Dataset Information

Dexamethasone Attenuates X-Ray-Induced Activation of the Autotaxin-Lysophosphatidate-Inflammatory Cycle in Breast Tissue and Subsequent Breast Fibrosis.

ABSTRACT: We recently showed that radiation-induced DNA damage in breast adipose tissue increases autotaxin secretion, production of lysophosphatidate (LPA) and expression of LPA_1/2 receptors. We also established that dexamethasone decreases autotaxin production and LPA signaling in non-irradiated adipose tissue. In the present study, we showed that dexamethasone attenuated the radiation-induced increases in autotaxin activity and the concentrations of inflammatory mediators in cultured human adipose tissue. We also exposed a breast fat pad in mice to three daily 7.5 Gy fractions of X-rays. Dexamethasone attenuated radiation-induced increases in autotaxin activity in plasma and mammary adipose tissue and LPA₁ receptor levels in adipose tissue after 48 h. DEX treatment during five daily fractions of 7.5 Gy attenuated fibrosis by ~70% in the mammary fat pad and underlying lungs at 7 weeks after radiotherapy. This was accompanied by decreases in CXCL2, active TGF-β1, CTGF and Nrf2 at 7 weeks in adipose tissue of dexamethasone-treated mice. Autotaxin was located at the sites of fibrosis in breast tissue and in the underlying lungs. Consequently, our work supports the premise that increased autotaxin production and lysophosphatidate signaling contribute to radiotherapy-induced breast fibrosis and that dexamethasone attenuated the development of fibrosis in part by blocking this process.

SUBMITTER: Meng G

PROVIDER: S-EPMC7226295 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Dexamethasone Attenuates X-Ray-Induced Activation of the Autotaxin-Lysophosphatidate-Inflammatory Cycle in Breast Tissue and Subsequent Breast Fibrosis.

Meng Guanmin G Wuest Melinda M Tang Xiaoyun X Dufour Jennifer J McMullen Todd P W TPW Wuest Frank F Murray David D Brindley David N DN

Cancers 20200418 4

We recently showed that radiation-induced DNA damage in breast adipose tissue increases autotaxin secretion, production of lysophosphatidate (LPA) and expression of LPA<sub>1/2</sub> receptors. We also established that dexamethasone decreases autotaxin production and LPA signaling in non-irradiated adipose tissue. In the present study, we showed that dexamethasone attenuated the radiation-induced increases in autotaxin activity and the concentrations of inflammatory mediators in cultured human a ...[more]

PMID: 32325715

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Project description:Lysophosphatidate (LPA)-mediated signaling is a vital component of physiological wound healing, but the pathway is subverted to mediate chronic inflammatory signaling in many pathologies, including cancers. LPA, as an extracellular signaling molecule, is produced by the enzyme autotaxin (ATX, gene name ENPP2) and signals through six LPA receptors (LPARs). Its signaling is terminated by turnover via the ecto-activity of three lipid phosphate phosphatases (LPPs, gene names PLPP1-3). Many pharmacological developments against the LPA-signaling axis are underway, primarily against ATX. An ATX inhibitor against pancreatic ductal adenocarcinoma (PDAC), a very aggressive disease with limited systemic therapeutic options, is currently in clinical trials, and represents the first in-class drug against LPA signaling in cancers. In the present study, we surveyed the expression of ATX, LPARs, and LPPs in human PDACs and their clinical outcomes in two large independent cohorts, the Cancer Genome Atlas (TCGA) and GSE21501. Correlation among gene expressions, biological function and the cell composition of the tumor microenvironment were analysed using gene set enrichment analysis and cell cyber-sorting with xCell. ENPP2, LPAR1, LPAR4, LPAR5, LPAR6, PLPP1, and PLPP2 were significantly elevated in PDACs compared to normal pancreatic tissue, whereas LPAR2, LPAR3, and PLPP3 where downregulated (all P≤0.003). Only ENPP2 demonstrated survival differences, with overall survival favoring ENPP2-high patients (hazard ration 0.5-0.9). ENPP2 was also the only gene with enriched gene patterns for inflammatory and tissue repair gene sets. Epithelial (cancer) cells had increased LPAR2, LPAR5 and PLPP2 expression, and decreased ENPP2, LPAR1, PLPP1, and PLPP3 gene expression (all P<0.02). Tumor fibroblasts had increased ENPP2, LPAR2, LPAR4, PLPP1, and PLPP3 expression and decreased LPAR2, LPAR5, and PLPP2 expression in both cohorts (all P≤0.01). Immune cell populations were not well correlated to gene expression in PDACs, but across both cohorts, cytolytic scores were increased in high-expressing ENPP2, LPAR1, LPAR6, PLPP1, and PLPP3 tumors (P<0.01). Overall, in PDACs, ENPP2 may switch from an anti-to-pro tumor promoting gene with disease progression. LPAR2 and PLPP2 inhibition are also predicted to have potential therapeutic utility. Future multi-omics investigations are necessarily to validate which LPA signaling components are high-value candidates for pharmacological manipulation in PDAC treatment.

Project description:Sepsis patients are at increased risk for hospital-acquired pulmonary infections, potentially due to postseptic immunosuppression known as the compensatory anti-inflammatory response syndrome (CARS). CARS has been attributed to leukocyte dysfunction, with an unclear role for endothelial cells. The pulmonary circulation is lined by an endothelial glycocalyx, a heparan sulfate-rich layer essential to pulmonary homeostasis. Heparan sulfate degradation occurs early in sepsis, leading to lung injury. Endothelial synthesis of new heparan sulfates subsequently allows for glycocalyx reconstitution and endothelial recovery. We hypothesized that remodeling of the reconstituted endothelial glycocalyx, mediated by alterations in the endothelial machinery responsible for heparan sulfate synthesis, contributes to CARS. Seventy-two hours after experimental sepsis, coincident with glycocalyx reconstitution, mice demonstrated impaired neutrophil and protein influx in response to intratracheal lipopolysaccharide (LPS). The postseptic reconstituted glycocalyx was structurally remodeled, with enrichment of heparan sulfate disaccharides sulfated at the 6-O position of glucosamine. Increased 6-O-sulfation coincided with loss of endothelial sulfatase-1 (Sulf-1), an enzyme that specifically removes 6-O-sulfates from heparan sulfate. Intravenous administration of Sulf-1 to postseptic mice restored the pulmonary response to LPS, suggesting that loss of Sulf-1 was necessary for postseptic suppression of pulmonary inflammation. Endothelial-specific knockout mice demonstrated that loss of Sulf-1 was not sufficient to induce immunosuppression in non-septic mice. Knockdown of Sulf-1 in human pulmonary microvascular endothelial cells resulted in downregulation of the adhesion molecule ICAM-1. Taken together, our study indicates that loss of endothelial Sulf-1 is necessary for postseptic suppression of pulmonary inflammation, representing a novel endothelial contributor to CARS.

Project description:BackgroundAcute kidney injury (AKI) is an underestimated, yet important, risk factor for the development of chronic kidney disease (CKD). Persistence of inflammation after a renal ischemic injury has been observed, both in experimental models and patients, and is thought to be an important mechanisms underlying progression of acute-to-chronic renal injury. Temporary suppression of inflammation immediately after AKI might therefore be a good first-line therapeutic strategy towards a better long term outcome.MethodsMale C57Bl/6 J mice (Charles River, 10-12 weeks of age) underwent warm (36 °C body temperature) unilateral ischemia-reperfusion of the kidney for 21 min, after which treatment with intraperitoneal injection of the corticosteroid dexamethasone (10 mg/kg) was initiated for 3 weeks. Both at that time point and after an additional 3 week post-treatment follow up period, fibrosis was quantified by collagen I gene expression and immunostaining, as well as gene expression analysis of fibrosis-related genes Tgfβ, Ccn2 (Ctgf), Pai-1 and Ccn3. Furthermore, inflammation was evaluated by Tnfα gene expression and protein expression of the F4/80 macrophage marker and the α-SMA fibroblast marker. Lastly, renal histopathology was quantified by a morphometric analysis of the tubulointerstitial area.ResultsTreatment with dexamethasone attenuated development of fibrosis, as evidenced by reduced collagen I gene expression and immunostaining, in combination with reduced gene expression of the pro-fibrotic Ccn2 and increased expression of the anti-fibrotic Ccn3. The effects of dexamethasone on renal fibrosis persisted during the 3 week follow up period, as evidenced by stagnation of collagen I deposition in the ischemic kidney, in contrast to vehicle-treatment, where progression of fibrosis was observed. However, expression levels of the pro-fibrotic genes re-approached those of vehicle-treated injured kidneys suggesting that the effects of dexamethasone on fibrosis beyond the treatment period are temporary.ConclusionA short term anti-inflammatory therapy with dexamethasone only transiently attenuates ischemia induced fibrosis. Prolonged or persistent anti-inflammatory treatment seems warranted to achieve long term benefit.

Dataset Information

Dexamethasone Attenuates X-Ray-Induced Activation of the Autotaxin-Lysophosphatidate-Inflammatory Cycle in Breast Tissue and Subsequent Breast Fibrosis.

Publications

Dexamethasone Attenuates X-Ray-Induced Activation of the Autotaxin-Lysophosphatidate-Inflammatory Cycle in Breast Tissue and Subsequent Breast Fibrosis.

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