Diabetic Nephropathy Alters the Distribution of Circulating Angiogenic MicroRNAs Among Extracellular Vesicles, HDL, and Ago-2

Previously, we identified plasma microRNA (miR) profiles that associate with markers of microvascular injury in patients with diabetic nephropathy (DN). However, miRs circulate in extracellular vesicles (EVs) or in association with HDL or the RNA-binding protein argonaute-2 (Ago-2). Given that the EV- and HDL-mediated miR transfer toward endothelial cells (ECs) regulates cellular quiescence and inflammation, we hypothesized that the distribution of miRs among carriers affects microvascular homeostasis in DN. Therefore, we determined the miR expression in EV, HDL, and Ago-2 fractions isolated from EDTA plasma of healthy control subjects, patients with diabetes mellitus (DM) with or without early DN (estimated glomerular filtration rate [eGFR] >30 mL/min/1.73 m²), and patients with DN (eGFR <30 mL/min/1.73 m²). Consistent with our hypothesis, we observed alterations in miR carrier distribution in plasma of patients with DM and DN compared with healthy control subjects. Both miR-21 and miR-126 increased in EVs of patients with DN, whereas miR-660 increased in the Ago-2 fraction and miR-132 decreased in the HDL fraction. Moreover, in vitro, differentially expressed miRs improved EC barrier formation (EV-miR-21) and rescued the angiogenic potential (HDL-miR-132) of ECs cultured in serum from patients with DM and DN. In conclusion, miR measurement in EVs, HDL, and Ago-2 may improve the biomarker sensitivity of these miRs for microvascular injury in DN, while carrier-specific miRs can improve endothelial barrier formation (EV-miR-21/126) or exert a proangiogenic response (HDL-miR-132).

Distinct fecal and oral microbiota composition in human type 1 diabetes, an observational study

OBJECTIVE

Environmental factors driving the development of type 1 diabetes (T1D) are still largely unknown. Both animal and human studies have shown an association between altered fecal microbiota composition, impaired production of short-chain fatty acids (SCFA) and T1D onset. However, observational evidence on SCFA and fecal and oral microbiota in adults with longstanding T1D vs healthy controls (HC) is lacking.

RESEARCH DESIGN AND METHODS

We included 53 T1D patients without complications or medication and 50 HC matched for age, sex and BMI. Oral and fecal microbiota, fecal and plasma SCFA levels, markers of intestinal inflammation (fecal IgA and calprotectin) and markers of low-grade systemic inflammation were measured.

RESULTS

Oral microbiota were markedly different in T1D (eg abundance of Streptococci) compared to HC. Fecal analysis showed decreased butyrate producing species in T1D and less butyryl-CoA transferase genes. Also, plasma levels of acetate and propionate were lower in T1D, with similar fecal SCFA. Finally, fecal strains Christensenella and Subdoligranulum correlated with glycemic control, inflammatory parameters and SCFA.

CONCLUSIONS

We conclude that T1D patients harbor a different amount of intestinal SCFA (butyrate) producers and different plasma acetate and propionate levels. Future research should disentangle cause and effect and whether supplementation of SCFA-producing bacteria or SCFA alone can have disease-modifying effects in T1D.

High-density lipoprotein profiling changes in patients with rheumatoid arthritis treated with tumor necrosis factor inhibitors: a cohort study

OBJECTIVE

We investigated changes in high-density lipoprotein (HDL) profiling in patients with rheumatoid arthritis who started treatment by taking tumor necrosis factor (TNF) inhibitors. The patients were stratified for European League Against Rheumatism (EULAR) response.

METHODS

A group of 100 patients naive for TNF inhibitors at baseline were randomly selected from 204 adalimumab-treated and 203 etanercept-treated patients on the basis of their EULAR response. HDL profiling was measured using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

In EULAR good responders, mass charged markers representing serum amyloid A (SAA-1 and -2) decreased significantly after 4 months' therapy. There were no significant differences in HDL profiling in EULAR nonresponders.

CONCLUSION

Effective suppression of inflammation with TNF inhibitors results in favorable changes in HDL composition.

Proteinuria in early childhood due to familial LCAT deficiency caused by loss of a disulfide bond in lecithin:cholesterol acyl transferase

INTRODUCTION

Familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) is a rare recessive disorder of cholesterol metabolism characterized by the absence of high density lipoprotein (HDL) and the triad of corneal opacification, hemolytic anemia and glomerulopathy.

PATIENTS

We here report on FLD in three siblings of a kindred of Moroccan descent with HDL deficiency. In all cases (17, 12 and 3 years of age) corneal opacification and proteinuria were observed. In the 17-year-old female proband, anemia with target cells was observed.

RESULTS

Homozygosity for a mutation in LCAT resulted in the exchange of cysteine to tyrosine at position 337, disrupting the second disulfide bond in LCAT. LCAT protein and activity were undetectable in the patients' plasma and in media of COS7 cells transfected with an expression vector with mutant LCAT cDNA. Upon treatment with an ACE inhibitor and a thiazide diuretic, proteinuria in the proband decreased from 6g to 2g/24h.

CONCLUSION

This is the first report that FLD can cause nephropathy at a very early age.

Enhanced atherogenesis and altered high density lipoprotein in patients with Crohn's disease

A chronic inflammatory state is a risk factor for accelerated atherogenesis. The aim of our study was to explore whether Crohn's disease (CD), characterized by recurrent inflammatory episodes, is also associated with accelerated atherogenesis. In 60 CD patients and 122 matched controls, carotid intima media thickness (IMT), a validated marker for the burden and progression of atherosclerosis, was assessed ultrasonographically. Additional subgroup analyses, including plasma levels of acute phase reactants and HDL protein profiling, were performed in 11 consecutive patients with CD in remission, 10 patients with active CD, and 15 healthy controls. Carotid IMT in patients with CD was increased compared with healthy volunteers: 0.71 (0.17) versus 0.59 (0.14) mm (P < 0.0001), respectively. In the subgroup analysis, HDL levels in controls and patients in remission were identical [(1.45 (0.48) and 1.40 (0.46) mmol/l; P = 0.797], whereas HDL during exacerbation was profoundly reduced: 1.02 (0.33) (P = 0.022). HDL from patients with active CD and CD patients in remission was characterized by a reduced ability to attenuate oxidation compared with controls (P = 0.008 and P = 0.024 respectively). Patients with CD have increased IMT compared with matched controls, indicative of accelerated atherogenesis. The changes during CD exacerbation in terms of HDL concentration and composition imply a role for impaired HDL protection in these patients.

Apolipoprotein A-V: a novel apolipoprotein associated with an early phase of liver regeneration

Liver regeneration in response to various forms of liver injury is a complex process, which ultimately results in restoration of the original liver mass and function. Because the underlying mechanisms that initiate this response are still incompletely defined, this study was aimed to identify novel factors. Liver genes that were up-regulated 6 h after 70% hepatectomy (PHx) in the rat were selected by cDNA subtractive hybridization. Besides known genes associated with cell proliferation, several novel genes were isolated. The novel gene that was most up-regulated was further studied. Its mRNA showed a liver-specific expression and encoded a protein comprising 367 amino acids. The mouse and human cDNA analogues were also isolated and appeared to be highly homologous. The human gene analogue was located at an apolipoprotein gene cluster on chromosome 11q23. The protein encoded by this gene had appreciable homology with apolipoproteins A-I and A-IV. Maximal expression of the gene in the rat liver and its gene product in rat plasma was observed 6 h after PHx. The protein was present in plasma fractions containing high density lipoprotein particles. Therefore, we have identified a novel apolipoprotein, designated apolipoprotein A-V, that is associated with an early phase of liver regeneration.

Distribution and kinetics of lipoprotein-bound endotoxin

Lipopolysaccharide (LPS), the major glycolipid component of gram-negative bacterial outer membranes, is a potent endotoxin responsible for pathophysiological symptoms characteristic of infection. The observation that the majority of LPS is found in association with plasma lipoproteins has prompted the suggestion that sequestering of LPS by lipid particles may form an integral part of a humoral detoxification mechanism. Previous studies on the biological properties of isolated lipoproteins used differential ultracentrifugation to separate the major subclasses. To preserve the integrity of the lipoproteins, we have analyzed the LPS distribution, specificity, binding capacity, and kinetics of binding to lipoproteins in human whole blood or plasma by using high-performance gel permeation chromatography and fluorescent LPS of three different chemotypes. The average distribution of O111:B4, J5, or Re595 LPS in whole blood from 10 human volunteers was 60% (+/-8%) high-density lipoprotein (HDL), 25% (+/-7%) low-density lipoprotein, and 12% (+/-5%) very low density lipoprotein. The saturation capacity of lipoproteins for all three LPS chemotypes was in excess of 200 microg/ml. Kinetic analysis however, revealed a strict chemotype dependence. The binding of Re595 or J5 LPS was essentially complete within 10 min, and subsequent redistribution among the lipoprotein subclasses occurred to attain similar distributions as O111:B4 LPS at 40 min. We conclude that under simulated physiological conditions, the binding of LPS to lipoproteins is highly specific, HDL has the highest binding capacity for LPS, the saturation capacity of lipoproteins for endotoxin far exceeds the LPS concentrations measured in clinical situations, and the kinetics of LPS association with lipoproteins display chemotype-dependent differences.