Most Patients With Autoimmune Chronic Spontaneous Urticaria Also Have Autoallergic Urticaria, but Not ViceVersa.

BACKGROUND: Two endotypes of chronic spontaneous urticaria (CSU) associated with mast cell-activating autoantibodies are described, namely autoallergic chronic spontaneous urticaria (aaCSU; with immunoglobulin E [IgE]-anti-autoallergens) and autoimmune chronic spontaneous urticaria (aiCSU; with IgG-anti-high-affinity receptor for the Fc region of immunoglobulin E [FcεRI]/IgE). OBJECTIVE: To investigate the rates of CSU patients with aaCSU and aiCSU. METHODS: We analyzed 111 CSU patients for aaCSU (ie, IgE to thyroid peroxidase, interleukin 24) and for aiCSU (ie, a positive autologous serum skin and Basophil Activation Test plus immunoglobulin G [IgG]-anti-FcεRI/IgE). Clinical and laboratory parameters were compared in patients with aaCSU, aiCSU, and both. RESULTS: Across 111 patients with CSU, 64 (58%) had aaCSU and 9 (8%) had aiCSU. Eight of the 9 aiCSU patients had aaCSU, but only 8 of 64 patients with aaCSU had aiCSU. In total, 7% (8 of 111) of patients had both aiCSU and aaCSU, 41% (46 of 111) had neither, and 16% (18 of 111) tested negative for all markers of aaCSU and aiCSU assessed. Patients with aaCSU or aiCSU are different from those without: patients with stand-alone aaCSU tend to be younger than non-aaCSU patients, aiCSU, and aaCSU/aiCSU overlapping subpopulations. In contrast, patients with aiCSU, with or without aaCSU coexistence, are more often female, have higher levels of thyroid peroxidase autoantibodies (both IgG and IgE), and show more severe quality of life impairment. CONCLUSIONS: Our novel finding that aiCSU coexisting with aaCSU needs to be confirmed in bigger cohorts and multicenter studies. Autoimmunity driven by autoreactive IgE and/or IgG in CSU needs further investigation for better understanding of the pathophysiology.

STAT3 gain-of-function is not responsible for low total IgE levels in patients with autoimmune chronic spontaneous urticaria.

Background: The pathogenesis of chronic spontaneous urticaria (CSU) has not been clarified entirely. Type IIb autoimmune chronic spontaneous urticaria (CSUaiTIIb) is a distinct subtype of CSU that is often difficult to treat and is connected to low levels of total IgE. Previous findings indicate that an enhanced signal transducer and activator of transcription 3 (STAT3) may be responsible for reduced IgE serum levels. Objective: Our aim was to investigate a possible underlying gain-of-function mutation or activating polymorphism in STAT3 that could be responsible for the low levels of IgE in patients with CSUaiTIIb. Methods: We included 10 patients with CSUaiTIIb and low levels of IgE and sequenced selected single nucleotide polymorphisms (SNP) in STAT3 associated with common autoimmune diseases. Exon sequencing was performed for the most relevant exons of STAT3. To test for a gain-of-function of STAT3, we performed a phospho-specific flow cytometry analysis of STAT3 in peripheral blood mononuclear cells before and after stimulation with interleukin-6. Results: No differences were found in the prevalence of the tested SNPs between our patients and a control population. Moreover, we could not find any mutations or variants on the tested exons of STAT3. The function of STAT3 was also not altered in our patients. Conclusion: In total, we could not find any evidence for our hypothesis that low IgE in patients with CSUaiTIIb is linked to mutations in STAT3 or altered activity of STAT3. Thus, it remains to be discovered what causes the low serum levels of IgE in patients with CSUaiTIIb.

Autoimmune Chronic Spontaneous Urticaria Detection with IgG Anti-TPO and Total IgE.

BACKGROUND: Autoimmune chronic spontaneous urticaria (aiCSU) comes with high disease activity and poor response to treatment. Recently, elevated levels of IgG anti-thyroid peroxidase (aTPO) and low levels of total IgE were reported to be common in aiCSU. OBJECTIVE: To investigate how high aTPO and low IgE individually and combined are linked to features of aiCSU, including treatment responses. METHODS: We analyzed records of patients with CSU from 2 independent cohorts (n = 1120) for demographic, clinical, and laboratory parameters and treatment responses. Total IgE and aTPO were measured, and 4 markers of aiCSU were analyzed: autologous serum skin test, basophil activation test (BAT), and blood eosinophil and basophil counts. Cutoff values were greater than or equal to 34 kU/L (high aTPO) and less than 40 IU/mL (low total IgE). RESULTS: One of 10 patients with CSU had both high aTPO and low IgE (aTPO↑IgE↓, 11%, n = 123). aTPO↑IgE↓ was linked to higher age at CSU onset, being female, angioedema, and shorter CSU duration. aTPO↑IgE↓ was associated with markers of aiCSU, that is, BAT and autologous serum skin test positivity, basopenia, and eosinopenia (P < .01 for all). Almost half the patients with aTPO↑IgE↓ (44%, 19 of 43) had a positive BAT result, the best single marker for aiCSU, versus 12% (43 of 344) of patients without aTPO↑IgE↓ (P < .001). Relative risk of showing BAT positivity for a patient with aTPO↑IgE↓ is 3.636 (95% CI, 2.382-5.551). Patients with aTPO↑IgE↓ showed low response rates to antihistamine treatment as compared with patients without aTPO↑IgE↓ (30% vs 47%; P = .01). CONCLUSIONS: Our findings suggest that aTPO↑IgE↓ is a useful diagnostic marker for aiCSU in everyday clinical practice.

Lower IgA Levels in Chronic Spontaneous Urticaria Are Associated With Lower IgE Levels and Autoimmunity.

Background: The pathogenesis of chronic spontaneous urticaria (CSU) is still insufficiently understood. Recent findings suggest that immunoglobulins, in particular IgE but also IgA, play a role in the development of CSU. Objective: Our aim was to assess differences in clinical and laboratory markers between CSU patients with and without lower levels of serum IgA and IgE. Methods: We analyzed the data of 606 patients with CSU by dividing them into four groups based on their IgA and IgE levels. The groups were compared for their spectrum of symptoms, disease activity, concomitant autoimmunity and routine laboratory markers. Autoreactivity was assessed by basophil activation test (BAT). Moreover, IgE-anti-thyroid peroxidase (TPO) was measured. Results: Of the patients with lower IgE levels, 66.5% also had lower IgA levels (r=0.316, p<0.001). Patients with lower IgA and lower IgE levels showed a higher prevalence of recurrent angioedema (p=0.03, p=0.04) and concomitant autoimmunity (p=0.006, p<0.001). Autoreactivity was also found more frequently in patients with lower IgA and lower IgE levels (p=0.003, p<0.001). Reduced basophil counts were linked to both, lower IgA and lower IgE levels (p<0.001), whereas low eosinophil counts were primarily present in patients with lower IgE levels (p=0.04, p<0.001). Patients with elevated IgE-anti-TPO levels had lower IgA (p=0.007) and IgE levels (p=0.001). Conclusion: Lower IgA levels in CSU are linked to lower IgE levels and features of autoimmune urticaria. Our findings encourage to screen CSU patients for serum IgA and IgE levels and to further assess their role as disease biomarkers.