Inhalation of nebulized omega-3 fatty acids mitigate LPS-induced acute lung inflammation in rats: Implications for treatment of COPD and COVID-19

Abstract

Many current treatment options for lung inflammation and thrombosis come with unwanted side effects. The natural omega-3 fatty acids (O3FA) are generally anti-inflammatory and antithrombotic. O3FA are always administered orally and occasionally by intravenous (IV) infusion. The main goal of this study is to determine if O3FA administered by inhalation of a nebulized formulation mitigates LPS-induced acute lung inflammation in male Wistar rats. Inflammation was triggered by intraperitoneal injection of LPS once a day for 14 days. One hour post-injection, rats received nebulized treatments consisting of egg lecithin emulsified O3, Budesonide and Montelukast, and blends of O3 and Melatonin or Montelukast or Cannabidiol; O3 was in the form of free fatty acids for all groups except one group with ethyl esters. Lung histology and cytokines were determined in n = 3 rats per group at day 8 and day 15. All groups had alveolar histiocytosis severity scores half or less than that of the disease control (Cd) treated with LPS and saline only inhalation. IL-6, TNF-α, TGF-β, and IL-10 were attenuated in all O3FA groups. IL-1β was attenuated in most but not all O3 groups. O3 administered as ethyl ester was overall most effective in mitigating LPS effects. No evidence of lipid pneumonia or other chronic distress was observed. These preclinical data suggest that O3FA formulations should be further investigated as treatments in lung inflammation and thrombosis related lung disorders, including asthma, chronic obstructive pulmonary disease, lung cancer and acute respiratory distress such as COVID-19.

Keywords: Budesonide; Cannabidiol; Docosahexaenoic acid (DHA); Docosapentaenoic acid (DPA); Eicosapentaenoic acid (EPA); Montelukast; Omega-3 fatty acids.

Fig. 1

Represents alveolar histiocytosis severity scores. All animals in the control disease (Cd) group had the highest severity score (0.61). Reduced alveolar histiocytosis scores are seen in all the treatment groups. B-ref group had the lowest score compared to all treatment groups. The O3 treatment group means scored less than half severity compared to Cd. Inferential statistics were not calculated for these visual data. Images and diagnoses for all animals are presented in Supplementary Fig. 1.

Fig. 2

Cytokine levels in treatments compared to the disease control Cd (mean ± SD). No time effects were found for these groups; day 8 and day 15 results were pooled to yield n = 6. A) IL-6 levels are downregulated and reached statistical significance in all the treatment groups and B-Ref by pairwise comparison to disease control Cd (*p < 0.05). B) TNF-α levels are downregulated and reached statistical significance in all the treatment groups and B-Ref (*p < 0.05), except EPL. All statistically significant treatment groups have vertical lines, except EPL C) TGF-β levels are downregulated; all significantly different from Cd (*p < 0.05), except EPL and O3-0.5 groups. All statistically significant treatment groups have vertical lines, except EPL and O3-0.5.

Fig. 3

Cytokine levels in treatments compared to the disease control Cd (mean ± SD). Time effects were significant for these groups; day 8 results were compared to day 8, and day 15 to day 15, n = 3 per group. A) With time IL-10 for O3-0.5, CannO3, and B-ref increased, whereas O3EE decreased (*p < 0.05 for time effect). All comparisons at single time points are significant except EPL at both time points, O3-0.5 at day 15 and MontO3 at day 8 (not significant “ns”). B) IL-1β levels were mostly not significantly different from Cd except those labeled with ¶. O3EE is the only treatment significant at both the time points. O3, B-Ref, MelO3 and CannO3 are significant only at the 15 day time point.