Skin-protective biological activities of bio-fermented Aframomum angustifolium extract by a consortium of microorganisms.

Background: Aframomum sp. is a genus of plants in the Zingiberaceae family. It includes several species, some of which are used in cosmetics for their various properties, making them useful in skincare products, particularly for anti-aging, moisturizing, and brightening the skin. However, to date, there is no experimental evidence on its natural extracts obtained or modified using microorganisms (bio-fermentation) as an anti-aging agent. Objective: The present study aimed to evaluate the antiaging effect of a Bio-fermented Aframomum angustifolium (BAA) extract on 3D bioprinted skin equivalent. Methods: The consortium of microorganisms contained Komagataeibacter, Gluconobacter, Acetobacter, Saccharomyces, Torulaspora, Brettanomyces, Hanseniaspora, Leuconostoc, Lactobacillus, Schizosaccharomyces. It was developed on a media containing water, sugar, and infused black tea leaves. The seeds of Aframomum angustifolium previously grounded were mixed with the culture medium, and the ferments in growth; this fermentation step lasted 10 days. Then, the medium was collected and filtered (0.22 µm) to obtain the BAA extract. To enhance our comprehension of the impact of BAA extract on skin aging, we developed skin equivalents using bio-printing methods with the presence or absence of keratinocyte stem cells (KSC). These skin equivalents were derived from keratinocytes obtained from both a middle-aged donor, with and without KSC. Moreover, we examined the effects of treating the KSC-depleted skin equivalents with Bio-fermented Aframomum angustifolium (BAA) extract for 5 days. Skin equivalents containing KSC-depleted keratinocytes exhibited histological characteristics typical of aged skin and were compared to skin equivalents derived from young donors. Results: The BAA extract contained specific organic acids such as lactic, gluconic, succinic acid and polyphenols. KSC-depleted skin equivalents that were treated with BAA extract exhibited higher specular reflection, indicating better hydration of the stratum corneum, higher mitotic activity in the epidermis basal layer, improved dermal-epidermal connectivity, and increased rigidity of the dermal-epidermal junction compared to non-treated KSC-depleted equivalents. BAA extract treatments also resulted in changes at the dermis level, with an increase in total collagen and a decrease in global laxity, suggesting that this extract could help maintain youthful-looking skin. Conclusion: In summary, our findings indicated that BAA extract treatments have pleiotropic beneficial effects on skin equivalents and that the bio-fermentation provides new biological activities to this plant.

Human skin keratinocytes, melanocytes, and fibroblasts contain distinct circadian clock machineries.

Skin acts as a barrier between the environment and internal organs and performs functions that are critical for the preservation of body homeostasis. In mammals, a complex network of circadian clocks and oscillators adapts physiology and behavior to environmental changes by generating circadian rhythms. These rhythms are induced in the central pacemaker and peripheral tissues by similar transcriptional-translational feedback loops involving clock genes. In this work, we investigated the presence of functional oscillators in the human skin by studying kinetics of clock gene expression in epidermal and dermal cells originating from the same donor and compared their characteristics. Primary cultures of fibroblasts, keratinocytes, and melanocytes were established from an abdominal biopsy and expression of clock genes following dexamethasone synchronization was assessed by qPCR. An original mathematical method was developed to analyze simultaneously up to nine clock genes. By fitting the oscillations to a common period, the phase relationships of the genes could be determined accurately. We thereby show the presence of functional circadian machinery in each cell type. These clockworks display specific periods and phase relationships between clock genes, suggesting regulatory mechanisms that are particular to each cell type. Taken together, our data demonstrate that skin has a complex circadian organization. Oscillators are present not only in fibroblasts but also in epidermal keratinocytes and melanocytes and are likely to act in coordination to drive rhythmic functions within the skin.

Cell model of inflammation.

Chemical and physical stimuli trigger a cutaneous response by first inducing the main epidermal cells, keratinocytes, to produce specific mediators that are responsible for the initiation of skin inflammation. Activation modulates cell communication, namely leucocyte recruitment and blood-to-skin extravasation through the selective barrier of the vascular ECs (endothelial cells). In the present study, we describe an in vitro model which takes into account the various steps of human skin inflammation, from keratinocyte activation to the adhesion of leucocytes to dermal capillary ECs. Human adult keratinocytes were subjected to stress by exposure to UV irradiation or neuropeptides, then the conditioned culture medium was used to mimic the natural micro-environmental conditions for dermal ECs. A relevant in vitro model must include appropriate cells from the skin. This is shown in the present study by the selective reaction of dermal ECs compared with EC lines from distinct origins, in terms of leucocyte recruitment, sensitivity to stress and nature of the stress-induced secreted mediators. This simplified model is suitable for the screening of anti-inflammatory molecules whose activity requires the presence of various skin cells.