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Preventive CCL2/CCR2 Axis Blockade Suppresses Osteoclast Activity in a Mouse Model of Rheumatoid Arthritis by Reducing Homing of CCR2^hi Osteoclast Progenitors to the Affected Bone.

ABSTRACT: Detailed characterization of medullary and extramedullary reservoirs of osteoclast progenitors (OCPs) is required to understand the pathophysiology of increased periarticular and systemic bone resorption in arthritis. In this study, we focused on identifying the OCP population specifically induced by arthritis and the role of circulatory OCPs in inflammatory bone loss. In addition, we determined the relevant chemokine axis responsible for their migration, and targeted the attraction signal to reduce bone resorption in murine collagen-induced arthritis (CIA). OCPs were expanded in periarticular as well as circulatory compartment of arthritic mice, particularly the CCR2^hi subset. This subset demonstrated enhanced osteoclastogenic activity in arthritis, whereas its migratory potential was susceptible to CCR2 blockade in vitro. Intravascular compartment of the periarticular area contained increased frequency of OCPs with the ability to home to the arthritic bone, as demonstrated in vivo by intravascular staining and adoptive transfer of splenic LysMcre/Ai9 tdTomato-expressing cells. Simultaneously, CCL2 levels were increased locally and systemically in arthritic mice. Mouse cohorts were treated with the small-molecule inhibitor (SMI) of CCR2 alone or in combination with methotrexate (MTX). Preventive CCR2/CCL2 axis blockade in vivo reduced bone resorption and OCP frequency, whereas combining with MTX treatment also decreased disease clinical score, number of active osteoclasts, and OCP differentiation potential. In conclusion, our study characterized the functional properties of two distinct OCP subsets in CIA, based on their CCR2 expression levels, implying that the CCR2^hi circulatory-like subset is specifically induced by arthritis. Signaling through the CCL2/CCR2 axis contributes to OCP homing in the inflamed joints and to their increased osteoclastogenic potential. Therefore, addition of CCL2/CCR2 blockade early in the course of arthritis is a promising approach to reduce bone pathology.

SUBMITTER: Flegar D

PROVIDER: S-EPMC8677701 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:IntroductionThe existence of different osteoclast progenitor (OCP) subsets has been confirmed by numerous studies. However, pathological inflammation-induced osteoclastogenesis remains incompletely understood. Detailed characterization of OCP subsets may elucidate the pathophysiology of increased osteoclast activity causing periarticular and systemic bone resorption in arthritis. In our study, we rely on previously defined OCP subsets categorized by the level of CCR2 expression as circulatory-like committed CCR2hi OCPs, which are substantially expanded in arthritis, and marrow-resident CCR2lo OCPs of immature phenotype and behavior.MethodsIn order to perform transcriptome characterization of those subsets in the context of collagen-induced arthritis (CIA), we sorted CCR2hi and CCR2lo periarticular bone marrow OCPs of control and arthritic mice, and performed next-generation RNA sequencing (n=4 for each group) to evaluate the differential gene expression profile using gene set enrichment analysis with further validation.ResultsA disparity between CCR2hi and CCR2lo subset transcriptomes (863 genes) was detected, with the enrichment of pathways for osteoclast differentiation, chemokine and NOD-like receptor signaling in the CCR2hi OCP subset, and ribosome biogenesis in eukaryotes and ribosome pathways in the CCR2lo OCP subset. The effect of intervention (CIA) within each subset was greater in CCR2hi (92 genes) than in CCR2lo (43 genes) OCPs. Genes associated with the osteoclastogenic pathway (Fcgr1, Socs3), and several genes involved in cell adhesion and migration (F11r, Cd38, Lrg1) identified the CCR2hi subset and distinguish CIA from control group, as validated by qPCR (n=6 for control mice, n=9 for CIA mice). The latter gene set showed a significant positive correlation with arthritis clinical score and frequency of CCR2hi OCPs. Protein-level validation by flow cytometry showed increased proportion of OCPs expressing F11r/CD321, CD38 and Lrg1 in CIA, indicating that they could be used as disease markers. Moreover, osteoclast pathway-identifying genes remained similarly expressed (Fcgr1) or even induced by several fold (Socs3) in preosteoclasts differentiated in vitro from CIA mice compared to pre-cultured levels, suggesting their importance for enhanced osteoclastogenesis of the CCR2hi OCPs in arthritis.ConclusionOur approach detected differentially expressed genes that could identify distinct subset of OCPs associated with arthritis as well as indicate possible therapeutic targets aimed to modulate osteoclast activity.

Project description:Background: Age-related macular degeneration (AMD) is the most common cause of progressive and irreversible blindness in developed countries. Although the pathogenesis is not fully understood, AMD is a multifactorial pathology with an accumulation of inflammatory components and macrophages and a strong genetic predisposition. Our purpose was to investigate the association between early AMD and CCL2 (rs1024611, rs4586, rs2857656) and CCR2 (rs1799865) single nucleotide polymorphisms (SNPs) and CCL2, CCR2 serum levels in a Lithuanian population. Methods: The study included 310 patients with early AMD and 384 healthy subjects. Genotyping of CCL2 rs1024611, rs4586, rs2857656, and CCR2 rs1799865 was performed using a real-time polymerase chain reaction method, while CCL2 and CCR2 chemokines serum concentrations were analyzed using an enzyme-linked immunosorbent assay. Results: We found that the G allele at CCL2 rs1024611 was more prevalent in the early AMD group than in controls (29.2% vs. 24.1%, p = 0.032). Similarly, the C allele in CCL2 rs2857656 is more common in the early AMD group than in controls (29.2% vs. 24.2%, p = 0.037). Binomial logistic regression revealed that each G allele in rs1024611 was associated with 1.3-fold increased odds of developing early AMD under the additive model (OR = 1.322; 95% CI: 1.032–1.697, p = 0.027) as was each C allele in rs2857656 under the additive model (OR = 1.314; 95% CI: 1.025–1.684, p = 0.031). Haplotype analysis revealed that the C-A-G haplotype of CCL2 SNPs was associated with 35% decreased odds of early AMD development. Further analysis showed elevated CCL2 serum levels in the group with early AMD compared to controls (median (IQR): 1181.6 (522.6) pg/mL vs. 879.9 (494.4) pg/mL, p = 0.013); however, there were no differences between CCR2 serum levels within groups. Conclusions: We found the associations between minor alleles at CCL2 rs1024611 and rs2857656, elevated CCL2 serum levels, and early AMD development.

Project description:Background: Activated hepatic stellate cells (aHSCs) regulate the function of immune cells during liver fibrosis. As major innate cells in the liver, macrophages have inducible plasticity. Nevertheless, the mechanisms through which aHSCs regulate macrophages' phenotype and function during liver fibrosis and cirrhosis remain unclear. In this study, we examined the immunoregulatory function of aHSCs during liver fibrosis and explored their role in regulating macrophage phenotype and function. Methods: A total of 96 patients with different stages of chronic hepatitis B-related liver fibrosis were recruited in the study. Metavir score system was used to evaluate the degree of fibrosis. The expression of hepatic CCL2 and M2 phenotype macrophage marker CD163 were detected by immunohistochemistry, and the relationship among hepatic CD163, CCL2, and fibrosis scores were also explored. In the in vitro model, the aHSCs isolated from human liver tissues and THP-1-derived M0-type macrophages (M0MΦ) were co-cultured to observe whether and how aHSCs regulate the phenotype and function of macrophages. To explore whether CCL2/CCR2 axis has a crucial role in macrophage phenotypic changes during liver fibrosis, we treated the M0MΦ with recombinant human CCL2 or its specific receptor antagonist INCB-3284. Furthermore, we used LX2 and TGF-β-activated LX2 to mimic the different activation statuses of aHSCs to further confirm our results. Results: In patients, the infiltration of M2 macrophages increased during the progression of liver fibrosis. Intriguingly, as a key molecule for aHSC chemotactic macrophage aggregation, CCL2 markedly up-regulated the expression of CD163 and CD206 on the macrophages, which was further confirmed by adding the CCR2 antagonist (INCB 3284) into the cell culture system. In addition, the TGF-β stimulated LX2 further confirmed that aHSCs up-regulate the expression of CD163 and CD206 on macrophages. LX2 stimulated with TGF-β could produce more CCL2 and up-regulate other M2 phenotype macrophage-specific markers, including IL-10, ARG-1, and CCR2 besides CD163 and CD206 at the gene level, indicating that the different activation status of aHSCs might affect the final phenotype and function of macrophages. Conclusions: The expression of the M2 macrophage marker increases during liver fibrosis progression and is associated with fibrosis severity. AHSCs can recruit macrophages through the CCL2/CCR2 pathway and induce M2 phenotypic transformation.

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Preventive CCL2/CCR2 Axis Blockade Suppresses Osteoclast Activity in a Mouse Model of Rheumatoid Arthritis by Reducing Homing of CCR2^hi Osteoclast Progenitors to the Affected Bone.

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Preventive CCL2/CCR2 Axis Blockade Suppresses Osteoclast Activity in a Mouse Model of Rheumatoid Arthritis by Reducing Homing of CCR2hi Osteoclast Progenitors to the Affected Bone.

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OmicsDI is part of the ELIXIR infrastructure

Tweets

Preventive CCL2/CCR2 Axis Blockade Suppresses Osteoclast Activity in a Mouse Model of Rheumatoid Arthritis by Reducing Homing of CCR2^hi Osteoclast Progenitors to the Affected Bone.