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Background: There is a lack of new therapeutic strategies for IgA nephropathy. Low-dose sirolimus inhibits mesangial cell proliferation and renal fibrosis in animal models., Methods: We performed a pilot, randomized controlled trial to evaluate the efficacy and safety of low-dose sirolimus in patients with a high-risk IgA nephropathy. Twenty-three patients with a glomerular filtration rate (GFR) within 30-60 mL/min and/or proteinuria >1 g/day were randomly assigned to low-dose sirolimus plus enalapril and atorvastatin (SRL group, n = 14) or enalapril plus atorvastatin (CONTROL group, n = 9). Primary composite end point was variation of haematuria, proteinuria and blood pressure. Secondary end points were isotopic GFR, renal histology evaluated by Oxford classification and safety parameters evaluated at 6 and 12 months., Results: Primary end point improved significantly in the SRL group at 12 months. Regarding isotopic GFR, patients included in the CONTROL group lost 8 mL/min/1.73 m(2), whereas those in the SRL arm improved 5 mL/min/1.73 m(2) (P = 0.03). Proteinuria decreased similarly in both study groups. At 1 year, SRL treatment was associated with a significant reduction of mesangial and endocapillary proliferation, whereas glomerular sclerosis, tubular atrophy and interstitial fibrosis were similar. Sirolimus was well tolerated; all patients remained on therapy at 12 months., Conclusion: The addition of low-dose sirolimus to enalapril and statin is safe, stabilizes renal function and reduces glomerular proliferative lesions in patients with poor prognosis IgA nephropathy.

After transplantation, glomerular volumes increases and large glomerular volume at 4 months is associated with better renal function. The aim is to characterize glomerular adaptation after the fourth month in two serial protocol biopsies and its relationship with subclinical rejection and chronic allograft nephropathy (CAN). Mean glomerular volume (Vg) was estimated according to the Weibel and Gomez method in a 4-month and 1-year serial protocol biopsies in 61 stable grafts. Glomerular enlargement (deltaVg) was calculated as the Vg difference between both biopsies. Banff schema was used to evaluate renal biopsies. Vg increased from 4.4+/-2.4 to 5.7+/-2.6 x 10(6) microm3 (P<0.001). Mean deltaVg was 1.0 x 10(6) microm3. Patients with deltaVg<1 were considered as patients with impaired glomerular enlargement (n=29). Impaired glomerular enlargement was associated with increased acute index score in the 4-month (1.83+/-1.56 vs 1.06+/-1.48; P<0.05) and 1-year protocol biopsies (1.52+/-1.59 vs 0.62+/-1.07; P<0.05). Impaired glomerular enlargement was also associated with increased progression of chronic lesions between the 4-month and 1-year biopsy in the glomerular (0.17+/-0.38 vs 0.55+/-0.63; P<0.01), tubular (0.38+/-0.56 vs 0.83+/-0.85; P<0.01), and interstitial compartment (0.41+/-0.57 vs 0.90+/-0.86; P<0.01). The proportion of sclerotic glomeruli between both biopsies increased in patients with impaired glomerular enlargement (1.5+/-3.9 to 5.3+/-10.1, P<0.05) while it did not modify in patients with glomerular enlargement (2.1+/-7.3 vs 2.6+/-4.5; P=NS). During the first year, glomeruli enlarge but this adaptation mechanism is impaired in patients with subclinical rejection. Moreover, impaired glomerular enlargement is associated with progression of CAN.

Long-term consequences of glomerular enlargement after transplantation are not well understood. The aim is to evaluate the relationship between glomerular volume (Vg) estimated in protocol biopsies, graft function and graft survival. Vg and Banff chronic damage score were evaluated in protocol biopsies at 4 months. Creatinine clearance (CrCl) was estimated by the Cockroft-Gault formula. Vg estimated in 144 patients was 4.8 +/- 2.0 x 10(6)mu(3). It was associated with donor age (r = 0.23, p < 0.01), recipient body mass index (r = 0.17, p = 0.04), delayed graft function (Vg = 5.9 +/- 2.3 vs. 4.6 +/- 1.9 x 10(6)mu(3), p < 0.01) and CrCl (r = 0.17, p = 0.04). The best cutoff of Vg, Banff chronic damage score and CrCl was determined by Cox regression analysis, being 5.0 x 10(6)mu(3) for Vg (relative risk (RR): 2.4, 95% confidence interval (CI): 1.03-5.6), >2 for chronic damage score (RR: 3.4, 95% CI: 1.03-8.9) and 60 mL/min for CrCl (RR: 3.5, 95% CI: 1.04-11.9). These variables were independent predictors of death-censored graft survival. According to Vg and CrCl, four groups of patients were defined. Patients with small glomeruli and high CrCl had a 95% graft survival while patients with large glomeruli and low CrCl had a 45% graft survival at 15 years (p < 0.01). Large glomerular volume, high Banff chronic score and poor early renal function in stable grafts are independently associated with death-censored graft survival.

The aim of the study was to evaluate the evolution of glomerular volume 4 months after transplantation. Mean glomerular volume (Vg) was estimated according to the Weibel and Gomez method in a donor and a protocol biopsy done at 139 +/- 58 d in 41 stable grafts. Biopsies were also evaluated according to the Banff schema. Vg increased after transplantation from 4.1 +/- 1.4 to 5.1 +/- 2.4 x 10(6) micro3 (p=0.02). In patients with chronic allograft nephropathy in the protocol biopsy (n=14), the Vg enlargement was -0.3 +/-x 10(6) micro3 while in patients without chronic allograft nephropathy (n=27), glomerular enlargement was 1.6 +/- 2.1 x 10(6) micro3 (p=0.01). There was a negative association between glomerular volume in the donor biopsy and glomerular enlargement after transplantation (R=- 0.34, p=0.03). Multivariate regression analysis confirmed that Vg in the donor biopsy and chronic allograft nephropathy in the protocol biopsy were independent predictors of glomerular enlargement after transplantation (R=0.48, p=0.01). Moreover, Vg in the protocol biopsy correlated with creatinine clearance at the time of biopsy (R=0.38, p=0.01). Glomeruli enlarge after transplantation and glomerular volume after 4 months correlates with creatinine clearance, suggesting that glomerular enlargement is a necessary condition for renal adaptation to the recipient. Glomerular enlargement is impaired in patients with chronic allograft nephropathy.

Glomerular number (N(g)) is considered a major determinant of renal function and outcome. In the dog, it has been shown that Ng can be estimated with reasonable precision in vivo by means of a renal biopsy and magnetic resonance imaging (MRI). Thus, this method was applied to study anatomoclinical correlations in stable human renal transplants. Thirty-nine stable renal transplants were included. A protocol renal allograft biopsy was done at 4 mo. Biopsies were evaluated according to Banff criteria. Glomerular volume fraction (Vv(glom/cortex)) was measured by means of a point-counting method, and mean glomerular volume (V(g)) was estimated by means of Weibel and Gomez (V(g)-W&G) and maximal profile area (V(g)-MPA) methods. MRI was used to estimate renal cortical volume (V(cortex)). N(g) was calculated as (Vv(glom/cortex) x V(cortex))/V(g). GFR was estimated by the inulin clearance. Ten age-matched donor biopsies served as controls for V(g). Histologic diagnosis was as follows: normal (n = 20), borderline (n = 7), acute rejection (n = 1), and chronic allograft nephropathy (n = 11). Vv(glom/cortex) was 3.4 +/- 1.1%, V(cortex) was 167 +/- 46 cm(3), V(g)-W&G was 3.2 +/- 1.2 x 10(6) micro m(3), and V(g)-MPA was 3.3 +/- 1.0 x 10(6) micro m(3). V(g)-W&G in donor and recipient biopsies was not different (3.6 +/- 1.1 versus 3.2 +/- 1.2 x 10(6) micro m(3)). Total glomerular number estimated by means of V(g)-W&G (N(g)-W&G) was 0.73 +/- 0.33 x 10(6) and by V(g)-MPA (N(g)-MPA) was 0.74 +/- 0.31 x 10(6). A positive correlation between GFR and N(g)-W&G (r = 0.47, P = 0.002) was observed. Furthermore, the older the donor, the higher V(g)-W&G (r = 0.37, P = 0.01) and the lower N(g)-W&G (r = -0.40, P = 0.01). Total glomerular number can be estimated in stable renal allografts by means of a renal biopsy and MRI. Our data show that N(g) depends on donor age and positively correlates with GFR.