Granzyme K - A novel marker to identify the presence and rupture of abdominal aortic aneurysm

Background: Immune inflammatory dysfunction is a hallmark of abdominal aortic aneurysm (AAA). Granzyme K (GZMK) is involved in the regulation of inflammation. However, the correlation between GZMK expression and AAA risk remains unknown.

Methods: This case-control study included 112 AAA patients and 112 controls. Serum GZMK levels were determined by enzyme-linked immunosorbent assay and immunohistochemistry was utilized to determine GZMK expression in aortic tissues.

Results: Compared with controls, AAA patients had higher levels of serum GZMK, and GZMK expression in AAA tissues was increased and positively associated with its serum levels (r = 0.688, P = 0.019). A positive association of serum GZMK levels with CRP or AAA diameter was confirmed, while there was a relationship between tissue GZMK expression and AAA diameter. The AUC of serum GZMK for AAA diagnosis was 0.78 with the sensitivity and specificity of 62.5% and 81.2%, whereas AUC for rupture detection was 0.76 with a sensitivity of 90.0% and specificity of 51.3%. A combination of clinically used inflammatory parameters with serum GZMK could enhance the accuracy of WBC or CRP alone in detecting AAA or rupture type. Multiple logistic analyses revealed an association of per unit increase of serum GZMK with AAA presence (OR = 1.046, P < 0.001) and its rupture risk (OR = 1.015, P = 0.048) after adjusting for confounding factors.

Conclusions: Our study provides proof that elevated GZMK expression both in serum and tissues is correlated with the presence of AAA, and serum GZMK may be a useful non-invasive marker that helps to identify AAA and its rupture risk in clinical practice.