Protein malnutrition potentiates the amplifying pathway of insulin secretion in adult obese mice

Fasting plasma glucose trends in the elderly living with HIV/AIDS on combination antiretroviral therapy regimens

BACKGROUND

With the ageing of people living with HIV/AIDS (PLWHA), the prevalence of chronic comorbidities, especially hyperglycaemia, is increasing among elderly PLWHA. Antiretroviral therapy (ART) is associated with fasting plasma glucose (FPG) levels. This study aimed to investigate both short-term and long-term FPG characteristics and trends across different ART regimens in elderly Chinese PLWHA.

METHODS

This retrospective cohort study, based on hospital treatment information, classified ART regimens as this retrospective cohort study used hospital treatment data. ART regimens are classified into three categories: non-nucleoside reverse transcriptase inhibitors (NNRTIs) based, protease inhibitors (PIs) based and integrase strand transfer inhibitor (INSTIs) based. Propensity score matching was applied to control for confounding factors. Follow-up FPG characteristics were then described, and a generalised linear mixed model was employed to estimate FPG trends under different regimens within 1-year and 5-year periods following ART initiation.

RESULTS

Participants had an average age of 58.28 years, with 75.02% male. FPG increased following ART initiation, with the most significant rise within 1 year of ART, followed by stabilisation. The FPG increase within 1 year was slower in the PIs-based group compared with the NNRTIs-based group (β=-0.08, 95% CI -0.15 to -0.01), while there was a higher prevalence of diabetes within 5 years of ART (31.55% vs 22.33%, standardised difference=0.357). The FPG increase within 1 year of ART did not differ between NNRTIs-based and INSTIs-based groups (β=-0.01, 95% CI -0.20, 0.18).

CONCLUSION

Our study highlights that elderly Chinese PLWHA experience an increase in FPG levels, particularly during the first year of ART, with variations observed across different ART regimens. The higher long-term prevalence of diabetes in the PIs-based regimen group emphasises the need for tailored glucose management strategies. Routine glucose monitoring and proactive management are crucial for preventing and controlling diabetes in this population, particularly given the long-term metabolic risks associated with ART.

Prevalence and Correlates of Double and Triple Burden of Malnutrition Among Children and Adolescents in India: The Comprehensive National Nutrition Survey

BACKGROUND

Limited information on the co-prevalence of undernutrition, micronutrient deficiencies, overnutrition, and abnormal levels of noncommunicable disease biomarkers at the same time in children and adolescents in India hinders efforts to comprehensively address their health.

OBJECTIVES

This study aimed to examine the prevalence and correlates of double burden of malnutrition (DBM) and triple burden of malnutrition (TBM) among children and adolescents (5-19 y) to inform policies and programs.

METHODS

A total of 17,599 children (5-9 y) and 16,184 adolescents (10-19 y) with available biomarker data from the Comprehensive National Nutrition Survey were included. Malnutrition was defined based on either undernutrition based on anthropometry, overnutrition/abnormal metabolic markers, and anemia/micronutrient deficiency. DBM was defined as the coexistence of any 2 forms of malnutrition. DBM+ was defined as the coexistence of undernutrition and/or micronutrient deficiency along with overnutrition. TBM was defined as having the coexistence of all 3 forms of malnutrition. The prevalence of DBM, DBM+, and TBM was estimated accounting for probabilistic selection. We used mixed-effect binomial regression to determine correlates of DBM/TBM in children and adolescents separately.

RESULTS

The prevalence of DBM, DBM+, and TBM was 50.8%, 37.2%, and 14.4%, respectively, in children and 53.4%, 36.1%, and 12.7%, respectively, in adolescents. The prevalence of DBM+ was significantly higher in girls compared to in boys in the 5-9 y age group. In children, being in a disadvantaged caste group, having a lower wealth index, having inadequate diet diversity, having no maternal schooling, and having a recent history of acute illness were associated with DBM. In adolescents, being in a disadvantaged caste group, maternal occupation, and lower paternal age were correlated with DBM. A similar set of variables was associated with TBM in both age groups.

CONCLUSIONS

The prevalence of DBM and TBM is substantial in children and adolescents in India and varies across states. Socioeconomic factors and acute illness were the main correlates for DBM and TBM.

Association between protein undernutrition and diabetes: Molecular implications in the reduction of insulin secretion

Undernutrition is still a recurring nutritional problem in low and middle-income countries. It is directly associated with the social and economic sphere, but it can also negatively impact the health of the population. In this sense, it is believed that undernourished individuals may be more susceptible to the development of non-communicable diseases, such as diabetes mellitus, throughout life. This hypothesis was postulated and confirmed until today by several studies that demonstrate that experimental models submitted to protein undernutrition present alterations in glycemic homeostasis linked, in part, to the reduction of insulin secretion. Therefore, understanding the changes that lead to a reduction in the secretion of this hormone is essential to prevent the development of diabetes in undernourished individuals. This narrative review aims to describe the main molecular changes already characterized in pancreatic β cells that will contribute to the reduction of insulin secretion in protein undernutrition. So, it will provide new perspectives and targets for postulation and action of therapeutic strategies to improve glycemic homeostasis during this nutritional deficiency.

Geriatric nutritional risk index is correlated with islet function but not insulin resistance in elderly patients with type 2 diabetes: A retrospective study

The geriatric nutritional risk index (GNRI) is a simple nutritional assessment tool that can predict poor prognosis in elderly subjects. The aim of this study was to evaluate the association between GNRI and both islet function and insulin sensitivity in patients with type 2 diabetes mellitus. This research carries significant implications for the integrated treatment and nutritional management of this patient population. A total of 173 patients with type 2 diabetes mellitus, aged 60 years or older, who were hospitalized in the Endocrinology Department at Hebei General Hospital from February 2018 to June 2021, were selected as the research subjects. These subjects were divided into 4 groups according to the quartile of their GNRI values: T1 (GNRI < 99.4, n = 43), T2 (99.4 ≤ GNRI < 103, n = 43), T3 (103 ≤ GNRI < 106.3, n = 43), and T4 (GNRI ≥ 106.3, n = 44). Glucose, insulin, and C-peptide concentrations were tested at 0, 30, 60, 120, and 180 minutes during a 75 g oral glucose tolerance test. The homeostasis model assessment for insulin resistance and the homeostasis model assessment for β cell function index were calculated. As the GNRI value increased, the levels of total protein, albumin, hemoglobin, alanine transaminase, aspartate aminotransferase, and 25-hydroxyvitamin D increased significantly. The area under the curve for blood glucose decreased significantly across the 4 groups, while the AUCs for insulin and C-peptide showed an overall increasing trend. β Cell function index increased significantly with the increase of GNRI; meanwhile, both the early-phase insulin secretion index and the late-phase insulin secretion index increased significantly. Although there was an increasing trend, homeostasis model assessment for insulin resistance did not change significantly among the 4 groups. This study indicates that elderly type 2 diabetes patients with higher nutritional risk have worse islet function, while insulin sensitivity is not associated with nutritional risk.

Effects of double burden malnutrition on energetic metabolism and glycemic homeostasis: A narrative review

Rapid changes in the food process led to greater consumption of ultra-processed foods which, associated with reduced physical activity, increased the number of overweight and obese individuals worldwide. However, in low and middle-income countries (LMICS) the growth of the obesity epidemic took place despite the high prevalence of undernutrition in children. This generated the coexistence of these two nutritional patterns, currently defined as double burden malnutrition (DBM). Several reports have already described the social, political, and economic aspects related to the causes and possible solutions for the control of DBM. Here, we highlight the metabolic alterations, related to fat deposition and glycemic homeostasis, described in experimental models of DBM and the differential effects of therapeutic strategies already tested. Therefore, this work aims to help the scientific community to understand how the DBM can lead to the development of obesity and type 2 diabetes through different mechanisms from traditional models of obesity and highlights the need to study these mechanisms and new therapeutic strategies to improve damages caused by DBM.

Amino acid restriction alters survival mechanisms in pancreatic beta cells: possible role of the PI3K/Akt pathway

Background and aims

Malnutrition in the early stages of life may lead to changes in the glycemic metabolism during adulthood, such as pancreatic beta cells dysfunction and failure. Therefore, this study aimed to evaluate the effects of an in vitro amino acid restriction model on the function and viability of pancreatic beta cells.

Methods

Insulin-producing cells (INS-1E) were maintained in control or amino acid restricted culture medium containing 1 × or 0.25 × of amino acids, respectively, for 48 h.

Results

Amino acid restricted group showed lower insulin secretion and insulin gene expression, reduced mitochondrial oxygen consumption rate and reactive oxygen species production. Besides, amino acid restricted group also showed higher levels of endoplasmic reticulum stress and apoptosis markers and enhanced Akt phosphorylation. However, even with higher levels of apoptosis markers, amino acid restricted group did not show higher levels of cell death unless the PI3K/Akt pathway was inhibited.

Conclusion

Amino acid restricted beta cell viability seems to be dependent on the PI3K/Akt pathway.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02568-2.

Amino acid restriction increases β-cell death under challenging conditions

Malnutrition programs metabolism, favor dysfunction of β cells. We aimed to establish an in vitro protocol of malnutrition, assessing the effect of amino acid restriction upon the β cells. Insulin-producing cells INS-1E and pancreatic islets were maintained in RPMI 1640 medium containing 1× (Ctl) or 0.25× (AaR) of amino acids. We evaluated several markers of β-cell function and viability. AaR Insulin secretion was reduced, whereas cell viability was unaltered. Calcium oscillations in response to glucose increased in AaR. AaR showed lower Ins1 RNAm, snap 25, and PKC (protein kinase C) protein content, whereas phospho-eIF2α was increased. AaR cells exposed to nutrient or chemical challenges displayed higher apoptosis rates. We showed that amino acid restriction programmed β cell and induced functional changes. This model might be useful for the study of molecular mechanisms involved with β-cell programming helping to establish novel therapeutic targets to prevent harmful outcomes of malnutrition.

Diet-induced glucose homeostasis dysregulation is enhanced by taurine supplementation in ovariectomized mice

Low levels of estrogens are associated with obesity-related comorbidities. Mice with lower levels of estrogens are thereby more sensitive to the effects of a high-fat-diet (HFD) for the development of glucose intolerance and insulin resistance. Studies in vivo have demonstrated that taurine (TAU) supplementation prevents glucose and insulin resistance. Thus, we aimed to investigate the potential beneficial effects of TAU supplementation on glucose homeostasis of mice with low levels of estrogens fed with a HFD. 3-month-old female C57BL/6J mice underwent bilateral ovariectomy (OVX). After 1 week of recovery, mice were divided into 4 groups and either received: a standard chow diet (OVXC), chow diet plus drinking water enriched with 3% of TAU (OVXCT), HFD (OVXH), and HFD plus supplementation of TAU (OVXHT) for 14 weeks. Exposure to the HFD increased adiposity and plasma levels of glucose and insulin. Contrary to our prediction, the addition of TAU enhanced the deleterious effects of the HFD. Glucose and insulin tolerance tests (ipGTT and ipITT) indicated that mice maintained on the HFD + TAU had worse glucose intolerance and insulin resistance that was linked to lower insulin signaling in skeletal muscle and liver. Insulin secretion of isolated pancreatic islets of OVXH mice was higher than OVXC, and the addition of TAU associated with a HFD did not modulate insulin secretion, suggesting a failure of pancreatic β cells of OVXHT mice. These results suggest that despite the beneficial reports of TAU, it should be used cautiously in situations where the levels of estrogens are low.

Vagotomy Reduces Insulin Clearance in Obese Mice Programmed by Low-Protein Diet in the Adolescence

The aim of this study was to investigate the effect of subdiaphragmatic vagotomy on insulin sensitivity, secretion, and degradation in metabolic programmed mice, induced by a low-protein diet early in life, followed by exposure to a high-fat diet in adulthood. Weaned 30-day-old C57Bl/6 mice were submitted to a low-protein diet (6% protein). After 4 weeks, the mice were distributed into three groups: LP group, which continued receiving a low-protein diet; LP + HF group, which started to receive a high-fat diet; and LP + HFvag group, which underwent vagotomy and also was kept at a high-fat diet. Glucose-stimulated insulin secretion (GSIS) in isolated islets, ipGTT, ipITT, in vivo insulin clearance, and liver expression of the insulin-degrading enzyme (IDE) was accessed. Vagotomy improved glucose tolerance and reduced insulin secretion but did not alter adiposity and insulin sensitivity in the LP + HFvag, compared with the LP + HF group. Improvement in glucose tolerance was accompanied by increased insulinemia, probably due to a diminished insulin clearance, as judged by the lower C-peptide : insulin ratio, during the ipGTT. Finally, vagotomy also reduced liver IDE expression in this group. In conclusion, when submitted to vagotomy, the metabolic programmed mice showed improved glucose tolerance, associated with an increase of plasma insulin concentration as a result of insulin clearance reduction, a phenomenon probably due to diminished liver IDE expression.

Protein malnutrition blunts the increment of taurine transporter expression by a high-fat diet and impairs taurine reestablishment of insulin secretion

Taurine (Tau) restores β-cell function in obesity; however, its action is lost in malnourished obese rodents. Here, we investigated the mechanisms involved in the lack of effects of Tau in this model. C57BL/6 mice were fed a control diet (CD) (14% protein) or a protein-restricted diet (RD) (6% protein) for 6 wk. Afterward, mice received a high-fat diet (HFD) for 8 wk [CD + HFD (CH) and RD + HFD (RH)] with or without 5% Tau supplementation after weaning on their drinking water [CH + Tau (CHT) and RH + Tau (RHT)]. The HFD increased insulin secretion through mitochondrial metabolism in CH and RH. Tau prevented all those alterations in CHT only. The expression of the taurine transporter (Tau-T), as well as Tau content in pancreatic islets, was increased in CH but had no effect on RH. Protein malnutrition programs β cells and impairs Tau-induced restoration of mitochondrial metabolism and biogenesis. This may be associated with modulation of the expression of Tau-T in pancreatic islets, which may be responsible for the absence of effect of Tau in protein-malnourished obese mice.-Branco, R. C. S., Camargo, R. L., Batista, T. M., Vettorazzi, J. F., Borck, P. C., dos Santos-Silva, J. C. R., Boschero, A. C., Zoppi, C. C., Carneiro, E. M. Protein malnutrition blunts the increment of taurine transporter expression by a high-fat diet and impairs taurine reestablishment of insulin secretion.

Mechanisms of the amplifying pathway of insulin secretion in the β cell

Pancreatic islet β cells secrete insulin in response to nutrient secretagogues, like glucose, dependent on calcium influx and nutrient metabolism. One of the most intriguing qualities of β cells is their ability to use metabolism to amplify the amount of secreted insulin independent of further alterations in intracellular calcium. Many years studying this amplifying process have shaped our current understanding of β cell stimulus-secretion coupling; yet, the exact mechanisms of amplification have been elusive. Recent studies utilizing metabolomics, computational modeling, and animal models have progressed our understanding of the metabolic amplifying pathway of insulin secretion from the β cell. New approaches will be discussed which offer in-roads to a more complete model of β cell function. The development of β cell therapeutics may be aided by such a model, facilitating the targeting of aspects of the metabolic amplifying pathway which are unique to the β cell.

Assessment of Insulin Sensitivity and its Convalescence with Dietary Rehabilitation in Undernourished Rural West Bengal Population

INTRODUCTION

Metabolic syndrome involving diabetes is acquiring the eminence of prospective epidemic in India with dramatic rise in rural population prevalence where majority are undernourished and creates significant healthcare burden.

AIM

To investigate the prevalence of the insulin resistance amongst the undernourished rural population, involving children, adolescents and adult volunteers of the West Bengal and the effect of nutritional supplementation in the parameters echoing insulin sensitivity.

MATERIALS AND METHODS

A prospective interventional study was carried out on 120 volunteers in three age groups; Group 1 (5-12 years), Group 2 (13-18 years) and Group 3 (19-40 years), each with 40 subjects who fulfilled the inclusion criteria, under informed consent over six months. Baseline data regarding demography, family history including parental history of diabetes, medical history, physical, activity, anthropometrical status and blood parameters echoing insulin sensitivity were obtained from volunteers. Intervention included daily nutritional supplementation with eggs and banana. After six months of food supplementation, parameters reflecting insulin sensitivity were assessed.

RESULTS

Initial low figures of fasting insulin and blood sugar levels improvised with the nutritional supplementation alongside the absence of wasting in Group 1. HOMA-IR and IRI values of the Group 2 improved from the initial figures (3.19, 2.87) to (2.204, 1.99) and that of Group 3 from (5.0, 4.52) to (4.08, 3.67) respectively over six months (p<.05). Average Fasting Blood Sugar (FBS) enhanced from 85.5±9.6 mg/dl to 78.4±7.3 mg/dl and from 90.1±10.2 mg/dl to 84.8±8.4 mg/dl in Group 2 and 3 respectively by the end of the supplementation study (p<.05).

CONCLUSION

Six months study revealed the existence of insulin resistance and malnourishment in the selected rural population in three groups. Decrement in HOMA-IR, IRI, FBS and serum insulin alongside the improvement in the body mass, in comparison to that of initial values is evocative of restoration of insulin sensitivity with nutrition supplementation.