This was a prospective and cross-sectional study carried out in the Functional Physiology and Exploration Department of the Faculty of Medicine, Pharmacy and Odontology (FMPO) of the University of Cheikh Anta Diop (UCAD) in Dakar / Senegal from April to July 2017.
Each subject, after an interrogation and a complete physical examination of all devices and systems, had undergone a take of his anthropometric parameters, clinical constants and an assessment of his overall body and abdominal fat. Then we measured the arterial stiffness using a pOpmeter device. Thus each subject was terminated by evaluation of the endothelial function using an EndoPAT2000 device. The protocol was created according to the recommendations of the Helsinki declaration and approved by the FMPO / UCAD Ethics Committee.
Assessment of overall and abdominal body fat It was carried out by an Omron brand bio-impedancemeter. The weight to the nearest gram and the size to the nearest centimeter were taken beforehand and typed on the keyboard of the device as well as the age and sex of the subject. All of this data is needed to obtain results from the predictive equations inserted into the device's memory.
The person climbs on the scale by placing his bare feet on marks (electrodes). To limit possible variations in body fat, the subjects were weighed under the same conditions during the same morning and fasted. The reference values were taken according to the recommendations of Moreno MV. of 2007 and Oliveira EP. of 2011 [13,14]. The body fat index was calculated according to the Deurenberg formula .
Measurement of systolic arterial pressure (SBP) and diastolic blood pressure (DBP) was performed by an Omron electronic sphygmomanometer with cuff adapted to the subjects' arms. This decision was made respecting the required conditions. According to the WHO, hypertension (HTA) was considered effective when the systolic blood pressure (SBP) was greater than or equal to 140mmHg and / or the diastolic blood pressure (DBP) was greater than or equal to 90mmHg.
Mean arterial pressure (MAP) was calculated according to the formula of Messai E. Ed. Arnette Blackwell (Paris) 1995: MAP = DBP + (SBP - DBP) / 3. The heart rate was measured with the blood pressure monitor at the same time as the arterial pressures. Evaluation of arterial stiffness.
The arterial stiffness parameter than we chose was the rate of propagation of the finger-toe pulse wave (PWVft). It was measured rapidly, reproducibly and non-invasively by a pOpmeter (Axelife SAS, France). According to the recommendations of Hallab M, et al. .
We did two measurements for each patient and then took the mean of the two measurements. The higher the value of this PWVft, the greater the rigidity of the artery.
Evaluation of endothelial function
The parameter of the endothelial function we had chosen was peripheral arterial tone. It is a parameter that reflects endothelial responsiveness. It was evaluated using a device called EndoPAT2000. During the measurement, the patient was supine on an examination table in a quiet, well-lit room. The measurements were made according to the recommendations of Goor DA, et al. The normal values of the Hyperhemic Reactivity Index (HRI) and its logarithm (LnHRI) are (1.67 to 2) and (0.51 to 0.70) respectively. A HRI value below 1.67 can therefore be considered as evidence of endothelial dysfunction .
Evaluation of the biological parameters
The biological parameters were measured the same day in the laboratory of biochemistry of the FMPO / UCAD of Dakar / Senegal. The takings were made at 8 am in the morning after a fat of at least 12 hours (am). Some venous blood was taken at the level of the fold of the elbow of the not dominant arm.
So on fluoride tube we measured the fasting blood sugar, on heparine tube we measured lipids (Cholesterol Total, HDLCholesterol, LDL-Cholesterol and Triglycerides). By enzymatic method, we measured the fasting blood sugar, the Total Cholesterol, the HDL- Cholesterol, the LDL-Cholesterol, the Triglycerides.
All variables were saved in an Excel table. The exploitation of the data was carried out thanks to SPSS software version 16.0 Quantitative variables were described using mean +/- standard deviation and qualitative variables using absolute values and percentages. The unpaired student T test was used to compare the means of the quantitative variables. Correlation tests and linear regression tests were conducted to investigate relationships between segmental or global accumulation of body fat and the presence of vascular dysfunction.
The results are considered significant when p <5%.
Characteristics of the study population : The mean age of the study population was 41.94 years +/- 8.82 (with extremes of 26 and 60 years). In the study population, 2 subjects (11% of subjects) were hypertensive known and monitored. None of the subjects was athletic or smoking and there were no diabetic or dyslipidemic subjects either. None of the subjects in the study had multiple autoimmune disease or antiphospholipid antibody syndrome. We found that 4 of the subjects (19.05%) had a positive immunological status and these were antiScl70 in 75% of cases. The mean duration of disease progression was 62.14 months +/- 13.65, and that of Raynaud's phenomenon was 62.56 months +/- 28.84. The characteristics of scleroderma in the study population are presented in Table 1.
Study of anthropometric parameters and body fatness:
Of the subjects, 38.89% were overweight according to BMI while 55.56% were overweight according to body fat percentage. The leanness was 11% of subjects according to BMI and 16.67% according to the percentage of body fat. By the Fat Mass Index, the 55.56% were also too fat and they were not all in the category of excess weight according to body fat. According to the WS and the WS/ HC ratio, abdominal obesity accounted for 27.78% and 38.89% of the study population, respectively, while in the normal range, visceral fat level was the study. However 44.44% of the subjects had a level of visceral fat greater than 5 (Table 2).
Study of cardiovascular constants and vascular function :
We found that 4 of the subjects (22.22%) were considered hypertensive with either elevated SBP and / or DBP. The MBP was elevated also in 22.22% of subjects. In addition 75% of hypertensive subjects were in the overweight category according to the percentage of body fat. The heart rate (HR) was normal in all subjects. Accelerated PWVft was noted in 94.44% of subjects while HRI was abnormal in 45.5% of subjects (Table 3).
Comparison of means of anthropometric parameters and adiposity as a function of cardiovascular constants : We noted that among the vascular parameters, only the presence of HTA was significantly different depending on the overall and abdominal adiposity. It is noted in the table 4. We found positive correlations between vascular parameters and overall and abdominal adiposity (Table 5). We also found a positive correlation between MBP and Fast blood sugar (p = 0.04 r = 0.56) but also a negative correlation between SBP and HDL-Cholesterol (p = 0.03 r = -0.58). We also found strong positive correlations between Fast blood sugar and anthropometric parameters and body fatness (Table 6) Study of associations after linear regression : After linear regression testing we found that the parameters that tended to be independently influencing the SBP were age (p=0.01), FMI (p=0.014) and HDL-cholesterol. At the same time, the only parameter that tended to affect the HRI was the HR (p=0.01).
This cross-sectional and prospective study was conducted to evaluate changes in the amount and distribution of body fat and their implications for the occurrence of cardiovascular events during systemic sclerosis in black Senegalese women. It could contribute to the evaluation of the prognosis of this disease. We had been limited by the calibration of bio-impedancemeter, pOpmeter and EndoPAT that could not evaluate the subjects too lean.
We only included in this study female subjects with a mean age of 41.94 years +/- 8.82. Like most connective tissue diseases, systemic scleroderma is unique to the young woman of childbearing age, the woman between 45 and 64 . We found that 38.89% of the population was overweight according to BMI and 55.56% were according to Percentage of Fat Mass. By the Fat Mass Index, we noted that the 55.56% of subjects were also too greasy.
According to WS and WS / HC, abdominal obesity was 27.78% and 38.89% of the study population, respectively. The WS plus WS / HC ratio estimates intra-abdominal fat that can be divided into perivisceral and / or subcutaneous fat. The level of visceral fat is normal whereas the WS and WS / HC ratio were high in our subjects that would be in favor of an excess of subcutaneous fat . Many cross-sectional studies have indicated that the specific increase in the amount of peri-visceral intra-abdominal fat is more strongly associated with different metabolic syndrome abnormalities than subcutaneous intra-abdominal fat . Whatever the method used, a considerable adiposity, overall and abdominal, was noted in our sclerodermic subjects.
In our study population, 4 subjects (22%) were hypertensive despite their systematic use since diagnosis with inhibitors of the conversion enzyme (ICE) and calcium inhibitors (CI). In fact, ICE are often prescribed in high doses in order to control blood pressure and obtain systolic blood pressure ≤ 120 mmHg and diastolic blood pressure ≤ 80 mmHg . Indeed, hypertension is the main prognostic factor for the occurrence of a scleroderma kidney crisis , and that CIs are indicated in the management of Raynaud's phenomenon [23-25]. In addition 75% of hypertensives are in the overweight category according to the level of visceral fat. At the same time, the HTA was significantly more present in the group of subjects whose percentage of body fat was higher (p=0.006), the level of visceral fat was higher (p˂0.0001) and the fat mass index was greater (p=0.01). There were also positive correlations between SBP with BMI (p=0.04 r=0.48), VFL (p=0.02 r=0.54) and FMI (p=0.01 r = 0.59); between DBP with FMI (p=0.03 r=0.51) but also between MAP with VFL (p=0.02 r=0.54) and FMI (p=0.01 r=0.59). These findings would reflect close links between vascular parameters and overall and abdominal adiposity in our sclerodermic subjects. The relationship between abdominal adiposity and cardiovascular risk has been described in numerous epidemiological studies . Cardio-metabolic complications associated with abdominal obesity (high blood pressure, type 2 diabetes and atherogenic dyslipidemia) may be partly responsible for increased cardiovascular risk .
An accelerated PWVft was noted in 94.44% of subjects, which would be in favor of a high arterial stiffness in our patients. The only subject whose PWVft was normal, was a normal WS, a normal WS / HR ratio and a normal total body fat percentage. Among high PWVft subjects, the 56% had excess body fat. Measurement of pulse wave velocity (PWV) provides an estimate of arterial stiffness, a likely early marker of preclinical disease. The simplicity and the good reproducibility of these measurements explain that they have become in recent years, a privileged tool of epidemiological research in the cardiovascular field . In contrast, only a few studies have analyzed the relationships between body composition and vascular wall structure. The Amsterdam Growth and Health Longitudinal Study (AGHLS) found no association between fat mass (measured by DEXA) and intimal media thickness (IMT). But previous Japanese studies have established an association between subcutaneous fat, visceral fat and intima-media thickness (IMT) [28-30].
In addition to other work have shown that some anthropometric parameters were positively associated with vascular structural parameters. Abdominal fat distribution (increased WS / HR ratio or WS) would be associated with the development of atherosclerotic pathologies. Studies have shown a significant association between the EIT and the BMI  as we noted during systemic scleroderma.
The HRI was abnormal in 45.5% of subjects, which means that almost half of the subjects in the study had endothelial dysfunction. Alteration of endothelial function during scleroderma has been reported by previous studies . Endothelial dysfunction is a keyelement in the pathophysiology of systemic sclerosis and affects the majority of scleroderma patients . Endothelial dysfunction is an alteration of the vessel's ability to endothelium-dependent dilation in response to a stimulus. During scleroderma, functional and structural changes occur primarily within microvessels but also in larger vessels. Szucs G, et al. have confirmed the alteration of endothelial function of macrovessels in scleroderma . It is well established that endothelial dysfunction is the most important step in early atherogenesis and also contributes to the development of atheromatous plaque progression in later stages of vascular injury. Peripheral involvement in scleroderma is thought to be related to various abnormalities of neuro-endothelial control mechanisms, distal vascular structure abnormalities and intravascular factors such as pro-coagulation and increased oxidative stress. Endothelial injury is essentially an occlusion of light resulting in tissue hypoxia. A positive correlation was noted between endothelial dysfunction and heart rate (p=0.03 r=0.65). Endothelial cells lining the luminal surface of blood vessels play a key role in regulating vascular homeostasis primarily through the formation of potent vasodilator factors such as nitric oxide (NO). The formation of these factors is stimulated by many stimuli such as shear forces. During endothelial dysfunction, the bioavailability of NO would be in deficit  and this results in systemic vasoconstriction which would further increase the effects of shear forces. These are the result of the ejection of blood into the vascular system by the heart and clinically reflected by the heart rate, which could explain the links between endothelial dysfunction and heart rate in our study.
In fact, the relationship between abdominal adiposity and cardiovascular risk has been described in many epidemiological studies . Obesity has been shown to be associated with increased mortality and cardiovascular risk, and the risk depends, in part, on the effect of obesity on known cardiovascular risk factors (dyslipidemia, high blood pressure, diabetes) but also an effect on new markers of risk of recent discovery (thrombotic, inflammatory). The development of cardiovascular complications depends not only on the degree of excess weight, but also on the delay in gaining weight over the course of life, the distribution of adipose tissue, the associated vascular risk factors, and the consequences of physical inactivity. The mechanisms involved are complex and intricate with the intervention of hemodynamic and metabolic factors . Hemodynamic adaptations are determined by changes in body composition resulting in a state of hypervolemia that will over-solicit the heart of the obese subject. When these adaptations are exceeded, a left ventricular hypertrophy (LVH) develops in the context of a cardiomyopathy specific to obesity. The corpulence could also induce development of coronary artery disease independently of other risk factors . Be that as it may, many prospective studies with prolonged follow-up have shown a direct link between overall adiposity and coronary risk . The pathophysiology of macrovascular systemic sclerosis is poorly understood but may be related to several factors including cardiovascular risk factors, endothelial activation, and disease-specific factors .
In our study we noted a negative correlation between cholesterol level with WS / HC ratio (p=0.002 r=-0.75) and (p=0.03 r=-0.58). Then an increase in abdominal adiposity would cause a decrease in the blood level of HDL-cholesterol with consequent increase of the SBP. Some studies have shown that biomarkers of atheromatous risk were abnormal in scleroderma patients such as lipid profile or LDL-cholesterol . The formation and structure of HDL may be altered in an inflammatory context, thus losing its cholesterol transport capacity and its antioxidant activity . This form of HDL could even become proinflammatory (piHDL) and contribute to oxidative stress .
A detectable level of HDL-proinflammatory has been associated with an increased risk of atherosclerosis in patients followed for systemic and chronic inflammatory autoimmune disease [42,43]. In a study of 17 scleroderma patients compared to a group of matched patients, 5 scleroderma patients (29%) had detectable HDL- proinflammatory levels against no controls (p = 0.006) .
In terms of LDL-cholesterol, oxidation of LDL plays a role in the pathogenesis of atherosclerosis . A higher level of oxidized LDL has been found in the plasma of scleroderma patients . In our study, the mean LDL level was 1 g/L and only 15% of patients were treated with statin.
Adipocytes are able to secrete conventional pro-inflammatory cytokines such as TNF alpha and IL-6 . Other molecules specifically secreted by adipocytes share this regulator function of inflammation, those are adipokines such as leptin, adiponectin, resistin and visfatin . In patients with increased adipose tissue and thus fat mass, a low-intensity chronic inflammatory state is present with a large increase in plasma concentrations of TNF alpha and IL-6 . The serum concentration of CRP is also greatly increased and is correlated with BMI .
Systemic scleroderma is an autoimmune, chronic inflammatory disease characterized by a decrease in life expectancy due mainly to cardiovascular events. Involvement of vessels of all sizes would play a fundamental role in the morbidity and mortality noted in this disease. It would be among the first alterations during the disease. An accumulation of body fat would be involved in the occurrence of structural and functional alterations of the vessels during this disease.
Conflicts of Interest
The authors thanks the UMI3189 "Environnement, Sante, Societes" for its financial support to this research.