bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracellular vesicles isolated from human mesenchymal stem cells promote resolution of pulmonary fibrosis
Authors: Shentu Tzu Pin , Wong Simon , Espinoza Celia , Cernelc‐Kohan Mateja , Hagood James
Published: November 2023

The recent discovery of therapeutic applications of extracellular vesicles (EVs) released from human mesenchymal stem cells (hMSCs) has generated interest in their mechanisms of targeting and action. The aim of this study was to explore the role of hMSC‐derived EVs in pulmonary fibrosis. An in vivo efficacy study demonstrated that delivery of hMSC‐EVs (50 μg protein, iv.) at day 14 in mice with pulmonary fibrosis induced by intratracheal bleomycin significantly down‐regulated α‐smooth muscle actin (αSMA) expression and improved histopathological fibrosis, indicating therapeutic effects of these vesicles for established lung fibrosis through modification of the myofibroblastic phenotype; Pretreatment of hMSC‐EVs with antibody to hThy‐1 blocked the effects, suggesting Thy‐1, a cell surface glycoprotein, is essential for the beneficial effects. In vitro studies demonstrated that hMSC‐EVs with membrane‐anchored Thy‐1 display increased cellular uptake by lung fibroblasts in time and dose‐dependent manners as compared to EVs derived from fibroblasts. Removal or blocking of Thy‐1 by phosphatidylinositol specific phospholipase C (PI‐PLC) or anti‐Thy‐1 antibody decreased the uptake of EVs. Cellular uptakes of hMSC‐EVs (10 μg/ml) significantly suppressed TGFb1‐induced pro‐fibrotic gene expression in vitro. Thy‐1 blockade abrogates the rescue effects of hMSC‐EVs. Our novel findings indicate that hMSC–derived EVs exert antifibrotic effects relevant to pulmonary fibrosis, dependent on surface expression of Thy‐1.
Surface Topography During Neural Stem Cell Differentiation Regulates Cell Migration and Cell Morphology
Authors: Czeisler Catherine , Short Aaron , Stocker Ben , Cronin James , Lannutti John , Winter Jessica , Otero Jose Javier
Published: November 2023

We sought to determine the contribution of scaffold topography to the migration and morphology of neural stem cells by mimicking features of scaffolds found in vivo. We mimicked two types of CNS scaffolds encountered by neural stem cells during development in vitro by constructing different diameter electrospun polycaprolactone (PCL) fiber mats, a substrate that we have shown to be topographically similar to brain scaffolds. We compared the effects of large fibers (made to mimic blood vessel topography) with those of small diameter fibers (made to mimic radial glial process topography) on the migration and differentiation of neural stem cells. Neural stem cells showed differential migratory and morphological reactions with laminin in different topographical contexts. We demonstrate, for the first time, that neural stem cell biological responses to laminin are dependent on topographical context. Topography‐induced cell morphology changes were inhibited by nocodazole, but not by cytochalasin‐D or ROCK‐inhibitor, suggesting that microtubule function is necessary for topography‐induced morphology changes. We propose that the physical structure of distinct scaffolds induces unique signaling cascades that regulate migration and morphology in embryonic neural progenitor cells.

Support or Funding Information

BS acknowledges Pelotonia Foundation Undergraduate Research Fellowship. AS acknowledges The Ohio State University/Metro High School Graduate Teaching Assistant Fellowship. The project described was supported by Award Number Grant 8UL1TR000090‐05, from the National Center for Advancing Translational Sciences. The content is solely the responsibility of the authors and does not necessarily represent official views of the National Center for Advancing Translational Sciences or the National Institutes of Health. This work was sponsored by and represents activity of The Ohio State University Center for Regenerative Medicine and Cell Based Therapies (regenerativemedicine.osu.edu).
Neuropilin 2 Deficiency Prolongs Skin Inflammation and Edema
Authors: Bielenberg Diane Renee , Mucka Patrick , Levonyak Nicholas , Geretti Elena , Zwaans Bernadette M.M. , Li Xiaoran , Adini Irit , Klagsbrun Michael , Adam Rosalyn M
Published: November 2023

The vasculature is involved in the progression and resolution of inflammation. Blood and lymphatic capillaries express vascular endothelial growth factor (VEGF) receptors that regulate fluid flow into and out of the interstitium. Neuropilin 2 (Nrp2), a unique receptor that binds VEGF‐A, VEGF‐C/D or semaphorin 3F (SEMA3F) ligands, is expressed by the endothelium during development but downregulated after birth. Mice lacking Nrp2 are viable into adulthood without signs of edema. Herein, we investigated the expression and function of Nrp2 in a model of acute inflammation. Immunoblotting and X‐gal staining of Nrp2+/LacZ mice showed increased Nrp2 or b‐galactosidase activity in the endothelium following delayed‐type hypersensitivity (DTH) reactions. Nrp2−/− mice exhibited massive tissue swelling, prolonged lymphedema, and delayed resolution after DTH compared to wild‐type mice. Vascular permeability was two‐fold higher in inflamed blood vessels in Nrp2‐deficient mice compared to Nrp2‐intact littermates. Histological examination revealed a lack of superficial lymphatic capillaries in Nrp2‐mutant mice. Addition of exogenous SEMA3F protein inhibited VEGFA‐induced vascular permeability in wild‐type mice. In summary, Nrp2 deficiency increased blood vessel permeability and decreased lymphatic vessel drainage during inflammation. Taken together our data suggest that Nrp2 is upregulated in the endothelium to modulate inflammation‐induced tissue swelling and resolve post‐inflammatory edema.

Support or Funding Information

Vascular Biology Program, Boston Children's Hospital; NCI and NIDDK under award numbers CA118732, CA155728 (D.R.B.), CA037392 (M.K.), and DK65298 (R.M.A.).
Transdifferentiation of Chondrocytes to Osteoblasts during Bone Fracture Healing
Authors: Marcucio Ralph , Hu Diane , Yang Frank , Bahney Chelsea , Miclau Theodore
Published: November 2023

For more than 150 years, dogma has been that cartilage is replaced by bone during endochondral ossification. This is thought to be true during development and this process is recapitulated during repair of fractured bones. During endochondral ossification mesenchymal cells condense and differentiate into chondrocytes. The chondrocytes mature, become hypertrophic, and induce vascular invasion of the cartilage matrix. The currently accepted model states that chondrocytes undergo apoptosis and osteoblast progenitor cells are delivered to the cartilage by the invading vasculature to replace the cartilage with bone. However, recent data from our laboratory indicates that this model is incorrect. Chondrocytes undergo a transformation during bone fracture healing to become osteoblasts that make the new bone matrix. This process occurs in a region that we named “the transition zone” that is located adjacent to the invading vasculature. Chondrocytes located in the transition have two fates. Some of the chondrocytes die, while others re‐enter the cell cycle, switch off the chondrogenic program, activate the molecular program associated with pluripotency, activate the molecular program associated with osteogenesis, and synthesize new bone matrix via perilacunar remodeling, possibly in response to signals from the invading vasculature. Others have recognized this process in many contexts. In fact, in the early to middle 1800's metaplasia of cartilage to bone was considered to be the mechanism of bone formation. Our data support this model and indicate that the main process of bone formation is by direct transformation of chondrocytes to osteoblasts during bone fracture healing.

Support or Funding Information

NIH: NIAMS: F32AR062469 to C.B., R01‐AR057344 to T.M., NIA: R01‐AG046282 to R.M. MTF Junior Investigator Award to C.B.
Exploring Cranial Functional Morphology and Evolution through the Jaws of Alligators
Authors: Holliday Casey M
Published: November 2023

Among all of the extraordinary examples of vertebrate cranial adaptation, few are as iconic as the heads of alligators and their crocodilian relatives. Despite their inclusion in centuries of paleontological, anatomical and experimental work, these underutilized model organisms remain fonts of discovery in biomechanics, physiology, development and evolution. Although their remarkable feeding behaviors and familiar cranial shapes underlie many lines of inquiry, few studies have focused on the role of various cranial articulations within the feeding apparatus. Here I present a series of recent projects investigating the alligator and crocodyliform feeding apparatus with a focus on cranial articulations incorporating multiple lines of evidence combining anatomical techniques, imaging, mechanical testing, computational modeling and the fossil record. This comprehensive research program has built a solid foundation necessary for testing hypotheses of skeletal tissue regulation, adaptive plasticity, cranial kinesis, and ecomorphology in not only crocodilians, but other vertebrate clades. For example, comparative anatomical methods reveal the mandibular symphysis to be a complicated syndesmosis surrounding a synchondrosis formed by fused Meckel's cartilages, which grows throughout life. Morphometric approaches quantify how the characteristic Class 3 symphyseal plate increases in complexity during ontogeny and varies among other crocodylian species. Mechanical testing reveals how the symphysis is capable of withstanding such extreme bite forces. 3D visualization illustrates how jaw musculature changes orientation during gape cycles, ontogeny and evolution. Finally, biomechanical modeling accurately predicts how muscles and feeding forces load the symphysis and other cranial joints during different feeding behaviors. Results stemming from these Alligator projects have undeniably shed light on crocodyliform and suchian function, ecology and evolution, but more importantly, they have inspired new interdisciplinary collaborations investigating broader topics in vertebrate evolution including homoplasy in beak evolution, thermoregulatory adaptations of the temporal region, and the origin of the mammalian temporomandibular joint. Therefore, crocodilians are more than just ‘living fossils’ but instead are a gateway to new exploration of the complex patterns and processes underlying vertebrate evolution.

Support or Funding Information

This work was funded by NSF IOS 1457319, Missouri Research Board, Missouri Research Council, and the Department of Pathology and Anatomical Sciences.
Molecular Switches In Proteasome Assembly : Tales Of The Tails And Chaperones
Authors: Park Soyeon
Published: November 2023

In the proteasome, the proteolytic 20S core particle (CP) associates with the 19S regulatory particle (RP) to degrade polyubiquitinated proteins. Six ATPases (Rpt1‐Rpt6) of the RP form a hexameric Rpt ring and interact with the heptameric α ring (α1–α7) of the CP via the Rpt C‐terminal tails individually binding to the α subunits. Importantly, the Rpt6 tail has been suggested to be crucial for RP assembly. Here, we show that the interaction of the CP and Rpt6 tail promotes a CP‐Rpt3 tail interaction, and that they jointly mediate proteasome activation via opening the CP gate for substrate entry. The Rpt6 tail forms a novel relationship with the Nas6 chaperone, which binds to Rpt3 and regulates the CP‐Rpt3 tail interaction, critically influencing cell growth and turnover of polyubiquitinated proteins. CP‐Rpt6 tail binding promotes the release of Nas6 from the proteasome. Based on disulfide crosslinking that detects cognate α3‐Rpt6 tail and α2‐Rpt3 tail interactions in the proteasome, decreased α3‐Rpt6 tail interaction facilitates robust α2‐Rpt3 tail interaction that is also strongly ATP‐dependent. Together, our data support the reported role of Rpt6 during proteasome assembly, and suggest that its function switches from anchoring for RP assembly into promoting Rpt3‐dependent activation of the mature proteasome.

Support or Funding Information

This study was supported by the University of Colorado start‐up fund and Boettcher Web‐Warring Biomedical Research Award to S.P.
Trans‐Translation As A Target For Novel Antibiotics
Authors: Keiler Kenneth
Published: November 2023

The trans‐translation pathway rescues ribosomes stalled at the end of mRNAs in bacteria. This pathway is required for viability or virulence in many species, but is not targeted by existing antibiotics. Using a high‐throughput screen, we identified compounds that inhibit trans‐translation but not protein synthesis. These compounds are not toxic to eukaryotic cells, but inhibit growth of a broad spectrum of bacterial species, including Staphylococcus aureus, Bacillus anthracis, Shigella flexneri, Mycobacterium tuberculosis, and Francisella tularensis, both in vitro and during ex vivo infection. Chemical cross‐linking was used to determine the molecular targets of these compounds in bacteria. One family of inhibitors was found to bind to the base of helix 89 in 23S rRNA, a site that is not bound by other antibiotics. These data validate trans‐translation as a target for antibiotic development and provide new insights into the early steps of ribosome rescue pathways.

Support or Funding Information

This work was supported by grants GM068720 and AI111692 from the National Institutes of Health.
Transcriptional Control of Lipid Homeostasis
Authors: Totonoz Peter
Published: November 2023

Control of lipid abundance and organization is essential for life. Dysregulation of lipid homeostasis is linked to common diseases, including diabetes, obesity, and atherosclerosis. Our long‐term goal is to understand the mechanisms whereby lipids control gene expression and impact the development of metabolic disease. We have used the transcriptional program controlled by the lipid‐activated nuclear receptor LXR as a Rosetta stone to uncover fundamental mechanisms involved in lipid metabolism and inflammation potential opportunities for drug development. LXR signaling is critical for the maintenance of cellular and systemic cholesterol balance in mammals. LXRs coordinately regulate the expression of a battery of target genes involved in the uptake, efflux, transport and elimination of sterols. The LXR pathway is an important counterpoint to the SREBP pathway, which regulates lipid synthesis, and there are multiple mechanisms for crosstalk and integration. LXR target genes are highly represented in GWAS for plasma lipid levels and coronary artery disease, underscoring the relevance of LXR signaling for human biology. Recent work has focused on three key mediators of LXR action: Idol–which controls lipoprotein receptor activity, and Lpcat3 and Abca1–which control membrane composition. Delineation of these pathways has revealed new regulatory concepts and brought insights with implications beyond the field of lipid metabolism.

Support or Funding Information

NIH‐NHLBI NATIONAL HEART, LUNG, AND BLOOD INSTITUT
A Description of the First Year of the New MCAT® Exam
Authors: Kroopnick Marc
Published: November 2023

The new Medical College Admission Test (MCAT®) was introduced in April of 2015. Highlights of the new exam content include the organization around competencies, use of interdisciplinary life sciences passage sets, the inclusion of biochemistry content, and the introduction of a test section that focuses on the behavioral and social sciences. The competencies that include biochemistry content can be found in two of the four test sections— specifically, the Biological and Biochemical Foundations of Living Systems section as well as the Chemical and Physical Foundations of Biological Systems section. This presentation will review the content of the new exam, provide an overview of examinee performance in the first testing year, and describe the test preparation resources that are available to prospective examinees.
Transcription And The Maintenance Of Genome Stability
Authors: Svejstrup Jesper Q , Williamson Laura , Saponaro Marco , Boeing Stefan , Mitter Richard , Kelly Gavin
Published: November 2023

Over the last decade it has become increasingly evident that transcription is closely integrated with other DNA‐related processes, such as chromatin dynamics, DNA replication and repair. Indeed, the essential process of expressing genes comes at a cost: the movement of RNA polymerases through chromatin is associated with significant genome instability. RNA Polymerase II stalling, arrest, and/or backtracking ‐ collectively referred to as transcription stress ‐ thus generates a cellular response akin to the DNA damage response, and constantly needs to be contended with to avoid DNA damage. The factors and mechanisms involved in suppressing transcription‐associated genome instability remain poorly understood. Conversely, DNA damage itself, such as that induced by UV‐irradiation, also greatly affects transcription. Indeed, UV‐damage triggers rapid reduction in global RNA synthesis and changes to mRNA splicing, but the molecular details and underlying mechanisms again remain unclear. In this talk, our recent advances in understanding the interface between transcription and the maintenance of genome integrity will be outlined.

Support or Funding Information

Supported by grants from the ERC and the Francis Crick Institute
Endocytosis Separates EGF Receptors From Endogenous Fluorescently Labeled HRas and Prevents Receptor Signaling to MAP Kinases in Endosomes
Authors: Sorkin Alexander , Pinilla‐Macua Itziar
Published: November 2023

Signaling from epidermal growth factor receptor (EGFR) to extracellular‐stimuli‐regulated protein kinase 1/2 (ERK1/2) is proposed to be transduced not only from the cell surface but also from endosomes, although the role of endocytosis in this signaling pathway is controversial. Ras is the only membrane‐anchored component in the EGFR‐ERK signaling axis, and therefore, its location determines intracellular sites of downstream signaling. However, Ras localization was studied predominantly in overexpression systems. Hence we labeled endogenous HRas with mVenus fluorescent protein using genome‐editing in HeLa cells. mVenus‐HRas was primarily located at the plasma membrane, and in small amounts in tubular recycling endosomes and associated vesicles. EGF stimulation resulted in fast but transient activation of mVenus‐HRas. While EGF:EGFR complexes were rapidly accumulated in endosomes together with the Grb2 adaptor, no mVenus‐HRas was detected in these endosomes. Interestingly, the activities of MEK1/2 and ERK1/2 remained high beyond the point of the physical separation of HRas from EGF:EGFR complexes and down‐regulation of Ras activity. Paradoxically, this sustained MEK1/2 and ERK1/2 activation was dependent on the active EGFR kinase. Cell‐surface biotinylation and selective inactivation of surface EGFRs suggested that a small fraction of active EGFRs remaining in the plasma membrane is responsible for continuous signaling to MEK1/2 and ERK1/2. We propose that under physiological conditions of cell stimulation, EGFR endocytosis serves to spatially separate EGFR‐Grb2 complexes and Ras, thus terminating Ras‐mediated signaling. However, sustained minimal activation of Ras by a small pool of active EGFRs in the plasma membrane is sufficient for extending MEK1/2 and ERK1/2 activities.

Support or Funding Information

This work was supported by NCI CA089151 grant.
The Early Origins of NAFLD in Humans and Non‐Human Primates
Authors: Friedman Jacob E
Published: November 2023

Non‐Alcoholic Fatty Liver Disease (NAFLD) is now the most common liver disease worldwide in children and adults. Even more concerning is that the risk factors for NAFLD may start operating in early life. In the U.S., up to 25% of children are already overweight or obese entering kindergarten, and maternal obesity is consistently one of the most powerful predictors of pediatric obesity and its complications. NAFLD is currently estimated to occur in 25–50% of obese children with lifetime consequences, including liver NASH and hepatic carcinoma risk. Our group has spent the past decade studying developmental programming in humans, non‐human primates (NHP), and transgenic mouse models. We have shown that maternal Western‐Style Diet (WSD) in NHP mothers results in a NAFLD phenotype in the fetus, beginning in the early 3rd trimester. This phenotype persists in juveniles up to 14 months of age despite weaning to a healthy diet, and in the absence of obesity. Our compelling human data in neonates born to obese/Gestational Diabetic mothers demonstrate increased intrahepatic fat using MRI/MRS at 2 wks of life. However not everyone who is born to an obese mother develops disease, with other potential contributing factors particularly excessive maternal insulin resistance, hypoxia, and mitochondria dysfunction important in the fetal development of NAFLD. Our studies in obese NHP mothers using the anti‐oxidant resveratrol, may be able to mitigate some of these complications to prevent the early complications of maternal obesity on the developing liver. Interestingly, founding individual microbiota composition in infants reflects the maternal transfer during or immediately after birth. The intestinal microflora is different between individuals and its composition is largely dependent on a combination of genetics, diet and lifestyle choices. Although no single commensal bacteria species have been conclusively proven to provoke NAFLD, lack of certain bacterial species has been observed with human patients prone to or suffering from this disorder. In cross‐sectional studies comparing vaginally delivered, exclusively breast fed infants we have found a significant reduction in the early pioneering bacteria Gammaproteobacteria in 2 week old infants from obese mothers compared to infants born to normal weight mothers. Further, gnotobiotic transfer of stool from infants of obese mothers into germ‐free mice was associated with a significant reduction in IL‐10 producing anti‐inflammatory Treg cells, as well as CD3+CD4+ helper T‐cells and ER stress in the liver at 21 days post‐transplantation. These findings suggest that early commensal bacteria from obese human infants may be important in conditioning a developing immune system that educates inflammatory cells, leading to inflammation‐linked diseases, including NAFLD, a hypothesis we are currently exploring.

Support or Funding Information

NIH‐NIDDK, ADA, and Bill Gates Foundation
Periodontal symptoms and inflammation following non‐surgical treatment and 4 months of fish oil supplementation
Authors: Coates Alison , Fitzsimmons Tracy , Chee Brian , Park Boram , Kapellas Kostas , Howe Peter , Lee Ryan , Ivanovski Saso
Published: November 2023

Background/Aims

Periodontitis is a chronic inflammatory condition characterised by destruction of the supporting apparatus of teeth, including bone and the periodontal ligament. Long chain omega‐3 polyunsaturated fatty acids (LCn‐3PUFA) in fish oil are beneficial for several inflammatory conditions with mixed findings in periodontitis. We evaluated the clinical efficacy of fish oil supplementation as an adjunct to standard therapy for advanced chronic periodontitis.

Methods

In a 4 month randomised, controlled parallel study participants with advanced chronic periodontitis (10M/23F, mean age 52 ± 10 years) consumed either fish oil (1884 mg LCn‐ 3PUFA /day) or (2000 mg soy oil /day). Patients were assessed at baseline and after 4 months for clinical outcomes, viz. probing pocket depth (PPD) and clinical attachment (CAL), inflammatory cytokines (TNF‐alpha, IL‐1beta and C‐reactive protein) in gingival crevicular fluid (GCF) and fasting blood samples were assessed for LCn‐3PUFA erythrocyte content to determine compliance.

Results

Following non‐surgical treatment and 4 months of oil supplementation both groups had improvements in clinical outcomes, with significant reductions in PPD and CAL gain. There was no significant difference between groups in the percentage of sites that had ≥2 mm gain of CAL (P = 0.229) or reduction in PPD (P = 0.264) after 4 months. There were no significant changes in cytokines in GCF in either group. Erythrocyte LCn‐3PUFA increased by 50% in the fish oil supplemented group with no change in the placebo group suggesting good compliance with supplementation.

Conclusions

Whilst periodontal treatment was effective in all participants, no additional benefit was observed with fish oil supplementation for 4 months.

Support or Funding Information

Australian Dental Research Foundation grants (2013 and 2014); Novasel Australia LTD donated the capsules.
Initial Results from a Real‐world Pediatric Specialty Weight Management Clinic in a Safety‐net Hospital
Authors: Lenders Carine M , Plourde Kendra Davis , Manders Aaron J , Ireland Kathy
Published: November 2023

Background

There is limited data available on anthropometric outcomes from specialty pediatric obesity clinics targeting underserved populations. There is increasing evidence that interventions in early childhood are critical.

Objectives

To identify changes in weight measures in a pediatric obesity specialty clinic (Nutrition and Fitness for Life program, NFL) at a safety‐net hospital (Boston Medical Center, BMC). To determine the prevalence of children with clinically relevant reductions in weight measures.

Methods

This is a prospective observational study using data from a clinical data warehouse. Patients evaluated in the NFL clinic are referred by clinicians from BMC and associated health centers. Data from 795 patients seen between 2003 and 2010 was extracted. The criteria for inclusion in the study was being age 2–18 years old and attending at least two office visits. Data was extracted for weight, height, age at first and last visit, sex, and insurance status. We present data on weight, BMI, and BMI z‐score change and the prevalence of children with more than 5% reduction in BMI and BMI z‐scores. Other weight measures are being examined. CDC references were used and descriptive analyses performed.

Results

Given the study inclusion criteria, the final sample consisted of 544 patients with a median (IQ) for age of 11.5 (9.1, 13.9) years, 45% were male, 63% were on public insurance, 57% were Black or African American, 29% Hispanic, 7% White, and 7% Other. The median (IQ) treatment period was 6(3; 14.5) months. Baseline BMI was 32.1(28.4; 37.7) kg/m2, percentile was 99.4(98.9; 99.7), and z‐score was 2.5(2.3–2.7) s.d. Overall, patients’ BMI increased by 1 (−1.6; 4.6) kg/m2 and decreased by −0.8 (−4.1; 0.9) z‐score during the treatment period. Weight, BMI and BMI z‐score reductions of more than 5% varied significantly by age group.

Discussion

Despite socioeconomic challenges and the lack of exclusions, children were able to improve their weight measures. Overall the results in children less than six years old were encouraging. However, there is a lot of controversies on what weight loss indicator to use given the lack of references for severe obesity. There is a need for standardized measures of effectiveness in specialty obesity clinics that target underserved pediatric populations.

Support or Funding Information

Support from New Balance Foundation.

Percent of children with more than 5% reduction in weight measure

2–5.9 y(N=47)
6–11.9 y (n=247)
12–18.9 y (N=250)

n(%)
n(%)
n(%)
p‐value

>5% wt Loss
2(4%)
1(0.4%)
22(9%)
< 0.0001

>5% BMI Loss
6(13%)
13(5%)
29(12%)
0.0274

>5% BMI z‐score loss
29(62%)
43(17%)
36(14%)
<0.0001
Ablation of BCO2 Leads to Increased Susceptibility to High Fat Diet‐induced Metabolic Disorders in Mice
Authors: Wu Lei , Guo Xin , Davis Abby , Soh Traces Petchdee , Clarke Stephen , Lucas Edralin , Smith Brenda , Wang Weiqun , Medeiros Denis , Lin Dingbo
Published: November 2023

Objective

β,β‐carotene‐9′, 10′‐dioxygenase 2 (BCO2) is a carotenoid cleavage enzyme located on the inner membrane of the mitochondria. We recently reported that BCO2 protein expression is reduced in obese/diabetic mice and ablation of BCO2 impairs mitochondrial function. The purpose of this study is to determine whether ablation of the BCO2 protein leads to increased susceptibility to high fat diet (HFD)‐induced metabolic disorders.

Methods

Six week old male BCO2 knockout (KO) and wild type (WT, 129S6) mice were fed a HFD (45 kCal % from fat) or a low fat diet (LFD, 10 kCal % from fat) for 28 weeks. On the 27th week of study, mice were subjected to pyruvate, glucose, and insulin tolerance tests. At termination of the study, blood, liver and white adipose tissues (WAT) were collected. Plasma biomarkers of metabolic disorders were tested, including glucagon, insulin, leptin, cholesterol, lipoproteins, triglycerides (TG), nonesterified fatty acids (NEFA), and inflammatory cytokines. Fresh hepatic mitochondria were isolated and subjected to mitochondrial respiratory function assays. Real time PCR and Western blot were employed to determine altered metabolic pathways. Histological changes and fat deposition in liver tissues were monitored by H &E and oil red O staining, respectively.

Results

After the 28‐week intervention, there were no differences in food intake, body and WAT weights in both strains of mice fed LFD. However, the KO mice fed the HFD consumed significantly more food, gained more body and WAT weights, and had a significantly elevated fasting blood glucose level, compared to WT. Tolerance tests showed that KO mice developed intolerance to glucose, insulin, and pyruvate, suggesting enhanced gluconeogenesis, dyslipidemia, and hyperglycemia. Assessment of hepatic mitochondrial function revealed, the KO mice on the HFD, compared to WT mice fed with HFD, exhibited a mitochondrial proton leak, characterized by increased respiratory activity of electron transport chain complex II and IV. These findings are consistent with hyperactive and dysfunctional mitochondria. Further, KO mice fed a HFD had higher levels of circulatory NEFA, cholesterol, LDL and the pro‐inflammatory cytokine, interleukin (IL)‐18, suggestive of chronic inflammation.

Conclusions

The ablation of BCO2 causes mitochondrial dysfunction/hyperactivation and chronic inflammation, which may contribute to the development of metabolic disorders, including dyslipidemia, hyperglycemia and insulin resistance in mice fed a HFD.
Obesity is associated with distinct changes in the human plasma phospholipidome
Authors: Pickens Charles Austin , Jones Daniel , Fenton Jenifer I.
Published: November 2023

Obesity alters the composition of plasma and tissue fatty acids (FAs), which contributes to inflammation and insulin resistance. Several studies have reported obesity and insulin resistance are associated with altered levels of linoleic (18:2), dihomo‐gamma linolenic (20:3), arachidonic (20:4), and nervonic (24:1) acid in total plasma phospholipids (PPLs). However, few researchers have investigated whether these FA changes are specific to individual phospholipid (PL) classes (e.g., phosphatidylcholines [PCs], sphingomyelins [SMs]). The objective of this study was to determine whether specific PPL species containing 18:2, 20:3, 20:4, and 24:1 in plasma are associated with obesity. At time of enrollment, blood samples were collected from fasting subjects (males ages 48–65). Plasma was separated and stored at −80ºC until analysis. Crude plasma lipid extracts were analyzed using UPLC‐MS on a QTof mass spectrometer using reversed phase UPLC, electrospray ionization, and non‐selective multiplexed collision‐induced dissociation in negative‐ion mode. Data were processed using MarkerLynx version 4.1 which identified 410 lipids. Orthogonal partial least square discriminant analysis (OPLS‐DA) was used to compare obese (n=52) to lean (n=28) individuals and to generate an S‐plot of PL variables of importance (VIP) that distinguish obese from lean PL profiles. VIPs >2 were tested for statistical differences between lean and obese individuals using a Mann‐Whitney nonparametric U‐test. Obesity was inversely associated with the following PL species: lysoPC(18:2) p<0.0005, lysophosphatidylethanolamine(18:2) p<0.01, PC(plasmenyl‐16:0/18:2) p<0.0001, and SM(d18:2/24:1) p<0.05. Obesity was positively associated with PC(16:0/20:3) p<0.0001, PC(18:0/20:3) p<0.0001, and PC(16:0/20:4) p<0.0005. Therefore, we suggest that the previously reported changes in PPL 18:2, 20:3, 20:4, and 24:1 likely occur in these specific PL species. Future studies should investigate whether and how altered levels of these PL species influence obesity‐associated pathologies and examine their usefulness as predictive biomarkers of metabolic dysregulation.

Support or Funding Information

Research Support: NIH R03CA142000 and MSU CTSI
Cholesterol homeostasis alters one carbon metabolism in vitro and in vivo
Authors: Ko Hsin‐An Shawn , Wu Yi‐Ting Isabel , Sou Nga‐Lai Shawn , Chiang En‐Pei Isabel
Published: November 2023

Cholesterol essential for the synthesis of steroid hormones, bile acids, and lipoproteins. Hyperhomocysteinemia and hypercholesterolemia are both risk factors for human cardiovascular diseases. Previous studies reported that cholesterol biosynthesis can be regulated by homocysteine‐induced endoplasmic reticulum stress in primary human umbilical vein endothelial cells (HUVEC), hepatocellular carcinoma cell line (HepG2), and in murine models. However, the physiological impact of excessive cholesterol exposure on one‐carbon metabolism is unknown. We hypothesize that cholesterol may alter methionine adenosyltransferase 1A (MAT1a) expression via sterol regulatory element‐binding proteins (SREBPs) that have been shown to target the promoter of MAT1a gene. Physiological doses of cholesterol or mevastatin, an inhibitor of cholesterol synthesis, were used to alter cellular cholesterol contents in liver derived cell lines L02. Mice fed high cholesterol diets or cholesterol‐lowering drugs were used as in vivo models. We discovered that ratios of nuclear/ total SREBPs tended were altered by cholesterol and mevestatin treatments in the cell models. Furthermore, reporter assay demonstrated that cholesterol treatment but not mevastatin significantly increased MAT1a promoter activity, supporting our hypothesis. Preliminary data from stable isotopic tracer experiments also showed consistent results that cholesterol alters MAT expression and S‐adenosyl‐ methionine synthesis in vitro. We demonstrated novel findings on how cholesterol homeostasis interacts with methyl group kinetics in mammalian cells. The in vivo kinetics studies on how cholesterol affect one carbon metabolism are underway.

Support or Funding Information

MOST 104‐2320‐B005‐010‐MY3; MOST104‐2911‐I005‐301; Ministry of Education, Taiwan, R.O.C. under the ATU plan
One‐Carbon Metabolic Kinetics in Human Disease Models
Authors: Chiang EnPei Isabel , Wang Yi‐Cheng , Wu Ming‐Tsung , Lin Yan‐Jun , Ko Hsin‐An , Huang Yu‐ Hsuan , Sou Nga‐Lai , Chen Yi‐Ming , Tang Feng‐Yao
Published: November 2023

The polymorphisms in MTHFR have been associated with altered risk of numerous human cancers whereas GNMT is commonly diminished in human hepatoma. Folate‐mediated one‐carbon metabolism is an important therapeutic target of many human diseases including cancer. We extensively investigated how gene‐nutrient interactions may modulate human cancer risk in 2 major folate metabolic genes: MTHFR and GNMT. To further understand the metabolic roles of these genes in human disease progression, the biochemical impacts of gene alterations were carefully investigated: methyl group supply, global DNA methylation, nucleotide biosynthesis, DNA damage, and partitioning of the folate dependent 1‐carbon groups. The distinct model systems used included: EB virus‐transformed lymphoblasts expressing human polymorphic genotypes; liver‐derived transformed cell‐lines with and without overexpression of the target gene; and cells with stabilized inhibition using shRNA. We discovered that the genotype with reduced MTHFR function significantly reduces folate‐dependent remethylation under folate restriction, but it assists purine synthesis when folate is adequate. The advantage of de novo purine synthesis found in the MTHFR TT genotype may account for the protective effect of MTHFR in human hematological malignancies. Furthermore, GNMT affects transmethylation kinetics, S‐adenosylmethionine synthesis, and facilitates the conservation of methyl groups by limiting homocysteine remethylation fluxes. Restoring GNMT assists methylfolate‐dependent reactions and ameliorates the consequences of folate depletion. GNMT expression in vivo improves folate retention and bioavailability in the liver. Loss of GNMT impairs nucleotide biosynthesis. Over‐expression of GNMT enhances nucleotide biosynthesis and improves DNA integrity by reducing uracil misincorporation in DNA both in vitro and in vivo. Our systematic series of studies give new insights into the underlying mechanisms by which MTHFR and GNMT may participate in human tumor prevention and progression.

Support or Funding Information

MOST 104‐2320‐B005‐010‐MY3; MOST104‐2911‐I005‐301, Ministry of Education, Taiwan, R.O.C. under the ATU plan
Food Insecurity is Associated with Faster Cognitive Decline: Boston Puerto Rican Health Study
Authors: Wong Janice , Scott Tammy , Wilde Parke , Li Yinge , Tucker Katherine L. , Gao Xiang
Published: November 2023

BACKGROUND

Food insecurity ‐ living with hunger and fear of not having enough food ‐ is a growing worldwide concern, due to an imbalance between rapidly increasing demand for food and limited access to good quality foods. In our previous cross‐sectional study, we found that food insecurity was associated with poor cognitive function, but the direction of this relationship remains unclear.

OBJECTIVES

To investigate whether food insecurity is associated with development of cognitive decline.

DESIGN

The current prospective analysis was based on 597 Puerto Rican adults aged 40–75 with mini‐mental status exam (MMSE) ≥ 24 at baseline. Food security was assessed at baseline with the US Household Food Security Scale. Participants completed cognitive batteries (MMSE, word list learning, digit span, Stroop test, verbal fluency, clock drawing, figure copying) at baseline and two‐year follow‐up. The primary outcome was the change in global cognitive function over 2 years, averaging standardized scores across all cognitive tests.

RESULTS

Food insecurity at baseline was significantly associated with 2 year decline in global cognitive function (p trend = 0.03), after adjusting for baseline global cognitive score, age, education, APOE status, diet quality score, serum homocysteine concentration, depression and other potential confounders. The association between food security and cognitive decline tended to be more pronounced in participants who were below the poverty line or those with better cognitive function at the baseline (MMSE ≥ 27), relative to the other participants (p interaction<0.1 for both).

CONCLUSIONS

Food insecurity is associated with cognitive decline in this population with high risk of food insecurity and cognitive impairment.

Support or Funding Information

This work was supported by NIH grants P01 AG023394, and P50 HL105185.
EFFECTS OF METFORMIN EXPOSURE DURING LACTATION ON MOUSE OFFSPRING METABOLIC HEALTH AND MATERNAL LACTATION CHARACTERISTICS
Authors: Gregg Brigid , Brill Joshua , Botezatu Nathalie , Smith Michelle R
Published: November 2023

Background

Metformin administration during pregnancy has become more accepted as clinical trials examining metformin use in pregnancy have expanded. New clinical trials are underway to investigate the potential benefits of metformin use during lactation. The importance of insulin signaling in milk secretion raises the possibility that an insulin sensitizer may have an impact on lactation output. We provide new data demonstrating that metformin exposure during lactation in a mouse model causes modifications to lactation leading to programming effects in the murine neonatal pancreas.

Objective

To establish how metformin administration during lactation in a rodent model impacts maternal lactation physiology and how this in turn effects pup metabolic health.

Methods

Metformin was delivered in drinking water to C57BL/6J mice at either a high or low dose from postnatal day 1 (P1) and continued throughout lactation (Met PN group). Animals were examined for pancreatic morphology at mid‐lactation and for metabolic health during young adulthood. Mothers were also examined for mammary gland characteristics during lactation and upon weaning.

Results

Dams given a lower aqueous dose of metformin from P1 showed an indication of increased milk output through estimated milk volume experiments. Metformin exposed pups also had increased body weight during the first 3 weeks of life. In a separate set of experiments, dams given a higher dose of metformin demonstrated decreased cleaved caspase‐3 by western blotting in mammary glands taken 2 days after weaning. Pups that nursed from the mothers that received a higher dose metformin showed increased b‐cell mass at postnatal day 11 (P11). Male offspring exhibited improved glucose tolerance test (GTT) at 2 months of age and an increase in glucose stimulated insulin secretion (GSIS) in vivo. Metformin exposed offspring body weight was lower in these offspring than control pups and remained so throughout the period of the experiment.

Conclusions

These findings suggest that metformin may have an impact on lactation output at lower doses and lead to a delay in involution of the mammary gland at the time of weaning at higher doses. These effects seem to result in long‐term programming of metabolic health in the offspring. These findings could support the use of metformin during lactation to augment milk output and the potential for this exposure to have beneficial effects on offspring metabolism.

Support or Funding Information

Amendt‐Heller Award for Newborn Research 1

K08 DK102526 01A1
Assessment of circannual variation in relative weight among children in Wisconsin using electronic health records
Authors: Bhutani Surabhi , Schoeller Dale , Kloke John , Hanrahan Lawrence
Published: November 2023

Objective

Summer weight gain (June through August inclusive) has been repeatedly reported in children. This has recently led to the development and implementation of multiple interventions to address the child's summer environment. Most reports on summer weight gain are mainly based on measures of BMI at the beginning (Sept./Oct.) and end of the school season (May/June), and are the only time points used to demonstrate the success of school based obesity prevention interventions. Basing the relative weight outcome on just two measures may be risky and therefore data on the time course of this weight gain in children is necessary. Thus, the objective of this study was to investigate circannual pattern in childhood weight status.

Method

We analyzed cross‐sectional height and weight data from de‐identified electronic medical records of 225,607 children (5–17yr) collected between 2007–2012 from South Central Wisconsin. The average monthly BMI and BMI z‐score were calculated and categorized by age, sex, and minority status.

Results

Averaged across ages, the BMI z‐scores increased during the school year (Sept. – May) by 0.03±0.4 z‐score (P<0.05), but decreased from May to June by 0.08±0.4 z‐score (p<0.01) and then increased from Aug. to Sept. by 0.06±0.4 units (p<0.01). The BMI z‐scores for males were slightly higher than for females and both displayed similar and distinctive differences between May and June and averages being greater beginning in July or Aug. When categorized by race/ethnicity, the BMI z‐scores during July were lowest than those of Sept‐May for Non‐Hispanic White population. Non‐Hispanic Blacks had the lowest BMI z‐score at the beginning of the school year (Sept.) while Hispanics had the lowest BMI z‐score at the end of summer (Aug.).

Conclusion

Our analysis is consistent with summer weight gain findings from other studies showing a slightly lower BMI z‐score during the school year (Sept. to beginning of June) and higher BMI z‐score during the summer (beginning of Jun to Sept). This pattern would probably be interpreted as a successful intervention by the school followed by regression during the summer, even if there is no effect of the intervention per se. But this also raises issues about adequacy of 2 measures of z‐scores for school evaluations due to lower BMI z‐scores in summer period. We suggest taking additional measures at least in Dec. and March so that a time trend analysis can be performed. An alternate approach might be to move the assessment months to Oct and April. Moreover, a longitudinal study is required to confirm the circannual pattern we observed using cross‐sectional data.
Television food advertisement exposure and FTO genotype in relation to excess consumption in children
Authors: Gilbert‐Diamond Diane , Emond Jennifer , Lansigan Reina Kato , Rapuano Kristina , Kelley William , Heatherton Todd , Sargent James
Published: November 2023

IMPORTANCE

Exposure to food advertisements may cue overeating among children, especially those genetically predisposed to eat more in response to food cues.

OBJECTIVE

To assess how television food advertisements affect eating in the absence of hunger among children in a randomized trial. We hypothesized that the effect of food advertisements would be modified by the Fat Mass and Obesity Associated Gene (FTO) rs9939609 single nucleotide polymorphism.

DESIGN, SETTING, AND PARTICIPANTS

In this randomized experiment, 172 children aged 9–10 years old were served a standardized lunch to self‐reported satiety and then shown a children's television show embedded with either food or toy advertisements. Children were provided one food that was advertised during the show (gummy candy) and three that were not advertised (chocolate candy, cookies, chips) to consume ad libitum while watching the show. Children were genotyped for rs9939609. Additional characteristics of the child were collected via questionnaires.

EXPOSURES

Assignment to view either food or toy advertisements (7.7 minutes) embedded in a child's television show (34 minutes).

MAIN OUTCOME MEASURES

Total caloric intake during the experimental exposure (overall and by advertised vs. non‐advertised foods). Analyses assessed the outcome overall and stratified by FTO genotype.

RESULTS

Children consumed on average 440 (SD=185) kCals during lunch and 482 (SD=274) kCals during the experimental exposure. There was no main effect of experimental exposure on total snack food consumed while viewing the television show (P = 0.27); however, children who viewed food advertisements consumed an average of 48 kCals (95% CI: 10, 85; P=0.01) more of a recently advertised food than those who viewed toy advertisements. Further, there was a statistically significant interaction between genotype and food advertisement condition (P=0.02), where the difference in consumption of the recently advertised food related to food vs. toy advertisement exposure increased linearly with each additional FTO risk‐allele: −3, 59, and 125 kCals for the TT, AT, and AA genotypes, respectively.

CONCLUSIONS AND RELEVANCE

Food advertisement exposure was associated with greater caloric consumption of a recently advertised food, and this effect was modified by FTO genotype. Future research is needed to understand the neurological mechanism underlying these associations.

Support or Funding Information

This study was supported by grant R21HD076097 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NIH) (Dr. Gilbert‐Diamond); by grant R01DA022582 from the National Institute of Drug Addiction (NIH) (Heatherton); by grant R01CA077026 from the National Cancer Institute (NIH) (Sargent); by grant R01AA021347 from the National Institute of Alcohol Abuse and Alcoholism (NIH) (Sargent).