The association of anemia and hypoalbuminemia with accelerated decline in GFR among adolescents with chronic kidney disease

We sought to describe rates of kidney function decline and to identify modifiable risk factors for CKD progression in a multicenter prospective cohort study of adolescents with CKD aged 11 to 18 years seen semiannually for up to three years. Of the 23 subjects meeting inclusion criteria, the average estimated GFR was 51 +/- 27 ml/min/1.73 m(2) (0.85 +/- 0.45 ml/s/1.73 m(2)) at entry. The overall annualized decline in GFR was 5.6 ml/min/1.73 m(2) (0.093 ml/s/1.73 m(2)) per year (95% confidence interval [95% CI]: 1.9 to 9.3 [0.032 to 0.16]). The adjusted annualized decline in GFR was found to be accelerated in males, as well as among those over 15 years of age. The adjusted annualized decline in GFR was greater among those with either anemia (hematocrit below 36%), or hypoalbuminemia (albumin below 4 g/dl [40 g/L]). After adjustment, anemia was associated with an accelerated decline of 7.8 ml/min/1.73 m(2) (0.13 ml/s/1.73 m(2)) (95% CI: 3.3 to 12 [0.055 to 0.20]) and hypoalbuminemia was associated with an accelerated decline of 17 ml/min/1.73 m(2) (0.28 ml/s/1.73 m(2)) (95% CI: 11 to 22 [0.18 to 0.37]). Further study is needed to evaluate whether treatment of anemia or hypoalbuminemia, as outlined in current clinical care guidelines for CKD, may slow the progression of CKD in adolescents.

C5b-9 and adhesion molecules in human idiopathic membranous nephropathy

BACKGROUND

Cellular immune responses and C5b-9 seem to play an important role in the pathogenesis and progression of idiopathic membranous nephropathy (IMN). The aim of the study was to investigate the role of C5b-9 and adhesion molecules in the pathogenesis of the disease.

METHODS

The clinical and pathological data of 35 patients with biopsy-proven IMN were correlated with immunohistochemical findings using monoclonal antibodies against T lymphocytes, monocytes/macrophages (MM), HLA-DR antigens, C5b-9, and adhesion molecules such as alpha3beta1, LFA-1beta, and ICAM-1.

RESULTS

In the glomeruli, C5b-9 deposits showed a significant correlation with the intensity of IgG and C3 deposition. The stage of the disease had a significant negative relationship with the glomerular alpha3beta1 expression. In the tubulointerstitium (TIN), the number of HLA-DR(+) cells was highly correlated with the numbers of total T lymphocytes, MM, and LFA-1beta(+) cells, as well as with the percentage of tubules with C5b-9 deposits. The extent of ICAM-1 expression in the TIN was significantly correlated with the numbers of interstitial MM, HLA-DR(+), and LFA-1beta(+) cells, as well as with the extent of tubular C5b-9 deposition. The severity of tubular atrophy and interstitial fibrosis had a relationship with the numbers of total T lymphocytes, MM, HLA-DR(+), and LFA-1beta(+) cells and with the extent of tubular C5b-9 deposition and ICAM-1 expression in the TIN. Serum creatinine (Scr) was highly correlated with the numbers of interstitial total T lymphocytes, MM, HLA-DR(+), and LFA-1beta(+) cells. Moreover, Scr had a significant relationship with the severity of tubular atrophy and interstitial fibrosis, as well as with the extent of tubular C5b-9 deposition and ICAM-1 expression in the TIN. Proteinuria was significantly correlated with the extent of tubular alpha3beta1 expression.

CONCLUSIONS

In IMN, C5b-9 formation may be secondary to IgG and C3 deposition. Proteinuria may contribute to the TIN damage by altering the expression of alpha3beta1 integrins in tubular cells. De novo ICAM-1 and C5b-9 expression within the TIN as well as the activated interstitial cells may be important factors leading to renal damage and renal function impairment.

Attenuating effect of a semipurified alcohol extract of soy protein on glomerular injury in spontaneous hypercholesterolemic male Imai rats

We investigated whether soy protein's alcohol-extractable components (SPEs; mainly consisting of isoflavones) have the ability to attenuate glomerular injury in male Imai rats of a spontaneous focal segmental glomerulosclerosis model. Male Imai rats were fed a casein-based diet with and without SPEs. Group 1 (Cont) was fed a standard diet without additional SPEs, and groups 2 (SPE-1) and 3 (SPE-2) were fed a standard diet supplemented with a semipurified alcohol extract of soy protein, 0.05 and 0.10 g/100 g of diet, respectively. Body weight, urinary protein level, serum constituents, and systolic blood pressure were evaluated every 4 weeks from 12 through 28 weeks of age. At 28 weeks of age, rats were studied morphologically. Growth rates were not different among the three groups throughout the experiment. SPE-supplemented diets resulted in less proteinuria and less hyperlipidemia. The decline in renal function shown by blood urea nitrogen and creatinine clearance was less marked in the animals fed the SPE-supplemented diets. Each SPE-supplemented diet equally induced less glomerular hypertrophy and less renal histological damage compared with nonsupplemented diets. The present study showed a beneficial effect of a semipurified alcohol extract of soy protein on glomerular disease.

Hypoxia stimulates proximal tubular cell matrix production via a TGF-beta1-independent mechanism

Tubulointerstitial fibrosis is characterized by tubular basement membrane thickening and accumulation of interstitial extracellular matrix (ECM). Since chronic low-grade hypoxia has been implicated in the pathogenesis of fibrosis and proximal tubular epithelial cells (PTE) are sensitive to oxygen deprivation, we hypothesized that hypoxia may stimulate ECM accumulation. In human PTE, hypoxia (1% O2, 24 hr) increased total collagen production (15%), decreased MMP-2 activity (55% +/- 13%; control = 100%) and increased tissue inhibitor of metalloproteinase-1 (TIMP-1) protein. Collagen IV mRNA levels decreased while collagen I mRNA increased, suggesting induction of interstitial collagen. Hypoxia-induced changes persisted on re-oxygenation with increased expression of TIMP mRNAs. A potential mediator for these effects is transforming growth factor-beta1 (TGF-beta1), a major pro-fibrogenic factor produced by PTE. Although hypoxia stimulated TGF-beta production (2- to 3-fold), neutralizing anti-TGF-beta1 antibody did not abolish the hypoxia-induced changes in gelatinase activity, TIMP-1, collagen IV or collagen I mRNA expression, implying that TGF-beta1 is not the mediator. Furthermore, exogenous TGF-beta1 (0 to 10 ng/ml) did not mimic hypoxia, as it stimulated MMP-2 activity and increased the expression of collagen IV, collagen I and TIMP-1 mRNA. The data suggest that hypoxia may be an important pro-fibrogenic stimulus independent of TGF-beta1.