Splenic gene expression of cytokines at multiple time points following lipopolysaccharide challenge in layers.

Abstract

OBJECTIVE: To investigate inflammatory responses to lipopolysaccharide (LPS) injection in layers. ANIMALS: 33 40-week-old laying hens were used. METHODS: 30 laying hens were divided into 2 groups: the first group was injected with 8 mg/kg LPS, while the second group was injected with sterile saline. At the start of the study, 3 birds served as a baseline and were used as the time 0 controls for both the saline and LPS-treated groups. Blood and spleen tissues were collected at 0 (before) and 1, 2, 3, 4, and 6 hours after injection. RESULTS: LPS administration increased splenic mRNA levels of IL-1&#x3b2;, IL-2, IL-6, IL-8, IL-10, interferon-&#x3b3;, and tumor necrosis factor-&#x3b1; (P < .001) and serum IL-6 levels (P < .01) compared to saline injection. The mRNA expression of most cytokine genes increased rapidly toward peak values within 2 hours after the LPS injection, and then the difference between the saline and LPS treatments got smaller as time went on; serum IL-6 reached its highest concentration 2 hours after LPS administration. The magnitude of LPS-induced upregulation of gene expression was the highest for IL-6, followed by IL-1&#x3b2; and IL-8, and tumor necrosis factor-&#x3b1; was the least affected. CLINICAL RELEVANCE: The temporal and quantitative profile of these inflammatory mediators generated from this study provides valuable information in identifying the optimal time window and appropriate biomarkers for LPS-induced inflammation, which has significant implications in evaluating the effects of interventions on the immune system of chickens.