Molecular Insights Into the Effects of PLLA-SCA on Gene Expression and Collagen Synthesis in Human 3D Skin Models Containing Macrophages.

Injectable poly-L-lactic acid (PLLA-SCA) is used for the correction of shallow to deep nasolabial fold contour deficiencies, cheek wrinkles, and other facial wrinkles. In contrast to hyaluronan (HA) fillers, PLLA-SCA has a biostimulatory effect by activating resident fibroblasts to produce collagen, but the mechanisms are not known in detail at the molecular level. Therefore, our aim was to investigate the molecular effects of PLLA-SCA in a comprehensive in vitro study. Since PLLA-SCA-dependent collagen production in fibroblasts depends on the interaction with macrophages, we generated novel macrophage-containing 3D skin models. According to the clinical application, PLLA-SCA was injected once into the dermal equivalent of the 3D skin model. Histological analysis showed a significant increase in epidermal thickness in these models after 5 and 14 days. Gene expression profiling revealed an upregulation of integrins and laminins (e.g., LAMA3, ITGA6), which are essential components of the dermal-epidermal junction. In addition, we found an upregulation of cytokines and chemokines (TGFB2, CXCL6, IL1B) at day 14 after PLLA-SCA injection. Interestingly, immunohistochemical analyses exhibited a significantly stimulated collagen I production in our models. These effects might be attributed, at least in part, to the upregulation of IL1B and subsequently CXCL6, which stimulates collagen I synthesis in human dermal fibroblasts as we could demonstrate. Taken together, our data provide for the first time molecular insights into the biostimulatory effects of PLLA-SCA on collagen I production in novel human 3D skin models comprising macrophages. J Drugs Dermatol. 2024;23(4):7791.    doi:10.36849/JDD.7791.

Understanding the impact of risankizumab on keratinocyte-derived IL-23A in a novel organotypic 3D skin model containing IL-23A responsive and IL-17A producing γδ-T-cells.

PURPOSE: To study the effects of the anti-IL-23A antibody risankizumab on the IL-36γ/IL-23A/IL-17A signalling cascade we used a newly developed 3D skin model consisting of primary human keratinocytes, fibroblasts and γδ-T-cells. METHODS: In this in vitro study we developed new full-thickness 3D skin models containing normal human epidermal keratinocytes (NHEK), normal human dermal fibroblasts (NHDF) and IL-23A responsive and IL-17A producing γδ-T-cells. The effects of IL-36γ stimulation with and without risankizumab treatment on IL-23A and IL-17A expression were examined at the RNA and protein levels. RESULTS: In preliminary monolayer experiments stimulation of γδ-T-cells with IL-23A promoted the IL-17A expression that was inhibited after risankizumab treatment. Using 3D skin models containing γδ-T-cells, we found that stimulation with IL-36γ significantly increased not only IL-23A but also IL-17A expression. These effects were inhibited by concomitant treatment with risankizumab. CONCLUSIONS: Our results showed that blockade of IL-23A has inhibitory effects on the IL-36γ/IL-23A feedforward loop. Our newly developed 3D skin model containing IL-23A responsive and IL-17A producing γδ-T-cells enables molecular analysis of targeted therapies aimed at the IL-36γ/IL-23A/IL-17A signalling cascade in psoriasis.

Biological effect of laser-assisted scar healing (LASH) on standardized human three-dimensional wound healing skin models using fractional non-ablative 1540 nm Er:Glass or 1550 nm diode lasers.

PURPOSE: In postoperative wound healing after surgical operations or ablative laser treatments, recent studies suggest the timely use of non-ablative fractional laser treatments with the aim to improve wound healing and prevent pathological scar formation. However, the underlying molecular mechanisms are poorly understood. The aim of this study was to investigate the effects of laser-assisted scar healing (LASH) at the molecular level and to combine it with already established wound healing-promoting local treatments. METHODS: We irradiated full-thickness 3D skin models with a fractional ablative Er:YAG laser to set standardized lesions to the epidermal and upper dermal layer. Subsequently, LASH was induced by irradiating the models with either a fractional non-ablative 1540 nm Er:Glass or 1550 nm diode laser. In addition, we tested the combination of non-ablative fractional laser treatment and topical aftercare with a dexpanthenol-containing ointment (DCO). RESULTS: Histological analysis revealed that models irradiated with the 1540 nm Er:Glass or 1550 nm diode laser exhibited accelerated but not complete wound closure after 16 h. In contrast, additional topical posttreatment with DCO resulted in complete wound closure. At gene expression level, both non-ablative laser systems showed similar effects on epidermal differentiation and mild anti-inflammatory properties. The additional posttreatment with DCO enhanced the wound-healing effects of LASH, especially the upregulation of epidermal differentiation markers and anti-inflammatory cytokines at the gene expression level. CONCLUSION: This in vitro study deciphers the biological effects of LASH with a fractional non-ablative 1540 nm Er:Glass or a 1550 nm diode laser in 3D skin models. These data help to better understand the biological properties of the LASH technique and is important to optimize its application.