This means that the skin overproduces certain lipids in a failed attempt to repair its own barrier.
The study, conducted by researchers from Meyer Bio-Medicine Co and Shandong University suggested that the cosmetics industry may need to rethink its approach to treating dry skin.
The research team used advanced non-invasive technologies to map the molecular landscape of the skin, with their findings providing a multi-dimensional look at how skin hydration interacts with the skin’s physical structure and its internal chemical factory.
When it comes to skin care and ingredient sectors, the study shifts the focus from simple lipid supplementation to the precise modulation of lipid metabolic networks.
Molecular architecture of hydration
The researchers enrolled 60 healthy Chinese women between the ages of 30 and 55 for the study. To ensure a clear comparison, they divided the participants into two distinct groups based on their Corneometer readings.
The low-hydration group consisted of 11 women with moisture scores below 40 units, while the high-hydration group included 19 women with scores exceeding 70 units.
The team utilised a sophisticated suite of tools to look beneath the surface. This included confocal Raman spectroscopy to measure chemical constituents at specific depths and multiphoton laser tomography to assess dermal ageing. They also employed untargeted lipidomics to identify every single lipid species present in the stratum corneum.
The results showed a clear physical difference between the groups. The high-hydration group had a significantly thicker stratum corneum, measuring an average of 14.63 micrometres compared to the 12.43 micrometres found in the low-hydration group.
Furthermore, skin moisture levels were positively linked to the presence of ceramides and lactate, a key component of the skin’s natural moisturising factors.
Interestingly, the study found no significant link between hydration levels and common ageing signs like wrinkles, skin colour, or elasticity in this specific cohort.
The paradox of lipid upregulation in dry skin
One of the most surprising findings of the study was the discovery of 83 differential lipids that were more abundant in dry skin than in hydrated skin. This contradicts the traditional industry narrative that dry skin is simply “missing” the oils it needs.
All 83 of these lipids showed a significant upward trend in the low-hydration group, in which the researchers believed to be a compensatory response.
When the skin barrier is compromised and begins to lose water, the body’s keratinocytes go into overdrive, ramping up lipid synthesis to try to plug the leaks. However, this emergency response often results in an imbalanced mixture of lipids that cannot form the tight, organised structures required for a healthy barrier.
Ten specific lipids showed a particularly strong negative correlation with hydration levels. Nine of these were ceramides, including subtypes such as Cer-AP, Cer-AS, and Cer-NS.
The researchers noted that these specific ceramides could change the physical state of the skin barrier. For example, an excess of certain “bent” ceramides can prevent the skin’s lipid matrix from forming a tight, protective seal, leading to even more water loss.
Shifting the focus to metabolic balance
The study highlighted that the ratio of lipids was far more important than the total amount.
In the high-hydration group, the lipids were balanced in a way that supported a “tight orthorhombic” packing of the skin cells. In the low-hydration group, the imbalance in ceramide subtypes likely pushed the skin into a “looser hexagonal” lattice, which was much more permeable to water.
The researchers explained that this dysregulation represented a core molecular feature of dry skin that goes beyond a lack of moisture and points to breakdown in the skin’s internal metabolic signalling.
The lipidomic analysis revealed that these changes were primarily linked to sphingolipid and triacylglycerol metabolic pathways.
This suggested that the future of moisturising products could lie in metabolism-targeted therapies. Rather than just adding a generic blend of ceramides to a cream, the goal should be to restore the specific proportions of lipid subtypes.
The researchers suggested that bioactive agents capable of regulating key enzymatic activities could be more effective at fundamentally restoring skin barrier homeostasis than traditional occlusive moisturisers.
Current limitations and future implications
The findings provided a theoretical foundation for a new generation of skin care. By identifying specific biomarkers associated with low hydration, such as the 10 lipids mentioned in the study, companies can develop more targeted diagnostic tools and personalised treatments.
The study also reinforced the value of using non-invasive technologies like Raman spectroscopy in clinical trials to get a more accurate picture of product efficacy at the molecular level.
Nevertheless, the research team acknowledged some study limitations. The sample size was relatively small, with just 30 participants analysed in the final comparison. Additionally, the study did not include measurements of transepidermal water loss, which is often considered the gold standard for assessing barrier function.
The authors concluded: “These findings offer a novel systems biology perspective on skin barrier function and hydration mechanisms. Our work not only deepens the understanding of the physiological basis of skin dryness, but also provides a critical theoretical foundation and potential biomarkers for developing innovative skin care strategies that target the lipid metabolic network to alleviate skin dryness and delay ageing.”
Source: Cosmetics
“Systemic Lipid Dysregulation in Low-Hydration Skin: A Multi-Dimensional Analysis”
https://doi.org/10.3390/cosmetics13010004
Authors: Fan Yumei, et al.
