Docosahexaenoic Acid Derivative Prevents Inflammation and Hyperreactivity in Lung Implication of PKC-Potentiated Inhibitory Protein for Heterotrimeric Myosin Light Chain Phosphatase of 17 kD in Asthma

The effects of a newly synthesized docosahexaenoic acid (DHA) derivative, CRBM-0244, on lung inflammation and airway hyperresponsiveness were determined in an in vitro model of TNF-alpha-stimulated human bronchi and in an in vivo model of allergic asthma. Mechanical tension measurements revealed that CRBM-0244 prevented bronchial hyperresponsiveness in TNF-alpha-pretreated human bronchi. Moreover, treatment with CRBM-0244 resulted in a decrease in NF-kappa B activation and cyclooxygenase-2 (COX-2) overexpression triggered by TNF-alpha. The inhibition of peroxisome proliferator-activated receptor-gamma with GW9662 abolished the CRBM-0244 mediated anti-inflammatory effects. CRBM-0244 reduced the Ca2+ sensitivity of bronchial smooth muscle through a decrease in the phosphorylation and expression of the PKC-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17 kDa (CPI-17). Results also revealed an overexpression of CPI-17 protein in lung biopsies derived from patients with asthma. Furthermore, the presence of specialized enzymes such as 5-lipoxygenase and 15-lipoxygenase in the lung may convert CRBM-0244 into active mediators, leading to the resolution of inflammation. The in vivo anti-inflammatory properties of CRBM-0244 were also investigated in a guinea pig model of allergic asthma. After oral administration of CRBM-0244, airway leukocyte recruitment, airway mucus, ovalbumin-specific IgE, and proinflammatory markers such as TNF-alpha and COX-2 were markedly reduced. Hence, CRBM-0244 treatment prevents airway hyperresponsiveness, Ca2+ hypersensitivity, and the overexpression of CPI-17 in lung tissue. Together, these findings provide key evidence regarding the mode of action of CRBM-0244 in the lung, and point to new therapeutic strategies for modulating inflammation in patients with asthma.