Search

Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening syndrome characterized by platelet aggregation causing occlusive microangiopathy. It has been described as a complication in systemic lupus erythematosus (SLE). Recent research indicated that genetic or autoantibody-induced deficiency of the metalloprotease ADAMTS13 plays a key role in the pathogenesis of TTP. Here we report two uncommon cases of TTP as the first presenting symptom of SLE. Both patients were treated with combined plasma exchange and immunosuppressive therapy, and recovered completely. Although TTP and SLE have several clinical findings in common, and both disorders may coexist more frequently than we currently assume, features of one disease should not mislead to reject the alternative disorder. [ABSTRACT FROM AUTHOR]

We systematically searched for sequences influencing the expression of the mouse monocyte chemoattractant protein-1 (MCP-1) gene (Scya2) by mapping DNase I hypersensitive sites (HS) in the chromatin of mesangial cells in a 40-kb interval around the gene. We found nine HS located between -24 kb and +12.7 kb. Three HS coincided with previously known regulatory sequences (HS-2.4, HS-1.0, and HS-0.2). We tested two of the previously unknown HS located far upstream of Scya2 (HS-19.4 and HS-16.3) in transfection experiments using luciferase reporter constructs and mouse mesangial cells as recipients. In transient transfections, both HS had a moderate effect on basal promoter activity as well as promoter activity stimulated by tumor necrosis factor-alpha. In stable transfection experiments, we found much higher activity. A DNA fragment containing HS-19.4 and HS-16.3 caused a considerable increase in the number of stably integrated luciferase copies. We determined the nucleotide sequence of the 5' flanking region to -28.6 kb. Computer-assisted sequence analysis did not yield evidence of an additional gene. These HS are located within the 5' flanking region of a gene cluster consisting of Scya2 (MCP-1), Scya7 (MCP-3), Scya11 (eotaxin), Scya12 (MCP-5), and Scya8 (MCP-2). This report represents the first comprehensive chromatin analysis of the mouse MCP-1 locus leading to the identification of a complex regulatory region located far upstream of Scya2.

Glomerulonephritis frequently takes an asymptomatic course, and may lead on to chronic renal insufficiency. If clinical signs of glomerulonephritis are present, the syndrome must be characterized by means of a comprehensive diagnostic work-up. The definitive diagnosis can be established only on the basis of a renal biopsy, which also permits an assessment of the prognosis. In this review, the basic pathogenetic principles are described in brief. Taking the most important forms of glomerulonephritis--IgA nephropathy, membranous glomerulonephritis and rapidly progressive glomerulonephritis--as examples, the general therapeutic options and a number of specific treatment strategies are discussed. New facts relating to the mechanisms of glomerular damage will in future make possible the use of targeted therapeutic interventions.

Cytokine secretion by mesangial cells (MC) plays a major role in the pathogenesis of glomerulonephritis. To define signaling events that occur during the activation of MC, the cell-specific transcriptional regulation of the interleukin-6 (IL-6) gene was studied. Stimulation with lipopolysaccharide and IL-1beta resulted in the full induction of IL-6 expression only if the cells were coincubated with cAMP agonists; this effect was attenuated by protein kinase A inhibitors. In reporter gene experiments, the IL-6 promoter showed a stimulation pattern comparable to that of the endogenous gene. Elimination of individual transcription factor binding sites provided evidence for functional roles for four cis-acting elements, i.e., activator protein-1, cAMP response element-binding protein (CREB), nuclear factor for IL-6 expression (NF-IL6), and nuclear factor-kappaB (NF-kappaB). Electrophoretic mobility shift assays using nuclear extracts from MC revealed that the DNA-binding activities of activator protein-1 and NF-KB were inducible, whereas no change could be observed for CREB and NF-IL6. The presence of several transcription factor proteins, including JunB, JunD, c-Fos, Fra-1, CREB-1, activating transcription factor-2, NF-KB p50, p52, and p65, and CAAT/enhancer-binding protein-delta, was demonstrated by supershift analysis. Of particular interest was the novel finding of the participation of NF-kappaB p65 in the NF-IL6 complex. In summary, a signal transduction pathway in MC that requires protein kinase A activation in addition to a second signal provided by lipopolysaccharide or IL-1beta was identified.

The development of the technological armamentarium of molecular biology has revolutionized biomedical research in general and nephrologic investigation in particular. In addition to the recent identification of several genes involved in normal kidney function and pathologic conditions, our knowledge regarding the role of cytokines in primary renal diseases, transplant rejection, and dialysis effects has expanded greatly. In particular, molecular biologic methodology has provided insight into the mechanisms controlling cytokine gene regulation, which occurs primarily at the transcriptional level and is mediated by DNA-binding proteins interacting with specific recognition motifs in genetic promoter and enhancer elements. Interleukin-6 (IL-6) is discussed as an example because it is a secretory product of mesangial cells and participates in the cytokine network that determines glomerular and interstitial inflammation. In our analysis of IL-6 gene regulation employing reporter gene and electrophoretic mobility shift assays, we have found that bacterial lipopolysaccharide and cyclic adenosine monophosphate synergistically induce IL-6 expression in macrophages through at least four transcription factors, including AP-1, cAMP-responsive element-binding protein (CREB), NF-IL6, and NF-kappa B. One of the most exciting areas of future research will focus on transcription factor activation in experimental and clinical disease states. Novel therapeutic approaches targeting transcriptional regulation are currently being explored.

We have evaluated the potential role of prostaglandins and their second-messenger Cyclic Adenosine Monophosphate (cAMP) in the activation of interleukin-6 (IL-6) promoter regulatory elements leading to IL-6 expression in monocytic cells. We demonstrate that prostaglandins of the E series and their second-messenger cAMP induce the IL-6 promoter in the murine monocytic cell line PU5-1.8. Stimulation with both cAMP and LPS results in a marked synergistic effect. We show that the endogenous IL-6 gene is induced by cAMP as well, even though to a lesser extent than by LPS, suggesting distinctive effects of cAMP and LPS on posttranscriptional events. Mutations eliminating potential transcription factor binding sites, including the multiple-response element (MRE), AP-1, NF-IL6, and NF-kappaB binding sites, significantly reduce, but do not completely abrogate, inducibility by cAMP or prostaglandin E1, whereas alterations of four additional putative regulatory elements have no effects. In contrast, LPS-induced promoter activity is almost completely abolished by mutations in the NF-kappaB binding site, suggesting that a single regulatory element is crucial for inducibility by LPS, whereas no individual element is absolutely essential for cAMP signaling. Induction of the AP-1, NF-IL-6, and NF-kappaB elements by cAMP is correlated with the appearance of inducible factors binding to these sites, whereas factors binding to the MRE are constitutively expressed. Our results suggest that cAMP and prostaglandins act through multiple, partially redundant, regulatory elements to induce IL-6 expression in monocytic cells.