Surfactant protein-D and polymorphonuclear leukocyte elastase concentrations in patients with septic acute respiratory distress syndrome

Purpose: Inhibition of surfactant activities by the protein in pulmonary edematous fluid plays a role in the occurrence of respiratory failure in acute respiratory distress syndrome (ARDS). Polymorphonuclear (PMN) elastase may be involved in surfactant-mediated damage. Accordingly, the concentrations of surfactant protein-D (SP-D) and PMN elastase were determined in patients with sepsis, and the associations of these two factors with the occurrence of ARDS and prognosis were examined. Methods: Blood samples from 33 patients with sepsis and with or without ARDS were assayed. The SP-D and PMN elastase levels were determined using an enzyme-linked immunosorbent assay. Results: SP-D levels in groups with and without ARDS were 493.9 ± 373.3 ng/ml and 91.8 ± 30.1 ng/ml, respectively. The level in the ARDS group was significantly higher than that in the group withFrom the Department of Emergency and Critical Care Medicine, Akita University School of Medicine, Japan (Dr. Hajime Nakae), Department of Critical Care Medicine, Iwate Medical University, School of Medicine, Japan (Drs. Shigeatsu Endo, Nobuhiro Sato, Hajimu Abe, and Satoko Imai), Department of Surgery, Keio University School of Medicine, Japan (Dr. Go Wakabayashi) and Department of Surgery, Isawa Hospital, Japan (Dr. Michihiko Kitamura). Address requests for reprints to: Shigeatsu Endo, MD, Department Critical Care Medicine, Iwate Medical University School of Medicine, 19-1 Uchimaru, Moiroka 020-8505, Japan Tel 81-19-651-5111. Fax 81-19-651-5151. E-mail: sendo@iwate-med.ac. jp out ARDS (P = .0002). The PMN elastase levels in the groups with and without ARDS were 845.1 ± 294.0 ng/ml and 424.9 ± 81.1 ng/ml, respectively. The level in the ARDS group was significantly higher than that in the group without ARDS (P < .0001). The SP-D level in patients who survived was 157.0 ± 127.4 ng/ml and that in those who died was 625.5 ± 433.2 ng/ml. The level in the latter group was significantly higher than that in the former (P < .0001). The PMN elastase level in patients who survived was 493.7 ± 145.8 ng/ml and that in those who died was 980.9 ± 300.9 ng/ml. The level in the latter group was significantly higher than that in the former (P < .0001). A significant correlation was observed between SP-D and the PMN elastase levels (r = 0.818, P < .0001). Conclusion: In the presence of ARDS, SP-D and PMN elastase served as good indicators of severity. Original Article the alveolar space. During this process, protease, active oxygen species and leukotrienes are released from the neutrophils and induce extensive non-specific inflammatory reactions in endothelial cells of pulmonary capillary vessels and type I cells of the alveolar septum, thereby inducing pulmonary edema resulting from accelerated permeability [1]. PMN elastase is one of the lysosomal enzymes contained in the azurophilic granules of neutrophils, and is believed to play an important role in the pulmonary tissue damage associated with neutrophils. We previously reported PMN elastase to be involved in the development of ARDS [2-3]. Pulmonary surfactant prevents alveolar collapse and maintains gas exchange in the lungs. Apoproteins are essential for manifestation of the functions of pulmonary sur