OBJECTIVETo investigate the effect of oleic acid on the proliferation and secretion of pro-inflammatory mediators of human normal fibroblasts and scar fibroblasts.

METHODSHuman normal fibroblasts and scar fibroblasts were cultured in vitro and respectively divided into seven groups according to the random number table, with 8 samples in each group. Cells in blank control (BC) group were routinely cultured without addition of other agents. Cells in ethanol-control (EC) group were cultured with medium with the addition of 2% absolute ethanol. Cells in oleic acid groups were cultured with the addition of oleic acid in concentration of 0.25, 0.50, 1.00, 2.00, or 4.00 mmol/L in 2% absolute ethanol. The growth of cells in each group was observed with trypan blue staining on post culture day (PCD) 1-5. On PCD 2, structure of cells in BC, EC, and 1.00 mmol/L oleic acid groups was observed under inverted phase contrast microscope and transmission electron microscope; cell cycle of BC, EC, and 1.00 mmol/L oleic acid groups was measured by flow cytometer; cell proliferation activity in each group was measured by MTT assay; the level of NO in supernatant was assayed by Griess assay; the levels of TNF-α, IL-1β, IL-6, and IL-8 in supernatants in each group were determined by enzyme-linked immunosorbent assay. Data were processed with multifactor and repeated measurement design analysis of variance.

RESULTS(1) There was no significant difference in each index of normal fibroblasts and scar fibroblasts between BC group and EC group. (2) The numbers of normal fibroblasts and scar fibroblasts in 2.00 and 4.00 mmol/L oleic acid groups were significantly lower than those in corresponding BC and EC groups on PCD 2-5 (with F values respectively 13.773 and 11.344, P values all below 0.01). (3) On PCD 2, the numbers of normal fibroblasts and scar fibroblasts in 1.00 mmol/L oleic acid groups decreased, and the cells were aggregating, rounding, and easy to drop off. Cellular membrane disruption, vacuolar degeneration of mitochondrion, pyknosis, and lipid droplets were observed. (4) The percentages of G0/G1 and G2/M phases of normal fibroblasts in 1.00 mmol/L oleic acid group [(93.56 ± 9.98)%, (2.01 ± 0.75)%] were significantly higher than those in BC group [(84.23 ± 10.96)%, (0.37 ± 0.16)%, with F values respectively 3.026, 34.751, P < 0.05 or P < 0.01], while the percentage of normal fibroblasts in S phase [(4.42 ± 0.87)%] was markedly lower than that in BC group [(16.06 ± 1.74)%, F = 136.120, P < 0.01]. The percentages of scar fibroblasts of G0/G1 and G2/M phases in 1.00 mmol/L oleic acid group [(93.86 ± 13.90)%, (1.89 ± 0.66)%] were significantly higher than those in BC group [(83.88 ± 10.42)%, (0.41 ± 0.17)%, with F values respectively 3.529, 32.710, P < 0.05 or P < 0.01], and the percentage of scar fibroblasts in S phase [(3.87 ± 0.63)%] was markedly lower than that in BC group [(15.89 ± 2.02)%, F = 116.508, P < 0.01]. (5) The proliferation rates of normal fibroblasts and scar fibroblasts in 0.50-4.00 mmol/L oleic acid groups were significantly lower than those in corresponding BC and EC groups (with F values respectively 215.945 and 194.555, P < 0.05 or P < 0.01). (6) The content of NO in supernatant of normal fibroblasts in all oleic acid groups was obviously higher than that in BC and EC groups (F = 30.240, P < 0.05 or P < 0.01). The contents of NO in supernatants of scar fibroblasts in 1.00-4.00 mmol/L oleic acid groups were significantly higher than that in BC and EC groups (F = 12.495, P < 0.01). The contents of TNF-α and IL-6 in supernatants of normal fibroblasts and scar fibroblasts in 2.00 and 4.00 mmol/L oleic acid groups were obviously higher than those in corresponding BC and EC groups (with F(TNF-α) values respectively 6.911, 3.818, F(IL-6) values respectively 16.939, 11.600,P < 0.05 or P < 0.01). The contents of IL-1β in supernatants of normal fibroblasts and scar fibroblasts in groups of every concentration of oleic acid were significantly higher than those in corresponding BC and EC groups (with F values respectively 25.117, 9.137, P values all below 0.01). The contents of IL-8 in supernatants of normal fibroblasts in 1.00-4.00 mmol/L oleic acid groups were markedly higher than those in BC and EC groups (F = 2.717, P < 0.05 or P < 0.01). The contents of IL-8 in supernatants of scar fibroblasts in 2.00 and 4.00 mmol/L oleic acid groups were significantly higher than those in BC and EC groups (F = 3.338, P < 0.05). There was no statistically significant difference in above indexes between normal fibroblasts and scar fibroblasts in the same concentration of oleic acid group (with F values from 0.120 to 3.766, P values all above 0.05).

CONCLUSIONSAlthough oleic acid in high concentration inhibits the proliferation of scar fibroblasts, it also inhibits the proliferation of normal fibroblasts. Oleic acid in high concentration can cause excessive and continued inflammatory reaction by promoting the secretion of pro-inflammatory mediators of normal fibroblasts and scar fibroblasts, and they are detrimental to wound healing.