Koki Fujikawa

Splenectomy protects the kidneys against ischemic reperfusion injury in the rat

BACKGROUND Ischemic reperfusion (I/R) injury of the kidney is closely associated with delayed graft function, increased acute rejection, and late allograft dysfunction. Splenectomy reduced hepatic I/R injury by inhibiting leukocyte infiltration in the liver, release of TNF-α, cell apoptosis, and expression of caspase-3. Thus, we investigated the effects of splenectomy on renal I/R injury in the rat. METHODS Male Wistar rats were assigned to four groups: sham operation (sham group), sham operation+splenectomy (sham+SPLN group), right nephrectomy followed by clamping the left renal pedicle for 30min (I/R 30 group), and I/R 30+splenectomy (I/R 30+SPLN group). Renal function was determined by measuring the concentration of blood urea nitrogen (BUN) and serum creatinine (S-Cr). The serum level of tumor necrosis factor-α (TNF-α) was measured as the marker for inflammation. Left kidneys were obtained 24h after reperfusion. TUNEL assay was assessed for cell apoptosis. Spleens were obtained immediately (0-h group) and 3h after reperfusion (3-h group). The removed spleens were histologically evaluated. RESULTS The BUN and S-Cr levels were significantly lower in the I/R 30+SPLN group than in the I/R 30 group (p<0.05 for both). Apoptotic cells were significantly lower in the I/R 30+SPLN group than in the I/R 30 group. The serum level of TNF-α, which was increased after I/R, was significantly lower in the I/R 30+SPLN group than in the I/R 30 group (p<0.05). Spleen weights were significantly lower in the 3-h group than in the 0-h group (p<0.05). CONCLUSION These results suggest that splenectomy reduces renal I/R injury, and this effect may occur by an anti-inflammatory pathway and inhibition of cell apoptosis.

Anti-TNF-α Agent Infliximab and Splenectomy Are Protective Against Renal Ischemia-Reperfusion Injury.

Background Renal ischemia-reperfusion (I/R) injury is associated with delayed graft function and results in poor long-term graft survival. We previously showed that splenectomy (SPLN) protects the kidney from I/R injury and reduces serum TNF-&agr; levels. Herein, we further investigated the effects of SPLN on inflammatory responses and tissue injury in renal I/R by examining the expression of major inflammatory cytokines and heat shock protein 70 (HSP70). Because it was shown previously that the anti–TNF-&agr; agent infliximab (IFX) attenuated renal I/R injury, we also investigated whether IFX administration mimics the effects of SPLN. Methods The left renal pedicles of adult male Wistar rats were clamped for 45 minutes and then reperfused for 24 hours; right nephrectomy and SPLN were performed immediately. A separate cohort was administered IFX 1 hour before surgery in lieu of SPLN. Results Serum creatinine and blood urea nitrogen levels were markedly elevated by I/R injury; these increases were significantly reversed by IFX. Furthermore, IFX inhibited the induction of inflammatory cytokines and HSP70 during renal I/R injury. Time-dependent profiles revealed that the expression of inflammatory cytokines was elevated immediately after I/R, whereas levels of HSP70, serum creatinine, and blood urea nitrogen began to rise 3 hours postreperfusion. Macrophages/monocytes were significantly increased in I/R-injured kidneys, but not in those administered IFX. The outcomes of SPLN mirrored those of IFX administration. Conclusions Splenectomy and TNF-&agr; inhibition both protect the kidney from I/R injury by reducing the accumulation of renal macrophages/monocytes and induction of major inflammatory cytokines.

Expression of mRNA for growth factors and extracellular matrix proteins after injury to cultured peritoneal cells: does the healing process contribute to peritoneal ultrastructural alteration?

The purpose of this study was to investigate the possibility that healing processes following repeated injury by nonphysiological dialysate play a significant role in the pathogenesis of peritoneal ultrastructural alteration, mediated by the production of growth factors and extracellular matrix proteins (ECM). To test a possible mechanism for peritoneal membrane alteration, we investigated whether chemically injured peritoneal mesothelial cells and fibroblasts upregulate their production of growth factors and ECM as a consequence of the healing process. Using 1 N NaOH, circular wounds of uniform surface area were made in monolayers of subconfluent rat peritoneal mesothelial cells (RPMC) and peritoneal fibroblasts (RPFB). At 0, 24, and 72 h after wounding, changes in mRNA expression of transforming growth factor-beta 1 (TGF-Β1), b-FGF, HGF, VEGF, and FN were semiquantified by reverse transcription-polymerase chain reaction. Nonwounded monolayers of RPMC and RPFB were used as controls with mRNA expression being determined at the same times. For RPMC, TGF-Β1, HGF, b-FGF, and FN mRNA gradually increased up to 72 h postwounding to 1.5-fold, 1.6-fold, 1.3-fold, and 2.1-fold of the control levels, respectively. A significant increase was only observed for TGF-Β1, while VEGF showed the least change with time. For RPFB, HGF, b-FGF, VEGF, and FN mRNA expression were slightly suppressed compared to control levels up to 72 h postwounding. TGF-Β1, however, increased markedly above control expression levels by the end of the wound healing process. The production of profibrotic growth factors by mesothelial cells in response to injury may represent a mechanism whereby fibroblast activation, resulting in fibroblast hyperplasia and excessive extracellular matrix accumulation, culminates in alteration of the peritoneal membrane ultrastructure.

Effects of tacrolimus on rat thymic epithelial cells.

FK506 is an immunosuppressive agent that was discovered in Japan. Many experiments on organ transplantation have shown the prolongation of allograft survival in animals by treatment with FK506. Previous studies have also shown that FK506 has a remarkable immunosuppressive effect and improves the outcome of liver transplantation. We recently analyzed the effect of FK506 on thymocyte differentiation by the immunoperoxidase technique and flow cytometry using monoclonal antibodies (MoAbs) for thymus and T-cell surface antigens, and we found a reduction of major histocompatibility complex (MHC) class II antigen expression on thymic epithelial cells. Our results have suggested that FK506 inhibited thymocyte differentiation in rats by not only directly but also by indirectly acting on thymic epithelial cells. In the present study, we investigated the effect of FK506 on rat thymic epithelial cells by immunohistochemistry using various MoAbs.