RESUMEN
Ischemia-reperfusion injury (IRI) is a major cause of AKI, and previous studies established important roles for conventional CD4(+) T cells, natural killer T cells, and CD4(+)CD25(+)FoxP3(+) Tregs in AKI pathogenesis. We recently identified CD4(-)CD8(-) (double-negative; DN) T cells as an important subset of αß T cell receptor-positive cells residing in mouse kidney. However, little is known about the pathophysiologic functions of kidney DN T cells. In this study, we phenotypically and functionally characterized murine kidney DN T cells in the steady state and in response to IRI. Unlike CD4(+) and CD8(+) T cells, DN T cells in the steady state expressed high levels of CD69, CD28, and CD40L; differentially expressed IL-27 and IL-10 anti-inflammatory cytokines; spontaneously proliferated at a very high rate; and suppressed in vitro proliferation of activated CD4(+) T cells. Within the first 3-24 hours after IRI, kidney DN T cells expanded significantly and upregulated expression of IL-10. In adoptive transfer experiments, DN T cells significantly protected recipients from AKI by an IL-10-dependent mechanism. DN T cells also made up a large fraction of the T cell compartment in human kidneys. Our results indicate that DN T cells are an important subset of the resident αß(+) T cell population in the mammalian kidney and are early responders to AKI that have anti-inflammatory properties.
Asunto(s)
Lesión Renal Aguda/inmunología , Riñón/inmunología , Linfocitos T/fisiología , Animales , Antígenos CD4 , Antígenos CD8 , Humanos , Masculino , Ratones , Ratones Endogámicos C57BLRESUMEN
BACKGROUND: Transcription factor Nrf2 protects from experimental acute kidney injury (AKI) and is promising to limit progression in human chronic kidney disease (CKD) by upregulating multiple antioxidant genes. We recently demonstrated that deletion of Keap1, the endogenous inhibitor of Nrf2, in T lymphocytes significantly protects from AKI. In this study, we investigated the effect of Keap1 deletion on Nrf2 mediated antioxidant response in the renal tubular epithelial cells. METHODS: We deleted Keap1 exon 2 and 3 in the renal tubular epithelial cells by crossing Ksp-Cre mice with Keap1 floxed (Keap1 (f/f)) mice. Deletion of Keap1 gene in the kidney epithelial cells of Ksp-Keap1 (-/-) mice and its effect on Nrf2 target gene expression was performed using PCR and real-time PCR respectively. Histological evaluation was performed on H&E stained sections. Complete blood count, serum and urine analysis were performed to assess systemic effects of defective kidney development. Student's T test was used to determine statistical difference between the groups. RESULTS: Ksp-Cre resulted in the deletion of Keap1 exon 2 and 3 and subsequent upregulation of Nrf2 target genes, Nqo1, Gclm and Gclc in the kidney epithelial cells of Ksp-Keap1 (-/-) mice at baseline. Renal epithelial cell specific deletion of Keap1 in Ksp-Keap1 (-/-) mice caused marked renal pelvic expansion and significant compression of medullary parenchyma consistent with hydronephrosis in both (3 month-old) males and females. Kidneys from 6 month-old Ksp-Keap1 (-/-) mice showed progressive hydronephrosis. Hematological, biochemical and urinary analysis showed significantly higher red blood cell count (p = 0.04), hemoglobin (p = 0.01), hematocrit (p = 0.02), mean cell volume (p = 0.02) and mean cell hemoglobin concentration (p = 0.003) in Ksp-Keap1 (-/-) mice in comparison to Keap1 (f/f) mice. CONCLUSIONS: These unexpected findings demonstrate that Keap1 deletion in renal tubular epithelial cells results in an abnormal kidney development consistent with hydronephrosis and reveals a novel Keap1 mediated signaling pathway in renal development.
Asunto(s)
Epitelio/metabolismo , Hidronefrosis/genética , Hidronefrosis/metabolismo , Proteína 1 Asociada A ECH Tipo Kelch/deficiencia , Proteína 1 Asociada A ECH Tipo Kelch/genética , Riñón/metabolismo , Animales , Eliminación de Gen , Hidronefrosis/patología , Riñón/crecimiento & desarrollo , Riñón/patología , Masculino , Ratones , Ratones Noqueados , Ratones TransgénicosRESUMEN
T lymphocytes are established mediators of ischemia reperfusion (IR)-induced AKI, but traditional immune principles do not explain their mechanism of early action in the absence of alloantigen. Nrf2 is a transcription factor that is crucial for cytoprotective gene expression and is generally thought to have a key role in dampening IR-induced AKI through protective effects on epithelial cells. We proposed an alternative hypothesis that augmentation of Nrf2 in T cells is essential to mitigate oxidative stress during IR-induced AKI. We therefore generated mice with genetically amplified levels of Nrf2 specifically in T cells and examined the effect on antioxidant gene expression, T cell activation, cytokine production, and IR-induced AKI. T cell-specific augmentation of Nrf2 significantly increased baseline antioxidant gene expression. These mice had a high frequency of intrarenal CD25(+)Foxp3(+) regulatory T cells and decreased frequencies of CD11b(+)CD11c(+) and F4/80(+) cells. Intracellular levels of TNF-α, IFN-γ, and IL-17 were significantly lower in CD4(+) T cells with high Nrf2 expression. Mice with increased T cell expression of Nrf2 were significantly protected from functional and histologic consequences of AKI. Furthermore, adoptive transfer of high-Nrf2 T cells protected wild-type mice from IR injury and significantly improved their survival. These data demonstrate that T cell-specific activation of Nrf2 protects from IR-induced AKI, revealing a novel mechanism of tissue protection during acute injury responses.
Asunto(s)
Lesión Renal Aguda/inmunología , Lesión Renal Aguda/metabolismo , Factor 2 Relacionado con NF-E2/metabolismo , Linfocitos T Reguladores/fisiología , Lesión Renal Aguda/patología , Proteínas Adaptadoras Transductoras de Señales/genética , Traslado Adoptivo , Animales , Antioxidantes/metabolismo , Recuento de Linfocito CD4 , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Proteínas del Citoesqueleto/genética , Amplificación de Genes , Expresión Génica , Hemo-Oxigenasa 1/genética , Interferón gamma/metabolismo , Interleucina-17/metabolismo , Interleucina-4/metabolismo , Proteína 1 Asociada A ECH Tipo Kelch , Activación de Linfocitos/genética , Proteínas de la Membrana/genética , Ratones , Ratones Noqueados , Ratones Transgénicos , NAD(P)H Deshidrogenasa (Quinona)/genética , Factor 2 Relacionado con NF-E2/genética , Estrés Oxidativo , ARN Mensajero/metabolismo , Daño por Reperfusión/complicaciones , Daño por Reperfusión/inmunología , Daño por Reperfusión/patología , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
The pathophysiology of acute kidney injury (AKI) involves multiple and overlapping immunological, biochemical, and hemodynamic mechanisms that modulate the effects of both the initial insult and the subsequent repair. Limited but recent experimental data have revealed that the intestinal microbiota significantly affects outcomes in AKI. Additional evidence shows significant changes in the intestinal microbiota in chronic kidney disease patients and in experimental AKI. In this minireview, we discuss the current status of the effect of intestinal microbiota on kidney diseases, the immunomodulatory effects of intestinal microbiota, and the potential mechanisms by which microbiota can modify kidney diseases and vice versa. We also propose future studies to clarify the role of intestinal microbiota in kidney diseases and to explore how the modification of gut microbiota may be a potential therapeutic tool.