title: Increased susceptibility to oxidative death of lymphocytes from Alzheimer patients correlates with dementia severity.
abstract: We previously reported on enhanced susceptibility to death of lymphocytes from Alzheimer's disease (AD) patients when exposed to hydrogen peroxide (H2O2)-induced oxidative stress and an increased resistance to death in those of patients with a history of skin cancer. This is consistent with our hypothesis proposing that the cellular machinery controlling cell death is deregulated in opposite directions in Alzheimer's disease (AD) and cancer, to explain the inverse association observed in epidemiological studies. Here we investigated whether the observed increased susceptibility correlates with the degree of dementia severity. Peripheral lymphocytes from 23 AD patients, classified using the Clinical Dementia Rating (CDR) into severe dementia (CDR 3, n=10) and mild-to-moderate dementia (CDR 1- 2, n=13), and 15 healthy controls (HC) (CDR 0), were exposed to H2O2 for 20 hours. Lymphocyte death was determined by flow cytometry and propidium iodide staining. The greatest susceptibility to H2O2-induced death was observed for lymphocytes from severe dementia patients, whereas those with mild-to-moderate dementia exhibited intermediate values, compared to healthy controls. A significant increase in the apoptosis/necrosis ratio was found in AD patients. Poly (ADP-ribosyl) polymerase-1 (PARP-1) inhibition significantly protected from H2O2-induced death of lymphocytes, whereby a lower degree of protection was observed in severe AD patients. Moreover, inhibition of PARP-1 abolished the differences in apoptosis/necrosis ratios observed between the three groups of patients. These results support the notion that AD is a systemic disorder, whereby enhanced susceptibility to H2O2-induced death in peripheral lymphocytes correlates with dementia severity and enhanced death in AD patients is attributable to a PARP-dependent increase in the apoptosis/necrosis ratio.
authors.forename: Daniela P
authors.initials: DP
authors.lastname: Ponce
authors.forename: Felipe
authors.initials: F
authors.lastname: Salech
authors.forename: Carol D
authors.initials: CD
authors.lastname: SanMartin
authors.forename: Monica
authors.initials: M
authors.lastname: Silva
authors.forename: Chengjie
authors.initials: C
authors.lastname: Xiong
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Roe
authors.forename: Mauricio
authors.initials: M
authors.lastname: Henriquez
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Quest
authors.affiliation: Departamento de Neurologia y Neurocirugia, Hospital Clinico Universidad de Chile, Santos Dumont 999, Independencia, Santiago de Chile. CP: 8380430. behrensl@u.uchile.cl.
authors.forename: Maria I
authors.initials: MI
authors.lastname: Behrens
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D004198:Disease Susceptibility; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D008214:Lymphocytes / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009336:Necrosis / Q000188:drug therapy / Q000503:physiopathology*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011569:Psychiatric Status Rating Scales
chemical_list: D000975:Antioxidants; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D006861:Hydrogen Peroxide; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases