A Cross-Sectional study to evaluate the levels of troponins, apolipoproteins, adipokines, insulin and vanillylmandelic acid in hypertensives attending clinic at Federal University Teaching Hospital, Owerri was carried out. A total of subjects comprising 104 hypertensives (54 males, 50 females) on treatment, 52 hypertensives not on treatment and 52 normotensives who served as control and within the ages of 25 and 72 years were recruited for the study. Interleukin-6 (IL-6) and Tumor Necrosis factor-alpha (TNF-α) were determined using Enzyme linked immunosorbent assay techniques. All kits were commercially purchased and the manufacturer’s standard operational procedures were strictly followed. Data was analyzed using the software statistical package for social sciences version 21, windows 9, values were expressed as mean ± standard deviation, student t-test and analysis of variance were used to analyze the difference in experimental variables, Results showed that there were significant lower levels of IL-6 (8.94 ±1.96) and TNF-α (11.73 ±3.46) in hypertensive on treatment compared to hypertensive not on treatment (12.94 ±1.96, 16.96 ±10.61) (p<0.05). There was a significant progressive increase in TNF-α from age range 25-37 years (4.06 ±2.04) to age range 64-72 years (13.32 ±1.73) (p<0.05). From the findings, the inclusion of  Interleukin-6 (IL-6) and Tumor Necrosis factor-alpha (TNF-α)  in the routine laboratory investigations of conditions related to obesity, myocardial infarction, coronary heart disease, artherosclerotic disease, dyslipidaemia, vascular hypertrophy and other complications of hypertension in these patients will be useful in the prediction, management and risk assessment of this disease and may subsequently improve treatment outcome.

Hypertension is one of the major public health problems as well as the most significant risk factors of morbidity and mortality worldwide [1]. This can be attributed to its associated risk damage to vital body organs like the brain, heart and kidneys (Bavishi et al., 2016). Nigeria, a developing country in West Africa has not been spared by the global epidemic of hypertension and this is associated with alarming rate of obesity, physical inactivity, diabetes, increased salt consumption amongst Nigerians [2]. A worldwide data to ascertain the global burden of hypertension has revealed that a total of 72 million (26.4%) were reported living with hypertension globally and with a danger of increasing to 1.56 billion in 2025 [3]. Africa has the highest prevalence of hypertension with an overall prevalence of 46% in adults aged 25 years and above for both sexes. Nigerian adults however shared an estimated prevalence of 28.9% with a range of 6.2-48.9% for the men and 10-47.3% for women as well as 30.6% and 26.4% among urban and rural dwellers respectively[4]

The etiology of hypertension is multi-factorial. Genetic factors, behavioural and socio-economic factors can put an individual at risk. Metabolic risk factors such as obesity, diabetes mellitus, raised blood lipids can also contribute to hypertension development and complications. Hypertension also is a disease related to risky behaviour such as smoking, poor diet, overweight, alcohol consumption, physical inactivity and occupational lifestyle[5]. Some risk factors like smoking diet and overweight are modifiable while some like old age and genetic predisposition are not modifiable. Hypertension is a major risk factor for coronary heart disease, ischemic and hemorrhagic stroke, heart failure, blindness, kidney disease as well as peripheral vascular disease [6]

Cytokines produced by the innate and adaptive immune systems contribute to the pathogenesis of hypertension by modulatory renal function. Hypertension is associated with chronic low-grade systemic inflammation characterized by the presence of various pro inflammatory cytokines [7]. Perturbations in immune system and chronic low grade systemic inflammation is one of the contributors in the development of hypertension. Inflammation plays a vital role in preserving physiological homeostasis of organism in protection against invading agents. On the other hand, chronic inflammation can cause tissue damage and contribute to the development and persistence of many diseases [8].  Chronic low grade systemic and unresolved smoldering chronic inflammation that is clearly indicated by increase in serum levels of inflammatory mediators like interleukin 6 and which also involves a large number of pro-and anti-inflammatory mediators like tumor necrosis factor and IL-IB [9]. An association between hypertension and inflammation has been clearly demonstrated while it is not clear whether inflammation is predominantly a cause or an effect of hypertension [10]. Tumor necrosis factor- alpha is an adipokine and a cytokine and also a constituent of pro-inflammatory cytokines that are associated with salt sensitive hypertension and related renal injury [11]. Interleukin 6 {IL-6}is also a pro-inflammatory cytokine as well as an adipokine produced by various cells including macrophages, lymphocytes, endothelia cells, vascular smooth muscle cells. Human data has shown that IL-6 is an independent risk factor for hypertension in otherwise healthy subjects.               

Hypertension is a major public health concern and a global health burden. It is therefore an important area of research due to its high prevalence and for being a high risk factor for cardiovascular diseases and many other complications such as its associated risk of damage to vital body organs like the brain, heart and kidneys [12].. Despite the use of antihypertensive drugs, lifestyle modifications and strategies for blood pressure control, a large number of hypertensive patients have remained undiagnosed, untreated or their blood pressure has remained uncontrolled to target level [13]. Also the proportion of hypertensive individuals that got treatment (55.6% in high income countries, 29.0% in low and middle income countries) and those that got their blood pressure controlled (28.4% in high income countries 10.3% in low and middle income countries) is astonishingly low. Also 40% of patients with hypertension fail to achieve adequate blood pressure control even when prescribed a combination of drugs from three or more classes [14]. These observations explain the lack of efficacy of the current hypertension prevention and control strategies and also indicate that in some patients, additional drives of hypertension must be in existence and the need for new targets to be identified for the treatment and management of hypertension to prevent complications like myocardial infarction, nephropathy, stroke and also pre-mature deaths.

Study Area

The study was carried out in the Cardiology unit of Federal Teaching Hospital, Owerri. It is a tertiary health institution involved in providing medical care to individuals with hypertension and is located along Orlu road in Owerri Municipal, Imo state. 

Owerri is the capital of Imo State in South Eastern Nigeria and the indigenous ethnic group is Igbo. Its geographical coordinates are 5.48o North latitude, 7.08o East longitude and 150 meters above sea level. Owerri is rich in Agricultural land and has quite a number of restaurants, fast food centres, hotels, schools, markets, churches and a few industries. Owerri has many professionals, artisans, skilled and unskilled man power and there are differences in their nutritional and social lifestyles.

Subject Selection and Selection Criteria

One hundred and four (104) subjects of both sexes between the ages of twenty- five to seventy -two years and who had blood pressure of 140/90 or above for more than a week and who have been attending the hypertension clinic of Federal University Teaching Hospital, Owerri for not less than three months was recruited for the study.  Test subjects were also presently on anti- hypertensive drugs only.

Fifty- two (52) hypertensive subjects who were not on anti -hypertensive drugs and 52 normotensive subjects who were staff of the hospital and whose blood pressures were below 130/80 for three weeks served as the control group.  

Inclusion Criteria

The subjects were selected based on the criteria that:

• They were hypertensive subjects who have been attending clinic for at least three months and are presently on antihypertensive drugs.
• They met the World Health Organization Criteria of Systolic blood pressure of 140 and above and diastolic blood pressure of 90 and above for two consecutive times.
• The were within the age of twenty -five to seventy- two years.
• They gave consent.

Exclusion Criteria

The study excluded:

• Those who refused to give consent.
• Those who are hypertensive and severely ill.
• Pregnant women.
• Those subjects below twenty- five years and above seventy -two years of age.
• Those who are hypertensive but have not attended clinic for up to three months.
• Alcoholics, smokers and those on any other type of medication.

Study Design

The study was a cross-sectional study and was carried out in phases, viz:

Blood Pressure Measurement

This was carried out using Omron M3 upper arm blood pressure monitor cuff sphygmomanometer (country code 25975) with the help of a clinical nurse. The cuff was placed smoothly and snugly around the upper left arm at the same vertical height as the height while seated with the arm supported. The cuff was inflated until the artery is completely occluded. With the help of a stethoscope listening to the brachial artery the pressure in the cuff was slowly released at the rate of 2mm per heart beat. As the pressure in the cuff fails a whooshing sound was heard. When blood flow started again in the artery, the beginning sound/heart beat was recorded as the systolic blood pressure. The cuff was further released until no further heart beat could be heard, this was recorded as the diastolic blood pressure. Those with systolic blood pressure of 140 and above and diastolic blood pressure of 90 and above was considered as hypertensive.

Study Parameters

The parameters that were determined included interleukin 6 (IL-6), Tumor necrosis factor -alpha (TN).

Sample Collection

a.Collection of Blood Sample

The study subjects fasted overnight within an interval of eight to twelve hours prior to collection of sample, 10ml of blood was collected aseptically from each subject by venipuncture of the antecubital vein using sterile syringe and needle. The blood sample was placed in a clean plain dry tube, allowed to clot, retracted and centrifuged at 3000rpm for 10 minutes using wisperfuge (model 1384) centrifuge (Sampson, Holland) after which the serum sample was obtained.

The serum was separated using a pasteur pipette and placed in another dry plain tube for the estimation of interleukin- 6, Tumour necrosis factor-alpha and insulin. All samples were stored at - 20oc prior to analysis.

Laboratory Procedures

All reagents were commercially purchased and the manufacturers standard operating procedures (SOPs) were strictly adhered to.

Determination of Interleukin- 6 .

This was determined using Enzyme linked immunosorbent assay technique as modified by Assay Genie (Dublin Ireland) (catalogue number HUF100180)

Determination of Human Tumor Necrosis Factor- Alpha

This was determined using Enzyme linked immunosorbent assay technique as modified by Assay Genie (Dublin Ireland) (catalogue number HUF100262)

Statistical Analysis

 Data was analyzed using software statistical package for social sciences (SPSS) version 21, windows 9.

Difference in mean values between two groups were assessed using student t-Test while difference in mean values between three groups was assessed using one- way analysis of variance (ANOVA). Pearson correlation was used to find a correlation between body mass index and blood pressure levels and levels of all parameters of hypertensive population studied.

The level of statistical significance was set at P = 0.05 (95% confidence interval). Tests with a probability value of P<0>

Keys IL - 6 = Interleukin-6, TNF-∝ = Tumor necrosis factor-alpha, n = number of samples, *= value is statistically significant at p < 0>

The mean ± SD values of Interleukin 6 (8.94 ± 1.96ng/ml) and Tumor necrosis factor-alpha (11.73 ± 3.46ng/ml) were higher which were statistically significant (p=0.001, and p=0.001) respectively in hypertensive subjects on treatment compared with the mean ± SD values (, 4.68 ± 0.76ng/ml and 4.95 ± 0.90ng/ml) respectively of the normotensive group.