Insulin-like growth factor-1 expression levels in pro-inflammatory response in calves with neonatal systemic inflammatory response syndrome

The objective of this study was to investigate the mRNA expression of insulin-like growth factor-1 (IGF-1), pro-inflammatory cytokines (IL-1β, IL-6, IL-18, and TNF-α), serum immunoglobulin profiles (IgG and IgM), and lipid peroxidation status (MDA) in relation to pro-inflammatory cytokines. A case-controlled, prospective, and observational investigation was completed on 85 calves. Total RNA was isolated from whole blood samples of both the SIRS and healthy calves, followed by reverse transcription into cDNA. The resulting cDNAs were mixed with iTaq Universal SYBR Green Supermix and primers specific to the relevant genes using the Rotor-Gene Q instrument. After the reaction was completed, gene expressions were normalised against β-actin using the 2^-ΔΔCT method. The mRNA levels of pro-inflammatory cytokines namely (IL-1β [SIRS: 2.15 ± 0.55, Control: 1.13 ± 0.62; P = 0.001], IL-6 [SIRS: 2.82 ± 0.52, Control: 0.91 ± 0.11; P < 0.001], IL-18 [SIRS: 1.92 ± 0.41, Control: 0.99 ± 0.13; P < 0.001], and TNF-α [SIRS: 2.59 ± 0.28, Control: 0.93 ± 0.09; P < 0.001]) and IGF-1 (SIRS: 3.55 ± 0.55, Control: 0.91 ± 0.15; P < 0.001) were up-regulated in calves with SIRS, while serum IgG (SIRS: 4.16 ± 0.26, Control: 1.73 ± 0.17; P < 0.001), IgM (SIRS: 1.55 ± 0.11, Control: 1.09 ± 0.13; P < 0.001), and MDA levels (SIRS: 41.12 ± 3.48, Control: 3.76 ± 0.81; P < 0.001) increased significantly in these calves. Furthermore, significant (P < 0.01) positive correlations were found in calves with SIRS in relation to the expression levels of IL-1β, IL-6, IL-18, TNF-α, IGF-1, serum immunoglobulins, and MDA levels. These results suggest that IGF-1 could be a valuable pro-inflammatory marker, considering its high positive correlation with the expression levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-18, and TNF-α) and markers (MDA, IgG, and IgM) in calves with SIRS.