UVM Theses and Dissertations
Format:
Print
Author:
Maneen, Matthew
Dept./Program:
Anatomy and Neurobiology
Year:
2005
Degree:
MS
Abstract:
The chemokine, stromal cell derived factor (SDF), is expressed in macrophages, Schwann cells, astrocytes, microglia, and specific neuronal populations, and can chemoattract leukocytes to a variety of tissue types (Blades, Ingegnoli et al., 2002. Arthritis Rheum, 46(3): 824-36.). Due to its expression patterns, SDF and its receptor CXCR4 may function in the inflammatory response of nerve injury, facilitating repair of the adult peripheral nervous system (PNS). The goal of this study was to determine whether SDF functions in sciatic nerve crush and transection injury and repair. First, SDF and CXCR4 expression was characterized in the injured sciatic nerve, followed by characterization of leukocyte infiltration in response to SDF application, and finally a CXCR4 blocking agent (intrakine) was produced and tested. It is our hypothesis that SDF functions in nerve injury to attract specific inflammatory cells, which can induce intrinsic repair mechanisms. These mechanisms may lead to the clearing of myelin and cellular debris, facilitating axonal regeneration. The following studies were designed to evaluate the roles of CXCR4 and SDF in nerve injury and repair in the adult.
The data obtained showed that SDF is released and expression in crushed and transected sciatic nerve was regulated following injury. Additionally, SDF was capable of chemoattracting leukocytes to a lesion site. It is also clear that an increase in SDF resulted in significant changes in numbers and types of infiltrating cells. Our data suggests that SDF may playa role in repair of the PNS following injury. Additionally, a KDEL intrakine (Chen JD, et al., 1997. Nat Med., 3(10):1110-6) capable of interfering with membrane expression of the SDF receptor was produced and tested for functionality through various bioassays. The intrakine was capable of downregulating cell surface CXCR4 expression, effectively blocking the cell's ability to bind SDF. This system can be incorporated into an inducible, in vivo Tetracycline regulated system, allowing the study of PNS injury and repair in the absence of SDF function. We have characterized the regulation of SDF and CXCR4 in the injured PNS, characterized the types and numbers of SDF induced leukocyte infiltration, and developed an in vivo approach to blocking SDF signaling.
The data obtained showed that SDF is released and expression in crushed and transected sciatic nerve was regulated following injury. Additionally, SDF was capable of chemoattracting leukocytes to a lesion site. It is also clear that an increase in SDF resulted in significant changes in numbers and types of infiltrating cells. Our data suggests that SDF may playa role in repair of the PNS following injury. Additionally, a KDEL intrakine (Chen JD, et al., 1997. Nat Med., 3(10):1110-6) capable of interfering with membrane expression of the SDF receptor was produced and tested for functionality through various bioassays. The intrakine was capable of downregulating cell surface CXCR4 expression, effectively blocking the cell's ability to bind SDF. This system can be incorporated into an inducible, in vivo Tetracycline regulated system, allowing the study of PNS injury and repair in the absence of SDF function. We have characterized the regulation of SDF and CXCR4 in the injured PNS, characterized the types and numbers of SDF induced leukocyte infiltration, and developed an in vivo approach to blocking SDF signaling.