Mycobacterium tuberculosis Induced Osteoblast Dysregulation Involved in Bone Destruction in Spinal Tuberculosis

A review of bacterial and osteoclast differentiation in bone infection

Bone infections are characterized by bacterial invasion of the bone microenvironment and subsequent bone structure deterioration. This holds significance because osteoclasts, which are the only cells responsible for bone resorption, are abnormally stimulated during bone infections. Multiple communication factors secreted by bone stromal cells regulate the membrane of osteoclast progenitor cells, thereby maintaining bone homeostasis through the expression of many types of receptors. During infection, the immunoinflammatory response triggered by bacterial invasion and multiple virulence factors of bacterial origin can disrupt osteoclast homeostasis. Therefore, clarifying the pathways through which bacteria affect osteoclasts can offer a theoretical basis for preventing and treating bone infections. This review summarizes studies investigating bone destruction caused by different bacterial infections. In conclusion, bacteria can affect osteoclast metabolic activity through multiple pathways, including direct contact, release of virulence factors, induction of immunoinflammatory responses, influence on bone stromal cell metabolism, and intracellular infections.

Unmasking Pott Disease: A Diagnostic Challenge Mimicking Metastatic Lung Cancer - A Case Report

BACKGROUND Tuberculosis spondylitis, also known as Pott disease, is a rare form of the ancient infectious disease tuberculosis. It bears a complex clinical and radiological profile, often necessitating an extensive differential diagnostic approach for accurate identification. The disease was named in honor of the first diagnosed patient, highlighting its historical significance. CASE REPORT We report a case involving a 69-year-old male initially admitted to the Pulmonology Department under the suspicion of a left lung tumor, as indicated by a chest X-ray. A subsequent CT scan revealed a tumor-hilar mass, enlarged subcarineal lymph nodes, and a pathological mass at the C6/C7 vertebral level. Despite negative tuberculosis tests, the patient was misdiagnosed with disseminated lung cancer with spinal metastases. Following radiotherapy targeting the cervical and thoracic spine, the definitive diagnosis of spinal tuberculosis was confirmed via histopathological examination from an open biopsy of the C6 and C7 vertebrae. CONCLUSIONS Tuberculosis can present with an insidious and misleading clinical picture, often mimicking other diseases such as cancer. Early and accurate diagnostic processes are crucial for effective treatment. This case underscores the importance of considering tuberculosis in the differential diagnosis, especially when clinical presentations are ambiguous.

Plasma metabolomic analysis reveals the metabolic characteristics and potential diagnostic biomarkers of spinal tuberculosis

Objectives

This study aimed to conduct a non-targeted metabolomic analysis of plasma from patients with spinal tuberculosis (STB) to systematically elucidate the metabolomic alterations associated with STB, and explore potential diagnostic biomarkers for STB.

Methods

From January 2020 to January 2022, 30 patients with spinal tuberculosis (STBs) clinically diagnosed at the General Hospital of Ningxia Medical University and 30 age- and sex-matched healthy controls (HCs) were selected for this study. Using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) based metabolomics, we analyzed the metabolic profiles of 60 plasma samples. Statistical analyses, pathway enrichment, and receiver operating characteristic (ROC) analyses were performed to screen and evaluate potential diagnostic biomarkers.

Results

Metabolomic profiling revealed distinct alterations between the STBs and HCs cohorts. A total of 1635 differential metabolites were screened, functionally clustered, and annotated. The results showed that the differential metabolites were enriched in sphingolipid metabolism, tuberculosis, cutin, suberine and wax biosynthesis, beta-alanine metabolism, methane metabolism, and other pathways. Through the random forest algorithm, LysoPE (18:1(11Z)/0:0), 8-Demethyl-8-formylriboflavin 5'-phosphate, Glutaminyl-Gamma-glutamate, (2R)-O-Phospho-3-sulfolactate, and LysoPE (P-16:0/0:0) were determined to have high independent diagnostic value.

Conclusions

STBs exhibited significantly altered metabolite profiles compared with HCs. Here, we provide a global metabolomic profile and identify potential diagnostic biomarkers of STB. Five potential independent diagnostic biomarkers with high diagnostic value were screened. This study provides novel insights into the pathogenesis, diagnosis, and treatment strategies of STB.

Differentiation of Native Vertebral Osteomyelitis: A Comprehensive Review of Imaging Techniques and Future Applications

Native vertebral osteomyelitis, also termed spondylodiscitis, is an antibiotic-resistant disease that requires long-term treatment. Without proper treatment, NVO can lead to severe nerve damage or even death. Therefore, it is important to accurately diagnose the cause of NVO, especially in spontaneous cases. Infectious NVO is characterized by the involvement of 2 adjacent vertebrae and intervertebral discs, and common infectious agents include Staphylococcus aureus, Mycobacterium tuberculosis, Brucella abortus, and fungi. Clinical symptoms are generally nonspecific, and early diagnosis and appropriate treatment can prevent irreversible sequelae. Advances in pathologic histologic imaging have led physicians to look more forward to being able to differentiate between tuberculous and septic spinal discitis. Therefore, research in identifying and differentiating the imaging features of these 4 common NVOs is essential. Due to the diagnostic difficulties, clinical and radiologic diagnosis is the mainstay of provisional diagnosis. With the advent of the big data era and the emergence of convolutional neural network algorithms for deep learning, the application of artificial intelligence (AI) technology in orthopedic imaging diagnosis has gradually increased. AI can assist physicians in imaging review, effectively reduce the workload of physicians, and improve diagnostic accuracy. Therefore, it is necessary to present the latest clinical research on NVO and the outlook for future AI applications.

Giant Cells of Various Lesions Are Characterised by Different Expression Patterns of HLA-Molecules and Molecules Involved in the Cell Cycle, Bone Metabolism, and Lineage Affiliation: An Immunohistochemical Study with a Review of the Literature

Giant cells (GCs) are thought to originate from the fusion of monocytic lineage cells and arise amid multiple backgrounds. To compare GCs of different origins, we immunohistochemically characterised the GCs of reactive and neoplastic lesions (n = 47). We studied the expression of 15 molecules including HLA class II molecules those relevant to the cell cycle, bone metabolism and lineage affiliation. HLA-DR was detectable in the GCs of sarcoidosis, sarcoid-like lesions, tuberculosis, and foreign body granuloma. Cyclin D1 was expressed by the GCs of neoplastic lesions as well as the GCs of bony callus, fibroid epulis, and brown tumours. While cyclin E was detected in the GCs of all lesions, p16 and p21 showed a heterogeneous expression pattern. RANK was expressed by the GCs of all lesions except sarcoid-like lesions and xanthogranuloma. All GCs were RANK-L-negative, and the GCs of all lesions were osteoprotegerin-positive. Osteonectin was limited to the GCs of chondroblastoma. Osteopontin and TRAP were detected in the GCs of all lesions except xanthogranuloma. RUNX2 was heterogeneously expressed in the reactive and neoplastic cohort. The GCs of all lesions except foreign body granuloma expressed CD68, and all GCs were CD163- and langerin-negative. This profiling points to a functional diversity of GCs despite their similar morphology.

B. abortus Infection Promotes an Imbalance in the Adipocyte-Osteoblast Crosstalk Favoring Bone Resorption

Osteoarticular injury is the most common presentation of active brucellosis in humans. Osteoblasts and adipocytes originate from mesenchymal stem cells (MSC). Since those osteoblasts are bone-forming cells, the predilection of MSC to differentiate into adipocytes or osteoblasts is a potential factor involved in bone loss. In addition, osteoblasts and adipocytes can be converted into each other according to the surrounding microenvironment. Here, we study the incumbency of B. abortus infection in the crosstalk between adipocytes and osteoblasts during differentiation from its precursors. Our results indicate that soluble mediators present in culture supernatants from B. abotus-infected adipocytes inhibit osteoblast mineral matrix deposition in a mechanism dependent on the presence of IL-6 with the concomitant reduction of Runt-related transcription factor 2 (RUNX-2) transcription, but without altering organic matrix deposition and inducing nuclear receptor activator ligand kβ (RANKL) expression. Secondly, B. abortus-infected osteoblasts stimulate adipocyte differentiation with the induction of peroxisome proliferator-activated receptor γ (PPAR-γ) and CCAAT enhancer binding protein β (C/EBP-β). We conclude that adipocyte-osteoblast crosstalk during B. abortus infection could modulate mutual differentiation from its precursor cells, contributing to bone resorption.