An inhibitor of Krüppel-like factor 5 suppresses peritoneal fibrosis in mice

BACK GROUND

Krüppel-like transcription factor 5 (KLF5) is a transcription factor regulating cell proliferation, angiogenesis and differentiation. It has been recently reported that Am80, a synthetic retinoic acid receptor α-specific agonist, inhibits the expression of KLF5. In the present study, we have examined the expression of KLF5 in fibrotic peritoneum induced by chlorhexidine gluconate (CG) in mouse and evaluated that Am80, as an inhibitor of KLF5, can reduce peritoneal fibrosis.

METHODS

Peritoneal fibrosis was induced by intraperitoneal injection of CG into peritoneal cavity of ICR mice. Am80 was administered orally for every day from the start of CG injection. Control mice received only a vehicle (0.5% carboxymethylcellulose solution). After 3 weeks of treatment, peritoneal equilibration test (PET) was performed and peritoneal tissues were examined by immunohistochemistry.

RESULTS

The expression of KLF5 was less found in the peritoneal tissue of control mice, while KLF5 was expressed in the thickened submesothelial area of CG-injected mice receiving the vehicle. Am80 treatment reduced KLF5 expression and remarkably attenuated peritoneal thickening, accompanied with the reduction of type III collagen expression. The numbers of transforming growth factor β-positive cells, α-smooth muscle actin-positive cells and infiltrating macrophages were significantly decreased in Am80-treated group. PET revealed the increased peritoneal permeability in CG mice, whereas Am80 administration significantly improved the peritoneal high permeability state.

CONCLUSIONS

These results indicate the involvement of KLF5 in the progression of experimental peritoneal fibrosis and suggest that Am80 may be potentially useful for the prevention of peritoneal fibrosis through inhibition of KLF5 expression.

Renal outcomes of treatment with telmisartan in patients with stage 3-4 chronic kidney disease: A prospective, randomized, controlled trial (JINNAGA)

Objectives:

Although angiotensin II receptor blockers are effective for patients with chronic kidney disease, dose-dependent renoprotective effects of angiotensin II receptor blockers in patients with moderate to severe chronic kidney disease with non-nephrotic proteinuria are not known. Our aim was to elucidate the dose-dependent renoprotective effects of angiotensin II receptor blockers on such patients.

Methods:

A multicenter, prospective, randomized trial was conducted from 2009 to 2014. Patients with non-nephrotic stage 3–4 chronic kidney disease were randomized for treatment with either 40 or 80 mg telmisartan and were observed for up to 104 weeks. Overall, 32 and 29 patients were allocated to the 40 and 80 mg telmisartan groups, respectively. The composite primary outcome was renal death, doubling of serum creatinine level, transition to stage 5 chronic kidney disease, and death from any cause. Secondary outcomes included the level of urinary proteins and changes in the estimated glomerular filtration rate.

Results:

There was no difference in the primary outcome (p = 0.78) and eGFR (p = 0.53) between the two groups; however, after 24 weeks, urinary protein level was significantly lower in the 80 mg group than in the 40 mg group (p < 0.05). No severe adverse events occurred in either group, and the occurrence of adverse events did not significantly differ between them (p = 0.56).

Conclusion:

Our findings do not demonstrate a direct dose-dependent renoprotective effect of telmisartan. The higher telmisartan dose resulted in a decrease in the amount of urinary protein. Even though high-dose angiotensin II receptor blockers may be preferable for patients with stage 3–4 chronic kidney disease, the clinical importance of the study results may be limited. The study was registered in the UMIN-CTR (https://www.umin.ac.jp/ctr) with the registration number UMIN000040875.

Gene Transfer Using Nonviral Delivery Systems

In peritoneal dialysis, loss of peritoneal function is a major factor in treatment failure. The alterations in peritoneal function are related to structural changes in the peritoneal membrane, including peritoneal sclerosis with increased extracellular matrix. Although peritoneal sclerosis is considered reversible to some extent through peritoneal rest, which improves peritoneal function and facilitates morphological changes, there has been no therapeutic intervention and no drug against the development and progression of peritoneal sclerosis. Using recent biotechnological advances in genetic engineering, a strategy based on genetic modification of the peritoneal membrane could be a potential therapeutic maneuver against peritoneal sclerosis and peritoneal membrane failure. Before this gene therapy may be applied clinically, a safe and effective gene delivery system as well as the selection of a gene therapy method must be established. There are presently two kinds of gene transfer vectors: viral and nonviral. Viral vectors are used mainly as a gene delivery system in the field of continuous ambulatory peritoneal dialysis research; however, they have several problems such as immunogenicity and toxicity. On the other hand, nonviral vectors have several advantages over viral vectors. We review here gene transfer using nonviral vector systems in the peritoneum: electroporation, liposomes, and cationized gelatin microspheres. In the field of peritoneal dialysis, gene therapy research using nonviral vectors is presently limited. Improvement in delivery methods together with an intelligent design of targeted genes has brought about large degrees of enhancement in the efficiency, specificity, and temporal control of nonviral vectors.

A multicenter randomized controlled trial of tonsillectomy combined with steroid pulse therapy in patients with immunoglobulin A nephropathy

Background

The study aim was, for the first time, to conduct a multicenter randomized controlled trial to evaluate the effect of tonsillectomy in patients with IgA nephropathy (IgAN).

Methods

Patients with biopsy-proven IgAN, proteinuria and low serum creatinine were randomly allocated to receive tonsillectomy combined with steroid pulses (Group A; n = 33) or steroid pulses alone (Group B; n = 39). The primary end points were urinary protein excretion and the disappearance of proteinuria and/or hematuria.

Results

During 12 months from baseline, the percentage decrease in urinary protein excretion was significantly larger in Group A than that in Group B (P < 0.05). However, the frequency of the disappearance of proteinuria, hematuria, or both (clinical remission) at 12 months was not statistically different between the groups. Logistic regression analyses revealed the assigned treatment was a significant, independent factor contributing to the disappearance of proteinuria (odds ratio 2.98, 95% CI 1.01–8.83, P = 0.049), but did not identify an independent factor in achieving the disappearance of hematuria or clinical remission.

Conclusions

The results indicate tonsillectomy combined with steroid pulse therapy has no beneficial effect over steroid pulses alone to attenuate hematuria and to increase the incidence of clinical remission. Although the antiproteinuric effect was significantly greater in combined therapy, the difference was marginal, and its impact on the renal functional outcome remains to be clarified.

Involvement of leptin in the progression of experimentally induced peritoneal fibrosis in mice

Leptin is a hormone mainly produced by white adipose cells, and regulates body fat and food intake by acting on hypothalamus. Leptin receptor is expressed not only in the hypothalamus but in a variety of peripheral tissues, suggesting that leptin has pleiotropic functions. In this study, we investigated the effect of leptin on the progression of peritoneal fibrosis induced by intraperitoneal injection of chlorhexidine gluconate (CG) every other day for 2 or 3 weeks in mice. This study was conducted in male C57BL/6 mice and leptin-deficient ob/ob mice. Peritoneal fluid, blood, and peritoneal tissues were collected 15 or 22 days after CG injection. CG injection increased the level of leptin in serum and peritoneal fluid with thickening of submesothelial compact zone in wild type mice, but CG-injected ob/ob mice attenuate peritoneal fibrosis, and markedly reduced the number of myofibroblasts, infiltrating macrophages, and blood vessels in the thickened submesothelial area. The 2-week leptin administration induced a more thickened peritoneum in the CG-injected C57BL/6 mice than in the PBS group. Our results indicate that an upregulation of leptin appears to play a role in fibrosis and inflammation during peritoneal injury, and reducing leptin may be a therapeutically potential for peritoneal fibrosis.

Association between cystatin C and arteriosclerosis in the absence of chronic kidney disease

AIM

Chronic kidney disease (CKD) is a known risk factor for cardiovascular disease (CVD). Cystatin C was recently reported to be an endogenous surrogate of kidney function, and a high level of cystatin C is reported to be a strong predictor of CVD; however, the association between cystatin C and arteriosclerosis in a non-CKD population is unclear. This study aimed to clarify the association between cystatin C and arteriosclerosis in a non-CKD population.

METHODS

Of the 637 Japanese adults (264 men, 373 women) enrolled, we analyzed 446 participants with an estimated glomerular filtration rate (eGFR) >60 mL/min and no proteinuria (177 men, 269 women) without a history of CVD. Kidney function was evaluated according to serum cystatin C levels and eGFR. Arteriosclerosis was evaluated on the basis of the cardio-ankle vascular index (CAVI) and carotid intima-media thickness (CIMT).

RESULTS

The mean age of our subjects was 67.0±10.0 years. No variables showed any significant differences according to gender. The results of multiple linear regression analysis showed a significant correlation between serum cystatin C and CAVI only in women, but not CIMT.

CONCLUSION

We observed a significant correlation between cystatin C and CAVI, which is a marker of early-stage arteriosclerosis, in women in a non-CKD population with no proteinuria and eGFR>60 mL/min.

Glomerular repair retardation via blocking of angiotensin II type 1a receptor pathway in a mouse glomerulonephritis model

BACKGROUND/AIMS

To examine the role of the angiotensin II (ATII) type 1a receptor (AT1-R) pathway in renal tissue damage and repair, we investigated reversible glomerular injury in a mouse model of habu snake venom (HSV)-induced glomerulonephritis using AT1-R-deficient (AT1a-/-) mice and AT1-R antagonist-treated mice.

METHODS

Experimental glomerulonephritis was induced by single administration of HSV to AT1a(+/+) mice (HSV group) and AT1a(-/-) mice (KO-HSV group) and AT1-R antagonist-treated BL6 mice (HSV-ARB group). Morphological change and expression levels of type IV collagen, CD31, and vascular endothelial growth factor (VEGF) were analyzed.

RESULTS

The HSV group showed increased mesangial matrix expansion on day 7, which returned to preinjection levels by day 56, while mes-angial matrix expansion and increased type IV collagen expression were seen throughout days 7 to 56 in the KO-HSV group. The KO-HSV group showed fewer CD31-positive capillary loops and a marked decrease in the number of VEGF-positive cells in the glomeruli than the HSV group. VEGF administration to the KO-HSV group facilitated glomerular capillary repair and reconstruction. The HSV-ARB group showed the same delay in glomerular repair as that seen in the KO-HSV group.

CONCLUSION

Our results indicate that blocking of the ATII-AT1R pathway delays glomerular repair via angiogenesis inhibition, followed by reduced induction of VEGF.

Identification of a novel mutation and prevalence study for fabry disease in Japanese dialysis patients

Fabry disease--a genetic disorder characterized by the accumulation of globotriaosylceramide in cell lysosomes resulting from an X-linked deficiency of α-galactosidase A activity--presents with multiorgan manifestations, including progressive renal disease. Recently, its prevalence has been reported to be higher in hemodialysis (HD) patients than in the general population. We, therefore, examined patients on maintenance dialysis living in the Nagasaki Prefecture, Japan, to clarify the prevalence of Fabry disease. We screened 933 patients on maintenance dialysis, who were residents of Nagasaki Prefecture in Japan, for α-galactosidase A activity using a dried blood spot on filter paper. Patients with low α-galactosidase A activity were clinically assessed; subsequently, genetic analysis of the α-Galactosidase A gene (MIM:30064) was performed in these patients. Of the 933 patients, 55 had low α-galactosidase A activity; of these, one male and two females had α-Galactosidase A mutations. The prevalence of Fabry disease was thus 0.32%, which was similar to that reported previously. However, one mutation was newly identified, while the E66Q mutation observed in two patients was as previously identified. These two patients with the E66Q mutation were excluded because of the possibility of polymorphism; the prevalence of Fabry disease in the HD population was finally calculated to be 0.11%. The prevalence of Fabry disease in patients on maintenance dialysis living in Nagasaki Prefecture was 0.32%. Dried blood spot screening was considered as a simple and effective method for screening patients on maintenance dialysis for Fabry disease.

22-Oxacalcitriol prevents progression of peritoneal fibrosis in a mouse model

OBJECTIVE

Vitamin D plays an important role in calcium homeostasis and is used to treat secondary hyperparathyroidism among dialysis patients. The biologic activity of vitamin D and its analogs is mediated by vitamin D receptor (VDR), which is distributed widely throughout the body. Recent papers have revealed that low vitamin D levels are correlated with severe fibrosis in chronic diseases, including cystic fibrosis and hepatitis. The aim of the present study was to evaluate the protective effects of vitamin D against the progression of peritoneal fibrosis.

METHODS

Peritoneal fibrosis was induced by injection of chlorhexidine gluconate (CG) into the peritoneal cavity of mice every other day for 3 weeks. An analog of vitamin D, 22-oxacalcitriol (OCT), was administered subcutaneously daily from initiation of the CG injections. The peritoneal tissue was excised at 3 weeks. Changes in morphology were assessed by hematoxylin and eosin staining. Expression of VDR, alpha smooth muscle actin (as a marker of myofibroblasts), type III collagen, transforming growth factor β(TGF-β), phosphorylated Smad2/3, F4/80 (as a marker of macrophages), and monocyte chemoattractant protein-1 (MCP-1) was examined by immunohistochemistry. Southwestern histochemistry was used to detect activated nuclear factor κB (NF-κB).

RESULTS

In the CG-injected mice, immunohistochemical analysis revealed expression of VDR in mesothelial cells, myofibroblasts, and macrophages in the thickened submesothelial zone. Treatment with OCT significantly prevented peritoneal fibrosis and reduced the accumulation of type III collagen in CG-treated mice. Among the markers of fibrosis, the numbers of myofibroblasts, cells positive for TGF-β, and cells positive for phosphorylated Smad2/3 were significantly decreased in the OCT-treated group compared with the vehicle-treated group. Furthermore, OCT suppressed inflammatory mediators of fibrosis, as shown by the reduced numbers of activated NF-κB cells, macrophages, and MCP-1-expressing cells.

CONCLUSIONS

Our results indicate that OCT attenuates peritoneal fibrosis, an effect accompanied by reduced numbers of myofibroblasts, infiltrating macrophages, and TGF-β-positive cells, suggesting that vitamin D has potential as a novel therapeutic agent for preventing peritoneal sclerosis.

Imaging mass spectrometry analysis reveals an altered lipid distribution pattern in the tubular areas of hyper-IgA murine kidneys

Immunoglobulin A (IgA) nephropathy is the most common glomerular disease worldwide. To investigate the pathogenesis of this renal disease, we used animal models that spontaneously develop mesangioproliferative lesions with IgA deposition, which closely resemble the disease in humans. We analyzed the molecular distribution of lipids in hyper-IgA (HIGA) murine kidneys using matrix-assisted laser desorption/ionization-quadrupole ion trap-time of flight (MALDI-QIT-TOF)-based imaging mass spectrometry (IMS), which supplies both spatial distribution of the detected molecules and allows identification of their structures by their molecular mass signature. For both HIGA and control (Balb/c) mice, we found two phosphatidylcholines, PC(16:0/22:6) and PC(18:2/22:6), primarily located in the cortex area and two triacylglycerols, TAG(16:0/18:2/18:1) and TAG(18:1/18:2/18:1), primarily located in the hilum area. However, several other molecules were specifically seen in the HIGA kidneys, particularly in the tubular areas. Two HIGA-specific molecules were O-phosphatidylcholines, PC(O-16:0/22:6) and PC(O-18:1/22:6). Interestingly, common phosphatidylcholines and these HIGA-specific ones possess 22:6 lipid side chains, suggesting that these molecules have a novel, unidentified renal function. Although the primary structure of the HIGA-specific molecules corresponding to m/z 854.6, 856.6, 880.6, and 882.6 remained undetermined, they shared similar fragmentation patterns, indicating their relatedness. We also showed that all the HIGA-specific molecules were derived from urine, and that artificial urinary stagnation-due to unilateral urethral obstruction-caused HIGA-specific distribution of lipids in the tubular area.

Thalidomide prevents the progression of peritoneal fibrosis in mice

Thalidomide is clinically recognized as a therapeutic agent for multiple myeloma and has been known to exert anti-angiogenic actions. Recent studies have suggested the involvement of angiogenesis in the progression of peritoneal fibrosis. The present study investigated the effects of thalidomide on the development of peritoneal fibrosis induced by injection of chlorhexidine gluconate (CG) into the mouse peritoneal cavity every other day for 3 weeks. Thalidomide was given orally every day. Peritoneal tissues were dissected out 21 days after CG injection. Expression of CD31 (as a marker of endothelial cells), proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), α-smooth muscle actin (as a marker of myofibroblasts), type III collagen and transforming growth factor (TGF)-β was examined using immunohistochemistry. CG group showed thickening of the submesothelial zone and increased numbers of vessels and myofibroblasts. Large numbers of VEGF-, PCNA-, and TGF-β-positive cells were observed in the submesothelial area. Thalidomide treatment significantly ameliorated submesothelial thickening and angiogenesis, and decreased numbers of PCNA- and VEGF-expressing cells, myofibroblasts, and TGF-β-positive cells. Moreover, thalidomide attenuated peritoneal permeability for creatinine, compared to the CG group. Our results indicate the potential utility of thalidomide for preventing peritoneal fibrosis.

Glomerulocystic kidney disease in an adult with enlarged kidneys: a case report and review of the literature

We report the case of a 31-year-old male with enlarged kidneys and glomerulocystic kidney disease (GCKD). The patient had no family history of renal disease or other diseases. On initial presentation he complained of poor eyesight, and hypertensive retinopathy and elevated serum creatinine (5.0 mg/dl) were found at that time. Renal biopsy showed cystic dilatation of Bowman's capsule and atrophy of the glomerular tuft. Thus, an adult case of sporadic GCKD was diagnosed. Based on previous reports, kidney size in patients with adult type GCKD varies from small to large. Our patient's kidneys are the largest ever reported (right kidney was 22 cm×10 cm, left kidney was 19 cm×10 cm). A review of the literature dealing with sporadic adult GCKD suggested that it is difficult to diagnose this disease early in its course.

[Case in which renal function improved following stent-graft placement in the aorta two months after the onset of stanford type B acute aortic dissection]

A 48-year-old man was admitted to the Department of Cardiovascular Surgery in our hospital after developing Stanford type B acute aortic dissection with a patent false lumen in July 2008. Conservative treatment involving rest and antihypertensive therapy was provided following admission. Urine volume decreased from day 9, and serum creatinine increased to 7.7 mg/dL. As it was suspected that the reduced renal blood flow was caused by progression of aortic dissection, contrast-enhanced computed tomography (CT)was performed. The left kidney showed reduced enhancement and the right kidney was heterogeneously enhanced. The dissection had extended to the left renal artery, and the reduced renal blood flow caused by narrowing of the left renal artery was thought to have caused the renal dysfunction. As elevated urea nitrogen and serum creatinine levels and hyperkalemia persisted, hemodialysis was performed a total of four times. Although the patient was subsequently withdrawn from dialysis, he continued to display severe renal dysfunction and was transferred to our department on day 28 for the treatment of renal failure. Conservative treatment was continued, but the maximum diameter of the thoracic aorta gradually increased, and stent placement at the entry of aortic dissection was indicated. On day 86, two stent-grafts were placed for entries at the distal site of the descending aorta and the distal site of the aortic arch. Postoperative abdominal contrast-enhanced CT showed expansion of the true lumen, and blood flow and contrast enhancement improved in both kidneys. Postoperatively, serum creatinine gradually decreased, improving to 1.16 mg/dL on day 96. Renography in the third month after stent-graft placement showed improved renal function in both kidneys. These findings suggest that even at approximately 2 months after the onset of acute renal failure associated with aortic dissection, renal function can be improved by restoring blood flow in the renal arteries.

Diffuse liver metastasis of small cell lung cancer causing marked hepatomegaly and fulminant hepatic failure

A 62-year-old female was admitted for examination of an abnormal liver function. Plain CT and MRI of the abdomen showed marked hepatomegaly but no visible nodular lesion in the liver. On the 3rd hospital day she had hepatic encephalopathy and was treated with a course of high-dose steroids, but ultimately died of disease progression on the 7th hospital day. An autopsy revealed a small pulmonary nodule with the histological findings showing small cell carcinoma. There was almost complete parenchymal replacement with metastatic tumor in the liver. Neoplastic involvement of the liver should be considered in the differential diagnosis of fulminant hepatic failure of unknown etiology.

Two patients who developed leptospirosis-associated acute renal failure within the same season

In the autumn two patients with general malaise were consecutively admitted to the department of internal medicine of our hospital in the northern region of Nagasaki Prefecture. Since both patients were engaged in rice farm work and showed conjunctival suffusion and pain of the gastrocnemius muscle, leptospirosis was suspected. The first patient required temporary hemodialysis for renal dysfunction, whereas liver dysfunction developed in the second patient. The disease was remitted by antimicrobial agents. A diagnosis of leptospirosis was made serologically in both patients. Leptospirosis should be considered as a differential diagnosis when a patient engaged in farm work in the autumn has typical symptoms, and an early initiation of treatment after onset is important.

Membranous nephropathy and Kimura's disease manifesting a hip mass. A case report with literature review

We report a case of Kimura's disease with membranous nephropathy. A 15-year-old Japanese boy was referred to our hospital with proteinuria and a subcutaneous mass in the hip. Renal biopsy demonstrated secondary membranous nephropathy (MN) with mild mesangial proliferation and some electron-dense deposits in the mesangium. Laboratory tests revealed eosinophilia and a high level of serum IgE, which are common findings in Kimura's disease. A biopsy of the mass in the hip was performed and Kimura's disease was diagnosed. Treatment with oral prednisolone resulted in a decrease of proteinuria and regression of the subcutaneous mass. Kimura's disease should be included in the differential diagnosis of secondary MN.

Membranous nephropathy complicating nasopharyngeal carcinoma

The patient was a 38-year-old woman diagnosed with nephrotic syndrome. Steroid pulse therapy and mizoribine was started in late October 2002 and continued for about 10 months, but no apparent therapeutic effect was obtained. During this period, the patient was diagnosed with nasopharyngeal carcinoma. As nephrotic syndrome did not improve, renal biopsy was performed and membranous nephropathy (MN) was diagnosed. After resection of nasopharyngeal carcinoma was performed, the urinary protein level decreased rapidly. Since MN caused by nasopharyngeal carcinoma is very rare, this represents an interesting case of malignancy-associated MN.

[Healthcare linkage for aging population with end-stage renal failure]

The mean age of Japanese patients requiring a dialysis induction is 67.7-year-old in 2007. Comparing with hemodialysis, peritoneal dialysis is fit for old patients because of a lesser degree of influence on cardiovascular system and a lesser degree of restriction on the issue of water and food. However, a home care system for patients with peritoneal dialysis has not been established. In Nagasaki city, "Nagasaki Home Doctor Net" supports the home care through many kinds of medical occupational linkage. By applying this system, we are trying to establish a supporting system for elderly patients with peritoneal dialysis. Furthermore, in each patient, we make the "Putit-mailing list" on Internet. It is a very effective tool for all medical care members to send and get the information about the patients on time and timely.

Serum pro-hepcidin level and iron homeostasis in Japanese dialysis patients with erythropoietin (EPO)-resistant anemia

BACKGROUND

Resistance to EPO therapy in hemodialysis (HD) patients is ascribed to inflammation and iron deficiency. Hepcidin, an antimicrobial peptide, is a key regulator of iron metabolism and synthesis of hepcidin is regulated by iron status and inflammation. The role of hepcidin in the pathogenesis of EPO-resistant anemia was assessed through measurement of serum pro-hepcidin in HD patients.

MATERIAL/METHODS

Serum pro-hepcidin was measured by ELISA in 57 HD patients, who were divided into three groups: Group I (n=19) had EPO-resistance anemia, based on serum ferritin of > or =100 ng/ml and EPO dose (9,000 IU/week maximum dose for 6 months); Group II (n=19) had iron-deficiency anemia, based on serum ferritin of <100 ng/ml and/or <20% transferrin iron saturation (TSAT); and Group III (n=19) had no iron deficiency and anemia. Nineteen age- and sex-matched healthy volunteers were enrolled as controls (Group IV).

RESULTS

Serum pro-hepcidin was significantly lower in Group II than in other groups. In Group I, serum pro-hepcidin did not differ significantly from controls. Serum levels of ferritin, hs-CRP and IL-6 were higher in Group I than in other groups, and serum sTfR was higher in Groups I and II than in controls.

CONCLUSIONS

In EPO resistant anemia, multiple factors, including iron and inflammation related conditions, are likely to affect the level of hepcidin and this may explain the lack of elevated serum hepcidin in this condition.

Involvement of bone marrow-derived endothelial progenitor cells in glomerular capillary repair in habu snake venom-induced glomerulonephritis

Neovasculogenesis is essential in tissue remodeling. Endothelial progenitor cells (EPCs) mobilize from bone marrow (BM) and participate in neovasculogenesis. This study examined the role of EPCs in a model of reversible glomerulonephritis induced by habu snake venom (HSV). Lethally irradiated FVB/N wild-type mice were transplanted with BM cells from donor transgenic mice expressing beta-galactosidase gene under the control of endothelial-specific tie-2 promoter. HSV or saline was injected intravenously after BM transplantation (BMT). The kidneys were removed before injection and at days 1, 7, 28, and 56 after injection. beta-Galactosidase-expressing cells were identified by X-gal staining. The expressions of CD31 (endothelial cell marker) and vascular endothelial cell growth factor (VEGF) in renal tissues were examined by immunohistochemistry. In BMT mice injected with saline, few X-gal-positive cells were detected in glomeruli. In HSV-injected mice, X-gal-positive EPCs were increased in damaged glomeruli, reaching maximum at day 28. Recovery of glomeruli was observed at day 56 in association with reduction of X-gal-positive EPCs. VEGF overexpression was detected in glomerular epithelial and endothelial cells, mesangial cells, and EPCs. Our results indicated that EPCs were mobilized into the damaged glomeruli, suggesting EPCs participation in glomerular capillary repair of damaged glomeruli in HSV-induced glomerulonephritis.

Cowfish (Umisuzume, Lactoria diaphana) poisoning with rhabdomyolysis

A 40-year-old man developed weakness and myalgia of the shoulders and brachia nine hours after eating a cowfish (Umisuzume, Lactoria diaphana). A clinical symptom showed rhabdomyolysis and serum creatine phosphokinase was elevated to 180,000 IU/L on day 3. Cardiopulmonary arrest and acute renal failure developed after 59 hours and hemodiafiltration was performed. Cerebral death was diagnosed on day 9 and the patient died on day 16. The case has the characteristic clinical course of palytoxin poisoning, which has also been reported as blue humphead parrotfish poisoning from other kinds of fish.

Suppression of renal tubulointerstitial fibrosis by small interfering RNA targeting heat shock protein 47

BACKGROUND/AIM

Unilateral ureteral obstruction (UUO) is a well-established model for tubulointerstitial fibrosis. During the progression of tubulointerstitial fibrosis, upregulation of collagen synthesis and subsequent accumulation of collagen were observed in the tubulointerstitial area. Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone and plays an essential role in regulating collagen synthesis. We designed small interfering RNA (siRNA) sequences for HSP47 mRNA to examine whether HSP47 is involved in the progression of renal tubulointerstitial fibrosis in a mouse UUO model.

METHODS

The HSP47 siRNA was injected once via the ureter at the time of UUO preparation. We also applied a new gene delivery system for siRNA using cationized gelatin microspheres. The kidneys were harvested 7 and 14 days after UUO. The HSP47 and type I, III, and IV collagen expression levels were analyzed by immunohistochemistry and Western blotting.

RESULTS

Seven days after UUO, the expression levels of HSP47 and type I, III, and IV collagens were markedly upregulated in obstructed kidneys or green fluorescent protein siRNA treated obstructed kidneys. HSP47 siRNA injection significantly reduced the protein expression levels and significantly diminished the accompanying interstitial fibrosis. Moreover, cationized gelatin microspheres as a delivery system enhanced and lengthened the antifibrotic effect of HSP47 siRNA.

CONCLUSIONS

Our results indicate that HSP47 is a candidate target for the prevention of tubulointerstitial fibrosis and that selective blockade of the HSP47 expression by using siRNA could be a potentially useful therapeutic approach for patients with renal disease.

Prednisolone co-administered with losartan confers renoprotection in patients with IgA nephropathy

Background

Treatment options for progressive IgA nephropathy are limited.

Methods

We performed a small, randomized controlled trial to evaluate the effects of prednisolone (PSL, 30 mg/dL, gradually tapered to 5 mg/dL over two years) plus 50 mg/day of losartan (LST, an angiotensin II receptor blocker) or PSL alone on IgA nephropathy. We separated 38 patients (age, 33 ± 11 years; creatinine clearance, 103 ± 31 mL/min; proteinuria, 1.6 ± 0.5 g/day) into two groups that were treated with either PSL plus LST or PSL alone, and compared the proteinuria and creatinine clearance after two years. Baseline and histopathological data did not significantly differ between the two groups.

Results

Two years of treatment in both groups significantly decreased proteinuria compared with baseline, and PSL plus LST (from 1.6 ± 0.6 to 0.3 ± 0.1 g/day, p < 0.05) was more effective than PSL alone (from 1.6 ± 0.3 to 0.5 ± 0.1 g/day, p < 0.05). Creatinine clearance in both groups was similar at the start of study but significantly differed at the end of the study (PSL plus LST, 104.3 ± 36.4 to 100.4 ± 38.9 mL/min; PSL alone, 103.4 ± 28.5 to 84.8 ± 34.3 mL/min, p < 0.05).

Conclusions

Combined therapy with PSL plus LST appears to be more effective than PSL alone in reducing proteinuria and protecting renal function in patients with IgA nephropathy.

MAP kinase-dependent, NF-kappaB-independent regulation of inhibitor of apoptosis protein genes by TNF-alpha

The inhibitor of apoptosis protein (IAP) family of molecules regulates apoptotic processes triggered by various stimuli. However, the mechanisms involved in the regulation of the IAP genes are not fully understood. In this report, we examined roles of nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein (MAP) kinases in tumor necrosis factor-alpha (TNF-alpha)-induced expression of IAP genes. In human endothelial cells, TNF-alpha induced c-IAP1 and c-IAP2, but not XIAP and TIAP/Survivin, at the transcriptional level. Inactivation of NF-kappaB by overexpression of a super-repressor mutant of IkappaBalpha did not affect the induction of IAPs by TNF-alpha. In contrast, extracellular signal-regulated kinase, p38 MAP kinase, and c-Jun N-terminal kinase were activated after stimulation with TNF-alpha, and inhibition of each kinase by PD098059, SB203580, curcumin, or SP600125 substantially attenuated the TNF-alpha-induced c-IAP1 and c-IAP2 expression. To examine whether the MAP kinases-mediated induction of IAPs contributes to survival of TNF-alpha-exposed cells, cells were pretreated with MAP kinase inhibitors and stimulated with TNF-alpha. Treatment with kinase inhibitors alone did not induce apoptosis but enhanced markedly TNF-alpha-triggered apoptosis. Furthermore, overexpression of either c-IAP1 or c-IAP2 diminished the apoptosis-promoting effects of MAP kinase inhibitors. These data indicated that TNF-alpha induced expression of c-IAP1 and c-IAP2 via MAP kinases, but not via NF-kappaB, and that MAP kinases participated in the inhibition of apoptosis by induction of c-IAPs in TNF-alpha-stimulated endothelial cells.

Aldosterone breakthrough during therapy with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers in proteinuric patients with immunoglobulin A nephropathy

BACKGROUND

We are investigating whether aldosterone breakthrough negatively impacts on the antiproteinuric effects of angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin II receptor blockers (ARB).

METHODS

We examine the role of aldosterone breakthrough in 43 normotensive, proteinuric (0.7 +/- 0.3 g/day) outpatients (aged 41.5 +/- 10.9 years) with immunoglobulin A nephropathy (IgAN) accompanied by stable renal function (creatinine clearance >50 mL/min). The patients were treated with temocapril (1 mg; n = 14), losartan (12.5 mg; n = 16), or a combination therapy (n = 13) for 12 months. We prospectively evaluated blood pressure (BP), urinary protein excretion (UPE), biochemical parameters and the renin-angiotensin-aldosterone system before and after 12 months of treatment.

RESULTS

Although the overall plasma aldosterone concentrations values did not change after any of the treatments administered for 12 months, they eventually increased in 23 (temocapril, seven patients; losartan, eight patients; combination, seven patients) of the 43 patients (53.4%; aldosterone breakthrough), and fell in the remainder (46.6%). Blood pressure and renal function did not differ among the three groups at 12 months. In contrast, UPE was significantly higher in patients with, than without aldosterone breakthrough during temocapril and losartan administration. However, combination therapy induced a more remarkable reduction in UPE regardless of aldosterone breakthrough.

CONCLUSIONS

A combination of ACE inhibitors and ARB in normotensive patients with IgAN produces a more profound decrease in proteinuria than either monotherapy. This additive antiproteinuric effect is not dependent on aldosterone breakthrough. Additional larger, prospective, randomized studies will be needed for general acceptance of this strategy.

Upregulation of cyclooxygenases by retinoic acid in rat mesangial cells

All-trans retinoic acid (ATRA) increases the expression of COX-1 and COX-2 and the production of PGE2, a prostaglandin with anti-inflammatory effects in human mesangial cells (MC). COX-2 increased through a transcriptional mechanism independent of retinoic acid receptors (RAR) and retinoid X receptors (RXR) and dependent on extracellular regulated kinase-1/2 (ERK1/2), that became phosphorylated 5 min after ATRA addition. Here, in rat MC, ATRA also upregulated COX isoenzymes and PGE2 production, but not in the same way as in human MC: (1) PGE2 production increased only slightly; (2) RAR and RXR were involved in the transcriptional upregulation of COX-2 by ATRA since the RAR-pan-antagonist AGN193109 or the RXR-pan-antagonist HX531 abolished the induction of COX-2 mRNA whereas the RAR-pan-agonist TTNPB or the RXR-pan-agonist AGN194204 induced expression of COX-2, and (3) ERK1/2 phosphorylation, though important for COX-2 upregulation, took more than 1 h. Therefore the regulation of COX by ATRA exhibits striking differences between human and rat MC.

Gene transfer using nonviral delivery systems

In peritoneal dialysis, loss of peritoneal function is a major factor in treatment failure. The alterations in peritoneal function are related to structural changes in the peritoneal membrane, including peritoneal sclerosis with increased extracellular matrix. Although peritoneal sclerosis is considered reversible to some extent through peritoneal rest, which improves peritoneal function and facilitates morphological changes, there has been no therapeutic intervention and no drug against the development and progression of peritoneal sclerosis. Using recent biotechnological advances in genetic engineering, a strategy based on genetic modification of the peritoneal membrane could be a potential therapeutic maneuver against peritoneal sclerosis and peritoneal membrane failure. Before this gene therapy may be applied clinically, a safe and effective gene delivery system as well as the selection of a gene therapy method must be established. There are presently two kinds of gene transfer vectors: viral and nonviral. Viral vectors are used mainly as a gene delivery system in the field of continuous ambulatory peritoneal dialysis research; however, they have several problems such as immunogenicity and toxicity. On the other hand, nonviral vectors have several advantages over viral vectors. We review here gene transfer using nonviral vector systems in the peritoneum: electroporation, liposomes, and cationized gelatin microspheres. In the field of peritoneal dialysis, gene therapy research using nonviral vectors is presently limited. Improvement in delivery methods together with an intelligent design of targeted genes has brought about large degrees of enhancement in the efficiency, specificity, and temporal control of nonviral vectors.

Nephronophthisis in two siblings

We describe here two sisters with nephronophthisis, which was not detected until the development of endstage renal failure. Twenty- and 15-year-old female siblings were admitted to our hospital for further examination of renal dysfunction. No urinalysis abnormalities had been found in yearly health checks in either patient. The serum creatinine level was 7.2 mg/dl in case 1 (the 20-year-old) and 6.4 mg/dl in case 2. Medical history, physical findings, and laboratory tests showed no evidence of urinary tract infection, use of any drugs, arthritis, or skin eruptions. To identify the cause of the renal failure, open left renal biopsies were performed in both patients. Histopathological findings were very similar in the two patients and included marked tubular and interstitial changes (tubular dilatation, focal tubular atrophy, interstitial fibrosis, and infiltration of mononuclear cells). The glomeruli were devoid of mesangial proliferation, mesangial expansion, and adhesion of Bowman's capsule. Based on the clinical and pathological findings, the final diagnosis was nephronophthisis in both patients. It is important to remember that some progressive renal diseases, including nephronophthisis, cannot be detected even by annual urinary screening tests, which are widely performed in Japan.

TNP-470, an angiogenesis inhibitor, suppresses the progression of peritoneal fibrosis in mouse experimental model

BACKGROUND

In patients on long-term peritoneal dialysis (PD), angiogenesis and vasculopathy are observed in the peritoneum, and the degree of vascularization correlates with the area of fibrotic tissue, suggesting the involvement of angiogenesis in the progression of peritoneal fibrosis. The aim of the present study was to evaluate the effect of TNP-470, an anti-angiogenic compound, on the development of peritoneal fibrosis induced by chlorhexidine gluconate (CG).

METHODS

Peritoneal fibrosis was induced by injection of CG into peritoneal cavity of Institute for Cancer Research (ICR) mice. TNP-470 was injected subcutaneously with CG. Mice were sacrificed, and peritoneal tissues were dissected out at days eight and 16 after CG and TNP-470 injection. The expression patterns of CD31 (as a marker of endothelial cells), vascular endothelial cell growth factor (VEGF), alpha-smooth muscle actin (as a marker of myofibroblasts), heat shock protein 47 (HSP47), type III collagen, F4/80 (as a marker of mice macrophages), proliferating cell nuclear antigen (PCNA), and cyclin-dependent kinase 2 (Cdk2) were examined by immunohistochemistry.

RESULTS

CG-injected mice showed thickening of the submesothelial zone and increased number of vessels, myofibroblasts, and infiltrating macrophages. The expression levels of VEGF, type III collagen, and HSP47 were increased, and a large number of PCNA-positive cells and Cdk2-expressing cells were observed in the thickened submesothelial area. Treatment with TNP-470 suppressed the submesothelial zone thickening and reduced collagen III expression as well as angiogenesis. TNP-470 also decreased the number of VEGF-expressing cells, myofibroblasts, macrophages, PCNA-positive cells, and Cdk2-expressing cells.

CONCLUSION

Our results indicate the involvement of angiogenesis in the progression of peritoneal fibrosis, and suggest that TNP-470 may be potentially useful for the prevention of peritoneal fibrosis through inhibition of angiogenesis and suppression of myofibroblast proliferation.

Cellular defense against H2O2-induced apoptosis via MAP kinase-MKP-1 pathway

Mitogen-activated protein (MAP) kinase phosphatase-1 (MKP-1) is an oxidative stress-inducible gene. In this study, we investigated signaling pathways involved in oxidative stress-induced MKP-1 expression and its role in apoptosis of rat mesangial cells. Northern and Western blot analyses showed that H(2)O(2) induced expression of MKP-1 mRNA and protein in a dose-dependent manner, without affecting the stability of the transcript. H(2)O(2) induced phosphorylation of extracellular signal-regulated kinase, p38 MAP kinase, and c-Jun N-terminal kinase and consequently activated activator protein 1 (AP-1). Selective inhibitors of individual MAP kinases or a dominant-negative mutant of c-jun significantly suppressed the expression of MKP-1 by H(2)O(2). Inhibition of MKP-1 by a protein tyrosine phosphatase inhibitor (vanadate) enhanced H(2)O(2)-triggered apoptosis. Consistently, transfection with a wild-type MKP-1, but not its catalytically inactive mutant MKP-1CS, attenuated H(2)O(2)-induced apoptosis. These data elucidate, for the first time, that induction of MKP-1 by H(2)O(2) is mediated by the MAP kinase-AP-1 pathway and that the induced MKP-1 is involved in cellular defense against oxidative stress-induced apoptosis of mesangial cells.

Antisense oligonucleotides against collagen-binding stress protein HSP47 suppress peritoneal fibrosis in rats

BACKGROUND

Peritoneal fibrosis is a serious complication in patients on continuous ambulatory peritoneal dialysis (CAPD), but the molecular mechanism of this process remains unclear. Heat shock protein 47 (HSP47), a collagen-specific molecular chaperone, is essential for biosynthesis and secretion of collagen molecules, and is expressed in the tissue of human peritoneal fibrosis. In the present study, we examined the effect of HSP47 antisense oligonucleotides (ODNs) on the development of experimental peritoneal fibrosis induced by daily intraperitoneal injections of chlorhexidine gluconate (CG).

METHODS

HSP47 antisense or sense ODNs were injected simultaneously with CG from day 14, after injections of CG alone. Peritoneal tissue was dissected out 28 days after CG injection. The expression patterns of HSP47, type I and type III collagen, alpha-smooth muscle actin (alpha-SMA), as a marker of myofibroblasts, ED-1 (as a marker of macrophages), and factor VIII were examined by immunohistochemistry.

RESULTS

In rats treated with CG alone, the submesothelial collagenous compact zone was thickened, where the expression levels of HSP47, type I and type III collagen and alpha-SMA were increased. Marked macrophage infiltration was also noted and the number of vessels positively stained for factor VIII increased in the CG-treated group. Treatment with antisense ODNs, but not sense ODNs, abrogated CG-induced changes in the expression of HSP47, type I and III collagen, alpha-SMA, and the number of infiltrating macrophages and vessels.

CONCLUSION

Our results indicate the involvement of HSP47 in the progression of peritoneal fibrosis and that inhibition of HSP47 expression might merit further clinical investigation for the treatment of peritoneal fibrosis in CAPD patients.

Detection of nuclear factor-kappaB in IgA nephropathy using Southwestern histochemistry

BACKGROUND

The transcription factor nuclear factor-kappaB (NF-kappaB) is involved in inflammatory and immune responses through induction of various cytokines and growth factors. The aim of this study is to examine the correlation between NF-kappaB expression and severity of tissue injury in immunoglobulin A (IgA) nephropathy and the mechanism of such correlation.

METHODS

The study included 43 renal tissue samples from 28 patients, including 28 samples of IgA nephropathy, 5 samples of non-IgA mesangial proliferative glomerulonephritis (non-IgA nephropathy), and 10 samples with nonproliferative glomerulonephritis (membranous nephropathy [MN] n = 5; minimal change nephrotic syndrome [MCNS]; n = 5). Tissue sections were examined by Southwestern histochemistry and immunohistochemistry for monocyte chemoattractant protein-1 (MCP-1), granulocyte-macrophage colony-stimulating factor (GM-CSF), and intercellular cell adhesion molecule-1 (ICAM-1), which are regulated by NF-kappaB. Normal portions of surgically resected kidney with adenocarcinoma served as controls.

RESULTS

In normal kidney, MCNS, and MN sections, NF-kappaB expression was detected in a few mesangial cells and tubular epithelial cells. In IgA nephropathy and non-IgA nephropathy samples, NF-kappaB was expressed in mesangial, glomerular endothelial and epithelial cells, tubular epithelial cells, and infiltrating cells. Expression in both glomeruli and interstitium correlated with progression of tissue injury. In IgA nephropathy samples, MCP-1 and GM-CSF expression was increased in both glomeruli and interstitium and correlated with progression of tissue injury. Glomerular ICAM-1 expression was weaker in severe lesions, whereas interstitial expression correlated with progression of tissue injury.

CONCLUSION

Our results indicate that NF-kappaB is involved in the progression of tissue injury in IgA nephropathy through the induction of transcriptionally regulated genes.

Intervention by retinoic acid in oxidative stress-induced apoptosis

Retinoic acid (RA) has been considered a pro-apoptotic agent, and little is known about its anti-apoptotic potential. In this article, we describe that RA strongly inhibits hydrogen peroxide (H(2)O(2))-induced apoptosis of mesangial cells by intervention in activator protein 1 (AP-1). Our data showed that: (i) H(2)O(2) induces apoptosis of mesangial cells via the AP-1 pathway; (iii) activation of AP-1 by H(2)O(2) is mediated by the c-Jun N-terminal kinase (JNK)-c-Jun/AP-1 pathway and the extracellular signal-regulated kinase-c-Fos/AP-1 pathway; (iii) RA inhibits H(2)O(2)-induced apoptosis via suppression of c-fos/c-jun expression and JNK activation; and (iv) the anti-apoptotic effect of RA is, at least in part, mediated by induction of mitogen-activated protein kinase phosphatase 1.

Transcriptional induction of mitogen-activated protein kinase phosphatase 1 by retinoids. Selective roles of nuclear receptors and contribution to the antiapoptotic effect

All-trans-retinoic acid (t-RA) inhibits hydrogen peroxide (H(2)O(2))-induced apoptosis by inhibiting the c-Jun N-terminal kinase (JNK)-activator protein 1 (AP-1) pathway. In this report, we examined the involvement of mitogen-activated protein kinase phosphatase 1 (MKP-1) in suppression of JNK and the antiapoptotic effect of t-RA and the roles of nuclear receptors in the regulation of MKP-1 by t-RA. We found that not only t-RA, but also a selective agonist of retinoic acid receptor (RAR), a selective agonist of retinoid X receptor (RXR), and a pan-agonist of RAR and RXR all induced MKP-1 at the transcriptional level. Activation of RAR was required for all of these triggering effects, but activation of RXR was required only for the RXR agonist-induced MKP-1 expression. Among the three RAR subtypes, RARalpha and RARgamma, but not RARbeta, mediated the t-RA-induced MKP-1 expression. The antiapoptotic effect of t-RA on H(2)O(2)-induced apoptosis in several cell types was correlated with the inducibility of MKP-1 by t-RA. Inhibition of MKP-1 by vanadate enhanced JNK phosphorylation and attenuated the antiapoptotic effect of t-RA. Furthermore, overexpression of MKP-1 inhibited H(2)O(2)-induced JNK phosphorylation and apoptosis. To our knowledge, this is the first to demonstrate that 1) MKP-1 is inducible by retinoids at the transcriptional level, 2) RXR and individual RAR subtypes have different roles in this process, and 3) the induced MKP-1 plays a significant role in mediating both JNK inhibition and the antiapoptotic effect of t-RA in oxidative stress.

Glomerulocystic kidney disease (GCKD) associated with Henoch-Schoenlein purpura: a case report and a review of adult cases of GCKD

We report on a 71-year-old male with Henoch-Schoenlein purpura (HSP) who developed glomerulocystic kidney disease (GCKD) without congenital abnormality. He had mild renal dysfunction. Renal biopsy findings showed mild proliferation of mesangial cells and matrixes, and tubular atrophy, interstitial fibrosis, cystic dilation of Bowman's capsule and atrophy of the glomerular tuft. The deposition of IgA and C3 in the mesangial area was observed with the fluorescent antibody technique. Therefore he was diagnosed with GCKD-associated HSP. This was the oldest patient among the previous case reports and the patient was the first case to be reported for concurrent GCKD and HSP. In this study, we also reviewed the patient to previously reported adult patients with GCKD.

Unexpected transcriptional induction of monocyte chemoattractant protein 1 by proteasome inhibition: involvement of the c-Jun N-terminal kinase-activator protein 1 pathway

Proteasome inhibitors, the well-known inhibitors of NF-kappaB, are recently considered therapeutic agents for inflammation. However, the anti-inflammatory properties of these agents have not been fully evaluated. In this report we describe a novel effect of proteasome inhibitors on the expression of monocyte chemoattractant protein 1 (MCP-1) in mesangial cells. We found that proteasome inhibitor MG132 dose-dependently induced expression of MCP-1 at the transcriptional level. The stimulatory effect was similarly observed with other proteasome inhibitors (proteasome inhibitor 1 and lactacystin) and in other cell types (NRK fibroblasts). The 5'-flanking region of the MCP-1 gene contains multiple AP-1 sites. To explore the mechanisms involved, we examined the effects of proteasome inhibition on the AP-1 pathway. Northern blot analysis showed that MG132 rapidly induced the expression of c-jun, but not c-fos. Immunoblot analysis showed that MG132 prevented degradation of c-Jun protein. Kinase assay revealed that c-Jun N-terminal kinase (JNK) was rapidly activated by MG132. Consistent with these results, a reporter assay showed that AP-1 activity was up-regulated after treatment with MG132. Curcumin, a pharmacological inhibitor of the JNK-AP-1 pathway, abrogated the induction of MCP-1 by MG132. Similarly, stable transfection with a dominant-negative mutant of c-Jun attenuated both MG132-induced activation of AP-1 and expression of MCP-1. The transcriptional activation by proteasome inhibitors was observed not only in MCP-1, but also in other AP-1-dependent genes, including stromelysin and mitogen-activated protein kinase phosphatase 1. These data revealed that proteasome inhibition triggered the expression of MCP-1 and other genes via the multistep induction of the JNK-c-Jun/AP-1 pathway.

Expression, regulation, and function of inhibitor of apoptosis family genes in rat mesangial cells

BACKGROUND

The inhibitor of apoptosis (IAP) family of proteins regulates programmed cell death triggered by various stimuli. The purpose of this investigation was to examine the expression, regulation, and function of IAP genes in cultured rat mesangial cells.

METHODS

Basal and inducible expression of c-IAP1, c-IAP2, XIAP, and TIAP mRNAs was examined in mesangial cells, isolated glomeruli, and other cell lines under unstimulated and tumor necrosis factor-alpha (TNF-alpha)-stimulated conditions. To examine a role of nuclear factor-kappa B (NF-kappa B) in the regulation of IAPs, expression of IAPs in NF-kappa B-inactive mesangial cells was compared with that in wild-type cells. To investigate roles of IAPs in mesangial cell apoptosis, NF-kappa B--inactive cells were stably supertransfected with c-IAP1 or c-IAP2, and the susceptibility of these cells to TNF-alpha--induced apoptosis was evaluated quantitatively.

RESULTS

Substantial, constitutive expression of c-IAP2, XIAP, and TIAP was observed in serum-deprived rat mesangial cells and c-IAP2 and XIAP in isolated normal rat glomeruli. In response to TNF-alpha, expression of c-IAP1 and c-IAP2 was induced in HeLa cells and ECV304 endothelial cells, but not in mesangial cells. In contrast to previous reports on other cell types, the expression of IAPs in rat mesangial cells was independent of NF-kappa B; that is, expression levels of IAPs in NF-kappa B--inactive cells were same as those in NF-kappa B--active cells under both unstimulated and TNF-alpha--stimulated conditions. Even without the induction of IAPs, NF-kappa B--active mesangial cells were more resistant to TNF-alpha--induced apoptosis than NF-kappa B--inactive cells. Interestingly, overexpression of either c-IAP1 or c-IAP2 completely compensated for the lack of resistance to apoptosis in NF-kappa B--inactive cells.

CONCLUSIONS

IAPs are constitutively expressed in cultured rat mesangial cells and isolated normal rat glomeruli. IAPs can contribute to the survival of rat mesangial cells, but unexpectedly, these molecules are not involved in the TNF-alpha--induced, NF-kappa B--dependent cytoprotection in this cell type.

Enhanced expression of complement C5a receptor mRNA in human diseased kidney assessed by in situ hybridization

BACKGROUND

Anaphylatoxin C5a mediates inflammatory responses through interaction with a specific C5a receptor (C5aR), the expression of which is thought to be restricted to peripheral blood leukocytes. Although the presence of C5aR on cultured mesangial cells and tubular epithelial cells has recently been documented, the tissue distribution of C5aR in diseased kidney has not yet been determined.

METHODS

Immunohistochemistry and nonradioactive in situ hybridization for C5aR were performed in 34 tissue samples of kidneys from patients with various renal diseases, including 4 with minimal change nephrotic syndrome (MCNS), 5 with membranous nephropathy (MN), and 25 with mesangial proliferative glomerulonephritis (mesGN; 15 patients with IgA nephropathy, 5 with non-IgA mesGN, and 5 with lupus nephritis). Normal portions of surgically resected kidney served as the control.

RESULTS

In normal kidneys, C5aR protein was detected in tubular epithelial cells, while C5aR mRNA was detected in a few glomerular cells, tubular epithelial cells, and vascular endothelial and smooth muscle cells. In MCNS, the distribution of C5aR protein and mRNA was similar to that in normal kidneys. In MN and mesGN, C5aR protein and mRNA were detected in mesangial cells, glomerular epithelial and endothelial cells, Bowman's capsule cells, tubular cells, infiltrating cells, and vascular endothelial and smooth muscle cells. The glomerular expression of C5aR mRNA and protein correlated positively with the degree of mesangial hypercellularity and mesangial matrix expansion in mesGN. In the tubulointerstitium, interstitial expression of C5aR mRNA correlated positively with the degree of tubular atrophy and interstitial broadening in mesGN. Furthermore, the interstitial expression of C5aR mRNA correlated positively with the level of serum creatinine.

CONCLUSIONS

Our results indicate that renal cells produce C5aR and that activation of C5a/C5aR pathway on renal cells may be involved in tissue injury in mesGN.

Selective roles of retinoic acid receptor and retinoid x receptor in the suppression of apoptosis by all-trans-retinoic acid

Retinoic acids exert profound effects on many biological processes including cell proliferation, differentiation, and morphogenesis. We previously reported that all-trans-retinoic acid (t-RA) protected mesangial cells from H(2)O(2)-triggered apoptosis by suppressing the activator protein 1 (AP-1) pathway. It was via inhibition of c-fos and c-jun expression and suppression of c-Jun N-terminal kinase (JNK) activation. In this report, we investigated the involvement of retinoic acid receptor (RAR) and retinoid X receptor (RXR) in the antiapoptotic effect of t-RA in H(2)O(2)-exposed cells. We found that pretreatment with RAR pan-antagonist (AGN193109) or RXR pan-antagonist (HX531) attenuated the antiapoptotic effect of t-RA. Similarly, transient transfection with a dominant-negative mutant of RAR or a dominant-negative RXR diminished the antiapoptotic effect of t-RA. Both RAR and RXR antagonists reversed the suppressive effect of t-RA on AP-1 activity. However, the roles of RAR and RXR in the suppression of AP-1 components by t-RA were found to be different. RAR antagonist reversed the suppressive effect of t-RA on both c-fos and c-jun, whereas RXR antagonist reversed the effect of t-RA on c-fos but not c-jun. Furthermore, suppression of JNK activation by t-RA was observed even in the presence of RAR and RXR antagonists. Consistently, suppression of JNK by t-RA was not affected by overexpression of either the dominant-negative RAR or the dominant-negative RXR. These data elucidated that the antiapoptotic effect of t-RA is mediated by both nuclear receptor-dependent and -independent mechanisms.

Suppression of constitutive but not Il-1beta-inducible expression of monocyte chemoattractant protein-1 in mesangial cells by retinoic acids: intervention in the activator protein-1 pathway

Retinoic acid regulates a wide range of biologic processes, including inflammation. This study investigated the effect of all-trans-retinoic acid (t-RA) on the constitutive and cytokine-inducible expression of monocyte chemoattractant protein 1 (MCP-1) in rat mesangial cells. Serum-deprived mesangial cells exhibited substantial levels of MCP-1 mRNA, and the expression was markedly upregulated by interleukin-1beta (IL-1beta). Pretreatment with t-RA abrogated the constitutive mRNA expression but did not inhibit the IL-1beta-inducible expression. The similar effects were observed by 9-cis-RA. The suppressive effect of t-RA required retinoic acid receptors. t-RA did not affect the stability of MCP-1 mRNA, indicating that its suppressive effect was at the transcriptional level. Experiments that used pharmacologic and genetic inhibitors showed that the IL-1beta-inducible MCP-1 expression was dependent on nuclear factor-kappaB (NF-kappaB) and independent of activator protein 1 (AP-1). In contrast, the constitutive expression of MCP-1 was dependent on both NF-kappaB and AP-1. t-RA substantially inhibited the constitutive activity of AP-1 but did not inhibit NF-kappaB activity in mesangial cells. These data suggested that (1) constitutive and IL-1beta-inducible expression of MCP-1 was differently regulated by AP-1 and NF-kappaB and (2) t-RA inhibited selectively the constitutive expression of MCP-1 via intervention in the AP-1 pathway.