A nanofibre patch as a new treatment for psoriasis?

Beyond its innovative nanofibre structure, this patch is primarily intriguing due to the sequential nature of its active ingredient release, as evidenced in a test conducted in vitro.

• The fibres containing salicylic acid demonstrated a rapid release, with over 70% of the salicylic acid being released within the first hour. This effect, known as burst release, is due to the location of the salicylic acid in the outer layer of the fibres, which facilitates its immediate contact with the external environment. This property is particularly suited for its keratolytic role, aimed at quickly eliminating dead cells on the skin surface.

• On the other hand, hydrocortisone has demonstrated a gradual and sustained release. In the first hour, approximately 40% of the hydrocortisone was released, followed by a continuous diffusion reaching 80% after three days and 90% after a week. This delayed release can be attributed to the positioning of the hydrocortisone within an inner layer of the fibres, shielded by the outer layers. These layers act as a diffusion barrier, allowing for a gradual release of the hydrocortisone.

The sequential release of active ingredients allows for a more efficient and simplified management for the patient, with only a single daily application of the patch.

Furthermore, in order to verify that the active ingredients of the patch were properly absorbed by the skin, the researchers conducted skin permeation tests on samples of dorsal pig skin and compared the results to those obtained with "standard" creams containing 3% salicylic acid and 1% hydrocortisone. It was shown that the fibre patch allowed for greater penetration of hydrocortisone into the epidermis and dermis, estimated at 4.5% for each layer, compared to less than 1.5% for the standard cream. As for salicylic acid, the permeation of this active ingredient was similar between the patch and the ointment. This result is not surprising, however, as the released salicylic acid is supposed to remain primarily on the skin's surface and perform a keratolytic role.

However, this increase in the permeation of hydrocortisone into the various layers of the skin raises a significant question: is the risk of systemic side effects higher compared to creams? Although hydrocortisone is a common active ingredient in the therapeutic arsenal against psoriasis, increased absorption could heighten the frequency and intensity of adverse effects, particularly in cases of prolonged or repeated use. It would therefore be beneficial for additional studies to be conducted to assess these potential risks.

Finally, the anti-inflammatory effect of this patch was tested in vitro. For this, the nanofibres of the patch were co-cultured with human keratinocytes for 24 and 48 hours. The levels of IL-6, a pro-inflammatory cytokine involved in the pathogenesis of psoriasis, were measured before and after, and a significant decrease in this molecule was recorded over time. These results allow us to suppose that this patch could significantly alleviate skin inflammations.

This nanofibre patch could therefore have real potential in the treatment of psoriasis.

Furthermore, beyond psoriasis, this device has potential applications for other dermatoses, such as the eczema. The ability to modulate active ingredients and their release also opens up interesting prospects in the field of wound healing, by replicating environments conducive to skin regeneration. However, although the results are promising, several steps remain necessary before it can be made available to patients and clinical trials still need to be conducted to validate the effectiveness and safety of the patch on groups of patients suffering from psoriasis.

However, if this patch were indeed to become a reality, one might question its practicality, particularly for patients with multiple psoriasis plaques on their body. In addition to the potentially unsightly appearance this could create, this solution could be costly for these individuals as it would require the use of multiple patches. Another question arises regarding the size of the patches and their adaptability to psoriasis plaques of varying sizes and irregular shapes. Depending on the extent of the patients' condition, their practical use could be limited, particularly if multiple patches are needed to cover a single lesion. Furthermore, their compatibility with certain areas frequently affected by psoriasis, such as the scalp where plaques are often thick and difficult to reach, remains an open question.

Finally, the time required to release all the hydrocortisone, being several days, is not ideal. Considering that each patch will likely need to be changed after each shower, swim or workout, it is understandable that a portion of the hydrocortisone from the patches will be lost and will not penetrate the skin. A complete release of the hydrocortisone within eight hours of application would be optimal and would allow patients to apply the patch in the evening, before sleeping, and remove it the following morning.

This new treatment raises several questions that would need to be explored in the forthcoming optimisation studies planned by the researchers.