Relationship between Neutrophil Gelatinase-Associated Lipocalin, Eosinophil Cationic Protein, Cytokines, and Atopic Sensitization in Patients with Allergic Diseases

The effect of neutrophil gelatinase-associated lipocalin (NGAL) on eosinophil activation, atopic sensitization, and systemic inflammation in allergic diseases has rarely been investigated. This study aimed to investigate the relationship between NGAL, eosinophil cationic protein (ECP), cytokines, and allergen-specific immunoglobulin E (sIgE) in allergic diseases. A total of 136 patients with allergies and 58 healthy individuals were evaluated. The concentrations of NGAL, ECP, tumor necrosis factor-α (TNF-α), interleukin-5 (IL-5), sIgE, total IgE (tIgE), and high-sensitivity C-reactive protein (hsCRP) were measured. The transforming growth factor-β1 (TGF-β1) level was measured as a profibrotic marker of bronchial asthma. Allergic patients had significantly higher NGAL, ECP, and hsCRP levels than healthy individuals. However, there was no significant difference in NGAL levels between patients with positive and negative ECP tests and those with high and low sIgE scores. Asthmatic patients with elevated NGAL exhibited a significantly higher TGF-β1 level than those without elevated NGAL. However, no significant difference was observed in the ECP, IL-5, and sIgE levels between the two groups. Among the patients with a positive ECP test, subjects with elevated hsCRP had two times higher NGAL levels than those without elevated hsCRP. NGAL was positively correlated with TNF-α, TGF-β1, and hsCRP, but not with ECP, IL-5, tIgE, and sIgE. An elevated NGAL level led to a 1.3-fold increase in the prevalence of high TGF-β1 (odds ratio: 1.31; 95% CI: 1.04–2.58; P < 0.001). In conclusion, NGAL elevation may be more closely linked to allergic inflammation and a possible fibrotic change in the airways than to the severity of eosinophil activation and atopic sensitization.