ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 2131

Role of LECT2 in the Regulation of Bone Metabolism In Vitro and In Vivo

Myeung-Su Lee1, Chang-hoon Lee2, CHONG HYUK CHUNG1, Ju-Young Kim3, Yoon-Hee Cheon4, So Young Eun3 and Gyeung Do Park3, 1Wonkwang University Hospital, Iksan, South Korea, 2Wonkwang University Hospital, Iksan Jeonbuk, South Korea, 3Musculoskeletal and Immune Disease Research Institute, School of Medicine, Wonkwang University, Iksan, Republic of Korea, 4Musculoskeletal and Immune Disease Research Institute, School of Medicine, Wonkwang University, Iksan, Cholla-bukto, Republic of Korea

Meeting: ACR Convergence 2024

Keywords: , ,

Session Information

Date: Monday, November 18, 2024

Title: Osteoporosis & Metabolic Bone Disease – Basic & Clinical Science Poster

Session Type: Poster Session C

Session Time: 10:30AM-12:30PM

Background/Purpose: Leucocyte cell derived chemotaxin 2 (LECT2) is a hepatokine produced in liver cells, secreted into the circulation, and acts as a hormone throughout the body. It is involved in the pathogenesis of several diseases such as liver disease, sepsis, degenerative arthritis, and rheumatoid arthritis. In addition, it is reported to be identical to chondromodulin-II, a cartilage regulator that stimulates and activates the proliferation of chondrocytes and osteoblasts. However, research on the role and mechanism of action of LECT2 on osteoblasts and osteoclasts that regulate bone metabolism has not been revealed.Therefore, in this study, we attempted to determine the cause of osteoporosis due to imbalance in bone metabolism in vivo by revealing the effect and mechanism of action of the LECT2 gene on bone metabolism.

Methods: The osteoclast differentiation effect of LECT2 was each evaluated by TRAP staining and dentin bone resorption assay using LECT2 recombinant protein and siRNA silencing, and the intracellular signaling pathway was examined through real-time quantitative RT-PCR and western blot analysis. Also, LECT2 gene-deficient mice were created to demonstrate the effect of LECT2 on bone metabolism in vivo, and osteological characteristics of LECT2 gene-deficient mice were confirmed through micro-CT and histological analysis.

Results: We found that LECT2 positively regulated the receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclast differentiation and bone resorption with no effects on osteoblast differentiation by performing gain- and loss-of-function studies. Based on the in vitro experimental results, an experiment was conducted comparing LECT2 gene-deficient mice with wild-type mice. It was confirmed through micro-CT and histological analysis that the bone loss phenomenon in mice deficient in the LECT2 gene was further increased. In addition, it was confirmed through TRAP staining and F-actin analysis that osteoclast differentiation in bone marrow cells of LECT2 gene-deficient mice further progressed by RANKL. Additionally, in LECT2 gene-deficient mice, phosphorylation of Akt, p38, JNK, ERK, IκB and PLCγ2 and mRNA expression of OC-STAMP, DC-STAMP, β3-integrin, MMP9, Atp6v0d2, Cathepsin K and OSCAR were significantly increased, and expression of c-Fos and NFATc1 was increased at both protein and mRNA levels.

Conclusion: As a result, the significance of the in vitro and in vivo results demonstrated that the LECT2 gene plays an important role in bone metabolism by regulating osteoclast differentiation and function, and that LECT2 has potential as a candidate for gene therapy related to bone diseases.

Supporting image 1

Figure. (A-C) Knockdown of LECT2 induces RANKL-mediated osteoclast differentiation. (A) mRNA expression level of LECT2 was evaluated by quantitative real time RT-PCR. (B) BMMs were transfected with negative control siRNA (siControl) and siRNA against LECT2 (siLECT2). The infected BMMs were cultured with M-CSF (30 ng/mL) and RANKL (100 ng/mL) for 4 days. After then, the cells were fixed, permeabilized, and stained with TRAP solution. (C) The TRAP-positive MNCs were counted as mature osteoclasts. (D,E) LECT2 knockdown increases bone resorbing activity without affecting survival of mature osteoclasts. (D) Mature osteoclasts transfected with siRNA negative control and siRNA against LECT2 from the co-culture system were seeded in a hydroxyapatite-coated plate for 24 h, and in dentin slices for 48 h. The plates were photographed under a light microscope. (E) Pit area in the hydroxyapatite-coated plate and dentin slices were quantified using Image-Pro Plus (Ver. 4.5) software. (F,G) LECT2 KO mice exhibit decreased bone mass. (F) 10-week-old LECT2 WT and LECT2 KO mice were sacrificed and radiographs of the longitudinal and transverse sections of the proximal femurs were obtained using a micro-CT scanner. (G) BV/TV, Tb.Th, Tb.Sp, BS/TS, Tb.N, and Total porosity of the femurs was determined by analyzing the micro-CT data. (H) Schematic model of bone metabolism regulated by LECT2.

Disclosures: M. Lee: None; C. Lee: None; C. CHUNG: None; J. Kim: None; Y. Cheon: None; S. Eun: None; G. Park: None.

To cite this abstract in AMA style:

Lee M, Lee C, CHUNG C, Kim J, Cheon Y, Eun S, Park G. Role of LECT2 in the Regulation of Bone Metabolism In Vitro and In Vivo [abstract]. Arthritis Rheumatol. 2024; 76 (suppl 9). https://acrabstracts.org/abstract/role-of-lect2-in-the-regulation-of-bone-metabolism-in-vitro-and-in-vivo/. Accessed .

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