Innate and adaptive immune proteins in the preen gland secretions of male house sparrows

Diana Carneiro,Melissah Rowe,Gábor Árpád Czirják

doi:10.1111/jav.02556

Abstract

Recent studies have demonstrated that preen oil acts to reduce or eliminate feather‐associated bacteria. The mechanisms underlying this antibacterial activity, however, are incompletely understood. In addition to the activity of alcohols (i.e. 3,7‐dimethyloctan‐1‐ol), recent research has suggested that antimicrobial peptides may underlie the antibacterial activity of preen oil. Here, we document the presence of innate and adaptive immune proteins, lysozyme and immunoglobulin Y (IgY), in the preen oil of house sparrowsPasser domesticus. We suggest lysozyme functions as an antimicrobial agent, with potentially important impacts against Gram‐positive feather degrading bacteria. Furthermore, both lysozyme and IgY likely act in local immune defence of the preen gland, and may also play a role in regulating the local microbiome, with potentially important consequences for chemical communication and signalling. Our findings suggest that the preen gland and its secretions should be considered an integral part of the body's first line of defence against invading infections.

Highlights

Organisms are constantly exposed to a range of microorganisms in their environment, some of which may have detrimental impacts on their hosts (Steinert et al 2000)
To the best of our knowledge, this is the first demonstration of immune defence proteins in avian preen oil
Our study builds on these earlier works by demonstrating that the antimicrobial peptide lysozyme contributes to the antimicrobial activity of preen oil in house sparrows

Summary

Introduction

Organisms are constantly exposed to a range of microorganisms in their environment, some of which may have detrimental impacts on their hosts (Steinert et al 2000). To counteract the potentially negative effects of these microorganisms, animals have evolved a range of behavioural, mechanical and chemical defences to impede or defeat invading parasites and pathogens (Ganz 2002, Proksch et al 2008, Gallo and Hooper 2012). The skin and mucosa provide a physical barrier to microbial invasion and, as such, act as the first line of defence against infectious agents These barriers may exhibit structures that incorporate specialised cells that secrete defence molecules (e.g. antimicrobial proteins) and play a role in local chemical defence. Such molecules can contribute to systemic immunity (Diamond et al 2009), and are a important component of animal immune defences.

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Conclusion