Withaferin-A Can Be Used to Modulate the Keratin Network of Intermediate Filaments in Human Epidermal Keratinocytes

Viaminate ameliorates Propionibacterium acnes-induced acne via inhibition of the TLR2/NF-κB and MAPK pathways in rats

Viaminate, a retinoic acid derivative developed in China, has been clinically used for acne treatment to regulate and control keratinocyte cell differentiation and proliferation, inhibit keratinization, reduce sebum secretion, and regulate immune and anti-inflammatory functions; however, its potential molecular mechanism has not yet been elucidated. Therefore, we induced ear acne in rats using Propionibacterium acnes and sebum application. Symptoms of ear redness, epidermal thickening, inflammatory reaction, keratin overproduction, subcutaneous oil, and triglyceride (TG) accumulation improved significantly in acne model rats treated with viaminate for 30 days. Transcriptome analysis of rat skin tissues suggested that viaminate had significant regulatory effects on fatty acid metabolism and cellular keratinization pathways. Molecular target prediction suggested that toll-like receptor 2 (TLR2) may be a key target of viaminate's therapeutic mechanism. Western blotting results confirmed that viaminate inhibited the TLR2 and its downstream pathways, nuclear factor-kappa B (NF-κB) [NF-κB inhibitor alpha (IκBα)/NF-κB-p65] and mitogen-activated protein kinases (MAPKs) [MAPK p38/c-Jun N-terminal kinase (JNK)/extracellular regulated kinase 1/2 (ERK1/2)] in acne vulgaris rats. In vitro studies revealed that viaminate treatment attenuated P. acnes proliferation and P. acnes-induced inflammatory response in human keratinocytes and has an inhibitory effect on the activation of NF-κB and MAPKs, while overexpression of TLR2 attenuated these effects. In conclusion, viaminate ameliorates P. acnes-induced acne by inhibiting the proliferation and inflammatory response of keratinocytes, ascribed to the deactivation of the TLR2-mediated NF-κB and MAPK pathways.

The Mechanical Interplay Between Differentiating Mesenchymal Stem Cells and Gelatin-Based Substrates Measured by Atomic Force Microscopy

Traditional methods to assess hMSCs differentiation typically require long-term culture until cells show marked expression of histological markers such as lipid accumulation inside the cytoplasm or mineral deposition onto the surrounding matrix. In parallel, stem cell differentiation has been shown to involve the reorganization of the cell’s cytoskeleton shortly after differentiation induced by soluble factors. Given the cytoskeleton’s role in determining the mechanical properties of adherent cells, the mechanical characterization of stem cells could thus be a potential tool to assess cellular commitment at much earlier time points. In this study, we measured the mechanical properties of hMSCs cultured on soft gelatin-based hydrogels at multiple time points after differentiation induction toward adipogenic or osteogenic lineages. Our results show that the mechanical properties of cells (stiffness and viscosity) and the organization of the actin cytoskeleton are highly correlated with lineage commitment. Most importantly, we also found that the mechanical properties and the topography of the gelatin substrate in the vicinity of the cells are also altered as differentiation progresses toward the osteogenic lineage, but not on the adipogenic case. Together, these results confirm the biophysical changes associated with stem cell differentiation and suggest a mechanical interplay between the differentiating stem cells and their surrounding extracellular matrix.