Expression of certain HLA-I types in cleavage-stage embryos

Major histocompatibility complex-associated odour preferences and human mate choice: near and far horizons

The major histocompatibility complex (MHC) is a core part of the adaptive immune system. As in other vertebrate taxa, it may also affect human chemical communication via odour-based mate preferences, with greater attraction towards MHC-dissimilar partners. However, despite some well-known findings, the available evidence is equivocal and made complicated by varied approaches to quantifying human mate choice. To address this, we here conduct comprehensive meta-analyses focusing on studies assessing: (i) genomic mate selection, (ii) relationship satisfaction, (iii) odour preference, and (iv) all studies combined. Analysis of genomic studies reveals no association between MHC-dissimilarity and mate choice in actual couples; however, MHC effects appear to be independent of the genomic background. The effect of MHC-dissimilarity on relationship satisfaction was not significant, and we found evidence for publication bias in studies on this area. There was also no significant association between MHC-dissimilarity and odour preferences. Finally, combining effect sizes from all genomic, relationship satisfaction, odour preference and previous mate choice studies into an overall estimate showed no overall significant effect of MHC-similarity on human mate selection. Based on these findings, we make a set of recommendations for future studies, focusing both on aspects that should be implemented immediately and those that lurk on the far horizon. We need larger samples with greater geographical and cultural diversity that control for genome-wide similarity. We also need more focus on mechanisms of MHC-associated odour preferences and on MHC-associated pregnancy loss. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.

Head Transplantation: The Immune System, Phantom Sensations, and the Integrated Mind

The principal focus of this paper is to consider the implications of head and neck transplantation surgery on the issue of personal identity. To this end, it is noted that the immune system has not only been established to impose a level of self-identity on bodily cells, it has also been implicated in mental development and the regulation of mental state. In this it serves as a paradigm for the mind as the product of cephalic and extracephalic systems. The importance of bodily systems in identity is then discussed in relation to phantom tissue syndrome. The data strongly indicate that, even if surgically successful, head and neck transplantation will result in the loss of the continuity of personal identity.

Molecular Signatures of Primary Human Spermatogonial Progenitors and Its Neighboring Peritubular Stromal Compartment

In-depth understanding of human spermatogenesis requires studying specific molecular signatures and interactions of spermatogonia with other testicular cell populations, for which isolation of pure populations of different cell types is crucial. Here, we describe a technique to simultaneously enrich pure, multiple testicular cell populations, including spermatogonia, endothelial (TECs), and perivascular mesenchymal stem/stromal cells (TMSCs), from testicular tissue by flow cytometry using a combination of defined markers. Immunohistochemical studies, multicolor staining, and cell sorting followed by multiplex quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that spermatogonia were highly enriched in the CD49f⁺CD49a^-HLA-ABC^-SSEA-4⁺ fraction of primary testicular cells. In contrast to spermatogonia, TMSCs and TECs were highly enriched in the CD49f⁺CD49a⁺HLA-ABC⁺CD144^- and CD49f⁺CD49a⁺HLA-ABC⁺CD144⁺subsets, respectively. The delineation was confirmed by the expression of specific stromal and endothelial key markers as well as by the differentiation and angiogenic capacity of the sorted populations. In this article, for the first time, we performed transcriptome profiling of highly enriched, freshly isolated human spermatogonia and compared their expression profile with that of TMSCs. Our RNA sequencing data favor the hypothesis that TMSCs are candidate niche components for spermatogonia. The composite genotype and phenotype of defined testicular cell populations combined with a robust isolation procedure from small biopsies contributes to a better understanding of cellular interactions and for the establishment of efficient culture techniques to maintain spermatogonial progenitors.

Soluble ligands and their receptors in human embryo development and implantation

Extensive evidence suggests that soluble ligands and their receptors mediate human preimplantation embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human preimplantation stage embryo and female reproductive tract. The focus will be on candidates produced by the human preimplantation embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve fetal and neonatal health.

The non-classical functions of the classical complement pathway recognition subcomponent C1q

C1q, the ligand recognition subcomponent of the classical complement pathway has steadily been gaining recognition as a bridge between innate and adaptive immunity. C1q has been shown to be involved in the modulation of various immune cells (such as dendritic cells, platelets, microglia cells and lymphocytes), clearance of apoptotic cells, a range of cell processes such as differentiation, chemotaxis, aggregation and adhesion, and pathogenesis of neurodegenerative diseases and systemic lupus erythematosus. Recent studies have highlighted the importance of C1q during pregnancy, coagulation process and embryonic development including neurological synapse function. It is intriguing to note that a prototypical defence molecule has so many diverse functions that probably have its origin in its versatility as a potent charge pattern recognition molecule, modularity within the ligand-recognising globular domain, and the redundancy of putative C1q receptors. The range of function that C1q has been shown to perform also provides clues for the undiscovered functions of a number of C1q family members.