Clinical Hemorheology and Microcirculation 58 (2014) 447–453 DOI 10.3233/CH-141807 IOS Press
447
Markers of cardiovascular risk in elderly patients with age-related macular degeneration J. Muleroa,∗ , N. Manresab , P. Zafrillaa and M. Losadab a b
Department of Food Technology and Nutrition, Catholic University of San Antonio, Murcia, Spain University Hospital Jose Ma Morales Meseguer, Murcia, Spain
Abstract. Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment and blindness among persons aged 60 years and older and many theories exist and feature mechanisms of oxidative stress, atherosclerotic-like changes, genetic predisposition, and inflammation in development of AMD. The aim of this study was to evaluate the association between markers of inflammation and cardiovascular risk with age-related macular degeneration. METHODS: Case-control study that includes 163 patients with wet AMD (age group of 55–82 years with the mean age of 71 years and 170 age-matched healthy controls in the age group of 55–78 years with the mean age of 71 years. The following parameters were determined: lipidic profile (Total Cholesterol, Triglycerides, HDL-c, LDL-c), CRP (C-Reactive Protein), homocysteine and fibrinogen. RESULTS: We found significant differences between AMD patients and control group in baseline values of homocysteine, CRP and fibrinogen, although we do not observed differences in levels of lipidic profile. CONCLUSION: Our data support the role of chronic inflammation in the development of AMD, however, further studies are needed to determine which common disease mechanisms of chronic inflammation and atherosclerosis contribute to the pathogenesis of AMD. Keywords: Cardiovascular risk, age-related macular degeneration, lipidic profile, C-Reactive protein, homocysteine
1. Introduction Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment and blindness among persons aged 60 years and older, and it’s etiology is not well understood. Many theories exist and feature mechanisms of oxidative stress, atherosclerotic-like changes, genetic predisposition, and inflammation in development of AMD [41]. Despite intensive basic and clinical research, its pathogenesis remains unclear, likely due to the multifactorial character [34, 37]. In addition to strong age-dependence of the disease, a complex interaction of metabolic, functional, genetic and environmental factors seems to create a stage for chronically developing changes in ocular structures of the macular region (choriocapillaries, Bruch’s membrane, retinal pigment epithelium RPE, photoreceptors) which may contribute to varying degrees to the onset and final picture of AMD [17, 36]. Many factors associated with AMD are also related to cardiovascular disease (CVD). Factors such as hypertension [26], previous vascular events [35], obesity [16], and diabetes [19], have been significantly associated with early and advanced AMD in several studies. ∗ Corresponding author: J. Mulero, Department of Food Technology and Nutrition, Catholic University of San Antonio, Murcia 30107, Spain. Tel.: +34 968278705; Fax: +34 968278622; E-mail: [email protected].
1386-0291/14/$27.50 © 2014 – IOS Press and the authors. All rights reserved
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J. Mulero et al. / Cardiovascular risk and age related macular degeneration
Many authors have hypothesized that cardiovascular disorders and AMD share common predisposing factors and proposed that novel biomarkers associated with CVD should be evaluated for their potential relationship with AMD [11, 16, 19, 23, 24, 35]. Recently, the role of inflammation has received considerable attention. One of the pathological hallmarks of AMD is the focal deposition of extracellular material between the retinal pigmented epithelium (RPE) and Bruch’s membrane. This material, known as drusen, is known to be composed of several cell components and humoral mediators of inflammatory and immunological processes (for example fibrinogen, and C reactive protein (CRP)) [23]. The investigation of inflammatory biomarkers in AMD is rendered even more biologically plausible by the observation that inflammation is associated with angiogenesis and that neovascularization can occur in inflammatory eye diseases [3]. Elevated homocysteine (hcy) levels have been shown to induce vascular injury, aiding in atherothrombogenesis and this has been considered as an independent risk factor for the development of vascular diseases [1, 41]. Several lines of evidence suggest that occlusion of choroidal vessels lead to the development of choroidal neovascularization which is a major determinant in promoting visual loss in patients with exudative AMD [2, 8]. The development and progression of AMD also has been associated with lipid levels [22]. Some authors [14, 24] report a significant association of cardiovascular disease and AMD. The number of patients with AMD and cardiovascular disease has significantly increased in recent years. It is known that there are certain markers that are common of both diseases, however, studies linking both pathologies are partial and focus on the study of only one or two markers. The objective of the current study is to further evaluate the association between markers of inflammation (CRP, fibrinogen) and cardiovascular risk (hcy and lipidic profile) with AMD.
2. Patients and methods 2.1. Patients and control subjects A cross-sectional study on a sample of 163 patients with wet AMD (age group of 55–82 years with the mean age of 71 ± 7.29 years (80 male and 83 female) and 170 age-matched healthy controls in the age group of 55–78 years with the mean age of 71 ± 6.68 years (88 male and 82 female) were recruited for the study. Patients were selected in the ophthalmology service at the University Hospital Morales Meseguer of Murcia and all patients included in the study had at least two years of monitoring disease in the hospital. The control group consists of people who live in or near Murcia areas and did not have them any kind of disease and they were selected randomly. AMD patients were diagnosed and underwent an eye examination consisted of the following tests: Corrected visual acuity−far/near; biomicroscopy of anterior segment; intraocular pressure measurement; retinography, angiography and OCT (Optical coherence Tomography). Subjects with history of diabetes mellitus, renal disease, hypertension, cardiovascular disease, smokers and alcoholics were excluded from the study. Patients with AMD and the control group had not taken any type of antioxidant supplements (vitamins B and acid folic influence on plasma levels of hcy). The physician and ophthalmologist ruled out any systemic/ophthalmic diseases from the control subjects before recruitment after a detailed check up. Informed consent was obtained from all the participants in the study. The authors’ institutional research and ethical committee approved the study (5 October 2010, register number: 3280). All procedures pertaining to human subjects strictly adhered to tenets of Helsinki declaration.
J. Mulero et al. / Cardiovascular risk and age related macular degeneration
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2.2. Biochemical determinations Blood samples were collected after ensuring overnight fasting and plasma was separated immediately. All the assays were performed on the same day. 2.3. Serum lipids The concentrations of cholesterol total, LDL, and HDL cholesterol (LDL-c and HDL-c, respectively), and triglycerides (TG) were assayed using automated systems (Cobas 711, Roche Diagnostics). 2.4. C-reactive protein (CRP) The analysis is performed by immunoturbidimetric test in which anti-CRP antibodies bound to latex microparticles react with the sample antigen forming an antigen-antibody. The agglutination is measured by turbidimetry and is directly proportional to the concentration of protein in the sample. 2.5. Homocysteine (hcy) Hcy levels were measured by quantitative determination by using a intensifying inmunonephelometric particle test in a BN ProSpec® analyzer (according to he protocol supplied in the kit for Siemens N Latex HCY OPAX 03). The reference interval for hcy concentration with the use of this method is from 4.9 to 14.0 ml/L. 2.6. Fibrinogen Fibrinogen estimations derived from the prothrombin time (PT-Fg) [32]. The PT is determined by optical density change for a range of plasma dilutions with known fibrinogen levels. The optical change for each different fibrinogen level is plotted as a calibration curve. A PT is performed on the patient’s platelet poor plasma and the fibrinogen is derived from the change in optical density compared to the calibration curve. 2.7. Statistical analysis All data were analyzed by using SPSS 17.0 statistical software (SPSS Inc., Chicago, IL). Descriptive statistic is presented as mean ± standard deviation. Means were compared by the variance test of repeated means. Analysis of variance (ANOVA) was used to examine significant differences in lipidic profile (Total Cholesterol, Triglycerides, HDL-c, LDL-c), CRP, hcy and fibrinogen of the two groups of study. A probability of less than 0.05 (p < 0.05) was considered statistically significant. 3. Results The levels of serum lipids determined inpatients and control subjects are given in Table 1. The differences in the results were not statistically significant in lipidic profile between the cases and controls, and in both groups the values of these parameters were within the normal range for healthy population.
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J. Mulero et al. / Cardiovascular risk and age related macular degeneration Table 1 Biochemical parameters of the study populations
Serum lipids (mg/dL) Total cholesterol Triglycerides HDL-c LDL-c Fibrinogen (g/L) CRP (mg/dL) Hcy (mol/L)
CG (n = 170)
AMD (n = 163)
201,1 ± 34.4 123.25 ± 41.3 63.41 ± 16.44 119.52 ± 38.8 2.76 ± 0.31 0.14 ± 0.07 10.35 ± 1.72
193.32 ± 36.6 113.12 ± 53.31 57.82 ± 14.64 112.88 ± 30.43 3.56 ± 0.67* 0.85 ± 0.09** 13.66 ± 1.47**
Reference values 131.4–201.0
447
Markers of cardiovascular risk in elderly patients with age-related macular degeneration J. Muleroa,∗ , N. Manresab , P. Zafrillaa and M. Losadab a b
Department of Food Technology and Nutrition, Catholic University of San Antonio, Murcia, Spain University Hospital Jose Ma Morales Meseguer, Murcia, Spain
Abstract. Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment and blindness among persons aged 60 years and older and many theories exist and feature mechanisms of oxidative stress, atherosclerotic-like changes, genetic predisposition, and inflammation in development of AMD. The aim of this study was to evaluate the association between markers of inflammation and cardiovascular risk with age-related macular degeneration. METHODS: Case-control study that includes 163 patients with wet AMD (age group of 55–82 years with the mean age of 71 years and 170 age-matched healthy controls in the age group of 55–78 years with the mean age of 71 years. The following parameters were determined: lipidic profile (Total Cholesterol, Triglycerides, HDL-c, LDL-c), CRP (C-Reactive Protein), homocysteine and fibrinogen. RESULTS: We found significant differences between AMD patients and control group in baseline values of homocysteine, CRP and fibrinogen, although we do not observed differences in levels of lipidic profile. CONCLUSION: Our data support the role of chronic inflammation in the development of AMD, however, further studies are needed to determine which common disease mechanisms of chronic inflammation and atherosclerosis contribute to the pathogenesis of AMD. Keywords: Cardiovascular risk, age-related macular degeneration, lipidic profile, C-Reactive protein, homocysteine
1. Introduction Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment and blindness among persons aged 60 years and older, and it’s etiology is not well understood. Many theories exist and feature mechanisms of oxidative stress, atherosclerotic-like changes, genetic predisposition, and inflammation in development of AMD [41]. Despite intensive basic and clinical research, its pathogenesis remains unclear, likely due to the multifactorial character [34, 37]. In addition to strong age-dependence of the disease, a complex interaction of metabolic, functional, genetic and environmental factors seems to create a stage for chronically developing changes in ocular structures of the macular region (choriocapillaries, Bruch’s membrane, retinal pigment epithelium RPE, photoreceptors) which may contribute to varying degrees to the onset and final picture of AMD [17, 36]. Many factors associated with AMD are also related to cardiovascular disease (CVD). Factors such as hypertension [26], previous vascular events [35], obesity [16], and diabetes [19], have been significantly associated with early and advanced AMD in several studies. ∗ Corresponding author: J. Mulero, Department of Food Technology and Nutrition, Catholic University of San Antonio, Murcia 30107, Spain. Tel.: +34 968278705; Fax: +34 968278622; E-mail: [email protected].
1386-0291/14/$27.50 © 2014 – IOS Press and the authors. All rights reserved
448
J. Mulero et al. / Cardiovascular risk and age related macular degeneration
Many authors have hypothesized that cardiovascular disorders and AMD share common predisposing factors and proposed that novel biomarkers associated with CVD should be evaluated for their potential relationship with AMD [11, 16, 19, 23, 24, 35]. Recently, the role of inflammation has received considerable attention. One of the pathological hallmarks of AMD is the focal deposition of extracellular material between the retinal pigmented epithelium (RPE) and Bruch’s membrane. This material, known as drusen, is known to be composed of several cell components and humoral mediators of inflammatory and immunological processes (for example fibrinogen, and C reactive protein (CRP)) [23]. The investigation of inflammatory biomarkers in AMD is rendered even more biologically plausible by the observation that inflammation is associated with angiogenesis and that neovascularization can occur in inflammatory eye diseases [3]. Elevated homocysteine (hcy) levels have been shown to induce vascular injury, aiding in atherothrombogenesis and this has been considered as an independent risk factor for the development of vascular diseases [1, 41]. Several lines of evidence suggest that occlusion of choroidal vessels lead to the development of choroidal neovascularization which is a major determinant in promoting visual loss in patients with exudative AMD [2, 8]. The development and progression of AMD also has been associated with lipid levels [22]. Some authors [14, 24] report a significant association of cardiovascular disease and AMD. The number of patients with AMD and cardiovascular disease has significantly increased in recent years. It is known that there are certain markers that are common of both diseases, however, studies linking both pathologies are partial and focus on the study of only one or two markers. The objective of the current study is to further evaluate the association between markers of inflammation (CRP, fibrinogen) and cardiovascular risk (hcy and lipidic profile) with AMD.
2. Patients and methods 2.1. Patients and control subjects A cross-sectional study on a sample of 163 patients with wet AMD (age group of 55–82 years with the mean age of 71 ± 7.29 years (80 male and 83 female) and 170 age-matched healthy controls in the age group of 55–78 years with the mean age of 71 ± 6.68 years (88 male and 82 female) were recruited for the study. Patients were selected in the ophthalmology service at the University Hospital Morales Meseguer of Murcia and all patients included in the study had at least two years of monitoring disease in the hospital. The control group consists of people who live in or near Murcia areas and did not have them any kind of disease and they were selected randomly. AMD patients were diagnosed and underwent an eye examination consisted of the following tests: Corrected visual acuity−far/near; biomicroscopy of anterior segment; intraocular pressure measurement; retinography, angiography and OCT (Optical coherence Tomography). Subjects with history of diabetes mellitus, renal disease, hypertension, cardiovascular disease, smokers and alcoholics were excluded from the study. Patients with AMD and the control group had not taken any type of antioxidant supplements (vitamins B and acid folic influence on plasma levels of hcy). The physician and ophthalmologist ruled out any systemic/ophthalmic diseases from the control subjects before recruitment after a detailed check up. Informed consent was obtained from all the participants in the study. The authors’ institutional research and ethical committee approved the study (5 October 2010, register number: 3280). All procedures pertaining to human subjects strictly adhered to tenets of Helsinki declaration.
J. Mulero et al. / Cardiovascular risk and age related macular degeneration
449
2.2. Biochemical determinations Blood samples were collected after ensuring overnight fasting and plasma was separated immediately. All the assays were performed on the same day. 2.3. Serum lipids The concentrations of cholesterol total, LDL, and HDL cholesterol (LDL-c and HDL-c, respectively), and triglycerides (TG) were assayed using automated systems (Cobas 711, Roche Diagnostics). 2.4. C-reactive protein (CRP) The analysis is performed by immunoturbidimetric test in which anti-CRP antibodies bound to latex microparticles react with the sample antigen forming an antigen-antibody. The agglutination is measured by turbidimetry and is directly proportional to the concentration of protein in the sample. 2.5. Homocysteine (hcy) Hcy levels were measured by quantitative determination by using a intensifying inmunonephelometric particle test in a BN ProSpec® analyzer (according to he protocol supplied in the kit for Siemens N Latex HCY OPAX 03). The reference interval for hcy concentration with the use of this method is from 4.9 to 14.0 ml/L. 2.6. Fibrinogen Fibrinogen estimations derived from the prothrombin time (PT-Fg) [32]. The PT is determined by optical density change for a range of plasma dilutions with known fibrinogen levels. The optical change for each different fibrinogen level is plotted as a calibration curve. A PT is performed on the patient’s platelet poor plasma and the fibrinogen is derived from the change in optical density compared to the calibration curve. 2.7. Statistical analysis All data were analyzed by using SPSS 17.0 statistical software (SPSS Inc., Chicago, IL). Descriptive statistic is presented as mean ± standard deviation. Means were compared by the variance test of repeated means. Analysis of variance (ANOVA) was used to examine significant differences in lipidic profile (Total Cholesterol, Triglycerides, HDL-c, LDL-c), CRP, hcy and fibrinogen of the two groups of study. A probability of less than 0.05 (p < 0.05) was considered statistically significant. 3. Results The levels of serum lipids determined inpatients and control subjects are given in Table 1. The differences in the results were not statistically significant in lipidic profile between the cases and controls, and in both groups the values of these parameters were within the normal range for healthy population.
450
J. Mulero et al. / Cardiovascular risk and age related macular degeneration Table 1 Biochemical parameters of the study populations
Serum lipids (mg/dL) Total cholesterol Triglycerides HDL-c LDL-c Fibrinogen (g/L) CRP (mg/dL) Hcy (mol/L)
CG (n = 170)
AMD (n = 163)
201,1 ± 34.4 123.25 ± 41.3 63.41 ± 16.44 119.52 ± 38.8 2.76 ± 0.31 0.14 ± 0.07 10.35 ± 1.72
193.32 ± 36.6 113.12 ± 53.31 57.82 ± 14.64 112.88 ± 30.43 3.56 ± 0.67* 0.85 ± 0.09** 13.66 ± 1.47**
Reference values 131.4–201.0
