HIF-1α is functionally linked to prototypical SLC11A1-associated diseases. (A) S typhimurium infection up-regulates HIF-1α. Bone marrow–derived macrophages from wild-type (WT) or conditional HIF-1a-LysM^cre (HIF^−/−) mice were infected with Salmonella (multiplicity of infection = 10). HIF-1α expression was detected by Western blotting using β-actin expression as loading control. (B) Slc11a1 and iNOS are activated in Salmonella infection. Slc11a1 and iNOS expression was determined and compared in WT and HIF-1a-LysM^cre mice by quantitative real-time RT-PCR; expression levels were normalized to 18S ribosomal RNA levels. Fold induction is with respect to uninfected controls; data represent averages of 4 replications (means ± SEM). (C-H) Association between HIF-1α and SLC11A1 in inflammatory disease. Immunohistochemical staining of control, nonarthritic tissue with antibodies to (C) HIF-1α or (D) SLC11A1 shows that neither protein is induced or expressed in the synovium, vessels, or lymphocytes. (E) RA tissue sections were immunolabeled with anti-SLC11A1 antibody; SLC11A1 expression was detected in synovial cells (red arrows), vessels (blue arrows), and infiltrating lymphocytes (yellow arrows). (F) A × 200 magnification of panel E to show infiltrating lymphocytes stained for SLC11A1. (G) HIF-1α shows a pattern of expression that is similar to SLC11A1 expression in RA tissue sections. (H) SLC11A1 reactivity was also detected in lymphocytes in reactive sinus histiocytosis (green arrow shows reactive lymph node) but not in a control lymph node (yellow arrow). All sections were counterstained with hematoxylin. Images were acquired with a Nikon Eclipse E400 microscope using 20×/0.75 NA (panels C, D, F, and H; magnification ×200) or 10×/0.45 NA objective lenses (panels E and G; magnification ×100); They were processed with Nikon ACT-1 software version 2 and assembled with Adobe Photoshop version 7.