Persistent Neutrophil Infiltration and Unique Ocular Surface Microbiome Typify Dupilumab-Associated Conjunctivitis in Patients with Atopic Dermatitis

Objective

To elucidate the pathogenesis of dupilumab (Dupixent®)-associated ocular surface disease (DAOSD).

Design

Prospective single-center cohort study.

Subjects

Twenty patients with moderate-to-severe atopic dermatitis (AD) who received dupilumab and 10 age- and sex-matched healthy controls were enrolled in the study.

Methods

The study cohort underwent a thorough slit-lamp and entire-body dermatologic examination. Conjunctival swabs and smears were collected at baseline, 4 and 16 weeks after treatment initiation, and during the conjunctivitis episode. To analyse the ocular surface microbiome, 16S ribosomal RNA sequencing was performed, smears were hematoxylin and eosin stained, and serum cytokines were measured by using a multiplex immunobead assay.

Main Outcome Measures

Composition of ocular surface microbiome and cellular component as well as serum cytokine levels.

Results

Six of the 20 patients with AD developed DAOSD after dupilumab initiation; these patients responded after a delay to treatment as quantified by Eczema Area and Severity Index and Investigator's Global Assessment score. Conjunctival smears showed massive neutrophilic infiltration and serum analysis revealed increased systemic levels of neutrophil-priming proinflammatory cytokines, in particular interleukin-1β and tumor necrosis factor α, in patients with DAOSD compared with those without it. The ocular surface microbiome of patients with DAOSD was characterized by a diverse and persistent microbial colonization, particularly by Acetobacter aceti. In contrast, microbial diversity decreased in patients with AD without DAOSD after the initiation of dupilumab treatment, especially the abundance of Staphylococcus aureus. In vitro experiments substantiated the potential role of the microbiome, showing increased growth of A. aceti and decreased growth of S. aureus in presence of dupilumab.

Conclusions

Persistent neutrophilic infiltration and a unique microbial landscape on the ocular surface associated with elevated levels of systemic proinflammatory cytokines typify DAOSD.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Accumulation of Cytotoxic Skin Resident Memory T Cells and Increased Expression of IL-15 in Lesional Skin of Polymorphic Light Eruption

Patients with polymorphic light eruption (PLE) develop lesions upon the first exposure to sun in spring/summer, but lesions usually subside during season due to the natural (or medical) photohardening. However, these lesions tend to reappear the following year and continue to do so in most patients, suggesting the presence of a disease memory. To study the potential role of skin resident memory T cells (Trm), we investigated the functional phenotype of Trm and the expression of IL-15 in PLE. IL-15 is known to drive Trm proliferation and survival. Multiplex immunofluorescence was used to quantify the expression of CD3, CD4, CD8, CD69, CD103, CD49a, CD11b, CD11c, CD68, granzyme B (GzmB), interferon-gamma (IFN-γ), and IL-15 in formalin-fixed, paraffin-embedded lesional skin samples from PLE patients and healthy skin from control subjects. Unlike the constitutive T cell population in healthy skin, a massive infiltration of T cells in the dermis and epidermis was observed in PLE, and the majority of these belonged to CD8⁺ T cells which express Trm markers (CD69, CD103, CD49a) and produced cytotoxic effector molecules GzmB and IFN-γ. Higher numbers of CD3⁺ T cells and CD11b⁺CD68⁺ macrophages produced IL-15 in the dermis as compared to healthy skin. The dominant accumulation of cytotoxic Trm cells and increased expression of IL-15 in lesional skin of PLE patients strongly indicates the potential role of skin Trm cells in the disease manifestation and recurrence.

Induction of IL-1β and antimicrobial peptides as a potential mechanism for topical dithranol

Topical dithranol is effective in autoimmune conditions like alopecia areata, inducing hair regrowth in a high percentage of cases. Exact mechanisms of dithranol in alopecia areata, with seemingly healthy epidermis besides altered hair follicles, are not well understood. To better understand dithranol's mechanisms on healthy skin, we analysed its effect on normal murine as well as xenografted human skin. We found a strong increase in mRNA expression of anti-microbial peptides (AMPs) (eg Lcn2, Defb1, Defb3, S100a8, S100a9), keratinocyte differentiation markers (eg Serpinb3a, Flg, Krt16, Lce3e) and inflammatory cytokines (eg Il1b and Il17) in healthy murine skin. This effect was paralleled by inflammation and disturbed skin barrier, as well as an injury response resulting in epidermal hyperproliferation, as observed in murine and xenografted adult human skin. This contact response and disturbed barrier induced by dithranol might lead via a vicious loop between AMPs such as S100a8/a9 (that led to skin swelling itself after topical application) and cytokines such as IL-1β to an immune suppressive environment in the skin. A better understanding of the skin's physiologic response to dithranol may open up new avenues for the establishment of novel therapeutics (including AMP-related/interfering molecules) for certain skin conditions, such as alopecia areata.

Potential of Skin Microbiome, Pro- and/or Pre-Biotics to Affect Local Cutaneous Responses to UV Exposure

The human skin hosts innumerable microorganisms and maintains homeostasis with the local immune system despite the challenges offered by environmental factors such as ultraviolet radiation (UVR). UVR causes cutaneous alterations such as acute (i.e., sunburn) and chronic inflammation, tanning, photoaging, skin cancer, and immune modulation. Phototherapy on the other hand is widely used to treat inflammatory skin diseases such as psoriasis, atopic dermatitis, polymorphic light eruption and graft-versus-host disease (GvHD), as well as neoplastic skin diseases such as cutaneous T cell lymphoma, among others. Previous work has addressed the use of pro- and pre-biotics to protect against UVR through anti-oxidative, anti-inflammatory, anti-aging, anti-carcinogenic and/or pro-and contra-melanogenic properties. Herein, we discuss and share perspectives of the potential benefits of novel treatment strategies using microbes and pro- and pre-biotics as modulators of the skin response to UVR, and how they could act both for protection against UVR-induced skin damage and as enhancers of the UVR-driven therapeutic effects on the skin.

Dithranol targets keratinocytes, their crosstalk with neutrophils and inhibits the IL-36 inflammatory loop in psoriasis

Despite the introduction of biologics, topical dithranol (anthralin) has remained one of the most effective anti-psoriatic agents. Serial biopsies from human psoriatic lesions and both the c-Jun/JunB and imiquimod psoriasis mouse model allowed us to study the therapeutic mechanism of this drug. Top differentially expressed genes in the early response to dithranol belonged to keratinocyte and epidermal differentiation pathways and IL-1 family members (i.e. IL36RN) but not elements of the IL-17/IL-23 axis. In human psoriatic response to dithranol, rapid decrease in expression of keratinocyte differentiation regulators (e.g. involucrin, SERPINB7 and SERPINB13), antimicrobial peptides (e.g. ß-defensins like DEFB4A, DEFB4B, DEFB103A, S100 proteins like S100A7, S100A12), chemotactic factors for neutrophils (e.g. CXCL5, CXCL8) and neutrophilic infiltration was followed with much delay by reduction in T cell infiltration. Targeting keratinocytes rather than immune cells may be an alternative approach in particular for topical anti-psoriatic treatment, an area with high need for new drugs.

Molecular Profiling of Keratinocyte Skin Tumors Links Staphylococcus aureus Overabundance and Increased Human β-Defensin-2 Expression to Growth Promotion of Squamous Cell Carcinoma

The skin microbiota plays a prominent role in health and disease; however, its contribution to skin tumorigenesis is not well understood. We comparatively assessed the microbial community compositions from excision specimens of the main human non-melanoma skin cancers, actinic keratosis (AK), squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Keratinocyte skin tumors are characterized by significantly different microbial community compositions, wherein AK and SCC are more similar to each other than to BCC. Notably, in SCC, which represents the advanced tumor entity and frequently develops from AK, overabundance of Staphylococcus aureus, a known skin pathogen, was noted. Moreover, S. aureus overabundance was significantly associated with increased human β-defensin-2 (hBD-2) expression in SCC. By challenging human SCC cell lines with S. aureus, a specific induction of hBD-2 expression and increased tumor cell growth was seen. Increased proliferation was also induced by directly challenging SCC cells with hBD-2. Together, our data indicate that a changed microbial community composition in SCC, specified by S. aureus overabundance, might promote tumor cell growth via modulation of hBD-2 expression.

Skin Microbiome Modulates the Effect of Ultraviolet Radiation on Cellular Response and Immune Function

The skin is colonized by a diverse microbiome intricately involved in various molecular and cellular processes within the skin and beyond. UV radiation is known to induce profound changes in the skin and modulate the immune response. However, the role of the microbiome in UV-induced immune suppression has been overlooked. By employing the standard model of contact hypersensitivity (using germ-free mice) we found diminished UV-induced systemic immune suppression in the presence of microbiome. Upon UV exposure, we found enhanced epidermal hyperplasia and neutrophilic infiltration in the presence and enhanced numbers of mast cells and monocyte or macrophages in the absence of microbiome. Transcriptome analysis revealed a predominant expression of cytokine genes related to pro-inflammatory milieu in the presence versus immunosuppressive milieu (with increased interleukin-10) in the absence of microbiome. Collectively, microbiome abrogates the immunosuppressive response to UV by modulating gene expression and cellular microenvironment of the skin.

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Epidermal and immune response to UV is dependent on skin microbiome

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Increased neutrophilic infiltration and expression of IL-1β in SPF mice after UV-R

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Elevated macrophage infiltration and expression of IL-10 in GF mice after UV-R

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Skin microbiome diminishes UV-induced immune suppression to contact allergen DNFB

Polymorphic light eruption and IL-1 family members: any difference with allergic contact dermatitis?

Polymorphic light eruption (PLE) is described as a delayed-type hypersensitivity reaction (DTHR) toward a de novo light-induced antigen, yet to be identified. In effect, the inflammatory pathways of PLE and allergic contact dermatitis (ACD) share common patterns in terms of the mediators involved from the innate and adaptive immune system participating in the DTHR. As we have previously highlighted the role of interleukin (IL)-1 family members in ACD, we hypothesised that the same mediators could have similar functions in PLE. Our research aimed to assess the expression of certain IL-1family members in PLE patients vs. controls, and to compare it with ACD. The study population comprised 17 patients with PLE, 5 affected by ACD and 10 healthy controls in the same age range. Lesional and healthy skin samples were collected respectively from patients and donors. IL-36α, IL-36β, IL-36γ, IL-36 receptor antagonist (Ra), IL-1β, IL-33 gene and protein expressions were evaluated through RT-PCR and immunohistochemistry. Circulating proteins in the PLE patients were analysed by using western blot. The IL-36γ gene expression was significantly increased in PLE lesions compared to that in healthy controls and ACD lesions (***p < 0.001; ##p < 0.01 respectively), whereas the other analyzed ILs were more expressed in ACD. Immunohistochemical analysis revealed that IL-36α and IL-36γ protein levels were increased in PLE lesions compared to those of the healthy samples (***p < 0.001). Furthermore the IL-36γ plasma level was increased in PLE patients vs. controls (*p < 0.05). Our findings indicate that the IL-1 family pro-inflammatory members are increased in PLE with distinct differences from those in ACD, in particular with regard to IL-36γ mRNA regulation. Their role as activators of the local, and perhaps systemic, immune response, or as inhibitors of the immune tolerance machinery, needs further investigation.

A Perspective on the Interplay of Ultraviolet-Radiation, Skin Microbiome and Skin Resident Memory TCRαβ+ Cells

The human skin is known to be inhabited by diverse microbes, including bacteria, fungi, viruses, archaea, and mites. This microbiome exerts a protective role against infections by promoting immune development and inhibiting pathogenic microbes to colonize skin. One of the factors having an intense effect on the skin and its resident microbes is ultraviolet-radiation (UV-R). UV-R can promote or inhibit the growth of microbes on the skin and modulate the immune system which can be either favorable or harmful. Among potential UV-R targets, skin resident memory T cells (T_RM) stand as well positioned immune cells at the forefront within the skin. Both CD4⁺ or CD8⁺ αβ T_RM cells residing permanently in peripheral tissues have been shown to play prominent roles in providing accelerated and long-lived specific immunity, tissue homeostasis, wound repair. Nevertheless, their response upon UV-R exposure or signals from microbiome are poorly understood compared to resident TCRγδ cells. Skin T_RM survive for long periods of time and are exposed to innumerable antigens during lifetime. The interplay of T_RM with skin residing microbes may be crucial in pathophysiology of various diseases including psoriasis, atopic dermatitis and polymorphic light eruption. In this article, we share our perspective about how UV-R may directly shape the persistence, phenotype, specificity, and function of skin T_RM; and moreover, whether UV-R alters barrier function, leading to microbial-specific skin T_RM, disrupting the healthy balance between skin microbiome and skin immune cells, and resulting in chronic inflammation and diseased skin.

Desired response to phototherapy vs photoaggravation in psoriasis: what makes the difference?

Psoriasis commonly responds beneficially to UV radiation from natural sunlight or artificial sources. Therapeutic mechanisms include the proapoptotic and immunomodulating effects of UV, affecting many cells and involving a variety of pro- and anti-inflammatory cytokines, downregulating the Th17/IL-23 response with simultaneous induction of regulatory immune cells. However, exposure to UV radiation in a subset of psoriasis patients leads to exacerbation of the disease. We herein shed light on the predisposing factors of photosensitive psoriasis, including genetics (such as HLA-Cw*0602 or CARD14), gender and coexisting photodermatoses such as polymorphic light eruption (PLE) in the context of potential molecular mechanisms behind therapeutic photoresponsiveness or photoaggravation. UV-induced damage/pathogen-associated molecular patterns, damage to self-coding RNA (signalling through Toll-like receptors), certain antimicrobial peptides and/or inflammasome activation may induce innate immunity, leading to psoriasis at the site of UV exposure when there is concomitant, predisposing resistance against UV-induced suppression of the adaptive immune response (like in PLE) that otherwise would act to reduce psoriasis.

Microbial elements as the initial triggers in the pathogenesis of polymorphic light eruption?

The primary trigger of polymorphic light eruption (PLE) remains to be uncovered. We hypothesize that PLE may be initiated by elements resulting from UV‐induced damage to microbial communities of the skin, leading to a cascade of events eventually resulting in the skin rash of the disease. One mechanism by which epidermal injury by UV radiation could trigger PLE are danger signals such as damage or pathogen associated molecular patterns DAMP/PAMPs or commensal‐associated molecular patterns (CAMPs). Such triggers could be produced due to UV‐induced stress on microbial communities of the skin and exacerbate inflammatory responses by inducing the innate immune system through antimicrobial peptides (AMPs) such as psoriasin, RNase7, HBD‐2 and LL‐37. These AMPs also actively take part in initiating adaptive immunity. That signals derived from microbial rather than human elements may initiate PLE is supported by series of observations, including the PLE‐protective effect of topically applied microbial‐derived DNA repair enzymes.

Unique profile of antimicrobial peptide expression in polymorphic light eruption lesions compared to healthy skin, atopic dermatitis, and psoriasis

Background

Polymorphic light eruption (PLE) has been attributed to type IV, most likely delayed‐type hypersensitivity response (adaptive immunity) but little is known on innate immunity, especially antimicrobial peptides (AMPs) in the disease. Abnormalities in AMP expression have been linked to pathological skin conditions such as atopic dermatitis (AD) and psoriasis.

Methods

Antimicrobial peptide profiling was carried out in PLE skin samples (n,12) compared with that of healthy (n,13), atopic (n,6), and psoriatic skin (n,6).

Results

Compared to healthy skin, we observed increased expression of psoriasin and RNAse7 (both mostly in stratum granulosum of the epidermis), HBD‐2 (in the cellular infiltrate of the dermis), and LL37 (mostly in and around blood vessels and glands) in PLE lesional skin, a similar expression profile as present in psoriatic skin and different to that of AD (with little or no expression of psoriasin, RNAse7, HBD‐2, and LL37). HBD‐3 was downregulated in PLE compared to its high expression in the epidermis and dermis of healthy skin, AD, and psoriasis.

Conclusion

The unique profile of differentially expressed AMPs in PLE implies a role in the pathophysiology of the disease, possibly directly or indirectly linked to the microbiome of the skin.

The Skin Microbiome: Is It Affected by UV-induced Immune Suppression?

Human skin apart from functioning as a physical barricade to stop the entry of pathogens, also hosts innumerable commensal organisms. The skin cells and the immune system constantly interact with microbes, to maintain cutaneous homeostasis, despite the challenges offered by various environmental factors. A major environmental factor affecting the skin is ultraviolet radiation (UV-R) from sunlight. UV-R is well known to modulate the immune system, which can be both beneficial and deleterious. By targeting the cells and molecules within skin, UV-R can trigger the production and release of antimicrobial peptides, affect the innate immune system and ultimately suppress the adaptive cellular immune response. This can contribute to skin carcinogenesis and the promotion of infectious agents such as herpes simplex virus and possibly others. On the other hand, a UV-established immunosuppressive environment may protect against the induction of immunologically mediated skin diseases including some of photodermatoses such as polymorphic light eruption. In this article, we share our perspective about the possibility that UV-induced immune suppression may alter the landscape of the skin’s microbiome and its components. Alternatively, or in concert with this, direct UV-induced DNA and membrane damage to the microbiome may result in pathogen associated molecular patterns (PAMPs) that interfere with UV-induced immune suppression.

Adrenal and renal metastases from follicular thyroid cancer

Patients with differentiated thyroid cancer may have asymptomatic involvement of renal and/or adrenal gland, particularly if they are elderly and have associated metastases to other organs, which may remain undetected if these patients are not subjected to radioiodine treatment. Our experience also emphasises the role of routine post-radioiodine therapy whole body scan with high degree of clinical suspicion, which may reveal lesions otherwise not discernable in low dose whole body scan. All suspicious lesions should be subjected to structural imaging like ultrasound, CT or MRI for confirmation. In this setting, the role of radioiodine therapy is primarily aimed at palliation that might prolong their survival, probably reduce further spread and thus overall improve the quality of life.