Abstract: This experiment aimed to study the effects of fine particulate matter (PM_2.5) from pig house on the arginine metabolism, expression of inflammatory cytokines and macrophage polarization markers in primary porcine alveolar macrophages (PAMs). Bronchoalveolar lavage was conducted to isolate PAMs. After PAMs were purified, Diff-quik staining were used to identify PAMs and F4/80 labeling were used to identity PAMs, and cell viability of PAMs was determined. The PAMs were further divided into the control and the PM_2.5 (50 μg·mL^-1) groups, continuing cultured for 4, 8, or 12 h to determine cell viability, the cellular supernatant was collected to detect the concentration of nitric oxide (NO), PAMs were lysed to detect the activity of arginase, and RT-PCR was used to detect the relative expression of cytokines IL-1β, TNF-α and IL-10, and the relative expression of M1 and M2 markers CD80 and CD206 in PAMs. The results showed that PAMs were successfully isolated by bronchoalveolar lavage and purified, the cell viability of PAMs gradually decreased when the culture time was increased (P<0.05). After PM_2.5 treatment, the concentration of NO in the cellular supernatant was significantly increased (P<0.05) and the activity of arginase significantly decreased (P<0.01). The mRNA expression of inflammatory cytokines IL-1β and TNF-α were significantly increased (P<0.01), and the mRNA expression of IL-10 was decreased (P<0.05). In the early stage of PM_2.5 treatment, the mRNA expression of CD80 was significantly increased (P<0.01), and the mRNA expression level of CD206 was significantly decreased in the later stage (P<0.01). These results suggested that PM_2.5 from pig house promotes PAMs to the M1 polarization and promotes the development of inflammation.

Key words: fine particulate matter, porcine alveolar macrophages, macrophage polarization