Islets in the body are never flat: transitioning from two-dimensional (2D) monolayer culture to three-dimensional (3D) spheroid for better efficiency in the generation of functional hPSC-derived pancreatic ß cells in vitro.

Diabetes mellitus (DM), currently affecting more than 537 million people worldwide is a chronic disease characterized by impaired glucose metabolism resulting from a defect in insulin secretion, action, or both due to the loss or dysfunction of pancreatic ß cells. Since cadaveric islet transplantation using Edmonton protocol has served as an effective intervention to restore normoglycaemia in T1D patients for months, stem cell-derived ß cells have been explored for cell replacement therapy for diabetes. Thus, great effort has been concentrated by scientists on developing in vitro differentiation protocols to realize the therapeutic potential of hPSC-derived ß cells. However, most of the 2D traditional monolayer culture could mainly generate insulin-producing ß cells with immature phenotype. In the body, pancreatic islets are 3D cell arrangements with complex cell-cell and cell-ECM interactions. Therefore, it is important to consider the spatial organization of the cell in the culture environment. More recently, 3D cell culture platforms have emerged as powerful tools with huge translational potential, particularly for stem cell research. 3D protocols provide a better model to recapitulate not only the in vivo morphology, but also the cell connectivity, polarity, and gene expression mimicking more physiologically the in vivo cell niche. Therefore, the 3D culture constitutes a more relevant model that may help to fill the gap between in vitro and in vivo models. Interestingly, most of the 2D planar methodologies that successfully generated functional hPSC-derived ß cells have switched to a 3D arrangement of cells from pancreatic progenitor stage either as suspension clusters or as aggregates, suggesting the effect of 3D on ß cell functionality. In this review we highlight the role of dimensionality (2D vs 3D) on the differentiation efficiency for generation of hPSC-derived insulin-producing ß cells in vitro. Consequently, how transitioning from 2D monolayer culture to 3D spheroid would provide a better model for an efficient generation of fully functional hPSC-derived ß cells mimicking in vivo islet niche for diabetes therapy or drug screening. Video Abstract.

ß-cell mitochondria in diabetes mellitus: a missing puzzle piece in the generation of hPSC-derived pancreatic ß-cells?

Diabetes mellitus (DM), currently affecting 463 million people worldwide is a chronic disease characterized by impaired glucose metabolism resulting from the loss or dysfunction of pancreatic ß-cells with the former preponderating in type 1 diabetes (T1DM) and the latter in type 2 diabetes (T2DM). Because impaired insulin secretion due to dysfunction or loss of pancreatic ß-cells underlies different types of diabetes, research has focused its effort towards the generation of pancreatic ß-cells from human pluripotent stem cell (hPSC) as a potential source of cells to compensate for insulin deficiency. However, many protocols developed to differentiate hPSCs into insulin-expressing ß-cells in vitro have generated hPSC-derived ß-cells with either immature phenotype such as impaired glucose-stimulated insulin secretion (GSIS) or a weaker response to GSIS than cadaveric islets. In pancreatic ß-cells, mitochondria play a central role in coupling glucose metabolism to insulin exocytosis, thereby ensuring refined control of GSIS. Defects in ß-cell mitochondrial metabolism and function impair this metabolic coupling. In the present review, we highlight the role of mitochondria in metabolism secretion coupling in the ß-cells and summarize the evidence accumulated for the implication of mitochondria in ß-cell dysfunction in DM and consequently, how targeting mitochondria function might be a new and interesting strategy to further perfect the differentiation protocol for generation of mature and functional hPSC-derived ß-cells with GSIS profile similar to human cadaveric islets for drug screening or potentially for cell therapy.

High rate of virological failure and HIV drug resistance in semi-rural Gabon and implications for dolutegravir-based regimen efficacy.

BACKGROUND: The projected UNAIDS goal of ending AIDS by 2030 requires significant global efforts to improve current and future ART strategies. In this study, we assessed viral load (VL) suppression and acquired drug resistance, as well as future efficacy of dolutegravir-based combinations for patients living in semi-rural regions of Gabon. METHODS: Eligible study participants were adults receiving ART and recruited between 2018 and 2019 in Franceville, Gabon. VL testing was conducted to assess VL suppression and HIV drug resistance (HIVDR) testing was performed to identify resistance mutations and assess their impact on ongoing and future ART regimens. RESULTS: We recruited 219 participants overall. The median time on ART was 27 months and 216/219 participants were on first-line ART. VL suppression (VL < 1000 copies/mL) was 57.1% (95% CI 50.5-63.8) overall; 59.4% (51.4-67.5) and 52.2% (40.3-64.2) for women and men, respectively. The overall prevalence of HIVDR was 21.9% among the study population and 67.2% among those who failed ART. Presence of both NRTI and NNRTI mutations was found in 84.6% of sequences with drug resistance mutations, and full activity of a dolutegravir-based first-line regimen including tenofovir disoproxil fumarate/lamivudine/dolutegravir was expected only for 5/39 patients with a resistant virus. CONCLUSIONS: This study shows a very low rate of VL suppression in a semi-rural context in Africa. Moreover, the high burden of HIVDR has affected both current and newly recommended ART strategies. Better management of ART in resource-limited settings is still a challenging ambition.

Low birth weight causes insulin resistance and aberrant intestinal lipid metabolism independent of microbiota abundance in Landrace-Large White pigs.

Low birth weight (LBW) and postnatal nutrition are risk factors for adult metabolic diseases. However, the interactions between LBW, diet, and intestinal lipid absorption and secretion leading to adult metabolic disease remain unclear. The current study determined the impact of LBW on intestinal lipid and carbohydrate metabolism under both control and Western diet (high fat, high fructose, and cholesterol) conditions in 5-wk-old LBW and normal birth weight (NBW) Landrace-Large White × Duroc pigs. A 2-step modified oral glucose and fat challenge test was performed. Mesenteric lymph, jejunal mucosal scrapings, and cecal digesta samples were also collected. LBW offspring were lower in weight and gained less weight per day. LBW pigs on either control or Western diets displayed increased triglyceride (TG) secretion into lymph (P = 0.0135). Western diet-fed LBW pigs developed fasting (P = 0.03) and postprandial (P < 0.05) hypertriglyceridemia, muscle steatosis (P = 0.0072), had higher insulin excursion (P < 0.01), increased jejunal stearoyl-CoA desaturase 1 mRNA and increased hepatic fibrosis (P = 0.0017) compared with NBW piglets. Gut microbiota showed significant dysbiosis on Western diet independent of birth weight. In conclusion, LBW pigs fed a Western diet specifically up-regulate TG absorption and secretion, develop dyslipidemia, muscular steatosis, and display early signs of insulin resistance. Interestingly, this study does not provide evidence of altered intestinal microbiome in LBW pigs contributing to increased severity of metabolic diseases.-Fontaine, M. A., Diane, A., Singh, V. P., Mangat, R., Krysa, J. A., Nelson, R., Willing, B. P., Proctor, S. D. Low birth weight causes insulin resistance and aberrant intestinal lipid metabolism independent of microbiota abundance in Landrace-Large White pigs.

High prevalence of human T-cell leukemia virus type-1b genotype among blood donors in Gabon, Central Africa.

BACKGROUND: The African continent is considered to be the largest endemic area of HTLV-1 infection, with at least several million infected individuals. Systematic screening of blood donors can prevent the transmission of HTLV-1 in blood. Gabon is one of the countries with the highest prevalence of HTLV-1 worldwide, and yet the routine testing of blood donors has still not been introduced. METHODS: All blood donations collected between April and July 2017 at the Centre National de Transfusion Sanguine of Gabon were studied. Plasma samples were screened by ELISA for the presence of HTLV-1/2 antibodies. Western blot (WB) and polymerase chain reaction (PCR) tests were used for confirmation. RESULTS: In total, 3123 blood donors were tested, including 1740 repeat and 1378 first-time blood donors (FTBDs). Of them, 132 samples tested positive for HTLV-1/2 by ELISA (4.2%). WB and PCR confirmed HTLV-1 infection for 23 individuals. The overall prevalence of HTLV-1 was 0.74% [95% CI 0.47%-1.10%], 1% in FTBD, and 0.5% in repeat donors. Age and sex-adjusted prevalence was five-fold lower in FTBD than in the general adult population of rural areas of Gabon. All detected HTLV-1 strains belonged to the central African HTLV-1b genotype but were highly diverse. CONCLUSION: We report an overall prevalence of HTLV-1 of 0.74%, one of the highest values reported for blood donors in Africa. Given the high risk of HTLV-1 transmission in blood, it is necessary to conduct cost-effectiveness studies to determine the need and feasibility of implementing screening of HTLV-1 in blood donors in Gabon.

Vaccenic acid suppresses intestinal inflammation by increasing anandamide and related N-acylethanolamines in the JCR:LA-cp rat.

Vaccenic acid (VA), the predominant ruminant-derivedtransfat in the food chain, ameliorates hyperlipidemia, yet mechanisms remain elusive. We investigated whether VA could influence tissue endocannabinoids (ECs) by altering the availability of their biosynthetic precursor, arachidonic acid (AA), in membrane phospholipids (PLs). JCR:LA-cprats were assigned to a control diet with or without VA (1% w/w),cis-9,trans-11 conjugated linoleic acid (CLA) (1% w/w) or VA+CLA (1% + 0.5% w/w) for 8 weeks. VA reduced the EC, 2-arachidonoylglycerol (2-AG), in the liver and visceral adipose tissue (VAT) relative to control diet (P< 0.001), but did not change AA in tissue PLs. There was no additive effect of combining VA+CLA on 2-AG relative to VA alone (P> 0.05). Interestingly, VA increased jejunal concentrations of anandamide and those of the noncannabinoid signaling molecules, oleoylethanolamide and palmitoylethanolamide, relative to control diet (P< 0.05). This was consistent with a lower jejunal protein abundance (but not activity) of their degrading enzyme, fatty acid amide hydrolase, as well as the mRNA expression of TNFα and interleukin 1ß (P< 0.05). The ability of VA to reduce 2-AG in the liver and VAT provides a potential mechanistic explanation to alleviate ectopic lipid accumulation. The opposing regulation of ECs and other noncannabinoid lipid signaling molecules by VA suggests an activation of benefit via the EC system in the intestine.

Down-regulation of hypothalamic pro-opiomelanocortin (POMC) expression after weaning is associated with hyperphagia-induced obesity in JCR rats overexpressing neuropeptide Y.

We hypothesised that hypothalamic feeding-related neuropeptides are differentially expressed in obese-prone and lean-prone rats and trigger overeating-induced obesity. To test this hypothesis, in the present study, we measured energy balance and hypothalamic neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) mRNA expressions in male JCR:LA-cp rats. We compared, in independent cohorts, free-feeding obese-prone (Obese-FF) and lean-prone (Lean-FF) rats at pre-weaning (10 d old), weaning (21-25 d old) and early adulthood (8-12 weeks). A group of Obese-pair-feeding (PF) rats pair-fed to the Lean-FF rats was included in the adult cohort. The body weights of 10-d-old Obese-FF and Lean-FF pups were not significantly different. However, when the pups were shifted from dams' milk to solid food (weaning), the obese-prone rats exhibited more energy intake over the days than the lean-prone rats and higher body and fat pad weights and fasting plasma glucose, leptin, insulin and lipid levels. These differences were consistent with higher energy consumption and lower energy expenditure. In the young adult cohort, the differences between the Obese-FF and Lean-FF rats became more pronounced, yielding significant age effects on most of the parameters of the metabolic syndrome, which were reduced in the Obese-PF rats. The obese-prone rats displayed higher NPY expression than the lean-prone rats at pre-weaning and weaning, and the expression levels did not differ by age. In contrast, POMC expression exhibited significant age-by-genotype differences. At pre-weaning, there was no genotype difference in POMC expression, but in the weanling cohort, obese-prone pups exhibited lower POMC expression than the lean-prone rats. This genotype difference became more pronounced at adulthood. Overall, the development of hyperphagia-induced obesity in obese-prone JCR rats is related to POMC expression down-regulation in the presence of established NPY overexpression.

Endoplasmic reticulum stress in pancreatic ß-cell dysfunctionality and diabetes mellitus: a promising target for generation of functional hPSC-derived ß-cells in vitro.

Diabetes mellitus (DM), is a chronic disorder characterized by impaired glucose homeostasis that results from the loss or dysfunction of pancreatic ß-cells leading to type 1 diabetes (T1DM) and type 2 diabetes (T2DM), respectively. Pancreatic ß-cells rely to a great degree on their endoplasmic reticulum (ER) to overcome the increased secretary need for insulin biosynthesis and secretion in response to nutrient demand to maintain glucose homeostasis in the body. As a result, ß-cells are potentially under ER stress following nutrient levels rise in the circulation for a proper pro-insulin folding mediated by the unfolded protein response (UPR), underscoring the importance of this process to maintain ER homeostasis for normal ß-cell function. However, excessive or prolonged increased influx of nascent proinsulin into the ER lumen can exceed the ER capacity leading to pancreatic ß-cells ER stress and subsequently to ß-cell dysfunction. In mammalian cells, such as ß-cells, the ER stress response is primarily regulated by three canonical ER-resident transmembrane proteins: ATF6, IRE1, and PERK/PEK. Each of these proteins generates a transcription factor (ATF4, XBP1s, and ATF6, respectively), which in turn activates the transcription of ER stress-inducible genes. An increasing number of evidence suggests that unresolved or dysregulated ER stress signaling pathways play a pivotal role in ß-cell failure leading to insulin secretion defect and diabetes. In this article we first highlight and summarize recent insights on the role of ER stress and its associated signaling mechanisms on ß-cell function and diabetes and second how the ER stress pathways could be targeted in vitro during direct differentiation protocols for generation of hPSC-derived pancreatic ß-cells to faithfully phenocopy all features of bona fide human ß-cells for diabetes therapy or drug screening.

Risk Factors Associated with Opportunistic Infections among People Living with HIV/AIDS and Receiving an Antiretroviral Therapy in Gabon, Central Africa.

The Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) is still one of the main causes of death in sub-Saharan Africa. Antiretroviral therapies (ARTs) have significantly improved the health conditions of people living with HIV/AIDS (PLWHA). Consequently, a significant drop in morbidity and mortality, along with a reduced incidence of opportunistic infections (OIs), has been observed. However, certain atypical and biological profiles emerge in ART patients post-examination. The objective of this study was to identify the risk factors that contributed to the onset of OIs in HIV patients undergoing ART in Gabon. Epidemiological and biological data were obtained from medical records (2017 to 2019) found at the outpatient treatment centre (CTA) of Franceville in Gabon. Samples for blood count, CD4, and viral load analysis at CIRMF were collected from PLWHA suffering from other pathogen-induced conditions. A survey was carried out and data were analysed using Rstudio 4.0.2 and Excel 2007 software. Biological and socio-demographic characteristics were examined concerning OIs through both a univariate analysis via Fisher's exact tests or chi2 (χ2), and a multivariate analysis via logistic regression. Out of the 300 participants initially selected, 223 were included in the study, including 154 (69.05%) women and 69 (30.95%) men. The mean age was 40 (38.6; 41.85), with individuals ranging from 2 to 77 years old. The study cohort was classified into five age groups (2 to 12, 20 to 29, 30 to 39, 40 to 49, and 50 to 77 years old), among which the groups aged 30 to 39 and 40 to 49 emerged as the largest, comprising 68 (30.5%) and 75 (33.6%) participants, respectively. It was noted that 57.9% of PLWHA had developed OIs and three subgroups were distinguished, with parasitic, viral, and bacterial infections present in 18%, 39.7%, and 55.4% of cases, respectively. There was a correlation between being male and having a low CD4 T-cell count and the onset of OIs. The study revealed a high overall prevalence of OIs, and extending the study to other regions of Gabon would yield a better understanding of the risk factors associated with the onset of these infections.