Tight Junction Damage Research Articles

Hypothermia-mediated oxidative stress induces immunosuppression, morphological impairment and cell fate disorder in the intestine of freshwater drum, Aplodinotus grunniens

The mechanism of the intestine in freshwater drum response to hypothermia exposure has not been investigated, despite the fact that it is a key organ of metabolism and immunity. Here, we conducted an 8-day hypothermia experiment under 10 °C to uncover the underlying mechanism in the intestine of freshwater drum. Morphologically, hypothermia exposure caused intestinal microvilli shortening, mitochondrial structure disruption, and tight junction damage. Physiologically, immunosuppression and inflammatory response were involved in the intestinal hypothermia response. According to transcriptome analysis, we discovered that hypothermia exposure induced apoptosis and ferroptosis in the intestine. Combined with correlation analyses, oxidative stress was considered critical in modifying the intestinal hypothermia response. In conclusion, hypothermia-induced oxidative stress leads to intestinal structure damage, immunosuppression and cell fate alterations, ultimately affecting the well-being of freshwater drum. This may provide some insights into hypothermia prevention in aquaculture management.

552 Quantifying the Blood-Brain Barrier in Acute Ischemic Stroke Using Novel MR Imaging

INTRODUCTION: Acute ischemic stroke causes endothelial cell and tight junction damage, resulting in blood-brain barrier (BBB) disruption. BBB disruption is a significant risk factor for hemorrhagic conversion, which is seen in up to 20-40% of patients, increasing mortality by 7.9-fold. A number of processes, such as reperfusion injury, neuroinflammation, and neoangiogenesis impact the BBB permeability, which can fluctuate for several weeks after stroke. Despite its significance, BBB permeability is not taken into consideration in the management of this patient population. METHODS: We used two MRI sequences, diffusion-prepared pseudocontinuous arterial spin labeling (DP-pCASL) and Neurite Orientation Dispersion and Density Imaging (NODDI) to scan patients greater than 18 years old who presented with acute ischemic stroke. DP-pCASL generates cerebral blood flow, arterial transit time (ATT), and BBB permeability. NODDI generates neurite dispersion index (NDI), orientation dispersion index (ODI), and free water index (ISO) maps. Normalized BBB permeability above the 75th percentile of the vascular territories was defined as high permeability. RESULTS: Ten patients were enrolled with a mean age of 66.8 ± 13.9 and NIHSS of 15.8 ± 8.0. Patients were scanned at a mean 83.4 ± 78.8 hours from symptom onset. Two patients had received alteplase and 6 patients underwent mechanical thrombectomy. Multivariable logistic regression showed that increasing ATT (p <0.001), decreasing ODI signal (p = 0.001), increasing relative monocyte count (p = 0.001) were significant predictors of increased BBB permeability. Intubation/general anesthesia decreased the odds of high BBB permeability (OR 0.072, p < 0.001). CONCLUSIONS: Higher ATT, higher monocyte count, lower ODI, and lack of anesthesia were significant predictors of high BBB permeability in stroke patients. We provide a detailed account of our addition of DP-pCASL and NODDI into the stroke imaging protocol.

Molecular Mechanisms Associated with Protecting IEC-6 Cells from Acrylamide-Induced Tight Junction Damage by Ganoderma atrum Polysaccharide.

The previous in vivo studies show Ganoderma atrum polysaccharide (PSG-F2 ) has a protective effect against the acrylamide (AA)-induced intestinal oxidative damage in rats. Now, this study aims to explore the protective mechanism with IEC-6 cell model. Based on RNA Sequencing (RNA-Seq), the study screens MAPK signaling pathway as one of the most crucial pathways for pretreatment with PSG-F2 against AA-induced damage in IEC-6 cells. In total, six key MAPK signaling pathway-related proteins (p-P38/P38, p-ERK/ERK, and p-JNK/JNK), and three tight junction key proteins (Zonula Occludens protein-1, Claudin-1, and Occludin) are detected by Western blot and immunofluorescence, which verify the RNA-Seq data. Moreover, PD98059 interference inhibits critical proteins in the MAPK signaling pathway, thus uncovering the precise molecular mechanisms of MAPK/ERK signaling pathway involve in the protective effects of PSG-F2 against AA-induced intestinal barrier damage. These findings confirm that PSG-F2 can be used as a daily dietary supplement to protect the intestinal cells from damage caused by thermal processing hazards AA.

Daidzein Protects Caco-2 Cells against Lipopolysaccharide-Induced Intestinal Epithelial Barrier Injury by Suppressing PI3K/AKT and P38 Pathways.

The intestinal epithelium provides an important barrier against bacterial endotoxin translocation, which can regulate the absorption of water and ions. The disruption of epithelial barrier function can result in water transport and tight junction damage, or further cause diarrhea. Therefore, reducing intestinal epithelial barrier injury plays an important role in diarrhea. Inflammatory response is an important cause of intestinal barrier defects. Daidzein improving the barrier integrity has been reported, but the effect on tight junction proteins and aquaporins is not well-described yet, and the underlying mechanism remains indistinct in the human intestinal epithelium. This study aimed to investigate the effects and mechanisms of daidzein on intestinal epithelial barrier injury induced by LPS, and a barrier injury model induced by LPS was established with human colorectal epithelial adenocarcinoma cell line Caco-2 cells. We found that daidzein protected the integrity of Caco-2 cell monolayers, reversed LPS-induced downregulation of ZO-1, occludin, claudin-1, and AQP3 expression, maintained intercellular junction of ZO-1, and suppressed NF-κB and the expression of inflammatory factors (TNF-α, IL-6). Furthermore, we found that daidzein suppressed the phosphorylation of the PI3K/AKT and P38 pathway-related proteins and the level of the related genes, and the PI3K/AKT and P38 pathway inhibitors increased ZO-1, occludin, claudin-1, and AQP3 expression. The study showed that daidzein could resist LPS-induced intestinal epithelial barrier injury, and the mechanism is related to suppressing the PI3K/AKT and P38 pathways. Therefore, daidzein could be a candidate as a dietary supplementation or drug to prevent or cure diarrhea.

Advances of tight junction damage in the corneal epithelial barrier in the pathogenesis of corneal diseases

The cornea is a transparent tissue with significant refractive and barrier functions. Corneal epithelium constitutes the first line of defense against foreign pathogens. Corneal epithelial cells interact to form a functionally selective permeability barrier. Dysfunction of this barrier leads to corneal impairment followed by a series of ocular surface diseases and even blindness. Tight junctions (TJ), located at the top of the intercellular space of corneal epithelial superficial cells, play a critical role in establishing and maintaining the barrier function. Previous studies have shown that destruction of the TJ acts as a crucial step of the occurrence and progression of multiple ocular surface diseases. Understanding the fundamental features and functions of the TJ, noticing the risk factors of TJ disruption, and clarifying the key role of TJ in the pathogenesis of various ocular surface diseases will help to better understand and treat ocular surface diseases.

Pharmacokinetic Differences of Wuji Pill Components in Normal and Chronic Visceral Hypersensitivity Irritable Bowel Syndrome Rats Attributable to Changes in Tight Junction and Transporters.

The Wuji pill, also called Wuji Wan (WJW), is an effective traditional medicine for the clinical treatment of irritable bowel syndrome (IBS). It is principally composed of Rhizoma Coptidis, Fructus Evodiae Rutaecarpae, and Radix Paeoniae Alba. There have been no reports on the pharmacokinetics of WJW on IBS. Because it is more meaningful to study pharmacokinetics in relation to specific pathological conditions, our study investigated the pharmacokinetic differences of five representative components (berberine, palmatine, evodiamine, rutaecarpine, and paeoniflorin) in normal rats and chronic visceral hypersensitivity IBS (CVH-IBS) model rats after single dose and multiple doses of WJW using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Transmission electron microscopy, immunohistochemistry, and immunofluorescence were used to explore mechanisms behind the pharmacokinetic differences in terms of tight junction proteins (Occludin and ZO-1), myosin light chain kinase (MLCK), and transporters including P-glycoprotein (P-gp), multidrug resistance associated protein 1 (MRP1), and multidrug resistance associated protein 2 (MRP2) in rat colons. After a single dose, for all components except rutaecarpine, significant differences were observed between normal and model groups. Compared with normal group, T1/2 and AUC0-t of berberine and palmatine in model group increased significantly (562.5 ± 237.2 vs. 1,384.9 ± 712.4 min, 733.8 ± 67.4 vs. 1,532.4 ± 612.7 min; 5,443.0 ± 1,405.8 vs. 9,930.8 ± 2,304.5 min·ng/ml, 2,365.5 ± 410.6 vs. 3,527.0 ± 717.8 min·ng/ml), while Cl/F decreased (840.7 ± 250.8 vs. 397.3 ± 142.7 L/h/kg, 427.7 ± 89.4 vs. 288.9 ± 114.4 L/h/kg). Cmax and AUC0-t of evodiamine in model group increased significantly (1.4 ± 0.6 vs. 2.4 ± 0.7 ng/ml; 573 ± 45.3 vs. 733.9 ± 160.2 min·ng/ml), while T1/2, Tmax, Cl/F, and Vd/F had no significant difference. Tmax and AUC0-t of paeoniflorin in model group increased significantly (21.0 ± 8.2 vs. 80.0 ± 45.8 min; 15,428.9 ± 5,063.6 vs. 33,140.6 ± 5,613.9 min·ng/ml), while Cl/F decreased (110.5 ± 48.1 vs. 43.3 ± 9.5 L/h/kg). However, after multiple doses, all five components showed significant differences between normal and model groups. Moreover, these differences were related to tight junction damage and the differential expression of transporters in the colon, suggesting that dose adjustment might be required during administration of WJW in the clinical treatment of IBS.

THU007 - Tight junction damage and increased gut permeability in alcohol-related liver disease may be mediated by gut proteases

THU007 - Tight junction damage and increased gut permeability in alcohol-related liver disease may be mediated by gut proteases

Porphyra tenera Protects against PM2.5-Induced Cognitive Dysfunction with the Regulation of Gut Function.

To evaluate the biological effects of Porphyra tenera (P. tenera), we tried to confirm the possibility that the intake of P. tenera could modulate cognitive and intestinal functions in PM2.5-induced cognitive decline mice. P. tenera attenuated PM2.5-induced learning and memory impairment through antioxidant and anti-inflammatory effects by regulating the mitochondrial function and TLR-initiated NF-κB signaling. In addition, P. tenera effectively alleviated Aβ production/tau phosphorylation by inhibiting the JNK phosphorylation. Also, the bioactive constituents of P. tenera determined the sulfated galactan, mycosporine-like amino acids (MAAs), and chlorophyll derivatives. Moreover, the bioactive compounds of P. tenera by gut fermentation protected against gut dysbiosis and intestinal tight junction damage with a decrease in inflammatory response and short-chain fatty acid production. Based on these results, our findings suggest that P. tenera with sulfated galactan and MAAs is a potential material for cognitive function improvement.

Autophagy regulates the effects of ADSC-derived small extracellular vesicles on acute lung injury

Small extracellular vesicles (sEVs) have been recognized to be more effective than direct stem cell differentiation into functional target cells in preventing tissue injury and promoting tissue repair. Our previous study demonstrated the protective effect of adipose-derived stem cells (ADSCs) on lipopolysaccharide (LPS)-induced acute lung injury and the effect of autophagy on ADSC functions, but the role of ADSC-derived sEVs (ADSC-sEVs) and autophagy-mediated regulation of ADSC-sEVs in LPS-induced pulmonary microvascular barrier damage remains unclear. After treatment with sEVs from ADSCs with or without autophagy inhibition, LPS-induced human pulmonary microvascular endothelial cell (HPMVECs) barrier damage was detected. LPS-induced acute lung injury in mice was assessed in vivo after intravenous administration of sEVs from ADSCs with or without autophagy inhibition. The effects of autophagy on the bioactive miRNA components of ADSC-sEVs were assessed after prior inhibition of cell autophagy. We found that ADSC-sEV effectively alleviated LPS-induced apoptosis, tight junction damage and high permeability of PMVECs. Moreover, in vivo administration of ADSC-sEV markedly inhibited LPS-triggered lung injury. However, autophagy inhibition, markedly weakened the therapeutic effect of ADSC-sEVs on LPS-induced PMVECs barrier damage and acute lung injury. In addition, autophagy inhibition, prohibited the expression of five specific miRNAs in ADSC-sEVs -under LPS-induced inflammatory conditions. Our results indicate that ADSC-sEVs protect against LPS-induced pulmonary microvascular barrier damage and acute lung injury. Autophagy is a positive mediator of sEVs function, at least in part through controlling the expression of bioactive miRNAs in sEVs.

GM130 protects against blood-brain barrier disruption and brain injury after intracerebral hemorrhage by regulating autophagy formation.

Blood-brain barrier (BBB) disruption following intracerebral hemorrhage (ICH) significantly contributes to neurological deficits. Tight junction (TJ) protein loss in brain endothelial cells leads to BBB disruption. We previously revealed the importance of the Golgi apparatus (GA) in maintaining TJ integrity in mouse brain endothelial (bEnd.3) cells, but the specific mechanisms remain unknown. Herein, we investigated the potential role of the GA in BBB damage and neurological dysfunction after ICH using bEnd.3 cells and hemin to mimic hemorrhage in vitro. We used a rat hemorrhage stroke model to evaluate the role of the GA in BBB disruption during ICH. GM130 levels decreased with ICH length in vivo and in vitro. TJ protein destruction further increased following GM130 silencing. GM130 overexpression alleviated TJ protein impairment and improved BBB integrity. bEnd.3 cells treated with an autophagy inhibitor showed reduced TJ protein damage following GM130 silencing. The intracerebroventricular injection of an autophagy inhibitor rescued GM130 silencing-induced BBB leakage. Thus, TJ proteins were destroyed by excessive autophagic pathway activation following ICH, whereas GM130 protected against TJ damage by maintaining proper autophagy. We suggest that GM130-regulated selective autophagy modulates BBB integrity and GM130 upregulation suppresses the autophagy-lysosome pathway, which might maintain BBB function. Therefore, GA protection is beneficial for ICH, and GM130 is a potential therapeutic target for its treatment.

Positive effects of Epigallocatechin-3-gallate (EGCG) intervention on insulin resistance and gut microbial dysbiosis induced by bisphenol A

Schematic illustration of ameliorative effects of EGCG on BPA-induced insulin resistance. • EGCG intervention successfully ameliorated insulin resistance and impaired insulin sensitivity induced by BPA exposure. • EGCG intervention restored serious damage of gut tight junctions. • EGCG effectively improved intestinal flora disorder and increased gut short chain fatty acids level. Bisphenol A (BPA), a plasticizer, is widely believed to cause metabolic disorders. However, an effective intervention is still absent. This study investigated the beneficial effects of Epigallocatechin-3-gallate (EGCG) on insulin resistance and microbial disturbance induced by BPA. The serum glucose, insulin, total triglyceride, and total cholesterol were decreased in BPA-treated mice after the intervention of EGCG. The sensitivity of insulin signals in peripheral tissue was improved by modulating the phosphorylation of IRS-1, Akt, and GSK-3β. In addition, 16S rRNA analysis for fecal microbiota showed the relative abundance of Ruminiclostridium , Blautia , unidentified_Ruminococcaceae , and Candidatus_Saccharimonas were restored by the high dose of EGCG. Furthermore, EGCG increased the concentrations of fecal short-chain fatty acids and protected the gut barrier impaired by BPA. Overall, our results demonstrated the positive effects of EGCG on BPA-induced insulin resistance and gut microbial dysbiosis. The current study provides a potential treatment for the chronic metabolic toxicity of BPA.

Multiple perspectives reveal the gut toxicity of polystyrene microplastics on Eisenia fetida: Insights into community signatures of gut bacteria and their translocation

The gut is the primary pathway by which soil animals are exposed to microplastics (MPs). However, the gut toxicity of MPs has not been elucidated in earthworms. Herein, we aimed to study the gut toxicity (e.g., gut barrier dysfunction, gut bacterial translocation, and pathogen invasion) of polystyrene microplastics (PS-MPs) on Eisenia fetida and its relationship with gut bacteria. We found that PS-MPs exposure caused gut barrier damage to Eisenia fetida. This damage included apparent injury of gut epithelial cells and significantly lower transcription levels of genes coding for gut tight junction (TJ)-related proteins. We then observed significantly increased levels of bacterial lipopolysaccharide (LPS) and gut bacterial load, indicating the occurrence of gut bacterial translocation and related barrier damage. Subsequently, antibacterial immune responses were activated and accompanied by a failure of the antioxidant defense system, indicating that pathogen invasion might occur. Gut barrier damage could weaken host selective pressures (deterministic process) on gut bacteria, such as particular pathogens. Indeed, members of Proteobacteria, e.g., Aeromonas and Escherichia/Shigella, regarded as potential opportunistic pathogens, were remarkable signatures of groups exposed to PS-MPs. These potential opportunistic gut bacteria were pivotal contributors to gut TJ damage and gut bacterial translocation resulting from PS-MPs exposure. In addition, the gut bacterial networks of PS-MPs exposure groups were more uncomplicated than those of the control group, but more negative interactions were easy to observe. In conclusion, our work sheds light on the molecular mechanism of earthworm gut toxicity caused by PS-MPs exposure and provides a prospective risk assessment of MPs in soil ecosystems.

Opioid Antagonist Nanodrugs Successfully Attenuate the Severity of Ischemic Stroke.

The United States is in the midst of an opioid epidemic that is linked to a number of serious health issues, including an increase in cerebrovascular events, namely, stroke. Chronic prescription opioid use exacerbates the risk and severity of ischemic stroke, contributing to stroke as the fifth overall cause of death in the United States and costing the US health care system over $30 billion annually. Pathologically, opioids challenge the integrity of the blood–brain barrier (BBB), resulting in a dysregulation of tight junction (TJ) proteins that are crucial in maintaining barrier homeostasis. Despite this, treatment options for ischemic stroke are limited, and there are no pharmacological options to attenuate TJ damage, including in incidents that are linked to opioid use. Herein, we have generated carrier-free, pure “nanodrugs” or nanoparticles of naloxone and naltrexone with enhanced therapeutic properties compared to the original (parent) drugs. The generated nanoformulations of both opioid antagonists exhibited successful attenuation of morphine- or oxycodone-induced alterations of TJ protein expression and reduced oxidative stress to a greater extent than the parent drugs (non-nano). As a proof of concept, we then proceeded to evaluate the therapeutic effectiveness of the generated nanodrugs in an ischemic stroke model of mice exposed to morphine or oxycodone. Our results demonstrate that the opioid antagonist nanoformulations reduced stroke severity in mice. Overall, this research implements advances in nanotechnology-based repurposing of FDA-approved therapeutics, and the obtained results also suggest underlying pharmacological mechanisms of opioid antagonists, further supporting these opioid antagonists and their respective nanoformulations as potential therapeutic agents for ischemic stroke.

Tight junction membrane protein's role in neural tube defects

More than 300,000 infants worldwide are born with neural tube defects (NTD), making it the second most common birth defect in the world. Many genetic and environmental factors have been identified as drivers of NTDs, some of which have been tied to damage of tight junctions (TJ), which are critical for the success of neural tube folding. Claudins (CLDN), occludin (OCLN) and junctional adhesion molecules (JAMs) are essential components of the TJ and are key players in its function. In the chicken embryo, clostridium perfringens enterotoxin (CPE) induces NTDs, by interacting broadly with CLDN3, ‐4, and ‐8. These interactions increase TJ permeability to an influx of calcium ions, causing cell death. There is no information for the role of OCLN or JAMs in NTDs. Our laboratory has created Synthetic Biology approaches to produce soluble CLDNs, OCLN and JAMs. These are detergent independent proteins that result in molecules that retain structure and adhesive properties of the native membrane protein. We present evidence that specific interactions, rather than the broad specificity of CPE, can be used to identify specific mechanisms leading to NTD formation. Our approach expands to the role of OCLN and JAMs in the formation of NTDs. These new tools may be used in developmental research as an alternative for genetic manipulation with equal value.

Carbon monoxide-releasing molecule-2 protects intestinal mucosal barrier function by reducing epithelial tight-junction damage in rats undergoing cardiopulmonary resuscitation

BackgroundIschemia-reperfusion injury (IRI) to the small intestine is associated with the development of systemic inflammation and multiple organ failure after cardiopulmonary resuscitation (CPR). It has been reported that exogenous carbon monoxide (CO) reduces IRI. This study aimed to assess the effects of carbon monoxide-releasing molecule-2 (CORM-2) on intestinal mucosal barrier function in rats undergoing CPR. MethodsWe established a rat model of asphyxiation-induced cardiac arrest (CA) and resuscitation to study intestinal IRI, and measured the serum levels of intestinal fatty acid-binding protein. Morphological changes were investigated using light and electron microscopes. The expression levels of claudin 3 (CLDN3), occludin (OCLN), zonula occludens 1 (ZO-1), tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), and nuclear factor kappa B (NF-κB) p65 were detected by western blotting. ResultsCompared with the sham-operated group, histological changes and transmission electron microscopy revealed severe intestinal mucosal injury in the CPR and inactive CORM-2 (iCORM-2) groups. In contrast, CORM-2 alleviated intestinal IRI. CORM-2, unlike iCORM-2, markedly decreased the Chiu's scores (2.38 ± 0.38 vs. 4.59 ± 0.34; P < 0.05) and serum intestinal fatty acid-binding protein level (306.10 ± 19.22 vs. 585.64 ± 119.84 pg/mL; P < 0.05) compared with the CPR group. In addition, CORM-2 upregulated the expression levels of tight junction proteins (CLDN3, OCLN, and ZO-1) (P < 0.05) and downregulated those of IL-10, TNF-α, and NF-кB p65 (P < 0.05) in the ileum tissue of rats that received CPR. ConclusionsCORM-2 prevented intestinal mucosal damage as a result of IRI during CPR. The underlying protective mechanism was associated with inhibition of ischemia-reperfusion-induced changes in intestinal epithelial permeability and inflammation in intestinal tissue.

NMMHC IIA triggered lipid metabolize reprogramming resulting in vascular endothelial cellular tight junction injury.

Nonmuscle myosin heavy chain IIA, played an essential role in the promotion of tight junction injury in vascular endothelial cells under oxygen glucose deprivation condition. Rat microvascular endothelial cells had been confirmed to have the susceptibility to ox-LDL stimulation under OGD condition. We proposed the hypothesis that lipid metabolic reprogramming might be the root cause for damage to RBMCs tight junction. Untargeted shotgun and targeted lipid metabolomics mass spectrometry approaches combined with principal component analysis was applied to better define the lipids contributing to the variance observed between control and different OGD time. The protein expression of tight junction of RBMCs: occludin, claudin-5, and ZO-1 were detected with immunofluorescence staining and western blot. The proof of the interaction between NMMHC IIA and SREBP1 was investigated via GST-pull down, while their specific binding fragments were also confirmed. The regulation mechanism of NMMHC IIA on SREBP1 was investigated to explore downstream regulatory signaling pathways. Untargeted and targeted shotgun lipidomics data revealed that OGD might be the conditional factor in reshaping lipid components. Mechanistic studies showed that with the increase of OGD time, PCA analysis of lipidomics obtained from RBMCs indicated their specificity in reshaping lipid components, while ≥80% major lipid components phospholipids and sphingolipids transferred from phospholipids, sphingolipids, and neutral lipids, of which neutrallipids taken the largest proportion with OGD time course. Perturbing reprogramming of lipid composition was less susceptible to OGD condition via knockdown of NMMHC IIA of vascular endothelial cells. Knockdown of NMMHC IIA could promote tight junction defense to OGD condition. NMMHC IIA could directly bind with SREBP1, then could affect sterol regulatory element binding protein-1 to adjust lipid metabolize reprogramming of RBMCs. Mechanistic studies showed that perturbing reprogramming of lipid composition could enhance tight junction damage, which was mediated by the opposing effects of NMMHC IIA.

The ameliorative effect of melatonin on LPS-induced Sertoli cells inflammatory and tight junctions damage via suppression of the TLR4/MyD88/NF-κB signaling pathway in newborn calf

The blood-testicular barrier (BTB) is involved in spermatogenesis, protects sperm development, and plays a crucial role in the reproductive process. Tight junctions (TJs) between Sertoli cells (SCs) are the key structure of (BTB), and if its structure is damaged, BTB function is affected. The cellular inflammation caused by Gram-negative bacteria affects the structural integrity of TJs. Melatonin (MT) has anti-inflammatory effects; however, the effect of MT in newborn calf SCs is unknown. Therefore, this experiment studied the protective effect of MT. The results showed that LPS upregulated TLR4, MyD88, and NF-κB expressions, in turn, activated the TLR4/MyD88/NF-κB signaling pathway, produced a large amount of IL-6 and IL-1β, downregulated the expression of ZO-1 and Occludin, and reduced the viability of SCs, which resulted in the inflammatory response of SCs and damage of TJs. The addition of MT decreased TLR4, MyD88, and NF-κB expressions, it then inhibited the activation of TLR4/MyD88/NF-κB signaling pathway, downregulated the expression of IL-6 and IL-1β, upregulated the expression of ZO-1 and Occludin, and increased the cell viability, thereby alleviating the inflammatory response of SCs, and restored the TJs structure. Overall, our results reveal that MT can alleviate LPS-induced in newborn calf SCs Inflammation and TJs injury through TLR4/MyD88/NF-κB signaling pathway.

Syndecan-1 Shedding by Matrix Metalloproteinase-9 Signaling Regulates Alveolar Epithelial Tight Junction in Lipopolysaccharide-Induced Early Acute Lung Injury.

IntroductionAlveolar epithelial tight junction damage and glycocalyx syndecan-1 (SDC-1) degrading are key factors to pulmonary edema of acute lung injury (ALI). Matrix metalloproteinase-9 (MMP-9) was involved in glycocalyx shedding, which was vital in SDC-1 degrading. This study aimed to investigate the effects of MMP-9-mediated SDC-1 shedding on tight junction in LPS-induced ALI.MethodsMice were intratracheally atomized with 5 mg/kg LPS to stimulate different periods and LPS stimulation for 6 hours for further studies. A549 cells was stimulated for 6 hours by active MMP-9 protein to assess the effects of active MMP-9 protein on SDC-1 and tight junction. Afterward, the mice treated with MMP-9 shRNA or A549 cells were treated with MMP-9 siRNA before LPS stimulation for 6 hours to explore the effects on glycocalyx SDC-1 and tight junction. Moreover, the mice were treated with recombinant SDC-1 protein or A549 cells were over-expressed by pc-SDC-1 before LPS stimulation for 6 hours to explore the effects of SDC-1 on tight junction.ResultsThe mice persistent exposure to LPS showed that MMP-9 expression, glycocalyx SDC-1 shedding (SDC-1 decreased in alveolar epithelium and increased in the BALF), tight junction impairment, FITC-albumin infiltration, and other phenomena began to appear after 6 hours of LPS treatment in this study. The levels of SDC-1 and tight junction significantly decreased by active MMP-9 protein stimulation for 6 hours in the A549 cells. Therefore, LPS stimulation for six hours was selected for investigating the underlying effects of MMP-9-mediated SDC-1 shedding on the alveolar epithelial tight junction and pulmonary edema. Further vivo analysis showed that down regulation MMP-9 expression by MMP-9 shRNA significantly alleviated glycocalyx SDC-1 shedding (SDC-1 increased in alveolar epithelium and decreased in the BALF), tight junction (occludin and ZO-1) damage, and FITC-albumin infiltration in LPS-induced early ALI mice. The vitro results also showed that MMP-9 siRNA alleviated glycocalyx SDC-1 shedding (SDC-1 increased in cell culture medium and decreased in cell surface) and tight junction damage by downregulating MMP-9 expression in LPS-stimulated A549 cells. In addition, pretreatment with recombinant mouse SDC-1 protein significantly alleviated glycocalyx (SDC-1 increased in alveolar epithelium) and tight junction damage, and FITC-albumin infiltration in LPS-induced early ALI mice. Overexpression SDC-1 by pc-SDC-1 also significantly decreased tight junction damage in LPS-stimulated A549 cells.ConclusionGlycocalyx SDC-1 shedding mediated by MMP-9 significantly aggravated tight junction damage, which further increased the pulmonary edema.

Effect of aspirin to intentionally induce leaky gut on performance, inflammation, and carcass characteristics of feedlot cattle

The negative impacts of stress on gastrointestinal tract (GIT) barrier function can result in compromised animal growth and health. Aspirin is known to cause mucosal injury leading to increased gut permeability and tight junction damage and can be used as a model to study leaky gut in cattle. The objective of this study was to determine the long-term impact of aspirin-induced chronic leaky gut on cattle growth and carcass attributes. Two treatments were evaluated in two studies: control (no aspirin) or 0.25% of the diet dry matter (DM) aspirin fed daily. Diets consisted of 50% corn, 24% dried distillers grains, 20% corn silage, and 6% supplement on a DM basis. In experiment 1, sixteen Angus × Simmental heifers, allotted by body weight (BW) and breed composition, were fed diets for 154 d. On day 155, heifers were dosed with 1 liter of a 180-mM Cr-ethylenediaminetetraacetic acid solution using an esophageal tube and had urine collected every 1.5 to 3 h for 48 h for analysis of Cr as a measure of gut leakiness. In experiment 2, ninety-six Simmental × Angus steers (355.0 ± 14.8 kg) were allotted by BW and breed composition and fed treatment diets for 159 d. Weight was recorded monthly and serum was collected on day 159 and analyzed for lipopolysaccharide-binding protein (LBP), interleukin-6 (IL-6), serum amyloid A (SAA), haptoglobin, and aspartate aminotransferase (AST). Data were analyzed using the MIXED procedure of SAS. Heifers fed 0.25% aspirin in experiment 1 excreted more Cr into urine compared with heifers not fed aspirin (overall treatment effect, P = 0.01). In experiment 2, aspirin tended to increase serum LBP (P = 0.06) but had no effect on concentrations of IL-6, haptoglobin, SAA, or AST (P ≥ 0.25). Aspirin tended to decrease average daily gain (P = 0.10), decreased hot carcass weight and rib-eye area (P ≤ 0.05), and increased fat thickness, marbling score, and yield grade (P ≤ 0.02). Aspirin tended to increase kidney, pelvic, and heart fat percentage (P = 0.10) and had no effect on liver abscesses (P ≥ 0.80). This study indicates that leaky gut induced by long-term administration of aspirin has negative impacts on feedlot performance and carcass composition. The negative impact of aspirin-induced leaky gut on animal performance suggests that chronic leaky gut caused by other factors (subacute acidosis, stress) may be a significant problem for the feedlot industry.

Piperine Improves Obesity by Inhibiting Fatty Acid Absorption and Repairing Intestinal Barrier Function

Currently, the weight loss effects of piperine have gained considerable attention; however, the underlying mechanism needs to be comprehensively elucidated. In the present study, we aimed to investigate the relationship between the weight loss effects of piperine and intestinal function. Based on the obtained results, piperine inhibited intestinal fatty acid absorption in both cellular and animal models. The underlying mechanism may be related to the downregulation of fatty acid absorption-related genes, fatty acid-binding protein 2 and cluster of differentiation 36, but not fatty acid transport protein 4. In addition, piperine repaired the tight junction damage induced by obesity by downregulating jejunal tumor necrosis factor-α and reducing lipopolysaccharide-induced damage on intestinal cell proliferation, thus enhancing intestinal barrier function, which is beneficial in reducing chronic inflammation associated with obesity. In conclusion, the anti-obesity effect of piperine is related to the enhancement of intestinal barrier function and inhibition of intestinal fatty acid absorption.