IgG anti-integrin αvβ6 autoantibodies (IgG anti-αvβ6) have been described as highly sensitive and specific markers of ulcerative colitis (UC) in the sera of Japanese inflammatory bowel disease (IBD) patients. We aimed to evaluate the diagnostic performance of IgG anti-αvβ6 as a biomarker in Swedish patients with IBD or irritable bowel syndrome (IBS). The study included adult UC (n = 59), Crohn’s disease (CD, n = 38), and IBS patients (n = 100). Partial Mayo score and Harvey–Bradshaw index were used to assess disease severity for UC and CD, respectively. Serum levels of IgG anti-αvβ6, reported as absorbance units (AU), were measured using an in-house ELISA where the 95th percentile of 76 healthy controls defined positivity. Faecal calprotectin (fCP) was measured using a commercial assay. The majority of the IBD patients were on medical treatment, and many were in remission (UC: 40.7%; CD: 47.4%). Seventy-one percent of the UC patients, 74.2% of CD patients, and 23.1% of the IBS patients had fCP test results >50 mg/kg. The UC group had significantly higher IgG anti-αvβ6 levels (median: 1.76 AU) than the CD and IBS groups (0.34 and 0.31 AU, both p < 0.0001). The diagnostic sensitivity of IgG anti-αvβ6 in UC was 76.3%, and the specificities were 79.0% (vs. CD) and 96.0% (vs. IBS). The IgG anti-αvβ6 levels related to disease severity of the UC patients (p < 0.01–0.05). Our study shows that IgG anti-αvβ6 is associated with UC in Swedish IBD patients and that the levels of the autoantibodies reflect disease severity. IgG anti-αvβ6 could be an attractive complement to fCP in the diagnostic work up of IBD patients.

Our aim is to assess the efficacy of fecal calprotectin (fCP) and fecal eosinophil-derived neurotoxin (fEDN) as diagnostic markers of cow’s milk protein allergy (CMPA) and for monitoring the infants’ response to a non-IgE mediated cow’s milk protein (CMP)-free diet. We prospectively recruited infants aged 0 to 9 months. Stool samples were taken from 30 infants with CMPA, 19 with mild functional gastrointestinal disorders, 28 healthy infants, and 28 children who presented mild infections. Despite the fact that levels of fCP and fEDN in CMPA infants were higher than in healthy infants at month 0, differences for both parameters did not reach statistical significance (p-value 0.119 and 0.506). After 1 month of an elimination diet, no statistically significant differences in fCP with basal levels were found (p-values 0.184) in the CMPA group. We found a high variability in the fCP and fEDN levels of young infants, and discrepancies in individual behavior of these markers after a CMP-free diet was started. It seems that neither fCP nor fEDN levels are helpful to discriminate between healthy infants and those with signs or symptoms related to non-IgE-mediated CMPA. Additionally, it is debatable if on an individual basis, fCP or fEDN levels could be used for clinical follow-up and dietary compliance monitoring. However, prospective studies with larger populations are needed to draw robust conclusions.

Background and Aims: The diagnostic and prognostic properties of anti-integrin αvβ6 immunoglobulin G (IgG) autoantibodies in ulcerative colitis (UC) are poorly understood. We aimed to assess the diagnostic performance of anti-integrin αvβ6 autoantibodies and examine their association with disease outcomes. Methods: Serum samples from a Swedish inception cohort of patients with suspected inflammatory bowel disease (IBD, n = 473) were analyzed using an in-house fluorescence enzyme immunoassay based on EliA technology. Findings were validated in a Norwegian population-based inception cohort (n = 570). Diagnostic performance was assessed by calculating the area under the curve (AUC) with 95% confidence intervals and determining sensitivity and specificity. Reclassification was evaluated using the net reclassification index. Results: In the discovery cohort, patients with UC, IBD-unclassified, or colonic Crohn’s disease exhibited higher median autoantibody levels compared to symptomatic and healthy controls. In the validation cohort, the autoantibody demonstrated 79% sensitivity and 94% specificity for UC vs symptomatic controls at a cut-off of 400 UA/l. Its diagnostic performance (AUC = 0.92, 95% CI, 0.89-0.95) was superior to hs-CRP (AUC = 0.65, 95% CI, 0.60-0.70, P < .001) and faecal calprotectin (fcalpro) (AUC = 0.88, 95% CI, 0.84-0.92, P = .09). Combining the autoantibody with fcalpro further improved diagnostic accuracy (AUC = 0.97, 95% CI, 0.95-0.98) and patient reclassification (P < .001). Autoantibody positivity was associated with a severe phenotype of UC, characterised by increased inflammatory activity and higher IL-17A and granzyme B levels. Higher autoantibody levels were linked to an aggressive disease course, remaining stable in aggressive UC but decreasing in indolent disease (P = .003). Conclusions: Anti-integrin αvβ6 is a reliable diagnostic and prognostic marker for UC, with potential clinical implementation.

Eosinophil Derived Neurotoxin (EDN) is an eosinophil granule protein that is released during eosinophil activation. EDN has proven to be a promising marker for eosinophilic inflammation both in asthma and in wheezing symptoms in children. Here we present a novel ImmunoCAPTM automated immunofluorescence research assay for measurement of EDN and its potential use in diagnosis of asthmatic children. We report the analytical performance of the assay in serum, heparin- and EDTA-plasma in terms of precision, linearity, sensitivity, interfering substances and specimen handling. We also compared the EDN research assay with established methods for asthma diagnosis: fraction of exhaled nitric oxide (FeNO) and blood eosinophil fraction (EOS%) to demonstrate the diagnostic value of EDN in childhood asthma. The total precision (measured using percentage CV) was ≤5.8% for both serum and plasma. The dilution analysis yielded linear results across the dynamic range of the assay for both serum and plasma. No notable interferences of endogenous substances were observed.The median concentration of EDN was significantly higher in the asthma group compared to the healthy controls and the EDN correlates well with EOS%. we have shown that EDN can be measured reliably and robustly with the ImmunoCAP platform in both serum and plasma samples. EDN can be used to distinguish asthmatic from healthy children and correlates well with EOS% and could be a valuable complement to both EOS% and FeNO.

INTRODUCTION: Neutrophilic calprotectin (CP) and myeloperoxidase (MPO), neutrophil gelatinase-associated lipocalin (NGAL), and eosinophil-derived neurotoxin (EDN) are suggested proxy markers for gut inflammation. However, there are insufficient supporting data for MPO, NGAL, and EDN. METHODS: In a cross-sectional investigation including adult patients, we studied the ability of CP, MPO, NGAL, and EDN, measured in fecal and serum samples, to differentiate between inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), and to predict disease activity. RESULTS: Fifty-nine patients had ulcerative colitis (UC), 38 had Crohn's disease, and 100 patients had IBS. The protein concentrations were higher in patients with IBD in the fecal samples (P < 0.001) and the serum samples (P < 0.01), and they correlated weakly (r_s ≤0.38) between the sample sources. Fecal EDN was higher in patients with Crohn's disease compared with UC (1.79 vs 0.50 mg/kg, P = 0.016). The neutrophilic proteins were superior to EDN in the fecal samples for differentiating between patients with IBD and IBS. Fecal MPO (cutoff: 0.86 mg/kg) had the highest sensitivity (74.7%) and specificity (84.6%). Combining fecal CP and MPO increased the sensitivity to 82.3% (specificity: 73.6%). NGAL (cutoff: 196.9 μg/L) showed the best discriminating performance in serum (sensitivity: 62.9%; specificity: 68.0%). Serum NGAL (cutoff: 272.4 μg/L) predicted active disease in UC (Partial Mayo Score ≥2) with a sensitivity and specificity of 57.1% and 83.3%, respectively. DISCUSSION: Fecal MPO and serum NGAL are promising novel biomarkers, in addition to fecal CP, for differentiating between IBD and IBS. Serum NGAL may also predict disease activity in patients with UC.