Abstract. Interactions between inflammatory infiltrates and resident tubular epithelial cells may play important roles in the development of tubulointerstitial fibrosis, by promoting epithelial cell-myofibroblast transdifferentiation (EMT). Human proximal tubular epithelial cells transdifferentiated to myofibroblasts after treatment with activated PBMC conditioned medium. mRNA and protein levels for ␣-smooth muscle actin, collagen I, and fibronectin EDA ϩ (markers for the myofibroblastic phenotype) were increased, whereas those for E-cadherin and cytokeratin 19 (markers for the epithelial phenotype) were decreased. cDNA microarray analysis was used to identify other changes in gene expression that might point to novel molecular mechanisms driving EMT. Of 1176 array genes, 61 demonstrated at least a twofold change at at least two consecutive time points, of the five time points examined (0.5, 4, 8, 16, and 48 h). Of these genes, 59% were upregulated and 41% were downregulated. The array indicated upregulation of expression of the oncostatin M (OSM)-specific receptor ␤ subunit from 4 to 48 h after exposure of kidney epithelial cells to activated PBMC conditioned medium, which contained high levels of OSM. In additional experiments, it was demonstrated that OSM induced EMT. OSM activated the Jak/Stat signaling pathway in epithelial cells, and a specific inhibitor of Jak2 blocked both its phosphorylation after exposure to OSM and the induction of ␣-actin and loss of cytokeratin 19 expression. Therefore, OSM is a novel inducer of EMT and is likely to be one of several cytokines produced by inflammatory infiltrates that contribute to this and subsequent tubulointerstitial fibrosis.

No abstract

FMS is the exclusive receptor tyrosine kinase for colony-stimulating factor-1 (CSF-1, also known as M-CSF), which regulates the survival, proliferation, differentiation, and function of macrophage lineage cells. Since CSF-1 is over-expressed in many tumors and at sites of inflammation, small molecule inhibitors of CSF-1 appear to offer an attractive strategy for reducing macrophage numbers associated with cancer as well as autoimmune and inflammatory disease, such as rheumatoid arthritis (RA). Numerous FMS inhibitors with structurally distinct chemotypes have been developed and exhibit potent in vitro activity, but only a limited number of compounds have progressed clinically due to poor selectivity. To date, only a handful of FMS inhibitors have been tested in models of metastatic bone disease and RA. This review will summarize the biology of FMS and its function in bone physiology, inflammation, immunity, and cancer. In addition, efforts directed towards identifying FMS-selective small molecule inhibitors as well as the advancement of non-selective inhibitors in the clinic will be highlighted. Furthermore, emerging monoclonal antibody-based therapeutic strategies specifically targeting M-CSF will be described.

No abstract

With the help of urinary markers, nephron segment-specific effects of chronic low-level Pb exposure could be detected in children. The pattern of effects on glomerular, proximal and distal tubular and interstitial markers was similar to that previously observed in adults. The changes, however, occur at lower b-Pb levels than in adults. The current threshold appears to be justified also from a nephrological point of view, and children can indeed be considered a special risk group.