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Gao L, He C, Yang A, Zhou H, Lu Q, Birge RB, Wu Y. Receptor tyrosine kinases Tyro3, Axl, and Mertk differentially contribute to antibody-induced arthritis. Cell Commun Signal 2023; 21:195. [PMID: 37537628 PMCID: PMC10398921 DOI: 10.1186/s12964-023-01133-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 04/20/2023] [Indexed: 08/05/2023] Open
Abstract
Tyro3, Axl, and Mertk (abbreviated TAMs) comprise a family of homologous type 1 receptor tyrosine kinases (RTKs) that have been implicated as inhibitory receptors that dampen inflammation, but their roles in the pathogenesis of rheumatoid arthritis remains understudied. Here, to investigate TAMs in an inflammatory arthritis model, antibody-induced arthritis in single TAM-deficient mice (Tyro3- KO, Axl-KO, Mertk-KO) was induced by K/BxN serum injection. Subsequently, joint inflammation and cytokine levels, as well as the expression of Fcγ Rs and complement receptors were assessed in WT and TAM-deficient mice. Compared with littermate control mice, Axl-/- and Mertk-/- mice developed more severe antibody-induced arthritis, while in contrast, Tyro3-/- mice showed diminished joint inflammation. Concomitantly, the levels of cytokines in joints of Axl-/- and Mertk-/- mice were also significantly increased, while cytokines in the Tyro3-/- joint tissues were decreased. At the molecular and cellular level, TAMs showed distinct expression patterns, whereby monocytes expressed Axl and Mertk, but no Tyro3, while neutrophils expressed Axl and Tyro3 but little Mertk. Moreover, expression of Fcγ receptors and C5aR showed different patterns with TAMs expression, whereby FcγRIV was higher in monocytes of Axl-/- and Mertk-/- mice compared to wild-type mice, while Tyro3-/- neutrophils showed lower expression levels of FcγRI, FcγRIII and FcγRIV. Finally, expression of C5aR was increased in Mertk-/- monocytes, and was decreased in Tyro3-/- neutrophils. These data indicate that Axl, Mertk and Tyro3 have distinct functions in antibody-induced arthritis, due in part to the differential regulation of cytokines production, as well as expression of FcγRs and C5aR. Video Abstract.
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Affiliation(s)
- Liang Gao
- Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, National Clinical Research Center for Hematologic Diseases, Cyrus Tang Medical Institute, Soochow University, Suzhou, 215123, China
| | - Chao He
- Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, National Clinical Research Center for Hematologic Diseases, Cyrus Tang Medical Institute, Soochow University, Suzhou, 215123, China
| | - Aizhen Yang
- Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, National Clinical Research Center for Hematologic Diseases, Cyrus Tang Medical Institute, Soochow University, Suzhou, 215123, China.
| | - Haibin Zhou
- Department of Orthopaedics, The Second Affiliated Hospital of Soochow University, Suzhou, 215123, China
| | - Qingxian Lu
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, 40202, USA
| | - Raymond B Birge
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School Cancer Center, Rutgers University, Newark, NJ, USA.
| | - Yi Wu
- Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, National Clinical Research Center for Hematologic Diseases, Cyrus Tang Medical Institute, Soochow University, Suzhou, 215123, China.
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA.
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Li M, Xue W, Li X, Song Y, Liu X, Qin L. Axl is related to inflammation in hemodialysis patients. Mol Immunol 2021; 133:146-153. [PMID: 33667984 DOI: 10.1016/j.molimm.2021.02.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 02/10/2021] [Accepted: 02/23/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND Hemodialysis (HD) patients often develop chronic inflammation, which is associated with an increased risk of cardiovascular complications and mortality. Axl and its ligand, growth arrest 6 (Gas6), have been reported to play key roles in regulating the immune response. However, the function of Axl in HD patients has not been clarified. METHODS In the present study, we enrolled 130 HD patients and 117 normal controls (NCs) and evaluated the levels of inflammatory markers, soluble Axl (sAxl), membrane Axl (mAxl), and Gas6 in all participants. The potential downstream cascades of Gas6-Axl signaling in HD patients were identified by quantitative real time polymerase chain reaction and western blotting. RESULTS The levels of inflammatory cytokines-tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ)-plasma sAxl, and Gas6, were significantly increased in HD patients compared to NCs. Additionally, sAxl was positively associated with the inflammatory factor, interleukin-6 (IL-6), in HD patients. Moreover, we found that mAxl in CD14+ mononuclear cells and CD19+ B cells was increased upon HD. Furthermore, we discovered that the metalloproteinase ADAM17, also called TACE, contributed to the cleavage of mAxl into sAxl, and not ADAM10, in the peripheral blood mononuclear cells (PBMCs) of HD patients. The upregulation of Gas6-mAxl signaling caused the activation of the STAT1-SOCS3 pathway in the PBMCs of HD patients. After two years follow-up, patients with lower sAxl levels had longer survival time than those with higher sAxl levels. CONCLUSION Our results suggest that Axl may play a significant role in systemic inflammation in HD patients.
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Affiliation(s)
- Mengyuan Li
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai, 200072, China
| | - Wen Xue
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai, 200072, China
| | - Xinhua Li
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai, 200072, China
| | - Yaxiang Song
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai, 200072, China
| | - Xinying Liu
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai, 200072, China.
| | - Ling Qin
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai, 200072, China.
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New Insights into the Role of Tyro3, Axl, and Mer Receptors in Rheumatoid Arthritis. DISEASE MARKERS 2020; 2020:1614627. [PMID: 32051695 PMCID: PMC6995487 DOI: 10.1155/2020/1614627] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 12/01/2019] [Accepted: 01/04/2020] [Indexed: 12/14/2022]
Abstract
Rheumatoid Arthritis (RA) is the most common chronic inflammatory autoimmune disease involving joints. Among several pathogenic mechanisms, the impairment of homeostatic regulators of inflammation seems to be critically important to sustain persistent infiltration and activation of immune and stromal cells within the diseased synovium. Tyrosine kinase receptors Tyro3, Axl, and Mer are members of the TAM family. Upon binding their ligands Growth Arrest-Specific gene 6 (Gas6) and Protein S (ProS1), TAM receptors (TAMs) exert numerous and diverse biologic functions. Activated Axl and Mer, for instance, can negatively regulate the inflammatory cascade and mediate phagocytosis of apoptotic cells, contributing to prevent the development of autoimmunity. Thus, a role for TAMs has been hypothesized in RA. In this review, we will summarise unmet clinical needs in RA, depict the biology of TAMs and TAM ligands, focussing on their ability to regulate the immune system and inflammation cascade, and finally offer an overview of the state-of-the-art literature about the putative role of TAM axis in RA.
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Increased sMer, but not sAxl, sTyro3, and Gas6 relate with active disease in juvenile systemic lupus erythematosus. Clin Rheumatol 2019; 39:509-514. [PMID: 31655933 DOI: 10.1007/s10067-019-04799-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/04/2019] [Accepted: 09/23/2019] [Indexed: 10/25/2022]
Abstract
INTRODUCTION/OBJECTIVES Tyro3, Axl, and Mer (TAM) receptors and ligands mediate apoptotic bodies engulfment which alteration has been related with juvenile systemic lupus erythematosus (JSLE) pathogenesis. Thus, the aim was to determine their soluble levels. METHODS Serum sTyro3, sAxl, sMer, and Gas6 levels were measured using ELISA in 67 JSLE patients, 12 juvenile idiopathic arthritis (JIA) inflammatory and 20 healthy controls and related with SLEDAI-2K score, anti-dsDNA antibody, ESR, CRP, C3, C4 levels, and nephritis. RESULTS JSLE patients with active disease (SLEDAI-2K> 4) had significantly increased sMer levels compared with healthy controls (median 8.4 vs. 6.0 ng/mL, p = 0.009) and inactive disease patients (5.2 ng/mL, p = 0.0003). sMer levels correlated with SLEDAI-2K (r = 0.44; p = 0.0004) and ESR (r = 0.24; p = 0.04), while sAxl correlated with SLEDAI-2K (r = 0.33; p = 0.008) and C4 levels (r = - 0.24; p = 0.04). JSLE patients taking glucocorticoid had increased sAxl and sMer levels. Moreover, sAxl correlated with sMer and sTyro3 levels. Patients with nephritis and those with focal or diffuse proliferative glomerulonephritis had these protein levels similar to healthy controls and patients without renal involvement. sTyro3 levels of JSLE patients taking glucocorticoid were decreased, and correlated with Gas6 and sAxl, while Gas6 levels correlated with age upon enrollment. JIA controls had protein levels similar to healthy controls and JSLE patients. CONCLUSIONS This study reinforces that sMer is increased in active JSLE patients, yet sMer and sAxl correlates with disease activity parameters, and their alterations are disease-specific. However, further studies are needed to determine exact roles of sTyro3 and Gas6 in disease pathogenesis. Key Points • sMer and sAxl serum levels are related with active disease in JSLE patients • sMer correlated with SLEDAI-2K score in JSLE • sTyro3, sAxl, sMer and Gas6 levels did not related with nephritis in JSLE patients • sTyro3 and Gas6 exact roles in JSLE are not established and further studies are needed.
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Jung JY, Lee SW, Kim HA, Suh CH. Plasma Free Protein S Is Correlated with Disease Activity, but not with Subclinical Atherosclerosis among Patients with Systemic Lupus Erythematosus: A Cross-Sectional Study. TOHOKU J EXP MED 2019; 249:1-7. [PMID: 31511453 DOI: 10.1620/tjem.249.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A defect in clearance of apoptotic materials is pivotal in the pathogenesis of systemic lupus erythematosus (SLE). Protein S participates in the removal of apoptotic remnants and the anticoagulation pathway. The aim of the study was to clarify the relationship between plasma levels of free protein S and the disease activity or subclinical atherosclerosis in SLE. Free protein S was measured by an enzyme-linked immunosorbent assay, and patients were classified into two groups of free protein S levels: low (< 50%) and normal (≥ 50%). One hundred-eleven Korean female patients with SLE were enrolled, and the levels of free protein S were 67.4 ± 19.7%. Carotid plaque was detected in 25 (22.5%) patients. Twenty-one patients with low free protein S had lower hemoglobin (11.4 ± 1.4 vs. 12.5 ± 1.4 g/dL) and lymphocytes (1,221 ± 609 vs. 1,720 ± 1,097/µL), higher erythrocyte sedimentation rate (30.1 ± 20.6 vs. 20.8 ± 17.8 mm/h), and lower complement 3 (80.8 ± 27.6 vs. 103.4 ± 25.8 mg/dL) and complement 4 (15.6 ± 10.4 vs. 21.5 ± 7.6 mg/dL) than those with normal protein S. There was no significant difference in the proportion of patients with increased carotid artery intima-media thickness (> 4.6 mm) or with carotid artery plaque between two groups. The low levels of free protein S were associated with hemoglobin (OR = 0.64, p = 0.04) and complement 3 (OR = 0.96, p = 0.005). Free protein S is correlated with disease activity, but not with subclinical atherosclerosis in SLE.
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Affiliation(s)
- Ju-Yang Jung
- Department of Rheumatology, Ajou University School of Medicine
| | - Sang Won Lee
- Department of Rheumatology, Ajou University School of Medicine
| | - Hyoun-Ah Kim
- Department of Rheumatology, Ajou University School of Medicine
| | - Chang-Hee Suh
- Department of Rheumatology, Ajou University School of Medicine
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Gas6/TAM Receptors in Systemic Lupus Erythematosus. DISEASE MARKERS 2019; 2019:7838195. [PMID: 31360267 PMCID: PMC6652053 DOI: 10.1155/2019/7838195] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/14/2019] [Accepted: 06/25/2019] [Indexed: 01/25/2023]
Abstract
Systemic lupus erythematosus (SLE) is a multiorgan autoimmune disease associated with impaired immune system regulation. The exact mechanisms of SLE development remain to be elucidated. TAM receptor tyrosine kinases (RTKs) are important for apoptotic cell clearance, immune homeostasis, and resolution of immune responses. TAM deficiency leads to lupus-like autoimmune diseases. Activation of TAM receptors leads to proteolytic cleavage of the receptors, generating soluble forms of TAM. Circulating TAM receptors have an immunoregulatory function and may also serve as biomarkers for disease prognosis. Here, we review the biological function and signaling of TAM RTKs in the development and pathogenesis of lupus and lupus nephritis. Targeting Gas6/TAM pathways may be of therapeutic benefit. A discussion of potential TAM activation and inhibition in the treatment of lupus and lupus nephritis is included.
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Serum Axl predicts histology-based response to induction therapy and long-term renal outcome in lupus nephritis. PLoS One 2019; 14:e0212068. [PMID: 30742665 PMCID: PMC6370217 DOI: 10.1371/journal.pone.0212068] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/25/2019] [Indexed: 01/19/2023] Open
Abstract
Axl is a receptor tyrosine kinase with important functions in immune regulation. We investigated serum levels of soluble (s)Axl in lupus nephritis (LN) in association with renal disease activity, tissue damage and treatment response. We surveyed 52 patients with International Society of Nephrology/Renal Pathology Society (ISN/RPS) class III/IV LN and 20 healthy controls. Renal biopsies were performed at the time of active LN and post-treatment. Patients were classified as clinical responders (CRs) or clinical non-responders based on the American College of Rheumatology (ACR) criteria. Improvement by ≥50% in renal activity index scores defined histological responders (HRs). sAxl levels were elevated in patients compared to controls (median: 18.9 ng/mL), both at baseline (median: 45.7; P<0.001) and post-treatment (median: 41.2 ng/mL; P<0.001). Baseline sAxl levels were higher in patients with class IV (median: 47.7 ng/mL) versus class III (median: 37.5 ng/mL) nephritis (P = 0.008), and showed moderate correlations with albuminuria (r = 0.30, P = 0.030) and creatinine (r = 0.35, P = 0.010). Baseline sAxl levels decreased in CRs (P = 0.002) and HRs (P<0.001), but not in non-responders; levels ≥36.6 ng/mL yielded a >5 times higher probability of histology-based response (odds ratio, OR: 5.5; 95% confidence interval, CI: 1.2-25.1). High post-treatment sAxl levels were associated with worsening in chronicity index scores (P = 0.025); low levels predicted favourable renal outcome (creatinine ≤88.4 μmol/L) 10 years after the baseline renal biopsy (area under the curve: 0.71; 95% CI: 0.54-0.89). In conclusion, sAxl may prove useful as a marker of renal activity, histological response to immunosuppression, and renal damage progression in LN. Persistently high sAxl levels after completion of treatment may be indicative of a need for treatment intensification.
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8
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Mulla MJ, Weel IC, Potter JA, Gysler SM, Salmon JE, Peraçoli MTS, Rothlin CV, Chamley LW, Abrahams VM. Antiphospholipid Antibodies Inhibit Trophoblast Toll-Like Receptor and Inflammasome Negative Regulators. Arthritis Rheumatol 2018; 70:891-902. [PMID: 29342502 DOI: 10.1002/art.40416] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 01/09/2018] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Women with antiphospholipid antibodies (aPL) are at risk for pregnancy complications associated with poor placentation and placental inflammation. Although these antibodies are heterogeneous, some anti-β2 -glycoprotein I (anti-β2 GPI) antibodies can activate Toll-like receptor 4 (TLR-4) and NLRP3 in human first-trimester trophoblasts. The objective of this study was to determine the role of negative regulators of TLR and inflammasome function in aPL-induced trophoblast inflammation. METHODS Human trophoblasts were not treated or were treated with anti-β2 GPI aPL or control IgG in the presence or absence of the common TAM (TYRO3, AXL, and Mer tyrosine kinase [MERTK]) receptor ligand growth arrest-specific protein 6 (GAS6) or the autophagy-inducer rapamycin. The expression and function of the TAM receptor pathway and autophagy were measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blotting, and enzyme-linked immunosorbent assay (ELISA). Antiphospholipid antibody-induced trophoblast inflammation was measured by qRT-PCR, activity assays, and ELISA. RESULTS Anti-β2 GPI aPL inhibited trophoblast TAM receptor function by reducing cellular expression of the receptor tyrosine kinases AXL and MERTK and the ligand GAS6. The addition of GAS6 blocked the effects of aPL on the TLR-4-mediated interleukin-8 (IL-8) response. However, the NLRP3 inflammasome-mediated IL-1β response was not affected by GAS6, suggesting that another regulatory pathway was involved. Indeed, anti-β2 GPI aPL inhibited basal trophoblast autophagy, and reversing this with rapamycin inhibited aPL-induced inflammasome function and IL-1β secretion. CONCLUSION Basal TAM receptor function and autophagy may serve to inhibit trophoblast TLR and inflammasome function, respectively. Impairment of TAM receptor signaling and autophagy by anti-β2 GPI aPL may allow subsequent TLR and inflammasome activity, leading to a robust inflammatory response.
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Affiliation(s)
| | - Ingrid C Weel
- Yale University, New Haven, Connecticut, and São Paulo State University, São Paulo, Brazil
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Xu L, Hu F, Zhu H, Liu X, Shi L, Li Y, Zhong H, Su Y. Soluble TAM receptor tyrosine kinases in rheumatoid arthritis: correlation with disease activity and bone destruction. Clin Exp Immunol 2017; 192:95-103. [PMID: 29148078 DOI: 10.1111/cei.13082] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2017] [Indexed: 12/28/2022] Open
Abstract
The TAM receptor tyrosine kinases (TAM RTK) are a subfamily of receptor tyrosine kinases, the role of which in autoimmune diseases such as systemic lupus erythematosus has been well explored, while their functions in rheumatoid arthritis (RA) remain largely unknown. In this study, we investigated the role of soluble TAM receptor tyrosine kinases (sAxl/sMer/sTyro3) in patients with RA. A total of 306 RA patients, 100 osteoarthritis (OA) patients and 120 healthy controls (HCs) were enrolled into this study. The serum concentrations of sAxl/sMer/sTyro3 were measured by enzyme-linked immunosorbent assay (ELISA), then the associations between sAxl/sMer/sTyro3 levels and clinical features of RA patients were analysed. We also investigated whether sTyro3 could promote osteoclast differentiation in vitro in RA patients. The results showed that compared with healthy controls (HCs), sTyro3 levels in the serum of RA patients were elevated remarkably and sMer levels were decreased significantly, whereas there was no difference between HCs and RA patients on sAxl levels. The sTyro3 levels were correlated weakly but positively with white blood cells (WBC), immunoglobulin (Ig)M, rheumatoid factor (RF), swollen joint counts, tender joint counts, total sharp scores and joint erosion scores. Conversely, there were no significant correlations between sMer levels and the above indices. Moreover, RA patients with high disease activity also showed higher sTyro3 levels. In-vitro osteoclast differentiation assay showed further that tartrate-resistant acid phosphatase (TRAP)+ osteoclasts were increased significantly in the presence of sTyro3. Collectively, our study indicated that serum sTyro3 levels were elevated in RA patients and correlated positively with disease activity and bone destruction, which may serve as an important participant in RA pathogenesis.
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Affiliation(s)
- L Xu
- Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.,Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, China
| | - F Hu
- Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.,Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, China
| | - H Zhu
- Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.,Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, China
| | - X Liu
- Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.,Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, China
| | - L Shi
- Department of Rheumatology and Immunology, Peking University International Hospital, Beijing, China
| | - Y Li
- Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.,Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, China
| | - H Zhong
- Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.,Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, China
| | - Y Su
- Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.,Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Beijing, China
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Dengler M, Staufer K, Huber H, Stauber R, Bantel H, Weiss KH, Starlinger P, Pock H, Klöters-Plachky P, Gotthardt DN, Rauch P, Lackner C, Stift J, Brostjan C, Gruenberger T, Kumada T, Toyoda H, Tada T, Weiss TS, Trauner M, Mikulits W. Soluble Axl is an accurate biomarker of cirrhosis and hepatocellular carcinoma development: results from a large scale multicenter analysis. Oncotarget 2017; 8:46234-46248. [PMID: 28526812 PMCID: PMC5542263 DOI: 10.18632/oncotarget.17598] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 04/06/2017] [Indexed: 12/21/2022] Open
Abstract
Patients with chronic liver disease (CLD) and cirrhosis are at high risk for hepatocellular carcinoma (HCC). Current diagnostic tools for HCC detection include imaging techniques and serum biomarkers such as α-fetoprotein (AFP). Yet, these methods are limited in sensitivity and specificity to accurately detect early HCC. Here we focused on the potential of soluble Axl (sAxl) as a biomarker in CLD patients by analyzing serum samples of 1067 patients and healthy controls from centers in Europe and Asia. We show that serum concentrations of sAxl were significantly increased at early (82.57 ng/mL) and later stages of HCC (114.50 ng/mL) as compared to healthy controls (40.15 ng/mL). Notably, no elevated sAxl levels were detected in patients with CLD including chronic viral hepatitis, autoimmune hepatitis, cholestatic liver disease, or non-alcoholic fatty liver disease versus healthy controls. Furthermore, sAxl did not rise in liver adenomas or cholangiocarcinoma (CCA). Yet, patients with advanced fibrosis (F3) or cirrhosis (F4) showed enhanced sAxl concentrations (F3: 54.67 ng/mL; F4: 94.74 ng/mL). Hepatic myofibroblasts exhibited an increased release of sAxl, suggesting that elevated sAxl levels arise from these cells during fibrosis. Receiver operating characteristic curve analysis of sAxl displayed a strongly increased sensitivity and specificity to detect both cirrhosis (80.8%/92.0%) and HCC (83.3%/86.7%) with an area under the curve of 0.935/0.903 as compared to AFP. In conclusion, sAxl shows high diagnostic accuracy at early stage HCC as well as cirrhosis, thereby outperforming AFP. Importantly, sAxl remains normal in most common CLDs, liver adenomas and CCA.
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Affiliation(s)
- Mirko Dengler
- Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Center Vienna, Medical University of Vienna, Vienna, Austria
| | - Katharina Staufer
- Department of Surgery, Division of Transplantation, Medical University of Vienna, Vienna, Austria
- Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna, Vienna, Austria
| | - Heidemarie Huber
- Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Center Vienna, Medical University of Vienna, Vienna, Austria
| | - Rudolf Stauber
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Heike Bantel
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | | | - Patrick Starlinger
- Department of Surgery, Division of General Surgery, Medical University of Vienna, Vienna, Austria
| | - Hannelore Pock
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | | | | | - Peter Rauch
- Candor Bioscience GmbH, Wangen im Allgäu, Germany
| | - Carolin Lackner
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Judith Stift
- Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
| | - Christine Brostjan
- Department of Surgery, Division of General Surgery, Medical University of Vienna, Vienna, Austria
| | - Thomas Gruenberger
- Department of Surgery, Division of General Surgery, Medical University of Vienna, Vienna, Austria
| | - Takashi Kumada
- Department of Gastroenterology, Ogaki Municipal Hospital, Ogaki, Japan
| | - Hidenori Toyoda
- Department of Gastroenterology, Ogaki Municipal Hospital, Ogaki, Japan
| | - Toshifumi Tada
- Department of Gastroenterology, Ogaki Municipal Hospital, Ogaki, Japan
| | - Thomas S. Weiss
- Center for Liver Cell Research, Children's University Hospital (KUNO), University of Regensburg Hospital, Regensburg, Germany
| | - Michael Trauner
- Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Mikulits
- Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Center Vienna, Medical University of Vienna, Vienna, Austria
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Wetzel S, Seipold L, Saftig P. The metalloproteinase ADAM10: A useful therapeutic target? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017. [PMID: 28624438 DOI: 10.1016/j.bbamcr.2017.06.005] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Proteolytic cleavage represents a unique and irreversible posttranslational event regulating the function and half-life of many intracellular and extracellular proteins. The metalloproteinase ADAM10 has raised attention since it cleaves an increasing number of protein substrates close to the extracellular membrane leaflet. This "ectodomain shedding" regulates the turnover of a number of transmembrane proteins involved in cell adhesion and receptor signaling. It can initiate intramembrane proteolysis followed by nuclear transport and signaling of the cytoplasmic domain. ADAM10 has also been implicated in human disorders ranging from neurodegeneration to dysfunction of the immune system and cancer. Targeting proteases for therapeutic purposes remains a challenge since these enzymes including ADAM10 have a wide range of substrates. Accelerating or inhibiting a specific protease activity is in most cases associated with unwanted side effects and a therapeutic useful window of application has to be carefully defined. A better understanding of the regulatory mechanisms controlling the expression, subcellular localization and activity of ADAM10 will likely uncover suitable drug targets which will allow a more specific and fine-tuned modulation of its proteolytic activity.
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Affiliation(s)
- Sebastian Wetzel
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany
| | - Lisa Seipold
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany
| | - Paul Saftig
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany.
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Dengler M, Huber H, Müller CJ, Zellmer A, Rauch P, Mikulits W. Accurate Determination of Soluble Axl by Enzyme-Linked Immunosorbent Assay. Assay Drug Dev Technol 2016; 14:543-550. [PMID: 27805424 DOI: 10.1089/adt.2016.743] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Levels of soluble Axl (sAxl) are routinely assessed in human sera by sandwich enzyme-linked immunosorbent assay (ELISA). Although sAxl values are suggested to diagnose different types of disorders, no uniform ELISA method is available, allowing the reliable interassay comparison between results. Furthermore, little is known about the stability of sAxl under storage conditions, which is a relevant parameter for biomedical trials. The evaluation of sAxl stability under various stress conditions and the determination of proper conditions to use the sAxl ELISA for routine clinical applications are of great interest. In this study, serum samples were subjected to freeze-thaw cycles and incubation at different temperatures to analyze the stability of sAxl by ELISA. Dilution and spike-in experiments were carried out to examine the impact of serum and diluent components on the ELISA performance. Various diluents and media were employed to resolve masking effects of the serum. The assay components were further optimized for long-term usability by treatment with stabilizers and validation under temperature stress. Indeed, sAxl showed long-term stability in serum during freeze-thaw cycles and incubation under temperature stress conditions. The dilution experiments revealed that unknown components in the serum caused masking effects that can be reduced by proper dilutions. The assay performance was further increased by using a standardized buffer system to dilute serum samples. Stabilization of coated plates and of streptavidin-horseradish peroxidase allowed long-term storage for up to 6 months. In sum, our data demonstrate proper ELISA conditions, allowing the accurate analysis of sAxl levels in human serum.
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Affiliation(s)
- Mirko Dengler
- 1 Department of Medicine I, Division: Institute of Cancer Research, Comprehensive Cancer Center Vienna, Medical University of Vienna , Vienna, Austria
| | - Heidemarie Huber
- 1 Department of Medicine I, Division: Institute of Cancer Research, Comprehensive Cancer Center Vienna, Medical University of Vienna , Vienna, Austria
| | - Christian J Müller
- 2 Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna , Vienna, Austria
| | | | - Peter Rauch
- 3 Candor Bioscience GmbH , Wangen im Allgäu, Germany
| | - Wolfgang Mikulits
- 1 Department of Medicine I, Division: Institute of Cancer Research, Comprehensive Cancer Center Vienna, Medical University of Vienna , Vienna, Austria
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The Role of TAM Family Receptors in Immune Cell Function: Implications for Cancer Therapy. Cancers (Basel) 2016; 8:cancers8100097. [PMID: 27775650 PMCID: PMC5082387 DOI: 10.3390/cancers8100097] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 10/13/2016] [Accepted: 10/14/2016] [Indexed: 01/30/2023] Open
Abstract
The TAM receptor protein tyrosine kinases-Tyro3, Axl, and Mer-are essential regulators of immune homeostasis. Guided by their cognate ligands Growth arrest-specific gene 6 (Gas6) and Protein S (Pros1), these receptors ensure the resolution of inflammation by dampening the activation of innate cells as well as by restoring tissue function through promotion of tissue repair and clearance of apoptotic cells. Their central role as negative immune regulators is highlighted by the fact that deregulation of TAM signaling has been linked to the pathogenesis of autoimmune, inflammatory, and infectious diseases. Importantly, TAM receptors have also been associated with cancer development and progression. In a cancer setting, TAM receptors have a dual regulatory role, controlling the initiation and progression of tumor development and, at the same time, the associated anti-tumor responses of diverse immune cells. Thus, modulation of TAM receptors has emerged as a potential novel strategy for cancer treatment. In this review, we discuss our current understanding of how TAM receptors control immunity, with a particular focus on the regulation of anti-tumor responses and its implications for cancer immunotherapy.
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14
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Zhen Y, Priest SO, Shao WH. Opposing Roles of Tyrosine Kinase Receptors Mer and Axl Determine Clinical Outcomes in Experimental Immune-Mediated Nephritis. THE JOURNAL OF IMMUNOLOGY 2016; 197:2187-94. [PMID: 27527599 DOI: 10.4049/jimmunol.1600793] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/18/2016] [Indexed: 12/16/2022]
Abstract
Glomerulonephritis is one of the most severe manifestations of systemic lupus erythematosus, with considerable morbidity and mortality. There remains a major unmet need for successful management of lupus nephritis. TAM family receptor tyrosine kinases (Mer and Axl) play an important role in the maintenance of immune homeostasis in the kidney. Mer is constitutively expressed in the glomeruli; Axl expression is inducible in glomeruli under inflammatory conditions. To investigate the distinct functions of Axl and Mer in lupus nephritis, we compared the severity of nephrotoxic serum glomerulonephritis in wild-type (WT), Axl-knockout (KO), Mer-KO, and Axl/Mer-KO mice. Mer-KO mice developed severe glomerulonephritis, with significantly decreased survival and increased blood urea nitrogen levels compared with WT mice given the same treatment. However, nephrotoxic serum-treated Axl-KO mice had significantly increased survival rates and improved renal function compared with similarly treated WT, Mer-KO, and Axl/Mer-KO mice. Interestingly, mice lacking both Axl and Mer developed kidney inflammation comparable to WT mice. Western blot analysis revealed significantly increased Stat3 phosphorylation and caspase-1 activation in the kidneys of nephritic Mer-KO mice. In contrast, Axl-deficient nephrotoxic serum-injected mice showed decreased Akt phosphorylation and Bcl-xL upregulation. Thus, the reciprocal activation of Axl and Mer receptor tyrosine kinases has a major impact on the outcome of renal inflammation.
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Affiliation(s)
- Yuxuan Zhen
- Section of Rheumatology, Department of Medicine, Temple University, Philadelphia, PA 19140
| | - Stephen O Priest
- Section of Rheumatology, Department of Medicine, Temple University, Philadelphia, PA 19140
| | - Wen-Hai Shao
- Section of Rheumatology, Department of Medicine, Temple University, Philadelphia, PA 19140
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15
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Orme JJ, Du Y, Vanarsa K, Mayeux J, Li L, Mutwally A, Arriens C, Min S, Hutcheson J, Davis LS, Chong BF, Satterthwaite AB, Wu T, Mohan C. Heightened cleavage of Axl receptor tyrosine kinase by ADAM metalloproteases may contribute to disease pathogenesis in SLE. Clin Immunol 2016; 169:58-68. [PMID: 27237127 PMCID: PMC5193537 DOI: 10.1016/j.clim.2016.05.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 12/26/2022]
Abstract
Systemic lupus erythematosus (SLE) is characterized by antibody-mediated chronic inflammation in the kidney, lung, skin, and other organs to cause inflammation and damage. Several inflammatory pathways are dysregulated in SLE, and understanding these pathways may improve diagnosis and treatment. In one such pathway, Axl tyrosine kinase receptor responds to Gas6 ligand to block inflammation in leukocytes. A soluble form of the Axl receptor ectodomain (sAxl) is elevated in serum from patients with SLE and lupus-prone mice. We hypothesized that sAxl in SLE serum originates from the surface of leukocytes and that the loss of leukocyte Axl contributes to the disease. We determined that macrophages and B cells are a source of sAxl in SLE and in lupus-prone mice. Shedding of the Axl ectodomain from the leukocytes of lupus-prone mice is mediated by the matrix metalloproteases ADAM10 and TACE (ADAM17). Loss of Axl from lupus-prone macrophages renders them unresponsive to Gas6-induced anti-inflammatory signaling in vitro. This phenotype is rescued by combined ADAM10/TACE inhibition. Mice with Axl-deficient macrophages develop worse disease than controls when challenged with anti-glomerular basement membrane (anti-GBM) sera in an induced model of nephritis. ADAM10 and TACE also mediate human SLE PBMC Axl cleavage. Collectively, these studies indicate that increased metalloprotease-mediated cleavage of leukocyte Axl may contribute to end organ disease in lupus. They further suggest dual ADAM10/TACE inhibition as a potential therapeutic modality in SLE.
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Affiliation(s)
- Jacob J Orme
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Yong Du
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States; The Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, United States
| | - Kamala Vanarsa
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States; The Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, United States
| | - Jessica Mayeux
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Li Li
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Azza Mutwally
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Cristina Arriens
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Soyoun Min
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Jack Hutcheson
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Laurie S Davis
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Benjamin F Chong
- The Department of Dermatology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Anne B Satterthwaite
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Tianfu Wu
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States; The Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, United States
| | - Chandra Mohan
- The Department of Internal Medicine, Rheumatic Diseases Division, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States; The Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, United States.
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16
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Mok CC, Ding HH, Kharboutli M, Mohan C. Axl, Ferritin, Insulin-Like Growth Factor Binding Protein 2, and Tumor Necrosis Factor Receptor Type II as Biomarkers in Systemic Lupus Erythematosus. Arthritis Care Res (Hoboken) 2016; 68:1303-9. [PMID: 26749069 DOI: 10.1002/acr.22835] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Revised: 12/14/2015] [Accepted: 01/05/2016] [Indexed: 12/21/2022]
Abstract
OBJECTIVE To evaluate the performance of 4 serum protein markers for detecting concurrent clinical activity in patients with systemic lupus erythematosus (SLE). METHODS Consecutive patients who fulfilled ≥4 American College of Rheumatology classification criteria for SLE and healthy controls were recruited for serologic testing of 4 protein markers identified by antibody-coated microarray screen, namely Axl, ferritin, insulin-like growth factor binding protein 2 (IGFBP-2), and tumor necrosis factor receptor type II (TNFRII). SLE disease activity was assessed by the Safety of Estrogens in Lupus Erythematosus National Assessment version of the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and physician's global assessment (PGA). Levels of these markers were correlated with SLEDAI scores, and their sensitivity and specificity for clinical SLE activity were determined. RESULTS A total of 94 SLE patients (98% women, mean ± SD age 28.7 ± 9.4 years, mean ± SD disease duration 5.4 ± 5.0 years) and 49 healthy controls were studied. Fifty-two patients had clinically active SLE (defined as SLEDAI score ≥6 or having a flare). The serum concentrations of Axl, ferritin, IGFBP-2, and TNFRII were significantly higher in patients with active SLE than in those with inactive SLE or in controls. The levels of these markers correlated strongly and significantly with anti-double stranded DNA (anti-dsDNA), C3, and clinical SLEDAI and PGA scores. These markers were more specific, but less sensitive, in detecting concurrent SLE activity than elevated anti-dsDNA or depressed C3. Levels of Axl, TNFRII, and IGFBP-2, but not ferritin, could differentiate active renal from active nonrenal or inactive SLE. The specificity of Axl and IGFBP-2 for concurrent active lupus nephritis was higher than anti-dsDNA or C3. CONCLUSION Serum proteomic markers are potentially useful for diagnosing SLE and monitoring disease activity. The performance of Axl and IGFBP-2 in lupus nephritis should be further explored in a longitudinal cohort of SLE patients.
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Several Critical Cell Types, Tissues, and Pathways Are Implicated in Genome-Wide Association Studies for Systemic Lupus Erythematosus. G3-GENES GENOMES GENETICS 2016; 6:1503-11. [PMID: 27172182 PMCID: PMC4889647 DOI: 10.1534/g3.116.027326] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We aimed to elucidate the cell types, tissues, and pathways influenced by common variants in systemic lupus erythematosus (SLE). We applied a nonparameter enrichment statistical approach, termed SNPsea, in 181 single nucleotide polymorphisms (SNPs) that have been identified to be associated with the risk of SLE through genome-wide association studies (GWAS) in Eastern Asian and Caucasian populations, to manipulate the critical cell types, tissues, and pathways. In the two most significant cells’ findings (B lymphocytes and CD14+ monocytes), we subjected the GWAS association evidence in the Han Chinese population to an enrichment test of expression quantitative trait locus (QTL) sites and DNase I hypersensitivity, respectively. In both Eastern Asian and Caucasian populations, we observed that the expression level of SLE GWAS implicated genes was significantly elevated in xeroderma pigentosum B cells (P ≤ 1.00 × 10−6), CD14+ monocytes (P ≤ 2.74 × 10−4) and CD19+ B cells (P ≤ 2.00 × 10−6), and plasmacytoid dendritic cells (pDCs) (P ≤ 9.00 × 10−6). We revealed that the SLE GWAS-associated variants were more likely to reside in expression QTL in B lymphocytes (q1/q0 = 2.15, P = 1.23 × 10−44) and DNase I hypersensitivity sites (DHSs) in CD14+ monocytes (q1/q0 = 1.41, P = 0.08). We observed the common variants affected the risk of SLE mostly through by regulating multiple immune system processes and immune response signaling. This study sheds light on several immune cells and responses, as well as the regulatory effect of common variants in the pathogenesis of SLE.
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18
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Analysis of receptor tyrosine kinase genetics identifies two novel risk loci in GAS6 and PROS1 in Behçet's disease. Sci Rep 2016; 6:26662. [PMID: 27222359 PMCID: PMC4879572 DOI: 10.1038/srep26662] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 04/29/2016] [Indexed: 12/23/2022] Open
Abstract
The TAM kinase (Tyro3, Axl, Mer) and its two ligands (Gas6 and protein S) have been shown to play an important regulatory role in the innate immune response. The present study aimed to investigate whether the tag single-nucleotide polymorphisms (tag SNPs) of these 5 protein-coding genes are associated with Behçet’s disease (BD). A two-stage association study was performed in a total of 907 BD patients and 1780 healthy controls. Altogether 32 polymorphisms were tested, using a Sequenom MassARRAY genotyping method in the first stage and a PCR-restriction fragment length polymorphism (PCR-RFLP) assay in the replication phase. Real-time PCR was performed to test the relative mRNA expression level of GAS6 and PROS1 from different SNP genotyped healthy individuals. The frequency of the C allele and CC genotype of rs9577873 in GAS6 (Pc = 4.92 × 10−5, Pc = 1.91 × 10−5, respectively) and A allele and AA genotype of rs4857037 in PROS1 (Pc = 1.85 × 10−6, Pc = 4.52 × 10−7, respectively) were significantly increased in BD. GAS6 expression in CC carriers of rs9577873 was significantly lower than that in CT/TT individuals (P = 0.001). Decreased expression of GAS6 and increased pro-inflammatory cytokines (IL-6 and IFN-γ: P = 4.23 × 10−4, P = 0.011, respectively) in individuals carrying the CC genotype suggest that the TAM-GAS6/PROS1 signal pathway may be involved in the pathogenesis of BD.
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19
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Axl and Mer Receptor Tyrosine Kinases: Distinct and Nonoverlapping Roles in Inflammation and Cancer? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 930:113-32. [PMID: 27558819 DOI: 10.1007/978-3-319-39406-0_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The receptor tyrosine kinases Axl and Mer subserve the process of termination of proinflammatory signaling and have key roles in both the resolution of inflammation and restoration of homeostasis. Axl functions prominently under conditions of tissue stress or in response to infection, whereas Mer has a major role in maintenance of homeostasis within tissues. Distinct patterns of expression of Axl and Mer underlie their clearly defined functional roles during the initiation and progression of inflammation. Axl and Mer are expressed by tumor cells and by infiltrating inflammatory cells and the regulation of cellular function via Axl and Mer signaling is also important for tumorigenesis, tumor progression, and metastasis. In this review, we consider the divergent functions of Axl and Mer in the context of inflammatory processes within tumors and the implications for development of therapeutic agents targeting these receptors.
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20
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Jung JY, Suh CH. Incomplete clearance of apoptotic cells in systemic lupus erythematosus: pathogenic role and potential biomarker. Int J Rheum Dis 2015; 18:294-303. [PMID: 25884792 DOI: 10.1111/1756-185x.12568] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with repeated inflammation against multiple organs. Although its pathophysiology is not yet unveiled, uncleared apoptotic cells and their accumulation in tissue contribute to the autoimmune disturbance in SLE. Apoptosis is a programmed cell death process, which maintains tissue homeostasis and inhibits the development of any further immune response against apoptotic remnants. Earlier studies revealed that various 'eat-me' signals on apoptotic cells, bridging molecules and their receptors on phagocytes play a role in such a complicated process. Tyro3-Axl-Mer receptors, their bridging molecules, milk fat globulin epidermal growth factor-8, T-cell immunoglobulin mucin domain protein family, scavenger receptors, C1q, and pentraxins were found to be abnormal in SLE. In this review, apoptosis and clearance of its remnants are summarized, and the molecules involved in the incomplete clearance of apoptotic cells in SLE are discussed.
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Affiliation(s)
- Ju-Yang Jung
- Department of Rheumatology, Ajou University School of Medicine, Suwon, Korea
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21
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Targeted GAS6 delivery to the CNS protects axons from damage during experimental autoimmune encephalomyelitis. J Neurosci 2015; 34:16320-35. [PMID: 25471571 DOI: 10.1523/jneurosci.2449-14.2014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Growth arrest-specific protein 6 (GAS6) is a soluble agonist of the TYRO3, AXL, MERTK (TAM) family of receptor tyrosine kinases identified to have anti-inflammatory, neuroprotective, and promyelinating properties. During experimental autoimmune encephalomyelitis (EAE), wild-type (WT) mice demonstrate a significant induction of Gas6, Axl, and Mertk but not Pros1 or Tyro3 mRNA. We tested the hypothesis that intracerebroventricular delivery of GAS6 directly into the CNS of WT mice during myelin oligodendrocyte glycoprotein (MOG)-induced EAE would improve the clinical course of disease relative to artificial CSF (ACSF)-treated mice. GAS6 did not delay disease onset, but significantly reduced the clinical scores during peak and chronic EAE. Mice receiving GAS6 for 28 d had preserved SMI31(+) neurofilament immunoreactivity, significantly fewer SMI32(+) axonal swellings and spheroids and less demyelination relative to ACSF-treated mice. Alternate-day subcutaneous IFNβ injection did not enhance GAS6 treatment effectiveness. Gas6(-/-) mice sensitized with MOG35-55 peptide exhibit higher clinical scores during late peak to early chronic disease, with significantly increased SMI32(+) axonal swellings and Iba1(+) microglia/macrophages, enhanced expression of several proinflammatory mRNA molecules, and decreased expression of early oligodendrocyte maturation markers relative to WT mouse spinal cords with scores for 8 consecutive days. During acute EAE, flow cytometry showed significantly more macrophages but not T-cell infiltrates in Gas6(-/-) spinal cords than WT spinal cords. Our data are consistent with GAS6 being protective during EAE by dampening the inflammatory response, thereby preserving axonal integrity and myelination.
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22
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Lew ED, Oh J, Burrola PG, Lax I, Zagórska A, Través PG, Schlessinger J, Lemke G. Differential TAM receptor-ligand-phospholipid interactions delimit differential TAM bioactivities. eLife 2014; 3. [PMID: 25265470 PMCID: PMC4206827 DOI: 10.7554/elife.03385] [Citation(s) in RCA: 193] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 09/28/2014] [Indexed: 12/22/2022] Open
Abstract
The TAM receptor tyrosine kinases Tyro3, Axl, and Mer regulate key features of cellular physiology, yet the differential activities of the TAM ligands Gas6 and Protein S are poorly understood. We have used biochemical and genetic analyses to delineate the rules for TAM receptor–ligand engagement and find that the TAMs segregate into two groups based on ligand specificity, regulation by phosphatidylserine, and function. Tyro3 and Mer are activated by both ligands but only Gas6 activates Axl. Optimal TAM signaling requires coincident TAM ligand engagement of both its receptor and the phospholipid phosphatidylserine (PtdSer): Gas6 lacking its PtdSer-binding ‘Gla domain’ is significantly weakened as a Tyro3/Mer agonist and is inert as an Axl agonist, even though it binds to Axl with wild-type affinity. In two settings of TAM-dependent homeostatic phagocytosis, Mer plays a predominant role while Axl is dispensable, and activation of Mer by Protein S is sufficient to drive phagocytosis. DOI:http://dx.doi.org/10.7554/eLife.03385.001 Cells send out and receive signals to communicate with other cells. Detecting these signals is largely carried out by proteins called receptors that span the cell surface membrane. These proteins typically have extracellular domains outside of the cell that can bind to specific signaling molecules and an intracellular domain inside the cell that relays the information inwards to trigger a response. Three such receptor proteins are collectively known as the TAM receptors. Each day, many billions of cells in the human body die and are engulfed by other cells and broken down so that their building blocks can be reused. TAM receptors are required for this process; and the TAM receptors also help prevent the immune system from going out of control, which would damage the body's own tissues. Two different signaling proteins, called Gas6 and Protein S, can bind to and activate TAM receptors. Both of the signaling proteins can also bind to a phospholipid molecule that is found on the surface membrane of dead cells. However, it is not known if all three TAM receptors bind to both signaling proteins equally, and the importance of the phospholipid-binding domain in the signaling proteins remains unclear. To shed light on the workings of these receptors, Lew et al. created mouse cells that each only express one out of the three TAM receptors. These cells were then exposed to intact Gas6 and Protein S, or shortened versions that lacked the phospholipid-binding domain. Lew et al. found that Gas6 could trigger a response through all three TAM receptors but that Protein S was specific for only two out of the three receptors. Signaling proteins with or without their phospholipid-binding domains bound equally well to the receptors, but the maximum level of response was only triggered when both signaling proteins were intact and the phospholipid molecule was present. This is important since the phospholipid can be thought of as an ‘eat-me’ signal by which the dead cells are recognized by the TAM receptor-expressing cells that will engulf them. Using mice that only produce a TAM receptor called Mer, Lew et al. show that Protein S alone can trigger the process that engulfs and breaks down cells in a living organism. These data and previous work suggest that two TAM receptors—including Mer—are involved in the daily engulfment of dying cells, whereas the third mediates this process during infection and tissue damage. Molecules that inhibit or activate the function of TAM receptors are currently being developed to treat cancer and other diseases. By revealing which receptors respond to which signaling molecules, the findings of Lew et al. will serve to guide these efforts. DOI:http://dx.doi.org/10.7554/eLife.03385.002
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Affiliation(s)
- Erin D Lew
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Jennifer Oh
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Patrick G Burrola
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Irit Lax
- Department of Pharmacology, Yale University School of Medicine, New Haven, United States
| | - Anna Zagórska
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Paqui G Través
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Joseph Schlessinger
- Department of Pharmacology, Yale University School of Medicine, New Haven, United States
| | - Greg Lemke
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
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23
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Zagórska A, Través PG, Lew ED, Dransfield I, Lemke G. Diversification of TAM receptor tyrosine kinase function. Nat Immunol 2014; 15:920-8. [PMID: 25194421 PMCID: PMC4169336 DOI: 10.1038/ni.2986] [Citation(s) in RCA: 293] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 08/05/2014] [Indexed: 12/12/2022]
Abstract
The clearance of apoptotic cells is critical for both tissue homeostasis and the resolution of inflammation. We found that the TAM receptor tyrosine kinases Axl and Mer had distinct roles as phagocytic receptors in these two settings, in which they exhibited divergent expression, regulation and activity. Mer acted as a tolerogenic receptor in resting macrophages and during immunosuppression. In contrast, Axl was an inflammatory response receptor whose expression was induced by proinflammatory stimuli. Axl and Mer differed in their ligand specificities, ligand-receptor complex formation in tissues, and receptor shedding upon activation. These differences notwithstanding, phagocytosis by either protein was strictly dependent on receptor activation triggered by bridging of TAM receptor-ligand complexes to the 'eat-me' signal phosphatidylserine on the surface of apoptotic cells.
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Affiliation(s)
- Anna Zagórska
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA
| | - Paqui G Través
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA
| | - Erin D Lew
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA
| | - Ian Dransfield
- MRC Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK
| | - Greg Lemke
- 1] Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA. [2] Immunobiology and Microbial Pathogenesis Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA
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24
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Abstract
Innate immune detection and subsequent immune responses rely on the initial recognition of pathogen specific molecular motifs. Foreign nucleic acids are key structures recognised by the immune system, recognition of which occurs mainly through the use of nucleic acid receptors including members of the Toll-like receptors, AIM2-like receptors, RIG-I-like receptors and intracellular DNA receptors. While the immune system is critically important in protecting the host from infection, it is of utmost importance that it is tightly regulated, in order to prevent recognition of self-nucleic acids and the subsequent development of autoimmunity. Defects in the mechanisms regulating such pathways, for example mutations in endonucleases that clear DNA, altered expression of nucleic acid sensors and defects in negative regulators of these signalling pathways involved in RNA/DNA sensing, have all been implicated in promoting the generation of autoimmune responses. This evidence, as reviewed here, suggests that novel therapeutics targeting these sensors and their downstream pathways may be of use in the treatment of patients with autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis and primary Sjögren's syndrome.
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Affiliation(s)
- Siobhán Smith
- Molecular and Cellular Therapeutics and RCSI Research Institute, Royal College of Surgeons in Ireland, 123 St. Stephens Green, Dublin 2, Ireland
| | - Caroline Jefferies
- Molecular and Cellular Therapeutics and RCSI Research Institute, Royal College of Surgeons in Ireland, 123 St. Stephens Green, Dublin 2, Ireland.
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