Tryptophan catabolism by indoleamine 2,3-dioxygenase 1 (IDO1) plays a key role in tumoral resistance to immune rejection. In humans, constitutive expression of IDO1 has been observed in several tumor types. However, a comprehensive analysis of its expression in normal and tumor tissues is still required to anticipate the risks and potential benefits of IDO1 inhibitors. Using a newly validated monoclonal antibody to human IDO1, we performed an extensive immunohistochemical analysis of IDO1 expression in normal and tumor tissues. In normal tissues, IDO1 was expressed by endothelial cells in the placenta and lung and by epithelial cells in the female genital tract. In lymphoid tissues, IDO1 was expressed in mature dendritic cells with a phenotype (CD83 þ ,

Explants of human endometrium were cultured to study the release of matrix metalloproteinases (MMPs). Analysis of conditioned media by zymography revealed latent and active forms of co ,genase (MMP-1, EC 3.4.24.7), 72-kDa gelatinase A (MMP-2, EC 3.4.24.24), and 92-kDa gelatinase B EC 3.4.24.35). These proteinases were identified by their Mr, their inhibition by tissue inhibitor of metalloproteinases, and the activation of their zymogens by trypsin or aminophenylmer acetate. In the absence of sex hormone, explants released large a ts of enzyme activities, as measured by densitometry of zymogra or in soluble assays. Physiological concentrations of progesterone (10-200 nM) almost totally abolished the release of coilagenase, of total gelatinase activity, and of the active form of gelatinase B and largely inhibited the release of the active form of gelatinase A. These effects, which were antgoz by mifepristone (RU 38486), suggest that progesterone restrains endometrial tissue breakdown by blocking the secretion and activation of MMPs.The stroma of the human endometrium shows striking structural changes, especially during the second half of the menstrual cycle (1). If no pregnancy develops, interstitial shrinkage due to extracellular-matrix breakdown occurs and leads to hemorrhagia and mucosal shedding. The mechanisms of endometrial-tissue breakdown initiated by the fall of plasma progesterone and estradiol are still obscure. A major role of lysosomal enzymes (2) is not supported by biochemical evidence (3), whereas matrix metalloproteinases (MMPs), a family of neutral nonlysosomal enzymes, appear to be plausible agents of the remodeling of the extracellular matrix of the human endometrium (4).MMPs share similar structural domains and properties (for review, see ref. 5), are secreted as zymogens in the extracellular space, are activated by proteolytic cleavage, and are inhibited by the tissue inhibitors of metalloproteinases (TIMPs). A key feature in the regulation of extracellularmatrix degradation seems to be a fine local balance between MMPs, their activators, and their inhibitors. Interstitial collagenase (MMP-1, EC 3.4.24.7) specifically cleaves the fibrillar collagens into one-fourth and three-fourth fragments, which are susceptible to further degradation by other proteases, among which are two other MMPs, gelatinase A (MMP-2, 72 and 65 kDa, EC 3.4.24.24) and gelatinase B (MMP-9, 92 and 84 kDa, EC 3.4.24.35). Both enzymes are also able to degrade other substrates present in human endometrium (1), such as collagen types V and IV. A third subclass of MMPs has a broad spectrum of substrates and comprises stromelysin 1 (MMP-3, EC 3.4.24.17) and matrilysin EC 3.4.24.23).We have studied the possible involvement of MMPs in human endometrial remodeling, using a culture system that maintains the tissue in a similar microenvironment as in situ and responds to sex hormones for several days (3). This system allowed us to demonstrate that the human endometrium secretes collagenase and gelatinases A and B. The secr...

Cystinosis, a main cause of Fanconi syndrome, is reproduced in congenic C57BL/6 cystinosin knockout (KO) mice. To identify the sequence of pathogenic and adaptation mechanisms of nephropathic cystinosis, we defined the onset of Fanconi syndrome in KO mice between 3 and 6 months of age and analyzed the correlation with structural and functional changes in proximal tubular cells (PTCs), with focus on endocytosis of ultrafiltrated disulfide-rich proteins as a key source of cystine. Despite considerable variation between mice at the same age, typical event sequences were delineated. At the cellular level, amorphous lysosomal inclusions preceded cystine crystals and eventual atrophy without crystals. At the nephron level, lesions started at the glomerulotubular junction and then extended distally. In situ hybridization and immunofluorescence revealed progressive loss of expression of megalin, cubilin, sodiumglucose cotransporter 2, and type IIa sodium-dependent phosphate cotransporter, suggesting apical dedifferentiation accounting for Fanconi syndrome before atrophy. Injection of labeled proteins revealed that defective endocytosis in S1 PTCs led to partial compensatory uptake by S3 PTCs, suggesting displacement of endocytic load and injury by disulfide-rich cargo. Increased PTC apoptosis allowed luminal shedding of cystine crystals and was partially compensated for by tubular proliferation. We conclude that lysosomal storage triggered by soluble cystine accumulation induces apical PTC dedifferentiation, which causes transfer of the harmful load of disulfide-rich proteins to more distal cells, possibly explaining longitudinal progression of swan-neck lesions. Furthermore, our results suggest that subsequent adaptation mechanisms include lysosomal clearance of free and crystalline cystine into urine and ongoing tissue repair.