Short communication: Characterizing ovine serum stress biomarkers during endotoxemia

Abstract

Breeding stress-resilient livestock is a potential strategy to help mitigate the negative effect of environmental and pathogenic stressors. The hypothalamic-pituitaryadrenal axis and immune system are activated during stress events and release mediators into the circulation that help restore physiological homeostasis. The purpose of this study was to assess a comprehensive set of circulatory mediators released in response to an acute immune stress challenge to identify candidate biomarkers that can be used for the selection of stress-resilient animals. Fifteen female lambs were stress challenged with an intravenous bolus of lipopolysaccharide (LPS; 400 ng/kg), and blood was collected from the jugular vein at 0, 2, 4, and 6 h after LPS challenge to identify and monitor candidate stress biomarkers; temperature was also recorded over time. Biomarker responses were evaluated with a repeated-measures model to compare time points with baseline values. As expected, all sheep had a monophasic febrile response to LPS challenge, and cortisol increased and returned to baseline by 6 h. The cytokines tumor necrosis factor-α, IL-6, IFN-γ (proinflammatory), and IL-10 (anti-inflammatory) increased, but only tumor necrosis factor-α returned to baseline during the monitoring period. The cytokines IL-1α, IL-1β, IL-17α (proinflammatory), and IL-4 (anti-inflammatory) did not respond to LPS challenge. All chemokines (CCL2, CCL3, CCL4, CXCL10, and IL-8) responded to LPS challenge; however, only CCL2, CCL3, CCL4, and CXCL10 increased over time, and only CCL3, CCL4, and CXCL10 returned to baseline during the monitoring period. MicroRNA (miR-145, miR-233, and miR-1246) also increased and remained elevated during the study. In summary, the LPS challenge induced a strong stress response in Rideau-Dorset sheep that could be monitored with a distinct profile of circulatory biomarkers.

Identification of Ovine Serum miRNAs Following Bacterial Lipopolysaccharide Challenge

“…A complementary mechanism of both pro-and anti-inflammatory immune responses was observed in present investigation which is likely regulated in part by the identified DE miRNAs. A similar balance of pro-and anti-inflammatory activities was reported in these same lambs at the protein level in our previous study [6].…”

“…This PAMP contributes to several livestock pathologies, including mastitis [1], acidosis [2], and gut leakage due to heat stress [3]; and human pathologies, such as systematic inflammatory response syndrome and sepsis [4]. Our previous studies have utilized E. coli LPS as an acute stressor of sheep to characterize the stress response and determine the genetic contribution to variation in the stress response [5][6][7]. Several other reports have provided evidence of varying immune responses amongst sheep breeds, indicating varied genetic regulation of the innate and adaptive immune systems [8][9][10].…”

“…Accumulating evidence suggests that differential expressions of circulatory miRNAs in vivo can reflect the status of physiological changes and serve as biomarkers for diverse physiological and pathological conditions [15,16]. The potency of LPS for inducing a systemic inflammatory response has been documented via assessment of aberrant changes in miRNA expression [6,17], thereby suggesting that LPS is suitable for examining the involvement of miRNA in regulating the acute phase response. Therefore, the present study aimed to investigate the expression patterns of ovine circulating miRNAs at the peak cortisol response during acute systemic LPS challenge; these miRNAs could be used as stress biomarkers for livestock and may help to better understand coordinated cross-talk between the neuroendocrine and immune systems.…”

MicroRNAs as Biomarkers for Animal Health and Welfare in Livestock

“…Immunity C-miRNAs have been proposed as biomarkers in the interaction between the HPA axis and stress-activated immune responses (93). A strong stress response in sheep was correlated with distinct circulatory biomarker profiles, demonstrating that stress resiliency may be determined by specific circulatory patterns.…”

“…A strong stress response in sheep was correlated with distinct circulatory biomarker profiles, demonstrating that stress resiliency may be determined by specific circulatory patterns. The inflammatory response, detected through the measurement of immune and stress biomarkers, was associated with high expression levels of miR-145, miR-233, and miR-1246 (93).…”