Updates on Paget's Disease of Bone

The role of γδ T cells in flavivirus infections: Insights into immune defense and therapeutic opportunities

γδ T cells are a unique subset of unconventional T cells and an important component of the innate immune system. Unlike conventional αβ T cells, γδ T cells can respond rapidly during the early stages of infection, and their antigen recognition is not restricted by MHC molecules. These distinctive features underscore the important role of γδ T cells in viral clearance and infection control. Therefore, γδ T cell-based immunotherapies have been extensively explored for the treatment of a variety of diseases, including viral infections and cancers. Several therapeutic strategies based on γδ T cells have advanced to clinical trials, demonstrating promising safety and efficacy. Currently, there are no effective treatments for flavivirus infections, which are typically characterized by acute onset. Research has shown that γδ T cells can rapidly expand during the early phases of flavivirus infections and effectively suppress viral replication, making them an attractive target for the development of novel therapies for flavivirus infections. This review aims to highlight the immunological roles of γδ T cells in flavivirus infections and to explore the potential of γδ T cell-based therapeutic strategies for the prevention and treatment of these infections.

Signaling Dynamics in Osteogenesis: Unraveling Therapeutic Targets for Bone Generation

Diseases affecting bone encompass a spectrum of disorders, from prevalent conditions such as osteoporosis and Paget's disease, collectively impacting millions, to rare genetic disorders including Fibrodysplasia Ossificans Progressiva (FOP). While several classes of drugs, such as bisphosphonates, synthetic hormones, and antibodies, are utilized in the treatment of bone diseases, their efficacy is often curtailed by issues of tolerability and high incidence of adverse effects. Developing therapeutic agents for bone diseases is hampered by the fact that numerous pathways regulating bone metabolism also perform pivotal functions in other organ systems. Consequently, the selection of an appropriate target is a complicated process despite the significant demand for novel medications to address bone diseases. Research has shown the role of various cell signaling pathways, including Wnt, PTHR1, CASR, BMPRs, OSCAR, and TWIST1, in the regulation of osteogenesis, bone remodeling, and homeostasis. Disruptions in bone homeostasis can result in decreased bone density and the onset of osteoporosis. There remains a need for the development of drugs that can enhance bone remodeling with improved side effects profiles. The exploration of promising targets to stimulate bone formation has the potential to significantly advance the field of bone-related medical care, thereby improving the quality of life for millions. Additionally, a deeper understanding of anabolic and catabolic pathway mechanisms could enable future studies to explore synergistic effects between unrelated pathways. Herein, we explore potential drug targets that may be exploited therapeutically using small molecule agonists or antagonists to promote bone remodeling and discuss their advantages and limitations.

Osteogenesis imperfecta type 10 and the cellular scaffolds underlying common immunological diseases

Osteogenesis imperfecta type 10 (OI10) is caused by loss of function codon variants in the gene SERPINH1 that encodes heat shock protein 47 (HSP47), rather than in a gene specifying bone formation. The HSP47 variants disrupt the folding of both collagen and the endonuclease IRE1α (inositol-requiring enzyme 1α) that splices X-Box Binding Protein 1 (XBP1) mRNA. Besides impairing bone development, variants likely affect osteoclast differentiation. Three distinct biochemical scaffold play key roles in the differentiation and regulated cell death of osteoclasts. These scaffolds consist of non-templated protein modifications, ordered lipid arrays, and protein filaments. The scaffold components are specified genetically, but assemble in response to extracellular perturbagens, pathogens, and left-handed Z-RNA helices encoded genomically by flipons. The outcomes depend on interactions between RIPK1, RIPK3, TRIF, and ZBP1 through short interaction motifs called RHIMs. The causal HSP47 nonsynonymous substitutions occur in a novel variant leucine repeat region (vLRR) that are distantly related to RHIMs. Other vLRR protein variants are causal for a variety of different mendelian diseases. The same scaffolds that drive mendelian pathology are associated with many other complex disease outcomes. Their assembly is triggered dynamically by flipons and other context-specific switches rather than by causal, mendelian, codon variants.

Effects of Erythropoietin-Promoted Fracture Healing on Bone Turnover Markers in Cats

In orthopaedics, erythropoietin (EPO) is applied in the preoperative management of anaemic patients, but also as a stimulating factor to assist bone regeneration due to its angiogenic and osteoinductive potential. Since orthopaedists mainly rely on their clinical experience to assess bone healing, additional and more objective methods such as studying the dynamics of bone markers are needed. Therefore, the aim of this study was to investigate the plasma activity of bone-specific alkaline phosphatase (BALP), the N-terminal propeptide of type I collagen (PINP), the C-terminal telopeptide of type I collagen (CTX), and deoxypyridinoline (DPD) during the first 2 months of healing of comminuted fractures in cats, either non-stimulated or locally stimulated with recombinant human erythropoietin (rhEPO). The study included twelve cats of mixed breeds, aged 7.2 ± 4 months, weighing 2.11 ± 1.1 kg, with comminuted diaphyseal fractures of the femur. Surgical treatment with plate osteosynthesis was performed in all animals. The cats were randomly divided into two groups-a control (n = 6) and an EPO group (n = 6). The locally applied EPO leads to the increased activity of bone formation markers (BALP and PINP) during the second week after the osteosynthesis, preceding the peaks in the control group by two weeks. The studied bone resorption markers (DPD, CTX) varied insignificantly during the studied period. In conclusion, erythropoietin could serve as a promoter of bone healing in comminuted fractures in cats.

Paget's disease of bone in the patient presented with a bowed leg

Key Clinical Message

In dealing with bowed limbs along with increased alkaline phosphatase (ALP), even if the typical changes to the face are not very noticeable at first glance, Paget's disease of the bone (PDB) should be suspected, and the necessary investigations should be carried out to confirm the diagnosis.

Abstract

Paget's disease of the bone (PDB) is the second most prevalent metabolic bone disorder worldwide with disorganized bone remodeling. Here, a patient is presented with pain and bending of the right leg, whose skull and forehead changes are not noticeable at first glance, but with clinical suspicion and additional diagnostic evaluations, PDB diagnosis is confirmed for the patient.

Newly Diagnosed Monostotic Paget's Disease of Bone during Living Kidney Donor Candidate Evaluation

The popularity of living-donor organ donation has increased recently as an alternative to deceased-organ donation due to the growing need for organs and a shortage of deceased-donor organs. This procedure requires an in-depth health assessment of candidates, who must be in excellent physical and mental health. We present a potential living-kidney donor withdrawn from donation due to a newly diagnosed Paget's disease of bone (PDB). The patient underwent computed tomography (CT), magnetic resonance imaging (MRI), bone scintigraphy, and bone densitometry with trabecular bone score (TBS) assessment. The sole lumbar vertebra affected by PDB was investigated comprehensively, non-invasively, quantitatively, and qualitatively.