The role of mammalian target of rapamycin pathway in the pathogenesis of pauci-immune glomerulonephritis.

Background: The characteristic lesion of pauci-immune glomerulonephritis is focal necrotizing and crescentic glomerulonephritis. The underlying mechanisms in the formation or progression of crescent formation need further investigations. Therefore, we aimed to evaluate the role of mammalian target of rapamycin (mTOR), which might be a potential therapeutic target, in kidney biopsies of patients with pauci-immune glomerulonephritis. Methods: The patients diagnosed as pauci-immune glomerulonephritis at an outpatient nephrology clinic were retrospectively reviewed and those patients who had a kidney biopsy before receiving an immunosuppressive treatment were included in the study. Kidney biopsy specimens were immunohistochemically stained with mTOR, antibodies of phosphatase and tensin homolog (PTEN) and transforming growth factor-ß (TGF-ß) and scored by an experienced renal pathologist. Results: In total, 54 patients with pauci-immune glomerulonephritis (28 [52%] female) were included. According to the histopathologic examination, 22% of our cases were classified as focal, 33% crescentic, 22% mixed, and 22% as sclerotic. The mTOR was expressed in substantial percentages of glomeruli of patients with pauci-immune glomerulonephritis. However, we observed PTEN expression in all samples and mTOR in all tubulointerstitial areas. mTOR expression was found to be related with the presence of crescentic and sclerotic changes observed in glomeruli and the degree of fibrosis in interstitial areas. Serum creatinine level or response to treatment was not found to be associated with mTOR pathway expression. Conclusion: Our results suggest that mTOR pathway may play role in the pathogenesis of pauci-immune glomerulonephritis, besides targeting this signaling may be an alternative option for those patients.

Prognostic value of glomerular C4d staining in patients with IgA nephritis.

INTRODUCTION: Mesangial IgA deposition is the initiative factor in the pathogenesis of IgA nephropathy (IgAN). Glomerular IgA depositon leads to activation local complement system. C4d positivity shows that complement activation occurs via alternative pathway. C4d positivity at the time of renal biopsy can be associated with poor prognosis in IgA nephropathy. We aimed to evaluate C4d deposition and renal outcome in patients with IgA nephritis. METHODS: Between January 2005 and December 2009, 40 patients with IgA nephritis were enrolled. Renal biopsy specimens of 33 patients have been evaluated. C4d immunohistochemical staining was performed 3-µm deparaffinized and rehydrated sections of formaldehyde-fixed renal tissues, using rabbit polyclonal anti-human C4d as the antibody. Baseline demographical, clinical and laboratory data were recorded retrospectively. RESULTS: Mean age of the patients was 35.9 ± 12.9 years and female/male ratio was 19/21. Mean duration of follow-up was 32.8 (12-60) months. Baseline glomerular filtration ratio (GFR) and proteinuria were 55.8 ml/min and 2.44 gr/day respectively at the time of renal biopsy. Eleven patients were C4d positive. Presence of hypertension (p=0.133), proteinuria (p=0.007), serum creatinine levels (p=0.056) and glomerulosclerosis (p=0.004), mesengial hypersellularity (p=0.0001) and interstitial fibrosis (p=0.006) at the time of renal biopsy were higher in C4d positive group rather than negative group. Evolution to renal failure were 63.6% in C4d positive group and 13.6% in negative group (p=0.006). Renal survival at 3 years was 39% in C4d-positive patients versus 66.7% in the C4d-negative patients (log rank- p=0.0072).

Quantitative evaluation of interstitial fibrosis with Sirius Red in IgA nephritis.

OBJECTIVE: Tubulointerstitial fibrosis is one of the strongest independent predictive factors in determining the prognosis in IgA nephritis. Recently, software-based quantitative measurement of interstitial fibrosis with Sirius Red staining has entered the practice. The objective of this study was to investigate the prognostic value of measurement of interstitial nephritis with this method in IgA nephritis. METHOD: Forty-three patients diagnosed with IgA nephritis with renal biopsy between the years 2005 and 2009 were included in this retrospective observational study. The diagnostic biopsies of 37 patients were examined. Basal data included age, gender, creatinine level, glomerular filtration rate (GFR), presence of proteinuria, hypertension, glomerulosclerosis, mesangial proliferation, and interstitial fibrosis and fibrosis index calculated by the measurement of computed images of Sirius Red positive areas. Final visit included evaluation of development of end-stage renal disease (ESRD), and GFR (whether = 60 mL/min or <60 mL/min). RESULTS: Numbers of patients with hypertension (75% vs. 34.5%; p = 0.050), ESRD development (62.5% vs. 20.7%, p = 0.035), GFR <60 mL/min (87.5% vs. 31%; p = 0.007) were greater; and basal GFR (34.25 ± 25.29 vs. 64.14 ± 35.34; p = 0.048) was lower in high-intensity interstitial fibrosis group (>1000 µm2) compared to low-intensity interstitial fibrosis group (≤1000 µm(2)). CONCLUSION: Quantitative analysis of computed imaging of areas of Sirius Red positive tubulointerstitial fibrosis might serve as an effective novel method to determine the prognosis in IgA nephritis.

Prognostic value of NGAL staining in patients with IgA nephropathy.

BACKGROUND: Renal tubulointerstitial injury plays an important role in disease progression of IgAN. Neutrophil gelatinase-associated lipocalin (NGAL) is a stress protein released by tubular cells. NGAL is a promising biomarker of acute kidney injury. There is a growing literature suggesting that NGAL is also a marker of chronic kidney disease and severity. Our aim was to evaluate the prognostic value of NGAL staining in patients with IgAN. METHODS: This retrospective study included all consecutive patients who underwent a renal biopsy at our center between January 2005 and December 2009. Forty-five patients with IgA nephritis were enrolled, and renal biopsy specimens of 29 patients were evaluated. We evaluated baseline age, sex, hypertension, serum creatinine, glomerular filtration rate (GFR), urine protein, NGAL staining, glomerulosclerosis, interstitial fibrosis, and extracapillary proliferation. The primary endpoint of this study was doubling of baseline serum creatinine and/or the onset of ESRD in the course of the study. At the end of the follow-up, patients whose estimated GFR (eGFR) was ≤15 mL/min/1.73 m(2) and/or baseline serum creatinine doubled, were defined as the progressor group. RESULTS: Nineteen patients (65.5%) were NGAL positive and 10 patients (34.5%) were NGAL negative. Female gender and hypertension were associated with NGAL-positive staining. Urinary protein excretion and serum creatinine levels were more elevated in the NGAL-positive group, but the difference was not significant. We found NGAL-positive staining in major proportion in the progressor group (88.9%) than the non-progressor group (55%) (p = 0.076). CONCLUSION: NGAL staining can be a new histological marker in IgAN progression.

Glomerular c4d staining can be an indicator of disease activity in lupus nephritis.

BACKGROUND: Abnormalities in complement activation and clearance of immune complexes by erythrocytes are the central pathogenic mechanisms in systemic lupus erythematosus (SLE). Serum C4d level, which is a degradation product of complement factor C4, was found to be a sensitive indicator of SLE activity. Our aim was to determine whether glomerular C4d staining could be a useful marker of disease activity in patients with lupus nephritis. METHODS: This retrospective study included all consecutive patients who underwent a renal biopsy at our center between January 2005 and December 2009. A total of 29 patients with IgA nephritis were enrolled, and renal biopsy specimens of 24 patients have been evaluated. We evaluated baseline age, sex, hypertension, serum creatinine level, glomerular filtration rate (GFR), urine protein, and glomerular C4d staining. The primary endpoint of this study was the onset of end-stage renal disease (ESRD) in the course of study. RESULTS: Fourteen (58%) patients were C4d+ and 10 (42%) patients C4d-. Urinary protein excretion was more elevated in C4d+ group (p = 0.0001). The renal biopsy showed that activity index score >12 was a higher proportion in C4d+ patients. The patients were followed up for 3.5 years. Four patients in the C4d+ group evolved to ESRD in the follow-up, but none of the patients in the C4d- group (p = 0.064). DISCUSSION: We found a relationship between glomerular C4d staining and activity of lupus nephritis. C4d staining may be a useful marker to predict the prognosis of lupus nephritis.

TLR polymorphisms in FMF: association of TLR-2 (Arg753Gln) and TLR-4 (Asp299Gly, Thre399Ile) polymorphisms and myeloid cell TLR-2 and TLR-4 expression with the development of secondary amyloidosis in FMF.

Amyloidosis is the major complication of familial Mediterranean fever (FMF). Toll-like receptors (TLR) are involved in the activation of an innate immune system TLR-2 and TLR-4 recognize lipoteichoic acid and lipopolysaccharides (LPS), respectively. While TLR-2 Arg753Gln polymorphism upregulates, TLR-4 Asp299Gly and Thre399Ile polymorphisms downregulate inflammation. We investigated the effect of these polymorphisms on the development of amyloidosis in FMF patients. We also investigated myeloid cell TLR-2 and TLR-4 expressions in these patients. We studied 26 FMF patients and 13 FMF patients with amyloidosis. TLR-2 Arg753Gln and TLR-4 Asp299Gly and Thr399Ile polymorphisms were analyzed with the polymerase chain reaction-restriction fragment length polymorphism method. Myeloid cell baseline TLR-2 and TLR-4 and LPS-induced TLR-4 expressions were evaluated. The TLR-2 and TLR-4 polymorphism rate was compared with the results of 100 healthy subjects in our previous study. In addition, 13 healthy controls were enrolled for leukocyte TLR-2 and TLR-4 expressions. Serum amyloid A (SAA) levels were measured in these 13 control cases and in FMF patients during attack-free periods. The frequency of TLR-2 Arg753Gln, TLR-4 Asp299Gly, and Thr399Ile polymorphisms in healthy controls in our previous study were 1%, 3%, and 2%, respectively. The frequency of these polymorphisms were not different in FMF patients (with or without amyloidosis) compared to the control group. Likewise, myeloid cell TLR-2 and TLR-4 expressions were not different among the controls and FMF patients. However, LPS-induced TLR-4 expression in granulocytes was more prominent in FMF patients. There was no correlation between TLR-2 and TLR-4 expressions and SAA levels. Neither myeloid cell TLR-2 and TLR-4 expressions nor TLR-2 Arg753Gln, TLR-4 Asp299Gly, and Thr399Ile polymorphisms seem to affect the development of secondary amyloidosis in FMF patients in our study population.

Preventive effect of nebivolol on contrast-induced nephropathy in rats.

BACKGROUND: Altered renal vasodilatation and oxidative stress are important mechanisms of contrast-induced nephropathy (CIN). The aim of the present study was to assess the effect of nebivolol, a beta blocker, on prevention of CIN. We hypothesized that nebivolol may prevent CIN due to its renal vasodilatation and antioxidant effects. METHODS: Thirty-two Wistar-albino rats were divided into four groups (n = 8 each): control (C), contrast media (CM), nebivolol (N), and nebivolol + contrast media (NCM). CIN was induced by administration of intravenous high-osmolar contrast media diatrizoate (6 ml/kg) after 72 h of dehydration. Nebivolol (2 mg/kg) was given internally once daily for 5 days. Kidney function parameters, nitric oxide metabolites and oxidative stress markers were measured. Kidneys were excised for pathological evaluation. RESULTS: The decrease of creatinine clearance was 0.180 +/- 0.11 mg/dl in CM, and 0.030 +/- 0.10 mg/dl in NCM (P = 0.01). Microproteinuria was ameliorated using nebivolol (P = 0.001). Serum protein carbonyl content, malonyldialdehyde and kidney thiobarbituric acid-reacting substances levels were higher in CM than in C (P = 0.003, P < 0.001 and P = 0.034, respectively) and serum thiol was lower in CM than in C (P = 0.001). However, oxidative stress markers were similar in NCM and C. Diatrizoate decreased kidney nitrite levels, but nebivolol increased them (P = 0.027). Nebivolol attenuated the tubular necrosis, proteinaceous casts and medullary congestion, although significant protective effects, were observed in tubular necrosis (P = 0.001) and proteinaceous cast (P < 0.001). CONCLUSION: This study demonstrated the protective role of nebivolol against CIN.

An unusual vascular involvement in a patient with Behcet's disease: renal artery stenosis.

Behcet's disease (BD) is a rare multisystem inflammatory disorder characterized by recurrent ulcers affecting the mouth and genitals, various skin lesions, relapsing iritis, and vasculitis. Vascular events may dominate the clinical presentation in some patients with BD. Hitherto three forms of vascular disease such as venous occlusions, arterial aneurysms, and arterial occlusions have been reported in BD. Renal vascular involvement has reported in less than 1% of the patients with vascular BD. A case of BD with renovascular hypertension is reported. To our knowledge, a case of BD with renovascular hypertension treated with angioplasty and stent implantation has not been reported previously.

The effects of irbesartan and spironolactone in prevention of peritoneal fibrosis in rats.

BACKGROUND: Bacterial peritonitis episodes may disturb the functional and histological integrity of the peritoneum in peritoneal dialysis patients. The renin-angiotensin-aldosterone system may have fibrotic effects on the peritoneum. OBJECTIVE: To study the effects of an angiotensin II receptor antagonist (irbesartan) and an aldosterone antagonist (spironolactone) in the prevention of peritoneal fibrosis in a rat model of bacterial peritonitis. METHODS: 40 Wistar rats were randomized into 5 groups: bacteria (B), bacteria-irbesartan (BI), bacteria-spironolactone (BS), bacteria-irbesartan-spironolactone (BIS), and control (C) groups. The C group received only dextran beads (Cytodex; Sigma Chemicals, St Louis, Missouri, USA); the others were given bacteria and dextran beads intraperitoneally. Irbesartan and/or spironolactone were given to 3 groups: BI, BS, and BIS. On the eighth day, the rats were sacrificed, peritoneal adhesion was quantified, and peritoneal tissue sections were evaluated histologically. RESULTS: The peritoneal total adhesion score was significantly higher in the B group than in the BI, BIS, and C groups (p < 0.01). Mean peritoneal thickness, mean inflammation score, and mean fibrosis score were significantly higher in the B group in comparison to the C group (p < 0.05). Mean peritoneal thickness of all treatment groups was significantly lower than the B group (p < 0.05). Serum transforming growth factor beta-1 level was significantly higher in the B group than in the BI, BS, and C groups (p < 0.05). CONCLUSION: Irbesartan and spironolactone seem to decrease the extent of peritoneal injury caused by bacterial peritonitis.

Impact of diabetic and pre-diabetic state on development of contrast-induced nephropathy in patients with chronic kidney disease.

BACKGROUND: The aim of the present study was to assess the influence of diabetic and pre-diabetic state on the development of contrast-induced nephropathy (CIN) in chronic kidney disease patients undergoing coronary angiography. METHODS: A total of 421 patients with Cockcroft clearance between 15 and 60 ml/min were divided into three groups [diabetes mellitus (DM), n = 137; pre-diabetes (pre-DM), n = 140; and normal fasting glucose (NFG), n = 144]. CIN was defined as an increase of > or =25% in creatinine over baseline within 48 h of angiography, DM as glucose > or =126 mg/dl, pre-DM as glucose between 100 and 125 mg/dl and NFG as glucose <100 mg/dl. RESULTS: CIN occurred in 20% of the DM [relative risk (RR) 3.6, P = 0.001], 11.4% of the pre-DM (RR 2.1, P = 0.314) and 5.5% of the NFG group. The decrease of glomerular filtration rate (GFR) was higher in DM and pre-DM (P = 0.001 and P = 0.002, respectively). GFR < or =30 ml/min (RR 19.22), multivessel involvement (RR 7.59), hyperuricaemia (RR 3.95), use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blocker (RR 2.70) and DM (RR 2.34) were predictors of CIN. Length of hospital stay was 2.45 +/- 1.45 day in DM, 2.27 +/- 0.68 day in pre-DM and 1.97 +/- 0.45 day in NFG (P < 0.001, DM vs NFG and P = 0.032, pre-DM vs NFG). The rate of major adverse cardiac events was 8.7% in DM, 5% in pre-DM and 2.1% in NFG (P = 0.042, DM vs NFG). Haemodialysis was required in 3.6% of DM and 0.7% in pre-DM (P = 0.036, DM vs NFG), and the total number of haemodialysis sessions during 3 months was higher in DM and pre-DM (P < 0.001). Serum glucose > or =124 mg/dl was the best cut-off point for prediction of CIN. CONCLUSION: Our data support that patients with DM are at a higher risk of developing CIN, but patients with pre-DM are not at as high a risk for developing CIN as diabetes patients.

Reflex sympathetic dystrophy syndrome due to arteriovenous fistula.

A patient with end-stage renal disease presented with reflex sympathetic dystrophy syndrome (RSDS) on her left hand 1 month after arteriovenous fistula (AVF) surgery. Magnetic resonance angiography revealed steal syndrome at the AVF level. Bone scintigraphy revealed early-stage RSDS. We considered that arterial insufficiency because of steal phenomenon following AVF surgery and underlying occlusive arterial disease triggered RSDS development.

The effects of weekly mupirocin application on infections in continuous ambulatory peritoneal dialysis patients.

Application of mupirocin to the nares or catheter exit site and frequency of mupirocin administration in continuous ambulatory peritoneal dialysis (CAPD) patients remain controversial. The objective of our study was to evaluate, using a historical control group, the efficacy on CAPD-related infections of once-weekly application of mupirocin at the catheter exit site. We instructed 18 CAPD patients, who did not initially use prophylactic antibiotic treatment, about once-weekly application of mupirocin ointment to the exit site as part of their exit-site care. We recorded the incidence of catheter-related infections, the causative micro-organisms, and the rate of catheter loss. We observed 17 acute exit-site infections (AESIs: 0.45 episodes/patient-year) before mupirocin treatment and 2 AESIs (0.06 episodes/patient-year) after treatment. The relative rate of AESI reduction was 86%. Before application of mupirocin, 52% of AESIs were attributable to Staphylococcus-aureus; after mupirocin administration, no AESIs were staphylococcal. Peritonitis episodes were also reduced from 21 before mupirocin treatment (0.56 episodes/patient-year), to 9 after mupirocin administration (0.29 episodes/patient-year). The relative rate of peritonitis reduction was 48%. Once-weekly application of mupirocin to the exit site resulted in a reduction in exit-site infections and peritonitis episodes comparable to those obtained with daily application.