SummaryImmunohistochemical methods were used to search for Fas receptor/Fas ligand system involvement in multiple sclerosis (MS) white matter brain lesions. We found large numbers of Fas ligand (Fas-L)-bearing cells present in two acute lesions and 12 of 16 chronic MS lesions, and very few positive cells in non-inflammatory controls. Four of six brains from non-MS neuropathologic conditions associated with inflammation and white matter disease were, however, also positive for Fas-L. Double staining with cell-specific markers revealed that the pattern of ligand-positive cells in chronic MS lesions was complex and composed of several different cell types which were primarily resident glial cells with a small overlay ofmacrophages. Fas/APO 1 (CD95) receptor expression in MS tissue was also evaluated and marked upregulation of the receptor was found. In addition, Fas receptor was induced, but to a lesser extent, in numerous control brains. The observations that TUNEL-positive dying cells were present in MS lesions and showed excellent co-localization with Fas-L, indicate that the Fas death system may contribute to plaque pathogenesis and could lead to the development of a new category of therapeutic agents for MS.

Although multidrug-resistance-associated protein-1 (MRP1) is a major contributor to multi-drug resistance (MDR), the regulatory mechanism of Mrp1 still remains unclear. Nrf2 is a transcription factor that regulates cellular defense response through antioxidant response elements (AREs) in normal tissues. Recently, Nrf2 has emerged as an important contributor to chemo-resistance in tumor tissues. In the present study, the role of Nrf2-ARE pathway on regulation of Mrp1 was investigated. Compared with H69 lung cancer cells, H69AR cells with MDR showed significantly higher Nrf2-ARE pathway activity and expression of Mrp1 as well. When Nrf2 was knocked down in H69AR cells, MRP1's expression decreased accordingly. Moreover, those H69AR cells with reduced Nrf2 level restored sensitivity to chemo-drugs. To explore how Nrf2-ARE pathway regulates Mrp1, the promoter of Mrp1 gene was searched, and two putative AREs—ARE1 and ARE2—were found. Using reporter gene and ChIP assay, both ARE1 and ARE2 showed response to and interaction with Nrf2. In 40 cases of cancer tissues, the expression of Nrf2 and MRP1 was measured by immunohistochemistry (IHC). As the quantitive data of IHC indicated, both Nrf2 and MRP1 showed significantly higher expression in tumor tissue than adjacent non-tumor tissue. And more important, the correlation analysis of the two genes proved that their expression was correlative. Taken together, theses data suggested that Nrf2-ARE pathway is required for the regulatory expression of Mrp1 and implicated Nrf2 as a new therapeutic target for MDR.

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3, 5-Diiodothyronine (T2), a natural metabolite of triiodothyronine (T3) from deiodination pathway, can mimic biologic effects of T3 without inducing thyrotoxic effects. Recent studies revealed T3 acted as a protective factor against diabetic nephropathy (DN). Nevertheless, little is known about the effect of T2 on DN. This study was designed to investigate whether and how T2 affects experimental models of DN in vivo and in vitro. Administration of T2 was found to prevent significant decrease in SIRT1 protein expression and activity as well as increases in blood glucose, urine albumin excretion, matrix expansion, transforming growth factor-β1 expression, fibronectin and type IV collagen deposition in the diabetic kidney. Concordantly, similar effects of T2 were exhibited in the cultured rat mesangial cells (RMC) exposed to high glucose and that could be abolished by a known SIRT1 inhibitor, sirtinol. Moreover, enhanced NF-κB acetylation and JNK phosphorylation present in both diabetic rats and high glucose-treated RMC were distinctly dampened by T2. Collectively, these results suggested that T2 was a protective agent against renal damage in diabetic nephropathy, whose action involved regulation of SIRT1.

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