Eosinophil Cationic Protein (ECP), a predictive marker of bullous pemphigoid severity and outcome

Immune cells in skin inflammation, wound healing, and skin cancer

Given the self-evident importance of cutaneous immunity in the maintenance of body-surface homeostasis, disturbance of the steady-state skin is inextricably intertwined with dysfunction in cutaneous immunity. It is often overlooked by people that skin, well-known as a solid physical barrier, is also a strong immunological barrier, considering the abundant presence of immune cells including lymphocytes, granulocytes, dendritic cells, and macrophages. What's more, humoral immune components including cytokines, immunoglobulins, and antimicrobial peptides are also rich in the skin. This review centers on skin inflammation (acute and chronic, infection and aseptic inflammation), wound healing, and skin cancer to elucidate the elaborate network of immune cells in skin diseases.

Nucleic acid degradation as barrier to gene delivery: a guide to understand and overcome nuclease activity

Gene therapy is on its way to revolutionize the treatment of both inherited and acquired diseases, by transferring nucleic acids to correct a disease-causing gene in the target cells of patients. In the fight against infectious diseases, mRNA-based therapeutics have proven to be a viable strategy in the recent Covid-19 pandemic. Although a growing number of gene therapies have been approved, the success rate is limited when compared to the large number of preclinical and clinical trials that have been/are being performed. In this review, we highlight some of the hurdles which gene therapies encounter after administration into the human body, with a focus on nucleic acid degradation by nucleases that are extremely abundant in mammalian organs, biological fluids as well as in subcellular compartments. We overview the available strategies to reduce the biodegradation of gene therapeutics after administration, including chemical modifications of the nucleic acids, encapsulation into vectors and co-administration with nuclease inhibitors and discuss which strategies are applied for clinically approved nucleic acid therapeutics. In the final part, we discuss the currently available methods and techniques to qualify and quantify the integrity of nucleic acids, with their own strengths and limitations.

Risk factors predisposing relapse of bullous pemphigoid at initial diagnosis: A retrospective cohort study of 205 patients

BACKGROUND

Previous studies have revealed the factors associated with the relapse of bullous pemphigoid (BP). This study aims to assess the characteristics of BP patients at the time of initial diagnosis and a potential association with subsequent relapse occurrences.

METHODS

A retrospective cohort study was conducted on 205 BP patients from January 2009 to May 2022 at the Peking Union Medical College Hospital in Beijing, China. The median follow-up duration was 2.7 years. We conducted univariate and multivariate analyses on various clinical indicators (e.g., lesional involvements and medical history) and laboratory test results.

RESULTS

Among the 205 patients, 118 (57.6 %) relapsed during the follow-up period. Univariate analysis revealed several factors associated with relapse, which were greater age [Hazard Ratio (HR)1.018, 95 % confidence interval (CI) 1.004-1.032] (p = 0.010), a past medical history of thyroid diseases [HR 3.674, 95 % CI 1.472-9.167] (p = 0.005), hematological disease complications [HR 4.123, 95 % CI 1.301-13.061] (p = 0.016), negative C3 deposition in direct immunofluorescence [HR 0.574, 95 % CI 0.374-0.883] (p = 0.011) and prealbumin level less than 200 mg/L[HR 0.580, 95 % CI 0.351-0.957] (p = 0.033). Multivariate analysis demonstrated that patients with negative C3 deposition in direct immunofluorescence [HR 0.524, 95 % CI 0.296-0.927] (p = 0.026) and prealbumin levels below 200 mg/L [HR 0.541, 95 % CI 0.301-0.974] (p = 0.041) were associated with further relapses of BP.

CONCLUSIONS

Negative C3 deposition in direct immunofluorescence and a prealbumin level below 200 mg/L at initial diagnosis served as predictive markers for future relapses of BP. Systemic evaluation of BP patients at initial diagnosis could be essential in helping prevent recurrences and achieve more effective disease management.

Advancing Treatment in Bullous Pemphigoid: A Comprehensive Review of Novel Therapeutic Targets and Approaches

Bullous pemphigoid is one of the most common autoimmune bullous diseases occurring primarily in the elderly. Pathogenic autoantibodies against BP180 and BP230 at the dermal-epidermal junction cause subepidermal blisters, erosions, and intense pruritus, all of which adversely affect the patients' quality of life and may increase their morbidity and mortality. Current systemic treatment options for bullous pemphigoid are limited to corticosteroids and immunosuppressants, which can have substantial side effects on these vulnerable patients that even exceed their therapeutic benefits. Therefore, more precisely, targeting therapies to the pathogenic cells and molecules in bullous pemphigoid is an urgent issue. In this review, we describe the pathophysiology of bullous pemphigoid, focusing on autoantibodies, complements, eosinophils, neutrophils, proteases, and the T helper 2 and 17 axes since they are crucial in promoting proinflammatory environments. We also highlight the emerging therapeutic targets for bullous pemphigoid and their latest discoveries in clinical trials or experimental studies. Further well-designed studies are required to establish the efficacy and safety of these prospective therapeutic options.

Eosinophil-derived galectin-10 upregulates matrix metalloproteinase expression in bullous pemphigoid blisters

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune bullous disease in which abundant eosinophils accumulate in the blisters. Galectin-10 abounds in the cytoplasm of eosinophils and is released as a result of eosinophil extracellular trap cell death (EETosis).

OBJECTIVE

To identify EETosis and the pathological roles of galectin-10 in BP.

METHODS

EETosis and galectin-10 in BP blisters were confirmed by immunofluorescence and transmission electron microscopy. The concentrations of galectin-10 in serum and blister fluid from BP patients were studied by ELISA. The matrix metalloproteinase (MMP) expression in BP blisters was immunohistochemically compared to that in healthy controls. As an in vitro assay, normal human epidermal keratinocytes (NHEKs) and normal human dermal fibroblasts (NHDFs) were stimulated with galectin-10, followed by MMP expression measurement by real-time PCR and ELISA. The signaling pathways activated by galectin-10 were studied using Western blotting and confirmed by inhibition assays.

RESULTS

Galectin-10-containing eosinophil infiltration and the extracellular deposition of major basic protein were observed in BP blisters. The ultrastructural characteristics of tissue eosinophils indicated piecemeal degranulation and EETosis. In the BP patients, the concentration of galectin-10 was higher in the blister fluid than in the serum. Several types of MMPs were upregulated in BP blisters. Galectin-10 upregulated the production of MMPs through the pathways of p38 MAPK, ERK and JNK in NHEKs and NHDFs.

CONCLUSION

In the BP blisters, the eosinophils underwent EETosis and released galectin-10. Galectin-10 might contribute to BP blister formation through the production of MMPs by keratinocytes and fibroblasts.

Case Report: A Presentation of Early-Onset Immune-Mediated Bullous Pemphigoid in a Patient with Urothelial Cancer

Cutaneous immune-related adverse events (cirAEs) are the most common side effects of immune checkpoint inhibitor (ICI) therapy (30-50% for all grades). The vast majority of them are low or mild and can be treated without ICI interruption. Autoimmune blistering disorders, such as immune-mediated bullous pemphigoid (IBP), are rare (<1%) but potentially serious conditions that must be early detected. The onset generally occurs within the first months of the treatment, and it appears to be more common with antiprogrammed death-1 or antiprogrammed ligand 1 (anti-PD1/PDL1) than with anticytotoxic T-lymphocyte-associated protein 4 (anti-CTLA4). We present a case of a three-day severe IBP onset after receiving the first cycle of atezolizumab. This exceptional early presentation could suggest the presence of some predisposing condition and demonstrates the need to better understand predictive toxicity-related biomarkers in candidate patients for immunotherapy.

Targeting type 2 inflammation in bullous pemphigoid: current and emerging therapeutic approaches

Bullous pemphigoid (BP) is one of the most common autoimmune bullous diseases and mainly affects an elderly population with multi-morbidity. Due to the frailty of many BP patients, existing treatment options are limited. The blisters associated with BP result from IgG and IgE autoantibodies binding to the central components of hemidesmosome, BP180, and BP230, stimulating a destructive inflammatory process. The known characteristic features of BP, such as intense pruritus, urticarial prodrome, peripheral eosinophilia, elevated IgE, as well as recent expanding evidence from in vitro and in vivo studies implicate type 2 inflammation as an important driver of BP pathogenesis. Type 2 inflammation is an inflammatory pathway involving a subset of CD4+ T cells that secrete IL-4, IL-5, and IL-13, IgE-secreting B cells, and granulocytes, such as eosinophils, mast cells, and basophils. It is believed that effectors in type 2 inflammation may serve as novel and effective treatment targets for BP. This review focuses on recent understandings of BP pathogenesis with a particular emphasis on the role of type 2 inflammation. We summarize current clinical evidence of using rituximab (B-cell depletion), omalizumab (anti-IgE antibody), and dupilumab (anti-IL-4/13 antibody) in the treatment of BP. The latest advances in emerging targeted therapeutic approaches for BP treatment are also discussed.

Adaptive and innate immune pathogenesis of bullous pemphigoid: A review

Bullous pemphigoid (BP) is an autoimmune blistering disease that primarily affects elderly individuals. The presentation of BP is heterogeneous, typically manifesting as microscopic subepidermal separation with a mixed inflammatory infiltrate. The mechanism of pemphigoid development is unclear. B cells play a major role in pathogenic autoantibody production, and T cells, type II inflammatory cytokines, eosinophils, mast cells, neutrophils, and keratinocytes are also implicated in the pathogenesis of BP. Here, we review the roles of and crosstalk between innate and adaptive immune cells in BP.

Skin Eosinophil Counts in Bullous Pemphigoid as a Prognostic Factor for Disease Severity and Treatment Response

Dermal infiltration of eosinophils and eosinophilic spongiosis are prominent features of bullous pemphigoid lesions. Although several observations support the pathogenic role of eosinophils in bullous pemphigoid, few studies have examined the impact of skin eosinophil counts on disease severity and treatment response. This retrospective study assessed the association between eosinophil counts in skin biopsy samples of 137 patients with bullous pemphigoid and their demographic characteristics, comorbidities, disease severity, and treatment response. There was no relationship between eosinophil count and age, sex, or disease severity at disease onset. There was a positive relationship between eosinophil counts and neurological comorbidity and a negative relationship between eosinophil counts and treatment response. At all follow-up points patients with no tissue eosinophils had a better response to treatment than patients with any tissue eosinophil count. In conclusion, skin eosinophil counts in patients with bullous pemphigoid are not correlated with disease severity at onset, but can serve as a negative prognostic marker for treatment response.

Cross-sectional Study of Workers Employed at a Copper Smelter-Effects of Long-term Exposures to Copper on Lung Function and Chronic Inflammation

OBJECTIVE

The aim of the study was to assess the effect of exposure to copper-containing dust on lung function and inflammatory endpoints among workers of a German copper plant, effects rarely studied before.

METHODS

One hundred four copper-exposed smelter workers and 70 referent workers from the precious metal and lead facilities were included, with different metal exposures in both groups due to the different process materials. Body plethysmography, exhaled nitric oxide (FeNO) measurements, and blood sampling were conducted in all workers. Smoking status and the use of respiratory protective equipment were considered. In a subgroup of 40 nonsmoking volunteers (28 copper-exposed and 12 referents), sputum biomarkers were assessed.

RESULTS

Median lung function values of both copper-exposed and the referent groups were within reference ranges of "healthy" individuals, and statistical differences between the groups were mostly not evident. Similarly, differences in blood and sputum biomarkers were too small to be biologically relevant.

CONCLUSION

The results suggest the absence of the detectable effects of copper-containing dust exposure on lung function or chronic inflammation within the investigated cohort.

Insights Into the Pathogenesis of Bullous Pemphigoid: The Role of Complement-Independent Mechanisms

Bullous pemphigoid is an autoimmune blistering disease caused by autoantibodies targeting BP180 and BP230. While deposits of IgG and/or complement along the epidermal basement membrane are typically seen suggesting complement -mediated pathogenesis, several recent lines of evidence point towards complement-independent pathways contributing to tissue damage and subepidermal blister formation. Notable pathways include macropinocytosis of IgG-BP180 complexes resulting in depletion of cellular BP180, direct induction of pro-inflammatory cytokines from keratinocytes, as well as IgE autoantibody- and eosinophil-mediated effects. We review these mechanisms which open new perspectives on novel targeted treatment modalities.

A Review of the Immunologic Pathways Involved in Bullous Pemphigoid and Novel Therapeutic Targets

Bullous pemphigoid (BP) is a rare, chronic antibody-mediated autoimmune blistering disease primarily affecting the elderly, with an age of onset over 60. Current treatment options are limited and involve the use of corticosteroids and immunosuppressants, but their long-term use is associated with significant morbidity and mortality. In Japan, human intravenous immunoglobin is approved for the treatment of corticosteroid-refractory BP. However, no treatment option is approved by the Food and Drug Administration for the management of BP. Therefore, developing effective therapies free of debilitating side effects is imperative. In this review, we summarize the main immunologic pathways involved in the pathogenesis of BP, with an emphasis on the role of eosinophils, immunoglobulins, cytokines such as the interleukin (IL)-4 and IL-5, and complements. We further discuss the latest advances with novel therapeutic targets tested for the management of BP. Ongoing efforts are needed to run well-designed controlled trials and test the efficacy and safety of investigational drugs while providing much-needed access to these medications for refractory patients who will not otherwise be able to afford them as off-label prescriptions.

Emerging Biomarkers and Therapeutic Strategies for Refractory Bullous Pemphigoid

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disorder in the elderly. Systemic and topical use of glucocorticoids and immunosuppressants has been shown to be effective in most patients. However, refractory BP patients are challenged to clinicians with severe clinical symptoms, resistance to treatment, and high relapse rate. How to predict and assess the refractory and severity of bullous pemphigoid is the key issue in clinical practice, and the urgent need for precision medicine in refractory patients is driving the search for biomarkers and biologics. Recently, some biomarkers, such as the level of specific autoantibodies and released cytokines, have been proposed as the potential parameters to reflect the disease severity and predict the treatment response and relapse of refractory BP. Moreover, new biologics targeting pathogenic antibodies, complement, Th2 axis, eosinophils, and Th17 axis have shown potent efficacy on refractory BP. Here, we review the literature and give an overview of emerging biomarkers and therapeutic strategies for refractory bullous pemphigoid to improve the prognosis of the patient.

Plasma levels of D-dimer and fibrin degradation products correlate with bullous pemphigoid severity: a cross-sectional study

Bullous pemphigoid (BP), the most frequent blistering dermatosis in the elderly, is associated with increased mortality. The severity of BP can be assessed by detecting the anti-BP180 immunoglobulin G (IgG) concentration, but the lab test is not available in many community clinics. BP patients are usually in a hypercoagulable state with increased levels of D-dimer and fibrin degradation products (FDPs). We aimed to evaluate the use of D-dimer and FDPs in assessing BP severity. We compared the levels of plasma D-dimer, plasma FDPs, eosinophil counts, eosinophil cationic protein, and serum anti-BP180 IgG concentration between 48 typical BP patients and 33 Herpes zoster (HZ) patients (control group). Correlational analyses were conducted to determine the relationships between the lab values and common BP severity markers. The plasma D-dimer and FDP levels were higher in BP patients than in HZ controls (D-dimer: 3297 ± 2517 µg/L vs. 569.70 ± 412.40 µg/L; FDP: 9.74 ± 5.88 mg/L vs. 2.02 ± 1.69 mg/L, respectively, P < 0.0001). Significant positive correlations were found between D-dimer/FDP levels and BP severity markers (i.e. anti-BP180 IgG concentration [D-dimer: r = 0.3928, P = 0.0058; FDP: r = 0.4379, P = 0.0019] and eosinophil counts [D-dimer: r = 0.3625, P = 0.0013; FDP: r = 0.2880, P = 0.0472]) in BP patients. We also found an association between FDP and urticaria/erythema lesions (r = 0.3016, P = 0.0372), but no other BPDAI components. In 19 BP patients with complete remission after systemic glucocorticoid treatment, D-dimer and FDP levels decreased post-therapy (D-dimer: 5559 ± 7492 µg/L vs. 1738 ± 1478 µg/L; P < 0.0001; FDP: 11.20 ± 5.88 mg/L vs. 5.13 ± 3.44 mg/L; P = 0.0003), whereas they did not in BP patients with treatment resistant. Plasma D-dimer and FDP are convenient markers to evaluate BP severity assistant on BPDAI and eosinophil counts. FDP is also helpful for inflammatory lesions in BP patients.

Tissue eosinophil levels as a marker of disease severity in bullous pemphigoid

BACKGROUND

Eosinophils play an important role in bullous pemphigoid (BP) pathogenesis. Although tissue infiltration with eosinophils has been known for a long time, there is a lack of knowledge about the relationship between tissue eosinophil levels and disease severity and clinical characteristics of the patients.

METHODS

Fifty-nine patients diagnosed with BP between January 2008 and December 2018 were reviewed. Haematoxylin-Eosin (H&E)-stained preparations were re-evaluated in terms of tissue eosinophil levels. For disease severity, Bullous Pemphigoid Disease Area Index (BPDAI) was used. The relationship between tissue eosinophil levels and disease severity and clinical features were evaluated.

RESULTS

Erosion/blister and urticaria/erythema BPDAI scores were higher in the group with high tissue eosinophil level than the group with low tissue eosinophil level. Tissue and peripheral blood eosinophil count were correlated with total urticaria/erythema BPDAI scores. There was no correlation between blood and tissue eosinophil count. The mortality rate was 64.7% vs 44.0% in the high vs low tissue eosinophil groups. Tissue eosinophil levels were high in patients with BP accompanying neurological disease.

CONCLUSIONS

Tissue eosinophil count and peripheral blood eosinophil count were correlated with disease severity in BP. Tissue eosinophil levels were also high in patients with BP accompanying neurological disease.

Clinical characteristics and outcomes of bullous pemphigoid patients with versus without oral prednisolone treatment

Bullous pemphigoid (BP) varies in severity and stratified treatments are needed. However, there are no definitive standards for choosing appropriate treatments. To elucidate the factors involved in choosing treatments and the clinical outcomes of BP, we retrospectively reviewed the clinical records of 78 BP patients at a single center. Of the 78 patients, 49 (62.8%) were treated with oral prednisolone (PSL) and 29 (37.2%) were treated without PSL. The patients with older age, lower Bullous Pemphigoid Disease Area Index (BPDAI), and/or lower anti-BP180NC16a antibody titer at onset tended to be treated without oral PSL. Notably, only 9.1% patients without PSL experienced relapse, whereas 36.7% patients with oral PSL experienced relapse when the PSL was around 0.1 mg/kg. It suggests that the patients with mild disease severity could be well controlled without oral PSL. Receiver-operator curve analysis demonstrated that the cut-off value for the use of oral PSL was 31 for total BPDAI and was 7 for BPDAI skin urticaria/erythema, with a high (>0.9) area under the curve. Notably, none of the patients who were negative for the anti-BP180NC16a antibody at onset experienced relapse even though they were treated without PSL. In conclusion, in BP patients who were negative for anti-BP180NC16a antibody at onset, with a total BPDAI score of less than 31 or with an urticaria/erythema score of less than 7 can be treated without PSL. When the PSL is tapered to around 0.1 mg/kg, we should carefully monitor the patients to detect relapse.

Milestones in Personalized Medicine in Pemphigus and Pemphigoid

Pemphigus and pemphigoid diseases are autoimmune bullous diseases characterized and caused by autoantibodies targeting adhesion molecules in the skin and/or mucous membranes. Personalized medicine is a new medical model that separates patients into different groups and aims to tailor medical decisions, practices, and interventions based on the individual patient`s predicted response or risk factors. An important milestone in personalized medicine in pemphigus and pemphigoid was achieved by verifying the autoimmune pathogenesis underlying these diseases, as well as by identifying and cloning several pemphigus/pemphigoid autoantigens. The latter has become the basis of the current, molecular-based diagnosis that allows the differentiation of about a dozen pemphigus and pemphigoid entities. The importance of autoantigen-identification in pemphigus/pemphigoid is further highlighted by the emergence of autoantigen-specific B cell depleting strategies. To achieve this goal, the chimeric antigen receptor (CAR) T cell technology, which is used for the treatment of certain hematological malignancies, was adopted, by generating chimeric autoantigen receptor (CAAR) T cells. In addition to these more basic science-driven milestones in personalized medicine in pemphigus and pemphigoid, careful clinical observation and epidemiology are again contributing to personalized medicine. The identification of clearly distinct clinical phenotypes in pemphigoid like the non-inflammatory and gliptin-associated bullous pemphigoid embodies a prominent instance of the latter. We here review these exciting developments in basic, translational, clinical, and epidemiological research in pemphigus and pemphigoid. Overall, we hereby aim to attract more researchers and clinicians to this highly interesting and dynamic field of research.

Bullous Pemphigoid: Trigger and Predisposing Factors

Bullous pemphigoid (BP) is the most frequent autoimmune subepidermal blistering disease provoked by autoantibodies directed against two hemidesmosomal proteins: BP180 and BP230. Its pathogenesis depends on the interaction between predisposing factors, such as human leukocyte antigen (HLA) genes, comorbidities, aging, and trigger factors. Several trigger factors, such as drugs, thermal or electrical burns, surgical procedures, trauma, ultraviolet irradiation, radiotherapy, chemical preparations, transplants, and infections may induce or exacerbate BP disease. Identification of predisposing and trigger factors can increase the understanding of BP pathogenesis. Furthermore, an accurate anamnesis focused on the recognition of a possible trigger factor can improve prognosis by promptly removing it.

Silencing ICAM-1 reduces the adhesion of vascular endothelial cells in mice with immunologic contact urticaria

OBJECTIVE

Immunologic contact urticaria (ICU) is an immediate response of wheal caused by various contactants in vulnerable individuals, with undefined pathogenesis.

METHODS

In the present study, we aim to explore the effects of intercellular cell adhesion molecule-1 (ICAM-1) gene silencing by RNA inference (RNAi) on vascular endothelial cells (VECs) adhesion molecule expression and cell-cell adhesion in ICU mice. Sixty BALB/c mice were selected, among which 48 mice were used for establishment of ICU models. VECs from normal and ICU mice were grouped into different groups. Expressions of ICAM-1, eosinophilic cationic protein (ECP), total immunologlobulin E (tIgE), L-selectin (CD62L), integrin, alpha L (CD11a) in tissues and cells were evaluate by RT-qPCR and western blotting. Cell proliferation was evaluated by MTT assay and EdU staining and cell adhesive function by cell-cell adhesion assay.

RESULTS

Compared with normal mice, ICU mice had increased expressions of ICAM-1, ECP, tIgE, CD62L, and CD11a.ICAM-1 gene silencing decreased expressions of ECP, tIgE, CD62L, and CD11a, enhanced cell proliferation, and more activity in cell adhesion.

CONCLUSION

These findings indicate that RNAi-mediated gene silencing of ICAM-1 may decrease VECs adhesion expression and reduce cell-cell adhesion in mice with ICU.

Eosinophils in Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disorder with substantial morbidity and mortality. BP is regarded as a disorder driven by IgG due to BP180 and BP230 IgG autoantibodies, yet, new advances highlight the function of eosinophils and IgE autoantibodies in BP. Evidence supports that eosinophils are involved in BP pathogenesis, notably, these include the presence of IL-5, eotaxin, and eosinophil-colony stimulating factor in blister fluid, peripheral blood eosinophilia is present in nearly 50% of affected patients, eosinophils are found against the dermo-epidermal junction (DEJ) when BP serum is present, metalloprotease-9 is secreted by eosinophils at blister sites, blister fluid of BP patients contains eosinophil granule proteins which are located along the lamina lucida of the BMZ in patients with BP and correspond with disease clinically, eosinophil extracellular traps (EET) have been linked to DEJ splitting, IL-5 activated eosinophils cause DEJ separation when BP serum is present, and eosinophils are requisite to drive anti-BP180 IgE mediated blistering of the skin. Yet, the mechanism whereby eosinophils contribute to the pathogenesis of BP remains to be explored. In this review, we examine the role of eosinophils in BP while offering a basis to explain the pathomechanisms of eosinophils in BP.

Factors associated with the activity and severity of bullous pemphigoid: a review

Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease. It usually affects people older than 70 years of age. The two main autoantigens are BP180 and BP230, both of which are components of hemidesmosomes. Immunoglobulin (Ig)G and IgE autoantibodies to BP180 detected by the enzyme-linked immunoassay (ELISA) show close associations with the activity and severity of BP. In addition, inflammatory cells (eosinophils, neutrophils and mast cells) and cytokines (e.g. interleukins and CC chemokine ligands) play an important part in the pathogenesis, activity and severity of BP. We summarized the potential contribution of each factor postulated to be associated with the activity and severity of BP, and provide guidance for clinicians to pay timely and close attention to such parameters. This review may also promote the development of novel therapies for BP.Key MessagesBullous Pemphigoid Disease Area Index (BPDAI) is a scoring system which can reflect the extent of clinical involvement of BP patients.The titres of IgE autoantibodies and IgG autoantibodies against the NC16A domain of BP180 are closely correlated with the activity and severity of BP.Many inflammatory cells and molecules, such as eosinophils and interleukins, can also reflect the activity and severity of BP.

Bullous pemphigoid associated with the use of dipeptidil peptidase-4 inhibitors: analysis from studies based on pharmacovigilance databases

Background Bullous pemphigoid has been associated to dipeptidase-4 inhibitors. Objectives Addressing the potential Bullous pemphigoid-dipeptidase-4 inhibitors association based on pharmacovigilance data currently available in Spain in order to obtain a composite disproportionality estimator from all the data generated by the case-non case studies conducted to this date. Setting The Spanish Pharmacovigilance System for Human Use Drugs database. Method Case-non case study based on the Spanish Pharmacovigilance System for Human Use Drugs notifications submitted between 2007 and 2018 (n = 169,280), using the Medical Dictionary for Regulatory Activities term (Preferred Term) 'pemphigoid' for sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin (n = 1952). As negative control, we used acetaminophen, while furosemide was the positive control. A pooled reported odds ratio analysis in the French, Japanese, and Spanish national pharmacovigilance databases was performed. On The Spanish Pharmacovigilance System for Human Use Drugs, we conducted a bullous pemphigoid-metformin association analysis within the period 1982-2018. Main outcome measure Adverse reaction cases in pharmacovigilance databases and the disproportionality through the reporting odds ratio. Results Within The Spanish Pharmacovigilance System for Human Use Drugs, we found 45 cases of bullous pemphigoid in dipeptidase-4 inhibitors patients. Median age was 77 years (range 72-82). The median latency period was 7 months (range 0.23-86). The Bullous pemphigoid-dipeptidase-4 inhibitors association was established with a reporting odd ratio = 70.0 (95% confidence intervals 49.1-10.1). In the combined analysis of the three aforementioned pharmacovigilance databases, the pooled reporting odd ratio was 81.0 (95% confidence intervals 69.5-94.4). Conclusion The composite estimator for the three national pharmacovigilance databases yields clear evidence of a Bullous pemphigoid-dipeptidase-4 inhibitors association, which was statistically significant for both the pharmacological class as a whole and each of the dipeptidase-4 inhibitors agents under investigation. Metformin's role in the incidence of bullous pemphigoid appeared casual rather than causal. No differences between Caucasian and Asian populations were noted.

The Intersection of IgE Autoantibodies and Eosinophilia in the Pathogenesis of Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting cellular adhesion molecules. While IgE autoantibodies are occasionally reported in other autoimmune blistering diseases, BP is unique in that most BP patients develop an IgE autoantibody response. It is not known why BP patients develop self-reactive IgE and the precise role of IgE in BP pathogenesis is not fully understood. However, clinical evidence suggests an association between elevated IgE antibodies and eosinophilia in BP patients. Since eosinophils are multipotent effector cells, capable cytotoxicity and immune modulation, the putative interaction between IgE and eosinophils is a primary focus in current studies aimed at understanding the key components of disease pathogenesis. In this review, we provide an overview of BP pathogenesis, highlighting clinical and experimental evidence supporting central roles for IgE and eosinophils as independent mediators of disease and via their interaction. Additionally, therapeutics targeting IgE, the Th2 axis, or eosinophils are also discussed.

IL-23/IL-17 Axis Activates IL-1β-Associated Inflammasome in Macrophages and Generates an Auto-Inflammatory Response in a Subgroup of Patients With Bullous Pemphigoid

Bullous Pemphigoid (BP) is a skin autoimmune blistering disease characterized by immune-mediated degradation of the dermo-epidermal junction and release of a large number of inflammatory cytokines. Interleukin-1β (IL-1β) is a pleiotropic pro-inflammatory cytokine associated with inflammasome activation and known to be pivotal in several auto-immune and auto-inflammatory diseases. We sought to clarify the presence of inflammasome-dependent IL-1β and to investigate its role in BP. Skin biopsy specimens (n = 13), serum (n = 60), blister fluid (n = 26), and primary inflammatory cells from patients with BP were used to investigate inflammasome activation and function. We here highlighted a differential occurrence of a functional in situ inflammasome in patients with BP, biologically distinguished by IL-1β and NLRP3 expression. Clinically, elevated IL-1β levels were associated with the presence of erythema and urticarial plaques reflecting the inflammatory phase preceding blister formation. We further identified IL-17 and IL-23 as important molecules favoring IL-1β expression in monocyte-derived macrophages from BP patients. Finally, we demonstrated the ability of IL-1β to stimulate the release of the matrix metalloproteinase-9 in those macrophages, reinforcing the role of IL-1β in the auto-amplification loop of the inflammatory response associated to BP. However, whether this inflammasome is an epiphenomenon associated with BP disease or constitutes an amplification inflammatory step in certain patients still need to be determined. In the context of a precision medicine approach, our findings allowed us to delineate a subgroup of patients with BP that showed similarities with auto-inflammatory diseases. Subsequently, this opens up alternative therapeutic strategies targeting IL-1β pathway in the aim to control the early, pre-blistering inflammatory phase. Ultimately, this could also help in reducing the detrimental effects associated with high doses of corticosteroids treatment.

Serological Diagnosis of Autoimmune Bullous Skin Diseases

Autoimmune bullous dermatoses (AIBD) encompass a variety of organ-specific autoimmune diseases that manifest with cutaneous and/or mucosal blisters and erosions. They are characterized by autoantibodies targeting structural proteins of the skin, which are responsible for the intercellular contact between epidermal keratinocytes and for adhesion of the basal keratinocytes to the dermis. The autoantibodies disrupt the adhesive functions, leading to splitting and blister formation. In pemphigus diseases, blisters form intraepidermally, whereas in all other disease types they occur subepidermally. Early identification of autoimmune bullous dermatoses is crucial for both treatment and prognosis, particularly as regards tumor-associated disease entities. The diagnosis is based on clinical symptoms, histopathology, direct immunofluorescence to detect antibody/complement deposits, and the determination of circulating autoantibodies. The identification of various target antigens has paved the way for the recent development of numerous specific autoantibody tests. In particular, optimized designer antigens and multiplex test formats for indirect immunofluorescence and ELISA have enhanced and refined the laboratory analysis, enabling highly efficient serodiagnosis and follow-up. This review elaborates on the current standards in the serological diagnostics for autoimmune bullous dermatoses.

Targeted Therapies for Autoimmune Bullous Diseases: Current Status

Autoimmune bullous skin disorders are rare but meaningful chronic inflammatory diseases, many of which had a poor or devastating prognosis prior to the advent of immunosuppressive drugs such as systemic corticosteroids, which down-regulate the immune pathogenesis in these disorders. Glucocorticoids and adjuvant immunosuppressive drugs have been of major benefit for the fast control of most of these disorders, but their long-term use is limited by major side effects such as blood cytopenia, osteoporosis, diabetes mellitus, hypertension, and gastrointestinal ulcers. In recent years, major efforts were made to identify key elements in the pathogenesis of autoimmune bullous disorders, leading to the identification of their autoantigens, which are mainly located in desmosomes (pemphigus) and the basement membrane zone (pemphigoids). In the majority of cases, immunoglobulin G, and to a lesser extent, immunoglobulin A autoantibodies directed against distinct cutaneous adhesion molecules are directly responsible for the loss of cell-cell and cell-basement membrane adhesion, which is clinically related to the formation of blisters and/or erosions of the skin and mucous membranes. We describe and discuss novel therapeutic strategies that directly interfere with the production and regulation of pathogenic autoantibodies (rituximab), their catabolism (intravenous immunoglobulins), and their presence in the circulation and extravascular tissues such as the skin (immunoadsorption), leading to a significant amelioration of disease. Moreover, we show that these novel therapies have pleiotropic effects on various proinflammatory cells and cytokines. Recent studies in bullous pemphigoid suggest that targeting of immunoglobulin E autoantibodies (omalizumab) may be also beneficial. In summary, the introduction of targeted therapies in pemphigus and pemphigoid holds major promise because of the high efficacy and fewer side effects compared with conventional global immunosuppressive therapy.

Coagulation and Skin Autoimmunity

Several lines of evidence indicate that the immune system, inflammation, and coagulation are simultaneously activated in autoimmune and immune-mediated skin diseases. Pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor-alpha induce the expression of the main initiator of coagulation, i.e., tissue factor. The proteases of coagulation in turn act on protease-activated receptors inducing the expression of various pro-inflammatory cytokines triggering inflammation. The cross-talk among immune system, inflammation, and coagulation amplifies and maintains the activation of all three pathways. This review focuses on three skin disorders as chronic spontaneous urticaria (CSU), angioedema, and bullous pemphigoid (BP), in which the relationships among the three systems have been investigated or their clinical consequences are relevant. Markers of thrombin generation, fibrinolysis, and inflammation have been reported to be increased in the plasma during flares of CSU and angioedema, as well as in the active phase of BP, with the marker levels reverting to normal during remission. The coagulation activation seems to be important only at local level in CSU and angioedema while both at local and systemic levels in BP which is the only condition associated with an increased thrombotic risk. The prothrombotic state in autoimmune skin diseases raises the question of the indication of anticoagulant treatment, particularly in the presence of other cardiovascular risk factors.

NET Formation in Bullous Pemphigoid Patients With Relapse Is Modulated by IL-17 and IL-23 Interplay

Background: DNA extracellular traps (ETs), released by neutrophils (NETs), or eosinophils (EETs), play a pathogenic role in several autoimmune disorders. However, to date, NETs have never been investigated in bullous pemphigoid (BP) with respect to clinical and immunological activities, both at baseline and at time of relapse which have been characterized with specific IL-17 and IL-23 patterns. Objective: We sought to assess whether ETs were associated with BP as well as the relative contribution of IL-17 axis cytokines to NET induction. Methods: Skin biopsy specimens were obtained from 11 patients with BP. Immuno-detection of neutrophils and eosinophils combined to DNA staining allowed us to investigate the in-situ presence of NETs and EETs using confocal scanning microscopy. NETs release was evaluated ex vivo by stimulating polymorphonuclear cells from BP patients with BP biological fluids in presence of IL-17A and IL-23 or of glucocorticoids. Results: At baseline, ETs were observed in BP lesions at the site of dermal-epidermal cleavage. Despite an important infiltrate of eosinophils, ETs were essentially associated with neutrophils in situ and were not related to BP clinical activity at diagnosis. In situ observation of NETs was associated in 6 among 8 patients with serum capacity of NET induction. Notably both blister fluid and sera from BP patients at diagnosis and at time of relapse could induce NET formation ex vivo. In contrast, a longitudinal investigation showed a decrease of NET formation with time of treatment in patients undergoing remission. Mimicking relapse, complementation of sera from BP patients with ongoing remission with either IL-17A or IL-23 increased NET formation. Conversely, IL-17A inhibited NET formation induced by serum from BP patients with relapse supplemented or not with IL-23. Finally, glucocorticoids also inhibited NET formation ex vivo in BP. Conclusion: NET formation is an associated phenomenon with BP. Furthermore, we showed that IL-23 favored NET formation, whereas the effects of IL-17A are environment dependent. Indeed, IL-17A displayed a protective effect on NET formation when associated with IL-23, showing for the first-time differential effects of these two cytokines in BP.

Biomarkers related to bullous pemphigoid activity and outcome

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease of the skin. Investigation of the BP-associated pathophysiological processes during the last decades showed that the generation of autoantibodies directed against the hemidesmosome proteins BP180 and BP230, a hallmark of the BP-associated autoimmune response, leads to the recruitment of inflammatory immune cells at the dermal-epidermal junction, and subsequently to the release of a large amount of inflammatory molecules involved in blister formation. Analysis in transversal and longitudinal studies of autoantibodies and inflammatory molecules production both at the time of diagnosis and under treatment was mainly performed within the serum but also in the blister fluid. Some autoimmune or inflammatory molecules expression was related to the presence of clinical signs, while others were mere bystanders. In this review, we focused on the autoimmune and inflammatory molecules that have been identified as potential biomarkers of BP development and outcome.

Mechanisms of pathogenic effects of eosinophil cationic protein and eosinophil-derived neurotoxin on human keratinocytes

Cutaneous deposition of eosinophil degranulation proteins is a major feature of eosinophil-rich cutaneous diseases including bullous pemphigoid (BP). We sought to better understand the effect of two of these proteins - eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN), on human keratinocytes using the Het-1A cell line. To evaluate expression of key cytokines and chemokines observed in BP as well as metal metalloprotease 9 (MMP9), we performed qPCR and in-cell Western assays on cells treated with either ECP or EDN. We further evaluated the effect of ECP and EDN on keratinocyte survival, generation of reactive oxygen species (ROS) and apoptosis. Lastly, we assessed ECP and EDN's ability to induce keratinocyte detachment from provisional matrix. Treatment of keratinocytes with ECP and EDN resulted in significant increases in IL-5, eotaxin-1 and CCL5 (RANTES) expression at both mRNA and protein levels, but not IL-17 or IL-31. ECP and EDN also upregulate MMP9 production. Inhibiting MMP9, we confirmed that keratinocyte expression of IL-5, eotaxin-1 and RANTES was independent from MMP9. Both ECP and EDN were cytotoxic to keratinocytes, inducing ROS formation and apoptosis through a mitochondrion-dependent pathway as evidenced by results of terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) and cytochrome c release assays, respectively. ECP but not EDN led to significant keratinocyte detachment from provisional matrix. These findings demonstrate that the pathogenic effects of ECP and EDN in BP may result from their direct action on keratinocytes, and as such may became a target for future therapies in eosinophil-rich cutaneous diseases.

Circulating Eosinophil and Neutrophil Counts Correlate with Disease Severity in Bullous Pemphigoid

Background

Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease characterized by tissue-bound and circulating autoantibodies directed against BP180 and/or BP230 antigens. Various inflammatory cells are involved in the development of blister in BP.

Objective

The aim of this study was to evaluate the correlation between peripheral leukocyte counts and BP severity.

Methods

We retrospectively included 60 patients with BP, who had not been treated with systemic steroid at the time of blood sampling. The patients were classified into two groups, those with admission history (admission group) and those without admission history (non-admission group). Disease severity was evaluated using three parameters: admission history, initial steroid dosage, and modified version of a pemphigus scoring system. We evaluated the correlation between peripheral leukocyte counts and disease severity measured by the three parameters.

Results

The admission group showed a significant increase in disease severity measured by initial steroid dosage and severity score compared with the non-admission group. Additionally, the admission group had increased total leukocyte, eosinophil, and neutrophil counts. In the correlation study, the peripheral eosinophil and neutrophil counts showed positive correlation with BP severity evaluated by both initial steroid dosage and the pemphigus scoring system.

Conclusion

Peripheral eosinophil and neutrophil counts can be used as a marker in predicting disease severity in patients with BP.

Effects of RNA interference-mediated E-selectin gene silencing on cell adhesion molecule expression and cell-cell adhesion in vascular endothelial cells in mice with immunologic contact urticaria

Contact urticaria is recognized as the wheal and flare reaction at a site from direct contact with a chemical or protein agent. Ongoing studies have proposed that gene silencing may have a promising future in finding optimal treatment of a variety of disease; hence, the aim of the study was to investigate the effect of RNA interference-mediated E-selectin ( SELE) gene silencing on cell adhesion molecule expression and on cell-cell adhesion in vascular endothelial cells (VECs) in a mouse model of immunologic contact urticaria (ICU). Following the successful establishment of mouse models of ICU induced by antidinitrophenol immunoglobulin E (IgE) combining 2,4-dinitrofluorobenzene challenge, enzyme-linked immunosorbent assay and immunohistochemistry were used to measure the levels of IgE, interleukin 4 (IL-4), interferon-γ (IFN-γ), and histamine as well as the positive expression rate of SELE, respectively. The siRNA- SELE vector was constructed and transfection efficiency was estimated prior to performing quantitative reverse-transcription polymerase chain reaction and Western blot assay to determine the relative expression of SELE, eosinophil cationic protein (ECP), intercellular adhesion molecule 1 (ICAM-1), L-selectin (CD62L), and the alpha chain of leukocyte function-associated antigen-1 (CD11a). Adhesion assay was then performed to assess the cell adhesion ability in VECs. Elevated levels of IgE, IL-4, IFN-γ, and histamine and increased positive expression rate of SELE were indicative of successful establishment of mouse models of ICU. Furthermore, the relative expression levels of SELE, ECP, ICAM-1, CD62L, and CD11a were highest in the OE- SELE group. Besides, cell adhesion ability of VECs was notably promoted. Collectively, the current study define the potential role of SELE silencing as an inhibitor to ICU development by inhibiting cell adhesion ability of VECs.

The Role of Eosinophils in Bullous Pemphigoid: A Developing Model of Eosinophil Pathogenicity in Mucocutaneous Disease

Bullous pemphigoid (BP) is an autoimmune blistering disease which carries a significant mortality and morbidity. While historically BP has been characterized as an IgG driven disease mediated by anti-BP180 and BP230 IgG autoantibodies, developments in recent years have further elucidated the role of eosinophils and IgE autoantibodies. In fact, eosinophil infiltration and eosinophilic spongiosis are prominent features in BP. Several observations support a pathogenic role of eosinophils in BP: IL-5, eotaxin, and eosinophil-colony stimulating factor are present in blister fluid; eosinophils line the dermo-epidermal junction (DEJ) in the presence of BP serum, metalloprotease-9 is released by eosinophils at the site of blisters; eosinophil degranulation proteins are found on the affected basement membrane zone as well as in serum corresponding with clinical disease; eosinophil extracellular DNA traps directed against the basement membrane zone are present, IL-5 activated eosinophils cause separation of the DEJ in the presence of BP serum; and eosinophils are the necessary cell required to drive anti-BP180 IgE mediated skin blistering. Still, it is likely that eosinophils contribute to the pathogenesis of BP in numerous other ways that have yet to be explored based on the known biology of eosinophils. We herein will review the role of eosinophils in BP and provide a framework for understanding eosinophil pathogenic mechanisms in mucocutaneous disease.

Relapse of bullous pemphigoid: an update on this stubborn clinical problem

Bullous pemphigoid (BP) is a chronic autoimmune blistering disorder that has a predilection for the elderly. It is characterized by a poor prognosis due to its high mortality rate and the tendency to relapse. The relapse rate of BP ranges from 27.87% to 53% after disease remission, while the majority of relapses occur early (within 6 months) during remission. Clinical interventions aimed to prevent early relapses could reduce potential complications from first-line treatment and make follow-up care easier for clinicians in practice, thus improving the prognosis of BP and the quality of patients' lives. In this article, we attempt to review previous studies from the medical literature concerning relapse and risk factors related to relapse in BP patients. Treatments found to be able to reduce or increase relapse rate were also discussed. We propose that clinicians be aware of these risk factors and manage proper treatment accordingly. Key Messages   • The relapse rate of bullous pemphigoid ranges from 27.87% to 53% after disease remission, while the majority of relapses occur early (within 6 months) during remission.   • Ageing, disease severity, neurological disorder, serum ECP, BAFF, IL-17, IL-23, CXCL10 and anti-BP180 antibody levels have been shown to be related to relapse, while confirmation studies are needed before using them for guidance for relapse prevention.   • Longer usage of corticosteroid with a low dose, combination of immunosuppressants and intravenous immunoglobulin are helpful in lowering relapse rate.

Anti-Type VII Collagen Antibodies Are Identified in a Subpopulation of Bullous Pemphigoid Patients With Relapse

Bullous pemphigoid (BP) is an autoimmune bullous skin disease characterized by anti-BP180 and anti-BP230 autoantibodies (AAbs). Mucous membrane involvement is an uncommon clinical feature of BP which may evoke epidermolysis bullosa acquisita, another skin autoimmune disease characterized by anti-type VII collagen AAbs. We therefore evaluated the presence of anti-type VII collagen AAbs in the serum of BP patients with and without mucosal lesions at time of diagnosis and under therapy. Anti-BP180, anti-BP230, and anti-type VII collagen AAbs were measured by ELISA in the serum of unselected patients fulfilling clinical and histo/immunopathological BP criteria at baseline (n = 71) and at time of relapse (n = 24). At baseline, anti-type VII collagen AAbs were detected in 2 out of 24 patients with BP presenting with mucosal involvement, but not in patients without mucosal lesions (n = 47). At the time of relapse, 10 out of 24 BP patients either displayed a significant induction or increase of concentrations of anti-type VII collagen AAbs (P < 0.01), independently of mucosal involvement. Those 10 relapsing BP patients were also characterized by a sustained high concentration of anti-BP180 AAb, whereas the serum anti-BP230 AAb concentrations did not vary in BP patients with relapse according to the presence of anti-type VII collagen AAbs. Thus, our study showed that anti-type VII collagen along with anti-BP180 AAbs detection stratified BP patients at time of relapse, illustrating a still dysregulated immune response that could reflect a potential epitope spreading mechanism in those BP patients.

Mucosal Involvement in Bullous Pemphigoid Is Mostly Associated with Disease Severity and to Absence of Anti-BP230 Autoantibody

Bullous pemphigoid (BP) is the most common autoimmune bullous disease and typically affects the elderly. Binding of specific autoantibodies to BP180/230 hemidesmosomal components induces an inflammatory response leading to skin blister formation. Unusual manifestations of BP include additional mucous membrane involvement, without pathophysiological knowledge associated to the formation of these lesions. We here performed a prospective study on series of consecutive BP patients with (n = 77) and without (n = 18) mucosal involvements at baseline to further investigate why some BP patients display mucosal lesion and other not. Analysis of disease activity showed that BP patients with mucosal involvement displayed a higher total BP Disease Area Index (BPDAI) score (P = 0.008), but also higher skin and blister/erosion BPDAI scores (P = 0.02 and P = 0.001, respectively). By contrast, the erythema/urticaria BPDAI score was identical between the two groups of patients. The erythema/urticaria BPDAI score, but not the blister/erosion BPDAI score, was correlated with the serum concentration of anti-BP180 NC16A autoantibodies in patients with mucosal involvement. In multivariate analysis, the absence of anti-BP230 autoantibody was the only factor independently associated with mucosal involvement (OR 7.8; 95% CI, 3.1–19.6) (P < 0.0001). Analysis of the distribution of BP patients according to BPDAI scores revealed a shift toward higher blister/erosion BPDAI scores for BP patients with mucosal involvement. This study indicates that mucosal lesions are clinically mainly related to disease severity and immunologically to the absence of anti-BP230 antibodies.

Differential Expression of Six Rnase2 and Three Rnase3 Paralogs Identified in Blunt Snout Bream in Response to Aeromonas hydrophila Infection

Ribonucleases (Rnases)2 and Rnase3 belong to the ribonuclease A (RnaseA) superfamily. Apart from their role in molecular evolutionary and functional biological studies, these genes have also been studied in the context of defense against pathogen infection in mammals. However, expression patterns, structures and response to bacterial infection of the two genes in blunt snout bream (Megalobrama amblycephala) remain unknown. In this study, we identified multiple copies of Rnase2 (six) and Rnase3 (three) in the M. amblycephala genome. The nine genes all possess characteristics typical of the RnaseA superfamily. No expression was detected in the early developmental stages, while a weak expression was observed at 120 and 140 h post-fertilization (hpf) for Rnase2b, Rnase2c, Rnase2e and Rnase3a, suggesting that only three copies of Rnase2 and one of Rnase3 are expressed. Interestingly, only Rnase2e was up-regulated in the kidney of M. amblycephala after Aeromonas hydrophila infection, while Rnase3a was significantly up-regulated in liver, gut and blood after the infection. We conclude that the paralogs of Rnase3 are more susceptible to A. hydrophila infection than Rnase2. These results indicate that different Rnase2 and Rnase3 paralogs suggest a role in the innate immune response of M. amblycephala to bacterial infection.