Exposure of Madin-Darby canine kidney (MDCK) cells to oxalate and calcium oxalate crystals activates nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase.

Objective: To investigate nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase activity in Madin-Darby canine kidney (MDCK) cells and the production of reactive oxygen species on exposure to oxalate (Ox) or calcium oxalate (CaOx) crystals.

Methods: Monolayers of confluent Madin-Darby canine kidney cells were exposed to 100, 300, 500 μmol, 1 mmol Ox or 33, 66, 132 μg/cm(2) CaOx crystals for 15 minutes, 30 minutes, 1 hour, 2 hours, or 3 hours. After specified periods of exposure to Ox and CaOx crystals, lactate dehydrogenase release, trypan blue exclusion, activation of NADPH oxidase, and superoxide production were determined using standard procedures.

Temporal changes in the expression of mRNA of NADPH oxidase subunits in renal epithelial cells exposed to oxalate or calcium oxalate crystals.

Background: Exposure of renal epithelial cells to oxalate (Ox) or calcium oxalate (CaOx) crystals leads to the production of reactive oxygen species and cell injury. We have hypothesized that Ox and CaOx crystals activate NADPH oxidase through upregulation of its various subunits.

Methods: Human renal epithelial-derived cell line, HK-2, was exposed to 100 μmol Ox or 66.

The effect of calcium on calcium oxalate monohydrate crystal-induced renal epithelial injury.

Since hypercalciuria is a common feature of idiopathic calcium oxalate (CaOx) nephrolithiasis, renal epithelial cells of stone patients are exposed to various crystals in the presence of high calcium. This study was performed to determine the effect of high calcium levels on CaOx crystal-induced cell injury. We exposed human renal epithelial cell line, HK2 in vitro to CaOx monohydrate crystals at a concentration of 133 microg/cm(2) for 1, 3, 6 or 12 h in the presence or absence of 5 or 10 mM/L calcium Ca(++).

Direct AFM measurements of adhesion forces between calcium oxalate monohydrate and kidney epithelial cells in the presence of Ca2+ and Mg2+ ions.

Adhesion forces between the calcium oxalate monohydrate (COM, whewellite) crystal and the layer of the epithelial kidney cells have been directly measured under buffer solutions by using atomic force microscope (AFM). Two renal epithelial lines, MDCK (a collecting duct line) and LLC-PK1 (a proximal tubular line), were used. All experiments were conducted in buffer solutions containing additional Ca(2+) and Mg(2+) ions in the various concentrations.

Apatite induced renal epithelial injury: insight into the pathogenesis of kidney stones.

Purpose: Kidney stone formation is associated with the deposition of hydroxyapatite as subepithelial plaques or tubular deposits in the renal papillae. We investigated the effect of renal epithelial exposure to hydroxyapatite crystals in vitro to develop an insight into the pathogenesis of kidney stones.

Materials And Methods: NRK52E cells (No.

Dietary oxalate and calcium oxalate nephrolithiasis.

Purpose: Patients with calcium oxalate kidney stones are advised to decrease the consumption of foods that contain oxalate. We hypothesized that a cutback in dietary oxalate would lead to a decrease in the urinary excretion of oxalate and decreased stone recurrence. We tested the hypothesis in an animal model of calcium oxalate nephrolithiasis.

Naturally produced crystals obtained from kidney stones are less injurious to renal tubular epithelial cells than synthetic crystals.

Objective: To determine the differences in cell responses to synthetic and biological crystals of calcium oxalate (CaOx) and brushite

Materials And Methods: Nephrolithiasis depends on crystal retention within the kidneys, often promoted by crystal attachment to the injured renal epithelium; studies often use various crystals that might be injurious to cells and cause the exposure of crystal binding molecules on cell surfaces, thus promoting crystal attachment and retention. The synthetic crystals used in these studies might be more injurious than the biological crystals naturally produced in the kidneys and that form kidney stones. We exposed the renal epithelial cell line NRK 52E in vitro to CaOx or brushite crystals at 67 or 133 microg/cm(2) for 3 or 6 h.

Adhesion force between calcium oxalate monohydrate crystal and kidney epithelial cells and possible relevance for kidney stone formation.

AFM interaction force measurements have been performed between calcium oxalate monohydrate crystal (COM) colloidal probes and monolayers of renal epithelial cells (on a polymer substrate) in artificial urine (AU) solutions. The adhesion force was measured for the COM/MDCK cell interaction, while no adhesion force was found for the COM/LLC-PK(1) cell interaction. Long-range repulsive forces for both lines of cells were measured in the range of 2-3 mum.

Reactive oxygen species mediated calcium oxalate crystal-induced expression of MCP-1 in HK-2 cells.

Under severe hyperoxaluric conditions calcium oxalate crystals often deposit in the renal interstitium and produce localized inflammation. We have proposed that renal epithelial cells exposed to CaOx crystals produce chemoattractants such as monocyte chemoattractant protein-1 (MCP-1). MCP-1 synthesis is mediated by reactive oxygen species (ROS).

Citrate and vitamin E blunt the shock wave-induced free radical surge in an in vitro cell culture model.

Free radical formation plays a major role in shock wave lithotripsy induced renal damage. Moreover, previous studies suggest that free radicals may also promote de novo calcium oxalate crystallization of previously damaged urothelium. Citrate is a known inhibitor of renal stone formation and has also been used as a free radical scavenger.

Oxalate induced expression of monocyte chemoattractant protein-1 (MCP-1) in HK-2 cells involves reactive oxygen species.

Oxalate is a toxic end product of metabolism largely because of its propensity to crystallize and form calcium oxalate, which is insoluble at physiologic pH and often deposits at very unfortunate sites, notably the kidneys. In the current study, we investigated the oxalate-induced injury and up-regulation of monocyte-chemoattractant protein-1 (MCP-1) in HK-2 cells, a proximal tubular epithelial cell line derived from normal human kidney. The cells were exposed to oxalate ions for different lengths of time.

Diphenyleneiodium (DPI) reduces oxalate ion- and calcium oxalate monohydrate and brushite crystal-induced upregulation of MCP-1 in NRK 52E cells.

Background: Our earlier studies have demonstrated upregulation of monocyte chemoattractant protein-1 (MCP-1) in NRK52E rat renal epithelial cells by exposure to oxalate (Ox) ions and crystals of calcium oxalate monohydrate (COM) or the brushite (Br) form of calcium phosphate. The upregulation was mediated by reactive oxygen species (ROS). This study was performed to investigate whether NADPH oxidase is involved in ROS production.

Citrate provides protection against oxalate and calcium oxalate crystal induced oxidative damage to renal epithelium.

Purpose: Oxalate and calcium oxalate (CaOx) crystals are injurious to renal epithelial cells. The injury is caused by the production of reactive oxygen species (ROS). Citrate is a well-known inhibitor of CaOx crystallization and as such it is one of the major therapeutic agents prescribed.

Calcium phosphate-induced renal epithelial injury and stone formation: involvement of reactive oxygen species.

Background: Crystal formation and retention are critical events for the formation of kidney stones. Oxalate and calcium oxalate (CaOx) crystals are injurious to renal epithelium, and membranes of injured cells promote crystal adherence and retention. Calcium phosphate (CaP) is the most common crystal in both urine and stones, most likely to form in the early segments of the nephron and can nucleate CaOx in a metastable solution.