Damage Of Epithelial Layer Research Articles

Stanniocalcin-1 secreted by human umbilical mesenchymal stem cells regulates interleukin-10 expression via the PI3K/AKT/mTOR pathway in alveolar macrophages.

Acute respiratory distress syndrome (ARDS) is a syndrome of acute respiratory failure caused by infection, trauma, shock, aspiration or drug reaction. The pathogenesis of ARDS is characterized as an unregulated inflammatory storm, which causes endothelial and epithelial layer damage, leading to alveolar fluid accumulation and pulmonary edema. Previous studies have shown the potential role of mesenchymal stem cells (MSC) in combating the inflammatory cascade by increasing the anti-inflammatory mediator interleukin-10 (IL-10). However, the involved mechanisms are unclear. Here we investigated whether a key immunomodulatory regulator, stanniocalcin-1 (STC-1), was secreted by MSC to activate phosphoinositide 3-kinase/protein kinase B (PI3K/AKT)/ mammalian target of rapamycin (mTOR) signaling pathway to increase IL-10 expression in alveolar macrophages. Lipopolysaccharide (LPS)-stimulated alveolar macrophages co-cultured with human umbilical mesenchymal stem cells (HUMSC) secreted high levels of IL-10. HUMSC co-cultured with alveolar macrophages expressed high STC-1 levels and increased PI3K, AKT and mTOR phosphorylation after LPS activation in alveolar macrophages. STC-1 knockdown in HUMSC decreased the phosphorylation of PI3K, AKT and mTOR and suppressed IL-10 expression in alveolar macrophages. Rapamycin (an mTOR inhibitor) reduced IL-10 secretion in alveolar macrophages. These results, together with our previous study and others, indicate that the PI3K/AKT/mTOR pathway is involved in the regulation of IL-10 production by STC-1 secreted by HUMSC in alveolar macrophages.

3D Oral Mucosal Models for Studying Host-Pathogen Interactions in Periodontal Disease

The host immune response to the oral biofilm plays a central role in the aetiology of periodontitis. Our understanding of hostpathogen interactions has historically been reliant on monolayer culture systems stimulated by microorganisms. However, 2D culture systems possess major shortcomings as these do not adequately mimic the complexities of the native tissue and therefore fail to provide meaningful information on the pathogenesis of periodontal disease. To mimic the in vivo condition, various types of 3D oral mucosal equivalents (OME) have been employed, including reconstituted models and 3D organotypic culture models. The rationale for OME is to serve as a relevant in vitro tool to examine the interactions of human epithelial cells with bacterial biofilms, to understand the process of epithelial layer damage, molecular mechanisms underpinning the development of periodontitis and models for testing novel therapeutics. Furthermore, to gain a deeper understanding of periodontal dysbiosis, it is important to appreciate the molecular mechanisms underlying host epithelial cell production of cytokines and chemokines in response to bacterial stimulation; and signalling pathways which underpin host-pathogen interactions such as mitogen-activated protein kinases (MAPK) and nuclear factor kappa light chain enhancer of activated B cells (NFkB). Thus, the aim of this narrative review is to summarise the evidence regarding the application of 3D oral mucosal models in host-pathogen infection studies relating to periodontal disease, review the molecular mechanisms underlying host response and provide recommendations for future studies in this field.

Expression of a BTB-ZF transcription factor controls the function of an innate-like Tregs essential for intestinal homeostasis

Abstract The BTB-ZF genes are a family of 49 transcription factors that control the lineage specification and development of key effector functions of different subsets of lymphocytes. Using a single-cell BTB-ZF transcription factor expression analysis, we identified a unique subset of T regulatory cells (Tregs). These Tregs are genetically and phenotypically distinct from the larger conventional Treg population. For instance, analogous to natural killer (NKT) cells they have an activated phenotype (CD62Llo, CD44hi) and constitutively express IL-10. Interestingly, these characteristics are acquired early during T cell development. The defining transcription factor is induced during thymic development, binds the IL-10 promoter, and enables T cells to rapidly produce the cytokine. The subset of Tregs is enriched in the intestine and expands during acute colitis. The deletion of the defining transcription factor in T cells results in intestinal epithelial layer damage causing loss of the barrier function making mice highly vulnerable to severe disease and death from induced colitis. Moreover, in the absence of the transcription factor in T cells, normal intestinal macrophage responses are disrupted most likely due to decreased production of IL-10 by the Tregs. Therefore, by profiling BTB-ZF transcription factor expression, we have identified a distinct subset of T cells with potent immunosuppressive abilities that are essential for the health of the intestine. Numerous aspects of these Tregs are parallel to NKT cells, indicating an existence of “naïve” Tregs that have innate-like effector functions acquired independently from the differentiation in the periphery. Supported by NIH/NIAID R01 AI122757-01 Careers in Immunology Fellowships – 2021

Two-Stage Interpretation of Changes in TEER of Intestinal Epithelial Layers Protected by Adhering Bifidobacteria During E. coli Challenges.

Mechanisms of gastrointestinal protection by probiotic bacteria against infection involve amongst others, modulation of intestinal epithelial barrier function. Trans-epithelial electrical resistance (TEER) is widely used to evaluate cellular barrier functions. Here, we developed a two-stage interpretative model of the time-dependence of the TEER of epithelial layers grown in a transwell during Escherichia coli challenges in the absence or presence of adhering bifidobacteria. E. coli adhesion in absence or presence of adhering bifidobacteria was enumerated using selective plating. After 4–8 h, E. coli challenges increased TEER to a maximum due to bacterial adhesion and increased expression of a tight-junction protein [zonula occludens-1 (ZO-1)], concurrent with a less dense layer structure, that is indicative of mild epithelial layer damage. Before the occurrence of a TEER-maximum, decreases in electrical conductance (i.e., the reciprocal TEER) did not relate with para-cellular dextran-permeability, but after occurrence of a TEER-maximum, dextran-permeability and conductance increased linearly, indicative of more severe epithelial layer damage. Within 24 h after the occurrence of a TEER maximum, TEER decreased to below the level of unchallenged epithelial layers demonstrating microscopically observable holes and apoptosis. Under probiotic protection by adhering bifidobacteria, TEER-maxima were delayed or decreased in magnitude due to later transition from mild to severe damage, but similar linear relations between conductance and dextran permeability were observed as in absence of adhering bifidobacteria. Based on the time-dependence of the TEER and the relation between conductance and dextran-permeability, it is proposed that bacterial adhesion to epithelial layers first causes mild damage, followed by more severe damage after the occurrence of a TEER-maximum. The mild damage caused by E. coli prior to the occurrence of TEER maxima was reversible upon antibiotic treatment, but the severe damage after occurrence of TEER maxima could not be reverted by antibiotic treatment. Thus, single-time TEER is interpretable in two ways, depending whether increasing to or decreasing from its maximum. Adhering bifidobacteria elongate the time-window available for antibiotic treatment to repair initial pathogen damage to intestinal epithelial layers.

Nrf2 transcriptional activity in the mouse affects the physiological response to tribromoethanol

Up to date, there is no information on the influence of 2,2,2-tribromoethanol (TBE; Avertin), a commonly used anaesthetic, on mice with impaired antioxidant capacity. We aimed to analyse the effect of a single dose of Avertin on anaesthesia duration time, inflammatory response, oxidative stress and collagen deposition in the large intestine of Nrf2 transcriptional knockout mice (tNrf2−/−). The studies were performed on six-month-old female mice Nrf2+/+ and tNrf2−/− randomly assigned to Avertin (250 mg/kg b.w. single i.p. injection) or vehicle group. We observed a 2-fold increase in anaesthesia time and longer recovery time (p = 0.015) in tNrf2−/− in comparison to Nrf2+/+. However, no hepato- or nephrotoxicity was detected. Interestingly, we found severe changes in colon morphology of untreated tNrf2-/- mice associated with colon shortening (p = 0.02) and thickening (p = 0.015). Avertin treatment caused colon damage manifested with epithelial layer damage and goblet depletion in Nrf2+/+ mice but not in tNrf2−/− individuals. Additionally, Avertin did not induce oxidative stress in colon tissue, but it increased leukocyte infiltration in Nrf2+/+ mice (p = 0.02). Immunofluorescent staining also revealed enhanced deposition of collagen I and collagen III in the colon of untreated tNrf2−/− mice. Avertin contributed to increased deposition of collagen I in Nrf2+/+ mice but reduced deposition of collagen I and III in tNrf2−/− individuals. In conclusion, tNrf2−/− respond to Avertin with prolonged anaesthesia that is not associated with acute toxicity, inflammatory reaction or enhanced oxidative stress. Avertin does not impair intestine morphology in tNrf2−/− mice but can normalise the enhanced fibrosis.

Mesenchymal stem cell use in acute respiratory distress syndrome: a potential therapeutic application.

Acute respiratory distress syndrome (ARDS) is a condition of acute respiratory failure resulting from noncardiogenic pulmonary edema. It may occur as a consequence of lung infection, sepsis, trauma, aspiration or drug reaction. The pathogenesis of ARDS is understood to be an unregulated inflammatory cascade with both endothelial and epithelial layer damage leading to alveolar fluid collection and pulmonary edema. Despite improved understanding of the cause of ARDS, treatment remains supportive with a mortality rate ranging from 25–40%. Preclinical and early phase clinical trials have highlighted the potential role of mesenchymal stem cells in combating the inflammatory cascade through immunomodulatory mechanisms and assisting in tissue repair.

In Vivo Effects of Cagaita (Eugenia dysenterica, DC.) Leaf Extracts on Diarrhea Treatment

Eugenia dysenterica is a plant typically found in the Cerrado biome and commonly used in popular medicine due to its pharmacological properties, which include antidiarrheal, skin healing, and antimicrobial activities. The effects of ethanolic extract, aqueous extract and infusion of E. dysenterica leaves on intestinal motility and antidiarrheal activity were evaluated using ricin oil-induced diarrhea in rats. At doses of 400 and 800 mg·Kg−1, the ethanolic extract decreased intestinal motility while the other extracts showed no significant effects. Moreover, serum levels of chloride, magnesium, and phosphorus were also measured in rats. Histopathologic and enzymatic analyses were also performed to investigate any toxic effect. Animals treated with infusion, ethanolic extract, ricin oil, and loperamide presented morphological alterations in the small intestine, such as mucosa lesion, epithelial layer damage, and partial loss and/or morphological change of villi. Furthermore, the liver showed congestion and hydropic degeneration. Serum levels of alanine aminotransferase increased significantly in all treatments, but none rose above reference values. In summary, our results suggest that compounds present in leaves of E. dysenterica may have therapeutic benefits on recovery from diarrhea despite their toxic effects.

Effects of Lipopolysaccharide from <i>Pseudomonas aeruginosa</i> on Airway Smooth Muscle Functions in Guinea Pigs

To elucidate the mechanisms of airway hyperreactivity induced by lipopolysaccharide (LPS), we studied isolated tracheal segments from guinea pigs under isometric conditions in vitro. Guinea pigs were injected intraperitoneally with endotoxin (1 mg/kg; LPS from Pseudomonas aeruginosa, serotype 10) for 4 days, and animals treated with sterile nonpyrogenic saline served as controls. Histological examination of trachea revealed moderate structural damage of epithelial layer in the LPS-treated group. Treatment with LPS potentiated the contractile responses of tracheal smooth muscle to acetylcholine, causing a leftward displacement of dose-response curves so that the EC50 values decreased from 1.1 +/- 3.7 x 10(-5) to 4.4 +/- 3.7 x 10(-7) M (mean +/- SE, p less than 0.01). Likewise, LPS shifted the dose-response curves for histamine and substance P to lower concentrations by approximately 0.5-1.0 log U. Each of these potentiations was not affected by pretreatment of tissues with indomethacin or propranolol. Addition of isoproterenol to tracheal segments precontracted with acetylcholine caused concentration-dependent relaxation, an effect that was significantly greater in controls than in the LPS-treated group. These results suggest that airway hyperreactivity induced by LPS in guinea pigs may be attributed to a decreased ability of respiratory epithelial cells to generate a relaxing factor.