Dietary heme iron is an important nutritional source of iron in carnivores and omnivores that is more readily absorbed than non-heme iron derived from vegetables and grain. Most heme is absorbed in the proximal intestine, with absorptive capacity decreasing distally. We utilized a subtractive hybridization approach to isolate a heme transporter from duodenum by taking advantage of the intestinal gradient for heme absorption. Here we show a membrane protein named HCP 1 (heme carrier protein 1), with homology to bacterial metal-tetracycline transporters, mediates heme uptake by cells in a temperature-dependent and saturable manner. HCP 1 mRNA was highly expressed in duodenum and regulated by hypoxia. HCP 1 protein was iron regulated and localized to the brush-border membrane of duodenal enterocytes in iron deficiency. Our data indicate that HCP 1 is the long-sought intestinal heme transporter.

Blazek et al. demonstrate that treatment with IL-28A reduces inflammation in collagen-induced arthritis by restricting the recruitment of IL-1β+ neutrophils.

Collagen-induced arthritis is a well-validated, but strain-dependent mouse model of rheumatoid arthritis, with H-2(q) and H-2(r) strains showing the greatest degree of susceptibility. This protocol describes the induction of arthritis in the C57BL/6 strain (H-2(b)), which forms the genetic background of the majority of genetically modified strains. This protocol involves purification of type II collagen from chicken sternums, immunization of mice, clinical assessment of arthritis and analysis of T- and B-cell responses to type II collagen. Key aspects of the protocol are the need to use chicken collagen for immunization and the importance of avoiding aggressive behavior in males. The incidence of arthritis varies from 50 to 80% and is milder than the classical collagen-induced arthritis model. This procedure takes approximately 3 months to complete.

Most candidate drugs currently fail later-stage clinical trials, largely due to poor prediction of efficacy on early target selection 1. Drug targets with genetic support are more likely to be therapeutically valid 2,3. The translational use of genome-scale data such as from genome-wide association studies (GWAS) for drug target discovery in complex diseases remains challenging 4-6. Here we show that integration of functional genomic and immune-related annotations together with knowledge of network connectivity maximizes the informativeness of genetics for target validation, defining the target prioritization landscape for 30 immune traits at the gene and pathway level. We demonstrate how our genetics-led drug target prioritization approach ("Priority index", Pi) successfully identifies current therapeutics, predicts activity in high-throughput cellular screens (including L1000, CRISPR, mutagenesis and patient-derived cell assays), enables prioritization of under-explored targets, and determines target-level trait relationships. Pi is an open access, scalable system accelerating early-stage drug target selection for immune-mediated disease. Fang et al.

After accumulation of target cell human leukocyte antigen (HLA)-C at inhibitory natural killer (NK) cell immune synapses, some HLA-C transfers from target cells to NK cell plasma membranes and cytoplasm. This unexpected intercellular transfer of HLA-C is dependent on NK receptor recognition, since HLA-Cw6 or -Cw4 but not -Cw3 transfer to an NK transfectant expressing killer Ig-like receptor (KIR)2DL1. Strikingly, live-cell time-lapse laser scanning confocal microscopy shows vesicles containing target cell green fluorescent protein–tagged HLA-C migrating away from immune synapses into NK cells. Unlike clustering of HLA-C at the immune synapse, intercellular transfer of HLA-C is dependent on NK cell ATP, but not target cell ATP. However, the intercellular transfer of HLA-C is not dependent on active polymerization of the actin cytoskeleton. In addition, different arrangements of HLA-C are seen at inhibitory NK immune synapses, and these alter as NK synapses mature, but in a fashion distinct from that seen upon T cell activation.