Exposure to Particulate Matter in the Broiler House Causes Dyslipidemia and Exacerbates It by Damaging Lung Tissue in Broilers

Abstract

The high concentration of particulate matter (PM) in broiler houses seriously endangers the biological safety of broilers and causes low growth performance, deserving more attention. This study aimed to investigate the effects of PM collected from a broiler house on the lung and systemic inflammatory responses and liver lipid anabolic process in broilers. Broilers were systemically exposed to fresh air (control) and 4 mg·m^-3 and 8 mg·m^-3 total suspended particles (TSP). Lung, liver, and serum were sampled after 7 (E7) and 14 (E14) days of PM exposure and 7 days after self-recovery (R 7). Corresponding kits were used to assay the inflammatory cytokines and serum biochemical indicators. The expression levels of genes related to lipid metabolism were detected by real-time polymerase chain reaction (RT-PCR) assay. The results showed a significant decrease in the average daily gain in broilers for 7 days of PM exposure (p < 0.05) and clear lung and liver inflammations in PM groups. In addition, upregulation of lung interleukin (IL)-1β and IL-8 and serum low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) occurred after 7 days of PM exposure (p < 0.05), and upregulation of lung serum tumor necrosis factor (TNF)-α and cholesterol (CHOL) occurred after 14 days of PM exposure (p < 0.05). A decrease in serum total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-px) levels was found after 14 days of PM exposure (p < 0.05), and the GSH-px level was maintained until 7 days after cessation of exposure (p < 0.05). Seven days after cessation of exposure, the expression levels of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (Hmgcs2) and fatty acid synthase (Fas) genes significantly increased (p < 0.05) and decreased (p < 0.05), respectively. These results demonstrate that exposure to PM in broiler houses can induce systemic inflammation and dyslipidemia through local pulmonary inflammation and also exert toxic effects on the liver by disturbing the expression of genes involved in the hepatic lipid anabolic process.

Keywords: broiler house; dyslipidemia; inflammatory response; lung injury; particulate matter.

Figure 1

Effects of particulate matter exposure on lung histomorphology of broilers. Hematoxylin and eosin (H&E) staining of the lung. (A,D,G) represent the control group after E7, E14, and R7, respectively; (B,E,H) represent the exposure group at PM concentration of 4 mg·m⁻³ after E7, E14, and R7, respectively; (C,F,I) represent the exposure group at PM concentration of 8 mg·m⁻³ after E7, E14, and R7, respectively. The stubby arrows show hemorrhaging in the lungs and bronchi filled with blood cells. The elongated arrows indicate pulmonary capillary shrinkage collapse and deformation. E7, exposure for 7 days; E14, exposure for 14 days; R7, recovery for 7 days.

Figure 2

Effects of particulate matter exposure on liver histomorphology of broilers. Hematoxylin and eosin (H&E) staining of the liver. (A,D,G) represent the control group after E7, E14, and R7, respectively; (B,E,H) represent the exposure group at PM concentration of 4 mg·m⁻³ after E7, E14, and R7, respectively; (C,F,I) represent the exposure group at PM concentration of 8 mg·m⁻³ after E7, E14, and R7, respectively. Arrows indicate inflammatory cell infiltration. E7, exposure for 7 days; E14, exposure for 14 days; R7, recovery for 7 days.

Figure 3

Effects of particulate matter exposure on inflammatory factor levels in lung of broilers. (A–E) represent the TNF-α, IL-1β, IL-6, IL-8, and IL-10 levels in lung tissue of broilers after E7, E14, and R7, respectively. Data are presented as mean ± SEM of groups (n = 8). Different letters indicate statistically significant differences between groups (p < 0.05). E7, exposure for 7 days; E14, exposure for 14 days; R7, recovery for 7 days.

Figure 4

Effects of particulate matter exposure on inflammatory factor levels in serum of broilers. (A–E) represent the TNF-α, IL-1β, IL-6, IL-8, and IL-10 levels in serum of broilers after E7, E14, and R7, respectively. Data are presented as mean ± SEM of groups (n = 8). Different letters indicate statistically significant differences between groups (p < 0.05). E7, exposure for 7 days; E14, exposure for 14 days; R7, recovery for 7 days.

Figure 5

Effects of particulate matter exposure on the antioxidant enzyme content in serum of broilers. (A–D) represent the T-AOC, T-SOD, CAT, and GSH-px content in serum of broilers after E7, E14, and R7, respectively. Data are presented as mean ± SEM of groups (n = 8). Different letters indicate statistically significant differences between groups (p < 0.05). E7, exposure for 7 days; E14, exposure for 14 days; R7, recovery for 7 days.

Figure 6

Effects of particulate matter exposure on serum biochemical indices related to liver function of broilers. (A–E) represent the albumin, AKP, ALT, AST, and T-BIL levels in serum of broilers after E7, E14, and R7, respectively. Data are presented as mean ± SEM of groups (n = 8). Different letters indicate statistically significant differences between groups (p < 0.05). E7, exposure for 7 days; E14, exposure for 14 days; R7, recovery for 7 days.

Figure 7

Effects of particulate matter exposure on lipid concentration in serum of broilers. (A–E) represent the TP, LDL-C, GLU, CHOL, and TG levels in serum of broilers after E7, E14, and R7, respectively. Data are presented as mean ± SEM of groups (n = 8). Different letters indicate statistically significant differences between groups (p < 0.05). E7, exposure for 7 days; E14, exposure for 14 days; R7, recovery for 7 days.

Figure 8

Effects of particulate matter exposure on relative mRNA expression levels of genes related to lipid metabolism in the liver of broilers. (A–D) represent the Fas, Hmgcr, Hmgcs2, and PPARα levels in serum of broilers after E7, E14, and R7, respectively. Data are presented as mean ± SEM of groups (n = 8). * p < 0.05. E7, exposure for 7 days; E14, exposure for 14 days; R7, recovery for 7 days.