Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level

Undergraduate

Department

Animal Science

Advisor/Mentor

Erf, Gisela

Committee Member

Orlowski, Sara

Second Committee Member

Rogers, Lauren

Abstract

Intradermal injections of silicone materials have resulted in chronic inflammation and fibrotic reactions in some individuals. The UCD200/206 line of chickens is characterized by spontaneous development of scleroderma/systemic sclerosis (SSc), a fibrotic autoimmune disease. This longitudinal study examined the cellular inflammatory activity initiated by SILIKON 1000 (a silicone product used as a filler in human skin) at the site of intradermal (i.d.) injection and in the peripheral blood in the SSc-prone UCD 200/206 (UCD) chickens and healthy White Leghorn (WL) controls. Specifically, the pulps of growing feathers (GFs) were i.d. injected with SILIKON or endotoxin-free, sterile PBS (8 and 3 birds/line, respectively; 10 µL/GF; 20 GF/bird). Three GFs and heparinized blood were collected before (0 d) and at 0.25 (6 h), 1, 2, 3, and 7 d post-injection (p.i.) to determine immune cell profiles by immunofluorescent staining of pulp- and blood-cell suspensions and cell population analysis by fluorescence-based flow cytometry. GF-pulp injection of SILIKON resulted in similar, rapid (6 h) heterophil and macrophage increases in GF-pulps in both lines, with higher macrophage levels (% pulp cells) at 6 h in UCD than WL. While GF-pulp lymphocyte levels did not change post SILIKON injection in both lines, levels were higher in WL than in UCD at 1 d p.i. In the blood, concentrations (103 cells/μL) of heterophils, monocytes, and lymphocytes did not change significantly over time, but heterophil and monocyte concentrations were higher in UCD at 2 d and at 6 h and 7 d p.i., respectively. Examination of lymphocyte subsets revealed similarly elevated levels of B cells and CD4+ T cells in GF-pulps of both lines. In the blood, B cell concentrations increased similarly in both lines, reaching peak levels at 2 d p.i. Concentrations of CD4+, CD8+, or γδ T cells did not change post GF-pulp SILIKON injection in UCD, but in WL there was a shift in the proportions among CD4+ T cells and γδ T cells, with increased and decreased concentrations from 1 to 7 d, respectively. Comparisons of the effects of SILIKON 1000 and PBS injections revealed that SILIKON resulted in higher monocyte/macrophage and γδ T cell recruitment into GF-pulps of WL chickens, and in higher recruitment of total lymphocytes, especially CD4+ T cells, into GF-pulps of SSc-prone UCD chickens. These observations, together with the greater levels of monocytes/macrophages in SILIKON injected GF-pulps and blood of UCD chickens, highlight the qualitative differences in the inflammatory responses initiated by SILIKON in SSc-prone UCD and healthy WL chickens. It appears that the inflammatory response in the SSc-prone UCD 200/206 chickens may be heading towards collagen production and fibrosis development. More research is needed to determine the functional activities of the immune cells recruited to the site of SILIKON 1000 injection.

Keywords

silicone injections; SILIKON 1000; scleroderma/systemic sclerosis; UCD 200/206 chickens; inflammatory response; immune cell profiles

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