Platelets
ISSN: 0953-7104 (Print) 1369-1635 (Online) Journal homepage: http://www.tandfonline.com/loi/iplt20
Altered cytokine levels in pediatric ITP Margareta Jernås, Yu Hou, Frida Strömberg Célind, Linlin Shao, Qian Wang, Xiuli Ju, Karin Mellgren, Hans Wadenvik, Ming Hou & Bob Olsson To cite this article: Margareta Jernås, Yu Hou, Frida Strömberg Célind, Linlin Shao, Qian Wang, Xiuli Ju, Karin Mellgren, Hans Wadenvik, Ming Hou & Bob Olsson (2015) Altered cytokine levels in pediatric ITP, Platelets, 26:6, 589-592, DOI: 10.3109/09537104.2014.974526 To link to this article: http://dx.doi.org/10.3109/09537104.2014.974526
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http://informahealthcare.com/plt ISSN: 0953-7104 (print), 1369-1635 (electronic) Platelets, 2015; 26(6): 589–592 ! 2015 Informa UK Ltd. DOI: 10.3109/09537104.2014.974526
SHORT COMMUNICATION
Altered cytokine levels in pediatric ITP Margareta Jerna˚s1*, Yu Hou2*, Frida Stro¨mberg Ce´lind3, Linlin Shao4, Qian Wang6, Xiuli Ju7, Karin Mellgren3, Hans Wadenvik1, Ming Hou4,8, & Bob Olsson5 1
Department of Internal Medicine, University of Gothenburg, Gothenburg, Sweden, 2Medical College, Shandong University, Jinan, China, Department of Paediatrics, The Queen Silvia’s Hospital for Pediatric and Adolescents, Gothenburg, Sweden, 4Department of Hematology, Qilu Hospital, Shandong University, Jinan, China, 5Department of Psychiatry and Neurochemistry, University of Gothenburg, Gothenburg, Sweden, 6 Department of Clinical Laboratory, 7Department of Pediatrics, Qilu Hospital, Shandong University, Jinan, China, and 8Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Jinan, China
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Abstract
Keywords
Immune thrombocytopenia (ITP) is an autoimmune disease where platelets are destroyed prematurely. In the majority of children, the disease resolves, but in some, it becomes chronic. Cytokines are important mediators of the immune response and are known to be dysregulated in autoimmune diseases. Therefore, our aim was to investigate differences in plasma levels of cytokines between children with ITP and healthy controls. We had two cohorts of children: one Swedish with 18 children with ITP and seven healthy children and a second Chinese one with 58 children with ITP and 30 healthy children. Plasma levels of chemokine (C-X3-C motif) ligand 1 (CX3CL1), transforming growth factor b1 (TGF-b1), and interleukin 22 (IL-22) were analyzed in both cohorts using enzyme-linked immunosorbent assays (ELISAs). We found lower plasma levels of TGF-b1 and elevated levels of CX3CL1 and IL-22 in children with ITP compared with controls in both the Swedish and the Chinese cohort. In conclusion, all three cytokines differ between pediatric ITP and healthy controls and may, therefore, be potential biomarkers for the disease.
Cytokines, ITP, pediatrics
Introduction Immune thrombocytopenia (ITP) is an autoimmune disease where platelets are destroyed prematurely by autoantibody opsonization and subsequent phagocytosis in the reticuloendothelial system and directly by cytotoxic T-cells and complement activation [1–3]. In adults, ITP is usually a chronic disease, but in the majority of children, the disease resolves and less than 20% becomes chronic [4]. CD4+ T cells are critical effector cells in the initiation of adaptive immune responses. After antigen stimulation, primary CD4+ T cells activate, expand, and differentiate into different effector subsets termed T helper (Th) 1, Th2, and Th17 cells, characterized by the production of distinct cytokines and effector functions. We and others have shown that adult ITP patients during the active phase is associated with a Th1polarized immune response [5, 6] that is, secretion of interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-a). We have also shown that there are differences
*These authors contributed equally to this work. Correspondence: Bob Olsson, PhD, Department of Psychiatry and Neurochemistry, University of Gothenburg, V-house, Sahlgrenska University Hospital Mo¨lndal, SE-431 80 Mo¨lndal, Sweden. Tel: 46 31 3432406. Fax +46 31 3432426. E-mail: [email protected] Ming Hou, MD, PhD, Department of Haematology, Qilu Hospital, Shandong University, Jinan, China. E-mail: [email protected]
History Received 10 July 2014 Revised 29 September 2014 Accepted 6 October 2014 Published online 20 March 2015
in cytokine levels between children with newly diagnosed and chronic ITP [7]. Chemokine (C-X3-C motif) ligand 1 (CX3CL1), transforming growth factor b1 (TGF-b1), and interleukin 22 (IL-22) are cytokines that have been implicated in many forms of autoimmunity [6, 8–18]. To further characterize the cytokine response in ITP, we analyzed plasma levels of these cytokines in two independent cohorts of children with ITP and healthy children, who served as controls.
Patients and methods The study was approved by the Regional Ethics Committee in Gothenburg, Sweden, and the Medical Ethical Committee of Qilu Hospital, Shandong University, China. All participants provided informed consent in accordance with the Declaration of Helsinki. Blood was collected by standard venipuncture technique and EDTA-anticoagulated plasma was obtained by centrifugation and aliquots were stored at 80 C until analysis. The Swedish cohort consisted of 18 children with ITP (10 boys and 8 girls, age range 0.7–21.1 years). All except one were either treatment naı¨ve or untreated for at least 6 months before sampling (Supplementary Table 1). The Chinese cohort consisted of 58 pediatric ITP patients (36 boys and 22 girls, age range 0.2–18 years). All were medication naı¨ve or were untreated for at least 3 months before
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sampling (Supplementary Table 2). All included subjects in both cohorts met the published criteria for ITP [19]. The Swedish control group consisted of seven healthy children (six boys and one girl, age range 6.1–19.6 years) and the Chinese control group consisted of 30 healthy children (17 boys and 13 girls, age range 4.3–18 years). All controls from both cohorts had normal platelet count and no concurrent illness or treatment at the time of blood sampling. In the Swedish cohort, chemokine (C-X3-C motif) ligand 1 (CX3CL1), transforming growth factor b1 (TGF-b1), and interleukin 22 (IL-22) were analyzed in plasma with assays from R&D Systems (Minneapolis, MN). In the Chinese cohort, plasma levels of CX3CL1 were analyzed with an assay from R&D Systems (Minneapolis, MN) and concentrations of TGF-b1 and IL-22 with assays from eBioscience (San Diego, CA). Differences between ITP and controls were analyzed with the Mann–Whitney U test. All data are presented as mean ± SEM and p-values 0.05 were considered significant.
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Results We first analyzed plasma levels of TGF-b1, which is an important immunoregulatory cytokine, in the Swedish cohort and found lower levels in ITP compared with controls (Figure 1A). To replicate these results, first we analyzed TGF-b1 in a larger Chinese cohort and once more found lower levels in ITP compared with controls (Figure 1B). Second, we analyzed levels of the proinflammatory cytokine CX3CL1 in plasma from the Swedish cohort. The levels were significantly higher in children with ITP than in healthy children (Figure 1C). These findings were replicated in the Chinese cohort (Figure 1D). Third, we analyzed the pleiotropic cytokine IL-22. Precisely as with CX3CL1 we found increased plasma levels of IL-22 in children with ITP in the Swedish cohort (Figure 1E) and Figure 1. Plasma levels of TGF-b1, CX3CL1, and IL-22 in children with ITP compared with healthy controls. TGF-b1 levels in the Swedish (A) and Chinese (B) cohort. CX3XL1 levels in the Swedish (C) and Chinese (D) cohort. IL-22 levels in the Swedish (E) and Chinese (F) cohort. Data are presented as mean ± SEM. The Swedish cohort consists of 18 children with ITP and seven healthy children and the Chinese cohort of 58 pediatric ITP patients and 30 healthy children.
Platelets, 2015; 26(6): 589–592
again we could replicate the findings in the Chinese cohort (Figure 1F).
Discussion We found decreased plasma levels of TGF-b1 in children with ITP compared with healthy children in both the Swedish and the Chinese cohort. TGF-b1 is an important mediator of regulatory T-cells and is implicated in all forms of autoimmunity. This is illustrated in mice where total deficiency or deficiency in T-cells of TGF-b1 leads to multifocal inflammatory disease [10, 11]. Our data are in line with previous studies where low TGF-b1 levels have been reported in children with both newly diagnosed and chronic ITP and also in adults with ITP [6, 12–14]. Thus, all forms of ITP in both children and adults seem to be uniformly associated with low levels of TGF-b1 in the active phase of the disease. In contrast, remission either spontaneously acquired or through treatment with steroids or intravenous immunoglobulins leads to normalized TGF-b1 levels [6, 20]. CX3CL1 also known as the fractalkine was increased in both cohorts of ITP children compared with controls. CX3CL1 is anchored to the endothelium where it promotes platelet adhesion and degranulation. It also mediates leukocyte adhesion and diathesis. In addition to the membrane-bound form, CX3CL1 can also be cleaved and the soluble form is strongly chemotactic for monocytes and lymphocytes [21, 22]. Indeed, we have previously found increased levels of CX3CR1, which is the receptor for CX3CL1, in T-cells from adults with chronic ITP with a concomitant increase in T-cells in the bone marrow [23]. We have also shown that the levels of CX3CR1 are increased in T-cells from newly diagnosed children with ITP compared with children with chronic ITP [7]. Thus, both CX3CL1 and its receptor are implicated in ITP. Furthermore, both CX3CL1 and its receptor have been shown to be important in many other autoimmune
DOI: 10.3109/09537104.2014.974526
diseases and coronary artery disease [8, 9, 24, 25]. Thus, CX3CL1 is likely a central cytokine in ITP and autoimmunity in general. We found elevated plasma levels of IL-22 in both ITP cohorts compared with their respective controls. Especially, Th17 cells, but also other lymphocyte subsets, secrete IL-22 [26]. IL-22 plays a protective role in the defense against infections but is also involved in a number of autoimmune diseases such as rheumatoid arthritis, Crohn’s disease, systemic lupus erythematosus, and psoriasis [15–18]. We have previously found elevated levels of IL-22 in adults with chronic ITP [27]. Thus, IL-22 seems to be involved in both adult and pediatric ITP. In conclusion, we could show in two independent cohorts that pediatric ITP is associated with low plasma levels of TGF-b1 and increased levels of IL-22 and CX3CL1. Thus, these cytokines may be potential biomarkers of the disease.
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Declaration of interest The authors declare that they have no conflicts of interest. Work in the authors’ laboratory is supported by grants from the Swedish Federal Government under the LUA/ALF agreement, Samariten Foundation, Tai Shan Scholar Foundation, National Natural Science Foundation of China (Nos. 81070396, 81070408, 81070407, 81070411, 81100334, 81100335, 81100336, 81100348, 81101869, 81170475, 81200344, and 81270578), National Science Fund for Distinguished Young Scholars (No. 81125002), 973 Program (Nos. 2009CB521904 and 2011CB503906), State Program of National Natural Science Foundation of China for Innovative Research Group 2011–2013 (No. 81021001), National Public Health Grand Research Foundation (No. 201202017), Key Clinical Research Project of Public Health Ministry of China 2010–2012, Natural Science Foundation of Shandong Province (Nos. ZR2010HQ002, ZR2010CQ040, and Y2008C121), National Key Vocational School About Clinical Specialty for Blood Disorders, Clinical Medicine Center Foundation of Shandong Province, Leading Medical Professionals Foundation of Shandong Province, Outstanding Young Scientist Research Award Foundation of Shandong Province (Nos. BS2010YY024, BS2010YY039, BS2011SW013, and BS2011YY021), the Research Fund for the Doctoral Program of Higher Education of China (No. 20100131120058) and Independent Innovation Foundation of Shandong University (No. 26010172611135).
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8. Yajima N, Kasama T, Isozaki T, Odai T, Matsunawa M, Negishi M, Ide H, Kameoka Y, Hirohata S, Adachi M. Elevated levels of soluble fractalkine in active systemic lupus erythematosus: Potential involvement in neuropsychiatric manifestations. Arthritis Rheum 2005;52:1670–1675. 9. Ruth JH, Volin MV, Haines 3rd GK, Woodruff DC, Katschke Jr KJ, Woods JM, Park CC, Morel JC, Koch AE. Fractalkine, a novel chemokine in rheumatoid arthritis and in rat adjuvant-induced arthritis. Arthritis Rheum 2001;44:1568–1581. 10. Li MO, Wan YY, Flavell RA. T cell-produced transforming growth factor-beta1 controls T cell tolerance and regulates Th1- and Th17cell differentiation. Immunity 2007;26:579–591. 11. Shull MM, Ormsby I, Kier AB, Pawlowski S, Diebold RJ, Yin M, Allen R, Sidman C, Proetzel G, Calvin D, et al. Targeted disruption of the mouse transforming growth factor-beta 1 gene results in multifocal inflammatory disease. Nature 1992;359:693–699. 12. Andersson PO, Stockelberg D, Jacobsson S, Wadenvik H. A transforming growth factor-beta1-mediated bystander immune suppression could be associated with remission of chronic idiopathic thrombocytopenic purpura. Ann Hematol 2000;79:507–513. 13. Bao W, Bussel JB, Heck S, He W, Karpoff M, Boulad N, Yazdanbakhsh K. Improved regulatory T-cell activity in patients with chronic immune thrombocytopenia treated with thrombopoietic agents. Blood 2010;116:4639–4645. 14. Wang JD, Chang TK, Lin HK, Huang FL, Wang CJ, Lee HJ. Reduced expression of transforming growth factor-beta1 and correlated elevation of interleukin-17 and interferon-gamma in pediatric patients with chronic primary immune thrombocytopenia (ITP). Pediatr Blood Cancer 2011;57:636–640. 15. Brand S, Beigel F, Olszak T, Zitzmann K, Eichhorst ST, Otte JM, Diepolder H, Marquardt A, Jagla W, Popp A, et al. IL-22 is increased in active Crohn’s disease and promotes proinflammatory gene expression and intestinal epithelial cell migration. Am J Physiol Gastrointest Liver Physiol 2006;290:G827–G838. 16. Cheng F, Guo Z, Xu H, Yan D, Li Q. Decreased plasma IL22 levels, but not increased IL17 and IL23 levels, correlate with disease activity in patients with systemic lupus erythematosus. Ann Rheum Dis 2009;68:604–606. 17. Lo YH, Torii K, Saito C, Furuhashi T, Maeda A, Morita A. Serum IL-22 correlates with psoriatic severity and serum IL-6 correlates with susceptibility to phototherapy. J Dermatol Sci 2010;58: 225–227. 18. Zhang L, Li JM, Liu XG, Ma DX, Hu NW, Li YG, Li W, Hu Y, Yu S, Qu X, et al. Elevated Th22 cells correlated with Th17 cells in patients with rheumatoid arthritis. J Clin Immunol 2011;31: 606–614. 19. Rodeghiero F, Stasi R, Gernsheimer T, Michel M, Provan D, Arnold DM, Bussel JB, Cines DB, Chong BH, Cooper N, et al. Standardization of terminology, definitions and outcome criteria in immune thrombocytopenic purpura of adults and children: Report from an international working group. Blood 2009;113:2386–2393. 20. Guo C, Chu X, Shi Y, He W, Li L, Wang L, Wang Y, Peng J, Hou M. Correction of Th1-dominant cytokine profiles by high-dose dexamethasone in patients with chronic idiopathic thrombocytopenic purpura. J Clin Immunol 2007;27:557–562. 21. Ancuta P, Rao R, Moses A, Mehle A, Shaw SK, Luscinskas FW, Gabuzda D. Fractalkine preferentially mediates arrest and migration of CD16+ monocytes. J Exp Med 2003;197:1701–1707. 22. Imai T, Hieshima K, Haskell C, Baba M, Nagira M, Nishimura M, Kakizaki M, Takagi S, Nomiyama H, Schall TJ, et al. Identification and molecular characterization of fractalkine receptor CX3CR1, which mediates both leukocyte migration and adhesion. Cell 1997; 91:521–530. 23. Olsson B, Ridell B, Carlsson L, Jacobsson S, Wadenvik H. Recruitment of T cells into bone marrow of ITP patients possibly due to elevated expression of VLA-4 and CX3CR1. Blood 2008; 112:1078–1084. 24. Damas JK, Boullier A, Waehre T, Smith C, Sandberg WJ, Green S, Aukrust P, Quehenberger O. Expression of fractalkine (CX3CL1) and its receptor, CX3CR1, is elevated in coronary artery disease and is reduced during statin therapy. Arterioscler Thromb Vasc Biol 2005;25:2567–2572. 25. Matsunawa M, Isozaki T, Odai T, Yajima N, Takeuchi HT, Negishi M, Ide H, Adachi M, Kasama T. Increased serum levels of soluble fractalkine (CX3CL1) correlate with disease activity in rheumatoid vasculitis. Arthritis Rheum 2006;54:3408–3416.
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26. Liang SC, Tan XY, Luxenberg DP, Karim R, Dunussi-Joannopoulos K, Collins M, Fouser LA. Interleukin (IL)-22 and IL-17 are coexpressed by Th17 cells and cooperatively enhance expression of antimicrobial peptides. J Exp Med 2006;203:2271–2279.
27. Hu Y, Li H, Zhang L, Shan B, Xu X, Liu X, Xu S, Yu S, Ma D, Peng J, et al. Elevated profiles of Th22 cells and correlations with Th17 cells in patients with immune thrombocytopenia. Hum Immunol 2012;73:629–635.
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Supplementary material available online Supplementary Tables 1 and 2.
ISSN: 0953-7104 (Print) 1369-1635 (Online) Journal homepage: http://www.tandfonline.com/loi/iplt20
Altered cytokine levels in pediatric ITP Margareta Jernås, Yu Hou, Frida Strömberg Célind, Linlin Shao, Qian Wang, Xiuli Ju, Karin Mellgren, Hans Wadenvik, Ming Hou & Bob Olsson To cite this article: Margareta Jernås, Yu Hou, Frida Strömberg Célind, Linlin Shao, Qian Wang, Xiuli Ju, Karin Mellgren, Hans Wadenvik, Ming Hou & Bob Olsson (2015) Altered cytokine levels in pediatric ITP, Platelets, 26:6, 589-592, DOI: 10.3109/09537104.2014.974526 To link to this article: http://dx.doi.org/10.3109/09537104.2014.974526
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Published online: 25 Mar 2015.
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Article views: 39
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View Crossmark data
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=iplt20 Download by: [University of Otago]
Date: 23 September 2015, At: 01:25
http://informahealthcare.com/plt ISSN: 0953-7104 (print), 1369-1635 (electronic) Platelets, 2015; 26(6): 589–592 ! 2015 Informa UK Ltd. DOI: 10.3109/09537104.2014.974526
SHORT COMMUNICATION
Altered cytokine levels in pediatric ITP Margareta Jerna˚s1*, Yu Hou2*, Frida Stro¨mberg Ce´lind3, Linlin Shao4, Qian Wang6, Xiuli Ju7, Karin Mellgren3, Hans Wadenvik1, Ming Hou4,8, & Bob Olsson5 1
Department of Internal Medicine, University of Gothenburg, Gothenburg, Sweden, 2Medical College, Shandong University, Jinan, China, Department of Paediatrics, The Queen Silvia’s Hospital for Pediatric and Adolescents, Gothenburg, Sweden, 4Department of Hematology, Qilu Hospital, Shandong University, Jinan, China, 5Department of Psychiatry and Neurochemistry, University of Gothenburg, Gothenburg, Sweden, 6 Department of Clinical Laboratory, 7Department of Pediatrics, Qilu Hospital, Shandong University, Jinan, China, and 8Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Jinan, China
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Abstract
Keywords
Immune thrombocytopenia (ITP) is an autoimmune disease where platelets are destroyed prematurely. In the majority of children, the disease resolves, but in some, it becomes chronic. Cytokines are important mediators of the immune response and are known to be dysregulated in autoimmune diseases. Therefore, our aim was to investigate differences in plasma levels of cytokines between children with ITP and healthy controls. We had two cohorts of children: one Swedish with 18 children with ITP and seven healthy children and a second Chinese one with 58 children with ITP and 30 healthy children. Plasma levels of chemokine (C-X3-C motif) ligand 1 (CX3CL1), transforming growth factor b1 (TGF-b1), and interleukin 22 (IL-22) were analyzed in both cohorts using enzyme-linked immunosorbent assays (ELISAs). We found lower plasma levels of TGF-b1 and elevated levels of CX3CL1 and IL-22 in children with ITP compared with controls in both the Swedish and the Chinese cohort. In conclusion, all three cytokines differ between pediatric ITP and healthy controls and may, therefore, be potential biomarkers for the disease.
Cytokines, ITP, pediatrics
Introduction Immune thrombocytopenia (ITP) is an autoimmune disease where platelets are destroyed prematurely by autoantibody opsonization and subsequent phagocytosis in the reticuloendothelial system and directly by cytotoxic T-cells and complement activation [1–3]. In adults, ITP is usually a chronic disease, but in the majority of children, the disease resolves and less than 20% becomes chronic [4]. CD4+ T cells are critical effector cells in the initiation of adaptive immune responses. After antigen stimulation, primary CD4+ T cells activate, expand, and differentiate into different effector subsets termed T helper (Th) 1, Th2, and Th17 cells, characterized by the production of distinct cytokines and effector functions. We and others have shown that adult ITP patients during the active phase is associated with a Th1polarized immune response [5, 6] that is, secretion of interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-a). We have also shown that there are differences
*These authors contributed equally to this work. Correspondence: Bob Olsson, PhD, Department of Psychiatry and Neurochemistry, University of Gothenburg, V-house, Sahlgrenska University Hospital Mo¨lndal, SE-431 80 Mo¨lndal, Sweden. Tel: 46 31 3432406. Fax +46 31 3432426. E-mail: [email protected] Ming Hou, MD, PhD, Department of Haematology, Qilu Hospital, Shandong University, Jinan, China. E-mail: [email protected]
History Received 10 July 2014 Revised 29 September 2014 Accepted 6 October 2014 Published online 20 March 2015
in cytokine levels between children with newly diagnosed and chronic ITP [7]. Chemokine (C-X3-C motif) ligand 1 (CX3CL1), transforming growth factor b1 (TGF-b1), and interleukin 22 (IL-22) are cytokines that have been implicated in many forms of autoimmunity [6, 8–18]. To further characterize the cytokine response in ITP, we analyzed plasma levels of these cytokines in two independent cohorts of children with ITP and healthy children, who served as controls.
Patients and methods The study was approved by the Regional Ethics Committee in Gothenburg, Sweden, and the Medical Ethical Committee of Qilu Hospital, Shandong University, China. All participants provided informed consent in accordance with the Declaration of Helsinki. Blood was collected by standard venipuncture technique and EDTA-anticoagulated plasma was obtained by centrifugation and aliquots were stored at 80 C until analysis. The Swedish cohort consisted of 18 children with ITP (10 boys and 8 girls, age range 0.7–21.1 years). All except one were either treatment naı¨ve or untreated for at least 6 months before sampling (Supplementary Table 1). The Chinese cohort consisted of 58 pediatric ITP patients (36 boys and 22 girls, age range 0.2–18 years). All were medication naı¨ve or were untreated for at least 3 months before
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sampling (Supplementary Table 2). All included subjects in both cohorts met the published criteria for ITP [19]. The Swedish control group consisted of seven healthy children (six boys and one girl, age range 6.1–19.6 years) and the Chinese control group consisted of 30 healthy children (17 boys and 13 girls, age range 4.3–18 years). All controls from both cohorts had normal platelet count and no concurrent illness or treatment at the time of blood sampling. In the Swedish cohort, chemokine (C-X3-C motif) ligand 1 (CX3CL1), transforming growth factor b1 (TGF-b1), and interleukin 22 (IL-22) were analyzed in plasma with assays from R&D Systems (Minneapolis, MN). In the Chinese cohort, plasma levels of CX3CL1 were analyzed with an assay from R&D Systems (Minneapolis, MN) and concentrations of TGF-b1 and IL-22 with assays from eBioscience (San Diego, CA). Differences between ITP and controls were analyzed with the Mann–Whitney U test. All data are presented as mean ± SEM and p-values 0.05 were considered significant.
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Results We first analyzed plasma levels of TGF-b1, which is an important immunoregulatory cytokine, in the Swedish cohort and found lower levels in ITP compared with controls (Figure 1A). To replicate these results, first we analyzed TGF-b1 in a larger Chinese cohort and once more found lower levels in ITP compared with controls (Figure 1B). Second, we analyzed levels of the proinflammatory cytokine CX3CL1 in plasma from the Swedish cohort. The levels were significantly higher in children with ITP than in healthy children (Figure 1C). These findings were replicated in the Chinese cohort (Figure 1D). Third, we analyzed the pleiotropic cytokine IL-22. Precisely as with CX3CL1 we found increased plasma levels of IL-22 in children with ITP in the Swedish cohort (Figure 1E) and Figure 1. Plasma levels of TGF-b1, CX3CL1, and IL-22 in children with ITP compared with healthy controls. TGF-b1 levels in the Swedish (A) and Chinese (B) cohort. CX3XL1 levels in the Swedish (C) and Chinese (D) cohort. IL-22 levels in the Swedish (E) and Chinese (F) cohort. Data are presented as mean ± SEM. The Swedish cohort consists of 18 children with ITP and seven healthy children and the Chinese cohort of 58 pediatric ITP patients and 30 healthy children.
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again we could replicate the findings in the Chinese cohort (Figure 1F).
Discussion We found decreased plasma levels of TGF-b1 in children with ITP compared with healthy children in both the Swedish and the Chinese cohort. TGF-b1 is an important mediator of regulatory T-cells and is implicated in all forms of autoimmunity. This is illustrated in mice where total deficiency or deficiency in T-cells of TGF-b1 leads to multifocal inflammatory disease [10, 11]. Our data are in line with previous studies where low TGF-b1 levels have been reported in children with both newly diagnosed and chronic ITP and also in adults with ITP [6, 12–14]. Thus, all forms of ITP in both children and adults seem to be uniformly associated with low levels of TGF-b1 in the active phase of the disease. In contrast, remission either spontaneously acquired or through treatment with steroids or intravenous immunoglobulins leads to normalized TGF-b1 levels [6, 20]. CX3CL1 also known as the fractalkine was increased in both cohorts of ITP children compared with controls. CX3CL1 is anchored to the endothelium where it promotes platelet adhesion and degranulation. It also mediates leukocyte adhesion and diathesis. In addition to the membrane-bound form, CX3CL1 can also be cleaved and the soluble form is strongly chemotactic for monocytes and lymphocytes [21, 22]. Indeed, we have previously found increased levels of CX3CR1, which is the receptor for CX3CL1, in T-cells from adults with chronic ITP with a concomitant increase in T-cells in the bone marrow [23]. We have also shown that the levels of CX3CR1 are increased in T-cells from newly diagnosed children with ITP compared with children with chronic ITP [7]. Thus, both CX3CL1 and its receptor are implicated in ITP. Furthermore, both CX3CL1 and its receptor have been shown to be important in many other autoimmune
DOI: 10.3109/09537104.2014.974526
diseases and coronary artery disease [8, 9, 24, 25]. Thus, CX3CL1 is likely a central cytokine in ITP and autoimmunity in general. We found elevated plasma levels of IL-22 in both ITP cohorts compared with their respective controls. Especially, Th17 cells, but also other lymphocyte subsets, secrete IL-22 [26]. IL-22 plays a protective role in the defense against infections but is also involved in a number of autoimmune diseases such as rheumatoid arthritis, Crohn’s disease, systemic lupus erythematosus, and psoriasis [15–18]. We have previously found elevated levels of IL-22 in adults with chronic ITP [27]. Thus, IL-22 seems to be involved in both adult and pediatric ITP. In conclusion, we could show in two independent cohorts that pediatric ITP is associated with low plasma levels of TGF-b1 and increased levels of IL-22 and CX3CL1. Thus, these cytokines may be potential biomarkers of the disease.
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Declaration of interest The authors declare that they have no conflicts of interest. Work in the authors’ laboratory is supported by grants from the Swedish Federal Government under the LUA/ALF agreement, Samariten Foundation, Tai Shan Scholar Foundation, National Natural Science Foundation of China (Nos. 81070396, 81070408, 81070407, 81070411, 81100334, 81100335, 81100336, 81100348, 81101869, 81170475, 81200344, and 81270578), National Science Fund for Distinguished Young Scholars (No. 81125002), 973 Program (Nos. 2009CB521904 and 2011CB503906), State Program of National Natural Science Foundation of China for Innovative Research Group 2011–2013 (No. 81021001), National Public Health Grand Research Foundation (No. 201202017), Key Clinical Research Project of Public Health Ministry of China 2010–2012, Natural Science Foundation of Shandong Province (Nos. ZR2010HQ002, ZR2010CQ040, and Y2008C121), National Key Vocational School About Clinical Specialty for Blood Disorders, Clinical Medicine Center Foundation of Shandong Province, Leading Medical Professionals Foundation of Shandong Province, Outstanding Young Scientist Research Award Foundation of Shandong Province (Nos. BS2010YY024, BS2010YY039, BS2011SW013, and BS2011YY021), the Research Fund for the Doctoral Program of Higher Education of China (No. 20100131120058) and Independent Innovation Foundation of Shandong University (No. 26010172611135).
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Supplementary material available online Supplementary Tables 1 and 2.
