Retinol-binding protein 4 is expressed in chondrocytes of developing mouse long bones: implications for a local role in formation of the secondary ossification center

Sex-specific association of low-renin hypertension with metabolic and musculoskeletal health in Korean older adults

Introduction

Low-renin hypertension (LRH) accounts for approximately one-third of patients with hypertension and are more prevalent in women and the older adult population. Previous study has found a link between the renin-angiotensin-aldosterone system (RAAS) and sex hormones. However, there are insufficient data on the relationship between LRH and metabolic or musculoskeletal outcomes in older adults.

Methods and materials

Among the 343 participants from a population-based cohort study conducted between May 2018 and August 2019, a total of 256 (86 men older than 50 years and 170 postmenopausal women) were included. The presence of LRH was defined as plasma renin activity (PRA) <1 ng/mL/h and systolic blood pressure (BP) ≥130 or diastolic BP ≥80 mmHg based on the 2017 ACC/AHA guidelines. Individuals with missing data, and those who had used medications that could affect PRA within the past six months were excluded. Bone mineral density (BMD), trabecular bone score (TBS), and appendicular lean mass (ALM) index were assessed using dual-energy X-ray absorptiometry; degraded TBS was defined as partially degraded to degraded levels (≤1.350). Muscle function was assessed according to the Asian Working Group for Sarcopenia guidelines. PRA was measured using radioimmunoassay.

Results

The median age was 66 [61-72] years, and the body mass index (BMI) was 24.7 [23.0-26.4] kg/m2. Individuals with LRH, accounting for 34.8%, had lower diabetes mellitus; more dyslipidemia; and poorer muscle function, BMD, and TBS than those in the non-LRH group. In addition, PRA was positively correlated with C-peptide, HOMA-IR, TBS, and ALM index. After adjusting for covariates including age and BMI, LRH was negatively associated with femur neck T-score (adjusted β = -0.30, 95% CI [-0.55 to -0.05], p = 0.021) and the presence of LRH was significantly associated with degraded TBS in women (adjusted odds ratio = 3.00, 95% CI [1.36-6.58], p = 0.006).

Conclusion

Our findings suggest that LRH can influence clinical features and metabolic risk in older adults. Notably, LRH in postmenopausal women was linked to lower femur neck T-scores and degraded TBS, indicating sex-specific effects of LRH on bone health. Larger prospective studies are required to elucidate how changes in the RAAS affect metabolic and musculoskeletal outcomes in older adults.

Novel Adipokines and Their Role in Bone Metabolism: A Narrative Review

The growing burden of obesity and osteoporosis is a major public health concern. Emerging evidence of the role of adipokines on bone metabolism has led to the discovery of novel adipokines over the last decade. Obesity is recognized as a state of adipose tissue inflammation that adversely affects bone health. Adipokines secreted from white adipose tissue (WAT) and bone marrow adipose tissue (BMAT) exerts endocrine and paracrine effects on the survival and function of osteoblasts and osteoclasts. An increase in marrow fat is implicated in osteoporosis and, hence, it is crucial to understand the complex interplay between adipocytes and bone. The objective of this review is to summarize recent advances in our understanding of the role of different adipokines on bone metabolism.

METHODS

This is a comprehensive review of the literature available in PubMED and Cochrane databases, with an emphasis on the last five years using the keywords.

RESULTS

Leptin has shown some positive effects on bone metabolism; in contrast, both adiponectin and chemerin have consistently shown a negative association with BMD. No significant association was found between resistin and BMD. Novel adipokines such as visfatin, LCN-2, Nesfatin-1, RBP-4, apelin, and vaspin have shown bone-protective and osteoanabolic properties that could be translated into therapeutic targets.

CONCLUSION

New evidence suggests the potential role of novel adipokines as biomarkers to predict osteoporosis risk, and as therapeutic targets for the treatment of osteoporosis.

The prognostic value of retinol binding protein in geriatric hip fractures after surgeries: A propensity score matching and 1-year follow-up study

BACKGROUND

We aimed to explore the predictive value of retinol binding protein (RBP) for outcomes of hip fractures.

METHODS

Patients with hip fractures who underwent hip surgeries between December 2017 and February 2021 and met the inclusion criteria were analyzed. Propensity score matching was used to reduce the bias of co-factors and ROC curves based on matched populations were created to determine the optimal cutoff point of RBP. The outcomes between patients with low levels of RBP and high levels of RBP were compared.

RESULTS

Four hundred eighty patients were enrolled in this study and 69 patients died within one year. After a 1:1 PSM, patients with more than 1-year survival had significantly higher RBP (p = 0.013) than those who died within one year, as well as patients divided by 6-months survival (p = 0.012). Logistics analysis showed that low RBP may be an independent risk factor for 3-month survival, 6-month survival, 1-year survival, and 3-month free walking ability.

CONCLUSION

RBP may be associated with the survival and 3-month walking abilities of patients with hip fractures.

Retinol-binding protein 4 in obesity and metabolic dysfunctions

Excessive increased adipose tissue mass in obesity is associated with numerous co-morbid disorders including increased risk of type 2 diabetes, fatty liver disease, hypertension, dyslipidemia, cardiovascular diseases, dementia, airway disease and some cancers. The causal mechanisms explaining these associations are not fully understood. Adipose tissue is an active endocrine organ that secretes many adipokines, cytokines and releases metabolites. These biomolecules referred to as adipocytokines play a significant role in the regulation of whole-body energy homeostasis and metabolism by influencing and altering target tissues function. Understanding the mechanisms of adipocytokine actions represents a hot topic in obesity research. Among several secreted bioactive signalling molecules from adipose tissue and liver, retinol-binding protein 4 (RBP4) has been associated with systemic insulin resistance, dyslipidemia, type 2 diabetes and other metabolic diseases. Here, we aim to review and discuss the current knowledge on RBP4 with a focus on its role in the pathogenesis of obesity comorbid diseases.

Plasma Proteomic Analysis in Morquio A Disease

Mucopolysaccharidosis type IVA (MPS IVA) is a lysosomal disease caused by mutations in the gene encoding the enzymeN-acetylgalactosamine-6-sulfate sulfatase (GALNS), and is characterized by systemic skeletal dysplasia due to excessive storage of keratan sulfate (KS) and chondroitin-6-sulfate in chondrocytes. Although improvements in the activity of daily living and endurance tests have been achieved with enzyme replacement therapy (ERT) with recombinant human GALNS, recovery of bone lesions and bone growth in MPS IVA has not been demonstrated to date. Moreover, no correlation has been described between therapeutic efficacy and urine levels of KS, which accumulates in MPS IVA patients. The objective of this study was to assess the validity of potential biomarkers proposed by other authors and to identify new biomarkers. To identify candidate biomarkers of this disease, we analyzed plasma samples from healthy controls (n=6) and from untreated (n=8) and ERT-treated (n=5, sampled before and after treatment) MPS IVA patients using both qualitative and quantitative proteomics analyses. The qualitative proteomics approach analyzed the proteomic profile of the different study groups. In the quantitative analysis, we identified/quantified 215 proteins after comparing healthy control untreated, ERT-treated MPSIVA patients. We selected a group of proteins that were dysregulated in MPS IVA patients. We identified four potential protein biomarkers, all of which may influence bone and cartilage metabolism: fetuin-A, vitronectin, alpha-1antitrypsin, and clusterin. Further studies of cartilage and bone samples from MPS IVA patients will be required to verify the validity of these proteins as potential biomarkers of MPS IVA.

RNA-seq reveals downregulated osteochondral genes potentially related to tibia bacterial chondronecrosis with osteomyelitis in broilers

Background

Bacterial chondronecrosis with osteomyelitis (BCO) develops in the growth plate (GP) of the proximal femur and tibia and is initiated by damage to the less mineralized chondrocytes followed by colonization of opportunistic bacteria. This condition affects approximately 1% of all birds housed, being considered one of the major causes of lameness in fast growing broilers. Although several studies have been previously performed aiming to understand its pathogenesis, the molecular mechanisms involved with BCO remains to be elucidated. Therefore, this study aimed to generate a profile of global differential gene expression involved with BCO in the tibia of commercial broilers, through RNA sequencing analysis to identity genes and molecular pathways involved with BCO in chickens.

Results

Our data showed 192 differentially expressed (DE) genes: 63 upregulated and 129 downregulated in the GP of the tibia proximal epiphysis of BCO-affected broilers. Using all DE genes, six Biological Processes (BP) were associated with bone development (connective tissue development, cartilage development, skeletal system development, organ morphogenesis, system development and skeletal system morphogenesis). The analyses of the upregulated genes did not indicate any significant BP (FDR < 0.05). However, with the downregulated genes, the same BP were identified when using all DE genes in the analysis, with a total of 26 coding genes explaining BCO in the tibia: ACAN, ALDH1A2, CDH7, CHAD, CHADL, COL11A1, COMP, CSGALNACT1, CYR61, FRZB, GAL3ST1, HAPLN1, IHH, KIF26B, LECT1, LPPR1, PDE6B, RBP4A, SERINC5, SFRP1, SOX8, SOX9, TENM2, THBS1, UCHL1 and WFIKKN2. In addition, seven transcription factors were also associated to BCO: NFATC2, MAFB, HIF1A-ARNT, EWSR1-FLI1, NFIC, TCF3 and NF-KAPPAB.

Conclusions

Our data show that osteochondral downregulated genes are potential molecular causes of BCO in broilers, and the bacterial process seems to be, in fact, a secondary condition. Sixteen genes responsible for bone and cartilage formation were downregulated in BCO-affected broilers being strong candidate genes to trigger this disorder.

Progenitor Cells Activated by Platelet Lysate in Human Articular Cartilage as a Tool for Future Cartilage Engineering and Reparative Strategies

Regenerative strategies for human articular cartilage are still challenging despite the presence of resident progenitor cell population. Today, many efforts in the field of regenerative medicine focus on the use of platelet derivatives due to their ability to reactivate endogenous mechanisms supporting tissue repair. While their use in orthopedics continues, mechanisms of action and efficacy need further characterization. We describe that the platelet lysate (PL) is able to activate chondro-progenitor cells in a terminally differentiated cartilage tissue. Primary cultures of human articular chondrocytes (ACs) and cartilage explants were set up from donor hip joint biopsies and were treated in vitro with PL. PL recruited a chondro-progenitors (CPCs)-enriched population from ex vivo cartilage culture, that showed high proliferation rate, clonogenicity and nestin expression. CPCs were positive for in vitro tri-lineage differentiation and formed hyaline cartilage-like tissue in vivo without hypertrophic fate. Moreover, the secretory profile of CPCs was analyzed, together with their migratory capabilities. Some CPC-features were also induced in PL-treated ACs compared to fetal bovine serum (FBS)-control ACs. PL treatment of human articular cartilage activates a stem cell niche responsive to injury. These facts can improve the PL therapeutic efficacy in cartilage applications.

Circulating Retinol-Binding Protein 4 as a Possible Biomarker of Treatment Response for Ankylosing Spondylitis: An Array-Based Comparative Study

Objective

To explore proteins associated with ankylosing spondylitis (AS) and to investigate potential proteins that may predict treatment response of adalimumab (ADA) in AS patients.

Methods

In the discovery cohort, 39 AS patients and 20 healthy controls (HCs) were included, and 16 AS patients received ADA treatment for 24 weeks after included. In the validation cohort, 43 AS patients and 39 HCs were enrolled, and all 43 patients received ADA treatment after enrollment. Blood samples and clinical information were collected from two cohorts at baseline from all participants and week 24 from patients received ADA treatment. A human antibody array containing 1,000 proteins was used in the discovery phase, and Elisa kits were used for protein validation.

Results

Compared with HCs, we identified 53 differentially expressed proteins (DEPs) in AS patients. Bioinformatics analysis revealed they were mostly enriched in coagulation function-related pathways, acute response signaling, and LXR/RXR activation. Bone metabolism pathways were also associated. Comparison between samples of pre- and post-ADA treatment revealed 42 DEPs. They were mostly associated with bone metabolism and inflammation response pathways. Significant enrichment was also found in LXR/RXR activation but not the coagulation function-related pathways. Upstream regulator analysis suggested that most regulators also significantly functioned under usage of ADA. Precisely, seven proteins were abnormally expressed in AS and restored after ADA treatment. Retinol-binding protein 4 (RBP4), one of the seven proteins, was validated that its baseline levels were inversely correlated with improvements in Ankylosing Spondylitis Disease Activity Score-C-reactive protein (ASDAS-CRP). Likewise, percentage changes in RBP4 levels were inversely correlated with changes in ASDAS-CRP score.

Conclusion

A dysregulated serum protein profile existed in AS. ADA exerted a considerable but not entire alteration toward the dysregulation. RBP4 could be a biomarker for predicting and monitoring ADA treatment response.

Screening for reproductive biomarkers in Bactrian camel via iTRAQ analysis of proteomes

Bactrian camel is an ancient and precious species of livestock; that is, unique resources exist in the desert and have important economic and scientific value. In recent years, the number of Bactrian camels has declined sharply. Due to its long reproductive cycle and seasonal oestrus, the mechanism of oestrus is unknown. To identify candidate biomarkers of reproduction, we performed a comprehensive proteomic analysis of serum from Bactrian camel in oestrus and non-oestrus, using isobaric tags for relative and absolute quantitation (iTRAQ) coupled with tandem mass spectrometry. We identified 359 proteins, of which 32 were differentially expressed: 11 were up-regulated and 21 were down-regulated in samples from camels in oestrus. We validated the differential expression of a subset of these proteins using qPCR and Western blot. Gene ontology annotation identified that the differentially expressed proteins function in cellular processes, metabolic processes and immune system processes. Notably, five of the differentially expressed proteins, PCGF5, histone H1.2, RBP4, FOLR1 and ANTXR2, are involved in reproductive regulatory processes in other animals. KEGG enrichment analysis demonstrated significant enrichment in several cardiac-related pathways, such as 'dilated cardiomyopathy', 'hypertrophic cardiomyopathy', 'cardiac muscle contraction' and 'adrenergic signalling in cardiomyopathy'. Our results suggest that candidate biomarker (PCGF5, histone H1.2, RBP4, FOLR1 and ANTXR2) discovery can aid in understanding reproduction in Bactrian camels. We conclude that the profiling of serum proteomes, followed by the measurement of selected proteins using more targeted methods, offers a promising approach for studying mechanisms of oestrus.

Involvement of RBP4 in all‑trans retinoic acid induced cleft palate

The current study was designed to elucidate the mechanism of retinol binding protein 4 (RBP4) in cleft palate induced by all‑trans retinoic acid (atRA). To establish a cleft palate model in C57BL/6J mice, pregnant mice were administered atRA (100 mg/kg) by gavage at the tenth embryonic stage (E10.0). Control groups were given the equivalent volume of corn oil. Pregnant mice were dissected at E12.5, E13.5 and E14.5 to obtain the embryonic palates. The expression levels of RBP4 in the embryonic palatal mesenchyme (EPM) were determined by immunohistochemistry, reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting. Human embryonic palatal mesenchymal cells were exposed to atRA to detect the variation in RBP4 induced by atRA in vitro. Small interfering RNA was used to suppress the expression of RBP4, and a plasmid overexpressing RBP4 was used to examine upregulated expression. The cell counting kit‑8 assay was used to evaluate the effect of RBP4 on cell proliferation. The expression levels of p27 and cyclin D1 were determined by RT‑qPCR and western blotting, while the expression levels of extracellular signal‑related kinase (ERK) 1/2 and protein kinase B (AKT) were assessed by western blotting. At E14.5, RBP4 was strongly expressed in the EPM, while it was downregulated following atRA treatment, which induced cleft palate in vivo. In vitro experiments indicated that atRA suppressed the expression of RBP4 and altered the expression of p27 and cyclin D1 to cause growth inhibition. Knockdown of RBP4 resulted in decreased expression of cyclin D1 and increased p27, and suppressed proliferation. Overexpression of RBP4 reversed the inhibitory effect of atRA and promoted proliferation via the ERK1/2 and AKT signaling pathways. These results suggested that RBP4 was involved in cleft palate induced by atRA and it can be suppressed by atRA to cause growth inhibition in the embryonic palate.

The Histochem Cell Biol conspectus: the year 2013 in review

Herein, we provide a brief synopsis of all manuscripts published in Histochem Cell Biol in the year 2013. For ease of reference, we have divided the manuscripts into the following categories: Advances in Methodologies; Molecules in Health and Disease; Organelles, Subcellular Structures and Compartments; Golgi Apparatus; Intermediate Filaments and Cytoskeleton; Connective Tissue and Extracellular Matrix; Autophagy; Stem Cells; Musculoskeletal System; Respiratory and Cardiovascular Systems; Gastrointestinal Tract; Central Nervous System; Peripheral Nervous System; Excretory Glands; Kidney and Urinary Bladder; and Male and Female Reproductive Systems. We hope that the readership will find this annual journal synopsis of value and serve as a quick, categorized reference guide for “state-of-the-art” manuscripts in the areas of histochemistry, immunohistochemistry, and cell biology.

The Histochemistry and Cell Biology compendium: a review of 2012

The year 2012 was another exciting year for Histochemistry and Cell Biology. Innovations in immunohistochemical techniques and microscopy-based imaging have provided the means for advances in the field of cell biology. Over 130 manuscripts were published in the journal during 2012, representing methodological advancements, pathobiology of disease, and cell and tissue biology. This annual review of the manuscripts published in the previous year in Histochemistry and Cell Biology serves as an abbreviated reference for the readership to quickly peruse and discern trends in the field over the past year. The review has been broadly divided into multiple sections encompassing topics such as method advancements, subcellular components, extracellular matrix, and organ systems. We hope that the creation of this subdivision will serve to guide the reader to a specific topic of interest, while simultaneously providing a concise and easily accessible encapsulation of other topics in the broad area of Histochemistry and Cell Biology.