AUTHOR=Liu Wen-Chao , Huang Meng-Yi , Balasubramanian Balamuralikrishnan , Jha Rajesh 

TITLE=Heat Stress Affects Jejunal Immunity of Yellow-Feathered Broilers and Is Potentially Mediated by the Microbiome

JOURNAL=Frontiers in Physiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2022.913696

DOI=10.3389/fphys.2022.913696

ISSN=1664-042X

ABSTRACT=<p>In the perspective of the global climate change leading to increasing temperature, heat stress (HS) has become a severe issue in broiler production, including the indigenous yellow-feathered broilers. The present study aimed to investigate the effects of HS on jejunal immune response, microbiota structure and their correlation in yellow-feathered broilers. A total of forty female broilers (56-days-old) were randomly and equally divided into normal treatment group (NT group, 21.3 ± 1.2°C, 24 h/day) and HS group (32.5 ± 1.4°C, 8 h/day) with five replicates of each for 4 weeks feeding trial. The results showed that HS exposure increased the contents of TNF-α, IL-1β, and IL-6 in jejunal mucosa (<italic>p</italic> &lt; 0.05). The HS exposure up-regulated the relative fold changes of <italic>NF-κB, TNF-α, IL-1β,</italic> and <italic>IL-6</italic> (<italic>p</italic> &lt; 0.01) while down-regulated the relative fold change of <italic>IFN-γ</italic> in jejunal mucosa (<italic>p</italic> &lt; 0.05)<italic>.</italic> Meanwhile, HS had no significant impacts on alpha diversity of jejunal microbiota such as Simpson, Chao1 richness estimator (Chao 1), abundance-based coverage estimators (ACE), and Shannon index (<italic>p</italic> &gt; 0.10). Broilers exposed to HS reduced the jejunal microbial species number at the class and order level (<italic>p</italic> &lt; 0.05). Moreover, HS decreased the relative abundance of <italic>Ruminococcus</italic>, <italic>Bdellovibrio,</italic> and <italic>Serratia</italic> at the genus level in jejunum (<italic>p</italic> &lt; 0.05). At the phylum level, four species of bacteria (<italic>Bacteroidetes, Cyanobacteria, Thermi,</italic> and <italic>TM7</italic>) were significantly associated with immune-related genes expression (<italic>p</italic> &lt; 0.05). At the genus level, ten species of bacteria were significantly correlated with the expression of immune-related genes (<italic>p</italic> &lt; 0.05), including <italic>Caulobacteraceae, Actinomyces, Ruminococcaceae, Thermus, Bdellovibrio, Clostridiales, Sediminibacterium, Bacteroides, Sphingomonadales</italic> and <italic>Ruminococcus</italic>. In particular, the microbial with significantly different abundances, <italic>Ruminococcus</italic> and <italic>Bdellovibrio</italic>, were negatively associated with pro-inflammatory cytokines expression (<italic>p</italic> &lt; 0.05). These findings demonstrated that HS exposure promoted the production of pro-inflammatory cytokines in yellow-feathered broilers’ jejunum. The detrimental effects of HS on jejunal immune response might be related to dysbiosis, especially the reduced levels of <italic>Ruminococcus</italic> and <italic>Bdellovibrio</italic>.</p>