Impact of interleukin-21 in the pathogenesis of primary Sjogren's syndrome: increased serum levels of interleukin-21 and its expression in the labial salivary glands

Kang, Kwi Young,Kim, Hyun-Ok,Kwok, Seung-Ki,Ju, Ji Hyeon,Park, Kyung-Su,Sun, Dong-Il,Jhun, Joo Yeon,Oh, Hye Jwa,Park, Sung-Hwan,Kim, Ho-Youn BioMed Central 2011 ARTHRITIS RESEARCH AND THERAPY Vol.13 No.5

<P><B>Introduction</B></P><P>Interleukin (IL)-21 is a cytokine that controls the functional activity of effector T helper cells and the differentiation of Th17 cells, and promotes B-cell differentiation. To test whether IL-21 participates in the pathogenesis of primary Sjögren's syndrome (SS), serum IL-21 level was measured and IL-21 expression in the labial salivary glands (LSG) was examined.</P><P><B>Methods</B></P><P>Serum IL-21 levels in 40 primary SS, 40 rheumatoid arthritis (RA), and 38 systemic lupus erythematosus (SLE) patients and 20 healthy controls were measured. Serum IL-21 levels of SS patients were assessed for correlations with laboratory data, including anti-nuclear antibody, anti-Ro/La antibodies, globulin, immunoglobulin (Ig) class, and IgG subclass. LSGs from 16 primary SS and 4 controls with sicca symptoms were evaluated for IL-21 and IL-21 receptor (IL-21R) expression by immunohistochemistry. Confocal microscopy was performed to further characterize the IL-21 positive cells.</P><P><B>Results</B></P><P>Primary SS patients had significantly higher serum IL-21 levels than controls, and these increments correlated positively with levels of IgG, IgG1. Serum IgG1 levels correlated with anti-Ro antibody titers. Immunohistochemical analyses showed that lymphocytic foci and the periductal area of the LSGs from SS patients expressed high levels of IL-21 and lower levels of IL-21R, whereas the control LSGs showed minimal expression of both antigens. The more the lymphocyte infiltrated, IL-21expression in LSGs showed a tendency to increase. Confocal microscopic analyses revealed that IL-21 expressing infiltrating lymphocytes in the LSGs of SS patients also expressed CXCR5.</P><P><B>Conclusions</B></P><P>Primary SS is associated with high serum IL-21 levels that correlate positively with serum IgG, especially IgG1, levels. The expression of IL-21 is increased as more lymphocytes infiltrated in LSGs. These observations suggest that IL-21 may play an important role in primary SS pathogenesis.</P>

A Novel Small-Molecule Inhibitor Targeting the IL-6 Receptor β Subunit, Glycoprotein 130

Hong, Soon-Sun,Choi, Jung Ho,Lee, Sung Yoon,Park, Yeon-Hwa,Park, Kyung-Yeon,Lee, Joo Young,Kim, Juyoung,Gajulapati, Veeraswamy,Goo, Ja-Il,Singh, Sarbjit,Lee, Kyeong,Kim, Young-Kook,Im, So Hee,Ahn, Sun The American Association of Immunologists, Inc. 2015 JOURNAL OF IMMUNOLOGY Vol.195 No.1

<P>IL-6 is a major causative factor of inflammatory disease. Although IL-6 and its signaling pathways are promising targets, orally available small-molecule drugs specific for IL-6 have not been developed. To discover IL-6 antagonists, we screened our in-house chemical library and identified-LMT-28, a novel synthetic compound, as a candidate IL-6 blocker. The activity, mechanism of action, and direct molecular target of LMT-28 were investigated. A reporter gene assay showed that LMT-28 suppressed activation of STAT3 induced by IL-6, but not activation induced by leukemia inhibitory factor. In addition, LMT-28 downregulated IL-6-stimulated phosphorylation of STAT3, gp130, and JAK2 protein and substantially inhibited IL-6-dependent TF-1 cell proliferation. LMT-28 antagonized IL-6-induced TNF-alpha production in vivo. In pathologic models, oral administration of LMT-28 alleviated collagen-induced arthritis and acute pancreatitis in mice. Based on the observation of upstream IL-6 signal inhibition by LMT-28, we hypothesized IL-6, IL-6R alpha, or gp130 to be putative molecular targets. We subsequently demonstrated direct interaction of LMT-28 with gp130 and specific reduction of IL-6/IL-6R alpha complex binding to gp130 in the presence of LMT-28, which was measured by surface plasmon resonance analysis. Taken together, our data suggest that LMT-28 is a novel synthetic IL-6 inhibitor that functions through direct binding to gp130.</P>

Interleukin 17 (IL-17) Increases the Expression of Toll-like Receptor-2, 4, and 9 by Increasing IL-1β and IL-6 Production in Autoimmune Arthritis

LEE, JUN-HEE,CHO, MI-LA,KIM, JU-IN,MOON, YOUNG-MEE,OH, HYE-JWA,KIM, GEUN-TAE,RYU, SUN,BAEK, SEUNG-HOON,LEE, SUN-HEE,KIM, HO-YOUN,KIM, SUNG-IL The Journal of Rheumatology 2009 The Journal of rheumatology Vol.36 No.4

<B>Objective.</B><P>To examine the effect of interleukin 17 (IL-17) on the expression of Toll-like receptor (TLR)-2, 4, and 9 in collagen-induced arthritis (CIA) in mice.</P><B>Methods.</B><P>On Days 28 and 32 after induction of CIA in mice, phosphate-buffered saline (PBS group) or IL-17 (IL-17 group) was injected into both knee joints. On Day 35, mice were sacrificed. The severity of knee joint arthritis, synovial inflammation, and bone destruction was measured by a scoring system using macrography and histological analysis. Synovial expression of TLR-2, 4, 9, IL-17, IL-1ß, tumor necrosis factor-α (TNF-α), and IL-6 was determined by real-time PCR and immunohistochemistry. Synoviocytes of CIA mice were cultured with IL-17 and with neutralizing antibodies to cytokine, and the expression of TLR-2, 4, 9, IL-1ß, TNF-α, and IL-6 was determined by real-time RT-PCR.</P><B>Results.</B><P>In CIA mice, knee arthritis scores, synovial inflammation, bone destruction scores, and expression of synovial TLR-2, 4, and 9, IL-17, IL-1ß, TNF-α and IL-6 were higher in the IL-17 and PBS groups than in normal DBA1 mice. These variables were also significantly higher in the IL-17 group than in the PBS group. In CIA synoviocytes, IL-17 increased the expression of TLR-2, 4, and 9, and this effect was significantly alleviated by neutralizing antibodies to IL-17, IL-1ß, and IL-6.</P><B>Conclusion.</B><P>IL-17 aggravates joint inflammation and destruction, and increases the synovial expression of TLR-2, 4, and 9 by increasing IL-1ß and IL-6. These results imply that the IL-17-induced increase in expression of TLR-2, 4, and 9, and IL-1ß and IL-6 production are involved in the IL-17-induced aggravation of arthritis.</P>

The Correlation of Serum IL-12B Expression With Disease Activity in Patients With Inflammatory Bowel Disease

Lee, Hye Won,Chung, Sook Hee,Moon, Chang Mo,Che, Xiumei,Kim, Seung Won,Park, Soo Jung,Hong, Sung Pil,Kim, Tae Il,Kim, Won Ho,Cheon, Jae Hee Williams & Wilkins Co 2016 Medicine Vol.95 No.23

<▼1><P>Supplemental Digital Content is available in the text</P></▼1><▼2><P><B>Abstract</B></P><P>Genetic variants in <I>IL12B</I>, encoding the p40 subunit common in interleukin-12 (IL-12) and interleukin-23, were identified as the susceptibility loci for inflammatory bowel disease (IBD). This study aimed to identify the correlation of serum IL-12B expression with disease activity in patients with IBD and evaluate the possibility of IL-12B as a biomarker for assessing inflammatory status in IBD.</P><P>A total of 102 patients with IBD, including 38, 32, and 32 patients with Crohn's disease (CD), ulcerative colitis (UC), and intestinal Behçet's disease (intestinal BD), respectively, were included. The clinical and laboratory data from the patients were collected at the time of serum IL-12B measurement. Serum IL-12B levels were measured using an enzyme-linked immunosorbent assay.</P><P>The median IL-12B levels in patients with CD, UC, and intestinal BD were significantly higher than those in controls (1.87, 2.74, and 2.73 pg/mL, respectively, vs. 1.42 pg/mL, all <I>P</I> <0.05). IL-12B concentrations were associated with disease activity in patients with UC and intestinal BD but not in those with CD. IL-12B levels were increased with increasing disease activity in patients with UC (<I>P</I> <0.001). Likewise, patients with active intestinal BD had higher IL-12B levels than those without active disease (<I>P</I> = 0.008). IL-12B levels were correlated with the endoscopic disease activity of UC (<I>P</I> = 0.002) and intestinal BD (<I>P</I> = 0.001) but not that of CD.</P><P>Serum IL-12B levels were significantly correlated with clinical and endoscopic disease activity in patients with UC and intestinal BD, suggesting its potential use as a biomarker for assessing disease activity in these patients.</P></▼2>

담배 니코틴에 의한 사람 태아 성상세포에서 종양괴사인자(TNF-α)의 발현 억제작용

손일홍,이성익,양현덕,한선정,석승한,이재규,김재현,박주영,문형인,이성수,Son, Il-Hong,Lee, Sung-Ik,Yang, Hyun-Duk,Han, Sun-Jung,Suk, Seung-Han,Lee, Jai-Kyoo,Kim, Jae-Hyun,Park, Joo-Young,Moon, Hyung-In,Lee, Sung-Soo 대한화학회 2007 대한화학회지 Vol.51 No.3

니코틴은 사람 대식세포에서 interleukin 2 (IL-2)와 종양괴사인자 (tumor necrosis factor-alpha; TNF-α) 가 생성되는 것을 억제하는데, 이러한 억제작용은 cytokine 유전자 발현 중 전사단계에서 전사인자의 활성을 억제함으로써 일어난다. 이러한 니코틴의 면역반응 억제작용은 아프타성궤양 및 궤양성대장염, 알레르기성폐 포염, 건초열 등에서도 보고되고 있다. 만일 중추신경계에서도 위와 같은 니코틴의 면역억제 작용이 일어난 다면 다발성경화증과 같은 면역반응 매개질환의 치료에 새로운 전기가 마련될 수 있을 것이다. 본 연구에서 는 중추신경계의 여러 면역반응 매개질환의 병태생리에 대한 이해를 넓히고자, 이미 알려진 니코틴의 cytokine 생성억제가 사람 중추신경계의 성상세포에서도 일어남을 확인하고 그 억제기전을 밝히고자 하였다. 이를 위 하여 사람 태아 성상세포에 다양한 농도의 니코틴과 IL-1β를 처리한 다음 TNF-α mRNA의 발현 정도와 NF- κB의 활성을 비교, 분석하여 다음과 같은 결과를 얻었다. 1. 사람 태아 성상세포를 0.1-20 μg/ml의 니코틴으로 처리해 본 결과 10 μg/ml 이상의 농도에서 세포독성능이 나타나기 시작하였다. 2. 사람 태아 성상세포에 IL- 1β를 처리하면 2시간만에 TNF-α mRNA가 최대로 발현되었으며 그 이후로는 점진적으로 감소하였다. 3. 사 람 태아 성상세포를 1 및 0.1 μg/ml의 니코틴으로 전처리한 후 IL-1β로 자극한 군에서는 IL-1β 단독 처리군에 비해 TNF-α mRNA의 발현이 감소하는 양상을 보였다. 1 μg/ml의 니코틴을 처리한 경우에는 8시간 이후부터 TNF-α mRNA의 발현이 현저하게 감소하여 12시간에 최대로 감소하였다. 또한 0.1 μg/ml의 니코틴을 처리한 군에서는 24시간에 가장 현저하게 감소하였다. 4. 성상세포에 IL-1β로 처리한 군에서는 강력한 NF-κB의 활성 을 확인할 수 있었으며, 니코틴을 전처리하고 IL-1β 자극한 군에서는 NF-B의 활성이 감소하였다. 결론적으로 일정농도 이상의 니코틴은 세포독성효과를 나타내나 적정한 농도와 시간 경과후 니코틴은 사람 태아 성상세포에서 IL-1β에 의해 유도되는 TNF-α의 발현 감소를 유도하며, 이는 NF-κB의 활성을 감소시킴으로써 나타난다고 생각된다. The Tumor necrosis factor-α, (TNF-α), is involved in the pathogenesis of multiple sclerosis and contributes to the degeneration of oligodendrocytes as well as neurons. Nicotine has been found to have immunosuppressive and inflammation-suppressing effects. Astrocytes, the major glial cells in the CNS, are capable of producing TNF-α at both the mRNA and protein levels in response to interleukin-1 (IL-1) or TNF-α. Nicotine has been shown to influence glial cell functions. To order to explore the role of astrocytes in the production of TNF-α, astrocytes were pretreated with nicotine and are stimulated with IL-1β to determine their effects on TNF-α production. The results are as follows. Cytotoxic effects of nicotine on human fetal astrocytes were noted above 10 μg/ml of nicotine. The effect of IL-1β on TNF-α mRNA expression in primary cultured human fetal astrocytes was maximal at 2 h after IL- 1β(100 pg/ml) treatment. Human fetal astrocytes were pretreated with 0.1, 1, and 10 μg/ml of nicotine and then stimulated with IL-1β (100 pg/ml) for 2 h. The inhibitory effect of nicotine on expressions of TNF-α mRNA in human fetal astrocytes with pretreated 0.1 μg/ml of nicotine is first noted at 8 hr, and the inhibitory effect is maximal at 12 h. The inhibitory effect at 1 μg/ml of nicotine is inhibited maximal at 24 h. Nicotine at 0.1, 1 and 10 μg/ml concentrations significantly inhibits IL-1β-induced NF-κB activation. Collectively, this study indicates that nicotine might inhibit the expression of TNF-α in activated human fetal astrocytes.

류마티스 관절염 동물 모델에서 활막의 RANKL/OPG mRNA 발현 비율 및 IL-17의 효과

이준희 ( Jun Hee Lee ),김근태 ( Geun Tae Kim ),류선 ( Sun Ryu ),김주인 ( Ju In Kim ),백승훈 ( Seung Hoon Baek ),김성일 ( Sung Il Kim ) 대한류마티스학회 2006 대한류마티스학회지 Vol.13 No.2

Objective: To investigate the synovial mRNA expression of receptor activator of NFκB (RANK), RANK ligand (RANKL), osteoprotegerin (OPG) and RANKL/OPG mRNA expression ratio, and to evaluate the effects of IL-17 in experimental rheumatoid arthritis (RA) model. Methods: After induction of collagen-induced arthritis (CIA) by type II collagen in DBA1 mice, mice were anesthetized at day 28 and a small aperture in the skin of the knee was performed. Mice, in which arthritis of knee was present, were selected and divided into 3 groups, and phosphate-buffered saline (PBS group), IL-17 (IL-17 group) or anti-IL-17 monoclonal antibody (anti-IL-17 group) was injected to both knee joint at day 28 and 32. At day 35, mice were sacrificed and synovium of knee joints were isolated. Synovial mRNA expression of RANKL, RANK and OPG was assessed by real-time RT-PCR and immunohistochemical stain. Results: Synovial RANKL and RANK mRNA expressions were significantly different among IL-17, PBS, anti-IL-17 and normal group (IL-17>PBS>anti-IL-17>normal group), and synovial OPG mRNA expressions in PBS, IL-17 and anti-IL-17 group were significantly high than those in normal group, however, there was no significant difference among IL-17, PBS and anti-IL-17 group. RANKL/OPG mRNA ratio was significantly different among these groups (IL-17>PBS>anti-IL-17>normal group). In immunohistochemical stain, RANKL, RANK and OPG-positive cells were expressed at synovium. Conclusion: Synovial RANKL/OPG mRNA ratio was enhanced in CIA, and IL-17 induced higher RANKL/OPG ratio in the synovium of CIA, which was blocked by anti-IL-17 antibody. These results suggest that RANKL/OPG mRNA ratio play an important roles on bone destruction, and IL-17 may be actively involved in bone destruction by enhancing RANKL/OPG ratio in CIA model.

금은화, 연교, 포공영 혼합물의 항염증 작용에 관한 연구

최강민 ( Kang Min Choi ),전주현 ( Ju Hyun Jeon ),김은석 ( Eun Seok Kim ),성기정 ( Ki Jung Sung ),김영일 ( Young Il Kim ) 대전대학교 한의학연구소 2021 혜화의학회지 Vol.30 No.1

Objective : The purpose of this study is to investigate the inflammatory-control effects of Cheonghyeol-antidote complex(Lonicera japonica Thunberg, Forsythia viridissima Lindley, and Taraxacum platycarpum H. Dahlstedt complex, CHA) in LPS-induced RAW264.7 cell and mouse inflammation models. Method : For in vitro and in vivo experiment, Indicators such as cell viability, mRNA expression level(iNOS, IL-6, IL-1β, COX-2, TNF-a), Inflammatory factor production(NO, IL-6, IL-1β, TNF-a), and protein phosphorylation level(ERK, JNK, p38) were analyzed. For in vivo experiment, Indicators such as mRNA expression level(iNOS, IL-6, IL-1β, COX-2, TNF-a), Inflammatory factor production(IL-6, IL-1β, TNF-a), protein phosphorylation level(ERK, JNK, p38) and immune cell(white blood cell, lymphocyte) were analyzed. Results : 1. In vitro experiment In cell viability of CHA, CHA showed cell viability below 90% at concentrations of 400 μg / ml or more. In mRNA expression level, IL-6 and IL-1β showed a significant decrease at all concentrations except 25 μg / ml concentration, and iNOS, COX-2, and TNF-a showed a significant decrease at all concentrations of CHA compared to the control group. In inflammatory factor production, NO and TNF-a showed a significant decrease at all concentrations except 25 μg / ml concentration of CHA, and IL-1β showed a significant decrease at 100, 200 μg / ml concentration of CHA compared to the control group. IL-6 showed a significant decrease at all concentration of CHA compared to the control group. In protein phosphorylation level, ERK and p38 showed a significant decrease at all concentrations except 25 μg / ml concentration of CHA and JNK showed a significant decrease at all concentrations of CHA compared to control group. 2. In vivo experiment In mRNA expression level, iNOS, COX-2 and TNF-a showed a significant decrease in all administration groups of CHA compared to the control group. In Inflammatory factor production, IL-6, IL-1β and TNF-a showed a significant decrease in all the administration groups of CHA. In protein phosphorylation level, ERK, JNK, and p38 showed a significant decrease in all the administration groups of CHA. In the immune cells, leukocytes and lymphocytes showed a significant decrease in all the administration groups of CHA. Conclusions : This study shows that CHA has antioxidant and inflammatory-control effects on LPS-induced RAW264.7 cells. It is hoped that further research will be conducted on the individual mechanisms of Lonicera japonica Thunberg, Forsythia viridissima Lindley, and Taraxacum platycarpum H. Dahlstedt.

Expression of TLR2, TLR4, and TLR9 in dermatomyositis and polymyositis

Kim, Geun-Tae,Cho, Mi-La,Park, Young-Eun,Yoo, Wan Hee,Kim, Jung-Hee,Oh, Hye-Jwa,Kim, Dae-Sung,Baek, Seung-Hoon,Lee, Sun-Hee,Lee, Jun-Hee,Kim, Ho-Youn,Kim, Sung-Il Springer-Verlag 2010 CLINICAL RHEUMATOLOGY Vol.29 No.3

<P>The aim of this study was to investigate the expressions of Toll-like receptor (TLR) 2, TLR4, TLR9, and their correlations with the expression of cytokines that are associated with activation of CD4<SUP>+</SUP> T cells and inflammation including interferon γ (IFNγ), interleukin 4 (IL4), interleukin 17 (IL17), and tumor necrosis factor α (TNFα) in muscle tissues of patients with dermatomyositis (DM) and polymyositis (PM). The expressions of TLR2, TLR4, TLR9, IFNγ, IL4, IL17, and TNFα were measured by real-time reverse transcription–polymerase chain reaction in muscle tissues from 14 patients with DM and PM (nine patients with DM, five patients with PM) and three controls. The expressions of TLR2, TLR4, and TLR9 were also localized with immunohistochemistry. The expression levels of TLR2, TLR4, TLR9, IFNγ, IL4, IL17, and TNFα were significantly high in patients with DM and PM compared with those in the controls, and the expression levels of TLR4 and TLR9 had significant positive correlations with the expressions of IFNγ, IL4, IL17, and TNFα. Immunohistochemistry showed that TLR2, TLR4, and TLR9 were expressed by infiltrating cells of perimysium in DM, whereas they were expressed by infiltrating cells of endomysium in PM. These results suggest that the involvement of TLR4 and TLR9 in immunopathogenesis of DM and PM might be connected with activation of CD4<SUP>+</SUP> T cells.</P>

Prevalence and Risk Factors of Atrophic Gastritis and Intestinal Metaplasia in a Korean Population Without Significant Gastroduodenal Disease

Kim, Nayoung,Park, Young Soo,Cho, Sung-Il,Lee, Hye Seung,Choe, Gheeyoung,Kim, In Wook,Won, Yoo-Deok,Park, Ji Hyun,Kim, Joo Sung,Jung, Hyun Chae,Song, In Sung Wiley (Blackwell Publishing) 2008 Helicobacter Vol.13 No.4

<P>BACKGROUND AND AIM: The prevalence of gastric cancer and Helicobacter pylori infection is unacceptably high in Korea. This study was performed to evaluate the prevalence of atrophic gastritis (AG) and intestinal metaplasia (IM) and to identify their risk factors with respect to H. pylori virulence factors, and environmental and host factors, in Korean population without significant gastroduodenal disease. METHODS: The study cohort consisted of 389 subjects (> or = 16 years). AG and IM were scored histologically using the Sydney classification in the antrum and body, respectively. Prevalences and bacterial factors (i.e. cagA, vacA m1, and oipA), environmental factors (i.e. smoking and alcohol), and host factors (i.e. genetic polymorphisms of IL-1B-511, IL-1RN, TNF-A-308, IL-10-592, IL-10-819, IL-10-1082, IL-8-251, IL-6-572, GSTP1, p53 codon 72, and ALDH2) were evaluated. RESULTS: Prevalences of AG in the antrum and body were 42.5% and 20.1%, and those of IM were 28.6% and 21.2%, respectively. The presences of AG and IM were significantly higher in H. pylori-positive than in the H. pylori-negative subjects. Multivariate analysis showed that the risk factors for AG were H. pylori infection, age > or = 61 years, and cagA and vacA m1 positivity. For IM the risk factors were H. pylori infection, age > or = 61 years, a smoking history (rather than current smoking), strong spicy food, occupation (unemployed or nonprofessional vs. professional), and the presence of IL10-592 C/A as opposed to A/A. In addition, IL6-572 G carrier was found to have a protective effect against IM development as compared with C/C. CONCLUSION: H. pylori infection was most important risk factor of AG and IM. Bacterial factors were found to be important risk factor for AG but environmental and host factors were more important for IM.</P>

IL-15에 의한 류마티스관절염 환자 활막 섬유모세포에서의 SDF-1 유도

박영은 ( Young Eun Park ),김성일 ( Sung Il Kim ),박성후 ( Seong Hu Park ),백승훈 ( Seung Hoon Baek ),오혜좌 ( Hye Jwa Oh ),허양미 ( Yang Mi Heo ),조미라 ( Mi La Cho ) 대한류마티스학회 2010 대한류마티스학회지 Vol.17 No.3

Objective: Interleukin-15 (IL-15) recruits and activates synovial T cells, and IL-15 plays an important role in amplifying and perpetuating inflammation in the pathogenesis of rheumatoid arthritis (RA). Stromal cell-derived factor-1 (SDF-1) is a potent chemoattractant for memory T cells in the inflamed RA synovium. This study investigated the effect of IL-15 on SDF-1 production in RA fibroblast-like synoviocytes (FLS). Methods: The expressions of IL-15 and SDF-1 were determined from the synovium of patients with RA and osteoarthritis (OA) by performing immunohistochemistry. The expressions of SDF-1 was measured from the RA FLS that were cultured with IL-15 and IL-17 by real-time RT-PCR and ELISA. The SDF-1 expression was also measured, via ELISA, from the RA FLS stimulated by IL-15 together with the inhibitors of such intracellular signal molecules as phosphatidylinositol 3-kinase (PI 3-kinase, LY294002), STAT3 (AG490), MAP Kinase (PD98059), NF-κB (parthenolide) and activator protein 1 (AP-1, curcumin). Results: IL-15 and SDF-1 were mainly expressed in the RA synovium compared to that of the OA synovium. IL-15 increased the SDF-1 expressions and it, and had an additive effect with IL-17 on the SDF-1 expressions in the cultured RA FLS. The IL-15 induced increase of the SDF-1 expression in the cultured RA FLS was blocked by the inhibitors of PI 3-kinase, NF-κB and AP-1. Conclusion: The SDF-1 expression was increased in the RA synovium and it was up-regulated by IL-15 in the RA FLS through the PI 3-kinase, NF-κB, and AP-1 pathways. These results imply that the IL-15 induced increase of the SDF-1 expressions may be involved in the immunopathogenesis of RA.