Effects of membrane-type PBLs on the expression of TNF-α and IL-2 in pulmonary tissue of SD rats after LPS-induced acute lung injury

Background. As the first target organ, the lungs usually display symptoms of acute lung injury (ALI). Pro-inflammatory cytokines, such as tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-2, are crucial in triggering the systemic inflammatory response syndrome and the subsequent cascading effects. Therefore, the inhibition of the release of inflammatory mediators has become an important strategy for the prevention and treatment of ALI. Objectives. To evaluate the preventive and therapeutic effects of transmembrane peripheral blood leukocytes (PBLs) on lipopolysaccharide (LPS)-induced ALI and its mechanism. Materials and methods. Sixty Sprague Dawley rats were randomly divided into experimental and control groups. The animal model was established through intravenous injection of LPS. Plasmid PBLs were dissolved in a saline solution and injected into the experimental group of rats in different doses (0.1 mg, 0.2 mg and 0.3 mg per rat) using the in situ injection method. After injecting the PBL solution, the rats were killed after 12 h, 24 h, 36 h, or 48 h. The expression of microRNA (miRNA)-25 and miRNA-223 was detected using the semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). Tumor necrosis factor alpha and IL-2 levels in bronchoalveolar lavage fluid (BALF) were detected with an enzyme-linked immunosorbent assay (ELISA). The expressions of TNF-alpha and IL-2 proteins in lung tissue were detected using western blotting. Results. The expression of miRNA-25 was upregulated in tissues and BALF in a dose- and time-dependent manner, while miRNA-223 was downregulated. The differences were statistically significant compared to the control group (p < 0.05). The TNF-alpha and IL-2 levels in the BALF of rats in the experimental group were increased in a dose-dependent manner compared to the control group (p < 0.05). In the presence of PBLs, the expressions of TNF-alpha, IL-2, miRNA, and proteins were inhibited. Thus, PBLs were found to alleviate pulmonary tissue damage. Conclusions. In summary, PBLs have a protective effect on rats with ALI through the downregulation of TNF-alpha and IL-2 expression.