3,4,5-Trihydroxycinnamic acid exerts anti-asthmatic effects in vitro and in vivo.

3,4,5-Trihydroxycinnamic acid (THCA) has been reported to possess anti-inflammatory activity. However, the effect of THCA for treating allergic asthma was unknown. Therefore, in the present study, the anti-asthmatic effects of THCA were studied in both in vitro and in vivo studies. In phorbol 12-myristate 13-acetate (PMA)-stimulated A549 airway epithelial cells, THCA pretreatment decreased the mRNA expression and secretion of interleukin (IL)-8, monocyte chemoattractant protein-1 (MCP-1), and intercellular adhesion molecules 1 (ICAM-1), and reduced the mRNA expression of matrix metalloproteinase 9 (MMP-9). THCA also inhibited PMA-induced protein kinase B (AKT), mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) activation in A549 cells. In lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages, THCA pretreatment suppressed the mRNA expression of ICAM-1 and MMP-9. In addition, THCA suppressed the adhesion of EOL and A549 cells. In ovalbumin (OVA)-administered asthmatic mice, THCA exerted inhibitory activity on IL-5, IL-13, and MCP-1 in bronchoalveolar lavage fluid (BALF) and on OVA-specific immunoglobulin E (IgE) in serum. THCA attenuated the numbers of inflammatory cells in BALF and the influx of inflammatory cell in lung tissues. Furthermore, THCA downregulated the levels of inducible nitric oxide (iNOS), cyclooxygenase-2 (COX-2), and leukotriene B4 (LTB4) expression, mucus production and CREB phosphorylation as well as Penh value. These effects were accompanied by suppression of AKT, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and NF-κB activation. Therefore, the results of the current study suggest that THCA may be a valuable adjuvant or therapeutic in the prevention or treatment of allergic asthma.