Genetic replacement of surfactant protein-C reduces respiratory syncytial virus induced lung injury

• Published in: Respiratory research 2013-02, Vol.14 (1), p.19-19
• Main Authors: Glasser, Stephan W, Senft, Albert P, Maxfield, Melissa D, Ruetschilling, Teah L, Baatz, John E, Page, Kristen, Korfhagen, Thomas R
• Format: Article
• Language: English
• Subjects: Alveoli; Animals; Cells, Cultured; Complications and side effects; Diseases; Down-Regulation - genetics; Genes; Genetic aspects; Health aspects; Immune system; Lung diseases, Interstitial; Lung Injury - genetics; Lung Injury - metabolism; Lung Injury - prevention & control; Lungs; Medical research; Medicine, Experimental; Mice; Mice, 129 Strain; Mice, Transgenic; Mutation; Physiological aspects; Prevention; Proteins; Pulmonary surfactant; Pulmonary Surfactant-Associated Protein C - biosynthesis; Pulmonary Surfactant-Associated Protein C - genetics; Respiratory syncytial virus; Respiratory syncytial virus infection; Respiratory Syncytial Virus Infections - genetics; Respiratory Syncytial Virus Infections - metabolism; Respiratory Syncytial Virus Infections - prevention & control; Respiratory Syncytial Viruses; Rodents; Surfactants; Viral infections; Viral Load - methods
• ISSN: 1465-9921; 1465-993X; 1465-993X; 1465-9921
• DOI: 10.1186/1465-9921-14-19

Individuals with deficiencies of pulmonary surfactant protein C (SP-C) develop interstitial lung disease (ILD) that is exacerbated by viral infections including respiratory syncytial virus (RSV). SP-C gene targeted mice (Sftpc -/-) lack SP-C, develop an ILD-like disease and are susceptible to infection with RSV. In order to determine requirements for correction of RSV induced injury we have generated compound transgenic mice where SP-C expression can be induced on the Sftpc -/- background (SP-C/Sftpc -/-) by the administration of doxycycline (dox). The pattern of induced SP-C expression was determined by immunohistochemistry and processing by Western blot analysis. Tissue and cellular inflammation was measured following RSV infection and the RSV-induced cytokine response of isolated Sftpc +/+ and -/- type II cells determined. After 5 days of dox administration transgene SP-C mRNA expression was detected by RT-PCR in the lungs of two independent lines of bitransgenic SP-C/Sftpc -/- mice (lines 55.3 and 54.2). ProSP-C was expressed in the lung, and mature SP-C was detected by Western blot analysis of the lavage fluid from both lines of SP-C/Sftpc -/- mice. Induced SP-C expression was localized to alveolar type II cells by immunostaining with an antibody to proSP-C. Line 55.3 SP-C/Sftpc -/- mice were maintained on or off dox for 7 days and infected with 2.6x107 RSV pfu. On day 3 post RSV infection total inflammatory cell counts were reduced in the lavage of dox treated 55.3 SP-C/Sftpc -/- mice (p = 0.004). The percentage of neutrophils was reduced (p = 0.05). The viral titers of lung homogenates from dox treated 55.3 SP-C/Sftpc -/- mice were decreased relative to 55.3 SP-C/Sftpc -/- mice without dox (p = 0.01). The cytokine response of Sftpc -/- type II cells to RSV was increased over that of Sftpc +/+ cells. Transgenic restoration of SP-C reduced inflammation and improved viral clearance in the lungs of SP-C deficient mice. The loss of SP-C in alveolar type II cells compromises their response to infection. These findings show that the restoration of SP-C in Sftpc -/- mice in response to RSV infection is a useful model to determine parameters for therapeutic intervention.