Genetically determined serum levels of mannose-binding lectin correlate negatively with common carotid intima-media thickness in systemic lupus erythematosus

The role of mannose-binding lectin (MBL) in diabetic retinopathy: A scoping review

Diabetes mellitus (DM) is a chronic systemic disease characterized by a multifactorial nature, which may lead to several macro and microvascular complications. Diabetic retinopathy (DR) is one of the most severe microvascular complications of DM, which can result in permanent blindness. The mechanisms involved in the pathogenesis of DR are multiple and still poorly understood. Factors such as dysregulation of vascular regeneration, oxidative and hyperosmolar stress in addition to inflammatory processes have been associated with the pathogenesis of DR. Furthermore, compelling evidence shows that components of the immune system, including the complement system, play a relevant role in the development of the disease. Studies suggest that high concentrations of mannose-binding lectin (MBL), an essential component of the complement lectin pathway, may contribute to the development of DR in patients with DM. This review provides an update on the possible role of the complement system, specifically the lectin pathway, in the pathogenesis of DR and discusses the potential of MBL as a non-invasive biomarker for both, the presence and severity of DR, in addition to its potential as a therapeutic target for intervention strategies.

Endothelial function and endothelial progenitor cells in systemic lupus erythematosus

The observations that traditional cardiovascular disease (CVD) risk factors fail to fully account for the excessive cardiovascular mortality in patients with systemic lupus erythematosus (SLE) compared with the general population have prompted in-depth investigations of non-traditional, SLE-related risk factors that contribute to cardiovascular complications in patients with SLE. Of the various perturbations of vascular physiology, endothelial dysfunction, which is believed to occur in the earliest step of atherosclerosis, has been extensively investigated for its contribution to CVD risk in SLE. Endothelial progenitor cells (EPCs), which play a crucial part in vascular repair, neovascularization and maintenance of endothelial function, are quantitatively and functionally reduced in patients with SLE. Yet, the lack of a unified definition of EPCs, standardization of the quantity and functional assessment of EPCs as well as endothelial function measurement pose challenges to the translation of endothelial function measurements and EPC levels into prognostic markers for CVD in patients with SLE. This Review discusses factors that contribute to CVD in SLE, with particular focus on how endothelial function and EPCs are evaluated currently, and how EPCs are quantitatively and functionally altered in patients with SLE. Potential strategies for the use of endothelial function measurements and EPC quantification as prognostic markers of CVD in patients with SLE, and the limitations of their prognostication potential, are also discussed.

A systemic review into carotid plaque features as predictors of restenosis after carotid endarterectomy

OBJECTIVE

Restenosis after carotid endarterectomy (CEA) limits its long-term efficacy for stroke prevention. Thus, it is of utmost importance to identify the factors that predispose a patient to restenosis after CEA. This systemic review aims to survey the current literature regarding restenosis after CEA and discuss the predictive value of carotid plaque features.

METHODS

A systemic review of studies on the predictive value of carotid plaque features for restenosis after CEA was conducted according to the PRISMA guidelines. PubMed/MEDLINE and Embase databases were searched up to March 20, 2020. Two authors independently extracted the data and assessed the risk of bias with the Quality in Prognosis Studies tool. Given the heterogeneity in the measurement of prognostic factors, types of CEA, and clinical outcomes, a qualitative synthesis was performed.

RESULTS

Twenty-one articles with a sample size that ranged from 11 to 1203 were included in this systematic review. Based on the presence of calcification in original carotid plaques, two progression patterns of restenosis were hypothesized: patients with calcified plaques may experience a temporary increase in the intima-media thickness (IMT) followed by a decrease in IMT after CEA, whereas patients with noncalcified plaques may experience a gradual increase in IMT after CEA. Accordingly, patients with a high calcium score may have a high restenosis rate within 6 months after CEA and a low restenosis rate thereafter. Thus, the late restenosis rate in patients with uniformly echogenic plaques was lower than that in patients with uniformly echolucent plaques. Pathologically, a lipid-rich, inflammatory carotid plaque is associated with a decreased risk of restenosis within 1 year after CEA, mainly owing to the relatively mild reactive intimal hyperplasia at the surgical site and active inflammation in the remaining media and adventitia. Molecular predictors for restenosis included a Mannose-binding lectin 2 genotype, preoperative C-reactive protein, serum homocysteine, apolipoprotein J, vitamin C, and telomere length of carotid plaques.

CONCLUSIONS

This review demonstrated that carotid plaque features, including imaging features, cellular composition, and molecular features, are correlated with the risk of restenosis after CEA. A comprehensive evaluation of plaque characteristics may help to stratify the risk of restenosis after CEA.

Plasma ficolin levels and risk of nephritis in Danish patients with systemic lupus erythematosus

Given the scavenging properties of ficolins, we hypothesized that variation in the plasma concentrations of the three ficolins may be associated with development of lupus nephritis (LN), type of LN, end-stage renal disease (ESRD), and/or mortality among patients with systemic lupus erythematosus (SLE). SLE patients attending a Danish tertiary rheumatology referral center were included. Plasma concentrations of ficolin-1, ficolin-2, and ficolin-3 were determined and dichotomized by the median into high and low. LN was defined by clinical criteria; type of LN by renal biopsy; ESRD follow-up time was defined as time from onset of LN to the development of ESRD or censoring at the end of follow-up. The study included 112 SLE patients with median disease duration of 8 years of which 53 (47%) had LN at the time of inclusion. During a median follow-up of 10 years, five patients developed ESRD. Sixteen patients died. Odds ratios (ORs) of LN were 1.2 (95% CI: 0.6-2.7), 4.1 (95% CI: 1.7-9.7), and 0.9 (95% CI: 0.4-2.0) for patients with low ficolin-1, ficolin-2, and ficolin-3 plasma levels, respectively. The distribution of histological classes differed between patients with high and low plasma levels of ficolin-1 (p = 0.009). Patients with high ficolin-1 plasma levels had an increased risk of ESRD. There was no association between the levels of the analyzed plasma ficolins and mortality. Low plasma ficolin-2 levels were associated with an increased risk of having LN. High plasma levels of ficolin-1 were associated with the histological subtype of LN and development of ESRD.

Mannose-Binding Lectin Levels and Carotid Intima-Media Thickness in Type 2 Diabetic Patients

INTRODUCTION

Mannose-binding lectin (MBL) activates complement system and has been suggested to play a role in vascular complications in diabetics. Carotid intima-media thickness (cIMT) detects subclinical atherosclerosis. We evaluated the association of MBL and IMT in type 2 diabetic (T2DM) patients.

METHODS

Serum MBL levels and cIMT were measured in a total of 103 diabetics and in 98 age-matched healthy controls.

RESULTS

There was no significant difference in MBL level in T2DM versus controls. As expected, IMT was significantly higher in T2DM patients than in controls (P = 0.001). In T2DM, the lowest cIMT was seen in patients with normal MBL level (500-1000) while cIMT continuously increased with both high MBL and absolute MBL deficiency states. This was especially significant in high MBL versus normal MBL T2DM patients (P = 0.002). According to multiple regression analysis the main predictors of IMT in T2DM are age (P < 0.003), ApoA level (P = 0.023), and the MBL (P = 0.036).

CONCLUSIONS

Our results suggest a dual role of MBL as a risk factor for cIMT in T2DM. MBL may also be used as a marker of macrovascular disease, as both low and high levels indicate the susceptibility for atherosclerosis in T2DM.

Cardiovascular involvement in autoimmune diseases

Autoimmune diseases (AD) represent a broad spectrum of chronic conditions that may afflict specific target organs or multiple systems with a significant burden on quality of life. These conditions have common mechanisms including genetic and epigenetics factors, gender disparity, environmental triggers, pathophysiological abnormalities, and certain subphenotypes. Atherosclerosis (AT) was once considered to be a degenerative disease that was an inevitable consequence of aging. However, research in the last three decades has shown that AT is not degenerative or inevitable. It is an autoimmune-inflammatory disease associated with infectious and inflammatory factors characterized by lipoprotein metabolism alteration that leads to immune system activation with the consequent proliferation of smooth muscle cells, narrowing arteries, and atheroma formation. Both humoral and cellular immune mechanisms have been proposed to participate in the onset and progression of AT. Several risk factors, known as classic risk factors, have been described. Interestingly, the excessive cardiovascular events observed in patients with ADs are not fully explained by these factors. Several novel risk factors contribute to the development of premature vascular damage. In this review, we discuss our current understanding of how traditional and nontraditional risk factors contribute to pathogenesis of CVD in AD.

If there is an evolutionary selection pressure for the high frequency of MBL2 polymorphisms, what is it?

Either immune selection or stochastic processes may have influenced the frequency of highly polymorphic genes such as mannose-binding lectin 2 (MBL2). This pattern recognition receptor of the innate immune system recognizes and binds to pathogenic microorganisms and apoptotic cells leading to lectin pathway complement killing or clearance. In almost all of a large number of studies in different ethnic groups worldwide there is 20-25% carriage of low MBL2 haplotypes, with 8-10% of each population having no MBL detectable in the blood. The source of this high variability of MBL2 remains cryptic. It arises from six main snps in the prompter and exon regions of the gene that assort into seven common haplotypes under linkage disequilibrium. While global studies of MBL2 show that it is not under immune selection pressure, these results are not the same when the same population genetic tools are used on large national studies. Other analyses point to the silenced MBL1 pseudogene and development of promoter polymorphisms in humans as evidence of selection pressure favouring low-producing haplotypes. While these analyses cannot be reconciled readily, there are two processes by which MBL heterozygosity could have been advantageous in an evolutionary sense; protection against adverse effects of various infectious diseases and lethal manifestations of atherosclerosis - a disease that now seems to have a more ancient history than assumed previously. Ultimately, consideration of the context for possible future therapeutic manipulation of MBL means that this can proceed independently of resolution of the evolutionary forces that have shaped MBL2 polymorphism.

MBL2 gene variants coding for mannose-binding lectin deficiency are associated with increased risk of nephritis in Danish patients with systemic lupus erythematosus

OBJECTIVES

Autoimmunity may in part result from deficiencies in the processing of apoptotic debris. As mannose-binding lectin (MBL) is involved in such processes, we hypothesized that the variants in the MBL2 gene resulting in MBL deficiency confer an increased risk of nephritis in systemic lupus erythematosus (SLE).

METHODS

A total of 171 SLE patients attending a Danish tertiary rheumatology referral center were included. Common variant alleles in exon 1 of the MBL2 gene (R52C, rs5030737; G54D, rs1800450; G57E, rs1800451) were genotyped. The normal allele and variant alleles are termed A and O, respectively. The follow-up period was defined as the time from fulfillment of the ACR 1987 classification criteria for SLE until the occurrence of an event (nephritis, end-stage renal disease (ESRD), or death) or end of follow-up. Cox regression analyses were controlled for gender, age and race.

RESULTS

During a median follow-up of 5.7 years, nephritis developed in 94 patients, and ESRD developed in 16 of these patients. Twenty-seven patients died. The distribution of the MBL2 genotypes A/A, A/O and O/O was 58%, 35% and 7.0%, respectively. Compared to the rest, O/O patients had 2.6 times (95% CI: 1.2-5.5) higher risk of developing nephritis, and their risk of death after 10 years was 6.0 times increased (95% CI: 1.0-36). MBL serum levels below 100 ng/ml were associated with a 2.0 (95% CI: 1.2-3.4; p = 0.007) increased risk of developing nephritis. ESRD and histological class of nephritis were not associated with MBL deficiency.

CONCLUSIONS

Genetically determined MBL deficiency was associated with development of nephritis in SLE patients, but not with histological class of nephritis or ESRD.

Genetic variation and coronary atherosclerosis in patients with systemic lupus erythematosus

Coronary artery disease is the major cause of mortality in patients with systemic lupus erythematosus (SLE). Increased cardiovascular risk in SLE is not explained by traditional risk factors. We examined the hypothesis that genetic variation contributes to the presence of coronary atherosclerosis in patients with SLE. The genotypes of single-nucleotide polymorphisms (SNP) in 152 candidate genes linked with autoimmune or cardiovascular risk were determined in 125 patients with SLE. Coronary artery calcium (CAC), a measure of coronary atherosclerosis, was detected in 32 patients (26%) by electron-beam computed tomography. Polymorphism in 20 of the candidate genes (ADAM33, ADIPOQ, CCL5, CCR7, CDKN2B, CSF1, IL4, IL12A, IL23R, INS, IRF5, MIF, MS4A1, PTGS1, PTPN22, RETN, SELE, TNFSF4, TNFRSF11B, and VCAM1) were nominally associated with the presence of CAC (p-values = 0.001-0.047 after adjustment for age, sex and race). Some of these are known susceptibility genes for SLE and others have been implicated in cardiovascular disease in other populations. No association withstood false discovery rate adjustment. Replication studies in additional cohorts of patients with SLE may be informative.

Imbalance between endothelial damage and repair: a gateway to cardiovascular disease in systemic lupus erythematosus

Atherosclerosis is accelerated in patients with systemic lupus erythematosus (SLE) and it leads to excessive cardiovascular complications in these patients. Despite the improved awareness of cardiovascular disease and advent of clinical diagnostics, the process of atherogenesis in most patients remains clinically silent until symptoms and signs of cardiovascular complications develop. As evidence has demonstrated that vascular damage is already occurring before clinically overt cardiovascular disease develops in lupus patients, intervention at the preclinical stage of atherogenesis would be plausible. Indeed, endothelial dysfunction, one of the earliest steps of atherogenesis, has been demonstrated to occur in lupus patients even when they are naïve for cardiovascular disease. Currently known “endothelium-toxic” factors including type 1 interferon, proinflammatory cytokines, inflammatory cells, immune complexes, costimulatory molecules, neutrophils extracellular traps, lupus-related autoantibodies, oxidative stress, and dyslipidemia, coupled with the aberrant functions of the endothelial progenitor cells (EPC) which are crucial to vascular repair, likely tip the balance towards endothelial dysfunction and propensity to develop cardiovascular disease in lupus patients. In this review, altered physiology of the endothelium, factors leading to perturbed vascular repair contributed by lupus EPC and the impact of proatherogenic factors on the endothelium which potentially lead to atherosclerosis in lupus patients will be discussed.

Definitions of and contributions to cardiovascular disease in systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) have a significantly increased risk of cardiovascular disease (CVD). Increased prevalence of atherosclerosis may explain part of this enhanced risk, but SLE related CVD can also result from other mechanisms. Vascular events may be the result of several pathophysiologic mechanisms; some can be caused by atherosclerosis, others may be primarily thrombotic, and some may be due to ongoing inflammation. The traditional risk factors are of importance for the development of CVD in lupus. However, lupus-related factors, such as endothelial dysfunction and inflammation, renal impairment and disease activity, lupus phenotype, autoantibodies and genetic predisposition are equally or even more important. Risk factors may also contribute separately or in combination to increase the risk of atherosclerosis and clinical CVD in SLE. Studies investigating risk factors for CVD in SLE vary with respect to definition of outcome, it is, e.g. common that the terms atherosclerosis and clinical CVD are used interchangeably. Varying definitions and outcomes may thus explain divergent results of different studies and make comparisons difficult. This review summarizes some of the current knowledge regarding risk factors and mechanisms for atherosclerosis and clinical CVD in SLE. Aspects on the importance of CVD definitions and outcomes are briefly discussed.

Cardiovascular disease in latin american patients with systemic lupus erythematosus: a cross-sectional study and a systematic review

Objective. This study was performed to determine the prevalence of and associated risk factors for cardiovascular disease (CVD) in Latin American (LA) patients with systemic lupus erythematosus (SLE). Methods. First, a cross-sectional analytical study was conducted in 310 Colombian patients with SLE in whom CVD was assessed. Associated factors were examined by multivariate regression analyses. Second, a systematic review of the literature on CVD in SLE in LA was performed. Results. There were 133 (36.5%) Colombian SLE patients with CVD. Dyslipidemia, smoking, coffee consumption, and pleural effusion were positively associated with CVD. An independent effect of coffee consumption and cigarette on CVD was found regardless of gender and duration of disease. In the systematic review, 60 articles fulfilling the eligibility criteria were included. A wide range of CVD prevalence was found (4%-79.5%). Several studies reported ancestry, genetic factors, and polyautoimmunity as novel risk factors for such a condition. Conclusions. A high rate of CVD is observed in LA patients with SLE. Awareness of the observed risk factors should encourage preventive population strategies for CVD in patients with SLE aimed at facilitating the suppression of cigarette smoking and coffee consumption as well as at the tight control of dyslipidemia and other modifiable risk factors.

Mannose-binding lectin deficiency is associated with myocardial infarction: the HUNT2 study in Norway

OBJECTIVES

Mannose-binding lectin (MBL) and ficolins activate the complement cascade, which is involved in atherogenesis. Based on a pilot study, we hypothesized that functional polymorphisms in the MBL gene (MBL2) leading to dysfunctional protein are related to development of myocardial infarction (MI). The aim of the present study was to study polymorphisms in MBL2 and ficolin genes in relation to the risk of MI.

METHODS AND RESULTS

Using the population-based HUNT Study in Norway, 57,133 persons were followed up for a first-time MI from 1995-1997 until the end of 2008. The 370 youngest MI patients were matched by age (range 29-62 years) and gender to 370 controls. A younger population was selected because disease in this group might be less dependent on non-genetic risk factors. The study size was based on power calculation. Polymorphisms in MBL2 and in the genes of ficolin-1, ficolin-2 and ficolin-3 were genotyped by pyrosequencing and related to the risk of MI, estimated as odds ratios (OR). Functional haplotypes were analyzed and stringent alpha levels of significance were set by permutation testing. Variant MBL2 haplotypes causing MBL deficiency were associated with a two-fold higher risk of MI (OR 2.04, 95%CI 1.29-3.24). Adjustments for conventional cardiovascular risk factors did not substantially influence the association. The ficolins were not associated with MI risk.

CONCLUSION

In a young to middle aged and relatively healthy Caucasian population, MBL2 variants related to functional MBL deficiency were associated with a doubling of the risk for MI, independent of conventional risk factors. This supports that MBL deficiency may lead to increased atherosclerosis or development of vulnerable plaques.

Ethnic differences in cardiovascular risk in rheumatic disease: focus on Asians

Rheumatic diseases are associated with high cardiovascular morbidity and mortality. Considerable differences exist in the frequency of cardiovascular disease (CVD) risk factors and events among people of different ethnic origins, but little is known of the ethnic variations in the relative distribution of CVD risk factors and the degree of atherosclerosis in patients with rheumatic diseases. Understanding this variation will provide insight into the underlying pathogenesis of CVD in patients with rheumatic diseases, and aid in future studies of the detection and management of this complication. In general, although Asian patients seem to have fewer background CVD risk factors and are less affected by metabolic syndrome (MetS) than their non-Asian counterparts, those with rheumatic disease are equally as susceptible to CVD. Furthermore, it seems that systemic inflammation and mechanisms that do not involve conventional CVD risk factors and MetS have an important role in the development of atherosclerosis in patients with rheumatic diseases. Here we examine the frequency of conventional CVD risk factors and the prevalence of MetS in both Asian and non-Asian patients with selected rheumatic diseases. We also discuss the burden of CVD, as evaluated using various surrogate markers in these patients, and their overall CVD mortality rate.