Osteoprotegerin is a receptor for the cytotoxic ligand TRAIL

Targeting anti-apoptotic mechanisms in tumour cells: Strategies for enhancing Cancer therapy

Anti-cancer drug's cytotoxicity is determined by their ability to induce predetermined cell demise, commonly called apoptosis. The cancer-causing cells are able to evade cell death, which has been affiliated with both malignancy as well as resistance to cancer treatments. In order to avoid cell death, cancerous tumour cells often produce an abundance of anti-apoptotic proteins, becoming "dependent" on them. Consequently, protein inhibitors of cell death may prove to be beneficial as pharmacological targets for the future creation of cancer therapies. This article examines the molecular routes of apoptosis, its clinical manifestations, anti-cancer therapy options that target the intrinsic mechanism of apoptosis, proteins that prevent cell death, and members of the B-lymphoma-2 subset. In addition, novel approaches to cell death are highlighted, including how curcumin mitigates chemotherapy-induced apoptosis in healthy tissues and the various ways melatonin modifies apoptosis to improve cancer treatment efficacy, particularly through the TNF superfamily. Cancer treatment-induced increases in anti-apoptotic proteins lead to drug resistance; yet, ligands that trigger cell death by inhibiting these proteins are expected to improve chemotherapy's efficacy. The potential of frequency-modulated dietary phytochemicals as a cancer therapeutic pathway, including autophagy and apoptosis, is also explored. This approach may be more efficient than inhibition alone in overcoming drug resistance. Consequently, this method has the potential to allow for lower medication concentrations, reducing cytotoxicity and unwanted side effects.

Soluble form of tumor necrosis factor-related apoptosis-inducing ligand interacts with S100P protein

Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) is a therapeutically relevant protein belonging to the TNF superfamily. Both membrane-bound and soluble (sTRAIL) forms of TRAIL affect innate and adaptive immune responses. We recently showed that soluble TNF binds specific members of the S100 family of multifunctional calcium-binding proteins, leading to suppression of its cytotoxic activity (Int. J. Mol. Sci. 2022, 23(24), 15,956). To test the ability of S100 proteins to affect sTRAIL functioning, we used surface plasmon resonance spectroscopy, intrinsic fluorescence, chemical crosslinking, molecular modeling, site-directed mutagenesis, cytotoxicity assay, and bioinformatics to study interaction of human sTRAIL with human non-fused S100 proteins. Of the 21 S100 proteins examined, only S100P protein showed specific interaction with sTRAIL characterized by equilibrium dissociation constant, Kd, reaching (0.16 ± 0.07) μM. sTRAIL monomer binds dimeric S100P strictly in the presence of Ca2+, while sTRAIL trimer interacts with S100P dimer regardless of Ca2+. Site-directed mutagenesis confirmed involvement of the 'hinge' and C-terminal regions of S100P in the sTRAIL recognition, consistent with the structural modeling results. Bioinformatic analysis indicates dysregulation of TRAIL and S100P in various neoplasms. S100P lowers cytotoxicity of sTRAIL against human fibrosarcoma HT-1080 cells. The suppression of proapoptotic sTRAIL signaling by S100P protein may contribute to oncogenic effects of the latter.

Prospects for γδ T cells and chimeric antigen receptor γδ T cells in cancer immunotherapy

γδ T cells, a type of specialized T cell, differ from alpha-beta T cells due to the presence of γ and δ chain surface T cell receptors. These receptors allow them to directly recognize and bind antigenic molecules without the requirement of attachment to MHC or APC antigen presentation. Given their intrinsic properties and functional versatility, γδ T cells are under intensive investigation as carriers for chimeric antigen receptor (CAR) in the context of cancer therapy. In this regard, γδ CAR-T cells have demonstrated great potential to overcome the limitations of antigen recognition with the help of dual antigen identification mechanisms. However, there are still technological challenges that need to be addressed. This discussion focuses on the research status and future development prospects of γδ T cells and γδ CAR-T cells, aiming to provide valuable insights for the follow-up research and practical application of γδ CAR-T cells.

CD95/Fas stoichiometry in future precision medicine

CD95, also known as Fas, belongs to the tumor necrosis factor (TNF) receptor superfamily. The main biological function of this receptor is to orchestrate and control the immune response since mutations in CD95 or deregulation of its downstream signaling pathways lead to auto-immunity and inflammation. Interestingly, more than twenty years ago, pioneer studies highlighted that like TNFR1, TRAILR1 or CD40, CD95 pre-associates at the plasma membrane in a ligand-independent fashion. This self-association occurs through a domain designated pre-ligand assembly domain or PLAD. Although the disruption of this pre-association prevents CD95 signaling, no drugs targeting this region have been generated because many questions remain on the stoichiometry and conformation of this receptor. Despite more than 40.000 publications, no crystal structure of CD95 alone or in combination with its ligand, CD95L, exists. Based on other TNFR members, we herein discuss the predicted conformation of CD95 at the plasma membrane and how these putative structures might account for the induction of the cell signaling pathways.

RANKL blockade inhibits cancer growth through reversing the tolerogenic profile of tumor-infiltrating (plasmacytoid) dendritic cells

BACKGROUND

Originally identified for its involvement in bone remodeling, accumulating data emerged in the past years indicating that receptor activator of nuclear factor κB ligand (RANKL) actually acts as a multifunctional soluble molecule that influences various physiological and pathological processes. Regarding its role in carcinogenesis, while direct effects on tumor cell behavior have been precisely characterized, the impact of the RANKL/RANK system (and its inhibition) on the intratumoral immune landscape remains unclear.

METHODS

After various in silico/in situ/in vitro analyses, the immunotherapeutic efficacy of RANKL blockade (alone and in combination with immune checkpoint inhibitors (anti-programmed cell death protein-1 (PD-1)) or doxorubicin/paclitaxel-based chemotherapy) was investigated using different syngeneic mouse models of triple-negative breast cancer (4T1, 67NR and E0771). Isolated from retrieved tumors, 14 immune cell (sub)populations, along with the activation status of antigen-presenting cells, were thoroughly analyzed in each condition. Finally, the impact of RANKL on the functionality of both dendritic cells (DC) and plasmacytoid dendritic cells (pDC) was determined.

RESULTS

A drastic tumor growth inhibition was reproductively observed following RANKL inhibition. Strikingly, this antitumor activity was not detected in immunocompromised mice, demonstrating its dependence on the adaptive immune responses and justifying the diverse enriched signatures linked to immune cell regulation/differentiation detected in RANKLhigh-expressing human neoplasms. Interestingly, neoadjuvant chemotherapy (but not PD-1 checkpoint inhibition) potentiated the anticancer effects of RANKL blockade by priming effector T cells and increasing their infiltration within the tumor microenvironment. Mechanistically, we highlighted that RANKL indirectly promotes regulatory T cell differentiation and suppressive function by inhibiting the mTOR signaling pathway on antigen-presenting cells.

CONCLUSIONS

Taken together, this study provides insight into the role of RANKL/RANK axis in immune tolerance, demonstrates the significant impact of RANKL-dependent impairment of T cell-DC/pDC crosstalk on tumor development and, ultimately, supports that this ligand could be an interesting actionable target for cancer immunotherapy.

Exploring the dynamic role of circulating soluble tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as a diagnostic and prognostic marker; a review

Tumor necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL) is a TNF superfamily cytokine primarily acknowledged for its ability to selectively induce apoptosis in cancer cells. Beyond its antitumor effects, recent literature emphasizes the pleiotropic functions of TRAIL in physiological states and acute/chronic non-malignant diseases indicating its potential to be a breakthrough in diagnostics. This review explores the current understanding of the dynamic role of circulating soluble TRAIL (sTRAIL) and its potential as both a diagnostic and prognostic marker. Multiple in vitro, in vivo, and clinical studies in a wide range of neoplastic and non-neoplastic diseases including infectious diseases have been carried out to explore the potential role of sTRAIL in disease pathogenesis and as well as the possibilities of using it as a diagnostic and prognostic marker. The expression of sTRAIL seems to be context-dependent suggesting further research, particularly towards establishing disease-specific cutoff values. However, the lack of standardization in the serum sTRAIL estimation and the absence of reference intervals remain significant barriers to its clinical application. Addressing these challenges is essential for using circulating sTRAIL as an accurate diagnostic and prognostic marker in clinical practice.

Osteoprotegerin secretion and its inhibition by RANKL in osteoblastic cells visualized using bioluminescence imaging

Bone remodeling is regulated by the interaction between receptor activator of nuclear factor kappa-B ligand (RANKL) and its receptor RANK on osteoblasts and osteoclasts, respectively. Osteoprotegerin (OPG) is secreted from osteoblasts and inhibits osteoclast differentiation by acting as a decoy receptor for RANKL. Despite its importance, the mechanism underlying the secretion of OPG remains poorly understood. Here, we applied a method of video-rate bioluminescence imaging using a fusion protein with Gaussia luciferase (GLase) and visualized the secretion of OPG from living mouse osteoblastic MC3T3-E1 cells. The bioluminescence imaging revealed that the secretion of OPG fused to GLase (OPG-GLase) occurred frequently and widely across the cell surface. Notably, co-expression of RANKL significantly reduced the secretion of OPG-GLase, indicating an inhibitory role of RANKL on OPG secretion within cells. Further imaging and biochemical analyses using deletion mutants of OPG and RANKL, as well as RANKL mutants that cause autosomal recessive osteopetrosis, demonstrated the essential role of protein-protein interaction between OPG and RANKL in the inhibition of OPG secretion. Treatment with proteasome inhibitors resulted in increased levels of OPG in both culture medium and cell lysates. However, the fold-increase of OPG was similar regardless of the presence or absence of RANKL, suggesting that the regulation of OPG secretion by RANKL is independent of proteasome activity. This report visualized the secretion of OPG from living cells and provided evidence for a novel intracellular inhibitory effect of RANKL on OPG secretion.

The Role of Osteoprotegerin in Breast Cancer: Genetic Variations, Tumorigenic Pathways, and Therapeutic Potential

INTRODUCTION

Osteoprotegerin (OPG), encoded by the TNFRSF11B gene, is linked to the development of breast cancer via several pathways, including interactions with the receptor activator of nuclear factor-κB (RANK) ligands, apoptosis-inducing proteins like TRAIL, and genetic variations such as single nucleotide polymorphisms (SNPs), directly altering gene expression. This review aims to investigate the role of OPG expression in breast cancer.

METHODS

A comprehensive literature search was conducted using PubMed Medline, Google Scholar, and ScienceDirect. Only full-text English publications from inception to September 2024 were included.

RESULTS

Studies have demonstrated that certain SNPs in the OPG gene, specifically rs3102735 and rs2073618, are linked to a higher risk of breast cancer development. Additionally, OPG's function as a TRAIL decoy receptor may inhibit the death of cancer cells. Furthermore, OPG in the serum and its interactions with BRCA mutations are being investigated for their potential influence on breast cancer progression. Studies have found that OPG promotes tumorigenesis by enhancing cell proliferation, angiogenesis, and aneuploidy in normal mammary epithelial cells. Moreover, OPG mediates the tumor-promoting effects of interleukin-1 beta and may serve as a biomarker for breast cancer risk, particularly in BRCA1 mutation carriers, through its role in dysregulated RANK signaling. Lastly, the use of recombinant OPG in mouse models has been found to exert anti-tumor effects.

CONCLUSIONS

In this review, the role of OPG in breast cancer is examined. OPG has a multifaceted role in breast cancer tumorigenesis and exerts its effects through genetic variations (SNPs), interactions with TNF-related apoptosis-inducing ligand (TRAIL), and the modulation of the pro-tumorigenic microenvironment effects of angiogenesis, cell survival, and metastasis. Additionally, OPG's dual role as a tumor suppressor and promoter serves as a possible therapeutic target to enhance apoptosis, limit bone metastasis, and modulate the tumor microenvironment. Whilst much is now known, further studies are necessary to fully delineate the role of OPG.

Osteoprotegerin as an Emerging Biomarker of Carotid Artery Stenosis? A Scoping Review with Meta-Analysis

Objective: In developed countries, stroke is the fifth cause of death, with a high mortality rate, and with recovery to normal neurological function in one-third of survivors. Atherosclerotic occlusive disease of the extracranial part of the internal carotid artery and related embolic complications are common preventable causes of ischemic stroke (IS), attributable to 7-18% of all first-time cases. Osteoprotegerin (OPG), a soluble member of the tumor necrosis factor receptor (TNFR) superfamily, is considered a modulator of vascular calcification linked to vascular smooth muscle cell proliferation and collagen production in atherosclerotic plaques. Therefore, OPG emerges as a potential biomarker (BM) of calcified carotid plaques and carotid artery stenosis (CAS). Methods: We performed a literature search of PubMed on OPG in CAS and atherosclerosis published until 2024. Results: Increased levels of serum OPG were reported in both patients with symptomatic and asymptomatic CAS, and higher values were observed in those with unstable atherosclerotic plaques. Notably, increased OPG levels were observed regardless of the location of atherosclerosis, including coronary and other peripheral arteries. In addition, chronic kidney disease, the most significant confounder disturbing the association between vascular damage and circulating OPG levels, decreases the usefulness of OPG as a BM in CAS. Conclusions: Osteoprotegerin may be considered an emerging BM of global rather than cerebrovascular atherosclerosis. Its diagnostic significance in identifying patients with asymptomatic CAS and their monitoring is limited.

Unraveling the Intricacies of OPG/RANKL/RANK Biology and Its Implications in Neurological Disorders-A Comprehensive Literature Review

The OPG/RANKL/RANK framework, along with its specific receptors, plays a crucial role in bone remodeling and the functioning of the central nervous system (CNS) and associated disorders. Recent research and investigations provide evidence that the components of osteoprotegerin (OPG), receptor activator of NF-kB ligand (RANKL), and receptor activator of NF-kB (RANK) are expressed in the CNS. The CNS structure encompasses cells involved in neuroinflammation, including local macrophages, inflammatory cells, and microglia that cross the blood-brain barrier. The OPG/RANKL/RANK trio modulates the neuroinflammatory response based on the molecular context. The levels of OPG/RANKL/RANK components can serve as biomarkers in the blood and cerebrospinal fluid. They act as neuroprotectants following brain injuries and also participate in the regulation of body weight, internal body temperature, brain ischemia, autoimmune encephalopathy, and energy metabolism. Although the OPG/RANKL/RANK system is primarily known for its role in bone remodeling, further exploring deeper into its multifunctional nature can uncover new functions and novel drug targets for diseases not previously associated with OPG/RANKL/RANK signaling.

Immunomodulatory Functions of TNF-Related Apoptosis-Inducing Ligand in Type 1 Diabetes

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF protein superfamily and was initially identified as a protein capable of inducing apoptosis in cancer cells. In addition, TRAIL can promote pro-survival and proliferation signaling in various cell types. Subsequent studies have demonstrated that TRAIL plays several important roles in immunoregulation, immunosuppression, and immune effector functions. Type 1 diabetes (T1D) is an autoimmune disease characterized by hyperglycemia due to the loss of insulin-producing β-cells, primarily driven by T-cell-mediated pancreatic islet inflammation. Various genetic, epigenetic, and environmental factors, in conjunction with the immune system, contribute to the initiation, development, and progression of T1D. Recent reports have highlighted TRAIL as an important immunomodulatory molecule with protective effects on pancreatic islets. Experimental data suggest that TRAIL protects against T1D by reducing the proliferation of diabetogenic T cells and pancreatic islet inflammation and restoring normoglycemia in animal models. In this review, we aimed to summarize the consequences of TRAIL action in T1D, focusing on and discussing its signaling mechanisms, role in the immune system, and protective effects in T1D.

Correlating Material Properties to Osteoprotegerin Expression on Nanoparticulate Mineralized Collagen Glycosaminoglycan Scaffolds

Precision material design directed by cell biological processes represents a frontier in developing clinically translatable regenerative technologies. While understanding cell-material interactions on multipotent progenitor cells yields insights on target tissue differentiation, equally if not more important is the quantification of indirect multicellular interactions. In this work, the relationship of two material properties, phosphate content and stiffness, of a nanoparticulate mineralized collagen glycosaminoglycan scaffold (MC-GAG) in the expression of an endogenous anti-osteoclastogenic secreted protein, osteoprotegerin (OPG) by primary human mesenchymal stem cells (hMSCs) is evaluated. The phosphate content of MC-GAG requires the type III sodium phosphate symporter PiT-1/SLC20A1 for OPG expression, correlating with β-catenin downregulation, but is independent of the effects of phosphate ion on osteogenic differentiation. Using three stiffness MC-GAG variants that do not differ significantly by osteogenic differentiation, it is observed that the softest material elicited ≈1.6-2 times higher OPG expression than the stiffer materials. Knockdown of the mechanosensitive signaling axis of YAP, TAZ, β-catenin and combinations thereof in hMSCs on MC-GAG demonstrates that β-catenin downregulation increases OPG expression by 1.5-fold. Taken together, these data constitute a roadmap for material properties that can used to suppress osteoclast activation via osteoprotegerin expression separately from the anabolic processes of osteogenesis.

Chemical synthetic approaches to mimic the TRAIL: promising cancer therapeutics

Apoptosis is programmed cell death that eliminates undesired cells to maintain homeostasis in metazoan. Aberration of this process may lead to cancer genesis. The tumor necrosis factor related apoptosis inducing ligand (TRAIL) induces apoptosis in cancer cells after ligation with death receptors (DR4/DR5) while sparing most normal cells. Therefore, strategies to induce apoptosis in cancer cells by mimicking the TRAIL emerge as a promising therapeutic tool. Hence, approaches are taken to develop TRAIL/DR-based cancer therapeutics. The recombinant soluble TRAIL (rhTRAIL) and death receptor agonistic antibodies were produced and tested pre-clinically and clinically. Pre-clinical and clinical trial data demonstrate that these therapeutics are safe and relatively well tolerated. But some of these therapeutics failed to exert adequate efficacy in clinical settings. Besides these biotechnologically derived therapeutics, a few chemically synthesized therapeutics are reported. Some of these therapeutics exert considerable efficacy in vitro and in vivo. In this review, we will discuss chemically synthesized TRAIL/DR-based therapeutics, their chemical and biological behaviour, design concepts and strategies that may contribute to further improvement of TRAIL/DR-based therapeutics.

Osteoprotegerin (OPG) and its ligands RANKL and TRAIL in falciparum, vivax and knowlesi malaria: correlations with disease severity, and B cell production of OPG

Osteoprotegerin (OPG) is a soluble decoy receptor for receptor activator of NF-ƙB ligand (RANKL) and TNF-related apoptosis-inducing ligand (TRAIL), and is increasingly recognised as a marker of poor prognosis in a number of diseases. Here we demonstrate that in Malaysian adults with falciparum and vivax malaria, OPG is increased, and its ligands TRAIL and RANKL decreased, in proportion to disease severity. In volunteers experimentally infected with P. falciparum and P. vivax, RANKL was suppressed, while TRAIL was unexpectedly increased, suggesting binding of OPG to RANKL prior to TRAIL. We also demonstrate that P. falciparum stimulates B cells to produce OPG in vitro, and that B cell OPG production is increased ex vivo in patients with falciparum, vivax and knowlesi malaria. Our findings provide further evidence of the importance of the OPG/RANKL/TRAIL pathway in pathogenesis of diseases involving systemic inflammation, and may have implications for adjunctive therapies. Further evaluation of the role of B cell production of OPG in host responses to malaria and other inflammatory diseases is warranted.

Osteoprotegerin in infection-induced acute inflammatory states in children

Background and aims

Osteoprotegerin (OPG) is a tumor necrosis factor receptor superfamily member which increases in chronic inflammation and is associated with altered bone turnover and cardiovascular complications. In this study, we investigated whether OPG increases during acute inflammatory states induced by infections in children and correlated its levels with other biomarkers.

Materials and methods

This is a prospective study that included 59 patients with documented bacterial infections, 20 with viral infections and 20 healthy controls. OPG, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and white blood cells (WBC) were measured.

Results

OPG serum levels were significantly increased during inflammation induced by a bacterial infection, compared to viral infection and controls (4.17 pmol/l (2.40-12.12) vs 3.2 (1.66-5.33) and 3 pmol/l (2.13-4.76), respectively, p < 0.001). In addition, OPG correlated well with CRP (rho = 0.428, p = 0.0011), ESR (rho = 0.3, p = 0.026), and WBC (rho = 0.266, p = 0.05) only in the group with bacterial infection. The sensitivity of CRP in detecting a bacterial infection was superior to OPG (67.3% vs 38.3%).

Conclusion

This study provides proof of concept that OPG increases differentially in bacterial infections, although with a lower sensitivity than CRP. Further studies are needed to define the role of OPG during the inflammatory states of infection in pediatric infections.

TNF-Related Apoptosis-Inducing Ligand: Non-Apoptotic Signalling

TNF-related apoptosis-inducing ligand (TRAIL or Apo2 or TNFSF10) belongs to the TNF superfamily. When bound to its agonistic receptors, TRAIL can induce apoptosis in tumour cells, while sparing healthy cells. Over the last three decades, this tumour selectivity has prompted many studies aiming at evaluating the anti-tumoral potential of TRAIL or its derivatives. Although most of these attempts have failed, so far, novel formulations are still being evaluated. However, emerging evidence indicates that TRAIL can also trigger a non-canonical signal transduction pathway that is likely to be detrimental for its use in oncology. Likewise, an increasing number of studies suggest that in some circumstances TRAIL can induce, via Death receptor 5 (DR5), tumour cell motility, potentially leading to and contributing to tumour metastasis. While the pro-apoptotic signal transduction machinery of TRAIL is well known from a mechanistic point of view, that of the non-canonical pathway is less understood. In this study, we the current state of knowledge of TRAIL non-canonical signalling.

Heparan sulfate promotes TRAIL-induced tumor cell apoptosis

TRAIL (TNF-related apoptosis-inducing ligand) is a potent inducer of tumor cell apoptosis through TRAIL receptors. While it has been previously pursued as a potential anti-tumor therapy, the enthusiasm subsided due to unsuccessful clinical trials and the fact that many tumors are resistant to TRAIL. In this report, we identified heparan sulfate (HS) as an important regulator of TRAIL-induced apoptosis. TRAIL binds HS with high affinity (KD = 73 nM) and HS induces TRAIL to form higher-order oligomers. The HS-binding site of TRAIL is located at the N-terminus of soluble TRAIL, which includes three basic residues. Binding to cell surface HS plays an essential role in promoting the apoptotic activity of TRAIL in both breast cancer and myeloma cells, and this promoting effect can be blocked by heparin, which is commonly administered to cancer patients. We also quantified HS content in several lines of myeloma cells and found that the cell line showing the most resistance to TRAIL has the least expression of HS, which suggests that HS expression in tumor cells could play a role in regulating sensitivity towards TRAIL. We also discovered that death receptor 5 (DR5), TRAIL, and HS can form a ternary complex and that cell surface HS plays an active role in promoting TRAIL-induced cellular internalization of DR5. Combined, our study suggests that TRAIL-HS interactions could play multiple roles in regulating the apoptotic potency of TRAIL and might be an important point of consideration when designing future TRAIL-based anti-tumor therapy.

Single-cell transcriptomics stratifies organoid models of metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing cause of morbidity with limited treatment options. Thus, accurate in vitro systems to test new therapies are indispensable. While recently, human liver organoid models have emerged to assess steatotic liver disease, a systematic evaluation of their translational potential is still missing. Here, we evaluated human liver organoid models of MASLD, comparatively testing disease induction in three conditions: oleic acid, palmitic acid, and TGF-β1. Through single-cell analyses, we find that all three models induce inflammatory signatures, but only TGF-β1 promotes collagen production, fibrosis, and hepatic stellate cell expansion. In striking contrast, oleic acid ameliorates fibrotic signatures and reduces the hepatic stellate cell population. Linking data from each model to gene expression signatures associated with MASLD disease progression further demonstrates that palmitic acid and TGF-β1 more robustly model inflammation and fibrosis. Our findings highlight the importance of stratifying MASLD organoid models by signatures of clinical disease progression, provide a single-cell reference to benchmark future organoid injury models, and allow us to study evolving steatohepatitis, fibrosis, and HSC susceptibility to injury in a dynamic, multi-lineage human in vitro system.

Plasma TNFRSF11B as a New Predictive Inflammatory Marker of Sepsis-ARDS with Endothelial Dysfunction

Inflammation plays an important role in the development of sepsis-acute respiratory distress syndrome (ARDS). Olink inflammation-related biomarker panels were used to analyze the levels of 92 inflammation-related proteins in plasma with sepsis-ARDS (n = 25) and healthy subjects (n = 25). There were significant differences in 64 inflammatory factors, including TNFRSF11B in sepsis-ARDS, which was significantly higher than that in controls. Functional analysis showed that TNFRSF11B was closely focused on signal transduction, immune response, and inflammatory response. The TNFRSF11B level in sepsis-ARDS plasma, LPS-induced mice, and LPS-stimulated HUVECs significantly increased. The highest plasma concentration of TNFRSF11B in patients with sepsis-ARDS was 10-20 ng/mL, and 10 ng/mL was selected to stimulate HUVECs. Western blot results demonstrated that the levels of syndecan-1, claudin-5, VE-cadherin, occludin, aquaporin-1, and caveolin-1 in TNFRSF11B-stimulated HUVECs decreased, whereas that of connexin-43 increased in TNFRSF11B-stimulated HUVECs. To the best of the authors' knowledge, this study was the first to reveal elevated TNFRSF11B in sepsis-ARDS associated with vascular endothelial dysfunction. In summary, TNFRSF11B may be a new potential predictive and diagnostic biomarker for vascular endothelium damage in sepsis-ARDS.

Heparan sulfate promotes TRAIL-induced tumor cell apoptosis

TRAIL (TNF-related apoptosis-inducing ligand) is a potent inducer of tumor cell apoptosis through TRAIL receptors. While it has been previously pursued as a potential anti-tumor therapy, the enthusiasm subsided due to unsuccessful clinical trials and the fact that many tumors are resistant to TRAIL. In this report we identified heparan sulfate (HS) as an important regulator of TRAIL-induced apoptosis. TRAIL binds HS with high affinity (KD = 73 nM) and HS induces TRAIL to form higher-order oligomers. The HS-binding site of TRAIL is located at the N-terminus of soluble TRAIL, which includes three basic residues. Binding to cell surface HS plays an essential role in promoting the apoptotic activity of TRAIL in both breast cancer and myeloma cells, and this promoting effect can be blocked by heparin, which is commonly administered to cancer patients. We also quantified HS content in several lines of myeloma cells and found that the cell line showing the most resistance to TRAIL has the least expression of HS, which suggests that HS expression in tumor cells could play a role in regulating sensitivity towards TRAIL. We also discovered that death receptor 5 (DR5), TRAIL and HS can form a ternary complex and that cell surface HS plays an active role in promoting TRAIL-induced cellular internalization of DR5. Combined, our study suggests that TRAIL-HS interactions could play multiple roles in regulating the apoptotic potency of TRAIL and might be an important point of consideration when designing future TRAIL-based anti-tumor therapy.

CD95 (Fas) and CD95L (FasL)-mediated non-canonical signaling pathways

Although the interaction of CD95L (also known as FasL) with its so-called death receptor CD95 (Fas) induces an apoptotic signal responsible for the elimination of infected and cancer cells and maintenance of tissue homeostasis, this receptor can also implement non apoptotic signaling pathways. This latter signaling is involved in metastatic dissemination in certain cancers and the severity of auto-immune disorders. The signaling complexity of this pair is increased by the fact that CD95 expression itself seems to contribute to oncogenesis via a CD95L-independent manner and, that both ligand and receptor might interact with other partners modulating their pathophysiological functions. Finally, CD95L itself can trigger cell signaling in immune cells rendering complex the interpretation of mouse models in which CD95 or CD95L are knocked out. Herein, we discuss these non-canonical responses and their biological functions.

TRAIL promotes the polarization of human macrophages toward a proinflammatory M1 phenotype and is associated with increased survival in cancer patients with high tumor macrophage content

Background

TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily that can either induce cell death or activate survival pathways after binding to death receptors (DRs) DR4 or DR5. TRAIL is investigated as a therapeutic agent in clinical trials due to its selective toxicity to transformed cells. Macrophages can be polarized into pro-inflammatory/tumor-fighting M1 macrophages or anti-inflammatory/tumor-supportive M2 macrophages and an imbalance between M1 and M2 macrophages can promote diseases. Therefore, identifying modulators that regulate macrophage polarization is important to design effective macrophage-targeted immunotherapies. The impact of TRAIL on macrophage polarization is not known.

Methods

Primary human monocyte-derived macrophages were pre-treated with either TRAIL or with DR4 or DR5-specific ligands and then polarized into M1, M2a, or M2c phenotypes in vitro. The expression of M1 and M2 markers in macrophage subtypes was analyzed by RNA sequencing, qPCR, ELISA, and flow cytometry. Furthermore, the cytotoxicity of the macrophages against U937 AML tumor targets was assessed by flow cytometry. TCGA datasets were also analyzed to correlate TRAIL with M1/M2 markers, and the overall survival of cancer patients.

Results

TRAIL increased the expression of M1 markers at both mRNA and protein levels while decreasing the expression of M2 markers at the mRNA level in human macrophages. TRAIL also shifted M2 macrophages towards an M1 phenotype. Our data showed that both DR4 and DR5 death receptors play a role in macrophage polarization. Furthermore, TRAIL enhanced the cytotoxicity of macrophages against the AML cancer cells in vitro. Finally, TRAIL expression was positively correlated with increased expression of M1 markers in the tumors from ovarian and sarcoma cancer patients and longer overall survival in cases with high, but not low, tumor macrophage content.

Conclusions

TRAIL promotes the polarization of human macrophages toward a proinflammatory M1 phenotype via both DR4 and DR5. Our study defines TRAIL as a new regulator of macrophage polarization and suggests that targeting DRs can enhance the anti-tumorigenic response of macrophages in the tumor microenvironment by increasing M1 polarization.

RANK pathway in cancer: underlying resistance and therapeutic approaches

Cancer remains one of the deadliest diseases despite advances in treatment. Metastatic cancers are the leading cause of death for advanced cancer patients. Those with advanced cancer with osteolytic-type bone metastases have a significantly lower quality of life. A novel treatment plan is needed now more than ever for breast cancer patients with bone metastases. There are shreds of evidence that cancer cells in the bloodstream interact with the bone microenvironment and that this interaction is a contributing component to breast cancer progression. Preventing any stage of this cycle can result in anti-metastasis effects. Since RANKL interacts with its receptor RANK and plays an important role in the vicious cycle, it has proven to be a successful therapeutic target in cancer treatment. As a result, we have presented a complete overview of the RANK pathway in cancer and discussed RANK signaling and tumor microenvironment, and potential therapeutic approaches in this review.

TRAIL and its receptors in cardiac diseases

Cardiovascular disease is a leading cause of death worldwide. Loss of cardiomyocytes that occurs during many types of damage to the heart such as ischemic injury and stress caused by pressure overload, diminishes cardiac function due to their limited regenerative capacity and promotes remodeling, which further damages the heart. Cardiomyocyte death occurs through two primary mechanisms, necrosis and apoptosis. Apoptosis is a highly regulated form of cell death that can occur through intrinsic (mitochondrial) or extrinsic (receptor mediated) pathways. Extrinsic apoptosis occurs through a subset of Tumor Necrosis Receptor (TNF) family receptors termed "Death Receptors." While some ligands for death receptors have been extensively studied in the heart, such as TNF-α, others have been virtually unstudied. One poorly characterized cardiac TNF related ligand is TNF-Related Apoptosis Inducing Ligand (TRAIL). TRAIL binds to two apoptosis-inducing receptors, Death Receptor (DR) 4 and DR5. There are also three decoy TRAIL receptors, Decoy Receptor (DcR) 1, DcR2 and osteoprotegerin (OPG). While TRAIL has been extensively studied in the cancer field due to its ability to selectively induce apoptosis in transformed cell types, emerging clinical evidence points towards a role for TRAIL and its receptors in cardiac pathology. This article will highlight our current understanding of TRAIL and its receptors in normal and pathological conditions in the heart.

Interleukin-23 Regulates Inflammatory Osteoclastogenesis via Activation of CLEC5A(+) Osteoclast Precursors

OBJECTIVE

To investigate the role of interleukin-23 (IL-23) in pathologic bone remodeling in inflammatory arthritis.

METHODS

In this study we investigated the role of IL-23 in osteoclast differentiation and activation using in vivo gene transfer techniques in wild-type and myeloid DNAX-activation protein 12-associating lectin-1 (MDL-1)-deficient mice, and by performing in vitro and in vivo osteoclastogenesis assays using spectral flow cytometry, micro-computed tomography analysis, Western blotting, and immunoprecipitation.

RESULTS

Herein, we show that IL-23 induces the expansion of a myeloid osteoclast precursor population and supports osteoclastogenesis and bone resorption in inflammatory arthritis. Genetic ablation of C-type lectin domain family member 5A, also known as MDL-1, prevents the induction of osteoclast precursors by IL-23 that is associated with bone destruction, as commonly observed in inflammatory arthritis. Moreover, osteoclasts derived from the bone marrow of MDL-1-deficient mice showed impaired osteoclastogenesis, and MDL-1-/- mice had increased bone mineral density.

CONCLUSION

Our data show that IL-23 signaling regulates the availability of osteoclast precursors in inflammatory arthritis that could be effectively targeted for the treatment of inflammatory bone loss in inflammatory arthritis.

TNF superfamily control of tissue remodeling and fibrosis

Fibrosis is the result of extracellular matrix protein deposition and remains a leading cause of death in USA. Despite major advances in recent years, there remains an unmet need to develop therapeutic options that can effectively degrade or reverse fibrosis. The tumor necrosis super family (TNFSF) members, previously studied for their roles in inflammation and cell death, now represent attractive therapeutic targets for fibrotic diseases. In this review, we will summarize select TNFSF and their involvement in fibrosis of the lungs, the heart, the skin, the gastrointestinal tract, the kidney, and the liver. We will emphasize their direct activity on epithelial cells, fibroblasts, and smooth muscle cells. We will further report on major clinical trials targeting these ligands. Whether in isolation or in combination with other anti-TNFSF member or treatment, targeting this superfamily remains key to improve efficacy and selectivity of currently available therapies for fibrosis.

Plasma TRAIL and ANXA1 in diagnosis and prognostication of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare vasculopathy, with high morbidity and mortality. The sensitivity of the current european society of cardiology/european respiratory society (ESC/ERS) risk assessment strategy may be improved by the addition of biomarkers related to PAH pathophysiology. Such plasma-borne biomarkers may also reduce time to diagnosis, if used as diagnostic tools in patients with unclear dyspnea, and in guiding treatment decisions. Plasma levels of proteins related to tumor necrosis factor (TNF), inflammation, and immunomodulation were analyzed with proximity extension assays in patients with PAH (n = 48), chronic thromboembolic pulmonary hypertension (PH; CTEPH, n = 20), PH due to left heart failure (HF) with preserved (HFpEF-PH, n = 33), or reduced (HFrEF-PH, n = 36) ejection fraction, HF without PH (n = 15), and healthy controls (n = 20). TNF-related apoptosis-inducing ligand (TRAIL) were lower in PAH versus the other disease groups and controls (p < 0.0082). In receiver operating characteristics analysis, TRAIL levels identified PAH from the other disease groups with a sensitivity of 0.81 and a specificity of 0.53 [area under the curve: 0.70; (95% confidence interval, CI: 0.61-0.79; p < 0.0001)]. In both single (p < 0.05) and multivariable Cox regression models Annexin A1 (ANXA1) [hazard ratio, HR: 1.0367; (95% CI: 1.0059-1.0684; p = 0.044)] and carcinoembryonic antigen-related cell adhesion molecule 8 [HR: 1.0603; (95% CI: 1.0004-1.1237; p = 0.0483)] were significant predictors of survival, adjusted for age, female sex and ESC/ERS-initial risk score. Low plasma TRAIL predicted PAH among patients with dyspnea and differentiated PAH from those with CTEPH, HF with and without PH; and healthy controls. Higher plasma ANXA1 was associated with worse survival in PAH. Larger multicenter studies are encouraged to validate our findings.

Emerging biologics for the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare pulmonary vascular disorder, wherein mean systemic arterial pressure (mPAP) becomes abnormally high because of aberrant changes in various proliferative and inflammatory signalling pathways of pulmonary arterial cells. Currently used anti-PAH drugs chiefly target the vasodilatory and vasoconstrictive pathways. However, an imbalance between bone morphogenetic protein receptor type II (BMPRII) and transforming growth factor beta (TGF-β) pathways is also implicated in PAH predisposition and pathogenesis. Compared to currently used PAH drugs, various biologics have shown promise as PAH therapeutics that elicit their therapeutic actions akin to endogenous proteins. Biologics that have thus far been explored as PAH therapeutics include monoclonal antibodies, recombinant proteins, engineered cells, and nucleic acids. Because of their similarity with naturally occurring proteins and high binding affinity, biologics are more potent and effective and produce fewer side effects when compared with small molecule drugs. However, biologics also suffer from the limitations of producing immunogenic adverse effects. This review describes various emerging and promising biologics targeting the proliferative/apoptotic and vasodilatory pathways involved in PAH pathogenesis. Here, we have discussed sotatercept, a TGF-β ligand trap, which is reported to reverse vascular remodelling and reduce PVR with an improved 6-minute walk distance (6-MWDT). We also elaborated on other biologics including BMP9 ligand and anti-gremlin1 antibody, anti-OPG antibody, and getagozumab monoclonal antibody and cell-based therapies. Overall, recent literature suggests that biologics hold excellent promise as a safe and effective alternative to currently used PAH therapeutics.

RANKL inhibition: a new target of treating diabetes mellitus?

Accumulating evidence demonstrates the link between glucose and bone metabolism. The receptor activator of nuclear factor-kB ligand (RANKL)/the receptor activator of NF-κB (RANK)/osteoprotegerin (OPG) axis is an essential signaling axis maintaining the balance between bone resorption and bone formation. In recent years, it has been found that RANKL and RANK are distributed not only in bone but also in the liver, muscle, adipose tissue, pancreas, and other tissues that may influence glucose metabolism. Some scholars have suggested that the blockage of the RANKL signaling may protect islet β-cell function and prevent diabetes; simultaneously, there also exist different views that RANKL can improve insulin resistance through inducing the beige adipocyte differentiation and increase energy expenditure. Currently, the results of the regulatory effect on glucose metabolism of RANKL remain conflicting. Denosumab (Dmab), a fully human monoclonal antibody that can bind to RANKL and prevent osteoclast formation, is a commonly used antiosteoporosis drug. Recent basic studies have found that Dmab seems to regulate glucose homeostasis and β-cell function in humanized mice or in vitro human β-cell models. Besides, some clinical data have also reported the glucometabolic effects of Dmab, however, with limited and inconsistent results. This review mainly describes the impact of the RANKL signaling pathway on glucose metabolism and summarizes clinical evidence that links Dmab and DM to seek a new therapeutic strategy for diabetes.

Colec12 and Trail signaling confine cranial neural crest cell trajectories and promote collective cell migration

BACKGROUND

Collective and discrete neural crest cell (NCC) migratory streams are crucial to vertebrate head patterning. However, the factors that confine NCC trajectories and promote collective cell migration remain unclear.

RESULTS

Computational simulations predicted that confinement is required only along the initial one-third of the cranial NCC migratory pathway. This guided our study of Colec12 (Collectin-12, a transmembrane scavenger receptor C-type lectin) and Trail (tumor necrosis factor-related apoptosis-inducing ligand, CD253) which we show expressed in chick cranial NCC-free zones. NCC trajectories are confined by Colec12 or Trail protein stripes in vitro and show significant and distinct changes in cell morphology and dynamic migratory characteristics when cocultured with either protein. Gain- or loss-of-function of either factor or in combination enhanced NCC confinement or diverted cell trajectories as observed in vivo with three-dimensional confocal microscopy, respectively, resulting in disrupted collective migration.

CONCLUSIONS

These data provide evidence for Colec12 and Trail as novel NCC microenvironmental factors playing a role to confine cranial NCC trajectories and promote collective cell migration.

Postdiagnosis circulating osteoprotegerin and TRAIL concentrations and survival and recurrence after a breast cancer diagnosis: results from the MARIE patient cohort

BACKGROUND

Experimental studies suggest a role for osteoprotegerin (OPG) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in mammary tumor development and progression. These biomarkers have been minimally investigated with respect to outcomes in breast cancer patients.

METHODS

OPG and TRAIL were evaluated in blood samples collected from 2459 breast cancer patients enrolled in the MARIE study, a prospective population-based patient cohort, at median of 129 days after diagnosis. Participants were between ages 50 and 74 at diagnosis and recruited from 2002 to 2005 in two regions of Germany. Follow-up for recurrence and mortality was conducted through June 2015. Delayed-entry Cox proportional hazards regression was used to assess associations between OPG and TRAIL with all-cause and breast cancer-specific mortality, and recurrence, both overall and by tumor hormone receptor status.

RESULTS

Median follow-up time was 11.7 years, with 485 deaths reported (277 breast cancer-specific). Higher OPG concentrations were associated with a higher risk of all-cause mortality (hazard ratio for 1-unit log2-transformed concentration (HR_log2) = 1.24 (95% confidence interval 1.03-1.49). Associations were observed in women diagnosed with ER-PR- tumors or discordant hormone receptor status (ER-PR-, HR_log2 = 1.93 (1.20-3.10); discordant ERPR, 1.70 (1.03-2.81)), but not for women with ER + PR + tumors (HR_log2 = 1.06 (0.83-1.35)). OPG was associated with a higher risk of recurrence among women with ER-PR- disease (HR_log2 = 2.18 (1.39-3.40)). We observed no associations between OPG and breast cancer-specific survival, or for TRAIL and any outcome.

CONCLUSIONS

Higher circulating OPG may be a biomarker of a higher risk of poor outcome among women diagnosed with ER- breast cancer. Further mechanistic studies are warranted.

Santin (5,7-Dihydroxy-3,6,4'-Trimetoxy-Flavone) Enhances TRAIL-Mediated Apoptosis in Colon Cancer Cells

TRAIL (Tumor necrosis factor-Related Apoptosis-Inducing Ligand) has the ability to selectively kill cancer cells without being toxic to normal cells. This endogenous ligand plays an important role in surveillance and anti-tumor immunity. However, numerous tumor cells are resistant to TRAIL-induced apoptosis. In this study, the apoptotic effect of santin in combination with TRAIL on colon cancer cells was examined. Flow cytometry was used to detect the apoptosis and expression of death receptors (TRAIL-R1/DR4 and TRAIL-R2/DR5). Mitochondrial membrane potential (ΔΨm) was evaluated by DePsipher staining with the use of fluorescence microscopy. We have shown for the first time that flavonoid santin synergizes with TRAIL to induce apoptosis in colon cancer cells. Santin induced TRAIL-mediated apoptosis through increased expression of death receptors TRAIL-R1 and TRAIL-R2 and augmented disruption of the mitochondrial membrane in SW480 and SW620 cancer cells. The obtained data may indicate the potential role of santin in colon cancer chemoprevention through the enhancement of TRAIL-mediated apoptosis.

Harnessing TRAIL-induced cell death for cancer therapy: a long walk with thrilling discoveries

Tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) can induce apoptosis in a wide variety of cancer cells, both in vitro and in vivo, importantly without killing any essential normal cells. These findings formed the basis for the development of TRAIL-receptor agonists (TRAs) for cancer therapy. However, clinical trials conducted with different types of TRAs have, thus far, afforded only limited therapeutic benefit, as either the respectively chosen agonist showed insufficient anticancer activity or signs of toxicity, or the right TRAIL-comprising combination therapy was not employed. Therefore, in this review we will discuss molecular determinants of TRAIL resistance, the most promising TRAIL-sensitizing agents discovered to date and, importantly, whether any of these could also prove therapeutically efficacious upon cancer relapse following conventional first-line therapies. We will also discuss the more recent progress made with regards to the clinical development of highly active non-immunogenic next generation TRAs. Based thereupon, we next propose how TRAIL resistance might be successfully overcome, leading to the possible future development of highly potent, cancer-selective combination therapies that are based on our current understanding of biology TRAIL-induced cell death. It is possible that such therapies may offer the opportunity to tackle one of the major current obstacles to effective cancer therapy, namely overcoming chemo- and/or targeted-therapy resistance. Even if this were achievable only for certain types of therapy resistance and only for particular types of cancer, this would be a significant and meaningful achievement.

RNA-seq and Single-Cell Transcriptome Analyses of TRAIL Receptors Gene Expression in Human Osteosarcoma Cells and Tissues

Osteosarcoma (OS) is the most common primary cancer in the skeletal system, characterized by a high incidence of lung metastasis, local recurrence and death. Systemic treatment of this aggressive cancer has not improved significantly since the introduction of chemotherapy regimens, underscoring a critical need for new treatment strategies. TRAIL receptors have long been proposed to be therapeutic targets for cancer treatment, but their role in osteosarcoma remains unclear. In this study, we investigated the expression profile of four TRAIL receptors in human OS cells using total RNA-seq and single-cell RNA-seq (scRNA-seq). The results revealed that TNFRSF10B and TNFRSF10D but not TNFRSF10A and TNFRSF10C are differentially expressed in human OS cells as compared to normal cells. At the single cell level by scRNA-seq analyses, TNFRSF10B, TNFRSF10D, TNFRSF10A and TNFRSF10C are most abundantly expressed in endothelial cells of OS tissues among nine distinct cell clusters. Notably, in osteoblastic OS cells, TNFRSF10B is most abundantly expressed, followed by TNFRSF10D, TNFRSF10A and TNFRSF10C. Similarly, in an OS cell line U2-OS using RNA-seq, TNFRSF10B is most abundantly expressed, followed by TNFRSF10D, TNFRSF10A and TNFRSF10C. According to the TARGET online database, poor patient outcomes were associated with low expression of TNFRSF10C. These results could provide a new perspective to design novel therapeutic targets of TRAIL receptors for the diagnosis, prognosis and treatment of OS and other cancers.

Functionalized calcium phosphate nanoparticles to direct osteoprotegerin to bone lesion sites in a medaka (Oryzias latipes) osteoporosis model

Calcium phosphate (CaP) is the inorganic part of hard tissues, such as bone, teeth and tendons, and has a high biocompatibility and good biodegradability. Therefore, CaP nanoparticles functionalized with DNA encoding bone anabolic factors are promising carrier-systems for future therapeutic development. Here, we analysed CaP nanoparticles in a genetically modified medaka fish model, where osteoporosis-like lesions can be induced by transgenic expression of receptor activator of nuclear factor kappa-B ligand (Rankl). Rankl-transgenic medaka were used to visualize and understand effects of microinjected functionalized CaP nanoparticles during modulation of osteoclast activity in vivo. For this, we synthetized multi-shell CaP nanoparticles by rapid precipitation of calcium lactate and ammonium hydrogen phosphate followed by the addition of plasmid DNA encoding the osteoclastogenesis inhibitory factor osteoprotegerin-b (Opgb). An additional layer of poly(ethyleneimine) was added to enhance cellular uptake. Integrity of the synthesized nanoparticles was confirmed by dynamic light scattering, scanning electron microscopy and energy dispersive X-ray spectroscopy. Fluorescently labelled CaP nanoparticles were microinjected into the heart, trunk muscle or caudal fins of Rankl-transgenic medaka embryos that expressed fluorescent reporters in various bone cell types. Confocal time-lapse imaging revealed a uniform distribution of CaP nanoparticles in injected tissues and showed that nanoparticles were efficiently taken up by macrophages that subsequently differentiated into bone-resorbing osteoclasts. After Rankl induction, fish injected with Opg-functionalized nanoparticles showed delayed or absent degradation of mineralized matrix, i.e. a lower incidence of osteoporosis-like phenotypes. This is proof of principle that CaP nanoparticles can be used as carriers to efficiently deliver modulatory compounds to osteoclasts and block their activity.

The Use of Hydroxyapatite Loaded with Doxycycline (HADOX) in Dentoalveolar Surgery as a Risk-Reduction Therapeutic Protocol in Subjects Treated with Different Bisphosphonate Dosages

Medication-related osteonecrosis of the jaw (MRONJ) is considered as a severe adverse side effect of specific drugs such as anti-resorptive and anti-angiogenic medications. Evidence suggests that MRONJ is linked to invasive dental procedures, mainly dentoalveolar surgery. Several preventive strategies to minimize the risk of developing MRONJ have been investigated. However, no investigation has been attempted to evaluate the therapeutic effect of local drug-delivery technology as a preventive strategy protocol. The aim of this study is to evaluate the efficacy of hydroxyapatite-containing doxycycline (HADOX) in rats with high-risk MRONJ development. All the rats used in this study were divided into seven groups. Six groups of rats out of seven were exposed to two different doses of antiresorptive drug therapy for four weeks before undergoing an upper incisor extraction. After 28 days, all the animals were euthanized, and the bone blocks were processed for histological and histomorphometrical evaluation. The histomorphometric analysis confirmed that newly formed bone (NFB) was present in all groups, with significant differences. NFB in the HADOX group treated with zoledronic acid at 4% showed (28.38; C.I. 22.29-34.48), which represents a significant increase compared to HA (15.69; C.I. 4.89-26.48) (p = 0.02). A similar pattern was observed in the HADOX group treated with zoledronic acid 8% ZA treatment (p = 0.001). Conclusions: HADOX did not inhibit any bone repair and reduced early inflammatory response. Hence, HADOX could promote bone healing in patients undergoing antiresorptive drug therapy.

Tetrandrine inhibits RANKL-induced osteoclastogenesis by promoting the degradation of TRAIL

Background

Tetrandrine, a bisbenzylisoquinoline (BBI) alkaloid extracted from Stephania tetrandra (S. Moore), and is widely used in several diseases such as tuberculosis, hyperglycemia, malaria, and tumors. Tetrandrine was recently shown to prevent bone loss in ovariectomized mice. However, the specific mechanism underlying osteoclastogenesis inhibition remains unclear.

Methods

Tetrandrine’s cytotoxicity to cells was determined using the Cell Counting Kit-8 assay. Tartrate-resistant acid phosphatase staining, immunofluorescence and bone resorption assay were performed to evaluate osteoclasts’ differentiation and absorption capacity. The bone-forming capacity was assessed using alkaline phosphatase and Alizarin red S staining. qPCR and Western blotting were applied to assess the related genes and protein expression. Tetrandrine’s impact on TRAIL was demonstrated through a co-immunoprecipitation assay. Animal experiments were performed for the detection of the therapeutic effect of Tetrandrine on osteoporosis.

Results

Tetrandrine attenuated RANKL-induced osteoclastogenesis and decreased the related gene expression. The co-immunoprecipitation assay revealed that Tetrandrine administration accelerated the ubiquitination of TNF-related apoptosis-inducing ligand (TRAIL), which was subsequently degraded. Moreover, TRAIL overexpression was found to partially reverse the Tetrandrine-induced inhibition of osteoclastogenesis. Meanwhile, Tetrandrine significantly inhibited the phosphorylation of p38, p65, JNK, IKBα and IKKα/β, while the TRAIL overexpression weakened this effect. In addition, Tetrandrine promoted osteogenesis and inhibited the TRAIL expression in osteoblasts. Tetrandrine consistently improved bone destruction by stimulating bone formation and inhibiting bone resorption in an OVX-induced mouse model.

Conclusion

Tetrandrine inhibits RANKL-induced osteoclastogenesis by promoting TRAIL degradation and promotes osteoblast differentiation, suggesting its potential in antiosteopenia pharmacotherapy.

Targeting TRAIL Death Receptors in Triple-Negative Breast Cancers: Challenges and Strategies for Cancer Therapy

The tumor necrosis factor (TNF) superfamily member TNF-related apoptosis-inducing ligand (TRAIL) induces apoptosis in cancer cells via death receptor (DR) activation with little toxicity to normal cells or tissues. The selectivity for activating apoptosis in cancer cells confers an ideal therapeutic characteristic to TRAIL, which has led to the development and clinical testing of many DR agonists. However, TRAIL/DR targeting therapies have been widely ineffective in clinical trials of various malignancies for reasons that remain poorly understood. Triple negative breast cancer (TNBC) has the worst prognosis among breast cancers. Targeting the TRAIL DR pathway has shown notable efficacy in a subset of TNBC in preclinical models but again has not shown appreciable activity in clinical trials. In this review, we will discuss the signaling components and mechanisms governing TRAIL pathway activation and clinical trial findings discussed with a focus on TNBC. Challenges and potential solutions for using DR agonists in the clinic are also discussed, including consideration of the pharmacokinetic and pharmacodynamic properties of DR agonists, patient selection by predictive biomarkers, and potential combination therapies. Moreover, recent findings on the impact of TRAIL treatment on the immune response, as well as novel strategies to address those challenges, are discussed.

Escaping cell death via TRAIL decoy receptors: a systematic review of their roles and expressions in colorectal cancer

The development of targeted therapy such as tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-based therapy has gained increasing attention as a promising new approach in cancer therapy. TRAIL specifically targets cancer cells while sparing the normal cells, thus, limiting the known side effects of the majority anti-cancer therapies. As more extensive research and clinical trials are conducted, resistance to TRAIL molecule has become one of the significant issues associated with the failure of TRAIL in treating colorectal cancer (CRC). To date, the exact mechanism by which TRAIL resistance may have occurred remains unknown. Interestingly, recent studies have revealed the critical role of the TRAIL decoy receptor family; consisting of decoy receptor 1 (DcR1; also known as TRAIL-R3), decoy receptor 2 (DcR2; also known as TRAIL-R4), and osteoprotegerin (OPG) in driving TRAIL resistance. This review highlights the expression of the decoy receptors in CRC and its possible association with the reduction in sensitivity towards TRAIL treatment based on the currently available in vitro, in vivo, and human studies. Additionally, discrepancies between the outcomes from different research groups are discussed, and essential areas are highlighted for future investigation of the roles of decoy receptors in modulating TRAIL-induced apoptosis. Overcoming TRAIL resistance through modulating the expression(s) and elucidating the role(s) of TRAIL decoy receptors hold great promise for TRAIL-based therapies to be extensively explored in treating human cancers including CRC.

AI-Based Protein Interaction Screening and Identification (AISID)

In this study, we presented an AISID method extending AlphaFold-Multimer's success in structure prediction towards identifying specific protein interactions with an optimized AISIDscore. The method was tested to identify the binding proteins in 18 human TNFSF (Tumor Necrosis Factor superfamily) members for each of 27 human TNFRSF (TNF receptor superfamily) members. For each TNFRSF member, we ranked the AISIDscore among the 18 TNFSF members. The correct pairing resulted in the highest AISIDscore for 13 out of 24 TNFRSF members which have known interactions with TNFSF members. Out of the 33 correct pairing between TNFSF and TNFRSF members, 28 pairs could be found in the top five (including 25 pairs in the top three) seats in the AISIDscore ranking. Surprisingly, the specific interactions between TNFSF10 (TNF-related apoptosis-inducing ligand, TRAIL) and its decoy receptors DcR1 and DcR2 gave the highest AISIDscore in the list, while the structures of DcR1 and DcR2 are unknown. The data strongly suggests that AlphaFold-Multimer might be a useful computational screening tool to find novel specific protein bindings. This AISID method may have broad applications in protein biochemistry, extending the application of AlphaFold far beyond structure predictions.

Biochemical characterization of a disease-causing human osteoprotegerin variant

Recently, a human mutation of OPG was identified to be associated with familial forms of osteoarthritis. This missense mutation (c.1205A =  > T; p.Stop402Leu) occurs on the stop codon of OPG, which results in a 19-residue appendage to the C-terminus (OPG+19). The biochemical consequence of this unusual sequence alteration remains unknown. Here we expressed OPG+19 in 293 cells and the mutant OPG was purified to homogeneity by heparin affinity chromatography and size exclusion chromatography. We found that in sharp contrast to wildtype OPG, which mainly exists in dimeric form, OPG+19 had a strong tendency to form higher-order oligomers. To our surprise, the hyper-oligomerization of OPG+19 had no impact on how it binds cell surface heparan sulfate, how it inhibits RANKL-induced osteoclastogenesis and TRAIL-induced chondrocytes apoptosis. Our data suggest that in biological contexts where OPG is known to play a role, OPG+19 functions equivalently as wildtype OPG. The disease-causing mechanism of OPG+19 likely involves an unknown function of OPG in cartilage homeostasis and mineralization. By demonstrating the biochemical nature of this disease-causing OPG mutant, our study will likely help elucidating the biological roles of OPG in cartilage biology.

Engagement of TRAIL triggers degranulation and IFNγ production in human natural killer cells

NK cells utilize a large array of receptors to screen their surroundings for aberrant or virus‐infected cells. Given the vast diversity of receptors expressed on NK cells we seek to identify receptors involved in the recognition of HIV‐1‐infected cells. By combining an unbiased large‐scale screening approach with a functional assay, we identify TRAIL to be associated with NK cell degranulation against HIV‐1‐infected target cells. Further investigating the underlying mechanisms, we demonstrate that TRAIL is able to elicit multiple effector functions in human NK cells independent of receptor‐mediated induction of apoptosis. Direct engagement of TRAIL not only results in degranulation but also IFNγ production. Moreover, TRAIL‐mediated NK cell activation is not limited to its cognate death receptors but also decoy receptor I, adding a new perspective to the perceived regulatory role of decoy receptors in TRAIL‐mediated cytotoxicity. Based on these findings, we propose that TRAIL not only contributes to the anti‐HIV‐1 activity of NK cells but also possesses a multifunctional role beyond receptor‐mediated induction of apoptosis, acting as a regulator for the induction of different effector functions.

Inhibition of matrix metalloproteinase expression by selective clearing of senescent dermal fibroblasts attenuates ultraviolet-induced photoaging

Photoaging mainly occurs due to ultraviolet (UV) radiation, and is accompanied by increased secretion of matrix metalloproteinases (MMPs) and degradation of collagen. UV radiation induces cell senescence in the skin; however, the role of senescent cells in photoaging remains unclear. Therefore, to elucidate the role of senescent cells in photoaging, we evaluated the effect of senolytics in a photoaging mouse model and investigated the underlying mechanism of their antiaging effect. Both UV-induced senescent human dermal fibroblasts and a photoaging mouse model, ABT-263 and ABT-737, demonstrated senolytic effects on senescent fibroblasts. Moreover, we found that several senescence-associated secretory phenotype factors, such as IL-6, CCL5, CCL7, CXCL12, and SCF, induced MMP-1 expression in dermal fibroblasts, which decreased after treatment with ABT-263 and ABT-737 in vivo and in vitro. Both senolytic drugs attenuated the induction of MMPs and decreased collagen density in the photoaging mouse model. Our data suggest that senolytic agents reduce UV-induced photoaging, making strategies for targeting senescent dermal fibroblasts promising options for the treatment of photoaging.

A Journey into Animal Models of Human Osteomyelitis: A Review

Osteomyelitis is an infection of the bone characterized by progressive inflammatory destruction and apposition of new bone that can spread via the hematogenous route (hematogenous osteomyelitis (HO)), contiguous spread (contiguous osteomyelitis (CO)), and direct inoculation (osteomyelitis associated with peripheral vascular insufficiency (PVI)). Given the significant financial burden posed by osteomyelitis patient management, the development of new preventive and treatment methods is warranted. To achieve this objective, implementing animal models (AMs) of infection such as rats, mice, rabbits, avians, dogs, sheep, goats, and pigs might be of the essence. This review provides a literature analysis of the AMs developed and used to study osteomyelitis. Historical relevance and clinical applicability were taken into account to choose the best AMs, and some study methods are briefly described. Furthermore, the most significant strengths and limitations of each species as AM are discussed, as no single model incorporates all features of osteomyelitis. HO's clinical manifestation results in extreme variability between patients due to multiple variables (e.g., age, sex, route of infection, anatomical location, and concomitant diseases) that could alter clinical studies. However, these variables can be controlled and tested through different animal models.

The roles of osteoprotegerin in cancer, far beyond a bone player

Osteoprotegerin (OPG), also known as tumor necrosis factor receptor superfamily member 11B (TNFRSF11B), is a member of the tumor necrosis factor (TNF) receptor superfamily. Characterized by its ability to bind to receptor activator of nuclear factor kappa B ligand (RANKL), OPG is critically involved in bone remodeling. Emerging evidence implies that OPG is far beyond a bone-specific modulator, and is involved in multiple physiological and pathological processes, such as immunoregulation, vascular function, and fibrosis. Notably, numerous preclinical and clinical studies have been conducted to assess the participation of OPG in tumorigenesis and cancer development. Mechanistic studies have demonstrated that OPG is involved in multiple hallmarks of cancer, including tumor survival, epithelial to mesenchymal transition (EMT), neo-angiogenesis, invasion, and metastasis. In this review, we systematically summarize the basis and advances of OPG from its molecular structure to translational applications. In addition to its role in bone homeostasis, the physiological and pathological impacts of OPG on human health and its function in cancer progression are reviewed, providing a comprehensive understanding of OPG. We aim to draw more attention to OPG in the field of cancer, and to propose it as a promising diagnostic or prognostic biomarker as well as potential therapeutic target for cancer.

A new nomogram model for prognosis of hepatocellular carcinoma based on novel gene signature that regulates cross-talk between immune and tumor cells

Background

The combined application of immune cells and specific biomarkers related to the tumor immune microenvironment has a better predictive value for the prognosis of HCC. The purpose of this study is to construct a new prognostic model based on immune-related genes that regulate cross-talk between immune and tumor cells to assess the prognosis and explore possible mechanisms.

Method

The immune cell abundance ratio of 424 cases in the TCGA-LIHC database is obtained through the CIBERSORT algorithm. The differential gene analysis and cox regression analysis is used to screen IRGs. In addition, the function of IRGs was preliminarily explored through the co-culture of M2 macrophages and HCC cell lines. The clinical validation, nomogram establishment and performing tumor microenvironment score were validated.

Results

We identified 4 immune cells and 9 hub genes related to the prognosis. Further, we identified S100A9, CD79B, TNFRSF11B as an IRGs signature, which is verified in the ICGC and GSE76427 database. Importantly, IRGs signature is closely related to the prognosis, tumor microenvironment score, clinical characteristics and immunotherapy, and nomogram combined with clinical characteristics is more conducive to clinical promotion. In addition, after co-culture with M2 macrophages, the migration capacity and cell pseudopod of MHCC97H increased significantly. And CD79B and TNFRSF11B were significantly down-regulated in MHCC97H, Huh7 and LM3, while S100A9 was up-regulated.

Conclusion

We constructed an IRGs signature and discussed possible mechanisms. The nomogram established based on IRGs can accurately predict the prognosis of HCC patients. These findings may provide a suitable therapeutic target for HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09465-9.

Osteoprotegerin Is a Better Predictor for Cardiovascular and All-Cause Mortality than Vascular Calcifications in a Multicenter Cohort of Patients on Peritoneal Dialysis

The purpose of this study was to compare vascular calcification (VC), serum osteoprotegerin (OPG) levels, and other biochemical markers to determine their value as available predictors of all-cause and cardiovascular (CV) mortality in patients on peritoneal dialysis (PD). A total of 197 patients were recruited from seven dialysis centers in Mexico City. VC was assessed with multi-slice computed tomography, measured using the calcification score (CaSc). OPG, albumin, calcium, hsC-reactive protein, phosphorous, osteocalcin, total alkaline phosphatase, and intact parathormone were also analyzed. Follow-up and mortality analyses were assessed using the Cox regression model. The mean age was 43.9 ± 12.9 years, 64% were males, and 53% were diabetics. The median OPG was 11.28 (IQR: 7.6−17.4 pmol/L), and 42% of cases had cardiovascular calcifications. The median VC was 424 (IQR:101−886). During follow-up (23 ± 7 months), there were 34 deaths, and 44% were cardiovascular in origin. In multivariable analysis, OPG was a significant predictor for all-cause (HR 1.08; p < 0.002) and CV mortality (HR 1.09; p < 0.013), and performed better than VC (HR 1.00; p < 0.62 for all-cause mortality and HR 1.00; p < 0.16 for CV mortality). For each mg/dL of albumin-corrected calcium, there was an increased risk for CV mortality, and each g/dL of albumin decreased the risk factor for all-cause mortality. OPG levels above 14.37 and 13.57 pmol/L showed the highest predictive value for all-cause and CV mortality in incident PD patients and performed better than VC.

The concept of intrinsic versus extrinsic apoptosis

Regulated cell death is a vital and dynamic process in multicellular organisms that maintains tissue homeostasis and eliminates potentially dangerous cells. Apoptosis, one of the better-known forms of regulated cell death, is activated when cell-surface death receptors like Fas are engaged by their ligands (the extrinsic pathway) or when BCL-2-family pro-apoptotic proteins cause the permeabilization of the mitochondrial outer membrane (the intrinsic pathway). Both the intrinsic and extrinsic pathways of apoptosis lead to the activation of a family of proteases, the caspases, which are responsible for the final cell demise in the so-called execution phase of apoptosis. In this review, I will first discuss the most common types of regulated cell death on a morphological basis. I will then consider in detail the molecular pathways of intrinsic and extrinsic apoptosis, discussing how they are activated in response to specific stimuli and are sometimes overlapping. In-depth knowledge of the cellular mechanisms of apoptosis is becoming more and more important not only in the field of cellular and molecular biology but also for its translational potential in several pathologies, including neurodegeneration and cancer.

Identification of the Key Immune-Related Genes in Chronic Obstructive Pulmonary Disease Based on Immune Infiltration Analysis

Purpose

Chronic obstructive pulmonary disease (COPD) is a major cause of death and morbidity worldwide. A better understanding of new biomarkers for COPD patients and their complex mechanisms in the progression of COPD are needed.

Methods

An algorithm was conducted to reveal the proportions of 22 subsets of immune cells in COPD samples. Differentially expressed immune-related genes (DE-IRGs) were obtained based on the differentially expressed genes (DEGs) of the GSE57148 dataset, and 1509 immune-related genes (IRGs) were downloaded from the ImmPort database. Functional enrichment analyses of DE-IRGs were conducted by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses and Ingenuity Pathway Analysis (IPA). We defined the DE-IRGs that had correlations with immune cells as hub genes. The potential interactions among the hub genes were explored by a protein-protein interaction (PPI) network.

Results

The CIBERSORT results showed that lung tissue of COPD patients contained a greater number of resting NK cells, activated dendritic cells, and neutrophils than normal samples. However, the fractions of follicular helper T cells and resting dendritic cells were relatively lower. Thirty-eight DE-IRGs were obtained for further analysis. Functional enrichment analysis revealed that these DE-IRGs were significantly enriched in several immune-related biological processes and pathways. Notably, we also observed that DE-IRGs were associated with the coronavirus disease COVID-19 in the progression of COPD. After correlation analysis, six DE-IRGs associated with immune cells were considered hub genes, including AHNAK, SLIT2 TNFRRSF10C, CXCR1, CXCR2, and FCGR3B.

Conclusion

In the present study, we investigated immune-related genes as novel diagnostic biomarkers and explored the potential mechanism for COPD based on CIBERSORT analysis, providing a new understanding for COPD treatment.