YKL-40—a secreted human glycoprotein also known as Chitinase-3-like protein 1 (CHI3L1)—is a potential biomarker of inflammation and mortality in patients suffering from inflammatory lung disease and COPD, according to new research in BMC Pulmonary Medicine.

Researchers followed 493 patients with moderate to very severe COPD for up to 10 years, in order to investigate the association between high plasma YKL-40 and increased mortality in patients with moderate to very severe COPD.

For the study, patients were divided into two groups according to plasma YKL-40: normal levels and high levels (a concentration higher than the 75th percentile for age-matched healthy subjects). Outcome was overall survival (OS) and was evaluated in uni- and multivariate proportional hazards Cox regression analyses and adjusted for factors affecting mortality.

The study found that median plasma YKL-40 was increased in patients with COPD (81 ng/ml, p <0.001) compared to healthy subjects (40 ng/ml).

Patients with high plasma YKL-40 had a hazard ratio (HR) of 1.42 (95% CI: 1.15-1.75, p = 0.001) for all-cause mortality. Multivariate analysis showed that the following were independent prognostic markers of OS:

  • YKL-40 (HR 1.38; 95% CI: 1.11-1.72, p = 0.004);
  • Age (HR 1.05; 95% CI: 1.03-1.06, p <0.0001);
  • Severe COPD (HR 1.35; 95 CI: 1.03-1.76, p = 0.03);
  • Very severe COPD (HR 2.19; 95% CI: 1.60 – 2.99 <0.0001);
  • Neutrophil granulocyte count (HR 1.05; 95% CI: 1.01-1.08, p = 0.01);
  • Smoking history of >40 years (HR 1.38; 95% CI: 1.11-1.71, p = 0.003).

“High plasma YKL-40 is associated with increased mortality in patients with moderate to very severe COPD, suggesting a role for YKL-40 as a potential biomarker of mortality in this patient group,” the authors concluded.