Biology subjects

Pineda-Torra, I.

Publications and source records attributed to Pineda-Torra, I..

7 recordsLinked to original sources

bioRxiv2026

An enhancer-centric approach applied to human immune system epigenomes revealed the association of macrophage enhancers with cardiovascular disease

Complex diseases are influenced by both genetic and environmental factors. Immune cells are key mediating interactions with the environment, but the impact of genetic variation on the immune system and how it influences complex diseases is not fully understood. Moreover, most genome-wide analyses (GWAS) variants associated with complex diseases are non-coding and difficult to interpret. Here, we investigated the association of non-coding variants with immune cell enhancers. As part of BLUEPRINT and the International Human Epigenome (IHEC) consortia, we generated and analysed a comprehensive set of epigenomes for human primary immune cells, including 107 epigenomes derived from 749 ChIP-Seq experiments across 24 cell types. We identified multicell enhancer activity patterns across the genome and examined their links with non-coding variants from 518 GWAS traits. This analysis revealed 117 significant associations, including novel links between cardiovascular disease variants and macrophage-specific enhancers that regulate genes involved in lipid metabolism and immunity, such as the gene encoding for the nuclear receptor LXR-alpha (NR1H3) and many of its known target genes. Together, these data will help to better understand the influence of genetic variability in immune function and related diseases.

genomics↗

bioRxiv2020

Inhibiting LXRα Phosphorylation in Hematopoietic Cells Reduces Inflammation and Attenuates Atherosclerosis and Obesity

Atherosclerosis and obesity share pathological features including inflammation mediated by innate and adaptive immune cells. LXR, a nuclear receptor, plays a central role in the transcription of inflammatory and lipid metabolic genes. LXR is modulated by phosphorylation at serine 196 (LXR pS196), however, the functional consequences of LXR pS196 in hematopoietic cell precursors in atherosclerosis and obesity have not been investigated. To assess the importance of LXR phosphorylation, bone marrow from LXRWT and S196A mice was transplanted into Ldlr-/- mice, which were fed a high fat, high cholesterol diet prior to evaluation of atherosclerosis and obesity. Plaques from S196A mice showed reduced inflammatory monocyte recruitment, lipid accumulation, and macrophage proliferation. Expression profiling of CD68+ cells from S196A mouse plaques revealed downregulation of pro-inflammatory genes and upregulation of mitochondrial genes characteristic of anti-inflammatory macrophages. Furthermore, S196A mice had lower body weight and less visceral adipose tissue; this was associated with transcriptional reprograming of the adipose tissue macrophages and resolution of inflammation resulting in less fat accumulation within adipocytes. Thus, reducing LXR pS196 in hematopoietic cells attenuates atherosclerosis and obesity by reprogramming the transcriptional activity of LXR to an anti-inflammatory phenotype.

molecular biology↗

bioRxiv2019

Sex differences in autoimmunity could be associated with altered regulatory T cell phenotype and lipoprotein metabolism

Male and female immune responses are known to differ resulting in an increased prevalence of autoimmunity in women. Here sex differences in T-cell subset frequency and function during adolescence were examined in healthy donors and patients with the autoimmune disease juvenile (J)SLE; onset of JSLE commonly occurs during puberty suggesting a strong hormonal influence. Healthy adolescent males had increased regulatory T-cell (Treg) frequency, and increased Treg suppressive capacity and IL-4 production compared to healthy adolescent females. The T-helper 2-like profile in male Tregs was associated with increased expression of GATA3 which correlated significantly with elevated Treg plasma membrane glycosphingolipid expression. Differential Treg phenotype was associated with unique serum metabolomic profiles in males compared to female adolescents. Notably, very low density lipoprotein (VLDL) metabolomic signatures correlated positively with activated Tregs in males but with resting Tregs in females. Consistently, only VLDL isolated from male serum was able to induce increased Treg IL-4 production and glycosphingolipid expression following in cultured cells. Remarkably, gender differences in Treg frequency, phenotype and function and serum metabolomic profiles were lost in adolescents with JSLE. This work provides evidence that a combination of pubertal development, immune cell defects and dyslipidemia may contribute to JSLE pathogenesis.

immunology↗

bioRxiv2019

Activation of the liver X receptors alters CD4+ T cell membrane lipids and signalling through direct regulation of glycosphingolipid synthesis

The liver X receptor (LXR) is a key transcriptional regulator of cholesterol, fatty acid, and phospholipid metabolism. Dynamic remodeling of immunometabolic pathways, including lipid metabolism, is a crucial step in T cell activation. Here we explored the role of LXR-regulated metabolic processes in primary human CD4+ T cells, and their role in controlling plasma membrane lipids (glycosphingolipids and cholesterol) which strongly influence T cell immune signaling and function. Crucially, we identified the glycosphingolipid biosynthesis enzyme glucosylceramide synthase (UGCG) as a direct transcriptional LXR target. LXR activation by agonist GW3965 or endogenous oxysterol ligands significantly altered the glycosphingolipid:cholesterol balance in the plasma membrane by increasing glycosphingolipid levels and reducing cholesterol. Consequently, LXR activation lowered plasma membrane lipid order (stability), and an LXR antagonist could block this effect. LXR stimulation also reduced lipid order at the immune synapse and accelerated activation of proximal T cell signaling molecules. Ultimately, LXR activation dampened pro-inflammatory T cell function. Finally, compared to responder T cells, regulatory T cells had a distinct pattern of LXR-target gene expression corresponding to reduced lipid order. This suggests LXR-driven lipid metabolism could contribute to functional specialization of these T cell subsets. Overall, we report a novel mode of action for LXR in T cells involving the regulation of glycosphingolipid and cholesterol metabolism, and demonstrate its relevance in modulating T cell function.

immunology↗

bioRxiv2018

Aged insulin resistant macrophages reveal dysregulated cholesterol biosynthesis, a pro-inflammatory profile and reduced foam cell formation capacity

Insulin resistance is the central defining feature of type 2 diabetes and an independent risk factor for the development of atherosclerosis. In addition, aging is a major risk factor in the development of insulin resistance and cardiovascular disease. Macrophages play a pivotal roles the the developments of diabetes and atherosclerosis and express insulin receptors. Despite their relevance however, the effect of insulin and insulin resistance on macrophages regarding their inflammatory status, foam cell formation capacity and affect on atherosclerosis are unclear. By taking advantage of a mouse model that recapitulates the effects of chronic PI3K pathway hyperstimulation in macrophages through SHIP2 knock-down, we show that insulin resistance in aged macrophages promotes a proinflammatory phenotype while modulating the cholesterol biosynthesis pathway. These altered characteristics may contribute to the development of chronic inflammatory disease frequently observed with age. Moreover, aged insulin-resistant proinflammatory macrophages display an altered response to acute inflammatory stimulus and reduced foam cell formation capacity. Our work also highlights for the first time, the complex and contrasting immunomodulatory effects of insulin on macrophages in aged mice.\n\nSignificanceO_LIFirst study to explore the effects of macrophage insulin resistance in aged cells.\nC_LIO_LIInsulin resistance in aged macrophages results in the reprogramming of the transcriptome with more than 4000 genes being differentially regulated.\nC_LIO_LIInsulin resistance in aged macrophages results in upregulation of IFN signalling pathway, cholesterol biosynthesis pathway and inflammasome gene expression.\nC_LIO_LIInsulin directly regulates macrophage cholesterol biosynthesis, IFN and inflammasome gene expression in a time- and dose-dependent manner.\nC_LIO_LIInsulin resistant aged macrophages exhibit reduced capacity to become foam cells.\nC_LI

immunology↗

bioRxiv2018

Phosphorylation of LXRα impacts atherosclerosis regression by modulating monocyte/macrophage trafficking

LXR activation in macrophages enhances regression of atherosclerotic plaques in mice by regulating genes crucial for cholesterol efflux, cell motility and inflammation. Diabetes, however, impairs plaque regression in mice. LXR is phosphorylated at serine 198 (pS198), which affects the expression of genes controlling inflammation, lipid metabolism and cell movement. We hypothesize that LXR function is affected by hyperglycemia through changes in LXR pS198. Indeed, macrophages cultured in diabetes relevant high glucose versus normal glucose display alterations in LXR-dependent gene expression and increased LXR pS198. We therefore examined the consequence of disrupting LXR phosphorylation (S196A in mouse LXR) during regression of atherosclerosis in normal and diabetic mice. We find that phosphorylation deficient LXR S196A reduces macrophage retention in plaques in diabetes, which is predicted to be anti-atherogenic and enhance plaque regression. However, this favorable effect on regression is masked by increased monocyte infiltration in the plaque attributed to leukocytosis in LXR S196A mice. RNA-seq of plaque macrophages from diabetic S196A mice shows increased expression of chemotaxis and decreased expression of cell adhesion genes, consistent with reduced macrophage retention by LXR S196A. Thus, the non-phosphorylated form of LXR precludes macrophage retention in the plaque. Our study provides the first evidence for a physiological role of LXR phosphorylation in modulating atherosclerosis regression. Compounds that prevent LXR phosphorylation or ligands that induce the conformation of non-phosphorylated LXR may selectively enhance macrophage emigration from atherosclerotic plaques.

genetics↗

bioRxiv2017

Changes In LXRα Phosphorylation Promote A Novel Diet-Induced Transcriptome That Alters The Transition From Fatty Liver To Steatohepatitis

Understanding the transition from fatty liver or steatosis to more advanced inflammatory and fibrotic stages of non-alcoholic fatty liver disease (steatohepatitis), is key to define strategies that alter or even reverse the progression of this pathology. The Liver X Receptor alpha (LXR) controls hepatic lipid homeostasis and inflammation. Here we show that mice carrying a mutation that abolishes phosphorylation at Ser196 (S196A) in LXR exhibit reduced hepatic inflammation and fibrosis when challenged with a high fat-high cholesterol diet, despite displaying enhanced hepatic lipid accumulation. This protective effect is associated with reduced cholesterol accumulation, a key promoter of lipid-mediated hepatic damage. Reduced steatohepatitis in S196A mice involves the reprogramming of the liver transcriptome by promoting diet-induced changes in the expression of genes involved in endoplasmic reticulum stress, extracellular matrix remodelling, inflammation and lipid metabolism. Unexpectedly, changes in LXR phosphorylation uncover novel diet-specific target genes, whose regulation does not simply mirror ligand-induced LXR activation. These unique LXR phosphorylation-sensitive, diet-responsive target genes are revealed by promoting LXR occupancy and cofactor recruitment in the context of a cholesterol-rich diet. Therefore, LXR phosphorylation at Ser196 critically acts as a novel nutritional sensor that promotes a unique diet-induced transcriptome thereby modulating metabolic, inflammatory and fibrotic responses important in the transition to steatohepatitis.

pathology↗