Honey is potentially effective in the treatment of atopic dermatitis: Clinical and mechanistic studies !!
Introduction: As manuka honey (MH) exhibits immunoregulatory and anti- staphylococcal activities, we aimed to investigate if it could be effective in the treatment of atopic dermatitis (AD).
Methods: Adult volunteers with bilateral AD lesions were asked to apply MH on
one site overnight for seven consecutive days and leave the contralateral site
untreated as possible. Three Item Severity score was used to evaluate the response.
Skin swabs were obtained from both sites before and after treatment to investigate
the presence of staphylococci and enterotoxin production. In addition, the ability of MH and its methanolic and hexane extracts to down regulate IL4-induced CCL26 protein release from HaCaT cells was evaluated by enzyme linkedimmunosorbent assay. Also, the ability of MH to modulate calcium ionophore-induced mast cell degranulation was assessed by enzyme immunoassay.
Results: In 14 patients, AD lesions significantly improved post MH treatment
versus pre-treatment as compared to control lesions. No significant changes in the skin staphylococci were observed after day 7, irrespective of honey treatment.
Consistent with the clinical observation, MH significantly down regulated IL4-
induced CCL26 release from HaCaT cells in a dose-dependent manner. This effect
was partially lost, though remained significant, when methanolic and hexane
extracts of MH were utilized. In addition, mast cell degranulation was significantly
inhibited following treatment with MH.
Conclusions: MH is potentially effective in the treatment of AD lesions based on
both clinical and cellular studies through different mechanisms. This needs to be
confirmed by randomized and controlled clinical trials.
Honey is a nutritional material that is traditionally known for
its medicinal properties. It has been used in this context in diverse communities for thousands of years and is still widely
popular. Recently, it has been shown that honey has broad- spectrum antimicrobial properties both in vivo and in vitro and has been demonstrated to promote wound healing. In particular, manuka honey (MH) that is mainly derived from Leptospermum scoparium, a shrub grown in New Zealand, was shown to interrupt cell division of Staphylococcus aureus, the bacterium most commonly responsible forwound infections. In addition, it was shown to inhibit leukocyte infiltration, cyclooxygenase 2, and inducible nitric oxide synthase expression as well as inflammation mediated through toll like receptor (TLR)1/TLR2 pathway.
On the other hand, it may elicit pro-inflammatory properties in the absence of active inflammation. Atopic dermatitis (AD) is a common chronic atopic inflammatory skin disease characterized by intermittent
episodes of intense pruritus and maculopapular rash. Its prevalence is 10–20% in children and 1–3% in adults and it is usually the first manifestation of a range of allergic diseases that include asthma and allergic rhinitis in a phenomenon known as the atopic march. Most of the immune cell types are involved in the pathogenesis of AD particularly,eosinophils, mast cells, lymphocytes, and macrophages.
Keratinocytes in the epidermis also play an integral role inthe pathogenesis of AD by interacting with various immune
cells and stimuli from the external environment. For
example, under the influence of IL4 from Th2 lymphocytes and macrophages, keratinocytes produce chemokine ligand
(CCL) 26 (eotaxin 3), which is a major chemoattractant of eosinophils to the site of inflammation. S. aureus colonizes the skin of 70–90% of patients with AD, in contrast to only 5% of normal population. This is due to a defect in skin barrier function, repeated scratching, and deficient cutaneous antimicrobial peptides. Consequently, S. aureus is the main cause of bacterial superinfections of AD lesions. In addition, this bacterium produces highly inflammatory exotoxins such as a, b, g, and d cytolysins as well
as several enterotoxins (SEA to SEE) that may act as superantigens and exacerbate the on-going inflammation. The management of AD remains challenging in many patients where symptoms are not resolved by the available medications, which could also cause various adverse effects. Some patients prefer natural remedies and have claimed overall improvement in their symptoms when they applied honey topically on AD lesions. However, there is no clear evidence in the literature to support these claims clinically or possibly mechanistically. Because of the immunoregulatory effects of MH and its anti-staphylococcal properties in addition to the anecdotal patients’ reports, we hypothesized that MH modulates the skin inflammation in AD.