In a tiny study of 19 people with leg ulcers, the researchers found that higher levels of the natural peptide LL‑37 in the blood were tied to faster wound healing, while low vitamin D levels didn’t matter. This suggests LL‑37 could be a useful marker or treatment target for stubborn wounds, but the evidence is still early and limited to a specific ulcer type.

Human cathelicidin, LL-37, is small antimicrobial peptide, which reveals also some immunomodulatory and proangiogenic properties and, therefore, may promote wound healing. The expression of LL-37 is controlled by various factors, including vitamin D. Thus, any disturbances in vitamin D level may influence LL-37 production and, possibly, affect wound healing. Since deficiency of vitamin D was identified as a common problem in the population, this proof of concept study aimed to verify the relationship between serum levels of LL-37, vitamin D, and healing rate of venous leg ulcers. The study involved small group (n = 19) of patients with venous leg ulcers. Apart from non-venous ulcer aethiology, compression intolerance, active vein thrombosis, and wound infection, the exclusion criteria concerned also kidney insufficiency. The results of the analysis of wound healing rates were correlated with patients' serum levels of 25(OH) vitamin D and LL-37. In addition, serum levels of pro-inflammatory cytokines (IL-6, IL-8, and TNF) were analyzed. We have found strong association between serum concentrations of LL-37 and the healing rates in patients with leg ulcers. Despite the fact that 25(OH) vitamin D levels in all patients were below the normal range, they did not show any correlation with healing rates. Furthermore, no association was observed between serum levels of 25(OH) vitamin D and LL-37. No significant correlation between tested pro-inflammatory cytokines and healing rate, LL-37, or 25(OH) vitamin D levels was also observed. Regardless of small study group, our results suggest that the assessment of serum concentration of LL-37, but not 25-hydroxy vitamin D, may help in predicting the wound healing efficacy. Moreover, this assessment may be useful in pre-selection of patients, which could benefit from local treatment with exogenous LL-37.