions of transcription factors STAT3 and NF-κB, and it also inhibited the expressions of IL-6 and IL-1β in the lipopolysaccharides (LPS) induced in RAW264.7 cells, while saccharin had the opposite effect. Conclusions: Taken together, didymin can regulate gut microbiota and alter metabolite products, which can modulate STAT3 and NF-κB pathways and inhibit the expressions of inflammatory factors and inflammatory response in the DSS-induced colitis mice.

Correction: Toivio et al. Ketogenic Diet High in Saturated Fat Promotes Colonic Claudin Expression without Changes in Intestinal Permeability to Iohexol in Healthy Mice. Nutrients 2024, 16, 18

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Taurine enhances growth performance by improving intestinal integrity and antioxidant capacity of weaned piglets.

Taurine is an amino acid that has been considered by animal husbandry as a feed additive due to its abundant biological functions. However, the effective dose of taurine added to feed is unknown. The aim of current study was to determine the optimal taurine supplementation level by investigating its effects on growth performance, diarrhea index, intestinal health and antioxidant capacity of weaned piglets. A total of 160 crossbred piglets (Landrace × Yorkshire, initially 8.39 ±0.11kg) were assigned to 4 groups (10 pigs/pen and 4 replicates/group). Basal diets containing 0 (control, CON), 0.1%, 0.3%, and 0.5% taurine were respectively provided to the piglets for a duration of 28 days. Six piglets from each group were selected for euthanasia and subsequent sample collection on day 29. The results showed that dietary 0.3% or 0.5% taurine supplementation increased average daily gain (P < 0.05), feed to gain ratio (P < 0.01), and serum albumin (P < 0.05), and decreased diarrhea index (P < 0.01) and diamine oxidase (DAO) level in the serum (P < 0.05). The greater expression of tight junction-related genes, including ZO-1 (P < 0.05) and Claudin-1 (P < 0.01), were observed in the duodenum after supplementation with 0.5% taurine. The supplementation of 0.3% or 0.5% taurine resulted in a significant reduction of crypt depth (P < 0.01) and an increase of villus height-to-crypt depth ratio (P < 0.01) in the duodenum. A greater abundance of goblet cells was detected in the duodenum and jejunum of piglets fed 0.5% taurine (P < 0.05). In addition, serum superoxide dismutase (SOD) level, liver catalase (CAT) level and liver total antioxidant capacity level were all significantly (P < 0.05) increased with 0.1%, 0.3% or 0.5% dietary taurine supplementation. On the whole, dietary supplementation with 0.3% or 0.5% taurine has the potential to significantly enhance the growth performance of piglets by improving the integrity of the intestinal barrier and boosting their antioxidant capacity.

Metformin modulates the TXNIP-NLRP3-GSDMD pathway to improve diabetic bladder dysfunction

To validate the therapeutic efficacy of metformin on diabetic bladder dysfunction (DBD) and further elucidate whether the TXNIP-NLRP3-GSDMD axis serves as a target for metformin in ameliorating DBD. C57BL/6J mice were induced with diet-induced obesity by being fed a high-fat diet (HFD) for 16 weeks. After establishing the model, the mice were treated with metformin for 4 weeks, and their glucose metabolism-related parameters were assessed. Urine spot assays and urodynamic measurements were conducted to reflect the bladder function and urinary behavior in mice, while histological examination was performed to observe morphological changes. Western blot analysis was employed to measure the expression levels of pyroptotic factors such as TXNIP, NLRP3, GSDMD, and tight junction proteins. Metformin treatment significantly improved glucose tolerance and insulin sensitivity in mice. Moreover, it showed promise in decreasing urinary spot occurrence, reducing urination frequency, alleviating non-voiding contractions, and stabilizing peak urinary pressure. Following metformin therapy, mice displayed restored epithelial fold structure, increased thickness of the muscular layer, substantial decrease in muscle fiber content, notably reduced levels of TXNIP and GSDMD proteins in the metformin-treated group compared to the DBD group, and restored expression of tight junction proteins Zo-1, Claudin-1, and Occludin. Metformin ameliorates urothelial cells damage in DBD mice by inhibiting TXNIP generation and reducing NLRP3 and GSDMD production.