Understanding immune profiles in ichthyosis may lead to novel therapeutic targets

The role of interleukin-36 in health and disease states

The interleukin (IL)-1 superfamily upregulates immune responses and maintains homeostasis between the innate and adaptive immune systems. Within the IL-1 superfamily, IL-36 plays a pivotal role in both innate and adaptive immune responses. Of the four IL-36 isoforms, three have agonist activity (IL-36α, IL-36β, IL-36γ) and the fourth has antagonist activity (IL-36 receptor antagonist [IL-36Ra]). All IL-36 isoforms bind to the IL-36 receptor (IL-36R). Binding of IL-36α/β/γ to the IL-36R recruits the IL-1 receptor accessory protein (IL-1RAcP) and activates downstream signalling pathways mediated by nuclear transcription factor kappa B and mitogen-activated protein kinase signalling pathways. Antagonist binding of IL-36Ra to IL-36R inhibits recruitment of IL-1RAcP, blocking downstream signalling pathways. Changes in the balance within the IL-36 cytokine family can lead to uncontrolled inflammatory responses throughout the body. As such, IL-36 has been implicated in numerous inflammatory diseases, notably a type of pustular psoriasis called generalized pustular psoriasis (GPP), a chronic, rare, potentially life-threatening, multisystemic skin disease characterised by recurrent fever and extensive sterile pustules. In GPP, IL-36 is central to disease pathogenesis, and the prevention of IL-36-mediated signalling can improve clinical outcomes. In this review, we summarize the literature describing the biological functions of the IL-36 pathway. We also consider the evidence for uncontrolled activation of the IL-36 pathway in a wide range of skin (e.g., plaque psoriasis, pustular psoriasis, hidradenitis suppurativa, acne, Netherton syndrome, atopic dermatitis and pyoderma gangrenosum), lung (e.g., idiopathic pulmonary fibrosis), gut (e.g., intestinal fibrosis, inflammatory bowel disease and Hirschsprung's disease), kidney (e.g., renal tubulointerstitial lesions) and infectious diseases caused by a variety of pathogens (e.g., COVID-19; Mycobacterium tuberculosis, Pseudomonas aeruginosa, Streptococcus pneumoniae infections), as well as in cancer. We also consider how targeting the IL-36 signalling pathway could be used in treating inflammatory disease states.

Targeting IL-36 in Inflammatory Skin Diseases

Interleukin (IL)-36 cytokines are members of the IL-1 superfamily of cytokines. IL-36 cytokines are composed of three agonists (IL-36α, IL-36β, and IL-36γ) and two antagonists (IL-36 receptor antagonist [IL36Ra] and IL-38). These work in innate and acquired immunity and are known to contribute to host defense and to the pathogenesis of autoinflammatory diseases, autoimmune diseases, and infectious diseases. In the skin, IL-36α and IL-36γ are mainly expressed by keratinocytes in the epidermis, although they are also produced by dendritic cells, macrophages, endothelial cells, and dermal fibroblasts. IL-36 cytokines participate in the first-line defense of the skin against various exogenous assaults. IL-36 cytokines play significant roles in the host defense system and in the regulation of inflammatory pathways in the skin, collaborating with other cytokines/chemokines and immune-related molecules. Thus, numerous studies have shown IL-36 cytokines to play important roles in the pathogenesis of various skin diseases. In this context, the clinical efficacy and safety profiles of anti-IL-36 agents such as spesolimab and imsidolimab have been evaluated in patients with generalized pustular psoriasis, palmoplantar pustulosis, hidradenitis suppurativa, acne/acneiform eruptions, ichthyoses, and atopic dermatitis. This article comprehensively summarizes the roles played by IL-36 cytokines in the pathogenesis and pathophysiology of various skin diseases and summarizes the current state of research on therapeutic agents that target IL-36 cytokine pathways.

Dupilumab in the treatment of genodermatosis: A systematic review

Dupilumab interferes with the signaling pathways of IL-4 and IL-13 and is effective in treating atopic dermatitis. Specific genodermatoses, including Netherton syndrome, epidermolysis bullosa pruriginosa, and hyper-IgE syndrome, are Th2 skewed diseases with activation of type 2 inflammation. We performed this systematic review to investigate the therapeutic role of dupilumab in the treatment of genodermatosis. A systematic search was conducted of the PubMed, Embase, Web of Science, and Cochrane databases from inception to December 13, 2021. The review included studies with relevant terms including "dupilumab," "genodermatosis", "Netherton syndrome", "ichthyosis", "epidermolysis bullosa" and "hyper-IgE syndrome". The initial search yielded 2,888 results, of which 28 studies and 37 patients with genodermatosis were enrolled. The assessed genodermatoses included Netherton syndrome, epidermolysis bullosa pruriginosa, hyper-IgE syndrome, Hailey-Hailey disease, and severe eczema associated with genetic disorders. Most of the reported cases showed significant clinical improvement after the initiation of dupilumab treatment without major adverse events. Decreased immunoglobulin E levels and cytokine normalization have also been documented. In conclusion, Dupilumab may have a potential therapeutic role in certain genodermatoses skewed towards T helper 2 (Th2) immunity, including Netherton syndrome, epidermolysis bullosa pruriginosa, hyper-IgE syndrome, Hailey-Hailey disease, and severe eczema associated with some genetic disorders.

Report of two sisters with Netherton syndrome successfully treated with dupilumab and review of the literature

Different monoclonal antibodies have been used for the treatment of Netherton's syndrome (NS); secukinumab (anti-IL17A), infliximab (anti-TNF-α), ustekinumab (anti p40 subunit of IL-12 and IL-23), omalizumab (anti-IgE), and dupilumab (anti-IL4 and IL13). We report two sisters with severe NS who were treated with omalizumab in one and with secukinumab in the other. In view of the therapeutic failure, treatment with dupilumab was started in both sisters. The data were analyzed 16 weeks after starting treatment with dupilumab. Treatment response was assessed using the Severity Scoring Atopic Dermatitis (SCORAD); Eczema Area and Severity Index (EASI); Pruritus Numeric Rating Scale (NSR); Netherton Area Severity Assessment (NASA) and Dermatology Life Quality Index Ichthyosis. All scores were reduced after 16 weeks of treatment with dupilumab in both patients. She maintains improvement after 18 months and 12 months of treatment, respectively. No severe adverse events were reported. Treatment with dupilumab in two sisters with NS and atopic diseases produced a marked cutaneous improvement after a failed attempt with omalizumab and secukinumab. Further studies are needed to determine which biologic therapy is the most effective in NS.

Treatments for Non-Syndromic Inherited Ichthyosis, Including Emergent Pathogenesis-Related Therapy

The term 'inherited ichthyosis' refers to a heterogeneous group of mendelian disorders of cornification that involve the integument with varying degrees of scaling. The management of ichthyosis poses a challenge for most physicians. Treatment options proposed in the literature include moisturizers, topical keratolytics, topical and systemic vitamin D analogues, and topical and systemic retinoids; however, some of these modalities are less reliable than others. Despite the therapeutic impasse imposed by the options above, the emergence of pathogenesis-based treatments along with novel gene therapies appear promising and hold the potential to halt or even revert disorders that arise from single genetic mutations, although research is still quite lacking in this domain. Hence, this review aims to highlight the various treatment modalities available for the management of the cutaneous manifestations of non-syndromic inherited ichthyosis, with an added emphasis on pathogenesis-targeted therapies.

Management of Harlequin Ichthyosis: A Brief Review of the Recent Literature

Harlequin ichthyosis (HI) is a life-threatening genetic disorder that largely affects the skin of infants. HI is the most severe form of the autosomal recessive disorder known as ichthyosis. It is caused by mutations in the A12 cassette (lipid-transporter adenosine triphosphate-binding cassette A12). Neonates affected by this disease are born with specific morphological characteristics, the most prominent of which is the appearance of platelet keratotic scales separated by erythematous fissures. The facial features include eclabium, ectropion, a distinct flattened nose, and dysplastic ears. A common finding among those with HI is impaired skin barrier function. The purpose of the present narrative review is to assess the most recent literature regarding the management of HI. Emphasis is given to surgical management and consultation, to the indications for timing and surgical intervention, to the risks that are presented with surgery, and to the details of the surgical procedure itself. Management of HI requires a multidisciplinary team of experts, and specific guidelines are needed in order for the risks to be minimized and viability to be increased.