Inherited ichthyosis and fungal infection: an update on pathogenesis and treatment strategies

Staphylococcus aureus bacteremia and infective endocarditis in a patient with epidermolytic hyperkeratosis: A case report

BACKGROUND

Staphylococcus aureus bacteraemia (SAB) is among the leading causes of bacteraemia and infectious endocarditis. The frequency of infectious endocarditis (IE) among SAB patients ranges from 5% to 10%-12%. In adults, the characteristics of epidermolytic hyperkeratosis (EHK) include hyperkeratosis, erosions, and blisters. Patients with inflammatory skin diseases and some diseases involving the epidermis tend to exhibit a disturbed skin barrier and tend to have poor cell-mediated immunity.

CASE SUMMARY

We describe a case of SAB and infective endocarditis in a 43-year-old male who presented with fever of unknown origin and skin diseases. After genetic tests, the skin disease was diagnosed as EHK.

CONCLUSION

A breached skin barrier secondary to EHK, coupled with inadequate sanitation, likely provided the opportunity for bacterial seeding, leading to IE and deep-seated abscess or organ abscess. EHK may be associated with skin infection and multiple risk factors for extracutaneous infections. Patients with EHK should be treated early to minimize their consequences. If patients with EHK present with prolonged fever of unknown origin, IE and organ abscesses should be ruled out, including metastatic spreads.

Distinct skin microbiome community structures in congenital ichthyosis

BACKGROUND

The ichthyoses are rare genetic keratinizing disorders that share the characteristics of an impaired epidermal barrier and increased risk of microbial infections. Although ichthyotic diseases share a T helper (Th) 17 cell immune signature, including increased expression of antimicrobial peptides, the skin microbiota of ichthyoses is virtually unexplored.

OBJECTIVES

To analyse the metagenome profile of skin microbiome for major congenital ichthyosis subtypes.

METHODS

Body site-matched skin surface samples were collected from the scalp, upper arm and upper buttocks of 16 healthy control participants and 22 adult patients with congenital forms of ichthyosis for whole metagenomics sequencing analysis.

RESULTS

Taxonomic profiling showed significant shifts in bacteria and fungi abundance and sporadic viral increases across ichthyosis subtypes. Cutibacterium acnes and Malassezia were significantly reduced across body sites, consistent with skin barrier disruption and depletion of lipids. Microbial richness was reduced, with specific increases in Staphylococcus and Corynebacterium genera, as well as shifts in fungal species, including Malassezia. Malassezia globosa was reduced at all body sites, whereas M. sympodialis was reduced in the ichthyotic upper arm and upper buttocks. Malassezia slooffiae, by contrast, was strikingly increased at all body sites in participants with congenital ichthyosiform erythroderma (CIE) and lamellar ichthyosis (LI). A previously undescribed Trichophyton species was also detected as sporadically colonizing the skin of patients with CIE, LI and epidermolytic ichthyosis subtypes.

CONCLUSIONS

The ichthyosis skin microbiome is significantly altered from healthy skin with specific changes predominating among ichthyosis subtypes. Skewing towards the Th17 pathway may represent a response to the altered microbial colonization in ichthyosis. What is already known about this topic? The skin microbiome of congenital ichthyoses is largely unexplored. Microbes play an important role in pathogenesis, as infections are common. The relative abundances of staphylococci and corynebacteria is increased in the cutaneous microbiome of patients with Netherton syndrome, but extension of these abundances to all congenital ichthyoses is unexplored. What does this study add? A common skin microbiome signature was observed across congenital ichthyoses. Distinct microbiome features were associated with ichthyosis subtypes. Changes in microbiome may contribute to T helper 17 cell immune polarization. What is the translational message? These data provide the basis for comparison of the microbiome with lipidomic and transcriptomic alterations in these forms of ichthyosis and consideration of correcting the dysbiosis as a therapeutic intervention.

Juvenile-onset PSAT1-related neuropathy: A milder phenotype of serine deficiency disorder

Background: Primary serine deficiency disorders have a broad range of the phenotypic spectrum. As an inborn error of metabolism, individuals with severe phenotype may be easily recognized with Neu-Laxova syndrome. However, late-onset mild phenotypes may be underdiagnosed and will lead to disastrous consequences due to treatment delays.

Materials and Methods: Clinical features of patients with serine deficiency disorders were summarized in two unrelated patients. Skin and sural nerve biopsies were conducted on the patients. Whole exome sequencing (WES) was performed in the index patients. Sanger sequencing was used to analyze family cosegregation.

Results: Patient 1 was a 19-year-old male presenting with infancy-onset ichthyosis and juvenile-onset neuropathy. Patient 2 was a 17-year-old male manifesting childhood-onset ichthyosis and juvenile-onset neuropathy. Except for nystagmus, no other developmental or neurodegenerative disorders were found in the patients. Electrophysiological studies indicated a severe sensorimotor axonal neuropathy with a possible demyelinating component. High-dose oral L-serine and glycine completely alleviated skin lesions and only slightly improved neuropathy symptoms. Skin biopsies showed typical features consistent with ichthyosis and severe loss of unmyelinated axons. Sural biopsies revealed a severe loss of axons and a few thinly myelinated fibers. WES found the same homozygous variant c.43G > C (p.A15P) in the PSAT1 gene, which was cosegregated in the two families.

Conclusions: The skin and nervous system may be the main affected targets in serine deficiency disorders. Our patients show a more simple and mild phenotype of PSAT1-related serine deficiency disorder. The pathological changes and regenerative ability of skin and peripheral nerves determine their response to serine supplements.

Revisiting the Roles of Filaggrin in Atopic Dermatitis

The discovery in 2006 that loss-of-function mutations in the filaggrin gene (FLG) cause ichthyosis vulgaris and can predispose to atopic dermatitis (AD) galvanized the dermatology research community and shed new light on a skin protein that was first identified in 1981. However, although outstanding work has uncovered several key functions of filaggrin in epidermal homeostasis, a comprehensive understanding of how filaggrin deficiency contributes to AD is still incomplete, including details of the upstream factors that lead to the reduced amounts of filaggrin, regardless of genotype. In this review, we re-evaluate data focusing on the roles of filaggrin in the epidermis, as well as in AD. Filaggrin is important for alignment of keratin intermediate filaments, control of keratinocyte shape, and maintenance of epidermal texture via production of water-retaining molecules. Moreover, filaggrin deficiency leads to cellular abnormalities in keratinocytes and induces subtle epidermal barrier impairment that is sufficient enough to facilitate the ingress of certain exogenous molecules into the epidermis. However, although FLG null mutations regulate skin moisture in non-lesional AD skin, filaggrin deficiency per se does not lead to the neutralization of skin surface pH or to excessive transepidermal water loss in atopic skin. Separating facts from chaff regarding the functions of filaggrin in the epidermis is necessary for the design efficacious therapies to treat dry and atopic skin.

Ichthyosis, psoriasiform dermatitis, and recurrent fungal infections in patients with biallelic mutations in PERP

BACKGROUND

Germline autosomal dominant and autosomal recessive mutations in PERP, encoding p53 effector related to PMP-22 (PERP), a component of epidermal desmosomes, have been associated with a spectrum of keratodermas. Monoallelic nonsense mutations cause Olmsted syndrome with severe periorificial keratoderma and palmoplantar keratoderma (PPK). Biallelic recessive frameshift and missense mutations are associated with milder forms of the disease, including generalised erythrokeratoderma and PPK.

OBJECTIVES

To add new insights into the genotype-phenotype correlations as a consequence of PERP mutations and to provide a comprehensive review of the literature.

METHODS

Among 26 previously unresolved families within a cohort of 180 extended Iranian families with syndromic or non-syndromic ichthyosis, two families with shared clinical features were examined by whole-exome sequencing and genome-wide homozygosity mapping. Mycological and dermatopathological studies were performed to further characterise their atypical phenotypic presentations.

RESULTS

In two unrelated multiplex consanguineous families affected by ichthyosis, two novel biallelic PERP variants, NM_022121.5, c.89T > C, p.Leu30Pro and c.466G > C, p.Gly156Arg, located inside of genomic homozygosity regions of the probands were detected. Interestingly, some patients had areas of scaly psoriasiform plaques on the background of generalised ichthyosis that appeared during active cutaneous fungal infections. Mycological examinations of these lesions revealed infections caused by Candida albicans, Epidermophyton floccosum, or Trichophyton rubrum. Histopathology of the psoriasiform lesions shared some features with psoriasis, which when combined with clinical presentation, led to incorrect diagnosis of guttate psoriasis or pustular psoriasis.

CONCLUSIONS

PERP variants in ichthyosis patients can confer susceptibility to recalcitrant cutaneous fungal infections. Additionally, patients with episodic psoriasiform dermatitis in the setting of keratoderma should be considered for PERP genotyping and cutaneous fungal examinations.