In a recent study published within the journal PLOS One, researchers investigated the efficacy of lavender essential oils in suppressing atopic dermatitis (AD) using an AD cell line. They not only established the anti-AD advantages of Lavandula genus essential oils and its derivative, linalyl acetate, but they did so without the necessity for human clinical testing or animal trials. They further established the non-skin-sensitizing nature of the essential oil, highlighting its potential as a stand-alone or ointment-supplementing suppressor of AD-induced skin itchiness.

Study: Fragrant oil from lavender as an atopic dermatitis suppressant. Image Credit: PhotoStockPhoto / Shutterstock

What’s AD, what are its causes, and the way can we fight it?

Atopic dermatitis (AD) is a condition that causes dry, itchy, and inflamed skin, mostly occurring in young children. It’s characterised by eczemas that repeatedly exacerbate and is a growing concern in today’s world, leading to a considerable reduction in the standard of lifetime of patients affected by the condition. Reports estimate that 15-20% of all children and 1-3% of adults play host to the disease.

While the underlying causes of AD haven’t yet been pinpointed, a mix of genetic and environmental aspects is believed to contribute to the condition, with mutations within the filaggrin gene present in 20% of AD patients. The filaggrin gene is important for the right functioning of the epidermal barrier, with modifications to the gene facilitating antigen invasion, thereby producing inflammatory cytokines. Environmental aspects, including mites, pollen, and chemical air pollutants, exacerbate these cytokines, causing excessive immune response, physiologically presented as itchy skin, especially on the arms and behind patients’ knees.

Current treatments for AD consist of immunosuppressants and steroids. Unfortunately, these treatments are symptomatic, reducing the itchiness while leaving the condition untreated. Recent research has identified United States (US) Food and Drug Administration (FDA)-approved novel therapeutic agents corresponding to dupilumab, tralokinumab, and baricitinib, which aim to cure the pathogenic mechanisms of AD but remain expensive and inaccessible. Due to this fact, there stays a pressing need for cost-effective, natural, and simply accessible interventions able to controlling AD effectively.

Folk medicine has long postulated using lavender essential oils to treat itchy skin. Given the widespread accessibility of the oils (lavender oils are probably the most commonly distributed cosmetic additives globally) in perfumes and lotions, their relative cost-effectiveness, and their environmental ‘greenness,’ these oils may hold the important thing to treating AD and similar skin ailments.

Three most important Lavandula species are utilized in essential oil production – Lavandula angustifolia, L. spica, and L. stoechas. Of those, L. angustifolia accommodates the best concentrations of probably useful bioactive terpenes – linalyl acetate and linalool. Depending on the region and harvest season, these bioactives vary in concentration between 1.2-59.4% and 9.3-68.8%, respectively. Encouragingly, murine models have elucidated that each compounds can effectively inhibit edemas, inflammation, and cytokine production.

Lavandula angustifolia flowers. Image Credit: nnattalli / Shutterstock

“L. angustifolia essential oil is traditionally thought to have anti-inflammatory and wound-healing properties, which is used as a massage oil in aromatherapy. For a few years, the scientific basis for such use was unknown, but lately, along with its anti-inflammatory and wound healing effects, increasing evidence has supported the normal use of L. angustifolia essential oil, albeit inconclusively, for its antibacterial and analgesic effects.”

Concerning the study

In the current study, researchers developed a xenobiotic response (XRE) reporter assay (‘XRE-NLuc’) using the human immortalized keratinocyte cell line (HaCaT) to check the efficacy of L. angustifolia essential oils, linalyl acetate, and linalool on AD. The xenobiotic response represents the response of AD patients to air and UV pollutants and hence serves as a proxy for the environmental exposure of AD patients to exacerbating agents.

They further used an ARE reporter assay to research the degree of skin sensitization accompanying different concentrations of L. angustifolia or its terpene extracts. To guage gene expression levels of HaCaT utilized in each assays, copy DNA (cDNA) libraries were constructed and subjected to quantitative polymerase chain response (qPCR) analyses.

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in tandem with western blotting was used to detect and quantify protein expression by assayed HaCaT cells. Finally, flow cytometry assays were used to evaluate the cell viability and the treatment’s Stimulation Index (SI) versus control cells.

Study findings

Results from the study indicate that L. angustifolia essential oil, linalyl acetate, and linalool are all able to AD inhibition via fragrant hydrocarbon receptor (AhR) suppression. The AhR receptor is chargeable for triggering the AD cascade on exposure to environmental pollutants (primarily air and UV).

“Each linalyl acetate and linalool inhibited AD in a concentration-dependent manner with IC₅₀ values of 519 μM and >1000 μM, respectively, indicating that the previous was stronger.”

The tested components were further found to inhibit induced Artemin expression. Artemin is a neurotrophic factor (ARTN) that causes skin stretching, directly leading to increased skin sensitivity and itchiness.

“Linalyl acetate and linalool also decreased the induced Artemin expression with IC₅₀ values of three.6 and 194 μM, respectively, indicating that linalyl acetate exerted a stronger inhibitory effect.”

Together, these results highlight that lavender essential oils can effectively combat air pollution-induced AD. Body lotions containing essential lavender oils or their purified extracts may each form a barrier against air pollution exposure while soothing preexisting itchiness. Moreover, SDS-PAGE and western blotting experiments indicate that linalyl acetate intrinsically promotes AhR and ARNT protein degradation, further highlighting its ability to inhibit AD.

Encouragingly, results from the skin sensitization assays revealed that lavender oils and their major components either had neutral or negative skin-sensitization effects, confirming their safety during direct-contact application on human skin.

Conclusions

In the current study, researchers investigated the potential of lavender essential oils in stopping and treating AD. Their results revealed that the oils, especially linalyl acetate, effectively inhibited the AD mechanistic cascade while remaining protected for human use.

“Our results indicate that linalyl acetate in L. angustifolia essential oil is a significant contributor to AD inhibitory effects and lavender oils with high linalyl acetate contents can be effective for AD treatment, although other components in L. angustifolia essential oil, which we didn’t test, could be other contributors. The outcomes presented here could also be limited as a consequence of the oils and assays utilized in this study. Importantly, just like several other agents, their efficacy is very depending on the optimal concentration range. Due to this fact, we respectfully suggest that their use at higher concentrations may not end in the specified therapeutic outcomes.”