Heme carrier protein (HCP-1) spatially interacts with the CD163 hemoglobin uptake pathway and is a target of inflammatory macrophage activation

Macrophages constitute the major cellular compartment for hemoglobin (Hb) degradation and subsequent recycling of heme-iron to erythropoiesis. Dysregulation of macrophage iron and heme metabolism is a major pathophysiologic determinant of anemia of chronic disease. In this study, we show that the heme transporter heme carrier protein 1 (HCP-1) is expressed in human macrophages. Within early endosomes, HCP-1 colocalizes with endocytosed Hb-haptoglobin (Hp) complexes, which are taken up via the CD163 scavenger receptor pathway. Hb-Hp passes the divalent metal transporter 1B/HCP-1-positive endosomal compartment on its route from the cell surface to lysosomes. HCP-1 mRNA and protein expression are down-regulated by stimulation of macrophages with various TLR agonists and IFN-gamma. The profound suppression of HCP-1 expression by inflammatory macrophage activation parallels the regulation of the iron exporter ferroportin. In contrast, dexamethasone enhanced HCP-1 expression significantly. Given the spatial relationship, we propose that the Hb scavenger receptor CD163 and HCP-1 constitute a linked pathway for Hb catabolism and heme-iron recycling in human macrophages.     

Induction of human CD4+ regulatory T cells by mycophenolic acid-treated dendritic cells

Depending on their degree of maturation, costimulatory molecule expression, and cytokine secretion, dendritic cells (DC) can induce immunity or tolerance. DC treated with mycophenolic acid during their maturation (MPA-DC) have a regulatory phenotype and may therefore provide a new approach to induce allograft tolerance. Purified CD4(+) T cells stimulated in a human in vitro model of mixed culture by allogeneic MPA-DC displayed much weaker proliferation than T cells activated by mature DC and were anergic. This hyporesponsiveness was alloantigen-specific. Interestingly, T cells stimulated by MPA-DC during long-term coculture in four 7-day cycles displayed potent, suppressive activity, as revealed by marked inhibition of the proliferation of naive and preactivated control T cells. These regulatory T cells (Tregs) appeared to have antigen specificity and were contact-dependent. Tregs induced by MPA-DC were CD25(+)glucocorticoid-induced TNFR(+)CTLA-4(+)CD95(+), secreted IL-5 and large amounts of IL-10 and TGF-beta, and displayed enhanced forkhead box p3 expression. These results obtained in vitro demonstrate that human MPA-DC can induce allospecific Tregs that may be exploited in cell therapy to induce allograft tolerance.     

Identification of p53-dependent genes potentially involved in UVB-mediated premature senescence of human skin fibroblasts using siRNA technology

Premature senescence of skin human diploid fibroblasts is induced after a series of 10 sublethal exposures to UVB at 2.5 kJ/m(2) with appearance of several biomarkers of cellular senescence like senescence-associated beta-galactosidase activity (SA beta-gal) and cell cycle arrest. Herein it is shown that the induction of UVB-induced premature senescence is associated with a transient increase of protein abundance and DNA-binding activity of p53. Silencing p53 expression with small interfering RNA (siRNA) affected the basal level of SA beta-gal and proliferative potential, but did not prevent UVB-induced increase of SA beta-gal and decrease of DNA synthesis. We used a senescence-specific low-density DNA array and p53 siRNA to study the mRNA abundance of 240 senescence-related genes and identified several potential p53-dependent genes differentially expressed after the repeated exposures to UVB.     

Universal cell labelling with anionic magnetic nanoparticles

Magnetic labelling of living cells creates opportunities for numerous biomedical applications, from individual cell manipulation to MRI tracking. Here we describe a non-specific labelling method based on anionic magnetic nanoparticles (AMNPs). These particles first adsorb electrostatically to the outer membrane before being internalized within endosomes. We compared the labelling mechanism, uptake efficiency and biocompatibility with 14 different cell types, including adult cells, progenitor cells, immune cells and tumour cells. A single model was found to describe cell/nanoparticle interactions and to predict uptake efficiency by all the cell types. The potential impact of the AMNP label on cell functions, in vitro and in vivo, is discussed according to cellular specificities. We also show that the same label provides sufficient magnetization for MRI detection and distal manipulation.     

Primary clear cell meningioma of the orbit mimicking a metastatic carcinoma: usefulness of immunohistochemistry and cytogenetic analysis

Clear cell meningiomas (CCM) are rare tumors of the nervous system that usually occur in young patients and display high recurrence rates and potentially aggressive behavior. In this report, we describe a primary CCM of the orbit in an 84-year-old man with a previous history of a clear cell carcinoma of the kidney. Histologically, the tumor demonstrated a sheet-like proliferation of clear polygonal cells. Differential diagnosis includes metastasis of clear cell carcinomas. Immunohistochemistry, by showing that tumor cells expressed vimentin, epithelial membrane antigen, and progesterone antigens, and cytogenetic analysis, by identifying a monosomy 22, confirmed the diagnosis of CCM.     

Quality control assessment of human immunodeficiency virus type 2 (HIV-2) viral load quantification assays: results from an international collaboration on HIV-2 infection in 2006

Human immunodeficiency virus type 2 (HIV-2) RNA quantification assays used in nine laboratories of the ACHI(E)V(2E) (A Collaboration on HIV-2 Infection) study group were evaluated. In a blinded experimental design, laboratories quantified three series of aliquots of an HIV-2 subtype A strain, each at a different theoretical viral load. Quantification varied between laboratories, and international standardization of quantification assays is strongly needed.     

Antitumoral activity and osteogenic potential of mesenchymal stem cells expressing the urokinase-type plasminogen antagonist amino-terminal fragment in a murine model of osteolytic tumor

Prostate cancer metastasis to bone results in mixed osteolytic and osteoblastic lesions associated with high morbidity, and there is mounting evidence that the urokinase-type plasminogen system is causatively involved in the progression of prostate cancer. Adult mesenchymal stem cells (MSCs) are promising tools for cell-mediated gene therapy with the advantage of osteogenic potential, a critical issue in the case of osteolytic metastases. In this study, we evaluated the therapeutic use of engineered murine MSCs for in vivo delivery of the urokinase-type plasminogen antagonist amino-terminal fragment (hATF) to impair osteolytic prostate cancer cell progression in bone and to repair bone lesions. Bioluminescence imaging revealed that both primary MSCs and the MSC line C3H10T1/2 (C3) expressing hATF (MSC-hATF) significantly inhibited intratibial PC-3 Luciferase (Luc) growth following coinjection in SCID mice. Furthermore, microcomputed tomography imaging of vascular network clearly demonstrated a significant decrease in tumor-associated angiogenesis and a protection from tumor-induced osteolysis in MSC-hATF-treated mice. Importantly, the osteogenic potential of MSC-hATF cells was unaffected, and an area of new bone formation was evidenced in 60% of animals. Together, these data support the concept of MSC-based therapy of tumor osteolysis disease, indicating that MSCs may combine properties of vehicle for angiostatic agent with osteogenic potential. Disclosure of potential conflicts of interest is found at the end of this article.