Antioxidant, anti-inflammatory, and immunomodulatory pathways of Citrus limon juice in a respiratory-irritated rat model.

Introduction Respiratory injuries with immunosuppression represent a challenge worldwide. This work aimed to clarify the efficacy of Hesawi Citrus limon juice (lemon juice, LJ) in ameliorating respiratory irritation in a model rat induced by surgical intratracheal instillation of glycolic acid. Methods Rats were assigned to five groups. Groups (1 and 2): normal and negative control, respectively; Group (3): positive model group; Groups (4 and 5): treated groups that received 3 and 6 mL/kg/day LJ orally, respectively. At 3 weeks of the experiment, groups 2, 3, 4, and 5 underwent surgical intratracheal instillation with 0.2 mL/kg body weight saline for group 2 and 0.2 mL/kg body weight 5 % glycolic acid for groups 3, 4, and 5. Results The model group exhibited inflammatory signs, evidenced by a significant increase in the total leucocyte count ( P < 0.01), neutrophils % ( P < 0.05), inflammatory cytokines (TNF-α, IL-6), and C-reactive protein (CRP), accompanied by a decrease in lymphocytes % and an increase in neutrophils/lymphocyte ratio. Likewise, model rats exhibited significant adverse alterations ( P < 0.05) in the phagocytic index and in glucose consumption with lymphocytes stimulated with either lipopolysaccharide or phytohemagglutinin-P. The high dose of LJ significantly ( P < 0.05) mitigated the inflammatory signs to a greater extent than the low dose. Lung tissue glutathione peroxidase, superoxide dismutase, and catalase activities were reduced in model rats, whereas a high LJ dose significantly elevated them ( P < 0.05). A high dose of LJ supplementation normalized TNF-α, IL-6, and CRP levels. Discussion Consistent with the other data, histological examination of the lung and trachea showed only slight or no inflammatory lesions, with the effect most pronounced at the high dose. In conclusion, the bioactive constituents of LJ control oxidative stress and inflammation, enhance immune function, and, in a dose-dependent manner, ameliorate lung tissue irritation induced by surgical intratracheal instillation of glycolic acid.