Characterization of serum anyloid P and Fc gamma receptor: A critical engagement implicated in fibrosing diseases

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dc.contributor.advisorGomer, Richard H.
dc.creatorCrawford, Jeffrey Ray
dc.date.accessioned2013-03-08T00:33:12Z
dc.date.available2013-03-08T00:33:12Z
dc.date.issued2012
dc.description.abstractFibrotic diseases have a poor prognosis with no FDA approved therapies. Monocyte-derived, fibroblast-like cells called fibrocytes participate in the formation of fibrotic lesions. The conserved pentraxin protein serum amyloid P (SAP) inhibits fibrocyte differentiation in cell culture, and injections of SAP significantly reduce fibrosis in several animal models. SAP binds to the receptors for the Fc portion of immunoglobulin G (FcγR), and has been crystallized bound to FcγRIIa. The in vivo activity of SAP appears to be dependent on the common γ chain (FcγR) of activating Fc receptors. The goal of my project is to elucidate the functional domains of SAP and the receptor responsible for SAP bioactivity, which could lead to refinements for SAP as a therapeutic agent and additional drug targets. I found that mutagenesis of the residues critical for SAP binding to FcγRIIa only moderately decreases SAP's ability to inhibit fibrocyte differentiation. In murine cells, deletion of FcγR or FcγRI significantly reduced sensitivity to SAP. Deletion of the combination of FcγRIIb/FcγRIIIa/FcγRIV did not significantly affect sensitivity to SAP, while deletion of just the inhibitory receptor FcγRIIb increased sensitivity to SAP. In human cells, siRNA-mediated reduction of FcγR or FcγRI levels significantly decreased sensitivity to SAP, while reduction of FcγRIIb levels increased sensitivity to SAP. These observations suggest that SAP, at least in part, uses FcγRI and FcγR to inhibit fibrocyte differentiation. I am also interested in how SAP functions in various disease states. SAP is known to be elevated in Alzheimer's disease (AD) and binds to amyloid plaques in the brain, a key hallmark of AD. There is a significant population of individuals that have key hallmarks of AD but show no signs of cognitive impairment, termed non-demented with AD neuropathology (NDAN). I evaluated SAP levels in post mortem samples of hippocampus and frontal cortex in age-matched controls, AD, and NDAN individuals. AD individuals had significantly increased SAP levels, while NDAN samples had no significant difference in SAP levels compared to controls. These results suggest that low levels of SAP in plaques marks the brains of individuals that escape dementia despite the presence of beta amyloid plaques.
dc.format.extent181 p.en_US
dc.format.mimetypeapplication/pdf
dc.identifier.callnoTHESIS BIOENG. 2012 CRAWFORD
dc.identifier.citationCrawford, Jeffrey Ray. "Characterization of serum anyloid P and Fc gamma receptor: A critical engagement implicated in fibrosing diseases." (2012) Diss., Rice University. <a href="https://hdl.handle.net/1911/70222">https://hdl.handle.net/1911/70222</a>.
dc.identifier.digitalCrawfordJen_US
dc.identifier.urihttps://hdl.handle.net/1911/70222
dc.language.isoeng
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.
dc.subjectHealth sciences
dc.subjectEnvironmental science
dc.subjectBiological sciences
dc.subjectSerum anyloid P
dc.subjectFc gamma receptors
dc.subjectAlzhemer's disease
dc.subjectFibrosing diseases
dc.subjectFibrocyte
dc.subjectCellular biology
dc.subjectImmunology
dc.titleCharacterization of serum anyloid P and Fc gamma receptor: A critical engagement implicated in fibrosing diseases
dc.typeThesis
dc.type.materialText
thesis.degree.departmentBioengineering
thesis.degree.disciplineEngineering
thesis.degree.grantorRice University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy
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