Original Contribution ROSMARINIC ACID INHIBITS LUNG INJURY INDUCED BY DIESEL EXHAUST PARTICLES CHIAKI SANBONGI,* HIROHISA TAKANO, †‡ NAOMI OSAKABE,* NAOKO SASA,* MIDORI NATSUME,* RIE YANAGISAWA, † KEN-ICHIRO INOUE, ‡ YOJI KATO, § TOSHIHIKO OSAWA, ¶ and TOSHIKAZU YOSHIKAWA ‡ *Health and Bioscience Laboratories, Meiji Seika Kaisha, Ltd., Saitama, Japan; † Pathophysiology Research Team, National Institute for Environmental Studies, Ibaraki, Japan; ‡ First Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan; § School of Humanities for Environmental Policy and Technology, Himeji Institute of Technology, Hyogo, Japan; and ¶ Laboratories of Food and Biodynamics, Nagoya University Graduate School of Bioagricultural Sciences, Aichi, Japan (Received 8 August 2002; Accepted 17 January 2003) Abstract—Epidemiological and experimental studies have suggested that diesel exhaust particles (DEP) may be involved in recent increases in lung diseases. DEP has been shown to generate reactive oxygen species. Intratracheal instillation of DEP induces lung inflammation and edema in mice. Rosmarinic acid is a naturally occurring polyphenol with antioxidative and anti-inflammatory activities. We investigated the effects of rosmarinic acid on lung injury induced by intratracheal administration of DEP (500 g/body) in mice. Oral supplementation with administration of rosmarinic acid (2 mg/body for 3 d) inhibited DEP-induced lung injury, which was characterized by neutrophil sequestration and interstitial edema. DEP enhanced the lung expression of keratinocyte chemoattractant (KC), inter- leukin-1, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1, which was inhibited by treatment with rosmarinic acid. DEP enhanced expression of iNOS mRNA and formation of nitrotyrosine and 8-OHdG in the lung, which was also inhibited by rosmarinic acid. These results suggest that rosmarinic acid inhibits DEP-induced lung injury by the reduction of proinflammatory molecule expression. Antioxidative activities of rosmarinic acid may also contribute to its protective effects. © 2003 Elsevier Inc. Keywords—Diesel exhaust particles, Lung injury, Reactive oxygen species, Rosmarinic acid, Free radicals INTRODUCTION It is well-recognized that air pollution is causally linked to a variety of clinical disorders afflicting the lung [1]. Epidemiological studies have shown a positive relation- ship between exposure to ambient particulate matter (PM) and adverse respiratory health effects in humans [2,3]. Exposure to air pollutants generated by petrol- and diesel-burning engines aggravates the symptoms of re- spiratory diseases such as asthma and rhinitis [4,5]. Air pollutants expelled by diesel engine-powered automo- biles include diesel exhaust particles (DEP), which are known to be major constituents of atmospheric PM in metropolitan areas. DEP have been linked to lung cancer, bronchitis [6], edematous lung changes [7], and airway inflammation [8]. DEP enhances the manifestation of allergic asthma in a variety of murine models [9 –12]. Moreover, short-term exposure to DEP reportedly in- duces an acute inflammatory response in human as well as in animals [1,7]. DEP instilled intratracheally generates reactive oxy- gen species (ROS) in the lung of exposed mice [7,8,13,14]. It has been suggested that P450 reductase and/or P450 induction is involved in the process [14 – 16]. Furthermore, ROS are implicated in the pathogene- sis of lung injury caused by DEP, since superoxide dismutase prevents lung injury [14]. Thus, other strate- gies that block ROS should be useful for amelioration of DEP-induced lung injury. However, to date, an effective preventive approach has not yet been established for their adverse respiratory health effects. Rosmarinic acid, a natural phenolic substance (Fig. 1) contained in many Lamiaceae herbs such as Perilla fru- tescens, sage, basil, and mint, inhibits complement-de- pendent inflammatory processes [17,18] and may have therapeutic potential [19]. Rosmarinic acid in Perilla Address correspondence to: Dr. Chiaki Sanbongi, Meiji Seika Kai- sha, Ltd., Health and Bioscience Laboratories, 5-3-1 Chiyoda, Sakado, Saitama 350-0289, Japan; Tel: +81 492-84-7593; Fax: +81 492-84- 7598; E-Mail: chiaki_sambongi@meiji.co.jp. Free Radical Biology & Medicine, Vol. 34, No. 8, pp. 1060 –1069, 2003 Copyright © 2003 Elsevier Inc. Printed in the USA. All rights reserved 0891-5849/03/$–see front matter doi:10.1016/S0891-5849(03)00040-6 1060