RESUMEN
Cystinuria is an incompletely dominant disorder characterized by defective urinary cystine reabsorption that results in the formation of cystine-based urinary stones. Current treatment options are limited in their effectiveness at preventing stone recurrence and are often poorly tolerated. We report that the nutritional supplement α-lipoic acid inhibits cystine stone formation in the Slc3a1-/- mouse model of cystinuria by increasing the solubility of urinary cystine. These findings identify a novel therapeutic strategy for the clinical treatment of cystinuria.
Asunto(s)
Cistina/efectos de los fármacos , Cistinuria/metabolismo , Riñón/efectos de los fármacos , Ácido Tióctico/farmacología , Urolitiasis/metabolismo , Sistemas de Transporte de Aminoácidos Básicos/genética , Sistemas de Transporte de Aminoácidos Neutros/genética , Animales , Cistina/metabolismo , Modelos Animales de Enfermedad , Riñón/diagnóstico por imagen , Riñón/metabolismo , Ratones , Ratones Noqueados , Solubilidad/efectos de los fármacos , Urolitiasis/diagnóstico por imagen , Microtomografía por Rayos XRESUMEN
BACKGROUND: Homozygous adenine phosphoribosyltransferase (APRT) deficiency is associated with 2,8-dihydroxyadenine (DHA) nephrolithiasis. Using whole kidney RNA from Aprt knockout mice, we previously showed that the renal deposition of DHA leads to changes in the expression of genes involved in tissue injury. To determine the cellular basis for these changes, we investigated gene expression in cultured human kidney (NHK-C) and African green monkey (BSC-1) epithelial cells exposed to DHA or calcium oxalate monohydrate (COM) crystals. METHODS: First-strand cDNAs, synthesized from mRNA isolated from treated and untreated cells, were hybridized to membrane-bound cDNA arrays containing 588 genes associated with various physiological and pathological processes. Changes in gene expression were confirmed by reverse transcription PCR. RESULTS: Twenty-seven percent of the array cDNAs were expressed in untreated NHK-C cells at varying levels relative to a housekeeping gene. The expression of three adhesion molecules (alpha-catenin, integrin alpha3, and integrin beta6) and platelet-derived growth factor B (PDGF-B) was elevated following exposure of NHK-C cells to DHA. Increased expression of the adhesion molecules was also observed in BSC-1 cells, but PDGF-B expression could not be detected. COM crystals also stimulated the expression of these four genes in NHK-C cells, but the expression profile was quantitatively different compared with DHA. CONCLUSIONS: These findings suggest that DHA crystals stimulate the expression of specific genes in kidney epithelial cells and that the pathways for DHA-induced cell injury may be similar to those for COM crystals. The induction of adhesion molecules and PDGF-B may affect cell-cell or cell-matrix interactions and/or alter the actin cytoskeleton. These alterations may ultimately contribute to crystal-induced renal injury.
Asunto(s)
Adenina/análogos & derivados , Adenina/farmacología , Proteínas del Citoesqueleto/genética , Integrina alfa3/genética , Cadenas beta de Integrinas/genética , Riñón/metabolismo , Proteínas Proto-Oncogénicas c-sis/genética , Adenina/química , Animales , Oxalato de Calcio/química , Oxalato de Calcio/farmacología , Línea Celular , Chlorocebus aethiops , Cristalización , ADN Complementario/genética , Perros , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Riñón/citología , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , alfa CateninaRESUMEN
The bacterial tripeptide formyl-Met-Leu-Phe (fMLP) induces the secretion of enzyme(s) with phospholipase A(2) (PLA(2)) activity from human neutrophils. We show that circulating human neutrophils express groups V and X sPLA(2) (GV and GX sPLA(2)) mRNA and contain GV and GX sPLA(2) proteins, whereas GIB, GIIA, GIID, GIIE, GIIF, GIII, and GXII sPLA(2)s are undetectable. GV sPLA(2) is a component of both azurophilic and specific granules, whereas GX sPLA(2) is confined to azurophilic granules. Exposure to fMLP or opsonized zymosan results in the release of GV but not GX sPLA(2) and most, if not all, of the PLA(2) activity in the extracellular fluid of fMLP-stimulated neutrophils is due to GV sPLA(2). GV sPLA(2) does not contribute to fMLP-stimulated leukotriene B(4) production but may support the anti-bacterial properties of the neutrophil, because 10-100 ng per ml concentrations of this enzyme lead to Gram-negative bacterial membrane phospholipid hydrolysis in the presence of human serum. By use of a recently described and specific inhibitor of cytosolic PLA(2)-alpha (group IV PLA(2)alpha), we show that this enzyme produces virtually all of the arachidonic acid used for the biosynthesis of leukotriene B(4) in fMLP- and opsonized zymosan-stimulated neutrophils, the major eicosanoid produced by these pro-inflammatory cells.