Evaluation of Biomarkers in Sepsis: High Dimethylarginine (ADMA and SDMA) Concentrations Are Associated with Mortality

Association of Asymmetric and Symmetric Dimethylarginine with Inflammation in the Population-Based Study of Health in Pomerania

The amino acids arginine (Arg), asymmetric (ADMA) and symmetric dimethylarginine (SDMA) are related to nitric oxide (NO) metabolism and potential markers of two different disease entities: cardiovascular disease such as atherosclerosis and systemic inflammation in critically ill patients with sepsis. Although very different in their pathophysiological genesis, both entities involve the functional integrity of blood vessels. In this context, large population-based data associating NO metabolites with proinflammatory markers, e.g., white blood cell count (WBC), high-sensitivity C-reactive protein (hsCRP), and fibrinogen, or cytokines are sparse. We investigated the association of Arg, ADMA and SDMA with WBC, hsCRP, and fibrinogen in 3556 participants of the Study of Health in Pomerania (SHIP)-TREND study. Furthermore, in a subcohort of 456 subjects, 31 inflammatory markers and cytokines were analyzed. We identified Arg and SDMA to be positively associated with hsCRP (β coefficient 0.010, standard error (SE) 0.002 and 0.298, 0.137, respectively) as well as fibrinogen (β 5.23 × 10-3, SE 4.75 × 10-4 and 0.083, 0.031, respectively). ADMA was not associated with WBC, hsCRP, or fibrinogen. Furthermore, in the subcohort, Arg was inversely related to a proliferation-inducing ligand (APRIL). SDMA was positively associated with osteocalcin, tumor necrosis factor receptor 1 and 2, and soluble cluster of differentiation 30. Our findings provide new insights into the involvement of Arg, ADMA, and SDMA in subclinical inflammation in the general population.

Metabolomic markers mediate erythrocyte anisocytosis in older adults: Results from three independent aging cohorts

BACKGROUND

Anisocytosis reflects unequal-sized red blood cells and is quantified using red blood cell distribution width (RDW). RDW increases with age and has been consistently associated with adverse health outcomes, such as cardiovascular disease and mortality. Why RDW increases with age is not understood. We aimed to identify plasma metabolomic markers mediating anisocytosis with aging.

METHODS

We performed mediation analyses of plasma metabolomics on the association between age and RDW using resampling techniques after covariate adjustment. We analyzed data from adults aged 70 or older from the main discovery cohort of the Baltimore Longitudinal Study of Aging (BLSA, n = 477, 46% women) and validation cohorts of the Health, Aging and Body Composition Study (Health ABC, n = 620, 52% women) and Invecchiare in Chianti, Aging in the Chianti Area (InCHIANTI) study (n = 735, 57% women). Plasma metabolomics was assayed using the Biocrates MxP Quant 500 kit in BLSA and Health ABC and liquid chromatography with tandem mass spectrometry in InCHIANTI.

RESULTS

In all three cohorts, symmetric dimethylarginine (SDMA) significantly mediated the association between age and RDW. Asymmetric dimethylarginine (ADMA) and 1-methylhistidine were also significant mediators in the discovery cohort and one validation cohort. In the discovery cohort, we also found choline, homoarginine, and several long-chain triglycerides significantly mediated the association between age and RDW.

CONCLUSIONS AND RELEVANCE

This metabolomics study of three independent aging cohorts identified a specific set of metabolites mediating anisocytosis with aging. Whether SDMA, ADMA, and 1-methylhistidine are released by the damaged erythrocytes with high RDW or they affect the physiology of erythrocytes causing high RDW should be further investigated.

A new perspective on NO pathway in sepsis and ADMA lowering as a potential therapeutic approach

The nitric oxide pathway plays a critical role in vascular homeostasis. Increased levels of systemic nitric oxide (NO) are observed in preclinical models of sepsis and endotoxemia. This has led to the postulation that vasodilation by inducible nitric oxide synthase (iNOS) generated NO may be a mechanism of hypotension in sepsis. However, contrary to the expected pharmacological action of a nitric oxide synthase (NOS) inhibitor, clinical studies with L-NAME produced adverse cardiac and pulmonary events, and higher mortality in sepsis patients. Thus, the potential adverse effects of NO in human sepsis and shock have not been fully established. In recent years, the emerging new understanding of the NO pathway has shown that an endogenously produced inhibitor of NOS, asymmetric dimethylarginine (ADMA), a host response to infection, may play an important role in the pathophysiology of sepsis as well as organ damage during ischemia–reperfusion. ADMA induces microvascular dysfunction, proinflammatory and prothrombotic state in endothelium, release of inflammatory cytokines, oxidative stress and mitochondrial dysfunction. High levels of ADMA exist in sepsis patients, which may produce adverse effects like those observed with L-NAME. Several studies have demonstrated the association of plasma ADMA levels with mortality in sepsis patients. Preclinical studies in sepsis and ischemia–reperfusion animal models have shown that lowering of ADMA reduced organ damage and improved survival. The clinical finding with L-NAME and the preclinical research on ADMA “bed to bench” suggest that ADMA lowering could be a potential therapeutic approach to attenuate progressive organ damage and mortality in sepsis. Testing of this approach is now feasible by using the pharmacological molecules that specifically lower ADMA.

Aberrant blood MALT1 and its relevance with multiple organic dysfunctions, T helper cells, inflammation, and mortality risk of sepsis patients

Background

MALT1 is linked with multiple organic dysfunctions, inflammatory storm, and T helper (Th) cell differentiation. Herein, the current study aimed to investigate the correlation of peripheral blood mononuclear cell (PBMC) MALT1 with Th1 cells, Th17 cells, and prognosis of sepsis patients.

Methods

In general, 78 sepsis patients and 40 health controls (HCs) were enrolled. MALT1 expression was detected in PBMCs from all subjects by RT‐qPCR. Besides, Th1 and Th17 cells were measured in PBMCs from sepsis patients by flow cytometry; interleukin 17A (IL‐17A) and interferon gamma (IFN‐γ) were determined in serum from sepsis patients by ELISA.

Results

MALT1 expression was higher in sepsis patients than HCs (p < 0.001). MALT1 expression was positively correlated with Th17 cells (r_s = 0.291, p = 0.038) and IL‐17A (r_s = 0.383, p = 0.001), but not with Th1 cells (r_s = 0.204, p = 0.151) or IFN‐γ (r_s = 0.175, p = 0.125) in sepsis patients. MALT1 expression was positively correlated with APACHE II score (r_s = 0.275, p = 0.015), C‐reactive protein (CRP) (r_s = 0.257, p = 0.023), and sequential organ failure assessment (SOFA) score (r_s = 0.306, p = 0.006) (MALT1 expression was positively correlated with SOFA respiratory system score (r_s = 0.348, p = 0.002), and SOFA liver score (r_s = 0.260, p = 0.021), but not with SOFA scores in nervous system, cardio vascular system, coagulation, and renal system (all p > 0.05)). MALT1 expression (p = 0.010), Th1 cells (p = 0.010), Th17 cells (p = 0.038), and IL‐17A (p = 0.012), except for IFN‐γ (p = 0.102), elevated in sepsis deaths compared with sepsis survivors.

Conclusion

PBMC MALT1 is highly expressed in sepsis patients with its overexpression associated with multiple organic dysfunctions, elevated Th17 cells, and increased mortality risk.

A Therapeutic Extracorporeal Device for Specific Removal of Pathologic Asymmetric Dimethylarginine from the Blood

INTRODUCTION

Blood levels of uremic toxin, asymmetric dimethylarginine (ADMA), are strongly associated with mortality in sepsis, renal failure, and cardiovascular and renal disease patients.

METHODS

An extracorporeal approach to reduce pathological ADMA was developed. The dimethylarginine dimethylaminohydrolase (DDAH) was immobilized on agarose beads to prepare a cartridge. The efficacy of cartridge for ADMA lowering in blood was investigated.

RESULTS

The DDAH beads and cartridge reduced ADMA from solution or plasma. The magnitude of ADMA removal was dependent on the quantity of DDAH linked to the beads and the flow rate. When tested in association with plasmapheresis, the DDAH-cartridge was highly effective in ADMA removal from the blood and improved the arginine/ADMA ratio in a pig model.

CONCLUSION

A new, safe, and effective extracorporeal approach to lower ADMA was developed which may have application in improving outcomes in patients with vascular complications and risk of mortality associated with high ADMA.