Designation of Autoinflammatory Skin Manifestations With Specific Genetic Backgrounds

Autoinflammatory Keratinization Diseases-The Concept, Pathophysiology, and Clinical Implications

Recent advances in medical genetics elucidated the background of diseases characterized by superficial dermal and epidermal inflammation with resultant aberrant keratosis. This led to introducing the term autoinflammatory keratinization diseases encompassing entities in which monogenic mutations cause spontaneous activation of the innate immunity and subsequent disruption of the keratinization process. Originally, autoinflammatory keratinization diseases were attributed to pathogenic variants of CARD14 (generalized pustular psoriasis with concomitant psoriasis vulgaris, palmoplantar pustulosis, type V pityriasis rubra pilaris), IL36RN (generalized pustular psoriasis without concomitant psoriasis vulgaris, impetigo herpetiformis, acrodermatitis continua of Hallopeau), NLRP1 (familial forms of keratosis lichenoides chronica), and genes of the mevalonate pathway, i.e., MVK, PMVK, MVD, and FDPS (porokeratosis). Since then, endotypes underlying novel entities matching the concept of autoinflammatory keratinization diseases have been discovered (mutations of JAK1, POMP, and EGFR). This review describes the concept and pathophysiology of autoinflammatory keratinization diseases and outlines the characteristic clinical features of the associated entities. Furthermore, a novel term for NLRP1-associated autoinflammatory disease with epithelial dyskeratosis (NADED) describing the spectrum of autoinflammatory keratinization diseases secondary to NLRP1 mutations is proposed.

Genetics of Generalized Pustular Psoriasis: Current Understanding and Implications for Future Therapeutics

Psoriasis is a chronic inflammatory skin disease characterized by the appearance of clearly demarcated erythematous and scaly plaques. It can be divided into various types, including plaque, nail, guttate, inverse, and pustular psoriasis. Plaque psoriasis is the most commonly occurring type, though there is another rare but severe pustular autoinflammatory skin disease called generalized pustular psoriasis (GPP), which manifests with acute episodes of pustulation and systemic symptoms. Though the etiopathogenesis of psoriasis is not yet fully understood, a growing body of literature has demonstrated that both genetic and environmental factors play a role. The discovery of genetic mutations associated with GPP has shed light on our comprehension of the mechanisms of the disease, promoting the development of targeted therapies. This review will summarize genetic determinants as known and provide an update on the current and potential treatments for GPP. The pathogenesis and clinical presentation of the disease are also included for a comprehensive discussion.

Identification of a neutrophil-specific PIK3R1 mutation facilitates targeted treatment in a patient with Sweet syndrome

BackgroundAcute febrile neutrophilic dermatosis (Sweet syndrome) is a potentially fatal multiorgan inflammatory disease characterized by fever, leukocytosis, and a rash with a neutrophilic infiltrate. The disease pathophysiology remains elusive, and current dogma suggests that Sweet syndrome is a process of reactivity to an unknown antigen. Corticosteroids and steroid-sparing agents remain frontline therapies, but refractory cases pose a clinical challenge.MethodsA 51-year-old woman with multiorgan Sweet syndrome developed serious corticosteroid-related side effects and was refractory to steroid-sparing agents. Blood counts, liver enzymes, and skin histopathology supported the diagnosis. Whole-genome sequencing, transcriptomic profiling, and cellular assays of the patient's skin and neutrophils were performed.ResultsWe identified elevated IL-1 signaling in lesional Sweet syndrome skin caused by a PIK3R1 gain-of-function mutation specifically found in neutrophils. This mutation increased neutrophil migration toward IL-1β and neutrophil respiratory burst. Targeted treatment of the patient with an IL-1 receptor 1 antagonist resulted in a dramatic therapeutic response and enabled a tapering off of corticosteroids.ConclusionDysregulated PI3K/AKT signaling is the first signaling pathway linked to Sweet syndrome and suggests that this syndrome may be caused by acquired mutations that modulate neutrophil function. Moreover, integration of molecular data across multiple levels identified a distinct subtype within a heterogeneous disease that resulted in a rational and successful clinical intervention. Future patients will benefit from efforts to identify potential mutations. The ability to directly interrogate the diseased skin allows this method to be generalizable to other inflammatory diseases and demonstrates a potential personalized medicine approach for patients with clinically challenging disease.Funding SourcesBerstein Foundation, NIH, Veterans Affairs (VA) Administration, Moseley Foundation, and H.T. Leung Foundation.

Cutaneous Manifestations of Autoinflammatory Diseases

Autoinflammatory diseases (AIDs) are a heterogeneous group of disorders in which recurrent or continuous aseptic inflammation arises primarily through antigen-independent hyperactivation of the innate immune system. The skin is frequently involved with a wide variety of cutaneous manifestations, most of which are non-specific. Recognition of skin lesions in AIDs may sometimes provide clues for a correct diagnosis. In this review, the cutaneous involvements of >20 selected AIDs were summarized and organized into different categories based on their characteristic manifestations, such as urticarial dermatosis, neutrophilic dermatosis, granulomatosis, chilblain, lipodystrophy, and hyperkeratosis. With this classification scheme, cutaneous manifestations in AIDs could be more easily identified to facilitate diagnosis in clinical practice.

Down syndrome and type I interferon: not so simple

Down syndrome (DS) is characterized by a collection of clinical features including intellectual disability, congenital malformations, and susceptibility to infections and autoimmune diseases. While the presence of an extra chromosome 21 is known to cause DS, the precise genetic annotation linked to specific clinical features is largely missing. However, there is growing evidence that two genes located on chromosome 21, IFNAR1 and IFNAR2, play an important role in disease pathogenesis. These genes encode the two subunits of the receptor for type I interferons (IFN-I), a group of potent antiviral and pro-inflammatory cytokines. Human monogenic diseases caused by uncontrolled IFN-I production and response have been well characterized, and they clinically overlap with DS but also have notable differences. Herein, we review the literature characterizing the role of IFN-I in DS and compare and contrast DS to other IFN-mediated conditions. The existing IFN-I literature serves as a rich resource for testable hypotheses to elucidate disease mechanisms in DS and is likely to open novel therapeutic avenues.

An update on genetic basis of generalized pustular psoriasis (Review)

Generalized pustular psoriasis (GPP) is a rare and severe auto-inflammatory skin disease that is characterized by recurrent, acute onset, and generalized pustular eruptions on erythematous, inflamed skin. GPP is traditionally classified as a variant of psoriasis vulgaris, even though recent clinical, histological and genetic evidence suggests that it is a heterogeneous disease and requires a separate diagnosis. In recent years, variants of IL36RN, CARD14, AP1S3 and MPO genes have been identified as causative or contributing to genetic defects in a proportion of patients affected by GPP. These disease-related genes are involved in common inflammatory pathways, in particular in the IL-1/IL-36-chemokines-neutrophil pathogenic axis. At present, no standard therapeutic guidelines have been established for GPP management, and there is a profound need for novel efficacious treatments of GPP. Among them, biological agents antagonizing the IL-36 pathway are promising therapeutics. The aim of the present review is to provide the most recent updates on the genetics, genotype-phenotype correlation and pathological basis of GPP, as well as on biologic treatments available for GPP and relative clinical courses.

Notch Signaling Regulation in Autoinflammatory Diseases

Notch pathway is a highly conserved intracellular signaling route that modulates a vast variety of cellular processes including proliferation, differentiation, migration, cell fate and death. Recently, the presence of a strict crosstalk between Notch signaling and inflammation has been described, although the precise molecular mechanisms underlying this interplay have not yet been fully unravelled. Disruptions in Notch cascade, due both to direct mutations and/or to an altered regulation in the core components of Notch signaling, might lead to hypo- or hyperactivation of Notch target genes and signaling molecules, ultimately contributing to the onset of autoinflammatory diseases. To date, alterations in Notch signaling have been reported as associated with three autoinflammatory disorders, therefore, suggesting a possible role of Notch in the pathogenesis of the following diseases: hidradenitis suppurativa (HS), Behçet disease (BD), and giant cell arteritis (GCA). In this review, we aim at better characterizing the interplay between Notch and autoinflammatory diseases, trying to identify the role of this signaling route in the context of these disorders.

Paediatric autoimmune and autoinflammatory conditions associated with uveitis

Childhood uveitis comprises a collection of heterogenous ocular phenotypes which are associated with a diverse range of childhood autoimmune and autoinflammatory disorders. Of these genetic and/or acquired disorders, juvenile idiopathic arthritis is the most common, affecting 30-80% of children with uveitis. Up to a third of children with uveitis have 'isolated' idiopathic disease and do not have an associated systemic disease which manifests in childhood. However, uveitis may be the presenting manifestation of disease; thus, the apparently well child who presents with uveitis may have isolated idiopathic disease, but they may have an evolving systemic disorder. The diagnosis of most of the associated disorders is reliant on clinical features rather than serological or genetic investigations, necessitating detailed medical history taking and systemic examination. Adequate control of inflammation is key to good visual outcomes, and multidisciplinary care is key to good broader health outcomes.