Lipocalin-2 and insulin as new biomarkers of alopecia areata

Lipocalin-2 and visfatin are proinflammatory adipokines involved in the regulation of glucose homeostasis. Their role has been described in numerous inflammatory skin diseases such as atopic dermatitis and psoriasis. Recently, an increased prevalence of metabolic abnormalities has been reported in patients with alopecia areata. The aim of the study is to determine the serum levels of lipocalin-2 and visfatin in patients with alopecia areata in comparison with healthy controls. Moreover, the serum levels of total cholesterol, low-density lipoprotein cholesterol (LDL-cholesterol), high-density lipoprotein cholesterol (HDL-cholesterol), triglycerides, fasting glucose, insulin, c-peptide, and homeostasis model assessment for insulin resistance (HOMA-IR) were evaluated. Fifty-two patients with alopecia areata and 17 control subjects were enrolled in the study. The serum levels of lipocalin-2 [mean ± standard deviation, SD: 224.55 ± 53.58 ng/ml vs. 188.64 ± 44.75, p = 0.01], insulin [median (interquartile range, IQR): 6.85 (4.7–9.8) μIU/ml vs. 4.5 (3.5–6.6), p<0.05], c-peptide [median (IQR): 1.63 (1.23–2.36) ng/ml vs. 1.37 (1.1–1.58), p<0.05)], and HOMA-IR [median (IQR): 1.44 (0.98–2.15) vs. 0.92 (0.79–1.44), p<0.05) were significantly higher in patients with alopecia areata compared to the controls. The serum concentration of insulin and HOMA-IR correlated with the number of hair loss episodes (r = 0.300, p<0.05 and r = 0.322, p<0.05, respectively). Moreover, a positive correlation occurred between insulin, HOMA-IR, c-peptide and BMI (r = 0.436, p <0.05; r = 0.384, p<0.05 and r = 0.450, p<0.05, respectively). In conclusion, lipocalin-2 and insulin may serve as biomarkers for alopecia areata. Further studies are needed to evaluate the role of insulin as a prognostic factor in alopecia areata.