Rheumatoid Arthritis: Lee ZH

Lee EY, Lee ZH, Song YW. · Division of Rheumatology, Department of Internal Medicine, Seoul National University College of Medicine, Republic of Korea. · Autoimmun Rev. · Pubmed #19105984 No free full text.

Abstract: CXCL10 is a 10 kDa protein, which is categorized functionally as a Th1-chemokine. It binds to the receptor CXCR3 and regulates immune responses through the activation and recruitment of leukocytes, such as, T cells, eosinophils, and monocytes. Recent reports have shown that serum and/or tissue expressions of CXCL10 are increased in various autoimmune diseases like rheumatoid arthritis (RA), systemic lupus rythematosus (SLE), Sjogren syndrome (SS), systemic sclerosis (SSc), and idiopathic inflammatory myopathy (IIM). Moreover, CXCL10 and CXCR3 may have important roles in leukocyte homing to inflamed tissues and in the perpetuation of inflammation, and therefore, tissue damage. Our recent study shows that CXCL10 also has a pathogenic role in bone destruction via receptor activator of NF-kappaB ligand (RANKL) induction in inflamed synovial tissue of RA. In addition to its chemotactic effect, CXCL10 may have pleiotropic functions. Further research on the function of this chemokine and interactions between CXCL10 and other cytokines and chemokines may provide therapeutic targets in various autoimmune diseases.

Kim HL, Cho YS, Choi H, Chun YS, Lee ZH, Park JW. · Department of Pharmacology, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-799, Republic of Korea. · Biochem Biophys Res Commun. · Pubmed #19013431 No free full text.

Abstract: Rheumatoid arthritis (RA) is known to be associated with increased risks of hypoxia-related diseases, whose progresses are critically determined by HIF-1alpha. The authors hypothesized that the hypoxia-related complications of RA are associated with HIF-1alpha deregulation by some factor(s) in RA serum. Arthritis was induced in female Lewis rats by injecting complete Freund's adjuvant. The effects of arthritic rat serum (ARS) on hypoxic responses were investigated by incubating Hep3B cells in ARS. In the presence of ARS, HIF-1alpha was down-regulated and inactivated under hypoxic conditions. ARS inactivated AKT and mTOR, which led to impaired HIF-1alpha protein synthesis. Furthermore, insulin was found to be deficient in ARS and insulin supplementation fully recovered HIF-1alpha synthesis with AKT and mTOR activation. These results suggest that HIF-1alpha deregulation by components in serum is responsible for the RA-associated aggravation of hypoxic diseases in extra-articular tissues.

Kwak HB, Sun HM, Ha H, Lee JH, Kim HN, Lee ZH. · Department of Anatomy, School of Medicine, Wonkwang University, Iksan 570-749, Korea. · Mol Cells. · Pubmed #18695355 No free full text.

Abstract: Osteoclasts are multinucleated cells with the unique ability to resorb bone. Elevated activity of these cells under pathologic conditions leads to the progression of bone erosion that occurs in osteoporosis, periodontal disease, and rheumatoid arthritis. Thus, the regulation of osteoclast apoptosis is important for bone homeostasis. In this study, we examined the effects of the Janus tyrosine kinase 2 specific inhibitor AG490 on osteoclast apoptosis. We found that AG490 greatly inhibited osteoclast apoptosis. AG490 stimulated the phosphorylation of Akt and ERK. Adenovirus-mediated expression of dominant negative (DN)-Akt and DN-Ras in osteoclasts inhibited the survival of osteoclasts despite the presence of AG490. Cytochrome c release during osteoclast apoptosis was inhibited by AG490 treatment, but this effect was inhibited in the presence of LY294002 or U0126. AG490 suppressed the proapoptotic proteins Bad and Bim, which was inhibited in osteoclasts infected with DN-Akt and DN-Ras adenovirus. In addition, constitutively active MEK and myristoylated-Akt adenovirus suppressed the cleavage of pro-caspase-9 and -3 and inhibited osteoclast apoptosis induced by etoposide. Taken together, our results suggest that AG490 inhibited cytochrome c release into the cytosol at least partly by inhibiting the pro-apoptotic proteins Bad and Bim, which in turn suppressed caspase-9 and -3 activation, thereby inhibiting osteoclast apoptosis.

Kwak HB, Ha H, Kim HN, Lee JH, Kim HS, Lee S, Kim HM, Kim JY, Kim HH, Song YW, Lee ZH. · Wonkwang University School of Medicine, Iksan, Republic of Korea. · Arthritis Rheum. · Pubmed #18438854 links to  free full text

Abstract: OBJECTIVE: Interferon-gamma-inducible protein 10 (IP-10; also called CXCL10), a chemokine important in the migration and proliferation of T cells, is induced in a wide variety of cell types. However, the role of IP-10 in rheumatoid arthritis (RA) remains largely unknown. The purpose of this study was to examine the potential role of IP-10 in bone resorption and RA through examination of a mouse model of collagen-induced arthritis (CIA). METHODS: The effects of IP-10 on mouse T cells during osteoclast differentiation were examined in migration assays. The bone-erosive activity of IP-10 was determined in vivo in a mouse model of CIA by histologic and immunostaining analyses. Cytokine levels in serum and culture medium were measured with sandwich enzyme-linked immunosorbent assays. RESULTS: Serum concentrations of IP-10 were significantly higher in mice with CIA than in control mice. RANKL greatly induced IP-10 expression in osteoclast precursors, but not in mature osteoclasts. IP-10 stimulated the expression of RANKL and tumor necrosis factor alpha (TNFalpha) in CD4+ T cells and induced osteoclastogenesis in cocultures of CD4+ T cells and osteoclast precursors. However, IP-10 did not induce RANKL or TNFalpha in CD8+ T cells. Treatment with neutralizing antibody to IP-10 significantly inhibited the infiltration of CD4+ T cells and F4/80+ macrophages into the synovium and attenuated bone destruction in mice with CIA. Furthermore, levels of RANKL and TNFalpha were inhibited by antibody to IP-10. Bone erosion was observed in mice infected with an IP-10 retrovirus. CONCLUSION: Our findings suggest that IP-10 plays a critical role in the infiltration of CD4+ T cells and F4/80+ macrophages into inflamed joints and causes bone destruction. Our results provide the first evidence that IP-10 contributes to the recruitment of inflammatory cells and is involved in bone erosion in inflamed joints.

Park CK, Kim HJ, Kwak HB, Lee TH, Bang MH, Kim CM, Lee Y, Chung DK, Baek NI, Kim J, Lee ZH, Kim HH. · Department of Cell and Developmental Biology, BK21 Program, Dental Research Institute, Seoul National University School of Dentistry, 28 Yeongon-Dong, Chongno-Gu, Seoul, 110-749, South Korea. · Int Immunopharmacol. · Pubmed #17920527 No free full text.

Abstract: Osteoclasts are responsible for bone lysis in several bone diseases such as osteoporosis and rheumatoid arthritis. Natural products from plants have been invaluable source in discovery of compounds for new therapies. In this study, we screened plant products for potential application to therapy for bone loss using a primary osteoclastogenesis culture system and found that extract of Stewartia koreana (SKE) had a strong inhibitory effect on osteoclast formation. To gain molecular insights, we examined the effect of SKE on signaling pathways and transcription factors stimulated by the osteoclast differentiation factor RANKL. SKE suppressed the induction of c-Fos and NFATc1 by RANKL. However, SKE did not inhibit NF-kappaB activation by RANKL. Among the MAPKs stimulated by RANKL, SKE significantly reduced the activation of ERK and p38. Therefore, the anti-osteoclastogenic effect of SKE is likely to be elicited by interference with RANKL signaling to ERK and p38, which mediate the induction of c-Fos and subsequently that of NFATc1. Consistent with the in vitro effect on osteoclast differentiation, SKE showed a great inhibitory effect on in vivo bone loss in LPS-challenged mice. Taken together, we demonstrated that SKE has inhibitory effects on osteoclast differentiation in vitro and confirmed its in vivo efficacy in prevention of inflammatory bone loss.

Kwak HB, Yang D, Ha H, Lee JH, Kim HN, Woo ER, Lee S, Kim HH, Lee ZH. · Department of Cell and Developmental Biology, School of Dentistry, DRI, and BK21 Program, Seoul National University, Seoul 110-749, Korea. · Exp Mol Med. · Pubmed #16819284 links to  free full text

Abstract: Bone is a dynamic tissue that is regulated by the activity of bone-resorbing osteoclasts and bone-forming osteoblasts. Excessive osteoclast formation causes diseases such as osteoporosis and rheumatoid arthritis. Natural substances may be useful as therapeutic drugs to prevent many diseases in humans because they avoid the many side effects of treatment with chemical compounds. Here we show that tanshinone IIA isolated from Salvia miltiorrhiza Bunge inhibits the receptor activator of NF-kappaB ligand (RANKL)-mediated osteoclast differentiation of osteoclast precursors. Tanshinone IIA suppressed the expression levels of c-Fos and NFATc1 induced by RANKL. However, retrovirus-mediated overexpression of c-Fos induced the expression of NFATc1 despite the presence of tanshinone IIA and reversed the inhibitory effect of tanshinone IIA on osteoclast differentiation. Also, the introduction of osteoclast precursors with the NFATc1 retrovirus led to osteoclast differentiation in the presence of tanshinone IIA. Our results suggest that tanshinone IIA may have a role as a therapeutic drug in the treatment of bone disease such as osteoporosis.