Reduction of senescence-associated secretory phenotype and exosome-shuttled miRNAs by Haritaki fruit extract in senescent dermal fibroblasts.

OBJECTIVE

Skin ageing is linked to the accumulation of senescent cells and a "senescence-associated secretory phenotype" (SASP). SASP factors include chemokines, cytokines, and small extracellular vesicles (EVs) containing miRNAs. We characterized SASP profile markers in normal human dermal fibroblasts (HDFs) and evaluated the effect of Haritaki fruit extract on these senescence markers.

METHODS

Senescence was induced in HDFs by ionizing radiation (X ray), followed by 14 days of culture. Parallel incubations included fibroblasts treated for 12 days with 10 or 100 μg/mL Haritaki (a standardized extract of Terminalia chebula fruit). Senescence was assessed on Day 14 according to cell morphology, β-galactosidase activity, RT-qPCR measurement of SASP genes, as well as semi-quantitative (RT-qPCR) expression of miRNAs contained in EVs isolated from the medium. The size and distribution of EVs were measured by Nanoparticle Tracking Analysis.

RESULTS

Human dermal fibroblasts exhibited a senescent phenotype 14 days after ionizing-radiation, demonstrated by a flattened and irregular shape, increased β-galactosidase activity and over-expression of SASP genes. CSF3, CXCL1, IL1β, IL6 and IL8 genes were increased by 1492%, 1041%, 343%, 478%, 2960% and 293%, respectively. The cell cycle inhibitor, CDKN1A, was increased by 357%, while COL1A1, was decreased by 56% and MMP1 was increased by 293%. NTA analysis of the EVs size distribution indicated a mix of exosomes (45-100 nm) and microvesicles (100-405 nm). miRNA expression in EVs was increased in senescent fibroblasts. miR 29a-3p, miR 30a-3p, miR 34a-5p, miR 24a-3p and miR 186-5p were increased in senescent HDF by 4.17-, 2.43-, 1.17-, 2.01, 12.5-fold, respectively. Incubation of senescent fibroblasts with Haritaki extract strongly decreased SASP mRNA levels and miRNA expression in EVs.

CONCLUSION

Haritaki strongly reduced SASP expression and EV-shuttled miRNAs in senescent fibroblasts. These results indicate that Haritaki has strong senomorphic properties and may be a promising ingredient for the development of new anti-ageing dermo-cosmetic products by inhibiting deleterious effects of senescent cells.