Age effect on HSP70: decreased resistance to ischemic and oxidative stress in HDF.
BACKGROUND
Heat pre-conditioning results in induction of heat shock proteins including HSP70 that gives a cytoprotective effect against further stress. However, HSP70 induction is attenuated in aged cells. The lower HSP70-levels may contribute to the impaired stress response seen in the aged, and to the higher rates of chronic wounds in aged, which arise from repeated ischemia-reperfusion injury. The aim of this study was to investigate a possible connection by comparing the viability of heat pre-conditioned aged versus young human dermal fibroblasts (HDF) after exposure to stress.


METHODS
Young (15-28) and aged (61-77) HDF were heat pre-conditioned (42 degrees C, 1 h) and after recovery (1, 2, or 20 h) treated with carbonyl-cyanide-m-chlorophenylhydrazone (hypoxic stress) or with hydrogen peroxide (oxidative stress) for 1 h. HSP70 levels were determined by Western blot. Cell damage was assessed by quantifying lactic dehydrogenase (LDH) in conditioned media. Aged HDF were transfected with HSP70-plasmid, consecutively heat pre-conditioned and exposed to oxidative stress.


RESULTS
HSP70 increased in heat pre-conditioned young HDF by 96, 189, and 237% after 1, 2, and 20-h recovery, respectively, and in aged HDF by 27, 61, and 26%. LDH-release was only decreased in young HDF 20-h after heat-treatment compared with non-heat treated cells (P < 0.001). HSP70-transfection of aged HDF with plasmid reduced LDH-release by 29%.


CONCLUSIONS
Heat pre-conditioning fails to protect aged HDF to oxidative or hypoxic stress due in part to impaired HSP70 induction compared to young.
Tandara
Andrea A
AA
Wound Healing Research Laboratory, Division of Plastic & Reconstructive Surgery, Northwestern University, Chicago, Illinois 60611, USA.
Kloeters
Oliver
O
Kim
Injoong
I
Mogford
Jon E
JE
Mustoe
Thomas A
TA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000187:drug effects / Q000502:physiology*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D015687:Cell Hypoxia / Q000187:drug effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007511:Ischemia / Q000517:prevention & control; D007770:L-Lactate Dehydrogenase; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010957:Plasmids; D012867:Skin / Q000098:blood supply / Q000187:drug effects; D015595:Skin Aging; D012879:Skin Physiological Phenomena; D014162:Transfection; D014475:Uncoupling Agents / Q000494:pharmacology
D018840:HSP70 Heat-Shock Proteins; D014475:Uncoupling Agents; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D007770:L-Lactate Dehydrogenase