Clinical Significance of Monitoring Circulating CD4+CD25+ Regulatory T Cells in Kidney Transplantation during the Early Posttransplant Period

The CD4+CD25+ T regulatory cells (Tregs) play an important role in immune tolerance in experimental transplantation but the clinical significance of circulating Tregs in the peripheral blood is undetermined. In 50 kidney transplant (KT) recipients, 29 healthy controls and 32 liver transplant (LT) recipients, the frequency of Tregs was measured with flow cytometry before and after transplantation. In the KT recipients, IL-10 secretion was measured with an enzyme-linked immunospot (ELISPOT) assay. The median frequency of circulating Tregs before KT was similar to that in healthy controls but significantly lower than that in LT patients before transplantation. The frequency of Tregs was significantly decreased in patients with subclinical acute rejection compared with those without subclinical acute rejection. Calcineurin inhibitors (CNIs) and anti-CD25 antibody decreased the frequency of Tregs but mTOR inhibitor did not. The frequency of donor-specific IL-10 secreting cells did not correlate with the number of Tregs. The frequency of circulating Tregs in KT recipients is strongly affected by CNIs and anti-CD25 antibody, and a low frequency of Tregs is associated with subclinical acute rejection during the early posttransplant period.

Induction of Acute Cyclosporine Nephrotoxicity in Pig / 대한이식학회지

PURPOSE: Pigs are promising donor species for xenotransplantation. This study was performed to examine acute cyclosporine (CsA) nephrotoxicity in a pig model. METHODS: Adult pigs were treated daily for 1 week with vehicle (VH), or 7.5 mg/kg (CsA7.5), 15 mg/kg (CsA15), and 30 mg/kg (CsA30) CsA. The renal function, electrolyte levels, whole- blood CsA levels, and histopathological results (vacuolization and tubulointerstitial fibrosis) were compared among the different treatment groups. RESULTS: After 1 week of treatment, it was found that CsA induced characteristic lesions that were remarkably similar to those of chronic CsA nephropathy in humans. Compared with the results obtained for the VH group, CsA reduced renal function and yielded poor histopathological results. With an increase in the CsA concentration, the renal function and histological parameters worsened in a dose-dependent manner. CONCLUSION: The study showed that CsA dose-dependently induced renal injury in a pig model. These results provide basic data to estimate or prevent the adverse renal effects of immunosuppressants during porcine xenotransplantation in the future.

Immunocytochemical Study of Calbindin D(28k) Positive Cells in the Developing Rat Kidney / 대한해부학회지

Calbindin D(28k),a calcium binding protein,is found in various tissues,including some cells in the distal nephron.It plays an important role in the regulation of calcium reabsorption. We previously reported the expression of calbindin D(28k) in adult rat kidney.However,the exact time of expression during differentiation in the embryonic kidney is not known.During development,intercalated cells are deleted from the medullary collecting duct by two distinct mechanisms.However,the reason for the different modes of cell death is not known.As calbindin is reported to protect cells against apoptosis,we examined the expression of calbindin D(28k) in the developing rat kidney.Kidneys from 16-,17-,18-and 20-day-old fetuses and 1-,3-,5-,7-,14-and 21-day-old pups and adult Sprague awley rats were processed for immunohistochemistry using a monoclonal antibody against calbindin D(28k) .Intercalated cells were identified by immunostaining for H+ -ATPase and by electron microscopy.Calbindin D(28k) immunoreactivity first appeared in subpopulations of cells in the connecting tubule and medullary collecting duct in the 17-day-old fetus.In the connecting tubule,calbindin D(28k) was expressed only in H+ -ATPase negative connecting tubule cells,and there was no labeling of intercalated cells.In the medullary collecting duct,calbindin D(28k) immunostaining was observed in a few cells with apical H+ -ATPase,characteristic of type A intercalated cells.The numbers of calbindin D(28k) -positive type A intercalated cells increased from day 18 of gestation.In contrast,there was little or no calbindin D(28k) immunoreactivity in the type B intercalated cells or principal cells.During the first two weeks after birth,calbindin D(28k) -positive type A intercalated cells were lost from the terminal part of the medullary collecting duct by simple extrusion. After two weeks,calbindin D(28k) immunostaining decreased in the type A intercalated cells throughout the medullary collecting duct.However,the immunoreactivity of calbindin D(28k) in the cortical collecting duct was increased in some of the type A intercalated cells and the adult pattern was observed in 21-day-old pups.Thus,we propose that the different expression of calbindin D(28k) in type A and type B intercalated cells may be responsible-at least partly-for the different modes of cell death demonstrated in these cells during kidney development.

Ultrastructural Localization of the Ammonia Transporter Protein, RhCG, in Rat Kidney Collecting Duct / 대한해부학회지

Ammonia excretion in the renal collecting duct is critical in the regulation of the acid-base homeostasis. A novel family of ammonium transporter protein, Rh C Glycoprotein (RhCG) was recently identified in the mouse and rat kidney collecting duct. The purpose of this study was to examine the ultrastructural localization of RhCG in the collecting duct. Rat kidneys were processed for light and electron microscope immunocytochemistry using anti-RhCG rabbit polyclonal antibody. Strong RhCG immunolabeling was observed in the apical domain of AE1-positive type A intercalated cells in the collecting duct. Transmission electron microscopy revealed that a high level of RhCG was expressed in the apical plasma membrane and in subapical vesicles of type A intercalated cell. Interestingly, type A cells also expressed weak immunolabel in the basolateral plasma membrane. Type B cells had weak apical plasma membrane and subapical vesicle immunolabel, and very weak basolateral plasma membrane immunolabel. Principal cells had very weak apical plasma membrane immunolabel without detectable subapical or basolateral immunolabel These results demonstrate that RhCG is mainly expressed in the apical plasma membrane and in subapical vesicles of acid-secreting type A cells and may mediate ammonia excretion in the collecting duct.

Expression of an Anion Exchanger Pendrin in Human Kidney / 대한해부학회지

It has been reported that new apical anion exchanger perndrin, encoded by the pendred syndrome (PDS/pds, Slc26A4) gene, was expressed in the AE1-negative intercalated cells of rat and mouse kidneys. The purpose of this study was performed that expression of pendrin in the subtypes of intercalated cells in human kidney. The normal human renal tissues obtained from nephrotomized kidneys for renal cell carcinoma were fixed in periodate-lysine-paraformalde-hyde, and processed for immunohistochemistry. Subtypes of intercalated cells were identified by using antibodies for H(+)-ATPase and AE1, and connecting tubule cells and principal cells of collecting duct were identified using antibodies for calbindin D28K and AQP2, respectively. In human kidney, pendrin was expressed in the apical domain of AE1-negative intercalated cells including type B cells with diffuse and/or basolateal H(+)-ATPase, non A-non B (non -A/B) type intercalated cells with apical H(+)-ATPase and bipolar type of intercalated cells with apical and basolateral H(+)-ATPase. The AQP2-positive principal cells of cortical collecting duct were also had apical pendrin immunoreactivity. However, there was no pendrin immunoreactivity in AE1-positive type A intercalated cells, calbindin D28K-positive connecting tubule cells, and AQP2-positive medullary collecting duct. These results suggest that pendrin is an apical anion exchanger not only in the AE1-negative intercalated cells (type B, non-A/B and bipolar cells) but also in the principal cells of cortical collecting duct, and has an essential role in HCO3-secretion in human kidney.

Expression of Osteopontin in Chronic Potassium Depletion-induced Renal Injury / 대한해부학회지

Osteopontin (OPN), a potent chemoattractant for the monocyte/macrophage infiltration, is highly upregulated in the renal tubular epithelium during various pathologic conditions associated with tubulointerstitial injury. The purpose of this study was to establish the distribution and localization of OPN in the tubulointerstitial injury induced by chronic potassium (K+) deprivation in the rat kidney. Sprague-Dawley rats were fed either a normal or a K+ -deficient diet for 2 weeks. Kidney tissues were preserved by in vivo perfusion with paraformaldehyde-lysine-periodate (PLP) and processed for light and electron microscope immunocytochemistry using monoclonal antibodies to OPN. K+ -depleted kidneys showed tubulointerstitial injury with renal hypertrophy, monocyte/macrophage infiltration, interstitial fibrosis, and OPN overexpression. OPN immunoreactivity was observed only in the descending thin limb (DTL) and the papillary surface epithelium (PSE) in the control kidney. However, the OPN labeling was observed not only in DTL and PSE but also in the thick ascending limb (TAL) in the K+ -depleted kidney. Electron microscopy revealed that OPN induced in the TAL cells was not located in the basal plasma membrane, but in the Golgi apparatus and in subapical cytoplasmic vesicles. There was no OPN expression in the epithelium of the collecting ducts, which showed marked morphological damages with mononuclear cell infiltration. These results demonstrate that chronic K+ -deprivation causes renal injury with the increased OPN expression in tubular epithelial cells. However, the localization of the induced OPN suggests other roles rather than a chemoattractant function in this renal injury model.