Marchand, L. | bioRxiv Science

bioRxiv2021

Transcutaneous penetration of a single-chain variable fragment (scFv) compared to a full-size antibody: potential tool for Atopic Dermatitis (AD) treatment

BackgroundCurrently, several biologics are used for the treatment of cutaneous pathologies such as atopic dermatitis (AD), psoriasis (PSO) or skin cancers. The main administration routes are subcutaneous and intravenous injections. However, little is known about antibody penetration through the skin. ObjectivesThe aim was to study the transcutaneous penetration of a reduced-size antibody as a single-chain variable fragment (scFv) compared to a whole antibody (Ab) and to determine its capacity to neutralize an inflammatory cytokine involved in AD such as human interleukin-4 (hIL-4). MethodsTranscutaneous penetration was evaluated by ex vivo studies on tape-stripped pig ear skin. Antibody visualization through the skin was measured by Raman microspectroscopy. In addition, hIL-4 neutralization was studied using two 2D models. First, embryonic alkaline phosphatase (SEAP) secretion by HEK-Blue IL-4/IL-13 cells, proportional to hIL-4 cells stimulation, was quantified by OD 620 nm measurement in presence or absence of an anti-hIL4 scFv or Ab. Then, normal human keratinocytes (NHKs) were stimulated with polyinosinic-polycytidylic acid (poly I:C) +/- hIL-4 and treated with anti-hIL4 scFv. Human Interleukin-8 (hIL-8) concentrations were determined in culture supernatants by ELISA. ResultsAfter 24h of application, analysis by Raman microspectroscopy showed that scFv penetrated into the upper dermis while Ab remained on the stratum corneum. In addition, the anti-hIL4 scFv showed better efficiency compared to Ab, with a neutralization percentage at 200 nM of 68% and 47%, respectively, in the HEK-Blue IL-4/IL-13 model. hIL-8 dosage in stimulated NHKs supernatants revealed that addition of scFv induced a dose-dependent hIL-4 neutralization. ConclusionsscFv penetrates through to the upper papillary dermis while Ab remains on the surface. The anti-hIL4 scFv neutralizes its target effectively in two 2D models suggesting its potential use as topical therapy for AD.

immunology↗

bioRxiv2020

Papillary And Reticular Fibroblasts Generate Distinct Microenvironments That Differentially Impact Angiogenesis

Papillary and reticular dermis show distinct extracellular matrix (ECM) and vascularization, and fibroblasts isolated from these compartments have different gene expression patterns and behaviour in vitro. However, due to lack of relevant models, the contribution of skin fibroblast sub-populations to vascularization remains unknown. We thus cultured human papillary and reticular fibroblasts as cell sheets. Differential transcriptomic analysis was performed by RNA sequencing to characterize their microenvironment. Bioinformatic analysis revealed that each fibroblast population expressed specific angiogenesis and matrisome gene expression signatures resulting in specific ECM that differed both in composition and structure. The impact of secreted and ECM-bound factors was then assessed using 3D angiogenesis assays. When co-cultivated with endothelial cells, the papillary and reticular microenvironments induced the formation of distinct capillary networks mimicking the characteristics of vasculature of native dermis subcompartments (vessel diameter and density, number of branch points). Whereas conditioned media of papillary fibroblasts displayed intrinsic high angiogenic potential, reticular ones only contributed to capillary formation induced by exogenous VEGF. These results show that skin fibroblast populations regulate angiogenesis via both secreted and ECM-bound factors. Our work emphasizes the importance of papillary and reticular fibroblasts, not only for modelling dermis microenvironment but also for its vascularization.

cell biology↗