Cytokine Profiling in Influenza A Virus and Staphylococcal (Co-)Infections

Abstract. Influenza A virus and Staphylococcus aureus are common causative agents of pneumonia. Co-infections with these two pathogens frequently occur and are characterized, among others, by higher morbidity and mortality due to hyper-inflammation of the lungs. Here, we aimed to profile systemic and local cytokine composition at early acute stages of pneumonia in a murine model. All mice recovered from single influenza A virus and/or staphylococcal infections. In contrast, co-infections led to a severe clinical outcome. While distinct cytokine patterns were detected in lungs of single-pathogen-infected animals, co-infections combined both virus- and bacteria-driven responses. However, analyses of infected human primary monocytic cells as well as bronchial epithelial cells did not reflect murine profiles. Based on infectious dose, mainly bacteria-driven responses were noted. The impact of single cells to cytokine composition of the lungs and translation of murine studies to humans remains uncertain and warrants further studies.