Prolonged islet allograft function is associated with female sex in patients after islet transplantation

Background Islet transplantation (ITx) has proved to be effective in preventing severe hypoglycemia and improving metabolic control in selected subjects with T1D. Long-term graft function remains a challenge. Estrogens have been shown to protect β-cells from metabolic stresses and improve revascularization of transplanted human islets in the mouse. We aimed to evaluate the influence of sex in allograft survival of ITx recipients. Methods We analyzed a retrospective cohort of ITx recipients (n=56) followed-up for up to 20 years. Allograft failure was defined as a stimulated C-peptide <0.3 ng/ml during a mixed-meal tolerance test. Subjects were divided into recipients of at least one female donor (Group 1) and recipients of male donors only (Group 2). Results Group 1 subjects (n=25) were aged 41.5 ± 8.4 years and Group 2 subjects (n=22) 45.9 ± 7.3 years (P= 0.062). Female recipient frequency was 44.8% (n=13) in Group 1 and 55.2% (n=16) in Group 2 (P=0.145). Group 2 developed graft failure earlier than Group 1 [680 (286 – 1624) vs. 1906 (756 – 3256) days, P= 0.038]. We performed additional analyses on female recipients only from each group (Group 1, n= 16, Group 2, n=20). Female recipients in Group 1 exhibited prolonged allograft function compared to Group 2, after adjustment for confounders (OR: 28.6, CI: 1.3 – 619.1; P < 0.05). Conclusion Recipients of islets from at least one female donor exhibited prolonged graft survival compared to recipients of islets from exclusively male donors. In addition, female recipients exhibited prolonged survival compared to male recipients following ITx of at least one female donor.

Poverty and Pellagra’s Penumbras

Pellagra has largely been forgotten. This is unfortunate as important lessons are to be learnt about the diseases and social and economic consequences of poverty – and for the root cause of poverty (and of affluence) – that involve dietary nicotinamide and nicotinamide adenine dinucleotide (NAD) homeostasis. NAD disruption can occur not only from poor diet but from increased consumption from genotoxic, infectious and metabolic stresses. NAD deficiency is closely linked to poor physical and intellectual development, premature ageing and diseases of ageing. Acute infections, many with NAD-consuming toxins, that may differentially affect the NAD-depleted, now include COVID-19. Some Covid manifestations, such as myoclonic encephalopathy and “Long Covid,” resemble pellagra clinically and biochemically as both have disturbed nicotinic and tryptophan metabolism. Symbionts that supply nicotinic acid, such as TB and some gut micro-organisms, can become dysbiotic if the diet is very deficient in milk and meat, as it is for 1–2 billion or more. High doses of nicotinamide lead to inhibition of NAD-consuming enzymes and excessive induction of nicotinamide-n-methyl transferase (NNMT) with consequent effects on the methylome: this gives a mechanism for an unrecognised hypervitaminosis-B3 with adverse effects of nicotinamide overload for consumers on a high meat diet with “fortified” foods and “high energy” drinks. Methods of measuring NAD metabolism routinely for screening the populations at risk of deficiency and in metabolically ill or infectious disease patients should be developed urgently. Successful intervention should improve human capital and prevent many aspects of poverty, reduce discrimination and even the drive to emigrate.

Negative curvature-promoting lipids instruct nuclear ingression of low autophagic potential vacuoles

Membrane contact sites are functional nodes at which organelles exchange information through moving ions, proteins and lipids, thus driving the reorganization of metabolic pathways and the adaptation to changing cues. The nuclear-vacuole junction of Saccharomyces cerevisiae is among the most extensive and better-known organelle contact sites, described to expand in response to various metabolic stresses. While using genotoxins with unrelated purposes, we serendipitously discovered a phenomenon that we describe as the most extreme and intimate contact ever reported between nuclei and vacuoles: the vacuole becomes completely internalized in the nucleus. We define lipids supporting negative curvature, such as phosphatidic acid and sterols, as bona-fide drivers of this event. Functionally, we purport that internalized vacuoles are low efficiency ones whose removal from the cytoplasm optimizes cargo interaction with functional vacuoles. Thus, our findings also point to nucleus-vacuole interactions as important for metabolic adaptation. Yet, rather than by inter-organelle exchanges, the underlying mechanism literally concurs with vacuolar sequestration.

HspB4/αA-Crystallin Modulates Neuroinflammation in the Retina via the Stress-Specific Inflammatory Pathways

Purpose: We have previously demonstrated that HspB4/αA-crystallin, a molecular chaperone, plays an important intrinsic neuroprotective role during diabetes, by its phosphorylation on residue 148. We also reported that HspB4/αA-crystallin is highly expressed by glial cells. There is a growing interest in the potential causative role of low-grade inflammation in diabetic retinopathy pathophysiology and retinal Müller glial cells’ (MGCs’) participation in the inflammatory response. MGCs indeed play a central role in retinal homeostasis via secreting various cytokines and other mediators. Hence, this study was carried out to delineate and understand the regulatory function of HspB4/αA-crystallin in the inflammatory response associated with metabolic stresses. Methods: Primary MGCs were isolated from knockout HspB4/αA-crystallin mice. These primary cells were then transfected with plasmids encoding either wild-type (WT), phosphomimetic (T148D), or non-phosphorylatable mutants (T148A) of HspB4/αA-crystallin. The cells were exposed to multiple metabolic stresses including serum starvation (SS) or high glucose with TNF-alpha (HG + T) before being further evaluated for the expression of inflammatory markers by qPCR. The total protein expression along with subcellular localization of NF-kB and the NLRP3 component was assessed by Western blot. Results: Elevated levels of IL-6, IL-1β, MCP-1, and IL-18 in SS were significantly diminished in MGCs overexpressing WT and further in T148D as compared to EV. The HG + T-induced increase in these inflammatory markers was also dampened by WT and even more significantly by T148D overexpression, whereas T148A was ineffective in either stress. Further analysis revealed that overexpression of WT or the T148D, also led to a significant reduction of Nlrp3, Asc, and caspase-1 transcript expression in serum-deprived MGCs and nearly abolished the NF-kB induction in HG + T diabetes-like stress. This mechanistic effect was further evaluated at the protein level and confirmed the stress-dependent regulation of NLRP3 and NF-kB by αA-crystallin. Conclusions: The data gathered in this study demonstrate the central regulatory role of HspB4/αA-crystallin and its modulation by phosphorylation on T148 in retinal MGCs. For the first time, this study demonstrates that HspB4/αA-crystallin can dampen the stress-induced expression of pro-inflammatory cytokines through the modulation of multiple key inflammatory pathways, therefore, suggesting its potential as a therapeutic target for the modulation of chronic neuroinflammation.

The Role of AMPK Signaling in Brown Adipose Tissue Activation

Obesity is becoming a pandemic, and its prevalence is still increasing. Considering that obesity increases the risk of developing cardiometabolic diseases, research efforts are focusing on new ways to combat obesity. Brown adipose tissue (BAT) has emerged as a possible target to achieve this for its functional role in energy expenditure by means of increasing thermogenesis. An important metabolic sensor and regulator of whole-body energy balance is AMP-activated protein kinase (AMPK), and its role in energy metabolism is evident. This review highlights the mechanisms of BAT activation and investigates how AMPK can be used as a target for BAT activation. We review compounds and other factors that are able to activate AMPK and further discuss the therapeutic use of AMPK in BAT activation. Extensive research shows that AMPK can be activated by a number of different kinases, such as LKB1, CaMKK, but also small molecules, hormones, and metabolic stresses. AMPK is able to activate BAT by inducing adipogenesis, maintaining mitochondrial homeostasis and inducing browning in white adipose tissue. We conclude that, despite encouraging results, many uncertainties should be clarified before AMPK can be posed as a target for anti-obesity treatment via BAT activation.

Health effects of European colonization: An investigation of skeletal remains from 19th to early 20th-century migrant settlers in South Australia

Nineteenth century medical understanding of human metabolism was limited, therefore, the incidence of metabolic deficiencies was not fully recorded. In addition, the transition from agricultural based mode of life to the industrial one significantly changed the pattern of these metabolic deficiencies. They were further altered by colonization of distant continents. Palaeopathological study of skeletal remains from the early industrialized colonial-era allowed light to be shed on the metabolic stresses produced by this new mode of life. Aims of this study were to investigate manifestations of disease in skeletal remains from 65 (20 adults, 45 sub-adults) migrant settlers buried in the free ground of St Marys Anglican Church Cemetery (1847 to 1927). An area allocated for burials paid for by the South Australian Government. Skeletal manifestations were determined and interpreted in terms of their multiple aetiologies. Findings were compared with those published for two 19th century British samples. Skeletal manifestations, commonly related to metabolic deficiencies, were observed. Areas of abnormal porosity of bone cortices were seen in 9 adults and 12 sub-adults, flaring of metaphyses was seen in one sub-adult, flaring of costochondral junctions of the ribs was seen in one sub-adult. Porous lesions of orbital roof bones (Types 3 to 5) were seen on three sub-adults. Micro-CT scans of tooth samples located interglobular dentine in three individuals. Comparison of St Marys findings with St Martins, Birmingham, and St Peters, Wolverhampton, UK, showed more individuals from St Marys had areas of abnormal porosity of bone cortices possibly related to vitamin C deficiency. However, St Marys sample displayed fewer changes attributable to vitamin D deficiency as expected in a country with greater UV irradiation. This indicates that, although the early industrialization produced metabolic stresses, change of the environment through colonization of new continents altered the distribution of metabolic deficiencies.

Alternative oxidase encoded by sequence-optimized and chemically-modified RNA transfected into mammalian cells is catalytically active

Plants and other organisms, but not insects or vertebrates, express the auxiliary respiratory enzyme alternative oxidase (AOX) that bypasses mitochondrial respiratory complexes III and/or IV when impaired. Persistent expression of AOX from Ciona intestinalis in mammalian models has previously been shown to be effective in alleviating some metabolic stresses produced by respiratory chain inhibition while exacerbating others. This implies that chronic AOX expression may modify or disrupt metabolic signaling processes necessary to orchestrate adaptive remodeling, suggesting that its potential therapeutic use may be confined to acute pathologies, where a single course of treatment would suffice. One possible route for administering AOX transiently is AOX-encoding nucleic acid constructs. Here we demonstrate that AOX-encoding chemically-modified RNA (cmRNA), sequence-optimized for expression in mammalian cells, was able to support AOX expression in immortalized mouse embryonic fibroblasts (iMEFs), human lung carcinoma cells (A549) and primary mouse pulmonary arterial smooth muscle cells (PASMCs). AOX protein was detectable as early as 3 h after transfection, had a half-life of ~4 days and was catalytically active, thus supporting respiration and protecting against respiratory inhibition. Our data demonstrate that AOX-encoding cmRNA optimized for use in mammalian cells represents a viable route to investigate and possibly treat mitochondrial respiratory disorders.

Nutritional Orthopedics and Space Nutrition as Two Sides of the Same Coin: A Scoping Review

Since the Moon landing, nutritional research has been charged with the task of guaranteeing human health in space. In addition, nutrition applied to Orthopedics has developed in recent years, driven by the need to improve the efficiency of the treatment path by enhancing the recovery after surgery. As a result, nutritional sciences have specialized into two distinct fields of research: Nutritional Orthopedics and Space Nutrition. The former primarily deals with the nutritional requirements of old patients in hospitals, whereas the latter focuses on the varied food challenges of space travelers heading to deep space. Although they may seem disconnected, they both investigate similar nutritional issues. This scoping review shows what these two disciplines have in common, highlighting the mutual features between (1) pre-operative vs. pre-launch nutritional programs, (2) hospital-based vs. space station nutritional issues, and (3) post-discharge vs. deep space nutritional resilience. PubMed and Google Scholar were used to collect documents published from 1950 to 2020, from which 44 references were selected on Nutritional Orthopedics and 44 on Space Nutrition. Both the orthopedic patient and the astronaut were found to suffer from food insecurity, malnutrition, musculoskeletal involution, flavor/pleasure issues, fluid shifts, metabolic stresses, and isolation/confinement. Both fields of research aid the planning of demand-driven food systems and advanced nutritional approaches, like tailored diets with nutrients of interest (e.g., vitamin D and calcium). The nutritional features of orthopedic patients on Earth and of astronauts in space are undeniably related. Consequently, it is important to initiate close collaborations between orthopedic nutritionists and space experts, with the musculoskeletal-related dedications playing as common fuel.

Mitochondrial Carriers Regulating Insulin Secretion Profiled in Human Islets upon Metabolic Stress

Chronic exposure of β-cells to nutrient-rich metabolic stress impairs mitochondrial metabolism and its coupling to insulin secretion. We exposed isolated human islets to different metabolic stresses for 3 days: 0.4 mM oleate or 0.4 mM palmitate at physiological 5.5 mM glucose (lipotoxicity), high 25 mM glucose (glucotoxicity), and high 25 mM glucose combined with 0.4 mM oleate and/or palmitate (glucolipotoxicity). Then, we profiled the mitochondrial carriers and associated genes with RNA-Seq. Diabetogenic conditions, and in particular glucotoxicity, increased expression of several mitochondrial solute carriers in human islets, such as the malate carrier DIC, the α-ketoglutarate-malate exchanger OGC, and the glutamate carrier GC1. Glucotoxicity also induced a general upregulation of the electron transport chain machinery, while palmitate largely counteracted this effect. Expression of different components of the TOM/TIM mitochondrial protein import system was increased by glucotoxicity, whereas glucolipotoxicity strongly upregulated its receptor subunit TOM70. Expression of the mitochondrial calcium uniporter MCU was essentially preserved by metabolic stresses. However, glucotoxicity altered expression of regulatory elements of calcium influx as well as the Na+/Ca2+ exchanger NCLX, which mediates calcium efflux. Overall, the expression profile of mitochondrial carriers and associated genes was modified by the different metabolic stresses exhibiting nutrient-specific signatures.

FOXO activity adaptation safeguards the hematopoietic stem cell compartment in hyperglycemia

Hematopoietic stem cell (HSC) activity is tightly controlled to ensure the integrity of the hematopoietic system during the organism’s lifetime. How the HSC compartment maintains its long-term fitness in conditions of chronic stresses associated with systemic metabolic disorders is poorly understood. In this study, we show that obesity functionally affects the long-term function of the most immature engrafting HSC subpopulation. We link this altered regenerative activity to the oxidative stress and the aberrant constitutive activation of the AKT signaling pathway that characterized the obese environment. In contrast, we found minor disruptions of the HSC function in obese mice at steady state, suggesting that active mechanisms could protect the HSC compartment from its disturbed environment. Consistent with this idea, we found that FOXO proteins in HSCs isolated from obese mice become insensitive to their normal upstream regulators such as AKT, even during intense oxidative stress. We established that hyperglycemia, a key condition associated with obesity, is directly responsible for the alteration of the AKT-FOXO axis in HSCs and their abnormal oxidative stress response. As a consequence, we observed that HSCs isolated from a hyperglycemic environment display enhanced resistance to oxidative stress and DNA damage. Altogether, these results indicate that chronic metabolic stresses associated with obesity and/or hyperglycemia affect the wiring of the HSCs and modify their oxidative stress response. These data suggest that the uncoupling of FOXO from its environmental regulators could be a key adaptive strategy that promotes the survival of the HSC compartment in obesity.