Biology subjects

Liebisch, G.

Publications and source records attributed to Liebisch, G..

6 recordsLinked to original sources

bioRxiv2025

Mild weight loss promotes plaque growth and synthesis of pro-atherogenic lipids in ApoE-deficient mice fed a high-fat, high-cholesterol diet

BackgroundAccording to the recent ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease, achieving an initial weight loss of [≥]5% over six months in individuals with obesity is associated with clinically meaningful reductions in cardiovascular risk factors. However, emerging evidence suggests that weight loss may paradoxically increase the risk of CVD and atherosclerosis in certain populations. Motivated by these counterintuitive findings, we hypothesized that mild weight loss may induce metabolic reprogramming that promotes atherogenesis, potentially via an upregulation of pro-atherogenic lipids. MethodsApolipoprotein E-deficient mice were fed either a standard Chow or a high-cholesterol/high-fat (HCHF) diet for six months. A subset in each group underwent mild caloric restriction to achieve [~]5% body weight reduction. Atherosclerotic plaque burden in the brachiocephalic artery was assessed histologically. Hepatic lipidomic profiling was conducted via ESI-MS/MS, and lipid changes were compared with published plasma lipidomic data from obese human subjects stratified by CVD and diabetes status. Cardiovascular risk was further evaluated using the ceramide risk score (CERT1). ResultsMild weight loss induced significant plaque growth, increasing lesion area by 28% in Chow-fed and 53.8% in HCHF-fed mice relative to controls. In HCHF-fed mice, caloric restriction markedly elevated free cholesterol and multiple pro-atherogenic phospholipids, including nine phosphatidylcholine, six phosphatidylethanolamine, one lysophosphatidylcholine, two sphingomyelin, and three ceramide species. Seven cholesterol esters also increased, and a CERT1 score of 8.1 indicated high CVD risk. These pro-atherogenic lipids were confirmed by comparison with published plasma lipidomic data from CVD and diabetes patients. In contrast, weight loss under Chow conditions caused minimal lipid alterations, with only isolated increases in phosphatidylcholine and lysophosphatidylcholine species. ConclusionsMild weight loss under high-fat dietary conditions accelerates atherosclerosis through increased production of pro-atherogenic lipids. These findings underscore the need to monitor lipidomic responses during weight loss interventions in obese individuals with CVD risk. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=187 HEIGHT=200 SRC="FIGDIR/small/670993v1_ufig1.gif" ALT="Figure 1"> View larger version (71K): org.highwire.dtl.DTLVardef@1330150org.highwire.dtl.DTLVardef@19b2ee1org.highwire.dtl.DTLVardef@122c910org.highwire.dtl.DTLVardef@be7270_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical Abstract model of phospholipid-driven atherosclerosis progression. Graphical summary depicting the mechanistic link between hypercholesterolemia, phospholipid composition, and atherosclerotic plaque development. The left panel highlights pro-atherogenic phospholipids, while the right panel shows anti-atherogenic phospholipids, both grouped by class and correlated with plaque size. Phospholipids enclosed within the dashed box represent those exhibiting statistically significant changes. HighlightsO_LIMild weight loss ([~]5%) in ApoE-deficient mice fed a high-fat, high-cholesterol diet led to a paradoxical increase in atherosclerotic plaque burden. C_LIO_LIWeight loss under metabolically adverse dietary conditions may induce pro-atherogenic lipid remodelling that exacerbates atherosclerosis. C_LIO_LICareful monitoring of atherogenic lipid species may be warranted in obese patients with existing cardiovascular disease undergoing dietary interventions. C_LIO_LIComprehensive, tailored lifestyle interventions--beyond caloric restriction alone--may be necessary to avoid unintended cardiovascular harm during weight loss. C_LI

pathology↗

bioRxiv2025

Cholesteryl esters and high protein-to-lipid ratios distinguish Non-Vesicular Extracellular Particles from Extracellular Vesicles

Extracellular vesicles (EVs) are central to intercellular communication, yet the mechanisms underlying their biogenesis and diversity remain incompletely understood. Here, we integrate meta-analysis, advanced lipidomic, protein-to-lipid profiling, and super-resolution imaging to define the fundamental principles governing EV heterogeneity. Our meta-analysis of published transmission electron microcrographs across kingdoms reveals a highly conserved 110 nm average diameter and 200 nm upper size limit for intraluminal vesicles (ILVs), which are secreted as exosomes. Besides classical EV populations, we also characterize a distinct nanoparticle class: 167000 xg pellet of non-vesicular extracellular particles (167k-NVEPs), which exhibit a significantly higher protein-to-lipid ratio than 14000 xg pellet of large EVs (14k-lEVs) and 100000 xg pellet of small EVs (100k-sEVs), as measured by both biochemical assays and Raman spectroscopy. Lipid profiling demonstrates that 167k-NVEPs exhibit significant enrichment in cholesteryl esters and triacylglycerols, lipids typically associated with lipid droplets and the endosome/lysosome system. Analysis of lipid carbon-chain lengths reveals distinct signatures: 167k-NVEPs show pronounced enrichment at 16 and 18 carbons, while 100k-sEVs display enrichment at 32 and 34 carbons. This divergence indicates a potential connection to flexible biogenesis pathways. Marker heterogeneity across EV populations, confirmed by confocal and super-resolution microscopy, further underscores the limitations of relying on canonical tetraspanins for EV classification. Notably, 167k-NVEPs (likely exomeres) exhibit enrichment of Arf6 and CD63. Together, our findings provide compositional, biophysical, and molecular evidence supporting the formal recognition of 167k-NVEPs as a distinct class of extracellular particles and enabling exploring in disease biology and therapeutic delivery. Significance StatementExtracellular vesicles (EVs) are critical mediators of intercellular communication, yet their classification remains clouded by ambiguity in terms of their composition and biogenesis. This study resolves critical uncertainties through a cross-kingdom meta-analysis, establishing a conserved [~]110nm diameter and [~]200 nm upper size limit for intraluminal vesicles (ILVs), the precursors to exosomes. More significantly, we identify non-vesicular extracellular particles (167k-NVEPs) as a distinct class based on their unique sterol-rich lipidome, enrichment in lipids of 16 and 18 carbon chain length, elevated protein-to-lipid ratio, and functional cargo delivery. These features, alongside evidence of non-canonical origin and functional cargo delivery, establish NVEPs as a discrete class of extracellular particles.

cell biology↗

bioRxiv2023

ATF6 activation alters colonic lipid metabolism causing tumor-associated microbial adaptation

Endoplasmic reticulum unfolded protein responses (UPRER) contribute to cancer development and the activating transcription factor 6 (ATF6) is involved in microbiota-dependent tumorigenesis. Here, we substantiate the clinical relevance of ATF6 in early-onset and late colorectal cancer patient cohorts. Transcriptional analysis in intestinal epithelial cells (IEC) of ATF6 transgenic mice (nATF6IEC) identified bacteria-specific changes in cellular metabolism enriched for fatty acid biosynthesis. Untargeted metabolomics and isotype-labeling confirmed ATF6-related enrichment of long chain fatty acids in colonic tissue of patients, mice and organoid cultures. FASN inhibition and microbiota transfer in germ-free nATF6IEC mice confirmed the causal involvement of ATF6-induced lipid alterations in tumorigenesis. The selective expansion of tumor-relevant microbial taxa was mechanistically linked to long chain fatty acid exposure, using bioorthogonal non-canonical amino acid tagging (BONCAT) and growth analysis of Desulfovibrio isolates. We postulate chronic ATF6 signaling in the epithelium to select for tumor-promoting microbiota by altering lipid metabolism. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=126 SRC="FIGDIR/small/565267v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@be3756org.highwire.dtl.DTLVardef@231da4org.highwire.dtl.DTLVardef@16f3aaeorg.highwire.dtl.DTLVardef@1758fe3_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO Chronic ATF6 signaling in the colonic epithelium alters lipid metabolism to select a tumor-promoting microbiota C_FIG O_LIBiallelic expression of activated ATF6 (p50 nuclear fragment) in intestinal epithelial cells (nATF6IEC) induces spontaneous colon tumors in SPF but not GF mice C_LIO_LIMechanistically, biallelic SPF nATF6IEC mice alter colonic lipid metabolism, including the upregulation of LCFAs and Fasn C_LIO_LIInhibition of FASN prevents colon tumor formation in mice, and reduces the tumor-promoting potential of the intestinal microbiota (FMT) C_LIO_LIExposure of fl/fl control mouse microbiota to LCFAs ex vivo translationally activates tumor-associated bacteria, including Desulfovibrio fairfieldensis C_LIO_LIHuman CRC patients show ATF6 upregulation, FASN co-occurrence and increased LCFAs in T tissue C_LIO_LIATF6 activity links with CRC-associated microbiota in patients, including Desulfovibrio C_LI Created with BioRender.com nATF6: activated activating transcription factor 6; LCFA: long-chain fatty acids; SAFA: saturated fatty acids; Fasn: fatty acid synthase; C75 i.p.: intraperitoneal injection of the Fasn inhibitor C75.

cancer biology↗

bioRxiv2023

Secondary bile acid production by gut bacteria promotes Western diet-associated colorectal cancer

Western diet is an important risk factor for the development of sporadic colorectal cancer (CRC). Dietary fat stimulates bile acid (BA) production by the host and their conversion to secondary BAs by 7-dehydroxylating (7DH+) bacteria, but causal proof of their tumor-promoting effects in vivo is lacking. To address this, we performed feeding studies in a genetically engineered pig model of CRC combined with multi-omics analyses and gnotobiotic mouse studies. Western diet worsened the disease phenotype in APC1311/+ pigs. This was accompanied by microbiota changes, increased levels of the secondary bile acid deoxycholic acid (DCA), and higher colonic epithelial cell proliferation. The latter was counteracted by using the BA-scavenging drug colestyramine. Metagenomic analysis across multiple cohorts revealed higher occurrence of bai (BA inducible) operons from Clostridium scindens and close relatives in stool of CRC subjects (n = 1,034). Using two gnotobiotic mouse models of CRC, we demonstrate that colonization with 7DH+ bacteria (C. scindens or Extibacter muris) increased colonic tumor loads. This work provides clear evidence for the causal role of microbiome-derived DCA production in CRC under detrimental dietary conditions, opening avenues for future preventive strategies.

microbiology↗

bioRxiv2022

The gut microbiota promotes liver regeneration through hepatic membrane phospholipid synthesis

Background & AimsHepatocyte growth and proliferation is dependent on the synthesis of membrane phospholipids. Lipid synthesis, in turn, requires short chain fatty acids (SCFA) generated by bacterial fermentation, delivered through the gut- liver axis. We therefore hypothesized that dysbiotic insults like antibiotics treatment not only negatively affect gut microbiota, but also impair hepatic lipid synthesis and liver regeneration. MethodsStable isotope labelling and 70% partial hepatectomy (PHx) was carried out in C57Bl/6J wildtype mice, in mice treated with broad-spectrum antibiotics, in germfree mice and gnotobiotic mice colonized with minimal microbiota. Microbiome was analysed by 16S rRNA gene sequencing and microbial culture. Gut content, liver and blood were tested by lipidomics mass spectrometry, qRT-PCR, immunoblot and immunohistochemistry for expression of proliferative and lipogenic markers. Matched biopsies from hyperplastic and hypoplastic liver tissue of human patients subjected to portal vein embolization were analysed by qRT-PCR for lipogenic enzymes and results were correlated with liver volumetry. ResultsThree days of antibiotics treatment induced persistent dysbiosis with significantly decreased beta-diversity and richness, but massive increase of Proteobacteria, accompanied by decreased colonic SCFA. After PHx, antibiotics- treated mice showed delayed liver regeneration, increased mortality, impaired hepatocyte proliferation and decreased hepatic phospholipid synthesis. Expression of the key lipogenic enzyme SCD1 was upregulated after PHx, but delayed by antibiotics-treatment. Germfree mice essentially recapitulated the phenotype of antibiotics-treatment. Importantly, phospholipid synthesis, hepatocyte proliferation, liver regeneration and survival were rescued in gnotobiotic mice colonized with a minimal SCFA-producing microbial community. SCD1 was required for human hepatoma cell proliferation, and its hepatic expression was associated with liver regeneration and hyperproliferation in human patients. ConclusionGut microbiota are pivotal for hepatic membrane phospholipid synthesis and liver regeneration. Lay SummaryGut microbiota affects the liver lipid metabolism through the gut-liver axis, and microbial metabolites promote liver regeneration. Perturbations of the microbiome, e.g., by antibiotics treatment, impair the production of bacterial metabolites, which serve as building blocks for new membrane lipids in liver cells. As a consequence, hepatocyte growth and proliferation, and ultimately, liver regeneration and survival after liver surgery is impaired. HighlightsO_LIPartial hepatectomy in mice pretreated with antibiotics is associated with impaired hepatocyte proliferation and phospholipid synthesis, delayed liver regeneration and increased mortality C_LIO_LIThe delay in liver regeneration and impaired lipogenesis upon antibiotics treatment is preceded by dysbiosis of gut microbiota, increase of Proteobacteria and decreased short-chain fatty acids in the gut C_LIO_LIPartial hepatectomy in germfree mice essentially phenocopies the detrimental effects of antibiotic treatment C_LIO_LILiver regeneration and mortality, as well as phospholipid synthesis and hepatocyte proliferation in germfree mice are fully rescued upon colonisation with a minimal gut bacterial consortium capable of short-chain fatty acid production C_LIO_LIIn human patients, the intrahepatic expression of lipid synthesis enzymes positively correlates with proliferation and liver regeneration in the clinic C_LIO_LIThus, liver regeneration is affected by composition of gut microbiota C_LIO_LIClinically, pre-operative analysis of the gut microbiome may serve as biomarker to determine the extent of liver resections C_LI

cell biology↗

bioRxiv2020

Human adipocyte differentiation and composition of disease relevant lipids are regulated by miR-221-3p

MicroRNA-221-3p (miR-221-3p) is associated with both metabolic diseases and cancers. However, its role in terminal adipocyte differentiation, adipocyte lipid metabolism, and lipid signaling in human disease are uncharacterized. miR-221-3p or its inhibitor were transfected into differentiating or mature human adipocytes. Triglyceride (TG) content and adipogenic gene expression were monitored, global lipidome analysis was carried out, and mechanisms underlying the effects of miR-221-3p were investigated. Finally, cross-talk between miR-221-3p expressing adipocytes and MCF-7 breast carcinoma (BC) cells was studied, and miR-221-3p expression in tumor-proximal adipose biopsies from BC patients analyzed. miR-221-3p overexpression inhibited terminal differentiation of adipocytes, as judged from reduced TG storage and gene expression of the adipogenic markers SCD1, GLUT4, FAS, DGAT1/2, AP2, ATGL and AdipoQ. The signaling adaptor protein 14-3-3γ was identified as a potential mediator of the miR-221-3p effects. Importantly, miR-221-3p overexpression inhibited de novo lipogenesis but increased the concentrations of ceramides and sphingomyelins, while reducing diacylglycerols, concomitant with suppression of sphingomyelin phosphodiesterase, ATP citrate lyase, and acid ceramidase. miR-221-3p expression was elevated in tumor proximal adipose tissue from patients with invasive BC. Conditioned medium of miR-221-3p overexpressing adipocytes stimulated the invasion and proliferation of BC cells, while medium of the BC cells enhanced miR-221-3p expression in adipocytes. miR-221-3p plays a pivotal role in the terminal differentiation of white adipocytes and their lipid composition. Elevated miR-221-3p impairs adipocyte lipid storage and differentiation, and modifies their ceramide, sphingomyelin, and diacylglycerol content. These alterations are relevant for metabolic diseases but may also affect cancer progression.View Full Text

cell biology↗