Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA.
Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA.
Mol Ecol. 2024 Jul;33(14):e17428. doi: 10.1111/mec.17428. Epub 2024 Jun 5.
Macronutrients play a vital role in host immunity and can influence host-pathogen dynamics, potentially through dietary effects on gut microbiota. To increase our understanding of how dietary macronutrients affect physiology and gut microbiota and investigate whether feeding behaviour is influenced by an immune threat, we conducted two experiments. First, we determined whether zebra finches (Taeniopygia guttata) exhibit shifts in physiology and gut microbiota when fed diets differing in macronutrient ratios. We found the type and amount of diet consumed affected gut microbiota alpha diversity, where microbial richness and Shannon diversity increased with caloric intake in birds fed a high-fat diet and decreased with caloric intake in birds fed a high protein diet. Diet macronutrient content did not affect physiological metrics, but lower caloric intake was associated with higher complement activity. In our second experiment, we simulated an infection in birds using the bacterial endotoxin lipopolysaccharide (LPS) and quantified feeding behaviour in immune challenged and control individuals, as well as birds housed near either a control pair (no immune threat), or birds housed near a pair given an immune challenge with LPS (social cue of heightened infection risk). We also examined whether social cues of infection alter physiological responses relevant to responding to an immune threat, an effect that could be mediated through shifts in feeding behaviour. LPS induced a reduction in caloric intake driven by a decrease in protein, but not fat consumption. No evidence was found for socially induced shifts in feeding behaviour, physiology or gut microbiota. Our findings carry implications for host health, as sickness-induced anorexia and diet-induced shifts in the microbiome could shape host-pathogen interactions.
宏量营养素在宿主免疫中起着至关重要的作用，并且可以通过饮食对肠道微生物群的影响来影响宿主-病原体动态。为了增加我们对饮食宏量营养素如何影响生理和肠道微生物群的理解，并研究喂养行为是否受到免疫威胁的影响，我们进行了两项实验。首先，我们确定了斑胸草雀（Taeniopygia guttata）在喂食不同宏量营养素比例的饮食时是否会在生理和肠道微生物群中发生变化。我们发现，所消耗的饮食类型和数量会影响肠道微生物群的α多样性，其中微生物丰富度和香农多样性随着高脂肪饮食中鸟类摄入的热量增加而增加，而随着高蛋白饮食中鸟类摄入的热量减少而减少。饮食宏量营养素含量不会影响生理指标，但较低的热量摄入与较高的补体活性相关。在我们的第二项实验中，我们使用细菌内毒素脂多糖（LPS）模拟鸟类感染，并量化了免疫挑战和对照个体的喂养行为，以及饲养在对照鸟（无免疫威胁）附近或饲养在接受 LPS 免疫挑战鸟（感染风险增加的社交线索）附近的鸟的喂养行为。我们还研究了感染的社交线索是否会改变与应对免疫威胁相关的生理反应，这种影响可能是通过喂养行为的改变来介导的。LPS 诱导的热量摄入减少是由蛋白质而不是脂肪消耗减少驱动的。没有发现社交诱导的喂养行为、生理或肠道微生物群变化的证据。我们的研究结果对宿主健康具有重要意义，因为疾病引起的厌食和饮食引起的微生物组变化可能会影响宿主-病原体相互作用。
