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.

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>

The enhanced IL-l8 production by UVB irradiation requires ROI and AP-1 signaling in human keratinocyte cell line (HaCaT)

Cho, Daeho,Kang, Jae Seung,Park, Jong Hoon,Kim, Young-In,Hahm, Eunsil,Lee, Junechul,Yang, Yoolhee,Jeon, Junho,Song, HyunKeun,Park, Hyunjeong,Kim, Taesung,Pang, Saic,Kim, Chul-Woo,Hwang, Young Il,Lee, 전남대학교 약품개발연구소 2002 약품개발연구지 Vol.11 No.-

Based on our recent observation that enhanced IL-18 expression positively correlates with malignant skin tumors, such as SCC and melanoma, we examined the possible role of UVB, known to be associated with skin cancer development, in the enhancement of IL-18 production using primary human epidermal keratinocytes and human cell line HaCaT. After cells were exposed to UVB irradiation in vitro, IL-18 production was examined by Northern blot analysis and ELISA, and it was found that IL-18 production is enhanced by UVB irradiation in a dose- and time-dependent manner. In addition, we confirmed that it is functionally active form of IL-18 using the inhibitor of caspase-1. The effect of UVB irradiation was blocked by antioxidant, N-acetyl-ι-cysteine (NAC), which suggested the involvement of reactive oxygen intermediates (ROI) in the signal transduction of UVB irradiation-enhanced IL-18 synthesis. We also found that UVB irradiation increased AP-1 binding activity by using EMSA with AP-1-specific oligonucleotide. Furthermore, inhibitors of UVB-induced AP-1 activity, such as PD98059, blocked enhanced IL-18 production, indicating that AP-1 activation is required for UVB-induced IL-18 production. Taken together, our results suggest that UVB irradiation-enhanced IL-18 production is selectively mediated through the generation of ROI and the activation of AP-1.

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.

Activation of Transient Receptor Potential Melastatin Family Member 8 (TRPM8) Receptors Induces Proinflammatory Cytokine Expressions in Bronchial Epithelial Cells

김주희,Young Sook Jang,Hwan Il Kim,박지영,박성훈,Yong Il Hwang,Seung Hun Jang,Ki-Suck Jung,Hae Sim Park,Choon-Sik Park 대한천식알레르기학회 2020 Allergy, Asthma & Immunology Research Vol.12 No.4

Purpose: Cold air is a major environmental factor that exacerbates asthma. Transient receptor potential melastatin family member 8 (TRPM8) is a cold-sensing channel expressed in the airway epithelium. However, its role in airway inflammation remains unknown. We investigated the role of TRPM8 in innate immune responses in bronchial epithelial cells and asthmatic subjects. Methods: The TRPM8 mRNA and protein expression on BEAS2B human bronchial epithelial cells was examined by real-time polymerase chain reaction (PCR), immunofluorescence staining and western blotting. Additionally, interleukin (IL)-4, IL-6, IL-8, IL-13, IL-25 and thymic stromal lymphopoietin (TSLP) levels before and after menthol, dexamethasone and N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl) piperazine-1-carboxamide (BCTC) treatments were measured via real-time PCR. TRPM8 protein levels in the supernatants of induced sputum from asthmatic subjects and normal control subjects were measured using enzyme-linked immunosorbent assay, and mRNA levels in sputum cell lysates were measured using real-time PCR. Results: Treatment with up to 2 mM menthol dose-dependently increased TRPM8 mRNA and protein in BEAS2B cells compared to untreated cells (P < 0.001) and concomitantly increased IL-25 and TSLP mRNA (P < 0.05), but not IL-33 mRNA. BCTC (10 μM) significantly abolished menthol-induced up-regulation of TRPM8 mRNA and protein and IL-25 and TSLP mRNA (P < 0.01). TRPM8 protein levels were higher in the supernatants of induced sputum from asthmatic subjects (n = 107) than in those from healthy controls (n = 19) (P < 0.001), and IL-25, TSLP and IL-33 mRNA levels were concomitantly increased (P < 0.001). Additionally, TRPM8 mRNA levels correlated strongly with those of IL-25 and TSLP (P < 0.001), and TRPM8 protein levels were significantly higher in bronchodilator-responsive asthmatic subjects than in nonresponders. Conclusions: TRPM8 may be involved in the airway epithelial cell innate immune response and a molecular target for the treatment of asthma.

Soluble mediators from mesenchymal stem cells suppress T cell proliferation by inducing IL-10

Seung-Ha Yang,Min-Jung Park,Il-Hee Yoon,Su-Young Kim,So-Hee Hong,Jin-Young Shin,Hye-Young Nam,김용희,Bongi Kim,박정규 생화학분자생물학회 2009 Experimental and molecular medicine Vol.41 No.5

Mesenchymal stem cells (MSCs) can inhibit T cell proliferation; however, the underlying mechanisms are not clear. In this study, we investigated the mechanisms of the immunoregulatory activity of MSCs on T cells. Irradiated MSCs co-cultured with either naïve or pre-activated T cells in a mixed lymphocyte reaction (MLR) significantly suppressed T cell proliferation in a dose-dependent manner, irrespective of allogeneic disparity between responders and MSCs. Transwell assays revealed that the suppressive effect was primarily mediated by soluble factors that induced apoptosis. Splenocytes stimulated with alloantigen in the presence of the MSC culture supernatant (CS) produced a significant amount of IL-10, which was attributed to an increase in the number of IL-10 secreting cells, confirmed by an ELISPOT assay. The blockade of IL-10 and IL-10 receptor interaction by anti-IL-10 or anti-IL-10-receptor antibodies abrogated the suppressive capacity of MSC CS, indicating that IL-10 plays a major role in the suppression of T cell proliferation. The addition of 1-methyl-DL-tryptophan (1-MT), an indoleamine 2,3-dioxygenase (IDO) inhibitor, also restored the proliferative capacity of T cells. In conclusion, we demonstrated that soluble mediators from culture supernatant of MSCs could suppress the proliferation of both naïve and pre-activated T cells in which IL-10 and IDO play important roles.

DBA/1JCrj Mouse에 있어서 콜라젠유도관절염에 관한 면역학적 고찰

박승규,이지연,정일엽,최용경,최인성,김효준 大韓免疫學會 1996 大韓免疫學會誌 Vol.18 No.3

There is growing evidence that a variety of cytokines are secreted by cells at the inflammation sites of rheumatoid arthritis (RA) and that CDS+ B cell, a minor subtype of B cell population producing natural autoantibodies, is implicated in pathogenesis of RA. In this study, we evaluated the both cytokne levels and change of CDS+ B cell population in the peripheral blood from DBA/lJCrj mice(H-2`) which are collagen-induced arthritis(CIA) susceptible strain. Surprisingly, the healthy DBA/1JCrj and MRL/Ipr/Ipr(H-2'`) mice which were autoimmune susceptible strains tested in this experiment, showed lower IL-4, IL-6 and IL-10 levels in serum by 60% than heal-thy normal mouse strains such as Balb/c(H-2d), C57BL/6(H-2') and outbred ICR mice. MRL/lpr/ 1pr mice in which onset of spontaneous autoimmune disease is dependent upon age were similar to healthy DBA/1JCrj mice in levels of the cytokines in the serum when they are young. After the CIA(for DBA/1JCrj) or the spontaneous autoimmune disease(for MRL/lpr/Ipr) had been developed in the susceptible mouse strains, the levels of IL-6 and IL-4 in the serum were increased to 1.8- and 13-fold, respectively, as compaired with those from control groups while level of IL-10 remained relatively constant. The elevated levels of IL-4- and IL-6, however, in the serum from mice with disease status were still below those of the healthy normal mouse strains. On the other hand, CDS+ B cell population in the peripheral blood, which were reported to be increased with the development of RA for human, was rather significantly decreased for the CIA-induced DBA/lJCrj mice as evidenced by FACS analysis. It could be due to the differences in the pathogenic mechanism between CIA and RA. Taken together, our results. suggest that the levels of both these cytokines and CDS+ B cells may be utilized as important diagnostic markers for arthritides.

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>

Ownership Structure of Northeast Asian Countries

Seung Rok Park,Peter Drysdale,Shin Il Kang,In kie Hong 한국경제연구원 2004 한국경제연구원 연구보고서 Vol.2004-02 No.-

1 In the first paper “Determinants of Corporate Ownership Structure and their effects on Corporate Governance in South Korea” by Shin-Il Kang, Korea’s unique characteristics, specifically the ownership structure and corporate governance are examined. The author takes a broad perspective by incorporating corporate culture, business leadership, and ownership structure in Korean corporation. Furthermore, he discusses the substitutability of Korean specific features given the rapidly changing economic environment. Under the Korea’s Chaebol structure, controlling shareholders, who are the real owner of firms, have exercised ownership rights while having a large proportion of shares aided by cross shareholdings. This has been possible through the pyramid ownership control structure as well as cross-shareholding among subsidiaries. Market circumstances related to management costs are not favorable to the firm with a dispersed ownership structure. In Korea, that’s the reason why ownership is concentrated. Given such a structure, the owners minimize costs related to management’s risks. Furthermore it proposes that leadership(firm culture) and ownership are substitutes. Concentrated ownership is needed when the leadership is not mature like Korean Chaebol. 2 The second paper “Issues in Japanese Corporate Governance” by Peter Drysdale examines some of the major issues of Japanese corporate governance today. The role of that main bank in corporate governance and inter corporate shareholding has been well documented. Although Japanese banks have rigorously monitored firms and have had an enormous influence on firms’ decisions and strategies through the owning of shares, firm performance under such a main bank system has not always been positive. Opposing views and their rationale regarding the pessimism behind the performance of firms in the main bank system are also explained in this paper. 3 The paper “Corporate Governance in China” by In Kie Hong discusses the current status and the restructuring efforts of China’s corporate governance. In China, state shareholders possess strong control rights over listed companies allowing them to exercise control even beyond their proportion of shareholding. Various governmental organizations(under the Communist Party) acting as representatives of the state as shareholders have influenced firms enormously, particularly regarding matters of organizing the board of directors as well as electing management. However since they have little incentives to manage state(national) assets and have insufficient capacity to monitor a large number of firms of which they are in charge, the principal-agent problem tends to prevail, which adds to the difficulties in preserving the value of state assets as well. 4 The last paper “Ownership Concentration and Corporate Performances in the Northeast Asian Countries” by Seung-Rok Park compares the relationship between corporate governance structure and corporate performance in Korea, Japan, and China by empirically examining the accounting corporate performances and technical efficiency measures. In the case of Korea, ownership concentration was shown to have positively affected all corporate accounting performance variables such as profit margin, return on shareholders’ funds, return on total assets, and return on capital employed. Furthermore, it was also found that ownership concentration positively affected corporate performance by helping improve the technical efficiency of firms. Unlike Korea, in Japan, there was no sign of a positive effect of ownership concentration on the accounting corporate performance and technical efficiency. Moreover, in the case of China, ownership concentration positively affected profit margin and return on total assets, while no positive effects of ownership concentration were found on return on capital employed and return on shareholders’ funds. It is shown in this study that the difference in the rel