| dc.description.abstract | Master thesis, Programme in Medicine. TITLE: Interactions between Staphylococcus epidermidis, monocytes and nano structured gold Surfaces. AUTHOR: Magnus Forsberg. The role of material surface properties for the direct interaction with bacteria and the indirect
route via host defense cells is not fully understood. Recently, nanostructured implant surfaces
were suggested to possess antimicrobial properties. In the present study the adhesion and
biofilm formation of Staphylococcus epidermidis and human monocyte adhesion and
activation were studied separately and in co-culture in different in vitro models by using
smooth (Au) and well defined nanostructured (AuNP) gold model surfaces. Two polystyrene
surfaces were used as controls in the monocyte experiments. Fluorescent viability staining
demonstrated a reduced viability of S. epidermidis close to the nanostructured surface, while
the smooth Au correlated with more live biofilm. The results were supported by scanning
electron microscopy observations, showing higher biofilm tower formations and more mature
biofilms on Au compared to AuNP. Unstimulated monocytes on the different substrates
demonstrated low activation as measured by chemiluminescence, gene expression of pro- and
anti-inflammatory cytokines and cytokine secretion. In contrast, stimulation with opsonized
zymosan or opsonized live S. epidermidis during 1 h, significantly increased the production of
reactive oxygen species, the gene expression of tumor necrosis factor-alpha (TNF-α),
interleukin-1beta (IL-1β), IL-6 and IL-10 and the secretion of TNF-α, demonstrating the
ability of the cells to elicit a response and actively phagocytise the preys when present on all
surfaces. In addition, cells on the smooth Au and AuNP showed a different adhesion pattern
and a more rapid oxidative burst than on polystyrene upon stimulation. It is concluded that S.
epidermidis decreased its viability initially when adhering to nanostructured compared to
smooth gold surfaces, especially in the bacterial cell layers closest to the surface. On the other
hand, material surface properties neither strongly promoted nor attenuated the activity of
monocytes when exposed to zymosan particles or S. epidermidis.
Keywords: nanotopography, staphylococci, host defense, bacteria, zymosan, macrophage | sv |
