Neuro-Immuno-Psychological Aspects of Chronic Urticaria

Unraveling the causative connection between urticaria, inflammatory cytokines, and mental disorders: Perspectives from genetic evidence

BACKGROUND

The genetic association between urticaria and mental disorders and whether inflammatory cytokines mediate this process remains unclear.

MATERIALS AND METHODS

A Mendelian randomization (MR) approaches to elucidate the causal relationship between urticaria and mental disorders and to validate the mediation of inflammatory cytokines. Genome-wide association study (GWAS) databases used were obtained from Psychiatric Genomics Cooperation (PGC), GWAS Catalog, and FinnGen Consortium. Our study was conducted using inverse variance weighted (IVW) and Bayesian weighted MR (BWMR) methods for joint analysis.

RESULTS

The MR results showed that urticaria increased the risk of attention deficit hyperactivity disorder (ADHD) (odds ratio [OR] = $ = $ 1.088, 95% confidence interval [CI]: 1.026-1.154, p = $ = $ 0.0051); cholinergic urticaria increased the risk of bipolar disorder (BD) (OR = $ = $ 1.012, 95% CI: 1.001-1.022, p = $ = $ 0.0274); dermatographic urticaria increased the risk of ADHD (OR = $ = $ 1.057, 95% CI: 1.005-1.112, p = $ = $ 0.0323); idiopathic urticaria increased the risk of schizophrenia (SCZ) (OR = $ = $ 1.057, 95% CI: 1.005-1.112, p = $ = $ 0.0323); other unspecified urticaria increased the risk of ADHD (OR = $ = $ 1.085, 95% CI: 1.023-1.151, p = $ = $ 0.0063). We found that eight inflammatory cytokines were negatively associated with mental disorders and seven inflammatory cytokines were positively associated with mental disorders. Finally, our results suggested that inflammatory cytokines do not act as mediators between urticaria and mental disorders.

CONCLUSIONS

Our study reveals a causal relationship between urticaria and the increased risk of mental disorders. We suggest that the treatment of urticaria could incorporate psychiatric interventions and mental health assessment of patients.

Shedding light on dermographism: a narrative review

Dermographism is a common subtype of chronic urticaria. It generally manifests as a linear wheal after scratching or friction, with or without angioedema. The pathophysiology is not clear, but currently, we believe that the stimulation of the skin by mechanical stress leads to the activation of mast cells, which provoke the release of histamine and pro-inflammatory mediators, ultimately forming wheal along the stressed area. The gold standard for diagnosis is a medical history and provocation test or dermatographic test. As one of the subtypes of chronic urticaria, the Urticaria Control Test (UCT), Chronic Urticaria Quality of Life questionnaire (CU-Q2oL), and Dermatology Life Quality Index (DLQI) are also effective tools for evaluating disease control in dermographism patients. In addition to avoiding triggers, nonsedating H1 antihistamines are the first-line medications recommended by EAACI and other guidelines; for those who do not respond to standard doses, the recommended dosage can be increased up to 4 times. When necessary, the off-label use of omalizumab can be considered, and some drugs with potential therapeutic effects are still being explored. However, there is still a lack of biomarkers for predicting disease severity, efficacy, and prognosis. Here, we review what we know about dermographism and some points that need exploration in the future.

Efficacy and Mechanism of Acupoint Catgut Embedding in the Treatment of Chronic Spontaneous Urticaria: Protocol for a Randomized Double-Blind Placebo-Controlled Trial

BACKGROUND

Chronic spontaneous urticaria (CSU) is a common chronic inflammatory skin disease that manifests as itching and wheals, seriously affecting quality of life. Clinical observations and previous research trials have shown that acupuncture is safe and effective for the treatment of CSU. However, there are problems, such as a short duration of action and frequent treatment. Compared with traditional acupuncture, acupoint catgut embedding (ACE) has the advantages of a longer effect and higher compliance. Clinical trials are needed to prove its efficacy and mechanism of action.

OBJECTIVE

This trial aims to provide definitive evidence for the treatment of CSU with ACE and explore the mechanism of ACE.

METHODS

This is a randomized, double-blind, placebo-controlled trial. In this trial, 108 participants aged 18-60 years with a diagnosis of CSU and no history of ACE will be randomly assigned to 2 groups (1:1 ratio) using the Statistical Analysis System: treatment (ACE) and control (sham ACE). The participants and efficacy evaluators will be blinded to the grouping. Both the ACE and sham ACE groups will undergo acupuncture, but the sham ACE group will not receive catgut sutures. Treatment will be performed twice weekly for 8 weeks, with a 1-week run-in period and a 16-week follow-up period. Twenty patients will be randomly selected to undergo functional magnetic resonance imaging before and after the treatment period. The primary outcome will be the urticaria activity score over 7 days (UAS7). We will use R (version 4.0.1; R Project for Statistical Computing) to perform ANOVA and independent samples t tests to compare the differences within and between groups before and after treatment by judging the rejection range based on a significance level of .05.

RESULTS

The study protocol has been approved by the Ethics Committee of Guang'anmen Hospital on September 7, 2022, and has been registered on November 30, 2022. Recruitment began on March 1, 2023. A total of 4-6 participants are expected to be recruited each month. The recruitment is planned to be completed on March 1, 2025, and we expect to publish our results by the winter of 2025. As of November 1, 2023, we have enrolled 25 participants with CSU.

CONCLUSIONS

This randomized, double-blind, placebo-controlled trial aims to provide definitive evidence for the treatment of CSU with ACE and explore the mechanism of ACE. We hypothesize that wheals and itching will show greater improvement in participants receiving active therapy than in those receiving sham treatment. The limitations of this study include its single-center trial design, small sample size, and short treatment duration, which may have certain impacts on the research results.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200066274; https://www.chictr.org.cn/showprojEN.html?proj=179056.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/54376.

Associations of Gut and Circulating Microbiota with Circulating Vitamin D3, Type I Interferon, and Systemic Inflammation in Chronic Spontaneous Urticaria Patients

Objective

To analyze the associations of the gut and circulating microbiota with circulating vitamin D3 (VD3), type I interferon (IFNI), systemic inflammation, and clinical profiles in chronic spontaneous urticaria (CSU) patients.

Methods

A total of 36 CSU patients with VD3 insufficiency (VDI; serum 25(OH)VD3 <30 ng/mL) and 36 sex-, age-, and body mass index-matched CSU patients with non-VDI were enrolled. Fecal and serum bacteria were identified through 16S rRNA sequencing, and serum 25(OH)VD3 and inflammation biomarkers were assessed using ELISA kits. IFNI response was determined by measuring the stimulatory activity of serum on IFNI-stimulated response element in HEK293 cells in vitro with luciferase assays.

Results

Higher urticarial activity score over 7 days (UAS7), higher frequency of levocetirizine resistance, and more severe proinflammation but weaker IFNI response were observed in VDI than non-VDI patients (all P<0.05). IFNI response was strongly positively associated with serum 25(OH)VD3 level in both groups (P<0.001). Compared to non-VDI patients, abundance of the fecal genera Prevotella 9, Escherichia-Shigella, and Klebsiella was significantly increased, while Bacteroides, Faecalibacterium, and Agathobacter were remarkably reduced in VDI patients (all P<0.05). Burkholderia-Caballeronia-Paraburkholderia (40.95%), Acinetobacter (3.05%), and Aquabacterium (2.37%) were the top three bacteria in sera from VDI patients. Both serum 25(OH)VD3 level and IFNI response were positively associated with fecal Bacteroides in the two groups (P<0.05). In non-VDI patients, there were moderately positive associations between IFNI response and fecal Lachnoclostridium, unclassified_f__Lachnospiraceae, and Phascolarctobacterium and between serum 25(OH)VD3 level and fecal Lachnoclostridium (all P<0.01). Circulating microbiota in VDI patients was closely related only to proinflammation and UAS7 (both P<0.05).

Conclusion

Changes in gut but not circulating microbiota composition are associated with serum 25(OH)VD3 insufficiency and impaired IFNI homeostasis, which points to greater disease severity (UAS7) and systemic proinflammation in CSU patients.

Identification of key genes and molecular mechanisms of chronic urticaria based on bioinformatics

Chronic urticaria (CU) is characterized by persistent skin hives, redness, and itching, enhanced by immune dysregulation and inflammation. Our main objective is identifying key genes and molecular mechanisms of chronic urticaria based on bioinformatics. We used the Gene Expression Omnibus (GEO) database and retrieved two GEO datasets, GSE57178 and GSE72540. The raw data were extracted, pre-processed, and analyzed using the GEO2R tool to identify the differentially expressed genes (DEGs). The samples were divided into two groups: healthy samples and CU samples. We defined cut-off values of log2 fold change ≥1 and p < .05. Analyses were performed in the Kyoto Encyclopaedia of Genes and Genomes (KEGG), the Database for Annotation, Visualization and Integrated Discovery (DAVID), Metascape, Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and CIBERSOFT databases. We obtained 1613 differentially expressed genes. There were 114 overlapping genes in both datasets, out of which 102 genes were up-regulated while 12 were down-regulated. The biological processes included activation of myeloid leukocytes, response to inflammations, and response to organic substances. Moreover, the KEGG pathways of CU were enriched in the Nuclear Factor-Kappa B (NF-kB) signaling pathway, Tumor Necrosis Factor (TNF) signaling pathway, and Janus kinase/signal transducers and activators of transcription (JAK-STAT) signaling pathway. We identified 27 hub genes that were implicated in the pathogenesis of CU, such as interleukin-6 (IL-6), Prostaglandin-endoperoxide synthase 2 (PTGS2), and intercellular adhesion molecule-1 (ICAM1). The complex interplay between immune responses, inflammatory pathways, cytokine networks, and specific genes enhances CU. Understanding these mechanisms paves the way for potential interventions to mitigate symptoms and improve the quality of life of CU patients.

[Recognition and management of relevant comorbidities in chronic spontaneous urticaria]

Various mechanisms contributing to the activity of chronic spontaneous urticaria (CU) have been postulated. Associated comorbidities are increasingly leading to the discovery of further signaling pathways which may support the activity of chronic urticaria or contribute to low-grade systemic inflammation. Moreover psychoimmunological factors may also be involved. The aim of this work is to improve the clinical care of patients with CU by increasing knowledge regarding optional influencing factors due to comorbidities and to possibly influence disease activity. Chronic urticaria due to autoimmune mechanisms may dispose to other autoimmune diseases, especially autoimmune thyroiditis, which can trigger chronic disease. Association of CU with metabolic syndrome has received little attention to date. Obesity may contribute to low-grade systemic inflammation by cytokine-secreting adipose tissue and hence to mediator-release of mast cells. Furthermore, neuroimmunological pathways, especially increased release of substance P, an activating ligand of Mas-related G protein-coupled receptor X2 (MRGPX2) on mast cells, should be addressed when optimizing therapy.

[Mast Cell-Neutrophil Communication Regulates Allergic Diseases]

Allergic diseases (e.g., food allergies) are a growing problem, with increasing numbers of individuals experiencing them worldwide. Congruently, the adverse reactions (e.g., anaphylaxis) associated with the administration of vaccines against emerging infectious diseases such as coronavirus disease 2019 (COVID-19) have become a familiar problem. Allergic diseases, which have a wide variety of symptoms, are difficult to prevent or cure; treatment is currently limited to therapeutic drugs or allergen immunotherapy. Therefore, elucidating new allergic regulatory factors that control the allergic (i.e., mast cell) responses is important. While investigating the regulatory mechanisms of the wide range of allergic responses of mast cells, we found that the affinity of allergens to immunoglobin E (IgE) regulates allergic inflammation through the differences in the secretory responses of mast cells and the types and interactions of the cells infiltrating the tissues. Here, we present our recent findings regarding the affinity of allergens to IgE in regulating allergic inflammation, heterogeneous secretory granules inducing diverse secretory responses, and mast cells interacting with neutrophils, thereby regulating the various allergic responses.

A Patient Charter for Chronic Urticaria

Chronic urticaria (CU) is the recurring development of wheals (aka "hives" or "welts"), angioedema, or both for more than 6 weeks. Wheals and angioedema occur with no definite triggers in chronic spontaneous urticaria, and in response to known and definite physical triggers in chronic inducible urticaria. Approximately 1.4% of individuals globally will have CU during their lifetime. The itching and physical discomfort associated with CU have a profound impact on daily activities, sexual function, work or school performance, and sleep, causing significant impairment in a patient's physical and mental quality of life. CU also places a financial burden on patients and healthcare systems. Patients should feel empowered to self-advocate to receive the best care. The voice of the patient in navigating the journey of CU diagnosis and management may improve patient-provider communication, thereby improving diagnosis and outcomes. A collaboration of patients, providers, advocacy organizations, and pharmaceutical representatives have created a patient charter to define the realistic and achievable principles of care that patients with CU should expect to receive. Principle (1): I deserve an accurate and timely diagnosis of my CU; Principle (2): I deserve access to specialty care for my CU; Principle (3): I deserve access to innovative treatments that reduce the burden of CU on my daily life; Principle (4): I deserve to be free of unnecessary treatment-related side-effects during the management of my CU; and Principle (5): I expect a holistic treatment approach to address all the components of my life impacted by CU. The stated principles may serve as a guide for healthcare providers who care for patients with CU and translate into better patient-physician communication. In addition, we urge policymakers and authors of CU treatment guidelines to consider these principles in their decision-making to ensure the goals of the patient are achievable.

Biomarkers of Autoimmune Chronic Spontaneous Urticaria

PURPOSEOF REVIEW

Chronic spontaneous urticaria and chronic inducible urticaria (CSU/CindU) are caused by mast cell and basophil activation leading to degranulation and the release of histamine and several other mediators. Three kinds of factors can trigger mast cells in CSU: (1) activation of stimulating receptor(s) on the mast cell membrane, (2) upregulation of certain receptor(s), and (3) intracellular dysregulation in signaling with overexpression of the spleen tyrosine kinase (SYK) or reduced activation of the inhibitory Src homology 2 (SH2)-containing inositol phosphatases (SHIP)-related pathways. In CSU, two major endotypes exist based on the primary receptor activating mechanism: type I hypersensitivity (IgE-mediated, directed against auto-allergens) and type IIb (autoimmune, via IgG autoantibodies directed against IgE or the IgE-receptor). Their treatment responses vary. We discuss in vitro and in vivo biomarkers.

RECENT FINDINGS

Patients with auto-allergic CSU have clinical characteristics that can distinguish them partly from those with autoimmune CSU. Most importantly, their disease generally presents a less aggressive course, a better response to second generation (up-dosed) antihistamines and a good response to omalizumab, if necessary. Meanwhile, autoimmune CSU/CindU patients fare less well and often need immunosuppressive drugs. Biomarkers that might help endotype CSU/CindU patients and select the most appropriate treatment, dose, and duration, e.g., for autoallergic CSU, high total IgE and IgE against auto-allergens; for autoimmune CSU, low IgE, basopenia, and IgG against autoantigens like thyroid peroxidase and a positive autologous serum skin test (but sometimes also positive in autoallergy). Some biomarkers are easily accessible but of low specificity; others are highly specific but more futuristic.