Bone and Muscle Endocrine Functions: Unexpected Paradigms of Inter-organ Communication.

Most physiological functions originate with the communication between organs. Mouse genetics has revived this holistic view of physiology through the identification of inter-organ communications that are unanticipated, functionally important, and would have been difficult to uncover otherwise. This Review highlights this point by showing how two tissues usually not seen as endocrine ones, bone and striated muscles, influence several physiological processes in a significant manner.

Maternal and offspring pools of osteocalcin influence brain development and functions.

The powerful regulation of bone mass exerted by the brain suggests the existence of bone-derived signals modulating this regulation or other functions of the brain. We show here that the osteoblast-derived hormone osteocalcin crosses the blood-brain barrier, binds to neurons of the brainstem, midbrain, and hippocampus, enhances the synthesis of monoamine neurotransmitters, inhibits GABA synthesis, prevents anxiety and depression, and favors learning and memory independently of its metabolic functions. In addition to these postnatal functions, maternal osteocalcin crosses the placenta during pregnancy and prevents neuronal apoptosis before embryos synthesize this hormone. As a result, the severity of the neuroanatomical defects and learning and memory deficits of Osteocalcin(-/-) mice is determined by the maternal genotype, and delivering osteocalcin to pregnant Osteocalcin(-/-) mothers rescues these abnormalities in their Osteocalcin(-/-) progeny. This study reveals that the skeleton via osteocalcin influences cognition and contributes to the maternal influence on fetal brain development.

Osteocalcin of maternal and embryonic origins synergize to establish homeostasis in offspring.

Many physiological osteocalcin-regulated functions are affected in adult offspring of mothers experiencing unhealthy pregnancy. Furthermore, osteocalcin signaling during gestation influences cognition and adrenal steroidogenesis in adult mice. Together these observations suggest that osteocalcin may broadly function during pregnancy to determine organismal homeostasis in adult mammals. To test this hypothesis, we analyzed in unchallenged wildtype and Osteocalcin-deficient, newborn and adult mice of various genotypes and origin maintained on different genetic backgrounds, the functions of osteocalcin in the pancreas, liver and testes and their molecular underpinnings. This analysis revealed that providing mothers are Osteocalcin-deficient, Osteocalcin haploinsufficiency in embryos hampers insulin secretion, liver gluconeogenesis, glucose homeostasis, testes steroidogenesis in adult offspring; inhibits cell proliferation in developing pancreatic islets and testes; and disrupts distinct programs of gene expression in these organs and in the brain. This study indicates that osteocalcin exerts dominant functions in most organs it influences. Furthermore, through their synergistic regulation of multiple physiological functions, osteocalcin of maternal and embryonic origins contributes to the establishment and maintenance of organismal homeostasis in newborn and adult offspring.

Endocrine regulation of male fertility by the skeleton.

Interactions between bone and the reproductive system have until now been thought to be limited to the regulation of bone remodeling by the gonads. We now show that, in males, bone acts as a regulator of fertility. Using coculture assays, we demonstrate that osteoblasts are able to induce testosterone production by the testes, though they fail to influence estrogen production by the ovaries. Analyses of cell-specific loss- and gain-of-function models reveal that the osteoblast-derived hormone osteocalcin performs this endocrine function. By binding to a G protein-coupled receptor expressed in the Leydig cells of the testes, osteocalcin regulates in a CREB-dependent manner the expression of enzymes that is required for testosterone synthesis, promoting germ cell survival. This study expands the physiological repertoire of osteocalcin and provides the first evidence that the skeleton is an endocrine regulator of reproduction.

Insulin signaling in osteoblasts integrates bone remodeling and energy metabolism.

The broad expression of the insulin receptor suggests that the spectrum of insulin function has not been fully described. A cell type expressing this receptor is the osteoblast, a bone-specific cell favoring glucose metabolism through a hormone, osteocalcin, that becomes active once uncarboxylated. We show here that insulin signaling in osteoblasts is necessary for whole-body glucose homeostasis because it increases osteocalcin activity. To achieve this function insulin signaling in osteoblasts takes advantage of the regulation of osteoclastic bone resorption exerted by osteoblasts. Indeed, since bone resorption occurs at a pH acidic enough to decarboxylate proteins, osteoclasts determine the carboxylation status and function of osteocalcin. Accordingly, increasing or decreasing insulin signaling in osteoblasts promotes or hampers glucose metabolism in a bone resorption-dependent manner in mice and humans. Hence, in a feed-forward loop, insulin signals in osteoblasts activate a hormone, osteocalcin, that promotes glucose metabolism.

Insulin receptor signaling in osteoblasts regulates postnatal bone acquisition and body composition.

Global energy balance in mammals is controlled by the actions of circulating hormones that coordinate fuel production and utilization in metabolically active tissues. Bone-derived osteocalcin, in its undercarboxylated, hormonal form, regulates fat deposition and is a potent insulin secretagogue. Here, we show that insulin receptor (IR) signaling in osteoblasts controls osteoblast development and osteocalcin expression by suppressing the Runx2 inhibitor Twist2. Mice lacking IR in osteoblasts have low circulating undercarboxylated osteocalcin and reduced bone acquisition due to decreased bone formation and deficient numbers of osteoblasts. With age, these mice develop marked peripheral adiposity and hyperglycemia accompanied by severe glucose intolerance and insulin resistance. The metabolic abnormalities in these mice are improved by infusion of undercarboxylated osteocalcin. These results indicate the existence of a bone-pancreas endocrine loop through which insulin signaling in the osteoblast ensures osteoblast differentiation and stimulates osteocalcin production, which in turn regulates insulin sensitivity and pancreatic insulin secretion.

High glucose promotes osteogenic differentiation of human lens epithelial cells through hypoxia-inducible factor (HIF) activation.

Cataract, a leading cause of blindness, is characterised by lens opacification. Type 2 diabetes is associated with a two- to fivefold higher prevalence of cataracts. The risk of cataract formation increases with the duration of diabetes and the severity of hyperglycaemia. Hydroxyapatite deposition is present in cataractous lenses that could be the consequence of osteogenic differentiation and calcification of lens epithelial cells (LECs). We hypothesised that hyperglycaemia might promote the osteogenic differentiation of human LECs (HuLECs). Osteogenic medium (OM) containing excess phosphate and calcium with normal (1 g/L) or high (4.5 g/L) glucose was used to induce HuLEC calcification. High glucose accelerated and intensified OM-induced calcification of HuLECs, which was accompanied by hyperglycaemia-induced upregulation of the osteogenic markers Runx2, Sox9, alkaline phosphatase and osteocalcin, as well as nuclear translocation of Runx2. High glucose-induced calcification was abolished in Runx2-deficient HuLECs. Additionally, high glucose stabilised the regulatory alpha subunits of hypoxia-inducible factor 1 (HIF-1), triggered nuclear translocation of HIF-1α and increased the expression of HIF-1 target genes. Gene silencing of HIF-1α or HIF-2α attenuated hyperglycaemia-induced calcification of HuLECs, while hypoxia mimetics (desferrioxamine, CoCl2) enhanced calcification of HuLECs under normal glucose conditions. Overall, this study suggests that high glucose promotes HuLEC calcification via Runx2 and the activation of the HIF-1 signalling pathway. These findings may provide new insights into the pathogenesis of diabetic cataracts, shedding light on potential factors for intervention to treat this sight-threatening condition.

The Landscape of Osteocalcin Proteoforms Reveals Distinct Structural and Functional Roles of Its Carboxylation Sites.

Human osteocalcin (OC) undergoes reversible, vitamin K-dependent γ-carboxylation at three glutamic acid residues, modulating its release from bones and its hormonal roles. A complete understanding of OC roles and structure-activity relationships is still lacking, as only uncarboxylated and few differently carboxylated variants have been considered so far. To fill this lack of knowledge, a comprehensive experimental and computational investigation of the structural properties and calcium-binding activity of all the OC variants is reported here. Such a comparative study indicates that the carboxylation sites are not equivalent and differently affect the OC structure and interaction with calcium, properties that are relevant for the modulation of OC functions. This study also discloses cooperative effects and provides structural and mechanistic interpretation. The disclosed peculiar features of each carboxylated proteoform strongly suggest that considering all eight possible OC variants in future studies may help rationalize some of the conflicting hypotheses observed in the literature.

Chemically synthesized osteocalcin alleviates NAFLD via the AMPK-FOXO1/BCL6-CD36 pathway.

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease worldwide. Osteocalcin plays an important role in energy metabolism. In this study, we investigated the mechanism of action of chemically synthesized osteocalcin (csOCN) in ameliorating NAFLD. We demonstrated for the first time that csOCN attenuates lipid accumulation in the liver and hepatocytes by modulating CD36 protein expression. In addition, we found that the expression of p-AMPK, FOXO1 and BCL6 decreased and the expression of CD36 increased after OA/PA induction compared to the control group, and these effects were reversed by the addition of csOCN. In contrast, the therapeutic effect of csOCN was inhibited by the addition of AMPK inhibitors and BCL6 inhibitors. This finding suggested that csOCN regulates CD36 expression via the AMPK-FOXO1/BCL6 axis. In NAFLD mice, oral administration of csOCN also activated the AMPK pathway and reduced CD36 expression. Molecular docking revealed that osteocalcin has a docking site with CD36. Compared to oleic acid and palmitic acid, osteocalcin bound more strongly to CD36. Laser confocal microscopy results showed that osteocalcin colocalized with CD36 at the cell membrane. In conclusion, we demonstrated the regulatory role of csOCN in fatty acid uptake pathways for the first time; it regulates CD36 expression via the AMPK-FOXO1/BCL6 axis to reduce fatty acid uptake, and it affects fatty acid transport by may directly binding to CD36. There are indications that csOCN has potential as a CD36-targeted drug for the treatment of NAFLD.

Osteocalcin: A Multifaceted Bone-Derived Hormone.

Together, loss- and gain-of-function experiments have identified the bone-derived secreted molecule osteocalcin as a hormone with a broad reach in rodents and primates. Following its binding to one of three receptors, osteocalcin exerts a profound influence on various aspects of energy metabolism as well as steroidogenesis, neurotransmitter biosynthesis and thereby male fertility, electrolyte homeostasis, cognition, the acute stress response, and exercise capacity. Although this review focuses mostly on the regulation of energy metabolism by osteocalcin, it also touches on its other functions. Lastly, it proposes what could be a common theme between the functions of osteocalcin and between these functions and the structural functions of bone.

Reference limits for osteocalcin in infancy and early childhood: A longitudinal birth cohort study.

OBJECTIVE: The longitudinal variations in serum levels of the hormone osteocalcin is largely unknown during infancy and early childhood. Our aim was to establish reference limits for total serum osteocalcin during specific time points from birth until 5 years of age and present those in the context of sex, breastfeeding practices and gestational age (GA). DESIGN: Blood samples from 551 Swedish children were analysed at birth, 4, 12, 36 and 60 months of age. Total serum osteocalcin was measured using the IDS-iSYS N-MID Osteocalcin assay technique. Information about the mother, birth, anthropometrics and a food diary were collected. RESULTS: Sex-specific and age-specific reference limits were established for the five time points. The median osteocalcin levels over time were 40.8, 90.0, 67.8, 62.2 and 80.9 µg/L for boys and 38.1, 95.5, 78.3, 73.9 and 92.6 µg/L for girls. Lower GA was associated to higher osteocalcin at birth, and ongoing breastfeeding was associated to higher osteocalcin levels. CONCLUSION: Osteocalcin followed a wavelike pattern with low levels in the umbilical cord and a postnatal peak during the first year which then declined and rose again by the age of five. Knowledge of this wavelike pattern and association to factors as sex, breastfeeding and GA may help clinicians to interpret individual osteocalcin levels and guide in future research.

Pentoxifylline ameliorates subclinical atherosclerosis progression in patients with type 2 diabetes and chronic kidney disease: a randomized pilot trial.

BACKGROUND: Diabetic kidney disease (DKD) is associated with a higher risk of cardiovascular disease (CVD). Pentoxifylline (PTF), a nonselective phosphodiesterase inhibitor with anti-inflammatory, antiproliferative, and antifibrotic actions, has demonstrated renal benefits in both clinical trials and meta-analyses. The present work aimed to study the effects of PTF on the progression of subclinical atherosclerosis (SA) in a population of patients with diabetes and moderate to severe chronic kidney disease (CKD). METHODS: In this open-label, randomized controlled, prospective single-center pilot study the evolution of carotid intima-media thickness (CIMT) and ankle-brachial index (ABI) were determined in 102 patients with type 2 diabetes mellitus and CKD assigned to PTF, aspirin or control groups during 18 months. We also determined the variations in the levels of inflammatory markers and Klotho (KL), a protein involved in maintaining cardiovascular health, and their relationship with the progression of SA. RESULTS: Patients treated with PTF presented a better evolution of CIMT, increased KL mRNA levels in peripheral blood cells (PBCs) and reduced the inflammatory state. The progression of CIMT values was inversely related to variations in KL both in serum and mRNA expression levels in PBCs. Multiple regression analysis demonstrated that PTF treatment and variations in mRNA KL expression in PBCs, together with changes in HDL, were significant determinants for the progression of CIMT (adjusted R2 = 0.24, P < 0.001) independently of traditional risk factors. Moreover, both variables constituted protective factors against a worst progression of CIMT [OR: 0.103 (P = 0.001) and 0.001 (P = 0.005), respectively]. CONCLUSIONS: PTF reduced SA progression assessed by CIMT variation, a beneficial effect related to KL gene expression in PBCs. TRIAL REGISTRATION: The study protocol code is PTF-AA-TR-2009 and the trial was registered on the European Union Drug Regulating Authorities Clinical Trials (EudraCT #2009-016595-77). The validation date was 2010-03-09.

Echinacoside promotes osteogenesis and angiogenesis and inhibits osteoclast formation.

PURPOSE: The purpose of this research is to demonstrate echinacoside promotes osteogenesis and angiogenesis and inhibits osteoclast formation. METHODS: We conducted a cell experiment in vitro to study how echinacoside affects angiogenesis, osteogenesis and osteoclast formation. We used polymerase chain reaction and Western blotting to detect the expression levels of proteins and genes related to angiogenesis, osteogenesis and osteoclast formation. We established a bone fracture model with rats to test angiogenesis, osteogenesis and osteoclast formation of echinacoside. We labelled osteogenic markers, blood vessels and osteoclastic markers in fracture sections of rats. RESULTS: The in vitro cell experiments showed echinacoside improved the osteogenic activity of mouse embryo osteoblast precursor cells and promoted the migration and tube formation of human umbilical vein endothelial cells. In addition, it inhibited differentiation of mouse leukaemia cells of monocyte macrophage. Echinacoside increased the expression of related proteins and genes and improved angiogenesis and osteogenesis while inhibiting osteoclast formation by repressing the expression of related proteins and genes. From in vivo experiments, the results of IHC and HE experiments demonstrated echinacoside significantly decreased the content of MMP-9 and improved the content of VEGF and OCN. The fluorescence immunoassay showed echinacoside promoted the activities of RUNX2 and VEGF and inhibited CTSK. Echinacoside reduced the content of TNF-α, IL-1ß and IL-6, thus demonstrating its anti-inflammatory activity. CONCLUSION: Echinacoside improved angiogenesis and osteogenesis and inhibited osteoclast formation to promote fracture healing.

Lineage Tracing of RGS5-CreER-Labeled Cells in Long Bones During Homeostasis and Injury.

Regulator of G protein signaling 5 (RGS5) is a GTPase activator for heterotrimeric G-protein α-subunits, shown to be a marker of pericytes. Bone marrow stromal cell population (BMSCs) is heterogeneous. Populations of mesenchymal progenitors, cells supportive of hematopoiesis, and stromal cells regulating bone remodeling have been recently identified. Periosteal and bone marrow mesenchymal stem cells (MSCs) are participating in fracture healing, but it is difficult to distinguish the source of cells within the callus. Considering that perivascular cells exert osteoprogenitor potential, we generated an RGS5 transgenic mouse model (Rgs5-CreER) which when crossed with Ai9 reporter animals (Rgs5/Tomato), is suitable for lineage tracing during growth and post-injury. Flow cytometry analysis and histology confirmed the presence of Rgs5/Tomato+ cells within CD31+ endothelial, CD45+ hematopoietic, and CD31-CD45- mesenchymal/perivascular cells. A tamoxifen chase showed expansion of Rgs5/Tomato+ cells expressing osterix within the trabeculae positioned between mineralized matrix and vasculature. Long-term chase showed proportion of Rgs5/Tomato+ cells contributes to mature osteoblasts expressing osteocalcin. Following femoral fracture, Rgs5/Tomato+ cells are observed around newly formed bone within the BM cavity and expressed osterix and osteocalcin, while contribution within periosteum was low and limited to fibroblastic callus with very few positive chondrocytes. In addition, BM injury model confirmed that RGS5-Cre labels population of BMSCs expands during injury and participates in osteogenesis. Under homeostatic conditions, lineage-traced RGS5 cells within the trabecular area demonstrate osteoprogenitor capacity that in an injury model contributes to new bone formation primarily within the BM niche.

Prediabetes and insulin resistance: effect of vitamin D.

PURPOSE OF REVIEW: The impact of vitamin D on improving insulin resistance in prediabetes remains controversial. The purpose of this review is to examine whether vitamin D supplementation improves insulin resistance in adults with prediabetes, and if so, to identify the mechanisms and the specific populations. RECENT FINDINGS: Global prevalence of prediabetes is increasing, and prevention is a critical issue because these people with prediabetes will develop type 2 diabetes soon, which will put pressure on healthcare costs. Recent evidence on the effectiveness of vitamin D administration in improving insulin resistance and preventing the onset of type 2 diabetes in adults with prediabetes has been accumulating. The 2024 updated clinical practice guideline of the American Diabetes Association states that vitamin D administration to patients with prediabetes potentially benefits type 2 diabetes incidence in specific populations. There are also reports that vitamin D administration improves insulin resistance via increased serum osteocalcin levels, a marker of bone turnover. SUMMARY: Vitamin D is likely to improve insulin resistance, which is already present at the time of prediabetes. However, the effectiveness may vary depending on ethnic differences and blood vitamin D levels at the start of administration.

Interactions of the Osteokines, Glucose/Insulin System and Vascular Risk Networks in Patients With Newly Diagnosed Type 2 Diabetes (VNDS 15).

BACKGROUND AND AIM: Bone as an endocrine organ regulates metabolic processes independently of mineral metabolism through the production/release of proteins collectively named 'osteokines'. Relevant connections were reported between the insulin/glucose system, calcification of the atherosclerotic plaque, and several osteokines. We aimed to test the hypothesis that the osteokine network could be involved in beta-cell function, insulin sensitivity, and vascular damage in a cohort of people with newly diagnosed type 2 diabetes (T2D). SUBJECTS AND METHODS: In 794 drug-naive, GADA-negative, newly-diagnosed T2D patients (mean ± SD age: 59 ± 9.8 years; BMI: 29.3 ± 5.3 kg/m2; HbA1c: 6.6 ± 1.3%) we assessed: plasma concentration of osteocalcin (OCN), osteopontin (OPN), RANKL, and its putative decoy receptor osteoprotegerin (OPG); insulin sensitivity (SI) by hyperinsulinemic euglycemic clamp; beta cell function (BCF), estimated by OGTT minimal modelling and expressed as derivative (DC) and proportional (PC) control. Echo-doppler of carotid and lower limb arteries were also performed in 708 and 701 subjects, respectively. RESULTS: OCN, RANKL and OPG were significantly associated with PC (p < 0.02); OCN was positively related to DC (p = 0.018). OPG was associated with lower IS (p < 0.001). Finally, the higher RANKL levels, the greater was the severity of atherosclerosis in common carotid artery (p < 0.001). Increased OPG and OPN concentrations were related to subclinical atherosclerosis in peripheral arteries of lower limbs (p = 0.023 and p = 0.047, respectively). CONCLUSION: These data suggest that, in patients with newly diagnosed T2D, the osteokine network crosstalks with the glucose/insulin system and may play a role in modulating the atherosclerotic process.

Osteocalcin: Promoter or Inhibitor of Hydroxyapatite Growth?

Osteocalcin is the most abundant noncollagenous bone protein and the functions in bone remineralization as well as in inhibition of bone growth have remained unclear. In this contribution, we explain the dual role of osteocalcin in the nucleation of new calcium phosphate during bone remodeling and in the inhibition of hydroxyapatite crystal growth at the molecular scale. The mechanism was derived using pH-resolved all-atom models for the protein, phosphate species, and hydroxyapatite, along with molecular dynamics simulations and experimental and clinical observations. Osteocalcin binds to (hkl) hydroxyapatite surfaces through multiple residues, identified in this work, and the fingerprint of binding residues varies as a function of the (hkl) crystal facet and pH value. On balance, the affinity of osteocalcin to hydroxyapatite slows down crystal growth. The unique tricalcium γ-carboxylglutamic acid (Gla) domain hereby rarely adsorbs to hydroxyapatite surfaces and faces instead toward the solution. The Gla domain enables prenucleation of calcium phosphate for new bone formation at a slightly acidic pH of 5. The growth of prenucleation clusters of calcium phosphate continues upon increase in pH value from 5 to 7 and is much less favorable, or not observed, on the native osteocalcin structure at and above neutral pH values of 7. The results provide mechanistic insight into the early stages of bone remodeling from the molecular scale, help inform mutations of osteocalcin to modify binding to apatites, support drug design, and guide toward potential cures for osteoporosis and hyperosteogeny.

The Evolution of the Bone Turnover Marker in Patients Following Recovery from Diabetic Ketoacidosis.

The aim of the study was to investigate whether the biomarkers for bone turnover could rapidly recover during the period of diabetic ketoacidosis (DKA). Bone turnover biomarkers, including 25-hydroxyvitamin D3, N-terminal middle molecular fragment of osteocalcin (NMID), and ß-C terminal cross-linking telopeptide of type 1 collagen were evaluated using in-patient data (n=627) from Shanghai Pudong Hospital from 2018-2022. The comparison was performed between type 2 diabetes (T2D only) (n=602) and DKA (n=25), in which we checked the bone turnover markers at pre-treatment and recovery. After matching by body mass index (BMI), we found that except for 25-OH-VitD3, the age difference, indices of glucose metabolism, and bone turnover were significant between the 2 groups (p<0.05). We found only a significant restoration of NMID (p<0.001). NMID and ß-CTX, when compared with T2D, showed overt distinction between recovery and T2D (p<0.05). In addition, the investigations demonstrated a substantial difference between 25-OH-VitD3 in males and NMID in females, regardless of age (p<0.05). Multilinear regression analysis revealed that 2 hours postprandial plasma C-peptide was an independent predictor of the NMID in both pre-treatment (ß=0.58, p=0.003) and recovery (ß=0.447, p=0.025), although sex was significant in pre-treatment (ß=-0.444, p=0.020). Finally, we found that only age variation affected DKA's fasting plasma glucose level (p<0.05). The study revealed that the bone turnover of DKA is significantly different in pre-treatment and recovery; however, NMID might recover quickly if the patients received appropriate treatment. Importantly, pancreatic function plays a critical role in changing bone turnover biomarkers.

Mediating role of inflammatory biomarkers in the causal effect of body composition on glycaemic traits and type 2 diabetes.

OBJECTIVE: The aim was to investigate the mediating role of inflammatory biomarkers in the causal effect of body composition on glycaemic traits and type 2 diabetes. METHODS: A retrospective observational study and a Mendelian randomization (MR) study were used. Observational analyses were performed using data from 4717 Chinese children and adolescents aged 6-18 years who underwent dual-energy X-ray absorptiometry for body composition. MR analyses were based on summary statistics from UK Biobank, deCODE2021, Meta-Analysis of Glucose and Insulin-Related Traits Consortium (MAGIC) and other large consortiums. Inflammatory biomarkers included leptin, adiponectin, osteocalcin, fibroblast growth factor 23 (FGF23) and parathyroid hormone (PTH). RESULTS: In a retrospective observational study, increased fat mass had a positive effect on homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of pancreatic beta cell function (HOMA-ß) through FGF23, whereas fat-free mass produced the opposite effects. PTH and osteocalcin played significant roles in the association of fat mass and fat-free mass with fasting glucose, fasting insulin and HOMA-IR (all p < 0.05). Mediation MR results indicated that childhood body mass index affected glycaemic traits through leptin and adiponectin. There existed a causal effect of fat-free mass on type 2 diabetes via FGF23 (indirect effect: OR [odds ratio]: 1.14 [95% CI, confidence interval: 1.01-1.28]) and adiponectin (OR: 0.85 [95% CI: 0.77-0.93]). Leptin mediated the causal association of fat mass (indirect effect: ß: -0.05 [95% CI: -0.07, -0.02]) and fat-free mass (ß: 0.03 [95% CI: 0.01, 0.04]) with fasting glucose. CONCLUSIONS: Our findings suggest that different body compositions have differential influences on glycaemic traits and type 2 diabetes through distinct inflammatory biomarkers. The findings may be helpful in tailoring management of body composition based on inflammatory biomarkers with different glycaemic statuses.

Assessing the effects of probiotic supplementation, single strain versus mixed strains, on femoral mineral density and osteoblastic gene mRNA expression in rats.

INTRODUCTION: Osteoporosis is a significant health concern characterized by weak and porous bones, particularly affecting menopausal women aged 50 and above, leading to increased risk of hip fractures and associated morbidity and mortality. MATERIALS AND METHODS: We conducted a study to assess the efficacy of single-strain versus mixed-strain probiotic supplementation on bone health using an ovariectomy (OVX) rat model of induced bone loss. The probiotics evaluated were Lactobacillus helveticus (L. helveticus), Bifidobacterium longum (B. longum), and a combination of both. Rats were divided into five groups: SHAM (Control negative), OVX (Control positive), OVX +L. helveticus, OVX + B. longum, and OVX + mixed L. helveticus and B. longum. Daily oral administration of probiotics at 10^8-10^9 CFU/mL began two weeks post-surgery and continued for 16 weeks. RESULTS: Both single-strain and mixed-strain probiotic supplementation upregulated expression of osteoblastic genes (BMP- 2, RUNX-2, OSX), increased serum osteocalcin (OC) levels, and improved bone formation parameters. Serum C-terminal telopeptide (CTX) levels and bone resorption parameters were reduced. However, the single-strain supplementation demonstrated superior efficacy compared to the mixed-strain approach. CONCLUSION: Supplementation with B. longum and L. helveticus significantly reduces bone resorption and improves bone health in OVX rats, with single-strain supplementation showing greater efficacy compared to a mixed-strain combination. These findings highlight the potential of probiotics as a therapeutic intervention for osteoporosis, warranting further investigation in human studies.