Cholesteryl ester transfer protein in patients with rheumatoid arthritis

Dyslipidemia in rheumatoid arthritis: the possible mechanisms

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease, of which the leading cause of death is cardiovascular disease (CVD). The levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) in RA decrease especially under hyperinflammatory conditions. It is conflictive with the increased risk of CVD in RA, which is called "lipid paradox". The systemic inflammation may explain this apparent contradiction. The increased systemic proinflammatory cytokines in RA mainly include interleukin-6(IL-6)、interleukin-1(IL-1)and tumor necrosis factor alpha(TNF-α). The inflammation of RA cause changes in the subcomponents and structure of HDL particles, leading to a weakened anti-atherosclerosis function and promoting LDL oxidation and plaque formation. Dysfunctional HDL can further worsen the abnormalities of LDL metabolism, increasing the risk of cardiovascular disease. However, the specific mechanisms underlying lipid changes in RA and increased CVD risk remain unclear. Therefore, this article comprehensively integrates the latest existing literature to describe the unique lipid profile of RA, explore the mechanisms of lipid changes, and investigate the impact of lipid changes on cardiovascular disease.

The Sizes and Composition of HDL-Cholesterol Are Significantly Associated with Inflammation in Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA), a chronic inflammatory disease, carries a significant burden of atherosclerotic cardiovascular diseases (ASCVD). With their heterogeneous composition, high-density lipoprotein (HDL) particles have varied athero-protective properties, and some may even increase ASCVD risk. In this prospective and cross-sectional study, we aimed to examine the relationship between HDL sizes/metabolites and inflammation in RA. Using ¹H-NMR-based lipid/metabolomics, differential HDL-related metabolites were identified between RA patients and healthy control (HC) subjects and between RA patients with and without anti-citrullinated peptide antibodies (ACPA). The correlation between the discriminative HDL-related metabolites and C-reactive protein (CRP) was evaluated in RA patients. RA patients demonstrated higher particle number, lipids, cholesterol, cholesterol ester, free cholesterol, and phospholipids in large/very large-sized HDLs. ACPA-positive patients had higher L-HDL-C and L-HDL-CE but lower small-/medium-sized HDL-TG levels than ACPA-negative patients. An inverse correlation was found between CRP levels and small-sized HDLs. Janus kinase inhibitor treatment was associated with increased serum small-sized HDL-related metabolites and decreased CRP levels. We are the first to reveal the significant associations between RA inflammation and HDL sizes/metabolites. A potential link between ACPA positivity and changes in serum levels of HDL-related metabolites was also observed in RA patients.

Disease-modifying anti-rheumatic drugs improve the cardiovascular profile in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting about 0. 5–1% of the adult population and manifesting as persistent synovitis, systemic inflammation and production of autoantibodies. Patients affected by RA not only experience chronic disease progression, but are also burdened by a 1.5-fold increased cardiovascular (CV) risk, which is comparable to the risk experienced by patients with type 2 diabetes mellitus. RA patients also have a higher incidence and prevalence of coronary artery disease (CAD). Although RA patients frequently present traditional CV risk factors such as insulin resistance and active smoking, previous studies have clarified the pivotal role of chronic inflammation–driven by proinflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha)–in accelerating the process of atherosclerosis and impairing the coagulation system. Over the last years, a number of studies have shown that disease-modifying anti-rheumatic drugs (DMARDs) reducing the inflammatory state in general improve the CV risk, however some drugs may carry some apparent negative effects. Thus, RA is a model of disease in which targeting inflammation may counteract the progression of atherosclerosis and reduce CV risk. Clinical and experimental evidence indicates that the management of RA patients should be tailored based on the positive and negative effects of DMARDs on CV risk together with the individual traditional CV risk profile. The identification of genetic, biochemical and clinical biomarkers, predictive of evolution and response to treatment, will be the next challenge for a precision approach to reduce the burden of the disease.

New insights into the emerging effects of inflammatory response on HDL particles structure and function

According to the increasing results, it has been well-demonstrated that the chronic inflammatory response, including systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease are associated with an increased risk of atherosclerotic cardiovascular disease. The mechanism whereby inflammatory response up-regulates the risk of cardio-metabolic disorder disease is multifactorial; furthermore, the alterations in high density lipoprotein (HDL) structure and function which occur under the inflammatory response could play an important modulatory function. On the other hand, the serum concentrations of HDL cholesterol (HDL-C) have been shown to be reduced significantly under inflammatory status with remarked alterations in HDL particles. Nevertheless, the potential mechanism whereby the inflammatory response reduces serum HDL-C levels is not simply defined but reduces apolipoprotein A1 production. The alterations in HDL structure mediated by the inflammatory response has been also confirmed to decrease the ability of HDL particle to play an important role in reverse cholesterol transport and protect the LDL particles from oxidation. Recently, it has been shown that under the inflammatory condition, diverse alterations in HDL structure could be observed which lead to changes in HDL function. In the current review, the emerging effects of inflammatory response on HDL particles structure and function are well-summarized to elucidate the potential mechanism whereby different inflammatory status modulates the pathogenic development of dyslipidemia.

Disruptive Selection of Human Immunostimulatory and Immunosuppressive Genes Both Provokes and Prevents Rheumatoid Arthritis, Respectively, as a Self-Domestication Syndrome

Using our previously published Web service SNP_TATA_Comparator, we conducted a genome-wide study of single-nucleotide polymorphisms (SNPs) within core promoters of 68 human rheumatoid arthritis (RA)-related genes. Using 603 SNPs within 25 genes clinically associated with RA-comorbid disorders, we predicted 84 and 70 candidate SNP markers for overexpression and underexpression of these genes, respectively, among which 58 and 96 candidate SNP markers, respectively, can relieve and worsen RA as if there is a neutral drift toward susceptibility to RA. Similarly, we predicted natural selection toward susceptibility to RA for 8 immunostimulatory genes (e.g., IL9R) and 10 genes most often associated with RA (e.g., NPY). On the contrary, using 25 immunosuppressive genes, we predicted 70 and 109 candidate SNP markers aggravating and relieving RA, respectively (e.g., IL1R2 and TGFB2), suggesting that natural selection can simultaneously additionally yield resistance to RA. We concluded that disruptive natural selection of human immunostimulatory and immunosuppressive genes is concurrently elevating and reducing the risk of RA, respectively. So, we hypothesize that RA in human could be a self-domestication syndrome referring to evolution patterns in domestic animals. We tested this hypothesis by means of public RNA-Seq data on 1740 differentially expressed genes (DEGs) of pets vs. wild animals (e.g., dogs vs. wolves). The number of DEGs in the domestic animals corresponding to worsened RA condition in humans was significantly larger than that in the related wild animals (10 vs. 3). Moreover, much less DEGs in the domestic animals were accordant to relieved RA condition in humans than those in the wild animals (1 vs. 8 genes). This indicates that the anthropogenic environment, in contrast to a natural one, affects gene expression across the whole genome (e.g., immunostimulatory and immunosuppressive genes) in a manner that likely contributes to RA. The difference in gene numbers is statistically significant as confirmed by binomial distribution (p < 0.01), Pearson's χ² (p < 0.01), and Fisher's exact test (p < 0.05). This allows us to propose RA as a candidate symptom within a self-domestication syndrome. Such syndrome might be considered as a human's payment with health for the benefits received during evolution.

Lipid Metabolism Profiles in Rheumatic Diseases

Rheumatic diseases are a group of chronic autoimmune disorders that involve multiple organs or systems and have high mortality. The mechanisms of these diseases are still ill-defined, and targeted therapeutic strategies are still challenging for physicians. Recent research indicates that cell metabolism plays important roles in the pathogenesis of rheumatic diseases. In this review, we mainly focus on lipid metabolism profiles (dyslipidaemia, fatty acid metabolism) and mechanisms in rheumatic diseases and discuss potential clinical applications based on lipid metabolism profiles.

HDL cholesterol efflux capacity and lipid profile in patients with systemic sclerosis

OBJECTIVE

It is well established that patients with systemic sclerosis (SSc) have a disrupted lipid profile and an increased cardiovascular risk. Cholesterol efflux capacity (CEC), the ability of high-density lipoprotein (HDL)-cholesterol to accept cholesterol from macrophages, has been linked to cardiovascular events. The aim of this study was to establish whether CEC and lipid profile were impaired in SSc patients with respect to controls and whether these changes were associated with disease-related data.

METHODS

Cross-sectional study encompassed 188 individuals: 73 SSc patients and 115 controls. CEC, using an in vitro assay, and lipoprotein serum concentrations were assessed in patients and controls. A multivariable analysis was performed to study the differences in CEC between patients and controls, and if SSc-related data could explain such differences.

RESULTS

The multivariable analysis adjusted for demographic characteristics, cardiovascular risk factors, and lipid-related molecules showed that total cholesterol (beta coefficient: - 22 [95%CI - 37 to - 7], p = 0.004), triglycerides (beta coefficient: 24 [95%CI 2-47], p = 0.033), lipoprotein A (beta coefficient: 22 [95%CI 2-43], p = 0.033), and CEC (beta coefficient: - 6 [95%CI - 10 to - 2]%,p = 0.002) were significantly different between patients and controls. Skin thickness, as assessed by modified Rodnan skin score, was independently associated with a lower CEC (beta coefficient: - 0.21 [95%CI - 0.37 to - 0.05]%, p = 0.011) after multivariable adjustment.

CONCLUSION

SSc patients show an abnormal lipid profile with respect to controls including CEC. Skin thickness is independent and inversely associated with CEC in SSc patients.

High-Density Lipoprotein Modifications: A Pathological Consequence or Cause of Disease Progression?

High-density lipoprotein (HDL) is well-known for its cardioprotective effects, as it possesses anti-inflammatory, anti-oxidative, anti-thrombotic, and cytoprotective properties. Traditionally, studies and therapeutic approaches have focused on raising HDL cholesterol levels. Recently, it became evident that, not HDL cholesterol, but HDL composition and functionality, is probably a more fruitful target. In disorders, such as chronic kidney disease or cardiovascular diseases, it has been observed that HDL is modified and becomes dysfunctional. There are different modification that can occur, such as serum amyloid, an enrichment and oxidation, carbamylation, and glycation of key proteins. Additionally, the composition of HDL can be affected by changes to enzymes such as cholesterol ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT), and phospholipid transfer protein (PLTP) or by modification to other important components. This review will highlight some main modifications to HDL and discuss whether these modifications are purely a consequential result of pathology or are actually involved in the pathology itself and have a causal role. Therefore, HDL composition may present a molecular target for the amelioration of certain diseases, but more information is needed to determine to what extent HDL modifications play a causal role in disease development.

Untying the correlation between apolipoproteins and rheumatoid arthritis

AIM AND OBJECTIVE

The concentration of lipoproteins and apolipoprotein are extremely low in the synovial fluid of any healthy person as compared to the concentrations in plasma. However, in the synovial fluid of any diseased patient the amount of cholesterol and lipids is sharply increased. The current review defines the role of various apolipoproteins and lipoproteins and their constituent subfractions in the synovial fluid embarking its principal role in rheumatoid arthritis. It also explains the need to define synovial fluid lipids, lipoprotein particle subfractions and their constituent apolipoproteins in synovial fluid.

MATERIALS AND METHODS

Various research and review articles highlighting the role of apolipoproteins and lipoproteins were procured from medical websites mainly Pubmed, Medline, Science Direct, etc., and studied for the writing of the review paper.

CONCLUSION

Mainly apolipoproteins A-1, B and E are prominently increased in chronic inflammatory joint disorders. Several theories have been proposed to understand the source of increase of lipids and apolipoproteins in synovial fluid of the diseased patients compared to healthy individuals, yet the precise mechanism is still not lucid. Lipoproteins are believed to play both functional role and pathological role in the synovial fluid. The activated T-lymphocytes in patients of RA lead to activation of inflammatory cytokines such as tumor necrosis factor and interleukins which embark to be the principal mechanism for induction of the disease. It can be thus concluded that the apolipoproteins prevent the activation of monocytes by blocking their contact of activation and thus play critical role in management of RA by inhibiting the production of proinflammatory cytokines.

Increased cardiovascular risk in rheumatoid arthritis: mechanisms and implications

Rheumatoid arthritis is a systemic autoimmune disease characterized by excess morbidity and mortality from cardiovascular disease. Mechanisms linking rheumatoid arthritis and cardiovascular disease include shared inflammatory mediators, post-translational modifications of peptides/proteins and subsequent immune responses, alterations in the composition and function of lipoproteins, increased oxidative stress, and endothelial dysfunction. Despite a growing understanding of these mechanisms and their complex interplay with conventional cardiovascular risk factors, optimal approaches of risk stratification, prevention, and treatment in the context of rheumatoid arthritis remain unknown. A multifaceted approach to reduce the burden posed by cardiovascular disease requires optimal management of traditional risk factors in addition to those intrinsic to rheumatoid arthritis such as increased disease activity. Treatments for rheumatoid arthritis seem to exert differential effects on cardiovascular risk as well as the mechanisms linking these conditions. More research is needed to establish whether preferential rheumatoid arthritis therapies exist in terms of prevention of cardiovascular disease. Ultimately, understanding the unique mechanisms for cardiovascular disease in rheumatoid arthritis will aid in risk stratification and the identification of novel targets for meaningful reduction of cardiovascular risk in this patient population.

Downregulation of cholesteryl ester transfer protein by glucocorticoids: a randomised study on HDL

BACKGROUND

High density lipoprotein (HDL) cholesterol is not decreased in hypercortisolism despite high triglycerides, which may be ascribed to effects on the cholesteryl ester transfer protein (CETP) pathway. We explored if CETP mRNA expression is modulated by glucocorticoid treatment in vitro. Effects of doubling the hydrocortisone (HCT) replacement dose on plasma CETP activity, and HDL characteristics were tested in patients with secondary adrenal insufficiency.

MATERIALS AND METHODS

Human THP-1 macrophages were incubated with corticosterone in vitro in the presence or absence of a liver X receptor (LXR) agonist, followed by determination of CETP mRNA levels by quantitative real-time PCR. In addition, a randomised double-blind cross-over study was performed in 47 patients with secondary adrenal insufficiency (university medical setting; 10 weeks exposure to a higher HCT dose (0·4-0·6 mg/kg body weight) vs. 10 weeks of a lower HCT dose (0·2-0·3 mg/kg body weight).

RESULTS

Corticosterone dose dependently decreased CETP mRNA in THP-1 macrophages. Corticosterone also decreased CETP mRNA expression after LXR pretreatment. In patients, CETP activity decreased with doubling of the HCT dose (P = 0·049), coinciding with an increase in HDL cholesterol, apolipoprotein A-I and the HDL cholesterol/apolipoprotein A-I ratio (reflecting HDL size; P < 0·01 for each). The increase in the HDL cholesterol/apolipoprotein A-I ratio was correlated with the decrease in plasma CETP activity (r = -0·442, P = 0·002).

CONCLUSION

Glucocorticoids downregulate CETP gene expression in a human macrophage cell system. In line, a higher glucocorticoid replacement dose decreases plasma CETP activity in patients, thereby contributing to higher HDL cholesterol and an increase in estimated HDL size.

Effect of inflammation on HDL structure and function

PURPOSE OF REVIEW

Studies have shown that chronic inflammatory disorders, such as rheumatoid arthritis, systemic lupus erythematosus, and psoriasis are associated with an increased risk of atherosclerotic cardiovascular disease. The mechanism by which inflammation increases cardiovascular disease is likely multifactorial but changes in HDL structure and function that occur during inflammation could play a role.

RECENT FINDINGS

HDL levels decrease with inflammation and there are marked changes in HDL-associated proteins. Serum amyloid A markedly increases whereas apolipoprotein A-I, lecithin:cholesterol acyltransferase, cholesterol ester transfer protein, paraoxonase 1, and apolipoprotein M decrease. The exact mechanism by which inflammation decreases HDL levels is not defined but decreases in apolipoprotein A-I production, increases in serum amyloid A, increases in endothelial lipase and secretory phospholipase A2 activity, and decreases in lecithin:cholesterol acyltransferase activity could all contribute. The changes in HDL induced by inflammation reduce the ability of HDL to participate in reverse cholesterol transport and protect LDL from oxidation.

SUMMARY

During inflammation multiple changes in HDL structure occur leading to alterations in HDL function. In the short term, these changes may be beneficial resulting in an increase in cholesterol in peripheral cells to improve host defense and repair but over the long term these changes may increase the risk of atherosclerosis.

Risk factors for cardiovascular disease in rheumatoid arthritis patients from Mato Grosso do Sul

OBJECTIVE

To identify risk factors for cardiovascular disease in patients with Rheumatoid Arthritis (RA).

MATERIAL AND METHODS

A descriptive cross-sectional study with 71 patients with established RA. The instruments used were: DAS-28, HAQ and SF-36, and the following parameters were determined: the erythrocyte sedimentation rate, capillary blood glucose; total cholesterol (TC) and its fractions, thyroid hormones, antinuclear antibodies (ANA), rheumatoid factor (RF) and antibodies against citrullinated proteins (ACPAs). Patients were classified into groups HAQ ≤ 1 (mild dysfunction) and HAQ > 1 (moderate and severe dysfunction) and, according to the HAQ scores, in groups treated with corticosteroids (CS) and without CS.

RESULTS

9 patients were male and 62 female with mean age and duration of disease of 53.45 (± 10.7) and 9.9 (± 8.6), respectively. RF was positive in 52 (76%), ACPAs in 54 (76.1%) and ANA in 12 (16.9%). Thirty-six patients (50.7%) had systemic hypertension, 9 (12.68%) diabetes mellitus, 16 (22.5%) hypothyroidism, 33 (46.5%) dyslipidemia and 8 (11.27%) were smokers. The results of TC >240 were found in 53.8% for group HAQ >1 (26) and in 24.4% for group HAQ ≤ 1 (45) (p=0.020). These groups did not differ as to presence of comorbidities or drug treatment. Triglyceride levels >200 for the group with CS (42.4%) versus without CS (18.42%) were significant (p=0.025).

CONCLUSION

An association of increased TC and triglycerides with results of HAQ ≤ 1 and with CS use was noted, reinforcing the importance of screening risk factors associated with cardiovascular disease in RA.

Inflammation, lipid metabolism and cardiovascular risk in rheumatoid arthritis: A qualitative relationship?

Life expectancy in patients with rheumatoid arthritis (RA) is reduced compared to the general population owing to an increase in cardiovascular diseases (CVD) not fully explained by traditional cardiovascular risk factors. In recent years, interest has been focused on the alterations in lipid metabolism in relation to chronic inflammation as one of the possible mechanisms involved in the pathogenesis of atherosclerosis of RA patients. Research regarding this issue has revealed quantitative alterations in lipoproteins during the acute-phase reaction, and has also demonstrated structural alterations in these lipoproteins which affect their functional abilities. Although many alterations in lipid metabolism have been described in this regard, these structural changes associated with inflammation are particularly important in high-density lipoproteins as they affect their cardioprotective functions. In this respect, excessive oxidation in low-density lipoprotein (LDL) and increased lipoprotein(a) with a predominance of smaller apolipoprotein(a) isoforms has also been reported. This article will discuss proinflammatory high-density lipoproteins (piHDL), oxidized LDL and lipoprotein(a). Elevated concentrations of these lipoproteins with marked pro-atherogenic properties have been observed in RA patients, which could help to explain the increased cardiovascular risk of these patients.