Dupilumab-associated ocular surface disease is characterized by a shift from Th2/Th17 toward Th1/Th17 inflammation

BACKGROUND

Dupilumab is used for the treatment of atopic dermatitis (AD). Approximately one third of AD patients develop a dupilumab-associated ocular surface disease (DAOSD), of which the pathomechanism is poorly understood. This study aimed at investigating inflammatory markers in tear fluids of patients on dupilumab therapy.

METHODS

Tear fluids were collected from AD patients with DAOSD (ADwDAOSD), AD patients without DAOSD (ADw/oDAOSD), and non-AD patients before and during dupilumab therapy, and analyzed using a specialized proteomic approach quantifying inflammatory markers. The ocular surface microbiome was determined by next generation sequencing technology.

RESULTS

Upon dupilumab therapy, an upregulation of 31 inflammatory markers was observed in DAOSD tear fluids compared to baseline in AD patients. While IL-12B was upregulated in both ADwDAOSD and ADw/oDAOSD groups, the pattern of inflammatory markers significantly differed between groups and over time. In the ADwDAOSD group, a shift from a mixed Th2/Th17 pattern at baseline toward a Th1/Th17 profile under dupilumab was observed. Furthermore, an upregulation of remodeling and fibrosis markers was seen in DAOSD. Semantic map and hierarchical cluster analyses of baseline marker expression revealed four clusters distinguishing between AD and non-AD as well as ADwDAOSD and ADw/oDAOSD patient groups. In a pilot study, dupilumab therapy was associated with a decrease in richness of the ocular surface microbiome.

CONCLUSIONS

DAOSD is characterized by a Th1/Th17 cytokine profile and an upregulation of markers known to promote remodeling and fibrosis. The expression pattern of inflammatory markers in tear fluids at baseline might serve as a prognostic factor for DAOSD.

Adverse events from topical corticosteroid use in chronic hand eczema - Findings from the Danish Skin Cohort

Background

Topical corticosteroids (TCS) are used to treat most patients with chronic hand eczema (CHE), but knowledge about TCS-related adverse events in CHE is limited.

Objectives

To investigate patient-reported adverse events to TCS in CHE patients.

Methods

Data on adverse events related to TCS use in patients with CHE were analyzed from the Danish Skin Cohort; a prospective survey of a hospital cohort. We assessed patients' knowledge about TCS use and adverse event risks, and preference of TCS versus a nonsteroidal topical alternative.

Results

Of 724 adults with CHE (64.0% women; mean age 57.5 [standard deviation 12.8] years), 64.1% reported skin atrophy, 41.4% cracks/fissures, 23.9% bleeding, 45.9% pain/stinging sensation, 40.0% reduced hand dexterity, and 40.2% worsening of CHE signs or symptoms from using TCS. We observed CHE-severity-dependent associations (all groups; P < .0001). Most patients (76.4%) would prefer a nonsteroidal option, 10.9% were neutral/indifferent, and 12.7% would prefer TCS for CHE. The median numerical rating scale-score (ranging from 0 to 10) was 10 (interquartile range 6-10) for preferring a nonsteroidal topical treatment.

Limitations

Differences across TCS formulations were unexplored.

Conclusion

TCS-related cutaneous adverse events were common. There is a desire from patients for novel steroid-free topical alternatives for CHE treatment.

UCRAID (Ukrainian Citizen and refugee electronic support in Respiratory diseases, Allergy, Immunology and Dermatology) action plan

Eight million Ukrainians have taken refuge in the European Union. Many have asthma and/or allergic rhinitis and/or urticaria, and around 100,000 may have a severe disease. Cultural and language barriers are a major obstacle to appropriate management. Two widely available mHealth apps, MASK-air® (Mobile Airways Sentinel NetworK) for the management of rhinitis and asthma and CRUSE® (Chronic Urticaria Self Evaluation) for patients with chronic spontaneous urticaria, were updated to include Ukrainian versions that make the documented information available to treating physicians in their own language. The Ukrainian patients fill in the questionnaires and daily symptom-medication scores for asthma, rhinitis (MASK-air) or urticaria (CRUSE) in Ukrainian. Then, following the GDPR, patients grant their physician access to the app by scanning a QR code displayed on the physician's computer enabling the physician to read the app contents in his/her own language. This service is available freely. It takes less than a minute to show patient data to the physician in the physician's web browser. UCRAID-developed by ARIA (Allergic Rhinitis and its Impact on Asthma) and UCARE (Urticaria Centers of Reference and Excellence)-is under the auspices of the Ukraine Ministry of Health as well as European (European Academy of Allergy and Clinical immunology, EAACI, European Respiratory Society, ERS, European Society of Dermatologic Research, ESDR) and national societies.

Proteomics of immune cells from liver tumors reveals immunotherapy targets

Elucidating the mechanisms by which immune cells become dysfunctional in tumors is critical to developing next-generation immunotherapies. We profiled proteomes of cancer tissue as well as monocyte/macrophages, CD4⁺ and CD8⁺ T cells, and NK cells isolated from tumors, liver, and blood of 48 patients with hepatocellular carcinoma. We found that tumor macrophages induce the sphingosine-1-phospate-degrading enzyme SGPL1, which dampened their inflammatory phenotype and anti-tumor function in vivo. We further discovered that the signaling scaffold protein AFAP1L2, typically only found in activated NK cells, is also upregulated in chronically stimulated CD8⁺ T cells in tumors. Ablation of AFAP1L2 in CD8⁺ T cells increased their viability upon repeated stimulation and enhanced their anti-tumor activity synergistically with PD-L1 blockade in mouse models. Our data reveal new targets for immunotherapy and provide a resource on immune cell proteomes in liver cancer.

PPAR-γ regulates the effector function of human T helper 9 cells by promoting glycolysis

T helper 9 (T_H9) cells promote allergic tissue inflammation and express the type 2 cytokines, IL-9 and IL-13, as well as the transcription factor, PPAR-γ. However, the functional role of PPAR-γ in human T_H9 cells remains unknown. Here, we demonstrate that PPAR-γ drives activation-induced glycolysis, which, in turn, promotes the expression of IL-9, but not IL-13, in an mTORC1-dependent manner. In vitro and ex vivo experiments show that the PPAR-γ-mTORC1-IL-9 pathway is active in T_H9 cells in human skin inflammation. Additionally, we find dynamic regulation of tissue glucose levels in acute allergic skin inflammation, suggesting that in situ glucose availability is linked to distinct immunological functions in vivo. Furthermore, paracrine IL-9 induces expression of the lactate transporter, MCT1, in T_H cells and promotes their aerobic glycolysis and proliferative capacity. Altogether, our findings uncover a hitherto unknown relationship between PPAR-γ-dependent glucose metabolism and pathogenic effector functions in human T_H9 cells.

Comorbidities in lichen planus by phenome-wide association study in two biobank population cohorts

BACKGROUND

Lichen planus (LP) is a relatively frequent mucocutaneous inflammatory disease affecting the skin, skin appendages and mucosae, including oral mucosae, and less frequently the anogenital area, conjunctivae, oesophagus or larynx.

OBJECTIVES

To estimate the association of LP, with emphasis on dermatological and gastrointestinal conditions, in two large independent population cohorts.

MATERIALS AND METHODS

We performed a phenome-wide association study (PheWAS) and examined conditions associated with LP in two unrelated cohorts, i.e. the multicentre, community-based UK Biobank (UKB: 501 381 controls; 1130 LP subjects) and the healthcare-associated Penn Medicine BioBank (PMBB; 42 702 controls; 764 LP subjects). The data were analysed in 2021. The 'PheWAS' R package was used to perform the PheWAS analyses and Bonferroni correction was used to adjust for multiple testing. Odds ratios (ORs) were adjusted for age, sex and body mass index.

RESULTS

In the UKB, PheWAS revealed 133 phenome codes (PheCodes) significantly associated with LP and most of them were confirmed in PMBB. Dermatological and digestive PheCodes were the most abundant: 29 and 34 of these disorders, respectively, were significantly overrepresented in LP individuals from both cohorts. The 29 dermatological and 12 oral disorders were often highly enriched, whereas hepatic, gastric, oesophageal and intestinal PheCodes displayed ORs in the range of 1·6-4·5. Several autoimmune disorders also exhibited OR > 5 in both cohorts.

CONCLUSIONS

PheWAS in two large unrelated cohorts identified previously unknown comorbidities and may support clinical counselling of patients with LP. What is already known about this topic? Lichen planus (LP) is known to affect the skin, skin appendages and mucosae, including oral mucosae, and less frequently the anogenital area, conjunctivae, oesophagus or larynx. What does this study add? Our data provide the most comprehensive collection of associated dermatological, digestive and autoimmune disorders to date. Our findings are expected to be useful for the evaluation and management of patients with LP.

Inhibition of melanoma cell-intrinsic Tim-3 stimulates MAPK-dependent tumorigenesis

T-cell immunoglobulin and mucin domain 3 (Tim-3) is an immune checkpoint receptor that dampens effector functions and causes terminal exhaustion of cytotoxic T-cells. Tim-3 inhibitors are under investigation in immuno-oncology (IO) trials, because blockade of T-cell-Tim-3 enhances antitumor immunity. Here, we identify an additional role for Tim-3 as a growth-suppressive receptor intrinsic to melanoma cells. Inhibition of melanoma cell-Tim-3 promoted tumor growth in both immunocompetent and immunocompromised mice, while melanoma-specific Tim-3 overexpression attenuated tumorigenesis. Antibody (Ab)-mediated Tim-3 blockade inhibited growth of immunogenic murine melanomas in T-cell-competent hosts, consistent with established antitumor effects of T-cell Tim-3 inhibition. In contrast, Tim-3 Ab administration stimulated tumorigenesis of both highly and lesser immunogenic murine and human melanomas in T-cell-deficient mice, confirming growth-promoting effects of melanoma-Tim-3 antagonism. Melanoma-Tim-3 activation suppressed, while its blockade enhanced, phosphorylation of pro-proliferative downstream mitogen-activated protein kinase (MAPK) signaling mediators. Finally, pharmacologic MAPK inhibition reversed unwanted Tim-3 Ab-mediated tumorigenesis in T-cell-deficient mice and promoted desired antitumor activity of Tim-3 interference in T-cell-competent hosts. These results identify melanoma-Tim-3 blockade as a mechanism that antagonizes T-cell-Tim-3-directed IO therapeutic efficacy. They further reveal MAPK targeting as a combination strategy for circumventing adverse consequences of unintended melanoma-Tim-3 inhibition.

Transient injection site reaction to alirocumab during immune system activation: a case series

Background

Injection site reactions (ISRs) are known side effects of the proprotein convertase subtilisin kexin 9 (PCSK9) inhibitor alirocumab. Transient ISR to alirocumab after a long phase of good tolerability have not been reported previously.

Case summary

A 55-year-old woman (Patient 1) and a 77-year-old man (Patient 2) were treated with alirocumab for the management of dyslipidaemia. Both patients tolerated the treatment without side effects for 7 and 2 months, respectively. After an upper respiratory tract infection in Patient 1 and a first COVID-19 vaccination in Patient 2, both patients suddenly developed ISR with erythema, calor, and itching upon 2 (Patient 1) and 1 (Patient 2) subsequent injection(s), respectively. Symptoms resolved with local steroids, oral antihistamines, and cooling. After termination of the presumed immune system activated state, alirocumab was well tolerated again in both patients without recurrence of any ISR upon repeated applications.

Discussion

These are the first cases to report transient ISR to a PCSK9 inhibitor, possibly triggered by activation of the immune system, after prolonged good tolerability. Based on the transient and benign nature of the reaction, such patients should be encouraged to continue supervised treatment, as tolerability may return after resolution of the pro-inflammatory state.

T cells in the skin: lymphoma and inflammatory skin disease

T cells are established contributors to the pathogenesis of atopic dermatitis (AD) and psoriasis, yet whether they are the key drivers or simply unwitting participants remains incompletely understood. Conversely, malignant T cells are the undisputed culprits of cutaneous T cell lymphoma (CTCL), a group of diseases that share key clinical, histopathological and molecular features with inflammatory skin disease (ISD). Here, we compare the pathogenesis of ISD and CTCL and discuss the resulting insights. Recurrent, skin-limited disease implicates skin-resident T cells (T_RM) in both ISD and CTCL. In CTCL, malignant T cells recruit benign T cells into inflammatory skin lesions, a disease-amplifying function also proposed for pathogenic T cells in ISD. Mechanistically, cytokines produced by malignant T cells in CTCL and by pathogenic T cells in ISD, respectively, are likely both necessary and sufficient to drive skin inflammation and pruritus, which in turn promotes skin barrier dysfunction and dysbiosis. Therapies for ISD target T cell effector functions but do not address the chronicity of disease while treatments for CTCL target malignant T cells but not primarily the symptoms of the disease. By integrating our understanding of ISD and CTCL, important insights into pathogenesis and therapy can be made which may improve the lives of sufferers of both disease groups.

The Activation Pattern of Drug-Reacting T Cells Has an Impact on the Clinical Picture of Hypersensitivity Reactions

Rationale

β-lactam antibiotics cause drug hypersensitivity reactions (DHR) with various clinical pictures from minor affections like maculopapular exanthema (MPE) and urticaria to severe cutaneous adverse reactions and anaphylaxis. Currently, two different reactivity patterns have been shown to initiate an immune reaction by activating T cells—the hapten concept and the pharmacological interaction with immune receptor (p–i) concept.

Objectives

In this study, the relationship between the reactivity pattern of drug-reacting T cells of drug allergic patients and their clinical picture has been investigated.

Findings

Drug-reacting T-cell clones (TCCs) were isolated from patients hypersensitive to β-lactams. Analysis of their reactivity pattern revealed an exclusive use of the hapten mechanism for patients with immediate reactions and for patients of MPE. In patients suffering from drug reactions with eosinophils and systemic symptoms, a severe DHR, analysis of isolated drug-reacting TCC identified the p–i concept as the unique mechanism for T-cell activation.

Conclusions

The results show a shift from hapten pattern in mild allergic reactions to p–i pattern in severe life-threatening allergic reactions. They strongly argue against the current preclinical risk evaluation of new drugs based on the ability to form haptens.

Effect of topical application of platelet-rich plasma on chronic venous leg ulcerations

Wound products that reliably support healing of chronic leg ulcers remain a huge unmet need in clinical practice. Due to the lack of standardized comparable protocols and different systems for platelet-rich plasma (PRP) preparation, there is limited data on healing rates in chronic venous ulcers. In our case series with a total of seven chronic leg ulcers in four patients, we investigated the healing rates based on standardized digital photographs of chronic venous ulcers after application of topical PRP using a digital imaging software. In 5 out of 7 ulcers, the PRP-treated wound half showed faster healing as compared the control half of the wound. In this case series, PRP-treated sides of chronic venous leg ulcers showed a tendency for accelerated healing as compared to nontreated collateral wound side. Our data support the evaluation of topical PRP treatment in the management of chronic venous leg ulcers.

IL-12 regulates type 3 immunity through interfollicular keratinocytes in psoriasiform inflammation

[Figure: see text].

Long-Term Effectiveness and Drug Survival of Apremilast in Treating Psoriasis: A Real-World Experience

BACKGROUND

Apremilast is an oral phosphodiesterase 4 (PDE4) inhibitor used for the treatment of moderate to severe psoriasis. Long-term data on the effectiveness and drug survival of patients treated with apremilast are limited.

OBJECTIVE

The aim of this study was to analyze the characteristics, effectiveness, and drug survival of patients treated with apremilast in a real-world setting.

METHODS

We conducted a retrospective cohort study of patients with psoriasis who received at least 1 dose of apremilast between 2015 and 2018. We documented sex; age; type, duration, and severity (using Psoriasis Area Severity Index [PASI] and Dermatology Life Quality Index [DLQI]) of psoriasis; comorbidities; previous treatment modalities; adverse events; and reasons for therapy discontinuation. For drug survival, estimates and efficacy analysis with Kaplan-Meier statistics were used.

RESULTS

The drug survival rate of the 93 reviewed patients was 69.5% at 6 months, 34.7% at 12 months, and 25.8% at 24 months after initiating therapy. The median survival duration was 8.0 months. Therapy was discontinued in 66.6 and 27.8% due to loss of efficacy and adverse events, respectively. At 24 months, 35.9% had achieved PASI75 response and 23.7% had achieved PASI90 response. Most observed adverse events were gastrointestinal issues, weight loss, and headache.

CONCLUSIONS

Apremilast is an effective and well-tolerated therapy for patients with moderate to severe psoriasis, especially for patients with difficult-to-treat locations and/or contraindications to other biologics. Furthermore, apremilast was used for patients with a history of nonresponse to biologics and was favored for patients with relatively low PASI (<10) and a high DLQI.

The Concept of Pathogenic TH2 Cells: Collegium Internationale Allergologicum Update 2021

T helper (TH) cells have evolved into distinct subsets that mediate specific immune responses to protect the host against a myriad of infectious and noninfectious challenges. However, if dysregulated, TH-cell subsets can cause inflammatory disease. Emerging evidence now suggests that human allergic disease is caused by a distinct subpopulation of pathogenic TH2 cells. Pathogenic TH2 cells from different type-2-driven diseases share a core phenotype and show overlapping functional attributes. The unique differentiation requirements, activating signals, and metabolic characteristics of pathogenic TH2 cells are just being discovered. A better knowledge of this particular TH2 cell population will enable the specific targeting of disease-driving pathways in allergy. In this review, we introduce a rational for classifying TH cells into distinct subsets, discuss the current knowledge on pathogenic TH2 cells, and summarize their involvement in allergic diseases.

Prurigo Pigmentosa: Demographics and Characteristics in 14 Caucasian Patients

BACKGROUND

Prurigo pigmentosa (PP) is an inflammatory dermatosis typically reported in young Asian women and characterized by recurrent papulovesicular lesions resolving with a postinflammatory reticulated hyperpigmentation.

METHODS

We have included all consecutive patients with PP diagnosed in our tertiary center between 2013 and 2020. The clinical information was retrospectively collected from medical records.

RESULTS

We identified 14 patients with PP. The median age at the time of diagnosis was 29.5 years (range 17-43 years), while the female-to-male ratio was 13:1. Diagnostic delay varied from 10 days to 10 years (mean of 25 months). Light microscopy studies consistently showed presence of a lymphohistiocytic infiltrate in combination in 40% of cases with neutrophils. Interface changes were found in 60% of cases. In 6 (43%) of 14 cases, there was a chronological relationship between the starting of a new diet and the development of the first flares. Treatment with doxycycline in 9 patients resulted in a complete regression of the lesions.

LIMITATION

This was a retrospective study in a tertiary referral hospital.

CONCLUSIONS

Our observations indicate that PP is not so rare in Europe as previously thought and is often diagnosed after a long delay. Demographics, clinical characteristics and triggering factors in Caucasian patients are similar to those described in the Asian population. Diagnosis is based on the peculiar recurrent course and distinctive clinicopathological features. Tetracyclines represent the first-line therapy in PP.

Case Report: Combination of Omalizumab and Dupilumab for Recalcitrant Bullous Pemphigoid

Bullous pemphigoid (BP) is a blistering autoimmune skin disease. Omalizumab, a monoclonal antibody directed to IgE, showed a beneficial effect in treatment of recalcitrant BP in case series. More recently, dupilumab, an interleukin (IL)-4-receptor alpha antagonist, also showed promising preliminary results. We describe a patient with refractory BP who showed a complete response to a combination therapy with omalizumab and dupilumab.

Topical Treatment of Psoriasis Vulgaris: The Swiss Treatment Pathway

Topical treatment is crucial for the successful management of plaque psoriasis. Topicals are used either as a stand-alone therapy for mild psoriasis or else in combination with UV or systemic treatment for moderate-to-severe disease. For the choice of a suitable topical treatment, the formulation matters and not just the active substances. This expert opinion paper was developed via a non-structured consensus process by Swiss dermatologists in hospitals and private practices to illustrate the current treatment options to general practitioners and dermatologists in Switzerland. Defining treatment goals together with the patient is crucial and increases treatment adherence. Patients' personal preferences and pre-existing experiences should be considered and their satisfaction with treatment and outcome regularly assessed. During the induction phase of "classical" mild-to-moderate psoriasis, the fixed combination of topical calcipotriol (Cal) 50 μg/g and betamethasone dipropionate (BD) 0.5 mg/g once daily is frequently used for 4-8 weeks. During the maintenance phase, a twice weekly (proactive) management has proved to reduce the risk of relapse. Of the fixed combinations, Cal/BD aerosol foam is the most effective formulation. However, the individual choice of formulation should be based on a patient's preference and the location of the psoriatic plaques. Tailored recommendations are given for the topical management of specific areas (scalp, facial, intertriginous/genital, or palmoplantar lesions), certain symptoms (hyperkeratotic or hyperinflammatory forms) as well as during pregnancy or a period of breastfeeding. As concomitant basic therapy, several emollients are recommended. If topical treatment alone does not appear to be sufficient, the regimen should be escalated according to the Swiss S1-guideline for the systemic treatment of psoriasis.

Salivary gland macrophages and tissue-resident CD8+ T cells cooperate for homeostatic organ surveillance

It is well established that tissue macrophages and tissue-resident memory CD8⁺ T cells (T_RM) play important roles for pathogen sensing and rapid protection of barrier tissues. In contrast, the mechanisms by which these two cell types cooperate for homeostatic organ surveillance after clearance of infections is poorly understood. Here, we used intravital imaging to show that T_RM dynamically followed tissue macrophage topology in noninflamed murine submandibular salivary glands (SMGs). Depletion of tissue macrophages interfered with SMG T_RM motility and caused a reduction of interepithelial T cell crossing. In the absence of macrophages, SMG T_RM failed to cluster in response to local inflammatory chemokines. A detailed analysis of the SMG microarchitecture uncovered discontinuous attachment of tissue macrophages to neighboring epithelial cells, with occasional macrophage protrusions bridging adjacent acini and ducts. When dissecting the molecular mechanisms that drive homeostatic SMG T_RM motility, we found that these cells exhibit a wide range of migration modes: In addition to chemokine- and adhesion receptor-driven motility, resting SMG T_RM displayed a remarkable capacity for autonomous motility in the absence of chemoattractants and adhesive ligands. Autonomous SMG T_RM motility was mediated by friction and insertion of protrusions into gaps offered by the surrounding microenvironment. In sum, SMG T_RM display a unique continuum of migration modes, which are supported in vivo by tissue macrophages to allow homeostatic patrolling of the complex SMG architecture.

COVID-19 and immunological regulations - from basic and translational aspects to clinical implications

The COVID‐19 pandemic caused by SARS‐CoV‐2 has far‐reaching direct and indirect medical consequences. These include both the course and treatment of diseases. It is becoming increasingly clear that infections with SARS‐CoV‐2 can cause considerable immunological alterations, which particularly also affect pathogenetically and/or therapeutically relevant factors.

Against this background we summarize here the current state of knowledge on the interaction of SARS‐CoV‐2/COVID‐19 with mediators of the acute phase of inflammation (TNF, IL‐1, IL‐6), type 1 and type 17 immune responses (IL‐12, IL‐23, IL‐17, IL‐36), type 2 immune reactions (IL‐4, IL‐13, IL‐5, IL‐31, IgE), B‐cell immunity, checkpoint regulators (PD‐1, PD‐L1, CTLA4), and orally druggable signaling pathways (JAK, PDE4, calcineurin). In addition, we discuss in this context non‐specific immune modulation by glucocorticosteroids, methotrexate, antimalarial drugs, azathioprine, dapsone, mycophenolate mofetil and fumaric acid esters, as well as neutrophil granulocyte‐mediated innate immune mechanisms.

From these recent findings we derive possible implications for the therapeutic modulation of said immunological mechanisms in connection with SARS‐CoV‐2/COVID‐19. Although, of course, the greatest care should be taken with patients with immunologically mediated diseases or immunomodulating therapies, it appears that many treatments can also be carried out during the COVID‐19 pandemic; some even appear to alleviate COVID‐19.

COVID‐19 und Immunregulation – von grundlegenden und translationalen Aspekten zu klinischen Implikationen

Die durch SARS‐CoV‐2 verursachte Pandemie COVID‐19 hat weitreichende direkte und indirekte medizinische Folgen. Dazu gehören sowohl der Verlauf als auch die Behandlung vieler Krankheiten. Es wird immer deutlicher, dass Infektionen mit SARS‐CoV‐2 erhebliche immunologische Veränderungen verursachen können, die insbesondere auch pathogenetisch und/oder therapeutisch relevante Faktoren betreffen.

Vor diesem Hintergrund fassen wir hier den aktuellen Wissensstand zur Interaktion von SARS‐CoV‐2/COVID‐19 mit Mediatoren der akuten Phase der Entzündung (TNF, IL‐1, IL‐6), der Typ‐1‐ und Typ‐17‐Immunantwort (IL‐12, IL‐23, IL‐17, IL‐36), Typ‐2‐Immunreaktionen (IL‐4, IL‐13, IL‐5, IL‐31, IgE), B‐Zell‐Immunität, Checkpoint‐Regulatoren (PD‐1, PD‐L1, CTLA4) und Signalwegen, die durch oral applizierte Medikamente moduliert werden (JAK, PDE4, Calcineurin), zusammen. Darüber hinaus diskutieren wir in diesem Zusammenhang die unspezifische Immunmodulation durch Glukokortikosteroide, Methotrexat, Malariamittel, Azathioprin, Dapson, Mycophenolsäure‐Derivate und Fumarsäureester sowie angeborene Immunmechanismen neutrophiler Granulozyten.

Aus diesen neueren Erkenntnissen leiten wir mögliche Implikationen für die therapeutische Modulation der genannten immunologischen Mechanismen im Zusammenhang mit SARS‐CoV‐2/COVID‐19 ab. Obwohl natürlich bei Patienten mit immunologisch vermittelten Krankheiten oder immunmodulierenden Therapien größte Vorsicht geboten ist, scheint es, dass viele Behandlungen auch während der COVID‐19‐Pandemie durchgeführt werden können; einige scheinen COVID‐19 sogar zu lindern.

Detection of autoantibodies against alpha-2-macroglobulin-like 1 in paraneoplastic pemphigus sera utilizing novel green fluorescent protein-based immunoassays

BACKGROUND

Paraneoplastic pemphigus (PNP) is a devastating autoimmune multiorgan syndrome associated with autoantibodies against several autoantigens, including the alpha-2-macroglobulin-like-1 (A2ML1). A2ML1 is recognized by up to 70 % of PNP sera. The currently recommended techniques for serological diagnosis of PNP are inadequate to detect anti-A2ML1 antibodies.

OBJECTIVES

To develop novel assays which allow to easily and reliably detect anti-A2ML1 autoantibodies in PNP sera.

METHODS

We produced full-length A2ML1 in fusion with enhanced green fluorescent protein (EGFP-A2ML1) in transfected human embryonic kidney 293 T cells. The recombinant protein was used as fluorescent ligand for immunoprecipitation studies. We further developed an enzyme-linked immunosorbent assay (ELISA) by immobilizing EGFP-A2ML1 on 96-well plates.

RESULTS

A2ML1-positive PNP sera were able to immunoprecipitate EGFP-A2ML1. Direct measurement of fluorescence in immunoprecipitates correlates with the relative levels of anti-A2ML1 antibodies in the PNP sera. By the novel ELISA, based on the determined best cut-off value, 61 % of the tested 36 PNP sera were A2ML1 positive with a specificity of 88.9 % and a sensitivity of 95 %. The 20 tested normal sera (NHS) were negative, while 2 (10 %) of 20 pemphigus vulgaris and 3 (15 %) of 20 bullous pemphigoid sera showed borderline values.

CONCLUSIONS

Our novel immunoassays enable rapid stratification of PNP patients. The novel green fluorescent protein-based ELISA utilizing an active eukaryotic A2ML1 is highly sensitive and reliable and, hence, is useful for a better understanding of the immunological background of PNP. This approach may be easily applied for the rapid detection of antibodies to various other antigens.

Human "TH9" cells are a subpopulation of PPAR-γ+ TH2 cells

Although T_H1, T_H2, and T_H17 cells are well-defined T_H cell lineages in humans, it remains debated whether IL-9-producing T_H cells represent a bona fide "T_H9" lineage. Our understanding of the cellular characteristics and functions of IL-9-producing T_H cells in humans is still nascent. Here, we report that human IL-9-producing T_H cells express the chemokine receptors CCR4 and CCR8, produce high levels of IL-5 and IL-13, and express T_H2 lineage-associated transcription factors. In these cells, IL-9 production is activation dependent, transient, and accompanied by down-regulation of T_H2 cytokines, leading to an apparent "T_H9" phenotype. IL-9⁺ T_H2 cells can be distinguished from "conventional" T_H2 cells based on their expression of the transcription factor PPAR-γ. Accordingly, PPAR-γ is induced in naïve T_H cells by priming with IL-4 and TGF-β ("T_H9" priming) and is required for IL-9 production. In line with their identity as early activated T_H2 cells, IL-9⁺ T_H2 cells are found in acute allergic skin inflammation in humans. We propose that IL-9-producing T_H cells are a phenotypically and functionally distinct subpopulation of T_H2 cells that depend on PPAR-γ for full effector functions.

Hidradenitis Suppurativa: Current Understanding of Pathogenic Mechanisms and Suggestion for Treatment Algorithm

Hidradenitis suppurativa is one of the most distressing dermatological conditions and has a significant negative impact on patients' quality of life. However, the exact pathogenic mechanisms remain incompletely understood and-therefore-efficient therapies are still lacking. The current manuscript focuses on new findings on its pathogenic mechanisms and aims to provide practical therapy recommendations.

Regulatory T Cells Restrain Pathogenic T Helper Cells during Skin Inflammation

Psoriasis is a chronic relapsing, remitting interleukin (IL)-23/IL-17-driven skin disease mediated by the interplay of T cells and polymorphonuclear granulocytes. Although preclinical studies have provided insights into the mechanisms of disease initiation, the underpinnings of natural disease remission remain largely unknown. Here, we addressed the contribution of regulatory Foxp3⁺ T cells (Treg cells) in psoriasiform skin inflammation and remission using the Aldara-skin inflammation model in combination with the inducible depletion of Foxp3⁺ Treg cells. Loss of Treg cells exacerbated skin inflammation, but this did not involve increased γδ T cell expansion or the local production of the psoriasis-associated cytokines IL-17A, IL-17F, and IL-22, which are the main driving forces of disease development. Instead, Treg cells suppressed the infiltration of granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing CD4⁺ T cells into the lesioned skin, and neutralizing GM-CSF in Treg cell-deficient mice reversed hyper-inflammation, resulting in disease regression. Therefore, we identified a non-redundant role of Treg cells restraining skin inflammation and mediating skin homeostasis.

Targeting T Cell Metabolism in Inflammatory Skin Disease

A properly functioning T cell compartment is crucial to protect the host from infections, tumors, and environmental substances. In recent years, it has become increasingly clear that the processes underlying proper T cell activation, proliferation, and differentiation require well-tuned and dynamic changes in T cell metabolism. Thus, proper metabolic reprogramming in T cells is crucial to ensure proper immunity in the context of infection and anti-tumor immunity. Conversely, aberrant regulation of T cell metabolism can impair T cell function and thereby contribute to T cell-mediated disease. In this review, the relevance of recent insights into T cell metabolism for prototypical T cell-mediated skin diseases will be discussed and their therapeutic potential will be outlined. First, the major modules of T cell metabolism are summarized. Then, the importance of T cell metabolism for T cell-mediated skin diseases such as psoriasis and allergic contact dermatitis is discussed, based on the current state of our understanding thereof. Finally, novel therapeutic opportunities for inflammatory skin disease that might emerge from investigations in T cell metabolism are outlined.

Diagnosis of mycobacterial skin infections

The diagnosis of cutaneous mycobacterial infections may be challenging. Owing to the broad spectrum of their clinical presentations, mycobacterioses have to be considered as differential diagnoses to many inflammatory dermatoses. Diagnostic measures comprise histology including special staining, cultures and molecular microbiological examinations as well as the detection of cellular immune reactions of the patient by means of interferon-γ release assays and skin testing. Clinicians should know the appropriate use and combination of procedures to diagnose mycobacterioses quickly and correctly and to avoid costs and delays caused by unnecessary examinations. This mini review summarizes advantages, limitations, and pitfalls of diagnostic methods for mycobacterial skin infections.

Effects of Omalizumab on FcεRI and IgE Expression in Lesional Skin of Bullous Pemphigoid

Recent studies suggest an important role of immunoglobulin E (IgE) as an alternative pathogenic pathway in the development of bullous pemphigoid (BP), as the most frequent subepidermal blistering disease of the skin Use of IgE targeted therapies, such as omalizumab, has been shown promising in recent studies. The aim of this study was to assess the effect of omalizumab on FcεRI and IgE expression on circulating basophils and on lesional intradermal cells in BP to generate insight into the immunological effects of omalizumab in BP. We report two cases of BP patients treated with omalizumab. Efficacy of treatment was assessed clinically 4 months after initiation of the therapy. Lesional and non-lesional skin biopsies where taken before and 4 weeks after initiation of omalizumab therapy. In addition, FcεRI expression on circulating cells and IgE levels in serum and in the skin samples, as well as anti-BP180 and anti-BP230 in serum and eosinophils and basophils counts in blood were assessed before and during treatment. Both patients showed a marked improvement after 4 months, with no adverse effects. Down-regulation of FcεRI, IgE in lesional skin and on circulating basophils were observed in parallel with clinical improvement. The current case study supports the role of omalizumab in the treatment of a subset of BP patients. Our observations suggest that omalizumab represents a valuable therapeutic option in the management of BP patients. Its efficacy might be related to reduction in FcεRI+ and IgE+ basophils and intradermal cells.

Association of Hidradenitis Suppurativa With T Helper 1/T Helper 17 Phenotypes: A Semantic Map Analysis

Importance

In spite of progress in understanding the mechanisms underlying hidradenitis suppurativa (HS) as an inflammatory skin disease, there is still a demand for an overview on immunopathogenesis of HS.

Objective

To demonstrate the importance of the type 1/type 17 immune response in lesional HS skin by drawing a semantic connectivity map.

Design, Setting, and Participants

Single-center case series of 24 patients with HS. Association of HS with T helper 1/T helper 17 (TH1/TH17) phenotype was assessed using semantic map analysis.

Main Outcomes and Measures

Association of HS with TH1/TH17 phenotype.

Results

The analysis was performed on 24 lesional HS biopsy samples from untreated patients with HS (16 [67%] female; median age, 36.5 years [range, 21-51 years]) with a mean (SD) Hurley stage of 2.29 (0.62) and 9 punch biopsy samples from healthy controls (6 [67%] female; median age, 43 years [range, 23-66 years]). The map shows a clustering of all TH1/TH17-associated cytokines (interleukin 17 [IL-17], interferon γ, IL-12, IL-23, IL-32, IL-1β, tumor necrosis factor) around overall lesional inflammation. Tumor necrosis factor, IL-12, and IL-17 are even directly connected via interferon γ. In contrast, IL-13, a TH2-associated cytokine, was inversely correlated with the presence of TH1/TH17-associated cytokines, further highlighting the importance of the TH1/TH17 cytokines in HS pathogenesis.

Conclusions and Relevance

These findings suggest that HS may be a TH1/TH17-driven inflammatory skin disease.