Chronic spontaneous urticaria (CSU) is a common cutaneous disease, affecting around 0.3% to 1% of the population worldwide [
CSU is a heterogeneous disease with various clinical characteristics. Therefore, it could prove informative and is clinically important to identify biomarkers able to classify patients according to their phenotype based on underlying immunological mechanisms. Moreover, such an approach would enable us to stratify patients according to their clinical prognosis [
The association between thyroid autoimmunity and CSU has been evaluated in multiple studies [
The aim of this study was to evaluate the clinical characteristics of CSU patients according to the presence of anti-TPO IgE in serum. We also investigated the role of anti-TPO IgE in exacerbations affecting the skin of these patients.
The population assessed in this crosssectional study comprised patients recruited from the URTICA cohort (URTICA: Urticaria Research of Tropical Impact and Control Assessment) during the period 2017 to 2018 [
Of the 155 patients with CSU who agreed to participate in the study, 55 were excluded owing to difficulties with serum sample collection during the exacerbation period; the final study population was 100 patients.
CSU was defined as the recurrence of hives, with or without angioedema, persisting for at least 6 weeks. The disease was diagnosed by an allergist or dermatologist. The exclusion criteria were systemic disease that could explain the hives and immunodeficiency, dermatitis, or any other disease that could alter the results of the serum tests. We also excluded pregnant women, patients with physical or mental disabilities, patients with decompensated cardiovascular disease, and patients with a chronic disease that could compromise challenge testing.
We used the Dermatology Life Quality Index to evaluate the impact on quality of life and the Urticaria Activity Score (UAS) to measure disease severity. The UAS was carried out for at least 7 consecutive days; if the patient present an
The main objective was to evaluate the relationship between anti-TPO IgE and triggers of skin exacerbations in CSU such as NSAIDs, foods, and physical activity. As a secondary objective, we compared levels of anti-TPO IgE in periods of clinical control (UAS 0) or exacerbation of urticaria (
Serum samples were collected from all patients during a period of clinical control and during 2 periods of exacerbations to determine anti-TPO IgE levels. At least two weeks were waited between the two exacerbation serum samples.
Patients taking daily second-generation antihistamines had to suspend their medication for at least 4 days before the challenge test. Any other drug that could have affected the outcome of the challenge test was suspended for the minimum time necessary before the challenge was performed. When patients had an exacerbation before the challenge test, a new appointment for a challenge test was offered.
According to the protocol, if patients had experienced a clear anaphylactic reaction within 1 hour of exposure to the trigger during at least 12 months before recruitment, the challenge test was avoided and considered positive. However, none of the patients met this criterion so we did not exclude any patient from the challenge tests. The protocols used for challenge tests were based on those proposed in international guidelines [
The 5 most common self-reported sources of inducible urticaria (dermographism, cold, exercise, water, and pressure) [
Oral challenge tests with food were blinded for the patient and placebo-controlled. The test was performed in patients with self-reported skin exacerbation of urticaria or angioedema. Patients received a portion equivalent to the expected daily intake of the food investigated. Blinding of food was done by mixing the food tested with other foods that the patient tolerated and that would help neutralize or at least decrease the taste of the food tested. Before the challenge test, specific IgE (sIgE) determination and skin prick testing (SPT) with the suspect food were performed with food extracts. In patients without atopy, challenge tests were performed by administering the total food serving in 2 portions separated by 1 hour (10% and 90% of the total serving, respectively). In patients with atopy, food was administered in 4 portions (10%, 20%, 30%, and 40%). The evaluation period after the challenge test was 4 hours, and the patients were instructed to notify the physician of delayed reactions. Delayed reactions that occurred in the first 24 hours after the provocation could be associated with the challenge; in that case, according to the protocol, we would repeat the challenge again to confirm the relationship.
Oral challenge tests with NSAIDs were blinded for the patient and placebo-controlled. The test was performed in patients with self-reported skin exacerbation caused by NSAIDs. The equivalent to 1 daily dose of the drug was administered in 2 doses (10% and 90%) separated by 1 hour. In patients with a history of severe reactions (e.g., anaphylaxis or respiratory distress), the daily dose was administered in 4 steps (10%, 20%, 30%, and 40%) separated by periods of 1 hour. After the final dose was administered, the observation period at the clinic was 4 hours, and patients were also instructed to report any delayed reactions outside the clinic.
Some patients required a challenge test with 2 or more substances (e.g., a food and a medication). In patients with a history of reaction to 2 NSAIDs or 2 foods with crossreactivity, the first test was performed with the least probable trigger (e.g., meloxicam). The second trigger was tested only if the result with the first trigger was negative (e.g., ibuprofen).
When patients were discharged, they were advised that in the case of a late reaction, they should take a photograph and/or visit their health center. A challenge test was considered positive when the patient had hives or angioedema during the evaluation period. Other symptoms such as wheezing, diarrhea, and vomiting were also indicative of a positive test but were recorded separately if hives or angioedema were not present.
For challenge tests with food or medication, the placebo was administered at the beginning of the test. Subsequently, the physician performing the test could perform new administrations of placebo. The doctor performing the provocation was free to administer additional doses of placebo if, for example, he/she considered that the patient’s pruritus could be due to anxiety or nerves of the test, always leaving an interval of at least 20 minutes with the next dose.
Recombinant TPO was obtained as previously described [
The statistical analyses were performed using IBM SPSS Statistics for Windows, version 21.0 (IBM, Armonk, NY, USA). The mean was reported for descriptive variables. The Mann–Whitney test was used to compare anti-TPO IgE levels according to the cut-off. Pearson’s
Based on the standard deviation observed in a control group of 100 healthy controls, in patients with positive anti-TPO IgE during the clinical control period, an increase in anti-TPO IgE levels during skin exacerbation was defined as significant if it was greater than 30% of the value recorded during the period of clinical control. In patients with negative anti-TPO IgE during the clinical control period, an increase was considered significant if the OD was greater than 0.304 during the exacerbation. Control subjects were patients over 18 years of age (29 confidence interval; CI 24–38) without previous or actual history of skin or autoimmune diseases, angioedema, or anaphylaxis.
Statistical analysis for multiple comparisons was done, for comparisons among more than two study groups; we use the Kruskal Wallis test, for quantitative variables (e.g., IgE levels).
Most patients were female (Table
General characteristics. The general characteristics are presented in the 100 patients and in their two groups according to the presence or none of anti-TPO IgE. The “
Variables | (+) anti-TPO IgE |
(-) anti-TPO IgE |
|
---|---|---|---|
Age | 30 (16 to 48) | 29 (16 to 50) | Ns |
Age at onset (y) | 20 (6 to 48) | 23 (6 to 48) | Ns |
Sex: female, |
28 (65.1%) | 35 (61.4%) | Ns |
Total IgE (IU/ml) | 0.04 | ||
Atopy, |
25 (58.1%) | 13 (22.8%) | 0.04 |
Asthma, |
8 (18.6%) | 4 (7%) | 0.05 |
Rhinitis, |
19 (44.1%) | 21 (36.8%) | Ns |
Autoimmune diseases | 9 (20.9%) | 9 (15.7%) | Ns |
DLQI score, |
Ns | ||
UAS score, |
Ns |
Thirty patients had positive anti-TPO IgE during the clinical control period (Figure
Groups of patients according to anti-TPO IgE level. Patients were evaluated during a period of clinical control (UAS 0) and two periods of urticaria exacerbation (
In the 43 patients with anti-TPO IgE elevation during the exacerbation of urticaria, we measured the levels of Der f, Blo t, and Can f; none of them had a significant increase in ration at baseline levels (
Seventy patients (70%) suspected at least 1 physical trigger, and 40 identified 2 or more. The most common self-reported trigger was dermographism (35%) (Figure
Prevalence of inducible urticaria according to self-reporting and challenge testing. Prevalence of inducible urticaria (IU) according to self-report and challenge test. Patients with (+) anti-TPO in dark green and (-) anti-TPO IgE in light green.
Thirty-four patients (34%) had a positive challenge test result (Figure
Patients with negative anti-TPO IgE had a higher frequency of symptomatic dermographism, pressure urticaria, and cold urticaria than those in patients with positive anti-TPO IgE (Table
Inducible urticaria according to challenge testing and anti-TPO IgE. Comparison of patients with or without anti-TPO IgE according inducible urticaria.
Inducible urticaria according to challenge testing | (+) anti-TPO IgE |
(-) anti-TPO IgE |
|
---|---|---|---|
Patients with any inducible urticaria | 10 (23.2%) | 24 (42.1%) | 0.03 |
Dermographism | 7 (16.2%) | 17 (29.8%) | 0.03 |
Pressure | 1 (2.3%) | 5 (8.7%) | 0.04 |
Ice | 2 (4.6%) | 10 (17.5%) | 0.02 |
Water | 0 | 0 | N/A |
Exercise/cholinergic | 0 | 2 | N/A |
Additional physical challenge testing was performed in 4 patients whose exacerbations were strongly suspected of being caused by other triggers such as heat or sun exposure; the 4 challenges were negative (data not shown).
Sixty-four (64%) patients reported a reaction with foods (Figure
Prevalence of self-reporting, sensitization, and positive challenge test to foods. Food challenge tests were performed using the suspected food in patients who self-reported food allergy (
We performed a total of 169 food challenge tests in 64 patients including those with a positive SPT result, although none were positive. During the administration of the placebo, 6 patients reported itching, but none presented objective reactions; therefore, the challenge test was continued and was tolerated in all cases, so there was not a positive challenge test with foods.
Thirty-eight patients reported at least 1 reaction with NSAIDs (Figure
Comparison of NSAID self-report and challenge test results. A challenge test with the suspected NSAIDs was performed in patients who self-reported drug reaction. Each patient was challenged with the NSAIDs (≥1) that he/she had suspected of exacerbating the urticaria. N/A: not applicable; ASA: acetylsalicylic acid.
Fourteen patients had a positive challenge test result with NSAIDs; 2 required treatment with adrenaline. Nine of the 14 patients had a positive anti-TPO IgE level; this result was more frequent than in patients without anti-TPO IgE (Figure
The clinical characteristics of patients with anti-TPO IgE differed from those of patients without anti-TPO IgE (Figures
Anti-TPO IgE groups. The clinical characteristics of patients with or without anti-TPO IgE are represented in (a). (b) represents the interaction between patients with positive anti-TPO (blue), NSAID challenge testing (green), and inducible urticaria (purple). (c) and (d) present the frequency of patients with reactions to NSAIDs (
NSAIDs
inducible urticaria
No statistically significant differences were observed when patients were stratified according to anti-TPO IgE levels during the clinical control or exacerbation periods (Figures
Autologous serum skin test (ASST) was more frequently positive in patients with positive anti-TPO IgE; nevertheless, it was not statistically different than patients with negative anti-TPO IgE (65% vs 58%,
CSU is a heterogeneous disease with multiple clinical characteristics. Patients may have angioedema, inducible urticaria, reactions to NSAIDs, or autoimmune diseases. Biomarkers can improve our understanding of the underlying mechanisms of this disease [
The presence of anti-TPO IgE may play a role in the development of CSU, as supported by data from
Several experimental studies support a relationship between IgG and IgE antibodies against self-antigens and urticaria; however, there are many questions that do not yet have answers but different studies support that these antibodies can activate and induce the release of histamine in the basophils of many patients with urticaria. In the case of anti-TPO IgE, it was recently demonstrated that passive transfer of serum from a patient with CSU and anti-TPO IgE to a healthy subject without CSU or anti-TPO IgE induced the formation of a wheal after TPO exposition [
Previous studies (mostly with a retrospective design and small samples) have evaluated anti-TPO IgE as a possible prognostic biomarker of the duration and severity of CSU. However, evidence is inconsistent or weak [
Various underlying mechanisms may intervene in the development of CSU in patients without anti-TPO IgE, for example, IgG against Fc
We did not evaluate the therapeutic response of patients with CSU, although some studies suggest that high levels of total IgE have been associated with a better response to omalizumab [
According to the levels of anti-TPO IgE during periods of clinical control and skin exacerbation, we identified 3 groups of patients with positive anti-TPO IgE. The responses according to the levels of anti-TPO IgE led us to ask whether these 3 groups were part of the same endotype at different time periods or whether they represented different mechanisms. The answer to this question may also help to clarify whether the presence of anti-TPO IgE in healthy subjects represents a risk for the development of urticaria. It is necessary to carry out prospective studies to resolve these issues.
Differences in the prevalence of inducible urticaria and drug reactions have been reported in different parts of the world [
While our results are encouraging, our study is subject to limitations. Patients who initially had a value below 0.304 OD and during the exacerbation exceeded this value were considered positive since they exceeded the cut-off. However, in patients with a value close to the cut-off, this event could occur due to the expected variation between two tests (interassay variation of 10%) [
In conclusion, anti-TPO IgE could be a useful biomarker for stratifying patients according to clinical phenotypes. Elevation of anti-TPO IgE during exacerbations supports a possible association between this autoantibody and the pathogenesis of urticaria which should be explored in more detail. This article presents new questions and new challenges that must be investigated. What could be driving the change in IgE anti-TPO levels? Which changes in IgG anti-TPO antibodies have to be addressed?
Chronic spontaneous urticaria
IgE antibodies against thyroid peroxidase
Inducible urticaria
Nonsteroidal anti-inflammatory drugs
Optical density
Urticaria Activity Score.
This study was based on data from the “URTICA” cohort.
A summary of this article was previously published in the “Allergy” journal during the congress of the European Congress of Allergy Asthma and Immunology (abstract number TPO857).
We declare no conflicts of interest.
We thank Dr. Javier Estarita and Dr. Carolina Salemi for their help in the clinical follow-up of patients and the Clinical and Experimental Allergy Group and Foundation “IPS Universitaria” from the University of Antioquia (Medellín, Colombia) for funding this study.
Supplementary Table 1: physical challenge tests stratified by anti-TPO groups. Comparison of anti-TPO IgE groups. Group 1: patients with anti-TPO IgE during the clinical control period and significantly increased levels during an exacerbation (