differentiation-functional-osteoclasts-from-human-peripheral-blood

Differentiation of Functional Osteoclasts from Human Peripheral Blood CD14<sup>+</sup> Monocytes

Osteoclasts (OCs) are bone-resorbing cells that play a pivotal role in skeletal development and adult bone remodeling. Several bone disorders are caused ...

University of Glasgow

We undertook this study to examine microRNA (miRNA) expression across rheumatoid arthritis (RA) phenotypes, along with the effects and mechanisms of action of miRNA-17-5p (miR-17).

MicroRNA-17-5p Reduces Inflammation and Bone Erosions in Mice With Collagen-Induced Arthritis and Directly Targets the JAK/STAT Pathway in Rheumatoid Arthritis Fibroblast-like Synoviocytes.

Fibrotic disorders represent common complex disease pathologies that are therapeutically challenging. Inflammation is associated with numerous fibrotic pathogeneses; however, its role in the multifaceted mechanisms of fibrosis remains unclear. IL-13 is implicated in aberrant responses involved in fibrotic disease, and we aimed to understand its role in the inflammatory processes of a common fibrotic disorder, Dupuytren's disease. We demonstrated T-cells produced IFN-g, which induced IL-13 secretion from mast cells and up-regulated IL-13Ra1 on fibroblasts, rendering them more reactive to IL-13. Consequently, diseased myofibroblasts demonstrated enhanced fibroproliferative effects upon IL-13 stimulation. We established IFN-g and IL-13 responses involved STAT dependent pathways, and STAT targeting (tofacitinib) could inhibit IL-13 production from mast cells, IL-13Ra1 up-regulation in fibroblasts and fibroproliferative effects of IL-13 on diseased myofibroblasts. Accordingly, utilizing Dupuytren's as an accessible human model of fibrosis, we propose targeting STAT pathways may offer previously unidentified therapeutic approaches in the management of fibrotic disease.

Attenuation of Dupuytren's fibrosis via targeting of the STAT1 modulated IL-13Rα1 response.

Increasing evidence suggests that inflammatory mechanisms play a key role in chronic tendon disease. After observing T cell signatures in human tendinopathy, we explored the interaction between T cells and tendon stromal cells or tenocytes to define their functional contribution to tissue remodelling and inflammation amplification and hence disease perpetuation.

Novel self-amplificatory loop between T cells and tenocytes as a driver of chronicity in tendon disease.

Circulating myeloid precursors are responsible for post-natal osteoclast (OC) differentiation and skeletal health, although the exact human precursors have not been defined. Enhanced osteoclastogenesis contributes to joint destruction in rheumatoid arthritis (RA) and tumour necrosis factor (TNF) is a well-known pro-osteoclastogenic factor. Herein, we investigated the interplay between receptor activator of nuclear factor kappa-Β ligand (RANK-L), indispensable for fusion of myeloid precursors and the normal development of OCs, and TNF in directing the differentiation of diverse pre-OC populations derived from human peripheral blood.

TNF is a homoeostatic regulator of distinct epigenetically primed human osteoclast precursors.

Psoriatic arthritis (PsA) is associated with bone erosion and inflammation-induced bone loss, which are mediated by osteoclasts (OC) and modulated by inflammatory cytokines. Apremilast (APR) (a selective phosphodiesterase 4 inhibitor) is efficacious in PsA and acts by inhibiting cytokine production. However, there are no direct data informing whether and how APR affects osteoclast formation in humans.

Apremilast inhibits inflammatory osteoclastogenesis.

Models of bone remodelling could be useful in drug discovery, particularly if the model is one that replicates bone regeneration with reduction in osteoclast activity. Here we use nanovibrational stimulation to achieve this in a 3D co-culture of primary human osteoprogenitor and osteoclast progenitor cells. We show that 1000 Hz frequency, 40 nm amplitude vibration reduces osteoclast formation and activity in human mononuclear CD14 blood cells. Additionally, this nanoscale vibration both enhances osteogenesis and reduces osteoclastogenesis in a co-culture of primary human bone marrow stromal cells and bone marrow hematopoietic cells. Further, we use metabolomics to identify Akt (protein kinase C) as a potential mediator. Akt is known to be involved in bone differentiation via transforming growth factor beta 1 (TGFβ1) and bone morphogenetic protein 2 (BMP2) and it has been implicated in reduced osteoclast activity via Guanine nucleotide-binding protein subunit α13 (Gα13). With further validation, our nanovibrational bioreactor could be used to help provide humanised 3D models for drug screening.

Nanovibrational stimulation inhibits osteoclastogenesis and enhances osteogenesis in co-cultures.

Bone disease represents a major cause of morbidity and mortality in Multiple Myeloma (MM); primarily driven by osteoclasts whose differentiation is dependent on expression of RANKL by MM cells. Notably, costimulation by ITAM containing receptors (i.e., FcγR) can also play a crucial role in osteoclast differentiation. Modeling the pathology of the bone marrow microenvironment with an  culture system of primary human multiple myeloma cells, we herein demonstrate that FcγR-mediated signaling, via staphylococcal protein A (SpA) IgG immune-complexes, can act as a critical negative regulator of MM-driven osteoclast differentiation. Interrogation of the mode-of-action revealed that FcγR-mediated signaling causes epigenetic modulation of chromosomal 3D architecture at the RANK promoter; with altered spatial orientation of a proximal super enhancer. Combined this leads to substantial down-regulation of RANK at a transcript, protein, and functional level. These observations shed light on a novel mechanism regulating RANK expression and provide a rationale for targeting FcγR-signaling for the amelioration of osteolytic bone pathology in disease.

Shatakshi Sood

School of Infection & Immunity

University of Glasgow

Differentiation of Functional Osteoclasts from Human Peripheral Blood CD14⁺ Monocytes

Shatakshi Sood

School of Infection & Immunity

University of Glasgow

Differentiation of Functional Osteoclasts from Human Peripheral Blood CD14+ Monocytes

Differentiation of Functional Osteoclasts from Human Peripheral Blood CD14⁺ Monocytes