High dietary salt intake correlates with modulated Th17-Treg cell balance resulting in enhanced bone loss and impaired bone-microarchitecture in male mice

Proteomic Biomarkers Associated with Low Bone Mineral Density: A Systematic Review

Osteoporosis is a globally relevant public health issue. Our study aimed to summarize the knowledge on the proteomic biomarkers for low bone mineral density over the last years. We conducted a systematic review following the PRISMA guidelines; the scoured databases were PubMed, Web of Sciences, Scopus, and EBSCO, from inception to 2 June 2023. A total of 610 relevant studies were identified and 33 were assessed for eligibility. Finally, 29 studies met the criteria for this systematic review. The risk of bias was evaluated using the Joanna Briggs Institute Critical Appraisal Checklist tool. From the studies selected, 154 proteins were associated with changes of bone mineral density, from which only 10 were reported in at least two articles. The protein-protein network analysis indicated potential biomarkers involved in the skeletal system, immune system process, regulation of protein metabolic process, regulation of signaling, transport, cellular component assembly, cell differentiation, hemostasis, and extracellular matrix organization. Mass spectrometry-based proteomic profiling has allowed the discovery of new biomarkers with diagnostic potential. However, it is necessary to compare and validate the potential biomarkers in different populations to determine their association with bone metabolism and evaluate their translation to the clinical management of osteoporosis.

A review of the world's salt reduction policies and strategies - preparing for the upcoming year 2025

Excessive consumption of dietary sodium is a significant contributor to non-communicable diseases, including hypertension and cardiovascular disease. There is now a global consensus that regulating salt intake is among the most cost-effective measures for enhancing public health. More than half of the countries worldwide have implemented multiple strategies to decrease salt consumption. Nevertheless, a report on sodium intake reduction published by the World Health Organization revealed that the world is off-track to meet its targeted reduction of 30% by 2025. The global situation regarding salt reduction remains concerning. This review will center on domestic and international salt reduction policies, as well as diverse strategies, given the detrimental effects of excessive dietary salt intake and the existing global salt intake scenario. Besides, we used visualization software to analyze the literature related to salt reduction research in the last five years to explore the research hotspots in this field. Our objective is to enhance public awareness regarding the imperative of reducing salt intake and promoting the active implementation of diverse salt reduction policies.

Current Mouse Models of Intracranial Aneurysms: Analysis of Pharmacological Agents Used to Induce Aneurysms and Their Impact on Translational Research

Intracranial aneurysms (IAs) are rare vascular lesions that are more frequently found in women. The pathophysiology behind the formation and growth of IAs is complex. Hence, to date, no single pharmacological option exists to treat them. Animal models, especially mouse models, represent a valuable tool to explore such complex scientific questions. Genetic modification in a mouse model of IAs, including deletion or overexpression of a particular gene, provides an excellent means for examining basic mechanisms behind disease pathophysiology and developing novel pharmacological approaches. All existing animal models need some pharmacological treatments, surgical interventions, or both to develop IAs, which is different from the spontaneous and natural development of aneurysms under the influence of the classical risk factors. The benefit of such animal models is the development of IAs in a limited time. However, clinical translation of the results is often challenging because of the artificial course of IA development and growth. Here, we summarize the continuous improvement in mouse models of IAs. Moreover, we discuss the pros and cons of existing mouse models of IAs and highlight the main translational roadblocks and how to improve them to increase the success of translational IA research.

Disulfidptosis-related Protein RPN1 may be a Novel Anti-osteoporosis Target of Kaempferol

BACKGROUND

Osteoporosis (OP) is an age-related skeletal disease. Kaempferol can regulate bone mesenchymal stem cells (BMSCs) osteogenesis to improve OP, but its mechanism related to disulfidptosis, a newly discovered cell death mechanism, remains unclear.

OBJECTIVE

The study aimed to investigate the biological function and immune mechanism of disulfidptosis- related ribophorin I (RPN1) in OP and to experimentally confirm that RPN1 is the target for the treatment of OP with kaempferol.

METHODS

Differential expression analysis was conducted on disulfide-related genes extracted from the GSE56815 and GSE7158 datasets. Four machine learning algorithms identified disease signature genes, with RPN1 identified as a significant risk factor for OP through the nomogram. Validation of RPN1 differential expression in OP patients was performed using the GSE56116 dataset. The impact of RPN1 on immune alterations and biological processes was explored. Predictive ceRNA regulatory networks associated with RPN1 were generated via miRanda, miRDB, and TargetScan databases. Molecular docking estimated the binding model between kaempferol and RPN1. The targeting mechanism of kaempferol on RPN1 was confirmed through pathological HE staining and immunohistochemistry in ovariectomized (OVX) rats.

RESULTS

RPN1 was abnormally overexpressed in the OP cohort, associated with TNF signaling, hematopoietic cell lineage, and NF-kappa B pathway. Immune infiltration analysis showed a positive correlation between RPN1 expression and CD8+ T cells and resting NK cells, while a negative correlation with CD4+ naive T cells, macrophage M1, T cell gamma delta, T cell follicular helper cells, activated mast cells, NK cells, and dendritic cells, was found. Four miRNAs and 17 lncRNAs associated with RPN1 were identified. Kaempferol exhibited high binding affinity (-7.2 kcal/mol) and good stability towards the RPN1. The experimental results verified that kaempferol could improve bone microstructure destruction and reverse the abnormally high expression of RPN1 in the femur of ovariectomized rats.

CONCLUSION

RPN1 may be a new diagnostic biomarker in patients with OP, and may serve as a new target for kaempferol to improve OP.

Salt Behind the Scenes of Systemic Lupus Erythematosus and Rheumatoid Arthritis

PURPOSE OF REVIEW

Sodium is vital for human health. High salt intake is a global health problem and is associated with cardiovascular morbidity and mortality. Recent evidence suggests that both innate and adaptive immune systems are affected by sodium. In general, excess salt intake drives immune cells toward a pro-inflammatory phenotype. The incidence of autoimmune diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), is steadily increasing. As excess salt induces a pro-inflammatory state, increased salt intake may have impacts on autoimmune diseases. The relationship between salt intake and autoimmune diseases is most widely studied in patients with SLE or RA. This review aimed to summarize the relationship between salt intake and SLE and RA.

RECENT FINDINGS

Most, but not all, of these studies showed that high salt intake might promote SLE by M1 macrophage shift, increase in Th17/Treg cell ratio, activation of dendritic and follicular helper T cells, and increased secretion of pro-inflammatory cytokines. In RA, apart from driving immune cells toward a pro-inflammatory state, high salt intake also influences cellular signaling pathways, including receptor activator of nuclear factor κB ligand (RANKL), Rho GTPases, and MAPK (mitogen-activated protein kinase). There is now sufficient evidence that excess salt intake may be related to the development and progression of SLE and RA, although there are still knowledge gaps. More studies are warranted to further highlight the relationship between excess salt intake, SLE, and RA. Salt intake may affect cell types and pro-inflammatory cytokines and signaling pathways associated with the development and progression of systemic lupus erythematosus and rheumatoid arthritis. Bcl-6 B-cell lymphoma, 6 Erk extracellular signal-regulated kinases, IFN-γ interferon-gamma, JNK c-Jun N-terminal kinase, IL-4 interleukin 4, IL-6 interleukin 6, MAPK mitogen-activated protein kinase, STAT signal transducer and activator of transcription, Tnf-α tumor necrosis factor, Treg T regulatory cell.

Identification of Key Osteoporosis Genes Through Comparative Analysis of Men's and Women's Osteoblast Transcriptomes

Osteoporosis disproportionately affects older women, yet gender differences in human osteoblasts remain unexplored. Identifying mechanisms and biomarkers of osteoporosis will enable the development of preventative and therapeutic approaches. Transcriptome data of 187 osteoblast samples from men and women were compared. Differentially expressed genes (DEGs) were identified, and weighted gene co-expression network analysis (WGCNA) was used to discover co-expressed modules. Enrichment analysis was performed to annotate DEGs. Preservation analysis determined whether modules and pathways were similar between genders. Blood methylation, transcriptome data, mouse phenotype data, and drug treatment data were utilized to identify key osteoporosis genes. We identified 1460 DEGs enriched in immune response, neurogenesis, and GWAS osteoporosis-related genes. WGCNA uncovered 8 modules associated with immune response, development, collagen metabolism, mitochondrion, and amino acid synthesis. Preservation analysis indicated modules and pathways were generally similar between genders. Incorporating GWAS and mouse phenotype data revealed 9 key genes, including GMDS, SMOC2, SASH1, MMP2, AHCYL1, ARRDC2, IGHMBP2, ATP6V1A, and CTSK. These genes were differentially methylated in patient blood and differentiated high and low bone mineral density patients in pre- and postmenopausal women. Denosumab treatment in postmenopausal women down-regulated 6 key genes, up-regulated T cell proportions, and down-regulated fibroblast proportion. qRT-PCR was used to confirm the genes in postmenopausal women. We identified 9 key osteoporosis genes by comparing the transcriptome of osteoblasts in women and men. Our findings' clinical implications were confirmed by multi-omics data and qRT-PCR, and our study provides novel biomarkers and therapeutic targets for osteoporosis diagnosis and treatment.

High Salt Diet Impairs Male Fertility in Mice via Modulating the Skeletal Homeostasis

Male reproductive functions and bone health are both adversely affected by the high salt diet (HSD). Nevertheless, the underlying mechanism via which it alters the sperm function remains largely unknown. This study examines the mechanism by which HSD affects male fertility by impairing bone health. For investigating the same, male BALB/c mice were categorized into three groups-HSD group (fed with 4% NaCl), a low salt diet (LSD) group (fed with 0.4% NaCl), and a control group (fed with a normal diet) for 6 weeks and thereafter assessed for various sperm parameters, bone turnover markers, and testosterone levels. Furthermore, the quantitative assessment of testosterone biosynthesis enzymes was performed. Interestingly, we observed that mice fed with HSD showed significant alterations in sperm parameters-motility, count, and vitality, including morphological changes compared to both the LSD and the control groups. In addition, serum analysis showed an increase in bone resorption markers and a decrease in bone formation markers in the HSD group (p < 0.05). Further, HSD caused a decrease in the testosterone level and mRNA expression of testosterone biosynthesis enzymes. Importantly, a significant decrease in bone formation marker osteocalcin (OC) was observed to coincide with the dip in testosterone level in the HSD group. Given that OC plays a key role in maintaining male fertility, the above findings suggest that a decrease in OC levels may affect the testosterone biosynthesis pathway, reducing testosterone hormone secretion and thereby resulting in decreased spermatogenesis. The study for the first time delineates and bridges the mechanism of HSD-mediated bone loss (results in a deficiency of OC) with decreased testosterone biosynthesis and thus impaired male fertility.

Advancing our understanding of the influence of drug induced changes in the gut microbiome on bone health

The gut microbiome has been implicated in a multitude of human diseases, with emerging evidence linking its microbial diversity to osteoporosis. This review article will explore the molecular mechanisms underlying perturbations in the gut microbiome and their influence on osteoporosis incidence in individuals with chronic diseases. The relationship between gut microbiome diversity and bone density is primarily mediated by microbiome-derived metabolites and signaling molecules. Perturbations in the gut microbiome, induced by chronic diseases can alter bacterial diversity and metabolic profiles, leading to changes in gut permeability and systemic release of metabolites. This cascade of events impacts bone mineralization and consequently bone mineral density through immune cell activation. In addition, we will discuss how orally administered medications, including antimicrobial and non-antimicrobial drugs, can exacerbate or, in some cases, treat osteoporosis. Specifically, we will review the mechanisms by which non-antimicrobial drugs disrupt the gut microbiome's diversity, physiology, and signaling, and how these events influence bone density and osteoporosis incidence. This review aims to provide a comprehensive understanding of the complex interplay between orally administered drugs, the gut microbiome, and osteoporosis, offering new insights into potential therapeutic strategies for preserving bone health.

Admission NLPR predicts long-term mortality in patients with acute ischemic stroke: A retrospective analysis of the MIMIC-III database

BACKGROUND

The neutrophil to lymphocyte*platelet ratio (NLPR) is a new index based on platelets, neutrophils, and lymphocytes associated with the prognosis of patients with infectious diseases and cancer. However, its use in acute ischemic stroke has rarely been reported. This study examined the relationship between levels of systemic immunoinflammatory indices at admission and patient outcomes at different times after onset to assess stroke prognosis by NLPR.

METHODS

This was a retrospective cohort study. The data from 1222 stroke patients were obtained from multi-parameter intelligent monitoring in the Intensive Care III database(MIMIC- III). Cox proportional risk model was conducted to evaluate the relation between NLPR, all-cause mortality, and ischemic. The results were further verified via a subgroup analysis.

RESULTS

After adjusting for multiple covariates, it was found that NLPR was related with all-cause mortality in stroke patients. High NLPR was accompanied by an increase in mortality with longer follow-up (30 days: HR = 1.52, 95% CI = 1.14-2.02,90 days: HR = 1.67, 95% CI = 1.29-2.16, 365 days: HR = 1.56, 95% CI = 1.24-1.96 and 2 years: HR = 1.52, 95% CI = 1.22-1.89).

CONCLUSION

The neutrophil to lymphocyte*platelet ratio (NLPR) are related to long-term adverse outcomes in patients with acute ischemic stroke. Therefore, NLPR is a promising inflammatory index for predicting the long-term prognosis of stroke.

Microcystin-leucine-arginine impairs bone microstructure and biomechanics by activating osteoimmune response and inhibiting osteoblasts maturation in developing rats

Microcystin-LR (MC-LR) affects bone health in adult mice via osteo-immunomodulation. However, its effect on osteoblasts and bone development is unclear. This study investigated the effect of MC-LR on bone osteoimmune and osteoblasts in the developing period. 18 Four-week-old male Sprague Dawley rats were divided into two groups (n = 9 per group) and exposed to 0 (control) and 1 μg/kg b.w. MC-LR (exposure) by intraperitoneal injection for four weeks. The heart blood was collected for serological examination, and the femur for morphological, histopathological, and biomechanical analysis. MC-LR exposure significantly weakened bone microstructures (bone volume, bone volume/total volume, bone trabecular number, connectivity density) and biomechanics (maximum loads and maximum deflection) (P < 0.05). Besides, MC-LR decreased serum procollagen type І car-boxy-terminal propeptide, osteocalcin, bone morphogenetic protein-2, osteoprotegerin, and receptor activator of nuclear factor κB ligand, while elevating osteoclasts number, matrix metalloproteinase-9, β-catenin, Runt-related transcription factor 2, and osterix in bone, and bone alkaline phosphate, C-terminal cross-linked telopeptide of type-I collagen, tartrate-resistant acid phosphatase-5b in serum (P < 0.05). Moreover, MC-LR increased CD4+ T-cells, CD4+/CD8+, M1 and M2 macrophages, and cells apoptosis in the bone marrow, interleukin-6, interleukin-17, and tumor necrosis factor-α in serum, decreased serum interleukin-10 (P < 0.05). Overall, MC-LR can promote bone resorption by activating osteoclasts via osteoimmunology, which may involve macrophages besides lymphocytes. MC-LR may inhibit bone formation by stopping the osteoblasts at an immature stage. Thus, MC-LR weakened bone microstructure and biomechanics in developing period. Its risk on bone development needs further study.

Identification of 12 hub genes associated to the pathogenesis of osteoporosis based on microarray and single-cell RNA sequencing data

Osteoporosis is a common disease, especially among the elderly. This study aimed to comprehensively examine the roles of immune microenvironment in osteoporosis pathogenesis. Expression profiles of GSE35959, GSE7158, and GSE13850 datasets were used to analyze differential expression and identify hub genes related to immune features. Based on the single-cell RNA sequencing (scRNA-seq) data of an osteoporosis patient, different cell types were classified and the relation between immune environment and osteoporosis was explored. Twelve hub genes significantly associated with immune features were selected and 11 subgroups were defined using scRNA-seq data. The expression of two hub genes (CDKN1A and TEFM) was greatly altered during the transformation from mesenchymal stem cells (MSCs) to osteoblasts. Chemokines and chemokine receptors were differentially enriched in different cell types. CXCL12 was high-expressed in MSCs. This study emphasized that immune microenvironment played a critical role in the pathogenesis of osteoporosis. Chemokines and chemokine receptors can modify cell development and affect the interactions among different cell types, leading to unbalanced bone remodeling.

Fine-tuning osteoclastogenesis: An insight into the cellular and molecular regulation of osteoclastogenesis

Osteoclasts, the bone-resorbing cells, are essential for the bone remodeling process and are involved in the pathophysiology of several bone-related diseases. The extensive corpus of in vitro research and crucial mouse model studies in the 1990s demonstrated the key roles of monocyte/macrophage colony-stimulating factor, receptor activator of nuclear factor kappa B ligand (RANKL) and integrin αvβ3 in osteoclast biology. Our knowledge of the molecular mechanisms by which these variables control osteoclast differentiation and function has significantly advanced in the first decade of this century. Recent developments have revealed a number of novel insights into the fundamental mechanisms governing the differentiation and functional activity of osteoclasts; however, these mechanisms have not yet been adequately documented. Thus, in the present review, we discuss various regulatory factors including local and hormonal factors, innate as well as adaptive immune cells, noncoding RNAs (ncRNAs), etc., in the molecular regulation of the intricate and tightly regulated process of osteoclastogenesis. ncRNAs have a critical role as epigenetic controllers of osteoclast physiologic activities, including differentiation and bone resorption. The primary ncRNAs, which include micro-RNAs, circular RNAs, and long noncoding RNAs, form a complex network that affects gene transcription activities associated with osteoclast biological activity. Greater knowledge of the involvement of ncRNAs in osteoclast biological activities will contribute to the treatment and management of several skeletal diseases such as osteoporosis, osteoarthritis, rheumatoid arthritis, etc. Moreover, we further outline potential therapies targeting these regulatory pathways of osteoclastogenesis in distinct bone pathologies.

Impact of T helper cells on bone metabolism in systemic lupus erythematosus

Systemic lupus erythematosus (SLE), an autoimmune disease affecting multiple organs and tissues, is often complicated by musculoskeletal diseases. T helper cells (Th) play an important role in mediating lupus. With the rise of osteoimmunology, more studies have shown shared molecules and interactions between the immune system and bones. Th cells are vital in the regulation of bone metabolism by directly or indirectly regulating bone health by secreting various cytokines. Therefore, by describing the regulation of Th cells (including Th1, Th2, Th9, Th17, Th22, regulatory T cells (Treg), and follicular T helper cells (Tfh) in bone metabolism in SLE, this paper offers certain theoretical support for abnormal bone metabolism in SLE and provides new prospects for future drug development.

The sodium does not affect joint pain and functional activity of knee osteoarthritis patients

Background: The sodium may aggravate synovial inflammation and cartilage thinning. This incidence can cause joint pain and reduce functional activity. Not many people know the effect of sodium on the incidence of OA. Objective: This study aims to determine the relationship between sodium in the body and knee joint pain which results in functional activity. Methods: The quantitative descriptive study used accidental sampling. The study was conducted at three outpatient polyclinic orthopedics of hospitals and was approved by the Health Ethics Committee. All data were collected during the interview. The Semi-Quantitative Food Frequency Questionnaire (SQ-FFQ) and the Nutrisurvey Indonesia 2007 application were used as a tool to collect daily sodium intake (mg). Knee joint pain score was measured using the Visual Analog Scale (VAS) while functional body activity was measured using the Western Ontario McMaster Osteoarthritis Index (WOMAC). The Pearson and Spearman test (p<0.05) were used as a correlation test. Results: 80 subjects were according to the inclusion criteria. Characteristics of the subjects were pre-elderly (32, 40%), women (74, 92.5%), BMI≥ 30 kg/m2 (54, 67.5%) and occupation (43, 53.75%). Average sodium intake = 2090.78 ± 1084.33 mg, VAS score = 6.28 ± 1.95 and WOMAC score = 32.65 ± 14.88. The correlation sodium, VAS, and WOMAC were not significant (p=0.196, p=0.372). Conclusions: Increased sodium intake is not associated with knee joint pain and functional body activity.

Cissus quadrangularis (Hadjod) Inhibits RANKL-Induced Osteoclastogenesis and Augments Bone Health in an Estrogen-Deficient Preclinical Model of Osteoporosis Via Modulating the Host Osteoimmune System

Osteoporosis is a systemic skeletal disease characterised by low bone mineral density (BMD), degeneration of bone micro-architecture, and impaired bone strength. Cissus quadrangularis (CQ), popularly known as Hadjod (bone setter) in Hindi, is a traditional medicinal herb exhibiting osteoprotective potential in various bone diseases, especially osteoporosis and fractures. However, the cellular mechanisms underpinning its direct effect on bone health through altering the host immune system have never been elucidated. In the present study, we interrogated the osteoprotective and immunoporotic (the osteoprotective potential of CQ via modulating the host immune system) potential of CQ in preventing inflammatory bone loss under oestrogen-deficient conditions. The current study outlines the CQ's osteoprotective potential under both ex vivo and in vivo (ovariectomized) conditions. Our ex vivo data demonstrated that, in a dose-dependent manner CQ, suppresses the RANKL-induced osteoclastogenesis (p < 0.001) as well as inhibiting the osteoclast functional activity (p < 0.001) in mouse bone marrow cells (BMCs). Our in vivo µ-CT and flow cytometry data further showed that CQ administration improves bone health and preserves bone micro-architecture by markedly raising the proportion of anti-osteoclastogenic immune cells, such as Th1 (p < 0.05), Th2 (p < 0.05), Tregs (p < 0.05), and Bregs (p < 0.01), while concurrently lowering the osteoclastogenic Th17 cells in bone marrow, mesenteric lymph nodes, Peyer's patches, and spleen in comparison to the control group. Serum cytokine analysis further supported the osteoprotective and immunoporotic potential of CQ, showing a significant increase in the levels of anti-osteoclastogenic cytokines (p < 0.05) (IFN-γ, IL-4, and IL-10) and a concurrent decrease in the levels of osteoclastogenic cytokines (p < 0.05) (TNF-α, IL-6, and IL-17). In conclusion, our data for the first time delineates the novel cellular and immunological mechanism of the osteoprotective potential of CQ under postmenopausal osteoporotic conditions.

Remodeling of the osteoimmune microenvironment after biomaterials implantation in murine tibia: Single-cell transcriptome analysis

Osseointegration seems to be a foreign body reaction equilibrium due to the complicated interactions between the immune and skeletal systems. The heterogeneity of the osteoimmune microenvironment in the osseointegration of implant materials remains elusive. Here, a single-cell study involving 40043 cells is conducted, and a total of 10 distinct cell clusters are identified from five different groups. A preliminary description of the osteoimmune microenvironment revealed the diverse cellular heterogeneity and dynamic changes modulated by implant properties. The increased immature neutrophils, Ly6C ⁺ CCR2^hi monocytes, and S100a8^hi macrophages induce an aggressive inflammatory response and eventually lead to the formation of fibrous capsule around the stainless steel implant. The enrichment of mature neutrophils, FcgR1^hi and differentiated immunomodulatory macrophages around the titanium implant indicates favorable osseointegration under moderate immune response. Neutrophil-depletion mice are conducted to explore the role of neutrophils in osseointegration. Neutrophils may improve bone formation by enhancing the recruitment of BMSCs via the CXCL12/CXCR3 signal axis. These findings contribute to a better knowledge of osteoimmunology and are valuable for the design and modification of 'osteoimmune-smart' biomaterials in the bone regeneration field.

Immunology of osteoporosis: relevance of inflammatory targets for the development of novel interventions

Osteoporosis is recognized as low bone mass and deteriorated bone microarchitecture. It is the leading cause of fractures and consequent morbidity globally. The established pathophysiological evidence favors the endocrine factors for osteoporosis and the role of the immune system on the skeletal system has been recently identified. Due to the common developmental niche bone and immune system interactions have led to the emergence of osteoimmunology. Immune dysregulation can initiate inflammatory conditions that adversely affect bone integrity. The role of immune cells, such as T-lymphocytes subsets (Th17), cannot be neglected in the pathogenesis of osteoporosis. Local inflammation within the bone from any cause attracts immune cells that participate in the activation of osteoclasts. This work summarizes the present knowledge of osteoimmunology in reference to osteoporosis and identifies novel targets for immunotherapy of osteoporosis.

The modulatory effect of high salt on immune cells and related diseases

BACKGROUND

The adverse effect of excessive salt intake has been recognized in decades. Researchers have mainly focused on the association between salt intake and hypertension. However, studies in recent years have proposed the existence of extra-renal sodium storage and provided insight into the immunomodulatory function of sodium.

OBJECTIVES

In this review, we discuss the modulatory effects of high salt on various innate and adaptive immune cells and immune-regulated diseases.

METHODS

We identified papers through electronic searches of PubMed database from inception to March 2022.

RESULTS

An increasing body of evidence has demonstrated that high salt can modulate the differentiation, activation and function of multiple immune cells. Furthermore, a high-salt diet can increase tissue sodium concentrations and influence the immune responses in microenvironments, thereby affecting the development of immune-regulated diseases, including hypertension, multiple sclerosis, cancer and infections. These findings provide a novel mechanism for the pathology of certain diseases and indicate that salt might serve as a target or potential therapeutic agent in different disease contexts.

CONCLUSION

High salt has a profound impact on the differentiation, activation and function of multiple immune cells. Additionally, an HSD can modulate the development of various immune-regulated diseases.

Your Regulatory T Cells Are What You Eat: How Diet and Gut Microbiota Affect Regulatory T Cell Development

Modern industrial practices have transformed the human diet over the last century, increasing the consumption of processed foods. Dietary imbalance of macro- and micro-nutrients and excessive caloric intake represent significant risk factors for various inflammatory disorders. Increased ingestion of food additives, residual contaminants from agricultural practices, food processing, and packaging can also contribute deleteriously to disease development. One common hallmark of inflammatory disorders, such as autoimmunity and allergies, is the defect in anti-inflammatory regulatory T cell (Treg) development and/or function. Treg represent a highly heterogeneous population of immunosuppressive immune cells contributing to peripheral tolerance. Tregs either develop in the thymus from autoreactive thymocytes, or in the periphery, from naïve CD4⁺ T cells, in response to environmental antigens and cues. Accumulating evidence demonstrates that various dietary factors can directly regulate Treg development. These dietary factors can also indirectly modulate Treg differentiation by altering the gut microbiota composition and thus the production of bacterial metabolites. This review provides an overview of Treg ontogeny, both thymic and peripherally differentiated, and highlights how diet and gut microbiota can regulate Treg development and function.

Substance P, A Promising Therapeutic Target in Musculoskeletal Disorders

A large number of studies have focused on the role of substance P (SP) and the neurokinin-1 receptor (NK1R) in the pathogenesis of a variety of medical conditions. This review provides an overview of the role of the SP-NK1R pathway in the pathogenesis of musculoskeletal disorders and the evidence for its role as a therapeutic target for these disorders, which are major public health problems in most countries. To summarize, the brief involvement of SP may affect tendon healing in an acute injury setting. SP combined with an adequate conjugate can be a regenerative therapeutic option in osteoarthritis. The NK1R antagonist is a promising agent for tendinopathy, rheumatoid arthritis, and osteoarthritis. Research on the SP-NK1R pathway will be helpful for developing novel drugs for osteoporosis.

High dietary salt intake activates inflammatory cascades via Th17 immune cells: impact on health and diseases

The incidence of immune-mediated inflammatory diseases (IMIDs) is on the rise. A high salt content in the diet was found to play a crucial role in mediating IMIDs. It was demonstrated that increased salt concentration favors the differentiation of CD4+ cells to pathogenic Th17 cells, which predispose to several inflammatory diseases by modulating the immunological milieu. In auto-immune diseases increased salt concentration causes stable induction of Th17 cells. In cancer, increased salt concentration triggers chronic inflammation and increases vascular endothelial growth factor levels. Salt-mediated proliferation of Th17 cells has been found to reduce nitric oxide production in the endothelial cells, leading to hypertension. Increased salt concentration was found to alter the intestinal flora, which favors local inflammation. This review attempts to explain the role of high salt concentration and its molecular pathways in causing IMIDs.

Integrated Bioinformatic Analysis of the Shared Molecular Mechanisms Between Osteoporosis and Atherosclerosis

BACKGROUND

Osteoporosis and atherosclerosis are common in the elderly population, conferring a heavy worldwide burden. Evidence links osteoporosis and atherosclerosis but the exact underlying common mechanism of its occurrence is unclear. The purpose of this study is to further explore the molecular mechanism between osteoporosis and atherosclerosis through integrated bioinformatic analysis.

METHODS

The microarray data of osteoporosis and atherosclerosis in the Gene Expression Omnibus (GEO) database were downloaded. The Weighted Gene Co-Expression Network Analysis (WGCNA) and differentially expressed genes (DEGs) analysis were used to identify the co-expression genes related to osteoporosis and atherosclerosis. In addition, the common gene targets of osteoporosis and atherosclerosis were analyzed and screened through three public databases (CTD, DISEASES, and GeneCards). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed by Metascape. Then, the common microRNAs (miRNAs) in osteoporosis and atherosclerosis were screened out from the Human microRNA Disease Database (HMDD) and the target genes of whom were predicted through the miRTarbase. Finally, the common miRNAs-genes network was constructed by Cytoscape software.

RESULTS

The results of common genes analysis showed that immune and inflammatory response may be a common feature in the pathophysiology of osteoporosis and atherosclerosis. Six hub genes (namely, COL1A1, IBSP, CTSD, RAC2, MAF, and THBS1) were obtained via taking interaction of different analysis results. The miRNAs-genes network showed that has-let-7g might play an important role in the common mechanisms between osteoporosis and atherosclerosis.

CONCLUSION

This study provides new sights into shared molecular mechanisms between osteoporosis and atherosclerosis. These common pathways and hub genes may offer promising clues for further experimental studies.

Distribution and reference interval establishment of neutral-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), and platelet-to-lymphocyte ratio (PLR) in Chinese healthy adults

Background

Neutral‐to‐lymphocyte ratio (NLR), lymphocyte‐to‐monocyte ratio (LMR), and platelet‐to‐lymphocyte ratio (PLR) are associated with coronavirus disease 2019 (COVID‐19) and many diseases, but there are few data about the reference interval (RI) of NLR, LMR, and PLR.

Methods

The neutrophil count, lymphocyte count, monocyte count, and platelet count of 404,272 Chinese healthy adults (>18 years old) were measured by Sysmex XE‐2100 automatic hematology analyzer, and NLR, LMR, and PLR were calculated. According to CLSI C28‐A3, the nonparametric 95% percentile interval is defined as the reference interval.

Results

The results of Mann‐Whitney U test showed that NLR (p < .001) in male was significantly higher than that in female; LMR (p < .001) and PLR (p < .001) in male were significantly lower than that in female. Kruskal‐Wallis H test showed that there were significant differences in NLR, LMR, and PLR among different genders and age groups (p < .001). The linear graph showed that the reference upper limit of NLR and PLR increased with age and the reference upper limit of LMR decreases with age in male population. In female population, the reference upper limit of NLR in 50–59 group, LMR in >80 group, and PLR in 70–79 group appeared a trough; the reference upper limit of NLR in >80 group, LMR in 50–59 group, and PLR in 40–49 group appeared peak.

Conclusion

The establishment of RI for NLR, LMR, and PLR in Chinese healthy adults according to gender and age will promote the standardization of clinical application.

Gut microbiota and bone metabolism

Osteoporosis is the most common metabolic skeletal disease. It is characterized by the deterioration of the skeletal microarchitecture and bone loss, leading to ostealgia, and even bone fractures. Accumulating evidence has indicated that there is an inextricable relationship between the gut microbiota (GM) and bone homeostasis involving host-microbiota crosstalk. Any perturbation of the GM can play an initiating and reinforcing role in disrupting the bone remodeling balance during the development of osteoporosis. Although the GM is known to influence bone metabolism, the mechanisms associated with these effects remain unclear. Herein, we review the current knowledge of how the GM affects bone metabolism in health and disease, summarize the correlation between pathogen-associated molecular patterns of GM structural components and bone metabolism, and discuss the potential mechanisms underlying how GM metabolites regulate bone turnover. Deciphering the complicated relationship between the GM and bone health will provide new insights into the prevention and treatment of osteoporosis.

Single-cell RNA sequencing of human femoral head in vivo

The homeostasis of bone metabolism depends on the coupling and precise regulation of various types of cells in bone tissue. However, the communication and interaction between bone tissue cells at the single-cell level remains poorly understood. Thus, we performed single-cell RNA sequencing (scRNA-seq) on the primary human femoral head tissue cells (FHTCs). Nine cell types were identified in 26,574 primary human FHTCs, including granulocytes, T cells, monocytes, B cells, red blood cells, osteoblastic lineage cells, endothelial cells, endothelial progenitor cells (EPCs) and plasmacytoid dendritic cells. We identified serine protease 23 (PRSS23) and matrix remodeling associated protein 8 (MXRA8) as novel bone metabolism-related genes. Additionally, we found that several subtypes of monocytes, T cells and B cells were related to bone metabolism. Cell-cell communication analysis showed that collagen, chemokine, transforming growth factor and their ligands have significant roles in the crosstalks between FHTCs. In particular, EPCs communicated with osteoblastic lineage cells closely via the "COL2A1-ITGB1" interaction pair. Collectively, this study provided an initial characterization of the cellular composition of the human FHTCs and the complex crosstalks between them at the single-cell level. It is a unique starting resource for in-depth insights into bone metabolism.

Cancer Salt Nostalgia

High-salt (sodium chloride) diets have been strongly associated with disease states and poor health outcomes. Traditionally, the impact of salt intake is primarily studied in cardiovascular diseases, hypertension and renal diseases; however, recently there has been increasing evidence demonstrating the role of salt in autoimmune diseases. Salt has been shown to modulate the inflammatory activation of immune cells leading to chronic inflammation-related ailments. To date, there is minimal evidence showing a direct correlation of salt with cancer incidence and/or cancer-related adverse clinical outcomes. In this review article, we will discuss the recent understanding of the molecular role of salt, and elucidate the apparent double-edged sword nature of the relationship between salt and cancer progression.

Ex Vivo High Salt Activated Tumor-Primed CD4+T Lymphocytes Exert a Potent Anti-Cancer Response

Simple Summary

Cell based immunotherapy is rapidly emerging as a promising cancer treatment. Salt (sodium chloride) treatment to immune cell cultures is known to induce inflammatory activation. In our current study, we analyzed the anti-cancer ability of salt treatment on immune cells outside the host followed by reinfusion into the host. Using a pre-clinical breast cancer model, we demonstrated that external salt treatment on T-cell subset of immune cells produced a viable anti-cancer response, which may have future human clinical application.

Abstract

Cell based immunotherapy is rapidly emerging as a promising cancer treatment. A modest increase in salt (sodium chloride) concentration in immune cell cultures is known to induce inflammatory phenotypic differentiation. In our current study, we analyzed the ability of salt treatment to induce ex vivo expansion of tumor-primed CD4 (cluster of differentiation 4)+T cells to an effector phenotype. CD4+T cells were isolated using immunomagnetic beads from draining lymph nodes and spleens from tumor bearing C57Bl/6 mice, 28 days post-injection of Py230 syngeneic breast cancer cells. CD4+T cells from non-tumor bearing mice were isolated from splenocytes of 12-week-old C57Bl/6 mice. These CD4+T cells were expanded ex vivo with five stimulation cycles, and each cycle comprised of treatment with high salt (Δ0.035 M NaCl) or equimolar mannitol controls along with anti-CD3/CD28 monoclonal antibodies for the first 3 days, followed by the addition of interleukin (IL)-2/IL-7 cytokines and heat killed Py230 for 4 days. Ex vivo high salt treatment induced a two-fold higher Th1 (T helper type 1) expansion and four-fold higher Th17 expansion compared to equimolar mannitol treatment. Importantly, the high salt expanded CD4+T cells retained tumor-specificity, as demonstrated by higher in vitro cytotoxicity against Py230 breast cancer cells and reduced in vivo syngeneic tumor growth. Metabolic studies revealed that high salt treatment enhanced the glycolytic reserve and basal mitochondrial oxidation of CD4+T cells, suggesting a role of high salt in enhanced pro-growth anabolic metabolism needed for inflammatory differentiation. Mechanistic studies demonstrated that the high salt induced switch to the effector phenotype was mediated by tonicity-dependent transcription factor, TonEBP/NFAT5. Using a transgenic murine model, we demonstrated that CD4 specific TonEBP/NFAT5 knock out (CD4^cre/creNFAT5^flox/flox) abrogated the induction of the effector phenotype and anti-tumor efficiency of CD4+T cells following high salt treatment. Taken together, our data suggest that high salt-mediated ex vivo expansion of tumor-primed CD4+T cells could induce effective tumor specific anti-cancer responses, which may have a novel cell-based cancer immunotherapeutic application.

T helper 17 cells in the pathophysiology of acute and chronic kidney disease

Both acute and chronic kidney disease have a strong underlying inflammatory component. This review focuses primarily on T helper 17 (Th17) cells as mediators of inflammation and their potential to modulate acute and chronic kidney disease. We provide updated information on factors and signaling pathways that promote Th17 cell differentiation with specific reference to kidney disease. We highlight numerous clinical studies that have investigated Th17 cells in the setting of human kidney disease and provide updated summaries from various experimental animal models of kidney disease indicating an important role for Th17 cells in renal fibrosis and hypertension. We focus on the pleiotropic effects of Th17 cells in different renal cell types as potentially relevant to the pathogenesis of kidney disease. Finally, we highlight studies that present contrasting roles for Th17 cells in kidney disease progression.

Contribution of Th17 cells to tissue injury in hypertension

PURPOSE OF REVIEW

Hypertension has been demonstrated to be a chief contributor to morbidity and mortality throughout the world. Although the cause of hypertension is multifactorial, emerging evidence, obtained in experimental studies, as well as observational studies in humans, points to the role of inflammation and immunity. Many aspects of immune function have now been implicated in hypertension and end-organ injury; this review will focus upon the recently-described role of Th17 cells in this pathophysiological response.

RECENT FINDINGS

Studies in animal models and human genetic studies point to a role in the adaptive immune system as playing a contributory role in hypertension and renal tissue damage. Th17 cells, which produce the cytokine IL17, are strongly pro-inflammatory cells, which may contribute to tissue damage if expressed in chronic disease conditions. The activity of these cells may be enhanced by physiological factors associated with hypertension such as dietary salt or Ang II. This activity may culminate in the increased sodium retaining activity and exacerbation of inflammation and renal fibrosis via multiple cellular mechanisms.

SUMMARY

Th17 cells are a distinct component of the adaptive immune system that may strongly enhance pathways leading to increased sodium reabsorption, elevated vascular tone and end-organ damage. Moreover, this pathway may lend itself towards specific targeting for treatment of kidney disease and hypertension.

Excessive salt consumption causes systemic calcium mishandling and worsens microarchitecture and strength of long bones in rats

Excessive salt intake has been associated with the development of non-communicable diseases, including hypertension with several cardiovascular consequences. Although the detrimental effects of high salt on the skeleton have been reported, longitudinal assessment of calcium balance together with changes in bone microarchitecture and strength under salt loading has not been fully demonstrated. To address these unanswered issues, male Sprague-Dawley rats were fed normal salt diet (NSD; 0.8% NaCl) or high salt diet (HSD; 8% NaCl) for 5 months. Elevation of blood pressure, cardiac hypertrophy and glomerular deterioration were observed in HSD, thus validating the model. The balance studies were performed to monitor calcium input and output upon HSD challenge. The HSD-induced increase in calcium losses in urine and feces together with reduced fractional calcium absorption led to a decrease in calcium retention. With these calcium imbalances, we therefore examined microstructural changes of long bones of the hind limbs. Using the synchrotron radiation x-ray tomographic microscopy, we showed that trabecular structure of tibia and femur of HSD displayed a marked increase in porosity. Consistently, the volumetric micro-computed tomography also demonstrated a significant decrease in trabecular bone mineral density with expansion of endosteal perimeter in the tibia. Interestingly, bone histomorphometric analyses indicated that salt loading caused an increase in osteoclast number together with decreases in osteoblast number and osteoid volume. This uncoupling process of bone remodeling in HSD might underlie an accelerated bone loss and bone structural changes. In conclusion, long-term excessive salt consumption leads to impairment of skeletal mass and integrity possibly through negative calcium balance.

Lactobacillus rhamnosus attenuates bone loss and maintains bone health by skewing Treg-Th17 cell balance in Ovx mice

Osteoporosis is a systemic-skeletal disorder characterized by enhanced fragility of bones leading to increased rates of fractures and morbidity in large number of populations. Probiotics are known to be involved in management of various-inflammatory diseases including osteoporosis. But no study till date had delineated the immunomodulatory potential of Lactobacillus rhamnosus (LR) in bone-health. In the present study, we examined the effect of probiotic-LR on bone-health in ovariectomy (Ovx) induced postmenopausal mice model. In the present study, we for the first time report that LR inhibits osteoclastogenesis and modulates differentiation of Treg-Th17 cells under in vitro conditions. We further observed that LR attenuates bone loss under in vivo conditions in Ovx mice. Both the cortical and trabecular bone-content of Ovx+LR treated group was significantly higher than Ovx-group. Remarkably, the percentage of osteoclastogenic CD4+Rorγt+Th17 cells at distinct immunological sites such as BM, spleen, LN and PP were significantly reduced, whereas the percentage of anti-osteoclastogenic CD4+Foxp3+Tregs and CD8+Foxp3+Tregs were significantly enhanced in LR-treated group thereby resulting in inhibition of bone loss. The osteoprotective role of LR was further supported by serum cytokine data with a significant reduction in osteoclastogenic cytokines (IL-6, IL-17 and TNF-α) along with enhancement in anti-osteoclastogenic cytokines (IL-4, IL-10, IFN-γ) in LR treated-group. Altogether, the present study for the first time establishes the osteoprotective role of LR on bone health, thus highlighting the immunomodulatory potential of LR in the treatment and management of various bone related diseases including osteoporosis.

Potential mechanisms linking psychological stress to bone health

Chronic psychological stress affects many body systems, including the skeleton, through various mechanisms. This review aims to provide an overview of the factors mediating the relationship between psychological stress and bone health. These factors can be divided into physiological and behavioural changes induced by psychological stress. The physiological factors involve endocrinological changes, such as increased glucocorticoids, prolactin, leptin and parathyroid hormone levels and reduced gonadal hormones. Low-grade inflammation and hyperactivation of the sympathetic nervous system during psychological stress are also physiological changes detrimental to bone health. The behavioural changes during mental stress, such as altered dietary pattern, cigarette smoking, alcoholism and physical inactivity, also threaten the skeletal system. Psychological stress may be partly responsible for epigenetic regulation of skeletal development. It may also mediate the relationship between socioeconomic status and bone health. However, more direct evidence is required to prove these hypotheses. In conclusion, chronic psychological stress should be recognised as a risk factor of osteoporosis and stress-coping methods should be incorporated as part of the comprehensive osteoporosis-preventing strategy.

The Role of Chronic Inflammatory Bone and Joint Disorders in the Pathogenesis and Progression of Alzheimer's Disease

Late-onset Alzheimer's Disease (LOAD) is a devastating neurodegenerative disorder that causes significant cognitive debilitation in tens of millions of patients worldwide. Throughout disease progression, abnormal secretase activity results in the aberrant cleavage and subsequent aggregation of neurotoxic Aβ plaques in the cerebral extracellular space and hyperphosphorylation and destabilization of structural tau proteins surrounding neuronal microtubules. Both pathologies ultimately incite the propagation of a disease-associated subset of microglia-the principle immune cells of the brain-characterized by preferentially pro-inflammatory cytokine secretion and inhibited AD substrate uptake capacity, which further contribute to neuronal degeneration. For decades, chronic neuroinflammation has been identified as one of the cardinal pathophysiological driving features of AD; however, despite a number of works postulating the underlying mechanisms of inflammation-mediated neurodegeneration, its pathogenesis and relation to the inception of cognitive impairment remain obscure. Moreover, the limited clinical success of treatments targeting specific pathological features in the central nervous system (CNS) illustrates the need to investigate alternative, more holistic approaches for ameliorating AD outcomes. Accumulating evidence suggests significant interplay between peripheral immune activity and blood-brain barrier permeability, microglial activation and proliferation, and AD-related cognitive decline. In this work, we review a narrow but significant subset of chronic peripheral inflammatory conditions, describe how these pathologies are associated with the preponderance of neuroinflammation, and posit that we may exploit peripheral immune processes to design interventional, preventative therapies for LOAD. We then provide a comprehensive overview of notable treatment paradigms that have demonstrated considerable merit toward treating these disorders.

Substance P blocks ovariectomy-induced bone loss by modulating inflammation and potentiating stem cell function

Osteoporosis is an age-related disease caused by imbalanced bone remodeling resulting from excessive bone resorption. Osteoporosis is tightly linked with induction of chronic inflammation, which activates osteoclasts and impairs osteoprogenitor in bone marrow. T helper 17 (Th17) cells have been recently recognized as one of major inducers in the pathophysiology of bone loss by secreting IL-17. Thus, modulation of Th17 development is anticipated to affect the progression of osteoporosis.

Substance P (SP) is reported to provide anti-inflammatory effects by controlling immune cell profile and also, promote restoration of damaged stem cell niches—the bone marrow—by repopulating BMSCs or potentiating its paracrine ability. This study aimed to explore the therapeutic effects of systemically injected SP on ovariectomy (OVX)-induced osteoporosis.

Resultantly, SP injection obviously blocked OVX-induced impairment of bone microarchitecture and reduction of the mineral density. In osteoporotic condition, SP could ameliorate chronic inflammation by promoting Treg cell polarization and inhibiting the development of osteoclastogenic Th17 cells. Moreover, SP could rejuvenate stem cell and enable stem cells to repopulate and differentiate into osteoblast.

Collectively, our study strongly suggests that SP treatment can block osteoporosis and furthermore, SP treatment provides therapeutic effect on chronic disease with inflammation and stem cell dysfunction.

The correlation between the Th17/Treg cell balance and bone health

With the ageing of the world population, osteoporosis has become a problem affecting quality of life. According to the traditional view, the causes of osteoporosis mainly include endocrine disorders, metabolic disorders and mechanical factors. However, in recent years, the immune system and immune factors have been shown to play important roles in the occurrence and development of osteoporosis. Among these components, regulatory T (Treg) cells and T helper 17 (Th17) cells are crucial for maintaining bone homeostasis, especially osteoclast differentiation. Treg cells and Th17 cells originate from the same precursor cells, and their differentiation requires involvement of the TGF-β regulated signalling pathway. Treg cells and Th17 cells have opposite functions. Treg cells inhibit the differentiation of osteoclasts in vivo and in vitro, while Th17 cells promote the differentiation of osteoclasts. Therefore, understanding the balance between Treg cells and Th17 cells is anticipated to provide a new idea for the development of novel treatments for osteoporosis.

Spironolactone reduces biochemical markers of bone turnover in postmenopausal women with primary aldosteronism

CONTEXT

Primary aldosteronism (PA) is the most frequent form of endocrine hypertension. Besides its deleterious impact on cardiovascular target organ damage, PA is considered to cause osteoporosis.

PATIENTS AND METHODS

We assessed bone turnover in a subset of 36 postmenopausal women with PA. 18 patients had unilateral PA and were treated by adrenalectomy, whereas 18 patients had bilateral PA and received mineralocorticoid receptor antagonist (MRA) therapy respectively. 18 age- and BMI-matched females served as controls. To estimate bone remodeling, we measured the bone turnover markers intact procollagen 1 N-terminal propeptide, bone alkaline phosphatase, osteocalcin and tartrate resistant acid phosphatase 5b in plasma by chemiluminescent immunoassays at time of diagnosis and one year after initiation of treatment.

STUDY DESIGN

Observational longitudinal cohort study.

SETTING

Tertiary care hospital.

RESULTS

Compared with controls, patients with PA had mildly elevated osteocalcin at baseline (p = 0.013), while the other bone markers were comparable between both groups. There were no differences between the unilateral and the bilateral PA subgroup. One year after initiation of MRA treatment with spironolactone bone resorption and bone formation markers had significantly decreased in patients with bilateral PA. In contrast, patients adrenalectomized because of unilateral PA showed no significant change of bone turnover markers.

CONCLUSION

This study shows that aldosterone excess in postmenopausal women with PA is not associated with a relevant increase of bone turnover markers at baseline. However, we observed a significant decrease of bone markers in patients treated with spironolactone, but not in patients treated by adrenalectomy.

Osteoimmunology: The Regulatory Roles of T Lymphocytes in Osteoporosis

Immune imbalance caused bone loss. Osteoimmunology is emerging as a new interdisciplinary field to explore the shared molecules and interactions between the skeletal and immune systems. In particular, T lymphocytes (T cells) play pivotal roles in the regulation of bone health. However, the roles and mechanisms of T cells in the treatment of osteoporosis are not fully understood. The present review aims to summarize the essential regulatory roles of T cells in the pathophysiology of various cases of osteoporosis and the development of T cell therapy for osteoporosis from osteoimmunology perspective. As T cell-mediated immunomodulation inhibition reduced bone loss, there is an increasing interest in T cell therapy in an attempt to treat osteoporosis. In summary, the T cell therapy may be further pursued as an immunomodulatory strategy for the treatment of osteoporosis, which can provide a novel perspective for drug development in the future.

A Comprehensive Analysis of MicroRNAs in Human Osteoporosis

MicroRNAs (miRNAs) are single-stranded RNA molecules that control gene expression in various processes, such as cancers, Alzheimer's disease, and bone metabolic diseases. However, the regulatory roles of miRNAs in osteoporosis have not been systematically analyzed. Here, we performed a comprehensive analysis to identify the differentially expressed miRNAs involved in osteoporosis. MiRNAs associated with osteoporosis were collected through literature retrieval and further screened based on specific inclusion and exclusion criteria. The osteoporosis therapeutic targets of miRNAs were obtained by the integration of miRWalk 3.0 database and five human disease therapeutic target databases. Then, the network analysis and functional enrichment analysis of miRNAs and their targets were performed. As a result, 11 eligible miRNAs were identified highly associated with osteoporosis. MiRNA-mRNA network demonstrated there were the complex mutual interactions between miRNAs and their targets. Besides, ADRB2, AR, ESR1, FGFR1, TRAF6, etc., were identified as the top hub genes in protein-protein interaction (PPI) network. Functional enrichment analysis revealed that miRNAs and their targets were mainly mapped on processes associated with bone and immune system, such as bone remolding, bone mineralization, PI3K/AKt, TNF signaling pathways and Th17 cell differentiation. RT-PCR results showed that the expression of miR-335-3p was significantly down-regulated in hind limb unloading (HLU) mice tibia samples compared with controls, the remaining 10 miRNAs were significantly up-regulated after HLU (P < 0.01). In summary, we identified 11 differentially expressed miRNAs and their hub target genes in osteoporosis, which may be novel diagnostic biomarkers for osteoporosis.

A high-salt diet aggravates retinal ischaemia/reperfusion injury

Ischaemia/reperfusion contributes to the pathophysiological process of many retinal diseases. Previous studies have shown that retinal ischaemia/reperfusion mainly results in neuronal degeneration, including thinning of the retina, retinal ganglion cell death and reductions in electroretinography. A high-salt diet contributes to the inflammatory response and tissue hypoperfusion and may be associated with ischaemia/reperfusion injury. In the present study, we investigated the influence of a high-salt diet on retinal ischaemia/reperfusion injury and explored the potential mechanism in a rat model. The results revealed that the high-salt diet aggravated ischaemia/reperfusion-induced thinning of the retina. A TUNEL assay and Brn-3a staining revealed substantially more severe cell death and loss of retinal ganglion cells, and electroretinography confirmed worse retinal function in the ischaemia/reperfusion eyes of rats fed the high-salt diet. These effects may be associated with upregulation of Caspase-3, Bax, Interleukin-1β and Interleukin-6 and decreased expression of nitric oxide. In summary, a high-salt diet aggravates ischaemia/reperfusion-induced retinal neuronal impairment by activating pro-apoptotic and pro-inflammatory signalling pathways and inhibiting vasodilation.

Sodium-chloride-induced effects on the expression profile of human periodontal ligament fibroblasts with focus on simulated orthodontic tooth movement

Increased salt (NaCl) consumption triggers chronic diseases such as hypertension or osteopenia. Its impact on orthodontic tooth movement and periodontitis, however, has not been investigated, although both processes are related to the immune system, with periodontal ligament fibroblasts (PDLFs) playing a key mediating role. Here, we investigated the impact of NaCl on the expression pattern of PDLFs in a model of simulated compressive orthodontic strain. Periodontal ligament fibroblasts were preincubated for 24 h with additional 0 or 40 mM NaCl and concurrently treated for another 48 h with or without compressive strain of 2 g cm^-2 . We analyzed the expression of genes and proteins involved in orthodontic tooth movement by reverse transcription quantitative polymerase chain reaction (RT-qPCR), ELISA, and immunoblot. Co-culture experiments were performed to observe PDLF-mediated osteoclastogenesis. A higher (40 mM) concentration of NaCl in the culture medium resulted in increased secretion of prostaglandin, expression of alkaline phosphatase, and expression of genes involved in extracellular matrix remodeling, but decreased compression-induced expression of the interleukin-6 (IL6) gene. The 40 mM concentration of NaCl also enhanced receptor activator of nuclear factor kappa-B ligand (RANKL) but reduced that of osteoprotegerin (OPG), resulting in upregulated PDLF-mediated osteoclastogenesis. A high NaCl concentration in the periodontal ligament, corresponding to a high-salt diet in vivo, may influence orthodontic tooth movement and periodontitis through increased secretion of prostaglandins by PDLFs and upregulated PDLF-mediated osteoclastogenesis, possibly accelerating orthodontic tooth movement and propagating periodontitis and periodontal bone loss.

Role of NFAT5 in the Immune System and Pathogenesis of Autoimmune Diseases

The nuclear factor of activated T cells (NFAT5), also known as a tonicity-responsive enhancer-binding protein, was originally identified as a key transcription factor involved in maintaining cellular homeostasis against hypertonic and hyperosmotic environments. Although NFAT5 has been expressed and studied in various types of hyperosmolar tissues, evidence has emerged that NFAT5 plays a role in the development and activation of immune cells, especially T cells and macrophages. The immune-regulatory function of NFAT5 is achieved by inducing different target genes and different signaling pathways in both tonicity-dependent and -independent manners. Particularly in response to hyperosmotic stress, NFAT5 induces the generation of pathogenic T_H17 cells and pro-inflammatory macrophages, contributing to autoimmune and inflammatory diseases. Meanwhile, with tonicity-independent stimuli, including activation of the Toll-like receptors and inflammatory cytokines, NFAT5 also can be activated and promotes immune cell survival, proliferation, migration, and angiogenesis. Moreover, under isotonic conditions, NFAT5 has been implicated in the pathogenesis of a variety of inflammatory and autoimmune diseases including rheumatoid arthritis. This review describes the current knowledge of NFAT5, focusing on its immune-regulatory functions, and it highlights the importance of NFAT5 as a novel therapeutic target for chronic inflammatory diseases.

Spicy food and self-reported fractures

BACKGROUND & AIMS

Population-based evidence that suggests health effects of spicy consumptions on fracture was scant. The study aimed to explore the association of spicy food intake with self-reported history of fractures in the Chinese populations.

METHODS

Data was drawn from the baseline survey of a large cohort study conducted in China between 2004 and 2008. A total of 512,891 adults (including 302,632 females) were included. Frequency, strength and duration of spicy food consumption were assessed using a survey questionnaire. Fracture history was self-reported based on physician's diagnoses. Multivariate logistic regression models stratified by socio-economic factors, body mass index and other lifestyle factors were performed adjusting for potential confounders.

RESULTS

The prevalence of daily spicy food intake was 30.32% in males and 29.90% in females. The adjusted odds ratios for fractures were 1.04 (95% CI: 1.01-1.07) for those who ate spicy food occasionally, 1.10 (95% CI: 1.05-1.16) for those who ate one or two days a week, 1.15 (95% CI: 1.09-1.20) for three to five days a week, and 1.12 (95% CI: 1.07-1.17) for daily consumers, compared to participants who never ate spicy food. Participants who ate weak spicy food (OR: 1.10, 95% CI: 1.14-1.23), moderate spicy food (OR: 1.11, 95% CI: 1.06-1.15) and strong spicy food (OR: 1.18, 95% CI: 1.12-1.25) were more strongly associated with self-reported history of fracture. In addition, the strengths of associations were consistently stronger with the duration of spicy food exposure. In stratified analyses, the strength of such an association appeared stronger in rural areas (OR: 1.14, 95% CI: 1.09-1.20) than urban (OR: 1.09, 95% CI: 1.05-1.12). The correlation was consistently stronger in males than in females.

CONCLUSIONS

Among Chinese adults, a positive cross-sectional association between the level of spicy food intake and history of fractures was found in both sexes.

Microcystin-leucine arginine (MC-LR) induces bone loss and impairs bone micro-architecture by modulating host immunity in mice: Implications for bone health

Osteoporosis or enhanced bone loss is one of the most commonly occurring bone conditions in the world, responsible for higher incidence of fractures leading to increased morbidity and mortality in adults. Bone loss is affected by various environmental factors including diet, age, drugs, toxins etc. Microcystins are toxins produced by cyanobacteria with microcystin-LR being the most abundantly found around the world effecting both human and animal health. The present study demonstrates that MC-LR treatment induces bone loss and impairs both trabecular and cortical bone microarchitecture along with decreasing the mineral density and heterogeneity of bones in mice. This effect of MC-LR was found due to its immunomodulatory effects on the host immune system, wherein MC-LR skews both T cell (CD4⁺ and CD8⁺ T cells) and B cell populations in various lymphoid tissues. MC-LR further was found to significantly enhance the levels of osteoclastogenic cytokines (IL-6, IL-17 and TNF-α) along with simultaneously decreasing the levels of anti-osteoclastogenic cytokines (IL-10 and IFN-γ). Taken together, our study for the first time establishes a direct link between MC-LR intake and enhanced bone loss thereby giving a strong impetus to the naïve field of "osteo-toxicology", to delineate the effects of various toxins (including cyanotoxins) on bone health.

Immunoporosis: Immunology of Osteoporosis-Role of T Cells

The role of immune system in various bone pathologies, such as osteoporosis, osteoarthritis, and rheumatoid arthritis is now well established. This had led to the emergence of a modern field of systems biology called as osteoimmunology, an integrated research between fields of immunology and bone biology under one umbrella. Osteoporosis is one of the most common inflammatory bone loss condition with more than 200 million individuals affected worldwide. T helper (Th) cells along with various other immune cells are major players involved in bone homeostasis. In the present review, we specifically discuss the role of various defined T lymphocyte subsets (Th cells comprising Th1, Th2, Th9, Th17, Th22, regulatory T cells, follicular helper T cells, natural killer T cells, γδ T cells, and CD8⁺ T cells) in the pathophysiology of osteoporosis. The study of the specific role of immune system in osteoporosis has now been proposed by our group as “immunoporosis: the immunology of osteoporosis” with special emphasis on the role of various subsets of T lymphocytes. The establishment of this new field had been need of the hour due to the emergence of novel roles of various T cell lymphocytes in accelerated bone loss observed during osteoporosis. Activated T cells either directly or indirectly through the secretion of various cytokines and factors modulate bone health and thereby regulate bone remodeling. Several studies have summarized the role of inflammation in pathogenesis of osteoporosis but very few reports had delineated the precise role of various T cell subsets in the pathobiology of osteoporosis. The present review thus for the first time clearly highlights and summarizes the role of various T lymphocytes in the development and pathophysiology of osteoporosis, giving birth to a new field of biology termed as “immunoporosis”. This novel field will thus provide an overview of the nexus between the cellular components of both bone and immune systems, responsible for the observed bone loss in osteoporosis. A molecular insight into the upcoming and novel field of immunoporosis would thus leads to development of innovative approaches for the prevention and treatment of osteoporosis.

Bacillus clausii inhibits bone loss by skewing Treg-Th17 cell equilibrium in postmenopausal osteoporotic mice model

OBJECTIVES

Postmenopausal osteoporosis is one of most commonly occurring skeletal diseases leading to bone loss and fragility. Probiotics have been associated with various immunomodulatory properties and thus can be exploited to enhance bone health. In the present study, we report, to our knowledge for the first time, that oral administration of Bacillus clausii (BC) in postmenopausal osteoporotic (OVX) mice model enhances bone health.

METHODS

BC was selected as probiotic of choice due to its established immunomodulatory properties. BC skews the Treg-Th17 cell balance in vivo by inhibiting osteoclastogenic Th17 cells and promoting antiosteoclastogenic Treg cell development in postmenopausal osteoporotic mice. Mice were divided into three groups (sham, OVX, and OVX + BC), and BC was administered orally in drinking water for 6 wk post-ovariectomy. At the end of experiment, mice were sacrificed and bones were analyzed for various parameters, along with lymphoid tissues for Treg-Th17 cells and serum cytokines.

RESULTS

We observed that BC administration enhanced bone health. This effect of BC administration was found due to skewing of Treg-Th17 cell balance (enhanced Treg and decreased Th17 cells) in vivo. BC administration reduced levels of proinflammatory cytokines (interleukin [IL]-6, IL-17, IFN-γ and tumor necrosis factor-α) and increased levels of anti-inflammatory cytokine (IL-10).

CONCLUSIONS

The present study strongly supports and establishes the osteoprotective potential of BC leading to enhanced bone health in postmenopausal osteoporotic mice model.