Early macrophage response to obesity encompasses Interferon Regulatory Factor 5 regulated mitochondrial architecture remodelling.

Adipose tissue macrophages (ATM) adapt to changes in their energetic microenvironment. Caloric excess, in a range from transient to diet-induced obesity, could result in the transition of ATMs from highly oxidative and protective to highly inflammatory and metabolically deleterious. Here, we demonstrate that Interferon Regulatory Factor 5 (IRF5) is a key regulator of macrophage oxidative capacity in response to caloric excess. ATMs from mice with genetic-deficiency of Irf5 are characterised by increased oxidative respiration and mitochondrial membrane potential. Transient inhibition of IRF5 activity leads to a similar respiratory phenotype as genomic deletion, and is reversible by reconstitution of IRF5 expression. We find that the highly oxidative nature of Irf5-deficient macrophages results from transcriptional de-repression of the mitochondrial matrix component Growth Hormone Inducible Transmembrane Protein (GHITM) gene. The Irf5-deficiency-associated high oxygen consumption could be alleviated by experimental suppression of Ghitm expression. ATMs and monocytes from patients with obesity or with type-2 diabetes retain the reciprocal regulatory relationship between Irf5 and Ghitm. Thus, our study provides insights into the mechanism of how the inflammatory transcription factor IRF5 controls physiological adaptation to diet-induced obesity via regulating mitochondrial architecture in macrophages.

Towards individualised and optimalised positioning of non-ventilated COVID-19 patients: Putting the affected parts of the lung(s) on top?

The outbreak of COVID-19 led to an unprecedented inflow of hospitalised patients with severe acute respiratory syndrome (SARS), requiring high-flow non-invasive oxygenation, if not invasive mechanical ventilation. While the best option in terms of non-invasive systems of oxygen delivery is still a matter of debate, it also remains unclear as to whether or not the optimal in-bed positioning of patients might also help to improve their oxygen saturation levels. On the basis of three representative cases, it is possible to propose the following hypotheses: (i) how patients are positioned has a strong influence on their oxygen saturation levels; (ii) saturation-optimalised positions are patient-specific; (iii) prone positions require ergonomic devices; and (iv) saturation-optimalised positions should aim to place the most affected part(s) of the lung(s) on top. Considered together, these hypotheses have led us to recommend that COVID-19 patients should undergo a specific assessment at admission to determine their saturation-optimalised in-bed position. However, further studies are still needed to assess the benefits of such a strategy on clinical outcomes.

Acquired generalized lipodystrophy under immune checkpoint inhibition.

Immune checkpoint inhibitors are now the standard of care in the treatment of several types of cancer. Cutaneous immune-related adverse events (irAEs) are usually of low grade and reversible, while endocrine irAEs are generally irreversible and managed with hormone replacement therapy. We report a 47-year-old patient, treated with the anti-programmed cell death (PD)1 antibody pembrolizumab for a metastatic melanoma, who developed severe lipodystrophy after 10 months of treatment, characterized by the loss of subcutaneous fat tissue, central obesity and insulin resistance with a decreased leptin level. Histological analysis of a cutaneous biopsy revealed subcutaneous fat cell destruction associated with oedema, the presence of lipophages, and a CD3+ lymphocytic infiltrate involving the panniculus. This led to the diagnosis of anti-PD-1-induced acquired generalized lipodystrophy, after ruling out differential diagnoses (i.e. genetic and systemic autoimmune diseases). No corticosteroids were introduced considering the high risk of inducing severe metabolic complications, and pembrolizumab was discontinued as complete response of the melanoma was achieved. However, after 12 months of follow-up, lipodystrophy and its severe metabolic complications are still ongoing. What's already known about this topic? Anti-programmed cell death (PD)1 agents are now a standard of care in the treatment of several cancers, including melanoma. Endocrine and cutaneous immune-related adverse events (irAEs) are among the most frequent irAEs (14-30% and 30-40%, respectively) in patients treated with immune checkpoint inhibitors. What does this study add? Acquired generalized lipodystrophy can occur during anti-PD1 therapy and is associated with severe metabolic complications. With the increase in anti-PD1 prescription in several cancer types, clinicians must be aware of the whole range of irAEs that may occur.

Determinants of aspirin resistance in patients with type 2 diabetes.

BACKGROUND: Cardiovascular disease is a leading cause of mortality among patients with type 2 diabetes mellitus (T2DM). Numerous patients with T2DM show resistance to aspirin treatment, which may explain the higher rate of major adverse cardiovascular events observed compared with non-diabetes patients, and it has recently been shown that aspirin resistance is mainly related to accelerated platelet turnover with persistent high platelet reactivity (HPR) 24h after last aspirin intake. The mechanism behind HPR is unknown. The aim of this study was to investigate the precise rate and mechanisms associated with HPR in a population of T2DM patients treated with aspirin. METHODS: Included were 116 consecutive stable T2DM patients who had attended our hospital for their yearly check-up. HPR was assessed 24h after aspirin intake using light transmission aggregometry (LTA) with arachidonic acid (AA) and serum thromboxane B2 (TXB2) measurement. Its relationship with diabetes status, insulin resistance, inflammatory markers and coronary artery disease (CAD) severity, using calcium scores, were investigated. RESULTS: Using LTA, HPR was found in 27 (23%) patients. There was no significant difference in mean age, gender ratio or cardiovascular risk factors in patients with or without HPR. HPR was significantly related to duration of diabetes and higher fasting glucose levels (but not consistently with HbA1c), and strongly related to all markers of insulin resistance, especially waist circumference, HOMA-IR, QUICKI and leptin. There was no association between HPR and thrombopoietin or inflammatory markers (IL-6, IL-10, indoleamine 2,3-dioxygenase activity, TNF-α, C-reactive protein), whereas HPR was associated with more severe CAD. Similar results were found with TXB2. CONCLUSION: Our results reveal that 'aspirin resistance' is frequently found in T2DM, and is strongly related to insulin resistance and severity of CAD, but weakly related to HbA1c and not at all to inflammatory parameters. This may help to identify those T2DM patients who might benefit from alternative antiplatelet treatments such as twice-daily aspirin and thienopyridines.

Oxidative and energetic stresses mediate beta-cell dysfunction induced by PGC-1α.

AIM: Alteration of functional beta-cell mass in adults can be programmed by adverse events during fetal life. Previously, it was demonstrated that high glucocorticoid (GC) levels during fetal life participate in this programming by inhibition of beta-cell development. More specifically, GC levels stimulate expression of peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α), a transcriptional co-regulator of the GC receptor (GR), which per se impairs beta-cell mass and function when overexpressed. As PGC-1α is also a potent inducer of mitochondrial biogenesis, our study aimed to determine how PGC-1α modifies mitochondrial function in beta cells and how it might regulate insulin secretion. METHODS: Beta-cell function was studied in mice overexpressing PGC-1α specifically in beta cells and in MIN6 cells overexpressing PGC-1α in vitro. RESULTS: PGC-1α overexpression in beta cells in vivo leads to a reduced beta-cell mass early in fetal life, whereas PGC-1α overexpression in vitro stimulates mitochondrial biogenesis and respiratory activity without improving ATP production, while increasing oxidative stress and impairing insulin secretion in response to glucose. While oxidative stress with PGC-1α overexpression in beta cells activates AMPK, it has also been revealed that blocking such oxidative stress or AMPK activation restores insulin secretion. CONCLUSION: PGC-1α induces oxidative stress, which disrupts insulin secretion by AMPK activation. Thus, control of oxidative or energetic stress in beta cells may help to restore insulin secretion.

Relationship between HHV8 infection markers and insulin sensitivity in ketosis-prone diabetes.

BACKGROUND AND OBJECTIVES: Peripheral tissue resistance to insulin action is a characteristic of type 2 diabetes mellitus (T2DM). It has also been reported that some chronic viral infections can contribute to insulin resistance. Human herpesvirus (HHV)-8 infection has been detected in T2DM patients in previous studies. Our study investigated whether the presence of the virus is associated with insulin resistance in patients with ketosis-prone type 2 diabetes (KPD), as reported with other viruses. RESEARCH DESIGN AND METHODS: A total of 11 insulin-free KPD patients positive (+) and seven patients who were negative (-) for HHV-8 infection were recruited; the latter had KPD that was well controlled (HbA1c=6.2±0.7%). A two-step euglycaemic-hyperinsulinaemic clamp test coupled with deuterated [6,6-2H2]glucose was used to assess insulin sensitivity, non-esterified fatty acid (NEFA) suppression and endogenous glucose production. RESULTS: In KPD patients, whether HHV-8+ or HHV-8-, there were no differences in NEFA release, endogenous glucose production or insulin sensitivity (M value). CONCLUSION: Asymptomatic HHV-8 infection does not appear to be associated with decreased insulin sensitivity in diabetic patients. These results should now be confirmed in a larger sample population.

Ketosis-prone atypical diabetes in Cameroonian people with hyperglycaemic crisis: frequency, clinical and metabolic phenotypes.

AIM: It is unclear whether ketosis-prone diabetes is a specific type or a subtype of Type 2 diabetes. We aimed to describe the clinical and metabolic features of ketosis-prone diabetes in a sub-Saharan population. METHODS: We consecutively enrolled and characterized 173 people with non-autoimmune diabetes admitted for hyperglycaemic crisis at the Yaoundé Central Hospital, Cameroon. Blood samples were collected for fasting glucose, HbA1c , lipid profile and C-peptide assays with insulin resistance and secretion estimation by homeostasis model assessment. People were classified as having Type 2 diabetes (n = 124) or ketosis-prone diabetes (n = 49). Ketosis-prone diabetes was sub-classified as new-onset ketotic phase (n = 34) or non-ketotic phase (n = 15). RESULTS: Ketosis-prone diabetes was found in 28.3% of the hyperglycaemic crises. Age at diabetes diagnosis was comparable in Type 2 and ketosis-prone diabetes [48 ± 14 vs 47 ± 11 years; P = 0.13] with a similar sex distribution. Overall BMI was 27.7 ± 13.4 kg/m2 and was ≥ 25 kg/m2 in 55.8% of those taking part, however, 73.5% of those with ketosis-prone diabetes reported weight loss of > 5% at diagnosis. Blood pressure and lipid profile were comparable in both types. Ketosis-prone diabetes in the ketotic phase was characterized by lower insulin secretion and higher serum triglycerides compared with non-ketotic ketosis prone and Type 2 diabetes. Type 2 and ketosis prone diabetes in the non-ketotic phase were comparable in terms of lipid profile, blood pressure, waist-to-hip ratio, BMI and fat mass, insulin secretion and insulin resistance indices. CONCLUSIONS: Ketosis-prone diabetes is likely to be a subtype of Type 2 diabetes with the potential to develop acute insulinopenic episodes.

Which oral antidiabetic drug to combine with metformin to minimize the risk of hypoglycemia when initiating basal insulin?: A randomized controlled trial of a DPP4 inhibitor versus insulin secretagogues.

We conducted a pilot study to evaluate two therapeutic strategies at the time of insulin initiation in type 2 diabetic patients insufficiently controlled with metformin+insulin-secretagogues (IS, sulfonylureas or glinides). Patients were randomized to remain under the same dual therapy or to receive metformin+DPP4 inhibitors while starting insulin. Similar glycemic control was achieved in both groups. However less hypoglycemia was observed with DPP4 inhibitors despite higher doses of insulin.

Hyperglycaemia per se does not affect erythrocyte glucose-6-phosphate dehydrogenase activity in ketosis-prone diabetes.

AIM: Previously, we described patients with ketosis-prone type 2 diabetes (KPD) and glucose-6-phosphate dehydrogenase (G6PD) deficiency, but no mutation of the G6PD gene. Our present study used two complementary approaches to test whether hyperglycaemia might inhibit G6PD activity: (1) effect of acute hyperglycaemia induced by glucose ramping; and (2) effect of chronic hyperglycaemia using correlation between G6PD activity and HbA1c levels. METHODS: In the first substudy, 16 KPD patients were compared with 11 healthy, non-diabetic control subjects of the same geographical background. Erythrocyte G6PD activity and plasma glucose were assessed at baseline and every 40 min during intravenous glucose ramping that allowed maintaining hyperglycaemia for more than 3h. In the second substudy, erythrocyte G6PD activity and HbA1c levels were evaluated in 108 consecutive African patients with either type 2 diabetes or KPD, and a potential correlation sought between the two variables. RESULTS: The maximum plasma glucose level after 200 min of glucose perfusion was 20.9±3.7 mmol/L for patients and 10.7±2.3mmol/L for controls. There was no difference between baseline and repeated G6PD activity levels during acute hyperglycaemia in either KPD patients (P=0.94) or controls (P=0.57), nor was there any significant correlation between residual erythrocyte G6PD activity and HbA1c levels (r=-0.085, P=0.38). CONCLUSION: Neither acute nor chronic hyperglycaemia affects erythrocyte G6PD activity. Thus, hyperglycaemia alone does not explain cases of G6PD deficiency in the absence of gene mutation as described earlier.

Metabolic roles of PGC-1α and its implications for type 2 diabetes.

PGC-1α is a transcriptional coactivator expressed in brown adipose tissue, liver, pancreas, kidney, skeletal and cardiac muscles, and the brain. This review presents data illustrating how PGC-1α regulates metabolic adaptations and participates in the aetiology of type 2 diabetes (T2D). Studies in mice have shown that increased PGC-1α expression may be beneficial or deleterious, depending on the tissue: in adipose tissue, it promotes thermogenesis and thus protects against energy overload, such as seen in diabetes and obesity; in muscle, PGC-1α induces a change of phenotype towards oxidative metabolism. In contrast, its role is clearly deleterious in the liver and pancreas, where it induces hepatic glucose production and inhibits insulin secretion, changes that promote diabetes. Previous studies by our group have also demonstrated the role of PGC-1α in the fetal origins of T2D. Overexpression of PGC-1α in ß cells during fetal life in mice is sufficient to induce ß-cell dysfunction in adults, leading to glucose intolerance. PGC-1α also is associated with glucocorticoid receptors in repressing expression of Pdx1, a key ß-cell transcription factor. In conclusion, PGC-1α participates in the onset of diabetes through regulation of major metabolic tissues. Yet, it may not represent a useful target for therapeutic strategies against diabetes as it exerts both beneficial and deleterious actions on glucose homoeostasis, and because PGC-1α modulation is involved in neurodegenerative diseases. However, its role in cellular adaptation shows that greater comprehension of PGC-1α actions is needed.

Incretin-based therapy and pancreatic beta cells.

Type 2 diabetes (T2D) is a complex, progressive disease with life-threatening complications and one of the most serious public-health problems worldwide. The two main mechanisms of T2D pathogenesis are pancreatic beta cell dysfunction and insulin resistance. It is now recognized that pancreatic beta cell dysfunction is a necessary factor for T2D development. Traditional therapies for controlling blood glucose are suboptimal as they fail to meet target goals for many patients. Glucagon-like peptide-1 receptor agonists (GLP1RA) and dipeptidyl peptidase-4 inhibitors (DPP4I) are an attractive class of therapy because they reduce blood glucose by targeting the incretin hormone system and, in particular, have the potential to positively affect pancreatic beta cell biology. This review outlines our current understanding of pancreatic beta cell incretin system dysfunction in T2D and summarizes recent evidence of the effect of incretin-based therapies on beta cell function and mass. Incretin-based therapies have shown strong evidence for beneficial effects on beta cell function and mass in animal studies. In humans, incretin-based therapies are effective glucose-lowering agents, but further study is still required to evaluate their long-term effects on beta cell function and safety as well as beta cell mass expansion.

Pronounced reduction of postprandial glucagon by lixisenatide: a meta-analysis of randomized clinical trials.

AIM: Glucagon-like peptide-1 (GLP-1) receptor agonists improve islet function and delay gastric emptying in patients with type 2 diabetes mellitus (T2DM). This meta-analysis aimed to investigate the effects of the once-daily prandial GLP-1 receptor agonist lixisenatide on postprandial plasma glucose (PPG), glucagon and insulin levels. METHODS: Six randomized, placebo-controlled studies of lixisenatide 20 µg once daily were included in this analysis: lixisenatide as monotherapy (GetGoal-Mono), as add-on to oral antidiabetic drugs (OADs; GetGoal-M, GetGoal-S) or in combination with basal insulin (GetGoal-L, GetGoal-Duo-1 and GetGoal-L-Asia). Change in 2-h PPG and glucose excursion were evaluated across six studies. Change in 2-h glucagon and postprandial insulin were evaluated across two studies. A meta-analysis was performed on least square (LS) mean estimates obtained from analysis of covariance (ANCOVA)-based linear regression. RESULTS: Lixisenatide significantly reduced 2-h PPG from baseline (LS mean difference vs. placebo: -4.9 mmol/l, p < 0.001) and glucose excursion (LS mean difference vs. placebo: -4.5 mmol/l, p < 0.001). As measured in two studies, lixisenatide also reduced postprandial glucagon (LS mean difference vs. placebo: -19.0 ng/l, p < 0.001) and insulin (LS mean difference vs. placebo: -64.8 pmol/l, p < 0.001). There was a stronger correlation between 2-h postprandial glucagon and 2-h PPG with lixisenatide than with placebo. CONCLUSIONS: Lixisenatide significantly reduced 2-h PPG and glucose excursion together with a marked reduction in postprandial glucagon and insulin; thus, lixisenatide appears to have biological effects on blood glucose that are independent of increased insulin secretion. These effects may be, in part, attributed to reduced glucagon secretion.

Influence of migration on characteristics of type 2 diabetes in sub-Saharan Africans.

AIM: This study compared the clinical and biochemical characteristics and microvascular complications found in three groups of type 2 diabetes (T2D) patients: Africans living in Africa; African immigrants living in France; and Caucasians living in France. METHODS: Diagnosed T2D Africans living in Cameroon (n=100) were compared with 98 African migrants diagnosed with T2D after having moved to France, and a group of 199 T2D Caucasian patients living in France. All underwent clinical and biochemical evaluations, and all were assessed for microvascular complications. RESULTS: The median duration of stay of the migrants in France was 15years before being diagnosed with diabetes. Despite similar durations of diagnosis, they were 8.9years younger at the time of diagnosis than Africans living in Cameroon (P<0.001). Caucasians and African immigrants in France had lower HbA1c values than Africans in Cameroon (P<0.001); they were also more aggressively treated for hypertension and dyslipidaemia and, therefore, had significantly lower blood pressure levels and better lipid profiles. Diabetic nephropathy and retinopathy rates were higher in Cameroon than in the two other groups. After adjusting for age, diabetes duration, HbA1c, hypertension and other covariates, only the prevalence of diabetic nephropathy (OR: 5.61, 95% CI: 2.32-13.53; P<0.0001) was higher in Cameroon compared with those living in France. CONCLUSION: Our results suggest that Africans who emigrate to France may develop diabetes earlier than those staying in their home country. However, the latter may be a reflection of late diagnosis of diabetes. Also, the less adequate diabetes and hypertension control in the latter would explain their higher rates of nephropathy. Large-scale cohorts are now warranted to substantiate these observations.

Physical activity and type 2 diabetes. Recommandations of the SFD (Francophone Diabetes Society) diabetes and physical activity working group.

Although regular physical activity is an integral part of T2D management, few diabetic patients have a sufficient level of physical activity. However over the past decade or so, the beneficial effects of regular physical activity have been well demonstrated, both in T2D prevention (50% reduction in the incidence of T2D in subjects with high metabolic risk) as well as T2D management for the improvement of glycaemic control (mean 0.7% improvement of HbA1c) and the reduction of T2D-related comorbidities (improvement in blood pressure values and lipid profile, decrease in insulin resistance). Physical activity has both acute effects (effects of one exercise session) and more prolonged effects of exercise when it is repeated on a regular basis (training effect). In addition, the physical activity recommendations have been extended to a wide range of physical activities (by combining both endurance and muscle strengthening exercises), thus varying the physical activity practiced according to the patient's available time, practice sites, preferences and interests. Following a pathophysiology review, the effects of physical activity will be discussed and presented in terms of evidence-based medicine. The recommendations will be defined and practical prescribing information will be suggested, while taking into account that clinicians are concerned with answering questions regarding how, where and with whom: how can patients be motivated to practice a physical activity over the long-term? And how can qualified exercise trainers and appropriate practice settings be found?

Zinc transporter (ZnT)8(186-194) is an immunodominant CD8+ T cell epitope in HLA-A2+ type 1 diabetic patients.

AIMS/HYPOTHESIS: Anti-zinc transporter (ZnT)8 autoantibodies are commonly detected in type 1 diabetic patients. We hypothesised that ZnT8 is also recognised by CD8(+) T cells and aimed to identify HLA-A2 (A*02:01)-restricted epitope targets. METHODS: Candidate epitopes were selected by ZnT8 plasmid DNA immunisation of HLA-A2/DQ8 transgenic mice and tested for T cell recognition in peripheral blood mononuclear cells of type 1 diabetic, type 2 diabetic and healthy participants by IFN-γ enzyme-linked immunospot. RESULTS: White HLA-A2(+) adults (83%) and children (60%) with type 1 diabetes displayed ZnT8-reactive CD8(+) T cells that recognised a single ZnT8(186-194) (VAANIVLTV) epitope. This ZnT8(186-194)-reactive fraction accounted for 50% to 53% of total ZnT8-specific CD8(+) T cells. Another sequence, ZnT8(153-161) (VVTGVLVYL), was recognised in 20% and 25% of type 1 diabetic adults and children, respectively. Both epitopes were type 1 diabetes-specific, being marginally recognised by type 2 diabetic and healthy participants (7-12% for ZnT8(186-194), 0% for ZnT8(153-161)). CONCLUSIONS/INTERPRETATION: ZnT8-reactive CD8(+) T cells are predominantly directed against the ZnT8(186-194) epitope and are detected in a majority of type 1 diabetic patients. The exceptional immunodominance of ZnT8(186-194) may point to common environmental triggers precipitating beta cell autoimmunity.