IntroductionInterstitial pneumonia represents a heterogeneous group of idiopathic interstitial lung diseases that have a grave prognosis. It can be clinically classified as an acute and a chronic form (Bouros et al 1 ; Michaelson et al 2 ). Acute interstitial pneumonia (AIP) is clinically characterized by a rapid onset of respiratory failure and has a grave prognosis, with greater than 70% mortality in 3 months, despite mechanical ventilation. AIP is thought to be synonymous with Hamman-Rich syndrome, occurring in patients without preexisting lung diseases. It also physiologically resembles acute respiratory distress syndrome (ARDS) and occurs in a subset of patients with idiopathic ARDS. Chronic interstitial pneumonia is also known as usual interstitial pneumonia (UIP). It is characterized clinically by the insidious onset of a cough and shortness of breath that slowly progresses to respiratory failure and is characterized histopathologically by the random, nonuniform foci of inflammation and fibrosis of the lung. UIP is often observed in aged adults and in patients with a variety of conditions, including viral infections, rheumatoid diseases, and radiation treatment. Additionally, lethal UIP is often found in patients treated with chemotherapy. Bleomycin-and busulphan-induced 3,4 lung fibrosis has been reported in patients undergoing treatment for malignancies, such as squamous cell carcinoma and myeloid leukemia. Prevention of interstitial pneumonia/lung fibrosis is one of the most important issues in patients treated with chemotherapy.Histologically, diffuse infiltration of mononuclear and polymorphonuclear leukocytes into the lung is observed in the early stage of human interstitial pneumonia. Following the interstitial inflammation, florid fibroblast proliferation within both the interstitium and the alveolar space is found (proliferative stage). The same pathology is observed in the lung fibrosis animal model. [1][2][3][4][5][6][7][8] Thus, the interstitial inflammation is thought to be essential for the fibroblast proliferation of lung fibrosis. It has become clear that multiple mediators may be involved in establishing interstitial pneumonia/ lung fibrosis, including cytokines, chemokines, oxygen radicals, eicosanoids, prostaglandin, and apoptosis-related genes. 1-8 However, the pathogenesis of interstitial pneumonia is not well understood. Supported by Kurume University School of Medicine Alumni Foundation (Japan), the Ishibashi Foundation for the Promotion of Science (Tokyo, Japan), Kaibara Morikazu Medical Science Promotion Foundation (Fukuoka, Japan), Mitsui Medical Science Promotion Foundation (Tokyo, Japan), The Promotion and Mutual Aid Corporation for Private Schools of Japan, and Grant-in-Aid for Scientific Research on Priority Areas (C) "Medical Genome Science" from the Ministry of Education, Science, Sports and Culture of Japan (T.H.).
Reprints:Tomoaki Hoshino, Department of Internal Medicine 1, Kurume University School of Medicine, 67 Asahi-machi, Kurume 830-0011, Japan; email: hoshino@med.ku...