The Pathogenesis of Chronic Spontaneous Urticaria: The Role of Infiltrating Cells

Unveiling chronic spontaneous urticaria pathophysiology through systems biology

BACKGROUND

Chronic spontaneous urticaria (CSU) is a rare, heterogeneous, severely debilitating, and often poorly controlled skin disease resulting in an itchy eruption that can be persistent. Antihistamines and omalizumab, an anti-IgE mAb, are the only licensed therapies. Although CSU pathogenesis is not yet fully understood, mast cell activation through the IgE:high-affinity IgE receptor (FcεRI) axis appears central to the disease process.

OBJECTIVE

We sought to model CSU pathophysiology and identify in silico the mechanism of action of different CSU therapeutic strategies currently in use or under development.

METHODS

Therapeutic performance mapping system technology, based on systems biology and machine learning, was used to create a CSU interactome validated with gene expression data from patients with CSU and a CSU model that was used to evaluate CSU pathophysiology and the mechanism of action of different therapeutic strategies.

RESULTS

Our models reflect the known role of mast cell activation as a central process of CSU pathophysiology, as well as recognized roles for different therapeutic strategies in this and other innate and adaptive immune processes. They also allow determining similarities and differences between them; anti-IgE and Bruton tyrosine kinase inhibitors play a more direct role in mast cell biology through abrogation of FcεRI signaling activity, whereas anti-interleukins and anti-Siglec-8 have a role in adaptive immunity modulation.

CONCLUSION

In silico CSU models reproduced known CSU and therapeutic strategies features. Our results could help advance understanding of therapeutic mechanisms of action and further advance treatment research by patient profile.

Assessment of selected interleukins (IL-6, IL-17A, IL-18, IL-23) and chemokines (RANTES, IP-10) in children with acute and chronic urticaria

BACKGROUND

Urticarial lesions develop as a result of the activation of mast cells which, through the release of mediators, influence the formation of local inflammatory infiltrates. Changes in the expression of many cytokines and chemokines are observed in the course of urticaria. The aim of the study was to evaluate serum levels of interleukin (IL)-6, IL-17A, IL-18, IL-23, regulated on activation, normal T cell expressed and secreted (RANTES) and interferon (IFN)-γ-inducible protein-10 (IP-10) in children with acute urticaria and exacerbation of chronic urticaria in comparison to healthy volunteers. Moreover, we made an attempt to identify factors associated with the acute phase of urticaria and factors predicting the course of the disease among the studied parameters.

METHODS

We retrospectively analyzed 32 children with acute urticaria and 32 children with chronic urticaria. The control group consisted of 40 healthy children. Each patient was clinically evaluated. Serum concentrations of selected cytokines and chemokines were determined by using enzyme-linked immunosorbent assay.

RESULTS

Patients with acute and chronic urticaria had higher concentrations of IL-6 and IL-17A (p < 0.001) and lower concentrations of IL-18, IL-23, RANTES and IP-10 (p < 0.001) as compared to the control group. A significant association between IL-6 and IP-10 with the acute phase of urticaria has been demonstrated. There was no correlation of the studied cytokines and chemokines with disease activity.

CONCLUSIONS

In children with acute phase of urticaria, the cytokine serum concentration differs compared to healthy subjects. IL-6 and IP-10 seem to be useful in differentiating children with acute phase of urticaria and healthy ones. The search for factors predicting the course of the disease requires further studies.

Biologics for chronic spontaneous urticaria: toward a personalized treatment

INTRODUCTION

Chronic spontaneous urticaria (CSU) is characterized by the recurrent occurrence of short-lived wheals with or without angioedema for more than 6 weeks. Although its pathogenesis is not completely defined, several mechanisms seem involved, including autoimmunity and autoallergy with complement and coagulation activation. Various biologics are currently available or under investigation to counteract different CSU pathomechanisms.

AREAS COVERED

The recent literature dealing with biologics in the treatment of CSU was screened and analyzed; the different treatments were divided into anti-IgE and other than anti-IgE biologics. The latter were subdivided according to their target mechanisms.

EXPERT OPINION

Biologic drugs exert their effects in a very precise and specific manner. A majority of patients (arguably those with type I disease) respond to anti-IgE treatment. Others, possibly with type IIa disease, show a slow response to anti-IgE drugs. Things are much more complicated in anti-IgE-refractory patients. Some respond well to nonspecific immune suppressors, such as corticosteroids and cyclosporin suggesting that an immune-mediated pathogenic mechanism, not involving the high-affinity IgE receptor, is probably active. Several ongoing studies are evaluating biologics and small molecules counteracting other pathomechanisms, including anti-receptor biologics, Bruton tyrosine kinase (BTK) inhibitors, mast cell targets, and specific cytokines.

Integrated bioinformatics to identify potential key biomarkers for COVID-19-related chronic urticaria

Background

A lot of studies have revealed that chronic urticaria (CU) is closely linked with COVID-19. However, there is a lack of further study at the gene level. This research is aimed to investigate the molecular mechanism of COVID-19-related CU via bioinformatic ways.

Methods

The RNA expression profile datasets of CU (GSE72540) and COVID-19 (GSE164805) were used for the training data and GSE57178 for the verification data. After recognizing the shared differently expressed genes (DEGs) of COVID-19 and CU, genes enrichment, WGCNA, PPI network, and immune infiltration analyses were performed. In addition, machine learning LASSO regression was employed to identify key genes from hub genes. Finally, the networks, gene-TF-miRNA-lncRNA, and drug-gene, of key genes were constructed, and RNA expression analysis was utilized for verification.

Results

We recognized 322 shared DEGs, and the functional analyses displayed that they mainly participated in immunomodulation of COVID-19-related CU. 9 hub genes (CD86, FCGR3A, AIF1, CD163, CCL4, TNF, CYBB, MMP9, and CCL3) were explored through the WGCNA and PPI network. Moreover, FCGR3A, TNF, and CCL3 were further identified as key genes via LASSO regression analysis, and the ROC curves confirmed the dependability of their diagnostic value. Furthermore, our results showed that the key genes were significantly associated with the primary infiltration cells of CU and COVID-19, such as mast cells and macrophages M0. In addition, the key gene-TF-miRNA-lncRNA network was constructed, which contained 46 regulation axes. And most lncRNAs of the network were proved to be a significant expression in CU. Finally, the key gene-drug interaction network, including 84 possible therapeutical medicines, was developed, and their protein-protein docking might make this prediction more feasible.

Conclusions

To sum up, FCGR3A, TNF, and CCL3 might be potential biomarkers for COVID-19-related CU, and the common pathways and related molecules we explored in this study might provide new ideas for further mechanistic research.

New transcriptome and clinical findings of platelet-activating factor in chronic spontaneous urticaria: Pathogenic and treatment relevance

The objective of the study was to assess the pathogenic and treatment relevance of Platelet Activating factor (PAF) in chronic spontaneous urticaria (CSU). The expression and cellular location of PAF receptor (PAFR) and serum levels of PAF and PAF acetylhydrolase (PAF-AH) in patients with moderate/severe CSU (n = 45) and healthy controls (HCs, n = 17) were studied. Skin samples from the active wheal (LS-CSU, 13 samples for qPCR and 33 for immunohistochemistry) and non-lesional skin (NLS-CSU, 13 samples) of CSU patients and HCs (13 samples and 5 for immunohistochemistry) were analyzed. Serum PAF and PAF-AH levels were measured by ELISA and compared between HC (10 samples) and CSU patients (25 samples) and, among them, between those refractory and non-refractory to second-generation H₁ -antihistamines (sgAH). PAFR mRNA expression was significantly higher in LS-CSU versus HCs (p = 0.014). PAFR positive staining in immunohistochemistry was mainly found in the epidermal basal layer in HCs, whereas it was broadly present along the epidermis in LS-CSU samples. Endothelial cells showed PAFR expression exclusively in LS-CSU and NLS-CSU samples. PAFR expression was observed in the nerves of HC, LS-CSU, and NLS-CSU samples. Double PAFR/CD43 expression showed that T-lymphocytes were the main cell type from the wheal inflammatory infiltrate expressing PAFR. A significantly lower PAF-AH/PAF ratio was observed in sgAH non-responders versus responders (6.1 vs. 12.6; p = 0.049). Our study confirms that PAF is a mediator of wheal pathogenesis in CSU. The significantly lower PAF-AH/PAF ratio in sgAH non-responders vs responders suggests that PAF could be a potential biomarker of sgAH refractoriness.

Efficacy of Fangfeng Tongsheng Granule Combined with Levocetirizine in the Treatment of Chronic Urticaria and Its Effect on Serum Complement, IL-4, IgE, and IFN-γ Levels in Patients

Objectives

To investigate the efficacy of Fangfeng Tongsheng granule combined with levocetirizine in the treatment of chronic urticaria and its effect on serum complement, interleukin (IL)-4, immunoglobulin E (IgE), and interferon-γ (IFN-γ) levels in patients.

Methods

A total of 98 patients with chronic urticaria who were admitted to our hospital from July 2021 to March 2022 were selected and divided into random odd-even numbers. The odd numbers were included in the observation group, with a total of 49 cases, and they were treated with Fangfeng Tongsheng granule combined with levocetirizine; the even numbers were included in the control group, with a total of 49 cases and were treated with levocetirizine alone. The two groups of patients were treated continuously for 4 weeks, and the clinical efficacy of the two groups was observed. Before treatment, 2 weeks and 4 weeks after treatment, evaluate the clinical symptom scores of patients such as itching, flushing, wheal, edema, observe the improvement of clinical symptoms of patients, and the changes in Dermatology Life Quality Index (DLQI). Serum complement C3, C4, T lymphocyte subsets CD₃⁺, CD₄⁺, CD₈⁺ levels and CD₄⁺/CD₈⁺ ratio, IL-4, IgE, and IFN-γ levels and the occurrence of adverse reactions in the two groups were calculated and observed. All patients were followed up for 2 months after treatment to observe the recurrence of patients.

Results

The scores of clinical symptoms such as wheal, itching, flushing, edema, and attack frequency in the observation group at each time point after treatment were lower than those in the control group (F times were 725.365, 851.521, 936.411, 3943.136, and 2226.147, all P < 0.05 (F between-group were 40.642, 102.124, 188.523, 259.291, and 23.92, P < 0.05); the total effective rate of the observation group was 93.88% (46/49), which was significantly higher than that of the control group, 73.47% (36/49) (χ² = 7.470, P=0.006). The DLQI scores of the observation group at each time point after treatment were lower than those of the control group (F time was 282.214, P < 0.05; F between-group was 6.546, P < 0.05). There was no significant difference in serum C4 levels between the two groups at each time point (F time was 1.225, P > 0.05; F between-group was 0.408, P > 0.05); serum complement C3, CD₃⁺, and CD₄⁺/the ratio of CD₈⁺ and IFN-γ were higher than those in the control group (F time was 407.352, 107.823, 32.941, and 2354.147, P < 0.05; F between-group was 40.941, 24.710, 54.982, and 264.921, P < 0.05); the observation group at each time after treatment the levels of IgE and IL-4 were lower than those of the control group (F time were 373.124 and 395.612, P < 0.05; F between-group were 21.802 and 62.591, P < 0.05). The incidence of adverse reactions in the observation group was 12.24% (6/49) compared with 10.20% (5/49) in the control group, which had no significant difference (χ² = 0.102, P=0.749). Both groups were followed up for 2 months after treatment. The recurrence rate in the observation group was 12.24% (6/49), which was lower than that in the control group, which was 32.65% (16/49) (χ² = 5.861, P=0.015).

Conclusion

The application of Fangfeng Tongsheng granules combined with levocetirizine in patients with chronic urticaria can effectively improve the clinical symptoms of patients, improve clinical efficacy, reduce the impact of the disease on life, improve the immune status of patients, and reduce the risk of recurrence.

Basophils activation of patients with chronic spontaneous urticaria in response to C5a despite failure to respond to IgE-mediated stimuli

Urticaria is characterized by the occurrence of wheals and flares in response to vasoactive mediators, such as histamine. Various studies have suggested the involvement of basophils in the pathogenesis of chronic spontaneous urticaria (CSU). However, histamine release from peripheral basophils in response to stimuli acting on the high affinity IgE receptor (FcϵRI) is impaired in many patients with CSU (non/low responders). We previously demonstrated that tissue factor (TF)s expressed on vascular endothelial cells in response to a combination of various stimuli, such as that of histamine and lipopolysaccharide (LPS), activates the extrinsic coagulation pathway and produces anaphylatoxin, complement 5a (C5a), which then activates basophils and mast cells via the C5a receptor (C5aR). We have revealed that histamine release was induced in response to C5a and formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLP), regardless of the response to anti-IgE antibody, the reduced numbers of basophils and severity of urticaria. Moreover, we found that spontaneous release of histamine ex vivo from basophils of patients with CSU is higher than that from healthy individuals. These results suggest that basophils and the complement system, which could be activated by coagulation factors, may play a critical role in the pathogenesis of CSU, especially in cases refractory to treatment involving the IgE/FcϵRI pathway.

Urticaria

Urticaria is an inflammatory skin disorder that affects up to 20% of the world population at some point during their life. It presents with wheals, angioedema or both due to activation and degranulation of skin mast cells and the release of histamine and other mediators. Most cases of urticaria are acute urticaria, which lasts ≤6 weeks and can be associated with infections or intake of drugs or foods. Chronic urticaria (CU) is either spontaneous or inducible, lasts >6 weeks and persists for >1 year in most patients. CU greatly affects patient quality of life, and is linked to psychiatric comorbidities and high healthcare costs. In contrast to chronic spontaneous urticaria (CSU), chronic inducible urticaria (CIndU) has definite and subtype-specific triggers that induce signs and symptoms. The pathogenesis of CSU consists of several interlinked events involving autoantibodies, complement and coagulation. The diagnosis of urticaria is clinical, but several tests can be performed to exclude differential diagnoses and identify underlying causes in CSU or triggers in CIndU. Current urticaria treatment aims at complete response, with a stepwise approach using second-generation H1 antihistamines, omalizumab and cyclosporine. Novel treatment approaches centre on targeting mediators, signalling pathways and receptors of mast cells and other immune cells. Further research should focus on defining disease endotypes and their biomarkers, identifying new treatment targets and developing improved therapies.

Asian herbal medicine and chronic urticaria: which are the therapeutic perspectives?

Chronic urticaria (CU) is a pathologic condition marked by the emergence of wheals, angioedema, or both for more than six weeks. The improper activation and degranulation of mast cells is the triggering event, which results in the production of various mediators such as histamine, leukotrienes, PAF, chemokines, and cytokines. Antihistamines are currently the most common pharmacological treatment for urticaria, but corticosteroids and monoclonal antibodies can also be employed. Patients who have been taking antihistamines for a long time are often looking for alternatives. Whole plants, portions of plants, or single extracted active compounds are all used in phytomedicine. Plant elements are frequently combined to create formulations that can be utilized to treat a variety of pathological disorders. Anti-inflammatory and/or anti-allergic properties are found in several herbs regularly used in herbal formulations. Antioxidant properties are also present in some of the constituents. Exogenous antioxidants have been shown to improve the progression of autoimmune disorders in numerous studies. The aim of this review is to identify the most common herbs used to treat chronic urticaria, and to characterize their efficacy, mechanisms of action, and risk/benefit ratio in comparison to western treatment, and also to find less often used formulations and assess their therapeutic efficacy, safety profile, and potential for wider use.

Serum Levels of Vascular Endothelial Growth Factor, Platelet Activating Factor and Eosinophil-Derived Neurotoxin in Chronic Spontaneous Urticaria—A Pilot Study in Adult Patients

Chronic spontaneous urticaria (CSU) is a skin disease characterized by the presence of wheals, angioedema, or both for at least 6 weeks. Although, CSU is often regarded as autoimmune in nature, its etiology is not fully explained and interactions between various small molecules are still taken under account. The aim of this research was to investigate the mean serum concentration of vascular endothelial growth factor (VEGF), platelet activating factor (PAF), and eosinophil-derived neurotoxin (EDN) in relation to the disease activity and pruritus intensity in adult patients with CSU. Fifteen patients with CSU and 15 healthy subjects participated in this pilot study. Blood samples were taken to examine the mean serum levels of VEGF, PAF, and EDN by the enzyme-linked immunosorbent assay test (ELISA). The Urticaria Activity Score (UAS7) and The Visual Analogue Scale (VAS) were used to assess the disease activity and the pruritus intensity, respectively. Obtained results revealed that VEGF, PAF, and EDN concentrations were higher in patients with CSU compared with those of the control group, but only for VEGF it was statistically significant (p = 0.008). However, levels of all investigated cytokines were not significantly correlated neither with the disease activity nor with the pruritus intensity. Our results showed higher serum levels of VEGF, PAF, and EDN among CSU patients which may highlight a functional role of these cytokines in the disease’s pathogenesis. In contrast, VEGF, PAF, or EDN might not be useful to reflect the severity of symptoms.

Detection of serum IgG autoantibodies to FcεRIα by ELISA in patients with chronic spontaneous urticaria

Background

Mast cells are a key effector cell in the pathogenesis of chronic spontaneous urticaria (CSU) and activated by circulating FcεRI-specific IgG as well as IgE. This study evaluated the prevalence of circulating autoantibodies to FcεRIα in the sera of CSU patients.

Methods

Eighty-eight patients with CSU and 76 healthy controls (HCs) were enrolled. To detect circulating autoantibodies (IgG/IgA/IgM) to FcεRIα, ELISA was done using YH35324 (as a solid phase antigen), and its binding specificity was confirmed by the ELISA inhibition test. The antibody levels were presented by the ratio of YH35324-preincubated to mock-preincubated absorbance values. Clinical and autoimmune parameters, including atopy, urticaria activity score (UAS), serum total/free IgE levels, serum antinuclear antibody (ANA) and autologous serum skin test (ASST) results, were assessed. The autoimmune group was defined if CSU patients had positive results to ASST and/or ANA.

Results

The ratio of serum IgG to FcεRIα was significantly lower in CSU patients than in HCs (P<0.05), while no differences were noted in serum levels of IgG to recombinant FcεRIα or IgA/IgM autoantibodies. The autoimmune CSU group had significantly lower ratios of IgG/IgA (not IgM) autoantibodies to FcεRIα than the nonautoimmune CSU group (P<0.05 for each). No significant associations were found between sex, age, atopy, urticaria duration, UAS, or serum total/free IgE levels according to the presence of IgG/IgA/IgM antibodies.

Conclusions

This study confirmed the presence of IgG to FcεRIα in the sera of CSU patients, especially those with the autoimmune phenotype.

In silico Identification of Immune Cell-Types and Pathways Involved in Chronic Spontaneous Urticaria

Background

The immunopathogenesis of chronic spontaneous urticaria (CSU) is poorly understood, but recent research suggests that patients can be divided into autoallergic and autoimmune subtypes. Given that not all patients can be controlled with current treatment regimens, including anti-IgE monoclonal antibodies, a better understanding of the immune pathways involved in CSU may enable the repurposing of monoclonal antibodies used for other dermatologic diseases (e.g., Th2 and Th17 inhibitors). Therefore, we investigated the implicated immune cells and pathways by reanalyzing publicly available transcriptomic data.

Methods

Microarray data of CSU and healthy control (HC) skin and blood were obtained from the Gene Expression Omnibus (GSE72542, GSE57178). Differentially expressed genes were defined as a false discovery rate <0.05 and a |log₂ fold change| ≥1. Pathway analyses were conducted using ToppGene and KEGG. Cell-type enrichment was determined by CIBERSORT and xCell and was correlated with clinical characteristics.

Results

Th2 (IL-4/13 signaling) and Th17-related (IL-17/23 signaling) pathways were upregulated in lesional compared to non-lesional and HC samples. In non-lesional versus lesional samples, CIBERSORT analysis revealed increased regulatory T-cells (Treg) and resting mast cells. xCell analysis established that Th1 and Th2 scores were not significantly different between lesional and HC samples. However, Th2 scores in both lesional and non-lesional samples correlated positively with disease severity. Few differentially expressed genes and pathways were identified between CSU and HC blood samples.

Conclusion

Our results support the involvement of Th2 and Th17-related genes and pathways in CSU. Th2 scores associate with disease severity, which indicates the clinical relevance of these findings. Increased resting mast cell and Treg scores in non-lesional samples may suggest local suppression of wheal formation. Moreover, disease activity seemed to be restricted to the skin as there were limited findings from blood. Larger studies using next-generation sequencing will be helpful to confirm these results.

The Intersection of Acute Kidney Injury and Non-Coding RNAs: Inflammation

Acute renal injury (AKI) is a complex clinical syndrome, involving a series of pathophysiological processes, in which inflammation plays a key role. Identification and verification of gene signatures associated with inflammatory onset and progression are imperative for understanding the molecular mechanisms involved in AKI pathogenesis. Non-coding RNAs (ncRNAs), involved in epigenetic modifications of inflammatory responses, are associated with the aberrant expression of inflammation-related genes in AKI. However, its regulatory role in gene expression involves precise transcriptional regulation mechanisms which have not been fully elucidated in the complex and volatile inflammatory response of AKI. In this study, we systematically review current research on the intrinsic molecular mechanisms of ncRNAs that regulate the inflammatory response in AKI. We aim to provide potential research directions and strategies for developing ncRNA-targeted gene therapies as an intervention for the inflammatory damage in AKI.

The Putative Role of Astaxanthin in Neuroinflammation Modulation: Mechanisms and Therapeutic Potential

Neuroinflammation is a protective mechanism against insults from exogenous pathogens and endogenous cellular debris and is essential for reestablishing homeostasis in the brain. However, excessive prolonged neuroinflammation inevitably leads to lesions and disease. The use of natural compounds targeting pathways involved in neuroinflammation remains a promising strategy for treating different neurological and neurodegenerative diseases. Astaxanthin, a natural xanthophyll carotenoid, is a well known antioxidant. Mounting evidence has revealed that astaxanthin is neuroprotective and has therapeutic potential by inhibiting neuroinflammation, however, its functional roles and underlying mechanisms in modulating neuroinflammation have not been systematically summarized. Hence, this review summarizes recent progress in this field and provides an update on the medical value of astaxanthin. Astaxanthin modulates neuroinflammation by alleviating oxidative stress, reducing the production of neuroinflammatory factors, inhibiting peripheral inflammation and maintaining the integrity of the blood-brain barrier. Mechanistically, astaxanthin scavenges radicals, triggers the Nrf2-induced activation of the antioxidant system, and suppresses the activation of the NF-κB and mitogen-activated protein kinase pathways. With its good biosafety and high bioavailability, astaxanthin has strong potential for modulating neuroinflammation, although some outstanding issues still require further investigation.

Plasma-derived exosomes in chronic spontaneous urticaria induce the production of mediators by human mast cells

Mast cell activation and inflammatory mediators play central roles in the pathogenesis of chronic spontaneous urticaria (CSU). The factors that induce mast cell activation in CSU are still largely unknown. Exosomes are extracellular vesicles that activate mast cells. Here, we enriched exosomes derived from the plasma of healthy volunteers and CSU patients with antihistamine sensitivity (EXs-CSU-S) or resistance (EXs-CSU-R) using ultracentrifugation. We then incubated these exosomes with HMC-1 human mast cells. Notably, EXs-CSU-S and EXs-CSU-R increased tryptase-1 expression; histamine production; inflammatory mediator production; and Toll-like receptor-2 (TLR-2), TLR-4, and phospho-mitogen-activated protein kinase (MAPK) levels in HMC-1 cells. These effects were more significant in the EXs-CSU-R group than in the EXs-CSU-S group. TLR-2, TLR-4, and MAPK inhibitors (CC-401, TAK-715, and SCH772984, respectively) reduced EXs-CSU-Stimulated production of inflammatory mediators in HMC-1 cells. Overall, exosomes in the plasma of patients with CSU were found to activate mast cells and elicit the production of multiple inflammatory mediators, partly via the TLR-2, TLR-4, and MAPK pathways. Additionally, EXs-CSU-R had more powerful mast cell-activating and histamine-release abilities. Thus, these exosomes may be involved in the pathogenesis of CSU with antihistamine resistance.

The Role of Crosstalk of Immune Cells in Pathogenesis of Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is defined as recurrent episodes of spontaneous wheal development and/or angioedema for more than six weeks and at least twice a week. The core link in the pathogenesis of CSU is the activation of mast cells, T cells, eosinophils, and other immune cells infiltrating around the small venules of the lesion. Increased vascular permeability, vasodilatation, and recruitment of inflammatory cells directly depend on mast cell mediators’ release. Complex regulatory systems tightly influence the critical roles of mast cells in the local microenvironment. The bias toward Th2 inflammation and autoantibodies derived from B cells, histamine expressed by basophils, and initiation of the extrinsic coagulation pathway by eosinophils or monocytes exerts powerful modulatory influences on mast cells. Cell-to-cell interactions between mast cells and eosinophils/T cells also are regulators of their function and may involve CSU’s pathomechanism. This review summarizes up-to-date knowledge regarding the crosstalk between mast cells and other immune cells, providing the impetus to develop new research concepts and treatment strategies for CSU.

Urticarial vasculitis: Clinical and laboratory findings with a particular emphasis on differential diagnosis

Urticarial vasculitis (UV) is a rare cutaneous vasculitis of small vessels characterized by recurrent episodes of wheal-like lesions that tend to last more than 24 hours, healing with a residual ecchymotic postinflammatory hyperpigmentation. The histopathologic pattern of UV is that of leukocytoclastic vasculitis, consisting of fibrinoid necrosis of dermal vessels' walls and neutrophil-rich perivascular inflammatory infiltrates. Although its etiopahogenesis remains still undefined, UV is now regarded as an immune complex-driven disease with activation of the complement cascade, leading to exaggerated production of anaphylatoxins that are responsible for neutrophil recruitment and activation. This condition can be categorized into 2 main entities according to serum complement levels: normocomplementemic UV and hypocomplementemic UV, the latter being associated with circulating anti-C1q autoantibodies and possible extracutaneous manifestations. Systemic multiorgan involvement may be seen particularly in syndromic hypocomplementemic UV, also known as McDuffie syndrome. This review summarizes the clinicopathological and laboratory features as well as the underlying pathophysiological mechanisms of UV. A focus on its main differential diagnoses is provided, that is, chronic spontaneous urticaria, bullous pemphigoid, IgA (Henoch-Schönlein purpura) and IgM/IgG immune complex vasculitis, lupus erythematous tumidus, Wells syndrome, erythema multiforme, cutaneous mastocytosis, cryopyrin-associated periodic syndromes, and coronavirus disease 2019-associated and anti-severe acute respiratory syndrome coronavirus 2-vaccine-associated urticarial eruptions.

Effects of Vaccination against COVID-19 in Chronic Spontaneous and Inducible Urticaria (CSU/CIU) Patients: A Monocentric Study

Background: Patients affected by pre-existing chronic spontaneous/Inducible urticaria (CSU/CIU) still feel unsafe due to the potential risk of an Adverse Event Following Immunization (AEFI) and Cutaneous Adverse Reactions (CARs) of COVID-19 vaccines. The appropriate management in this field remains debated and evidence is still lacking. Methods: We considered 160 CSU/CIU patients in Omalizumab/antihistamine therapy who received two doses of Comirnaty/Moderna mRNA vaccines; 20 of them also received a booster dose. Urticaria Activity Score-7 (UAS7) was used to assess the severity of the disease. Demographics, medical history, AEFI and CARs outcome after vaccination were collected by administering a web-based questionnaire completed by phone interview. Results: In total, 147 patients did not show urticaria relapse (91.88%). Worsening cutaneous symptoms were experienced by 13 of our patients (8.12%). Exacerbation had a mean duration of 2 days and 11 h and mostly occurred after the first dose (69.23%). Systemic mild side effects were experienced by 9 patients (5.62%). No severe reactions were observed. Conclusions: Omalizumab can potentially prevent CARs and AEFI; however, major problems were registered during the 2-month stop period scheduled in the treatment. We suggest patients should not undergo vaccination during this period. CSU/CIU exacerbations appear to be transient and can be managed by antihistamines.

Integrated Bioinformatics and Validation Reveal IL1B and Its Related Molecules as Potential Biomarkers in Chronic Spontaneous Urticaria

Background

The etiopathogenesis of chronic spontaneous urticaria (CSU) has not been fully understood, and there has been extensive interest in the interaction between inflammatory dermatosis and pyroptosis. This study intends to investigate the molecular mechanism of pyroptosis-related genes in CSU via bioinformatic ways, aiming at identifying the potential key biomarker.

Methods

GSE72540, the RNA expression profile dataset of CSU, was utilized as the training set, and GSE57178 as the validation set. Differently expressed pyroptosis-related genes (DEPRGs), GO, KEGG, and DO analyses were performed. The hub genes were explored by the protein–protein interaction analysis. Moreover, CIBERSORT was employed for estimating immune cell types and proportions. Then, we constructed a DEmRNA–miRNA–DElncRNA ceRNA network and a drug–gene interaction network. Finally, ELISA was used for gene expression analysis.

Results

We recognized 17 DEPRGs, whose enrichment analyses showed that they were mostly enriched in inflammatory response and immunomodulation. Moreover, 5 hub genes (IL1B, TNF, and IRF1 are upregulated, HMGB1 and P2RX7 are downregulated) were identified via the PPI network and verified by a validation set. Then immune infiltration analysis displayed that compared with normal tissue, CSU owned a significantly higher proportion of mast cells activated, but a lower proportion of T cells CD4 naive and so on. Furthermore, IL1B was statistically and positively associated with mast cells activated in CSU, and SNHG3, the upstream factor of IL1B in the ceRNA we constructed, also related with mast cells in CSU. Further analysis exhibited that the protein subcellular localization of IL1B was extracellular, according with its intercellular regulation role; IL1B was significantly correlated with key immune checkpoints; and the NOD-like receptor signaling pathway was the mainly involved pathway of IL1B based on the couple databases. What is more, the result of ELISA of CSU patients was the same as the above analyses about IL1B. In addition, the drug–gene interaction network contained 15 potential therapeutic drugs targeting IL1B, and molecular docking might make this relationship viable.

Conclusion

IL1B and its related molecules might play a key role in the development of CSU and could be potential biomarkers in CSU.

Analysis of the Transcriptional Activity of Immune Response Genes in the Blood of Patients with Acute Urticaria

OBJECTIVE: Alterations in the transcriptional activity of some immunoregulatory genes can play a key in the pathogenesis of acute urticarial (AU). Minimally-invasive markers of the transcriptional activity of immune response genes are essential not only for predicting the severity and activity of the disease but also as a potential target for therapy. METHODS: In our research, we applied a pathway-specific polymerase chain reaction PCR array (Human Innate and Adaptive Immune Responses RT2 Profiler PCR Array, QIAGEN, Germany) to detect and verify innate and adaptive immune responses pathway-focused genes expression in patients suffering from AU and control group. RESULTS: The AU development was accompanied by an increase in the transcriptional activity of genes for a number of costimulation molecules such as CD40, CD40LG, CD80 (B7-1), and C-reactive protein and myeloperoxidase genes either. Under AU conditions, transcriptional induction of genes of several cytokines was also observed: Interferon gamma, interleukin (IL4), IL5, IL17A, tumor necrosis factor, and also chemokine CXCL8. This process was also accompanied by an increase in the transcriptional activity of the RAR-related orphan receptor C Th17 differentiation regulator, the NLRP3 inflammasome genes, and the NFKB1 transcription factor. Such changes occurred against the background of transcriptional repression of the FOXP3 gene and the Treg-dependent suppressor cytokine IL10. The expression of other studied genes did not differ significantly from the controls. CONCLUSIONS: The development of acute urticaria led to the transcriptional activation of pro-inflammatory signaling against the background of a deficiency of the suppressor link. Detected changes in gene expression can be important for targeted therapy.

Cold urticaria in a pediatric cohort: Clinical characteristics, management, and natural history

BACKGROUND

Cold urticaria (coldU) is associated with substantial morbidity and risk of fatality. Data on coldU in children are sparse. We aimed to evaluate the clinical characteristics, management, risk of associated anaphylaxis, and resolution rate of coldU in a pediatric cohort. Additionally, we sought to compare these metrics to children with chronic spontaneous urticaria (CSU).

METHODS

We prospectively enrolled children with coldU from 2013-2021 in a cohort study at the Montreal Children's Hospital and an affiliated allergy clinic. Data for comparison with participants with solely CSU were extracted from a previous study. Data on demographics, comorbidities, severity of presentation, management, and laboratory values were collected at study entry. Patients were contacted yearly to assess for resolution.

RESULTS

Fifty-two children with cold urticaria were recruited, 51.9% were female and the median age of symptom onset was 9.5 years. Most patients were managed with second-generation H1-antihistamines (sgAHs). Well-controlled disease on sgAHs was negatively associated with concomitant CSU (adjusted odds ratio (aOR) = 0.69 [95%CI: 0.53, 0.92]). Elevated eosinophils were associated with cold-induced anaphylaxis (coldA; aOR = 1.38 [95%CI: 1.04, 1.83]), which occurred in 17.3% of patients. The resolution rate of coldU was 4.8 per 100 patient-years, which was lower than that of CSU (adjusted hazard ratio = 0.43 [95%CI: 0.21, 0.89], p < 10^-2 ).

CONCLUSION

Pediatric coldU bears a substantial risk of anaphylaxis and a low-resolution rate. Absolute eosinophil count and co-existing CSU may be useful predictive factors.

Emerging treatments for chronic urticaria

INTRODUCTION

Across the globe, chronic urticaria (CU), i.e. chronic spontaneous urticaria (CSU) and chronic inducible urticaria (CINDU), is common, long-persisting and difficult to manage. Still, at least one-fifth is not sufficiently controlled by guideline-recommended treatment with H1-antihistamines and add-on therapy with the anti-IgE monoclonal antibody omalizumab.

AREAS COVERED

Using PubMed, ClinicalTrials.gov, Congress websites, and websites of the manufacturers, this review explored the pipeline, namely anti-IgE-, anti-cytokine-, anti-receptor biologics, and small molecules, in clinical development for CU.

EXPERT OPINION

The CU pipeline is promising. While three omalizumab biosimilars are investigated, the assumed early approval of ligelizumab will expand the effective and safe anti-IgE approach observed with omalizumab. For other anti-IgEs like UB-221, the development is behind. Data are too limited so far to clearly define the role of anti-cytokine and anti-cytokine receptor biologics such as dupilumab, tezepelumab, mepolizumab, benralizumab, and CDX-0159, of which only dupilumab is actually investigated in phase 3. Among three selective oral BTK inhibitors, remibrutinib, rilzabrutinib, and fenebrutinib, the development of remibrutinib is most advanced (phase 3). As the pipeline addresses different targets, study results will give deeper insights into the pathomechanisms of CU. Hopefully, in the next future additional approved and also more targeted approaches will be available.

Long-term follow-up of patients treated with dupilumab for chronic spontaneous urticaria: A case report

Several therapeutic strategies have been established to achieve maximal remission and improve quality of life in patients with chronic spontaneous urticaria. We previously reported dupilumab as a novel therapy for antihistamine-refractory chronic spontaneous urticaria patients who failed to respond to administration of omalizumab at increased doses for longer durations. This is the first case series to report data on the long-term duration of chronic spontaneous urticaria remission after discontinuation of dupilumab in patients who were able to obtain controlled chronic spontaneous urticaria. Six patients diagnosed with chronic spontaneous urticaria, who failed to respond to antihistamines and prolonged therapy with omalizumab at increased doses, were followed in this study for up to 34 months following initiation of dupilumab therapy. By demonstrating the maintenance of chronic spontaneous urticaria remission with dupilumab following discontinuation of therapy, in 67% of the patients, over an observation period up to 22 months, this case series highlights dupilumab’s potential disease-modifying efficacy in patients affected by this disease.

The Role of Coagulation and Complement Factors for Mast Cell Activation in the Pathogenesis of Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is a common skin disorder characterized by an almost daily recurrence of wheal and flare with itch for more than 6 weeks, in association with the release of stored inflammatory mediators, such as histamine, from skin mast cells and/or peripheral basophils. The involvement of the extrinsic coagulation cascade triggered by tissue factor (TF) and complement factors, such as C3a and C5a, has been implied in the pathogenesis of CSU. However, it has been unclear how the TF-triggered coagulation pathway and complement factors induce the activation of skin mast cells and peripheral basophils in patients with CSU. In this review, we focus on the role of vascular endothelial cells, leukocytes, extrinsic coagulation factors and complement components on TF-induced activation of skin mast cells and peripheral basophils followed by the edema formation clinically recognized as urticaria. These findings suggest that medications targeting activated coagulation factors and/or complement components may represent new and effective treatments for patients with severe and refractory CSU.