Background
Wound healing is a biological process governed by numerous regulatory loops driven by signals from the wound tissue. It is divided into the following overlapping phases: hemostasis and inflammation, proliferation and remodeling. Senescence-associated secretory phenotype (SASP) will express a variety of extracellular modulators, including the most prominent cytokine IL-6 which is known as one of pro-inflammatory cytokines that contribute to chronic wounds. Capsaicin (CAP) has been known to decrease pro-inflammatory cytokines (e.g., IL-6) and increase an anti-inflammatory cytokine (e.g., IL-10), on the other hand, CAP may have the effect of promoting wound healing. In this study, we aim to analyze the effects of CAP on antiinflammation in association to different activities of skin fibroblasts (Hs68).

Methods
In vitro cell model was applied to analyze the effects of CAP on wound healing in association to different passages of Hs68. We used different passages to indicate senescent states for the HS68 cells: low passages (P24), representing active state; high passages (P42, the highest passage for HS68 cells suggested by BCRC), representing inactive state. The senescence, cell viability, migration and inflammation were revealed from skin fibroblast with or without CAP (10μM) treatment. Gene quantitation were performed from HS68 cells of low passages and high passages, which were treated with TNF-α and 10μM CAP for 24 hours.

Results
Relative quantitation of the SA-β-gal-positive cells of low passages and high passages of HS68 cells were measured which revealed high passages group are two times higher than low passages group (P<0.001).
Cell viability was assessed in low passages and high passages. There was no significance difference between the control group and those with 10μM CAP.
Migration assessment of HS68 cells for low passages and high passages under different CAP concentration. The cell migration rate decreased in the presence of pro-inflommatory cytokine (e.g., TNF-α), while it getting higher under 10μM CAP (P<0.05). The relative mRNA level of IL-6 dropped under the presence of 10μM CAP in low passages (P<0.01). On the other hand, the relative mRNA level of IL-6 elevated in high passages (P<0.001).

Conclusion
In this study, low-dose Capsaicin is responded to decrease inflammatory factors in Hs68 and has different effects on Hs68 of different passages.

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