Cutaneous inflammatory cell infiltrate in chronic idiopathic urticaria: comparison of patients with and without anti-FcepsilonRI or anti-IgE autoantibodies

Mast cell signaling and its role in urticaria

Chronic urticaria is a mast cell (MC)-driven disease characterized by the development of itching wheals and/or angioedema. In the last decades, outstanding progress has been made in defining the mechanisms involved in MC activation, and novel activating and inhibitory receptors expressed in MC surface were identified and characterized. Besides an IgE-mediated activation through high-affinity IgE receptor cross-linking, other activating receptors, including Mas-related G-protein-coupled receptor-X2, C5a receptor, and protease-activated receptors 1 and 2 are responsible for MC activation. This would partly explain the reason some subgroups of chronic spontaneous urticaria (CSU), the most frequent form of urticaria in the general population, do not respond to IgE target therapies, requiring other therapeutic approaches for improving the management of the disease. In this review, we shed some light on the current knowledge of the immunologic and nonimmunologic mechanisms regulating MC activation in CSU, considering the complex inflammatory scenario underlying CSU pathogenesis, and novel potential MC-targeted therapies, including surface receptors and cytoplasmic signaling proteins.

Chronic Spontaneous Urticaria: Etiology and Pathogenesis

Urticaria, also known as hives, is a common condition thought to affect up to 20% of individuals worldwide in their lifetime. This skin condition is characterized by the appearance of pruritic, erythematous papules or plaques with superficial swelling of the dermis. The major complaint is the symptom of pruritus. Angioedema, which involves a deeper swelling of dermal or mucosal tissues, may accompany urticaria. Urticaria can be classified by both time course of symptoms and the underlying etiology.

Urticarial Vasculitis Differs From Chronic Spontaneous Urticaria in Time to Diagnosis, Clinical Presentation, and Need for Anti-Inflammatory Treatment: An International Prospective UCARE Study

BACKGROUND

Chronic spontaneous urticaria (CSU) and urticarial vasculitis (UV) share several clinical features including the occurrence of wheals. As of yet, the criteria for differentiating the 2 disorders are not clearly defined.

OBJECTIVE

Here, we aimed to identify differences, similarities, and the likelihood for specific clinical features in patients with UV versus those with CSU.

METHODS

Across 10 Urticaria Centers of Reference and Excellence, 106 patients with skin biopsy-confirmed UV and 126 patients with CSU were prospectively recruited to complete a questionnaire on the clinical features, course, and response to treatment of their disease.

RESULTS

As compared with CSU, patients with UV more often experienced postinflammatory skin hyperpigmentation, wheals of ≥24-hour duration, eye inflammation, and fever (6.9, 4.0, 3.6, and 2.4 times, respectively). Clinical features that increased the risk for UV diagnosis when present at the onset of disease included wheals of ≥24-hour duration (7.3-fold), pain of the skin (7.0-fold), postinflammatory hyperpigmentation (4.1-fold), and fatigue (3.1-fold). The diagnostic delay was markedly longer for normocomplementemic UV as compared with hypocomplementemic UV and CSU (21 vs 5 vs 6 months, respectively). Oral corticosteroids and omalizumab were the most effective treatments in patients with UV and CSU, respectively. Patients with UV showed a higher need for immunosuppressive and anti-inflammatory therapies than patients with CSU.

CONCLUSIONS

Long wheal duration, skin pain and hyperpigmentation, and systemic symptoms point to UV rather than CSU as the underlying disease and should prompt further diagnostic workup including a skin biopsy.

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.

Aeroallergens in Atopic Dermatitis and Chronic Urticaria

PURPOSE OF REVIEW

While aeroallergens are a well-established trigger of asthma and allergic rhinitis, their role in allergic skin diseases such as atopic dermatitis and chronic urticaria remains controversial. This paper reviews the pathophysiology and clinical evidence for aeroallergens in these allergic skin diseases and summarizes current strategies for evaluation and management.

RECENT FINDINGS

Current evidence implicates aeroallergens as triggers of cutaneous reactions in atopic dermatitis. Direct skin contact is the likely route of trigger. Aeroallergens may also trigger chronic urticaria, though mechanistic studies are limited. These allergens may cross the skin barrier and directly trigger neurons to release substance P, resulting in mast cell degranulation and dumping of histamine and prostaglandin D2. Many studies link aeroallergen sensitization to chronic urticaria, and case reports suggest the utility of avoidance strategies. The role of aeroallergens as a trigger is clear in atopic dermatitis and becoming emergent in chronic urticaria. Skin prick testing or serum-specific immunoglobulin E testing may be used to determine sensitivities. Management at this time centers on avoidance, and further studies are necessary to evaluate the efficacy of aeroallergen immunotherapy for both conditions.

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

Chronic spontaneous urticaria is characterized by a perivascular non-necrotizing cellular infiltrate around small venules of the skin. It consists primarily of CD4(+) lymphocytes, a prominence of the T helper (Th)2 subtype but also Th1 cells, with Th17 cell-derived cytokines elevated in plasma. There are also neutrophils, eosinophils, basophils, and monocytes. Chemokines derived from mast cells and activated endothelial cells drive the process. Although the role of the cellular infiltrate has not previously been addressed, each constituent can contribute to the overall pathogenesis. It is of interest that CSU responds to corticosteroid, yet, short-term steroids do not affect autoimmunity or degranulation of mast cells, and act on margination of cells along the endothelium and chemotaxis to enter the surrounding dermis. In this review, we address each cell's contribution to the overall inflammatory response, as it is currently understood, with a view toward development of therapeutic options that impede the function of critical cells and/or their secretory products.

Hematologic parameters as biomarkers for antihistamine and omalizumab resistance in chronic spontaneous urticaria

Background: Biomarkers of resistance to H₁-antihistamines (AH) and omalizumab in chronic spontaneous urticaria (CSU) are still a matter of debate. Objective: To identify clinical and laboratory attributes of the patient that may be predictive of AH and omalizumab resistance in CSU. Methods: We conducted a retrospective observational study by using the electronic patient record data base of patients with CSU and of sex- and age-matched controls. Patients with CSU were divided into three study groups: the CSU group, patients who responded to AHs; the antihistamine-resistant CSU (AH-CSU) group, patients refractory to a fourfold AH dose; and the control group, composed of a random sample of age- and sex-matched subjects, with a case-control ratio of 1:2. The patients in the AH-CSU group treated with omalizumab were compared according to the response or resistance to omalizumab. Results: A total of 106 subjects in the AH-CSU group, 483 in the CSU group, and 1198 in the control group were compared. Both AH-CSU (112.7 ± 43.1 kU/mL) and CSU (129.5 ± 52.4 kU/mL) groups were associated with higher plasma total IgE levels than control group (103.2 ± 49.5 kU/mL; p < 0.001). The AH-CSU group was characterized by a higher plasma high-sensitivity C-reactive protein level (6.4 ± 3.7 mg/L) than the CSU group (4.3 ± 1.4 mg/L; p < 0.001) and the control group (3.1 ± 1.8 mg/L; p < 0.001). The AH-CSU and CSU groups were characterized by a lower mean ± standard deviation basophil counts (0.18 ± 0.16 cells ×10⁹/L and 0.19 ± 0.11 cells ×10⁹/L, respectively) than the control group (0.22 ± 0.09 cells ×10⁹/L; p < 0.001). The mean platelet volume was higher in the AH-CSU group (11.2 ± 0.3 fL) than in the CSU group (11.1 ± 0.4 fL; p = 0.002) and in the control group (10.3 ± 0.4 fL; p < 0.001). There were no significant differences in the mean levels of lymphocytes, monocytes, eosinophils, basophils, and platelets, and the rates of eosinopenia and basopenia between the patients in the AH-CSU group who responded to and those who were resistant to omalizumab. Conclusion: This study provided additional data of interest to examine the pathophysiologic role of low-grade inflammation and basopenia in patients with CSU and resistant to AHs and omalizumab.

A novel ELISA method to determine human MrgX2 in chronic urticaria

BACKGROUND

Mas-related G-protein coupled receptor member X2 (MrgX2) directly mediates drug-induced pseudo allergic reactions. Skin mast cell MrgX2 is upregulated in severe chronic urticaria (CU). Mast cells and leukocytes are key effector cells in allergic reactions and undergo degranulation upon stimulation. It is unknown whether circulating MrgX2 expression can be detected occurs in the whole blood of CU patients and reflects pseudo-allergic reaction. There is no effective method for its detection. Therefore, an enzyme-linked immuno-sorbent assay (ELISA) for MrgX2 was developed.

METHODS

Monoclonal and polyclonal MrgX2 specific antibodies were obtained from rabbits and mice immunized by MrgX2 peptides prepared. Indirect ELISA and Dot blot were used to determine antibody titers before a sandwich ELISA for MrgX2 was established. The whole blood from healthy subjects and CU patients was used to detect MrgX2 concentrations. The use of feasibility of this MrgX2-ELISA as a clinical detection tool was explored and diagnostic purposes was assessed.

RESULTS

The sandwich antibody ELISA method for MrgX2 was established with good linearity regression (R² = 0.9910). The lowest detection limit was 3.125 ng/mL. The quantification limit was 6.25 ng/mL. The sandwich ELISA for MrgX2 have good stability and high specificity. The initial truncation value of MrgX2 was 60.91 ng/mL (95% confidence interval). The whole blood MrgX2 concentrations in CU patients (median 98.01 ± 4.317 ng/mL, n = 75) was significantly increased compared to healthy subjects (58.09 ± 1.418 ng/mL, n = 75), with significant difference (p < 0.0001) and higher accuracy of (AUC = 0.8795). Comprehensive the frequency analysis of MrgX2 expression in 75 CU patients reference frequency distribution and ROC curve analysis, determined the threshold for CU patients as 71.23 ng/mL, with 81.33% sensitivity and 90.67% specificity.

CONCLUSION

MrgX2-ELISA provides a useful and convenient method for detecting MrgX2 in whole blood samples. The MrgX2-ELISA will help improve the understanding of the role of MrgX2 in regulating chronic urticaria.

Interleukin 17 receptor A haplotype analysis in chronic spontaneous urticaria: A preliminary study

BACKGROUND

Chronic spontaneous urticaria (CSU) is a distressing skin disease. Family clustering and heterogeneity in the onset and progression indicate that susceptibility to CSU is a complex trait. In this study, we performed haplotype analysis for one of the key player gene, IL17RA, for CSU to test the association with disease susceptibility and severity.

METHODOLOGY

The study included 70 CSU patients and 30 healthy controls. The severity of the disease was evaluated by autologous serum skin test (ASST) and urticaria activity score (UAS). ASST test was done and quality of life was assessed using a questionnaire. Allelic discrimination analysis for rs4819554 and rs879577 was performed using real-time polymerase chain reaction technology.

RESULTS

Carriers of rs4819554*G were more prone to develop CSU than its counterpart (P = .039), while rs4819554*A allele displayed more severe phenotype in the form of more prolonged disease duration (P = .040), concurrent angioedema (P < .001), higher level of treatment (P < .001), and higher score of quality of life (P < .001). Additionally, homozygote patients with rs879577*CC were associated with angioedema (P < .001). Haplotype analysis revealed that cohorts with both rs4819554*A and rs879577*T conferred protection against developing CSU (OR = 0.07, 95% CI = 0.01-0.32, P = .001).

CONCLUSION

Our results showed that IL17RA gene polymorphisms might contribute to the increased susceptibility to CSU.

Angioedema in a Patient with Autoimmune Thyroiditis – A Case Report

We present a case of a 29-year-old Bulgarian woman with autoimmune thyroiditis and recurrent angioedema. The patient presented with a one-year-long history of recurrent angioedema and Hashimoto’s thyroiditis. Physical examination showed oedema surrounded by erythema on the forearms, and erythematous, itchy plaques spreading over her face, neck, chest, abdomen, and extremities. Blood tests showed elevated total immunoglobulin E (IgE). The patient had been diagnosed with Hashimoto’s thyroiditis and hypothyroidism. She had been taking levothyroxine 50 μg/d, resulting in a good hormonal control; however, her anti-thyroid peroxidase (anti-TPO) antibodies were high. She was started on methylprednisolone and antihistamines. In three weeks, we observed a good therapeutic response to the treatment and the lesions remitted. IgE dropped within normal range. Levels of anti-TPO antibodies were persistently high. In conclusion, patients with angioedema should be tested for thyroid autoimmunity. Further delve into the pathogenesis of angioedema in them is warranted in order to explore the possibility of an underlying atopy in those not responding to the standard treatment with levothyroxine.

Eosinopenia, in Chronic Spontaneous Urticaria, Is Associated with High Disease Activity, Autoimmunity, and Poor Response to Treatment

BACKGROUND

Chronic spontaneous urticaria (CSU) is characterized by the degranulation of skin mast cells and the influx of basophils and eosinophils to affected skin sites. Blood basopenia has been linked to severe antihistamine-resistant CSU and type IIb autoimmunity, whereas the role of eosinophils in CSU is largely unknown.

OBJECTIVE

To analyze data from 1613 patients with CSU from 2 centers to study the prevalence, role, and relevance of eosinopenia in CSU.

METHODS

Peripheral blood eosinophil and basophil counts were measured by automated hematology analyzers. Patient files were screened for clinical characteristics, results of laboratory tests, the autologous serum skin test, the serum-induced basophil histamine release assay, and response to second-generation H₁-antihistamines and omalizumab.

RESULTS

Ten percent of patients with CSU had eosinopenia. Eosinopenia was associated with the female sex, high disease activity, autologous serum skin test and basophil histamine release assay positivity, low total IgE, and high levels of C-reactive protein and IgG-antithyroperoxidase (P ≤ .007). Nonresponders to second-generation H₁-antihistamines or omalizumab had significantly lower eosinophils as compared with responders (P < .05 and P < .01, respectively). Blood eosinophil counts correlated with basophil counts (r = 0.396; P < .001), and 81% of patients with CSU with undetectable eosinophils had basopenia. The combination of eosinopenia and basopenia is a better predictor of nonresponse to second-generation H₁-antihistamines than eosinopenia alone (odds ratio of 9.5 vs 4.8).

CONCLUSIONS

Eosinopenia in patients with CSU is associated with type IIb autoimmunity, high disease activity, and poor response to treatment. Eosinophils should be explored as biomarkers and investigated for their contribution to the pathogenesis of CSU.

[What is neutrophilic urticaria?]

Some debate continues to surround the existence of neutrophilic urticaria (NU) as a nosological entity. Certain authors consider NU as a banal form of urticaria since an infiltrate predominantly made up of polynuclear neutrophils (PNN) is seen in certain cases of chronic and acute urticaria. Moreover, it has been stated that the histological appearance of chronic urticaria varies according to the time between appearance of the plaque and the performance of biopsy: the presence of PNN may occur later. According to the literature, there appear to be no specific clinical characteristics associated with the presence of PNN at histology. Most cases exhibit moderate laboratory inflammatory syndrome. Data concerning therapeutic response are contradictory: some studies have shown no significant difference in terms of therapeutic response in relation to banal urticaria, while only one study has demonstrated superior response to dapsone in the case of histologically demonstrated neutrophilic infiltrate. There does not appear to be any disease more frequently associated in the event of NU. In conclusion, the available data concerning NU are insufficient to confirm the existence of this condition. A prospective study comparing routine acute and chronic urticaria biopsies would be extremely useful to better characterise the relationships between cellular infiltrate and therapeutic response.

Human eosinophils and mast cells: Birds of a feather flock together

While the origin of the phrase "birds of a feather flock together" is unclear, it has been in use for centuries and is typically employed to describe the phenomenon that people with similar tastes or interests tend to seek each other out and congregate together. In this review, we have co-opted this phrase to compare innate immune cells of related origin, the eosinophil and mast cell, because they very often accumulate together in tissue sites under both homeostatic and inflammatory conditions. To highlight overlapping yet distinct features, their hematopoietic development, cell surface phenotype, mediator release profiles and roles in diseases have been compared and contrasted. What emerges is a sense that these two cell types often interact with each other and their tissue environment to provide synergistic contributions to a variety of normal and pathologic immune responses.

Omalizumab normalizes the gene expression signature of lesional skin in patients with chronic spontaneous urticaria: A randomized, double-blind, placebo-controlled study

BACKGROUND

Omalizumab, a humanized recombinant monoclonal anti-IgE antibody, proved to be effective in patients with chronic spontaneous urticaria (CSU), including severe and treatment-refractory CSU. Here, we report omalizumab's effect on gene expression in skin biopsies from CSU patients enrolled in a double-blind, placebo-controlled study.

METHODS

Chronic spontaneous urticaria patients (18-75 years) were randomized to either 300 mg omalizumab (n = 20) or placebo (n = 10) administered s.c. every 4 weeks for 12 weeks (NCT01599637). Lesional and nonlesional skin biopsies were collected from the same area of consenting patients and assessed at baseline and on Day 85 compared with skin biopsies from the same area of 10 untreated healthy volunteers (HVs). Gene expression data were generated using Affymetrix HG-U133Plus2.0 microarrays. Statistical analyses were performed using R packages.

RESULTS

At baseline, 63 transcripts were differentially expressed between lesional and nonlesional skin. Two-thirds of these lesional signatures were also differentially expressed between lesional and HV skin. Upon treatment with omalizumab, >75% of lesional signatures changed to reflect nonlesional skin expression levels (different vs placebo, P < 0.01). Transcripts upregulated in lesional skin (vs nonlesional and/or HV skin) suggested increased mast cell/leukocyte infiltration (FCER1G, C3AR1, CD93, S100A8, and S100A9), increased oxidative stress, vascularization (CYR61), and skin repair events (KRT6A, KRT16). Lesional signatures were not modulated by treatment in nonresponders (defined based on UAS7 longitudinal changes ≥16).

CONCLUSION

Omalizumab, in treatment responders, reverted transcriptional signatures associated with CSU lesion phenotype to reflect nonlesional/HV expression levels; this is consistent with observed omalizumab-mediated clinical improvement observed in patients with CSU.

The overlap syndrome of urticaria and gastroesophageal reflux disease

BACKGROUND

One-quarter of systemic symptoms associated with chronic spontaneous urticaria (CSU) are related to gastrointestinal complaints (GICs).

OBJECTIVES

To investigate the prevalence and features of urticaria-overlapping GICs.

METHODS

In this retrospective cross-sectional survey, 1426 consecutive outpatients were observed at our University Department. Only patients suffering from urticaria or GICs with a complete diagnostic work-up including serum total IgE level (Tot-IgE), differential blood count and urticaria activity score (UAS), were evaluated.

RESULTS

Among different GICs, gastroesophageal reflux disease (GERD) was the most frequent syndrome observed (15.4%; 95%CI: 13.6-17.3). The prevalence of overlap syndrome for urticaria and GERD was 5.9% (95%CI: 4.7-7.2). In urticaria-patients, the prevalence of GERD was four-fold higher than in patients without hives (44% vs. 11%, p<0.001). UAS was significantly higher in urticaria and GERD overlap syndromes vs. isolated urticarias. In patients with GERD or acute/chronic urticaria or overlap syndrome, Tot-IgE and eosinophil blood count (EBC) differed significantly, with a stepwise increase in their values; from the subgroup of patients with GERD only, to that with overlap of CSU to GERD. Prevalence values for urticaria overlapping with GERD were three- and two-fold higher in CSU and in long-duration GERD cases respectively compared to acute urticaria or short-duration GERD cases. Similar to Th2 pathology models, CSU and GERD overlap syndrome was significantly and independently associated with Total-IgE ≥100IU/ml or EBC ≥250/mmc compared to CSU or GERD. Endoscopic/bioptic findings of non-erosive reflux disease (NERD) or Barrett's esophagus (BE) were more frequent in chronic overlap syndrome than in GERD-patients.

CONCLUSIONS

GERD was the most frequent GIC in patients with urticaria. Overlap syndrome was more frequent among patients with CSU, where this syndrome was associated with higher values of UAS, Tot-IgE, EBC and frequencies of NERD and BE. These results suggest that overlap syndrome is frequently a chronic syndrome with a Th2-like profile.

Chronic Spontaneous Urticaria: The Devil's Itch

Chronic urticaria is defined as the presence of urticaria for a period exceeding 6 weeks, assuming symptoms for most days of the week. It is divided into chronic inducible urticarias and chronic spontaneous urticaria, previously termed chronic idiopathic urticaria. The latter designation emphasizes that patients can experience urticaria independent of any exogenous stimulus even if one can define circumstances that may worsen symptoms. A search for such an external "cause" is fruitless because the underlying abnormality is "intrinsic," whether it is autoimmune, or some unknown process. Approximately 40% of patients with chronic spontaneous urticaria report accompanying episodes of angioedema, whereas 10% have angioedema as their primary manifestation. In most cases, it is a self-limiting disorder, persisting for 2 to 5 years in most cases, although 20% of patients suffer for more than 5 years. The treatment that has evolved is largely empiric, based on double-blind, placebo-controlled studies whenever possible, but is not yet targeted to any particular pathogenic mechanism. In this article, we review the current status regarding pathogenesis, discuss the diagnostic workup, and update the approach to treatment including consideration of published guidelines, our own experience, and guideline updates that are being prepared.

The Histopathology of Urticaria Revisited-Clinical Pathological Study

BACKGROUND

The classic histopathological findings of urticaria include dermal edema and a sparse perivascular infiltrate of neutrophils, eosinophils, macrophages, and lymphocytes. However, this pattern is inconsistently described.

OBJECTIVE

To describe the histological and immunofluorescence characteristics of urticaria and to identify distinctive patterns.

METHODS

A retrospective study was performed in which the medical files and biopsy specimens of 58 patients with acute and chronic classical urticaria were reviewed. Pathological parameters were quantified.

RESULTS

We recognized 2 distinctive patterns of urticaria: lymphocyte and neutrophil predominant; the former was characterized by a perivascular location, whereas the latter was associated with an interstitial location and a denser infiltrate. Mast cells were relatively sparse, better demonstrated with special stains. Tryptase stain demonstrated more mast cells than Giemsa stain. Extravasated erythrocytes were present in 50% of the cases, but vasculitis was not observed.

CONCLUSIONS

Histological findings in classical urticaria show a spectrum of findings from a sparse superficial perivascular to a deep perivascular and interstitial infiltrate. Distinctive groups based on the dominant cell type can be identified, accounting for the similarity to neutrophilic urticarial dermatosis. Lesions may have a purpuric appearance, but leukocytoclastic vasculitis is never present.

Mediators of Inflammation and Angiogenesis in Chronic Spontaneous Urticaria: Are They Potential Biomarkers of the Disease?

In chronic spontaneous urticaria (CSU), different pathophysiological mechanisms, potentially responsible for the development of the disease, have been recently described. It is likely that the activation of skin mast cells with consequent release of histamine and other proinflammatory mediators is responsible for vasodilation in the lesional skin of CSU. However, the underlying causes of mast cell activation in the disease are largely unknown and remain to be identified. Thus, in this review, we discuss new insights in the pathogenesis of CSU, focusing on inflammation and angiogenesis. The understanding of these mechanisms will enable the identification of biomarkers useful for the diagnosis, follow-up, and management of CSU and will allow the development of novel, more specific, and patient-tailored therapies.

Mechanisms of action that contribute to efficacy of omalizumab in chronic spontaneous urticaria

The monoclonal anti-immunoglobulin E (IgE) antibody, omalizumab, was the first drug approved for use in patients with chronic idiopathic/spontaneous urticaria (CIU/CSU) who remain symptomatic despite H₁ -antihistamine treatment. Omalizumab binds to free IgE, which lowers free IgE levels and causes FcεRI receptors on basophils and mast cells to be downregulated. It has been shown to improve symptoms of CIU/CSU, but its mechanism of action is not currently understood. Potential mechanisms in CIU/CSU include reducing mast cell releasability, reversing basopenia and improving basophil IgE receptor function, reducing activity of IgG autoantibodies against FcεRI and IgE, reducing activity of IgE autoantibodies against an antigen or autoantigen that has yet to be definitively identified, reducing the activity of intrinsically 'abnormal' IgE, and decreasing in vitro coagulation abnormalities associated with disease activity. However, none of these theories alone or in combination fully account for the pattern of symptom improvement seen with omalizumab therapy, and therefore, no one mechanism is likely to be the definitive mechanism of action. Additional research is needed to further clarify the involvement of omalizumab in relieving symptoms associated with the complex, multifactorial pathogenesis of CIU/CSU.

Clinical efficacy of omalizumab in chronic spontaneous urticaria is associated with a reduction of FcεRI-positive cells in the skin

Background. Treatment with omalizumab, a humanized recombinant monoclonal anti-IgE antibody, results in clinical efficacy in patients with Chronic Spontaneous Urticaria (CSU). The mechanism of action of omalizumab in CSU has not been elucidated in detail. Objectives. To determine the effects of omalizumab on levels of high affinity IgE receptor-positive (FcεRI⁺) and IgE-positive (IgE⁺) dermal cells and blood basophils. Treatment efficacy and safety were also assessed. Study design. In a double-blind study, CSU patients aged 18‑75 years were randomized to receive 300 mg omalizumab (n=20) or placebo (n=10) subcutaneously every 4 weeks for 12 weeks. Changes in disease activity were assessed by use of the weekly Urticaria Activity Score (UAS7). Circulating IgE levels, basophil numbers and levels of expression of FcεRI⁺ and IgE⁺ cells in the skin and in blood basophils were determined. Results. Patients receiving omalizumab showed a significantly greater decrease in UAS7 compared with patients receiving placebo. At Week 12 the mean difference in UAS7 between treatment groups was -14.82 (p=0.0027), consistent with previous studies. Total IgE levels in serum were increased after omalizumab treatment and remained elevated up to Week 12. Free IgE levels decreased after omalizumab treatment. Mean levels of FcεRI⁺ skin cells in patients treated with omalizumab 300 mg were decreased at Week 12 compared with baseline in the dermis of both non-lesional and lesional skin, reaching levels comparable with those seen in healthy volunteers (HVs). There were no statistically significant changes in mean FcɛRI⁺ cell levels in the placebo group. Similar results were seen for changes in IgE⁺ cells, although the changes were not statistically significant. The level of peripheral blood basophils increased immediately after treatment start and returned to Baseline values after the follow-up period. The levels of FcεRI and IgE expression on peripheral blood basophils were rapidly reduced by omalizumab treatment up to Week 12. Conclusions. Treatment with omalizumab resulted in rapid clinical benefits in patients with CSU. Treatment with omalizumab was associated with reduction in FcɛRI⁺ and IgE⁺ basophils and intradermal cells.

Roles of Mas-related G protein-coupled receptor X2 on mast cell-mediated host defense, pseudoallergic drug reactions, and chronic inflammatory diseases

Mast cells (MCs), which are granulated tissue-resident cells of hematopoietic lineage, contribute to vascular homeostasis, innate/adaptive immunity, and wound healing. However, MCs are best known for their roles in allergic and inflammatory diseases, such as anaphylaxis, food allergy, rhinitis, itch, urticaria, atopic dermatitis, and asthma. In addition to the high-affinity IgE receptor (FcεRI), MCs express numerous G protein-coupled receptors (GPCRs), which are the largest group of membrane receptor proteins and the most common targets of drug therapy. Antimicrobial host defense peptides, neuropeptides, major basic protein, eosinophil peroxidase, and many US Food and Drug Administration-approved peptidergic drugs activate human MCs through a novel GPCR known as Mas-related G protein-coupled receptor X2 (MRGPRX2; formerly known as MrgX2). Unique features of MRGPRX2 that distinguish it from other GPCRs include their presence both on the plasma membrane and intracellular sites and their selective expression in MCs. In this article we review the possible roles of MRGPRX2 on host defense, drug-induced anaphylactoid reactions, neurogenic inflammation, pain, itch, and chronic inflammatory diseases, such as urticaria and asthma. We propose that host defense peptides that kill microbes directly and activate MCs through MRGPRX2 could serve as novel GPCR targets to modulate host defense against microbial infection. Furthermore, mAbs or small-molecule inhibitors of MRGPRX2 could be developed for the treatment of MC-dependent allergic and inflammatory disorders.

Economic burden of refractory chronic spontaneous urticaria on Kuwait's health system

Background

Chronic spontaneous urticaria (CSU) is a common problem worldwide. We evaluated the direct medical costs of treating patients with refractory CSU and the budget effect of omalizumab use in these patients in Kuwait.

Methods

The prevalence of CSU was estimated using the Delphi method. Medical records of patients with refractory CSU in Kuwait were reviewed. Costs were calculated from a health system perspective. One-way sensitivity analyses were conducted on the price and utilization of each cost component.

Results

Before omalizumab use, the total direct costs of treating 1,293 patients with refractory CSU were estimated to be USD 3,650,733 per year. This estimation was principally generated by outpatient visits. After omalizumab use, the cost was sensitive to price variation and estimated to be USD 15,828,612 per year. All other direct costs were reduced.

Conclusion

The economic burden of refractory CSU in Kuwait is high. Omalizumab use is costly, but its administration reduces all other direct costs.

An individualized diagnostic approach based on guidelines for chronic urticaria (CU)

Chronic urticaria (CU), defined as the spontaneous or inducible appearance of hives, angioedema or both for 6 weeks or more, presents with a number of subtypes which all substantially impair patients' quality of life (QoL). International urticaria guidelines give clear recommendations on workup and treatment but the occurrence of CU with multiple causes and triggers (sometimes with more than one subtype occurring in a single patient) presents challenges for an individualized assessment by physicians. This review summarizes recent guidance on the classification, diagnosis and assessment of CU subtypes and discusses how currently available patient assessment tools and laboratory tests can be used in clinical practice as part of an individualized patient management plan.

Identification of a Th2- and Th17-skewed immune phenotype in chronic urticaria with Th22 reduction dependent on autoimmunity and thyroid disease markers

BACKGROUND

Chronic urticaria is a condition with many inciting factors and often presents a therapeutic challenge to clinicians. In addition to a central role for mast cells, an immune dysregulated state related to cytokine/chemokine alterations is increasingly being recognized.

METHODS

Biopsies of chronic urticaria (n = 11) and normal skin (n = 5) were evaluated with immunostains for CD117, CD3 and dual stains for CD4/T-bet, GATA-3, STAT-3 or BNC-2 (transcription factors specific and mutually exclusive for Th1, Th2, Th17 and Th22 cells, respectively). Clinical data, including autoantibodies and thyroid function tests, and the number of CD117+ mast cells and percent of Th1, Th2, Th17 and Th22 of CD3+ T-cells were compared.

RESULTS

Th2 cells and Th17 cells were significantly more frequent in chronic urticaria than controls. In contrast, there was no significant difference in mast cells, Th1 cells or Th22 cells. Three of nine chronic urticaria patients had evidence of autoimmune disease; biopsies from these patients trended toward a greater number of mast cells and decreased percent of Th-cell subtypes as compared with those without autoimmunity markers, with significantly less Th22 cells.

CONCLUSIONS

These findings provide novel insight into the role of Th2 and Th17 in chronic urticaria pathophysiology and may impact therapy.

Calcitonin gene-related peptide and vascular endothelial growth factor are expressed in lesional but not uninvolved skin in chronic spontaneous urticaria

BACKGROUND

The mechanisms for producing weals in chronic spontaneous (idiopathic) urticaria (CSU) are incompletely understood. Leucocyte infiltration with vascular leakage and expression of the potent vasoactive agents' calcitonin gene-related peptide (CGRP) and vascular endothelial growth factor (VEGF) are features of late-phase allergic skin reactions, previously proposed as a model of CSU.

OBJECTIVE

To measure CGRP and VEGF expression in lesional and non-lesional skin from CSU patients and to compare results with a control group.

METHODS

Eight paired biopsies (one from 4-8 h spontaneous weals and one from uninvolved skin) were taken from eight patients with CSU and nine control subjects and studied by immunohistochemistry and confocal microscopy.

RESULTS

Lesional skin in CSU contained significantly more CGRP+ and VEGF+ cells than non-lesional skin. No significant differences were observed in CGRP and VEGF expression between non-lesional skin and controls. In lesional skin, VEGF and CGRP co-localised to UEA-1+ blood vessels. CGRP was also expressed by neutrophils and eosinophils and to a lesser extent by CD90(+) fibroblasts, mast cells, CD3(+) and CD68(+) cells. CGRP and VEGF expression was not related to the duration of disease.

CONCLUSION AND CLINICAL RELEVANCE

Increased expression of CGRP and VEGF in lesional, but not uninvolved, skin indicates that these potent vasoactive agents may play a role in wealing and tissue oedema in CSU so representing novel targets in therapy.

Chronic urticaria: new management options

Chronic urticaria is defined as episodic or daily hives lasting for at least 6 weeks and impairs quality of life. Two main subtypes include chronic idiopathic (spontaneous) urticaria and inducible (physical) urticaria, but some patients have urticarial vasculitis. “Autoimmune chronic urticaria” implies the presence of histamine releasing or mast cell activating autoantibodies to IgE or FcϵRI, the high affinity receptor on mast cells and basophils. In patients not readily controlled with labeled dosages of second generation H₁ receptor antagonists (antihistamines), there is evidence for reduction of urticaria using up to 4 fold increases in labeled dosages. The biologic modifier, omalizumab, helps to reduce lesions of chronic urticaria within 1–2 weeks.

Elevations in vascular markers and eosinophils in chronic spontaneous urticarial weals with low-level persistence in uninvolved skin

BACKGROUND

In chronic spontaneous urticaria (CSU) mast cell activation together with inflammatory changes in the skin are well documented and may play an important role in mechanisms of tissue oedema.

OBJECTIVES

To confirm and extend these observations by measuring microvascular markers, leucocytes and mast cell numbers in lesional and uninvolved skin and to compare findings with a control group.

METHODS

Paired biopsies (one from 4-8-h spontaneous weals and one from uninvolved skin) were taken from eight patients with CSU and nine control subjects and studied using immunohistochemistry and confocal microscopy using the lectin Ulex europaeus agglutinin 1 (UEA-1).

RESULTS

Lesional skin in CSU contained significantly more CD31+ endothelial cells; CD31+ blood vessels, neutrophils, eosinophils, basophils and macrophages; and CD3+ T cells than nonlesional skin. Increased vascularity was confirmed by confocal imaging using the lectin UEA-1. Uninvolved skin from CSU contained significantly more CD31+ endothelial cells, CD31+ blood vessels and eosinophils compared with the control subjects. There was a threefold increase in mast cell numbers when CSU was compared with controls but no difference was observed between lesional and uninvolved skin.

CONCLUSIONS

Increased vascular markers together with eosinophil and neutrophil infiltration are features of lesional skin in CSU and might contribute to tissue oedema. Eosinophils and microvascular changes persist in uninvolved skin, which, together with increased mast cells, suggests that nonlesional skin is primed for further wealing.

Expression of Mas-related gene X2 on mast cells is upregulated in the skin of patients with severe chronic urticaria

BACKGROUND

Wheal reactions to intradermally injected neuropeptides, such as substance P (SP) and vasoactive intestinal peptide, are significantly larger and longer lasting in patients with chronic urticaria (CU) than in nonatopic control (NC) subjects. Mas-related gene X2 (MrgX2) has been identified as a receptor for basic neuropeptides, such as SP and vasoactive intestinal peptide. Mast cell (MC) responsiveness to eosinophil mediators contributes to the late-phase reaction of allergy.

OBJECTIVE

We sought to compare the frequency of MrgX2 expression in skin MCs from patients with CU and NC subjects and to identify the receptor for basic eosinophil granule proteins on human skin MCs.

METHODS

MrgX2 expression was investigated by using immunofluorescence in skin tissues from NC subjects and patients with severe CU and on skin-derived cultured MCs. MrgX2 expression in human MCs was reduced by using a lentiviral small hairpin RNA silencing technique. Ca(2+) influx was measured in CHO cells transfected with MrgX2 in response to eosinophil granule proteins. Histamine and prostaglandin D2 levels were measured by using enzyme immunoassays.

RESULTS

The number of MrgX2(+) skin MCs and the percentage of MrgX2(+) MCs in all MCs in patients with CU were significantly greater than those in NC subjects. Eosinophil infiltration in urticarial lesions was observed in 7 of 9 patients with CU. SP, major basic protein, and eosinophil peroxidase, but not eosinophil-derived neurotoxin, induced histamine release from human skin MCs through MrgX2.

CONCLUSION

MrgX2 might be a new target molecule for the treatment of wheal reactions in patients with severe CU.

Therapy of chronic urticaria: a simple, modern approach

OBJECTIVE

To examine the available treatment choices for chronic spontaneous urticaria (CSU) and discuss a new paradigm for treating such patients.

DATA SOURCES

The literature regarding treatment is reviewed, including considerations of published guidelines. Attention is focused on the most recent evidence indicating particular efficacy of omalizumab.

RESULTS

Omalizumab has been found to have considerable efficacy in phase 2 and phase 3 trials in which more than 900 patients have been studied. A response rate of 65% is seen in patients resistant to antihistamines as well as to histamine2 blockers and leukotriene antagonists, and 40% of patients are completely free of hives as long as therapy is continued. In addition, serious adverse events have not been seen. Only cyclosporine can match this response rate (excluding steroids), but the adverse effect profile (blood pressure and renal function) is substantial by comparison. Double-blind, placebo-controlled studies of other agents often listed as alternatives are lacking (ie, whether their success rate exceeds the 25%-30% placebo response is uncertain). The mechanism by which omalizumab works in CSU is not clear because the response rate is unrelated to the autoimmune profile and can occur rapidly (ie, within a few days).

CONCLUSION

Omalizumab has exceptional efficacy for antihistamine-resistant CSU with an excellent adverse effect profile.

Chronic spontaneous urticaria: etiology and pathogenesis

Urticaria affects individuals of all ages and is commonplace. Nearly 1 in 5 individuals will experience an episode of urticaria in their lifetime, while the chronic form of disease has an estimated annual prevalence of approximately 1% of the population. Given the similarity of chronic urticaria symptoms to those seen in patients suffering an allergic reaction, the condition often leads to a search for an external cause. In most cases, no external trigger factor is identified. At present several theories of pathogenesis exist, none of which is firmly established.

The unusual association of Graves' disease, chronic spontaneous urticaria, and premature ovarian failure: report of a case and HLA haplotype characterization

Chronic spontaneous urticaria (CSU), defined as the occurrence of spontaneous wheals for more than six weeks, has been associated with autoimmune diseases. Herein, we report the unusual association of CSU, Graves' disease, and premature ovarian failure. Human leukocyte antigen (HLA) studies were performed. A 36-year-old woman presented symptoms and signs of hyperthyroidism for three months. In the same period, the patient complained of widespread urticarial wheals, intensely itchy, and poorly responsive to therapy with antihistaminic agents. Hyperthyroidism was confirmed biochemically, and treatment with methimazole was started. As hyperthyroidism improved, a marked improvement in her urticaria was also observed. However, the patient continued to complain of amenorrhea. Endocrine evaluation, at the age 38, was consistent with premature ovarian failure. This is the first report of coexistence of GD, CSU, and POF. The genetic background of such unusual association is a specific combination of HLA.

Biologic agents in the treatment of urticaria

Numerous controlled studies as well as case reports have demonstrated that Omalizumab can be employed successfully in approximately 75 % of patients with chronic spontaneous urticaria, leading to a dramatic decrement in symptoms with very few side effects. No other drug currently available is comparable, and the success rate in patients resistant to antihistamines is no different. In the U.S., Phase I and Phase II trials are complete and we await the results of a Phase III multicenter study, with a view to eventual submission to the Food and Drug Administration in the U.S. and to comparable agencies abroad seeking approval for this indication. Omalizumab is currently marketed for the treatment of severe allergic asthma. Case reports suggest efficacy in difficult cases of physical urticaria, but no controlled trails have been done. Other agents require further evaluation for possible efficacy in the treatment of chronic spontaneous urticaria, including antibody to CD20, a B-lymphocyte cell surface marker, anti-TNFα, and anti-Interleukin 1. Thus far, targeting TNFα has been disappointing for this indication, while targeting Interleukin I has dramatically ameliorated autoinflammatory disorders with urticaria or urticaria-vasculitic-like lesions such as cold-induced autoinflammatory syndrome, Muckle-Wells syndrome, and Schnitzler syndrome.

Angioedema

Angioedema can be caused by either mast cell degranulation or activation of the kallikrein-kinin cascade. In the former case, angioedema can be caused by allergic reactions caused by immunoglobulin E (IgE)-mediated hypersensitivity to foods or drugs that can also result in acute urticaria or a more generalized anaphylactic reaction. Nonsteroidal anti-inflammatory drugs (cyclooxygenase 1 inhibitors, in particular) may cause angioedema with or without urticaria, and leukotrienes may have a particular role as a mediator of the swelling. Reactions to contrast agents resemble allergy with basophil and mast cell degranulation in the absence of specific IgE antibody and can be generalized, that is, anaphylactoid. Angioedema accompanies chronic urticaria in 40% of patients, and approximately half have an autoimmune mechanism in which there is IgG antibody directed to the subunit of the IgE receptor (40%) or to IgE itself (5%-10%). Bradykinin is the mediator of angioedema in hereditary angioedema types I and II (C1 inhibitor [INH] deficiency) and the newly described type III disorder some of which are caused bya mutation involving factor XII. Acquired C1 INH deficiency presents in a similar fashion to the hereditary disorder and is due either toC1 INH depletion by circulating immune complexes or to an IgG antibody directed to C1 INH. Although each of these causes excessive bradykinin formation because of activation of the plasma bradykinin-forming pathway, the angioedema due to angiotensin-converting enzyme inhibitors is caused by excessive bradykinin levels due to inhibition of bradykinin degradation. Idiopathic angioedema (ie, pathogenesis unknown) may be histaminergic, that is, caused by mast cell degranulation with histamine release, or nonhistaminergic. The mediator pathways in the latter case are yet to be defined. A minority may be associated with the same autoantibodies associated with chronic urticaria. Angioedema that is likely to be life threatening (laryngeal edema or tongue/pharyngeal edema that obstructs the airway) is seen in anaphylactic/anaphylactoid reactions and the disorders mediated by bradykinin.

Eosinophils in chronic urticaria: supporting or leading actors?

Although their number may be increased in skin lesions, eosinophils have been rather neglected as possible participants to the pathogenesis of chronic urticaria because of the absence of peripheral eosinophilia in patients with this disease. However, recent data suggest a potentially relevant role played by activated eosinophils both in triggering the tissue factor pathway of coagulation cascade and as a source of vascular endothelial growth factor. Such phenomena seem more pronounced in patients showing a more severe disease. The present study will rediscuss the potential role of this cell line in chronic urticaria in the light of these recent observations.

Diagnosis and treatment of urticaria and angioedema: a worldwide perspective

: Urticaria and angioedema are common clinical conditions representing a major concern for physicians and patients alike. The World Allergy Organization (WAO), recognizing the importance of these diseases, has contributed to previous guidelines for the diagnosis and management of urticaria. The Scientific and Clinical Issues Council of WAO proposed the development of this global Position Paper to further enhance the clinical management of these disorders through the participation of renowned experts from all WAO regions of the world. Sections on definition and classification, prevalence, etiology and pathogenesis, diagnosis, treatment, and prognosis are based on the best scientific evidence presently available. Additional sections devoted to urticaria and angioedema in children and pregnant women, quality of life and patient-reported outcomes, and physical urticarias have been incorporated into this document. It is expected that this article will supplement recent international guidelines with the contribution of an expert panel designated by the WAO, increasing awareness of the importance of urticaria and angioedema in medical practice and will become a useful source of information for optimum patient management worldwide.

Clinical evaluation of the computerized chronic urticaria-specific quality of life questionnaire in Korean patients with chronic urticaria

BACKGROUND

Chronic urticaria (CU) is a common skin disorder that affects the well-being and quality of life (QOL) of patients. Recently, we developed and validated a questionnaire for measuring QOL in Korean patients with CU, called the Chronic Urticaria-Specific Quality of Life (CU-QOL) questionnaire.

AIM

To evaluate the clinical significance of a computerized version of the CU-QOL, in adult patients with CU.

METHODS

This was a cross-sectional observational study that enrolled 249 Korean patients with CU from five university hospitals and measured computerized CU-QOL scores and Urticaria Activity Score (UAS) simultaneously. The internal consistency of the computerized CU-QOL was analysed using Cronbach α. To identify clinical correlations between the CU-QOL and patient characteristics, the atopic status and serum autoantibodies, including antinuclear, antithyroglobulin and antimicrosome antibodies, were measured. Multiple linear regression models were used to identify CU-QOL predictors.

RESULTS

Cronbach α was 0.94 for the overall computerized CU-QOL score. The CU-QOL scores correlated significantly with the UAS (r= -0.49, P<0.001). Of the factors aggravating CU, delayed pressure, sunlight exposure and emotional stress significantly influenced the overall CU-QOL scores in the univariate analysis. Multivariate regression models indicated that UAS and emotional stress were significant predictors of the four domains and of the total CU-QOL scores.

CONCLUSIONS

The computerized CU-QOL is a convenient and valid tool for measuring QOL in patients with CU. This study suggests that UAS, dermatographism and emotional stress are strong CU-QOL predictors in Korean patients with CU.

Treatment of chronic spontaneous urticaria

Chronic spontaneous urticaria is defined as persistent symptoms of urticaria for 6 weeks or more. It is associated with autoimmunity in approximately 45 percent of patients. Therapy is often difficult however the initial approach should employ high-dose non-sedating antihistamines; 4-6 tablets/day may be necessary. It has been shown that the response to 4 tablets/day exceeds 3, and exceeds 2, which exceeds 1. However the dose that corresponds to the maximal dose of first generation antihistamines (hydroxyzine, diphenhydramine) used previously, is 6/day. Yet over half the patients are refractory to antihistamines and other agents should be tried next. Whereas current guidelines (published) often add leukotriene antagonists and/or H₂ receptor antogonists next, these are of little utility. Likewise drugs effective for urticarial vasculitis (colchicine, dapsone, sulfasalazine, hydroxychloroquine) are effective in a small percentage of patients and no study suggests that the response rate of any of them exceeds the 30% placebo responses seen in most double-blind, placebo controlled studies. The drugs that are effective for antihistamine-resistant chronic spontaneous urticaria are corticosteroids, cyclosporine, and Omalizumab. Use of steroids is limited by toxicity. If used at all, a dose of no more than 10 mg/day should be employed with a weekly reduction of 1 mg. The response rates to cyclosporine and Omalizumab are each close to 75%. Cyclosporine can be used effectively if care is taken to monitor blood pressure, urine protein, blood urea nitrogen, and creatinine, every 6 weeks. Omalizumab has the best profile in terms of efficacy/toxicity and, once approved by federal agencies for use in chronic spontaneous urticaria, a dramatic change in the treatment paradigm, whether associated with autoimmunity or not, is predicted. A phase 3 trial is currently in place. Refractoriness to both Omalizumab and cyclosporine is expected to be less than 5 percent of patients. Other agents, can then be tried.

[Neutrophilic urticaria or urticaria with predominantly neutrophilic inflammatory infiltrate: study of its clinical and histopathologic characteristics and its possible association with rheumatic disease]

INTRODUCTION

Neutrophilic urticaria, described by Winkelmann in 1985, has yet to be completely defined and its clinical significance is poorly understood. Nevertheless, recent publications suggest that it could be a marker for rheumatic disease. The primary objective of this study was to compare the prevalence of rheumatic disease in 2 groups of patients with urticaria: those with conventional urticaria (non-neutrophilic inflammatory infiltrate) and those with neutrophilic urticaria.

MATERIAL AND METHODS

We retrospectively reviewed all biopsy samples taken from urticarial lesions in our hospital between January 1, 1999 and June 28, 2009. Urticaria was classified according to predefined morphologic and histopathologic patterns. We compared the clinical and histologic characteristics of neutrophilic urticaria with those of conventional urticarias in the 84 patients included.

RESULTS

Of the 84 patients, 57.1% had neutrophilic urticaria. We did not find significant differences between the percentages of patients with rheumatic disease between the neutrophilic and nonneutrophilic urticaria groups. In patients with acute urticaria, we found a significantly higher proportion of samples with histopathologic signs of neutrophilic urticaria as opposed to conventional histopathology. Patients with neutrophilic urticaria also had higher white blood cell counts.

CONCLUSIONS

The percentage of samples with neutrophilic urticaria in this series (57.1%) is higher than the percentages reported in the literature, possibly because we tended to biopsy recent lesions. We highlight that the presence of neutrophils in the biopsies of urticaria is a common finding and does not appear to be associated with other diseases.

Urticarial lesions: if not urticaria, what else? The differential diagnosis of urticaria: part I. Cutaneous diseases

Acute urticaria is self-limiting, and a cause can be identified in many patients. Chronic urticaria is a long lasting disease, and patients are commonly examined for an autoimmune origin and for associated diseases. Although the diagnosis of urticaria is straightforward in most patients, it may pose some difficulties at times and it may require a careful differential diagnosis with a number of conditions. Urticarial syndromes comprise both cutaneous and systemic disorders. Part I of this two-part series focuses on the clinical and histologic features that characterize common urticaria and on the cutaneous diseases that may manifest with urticarial lesions and must be considered in the differential diagnosis.

LEARNING OBJECTIVES

After completing the learning activity, participants should be able to distinguish between the typical wheals of urticaria and urticarial lesions suggesting other diagnoses and to assess patients with urticarial lesions in order to exclude or confirm other cutaneous diseases.

Basophil responsiveness in chronic urticaria

Chronic urticaria is a common skin disease without an etiology in the majority of cases. The similarity of symptoms and pathology to allergen-induced skin reactions supports the idea that skin mast cell and blood basophil IgE receptor activation is involved; however, no exogenous allergen trigger has been identified. Recent evidence supports a role for blood basophils in disease expression. Specifically, blood basopenia is noted in active disease with the recruitment of blood basophils to skin lesional sites. In addition, blood basophils display altered IgE receptor-mediated degranulation that reverts in disease remission. In active chronic idiopathic urticaria (CIU) subjects, changes in IgE receptor-signaling molecule expression levels accompany the altered degranulation function in blood basophils. The arrival of therapies targeting IgE has further shown that altered blood basophil degranulation behavior has potential use as a disease biomarker in CIU.