Aberrant recruitment of leukocytes defines poor wound healing in patients with recessive dystrophic epidermolysis bullosa

Abstract

Background: Poorly healing wounds are one of the major complications in patients suffering from recessive dystrophic epidermolysis bullosa (RDEB). At present, there are no effective means to analyze changes in cellular and molecular networks occurring during RDEB wound progression to predict wound outcome and design betted wound management approaches. Objectives: To better define mechanisms influencing RDEB wound progression by evaluating changes in molecular and cellular networks. Methods: We developed a non-invasive approach for sampling and analysis of wound-associated constituents using wound-covering bandages. Cellular and molecular components from seventy-six samples collected from early, established and chronic RDEB wounds were evaluated by FACS-based immuno-phenotyping and ELISA. Results: Our cross-sectional analysis determined that progression of RDEB wounds to chronic state is associated with the accumulation (up to 90 %) of CD16 + CD66b + mature neutrophils, loss of CD11b + CD68 + macrophages, and a significant increase (up to 50 %) in a number of CD11c + CD80 + CD86 + activated professional antigen presenting cells (APC). It was also marked by changes in activated T cells populations including a reduction of CD45RO + peripheral memory T cells from 80 % to 30 % and an increase (up to 70 %) in CD45RA + effector T cells. Significantly higher levels of MMP9, VEGF-A and cathepsin G were also associated with advancing of wounds to poorly healing state. Conclusions: Our data demonstrated that wound-covering bandages are useful for a non-invasive sampling and analysis of wound-associated constituents and that transition to poorly healing wounds in RDEB patients as associated with distinct changes in leukocytic infiltrates, matrix-remodeling enzymes and pro-angiogenic factors at wound sites.

Immunological mechanisms underlying progression of chronic wounds in recessive dystrophic epidermolysis bullosa

“…Without macrophages, wound healing would not progress 18,31,32 . Our prior study showed that, in RDEB patients, the percentage of macrophages in wound bed‐associated leucocytes drops significantly in chronic wounds compared with early and established wounds 7 . An impaired macrophage response towards cutaneous bacterial infection has also been shown in DEB mice 12 .…”

“…Blister fluids of DEB and JEB patients contain increased levels of IL‐8 and matrix metalloproteinase 9 (MMP9), which is a granular protease in neutrophils 23,24 . Recently, we have also found that MMP9 and cathepsin G activity are upregulated in established and chronic RDEB wounds 7 . MMP9 and cathepsin G are the main granular proteases in neutrophils 20 and neutrophil‐derived proteases associated with chronic non‐healing wounds 21 .…”

“…The low percentage of macrophages in RDEB wounds 7 suggests an intrinsic, innate immune defect due to the absence or dysfunction of type VII collagen (Col7). Nyström et al (2018) support this hypothesis by showing that Col7 binds cochlin, the innate immune activator, in draining lymph nodes 12 .…”

“…In patients with recessive DEB (RDEB), in particular, continuous blistering, inflammation, relapsing infections and disturbed regeneration lead to painful, chronically inflamed often non‐healing wounds. Furthermore, colonization and invasion of wounds with pathogenic bacteria result in excessive inflammation and affect wound healing progression 1,7 . This makes RDEB patients prone to life‐threatening infections and sepsis, a leading cause of infant mortality 8,9 .…”

Pro‐inflammatory immunity supports fibrosis advancement in epidermolysis bullosa: intervention with Ang‐(1‐7)

“…Dysregulation of inflammatory events commonly underlies wound healing pathologies, from chronic wounds to fibrosis (Eming et al , 2017). RDEB can be considered a wound healing pathology, and indeed analyses of skin wounds, dressings, and sera from people with RDEB have revealed altered abundance and activity of immune cells and immune mediators, with some studies indicating wound type‐dependent changes (Nyström et al , 2015; Alexeev et al , 2017; Cianfarani et al , 2017; Fuentes et al , 2020; Phillips et al , 2020; Huitema et al , 2021). Rebalancing the inflammatory response downstream of chemically evoked tissue injury and inflammation can attenuate fibrosis progression in preclinical models (Jeljeli et al , 2019).…”