Acute Phosphate Nephropathy with Diffuse Tubular Injury Despite Limited Calcium Phosphate Deposition.

An 86-year-old woman developed acute kidney injury after colonoscopy. A renal biopsy showed diffuse tubular injury with minimal calcium phosphate deposits (CPDs), which were thought to be caused by an oral sodium phosphate bowel purgative before colonoscopy. According to these findings, she was diagnosed with acute phosphate nephropathy (APhN). In contrast to previous reports of diffuse tubular injury associated with tubular CPDs in APhN, this case demonstrated diffuse tubular injury despite a limited distribution of CPDs, suggesting that calcium phosphate can cause tubular injury without deposition. This case thus supports the hypothesis that urinary calcium phosphate crystals may cause tubular injury via other mechanisms, including inflammatory cytokines.

A case of podocytic infolding glomerulopathy with multiple myeloma.

BACKGROUND: Podocytic infolding glomerulopathy (PIG) is a recently described condition causing rare pathological changes to the glomeruli, and has attracted considerable attention. PIG is characterized by specific changes to the thickened glomerular basement membrane (GBM), including microspheres, microtubular structures, and podocytic infolding. Only a small number of cases of PIG have been reported. The clinical features and pathogenesis of this condition are still unclear. To elucidate the characteristics of this glomerulopathy, it is necessary to accumulate information from reported cases. We present here the first reported case of PIG with multiple myeloma. CASE PRESENTATION: A 79-year-old Japanese man was admitted to his local hospital with proteinuria, hypergammaglobulinemia, hypoalbuminemia, and kidney dysfunction. Laboratory tests revealed monoclonal IgG(λ) M proteins in the serum and Bence-Jones proteins in the urine. Bone marrow aspiration showed monoclonal plasma cell proliferation, indicating a diagnosis of multiple myeloma. Renal biopsy was performed to determine the cause of the proteinuria and kidney dysfunction. Histological examination of the biopsy specimen showed glomeruli with an irregularly thickened GBM and bubble-like structures in the capillary walls. Immunofluorescence staining did not show glomerular deposition of immunoglobulins, light chains, or complement components. Congo red staining did not show amyloid deposition. Electron microscopy showed an irregularly thickened GBM with unusual structures in the glomerular capillary walls including podocytic infolding and microspheres, suggesting PIG. There were no electron-dense deposits in the GBM, while various findings indicating podocyte injury were detected. CONCLUSION: We present here the first reported case of PIG in a patient with multiple myeloma. The mechanisms underlying the development of PIG in multiple myeloma are unknown, but may be associated with podocyte injury.

PPARα Activation Protects against Anti-Thy1 Nephritis by Suppressing Glomerular NF-κB Signaling.

The vast increase of chronic kidney disease (CKD) has attracted considerable attention worldwide, and the development of a novel therapeutic option against a representative kidney disease that leads to CKD, mesangial proliferative glomerulonephritis (MsPGN) would be significant. Peroxisome proliferator-activated receptor α (PPARα), a member of the steroid/nuclear receptor superfamily, is known to perform various physiological functions. Recently, we reported that PPARα in activated mesangial cells exerted anti-inflammatory effects and that the deficiency of PPARα resulted in high susceptibility to glomerulonephritis. To investigate whether PPARα activation improves the disease activity of MsPGN, we examined the protective effects of a PPARα agonist, clofibrate, in a well-established model of human MsPGN, anti-Thy1 nephritis, for the first time. This study demonstrated that pretreatment with clofibrate (via a 0.02% or 0.1% clofibrate-containing diet) continuously activated the glomerular PPARα, which outweighed the PPARα deterioration associated with the nephritic process. The PPARα activation appeared to suppress the NF-κB signaling pathway in glomeruli by the induction of IκBα, resulting in the reduction of proteinuria and the amelioration of the active inflammatory pathologic glomerular changes. These findings suggest the antinephritic potential of PPARα-related medicines against MsPGN. PPARα-related medicines might be useful as a treatment option for CKD.

Pretreatment by low-dose fibrates protects against acute free fatty acid-induced renal tubule toxicity by counteracting PPARα deterioration.

Development of a preventive strategy against tubular damage associated with proteinuria is of great importance. Recently, free fatty acid (FFA) toxicities accompanying proteinuria were found to be a main cause of tubular damage, which was aggravated by insufficiency of peroxisome proliferator-activated receptor alpha (PPARα), suggesting the benefit of PPARα activation. However, an earlier study using a murine acute tubular injury model, FFA-overload nephropathy, demonstrated that high-dose treatment of PPARα agonist (0.5% clofibrate diet) aggravated the tubular damage as a consequence of excess serum accumulation of clofibrate metabolites due to decreased kidney elimination. To induce the renoprotective effects of PPARα agonists without drug accumulation, we tried a pretreatment study using low-dose clofibrate (0.1% clofibrate diet) using the same murine model. Low-dose clofibrate pretreatment prevented acute tubular injuries without accumulation of its metabolites. The tubular protective effects appeared to be associated with the counteraction of PPARα deterioration, resulting in the decrease of FFAs influx to the kidney, maintenance of fatty acid oxidation, diminution of intracellular accumulation of undigested FFAs, and attenuation of disease developmental factors including oxidative stress, apoptosis, and NFκB activation. These effects are common to other fibrates and dependent on PPARα function. Interestingly, however, clofibrate pretreatment also exerted PPARα-independent tubular toxicities in PPARα-null mice with FFA-overload nephropathy. The favorable properties of fibrates are evident when PPARα-dependent tubular protective effects outweigh their PPARα-independent tubular toxicities. This delicate balance seems to be easily affected by the drug dose. It will be important to establish the appropriate dosage of fibrates for treatment against kidney disease and to develop a novel PPARα activator that has a steady serum concentration regardless of kidney dysfunction.

Granulomatous transformation of capillary lesions in pulmonary-renal syndrome autologously induced anti-glomerular basement membrane disease in Wistar-Kyoto rats.

BACKGROUND: Pulmonary-renal syndrome is characterized by pulmonary hemorrhage and rapidly progressive glomerulonephritis in various immunological states. Histopathological analysis of pulmonary-renal syndrome is not yet complete. METHODS: Wistar-Kyoto (WKY) rats were sensitized using the noncollagenous (NC1) domain of type IV collagen from bovine kidney as an antigen. Histopathology of the kidneys and lungs was investigated with light microscopy, immunohistochemistry and electromicroscopy. Expression levels of cytokine mRNA were determined by real-time RT-PCR using renal tissue of rats. RESULTS: Macrophage-rich granulomatous glomerulonephritis and alveolar capillaritis accompanied with pulmonary hemorrhage were induced by the sensitization. The humoral antibody against NC1 was detected on the glomerular and alveolar capillary walls. Th2 cytokine IL-10 was dominant over Th1 cytokine IFN-gamma in renal tissues of WKY rats. CONCLUSION: The granulomatous transformation seemed to be induced by macrophage conspicuous capillaritis under dominant cellular immune reactions in WKY rats. In addition to Th1 cytokines, Th2 cytokines may also participate in the formation of granulomatous lesions.

Kidney dysfunction induced by protein overload nephropathy reduces serum sulfatide levels in mice.

We recently proposed serum sulfatides as a novel biomarker for cardiovascular disease in patients with end-stage renal failure (ESRF), based on the possible antithrombotic properties of this molecule. In this earlier study, the level of serum sulfatides was gradually decreased in parallel with kidney dysfunction; however the precise mechanism underlying this decrease was unknown. The aim of the present study was to investigate the mechanism underlying the decrease in serum sulfatide levels caused by kidney dysfunction in an experimental animal model. To produce a kidney dysfunction animal model, we prepared a mouse model of protein overload nephropathy. Using high-throughput analysis combined with matrix-assisted laser desorption ionisation time-of-flight mass spectrometry, we measured the levels of sulfatides in the sera, livers, small intestines and kidneys of protein overload nephropathy mice. As the disease progressed, the levels of sulfatides in sera decreased. Also, the levels in livers and small intestines decreased in a similar manner to those in sera, to approximately 60% of the original levels. On the contrary, those in kidneys increased by approximately 1.4-fold. Our results indicate that kidney dysfunction affects the levels of sulfatides in lipoprotein-producing organs, such as livers and small intestines, and lowers the levels of sulfatides in sera.

A nationwide survey of rapidly progressive glomerulonephritis in Japan: etiology, prognosis and treatment diversity.

BACKGROUND: The etiology, prevalence, and prognosis of rapidly progressive glomerulonephritis (RPGN) including renal vasculitis vary among races and periods. METHOD: To improve the prognosis of Japanese RPGN patients, we conducted a nationwide survey of RPGN in the nephrology departments of 351 tertiary hospitals, and found 1772 patients with RPGN (Group A: diagnosed between 1989 and 1998, 884 cases; Group B: diagnosed between 1999 and 2001, 321 cases; and Group C: diagnosed between 2002 and 2007, 567 cases). ANCA subclasses, renal biopsy findings, treatment, outcome and cause of death were recorded. RESULT: The most frequent primary disease was renal-limited vasculitis (RLV) (42.1%); the second was microscopic polyangiitis (MPA) (19.4%); the third was anti-GBM-associated RPGN (6.1%). MPO-ANCA was positive in 88.1% of RLV patients and 91.8% of MPA patients. The proportion of primary renal diseases of RPGN was constant during those periods. The most frequent cause of death was infectious complications. The serum creatinine at presentation and the initial dose of oral prednisolone decreased significantly in Groups B and C compared to Group A. However, both patient and renal survival rates improved significantly in Groups B and C (survival rate after six months in Group A: 79.2%, Group B: 80.1%, and Group C: 86.1%. Six-month renal survival in Group A: 73.3%, Group B: 81.3%, and Group C: 81.8%). CONCLUSION: Early diagnosis was the most important factor for improving the prognosis of RPGN patients. To avoid early death due to opportunistic infection in older patients, a milder immunosuppressive treatment such as an initial oral prednisolone dose reduction with or without immunosuppressant is recommended.

PPAR{alpha} attenuates the proinflammatory response in activated mesangial cells.

The activated mesangial cell is an important therapeutic target for the control of glomerulonephritis. The peroxisome proliferator-activated receptor alpha (PPARalpha) has attracted considerable attention for its anti-inflammatory effects; however, its roles in the mesangial cells remain unknown. To determine the anti-inflammatory function of PPARalpha in mesangial cells, wild-type and Ppara-null cultured mesangial cells were exposed to lipopolysaccharide (LPS). LPS treatment caused enhanced proinflammatory responses in the Ppara-null cells compared with wild-type cells, as revealed by the induction of interleukin-6, enhanced cell proliferation, and the activation of the nuclear factor (NF)-kappaB signaling pathway. In wild-type cells resistant to inflammation, constitutive expression of PPARalpha was undetectable. However, LPS treatment induced the significant appearance and substantial activation of PPARalpha, which would attenuate the proinflammatory responses through its antagonizing effects on the NF-kappaB signaling pathway. The induction of PPARalpha was coincident with the appearance of alpha-smooth muscle actin, which might be associated with the phenotypic changes of mesangial cells. Moreover, another examination using LPS-injected wild-type mice demonstrated the appearance of PPARalpha-positive cells in glomeruli, suggesting in vivo correlation with PPARalpha induction. These results suggest that PPARalpha plays crucial roles in the attenuation of inflammatory response in activated mesangial cells. PPARalpha might be a novel therapeutic target against glomerular diseases.

Proposal of podocytic infolding glomerulopathy as a new disease entity: a review of 25 cases from nationwide research in Japan.

BACKGROUND: A rare and peculiar glomerulopathy has begun to be recognized in Japan. The Japanese Society of Nephrology has established a research working group and has collected cases from all over Japan in an attempt to understand the complete spectrum of this glomerulopathy. METHOD: The diagnostic criterion, which was needed to collect the cases, was proposed as a glomerulopathy showing microspheres or microtubular structures or both associated with podocytic infolding into the glomerular basement membrane (GBM) on electron microscopy. The lesion shows a non-argentaffin hole in the GBM with periodic acid methenamine silver staining and is similar to membranous glomerulonephritis. RESULTS: Twenty-five cases were collected from 17 institutions. Patients were 20-69 years old (19 women, 6 men). Seventeen patients also had collagen diseases such as lupus nephritis and Sjögren's syndrome. All patients had proteinuria. Proteinuria showed a remission in 15 of 23 patients within 12 months, but proteinuria remained higher than 1.0 g/day in five patients despite different types of therapy. Podocytic infolding including microspheres showed either positive or negative staining for immunoglobulins. Cluster formation of microspheres was found in 4 of 17 patients with collagen disease, and in five out eight patients without collagen disease. Electron-dense deposits in the GBM were also found in 6 of 17 patients with collagen disease but were not found in eight patients without collagen disease. CONCLUSION: Some patients might have a subtype of lupus nephritis, class V, or membranous glomerulonephritis. However, we propose a new disease entity, podocytic infolding glomerulopathy, as a common basis of all 25 patients, because we suspect that microspheres or microtubular structures or both can be derived from podocytic infolding.

A nephrotic case of vesicoureteral reflux representing focal segmental glomerulosclerosis associated with podocytic infolding lesions.

The case was a 54-year-old woman who had suffered from occasional incontinence of urine after a craniotomy for subarachnoid hemorrhage in 1991. In June 1998 she was admitted for nephrotic syndrome without hematuria. Intravenous pyelography and voiding cystourethrography revealed bilateral hydronephrosis, atonic bladder, and vesicoureteral reflux (VUR). Renal biopsy demonstrated the presence of focal segmental glomerulosclerosis with cellular lesions. However, periodic-acid methenamine silver (PAM) staining revealed bubbling and spike appearance in the diffuse peripheral loops, although immunofluorescence microscopy showed negative findings in the glomeruli. Electron microscopy revealed diffuse thickening of the glomerular basement membrane (GBM) accompanying diffuse podocytic infolding lesions into the GBM and numerous spherical microstructures in the GBM. No findings of dense deposits were observed in the GBM and mesangium. Her urinary protein excretion decreased and renal function improved after placement of an urethral catheter for one year. A second renal biopsy revealed a remarkable decrease in podocytic infolding lesions, although microstructures in the GBM remained. Although mechanisms of the occurrence of these peculiar podocytic infolding lesions are unclear, it is speculated that podocyte damage due to hydronephrosis may have caused the lesions.

Renal pathology of ANCA-related vasculitis: proposal for standardization of pathological diagnosis in Japan.

BACKGROUND: In Japan, systematic evaluation of the histologic parameters of anti-neutrophil cytoplasmic autoantibodies (ANCA)-related vasculitis has been performed according to the Japanese classification by Shigematsu et al. However, this classification is quite different from that of the European Vasculitis Study Group (EUVAS) classification. Therefore, a histological common basis is needed to compare Japanese histological data with the international database. METHOD: Histological parameters concerning glomerular, tubulointerstitial, and vascular lesions of ANCA-related vasculitis, which are indispensable for clinical management, were elucidated and defined by reviewing, utilizing the merits of, and amending the two scoring systems. RESULTS AND CONCLUSION: A new comprehensive and standardized scoring system, by which histological quantitative assessment can provide evidence for therapy planning, has been developed for renal biopsy of Japanese ANCA-related vasculitis.

Peroxisome proliferator-activated receptor alpha protects against glomerulonephritis induced by long-term exposure to the plasticizer di-(2-ethylhexyl)phthalate.

Safety concerns about di-(2-ethylhexyl)phthalate (DEHP), a plasticizer and a probable endocrine disruptor, have attracted considerable public attention, but there are few studies about long-term exposure to DEHP. DEHP toxicity is thought to involve peroxisome proliferator-activated receptor alpha (PPARalpha), but this contention remains controversial. For investigation of the long-term toxicity of DEHP and determination of whether PPARalpha mediates toxicity, wild-type and PPARalpha-null mice were fed a diet that contained 0.05 or 0.01% DEHP for 22 mo. PPARalpha-null mice that were exposed to DEHP exhibited prominent immune complex glomerulonephritis, most likely related to elevated glomerular oxidative stress. Elevated NADPH oxidase, low antioxidant enzymes, and absence of the PPARalpha-dependent anti-inflammatory effects that normally antagonize the NFkappaB signaling pathway accompanied the glomerulonephritis in PPARalpha-null mice. The results reported here indicate that PPARalpha protects against the nephrotoxic effects of long-term exposure to DEHP.

Postinflammatory glomerular recanalization is established under the accommodation of transformed mesangial cells.

BACKGROUND: The relationship between mesangial cell proliferation and sclerosis has been studied using rat Thy-1.1 nephritis. The reconstruction of capillary lumina is essential for the repair of postinflammatory tissue damage in this type of glomerulonephritis. METHODS: We administered thalidomide or STI571 to Thy-1.1 nephritic rats. Thalidomide was intended to be a sup-pressor of capillary proliferation, and STI571, which is known to be a tyrosine kinase receptor inhibitor, was used for preventing mesangial proliferation. RESULTS: The thalidomide-treated group showed a significant increase of urinary protein on day 3. ED-1-positive cells stagnated longer and the matrix increase was delayed. STI571 caused suppression of mesangial proliferation, and microaneurysm remained longer than in the other 2 groups, which resulted in delay of glomerular capillary reconstruction. The number of alfa-SMA-positive cells appeared to be smaller in both the thalidomide- and the STI571-treated groups. CONCLUSIONS: Thalidomide had an effect in the early period of the experiment; however, there was no influence on the repair of glomerular capillary at the end. STI571 treatment, which inhibited proliferation of alfa-SMA-positive cells, seems to show that some degree of mesangial cell proliferation is necessary to reconstruct capillary structures and to regain glomerular function.

Renal involvement in bone marrow transplantation.

Bone marrow transplantation (BMT) is an effective therapeutic strategy for leukaemic malignancies and depressed bone marrow following cancer. However, its side effects on kidneys have been reported. Some drugs and irradiation are also suggested to be nephrotoxic. It is well known that haemolytic uraemic syndrome (HUS) after BMT develops as late-onset BMT nephropathy. Cyclosporine A (CsA) is a possible cause. Radiation nephropathy shows changes that are similar to the histology of HUS. These findings suggest that endothelial damage is closely associated with the pathogenesis of post-BMT nephropathy. Recently, some patients have developed glomerulonephritis accompanied by graft-versus-host disease (GVHD) after BMT. In these patients immune deposits are found mainly in subepithelium and mesangium equal to those of secondary membranous glomerulonephritis. A murine experimental model of GVHD manifests similar symptoms and histological changes to those of actual patients and may suggest the pathogenesis of glomerulonephritis.

Decreased distribution of nitric oxide synthase and vasoactive intestinal polypeptide positive nerve cells in the sphincter of Oddi in humans with pancreatobiliary diseases.

To better understand the relationship between innervation in the sphincter of Oddi and pancreatobiliary diseases, nerve cells which possess nitric oxide synthase (NOS) and/or vasoactive intestinal polypeptide (VIP) were studied immunohistochemically in the sphincter of Oddi and duodenum of humans. Specimens from autopsies included 11 cases with pancreatobiliary diseases and 7 cases without such diseases. An elaborate nerve network was revealed with an anti-S-100 antibody in the sphincter of Oddi and duodenum of all specimens. In the sphincter of Oddi of the control group, approximately 47% of the myenteric nerve cells were NOS positive, whereas 54% were VIP positive. Of the NOS positive nerve cells, 21% were also VIP positive. In contrast, 11% of the nerve cells in the sphincter of Oddi of the disease group were NOS positive while 32% were VIP positive. Within the duodenal myenteric plexus of the control group, 35% of all nerve cells were NOS positive while 40% was VIP positive; among them, 23% of the NOS positive cells were VIP positive. Similar results were observed in the duodenum of the disease group. These data indicate that abundant NOS and VIP positive innervation is present in the sphincter of Oddi and duodenum in humans. The lower proportion of NOS positive or VIP positive nerve cells of the disease group may suggest an inadequacy of the sphincter of Oddi to relax.

Immunohistochemical detection of immunoglobulins and complements in formaldehyde-fixed and paraffin-embedded renal biopsy tissues; an adjunct for diagnosis of glomerulonephritis.

BACKGROUND: The present study was undertaken to demonstrate the deposition of immunoglobulins or complements in formaldehyde-fixed and paraffin-embedded renal biopsy tissues through the unmasking of antigens with microwave treatment plus protease digestion or trypsin digestion. METHODS: Biopsy samples from patients with IgA nephritis (n = 7), lupus nephritis (7), membranous nephropathy (7) and mesangiocapillary glomerulonephritis (3) were used. Antigen unmasking was performed with (i) microwave treatment plus protease digestion for 10, 30 or 60 min, or (ii) digestion with 0.25% trypsin for 60 or 120 min. RESULTS: Microwave treatment plus protease digestion for 30 or 60 min and trypsin digestion for 120 min provided good results for the unmasking of immunoglobulins in glomeruli with structural preservation. The IgA deposits in IgA nephritis and IgG deposits in lupus nephritis and membranous nephropathy were clearly revealed in more than 80% of cases by both pretreatments. Microwave treatment plus protease digestion for 30 min revealed the deposition of C3 in all cases of mesangiocapillary glomerulonephritis and lupus nephritis and was superior to trypsin digestion. Characteristic patterns of C3 deposition were observed for these forms of glomerulonephritis, although C3 deposits in membranous nephropathy were detected in only 50% of cases. It was not possible to unmask all of the antigens in the glomeruli, especially those with weak immunofluorescence. CONCLUSION: Microwave treatment plus protease digestion is effective for the unmasking of antigens in paraffin sections and as useful for the diagnosis of immune-mediated glomerulonephritis as trypsin digestion.

Renal cholesterol embolism: analysis of two spontaneous autopsy cases.

Two cases of spontaneous cholesterol embolism, which followed different clinical courses, acute and chronic renal failure, are presented and histopathological lesions are compared. Both cases were diagnosed as cholesterol embolism post-mortem. Case 1 (a 66-year-old man) had acute onset of illness with fever, leucocytosis and renal failure, diagnosed as vasculitis, and died of rupture of an abdominal aortic aneurysm. Case 2 (an 84-year-old man) had eosinophilia of unknown aetiology for 7 years with intermittent worsening of renal function and died of sepsis. Case 1 had diffuse cholesterol crystal emboli in the interlobular arteries and arterioles of the kidney, but case 2 had patchy cholesterol emboli in the interlobular arteries of the kidney. The aorta of case 1 was diffusely ulcerated, which is in contrast to that of case 2, who had limited ulceration in thoracic aorta, which might have contributed to the long duration of illness. Immunohistochemically, the number of macrophages and T cells that infiltrated around cholesterol emboli in the arteries was more in case 1 (macrophages 27.7, T cells 36.1/mm(2)) than in case 2 (2.7, 1.38/mm(2)). Focal interstitial inflammation occurred in both cases. In case 1, marked tubulitis was observed. Case 2 had rather severe atrophy of the tubules and fibrotic interstitium where mast cells were rich (31.9/mm(2)). The number of B cells and eosinophils was few in case 2 (11.35, 0.7/mm(2)) compared with case 1 (101.9, 16.15/mm(2)). These results suggest that in acute lesions of renal cholesterol embolism, macrophages and T cells accumulate around cholesterol crystals and cause tubulointerstitial inflammatory lesions with other inflammatory cells. In chronic lesions, macrophages, T cells and mast cells are the major inflammatory cells present in the interstitium.