Abstract
Simple SummaryDuring their life, all living organisms defend themselves from pathogens using complex strategies. Vertebrates and invertebrates share mechanisms and molecules that guarantee their overall bodily integrity. Allograft inflammatory factor-1 (AIF-1) is a protein extensively studied in vertebrates, and especially in mammals. This factor, generally involved in inflammation events occurring upon pathogenic infection or tissue injury, is linked to several important human diseases. This review collects data on the presence and role of AIF-1 in invertebrates, which are still poorly investigated organisms. Multiple alignment and phylogenetic analysis reveal that AIF-1 is conserved in vertebrates and invertebrates, suggesting similarity of functions. In some invertebrate species, the expression of AIF-1 increases considerably after a bacterial challenge, indicating that it plays a key role during the immune responses. This review highlights the importance of studying this protein in invertebrates as a way to improve our knowledge of innate immunity mechanisms and to better understand inflammatory regulation events in mammals.Allograft inflammatory factor-1 (AIF-1) is a calcium-binding scaffold/adaptor protein often associated with inflammatory diseases. Originally cloned from active macrophages in humans and rats, this gene has also been identified in other vertebrates and in several invertebrate species. Among metazoans, AIF-1 protein sequences remain relatively highly conserved. Generally, the highest expression levels of AIF-1 are observed in immunocytes, suggesting that it plays a key role in immunity. In mammals, the expression of AIF-1 has been reported in different cell types such as activated macrophages, microglial cells, and dendritic cells. Its main immunomodulatory role during the inflammatory response has been highlighted. Among invertebrates, AIF-1 is involved in innate immunity, being in many cases upregulated in response to biotic and physical challenges. AIF-1 transcripts result ubiquitously expressed in all examined tissues from invertebrates, suggesting its participation in a variety of biological processes, but its role remains largely unknown. This review aims to present current knowledge on the role and modulation of AIF-1 and to highlight its function along the evolutionary scale.
Highlights
Living organisms protect themselves from pathogens or tissue injury through a complex regulatory network of processes, among which inflammation plays an important role [1]
The first report of Allograft inflammatory factor-1 (AIF-1) in mollusks was in Haliotis diversicolor hemocytes, where AIF-1 was one of the 34 genes involved in different cellular pathways upregulated after bacterial challenge [39]
This study demonstrates the interest of AIF-1 as a potential biomarker for environmental studies on water chemical pollution
Summary
Living organisms protect themselves from pathogens or tissue injury through a complex regulatory network of processes, among which inflammation plays an important role [1]. Biology 2020, 9, 355 cells release molecules responsible for leaking fluid from the blood vessels into the tissues. The coordinated activation of various signaling pathways regulates inflammatory mediator levels in resident tissue cells and inflammatory cells recruited from the blood [2]. In this sense, deregulated inflammatory states can drive many chronic diseases, including cardiovascular and bowel diseases, diabetes, arthritis, and cancer [3]. The authors report the involvement of this factor in allograft rejections, vasculopathies, autoimmune diseases, central nervous system (CNS) injuries, and cancers, enhancing its role as a regulator of inflammatory mediators such as iNOS, cytokines, and chemokines. A thorough understanding of ancient immune systems will help us to identify chinks in the armor of invertebrate pests and provide a window to the better comprehension of our own innate immune mechanisms
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