Densovirus crosses the insect midgut by transcytosis and disturbs the epithelial barrier function.
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ABSTRACT:
SUBMITTER: Wang Y
PROVIDER: S-EPMC3807927 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Densoviruses are insect parvoviruses that are orally infectious for Lepidoptera. To assess the mechanisms underlying their specificity and their virulence, we investigated the role of eight candidate residues in the densovirus capsid. We showed that the substitutions of four amino acids were associated with decreased virulence due to a decreased ability to cross the host midgut epithelium, without an effect on viral replication in other tissues.
| S-EPMC3347284 | biostudies-literature
Project description:Introduction Disruption of the epithelial barrier can induce eosinophilic esophagitis (EoE), a TH2-mediated food- and aeroallergen associated chronic inflammatory disease 1, 2. The expression of IL-20 subfamily cytokines, IL-19, IL-20 and IL-24, is increased in TH2-mediated diseases, yet their function in EoE is unknown. Methods Combining RNA-sequencing (RNA-seq) and proteome analysis, we have examined the effects of the IL-20 subfamily on esophageal epithelial cells using patient-derived organoids and an experimental EoE mouse model. Results When stimulated with IL-20 subfamily cytokines patient-derived esophageal organoids showed decreased expression of Filaggrin (FLG) and Filaggrin 2 (FLG2) responsible for epithelial cornification. In agreement, EoE patients with active inflammation showed elevated IL-20 subfamily cytokines and decreased FLG and FLG2 expression. Topical corticosteroid treatment in EoE patients restored filaggrin expression, while reducing IL-20 subfamily cytokines. Abolishment of IL-20 subfamily signalling in Il20R2-/- animals attenuated experimental EoE in an OVA-induced mouse model. In the esophageal keratinocyte cell line, KYSE-180, we identified IL-20 subfamily-induced STAT3 and MAPK (ERK1/2) pathway activation. However, Stat3fl/flKrt5cre mice with an epithelium specific deletion of Stat3 developed exacerbated experimental EoE with a pronounced decrease of Flg2. In line, combined stimulation of patient-derived esophageal organoids with IL-20 subfamily cytokines and pharmacological inhibition of STAT3 resulted in aggravated decrease of FLG and FLG2. In addition, pharmacological STAT3 inhibition resulted in reduced transepithelial electrical resistance (TEER) and increased macromolecular flux in patient-derived air liquid interface (ALI) cultures. Whereas, inhibition of the MAPK (ERK1/2) pathway hampered IL-20 subfamily induced TEER reduction and paracellular flux increment. Finally, MAPK (ERK1/2) inhibitor treatment reduced infiltrating CD45+ immune cells in the esophagus and alleviated experimental EoE in mice. Conclusion We discovered a novel regulatory function of the IL-20 subfamily for epithelial barrier integrity. Aberrant IL-20 subfamily signaling disturbs the epithelial barrier function, while abrogation of IL-20 subfamily and ERK1/2 signaling restores epithelial integrity and attenuates experimental EoE. Therefore, we propose that targeting the IL-20 subfamily pathway could present a novel therapeutic strategy for EoE treatment.
2023-05-10 | PXD031509 | Pride
Project description:As an optically transparent model organism with an endothelial blood-brain barrier (BBB), zebrafish offer a powerful tool to study the vertebrate BBB. However, the precise developmental profile of functional zebrafish BBB acquisition and the subcellular and molecular mechanisms governing the zebrafish BBB remain poorly characterized. Here, we capture the dynamics of developmental BBB leakage using live imaging, revealing a combination of steady accumulation in the parenchyma and sporadic bursts of tracer leakage. Electron microscopy studies further reveal high levels of transcytosis in brain endothelium early in development that are suppressed later. The timing of this suppression of transcytosis coincides with the establishment of BBB function. Finally, we demonstrate a key mammalian BBB regulator Mfsd2a, which inhibits transcytosis, plays a conserved role in zebrafish, as mfsd2aa mutants display increased BBB permeability due to increased transcytosis. Our findings indicate a conserved developmental program of barrier acquisition between zebrafish and mice.
| S-EPMC6726461 | biostudies-literature
Project description:Removal of particulate materials that would otherwise cumulate within the airspace and hinder the gas exchange is one of the central processes of maintaining lung homeostasis. While the importance of the particle uptake by alveolar macrophages and their expulsion via the airways mucociliary escalator is well established, very little is known about the alternative route for removing the particles via direct crossing the lung epithelium for transfer into the pulmonary lymph and bloodstream. This study dissected sequential mechanisms involved in nanoparticle transcytosis through the alveolar epithelial cell layer. By a combination of live cell, super resolution, and electron microscopy and RNA interference study, we have dissected temporal steps of nanoparticle transcytosis through alveolar epithelium. Our study revealed that caveolin is essential for the firm adhesion of the silica nanoparticle agglomerates to the apical membrane and their subsequent rapid internalization with the help of macropinocytic elements C-terminal-binding protein1 and Rabankyrin-5 but not dynamin. Actin, but not microtubules, played a major role in nanoparticle uptake and subsequent transportation. The compartments with nanoparticles were tethered to trans-Golgi network to be jointly transported along actin stress fibers across the cytoplasm, employing a myosin-dependent mechanism. The trans-Golgi nanoparticle transport machinery was positive to Rab6A, a marker linked to vesicle exocytosis. Exocytosis was primarily occurring at the basolateral plane of the alveolar epithelial cells. The high-proficiency novel caveolin and Rabankyrin-5 associated uptake and transcellular transport of nanoparticles across the AEC barrier supports its importance in clearance of amorphous silica and other types of non-inflammatory nanoparticles that are rapidly removed from the lungs following their inhalation.
| S-EPMC9178038 | biostudies-literature
Project description:Insect pests negatively affect crop quality and yield; identifying new methods to protect crops against insects therefore has important agricultural applications. Our analysis of transgenic Arabidopsis thaliana plants showed that overexpression of pentacyclic triterpene synthase 1, encoding the key biosynthetic enzyme for the natural plant product (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), led to a significant resistance against a major insect pest, Plutella xylostella. DMNT treatment severely damaged the peritrophic matrix (PM), a physical barrier isolating food and pathogens from the midgut wall cells. DMNT repressed the expression of PxMucin in midgut cells, and knocking down PxMucin resulted in PM rupture and P. xylostella death. A 16S RNA survey revealed that DMNT significantly disrupted midgut microbiota populations and that midgut microbes were essential for DMNT-induced killing. Therefore, we propose that the midgut microbiota assists DMNT in killing P. xylostella. These findings may provide a novel approach for plant protection against P. xylostella.
| S-EPMC7924945 | biostudies-literature
Project description:BackgroundAlteration of commensal bacterial composition is associated with many inflammatory diseases. However, few studies have pinpointed the specific bacterial genes that may suppress host immune responses against microbes and maintain homeostasis in the host intestine.MethodsHigh-throughput screening was performed in Caenorhabditis elegans with a single gene knockout ut screening was performed in Caenorhabditis elegans with a single gene knockout Escherichia coli (E. coli) library and identified the immune suppression gene blc. The coding sequences of blc among different kinds of E. coli strains were aligned to identify the single nucleotide polymorphisms (SNPs). Physiological and biochemical experiments were performed in C. elegans and mice to explore the function of the blc variant.FindingsBy screening 3983 E. coli mutants, we discovered that 9 bacterial genes, when deleted, activate innate immunity in the host C. elegans. Among these 9 genes, the gene encoding blc showed a distinctive SNP in many clinically pathogenic bacteria. We found that bacteria with this SNP, which converts Blc G84 to Blc E84, are highly enriched in the faeces of patients with inflammatory bowel disease (IBD). Exposure to BlcE84-encoding bacteria resulted in epithelial barrier disruption and immune activation in both worms and mice. Detailed analysis indicated that infection with BlcE84-encoding bacteria causes a significant decrease in LPE levels in the intestine and subsequently disrupts gut epithelial integrity in mice. Consistently, the levels of LPE in patients with IBD are significantly lower than those in healthy people. Finally, supplementation with LPE, which activates LPA1/PLCβ/PKC signaling, reversed the defects induced by BlcE84-encoding bacteria.InterpretationOur results identified a novel bacterial gene, blc, in E. coli that regulates host gut integrity and immunity. FUND: The Ministry of Science and Technology of China; the National Natural Science Foundation of China; and the Natural Science Foundation of Jiangsu Province.
| S-EPMC7026729 | biostudies-literature
Project description:The intestinal epithelial barrier plays an essential role in maintaining host homeostasis. The barrier regulates nutrient absorption as well as prevents the invasion of pathogenic bacteria in the host. It is composed of epithelial cells, tight junctions, and a mucus layer. Several factors, such as cytokines, diet, and diseases, can affect this barrier. These factors have been shown to increase intestinal permeability, inflammation, and translocation of pathogenic bacteria. In addition, dysregulation of the epithelial barrier can result in inflammatory diseases such as inflammatory bowel disease. Our lab and others have also shown that barrier disruption can have systemic effects including bone loss. In this chapter, we will discuss the current literature to understand the link between intestinal barrier and bone. We will discuss how inflammation, aging, dysbiosis, and metabolic diseases can affect intestinal barrier-bone link. In addition, we will highlight the current suggested mechanism between intestinal barrier and bone.
| S-EPMC5742533 | biostudies-literature
Project description:PLEKHA7 is a recently identified protein of the epithelial zonula adhaerens (ZA), and is part of a protein complex that stabilizes the ZA, by linking it to microtubules. Since the ZA is important in the assembly and disassembly of tight junctions (TJ), we asked whether PLEKHA7 is involved in modulating epithelial TJ barrier function. We generated clonal MDCK cell lines in which one of four different constructs of PLEKHA7 was inducibly expressed. All constructs were localized at junctions, but constructs lacking the C-terminal region were also distributed diffusely in the cytoplasm. Inducible expression of PLEKHA7 constructs did not affect the expression and localization of TJ proteins, the steady-state value of transepithelial resistance (TER), the development of TER during the calcium switch, and the flux of large molecules across confluent monolayers. In contrast, expression of three out of four constructs resulted both in enhanced recruitment of E-cadherin and associated proteins at the apical ZA and at lateral puncta adherentia (PA), a decreased TER at 18 h after assembly at normal calcium, and an attenuation in the fall in TER after extracellular calcium removal. This latter effect was inhibited when cells were treated with nocodazole. Immunoprecipitation analysis showed that PLEKHA7 forms a complex with the cytoplasmic TJ proteins ZO-1 and cingulin, and this association does not depend on the integrity of microtubules. These results suggest that PLEKHA7 modulates the dynamics of assembly and disassembly of the TJ barrier, through E-cadherin protein complex- and microtubule-dependent mechanisms.
| S-EPMC4022608 | biostudies-literature
Project description:PurposeThe purpose of this study was to determine whether 25-hydroxyvitamin D(3) (25(OH)D(3)) and/or its active metabolite, 1α,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), can enhance corneal epithelial barrier function. The authors also determined if corneas contain mRNA for the vitamin D receptor (VDR) and 1α-hydroxylase, the enzyme required to convert 25(OH)D(3) to 1,25(OH)(2)D(3), and measured vitamin D metabolite concentrations in aqueous and vitreous humor.MethodsRT-PCR was used to examine mouse, rabbit, and human corneal epithelial VDR and 1α-hydroxylase mRNA. Vitamin D metabolites were measured using a selective vitamin D derivatizing agent and mass spectroscopy. Barrier function experiments were performed by measuring inulin permeability (IP) and/or transepithelial resistance (TER) in control, 25(OH)D(3)-, and 1,25(OH)(2)D(3)-treated human and rabbit corneal epithelial monolayers cultured on permeable inserts. Ca(2+) was removed, then reintroduced to the culture medium while IP and TER readings were taken. Occludin levels were examined using Western blotting.ResultsAll corneal samples were positive for both VDR and 1α-hydroxylase mRNA. All vitamin D metabolites except for unhydroxylated vitamin D(3) were detected in aqueous and vitreous humor. Epithelial cells showed increased TER, decreased IP, and increased occludin levels when cultured with 25(OH)D(3) and 1,25(OH)(2)D(3).ConclusionsWe conclude that corneas contain mRNA for VDR and 1α-hydroxylase as well as significant vitamin D concentrations. 25(OH)D(3) and its active metabolite 1,25(OH)(2)D(3), both enhance corneal epithelial barrier function.
| S-EPMC3183972 | biostudies-literature
Project description:Epithelial cell function is modulated by mechanical forces imparted by the extracellular environment. The transmission of forces onto the cytoskeleton by modalities such as mechanical stress and matrix stiffness is necessary to address by the development of new experimental models that permit finely tuned cell mechanical challenges. Herein, we developed an epithelial tissue culture model, named the 3D Oral Epi-mucosa platform, to investigate the role mechanical cues in the epithelial barrier. In this platform, low-level mechanical stress (0.1 kPa) is applied to oral keratinocytes, which lie on 3D fibrous collagen (Col) gels whose stiffness is modulated by different concentrations or the addition of other factors such as fibronectin (FN). Our results show that cells lying on intermediate Col (3 mg/mL; stiffness = 30 Pa) demonstrated lower epithelial leakiness compared with soft Col (1.5 mg/mL; stiffness = 10 Pa) and stiff Col (6 mg/mL; stiffness = 120 Pa) gels, indicating that stiffness modulates barrier function. In addition, the presence of FN reversed the barrier integrity by inhibiting the interepithelial interaction via E-cadherin and Zonula occludens-1. Overall, the 3D Oral Epi-mucosa platform, as a new in vitro system, will be utilized to identify new mechanisms and develop future targets involved in mucosal diseases.
| S-EPMC10215350 | biostudies-literature