Idiopathic Pulmonary Fibrosis Pathogenesis and Novel Approaches to Immunomodulation

A Serological Neoepitope Biomarker of Neutrophil Elastase-Degraded Calprotectin, Associated with Neutrophil Activity, Identifies Idiopathic Pulmonary Fibrosis and Chronic Obstructive Pulmonary Disease More Effectively Than Total Calprotectin

Neutrophil activation can release neutrophil extracellular traps (NETs) in acute inflammation. NETs result in the release of human neutrophil elastase (HNE) and calprotectin, where the former can degrade the latter and generate protein fragments associated with neutrophil activity. We investigated this in chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) using the novel neoepitope biomarker CPa9-HNE, quantifying a specific HNE-mediated fragment of calprotectin in serum. CPa9-HNE was compared to total calprotectin. Initially, CPa9-HNE was measured in healthy (n = 39), COPD (n = 67), and IPF (n = 16) serum using a neoepitope-specific competitive enzyme-linked immunosorbent assay. Then, a head-to-head comparison of CPa9-HNE and total calprotectin, a non-neoepitope, was conducted in healthy (n = 19), COPD (n = 25), and IPF (n = 19) participants. CPa9-HNE levels were significantly increased in COPD (p < 0.0001) and IPF subjects (p = 0.0001) when compared to healthy participants. Additionally, CPa9-HNE distinguished IPF (p < 0.0001) and COPD (p < 0.0001) from healthy participants more effectively than total calprotectin for IPF (p = 0.0051) and COPD (p = 0.0069). Here, CPa9-HNE also distinguished IPF from COPD (p = 0.045) participants, which was not observed for total calprotectin (p = 0.98). Neutrophil activity was significantly higher, as assessed via serum CPa9-HNE, for COPD and IPF compared to healthy participants. Additionally, CPa9-HNE exceeded the ability of non-neoepitope calprotectin serum measurements to separate healthy from lung disease and even COPD from IPF participants, indicating that neutrophil activity is essential for both COPD and IPF.

The road to hell is paved with good intentions: a look back at the PANTHER-IPF trial

The PANTHER-IPF trial was a turning point in treatment of idiopathic pulmonary fibrosis (#IPF) highlighting the importance of randomised controlled trials in determining treatment strategies, even for rare diseases and/or potentially fatal acute events https://bit.ly/3Oi0KwD.

Acute exacerbations of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and ultimately fatal disease, with a highly variable course in individual patients. Episodes of rapid deterioration are not uncommon, often following a period of stability. In cases of uncertain etiology, with typical clinical and high-resolution computed tomography (HRCT) features, the term 'acute exacerbation of IPF' (AE-IPF) has been coined to describe a combination of diffuse alveolar damage and preexisting usual interstitial pneumonia. In 2007, a consensus definition and diagnostic criteria were proposed. Although the presence of overt infection is currently an exclusion criterion, it appears likely that occult infection, reflux and thoracic surgical procedures are all trigger factors for AE-IPF. The development of new, usually bilateral infiltrates (ground-glass attenuation with variable admixed consolidation) is a defining HRCT feature. The outcome is poor with a short-term mortality in excess of 50% despite therapy. A number of pathophysiologic pathways are activated, with immunologic dysregulation, epithelial damage and circulating fibrocytes all believed to play a pathogenetic role. Acute exacerbations are less prevalent in other fibrotic lung diseases than in IPF and may have a better outcome, with the exception of acute exacerbations of rheumatoid lung. In AE-IPF, the exclusion of alternative causes of rapid deterioration, including heart failure and infection, is the main goal of investigation. Empirical high-dose corticosteroid steroid therapy is generally used in AE-IPF, without proven benefit.