Recent Advances in the Innate Immunity of Invertebrate Animals

Abstract

Invertebrate animals, which lack adaptive immune systems, have developed other systems of biological host defense, so called innate immunity, that respond to common antigens on the cell surfaces of potential pathogens. During the past two decades, the molecular structures and functions of various defense components that participated in innate immune systems have been established in Arthropoda, such as, insects, the horseshoe crab, freshwater crayfish, and the protochordata ascidian. These defense molecules include phenoloxidases, clotting factors, complement factors, lectins, protease inhibitors, antimicrobial peptides, Toll receptors, and other humoral factors found mainly in hemolymph plasma and hemocytes. These components, which together compose the innate immune system, defend invertebrate from invading bacterial, fungal, and viral pathogens. This review describes the present status of our knowledge concerning such defensive molecules in invertebrates.

Ciona intestinalis interleukin 17-like genes expression is upregulated by LPS challenge

“…They are chordate invertebrates provided by an innate immune system, including inflammatory humoral and cellular responses. The Ciona intestinalis humoral and cellular inflammatory responses have been previously reported (Parrinello and Rindone, 1981;Parrinello et al, 1984aParrinello et al, , 1984b, and, due to the knowledge of the genome (Dehal et al, 2002), this ascidian has become a model to study the evolution of immune related genes (Iwanaga and Lee, 2005;Pinto et al, 2003;Zucchetti et al, 2008). In the pharynx, that is retained the main organ of the ascidian immune system (Giacomelli et al, 2012), the LPS inoculation upregulates the transcription of hemocyte genes coding for type IX collagen-like (Vizzini et al, 2002, CAP-like (Bonura et al, 2010), MBL-like (Bonura et al, 2009), Galectins (Vizzini et al, 2012) and TNFa-like .…”

Cloning and characterization of a sialic acid binding lectins (SABL) from Manila clam Venerupis philippinarum

“…Invertebrates SABL could also mediate the innate immune response by inducing bacterial agglutination or activation of phagocytes through binding to sialic acid on foreign cells (opsonin activity) [13], for pathogenic microorganisms are known to have evolved the capacity to synthesize or capture sialic acids from their hosts and incorporate these into their own glycoconjugates [14], The SABL from Cepaea hortensis could agglutinate human erythrocytes in the presence of the divalent cations calcium, manganese or magnesium and also could interact with all strains of the group B streptococci (Streptococcus agalactiae) containing type-specific polysaccharides [15].…”

Platelets: bridging hemostasis, inflammation, and immunity

“…Hemocytes recognize foreign invaders through a number of pattern recognition and scavenger receptors [1,2]. Upon activation, subsets of hemocytes rapidly degranulate, releasing antimicrobial peptides such as big defensin, tachyplesins, and anti-LPS factor into the surrounding environment [3,4]. These molecules bind to, sequester, and kill invading pathogens.…”