Determining the response of plasma CRP and IL-6 levels to a morning and evening activity session

1-1- Introduction

Cardiovascular disease (CHD) [1] and on top of that coronary artery problems are one of the main causes of death in the new century and the first causes of death in Iran. High blood pressure, high blood fats and lipoproteins, age, sex, lifestyle, nutrition, smoking, inactivity, diabetes and obesity are among the traditional risk factors of cardiovascular diseases (Thalathi et al., 2016). Oxidative stress, inflammation, endothelial cell activity, and platelet activity are other new risk factors for cardiovascular disease (Boyukazi [2] et al., 2007).  So far, many studies have been conducted to identify the best indicator or predictor of this disease.  In the meantime, people have been observed whose traditional risk factors (especially blood lipoproteins) are within the normal range, but they have suffered cardiovascular complications. Although the increase of low-density lipoprotein (LDL-C) [3] and the decrease of high-density lipoprotein (HDL-C) [4] are the main indicators and risk factors of cardiovascular diseases, 50% of all heart muscle infarctions occur among people without high blood lipids (Boyokazi et al., 2007). Therefore, researchers are looking for indicators that more accurately and sensitively predict the risk of cardiovascular diseases. In 1998, the American Heart Association convened a conference to identify strategies to help people who need primary prevention. One of these proposed solutions was the measurement of inflammatory indices (Gefken[5], 2001). Since then, a lot of research has been done and it has been accepted that the spread of cardiovascular diseases has an inflammatory background and that general (systemic) inflammation plays a central role in the development and progression of atherosclerosis [6] (Gefken, 2001 and Blake [7], 2001). Therefore, in the last decade, researchers have paid more attention to inflammatory indicators as independent predictors of cardiovascular diseases. Today The relationship between inflammation and atherosclerosis (the most important cause of coronary artery disease) has been revealed during many studies (Nakajima [8], 2007; Debidi Roshan et al., 2015; Hamedi Nia et al., 2015). Researchers have found that inflammatory indicators (such as fibrinogen, adhesion molecules [9], amyloid A, serum interleukin [10] and acute phase proteins) can predict suitable for cardiovascular diseases (Verdt [11] et al., 2004). Various studies show the relationship between the risk of cardiovascular disease and inflammatory indicators (Hammer [13], 2004). Among these inflammatory indicators, C-reactive protein (CRP) [14] has a special feature It is a measure that this ability is less seen in other inflammatory indices. CRP is one of the most sensitive markers of inflammation and the strongest predictor of cardiovascular disease (J. Hage[15] et al., 2007; Verdet et al., 2004; Pakzek et al., 2005). Interleukin 6 is also one of the inflammatory indicators and predictors of cardiovascular disease. Increased serum levels of CRP and IL-6 are related to increased risk of cardiovascular disease. New studies have shown that in predicting cardiovascular events, CRP is a stronger index than LDL-C, so that an increase in this index predicts the future risk of plaque rupture (Namazi et al., 2019). On the other hand, many studies have reported the relationship between CRP and IL-6 changes (Hamdinia et al., 2015). IL-6 serum levels are increased under the influence of obesity, diabetes, cardiovascular disease and metabolic syndrome and stimulate the synthesis of serum CRP from the liver. In addition to the mentioned cases, exercise and physical activity is one of the effective factors on serum CRP and IL-6 concentration, which causes different changes under the influence of intensity and duration of activity. It seems that long-term and intense sports reduce the body's capacity to deal with free and active oxygen radicals and can cause oxidative stress, while moderate-intensity sports and exercises can increase the antioxidant capacity and physiological defense and reduce the occurrence of oxidative stress. The findings of the existing research indicate the dual nature of the immune response to exercise. Exercise and intense and long-term activities with strong outward contractions and with high mechanical stress cause muscle damage and can cause the release of cytokines (Namazi et al.T. Hong[16] et al. (2009) with a study on 13 men aged 21.5 ± 1.8 years old who performed an exercise at two intensities of 65% and 85% of their maximum aerobic power; They concluded that CRP levels increased significantly in both groups. Surichter [17] et al. (1995) and Malem [18] et al. (2004) showed that CRP levels do not increase significantly after outdoor exercise. On the other hand, Smith [19] and colleagues reported an increase in CRP in 75% of active untrained people, 24 hours after 60 minutes of cycling with 60% of maximal oxygen consumption. Also, Meier[20] and colleagues showed a significant increase in CRP 12 hours after performing an ergometer bicycle test by 12 trained men (cited by Semple[21], 2006). Currently, little information is available about the effect of intense aerobic exercise on cardiovascular and immune indicators. Aerobic exercise seems to have multiple effects based on intensity, duration and volume. Therefore, in an attempt to determine the effect of a single session of intense aerobic exercise on the serum levels of CRP and IL-6 in healthy young women, in the present study it is assumed that a morning and evening activity has an effect on the serum concentration of CRP and IL-6.

Atherosclerosis is a progressive heart disease that begins in childhood and occurs in old age.  It is also predicted that atherosclerosis will be the dominant disease of 2020, so the prediction of coronary heart disease (CHD) is very important in the treatment and prevention of disease progression (Turk [22], 2004). According to extensive studies, the American Heart Association has declared that the spread of cardiovascular diseases has an inflammatory basis and general inflammation plays a central role in the development and progression of atherosclerosis. For a long time, fat profile has been considered as an indicator of cardiovascular diseases, but reports show that some people with normal HDL-C and LDL-C are affected by cardiovascular diseases, so the attention of researchers has been directed to indicators that more accurately predict the risk of cardiovascular disease. Some of these indicators include fibrinogen, coagulation factors 8 and 9, adhesion molecules, serum amyloid A, cytokines, especially IL-6 and CRP. Among these inflammatory indicators, CRP has a special feature. CRP was discovered by Tillet [23] (1930) and Francis [24] (1930) found that CRP is the first acute phase reactant during his studies in pneumonia patients. Human CRP consists of 260 non-covalently linked amino acids with homologous order around a central pore (J. Hage et al., 2007). The plasma level of CRP is related to obesity, insulin resistance, diabetes, metabolic syndrome, age and physical exercise (Dobidi Roshan et al., 2014; Hamedi Nia et al., 2015; Jay Hage et al., 2007). IL-6 is also one of the risk factors of cardiovascular disease (Verdet et al., 2004; Tahiri et al., 2016). IL-6 is a polypeptide compound that is secreted from activated monocytes, macrophages, fibroblasts, and endothelial cells and adipocytes in response to various stimuli such as bacterial endotoxins, physical exercise, tissue damage, and oxidative stress (Paczak[25] et al., 2005). Plasma levels of IL-6 are also related to obesity, diabetes, metabolic syndrome, exercise and age (Thalashi et al., 2016). Also, IL-6 plasma levels are related to fasting insulin and blood pressure (Anderson [26] et al., 2009). IL-6 is a cytokine with different functions that affects many tissues and cells. One of its most important effects is the stimulation of CRP production (Agha Alinejad and Shamsi, 2019). It was said earlier that blood lipid profile (LDL-C, TG, HDL-C) is also one of the traditional risk factors of atherosclerosis.   A common concept surrounding the pathophysiological mechanism of inflammation associated with atherosclerosis is the production of cytokines associated with inflammation in response to the stimulus of oxidized LDL and macrophages associated with atherosclerotic plaques (Thalathi et al., 2016). Basak et al (2004) stated that there is little correlation between CRP and lipoproteins. Several studies have shown that the risk of high CRP is independent of the amount of blood lipids (Thalathi et al., 2016). It seems that how inflammatory markers change is greatly influenced by the type, intensity and duration of exercise. Fioti [27] et al. (1999), conducted a study on peripheral vascular patients.