Dandruff is a skin condition that affects the scalp of up to half the world’s population, it is characterised by an itchy, flaky scalp and is associated with colonisation of the skin by Malassezia spp. Management of this condition is typically via antifungal therapies, however the precise role of microbes in the aggravation of the condition are incompletely characterised. Here, a combination of 454 sequencing and qPCR techniques were used to compare the scalp microbiota of dandruff and non-dandruff affected Chinese subjects. Based on 454 sequencing of the scalp microbiome, the two most abundant bacterial genera found on the scalp surface were Cutibacterium (formerly Propionibacterium) and Staphylococcus, while Malassezia was the main fungal inhabitant. Quantitative PCR (qPCR) analysis of four scalp taxa (M. restricta, M. globosa, C. acnes and Staphylococcus spp.) believed to represent the bulk of the overall population was additionally carried out. Metataxonomic and qPCR analyses were performed on healthy and lesional buffer scrub samples to facilitate assessment of whether the scalp condition is associated with differential microbial communities on the sampled skin. Dandruff was associated with greater frequencies of M. restricta and Staphylococcus spp. compared with the healthy population (p<0.05). Analysis also revealed the presence of an unclassified fungal taxon that could represent a novel Malassezia species. 18 12 2019 14 12 e0225796 e0225796 7 1 2020 © 2019 Grimshaw et al This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Dandruff is a skin condition that affects the scalp of up to half the world’s population, it is characterised by an itchy, flaky scalp and is associated with colonisation of the skin by Malassezia spp. Management of this condition is typically via antifungal therapies, however the precise role of microbes in the aggravation of the condition are incompletely characterised. Metataxonomic and qPCR analyses were performed on healthy and lesional buffer scrub samples to facilitate assessment of whether the scalp condition is associated with differential microbial communities on the sampled skin. Dandruff was associated with greater frequencies of M . restricta and Staphylococcus spp. compared with the healthy population (p<0.05). Analysis also revealed the presence of an unclassified fungal taxon that could represent a novel Malassezia species. status released display-pdf yes is-olf no is-manuscript no is-preprint no is-journal-matter no is-scanned no is-retracted no Received 2019 Aug 5; Accepted 2019 Nov 12; Collection date 2019. Introduction It is well accepted that the human body’s resident microbiota play a critical role in the maintenance of human health with numerous studies demonstrating that alterations in microbial community composition are associated with disease states as diverse as irritable bowel syndrome, acne, periodontal diseases and atopic dermatitis [ 1 – 3 ]. The proposed microbiome-mediated cosmetic condition dandruff is a scalp condition characterised by excessive flaking of skin, often accompanied by dryness and itch [ 4 ]. Over half of the world’s population will suffer from dandruff during their lifetime [ 5 ]. In total 18 members of the genus [ 12 – 15 ] are described, most of these have been examined in-depth via genus wide comparative genomics by Wu et al [ 12 ]. The association between altered relative and absolute abundance of Malassezia spp. and scalp health was shown in multiple studies [ 16 – 18 ]. These fungi are considered commensal members of the human skin microbiome [ 19 ], where they are predominately represented by M . restricta and M . globosa . These and other microbial species were found to be associated with dandruff and other human skin conditions [ 20 , 21 ]. Seasonality may also play a contributory environmental role, with the dandruff condition being exacerbated during the winter months [ 4 ]. Subjects were excluded from the study if they had used anti-dandruff shampoo containing for example, Zinc Pyrithione (ZPT), selenium sulfide or ketoconazole within the last 6 months, were taking anti-inflammatory medication, or had suffered or were currently suffering from any skin condition on head and / or neck (e.g. eczema, psoriasis). Scalp condition was evaluated using a visual assessment method, resulting in a numerical score, the total weighted head score, or TWHS [ 35 ]. This is a whole head assessment of scalp condition based on evidence of dryness/dandruff of the scalp, loose flakes in the hair, and scalp erythema. However, the data presented here suggests that localised microbial dysbiosis is occurring at lesional sites only and is consistent with previous host response analysis showing that human transcriptomics response in the dandruff condition is also localised to lesional sites [ 64 ]. Fig 8 Non-metric Multi-Dimensional Scaling Bray Curtis analysis of bacterial communities at genus (a) and OTU (b) level at differentially graded scalp sites. Beta Diversity analysis of bacterial communities shows significant differences (p>0.01), at both genus and OTU level, between lesional sites on a dandruff scalp (Dandruff_C) and all other sites tested. As demonstrated previously and irrespective of scalp condition, the major component of the fungal mycobiome of both healthy and dandruff scalps is Malassezia restricta . The results presented here are in agreement with a long association of the dandruff condition with an alteration in the abundance of M . restricta . While no differences were seen in the relative abundance of M . restricta and M . globosa , significant differences in absolute abundance (qPCR) for both Malassezia species were evident when comparing lesional and non-lesional sites on healthy and dandruff scalps.

Dandruff is characterized by a flaky, pruritic scalp and affects up to half the world's population post-puberty. The aetiology of dandruff is multifactorial, influenced by Malassezia, sebum production and individual susceptibility. The commensal yeast Malassezia is a strong contributory factor to dandruff formation, but the presence of Malassezia on healthy scalps indicates that Malassezia alone is not a sufficient cause. A healthy stratum corneum (SC) forms a protective barrier to prevent water loss and maintain hydration of the scalp. It also protects against external insults such as microorganisms, including Malassezia, and toxic materials. Severe or chronic barrier damage can impair proper hydration, leading to atypical epidermal proliferation, keratinocyte differentiation and SC maturation, which may underlie some dandruff symptoms. The depleted and disorganized structural lipids of the dandruff SC are consistent with the weakened barrier indicated by elevated transepidermal water loss. Further evidence of a weakened barrier in dandruff includes subclinical inflammation and higher susceptibility to topical irritants. We are proposing that disruption of the SC of the scalp may facilitate dandruff generation, in part by affecting susceptibility to metabolites from Malassezia. Treatment of dandruff with cosmetic products to directly improve SC integrity while providing effective antifungal activity may thus be beneficial. 1 ), and is often accompanied by itch. The condition tends to develop post-puberty and is restricted to the scalp with the presence of terminal hair. The severity of dandruff can range from mild scale formation similar to dry skin to seborrhoeic dermatitis (SD) [ 2 , 3 ]. Although often characterized as a more severe form of dandruff, there is currently no clear agreement on the symptomatic and aetiological links between these two conditions, leading to confusion between SD and dandruff [ 4 – 6 ]. Figure 1 (a) Healthy Scalp (dandruff free). (b) Dandruff scalp showing characteristic flaking. Dandruff severity would be for this image is Grade c–d (see Table I ). Understanding the biophysical, biochemical and ultrastructural changes in the properties of the SC that occur with dandruff may further elucidate the mechanisms of dandruff initiation or susceptibility. In this review, we will discuss the recent evidence for the impact of individual predisposition, Malassezia colonization and sebum production on the development of dandruff. In particular, we will focus on the importance of SC barrier integrity in the aetiology of dandruff. Microorganisms and dandruff The scalp as a microbial habitat Each region of the skin has a distinct ecological niche. To summarize the above paragraphs, although there remains a substantial consensus that Malassezia , along with individual susceptibility, is a key predisposing factor in dandruff and despite the enormous advances in our ability to characterize the genomic and metabolic characteristics of scalp relevant strains, a satisfactory explanation for the mechanism by which Malassezia. spp. The preliminary characterization of the dandruff scalp SC has indicated some similarities with winter- or surfactant-induced dry skin (xerosis) [ 60 ]. However, in comparison with dandruff, the depletion of intercellular lipids in dry skin is modest and other features such as parakeratosis are rarely observed in winter xerosis, observations that imply the dandruff scalp SC phenotype represents a more severe perturbation of epidermal function, keratinization, and overall barrier integrity than classical dry skin seen elsewhere on the body. Given these observations on the dandruff condition, it is likely that other elements of the holistic SC barrier are perturbed, for example the antimicrobial and antioxidant barrier. Consistent with the hypothesis of SC disruption, several observations about dandruff susceptibility are consistent with poor EPB function. First, only individuals prone to dandruff respond to the topical application of oleic acid (a known skin penetration enhancer and irritant) [ 33 ], and secondly, dandruff sufferers are more responsive (i.e. report a higher perception of itch) to histamine topically applied to the scalp [ 14 , 82 ]. The scalp is examined by quadrant under standardized lighting conditions. Each quadrant is rated for dandruff severity ( Table I ) and analysed statistically. The antidandruff efficacy of test products is assessed by examining the reduction in visual dandruff. This score is then compared with a suitable control. The longevity of antidandruff efficacy can be examined by placing subjects on a non-antidandruff shampoo at the end of the study test phase and monitoring for the return of dandruff flakes (regression phase). Washing skin with a liquid cleanser base (in the absence of any moisturizing ingredients) can reduce the level of fatty acids and cholesterol in the skin even after a single wash. Transmission electron micrographs of human skin washed ex vivo under exaggerated conditions have shown that non-ionic surfactant-based cleansers alter the lipid region to a greater extent than do mild cleansing bars with sodium cocoyl isethionate as the surfactant [ 96 ]. In such mild systems, the addition of saturated long-chain fatty acids, such as stearic and palmitic acid, lowers the tendency of the surfactant to damage lipid membranes. Conclusions In this review, we discussed the key factors in the development of dandruff. Growth of Malassezia , likely nourished by sebum, has long been associated with dandruff scalps, but the precise mechanisms underpinning the relationship between Malassezia and dandruff remain unclear. Despite this uncertainty, one of the more reliably observed features of the condition is that dandruff develops only in susceptible individuals, suggesting that additional factors may make the scalp epidermis vulnerable to damage from the growth of Malassezia and additional stressors.

Dandruff is a common but complex disorder with three major contributing factors: (1) individual predisposition, (2) scalp sebum and (3) Malassezia yeast colonization. To obtain further insights into the role of sebum in dandruff biogenesis, we analyzed scalp lipid species in a cohort of ten dandruff-free (control) and ten dandruff-afflicted volunteers by gas chromatography coupled to mass spectrometry. Lipid peroxidation levels and biochemical markers of oxidative stress were also assessed. Squalene, a major sebum component, was significantly more peroxidized in dandruff-affected scalps, resulting in significantly higher ratios of squalene monohydroperoxide (SQOOH)/squalene. This was observed when comparing dandruff-affected zones of dandruff subjects to both their non-affected zones and control subjects. In addition, other biomarkers such as malondialdehyde indicated that oxidative stress levels were raised on dandruff scalps. Surprisingly, differences regarding either free or bound fatty acids were fairly rare and minor. Certain novel findings, especially squalene peroxidation levels, were then confirmed in a validation cohort of 24 dandruff-affected subjects, by comparing dandruff-affected and non-dandruff zones from the same individuals. As SQOOH can induce both keratinocyte inflammatory responses and hyperproliferation in vitro, we hypothesized that increased SQOOH could be considered as a new etiological dandruff factor via its ability to impair scalp barrier function. Our results also indicated that Malassezia could be a major source of squalene peroxidation on the scalp.

BACKGROUND Dandruff is a chronic and relapsing scalp condition characterized by flaky scalp. Environmental and host factors (exposome) may alter the sebaceous gland activity, sebum composition, epidermal barrier function, and scalp microbiome balance, resulting in dandruff. Selenium disulfide (SeS2) improves the clinical signs of dandruff. OBJECTIVES To investigate the mode of action of SeS2 shampoo during treatment and relapse phases. MATERIALS & METHODS Two single-center studies assessed dandruff severity, subjective efficacy perception, microbial balance, microbiota diversity and sebum lipids. RESULTS SeS2 significantly (p≤0.01) reduced scaling and led to a significant decrease of Malassezia and Staphylococcus spp. counts in both lesional and non-lesional areas, compared to the vehicle at D28 returning to baseline levels at D56. Cutibacterium spp. levels were not different between the SeS2 and the vehicle treatment groups but had significantly increased with SeS2 (p<0.001) in the lesional zone at D56. The ratio Malassezia spp./Cutibacterium spp. decreased significantly in lesional zones compared to baseline levels, at both D28 and D35 (p<0.001). The total squalene content significantly increased (p<0.05), whereas peroxided squalene had significantly decreased by almost 50% at D31. The ratio triglycerides/free fatty acids significantly (p<0.0001) increased, almost 5-fold, between D0 and D31. SeS2 shampoo was very well tolerated. CONCLUSION SeS2 is beneficial in scalp dandruff, even after treatment interruption. It is well tolerated, rebalances the equilibrium between the main bacterial and fungal populations, and improves sebum quality.

The structure of the skin and its function varies in the different regions of the body. The scalp with its high density of large hair follicles and abundance of sebaceous glands constitutes a unique area. The scalp is apparently less prone to inflammation. Some dermatological conditions of the scalp will be discussed: dermatophytic infection (tinea capitis) as a common infectious process affecting both the skin and hair; pediculosis capitis, the unique parasitic infestation; and inflammatory diseases, seborrhoeic dermatitis, dandruff and psoriasis. Review Common skin conditions affecting the scalp: Tinea Capitis, Pediculosis Capitis, Seborrhoeic Dermatitis, Dandruff, Psoriasis ./:rcr* llh, ]ID De pzrrtnrcnt of l)clrnatolog', f lniversit) o1'I)re krria ' Introduction -fhe structure of the skin anrl its firnction r,arie s in the diII'erent regions o1'the lxrrh'. The scalp urth its higl <lcnsin' <lf large hair fbllicles :urd :rbunclance o1'sebaceous glancls runstitutes ir unirlue ar-ea. The sca$ is apparetrtll' less l)rone to inllarnmation. It is nevertheless a safe drug and there do not seem to be any absolute contraindications. PEDICULOSIS CAPITIS (HEAD LICE) Head lice (Pediculosis humanus capitis) are transmitted among persons living in unhealthy, crowded conditions and sharing hats, brushes and combs. Long hair and elaborate styles ofhairdressing which prevent frequent washing increase the susceptibility. Head lice is most common in children but no age is immune. The eggs are attached to the hair and when they hatch, numerous nits, resembling dandruff, are left behind. These are seen mainly in the occipital and postauricular regions. Pruritus is the most characteristic manifestation. Scratching often leads to secondary infection and the occipital lymph nodes are frequently enlarged. The diagnosis is often missed when the possibility is not considered. Nits firmly attached to the hair shafts are not easily pulled off. This differentiates them from dandruff scales. The treatment of choice is to apply Permethrin lo/o cream rinse. Applica- tion of Permethrin should be preceded by a regular shampooing and towel drying. Permethrin has to be applied to the hair and scalp for l0 minutes and then rinsed off with water. A single treatment is usually sufficient. Permethrin is safe for children over 2 years ofage. An alternative therapy is to apply 10% Crotamiton cream (Eurax). It is left on the scalp for 24 hours and then shampooed. This treatment can be repeated in 7-10 days, if necessary. SEBORRHOEIC DERMA'TITIS OF THE SCALP (FTGURES 5 AND 6) Seborrhoeic dermatitis is a common inflammatory condition presenting clinically as erythematous, scaling eruption, localized to the scalp, eyebrows, postauricular areas, central face, central chest and back and flexural areas, the so-called seborrhoeic areas. Although these lesions are common and are clinically quite distinctive the cause of seborrhoeic dermatitis remains elusive. The seborrhoeic state is asso- ciated with increased susceptibility to pyogenic infections and invasion by Pityrosporum ovale. Whether Pityro- sporum ovale causes seborrhoeic dermatitis is not clear. Scalp scales produced by seborrhoeic dermatitis provide a good nutrient for the growth of this lipophilic yeast and increased presence of Pityrosporum ovale may well be a secondary and not primary event. Clinically seborrhoeic dermatitis of the scalp presents as areas of erythema covered by yellow, greasy scales. Lesions often extend beyond the margins of the hair onto the forehead and behind the ears. Seborrhoeic dermatitis may be associated with transient alopecia. The medicated shampoo should be applied less often, once a week, but for a longer time, 20 to 30 minutes. This shampoo should be followed by a nonmedicated shampoo and the usual moisturizers or conditioners. When the scalp is considerably inflamed or there is no response to the shampoos topical steroids should be applied. Often more fatty vehicles shouldbe used, ointments SA l'am Pmtt 2003:45(ll) rather than lotions and gels, particularly in f-emales with hot-pressed hair. DANDRUFF (PITYRIASIS CAPITIS) In dandruif there is desquamation of small, flaky scales f}om an otherwise normal scalp. The aetiology of dandruff is not clear and the literature is confusing.5 It is usually accepted that dandrutf and seborrhoeic dermatitis represents two ends of a diseasc spectrum. Similarremedies, medicated shampoos, were fbund equally eftbctive in the treatment of both conditions. As in seborrhoeic dermatitis shampoos containing tar, salicylic acid, selenium sr"rlfide and ketoconazole are recommended. Usually twice weekly usage controls the scaling. PSORIASIS OF THE SCALP (FTGURES 7 AND 8) Psoriasis affects approximately 2%o of the world population and scalp is involved in about 50% ofall psoriatics. Usually there are psoriatic lesions elsewhere but the disease can be limited to the scalp. After the removal of the scales topical corticosteroids in lotions, gels or tbarns should be applied. The usual application schedule consists of interrnittent applications 3 to 4 times wcekly. Vitamin D3 analogue calcipo- triol (DovonexO) has a substantial antipsoriatic efl'ect. It is available in a lotion fbrrnulation for the treatment of the scalp lesions. It has to be noted that maximum efficacy of calcipotriol lotion is reached after 8 weeks, whereas maxi- mal efticacy of a topical corticosteroid is reached afler 2 to 3 Shuster S. The aetiology ofdandruffand the mode ofaction oftherapeutic agents. B/i/J Dennutol 198,+. I I l:235-242. 6. Van de Kerkhof PC, Franssen ME. Psoriasis of the scalp. Diagnosis and managcment. Am J (;lin Demntol 2001, 2:159-165. Product News Zaditen Eye Drops | \\:, ') lt Adcock Ingram is pleased to announce the launch of Zaditen Eye Drops into the Novartis Ophthahnics range ofeye drops from the 20 August 2003. Each I ml of Zaditen Eye Drops contains Ketotifen fumarate 0,345rng equivalent to ketotif-en 0,25 mg.

Seborrheic Dermatitis (SD) and dandruff are of a continuous spectrum of the same disease that affects the seborrheic areas of the body. Dandruff is restricted to the scalp, and involves itchy, flaking skin without visible inflammation. SD can affect the scalp as well as other seborrheic areas, and involves itchy and flaking or scaling skin, inflammation and pruritus. Various intrinsic and environmental factors, such as sebaceous secretions, skin surface fungal colonization, individual susceptibility, and interactions between these factors, all contribute to the pathogenesis of SD and dandruff. In this review, we summarize the current knowledge on SD and dandruff, including epidemiology, burden of disease, clinical presentations and diagnosis, treatment, genetic studies in humans and animal models, and predisposing factors. Genetic and biochemical studies and investigations in animal models provide further insight on the pathophysiology and strategies for better treatment.

The scalp microbiome represents an array of microorganisms important in maintaining scalp homeostasis and mediating inflammation. Scalp microbial dysregulation has been implicated in dermatologic conditions including alopecia areata (AA), dandruff/seborrheic dermatitis (D/SD), scalp psoriasis (SP) and folliculitis decalvans (FD). Understanding the impact of scalp microbial dysbiosis gives insight on disease pathophysiology and guides therapeutic decision making. Herein we review the scalp microbiome and its functional role in scalp conditions by analysis of metagenomic medical literature in alopecia, D/SD, SP, and other dermatologic disease.Increased abundance of Malassezia, Staphylococcus, and Brevibacterium was associated with SD compared to healthy controls. A higher proportion of Corynebacterium, actinobacteria, and firmicutes are present in AA patients, and lower proportions of Staphylococcus caprae are associated with worse clinical outcomes. Decreased prevalence of actinobacteria and Propionibacterium and increased firmicutes, staphylococcus, and streptococcus are associated with scalp psoriasis. Studies of central centrifugal cicatricial alopecia (CCCA) suggest scalp microbial composition contributes to CCCA's pro-inflammatory status. The most common organisms associated with FD include methicillin-resistant S. aureus and S. lugdunensis. Antifungals have been a mainstay treatment for these diseases, while other alternatives including coconut oils and shampoos with heat-killed probiotics have shown considerable potential efficacy by replenishing the scalp microbiome.