Antimicrobial peptides and surfactant proteins in ruminant respiratory tract disease

Abstract

In ruminants, respiratory disease is multifactorial and a leading cause of morbidity and mortality. Pulmonary innate immunity is the first line of defense for the respiratory tract. Alteration of regulation, expression, and function of these factors may be important to disease development and resolution. Many antimicrobial peptides and surfactant proteins are constitutively expressed in the respiratory tract and expression levels are regulated. Beta-defensins are cationic peptides with broad antimicrobial activity against bacterial, viral and fungal pathogens. Beta-defensins are primarily expressed in mucosal epithelia (and in some species leukocytes); where they may also participate in chemotaxis, wound repair and adaptive immune responses. Surfactant proteins A and D are secreted pulmonary surfactant proteins that have antimicrobial and immune regulatory activity. Anionic peptide is a constitutively expressed, aspartate-rich peptide that has antimicrobial activity and is most prominent during reparative epithelial hyperplasia. Regulation of these immune defense components by stress, pathogens, and inflammatory cytokines may play a role in the susceptibility to, severity and resolution of respiratory infection. The expression patterns of these molecules can be specific for hostspecies, class of pathogen and stage of infection. Understanding the regulation of antimicrobial peptide/ protein expression will further enhance the potential for novel prophylactic and therapeutic modalities to minimize the impact of respiratory disease. KeywordsAntimicrobial peptides, Surfactant proteins, Ruminant, Pneumonia Disciplines Veterinary Pathology and Pathobiology CommentsThis is an author's post-print. The final version of the article is in Veterinary Immunology and AbstractIn ruminants, respiratory disease is multifactorial and a leading cause of morbidity and mortality. Pulmonary innate immunity is the first line of defense for the respiratory tract. Alteration of regulation, expression, and function of these factors may be important to disease development and resolution. Many antimicrobial peptides and surfactant proteins are constitutively expressed in the respiratory tract and expression levels are regulated. Beta-defensins are cationic peptides with broad antimicrobial activity against bacterial, viral and fungal pathogens. Beta-defensins are primarily expressed in mucosal epithelia (and in some species leukocytes); where they may also participate in chemotaxis, wound repair and adaptive immune responses. Surfactant proteins A and D are secreted pulmonary surfactant proteins that have antimicrobial and immune regulatory activity. Anionic peptide is a constitutively expressed, aspartate-rich peptide that has antimicrobial activity and is most prominent during reparative epithelial hyperplasia. Regulation of these immune defense components by stress, pathogens, and inflammatory cytokines may play a role in the susceptibility to, severity and resolution of respiratory infection. The expression patterns of these m...

Comparison of innate immune agonists for induction of tracheal antimicrobial peptide gene expression in tracheal epithelial cells of cattle

“…Tracheal antimicrobial peptide is secreted from the respiratory epithelium in an inducible manner and has bactericidal activity against the major pathogens that cause pneumonia in cattle [1]. Other functions include antiviral effects, CCR6-dependent chemotaxis of immature dendritic cells and T lymphocytes, and epithelial cell proliferation and wound repair [38]. Prior studies have shown that LPS induces TAP gene expression, but the present findings indicate more rapid effects by stimulation of TLR2 and IL-17RA pathways.…”

Expression of select immune genes (surfactant proteins A and D, sheep beta defensin 1, and toll-like receptor 4) by respiratory epithelia is developmentally regulated in the preterm neonatal lamb

“…They have also been useful for study of RSV, parainfluenza virus-3 (PIV-3) infection and other infectious respiratory diseases [10,14]. Sheep infected with ovine RSV strains have consistency with human RSV disease including increased susceptibility in newborns, lesions, and similar innate immune genes [15][16][17]. Recently, preterm lambs were shown to have reduced RSV clearance compared to full-term lambs, which is similar to age-dependent disease seen in preterm RSV infected infants [2,3,15].…”

Failure of Respiratory Defenses in the Pathogenesis of Bacterial Pneumonia of Cattle

“…The nature of these defenses is mentioned only superficially, as these are already well described. 45,54,132,154 This analysis is supplemented where possible with comparative information from the human disease or from animal models, along with a synopsis of how the bacterial pathogens themselves have virulence attributes that allow them to evade the respiratory defenses ( Fig. 1).…”