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ORIGINAL RESEARCH
Honey is potentially effective in the treatment of atopic
dermatitis: Clinical and mechanistic studies
Abdullah A. Alangari
1
, Keith Morris
2
, Bashir A. Lwaleed
3
, Laurie Lau
4
, Ken Jones
2
,
Rose Cooper
2
, & Rowena Jenkins
2
1
Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
2
Department of Biomedical Sciences, Cardiff Metropolitan University, Cardiff, UK
3
Faculty of Health Sciences, University of Southampton, Southampton, UK
4
Faculty of Medicine, University of Southampton, Southampton, UK
Keywords
Atopic dermatitis, honey, keratinocytes,
manuka, mast cells
Correspondence
Abdullah A. Alangari, Department of
Pediatrics, College of Medicine, King Saud
University, P.O. Box 2925, Riyadh 11461, Saudi
Arabia.
Tel: þ966506287276;
Fax: þ96614679463;
E-mail: aangari@ksu.edu.sa
Funding information
This study was funded by the Deanship of
Scientific Research at King Saud University
through the research group project No.
RGP-VPP-190.
Received: 18 November 2016; Revised: 21
January 2017; Accepted: 23 January 2017
Final version published online 30 March 2017.
Immunity, Inflammation and Disease
2017; 5(2): 190–199
doi: 10.1002/iid3.153
Abstract
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 linked
immunosorbent 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.
Introduction
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 [1–3] and has been demonstrated to promote wound
healing [4]. 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, [5] the bacterium most commonly responsible for
wound infections. In addition, it was shown to inhibit
leukocyte infiltration, cyclooxygenase 2, and inducible nitric
oxide synthase expression [6] as well as inflammation
mediatedthrough toll like receptor (TLR)1/TLR2 pathway [7].
On the other hand, it may elicit pro-inflammatory properties
in the absence of active inflammation [8].
Atopic dermatitis (AD) is a common chronic atopic
inflammatory skin disease characterized by intermittent
190 © 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution
and reproduction in any medium, provided the original work is properly cited.
episodes of intense pruritus and maculopapular rash [9]. 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 [10]. 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 in
the pathogenesis of AD by interacting with various immune
cells and stimuli from the external environment [11]. 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 [12, 13].
S. aureus colonizesthe skin of 70–90% of patients with AD,
in contrast to only 5% of normal population [14, 15]. This is
due to a defect in skin barrier function, repeated scratching,
and deficient cutaneous antimicrobial peptides [16]. Conse-
quently, 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,anddcytolysins as well
as several enterotoxins (SEA to SEE) that may act as
superantigens and exacerbatethe on-going inflammation [17].
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 [18]. 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 theliterature 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.
Methods
Clinical study
A proof-of-concept, open-label, pilot study was conducted
to investigate possible effects of honey on AD lesions.
Information about the study was circulated via email to all
students and staff within Cardiff Metropolitan University
inviting them or their adult relatives and friends with AD
with bilateral similarly affected area to participate. Subjects
with severe extensive AD and those with other associated
skin pathology were excluded. All volunteers were provided
with an outline of the study and informed consent was given
prior to recruitment. Cardiff School of Health Sciences’
Research Ethics Committee at Cardiff Metropolitan Univer-
sity granted ethical approval.
The AD lesions were clinically scored using the Three
Item Severity score (TIS), which includes erythema,
edema/papulation, and excoriation. Each item is scored
on a scale from 0 to 3 based on severity, so the total score
could be from 0 to 9 [19, 20]. If the bilateral lesions were not
exactly of the same severity, the slightly more severe site was
chosen for honey application. Recruited volunteers were
provided with a 50 g tube of Medihoney
TM
(kindly provided
by Derma Sciences, UK), which is sterilized MH by g-
irradiation; sterile gauze and a Millipore tape. On day 0 they
were asked to apply a layer of honey over the treatment site at
night and to cover it with gauze and remove the covering and
wash the site in the morning. They were also asked to repeat
this process for seven consecutive days and to leave the
contralateral ‘‘control’’ site untreated unless their symptoms
became intolerable, when they were advised to use their
regular treatment including topical steroids or calcineurin
inhibitors. Application of moisturizers was permitted freely
on both sites. On day 7, the volunteers were re-evaluated by
taking the TIS score. Skin swabs are taken of both treated and
untreated sites on days 0 and 7.
Bacteriological studies
Each skin site involved in the study was swabbedwith a Sterilin
swab moistened in sterile PBS through a 2 2cmsquarecut
in a sterile acetate sheet held above the skin. The swab was
immediately plated onto Mannitol Salt Agar (MSA; Oxoid,
Cambridge, UK) and incubated at 378C for 24 h. Colony color
was noted, coagulase tested using Staphaurex test (Fisher
Scientific Ltd, Loughborough, UK) and the identity of isolated
colonies was determined with BBL
TM
crystal kits for gram
positive bacteria (Becton Dickinson, Oxford, UK). Oxacillin
susceptibility was determined using 5 mg discs (Oxoid) on
Columbia agar plates incubated at 308C for 24 h. Isolates were
stored at 808C on Protect beads (Technical Service
Consultants Ltd, Heywood, UK) until required.
Production of A, B, C, and D enterotoxins was determined
by Ridascreen R4101 (R-biopharm, Darmstadt, Germany)
according to the manufacturer’s instructions. Briefly, each
isolate was cultivated in 10 mL tryptone soy broth (TSB;
Oxoid, Cambridge, UK) with and without a pre-determined
sub-lethal concentration [21] of 5% (w/v) MH at 378C for
24 h. Bacteria were removed by centrifugation at 3500gfor
5 min at 108C, the supernatant was filtered using 0.2 mm
filter (Millipore, Watford, UK) and 100 mL was tested in the
kit, which could only indicate presence or absence of the
respective enterotoxin.
Cellular studies
Viability assay
HaCaT cell line is regarded as a reliable model of human
keratinocytes and has been used extensively to study various
A. A. Alangari et al. Honey in the treatment of atopic dermatitis
© 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd. 191
skin diseases. To determine the concentration of MH that will
not be cytotoxic to HaCat cells, CellTiter 96
1
AQ
ueous
one
solution cell proliferation assay was utilized (Promega, South-
ampton, UK) as per manufacturer’s instructions. Briefly,
HaCaTs were seeded in a 96-well microplate at 10
4
cells/well.
The following day, the cells were treated with different
concentrations of MH UMF 10þ(Comvita, Maidenhead,
UK). The honey was filter-sterilized using Durapore (PVDF)
membrane 0.22 mmGVsyringefilter(Millipore). The same
honey type was used in all HaCaT experiments. The supernatant
was decanted 24 h later and a 20 mL of MTS tetrazolium was
added to 100 mL of PBS in each well. Spectrophotometric
analysis of cell proliferation was determined at 490 nm using a
plate reader (TECAN
TM
,Weymouth,UK).
HaCaT cell line culture and stimulation
Cells were cultured using cap vented corning cell culture flasks
(Sigma–Aldrich, Gillingham, UK) in Dulbecco’s Modified Eagle
Medium (DMEM), (Thermo Fisher Scientific, Loughborough,
UK) supplemented with 10% fetal calf serum (FCS) v/v, 100 IU
penicillin and 0.1 mg/mL streptomycin mix (1%, v/v), and
2 mM glutamine (1%, v/v) (Sigma–Aldrich). At about 80%
confluence, the cells were detached with trypsin and seeded in
12-well plates at 0.5 10
6
cells/mL/well until they achieved 70–
80% confluence. The cells were then treated with 1% (w/v) MH.
IL4 (Thermo Fisher Scientific) 50 ng/mL was applied 2 h later.
Cytokines measurement
At 24-h post-treatment with IL4 the supernatant was
retrieved. CCL26 and IL8 concentrations were measured
using Quantikine ELISA system (R&D Systems, Abingdon,
UK) as per manufacturer’s instructions.
RT-PCR
RNA was extracted from HaCaT cells using Trizol
(Invitrogen, Loughborough, UK). RNA quantity and quality
was estimated using Nanodrop
TM
spectrophotometer.
mRNA was converted into cDNA using high capacity
cDNA reverse transcription kit (Applied Biosystems,
Loughborough, UK) and 4.5 mL of cDNA was used in
each 10 mL PCR reaction. Taqman PCR method was used
with denaturation at 958C for 5 min, followed by 34 cycles of
denaturation at 958C for 1 min, annealing at 658C for 1 min,
extension at 728C for 1 min, and a final elongation at
728C for 10 min. GAPDH was used as housekeeping gene.
Forward and reverse primers for CCL26, IL8, and GAPDH
were also obtained from Applied Biosystems. Relative gene
expression was determined using the standard DDCt
method.
Western blotting
Signal Transducer and Activator of Transcription 6 (STAT6)
phosphorylation was estimated by Western Blotting. Briefly,
HaCaT cells were cultured in 8-well plates at 1 10
6
cells/
well then next day were treated with or without honey and
2 h later treated with IL4. They were lysed 1 h post-treatment
with IL4 using RIPA buffer with protease and phosphatase
inhibitors cocktails (all from Thermo Fisher Scientific). The
cell lysate was kept in ice for 30 min then sonicated,
centrifuged and stored at 808C for later use. Total protein
was estimated in the samples using protein assay kit (Biorad,
Watford, UK) according to manufacturer’s recommenda-
tion. After sample preparation, NuPAGE 10% bis-tris gels
(Invitrogen) were loaded with 40 mg of protein per lane and
run with 165 volts constant voltage. The protein was
transferred to nitrocellulose membrane using iBlot system
(Invitrogen). The membrane was incubated with antibodies
(Cell Signaling, Hitchin, UK) to p-STAT6 (1:1000), STAT6
(1:1000), then b-actin (1:2000) dilutions. The membrane
was stripped after each development with Restore Plus
stripping buffer (Thermo Fisher Scientific). Goat F(ab’)
2
anti-rabbit IgG F(ab’)
2
was used as secondary antibody in p-
STAT6 blot at 1:2000, STAT6 at 1:10,000, and beta actin at
1:20,000 dilutions. Amersham ECL prime was used as
detection reagent and the blot was developed on Amersham
Hyperfilm ECL (Healthcare Life Sciences, Amersham, UK).
Methanol and hexane extracts preparation
Methanol or hexane were mixed with MH separately (1:1
w/v) and homogenized by vortexing. The mixture was
centrifuged at 3000gfor 15 min and the supernatant was
aspirated and blown to dryness under N
2
. The methanol
extract was in liquid form and the hexane extract was in solid
form that was dissolved in 10 mL DMSO (Sigma–Aldrich)
per 1 g of honey. Extracts were adjusted to original volume of
solvent used by adding DMEM and that was considered
100%.
Mast cell degranulation assay
LAD-2 human mast cell line was used to study mast cell
degranulation in vitro and its inhibition by Medihoney
TM
.
Cells were cultured in a serum-free medium (StemPro-34
SFM, Invitrogen), which was supplied complete with L-
glutamine, penicillin, streptomycin, and stem cell factor.
They were pre-treated with 0.5%, 1%, and 2% Medihoney
TM
for 20 min at 378C, 5% CO
2
in air then challenged with
calcium ionophore-A23187. The concentration of stimu-
lated histamine release was determined using an enzyme
immunoassay according to the manufacturer’s instructions
(Beckman Coulter, High Wycombe, UK).
Statistical analysis
Paired Student’s t-test was used to compare groups in the
clinical study. For experimental studies, one or two-way
ANOVA with Turkey’s multiple comparison tests or
Honey in the treatment of atopic dermatitis A. A. Alangari et al.
192 © 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd.
Student’s t-test were applied. Statistical analysis was
undertaken using GraphPad Prism 6.0.
Results
Clinical study
Twenty-six individuals volunteered for the study. After
screening, 10 individuals did not have AD or did not have
two similarly affected areas and were excluded. Sixteen
participants were recruited and two withdrew one to two
days following recruitment due to worsening symptoms.
Fourteen patients completed the study. Their mean age
(SD) was 33 10 years, eight were females. There was no
difference at baseline in the mean TIS score between
treatment and control sites. The mean TIS score of honey
treated lesions was significantly less post-treatment as
compared to pre-treatment with mean difference ¼2
points, 95%CI (2.75, 1.25), p<0.001 (Fig. 1), whereas
there was no significant difference in control lesions between
pre- and post-treatment scores with mean difference ¼0.7
points, 95%CI (1.71, 0.28), p¼0.15. Only two patients
reported using topical steroid on the control site because of
intolerable symptoms. Interestingly, a one year follow up of
volunteers by phone calls revealed that three of them
(numbers 2, 8, and 13) reported overall improvement of
their eczema without using MH after the study period.
Bacteriological studies
Staphylococci were isolated from 25 (89%) of the 28
volunteer sites sampled on recruitment to the study (day 0)
and from 21/28 (75%) sites on day 7 (Table 1). Honey
treatment did not change the skin bacterial flora. Entero-
toxin production in vitro was detected in only six isolates,
which were cultures of S. aureus isolated from participants 4,
6, 12, and 14 (Table 1). Enterotoxins B, C, and D were below
detectable levels when S. aurues isolated from the treated
sites of volunteers 12, 6, and 4, respectively, were each
cultivated with Medihoney
TM
. However, enterotoxin C and D
were unaffected in the strains recovered from the untreated
sites of participant 6 and 14, respectively. Levels of
enterotoxins A and E were not abolished by honey treatment
in vitro in any tested strain.
Cellular studies
Viability of HaCaTs treated with different concentrations of
MH
After 24 h of MH treatment, the maximum concentration of
honey tested that did not reduce HaCaT viability was 2.5%
(w/v; Fig. 2). There was, in fact, increased proliferation at this
concentration, which could be attributed to the sugar
content of honey. We chose in most of the following
experiments to work with 1% honey (w/v) to be consistent
with previous studies.
Effect of MH treatment on IL4-induced CCL26 secretion
To investigate whether MH could down regulate IL4-
induced CCL26 secretion by HaCat cells, HaCaTs were
treated with IL4 50 ng/mL 2 h after the application of 1%,
0.1%, or 0.01% honey. We found that honey could
significantly down regulate CCL26 secretion in a dose-
dependent manner (p<0.001; Fig. 3a).
CCL26 mRNA expression
IL4 up regulates CCL26 secretion by inducing its m-RNA
transcription. To investigate whether MH effect on CCL26
secretion is mediated through interruption of this process,
we performed RT-PCR. There was a trend of reduction of
IL4 induced CCL26 m-RNA expression after pre-treatment
with 1% honey as compared to no treatment or 0.1% honey
treatment. This, however, was not significant (p¼0.29,
Fig. 3b). GAPDH was used as house keeping gene. Similar
results were obtained with GUSB as house keeping gene
(data not shown).
Effect of MH treatment on IL4-induced IL8 secretion
Because of the diverse contents of MH, the generalizability
of the above effects on multiple cytokines was investigated.
IL8 protein levels in the supernatant fluid as well as
m-RNA expression from the samples of the above
experiment were assessed. IL4 significantly induced IL8
release (p<0.001) and m-RNA expression (p¼0.03).
Figure 1. Three Item Severity (TIS) score of MH treated and control sites
pre- and post-treatment. The mean TIS for sites treated with MH was
significantly lower than that prior to treatment. n.s, not significant.
A. A. Alangari et al. Honey in the treatment of atopic dermatitis
© 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd. 193
However, we could not observe any effect of honey on IL4-
induced IL8 at either the protein or m-RNA levels (Fig. 3c,
d).
Effect of MH treatment on IL4-induced
STAT6 phosphorylation
Since the only known pathway of CCL26 induction by IL4
involves phosphorylation of STAT6 transcription factor
[22, 23], the ability of MH to down regulate STAT6
phosphorylation was investigated. HaCaTs were treated with
IL4 (50 ng/mL) with or without pretreatment with incre-
mental concentrations of honey 2 h earlier (Fig. 4a,b).
Analysis of the p-STAT6/STAT6 densitometry ratio did not
reveal any significant down regulation of IL4-induced
STAT6 phosphorylation following treatment with MH
(p¼0.78), although there was a small trend of decrement
with 1% honey treatment.
Effects of methanol and hexane honey extracts on
IL4-induced CCL26
To investigate which components of MH caused its effect
on CCL26 release from HaCaTs, we prepared methanol
and hexane extracts of whole MH. Methanol is a very polar
solvent with polarity index of 5.1% and 100% water
solubility, while hexane is a nonpolar solvent with polarity
index of 0.1% and 0.001% water solubility. Both 1% (w/v)
methanol and 1% (w/v) hexane extracts were able to
significantly down regulate IL4-induced CCL26 release
from HaCaTs, but significantly less than whole honey
(Fig. 5).
Table 1. Effect of honey treatment on cultured staphylococci from the patients’skin.
Volunteer
number
Site
tested
Staphylococci
recovered on Day 0
Staphylococci
recovered on Day 7
Enterotoxin detected
without honey
Enterotoxin detected in the presence of
5% (w/v) honey
2 Untreated S. haemolyticus S. haemolyticus
2 Treated S. haemolyticus S. saprophyticus
3 Untreated S. haemolyticus S. haemolyticus
3 Treated S. haemolyticus S. epidermidis
4 Untreated S. aureus A, E A, E
4 Treated S. aureus S. aureus A, D, E A, E
5 Untreated S. aureus
5 Treated S. aureus S. aureus
6 Untreated S. aureus CC
6 Treated S. aureus S. aureus C
7 Untreated S. simulans
7 Treated S. haemolyticus
8 Untreated S. haemolyticus S. haemolyticus
S. epidermidis
8 Treated S.saprophyticus
S. intermedius
9 Untreated S. aureus S. aureus
9 Treated S. aureus S. haemolyticus
10 Untreated S. kloosii
10 Treated No isolate to test No isolate to test
12 Untreated S. aureus S. aureus
12 Treated S. aureus (MRSA) S. aureus B
13 Untreated S. aureus S. aureus
13 Treated S. aureus S. aureus
14 Untreated S. haemolyticus S. aureus
S. capitis
14 Treated S. aureus S. aureus A, D, E A, D, E
S. haemolyticus S. auricularis
15 Untreated S. aureus S. aureus
15 Treated S. aureus S. aureus
S. capitis
16 Untreated S. aureus S. aureus
S. haemolyticus S. capitis
16 Treated S. aureus S. aureus
S. capitis
Honey treatment in vitro of the isolated S. aureus.
Honey in the treatment of atopic dermatitis A. A. Alangari et al.
194 © 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd.
Effect of honey treatment on mast cells degranulation
Pre-treatment of LAD2 cells with Medihoney
TM
lead to a
dose-dependent inhibition of histamine release following
calcium ionophore-A23187 stimulation (Fig. 6).
Discussion
We herein report a number of novel findings: a pilot clinical
study suggesting the efficacy of MH in the treatment of AD as
well as mechanistic data that support this clinical finding
including down regulation of IL4-induced CCL26 release
from keratinocytes and inhibition of mast cells degranula-
tion. We have also shown that the effect of honey is likely to
be mediated by multiple components of different physical
and chemical properties.
CCL26 plays a key role in the pathogenesis and severity of
AD [24, 25] as well as other conditions were eosinophils are a
major contributor such as asthma [26] and eosinophilic
esophagitis [27]. It is more potent than eotaxin1 (CCL11)
and eotaxin2 (CCL24) in attracting eosinophils [28].
Chemokine receptor (CCR)3 is a common receptor to all
three chemokines [29], its expression is up regulated in AD
lesions [30], and its blockade by monoclonal antibodies
inhibits eosinophils recruitment [31]. CCR3 is also ex-
pressed on basophils [32], mast cells [33], and activated Th2
cells [34]. Therefore, honey’s significant down regulation of
IL4-induced CCL26 release by keratinocytes could explain,
at least partly, our clinical findings. However, we could not
Figure 2. HaCaT cells viability after treatment with different concen-
trations of honey (w/v) using MTS assay. Y-axis indicates absorbance
reading. Bars represent the Mean SD. (n¼3). H, honey.
Figure 3. Effect of 1% honey pre-treatment of HaCaTs on (a) IL4-induced CCL26 protein release, and (b) m-RNA expression (GAPDH was used as house
keeping gene); (c) IL4-induced IL8 protein release, and (d) m-RNA expression (GAPDH was used as house keeping gene). Bars represent the Mean SD.
(n¼3). H, honey; n.s, not significant.
A. A. Alangari et al. Honey in the treatment of atopic dermatitis
© 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd. 195
show significant inhibition of STAT6 phosphorylation nor
could we able to show significant down regulation of CCL26
mRNA expression by MH following IL4 stimulation of
HaCaTs. This suggests that MH may exhibit its effects
primarily at CCL26 translational or post-translational levels,
and requires further study. Moreover, as methanolic and, to
a lesser extent, hexane extracts of MH retain some of the
activity of whole MH; it is likely that the effect of whole MH
is the sum of several of its multiple constituents. These
components possibly include polyphenolic compounds [35]
that we have found to exhibit anti-inflammatory effects
within MH methanolic extract (Wythecome et al., manu-
script under revision) and other lipid-soluble compounds
yet to be defined. For example, thiazolidinediones such as
troglitazone and rosiglitazone, which are peroxisome
proliferator-activated receptor g(PPARg) agonists and
structurally similar to some flavonoids found within MH,
have been shown to reduce IL4-induced eotaxin release dose
dependently, though via an unknown mechanism [36].
IL4 can also induce IL8 release from epithelial cells
[37, 38]. This effect is possibly mediated through p38
mitogen-activated protein kinase (MAPK), extracellular
signal-regulated kinase (ERK) pathway [39], rather than
STAT6 pathway [40]. MH did not modulate IL4-induced
IL8 release at the protein or mRNA levels. These findings
suggest that even with the large diversity of MH components,
its overall effects seem to be targeted toward certain
pathways.
Mast cells are found in increasing numbers in the
epidermis and dermis of patients with AD [41]. They
contribute to the signs and symptoms of the disease through
the release of mediators such as histamine from granules
causing itching, local redness, and edema [42] as well as
disturbing skin barrier integrity [43]. The dose-dependent
inhibition of histamine release by MH could partly explain
its clinical effects. However, its mechanism remains to be
elucidated.
Treatment with MH did not alter the skin culture results
of Staphylococci, but we observed in vitro inhibition of some
enterotoxins release namely, SEB, SEC, and SED from
cultured S. aureus that were obtained from three different
subjects. However, this inhibition did not correlate with the
clinical improvement in those particular subjects and was
not consistent in cases of SEC and SED. Nevertheless, this
needs further study. Recently it has been shown in
methicillin-resistant S. aurues (MRSA) that virulence genes
were down-regulated in vitro following exposure to MH,
with the greatest effect on sec3, a gene that codes for
SEC [44].
Our studies have some limitations. The patient number in
the clinical study is small and the scoring system applied,
although validated and correlates with more complex and
Figure 4. (a) Western Blotting showing no visible effect of pretreat-
ment of HaCaTs with 1% honey on IL4-induced STAT6 phosphory-
lation. (b) Densitometry analysis of p-STAT6/STAT6 ratio. Bars
represent the Mean SD. (n¼3). M, medium; H, honey; n.s, not
significant.
Figure 5. Effect of pre-treatment with 1% honey, 1% honey methanol
extract, and 1% honey hexane extract on IL4-induced CCL26 release
from HaCaTs. Bars represent the Mean SD. (n¼3). H, honey.
Honey in the treatment of atopic dermatitis A. A. Alangari et al.
196 © 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd.
widely used scores [19, 20], is not the gold standard of AD
clinical assessment, but is useful in evaluating specific lesions
rather than global response. It could also be argued that not
covering the control site may have had influenced the
outcome through patients’ scratching. However, the treated
site was only covered overnight. In addition, participants
had the liberty to treat the control site with their
conventional treatment at any time if they feel their
symptoms were intolerable and covering the control site
would have prevented them from doing so. Moreover, the
cover of the honey treated site was light and would not have
prevented participants from itching. In addition, the
mechanism by which MH inhibits IL4-induced CCL26
release form keratinocytes is still unclear. It was not also
possible to decipher the active ingredients in MH related to
our findings.
In conclusion, honey is a very complex material with
potential therapeutic value in the treatment of AD. Future
research should aim to investigate whether similar effects can
be reproduced with other honey types. Producing more
practical form of honey to use topically on the skin should
hasten clinical investigations. In addition, these findings
should open the door to the potential role of honey in the
treatment of other atopic conditions like asthma or allergic
rhinitis.
Acknowledgments
We are grateful to Dr. Andrew Thomas, Dr. Manindar
Aluwhalia, and Dr. Neil Rushmere for their helpful
discussions and provision of some reagents and to Prof.
Raif Geha for his critical review of this manuscript. This
study was funded by the Deanship of Scientific Research at
King Saud University through the research group project
No. RGP-VPP-190. The funder was not involved in the
conduct of research or article preparation.
Conflict of Interest
R. Cooper received consultation fees, sponsorship to attend
scientific meetings, and remuneration for presentations
from Derma Sciences Inc. and Comvita, UK. Other authors
have nothing to disclose in relation to this manuscript.
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