Effects of immunological challenge induced by lipopolysaccharide on skeletal muscle fiber type conversion of piglets1

Abstract

The objective of this study was to investigate the effects of immunological challenge on the skeletal muscle fiber type conversion of piglets. Sixteen Large White weaned barrows (28 ± 3 d, 8.22 ± 0.89 kg BW) were allotted by weight and litter to 2 groups: the control group and the lipopolysaccharide (LPS) group. Saline (control) or LPS was injected intravenously via a jugular catheter on d 1, 3, 5, 7, 9, 11, 13, and 15 at an initial dosage of 80 μg/kg BW, which was increased by 30% at each subsequent injection. Blood samples were collected via the jugular catheter 3 h after the LPS challenge on d -1, 1, 5, 9, and 13. Muscle tissue samples were collected from the LM after exsanguination on d 15. The LPS challenge increased the plasma IL-6, tumor necrosis factor-α (TNF-α), cortisol, IL-1β, and haptoglobin concentrations on d 1 and 5 ( < 0.01) and increased the plasma IL-6 ( < 0.05), TNF-α ( < 0.05), and haptoglobin ( < 0.01) levels on d 9. Compared with that of the control group, the ADG of the LPS group decreased by 40.00% ( < 0.01), 29.52% ( < 0.05), and 19.30% ( < 0.05), and the ADFI decreased by 25.09% ( < 0.01), 23.15% ( < 0.05), and 19.47% ( < 0.05) during d 1 to 4, d 5 to 8, and d 9 to 15, respectively. In the LM of LPS-challenged piglets, myosin heavy chain 1 (MyHC1) mRNA and protein expression tended to be reduced ( = 0.08, 0.09), whereas mRNA, mRNA, and MyHC2 protein expression increased ( < 0.05). The LPS challenge reduced succinic dehydrogenase (SDH) activity ( < 0.05) and increased lactate dehydrogenase (LDH) activity ( < 0.05) in the LM of piglets. Compared with those in the control group, transcriptional peroxisome proliferator-activated receptor coactivator-α () mRNA ( < 0.05), calcineurin (CaN) mRNA, and protein expression were reduced ( < 0.05), and PGC-α protein expression tended to be reduced ( = 0.08) in the LM of LPS-challenged piglets. These results show that immunological challenge induced by LPS resulted in a shift from type I to type II fibers in the LM of piglets, which may be mediated by the downregulation of the CaN/PGC-α signaling pathway.

Probing the molecular regulation of lipopolysaccharide stress in piglet liver by comparative proteomics analysis

“…In our previous study, LPS challenged piglets were found with increased plasma pro‐inflammatory cytokines (IL‐6 and IL‐1β) concentration ( P <0.05) on day 1, 5 and 9. But on day 13, no significant difference in concentration of pro‐inflammatory cytokines was observed between control and LPS treatment group samples . However, to our surprise, our SWATH analysis showed that even on day 15, there is a significant difference in abundance of differentially expressed proteins that were closely related to the expression of common inflammatory mediators, such as IL‐6, IL‐1β and TNF‐α (detailed in Table ).…”

“…Our laboratory has a long‐standing research interest in understanding molecular mechanisms of LPS‐induced immunological stress using weaned piglets as a model. Previously we have examined LPS‐induced inflammation along with the high levels of plasma IL‐1β, IL‐6 and TNF‐α in the initial stages of the experiment . However, the levels of inflammatory cytokines to LPS challenge were attenuated during subsequent injections after 13 days .…”

“…Previously we have examined LPS‐induced inflammation along with the high levels of plasma IL‐1β, IL‐6 and TNF‐α in the initial stages of the experiment . However, the levels of inflammatory cytokines to LPS challenge were attenuated during subsequent injections after 13 days . This observation inspired us to explore the cellular mechanisms for molecular regulation of LPS stress and its associated immunological stress resistance formed in piglets.…”

“…In our previous study, we have employed the piglets as a model of immunological stress for 15 days. The results demonstrated that the level of plasma IL‐6 and TNF‐α in LPS challenge piglets was increased after treatment for 9 days, while the levels of plasma inflammatory cytokines upon LPS challenge were surprisingly attenuated on day 13 . However, little is known for the molecular regulation of LPS with relatively long period of stress in piglet.…”

Fetal betaine exposure modulates hypothalamic expression of cholesterol metabolic genes in offspring cockerels with modification of promoter DNA methylation

“…In addition, we elucidated that first effect of lower cholesterol content in the hypothalamus was related to the lower body weight, which was in agreement with recent finding that an increase level of methyl donor during prenatal stage significantly downregulated the body weight of offspring in female rat ( Giudicelli et al., 2013 ). Other studies documented that methyl donor supplementation increased of fetus weight in rat ( Oster et al., 2016 ) and birth weight in swine ( Jia et al., 2015 ), because low maternal methyl donor associated with the decreased birth weight. Negative transgenerational effects about glucose metabolism in F1 and F2 offspring were reported in reduction of protein's diet model ( Pinheiro et al., 2008 ).…”