Metabolic switching and cell wall remodelling of Mycobacterium tuberculosis during bone tuberculosis

Mycobacterium tuberculosis specific protein Rv1509 modulates osteoblast and osteoclast differentiation via TLR2 signaling

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), is one of the most ancient diseases recorded. In cases of bone TB, it significantly disrupts bone homeostasis, though the precise mechanisms are poorly understood and effective treatment targets are scarce. Our study investigated the role of Rv1509 in the pathogenesis of bone TB. We found that Rv1509 enhances the differentiation of bone marrow macrophages (BMMs) into osteoclasts by activating the TLR2 pathway, which stimulates the production of IL-6 and TNF-α. This, in turn, indirectly inhibits osteoblast differentiation and mineralization. Additionally, Rv1509 directly impairs osteoblast function and enhances the secretion of RANKL via TLR2 signaling, creating a detrimental RANKL/OPG imbalance that promotes osteoclast differentiation and bone degradation. Notably, the injection of Rv1509 into mouse skulls led to extensive bone damage, highlighting its significant role as a virulence factor in the pathogenesis of bone TB.

Functional Amino Acids in the Regulation of Bone and Its Diseases

Bone as a vigorous tissue is constantly undergoing bone remodeling. The homeostasis of bone remodeling requires combined efforts of multifarious bone cells. Amino acids (AA), known as essential components of life support, are closely related to the regulation of bone homeostasis. In recent years, the concept of functional amino acids (FAAs) has been proposed, which is defined as AA that regulate key metabolic pathways to improve health, survival, growth, development, lactation, and reproduction of organisms, to highlight their outstanding contributions in the body. In the hope of exploring new therapeutic strategies, this review focus on summarizing recent progress in the vital role of FAAs in bone homeostasis maintaining and potential implications of FAAs in bone-related diseases, and discussing related mechanisms. The results showed that FAAs are closely related to bone metabolism and therapeutic strategy targeting FAAs metabolism is one of the future trends for bone disorders, while the explorations about possible impact of FAAs-based diets are still limited.

Next-Gen Dual Transcriptomics for Adult Extrapulmonary Tuberculosis Biomarkers and Host-Pathogen Interplay in Human Cells: A Strategic Review

Tuberculosis (TB) is a major public health concern that results in significant morbidity and mortality, particularly in middle- to low-income countries. Extra-pulmonary tuberculosis (EPTB) in adults is a form of TB that affects organs other than the lungs and is challenging to diagnose and treat due to a lack of accurate early diagnostic markers and inadequate knowledge of host immunity. Next-generation sequencing-based approaches have shown potential for identifying diagnostic biomarkers and host immune responses related to EPTB. This strategic review discusses on the significance using primary human cells and cell lines for in vitro transcriptomic studies on common forms of EPTB, such as lymph node TB, brain TB, bone TB, and endometrial TB to derive potential insights. While organoids have shown promise as a model system, primary cell lines still remain a valuable tool for studying host-pathogen interplay due to their conserved immune system, non-iPSC origin, and lack of heterogeneity in cell population. This review outlines a basic workflow for researchers interested in performing transcriptomics studies in EPTB, and also discusses the potential of cell-line based dual RNA-Seq technology for deciphering comprehensive transcriptomic signatures, host-pathogen interplay, and biomarkers from the host and Mycobacterium tuberculosis. Thus, emphasizing the implementation of this technique which can significantly contribute to the global anti-TB effort and advance our understanding of EPTB.

Graphical Abstract