Estradiol-driven metabolism in transwomen associates with reduced circulating extracellular vesicle microRNA-224/452

OBJECTIVE

Sex steroid hormones like estrogens have a key role in the regulation of energy homeostasis and metabolism. In transwomen, gender-affirming hormone therapy like estradiol (in combination with antiandrogenic compounds) could affect metabolism as well. Given that the underlying pathophysiological mechanisms are not fully understood, this study assessed circulating estradiol-driven microRNAs (miRs) in transwomen and their regulation of genes involved in metabolism in mice.

METHODS

Following plasma miR-sequencing (seq) in a transwomen discovery (n = 20) and validation cohort (n = 30), we identified miR-224 and miR-452. Subsequent systemic silencing of these miRs in male C57Bl/6 J mice (n = 10) was followed by RNA-seq-based gene expression analysis of brown and white adipose tissue in conjunction with mechanistic studies in cultured adipocytes.

RESULTS

Estradiol in transwomen lowered plasma miR-224 and -452 carried in extracellular vesicles (EVs) while their systemic silencing in mice and cultured adipocytes increased lipogenesis (white adipose) but reduced glucose uptake and mitochondrial respiration (brown adipose). In white and brown adipose tissue, differentially expressed (miR target) genes are associated with lipogenesis (white adipose) and mitochondrial respiration and glucose uptake (brown adipose).

CONCLUSION

This study identified an estradiol-drive post-transcriptional network that could potentially offer a mechanistic understanding of metabolism following gender-affirming estradiol therapy.

Prediction Power on Cardiovascular Disease of Neuroimmune Guidance Cues Expression by Peripheral Blood Monocytes Determined by Machine-Learning Methods

Atherosclerosis is the underlying pathology in a major part of cardiovascular disease, the leading cause of mortality in developed countries. The infiltration of monocytes into the vessel walls of large arteries is a key denominator of atherogenesis, making monocytes accountable for the development of atherosclerosis. With the development of high-throughput transcriptome profiling platforms and cytometric methods for circulating cells, it is now feasible to study in-depth the predicted functional change of circulating monocytes reflected by changes of gene expression in certain pathways and correlate the changes to disease outcome. Neuroimmune guidance cues comprise a group of circulating- and cell membrane-associated signaling proteins that are progressively involved in monocyte functions. Here, we employed the CIRCULATING CELLS study cohort to classify cardiovascular disease patients and healthy individuals in relation to their expression of neuroimmune guidance cues in circulating monocytes. To cope with the complexity of human datasets featured by noisy data, nonlinearity and multidimensionality, we assessed various machine-learning methods. Of these, the linear discriminant analysis, Naïve Bayesian model and stochastic gradient boost model yielded perfect or near-perfect sensibility and specificity and revealed that expression levels of the neuroimmune guidance cues SEMA6B, SEMA6D and EPHA2 in circulating monocytes were of predictive values for cardiovascular disease outcome.

Sex-specific microRNAs in women with diabetes and left ventricular diastolic dysfunction or HFpEF associate with microvascular injury

Left ventricular diastolic dysfunction (LVDD) and heart failure with preserved ejection fraction (HFpEF) are microcirculation defects following diabetes mellitus (DM). Unrecognized HFpEF is more prevalent in women with diabetes compared to men with diabetes and therefore sex-specific diagnostic strategies are needed. Previously, we demonstrated altered plasma miRs in DM patients with microvascular injury [defined by elevated plasma Angiopoietin-2 (Ang-2) levels]. This study hypothesized the presence of sex-differences in plasma miRs and Ang-2 in diabetic (female) patients with LVDD or HFpEF. After a pilot study, we assessed 16 plasma miRs in patients with LVDD (n = 122), controls (n = 244) and female diabetic patients (n = 10). Subsequently, among these miRs we selected and measured plasma miR-34a, -224 and -452 in diabetic HFpEF patients (n = 53) and controls (n = 52). In LVDD patients, miR-34a associated with Ang-2 levels (R² 0.04, R = 0.21, p = 0.001, 95% CI 0.103–0.312), with plasma levels being diminished in patients with DM, while women with an eGFR < 60 ml/min and LVDD had lower levels of miR-34a, -224 and -452 compared to women without an eGFR < 60 ml/min without LVDD. In diabetic HFpEF women (n = 28), plasma Ang-2 levels and the X-chromosome located miR-224/452 cluster increased compared to men. We conclude that plasma miR-34a, -224 and -452 display an association with the microvascular injury marker Ang-2 and are particularly targeted to women with LVDD or HFpEF.

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).

Long Non-coding RNAs Rian and Miat Mediate Myofibroblast Formation in Kidney Fibrosis

There is an increasing prevalence of chronic kidney disease (CKD), which associates with the development of interstitial fibrosis. Pericytes (perivascular fibroblasts) provide a major source of α-SMA-positive myofibroblasts that are responsible for the excessive deposition of extracellular matrix. In order to identify pericyte long non-coding RNAs (lncRNAs) that could serve as a target to decrease myofibroblast formation and counteract the progression of kidney fibrosis we employed two models of experimental kidney injury, one focused on kidney fibrosis (unilateral ureteral obstruction; UUO), and one focused on acute kidney injury that yields kidney fibrosis in the longer term (unilateral ischemia-reperfusion injury; IRI). This was performed in FoxD1-GC;tdTomato stromal cell reporter mice that allowed pericyte fate tracing. Tomato red-positive FoxD1-derivative cells of control and injured kidneys were FACS-sorted and used for lncRNA and mRNA profiling yielding a distinctive transcriptional signature of pericytes and myofibroblasts with 244 and 586 differentially expressed lncRNAs (>twofold, P < 0.05), in the UUO and IRI models, respectively. Next, we selected two differentially expressed and conserved lncRNAs, Rian (RNA imprinted and accumulated in nucleus) and Miat (Myocardial infarction associated transcript), and explored their potential regulatory role in myofibroblast formation through knockdown of their function with gapmers. While Miat was upregulated in myofibroblasts of UUO and IRI in mice, gapmer silencing of Miat attenuated myofibroblast formation as evidenced by decreased expression of α-SMA, col1α1, SMAD2, and SMAD3, as well as decreased α-SMA and pro-collagen-1α1 protein levels. In contrast, silencing Rian, which was found to be downregulated in kidney myofibroblast after IRI and UUO, resulted in increased myofibroblast formation. In addition, we found microRNAs that were previously linked to Miat (miR-150) and Rian (14q32 miRNA cluster), to be dysregulated in the FoxD1-derivative cells, suggesting a possible interaction between miRNAs and these lncRNAs in myofibroblast formation. Taken together, lncRNAs play a regulatory role in myofibroblast formation, possibly through interacting with miRNA regulation, implicating that understanding their biology and their modulation may have the potential to counteract the development of renal fibrosis.

Silencing of microRNA-132 reduces renal fibrosis by selectively inhibiting myofibroblast proliferation

Chronic kidney disease is associated with progressive renal fibrosis, where perivascular cells give rise to the majority of α-smooth muscle actin (α-SMA) positive myofibroblasts. Here we sought to identify pericytic miRNAs that could serve as a target to decrease myofibroblast formation. Kidney fibrosis was induced in FoxD1-GC;Z/Red-mice by unilateral ureteral obstruction followed by FACS sorting of dsRed-positive FoxD1-derivative cells and miRNA profiling. MiR-132 selectively increased 21-fold during pericyte-to-myofibroblast formation, whereas miR-132 was only 2.5-fold up in total kidney lysates (both in obstructive and ischemia-reperfusion injury). MiR-132 silencing during obstruction decreased collagen deposition (35%) and tubular apoptosis. Immunohistochemistry, Western blot, and qRT-PCR confirmed a similar decrease in interstitial α-SMA(+) cells. Pathway analysis identified a rate-limiting role for miR-132 in myofibroblast proliferation that was confirmed in vitro. Indeed, antagomir-132-treated mice displayed a reduction in the number of proliferating Ki67(+) interstitial myofibroblasts. Interestingly, this was selective for the interstitial compartment and did not impair the reparative proliferation of tubular epithelial cells, as evidenced by an increase in Ki67(+) epithelial cells, as well as increased phospho-RB1, Cyclin-A and decreased RASA1, p21 levels in kidney lysates. Additional pathway and gene expression analyses suggest miR-132 coordinately regulates genes involved in TGF-β signaling (Smad2/Smad3), STAT3/ERK pathways, and cell proliferation (Foxo3/p300). Thus, silencing miR-132 counteracts the progression of renal fibrosis by selectively decreasing myofibroblast proliferation and could potentially serve as a novel antifibrotic therapy.

Circulating microRNAs associate with diabetic nephropathy and systemic microvascular damage and normalize after simultaneous pancreas-kidney transplantation

Because microvascular disease is one of the most important drivers of diabetic complications, early monitoring of microvascular integrity may be of clinical value. By assessing profiles of circulating microRNAs (miRNAs), known regulators of microvascular pathophysiology, in healthy controls and diabetic nephropathy (DN) patients before and after simultaneous pancreas-kidney transplantation (SPK), we aimed to identify differentially expressed miRNAs that associate with microvascular impairment. Following a pilot study, we selected 13 candidate miRNAs and determined their circulating levels in DN (n = 21), SPK-patients (n = 37), healthy controls (n = 19), type 1 diabetes mellitus patients (n = 15) and DN patients with a kidney transplant (n = 15). For validation of selected miRNAs, 14 DN patients were studied longitudinally up to 12 months after SPK. We demonstrated a direct association of miR-25, -27a, -126, -130b, -132, -152, -181a, -223, -320, -326, -340, -574-3p and -660 with DN. Of those, miR-25, -27a, -130b, -132, -152, -320, -326, -340, -574-3p and -660 normalized after SPK. Importantly, circulating levels of some of these miRNAs tightly associate with microvascular impairment as they relate to aberrant capillary tortuosity, angiopoietin-2/angiopoietin-1 ratios, circulating levels of soluble-thrombomodulin and insulin-like growth factor. Taken together, circulating miRNA profiles associate with DN and systemic microvascular damage, and might serve to identify individuals at risk of experiencing microvascular complications, as well as give insight into underlying pathologies.

MicroRNA-155 functions as a negative regulator of RhoA signaling in TGF-β-induced endothelial to mesenchymal transition

Endothelial to mesenchymal transition (EndoMT) has been proposed to be involved in the loss of microvascular capillaries in the pathophysiology of fibrosis and organ failure. In EndoMT, endothelial cells (EC) undergo a mesenchymal transition associated with the loss of cell-cell contacts and the acquisition of a synthetic, contractile phenotype. Here, we sought to identify microRNAs (miRNAs) that could play a central role in regulating EndoMT. In a TGF-β dependent in vitro model for EndoMT, we identified miRNAs that were differentially expressed in normoxic and hypoxic conditions. These studies identified miR-155 to be significantly upregulated in EndoMT, an effect that was enhanced under hypoxia, which further augments EndoMT. Silencing of miR-155 directly increased RhoA expression and activity in endothelial cells and affected phosphorylation of downstream LIMK. In contrast, overexpression of miR-155 counteracted RhoA function. Using a selective Rho kinase inhibitor, we could partly suppress EndoMT, strengthening the notion that RhoA plays a central role in EndoMT. Forced overexpression of miR-155 completely suppressed EndoMT, as evidenced by the maintenance of EC characteristics and blocking the acquisition of a mesenchymal phenotype, as compared to control cells. Our data demonstrate that miRNA-155 functions as a negative regulator of RhoA signaling in TGF-β-induced endothelial to mesenchymal transition.

Aspirin treatment hampers the use of plasma microRNA-126 as a biomarker for the progression of vascular disease

AIMS

MicroRNA-126 (miR-126) facilitates angiogenesis and regulates endothelial cell function. Recent data suggest that miR-126 can serve as a biomarker for vascular disease. Although endothelial cells are enriched for miR-126, platelets also contain miR-126. In this paper, we investigated the contribution of platelets to the pool of miR-126 in plasma of patients with type 2 diabetes (DM2) and how this is affected by aspirin.

METHODS AND RESULTS

In vitro platelet activation resulted in the transfer of miR-126 from the platelet to the plasma compartment, which was prevented by aspirin. In vivo platelet activation, monitored in patients with DM2 by measuring soluble P-selectin, correlated directly with circulating levels of miR-126. The administration of aspirin resulted both in platelet inhibition and concomitantly reduced circulating levels of platelet-derived microRNAs including miR-126.

CONCLUSION

Platelets are a major source of circulating miR-126. Consequently, in patho-physiological conditions associated with platelet activation, such as diabetes type 2, the administration of aspirin may lead to reduced levels of circulating miR-126. Thus, the use of platelet inhibitors should be taken into account when using plasma levels of miR-126 as a biomarker.

Antagomir-mediated silencing of endothelial cell specific microRNA-126 impairs ischemia-induced angiogenesis

MicroRNAs are negative regulators of gene expression that play a key role in cell-type specific differentiation and modulation of cell function and have been proposed to be involved in neovascularization. Previously, using an extensive cloning and sequencing approach, we identified miR-126 to be specifically and highly expressed in human endothelial cells (EC). Here, we demonstrate EC-specific expression of miR-126 in capillaries and the larger vessels in vivo. We therefore explored the potential role of miR-126 in arteriogenesis and angiogenesis. Using miR-reporter constructs, we show that miR-126 is functionally active in EC in vitro and that it could be specifically repressed using antagomirs specifically targeting miR-126. To study the consequences of miR-126 silencing on vascular regeneration, mice were injected with a single dose of antagomir-126 or a control 'scramblemir' and exposed to ischemia of the left hindlimb by ligation of the femoral artery. Although miR-126 was effectively silenced in mice treated with a single, high dose (HD) of antagomir-126, laser Doppler perfusion imaging did not show effects on blood flow recovery. In contrast, quantification of the capillary density in the gastrocnemius muscle revealed that mice treated with a HD of antagomir-126 had a markedly reduced angiogenic response. Aortic explant cultures of the mice confirmed the role of miR-126 in angiogenesis. Our data demonstrate a facilitary function for miR-126 in ischemia-induced angiogenesis and show the efficacy and specificity of antagomir-induced silencing of EC-specific microRNAs in vivo.

Activation of the lectin pathway in murine lupus nephritis

In systemic lupus erythematosus (SLE), hypocomplementaemia and complement deposition have been described both in man and in experimental models. A major involvement of the classical pathway of complement activation has been demonstrated in this disease, however relatively little is known about the involvement of the lectin pathway. Therefore in the present study we have analyzed the activity of all three pathways of complement activation in murine models of SLE. In the mouse, MBL is expressed in two forms, namely MBL-A and MBL-C. In the present study young and old MRL-lpr and control MRL+/+ mice were compared for the levels of complement activity with specific attention for the lectin pathway. It was found that upon aging of both MRL-lpr and MRL+/+ mice, a marked decrease in the activity of the classical pathway (CP) occurs. Levels of alternative pathway (AP) and lectin pathway (LP) activity remain unchanged. Key-molecules of these pathways, C1q, C3, MBL-A and MBL-C were analyzed and were all found to be decreased in aged mice of both strains. The levels of MBL-A and MBL-C showed a high degree of correlation and decreased equally. In aged MRL-lpr mice in which autoimmunity is most pronounced, we observed high autoantibody titers and strong deposition of glomerular immune complexes in association with deposition of C1q, C3, MBL-A and MBL-C. In conclusion, these data suggest that in addition to the classical pathway and the alternative pathway also the lectin pathway of complement activation is involved in murine lupus nephritis.

Anti-C1q autoantibodies deposit in glomeruli but are only pathogenic in combination with glomerular C1q-containing immune complexes

Anti-C1q autoantibodies are present in sera of patients with several autoimmune diseases, including systemic lupus erythematosus (SLE). Strikingly, in SLE the presence of anti-C1q is associated with the occurrence of nephritis. We have generated mouse anti-mouse C1q mAb's and used murine models to investigate whether anti-C1q autoantibodies actually contribute to renal pathology in glomerular immune complex disease. Administration of anti-C1q mAb JL-1, which recognizes the collagen-like region of C1q, resulted in glomerular deposition of C1q and anti-C1q autoantibodies and mild granulocyte influx, but no overt renal damage. However, combination of JL-1 with a subnephritogenic dose of C1q-fixing anti-glomerular basement membrane (anti-GBM) antibodies enhanced renal damage characterized by persistently increased levels of infiltrating granulocytes, major histological changes, and increased albuminuria. This was not observed when a non-C1q-fixing anti-GBM preparation was used. Experiments with different knockout mice showed that renal damage was dependent not only on glomerular C1q and complement activation but also on Fcgamma receptors. In conclusion, anti-C1q autoantibodies deposit in glomeruli together with C1q but induce overt renal disease only in the context of glomerular immune complex disease. This provides an explanation why anti-C1q antibodies are especially pathogenic in patients with SLE.

Anti-C1q autoantibodies deposit in glomeruli but are only pathogenic in combination with glomerular C1q-containing immune complexes

Anti-C1q autoantibodies are present in sera of patients with several autoimmune diseases, including systemic lupus erythematosus (SLE). Strikingly, in SLE the presence of anti-C1q is associated with the occurrence of nephritis. We have generated mouse anti-mouse C1q mAb's and used murine models to investigate whether anti-C1q autoantibodies actually contribute to renal pathology in glomerular immune complex disease. Administration of anti-C1q mAb JL-1, which recognizes the collagen-like region of C1q, resulted in glomerular deposition of C1q and anti-C1q autoantibodies and mild granulocyte influx, but no overt renal damage. However, combination of JL-1 with a subnephritogenic dose of C1q-fixing anti-glomerular basement membrane (anti-GBM) antibodies enhanced renal damage characterized by persistently increased levels of infiltrating granulocytes, major histological changes, and increased albuminuria. This was not observed when a non-C1q-fixing anti-GBM preparation was used. Experiments with different knockout mice showed that renal damage was dependent not only on glomerular C1q and complement activation but also on Fcgamma receptors. In conclusion, anti-C1q autoantibodies deposit in glomeruli together with C1q but induce overt renal disease only in the context of glomerular immune complex disease. This provides an explanation why anti-C1q antibodies are especially pathogenic in patients with SLE.

Anti-C1q autoantibodies in murine lupus nephritis

Autoantibodies against C1q can be found in the circulation of patients with several autoimmune diseases including systemic lupus erythematosus (SLE). In SLE there is an association between the occurrence of these antibodies and renal involvement. How anti-C1q autoantibodies contribute to renal disease is currently unknown. Cohorts of MRL-lpr mice, which are known to develop age-dependent SLE-like disease, were used to study the relationship between levels of anti-C1q autoantibodies and renal disease. We collected serum, urine and renal tissue and analysed autoantibodies, complement levels and renal deposition as well as renal function. At 2 months of age all mice already had elevated levels of anti-C1q autoantibodies, and elution of kidneys revealed the presence of these antibodies in renal immune deposits in MRL-lpr mice and not in control MRL+/+ mice. In conclusion, anti-C1q antibodies are already present in serum and immune deposits of the kidney early in life and therefore can play a role in nephritis during experimental SLE-like disease in mice.

Immune deposition of C1q and anti-C1q antibodies in the kidney is dependent on the presence of glomerular IgG

Anti-C1q autoantibodies are found frequently in patients with Systemic Lupus Erythematosus (SLE) and several studies indicate that these autoantibodies are associated with renal involvement. We have shown earlier that administration of anti-C1q antibodies to normal BALB/c mice results in the deposition of these antibodies and C1q in the kidney. In the present study we have investigated which factors are essential for this C1q-anti-C1q deposition. Injection of anti-C1q antibodies in C57BL/6 mice results in deposition of both C1q and anti-C1q in glomeruli, while administration of equal concentrations of anti-C1q to immunoglobulin deficient Rag2-/- mice did not result in deposition of anti-C1q antibodies. Analysis of renal sections of naive Rag2-/- mice revealed absence of mouse IgG and C1q in the glomeruli, while circulating C1q was within normal levels. Reconstitution of Rag2-/- mice with IgG, either by injection with purified mouse IgG or by splenocyte transfer, resulted in restored localization of mouse IgG together with C1q in the kidney. Subsequent injection of anti-C1q antibodies in these IgG reconstituted mice resulted in clear deposition of C1q together with anti-C1q in the kidneys comparable to that found in C57BL/6 mice receiving anti-C1q. We propose that the continuous presence of serum derived non-immune IgG in the glomerulus serves as a target for low affinity interactions with C1q, which then can serve as antigen for anti-C1q antibodies. Therefore we hypothesize that high and fluctuating levels of IgG as observed in patients with SLE may contribute to flares of renal inflammation in those patients with anti-C1q autoantibodies.

Glomerular deposition of C1q and anti-C1q antibodies in mice following injection of antimouse C1q antibodies

Anti-C1q autoantibodies are present in the serum of patients with different autoimmune diseases such as systemic lupus erythematosus (SLE). The occurrence of these autoantibodies correlates with renal involvement. In the present study we examined whether injection of rabbit antimouse C1q antibodies in mice leads to deposition in kidneys. Injection of healthy mice with a single dose of rabbit IgG antimouse C1q antibodies resulted in deposition of both C1q and IgG anti-C1q in glomeruli. The pattern of deposition observed in the glomeruli of mice injected with antimouse C1q antibodies both at 24 h and 2 weeks was both glomerular basement membrane (GBM)-associated and mesangial. Injection of control IgG did not have a detectable effect on circulating C1q levels, and no deposition of either C1q or rabbit IgG was seen at 24 h. The deposition of rabbit antimouse C1q and C1q in glomeruli resulted in complement activation, as assessed by C3 deposition, and influx of leucocytes associated with albuminuria in some, but not all mice. In none of the control mice was albuminuria observed. This report is the first to show that anti-C1q antibodies deposit in the healthy glomerulus together with autologous C1q. This deposition is stable for at least 2 weeks, causes complement activation, leucocyte influx and can lead to mild albuminuria.