The pathogenesis of chronic idiopathic urticaria: new evidence suggests an auto-immune basis and implications for treatment

The renin-angiotensin system and specifically angiotensin-converting enzyme 2 as a potential therapeutic target in SARS-CoV-2 infections

In March 2019, the global COVID-19 pandemic caused by the novel SARS-CoV-2 coronavirus began. The first cases of SARS-CoV-2 infection occurred in November 19 in Wuhan, China. Preventive measures taken have not prevented the rapid spread of the virus to countries around the world. To date, there are approximately 3 million deaths, and a massive worldwide vaccination campaign has recently begun. SARS-CoV-2 uses the ACE-2 protein as an intracellular carrier. ACE-2 is a key component of the renin-angiotensin system (RAS), a key regulator of cardiovascular function. Considering the key role of ACE-2 in COVID-19 infection, both as an entry receptor and as a protective role, especially for the respiratory tract, and considering the variations of ACE-2 during the phases of viral infection, it is clear the important role that pharmacological regulation of RAS and ACE-2 may take. In this article, we describe the importance of ACE-2 in COVID-19 infection, the pharmacological aspects of a modulation with RAS-modifying agents, new therapeutic strategies, trying to provide a deep understanding and explanation of the complex mechanisms underlying the relationship between the virus and ACE-2, providing opinions and personal hypotheses on the best strategies of therapeutic intervention.

EAACI taskforce position paper: evidence for autoimmune urticaria and proposal for defining diagnostic criteria

An autoimmune subset of chronic spontaneous urticaria is increasingly being recognized internationally, based on laboratory and clinical evidence that has accrued over the last 20 years. This evidence has been reviewed by a taskforce of the Dermatology section of the European Academy of Allergy and Clinical Immunology. Functional autoantibodies in chronic urticaria (CU) patient sera have been demonstrated against IgE and FcεRIα by basophil and mast cell histamine release assays and by basophil activation assays. Antibody specificity has been confirmed by immunoassay, but there is a poor correlation between functionality and immunoreactivity. Approximately 25% of CU patients have a positive basophil histamine release assay and show autoreactivity (a positive autologous serum skin test), whereas 50% are negative regarding both. Functionality of CU sera appears to be complement dependent on mast cells but not exclusively on basophils. Basophil activation by CU sera is predominantly restricted to IgG1 and IgG3 subclasses. Circumstantial evidence for CU being an autoimmune disease comes from an observed association with other autoimmune diseases, a strong association between serum functionality and HLA-DR4 haplotype and the good response of CU patients to immunotherapies. It was proposed that a study should be undertaken to prospectively validate potentially relevant clinical criteria (from the history, examination and routinely available clinical investigations) against a new 'gold standard' for the diagnosis of ACU (positive autoreactivity, functional bioassay and immunoassay) to define preliminary criteria sets for the diagnosis of ACU based on clinical and laboratory features with highest individual sensitivity and specificity.

Plasma levels and skin-eosinophil-expression of vascular endothelial growth factor in patients with chronic urticaria

BACKGROUND

Although chronic urticaria (CU) is often regarded as autoimmune in nature, only less than 50% of sera from CU patients contain histamine-releasing autoantibodies. This suggests that other factors may contribute to its pathogenesis. We evaluated the possible involvement of vascular endothelial growth factor (VEGF), one of the major mediators of vascular permeability, in CU.

METHODS

Eighty consecutive adult patients with CU and 53 healthy subjects were studied. VEGF and prothrombin fragment F(1+2) were measured by enzyme immunoassays. Autologous plasma skin test (APST) was performed in CU patients and, in six of them, skin biopsy specimens were taken from wheals to evaluate the immunohistochemical expression of VEGF and eosinophil cationic protein (ECP).

RESULTS

Plasma VEGF concentrations were higher in CU patients (8.00 +/- 0.90 pmol/l) than in controls (0.54 +/- 0.08 pmol/l) (P = 0.0001) and tended to parallel both the severity of CU and to correlate with F(1+2) levels. APST was positive in 85.1% of patients. VEGF concentration was significantly higher in APST-positive than in APST-negative patients (P = 0.0003). Immunohistochemically, all specimens from patients with CU showed a strong expression of VEGF (P = 0.002) that colocalized with ECP, a classic eosinophil marker.

CONCLUSIONS

VEGF plasma levels are elevated in CU and parallel the disease severity. This supports a possible role of this molecule in CU pathophysiology. Eosinophils are the main cellular source of VEGF in CU lesional skin.

Etiologic aspects and prognostic factors of patients with chronic urticaria: nonrandomized, prospective, descriptive study

BACKGROUND

Studies investigating etiologic factors in chronic urticaria are based on small populations of a few hundred patients. In addition, data on prognostic factors of the disorder are scarce.

OBJECTIVE

To investigate the etiologic and prognostic factors of chronic urticaria on a large population referred to tertiary specialized hospital departments.

METHODS

The study investigated 2,523 patients with chronic urticaria and a negative autologous serum skin test using anamnesis, and the literature suggested laboratory tests for etiologic factors of the disorder. The patients were prescribed cetirizine 10 mg daily plus treatment of any underlying disorders illuminated by the laboratory investigation. The rescue medicine was loratadine 10 mg. The patients were evaluated every 3 months. Comparative statistical methods were used to evaluate the prognostic factors having an impact on the duration of the disorder until resolution of symptoms.

RESULTS

Etiologic factors of chronic urticaria-angioedema were identified in 38.7% of the patients. Physical urticarias had a prevalence of 17.1% in the population under study. Other common etiologic factors identified included infection (7.7%) and autoimmune thyropathy (7.3%). Multiple regression analysis showed that female gender, long duration of the disorder at the initial examination, the presence of angioedema, and physical urticarias are associated with worse prognosis of the disorder, whereas increased self-reported stress and psychiatric disease had no impact on the course of the disorder.

CONCLUSION

A detailed medical history and selective laboratory tests can illuminate etiologic factors in less than 40% of patients with chronic urticaria. Prognostic factors identified to impact the natural history of the disorder could be helpful when designing studies assessing the efficacy of therapeutic agents for chronic urticaria.

Sociodemographic and clinical characteristics, causal factors and evolution of a group of patients with chronic urticaria-angioedema

CONTEXT AND OBJECTIVE

Chronic urticaria-angioedema is a common, multiple-cause complaint. The aim was to investigate the sociodemographic and clinical characteristics, causal and aggravating factors and evolution of urticaria-angioedema.

DESIGN AND SETTING

This was a descriptive prospective study carried out at the Dermatology outpatient clinic of Faculdade de Medicina de Botucatu, Universidade Estadual Paulista (Unesp).

METHODS

A total of 125 patients with chronic urticaria-angioedema were evaluated to obtain sociodemographic data, anamnesis, dermatological and general clinical data and laboratory data, emphasizing causal and aggravating factors and complaint evolution.

RESULTS

Chronic urticaria-angioedema occurred mainly in females (mean age: 35 years), but also in men (mean age: 32 years). White color and living in urban areas also predominated. There was no preferential time for symptoms to appear, and nighttime was the most commonly reported time for clinical worsening. Around half of the patients had urticaria associated with angioedema. There were no associated factors in most of the cases, and stress was the most commonly reported aggravating factor. The cause was ascertained in 37.6% of our cases. The mean duration of follow-up was 11.7 months. Around 60% of the patients evolved with the problem under control, 32% improved, 9% had no change in dermatological condition and only one patient worsened.

CONCLUSIONS

Chronic urticaria-angioedema was more common among middle-aged women. It is a long-term disease, and its cause was explained in about one-third of the patients. Half of the patients presented disease control after treatment lasting an average of approximately one year.

Clinical and Laboratory Examinations in the Subgroups of Chronic Urticaria

BACKGROUND

The aetiology of chronic urticaria is heterogeneous. Physical urticaria (PU) is estimated at around 35%, autoimmune urticaria (AIU) at 25% and chronic idiopathic urticaria (CIU) at 35% of all chronic urticaria cases.

METHODS

Differences in clinical and laboratory parameters among AIU, PU and CIU groups were examined. AIU was diagnosed if the basophil CD63 assay was positive. Demographic data, severity of symptoms and association with allergic and autoimmune diseases were analysed by the aid of a questionnaire. Immunoassays were carried out and the effectiveness of therapy was also investigated.

RESULTS

Concerning the urticaria score, AIU patients had significantly higher total urticaria scores than patients with CIU (p = 0.013), dermatographic urticaria (p = 0.05) or cholinergic urticaria (p = 0.038). Between CIU and dermatographic urticaria and between CIU and cholinergic urticaria patients, we found insignificant differences in the urticaria score (p = 0.707 and p = 0.336, respectively). AIU was more frequently associated with autoimmune diseases in the personal history (p < 0.001) and with other types of urticaria in the family history (p < 0.001). Also, anti-thyroid antibodies were more frequently detected in the AIU group. Antihistamine therapy was less effective in the AIU group (12.8%) than in the PU (70.3%) and CIU groups (68.6%), but there were no significant differences between the CIU and PU groups regarding the effectiveness of antihistamine therapy.

CONCLUSION

The autoimmune subgroup represents the most severe form of chronic urticaria. On the other hand, there were no significant differences between the CIU and PU groups neither in urticaria scores nor in response to antihistamine therapy.

Autoimmunity and complement in the pathogenesis of chronic urticaria

Chronic urticaria is a debilitating skin disease that is believed to have an underlying autoimmune etiology in 35% to 50% of cases. Patients with autoimmune urticaria have functional antibodies in their sera that release histamine from basophils and mast cells. The C5a component of complement is required for mast cell degranulation in this process and at least augments basophil histamine release. In this article, the evidence that is key to our understanding of autoimmunity and complement in the pathogenesis of a subset of patients with chronic urticaria is outlined. Some of the issues in testing for and treating autoimmune urticaria are discussed.

HLA class I and class II antigens in Turkish patients with chronic ordinary urticaria

BACKGROUND

Chronic urticaria is a common disease with an unclear pathogenesis, which may be resistant to therapy. Recent studies have focused primarily on a possible autoimmune basis. AIM. To investigate HLA class I and II antigens in a Turkish population with chronic ordinary urticaria (COU; not physical, vasculitic or contact), and identify susceptible HLA antigens.

METHODS

HLA antigens were investigated in 55 patients diagnosed with COU, using a two-stage microdroplet lymphocytotoxicity test, with 104 healthy and genetically unrelated individuals evaluated as the control group.

RESULTS

HLA Bw4 and HLA DQ1 antigens were significantly higher in the study group (odds ratio (OR) = 2.93, 95% CI 1.47-5.85, P = 0.003 and OR = 7.81, 95% CI 1.96-28.50, P = 0.001, respectively) whereas HLA-A24 antigen was higher in controls (OR = 0.36, 95% CI 0.15-0.86, P = 0.03).

CONCLUSION

We propose that HLA-Bw4 and DQ1 antigens may be responsible for susceptibility to COU while HLA-A24 may have a protective role in the Turkish population.

Lack of correlation between Helicobacter pylori infection and autologous serum skin test in chronic idiopathic urticaria

BACKGROUND

There are controversial reports about the direct role of Helicobacterpylori infection in chronic idiopathic urticaria. The indirect role of H. pylori infection in the induction of pathogenetic antibodies is not fully elucidated either. This study aims to reveal the association of H. pylori infection with autologous serum skin test positivity in chronic idiopathic urticaria (CIU) patients.

METHODS

A total of 47 patients (35 women, 12 men, age range 17-65 years) diagnosed as CIU were included in the study. Autologous serum skin test was performed on all patients. The patients were examined with a commercially available ELISA test for H. pylori-specific antibodies. Gastroscopy with mucosal biopsy and rapid urease tests were proposed to verify the presence of H. pylori infection.

RESULTS

Helicobacter pylori infection was detected in 33 of the 47 patients (70%). No significant relation was found between the autologous serum skin test positivity and the serological and histopathological presence of H. pylori infection.

CONCLUSION

The results of our study suggest that chronic H. pylori infection does not appear to have a role in the induction of autoantibodies in CIU.

Detection of one VH antibody sequence in both healthy donors and urticaria patients

We have previously isolated anti-FcepsilonRIalpha autoantibodies from phage libraries of healthy donors and urticaria patients. Strikingly, the same antibody, LTMalpha15, was isolated from both libraries. Sequence analysis revealed a germline configuration of the LTMalpha15 variable heavy (V(H)) chain with a slightly mutated variable light (V(L)) chain supporting its classification as a natural autoantibody. Distribution analysis of anti-FcepsilonRIalpha autoantibodies by functional or serological tests delivered conflicting data. For this reason we have developed a new real-time PCR to analyse the distribution of LTMalpha15V(H) in healthy donors and urticaria patients. Our new bioinformatic program permitted the design of a minor groove binder (MGB) TaqMan probe that specifically detected the LTMalpha15V(H). We were able to demonstrate a broad range of rearranged V(H) gene copy number without any correlation to the state of health. Monitoring LTMalpha15V(H) gene copy number in a single donor over a period of 70 days revealed a time-related fluctuation of circulating B cells carrying LTMalpha15V(H). We propose that our real-time PCR may serve as a model for the quantification of natural antibody sequences at a monoclonal level.

Urticaria and angioedema

Urticaria and angioedema are commonly encountered complaints in children. Although the diagnosis is clear, establishing an etiology, especially with respect to chronic urticaria, can be challenging. A significant proportion of chronic urticarial cases are now considered to have an autoimmune etiology. This article reviews progress in the field of urticaria and angioedema including developments in pathogenesis, description of laboratory testing, and review of medications. Urticaria and angioedema can usually be controlled by avoidance of triggers, a variety of supportive medications, and reassurance.

Autoimmune urticaria

A growing body of evidence shows that at least 40% of patients with unexplained (idiopathic) chronic urticaria have clinically relevant functional autoantibodies to the high-affinity IgE receptor on basophils and mast cells. The term "autoimmune urticaria" is used for this subgroup of patients presenting with continuous ordinary urticaria. This article reviews the evidence for the autoimmune hypothesis and other nonantibody serum histamine-releasing factors in the etiopathogenesis of urticaria; defines autoimmune urticaria; looks at how autoimmune urticaria fits into existing classifications of urticaria; proposes diagnostic criteria that may be useful to the clinician; and reviews the management implications for patients with this subset of chronic disease.

Clinical and laboratory parameters in predicting chronic urticaria duration: a prospective study of 139 patients

BACKGROUND

Despite the disabling nature of chronic urticaria (CU), little is known about the disease's duration or the efficacy of adopting aggressive therapeutic regimens such as cyclosporine A.

OBJECTIVES

The aim of this study was to evaluate whether parameters such as angioedema, autologous serum test, anti-thyroid antibodies, and total IgE could predict both CU duration and severity.

PATIENTS AND METHODS

One hundred and thirty-nine patients suffering from CU were prospectively followed over a 5-year period for disease duration, severity and the presence of angioedema. Also investigated was the association between these clinical parameters and the subsequent detection of autologous serum test, anti-thyroid antibodies, and total IgE.

RESULTS

CU lasted over 1 year in more than 70% of cases and in 14% it still existed after 5 years. Angioedema co-existed or appeared during the course of CU in 40% of patients and was associated with disease duration. Autologous serum test and anti-thyroid antibodies were found positive in 28 and 12% of patients, respectively, compared to none of normal individuals, P = 0.001. CU duration was associated with the presence of both autologous serum test and anti-thyroid antibodies; however, autologous serum test and not anti-thyroid antibodies was found in association with CU severity.

CONCLUSION

We demonstrate for the first time that CU duration is associated with clinical parameters such as severity and angioedema, and with laboratory parameters such as autologous serum test and anti-thyroid antibodies. The ability to predict CU duration may facilitate decisions regarding the possible early initiation of cyclosporine A as a means by which to reduce disease severity and duration.

Infiltrating cells and related cytokines in lesional skin of patients with chronic idiopathic urticaria and positive autologous serum skin test

In approximately one-third of patients with chronic idiopathic urticaria (CIU), autoantibodies against the high-affinity IgE receptor and/ or against IgE can be detected and a wheal-and-flare response can be provoked by the intradermal injection of autologous serum (ASST). In this study we aimed to further characterize the inflammatory response observed in the subgroup of CIU patients with positive ASST and serum-evoked histamine-release in vitro from basophils in comparison with unaffected skin and healthy donors. An immunohistochemical analysis of infiltrating cells (CD4, MPO, EG1, EG2, tryptase), cytokines (IL-4, IL-5, IFN-gamma), chemokines and chemokine receptors (IL-8, CCR3, CXCR3), and adhesion molecules (ICAM-1, VCAM-1, ELAM-1) was performed on seven selected patients (four males and three females; median age: 45 years; range: 22-57) and five healthy donors. Cytokine evaluation was also performed in five psoriatic patients to obtain an additional control. In spontaneous wheals we observed an increased number of CD4+ T lymphocytes when compared with the controls, and an increased number of neutrophils and eosinophils, whereas mast cells did not show a significant variation. A significant expression for IL-4 and IL-5 could only be observed in lesional skin, while IFN-gamma showed a slight expression in the same site. Chemokine receptors CCR3 and CXCR3 did not show a defined polarized response in either lesional or unaffected skin. An increased expression of all cellular adhesion molecules (CAMs) studied was detected in spontaneous wheals. The lack of a significant difference in the expression of tryptase + mast cells, T lymphocytes, IL-8, CXCR3 and CCR3, a few CAMs between the lesional and unaffected skin of CIU patients suggests a wide immunological activation that involves not only lesional tissues, but possibly extends to the whole of the skin's immune system.

Pruritic dermatoses: overview of etiology and therapy

This review begins with a brief survey of the neurophysiology and neuroanatomy of pruritus, and goes on to describe the etiology of the major allergic and nonallergic pruritic disorders. The etiology of pruritus often suggests the appropriate treatment. For example, urticaria, which is primarily mediated by histamine, is amenable to treatment with H1 antihistamines. Second-generation, nonsedating antihistamines appear to be more effective than sedating antihistamines, perhaps because of better compliance. Other systemic pharmacologic options may be useful in nonhistamine-mediated disorders, for example, immunomodulators for inflammation-induced pruritus or opiate antagonists for atopic dermatitis. Nonpharmacologic measures, such as proper skin care, and physical modalities, such as phototherapy or acupuncture, may also be helpful.

Molecular aspects of allergy

Atopic diseases such as asthma, rhinitis, eczema and food allergies have increased in most industrialised countries of the world during the last 20 years. The reasons for this increase are not known and different hypotheses have been assessed including increased exposure to sensitising allergens or decreased stimulation of the immune system during critical periods of development. In allergic diseases there is a polarisation of the Th2 response and an increase in the production of type 2 cytokines which are involved in the production of immunoglobulin E and the development of mast cells, basophils and eosinophils leading to inflammation and disease. The effector phase of atopy is initiated by interaction with Fc epsilon RI expressed on effector cells such as mast cells and basophils but also found on an ever increasing list of cells. Binding of a polyvalent allergen to the variable part of IgE leads to a cross-link of the receptor that triggers the cell to release histamine and pharmacological mediators of the symptomatic allergic response. Cross-linking of Fc epsilon RI by autoantibodies against the alpha-chain of the Fc epsilon RI, causing subsequent histamine release is thought to be involved in the pathogenesis of other diseases such as chronic idiopathic urticaria (CIU). To date, most therapeutic strategies are aimed at inhibiting and controlling components of the inflammatory response. Recently, new treatment strategies have emerged that focus on the development of preventive and even curative treatments. The most promising therapeutic approaches are aimed at inhibiting the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic anti-IgE or anti-Fc epsilon RIalpha autoantibodies. Clinical trials in humans using an humanised anti-IgE antibody showed that this antibody was well tolerated and reduced both symptoms and use of medication in asthma and allergic rhinitis. Thus interruption of the atopic cascade at the level of the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic antibodies is effective and represents an attractive therapy for the treatment of atopic disease.

Evaluating chronic urticaria patients for allergies, infections, or autoimmune disorders

Urticaria is a common disorder affecting one-fifth of the world's population. The pathophysiology is characterized by an increased propensity for mast cell degranulation with the release of potent mediators into the dermal and subdermal tissues with resulting vasoactive, chemotactic, and inflammatory effects. The final clinical manifestation of the typical urticarial lesion is the effect of several diverse effects and causes. The general classification is acute, chronic, and physical urticaria. In general, allergenic triggers can be identified in between 60-80% of acute urticarias. Physical urticarias are characterized by the onset after the specific inciting stimulus, which can reproduce the characteristic lesion which is usually of shorter duration (with the exception of delayed pressure urticaria). Chronic idiopathic urticaria is associated with thyroid autoimmunity and, more recently, anti-mast cell receptor antibodies. An extensive work-up is usually not indicated or helpful in identifying a cause. Food or other allergens are rare causes of this type of presentation. The evaluation and work-up is dependent on clues identified by history. The treatment is removal of specific and non-specific triggers and the use of symptomatic medications generally attenuating the mediator effects.

Evaluation of chronic urticaria in patients with Hashimoto thyroiditis

The coincidence of Hashimoto thyroiditis (HT) and chronic idiopathic urticaria (CIU) is a commonly observed phenomenon in western New York. Previous literature suggested that there may be a direct relationship between them. We undertook these studies to determine whether humoral or cell-mediated mechanisms might link HT and CIU. Skin biopsies from patients with CIU, with or without HT, were indistinguishable by light microscopy. No immune complex deposition was observed, although only the skin from patients with CIU and HT contained perivascular fibrin deposits. Similarly, immunohistochemical studies evaluating cellular expression of CD3, CD4, CD8, CD20, and CD68 failed to differentiate between CIU with or without HT. Analysis of Vbeta restriction in thyroid tissue of patients with HT and the skin of patients with CIU and HT by in situ polymerase chain reaction failed to reveal any oligoclonal T-lymphocyte subpopulations. In contrast, only patients with CIU and HT had anti-FcepsilonRI antibodies in their sera that could induce degranulation of normal basophils. Some sera from patients with CIU and HT caused degranulation of normal basophils in the absence of anti-FceRI. The factor causing basophil degranulation in these sera was not determined. Patients with CIU and HT failed to improve clinically with thyroid replacement therapy. All CIU patients were equally well managed with symptomatic therapies. In conclusion, HT likely represents a marker of other autoimmunity, rather than being a direct causative agent in CIU. Management of CIU, with or without HT and with or without anti-FceRI antibodies, should be the same. Future studies will have to examine whether cell-mediated responses participate in CIU, especially in association with HT.

Anti-FcepsilonRIalpha serum autoantibodies in different subtypes of urticaria

BACKGROUND

In recent years, a histamine-releasing anti-FcepsilonRIalpha autoantibody has been demonstrated in about one-third of patients with chronic urticaria. However, its clinical significance is still unclear. The objective was to detect a possible correlation between the occurrence of the anti-FcepsilonRIalpha autoantibody and the clinical type or cause of urticaria.

METHODS

Sera from 66 consecutively seen in- and outpatients with various types of urticaria and five healthy controls were examined for the presence of anti-FcepsilonRIalpha autoantibodies with a sandwich ELISA technique. In addition, basophil histamine release was studied in 13 autoantibody-positive sera.

RESULTS

Anti-FcepsilonRIalpha autoantibodies were found in 17/48 patients with chronic urticaria, in 2/4 with angioedema, in 1/2 with urticarial vasculitis, and in 2/11 with dermographic urticaria. However, no anti-FcepsilonRIalpha autoantibodies were detected in acute, cold, or delayed-pressure urticaria; in urticaria pigmentosa; or in normal controls. Of all chronic urticaria patients, 22 were classified as idiopathic since no underlying cause could be found. Of this group, seven were seropositive for anti-FcepsilonRIalpha. However, anti-FcepsilonRIalpha was also found in patients who went into remission after treatment of identified causes; namely, in one with type I allergy, one with drug intolerance, one with Helicobacter infection, and six with food intolerance. The autoantibody was also detected in 2/4 patients with associated autoimmune diseases. Functional activity was shown in basophil histamine release in 3/4 autoantibody-positive sera of patients with chronic idiopathic urticaria and in 4/6 autoantibody-positive sera of patients who went into remission after the treatment of underlying causes.

CONCLUSIONS

These data confirm that anti-FcepsilonRIalpha autoantibodies in urticaria are mostly found in chronic urticaria. Furthermore, their detection independently of the apparent cause of the urticaria suggests that as yet unidentified mechanisms must be operative, possibly related to the chronic inflammatory process and/or individual predispositions that favor their induction.

Immune aberrations in B and T lymphocytes derived from chronic urticaria patients

To investigate the pathophysiology of chronic urticaria (CU) in light of the abundant evidences that it is an autoimmune disease and to define some cellular markers in B/T lymphocytes that could be of pathogenic significance, we investigated 14 patients suffering from CU, compared to 7 contact dermatitis patients and 10 normal control individuals. We tested the expression of CD5, B7.1 (CD80), CD23, and CD25 on B cells and of CD(40L)) and CD25 on T cells from all studied individuals. We also tested B cell proliferation upon their activation followed by dexamethazone induced inhibition of proliferation. The expression of bcl-2 protein in activated lymphocytes from normal individuals was compared to that of contact dermatitis and CU patients. CD(40L) expression was found significantly higher on in (vitro activated CD3 [with phorbol myristate acetate (PMA) and ionomycine Ca2+ at 12 hr of culture] from CU patients compared to that of contact dermatitis and normal individuals. Whereas the proliferation of activated B cells from CU patients was higher, dexamethazone-induced inhibition of B cell proliferation was found statistically similar in both groups yet lower in B cells from most severe CU patients. We demonstrate a higher bcl-2 expression in activated B and T lymphocytes of severe CU patients compared to that of moderate CU and both contact dermatitis and normal individuals. The increased expression of CD(40L) on activated T cells might play a role in the polyclonal increased B cell proliferation of CU patients. This increased proliferation accompanies the finding that activated B and T lymphocytes from these patients demonstrate increased bcl-2 expression. The resistance of some B cells to dexamethazone-induced inhibition of proliferation encourages us to investigate the possibility that B cells from some CU patients might develop rescue mechanisms from activated cell death. These findings provide further evidence that CU is indeed an autoimmune disease, although its precise nature has yet to be fully elucidated.

Assessment of urticaria and angio-oedema

There are many types of urticaria and the principal form of assessment is by clinical history and examination. Urticarial weal formation involves acute, reversible vasodilatation and increased vascular permeability. If the process is deeper the more diffuse swelling is termed angio-oedema. The major types of urticaria include allergic, physical and idiopathic forms. In allergic urticaria, IgE-mediated degranulation of mast cells results in weals of short duration which typically respond well to antihistamines. Physical urticarias are induced by physical insults including pressure, scratch, cold, etc. The distribution and duration of individual weals may suggest the causal factor. Chronic idiopathic urticaria can be very variable, with individual weals lasting between 90 min and 24 hours. Longer-lasting weals are less responsive to anti-histamines and clearly involve other mediators. When long-lasting weals fade leaving a bruised appearance urticarial vasculitis is present which may only respond to systemic corticosteroids. In a proportion of individuals with chronic idiopathic urticaria, auto-antibodies are present with specificity for the high affinity receptor for IgE or sometimes, for IgE itself. In general laboratory tests for allergic factors or other assessments of general health are completely unhelpful.

Most chronic urticaria is food-dependent, and not idiopathic

Although chronic urticaria is generally thought to be mostly idiopathic, we have recently provided convincing evidence that in the majority of patients, food ingredients provoke the symptoms and sustain the disease. On a diet largely avoiding preservatives, dyes and natural pseudoallergens, 73% of patients experienced remission of more than 6 months duration, starting within the first 3 weeks after initiation of the diet. This response rate is clearly higher than the reported 24% spontaneous remission rate over the same time period. The specificity of the dietary effect was proven 1) by double-blind provocation with pureed pseudoallergen-low versus -rich food and 2) by induction of a clinical response to a 3-week diet low in pseudoallergens, but not to a standard diabetes diet in 3 patients studied in a double-blind crossover design. On double-blind, placebo controlled oral provocation, only 18% of diet-responsive patients reacted to known food preservatives and dyes, but 71% to pureed tomatoes and 44% to their steam extracts. These findings identify naturally occurring pseudoallergens in food as major elicitors of chronic urticaria. In contrast, autoantibodies against Fc epsilonRIalpha have been identified in only about 30% of chronic urticaria patients, and evidence for their truly causative role is still lacking since therapeutic measures work in patients irrespective of the presence or absence of the autoantibodies. For both food intolerance and Fc epsilonRIalpha-autoantibodies in chronic urticaria, the associated pathomechanisms are however still in need of clarification. Meanwhile, the diet-responsiveness in the majority of patients opens new perspectives for the management of chronic urticaria.

Etiologic aspects of chronic urticaria

BACKGROUND

Urticaria is a common disease that is always a challenge to the dermatologist due to its evasive etiology.

PATIENTS AND METHODS

One hundred and seven chronic urticaria patients were studied. Routine laboratory investigations were performed and Helicobacter pylori (H. pylori) immunoglobulin G (IgG) antibody determinations, autoimmune reactivity, infections, allergies, and hyperreactivities were investigated.

RESULTS

Pathologic findings were seen in 92 patients. Concomitant diseases suggesting autoimmune reactivity were detected in nine patients and, in 16 patients, infections including maxillary sinusitis, streptococcal tonsillitis, and tooth infection were found. Elevated total IgE level was detected in 37 out of 75 patients and positive skin prick test results in 47 out of 91 patients. Fifty-five patients had a history of recent dyspeptic symptoms. A diagnosis of adult celiac disease was made in two patients and, additionally, IgA antigliadin antibodies were seen in four patients. H. pylori IgG antibodies were found in 40 out of 107 patients. Active gastritis was verified by esophagogastroduodenoscopy in 30 out of 32 patients with positive Helicobacter staining in 24 samples. An elevated IgE level was detected in 64% of H. pylori-positive and in 39% of H. pylori-negative patients.

CONCLUSIONS

In this study, several findings suggesting aberrant immunologic activation were detected in chronic urticaria patients. Inflammation in the gastrointestinal tract, e.g. caused by H. pylori infection, may have an important role in the etiology of chronic urticaria.

Low-dose cyclosporin A in the treatment of severe chronic idiopathic urticaria

In a limited number of severe chronic idiopathic urticaria (CIU) patients, low-dose cyclosporin A (CsA) treatment was found to be effective. This open study aimed to extend this clinical observation and determine the safety of treatment with CsA. In addition, it aimed to determine the prevalence and characteristics of the autologous serum skin test (AST) in such patients, and whether this test is affected by CsA treatment. Thirty-five patients who suffered from severe CIU (score 3), and who were followed for 6 months (using a clinical urticaria-severity score [range 0-3]) were divided into three groups: 19/35 were treated for 3 months with low-dose CsA, and thereafter followed for an additional 3 months; 6/35 dropped out of protocol treatment; and 10/35 untreated patients (followed for the same period) served as a disease controls. In the treated group, no side-effects were observed, and by the end of treatment, 13/19 (68%) patients were in full remission (score 0) and the remainder scored 1. In contrast, the 10 CsA-untreated patients scored 3 for the whole follow-up period of 6 months. Positive AST was found in 14/35 (40%) of patients, whereas none were detected in 20 healty control subjects. AST neither correlated with disease activity nor predicted response to treatment. This uncontrolled study shows that low-dose CsA is effective in treating CIU patients, and can be given safely for 3 months. However, CIU patients requiring initially high doses of glucocorticosteroids and with a long clinical history are less amenable to CsA treatment.

Histamine: the quintessential mediator

Histamine is unique in being the only substance described to date which fulfils all of the criteria established by Dale for an inflammatory mediator. Thus, histamine is known to cause the "Triple Response" of Lewis and to act via H1 and H2 receptors to produce vasodilation and increased vascular permeability; elevated levels of histamine are found in inflamed tissue; histamine is produced and stored in mast cells and there are established mechanisms for histamine release via mast cell surface receptors; and antihistamines alleviate the clinical manifestations of histamine release. There have been several recent advances in our understanding of histamine pharmacology and of the pathomechanisms of chronic idiopathic urticaria (CIU), a disease in which histamine plays an important role. Two new histamine receptors have been identified, the inhibitory (H3) receptor and the intracellular (H(ic)) receptor involved in cell proliferation. There is now evidence that mast cell derived histamine release in patients with CIU is due to an autoimmune disease, mediated by autoantibodies to the alpha-subunit of the high affinity IgE receptor on mast cells and basophils. Removal of these autoantibodies by plasmapheresis, or treatment with intravenous immunoglobulins may cause clinical remission. Cyclosporin A has also been found to be of benefit to some patients with CIU probably due to a mast cell "stabilising" effect, leading to reduced release of histamine and other mediators. This article reviews our current knowledge on histamine, its role, receptors and mechanisms for release.

Characteristics of histamine-releasing activity in the sera of patients with chronic idiopathic urticaria

BACKGROUND

The serum histamine-releasing activity (HRA) found in a sizable percentage of patients with chronic idiopathic urticaria (CIU) has been partially characterized. However, the variable effect of individual HRA+ sera in basophils of different donors and the relationship of HRA to the clinical course require further investigation.

OBJECTIVE

The study was performed to characterize the HRA found in sera of some members of a sizable group of carefully evaluated patients with CIU.

METHODS

Sera of 70 patients with CIU, evaluated with a standard protocol, were screened for increased HRA. HRA+ sera were fractionated, heated, and tested on unaltered and altered basophils obtained from a panel of normal donors. HRA levels were compared with concomitant clinical manifestations.

RESULTS

HRA+ sera were found in 30% of our patients with CIU, HRA was predominantly in the IgG fraction, sensitive to 56 degrees C heating for 4 hours, and generally reacted more with IgE-stripped basophils. Considerable variation in the degree of response to HRA+ sera in the basophils of different normal subjects did not correlate with the degree of response of these cells to heterologous anti-IgE antiserum. Serum HRA levels were generally much lower when symptoms decreased in these patients with CIU.

CONCLUSION

Serum HRA from patients with CIU appears to bind most commonly to the IgE receptor and may be a marker of clinical disease activity. HRA appears in an IgG-containing fraction of the serum and may contain IgE in some cases.

Dermal mast cell activation by autoantibodies against the high affinity IgE receptor in chronic urticaria

Previous studies identified autoantibodies against the IgE high affinity receptor alpha-chain, Fc epsilon RI alpha, in sera of selected patients with severe chronic idiopathic urticaria. We have now determined the incidence of anti-Fc epsilon RI alpha autoantibodies in a group of 163 patients. Intradermal injection of autologous serum caused skin reactions indicative of mast cell degranulation in 98 (60%) patients. Based on histamine release from IgE-sensitized and nonsensitized basophil leukocytes of healthy donors, we detected anti-Fc epsilon RI alpha autoantibodies in sera from 38 (23%) urticaria patients and evidence for anti-IgE antibodies in a further nine patients. The sera that released histamine from basophils induced histamine release (4-34%, n = 12) from mast cells in incubated skin slices. Protein-G affinity chromatography of sera demonstrated that mast cell histamine release was IgG-mediated. Preincubation of sera or the IgG fraction with a recombinant alpha-chain of Fc epsilon RI inhibited histamine release from mast cells and basophils. Further studies with the mouse anti-human Fc epsilon RI alpha antibody 29C6 showed that mast cells and basophils were similarly sensitive to IgG-mediated direct cross-linking of Fc epsilon RI, with 0.01-1.0 micrograms/ml 29C6 evoking histamine release in each case. These studies demonstrate that circulating levels of anti-Fc epsilon RI alpha autoantibodies mediate histamine release from skin mast cells in vitro and, taken together with in vivo evidence of mast cell degranulation following intradermal injection of autologous serum, support the concept that anti-Fc epsilon RI alpha autoantibodies are relevant to the pathogenesis of severe chronic urticaria in about 25% of patients.

Dermatology

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Anti-IgE therapy

Controlling the IgE response at either the synthesis level or the effector phase should have a profound impact on the allergic cascade. For more than a decade, researchers have focused on ways of interfering with the binding of IgE to its high-affinity receptor on proinflammatory cells. Several approaches have also been taken to antagonize the complex interplay of cytokines and cell-associated molecules (CD40, CD23) that are implicated in IgE synthesis. Recently, anti-IgE antibodies have been developed that are potent IgE antagonists. These antibodies are currently under clinical investigation as potential therapeutics for allergic disease.