Diagnostic and referral pathways in patients with rare lipodystrophy and insulin-resistance syndromes: key milestones assessed from a national reference center

BACKGROUND

Rare syndromes of lipodystrophy and insulin-resistance display heterogeneous clinical expressions. Their early recognition, diagnosis and management are required to avoid long-term complications.

OBJECTIVE

We aimed to evaluate the patients' age at referral to our dedicated national reference center in France and their elapsed time from first symptoms to diagnosis and access to specialized care.

PATIENTS AND METHODS

We analyzed data from patients with rare lipodystrophy and insulin-resistance syndromes referred to the coordinating PRISIS reference center (Adult Endocrine Department, Saint-Antoine Hospital, AP-HP, Paris), prospectively recorded between 2018 and 2023 in the French National Rare Disease Database (BNDMR, Banque Nationale de Données Maladies Rares).

RESULTS

A cohort of 292 patients was analyzed, including 208 women, with the following diagnosis: Familial Partial LipoDystrophy (FPLD, n = 124, including n = 67 FPLD2/Dunnigan Syndrome); Acquired lipodystrophy syndromes (n = 98, with n = 13 Acquired Generalized Lipodystrophy, AGL); Symmetric cervical adenolipomatosis (n = 27, Launois-Bensaude syndrome, LB), Congenital generalized lipodystrophy (n = 18, CGL) and other rare severe insulin-resistance syndromes (n = 25). The median age at referral was 47.6 years [IQR: 31-60], ranging from 25.2 (CGL) to 62.2 years old (LB). The median age at first symptoms of 27.6 years old [IQR: 16.8-42.0]) and the median diagnostic delay of 6.4 years [IQR: 1.3-19.5] varied among diagnostic groups. The gender-specific expression of lipodystrophy is well-illustrated in the FPLD2 group (91% of women), presenting with first signs at 19.3 years [IQR: 14.4-27.8] with a diagnostic delay of 10.5 years [IQR: 1.8-27.0].

CONCLUSION

The national rare disease database provides an important tool for assessment of care pathways in patients with lipodystrophy and rare insulin-resistance syndromes in France. Improving knowledge to reduce diagnostic delay is an important objective of the PRISIS reference center.

Biological markers of adipose tissue: Adipokines

We currently have a large sum of clinical and experimental data documenting the involvement of numerous adipokines in the maintenance of energy homeostasis in healthy individuals and their dysregulation in diseases such as obesity, metabolic syndrome or type 2 diabetes. Despite the impressive discoveries made in this field over many years, much remains to be done before understanding all the physiological and pathological implications, and hoping for the development of other effective and safe therapeutic strategies. Two original adipokines will be taken as examples to illustrate these remarks, chemerin and neuregulin 4.

Adipocyte Glucocorticoid Receptor Activation With High Glucocorticoid Doses Impairs Healthy Adipose Tissue Expansion by Repressing Angiogenesis

In humans, glucocorticoids (GCs) are commonly prescribed because of their anti-inflammatory and immunosuppressive properties. However, high doses of GCs often lead to side effects, including diabetes and lipodystrophy. We recently reported that adipocyte glucocorticoid receptor (GR)-deficient (AdipoGR-KO) mice under corticosterone (CORT) treatment exhibited a massive adipose tissue (AT) expansion associated with a paradoxical improvement of metabolic health compared with control mice. However, whether GR may control adipose development remains unclear. Here, we show a specific induction of hypoxia-inducible factor 1α (HIF-1α) and proangiogenic vascular endothelial growth factor A (VEGFA) expression in GR-deficient adipocytes of AdipoGR-KO mice compared with control mice, together with an increased adipose vascular network, as assessed by three-dimensional imaging. GR activation reduced HIF-1α recruitment to the Vegfa promoter resulting from Hif-1α downregulation at the transcriptional and posttranslational levels. Importantly, in CORT-treated AdipoGR-KO mice, the blockade of VEGFA by a soluble decoy receptor prevented AT expansion and the healthy metabolic phenotype. Finally, in subcutaneous AT from patients with Cushing syndrome, higher VEGFA expression was associated with a better metabolic profile. Collectively, these results highlight that adipocyte GR negatively controls AT expansion and metabolic health through the downregulation of the major angiogenic effector VEGFA and inhibition of vascular network development.

ARTICLE HIGHLIGHTS

Perinatal, metabolic, and reproductive features in PPARG-related lipodystrophy

OBJECTIVE

The adipogenic PPARG-encoded PPARγ nuclear receptor also displays essential placental functions. We evaluated the metabolic, reproductive, and perinatal features of patients with PPARG-related lipodystrophy.

METHODS

Current and retrospective data were collected in patients referred to a National Rare Diseases Reference Centre.

RESULTS

26 patients from 15 unrelated families were studied (18 women, median age 43 years). They carried monoallelic PPARG variants except a homozygous patient with congenital generalized lipodystrophy. Among heterozygous patients aged 16 or more (n = 24), 92% had diabetes, 96% partial lipodystrophy (median age at diagnosis 24 and 37 years), 78% hypertriglyceridaemia, 71% liver steatosis, and 58% hypertension. The mean BMI was 26 ± 5.0 kg/m2. Women (n = 16) were frequently affected by acute pancreatitis (n = 6) and/or polycystic ovary syndrome (n = 12). Eleven women obtained one or several pregnancies, all complicated by diabetes (n = 8), hypertension (n = 4), and/or hypertriglyceridaemia (n = 10). We analysed perinatal data of patients according to the presence (n = 8) or absence (n = 9) of a maternal dysmetabolic environment. The median gestational age at birth was low in both groups (37 and 36 weeks of amenorrhea, respectively). As expected, the birth weight was higher in patients exposed to a foetal dysmetabolic environment of maternal origin. In contrast, 85.7% of non-exposed patients, in whom the variant is, or is very likely to be, paternally-inherited, were small for gestational age.

CONCLUSIONS

Lipodystrophy-related PPARG variants induce early metabolic complications. Our results suggest that placental expression of PPARG pathogenic variants carried by affected foetuses could impair prenatal growth and parturition. This justifies careful pregnancy monitoring in affected families.

The ERICH3 rs11580409 polymorphism is associated with 6-month antidepressant response in depressed patients

INTRODUCTION

Major Depressive Disorder (MDD) is the current leading cause of disability worldwide. The effect of its main treatment option, antidepressant drugs (AD), is influenced by genetic and metabolic factors. The ERICH3 rs11580409(A > C) genetic polymorphism was identified as a factor influencing serotonin (5HT) levels in a pharmacometabolomics-informed genome-wide association study. It was also associated with response following AD treatment in several cohorts of depressed patients.

OBJECTIVE

Our aim was to analyze the association of the ERICH3 rs11580409(A > C) genetic polymorphism with response following AD treatment and plasma 5HT levels in METADAP, a cohort of 6-month AD-treated depressed patients.

METHODS

Clinical (n = 377) and metabolic (n = 150) data were obtained at baseline and after 3 (M3) and 6 months (M6) of treatment. Linear mixed-effects models and generalized logistic mixed-effects models were used to assess the association of the rs11580409 polymorphism with the Hamilton Depression Rating Scale (HDRS) score, response and remission rates, and plasma 5HT levels.

RESULTS

The interaction between the ERICH3 rs11580409 polymorphism and time was an overall significant factor in mixed-effects models of the HDRS score (F_3,870 = 3.35, P = 0.019). At M6, CC homozygotes had a significantly lower HDRS score compared to A allele carriers (coefficient = -3.50, 95%CI [-6.00--0.99], P = 0.019). No association between rs11580409 and 5HT levels was observed.

CONCLUSION

Our results suggest an association of rs11580409 with response following long-term AD treatment. The rs11580409 genetic polymorphism may be a useful biomarker for treatment response in major depression.

The necroptosis-inducing pseudokinase mixed lineage kinase domain-like regulates the adipogenic differentiation of pre-adipocytes

Receptor-interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like (MLKL) proteins are key regulators of necroptosis, a highly pro-inflammatory mode of cell death, which has been involved in various human diseases. Necroptotic-independent functions of RIPK3 and MLKL also exist, notably in the adipose tissue but remain poorly defined. Using knock-out (KO) cell models, we investigated the role of RIPK3 and MLKL in adipocyte differentiation. Mlkl-KO abolished white adipocyte differentiation via a strong expression of Wnt10b, a ligand of the Wnt/β-catenin pathway, and a downregulation of genes involved in lipid metabolism. This effect was not recapitulated by the ablation of Ripk3. Conversely, Mlkl and Ripk3 deficiencies did not block beige adipocyte differentiation. These findings indicate that RIPK3 and MLKL have distinct roles in adipogenesis. The absence of MLKL blocks the differentiation of white, but not beige, adipocytes highlighting the therapeutic potential of MLKL inhibition in obesity.

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Mlkl deficiency inhibits white, but not beige, adipocyte differentiation

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MLKL deficiency suppresses the expression of master regulators of adipogenesis

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Mlkl deficiency up-regulates Wnt10b expression

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Ripk3 deficiency does not alter white and beige adipocyte differentiation

Increased atherosclerotic plaque in AOC3 knock-out in ApoE−/− mice and characterization of AOC3 in atherosclerotic human coronary arteries

Introduction

Amine oxidase copper containing 3 (AOC3) displays adhesion between leukocytes and endothelial cells and enzymatic functions. Given its controversial role in atherogenesis, we proposed to investigate the involvement of AOC3 in the formation of atherosclerotic plaques in ApoE^−/−AOC3^−/− mice and human coronary arteries.

Methods

Lesions, contractile markers, and AOC3 were studied in aortic tissues from 15- and 25-week-old mice and different stages of human coronary atherosclerotic arteries by immunohistochemistry (IHC) and/or western blot. Human VSMCs, treated or not with LJP1586, an AOC3 inhibitor, were used to measure differentiation markers by qPCR. AOC3 co-localization with specific cell markers was studied by using confocal microscopy in mice and human samples.

Results

At 15 weeks old, the absence of AOC3 was associated with increased lesion size, α-SMA, and CD3 staining in the plaque independently of a cholesterol modification. At 25 weeks old, advanced plaques were larger with equivalent staining for α-SMA while CD3 increased in the media from ApoE^−/−AOC3^−/− mice. At both ages, the macrophage content of the lesion was not modified. Contractile markers decreased whereas MCP-1 appeared augmented only in the 15-week-old ApoE^−/−AOC3. AOC3 is mainly expressed by mice and human VSMC is slightly expressed by endothelium but not by macrophages.

Conclusion

AOC3 knock-out increased atherosclerotic plaques at an early stage related to a VSMC dedifferentiation associated with a higher T cells recruitment in plaques explained by the MCP-1 augmentation. This suggests that AOC3 may have an important role in atherosclerosis independent of its canonical inflammatory effect. The dual role of AOC3 impacts therapeutic strategies using pharmacological regulators of SSAO activity.

Inhibition of Adipose Tissue Beiging by HIV Integrase Inhibitors, Dolutegravir and Bictegravir, Is Associated with Adipocyte Hypertrophy, Hypoxia, Elevated Fibrosis, and Insulin Resistance in Simian Adipose Tissue and Human Adipocytes

For people living with HIV, treatment with integrase-strand-transfer-inhibitors (INSTIs) can promote adipose tissue (AT) gain. We previously demonstrated that INSTIs can induce hypertrophy and fibrosis in AT of macaques and humans. By promoting energy expenditure, the emergence of beige adipocytes in white AT (beiging) could play an important role by limiting excess lipid storage and associated adipocyte dysfunction. We hypothesized that INSTIs could alter AT via beiging inhibition. Fibrosis and gene expression were measured in subcutaneous (SCAT) and visceral AT (VAT) from SIV-infected, dolutegravir-treated (SIVART) macaques. Beiging capacity was assessed in human adipose stromal cells (ASCs) undergoing differentiation and being exposed to dolutegravir, bictegravir, or raltegravir. Expression of beige markers, such as positive-regulatory-domain-containing-16 (PRDM16), were lower in AT of SIVART as compared to control macaques, whereas fibrosis-related genes were higher. Dolutegravir and bictegravir inhibited beige differentiation in ASCs, as shown by lower expression of beige markers and lower cell respiration. INSTIs also induced a hypertrophic insulin-resistant state associated with a pro-fibrotic phenotype. Our results indicate that adipocyte hypertrophy induced by INSTIs is involved via hypoxia (revealed by a greater hypoxia-inducible-factor-1-alpha gene expression) in fat fibrosis, beiging inhibition, and thus (via positive feedback), probably, further hypertrophy and associated insulin resistance.

The resolvin D2 - GPR18 axis is expressed in human coronary atherosclerosis and transduces atheroprotection in apolipoprotein E deficient mice

Chronic inflammation in atherosclerosis reflects a failure in the resolution of inflammation. Pro-resolving lipid mediators derived from omega-3 fatty acids reduce the development of atherosclerosis in murine models. The aim of the present study was to decipher the role of the specialized proresolving mediator (SPM) resolvin D2 (RvD2) in atherosclerosis and its signaling through the G-protein coupled receptor (GPR) 18. The ligand and receptor were detected in human coronary arteries in relation to the presence of atherosclerotic lesions and its cellular components. Importantly, RvD2 levels were significantly higher in atherosclerotic compared with healthy human coronary arteries. Furthermore, apolipoprotein E (ApoE) deficient hyperlipidemic mice were treated with either RvD2 or vehicle in the absence and presence of the GPR18 antagonist O-1918. RvD2 significantly reduced atherosclerosis, necrotic core, and pro-inflammatory macrophage marker expression. RvD2 in addition enhanced macrophage phagocytosis. The beneficial effects of RvD2 were not observed in the presence of O-1918. Taken together, these results provide evidence of atheroprotective pro-resolving signalling through the RvD2-GPR18 axis.

When therapeutic drugs lead to diabetes

Drug-induced diabetes mellitus is a growing problem in clinical practice. New, potent medications contribute to this problem in a population already at high risk of developing glucose disturbances because of poor lifestyle habits and high prevalence of being overweight/obese. The present review focuses on four important pharmacological classes: glucocorticoids; antipsychotics, especially second generation; antiretroviral therapies, which revolutionised the management of individuals with HIV; and immune checkpoint inhibitors, recently used for the immunotherapy of cancer. For each class, the prevalence of drug-induced diabetes will be evaluated, the most common clinical presentations will be described, the underlying mechanisms leading to hyperglycaemia will be briefly analysed, and some recommendations for appropriate monitoring and management will be proposed.

Dunnigan lipodystrophy syndrome: French National Diagnosis and Care Protocol (PNDS; Protocole National de Diagnostic et de Soins)

Dunnigan syndrome, or Familial Partial Lipodystrophy type 2 (FPLD2; ORPHA 2348), is a rare autosomal dominant disorder due to pathogenic variants of the LMNA gene. The objective of the French National Diagnosis and Care Protocol (PNDS; Protocole National de Diagnostic et de Soins), is to provide health professionals with a guide to optimal management and care of patients with FPLD2, based on a critical literature review and multidisciplinary expert consensus. The PNDS, written by members of the French National Reference Center for Rare Diseases of Insulin Secretion and Insulin Sensitivity (PRISIS), is available on the French Health Authority website (in French). Dunnigan syndrome is characterized by a partial atrophy of the subcutaneous adipose tissue and by an insulin resistance syndrome, associated with a risk of metabolic, cardiovascular and muscular complications. Its prevalence, assessed at 1/100.000 in Europe, is probably considerably underestimated. Thorough clinical examination is key to diagnosis. Biochemical testing frequently shows hyperinsulinemia, abnormal glucose tolerance and hypertriglyceridemia. Elevated hepatic transaminases (hepatic steatosis) and creatine phosphokinase, and hyperandrogenism in women, are common. Molecular analysis of the LMNA gene confirms diagnosis and allows for family investigations. Regular screening and multidisciplinary monitoring of the associated complications are necessary. Diabetes frequently develops from puberty onwards. Hypertriglyceridemia may lead to acute pancreatitis. Early atherosclerosis and cardiomyopathy should be monitored. In women, polycystic ovary syndrome is common. Overall, the management of patients with Dunnigan syndrome requires the collaboration of several health care providers. The attending physician, in conjunction with the national care network, will ensure that the patient receives optimal care through regular follow-up and screening. The various elements of this PNDS are described to provide such a support.

Loss of thymidine phosphorylase activity disrupts adipocyte differentiation and induces insulin-resistant lipoatrophic diabetes

BACKGROUND

Thymidine phosphorylase (TP), encoded by the TYMP gene, is a cytosolic enzyme essential for the nucleotide salvage pathway. TP catalyzes the phosphorylation of the deoxyribonucleosides, thymidine and 2'-deoxyuridine, to thymine and uracil. Biallelic TYMP variants are responsible for Mitochondrial NeuroGastroIntestinal Encephalomyopathy (MNGIE), an autosomal recessive disorder characterized in most patients by gastrointestinal and neurological symptoms, ultimately leading to death. Studies on the impact of TYMP variants in cellular systems with relevance to the organs affected in MNGIE are still scarce and the role of TP in adipose tissue remains unexplored.

METHODS

Deep phenotyping was performed in three patients from two families carrying homozygous TYMP variants and presenting with lipoatrophic diabetes. The impact of the loss of TP expression was evaluated using a CRISPR-Cas9-mediated TP knockout (KO) strategy in human adipose stem cells (ASC), which can be differentiated into adipocytes in vitro. Protein expression profiles and cellular characteristics were investigated in this KO model.

RESULTS

All patients had TYMP loss-of-function variants and first presented with generalized loss of adipose tissue and insulin-resistant diabetes. CRISPR-Cas9-mediated TP KO in ASC abolished adipocyte differentiation and decreased insulin response, consistent with the patients' phenotype. This KO also induced major oxidative stress, altered mitochondrial functions, and promoted cellular senescence. This translational study identifies a new role of TP by demonstrating its key regulatory functions in adipose tissue.

CONCLUSIONS

The implication of TP variants in atypical forms of monogenic diabetes shows that genetic diagnosis of lipodystrophic syndromes should include TYMP analysis. The fact that TP is crucial for adipocyte differentiation and function through the control of mitochondrial homeostasis highlights the importance of mitochondria in adipose tissue biology.

Interleukins in adipose tissue: Keeping the balance

The role of the immune system is to defend the host and preserve the functionality in response to stress. This function is not limited to infection or injury as it also plays a role in the response to overnutrition. Indeed, low-grade chronic activation of the immune system associated with overnutrition may be deleterious, contributing importantly to diabetes and long-term complications, such as cardiovascular disorders. Increasing evidence shows that adipose tissue participates in the obesity-related inflammatory response and that interleukins are one of the key players, either as a pro-inflammatory response to the metabolic dysregulation or to restore homeostasis. The crosstalk between adipocytes and immune cells through some important interleukins and their role in metabolic disruption is the topic of this review.

Nitric Oxide Synthase activity in major depressive episodes before and after antidepressant treatment: Results of a large case-control treatment study

BACKGROUND

Nitric oxide synthase (NOS) activity, an enzyme potentially involved in the major depressive episodes (MDE), could be indirectly measured by the L-Citrulline/L-Arginine ratio (L-Cit/L-Arg). The aim of this study was: (1) to compare the NOS activity of patients with a MDE to that of healthy controls (HC); (2) to assess its change after antidepressant treatment.

METHODS

A total of 460 patients with a current MDE in a context of major depressive disorder (MDD) were compared to 895 HC for NOS activity (L-Cit/L-Arg plasma ratio). L-Arg and L-Cit plasma levels were measured using a MS-based liquid chromatography method. Depressed patients were assessed at baseline, and after 3 and 6 months of antidepressant treatment for depression severity and clinical response.

RESULTS

Depressed patients had a lower NOS activity than HC at baseline [0.31 ± 0.09 v. 0.38 ± 0.12; 95% confidence interval (CI) -0.084 to -0.062, p < 0.0001]. Lower NOS activity at baseline predicted a higher response rate [odds ratio (OR) = 29.20; 95% CI 1.58-536.37; p = 0.023]. NOS activity in depressed patients increased significantly up to 0.34 ± 0.08 after antidepressant treatment (Est = 0.0034; 95% CI 0.0002-0.0067; p = 0.03).

CONCLUSIONS

Depressed patients have a decreased NOS activity that improves after antidepressant treatment and predicts drug response. NOS activity may be a promising biomarker for MDE in a context of MDD.

Epicardial and Pericardial Adiposity Without Myocardial Steatosis in Cushing Syndrome

CONTEXT

Cardiovascular disease is the leading cause of death in patients with Cushing syndrome. Cortisol excess and adverse metabolic profile could increase cardiac fat, which can subsequently impair cardiac structure and function.

OBJECTIVE

We aimed to evaluate cardiac fat mass and distribution in patients with Cushing syndrome.

METHODS

In this prospective, cross-sectional study, 23 patients with Cushing syndrome and 27 control individuals of comparable age, sex, and body mass index were investigated by cardiac magnetic resonance imaging and proton spectroscopy. Patients were explored before and after biochemical disease remission. Myocardial fat measured by the Dixon method was the main outcome measure. The intramyocardial triglyceride/water ratio measured by spectroscopy and epicardial and pericardial fat volumes were secondary outcome measures.

RESULTS

No difference was found between patients and controls in intramyocardial lipid content. Epicardial fat mass was increased in patients compared to controls (30.8 g/m2 [20.4-34.8] vs 17.2 g/m2 [13.1-23.5], P < .001). Similarly, pericardial fat mass was increased in patients compared to controls (28.3 g/m2 [17.9-38.0] vs 11.4 g/m2 [7.5-19.4], P = .003). Sex, glycated hemoglobin A1c, and the presence of hypercortisolism were independent determinants of epicardial fat. Pericardial fat was associated with sex, impaired glucose homeostasis and left ventricular wall thickness. Disease remission decreased epicardial fat mass without affecting pericardial fat.

CONCLUSION

Intramyocardial fat stores are not increased in patients with Cushing syndrome, despite highly prevalent metabolic syndrome, suggesting increased cortisol-mediated lipid consumption. Cushing syndrome is associated with marked accumulation of epicardial and pericardial fat. Epicardial adiposity may exert paracrine proinflammatory effects promoting cardiomyopathy.

Biallelic CAV1 null variants induce congenital generalized lipodystrophy with achalasia

OBJECTIVE

CAV1 encodes caveolin-1, a major protein of plasma membrane microdomains called caveolae, involved in several signaling pathways. Caveolin-1 is also located at the adipocyte lipid droplet. Heterozygous pathogenic variants of CAV1 induce rare heterogeneous disorders including pulmonary arterial hypertension and neonatal progeroid syndrome. Only one patient was previously reported with a CAV1 homozygous pathogenic variant, associated with congenital generalized lipodystrophy (CGL3). We aimed to further delineate genetic transmission, clinical, metabolic, and cellular characteristics of CGL3.

DESIGN/METHODS

In a large consanguineous kindred referred for CGL, we performed next-generation sequencing, as well as clinical, imagery, and metabolic investigations. We studied skin fibroblasts from the index case and the previously reported patient with CGL3.

RESULTS

Four patients, aged 8 months to 18 years, carried a new homozygous p.(His79Glnfs*3) CAV1 variant. They all displayed generalized lipodystrophy since infancy, insulin resistance, low HDL-cholesterol, and/or high triglycerides, but no pulmonary hypertension. Two patients also presented at the age of 15 and 18 years with dysphagia due to achalasia, and one patient had retinitis pigmentosa. Heterozygous parents and relatives (n = 9) were asymptomatic, without any metabolic abnormality. Patients' fibroblasts showed a complete loss of caveolae and no protein expression of caveolin-1 and its caveolin-2 and cavin-1 partners. Patients' fibroblasts also displayed insulin resistance, increased oxidative stress, and premature senescence.

CONCLUSIONS

The CAV1 null variant investigated herein leads to an autosomal recessive congenital lipodystrophy syndrome. Loss of caveolin-1 and/or caveolae induces specific manifestations including achalasia which requires specific management. Overlapping phenotypic traits between the different CAV1-related diseases require further studies.

Metformin alleviates stress-induced cellular senescence of aging human adipose stromal cells and the ensuing adipocyte dysfunction

Aging is associated with central fat redistribution and insulin resistance. To identify age-related adipose features, we evaluated the senescence and adipogenic potential of adipose-derived stromal cells (ASCs) from abdominal subcutaneous fat obtained from healthy normal-weight young (<25 years) or older women (>60 years). Increased cell passages of young-donor ASCs (in vitro aging) resulted in senescence but not oxidative stress. ASC-derived adipocytes presented impaired adipogenesis but no early mitochondrial dysfunction. Conversely, aged-donor ASCs at early passages displayed oxidative stress and mild senescence. ASC-derived adipocytes exhibited oxidative stress, and early mitochondrial dysfunction but adipogenesis was preserved. In vitro aging of aged-donor ASCs resulted in further increased senescence, mitochondrial dysfunction, oxidative stress, and severe adipocyte dysfunction. When in vitro aged young-donor ASCs were treated with metformin, no alteration was alleviated. Conversely, metformin treatment of aged-donor ASCs decreased oxidative stress and mitochondrial dysfunction resulting in decreased senescence. Metformin's prevention of oxidative stress and of the resulting senescence improved the cells' adipogenic capacity and insulin sensitivity. This effect was mediated by the activation of AMP-activated protein kinase as revealed by its specific inhibition and activation. Overall, aging ASC-derived adipocytes presented impaired adipogenesis and insulin sensitivity. Targeting stress-induced senescence of ASCs with metformin may improve age-related adipose tissue dysfunction.

Diabetes Increases Severe COVID-19 Outcomes Primarily in Younger Adults

CONTEXT

Diabetes is reported as a risk factor for severe coronavirus disease 2019 (COVID-19), but whether this risk is similar in all categories of age remains unclear.

OBJECTIVE

To investigate the risk of severe COVID-19 outcomes in hospitalized patients with and without diabetes according to age categories.

DESIGN SETTING AND PARTICIPANTS

We conducted a retrospective observational cohort study of 6314 consecutive patients hospitalized for COVID-19 between February and 30 June 2020 in the Paris metropolitan area, France; follow-up was recorded until 30 September 2020.

MAIN OUTCOME MEASURE(S)

The main outcome was a composite outcome of mortality and orotracheal intubation in subjects with diabetes compared with subjects without diabetes, after adjustment for confounding variables and according to age categories.

RESULTS

Diabetes was recorded in 39% of subjects. Main outcome was higher in patients with diabetes, independently of confounding variables (hazard ratio [HR] 1.13 [1.03-1.24]) and increased with age in individuals without diabetes, from 23% for those <50 to 35% for those >80 years but reached a plateau after 70 years in those with diabetes. In direct comparison between patients with and without diabetes, diabetes-associated risk was inversely proportional to age, highest in <50 years and similar after 70 years. Similarly, mortality was higher in patients with diabetes (26%) than in those without diabetes (22%, P < 0.001), but adjusted HR for diabetes was significant only in patients younger than age 50 years (HR 1.81 [1.14-2.87]).

CONCLUSIONS

Diabetes should be considered as an independent risk factor for the severity of COVID-19 in young adults more so than in older adults, especially for individuals younger than 70 years.

EPHX1 mutations cause a lipoatrophic diabetes syndrome due to impaired epoxide hydrolysis and increased cellular senescence

Epoxide hydrolases (EHs) regulate cellular homeostasis through hydrolysis of epoxides to less-reactive diols. The first discovered EH was EPHX1, also known as mEH. EH functions remain partly unknown, and no pathogenic variants have been reported in humans. We identified two de novo variants located in EPHX1 catalytic site in patients with a lipoatrophic diabetes characterized by loss of adipose tissue, insulin resistance, and multiple organ dysfunction. Functional analyses revealed that these variants led to the protein aggregation within the endoplasmic reticulum and to a loss of its hydrolysis activity. CRISPR-Cas9-mediated EPHX1 knockout (KO) abolished adipocyte differentiation and decreased insulin response. This KO also promoted oxidative stress and cellular senescence, an observation confirmed in patient-derived fibroblasts. Metreleptin therapy had a beneficial effect in one patient. This translational study highlights the importance of epoxide regulation for adipocyte function and provides new insights into the physiological roles of EHs in humans.

Altered subcutaneous adipose tissue parameters after switching ART-controlled HIV+ patients to raltegravir/maraviroc

OBJECTIVE

To evaluate the effect on anthropometric, metabolic and adipose tissue parameters of switching ART-controlled persons living with HIV (PLWH) from a protease inhibitor regimen to raltegravir/maraviroc.

DESIGN

Sub-study of the ANRS157 ROCnRAL study with the investigation of subcutaneous abdominal adipose tissue (SCAT) biopsy at inclusion and study end.

METHODS

We performed lipoaspiration of paired SCAT samples, histology on fresh/fixed samples and examined the transcriptomic profile analyzed using Illumina microarrays after RNA extraction. Statistical analyses used the Wilcoxon-paired test.

RESULTS

The patients (n = 8) were mainly male (7/8), aged (mean ± standard error of the mean) 54.9 ± 1.2 years, BMI 26.1 ± 1.2 kg/m2, CD4+ 699 ± 56 cells/mm3, all viral load (VL) <50 copies/ml. After a follow-up of 6 ± 0.5 months, all PLWH remained with VL <50 copies/ml. BMI, trunk and limb fat amounts were unchanged yet systemic insulin resistance increased. Adipose tissue histology was unchanged except for borderline increased adipocyte diameter (P = 0.1). Among the 16 094 RNA transcripts, 458 genes were up-regulated and 244 were down-regulated. Analyses of the Kyoto Encyclopedia of Genes and Genomes and Gene Ontology databases, evaluating modifications in the main functional pathways, revealed that genes related to immune recognition/function were less expressed as were genes encoding T-cell receptor and receptor signaling pathways. The gene expression profiles indicated decreased inflammation but genes involved in adipogenesis and insulin resistance were overexpressed.

CONCLUSION

After 6 months of raltegravir/maraviroc, adipogenesis-related gene profile was enhanced in SCAT, in agreement with a tendency for increased adipocyte size. Enhanced SCAT insulin resistance-related profile was concordant with higher systemic insulin resistance. However, the immune activation/inflammation profile was globally lowered. We propose that raltegravir/maraviroc might favor SCAT gain but reduce inflammation/immune activation.

Sex disparities in COVID-19 outcomes of inpatients with diabetes: insights from the CORONADO study

OBJECTIVE

Male sex is one of the determinants of severe coronavirus diseas-e-2019 (COVID-19). We aimed to characterize sex differences in severe outcomes in adults with diabetes hospitalized for COVID-19.

METHODS

We performed a sex-stratified analysis of clinical and biological features and outcomes (i.e. invasive mechanical ventilation (IMV), death, intensive care unit (ICU) admission and home discharge at day 7 (D7) or day 28 (D28)) in 2380 patients with diabetes hospitalized for COVID-19 and included in the nationwide CORONADO observational study (NCT04324736).

RESULTS

The study population was predominantly male (63.5%). After multiple adjustments, female sex was negatively associated with the primary outcome (IMV and/or death, OR: 0.66 (0.49-0.88)), death (OR: 0.49 (0.30-0.79)) and ICU admission (OR: 0.57 (0.43-0.77)) at D7 but only with ICU admission (OR: 0.58 (0.43-0.77)) at D28. Older age and a history of microvascular complications were predictors of death at D28 in both sexes, while chronic obstructive pulmonary disease (COPD) was predictive of death in women only. At admission, C-reactive protein (CRP), aspartate amino transferase (AST) and estimated glomerular filtration rate (eGFR), according to the CKD-EPI formula predicted death in both sexes. Lymphocytopenia was an independent predictor of death in women only, while thrombocytopenia and elevated plasma glucose concentration were predictors of death in men only.

CONCLUSIONS

In patients with diabetes admitted for COVID-19, female sex was associated with lower incidence of early severe outcomes, but did not influence the overall in-hospital mortality, suggesting that diabetes mitigates the female protection from COVID-19 severity. Sex-associated biological determinants may be useful to optimize COVID-19 prevention and management in women and men.

Recent data on adipose tissue, insulin resistance, diabetes and dyslipidaemia in antiretroviral therapy controlled HIV-infected persons

PURPOSE OF REVIEW

Increased total body fat with truncal redistribution is common in antiretroviral therapy (ART)-controlled persons living with HIV(PLWH), leading to insulin resistance, prediabetes/diabetes and dyslipidaemia. We address these topics here.

RECENT FINDINGS

Most antiretrovirals are associated with gain in trunk fat, including visceral adipose tissue (VAT). Protease-inhibitors could inhibit white fat ability to dissipate energy (i.e. beiging) favouring fat gain. Expansion of VAT is associated with a pro-inflammatory profile linked to the tryptophan-kynurenine pathway and CD4+ subtypes. ART-associated increased adipose tissue (AT) quantity leads to decreased AT density, insulin resistance and dyslipidaemia that could be improved by lifestyle modifications.PLWH present high level of insulin resistance, regardless of their treatment, and a higher prevalence of prediabetes, but not diabetes, than noninfected persons. Otherwise, HbA1c values appear inaccurate to diagnose prediabetes/diabetes in PLWH.ART-related-dyslipidaemia is characterized by elevated LDL-C and/or high triglycerides and reduced HDL-C. Whereas treatment with protease inhibitors generally results in worsened lipid values, treatment with integrase-strand-transfer-inhibitors is associated with a better profile. Tenofovir-alafenamide is associated with higher lipid levels than tenofovir-disoproxil-fumarate. Treatment of LDL-C-dyslipidaemia could benefit, in statin-insufficiently controlled patients, from the class of proprotein-convertase-subtilsin-kenin-type-9 (PCSK-9) inhibitors.

SUMMARY

Lifestyle modifications are mandatory to reduce fat and improve dysglycaemia/dyslipidaemia. New drugs can efficiently control diabetes and LDL-C-dyslipidaemia.

The Integrase Inhibitors Dolutegravir and Raltegravir Exert Proadipogenic and Profibrotic Effects and Induce Insulin Resistance in Human/Simian Adipose Tissue and Human Adipocytes

BACKGROUND

Although some integrase strand transfer inhibitors (INSTIs) promote peripheral and central adipose tissue/weight gain in people with human immunodeficiency virus (PHIV), the underlying mechanism has not been identified. Here, we used human and simian models to assess the impact of INSTIs on adipose tissue phenotype and function.

METHODS

Adipocyte size and fibrosis were determined in biopsies of subcutaneous and visceral adipose tissue (SCAT and VAT, respectively) from 14 noninfected macaques and 19 PHIV treated or not treated with an INSTI. Fibrosis, adipogenesis, oxidative stress, mitochondrial function, and insulin sensitivity were assessed in human proliferating or adipocyte-differentiated adipose stem cells after long-term exposure to dolutegravir or raltegravir.

RESULTS

We observed elevated fibrosis, adipocyte size, and adipogenic marker expression in SCAT and VAT from INSTI-treated noninfected macaques. Adiponectin expression was low in SCAT. Accordingly, SCAT and VAT samples from INSTI-exposed patients displayed higher levels of fibrosis than those from nonexposed patients. In vitro, dolutegravir and, to a lesser extent, raltegravir were associated with greater extracellular matrix production and lipid accumulation in adipose stem cells and/or adipocytes as observed in vivo. Despite the INSTIs' proadipogenic and prolipogenic effects, these drugs promoted oxidative stress, mitochondrial dysfunction, and insulin resistance.

CONCLUSIONS

Dolutegravir and raltegravir can directly impact adipocytes and adipose tissue. These INSTIs induced adipogenesis, lipogenesis, oxidative stress, fibrosis, and insulin resistance. The present study is the first to shed light on the fat modifications observed in INSTI-treated PHIV.

The Goto-Kakizaki rat is a spontaneous prototypical rodent model of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is characterized by an oligo-anovulation, hyperandrogenism and polycystic ovarian morphology combined with major metabolic disturbances. However, despite the high prevalence and the human and economic consequences of this syndrome, its etiology remains unknown. In this study, we show that female Goto-Kakizaki (GK) rats, a type 2 diabetes mellitus model, encapsulate naturally all the reproductive and metabolic hallmarks of lean women with PCOS at puberty and in adulthood. The analysis of their gestation and of their fetuses demonstrates that this PCOS-like phenotype is developmentally programmed. GK rats also develop features of ovarian hyperstimulation syndrome. Lastly, a comparison between GK rats and a cohort of women with PCOS reveals a similar reproductive signature. Thus, this spontaneous rodent model of PCOS represents an original tool for the identification of the mechanisms involved in its pathogenesis and for the development of novel strategies for its treatment.

Pharmacological modulation of RORα controls fat browning, adaptive thermogenesis, and body weight in mice

Beiging is an attractive therapeutic strategy to fight against obesity and its side metabolic complications. The loss of function of the nuclear transcription factor RORα has been related to a lean phenotype with higher thermogenesis in sg/sg mice lacking this protein. Here we show that pharmacological modulation of RORα activity exerts reciprocal and cell-autonomous effect on UCP1 expression ex vivo, in cellulo, and in vivo. The RORα inverse-agonist SR3335 upregulated UCP1 expression in brown and subcutaneous white adipose tissue (scWAT) explants of wild-type (WT) mice, whereas the RORα agonist SR1078 had the opposite effect. We confirmed the reciprocal action of these synthetic RORα ligands on gene expression, mitochondrial mass, and uncoupled oxygen consumption rate in cultured murine and human adipocytes. Time course analysis revealed stepwise variation in gene expression, first of TLE3, an inhibitor of the thermogenic program, followed by a reciprocal effect on PRDM16 and UCP1. Finally, RORα ligands were shown to be useful tools to modulate in vivo UCP1 expression in scWAT with associated changes in this fat depot mass. SR3335 and SR1078 provoked the opposite effects on the WT mice body weight, but without any effect on sg/sg mice. This slimming effect of SR3335 was related to an increased adaptive thermogenesis of the mice, as assessed by the rectal temperature of cold-stressed mice and induction of UCP1 in scWAT, as well as by indirect calorimetry in presence or not of a β3-adrenoceptor agonist. These data confirmed that RORα ligands could be useful tools to modulate thermogenesis and energy homeostasis.NEW & NOTEWORTHY The regulation of adipose tissue browning was not fully deciphered and required further studies explaining how the regulation of this process may be of interest for tackling obesity and related metabolic disorders. Our data confirmed the involvement of the transcription factor RORα in the regulation of nonshivering thermogenesis, and importantly, revealed the possibility to in vivo modulate its activity by synthetic ligands with beneficial consequences on fat mass and body weight of the mice.

Molecular and Cellular Bases of Lipodystrophy Syndromes

Lipodystrophy syndromes are rare diseases originating from a generalized or partial loss of adipose tissue. Adipose tissue dysfunction results from heterogeneous genetic or acquired causes, but leads to similar metabolic complications with insulin resistance, diabetes, hypertriglyceridemia, nonalcoholic fatty liver disease, dysfunctions of the gonadotropic axis and endocrine defects of adipose tissue with leptin and adiponectin deficiency. Diagnosis, based on clinical and metabolic investigations, and on genetic analyses, is of major importance to adapt medical care and genetic counseling. Molecular and cellular bases of these syndromes involve, among others, altered adipocyte differentiation, structure and/or regulation of the adipocyte lipid droplet, and/or premature cellular senescence. Lipodystrophy syndromes frequently present as systemic diseases with multi-tissue involvement. After an update on the main molecular bases and clinical forms of lipodystrophy, we will focus on topics that have recently emerged in the field. We will discuss the links between lipodystrophy and premature ageing and/or immuno-inflammatory aggressions of adipose tissue, as well as the relationships between lipomatosis and lipodystrophy. Finally, the indications of substitutive therapy with metreleptin, an analog of leptin, which is approved in Europe and USA, will be discussed.

Glucocorticoids impair HDL-mediated cholesterol efflux besides increased HDL cholesterol concentration: a proof of concept

OBJECTIVE

Glucocorticoids (GC) are associated with increased cardiovascular morbidity despite increased HDL-C concentration. HDL-mediated cholesterol efflux, a major anti-atherogenic property of HDL particles, is negatively associated with CVD risk. We aimed to determine whether HDL-mediated cholesterol efflux was influenced by GC.

DESIGN

Prospective, observational study.

METHODS

Lipid parameters, HDL composition, HDL-mediated cholesterol efflux, cholesteryl ester transfer protein, phospholipid transfer protein and lecithin cholesterol acyl-transferase (LCAT) activities were determined in ten patients with giant cell arteritis before and 3 months after GC introduction and in seven control subjects. HDL concentration and composition, HDL-mediated cholesterol efflux and LCAT activity were determined in GC-treated mice.

RESULTS

In patients, HDL-C concentration was higher after than before treatment GC-treatment (P = 0.002), while HDL-mediated cholesterol efflux was decreased (P = 0.008) and negatively associated with the proportion of cholesteryl ester in HDL (P = 0.04), independently of CRP. As well, in mice, HDL-C level was increased after GC exposure (P = 0.04) and HDL-mediated cholesterol efflux decreased (P = 0.04). GC-treated patients had higher cholesteryl ester content in HDL, higher HDL2-to-HDL3 ratio and higher LCAT activity than before treatment (P = 0.008, P = 0.02 and P = 0.004, respectively).

CONCLUSIONS

We report, for the first time, that in patients with giant cell arteritis and mice treated with GC, HDL-mediated cholesterol efflux was impaired by GC besides an increased HDL-C level. This impaired HDL functionality, possibly related to HDL enrichment in cholesteryl ester, could contribute to the increased CVD risk observed in GC-treated patients. Further studies are needed in larger populations, to further decipher the effect of GC on HDL.

SIV Infection and the HIV Proteins Tat and Nef Induce Senescence in Adipose Tissue and Human Adipose Stem Cells, Resulting in Adipocyte Dysfunction

Background: Aging is characterized by adipose tissue senescence, inflammation, and fibrosis, with trunk fat accumulation. Aging HIV-infected patients have a higher risk of trunk fat accumulation than uninfected individuals—suggesting that viral infection has a role in adipose tissue aging. We previously demonstrated that HIV/SIV infection and the Tat and Nef viral proteins were responsible for adipose tissue fibrosis and impaired adipogenesis. We hypothesized that SIV/HIV infection and viral proteins could induce adipose tissue senescence and thus lead to adipocyte dysfunctions. Methods: Features of tissue senescence were evaluated in subcutaneous and visceral adipose tissues of SIV-infected macaques and in human adipose stem cells (ASCs) exposed to Tat or Nef for up to 30 days. Results: p16 expression and p53 activation were higher in adipose tissue of SIV-infected macaques than in control macaques, indicating adipose tissue senescence. Tat and Nef induced higher senescence in ASCs, characterized by higher levels of senescence-associated beta-galactosidase activity, p16 expression, and p53 activation vs. control cells. Treatment with Tat and Nef also induced oxidative stress and mitochondrial dysfunction. Prevention of oxidative stress (using N-acetyl-cysteine) reduced senescence in ASCs. Adipocytes having differentiated from Nef-treated ASCs displayed alterations in adipogenesis with lower levels of triglyceride accumulation and adipocyte marker expression and secretion, and insulin resistance. Conclusion: HIV/SIV promotes adipose tissue senescence, which in turn may alter adipocyte function and contribute to insulin resistance.

Lower plasma vascular endothelial growth factor A in major depressive disorder not normalized after antidepressant treatment: A case control study

OBJECTIVE

Vascular endothelial growth factor A is a growth factor with pro-angiogenic and neurotrophic properties. Anti-vascular endothelial growth factor A treatments, used to treat cancers and opthalmic diseases, are known to induce depressive symptoms. Thus, we hypothesized that vascular endothelial growth factor A plasma levels are low in patients experiencing a major depressive episode in the context of major depressive disorder, which consequently increase after antidepressant treatment. The aim of this study was to compare plasma vascular endothelial growth factor A levels in patients with major depressive episode-major depressive disorder before and after antidepressant treatment.

METHODS

Vascular endothelial growth factor A fasting plasma levels of 469 major depressive episode-major depressive disorder patients were compared with healthy controls. Depressed patients were assessed for remission after 3 and 6 months of antidepressant treatment. Bivariate and multivariate analyses adjusted for sex, age, body mass index and tobacco use were performed.

RESULTS

As compared to healthy controls, major depressive episode patients had lower vascular endothelial growth factor A, 66.0 (38.3) pg/mL (standard deviation) vs 83.2 (49.2) pg/mL, p < 0.0001. Plasma vascular endothelial growth factor A levels did not change after antidepressant treatment, even in remitters, and remained lower than those of healthy controls, 64.9 (39.3) pg/mL vs 83.2 (49.2) pg/mL, p < 0.0001.

CONCLUSION

Depressed patients with major depressive disorder have lower plasma vascular endothelial growth factor A levels than healthy controls during their major depressive episode and after remission following antidepressant treatment. New strategies targeting enhancement of plasma vascular endothelial growth factor A could be promising for the prevention and treatment of major depressive disorder.

Severe insomnia is associated with metabolic syndrome in women over 50 years with major depression treated in psychiatry settings: a METADAP report

INTRODUCTION

Major depression is associated with metabolic syndrome and cardiovascular risk. We have previously shown that severe insomnia, a core symptom of major depression episode (MDE), is associated with hypertriglyceridemia, a component of metabolic syndrome, in women but not in men with major depression. Since insomnia is related to cardiovascular morbidity in the general population and major depression also, our objective was to assess the link between insomnia and metabolic syndrome, a marker syndrome of cardiovascular risk, during MDE, in women and in men.

METHODS

In 624 patients with a current MDE cohort, both insomnia and metabolic syndrome were assessed in women and men. Insomnia was rated from 0 to 6 based on the HDRS corresponding items, severe insomnia being defined by a total insomnia score ≥4.

RESULTS

severe insomnia was associated with metabolic syndrome in women but not in men. In multivariate logistic regressions, these results in women were independent from age, educational level, major depressive disorder duration and current smoking. These results were only significant in women aged ≥50 years, a cut-off age for menopausal status but not in women under 50 years.

CONCLUSION

Women aged ≥50 years with a severe insomnia during MDE have an increased risk of metabolic syndrome. Severe insomnia may be a clinical marker of metabolic risk in this population. They should be particularly monitored for metabolic syndrome and may benefit from sleep recommendations and cardiovascular prevention.

Peripheral tryptophan, serotonin, kynurenine, and their metabolites in major depression: A case-control study

AIM

Tryptophan is the sole precursor of both peripherally and centrally produced serotonin and kynurenine. In depressed patients, tryptophan, serotonin, kynurenine, and their metabolite levels remain unclear. Therefore, peripheral tryptophan and metabolites of serotonin and kynurenine were investigated extensively in 173 patients suffering from a current major depressive episode (MDE) and compared to 214 healthy controls (HC).

METHODS

Fasting plasma levels of 11 peripheral metabolites were quantified: tryptophan, serotonin pathway (serotonin, its precursor 5-hydroxytryptophan and its metabolite 5-hydroxyindoleacetic acid), and kynurenine pathway (kynurenine and six of its metabolites: anthranilic acid, kynurenic acid, nicotinamide, picolinic acid, xanthurenic acid, and 3-hydroxyanthranilic acid).

RESULTS

Sixty (34.7%) patients were antidepressant-drug free. Tryptophan levels did not differ between MDE patients and HC. Serotonin and its precursor (5-hydroxytryptophan) levels were lower in MDE patients than in HC, whereas, its metabolite (5-hydroxyindoleacetic acid) levels were within the standard range. Kynurenine and four of its metabolites (kynurenic acid, nicotinamide, picolinic acid, and xanthurenic acid) were lower in MDE patients.

CONCLUSION

Whilst the results of this study demonstrate an association between the metabolites studied and depression, conclusions about causality cannot be made. This study uses the largest ever sample of MDE patients, with an extensive assessment of peripheral tryptophan metabolism in plasma. These findings provide new insights into the peripheral signature of MDE. The reasons for these changes should be further investigated. These results might suggest new antidepressant therapeutic strategies.

Relationships between metabolic status, seminal adipokines, and reproductive functions in men from infertile couples

OBJECTIVE

Adipokines could be a link between metabolic syndrome (MS) and infertility. While the association between circulating adipokines and fertility has been extensively studied in females, this relationship in males was less investigated, although some adipokines are detectable in seminal plasma (SP). The aim of this study was to determine adipokine levels in blood and SP and to assess the relationships between adipokines, MS and semen parameters in men from infertile couples.

DESIGN

Male partners of infertile couples referred to four medical French centers were enrolled in years 2013-2016.

METHODS

Subjects (n = 160) aged 18-45 years were assessed for anthropometric, biochemical, sperm, and circulating hormonal parameters. Leptin, adiponectin, resistin, chemerin, visfatin, and IL-6 were measured in serum and SP.

RESULTS

Infertility duration was higher in men with than without MS. Adipokine concentrations were higher in blood than in SP, except for IL-6 and visfatin. The most striking result was the significant correlation observed between seminal IL-6 and spermatozoid concentration, progressive motility, and sperm vitality. Moreover, while men with MS exhibited an expected lower adiponectinemia, they displayed 2.1-fold higher adiponectin levels in SP than men without MS. Finally, logistic regression analysis showed that BMI, infertility duration, and adiponectin serum/SP ratio were independently associated with MS.

CONCLUSIONS

These results suggest an involvement of seminal adipokines to modulate fertility in men with MS and that seminal IL-6 could play a beneficial role on sperm functionality. Further mechanistic studies are necessary to investigate the precise roles of these adipokines in male reproduction.

Human Dermal Fibroblast: A Promising Cellular Model to Study Biological Mechanisms of Major Depression and Antidepressant Drug Response

BACKGROUND

Human dermal fibroblasts (HDF) can be used as a cellular model relatively easily and without genetic engineering. Therefore, HDF represent an interesting tool to study several human diseases including psychiatric disorders. Despite major depressive disorder (MDD) being the second cause of disability in the world, the efficacy of antidepressant drug (AD) treatment is not sufficient and the underlying mechanisms of MDD and the mechanisms of action of AD are poorly understood.

OBJECTIVE

The aim of this review is to highlight the potential of HDF in the study of cellular mechanisms involved in MDD pathophysiology and in the action of AD response.

METHODS

The first part is a systematic review following PRISMA guidelines on the use of HDF in MDD research. The second part reports the mechanisms and molecules both present in HDF and relevant regarding MDD pathophysiology and AD mechanisms of action.

RESULTS

HDFs from MDD patients have been investigated in a relatively small number of works and most of them focused on the adrenergic pathway and metabolism-related gene expression as compared to HDF from healthy controls. The second part listed an important number of papers demonstrating the presence of many molecular processes in HDF, involved in MDD and AD mechanisms of action.

CONCLUSION

The imbalance in the number of papers between the two parts highlights the great and still underused potential of HDF, which stands out as a very promising tool in our understanding of MDD and AD mechanisms of action.

Lipodystrophic syndromes: From diagnosis to treatment

Lipodystrophic syndromes are acquired or genetic rare diseases, characterised by a generalised or partial lack of adipose tissue leading to metabolic alterations linked to strong insulin resistance. They encompass a variety of clinical entities due to primary defects in adipose differentiation, in the structure and/or regulation of the adipocyte lipid droplet, or due to immune-inflammatory aggressions, chromatin deregulations and/or mitochondrial dysfunctions affecting adipose tissue. Diagnosis is based on clinical examination, pathological context and comorbidities, and on results of metabolic investigations and genetic analyses, which together determine management and genetic counselling. Early lifestyle and dietary measures focusing on regular physical activity and avoiding excess energy intake are crucial. They are accompanied by multidisciplinary follow-up adapted to each clinical form. In case of hyperglycemia, antidiabetic medications, with metformin as a first-line therapy in adults, are used in addition to lifestyle and dietary modifications. When standard treatments have failed to control metabolic disorders, the orphan drug metreleptin, an analog of leptin, can be effective in certain forms of lipodystrophy syndrome. Metreleptin therapy indications, prescription and monitoring were recently defined in France, representing a major improvement in patient care.

Systemic Dysfunction of Osteoblast Differentiation in Adipose-Derived Stem Cells from Patients with Multiple Myeloma

Multiple myeloma is characterized by bone lesions linked to increased osteoclast and decreased osteoblast activities. In particular, the osteoblast differentiation of bone marrow-derived stem cells (MSC) is impaired. Among the potential therapeutic tools for counteracting bone lesions, adipose-derived stem cells (ASC) could represent an appealing source for regenerative medicine due to their similar characteristics with MSC. Our study is among the first giving detailed insights into the osteoblastogenic capacities of ASC isolated by fat aspiration from myeloma patients (MM-ASC) compared to healthy subjects (HD-ASC). We showed that MM-ASC and HD-ASC exhibited comparable morphology, proliferative capacity, and immunophenotype. Unexpectedly, although normal in adipocyte differentiation, MM-ASC present a defective osteoblast differentiation, as indicated by less calcium deposition, decreased alkaline phosphatase activity, and downregulation of RUNX2 and osteocalcin. Furthermore, these ASC-derived osteoblasts displayed enhanced senescence, as shown by an increased β-galactosidase activity and cell cycle inhibitors expression (p16^INK4A, p21^WAF1/CIP1.), associated with a markedly increased expression of DKK1, a major inhibitor of osteoblastogenesis in multiple myeloma. Interestingly, inhibition of DKK1 attenuated senescence and rescued osteoblast differentiation, highlighting its key role. Our findings show, for the first time, that multiple myeloma is a systemic disease and suggest that ASC from patients would be unsuitable for tissue engineering designed to treat myeloma-associated bone disease.

Monogenic forms of lipodystrophic syndromes: diagnosis, detection, and practical management considerations from clinical cases

BACKGROUND

Lipodystrophic syndromes are rare diseases of genetic or acquired origin characterized by partial or generalized lack of body fat. Early detection and diagnosis are crucial to prevent and manage associated metabolic dysfunctions, i.e. insulin resistance, dyslipidemia, fatty liver, and diabetes, and to provide appropriate genetic counseling. By means of several representative case studies, this article illustrates the diagnostic and management challenges of lipodystrophic syndromes.

REVIEW

Berardinelli-Seip congenital lipodystrophy (BSCL) is typically diagnosed at birth, or soon thereafter, with generalized lipoatrophy and hepatomegaly secondary to hepatic steatosis. Physicians must also consider this diagnosis in adults with atypical non-autoimmune diabetes, hypertriglyceridemia, and a lean and muscular phenotype. The BSCL1 subtype due to mutations in the AGPAT2 gene can have an unusual presentation, especially in neonates and infants. Particular attention should be paid to infants presenting failure to thrive who also have hepatomegaly and metabolic derangements. The BSCL2 sub-type due to mutations in the BSCL gene tends to be more severe than BSCL1, and is characterized by greater fat loss, mild intellectual disability, earlier onset of diabetes, and higher incidence of premature death. Effective management from an earlier age may moderate the natural disease course. Partial lipodystrophies may easily be confused with common central obesity and/or metabolic syndrome. In patients with unexplained pancreatitis and hypertriglyceridemia, lipodystrophies such as familial partial lipodystrophy type 2 (FPLD2; Dunnigan type, due to LMNA mutations) should be considered. Oral combined contraceptives, which can reveal the disease by inducing severe hypertriglyceridemia, are contraindicated. Endogenous estrogens may also lead to "unmasking" of the FPLD2 phenotype, which often appears at puberty, and is more severe in females than males.

CONCLUSIONS

Diet and exercise, adapted to age and potential comorbidities, are essential prerequisites for therapeutic management of lipodystrophic syndromes. Metreleptin therapy can be useful to manage lipodystrophy-related metabolic complications.

Adipocyte Glucocorticoid Receptor Deficiency Promotes Adipose Tissue Expandability and Improves the Metabolic Profile Under Corticosterone Exposure

Widely used for their anti-inflammatory and immunosuppressive properties, glucocorticoids are nonetheless responsible for the development of diabetes and lipodystrophy. Despite an increasing number of studies focused on the adipocyte glucocorticoid receptor (GR), its precise role in the molecular mechanisms of these complications has not been elucidated. In keeping with this goal, we generated a conditional adipocyte-specific murine model of GR invalidation (AdipoGR knockout [KO] mice). Interestingly, when administered a corticosterone treatment to mimic hypercorticism conditions, AdipoGR-KO mice exhibited an improved glucose tolerance and insulin sensitivity. This was related to the adipose-specific activation of the insulin-signaling pathway, which contributed to fat mass expansion, as well as a shift toward an anti-inflammatory macrophage polarization in adipose tissue of AdipoGR-KO animals. Moreover, these mice were protected against ectopic lipid accumulation in the liver and displayed an improved lipid profile, contributing to their overall healthier phenotype. Altogether, our results indicate that adipocyte GR is a key factor of adipose tissue expansion and glucose and lipid metabolism control, which should be taken into account in the further design of adipocyte GR-selective modulators.

Adaptive β-Cell Neogenesis in the Adult Mouse in Response to Glucocorticoid-Induced Insulin Resistance

Both type 1 and type 2 diabetes are characterized by deficient insulin secretion and decreased β-cell mass. Thus, regenerative strategies to increase β-cell mass need to be developed. To characterize mechanisms of β-cell plasticity, we studied a model of severe insulin resistance in the adult mouse and defined how β-cells adapt. Chronic corticosterone (CORT) treatment was given to adult mice and led to rapid insulin resistance and adaptive increased insulin secretion. Adaptive and massive increase of β-cell mass was observed during treatment up to 8 weeks. β-Cell mass increase was partially reversible upon treatment cessation and reinduced upon subsequent treatment. β-Cell neogenesis was suggested by an increased number of islets, mainly close to ducts, and increased Sox9 and Ngn3 mRNA levels in islets, but lineage-tracing experiments revealed that neoformed β-cells did not derive from Sox9- or Ngn3-expressing cells. CORT treatment after β-cell depletion partially restored β-cells. Finally, β-cell neogenesis was shown to be indirectly stimulated by CORT because serum from CORT-treated mice increased β-cell differentiation in in vitro cultures of pancreatic buds. Altogether, the results present a novel model of β-cell neogenesis in the adult mouse and identify the presence of neogenic factors in the serum of CORT-treated mice.

Early weight gain predicts later weight gain in depressed patients treated with antidepressants: Findings from the METADAP cohort

BACKGROUND

Weight gain is a major side effect of antidepressant (AD) drugs. We assessed whether early weight gain is a predictor for long term weight gain in depressed patients treated with antidepressants.

METHODS

In the six month prospective METADAP cohort, 260 non-overweight patients with a major depressive disorder (MDD), who have recently experienced a Major Depressive Episode (MDE) were assessed for early weight gain (>3%,>5%, and >7%) after one month of treatment, and for long term weight gain (>15% and >20%) after three and six months of treatment. ROC analysis was used to determine the predictive power of early weight gain.

RESULTS

12.4% (21/170) of patients became overweight after three months of treatment and 21.1% (26/123) were overweight after six months. Compared to non-early weight gainers, patients with early weight gain (>3%, >5% and >7%) were 11.3 (OR = 11.3, 95%CI: 4.6-27.6)], 9.9 (OR = 9.9, 95%CI: 3.6-26.9)] and 17.8 (OR = 17.8, 95%CI: 6.4-49.4)] times, respectively, more at risk of late weight gain (>15%). ROC analysis showed that early weight gain (>3%) after one month of treatment, was the best predictor of long term weight gain (≥15%) after three months [Area Under the Curve (AUC )= 87%] and six months of treatment (AUC = 88%) PERSPECTIVES: Given that our baseline sample consisted of strictly non-overweight patients, the 3% threshold for weight gain after one month should be used as an indicator to initiate early weight monitoring in depressed patients treated with antidepressants. High attrition rate remains a limitation in this cohort and other cohorts in psychiatric settings.

DISCLOSURES

Bruno Falissard consults for and received lecture fees from for E. Lilly, BMS, Servier, Sanofi-Aventis, GlaxoSmithKline, HRA, Roche, Boeringer Ingelheim, Bayer, Almirall, Allergan, Stallergene, Genzyme, Pierre Fabre, Astra Zeneca, Novartis, Janssen, Astellas, Biotronik, Daiichi-Sankyo, Gilead, MSD, Lundbeck. Florence Gressier received lecture fees from for Servier, Lundbeck and a grant from Servier. Mircea Polosan consults for and received lecture fees from Astra-Zeneca, Bristol Myers Squibb, Lundbeck, Otsuka and Servier. Emmanuel Haffen consults for and received lecture fees from Astra-Zeneca, Bristol Myers Squibb, Pfizer, Lilly, Lundbeck, Otsuka, Sanofi-Aventis, Servier. Philippe Chanson has received unrestricted research and educational grants from Ipsen, Novartis, Novo-Nordisk, and Pfizer for the Department of Endocrinology and Reproductive Diseases, Hôpitaux Universitaires Paris-Sud and for INSERM U 693. He has served as investigator (principal or coordinator) for clinical trials funded by Novartis, Pfizer, Ipsen, Italopharmaco, Antisense, Prolor Biotech. He is member of Advisory Boards from Ipsen, Novartis, Viropharma. He gave lectures for Ipsen, Novartis, Pfizer, NovoNordisk. All the fees and honoraria were paid to his Institution. Bruno Falissard consults for and received lecture fees from NovoNordisk, MSD and Sanofi-Aventis. Laurent Bequemont has close family member working at Sanofi-Aventis, consults for Sanofi-Aventis, Pfizer, Servier and received lecture fees from Genzyme, GlaxoSmithKline, Bristol-Myers Squibb and Merck Sharp and Dohme. Khalil El Asmar, Séverine Trabado, Albane Vievard, Céline Verstuyft, Romain Colle and Emmanuelle Corruble have nothing to declare.

MFN2-associated lipomatosis: Clinical spectrum and impact on adipose tissue

BACKGROUND

Multiple symmetric lipomatosis (MSL) is characterized by upper-body lipomatous masses frequently associated with metabolic and neurological signs. MFN2 pathogenic variants were recently implicated in a very rare autosomal recessive form of MSL. MFN2 encodes mitofusin-2, a mitochondrial fusion protein previously involved in Charcot-Marie-Tooth neuropathy.

OBJECTIVE

To investigate the clinical, metabolic, tissular, and molecular characteristics of MFN2-associated MSL.

METHODS

We sequenced MFN2 in 66 patients referred for altered fat distribution with one or several lipomas or lipoma-like regions and performed clinical and metabolic investigations in patients with positive genetic testing. Lipomatous tissues were studied in 3 patients.

RESULTS

Six patients from 5 families carried a homozygous p.Arg707Trp pathogenic variant, representing the largest reported series of MFN2-associated MSL. Patients presented both lipomatous masses and a lipodystrophic syndrome (lipoatrophy, low leptinemia and adiponectinemia, hypertriglyceridemia, insulin resistance and/or diabetes). Charcot-Marie-Tooth neuropathy was of highly variable clinical severity. Lipomatous tissue mainly contained hyperplastic unilocular adipocytes, with few multilocular cells. It displayed numerous mitochondrial alterations (increased number and size, structural defects). As compared to control subcutaneous fat, mRNA and protein expression of leptin and adiponectin was strikingly decreased, whereas the CITED1 and fibroblast growth factor 21 (FGF21) thermogenic markers were strongly overexpressed. Consistently, serum FGF21 was markedly increased, and ¹⁸F-FDG-PET-scan revealed increased fat metabolic activity.

CONCLUSION

MFN2-related MSL is a novel mitochondrial lipodystrophic syndrome involving both lipomatous masses and lipoatrophy. Its complex neurological and metabolic phenotype justifies careful clinical evaluation and multidisciplinary care. Low leptinemia and adiponectinemia, high serum FGF21, and increased ¹⁸F-FDG body fat uptake may be disease markers.

Plasma BDNF Level in Major Depression: Biomarker of the Val66Met BDNF Polymorphism and of the Clinical Course in Met Carrier Patients

AIMS

Despite the involvement of the brain-derived neurotrophic factor (BDNF) in the physiopathology of major depressive disorder (MDD), the coherence between the components of the BDNF pathway and their link with the clinical features of MDD are insufficiently studied. We aimed to assess in Caucasian depressed patients the impact of the BDNF Val66Met polymorphism on plasma BDNF levels taking into account the clinical characteristics of MDD.

METHODS

A total of 328 Caucasian adult MDD patients with a current major depressive episode (MDE) were assessed for the BDNF Val66Met polymorphism, plasma BDNF levels and clinical characteristics of the MDD.

RESULTS

Plasma BDNF levels were linearly associated with the BDNF Val66Met genotypes (ValVal: 1,525.9 ± 1,183.3 pg/mL vs. ValMet: 1,248.7 ± 1,081.8 vs. MetMet: 1,004.9 ± 952.8; p = 0.04), Met carriers having lower BDNF levels than ValVal ones. Significant interactions between the Val66Met polymorphism and 3 clinical characteristics - age at onset (p = 0.03), MDD duration (p = 0.04), and number of previous MDE (p = 0.04) - were evidenced for plasma BDNF levels. Indeed, in Met carriers, but not in ValVal ones, plasma BDNF levels were negatively correlated with age at onset and positively correlated with MDD duration and number of previous MDE.

CONCLUSION

Our results show a measurable, coherent, and functional BDNF pathway based on the BDNF Val66Met polymorphism and plasma BDNF levels in patients with a current MDE. This pathway is related to the clinical course of major depression, plasma BDNF levels being associated with the long-term history of MDD in Met carriers. Further studies assessing central BDNF are needed to understand the underlying mechanisms of this association.

The association of β-arrestin2 polymorphisms with response to antidepressant treatment in depressed patients

The study of genetic polymorphisms involved in antidepressants (AD) response is essential to provide a personalized medicine approach in the field of depression. β-arrestin 2 (ARRB2) is a candidate gene in the pharmacogenetics of AD as it is involved in the signaling cascade downstream of numerous neurotransmitter receptors. We investigated the association between five ARRB2 single nucleotide polymorphisms (SNPs): rs1045280, rs2036657, rs4790694, rs3786047 and rs452246, and response to AD treatment in a sample of 569 patients with a major depressive episode treated for 6months. We show that GG/GT patients for rs4522461 (n=534) and AA/AC patients for rs4790694 (n=244) have a lower response to AD than other genotype groups (HDRS score of 10.9 vs 8.0 after 6months, multivariate analysis: p=0.03; 12.2 vs 9.6, p=0.02, respectively). These data provide additional evidence that β-arrestin 2 is a regulator of intracellular signal transduction processes involved in AD treatment.

Implication of Free Fatty Acids in Thrombin Generation and Fibrinolysis in Vascular Inflammation in Zucker Rats and Evolution with Aging

Background: The metabolic syndrome (MetS) and aging are associated with modifications in blood coagulation factors, vascular inflammation, and increased risk of thrombosis. Objectives: Our aim was to determine concomitant changes in thrombin generation in the blood compartment and at the surface of vascular smooth muscle cells (VSMCs) and its interplay with adipokines, free fatty acids (FFA), and metalloproteinases (MMPs) in obese Zucker rats that share features of the human MetS. Methods: Obese and age-matched lean Zucker rats were compared at 25 and 80 weeks of age. Thrombin generation was assessed by calibrated automated thrombography (CAT). Results: Endogenous thrombin potential (ETP) was increased in obese rats independent of platelets and age. Clot half-lysis time was delayed with obesity and age. Interleukin (IL)-1β and IL-13 were increased with obesity and age respectively. Addition of exogenous fibrinogen, leptin, linoleic, or palmitic acid increased thrombin generation in plasma whereas adiponectin had an opposite effect. ETP was increased at the surface of VSMCs from obese rats and addition of exogenous palmitic acid further enhanced ETP values. Gelatinase activity was increased in aorta at both ages in obese rats and MMP-2 activity was increased in VSMCs from obese rats. Conclusions: Our study demonstrated in MetS an early prothrombotic phenotype of the blood compartment reinforced by procoagulant properties of dedifferentiated and inflammatory VSMCs. Mechanisms involved (1) increased fibrinogen and impaired fibrinolysis and (2) increased saturated fatty acids responsible for additive procoagulant effects. Whether specifically targeting this hypercoagulability using direct thrombin inhibitors would improve outcome in MetS is worth investigating.

Antenatal antipsychotic exposure induces multigenerational and gender-specific programming of adiposity and glucose tolerance in adult mouse offspring

Second-generation antipsychotics (SGAs) are well known for their metabolic side effects in humans, including obesity and diabetes. These compounds are maintained during pregnancy to prevent the relapse of psychoses, but they readily diffuse across the placenta to the fetus, as documented with the widely-prescribed drug olanzapine (OLZ). However, observational studies have provided conflicting results on the potential impact of SGAs on fetal growth and body weight, and their effects on metabolic regulation in the offspring. For this reason, our study has tested whether antenatal exposure of CD1 mice to OLZ influenced metabolic outcomes in the offspring of the first (F1) and second (F2) generations. In F1 mice, OLZ antenatal treatment caused a decrease in neonatal body weight in both genders, an effect that persisted throughout life only in male animals. Interestingly, F1 female mice also displayed altered glucose homoeostasis. F2 mice, generated by mating normal males with F1 female mice exposed to OLZ during antenatal life, exhibited higher neonatal body weights which persisted only in F2 female animals. This was associated with expansion of fat mass and a concordant pattern of adipose tissue gene expression. Moreover, male and female F2 mice were glucose-intolerant. Thus, our study has demonstrated that antenatal OLZ exposure induces multigenerational and gender-specific programming of glucose tolerance in the offspring mice as adults, and points to the need for careful monitoring of children exposed to SGAs during pregnancy.