The study looked at how the natural peptide LL‑37, which is high in people with psoriasis, changes the signals immune cells send when they’re in a skin‑like environment. It found that LL‑37 can shift the mix of chemokines (immune‑messenger proteins) released by blood cells, and that psoriasis patients have different patterns of certain receptors on their T‑cells compared to healthy people. However, the work is basic research and does not give clear guidance on using LL‑37 for health or anti‑aging purposes.

Psoriasis is an autoimmune disease of the skin with keratinocyte hyperproliferation and increased skin homing of immune cells. LL-37 is an antimicrobial peptide present at a high level in psoriasis patients. It is thought to participate in the induction of psoriasis and is a potential autoantigen. This study explores the chemokine receptor expression of T cells in psoriasis patients in the context of LL-37 bioavailability in the skin. Thus, chemokines secreted by peripheral blood mononuclear cells (PBMCs), cultured in a psoriasis-mimicking Th1 or Th17 microenvironment, are evaluated in association with LL-37 secretion. The results show that the chemokine receptors CXCR3, CCR4 and CCR6 were expressed at different levels by T cells depending on their expression of the skin-homing and retention markers cutaneous lymphocyte antigen (CLA) and CD103, respectively. A higher proportion of T cells from psoriasis patients expressed CCR6 compared to those from healthy controls, whereas a lower proportion of psoriatic T cells expressed CXCR3^hi. PBMCs stimulated in Th1 and Th17 mimicking microenvironments altered their secretion of many immune biomarkers, further modulated by the addition of LL-37. Principal component analysis revealed that the secretion of chemokines from PBMCs after Th1 stimulation clustered away from the secretion of chemokines after Th17 stimulation. Stimulation of CXCR3^hi expressing CD4⁺ T cells revealed less secretory potential than their CXCR3^neg expressing CD4⁺ T cells. In summary, LL-37 demonstrated remarkable abilities in modulating the secretion of immune biomarkers by PBMCs, which may cause a change in the microenvironment in the skin in psoriasis.