Effects of immune supplementation and immune challenge on oxidative status and physiology in a model bird: implications for ecologists

Abstract

SUMMARYOne route to gain insight into the causes and consequences of ecological differentiation is to understand the underlying physiological mechanisms. We explored the relationships between immunological and oxidative status and investigated how birds cope physiologically with the effects of immune-derived oxidative damage. We successively implemented two experimental manipulations to alter physiological status in a model bird species: the homing pigeon (Columba livia). The first manipulation, an immune supplementation, was achieved by oral administration of lysozyme, a naturally occurring and non-specific antimicrobial enzyme. The second manipulation, an immune challenge, took the form of an injection with lipopolysaccharide, a bacterial endotoxin. Between groups of lysozyme-treated and control birds, we compared lipopolysaccharide-induced changes in reactive oxygen metabolites, total antioxidant capacity, haptoglobin, oxygen consumption, body mass and cloacal temperature. Lysozyme supplementation intensified the lipopolysaccharide-induced inflammatory response and generated short-term oxidative and metabolic costs. We identified significant interactions between immune supplementation and immune challenge in terms of reactive oxygen metabolites, haptoglobin and oxygen consumption. Our study provides alternative interpretations of differences in oxidative and immunological indices and demonstrates that these indices can also fluctuate and interact across very short time scales, reflecting something akin to current 'health status' or 'physiological condition'. These ephemeral effects highlight the need to broadly consider current physiological condition when drawing conclusions that relate physiology to ecology and evolution.Supplementary material available online at

Eating increases oxidative damage in a reptile

“…This magnitude of eating-induced oxidative damage would presumably have important biological consequences, similar to an approximately 130% increase in ROMs due to heat stress (Costantini et al, 2012). Whereas flying 200 km or responding to an immune challenge can increase ROMs by approximately 0.27 mmol l −1 H 2 O 2 equivalents (Costantini et al, 2008b) and 0.74 mmol l −1 H 2 O 2 equivalents (van de Crommenacker et al, 2010), respectively, we detected an eatinginduced increase of over 1.25 mmol l −1 H 2 O 2 equivalents. This large increase is likely driven by increases in ROMs, rather than changes in ceruloplasmin or albumin levels, which can interfere with the kit's activity (Kilk et al, 2014; but see Colombini et al, 2016), for two reasons.…”

“…While factors that increase metabolic rate have been linked to an increase in oxidative damage (e.g. immune challenges, van de Crommenacker et al, 2010;exercise, Costantini et al, 2008b), recent work strongly suggests that increased metabolic rate per se is unlikely to drive increases in ROS and, thus, oxidative damage (reviewed in Speakman and Garratt, 2014;Salin et al, 2015).…”

Effects of immune supplementation and immune challenge on bacterial assemblages in the avian cloaca

“…We investigated whether acute systemic changes in physiology translate into measurable changes in bacterial assemblages in the avian cloaca. To do so, we used DGGE to analyze cloacal swabs that were collected from pigeons before and during a study of the effects of immune supplementation and immune challenge (van de Crommenacker et al 2010;Matson et al 2012). While these manipulations clearly affect the physiology of pigeons (van de Crommenacker et al 2010), the impacts of the same manipulations on the microbial ecology of the cloaca are unknown.…”

“…To do so, we used DGGE to analyze cloacal swabs that were collected from pigeons before and during a study of the effects of immune supplementation and immune challenge (van de Crommenacker et al 2010;Matson et al 2012). While these manipulations clearly affect the physiology of pigeons (van de Crommenacker et al 2010), the impacts of the same manipulations on the microbial ecology of the cloaca are unknown. Immune supplementation was achieved by oral administration of lysozyme, a non-specific antimicrobial enzyme that is produced endogenously by pigeons (Gavilanes et al 1982;van de Crommenacker et al 2010).…”

“…While these manipulations clearly affect the physiology of pigeons (van de Crommenacker et al 2010), the impacts of the same manipulations on the microbial ecology of the cloaca are unknown. Immune supplementation was achieved by oral administration of lysozyme, a non-specific antimicrobial enzyme that is produced endogenously by pigeons (Gavilanes et al 1982;van de Crommenacker et al 2010). Immune challenge took the form of an injection with lipopolysaccharide (LPS), a bacterial endotoxin that triggers energetically expensive febrile responses in pigeons (Nomoto 1996;van de Crommenacker et al 2010) and affects bacterial assemblages at the murine cecum (Sze et al 2014).…”