The Role of Myofibroblasts and Interstitial Fibrosis in the Progression of Membranous Nephropathy

The prognostic value of two histopathologic classification models of ANCA-associated glomerulonephritis: a prospective study

BACKGROUND

Berden Classification and anti-neutrophil cytoplasmic antibody (ANCA) Renal Risk Score are classification models for rating renal histology and predicting outcome in patients with ANCA-associated Vasculitis/Glomerulonephritis (AAV/GN). In the present study we compare their ability to predict renal function outcome in short- and long-term follow up.

METHODS

Patients with an initial diagnosis of AAV/GN based on kidney biopsy were classified according to Berden and Renal Risk Score, started on the same treatment protocol, and were followed prospectively for up to 60 months. Renal function was recorded at 3mo(T3), 6mo(T6) and 60mo(T60), and results were compared to both classification systems.

RESULTS

Ninety four AAV/GN patients, M/F = 36/58, age = 60.05 (18-82)yrs were included. Based on Berden classification, patients grouped as Focal (n = 24), Crescentic (n = 35), Mixed (n = 21) and Sclerotic (n = 14), had significant differences in estimated glomerular filtration rate (eGFR) only at T3, while the percentage of those requiring hemodialysis differed at T0, T3, T6 but not at T60. According to the Renal Risk Score, patients were classified as Low (n = 8), Medium (n = 47) and High (n = 39) risk, and showed significant differences in both eGFR levels, proportion of hemodialysis, at T0, T3, T6 and end-stage kidney disease (ESKD) at T60. Even patients classified as Mixed (Berden) and as Medium or High risk (Renal Risk Score) had significant improvement from T0 to T6. Relapse could not be predicted by either system.

CONCLUSION

Both methods were able to predict short-term renal function outcome and need for hemodialysis, but the Renal Risk Score showed significant superiority in predicting renal function outcome and ESKD after long-term follow up.

Mesenchymal transition in kidney collecting duct epithelial cells

Progressive organ damage due to tissue scarring and fibrosis is a paradigm shared by numerous human diseases including chronic kidney disease. The purpose of this study was to confirm the hypothesis that collecting duct (CD) epithelial cells can undergo mesenchymal transition (EMT) in vitro. The mechanism by which CDs undergo EMT is complex and involves both early and late cellular events. Early events include rapid insulin-like growth factor (IGF)-induced Akt and GSK-3beta phosphorylation, associated with early disruption of E-cadherin-beta-catenin membrane colocalization, with translocation of E-cadherin to endosomes, with translocation of beta-catenin to the nucleus, and with an increase in Snail expression. Transforming growth factor-beta1, on the other hand, induced early activation of Smad3 and its translocation to the nucleus, Erk1/2 phosphorylation, and early disruption of membrane E-cadherin localization. The late consequences of these events included a phenotypic transformation of the cells to a mesenchymal morphology with associated increase in vimentin and alpha-smooth muscle actin protein expression and a decrease in total cellular E-cadherin expression, detectable as early as 24 h after stimulation.

Relationship Between Clinical Predictors and Tubulointerstitial Damage in Adult-onset Primary Nephrotic Syndrome

BACKGROUND

Tubulointerstitial damage (TID) is an important mediator in the progression of chronic proteinuric nephropathies. Our aim in this study was to evaluate the relationship between several clinical predictors and TID in adult-onset primary nephrotic syndrome in China.

METHODS

One hundred ninety-five adult inpatients who were diagnosed with primary nephrotic syndrome based on clinical presentation and biopsy results were enrolled in this study from March 2003 to September 2005. The degree of TID was graded by a semiquantitative method including <2 score and >or=2 score.

RESULTS

In all patients, the rate of glomerulosclerosis was correlated with the severity of TID. Serum creatinine and uric acid (r = 0.183, p = 0.012 and r = 0.377, p = 0.00001, respectively) but not serum lipid or total 24-h urinary protein were related with TID. In 64 patients, urinary excretion of IgG (r = 0.443, p = 0.00001) but not of albumin, transferrin, retinal-binding protein, or alpha1-microglobulin were significantly associated with the extent of TID. Proteinuria selectivity index based upon IgG also correlated significantly with the extent of TID (p = 0.0001) (score 0-1 vs. score >or=2).

CONCLUSIONS

These results showed that serum creatinine and uric acid, the excretion of urinary IgG and proteinuria selectivity index based upon IgG, were highly correlated with the severity of TID in adult-onset primary nephrotic syndrome. These clinical parameters might be useful for predicting the development and progression of proteinuric nephropathy as independent risk factors.