Chinese herbal medicine plays an important role in regulating the nutritional metabolism of poultry and maintaining or improving normal physiological functions and animal health. The present study investigated the effects of dietary supplementation with Qiling Jiaogulan Powder (QLJP) on pulmonary fibrosis and pulmonary arteriole remodeling in low temperature-exposed broilers. Seven-day-old Ross 308 broilers (n = 240) were reared adaptively to 14 days of age. The broilers were randomly divided into six groups: A control group (basal diet and normal feeding temperature); model group (basal diet); low-, medium- and high-dose QLJP groups (basal diet supplemented with 1 g/kg, 2 g/kg, 4 g/kg QLJP); and L-Arg group (basal diet supplemented with 10 g/kg L-arginine). Additionally, all the broilers, except the broilers in the control group, from the age of 14 days old, had a house temperature continuously lowered by 2 °C each day until it reached 12 °C at 21 days of age, and the low temperature was maintained until the end of the experiment. There were four replicates per group and 10 birds per replicate. The results showed that the structure of the lung tissue was clearer and basically intact in the broilers in the QLJP groups, with a small number of collagen fibers formed, and the content of hydroxyproline (HYP) was significantly reduced. QLJP improved pulmonary arteriole lesions, such as tunica media thickening, intimal hyperplasia, arterial wall hypertrophy, and lumen narrowing. QLJP reduced the relative media thickness (%) and relative medial area (%) of the pulmonary arteriole, and significantly decreased the expression level of the alpha-smooth muscle actin (α-SMA) protein in pulmonary arteriole, which alleviated pulmonary arteriole remodeling. The quantitative real-time PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA) results showed that QLJP treatment significantly reduced the gene and protein levels of transforming growth factor-beta l (TGF-β1) and Smad2 in the lung and downregulated the gene and protein levels of collagen type I alpha 1 (COL1A1) and matrix metalloproteinase 2 (MMP2). In conclusion, the results of our study suggested that dietary supplementation with QLJP improved pulmonary fibrosis and pulmonary arteriole remodeling by inhibiting the expression of genes related to the TGF-β1/Smad2 signaling pathway and inhibited the occurrence and development of pulmonary arterial hypertension in low-temperature-exposed broilers.

The heart serves as the center of blood circulation, transporting oxygen and nutrients to all tissues and organs of the body. Cardiac function is closely associated with the growth performance, immune function, and meat quality of broilers. In this study, a broiler heat stress (HS) model was established by artificially controlling environmental temperature, and transcriptomic analysis was used to investigate the effect and underlying mechanisms of Qiling Jiaogulan Powder (QLJP) on heat stress-induced heart injury in broilers. The results showed that compared with the HS group, both the HS+QLJP and the QLJP groups exhibited significantly reduced the concentrations of myocardial injury indicators natriuretic peptide (ANP), brain natriuretic peptide (BNP), and cardiac Troponin I (cTn-I), and significantly increased the adenosine triphosphate (ATP) levels. Transcriptomic analysis of 42-day-old broiler hearts identified 218 differentially expressed genes (DEGs) between the HS+QLJP and the HS groups (181 upregulated and 37 downregulated genes), with KEGG enrichment in Cell cycle, ECM-receptor interaction, PI3K-Akt signaling pathway, and p53 signaling pathway. qPCR validation confirmed that compared with the HS group, the HS+QLJP group significantly upregulated relative expression of RRM2, COMP, DCK, BRCA1, CDK1, THBS2 and BUB1, and significantly downregulated expression of HK2 and GADD45 in myocardial tissue, consistent with RNA-seq results, thus verifying the reliability of sequencing data. And QLJP regulated the PI3K-Akt and p53 signaling pathways at both transcriptional and post-translational levels: (1) mRNA level: both the HS+QLJP and QLJP groups significantly upregulated the relative expression of PI3K, Akt, and BCL2 and downregulated the expression of p53, BAX, and Caspase-3 in myocardial tissue; (2) protein level: both the HS+QLJP and QLJP groups significantly elevated the protein levels of phosphorylated (p)-PI3K (Y524), p-Akt (Ser473), and BCL2, while reducing the protein levels of p53, BAX, and active Caspase-3 (Cys163) compared with the HS group. In conclusion, QLJP alleviates HS-induced broiler myocardial injury by reducing injury markers, restoring ATP, and regulating the PI3K-Akt/p53 pathway at transcriptional and post-translational levels to inhibit apoptosis. Transcriptomic results further support that QLJP may exert its cardioprotective effects through crosstalk among multiple signaling pathways, providing new insights into its pharmacological mechanism and enriching understanding of the pharmacological effects of Qiling Jiaogulan Powder.