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Cholinesterase inhibitors exert a protective effect on endothelial damage in Alzheimer disease patients
Journal of the Neurological Sciences 229–230 (2005) 211 – 213 www.elsevier.com/locate/jns
Cholinesterase inhibitors exert a protective effect on endothelial damage in Alzheimer disease patients Barbara Borronia, Chiara Agostia, Giuliana Martinib, Roberta Volpib, Cristina Brambillaa, Luigi Caimib, Monica Di Lucac, Alessandro Padovania,* a
Department of Medical Sciences, Neurological Clinic, University of Brescia, Italy b Department of Biochemistry, University of Brescia, Italy c Institute of Pharmacological Sciences, Center of Excellence for Neurodegenerative Disorders, University of Milan, Italy Available online 8 December 2004
Abstract It has been recently suggested that in Alzheimer disease (AD), the current available therapy with cholinesterase inhibitors (ChEIs) influences platelets amyloid precursor protein (APP) metabolism towards the nonamyloidogenic pathway. In order to investigate whether ChEIs may exert a protective role on vascular damage due to abeta deposition, several parameters of coagulation and fibrinolysis were assessed. Twenty patients with mild AD and 30 age-matched controls entered the study. All subjects performed a multidimensional neuropsychological assessment and a laboratory protocol. Individuals with vascular risk factors and systemic diseases were excluded. In mild AD patients, increased levels of markers of endothelial dysfunction, such as thrombomodulin (TM) and sE-selectin (sE-sel), were seen. After 1-month ChEIs treatment, a significant reduction of TM ( pb0.05) and sE-sel ( pb0.05) values towards the normal range was observed. These findings suggest that endothelial-related ChEIs action might contribute to the clinical efficacy in AD, slowing down pathology progression. D 2004 Elsevier B.V. All rights reserved. Keywords: Alzheimer disease; Cholinesterase inhibitors; Amyloid precursor protein
1. Introduction It is well established that short- and long-symptomatic treatment with cholinesterase inhibitors (ChEIs) improves cognition in Alzheimer disease (AD) patients [1]. Recent data demonstrated also a cholinergic effect of these drugs on amyloid precursor protein (APP) metabolism, influencing one of the most relevant molecular mechanisms for disease pathogenesis. It has been shown that in superfused rat cortical brain slices and cultured neuroblastoma cells, ChEIs increase the release of sAPPa,? the nonamyloidogenic product of APP processing, in proportion to the degree of * Corresponding author. II Clinica Neurologica, Spedali Civili di Brescia, Universita` degli Studi di Brescia, Italy. Tel.: +39 30 3995631; fax: +39 30 3995027. E-mail address: [email protected] (A. Padovani). 0022-510X/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jns.2004.11.030
ChEIs inhibition [2,3]. Furthermore, a recent study suggests that ChEIs, at a dosage commonly administered in clinical practice, modify APP processing in a peripheral cell. In fact, in AD patients, the decrease of platelet APP forms ratio [4] is reduced to normal values by 1-month ChEIs therapy [5,6]. Platelets had been suggested to play a major role in the origin of deposited Ah in cerebral vasculature, as they contain a large amount of circulating APP [7]. Moreover, it has been recently demonstrated that AD patients, who have never been exposed to ChEIs, present increased levels of endothelial markers related to vascular damage since the mild stages of the disease. It may be argued that changes of the pattern of platelet APP forms, which parallel the impairment of sAPPa release, might contribute to endothelial damage both through an increased Ah production and its vascular deposition [8].
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B. Borroni et al. / Journal of the Neurological Sciences 229–230 (2005) 211–213
These data, taken together with ChEIs effect in restoring APP forms ratio in platelets, may indicate a possible protective role of these drugs on vascular damage in AD [5,6]. In order to investigate this hypothesis, we evaluated some selected parameters mapping endothelial and haemostasis dysfunction in mild AD patients, before and after 1 month ChEIs therapy (Donepezil, 5 mg daily), and in agematched controls (CON).
2. Methods The study was carried out in a group of subjects with probable AD consecutively evaluated at the Clinica Neurologica, University of Brescia, Italy. The study was conducted in accordance with local clinical research regulations, and informed consent was obtained from all subjects and caregivers. All participants received a medical, epidemiological, and neuropsychological assessment. All the subjects were also subjected to laboratory examinations, including red blood cell count, white blood cell total, and differential count with formula, erythrocyte sedimentation velocity, vitamin B12 and folate levels, and thyroid function measurements. Additional diagnostic testing for AD patients including neuroimaging (CT or MRI), blood tests, and other evaluations as needed were performed. A diagnosis of dementia was made according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria. A diagnosis of probable Alzheimer disease was based on National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer’s Disease and Related Disorders Association (NINCDSADRDA) criteria. Dementia severity, measured by The Clinical Dementia Rating (CDR) scale, was utilised to measure dementia severity, and only patients with CDR score b1 were included in this study. Demographic and clinical characteristics are shown in Table 1. At baseline and at follow-up visits, each subject underwent a clinical and neuropsychological evaluation including the Mini-Mental State Examination (MMSE) and venipuncture for measurement of (a) endothelial leukocyte adhesion Table1 Demographic and clinical characteristics of the examined population Variables
CON (n=30)
AD (n=20)
p
Age (years) Gender (F/M) Education (years) Disease duration (years) CDR MMSE score
71.0F8.8 17/13 6.5F3.1 – 0 28.6F1.2
70.4F7.6 12/8 6.0F3.8 3.2F1.1 0.8F0.9 24.4F4.2
n.s. n.s. n.s. – 0.0001 0.0001
Results are expressed as meanFstandard deviation; CON: control subjects; AD: Alzheimer disease; CDR: Clinical Dementia Rating; MMSE: MiniMental State Examination; F: female; M: male.
molecule-1 (sE-selectin), a protein belonging to the selectin family of adhesion molecules (together with L-selectin and P-selectin) mediating the initial interactions of leukocytes and platelets with endothelial cells; (b) thrombomodulin (TM) and h?-thromboglobulin (h-TG), which are markers of endothelial and platelet activation, respectively; (c) von Willebrand factor (vWF), a prothrombotic molecule released from endothelial cells when they are injured or stimulated by factors, such as thrombin; (d) fibrinogen, as a marker of developing atherothrombotic disease; and (e) prothrombin fragment (F 1+2), marker of the actual amount of formed thrombin. Particular care was devoted to inclusion/exclusion criteria in order to exclude individuals with major vascular risk factors or active inflammatory diseases and avoid individuals on confounding drugs, such as corticosteroids, nonsteroidalantin inflammatory agents, antiplatelets drugs, or anticoagulant.
3. Results Compared to cortiles (CON), mild AD patients present significantly increased levels of TM (CON=6.05F1.9 vs. AD=13.3F8.2 ng/ml, p b0.0001) and sE-selectin (CON=30.3F18.2 vs. AD=41.8F36.4 ng/ml, pb0.03). In contrast, no difference was found between the two diagnostic groups in the levels of h-TG (CON vs. AD, 68.4F424.4 vs. 79.7F40.1 UI/ml), prothrombin fragment 1+2 (CON=1.2F0.9 vs. AD=1.2F0.5 nmol/l), fibrinogen (CON=346.7F102.1 vs. AD=378.3F99.7 mg/dl), and von W i l l e b r a n d f a c t o r ( C O N = 1 2 7 . 8 F6 4 . 7 % v s . AD=130.5F29.8%). After 1 month of ChEIs therapy, AD patients showed a significant reduction in both TM (8.2F5.9, pb0.05) and Eselectin (28.9F22.1, pb0.05) levels. These data extend previous clinical and experimental reports claiming for endothelial abnormalities in AD since the mild stages and argue for a vascular protective effect of ChEIs treatment [9,10].
4. Discussion The explanation for such early endothelial dysfunction in AD is not immediate as only subjects with no overt atherosclerosis or vascular pathology entered this study. Several experimental lines of evidence have shown that Ah?, which is central in the pathology of AD, causes a loss of endothelial function. In particular, it has been recently claimed that Ah determines a perturbation in cell–cell and cell–matrix interaction, thus predisposing to increased adhesiveness of endothelium and leukocytes [11,12]. Moreover, it has been demonstrated that a modest increase in concentration of Ah above its normal physiological level in circulation, as found in early AD stages, results in decreased
B. Borroni et al. / Journal of the Neurological Sciences 229–230 (2005) 211–213
NO production, an increase of reactive oxygen species, and a lower sensitivity to endothelium-dependent vasodilatation [13]. In view of our observations, ChEIs may exert an adjunctive protective role on endothelial dysfunction related to AD, beyond the well-known effect on increasing the availability of acetylcholine in neuronal compartment [1]. Understanding of the molecular mechanism responsible for rescuing endothelial damage in patients with AD after donepezil treatment still needs further investigation. We suggest that ChEIs administration in the early stages could reduce Ah toxicity on vasculature decreasing its production via APP processing influence. Further studies are needed to evaluate the mechanisms by which ChEIs may play a cytoprotective role and the effect of long-term treatment on endothelial function. These observations could have several implications in clinical practice, because it is well established that AD is not only associated with neuronal but also vascular damage, and future therapeutic strategies should be drawn taking into consideration both these aspects. Our findings suggest that endothelialrelated ChEIs action might contribute to the clinical efficacy in AD, slowing down pathology progression. References [1] Giacobini E. Cholinestarese inhibitors: from the Calebar bean to Alzheimer therapy. In: Giacobini E, editor. Cholinesterase and cholinesterase inhibitors. London7 Martin Dunitz, 2000; p. 181 – 226. [2] Racchi M, Govoni S. Rationalizing a pharmacological intervention on the amyloid precursor protein metabolism. Trends Pharmacol Sci 1999;20:418 – 23.
213
[3] Rossner S, Ueberham U, Yu J, Kirazov L, Schliebs R, Perez-Polo JR, et al. In vivo regulation of amyloid precursor protein secretion in rat neocortex by cholinergic activity. Eur J Neurosci 1997;9(10): 2125 – 34. [4] Padovani A, Pastorino L, Borroni B, et al. Amyloid precursor protein in platelets: a peripheral marker for the diagnosis of sporadic AD. Neurology 2001;57:2243 – 8. [5] Borroni B, Colciaghi F, Pastorino L, et al. Amyloid precursor protein in platelets of patients with Alzheimer disease: effect of acetylcholinesterase inhibitor treatment. Arch Neurol 2001;58:442 – 6. [6] Borroni B, Colciaghi F, Pastorino L, et al. ApoE genotype influences the biological effect of donepezil on APP metabolism in Alzheimer disease: evidence from a peripheral model. Eur Neuropsychopharmacol 2002;12:195 – 200. [7] Gardella JE, Ghiso J, Gorgone GA, Marratta D, Kaplan AP, Frangione B, et al. Intact Alzheimer amyloid precursor protein (APP) is present in platelet membranes and is encoded by platelet mRNA. Biochem Biophys Res Commun 1990;173(3):1292 – 8. [8] Colciaghi F, Marcello E, Borroni B, Zimmermann M, Caltagirone C, Cattabeni F, et al. Platelet APP, ADAM 10 and BACE alterations in the early stages of Alzheimer disease. Neurology 2004;62(3): 498 – 501. [9] Mari D, Parnetti L, Coppola R, Bottasso B, Reboldi GP, Senin U, et al. Hemostasis abnormalities in patients with vascular dementia and Alzheimer’s disease. Thromb Haemost 1996;75(2):216 – 8. [10] Borroni B, Volpi R, Martini G, Del Bono R, Archetti S, Colciaghi F, et al. Peripheral blood abnormalities in Alzheimer disease: evidence for early endothelial dysfunction. Alzheimer Dis Assoc Disord 2002; 16(3):150 – 5. [11] Kalaria RN, Hedera P. h-Amyloid vasoactivity in Alzheimer’s disease. Lancet 1996;347:1492 – 3. [12] Thomas T, Thomas G, McLendon C, Sutton T, Mullan M. Beta amyloid mediated vasoactivity and vascular endothelial damage. Nature 1996;380(6570):168 – 71. [13] Crawford F, Suo Z, Fang C, et al. Charaterization of the in vitro vasoactivity of Abeta peptide. Exp Neurol 1998;150:159 – 68.
Cholinesterase inhibitors exert a protective effect on endothelial damage in Alzheimer disease patients Barbara Borronia, Chiara Agostia, Giuliana Martinib, Roberta Volpib, Cristina Brambillaa, Luigi Caimib, Monica Di Lucac, Alessandro Padovania,* a
Department of Medical Sciences, Neurological Clinic, University of Brescia, Italy b Department of Biochemistry, University of Brescia, Italy c Institute of Pharmacological Sciences, Center of Excellence for Neurodegenerative Disorders, University of Milan, Italy Available online 8 December 2004
Abstract It has been recently suggested that in Alzheimer disease (AD), the current available therapy with cholinesterase inhibitors (ChEIs) influences platelets amyloid precursor protein (APP) metabolism towards the nonamyloidogenic pathway. In order to investigate whether ChEIs may exert a protective role on vascular damage due to abeta deposition, several parameters of coagulation and fibrinolysis were assessed. Twenty patients with mild AD and 30 age-matched controls entered the study. All subjects performed a multidimensional neuropsychological assessment and a laboratory protocol. Individuals with vascular risk factors and systemic diseases were excluded. In mild AD patients, increased levels of markers of endothelial dysfunction, such as thrombomodulin (TM) and sE-selectin (sE-sel), were seen. After 1-month ChEIs treatment, a significant reduction of TM ( pb0.05) and sE-sel ( pb0.05) values towards the normal range was observed. These findings suggest that endothelial-related ChEIs action might contribute to the clinical efficacy in AD, slowing down pathology progression. D 2004 Elsevier B.V. All rights reserved. Keywords: Alzheimer disease; Cholinesterase inhibitors; Amyloid precursor protein
1. Introduction It is well established that short- and long-symptomatic treatment with cholinesterase inhibitors (ChEIs) improves cognition in Alzheimer disease (AD) patients [1]. Recent data demonstrated also a cholinergic effect of these drugs on amyloid precursor protein (APP) metabolism, influencing one of the most relevant molecular mechanisms for disease pathogenesis. It has been shown that in superfused rat cortical brain slices and cultured neuroblastoma cells, ChEIs increase the release of sAPPa,? the nonamyloidogenic product of APP processing, in proportion to the degree of * Corresponding author. II Clinica Neurologica, Spedali Civili di Brescia, Universita` degli Studi di Brescia, Italy. Tel.: +39 30 3995631; fax: +39 30 3995027. E-mail address: [email protected] (A. Padovani). 0022-510X/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jns.2004.11.030
ChEIs inhibition [2,3]. Furthermore, a recent study suggests that ChEIs, at a dosage commonly administered in clinical practice, modify APP processing in a peripheral cell. In fact, in AD patients, the decrease of platelet APP forms ratio [4] is reduced to normal values by 1-month ChEIs therapy [5,6]. Platelets had been suggested to play a major role in the origin of deposited Ah in cerebral vasculature, as they contain a large amount of circulating APP [7]. Moreover, it has been recently demonstrated that AD patients, who have never been exposed to ChEIs, present increased levels of endothelial markers related to vascular damage since the mild stages of the disease. It may be argued that changes of the pattern of platelet APP forms, which parallel the impairment of sAPPa release, might contribute to endothelial damage both through an increased Ah production and its vascular deposition [8].
212
B. Borroni et al. / Journal of the Neurological Sciences 229–230 (2005) 211–213
These data, taken together with ChEIs effect in restoring APP forms ratio in platelets, may indicate a possible protective role of these drugs on vascular damage in AD [5,6]. In order to investigate this hypothesis, we evaluated some selected parameters mapping endothelial and haemostasis dysfunction in mild AD patients, before and after 1 month ChEIs therapy (Donepezil, 5 mg daily), and in agematched controls (CON).
2. Methods The study was carried out in a group of subjects with probable AD consecutively evaluated at the Clinica Neurologica, University of Brescia, Italy. The study was conducted in accordance with local clinical research regulations, and informed consent was obtained from all subjects and caregivers. All participants received a medical, epidemiological, and neuropsychological assessment. All the subjects were also subjected to laboratory examinations, including red blood cell count, white blood cell total, and differential count with formula, erythrocyte sedimentation velocity, vitamin B12 and folate levels, and thyroid function measurements. Additional diagnostic testing for AD patients including neuroimaging (CT or MRI), blood tests, and other evaluations as needed were performed. A diagnosis of dementia was made according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria. A diagnosis of probable Alzheimer disease was based on National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer’s Disease and Related Disorders Association (NINCDSADRDA) criteria. Dementia severity, measured by The Clinical Dementia Rating (CDR) scale, was utilised to measure dementia severity, and only patients with CDR score b1 were included in this study. Demographic and clinical characteristics are shown in Table 1. At baseline and at follow-up visits, each subject underwent a clinical and neuropsychological evaluation including the Mini-Mental State Examination (MMSE) and venipuncture for measurement of (a) endothelial leukocyte adhesion Table1 Demographic and clinical characteristics of the examined population Variables
CON (n=30)
AD (n=20)
p
Age (years) Gender (F/M) Education (years) Disease duration (years) CDR MMSE score
71.0F8.8 17/13 6.5F3.1 – 0 28.6F1.2
70.4F7.6 12/8 6.0F3.8 3.2F1.1 0.8F0.9 24.4F4.2
n.s. n.s. n.s. – 0.0001 0.0001
Results are expressed as meanFstandard deviation; CON: control subjects; AD: Alzheimer disease; CDR: Clinical Dementia Rating; MMSE: MiniMental State Examination; F: female; M: male.
molecule-1 (sE-selectin), a protein belonging to the selectin family of adhesion molecules (together with L-selectin and P-selectin) mediating the initial interactions of leukocytes and platelets with endothelial cells; (b) thrombomodulin (TM) and h?-thromboglobulin (h-TG), which are markers of endothelial and platelet activation, respectively; (c) von Willebrand factor (vWF), a prothrombotic molecule released from endothelial cells when they are injured or stimulated by factors, such as thrombin; (d) fibrinogen, as a marker of developing atherothrombotic disease; and (e) prothrombin fragment (F 1+2), marker of the actual amount of formed thrombin. Particular care was devoted to inclusion/exclusion criteria in order to exclude individuals with major vascular risk factors or active inflammatory diseases and avoid individuals on confounding drugs, such as corticosteroids, nonsteroidalantin inflammatory agents, antiplatelets drugs, or anticoagulant.
3. Results Compared to cortiles (CON), mild AD patients present significantly increased levels of TM (CON=6.05F1.9 vs. AD=13.3F8.2 ng/ml, p b0.0001) and sE-selectin (CON=30.3F18.2 vs. AD=41.8F36.4 ng/ml, pb0.03). In contrast, no difference was found between the two diagnostic groups in the levels of h-TG (CON vs. AD, 68.4F424.4 vs. 79.7F40.1 UI/ml), prothrombin fragment 1+2 (CON=1.2F0.9 vs. AD=1.2F0.5 nmol/l), fibrinogen (CON=346.7F102.1 vs. AD=378.3F99.7 mg/dl), and von W i l l e b r a n d f a c t o r ( C O N = 1 2 7 . 8 F6 4 . 7 % v s . AD=130.5F29.8%). After 1 month of ChEIs therapy, AD patients showed a significant reduction in both TM (8.2F5.9, pb0.05) and Eselectin (28.9F22.1, pb0.05) levels. These data extend previous clinical and experimental reports claiming for endothelial abnormalities in AD since the mild stages and argue for a vascular protective effect of ChEIs treatment [9,10].
4. Discussion The explanation for such early endothelial dysfunction in AD is not immediate as only subjects with no overt atherosclerosis or vascular pathology entered this study. Several experimental lines of evidence have shown that Ah?, which is central in the pathology of AD, causes a loss of endothelial function. In particular, it has been recently claimed that Ah determines a perturbation in cell–cell and cell–matrix interaction, thus predisposing to increased adhesiveness of endothelium and leukocytes [11,12]. Moreover, it has been demonstrated that a modest increase in concentration of Ah above its normal physiological level in circulation, as found in early AD stages, results in decreased
B. Borroni et al. / Journal of the Neurological Sciences 229–230 (2005) 211–213
NO production, an increase of reactive oxygen species, and a lower sensitivity to endothelium-dependent vasodilatation [13]. In view of our observations, ChEIs may exert an adjunctive protective role on endothelial dysfunction related to AD, beyond the well-known effect on increasing the availability of acetylcholine in neuronal compartment [1]. Understanding of the molecular mechanism responsible for rescuing endothelial damage in patients with AD after donepezil treatment still needs further investigation. We suggest that ChEIs administration in the early stages could reduce Ah toxicity on vasculature decreasing its production via APP processing influence. Further studies are needed to evaluate the mechanisms by which ChEIs may play a cytoprotective role and the effect of long-term treatment on endothelial function. These observations could have several implications in clinical practice, because it is well established that AD is not only associated with neuronal but also vascular damage, and future therapeutic strategies should be drawn taking into consideration both these aspects. Our findings suggest that endothelialrelated ChEIs action might contribute to the clinical efficacy in AD, slowing down pathology progression. References [1] Giacobini E. Cholinestarese inhibitors: from the Calebar bean to Alzheimer therapy. In: Giacobini E, editor. Cholinesterase and cholinesterase inhibitors. London7 Martin Dunitz, 2000; p. 181 – 226. [2] Racchi M, Govoni S. Rationalizing a pharmacological intervention on the amyloid precursor protein metabolism. Trends Pharmacol Sci 1999;20:418 – 23.
213
[3] Rossner S, Ueberham U, Yu J, Kirazov L, Schliebs R, Perez-Polo JR, et al. In vivo regulation of amyloid precursor protein secretion in rat neocortex by cholinergic activity. Eur J Neurosci 1997;9(10): 2125 – 34. [4] Padovani A, Pastorino L, Borroni B, et al. Amyloid precursor protein in platelets: a peripheral marker for the diagnosis of sporadic AD. Neurology 2001;57:2243 – 8. [5] Borroni B, Colciaghi F, Pastorino L, et al. Amyloid precursor protein in platelets of patients with Alzheimer disease: effect of acetylcholinesterase inhibitor treatment. Arch Neurol 2001;58:442 – 6. [6] Borroni B, Colciaghi F, Pastorino L, et al. ApoE genotype influences the biological effect of donepezil on APP metabolism in Alzheimer disease: evidence from a peripheral model. Eur Neuropsychopharmacol 2002;12:195 – 200. [7] Gardella JE, Ghiso J, Gorgone GA, Marratta D, Kaplan AP, Frangione B, et al. Intact Alzheimer amyloid precursor protein (APP) is present in platelet membranes and is encoded by platelet mRNA. Biochem Biophys Res Commun 1990;173(3):1292 – 8. [8] Colciaghi F, Marcello E, Borroni B, Zimmermann M, Caltagirone C, Cattabeni F, et al. Platelet APP, ADAM 10 and BACE alterations in the early stages of Alzheimer disease. Neurology 2004;62(3): 498 – 501. [9] Mari D, Parnetti L, Coppola R, Bottasso B, Reboldi GP, Senin U, et al. Hemostasis abnormalities in patients with vascular dementia and Alzheimer’s disease. Thromb Haemost 1996;75(2):216 – 8. [10] Borroni B, Volpi R, Martini G, Del Bono R, Archetti S, Colciaghi F, et al. Peripheral blood abnormalities in Alzheimer disease: evidence for early endothelial dysfunction. Alzheimer Dis Assoc Disord 2002; 16(3):150 – 5. [11] Kalaria RN, Hedera P. h-Amyloid vasoactivity in Alzheimer’s disease. Lancet 1996;347:1492 – 3. [12] Thomas T, Thomas G, McLendon C, Sutton T, Mullan M. Beta amyloid mediated vasoactivity and vascular endothelial damage. Nature 1996;380(6570):168 – 71. [13] Crawford F, Suo Z, Fang C, et al. Charaterization of the in vitro vasoactivity of Abeta peptide. Exp Neurol 1998;150:159 – 68.