Therapeutic effects of minocycline on oleic acid-induced acute respiratory distress syndrome (ARDS) in rats

Abstract

Acute respiratory distress syndrome (ARDS) is a serious intensive care condition. Despite advances in treatment over the previous few decades, ARDS patients still have high fatality rates. Thus, more research is needed to improve the outcomes for people with ARDS. Minocycline is an antibiotic with antioxidant, anti-inflammatory, and anti-apoptotic effects. In the current investigation, the therapeutic effects of minocycline on oleic acid-induced ARDS were evaluated. Male rats were classified into 6 groups, 1. control (normal saline), 2. oleic acid (100 µL, i.v.), 3-5. oleic acid + minocycline (50, 100, 200 mg/kg, i.p.), and 6. minocycline (200 mg/kg, i.p.) alone. Twenty-four hours after the oleic acid injection, the lung tissue is isolated, weighed, and the middle part of the right lung is immediately placed in the freezer, while the middle part of the left lung is placed in formalin and sent to the laboratory for pathology testing. Then, the amounts of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), cytokines (interleukin-1 beta (IL-1β), tumor necrosis factor-α (TNF-α)), B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X (Bax), and cleaved caspase-3 were determined in lung tissue. Administration of oleic acid increased emphysema, inflammation, vascular congestion, hemorrhage, MDA amount, Bax/Bcl-2 ratio, cleaved caspase-3, IL-1β, TNF-α levels, and decreased GSH, SOD, and CAT levels in comparison with the control group. The administration of minocycline could significantly reduce pathological and biochemical alterations induced by oleic acid. Minocycline has a therapeutic effect on oleic acid-induced ARDS through antioxidant, anti-inflammatory, and anti-apoptotic properties.

Keywords: Anti-bacterial agents; Anti-inflammatory agents; Antioxidants; Apoptosis; Cytokines; Respiratory system.

Fig. 1

Effect of minocycline on oleic acid-induced histopathological alterations in the lung tissue (H&E staining × 200). A Control group, B OA (100 mg/kg), C OA + Mino (50 mg/kg), D OA + Mino (100 mg/kg), E OA + Mino (200 mg/kg), F Mino (200 mg/kg). OA, oleic acid; Mino, minocycline

Fig. 2

Effect of minocycline on oleic acid-induced A lipid peroxidation and B GSH level in lung tissue. The data is provided as a mean ± SD (n = 6). An analysis of variance (ANOVA) was used, followed by a post hoc analysis. For statistical analysis, Tukey’s test was utilized. ###P < 0.001, #P < 0.05 when compared with the control group, ***P < 0.001, **P < 0.01, and *P < 0.05 when compared to oleic acid group. GSH, glutathione; MDA, malondialdehyde; Mino, minocycline; OA, oleic acid

Fig. 3

Effect of minocycline on oleic acid-induced A SOD and B CAT levels in lung tissue. The data is provided as a mean ± SD (n = 6). An analysis of variance (ANOVA) was used, followed by a post hoc analysis. For statistical analysis, Tukey’s test was utilized. ###P < 0.001 when compared to the control group, ***P < 0.001, **P < 0.01, and *P < 0.05 when compared with the oleic acid group. CAT, catalase; Mino, minocycline; OA, oleic acid; SOD, superoxide dismutase

Fig. 4

Effect of oleic acid and minocycline on the IL-1β and TNF-α levels in the lung tissue. A Specific bands for IL-1β and TNF-α levels have been investigated using Western blot. B IL-1β level data by densitometric analysis. C TNF-α level data by densitometric analysis. The data is mean ± SD (n = 5). ANOVA and posttest Tukey–Kramer were used for statistical analysis. ###P < 0.001 compared with the control group, and ***P < 0.001 and **P < 0.01 compared with the oleic acid group. Mino, minocycline; OA, oleic acid

Fig. 5

Effect of oleic acid and minocycline on the Bax/Bcl-2 ratio and cleaved caspase-3 level in the lung tissue. A Specific bands for Bax/Bcl2 ratio and cleaved caspase-3 level have been investigated using Western blot. B Bax/Bcl-2 ratio data by densitometric analysis. C Cleaved caspase-3 level data by densitometric analysis. The data is mean ± SD (n = 5). ANOVA and posttest Tukey–Kramer were used for statistical analysis. ###P < 0.001, ##P < 0.01 compared with the control group, and *P < 0.05 compared with the oleic acid group. Mino, minocycline; OA, oleic acid