Invariant Natural Killer T Cell Agonist Modulates Experimental Focal and Segmental Glomerulosclerosis

A growing body of evidence demonstrates a correlation between Th2 cytokines and the development of focal and segmental glomerulosclerosis (FSGS). Therefore, we hypothesized that GSL-1, a monoglycosylceramide from Sphingomonas ssp. with pro-Th1 activity on invariant Natural Killer T (iNKT) lymphocytes, could counterbalance the Th2 profile and modulate glomerulosclerosis. Using an adriamycin(ADM)-based model of FSGS, we found that BALB/c mice presented albuminuria and glomerular degeneration in association with a Th2-like pro-fibrogenic profile; these mice also expressed a combination of inflammatory cytokines, such as IL-4, IL-1α, IL-1β, IL-17, TNF-α, and chemokines, such as RANTES and eotaxin. In addition, we observed a decrease in the mRNA levels of GD3 synthase, the enzyme responsible for GD3 metabolism, a glycolipid associated with podocyte physiology. GSL-1 treatment inhibited ADM-induced renal dysfunction and preserved kidney architecture, a phenomenon associated with the induction of a Th1-like response, increased levels of GD3 synthase transcripts and inhibition of pro-fibrotic transcripts and inflammatory cytokines. TGF-β analysis revealed increased levels of circulating protein and tissue transcripts in both ADM- and GSL-1-treated mice, suggesting that TGF-β could be associated with both FSGS pathology and iNKT-mediated immunosuppression; therefore, we analyzed the kidney expression of phosphorylated SMAD2/3 and SMAD7 proteins, molecules associated with the deleterious and protective effects of TGF-β, respectively. We found high levels of phosphoSMAD2/3 in ADM mice in contrast to the GSL-1 treated group in which SMAD7 expression increased. These data suggest that GSL-1 treatment modulates the downstream signaling of TGF-β through a renoprotective pathway. Finally, GSL-1 treatment at day 4, a period when proteinuria was already established, was still able to improve renal function, preserve renal structure and inhibit fibrogenic transcripts. In conclusion, our work demonstrates that the iNKT agonist GSL-1 modulates the pathogenesis of ADM-induced glomerulosclerosis and may provide an alternative approach to disease management

Differentiation (2002) 70:120–129 C Blackwell Verlag 2002 ORIGINAL ARTICLE

Non-thermal activation of the hsp27/p38MAPK stress pathway by mobile phone radiation in human endothelial cells: Molecular mechanism for cancer- and blood-brain barrier-related effects Accepted in revised form: 8 January 2002 Abstract We have examined whether non-thermal exposures of cultures of the human endothelial cell line EA.hy926 to 900 MHz GSM mobile phone microwave radiation could activate stress response. Results obtained demonstrate that 1-hour non-thermal exposure of EA.hy926 cells changes the phosphorylation status of numerous, yet largely unidentified, proteins. One of the affected proteins was identified as heat shock protein-27 (hsp27). Mobile phone exposure caused a transient increase in phosphorylation of hsp27, an effect which was prevented by SB203580, a specific inhibitor of p38 mitogen-activated protein kinase (p38MAPK). Also, mobile phone exposure caused transient changes in the protein expression levels of hsp27 and p38MAPK. All these changes were non-thermal effects because, as determined using temperature probes, irradiation did not alter the temperature of cell cultures, which remained throughout the irradiation period at 37 ∫ 0.3 æC. Changes in the overall pattern of protein phosphorylation suggest that mobile phone radiation activates a variety of cellular signal transduction pathways, among them the hsp27/p38MAPK stress response pathway. Based on the known functions of hsp27, we put forward the hypothesis that mobile phone radiation-induced activation of hsp27 may (i) facilitate the development of brain cancer by inhibiting the cytochrome c/caspase-3 apoptotic pathway and (ii) cause an increase in bloodbrain barrier permeability through stabilization of endo

Characterization of a rat glomerular visceral epithelial cell line

Cultures of glomerular epithelial cells (GEC) are currently used to identify important cellular and molecular mechanisms involved in the pathogenesis of renal diseases. However, there is still controversy in the literature as to the visceral or parietal origin of cultured GEC. Our aim was to firmly establish the nature of a GEC cell line. The reactivity of cultured GEC was investigated with a large panel of mono- and polyclonal antibodies by using immunofluorescent techniques and compared with literature data on the in vivo expression of these antigens on podocytes. In addition, the podocyte specific 5A (podocalyxin), 13A and 27A (9-O-acetylated GD3) antigen expression was investigated in immune-overlay experiments with isolated gangliosides and in immunoprecipitations with metabolically labelled cells. In general, immunoreactivities between cultured GEC and literature data on GEC in vivo expressions were similar. Important podocyte epitopes in vivo were expressed by cultured GEC such as podocalyxin, gp330 and the 13A antigen. Cultured GEC however differed from their in vivo counterparts in their expression of keratin-18, their lack of expression of pp44 and no detectable immunohistological expression of the ganglioside 9-O-acetylated GD3. Interestingly, the podocyte-specific epitope 9-O-acetylated GD3 was detected by the 27A antibodies in immune-overlays of isolated GEC gangliosides. Moreover, by using the 27A antibody, we were able to precipitate the podocyte-specific 103-kD protein from S-35-methionine metabolically labelled GEC. From our immunohistological data together with the detectability of the 27A antigen we conclude that the cell line we use very probably originates from glomerular visceral epithelial cells.</p