Oxidative stress and reduced antioxidative status, along with endothelial dysfunction in acromegaly

High chitotriosidase and AGE levels in acromegaly: a case-control study

PURPOSE

Acromegaly is associated with oxidative stress and inflammation parameters. Chitotriosidase (CHITO) is a marker of macrophage activation and plays a pivotal role in the activation of inflammatory and immunological responses. Our study aimed to determine CHITO,YKL-40, advanced glycation end product (AGE), and high-sensitivity C-reactive protein (hsCRP) levels to investigate malondialdehyde (MDA), catalase, superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities and to evaluate any association of these parameters with carotid intima media thickness (cIMT) in patients with controlled acromegaly.

METHODS

Thirty controlled acromegaly patients and 41 age- and sex-matched control cases were studied. We obtained demographic data, hormonal and metabolic parameters, and cIMT. CHITO activity was measured with the fluorometric method of Chamoles et al. YKL-40 and hsCRP levels were measured using ELISA. AGEs were measured based on spectrofluorimetric detection. GSH-Px activity was determined by a colorimetric assay. MDA, SOD, and catalase activities were determined in hemolysis.

RESULTS

Higher CHITO, AGE, and hsCRP concentrations were observed in patients with acromegaly compared to controls. SOD levels were non-significantly higher in the acromegaly group, while catalase activities were lower in patients with acromegaly. Correlation analyses of CHITO, AGEs, YKL-40, hsCRP, MDA, catalase, GSH-Px, and SOD with metabolic, anthropometric, and laboratory parameters did not demonstrate any significant correlation (p > 0.05). There was no significant difference between groups with regard to cIMT levels.

CONCLUSION

This is the first study investigating CHITO and AGE levels in patients with acromegaly. Serum CHITO, AGE, and hsCRP levels in acromegalic patients were significantly increased. It may be important to evaluate CHITO, AGE, and hsCRP levels in acromegalic patients who are already under cardiometabolic surveillance due to risk of developing cardiovascular disease.

Erectile Dysfunction Is Associated With Excessive Growth Hormone Levels in Male Patients With Acromegaly

Objective

To determine the risk factors for erectile dysfunction (ED) in male patients with acromegaly and to prospectively investigate the short-term changes of erectile function after surgery or medical treatment.

Methods

Sixty-three male patients were subjected to nocturnal penile tumescence and rigidity (NPTR) test for the evaluation of erectile function. The measurement of serum nitric oxide (NO) was also performed. Twenty-seven patients were re-evaluated by NPTR after surgery or long-term somatostatin analogues (SSA) treatment.

Results

Twenty-two patients (34.9%) had ED. Patients with ED showed higher random GH (17.89 [10.97-44.19] μg/L vs 11.63 [4.31-28.80] μg/L, p = 0.020) and GH nadir (GHn) (10.80 [6.69-38.30] μg/L vs 8.76 [3.62-18.19] μg/L, p = 0.044) during oral glucose tolerance test (OGTT). The NO levels of ED patients were lower than non-ED patients (9.15 [5.58-22.48] μmol/L vs 16.50 [12.33-31.78] μmol/L, p = 0.012). After treatment, patients who present improvement in erectile function showed lower post-GHn (0.07 [0.03-0.12] ng/ml vs 1.32 [0.09-3.60] ng/ml, p = 0.048) and post-IGF-1 index (1.03 ± 0.38 vs 1.66 ± 0.95, p = 0.049). The multivariate analysis indicated post-GHn was still associated with the improvement of erectile function after correction of other covariates (OR: 0.059, 95% CI: 0.003-1.043, p = 0.053).

Conclusions

Excessive GH is related to ED in male patients with acromegaly. GH normalization after treatment is beneficial for short-term erectile function recovery.

Acromegaly, inflammation and cardiovascular disease: a review

Acromegaly is characterized by Growth Hormone (GH) and Insulin-like Growth Factor 1 (IGF-1) excess. Uncontrolled acromegaly is associated with a strongly increased risk of cardiovascular disease (CVD), and numerous cardiovascular risk factors remain present after remission. GH and IGF-1 have numerous effects on the immune and cardiovascular system. Since endothelial damage and systemic inflammation are strongly linked to the development of CVD, and have been suggested to be present in both controlled as uncontrolled acromegaly, they may explain the presence of both micro- and macrovascular dysfunction in these patients. In addition, these changes seem to be only partially reversible after remission, as illustrated by the often reported presence of endothelial dysfunction and microvascular damage in controlled acromegaly. Previous studies suggest that insulin resistance, oxidative stress, and endothelial dysfunction are involved in the development of CVD in acromegaly. Not surprisingly, these processes are associated with systemic inflammation and respond to GH/IGF-1 normalizing treatment.

Enzymatic antioxidant system and endothelial function in patients with metabolic syndrome

BACKGROUND

This study examined the relationship between serum glutathione peroxidase 1 (GPx-1) activity and endothelial dysfunction in the subjects with and without metabolic syndrome (MetS).

METHODS

This case-control study was conducted on 76 subjects, 38 were patients with MetS and 38 were without MetS. The demographic, clinical, and laboratory features of the subjects were measured and then compared. The MetS was diagnosed according to the definitions of the National Cholesterol Education Program (NCEP) and International Diabetes Federation (IDF). Serum GPx-1 activity was measured by standard methods. Endothelial dysfunction was assessed with flow-mediated dilation (FMD) technique.

RESULTS

In case-control study of 76 subjects, all of MetS risk factors including abdominal obesity, triglyceride (TG), low serum level of high-density lipoprotein cholesterol (HDL-C), hypertension (HTN), and fasting plasma glucose (FPG) were significantly higher than healthy individuals (P < 0.050). FMD was significantly lower than normal subjects (P < 0.050). Serum GP-1 activity was significantly lower in patients with MetS compared to normal subjects (21.7 ± 13.5 vs. 79.0 ± 38.6, respectively) (P = 0.001). The value of GPx-1 was significantly correlated with diastolic blood pressure (DBP) (r = -0.249, P = 0.040), C-reactive protein (CRP) (r = -0.409, P = 0.014), and FMD (r = 0.293, P = 0.050) in patients with MetS. The results of logistic regression showed that a unite increase in CRP (mg/dl), FMD (%), and endothelin-1 (ET-1) (pg/ml) and a unit decrease in GPx significantly increased the odds ratio (OR) of MetS; after adjusting for age and sex the results remained significant except for FMD (P < 0.050)

CONCLUSION

Endothelial dysfunction is related to serum GPx-1 activity in patients with MetS. GPX-1 activity is associated with risk of cardiovascular diseases (CVDs) and peripheral vascular diseases (PVDs) in patients with MetS.

The Endothelium in Acromegaly

Growth hormone (GH) and insulin like growth factor-1 (IGF-1) excess induce well-known deleterious effects on the cardiovascular system, especially after long-term exposition. Acromegaly, a condition of chronic GH and IGF-1 hypersecretion, is frequently associated to cardiovascular complications, although recent studies have shown a reduction in the prevalence of these comorbidities in well-controlled patients and a mortality risk similar to normal aging population. Many factors could contribute to the increased cardiovascular risk of acromegaly patients. Among these factors, the endothelium plays a key role in the pathogenesis of atherosclerotic plaques and could be considered an early marker of atherosclerosis and cardiovascular dysfunction. In this review we examined the relationship between GH/IGF-1 excess and the endothelium, from basic studies to clinical evidence. Many studies involving various arterial districts (microvascular arteries of retina, kidney and brain, and major vessels as carotid and aorta) showed that GH/IGF-1 excess promotes endothelial dysfunction via several different mechanisms. Increased endothelial proliferation, dysfunction of endothelial progenitor cells, increased oxidative stress, and compromised oxidative defenses are the main factors that are associated with endothelial dysfunction. In the general population, these alterations are associated with the development of atherosclerosis with an increased incidence of coronary artery disease and cerebrovascular complications. However, in acromegaly this is still a debated issue, despite the presence of many pro-atherogenic factors and comorbidities, such as hypertension, diabetes, sleep apnoea, and metabolic syndrome. Preclinical markers of atherosclerosis as arterial intima media thickness, pulse wave velocity and flow mediated dilation seem to be impaired in acromegaly and partly mediated by the endothelium dysfunction. In conclusion, the pathophysiology of endothelial dysfunction in the condition of GH and IGF-1 excess remains a crucial area of investigation to fully dissect the association of acromegaly with cardiovascular disease complications.

Bringing Cardiovascular Comorbidities in Acromegaly to an Update. How Should We Diagnose and Manage Them?

Patients with acromegaly frequently develop cardiovascular comorbidities, which significantly affect their morbidity and contribute to an increased all-cause mortality. In this regard, the most frequent complications that these patients may encounter include hypertension, cardiomyopathy, heart valve disease, arrhythmias, atherosclerosis, and coronary artery disease. The specific underlying mechanisms involved in the pathophysiology of these comorbidities are not always fully understood, but uncontrolled GH/IGF-I excess, age, prolonged disease duration, and coexistence of other cardio-vascular risk factors have been identified as significant influencing predisposing factors. It is important that clinicians bear in mind the potential development of cardiovascular comorbidities in acromegalic patients, in order to promptly tackle them, and avoid the progression of cardiac abnormalities. In many cases, this approach may be performed using straightforward screening tools, which will guide us for further diagnosis and management of cardiovascular complications. This article focuses on those cardiovascular comorbidities that are most frequently encountered in acromegalic patients, describes their pathophysiology, and suggests some recommendations for an early and optimal diagnosis, management and treatment.

Short-term, supra-physiological rhGH administration induces transient DNA damage in peripheral lymphocytes of healthy women

PURPOSE

While a good safety for recombinant human growth hormone (rhGH) therapy at replacement doses is recognized, a possible link between high concentration of the GH-IGF-I axis hormones and side negative effect has been reported. The aim of this pilot study was to assess whether a short-term exposure to supra-physiological doses of rhGH may affect DNA integrity in human lymphocytes (PBL).

METHODS

Eighteen healthy Caucasian female (24.2 ± 3.5 years) were randomly included in a Control (n = 9) and rhGH administration group (n = 9, 3-week treatment). DNA damage (comet assay), chromosomal breaks, and mitotic index in phytohemagglutinin-stimulated PBL were evaluated before (PRE), immediately (POST), and 30 days (POST30) after the last rhGH administration (0.029 mg kg^- 1 BW; 6 days/week), together with serum IGF-1 and IGFBP-3 concentrations.

RESULTS

rhGH administration increased IGF-I, without evidence of persisting IGF-I and IGFBP-3 changes 30 days after withdrawal. Total DNA breakage (% DNA in tails) was not significantly different in subjects treated with rhGH in comparison with controls, although the rhGH-treated subjects showed an higher percentage of heavily damaged nuclei immediately after the treatment (POST30 vs. PRE: p = 0.003), with a lower mitogenic potential of lymphocytes, detectable up to the POST30 (PRE vs. POST: p = 0.02; PRE vs. POST30: p = 0.007).

CONCLUSIONS

This pilot study showed that 3 weeks of short-term supra-physiological rhGH administration in healthy women induce a transient DNA damage and mitogenic impairment in PBL. The analysis of DNA damage should be explored as useful tool in monitoring the mid to long-term effects of high rhGH treatment or abuse.

Serum paraoxonase level and paraoxonase polymorphism in patients with acromegaly

BACKGROUND

Acromegalic patients have increased cardiometabolic risk factors due to an elevation of growth hormone (GH) levels. Human serum paraoxonase (PON), a high-density lipoprotein (HDL)-related enzyme, is one of the major bioscavengers and decreases the oxidation of low-density lipoprotein (LDL), a key regulator in the pathogenesis of atherosclerosis. In this study, we investigated a potential relationship between serum PON levels or PON polymorphisms and acromegaly.

METHODS

A total of 48 acromegalic patients and 44 healthy controls were included in this study. Serum GH levels, insulin-like growth factor-1 levels and lipid profiles were measured. Serum PON levels, as well as PON 1 L55M and Q192R gene polymorphisms, were examined.

RESULTS

No significant differences were found in terms of age, gender, presence of diabetes, serum LDL cholesterol (LDL-C), HDL-C, or triglyceride levels between the case and control groups (P > 0.05). A statistically significant difference was found in serum PON levels between the cases and controls (P = 0.007). The median serum PON level was 101 ± 63.36 U/l in the case group and 63 ± 60.50 U/l in the control group. There was a significant correlation between serum PON levels and IGF-1 levels (P = 0.004, r = 0.319); however, no significant differences were found in PON1 L55M and PON Q192R polymorphisms between the patients and controls (P = 0.607 and P = 0.308, respectively). In addition, no significant differences were found in serum PON levels in acromegalic patients who were and were not in remission (P = 0.385), nor between those with PON1 L55M and Q192R polymorphisms (P = 0.161 and P = 0.336, respectively).

CONCLUSIONS

Elevated serum PON levels were detected in acromegalic patients, independently of their remission status. This suggests protective effects for cardiometabolic risk parameters.

Markers of early atherosclerosis, oxidative stress and inflammation in patients with acromegaly

PURPOSE

Data regarding atherosclerosis in acromegaly is controversial in literature. We aimed to investigate the markers of early atherosclerosis, oxidative stress, inflammation and their relationships with each other in acromegaly.

METHODS

Thirty-nine patients with acromegaly and 40 control subjects were enrolled. Patients were classified into two groups; active acromegaly (AA) and controlled acromegaly (CA). Controls were matched by age, gender, body mass index and presence of cardiovascular risk factors. Flow mediated dilatation (FMD), carotid intima media thickness (CIMT), epicardial adipose tissue thickness (EAT) were measured and serum levels of oxidative stress parameters, high mobility group box 1 protein (HMGB1) and high sensitive CRP (hs CRP) were evaluated.

RESULTS

Significantly decreased FMD, increased CIMT and EAT were found in patients with acromegaly compared to controls (p < 0.01, p < 0.05, p < 0.001, respectively). EAT correlated negatively with FMD (r = -0.24, p = 0.038) and positively with CIMT (r = 0.37, p < 0.01). Presence of acromegaly, hypertension and age were found to be the predictors of early atherosclerosis (p < 0.05). Hs CRP was decreased in AA compared to controls (p = 0.01). There were no significant differences for HMGB1 and oxidized LDL (ox-LDL) cholesterol levels and total antioxidant capacity (TAC) between AA, CA and controls (p > 0.05).

CONCLUSION

Early atherosclerosis measured with FMD, CIMT and EAT may exist in acromegaly. However, decreased hs CRP and unchanged HMGB1, ox-LDL and TAC levels suggest that inflammation and oxidative stress do not seem to contribute to the development of atherosclerosis in these patients.