Delayed inflammatory resolution and TGF-beta expressing Tregs are associated with healing outcomes in paediatric burns.

The aim of this study was to identify immune cells and inflammatory mediators associated with delayed wound healing in paediatric burn patients. Peripheral blood mononuclear cells (PBMCs) were isolated from 30 paediatric participants: 10 healthy age- and sex-matched controls, 10 burn patients whose wounds healed within 21 days (normal healing), and 10 patients with healing times exceeding 21 days (delayed healing). Flow cytometry was used to quantify immune cell subsets and intracellular cytokine expression, and plasma cytokines were measured via multiplex immunoassay. There were no significant differences in the proportions of major immune cell subsets-including CD4⁺ T-helper cells, CD8⁺ cytotoxic T cells, monocytes, and macrophages-between the groups. However, delayed healing patients exhibited significantly higher frequencies of CCR6⁺ cells and elevated expression of pro-inflammatory cytokines IL-17 and IL-23 in γδ T cells, NKT-like cells, and regulatory T cells (Tregs). Plasma concentrations of IL-33, IL-23, TNF-α, and MCP-1 were also significantly increased in the delayed healing group (p < 0.05). In contrast, patients with normal healing displayed higher proportions of Tregs expressing the anti-inflammatory cytokine TGF-β. These findings suggest that delayed healing in paediatric burn patients may be associated with a persistent systemic pro-inflammatory immune profile, marked by elevated CCR6 expression and IL-17/IL-23 axis activation. This unresolved inflammation could contribute to chronic immune dysregulation and may underlie the long-term comorbidities observed in this population. Targeting these inflammatory pathways may offer novel therapeutic strategies to improve wound healing outcomes in paediatric burns.