Maternal physical activity and sitting time and its association with placental morphology and blood flow during gestation: Findings from the Queensland Family Cohort study

OBJECTIVES

Antenatal exercise is associated with placental morphological alterations, however research in this area is limited. Given the emphasis on the beneficial effects of antenatal exercise, it is important to understand its effect on placental function and the relationship to foetal development. The aim of this study was to investigate the association between physical activity, sitting time, and placental outcomes measured during gestation.

DESIGN

Prospective cohort study.

METHODS

Pregnant women in the Queensland Family Cohort study self-reported physical activity at 24 and 36 weeks of gestation (n = 203) and were categorised into physical activity volume groups of nil-low (0-<500 metabolic equivalent of task·minutes/week), moderate (500-<1000 metabolic equivalent of task·minutes/week), or high-volume activity (≥1000 metabolic equivalent of task·minutes/week). Participants reported average daily sitting time, whereby excessive sitting time was considered as ≥8h/day. Placental stiffness, thickness, and uteroplacental blood flow resistance were measured by ultrasound imaging at each timepoint.

RESULTS

Physical activity volume was not associated with changes to placental morphometrics or uteroplacental blood flow resistance at 24 or 36 weeks of gestation. Excessive sitting time at 36 weeks was associated with greater placental stiffness (p = 0.046), and a lower umbilical artery pulsatility index (p = 0.001).

CONCLUSIONS

Placental tissue stiffness and umbilical artery resistance were altered in late gestation with higher maternal sitting time but not with physical activity volume. Overall, excessive sitting time may be a risk for suboptimal placental function and could be an important focus for antenatal care.

Barriers and facilitators for recruiting and retaining male participants into longitudinal health research: a systematic review

BACKGROUND

Successfully recruiting male participants to complete a healthcare related study is important for healthcare study completion and to advance our clinical knowledgebase. To date, most research studies have examined the barriers and facilitators of female participants in longitudinal healthcare-related studies with limited information available about the needs of males in longitudinal research. This systematic review examines the unique barriers and facilitators to male recruitment across longitudinal healthcare-related research studies.

METHODS

Following PRIMSA guidelines, MEDLINE, Embase, CINAHL and Web of Science databases were systematically searched using the terms recruitment and/or retention, facilitators and/or barriers and longitudinal studies from 1900 to 2023 which contained separate data on males aged 17-59 years. Health studies or interventions were defined longitudinal if they were greater than or equal to 12 weeks in duration with 3 separate data collection visits.

RESULTS

Twenty-four articles published from 1976-2023 met the criteria. One-third of the studies had a predominantly male sample and four studies recruited only male participants. Males appear disinterested towards participation in health research, however this lack of enthusiasm can be overcome by clear, non-directive communication, and studies that support the participants interests. Facilitating factors are diverse and may require substantial time from research teams.

CONCLUSIONS

Future research should focus on the specific impact of these factors across the spectrum of longitudinal health-related studies. Based on the findings of this systematic review, researchers from longitudinal health-related clinical trials are encouraged to consider male-specific recruitment strategies to ensure successful recruitment and retention in their studies.

REGISTRATION

This systemic review is registered with the PROSPERO database (CRD42021254696).

Dietary supplements, guideline alignment and biochemical nutrient status in pregnancy: Findings from the Queensland Family Cohort pilot study

In high-income nations, multiple micronutrient (MMN) supplementation during pregnancy is a common practice. We aimed to describe maternal characteristics associated with supplement use and daily dose of supplemental nutrients consumed in pregnancy, and whether guideline alignment and nutrient status are related to supplement use. The Queensland Family Cohort is a prospective, Australian observational longitudinal study. Maternal characteristics, nutrient intake from food and supplements, and biochemical nutrient status were assessed in the second trimester (n = 127). Supplement use was reported by 89% of participants, of whom 91% reported taking an MMN supplement. Participants who received private obstetric care, had private health insurance and had greater alignment to meat/vegetarian alternatives recommendations were more likely to report MMN supplement use. Private obstetric care and general practitioner shared care were associated with higher daily dose of supplemental nutrients consumed compared with midwifery group practice. There was high reliance on supplements to meet nutrient reference values for folate, iodine and iron, but only plasma folate concentrations were higher in MMN supplement versus nonsupplement users. Exceeding the upper level of intake for folic acid and iron was more likely among combined MMN and individual supplement/s users, and associated with higher plasma concentrations of the respective nutrients. Given the low alignment with food group recommendations and potential risks associated with high MMN supplement use, whole food diets should be emphasized. This study confirms the need to define effective strategies for optimizing nutrient intake in pregnancy, especially among those most vulnerable where MMN supplement use may be appropriate.

Alpha cell receptor for advanced glycation end products associate with glucagon expression in type 1 diabetes

Hypoglycemia in type 1 diabetes associates with changes in the pancreatic islet α cells, where the receptor for advanced glycation end products (RAGE) is highly expressed. This study compared islet RAGE expression in donors without diabetes, those at risk of, and those with type 1 diabetes. Laser-dissected islets were subject to RNA bioinformatics and adjacent pancreatic tissue were assessed by confocal microscopy. We found that islets from type 1 diabetes donors had differential expression of the RAGE gene (AGER) and its correlated genes, based on glucagon expression. Random forest machine learning revealed that AGER was the most important predictor for islet glucagon levels. Conversely, a generalized linear model identified that glucagon expression could be predicted by expression of RAGE signaling molecules, its ligands and enzymes that create or clear RAGE ligands. Confocal imaging co-localized RAGE, its ligands and signaling molecules to the α cells. Half of the type 1 diabetes cohort comprised of adolescents and a patient with history of hypoglycemia-all showed an inverse relationship between glucagon and RAGE. These data confirm an association between glucagon and islet RAGE, its ligands and signaling pathways in type 1 diabetes, which warrants functional investigation into a role for RAGE in hypoglycemia.

Shear wave velocity measurement of the placenta is not limited by placental location

INTRODUCTION

Ultrasound elastography shows diagnostic promise via the non-invasive determination of placental elastic properties. A limitation is a potential for inadequate measurements from posterior placentae. This study aimed to analyse placental position's influence on measures of shear wave elastography (SWV).

METHODS

SWV elastography measurements were obtained via ultrasound at 24, 28 and 36 weeks gestation from 238 pregnancies. . The placental position was labelled as either anterior, posterior or fundal/lateral. Average SWV measurements (m/s) and the corresponding standard deviations (SD) were used for data analysis.

RESULTS

There was a statistically significant difference between SWV recorded from anterior (1.33 ± 0.19)m/s and posterior (1.39 ± 0.18)m/s placentae (p < 0.001). However, the average sampling depth between these groups was significantly different (3.98 cm vs. 5.38 cm, p < 0.001). There was no statistically significant difference between SWV when measurements were compared at similar depths, regardless of placental location. The addition of placental position to a previously developed mixed-effects model confirmed placental position did not result in improved SWV measurements. In this model, sampling depth remained the best predictor for SWV.

CONCLUSIONS

This study showed that placental position does not influence the accuracy or reliability of SWV.

Soluble RAGE Prevents Type 1 Diabetes Expanding Functional Regulatory T Cells

Type 1 diabetes is an autoimmune disease with no cure, where clinical translation of promising therapeutics has been hampered by the reproducibility crisis. Here, short-term administration of an antagonist to the receptor for advanced glycation end products (sRAGE) protected against murine diabetes at two independent research centers. Treatment with sRAGE increased regulatory T cells (Tregs) within the islets, pancreatic lymph nodes, and spleen, increasing islet insulin expression and function. Diabetes protection was abrogated by Treg depletion and shown to be dependent on antagonizing RAGE with use of knockout mice. Human Tregs treated with a RAGE ligand downregulated genes for suppression, migration, and Treg homeostasis (FOXP3, IL7R, TIGIT, JAK1, STAT3, STAT5b, CCR4). Loss of suppressive function was reversed by sRAGE, where Tregs increased proliferation and suppressed conventional T-cell division, confirming that sRAGE expands functional human Tregs. These results highlight sRAGE as an attractive treatment to prevent diabetes, showing efficacy and reproducibility at multiple research centers and in human T cells.

Kidney disease risk factors do not explain impacts of low dietary protein on kidney function and structure

The kidneys balance many byproducts of the metabolism of dietary components. Previous studies examining dietary effects on kidney health are generally of short duration and manipulate a single macronutrient. Here, kidney function and structure were examined in C57BL/6J mice randomized to consume one of a spectrum of macronutrient combinations (protein [5%–60%], carbohydrate [20%–75%], and fat [20%–75%]) from weaning to late-middle age (15 months). Individual and interactive impacts of macronutrients on kidney health were modeled. Dietary protein had the greatest influence on kidney function, where chronic low protein intake decreased glomerular filtration rates and kidney mass, whereas it increased kidney immune infiltration and structural injury. Kidney outcomes did not align with cardiometabolic risk factors including glucose intolerance, overweight/obesity, dyslipidemia, and hypertension in mice with chronic low protein consumption. This study highlights that protein intake over a lifespan is an important determinant of kidney function independent of cardiometabolic changes.

•

Chronic high macronutrient intake from any source increases kidney function (GFR)

•

Low protein intake led to greater kidney tubular structural injury and inflammation

•

Lower protein intake decreased kidney mass and glomerular filtration capacity

•

Kidney outcomes did not align with longevity or cardiometabolic outcomes

Changes in placental elastography in the third trimester - Analysis using a linear mixed effect model

INTRODUCTION

Research into the role of ultrasound elastography to assess compromised placental tissue is ongoing. There is particular interest in evaluating its potential in the investigation of changes associated with uteroplacental dysfunction. To date, there is limited data on how different maternal and fetal considerations, such as advancing gestational age, amniotic fluid Index (AFI) and maternal body mass index (BMI) may influence shear wave velocity (SWV) measurements. This study aimed to evaluate longitudinal changes in SWV throughout gestation and model these changes with other developing fetal and maternal physiological and biological characteristics.

METHODS

The study utilised 238 singleton pregnancies and collected longitudinal data at repeated intervals in the 3rd trimester representing 629 individual data points. Linear mixed model regression analysis was used to identify significant predictors for SWV.

RESULTS

From a total of ten variables selected for modelling, only gestational age, AFI, BMI, and sample depth were found to be significant predictors of placental SWV, and gestational age and AFI were found to have only a minimal impact on SWV.

DISCUSSION

Sophisticated statistical modelling demonstrates that many of the expected maternal and fetal changes in the 3rd trimester have no or minimal impact on placental SWV. Understanding which factors influence placental SWV is essential to ascertain the technique's utility in managing pregnancies complicated by placental dysfunction in the future.

A decline in planned, but not spontaneous, preterm birth rates in a large Australian tertiary maternity centre during COVID-19 mitigation measures

BACKGROUND

Reports from around the world suggest that rates of preterm birth decreased during COVID-19 lockdown measures.

AIMS

To compare the prevalence of preterm birth and stillbirth rates during COVID-19 restriction measures with infants born at the same maternity centre during the same weeks in 2013-2019.

MATERIALS AND METHODS

Deidentified data were extracted from the Mater Mothers' healthcare records database. This is a supra-regional tertiary perinatal centre. Logistic regressions were used to examine singleton live preterm birth rates during the beginning of COVID-19 restrictions (16 March-17 April; 'early'; 6955 births) and during the strictest part of COVID-19 restrictions (30 March-1 May; 'late'; 6953 births), according to gestational age subgroups and birth onset (planned or spontaneous). We adjusted for multiple covariates, including maternal age, body mass index, ethnicity, parity, socioeconomic status, maternal asthma, diabetes mellitus and/or hypertensive disorder. Singleton stillbirth rates were also examined between 16 March-1 May.

RESULTS

Planned moderate/late preterm births declined by more than half during early COVID-19 restrictions compared with the previous seven years (29 vs an average of 64 per 1000 births; adjusted odds ratio 0.39, 95% CI 0.22-0.71). There was no effect on extremely or very preterm infants, spontaneous preterm births, or stillbirth rates. Rolling averages from January to June revealed a two-week non-significant spike in spontaneous preterm births from late April to early May, 2020.

CONCLUSIONS

Together with evidence from other nations, the pandemic provides a unique opportunity to identify causal and preventative factors for preterm birth.

The AGE receptor, OST48 drives podocyte foot process effacement and basement membrane expansion (alters structural composition)

AIMS

The accumulation of advanced glycation end products is implicated in the development and progression of diabetic kidney disease. No study has examined whether stimulating advanced glycation clearance via receptor manipulation is reno-protective in diabetes. Podocytes, which are early contributors to diabetic kidney disease and could be a target for reno-protection.

MATERIALS AND METHODS

To examine the effects of increased podocyte oligosaccharyltransferase-48 on kidney function, glomerular sclerosis, tubulointerstitial fibrosis and proteome (PXD011434), we generated a mouse with increased oligosaccharyltransferase-48kDa subunit abundance in podocytes driven by the podocin promoter.

RESULTS

Despite increased urinary clearance of advanced glycation end products, we observed a decline in renal function, significant glomerular damage including glomerulosclerosis, collagen IV deposition, glomerular basement membrane thickening and foot process effacement and tubulointerstitial fibrosis. Analysis of isolated glomeruli identified enrichment in proteins associated with collagen deposition, endoplasmic reticulum stress and oxidative stress. Ultra-resolution microscopy of podocytes revealed denudation of foot processes where there was co-localization of oligosaccharyltransferase-48kDa subunit and advanced glycation end-products.

CONCLUSIONS

These studies indicate that increased podocyte expression of oligosaccharyltransferase-48 kDa subunit results in glomerular endoplasmic reticulum stress and a decline in kidney function.

Short Duration Alagebrium Chloride Therapy Prediabetes Does Not Inhibit Progression to Autoimmune Diabetes in an Experimental Model

Mechanisms by which advanced glycation end products (AGEs) contribute to type 1 diabetes (T1D) pathogenesis are poorly understood. Since life-long pharmacotherapy with alagebrium chloride (ALT) slows progression to experimental T1D, we hypothesized that acute ALT therapy delivered prediabetes, may be effective. However, in female, non-obese diabetic (NODShiLt) mice, ALT administered prediabetes (day 50-100) did not protect against experimental T1D. ALT did not decrease circulating AGEs or their precursors. Despite this, pancreatic β-cell function was improved, and insulitis and pancreatic CD45.1+ cell infiltration was reduced. Lymphoid tissues were unaffected. ALT pre-treatment, prior to transfer of primed GC98 CD8+ T cell receptor transgenic T cells, reduced blood glucose concentrations and delayed diabetes, suggesting islet effects rather than immune modulation by ALT. Indeed, ALT did not reduce interferon-γ production by leukocytes from ovalbumin-pre-immunised NODShiLt mice and NODscid recipients given diabetogenic ALT treated NOD splenocytes were not protected against T1D. To elucidate β-cell effects, NOD-derived MIN6N8 β-cell major histocompatibility complex (MHC) Class Ia surface antigens were examined using immunopeptidomics. Overall, no major changes in the immunopeptidome were observed during the various treatments with all peptides exhibiting allele specific consensus binding motifs. As expected, longer MHC Class Ia peptides were captured bound to H-2Db than H-2Kb under all conditions. Moreover, more 10-12 mer peptides were isolated from H-2Db after AGE modified bovine serum albumin (AGE-BSA) treatment, compared with bovine serum albumin (BSA) or AGE-BSA+ALT treatment. Proteomics of MIN6N8 cells showed enrichment of processes associated with catabolism, the immune system, cell cycling and presynaptic endocytosis with AGE-BSA compared with BSA treatments. These data show that short-term ALT intervention, given prediabetes, does not arrest experimental T1D but transiently impacts β-cell function.

Perinatal exposure to high dietary advanced glycation end products in transgenic NOD8.3 mice leads to pancreatic beta cell dysfunction

The contribution of environmental factors to pancreatic islet damage in type 1 diabetes remains poorly understood. In this study, we crossed mice susceptible to type 1 diabetes, where parental male (CD8+ T cells specific for IGRP206-214; NOD8.3) and female (NOD/ShiLt) mice were randomized to a diet either low or high in AGE content and maintained on this diet throughout pregnancy and lactation. After weaning, NOD8.3+ female offspring were identified and maintained on the same parental feeding regimen for until day 28 of life. A low AGE diet, from conception to early postnatal life, decreased circulating AGE concentrations in the female offspring when compared to a high AGE diet. Insulin, proinsulin and glucagon secretion were greater in islets isolated from offspring in the low AGE diet group, which was akin to age matched non-diabetic C57BL/6 mice. Pancreatic islet expression of Ins2 gene was also higher in offspring from the low AGE diet group. Islet expression of glucagon, AGEs and the AGE receptor RAGE, were each reduced in low AGE fed offspring. Islet immune cell infiltration was also decreased in offspring exposed to a low AGE diet. Within pancreatic lymph nodes and spleen, the proportions of CD4+ and CD8+ T cells did not differ between groups. There were no significant changes in body weight, fasting glucose or glycemic hormones. This study demonstrates that reducing exposure to dietary AGEs throughout gestation, lactation and early postnatal life may benefit pancreatic islet secretion and immune infiltration in the type 1 diabetic susceptible mouse strain, NOD8.3.

Targeted mitochondrial therapy using MitoQ shows equivalent renoprotection to angiotensin converting enzyme inhibition but no combined synergy in diabetes

Mitochondrial dysfunction is a pathological mediator of diabetic kidney disease (DKD). Our objective was to test the mitochondrially targeted agent, MitoQ, alone and in combination with first line therapy for DKD. Intervention therapies (i) vehicle (D); (ii) MitoQ (DMitoQ;0.6 mg/kg/day); (iii) Ramipril (DRam;3 mg/kg/day) or (iv) combination (DCoAd) were administered to male diabetic db/db mice for 12 weeks (n = 11–13/group). Non-diabetic (C) db/m mice were followed concurrently. No therapy altered glycaemic control or body weight. By the study end, both monotherapies improved renal function, decreasing glomerular hyperfiltration and albuminuria. All therapies prevented tubulointerstitial collagen deposition, but glomerular mesangial expansion was unaffected. Renal cortical concentrations of ATP, ADP, AMP, cAMP, creatinine phosphate and ATP:AMP ratio were increased by diabetes and mostly decreased with therapy. A higher creatine phosphate:ATP ratio in diabetic kidney cortices, suggested a decrease in ATP consumption. Diabetes elevated glucose 6-phosphate, fructose 6-phosphate and oxidised (NAD+ and NADP+) and reduced (NADH) nicotinamide dinucleotides, which therapy decreased generally. Diabetes increased mitochondrial oxygen consumption (OCR) at complex II-IV. MitoQ further increased OCR but decreased ATP, suggesting mitochondrial uncoupling as its mechanism of action. MitoQ showed renoprotection equivalent to ramipril but no synergistic benefits of combining these agents were shown.

The effect of interleukin-22 treatment on autoimmune diabetes in the NOD mouse

AIMS/HYPOTHESIS

The aim of this study was to determine whether therapy with the cytokine IL-22 could be used to prevent the development of, or treat, autoimmune diabetes in the NOD mouse.

METHODS

Six-week-old NOD mice were administered bi-weekly either recombinant mouse IL-22 (200 ng/g) or PBS (vehicle control) intraperitoneally until overt diabetes was diagnosed as two consecutive measurements of non-fasting blood glucose ≥ 11 mmol/l. At this time, NOD mice in the control arm were treated with LinBit insulin pellets and randomised to bi-weekly therapeutic injections of either PBS or IL-22 (200 ng/g) and followed until overt diabetes was diagnosed, as defined above.

RESULTS

IL-22 therapy did not delay the onset of diabetes in comparison with the vehicle-treated mice. We did not observe an improvement in islet area, glycaemic control, beta cell residual function, endoplasmic reticulum stress, insulitis or macrophage and neutrophil infiltration as determined by non-fasting blood glucose, C-peptide and histological scoring. Therapeutic administration of IL-22 did not reduce circulating lipopolysaccharide, a marker of impaired gut mucosal integrity.

CONCLUSIONS/INTERPRETATION

Our study suggests that, at this dosing regimen introduced either prior to overt diabetes or at diagnosis of diabetes, recombinant mouse IL-22 therapy cannot prevent autoimmune diabetes, or prolong the honeymoon period in the NOD mouse.

Receptor for Advanced Glycation End Products (RAGE) in Type 1 Diabetes Pathogenesis

The receptor for advanced glycation end products (RAGE) is a novel protein increasingly studied in the pathogenesis of type 1 diabetes (T1D). RAGE is expressed by several immune cell types, including T cells, antigen-presenting cells, endothelial cells, and the endocrine cells of the pancreatic islets. RAGE binds various ligands including advanced glycation end products (AGEs), high-mobility group box protein 1 (HMGB1), S100 proteins, β-amyloid, β-sheet fibrils, and lipopolysaccharide. AGEs are a particularly interesting ligand because their exogenous introduction into the body can be accelerated by the consumption of AGE-rich processed foods. This review will detail RAGE isoforms and its ligands and discuss how RAGE binding on the aforementioned cells could be linked to T1D pathogenesis.

Antigen-encoding bone marrow terminates islet-directed memory CD8+ T-cell responses to alleviate islet transplant rejection

Islet-specific memory T cells arise early in type 1 diabetes (T1D), persist for long periods, perpetuate disease and are rapidly reactivated by islet transplantation. As memory T cells are poorly controlled by 'conventional' therapies, memory T-cell mediated attack is a substantial challenge in islet transplantation and this will extend to application of personalized approaches using stem-cell derived replacement β cells. New approaches are required to limit memory autoimmune attack of transplanted islets or replacement β cells. Here we show that transfer of bone marrow encoding cognate antigen directed to dendritic cells, under mild, immune-preserving conditions inactivates established memory CD8⁺ T-cell populations and generates a long-lived, antigen-specific tolerogenic environment. Consequently, CD8⁺ memory T cell-mediated targeting of islet-expressed antigens is prevented and islet graft rejection alleviated. The immunological mechanisms of protection are mediated through deletion and induction of unresponsiveness in targeted memory T-cell populations. The data demonstrate that hematopoietic stem cell-mediated gene therapy effectively terminates antigen-specific memory T-cell responses and this can alleviate destruction of antigen-expressing islets. This addresses a key challenge facing islet transplantation and importantly, the clinical application of personalized β-cell replacement therapies using patient-derived stem cells.

Decrease in circulating concentrations of soluble receptors for advanced glycation end products at the time of seroconversion to autoantibody positivity in children with prediabetes

OBJECTIVE

Dietary advanced glycation end products (AGEs) and their interactions with the receptor for AGEs (RAGE) may play a role in the pathogenesis of type 1 diabetes. This study set out to assess whether there is any association of circulating concentrations of soluble RAGE (sRAGE), AGEs, and their ratio with the appearance of diabetes-associated autoantibodies in children progressing to clinical diabetes.

RESEARCH DESIGN AND METHODS

Serum concentrations of sRAGE, N-ε(carboxymethyl)lysine (CML) adducts, and the sRAGE/CML ratio were analyzed in children who progressed to type 1 diabetes. The samples were taken at four time points: before seroconversion, at the time of the first autoantibody-positive sample, at the time of the first sample positive for multiple (>2) autoantibodies, and close to the disease diagnosis. Samples of autoantibody-negative controls matched for age, sex, and HLA-conferred diabetes risk were analyzed at corresponding time points.

RESULTS

The prediabetic children had higher sRAGE concentrations before seroconversion (Pc = 0.03), at the appearance of multiple autoantibodies (Pc = 0.008), and close to diagnosis (Pc = 0.04). Close to diagnosis, the cases had lower CML concentrations than the controls (Pc = 0.004). Prediabetic children had a higher sRAGE/CML ratio than the controls before seroconversion (Pc = 0.008) and at diagnosis (Pc < 0.001).

CONCLUSIONS

Prediabetic children have higher concentrations of sRAGE and a higher sRAGE/CML ratio than healthy controls. Circulating sRAGE concentrations seem to decline with the appearance of diabetes-predictive autoantibodies in children progressing to type 1 diabetes. The higher sRAGE/CML ratio in prediabetic children may reflect a higher AGE scavenger capacity.

Glycemic control in diabetes is restored by therapeutic manipulation of cytokines that regulate beta cell stress

In type 2 diabetes, hyperglycemia is present when an increased demand for insulin, typically due to insulin resistance, is not met as a result of progressive pancreatic beta cell dysfunction. This defect in beta cell activity is typically characterized by impaired insulin biosynthesis and secretion, usually accompanied by oxidative and endoplasmic reticulum (ER) stress. We demonstrate that multiple inflammatory cytokines elevated in diabetic pancreatic islets induce beta cell oxidative and ER stress, with interleukin-23 (IL-23), IL-24 and IL-33 being the most potent. Conversely, we show that islet-endogenous and exogenous IL-22, by regulating oxidative stress pathways, suppresses oxidative and ER stress caused by cytokines or glucolipotoxicity in mouse and human beta cells. In obese mice, antibody neutralization of IL-23 or IL-24 partially reduced beta cell ER stress and improved glucose tolerance, whereas IL-22 administration modulated oxidative stress regulatory genes in islets, suppressed ER stress and inflammation, promoted secretion of high-quality efficacious insulin and fully restored glucose homeostasis followed by restitution of insulin sensitivity. Thus, therapeutic manipulation of immune regulators of beta cell stress reverses the hyperglycemia central to diabetes pathology.

Deletion of bone-marrow-derived receptor for AGEs (RAGE) improves renal function in an experimental mouse model of diabetes

AIMS/HYPOTHESIS

The AGEs and the receptor for AGEs (RAGE) are known contributors to diabetic complications. RAGE also has a physiological role in innate and adaptive immunity and is expressed on immune cells. The aim of this study was to determine whether deletion of RAGE from bone-marrow-derived cells influences the pathogenesis of experimental diabetic nephropathy.

METHODS

Groups (n = 8/group) of lethally irradiated 8 week old wild-type (WT) mice were reconstituted with bone marrow from WT (WT → WT) or RAGE-deficient (RG) mice (RG → WT). Diabetes was induced using multiple low doses of streptozotocin after 8 weeks of bone marrow reconstitution and mice were followed for a further 24 weeks.

RESULTS

Compared with diabetic WT mice reconstituted with WT bone marrow, diabetic WT mice reconstituted with RG bone marrow had lower urinary albumin excretion and podocyte loss, more normal creatinine clearance and less tubulo-interstitial injury and fibrosis. However, glomerular collagen IV deposition, glomerulosclerosis and cortical levels of TGF-β were not different among diabetic mouse groups. The renal tubulo-interstitium of diabetic RG → WT mice also contained fewer infiltrating CD68(+) macrophages that were activated. Diabetic RG → WT mice had lower renal cortical concentrations of CC chemokine ligand 2 (CCL2), macrophage inhibitory factor (MIF) and IL-6 than diabetic WT → WT mice. Renal cortical RAGE ligands S100 calgranulin (S100A)8/9 and AGEs, but not high mobility box protein B-1 (HMGB-1) were also decreased in diabetic RG → WT compared with diabetic WT → WT mice. In vitro, bone-marrow-derived macrophages from WT but not RG mice stimulated collagen IV production in cultured proximal tubule cells.

CONCLUSIONS/INTERPRETATION

These studies suggest that RAGE expression on haemopoietically derived immune cells contributes to the functional changes seen in diabetic nephropathy by promoting macrophage infiltration and renal tubulo-interstitial damage.

Mesenchymal stromal cells improve transplanted islet survival and islet function in a syngeneic mouse model

AIMS/HYPOTHESIS

Islet transplantation is used therapeutically in a minority of patients with type 1 diabetes. Successful outcomes are hampered by early islet beta cell loss. The adjuvant co-transplantation of mesenchymal stromal cells (MSCs) has the promise to improve islet transplant outcome.

METHODS

We used a syngeneic marginal islet mass transplantation model in a mouse model of diabetes. Mice received islets or islets plus 250,000 MSCs. Kidney subcapsule, intra-hepatic and intra-ocular islet transplantation sites were used. Apoptosis, vascularisation, beta cell proliferation, MSC differentiation and laminin levels were determined by immunohistochemical analysis and image quantification post-transplant.

RESULTS

Glucose homeostasis after the transplantation of syngeneic islets was improved by the co-transplantation of MSCs together with islets under the kidney capsule (p = 0.01) and by intravenous infusion of MSCs after intra-hepatic islet transplantation (p = 0.05). MSC co-transplantation resulted in reduced islet apoptosis, with reduced numbers of islet cells positive for cleaved caspase 3 being observed 14 days post-transplant. In kidney subcapsule, but not in intra-ocular islet transplant models, we observed increased re-vascularisation rates, but not increased blood vessel density in and around islets co-transplanted with MSCs compared with islets that were transplanted alone. Co-transplantation of MSCs did not increase beta cell proliferation, extracellular matrix protein laminin production or alpha cell numbers, and there was negligible MSC transdifferentiation into beta cells.

CONCLUSIONS/INTERPRETATION

Co-transplantation of MSCs may lead to improved islet function and survival in the early post-transplantation period in humans receiving islet transplantation.

The use of biomaterials in islet transplantation

Pancreatic islet transplantation is a therapeutic option to replace destroyed β cells in autoimmune diabetes. Islets are transplanted into the liver via the portal vein; however, inflammation, the required immunosuppression, and lack of vasculature decrease early islet viability and function. Therefore, the use of accessory therapy and biomaterials to protect islets and improve islet function has definite therapeutic potential. Here we review the application of niche accessory cells and factors, as well as the use of biomaterials as carriers or capsules, for pancreatic islet transplantation.