Reduced levels of interleukin 33 and increased levels of soluble ST2 in subjects with amyotrophic lateral sclerosis

Abstract

Interleukin 33 (IL-33) is a cytokine that functions as an alarmin and is released from damaged tissue. The receptor for IL-33 is ST2, which exists as membrane bound and soluble forms. Levels of IL-33 and soluble ST2 (sST2) are elevated in some inflammatory diseases. Amyotrophic lateral sclerosis (ALS) is a disease that is due to loss of motor neurones, with some neuro-inflammation at the site of pathology. This study was performed to measure levels of IL-33 and sST2 in ALS. Serum was obtained from subjects with ALS (n=42) and healthy controls (n=38). Levels of IL-33 and s ST2 were measured with ELISA. The level of Il-33 was significantly lower in ALS subjects than healthy controls, and the levels of sST2 were significantly higher. The lower levels of IL-33 could be due to degradation of IL-33 by caspases released from apoptotic cells. However the levels of IL-33 could also be lower due to effects of sST2 which acts as a receptor for IL-33. The levels of sST2 could reflect inflammation in ALS.