scholarly journals A prior exposure to Serratia marcescens or xenobiotics primes Drosophila enterocytes against a recurring cytoplasmic purge

2021 ◽  
Author(s):  
Simone Terreri ◽  
Bechara Sina-Rahme ◽  
Ines S Pais ◽  
Catherine Socha ◽  
Matthieu Lestradet ◽  
...  

The cytoplasmic extrusion of enterocytes is a fast response to an exposure to pore-forming toxin (PFT)-producing bacteria whereby their apical cytoplasm is extruded into the intestinal lumen. As a result of this purge, the intestinal epithelium becomes thin prior to a subsequent recovery. We report here that the ingestion of ethanol or caffeine induces a similar response, which suggests that a common purging process is triggered by bacterial toxins and abiotic toxicants. We also delineate an additional mechanism that is initiated by these stimuli that we refer to as priming. The initial exposure of the intestinal epithelium to either PFT or xenobiotics protects enterocytes against a further round of purging upon a second bacterial infection. Priming prevents the epithelium from being persistently thin in the context of chronic intestinal infections. We have identified the upper part of the p38b MAPK pathway as well as the homeobox-containing transcription factors E5/EMS as being required for priming and not for the regrowth of enterocytes after the cytoplasmic purge. Unexpectedly, the priming process appears to function cell-nonautonomously. Our findings suggest that the cytoplasmic purge extrusion has been selected because it constitutes a fast reaction to accidental exposure to bacterial toxins or toxicants.

Author(s):  
В.А. Зарубина ◽  
О.В. Самодова ◽  
Н.В. Соловьева ◽  
Е.В. Тихонова ◽  
Н.Л. Рогушина

Острые кишечные инфекции остаются одной самых актуальных проблем педиатрии в связи с высоким уровнем заболеваемости, развитием тяжелых форм и летальности, особенно у детей первых пяти лет жизни. В большинстве случаев тяжесть заболевания обусловлена развитием эксикоза, в основе которого лежат потери электролитов и жидкости в следствии эметического и диарейного синдромов. Однако существуют различия в механизмах формирования дегидратации в зависимости от вида инфекционного агента. Так при дегидратации, вызванной вирусами, в основе лежит механизм нарушения абсорбции, причиной которого являются дистрофические изменения в энтероцитах и уменьшение количества клеток, способных адсорбировать жидкость из кишечника. Повышение осмотического давления в процессе нарушенной ферментации нерасщепленных дисахаридов приводит к перемещению воды в просвет кишечника и объясняет появление осмотической диареи и, как следствие, тяжелой дегидратации при отсутствии своевременной коррекции данного патологического состояния. При внедрении бактериальных кишечных патогенов, происходит воздействие различных энтеротоксинов на мембранные комплексы. В частности, стимулируется выработка медиаторов воспаления, повышается уровень внутриклеточного циклического аденозинмонофосфата или циклического гуанозинмонофосфата или происходит нарушение проницаемости слизистой оболочки кишечника под влиянием специфических белков инвазивных патогенов и в целом изменение активности нормального процесса обмена ионов. В статье так же рассмотрены альтернативные механизмы развития диареи при участии энтероэндокринно-нейронных рефлексов, а также описаны типы дегидратации с детализацией водно-электролитных нарушений и современные подходы к регидратационной терапии. Знание и понимание особенностей патогенеза, диагностики типа дегидратации необходимо практикующему врачу для выбора тактики патогенетической терапии острых кишечных инфекций у детей. Acute intestinal infections are one of the most urgent challenges in pediatrics due to a high morbidity, development of severe forms and mortality, especially in children under five years. In most cases, severity of the disease is due to development of exicosis induced by loss of electrolytes and fluids as a result of emetic and diarrheal syndromes. However, the mechanisms of dehydration differ depending on the type of infectious agent. Thus, dehydration caused by viruses is due to the mechanism of absorption disorders induced by dystrophic changes in enterocytes and reduced number of cells that could absorb fluid from the intestine. The increase in osmotic pressure under disturbed fermentation of unsplit disaccharides results in translocation of water into the intestinal lumen, which explains the development of osmotic diarrhea and ensuing severe dehydration in the absence of timely correction of this pathological condition. After invasion of bacterial intestinal pathogens, various enterotoxins impact membrane complexes. Specifically, production of inflammatory mediators is stimulated, levels of intracellular cyclic adenosine monophosphate or cyclic guanosine monophosphate increase, or specific proteins of invading pathogens affect the permeability of intestinal mucosa and, eventually, change the activity of normal ion exchange process. The article also addresses alternative mechanisms of diarrhea involving enteroendocrine-neural reflexes and focuses on types of dehydration with a detailed description of water-electrolyte disorders and modern approaches to rehydration therapy. Knowledge and understanding of the pathogenetic and diagnostic features specific for a dehydration type are necessary for practitioners to choose the tactics for pathogenetic therapy of children’s acute intestinal infections. The aim of this review was to summarize modern aspects of the pathogenesis of exicosis syndrome in acute intestinal infections in young children.


2011 ◽  
Vol 208 (11) ◽  
pp. 2263-2277 ◽  
Author(s):  
Georgios Nikitas ◽  
Chantal Deschamps ◽  
Olivier Disson ◽  
Théodora Niault ◽  
Pascale Cossart ◽  
...  

Listeria monocytogenes (Lm) is a foodborne pathogen that crosses the intestinal barrier upon interaction between its surface protein InlA and its species-specific host receptor E-cadherin (Ecad). Ecad, the key constituent of adherens junctions, is typically situated below tight junctions and therefore considered inaccessible from the intestinal lumen. In this study, we investigated how Lm specifically targets its receptor on intestinal villi and crosses the intestinal epithelium to disseminate systemically. We demonstrate that Ecad is luminally accessible around mucus-expelling goblet cells (GCs), around extruding enterocytes at the tip and lateral sides of villi, and in villus epithelial folds. We show that upon preferential adherence to accessible Ecad on GCs, Lm is internalized, rapidly transcytosed across the intestinal epithelium, and released in the lamina propria by exocytosis from where it disseminates systemically. Together, these results show that Lm exploits intrinsic tissue heterogeneity to access its receptor and reveal transcytosis as a novel and unanticipated pathway that is hijacked by Lm to breach the intestinal epithelium and cause systemic infection.


2017 ◽  
Vol 398 (10) ◽  
pp. 1069-1085 ◽  
Author(s):  
Elena Kudryashova ◽  
Stephanie M. Seveau ◽  
Dmitri S. Kudryashov

Abstract Defensins, as a prominent family of antimicrobial peptides (AMP), are major effectors of the innate immunity with a broad range of immune modulatory and antimicrobial activities. In particular, defensins are the only recognized fast-response molecules that can neutralize a broad range of bacterial toxins, many of which are among the deadliest compounds on the planet. For a decade, the mystery of how a small and structurally conserved group of peptides can neutralize a heterogeneous group of toxins with little to no sequential and structural similarity remained unresolved. Recently, it was found that defensins recognize and target structural plasticity/thermodynamic instability, fundamental physicochemical properties that unite many bacterial toxins and distinguish them from the majority of host proteins. Binding of human defensins promotes local unfolding of the affected toxins, destabilizes their secondary and tertiary structures, increases susceptibility to proteolysis, and leads to their precipitation. While the details of toxin destabilization by defensins remain obscure, here we briefly review properties and activities of bacterial toxins known to be affected by or resilient to defensins, and discuss how recognized features of defensins correlate with the observed inactivation.


1973 ◽  
Vol 30 (3) ◽  
pp. 369-377 ◽  
Author(s):  
John C. Davis

Sublethal effects of aerated neutralized, filtered, full bleach kraft mill effluent (BKME) on circulation and respiration of Pacific salmon were examined. Ventilatory water flow, oxygen uptake, cough frequency, and buccal pressure increased in a group of 19 sockeye salmon, Oncorhynchus nerka, 207–321 g, at 10.5 ± 0.5 C, upon initial exposure to sublethal BKME concentrations. The threshold concentration for these responses appreared to be around 20% of the 4 day LC50 (static bioassay).Following overnight exposure to BKME, ventilatory volume, oxygen uptake rate, cough frequency, and oxygen utilization tended to approach pre-exposure levels, particularly at the higher sublethal contractions. Changing effluent toxicity, acclimation phenomena, or physiological adjustment are discussed as possible explanations for these results.Measures of arterial oxygen tension in sockeye salmon indicated that arterial tension declines rapidly and remains depressed following up to 24 hr exposure to BKME (33–47% of 4 day LC50). On the average this decline represented a 20% decrease in oxygen saturation of the blood. Decreased arterial PO2 may be due to mucous production at the gills and resulting gas diffusion problems, as well as abnormalities in ventilation. Reduction in scope for activity might result from impaired oxygen uptake at the gills. A similar response was observed in rainbow trout, Salmo gairdneri.


1998 ◽  
Vol 72 (12) ◽  
pp. 9795-9805 ◽  
Author(s):  
Christine L. Halbert ◽  
Thomas A. Standaert ◽  
Christopher B. Wilson ◽  
A. Dusty Miller

ABSTRACT The airway is an important target for gene transfer to treat cystic fibrosis and other diseases that affect the lung. We previously found that marker gene expression did not persist in the bronchial epithelium following adeno-associated virus (AAV) vector administration to the rabbit lung. In an attempt to promote continued expression, we tested repeat vector administration, but no additional transduction was observed, and the block to transduction correlated with the appearance of neutralizing antibodies to the viral capsid. Here we show that mice exhibit a similar response but that treatment with anti-CD40 ligand antibody (MR1) and a soluble CTLA4-immunoglobulin fusion protein (CTLA4Ig) at the time of primary AAV vector exposure allowed successful repeat transduction and prevented production of neutralizing antibodies. We also tested the possibility that an immune response caused the loss of marker-positive cells in the epithelial population in rabbits by evaluating AAV vector expression in immunocompetent and immunodeficient mice. In contrast to results in rabbits, marker protein expression persisted in the lung in both groups of mice. AAV vector transduction occurred in alveolar cells, airway epithelial cells, and smooth muscle cells, and vector expression persisted for at least 8 months. Although data on persistence of AAV vector expression in the human lung are not available, it is likely that repeat transduction will be necessary either due to loss of expression or to the need for repeat administration to deliver effective amounts of AAV vectors. Results presented here indicate that transient immunosuppression will allow such repeat vector treatment of the lung.


2019 ◽  
Author(s):  
Chikako Arai ◽  
Aki Suyama ◽  
Shigeyuki Arai ◽  
Norie Arai ◽  
Chiyo Yoshizane ◽  
...  

Abstract Background: Trehalose is a functional disaccharide that has anti-metabolic activities such as suppression of adipocyte hypertrophy in mice and alleviation of impaired glucose tolerance in humans. Trehalase hydrolyzes trehalose in the small intestine into two glucose molecules. In this study, we investigated whether trehalose can suppress adipocyte hypertrophy in mice in the presence or absence of trehalase. Methods: Trehalase knockout (KO) mice and wild-type (WT) mice were fed a high fat diet (HFD) and administered water with 0.3% (w/v) or without trehalose for 8 weeks. At the end of the experimental period, mesenteric adipose tissues and the small intestine were collected and the adipocyte size and proportion of cytoplasmic lipid droplets (CLDs, %) in jejunum epithelium were measured by image analysis. Results: Trehalose treatment was associated with suppressed adipocyte hypertrophy in both trehalase KO and WT mice. The rate of CLDs in the jejunal epithelium was increased in both trehalase KO and WT mice given water containing trehalose relative to untreated control mice. Since there was a negative correlation between jejunal epithelial lipid droplet volume and mesenteric adipocyte size, together with these results, trehalose treatment would suppress adipocyte hypertrophy. Because of jejunal epithelium containing lipid droplets falled into the intestinal lumen, triglyceride (TG) levels in feces tended to be higher in the KO/HFD/Tre group than in the KO/HFD/Water group. Whereas feces from trehalose-treated trehalase KO and WT mice tended to have more free fatty acids (FFA) than the untreated groups. Chylomicron-TG tended to be decreased in both trehalose-treated trehalase KO and WT mice. In vitro , addition of trehalose to differentiated Caco-2 cells increased intracytoplasmic lipid droplets and decreased secretion of the chylomicron marker ApoB48. Conclusions: The suppression of adipocyte hypertrophy in the presence and absence of trehalase indicates that trehalose mediates effects prior to being hydrolyzed into glucose. In both trehalase KO and WT mice, trehalose treatment increased the rate of CLDs in jejunal epithelium, reduced chylomicron migration from the intestinal epithelium to the periphery, and suppressed adipocyte hypertrophy. Thus, trehalose ingestion could prevent metabolic syndrome by trapping fat droplets in the intestinal epithelium and suppressing rapid increases in chylomicrons.


1991 ◽  
Vol 58 (4) ◽  
pp. 485-496 ◽  
Author(s):  
Gabriela Perdigón ◽  
Susana Alvarez ◽  
Aída Pesce de Ruiz Holgado

SummaryLactobacilli, often used as effectors of host functions, could play an important role in maintaining human health by controlling other intestinal microorganisms capable of producing harmful effects. Using an experimental model, we studied the effect of different oral doses ofLactobacillus caseion the secretory IgA response and the protective capacity of the microorganism in preventing intestinal infections. The optimization of the protective dose ofLb. caseiby previous feeding and the use of the lactobacillus as an immunological way to control enteric infections were investigated. We found that conventional mice were protected against infection withSalmonella typhimuriumandEscherichia coliby previous feeding for 2 consecutive days with a dailyLb. caseidose of 1·2 × 109cfu/mouse. Previous feeding for 7 d proved less effective, and feeding for 5 d afforded no protection at all. We were also able to demonstrate that the protective effect ofLb. caseiagainstSal. typhimuriumandEsch. coliwas connected mainly with the high level of IgA antipathogen antibodies present in intestinal secretions. β-Glucuronidase (EC 3.2.1.31) and β-galactosidase (EC 3.2.1.23) activities, measured both in the intestinal fluid and histological samples, showed a marked increase in intestinal inflammatory response on day 5 of feeding. These results show thatLb. caseiplays an important role in the prevention of enteric infections, a low dose being enough for protection against intestinal infections by increasing IgA secretion into the intestinal lumen, thus providing adequate defences for the mucosal surface. A previously administered dose of this magnitude could therefore be used as an oral adjuvant in preventing enteric infections.


2020 ◽  
Author(s):  
Vivian Gonzalez-Perez ◽  
Pedro L. Martinez-Espinosa ◽  
Monica Sala-Rabanal ◽  
Nikhil Bharadwaj ◽  
Xiao-Ming Xia ◽  
...  

AbstractGoblet cells (GCs) are specialized cells of the intestinal epithelium contributing critically to mucosal homeostasis. One of the functions of GCs is to produce and secrete MUC2, the mucin that forms the scaffold of the intestinal mucus layer coating the epithelium and separates the luminal pathogens and commensal microbiota from the host tissues. Although a variety of ion channels and transporters are thought to impact on MUC2 secretion, the specific cellular mechanisms that regulate GC function remain incompletely understood. Previously, we demonstrated that leucine-rich-repeat-containing protein 26 (LRRC26), a known regulatory subunit of the Ca2+-and voltage-activated K+ channel (BK channel), localizes specifically to secretory cells within the intestinal tract. Here, utilizing a mouse model in which MUC2 is fluorescently tagged allowing visualization of single GCs in intact colonic crypts, we show that murine colonic GCs have functional LRRC26-associated BK channels. In the absence of LRRC26, BK channels are present in GCs, but are not activated at physiological conditions. In contrast, all tested MUC2-negative cells completely lacked BK channels. Moreover, LRRC26-associated BK channels underlie the BK channel contribution to the resting transepithelial current across mouse distal colonic mucosa. Genetic ablation of either LRRC26 or BK-pore forming α-subunit in mice results in a dramatically enhanced susceptibility to colitis induced by dextran sodium sulfate (DSS). These results demonstrate that normal potassium flux through LRRC26-associated BK channels in GCs has protective effects against colitis in mice.SignificanceA primary function of goblet cells (GCs) of the intestinal epithelium is to generate a protective mucus layer lining the intestinal lumen. GC dysfunction is linked to Inflammatory Bowel Disease (IBD). GC mucus secretion is thought to be dependent on contributions of an ensemble of anion and cation fluxes, although understanding remains limited. Here, it is shown in mouse colon that the Ca2+- and voltage-dependent BK-type K+ channel, specifically in association with the LRRC26 regulatory subunit, plays a critical role in normal GC function, protecting mice against chemically-induced colitis. The results demonstrate that normal K+ fluxes mediated by LRRC26-containing BK channels are required for normal GC function, potentially providing insights into the potential role of BK channels in IBD.


2021 ◽  
Author(s):  
Shuyi Xu ◽  
Shiyi Lu ◽  
Haichao Wang ◽  
Sisi Li ◽  
Jie Feng

Abstract Background: Hyperosmotic stress resulting from lumen contents is a big challenge to the normal function of the intestinal epithelium. Betaine is a potent organic osmolyte, but it is mostly studied in kidney. The purpose of this study was to gain insight into the osmoprotectant role of betaine in intestinal epithelium of piglets and intestinal porcine epithelial cells (IPEC-J2 cells) under hyperosmotic condition.Results: The result showed that the osmolarity of intestinal chyme was much higher than that of plasma (P < 0.05), indicating a natural hyperosmotic environment of intestinal lumen and subsequently leading to hyperosmotic stress to intestinal epithelium. Meanwhile, hyperosmolarity corresponding to intestinal environment was simulated by 150 mmol/L NaCl in vitro and caused a significant decrease of cell viability (P < 0.05). It was found that betaine could remarkably decrease hyperosmolarity-induced reactive oxygen species (ROS) of intestinal epithelium in vivo and vitro (P < 0.05) with the significant restoration of cell shrinkage (P < 0.05). Furthermore, since hyperosmolarity caused mitochondrial-related apoptosis with the remarkable increase of cleaved Caspase3, cleaved PARP-1, cytoplasm cytochrome c as well as obvious decrease of Bcl-2 in protein level (P < 0.05), betaine prevented mitochondria from membrane collapse and alleviated apoptosis (P < 0.05) in vivo and vitro. Meanwhile, it was also confirmed that betaine reduced hyperosmotic stress-induced apoptotic incidence in IPEC-J2 cells via fluorescence microscope and flow cytometry (P < 0.05). In addition, betaine supplementation significantly suppressed hyperosmotic stress-induced elevated expression of LC3 II and reduced expression of p62 (P < 0.05). indicating that betaine ameliorated autophagy of porcine intestinal epithelium caused by hyperosmolarity in vivo and vitro. Autophagic flux determined by mRFP-GFP-LC3B system in IPEC-J2 cells was in agreement with the result of western blotting as well (P < 0.05). Conclusions: Betaine could alleviate hyperosmotic stress-induced cell shrinkage, ROS accumulation as well as ameliorate subsequently apoptosis and autophagy in small intestinal epithelium of piglets and IPEC-J2 cells.


2020 ◽  
Author(s):  
Chikako Arai ◽  
Aki Suyama ◽  
Shigeyuki Arai ◽  
Norie Arai ◽  
Chiyo Yoshizane ◽  
...  

Abstract Background: Trehalose is a functional disaccharide that has anti-metabolic activities such as suppression of adipocyte hypertrophy in mice and alleviation of impaired glucose tolerance in humans. Trehalase hydrolyzes trehalose in the small intestine into two glucose molecules. In this study, we investigated whether trehalose can suppress adipocyte hypertrophy in mice in the presence or absence of trehalase. Methods: Trehalase knockout (KO) mice and wild-type (WT) mice were fed a high fat diet (HFD) and administered water with 0.3% (w/v) or without trehalose for 8 weeks. At the end of the experimental period, mesenteric adipose tissues and the small intestine were collected and the adipocyte size and proportion of cytoplasmic lipid droplets (CLDs, %) in jejunum epithelium were measured by image analysis. Results: Trehalose treatment was associated with suppressed adipocyte hypertrophy in both trehalase KO and WT mice. The rate of CLDs in the jejunal epithelium was increased in both trehalase KO and WT mice given water containing trehalose relative to untreated control mice. There was a negative correlation between jejunal epithelial lipid droplet volume and mesenteric adipocyte size. Chylomicron-TG tended to be decreased in both trehalose-treated trehalase KO and WT mice. Addition of trehalose to differentiated Caco-2 cellsin vitro increased intracytoplasmic lipid droplets and decreased secretion of the chylomicron marker ApoB-48. Moreover, the jejunal epithelium containing lipid droplets falled into the intestinal lumen, and triglyceride (TG) levels in feces tended to be higher in the KO/HFD/Tre group than in the KO/HFD/Water group. Since then, the accumulation of CLDs has been reported to suppress CM secretion, and along with our results, the effect of trehalose to increase jejunum CLDs may induce adipocyte hypertrophy. Conclusions: The suppression of adipocyte hypertrophy in the presence and absence of trehalase indicates that trehalose mediates effects prior to being hydrolyzed into glucose. In both trehalase KO and WT mice, trehalose treatment increased the rate of CLDs in jejunal epithelium, reduced chylomicron migration from the intestinal epithelium to the periphery, and suppressed adipocyte hypertrophy. Thus, trehalose ingestion could prevent metabolic syndrome by trapping fat droplets in the intestinal epithelium and suppressing rapid increases in chylomicrons.


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