Aims: Emerging evidence suggests that the urinary excretion of cytokines is associated with the progression of chronic kidney disease (CKD). However, detection of urinary cytokines in high throughput is still a problem in clinical practice. In this cross-sectional study, we applied a novel proteomic technology, antibody array, to analyze urinary cytokine profiles in patients with CKD. Methods: A total of 10 subjects including 7 CKD patients and 3 normal controls were studied. These patients with CKD were divided into two groups according to the levels of estimated glomerular filtration rate (eGFR): group A (eGFR ≧80 ml/min/1.73 m², n = 3) and group B (eGFR ≤40 ml/min/1.73 m², n = 4). Urine samples taken from age and gender-matched healthy volunteers (n = 3) served as control. Differential excretion of urinary cytokines was determined by human cytokine antibody array (Raybiotech, Norcross, Ga., USA). A 2-fold change in spot intensity compared to controls was considered as significant. In order to check the reliability of the data obtained by antibody array, urinary monocyte chemoattractant protein (MCP) 1 and tumor necrosis factor (TNF) α were determined by using enzyme-linked immunosorbent assay. Results: A total of 15 cytokines varied significantly in urinary samples obtained from patients with CKD compared with normal controls. It was shown that the levels of MCP-1, RANTES, tissue inhibitor of metalloproteinase (TIMP) 1, TNF-α, vascular endothelial growth factor (VEGF), E-selectin, Fas, intercellular adhesion molecule 1, interleukin 2, matrix metalloproteinase (MMP) 2 and transforming growth factor β in patients with CKD at stage 1–2 (group A) were 2- to 5-fold higher than those in normal controls, while the excretion of MCP-1, RANTES, TIMP-1, TNF-α and VEGF was further increased in the patients with renal insufficiency (group B). However, a lower excretion of urinary vascular cell adhesion molecule 1 and platelet-derived growth factor was found in patients with CKD compared with normal controls. Impressively, the urinary MMP-9 excretion was 492-fold higher in group A and 198-fold higher in group B than that in normal controls. The levels of MCP-1 and TNF-α correlated well with the relative n-fold change seen in the antibody array experiments. The rank correlation coefficients (r values) were 0.976 (p < 0.001) and 0.939 (p < 0.001) for MCP-1and TNF-α, respectively. Conclusion: Antibody array could serve as a fast, high-throughput and sensitive tool for detecting the excretion of urinary cytokines. Our study is the first to provide an important information regarding the utility of antibody array in evaluating the role of cytokines in the initiation and progression of CKD.

Glomerulosclerosis and tubulointerstitial fibrosis are the main structural changes found in the later stages of diabetic nephropathy, which is clinically characterized by proteinuria, and progressive renal insufficiency. Heat shock protein (HSP) 47, a collagen-binding stress protein, has a specific role in the intracellular processing of procollagen molecules during collagen synthesis. It is implicated in the pathogenesis of various fibrotic diseases. However, the expression and significance of HSP47 in acute and chronic phases of diabetic nephropathy is not yet known. In this study, we studied the expression of HSP47 in the kidneys obtained from streptozotocin-induced diabetic rats, in both short- and long-term diabetes. To determine the renal expression of HSP47, and collagens (type III and IV) in acute (days 1, 3 and 14) and chronic (weeks 4, 12 and 24) diabetes, we have performed a time-course study using streptozotocin-induced diabetic rats. The expression pattern of alpha-smooth muscle actin (to identify mesangial cell damage), vimentin (to identify tubular epithelial cell damage), and desmin (to identify glomerular epithelial cell damage) was also determined in kidneys of these diabetic rats. Antibodies specific for HSP47, type III and type IV collagens, alpha-smooth muscle actin, vimentin, and desmin were used to assess the relative expression of their proteins in paraffin-embedded kidney sections by immunohistochemistry. Compared to control rat kidneys, no significant changes in the expression of HSP47 was found in the kidneys of acute diabetic rats. However a significant increase in the expression of HSP47 was noted in the kidneys of chronic diabetic rats; increased expression of HSP47 correlated with an increased renal deposition of types III and IV collagens. Similarly, compared to kidneys of control and acute diabetic rats, an increased expression of alpha-smooth muscle actin (in mesangial cells), vimentin (in tubular epithelial cells), and desmin (in glomerular epithelial cells) was detected in the kidneys of chronic diabetic rats; by dual immunostaining, these phenotypically-altered renal cells in kidneys of chronic diabetic rats were found to be HSP47-producing cells. Importantly, HSP47 up-regulation coincided with the initiation and progression of renal fibrosis, as determined by the expression and deposition of collagens. Our results strongly support a pathological role for HSP47 in the later stages (sclerotic phase) of streptozotocin-induced diabetic nephropathy, which is associated with glomerulosclerosis and tubulointerstitial fibrosis.

Cisplatin is an effective antitumor drug, but nephrotoxicity has restricted its clinical use. Renal interstitial fibrosis is a major complication of cisplatin treatment, due to the increased accumulation of extracellular matrix (ECM) proteins. Ets-1 protein plays a role in matrix remodeling by regulating matrix-degrading enzymes. We studied the role of Ets-1, matrix metalloproteinase-1 (MMP-1), and interstitial collagen (type III) in experimental cisplatin nephropathy. Wistar rats ( n = 24) were treated with cisplatin (6 mg/kg), and killed on days 3, 7, and 14, along with control rats. By immunohistochemistry, a significant increase ( P < 0.02) in the number of Ets-1-positive cells (40.09 +/- 1.52) was detected in kidneys of cisplatin-treated rats on day 3, compared with the number in control rat kidneys (29.80 +/- 0.13). The number of Ets-1-positive cells decreased in kidneys from cisplatin-treated rats on days 7 (10.93 +/- 1.20) and 14 (12.16 +/- 0.60). The expression of MMP-1 showed a similar pattern, increasing on day 3, but decreasing on days 7 and 14. The decreased levels of Ets-1 and MMP-1 were associated with increased interstitial accumulation of collagen in kidneys of cisplatin-treated rats on day 14. Molecular interactions among Ets-1, MMP-1, and type III collagens might play a role in matrix remodeling in cisplatin nephropathy.

This study clearly shows that the prevalence of renal impairment is high in acute stroke patients in China, and renal impairment may confer a significant risk for worse outcomes such as impaired neurological function and death, at least in the short term.

The molecular mechanisms of fibrosis in radiation nephropathy have received scant attention. Heat shock protein 47 (HSP47), a collagen-binding stress protein, helps in the intracellular processing of procollagen molecules during collagen synthesis. We investigated the role of HSP47 in the progression of radiation nephropathy using experimental radiation nephropathy. Experimental rat groups were as follows: (i) group I, sham operated (n = 12); (ii) group II, single doses of irradiation, either 7, 15 or 25 Gy to left kidney (n = 60); and (iii) group III, a similar irradiation procedure as group II after right nephrectomy (n = 60). The rats were followed up until 9 months after renal exposure to radiation. Renal dysfunction (as determined by serum creatinine and blood urea nitrogen) and hypertension were noted in group III rats, along with inflammatory cell infiltration and interstitial fibrosis (as determined by increased deposition of collagens). Compared to control rat kidneys, an increased expression of HSP47 was noted in kidneys obtained from irradiated rats. By double immunostaining, HSP47-expressing cells were identified as alpha-smooth muscle actin-positive myofibroblasts and vimentin-positive tubular epithelial cells. Increased expression of HSP47 was closely associated with increased deposition of collagens in the widened interstitium of irradiated rats. Overexpression of HSP47 by phenotypically altered tubulointerstitial cells might play a role in excessive assembly/synthesis of collagens and could contribute to tubulointerstitial fibrosis in radiation nephropathy.