In older women with depression, blood levels of the immune peptide LL‑37 are higher than in non‑depressed peers, and this rise isn’t linked to overall body weight, muscle, or fat—except that more visceral (belly) fat might be tied to higher LL‑37. Overall body composition doesn’t seem to drive LL‑37 levels.

Antimicrobial peptides are components of the innate immune system. Cathelicidin LL-37 plays an important role in antimicrobial defense, exerts proinflammatory effect and strongly affects the immune system functioning. Our recent study revealed that serum concentration of LL-37 is increased in elderly women with depression. The aim of this study is to evaluate serum LL-37 levels in elderly women with depression and to compare them with non-depressed elderly women, matched for anthropometric and body composition parameters. Forty women with unipolar depression and 23 non-depressed women (age ≥60 years) were included into the study. Anthropometric measurements and biochemical analyzes were performed. Concentration of LL-37 in serum was assessed using ELISA method. Body composition was measured using two methods: bioimpedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA). There was a statistically significant difference (p =.038) in serum LL-37 level between patients with depression (3.55 ± 6.57 ng/mL) and control subjects (2.01 ± 3.88 ng/mL). Apart from visceral adipose tissue mass (%) in the depression group, we found no associations between serum LL-37 and analyzed anthropometric or body composition parameters. Results of this study indicate that with the exception of visceral adipose tissue, LL-37 serum levels are not affected by anthropometric or body composition parameters. The association between visceral adipose tissue and LL-37 may indicate that visceral fat could be responsible for the increased LL-37 production.