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COPD: from genetics to old age
S64 Circulating polymers are found in alpha-1-antitrypsin deficiency and are associated with lung disease
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  1. JA Dickens1,
  2. L Tan1,
  3. DL DeMeo2,
  4. E Miranda3,
  5. J Perez4,
  6. ST Rashid1,
  7. J Day1,
  8. A Ordonez1,
  9. SJ Marciniak1,
  10. I Haq1,
  11. AF Barker5,
  12. EJ Campbell6,
  13. E Eden7,
  14. NG McElvaney8,
  15. SI Rennard9,
  16. RA Sandhaus10,
  17. JM Stocks11,
  18. JK Stoller12,
  19. C Strange13,
  20. G Turino7,
  21. FN Rouhani14,
  22. M Brantly14,
  23. DA Lomas1
  1. 1University of Cambridge, Cambridge, UK
  2. 2Brigham and Women's Hospital, Boston, USA
  3. 3University of Rome La Sapienza, Rome, Italy
  4. 4University of Malaga, Malaga, Spain
  5. 5Oregon Health and Science University, Portland, USA
  6. 6Intermountain Health Care and HerediLab Inc.,, Provo and Salt Lake City, USA
  7. 7St. Luke’s/Roosevelt Hospital, New York City, USA
  8. 8Beaumont Hospital, Dublin, Ireland
  9. 9University of Nebraska, Omaha, USA
  10. 10National Jewish Health, Denver, USA
  11. 11University of Texas, Tyler, USA
  12. 12Cleveland Clinic, Cleveland, USA
  13. 13Medical University of South Carolina, Charleston, USA
  14. 14University of Florida, Gainesville, USA

Abstract

Introduction and Objectives The severe Z deficiency allele of alpha-1-antitrypsin (Glu342Lys) results in the formation of polymers that are retained within hepatocytes, leading to hepatitis, cirrhosis and hepatocellular carcinoma. The concomitant lack of circulating protein predisposes to early onset emphysema. Polymers are also found in the lung, skin and kidney and are known to be proinflammatory, but it is unknown whether those polymers are produced locally or are deposited from a circulating source. We wished to establish whether polymers are present in the plasma of individuals with alpha-1-antitrypsin deficiency, from where they originate and whether they are associated with any clinical phenotype.

Methods We used a novel anti-alpha-1-antitrypsin polymer monoclonal antibody (2C1) in an ELISA assay to evaluate whether polymers are present in a cohort of 513 individuals with ZZ alpha-1-antitrypsin deficiency. Serial samples from an individual with ZZ alpha-1-antitrypsin deficiency undergoing liver transplantation were used to investigate the source of circulating polymers. We then used a 2nd cohort of 293 individuals with mixed alpha-1-antitrypsin phenotypes to determine whether circulating polymers could be used as a screening test for the presence of a polymerogenic allele. Disease associations were sought using clinical data from the ZZ alpha-1-antitrypsin deficient cohort.

Results In the cohort of 513 individuals with PiZZ alpha-1-antitrypsin deficiency, we found 512 had quantifiable polymers present within serum, the 513th having previously had a liver transplant. Circulating polymer levels were higher in men and individuals with COPD and a there was a correlation with older age and lower lung function. The presence of circulating polymers was 100% sensitive and 89% specific in identifying 20 PiZZ alpha-1-antitrypsin homozygotes in a mix of 293 alpha-1-antitrypsin genotypes. Serial blood samples from a PiZZ individual undergoing liver transplantation showed that circulating polymers originate from the liver, clearing with a half-life of approximately 30 hours and becoming undetectable 5 days after transplantation.

Conclusions We have shown that circulating polymers are present in PiZZ alpha-1-antitrypsin individuals and originate from the liver. Polymer levels are associated with COPD, suggesting they may play a role in disease pathogenesis.

Abstract S64 Figure 1.
Abstract S64 Figure 1.

Z α1 antitrypsin polymers are present in the circulation and are cleared following liver transplantation. Mouse monoclonal antibodies that detect all conformers of α1-antitrypsin, or only polymeric (α1-antitrypsin (2C1), were used to quantify total (α1-antitrypsin and (α1-antitrypsin polymers respectively using sandwich ELISA. Time points marked * are below the lower limit of quantification (0.4 ug/mL).

https://doi.org/10.1136/thoraxjnl-2013-204457.71

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