Complement 5a galvanizes immune inflammation in Hunter syndrome

Abstract

Abstract Hunter syndrome, is a lysosomal storage disease (LSD) caused by mutation in IDS that elicits deficiency of iduronate-2-sulfatase. IDS defect initiates excess storage of glycosaminoglycans (GAGs), i.e., heparan sulfate (HS) and dermatan sulfate (DS) in almost every cell of different organs, (e.g., liver, spleen, lung, heart, bones, skin, brain, and nervous system). Affected individuals exhibit abnormal appearance, mental development, organ function, physical skills and death at the age of 10–20 years. Mechanism by which such GAGs propagate disease in Hunter syndrome is wanted. We directly compared inflammatory responses to DS in different groups of BALB/c mice by injecting (i.p./day for 4 weeks) them separately with altered doses of DS, (0, 1, 2, 4, and 8 mg). Complement 5a (C5a) and their receptor (C5aR1) were measured in mice sera and monocytes. As compared to vehicle (PBS), DS treated mice sera and monocytes showed dose dependent increases of C5a and C5aR1. Human patients with Hunter syndrome also showed elevated serum level of C5a when compared to healthy controls. C5a-C5aR1 axis has been valued for increased staffing of immune cells and their venomous influence on tissue impairment in LSD and non LSDs. To explore this risk in Hunter syndrome, mice were injected in presence or absence of indicated amounts of DS and circulatory subsets of immune cells were measured. As compared to vehicle, DS treated mice showed dose dependent rises of monocytes, eosinophils, and neutrophils and their link to excess generation of pro-inflammatory cytokines. Our data showed that DS-induced C5a-C5aR1 axis wave the immune inflammation, which is fatal in Hunter syndrome. Targeting C5a/C5aR1 axis could be potential alternative therapy of Hunter syndrome.