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Association of lipoarabinomannan with high density lipoprotein in blood: implications for diagnostics.

ABSTRACT: Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We have also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum, and demonstrate that the circulating concentrations of 'monomeric' LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. This phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host-pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics.

SUBMITTER: Sakamuri RM

PROVIDER: S-EPMC3807251 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

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Association of lipoarabinomannan with high density lipoprotein in blood: implications for diagnostics.

Sakamuri Rama Murthy RM Price Dominique N DN Lee Myungsun M Cho Sang Nae SN Barry Clifton E CE Via Laura E LE Swanson Basil I BI Mukundan Harshini H

Tuberculosis (Edinburgh, Scotland) 20130316 3

Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We have also applied an ultra-sensitive detection strategy developed fo ...[more]

PMID: 23507184

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Project description:Lipoarabinomannan (LAM), an amphiphilic lipoglycan of the Mycobacterium tuberculosis cell wall, is a diagnostic target for tuberculosis. Previous work from our laboratory and others suggests that LAM is associated with host serum lipoproteins, which may in turn have implications for diagnostic assays. Our team has developed two serum assays for amphiphile detection: lipoprotein capture and membrane insertion. The lipoprotein capture assay relies on capture of the host lipoproteins, exploiting the biological association of host lipoprotein with microbial amphiphilic biomarkers to "concentrate" LAM. In contrast, the membrane insertion assay is independent of the association between pathogen amphiphiles and host lipoprotein association, and directly captures LAM based on its thermodynamic propensity for association with a supported lipid membrane, which forms the functional surface of an optical biosensor. In this manuscript, we explored the use of these assays for the detection of LAM in sera from adults whose tuberculosis status had been well-characterized using conventional microbiological tests, and endemic controls. Using the lipoprotein capture assay, LAM signal/noise ratios were >1.0 in 29/35 (83%) individuals with culture-confirmed active tuberculosis, 8/13 (62%) individuals with tuberculosis symptoms, but no positive culture for M. tuberculosis, and 0/6 (0%) symptom-free endemic controls. To evaluate serum LAM levels without bias associated with potential differences in circulating host lipoprotein concentrations between individuals, we subsequently processed available samples to liberate LAM from associated host lipoprotein assemblies followed by direct detection of the pathogen biomarker using the membrane insertion approach. Using the membrane insertion assay, signal/noise for detection of serum LAM was greater than that observed using the lipoprotein capture method for culture-confirmed TB patients (6/6), yet remained negative for controls (2/2). Taken together, these results suggest that detection of serum LAM is a promising TB diagnostic approach, but that further work is required to optimize assay performance and to decipher the implications of LAM/host lipoprotein associations for diagnostic assay performance and TB pathogenesis.

Project description:Background and objectiveKlotho is a protein that is closely related to human aging. Soluble Klotho (S-Klotho) is a circulating protein, and its level decreases in response to systemic inflammation. The relationship between the platelet/high-density lipoprotein cholesterol ratio (PHR), an emerging inflammatory index, and S-Klotho concentrations is still unclear. In addition, the mean platelet volume has been confirmed to have a significant negative association with S-Klotho concentrations, but the relationship between the platelet count (PC) and S-Klotho concentrations has not yet been reported.MethodsData from individuals who participated in the National Health and Nutrition Examination Survey (NHANES) during the five cycles from 2007 to 2016 were retrieved for analysis. Linear regression, two-piecewise linear regression, and restricted cubic spline (RCS) methods were used to analyze the associations of the PHR index and its components with S-Klotho concentrations. In addition, subgroup analysis and effect modification tests were conducted.ResultsA total of 11,123 participants (5463 men (48.17%)), with an average age of 56.2 years, were included. After full adjustment, the S-Klotho levels of participants in the highest quartile group of PHR (β: -51.19, 95% CI: -75.41 to -26.97, P < 0.001) and the highest quartile group of PC (β: -72.34, 95% CI: -93.32 to -51.37, P < 0.0001) were significantly lower than those in their respective lowest quartile groups, and a significant downward trend was presented among the four groups (P for trend < 0.05, respectively). However, high-density lipoprotein cholesterol (HDL-C) concentrations were not significantly associated with S-Klotho concentrations. RCS revealed that the PHR and PC were nonlinearly associated with S-Klotho concentrations; two-piecewise linear regression revealed that the inflection points were 175.269 and 152, respectively, and that these associations slightly weakened after the inflection point. According to the subgroup analysis, liver disease status enhanced the association between the PC and S-Klotho concentrations.ConclusionsBoth the PHR and PC were significantly negatively associated with S-Klotho concentrations, and these associations were nonlinear. There was no significant association between HDL-C and S-Klotho concentrations. Liver disease status enhances the negative association between the PC and S-Klotho concentrations, and the specific mechanism deserves further exploration.

Project description:BackgroundIncreasing evidence showed that carbamylated lipoprotein accelerated atherosclerosis. However, whether such modification of high-density lipoprotein (HDL) particles alters in type 2 diabetes mellitus (T2DM) patients and facilitates vascular complications remains unclear. We aimed to investigate the alteration of the carbamylation in HDL among T2DM patients and clarify its potential role in atherogenesis.MethodsA total of 148 consecutive T2DM patients undergoning angiography and 40 age- and gender-matched control subjects were included. HDL was isolated from plasma samples, and the concentration of HDL carbamyl-lysine (HDL-CBL) was measured. Furthermore, the HDL from subjects and in-vitro carbamylated HDL (C-HDL) was incubated with endothelial cells and monocyte to endothelial cell adhesion. Adhesion molecule expression and signaling pathway were detected.ResultsCompared with the control group, the HDL-CBL level was remarkably increased in T2DM patients (6.13 ± 1.94 vs 12.00 ± 4.06 (ng/mg), P < 0.001). Of note, HDL-CBL demonstrated a more significant increase in T2DM patients with coronary artery disease (CAD) (n = 102) than those without CAD (n = 46) (12.75 ± 3.82 vs. 10.35 ± 4.11(ng/mg), P = 0.001). Multivariate logistic regression analysis demonstrated that higher HDL-CBL level was independently associated with a higher prevalence of CAD in diabetic patients after adjusting for established cofounders (adjusted odds ratio 1.174, 95% confidence Interval 1.045-1.319, p = 0.017). HDL from diabetic patients with CAD enhanced greater monocyte adhesion than that from the non-CAD or the control group (P < 0.001). Such pro-atherogenic capacity of diabetic HDL positively correlated with HDL-CBL level. Furthermore, in-vitro incubation of carbamylated HDL (C-HDL) with endothelial promoted monocyte to endothelial cell adhesion, induced upregulation of cell adhesion molecules expression, and activated NF-κB/p65 signaling in endothelial cells. Inhibiting carbamylation of HDL or NF-κB activation attenuated the monocyte to endothelial cell adhesion and cell surface adhesion molecules expression.ConclusionsOur study identified elevated carbamylation modification of HDL from T2DM patients, especially in those with concomitant CAD. We also evidenced that C-HDL enhanced monocyte to endothelial cell adhesion, indicating a potential pro-atherogenic role of C-HDL in atherosclerosis among T2DM patients. Trial registration https://register.clinicaltrials.gov , NCT04390711 Registered on 14 May 2020; Retrospectively registered.

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Association of lipoarabinomannan with high density lipoprotein in blood: implications for diagnostics.

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Association of lipoarabinomannan with high density lipoprotein in blood: implications for diagnostics.

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