de Martin Borst

Glomerular and tubular induction of the transcription factor c-Jun in human renal disease.

The transcription factor c‐Jun regulates the expression of genes involved in proliferation and inflammation in many cell types but its role in human renal disease is largely unclear. In the current study we investigated whether c‐Jun activation is associated with human renal disease and if c‐Jun activation regulates pro‐inflammatory and pro‐fibrotic genes in renal cells. Activation of c‐Jun was quantified by scoring renal expression of phosphorylated c‐Jun (pc‐Jun) in control human renal tissue and in biopsies from patients with various renal diseases (diabetic nephropathy, focal glomerulosclerosis, hypertension, IgA nephropathy, membranous glomerulopathy, minimal change disease, membranoproliferative glomerulonephritis, systemic lupus erythematosus, acute rejection, and Wegeners granulomatosis); this was correlated with parameters of renal damage. Furthermore, we studied the functional role of c‐Jun activation in human tubular epithelial cells (HK‐2) stimulated with TGF‐β. Activated c‐Jun was present in nuclei of glomerular and tubular cells in all human renal diseases, but only sporadically in controls. Across the diseases, the extent of pc‐Jun expression correlated with the degree of focal glomerulosclerosis, interstitial fibrosis, cell proliferation, kidney injury molecule‐1 (Kim‐1) expression, macrophage accumulation, and impairment of renal function. In HK‐2 cells, TGF‐β induced c‐Jun activation after 1 h (+40%, p < 0.001) and 24 h (+160%, p < 0.001). The specific c‐Jun N‐terminal kinase (JNK) inhibitor SP600125 abolished c‐Jun phosphorylation at all time points and blunted TGF‐β‐ or BSA‐induced procollagen‐1α 1 and MCP‐1 gene expression in HK‐2 cells. We conclude that in human renal disease, the transcription factor c‐Jun is activated in glomerular and tubular cells. Activation of c‐Jun may be involved in the regulation of inflammation and/or fibrosis in human renal disease. Copyright

Association of Complement C3 Gene Variants with Renal Transplant Outcome of Deceased Cardiac Dead Donor Kidneys

Local renal complement activation by the donor kidney plays an important role in the pathogenesis of renal injury inherent to kidney transplantation. Contradictory results were reported about the protective effects of the donor C3F allotype on renal allograft outcome. We investigated the influence of the donor C3F allotype on renal transplant outcome, taking all different donor types into account. C3 allotypes of 1265 donor–recipient pairs were determined and divided into four genotypic groups according to the C3F allotype of the donor and the recipient. The four genotypic groups were analyzed for association with primary nonfunction (PNF), delayed graft function, acute rejection, death‐censored graft survival and patient survival. Considering all donor types, multivariable analysis found no association of the donor C3F allotype with renal allograft outcome. Also, for living and deceased brain‐dead donors, no association with allograft outcome was found. Post hoc subgroup analysis within deceased cardiac dead (DCD) donors revealed an independent protective association of donor C3F allotype with PNF. This study shows that the donor C3F allotype is not associated with renal allograft outcome after kidney transplantation. Subgroup analysis within DCD donors revealed an independent protective association of the donor C3F allotype with PNF, which is preliminary and warrants further validation.

Intracellular delivery of the p38 mitogen-activated protein kinase inhibitor SB202190 [4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole] in renal tubular cells

During renal injury, activation of p38 mitogen-activated protein kinase (MAPK) in proximal tubular cells plays an important role in the inflammatory events that eventually lead to renal fibrosis. We hypothesized that local inhibition of p38 within these cells may be an interesting approach for the treatment of renal fibrosis. To effectuate this, we developed a renal-specific conjugate of the p38 inhibitor SB202190 [4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole] and the carrier lysozyme. First, we demonstrated that SB202190 inhibited the expression of albumin-induced proinflammatory (monocyte chemoattractant protein-1) and transforming growth factor (TGF)-β1-induced profibrotic (procollagen-Iα1) genes over 50% in renal tubular cells (normal rat kidney-52E). Next, we conjugated SB202190 via a carbamate linkage to lysozyme. However, this conjugate rapidly released the drug upon incubation in serum. Therefore, we applied a new platinum(II)-based linker approach, the so-called universal linkage system (ULS), which forms a coordinative bond with SB202190. The SB202190-ULS-lysozyme remained stable in serum but released the drug in kidney homogenates. SB202190-ULS-lysozyme accumulated efficiently in renal tubular cells and provided a local drug reservoir during a period of 3 days after a single intravenous injection. Treatment with SB202190-ULS-lysozyme inhibited TGF-β1-induced gene expression for procollagen-Iα1 by 64% in HK-2 cells. Lastly, we evaluated the efficacy of a single dose of the conjugate in the unilateral renal ischemia-reperfusion rat model. A reduction of intrarenal p38 phosphorylation and α-smooth muscle actin protein expression was observed 4 days after the ischemia-reperfusion injury. In conclusion, we have developed a novel strategy for local delivery of the p38 MAPK inhibitor SB202190, which may be of use in the treatment of renal fibrosis.