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>

자궁내막증 병변에서의 Cytokine mRNA의 발현 양상

이택후(Taek Hoo Lee),김광수(Gwang Soo Kim),김일규(Il Gyu Kim),전상식(Sang Sik Chun),조영래(Young Lae Cho) 대한산부인과학회 1999 Obstetrics & Gynecology Science Vol.42 No.9

목적: 자궁내막증은 최근에 그 빈도가 급격하게 증가되고 있으나 아직까지 병인과 치료법이 확실하게 정립되지 못하고 있는 부인과 내분비의 대표적인 질환이다. 최근 들어서 자궁내막증 환자의 불임의 원인으로 cytokine이 밀접하게 관여됨이 밝혀지고 있고 자궁내막증의 병인으로 복강내로 역류된 월경혈에 의한 복강내의 국소적 염증에 대한 개체의 반응정도와 면역체계의 변화가 중요하게 인정되고 있으나 아직까지 정확한 기전은 밝혀져 있지 않기 때문에 이에 저자는 자궁내막증 환자의 복수 내에서의 cytokine의 정량측정과 골반내 자궁내막증 병변조직에서의 cytokine mRNA의 발현 양상을 조사하여 자궁내막증 환자의 병인분석을 시도하였다. 연구방법: 자궁내막증 진단을 받고 복강경 혹은 개복 수술을 받은 30명의 환자에서 총 60개의 자궁내막증 병변이라고 의심되는 조직을 채취하여 이를 RT-PCR법을 이용하여 Cytokine 유전자의 발현양상을 조사하였다. 또한 7례의 정상대조군과 23례의 자궁내막증 환자의 복수를 ELISA법을 이용하여 정량분석을 시도하였다. 결과: 자궁내막증 환자의 복수내에서 IL-6와 IL-10의 농도는 자궁내막증의 임상적 중증도에 따라서 의미있게 증가되어 있었으나 IFN-γ, TNF-α, IL-1β, 그리고 IL-5의 농도는 정상 대조군에 비해서 변화가 없었다. 모든 예의 심부 자궁내막증 병변조직과 표재성 자궁내막증 병변조직에서 IL-1β cytokine mRNA의 발현을 볼 수 있었다. IL-5와 IL-6은 표재성 병변 12개 중에서 각각 2개의 black lesion에서만 발현을 볼 수 있었으며 IL-10은 표재성 병변에서는 12개중 2개에서 그리고 심부성 병변에서는 8개중 1개의 조직에서만 발현되었다. IFN-γ는 표재성 병변에서는 전혀 발현이 없었으나 심부성 병변에서는 8개중 4개의 조직에서 발현이 되었으며 TNF-α는 표재성 병변에서는 red 및 black 병변에서 각각 1개의 조직에서만 발현이 되었으나 심부성 병변에서는 역시 8개중 4개의 조직에서 발현이 되었다. 결론: 표재성 병변이 골반강내에 착상하여 염증성 반응이 일어날 수 있는 원인이 제공되면 IL-1β 혹은 TNF-α같은 염증성 cytokine이 분비가 되며 이로 인해 생성되는 단핵세포의 chemotactic factor에 의해 대식세포의 증가와 활성화가 이루어지고 이어서 복강내에 IL-6 등의 cytokine이 증가되며 마지막으로 여러 가지 증가된 cytokine에 대한 반대 반응으로 IL-10이 증가됨을 추정할 수가 있겠으며 이러한 가정은 앞으로 cytokine을 이용한 치료적 응용의 기초적인 연구로서 중요한 의미를 제공할 수 있다고 하겠다. Objective: The pathogenesis of endometriosis is generally accepted that retrograde menstruation and alterations in the local pelvic immune environment. This study was performed to help elucidate what kind of role various cytokines might play in the pathogenesis of endometriosis. Method: Concentrations of peritoneal fluid cytokines were compared in 7 women with normal pelvic finding and 23 women with endometriosis by enzyme-linked immunosorbent assay(ELISA). The patterns of cytokine mRNA expression in 8 ovarian endometrioma and 12 superficial pelvic endometriosis lesions were investigated by reverse transcription-polymerase chain reaction(RT-PCR) amplification method. Result: Both IL-6 and IL-10 levels in peritoneal fluid specimens with endometriosis tended to be higher than normal. However, there were no significant differences between peritoneal fluid concentrations of IFN-γ, TNF-α, IL-1β, and IL-5 of women with and without endometriosis. The levels of IL-6 and IL-10 were significantly higher in peritoneal fluid of women with severe endometriosis compared to women with mild endometriosis. IL-1β mRNA was expressed in all of 8 deep and 12 superficial endometriosis lesions. IL-5 and IL-6 mRNA were expressed in only two black lesions respectively, however, both were not expressed in the all deep lesions. Expressions of IL-10 mRNA occurred in one red and one black lesion while this was expressed in only one of the deep lesions. TNF-α mRNA was expressed in one red and one black lesion of 12 superficial lesions compared with four of the deep lesions. There was the difference between kinds of increased cytokines in the peritoneal fluid and those of expressed cytokines in the endometriotic lesions of patients with endometriosis. Conclusion: This study supports the concept that local immunologic factors may be important in the pathogenesis and pathophysiology of endometriosis. The pattern of cytokine mRNA expression of endometriotic lesions would seem to indicate that proinflammatory cytokines such as IL-1β and TNF-α are responsible for the development or progression of endometriosis.

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.

IL-17A induces osteoblast differentiation by activating JAK2/STAT3 in ankylosing spondylitis

Jo, Sungsin,Wang, Sung Eun,Lee, Young Lim,Kang, Suman,Lee, Bitnara,Han, Jinil,Sung, Il-Hoon,Park, Ye-Soo,Bae, Sang-Cheol,Kim, Tae-Hwan BioMed Central 2018 Arthritis research & therapy Vol.20 No.-

<P><B>Background</B></P><P>IL-17A has recently emerged as a potential target that regulates the extensive inflammation and abnormal bone formation observed in ankylosing spondylitis (AS). Blocking IL-17A is expected to inhibit bony ankylosis. Here, we investigated the effects of anti IL-17A agents in AS.</P><P><B>Methods</B></P><P>TNFα, IL-17A, and IL-12/23 p40 levels in serum and synovial fluid from patients with ankylosing spondylitis (AS), rheumatoid arthritis (RA), osteoarthritis (OA), or healthy controls (HC) were measured by ELISA. Bone tissue samples were obtained at surgery from the facet joints of ten patients with AS and ten control (Ct) patients with noninflammatory spinal disease. The functional relevance of IL-17A, biological blockades, Janus kinase 2 (JAK2), and non-receptor tyrosine kinase was assessed in vitro with primary bone-derived cells (BdCs) and serum from patients with AS.</P><P><B>Results</B></P><P>Basal levels of IL-17A and IL-12/23 p40 in body fluids were elevated in patients with AS. JAK2 was also highly expressed in bone tissue and primary BdCs from patients with AS. Furthermore, addition of exogenous IL-17A to primary Ct-BdCs promoted the osteogenic stimulus-induced increase in ALP activity and mineralization. Intriguingly, blocking IL-17A with serum from patients with AS attenuated ALP activity and mineralization in both Ct and AS-BdCs by inhibiting JAK2 phosphorylation and downregulating osteoblast-involved genes. Moreover, JAK2 inhibitors effectively reduced JAK2-driven ALP activity and JAK2-mediated events.</P><P><B>Conclusions</B></P><P>Our findings indicate that IL-17A regulates osteoblast activity and differentiation via JAK2/STAT3 signaling. They shed light on AS pathogenesis and suggest new rational therapies for clinical AS ankylosis.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (10.1186/s13075-018-1582-3) contains supplementary material, which is available to authorized users.</P>

Decreased Pattern-Recognition Receptor-Mediated Cytokine mRNA Expression in Obese Children With Otitis Media With Effusion

Kim, Youn Jung,Cha, Sung Ho,Lee, Ho Yun,Lee, Sun Kyu,Chung, Hee Yong,Yeo, Joon Hyung,Kim, Young Il,Yeo, Seung Geun Korean Society of Otorhinolaryngology-Head and Nec 2014 Clinical and Experimental Otorhinolaryngology Vol.7 No.1

<P><B>Objectives</B></P><P>To assess innate and humoral immune responses in middle ear effusion of obese pediatric patients with otitis media with effusion (OME).</P><P><B>Methods</B></P><P>We evaluated 219 children with OME, of whom 21 were obese and 198 were non-obese. We compared the expression in middle ear effusion of mRNAs encoding toll-like receptors (TLR) 2, 4, 5, and 9; nucleotide-binding oligomerization domains (NOD) 1 and 2; retinoic acid-inducible gene (RIG)-I; interleukins (IL)-6, -10, and -12; interferon (IFN)-γ; and tumor necrosis factor (TNF)-α mRNAs. We also compared the expression of immunoglobulins IgG, IgA, and IgM and the bacterial detection rate in the two groups.</P><P><B>Results</B></P><P>TLR2-mediated expression of IL-6 mRNA, TLR4-mediated expression of IL-6 and IL-10 mRNA, TLR5-mediated expression of IL-6, IL-10, and TNF-α mRNA, TLR9-mediated expression of IL-6 mRNA, and NOD2-mediated expression of IL-6, IL-12, and TNF-α mRNA were significantly lower in obese than in non-obese children (<I>P</I><0.05). However, concentrations of IgG, IgA, and IgM in middle ear effusion were lower in obese than in non-obese children, but none of these differences was significant (<I>P</I>>0.05).</P><P><B>Conclusion</B></P><P>Mean body mass index was higher and pattern-recognition receptor-mediated cytokine mRNA expression was lower in obese than in non-obese children with OME.</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.

Two-Track Medical Treatment Strategy According to the Clinical Scoring System for Chronic Rhinosinusitis

Kim, Dong-Kyu,Kang, Seong Il,Kong, Il Gyu,Cho, Young Hoon,Song, Seul Ki,Hyun, Se Jin,Cho, Sung Dong,Han, Sang-Yoon,Cho, Seong-Ho,Kim, Dae Woo The Korean Academy of Asthma, Allergy and Clinical 2018 Allergy, Asthma & Immunology Research Vol.10 No.5

<P><B>Purpose</B></P><P>The previously reported Japanese clinical scoring study (JESREC) suggests that chronic rhinosinusitis (CRS) can be divided into 4 subtypes according to the degree of eosinophilic CRS (ECRS) and offers the information regarding the prognosis of CRS to clinicians. However, this scoring system has not yet been validated by an immunological study and needs to provide treatment guidelines based on underlying immunologic profiles. We investigated the immunologic profile of each CRS subgroup according to the JESREC classification and suggest its clinical application.</P><P><B>Methods</B></P><P>A total of 140 CRS patients and 20 control subjects were enrolled. All patients were classified into 4 groups according to the JESREC (non-, mild, moderate and severe ECRS). Nasal tissues were analyzed for mRNA expression of major cytokines (IL-5, IL-10, IL-13, IL-17A, IL-22, IL-23p19, IFN-γ, periostin, thymic stromal lymphopoietin [TSLP] and ST2), major chemokines (CCL11, CCL24, CXCL1 and CXCL2), transcription factors (T-bet, GATA3, RORC and FOXP3) and COL1A1 for type I collagen. Protein levels of 3 major cytokines (IL-5, IL-17A and IFN-γ) were also measured by multiplex immunoassay. Principal component analysis (PCA) was conducted to investigate the overall profile of multiple mediators.</P><P><B>Results</B></P><P>The moderate/severe ECRS showed up-regulation of type 2-related mediators (IL-5, IL-13, periostin, TSLP and ST-2), whereas INF-γ (type 1 cytokine) and CXCL1 (neutrophil chemokine) expressions were increased in non-/mild ECRS compared with moderate/severe ECRS. The JESREC classification reflected an immunological endotype. In PCA data, PCA1 indicates a relative type 2 profile, whereas PCA2 represents a type 1/type 17-related profile. In this analysis, mild ECRS was indistinguishable from non-ECRS, whereas moderate to severe ECRS showed a distinct distribution compared with non-ECRS. The JESREC classification could be divided into 2 categories, non-/mild vs. moderate/severe ECRS based on underlying immunological analyses.</P><P><B>Conclusions</B></P><P>The CRS clinical scoring system from the JESREC study reflects an inflammatory endotype. However, the immunologic profile of mild ECRS was similar to that of non-ECRS. Therefore, we propose type 2-targeted medical treatment for moderate to severe ECRS and type 1/type 17-targeted for non-ECRS and mild ECRS as the first treatment option.</P>

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>

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>