scholarly journals Adenosinergic signaling inhibits oxalate transport by human intestinal Caco2-BBE cells through the A2B adenosine receptor

2018 ◽  
Vol 315 (5) ◽  
pp. C687-C698 ◽  
Author(s):  
Daniel Jung ◽  
Altayeb Alshaikh ◽  
Sireesha Ratakonda ◽  
Mohamed Bashir ◽  
Ruhul Amin ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Adenosine Receptor ◽  
Surface Expression ◽  
Oxalate Secretion ◽  
Urine Oxalate ◽  
Inflammatory Bowel ◽  
Sirna Knockdown ◽  
Oxalate Transport ◽  
Exchange Activity

Most kidney stones (KS) are composed of calcium oxalate, and small increases in urine oxalate affect the stone risk. Intestinal oxalate secretion mediated by anion exchanger SLC26A6 (PAT1) plays a crucial role in limiting net absorption of ingested oxalate, thereby preventing hyperoxaluria and related KS, reflecting the importance of understanding regulation of intestinal oxalate transport. We previously showed that ATP and UTP inhibit oxalate transport by human intestinal Caco2-BBE cells (C2). Since ATP is rapidly degraded to adenosine (ADO), we examined whether intestinal oxalate transport is regulated by ADO. We measured [14C]oxalate uptake in the presence of an outward Cl gradient as an assay of Cl-oxalate exchange activity, ≥49% of which is PAT1-mediated in C2 cells. We found that ADO significantly inhibited oxalate transport by C2 cells, an effect completely blocked by the nonselective ADO receptor antagonist 8- p-sulfophenyltheophylline. ADO also significantly inhibited oxalate efflux by C2 cells, which is important since PAT1 mediates oxalate efflux in vivo. Using pharmacological antagonists and A2B adenosine receptor (A2B AR) siRNA knockdown studies, we observed that ADO inhibits oxalate transport through the A2B AR, phospholipase C, and PKC. ADO inhibits oxalate transport by reducing PAT1 surface expression as shown by biotinylation studies. We conclude that ADO inhibits oxalate transport by lowering PAT1 surface expression in C2 cells through signaling pathways including the A2B AR, PKC, and phospholipase C. Given higher ADO levels and overexpression of the A2B AR in inflammatory bowel disease (IBD), our findings have potential relevance to pathophysiology of IBD-associated hyperoxaluria and related KS.

scholarly journals Extracellular nucleotides inhibit oxalate transport by human intestinal Caco-2-BBe cells through PKC-δ activation

2013 ◽  
Vol 305 (1) ◽  
pp. C78-C89 ◽  
Author(s):  
Ruhul Amin ◽  
Sapna Sharma ◽  
Sireesha Ratakonda ◽  
Hatim A. Hassan
Keyword(s):  
Calcium Oxalate ◽  
Purinergic Receptor ◽  
Purinergic Signaling ◽  
Stone Formation ◽  
Surface Expression ◽  
Extracellular Nucleotides ◽  
Major Health Problem ◽  
Oxalate Secretion ◽  
Inflammatory Bowel ◽  
Oxalate Transport

Nephrolithiasis remains a major health problem in Western countries. Seventy to 80% of kidney stones are composed of calcium oxalate, and small changes in urinary oxalate affect risk of kidney stone formation. Intestinal oxalate secretion mediated by the anion exchanger SLC26A6 plays an essential role in preventing hyperoxaluria and calcium oxalate nephrolithiasis, indicating that understanding the mechanisms regulating intestinal oxalate transport is critical for management of hyperoxaluria. Purinergic signaling modulates several intestinal processes through pathways including PKC activation, which we previously found to inhibit Slc26a6 activity in mouse duodenal tissue. We therefore examined whether purinergic stimulation with ATP and UTP affects oxalate transport by human intestinal Caco-2-BBe (C2) cells. We measured [14C]oxalate uptake in the presence of an outward Cl−gradient as an assay of Cl−/oxalate exchange activity, ≥50% of which is mediated by SLC26A6. We found that ATP and UTP significantly inhibited oxalate transport by C2 cells, an effect blocked by the PKC inhibitor Gö-6983. Utilizing pharmacological agonists and antagonists, as well as PKC-δ knockdown studies, we observed that ATP inhibits oxalate transport through the P2Y2receptor, PLC, and PKC-δ. Biotinylation studies showed that ATP inhibits oxalate transport by lowering SLC26A6 surface expression. These findings are of potential relevance to pathophysiology of inflammatory bowel disease-associated hyperoxaluria, where supraphysiological levels of ATP/UTP are expected and overexpression of the P2Y2receptor has been reported. We conclude that ATP and UTP inhibit oxalate transport by lowering SLC26A6 surface expression in C2 cells through signaling pathways including the P2Y2purinergic receptor, PLC, and PKC-δ.

scholarly journals Cholinergic signaling inhibits oxalate transport by human intestinal T84 cells

2012 ◽  
Vol 302 (1) ◽  
pp. C46-C58 ◽  
Author(s):  
Hatim A. Hassan ◽  
Ming Cheng ◽  
Peter S. Aronson
Keyword(s):  
Calcium Oxalate ◽  
Signaling Pathways ◽  
Phospholipase C ◽  
Muscarinic Receptor ◽  
Surface Expression ◽  
Intestinal Cell ◽  
Common Disease ◽  
T84 Cells ◽  
Oxalate Secretion ◽  
Oxalate Transport

Urolithiasis remains a very common disease in Western countries. Seventy to eighty percent of kidney stones are composed of calcium oxalate, and minor changes in urinary oxalate affect stone risk. Intestinal oxalate secretion mediated by anion exchanger SLC26A6 plays a major constitutive role in limiting net absorption of ingested oxalate, thereby preventing hyperoxaluria and calcium oxalate urolithiasis. Using the relatively selective PKC-δ inhibitor rottlerin, we had previously found that PKC-δ activation inhibits Slc26a6 activity in mouse duodenal tissue. To identify a model system to study physiologic agonists upstream of PKC-δ, we characterized the human intestinal cell line T84. Knockdown studies demonstrated that endogenous SLC26A6 mediates most of the oxalate transport by T84 cells. Cholinergic stimulation with carbachol modulates intestinal ion transport through signaling pathways including PKC activation. We therefore examined whether carbachol affects oxalate transport in T84 cells. We found that carbachol significantly inhibited oxalate transport by T84 cells, an effect blocked by rottlerin. Carbachol also led to significant translocation of PKC-δ from the cytosol to the membrane of T84 cells. Using pharmacological inhibitors, we observed that carbachol inhibits oxalate transport through the M3 muscarinic receptor and phospholipase C. Utilizing the Src inhibitor PP2 and phosphorylation studies, we found that the observed regulation downstream of PKC-δ is partially mediated by c-Src. Biotinylation studies revealed that carbachol inhibits oxalate transport by reducing SLC26A6 surface expression. We conclude that carbachol negatively regulates oxalate transport by reducing SLC26A6 surface expression in T84 cells through signaling pathways including the M3 muscarinic receptor, phospholipase C, PKC-δ, and c-Src.

scholarly journals Activation of the PKA signaling pathway stimulates oxalate transport by human intestinal Caco2-BBE cells

2020 ◽  
Vol 318 (2) ◽  
pp. C372-C379
Author(s):  
Donna Arvans ◽  
Altayeb Alshaikh ◽  
Mohamed Bashir ◽  
Christopher Weber ◽  
Hatim Hassan
Keyword(s):  
Protein Expression ◽  
Signaling Pathway ◽  
Kidney Stones ◽  
Surface Protein ◽  
Intestinal Epithelial ◽  
T84 Cells ◽  
Urine Oxalate ◽  
Surface Protein Expression ◽  
Sirna Knockdown ◽  
Oxalate Transport

Most kidney stones are composed of calcium oxalate, and small increases in urine oxalate enhance the stone risk. The mammalian intestine plays a crucial role in oxalate homeostasis, and we had recently reported that Oxalobacter-derived factors stimulate oxalate transport by human intestinal Caco2-BBE (C2) cells through PKA activation. We therefore evaluated whether intestinal oxalate transport is directly regulated by activation of the PKA signaling pathway. To this end, PKA was activated with forskolin and IBMX (F/I). F/I significantly stimulated (3.7-fold) [14C]oxalate transport by C2 cells [≥49% of which is mediated by the oxalate transporter SLC26A6 (A6)], an effect completely blocked by the PKA inhibitor H89, indicating that it is PKA dependent. PKA stimulation of intestinal oxalate transport is not cell line specific, since F/I similarly stimulated oxalate transport by the human intestinal T84 cells. F/I significantly increased (2.5-fold) A6 surface protein expression by use of immunocytochemistry. Assessing [14C]oxalate transport as a function of increasing [14C]oxalate concentration in the flux medium showed that the observed stimulation is due to a F/I-induced increase (1.8-fold) in Vmax and reduction (2-fold) in Km. siRNA knockdown studies showed that significant components of the observed stimulation are mediated by A6 and SLC26A2 (A2). Besides enhancing A6 surface protein expression, it is also possible that the observed stimulation is due to PKA-induced enhanced A6 and/or A2 transport activity in view of the reduced Km. We conclude that PKA activation positively regulates oxalate transport by intestinal epithelial cells and that PKA agonists might therapeutically impact hyperoxalemia, hyperoxaluria, and related kidney stones.

scholarly journals Parsing apical oxalate exchange in Caco-2BBe1 monolayers: siRNA knockdown of SLC26A6 reveals the role and properties of PAT-1

2009 ◽  
Vol 297 (5) ◽  
pp. G918-G929 ◽  
Author(s):  
Robert W. Freel ◽  
Makoto Morozumi ◽  
Marguerite Hatch
Keyword(s):  
Ussing Chamber ◽  
Anion Transporter ◽  
Environment Control ◽  
Net Flux ◽  
Unidirectional Fluxes ◽  
The Difference ◽  
Sirna Knockdown ◽  
Interfering Rna ◽  
Oxalate Transport

The purpose of this investigation was to quantitate the contribution of the anion exchanger PAT-1 (putative anion transporter-1), encoded by SLC26A6, to oxalate transport in a model intestinal epithelium and to discern some characteristics of this exchanger expressed in its native environment. Control (Con) Caco-2 BBe1 monolayers, 6–8 days postseeding, were compared with those transfected with a small interfering RNA targeted to SLC26A6 (A6KD). Radiotracer and Ussing chamber techniques were used to determine the transepithelial unidirectional fluxes of Ox2−, Cl−, and SO42− whereas fluorometric/BCECF measurements of intracellular pH were used to assess HCO3− exchange. PAT-1 was functionally targeted to the apical membrane, and SLC26A6 knockdown reduced PAT-1 protein (>60%) and mRNA (>75%) expression in A6KD. No net flux of Ox2−, Cl−, or SO42− was detected in Con or A6KD monolayers, yet the unidirectional fluxes in A6KD were reduced 50, 35, and 15%, respectively. Cl−-dependent HCO3− efflux from A6KD was reduced 50% compared with Con. The difference between Con and A6KD properties represents that mediated solely by PAT-1, and by this approach we found that PAT-1-mediated oxalate influx and efflux are inhibited equally by mucosal DIDS (EC50 ∼5 μM) and that mucosal Cl− inhibits oxalate uptake with an EC50 < 20 mM. Transepithelial Cl− gradients supported large, DIDS-sensitive net absorptive or secretory fluxes of oxalate in a direction opposite that of the imposed Cl− gradient. The overall symmetry of PAT-1-mediated oxalate exchange suggests that vectorial oxalate transport observed in vivo is principally dependent on the magnitude and direction of counterion gradients.

Preparation, characterization, and in vivo evaluation of anti-inflammatory activities of selenium nanoparticles synthesized by Kluyveromyces lactis GG799

2021 ◽  
Author(s):  
Xiao fan Song ◽  
Lei Qiao ◽  
Shuqi Yan ◽  
Yue Chen ◽  
Xina Dou ◽  
...  
Keyword(s):  
Inflammatory Bowel Disease ◽  
Bowel Disease ◽  
Kluyveromyces Lactis ◽  
Selenium Nanoparticles ◽  
Human Diseases ◽  
In Vivo Evaluation ◽  
Inflammatory Bowel ◽  
Anti Inflammatory

Selenium (Se) as an essential micronutrient that has implications in human diseases, including inflammatory bowel disease (IBD), especially with respect to Se deficiencies. Recently, selenium nanoparticles (SeNPs) have attracted significant...

scholarly journals The food additive EDTA aggravates colitis and colon carcinogenesis in mouse models

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rayko Evstatiev ◽  
Adam Cervenka ◽  
Tina Austerlitz ◽  
Gunther Deim ◽  
Maximilian Baumgartner ◽  
...  
Keyword(s):  
Inflammatory Bowel Disease ◽  
Mouse Models ◽  
Bowel Disease ◽  
Intestinal Inflammation ◽  
Food Additives ◽  
Colorectal Carcinogenesis ◽  
Testing Procedures ◽  
Inflammatory Models ◽  
Inflammatory Bowel

AbstractInflammatory bowel disease is a group of conditions with rising incidence caused by genetic and environmental factors including diet. The chelator ethylenediaminetetraacetate (EDTA) is widely used by the food and pharmaceutical industry among numerous other applications, leading to a considerable environmental exposure. Numerous safety studies in healthy animals have revealed no relevant toxicity by EDTA. Here we show that, in the presence of intestinal inflammation, EDTA is surprisingly capable of massively exacerbating inflammation and even inducing colorectal carcinogenesis at doses that are presumed to be safe. This toxicity is evident in two biologically different mouse models of inflammatory bowel disease, the AOM/DSS and the IL10−/− model. The mechanism of this effect may be attributed to disruption of intercellular contacts as demonstrated by in vivo confocal endomicroscopy, electron microscopy and cell culture studies. Our findings add EDTA to the list of food additives that might be detrimental in the presence of intestinal inflammation, but the toxicity of which may have been missed by regulatory safety testing procedures that utilize only healthy models. We conclude that the current use of EDTA especially in food and pharmaceuticals should be reconsidered. Moreover, we suggest that intestinal inflammatory models should be implemented in the testing of food additives to account for the exposure of this primary organ to environmental and dietary stress.

scholarly journals Macrophage-derived EDA-A2 inhibits intestinal stem cells by targeting miR-494/EDA2R/β-catenin signaling in mice

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lele Song ◽  
Renxu Chang ◽  
Xia Sun ◽  
Liying Lu ◽  
Han Gao ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cross Talk ◽  
Intestinal Inflammation ◽  
Intestinal Stem Cells ◽  
Intestinal Stem Cell ◽  
Epithelial Barrier ◽  
Self Renewal ◽  
Epithelial Repair ◽  
Inflammatory Bowel

AbstractThe mucosa microenvironment is critical for intestinal stem cell self-renewal and reconstruction of the epithelial barrier in inflammatory bowel disease (IBD), where the mechanisms underlying cross-talk between intestinal crypts and the microenvironment remain unclear. Here, we firstly identified miR-494-3p as an important protector in colitis. miR-494-3p levels were decreased and negatively correlated with the severity in human IBD samples, as well as in colitis mice. In colitis crypts, a notable cytokine–cytokine receptor, miR-494-3p-targeted EDA2R and the ligand EDA-A2, suppressed colonic stemness and epithelial repair by inhibiting β-catenin/c-Myc. In differentiated IECs, miR-494-3p inhibits macrophage recruitment, M1 activation and EDA-A2 secretion by targeting IKKβ/NF-κB in colitis. A miR-494-3p agomir system notably ameliorated the severity of colonic colitis in vivo. Collectively, our findings uncover a miR-494-3p-mediated cross-talk mechanism by which macrophage-induced intestinal stem cell impairment aggravates intestinal inflammation.

scholarly journals Rediscovering histology: what is new in endoscopy for inflammatory bowel disease?

2021 ◽  
Vol 14 ◽  
pp. 175628482110056
Author(s):  
Virginia Solitano ◽  
Ferdinando D’Amico ◽  
Mariangela Allocca ◽  
Gionata Fiorino ◽  
Alessandra Zilli ◽  
...  
Keyword(s):  
Disease Activity ◽  
Narrow Band Imaging ◽  
Daily Practice ◽  
Cancer Surveillance ◽  
Special Focus ◽  
High Expectations ◽  
Endoscopic Techniques ◽  
Bowel Diseases ◽  
Inflammatory Bowel

The potential of endoscopic evaluation in the management of inflammatory bowel diseases (IBD) has undoubtedly grown over the last few years. When dealing with IBD patients, histological remission (HR) is now considered a desirable target along with symptomatic and endoscopic remission, due to its association with better long-term outcomes. Consequently, the ability of endoscopic techniques to reflect microscopic findings in vivo without having to collect biopsies has become of upmost importance. In this context, a more accurate evaluation of inflammatory disease activity and the detection of dysplasia represent two mainstay targets for IBD endoscopists. New diagnostic technologies have been developed, such as dye-less chromoendoscopy, endomicroscopy, and molecular imaging, but their real incorporation in daily practice is not yet well defined. Although dye-chromoendoscopy is still recommended as the gold standard approach in dysplasia surveillance, recent research questioned the superiority of this technique over new advanced dye-less modalities [narrow band imaging (NBI), Fuji intelligent color enhancement (FICE), i-scan, blue light imaging (BLI) and linked color imaging (LCI)]. The endoscopic armamentarium might also be enriched by new video capsule endoscopy for monitoring disease activity, and high expectations are placed on the application of artificial intelligence (AI) systems to reduce operator-subjectivity and inter-observer variability. The goal of this review is to provide an updated insight on contemporary knowledge regarding new endoscopic techniques and devices, with special focus on their role in the assessment of disease activity and colorectal cancer surveillance.

Anti-TNF-α Treatment Reduces the Baseline Procoagulant Imbalance of Patients With Inflammatory Bowel Diseases

2021 ◽  
Author(s):  
Armando Tripodi ◽  
Luisa Spina ◽  
Laura Francesca Pisani ◽  
Lidia Padovan ◽  
Flaminia Cavallaro ◽  
...  
Keyword(s):  
Inflammatory Bowel Diseases ◽  
Coagulation Factors ◽  
Infliximab Treatment ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Thrombosis Risk ◽  
Bowel Diseases ◽  
Inflammatory Bowel ◽  
Factor Α

Abstract Background Inflammatory bowel diseases (IBD) are characterized by an increased thrombosis risk of uncertain etiology. Coagulation derangement arising from inflammation may be a triggering factor. We hypothesized that strong inflammation inhibitors (eg, anti-tumor necrosis factor-α drugs) may affect coagulation. Methods Forty patients with IBD were compared with 57 control patients for coagulation factors and endogenous thrombin potential (ETP), the latter being the most sensitive marker of in vivo pro- and anticoagulation balance. We measured ETP in the presence and absence of thrombomodulin (the physiologic protein C [PC] activator). Coagulation at different timepoints was also assessed for 28 of these patients during infliximab treatment. Results The median ETP (nM thrombin × minutes) and range (minimum-maximum) were each higher in patients at baseline than in control patients in both the absence (2120 [1611-3041] vs 1865 [1270-2337]) and the presence (1453 [464-2522] vs 831 [104-1741]) of thrombomodulin. The ETP ratio (with/without thrombomodulin) was high at baseline (0.73 [0.21-0.90] vs 0.45 [0.07-0.85]). The ETP and ETP ratio declined during treatment and were significantly lower at the end than at baseline. Factor (F) VIII and fibrinogen, which were high at baseline, decreased during treatment and at the end were significantly lower than at baseline. The FVIII/PC ratio, which was high in patients at baseline, declined during treatment and at the end was lower than at baseline. C-reactive protein recorded at the end of treatment was lower than at baseline. Conclusions Patients with IBD have a procoagulant imbalance as shown by increased ETP at baseline. The ETP decreases during treatment with infliximab, which is related to decreased FVIII and FVIII/PC ratio. This effect is also related to the improvement of inflammation as shown by decreased fibrinogen and C-reactive protein.

Impact of β2 integrin deficiency on mouse natural killer cell development and function

Blood ◽  
2011 ◽  
Vol 117 (10) ◽  
pp. 2874-2882 ◽  
Author(s):  
Karine Crozat ◽  
Céline Eidenschenk ◽  
Baptiste N. Jaeger ◽  
Philippe Krebs ◽  
Sophie Guia ◽  
...  
Keyword(s):  
Cell Surface ◽  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
Surface Expression ◽  
Cell Maturation ◽  
Cell Surface Expression ◽  
Mcmv Infection ◽  
Β2 Integrin

Abstract Natural killer (NK) cells are innate immune cells that express members of the leukocyte β2 integrin family in humans and mice. These CD11/CD18 heterodimers play critical roles in leukocyte trafficking, immune synapse formation, and costimulation. The cell-surface expression of one of these integrins, CD11b/CD18, is also recognized as a major marker of mouse NK-cell maturation, but its function on NK cells has been largely ignored. Using N-ethyl-N-nitrosourea (ENU) mutagenesis, we generated a mouse carrying an A → T transverse mutation in the Itgb2 gene, resulting in a mutation that prevented the cell-surface expression of CD18 and its associated CD11a, CD11b, and CD11c proteins. We show that β2 integrin–deficient NK cells have a hyporesponsive phenotype in vitro, and present an alteration of their in vivo developmental program characterized by a selective accumulation of c-kit+ cells. NK-cell missing-self recognition was partially altered in vivo, whereas the early immune response to mouse cytomegalovirus (MCMV) infection occurred normally in CD18-deficient mice. Therefore, β2 integrins are required for optimal NK-cell maturation, but this deficiency is partial and can be bypassed during MCMV infection, highlighting the robustness of antiviral protective responses.

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