NUCLEAR FACTOR-KAPPA-B IS ACTIVATED IN ALVEOLAR MACROPHAGES FROM PATIENTS WITH ACUTE RESPIRATORY-DISTRESS SYNDROME

Objective: The expression of proinflammatory cytokines is rapidly incr eased in experimental models of the acute respiratory distress syndrom e (ARDS), in patients at risk for ARDS, and in patients with establish ed ARDS. Because multiple cytokines are present in bronchoalveolar lav age fluid, a common, proximal activation mechanism may operate in thes e settings. The proinflammatory cytokines whose expression is increase d in the lungs of patients with ARDS have binding sequences in their e nhancer/promoter regions for transcriptional regulatory proteins, such as nuclear factor-kappa B (NF-kappa B), nuclear factor-IL6 (NF-IL6), cyclic adenosine monophosphate responsive element binding protein, ser um protein-1, and activating protein-1. To test the hypothesis that ac tivation of one or more of these nuclear transcriptional regulatory fa ctors might provide a common mechanism for the simultaneous expression of multiple cytokine genes in the setting of ARDS, we measured activa tion of these factors in alveolar macrophages from patients with ARDS and from controls. Design: Prospective, clinical study. Setting: Medic al and surgical intensive care units at a university hospital and a co unty hospital. Patients: Twelve patients, six with established ARDS an d six control patients without lung injury. Interventions: Patients wi th ARDS and controls underwent fiberoptic bronchoscopy and bronchoalve olar ravage. Alveolar macrophages were isolated from ravage fluid and the nuclear proteins were extracted. Activation of transcriptional fac tors NF-kappa B, NF-IL6, cyclic adenosine monophosphate responsive ele ment binding protein, activating protein-1, and serum protein-1 was de termined using an electrophoretic mobility shift assay, followed by de nsitometry of the autoradiographed gels. Measurements and Main Results : There were no significant differences in gender, age, tobacco smokin g, Acute Physiology and Chronic Health Evaluation II score, quantity o f lavage fluid, or number of alveolar macrophages in lavage specimens in the patient groups. Acute Lung Injury score and the Pao(2)/Flo(2) r atio differed significantly between controls and ARDS patients: 0.46 /- 0.17 vs. 2.74 +/- 0.14 (p<.0001) and 310 +/- 45 torr (41.3 +/- 6.0 kPa) vs. 150 +/- 11 torr (21.3 +/- 1.5 kPa) (p < .006), respectively. The mean FlO(2) of the control patients was not significantly differen t from the mean FlO(2) of ARDS patients: 0.47 +/- 0.11 vs. 0.55 +/- 0. 6 (p =.53). Patients with ARDS had significantly (p <.02) increased ac tivation of NF-kappa B in alveolar macrophages compared with patients without the syndrome. There was no evidence of increased activation of the transcriptional factors activating protein-1, serum protein-1, NF -IL6, or cyclic adenosine monophosphate responsive element binding pro tein in alveolar macrophages from ARDS vs. control patients. Conclusio ns: These experiments demonstrated increased in vivo activation of the nuclear transcriptional regulatory factor NF-kappa B (but not NF-IL6, cyclic adenosine monophosphate responsive element binding protein, ac tivating protein-1, or serum protein-1) in alveolar macrophages from p atients with ARDS. Because binding sequences for NF-kappa B are presen t in the enhancer/promoter sequences of multiple proinflammatory cytok ines, activation of NF-kappa B may contribute to the increased express ion of multiple cytokines in the lung in the setting of established AR DS.