Serum IL-17A levels in patients with UC reflect severity, predict disease course

ORLANDO, Fla. — Serum levels of IL-17A were reflective of disease severity and predictive of clinical and biochemical disease course among patients with ulcerative colitis in a study presented at Digestive Disease Week.

Researchers prospectively monitored 99 treatment-naive patients (median age, 32 years; 72% men) with ulcerative colitis (UC) from disease onset through 3 years of follow-up, They assessed disease severity annually via fecal calprotectin levels, Mayo score and flares. Blood and stool samples were collected at baseline and at each visit, and rectal biopsy was performed at baseline. Mucosal and serum RNA cytokine levels were measured and compared against those of 10 healthy controls.

IL-17A expression was nearly 100 times greater in the mucosal mRNA of patients with UC than controls. Interferon gamma and IL-13 also were elevated in the UC group, 12.4 times and 6.7 times, respectively, as was expression of cytokines IL-8 (38 times) and IL-6 (12.7 times). No significant associations, however, were observed between disease severity and mucosal expression of any assessed cytokines.

Investigators noted a correlation between serum IL-17A and Mayo score at disease onset (P=.0013), which remained significant after Bonferroni correction for multiple testing (P=.017). Serum levels of IL-17A at disease onset were predictive of disease course; both clinically, as indicated by flare severity and number in the previous year (P=.0013; P=.0017 after Bonferroni adjustment) and biochemically, as indicated by fecal calprotectin levels collected at each follow-up (P=.0059; P=.05 after Bonferroni correction). No other associations between UC severity and serum or mucosal cytokines were observed.

“We have demonstrated that, in newly diagnosed, treatment-naive UC patients, there is a strong up-regulation of mucosal IL-17A,” researcher Lena Ohman, PhD, department of microbiology and immunology at Sahlgrenska Academy in Gothenburg, Sweden, said. “Also, at the time of diagnosis, serum IL-17A level is associated with disease severity, and serum IL-17A seems to predict future disease course in this patient cohort. Therefore, we conclude that serum IL-17A at diagnosis of disease may be used as a biomarker to predict the future disease course.”

Disclosure: The researchers reported numerous financial disclosures.

For more information:

Ohman L. #155: Serum IL-17A in Newly Diagnosed Treatment-Naive Ulcerative Colitis Patients Reflects Disease Severity and Predicts the Course of Disease. Presented at: Digestive Disease Week 2013; May 18-21, Orlando, Fla.