Tinea versicolor: Ultrastructural Studies on Hypopigmented and Hyperpigmented Skin

Karaoui, R. M.; Bou-Resli, M. N.; Al-Zaid, N. S.; Mousa, A.

doi:10.1159/000250253

Cited by 35 publications

(24 citation statements)

References 11 publications

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“…Several theories have been proposed to explain hypopigmentation, including the filtering of UV light by the growth of the organism in the skin (14), a block in the transfer of melanosomes to keratinocytes (14,89,121,153,208), and the inhibition of melanin production by azelaic acid (180,302) or by lipoxygenase (304). Other groups have suggested that the hyperpigmentation of lesions was due to inflammation (116,153), increased skin thickness, or larger numbers of organisms in the skin (153).…”

Section: Pityriasis Versicolormentioning

confidence: 99%

Immunology of Diseases Associated withMalasseziaSpecies

2002

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SUMMARY Malassezia species are members of the human cutaneous commensal flora, in addition to causing a wide range of cutaneous and systemic diseases in suitably predisposed individuals. Studies examining cellular and humoral immune responses specific to Malassezia species in patients with Malassezia-associated diseases and healthy controls have generally been unable to define significant differences in their immune response. The use of varied antigenic preparations and strains from different Malassezia classifications may partly be responsible for this, although these problems can now be overcome by using techniques based on recent work defining some important antigens and also a new taxonomy for the genus. The finding that the genus Malassezia is immunomodulatory is important in understanding its ability to cause disease. Stimulation of the reticuloendothelial system and activation of the complement cascade contrasts with its ability to suppress cytokine release and downregulate phagocytic uptake and killing. The lipid-rich layer around the yeast appears to be pivotal in this alteration of phenotype. Defining the nonspecific immune response to Malassezia species and the way in which the organisms modulate it may well be the key to understanding how Malassezia species can exist as both commensals and pathogens.

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Section: Pityriasis Versicolormentioning

confidence: 99%

Immunology of Diseases Associated withMalasseziaSpecies

2002

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“…Depigmentation occurs frequently in affected areas, causing a pronounced loss of melanin even after successful antimycotic therapy. Histopathological and ultrastructural examinations of the lesions have led to somewhat contradictory findings, such as decreased numbers of melanosomes [8] and melanocytes, [9] disturbed transport of melanosomes to keratinocytes, [10] and morphological changes in melanocytes that were ascribed to toxic influences. [11,12] This prompted us to investigate the influence of Malassezia alkaloids on cultured primary human melanocytes.…”

Section: Introductionmentioning

confidence: 99%

Malassezin, a Novel Agonist of the Aryl Hydrocarbon Receptor from the Yeast Malassezia furfur, Induces Apoptosis in Primary Human Melanocytes

et al. 2005

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Pityriasis versicolor is the most common skin mycosis in humans worldwide. Yeasts of the genus Malassezia, particularly M. furfur, a saprophyte occurring widely on human skin, are generally regarded as the causative agents. Pityriasis versicolor is often accompanied by a long-lasting depigmentation that persists even after successful antimycotic therapy. M. furfur is able to convert tryptophan into a variety of indole alkaloids, some of them showing biological properties that correlate well with certain clinical features of pityriasis versicolor. This suggests a possible role for these compounds in the depigmentation process. We now report that human melanocytes undergo apoptosis when exposed to the crude mixture of tryptophan metabolites from M. furfur. The active compound was identified as malassezin, previously isolated by us from the same source and characterized as an agonist of the aryl hydrocarbon (Ah) receptor. The compound could, therefore, contribute to the marked depigmentation observed during the course of pityriasis versicolor.

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“…The hypopigmentation is related to dicarboxylic acids produced by fungi that may inhibit the dopa-tyrosine reaction that produces host melanin [22]. According to Karaoui, melanocyte damage also is caused by fungi, varying from altered melanosomes, damage to mitochondria to actual degeneration [23]. The size and distribution of melanosomes can be different between patients: when the melanosomes are abnormally small hypopigmentation occurs, while when the melanosomes are extra-large hyperpigmentation appears [22].…”

Section: Dermatophytosismentioning

confidence: 99%

Update on Fungal Disease: From Establish Infection to Clinical Manifestation

Melo¹,

Scorzoni²,

Rossi³

et al. 2017

J Biotechnol Biomater

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Fungal diseases have emerged as an important cause of morbidity and mortality, especially among immunocompromised patients. Pathogenic fungi have evolved an array of virulence factors to survive within the host and to outwit immune defenses. Fungi may cause a wide range of diseases in humans that range in extent from superficial to disseminated infections. Generally, the site of infections classifies the type of fungal disease, which can be divided into superficial, cutaneous, subcutaneous and systemic. In addition, the fungal virulence factors determine whether the infection will become established in the host. A primary pathogen may infect an immunologically normal host, whereas, an opportunistic pathogen requires some compromise of the host immune defenses in order for the infection to become established. This article covers the main fungi that are responsible for the increase of the fungal infections.Keywords: Fungal infections; Virulence; Yeast; Opportunistic infections; Endemic mycosis Fungal InfectionsFungal diseases have changed constantly in the last years. The virulence of these microorganisms has been adapted according to the human host, promoting a range of clinical manifestation. Several are the ways by which fungi promote a disease depending on human body part involved by the microorganism and the immunologic system of the host [1].In this review, we discuss the main fungal pathogens responsible for causing several diseases, highlighting on their virulence associate to clinical manifestation and the difficulty to accomplish the treatment. Superficial and cutaneous fungal diseasesSuperficial and cutaneous fungal infections are very common and occur worldwide affecting millions of people, especially immunocompromised patients. The most common types of these infections are dermatophytosis (tinea or ringworm), pityriasis versicolor (formerly tinea versicolor) and candidiasis (moniliasis). These occur by fungal invasion into the skin, keratinized tissues and mucous membranes [2]. Trichosporon and Fusarium species also cause superficial fungal infection, but also may be considered an invasive pathogen that may cause a systemic infection [3,4].Dermatophytosis: Dermatophytes are fungi that invade keratinized structures of humans and animals producing a condition called dermatophytosis or, more commonly, tinea [5,6]. These fungi belong to three main genera Trichophyton, Microsporum and Epidermophyton, of these T. rubrum is the most prevalent species worldwide [7,8]. The mechanisms of pathogenicity of these fungi are not yet well understood. There are several studies focusing on keratinolytic proteases (keratinases) produced by dermatophytes, but it is not known how these fungi regulate the use of these proteases to obtain nutrients from the stratum corneum substrate they invade, and whether there are additional roles of these proteins in adhesion and immunomodulation [9].To establish the infection, the contact of arthroconidia or hyphal fragmens with the host skin is essential. The fungi express spe...

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Tinea versicolor: Ultrastructural Studies on Hypopigmented and Hyperpigmented Skin

Cited by 35 publications

References 11 publications

Immunology of Diseases Associated withMalasseziaSpecies

Immunology of Diseases Associated withMalasseziaSpecies

Malassezin, a Novel Agonist of the Aryl Hydrocarbon Receptor from the Yeast Malassezia furfur, Induces Apoptosis in Primary Human Melanocytes

Update on Fungal Disease: From Establish Infection to Clinical Manifestation

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