Therapeutic potentials and modulatory mechanisms of fatty acids in bone

Is there a role for essential fatty acids in osteoporosis?

Inflammatory markers are inversely associated with bone density, geometry, and strength in postmenopausal women, and elderly subjects suggesting that osteoporosis is a low-grade systemic inflammatory condition. But glucocorticoids that are potent anti-inflammatory compounds instead of arresting/preventing osteoporosis induce osteoporosis. These results indicate that IL-6 and TNF-α, post-menopausal state, and steroids produce osteoporosis by an unidentified mechanism. Pro-inflammatory cytokines, estrogen, and steroids bring about their actions by influencing the metabolism of essential fatty acids (EFAs). I propose that EFAs and their metabolites act as second messengers of actions of corticosteroids, cytokines, and estrogen. This implies that EFAs are of benefit in the prevention and management of osteoporosis. This argument is supported by the observation that plasma phospholipid content of unsaturated fatty acids is decreased in those with osteoporosis. The reports that long-chain metabolites of EFAs including arachidonic acid, docosahexaenoic acid and eicosapentaenoic acid, and lipoxin A4 are of benefit in the prevention and management of osteoporosis lends further support to this proposal.

Acetyl-CoA-dependent ac4C acetylation promotes the osteogenic differentiation of LPS-stimulated BMSCs

The impaired osteogenic capability of bone marrow mesenchymal stem cells (BMSCs) caused by persistent inflammation is the main pathogenesis of inflammatory bone diseases. Recent studies show that metabolism is disturbed in osteogenically differentiated BMSCs in response to Lipopolysaccharide (LPS) treatment, while the mechanism involved remains incompletely revealed. Herein, we demonstrated that BMSCs adapted their metabolism to regulate acetyl-coenzyme A (acetyl-CoA) availability and RNA acetylation level, ultimately affecting osteogenic differentiation. The mitochondrial dysfunction and impaired osteogenic potential upon inflammatory conditions accompanied by the reduced acetyl-CoA content, which in turn suppressed N4-acetylation (ac4C) level. Supplying acetyl-CoA by sodium citrate (SC) addition rescued ac4C level and promoted the osteogenic capacity of LPS-treated cells through the ATP citrate lyase (ACLY) pathway. N-acetyltransferase 10 (NAT10) inhibitor remodelin reduced ac4C level and consequently impeded osteogenic capacity. Meanwhile, the osteo-promotive effect of acetyl-CoA-dependent ac4C might be attributed to fatty acid oxidation (FAO), as evidenced by activating FAO by L-carnitine supplementation counteracted remodelin-induced inhibition of osteogenesis. Further in vivo experiments confirmed the promotive role of acetyl-CoA in the endogenous bone regeneration in rat inflammatory mandibular defects. Our study uncovered a metabolic-epigenetic axis comprising acetyl-CoA and ac4C modification in the process of inflammatory osteogenesis of BMSCs and suggested a new target for bone tissue repair in the context of inflammatory bone diseases.

Dietary fatty acids and incident hip fractures in cohorts of women and men. A relative validation and follow-up study

OBJECTIVES

Hip fractures are associated with a high burden of morbidity and mortality. Diet is essential for preventing fragility fractures, but the role of dietary fatty acids on the risk of hip fracture is uncertain. The aim was to investigate how intake of different dietary fatty acids relates to the risk of hip fracture. A relative validation of the long-term intake of dietary fatty acids estimated from food frequency questionnaires (FFQs) was also performed.

DESIGN, SETTINGS AND PARTICIPANTS

We used data collected in two population-based cohorts, the Swedish Mammography Cohort and the Cohort of Swedish men (n = 83,603, 54% men, aged 45-82 years). Data from the repeated investigations in the cohorts and cross-sectional data from their clinical sub-cohorts were used.

MEASUREMENTS

Diet data was collected in FFQs. Incident hip fractures were gathered by individual linkage to national registers. We performed Cox regression analysis to investigate associations between dietary fatty acids and hip fracture. Follow-up time was between January 1st, 1998 and December 31st, 2020. The validation was performed using correlation analyses, comparing fatty acids measured in adipose tissue with estimated fatty acid intakes from FFQs.

RESULTS

During up to 23 years of follow-up (mean 18 years) and 1,538,627 person-years at risk, 7345 participants (2840 men) experienced a hip fracture. A low linoleic acid (LA) and high intakes of long-chain n-3 fatty acids were associated with higher hip fracture risk in a non-linear way. In quartile 4 compared to quartile 1 of LA, the multivariable-adjusted hazard ratio of hip fracture was 0.89 (95% Confidence Interval: 0.81, 0.97). The study confirmed the validity of FFQs to capture the intake of the specific dietary long-chain n-3 fatty acids. The estimated intake of LA, α-linolenic acid, and myristic acid were also adequately captured by the FFQs. Validity was confirmed in both women and men.

CONCLUSION

A low to moderate intake of linoleic acid and a higher intake of long-chain n-3 fatty acids were associated with a higher risk of hip fractures. The results indicate that attention should be paid to dietary fatty acid composition for the optimal prevention of fragility fractures.

Amino acid-based supramolecular chiral hydrogels promote osteogenesis of human dental pulp stem cells via the MAPK pathway

Critical-size defects (CSDs) of the craniofacial bones cause aesthetic and functional complications that seriously impact the quality of life. The transplantation of human dental pulp stem cells (hDPSCs) is a promising strategy for bone tissue engineering. Chirality is commonly observed in natural biomolecules, yet its effect on stem cell differentiation is seldom studied, and little is known about the underlying mechanism. In this study, supramolecular chiral hydrogels were constructed using L/d-phenylalanine (L/D-Phe) derivatives. The results of alkaline phosphatase expression analysis, alizarin red S assay, as well as quantitative real-time polymerase chain reaction and western blot analyses suggest that right-handed D-Phe hydrogel fibers significantly promoted osteogenic differentiation of hDPSCs. A rat model of calvarial defects was created to investigate the regulation of chiral nanofibers on the osteogenic differentiation of hDPSCs in vivo. The results of the animal experiment demonstrated that the D-Phe group exhibited greater and faster bone formation on hDPSCs. The results of RNA sequencing, vinculin immunofluorescence staining, a calcium fluorescence probe assay, and western blot analysis indicated that L-Phe significantly promoted adhesion of hDPSCs, while D-Phe nanofibers enhanced osteogenic differentiation of hDPSCs by facilitating calcium entry into cells and activate the MAPK pathway. These results of chirality-dependent osteogenic differentiation offer a novel therapeutic strategy for the treatment of CSDs by optimising the differentiation of hDPSCs into chiral nanofibers.

Bone Formation and Maintenance in Oral Surgery: The Decisive Role of the Immune System-A Narrative Review of Mechanisms and Solutions

Based on the evidence of a significant communication and connection pathway between the bone and immune systems, a new science has emerged: osteoimmunology. Indeed, the immune system has a considerable impact on bone health and diseases, as well as on bone formation during grafts and its stability over time. Chronic inflammation induces the excessive production of oxidants. An imbalance between the levels of oxidants and antioxidants is called oxidative stress. This physio-pathological state causes both molecular and cellular damage, which leads to DNA alterations, genetic mutations and cell apoptosis, and thus, impaired immunity followed by delayed or compromised wound healing. Oxidative stress levels experienced by the body affect bone regeneration and maintenance around teeth and dental implants. As the immune system and bone remodeling are interconnected, bone loss is a consequence of immune dysregulation. Therefore, oral tissue deficiencies such as periodontitis and peri-implantitis should be regarded as immune diseases. Bone management strategies should include both biological and surgical solutions. These protocols tend to improve immunity through antioxidant production to enhance bone formation and prevent bone loss. This narrative review aims to highlight the relationship between inflammation, oxidation, immunity and bone health in the oral cavity. It intends to help clinicians to detect high-risk situations in oral surgery and to propose biological and clinical solutions that will enhance patients' immune responses and surgical treatment outcomes.

Transcriptomic and proteomic strategies to reveal the mechanism of Gymnocypris przewalskii scale development

BACKGROUND

Fish scales are typical products of biomineralization and play an important role in the adaptation of fish to their environment. The Gymnocypris przewalskii scales are highly specialized, with scales embedded in only specific parts of the dermis, such as the areas around the anal fin and branchiostegite, making G. przewalskii an ideal material for biomineralization research. In this study, we aimed to unveil genes and pathways controlling scale formation through an integrated analysis of both transcriptome and proteome, of which G. przewalskii tissues of the dorsal skin (no scales) and the rump side skin (with scales) were sequenced. The sequencing results were further combined with cellular experiments to clarify the relationship between genes and signaling pathways.

RESULTS

The results indicated the following: (1) a total of 4,904 differentially expressed genes were screened out, including 3,294 upregulated genes and 1,610 downregulated genes (with a filtering threshold of |log2Fold-Change|> 1 and p-adjust < 0.05). The identified differentially expressed genes contained family members such as FGF, EDAR, Wnt10, and bmp. (2) A total of 535 differentially expressed proteins (DEPs) were filtered out from the proteome, with 204 DEPs downregulated and 331 DEPs upregulated (with a filtering threshold of |Fold-Change|> 1.5 and p < 0.05). (3) Integrated analyses of transcriptome and proteome revealed that emefp1, col1a1, col6a2, col16a1, krt8, and krt18 were important genes contributing to scale development and that PI3K-AKT was the most important signaling pathway involved. (4) With the use of the constructed G. przewalskii fibroblast cell line, emefp1, col1a1, col6a2, col16a1, krt8, and krt18 were confirmed to be positively regulated by the PI3K-AKT signaling pathway.

CONCLUSION

This study provides experimental evidence for PI3K-AKT controlled scale development in G. przewalskii and would benefit further study on stress adaptation, scale biomineralization, and the development of skin appendages.

Serum phospholipid fatty acids are associated with bone mass in healthy 4-years-old children

BACKGROUND

Fatty acids are involved in bone development but knowledge in children is limited. The aim of this study was to investigate bone mass and mineral density in healthy preschool children in relation to fatty acids.

MATERIAL AND METHODS

In 111 healthy 4-yrs-old children (20 % overweight) bone was analysed by dual X-ray absorptiometry and serum phospholipid fatty acid by gas chromatography. Fat intake was calculated from 7 days self-reported dietary records and food frequency questionnaire.

RESULTS

Total bone mass content (BMC) and mineral density (BMD) differed by sex in normal weight, but not in overweight children showing generally higher bone mass density than children with normal weight. Linoleic acid intake was strongly correlated to BMC and femoral BMD in normal weight children. Serum concentration of docosahexaenoic acid correlated positively to BMD in all children (p = 0.01), but linoleic and arachidonic acids, and monounsaturated fatty acids showed diverging associations with bone in normal weight and overweight children.

CONCLUSION

Serum phospholipid DHA was associated with bone density. Other fatty acids associations to bone sites differed in overweight children, analogue to the pattern in healthy 8-yrs-old.The finding need to be confirmed longitudinally and in a larger group of overweight individuals.

Exploring Omega-3's Impact on the Expression of Bone-Related Genes in Meagre (Argyrosomus regius)

Dietary supplementation with Omega-3 fatty acids seems to promote skeletal health. Therefore, their consumption at imbalanced or excessive levels has offered less beneficial or even prejudicial effects. Fish produced in aquaculture regimes are prone to develop abnormal skeletons. Although larval cultures are usually fed with diets supplemented with Omega-3 Long Chain Polyunsaturated fatty acids (LC-PUFAs), the lack of knowledge about the optimal requirements for fatty acids or about their impact on mechanisms that regulate skeletal development has impeded the design of diets that could improve bone formation during larval stages when the majority of skeletal anomalies appear. In this study, Argyrosomus regius larvae were fed different levels of Omega-3s (2.6% and 3.6% DW on diet) compared to a commercial diet. At 28 days after hatching (DAH), their transcriptomes were analyzed to study the modulation exerted in gene expression dynamics during larval development and identify impacted genes that can contribute to skeletal formation. Mainly, both levels of supplementation modulated bone-cell proliferation, the synthesis of bone components such as the extracellular matrix, and molecules involved in the interaction and signaling between bone components or in important cellular processes. The 2.6% level impacted several genes related to cartilage development, denoting a special impact on endochondral ossification, delaying this process. However, the 3.6% level seemed to accelerate this process by enhancing skeletal development. These results offered important insights into the impact of dietary Omega-3 LC-PUFAs on genes involved in the main molecular mechanism and cellular processes involved in skeletal development.

Metabolic bone disorders and the promise of marine osteoactive compounds

Metabolic bone disorders and associated fragility fractures are major causes of disability and mortality worldwide and place an important financial burden on the global health systems. These disorders result from an unbalance between bone anabolic and resorptive processes and are characterized by different pathophysiological mechanisms. Drugs are available to treat bone metabolic pathologies, but they are either poorly effective or associated with undesired side effects that limit their use. The molecular mechanism underlying the most common metabolic bone disorders, and the availability, efficacy, and limitations of therapeutic options currently available are discussed here. A source for the unmet need of novel drugs to treat metabolic bone disorders is marine organisms, which produce natural osteoactive compounds of high pharmaceutical potential. In this review, we have inventoried the marine osteoactive compounds (MOCs) currently identified and spotted the groups of marine organisms with potential for MOC production. Finally, we briefly examine the availability of in vivo screening and validation tools for the study of MOCs.

Novel Insights into Osteoclast Energy Metabolism

PURPOSE OF REVIEW

Osteoclasts are crucial for the dynamic remodeling of bone as they resorb old and damaged bone, making space for new bone. Metabolic reprogramming in these cells not only supports phenotypic changes, but also provides the necessary energy for their highly energy-consuming activity, bone resorption. In this review, we highlight recent developments in our understanding of the metabolic adaptations that influence osteoclast behavior and the overall remodeling of bone tissue.

RECENT FINDINGS

Osteoclasts undergo metabolic reprogramming to meet the energy demands during their transition from precursor cells to fully mature bone-resorbing osteoclasts. Recent research has made considerable progress in pinpointing crucial metabolic adaptations and checkpoint proteins in this process. Notably, glucose metabolism, mitochondrial biogenesis, and oxidative respiration were identified as essential pathways involved in osteoclast differentiation, cytoskeletal organization, and resorptive activity. Furthermore, the interaction between these pathways and amino acid and lipid metabolism adds to the complexity of the process. These interconnected processes can function as diverse fuel sources or have independent regulatory effects, significantly influencing osteoclast function. Energy metabolism in osteoclasts involves various substrates and pathways to meet the energetic requirements of osteoclasts throughout their maturation stages. This understanding of osteoclast biology may provide valuable insights for modulating osteoclast activity during the pathogenesis of bone-related disorders and may pave the way for the development of innovative therapeutic strategies.

Bone mineral density and muscle mass associated with healthy eating index in postmenopausal women; results from RaNCD cohort study

BACKGROUND

The Healthy Eating Index 2015 (HEI-2015) is a tool for checking the quality of diet. This index is used to examine how well people's dietary behavior fits certain criteria for achieving a healthy diet in Dietary Guidelines for Americans 2015-2020. We look at the possible association between the HEI-2015 and bone mineral density (BMD) and muscle strength in postmenopausal women.

METHODS

This research included 1012 postmenopausal women from the recruitment phase of the Ravansar Noncommunicable Diseases (RaNCD) cohort study in Kermanshah-Iran. A standardized and repeatable food-frequency questionnaire (FFQ) that contains 118 items was used to quantify dietary consumption. Anthropometric indices measured via Bio-Impedance Analyzer BIA (Inbody 770, Inbody Co, Seoul, Korea).

RESULT

The mean age of postmenopausal women was (56.41 ± 5.31) years. Participants in the highest quartile had a more daily energy intake compared to the lowest quartile (2329.89 ± 837.59), (P < 0.001). Women in the upper quartiles had greater Skeletal Muscle Mass (SMM) than those in the lower quartiles (21.61 ± 2.80 vs 20.52 ± 3.13; p = 0.0002). The linear model didn't show a significant relationship between HEI score and greater BMD (β = 0.0014, P = 0.169).

CONCLUSION

A diet of high quality followed by a high HEL-2015 score was shown to be strongly connected to increased BMD and muscle mass in Kurdish postmenopausal women.

Recent Advance in Regulatory Effect of GRP120 on Bone Metabolism

The link between fatty acids and bone metabolism is complex and can be direct and indirect. This link has been reported in different types of bone cells and various stages of bone metabolism. G-protein coupled receptor 120 (GPR120), also called free fatty acid receptor 4 (FFAR4), is a member of the recently discovered G protein-coupled receptor family that can interact with both long-chain saturated fatty acids (C14-C18) and long-chain unsaturated fatty acids (C16-C22). Research shows that GPR120 regulates processes in different types of bone cells, directly or indirectly affecting bone metabolism. Our research reviewed the literature on the effects of GPR120 on bone marrow mesenchymal stem cells (BMMSCs), osteoblasts, osteoclasts, and chondrocytes, focusing on the research findings regarding the mechanism by which GPR120 alters specific bone metabolic diseases-osteoporosis and osteoarthritis. The data reviewed here provide a basis for clinical and basic research into the role of GPR120 on bone metabolic diseases.

Bone marrow fatty acids affect osteoblastic differentiation through miR-92b-3p in the early stages of postmenopausal osteoporosis

Osteoporosis is partially caused by dysfunctions in the commitment, differentiation or survival of osteoblasts. Bone marrow fatty acids affect bone resorption and formation. In this study, we aimed to explore the role of fatty acids in the early stages of postmenopausal osteoporosis and determine whether they influence osteogenic differentiation through microRNAs. A quantitative analysis of bone marrow fatty acids early after ovariectomy or sham surgery in a rat osteoporotic model was performed using gas chromatography/mass spectrometry. The results showed that palmitoleate was significantly decreased on postoperative day 3 while both pentadecanoate and palmitoleate were significantly decreased on postoperative day 5 in rats in the ovariectomized group compared with those in the sham group. Palmitoleate promotes osteogenic differentiation, whereas pentadecanoate inhibits this process. Palmitoleate levels were higher than those of pentadecanoate; therefore, the early overall effect of significant bone marrow fatty acid changes was a decrease in osteogenic differentiation. We also found that miR-92b-3p inhibited osteoblastogenesis via the miR-92b-3p/phosphatase and tensin homolog regulatory axis. Palmitoleate, pentadecanoate, and palmitate influenced the osteoblastogenesis of MC3T3-E1 cells through miR-92b-3p. Taken together, we propose that miR-92b-3p mediates the effect of bone marrow fatty acids on osteoblast differentiation in the early stages of osteoporosis. These findings may provide molecular insights for the treatment of osteoporosis.

Maresin1: A multifunctional regulator in inflammatory bone diseases

Inflammation plays a crucial role in the physical response to danger signals, the elimination of toxic stimuli, and the restoration of homeostasis. However, dysregulated inflammatory responses lead to tissue damage, and chronic inflammation can disrupt osteogenic-osteoclastic homeostasis, ultimately leading to bone loss. Maresin1 (MaR1), a member of the specialized pro-resolving mediators (SPMs) family, has been found to possess significant anti-inflammatory, anti-allergic, pro-hemolytic, pro-healing, and pain-relieving properties. MaR1 is synthesized by macrophages (Mφs) and omega-3 fatty acids, and it may have the potential to promote bone homeostasis and treat inflammatory bone diseases. MaR1 has been found to stimulate osteoblast proliferation through leucine-rich repeat G protein-coupled receptor 6 (LGR6). It also activates Mφ phagocytosis and M2-type polarization, which helps to control the immune system. MaR1 can regulate T cells to exert anti-inflammatory effects and inhibit neutrophil infiltration and recruitment. In addition, MaR1 is involved in antioxidant signaling, including nuclear factor erythroid 2-related factor 2 (NRF2). It has also been found to promote the autophagic behavior of periodontal ligament stem cells, stimulate Mφs against pathogenic bacteria, and regulate tissue regeneration and repair. In summary, this review provides new information and a comprehensive overview of the critical roles of MaR1 in inflammatory bone diseases, indicating its potential as a therapeutic approach for managing skeletal metabolism and inflammatory bone diseases.

Increased n-6 Polyunsaturated Fatty Acids Indicate Pro- and Anti-Inflammatory Lipid Modifications in Synovial Membranes with Rheumatoid Arthritis

Emerging evidence suggests that fatty acids (FAs) and their lipid mediator derivatives can induce both beneficial and detrimental effects on inflammatory processes and joint degradation in osteoarthritis (OA) and autoimmune-driven rheumatoid arthritis (RA). The present study characterized the detailed FA signatures of synovial membranes collected during knee replacement surgery of age- and gender-matched OA and RA patients (n = 8/diagnosis). The FA composition of total lipids was determined by gas chromatography and analyzed with univariate and multivariate methods supplemented with hierarchical clustering (HC), random forest (RF)-based classification of FA signatures, and FA metabolism pathway analysis. RA synovium lipids were characterized by reduced proportions of shorter-chain saturated FAs (SFAs) and elevated percentages of longer-chain SFAs and monounsaturated FAs, alkenyl chains, and C20 n-6 polyunsaturated FAs compared to OA synovium lipids. In HC, FAs and FA-derived variables clustered into distinct groups, which preserved the discriminatory power of the individual variables in predicting the RA and OA inflammatory states. In RF classification, SFAs and 20:3n-6 were among the most important FAs distinguishing RA and OA. Pathway analysis suggested that elongation reactions of particular long-chain FAs would have increased relevance in RA. The present study was able to determine the individual FAs, FA groups, and pathways that distinguished the more inflammatory RA from OA. The findings suggest modifications of FA elongation and metabolism of 20:4n-6, glycerophospholipids, sphingolipids, and plasmalogens in the chronically inflamed RA synovium. These FA alterations could have implications in lipid mediator synthesis and potential as novel diagnostic and therapeutic tools.

Obesity, but not high-fat diet, is associated with bone loss that is reversed via CD4+CD25+Foxp3+ Tregs-mediated gut microbiome of non-obese mice

Osteoporosis is characterized by decreased bone mass, microarchitectural deterioration, and increased bone fragility. High-fat diet (HFD)-induced obesity also results in bone loss, which is associated with an imbalanced gut microbiome. However, whether HFD-induced obesity or HFD itself promotes osteoclastogenesis and consequent bone loss remains unclear. In this study, we developed HFD-induced obesity (HIO) and non-obesity (NO) mouse models to evaluate the effect of HFD on bone loss. NO mice were defined as body weight within 5% of higher or lower than that of chow diet fed mice after 10 weeks HFD feeding. NO was protected from HIO-induced bone loss by the RANKL /OPG system, with associated increases in the tibia tenacity, cortical bone mean density, bone volume of cancellous bone, and trabecular number. This led to increased bone strength and improved bone microstructure via the microbiome-short-chain fatty acids (SCFAs) regulation. Additionally, endogenous gut-SCFAs produced by the NO mice activated free fatty acid receptor 2 and inhibited histone deacetylases, resulting in the promotion of Treg cell proliferation in the HFD-fed NO mice; thereby, inhibiting osteoclastogenesis, which can be transplanted by fecal microbiome. Furthermore, T cells from NO mice retain differentiation of osteoclast precursors of RAW 264.7 macrophages ex vivo. Our data reveal that HFD is not a deleterious diet; however, the induction of obesity serves as a key trigger of bone loss that can be blocked by a NO mouse-specific gut microbiome.

Equine osteoarthritis modifies fatty acid signatures in synovial fluid and its extracellular vesicles

BACKGROUND

Individual fatty acids (FAs) and their derivatives (lipid mediators) with pro-inflammatory or dual anti-inflammatory and pro-resolving properties have potential to influence the health of joint tissues. Osteoarthritis (OA) is an age-associated chronic joint disease that can be featured with altered FA composition in the synovial fluid (SF) of human patients. The counts and cargo of extracellular vesicles (EVs), membrane-bound particles released by synovial joint cells and transporting bioactive lipids, can also be modified by OA. The detailed FA signatures of SF and its EVs have remained unexplored in the horse - a well-recognized veterinary model for OA research.

METHODS

The aim of the present study was to compare the FA profiles in equine SF and its ultracentrifuged EV fraction between control, contralateral, and OA metacarpophalangeal joints (n = 8/group). The FA profiles of total lipids were determined by gas chromatography and the data compared with univariate and multivariate analyses.

RESULTS

The data revealed distinct FA profiles in SF and its EV-enriched pellet that were modified by naturally occurring equine OA. Regarding SFs, linoleic acid (generalized linear model, p = 0.0006), myristic acid (p = 0.003), palmitoleic acid (p < 0.0005), and n-3/n-6 polyunsaturated FA ratio (p < 0.0005) were among the important variables that separated OA from control samples. In EV-enriched pellets, saturated FAs palmitic acid (p = 0.020), stearic acid (p = 0.002), and behenic acid (p = 0.003) indicated OA. The observed FA modifications are potentially detrimental and could contribute to inflammatory processes and cartilage degradation in OA.

CONCLUSIONS

Equine OA joints can be distinguished from normal joints based on their FA signatures in SF and its EV-enriched pellet. Clarifying the roles of SF and EV FA compositions in the pathogenesis of OA and their potential as joint disease biomarkers and therapeutic targets warrants future studies.

α-Linolenic Acid Inhibits RANKL-Induced Osteoclastogenesis In Vitro and Prevents Inflammation In Vivo

Inflammation is an important risk factor for bone-destroying diseases. Our preliminary research found that Zanthoxylum bungeanum seed oil (ZBSO) is abundant in unsaturated fatty acids and could inhibit osteoclastogenesis in receptor activator of nuclear factor κB ligand (RANKL)-induced RAW264.7 cells. However, the key constituents in ZBSO in the prevention of osteoclastogenesis and its possible mechanism related to inflammation are still unclear. Therefore, in this study, oleic acid (OA), linoleic acid (LA), palmitoleic acid (PLA), and alpha-linolenic acid (ALA) in ZBSO, havingthe strongest effect on RANKL-induced osteoclastogenesis, were selected by a tartrate-resistant acid phosphatase (TRAP) staining method. Furthermore, the effects of the selected fatty acids on anti-inflammation and anti-osteoclastogenesis in vitro and in vivo were assessed using RT-qPCR. Among the four major unsaturated fatty acids we tested, ALA displayed the strongest inhibitory effect on osteoclastogenesis. The increased expression of free fatty acid receptor 4 (FFAR4) and β-arrestin2 (βarr2), as well as the decreased expression of nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), nuclear factor of activated T-cells c1 (NFATc1), and tartrate-resistant acid phosphatase (TRAP) in RAW264.7 cells after ALA treatment were observed. Moreover, in ovariectomized osteoporotic rats with ALA preventive intervention, we found that the expression of TNF-α, interleukin-6 (IL-6), interleukin-1β (IL-1β), NFATc1, and TRAP were decreased, while with the ALA therapeutic intervention, downregulated expression of NF-κB, NFATc1, TRAP, and transforming growth factor beta-activated kinase 1 (TAK1) were noticed. These results indicate that ALA, as the major unsaturated fatty acid in ZBSO, could inhibit RANKL-induced osteoclastogenesis via the FFAR4/βarr2 signaling pathway and could prevent inflammation, suggesting that ZBSO may be a promising potential natural product of unsaturated fatty acids and a dietary supplement for the prevention of osteoclastogenesis and inflammatory diseases.

Hyperlipidemia impacts osteogenesis via lipophagy

The mechanism of the impact of hyperlipidemia on bone tissue homeostasis is unclear, and the role of lipophagy is yet to be investigated. This study investigated changes in lipophagy and osteogenesis levels under hyperlipemic conditions and explored the effects of lipophagy on bone regeneration. In vivo, femurs of mice with diet-induced moderate hyperlipidemia were ground out with a ball drill to create defects. In vitro, mouse osteoblast cell lines were grown in two different concentrations of the high-fat medium. We found that at hyperphysiological of lipid conditions, activation of lipophagy restored osteoblast function in a way, and similar results were observed in mice with diet-induced hyperlipidemia. Still, at suprahyperphysiological concentrations of lipid culture, the activation of lipophagy further inhibited osteogenesis, and inhibition of autophagy instead promoted osteogenesis to a small extent. These results demonstrate that lipophagy functions differently in diverse high-fat environments, suggesting that cellular and organismal changes in response to high-fat stimuli are dynamic. This may provide new ideas for improving bone dysfunction caused by lipid metabolism disorders.

Er-Xian decoction attenuates ovariectomy-induced osteoporosis by modulating fatty acid metabolism and IGF1/PI3K/AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Er-Xian decoction (EXD) is a traditional Chinese medicine (TCM) formula used to treat osteoporosis (OP). However, the anti-OP mechanism of EXD has not yet been fully elucidated.

AIM OF THE STUDY

The study aimed to verify the anti-OP effect of EXD and to explore its underlying mechanism.

METHODS

The anti-OP targets and mechanisms of EXD were predicted by network pharmacological analysis. Then, an ovariectomized (OVX) rat model was established to validate the key anti-OP mechanism of EXD. Firstly, the therapeutic effect of EXD on OP was confirmed using micro-CT bone analysis, pathological observation, and ELISA detection. Secondly, serum metabolites related to key biological processes were detected using an automatic biochemical analyzer and GC-MS. Finally, ELISA, qRT-PCR, and western blot were utilized to further explore the potential key anti-OP pathway of EXD.

RESULTS

A total of 159 anti-OP targets of EXD were identified. Functional annotation revealed that OP treatment using EXD was associated with lipid metabolism, fatty acid (FA) metabolism, and PI3K/AKT signaling pathway. Experimental studies confirmed that EXD ameliorated ovariectomy-induced bone loss and bone microstructure deterioration. EXD treatment also upregulated the level of serum estrogen and downregulated the level of OC, PⅠNP, CTX-1, TC, and LDL-C. Besides, principal component analysis (PCA) and heat map of serum FAs distinguished OVX rats from the SHAM and EXD groups. Serum concentrations of important n-3 FAs, including C20:3N3, C20:5N3, and C22:5N3, were significantly increased in the EXD group. The increased stearoyl-CoA desaturase 1 (SCD1) index 1 and index 2 in the OVX group were reversed by EXD administration. Additionally, EXD reversed the decreased serum IGF1 level and tibia IGF1R, PI3K, and AKT expression in OVX rats.

CONCLUSION

EXD ameliorated ovariectomy-induced bone loss by modulating lipid metabolism, FA metabolism, and IGF1/PI3K/AKT pathway.

Targeting soluble epoxide hydrolase promotes osteogenic-angiogenic coupling via activating SLIT3/HIF-1α signalling pathway

Type H vessels have recently been identified to modulate osteogenesis. Epoxyeicostrioleic acids (EETs) have an essential contribution to vascular homeostasis. However, whether increased EETs with soluble epoxide hydrolase (sEH) inhibitor TPPU enhance the coupling of angiogenesis and osteogenesis remains largely unknown. The effects of TPPU on cross-talk between co-cultured human umbilical vein endothelial cells (HUVECs) and human dental pulp stem cells (hDPSCs), and on long bone growth and calvarial defect repair in mice were investigated in vitro and in vivo. TPPU enhanced osteogenic differentiation of co-cultured HUVECs and hDPSCs in vitro and increased type H vessels, and long bone growth and bone repair of calvarial defect. Mechanistically, TPPU promoted cell proliferation and angiogenesis, reclined cell apoptosis, and significantly increased CD31^hi EMCN^hi endothelial cells (ECs) and SLIT3 and HIF-1α expression levels in co-cultured HUVECs and hDPSCs. Knockdown of Slit3 in hDPSCs or Hif-1α in HUVECs impaired the formation of CD31^hi EMCN^hi ECs and reversed TPPU-induced osteogenesis. We defined a previously unidentified effect of TPPU coupling angiogenesis and osteogenesis. TPPU induced type H vessels by upregulating the expression of hDPSCs-derived SLIT3, which resulted in the activation of ROBO1/YAP1/HIF-1α signalling pathway in ECs. Targeting metabolic pathways of EETs represents a new strategy to couple osteogenesis and angiogenesis, sEH is a promising therapeutic target for bone regeneration and repair.

The benefits of adipocyte metabolism in bone health and regeneration

Patients suffering from musculoskeletal diseases must cope with a diminished quality of life and an increased burden on medical expenses. The interaction of immune cells and mesenchymal stromal cells during bone regeneration is one of the key requirements for the restoration of skeletal integrity. While stromal cells of the osteo-chondral lineage support bone regeneration, an excessive accumulation of cells of the adipogenic lineage is thought to promote low-grade inflammation and impair bone regeneration. Increasing evidence indicates that pro-inflammatory signaling from adipocytes is responsible for various chronic musculoskeletal diseases. This review aims to summarize the features of bone marrow adipocytes by phenotype, function, secretory features, metabolic properties and their impact on bone formation. In detail, the master regulator of adipogenesis and prominent diabetes drug target, peroxisome proliferator-activated receptor γ (PPARG), will be debated as a potential therapeutic approach to enhance bone regeneration. We will explore the possibilities of using clinically established PPARG agonists, the thiazolidinediones (TZDs), as a treatment strategy to guide the induction of a pro-regenerative, metabolically active bone marrow adipose tissue. The impact of this PPARG induced bone marrow adipose tissue type on providing the necessary metabolites to sustain osteogenic-as well as beneficial immune cells during bone fracture healing will be highlighted.

Changes in Bone Marrow Fatty Acids Early after Ovariectomy-Induced Osteoporosis in Rats and Potential Functions

The aim of this study was to investigate the changes in bone marrow fatty acids early after ovariectomy-induced osteoporosis in rats, and explore the potential function of the bone marrow fatty acids. Ninety-six female Sprague Dawley rats (12 weeks) were randomly divided into an ovariectomized (OVX) group and Sham group (N = 48/group) and received ovariectomy or Sham surgery, respectively. After 3, 5, 7,14, 21 and 28 days, eight rats in each group were sacrificed to detect the composition of bone marrow fatty acids by means of gas chromatography-mass spectrometry and evaluate the trabecular bone microarchitecture by means of microCT. Bone marrow rinsing fluid and serum were collected for the detection of nitric oxide synthase/nitric oxide (NOS/NO) and bone metabolism related parameters, respectively. Our results demonstrated that the bone microstructure was damaged significantly from 14 days after OVX surgery onwards. Sample clustering and group separation were observed between the OVX group and Sham group 3 and 14 days after surgery, which suggested the role of bone marrow fatty acids in the early stage of postmenopausal osteoporosis. Palmitoleate, myristate and arachidonate were found to play an important role in classification between the OVX group and Sham group on the 3rd day after surgery (VIP > 1, p < 0.05). Palmitoleate, myristate, alpha linolenate, stearate and eicosenoate were found to play an important role in classification between the OVX group and Sham group on the 14th day after surgery (VIP > 1, p < 0.05). The levels of myristate, palmitoleate, alpha linolenate and eicosenoate were significantly decreased in the OVX group, while the levels of arachidonate and stearate were significantly increased in OVX group (p < 0.05). Additionally, myristate, palmitoleate, alpha linoleate and eicosenoate were negatively correlated with C-terminal telopeptide of type 1 collagen (CTX-1, a bone resorption marker), while arachidonate was negative correlated with osteocalcin (OCN, a bone formation marker) (p < 0.05). A significant correlation was also found between eicosenoate and NOS (p < 0.05). Profound bone marrow fatty acids changes have taken place in the early stage of post-menopausal osteoporosis. They may affect bone formation though affecting the differentiation and function of osteoclasts or osteoblasts, respectively. The NOS/NO system may mediate the influence of eicosenoate on bone formation.

Bone loss is ameliorated by fecal microbiota transplantation through SCFA/GPR41/ IGF1 pathway in sickle cell disease mice

Bone loss is common in sickle cell disease (SCD), but the molecular mechanisms is unclear. Serum insulin-like growth factor 1 (IGF1) was low in SCD subjects and SCD mice. To determine if decreased IGF1 associated with low bone mass in SCD is due to reduced SCFA production by gut microbiota, we performed reciprocal fecal microbiota transplantation (FMT) between healthy control (Ctrl) and SCD mice. uCT and histomorphometry analysis of femur showed decreased bone volume/total volume (BV/TV), trabecular number (Tb.N), osteoblast surface/bone surface (Ob.S/BS), mineralizing surface/ bone surface (MS/BS), inter-label thickness (Ir.L.Th) in SCD mice were significantly improved after receiving Ctrl feces. Bone formation genes Alp, Col1, Runx2, and Dmp1 from SCD mice were significantly decreased and were rescued after FMT from Ctrl feces. Transplantation of Ctrl feces increased the butyrate, valerate, and propionate levels in cecal content of SCD mice. Decreased G-coupled protein receptors 41 and 43 (GPR41 and GPR43) mRNA in tibia and lower IGF1 in bone and serum of SCD mice were partially restored after FMT from Ctrl feces. These data indicate that the healthy gut microbiota of Ctrl mice is protective for SCD bone loss through regulating IGF1 in response to impaired bacterial metabolites SCFAs.

Dietary Diversity, Micronutrient Adequacy and Bone Status during Pregnancy: A Study in Urban China from 2019 to 2020

Diet quality during reproduction is crucial to maternal and infant health. However, the association between dietary diversity and bone health of pregnant women remains unclear. We aimed to evaluate the dietary quality of Chinese urban gravidas using the dietary diversity score (DDS), and to explore the relationship of the DDS with micronutrient adequacy and bone health. In this cross-sectional study, we analyzed data from 775 pregnant women aged 18 years or older in urban China. Dietary diversity was assessed using the Minimum Dietary Diversity for Women (MDD-W) indicator. A 24-h dietary recall was used to collect diet data and to calculate the MDD-W and the nutrient intake. Bone health was measured using quantitative ultrasound and assessed by the speed of sound (SOS). Pearson's correlation coefficients between the DDS and the nutrient adequacy ratio (NAR) were calculated. A multivariable linear regression model was used to estimate the effect size of the DDS on the SOS. The mean DDS was 6.61 ± 1.53 points and 91.0% of participants reported the consumption of five or more food groups. Women in the diverse diet subgroup (DDS ≥ 7 points) were more likely to consume all kinds of food except starchy staples and had higher NARs. Pearson's correlation coefficients between the DDS and the NAR ranged from 0.161 to 0.484. For participants in the second trimester, those with a diverse diet had a higher SOS. A multivariable linear regression analysis showed that the DDS was positively and significantly associated with the SOS (β = 17.18, 95% CI = 5.97-28.39, p = 0.003), but this was not the case for women in the first and third trimesters. Urban Chinese women had good dietary diversity during pregnancy. A higher dietary diversity was associated with a higher NAR. From the point of view of bone, a diverse diet was positively correlated with better bone status, suggesting the importance of improving diet diversity for pregnant women, especially from mid-pregnancy.

PPAR agonists attenuate lenalidomide's anti-myeloma activity in vitro and in vivo

Many patients with multiple myeloma (MM) have comorbidities and are treated with PPAR agonists. Immunomodulatory agents (IMiDs) are the cornerstones for MM therapy. Currently, little is known about how co-administration of PPAR agonists impacts lenalidomide treatment in patients with MM. Here, we determined the effects of PPAR agonists on anti-myeloma activities of lenalidomide in vitro and in a myeloma xenograft mouse model. Genetic overexpression and CRISPR/cas9 knockout experiments were performed to determine the role of CRBN in the PPAR-mediated pathway. A retrospective cohort study was performed to determine the correlation of PPAR expression with the outcomes of patients with MM. PPAR agonists down-regulated CRBN expression and reduced the anti-myeloma efficacy of lenalidomide in vitro and in vivo. Co-treatment with PPAR antagonists increased CRBN expression and improved sensitivity to lenalidomide. PPAR expression was higher in bone marrow cells of patients with newly diagnosed MM than in normal control bone marrow samples. High PPAR expression was correlated with poor clinical outcomes. Our study provides the first evidence that PPARs transcriptionally regulate CRBN and that drug-drug interactions between PPAR agonists and IMiDs may impact myeloma treatment outcomes.

Dietary Saturated Fat and Bone Health in Young Adults: The Young Finns Cohort

Previous studies suggest that saturated fat (SFA) intake may negatively impact on bone. However, few human studies on the topic exist. Women and men aged 31-46 years from the Cardiovascular Risk in Young Finns study attended the peripheral quantitative computed tomography and ultrasound bone measurements in 2008 (n = 1884-1953, ~ 56% women). In addition, fracture diagnoses in 1980-2018 were searched for the national health care registers and 431 participants had at least one fracture. Food consumption was gathered with the 48-h dietary recall interviews and food frequency questionnaire in 1980-2007. In the present study, radial, tibial, and calcaneal bone traits, and fractures were examined relative to the long-term intake of SFA. No consistent associations were seen between bone outcomes and SFA intake that would have replicated in both women and men. The only evidence for differential distributions was seen in cortical density and cortical-to-total area ratio at the radial shaft, and speed of sound at the calcaneus, which were 0.1-0.4% higher in women in the lowest tertile of SFA intake compared with the highest tertile. In addition, among men, the odds ratio (OR) of fractures was greater in the second (OR 1.86, 95% confidence interval (CI) 1.03-3.33) and third tertile of SFA intake (OR 2.45, 95% CI 1.38-4.36) compared with the lowest tertile, independently of many risk factors of osteoporosis. In this observational study, we found no robust evidence of the associations of dietary long-term SFA intake with bone outcomes. Therefore, additional studies are needed to confirm the association of dietary SFA with bone health in humans.

Dynamic transcriptome changes during osteogenic differentiation of bone marrow-derived mesenchymal stem cells isolated from chicken

Osteoblasts are indispensable for skeletal growth and maintenance. Bone marrow-derived mesenchymal stem cells (BMSCs) are useful in studying osteogenesis. In this study, BMSCs isolated from White Leghorns were differentiated into osteoblasts in vitro. Cells induced for -1, 0, 1, 11, and 22 d were used for transcriptomic analyses using the HISAT2-Stringtie-DESeq2 pipeline. Weighted correlation network analysis was processed to investigate significant modules, including differentially expressed genes (DEGs), correlated with osteogenic differentiation. Gene ontology and pathway enrichment analyses of DEGs were performed to elucidate the mechanisms of osteoblast differentiation. A total of 534, 1,144, 1,077, and 337 DEGs were identified between cells induced for -1 and 0, 0 and 1, 1 and 11, and 11 and 22 d, respectively (|log2FC| > 1.0, FDR <0.05). DEGs were mainly enriched in pathways related to cell proliferation in the early stage of osteogenic differentiation and pathways, such as the TGF-β signaling pathway, in the middle and late stages of osteogenic differentiation. A protein–protein interaction network of the 87 DEGs in the MEturquoise module within top 5-%-degree value was built utilizing the STRING database. This study is the first to elucidate the transcriptomic changes in the osteogenic differentiation of BMSCs isolated from White Leghorns at different times. Our results provide insight into the dynamic transcriptome changes during BMSC differentiation into osteoblasts in chicken.

Obesity, Bone Loss, and Periodontitis: The Interlink

Obesity and periodontitis are both common health concerns that have given rise to considerable economic and societal burden worldwide. There are established negative relationships between bone metabolism and obesity, obesity and diabetes mellitus (DM), and DM and periodontitis, to name a few, with osteoporosis being considered a long-term complication of obesity. In the oral cavity, bone metabolic disorders primarily display as increased risks for periodontitis and alveolar bone loss. Obesity-driven alveolar bone loss and mandibular osteoporosis have been observed in animal models without inoculation of periodontopathogens. Clinical reports have also indicated a possible association between obesity and periodontitis. This review systematically summarizes the clinical periodontium changes, including alveolar bone loss in obese individuals. Relevant laboratory-based reports focusing on biological interlinks in obesity-associated bone remodeling via processes like hyperinflammation, immune dysregulation, and microbial dysbiosis, were reviewed. We also discuss the potential mechanism underlying obesity-enhanced alveolar bone loss from both the systemic and periodontal perspectives, focusing on delineating the practical considerations for managing periodontal disease in obese patients.

The Impact of Hempseed Consumption on Bone Parameters and Body Composition in Growing Female C57BL/6 Mice

Optimizing peak bone mass is critical to healthy aging. Beyond the established roles of dietary minerals and protein on bone integrity, fatty acids and polyphenols modify bone structure. This study investigated the effect of a diet containing hempseeds (HS), which are rich in polyunsaturated fatty acids and polyphenols, on bone mineral density, bone cell populations and body composition. Groups (n = 8 each) of female C57BL/6 mice were fed one of three diets (15% HS by weight; 5% HS; 0% HS (control)) from age 5 to 30 weeks. In vivo whole-body composition and bone mineral density and content were measured every 4 weeks using dual-energy X-ray absorptiometry. Ex vivo humeri cell populations in the epiphyseal plate region were determined by sectioning the bone longitudinally, mounting the sections on slides and staining with tartrate-resistant acid phosphatase and alkaline phosphatase stain to identify osteoclasts and osteoblasts, respectively. Mixed models with repeated measures across experimental weeks showed that neither body weight nor body weight gain across weeks differed among groups yet mice fed the 15% HS diet consumed significantly more food and more kilocalories per g body weight gained than those fed the 5% HS and control diets (p < 0.0001). Across weeks, fat mass was significantly higher in the 5% HS versus the control group (p = 0.02). At the end point, whole-body bone mineral content was significantly higher in the control compared to the 5% HS group (p = 0.02). Humeri from both HS groups displayed significantly lower osteoblast densities compared to the control group (p < 0.0001). No relationship was seen between osteoblast density and body composition measurements. These data invite closer examination of bone cell activity and microarchitecture to determine the effect of habitual HS consumption on bone integrity.

Comprehensive lipidomic analysis of the lipids extracted from freshwater fish bones and crustacean shells

A comprehensive lipidomic analysis of the lipids extracted from grass carp bones, black carp bones, shrimp shells, and crab shells was performed in this study. First, HPLC analysis revealed that the lipids extracted from shrimp and crab shells contained 60.65% and 77.25% of diacylglycerols, respectively. Second, GC-MS analysis identified 18 fatty acid species in the lipids extracted from fish bones and crustacean shells, in which polyunsaturated fatty acids (PUFAs) were highly enriched. PUFAs were present at 45.43% in the lipids extracted from shrimp shells. Notably, the lipids extracted from shrimp and crab shells contained a considerable amount of eicosapentaenoic acids and docosahexaenoic acids. Finally, multidimensional mass spectrometry-based shotgun lipidomics showed that various lipids including acetyl-L-carnitine, sphingomyelin (SM), lysophosphatidylcholine, and phosphatidylcholine (PC) were all identified in the lipid samples, but PC and SM were the most abundant. Specifically, the total content of PC in shrimp shells was as high as 6.145 mmol/g. More than 35 species of PC were found in all samples, which were more than other lipids. This study is expected to provide a scientific basis for the application of freshwater fish bones and crustacean shells in food, medicine, and other fields.

The Impact of Diet on Bone and Fracture Risk in Diabetes

PURPOSE OF REVIEW

The purpose of this review is to summarize the recently published scientific evidence on the effects of diet on diabetes and skeletal health.

RECENT FINDINGS

The impact of diet on overall health has been a growing topic of interest among researchers. An inappropriate eating habit is a relatively modified risk factor for diabetes in adults. Parallel with the significant increase in the incidence of diabetes mellitus worldwide, many studies have shown the benefits of lifestyle modifications, including diet and exercise for people with, or at risk of developing, diabetes. In the last years, accumulating evidence suggests that diabetes is a risk factor for bone fragility. As lifestyle intervention represents an effective option for diabetes management and treatment, there is potential for an effect on bone health. Healthy lifestyle is critical to prevent bone fragility. However, more studies are needed to fully understand the impact of diet and weight loss on fracture risk in diabetics.

Gender- and Age-Associated Differences in Bone Marrow Adipose Tissue and Bone Marrow Fat Unsaturation Throughout the Skeleton, Quantified Using Chemical Shift Encoding-Based Water-Fat MRI

Bone marrow adipose tissue (BMAT) is a dynamic tissue which is associated with osteoporosis, bone metastasis, and primary bone tumors. The aim of this study is to determine region-specific variations and age- and gender-specific differences in BMAT and BMAT composition in healthy subjects. In this cross-sectional study, we included 40 healthy subjects (26 male: mean age 49 years, range 22-75 years; 14 female: mean age 50 years, range 29-71) and determined the bone marrow signal fat fraction and bone marrow unsaturation in the spine (C3-L5), pelvis, femora, and tibiae using chemical shift encoding-based water-fat imaging (WFI) with multiple gradient echoes (mGRE). Regions of interest covered the individual vertebral bodies, pelvis and proximal epimetaphysis, diaphysis, and distal epimetaphysis of the femur and tibia. The spinal fat fraction increased from cervical to lumbar vertebral bodies (mean fat fraction ( ± SD or (IQR): cervical spine 0.37 ± 0.1; thoracic spine 0.41 ± 0.08. lumbar spine 0.46 ± 0.01; p < 0.001). The femoral fat fraction increased from proximal to distal (proximal 0.78 ± 0.09; diaphysis 0.86 (0.15); distal 0.93 ± 0.02; p < 0.001), while within the tibia the fat fraction decreased from proximal to distal (proximal 0.92 ± 0.01; diaphysis 0.91 (0.02); distal 0.90 ± 0.01; p < 0.001). In female subjects, age was associated with fat fraction in the spine, pelvis, and proximal femur (ρ = 0.88 p < 0.001; ρ = 0.87 p < 0.001; ρ = 0.63 p = 0.02; ρ = 0.74 p = 0.002, respectively), while in male subjects age was only associated with spinal fat fraction (ρ = 0.40 p = 0.04). Fat fraction and unsaturation were negatively associated within the spine (r = -0.40 p = 0.01), while in the extremities fat fraction and unsaturation were positively associated (distal femur: r = 0.42 p = 0.01; proximal tibia: r = 0.47, p = 0.002; distal tibia: r = 0.35 p = 0.03), both independent of age and gender. In conclusion, we confirm the distinct, age- and gender-dependent, distribution of BMAT throughout the human skeleton and we show that, contradicting previous animal studies, bone marrow unsaturation in human subjects is highest within the axial skeleton compared to the appendicular skeleton. Furthermore, we show that BMAT unsaturation was negatively correlated with BMAT within the spine, while in the appendicular skeleton, BMAT and BMAT unsaturation were positively associated.

Active Women Across the Lifespan: Nutritional Ingredients to Support Health and Wellness

Women are the largest consumers of dietary supplements. Dietary supplements can play a role in health and performance, particularly for women. Growing evidence and innovations support the unique physiological and nutrient timing needs for women. Despite the need for more nutrition and exercise-specific research in women, initial data and known physiological differences between sexes related to the brain, respiration, bone, and muscle support new product development and evidence-based education for active women regarding the use of dietary supplements. In this narrative review, we discuss hormonal and metabolic considerations with the potential to impact nutritional recommendations for active women. We propose four potential areas of opportunity for ingredients to help support the health and well-being of active women, including: (1) body composition, (2) energy/fatigue, (3) mental health, and (4) physical health.

Polyunsaturated Fatty Acids Level and Bone Mineral Density: A Two-Sample Mendelian Randomization Study

BACKGROUND

This Mendelian randomization (MR) study aimed to explore the causal relationship between polyunsaturated fatty acids (PUFAs) and bone mineral density (BMD).

METHODS

We conducted a two-sample MR analysis to figure out if there is any causal effect of PUFAs on BMD through the summary data from the genome-wide association study (GWAS). Relationships were evaluated through inverse variance weighted (IVW), MR-Egger, weighted median, and maximum likelihood methods. The MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) test was performed to detect the horizontal pleiotropy.

RESULTS

Our findings revealed that omega-6 fatty acids were negatively related to the TB-BMD (beta-estimate: -0.0515; 95% confidence interval [CI]: -0.0911 to -0.0119; standard error [SE]: 0.0201; p-value: 0.0106). The reverse direction MR analysis showed that TB-BMD was linked to the omega-6 FAs (beta-estimate: -0.0699; 95% CI: -0.1304 to -0.0095; SE: 0.0308; p-value: 0.0265). No statistically significant correlations between PUFAs and BMD were observed after adjusting the interactions between metabolites.

CONCLUSION

This two-sample MR analyses produced strong and new genomic evidence that there was a causal relationship between omega-6 FAs and BMD. Further investigations are still required to elucidate the potential mechanism.

Adiponectin, May Be a Potential Protective Factor for Obesity-Related Osteoarthritis

Osteoarthritis (OA) is the most common joint disease in elderly individuals and seriously affects quality of life. OA has often been thought to be caused by body weight load, but studies have increasingly shown that OA is an inflammation-mediated metabolic disease. The current existing evidence suggests that OA is associated with obesity-related chronic inflammation as well as abnormal lipid metabolism in obesity, such as fatty acids (FA) and triglycerides. Adiponectin, a cytokine secreted by adipose tissue, can affect the progression of OA by regulating obesity-related inflammatory factors. However, the specific molecular mechanism has not been fully elucidated. According to previous research, adiponectin can promote the metabolism of FA and triglycerides, which indicates that it is a potential protective factor for OA through many mechanisms. This article aims to review the mechanisms of chronic inflammation, FA and triglycerides in OA, as well as the potential mechanisms of adiponectin in regulating chronic inflammation and promoting FA and triglyceride metabolism. Therefore, adiponectin may have a protective effect on obesity-related OA, which could provide new insight into adiponectin and the related mechanisms in OA.

Nutrition, Physical Activity, and Dietary Supplementation to Prevent Bone Mineral Density Loss: A Food Pyramid

Bone is a nutritionally modulated tissue. Given this background, aim of this review is to evaluate the latest data regarding ideal dietary approach in order to reduce bone mineral density loss and to construct a food pyramid that allows osteopenia/osteoporosis patients to easily figure out what to eat. The pyramid shows that carbohydrates should be consumed every day (3 portions of whole grains), together with fruits and vegetables (5 portions; orange-colored fruits and vegetables and green leafy vegetables are to be preferred), light yogurt (125 mL), skim milk (200 mL,) extra virgin olive oil (almost 20 mg/day), and calcium water (almost 1 l/day); weekly portions should include fish (4 portions), white meat (3 portions), legumes (2 portions), eggs (2 portions), cheeses (2 portions), and red or processed meats (once/week). At the top of the pyramid, there are two pennants: one green means that osteopenia/osteoporosis subjects need some personalized supplementation (if daily requirements cannot be satisfied through diet, calcium, vitamin D, boron, omega 3, and isoflavones supplementation could be an effective strategy with a great benefit/cost ratio), and one red means that there are some foods that are banned (salt, sugar, inorganic phosphate additives). Finally, three to four times per week of 30-40 min of aerobic and resistance exercises must be performed.

Non-polar lipid from greenshell mussel (Perna canaliculus) inhibits osteoclast differentiation

The osteoclast-dependent bone resorption process is a crucial part of the bone regulatory system. The excessive function of osteoclasts can cause diseases of bone, joint, and other tissues such as osteoporosis and osteoarthritis. Greenshell mussel oil (GSM), a good source of long chain omega-3 polyunsaturated fatty acids (LCn-3PUFAs), was fractionated into total lipid, polar lipid, and non-polar lipid components and their anti-osteoclastogenic activity tested in RAW 264.7 cell cultures. Osteoclast differentiation process was achieved after 5 days of incubation with RANKL in 24-well culture plates. Introducing the non-polar lipid fraction into the culture caused a lack of cell differentiation, and a reduction in tartrate-resistant acid phosphatase (TRAP) activity and TRAP cell numbers in a dose-dependent manner (50% reduction at the concentration of 20 μg/mL, p < 0.001). Moreover, actin ring formation was significantly diminished by non-polar lipids at 10-20 μg/mL. The bone digestive enzymes released by osteoclasts into the pit formation were also compromised by downregulating gene expression of cathepsin K, carbonic anhydrase II (CA II), matrix metalloproteinase 9 (MMP-9), and nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1). This study revealed that the non-polar lipid fraction of GSM oil contains bioactive substances which possess potent anti-osteoclastogenic activity.

MUFAs in High-Fat Diets Protect against Obesity-Induced Bias of Hematopoietic Cell Lineages

SCOPE

The role of dietary fatty acids in the generation of bone marrow (BM) immune cells and their trafficking to extramedullary compartments in the obesity is not yet fully understood.

METHODS AND RESULTS

C57BL/6J mice are randomly assigned to isocaloric high-fat diets (HFDs) formulate with dietary fats rich in saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) or MUFAs fortified with eicosapentaenoic and docosahexaenoic acids for 20 weeks, followed by profiling of the obese metabolic phenotype and immunophenotypic features of immune cells in blood, spleen, and BM. All HFDs induce an obese phenotype, but it becomes largely less disruptive after the HFDs are enriched in MUFAs, which also induce signs of granulopoiesis and an expansion of long-term hematopoietic stem and granulocyte-macrophage progenitor cells in BM. In contrast, a HFD enriched in SFAs disturbs the fitness of medullary lymphocytes and promotes monopoiesis in favor of pro-inflammatory activated subsets.

CONCLUSION

The reshaping of the fatty acid pools with MUFAs from the diet serves to manipulate the generation and trafficking of immune cells that are biased during obesity. These findings reveal a novel strategy by which dietary MUFAs may be instrumental in combating HFD-induced dysfunctional immune systems.

Pro-Osteogenic Properties of Violina pumpkin (Cucurbita moschata) Leaf Extracts: Data from In Vitro Human Primary Cell Cultures

Traditional medicines rely mainly on use of plant extracts to mitigate or treat a wide range of disorders, including those that affect skeletal homeostasis. In this study, we investigated for the first time the potential pro-osteogenic effects of hexane, acetone and methanol extracts of the leaves of Cucurbita moschata, a very popular pumpkin cultivar in Western countries. We found that in Cucurbita moschata leaves, there are acetone-extractable substances—in particular, fatty acids such as 13-OH-9Z,11E,15E-octadecatrienoic acid (PU-13OH-FA), which is capable of both stimulating the function of human primary osteoblasts, which are responsible for bone formation, and inhibiting the differentiation of human osteoclasts, which are responsible for bone resorption. This dual effect was monitored by analyzing Runx2 expression, deposition of mineralized matrix, ALP activity, TRAP and actin ring staining respectively. This study suggests that bioactive chemicals from Cucurbita moschata leaves are potentially suitable as therapeutics for managing metabolic bone disorders such as osteoporosis and rheumatoid arthritis, and promoting tissue healing and functional recovery after bone fractures. The data we obtained increase knowledge on the biological activities of Cucurbita moschata, and in particular underline the potential benefits of consuming leaves which are a part of the plant currently little considered in the Western world.

Marine n-3 Polyunsaturated Fatty Acids and Bone Mineral Density in Kidney Transplant Recipients: A Randomized, Placebo-Controlled Trial

Kidney transplant recipients are at high risk of progressive bone loss and low-energy fractures in the years following transplantation. Marine n-3 polyunsaturated fatty acids (n-3 PUFA) supplementation may have beneficial effects on bone strength. The Omega-3 fatty acids in Renal Transplantation (ORENTRA) trial was an investigator initiated, randomized, placebo-controlled trial investigating the effects of marine n-3 PUFA supplementation after kidney transplantation. Effects of supplementation on bone mineral density (BMD) and calcium metabolism were pre-defined secondary endpoints. Adult kidney transplant recipients (n = 132) were randomized to 2.6 g marine n-3 PUFA supplement or olive oil (control) from 8 to 52 weeks post-transplant. Dual energy X-ray absorptiometry was performed to assess changes in bone mineral density of hip, spine, and forearm, as well as trabecular bone score (TBS) of the lumbar spine. Student's t test was used to assess between-group differences. There were no differences in ΔBMD between the two groups (intervention vs. control) at lumbar spine (-0.020 ± 0.08 vs. -0.007 ± 0.07 g/cm², p = 0.34), total hip (0.001 ± 0.03 vs. -0.005 ± 0.04, p = 0.38), or other skeletal sites in the intention-to-treat analyses. There was no difference in the change in TBS score (0.001 ± 0.096 vs. 0.009 ± 0.102, p = 0.62). Finally, no effect on biochemical parameters of mineral metabolism was seen. Results were similar when analyzed per protocol. In conclusion, we found no significant effect of 44 weeks of supplementation with 2.6 g of marine n-3 PUFA on BMD in kidney transplant recipients.

Bone-Adipose Tissue Crosstalk: Role of Adipose Tissue Derived Extracellular Vesicles in Bone Diseases

Bone is a metabolically active organ that undergoes constant remodeling throughout life. A failure of this process leads to pathological destructive bone diseases such as osteoporosis, rheumatoid arthritis, and osteoarthritis. Studies of the interplay between adipose tissue and bone system, have revealed that adipose tissue disorders (e.g. obesity) strongly influence the development of bone diseases. Adipokines secreted by adipose tissue play important roles in the crosstalk between bone and adipose tissue. Recently, extracellular vesicles (EVs) have been identified as a novel method of communication between different organs and have attracted increased attention in the field of bone remodeling process. Adipokines carried by EVs are known to play pivotal roles in bone remodeling processes including osteogenesis and osteoclastogenesis. In this review, we highlighted the role of adipose tissue derived EVs (EVs-AT) in the context of bone remodeling events and focused on the characteristics of EVs-AT and their components in the regulation of bone diseases. Moreover, we introduced the intriguing therapeutic application of EVs-AT in different pathological destructive bone diseases and proposed future directions for research on EVs-AT in bone diseases.

The Role of Osteoclast Energy Metabolism in the Occurrence and Development of Osteoporosis

In recent decades, the mechanism underlying bone metabolic disorders based on energy metabolism has been heavily researched. Bone resorption by osteoclasts plays an important role in the occurrence and development of osteoporosis. However, the mechanism underlying the osteoclast energy metabolism disorder that interferes with bone homeostasis has not been determined. Bone resorption by osteoclasts is a process that consumes large amounts of adenosine triphosphate (ATP) produced by glycolysis and oxidative phosphorylation. In addition to glucose, fatty acids and amino acids can also be used as substrates to produce energy through oxidative phosphorylation. In this review, we summarize and analyze the energy-based phenotypic changes, epigenetic regulation, and coupling with systemic energy metabolism of osteoclasts during the development and progression of osteoporosis. At the same time, we propose a hypothesis, the compensatory recovery mechanism (involving the balance between osteoclast survival and functional activation), which may provide a new approach for the treatment of osteoporosis.

Synovial Fluid Fatty Acid Profiles Are Differently Altered by Inflammatory Joint Pathologies in the Shoulder and Knee Joints

Anomalies of fatty acid (FA) metabolism characterize osteoarthritis (OA) and rheumatoid arthritis (RA) in the knee joint. No previous study has investigated the synovial fluid (SF) FA manifestations in these aging-related inflammatory diseases in the shoulder. The present experiment compared the FA alterations between the shoulder and knee joints in patients with end-stage OA or end-stage RA. SF samples were collected during glenohumeral or knee joint surgery from trauma controls and from OA and RA patients (n = 42). The FA composition of SF total lipids was analyzed by gas chromatography with flame ionization and mass spectrometric detection and compared across cohorts. The FA signatures of trauma controls were mostly uniform in both anatomical locations. RA shoulders were characterized by elevated percentages of 20:4n-6 and 22:6n-3 and with reduced proportions of 18:1n-9. The FA profiles of OA and RA knees were relatively uniform and displayed lower proportions of 18:2n-6, 22:6n-3 and total n-6 polyunsaturated FAs (PUFAs). The results indicate location- and disease-dependent differences in the SF FA composition. These alterations in FA profiles and their potential implications for the production of PUFA-derived lipid mediators may affect joint lubrication, synovial inflammation and pannus formation as well as cartilage and bone degradation and contribute to the pathogeneses of inflammatory joint diseases.

Fatty Acids and Oxylipins in Osteoarthritis and Rheumatoid Arthritis-a Complex Field with Significant Potential for Future Treatments

Purpose of Review

Osteoarthritis (OA) and rheumatoid arthritis (RA) are characterized by abnormal lipid metabolism manifested as altered fatty acid (FA) profiles of synovial fluid and tissues and in the way dietary FA supplements can influence the symptoms of especially RA. In addition to classic eicosanoids, the potential roles of polyunsaturated FA (PUFA)-derived specialized pro-resolving lipid mediators (SPM) have become the focus of intensive research. Here, we summarize the current state of knowledge of the roles of FA and oxylipins in the degradation or protection of synovial joints.

Recent Findings

There exists discordance between the large body of literature from cell culture and animal experiments on the adverse and beneficial effects of individual FA and the lack of effective treatments for joint destruction in OA and RA patients. Saturated 16:0 and 18:0 induce mostly deleterious effects, while long-chain n-3 PUFA, especially 20:5n-3, have positive influence on joint health. The situation can be more complex for n-6 PUFA, such as 18:2n-6, 20:4n-6, and its derivative prostaglandin E₂, with a combination of potentially adverse and beneficial effects. SPM analogs have future potential as analgesics for arthritic pain.

Summary

Alterations in FA profiles and their potential implications in SPM production may affect joint lubrication, synovial inflammation, pannus formation, as well as cartilage and bone degradation and contribute to the pathogeneses of inflammatory joint diseases. Further research directions include high-quality randomized controlled trials on dietary FA supplements and investigations on the significance of lipid composition of microvesicle membrane and cargo in joint diseases.

Plasma Fatty Acids and Quantitative Ultrasound, DXA and pQCT Derived Parameters in Postmenopausal Spanish Women

Different factors may contribute to the development of osteopenia or osteoporosis. Fatty acids are key nutrients for health, and a number of studies have reported an association between bone mineral density (BMD) and fatty acid intake. We aimed to investigate the relationships between serum levels of different fatty acids and bone parameters determined by quantitative bone ultrasound (QUS), peripheral quantitative computed tomography (pQCT), and dual-energy X-ray absorptiometry (DXA) in a sample of Spanish postmenopausal women. We enrolled a total of 301 postmenopausal women (median age 59 years; interquartile range (IQR) 7) in this study. All participants underwent full densitometric screening, including calcaneal quantitative ultrasound (QUS), peripheral quantitative computed tomography (pQCT), and dual-energy X-ray absorptiometry (DXA), as well as plasma fatty acid measurement. After adjustment for potential confounders, plasma n-3 polyunsaturated fatty acid (PUFA) levels correlated with BMD in the spine (r = 0.150; p = 0.014) and femoral neck (r = 0.143; p = 0.019). By multiple linear regression, an independent statistically significant positive relationship was observed between BMD in the spine and BMI (β = 0.288; p = 0.001) as well as total plasma n-3 PUFAs (β = 0.155; p = 0.009). The plasma n-3 PUFA level was also a significant and positive predictor of BMD at the femoral neck (β = 0.146; p = 0.009). Independent risk factors for low BMD (T-score ≤ 1) were determined by logistic regression analysis, and a relatively high level of plasma n-3 PUFAs (OR = 0.751; 95% CI 0.587-0.960, p = 0.022) was identified as a protective factor against low bone mass. In this single-center sample of Spanish postmenopausal women, we reported a significant positive and statistically independent association between BMD and plasma levels of n-3 PUFAs.

Identification of co-expression network correlated with different periods of adipogenic and osteogenic differentiation of BMSCs by weighted gene co-expression network analysis (WGCNA)

Background

The differentiation of bone marrow mesenchymal stem cells is a complex and dynamic process. The gene expression pattern and mechanism of different periods of adipogenic and osteogenic differentiation remain unclear. Additionally, the interaction between these two lineage determination requires further exploration.

Results

Five modules that were most significantly associated with osteogenic or adipogenic differentiation of BMSCs were selected for further investigation. Biological terms (e.g. ribosome biogenesis, TNF-α signalling pathway, glucose import and fatty acid metabolism) along with hub transcription factors (e.g. PPARG and YY1) and hub miRNAs (e.g. hsa-mir-26b-5p) were enriched in different modules. The expression pattern of 6 hub genes, ADIPOQ, FABP4, SLC7A5, SELPLG, BIRC3, and KLHL30 was validated by RT-qPCR. Finally, cell staining experiments extended the findings of bioinformatics analysis.

Conclusion

This study identified the key genes, biological functions, and regulators of each time point of adipogenic and osteogenic differentiation of BMSCs and provided novel evidence and ideas for further research on the differentiation of BMSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07584-4.

Capsaicin on stem cell proliferation and fate determination - a novel perspective

Capsaicin (CAP), a member of the vanilloid family, is the main active component of chili peppers, which has been widely explored for its various pharmacological effects and influence on cell physiology, such as axonal growth and apoptosis of tumor cells. In particular, CAP plays a crucial role in determining the proliferation and fate specification of stem cells by modulating a variety of signaling pathways, such as PPARγ, C/EBPα and Notch signaling. Since CAP-mediated processes are complex and multifactorial, we hope to achieve a better understanding of these processes and their implications in clinical applications. This review aims to shed light on the influences and mechanisms of CAP on the actions of various stem cells in adults and discusses the role of CAP in the different process of stem cell behaviors, including proliferation and differentiation. Our purpose is to provide certain prospects for the application of CAP and stem cell therapy in treating diseases.

Influence of Micronutrient Intake, Sociodemographic, and Behavioral Factors on Periodontal Status of Adults Assisted by a Public Health Care System in Brazil: A Cross-Sectional Multivariate Analysis

The lack of access to a balanced diet, rich in vitamins and minerals, can predispose people to inflammatory diseases such as obesity, diabetes mellitus, and periodontitis. We aimed to evaluate the relationship between micronutrient intake, sociodemographic behavioral characteristics, and periodontal health in adults assisted by a public health care system. Participants (n = 450) answered a food frequency questionnaire and were submitted to anthropometric and oral clinical examinations. Principal component analysis was used to summarize the number of components emerging from 17-micronutrient intake. Subsequently, cluster analysis was employed. The prevalence of at least one periodontal pocket ≥ 4 mm was 67.4%. Three clusters were identified according to periodontal status. Cluster 1 "poor periodontal status" was characterized by older individuals (n = 202; 85% females) with poor periodontal status, lower education level, mainly smokers with non-transmissible chronic diseases (NTCD), with lower energy, omega-3, fiber, Zn, K, Cu, and vitamin C intake. Cluster 3 "healthy periodontal status" included younger individuals (n = 54) with the healthiest periodontal status, a higher education level, without NTCD, and with higher energy, omega-3, fiber, Zn, calcium, retinol, and riboflavin intake. Cluster 2 was labeled as "intermediate periodontal status". Micronutrient ingestion was associated with periodontal status and may be considered in health promotion actions for low-income populations.