Renoprotective effects of laxative linaclotide: Inhibition of acute kidney injury and fibrosis in a rat model of renal ischemia-reperfusion.

Ischemia-reperfusion (I/R) leads to tissue damage in transplanted kidneys, resulting in acute kidney injury (AKI) and chronic graft dysfunction, which critically compromises transplant outcomes, such as graft loss. Linaclotide, a guanylate cyclase C agonist clinically approved as a laxative, has recently been identified to exhibit renoprotective effects in a chronic kidney disease (CKD) model. This study evaluates the therapeutic effects of linaclotide on AKI triggered by I/R in a rat model with an initial comparison with other laxatives. Here, we show that linaclotide administration resulted in substantial reduction in serum creatinine levels, reflective of enhanced renal function. Histological examination revealed diminished tubular damage, and Sirius Red staining confirmed less collagen deposition, collectively indicating preserved structural integrity and mitigation of fibrosis. Further analysis demonstrated lowered expression of TGF-ß and associated fibrotic markers, α-SMA, MMP2, and TIMP1, implicating the downregulation of the fibrogenic TGF-ß pathway by linaclotide. Furthermore, one day after I/R insult, linaclotide profoundly diminished macrophage infiltration and suppressed critical pro-inflammatory cytokines such as TNF, IL-1ß, and IL-6, signifying its potential to disrupt initial inflammatory mechanisms integral to AKI pathology. These findings suggest that linaclotide, with its established safety profile, could extend its benefits beyond gastrointestinal issues and potentially serve as a therapeutic intervention for organ transplantation. Additionally, it could provide immediate and practical insights into selecting laxatives for managing patients with AKI or CKD, regardless of the cause, and for those receiving dialysis or transplant therapy.

Risks and benefits of transurethral resection of the bladder tumor using photodynamic diagnosis with oral 5-aminolevulinic acid hydrochloride according to age and history of recurrence in patients with non-muscle invasive bladder cancer.

BACKGROUND: Patient selection for transurethral resection of the bladder tumor using photodynamic diagnosis (PDD-TURBT) with oral 5-aminolevulinic acid (5-ALA) hydrochloride for non-muscle-invasive bladder cancer (NMIBC) is still unclear as to the best balance of risks (adverse events including hypotension) and benefits (reduction of intravesical recurrence). METHODS: This single-center retrospective study between April 2013 and March 2022, compared the intravesical recurrence-free survival between patients who underwent PDD-TURBT and WL-TURBT using propensity score matching. RESULTS: A total of 222 patients who underwent PDD-TURBT and 177 patients who underwent WL-TURBT for NMIBC were included. Propensity score matching was used to compare intravesical recurrence-free survival in 119 NMIBC patients in the both treatment groups. The intravesical recurrence-free survival within 500 days was significantly higher in the PDD-TURBT group than in the WL-TURBT group (P = 0.039; hazard ratio [HR] 0.48 [0.23-0.98]). Subgroup analysis showed that PDD-TURBT contributed to the reduction of short-term intravesical recurrence in patients aged < 75 years (P = 0.02; HR 0.22 [0.06-0.79]) and primary disease (P = 0.038; HR 0.35 [0.13-0.94]). Hypotension with a systolic blood pressure of < 80 mmHg was observed in 79 patients (35.6%) during PDD-TURBT surgery. In particular, age ≥75 years and general anesthesia were independent prognostic factors for predicting intraoperative hypotension. CONCLUSIONS: PDD-TURBT reduced short-term intravesical recurrence in NMIBC, whereas a higher frequency of hypotension was found in patients aged ≥ 75 years. These results suggest that the risks and benefits of PDD-TURBT are well balanced in younger patients (< 75 years) and those with primary disease.

Association between amorphous calcium-phosphate ratios in circulating calciprotein particles and prognostic biomarkers in hemodialysis patients.

Calciprotein particles (CPPs) are circulating colloidal mineral-protein complexes containing crystalline and/or non-crystalline (amorphous) calcium-phosphate (CaPi). Serum CPP levels correlate with vascular stiffness and calcification in patients with chronic kidney disease (CKD). In vitro studies showed that CPPs containing crystalline CaPi were more arteriosclerogenic and inflammogenic than CPPs without containing crystalline CaPi. Thus, we hypothesized that not only the quantity but also the quality of CPPs (the phase of CaPi) might affect clinical outcomes. To test this hypothesis, we quantified amorphous CaPi ratio defined as the ratio of the amorphous CaPi amount to the total CaPi amount in serum CPPs from 183 hemodialysis patients and explored its possible correlation with serum parameters associated with prognosis of hemodialysis patients. Multivariate analysis revealed that the amorphous CaPi ratio correlated positively with hemoglobin and negatively with fibroblast growth factor-21 (FGF21), which remained significant after adjusting for the total CaPi amount. Because low hemoglobin and high FGF21 are associated with increased mortality, the present study warrants further studies to determine whether low amorphous CaPi ratio in circulating CPPs may be associated with poor prognosis in hemodialysis patients.

Mucin-producing urothelial-type adenocarcinoma of the prostate diagnosed after robot-assisted radical prostatectomy.

INTRODUCTION: Mucin-producing adenocarcinoma of the prostate is a rare disease that includes prostate adenocarcinoma with mucus production, secondary adenocarcinoma from the bladder or colorectum, and adenocarcinoma from the urothelium of the prostatic urethra. We describe prostate-specific antigen-negative mucin-producing urothelial-type adenocarcinoma of the prostate. CASE PRESENTATION: The patient had urinary retention and a serum prostate-specific antigen level of 0.74 ng/mL. Computed tomography and magnetic resonance imaging revealed a prostate tumor with a mucous component. We diagnosed adenocarcinoma by prostate biopsy and subsequently performed robot-assisted radical prostatectomy. Mucin-producing urothelial-type adenocarcinoma of the prostate was diagnosed by pathological examinations. Lung metastasis, developing within 3 months after surgery, was treated using chemotherapy. CONCLUSION: Endocrine therapy is ineffective for mucin-producing urothelial-type adenocarcinoma of the prostate. Mucin-producing urothelial-type adenocarcinoma of the prostate diagnosis requires pathological and immunohistochemical analyses. It is important to surgically remove the primary lesion, and robot-assisted radical prostatectomy may provide an effective approach. Multimodal therapy is essential to treat for mucin-producing urothelial-type adenocarcinoma of the prostate.

Endoscopic laser treatment for urine leakage caused by an isolated calyx after robot-assisted partial nephrectomy.

INTRODUCTION: An isolated calyx is a rare complication in which the renal calyx and pelvis are disconnected. The treatment is often complicated. CASE PRESENTATION: An 81-year-old man underwent robot-assisted partial nephrectomy for the treatment of renal cell carcinoma (cT1bN0M0). Postoperatively, urine leakage was observed and did not improve with conservative measures. Retrograde pyelography and computed tomography revealed that urine leakage originated from the isolated calyx caused by infundibular stenosis. Endoscopic treatment via the transurethral approach was selected to preserve renal function. Ureteroscopy showed that the upper calyx was completely obstructed by the sutures. Therefore, we cut the suture thread using laser, and a ureteral stent was placed in the upper renal calyx. Fluid drainage immediately disappeared after the procedure, and the patient did not lose renal function. CONCLUSION: Endoscopic management might be an option for isolated calyx after robot-assisted partial nephrectomy.

Receptor activator of the NFκB ligand system protects renal function during experimental renal ischemia-reperfusion in mice.

Renal ischemia-reperfusion (I/R) injury is closely associated with delayed graft function and poor long-term graft survival following transplantation. Various pathophysiologies can cause the deterioration of renal function; however, the immune system plays important roles in promoting and protecting renal tissues. Receptor activator of NFκB ligand (RANKL) is a member of the TNF superfamily and is produced by bone-forming osteoblasts; the receptor for RANKL is called RANK. In bone biology, RANKL-RANK signaling has been extensively studied, but its roles in the immune system are still obscure. We investigated the role of the RANK system in I/R injury of the kidney using an experimental mouse I/R model. The left renal pedicles of 10-week-old male mice were clamped for 60 min, and reperfusion and right nephrectomy were simultaneously performed. Separate groups were administered an anti-RANKL antibody and recombinant RANKL (rRANKL) 24 h prior to I/R. After reperfusion for a set period of time, the serum creatinine level was measured, and the left kidney was removed for histological examination and western blotting to evaluate the expression and localization of RANK-associated molecules and cytokines. The serum creatinine levels were significantly elevated after I/R injury. A time-dependent increase in RANKL was observed up to 24 h, whereas RANK was induced for 12 h after reperfusion. RANK was expressed in infiltrating inflammatory cells, which were positive for CD68, a marker of monocytes/macrophages. The pre-treatment with the anti-RANKL antibody significantly impaired renal function and increased the induction of inflammatory cytokines (TNFα and IL-6), Toll-like receptor (TLR4) and MyD88 (all p < .05) compared to the levels in the I/R group. However, rRANKL significantly improved renal function and decreased the levels of inflammatory cytokines (TNFα and IL-6), TLR4 and MyD88 (p < .05) compared to those in the I/R group. The present study is the first to evaluate the role of the RANK system in renal I/R injury. RANKL-RANK signaling affects macrophage function and results in the downregulation of TLR4 and reduction in TNFα and IL-6, leading to improved renal function following I/R injury.

The effect of lanthanum carbonate on calciprotein particles in hemodialysis patients.

BACKGROUND: Aggregation of solid-phase calcium-phosphate and fetuin-A form nanoparticles called calciprotein particles (CPP). Serum CPP levels are increased in CKD patients and correlated with vascular stiffness and calcification. In this study, we evaluated effects of lanthanum carbonate (LC) and calcium carbonate (CC) on serum CPP levels in hemodialysis (HD) patients. METHODS: Twenty-four (24) HD patients (50% men, age; 68 ± 12 years, dialysis period; 6.2 ± 4.8 years, Kt/v; 1.74 ± 0.34) were treated with CC during 0-8 weeks and then switched to LC during 9-16 weeks. Blood samples were obtained at 0, 8, 16 weeks. Serum CPP levels (TCPP) were measured by the gel-filtration method. Low-density CPP (LCPP) levels were determined by centrifuging the serum samples at 16,000 g for 2 h and measuring CPP levels in the supernatant. The difference between TCPP and LCPP was defined as the high-density CPP (HCPP) level. We evaluated association of TCPP, LCPP, and HCPP with serum calcium (Ca), phosphorus (P), intact PTH, FGF23, Klotho, fetuin-A, aortic calcification index (ACI), LDL cholesterol, and hs-CRP. RESULTS: TCPP and LCPP levels were significantly decreased after switching CC to LC, whereas Ca and P levels were not changed. HCPP levels were below the lower limit quantification in all patients. The changes in P, Ca × P, LDL cholesterol, but not ACI and the changes in hs-CRP, were correlated with the change in TCPP levels. CONCLUSION: The TCPP levels were significantly decreased after switching CC to LC. Non-calcium-containing phosphate binders may be preferable for lowering CPP levels.

Plasma Pentosidine and Its Association with Mortality in Patients with Chronic Kidney Disease.

BACKGROUND: Circulating advanced glycated end-products (AGEs) including pentosidine accumulating in chronic kidney disease (CKD) patients due to retention and increased formation are thought to contribute to cardiovascular disease (CVD). Here we evaluated factors linked to increased plasma pentosidine and its association with mortality in patients with different stages of CKD and undergoing different treatments. METHODS: Plasma pentosidine, biomarkers of inflammation, oxidative stress and nutritional status were investigated in CKD 1-2 (n = 37), CKD 3-4 (n = 54), CKD 5 non-dialyzed (CKD5-ND; n = 386), peritoneal dialysis (PD; n = 74) and hemodialysis (HD; n = 195) patients. Factors predicting plasma pentosidine were analysed by multivariate regression analysis and mortality risk was assessed by GENMOD procedure. RESULTS: Plasma pentosidine levels, which were higher in CKD5-ND, PD and HD groups than in CKD 1-2 group, were significantly lower in PD than in HD patients, and not different between PD patients and CKD5-ND patients. Pentosidine associated inversely with glomerular filtration rate (GFR), and additionally in PD with 8-hydroxy-2'-deoxyguanosine (8-OHdG), and interleukin 6 (IL-6); in HD with age, IL-6 and body mass index (BMI); in CKD5-ND with age, 8-OHdG, IL-6, high-sensitive C-reactive protein (hsCRP), and soluble vascular cell adhesion protein-1 (sVCAM-1); in CKD 3-4 with 8-OHdG and sVCAM-1; and in CKD 1-2 with age and sVCAM-1. In multivariate analysis, age (one standard deviation, 1-SD higher), malnutrition (subjective global assessment, SGA), oxidative stress (8-OHdG, 1-SD higher), and belonging to CKD5-ND, HD and PD cohorts associated with 1-SD higher pentosidine. In GENMOD, 1-SD higher pentosidine independently predicted all-cause mortality (relative risk, RR = 1.04; 95% confidence interval, CI, 1.01-1.08, p = 0.01) and CVD mortality (RR = 1.03; 95% CI, 1.01-1.06, p = 0.03) after adjusting for all confounders. CONCLUSIONS: Plasma pentosidine is markedly elevated in CKD and associates with low GFR, oxidative stress and inflammation, and is an independent predictor of mortality in CKD patients.

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-α 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-α 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-α inhibition both protect the kidney from I/R injury by reducing the accumulation of renal macrophages/monocytes and induction of major inflammatory cytokines.

Elevated Circulating S100A12 Associates with Vascular Disease and Worse Clinical Outcome in Peritoneal Dialysis Patients.

UNLABELLED: ♦ BACKGROUND: The pro-inflammatory receptor of advanced glycation end-products (RAGE)-ligand S100A12 is thought to promote, whereas anti-inflammatory soluble RAGE (sRAGE) may protect against, vascular disease. We evaluated circulating S100A12 and sRAGE in relation to vascular disease, inflammation, nutritional status, and mortality risk in peritoneal dialysis (PD) patients. ♦ METHODS: Plasma S100A12 and sRAGE, biomarkers of inflammation, nutritional status, and comorbidities were analyzed in 82 prevalent PD patients (median age 65 years; 70% men; median vintage 12 months) and, for comparative analysis, also in 190 hemodialysis (HD) patients and 50 control subjects. Associations between mortality risk and concentrations of S100A12 and sRAGE were assessed in PD and HD patients after a mean follow-up period of 31 and 29 months respectively using a competing risk Cox regression model. ♦ RESULTS: In PD patients, median S100A12, sRAGE and S100A12/sRAGE were markedly higher than in controls, and S100A12 was 1.9 times higher and median sRAGE 14% lower compared with HD patients. In PD patients, S100A12 associated with C-reactive protein (ρ = 0.46; p < 0.001) and interleukin-6 (ρ = 0.38; p < 0.001), and, negatively, with s-albumin (ρ = -0.27; p < 0.05) whereas sRAGE associated negatively with body mass index (ρ = -0.37; p < 0.001), fat body mass index (ρ = -0.34; p < 0.001), and lean body mass index (ρ = -0.36; p < 0.001). Peripheral vascular disease or cerebrovascular disease (PCVD) was present in 28% of PD patients and, in multivariate analysis, associated mainly with high S100A12 (odds ratio [OR] 3.52, p = 0.04). In both PD and HD patients, the highest versus other tertiles of S100A12 associated with increased mortality. In contrast, sRAGE did not associate with PCVD or mortality in PD and HD patients. ♦ CONCLUSIONS: Plasma S100A12 and sRAGE are markedly elevated in PD patients. Soluble RAGE was inversely related to body mass indices while S100A12 associated with increased inflammation, PCVD, and mortality, suggesting that S100A12 may identify PD patients at high risk for vascular disease and increased mortality.

Plasma S100A12 and soluble receptor of advanced glycation end product levels and mortality in chronic kidney disease Stage 5 patients.

BACKGROUND: Alterations in the advanced glycation end-products (AGE)-receptor of AGE (RAGE) system are linked to several chronic diseases, which may result from vascular damage. A high circulating level of the pro-inflammatory RAGE-ligand S100A12, also known as EN-RAGE, is thought to promote while a high level of soluble RAGE (sRAGE) is thought to protect against development of atherosclerotic cardiovascular disease (CVD). We evaluated circulating S100A12 and sRAGE in relation to clinical characteristics, nutritional status, inflammation and mortality risk in chronic kidney disease (CKD) Stage 5 patients starting on dialysis. METHODS: Plasma S100A12 and sRAGE, biomarkers of inflammation and nutritional status, and comorbidities were investigated in 200 CKD Stage 5 patients [median age of 56 years, 62% men and median glomerular filtration rate (GFR) of 6.2 mL/min/1.73 m(2)] in conjunction with initiation of dialysis therapy. Associations between mortality risk and S100A12 or sRAGE were assessed after a median follow-up period of 23 months. In addition, for comparative analyses, S100A12 and sRAGE levels were assessed also in 58 haemodialysis and 78 peritoneal dialysis patients after 1 year of dialysis, 56 CKD Stages 3-4 patients and 50 community-based control subjects. RESULTS: The median level of S100A12 was 4-fold higher, median sRAGE 2.4 higher and median ratio S100A12/sRAGE 2.27 times higher in CKD 5 patients than in controls. Similar alterations were observed in CKD 3-4 patients; however, CKD 5 patients had a higher median level of sRAGE than the CKD 3-4 patients. In the CKD 5 patients, S100A12 levels were higher in those with diabetes or CVD than in those without these comorbidities. Furthermore, S100A12 correlated with high-sensitivity C-reactive protein (hsCRP) levels (ρ = 0.53; P < 0.001) and a 1-SD higher level of S100A12 associated with increased all-cause mortality risk (hazard ratio 1.32, 95% confidence interval 1.01-1.73) after adjustment for age, sex, comorbidity, nutritional status and inflammation (hsCRP). In the CKD 5 patients, sRAGE correlated negatively with GFR (ρ = -0.26; P < 0.01) but sRAGE did not associate with hsCRP, comorbidities or mortality. CONCLUSIONS: Plasma concentrations of sRAGE, S100A12 and the ratio S100A12/sRAGE, are markedly elevated in CKD 5 patients starting on dialysis as well as in CKD 3-4 patients and prevalent dialysis patients suggesting that these alterations are typical for patients with moderate or severe CKD. In CKD 5 patients, an increased concentration of S100A12 are associated with inflammation, comorbidities and increased mortality risk whereas no such associations were observed for sRAGE. These results suggest that while high plasma S100A12 is an independent predictor of increased mortality risk, sRAGE does not seem to be a valid risk marker in this patient population.

Comparative associations of muscle mass and muscle strength with mortality in dialysis patients.

BACKGROUND AND OBJECTIVES: Reduced muscle mass and strength are prevalent conditions in dialysis patients. However, muscle strength and muscle mass are not congruent; muscle strength can diminish even though muscle mass is maintained or increased. This study addresses phenotype and mortality associations of these muscle dysfunction entities alone or in combination (i.e., concurrent loss of muscle mass and strength/mobility, here defined as sarcopenia). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study included 330 incident dialysis patients (203 men, mean age 53±13 years, and mean GFR 7±2 ml/min per 1.73 m(2)) recruited between 1994 and 2010 and followed prospectively for up to 5 years. Low muscle mass (by dual-energy x-ray absorptiometry appendicular mass index) and low muscle strength (by handgrip) were defined against young reference populations according to the European Working Group on Sarcopenia in Older People. RESULTS: Whereas 20% of patients had sarcopenia, low muscle mass and low muscle strength alone were observed in a further 24% and 15% of patients, respectively. Old age, comorbidities, protein-energy wasting, physical inactivity, low albumin, and inflammation associated with low muscle strength, but not with low muscle mass (multivariate ANOVA interactions). During follow-up, 95 patients (29%) died and both conditions associated with mortality as separate entities. When combined, individuals with low muscle mass alone were not at increased risk of mortality (adjusted hazard ratio [HR], 1.23; 95% confidence interval [95% CI], 0.56 to 2.67). Individuals with low muscle strength were at increased risk, irrespective of their muscle stores being appropriate (HR, 1.98; 95% CI, 1.01 to 3.87) or low (HR, 1.93; 95% CI, 1.01 to 3.71). CONCLUSIONS: Low muscle strength was more strongly associated with aging, protein-energy wasting, physical inactivity, inflammation, and mortality than low muscle mass. Assessment of muscle functionality may provide additional diagnostic and prognostic information to muscle-mass evaluation.

FTY720 mediates cytochrome c release from mitochondria during rat thymocyte apoptosis.

FTY720 is known to not only accelerate lymphocyte homing to secondary lymphoid organs but also induce apoptosis in lymphocytes. To investigate the effect of FTY720 in rat thymocytes, rats were intramuscularly injected with 10 mg/kg/day of FTY720. Light microscopy revealed obvious reductions in the size of the cortical region of thymuses treated with FTY720. FTY720 significantly reduced the total number of thymocytes, particularly affecting the CD4(+)8(+)TCRalphabeta(negative/low) population. TUNEL analysis showed that thymocyte apoptosis was induced in the cortical region and western blotting revealed activated caspase-3 and -6. Furthermore, caspase-9 was activated and the level of cytochrome c was increased. In contrast, the protein level of Bax did not increase following FTY720 treatment, suggesting that FTY720 may have perturbed mitochondrial function. Therefore, FTY720-induced apoptosis is initiated by the release of cytochrome c from mitochondria, resulting in the activation of caspases in rat thymocytes.

Development of a peritoneal sclerosis rat model using a continuous-infusion pump.

OBJECTIVE: Encapsulating peritoneal sclerosis (EPS) is a serious complication of continuous ambulatory peritoneal dialysis. Previous studies have created peritoneal sclerosis rat models using daily intraperitoneal injection of chlorhexidine gluconate (CG), but this technique is cumbersome and thickening of the peritoneum makes it difficult to evaluate the injection site. We therefore aimed to make a rat model using a continuous-infusion pump. METHODS: Various concentrations of CG (5%, 8%, 10%, 12%, and 14%) in ethanol were dissolved in saline within the infusion pumps, each of which was placed in the lower abdominal cavity of a male Wister rat. After a peritoneal equilibration test was performed, the rats were sacrificed and the lower anterior parietal and visceral peritoneum was removed. Each excised peritoneum was analyzed by macroscopic and microscopic examinations, including immunohistochemistry for the expression of transforming growth factor-beta 1 (TGF-beta1), vascular endothelial growth factor (VEGF), and alpha-smooth muscle actin (alphaSMA). The results were compared with those of control rats injected with ethanol dissolved in saline within the infusion pump and with no-pump rats. RESULTS: Two of the 5 rats in the 12% CG group and 3 of the 5 rats in the 14% CG group died of ileus within 14 days. All the rats in the 5%, 8%, and 10% CG groups survived to 28 days. Macroscopic examination in the 10% CG group showed bowel dilatation, bowel adhesion, and bloody ascites, similar to those seen in human EPS patients. All rats in each CG group showed the same extent of thickening of the submesothelial compact zone, proliferation of collagen fibers, and presence of numerous cells and neovascularization. Within same CG groups, an equal degree of thickening was observed at all sites of the peritoneum. TGF-beta1, VEGF, and alphaSMA were highly expressed in the peritoneum of the 10% CG group. CONCLUSION: We developed a novel method of creating a peritoneal sclerosis rat model using a continuous-infusion pump. Our technique is simple and highly reproducible, and will be useful in the study of peritoneal sclerosis mechanisms.

Evidence that FTY720 induces rat thymocyte apoptosis.

FTY720, a novel immunomodulator with the potential to improve immunosuppressive therapy after organ transplantation, is currently under clinical investigation. FTY720 drastically decreases blood lymphocytes, especially T cells, accelerating lymphocyte homing to secondary lymphoid organs. However, its immunosuppressive effects remain unknown. We investigated these effects in rat thymocytes. Rats were intramuscularly injected with 10mg/kg/day FTY720 or saline for 7days. Thymuses were removed on days 0, 1, 3, 5, 7 and 14 after treatment. Three-color analysis was performed with a flow cytofluorometer. Apoptotic nuclei in the tissue sections were identified by TUNEL. Genomic DNA was then extracted and samples were electrophoresed on 2.0% agarose gel. FTY720 reduced the total number of thymocytes and, with time, significantly reduced the percentage of CD4+8+ TCRalphabeta(negative/low) thymocytes. Light microscopy of thymuses of FTY720-treated rats revealed obvious reductions in the size of the cortical region. TUNEL analysis showed that FTY720 induced thymocyte apoptosis in the cortical region. Furthermore, DNA fragmentation was observed in thymocytes treated with FTY720, indicating thymocyte apoptosis. FTY720 reduced the number of CD4+8+ thymocytes before TCRalphabeta expression resulting in impaired thymocyte differentiation and maturation. This might be an immunosuppressive effect of FTY720.