Viruses and acute exacerbations of idiopathic pulmonary fibrosis: rest in peace?

The Role of Infection in Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Background

Acute exacerbation of IPF (AE-IPF) is associated with high mortality. We studied changes in pathogen involvement during AE-IPF and explored a possible role of infection in AE-IPF.

Objectives

Our purpose is to investigate the role of infection in AE-IPF.

Methods

Overall, we recruited 170 IPF patients (48 AE-IPF, 122 stable) and 70 controls at Shanghai Pulmonary Hospital. Specific IgM against microbial pathogens and pathogens in sputum were assessed. RNA sequences of pathogens in nasopharyngeal swab of IPF patients were detected by PathChip. A panel of serum parameters reflecting immune function were assessed.

Results

Antiviral/bacterial IgM was higher in IPF vs. controls and in AE-IPF vs. stable IPF. Thirty-eight different bacterial strains were detected in IPF patient sputum. Bacteria-positive results were found in 9/48 (18.8%) of AE-IPF and in 26/122 (21.3%) stable IPF. Fifty-seven different viruses were detected in nasopharyngeal swabs of IPF patients. Virus-positive nasopharyngeal swabs were found in 18/30 (60%) of tested AE-IPF and in 13/30 (43.3%) of stable IPF. AE-IPF showed increased inflammatory cytokines (IL-6, IFN-γ, MIG, IL-17, and IL-9) vs. stable IPF and controls. Mortality of AE-IPF in one year (39.5%) was higher compared to stable IPF (28.7%).Conclusions. IPF patients had different colonization with pathogens in sputum and nasopharyngeal swabs; they also displayed abnormally activated immune response, which was exacerbated during AE-IPF.

Impairment of Immunoproteasome Function by Cigarette Smoke and in Chronic Obstructive Pulmonary Disease

RATIONALE

Patients with chronic obstructive pulmonary disease (COPD) and in particular smokers are more susceptible to respiratory infections contributing to acute exacerbations of disease. The immunoproteasome is a specialized type of proteasome destined to improve major histocompatibility complex (MHC) class I-mediated antigen presentation for the resolution of intracellular infections.

OBJECTIVES

To characterize immunoproteasome function in COPD and its regulation by cigarette smoke.

METHODS

Immunoproteasome expression and activity were determined in bronchoalveolar lavage (BAL) and lungs of human donors and patients with COPD or idiopathic pulmonary fibrosis (IPF), as well as in cigarette smoke-exposed mice. Smoke-mediated alterations of immunoproteasome activity and MHC I surface expression were analyzed in human blood-derived macrophages. Immunoproteasome-specific MHC I antigen presentation was evaluated in spleen and lung immune cells that had been smoke-exposed in vitro or in vivo.

MEASUREMENTS AND MAIN RESULTS

Immunoproteasome and MHC I mRNA expression was reduced in BAL cells of patients with COPD and in isolated alveolar macrophages of patients with COPD or IPF. Exposure of immune cells to cigarette smoke extract in vitro reduced immunoproteasome activity and impaired immunoproteasome-specific MHC I antigen presentation. In vivo, acute cigarette smoke exposure dynamically regulated immunoproteasome function and MHC I antigen presentation in mouse BAL cells. End-stage COPD lungs showed markedly impaired immunoproteasome activities.

CONCLUSIONS

We here show that the activity of the immunoproteasome is impaired by cigarette smoke resulting in reduced MHC I antigen presentation. Regulation of immunoproteasome function by cigarette smoke may thus alter adaptive immune responses and add to prolonged infections and exacerbations in COPD and IPF.

Streptococcus pneumoniae triggers progression of pulmonary fibrosis through pneumolysin

RATIONALE

Respiratory tract infections are common in patients suffering from pulmonary fibrosis. The interplay between bacterial infection and fibrosis is characterised poorly.

OBJECTIVES

To assess the effect of Gram-positive bacterial infection on fibrosis exacerbation in mice.

METHODS

Fibrosis progression in response to Streptococcus pneumoniae was examined in two different mouse models of pulmonary fibrosis.

MEASUREMENTS AND MAIN RESULTS

We demonstrate that wild-type mice exposed to adenoviral vector delivery of active transforming growth factor-β1 (TGFß1) or diphteria toxin (DT) treatment of transgenic mice expressing the DT receptor (DTR) under control of the surfactant protein C (SPC) promoter (SPC-DTR) to induce pulmonary fibrosis developed progressive fibrosis following infection with Spn, without exhibiting impaired lung protective immunity against Spn. Antibiotic treatment abolished infection-induced fibrosis progression. The cytotoxin pneumolysin (Ply) of Spn caused this phenomenon in a TLR4-independent manner, as Spn lacking Ply (SpnΔply) failed to trigger progressive fibrogenesis, whereas purified recombinant Ply did. Progressive fibrogenesis was also observed in AdTGFβ1-exposed Ply-challenged TLR4 KO mice. Increased apoptotic cell death of alveolar epithelial cells along with an attenuated intrapulmonary release of antifibrogenic prostaglandin E2 was found to underlie progressive fibrogenesis in Ply-challenged AdTGFβ1-exposed mice. Importantly, vaccination of mice with the non-cytotoxic Ply derivative B (PdB) substantially attenuated Ply-induced progression of lung fibrosis in AdTGFβ1-exposed mice.

CONCLUSIONS

Our data unravel a novel mechanism by which infection with Spn through Ply release induces progression of established lung fibrosis, which can be attenuated by protein-based vaccination of mice.

Acute exacerbation of idiopathic pulmonary fibrosis-a review of current and novel pharmacotherapies

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive form of lung disease of unknown etiology for which a paucity of therapies suggest benefit, and for which none have demonstrated improved survival. Acute exacerbation of IPF (AE-IPF) is defined as a sudden acceleration of the disease or an idiopathic acute injury superimposed on diseased lung that leads to a significant decline in lung function. An AE-IPF is associated with a mortality rate as high as 85% with mean survival periods of between 3 to 13 days. Under these circumstances, mechanical ventilation (MV) is controversial, unless used a as a bridge to lung transplantation. Judicious fluid management may be helpful. Pharmaceutical treatment regimens for AE-IPF include the use of high dose corticosteroids with or without immunosuppressive agents such as cyclosporine A (CsA), and broad spectrum antibiotics, despite the lack of convincing evidence demonstrating benefit. Newer research focuses on abnormal wound healing as a cause of fibrosis and preventing fibrosis itself through blocking growth factors and their downstream intra-cellular signaling pathways. Several novel pharmaceutical approaches are discussed.

Aclidinium bromide for the treatment of chronic obstructive pulmonary disease

INTRODUCTION

Although there are some challenges with current therapies, the growing evidence that tiotropium bromide is important in the maintenance treatment of chronic obstructive pulmonary disease (COPD) has led to enthusiastic investigation in search of novel muscarinic antagonists which share some of the beneficial characteristics of tiotropium and perhaps improve upon less desirable ones.

AREAS COVERED

Aclidinium bromide is a new muscarinic antagonist that has been developed to relieve symptoms in patients with COPD. Preclinical data showed that it has an intriguing pharmacodynamic and pharmacokinetic profile. Aclidinium bromide was initially assessed as a once-daily bronchodilator. Subsequently, it has been evaluated as a twice-daily agent to increase the size of the clinical effect. Pivotal Phase III trials have documented that aclidinium bromide 400 μg twice-daily shows clinically meaningful effects in lung function and other important supportive outcomes, such as health-related quality of life, dyspnea and night-time/early morning symptoms, and is safe.

EXPERT OPINION

Aclidinium bromide can to be used as an alternative to tiotropium or a long-acting β₂-agonist. It is likely that the device used to deliver aclidinium, Genuair inhaler, a novel, multidose and a breath-actuated dry powder inhaler (DPI), will be important for the possible success of this drug. However, additional Phase III trials to assess advantages over tiotropium bromide and long-acting β₂-agonists are required to allow the place of aclidinium bromide to be fully elucidated.

Houttuynia cordata inhibits lipopolysaccharide-induced rapid pulmonary fibrosis by up-regulating IFN-γ and inhibiting the TGF-β1/Smad pathway

This study aimed to explore the effect and mechanism of H. cordata vapor extract on acute lung injury (ALI) and rapid pulmonary fibrosis (RPF). We applied the volatile extract of HC to an RPF rat model and analyzed the effect on ALI and RPF using hematoxylin-eosin (H&E) staining, routine blood tests, a cell count of bronchoalveolar lavage fluid (BALF), lactate dehydrogenase (LDH) content, van Gieson (VG) staining, hydroxyproline (Hyp) content and the dry/wet weight ratio. The expression of IFN-γ/STAT(1), IL-4/STAT(6) and TGF-β(1)/Smads was analyzed using ELISA, immunohistochemistry and western blotting methods. The active ingredients of the HC vapor extract were analyzed using a gas chromatograph-mass spectrometer (GC-MS), and the effects of the active ingredients of HC on the viability of NIH/3T3 and RAW264.7 cells were detected using an MTT assay. The active ingredients of the HC vapor extract included 4-terpineol, α-terpineol, l-bornyl acetate and methyl-n-nonyl ketone. The results of the lung H&E staining, Hyp content, dry/wet weight ratio and VG staining suggested that the HC vapor extract repaired lung injury and reduced RPF in a dose-dependent manner and up-regulated IFN-γ and inhibited the TGF-β1/Smad pathway in vivo. In vitro, it could inhibit the viability of RAW264.7 and NIH/3T3 cells. It also dose-dependently inhibited the expression of TGF-β1 and enhanced the expression of IFN-γ in NIH/3T3. The HC vapor extract inhibited LPS-induced RPF by up-regulating IFN-γ and inhibiting the TGF-β1/Smad pathway.