Part 2: Understanding the role of Malassezia spp. in skin disorders: pathogenesis of Malassezia associated skin infections

ABSTRACT

Introduction

Malassezia is a major component of the skin microbiome, a lipophilic symbiotic organism of the mammalian skin, which can switch to opportunistic pathogens triggering multiple dermatological disorders in humans and animals. This phenomenon is favored by endogenous and exogenous host predisposing factors, which may switch Malassezia from a commensal to a pathogenic phenotype.

Area covered

This review summarizes and discusses the most recent literature on the pathogenesis of Malassezia yeasts, which ultimately results in skin disorders with different clinical presentation. A literature search of Malassezia pathogenesis was performed via PubMed and Google scholar (up to May 2023), using the following keywords: Pathogenesis and Malassezia;host risk factors and Malassezia, Malassezia and skin disorders; Malassezia and virulence factors: Malassezia and metabolite production; Immunology and Malassezia.

Expert opinion

Malassezia yeasts can maintain skin homeostasis being part of the cutaneous mycobiota; however, when the environmental or host conditions change, these yeasts are endowed with a remarkable plasticity and adaptation by modifying their metabolism and thus contributing to the appearance or aggravation of human and animal skin disorders.

KEYWORDS:

• Enzyme production
• host risk factors
• immunology
• malassezia spp
• metabolite production
• pathogenesis

Article highlights

• The assessment of the role of Malassezia yeasts in skin disorders is still a debated issue and needs further study.

• The relationship between host and Malassezia metabolism is pivotal for understanding the role of Malassezia in the pathogenesis of skin infection.

• Exogenous and endogenous risk factors play a role in inducing Malassezia switch from commensal to pathogenic phenotype.

• The cell wall composition as well as the change in Malassezia metabolisms have a role in skin disorders with different clinical manifestations.

• Phospholipase, lipase, hemolysin and proteases play a role in the occurrence of clinical manifestations.

• Production of indole compounds are incriminated in many aspects of skin physiology, cellular homeostasis, skin pigmentation, skin immunity and pathogenesis of skin disorders.

• Production of azelaic acid and melanin inhibits phagocytosis and decreases the host oxidative capability and are indirectly involved in controlling host immune response.

• Direct production of allergens, activation of the complement system and IL-23/IL-17 axis control fungal growth and mediate immunopathology.

• Prompt reversal of underlying risk factors are useful for optimal outcome.

• Future studies focused on understanding Malassezia virulence determinants associated with specific skin disorders are needed for designing targeted interventions.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.