Pulmonary Manifestations of Systemic Disease: Mechanisms of Pulmonary Fibrosis |

The Role of Infection and Abnormal Immune Responses in Acute Exacerbation of Idiopathic Pulmonary Fibrosis FREE TO VIEW

Dong Weng, PhD; Huiping Li, MD
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Shanghai Pulmonary Hospital, Shanghai, China

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;149(4_S):A452. doi:10.1016/j.chest.2016.02.471
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SESSION TITLE: Mechanisms of Pulmonary Fibrosis

SESSION TYPE: Original Investigation Slide

PRESENTED ON: Sunday, April 17, 2016 at 09:45 AM - 11:15 AM

PURPOSE: Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) are severe events for patients with IPF with unkown etiology and pathogenesis, and are associated with high mortality. We studied changes in the immune function of IPF patients, and involvement of pathogens during AE-IPF episodes.

METHODS: 170 IPF patients (48 AE-IPF) and (122 stable-IPF) were recruited at Shanghai Pulmonary Hospital from April 2005 to August 2012. 70 healthy cases were included as controls. Immune function was assessed by: T cell subset ratio and absolute count; IgA, IgG, IgM and complement C3 and C4 levels; specific IgM antibody to a panel of microbial pathogens and pathogens in IPF patients sputum; serum cytokine levels. The patients were followed up until September 2014.

RESULTS: IPF patients showed increased total and absolute CD4+ T cells compared with controls. When compared with stable-IPF patients, AE-IPF patients exhibited a decrease in absolute CD3+ and CD4+ T cells/IPF patients displayed increased IgG and IgA levels, and decreased C3 and C4 levels compared with controls (P<0.05). The anti-viral/bacterial IgM was significantly higher in IPF compared to controls (P<0.05), and in AE-IPF compared with stable-IPF (P<0.05). A total of 38 bacterial strains were detected in IPF patient sputum without clinical signs of infection Bacteria-positive results were found in 9/48 (18.8%) of AE-IPF, in 26/122 (21.3%) stable-IPF. Most prominent were Gram-negative bacteria. There was no significant difference between AE-IPF and stable-IPF. A total of 57 different viruses were detected in nasopharyngeal swab of IPF patients. Virus-positive sputum results were found in 18/30 (60%) of tested AE-IPF and 13/30 (43.3) of tested stable-IPF. In AE-IPF, the majority of viruses were human herpes and influenza virus A, whereas it was predominantly human herpesviruses and human rhinovirus in stable-IPF patients. Compared with stable-IPF, AE-IPF patients showed increased IL-17, MIG and IL-9. There was significantly higher mortality of AE-IPF in one year (39.5%) compared to stable-IPF (28.7%). (P<0.05)

CONCLUSIONS: IPF patients had different sputum colonization with bacteria and/or latent infection and displayed abnormally activated immune response, which was exacerbated during AE-IPF. Abnormal immune activation, especially elevated IL-17A, MIG and IL-9 might play a role in exacerbation of IPF.

CLINICAL IMPLICATIONS: Potent anti-inflammatory and immunomodulatory therapy are critical in improving treatment success and reducing AE-IPF mortality.

DISCLOSURE: The following authors have nothing to disclose: Dong Weng, Huiping Li

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