About this Research Topic
Recent years have also witnessed an enormous increase in our knowledge of FcRn functions beyond its well-characterized role in half-life regulation, as it transports IgG within and across many different cell types in the body, such as endothelial cells, cells of the placenta, mucosal epithelial cells, kidney cells, liver cells and dendritic cells. In dendritic cells, FcRn is engaged in orchestration and delivery of IgG bound antigens to processing pathways that promote presentation on MHC class II molecules and cross-presentation on MHC class I molecules, while unbound IgG is recycled and rescued, like in endothelial cells lining the blood vessels. Moreover, expression of FcRn has been identified in many other tissues, including the blood-brain barrier, the glomerular filters of the kidneys and the liver. These findings merit further studies on the diverse roles of FcRn at these body sites.
Beside IgG, FcRn binds albumin, which is also protected from intracellular degradation. While IgG combats infections, and is produced by plasma cells, albumin is exclusively produced by hepatocytes and serves as a multi-transporter that fulfils essential roles as a carrier of an array of nutrients,
hormones, drugs and toxins throughout the body. Albumin is the most abundant protein in blood due to the rate of synthesis and its interaction with FcRn.
Importantly, since IgG and albumin are extensively explored as therapeutics or carrier of drugs, there is an intense interest in engineering of novel variants with modulated FcRn binding kinetics tailored for improved pharmacokinetics and therapeutic efficacy. FcRn is a major histocompatibility complex (MHC) class I-related receptor, and knowledge of how FcRn binds both its ligands and ligand variants is of great importance.
In this research topic, we aim to provide a comprehensive state-of the art overview of current research on the versatile functions of FcRn, and encourage submission of research articles, reviews and perspectives. Considering the clinical significance of FcRn, we also aim to provide a range of articles summarizing the current knowledge on how our understanding of FcRn functions that can be translated into development of new therapeutics.
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