Xenopus laevis macrophage-like cells produce XCL-1, an intelectin family serum lectin that recognizes bacteria

Xenopus laevis (Daudin, 1802) as a Model Organism for Bioscience: A Historic Review and Perspective

In vitro systems have been mainly promoted by authorities to sustain research by following the 3Rs principle, but continuously increasing amounts of evidence point out that in vivo experimentation is also of extreme relevance. Xenopus laevis, an anuran amphibian, is a significant model organism in the study of evolutionary developmental biology, toxicology, ethology, neurobiology, endocrinology, immunology and tumor biology; thanks to the recent development of genome editing, it has also acquired a relevant position in the field of genetics. For these reasons, X. laevis appears to be a powerful and alternative model to the zebrafish for environmental and biomedical studies. Its life cycle, as well as the possibility to obtain gametes from adults during the whole year and embryos by in vitro fertilization, allows experimental studies of several biological endpoints, such as gametogenesis, embryogenesis, larval growth, metamorphosis and, of course, the young and adult stages. Moreover, with respect to alternative invertebrate and even vertebrate animal models, the X. laevis genome displays a higher degree of similarity with that of mammals. Here, we have reviewed the main available literature on the use of X. laevis in the biosciences and, inspired by Feymann's revised view, "Plenty of room for biology at the bottom", suggest that X. laevis is a very useful model for all possible studies.

A fibrinogen-related Lectin from Echinometra lucunter represents a new FReP family in Echinodermata phylum

Fibrinogen-related proteins (FREPs) have been identified in several animals. They are involved in the body's defense, acting as mediators of phagocytosis. Ficolins and intelectins are some of the most studied Fibrinogen-related Domain (FReD)-containing lectins. In this work, we have isolated a singular FReD-containing lectin, which cannot be classified as ficolin or intelectin. ELL (Echinometra lucunter lectin) was isolated from coelomic plasma by affinity chromatography on xanthan gum. Primary structure was determined by tandem mass spectrometry. Moreover, antimicrobial activity of ELL was evaluated against planktonic cells and biofilm of Escherichia coli, Staphylococcus aureus and S. epidermidis. ELL showed hemagglutinating activity in Ca²⁺ presence, which was inhibited by glycoprotein mucin and thyroglobulin. Complete amino acid sequence consisted of 229 residues, including a FReD in the N-terminal. Searches for similarity found that ELL was very close to putative proteins from Strongylocentrotus purpuratus. ELL showed moderate similarity with uncharacterized sea stars proteins and protochordate intelectins. ELL was able to inhibit the planktonic growth of the Gram-positive bacteria and significantly reduce the biofilm formation of all bacteria tested. In conclusion, we identified a new type of FReP-containing lectin with some structural and functional conservation towards intelectins.

Pathological Significance of Macrophages in Erectile Dysfunction Including Peyronie's Disease

Erectile function is regulated by complex mechanisms centered on vascular- and nerve-related systems. Hence, dysregulation of these systems leads to erectile dysfunction (ED), which causes mental distress and decreases the quality of life of patients and their partners. At the molecular level, many factors, such as fibrosis, lipid metabolism abnormalities, the immune system, and stem cells, play crucial roles in the etiology and development of ED. Although phosphodiesterase type 5 (PDE5) inhibitors are currently the standard treatment agents for patients with ED, they are effective only in a subgroup of patients. Therefore, further insight into the pathological mechanism underlying ED is needed to discuss ED treatment strategies. In this review, we focused on the biological and pathological significance of macrophages in ED because the interaction of macrophages with ED-related mechanisms have not been well explored, despite their important roles in vasculogenic and neurogenic diseases. Furthermore, we examined the pathological significance of macrophages in Peyronie’s disease (PD), a cause of ED characterized by penile deformation (visible curvature) during erection and pain. Although microinjury and the subsequent abnormal healing process of the tunica albuginea are known to be important processes in this disease, the detailed etiology and pathophysiology of PD are not fully understood. This is the first review on the pathological role of macrophages in PD.

Embryonic Epidermal Lectins in Three Amphibian Species, Rana ornativentris, Bufo japonicus formosus, and Cynops pyrrhogaster

Intelectins (Itlns) are secretory lectins found in several chordate species that recognize carbohydrates on the bacterial cell surface depending on Ca^{2 +} . In newly hatched larvae of Rana ornativentris (R. orn), Bufo japonicus formosus (B. jpn), and Cynops pyrrhogaster (C. pyr), an anti-Itln monoclonal antibody (mAb) labeled a subset of epidermal cells in whole-mount immunocytochemical assays. In western blot analyses, the mAb identified protein bands at approximately 33-37 kDa in the larval extracts and concentrated larval culture media. Using RT-PCR and RACE techniques, we isolated cDNAs from newly hatched larvae that encoded proteins of 343 (R. orn), 336 (B. jpn), and 337 (C. pyr) amino acids having 70%, 71%, and 60% identities with that of the Xenopus laevis embryonic epidermal lectin (XEEL), respectively. The proteins, designated REEL, BEEL, and CEEL, showed characteristics conserved among reported Itln proteins, and their amino acid sequences following the signal peptides were identical to those of the N-terminal peptides determined on Itln proteins in the respective larval extracts. Recombinant REEL (rREEL), rBEEL, and rCEEL proteins produced by HEK-293T cells were homo-oligomers of 34-37 kDa subunit peptides, which were similar to the Itlns found in the newly hatched larvae. The rEELs showed carbohydrate-binding specificities similar to that of XEEL and agglutinated Escherichia coli and Staphylococcus aureus cells depending on Ca^{2 +} . These results suggest that REEL, BEEL, and CEEL are Itlns produced and secreted by epidermal cells of R. orn, B. jpn, and C. pyr larvae, respectively, and that Itlns have a conserved role as pathogen recognition molecules in the larval innate immune system.