## 3 Results
### Cytokine Expression  
The results for the different pro-inflammatory ILs, expressed at mRNA level from HaCaT cells in contact with the scaffolds as well as pure OLE after 6 and 24 h, are reported in Figures 4-7. OLE alone was administrated to the cells in standard culture (namely, without fibers) using the same dose loaded in 1 cm\({}^{2}\) of fibers. Figure 4 shows the expression of IL-1 (\(\alpha\) and \(\beta\) isoforms) by HaCaT cells in contact with the different PHA fibers and with OLE up to 24 h. Comparing to the basal expression conditions of HaCaT cells, both IL-1\(\alpha\) and IL-1\(\beta\) expressions were significantly downregulated by all the fibers in 6 h, independently of OLE incorporation. OLE alone was able to modulate IL-1\(\alpha\) and IL-1\(\beta\) expression in 24 h, showing statistical significance in IL-1\(\beta\) (\(p<0.05\)). The specific action of OLE in long term (24 h) downregulation of IL-1\(\beta\) was observed in OLE/P(PHB/PHOHD) fibers (\(p<0.05\)). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sample** & **PHBHV** & **OLE/PHBHV** & **PHB/PHOHD** & **OLE/(PHB/PHOHD)** & **Plain OLE** \\  & **Fibers** & **Fibers** & **Fibers** & **Fibers** & **Fibers** \\ \hline
**\%ABred** & 74\% & 77\% & 76\% & 75\% & 94\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results of metabolic activity (AlamarBlue test). Data are given as average (\(n=2\)). Figure 3: Graph showing the cumulative release (\(w/w\)%) of the three main OLE polyphenols from PHBHV/OLE fiber meshes during 24 h. The released quantities after 6 h reached 90% (\(w/w\)%) for oleuropein, and 80% (\(w/w\)%) for luteolin-7-O-glucose and apigenin-7-O-glucose. The highest release is observed for all polyphenols during the first 30 min. Differently, plain PHBHV fibers maintained a significantly reduced expression over time (\(p<0.01\)). Figure 4: Bar graphs showing IL-1 expression by HaCaT cells at 6 and 24 h: IL-1\(\alpha\), and IL-1\(\beta\). Comparisons between samples were analyzed by Student’s \(t\)-test. Data are mean \(\pm\) SD and are expressed as percentage of increment relative to untreated cells (used as controls). Significant differences are indicated by * (\(p<0.05\)), differences are indicated by * (\(p<0.01\)) and * (\(p<0.001\)) for comparison between each sample and its respective control. Figure 5: Bar graph showing IL-6 expression by HaCaT cells at 6 and 24 h. Comparisons between samples were analyzed by Student’s \(t\)-test. Data are mean \(\pm\) SD and are expressed as percentage of increment relative to untreated cells (used as controls). Significant differences are indicated by * (\(p<0.05\)), ** (\(p<0.01\)) and * (\(p<0.001\)) for comparison between each sample and its respective control. Figure 6: Bar graph showing IL-8 expression by HaCaT cells at 6 and 24 h. Comparisons between samples were analyzed by Student’s \(t\)-test. Data are mean \(\pm\) SD and are expressed as percentage of increment relative to untreated cells (used as controls). Significant differences are indicated by * (\(p<0.05\)), ** (\(p<0.01\)) and * (\(p<0.001\)) for comparison between each sample and its respective control. The expression of IL-6 is displayed in Figure 5. IL-6 resulted to be strongly downregulated by all the PHA fiber formulations with statistical significance (all \(p<0.05\)). OLE alone did not significantly changed the IL-6 expression level at 6 and 24 h with respect to the basal expression level of HaCaT cells (\(p\) = n.s.). A specific effect of OLE incorporation in the fibers could not be revealed for IL-6 expression. The outcomes of IL-8 expression are reported in Figure 6. Moreover, in this case, a strong downregulation of this cytokine was exerted by all the fibers independently of OLE incorporation (all \(p<0.05\)). Differently, OLE alone caused a marked upregulation after 6 h (\(p<0.05\)), which was still significant after 24 h (\(p<0.01\)).