Acute systemic inflammatory response to lipopolysaccharide stimulation in pigs divergently selected for residual feed intake

Abstract

Background It is unclear whether improving feed efficiency by selection for low residual feed intake (RFI) compromises pigs’ immunocompetence. Here, we aimed at investigating whether pig lines divergently selected for RFI had different inflammatory responses to lipopolysaccharide (LPS) exposure, regarding to clinical presentations and transcriptomic changes in peripheral blood cells. Results LPS injection induced acute systemic inflammation in both the low-RFI and high-RFI line (n = 8 per line). At 4 h post injection (hpi), the low-RFI line had a significantly lower (p = 0.0075) mean rectal temperature compared to the high-RFI line. However, no significant differences in complete blood count or levels of several plasma cytokines were detected between the two lines. Profiling blood transcriptomes at 0, 2, 6, and 24 hpi by RNA-sequencing revealed that LPS induced dramatic transcriptional changes, with 6296 genes differentially expressed at at least one time point post injection relative to baseline in at least one line (n = 4 per line) (|log2(fold change)| ≥ log2(1.2); q < 0.05). Furthermore, applying the same cutoffs, we detected 334 genes differentially expressed between the two lines at at least one time point, including 33 genes differentially expressed between the two lines at baseline. But no significant line-by-time interaction effects were detected. Genes involved in protein translation, defense response, immune response, and signaling were enriched in different co-expression clusters of genes responsive to LPS stimulation. The two lines were largely similar in their peripheral blood transcriptomic responses to LPS stimulation at the pathway level, although the low-RFI line had a slightly lower level of inflammatory response than the high-RFI line from 2 to 6 hpi and a slightly higher level of inflammatory response than the high-RFI line at 24 hpi. Conclusions The pig lines divergently selected for RFI had a largely similar response to LPS stimulation. However, the low-RFI line had a relatively lower-level, but longer-lasting, inflammatory response compared to the high-RFI line. Our results suggest selection for feed efficient pigs does not significantly compromise a pig’s acute systemic inflammatory response to LPS, although slight differences in intensity and duration may occur.

A Proteomic Approach to Elucidate the Changes in Saliva and Serum Proteins of Pigs with Septic and Non-Septic Inflammation

“…Another cause for concern is the balance between the benefits obtained from the study of the pathophysiology of sepsis and the well-being of the animals implicated in these experimental models [ 15 ]. However, LPS administration is considered an adequate model in pigs to study the pathophysiology of inflammation, immune system [ 13 , 16 , 17 ], and changes in biomarkers of oxidative status [ 18 ] associated with sepsis.…”

Analysis of merged whole blood transcriptomic datasets to identify circulating molecular biomarkers of feed efficiency in growing pigs

“…Peripheral blood is widely used in human medicine and veterinary fields as a relevant and easy sampling source of biological information, since it transports a large variety of molecules including DNA, coding and non-coding regulatory RNA, proteins and metabolites from all over the body. Their dynamics reflects homeostatic regulation [ 1 – 3 ], physiological changes [ 4 , 5 ] and variations in immune capacity [ 6 , 7 ]. Circulating molecules also provide valuable insights into complex phenotypes such as obesity and diabetes [ 8 , 9 ], health status [ 10 ], sensitivity to heat stress [ 11 ] and nutrient efficiency for productive outputs [ 3 , 7 , 12 ].…”

“…Therefore, there is a need to find molecular biomarkers that accurately differentiate high and low FE animals and that can be further used for improving FE of growing animals in breeding programs or nutritional decision tools. So far, various studies have revealed differences in the whole blood transcriptome between low RFI (most feed efficient) and high RFI pigs (less feed efficient) at post-weaning [ 12 ] and during the growing period [ 3 , 7 ]. Moreover, the concentration of IGF-1 in blood plasma of juvenile post-weaned pigs was correlated with RFI measured during the growing period [ 17 ], suggesting that circulating molecules may even serve as early indicators for FE.…”

Analysis of Merged Whole Blood Transcriptomic Datasets to Identify Circulating Molecular Biomarkers of Feed Efficiency in Growing Pigs

“…Peripheral blood is widely used in human medicine and veterinary elds as a relevant and easy sampling source of biological information, since it transports a large variety of molecules including genes, transcripts, proteins, metabolites and non-coding regulatory RNA from all over the body. Their dynamics re ects homeostatic regulation [1][2][3], physiological changes [4,5] and variations in immune capacity [6,7]. Circulating molecules also provide valuable insights into complex phenotypes such as obesity and diabetes [8,9], health status [10], sensitivity to heat stress [11] and nutrient e ciency for productive outputs [3,7,12].…”

“…Therefore, there are huge expectations to nd predictive molecular biomarkers for incorporating FE in breeding programs or nutritional decision tools. So far, various studies have revealed differences in the whole blood transcriptome between low RFI (most feed e cient) and high RFI pigs (less feed e cient) at post-weaning [12] and during the growing period [3,7]. Moreover, the concentration of IGF-1 in blood plasma of juvenile post-weaned pigs was correlated with RFI measured during the growing period [17], which suggests that circulating molecules may even serve as early indicators for FE.…”