Figure 6.

Inhibition of CXCL8/IL-8 production by CAMP1-derived peptides in vitro. (A–C) HaCaT cells were treated with A14, A15, B1, B2, B3, C1 and C3 peptides at a concentration of 3.9 to 250 μM or with A14, B1, B2 peptides (62.5 μM) for 24 h and were then stimulated with C. acnes (MOI 15) for 18 h. The negative control consists of untreated and unstimulated cells (HaCaT alone). The positive control corresponds to cells stimulated with C. acnes (HaCaT + C. acnes). (D) Cytotoxicity was assessed in the MTT assay. (A,D) Dimethy sulfoxide (DMSO) corresponds to the control experiment with a solution of DMSO/H₂O 30:70 (v/v) used to solubilize the peptides A14 and A15. (E) HaCaT cells were stimulated with various concentrations of nmrCAMP1 (0.01 to 20 μg/mL). The positive control corresponds to cells stimulated with PGN (5 μg/mL). (F,G) HaCaT cells were stimulated with nmrCAMP1 and mrCAMP1 (10 μg/mL). The positive control corresponds to cells stimulated with PGN (5 μg/mL). (H) Primary normal human epidermal keratinocyte cells (NHEK) were treated with A14, B1 and B2 peptides at a concentration of 62.5 μM for 24 h at 37 °C and stimulated with nmrCAMP1 (10 μg/mL) for 18 h. The negative control was the untreated and unstimulated cells (NHEK alone). The positive control corresponds to cells stimulated with nmrCAMP1 (NHEK + nmrCAMP1). (B,F) The level of CXCL8/IL-8 mRNA was assessed by qRT-PCR. (A,C,E,G,H) CXCL8/IL-8 production was assessed by ELISA. Statistical significance is indicated by * (p < 0.05), ** (p < 0.01), *** (p < 0.001) and **** (p < 0.0001).