Oligomeric α-Synuclein induces skin degeneration in a reconstructed human epidermis model

Cell senescence may promote epidermal inflammation and degeneration, termed as inflammaging, which is accompanied by keratinocyte loss, resulting in fine lines of wrinkles. Recent findings showed that healthy elderly skin expresses age- and neuron-related amyloidogenic proteins, such as tau, β-Amyloid34, and α-synuclein (α-Syn), typically found in patients with neurodegenerative diseases. These proteins form toxic aggregates that trigger inflammatory signals. Herein, we investigated the impact of oligomeric α-Syn (Oα-Syn) on the neurosphere (NP) and the reconstructed human epidermis (RHE) 3D models. First, we found the expression of α-Syn, β-Amyloid, and amyloid precursor protein (APP) in the RHE. Second, we challenged the RHE and NP with Oα-Syn, which decreased RHE regeneration, measured by the percentage of cell proliferation and thickness of the stratum basale, but did not affect NP neurite outgrowth. Oα-Syn did not decrease the number of human neonatal epidermal keratinocytes (HEKn) but, as seen for the RHE, it also decreased the proliferation of HEKn. We confirmed that the oligomeric, and not the monomeric α-Syn species, accounted for the proliferation-decreasing effect. Oα-Syn also increased the NF-κB nuclear translocation in HEKn analyzed by nucleus/cytoplasm NF-κB fluorescence intensity. In addition, Oα-Syn triggered inflammation in the RHE, by increasing the mRNA levels of IL-1β and tumor necrosis factor-alpha (TNF-α), and the release of TNF-α in a time-dependent manner. These findings show that Oα-Syn does not affect neurite outgrowth but induces a decrease in keratinocyte proliferation along with epidermal inflammation. With our tridimensional models, we demonstrated that the neurodegenerative protein Oα-Syn also degenerates the epidermis, drawing attention to the need of target-based screening to prevent and treat the effects of skin aging.

The Anti-Ageing and Whitening Potential of a Cosmetic Serum Containing 3-O-ethyl-l-ascorbic Acid

Skin ageing has many manifestations such as wrinkles, dryness, hyperpigmentation, and uneven skin tone. Extrinsic and intrinsic factors, especially solar ultraviolet light (UVB), contribute to skin ageing; its main features are brown spots, alterations in melanin pigmentation, and a decrease in collagen and hyaluronic acid linked to oxidative stress. Several studies showed that topical products containing ingredients with antioxidant activity can reduce oxidative damage; to provide a maximum anti-ageing effect to the skin, topical products can combine various ingredients. C-SHOT SERUM contains a combination of two molecules with a proven anti-ageing activity: a high percentage (30%) of a more stable vitamin C derivative, 3-O-ethyl-l-ascorbic acid, and lactic acid (1%). The product showed a high biocompatibility, assessed through an MTT assay on keratinocytes and on Reconstructed Human Epidermis (RHE, SkinEthic); the anti-ageing activity was demonstrated on human dermal fibroblasts and keratinocytes by a statistically significant increase in collagen production and a reduction of a UVB-induced DNA damage marker (γ-H2AX histone), indicating DNA protection. Moreover, a depigmenting activity, shown by a highly significant decrease in melanin content on treated Reconstructed Human Pigmented Epidermis (RHPE), was assessed. According to the data of our study, the tested product contrasts the effect of skin ageing and irregular pigmentation due to the physiological decline of the skin.

Proniosomal Gel for Topical Delivery of Rutin: Preparation, Physicochemical Characterization and In Vitro Toxicological Profile Using 3D Reconstructed Human Epidermis Tissue and 2D Cells

Rutin (Rut) is a natural flavonol, well-known for its broad-spectrum of therapeutic effects, including antioxidant and antitumoral activities; still, it has a reduced clinical outcome due to its limited solubility in aqueous solutions. To overcome this drawback, this study proposes a novel formulation for rutin as a proniosomal gel for cutaneous applications. The gel was prepared by coacervation phase-separation method and complies with the standard requirements in terms of particle size (140.5 ± 2.56 nm), zeta potential (−27.33 ± 0.09 mV), encapsulation capacity (> 50%), pH (7.002 ± 0.18) and rheological properties. The results showed high biocompatibility of the gel on the 3D reconstructed human epidermis model characterized by increased viability of the cells and a lack of irritant and phototoxic potential. The evaluations on 2D cells confirm the preferential cytotoxic effect of Rut on melanoma cells (IC50 value = 8.601 µM, nuclear fragmentation) compared to normal keratinocytes. Our data suggest that the proniosomal gel is a promising drug carrier for Rut in the management and prevention of skin disorders.

Assessment of the Skin Barrier Function in the Reconstructed Human Epidermis using a Multimodal Approach at molecular, tissue and functional levels

Reconstructed human epidermis models are used as epidermis alternatives in skin researches. It is necessary to provide molecular and functional characterization in order to assess these models. Our aim is...