editorial the endocrine role of the skeletondownloads.hindawi.com/journals/ije/2015/265151.pdf ·...

EditorialThe Endocrine Role of the Skeleton

Martina Rauner,1 Amélie Coudert,2 Cristina Sobacchi,3,4 and Andrea Del Fattore5

1Medical Faculty of the Technische Universitat Dresden, 01309 Dresden, Germany2Institut National de la Sante et de la Recherche Medicale U1138, Centre de Recherche des Cordeliers, 75006 Paris, France3UOS/IRGB, Milan Unit, National Research Council (CNR), 20138 Milan, Italy4Humanitas Clinical and Research Center, 20089 Rozzano, Italy5Bambino Gesu Children’s Hospital, 00146 Rome, Italy

Correspondence should be addressed to Andrea Del Fattore; [email protected]

Received 28 December 2014; Accepted 28 December 2014

Copyright © 2015 Martina Rauner et al.This is an open access article distributed under the Creative CommonsAttribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In recent years, many advances have been made in theunderstanding of the role of the skeleton in whole bodypathophysiology.

The original vision of the bone as a static tissue withlimited functions is now completely abolished. Indeed itis now well established that bone is a dynamic connectivetissue subjected to a continuous process of resorption andformation. This activity is crucial, since correct bone home-ostasis, skeleton integrity, and mechanical properties relyon a perfect coupling between osteoclasts and osteoblastsfunctions. Indeed recent studies demonstrated that the boneremodelling process is an important regulator of manyfunctions not only limited to the bone, but also correlatedwith the whole body physiology.

In this special issue, experts in the bone field addressedthe interplay between bone and energy metabolism, immunesystem, male fertility, and kidney and documented how bonehas emerged as an endocrine “gland.”

In particular, osteocalcin is indicated as a key factormediating the endocrine functions of bone, with specialfocus on glucose metabolism and male fertility. J. Shao etal. described how osteocalcin targets 𝛽-cells in the pancreasand adipocytes to regulate insulin production and sensitivityand Leydig cells to control testicular function. Moreoverthe authors reviewed the mechanisms regulating osteocalcinproduction and activation, with particular attention to 1𝛼,25-dihydroxyvitamin D3 and vitamin K, and reported studiesin humans supporting the relevance of osteocalcin in energymetabolism and highlighting differences between men and

mice as well as aspects requiring further investigation. M.F. Faienza et al. analyzed the bone-pancreas loop, focusingthe attention not only on osteocalcin, but also on other pro-teins, such as osteoprotegerin, vitamin D, gastric inhibitorypolypeptide (GIP), and adiponectin, involved in the regu-lation of insulin function and glucose metabolism. Antire-sorptive drugs might impact the bone-pancreas interplay;however conflicting results exist on this aspect and deservefurther efforts from the scientific community. In particular,the development of new drugs simultaneously targeting theskeleton, glucose metabolism, and the adipose tissue can beenvisaged. Besides the effects of bone osteocalcin on malefertility, the endocrine role of oestrogens on human maleskeleton was also discussed in this special issue in the paperby V. Rochira et al. The authors described the effects exertedby oestrogens in the physiological events occurring in malebone throughout life such as longitudinal skeletal growth,skeletal proportion, achievement of peak bone mass, andmaintenance of bone mineral density. Moreover the authorsdiscussed clinical aspects of oestrogen deficiency.

In separate chapters, the interplay between bone andkidney is presented. Y. Takei et al. described how bone home-ostasis is finely regulated by a complex mechanism includingFGFs (fibroblast growth factors)/FGF receptors signalling.In particular they emphasized how FGF23, expressed byosteocytes/osteoblasts, reduces the levels of serum phosphateand 1,25(OH)

2D3and the relevance of its coreceptor𝛼Klotho,

produced by kidney distal tubular cells, in the physio-logic regulation of mineral metabolism. In a clinical study

Hindawi Publishing CorporationInternational Journal of EndocrinologyVolume 2015, Article ID 265151, 2 pageshttp://dx.doi.org/10.1155/2015/265151

2 International Journal of Endocrinology

S. Rotondi et al. investigatedwhether a soluble formofKlothocould represent a marker of renal damage of CKD- (chronickidney disease-) MBD (mineral bone disorder), indicativeof the cross-talk between bone and kidney, and concludedthat soluble Klotho could be considered an early marker ofmineral metabolism impairment in renal disease.

Finally, bone diseases, such as osteopetrosis and osteo-porosis, are revisited with the special focus on their relevancefor the endocrine role of the skeleton and on the relationshipwith other diseases, respectively. Indeed, A. E. Coudert et al.described how osteoclast dysfunctions lead to osteopetrosisand have allowed shedding some lights on several aspects ofthe bone biology that were not well known, discovering theinteraction between bone and stomach, insulin metabolism,male fertility, immune system, bone marrow, and fat.

Regarding osteoporosis studies, P. Jackuliak and J. Payeranalyzed the osteoporosis risk in diabetic patients. Moreoverthe authors made clinical considerations and discussed theuse of bone mineral density and the trabecular bone score tostudy different bone properties, quantity and quality, respec-tively. M. Bolanowski et al. investigated how many hormonaldisorders such as Cushing’s syndrome, hyperprolactinemia,acromegaly, hypogonadism, and hypopituitarism influencebone metabolism and can result in secondary osteoporosis.

This special issue should be of interest for basic andclinical researchers since it covers a wide range of topicsregarding bone research. Original studies and reviews havebeen published with the aim to report and summarize thelatest findings regarding the relevance of the skeleton in thewhole body physiology.

Acknowledgment

We are very grateful to all the authors, who submitted papersfor this issue and contributed with their excellent work topublish this successful special issue.

Martina RaunerAmelie Coudert

Cristina SobacchiAndrea Del Fattore

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