EBTr (NBL-4)

Invasion Rates of Four Mycoplasma Strains into EBL, MDBK, BT and EBTr Cells

Mycoplasma bovis (M. bovis) is an emerging and economically important pathogen in the cattle industry. It is responsible for a variety of diseases such as pneumonia, arthritis, and mastitis in cattle. M. bovis can invade non-phagocytic cells, which is important for immune evasion and dissemination in the host. Li's team investigated the invasion mechanism of M. bovis into four types of non-phagocytic cells and quantify the invasion rates of different strains.

The invasion rates of the three strains of M. bovis (PG45, 07801, 08M) was determined by the plate counting method. The invasion rate of PG45, 08M, and 07801 into EBTr cells was the highest among all cells (EBL, MDBK, BT), and the BT cells was the lowest. The invasion efficiency of EBTr was significantly higher than that of MDBK cells, while it was not significantly higher than that of EBL cells (Fig. 1A–D). PG45 and PG45-GFP showed identical invasion rates across all cell types as GFP addition did not influence the invasion rate (Fig. 1A and D). PG45, 08M, and 07801 could all invade multiple non-phagocytic cells, with 07801 having a slightly weaker ability to invade cells than PG45 and 08M.

Protective Effects of N-Acetylcysteine on Lipopolysaccharide-Induced Respiratory Inflammation and Oxidative Stress

Lipopolysaccharide (LPS) is the main component of the cell wall of gram-negative bacteria and a strong inducer of inflammation and oxidative stress. N-acetylcysteine (NAC) is an acetylated derivative of L-cysteine that reportedly has anti-inflammatory and antioxidant properties. Chen's group examined the protective effects and the underlying mechanisms of NAC on LPS-induced respiratory inflammation and oxidative stress in bovine embryo tracheal cells (EBTr) and mouse models of acute lung injury (ALI).

EBTr cell viability was inhibited by 16 μg/mL LPS but not by 0–8 μg/mL LPS (Fig. 2A), showing that LPS at concentrations lower than 8 μg/mL had no effect and could be used for further study. Cell viability was also inhibited by 5 mM NAC (Fig. 2B), but not by 0–1 mM NAC. These results show that the selected concentrations of LPS and NAC do not affect EBTr viability. IL-6 and IL-8 secretion peaked at 6 h of LPS treatment (Fig. 3). Expression of IL-6 and IL-8 also peaked at 6 h. HO-1, Nrf2, and NQO1 mRNA levels also changed significantly at 6 h of LPS treatment. These results demonstrate that 6 h is an appropriate incubation period to induce oxidative stress and inflammation. Pretreatment with 1 mM NAC rescued changes in HO-1, Nrf2, and NQO1 mRNA levels and downregulated LPS-induced IL-6 and IL-8 expression and secretion after 6 h.