Suboptimal Level of Bone-Forming Cells in Advanced Cirrhosis are Associated with Hepatic Osteodystrophy

Fragility spinal fractures among cirrhotic liver transplant candidates in Croatia

INTRODUCTION

Existing data on fragility spinal fractures prevalence in liver transplant candidates are scarce and inconsistent. This may be due to other comorbidities, besides hepatic osteodystrophy (HO), that contribute to bone loss and fragility fracture prevalence in chronic liver disease (CLD).

OBJECTIVES

The aim of this study was to investigate the prevalence of spinal thoracic and lumbar fragility fractures among cirrhotic, non-chronic kidney disease (CKD), non-diabetic liver transplant candidates and to explore their relationship with clinical characteristics, laboratory markers and dual-energy x-ray absorptiometry (DXA) results.

MATERIAL AND METHODS

This cross-sectional observational study was conducted at Merkur University Hospital, Croatia, between February 2019 and May 2023. Adult patients with liver cirrhosis referred for liver transplantation were included. Patients with acute infection, CKD, diabetes mellitus, malignancies, inflammatory bone diseases and those on corticosteroid or antiresorptive therapy were excluded. Clinical, laboratory and radiological assessment was carried out and patients were accordingly allocated into non-fractured and fractured group for the purpose of statistical analysis.

RESULTS

A total of 90 patients were included in the study. There was 123 fractures, 87 (70.7 %) in the thoracic and 36 (29.3 %) in the lumbar region. Eighty-nine (72.4 %) fractures were grade 1, 31 (25.2 %) were grade 2 and 3 (2.4 %) were grade 3. Patients in the fractured group were significantly older (p < 0.001). No significant differences between fractured and non-fractured group according to laboratory and DXA parameters were noted. Subgroup with lumbar fractures had significantly lower bone mineral density values at L1-L4 region. Statistically significant negative correlation between bone specific alkaline phosphatase (BALP) and hip total BMD (rho = -0.414, p < 0.001) and spine total BMD (rho = -0.258, p = 0.014) values was found.

CONCLUSION

Present study confirmed detrimental impact of CLD and HO on bone strength. DXA measurement correlated with the presence of lumbar fragility fractures. A combination of standard X-ray imaging and DXA is needed for adequate bone evaluation in pretransplant period and BALP could be useful for detecting HO in CLD. Searching for other risk factors and implementing bone turnover markers and additional imaging techniques for bone loss evaluation in liver transplant candidates is needed.

Fibroblast growth factor 23 and its role in bone diseases

Fibroblast growth factor 23 (FGF23) has been casually linked to numerous hypophosphatemic bone diseases, however connection with bone loss or fragility fractures is still a matter of debate. The purpose of this review is to explore and summarise the known actions of FGF23 in various pathological bone conditions. Besides implication in bone mineralisation, elevated FGF23 showed a pathological effecton bone remodelling, primarily by inhibiting osteoblast function. Unlike the weak association with bone mineral density, high values of FGF23 have been connected with fragility fracture prevalence. This review shows that its effects on bone are concomitantly present on multiple levels, affecting both qualitative and quantitative part of bone strength, eventually leading to impaired bone strength and increased tendency of fractures. Recognising FGF23 as a risk factor for the development of bone diseases and correcting its levels could lead to the reduction of morbidity and mortality in specific groups of patients.

Novel insights into osteocyte and inter-organ/tissue crosstalk

Osteocyte, a cell type living within the mineralized bone matrix and connected to each other by means of numerous dendrites, appears to play a major role in body homeostasis. Benefiting from the maturation of osteocyte extraction and culture technique, many cross-sectional studies have been conducted as a subject of intense research in recent years, illustrating the osteocyte-organ/tissue communication not only mechanically but also biochemically. The present review comprehensively evaluates the new research work on the possible crosstalk between osteocyte and closely situated or remote vital organs/tissues. We aim to bring together recent key advances and discuss the mutual effect of osteocyte and brain, kidney, vascular calcification, muscle, liver, adipose tissue, and tumor metastasis and elucidate the therapeutic potential of osteocyte.

Bile Acid Network and Vascular Calcification-Associated Diseases: Unraveling the Intricate Connections and Therapeutic Potential

Bile acids play a crucial role in promoting intestinal nutrient absorption and biliary cholesterol excretion, thereby protecting the liver from cholesterol accumulation and bile acid toxicity. Additionally, bile acids can bind to specific nuclear and membrane receptors to regulate energy expenditure and specific functions of particular tissues. Vascular calcification refers to the pathological process of calcium-phosphate deposition in blood vessel walls, which serves as an independent predictor for cardiovascular adverse events. In addition to aging, this pathological change is associated with aging-related diseases such as atherosclerosis, hypertension, chronic kidney disease, diabetes mellitus, and osteoporosis. Emerging evidence suggests a close association between the bile acid network and these aforementioned vascular calcification-associated conditions. Several bile acids have been proven to participate in calcium-phosphate metabolism, affecting the transdifferentiation of vascular smooth muscle cells and thus influencing vascular calcification. Targeting the bile acid network shows potential for ameliorating these diseases and their concomitant vascular calcification by regulating pathways such as energy metabolism, inflammatory response, oxidative stress, and cell differentiation. Here, we present a summary of the metabolism and functions of the bile acid network and aim to provide insights into the current research on the profound connections between the bile acid network and these vascular calcification-associated diseases, as well as the therapeutic potential.

Nestin+ Mesenchymal Stromal Cells Fibrotic Transition Mediated by CD169+ Macrophages in Bone Marrow Chronic Graft-versus-Host Disease

Chronic graft-versus-host disease (cGVHD) involves multiple organs, but little is known about bone marrow (BM) alterations caused by cGVHD. In mice and humans, we found that cGVHD is associated with BM fibrosis resulting in T cell infiltration, IgG deposition, and hematopoietic dysfunction. Macrophages and Nestin+ mesenchymal stromal cells (MSCs) participated in the process of BM fibrosis during BM cGVHD development. BM macrophage numbers were significantly increased in mice and humans with BM fibrosis associated with cGVHD. Amplified macrophages produced TGF-β1, which recruited Nestin+ MSCs forming clusters, and Nestin+ MSCs later differentiated into fibroblasts, a process mediated by increased TGF-β/Smad signaling. TLR4/MyD88-mediated activation of endoplasmic reticulum (ER) stress in macrophages is associated with fibrosis by increasing Nestin+ MSC migration and differentiation into fibroblasts. Depletion of macrophages by clodronate-containing liposomes and inhibition of ER stress by 4-phenylbutyric acid reversed BM fibrosis by inhibiting fibroblast differentiation. These studies provide insights into the pathogenesis of BM fibrosis during cGVHD development.

Seropositive for hepatitis B and C viruses is associated with the risk of decreased bone mineral density in adults: An analysis of studies from the NHANES database

Background

Some studies had reported that patients with viral hepatitis are at increased risk of reduced bone mineral density and even osteoporosis. However, the interaction between reduced bone mineral density (BMD) and viral hepatitis remains inconclusive. Therefore, our study collected hepatitis test results and bone mineral density from respondents in the NHANES database. The aim of this study was to investigate whether there is an association between hepatitis and a decrease in bone mineral density.

Methods

The respondents with both hepatitis- and BMD-related indicators from the NHANES database in the United States from 2005-2010, 2013-2014, to 2017-2020 were collected for this study. BMD were compared between respondents who were positive and negative for respondents related to hepatitis B and C. BMD was measured using dual-energy X-ray absorptiometry of the femur and lumbar spine. Finally, multiple regression analysis was performed between hepatitis B surface antigen (HBsAg) and hepatitis C RNA (HCV-RNA) and BMD in the respondents.

Results

A total of 15,642 respondents were included in the hepatitis B surface antigen-related survey. Of these, 1,217 respondents were positive for hepatitis B surface antigen. A total of 5111 hepatitis C RNA-related responders were included. Hepatitis C RNA-positive had 268 respondents. According to the results of the multiple regression analysis, the femoral BMD was significantly lower in HBsAg (+) respondents compared to HBsAg (-) respondents: -0.018 (-0.026, -0.009) (P < 0.01). Moreover, spinal BMD was significantly lower in HBsAg (+) respondents compared to HBsAg (-) respondents: -0.020 (-0.030, -0.010) (P < 0.01). According to the results of multiple regression analysis for hepatitis C RNA, HCV-RNA (+) respondents had significantly lower BMD compared to HCV-RNA (-) respondents: -0.043 (-0.059, -0.026) (P < 0.01).

Conclusion

During the analysis of respondents in the NHANES database in the United States, positive tests for hepatitis B surface antigen and hepatitis C RNA were found to be associated with a reduction in BMD. Positive serology for these hepatitis indicators may increase the risk of reduced BMD. Of course, this conclusion still needs to be further confirmed by more large clinical trials.

CEACAM-1 Induced CSF3-receptor Downregulation in Bone Marrow Associated With Refractory Neutropenia in Advanced Cirrhosis

BACKGROUND AND AIMS

Cirrhosis patients exhibit cytopenia, and, at times refractory neutropenia to granulocyte colony-stimulating factor (G-CSF), which acts through the CSF3-receptor (CSF3R), and changes in CSF3R can affect the response. We conducted this study to assess the CSF3R status and its relevance in cirrhotic patients.

METHODS

Cirrhotic patients (n=127) and controls (n=26) with clinically indicated bone marrow (BM) examination were studied. BM assessment was done by qRT-PCR and immunohistochemistry (IHC) for CSF3R. Circulating G-CSF, CSF3R, and carcinoembryonic antigen cell adhesion molecule-1 (CEACAM1) were measured. BM hematopoietic precursor cells and their alterations were examined by flow cytometry. The findings were validated in liver cirrhosis patients who received G-CSF for severe neutropenia.

RESULTS

The mean age was 48.6±13.4 years, and 80.3% were men. Circulatory CSF3R reduction was noted with the advancement of cirrhosis, and confirmed by qRT-PCR and IHC in BM. CSF3R decline was related to decreased hematopoietic stem cells (HSCs) and downregulation of CSF3R in the remaining HSCs. Cocultures confirmed that CEACAM1 led to CSF3R downregulation in BM cells by possible lysosomal degradation. Baseline low peripheral blood-(PB)-CSF3R also predisposed development of infections on follow-up. Decreased CSF3R was also associated with nonresponse to exogenous G-CSF treatment of neutropenia.

CONCLUSIONS

Advanced liver cirrhosis was associated with low CSF3R and high CEACAM1 levels in the BM and circulation, making patients prone to infection and inadequate response to exogenous G-CSF.

Defects in energy metabolism are associated with functional exhaustion of bone marrow mesenchymal stem cells in cirrhosis

OBJECTIVES

Cellular and functional exhaustion of bone marrow mesenchymal stem cells (BM-MSC) is significantly associated with the loss of HSCs and hepatic osteodystrophy in cirrhosis. The molecular mechanisms underlying the dysfunction of BM-MSCs are not well understood. We investigated the underlying mechanisms of cellular and functional exhaustion of BM-MSCs in cirrhosis.

METHODS

The MSCs were isolated retrospectively from bone marrow of decompensated alcoholic cirrhosis patients {(Trial registration: ClinicalTrials.gov NCT01902511) (n=10; MELD=16.2±2.3; CTP=8.7±2.3)} and age and gender-matched healthy controls (n=8). Global gene expression profile of healthy bone marrow MSCs (hBM-MSCs) and cirrhosis patients BM-MSCs (cBM-MSCs) were done by mRNA sequencing. XFe24-bioanalyzer analyzed the bioenergetic potential of cells. Level of different cytokines and growth factors in BM-plasma and MSCs secretome were analyzed by Luminex-based bead array.

RESULTS

Analysis of differentially expressed genes showed significant (P<0.01) up-regulation of genes associated with ubiquitination and catabolism of proteins; TNF signaling, insulin resistance, and down-regulation of genes associated with DNA repair, protein processing, cell cycle, and mitochondrial respiration in cBM-MSCs in comparison to hBM-MSCs. Compared to hBM-MSCs, cBM-MSCs showed a significant defect in glycolysis due to insulin resistance and poor glucose uptake (P=0.002). This led to compromised self-renewal capacity and cellular loss of MSCs in cirrhosis. cBM-MSCs also showed a significant impairment in Oxidative phosphorylation (OXPHOS) due to mitochondrial dysfunction leading to defects in the osteogenic differentiation with early aging and senescence.

CONCLUSION

Compromised energy metabolism due to inflammatory and metabolic stress-induced insulin resistance underlies the cellular and functional exhaustion of BM-MSCs in cirrhosis.

Nutrition in Chronic Liver Disease: Consensus Statement of the Indian National Association for Study of the Liver

Malnutrition and sarcopenia are common in patients with chronic liver disease and are associated with increased risk of decompensation, infections, wait-list mortality and poorer outcomes after liver transplantation. Assessment of nutritional status and management of malnutrition are therefore essential to improve outcomes in patients with chronic liver disease. This consensus statement of the Indian National Association for Study of the Liver provides a comprehensive review of nutrition in chronic liver disease and gives recommendations for nutritional screening and treatment in specific clinical scenarios of malnutrition in cirrhosis in adults as well as children with chronic liver disease and metabolic disorders.

Association of Bone Metabolism with Fatty Liver Disease in the Elderly in Japan: A Community-based Study

Objective With the aging of society, both osteoporosis and fatty liver disease (FLD) are becoming important issues. However, the relationship between osteoporosis and FLD remains controversial. We investigated the association between bone metabolism and FLD in a Japanese community in a cross-sectional study. Methods A total of 1,020 participants were enrolled in a health survey. FLD was diagnosed by ultrasonography. Bone metabolism was evaluated based on bone mineral density (BMD), which was assessed using dual-energy X-ray absorptiometry, and with the bone formation index (total type I procollagen N-terminal propeptide/bone-alkaline phosphatase ratio; P1NP/BAP ratio) and the bone resorption index (crosslinked N-telopeptide of type I collagen/tartrate-resistant acid phosphatase-5b ratio; NTx/TRACP-5b ratio) calculated from serum bone turnover markers. Results The BMD (percentage of the young adult mean) was the same level in both male and female participants with and without FLD. Both men and women showed an age-dependent decrease in their bone formation index and bone resorption index values. Men of ≥70 years of age and women of 60-69 years of age with FLD had significantly lower bone formation index values and higher bone resorption index values. However, similar findings were not seen in women of ≥70 years of age. Conclusion Although the BMD levels were the same, regardless of the presence or absence of FLD, elderly participants with FLD showed decreased bone formation and increased bone resorption, with sex differences. Because our results suggest that FLD in elderly individuals is detrimental for bone metabolism, and that it leads to bone loss and osteoporosis, further studies using a cohort population are warranted.

Serum levels of sclerostin reflect altered bone microarchitecture in patients with hepatic cirrhosis

Background

Patients with hepatic cirrhosis are at increased risk of bone loss. Recent work on areal bone mineral density has reported contradictory findings. As the assessment of bone microarchitecture is complex, a search was made for correlations with new serum markers of bone turnover. Current data on serum sclerostin levels in patients with increased fracture risk are divergent and to date only one study has examined patients with hepatic cirrhosis. Therefore, the aim of this study was to evaluate serum sclerostin levels and to test for correlations with microarchitecture.

Methods

This study was performed in 32 patients with recently diagnosed hepatic cirrhosis and 32 controls. The parameters of bone microarchitecture were assessed by high-resolution peripheral quantitative computed tomography. Sclerostin was detected via a new ELISA that detects the active receptor interaction site at loop 2 of the sclerostin core region.

Results

Sclerostin levels were slightly, but not significantly lower in the patient group, compared to controls. In contrast, patients with alcoholic liver cirrhosis had significantly lower levels than the controls. A significant correlation with areal bone mineral density (BMD) and trabecular microarchitecture was observed in the patient group. However, there was hardly any correlation between sclerostin and bone microarchitecture in the controls.

Conclusion

In hepatic cirrhosis, sclerostin is related to altered bone microarchitecture and lower areal BMD. In alcoholic liver disease, low sclerostin concentrations were seen.

Compromised bone strength in patients with alcoholic liver cirrhosis

Osteoporosis and/or osteopenia are frequently observed complications in alcoholic liver disease patients, especially in its irreversible stage (alcoholic liver cirrhosis - ALC). Current literature review regarding osteoporosis incidence increased fracture risk, bone mineral density changes, micro-structural alteration and pathogenetic mechanisms leading to ALC - induced decrease in bone quality is presented. It has been reported that osteoporosis is influenceing significant number of ALC patients, with particular accent on lumbar spine, as most commonly affected skeletal site. Several risk factors and ethio-pathogenic mechanisms have been associated with the loss of bone mineral density, in patients with ALC and other cirrhosis. Certain authors claim that dominant mechanism in ALC-induced bone loss is decrease in bone formation and osteoblastic function, while other results suggest increased bone remodeling as underlying cause of increased bone fragility in ALC patients. Increased bone fragility and susceptibility to osteoporotic fractures significantly affect life expectancy and quality of life in patients with ALC. Thus, osteological screening and individual fracture risk assessment are highly recommended for all patients with alcoholic liver cirrhosis.

Bone disease following solid organ transplantation: A narrative review and recommendations for management from The European Calcified Tissue Society

INTRODUCTION

Solid organ transplantation is an established therapy for end-stage organ failure. Both pre-transplantation bone disease and immunosuppressive regimens result in rapid bone loss and increased fracture rates.

METHODS

The European Calcified Tissue Society (ECTS) formed a working group to perform a systematic review of existing literature on the consequences of end-stage kidney, liver, heart, and lung disease on bone health. Moreover, we assessed the characteristics of post-transplant bone disease and the skeletal effects of immunosuppressive agents and aimed to provide recommendations for the prevention and treatment of transplantation-related osteoporosis.

RESULTS

Characteristics of bone disease may differ depending on the organ that fails, but patients awaiting solid organ transplantation frequently depict a wide spectrum of bone and mineral abnormalities. Common features are a decreased bone mass and impaired bone strength with consequent high fracture risk, all of which are aggravated in the early post-transplantation period.

CONCLUSION

Both the underlying disease leading to end-stage organ failure and the immunosuppression regimens implemented after successful organ transplantation have detrimental effects on bone mass, quality and strength. Given existing ample data confirming the high frequency of bone disease in patients awaiting solid organ transplantation, we recommend that all transplant candidates should be assessed for osteoporosis and fracture risk and, if indicated, treated before and after transplantation. Since bone loss in the early post-transplantation period occurs in virtually all solid organ recipients and is associated with glucocorticoid administration, the goal should be to use the lowest possible dose and to taper and withdraw glucocorticoids as early as possible.

Hepatic Osteodystrophy-Molecular Mechanisms Proposed to Favor Its Development

Almost all patients with chronic liver diseases (CLD) show altered bone metabolism. Depending on the etiology, this manifests in a severe osteoporosis in up to 75% of the affected patients. Due to high prevalence, the generic term hepatic osteodystrophy (HOD) evolved, describing altered bone metabolism, decreased bone mineral density, and deterioration of bone structure in patients with CLD. Once developed, HOD is difficult to treat and increases the risk of fragility fractures. Existing fractures affect the quality of life and, more importantly, long-term prognosis of these patients, which presents with increased mortality. Thus, special care is required to support the healing process. However, for early diagnosis (reduce fracture risk) and development of adequate treatment strategies (support healing of existing fractures), it is essential to understand the underlying mechanisms that link disturbed liver function with this bone phenotype. In the present review, we summarize proposed molecular mechanisms favoring the development of HOD and compromising the healing of associated fractures, including alterations in vitamin D metabolism and action, disbalances in transforming growth factor beta (TGF-β) and bone morphogenetic protein (BMP) signaling with histone deacetylases (HDACs) as secondary regulators, as well as alterations in the receptor activator of nuclear factor kappa B ligand (RANKL)–osteoprotegerin (OPG) system mediated by sclerostin. Based on these mechanisms, we give an overview on the limitations of early diagnosis of HOD with established serum markers.