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Magodoro IM, Aluoch A, Claggett B, Nyirenda MJ, Siedner MJ, Wilkinson KA, Wilkinson RJ, Ntusi N. Insulin resistance, and not β-cell impairment, mediates association between Mycobacterium tuberculosis sensitization and type II diabetes mellitus among US adults. medRxiv 2024:2024.03.10.24304039. [PMID: 38559227 PMCID: PMC10980119 DOI: 10.1101/2024.03.10.24304039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Type 2 diabetes mellitus (T2DM) may be a long-term sequela of infection with Mycobacterium tuberculosis (M.tb) by mechanisms that remain to be fully explained. We evaluated association between M.tb sensitization and T2DM among U.S adults and, via formal mediation analysis, the extent to which this association is mediated by insulin resistance and/or β-cell failure. These evaluations accounted for demographic, socio-economic, behavioral and clinical characteristics. T2DM was assessed by fasting plasma glucose, 2-hour oral glucose tolerance testing and HbA1c; homoeostasis model assessment 2 (HOMA2) was used to estimate β-cell dysfunction (HOMA2-B) and insulin resistance (HOMA2-IR); while M.tb sensitization status was ascertained by tuberculin skin testing (TST). Exposure to M.tb was associated with increased risk for T2DM, likely driven by an increase in insulin resistance. Definitive prospective studies examining incident T2DM following tuberculosis are warranted. Research in Context What is already known about this subject?: Accumulating evidence suggests that pre-diabetes and new-onset type 2 diabetes mellitus (T2DM) may be a long-term complication of exposure to Mycobacterium tuberculosis ( M.tb ) via mechanisms that remain to be unraveled What is the key question?: To what extent do insulin resistance and β-cell failure mediate the association between M.tb sensitization with T2DM among US adults? What are the new findings?: M.tb sensitization is characterized by distinct glucose metabolic disturbances manifesting as increased risk of T2DM and isolated impaired fasting glucose (IFG) Insulin resistance, and not β-cell impairment, likely independently mediate the observed diabetogenic effects of M.tb sensitization How might this impact on clinical and/or public health practice in the foreseeable future?: If corroborated by prospective studies, both TB programs and individual clinical care must incorporate monitoring of serum glucose and long-term metabolic outcomesThis will be particularly urgent in sub-Saharan Africa and South-East Asia where scarce health resources coincide with overlapping endemic TB and epidemic T2DM.
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Magodoro IM, Castle AC, Tshuma N, Goedecke JH, Sewpaul R, Manasa J, Manne-Goehler J, Ntusi N, Nyirenda MJ, Siedner MJ. Associations of HIV and prevalent type 2 diabetes mellitus in the context of obesity in South Africa. medRxiv 2024:2024.03.10.24304033. [PMID: 38559082 PMCID: PMC10980116 DOI: 10.1101/2024.03.10.24304033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
It is unclear how rising obesity among people with HIV (PWH) in sub-Saharan Africa (SSA) impacts their risk of type 2 diabetes mellitus (diabetes). Using a South African national cross-sectional sample of adult PWH and their peers without HIV (PWOH), we examined the associations between HIV and prevalent diabetes across the spectrum of body mass index (BMI), waist circumference (WC) and waist-to-height ratio (WtHR). Analyses were sex stratified, and adjusted for age, sociodemographic and behavioral factors. The prevalence of diabetes among males was similar between PWH and PWOH, overall and at all levels of adiposity. In contrast, overall diabetes prevalence was higher among female PWOH than female PWH. However, there were differences according to adiposity such that, compared to female PWOH, relative diabetes prevalence in female PWH was reduced with obesity but accentuated with leanness. These differences in the relationship between adiposity and diabetes by HIV serostatus call for better mechanistic understanding of sex-specific adipose tissue biology in HIV in South Africa, and possibly in other HIV endemic settings in SSA.
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Milln JM, Walugembe E, Ssentayi S, Nkabura H, Jones AG, Nyirenda MJ. Comparison of oral glucose tolerance test and ambulatory glycaemic profiles in pregnant women in Uganda with gestational diabetes using the FreeStyle Libre flash glucose monitoring system. BMC Pregnancy Childbirth 2020; 20:635. [PMID: 33076849 PMCID: PMC7574406 DOI: 10.1186/s12884-020-03325-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 10/09/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The diagnosis of hyperglycaemia in sub-Saharan Africa (SSA) is challenging. Blood glucose levels obtained during oral glucose tolerance test (OGTT) may not reflect home glycaemic profiles. We compare OGTT results with home glycaemic profiles obtained using the FreeStyle Libre continuous glucose monitoring device (FSL-CGM). METHODS Twenty-eight women (20 with gestational diabetes [GDM], 8 controls) were recruited following OGTT between 24 and 28 weeks of gestation. All women wore the FSL-CGM device for 48-96 h at home in early third trimester, and recorded a meal diary. OGTT was repeated on the final day of FSL-CGM recording. OGTT results were compared with ambulatory glycaemic variables, and repeat OGTT was undertaken whilst wearing FSL-CGM to determine accuracy of the device. RESULTS FSL-CGM results were available for 27/28 women with mean data capture 92.8%. There were significant differences in the ambulatory fasting, post-prandial peaks, and mean glucose between controls in whom both primary and secondary OGTT was normal (n = 6) and those with two abnormal OGTTs or "true" GDM (n = 7). There was no difference in ambulatory mean glucose between these controls and the 13 women who had an abnormal primary OGTT and normal repeat OGTT. These participants had significantly lower body mass index (BMI) than the true GDM group (29.0 Vs 36.3 kg/m2, p-value 0.014). Paired OGTT/FSL-CGM readings revealed a Mean Absolute difference (MAD) -0.58 mmol/L and Mean Absolute Relative Difference (MARD) -11.9%. Bland-Altman plot suggests FSL-CGM underestimated blood glucose by approximately 0.78 mmol/L. CONCLUSION Diagnosis of GDM on a single OGTT identifies a proportion of women who do not have a significantly higher home glucose levels than controls. This raises questions about factors which may affect the reproducibility of OGTT in this population, including food insecurity and atypical phenotypes of diabetes. More investigation is needed to understand the suitability of the OGTT as a diagnostic test in sub-Saharan Africa.
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Affiliation(s)
- J M Milln
- Non-Communicable Diseases Theme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine (MRC/UVRI & LSHTM) Uganda Research Unit, Plot 51-59, Nakiwogo Road, P. O. BOX 49, Entebbe, Uganda.
- Department of Endocrinology and Diabetes, Queen Mary University of London, Mile End Road, London, UK.
| | - E Walugembe
- Non-Communicable Diseases Theme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine (MRC/UVRI & LSHTM) Uganda Research Unit, Plot 51-59, Nakiwogo Road, P. O. BOX 49, Entebbe, Uganda
| | - S Ssentayi
- Non-Communicable Diseases Theme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine (MRC/UVRI & LSHTM) Uganda Research Unit, Plot 51-59, Nakiwogo Road, P. O. BOX 49, Entebbe, Uganda
| | - H Nkabura
- Non-Communicable Diseases Theme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine (MRC/UVRI & LSHTM) Uganda Research Unit, Plot 51-59, Nakiwogo Road, P. O. BOX 49, Entebbe, Uganda
| | - A G Jones
- National Institute for Health and Research (NIHR), Exeter Clinical Research Facility, University of Exeter Medical School, Exeter, UK
| | - M J Nyirenda
- Non-Communicable Diseases Theme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine (MRC/UVRI & LSHTM) Uganda Research Unit, Plot 51-59, Nakiwogo Road, P. O. BOX 49, Entebbe, Uganda
- Department of Non-Communicable Diseases Epidemiology, London School of Hygiene and Tropical Medicine (LSHTM), London, UK
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Barr AL, Young EH, Smeeth L, Newton R, Seeley J, Ripullone K, Hird TR, Thornton JRM, Nyirenda MJ, Kapiga S, Adebamowo CA, Amoah AG, Wareham N, Rotimi CN, Levitt NS, Ramaiya K, Hennig BJ, Mbanya JC, Tollman S, Motala AA, Kaleebu P, Sandhu MS. The need for an integrated approach for chronic disease research and care in Africa. Glob Health Epidemiol Genom 2016; 1:e19. [PMID: 29868211 PMCID: PMC5870416 DOI: 10.1017/gheg.2016.16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 08/09/2016] [Accepted: 09/11/2016] [Indexed: 02/06/2023] Open
Abstract
With the changing distribution of infectious diseases, and an increase in the burden of non-communicable diseases, low- and middle-income countries, including those in Africa, will need to expand their health care capacities to effectively respond to these epidemiological transitions. The interrelated risk factors for chronic infectious and non-communicable diseases and the need for long-term disease management, argue for combined strategies to understand their underlying causes and to design strategies for effective prevention and long-term care. Through multidisciplinary research and implementation partnerships, we advocate an integrated approach for research and healthcare for chronic diseases in Africa.
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Affiliation(s)
- A. L. Barr
- Department of Medicine, University of Cambridge, Cambridge, UK
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, UK
| | - E. H. Young
- Department of Medicine, University of Cambridge, Cambridge, UK
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, UK
| | - L. Smeeth
- Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - R. Newton
- Medical Research Council/Uganda Virus Research Institute (MRC/UVRI), Uganda Research Unit on AIDS, Entebbe, Uganda
| | - J. Seeley
- Medical Research Council/Uganda Virus Research Institute (MRC/UVRI), Uganda Research Unit on AIDS, Entebbe, Uganda
- Global Health and Development, London School of Hygiene & Tropical Medicine, London, UK
| | - K. Ripullone
- Department of Medicine, University of Cambridge, Cambridge, UK
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, UK
| | - T. R. Hird
- Department of Medicine, University of Cambridge, Cambridge, UK
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, UK
| | - J. R. M. Thornton
- Department of Medicine, University of Cambridge, Cambridge, UK
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, UK
| | - M. J. Nyirenda
- Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK
- Malawi Epidemiology and Intervention Research Unit, Lilongwe, Malawi
| | - S. Kapiga
- Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK
- Mwanza Intervention Trials Unit, National Institute for Medical Research, Mwanza, Tanzania
| | - C. A. Adebamowo
- Department of Epidemiology and Public Health, Greenebaum Comprehensive Cancer Center and Institute of Human Virology, University of Maryland School of Medicine, Baltimore MD 21201 USA
- Institute of Human Virology, Nigeria
| | - A. G. Amoah
- Department of Medicine, University of Ghana Medical School, Korlebu, Ghana
| | - N. Wareham
- MRC Epidemiology Unit, University of Cambridge, Cambridge, UK
| | - C. N. Rotimi
- Center for Research on Genomics and Global Health, National Human Genome Research Institute, National Institutes of Health, Bethesda, USA
| | - N. S. Levitt
- Division of Diabetic Medicine and Endocrinology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - K. Ramaiya
- Shree Hindu Mandal Hospital, Dar es Salaam, Tanzania
| | - B. J. Hennig
- MRC Unit, The Gambia, Fajara, The Gambia
- MRC International Nutrition Group, London School of Hygiene & Tropical Medicine, London, UK
| | - J. C. Mbanya
- Department of Internal Medicine and Specialties, Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon
| | - S. Tollman
- MRC/Wits Rural Public Health and Health Transitions Research Unit, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- INDEPTH Network, Accra, Ghana
| | - A. A. Motala
- Department of Diabetes and Endocrinology, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa
| | - P. Kaleebu
- Medical Research Council/Uganda Virus Research Institute (MRC/UVRI), Uganda Research Unit on AIDS, Entebbe, Uganda
| | - M. S. Sandhu
- Department of Medicine, University of Cambridge, Cambridge, UK
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, UK
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Assayed AA, Muula AS, Nyirenda MJ. The quality of care of diabetic patients in rural Malawi: A case of Mangochi district. Malawi Med J 2014; 26:109-114. [PMID: 26167259 PMCID: PMC4325344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
BACKGROUND Diabetes mellitus is a global public health problem. In Malawi, the prevalence of diabetes is 5.6% but the quality of care has not been well studied. OBJECTIVE The aim of this study was to assess the quality of care offered to diabetic patients in Mangochi district. METHODS This was a cross sectional descriptive study. Quantitative data were collected using a questionnaire from a sample of 75 diabetic patients (children and adults) who attended the Diabetes Clinic at Mangochi District Hospital between 20012 and 2013. Qualitative data were also collected using semi-structured interviews with eight Key Informants from among the District Health Management Team. Frequencies and cross-tabulation were obtained from the quantitative data. Patients' master cards were checked to validate results. Clinical knowledge about diabetes, care practices and resources were the themes analysed from the qualitative data. RESULTS Among the 75 participants interviewed, 46 were females and 29 males. The overall mean age was 48.3 years (45.6 for females and 53.3 for males). More than half of patients had little or no information about diabetes (40.0 % (n=30) and 22.7 (n=17) respectively. The majority of patients were taking their medicines regularly 98.7% (n=74). Only 17.3% (n=13) reported having their feet inspected regularly. Fifty-six percent of patients were satisfied about services provision. Some nurses and clinicians were trained on diabetes care but most of them left. Guidelines on diabetes management were not accessible. There were shortages in medicines (e.g. soluble insulin) and reagents. Information Education and Communication messages were offered through discussions, experiences sharing and posters. CONCLUSION Quality of diabetes care provided to diabetic patients attended to Mangochi hospital was sub-optimal due to lack of knowledge among patients and clinicians and resources. More efforts are needed towards retention of trained staff, provision of pharmaceutical and laboratory resources and health education.
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Affiliation(s)
- A A Assayed
- Albaraka Charity Trust, Mama Kadija Clinic, Mangochi, Malawi
| | - A S Muula
- Department of Community Health, College of Medicine, University of Malawi, Blantyre Malawi
| | - M J Nyirenda
- Department of Medicine, College of Medicine, University of Malawi, Blantyre, Malawi ; Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Nyirenda MJ, Dean S, Lyons V, Chapman KE, Seckl JR. Prenatal programming of hepatocyte nuclear factor 4alpha in the rat: A key mechanism in the 'foetal origins of hyperglycaemia'? Diabetologia 2006; 49:1412-20. [PMID: 16570165 DOI: 10.1007/s00125-006-0188-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2005] [Accepted: 12/02/2005] [Indexed: 11/27/2022]
Abstract
AIMS/HYPOTHESIS Prenatal glucocorticoid exposure causes lifelong hyperglycaemia in rat offspring, associated with permanently increased hepatic phosphoenolpyruvate carboxykinase 2 (PCK2), the rate-controlling enzyme of gluconeogenesis. To elucidate the mechanisms underlying the 'programming' of PCK2, this study examined the effect of prenatal dexamethasone treatment on expression of transcription factors that regulate Pck2. MATERIALS AND METHODS Real-time RT-PCR and in situ hybridisation were used to measure and localise hepatic mRNA transcribed from the genes for PCK2, hepatocyte nuclear factor 4, alpha (HNF4A), transcription factor 1 (TCF1), CCAAT/enhancer binding protein, alpha (CEBPA), CEBPB, the glucocorticoid receptor (NR3C1) and peroxisome proliferative activated receptor, gamma, coactivator 1 alpha (PPARGC1A) in foetal and adult offspring of dams treated with dexamethasone or vehicle during the last week of gestation. RESULTS Prenatal dexamethasone exposure significantly elevated Hnf4a mRNA expression in foetal and adult liver. This resulted from increased expression of isoforms derived from the 'adult' (P1) Hnf4a promoter. In contrast, isoforms from the 'foetal' (P2) promoter were markedly suppressed by dexamethasone. Like Pck2, the increase in hepatic Hnf4a mRNA occurred exclusively in the periportal zone. Foetal Tcf1 expression was also increased by dexamethasone treatment, but this did not persist into adulthood. Prenatal dexamethasone did not affect the amounts of foetal and/or adult Cebpa, Cebpb, Nr3c1 or Ppargc1a mRNA. CONCLUSIONS/INTERPRETATION Prenatal dexamethasone exposure caused a permanent increase in hepatic Hnf4a mRNA. This increase, which was associated with a premature switch from foetal to adult promoter predominance, was congruent with changes in Pck2 expression. These data suggest that HNF4A might mediate Pck2 overexpression and subsequent hyperglycaemia.
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Affiliation(s)
- M J Nyirenda
- Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
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Abstract
BACKGROUND Metformin has been shown to reduce complications and mortality from Type 2 diabetes mellitus, and is increasingly used to treat this condition. This agent is, however, associated with a rare but serious risk of lactic acidosis. CASE REPORT We present cases of 10 patients with Type 2 diabetes mellitus who developed acute renal failure and severe lactic acidosis. Despite the severity of their illness, all patients but one survived. CONCLUSIONS The increasing prevalence of Type 2 diabetes and its treatment with metformin might result in more cases of lactic acidosis. However our case report demonstrates that early and aggressive treatment with haemofiltration can improve outcomes even in the presence of severe acidosis.
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Affiliation(s)
- M J Nyirenda
- Metabolic Unit, Western General Hospital, Edinburgh, UK
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Nyirenda MJ, Dean S, Seckl JR. Prenatal glucocorticoid exposure and physiological programming of adult disease. Exp Clin Endocrinol Diabetes 2005. [DOI: 10.1055/s-2005-920435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
In a previous study, we showed that exposure of rats to dexamethasone (Dex) selectively in late pregnancy produces permanent induction of hepatic phosphoenolpyruvate carboxykinase (PEPCK) expression and hyperglycaemia in the adult offspring. The mechanisms by which glucocorticoids cause this programming are unclear but may involve direct actions on the fetus/neonate, or glucocorticoids may act indirectly by affecting maternal postnatal nursing behaviour. Using a cross-fostering paradigm, the present data demonstrate that switching the offspring at birth from Dex-treated dams to control dams does not prevent induction of PEPCK or hyperglycaemia. Similarly, offspring born to control dams but reared by Dex-treated dams from birth maintain normal glycaemic control. During the neonatal period, injection of saline per se was sufficient to cause exaggeration in adult offspring responses to an oral glucose load, with no additional effect from Dex. However, postnatal treatment with either saline or Dex did not alter hepatic PEPCK activity. Prenatal Dex permanently raised basal plasma corticosterone levels, but under stress conditions there were no differences in circulating corticosterone levels. Likewise, Dex-exposed rats had similar plasma catecholamine concentrations to control animals. These findings show that glucocorticoids programme hyperglycaemia through mechanisms that operate on the fetus or directly on the neonate, rather than via effects that alter maternal postnatal behaviour during the suckling period. The hyperglycaemic response does not appear to result from abnormal sympathoadrenal activity or hypothalamic-pituitary-adrenal response during stress.
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Affiliation(s)
- M J Nyirenda
- Molecular Endocrinology Laboratory, Molecular Medicine Centre, University of Edinburgh, Western General Hospital, Edinburgh, UK.
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Abstract
Epidemiological studies in many distinct human populations have associated low weight or thinness at birth with a substantially increased risk of cardiovascular and metabolic disorders, including hypertension and insulin resistance/type 2 diabetes, in adult life. The concept of fetal "programming" has been advanced to explain this phenomenon. Prenatal glucocorticoid therapy reduces birthweight, and steroids are known to exert long-term organizational effects during specific "windows" of development. Therefore, we hypothesized that fetal overexposure to endogenous glucocorticoids might underpin the link between early life events and later disease. In rats, birthweight is reduced following prenatal exposure to the synthetic glucocorticoid dexamethasone, which readily crosses the placenta, or to carbenoxolone, which inhibits 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), the physiological feto-placental "barrier" to endogenous glucocorticoids. Although the offspring regain the weight deficit by weaning, as adults they exhibit permanent hypertension, hyperglycemia, and increased hypothalamic-pituitary-adrenal axis activity. Moreover, physiological variations in placental 11beta-HSD2 activity near term correlate directly with fetal weight. In humans, 11beta-HSD2 gene mutations produce a low birthweight, and some studies show reduced placental 11beta-HSD2 activity in association with intrauterine growth retardation. Moreover, low birthweight babies have higher plasma cortisol levels throughout adult life, indicating that hypothalamic-pituitary-adrenal axis programming also occurs in humans. The molecular mechanisms of glucocorticoid programming are beginning to be unraveled and involve permanent and tissue-specific changes in the expression of key genes, notably of the glucocorticoid receptor itself. Thus, glucocorticoid programming may explain, in part, the association between fetal events and subsequent disorders in adult life.
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Affiliation(s)
- J R Seckl
- Molecular Medicine Center, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom.
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Affiliation(s)
- J R Seckl
- Molecular Medicine Centre, University of Edinburgh, Western General Hospital, U.K
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Jamieson PM, Nyirenda MJ, Walker BR, Chapman KE, Seckl JR. Interactions between oestradiol and glucocorticoid regulatory effects on liver-specific glucocorticoid-inducible genes: possible evidence for a role of hepatic 11beta-hydroxysteroid dehydrogenase type 1. J Endocrinol 1999; 160:103-9. [PMID: 9854182 DOI: 10.1677/joe.0.1600103] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In vitro, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) catalyses the interconversion of active corticosterone and inert 11-dehydrocorticosterone. 11beta-HSD-1 is highly expressed in liver, where the reaction direction is 11beta-reduction, thus potentially increasing intrahepatic active glucocorticoid levels. Inhibition of 11beta-HSD-1 increases insulin sensitivity in humans in vivo suggesting that hepatic 11beta-HSD-1 plays a role in the maintenance or control of key glucocorticoid-regulated metabolic functions. We have selectively repressed hepatic 11beta-HSD-1 in rats by oestradiol administration for 42 days. This nearly completely repressed hepatic 11beta-HSD-1 mRNA expression and enzyme activity and reduced expression of hepatic glucocorticoid-inducible genes including phosphoenolpyruvate carboxykinase (PEPCK), the rate-limiting step in gluconeogenesis. Similar effects were seen after 3 weeks of oestradiol treatment. To examine whether this was due to any direct effect of oestradiol upon PEPCK, the experiment was repeated in adrenalectomised rats+/-glucocorticoid replacement. In adrenalectomised rats, oestradiol did not attenuate hepatic PEPCK, whilst glucocorticoid replacement restored this action. Oestradiol did not alter hepatic metabolism of corticosterone by pathways other than 11beta-HSD-1. These data suggest 11beta-HSD-1 plays an important role in maintaining expression of key glucocorticoid-regulated hepatic transcripts. Enzyme inhibition may provide a useful therapeutic target for manipulating glucose homeostasis.
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Affiliation(s)
- P M Jamieson
- Molecular Endocrinology, Molecular Medicine Centre, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
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Abstract
There is increasing epidemiological evidence in humans which associates low birth weight with later cardiovascular and metabolic disorders including hypertension, insulin resistance, hyperlipidaemia and death from ischaemic heart disease. The molecular mechanisms underlying this link are unknown but fetal glucocorticoid exposure may play a role. In adult mammals, glucocorticoid hormones are involved in control of several physiological processes that maintain homeostasis including coordination of responses to stress. During development, glucocorticoids have important regulatory functions to prepare the organism for metabolic adaptations necessary for extrauterine life. Fetal glucocorticoid load is, in part, regulated by placental and fetal 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) which catalyses a rapid breakdown of maternal and fetal glucocorticoids into inert products. Supraphysiological doses of glucocorticoids retard fetal growth, and human intrauterine growth retardation is associated with elevated cortisol levels. Recent studies have shown that exposing rats to excessive glucocorticoids in utero reduces birth weight and causes permanent hypertension and hyperglycaemia in the adult offspring. These observations show that glucocorticoids could be the link between low birth weight and later disease. Understanding of the molecular details involved in prenatal glucocorticoid action may provide novel insights into the pathogenesis of common cardiovascular and metabolic disorders.
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Affiliation(s)
- M J Nyirenda
- Molecular Endocrinology Laboratory, Molecular Medicine Centre, University of Edinburgh, Western General Hospital, UK
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Nyirenda MJ, Lindsay RS, Kenyon CJ, Burchell A, Seckl JR. Glucocorticoid exposure in late gestation permanently programs rat hepatic phosphoenolpyruvate carboxykinase and glucocorticoid receptor expression and causes glucose intolerance in adult offspring. J Clin Invest 1998; 101:2174-81. [PMID: 9593773 PMCID: PMC508805 DOI: 10.1172/jci1567] [Citation(s) in RCA: 439] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Low birth weight in humans is predictive of insulin resistance and diabetes in adult life. The molecular mechanisms underlying this link are unknown but fetal exposure to excess glucocorticoids has been implicated. The fetus is normally protected from the higher maternal levels of glucocorticoids by feto-placental 11beta-hydroxysteroid dehydrogenase type-2 (11beta-HSD2) which inactivates glucocorticoids. We have shown previously that inhibiting 11beta-HSD2 throughout pregnancy in rats reduces birth weight and causes hyperglycemia in the adult offspring. We now show that dexamethasone (a poor substrate for 11beta-HSD2) administered to pregnant rats selectively in the last week of pregnancy reduces birth weight by 10% (P < 0.05), and produces adult fasting hyperglycemia (treated 5.3+/-0.3; control 4.3+/-0.2 mmol/ liter, P = 0.04), reactive hyperglycemia (treated 8.7+/-0.4; control 7.5+/-0.2 mmol/liter, P = 0.03), and hyperinsulinemia (treated 6.1+/-0.4; control 3.8+/-0.5 ng/ml, P = 0.01) on oral glucose loading. In the adult offspring of rats exposed to dexamethasone in late pregnancy, hepatic expression of glucocorticoid receptor (GR) mRNA and phosphoenolpyruvate carboxykinase (PEPCK) mRNA (and activity) are increased by 25% (P = 0.01) and 60% (P < 0.01), respectively, while other liver enzymes (glucose-6-phosphatase, glucokinase, and 11beta-hydroxysteroid dehydrogenase type-1) are unaltered. In contrast dexamethasone, when given in the first or second week of gestation, has no effect on offspring insulin/glucose responses or hepatic PEPCK and GR expression. The increased hepatic GR expression may be crucial, since rats exposed to dexamethasone in utero showed potentiated glucose responses to exogenous corticosterone. These observations suggest that excessive glucocorticoid exposure late in pregnancy predisposes the offspring to glucose intolerance in adulthood. Programmed hepatic PEPCK overexpression, perhaps mediated by increased GR, may promote this process by increasing gluconeogenesis.
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Affiliation(s)
- M J Nyirenda
- Molecular Endocrinology Laboratory, Molecular Medicine Centre, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom.
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