Understanding the role of circulating chemokine (C-C motif) ligand 2 in patients with chronic ischemia threatening the lower extremities

Endothelial cell dysfunction: Implications for the pathogenesis of peripheral artery disease

Peripheral artery disease (PAD) is caused by occluded or narrowed arteries that reduce blood flow to the lower limbs. The treatment focuses on lifestyle changes, management of modifiable risk factors and vascular surgery. In this review we focus on how Endothelial Cell (EC) dysfunction contributes to PAD pathophysiology and describe the largely untapped potential of correcting endothelial dysfunction. Moreover, we describe current treatments and clinical trials which improve EC dysfunction and offer insights into where future research efforts could be made. Endothelial dysfunction could represent a target for PAD therapy.

Quantile-specific heritability of monocyte chemoattractant protein-1, and relevance to rs1024611-disease interactions

BACKGROUND

Monocyte chemoattractant protein-1 (MCP-1) concentrations are 34% to 47% heritable. Larger -2518 G/A (rs1024611) genotypes differences are reported for: 1) MCP-1 production in stimulated vs. basal cells; and 2) MCP-1 concentrations in diseased (sepsis, brain abscess, hepatitis B virus, Alzheimer's disease, Behcet's disease, and systemic lupus erythematosus) vs. healthy patients. Those results suggest that the -2518 G/A effect size may depend on whether the phenotype is high or low relative to its distribution (quantile-dependent expressivity).

METHOD

To test whether quantile-dependent expressivity applies more broadly to genetic influences on MCP-1 concentrations, quantile-specific offspring-parent (βOP) and full-sib regression slopes (βFS) were estimated by applying quantile regression to the age- and sex-adjusted serum MCP-1 concentrations of Framingham Heart Study families. Quantile-specific heritabilities were calculated as h2 = 2βOP/(1 + rspouse) and h2={(1 + 8rspouseβFS)0.5-1}/(2rspouse)).

RESULTS

Heritability (h2 ± SE) of MCP-1 concentrations increased from 0.15 ± 0.05 at the 10th percentile of the MCP-1 distribution, 0.23 ± 0.04 at the 25th, 0.32 ± 0.05 at the 50th, 0.43 ± 0.07 at the 75th, and 0.44 ± 0.07 at the 90th percentile, or an 0.0041 ± 0.0009 increase for each one-percent increment in the MCP-1 distribution (Plinear trend = 2.4 × 10-5) when estimated from βOP, and (Plinear trend = 7.7 × 10-9) when estimated from βFS. Compared to the 10th percentile, βOP-estimated h2 was 3-fold greater at the 90th percentile (Pdifference = 0.0003), and 6.9-fold greater when estimated from βFS (Pdifference = 3.3 × 10-6). Re-analysis of in vivo comparison of MCP-1 concentrations in controls vs. patients with MCP-1-elevating conditions, and in vitro studies of MCP-1 production in basal vs. stimulated cells, show rs1024611 genotypes differences that were consistent with quantile-dependent expressivity.

CONCLUSION

The heritability of circulating MCP-1 concentrations is quantile-dependent.

On the Role of Paraoxonase-1 and Chemokine Ligand 2 (C-C motif) in Metabolic Alterations Linked to Inflammation and Disease. A 2021 Update

Infectious and many non-infectious diseases share common molecular mechanisms. Among them, oxidative stress and the subsequent inflammatory reaction are of particular note. Metabolic disorders induced by external agents, be they bacterial or viral pathogens, excessive calorie intake, poor-quality nutrients, or environmental factors produce an imbalance between the production of free radicals and endogenous antioxidant systems; the consequence being the oxidation of lipids, proteins, and nucleic acids. Oxidation and inflammation are closely related, and whether oxidative stress and inflammation represent the causes or consequences of cellular pathology, both produce metabolic alterations that influence the pathogenesis of the disease. In this review, we highlight two key molecules in the regulation of these processes: Paraoxonase-1 (PON1) and chemokine (C-C motif) ligand 2 (CCL2). PON1 is an enzyme bound to high-density lipoproteins. It breaks down lipid peroxides in lipoproteins and cells, participates in the protection conferred by HDL against different infectious agents, and is considered part of the innate immune system. With PON1 deficiency, CCL2 production increases, inducing migration and infiltration of immune cells in target tissues and disturbing normal metabolic function. This disruption involves pathways controlling cellular homeostasis as well as metabolically-driven chronic inflammatory states. Hence, an understanding of these relationships would help improve treatments and, as well, identify new therapeutic targets.

Perivascular Macrophages Regulate Blood Flow Following Tissue Damage

[Figure: see text].

Chemokine (C-C motif) ligand 2 and coronary artery disease: Tissue expression of functional and atypical receptors

Chemokines, particularly chemokine (C-C- motif) ligand 2 (CCL2), control leukocyte migration into the wall of the artery and regulate the traffic of inflammatory cells. CCL2 is bound to functional receptors (CCR2), but also to atypical chemokine receptors (ACKRs), which do not induce cell migration but can modify chemokine gradients. Whether atherosclerosis alters CCL2 function by influencing the expression of these receptors remains unknown. In a necropsy study, we used immunohistochemistry to explore where and to what extent CCL2 and related receptors are present in diseased arteries that caused the death of men with coronary artery disease compared with unaffected arteries. CCL2 was marginally detected in normal arteries but was more frequently found in the intima. The expression of CCL2 and related receptors was significantly increased in diseased arteries with relative differences among the artery layers. The highest relative increases were those of CCL2 and ACKR1. CCL2 expression was associated with a significant predictive value of atherosclerosis. Findings suggest the need for further insight into receptor specificity or activity and the interplay among chemokines. CCL2-associated conventional and atypical receptors are overexpressed in atherosclerotic arteries, and these may suggest new potential therapeutic targets to locally modify the overall anti-inflammatory response.

Impact of DARC rs12075 Variants on Liver Fibrosis Progression in Patients with Chronic Hepatitis C: A Retrospective Study

: The Duffy antigen receptor for chemokines (DARC) rs12075 polymorphism regulates leukocyte trafficking and proinflammatory chemokine homeostasis. Hepatitis C virus (HCV)-mediated liver fibrosis is associated with an uncontrolled inflammatory response. In this study, we evaluate the association between the DARC rs12075 polymorphism and liver stiffness progression in HCV-infected patients. We carried out a retrospective cohort study (repeated measures design) in 208 noncirrhotic patients with chronic hepatitis C (CHC) who had at least two liver stiffness measurements (LSM) with a separation of at least 12 months. We used generalized linear models to analyze the association between DARC rs12075 polymorphism and outcome variables. During a follow-up of 46.6 months, the percentage of patients with stages of fibrosis F0/F1 decreased (p < 0.001), while LSM values and the percentage of patients with cirrhosis increased (p < 0.001). This pattern of changes was maintained in each of the groups of patients analyzed according to their rs12075 genotypes (AA or AG/GG). However, the variations in liver stiffness characteristics were lower in patients with the rs12075 AG/GG genotype (AG/GG versus AA). Thereby, in the adjusted analysis, patients with the rs12075 AG/GG genotype had a lower risk of an increased value of LSM2/LSM1 arithmetic mean ratio (AMR = 0.83; p = 0.001) and of an increase in LSM ≥ 5 kPa (odds ratio (OR) = 0.28; p = 0.009). Besides, patients with rs12075 AG/GG had a lower risk of cirrhosis progression (OR = 0.24; p = 0.009). No significant associations were found for an increase in LSM ≥ 10 kPa. We found an association between the DARC rs12075 single nucleotide polymorphism (SNP) and CHC progression. Specifically, patients with the DARC rs12075 AG/GG genotype had a lower risk of liver fibrosis progression and development of cirrhosis.

Searching for the Genetic Determinants of Peripheral Arterial Disease: A Review of the Literature and Future Directions

Peripheral arterial disease (PAD) is a significant but under-recognized disease that is poorly understood despite population-scale genetic studies. To address this morbid disease, clinicians need additional tools to identify, prevent, and treat patients at risk for PAD. Genetic studies of coronary artery disease have yielded promising results for clinical application, which have thus far been lacking in PAD. In this article, we review recent findings, discuss limitations, and propose future directions of genomic study and clinical application. However, despite many studies, we still lack definitive genetic markers for PAD. This can be attributed to the heterogeneity of PAD's pathogenesis and clinical manifestations, as well as inconsistencies in study methodologies, limitations of current genetic assessment techniques, incompletely comprehended molecular pathophysiology, and confounding generalized atherosclerotic risk factors. The goals of this review are to evaluate the limitations of our current genetic knowledge of PAD and to propose approaches to expedite the identification of valuable markers of PAD.

Assessment of extracellular matrix-related biomarkers in patients with lower extremity artery disease

BACKGROUND

The prevalence of lower extremity artery disease (LEAD) is high (20%-25%) in the population older than 65 years, but patients are seldom identified until the disease is advanced. Circulating markers of disease activity might provide patients with a key opportunity for timely treatment. We tested the hypothesis that measuring blood-specific fragments generated during degradation of the extracellular matrix (ECM) could provide further insight into the pathophysiologic mechanism of arterial remodeling.

METHODS

The protein profile of diseased arteries from patients undergoing infrainguinal limb revascularization was assessed by a liquid chromatography and tandem mass spectrometry, nontargeted proteomic approach. The information retrieved was the basis for measurement of neoepitope fragments of ECM proteins in the blood of 195 consecutive patients with LEAD by specific enzyme-linked immunosorbent assays.

RESULTS

Histologic and proteomic analyses confirmed the structural disorganization of affected arteries. Fourteen of 81 proteins were identified as differentially expressed in diseased arteries with respect to healthy tissues. Most of them were related to ECM components, and the difference in expression was used in multivariate analyses to establish that severe arterial lesions in LEAD patients have a specific proteome. Analysis of neoepitope fragments in blood revealed that fragments of versican and collagen type IV, alone or in combination, segregated patients with mild to moderate symptoms (intermittent claudication, Fontaine I-II) from those with severe LEAD (critical limb ischemia, Fontaine III-IV).

CONCLUSIONS

We propose noninvasive candidate biomarkers with the ability to be clinically useful across the LEAD spectrum.

Galectin-3 in Peripheral Artery Disease. Relationships with Markers of Oxidative Stress and Inflammation

Galectin-3 is a modulator of oxidative stress, inflammation, and fibrogenesis involved in the pathogenesis of vascular diseases. The present study sought to characterize, in patients with peripheral artery disease (PAD), the localization of galectin-3 in arterial tissue, and to analyze the relationships between the circulating levels of galectin-3 and oxidative stress and inflammation. It also sought to compare the diagnostic accuracy of galectin-3 with that of other biochemical markers of this disease. We analyzed femoral or popliteal arteries from 50 PAD patients, and four control arteries. Plasma from 86 patients was compared with that from 72 control subjects. We observed differences in the expression of galectin-3 in normal arteries, and arteries from patients with PAD, with a displacement of the expression from the adventitia to the media, and the intima. In addition, plasma galectin-3 concentration was increased in PAD patients, and correlated with serologic markers of oxidative stress (F2-isoprostanes), and inflammation [chemokine (C−C motif) ligand 2, C-reactive protein, β-2-microglobulin]. We conclude that the determination of galectin-3 has good diagnostic accuracy in the assessment of PAD and compares well with other analytical parameters currently in use.

Biochemical indices of oxidative stress and inflammation in the evaluation of peripheral artery disease

BACKGROUND

The aims of this study were: (1) to investigate changes in indices of oxidative stress and inflammation in the evaluation of peripheral artery disease (PAD); (2) to compare the diagnostic efficacy of these parameters with that of classical clinical laboratory routine parameters.

DESIGN AND METHODS

We studied 115 patients with PAD and 300 healthy volunteers.

RESULTS

PAD patients had significantly increased circulating concentrations of F2-isoprostanes, protein carbonyls, chemokine (C-C motif) ligand 2 (CCL2), high-sensitivity C-reactive protein (hs-CRP), β-2-microglobulin (B2M), and decreased paraoxonase-1 (PON1) levels. When patients were classified according to the Fontaine score, we observed important increases in plasma F2-isoprostanes and CCL2 that appeared in milder stages of the disease, and remained so at similar levels in more advanced stages; almost no overlapping with the control group was noted. Receiver operating characteristics analysis comparing patients and controls revealed that the areas under the curve for F2-isoprostanes and CCL2 approached unity [0.999 (0.998-1.000) and 0.993 (0.985-1.000)], respectively, and significantly higher to those of the other measured parameters.

CONCLUSION

Our data suggest that F2-isoprostanes and CCL2 measurements may be useful tools for the diagnosis of PAD.

Exploring the Process of Energy Generation in Pathophysiology by Targeted Metabolomics: Performance of a Simple and Quantitative Method

Abnormalities in mitochondrial metabolism and regulation of energy balance contribute to human diseases. The consequences of high fat and other nutrient intake, and the resulting acquired mitochondrial dysfunction, are essential to fully understand common disorders, including obesity, cancer, and atherosclerosis. To simultaneously and noninvasively measure and quantify indirect markers of mitochondrial function, we have developed a method based on gas chromatography coupled to quadrupole-time of flight mass spectrometry and an electron ionization interface, and validated the system using plasma from patients with peripheral artery disease, human cancer cells, and mouse tissues. This approach was used to increase sensibility in the measurement of a wide dynamic range and chemical diversity of multiple intermediate metabolites used in energy metabolism. We demonstrate that our targeted metabolomics method allows for quick and accurate identification and quantification of molecules, including the measurement of small yet significant biological changes in experimental samples. The apparently low process variability required for its performance in plasma, cell lysates, and tissues allowed a rapid identification of correlations between interconnected pathways. Our results suggest that delineating the process of energy generation by targeted metabolomics can be a valid surrogate for predicting mitochondrial dysfunction in biological samples. Importantly, when used in plasma, targeted metabolomics should be viewed as a robust and noninvasive source of biomarkers in specific pathophysiological scenarios.