Background: ADAM28, ADAM33, IL-13, IL-4 and other cytokines (IL-6 and IL-10) seem to play important roles in the persistence and maintenance of acute inflammatory processes that ultimately lead to lung remodeling and pulmonary fibrosis, which may be responsible for the high morbidity and mortality rates associated with non-pandemic acute viral pneumonias in childhood. Objectives: The aim of this study was to evaluate the roles of ADAM33, ADAM28, IL4, IL6, IL10 and IL13 in the development of inflammation and alveolar fibrosis due to lethal acute respiratory infections of the lower airway in a pediatric population, especially in those with viral etiology. Study design: For this study, 193 cases were selected, and samples from the cases were processed for viral antigen detection by immunohistochemistry and then separated into two groups: virus-positive (n=68) and virus-negative (n=125). Immunohistochemistry was performed to assess the presence of metalloproteinases (ADAM33 and ADAM28) and inflammatory cytokines (IL-4, IL-13, IL-6, IL-10) in the alveolar septa. Results: The virus-positive group showed stronger immunolabeling for ADAM33, ADAM28, IL-4 and IL-13 (p<. 0.0001 for all variables). The staining intensities for ADAM33 and ADAM28 were directly proportional to the intensities for IL-4 and IL-13 (p<. 0.0001). Conclusions: The results of this study suggest that these proteins play important roles in pulmonary inflammatory reactions elicited against etiological viral agents. In addition, these mediators may affect the process of lung remodeling and the development of pulmonary fibrosis.