Abstract

Senescent cells display an increase in the secretion of growth factors, inflammatory cytokines and proteolytic enzymes, termed the “senescence-associated-secretory-phenotype” (SASP), playing a major role in many age-related diseases. The phenolic compounds present in extra-virgin olive oil are inhibitors of oxidative damage and have been reported to play a protective role in inflammation-related diseases. Particularly, hydroxytyrosol and oleuropein are the most abundant and more extensively studied. Pre-senescent human lung (MRC5) and neonatal human dermal (NHDF) fibroblasts were used as cellular model to evaluate the effect of chronic (4–6 weeks) treatment with 1 μM hydroxytyrosol (HT) or 10 μM oleuropein aglycone (OLE) on senescence/inflammation markers. Both phenols were effective in reducing β-galactosidase-positive cell number and p16 protein expression. In addition, senescence/inflammation markers such as IL-6 and metalloprotease secretion, and Ciclooxigenase type 2 (COX-2) and α-smooth-actin levels were reduced by phenol treatments. In NHDF, COX-2 expression, Nuclear Factor κ-light-chain-enhancer of activated B cells (NFκB) protein level and nuclear localization were augmented with culture senescence and decreased by OLE and HT treatment. Furthermore, the inflammatory effect of Tumor Necrosis Factor α (TNFα) exposure was almost completely abolished in OLE- and HT-pre-treated NHDF. Thus, the modulation of the senescence-associated inflammatory phenotype might be an important mechanism underlying the beneficial effects of olive oil phenols.

Highlights

  • Cellular senescence is characterized by complex modifications in the protein expression profile of the cell, leading to replicative arrest and cell dysfunction [1]

  • Senescent cells are characterized by a strong increase in the secretion of growth factors, inflammatory cytokines, and proteolytic enzymes, termed the “senescence-associated secretory phenotype” (SASP), that has been thoroughly described in cultured fibroblasts [2]

  • The SASP is thought to play a major role in many age-related diseases, such as Alzheimer’s disease [3], cancer [4], where it contributes to the maintenance of a chronic inflammation which is typical of this pathology [5], and endothelial dysfunction in cardiovascular diseases and type 2 diabetes, characterized by a low-grade chronic inflammation state [6]

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Summary

Introduction

Cellular senescence is characterized by complex modifications in the protein expression profile of the cell, leading to replicative arrest and cell dysfunction [1]. Twheeekpsa)rtarmeaettmeresnat swseitshseodlivine porhdeenroltsooenvaselunaetsecesnecneesdceevnecleopwmeerne:t tihseshtootwalnninumFibgeurreof2.ceTlhlse cpoalrleacmteedtearsnadssceosusnedtedinaotrdtheer teondevoaflutahtee tsreenaetmsceennct,etwheerpee: rtcheenttoatgael nouf mcebllesr of cells collected and counted at the end of the treatment, the percentage of cells positive to SA-βgal staining, and the level of p16 protein expression Both hydroxytyrosol (HT) and oleuropein aglycone (OLE) brought about a significant increment in cell number, while SA-βgal staining and p16 protein. In a sub-group of experiments we aimed at evaluating the effect of the treatment with OLE and HT on externally-induced inflammation, using a 3 h Tumor Necrosis Factor α (TNFα) stimulation. Sscui.b2-0g17r,o1u8p, 22o7f5experiments we aimed at evaluating the effect of the treatment with OLE6 aofn1d3 HT on externally-induced inflammation, using a 3 h Tumor Necrosis Factor α (TNFα) stimulation iinn hhiigghh PPDDLL ((oolldd)) NNHHDDFF. TfloutoarlesNceFnκcBe finluteonresistcye(nbc)eainndteMnsaintyde(rb’)s caonedffiMcieanntd(eMr’1s)c(oc)e,fufisceiedntto(aMss1e)ss(cN),FuκsBepd6t5ocoalsosceaslsizNatFioκnBwpi6th cthoeloncualcilzeautsio(nDwAiPthI),twheerneudcleetuersm(DinAedPIb),ywmeereandseotefrImmiangeedJ bsoyftmweaarnes. *ofp I

Discussion
Olive Phenolic Compounds
Cell Cultures and Treatments
SA-β-Galactosidase Assay
Western Blot Analysis
NF-kB Immunofluorescence
Gelatin Zymography of Conditioned Media
Statistical Analysis
Findings
Conclusions
Full Text
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