Identification and diversity of killer cell Ig-like receptors in Aotus vociferans, a New World monkey

Rhesus Macaque Activating Killer Immunoglobulin-Like Receptors Associate With Fc Receptor Gamma (FCER1G) and Not With DAP12 Adaptor Proteins Resulting in Stabilized Expression and Enabling Signal Transduction

Activating killer cell immunoglobulin-like receptors (KIR) in macaques are thought to be derived by genetic recombination of the region encoding the transmembrane and intracellular part of KIR2DL4 and a KIR3D gene. As a result, all macaque activating KIR possess a positively charged arginine residue in the transmembrane region. As human KIR2DL4 associates with the FCER1G (also called Fc receptor-gamma, FcRγ) adaptor, we hypothesized that in contrast to human and great ape the activating KIRs of macaques associate with FcRγ instead of DAP12. By applying co-immunoprecipitation of transfected as well as primary cells, we demonstrate that rhesus macaque KIR3DS05 indeed associates with FcRγ and not with DAP12. This association with FcRγ results in increased and substantially stabilized surface expression of KIR3DS05. In addition, we demonstrate that binding of specific ligands of KIR3DS05, Mamu-A1*001 and A1*011, resulted in signal transduction in the presence of FcRγ in contrast to DAP12.

Igh locus structure and evolution in Platyrrhines: new insights from a genomic perspective

Non-human primates have been used as animal models because of their phylogenetic closeness to humans. However, the genetic differences between humans and non-human primates must be considered to select the appropriate animal models. Recently, New World monkeys (Platyrrhines) have generated a higher interest in biomedical research, especially in assessing vaccine safety and immunogenicity. Given the continued and renewed interest in Platyrrhines as biomedical models, it is a necessary to have a better and more complete understanding of their immune system and its implications for research. Immunoglobulins (Ig) are the main proteins that mediate humoral immunity. These proteins have evolved as part of an adaptive immune response system derived from ancient vertebrates. There are at least four Ig classes in Prosimians, whereas five have been reported in Catarrhines. Information on the structure and evolution of the loci containing immunoglobulin heavy chain constant genes (Igh) in Platyrrhines, however, is limited. Here, Igh loci were characterized in 10 Platyrrhines using the available whole genome sequences. Human and Macaca Igh loci were also assessed to compare them with their Platyrrhines counterparts. Differences in Igh locus structure were observed between Platyrrhines and Catarrhines. Noteworthy changes occur in the γ gene, which encodes a key Ig involved in organism defense that would favor protection after vaccination. The remarkable differences between the immunoglobulin proteins of Platyrrhines and Catarrhines warrant a cautionary message to biomedical researchers.

NHP-immunome: A translational research-oriented database of non-human primate immune system proteins

We are currently living the advent of a new age for medicine in which basic research is being quickly translated into marketable drugs, and the widespread access to genomics data is allowing the design and implementation of personalized solutions to medical conditions. Non-human primates (NHP) have gained an essential role in drug discovery and safety testing due to their close phylogenetic relationship to humans. In this study, a collection of well characterized genes of the human immune system was used to define the orthology-based immunome in four NHP species, with carefully curated annotations available based on multi-tissue RNA-seq datasets. A broad variation in the frequency of expressed protein isoforms was observed between species. Finally, this analysis also revealed the lack of expression of at least four different chemokines in new-world primates. In addition, transcripts corresponding to four genes including interleukin 12 subunit alpha were expressed in humans but no other primate species analyzed. Access to the non-human primate immunome is available in http://www.fidic.org.co:90/proyecto/.

The Structure, Evolution, and Gene Expression Within the Caprine Leukocyte Receptor Complex

The leukocyte receptor complex (LRC) encodes a large number of immunoglobulin (Ig)-like receptors involved in the immune response, particularly in modulating natural killer (NK) cell function. The killer cell Ig-like receptors (KIR), the leukocyte Ig-like receptors (LILR), and a recently described novel Ig-like receptor family are highly variable between species, which is consistent with rapid evolution driven by selection pressure from pathogens. Among the species studied to date, only simians (such as humans) and bovids (such as cattle and goats) have an expanded complement of KIR genes and represent an interesting model to study KIR evolution. Using recently improved genome assemblies and an assembly of bacterial artificial chromosomes, we describe the structure of the LRC, and the KIR region in particular, in goats and compare this to sheep as the assemblies allow. These species diverged from a common ancestor ~10 million years ago and from cattle ~25 million years ago. We identified conserved KIR genes common to both goats and sheep and confirm a partial sheep haplotype shared between the Rambouillet and Texel breeds. Goats and sheep have independently expanded two novel KIR subgroups, and unlike cattle or any other mammal, they do not appear to possess a functional 3DL-lineage KIR gene. Investigation of LRC gene expression using available transcriptomic data for various sheep and goat tissues largely confirmed putative gene annotation and revealed that a relatively conserved caprinae-specific KIR subgroup is expressed in macrophages. The LILR and novel Ig-like receptors were also highly expressed across a diverse range of tissues. This further step toward our understanding of the LRC receptor repertoire will help inform future studies investigating immune response variation in these species.

Genetics of Natural Killer Cells in Human Health, Disease, and Survival

Natural killer (NK) cells have vital functions in human immunity and reproduction. In the innate and adaptive immune responses to infection, particularly by viruses, NK cells respond by secreting inflammatory cytokines and killing infected cells. In reproduction, NK cells are critical for genesis of the placenta, the organ that controls the supply of oxygen and nutrients to the growing fetus. Controlling NK cell functions are interactions of HLA class I with inhibitory NK cell receptors. First evolved was the conserved interaction of HLA-E with CD94:NKG2A; later established were diverse interactions of HLA-A, -B, and -C with killer cell immunoglobulin-like receptors. Characterizing the latter interactions is rapid evolution, which distinguishes human populations and all species of higher primate. Driving this evolution are the different and competing selections imposed by pathogens on NK cell-mediated immunity and by the constraints of human reproduction on NK cell-mediated placentation. Promoting rapid evolution is independent segregation of polymorphic receptors and ligands throughout human populations.

Co-evolution of MHC class I and variable NK cell receptors in placental mammals

Shaping natural killer (NK) cell functions in human immunity and reproduction are diverse killer cell immunoglobulin-like receptors (KIRs) that recognize polymorphic MHC class I determinants. A survey of placental mammals suggests that KIRs serve as variable NK cell receptors only in certain primates and artiodactyls. Divergence of the functional and variable KIRs in primates and artiodactyls predates placental reproduction. Among artiodactyls, cattle but not pigs have diverse KIRs. Catarrhine (humans, apes, and Old World monkeys) and platyrrhine (New World monkeys) primates, but not prosimians, have diverse KIRs. Platyrrhine and catarrhine systems of KIR and MHC class I are highly diverged, but within the catarrhines, a stepwise co-evolution of MHC class I and KIR is discerned. In Old World monkeys, diversification focuses on MHC-A and MHC-B and their cognate lineage II KIR. With evolution of C1-bearing MHC-C from MHC-B, as informed by orangutan, the focus changes to MHC-C and its cognate lineage III KIR. Evolution of C2 from C1 and fixation of MHC-C drove further elaboration of MHC-C-specific KIR, as exemplified by chimpanzee. In humans, the evolutionary trajectory changes again. Emerging from reorganization of the KIR locus and selective attenuation of KIR avidity for MHC class I are the functionally distinctive KIR A and KIR B haplotypes.