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Variable stretch reduces the pro-inflammatory response of alveolar epithelial cells.

ABSTRACT: Mechanical ventilation has the potential to increase inflammation in both healthy and injured lungs. Several animal studies have shown that variable ventilation recruits the lungs and reduces inflammation. However, it is unclear which cellular mechanisms are involved in those findings. We hypothesized that variable stretch of LPS-stimulated alveolar epithelial cells (AECs) reduces the production of pro-inflammatory cytokines compared to non-variable stretch. AECs were subjected to non-variable or variable cyclic stretch (sinusoidal pattern), with and without LPS stimulation. The expression and release of interleukin-6, CXCL-2 and CCL-2 mRNA were analyzed after 4 hours. The phosphorylation of the MAPKs ERK1/2 and SAPK/JNK was determined by Western Blot analysis at 0, 15, 30, 45 and 60 min of cyclic stretch. In LPS-stimulated AECs, variable cyclic cell stretching led to reduced cytokine expression and release compared to non-variable cell stretching. Furthermore, the phosphorylation of the MAPK ERK1/2 was increased after 30 minutes in non-variable stretched AECs, whereas variable stretched cells demonstrated only the non-stretched level of phosphorylation. After the 4h period of cyclic cell stretch and inhibition of the ERK1/2, but not the SAPK/JNK, signaling pathway, the gene expression of investigated cytokines increased in variable stretched, and decreased in non-variable stretched AECs. We conclude that in LPS-stimulated AECs, variable stretch reduced the pro-inflammatory response compared to non-variable stretch. This effect was mediated by the ERK1/2 signaling pathway, and might partly explain the findings of reduced lung inflammation during mechanical ventilation modes that enhance breath-by-breath variability of the respiratory pattern.

SUBMITTER: Rentzsch I

PROVIDER: S-EPMC5557541 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Variable stretch reduces the pro-inflammatory response of alveolar epithelial cells.

Rentzsch Ines I Santos Cíntia L CL Huhle Robert R Ferreira Jorge M C JMC Koch Thea T Schnabel Christian C Koch Edmund E Pelosi Paolo P Rocco Patricia R M PRM Gama de Abreu Marcelo M

PloS one 20170815 8

Mechanical ventilation has the potential to increase inflammation in both healthy and injured lungs. Several animal studies have shown that variable ventilation recruits the lungs and reduces inflammation. However, it is unclear which cellular mechanisms are involved in those findings. We hypothesized that variable stretch of LPS-stimulated alveolar epithelial cells (AECs) reduces the production of pro-inflammatory cytokines compared to non-variable stretch. AECs were subjected to non-variable o ...[more]

PMID: 28813446

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Project description:Infants affected by Hirschsprung disease (HSCR), a neurodevelopmental congenital disorder, lack ganglia of the intrinsic enteric nervous system (aganglionosis) in a variable length of the colon, and are prone to developing severe Hirschsprung-associated enterocolitis (HAEC). HSCR patients typically show abnormal dense innervation of extrinsic cholinergic nerve fibers throughout the aganglionic rectosigmoid. Cholinergic signaling has been reported to reduce inflammatory response. Consequently, a sparse extrinsic cholinergic innervation in the mucosa of the rectosigmoid correlates with increased inflammatory immune cell frequencies and higher incidence of HAEC in HSCR patients. However, whether cholinergic signals influence the pro-inflammatory immune response of intestinal epithelial cells (IEC) is unknown. Here, we analyzed colonic IEC isolated from 43 HSCR patients with either a low or high mucosal cholinergic innervation density (fiber-low versus fiber-high) as well as from control tissue. Compared to fiber-high samples, IEC purified from fiber-low rectosigmoid expressed significantly higher levels of IL-8 but not TNF-α, IL-10, TGF-β1, Muc-2 or tight junction proteins. IEC from fiber-low rectosigmoid showed higher IL-8 protein concentrations in cell lysates as well as prominent IL-8 immunoreactivity compared to IEC from fiber-high tissue. Using the human colonic IEC cell line SW480 we demonstrated that cholinergic signals suppress lipopolysaccharide-induced IL-8 secretion via the alpha 7 nicotinic acetylcholine receptor (a7nAChR). In conclusion, we showed for the first time that the presence of a dense mucosal cholinergic innervation is associated with decreased secretion of IEC-derived pro-inflammatory IL-8 in the rectosigmoid of HSCR patients likely dependent on a7nAChR activation. Owing to the association between IL-8 and enterocolitis-prone, fiber-low HSCR patients, targeted therapies against IL-8 might be a promising immunotherapy candidate for HAEC treatment.

Project description:The aim of the present study was to explore the potential role of SOX11 in the stretch‑induced mechanical injury to alveolar type 2 epithelial (AT2) cells. A cell stretch (CS) test was used to induce mechanical injury to primary cultured AT2 cells. Wound healing, adhesion, cell viability assays and flow cytometry were performed to evaluate the migration, adhesion, viability and apoptosis of AT2 cells. Changes in the invasive ability of AT2 cells were detected using a Transwell invasion assay. To further explore the underlying molecular mechanisms, reverse transcription‑quantitative PCR and western blot analysis were used to assess the expression levels of SOX11, FAK, Akt, caspase‑3/8, p65 and matrix metalloproteinase (MMP)7. Co‑immunoprecipitation (Co‑IP) and luciferase reporter assays were used to detect the interaction between SOX11 and FAK. CS reduced the invasion, migration and adhesion, and increased the apoptosis of AT2 cells. It also resulted in the downregulation of SOX11 and FAK expression in AT2 cells. The overexpression of SOX11 reversed these changes, whereas the knockdown of SOX11 aggravated the deterioration of the aforementioned biological behaviors and the apoptosis of the AT2 cells following CS. The overexpression of SOX11 upregulated the FAK and Akt expression levels, and downregulated caspase‑3/8 expression, whereas the silencing of SOX11 reversed these changes following CS. Furthermore, the effects of SOX11 overexpression were inhibited by FAK antagonism. The results of Co‑IP demonstrated that SOX11 and FAK were bound together, and that the expression of FAK was significantly increased in the SOX11 overexpression group. Luciferase assays revealed that the luciferase activity and the mRNA expression of FAK were significantly increased following transfection with pcDNA SOX11 and pGL3 FAK promoter. Co‑IP and luciferase assays revealed that SOX11 directly regulated the expression of FAK. On the whole, the present study demonstrates that the downregulated expression of SOX11 and FAK are involved in the stretch‑induced mechanical injury to AT2 cells. The overexpression of SOX11 significantly alleviates AT2 cell injury through the upregulation of FAK and Akt, and the inhibition of apoptosis. These findings suggest that the activation of SOX11 and FAK may be potential preventive and therapeutic options for ventilator‑induced lung injury.

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Variable stretch reduces the pro-inflammatory response of alveolar epithelial cells.

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Variable stretch reduces the pro-inflammatory response of alveolar epithelial cells.

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