Semester

Spring

Date of Graduation

2003

Document Type

Dissertation

Degree Type

PhD

College

School of Medicine

Department

Microbiology, Immunology, and Cell Biology

Committee Chair

John B. Barnett.

Abstract

Propanil has been shown to induce numerous manifestations of impaired immune responses. This dissertation focuses on the effects of propanil on TNF-alpha production and NFB activation in murine and human macrophages in response to LPS stimulation. Initial studies demonstrated that propanil treatment of the murine peritoneal macrophage cell line, IC-21 resulted in decreased NF-kappaB activation and transcriptional activity as determined by Western blot and NF-kappaB-dependent reporter gene transcription, respectively. Nuclear localization of NF-kappaB was also shown to be decreased by immunofluorescence. Additional studies to confirm these effects in the human cell line, THP-1 also showed decreased nuclear levels of NF-kappaB in propanil-treated cells. Additionally, NF-kappaB levels were determined from peritoneal exudate cells (PEC) harvested from mice treated with 200mg/kg propanil in vivo, and shown to be decreased compared to the corn oil (vehicle) control. However, analysis of the inhibitor of NF-kappaB, IkappaBalpha, demonstrated no differences in its degradation between propanil-treated and ethanol (vehicle) control cells in THP-1 cells. Therefore, propanil alters nuclear localization of NF-kappaB independently of degradation of IkappaBalpha.;Effects of propanil on macrophage functions were also evaluated. Propanil reduced phagocytic abilities of macrophages, as determined by phagocytosis of 2 mum fluorescent spheres. Additionally, propanil abrogated the phorbol ester-induced NADPH oxidase activity of PEC and THP-1 cells. Listericidal ability of PEC and THP-1 cells were also evaluated following propanil treatment. Results indicated that propanil treatment significantly reduced the ability of activated macrophages to kill intracellular Listeria monocytogenes . Because bacterial killing is dependent on superoxide production, the decreased listericidal capabilities of propanil-treated macrophages was expected.;The data presented herein extend our knowledge of propanil's immunotoxic effects, and begin to mechanistically dissect the effects of propanil on specific signal transduction pathways. In light of the reduction of TNF-alpha production, NF-kappaB and respiratory burst activity of macrophages, however, this study also demonstrates a possible beneficial role for propanil as a potent anti-inflammatory compound.

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