An integrative systems genetic analysis of mammalian lipid metabolism.

Dysregulation of lipid homeostasis is a precipitating event in the pathogenesis and progression of hepatosteatosis and metabolic syndrome. These conditions are highly prevalent in developed societies and currently have limited options for diagnostic and therapeutic intervention. Here, using a proteomic and lipidomic-wide systems genetic approach, we interrogated lipid regulatory networks in 107 genetically distinct mouse strains to reveal key insights into the control and network structure of mammalian lipid metabolism. These include the identification of plasma lipid signatures that predict pathological lipid abundance in the liver of mice and humans, defining subcellular localization and functionality of lipid-related proteins, and revealing functional protein and genetic variants that are predicted to modulate lipid abundance. Trans-omic analyses using these datasets facilitated the identification and validation of PSMD9 as a previously unknown lipid regulatory protein. Collectively, our study serves as a rich resource for probing mammalian lipid metabolism and provides opportunities for the discovery of therapeutic agents and biomarkers in the setting of hepatic lipotoxicity.

ACAD10 is not required for metformin's metabolic actions or for maintenance of whole-body metabolism in C57BL/6J mice.

AIM: Acyl-coenzyme A dehydrogenase family member 10 (ACAD10) is a mitochondrial protein purported to be involved in the fatty acid oxidation pathway. Metformin is the most prescribed therapy for type 2 diabetes; however, its precise mechanisms of action(s) are still being uncovered. Upregulation of ACAD10 is a requirement for metformin's ability to inhibit growth in cancer cells and extend lifespan in Caenorhabditis elegans. However, it is unknown whether ACAD10 plays a role in metformin's metabolic actions. MATERIALS AND METHODS: We assessed the role for ACAD10 on whole-body metabolism and metformin action by generating ACAD10KO mice on a C57BL/6J background via CRISPR-Cas9 technology. In-depth metabolic phenotyping was conducted in both sexes on a normal chow and high fat-high sucrose diet. RESULTS: Compared with wildtype mice, we detected no difference in body composition, energy expenditure or glucose tolerance in male or female ACAD10KO mice, on a chow diet or high-fat, high-sucrose diet (p ≥ .05). Hepatic mitochondrial function and insulin signalling was not different between genotypes under basal or insulin-stimulated conditions (p ≥ .05). Glucose excursions following acute administration of metformin before a glucose tolerance test were not different between genotypes nor was body composition or energy expenditure altered after 4 weeks of daily metformin treatment (p ≥ .05). Despite the lack of a metabolic phenotype, liver lipidomic analysis suggests ACAD10 depletion influences the abundance of specific ceramide species containing very long chain fatty acids, while metformin treatment altered clusters of cholesterol ester, plasmalogen, phosphatidylcholine and ceramide species. CONCLUSIONS: Loss of ACAD10 does not alter whole-body metabolism or impact the acute or chronic metabolic actions of metformin in this model.

Apo AI Nanoparticles Delivered Post Myocardial Infarction Moderate Inflammation.

RATIONALE: Decades of research have examined immune-modulatory strategies to protect the heart after an acute myocardial infarction and prevent progression to heart failure but have failed to translate to clinical benefit. OBJECTIVE: To determine anti-inflammatory actions of n-apo AI (Apo AI nanoparticles) that contribute to cardiac tissue recovery after myocardial infarction. METHODS AND RESULTS: Using a preclinical mouse model of myocardial infarction, we demonstrate that a single intravenous bolus of n-apo AI (CSL111, 80 mg/kg) delivered immediately after reperfusion reduced the systemic and cardiac inflammatory response. N-apo AI treatment lowered the number of circulating leukocytes by 30±7% and their recruitment into the ischemic heart by 25±10% (all P<5.0×10-2). This was associated with a reduction in plasma levels of the clinical biomarker of cardiac injury, cardiac troponin-I, by 52±17% (P=1.01×10-2). N-apo AI reduced the cardiac expression of chemokines that attract neutrophils and monocytes by 60% to 80% and lowered surface expression of integrin CD11b on monocytes by 20±5% (all P<5.0×10-2). Fluorescently labeled n-apo AI entered the infarct and peri-infarct regions and colocalized with cardiomyocytes undergoing apoptosis and with leukocytes. We further demonstrate that n-apo AI binds to neutrophils and monocytes, with preferential binding to the proinflammatory monocyte subtype and partially via SR-BI (scavenger receptor BI). In patients with type 2 diabetes, we also observed that intravenous infusion of the same n-apo AI (CSL111, 80 mg/kg) similarly reduced the level of circulating leukocytes by 12±5% (all P<5.0×10-2). CONCLUSIONS: A single intravenous bolus of n-apo AI delivered immediately post-myocardial infarction reduced the systemic and cardiac inflammatory response through direct actions on both the ischemic myocardium and leukocytes. These data highlight the anti-inflammatory effects of n-apo AI and provide preclinical support for investigation of its use for management of acute coronary syndromes in the setting of primary percutaneous coronary interventions.

Genome-Wide Association Study Identifies a Functional SIDT2 Variant Associated With HDL-C (High-Density Lipoprotein Cholesterol) Levels and Premature Coronary Artery Disease.

Objective: Low HDL-C (high-density lipoprotein cholesterol) is the most frequent dyslipidemia in Mexicans, but few studies have examined the underlying genetic basis. Our purpose was to identify genetic variants associated with HDL-C levels and cardiovascular risk in the Mexican population. Approach and Results: A genome-wide association studies for HDL-C levels in 2335 Mexicans, identified four loci associated with genome-wide significance: CETP, ABCA1, LIPC, and SIDT2. The SIDT2 missense Val636Ile variant was associated with HDL-C levels and was replicated in 3 independent cohorts (P=5.9×10−18 in the conjoint analysis). The SIDT2/Val636Ile variant is more frequent in Native American and derived populations than in other ethnic groups. This variant was also associated with increased ApoA1 and glycerophospholipid serum levels, decreased LDL-C (low-density lipoprotein cholesterol) and ApoB levels, and a lower risk of premature CAD. Because SIDT2 was previously identified as a protein involved in sterol transport, we tested whether the SIDT2/Ile636 protein affected this function using an in vitro site-directed mutagenesis approach. The SIDT2/Ile636 protein showed increased uptake of the cholesterol analog dehydroergosterol, suggesting this variant affects function. Finally, liver transcriptome data from humans and the Hybrid Mouse Diversity Panel are consistent with the involvement of SIDT2 in lipid and lipoprotein metabolism. Conclusions: This is the first genome-wide association study for HDL-C levels seeking associations with coronary artery disease in the Mexican population. Our findings provide new insight into the genetic architecture of HDL-C and highlight SIDT2 as a new player in cholesterol and lipoprotein metabolism in humans.

Sex differences in white adipose tissue expansion: emerging molecular mechanisms.

The escalating prevalence of individuals becoming overweight and obese is a rapidly rising global health problem, placing an enormous burden on health and economic systems worldwide. Whilst obesity has well described lifestyle drivers, there is also a significant and poorly understood component that is regulated by genetics. Furthermore, there is clear evidence for sexual dimorphism in obesity, where overall risk, degree, subtype and potential complications arising from obesity all differ between males and females. The molecular mechanisms that dictate these sex differences remain mostly uncharacterised. Many studies have demonstrated that this dimorphism is unable to be solely explained by changes in hormones and their nuclear receptors alone, and instead manifests from coordinated and highly regulated gene networks, both during development and throughout life. As we acquire more knowledge in this area from approaches such as large-scale genomic association studies, the more we appreciate the true complexity and heterogeneity of obesity. Nevertheless, over the past two decades, researchers have made enormous progress in this field, and some consistent and robust mechanisms continue to be established. In this review, we will discuss some of the proposed mechanisms underlying sexual dimorphism in obesity, and discuss some of the key regulators that influence this phenomenon.

Estrogen receptor α protects pancreatic ß-cells from apoptosis by preserving mitochondrial function and suppressing endoplasmic reticulum stress.

Estrogen receptor α (ERα) action plays an important role in pancreatic ß-cell function and survival; thus, it is considered a potential therapeutic target for the treatment of type 2 diabetes in women. However, the mechanisms underlying the protective effects of ERα remain unclear. Because ERα regulates mitochondrial metabolism in other cell types, we hypothesized that ERα may act to preserve insulin secretion and promote ß-cell survival by regulating mitochondrial-endoplasmic reticulum (EndoRetic) function. We tested this hypothesis using pancreatic islet-specific ERα knockout (PERαKO) mice and Min6 ß-cells in culture with Esr1 knockdown (KD). We found that Esr1-KD promoted reactive oxygen species production that associated with reduced fission/fusion dynamics and impaired mitophagy. Electron microscopy showed mitochondrial enlargement and a pro-fusion phenotype. Mitochondrial cristae and endoplasmic reticulum were dilated in Esr1-KD compared with ERα replete Min6 ß-cells. Increased expression of Oma1 and Chop was paralleled by increased oxygen consumption and apoptosis susceptibility in ERα-KD cells. In contrast, ERα overexpression and ligand activation reduced both Chop and Oma1 expression, likely by ERα binding to consensus estrogen-response element sites in the Oma1 and Chop promoters. Together, our findings suggest that ERα promotes ß-cell survival and insulin secretion through maintenance of mitochondrial fission/fusion-mitophagy dynamics and EndoRetic function, in part by Oma1 and Chop repression.

The E3 ligase MARCH5 is a PPARγ target gene that regulates mitochondria and metabolism in adipocytes.

Mitochondrial dynamics refers to the constant remodeling of mitochondrial populations by multiple cellular pathways that help maintain mitochondrial health and function. Disruptions in mitochondrial dynamics often lead to mitochondrial dysfunction, which is frequently associated with disease in rodents and humans. Consistent with this, obesity is associated with reduced mitochondrial function in white adipose tissue, partly via alterations in mitochondrial dynamics. Several proteins, including the E3 ubiquitin ligase membrane-associated RING-CH-type finger 5 (MARCH5), are known to regulate mitochondrial dynamics; however, the role of these proteins in adipocytes has been poorly studied. Here, we show that MARCH5 is regulated by peroxisome proliferator-activated receptor-γ (PPARγ) during adipogenesis and is correlated with fat mass across a panel of genetically diverse mouse strains, in ob/ob mice, and in humans. Furthermore, manipulation of MARCH5 expression in vitro and in vivo alters mitochondrial function, affects cellular metabolism, and leads to differential regulation of several metabolic genes. Thus our data demonstrate an association between mitochondrial dynamics and metabolism that defines MARCH5 as a critical link between these interconnected pathways.

Skeletal muscle-specific overexpression of heat shock protein 72 improves skeletal muscle insulin-stimulated glucose uptake but does not alter whole body metabolism.

AIMS: The induction of heat shock protein 72 (Hsp72) via heating, genetic manipulation or pharmacological activation is metabolically protective in the setting of obesity-induced insulin resistance across mammalian species. In this study, we set out to determine whether the overexpression of Hsp72, specifically in skeletal muscle, can protect against high-fat diet (HFD)-induced obesity and insulin resistance. MATERIALS AND METHODS: An Adeno-Associated Viral vector (AAV), designed to overexpress Hsp72 in skeletal muscle only, was used to study the effects of increasing Hsp72 levels on various metabolic parameters. Two studies were conducted, the first with direct intramuscular (IM) injection of the AAV:Hsp72 into the tibialis anterior hind-limb muscle and the second with a systemic injection to enable body-wide skeletal muscle transduction. RESULTS: IM injection of the AAV:Hsp72 significantly improved skeletal muscle insulin-stimulated glucose clearance in treated hind-limb muscles, as compared with untreated muscles of the contralateral leg when mice were fed an HFD. Despite this finding, systemic administration of AAV:Hsp72 did not improve body composition parameters such as body weight, fat mass or percentage body fat, nor did it lead to an improvement in fasting glucose levels or glucose tolerance. Furthermore, no differences were observed for other metabolic parameters such as whole-body oxygen consumption, energy expenditure or physical activity levels. CONCLUSIONS: At the levels of Hsp72 over-expression reported herein, skeletal muscle-specific Hsp72 overexpression via IM injection has the capacity to increase insulin-stimulated glucose clearance in this muscle. However, upon systemic injection, which results in lower muscle Hsp72 overexpression, no beneficial effects on whole-body metabolism are observed.

Health Conditions: Effect on Function, Health-Related Quality of Life, and Life Satisfaction After Traumatic Spinal Cord Injury. A Prospective Observational Registry Cohort Study.

OBJECTIVE: To analyze relations among injury, demographic, and environmental factors on function, health-related quality of life (HRQoL), and life satisfaction in individuals with traumatic spinal cord injury (SCI). DESIGN: Prospective observational registry cohort study. SETTING: Specialized acute and rehabilitation SCI centers. PARTICIPANTS: Participants (N=340) from the Rick Hansen Spinal Cord Injury Registry (RHSCIR) who were prospectively recruited from 2004 to 2014 were included. The model cohort participants were 79.1% men, with a mean age of 41.6±17.3 years. Of the participants, 34.7% were motor/sensory complete (ASIA Impairment Scale [AIS] grade A). INTERVENTIONS: None. MAIN OUTCOME MEASURES: Path analysis was used to determine relations among SCI severity (AIS grade and anatomic level [cervical/thoracolumbar]), age at injury, education, number of health conditions, functional independence (FIM motor score), HRQoL (Medical Outcomes Study 36-Item Short-Form Health Survey [Version 2] Physical Component Score [PCS] and Mental Component Score [MCS]), and life satisfaction (Life Satisfaction-11 [LiSat-11]). Model fit was assessed using recommended published indices. RESULTS: Goodness of fit of the model was supported by all indices, indicating the model results closely matched the RHSCIR data. Higher age, higher severity injuries, cervical injuries, and more health conditions negatively affected FIM motor score, whereas employment had a positive effect. Higher age, less education, more severe injuries (AIS grades A-C), and more health conditions negatively correlated with PCS (worse physical health). More health conditions were negatively correlated with a lower MCS (worse mental health), however were positively associated with reduced function. Being married and having higher function positively affected Lisat-11, but more health conditions had a negative effect. CONCLUSIONS: Complex interactions and enduring effects of health conditions after SCI have a negative effect on function, HRQoL, and life satisfaction. Modeling relations among these types of concepts will inform clinicians how to positively effect outcomes after SCI (eg, development of screening tools and protocols for managing individuals with traumatic SCI who have multiple health conditions).

The Role of Skeletal Muscle Estrogen Receptors in Metabolic Homeostasis and Insulin Sensitivity.

Women in the modern era are challenged with facing menopausal symptoms as well as heightened disease risk associated with increasing adiposity and metabolic dysfunction for up to three decades of life. Treatment strategies to combat metabolic dysfunction and associated pathologies have been hampered by our lack of understanding regarding the biological causes of these clinical conditions and our incomplete understanding regarding the effects of estrogens and the tissue-specific functions and molecular actions of its receptors. In this chapter we provide evidence supporting a critical and protective role for skeletal muscle estrogen receptor α in the maintenance of metabolic homeostasis and insulin sensitivity. Studies identifying the critical ER-regulated pathways essential for disease prevention will lay the important foundation for the rational design of novel therapeutic strategies to improve the health of women while limiting secondary complications that have plagued traditional hormone replacement interventions.

Improving spine surgical access, appropriateness and efficiency in metropolitan, urban and rural settings.

BACKGROUND: The Inter-professional Spine Assessment and Education Clinics (ISAEC) were developed to improve primary care assessment, education and management of patients with persistent or recurrent low back pain-related symptoms. This study aims to determine the effect of ISAEC on access for surgical assessment, referral appropriateness and efficiency for patients meeting a priori referral criteria in rural, urban and metropolitan settings. METHODS: We conducted a retrospective review of prospective data from networked ISAEC clinics in Thunder Bay, Hamilton and Toronto, Ontario. For patients meeting surgical referral criteria, wait times for surgical assessment, surgical referral-related magnetic resonance imaging (MRI) scans and appropriateness of referral were recorded. RESULTS: Overall 422 patients, representing 10% of all ISAEC patients in the study period, were referred for surgical assessment. The average wait times for surgical assessment were 5.4, 4.3 and 2.2 weeks at the metropolitan, urban and rural centres, respectively. Referral MRI usage for the group decreased by 31%. Of the patients referred for formal surgical assessment, 80% had leg-dominant pain and 96% were deemed appropriate surgical referrals. CONCLUSION: Contrary to geographic concentration of health care resources in metropolitan settings, the greatest decrease in wait times was achieved in the rural setting. A networked, shared-cared model of care for patients with low back pain-related symptoms significantly improved access for surgical assessment despite varying geographic practice settings and barriers. The greatest reductions were noted in the rural setting. In addition, significant improvements in referral appropriateness and efficiency were achieved compared with historical reports across all sites.

CONTEXTE: Les cliniques interprofessionnelles d'évaluation de la colonne vertébrale et d'éducation (Inter-professional Spine Assessment and Education Clinics [ISAEC]) ont été mises sur pied pour améliorer les soins primaires d'évaluation, d'éducation et de prise en charge des patients atteints de symptômes persistants ou récurrents de lombalgie. Cette étude a pour but d'évaluer l'effet des ISAEC sur l'accès à une évaluation chirurgicale et sur la pertinence et l'efficacité de la référence des patients en milieux ruraux, urbains et métropolitains répondant a priori aux critères de référence. MÉTHODES: Nous avons mené une étude rétrospective de données prospectives issues de cliniques du réseau des ISAEC situées à Thunder Bay, à Hamilton et à Toronto, en Ontario. Nous avons retenu pour l'étude les patients répondant aux critères de référence en chirurgie; pour chacun de ces patients, nous avons consigné le temps d'attente pour obtenir une évaluation chirurgicale, les images obtenues par résonance magnétique (IRM) aux fins de référence et la pertinence de la référence. RÉSULTATS: Au total, 422 patients, soit 10 % des patients des ISAEC au cours de la période étudiée, ont été dirigés en évaluation chirurgicale. Les temps d'attente moyens pour obtenir une évaluation chirurgicale étaient de 5,4 semaines, de 4,3 semaines et de 2,2 semaines dans les centres métropolitains, urbains et ruraux, respectivement. Le recours à l'IRM aux fins de référence a diminué de 31 % par rapport à la situation initiale. Parmi les patients référés en évaluation chirurgicale formelle, 80 % présentaient une douleur principalement localisée dans les jambes. La référence de 96 % des patients a été jugée adéquate. CONCLUSION: Même si les ressources en soins de santé sont concentrées en milieu métropolitain, c'est le milieu rural qui a connu la plus grande baisse du temps d'attente. La mise sur pied d'un modèle de soins partagés en réseau pour les patients aux prises avec des symptômes de lombalgie a amélioré l'accès aux évaluations chirurgicales de façon significative, malgré la variété géographique des milieux de pratique et les divers obstacles rencontrés. Les baisses les plus importantes ont été observées en milieu rural. De plus, des améliorations significatives de la pertinence et de l'efficacité des références ont été observées lors de la comparaison avec les rapports antérieurs, pour tous les sites de l'étude.

Estrogen receptor (ER)α-regulated lipocalin 2 expression in adipose tissue links obesity with breast cancer progression.

Obesity is associated with increased breast cancer (BrCA) incidence. Considering that inactivation of estrogen receptor (ER)α promotes obesity and metabolic dysfunction in women and female mice, understanding the mechanisms and tissue-specific sites of ERα action to combat metabolic-related disease, including BrCA, is of clinical importance. To study the role of ERα in adipose tissue we generated fat-specific ERα knock-out (FERKO) mice. Herein we show that ERα deletion increased adipocyte size, fat pad weight, and tissue expression and circulating levels of the secreted glycoprotein, lipocalin 2 (Lcn2), an adipokine previously associated with BrCA development. Chromatin immunoprecipitation and luciferase reporter studies showed that ERα binds the Lcn2 promoter to repress its expression. Because adipocytes constitute an important cell type of the breast microenvironment, we examined the impact of adipocyte ERα deletion on cancer cell behavior. Conditioned medium from ERα-null adipocytes and medium containing pure Lcn2 increased proliferation and migration of a subset of BrCA cells in culture. The proliferative and promigratory effects of ERα-deficient adipocyte-conditioned medium on BrCA cells was reversed by Lcn2 deletion. BrCA cell responsiveness to exogenous Lcn2 was heightened in cell types where endogenous Lcn2 expression was minimal, but components of the Lcn2 signaling pathway were enriched, i.e. SLC22A17 and 3-hydroxybutyrate dehydrogenase (BDH2). In breast tumor biopsies from women diagnosed with BrCA we found that BDH2 expression was positively associated with adiposity and circulating Lcn2 levels. Collectively these data suggest that reduction of ERα expression in adipose tissue promotes adiposity and is linked with the progression and severity of BrCA via increased adipocyte-specific Lcn2 production and enhanced tumor cell Lcn2 sensitivity.

Long non-coding RNAs (lncRNAs) in skeletal and cardiac muscle: potential therapeutic and diagnostic targets?

The recent discovery that thousands of RNAs are transcribed by the cell but are never translated into protein, highlights a significant void in our current understanding of how transcriptional networks regulate cellular function. This is particularly astounding when we consider that over 75% of the human genome is transcribed into RNA, but only approximately 2% of RNA is translated into known proteins. This raises the question as to what function the other so-called 'non-coding RNAs' (ncRNAs) are performing in the cell. Over the last decade, an enormous amount of research has identified several classes of ncRNAs, predominantly short ncRNAs (<200 nt) that have been confirmed to have functional significance. Recent advances in sequencing technology and bioinformatics have also allowed for the identification of a novel class of ncRNAs, termed long ncRNA (lncRNA) (>200 nt). Several studies have recently shown that long non-coding RNAs (lncRNAs) are associated with tissue development and disease, particularly in cell types that undergo differentiation such as stem cells, cancer cells and striated muscle (skeletal/cardiac). Therefore, understanding the function of these lncRNAs and designing strategies to detect and manipulate them, may present novel therapeutic and diagnostic opportunities. This review will explore the current literature on lncRNAs in skeletal and cardiac muscle and discuss their recent implication in development and disease. Lastly, we will also explore the possibility of using lncRNAs as therapeutic and diagnostic tools and discuss the opportunities and potential shortcomings to these applications.

Effect of older age on treatment decisions and outcomes among patients with traumatic spinal cord injury.

BACKGROUND: Older people are at increased risk of traumatic spinal cord injury from falls. We evaluated the impact of older age (≥ 70 yr) on treatment decisions and outcomes. METHODS: We identified patients with traumatic spinal cord injury for whom consent and detailed data were available from among patients recruited (2004-2013) at any of the 31 acute care and rehabilitation hospitals participating in the Rick Hansen Spinal Cord Injury Registry. Patients were assessed by age group (< 70 v. ≥ 70 yr). The primary outcome was the rate of acute surgical treatment. We used bivariate and multivariate regression models to assess patient and injury-related factors associated with receiving surgical treatment and with the timing of surgery after arrival to a participating centre. RESULTS: Of the 1440 patients included in our study cohort, 167 (11.6%) were 70 years or older at the time of injury. Older patients were more likely than younger patients to be injured by falling (83.1% v. 37.4%; p < 0.001), to have a cervical injury (78.0% v. 61.6%; p = 0.001), to have less severe injuries on admission (American Spinal Injury Association Impairment Scale grade C or D: 70.5% v. 46.9%; p < 0.001), to have a longer stay in an acute care hospital (median 35 v. 28 d; p < 0.005) and to have a higher in-hospital mortality (4.2% v. 0.6%; p < 0.001). Multivariate analysis did not show that age of 70 years or more at injury was associated with a decreased likelihood of surgical treatment (adjusted odds ratio [OR] 0.48, 95% confidence interval [CI] 0.22-1.07). An unplanned sensitivity analysis with different age thresholds showed that a threshold of 65 years was associated with a decreased chance of surgical treatment (OR 0.39, 95% CI 0.19-0.80). Older patients who underwent surgical treatment had a significantly longer wait time from admission to surgery than younger patients (37 v. 19 h; p < 0.001). INTERPRETATION: We found chronological age to be a factor influencing treatment decisions but not at the 70-year age threshold that we had hypothesized. Older patients waited longer for surgery and had a substantially higher in-hospital mortality despite having less severe injuries than younger patients. Further research into the link between treatment delays and outcomes among older patients could inform surgical guideline development.

Intrawound vancomycin to prevent infections after spine surgery: a systematic review and meta-analysis.

PURPOSE: Post-operative spine surgical site infections are associated with substantial morbidity, mortality, and economic burden. Intrawound vancomycin may prevent infections after spine surgery, but recent studies have reported conflicting results. The objectives of this systematic review and meta-analysis were to determine: (1) In patients undergoing spine surgery, does the application of intrawound vancomycin lead to reduced rates of post-operative surgical site infections? (2) Are there differences in the estimates of effect between observational studies and randomized trials? (3) What adverse events are reported in the literature? METHODS: All published comparative studies of intrawound vancomycin in spine surgery were included. Two reviewers independently screened eligible articles and assessed study quality. Observational studies and randomized trials were pooled separately using a random-effects model. RESULTS: Eight observational studies and one randomized controlled trial met the inclusion criteria. Across observational studies, the odds of infection with intrawound vancomycin was 0.19 times the odds of infection without intrawound vancomycin (95 % CI 0.08-0.47, p = 0.0003, I (2) = 52 %). The single randomized controlled trial produced a conflicting result (OR 0.96, 95 % CI 0.34-2.66, p = 0.93). There were no adverse events attributable to intrawound vancomycin. The quality of the evidence was low or very low. CONCLUSIONS: There is a lack of high-quality evidence to inform the use of intrawound vancomycin in spine surgery. Surgeons should be cautious before widely adopting this intervention and should be vigilant in monitoring for adverse effects. Further investigation with additional randomized controlled trials is justified.

Myeloid-specific estrogen receptor alpha deficiency impairs metabolic homeostasis and accelerates atherosclerotic lesion development.

ERα is expressed in macrophages and other immune cells known to exert dramatic effects on glucose homeostasis. We investigated the impact of ERα expression on macrophage function to determine whether hematopoietic or myeloid-specific ERα deletion manifests obesity-induced insulin resistance in mice. Indeed, altered plasma adipokine and cytokine levels, glucose intolerance, insulin resistance, and increased adipose tissue mass were observed in animals harboring a hematopoietic or myeloid-specific deletion of ERα. A similar obese phenotype and increased atherosclerotic lesion area was displayed in LDL receptor-KO mice transplanted with ERα(-/-) bone marrow. In isolated macrophages, ERα was necessary for repression of inflammation, maintenance of oxidative metabolism, IL-4-mediated induction of alternative activation, full phagocytic capacity in response to LPS, and oxidized LDL-induced expression of ApoE and Abca1. Furthermore, we identified ERα as a direct regulator of macrophage transglutaminase 2 expression, a multifunctional atheroprotective enzyme. Our findings suggest that diminished ERα expression in hematopoietic/myeloid cells promotes aspects of the metabolic syndrome and accelerates atherosclerosis in female mice.

Hepatic retinol dehydrogenase 11 dampens stress associated with the maintenance of cellular cholesterol levels.

OBJECTIVE: Dysregulation of hepatic cholesterol metabolism can contribute to elevated circulating cholesterol levels, which is a significant risk factor for cardiovascular disease. Cholesterol homeostasis in mammalian cells is tightly regulated by an integrated network of transcriptional and post-transcriptional signalling pathways. Whilst prior studies have identified many of the central regulators of these pathways, the extended supporting networks remain to be fully elucidated. METHODS: Here, we leveraged an integrated discovery platform, combining multi-omics data from 107 strains of mice to investigate these supporting networks. We identified retinol dehydrogenase 11 (RDH11; also known as SCALD) as a novel protein associated with cholesterol metabolism. Prior studies have suggested that RDH11 may be regulated by alterations in cellular cholesterol status, but its specific roles in this pathway are mostly unknown. RESULTS: Here, we show that mice fed a Western diet (high fat, high cholesterol) exhibited a significant reduction in hepatic Rdh11 mRNA expression. Conversely, mice treated with a statin (3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) inhibitor) exhibited a 2-fold increase in hepatic Rdh11 mRNA expression. Studies in human and mouse hepatocytes demonstrated that RDH11 expression was regulated by altered cellular cholesterol conditions in a manner consistent with SREBP2 target genes HMGCR and LDLR. Modulation of RDH11 in vitro and in vivo demonstrated modulation of pathways associated with cholesterol metabolism, inflammation and cellular stress. Finally, RDH11 silencing in mouse liver was associated with a reduction in hepatic cardiolipin abundance and a concomitant reduction in the abundance of proteins of the mitochondrial electron transport chain. CONCLUSION: Taken together, these findings suggest that RDH11 likely plays a role in protecting cells against the cellular toxicity that can arise as a by-product of endogenous cellular cholesterol synthesis.

A gene therapy targeting medium-chain acyl-CoA dehydrogenase (MCAD) did not protect against diabetes-induced cardiac pathology.

Diabetic cardiomyopathy describes heart disease in patients with diabetes who have no other cardiac conditions but have a higher risk of developing heart failure. Specific therapies to treat the diabetic heart are limited. A key mechanism involved in the progression of diabetic cardiomyopathy is dysregulation of cardiac energy metabolism. The aim of this study was to determine if increasing the expression of medium-chain acyl-coenzyme A dehydrogenase (MCAD; encoded by Acadm), a key regulator of fatty acid oxidation, could improve the function of the diabetic heart. Male mice were administered streptozotocin to induce diabetes, which led to diastolic dysfunction 8 weeks post-injection. Mice then received cardiac-selective adeno-associated viral vectors encoding MCAD (rAAV6:MCAD) or control AAV and were followed for 8 weeks. In the non-diabetic heart, rAAV6:MCAD increased MCAD expression (mRNA and protein) and increased Acadl and Acadvl, but an increase in MCAD enzyme activity was not detectable. rAAV6:MCAD delivery in the diabetic heart increased MCAD mRNA expression but did not significantly increase protein, activity, or improve diabetes-induced cardiac pathology or molecular metabolic and lipid markers. The uptake of AAV viral vectors was reduced in the diabetic versus non-diabetic heart, which may have implications for the translation of AAV therapies into the clinic. KEY MESSAGES: The effects of increasing MCAD in the diabetic heart are unknown. Delivery of rAAV6:MCAD increased MCAD mRNA and protein, but not enzyme activity, in the non-diabetic heart. Independent of MCAD enzyme activity, rAAV6:MCAD increased Acadl and Acadvl in the non-diabetic heart. Increasing MCAD cardiac gene expression alone was not sufficient to protect against diabetes-induced cardiac pathology. AAV transduction efficiency was reduced in the diabetic heart, which has clinical implications.

Decorin, an exercise-induced secretory protein, is associated with improved prognosis in breast cancer patients but does not mediate anti-tumorigenic tissue crosstalk in mice.

BACKGROUND: Regular exercise can reduce incidence and progression of breast cancer, but the mechanisms for such effects are not fully understood. METHODS: We used a variety of rodent and human experimental model systems to determine whether exercise training can reduce tumor burden in breast cancer and to identify mechanism associated with any exercise training effects on tumor burden. RESULTS: We show that voluntary wheel running slows tumor development in the mammary specific polyomavirus middle T antigen overexpression (MMTV-PyMT) mouse model of breast cancer but only when mice are not housed alone. We identify the proteoglycan decorin as a contraction-induced secretory factor that systemically increases in patients with breast cancer immediately following exercise. Moreover, high expression of decorin in tumors is associated with improved prognosis in patients, while treatment of breast cancer cells in vitro with decorin reduces cell proliferation. Notwithstanding, when we overexpressed decorin in murine muscle or injected recombinant decorin systemically into mouse models of breast cancer, elevated plasma decorin concentrations did not result in higher tumor decorin levels and tumor burden was not improved. CONCLUSION: Exercise training is anti-tumorigenic in a mouse model of luminal breast cancer, but the effect is abrogated by social isolation. The proteoglycan decorin is an exercise-induced secretory protein, and tumor decorin levels are positively associated with improved prognosis in patients. The hypothesis that elevated plasma decorin is a mechanism by which exercise training improves breast cancer progression in humans is not, however, supported by our pre-clinical data since elevated circulating decorin did not increase tumor decorin levels in these models.

ERα regulates lipid metabolism in bone through ATGL and perilipin.

A decrease in bone mineral density during menopause is accompanied by an increase in adipocytes in the bone marrow space. Ovariectomy also leads to accumulation of fat in the bone marrow. Herein we show increased lipid accumulation in bone marrow from estrogen receptor alpha (ERα) knockout (ERαKO) mice compared to wild-type (WT) mice or estrogen receptor beta (ERß) knockout (ERßKO) mice. Similarly, bone marrow cells from ERαKO mice differentiated to adipocytes in culture also have increased lipid accumulation compared to cells from WT mice or ERßKO mice. Analysis of individual adipocytes shows that WT mice have fewer, but larger, lipid droplets per cell than adipocytes from ERαKO or ERßKO animals. Furthermore, higher levels of adipose triglyceride lipase (ATGL) protein in WT adipocytes correlate with increased lipolysis and fewer lipid droplets per cell and treatment with 17ß-estradiol (E2) potentiates this response. In contrast, cells from ERαKO mice display higher perilipin protein levels, promoting lipogenesis. Together these results demonstrate that E2 signals via ERα to regulate lipid droplet size and total lipid accumulation in the bone marrow space in vivo.