骨是一種動態組織，由成骨細胞形成並被破骨細胞吸收，以因應機械負荷、血清鈣離子濃度，內分泌和神經元因子等變化。骨形成和吸收之間的不平衡將導致骨硬化或骨質疏鬆症。破骨細胞是源自單核細胞 - 巨噬細胞的造血前體巨型多核細胞。由於破骨細胞活性過度上升而導致的骨質流失在許多發炎性骨關節疾病中十分常見，例如風濕性關節炎（RA），化膿性關節炎和人工關節周圍骨溶解等。因此了解破骨細胞分化和功能的調節是治療這些疾病的重點之一。破骨細胞的形成需要許多因子，例如macrophage colony stimulating factor（M-CSF）和receptor activator of NF-κB ligand（RANKL）。 RANKL的表達受許多因素調節，包括發炎性因子。眾所周知，一氧化碳（CO）是一種普遍存在的空氣污染物，因為它對血紅蛋白的親和力是氧氣的240倍，因此導致缺氧和死亡。然而，已證明低濃度CO可用於抗氧化，抗增生和抗發炎反應。 CO釋放粒子還可以減少老鼠關節炎模型中的RANKL表現和骨侵蝕。這些先前的結果意味著CO可能在一定程度上影響破骨細胞生成。本論文的目的是：（1）通過鼠單核細胞系建立破骨細胞生成模型（2）研究CO是否真正可對破骨細胞生成造成影響，（3）探討其可能的機轉。我們預計這項研究可能會揭示CO的一些新的治療可能。

Bone is a dynamic tissue that is continuously formed by osteoblasts and resorbed by osteoclasts in response to changes in mechanical loading, altered serum calcium levels and a wide range of paracrine, endocrine and neuronal factors. Any unbalances between bone formation and resorption will lead to diseases such as osteopetrosis or osteoporosis. The principle bone-resorbing osteoclasts are giant multinucleated cells derived from hematopoietic precursors of the monocyte-macrophage lineage. Bone loss due to osteoclasts over activity is very common in many inflammatory bone disorders such as rheumatic arthritis (RA), septic arthritis and periprosthetic osteolysis. Thus, understanding of the regulation of osteoclasts differentiation and function is central to the treatment these diseases. Formation of functional and mature osteoclasts requires many factors such as macrophage colony stimulating factor (M-CSF) and receptor activator of NF-κB ligand (RANKL). The expression of RANKL is regulated by many factors including inflammatory cytokines. Carbon monoxide (CO), a ubiquitous air pollutant, has been well known as toxic because its affinity to hemoglobin is 240 times compares with oxygen thus causing hypoxia and death. However, low concentration CO has been proved to be useful in anti-oxidative stress, anti-proliferation and anti-inflammation in vivo and in vitro. CO releasing molecule can also reduce RANKL expression and bone erosion in murine collagen-induced arthritis model. These previous results imply that CO might affect osteoclastogenesis to a certain extent. The aims of this proposal are: (1) to set up an osteoclastogenesis model by the murine monocytic cell line, RAW 264.7 cells, stimulated with RANKL, (2) to investigate the effects of CO on osteoclastogenesis, (3) to explore the possible molecules mediating the effects of CO. We expect this study will probably reveal some novel therapeutic implication of CO.

Contents 3
Abstract 5
Introduction 7
Hypothesis 13
Experimental designs and preliminary results 17
Discussion 21
Future work 23
Materials and Methods 25
Figure legends 29
References: 37

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