An observational study demonstrating the measurement, characterization and validation of expression of calprotectin in human sweat through a sweat wearable

Abstract

Inflammatory bowel diseases (IBD) comprising Crohn's disease (CD) and ulcerative colitis (UC) are typically characterized by chronic episodes of inflammation within and through the gastrointestinal (GI) tract. Calprotectin (CP) is a biomarker employed by clinicians effectively guide diagnostic and therapeutic decisions. However, there exists several challenges in sample collection and fecal CP testing for patient-use and patient enablement. Hence, there is a current unmet need to access CP in a completely non-invasive manner. This work is the first demonstration of CP in sweat using a wearable sweat sensor device. The sweat sensor device demonstrated a wide dynamic range of 0.1–10 μg/mL with a limit of detection of 0.1 μg/mL. The sensor was also specific to CP and demonstrated negligible to no response for non-specific inflammatory markers such as C-reactive protein, interleukin-6. Excellent correlation was achieved between ELISA and the sweat sensor device with Pearson's r > 0.95. Human subject studies demonstrated that elevated basal levels in IBD subject (500 ng/mL) as compared to healthy cohort (∼350 ng/mL). Further, 3 times increase in CP levels was observed due to flare-up in the IBD subject with a mean concentration ∼1300 ng/mL as compared to the basal levels. The pre-clinical results of elevated CP levels will be of significant interest to clinicians as it provides a non-invasive and non-intrusive tracking flare-ups in IBD patients and can aid in better management of the disease.