Dexmedetomidine mitigates lipopolysaccharide-induced acute lung injury in septic rats via inhibition of NF-κB associated anti-inflammatory pathway

Purpose: To investigate the effect of dexmedetomidine in a rat model of acute lung injury (ALI), and the underlying mechanism. Methods: Acute lung injury (ALI) was induced in adult male Sprague Dawley rats (n = 27) using lipopolysaccharide (LPS). Three rat groups were used (9 rats/group): untreated control, LPS and treatment groups. Pathological lesions in rat pulmonary tissues were assessed and inflammatory scores determined. The levels TNF-α and IL-6 in BALF were determined using their respective enzyme-linked immunosorbent assay (ELISA) kits, while protein levels of p-IκB and NF-κB p65 were assessed by Western blotting. Results: Lung tissue damage was markedly mitigated in treatment mice, relative to LPS mice (p < 0.05). Inflammatory scores and population of neutrophils and macrophages increased significantly in LPS mice, relative to control, but decreased by dexmedetomidine exposure (p < 0.05). Similarly, TNF-α and IL-6 levels in pulmonary tissue homogenates of LPS rats were increased, relative to control rats, but were downregulated by dexmedetomidine exposure (p < 0.05). Moreover, dexmedetomidine downregulated the expressions of p-IκB and NF-κB p65 in pulmonary tissues (p < 0.05). Conclusion: Dexmedetomidine mitigates LPS-induced ALI in rats by blocking the activation of NF-κB and IκB, coupled with inhibition of the secretion of TNF-α and IL-6. Keywords: Acute lung injury, Dexmedetomidine, Inflammatory cytokines, NF-κB pathway, Sepsis