Chronic VEGF blockade worsens glomerular injury in the remnant kidney model

VEGF inhibition can promote renal vascular and parenchymal injury, causing proteinuria, hypertension and thrombotic microangiopathy. The mechanisms underlying these side effects are unclear. We investigated the renal effects of the administration, during 45 days, of sunitinib (Su), a VEGF receptor inhibitor, to rats with 5/6 renal ablation (Nx). Adult male Munich-Wistar rats were distributed among groups S+V, sham-operated rats receiving vehicle only; S+Su, S rats given Su, 4 mg/kg/day; Nx+V, Nx rats receiving V; and Nx+Su, Nx rats receiving Su. Su caused no change in Group S. Seven and 45 days after renal ablation, renal cortical interstitium was expanded, in association with rarefaction of peritubular capillaries. Su did not worsen hypertension, proteinuria or interstitial expansion, nor did it affect capillary rarefaction, suggesting little angiogenic activity in this model. Nx animals exhibited glomerulosclerosis (GS), which was aggravated by Su. This effect could not be explained by podocyte damage, nor could it be ascribed to tuft hypertrophy or hyperplasia. GS may have derived from organization of capillary microthrombi, frequently observed in Group Nx+Su. Treatment with Su did not reduce the fractional glomerular endothelial area, suggesting functional rather than structural cell injury. Chronic VEGF inhibition has little effect on normal rats, but can affect glomerular endothelium when renal damage is already present.

Invariant natural killer T cell agonist modulates experimental focal and segmental glomerulosclerosis

A growing body of evidence demonstrates a correlation between Th2 cytokines and the development of focal and segmental glomerulosclerosis (FSGS). Therefore, we hypothesized that GSL-1, a monoglycosylceramide from Sphingomonas ssp. with pro-Th1 activity on invariant Natural Killer T (iNKT) lymphocytes, could counterbalance the Th2 profile and modulate glomerulosclerosis. Using an adriamycin(ADM)-based model of FSGS, we found that BALB/c mice presented albuminuria and glomerular degeneration in association with a Th2-like pro-fibrogenic profile; these mice also expressed a combination of inflammatory cytokines, such as IL-4, IL-1α, IL-1β, IL-17, TNF-α, and chemokines, such as RANTES and eotaxin. In addition, we observed a decrease in the mRNA levels of GD3 synthase, the enzyme responsible for GD3 metabolism, a glycolipid associated with podocyte physiology. GSL-1 treatment inhibited ADM-induced renal dysfunction and preserved kidney architecture, a phenomenon associated with the induction of a Th1-like response, increased levels of GD3 synthase transcripts and inhibition of pro-fibrotic transcripts and inflammatory cytokines. TGF-β analysis revealed increased levels of circulating protein and tissue transcripts in both ADM- and GSL-1-treated mice, suggesting that TGF-β could be associated with both FSGS pathology and iNKT-mediated immunosuppression; therefore, we analyzed the kidney expression of phosphorylated SMAD2/3 and SMAD7 proteins, molecules associated with the deleterious and protective effects of TGF-β, respectively. We found high levels of phosphoSMAD2/3 in ADM mice in contrast to the GSL-1 treated group in which SMAD7 expression increased. These data suggest that GSL-1 treatment modulates the downstream signaling of TGF-β through a renoprotective pathway. Finally, GSL-1 treatment at day 4, a period when proteinuria was already established, was still able to improve renal function, preserve renal structure and inhibit fibrogenic transcripts. In conclusion, our work demonstrates that the iNKT agonist GSL-1 modulates the pathogenesis of ADM-induced glomerulosclerosis and may provide an alternative approach to disease management.

A review of the diagnosis and treatment of Ochratoxin A inhalational exposure associated with human illness and kidney disease including focal segmental glomerulosclerosis

Ochratoxin A (OTA) exposure via ingestion and inhalation has been described in the literature to cause kidney disease in both animals and humans. This paper reviews Ochratoxin A and its relationship to human health and kidney disease with a focus on a possible association with focal segmental glomerulosclerosis (FSGS) in humans. Prevention and treatment strategies for OTA-induced illness are also discussed, including cholestyramine, a bile-acid-binding resin used as a sequestrant to reduce the enterohepatic recirculation of OTA.

Detection of intrarenal microstructural changes with supersonic shear wave elastography in rats

OBJECTIVES

To evaluate, in a rat model of glomerulosclerosis, whether ultrasonic shear wave elastography detects kidney cortex stiffness changes and predicts histopathological development of fibrosis.

MATERIALS AND METHODS

Three groups were studied transversally: a control group (n = 8), a group after 4 weeks of L-NAME administration (H4, n = 8), and a group after 6 weeks (H6, n = 15). A fourth group was studied longitudinally (n = 8) before, after 4 weeks and after 7 weeks of L-NAME administration. Shear modulus of renal cortex was quantified using supersonic shear imaging technique. Urine was analysed for dosage of protein/creatinine ratio. Kidneys were removed for histological quantification of fibrosis.

RESULTS

Diseased rats showed an increased urinary protein/creatinine ratio. Cortical stiffness expressed as median (interquartile range) was 4.0 kPa (3.3-4.5) in control kidneys. It increased in all but one pathological groups: H4: 7.7 kPa (5.5-8.6) (p < 0.01); H6: 4.8 kPa (3.9-5.9) (not significant); in the longitudinal cohort, from 4.5 kPa (3.1-5.9) to 7.7 kPa (5.9-8.3) at week 4 (p < 0.05) and to 6.9 kPa (6.1-7.8) at week 7 (p < 0.05). Stiffness values were correlated with the proteinuria/creatininuria ratio (r = 0.639, p < 0.001).

CONCLUSIONS

Increased cortical stiffness is correlated with the degree of renal dysfunction. More experience in other models is necessary to understand its relationship with microstructural changes.

Treatment with IFN-{alpha}, -{beta}, or -{gamma} is associated with collapsing focal segmental glomerulosclerosis

BACKGROUND AND OBJECTIVES

Treatment with IFN is rarely associated with nephrotic syndrome and renal biopsy findings of minimal-change disease or FSGS.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We report 11 cases of collapsing FSGS that developed during treatment with IFN and improved after discontinuation of therapy.

RESULTS

The cohort consists of seven women and four men with a mean age of 48.2 yr. Ten of the 11 patients were black. Six patients were receiving IFN-alpha for hepatitis C virus infection (n = 5) or malignant melanoma (n = 1), three were receiving IFN-beta for multiple sclerosis, and two were treated with IFN-gamma for idiopathic pulmonary fibrosis. After a median and mean [corrected] duration of therapy of 4.0 and 12.6 months, respectively, patients presented with acute renal failure (mean creatinine 3.5 mg/dl) and nephrotic-range proteinuria (mean 24-hour urine protein 9.7 g). Renal biopsy revealed collapsing FSGS with extensive foot process effacement and many endothelial tubuloreticular inclusions. Follow-up was available for 10 patients, all of whom discontinued IFN. At a mean of 23.6 months, nine of 10 patients had improvement in renal function, including one with complete remission and two with partial remission. Among the seven patients with available data, mean proteinuria declined from 9.9 to 3.0 g/d. Four of the seven patients were treated with immunosuppression, and there was no detectable benefit.

CONCLUSIONS

Collapsing FSGS may occur after treatment with IFN-alpha, -beta, or -gamma and is typically accompanied by the ultrastructural finding of endothelial tubuloreticular inclusions. Optimal therapy includes discontinuation of IFN.

Development of focal segmental glomerulosclerosis after anabolic steroid abuse

Anabolic steroid abuse adversely affects the endocrine system, blood lipids, and the liver, but renal injury has not been described. We identified an association of focal segmental glomerulosclerosis (FSGS) and proteinuria in a cohort of 10 bodybuilders (six white and four Hispanic; mean body mass index 34.7) after long-term abuse of anabolic steroids. The clinical presentation included proteinuria (mean 10.1 g/d; range 1.3 to 26.3 g/d) and renal insufficiency (mean serum creatinine 3.0 mg/dl; range 1.3 to 7.8 mg/dl); three (30%) patients presented with nephrotic syndrome. Renal biopsy revealed FSGS in nine patients, four of whom also had glomerulomegaly, and glomerulomegaly alone in one patient. Three biopsies revealed collapsing lesions of FSGS, four had perihilar lesions, and seven showed > or =40% tubular atrophy and interstitial fibrosis. Among eight patients with mean follow-up of 2.2 yr, one progressed to ESRD, the other seven received renin-angiotensin system blockade, and one also received corticosteroids. All seven patients discontinued anabolic steroids, leading to weight loss, stabilization or improvement in serum creatinine, and a reduction in proteinuria. One patient resumed anabolic steroid abuse and suffered relapse of proteinuria and renal insufficiency. We hypothesize that secondary FSGS results from a combination of postadaptive glomerular changes driven by increased lean body mass and potential direct nephrotoxic effects of anabolic steroids. Because of the expected rise in serum creatinine as a result of increased muscle mass in bodybuilders, this complication is likely underrecognized.

Increased Oxidative Stress in the Mouse Adriamycin Model of Glomerulosclerosis Is Accompanied by Deposition of Ferric Iron and Altered GGT Activity in Renal Cortex

Chronic renal failure evolves inevitable towards glomerular and tubulo-interstitial sclerosis. This pathological process involves a disturbed redox status of the kidney tissue, leading to irreversible damage. In this study we investigate in an adriamycin model of chronic renal failure in mice the evolution of in vivo hydrogen peroxide production, and the possible role of gamma-glutamyl transpeptidase and ferric iron in the process. Histological changes and ferric iron deposits are evaluated by histochemical staining. To evaluate oxidative stress residual catalase activity, TBARS formation and gamma-glutamyl transpeptidase activity are measured spectrophotometrically. While catalase activity remains the same, a decreased residual catalase activity indicates an increased formation of hydrogen peroxide. Both the activity of gamma-glutamyl transpeptidase and TBARS formation is increased at early stages of the disease. Ferric iron is clearly present in the proximal tubule. Twenty days after adriamycin injection all parameters decrease, probably due to the destruction of the tissue. Our data show the involvement of oxidative stress in the progression of adriamycin induced renal failure in mice. Both radical production and oxidative damage are measurable, while the altered activity of gamma-glutamyl transpeptidase and the deposition of ferric iron suggest the involvement of these factors in the development of a disturbed redox status in the kidney cortex.

Rapamycin attenuates the severity of murine adriamycin nephropathy

BACKGROUND

Rapamycin is an immunosuppressive drug with potent antifibrotic activity. We evaluated the effect of rapamycin on murine adriamycin nephropathy, a model of progressive glomerulosclerosis and tubulointerstitial fibrosis.

METHODS

Adriamycin nephropathy was induced in Balb/c mice by a single intravenous injection of adriamycin. The mice were treated orally with either saline or rapamycin, beginning at the time of adriamycin injection or rapamycin starting 1 week after adriamycin injection. The mice were sacrificed 6 weeks after adriamycin injection.

RESULTS

Saline-treated mice developed massive proteinuria and impaired renal function. Kidney sections from saline-treated mice showed marked focal segmental glomerulosclerosis, tubular dilation with protein cast deposition, interstitial fibrosis, and numerous infiltrating macrophages and T lymphocytes. The intrarenal expression of Collagen I and RANTES was also increased. In contrast, both groups of rapamycin-treated mice had markedly reduced proteinuria and preserved renal function, with only mild histological abnormalities. The intrarenal expression of Collagen I and RANTES was reduced, concomitant with a significant reduction in interstitial inflammatory cell infiltration.

CONCLUSIONS

Rapamycin is effective in attenuating the glomerular and tubulointerstitial abnormalities in adriamycin nephropathy. The beneficial effects of rapamycin are mediated, at least in part, through reduced RANTES expression and inflammatory cell infiltration.

Osteopontin as an injury marker expressing in epithelial hyperplasia lesions helpful in prognosis of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is characterized by typical sclerosis but also shows other non-sclerotic lesions that provide prognostic informations. The glomerular epithelial hyperplasia lesion (EPHL) that develops earlier than the sclerotic lesions is a key determinant of progression of FSGS. However, the relationship among EPHL, glomeular sclerosis, and macrophage infiltration in FSGS is unclear, and the EPHL-associated markers helpful for prognosis of FSGS have still not been completely identified. Here, we performed clinicopathologic, immunochemical, and molecular analyses to examine whether osteopontin (OPN), a macrophage chemokine, is an injury marker of EPHLs correlating with glomerular sclerosis and macrophage mobilization. First, the FSGS model was induced in Balb/c mice by a single injection of adriamycin, and consecutive sclerosis changes were evaluated. In parallel, we used reverse transcription-polymerase chain reaction and Western blot analyses to determine levels of OPN in isolated glomeruli and urine, respectively. Immunohistochemistry was applied to assess the OPN expression in EPHLs and macrophage infiltration around the glomeruli. Our results showed that, within glomeruli, OPN expressed restrictedly within EPHL; the OPN mRNA and protein of glomeruli increased on day 11, correlating well with the early EPHL, and following sclerosis and macrophage infiltration. In addition, immunohistochemistry (IHC) staining of OPN greatly highlighted early glomerular EPHLs, helping microscopic identification of EPHLs. We propose that the OPN expression in EPHLs could contribute to the progression of FSGS by recruiting macrophage toward the compromised glomeruli. Detection of OPN in glomeruli and urine could be helpful in prognosis of FSGS.

Collapsing focal segmental glomerulosclerosis in a liver transplant recipient on alendronate

We describe a case of collapsing focal segmental glomerulosclerosis and severe kidney dysfunction in a liver transplant recipient after the initiation of alendronate for osteopenia. In view of the increasing incidence of chronic kidney disease in long-term liver transplant patients, bisphosphonates need to be used with caution in these patients. The usefulness of bisphosphonates for the prevention of early bone loss after liver transplantation is increasingly reported. However, there is little information on the safety and efficacy of these drugs when used in the later stages of liver transplant, particularly in the presence of chronic kidney disease. Bisphosphonates are excreted unchanged via the kidneys after reaching the systemic circulation. Some cases of severe kidney injury, in particular collapsing focal segmental glomerulosclerosis, have been described that are associated with the use of pamidronate. Alendronate, a widely used bisphosphonate in transplant patients, has not been related to kidney toxicity. We describe a case of collapsing focal segmental glomerulosclerosis and severe kidney dysfunction in a liver transplant recipient soon after the initiation of alendronate for osteopenia. Possible pathogenetic mechanisms are discussed. In view of the increasing incidence of chronic kidney disease in long-term liver transplant patients, bisphosphonate need to be used with caution in patients with a low glomerular filtration rate.

[Effects of Haikun Shenxi on expression of platelet-derived growth factor-B and mRNA in renal tissue of rats with adriamycin nephropathy]

OBJECTIVE

To investigate the effects of Haikun Shenxi on the expression of platelet-derived growth factor-BB (PDGF-BB) and mRNA in renal tissue of rats with adriamycin nephropathy.

METHOD

Rat model was established by unilateral nephrectomy and injecting adriamycin intraperitoneally. The adriamycin-induced nephrotic rats were randomly divided into 6 groups: normal group, sham operation group, model group, lotensin treatment group, Haikun Shenxi low and high dose treatment groups (0.77, 0.08 mg x kg(-1). Ten weeks later, the 24 hour urine protein and blood biochemistry examinations and renal pathologic changes were observed, and the expression of PDGF-BB and mRNA was measured using immunohistochemical method.

RESULT

Compared with model group, proteinuria and the levels of serum creatinine (Scr) , urea nitrogen (BUN) were decreased obviously in both Haikun Shenxi low and high dose groups. The expression of PDGF-BB and mRNA was mostly presented in cytoplasm of renal tubular epithelial cells and mesangial area, and it could be reduced significantly after treatment (P < 0. 05).

CONCLUSION

The level of PDGF-BB and mRNA is high in renal tissue of adriamycin-induced nephrotic rats. This progress could be effectively inhibited by Haikun Shenxi and the mechanism may be that it can control the excessive expression of PDGF-BB and mRNA.

The renal clearance of dextran sulfate decreases in puromycin aminonucleoside-induced glomerulosclerosis: A puzzle observation

BACKGROUND

Puromycin aminonucleoside-induced nephrosis is characterized by increased renal excretion of plasma proteins. We employed this experimental model to study the urinary clearance of dextran sulfate.

METHODS

The dextran sulfate eliminated by the urine was determined using a metachromatic assay. Polysaccharide fragments were analyzed by chromatographic and electrophoretic procedures. Disaccharide composition of the glomerular heparan sulfate was assessed using digestion with specific lyases.

RESULTS

In normal rats dextran sulfate is partially degraded to lower molecular weight fragments and only then eliminated by the urine. Surprisingly, in puromycin aminonucleoside-induced glomerulosclerosis the molecular size of the fragments of dextran sulfate found in the urine is the same or even lower than in control animals in spite of the marked proteinuria. Furthermore, urinary excretion of dextran sulfate decreases in the experimentally induced nephrosis. This observation cannot be totally attributed to a reduced number of physiologically active nephrons since the glomerular filtration rate decreases approximately 32% after puromycin aminonucleoside administration while the urinary excretion of 8 kDa-dextran sulfate decreases 3-fold. The glomerular heparan sulfate shows reduced sulfation when compared with normal animals. Possibly puromycin aminonucleoside decreases the activity of kidney endoglycosidases, which reduce the molecular size of the sulfated polysaccharide, leading to a decrease in its renal clearance. Reduced sulfation of the glomerular heparan sulfate in the puromycin aminonucleoside-induced nephrosis does not alter the size of the dextran sulfate eliminated by the kidney, as suggested for protein.

CONCLUSIONS

Each pathological process induces a particular modification in the kidney, which in turn can affect the renal selectivity to specific macromolecules in different ways.

Ex vivo programmed macrophages ameliorate experimental chronic inflammatory renal disease

Macrophage infiltration of the kidney is a prominent feature associated with the severity of renal injury and progressive renal failure. To determine the influence of macrophages in renal disease models in the absence of endogenous T and B cells, we performed adoptive transfer of macrophages into severe combined immunodeficient (SCID) mice. In this study, macrophages were isolated from the spleens of BALB/c mice and stimulated with lipopolysaccharide to induce classically activated M1 macrophages or with interleukin-4 (IL-4) and IL-13 to induce alternatively activated M2 macrophages. These macrophages were then infused into SCID mice with adriamycin nephropathy; an in vivo model of chronic inflammatory renal disease analogous to human focal segmental glomerulosclerosis. Mice infused with M1 macrophages had a more severe histological and functional injury, whereas M2 macrophage-induced transfused mice had reduced histological and functional injury. Both M1 and M2 macrophages localized preferentially to the area of injury and maintained their phenotypes even after 4 weeks. The protective effect of M2 macrophages was associated with reduced accumulation and possibly downregulated chemokine and inflammatory cytokine expression of the host infiltrating macrophages. Our findings demonstrate that macrophages not only act as effectors of immune injury but can be induced to provide protection against immune injury.

High sirolimus levels may induce focal segmental glomerulosclerosis de novo

Sirolimus has been associated with high-range proteinuria when used in replacement of calcineurin inhibitors in renal transplant recipients with chronic allograft nephropathy (CAN). Primary FSGS was demonstrated previously in some such patients, but the coexistence of CAN lesions made the interpretation uneasy. However, nephrotic syndrome and FSGS were observed recently in three patients who received sirolimus de novo, without medical history of primary FSGS or CAN. Markers of podocyte differentiation were studied in kidney biopsies of the three patients who received sirolimus de novo and of five patients who switched to sirolimus. All patients developed FSGS lesions of classic type (not otherwise specified), but only switched patients exhibited advanced sclerotic lesions. Immunohistochemistry showed that some podocytes in FSGS lesions had absent or diminished expression of the podocyte-specific epitopes synaptopodin and p57, reflecting dedifferentiation, and had acquired expression of cytokeratin and PAX2, reflecting a immature fetal phenotype. Such a pattern of epitope expression provides evidence for podocyte dysregulation. Moreover, a decrease in vascular endothelial growth factor expression was observed in some glomeruli. In conclusion, sirolimus induces FSGS that is responsible for proteinuria in some transplant patients.

Dietary protein induces endothelin-mediated kidney injury through enhanced intrinsic acid production

Dietary protein as casein (CAS) augments intrinsic acid production, induces endothelin-mediated kidney acidification, and promotes kidney injury. We tested the hypothesis that dietary CAS induces endothelin-mediated kidney injury through augmented intrinsic acid production. Munich-Wistar rats ate minimum electrolyte diets from age 8 to 96 weeks with 50 or 20% protein as either acid-inducing CAS or non-acid-inducing SOY. Urine net acid excretion and distal nephron net HCO3 reabsorption by in vivo microperfusion (Net J(HCO3)) were higher in 50 than 20% CAS but not 50 and 20% SOY. At 96 weeks, 50% compared the 20% CAS had higher urine endothelin-1 excretion (U(ET-1)V) and a higher index of tubulo-interstitial injury (TII) at pathology (2.25+/-0.21 vs 1.25+/-0.13 U, P<0.03), but each parameter was similar in 50 and 20% SOY. CAS (50%) eating NaHCO3 to reduce intrinsic acid production had lower Net J(HCO3), lower U(ET-1)V, and less TII. By contrast, 50% SOY eating dietary acid as (NH4)2SO4 had higher Net J(HCO3), higher U(ET-1)V, and more TII. Endothelin A/B but not A receptor antagonism reduced Net J(HCO3) in 50% CAS and 50% SOY+(NH4)2SO4 animals. By contrast, endothelin A but not A/B receptor antagonism reduced TII in each group. The data support that increased intake of acid-inducing dietary protein induces endothelin B-receptor-mediated increased Net J(HCO3) and endothelin A-receptor-mediated TII through augmented intrinsic acid production.

Life-threatening thrombocytopenia and nephrotic syndrome due to focal segmental glomerulosclerosis associated with pegylated interferon alpha-2b and ribavirin treatment for hepatitis C

BACKGROUND

Interferon-alpha (IFN-alpha)and ribavirin combination therapy for chronic infection with hepatitis C virus produces a number of well-described side effects. Combination therapy with pegylated interferon (PEG-IFN) yields an adverse event profile similar to that observed with the standard IFN, although the frequency of certain adverse events may vary according to the preparation.

CASE REPORT

We report the case of a 44-year-old man who was treated with ribavirin and PEG-IFN-alpha-2b for chronic hepatitis C and developed two rare side effects simultaneously on the 16th week of therapy: severe thrombocytopenia and nephrotic syndrome due to focal segmental glomerulosclerosis. The antiviral treatment was immediately interrupted and the patient received immunosuppressive therapy. He promptly recovered from the thrombocytopenia and partially and slowly from the nephrotic syndrome. To our knowledge, this is the first case reported of the development of such complications at the same time.

Turbulence of glomerular hemodynamics involved in progressive glomerulosclerosis

There is increasing evidence that changes of glomerular hemodynamics or glomerular growth responses may promote the development of glomerulosclerosis. Major problems retarding research progress include lack of suitable experimental animal models, with the exception of the ablation model, and the need for in vivo real-time analysis of glomerular hemodynamics. This study examined the sequence of pathological changes from the viewpoints of microcirculation and histopathology, from the acute stage to the chronic course and the final stage of glomerulosclerosis, using the confocal laser scanning microscope system. There is a marked difference in prognosis between sham-operated (two-kidney) and nephrectomized (one-kidney) rats after injection with anti-Thy-1 antibody. The former reversibly returns to normal and the latter irreversibly go to progressive sclerosis, respectively. The turning point determining the progression of glomerulosclerosis in both groups seemed to be the period from 7 to 14 days after disease induction, when disturbance of local intraglomerular blood flow continued in the one-kidney groups. In conclusion, this study provides the first hemodynamic-based evidence showing that disturbance of intraglomerular microcirculation is a critical marker for progressive glomerulosclerosis.

A potential pathological role of angiopoietins expression in glomeruli during progressive glomerulisclerosis related to podocyte injury

A potential pathological role of angiopoietins (Ang) in glomeruli following podocyte injury-induced progressive glomerulosclerosis was explored. Eighty male Wistar rats were randomly allocated into sham operation group (Sham, n = 25), Uninephrectomy group (UPHT, n = 25) and Uninephrectomy+Daunorubicin group (DRB, n = 30). In DRB group, daunorubicin (5 mg/kg) was injected via tail vein on the 7th and 14th day after uninephrectomy. At week 1, 2, 4, 6 and 8 respectively following establishment of the animal model, 5 rats in Sham group and UPHT group, and 6 in DRB group were taken respectively for determining 24-h urinary protein excretion rate (24hUPER), blood urea nitrogen (BUN) and serum creatinine (Scr). The sections of kidneys were examined by an electric microscope, PAS staining, immunohistochemical staining and in situ hybridization histochemistry. The results showed that 24hUPER, BUN and Scr in DRB group were more than those in Sham group and UPHT group at the same time points, and there was a trend towards an increase on level of GSI in DRB group from week 2 to week 8. Electric microscopy revealed that podocyte injury presented in DRB group. The expression of Ang1 mRNA and protein in glomeruli of DRB group was decreased, while the expression of Ang2 protein in glomeruli of DRB group increased. Meanwhile, the expression of Ang1 mRNA had a negative correlation with the expression of Ang2 mRNA, and the expression of Ang1 protein had a positive correlation with the expression of Ang1 mRNA, and had a negative correlation with 24hUPER, BUN, Scr, glomerular sclerotic index (GSI), the expression of Ang2 protein and CoIV protein. The expression of Ang2 protein had a positive correlation with the expression of Ang2 mRNA, and had a positive correlation with 24hUPER, BUN, Scr, GSI, the expression of CoIV protein. It was concluded that podocyte injury might lead to an alteration in the expression of Ang1 and Ang2 within glomeruli. Ang2 may get rid of inhibition from Ang1 for downregulation of the Ang1 expression, which facilitate upregulation of the Ang2 expression in glomeruli to promote progressive glomerulosclerosis in the rats.

A protective role for programmed death 1 in progression of murine adriamycin nephropathy

Programmed death 1 (PD-1) is a novel member of the CD28/cytotoxic T-lymphocyte-associated protein-4 superfamily, which plays an important role in the regulation of activated T cells. However, it is not clear how PD-1 is expressed in normal and diseased kidney, nor if it has a role in progression of chronic renal disease. PD-1 expression and the effect of monoclonal anti-PD-1 antibody (Ab) were examined in murine adriamycin nephropathy (AN). BALB/c mice were divided into three groups: (a) normal mice, (b) adriamycin (ADR) with control immunoglobulin (Ig)G (ADR-IgG), and (c) ADR with anti-PD-1 Ab (ADR-Ab). AN was induced by a single intravenous injection of ADR. Anti-PD-1 Ab was given by intraperitoneal injection on alternate days from day 0 to day 10, or to day 18. Animals were killed at week 4. Renal function, histological change, and cytokine expression were examined. PD-1 mRNA was detected in kidney tissue of mice with AN in a dose- and time-dependent manner. PD-1 was mainly expressed on injured tubule cells and some interstitial cells, which co-stained with alpha-smooth muscle actin in AN, but not in normal kidney. Anti-PD-1 treatment up to day 18, but not to day 10, worsened glomerular and tubulointerstitial injury. The ratio of urinary protein/creatinine was significantly higher in ADR-Ab mice than ADR-IgG mice. The number of macrophages was significantly increased in ADR-Ab mice compared with ADR-IgG mice. Blockade of PD-1 worsened progressive renal histopathological and functional injury in murine AN. This suggests a possible protective role for PD-1 in chronic renal disease, and its potential as a treatment to slow disease progression.

Proliferating cells in HIV and pamidronate-associated collapsing focal segmental glomerulosclerosis are parietal epithelial cells

Collapsing focal segmental glomerulosclerosis (cFSGS) is characterized by hyperplasia of glomerular epithelial cells. In a mouse model of FSGS and in a patient with recurrent idiopathic FSGS, we identified the proliferating cells as parietal epithelial cells (PECs). In the present study, we have evaluated the origin of the proliferating cells in cFSGS associated with human immunodeficiency virus (HIV) and pamidronate. We performed a detailed study of glomerular lesions in biopsies of two patients with HIV-associated cFSGS and a nephrectomy specimen of a patient with pamidronate-associated cFSGS. Glomeruli were studied by serial sectioning using light and electron microscopy and immunohistochemistry to determine the epithelial cell phenotype. We used Synaptopodin, vascular endothelial growth factor, and CD10 as podocyte markers, CK8 and PAX2 as PEC markers and Ki-67 as marker of cell proliferation. The newly deposited extracellular matrix was characterized using antiheparan sulfate single-chain antibodies. The proliferating cells were negative for the podocyte markers, but stained positive for the PEC markers and the cell proliferation marker Ki-67. The proliferating PAX-2 and CK8 positive cells that covered the capillary tuft were always in continuity with PAX-2/CK8 positive cells lining Bowman's capsule. The matrix deposited by these proliferating cells stained identically to Bowman's capsule. Our study demonstrates that PECs proliferate in HIV and pamidronate-associated cFSGS. Our data do not support the concept of the proliferating, dedifferentiated podocyte.

Reduced podocyte expression of alpha3beta1 integrins and podocyte depletion in patients with primary focal segmental glomerulosclerosis and chronic PAN-treated rats

Integrins attach cells to extracellular matrix (ECM) and mediate signals from ECM to cells or from cells to ECM. They regulate cell functions, including adhesion, migration, cell cycle regulation, and differentiation. Podocytes may detach from the glomerular basement membrane (GBM) and be excreted in the urine, and proteinuria is found in patients with primary focal segmental glomerulosclerosis (FSGS); both may be associated with loss of alpha3beta1integrins. In this study, we have examined the podocyte number in patients with primary FSGS and normal controls, and the alpha3- and beta1-integrin subunits expression of podocytes in patients with primary FSGS and chronic puromycin aminonucleoside (PAN)-treated rats by the morphometric, immunoperoxidase histochemical, and immunoelectron microscopic examination. We also measured their expression serially in rats that received repeated PAN injection. The results showed that the podocyte number was significantly decreased in patients with primary FSGS than in normal control (P < 0.05). The immunostaining score showed that both alpha3- and beta1-integrin subunits on podocytes in patients with primary FSGS were significantly lower than in normal controls (both P < 0.01). The number of immuno-gold particles of alpha3- and beta1-integrins at the effaced foot process area of patients with primary FSGS were also significantly decreased than that of normal controls (both P < 0.05). The immunostaining score of both alpha3- and beta1-integrin subunits was negatively correlated with the degree of glomerular sclerosing score and the amount of daily protein loss, and they were positively correlated with the number of podocytes. Chronic 12-week PAN-treated rats showed similar findings with decreased immunostaining expression and immuno-gold particles of alpha3-integrin on podocytes than in normal control (both P < 0.05). The chronic PAN-treated rats also showed a trend toward gradually decreased immunostaining expression of alpha3-integrin subunit on podocyte during the progress from normal to FSGS state. These studies indicate that podocyte expression of alpha3- and beta1-integrin subunits is significantly reduced in humans with primary FSGS and chronic PAN-treated rats, before the morphological changes of FSGS are observed. The decreased podocyte expression of alpha3beta1 integrins is closely related with podocyte depletion, glomerular sclerosis, and daily protein loss in patients with primary FSGS.