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1.
PLoS One ; 19(5): e0302485, 2024.
Article En | MEDLINE | ID: mdl-38691537

BACKGROUND: The etiology of diabetic kidney disease is complex, and the role of lipoproteins and their lipid components in the development of the disease cannot be ignored. However, phospholipids are an essential component, and no Mendelian randomization studies have yet been conducted to examine potential causal associations between phospholipids and diabetic kidney disease. METHODS: Relevant exposure and outcome datasets were obtained through the GWAS public database. The exposure datasets included various phospholipids, including those in LDL, IDL, VLDL, and HDL. IVW methods were the primary analytical approach. The accuracy of the results was validated by conducting heterogeneity, MR pleiotropy, and F-statistic tests. MR-PRESSO analysis was utilized to identify and exclude outliers. RESULTS: Phospholipids in intermediate-density lipoprotein (OR: 0.8439; 95% CI: 0.7268-0.9798), phospholipids in large low- density lipoprotein (OR: 0.7913; 95% CI: 0.6703-0.9341), phospholipids in low- density lipoprotein (after removing outliers, OR: 0.788; 95% CI: 0.6698-0.9271), phospholipids in medium low- density lipoprotein (OR: 0.7682; 95% CI: 0.634-0.931), and phospholipids in small low-density lipoprotein (after removing outliers, OR: 0.8044; 95% CI: 0.6952-0.9309) were found to be protective factors. CONCLUSIONS: This study found that a higher proportion of phospholipids in intermediate-density lipoprotein and the various subfractions of low-density lipoprotein, including large LDL, medium LDL, and small LDL, is associated with a lower risk of developing diabetic kidney disease.


Diabetic Nephropathies , Mendelian Randomization Analysis , Phospholipids , Humans , Diabetic Nephropathies/genetics , Diabetic Nephropathies/metabolism , Phospholipids/metabolism , Genome-Wide Association Study , Lipoproteins/blood , Lipoproteins/genetics , Lipoproteins/metabolism , Lipoproteins, LDL/blood , Polymorphism, Single Nucleotide
2.
Front Cell Infect Microbiol ; 14: 1362765, 2024.
Article En | MEDLINE | ID: mdl-38562963

Cestodes use own lipid-binding proteins to capture and transport hydrophobic ligands, including lipids that they cannot synthesise as fatty acids and cholesterol. In E. granulosus s.l., one of these lipoproteins is antigen B (EgAgB), codified by a multigenic and polymorphic family that gives rise to five gene products (EgAgB8/1-5 subunits) assembled as a 230 kDa macromolecule. EgAgB has a diagnostic value for cystic echinococcosis, but its putative role in the immunobiology of this infection is still poorly understood. Accumulating research suggests that EgAgB has immunomodulatory properties, but previous studies employed denatured antigen preparations that might exert different effects than the native form, thereby limiting data interpretation. This work analysed the modulatory actions on macrophages of native EgAgB (nEgAgB) and the recombinant form of EgAg8/1, which is the most abundant subunit in the larva and was expressed in insect S2 cells (rEgAgB8/1). Both EgAgB preparations were purified to homogeneity by immunoaffinity chromatography using a novel nanobody anti-EgAgB8/1. nEgAgB and rEgAgB8/1 exhibited differences in size and lipid composition. The rEgAgB8/1 generates mildly larger lipoproteins with a less diverse lipid composition than nEgAgB. Assays using human and murine macrophages showed that both nEgAgB and rEgAgB8/1 interfered with in vitro LPS-driven macrophage activation, decreasing cytokine (IL-1ß, IL-6, IL-12p40, IFN-ß) secretion and ·NO generation. Furthermore, nEgAgB and rEgAgB8/1 modulated in vivo LPS-induced cytokine production (IL-6, IL-10) and activation of large (measured as MHC-II level) and small (measured as CD86 and CD40 levels) macrophages in the peritoneum, although rEgAgB8/1 effects were less robust. Overall, this work reinforced the notion that EgAgB is an immunomodulatory component of E. granulosus s.l. Although nEgAgB lipid's effects cannot be ruled out, our data suggest that the EgAgB8/1 subunit contributes to EgAgB´s ability to regulate the inflammatory activation of macrophages.


Echinococcus granulosus , Humans , Animals , Mice , Echinococcus granulosus/genetics , Echinococcus granulosus/metabolism , Interleukin-6/metabolism , Lipopolysaccharides/metabolism , Macrophage Activation , Lipoproteins/genetics , Lipoproteins/metabolism , Macrophages , Cytokines/metabolism
3.
Sci Rep ; 14(1): 8502, 2024 04 12.
Article En | MEDLINE | ID: mdl-38605235

The current state of knowledge on the relationship between lifestyle factors, glycemic traits, lipoprotein traits with liver cancer risk is still uncertain despite some attempts made by observational studies. This study aims to investigate the causal genetic relationship between factors highly associated with liver cancer incidence by using Mendelian randomization (MR) analysis. Employing MR analysis, this study utilized previously published GWAS datasets to investigate whether lifestyle factors, glycemic traits, and lipoprotein traits would affect the risk of liver cancer. The study utilized three MR methods, including inverse variance-weighted model (IVW), MR Egger, and weighted median. Furthermore, MR-Egger analyses were performed to detect heterogeneity in the MR results. The study also conducted a leave-one-out analysis to assess the potential influence of individual SNPs on the MR analysis results. MR-PRESSO was used to identify and remove SNP outliers associated with liver cancer. MR analyses revealed that 2-h glucose (odds ratio, OR 2.33, 95% confidence interval, CI 1.28-4.21), type 2 diabetes mellitus (T2DM, OR 1.67, 95% CI 1.18-2.37), body mass index (BMI, OR 1.67, 95% CI 1.18-2.37), waist circumference (OR 1.78, 95% CI 1.18-2.37) were associated with increased risk of liver cancer. On the contrary, apolipoproteins B (APOB, OR 0.67, 95% CI 0.47-0.97), and low-density lipoprotein (LDL, OR 0.62, 95% CI 0.42-0.92) were negatively related to liver cancer risk. Additionally, after adjusting for BMI, apolipoproteins A-I (APOA-I, OR 0.56, 95% CI, 0.38-0.81), total cholesterol (TC, OR 0.72, 95% CI, 0.54-0.94), and total triglycerides (TG, OR 0.57, 95% CI, 0.40-0.78) exhibited a significant inverse correlation with the risk of liver cancer. This study supports a causal relationship between 2-h glucose, T2DM, BMI, and waist circumference with the increased risk of liver cancer. Conversely, the study reveals a cause-effect relationship between TC, TG, LDL, APOA-I, and APOB with a decreased risk of liver cancer.


Diabetes Mellitus, Type 2 , Liver Neoplasms , Humans , Apolipoprotein A-I/genetics , Mendelian Randomization Analysis , Lipoproteins/genetics , Liver Neoplasms/epidemiology , Liver Neoplasms/genetics , Apolipoproteins B/genetics , Glucose , Genome-Wide Association Study , Risk Factors
4.
Infect Immun ; 92(5): e0044723, 2024 May 07.
Article En | MEDLINE | ID: mdl-38629841

Streptococcus pneumoniae, a common colonizer of the upper respiratory tract, invades nasopharyngeal epithelial cells without causing disease in healthy participants of controlled human infection studies. We hypothesized that surface expression of pneumococcal lipoproteins, recognized by the innate immune receptor TLR2, mediates epithelial microinvasion. Mutation of lgt in serotype 4 (TIGR4) and serotype 6B (BHN418) pneumococcal strains abolishes the ability of the mutants to activate TLR2 signaling. Loss of lgt also led to the concomitant decrease in interferon signaling triggered by the bacterium. However, only BHN418 lgt::cm but not TIGR4 lgt::cm was significantly attenuated in epithelial adherence and microinvasion compared to their respective wild-type strains. To test the hypothesis that differential lipoprotein repertoires in TIGR4 and BHN418 lead to the intraspecies variation in epithelial microinvasion, we employed a motif-based genome analysis and identified an additional 525 a.a. lipoprotein (pneumococcal accessory lipoprotein A; palA) encoded by BHN418 that is absent in TIGR4. The gene encoding palA sits within a putative genetic island present in ~10% of global pneumococcal isolates. While palA was enriched in the carriage and otitis media pneumococcal strains, neither mutation nor overexpression of the gene encoding this lipoprotein significantly changed microinvasion patterns. In conclusion, mutation of lgt attenuates epithelial inflammatory responses during pneumococcal-epithelial interactions, with intraspecies variation in the effect on microinvasion. Differential lipoprotein repertoires encoded by the different strains do not explain these differences in microinvasion. Rather, we postulate that post-translational modifications of lipoproteins may account for the differences in microinvasion.IMPORTANCEStreptococcus pneumoniae (pneumococcus) is an important mucosal pathogen, estimated to cause over 500,000 deaths annually. Nasopharyngeal colonization is considered a necessary prerequisite for disease, yet many people are transiently and asymptomatically colonized by pneumococci without becoming unwell. It is therefore important to better understand how the colonization process is controlled at the epithelial surface. Controlled human infection studies revealed the presence of pneumococci within the epithelium of healthy volunteers (microinvasion). In this study, we focused on the regulation of epithelial microinvasion by pneumococcal lipoproteins. We found that pneumococcal lipoproteins induce epithelial inflammation but that differing lipoprotein repertoires do not significantly impact the magnitude of microinvasion. Targeting mucosal innate immunity and epithelial microinvasion alongside the induction of an adaptive immune response may be effective in preventing pneumococcal colonization and disease.


Epithelial Cells , Lipoproteins , Pneumococcal Infections , Streptococcus pneumoniae , Streptococcus pneumoniae/immunology , Streptococcus pneumoniae/genetics , Streptococcus pneumoniae/pathogenicity , Humans , Lipoproteins/genetics , Lipoproteins/metabolism , Lipoproteins/immunology , Epithelial Cells/microbiology , Epithelial Cells/immunology , Pneumococcal Infections/immunology , Pneumococcal Infections/microbiology , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Toll-Like Receptor 2/metabolism , Toll-Like Receptor 2/genetics , Toll-Like Receptor 2/immunology , Nasopharynx/microbiology , Mutation , Bacterial Adhesion
5.
Nature ; 628(8006): 130-138, 2024 Apr.
Article En | MEDLINE | ID: mdl-38448586

Genome-wide association analyses using high-throughput metabolomics platforms have led to novel insights into the biology of human metabolism1-7. This detailed knowledge of the genetic determinants of systemic metabolism has been pivotal for uncovering how genetic pathways influence biological mechanisms and complex diseases8-11. Here we present a genome-wide association study for 233 circulating metabolic traits quantified by nuclear magnetic resonance spectroscopy in up to 136,016 participants from 33 cohorts. We identify more than 400 independent loci and assign probable causal genes at two-thirds of these using manual curation of plausible biological candidates. We highlight the importance of sample and participant characteristics that can have significant effects on genetic associations. We use detailed metabolic profiling of lipoprotein- and lipid-associated variants to better characterize how known lipid loci and novel loci affect lipoprotein metabolism at a granular level. We demonstrate the translational utility of comprehensively phenotyped molecular data, characterizing the metabolic associations of intrahepatic cholestasis of pregnancy. Finally, we observe substantial genetic pleiotropy for multiple metabolic pathways and illustrate the importance of careful instrument selection in Mendelian randomization analysis, revealing a putative causal relationship between acetone and hypertension. Our publicly available results provide a foundational resource for the community to examine the role of metabolism across diverse diseases.


Biomarkers , Genome-Wide Association Study , Metabolomics , Female , Humans , Pregnancy , Acetone/blood , Acetone/metabolism , Biomarkers/blood , Biomarkers/metabolism , Cholestasis, Intrahepatic/blood , Cholestasis, Intrahepatic/genetics , Cholestasis, Intrahepatic/metabolism , Cohort Studies , Genome-Wide Association Study/methods , Hypertension/blood , Hypertension/genetics , Hypertension/metabolism , Lipoproteins/genetics , Lipoproteins/metabolism , Magnetic Resonance Spectroscopy , Mendelian Randomization Analysis , Metabolic Networks and Pathways/genetics , Phenotype , Polymorphism, Single Nucleotide/genetics , Pregnancy Complications/blood , Pregnancy Complications/genetics , Pregnancy Complications/metabolism
6.
Lipids Health Dis ; 23(1): 83, 2024 Mar 20.
Article En | MEDLINE | ID: mdl-38509578

OBJECTIVE: To enhance the detection, management and monitoring of Chinese children afflicted with sitosterolemia by examining the physical characteristics and genetic makeup of pediatric patients. METHODS: In this group, 26 children were diagnosed with sitosterolemia, 24 of whom underwent genetic analysis. Patient family medical history, physical symptoms, tests for liver function, lipid levels, standard blood tests, phytosterol levels, cardiac/carotid artery ultrasounds, fundus examinations, and treatment were collected. RESULTS: The majority (19, 73.1%) of the 26 patients exhibited xanthomas as the most prevalent manifestation. The second most common symptoms were joint pain (7, 26.9%) and stunted growth (4, 15.4%). Among the 24 (92.3%) patients whose genetics were analyzed, 16 (66.7%) harbored ABCG5 variants (type 2 sitosterolemia), and nearly one-third (8, 33.3%) harbored ABCG8 variants (type 1 sitosterolemia). Additionally, the most common pathogenic ABCG5 variant was c.1166G > A (p.Arg389His), which was found in 10 patients (66.7%). Further analysis did not indicate any significant differences in pathological traits among those carrying ABCG5 and ABCG8 variations (P > 0.05). Interestingly, there was a greater abundance of nonsense variations in ABCG5 than in ABCG8 (P = 0.09), and a greater frequency of splicing variations in ABCG8 than ABCG5 (P = 0.01). Following a change in diet or a combination of ezetimibe, the levels of cholesterol and low-density lipoprotein were markedly decreased compared to the levels reported before treatment. CONCLUSION: Sitosterolemia should be considered for individuals presenting with xanthomas and increased cholesterol levels. Phytosterol testing and genetic analysis are important for early detection. Managing one's diet and taking ezetimibe can well control blood lipids.


Hypercholesterolemia , Intestinal Diseases , Lipid Metabolism, Inborn Errors , Phytosterols , Phytosterols/adverse effects , Xanthomatosis , Humans , Child , Lipoproteins/genetics , ATP Binding Cassette Transporter, Subfamily G, Member 5/genetics , Phytosterols/genetics , Cholesterol , Ezetimibe/therapeutic use
7.
Microbiol Immunol ; 68(4): 155-159, 2024 Apr.
Article En | MEDLINE | ID: mdl-38311883

Streptococcus pneumoniae is a causative agent of community-acquired pneumonia. Upon pneumococcal infection, innate immune cells recognize pneumococcal lipoproteins via Toll-like receptor 2 and induce inflammation. Here, we generated a strain of S. pneumoniae deficient in lipoprotein signal peptidase (LspA), a transmembrane type II signal peptidase required for lipoprotein maturation, to investigate the host immune response against this strain. Triton X-114 phase separation revealed that lipoprotein expression was lower in the LspA-deficient strain than in the wild-type strain. Additionally, the LspA-deficient strain decreased nuclear factor-κB activation and cytokine production in THP-1 cells, indicating impaired innate immune response against the strain.


Aspartic Acid Endopeptidases , Streptococcus pneumoniae , Toll-Like Receptor 2 , Animals , Mice , Streptococcus pneumoniae/genetics , Toll-Like Receptor 2/genetics , Toll-Like Receptor 2/metabolism , Bacterial Proteins/metabolism , Lipoproteins/genetics , Lipoproteins/metabolism , Mice, Inbred C57BL
8.
Hum Genomics ; 18(1): 19, 2024 Feb 12.
Article En | MEDLINE | ID: mdl-38347599

The causal relationships between plasma metabolites and cholelithiasis/cholecystitis risks remain elusive. Using two-sample Mendelian randomization, we found that genetic proxied plasma campesterol level showed negative correlation with the risk of both cholelithiasis and cholecystitis. Furthermore, the increased risk of cholelithiasis is correlating with the increased level of plasma campesterol. Lastly, genetic colocalization study showed that the leading SNP, rs4299376, which residing at the ABCG5/ABCG8 gene loci, was shared by plasma campesterol level and cholelithiasis, indicating that the aberrant transportation of plant sterol/cholesterol from the blood stream to the bile duct/gut lumen might be the key in preventing cholesterol gallstone formation.


Cholecystitis , Cholesterol/analogs & derivatives , Gallstones , Phytosterols , Humans , Lipoproteins/genetics , Mendelian Randomization Analysis , ATP Binding Cassette Transporter, Subfamily G, Member 8/genetics , ATP Binding Cassette Transporter, Subfamily G, Member 5/genetics , Cholecystitis/epidemiology , Cholecystitis/genetics , Gallstones/epidemiology , Gallstones/genetics , Gallstones/metabolism
9.
Curr Opin Clin Nutr Metab Care ; 27(2): 125-135, 2024 Mar 01.
Article En | MEDLINE | ID: mdl-38320159

PURPOSE OF REVIEW: Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death despite the development of effective treatments. Recently, elevated remnant cholesterol and low-grade inflammation have emerged as factors explaining part of the residual ASCVD risk. Interestingly, the coexistence of both high remnant cholesterol and low-grade inflammation can further increase the risk of ASCVD. The aim of this review is to describe the role of elevated remnant cholesterol and low-grade inflammation, separately and combined, in ASCVD. RECENT FINDINGS: Results from recently published studies, including observational and genetic Mendelian randomization studies, support a causal relationship between elevated remnant cholesterol and low-grade inflammation on risk of ASCVD in both primary and secondary prevention settings. In addition, current evidence from observational studies suggests that the coexistence of elevated remnant cholesterol and low-grade inflammation further increases the risk of ASCVD. SUMMARY: Recent observational studies suggest that high remnant cholesterol combined with low-grade inflammation may confer a particular high risk for ASCVD. Attention on the dual threat from high remnant cholesterol and low-grade inflammation is necessary, and further research in this field is warranted. The effect of remnant cholesterol-lowering drugs and anti-inflammatory drugs on ASCVD risk alone and combined remains to be elucidated. VIDEO ABSTRACT: http://links.lww.com/COCN/A20.


Atherosclerosis , Cardiovascular Diseases , Humans , Triglycerides , Cardiovascular Diseases/etiology , Lipoproteins/genetics , Cholesterol , Atherosclerosis/etiology , Inflammation/complications , Risk Factors
10.
PLoS Biol ; 22(1): e3002451, 2024 Jan.
Article En | MEDLINE | ID: mdl-38180978

Lipoproteins of the opportunistic pathogen Staphylococcus aureus play a crucial role in various cellular processes and host interactions. Consisting of a protein and a lipid moiety, they support nutrient acquisition and anchor the protein to the bacterial membrane. Recently, we identified several processed and secreted small linear peptides that derive from the secretion signal sequence of S. aureus lipoproteins. Here, we show, for the first time, that the protein moiety of the S. aureus lipoprotein CamS has a biological role that is distinct from its associated linear peptide staph-cAM373. The small peptide was shown to be involved in interspecies horizontal gene transfer, the primary mechanism for the dissemination of antibiotic resistance among bacteria. We provide evidence that the CamS protein moiety is a potent repressor of cytotoxins, such as α-toxin and leukocidins. The CamS-mediated suppression of toxin transcription was reflected by altered disease severity in in vivo infection models involving skin and soft tissue, as well as bloodstream infections. Collectively, we have uncovered the role of the protein moiety of the staphylococcal lipoprotein CamS as a previously uncharacterized repressor of S. aureus toxin production, which consequently regulates virulence and disease outcomes. Notably, the camS gene is conserved in S. aureus, and we also demonstrated the muted transcriptional response of cytotoxins in 2 different S. aureus lineages. Our findings provide the first evidence of distinct biological functions of the protein moiety and its associated linear peptide for a specific lipoprotein. Therefore, lipoproteins in S. aureus consist of 3 functional components: a lipid moiety, a protein moiety, and a small linear peptide, with putative different biological roles that might not only determine the outcome of host-pathogen interactions but also drive the acquisition of antibiotic resistance determinants.


Staphylococcal Infections , Staphylococcus aureus , Humans , Staphylococcus aureus/genetics , Lipoproteins/genetics , Host-Pathogen Interactions , Cell Adhesion Molecules , Cytotoxins , Peptides
11.
EBioMedicine ; 100: 104964, 2024 Feb.
Article En | MEDLINE | ID: mdl-38181703

BACKGROUND: Quantitative nuclear magnetic resonance (NMR) metabolomics techniques provide detailed measurements of lipoprotein particle concentration. Metabolic dysfunction often represents a cluster of conditions, including dyslipidaemia, hypertension, and diabetes, that increase the risk of cardiovascular diseases (CVDs). However, the causal relationship between lipid profiles and blood pressure (BP) remains unclear. We performed a Mendelian Randomisation (MR) study to disentangle and prioritize the potential causal effects of major lipids, lipoprotein particles, and circulating metabolites on BP and pulse pressure (PP). METHODS: We employed single-nucleotide polymorphisms (SNPs) associated with major lipids, lipoprotein particles, and other metabolites from the UK Biobank as instrumental variables. Summary-level data for BP and PP were obtained from the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort. Two-sample MR and MR Bayesian model averaging approaches (MR-BMA) were conducted to analyse and rank causal associations. FINDINGS: Genetically predicted TG was the most likely causal exposure among the major lipids to increase systolic blood pressure (SBP) and diastolic blood pressure (DBP), with marginal inclusion probabilities (MIPs) of 0.993 and 0.847, respectively. Among the majority of lipoproteins and their containing lipids, including major lipids, genetically elevated TG in small high-density lipoproteins (S_HDL_TG) had the strongest association with the increase of SBP and DBP, with MIPs of 0.416 and 0.397, respectively. HDL cholesterol (HDL_C) and low-density lipoprotein cholesterol (LDL_C) were potential causal factors for PP elevation among the major lipids (MIP = 0.927 for HDL_C and MIP = 0.718 for LDL_C). Within the sub-lipoproteins, genetically predicted atherogenic lipoprotein particles (i.e., sub-very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and LDL particles) had the most likely causal impact on increasing PP. INTERPRETATION: This study provides genetic evidence for the causality of lipids on BP indicators. However, the effect size on SBP, DBP, and PP varies depending on the lipids' components and sizes. Understanding this potential relationship may inform the potential benefits of comprehensive management of lipid profiles for BP control. FUNDING: Key Research and Development Program of Hubei Province, Science and Technology Innovation Project of Huanggang Central Hospital of Yangtze University, the Hubei Industrial Technology Research Institute of Heart-Brain Diseases, and the Hubei Provincial Engineering Research Centre of Comprehensive Care for Heart-Brain Diseases.


Brain Diseases , Lipoproteins , Adult , Humans , Blood Pressure/genetics , Triglycerides , Bayes Theorem , Lipoproteins/genetics , Cholesterol, LDL , Cholesterol, HDL , Mendelian Randomization Analysis , Risk Factors
12.
mBio ; 15(2): e0303923, 2024 Feb 14.
Article En | MEDLINE | ID: mdl-38193657

The outer membrane (OM) is an essential organelle of Gram-negative bacteria. Lipoproteins are key to building the OM, performing essential functions in several OM assembly machines. Lipoproteins mature in the inner membrane (IM) and are then trafficked to the OM. In Escherichia coli, the LolCDE transporter is needed to extract lipoproteins from the IM to begin trafficking. Lipoproteins are then transferred from LolCDE to the periplasmic chaperone LolA which ferries them to the OM for insertion by LolB. LolA recruitment by LolC is an essential trafficking step. Structural and biochemical studies suggested that two regions (termed Hook and Pad) within a periplasmic loop of LolC worked in tandem to recruit LolA, leading to a bipartite model for recruitment. Here, we genetically examine the LolC periplasmic loop in vivo using E. coli. Our findings challenge the bipartite interaction model. We show that while the Hook is essential for lipoprotein trafficking in vivo, lipoproteins are still efficiently trafficked when the Pad residues are inactivated. We show with AlphaFold2 multimer modeling that Hook:LolA interactions are likely universal among diverse Gram-negative bacteria. Conversely, Pad:LolA interactions vary across phyla. Our in vivo data redefine LolC:LolA recruitment into a hierarchical interaction model. We propose that the Hook is the major player in LolA recruitment, while the Pad plays an ancillary role that is important for efficiency but is ultimately dispensable. Our findings expand the understanding of a fundamental step in essential lipoprotein trafficking and have implications for efforts to develop new antibacterials that target LolCDE.IMPORTANCEResistance to current antibiotics is increasingly common. New antibiotics that target essential processes are needed to expand clinical options. For Gram-negative bacteria, their cell surface-the outer membrane (OM)-is an essential organelle and antibiotic barrier that is an attractive target for new antibacterials. Lipoproteins are key to building the OM. The LolCDE transporter is needed to supply the OM with lipoproteins and has been a focus of recent antibiotic discovery. In vitro evidence recently proposed a two-part interaction of LolC with LolA lipoprotein chaperone (which traffics lipoproteins to the OM) via "Hook" and "Pad" regions. We show that this model does not reflect lipoprotein trafficking in vivo. Only the Hook is essential for lipoprotein trafficking and is remarkably robust to mutational changes. The Pad is non-essential for lipoprotein trafficking but plays an ancillary role, contributing to trafficking efficiency. These insights inform ongoing efforts to drug LolCDE.


Escherichia coli Proteins , Periplasmic Binding Proteins , Escherichia coli/genetics , Escherichia coli/metabolism , Escherichia coli Proteins/metabolism , Molecular Chaperones/genetics , Molecular Chaperones/metabolism , Lipoproteins/genetics , Lipoproteins/metabolism , Membrane Transport Proteins/metabolism , Gram-Negative Bacteria/metabolism , Anti-Bacterial Agents/metabolism , Bacterial Outer Membrane Proteins/genetics , Bacterial Outer Membrane Proteins/metabolism , Periplasmic Binding Proteins/genetics , Periplasmic Binding Proteins/metabolism
13.
mSystems ; 9(1): e0108723, 2024 Jan 23.
Article En | MEDLINE | ID: mdl-38078774

Borrelia burgdorferi, the pathogen of Lyme disease, differentially produces many outer surface proteins (Osp), some of which represent the most abundant membrane proteins, such as OspA, OspB, and OspC. In cultured bacteria, these proteins can account for a substantial fraction of the total cellular or membrane proteins, posing challenges to the identification and analysis of non-abundant proteins, which could serve as novel pathogen detection markers or as vaccine candidates. Herein, we introduced serial mutations to remove these abundant Osps and generated a B. burgdorferi mutant deficient in OspA, OspB, and OspC in an infectious 297-isolate background, designated as OspABC- mutant. Compared to parental isolate, the mutant did not reflect growth defects in the cultured medium but showed differential mRNA expression of representative tested genes, in addition to gross changes in cellular and membrane protein profiles. The analysis of differentially detectable protein contents of the OspABC- mutant, as compared to the wild type, by two-dimensional gel electrophoresis followed by liquid chromatography-mass spectrometry, identified several spirochete proteins that are dominated by proteins of unknown functions, as well as membrane transporters, chaperons, and metabolic enzymes. We produced recombinant forms of two of these represented proteins, BBA34 and BB0238, and showed that these proteins are detectable during spirochete infection in the tick-borne murine model of Lyme borreliosis and thus serve as potential antigenic markers of the infection.IMPORTANCEThe present manuscript employed a systemic approach to identify non-abundant proteins in cultured Borrelia burgdorferi that are otherwise masked or hidden due to the overwhelming presence of abundant Osps like OspA, OspB, and OspC. As these Osps are either absent or transiently expressed in mammals, we performed a proof-of-concept study in which their removal allowed the analysis of otherwise less abundant antigens in OspABC-deficient mutants and identified several immunogenic proteins, including BBA34 and BB0238. These antigens could serve as novel vaccine candidates and/or genetic markers of Lyme borreliosis, promoting new research in the clinical diagnosis and prevention of Lyme disease.


Borrelia burgdorferi , Lyme Disease , Mice , Animals , Antigens, Bacterial/genetics , Bacterial Outer Membrane Proteins/genetics , Lipoproteins/genetics , Bacterial Vaccines/genetics , Antigens, Surface/genetics , Lyme Disease/diagnosis , Borrelia burgdorferi/genetics , Mammals
14.
J Orthop Res ; 42(5): 1033-1044, 2024 May.
Article En | MEDLINE | ID: mdl-38044472

High fat diets overwhelm the physiological mechanisms for absorption, storage, and utilization of triglycerides (TG); consequently TG, TG-rich lipoproteins (TGRL), and TGRL remnants accumulate, circulate systemically, producing dyslipidemia. This associates with, or is causative for increased atherosclerotic cardiovascular risk, ischemic stroke, fatty liver disease, and pancreatitis. TGRL hydrolysis by endothelial surface-bound lipoprotein lipase (LPL) generates metabolites like free fatty acids which have proinflammatory properties. While osteoblasts utilize fatty acids as an energy source, dyslipidemia is associated with negative effects on the skeleton. In this study we investigated the effects of TGRL lipolysis products (TGRL-LP) on expression of a stress responsive transcription factor, termed activating transcription factor 3 (ATF3), reactive oxygen species (ROS), ATF3 target genes, and angiopoietin-like 4 (Angptl4) in osteoblasts. As ATF3 negatively associates with osteoblast differentiation, we also investigated the skeletal effects of global ATF3 deletion in mice. TGRL-LP increased expression of Atf3, proinflammatory proteins Ptgs2 and IL-6, and induced ROS in MC3T3-E1 osteoblastic cells. Angptl4 is an endogenous inhibitor of LPL which was transcriptionally induced by TGRL-LP, while recombinant Angptl4 prevented TG-driven Atf3 induction. Atf3 global knockout male mice demonstrated increased trabecular and cortical microarchitectural parameters. In summary, we find that TGRL-LP induce osteoblastic cell stress as evidenced by expression of ATF3, which may contribute to the negative impact of dyslipidemia in the skeleton. Further, concomitant induction of Angptl4 in osteoblasts might play a protective role by reducing local lipolysis.


Dyslipidemias , Lipolysis , Male , Animals , Mice , Lipolysis/physiology , Reactive Oxygen Species/metabolism , Activating Transcription Factor 3/genetics , Activating Transcription Factor 3/metabolism , Heat-Shock Proteins/metabolism , Triglycerides/metabolism , Lipoproteins/genetics , Lipoproteins/metabolism , Osteoblasts/metabolism
15.
Ann Hum Genet ; 88(3): 194-211, 2024 May.
Article En | MEDLINE | ID: mdl-38108658

Many inherited conditions cause hepatocellular cholestasis in infancy, including progressive familial intrahepatic cholestasis (PFIC), a heterogeneous group of diseases with highly overlapping symptoms. In our study, six unrelated Tunisian infants with PFIC suspicion were the subject of a panel-target sequencing followed by an exhaustive bioinformatic and modeling investigations. Results revealed five disease-causative variants including known ones: (the p.Asp482Gly and p.Tyr354 * in the ABCB11 gene and the p.Arg446 * in the ABCC2 gene), a novel p.Ala98Cys variant in the ATP-binding cassette subfamily G member 5 (ABCG5) gene and a first homozygous description of the p.Gln312His in the ABCB11 gene. The p.Gln312His disrupts the interaction pattern of the bile salt export pump as well as the flexibility of the second intracellular loop domain harboring this residue. As for the p.Ala98Cys, it modulates both the interactions within the first nucleotide-binding domain of the bile transporter and its accessibility. Two additional potentially modifier variants in cholestasis-associated genes were retained based on their pathogenicity (p.Gly758Val in the ABCC2 gene) and functionality (p.Asp19His in the ABCG8 gene). Molecular findings allowed a PFIC2 diagnosis in five patients and an unexpected diagnosis of sisterolemia in one case. The absence of genotype/phenotype correlation suggests the implication of environmental and epigenetic factors as well as modifier variants involved directly or indirectly in the bile composition, which could explain the cholestasis phenotypic variability.


Cholestasis, Intrahepatic , Cholestasis , Infant , Humans , Infant, Newborn , ATP Binding Cassette Transporter, Subfamily B, Member 11/genetics , ATP-Binding Cassette Transporters/genetics , Cholestasis, Intrahepatic/diagnosis , Cholestasis, Intrahepatic/genetics , Cholestasis/genetics , Genetic Association Studies , Mutation , ATP Binding Cassette Transporter, Subfamily G, Member 5/genetics , Lipoproteins/genetics
16.
Ticks Tick Borne Dis ; 15(1): 102287, 2024 01.
Article En | MEDLINE | ID: mdl-38016210

Lyme disease, or also known as Lyme borreliosis, is caused by the spirochetes belonging to the Borrelia burgdorferi sensu lato complex, which can enter the human body following the bite of an infected tick. Many membrane lipid-bound proteins, also known as lipoproteins, are located on the surface of B. burgdorferi sensu lato and play a crucial role in the spirochete to interact with its environment, whether in ticks or mammals. Since the spirochete needs to perform various tasks, such as resisting the host's immune system or spreading throughout the organism, it is not surprising that numerous surface proteins have been found to be essential for B. burgdorferi sensu lato complex bacteria in causing Lyme disease. In this study, we have determined (at 2.4 Å resolution) and characterized the 3D structure of BB0158, one of the few chromosomally encoded outer surface proteins from B. burgdorferi sensu stricto. BB0158 belongs to the paralogous gene family 44 (PFam44), consisting of four other members (BB0159, BBA04, BBE09 and BBK52). The characterization of BB0158, which appears to form a domain-swapped dimer, in conjunction with the characterization of the corresponding PFam44 members, certainly contribute to our understanding of B. burgdorferi sensu stricto proteins.


Borrelia burgdorferi Group , Borrelia burgdorferi , Lyme Disease , Ticks , Animals , Humans , Borrelia burgdorferi/genetics , Borrelia burgdorferi Group/genetics , Lipoproteins/genetics , Membrane Proteins , Mammals
17.
Atherosclerosis ; 388: 117397, 2024 Jan.
Article En | MEDLINE | ID: mdl-38102060

BACKGROUND: The relationship between genetically-driven liver fat and coronary heart disease (CHD) remains unclear. ApoB-containing lipoproteins are known causal factors for CHD and may explain this relationship. METHODS AND RESULTS: We conducted a genome-wide association study (GWAS) in the UK Biobank to identify genetic variants associated with liver fat. We then investigated the effects that these genetic variants had on both apoB-containing lipoproteins and CHD. Using Mendelian Randomization (MR) analyses, we examined if the relationship between genetically-driven liver fat and CHD could be attributed to its effect on apoB-containing lipoproteins. We found 25 independent liver-fat associated single-nucleotide polymorphisms (SNPs) with differing effects on lipoprotein metabolism. The SNPs were classified into three groups/clusters. The first cluster (N = 3 SNPs) displayed lipoprotein-raising effects. The second cluster (N = 12 SNPs) displayed neutral effects on lipoproteins and the third cluster (N = 10 SNPs) displayed lipoprotein-lowering effects. For every 1% higher liver fat, the first cluster showed an increased risk of CHD (OR = 1.157 [95% CI: 1.108-1.208]). The second cluster showed a non-significant effect on CHD (OR = 0.988 [95% CI: 0.965-1.012], whereas the third cluster showed a protective effect of increased liver fat on CHD (OR = 0.942 [95% CI: 0.897-0.989]). When adjusting for apoB, the risk for CHD became null. CONCLUSIONS: Here, we identify 25 liver-fat associated SNPs. We find that SNPs that increase, decrease or have neutral effects on apoB-containing lipoproteins show increased, decreased or neutral effects on CHD, respectively. Therefore, the relationship between genetically-driven liver fat and CHD is mediated by the causal effect of apoB.


Coronary Disease , Genome-Wide Association Study , Humans , Apolipoproteins B/genetics , Cholesterol, LDL/genetics , Coronary Disease/diagnosis , Coronary Disease/epidemiology , Coronary Disease/genetics , Lipoproteins/genetics , Liver , Mendelian Randomization Analysis
18.
Curr Microbiol ; 81(1): 36, 2023 Dec 08.
Article En | MEDLINE | ID: mdl-38063939

Staphylococcus aureus is one of the most prevalent bacteria found in acute wounds. S. aureus produces many virulence factors and extracellular enzymes that contribute to bacterial survival, dissemination, and pathogenicity. Lipase GehB is a glycerol ester hydrolase that hydrolyzes triglycerides to facilitate the evasion of S. aureus from host immune recognition. However, the role and mechanism of lipase GehB in skin acute wound healing after S. aureus infection remain unclear. In this study, we found that the gehB gene deletion mutant (USA300ΔgehB) stimulated significantly higher levels of pro-inflammatory cytokines in RAW264.7 and Toll-like receptor 2 (TLR2)-transfected HEK293 cells than the wild-type USA300 strain did. Recombinant GehB-His treated lipoprotein (Lpp) reduced stimulation of TLR2-dependent TNF-α production by RAW264.7 macrophages. GehB delayed the skin acute wound healing in BALB/c mice infected with S. aureus, while wound healing was similar in C57BL/6 TLR2-/- mice infected with either wild-type USA300 or USA300ΔgehB. In BALB/c mice, we also observed more bacterial survival, less leukocyte recruitment, lower IL-8 production, and adipocyte differentiation in USA300-infected skin acute wound tissues than those in USA300ΔgehB-challenged ones. Our data indicated that GehB inactivates lipoproteins to shield S. aureus from innate immune killing, resulting in delayed the healing of skin acute wounds infected with S. aureus.


Staphylococcal Infections , Staphylococcus aureus , Animals , Humans , Mice , HEK293 Cells , Lipase , Lipoproteins/genetics , Mice, Inbred C57BL , Staphylococcus aureus/genetics , Toll-Like Receptor 2/genetics , Wound Healing , Bacterial Proteins/metabolism
19.
J Lipid Res ; 64(12): 100471, 2023 12.
Article En | MEDLINE | ID: mdl-37944753

Despite great progress in understanding lipoprotein physiology, there is still much to be learned about the genetic drivers of lipoprotein abundance, composition, and function. We used ion mobility spectrometry to survey 16 plasma lipoprotein subfractions in 500 Diversity Outbred mice maintained on a Western-style diet. We identified 21 quantitative trait loci (QTL) affecting lipoprotein abundance. To refine the QTL and link them to disease risk in humans, we asked if the human homologs of genes located at each QTL were associated with lipid traits in human genome-wide association studies. Integration of mouse QTL with human genome-wide association studies yielded candidate gene drivers for 18 of the 21 QTL. This approach enabled us to nominate the gene encoding the neutral ceramidase, Asah2, as a novel candidate driver at a QTL on chromosome 19 for large HDL particles (HDL-2b). To experimentally validate Asah2, we surveyed lipoproteins in Asah2-/- mice. Compared to wild-type mice, female Asah2-/- mice showed an increase in several lipoproteins, including HDL. Our results provide insights into the genetic regulation of circulating lipoproteins, as well as mechanisms by which lipoprotein subfractions may affect cardiovascular disease risk in humans.


Collaborative Cross Mice , Genome-Wide Association Study , Female , Humans , Mice , Animals , Lipoproteins/genetics , Quantitative Trait Loci/genetics , Phenotype , Lipoproteins, VLDL
20.
Vet Res ; 54(1): 107, 2023 Nov 17.
Article En | MEDLINE | ID: mdl-37978536

Mycoplasma bovis is responsible for various inflammatory diseases in cattle. The prevention and control of M. bovis are complicated by the absence of effective vaccines and the emergence of multidrug-resistant strains, resulting in substantial economic losses worldwide in the cattle industry. Lipoproteins, vital components of the Mycoplasmas cell membrane, are deemed potent antigens for eliciting immune responses in the host upon infection. However, the functions of lipoproteins in M. bovis remain underexplored due to their low sequence similarity with those of other bacteria and the scarcity of genetic manipulation tools for M. bovis. In this study, the lipoprotein LppA was identified in all examined M. bovis strains. Utilizing immunoelectron microscopy and Western blotting, it was observed that LppA localizes to the surface membrane. Recombinant LppA demonstrated dose-dependent adherence to the membrane of embryonic bovine lung (EBL) cells, and this adhesion was inhibited by anti-LppA serum. In vitro binding assays confirmed LppA's ability to associate with fibronectin, collagen IV, laminin, vitronectin, plasminogen, and tPA, thereby facilitating the conversion of plasminogen to plasmin. Moreover, LppA was found to bind and enhance the accumulation of Annexin A2 (ANXA2) on the cell membrane. Disrupting LppA in M. bovis significantly diminished the bacterium's capacity to adhere to EBL cells, underscoring LppA's function as a bacterial adhesin. In conclusion, LppA emerges as a novel adhesion protein that interacts with multiple host extracellular matrix proteins and ANXA2, playing a crucial role in M. bovis's adherence to host cells and dissemination. These insights substantially deepen our comprehension of the molecular pathogenesis of M. bovis.


Annexin A2 , Cattle Diseases , Mycoplasma Infections , Mycoplasma bovis , Animals , Cattle , Mycoplasma bovis/physiology , Bacterial Adhesion/physiology , Plasminogen/metabolism , Annexin A2/metabolism , Lipoproteins/genetics , Extracellular Matrix , Mycoplasma Infections/veterinary , Mycoplasma Infections/microbiology , Cattle Diseases/microbiology
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