Artemisinins Target GABAA Receptor Signaling and Impair α Cell Identity.

Type 1 diabetes is characterized by the destruction of pancreatic ß cells, and generating new insulin-producing cells from other cell types is a major aim of regenerative medicine. One promising approach is transdifferentiation of developmentally related pancreatic cell types, including glucagon-producing α cells. In a genetic model, loss of the master regulatory transcription factor Arx is sufficient to induce the conversion of α cells to functional ß-like cells. Here, we identify artemisinins as small molecules that functionally repress Arx by causing its translocation to the cytoplasm. We show that the protein gephyrin is the mammalian target of these antimalarial drugs and that the mechanism of action of these molecules depends on the enhancement of GABAA receptor signaling. Our results in zebrafish, rodents, and primary human pancreatic islets identify gephyrin as a druggable target for the regeneration of pancreatic ß cell mass from α cells.

Facilitators and barriers of women's participation in HIV clinical research in Switzerland: A qualitative study.

OBJECTIVES: Women are underrepresented in most HIV clinical trials in Western countries, but their participation remains crucial as the lack of information on sex- and gender-specific effects may hinder the safety and efficacy of antiretroviral treatments. The aim of this study was to identify barriers to and facilitators of women's participation in HIV clinical trials in Switzerland. METHODS: We conducted semi-structured interviews among 20 women with HIV to explore factors associated with non-participation in clinical trials. The interviewer presented to participants a clinical trial's description and discussed it with them. Lexicometric analysis on transcribed interviews identified three themes and eight sub-themes related to the pros and cons of participation in HIV clinical trials. RESULTS: Participants evoked mainly decision-making drivers, concerns for women living with HIV and treatment side-effects. They highlighted the need for extensive information provided by trusted healthcare professionals on the research process as central to the decision to enrol in HIV clinical trials. Familial responsibilities were clearly identified as barriers to their participation, but not pregnancy. Additional preoccupations were other health concerns and comorbidities and the consequences of stopping ongoing antiretroviral treatments. CONCLUSIONS: To overcome the barriers to the participation of women living with HIV in clinical research in Western countries, healthcare professionals and researchers should increase women's research literacy by involving them in the study design and by tailoring clinical trials to their social roles and health concerns. Trust in professionals is a facilitator of enrolment of women living with HIV that should be maintained.

Pharmacokinetic parameters and weight change in HIV patients newly switched to dolutegravir-based regimens in SIMPL'HIV clinical trial.

This study aims to evaluate the association between dolutegravir (DTG) pharmacokinetic parameters and weight changes in treatment-experienced people with HIV (PWHIV) from the Simpl'HIV study newly switched to a dual DTG-based regimen. We used multivariable linear regressions to evaluate the association between DTG pharmacokinetic parameters at week 48 (derived using an established model) and weight change between week 0 and week 48. We adjusted our model for potential confounders including CD4 nadir, female sex, African origin, age, weight at week 0 and presence of a non-nucleoside reverse transcriptase inhibitor-based regimen before switch to DTG. The analysis included data from 39 PWHIV. An average significant weight gain of 2.4 kg was observed between baseline and week 48. DTG plasma exposure was not significantly associated with weight gain, even after adjusting for potential confounders (P = .9). We found no significant association between DTG pharmacokinetic parameters and weight gain amongst PWHIV newly switched to a DTG-based dual regimen.

Single-cell transcriptomes reveal characteristic features of human pancreatic islet cell types.

Pancreatic islets of Langerhans contain several specialized endocrine cell types, which are commonly identified by the expression of single marker genes. However, the established marker genes cannot capture the complete spectrum of cellular heterogeneity in human pancreatic islets, and existing bulk transcriptome datasets provide averages across several cell populations. To dissect the cellular composition of the human pancreatic islet and to establish transcriptomes for all major cell types, we performed single-cell RNA sequencing on 70 cells sorted from human primary tissue. We used this dataset to validate previously described marker genes at the single-cell level and to identify specifically expressed transcription factors for all islet cell subtypes. All data are available for browsing and download, thus establishing a useful resource of single-cell expression profiles for endocrine cells in human pancreatic islets.

Cell rearrangement in transplanted human islets.

The major feature of the human pancreatic islet architecture is the organization of endocrine cells into clusters comprising central ß cells and peripheral α cells surrounded by vasculature. To have an insight into the mechanisms that govern this unique islet architecture, islet cells were isolated, and reaggregation of α and ß cells into islet-like structures (pseudoislets) after culture or transplantation into mice was studied by immunohistology. The pseudoislets formed in culture displayed an unusual cell arrangement, contrasting with the transplanted pseudoislets, which exhibited a cell arrangement similar to that observed in native pancreatic islet subunits. The pattern of revascularization and the distribution of extracellular matrix around transplanted pseudoislets were alike to those observed in native pancreatic islets. This organization of transplanted pseudoislets occurred also when revascularization was abolished by treating mice with an anti-VEGF antibody, but not when contact with extracellular matrix was prevented by encapsulation of pseudoislets within alginate hydrogel. These results indicate that the maintenance of islet cell arrangement is dependent on in vivo features such as extracellular matrix but independent of vascularization.

Brief Report: Representations and Willingness of People Living With HIV in Switzerland to Participate in HIV Cure Trials: The Case of Gene-Modified Cell Therapies.

BACKGROUND: Recent advances made in cell and gene therapies for cancer suggest that they represent plausible strategies to cure HIV. However, the health risks and constraints associated with these therapies require a deeper understanding of the expectations of such treatments among people living with HIV (PLWH). METHODS: We conducted 15 semistructured in-depth interviews among patients from 2 HIV units in Switzerland. After a conversation about their perceptions of research on HIV therapies, participants were provided with a trial description using a gene-modified cell therapy as a potentially curative approach. They were invited to discuss how they might consider participation in the trial. Content analysis was performed to identify core themes. RESULTS: Participants perceived the trial as burdensome and uncertain. Most were aware that cure was not guaranteed, and 6 of the 15 considered that they would participate. Two main concerns were expressed about potential participation: (1) the impact on the professional life and fear to be stigmatized because of this and (2) the fact that stopping antiretroviral treatment would challenge the balance currently achieved in their lives. The decision to participate would depend on their understanding of the trial, the availability of sufficient information, and the relationship with health care professionals. CONCLUSION: Involving PLWH in early stages of research would be crucial to improve their understanding of gene-modified cell therapies. It could also help adapt trials to address key factors, including the anticipation of stigma, which may discourage PLWH from participating in treatment research.

An inhibitor-mediated beta-cell dedifferentiation model reveals distinct roles for FoxO1 in glucagon repression and insulin maturation.

OBJECTIVE: The loss of forkhead box protein O1 (FoxO1) signaling in response to metabolic stress contributes to the etiology of type II diabetes, causing the dedifferentiation of pancreatic beta cells to a cell type reminiscent of endocrine progenitors. Lack of methods to easily model this process in vitro, however, have hindered progress into the identification of key downstream targets and potential inhibitors. We therefore aimed to establish such an in vitro cellular dedifferentiation model and apply it to identify novel agents involved in the maintenance of beta-cell identity. METHODS: The murine beta-cell line, Min6, was used for primary experiments and high-content screening. Screens encompassed a library of small-molecule drugs representing the chemical and target space of all FDA-approved small molecules with an automated immunofluorescence readout. Validation experiments were performed in a murine alpha-cell line as well as in primary murine and human diabetic islets. Developmental effects were studied in zebrafish and C. elegans models, while diabetic db/db mouse models were used to elucidate global glucose metabolism outcomes. RESULTS: We show that short-term pharmacological FoxO1 inhibition can model beta-cell dedifferentiation by downregulating beta-cell-specific transcription factors, resulting in the aberrant expression of progenitor genes and the alpha-cell marker glucagon. From a high-content screen, we identified loperamide as a small molecule that can prevent FoxO inhibitor-induced glucagon expression and further stimulate insulin protein processing and secretion by altering calcium levels, intracellular pH, and FoxO1 localization. CONCLUSIONS: Our study provides novel models, molecular targets, and drug candidates for studying and preventing beta-cell dedifferentiation.

Beta-Cell-Specific Expression of Nicotinamide Adenine Dinucleotide Phosphate Oxidase 5 Aggravates High-Fat Diet-Induced Impairment of Islet Insulin Secretion in Mice.

Aims: Nicotinamide adenine dinucleotide phosphate oxidases (NOX-es) produce reactive oxygen species and modulate ß-cell insulin secretion. Islets of type 2 diabetic subjects present elevated expression of NOX5. Here, we sought to characterize regulation of NOX5 expression in human islets in vitro and to uncover the relevance of NOX5 in islet function in vivo using a novel mouse model expressing NOX5 in doxycycline-inducible, ß-cell-specific manner (RIP/rtTA/NOX5 mice). Results:In situ hybridization and immunohistochemistry employed on pancreatic sections demonstrated NOX5 messenger ribonucleic acid (mRNA) and protein expressions in human islets. In cultures of dispersed islets, NOX5 protein was observed in somatostatin-positive (δ) cells in basal (2.8 mM glucose) conditions. Small interfering ribonucleic acid (siRNA)-mediated knockdown of NOX5 in human islets cultured in basal glucose concentrations resulted in diminished glucose-induced insulin secretion (GIIS) in vitro. However, when islets were preincubated in high (16.7 mM) glucose media for 12 h, NOX5 appeared also in insulin-positive (ß) cells. In vivo, mice with ß-cell NOX5 expression developed aggravated impairment of GIIS compared with control mice when challenged with 14 weeks of high-fat diet. Similarly, in vitro palmitate preincubation resulted in more severe reduction of insulin release in islets of RIP/rtTA/NOX5 mice compared with their control littermates. Decreased insulin secretion was most distinct in response to theophylline stimulation, suggesting impaired cyclic adenosine monophosphate (cAMP)-mediated signaling due to increased phosphodiesterase activation. Innovation and Conclusions: Our data provide the first insight into the complex regulation and function of NOX5 in islets implying an important role for NOX5 in δ-cell-mediated intraislet crosstalk in physiological circumstances but also identifying it as an aggravating factor in ß-cell failure in diabetic conditions.

The Role of Inflammation in ß-cell Dedifferentiation.

Chronic inflammation impairs insulin secretion and sensitivity. ß-cell dedifferentiation has recently been proposed as a mechanism underlying ß-cell failure in T2D. Yet the effect of inflammation on ß-cell identity in T2D has not been studied. Therefore, we investigated whether pro-inflammatory cytokines induce ß-cell dedifferentiation and whether anti-inflammatory treatments improve insulin secretion via ß-cell redifferentiation. We observed that IL-1ß, IL-6 and TNFα promote ß-cell dedifferentiation in cultured human and mouse islets, with IL-1ß being the most potent one of them. In particular, ß-cell identity maintaining transcription factor Foxo1 was downregulated upon IL-1ß exposure. In vivo, anti-IL-1ß, anti-TNFα or NF-kB inhibiting sodium salicylate treatment improved insulin secretion of isolated islets. However, only TNFα antagonism partially prevented the loss of ß-cell identity gene expression. Finally, the combination of IL-1ß and TNFα antagonism improved insulin secretion of ex vivo isolated islets in a synergistic manner. Thus, while inflammation triggered ß-cell dedifferentiation and dysfunction in vitro, this mechanism seems to be only partly responsible for the observed in vivo improvements in insulin secretion.

Asymmetrical distribution of δ and PP cells in human pancreatic islets.

The aim of this study was to evaluate the location of PP and δ cells in relation to the vascularization within human pancreatic islets. To this end, pancreas sections were analysed by immunofluorescence using antibodies against endocrine islet and endothelial cells. Staining in different islet areas corresponding to islet cells adjacent or not to peripheral or central vascular channels was quantified by computerized morphometry. As results, α, PP and δ cells were preferentially found adjacent to vessels. In contrast to α cells, which were evenly distributed between islet periphery and intraislet vascular channels, PP and δ cells had asymmetric and opposite distributions: PP staining was higher and somatostatin staining was lower in the islet periphery than in the area around intraislet vascular channels. Additionally, frequencies of PP and δ cells were negatively correlated in the islets. No difference was observed between islets from the head and the tail of the pancreas, and from type 2 diabetic and non-diabetic donors. In conclusion, the distribution of δ cells differs from that of PP cells in human islets, suggesting that vessels at the periphery and at the centre of islets drain different hormonal cocktails.