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1.
J Intern Med ; 283(2): 121-139, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29211319

RESUMO

Marrow adipocytes, collectively termed marrow adipose tissue (MAT), reside in the bone marrow in close contact to bone cells and haematopoietic cells. Marrow adipocytes arise from the mesenchymal stem cell and share their origin with the osteoblast. Shifts in the lineage allocation of the mesenchymal stromal cell could potentially explain the association between increased MAT and increased fracture risk in diseases such as postmenopausal osteoporosis, anorexia nervosa and diabetes. Functionally, marrow adipocytes secrete adipokines, such as adiponectin, and cytokines, such as RANK ligand and stem cell factor. These mediators can influence both bone remodelling and haematopoiesis by promoting bone resorption and haematopoietic recovery following chemotherapy. In addition, marrow adipocytes can secrete free fatty acids, acting as a energy supply for bone and haematopoietic cells. However, this induced lipolysis is also used by neoplastic cells to promote survival and proliferation. Therefore, MAT could represent a new therapeutic target for multiple diseases from osteoporosis to leukaemia, although the exact characteristics and role of the marrow adipocyte in health and diseases remain to be determined.


Assuntos
Adipócitos/fisiologia , Adiposidade/fisiologia , Medula Óssea/fisiologia , Adipócitos/metabolismo , Envelhecimento/fisiologia , Animais , Anorexia Nervosa/fisiopatologia , Medula Óssea/metabolismo , Crescimento/fisiologia , Humanos , Menopausa/fisiologia , Neoplasias/fisiopatologia , Obesidade/fisiopatologia , Osteoporose/fisiopatologia
2.
Endocrinology ; 157(12): 4930-4942, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27911148

RESUMO

Estrogen deficiency after ovariectomy (OVX) results in increased adiposity and bone loss, which can be prevented by systemic 17-ß estradiol (E2) replacement. Studies in transgenic mice suggested that in addition to direct actions of estrogen in peripheral tissues, also estrogen signaling in the hypothalamus regulates fat distribution and bone metabolism. We hypothesized that the protective effect of systemic E2 on fat and bone metabolism in the OVX model is partly mediated through the ventromedial nucleus of the hypothalamus (VMH). To test this hypothesis, we determined the effect of systemic, central, and targeted VMH administration of E2 on fat and bone metabolism in OVX rats. Subcutaneous administration of E2 for 4 weeks decreased body weight, gonadal and perirenal fat, and bone formation rate in OVX rats. This effect was completely mimicked by intracerebroventricular injections of E2, once every 4 days for 4 weeks. Administration of E2 locally in the VMH by retromicrodialysis (3 h) acutely increased expression of the lipolytic gene hormone-sensitive lipase in gonadal and perirenal fat. Finally, chronic administration of E2 in the VMH for 8 weeks decreased perirenal fat but did not affect body weight, trabecular bone volume, or cortical thickness. In conclusion, we demonstrated that intracerebroventricular E2 replacement reduces body weight gain, ameliorates intraabdominal fat accumulation, and reduces bone formation in the OVX rats. E2 administration selectively in the VMH also reduced intraabdominal fat but did not affect bone metabolism.


Assuntos
Tecido Adiposo/efeitos dos fármacos , Estradiol/administração & dosagem , Fêmur/efeitos dos fármacos , Metabolismo dos Lipídeos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Núcleo Hipotalâmico Ventromedial/efeitos dos fármacos , Tecido Adiposo/metabolismo , Animais , Peso Corporal/efeitos dos fármacos , Feminino , Fêmur/metabolismo , Ovariectomia , Ratos , Esterol Esterase/genética , Esterol Esterase/metabolismo
3.
Bone ; 71: 196-200, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25451321

RESUMO

PURPOSE: Genetic knockout or pharmacological inhibition of the beta-2 adrenergic receptor (B2AR) increased bone mass, whereas stimulation decreased bone mass in rodents. In humans, observational studies support sympathetic nervous system regulation of bone metabolism, but intervention studies are lacking. We aimed to determine the effects of a selective beta-2 adrenergic agonist and non-selective antagonist on human bone metabolism. METHODS: 32 healthy postmenopausal women were included in a randomized controlled trial conducted in the Academic Medical Center Amsterdam. Participants were randomized to receive treatment with 17-ß estradiol 2mg/day; 17-ß estradiol 2mg/day and terbutaline 5mg/day (selective B2AR agonist); propranolol 80mg/day (non-selective B-AR antagonist); or no treatment during 12weeks. Main outcome measure was the change in serum concentrations of procollagen type I N propeptide (P1NP) and C-terminal crosslinking telopeptides of collagen type I (CTx) as markers of bone formation and resorption after 12weeks compared between the treatment groups. Data were analyzed with mixed model analysis. RESULTS: 17-ß estradiol decreased bone turnover compared to control (P1NP p<0.001, CTx p=0.003), but terbutaline combined with 17-ß estradiol failed to increase bone turnover compared to 17-ß estradiol alone (P1NP p=0.135, CTx p=0.406). Propranolol did not affect bone turnover compared to control (P1NP p=0.709, CTx p=0.981). CONCLUSION: Selective beta-2 adrenergic agonists and non-selective beta-antagonists do not affect human bone turnover although we cannot exclude small changes below the detection limit of this study.


Assuntos
Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/metabolismo , Biomarcadores/metabolismo , Remodelação Óssea/efeitos dos fármacos , Colágeno Tipo I/metabolismo , Feminino , Humanos , Pessoa de Meia-Idade , Osteocalcina/metabolismo , Fragmentos de Peptídeos/metabolismo , Peptídeos/metabolismo , Pró-Colágeno/metabolismo
4.
J Clin Endocrinol Metab ; 97(11): E2093-7, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22990094

RESUMO

CONTEXT: The sympathetic nervous system (SNS) controls bone turnover in rodents, but it is uncertain whether a similar role for the SNS exists in humans. Pheochromocytomas are catecholamine-producing neuroendocrine tumors. Because catecholamines are the neurotransmitters of the SNS, we hypothesized that pheochromocytoma patients have increased bone turnover. OBJECTIVE: Our objective was to compare bone turnover in pheochromocytoma patients and controls. DESIGN AND SETTING: This retrospective case-control study was performed at the Endocrine Department of the Academic Medical Center of the University of Amsterdam in The Netherlands from 2007 until 2011. PATIENTS: All patients were screened for pheochromocytoma. Cases (n = 21) were identified by 24-h urinary excretion of fractionated metanephrines above the institutional reference value and confirmed by histology after adrenalectomy. All patients screened and diagnosed as not having pheochromocytoma served as controls (n = 126). MAIN OUTCOME MEASURE: The difference in bone turnover markers C-terminal cross-linking telopeptides of collagen type I (CTx) and procollagen type 1 N propeptide (P1NP) between cases and controls was the main outcome measure. RESULTS: CTx concentrations were higher in cases [343 ng/liter; interquartile range (IQR), 295 ng/liter] than in controls (232 ng/liter; IQR, 168 ng/liter; P < 0.001) and decreased after adrenalectomy [before, 365 ng/liter (IQR, 450 ng/liter); after, 290 ng/liter (IQR, 241 ng/liter); P = 0.044]. The effect remained after adjustment for possible confounders. P1NP concentrations did not differ. CONCLUSIONS: This study shows that pheochromocytoma patients have increased bone resorption, which normalizes after adrenalectomy. This finding supports the concept of regulation of bone remodeling by the SNS in humans.


Assuntos
Neoplasias das Glândulas Suprarrenais/fisiopatologia , Reabsorção Óssea/fisiopatologia , Feocromocitoma/fisiopatologia , Sistema Nervoso Simpático/fisiopatologia , Neoplasias das Glândulas Suprarrenais/cirurgia , Adrenalectomia , Adulto , Idoso , Reabsorção Óssea/cirurgia , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Feocromocitoma/cirurgia , Estudos Retrospectivos , Resultado do Tratamento
5.
Kidney Int ; 71(10): 1001-8, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17361115

RESUMO

Dendritic cells (DCs) play critical roles in immune responses and can be distinguished in two major subsets, myeloid and plasmacytoid DCs. Although the presence of DC in all peripheral organs, including the kidney, has been well documented, no accurate estimates of DC subsets in human kidneys have been reported. This study shows a detailed analysis of DC subsets in cryosections of human renal tissue. The cortex of normal kidneys contains at least two different HLA-DR(+) myeloid DC subtypes characterized by BDCA-1(+)DC-SIGN(+) and BDCA-1(+)DC-SIGN(-). The staining for DC-SIGN completely overlapped with CD68 in the renal interstitium. Unexpectedly, BDCA-2(+)DC-SIGN(-) plasmacytoid DCs are also abundantly present. Both subsets are located in the tubulo-interstitium often with a high frequency around, but rarely observed within glomeruli. Quantification of BDCA-1(+), DC-SIGN(+), and BDCA-2(+) cells in normal human renal tissue (pretransplant biopsy living donors; n=21) revealed that BDCA-1 is about four times as frequently present as BDCA-2. A preliminary cross-sectional analysis of DC in diseased kidneys, including rejection and immunoglobulin A nephropathy, revealed that the number of DC as well as their anatomical distribution might change under pathophysiological conditions. In conclusion, we show that human kidneys contain a dense network of myeloid and plasmacytoid DCs and provide the tools for phenotyping and enumeration of these cells to better understand interindividual differences in immune responses.


Assuntos
Células Dendríticas/classificação , Nefropatias/patologia , Rim/citologia , Rim/patologia , Adulto , Antígenos CD1 , Antígenos de Superfície/metabolismo , Moléculas de Adesão Celular/deficiência , Moléculas de Adesão Celular/metabolismo , Estudos Transversais , Células Dendríticas/citologia , Células Dendríticas/metabolismo , Células Dendríticas/patologia , Imunofluorescência , Glicoproteínas , Humanos , Imuno-Histoquímica/métodos , Transplante de Rim , Lectinas Tipo C/deficiência , Lectinas Tipo C/metabolismo , Doadores Vivos , Glicoproteínas de Membrana/deficiência , Glicoproteínas de Membrana/metabolismo , Pessoa de Meia-Idade , Células Mieloides/citologia , Plasmócitos/citologia , Receptores de Superfície Celular/deficiência , Receptores de Superfície Celular/metabolismo , Receptores Imunológicos/deficiência , Receptores Imunológicos/metabolismo , Coloração e Rotulagem
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