The Skin as a Window into Primary Immune Deficiency Diseases: Atopic Dermatitis and Chronic Mucocutaneous Candidiasis

Atypical Localization of Eczema Discriminates DOCK8 or STAT3 Deficiencies from Atopic Dermatitis

PURPOSE

Autosomal recessive dedicator of cytokinesis 8 (DOCK8-/-) and autosomal dominant signal transducer and activator of transcription 3 (STAT3-/+) deficiencies are inborn errors of immunity (IEI) disorders present with the classic features of eczema and create a dilemma during differentiation from atopic dermatitis (AD). Therefore, an appropriate approach is required for eczema to diagnose DOCK8-/- and STAT3-/+ early. Here, we described a set of clinical and immunological variables, including atypical AD localizations and lymphocyte subsets, to differentiate DOCK8-/- or STAT3-/+ from AD.

METHODS

This multicenter study involved 100 patients with DOCK8-/- and STAT3-/+ and moderate/severe AD. We recruited disease manifestations, including detailed localizations of eczema, infections, and allergy. Principle component analysis (PCA) was used to discriminate DOCK8-/- or STAT3-/+ from AD.

RESULTS

There were 43 patients with DOCK8-/-, 23 with STAT3-/+, and 34 with AD. Pneumonia, severe infections, mucocutaneous candidiasis, and skin abscesses were commonly observed in DOCK8 and STAT3 deficiencies. Atypical skin involvement with neonatal rash, retro auricular, axillary, sacral, and genital eczema discriminate DOCK8-/- and STAT3-/+ from AD with high specificity ranges between 73.5 and 94.1% and positive predictive index ranges between 55 and 93.1%. Together with using absolute numbers of CD3+, CD4+, and CD8+ T cells, the combined clinical and laboratory features showed perfect differentiation between DOCK8-/- or STAT3-/+ and AD via PCA.

CONCLUSIONS

The described features can be easily implemented by physicians providing early diagnosis of DOCK8 and STAT3 deficiencies.

Cutaneous Findings in Inborn Errors of Immunity: An Immunologist's Perspective

Cutaneous manifestations are common in patients with inborn errors of immunity (IEI)/primary immunodeficiency and could be due to infections, immune dysregulation, or lymphoproliferative/malign diseases. Immunologists accept some as warning signs for underlying IEI. Herein, we include noninfectious/infectious cutaneous manifestations that we come across in rare IEI cases in our clinic and provide a comprehensive literature review. For several skin diseases, the diagnosis is challenging and differential diagnosis is necessary. Detailed disease history and examination play a vital role in reaching a diagnosis, especially if there is a potential underlying IEI. A skin biopsy is sometimes necessary, especially if we need to rule out inflammatory, infectious, lymphoproliferative, and malignant conditions. Specific and immunohistochemical stainings are particularly important when diagnosing granuloma, amyloidosis, malignancies, and infections like human herpes virus-6, human herpes virus-8, human papillomavirus, and orf. Elucidation of mechanisms of IEIs has improved our understanding of their relation to cutaneous findings. In challenging cases, the immunological evaluation may lead the approach when there is a specific primary immunodeficiency diagnosis or at least help to reduce the number of differential diagnoses. Conversely, the response to therapy may provide conclusive evidence for some conditions. This review raises awareness of concomitant lesions and expands the scope of the differential diagnosis of IEI and the spectrum of skin disease therapy by highlighting frequent forms of IEI-associated cutaneous manifestations. The manifestations given here will guide clinicians to plan for alternative use of diverse therapeutics in a multidisciplinary way for skin diseases.

Autoimmune versus Non-autoimmune Cutaneous Features in Monogenic Patients with Inborn Errors of Immunity

Cutaneous manifestations are one of the most common presentations among patients with inborn errors of immunity (IEI). These skin manifestations are often among the first presenting features in the majority of patients preceding the IEI diagnosis. We studied 521 available monogenic patients with IEI listed in the Iranian IEI registry up to November 2022. We extracted each patient's demographic information, detailed clinical history of cutaneous manifestations, and immunologic evaluations. The patients were then categorized and compared based on their phenotypical classifications provided by the International Union of Immunological Societies. Most patients were categorized into syndromic combined immunodeficiency (25.1%), non-syndromic combined immunodeficiency (24.4%), predominantly antibody deficiency (20.7%), and diseases of immune dysregulation (20.5%). In total, 227 patients developed skin manifestations at a median (IQR) age of 2.0 (0.5-5.2) years; a total of 66 (40.7%) of these patients initially presented with these manifestations. Patients with cutaneous involvement were generally older at the time of diagnosis [5.0 (1.6-8.0) vs. 3.0 (1.0-7.0) years; p = 0.022]. Consanguinity was more common among patients who developed skin disorders (81.4% vs. 65.2%, p < 0.001). The overall skin infection rate and the type of dominant pathogens were significantly different among the IEI patients in different phenotypical classifications (p < 0.001). Atopic presentation, including urticaria, was highly prevalent among patients with congenital defects of phagocytes (p = 0.020). The frequency of eczema was also significantly higher among cases with both syndromic and non-syndromic combined immunodeficiency (p = 0.009). In contrast, autoimmune cutaneous manifestations, including alopecia and psoriasis, were most common in patients with immune dysregulation (p = 0.001) and defects in intrinsic or innate immunity (p = 0.031), respectively. The presence of autoimmune cutaneous complications significantly improved the survival rate of IEI patients (p = 0.21). In conclusion, cutaneous manifestations were observed in nearly 44% of Iranian patients with monogenic IEI. A considerable number of patients with cutaneous involvements developed these disorders as their first manifestation of the disease, which was particularly noticeable in patients with non-syndromic combined immunodeficiency and phagocytic defects. The neglected skin disorders in IEI patients might delay diagnosis, which is generally established within a 3-year interval from the development of skin-related problems. Cutaneous disorders, especially autoimmune features, might indicate a mild prognosis in IEI patients.

Clinical Manifestations of Human Exposure to Fungi

Biological particles, along with inorganic gaseous and particulate pollutants, constitute an ever-present component of the atmosphere and surfaces. Among these particles are fungal species colonizing almost all ecosystems, including the human body. Although inoffensive to most people, fungi can be responsible for several health problems, such as allergic fungal diseases and fungal infections. Worldwide fungal disease incidence is increasing, with new emerging fungal diseases appearing yearly. Reasons for this increase are the expansion of life expectancy, the number of immunocompromised patients (immunosuppressive treatments for transplantation, autoimmune diseases, and immunodeficiency diseases), the number of uncontrolled underlying conditions (e.g., diabetes mellitus), and the misusage of medication (e.g., corticosteroids and broad-spectrum antibiotics). Managing fungal diseases is challenging; only four classes of antifungal drugs are available, resistance to these drugs is increasing, and no vaccines have been approved. The present work reviews the implications of fungal particles in human health from allergic diseases (i.e., allergic bronchopulmonary aspergillosis, severe asthma with fungal sensitization, thunderstorm asthma, allergic fungal rhinosinusitis, and occupational lung diseases) to infections (i.e., superficial, subcutaneous, and systemic infections). Topics such as the etiological agent, risk factors, clinical manifestations, diagnosis, and treatment will be revised to improve the knowledge of this growing health concern.

Atopic Dermatitis-like Genodermatosis: Disease Diagnosis and Management

Eczema is a classical characteristic not only in atopic dermatitis but also in various genodermatosis. Patients suffering from primary immunodeficiency diseases such as hyper-immunoglobulin E syndromes, Wiskott-Aldrich syndrome, immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome, STAT5B deficiency, Omenn syndrome, atypical complete DiGeorge syndrome; metabolic disorders such as acrodermatitis enteropathy, multiple carboxylase deficiency, prolidase deficiency; and other rare syndromes like severe dermatitis, multiple allergies and metabolic wasting syndrome, Netherton syndrome, and peeling skin syndrome frequently perform with eczema-like lesions. These genodermatosis may be misguided in the context of eczematous phenotype. Misdiagnosis of severe disorders unavoidably affects appropriate treatment and leads to irreversible outcomes for patients, which underlines the importance of molecular diagnosis and genetic analysis. Here we conclude clinical manifestations, molecular mechanism, diagnosis and management of several eczema-related genodermatosis and provide accessible advice to physicians.

Epidermal clearance of Candida albicans is mediated by IL-17 but independent of fungal innate immune receptors

IL-17 plays important roles in host defense against Candida albicans at barrier surfaces and during invasive infection. However, the role of IL-17 in host defense after colonization of the epidermis, a main site of C. albicans infection, remains poorly understood. Using a murine model of epicutaneous candidiasis without skin abrasion, we found that skin inflammation triggered by epidermal C. albicans colonization was self-limiting with fungal clearance completed by day 7 after inoculation in wild-type mice or animals deficient in IL-17A or IL-17F. In contrast, marked neutrophilic inflammation in the epidermis and impaired fungal clearance were observed in mice lacking both IL-17A and IL-17F. Clearance of C. albicans was independent of Dectin-1, Dectin-2, CARD9 (caspase-recruitment domain family, member 9), TLR2 (Toll-like receptor 2) and MyD88 in the epidermal colonization model. We found that group 3 innate lymphoid cells (ILC3s) and γδT cells were the major IL-17 producers in the epicutaneous candidiasis model. Analyses of Rag2-/- mice and Rag2-/-Il2rg-/- mice revealed that production of IL-17A and IL-17F by ILC3s was sufficient for C. albicans clearance. Finally, we found that depletion of neutrophils impaired C. albicans clearance in the epidermal colonization model. Taken together, these findings indicate a critical and redundant function of IL-17A and IL-17F produced by ILC3s in host defense against C. albicans in the epidermis. The results also suggest that epidermal C. albicans clearance is independent of innate immune receptors or that these receptors act redundantly in fungal recognition and clearance.

[Combined immunodeficiency due to DOCK8 deficiency. State of the art]

Combinedimmunodeficiency (CID) due to DOCK8 deficiency is an inborn error of immunity (IBD) characterized by dysfunctional T and B lymphocytes; The spectrum of manifestations includes allergy, autoimmunity, inflammation, predisposition to cancer, and recurrent infections. DOCK8 deficiency can be distinguished from other CIDs or within the spectrum of hyper-IgE syndromes by exhibiting profound susceptibility to viral skin infections, associated skin cancers, and severe food allergies. The 9p24.3 subtelomeric locus where DOCK8 is located includes numerous repetitive sequence elements that predispose to the generation of large germline deletions and recombination-mediated somatic DNA repair. Residual production DOCK8 protein contributes to the variable phenotype of the disease. Severe viral skin infections and varicella-zoster virus (VZV)-associated vasculopathy, reflect an essential role of the DOCK8 protein, which is required to maintain lymphocyte integrity as cells migrate through the tissues. Loss of DOCK8 causes immune deficiencies through other mechanisms, including a cell survival defect. In addition, there are alterations in the response of dendritic cells, which explains susceptibility to virus infection and regulatory T lymphocytes that could help explain autoimmunity in patients. Hematopoietic stem cell transplantation (HSCT) is the only curative treatment; it improves eczema, allergies, and susceptibility to infections.

Recent Progress in Traditional Chinese Medicines and Their Mechanism in the Treatment of Allergic Rhinitis

Objective

To conduct a systematic review on the mechanism of action and use of traditional Chinese medicines (TCM) in allergic rhinitis treatment.

Background

Allergic rhinitis (AR) is a type I allergic disease of the immune system induced by immunoglobulin E mediated inflammation and is characterized by sneezing, nasal itching, paroxysmal nasal obstruction, mucosal edema, cough, and rhinorrhea. More than 500 million people have been affected by rhinitis worldwide in the past 20 years, leading to negative effects on health, quality of life, and social relationships. Currently, the trending medicines used in the case of AR include intranasal corticosteroids and oral H1 antihistamines, which are given as combinatorial medicines supplemented with immune therapy. These medications have been found to be very effective in either the short term or long term; however, they have been found to possess some serious side effects. Search Methodology. The information in this article on classical and traditional Chinese medications used to treat AR was derived from original papers and reviews published in Chinese and English language journals. Two Chinese databases (Wanfang and CNKI) and three English databases (Cochrane Library, PubMed, and Embase) were utilized for data gathering.

Results

Traditional Chinese remedies have been identified to influence the production of cytokines such as IL-5 and IL-6, which are key mediators of eosinophilic inflammation, TNF-α, which stimulates TH2 cells at the site of inflammation, and NF-кB, which is required for cytokine and IgE antibody production. TCM has also been shown to be successful in lowering histamine levels, preserving histological changes by decreasing the thickness of the lamina propria, and downregulating the expression of Orai1, STIM1, and TRYC1, showing low expression of Ca⁺² channel proteins.

Conclusion

In this review, we discussed a series of classical, traditional Chinese medications, including Centipeda minima, Scutellaria baicalensis, licorice root (Glycyrrhiza uralensis), and others, as potential antiallergic agents and investigate their in vivo effect upon the production of cytokines and release of histamines for allergic rhinitis treatment.

Inborn errors of immunity manifesting as atopic disorders

Inborn errors of immunity are traditionally best known for enhancing susceptibility to infections. However, allergic inflammation, among other types of immune dysregulation, occurs frequently in patients with inborn errors of immunity. As such, the term primary atopic disorders (PADs) was recently coined to describe the group of heritable monogenic allergic disorders. It is becoming increasingly important for clinicians to recognize that allergic diseases such as food allergy, atopic dermatitis, and allergic asthma are expressions of misdirected immunity, and in patients who present with severe, early-onset, or coexisting allergic conditions, these can be indications of an underlying PAD. Identifying monogenic allergic disease through next-generation sequencing can dramatically improve outcomes by allowing the use of precision-based therapy targeting the patient's underlying molecular defect. It is therefore imperative that clinicians recognize PADs to be able to provide informed therapeutic options and improve patient outcomes. Here, we summarize the clinical features commonly seen with each of the currently known PADs, identify clinical warning signs that warrant assessment for PADs, and lastly, discuss the benefits of timely diagnosis and management of these conditions.

Keratinocyte IL-36 Receptor/MyD88 Signaling Mediates Malassezia-Induced IL-17-Dependent Skin Inflammation

BACKGROUND

Among skin commensal fungi, lipophilic Malassezia species exist on nearly all human skin surfaces. The pathophysiology of Malassezia-associated skin diseases remains poorly understood due in part to the lack of appropriate animal models. Our objective was to investigate the mechanisms underlying Malassezia-induced skin inflammation using a novel murine model that physiologically recapitulates Malassezia skin infection.

METHODS

Mice were inoculated epicutaneously with Malassezia yeasts without barrier disruption and in the absence of external lipid supplementation. Skin inflammation, lesional fungal loads, and expression of cytokines and antimicrobial peptides were evaluated in wild-type and mutant mouse strains.

RESULTS

Malassezia-induced skin inflammation and epidermal thickening were observed on day 4 after inoculation in wild-type mice. High fungal burdens were detected in the cornified layer on day 2 and decreased thereafter with near complete clearance by day 7 after inoculation. Malassezia-induced skin inflammation and fungal clearance by the host were interleukin-17 (IL-17) dependent with contribution of group 3 innate lymphoid cells. Moreover, IL-17-dependent skin inflammation was mediated through IL-36 receptor and keratinocyte MyD88 signaling.

CONCLUSION

Using a new skin infection model, it is shown that Malassezia-induced IL-17- dependent skin inflammation and control of fungal infection are mediated via keratinocyte IL-36 receptor/MyD88 signaling.

Systematic evaluation of nine monogenic autoinflammatory diseases reveals common and disease-specific correlations with allergy-associated features

BACKGROUND

Monogenic autoinflammatory diseases (AID) are caused by mutations in innate immune genes. The effects of these mutations on allergic inflammation are unknown.

OBJECTIVES

We investigated allergic, immunological and clinical phenotypes in FMF (familial Mediterranean fever), CAPS (cryopyrin-associated periodic syndrome), TRAPS (tumour necrosis factor receptor-associated periodic syndrome), HIDS (hyper-IgD syndrome), PAPA (pyogenic arthritis, pyoderma gangrenosum and acne), DADA2 (deficiency of adenosine deaminase 2), HA20 (haploinsufficiency of A20), CANDLE (chronic atypical neutrophilic dermatosis, lipodystrophy, elevated temperature) and SAVI (STING-associated vasculopathy of infancy).

METHODS

In this cross-sectional study, clinical data were assessed in 425 patients with AID using questionnaires and chart reviews. Comparator data were obtained from public databases. Peripheral blood mononuclear cells obtained from 55 patients were stimulated and CD4⁺ cytokine production assessed.

RESULTS

Clinical laboratory features of Type 2 immunity were elevated in CAPS but reduced in most AID, particularly DADA2. Physician-diagnosed allergic diseases were prevalent in multiple AID, including CAPS and DADA2. T helper 2 (Th2) cells were expanded in CAPS, TRAPS and HIDS; Th9 cells were expanded in HA20.

CONCLUSIONS

CAPS is characterised by an enhanced Type 2 signature, whereas FMF and CANDLE are associated with reduced Type 2 responses. DADA2 is associated with reduced Type 2 responses but a high rate of physician-diagnosed allergy. Therefore, NLRP3-driven autoinflammation may promote Type 2 immunity, whereas AID like DADA2 may manifest clinical phenotypes that masquerade as allergic disorders. Further investigations are needed to determine the contribution of autoinflammation to allergic clinical and immunological phenotypes, to improve the treatment of patients with AID.

Inborn errors of immunity with atopic phenotypes: A practical guide for allergists

Inborn errors of immunity (IEI) are a heterogeneous group of disorders, mainly resulting from mutations in genes associated with immunoregulation and immune host defense. These disorders are characterized by different combinations of recurrent infections, autoimmunity, inflammatory manifestations, lymphoproliferation, and malignancy. Interestingly, it has been increasingly observed that common allergic symptoms also can represent the expression of an underlying immunodeficiency and/or immune dysregulation.

Very high IgE levels, peripheral or organ-specific hypereosinophilia, usually combined with a variety of atopic symptoms, may sometimes be the epiphenomenon of a monogenic disease. Therefore, allergists should be aware that severe and/or therapy-resistant atopic disorders might be the main clinical phenotype of some IEI. This could pave the way to target therapies, leading to better quality of life and improved survival in affected patients.

IL-2 Signaling Axis Defects: How Many Faces?

CD25, Signal transducer and activator of transcription 5B (STAT5B) and Forkhead box P3 (FOXP3) are critical mediators of Interleukin-2 (IL-2) signaling pathway in regulatory T cells (Tregs). CD25 (i.e., IL-2 Receptor α) binds with high affinity to IL-2, activating STAT5B-mediated signaling that eventually results in transcription of FOXP3, a master regulator of Treg function. Consequently, loss-of-function mutations in these proteins give rise to Treg disorders (i.e., Tregopathies) that clinically result in multiorgan autoimmunity. Immunodysregulation, Polyendocrinopathy Enteropathy X-linked (IPEX), due to mutations in FOXP3, has historically been the prototype of Tregopathies. This review describes current knowledge about defects in CD25, STAT5B, and FOXP3, highlighting that these disorders both share a common biological background and display comparable clinical features. However, specific phenotypes are associated with each of these syndromes, while certain laboratory findings could be helpful tools for clinicians, in order to achieve a prompt genetic diagnosis. Current treatment strategies will be outlined, keeping an eye on gene editing, an interesting therapeutic perspective that could definitely change the natural history of these disorders.

Mapping Out Autoimmunity Control in Primary Immune Regulatory Disorders

There is a growing understanding of the clinical overlap between primary immune deficiency and autoimmunity. An atypical or treatment-refractory clinical presentation of autoimmunity may in fact signal an underlying congenital condition of primary immune dysregulation (an inborn error of immunity). Detailed profiling of the family history is critical in the diagnostic process and must not be limited to the occurrence of frequent or atypical infections, but additionally should include inquiries into chronic forms of autoimmunity, hyperinflammation, and malignancy. A genetic and a functional diagnostic approach are complementary and nonoverlapping methods of identifying and validating an inborn error of immunity. Extended immune phenotyping of both affected and unaffected family members may provide insight into disease mode of inheritance, penetrance, and secondary inherited or environmentally acquired modifiers. Clinical care of a family with an inborn error of immunity may require local and national expertise in addition to cross-disciplinary care from the disciplines of pediatrics and internal medicine. Physician communication across subspecialties as well as distinct medical institutes can facilitate the appropriate disclosure of genetic testing results toward their prompt incorporation into patient care. Targeted immunomodulation based directly on genetic and functional immune phenotyping has the potential to reduce unnecessary immunosuppression and provide more exacting therapeutic benefit to our patients.

Exploiting solid lipid nanoparticles and nanostructured lipid carriers for drug delivery against cutaneous fungal infections

Several types of cutaneous fungal infections can affect the population worldwide, such as dermatophytosis, cutaneous candidiasis, onychomycosis, and sporotrichosis. However, oral treatments have pronounced adverse effects, making the topical route an alternative to avoid this disadvantage. On the other hand, currently available pharmaceutical forms designed for topical application, such as gels and creams, do not demonstrate effective retention of biomolecules in the upper layers of the skin. An interesting approach to optimise biomolecules' activity in the skin is the use of nanosystems for drug delivery, especially solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), which in the past decade has shown advantages like increased adhesiveness, great occlusive properties and higher biomolecule deposition in stratum corneum when designed for topical application. Considering the demand for more effective therapeutic alternatives and the promising characteristics of SLN and NLC for topical application, the present study sought to gather studies that investigated the potential of using SLN and NLC for the treatment of cutaneous fungal infections. Studies demonstrated that these nanosystems showed optimisation, mostly, of the effectiveness of biomolecules besides other biopharmaceutical properties, in addition to offering potential occlusion and hydration of the applied region.