Seborrhoeic dermatitis: current treatment practices

The yeast-human coevolution: Fungal transition from passengers, colonizers, and invaders

Fungi are the cause of more than a billion infections in humans every year, although their interactions with the host are still neglected compared to bacteria. Major systemic fungal infections are very unusual in the healthy population, due to the long history of coevolution with the human host. Humans are routinely exposed to environmental fungi and can host a commensal mycobiota, which is increasingly considered as a key player in health and disease. Here, we review the current knowledge on host-fungi coevolution and the factors that regulate their interaction. On one hand, fungi have learned to survive and inhabit the host organisms as a natural ecosystem, on the other hand, the host immune system finely tunes the response toward fungi. In turn, recognition of fungi as commensals or pathogens regulates the host immune balance in health and disease. In the human gut ecosystem, yeasts provide a fingerprint of the transient microbiota. Their status as passengers or colonizers is related to the integrity of the gut barrier and the risk of multiple disorders. Thus, the study of this less known component of the microbiota could unravel the rules of the transition from passengers to colonizers and invaders, as well as their dependence on the innate component of the host's immune response. This article is categorized under: Infectious Diseases > Environmental Factors Immune System Diseases > Environmental Factors Infectious Diseases > Molecular and Cellular Physiology.

Serum Levels of 25-Hydroxyvitamin D in Patients with Seborrheic Dermatitis: A Case-Control Study

Several autoimmune papulosquamous skin conditions such as psoriasis, systemic lupus erythematous, and lichen planus have been associated with vitamin D deficiency or correlated with serum vitamin D level. This study was aimed at comparing the 25-hydroxyvitamin D (25(OH)D) status in patients with facial or scalp seborrheic dermatitis with healthy subjects. This case-control study included 289 patients (118 with psoriasis and 171 sex- and age-matched control subjects) from the outpatient clinic of two hospital dermatology departments in the west of Mazandaran province, Iran. All patients and control subjects were studied during one season to avoid seasonal variations in vitamin D levels. Serum mean ± standard deviation of 25(OH)D levels were significantly lower in seborrheic dermatitis patients than in control subjects (20.71 ± 8.16 vs. 23.91 ± 7.78, P = 0.007). Serum 25(OH)D levels were negatively associated with the risk of developing seborrheic dermatitis (odds ratio (OR): 0.898, 95% confidence interval (Cl): 0.840-0.960, P = 0.002). Also, vitamin D under 30 ng/ml was associated with OR: 4.22 (95% Cl: 1.077-16.534, P = 0.039) for seborrheic dermatitis. The severity of scalp disease was significantly associated with serum 25(OH)D level (P = 0.003). Cases with severe scalp scores had significantly lower serum 25(OH)D level compared to moderate OR score (P = 0.036). A similar trend was not seen in the facial disease. The 25(OH)D values are significantly lower in seborrheic dermatitis patients than in healthy subjects. Furthermore, the scalp disease severity was associated with lower serum 25(OH)D level. Our results may suggest that vitamin D may play a role in the pathogenesis of seborrheic dermatitis.

Vitamin D in trichology: a comprehensive review of the role of vitamin D and its receptor in hair and scalp disorders

Vitamin D plays an important role in maintaining the homeostasis of various biological systems. Beside its well-known function in calcium and phosphate metabolism, it plays a major role in pathophysiology of skin and adnexa. Indeed, vitamin D, through its receptor (VDR), decreases keratinocyte proliferation, improves their differentiation and modulates both cutaneous innate (antimicrobial activity and antigen presentation) and adaptative immunity (T and B lymphocyte function). The maintenance of normal hair is dependant on the integrity of the dermis, epidermis and hair cycles. Beside its effect on epidermal differentiation, VDR plays a vital role in preserving the hair follicle integrity. While the relevance of VDR has been fully elucidated, the real value of vitamin D in the hair follicle cycle still remains uncertain. To date, results in literature remain contradicting and far from definitive; still, the role of vitamin D in the various forms of human alopecia is likely to be significant. The aim of this article is to review evidence about the role of vitamin D and its receptor in trichology, with a focus on scarring and non-scarring alopecia and in particular on the potential therapeutic use of Vitamin D for hair and scalp disorders.

Topical Treatment of Facial Seborrheic Dermatitis: A Systematic Review

BACKGROUND

Facial seborrheic dermatitis (SD), a chronic inflammatory skin condition, can impact quality of life, and relapses can be frequent. Three broad categories of agents are used to treat SD: antifungal agents, keratolytics, and corticosteroids. Topical therapies are the first line of defense in treating this condition.

OBJECTIVE

Our objective was to critically review the published literature on topical treatments for facial SD.

METHODS

We searched PubMed, Scopus, Clinicaltrials.gov, MEDLINE, Embase, and Cochrane library databases for original clinical studies evaluating topical treatments for SD. We then conducted both a critical analysis of the selected studies by grading the evidence and a qualitative comparison of results among and within studies.

RESULTS

A total of 32 studies were eligible for inclusion, encompassing 18 topical treatments for facial SD. Pimecrolimus, the focus of seven of the 32 eligible studies, was the most commonly studied topical treatment.

CONCLUSION

Promiseb^®, desonide, mometasone furoate, and pimecrolimus were found to be effective topical treatments for facial SD, as they had the lowest recurrence rate, highest clearance rate, and the lowest severity scores (e.g., erythema, scaling, and pruritus), respectively. Ciclopirox olamine, ketoconazole, lithium (gluconate and succinate), and tacrolimus are also strongly recommended (level A recommendations) topical treatments for facial SD, as they are consistently effective across high-quality trials (randomized controlled trials).

Increased hair shedding may be associated with the presence of Pityrosporum ovale

BACKGROUND AND OBJECTIVE

Although the available data show that hair loss is an important cosmetic problem worldwide, the pathogenesis of common hair shedding is not fully understood. The aim of this study was to evaluate the association between hair shedding and cutaneous Malassezia infection. Malassezia fungi have been the suspected cause of dandruff for more than a century. Previously referred to as Pityrosporum ovale or P. orbiculare, these fungi are now known to consist of at least seven species.

METHODS

Over a 4-year period, we obtained 300 hair samples from medical students. Based on the clinical history and a hair-pull test, the participants were divided into two groups: normal subjects and subjects with hair shedding. The students' scalp skin was gently scraped, smeared on a slide, colored by methylene blue, and observed under 10x magnification.

RESULTS

All participants who had positive smears with >or=3 P. ovale organisms per low-power microscopic field (10x) were defined as 'carriers.' Seventy-six percent of students were Malassezia carriers. The prevalence of positive smears was significantly higher among subjects with hair shedding than among normal subjects (89.92% vs 9.52%, p<0.001). Furthermore, participants with positive smears had a significantly higher frequency of hair loss complaints and positive hair-pull tests.

CONCLUSION

The proportion of subjects who were carriers of Malassezia yeasts was significantly higher in the group with hair shedding, and our results therefore raise the possibility of a relationship between this unicellular organism and hair loss. Our study findings should be explored in a larger series of patients.

Fungal virulence, vertebrate endothermy, and dinosaur extinction: is there a connection?

Fungi are relatively rare causes of life-threatening systemic disease in immunologically intact mammals despite being frequent pathogens in insects, amphibians, and plants. Given that virulence is a complex trait, the capacity of certain soil fungi to infect, persist, and cause disease in animals despite no apparent requirement for animal hosts in replication or survival presents a paradox. In recent years studies with amoeba, slime molds, and worms have led to the proposal that interactions between fungi and other environmental microbes, including predators, select for characteristics that are also suitable for survival in animal hosts. Given that most fungal species grow best at ambient temperatures, the high body temperature of endothermic animals must provide a thermal barrier for protection against infection with a large number of fungi. Fungal disease is relatively common in birds but most are caused by only a few thermotolerant species. The relative resistance of endothermic vertebrates to fungal diseases is likely a result of higher body temperatures combined with immune defenses. Protection against fungal diseases could have been a powerful selective mechanism for endothermy in certain vertebrates. Deforestation and proliferation of fungal spores at cretaceous-tertiary boundary suggests that fungal diseases could have contributed to the demise of dinosaurs and the flourishing of mammalian species.