Vascular disorders are one of the most important public health problems. Macrovascular diseases such as coronary artery disease, cerebrovascular disease, and peripheral artery diseases complicate and increase the chances of myocardial infarction and stroke [1] . Microvascular diseases such as nephropathy, neuropathy, and retinopathy may also result in lethal effects such as chronic kidney disorders, amputation of limbs, and loss of vision [2] . The levels of systemic vascular inflammation can be measured by the serum levels of C-reactive protein (CRP) and recent studies have proven that inflammation plays a pivotal role in the clinical pathogenesis of cardiovascular diseases. It’s hypothesized that the correlation between CRP and cardiovascular diseases is indirect, the circulating CRP is produced by the liver and can be measured as the extent of any acute phase reaction in response to a nonspecific stimulus. The elevated levels of circulating CRP are related to an increased risk of congenital heart disease, myocardial infarction, and related deaths [3] [4] [5] .

Serum amyloid A protein, fibrinogen, and CRP are some of the systemic markers of inflammation, but among them, CRP is the most promising sensitive and systemic biomarker [6] . Several prospective studies have proved that CRP can independently predict the future risk of coronary heart disease in non-diabetic subjects and have also found a two to four-fold increased risk of CHD in patients with type 2 diabetes. The early detection of high levels of CRP and identification of factors associated with increasing CRP play a crucial role in preventing severe CVD and other related vascular disorders [7] [8] .

Elevation of CRP has been shown to be associated with an increased risk for type 2 diabetes development in patients with metabolic syndrome. The risk of fatal CVD is most common among patients with diabetes. Additionally, CRP levels are shown to be associated with fatty liver irrespective of the visceral fat volume [9] . Obesity, fatty liver disease, metabolic syndrome, diabetes, cardiovascular disease, and other lifestyle-associated disorders have all been shown to have an underlying inflammatory mechanism. In this context, it is important to study how levels of hs-CRP are correlated to biomarkers of cardiovascular, hepatic, and diabetic health [10] [11] .

Traditional testing of CRP is in the range of 10 - 1000 mg/L while hs-CRP is measured in the range of 0.5 - 10 mg/L [12] . Given the association of systemic inflammation and its proven role in several chronic lifestyle diseases, we attempted to find the co-relations between this central inflammatory marker with key biomarkers of cardiovascular, diabetic, and hepatic health.

Clinical data were subjected to retrospective analysis from de-identified subjects using Java for windows version 1.8.161. Non-parametric Mann-Whitney U test was used to compare the serum levels of hs-CRP with normal and altered levels of various serum markers. Pearson’s correlation was carried out to analyze the univariant relationship between serum biomarkers with hs-CRP at p < 0.05 significance. All statistical analysis was performed using GraphPad Prism Version 7.00 and a descriptive statistic was used to define the continuous variables (mean ± SD, and median, minimum and maximum).

The baseline clinical characteristics of the study population were detailed in Table 1. The subjects were categorized based on the serum levels of various biomarkers such as cardiovascular, diabetic, and hepatic markers. Association of serum levels of hs C-Reactive proteins with selected cardiovascular, diabetic, and hepatic markers was evaluated.

Cholesterol, LDL, HDL, triglycerides, Apo A, Apo B, and lipoprotein are the vital cardio markers involved in the study. Pearson correlation analysis between the serum levels of selected cardio markers with serum levels of high sensitive C-reactive protein (hs-CRP) exhibited a positive correlation with serum levels of triglycerides (r = 0.0964, p < 0.0428) (Figure 1). The serum levels of HDL (r = −0.1423, p < 0.0027) and Apo A (r = −0.1216, p < 0.0105) (Figure 1) were found to have a negative correlation with hs-CRP (Table 2). Further, the significance of varying serum levels of lipids and lipoproteins with serum hs-CRP was studied by the Man-Whitney U test. The results showed a strong association of high levels of hs-CRP with triglycerides (p < 0.0001) (Table 3), while the high levels of hs-CRP do not have any significant impact on other cardiovascular markers.

The diabetic panel in the present study includes 6 vital markers such as insulin, ferritin, hemoglobin A1c, glucose, adiponectin, and glycated serum protein. Using Pearson correlation analysis (Table 2) among all the tested diabetic markers, glucose (r = 0.1547, p < 0.0011) (Figure 2) and glycated serum protein (r = 0.1725, p < 0.0003) (Figure 2) were found to have a strong positive correlation with circulating levels of hs-CRP. The high levels of circulating hs-CRP were found to have a strong significant association with circulating levels of insulin (p < 0.0001) by Mann Whitney U test (Table 3).

Being a hepatic origin protein, studies on the relation between the C-reactive protein and its effects on liver enzymes are surprisingly rare. The present study

highlights the association of 6 important hepatic markers as alkaline phosphatase (ALK), aspartate transaminase (AST), alanine transaminase (ALT), albumin, total bilirubin, and total protein with hs-CRP. AST was found to have a strong positive correlation (r = 0.2139, p < 0.0001) with the circulating hs-CRP (Table 2). Aspartate transaminase (AST) is the most vital phosphate-dependent

transaminase enzyme in amino acid metabolism which catalyzes the reversible transfer of a α-amino group between aspartate and glutamate. Alkaline phosphatase (r = −0.106, p < 0.0259) and serum bilirubin (r = −0.09518, p < 0.0455) were found to be weakly correlated with the hs-CRP (Table 2). The Man-Whitney U test showed a significant association of alkaline phosphatase (<0.0001) with high serum levels of hs-CRP (Table 3).

Lifestyle-associated disorders have become the bane of human health. These comorbidities such as metabolic syndrome, diabetes, etc. affect the health of the general population and leave them vulnerable to a host of diseases, the higher risk of death with SARS-CoV2 infections is a case in point [13] . Earlier detection of chronic inflammation, diabetes, and cardiovascular risk and implementation of preventive strategies would have far-reaching effects in the domain of public health [14] .

Detecting the circulating levels of various inflammatory markers such as C-reactive protein, serum amyloid A, plasma viscosity, ceruloplasmin, etc. can be an effective tool in predicting various disorders from metabolic syndrome to diabetes and cardiovascular risk [15] . In recent years, the detection of circulating levels of hs-CRP has become an effective biomarker for the prediction of a diverse class of diseases due to its accuracy, superior assay precision, and commercial availability [12] . While conventional testing measures CRP within the range of 10 to 1000 mg/L, hs-CRP is more effective in detecting inflammation at a much lower concentration ranging from 0.5 to 10 mg/L. Additionally, the existence of standards for proper calibration makes hs-CRP an analyte of choice in comparison to other existing acute phase reactants [16] . It is important to note, however, that markers of inflammation including hs-CRP are extremely nonspecific specific in nature and can be detected in various inflammatory conditions. A scientific statement by CDC/AHA reported the possible role of hs-CRP in originating atherosclerosis. An article by Life Extension magazine stated that CRP is the cause of inflammation rather than just a marker of inflammation [17] . Several reports have demonstrated hs-CRP as a strong, independent biomarker for inflammation and one of the most clinically acceptable predictors of cardiovascular risk (Emerging Risk Factors Collaboration 2010). There have been several pieces of evidence that proved the role of inflammation in various glucose-related disorders [18] [19] . The detection of inflammatory markers such as hs-CRP in the development of glucose-related disorders was found to appear in various modes of pathogenesis. For instance, antibodies against islet cells and glutamic acid decarboxylase are autoimmune inflammatory markers against β cells in nonobese adults without diabetes. Inflammatory markers such as tumor necrosis factor α, and decreased insulin sensitivity also help in predicting diabetes [20] . Various cross-sectional studies have proved elevated levels of inflammatory markers such as hs-CRP in subjects with diabetes when compared with subjects without diabetes [21] . Obesity is the most common reason for diabetes and associated cardiovascular diseases that are strongly associated with a chronic inflammatory response such as activation of inflammatory signaling pathways, uncontrolled cytokine production, and elevated levels of acute-phase reactants [22] . Similarly, metabolic syndrome includes multiple risk factors such as obesity, insulin resistance, type 2 diabetes, etc. Metabolic syndrome is associated with multiple inflammatory biomarkers such as hs-CRP, CD₄₀ ligand, interleukin-6, P-selectin, etc. WHO defines metabolic syndrome as subjects with increased cardiovascular morbidity and mortality [23] [24] . In case of both obesity and metabolic syndrome, the implication of cholesterol and other lipids on adipose tissue turns it into a major regulator of chronic inflammatory responses that, in turn, triggers adipose tissue to produce interleukin-6, tumor necrosis factor-α, and various other pro-inflammatory cytokines that are considered as chief stimulators of hs-CRP in the liver [25] . Obesity and metabolic syndrome are widely accompanied by nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) [26] . Several studies have shown the association of NAFLD and NASH with components of metabolic syndrome and it’s also characterized by the elevation of alanine aminotransferase (ALT). It could be hypothesized that the elevated levels of liver-derived inflammatory markers particularly hs-CRP might be involved in common liver abnormalities.

The present study is the first to demonstrate the association of a systemic inflammatory marker hs-CRP with three different classes of metabolic markers—cardiovascular, diabetic, and hepatic. In the current retrospective data of the healthy population, the baseline levels of hs-CRP were found to be normal in more than 50% of the population.

The data presented in the study has several diagnostic implications as hs-CRP thus far has been considered as an important marker primarily in the prediction of cardiovascular risk alone. The data presented here supports the hypothesis that hs-CRP is related to various glucose-related disorders and is also associated with altered levels of liver enzymes apart from cardiovascular disorders. This could also suggest that increased serum hs-CRP might be associated with most features of metabolic syndrome. Elevated levels of hs-CRP are independently associated with various clinical risk factors. Monitoring the circulating levels of hs-CRP might be a simple, practical, and potential tool for assessing the risk of developing cardiovascular diseases, glucose-related disorders, and liver health.

In order to access supporting data, contact the corresponding author.

We acknowledge Vibrant America LLC for supporting this research.

Hari Krishnan Krishnamurthy, Karthik Krishna, and Tianhao Wang performed the research. Hari Krishnan Krishnamurthy, John J. Rajasekaran, Karenah E. Rajasekaran, and Vasanth Jayaraman designed the study. Qi Song, Kang Bei, and Swarnkumar Reddy analyzed the data. Hari Krishnan Krishnamurthy and Swarnkumar Reddy wrote the article.

The study comprises a retrospective analysis exempted by the Western Institutional Review Board.

Hari Krishnan Krishnamurthy, Vasanth Jayaraman, Karthik Krishna, Tianhao Wang, Kang Bei, and John J. Rajasekaran are employees of Vibrant Sciences LLC. Swarnkumar Reddy, Qi Song, and John J. Rajasekaran are employees of Vibrant America LLC. Vibrant America is a commercial diagnostic lab that could benefit from increased testing of micronutrients and cardiovascular biomarkers.

Krishnamurthy, H.K., Reddy, S., Jayaraman, V., Krishna, K., Song, Q., Rajasekaran, K.E., Wang, T.H., Bei, K. and Rajasekaran, J.J. (2023) Relationship of High Sensitivity C-Reactive Protein with Cardiovascular, Diabetic, and Hepatic Biomarkers. International Journal of Clinical Medicine, 14, 389-401. https://doi.org/10.4236/ijcm.2023.149035