RESUMO
The ICR-derived glomerulonephritis (ICGN) mouse is an appropriate model for anemia associated with chronic renal disorder (CRD). Insufficient renal production of erythropoietin (EPO) induces the anemia associated with CRD. EPO mRNA is expressed in both kidneys and liver of progressing-stage ICGN mice. Hypoxic stimulation induced the EPO mRNA expression in the liver as well as in the kidneys of ICGN mice. The localization of EPO-producing cells in the liver remains controversial. Present study using an amplified in situ hybridization technique identified that nonparenchymal cells were the source of hepatic EPO production in ICGN mice under both normoxia and hypoxia.
Assuntos
Células Precursoras Eritroides/metabolismo , Eritropoetina/metabolismo , Glomerulonefrite/metabolismo , Rim/citologia , Fígado/citologia , Animais , Primers do DNA , Hibridização In Situ , Rim/metabolismo , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Lysyl oxidase (LOX), an extracellular enzyme, plays a key role in the post-translational modification of collagens and elastin, catalyzing inter- and intra-crosslinking reactions. Because the crosslinked extracellular matrices (ECMs) are highly resistant to degradative enzymes, it is considered that the over-expression of LOX may cause severe fibrotic degeneration. In the present study, we addressed the role of LOX-mediated crosslinking in chronic renal tubulointerstitial fibrosis using an animal model of hereditary nephrotic syndrome, the Institute of Cancer Research (ICR)-derived glomerulonephritis (ICGN) mouse. Ribonuclease protection assay (RPA) revealed that LOX mRNA expression was up-regulated in the kidneys of ICGN mice as compared with control ICR mice. High-level expression of LOX and transforming growth factor (TGF)-beta1 (an up-regulator of LOX) mRNA was detected in tubular epithelial cells of ICGN mouse kidneys by in situ hybridization. Type-I and -III collagens, major substrates for LOX, were accumulated in tubulointerstitium of ICGN mouse kidneys. The present findings imply that TGF-beta1 up-regulates the production of LOX in tubular epithelial cells of ICGN mouse kidneys, and the excessive LOX acts on interstitial collagens and catalyzes crosslinking reactions. As a result, the highly crosslinked collagens induce an irreversible progression of chronic renal tubulointerstitial fibrosis in the kidneys of ICGN mice.
Assuntos
Glomerulonefrite/metabolismo , Rim/enzimologia , Síndrome Nefrótica/metabolismo , Proteína-Lisina 6-Oxidase/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Animais , Células Cultivadas , Doença Crônica , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Feminino , Fibrose/enzimologia , Fibrose/patologia , Glomerulonefrite/genética , Humanos , Hibridização In Situ , Rim/patologia , Túbulos Renais/efeitos dos fármacos , Túbulos Renais/metabolismo , Túbulos Renais/patologia , Masculino , Camundongos , Camundongos Endogâmicos ICR , Síndrome Nefrótica/patologia , Proteína-Lisina 6-Oxidase/genética , RNA Mensageiro/análise , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/farmacologia , Fator de Crescimento Transformador beta1 , Regulação para CimaRESUMO
Anemia is a major secondary symptom in chronic renal disorder (CRD), but the precise cause of insufficient production of erythropoietin (EPO) remains unclear owing to the controversial localization of EPO-producing cells in the kidneys. The ICR-derived glomerulonephritis (ICGN) mouse, a new hereditary nephrotic mouse, is an appropriate model of anemia associated with CRD. By using an amplified in situ hybridization technique, we detected and counted the renal EPO-producing cells under both normoxic and hypoxic conditions. The expression levels of renal EPO mRNA were quantified and oxygen gradients were also assessed immunohistochemically. Amplified in situ hybridization clarified that EPO-producing cells were peritubular interstitial cells in the middle region of renal cortex in both ICR and ICGN mice. Hypoxia (7% O2) induced low oxygen tension in proximal tubular epithelial cells of renal cortex, and increased the expression of EPO mRNA and the number of EPO-producing cells in both ICR and ICGN mice. However, hypoxia did not increase the serum EPO levels in ICGN mice. The ICGN mouse is a good model for anemia associated with CRD, and the suppression of EPO protein production in the renal EPO-producing cells is considered to be a potential cause of anemia associated with CRD.
Assuntos
Anemia/fisiopatologia , Eritropoetina/metabolismo , Falência Renal Crônica/complicações , Rim/citologia , Rim/fisiopatologia , RNA Mensageiro/metabolismo , Análise de Variância , Anemia/etiologia , Animais , Eritropoetina/genética , Hipóxia/metabolismo , Imuno-Histoquímica , Hibridização In Situ , Camundongos , Camundongos Endogâmicos ICRRESUMO
The ICR-derived glomerulonephritis (ICGN) mouse, a novel inbred mouse strain with a hereditary nephrotic syndrome, develops severe anemia associated with chronic renal failure. To reveal the pathogenic mechanism of anemia in ICGN mice, we subcutaneously administered recombinant human erythropoietin (rhEPO; 5 IU/mouse/day) or saline for 5 days to ICGN mice. In terminal-stage ICGN mice with severe anemia, rhEPO significantly increased hematocrit (Ht), red blood cells (RBC) and hemoglobin levels. Endogenous EPO levels in peripheral blood were reduced by rhEPO injection. No histopathological changes in bone marrow and kidneys were induced by rhEPO injection. Insufficiency of EPO may cause anemia in ICGN mice.