Graduation Date
5-2013
Document Type
Master's Thesis
Degree Name
Master of Science
Department or Program
Biological Sciences
Department or Program Chair
Kiowa Bower, Ph.D.
First Reader
Michael Ward, PhD
Second Reader
Mary B. Sevigny, PhD
Abstract
Mucopolysaccharidoses is a family of metabolic disorders caused by the absence or irregular functioning of lysosomal enzymes required to degrade glycosaminoglycans. Mucopolysaccharidosis IVA (MPS IVA or Morquio A syndrome) is characterized by the functional loss of the enzyme N-‐acetylgalactosamine-‐6-‐ sulfatase (GALNS). The absence of GALNS leads to the chronic accumulation of the glycosaminoglycans keratan sulfate (KS) and possibly chondroitin-‐6 sulfate (C6S). KS accumulation occurs in the lysosomes of KS-‐rich tissues such as cartilage, cornea, and heart valve as well as some specific cell types such as macrophages. This suggests that MPS IVA is a systemic disease that may disrupt cellular homeostasis throughout the body. Recent work on mucopolysaccharidoses and KS has produced two opposing models to explain the repercussions of KS accumulation. Although both theories implicate a dysregulation of immune functioning, specifically in regards to inflammatory response, one theory assumes that KS is (like other GAGs) in that it is pro-‐inflammatory while the other theory suggests that it is anti-‐inflammatory. In this study, two macrophage cell lines— the human acute monocytic leukemia cell line THP-‐1 and human monocyte-‐derived macrophages (MDMs))— are used to investigate the roll of KS in inflammatory response. Initial findings suggest that human macrophages respond to KS at pathological but not physiological levels. Unlike chondroitin sulfate (CS) and lipopolysaccharide (LPS), elevated levels of KS suppress NFkB activation and do not induce a significant release of inflammatory factors. Though KS does not affect cell viability or promote apoptosis, it does inhibit 7 mitochondrial metabolic activity and the proliferation/differentiation rate of MDMs. These results indicate that, unlike CS, KS does not appear to induce an increase of inflammatory response in human macrophages. In fact, KS may modulate inflammatory response in an immunosuppressive manner thereby suppressing the immune system of Morquio A patients.