Anti-RNA binding protein positivity in idiopathic interstitial pneumonia

Respir Med. 2019 Jan;146:23-27. doi: 10.1016/j.rmed.2018.11.015. Epub 2018 Nov 22.

Abstract

Introduction: Idiopathic interstitial pneumonias (IIP) are diffuse lung diseases whose cause is unknown and often present with features of autoimmunity despite not meeting criteria for a connective tissue disease (CTD). Recent studies suggest that anti-RNA binding protein (anti-RBP) antibodies, which include anti-SSA, anti-SSB, anti-Sm, and anti-RNP, play a role in the loss of immune tolerance and severity of pulmonary hypertension (PH) in CTDs. We hypothesized that anti-RBP positive (RBP+) subjects would have worse measures of lung function, radiographic findings, PH, and survival than anti-RBP negative (RBP-) subjects.

Methods: Subjects with both IIP and serologies for review were identified retrospectively and stratified based on anti-RBP antibody seropositivity. Baseline cohort characteristics, pulmonary function tests (PFT), ambulatory oxygen requirement, radiographic characteristics, markers of PH, and transplant-free survival were compared between anti-RBP positive and negative groups.

Results: Five hundred twenty patients with IIP were identified, of which ten percent (n = 53) were anti-RBP positive. RBP+ as compared to RBP- subjects had significantly worse PFTs as indicated by FEV1 (59.6 vs. 64.9, p = 0.046) and FVC (71.6 vs. 78.8, p = 0.018). There was a higher prevalence of radiographic honeycombing (49.1% vs. 38.3%, p = 0.006) and emphysema (22.6% vs. 5.1%, p < 0.001) in the RBP+ group despite no difference in smoking history. The Pulmonary Artery-Aorta ratio was also larger in the RBP+ group (0.93 vs. 0.88, p = 0.040). There was no difference in transplant-free survival between groups (log rank = 0.912).

Conclusion: Anti-RBP+ IIP patients may have worse lung function, increased chest radiographic abnormalities, and PH compared with those without these antibodies.

Keywords: Anti-RNA binding protein antibodies; Idiopathic interstitial pneumonia; Interstitial lung disease.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Antibodies, Antinuclear / immunology
  • Autoimmunity / immunology
  • Carrier Proteins / blood
  • Carrier Proteins / metabolism*
  • Connective Tissue Diseases / epidemiology
  • Female
  • Humans
  • Hypertension, Pulmonary / physiopathology
  • Idiopathic Interstitial Pneumonias / blood*
  • Idiopathic Interstitial Pneumonias / diagnostic imaging
  • Idiopathic Interstitial Pneumonias / epidemiology*
  • Idiopathic Interstitial Pneumonias / physiopathology*
  • Lung / blood supply
  • Lung / diagnostic imaging
  • Lung / physiopathology
  • Male
  • Middle Aged
  • Prevalence
  • Radiography, Thoracic / methods
  • Respiratory Function Tests / methods
  • Retrospective Studies
  • Tomography, X-Ray Computed

Substances

  • Antibodies, Antinuclear
  • Carrier Proteins