Inconclusive decisions and error rates in forensic science

In recent years, there has been discussion and controversy relating to the treatment of inconclusive decisions in forensic feature comparison disciplines when considering the reliability of examination methods and results. In this article, we offer a brief review of the various viewpoints and suggestions that have been recently put forth, followed by a solution that we believe addresses the treatment of inconclusive decisions. We consider the issues in the context of method conformance and method performance as two distinct concepts, both of which are necessary for the determination of reliability. Method conformance relates to an assessment of whether the outcome of a method is the result of the analyst's adherence to the procedures that define the method. Method performance reflects the capacity of a method to discriminate between different propositions of interest (e.g., mated and non-mated comparisons). We then discuss implications of these issues for the forensic science community.

The anti-inflammatory agent 5-ASA reduces the level of specific tsRNAs in sperm cells of high-fat fed C57BL/6J mouse sires and improves glucose tolerance in female offspring

INTRODUCTION

The prevalence of obesity and associated comorbidities have increased to epidemic proportions globally. Paternal obesity is an independent risk factor for developing obesity and type 2 diabetes in the following generation, and growing evidence suggests epigenetic inheritance as a mechanism for this predisposition. How and why obesity induces epigenetic changes in sperm cells remain to be clarified in detail. Yet, recent studies show that alterations in sperm content of transfer RNA-derived small RNAs (tsRNAs) can transmit the effects of paternal obesity to offspring. Obesity is closely associated with low-grade chronic inflammation. Thus, we evaluated whether the anti-inflammatory agent 5-aminosalicylic acid (5-ASA) could intervene in the transmission of epigenetic inheritance of paternal obesity by reducing the inflammatory state in obese fathers.

METHODS

Male C57BL/6JBomTac mice were either fed a high-fat diet or a high-fat diet with 5-ASA for ten weeks before mating. The offspring metabolic phenotype was evaluated, and spermatozoa from sires were isolated for assessment of specific tsRNAs levels.

RESULTS

5-ASA intervention reduced the levels of Glu-CTC tsRNAs in sperm cells and improved glucose tolerance in female offspring fed a chow diet. Paternal high-fat diet-induced obesity per se had only a moderate impact on the metabolic phenotype of both male and female offspring in our setting.

CONCLUSION

The results indicate that the low-grade inflammatory response associated with obesity may be an important factor in epigenetic inheritance of paternal obesity.

Development of video tutorials to help parents manage children with acute illnesses using a modified Delphi method

AIM

Children often fall sick, which causes concern among parents. Online health information can be confusing and difficult to understand. We aimed to produce simple, informative video tutorials on the symptoms ill children present.

METHODS

We used a modified Delphi method to produce video tutorials on the symptoms fever, vomiting & diarrhea, abdominal pain, breathing difficulties, sore throat, red eyes, earache, and rash. We identified the most common symptoms in acutely ill children. During the first consensus round, experts rated statements on out-of-hospital management from existing health information. Video tutorials were produced from statements rated to be included. Second consensus involved video showings and editing. Two videos were evaluated in focus groups by parents.

RESULTS

During the first round, experts rated median 79 (40-154) statements for each symptom. Panels consisted of median seven (6-11) experts, primarily. Panels reached consensus on inclusion, neutral, or exclusion in 83% of statements. Second round led to adjustments to the videos and final approval by experts. Most parents evaluated the videos as "informative, easy to understand, and calming".

CONCLUSION

We produced video tutorials on the common symptoms ill children present using a modified Delphi method. Feedback from parents in focus groups was positive.

P10.12.A CDK12/CDK13 inhibition disrupts a transcriptional program critical for glioblastoma survival

Background

Glioblastoma multiforme (GBM) is the most prevalent and aggressive malignant tumor of the central nervous system. With a median survival of only one year, GBM patients have a particularly poor prognosis, highlighting a clear need for novel therapeutic strategies to target this disease. Transcriptional cyclin-dependent kinases (CDK), which phosphorylate key residues of RNA polymerase II (RNAPII) C-terminal domain (CTD), play a major role in sustaining aberrant transcriptional programs that are key to development and maintenance of cancer cells.

Material and Methods

We used pharmacological inhibition and genetic ablation to study effects of CDK12/CDK13 depletion on the proliferatory and migratory capacity of GBM cells and mouse xenografts. SLAM-seq, CUT&RUN and cell cycle assays were used to study the mechanistic effects of CDK12/CDK13 depletion in GBM cells.

Results

CDK12/CDK13 depletion markedly reduced the proliferatory and migratory capacity of GBM cells, as well as in vivo growth. CDK12/CDK13 inhibition potentiated existing chemotherapeutic treatments. Mechanistically, inhibition of CDK12/CDK13 leads to a genome-wide abrogation of RNAPII CTD phosphorylation, which in turn disrupts transcription and cell cycle progression in GBM cells.

Conclusion

These results provide proof-of-concept for the potential of CDK12 and CDK13 as therapeutic targets for GBM.

Lot variation and inter-device differences contribute to poor analytical performance of the DCA Vantage™ HbA1c POCT instrument in a true clinical setting

OBJECTIVES

The glycated haemoglobin fraction A_1c (HbA_1c) is widely used in the management of diabetes mellitus, and the Siemens DCA Vantage™ point-of-care testing (POCT) instrument offers rapid HbA_1c results even far from a clinical laboratory. However, the analytical performance has been questioned, and not much is known about effects of changing reagent lot, instrument and operator. We therefore compared the analytical performance of the DCA Vantage™ with established routine methods (Tosoh G8/G11 ion exchange HPLC) in a true clinical setting at two Danish hospitals.

METHODS

We extracted all routine clinical HbA_1c results incidentally drawn from the same patient within 48 h (n=960 pairs) and evaluated the effect of reagent lot, operator and instrument. We also performed a prospective method comparison in our diabetes out-patient clinic (n=97).

RESULTS

The critical difference (CD) between two POCT results varied between 5.14 and 6.61 mmol/mol (0.47-0.55%), and the analytical imprecision of the DCA Vantage™ (CV_A) was >3%. Significant effect of reagent lot and inter-instrument differences were found, whereas no effect of operator was seen.

CONCLUSIONS

The DCA Vantage™ HbA_1c analysis does not fulfil the prevailing analytical performance specifications, but rigorous validation of new reagent lots and continuous recalibration of instruments may potentially improve the precision substantially. Our findings, therefore, clearly emphasise the necessity of a close collaboration between clinicians and laboratory professionals in the POCT field. Finally, POCT HbA_1c results should always be interpreted together with other measures of glycaemic control to avoid inappropriate change of patient treatments due to measurement uncertainty.

Dental professionals' perspectives working with Aboriginal children in Western Australia: a qualitative study

BACKGROUND

The disproportionate burden of oral disease in Aboriginal children and the issues in accessing mainstream dental services are well documented. Yet little is known about dental professionals' perspectives in providing oral care for Aboriginal children. This paper presents findings from a study exploring such perspectives.

METHODS

Semi-structured interviews were carried out in Western Australia following purposive sampling of non-Aboriginal dentists, dental clinic assistants (dental nurses) and oral health therapists/dental hygienists. Interviews were recorded, transcribed and analysed guided by grounded theory for key themes related to the topic.

RESULTS

Findings included a service delivery model sometimes unresponsive to Aboriginal families' needs; dental professionals' limited education and training to work with confidence and cultural sensitivity with Aboriginal patients and socioeconomic influences on Aboriginal children's poor oral health considered outside dental professionals' remit of care.

DISCUSSION

Findings suggest oral health policies and practices and dental professionals' education and training need reviewing for how well such policies support dental professionals in an Aboriginal context. This includes engaging with Aboriginal stakeholders, working effectively with Aboriginal families, and developing shared understandings about what is needed to increase access to care and improve oral health outcomes for Aboriginal children.

Gastric Emptying Time and Volume of the Small Intestine as Objective Markers in Patients With Symptoms of Diabetic Enteropathy

Background/Aims

Patients with diabetes mellitus (DM) often suffer from gastrointestinal (GI) symptoms, but these correlate poorly to established objective GI motility measures. Our aim is to perform a detailed evaluation of potential measures of gastric and small intestinal motility in patients with DM type 1 and severe GI symptoms.

Methods

Twenty patients with DM and 20 healthy controls (HCs) were included. GI motility was examined with a 3-dimensional-Transit capsule, while organ volumes were determined by CT scans.

Results

Patients with DM and HCs did not differ with regard to median gastric contraction frequency (DM 3.0 contractions/minute [interquartile range {IQR}, 2.9-3.0]; HCs 2.9 [IQR, 2.8-3.1]; P = 0.725), amplitude of gastric contractions (DM 9 mm [IQR, 8-11]; HCs 11 mm (IQR, 9-12); P = 0.151) or fasting volume of the stomach wall (DM 149 cm3 [IQR, 112-187]; HCs 132 cm3 [IQR, 107-154]; P = 0.121). Median gastric emptying time was prolonged in patients (DM 3.3 hours [IQR, 2.6-4.6]; HCs 2.4 hours [IQR, 1.8-2.7]; P = 0.002). No difference was found in small intestinal transit time (DM 5 hours [IQR, 3.7-5.6]; HCs 4.8 hours [IQR, 3.9-6.0]; P = 0.883). However, patients with DM had significantly larger volume of the small intestinal wall (DM 623 cm3 [IQR, 487-766]; HCs 478 cm3 [IQR, 393-589]; P = 0.003). Among patients, 13 (68%) had small intestinal wall volume and 9 (50%) had gastric emptying time above the upper 95% percentile of HCs.

Conclusion

In our study, gastric emptying time and volume of the small intestinal wall appeared to be the best objective measures in patients with DM type 1 and symptoms and gastroenteropathy.

A diet-induced gut microbiota component and related plasma metabolites are associated with depressive-like behaviour in rats

It is well-established in preclinical studies that various probiotics may improve behaviours related to psychiatric disease. We have previously shown that probiotics protected against high-fat diet (HFD)-induced depressive-like behaviour in Flinders Sensitive Line (FSL) rats, whereas FSL rats on control (CON) diet were unaffected. Therefore, we hypothesised that a dysmetabolic component of depression may exist that involves the gut microbiota and that such component may be reflected in the plasma metabolome. The aims of the present study post hoc analyses were 1) to study the effect of probiotics on gut microbiota composition and its association with depressive-like behaviour in FSL rats, and 2) to identify plasma metabolites associated with gut microbiota and depressive-like behaviour. Forty-six FSL rats were fed CON or HFD and treated with multi-species probiotics (nine Bifidobacterium, Lactococcus and Lactobacillus species) for 12 weeks. Faecal samples were collected for 16S rRNA (VR4) gene amplicon sequencing (Illumina MiSeq), and an untargeted plasma metabolomics was performed. We found that probiotics increased the relative faecal abundance of the Bifidobacterium, Lactococcus and Lactobacillus genera in HFD-fed rats only. Also, a HFD-induced microbiota component associated with depressive-like behaviour was identified, and probiotics improved the component score. Finally, the plasma levels of 44 metabolites correlated with the depression-related microbiota component, and three such metabolites had good predictive ability for depressive-like behaviour. Potentially, our findings imply that a subtype of depression characterised by a diet-induced, pro-depressant gut microbiota may exist and that analysis of related plasma metabolites may reveal aberrant microbiota functioning related to depression.

Colonic motility in patients with type 1 diabetes and gastrointestinal symptoms

BACKGROUND

Gastrointestinal (GI) symptoms are common in patients with diabetes mellitus (DM). The electromagnetic 3D-Transit system allows assessment of regional transit times and motility patterns throughout the GI tract. We aimed to compare GI transit times and detailed motility patterns of the colon in patients with DM and GI symptoms to those of healthy controls (HC). We further aimed to determine whether any abnormalities in motility were reversible by cholinergic stimulation.

METHODS

We compared 18 patients with DM with 20 HC by means of the 3D-Transit system. Patients were studied before and during oral administration of 60 mg pyridostigmine.

KEY RESULTS

Compared to HC, patients had prolonged gastric emptying (DM: 3.3 hours (interquartile range (IQR) 2.6-4.6); HC: 2.3 hours (IQR 1.7-2.7) (P < .01)), colonic transit time (DM: 52.6 hours (IQR 23.3-83.0); HC: 22.4 hours (IQR 18.9-43.6) (P = .02)), and whole gut transit time (DM: 69.4 hours (IQR 32.9-103.6); HC: 30.3 hours (IQR 25.2-49.9) (P < .01)). In addition, compared to HC, patients had prolonged transit time in the ascending colon (DM: 20.5 hours (IQR 11.0-44.0); HC: 8.0 hours (IQR 3.8-21.0) (P < .05)) and more slow retrograde movements in the colon (DM: 2 movements (IQR 1-4); HC: 1 movement (IQR 0-1) (P = .01)). In patients, pyridostigmine increased the number of bowel movements (P < .01) and reduced small intestine transit times (P < .05).

CONCLUSIONS

Patients with DM and GI symptoms have longer than normal GI transit times. This is only partly reversible by pyridostigmine. The increased number of retrograde colonic movements in patients could potentially explain the abnormally long transit time in proximal colon.

[Symptoms of diabetic gastroenteropathy in patients with diabetes]

Abdominal pain, nausea, vomiting, diarrhoea, constipation, and faecal incontinence are common symptoms of diabetic gastroenteropathy and often have a major impact on quality of life. The symptoms are usually caused by widespread dysfunction of the gastrointestinal tract. Hence, diagnosis requires panenteric assessment. The general principles of management are glycaemic control, diet, prokinetics, laxatives, and in selected cases, gastric electrical stimulation, which is summarised in this review.

Enteric cholinergic neuropathy in patients with diabetes: Non-invasive assessment with positron emission tomography

BACKGROUND

¹¹ C-Donepezil positron emission tomography (PET) allows non-invasive assessment of cholinergic innervation of visceral organs. We aimed to compare cholinergic innervation in the gut in patients with diabetes mellitus (DM) and in healthy controls (HC).

METHODS

¹¹ C-Donepezil PET and computed tomography (CT) were performed in 19 patients with type 1 DM and gastrointestinal symptoms and in 19 age- and sex-matched HC in a cross-sectional design.

KEY RESULTS

All patients had severe gastrointestinal symptoms when assessed by standard questionnaires. DM patients had significantly increased volume of the small intestinal wall (DM: median 557 cm³ [interquartile range [IQR] 446-697] vs HC median: 448 cm³ [IQR; 341-518; P < .01]), and the ¹¹ C Donepezil PET uptake was reduced in patients (DM: median 7.08 standardized uptake value [SUV] [IQR; 5.94-8.43] vs HC: median 9.18 SUV [IQR; 8.57-10.11; P < .01]). A similar pattern was found in colon (DM: median volume 1064 cm³ [IQR; 882-1312] vs HC: median 939 cm³ [IQR; 785-1081; P = .13] and DM: median 1.22 SUV (IQR; 1.08-1.36) vs HC: median 1.42 SUV (IQR; 1.32-1.53; P = .03). Furthermore, patients had significantly reduced pancreatic volume (DM: median 53 cm³ [IQR; 41-69] vs HC: median 98 cm³ [IQR;82-110; P < .01]) and reduced PET uptake of the pancreas (DM: median 13.14 SUV [IQR;9.58-15.82] vs HC: median 21.46 SUV [IQR;18.97-24.06; P < .01]) as well as the adrenal gland (DM: median 7.62 SUV [IQR;7.61;15.82] vs HC: median 15.51 SUV [IQR;12.22;19.49; P = .03]).

CONCLUSION AND INFERENCES

Assessed with ¹¹ C-Donepezil PET/CT, patients with DM and severe bowel symptoms have reduced cholinergic innervation of the gut indicative of parasympathetic denervation.

The antidepressant-like effect of probiotics and their faecal abundance may be modulated by the cohabiting gut microbiota in rats

Numerous studies have been published describing the effect of various probiotics (PRO) on behaviours related to psychiatric disease. We have previously shown a robust antidepressant-like effect of PRO in rats, but over time, the treatment effect seems to vary significantly between different sets of rats from the same commercial vendor. Therefore, we hypothesised that the antidepressant-like response may be modulated by the cohabiting gut microbiota. The aims of the present study were (1) to investigate any differences in the gut microbiota composition between responders (Resp) and non-responders (Non-resp) to PRO with regards to depressive-like behaviour, and (2) to evaluate the effects of PRO on the microbiota composition. Two sets of 20 male Sprague-Dawley rats each were treated with multi-species PRO (nine Bifidobacterium, Lactococcus and Lactobacillus species) for eight weeks and subjected to a behavioural assessment. Faecal samples were collected for 16 s rRNA (VR4) gene amplicon sequencing (Illumina MiSeq). As previously reported, PRO-treated Resp animals showed a marked decrease in depressive-like behaviour, whereas no such response was seen in Non-resp. We observed profound differences in the gut microbiota composition between the two sets of rats, and the relative faecal abundance of the genera that comprised PRO was higher in Resp than in Non-resp although treated with the same dose of PRO. Particularly, the relative abundance of the Lactobacillus genus was not increased in PRO-treated Non-resp animals. In conclusion, the cohabiting microbiota and the faecal abundance of PRO may modulate the antidepressant-like effect of PRO in rats.

Grandmaternal high-fat diet primed anxiety-like behaviour in the second-generation female offspring

The health consequences of maternal obesity during pregnancy are disturbing as they may contribute to mental disorders in subsequent generations. We examine the influence of suboptimal grandmaternal diet on potential metabolic and mental health outcome of grand-progenies with a high-fat diet (HFD) manipulation in adulthood in a rat HFD model. Grandmaternal exposure to HFD exacerbated granddaughter's anxiety-like phenotype. Grandmaternal exposure to HFD led to upregulated corticotropin-releasing hormone receptor 2 mRNA expression involved in the stress axis in the male F₂ offspring. Thus, we demonstrate that suboptimal grandmaternal diet prior to and during pregnancy and lactation may persist across subsequent generations. These findings have important implications for understanding both individual rates of metabolic and mental health problems and the clinical impact of current global trends towards comorbidity of obesity and depression and anxiety. In conclusion, the effect of grandmaternal HFD consumption during pregnancy on stress axis function and mental disorders may be transmitted to future generations.

The microbial metabolite indole-3-propionic acid improves glucose metabolism in rats, but does not affect behaviour

CONTEXT

We have previously shown that an antidepressant-like effect of probiotics in rats was associated with a higher plasma level of the microbial tryptophan metabolite indole-3-propionic acid (IPA).

OBJECTIVE

We therefore wanted to study the isolated effect of IPA on behaviour and glucose metabolism in rats.

METHODS

Male Sprague-Dawley rats were fed control or IPA-enriched diet for six weeks (n = 12 per group) and assessed in the elevated plus maze, open field and forced swim test. Blood glucose, metabolic hormones and the white blood cell (WBC) composition were analysed.

RESULTS

IPA (mean intake 27.3 mg/kg/day) significantly lowered fasting blood glucose level by 0.42 mM (95% CI 0.11-0.73). Similarly, fasting plasma insulin levels and the homeostatic model assessment (HOMA) index of insulin resistance were reduced, whereas plasma metabolic hormones, behaviour and WBC composition remained unaffected by IPA.

CONCLUSIONS

Our findings highlight IPA as a promising candidate for treatment of metabolic disorders associated with insulin resistance.

DNA methylation in epigenetic inheritance of metabolic diseases through the male germ line

The global rise in metabolic diseases can be attributed to a complex interplay between biology, behavior and environmental factors. This article reviews the current literature concerning DNA methylation-based epigenetic inheritance (intergenerational and transgenerational) of metabolic diseases through the male germ line. Included are a presentation of the basic principles for DNA methylation in developmental programming, and a description of windows of susceptibility for the inheritance of environmentally induced aberrations in DNA methylation and their associated metabolic disease phenotypes. To this end, escapees, genomic regions with the intrinsic potential to transmit acquired paternal epigenetic information across generations by escaping the extensive programmed DNA demethylation that occurs during gametogenesis and in the zygote, are described. The ongoing descriptive and functional examinations of DNA methylation in the relevant biological samples, in conjugation with analyses of non-coding RNA and histone modifications, hold promise for improved delineation of the effect size and mechanistic background for epigenetic inheritance of metabolic diseases.

Escitalopram Ameliorates Hypercortisolemia and Insulin Resistance in Low Birth Weight Men With Limbic Brain Alterations

CONTEXT

Low birth weight (LBW; <2500 g) is linked to the development of insulin resistance and limbic-hypothalamic-pituitary-adrenal (LHPA) axis hyperactivity.

OBJECTIVE

Our first aim was to study insulin action, LHPA axis function, and limbic brain structures in young, healthy LBW men vs normal birthweight (NBW) controls (part 1). Our second aim was to investigate the effects of escitalopram vs placebo in LBW men in the LHPA axis and insulin sensitivity (part 2).

DESIGN SETTING, PARTICIPANTS, AND INTERVENTION

The maximal (Rdmax) and submaximal (Rdsubmax) rates of insulin-stimulated glucose turnover, LHPA axis, and brain morphology were examined in 40 LBW men and 20 matched NBW men using two-stage hyperinsulinemic euglycemic clamp, 24-hour hormone plasma profiles, and magnetic resonance imaging. Subsequently, all LBW subjects underwent randomized and double-blind treatment with escitalopram 20 mg/d or placebo for 3 months followed by a complete reexamination.

MAIN OUTCOME MEASURES (PART 2)

Changes in Rdmax/Rdsubmax and plasma-free cortisol 24-hour area under the curve.

RESULTS

In LBW vs NBW, Rdsubmax and Rdmax were ∼16% (P = 0.01) and ∼12% (P = 0.01) lower, respectively, and 24-hour free cortisol levels were ∼20% higher (P = 0.02), primarily driven by a ∼99% increase at 05:00 am (P < 0.001). Furthermore, these changes were related to structural alterations within left thalamus and ventromedial prefrontal cortex. However, in LBW men, exposure to escitalopram normalized the free cortisol levels and improved the Rdsubmax by ∼24% (P = 0.04) compared with placebo.

CONCLUSIONS

LBW vs NBW displayed alterations in key brain structures modulating the LHPA axis, elevated free cortisol levels, and insulin resistance. Escitalopram administration ameliorated these defects, suggesting a potential for LHPA axis modulation compounds to improve insulin action in LBW subjects.

Probiotic treatment protects against the pro-depressant-like effect of high-fat diet in Flinders Sensitive Line rats

Major depressive disorder (MDD) is highly associated with dysmetabolic conditions, such as obesity and diabetes mellitus type 2, and the gut microbiota may interact with both disease entities. We have previously shown that a high-fat diet (HFD) exacerbated depressive-like behaviour uniquely in Flinders Sensitive Line (FSL) rats that inherently present with an increased level of depressive-like behaviour compared with Flinders Resistant Line (FRL) rats. We therefore investigated whether multispecies probiotics possessed anti-depressant-like effect in FSL rats or protected against the pro-depressant-like effect of HFD. We also examined blood and cerebral T cell subsets as well as plasma cytokines. Lastly, we investigated the effect of HFD in outbred Sprague-Dawley (SD) rats to substantiate the association between depressive-like behaviour and any immunological measures affected by HFD. HFD exacerbated the depressive-like behaviour in FSL rats in the forced swim test, whereas SD rats remained unaffected. Probiotic treatment completely precluded the pro-depressant-like effect of HFD, but it did not affect FSL rats on control diet. Cerebral T lymphocyte CD4/8 ratios closely mirrored the behavioural changes, whereas the proportions of Treg and Th17 subsets were unaltered. No association between blood and brain CD4/8 ratios were evident; nor did plasma cytokine levels change as a consequence of HFD of probiotic treatment. Our findings suggest that MDD may hold a dysmetabolic component that responds to probiotic treatment. This finding has wide implications owing to the high metabolic comorbidity in MDD. Furthermore, the close association between depressive-like behaviour and cerebral T cell populations demonstrate lymphocyte-brain interactions as a promising future research area in the field of psychoneuroimmunology.

[Workup and treatment of gastroparesis]

Gastroparesis is defined as impaired gastric emptying without mechanical obstruction and cardinal symptoms including vomiting, nausea, early satiety, and upper abdominal pain. Most cases of gastroparesis are diabetic, idiopathic or post-operative. The correlation between symptoms and objective measures of gastroparesis is poor. Basic treatment includes dietary advices and prokinetics. Selected patients not responding to basic treatment can be offered gastric electrical stimulation. In many cases, gastroparesis is present in combination with other motility disorders, especially constipation.

Chronic maternal inflammation or high-fat-feeding programs offspring obesity in a sex-dependent manner

BACKGROUND/OBJECTIVES

The current world-wide obesity epidemic partially results from a vicious circle whereby maternal obesity during pregnancy predisposes the offspring for accelerated weight gain and development of metabolic syndrome. Here we investigate whether low-grade inflammation, characteristic of the obese state, provides a causal role for this disastrous fetal programming in mice.

METHODS

We exposed pregnant and lactating C57BL/6JBom female mice to either high-fat diet (HFD), or continuous infusion of lipopolysaccharide (LPS), a potent trigger of innate immunity, and studied offspring phenotypes.

RESULTS

Both maternal LPS or HFD treatments rendered the offspring hyperphagic and inept of coping with a HFD challenge during adulthood, increasing their adiposity and weight gain. The metabolic effects were more pronounced in female offspring, while exposed male offspring mounted a larger inflammatory response to HFD at adulthood.

CONCLUSIONS

This supports our hypothesis and highlights the programming potential of inflammation in obese pregnancies.

Probiotic treatment reduces depressive-like behaviour in rats independently of diet

The gut microbiota has recently emerged as an important regulator of brain physiology and behaviour in animals, and ingestion of certain bacteria (probiotics) therefore appear to be a potential treatment for major depressive disorder (MDD). However, some conceptual and mechanistical aspects need further elucidation. We therefore aimed at investigating whether the habitual diet may interact with the effect of probiotics on depression-related behaviour and further examined some potentially involved mechanisms underlying the microbe-mediated behavioural effects. Forty male Sprague-Dawley rats were fed a control (CON) or high-fat diet (HFD) for ten weeks and treated with either a multi-species probiotic formulation or vehicle for the last five weeks. Independently of diet, probiotic treatment markedly reduced depressive-like behaviour in the forced swim test by 34% (95% CI: 22-44%). Furthermore, probiotic treatment skewed the cytokine production by stimulated blood mononuclear cells towards IFNγ, IL2 and IL4 at the expense of TNFα and IL6. In addition, probiotics lowered hippocampal transcript levels of factors involved in HPA axis regulation (Crh-r1, Crh-r2 and Mr), whereas HFD increased these levels. A non-targeted plasma metabolomics analysis revealed that probiotics raised the level of indole-3-propionic acid, a potential neuroprotective agent. Our findings clearly support probiotics as a potential treatment strategy in MDD. Importantly, the efficacy was not attenuated by intake of a "Western pattern" diet associated with MDD. Mechanistically, the HPA axis, immune system and microbial tryptophan metabolism could be important in this context. Importantly, our study lend inspiration to clinical trials on probiotics in depressed patients.

Slow Phospholipid Exchange between a Detergent-Solubilized Membrane Protein and Lipid-Detergent Mixed Micelles: Brominated Phospholipids as Tools to Follow Its Kinetics

Membrane proteins are largely dependent for their function on the phospholipids present in their immediate environment, and when they are solubilized by detergent for further study, residual phospholipids are critical, too. Here, brominated phosphatidylcholine, a phospholipid which behaves as an unsaturated phosphatidylcholine, was used to reveal the kinetics of phospholipid exchange or transfer from detergent mixed micelles to the environment of a detergent-solubilized membrane protein, the paradigmatic P-type ATPase SERCA1a, in which Trp residues can experience fluorescence quenching by bromine atoms present on phospholipid alkyl chains in their immediate environment. Using dodecylmaltoside as the detergent, exchange of (brominated) phospholipid was found to be much slower than exchange of detergent under the same conditions, and also much slower than membrane solubilization, the latter being evidenced by light scattering changes. The kinetics of this exchange was strongly dependent on temperature. It was also dependent on the total concentration of the mixed micelles, revealing the major role for such exchange of the collision of detergent micelles with the detergent-solubilized protein. Back-transfer of the brominated phospholipid from the solubilized protein to the detergent micelle was much faster if lipid-free DDM micelles instead of mixed micelles were added for triggering dissociation of brominated phosphatidylcholine from the solubilized protein, or in the additional presence of C₁₂E₈ detergent during exchange, also emphasizing the role of the chemical nature of the micelle/protein interface. This protocol using brominated lipids appears to be valuable for revealing the possibly slow kinetics of phospholipid transfer to or from detergent-solubilized membrane proteins. Independently, continuous recording of the activity of the protein can also be used in some cases to correlate changes in activity with the exchange of a specific phospholipid, as shown here by using the Drs2p/Cdc50p complex, a lipid flippase with specific binding sites for lipids.

Registered Replication Report

According to the facial feedback hypothesis, people’s affective responses can be influenced by their own facial expression (e.g., smiling, pouting), even when their expression did not result from their emotional experiences. For example, Strack, Martin, and Stepper (1988) instructed participants to rate the funniness of cartoons using a pen that they held in their mouth. In line with the facial feedback hypothesis, when participants held the pen with their teeth (inducing a “smile”), they rated the cartoons as funnier than when they held the pen with their lips (inducing a “pout”). This seminal study of the facial feedback hypothesis has not been replicated directly. This Registered Replication Report describes the results of 17 independent direct replications of Study 1 from Strack et al. (1988), all of which followed the same vetted protocol. A meta-analysis of these studies examined the difference in funniness ratings between the “smile” and “pout” conditions. The original Strack et al. (1988) study reported a rating difference of 0.82 units on a 10-point Likert scale. Our meta-analysis revealed a rating difference of 0.03 units with a 95% confidence interval ranging from −0.11 to 0.16.

A robust method to screen detergents for membrane protein stabilization, revisited

This report is a follow up of our previous paper (Lund, Orlowski, de Foresta, Champeil, le Maire and Møller (1989), J Biol Chem 264:4907-4915) showing that solubilization in detergent of a membrane protein may interfere with its long-term stability, and proposing a protocol to reveal the kinetics of such irreversible inactivation. We here clarify the fact that when various detergents are tested for their effects, special attention has of course to be paid to their critical micelle concentration. We also investigate the effects of a few more detergents, some of which have been recently advertised in the literature, and emphasize the role of lipids together with detergents. Among these detergents, lauryl maltose neopentyl glycol (LMNG) exerts a remarkable ability, even higher than that of β-dodecylmaltoside (DDM), to protect our test enzyme, the paradigmatic P-type ATPase SERCA1a from sarcoplasmic reticulum. Performing such experiments for one's favourite protein probably remains useful in pre-screening assays testing various detergents.

LPS-Enhanced Glucose-Stimulated Insulin Secretion Is Normalized by Resveratrol

Low-grade inflammation is seen with obesity and is suggested to be a mediator of insulin resistance. The eliciting factor of low-grade inflammation is unknown but increased permeability of gut bacteria-derived lipopolysaccharides (LPS) resulting in endotoxemia could be a candidate. Here we test the effect of LPS and the anti-inflammatory compound resveratrol on glucose homeostasis, insulin levels and inflammation. Mice were subcutaneously implanted with osmotic mini pumps infusing either low-dose LPS or saline for 28 days. Half of the mice were treated with resveratrol delivered through the diet. LPS caused increased inflammation of the liver and adipose tissue (epididymal and subcutaneous) together with enlarged spleens and increased number of leukocytes in the blood. Resveratrol specifically reduced the inflammatory status in epididymal fat (reduced expression of TNFa and Il1b, whereas the increased macrophage infiltration was unaltered) without affecting the other tissues investigated. By LC-MS, we were able to quantitate resveratrol metabolites in epididymal but not subcutaneous adipose tissue. LPS induced insulin resistance as the glucose-stimulated insulin secretion during an oral glucose tolerance test was increased despite similar plasma glucose level resulting in an increase in the insulinogenic index (IGI; delta0-15insulin/delta0-15glucose) from 13.73 to 22.40 pmol/mmol (P < 0.001). This aberration in insulin and glucose homeostasis was normalized by resveratrol.

IN CONCLUSION

Low-dose LPS enhanced the glucose-stimulated insulin secretion without affecting the blood glucose suggesting increased insulin resistance. Resveratrol restored LPS-induced alteration of the insulin secretion and demonstrated anti-inflammatory effects specifically in epididymal adipose tissue possibly due to preferential accumulation of resveratrol metabolites pointing towards a possible important involvement of this tissue for the effects on insulin resistance and insulin secretion.

Gene expression of the zinc transporter ZIP14 (SLC39a14) is affected by weight loss and metabolic status and associates with PPARγ in human adipose tissue and 3T3-L1 pre-adipocytes

Background

The expansion and function of adipose tissue are important during the development of insulin resistance and inflammation in obesity. Zinc dyshomeostasis is common in obese individuals. In the liver, zinc influx transporter ZIP14, affects proliferation and glucose metabolism but the role of ZIP14 in adipose tissue is still unknown. This study investigates ZIP14 gene expression in human adipose tissue before and after weight loss as well as the regulation of ZIP14 during early adipogenesis.

Methods

Fourteen obese individuals were investigated before and after a 10 week weight loss intervention and compared to 14 non-obese controls. Gene expressions of ZIP14 and peroxisome proliferator-activated receptor γ (PPARγ) were measured in subcutaneous adipose tissue and correlated with metabolic and inflammatory markers. Further, we investigated gene expression of ZIP14 and PPARγ during early adipogenesis of 3T3-L1 pre-adipocytes, together with an in silico analysis of PPARγ binding motifs in the promoter sequence of ZIP14.

Results

ZIP14 was down-regulated in obese individuals compared to non-obese controls (p = 0.0007) and was up-regulated after weight loss (p = 0.0005). Several metabolic markers of clinical importance, including body mass index, triglyceride, and insulin resistance, were inversely correlated with ZIP14. During early adipogensis an up-regulation of ZIP14 gene expression was found. PPARγ gene expression was positively correlated with the ZIP14 gene expression in both adipose tissue and during adipogenesis. However, in silico analysis revealed that the ZIP14 promoter does not contain PPARγ-binding motifs.

Conclusions

We hypothesize that ZIP14-mediated zinc influx might directly influence PPARγ activity and that ZIP14 may regulate expansion and function of adipose tissue and serve as a potential biomarker for metabolic stress.

Electronic supplementary material

The online version of this article (doi:10.1186/s40608-015-0076-y) contains supplementary material, which is available to authorized users.

Chronic exposure to low doses of lipopolysaccharide and high-fat feeding increases body mass without affecting glucose tolerance in female rats

Obesity-related inflammation may have a causal role in the development of diabetes and insulin resistance, and studies using animal models of chronic experimental endotoxemia have shown the link. However, many studies use only males, and much less is known about the role of obesity-related inflammation in females. Therefore, we addressed how experimentally induced chronic inflammation affects body mass, energy intake, and glucose metabolism in female rats. Adult female Sprague Dawley rats were instrumented with slow release pellets that delivered a constant daily dose of 53 or 207 μg of lipopolysaccharide (LPS) per rat for 60 days. Control rats were instrumented with vehicle pellets. Due to inflammatory nature of high-fat diet (HFD) half of the rats received HFD (60% of calories from lard), while the other half remained on control diet to detect possible interactions between two modes of induced inflammation. Our results showed that chronic LPS administration increased female rat body mass and calorie intake in a dose-dependent manner, and that HFD further exacerbated these effects. Despite these effects, no effects of LPS and HFD were evident on female rat glucose metabolism. Only LPS elevated expression of inflammatory markers in the hypothalamus. To conclude, female rats respond to experimentally induced chronic inflammation by increasing body mass, but do not develop glucose intolerance in the given period of time.

Behavioral and systemic consequences of long-term inflammatory challenge

Inflammatory reactions are involved in a diversity of diseases, including major depressive disorder. Cytokines act as intercellular signaling molecules and mediators of inflammation between the periphery and the brain. Within the brain, evidence from animal studies of acute inflammation has shown that elevated cytokine levels are linked to behavioral responses of sickness and depression-like behavior. Although chronic inflammation is more translational to human depression than acute studies, little is known on central cytokine expression and associated behavioral responses following chronic immune challenges. The present study assessed behavioral changes and a selection of cytokines in the brain and in the blood in rats randomized to receive a single or 8week administration with either lipopolysaccharide (LPS, 600μg/kg, i.p.) or saline. Acute and long-term LPS treatments caused similar sickness and depression-like behavior. Chronic LPS administration did not have an effect on blood cytokine levels, indicating endotoxin tolerance, whereas increased fasting blood glucose was observed, indicating insulin resistance, a metabolic consequence of chronic inflammation. While a single LPS injection produced a generalized cytokine response in the brain, long-term LPS administration produced a specific central cytokine response with increased interleukin (IL)-1β and interferon (IFN)-γ. These cytokines can explain the behavioral changes observed, and could indicate microglia activation, although future studies are needed to uncover this assumption. Taken together, although the behavioral outcome was similar between acute and chronic LPS administration, the central cytokine response was distinct. As the long-term LPS paradigm also posed a metabolic demand, this setting may reflect a more translational insight into inflammatory reactions in human depression, and could prove useful for assessing cytokine down-stream effects and experimental antidepressant drug products.

Effects of ambient temperature on glucose tolerance and insulin sensitivity test outcomes in normal and obese C57 male mice

Mice are commonly used as animal models to study human metabolic diseases, but experiments are typically performed at room temperature, which is far below their thermoneutral zone and is associated with elevated heart rate, food intake, and energy expenditure. We set out to study how ambient temperature affects glucose tolerance and insulin sensitivity in control and obese male mice. Adult male C57BL/6J mice were housed at room temperature (23°C) for 6 weeks and fed either control or high fat diet. They were then fasted for 6 h before glucose or insulin tolerance tests were performed at 15, 20, 25, or 30°C. To ensure that behavioral thermoregulation did not counterbalance the afflicted ambient temperatures, oxygen consumption was determined on mice with the same thermoregulatory opportunities as during the tests. Decreasing ambient temperatures increased oxygen consumption and body mass loss during fasting in both groups. Mice fed high fat diet had improved glucose tolerance at 30°C and increased levels of fasting insulin followed by successive decrease of fasting glucose. However, differences between control and high-fat diet mice were present at all temperatures. Ambient temperature did not affect glucose tolerance in control group and insulin tolerance in either of the groups. Ambient temperature affects glucose metabolism in mice and this effect is phenotype specific.

Background intensity correction for terabyte-sized time-lapse images

Several computational challenges associated with large-scale background image correction of terabyte-sized fluorescent images are discussed and analysed in this paper. Dark current, flat-field and background correction models are applied over a mosaic of hundreds of spatially overlapping fields of view (FOVs) taken over the course of several days, during which the background diminishes as cell colonies grow. The motivation of our work comes from the need to quantify the dynamics of OCT-4 gene expression via a fluorescent reporter in human stem cell colonies. Our approach to background correction is formulated as an optimization problem over two image partitioning schemes and four analytical correction models. The optimization objective function is evaluated in terms of (1) the minimum root mean square (RMS) error remaining after image correction, (2) the maximum signal-to-noise ratio (SNR) reached after downsampling and (3) the minimum execution time. Based on the analyses with measured dark current noise and flat-field images, the most optimal GFP background correction is obtained by using a data partition based on forming a set of submosaic images with a polynomial surface background model. The resulting image after correction is characterized by an RMS of about 8, and an SNR value of a 4 × 4 downsampling above 5 by Rose criterion. The new technique generates an image with half RMS value and double SNR value when compared to an approach that assumes constant background throughout the mosaic. We show that the background noise in terabyte-sized fluorescent image mosaics can be corrected computationally with the optimized triplet (data partition, model, SNR driven downsampling) such that the total RMS value from background noise does not exceed the magnitude of the measured dark current noise. In this case, the dark current noise serves as a benchmark for the lowest noise level that an imaging system can achieve. In comparison to previous work, the past fluorescent image background correction methods have been designed for single FOV and have not been applied to terabyte-sized images with large mosaic FOVs, low SNR and diminishing access to background information over time as cell colonies span entirely multiple FOVs. The code is available as open-source from the following link https://isg.nist.gov/.

Dissecting adipose tissue lipolysis: molecular regulation and implications for metabolic disease

Lipolysis is the process by which triglycerides (TGs) are hydrolyzed to free fatty acids (FFAs) and glycerol. In adipocytes, this is achieved by sequential action of adipose TG lipase (ATGL), hormone-sensitive lipase (HSL), and monoglyceride lipase. The activity in the lipolytic pathway is tightly regulated by hormonal and nutritional factors. Under conditions of negative energy balance such as fasting and exercise, stimulation of lipolysis results in a profound increase in FFA release from adipose tissue (AT). This response is crucial in order to provide the organism with a sufficient supply of substrate for oxidative metabolism. However, failure to efficiently suppress lipolysis when FFA demands are low can have serious metabolic consequences and is believed to be a key mechanism in the development of type 2 diabetes in obesity. As the discovery of ATGL in 2004, substantial progress has been made in the delineation of the remarkable complexity of the regulatory network controlling adipocyte lipolysis. Notably, regulatory mechanisms have been identified on multiple levels of the lipolytic pathway, including gene transcription and translation, post-translational modifications, intracellular localization, protein-protein interactions, and protein stability/degradation. Here, we provide an overview of the recent advances in the field of AT lipolysis with particular focus on the molecular regulation of the two main lipases, ATGL and HSL, and the intracellular and extracellular signals affecting their activity.

Gender-specific effect of physical training on AQP7 protein expression in human adipose tissue

AQP7 is a glycerol channel in adipose tissue with a suggested role in controlling the accumulation of triglycerides and secondly development of obesity and type-2 diabetes. In the present study, we aimed to test the hypotheses that (1) AQP7 is localized to the capillaries within human adipose tissue, (2) genetic predisposition to type-2 diabetes is associated with a low expression of AQP7 in abdominal subcutaneous adipose tissue (SAT) and (3) physical training increases AQP7 expression in SAT. The cellular localization of AQP7 in adipose tissue was investigated by immunohistochemistry. The relative expression of AQP7 protein in abdominal SAT was analysed before and after ending a 10-week exercise training programme in first-degree relatives to type-2 diabetic patients and control individuals. Non-obese first-degree relatives to type-2 diabetic patients (n = 20) and control (n = 11) men and women participated in this study. By this, we find that AQP7 is localized to the capillary endothelial cells within adipose tissue. We were unable to evidence a link between a low AQP7 abundance in SAT and genetic predisposition type-2 diabetes. Instead we demonstrate that physical training influences the expression of AQP7 in SAT in a gender-specific manner. Thus, women responds by increasing the abundance of AQP7 by 2.2-fold (p = 0.03) whereas in men a reduced expression is observed (p = 0.00009), resulting in a more than twofold higher abundance of AQP7 in women as compared with men. In conclusion, the adipose tissue glycerol channel, AQP7, is regulated in response to physical training in a gender-dependent manner in SAT.

Metabolic impacts of high dietary exposure to persistent organic pollutants in mice

Persistent organic pollutants (POPs) have been linked to metabolic diseases. Yet, the effects of high exposure to dietary POPs remain unclear. We therefore investigated whether elevated exposure to POPs provided by whale meat supplementation could contribute to insulin resistance. C57BL/6J mice were fed control (C) or very high-fat diet (VHF) containing low or high levels of POPs (VHF(+POPs)) for eight weeks. To elevate the dietary concentrations of POPs, casein was replaced by whale meat containing high levels of pollutants. Feeding VHF(+POPs) induced high POP accumulation in the adipose tissue of mice. However, compared with VHF-fed mice, animals fed VHF(+POPs) had improved insulin sensitivity and glucose tolerance, and reduced body weight. Levels of ectopic fat in skeletal muscles and liver were reduced in mice fed VHF(+POPs). These mice also gained less adipose tissue and had a tendency to reduced energy intake. In pair-feeding experiments, improved insulin action and reduced body weight gain were still observed in VHF(+POPs) compared to VHF pair-fed mice. We concluded that mice fed VHF contaminated with POPs derived from whale meat remain sensitive to insulin and glucose tolerant despite significant body burden of POPs. This indicates complex interactions between organic pollutants and nutrition in the development of metabolic disorders.

Reduced mRNA and protein expression of perilipin A and G0/G1 switch gene 2 (G0S2) in human adipose tissue in poorly controlled type 2 diabetes

CONTEXT

Increased lipolysis and free fatty acid (FFA) levels contribute significantly to the pathogenesis of chronic and acute insulin resistance in type 2 diabetes, but the underlying mechanisms are uncertain.

OBJECTIVE

Our objective was to test whether increased lipolysis and FFA levels induced by insulin withdrawal are accompanied by increased adipose tissue (AT) contents of adipose triglyceride lipase (ATGL) and/or altered intracellular ATGL regulation.

DESIGN AND PARTICIPANTS

Nine patients with type 2 diabetes were examined twice in a randomized crossover design after 16 h of 1) hyperglycemia/insulin withdrawal and 2) euglycemia/insulin infusion. Blood samples were drawn and a sc abdominal AT biopsy was obtained.

SETTING

The study was conducted at a university hospital research unit.

RESULTS

Circulating glucose (7.2 ± 0.3 vs. 11.2 ± 0.8 mmol/liter) and FFA (0.51 ± 0.05 vs. 0.65 ± 0.04 mmol/liter) were increased and insulin levels decreased after insulin withdrawal. AT ATGL protein tended to be increased (P = 0.075) after insulin withdrawal; by contrast, AT protein and mRNA content of perilipin A (Plin) and G(0)/G(1) switch gene 2 (G0S2), known negative regulators of ATGL activity, were decreased by 20-30% (all P values <0.03). All measured parameters related to hormone-sensitive lipase remained unaffected.

CONCLUSIONS

We found reduced mRNA and protein content of Plin and G0S2 and borderline increased ATGL protein in sc AT from poorly controlled type 2 diabetic subjects. This suggests that increased ATGL activity may contribute to the elevated lipolysis and circulating FFA levels in acute insulin withdrawal and metabolic dysregulation in type 2 diabetic patients and that this mechanism may be modifiable.

Estrogen prevents increased hepatic aquaporin-9 expression and glycerol uptake during starvation

In starvation, glycerol is released from adipose tissue and serves as an important precursor for hepatic gluconeogenesis. By unknown sex-specific mechanisms, women suppress the endogenous glucose production better than men and respond to metabolic stress with higher plasma glycerol levels. Hepatic glycerol uptake is facilitated by aquaporin-9 (AQP9), a broad-selectivity neutral solute channel, and represents an insulin-regulated step in supplying gluconeogenesis with glycerol. In the present study, hepatic AQP9 abundance was increased 2.6-fold in starved male rats as assessed by immunoblotting and immunohistochemistry. By contrast, starvation had no significant effect on hepatic AQP9 expression in female rats. Coordinately, plasma glycerol levels remained unchanged with starvation in male rats, whereas it was increased in female rats. The different responses to starvation were paralleled by higher glycerol permeability in basolateral hepatocyte membranes from starved male rats compared with starved females. Ovariectomy led to a starvation-response pattern identical to that observed in male rats with increased hepatic AQP9 expression and unchanged plasma glycerol levels. In cultured hepatocytes, 17β-estradiol and the selective estrogen receptor α-agonist, propyl pyrazole triol, caused a decrease in AQP9 expression. Our results support that a sex-specific regulation of the hepatic glycerol channel AQP9 during starvation contributes to the higher plasma glycerol levels observed in women during fasting and possibly results in a lower cytosolic availability of glycerol. Furthermore, the sexual dimorphism in the hepatic handling of glycerol during starvation might be explained by 17β-estradiol preventing the starvation-induced increase in hepatic AQP9 abundance.

GLUT4 and UBC9 protein expression is reduced in muscle from type 2 diabetic patients with severe insulin resistance

Aims

Subgroups of patients with type 2 diabetes mellitus demand large insulin doses to maintain euglycemia. These patients are characterized by severe skeletal muscle insulin resistance and the underlying pathology remains unclear. The purpose of this study was to examine protein expression of the principal glucose transporter, GLUT4, and associated proteins in skeletal muscle from type 2 diabetic patients characterized by severe insulin resistance.

Methods

Seven type 2 diabetic patients with severe insulin resistance (mean insulin dose 195 IU/day) were compared with seven age matched type 2 diabetic patients who did not require insulin treatment, and with an age matched healthy control group. Protein expression of GLUT4 and associated proteins was assessed in muscle and fat biopsies using standard western blotting techniques.

Results

GLUT4 protein expression was significantly reduced by ∼30 pct in skeletal muscle tissue from severely insulin resistant type 2 diabetic subjects, compared with both healthy controls and type 2 diabetic subjects that did not require insulin treatment. In fat tissue, GLUT4 protein expression was reduced in both diabetic groups. In skeletal muscle, the reduced GLUT4 expression in severe insulin resistance was associated with decreased ubiquitin-conjugating enzyme 9 (UBC9) expression while expression of GLUT1, TBC1D1 and AS160 was not significantly different among type 2 diabetic patients and matched controls.

Conclusions

Type 2 diabetic patients with severe insulin resistance have reduced expression of GLUT4 in skeletal muscle compared to patients treated with oral antidiabetic drugs alone. GLUT4 protein levels may therefore play a role in the pathology behind type 2 diabetes mellitus among subgroups of patients, and this may explain the heterogeneous response to insulin treatment. This new finding contributes to the understanding of the underlying mechanisms for the development of extreme insulin resistance.

Chronic consumption of farmed salmon containing persistent organic pollutants causes insulin resistance and obesity in mice

Background

Dietary interventions are critical in the prevention of metabolic diseases. Yet, the effects of fatty fish consumption on type 2 diabetes remain unclear. The aim of this study was to investigate whether a diet containing farmed salmon prevents or contributes to insulin resistance in mice.

Methodology/Principal Findings

Adult male C57BL/6J mice were fed control diet (C), a very high-fat diet without or with farmed Atlantic salmon fillet (VHF and VHF/S, respectively), and Western diet without or with farmed Atlantic salmon fillet (WD and WD/S, respectively). Other mice were fed VHF containing farmed salmon fillet with reduced concentrations of persistent organic pollutants (VHF/S_-POPs). We assessed body weight gain, fat mass, insulin sensitivity, glucose tolerance, ex vivo muscle glucose uptake, performed histology and immunohistochemistry analysis, and investigated gene and protein expression. In comparison with animals fed VHF and WD, consumption of both VHF/S and WD/S exaggerated insulin resistance, visceral obesity, and glucose intolerance. In addition, the ability of insulin to stimulate Akt phosphorylation and muscle glucose uptake was impaired in mice fed farmed salmon. Relative to VHF/S-fed mice, animals fed VHF/S_-POPs had less body burdens of POPs, accumulated less visceral fat, and had reduced mRNA levels of TNFα as well as macrophage infiltration in adipose tissue. VHF/S_-POPs-fed mice further exhibited better insulin sensitivity and glucose tolerance than mice fed VHF/S.

Conclusions/Significance

Our data indicate that intake of farmed salmon fillet contributes to several metabolic disorders linked to type 2 diabetes and obesity, and suggest a role of POPs in these deleterious effects. Overall, these findings may participate to improve nutritional strategies for the prevention and therapy of insulin resistance.