Tight Junction Proteins Claudin-1 Research Articles

Berberine mitigates diclofenac-induced intestinal mucosal mechanical barrier dysfunction through the restoration of autophagy by inhibiting exosome-mediated lncRNA H19.

Small intestine damage caused by diclofenac is called diclofenac enteropathy. Berberine (BBR), a class of isoquinoline alkaloids derived from Berberis vulgaris and Phellodendron amurense, is widely used in intestinal diseases. The present study evaluated the protective effect of BBR on the intestinal mucosal mechanical barrier in diclofenac enteropathy and its possible action mechanism. The in vitro animal experiment revealed that BBR downregulated the expression of long non-coding RNA H19 (lncRNA H19) in the small intestine and exosomes. In the co-culture experiment involving exosomes and intestinal epithelial cell-6(IEC-6) cells, the results of qRT-PCR, western blotting, and immunofluorescence assays demonstrated that the elevated expression of lncRNA H19 in the small intestine, conveyed via exosomes derived from the diclofenac group, suppressed the expression levels of autophagy-associated protein 5 (Atg 5) and light chain 3 (LC 3), as well as and the tight junction (TJ) proteins zonula occludens-1 (ZO-1), claudin-1, and occluding, relative to the control group. BBR treatment attenuated exosomal lncRNA H19 levels, upregulated the expression of Atg5 and LC3 expression, enhanced TJ protein expression, and increased the light chain 3 (LC3)-II/LC3-I ratio. These findings significantly elucidated that BBR promoted the restoration of autophagy in IECs by inhibiting exosomal lncRNA H19, thereby mitigating the impairment of the intestinal mucosal mechanical barrier function in diclofenac enteropathy. The process involving exosomal lncRNA H19 regulating autophagy, thereby affecting the intestinal mucosal mechanical barrier, offers a novel perspective for the application of BBR in the treatment of diclofenac enteropathy.

MRGPRX2 antagonist GE1111 attenuated DNFB-induced atopic dermatitis in mice by reducing inflammatory cytokines and restoring skin integrity

IntroductionAtopic dermatitis (AD) is a chronic inflammatory skin disorder characterised by itching, erythema, and epidermal barrier dysfunction. The pathogenesis of AD is complex and multifactorial; however,mast cell (MC) activation has been reported to be one of the crucial mechanisms in the pathogenesis of AD. The MC receptor Mas related G protein-coupled receptor-X2 (MRGPRX2) has been identified as a prominent alternative receptor to the IgE receptor in causing MC activation and the subsequent release of inflammatory mediators. The current study aimed to evaluate the therapeutic effect of a novel small molecule MRGPRX2 antagonist GE1111 in AD using in vitro and in vivo approaches. MethodsWe developed an in vitro cell culture disease model by using LAD-2 MC, HaCaT keratinocytes and RAW 264.7 macrophage cell lines. We challenged keratinocytes and macrophage cells with CST-14 treated MC supernatant in the presence and absence of GE1111 and measured the expression of tight junction protein claudin 1, inflammatory cytokines and macrophage phagocytosis activity through immunohistochemistry, western blotting, RT-qPCR and fluorescence imaging techniques. In addition to this, we developed a DFNB-induced AD model in mice and evaluated the protective effect and underlying mechanism of GE1111.Results and DiscussionOur in vitro findings demonstrated a potential therapeutic effect of GE1111, which inhibits the expression of TSLP, IL-13, MCP-1, TNF-a, and IL-1ß in MC and keratinocytes. In addition to this, GE1111 was able to preserve the expression of claudin 1 in keratinocytes and the phagocytotic activity of macrophage cells. The in vivo results demonstrated that GE1111 treatment significantly reduced phenotypic changes associated with AD (skin thickening, scaling, erythema and epidermal thickness). Furthermore, immunohistochemical analysis demonstrated that GE1111 treatment preserved the expression of the tight junction protein Involucrin and reduced the expression of the inflammatory mediator periostin in the mouse model of AD. These findings were supported by gene and protein expression analysis, where GE1111 treatment reduced the expression of TSLP, IL-13, and IL-1ß, as well as downstream signalling pathways of MRGPRX2 in AD skin lesions. In conclusion, our findings provide compelling in vitro and in vivo evidence supporting the contribution of MRGPRX2-MC interaction with keratinocytes and macrophages in the pathogenesis of AD.

Synergistic induction of blood–brain barrier properties

Blood-brain barrier (BBB) models derived from human stem cells are powerful tools to improve our understanding of cerebrovascular diseases and to facilitate drug development for the human brain. Yet providing stem cell-derived endothelial cells with the right signaling cues to acquire BBB characteristics while also retaining their vascular identity remains challenging. Here, we show that the simultaneous activation of cyclic AMP and Wnt/β-catenin signaling and inhibition of the TGF-β pathway in endothelial cells robustly induce BBB properties in vitro. To target this interaction, we present a small-molecule cocktail named cARLA, which synergistically enhances barrier tightness in a range of BBB models across species. Mechanistically, we reveal that the three pathways converge on Wnt/β-catenin signaling to mediate the effect of cARLA via the tight junction protein claudin-5. We demonstrate that cARLA shifts the gene expressional profile of human stem cell-derived endothelial cells toward the in vivo brain endothelial signature, with a higher glycocalyx density and efflux pump activity, lower rates of endocytosis, and a characteristic endothelial response to proinflammatory cytokines. Finally, we illustrate how cARLA can improve the predictive value of human BBB models regarding the brain penetration of drugs and targeted nanoparticles. Due to its synergistic effect, high reproducibility, and ease of use, cARLA has the potential to advance drug development for the human brain by improving BBB models across laboratories.

Poria cocos Attenuated DSS-Induced Ulcerative Colitis via NF-κB Signaling Pathway and Regulating Gut Microbiota.

Ulcerative colitis (UC), as a chronic inflammatory disease, presents a global public health threat. However, the mechanism of Poria cocos (PC) in treating UC remains unclear. Here, LC-MS/MS was carried out to identify the components of PC. The protective effect of PC against UC was evaluated by disease activity index (DAI), colon length and histological analysis in dextran sulfate sodium (DSS)-induced UC mice. ELISA, qPCR, and Western blot tests were conducted to assess the inflammatory state. Western blotting and immunohistochemistry techniques were employed to evaluate the expression of tight junction proteins. The sequencing of 16S rRNA was utilized for the analysis of gut microbiota regulation. The results showed that a total of fifty-two nutrients and active components were identified in PC. After treatment, PC significantly alleviated UC-associated symptoms including body weight loss, shortened colon, an increase in DAI score, histopathologic lesions. PC also reduced the levels of inflammatory cytokines TNF-α, IL-6, and IL-1β, as evidenced by the suppressed NF-κB pathway, restored the tight junction proteins ZO-1 and Claudin-1 in the colon, and promoted the diversity and abundance of beneficial gut microbiota. Collectively, these findings suggest that PC ameliorates colitis symptoms through the reduction in NF-κB signaling activation to mitigate inflammatory damage, thus repairing the intestinal barrier, and regulating the gut microbiota.

Effect of 125% and 135% arginine on the growth performance, intestinal health, and immune responses of broilers during necrotic enteritis challenge

The objective of this study was to evaluate the effects of 25% and 35% arginine supplementation in partially alleviating the effects of necrotic enteritis (NE) challenge on the production performance, intestinal integrity, and relative gene expression of tight junction proteins and inflammatory cytokines in broilers. Four hundred and eighty 1-day-old chicks were randomly allocated to the 4 treatments- Uninfected + Basal, NE + Basal, NE + Arg 125%, and NE + Arg 135%. NE was induced by inoculating 1 × 104Eimeria maxima sporulated oocysts on d 14 and 1 × 108 CFU/bird C. perfringens on d 19, 20, and 21 of age by oral gavage. The NE challenge significantly decreased body weight gain (BWG) (p < 0.05) and increased the feed conversion ratio (FCR) (p < 0.05). On d 21, the NE challenge also increased the jejunal lesion score (p < 0.05) and relative gene expression of IL-10 and decreased the expression of the tight junction proteins occludin (p < 0.05) and claudin-4 (p < 0.05). The 125% arginine diet significantly increased intestinal permeability (p < 0.05) and the relative gene expression of iNOS (p < 0.05) and IFN-γ (p < 0.05) on d 21 and the bile anti-C. perfringens IgA concentration by 39.74% (p < 0.05) on d 28. The 135% arginine diet significantly increased the feed intake during d 0 - 28 (p < 0.05) and 0 to 35 (p < 0.05) and increased the FCR on d 0 to 35 (p < 0.05). The 135% and 125% arginine diet increased the spleen CD8+: CD4+ T-cell ratio on d 28 (p < 0.05) and 35 (p < 0.05), respectively. The 135% arginine diet increased the CT CD8+:CD4+ T-cell ratio on d 35 (p < 0.05). In conclusion, the 125% and 135% arginine diets did not reverse the effect of the NE challenge on the growth performance. However, the 125% arginine diet significantly increased the cellular and humoral immune response to the challenge. Hence, the 125% arginine diet could be used with other feed additives to improve the immune response of the broilers during the NE challenge.

WITHDRAWN: Recombinant osteopontin stabilizes the blood brain barrier following subarachnoid hemorrhage in rats

Background and PurposeRecombinant osteopontin (rOPN) decreases neuronal cell death and brain edema and improves the neurological scores following subarachnoid hemorrhage (SAH) in rats. The molecular mechanisms of the preservation of blood-brain barrier of rOPN following SAH in rats were examined in this study. MethodsAdult rats were divided into 3 groups: sham, vehicle, and treatment groups. Each animal in the SAH group underwent a surgical procedure to induce SAH, and the brains was harvested at 24 hours for analysis. For the mechanism part of the study two additional groups were operated and treated with Fib-14 and Wortmannin additional to rOPN. rOPN was administered via the nasal route and neurological scores as well as brain water content were evaluated at 24 hours after SAH induction. The blood brain barrier (BBB) permeability was evaluated using Evans Blue dye extravasation. The expressions of tight junction proteins claudin-3, claudin-5, occludin and the phosphorylation of β-catenin were examined using Western blot analysis. ResultsrOPN improved neurological scores and reduced brain edema at 24 hours after SAH. The BBB preservation action of rOPN is mediated in part through stabilizing β-catenin and increasing expression of tight junction proteins, claudin-3, claudin-5, and occludin. rOPN is thought to exert its effects through FAK activated PI3K-Akt pathway. ConclusionSince BBB disruption is one of the major pathophysiology of EBI after SAH, rOPN may be a promising drug to maintain BBB integrity and functions in SAH treatment.

Delta like 4 regulates cerebrovascular development and endothelial integrity via DLL4-NOTCH-CLDN5 pathway and is vulnerable to neonatal hyperoxia.

The mechanisms governing brain vascularization during development remain poorly understood. A key regulator of developmental vascularization is delta like 4 (DLL4), a Notch ligand prominently expressed in endothelial cells (EC). Exposure to hyperoxia in premature infants can disrupt the development and functions of cerebral blood vessels and lead to long-term cognitive impairment. However, its role in cerebral vascular development and the impact of postnatal hyperoxia on DLL4 expression in mouse brain EC have not been explored. We determined the DLL4 expression pattern and its downstream signalling gene expression in brain EC using Dll4+/+ and Dll4+/LacZ mice. We also performed in vitro studies using human brain microvascular endothelial cells. Finally, we determined Dll4 and Cldn5 expression in mouse brain EC exposed to postnatal hyperoxia. DLL4 is expressed in various cell types, with EC being the predominant one in immature brains. Moreover, DLL4 deficiency leads to persistent abnormalities in brain microvasculature and increased vascular permeability both in vivo and in vitro. We have identified that DLL4 insufficiency compromises endothelial integrity through the NOTCH-NICD-RBPJ-CLDN5 pathway, resulting in the downregulation of the tight junction protein claudin 5 (CLDN5). Finally, exposure to neonatal hyperoxia reduces DLL4 and CLDN5 expression in developing mouse brain EC. We reveal that DLL4 is indispensable for brain vascular development and maintaining the blood-brain barrier's function and is repressed by neonatal hyperoxia. We speculate that reduced DLL4 signalling in brain EC may contribute to the impaired brain development observed in neonates exposed to hyperoxia. KEY POINTS: The role of delta like 4 (DLL4), a Notch ligand in vascular endothelial cells, in brain vascular development and functions remains unknown. We demonstrate that DLL4 is expressed at a high level during postnatal brain development in immature brains and DLL4 insufficiency leads to abnormal cerebral vasculature and increases vascular permeability both in vivo and in vitro. We identify that DLL4 regulates endothelial integrity through NOTCH-NICD-RBPJ-CLDN5 signalling. Dll4 and Cldn5 expression are decreased in mouse brain endothelial cells exposed to postnatal hyperoxia.

Therapeutic effect of Yinhuapinggan granules mediated through the intestinal flora in mice infected with the H1N1 influenza virus.

In this study, we examined the therapeutic effects of Yinhuapinggan granules (YHPGs) in influenza-infected mice. We also examined how YHPGs affect the composition of the intestinal flora and associated metabolites. We used the nasal drip method to administer the influenza A virus (IAV) H1N1 to ICR mice. Following successful model construction, the mice were injected with 0.9% sterile saline and low (5.5 g/kg), medium (11 g/kg), and high (22 g/kg) doses of YHPGs. The pathological changes in the lungs and intestines were evaluated by gavage for 5 consecutive days. Detection of sIgA, IL-6, TNF-α, INF-γ, and TGF-β cytokine levels in serum by enzyme-linked immunosorbent assay. Real-time fluorescence quantitative polymerase chain reaction and Western blot were used to measure the mRNA and protein expression of the tight junction proteins claudin-1, occludin, and zonula occludens-1 (ZO-1) in the colon. To assess the influence of YHPGs on the intestinal microbiota, feces were obtained from the mice for 16s rRNA sequencing, and short-chain fatty acids (SCFAs) were measured in the feces. By reducing the production of pro-inflammatory cytokines and increasing the relative expression of claudin-1, occludin, and ZO-1 in colon tissues, YHPGs had a protective effect in tissues from the lungs and colon. When YHPGs were administered to mice with IAV infection, the relative abundance of Lactobacillus, Coprobacillus, Akkermansia, Prevotella, Oscillospira, and Ruminococcus increased, whereas the relative abundance of Desulfovibrio decreased. The therapeutic mechanism of YHPGs against IAV infection in mice may be underpinned by modulation of the structural composition of colonic bacteria and regulation of SCFA production.

Colonic crypt stem cell functions are controlled by tight junction protein claudin-7 through Notch/Hippo signaling.

The tight junction protein claudin-7 is essential for tight junction function and intestinal homeostasis. Cldn7 deletion in mice leads to an inflammatory bowel disease-like phenotype exhibiting severe intestinal epithelial damage, weight loss, inflammation, mucosal ulcerations, and epithelial hyperplasia. Claudin-7 has also been shown to be involved in cancer metastasis and invasion. Here, we test our hypothesis that claudin-7 plays an important role in regulating colonic intestinal stem cell function. Conditional knockout of Cldn7 in the colon led to impaired epithelial cell differentiation, hyperproliferative epithelium, a decrease in active stem cells, and dramatically altered gene expression profiles. In 3D colonoid culture, claudin-7-deficient crypts were unable to survive and form spheroids, emphasizing the importance of claudin-7 in stem cell survival. Inhibition of the Hippo pathway or activation of Notch signaling partially rescued the defective stem cell behavior. Concurrent Notch activation and Hippo inhibition resulted in restored colonoid survival, growth, and differentiation to the level comparable to those of wild-type derived crypts. In this study, we highlight the essential role of claudin-7 in regulating Notch and Hippo signaling-dependent colonic stem cell functions, including survival, self-renewal, and differentiation. These new findings may shed light on potential avenues to explore for drug development in colorectal cancer.

Electroacupuncture can Modify Stress, Low-Grade Inflammation in the Duodenum, and Damage to the Intestinal Barrier in Rats with Functional Dyspepsia through the CRF Signaling Pathway

In the domain of functional gastrointestinal disorders, Functional Dyspepsia (FD) stands out due to its widespread occurrence internationally. Historically, electroacupuncture (EA) has been employed as a therapeutic modality for FD, demonstrating notable clinical efficacy. This research aimed to delve into the impact of EA on stress responses, minor duodenal inflammatory processes, and the integrity of the intestinal barrier within FD-affected rodent models while also elucidating the underlying mechanisms. Thirty-six male Wistar rats were evenly distributed into three cohorts: a normal, a modeled FD, and an EA treatment group. The FD condition in the rats, barring those in the normal, was induced through a series of multifactorial procedures. For the EA cohort, the rats received electroacupuncture at the acupoints RN12 (Zhongwan) and ST36 (Zusanli) for 20 minutes daily over a span of one week. The gastric residue rate (GRR), intestinal propulsion rate (IPR), and changes in emotional state were measured in each group of rats. Additionally, serum levels of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and corticosterone (CORT) were detected, and the duodenal inflammatory condition and intestinal mucosal barrier status were observed through staining and fluorescence. The expression levels of Claudin-1, Junctional Adhesion Molecule 1 (JAM-1), Corticotropin-Releasing Factor (CRF), and Corticotropin-Releasing Factor Receptor 1 (CRF-R1) were also detected. The study demonstrated that EA had a positive effect on body weight and food intake, GRR, and IPR in FD rats. Additionally, the EA group showed a decrease in serum levels of CRH, ACTH, and CORT, as well as a decrease in the number of duodenal mast cells and tryptase content. Furthermore, the expression of tight junction proteins Claudin-1 and JAM-1 was increased in the EA group compared to the model group. EA also reduced the levels of CRF and CRF-R1 in the hypothalamus and duodenum. EA has been shown to improve the stress state of FD rats, inhibit the activation of mast cells in the duodenum, and reduce low-grade inflammatory response and damage to the intestinal mucosal barrier. It is believed that EA achieves these effects by modulating the expression of CRF and its receptors in the brain-gut interaction pathway through the CRF signaling pathway. This provides a new approach to treating FD.

Neuroprotective effects of takinib on an experimental traumatic brain injury rat model via inhibition of transforming growth factor beta-activated kinase 1

Transforming growth factor β-activated kinase 1 (TAK1) plays a significant role in controlling several signaling pathways involved with regulating inflammation and apoptosis. As such, it represents an important potential target for developing treatments for traumatic brain injury (TBI). Takinib, a small molecule and selective TAK1 inhibitor, has potent anti-inflammatory activity and has shown promising activity in preclinical studies using rat models to evaluate the potential neuroprotective impact on TBI. The current study used a modified Feeney's weight-drop model to cause TBI in mature Sprague-Dawley male rats. At 30 min post-induction of TBI in the rats, they received an intracerebroventricular (ICV) injection of Takinib followed by assessment of their histopathology and behavior. The results of this study demonstrated how Takinib suppressed TBI progression in the rats by decreasing TAK1, p-TAK1, and nuclear p65 levels while upregulating IκB-α expression. Takinib was also shown to significantly inhibit the production of two pro-inflammatory factors, namely tumor necrosis factor-α and interleukin-1β. Furthermore, Takinib greatly upregulated the expression of tight junction proteins zonula occludens-1 and claudin-5, reducing cerebral edema. Additionally, Takinib effectively suppressed apoptosis via downregulation of cleaved caspase 3 and Bax and reduction of TUNEL-positive stained cell count. As a result, an enhancement of neuronal function and survival was observed post-TBI. These findings highlight the medicinal value of Takinib in the management of TBI and offer an experimental justification for further investigation of TAK1 as a potential pharmacological target.

Transient receptor potential vanilloid 4 channel inhibition attenuates lung ischemia-reperfusion injury in a porcine lung transplant model.

Transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel important in many physiological and pathophysiological processes, including pulmonary disease. Using a murine model, we previously demonstrated that TRPV4 mediates lung ischemia-reperfusion injury, the major cause of primary graft dysfunction after transplant. The current study tests the hypothesis that treatment with a TRPV4 inhibitor will attenuate lung ischemia-reperfusion injury in a clinically relevant porcine lung transplant model. A porcine left-lung transplant model was used. Animals were randomized to 2 treatment groups (n=5/group): vehicle or GSK2193874 (selective TRPV4 inhibitor). Donor lungs underwent 30minutes of warm ischemia and 24hours of cold preservation before left lung allotransplantation and 4hours of reperfusion. Vehicle or GSK2193874 (1mg/kg) was administered to the recipient as a systemic infusion after recipient lung explant. Lung function, injury, and inflammatory biomarkers were compared. After transplant, left lung oxygenation was significantly improved in the TRPV4 inhibitor group after 3 and 4hours of reperfusion. Lung histology scores and edema were significantly improved, and neutrophil infiltration was significantly reduced in the TRPV4 inhibitor group. TRPV4 inhibitor-treated recipients had significantly reduced expression of interleukin-8, high mobility group box 1, P-selectin, and tight junction proteins (occludin, claudin-5, and zonula occludens-1) in bronchoalveolar lavage fluid as well as reduced angiopoietin-2 in plasma, all indicative of preservation of endothelial barrier function. Treatment of lung transplant recipients with TRPV4 inhibitor significantly improves lung function and attenuates ischemia-reperfusion injury. Thus, selective TRPV4 inhibition may be a promising therapeutic strategy to prevent primary graft dysfunction after transplant.

Duck compound probiotics fermented diet alters the growth performance by shaping the gut morphology, microbiota and metabolism

Dietary absorption and digestion are influenced by the microbiota, morphology, and digestive enzymes of intestines, and fermentation is a popular and effective technique to enhance animal rearing growth performance. This study aims to explore the pivotal role of Muscovy duck probiotics fermented feedstuff (FF) in altering the growth performance by reshaping gut morphology, microorganisms and metabolism. The findings showed that FF considerably raised the levels of fatty acids (FA) and small peptides (7-19AA) in the diet. Further feeding trial data reveals that FF greatly increased the Muscovy duck average daily gain (ADG) but had no effect on their daily feed intake (DFI), and the FCR significantly dropped (P < 0.05). Additionally, it was evident that FF improved the integrity of the intestinal mucosa in Muscovy duck by increasing villus height, villus height-to-crypt depth ratio, and lowering crypt depth. Then, in comparison to the control group (NC), there was a significant increase in the gene expression of the mucosal tight junction proteins Occludin, Claudin-1, and Zo-1 in the intestine of Muscovy duck. Additionally, there was higher expression of the mucosal transport channels SGLT-1, PepT1, AQP2, AQP3, and AQP10 in the similarly colon site, jejunum, and duodenum. Furthermore, in AB-PAS/PAS-stained duodenum, jejunum, ileum, and similarly colon site, FF markedly increased relative mucus output and goblet cells while decreasing epithelial cell apoptosis. Following 16S sequencing data indicated that the intestinal microbiota was altered and the diversity and richness of gut microbes was greatly enhanced by FF. Particularly, the boost of core probiotics, such as Rothia of duodenum, Limosilactobacillus and Lentilactobacillus of jejunum, Lactococcus and Rothia of ileum, Ligilactobacillus and Entocuccus of similarly colon site, Gallibacterium of caecum. And reduced potentially pathogenic bacteria (Campylobacter, Prevotellaceae, Clostridia-vadinBB60, and Oscillospira). Nontargeted metabolomics assay for intestinal content confirmed an increased organic acids (oxidanesulfonic acid, cholic acid, gallic acid, coumaric acid, pipecollc acid, 13s-hydroxyoctadecadienoic acid) and glycosides metabolites (5-hydroxydantrolene, 3-hydroxyguanfacine glucuronide, acetylleucine, astragalin, xanthosine, taxiphylin, sinapine, denudatine, penylalanyl-tyrosine and phenylalanyl-valine). These findings demonstrated that FF, a viable option to improve Muscovy duck growth performance through reconstructed intestinal morphology, microorganisms, and metabolism, subsequently promoted the gut health and increased diet digestion and absorption. The study that is being presented offers scientific proof that FF might be a useful strategy for improving Muscovy duck growth performance.

Abstract 829: Phthalate exposure results in circadian rhythm-induced BBB dysfunction increasing the risk for breast cancer brain metastasis

Abstract Phthalates, classified as plasticizers, represent a group of chemicals pervasive in the general U.S. population, with notably higher levels in non-Hispanic Blacks compared to non-Hispanic Whites. These persistent organic pollutants (POPs) have been identified for their impact on the circadian rhythms of the brain and vascular system. Several studies indicate that phthalates can elevate neuroinflammation and reduce levels of the junctional protein ZO-1 in the hypothalamus, home to the master circadian clock known as the suprachiasmatic nucleus (SCN). The SCN regulates cellular and tissue circadian rhythms, including tight junction proteins essential for the blood-brain barrier's (BBB) main barrier function. Interestingly, experimental studies reveal that prolonged chronic circadian rhythm disruption (CRD) in mice leads to increased breast cancer metastasis. However, the effects of phthalates on CRD concerning brain cancer and metastasis remain poorly understood. Given their significant prevalence and biological impact, we hypothesize that phthalate exposure induces CRD through hypothalamic dysregulation, resulting in BBB dysfunction and an elevated risk of brain metastasis. Results. We developed an in vitro BBB model using endothelial cells and exposed them to an environmentally relevant mixture of five phthalates simulating chronic low-grade exposure. Analysis showed dysregulation of critical clock genes (Bmal1 and Clock), along with a substantial decrease in BBB tight junction proteins (claudin-5 and occludin) at the protein and mRNA levels. The tumor trans-endothelial migration assay using breast adenocarcinoma cells along with endothelial cells demonstrated an increased metastatic potential following phthalate exposure. Conclusion. These findings offer crucial insights into the molecular mechanisms underlying phthalate exposure, suggesting potential targets for future brain metastasis treatments. Additionally, they hold implications for the future regulation and management of phthalate usage and policy. This work was supported by the University of Miami U-LINK Resilience Challenge grant. Citation Format: Destiny Tiburcio, Sarah Adolphe, Ijeoma B. Akpu, Timea Teglas, Oandy Naranjo, Sophia H. George, Michal J. Toborek. Phthalate exposure results in circadian rhythm-induced BBB dysfunction increasing the risk for breast cancer brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 829.

Abstract 2457: Brain derived endothelial cells as a mediator of cGAS-STING driven anti-tumor efficacy in glioblastoma

Abstract The median survival time for newly diagnosed patients with glioblastoma (GBM) is 15 months, highlighting the need for improved therapies. Current treatment for newly diagnosed and recurrent GBM consists of tumor resection and chemoradiation therapy. The immunosuppressive tumor microenvironment (TME) is a central obstacle in the treatment of GBM. Lack of NK cell and CD8+ T cell infiltration prevents efficacy with immunotherapies like immune checkpoint blockade (ICB).One approach our lab is pursuing to enhance tumor infiltrating lymphocytes is through harnessing the anti-viral cGAS-STING pathway. Upon cGAS activation by cytosolic double stranded DNA, the TBK1 kinase is phosphorylated, initiating a subsequent type I interferon (IFN) response and the recruitment of immune cells. This pathway is commonly altered in many cancer types to evade immune activation. Our lab has demonstrated survival benefits with STING agonist treatment in immunocompetent GBM mouse models. We have also shown strong STING localization in the vasculature, implicating endothelial cells as a potential treatment target for anti-tumor efficacy. Here we investigated the potential role of tumor vasculature in mediating the effects of STING agonists in GBM therapy.We have shown robust cGAS-STING activation in brain endothelial cell lines through enhanced secretion of CXCL10, IFN-β, and RANTES upon STING agonist treatment in vitro. Western blotting also shows pathway activation in response to treatment through increased phospho-TBK1 levels. Activation was further potentiated by manganese.To investigate the effects of STING activation in brain endothelial cells in detail, we performed RNA sequencing. This showed 262 differentially expressed genes in response to pharmacologic cGAS-STING activation, with 183 of these being upregulated. The top gene ontology terms enriched include type I interferon signaling pathway, defense response to virus, and antigen processing and presentation of exogenous peptide antigen via MHC class I, TAP-independent. In addition, gene expression of tight junction protein Claudin 5 was also enhanced. We have also shown increased resistance in response to activation, through transendothelial electrical resistance (TEER) assays. Taken together, these results suggest that cGAS-STING activation in endothelial cells leads to tight junction remodeling in addition to immunomodulatory changes, implicating roles for endothelial cells in barrier function and immune cell interactions respectively. Current research in our lab focuses on elucidating the mechanisms behind these changes. Our goal is to identify beneficial endothelial cell changes which promote anti-tumor immunity in order to inform future treatment strategies. We are currently performing studies aimed at demonstrating that cGAS-STING activation in endothelial cells is critical for the efficacy of STING agonist treatment. Citation Format: Andrea Schmidt, Sandra Remson, Philippa Vaughn-Beaucaire, Jorge L. Jimenez-Macias, Praveen Srinivasan, Maximillian Pinho-Schwermann, Sean Lawler. Brain derived endothelial cells as a mediator of cGAS-STING driven anti-tumor efficacy in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2457.

Mulberry leaf polysaccharide improves cyclophosphamide-induced growth inhibition and intestinal damage in chicks by modulating intestinal flora, enhancing immune regulation and antioxidant capacity.

Polysaccharides are generally considered to have immune enhancing functions, and mulberry leaf polysaccharide is the main active substance in mulberry leaves, while there are few studies on whether mulberry leaf polysaccharide (MLP) has an effect on immunosuppression and intestinal damage caused by cyclophosphamide (CTX), we investigated whether MLP has an ameliorative effect on intestinal damage caused by CTX. A total of 210 1-day-old Mahuang cocks were selected for this experiment. Were equally divided into six groups and used to evaluate the immune effect of MLP. Our results showed that MLP significantly enhanced the growth performance of chicks and significantly elevated the secretion of cytokines (IL-1β, IL-10, IL-6, TNF-α, and IFN-γ), immunoglobulins and antioxidant enzymes in the serum of immunosuppressed chicks. It attenuated jejunal damage and elevated the expression of jejunal tight junction proteins Claudin1, Zo-1 and MUC2, which protected intestinal health. MLP activated TLR4-MyD88-NF-κB pathway and enhanced the expression of TLR4, MyD88 and NF-κB, which served to protect the intestine. 16S rDNA gene high-throughput sequencing showed that MLP increased species richness, restored CTX-induced gut microbiome imbalance, and enhanced the abundance of probiotic bacteria in the gut. MLP improves cyclophosphamide-induced growth inhibition and intestinal damage in chicks by modulating intestinal flora and enhancing immune regulation and antioxidant capacity. In conclusion, this study provides a scientific basis for MLP as an immune enhancer to regulate chick intestinal flora and protect chick intestinal mucosal damage.

Rhodiola crenulata alleviates hypobaric hypoxia-induced brain injury by maintaining BBB integrity and balancing energy metabolism dysfunction

Background/Purpose: Rhodiola crenulata (Hook. f. et Thoms.) H. Ohba (R. crenulate), a famous and characteristic Tibetan medicine, has been demonstrated to exert an outstanding brain protection role in the treatment of high-altitude hypoxia disease. However, the metabolic effects of R. crenulate on high-altitude hypoxic brain injury (HHBI) are still incompletely understood. Herein, the anti-hypoxic effect and associated mechanisms of R. crenulate were explored through both in vivo and in vitro experiments. Study design/MethodsThe mice model of HHBI was established using an animal hypobaric and hypoxic chamber. R. crenulate extract (RCE, 0.5, 1.0 and 2.0 g/kg) and salidroside (Sal, 25, 50 and 100 mg/kg) was given by gavage for 7 days. Pathological changes and neuronal apoptosis of mice hippocampus and cortex were evaluated using H&E and TUNEL staining, respectively. The effects of RCE and Sal on the permeability of blood brain barrier (BBB) were detected by Evans blue staining and NIR-II fluorescence imaging. Meanwhile, the ultrastructural BBB and cerebrovascular damages were observed using a transmission electron microscope (TEM). The levels of tight junction proteins Claudin-1, ZO-1 and occludin were detected by immunofluorescence. Additionally, the metabolites in mice serum and brain were determined using UHPLC-MS and MALDI-MSI analysis. The cell viability of Sal on hypoxic HT22 cells induced by CoCl2 was investigated by cell counting kit-8. The contents of LDH, MDA, SOD, GSH-PX and SDH were detected by using commercial biochemical kits. Meanwhile, intracellular ROS, Ca2+ and mitochondrial membrane potential were determined by corresponding specific labeled probes. The intracellular metabolites of HT22 cells were performed by the targeted metabolomics analysis of the Q300 kit. The cell apoptosis and necrosis were examined by YO-PRO-1/PI, Annexin V/PI and TUNEL staining. In addition, mitochondrial morphology was tested by Mito-tracker red with confocal microscopy and TEM. Real-time ATP production, oxygen consumption rate, and proton efflux rate were measured using a Seahorse analyzer. Subsequently, MCU, OPA1, p-Drp1ser616, p-AMPKα, p-AMPKβ and Sirt1 were determined by immunofluorescent and western blot analyses. ResultsThe results demonstrated that R. crenulate and Sal exert anti-hypoxic brain protection from inhibiting neuronal apoptosis, maintaining BBB integrity, increasing tight junction protein Claudin-1, ZO-1 and occludin and improving mitochondrial morphology and function. Mechanistically, R. crenulate and Sal alleviated HHBI by enhancing the tricarboxylic acid cycle to meet the demand of energy of brain. Additionally, experiments in vitro confirmed that Sal could ameliorate the apoptosis of HT22 cells, improve mitochondrial morphology and energy metabolism by enhancing mitochondrial respiration and glycolysis. Meanwhile, Sal-mediated MCU inhibited the activation of Drp1 and enhanced the expression of OPA1 to maintain mitochondrial homeostasis, as well as activation of AMPK and Sirt1 to enhance ATP production. ConclusionCollectively, the findings suggested that RCE and Sal may afford a protective intervention in HHBI through maintaining BBB integrity and improving energy metabolism via balancing MCU-mediated mitochondrial homeostasis by activating the AMPK/Sirt1 signaling pathway.

Comparative Characterization of Human Meibomian Glands, Free Sebaceous Glands, and Hair-Associated Sebaceous Glands Based on Biomarkers, Analysis of Secretion Composition, and Gland Morphology.

Meibomian gland dysfunction (MGD) is one of the main causes of dry eye disease. To better understand the physiological functions of human meibomian glands (MGs), the present study compared MGs with free sebaceous glands (SGs) and hair-associated SGs of humans using morphological, immunohistochemical, and liquid chromatography-mass spectrometry (LCMS)-based lipidomic approaches. Eyelids with MGs, nostrils, lips, and external auditory canals with free SGs, and scalp with hair-associated SGs of body donors were probed with antibodies against cytokeratins (CK) 1, 8, 10, and 14, stem cell markers keratin 15 and N-cadherin, cell-cell contact markers desmoglein 1 (Dsg1), desmocollin 3 (Dsc3), desmoplakin (Dp), plakoglobin (Pg), and E-cadherin, and the tight junction protein claudin 5. In addition, Oil Red O staining (ORO) was performed in cryosections. Secretions of MGs as well as of SGs of nostrils, external auditory canals, and scalps were collected from healthy volunteers, analyzed by LCMS, and the data were processed using various multivariate statistical analysis approaches. Serial sections of MGs, free SGs, and hair-associated SGs were 3D reconstructed and compared. CK1 was expressed differently in hair-associated SGs than in MGs and other free SGs. The expression levels of CK8, CK10, and CK14 in MGs were different from those in hair-associated SGs and other free SGs. KRT15 was expressed differently in hair-associated SGs, whereas N-cadherin was expressed equally in all types of glands. The cell-cell contact markers Dsg1, Dp, Dsc3, Pg, and E-cadherin revealed no differences. ORO staining showed that lipids in MGs were more highly dispersed and had larger lipid droplets than lipids in other free SGs. Hair-associated SGs had a smaller number of lipid droplets. LCMS revealed that the lipid composition of meibum was distinctively different from that of the sebum of the nostrils, external auditory canals, and scalp. The 3D reconstructions of the different glands revealed different morphologies of the SGs compared with MGs which are by far the largest type of glands. In humans, MGs differ in their morphology and secretory composition and show major differences from free and hair-associated SGs. The composition of meibum differs significantly from that of sebum from free SGs and from hair-associated SGs. Therefore, the MG can be considered as a highly specialized type of holocrine gland that exhibits all the histological characteristics of SGs, but is significantly different from them in terms of morphology and lipid composition.

Cerebral endothelial cells mediated enhancement of brain pericyte number and migration in oxygen-glucose deprivation involves the HIF-1α/PDGF-β signaling

The present study focused on whether hypoxia-inducible factor-1alpha (HIF-1α) and platelet-derived factor-beta (PDGF-β) are involved in the crosstalk between brain microvascular endothelial cells (BMECs) and brain vascular pericytes (BVPs) under ischaemic-hypoxic conditions. Mono-cultures or co-cultures of BVPs and BMECs were made for the construction of the blood–brain barrier (BBB) model in vitro and then exposed to control and oxygen-glucose deprivation (OGD) conditions. BBB injury was determined by assessing the ability, apoptosis, and migration of BVPs and the transendothelial electrical resistance and horseradish peroxidase permeation of BMECs. Relative mRNA and protein levels of HIF-1α and PDGF-β, as well as tight junction proteins ZO-1 and claudin-5 were analyzed by western blotting, reverse transcription quantitative PCR, and/or immunofluorescence staining. Dual-luciferase reporter assays assessed the relationship between PDGF-β and HIF-1α. Co-culturing with BMECs alleviated OGD-induced reduction in BVP viability, elevation in BVP apoptosis, and repression in BVP migration. Co-culturing with BVPs protected against OGD-induced impairment on BMEC permeability. OGD-induced HIF-1α upregulation enhanced PDGF-β expression in mono-cultured BMECs and co-cultured BMECs with BVPs. Knockdown of HIF-1α impaired the effect of BMECs on BVPs under OGD conditions, and PDGFR-β silencing in BVPs blocked the crosstalk between BMECs and BVPs under OGD conditions. The crosstalk between BMECs and BVPs was implicated in OGD-induced BBB injury through the HIF-1α/PDGF-β signaling.

D-beta-hydroxybutyrate up-regulates Claudin-1 and alleviates the intestinal hyperpermeability in lipopolysaccharide-treated mice

The hyperpermeability of intestinal epithelium is a key contributor to the occurrence and development of systemic inflammation. Although D-beta-hydroxybutyrate (BHB) exhibits various protective effects, whether it affects the permeability of intestinal epithelium in systemic inflammation has not been clarified. In this study, we investigated the effects of BHB on the intestinal epithelial permeability, the epithelial marker E-cadherin and the tight junction protein Claudin-1 in colon in the lipopolysaccharide (LPS)-induced systemic inflammation mouse model. Intraperitoneal injection of LPS was used to induce systemic inflammation and BHB was given by oral administration. The permeability of intestinal epithelium, the morphological changes of colonic epithelium, the distribution and generation of colon E-cadherin, and the Claudin-1 generation and its epithelial distribution in colon were detected. The results confirmed the intestinal epithelial hyperpermeability and inflammatory changes in colonic epithelium, with disturbed E-cadherin distribution in LPS-treated mice. Besides, colon Claudin-1 generation was decreased and its epithelial distribution in colon was weakened in LPS-treated mice. However, BHB treatments alleviated the LPS-induced hyperpermeability of intestinal epithelium, attenuated the colonic epithelial morphological changes and promoted orderly distribution of E-cadherin in colon. Furthermore, BHB up-regulated colon Claudin-1 generation and promoted its colonic epithelial distribution and content in LPS-treated mice. In conclusion, BHB may alleviate the hyperpermeability of intestinal epithelium via up-regulation of Claudin-1 in colon in LPS-treated mice.