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Oleic acid triggers metabolic rewiring of T cells poising them for T helper 9 differentiation. iScience 2024; 27:109496. [PMID: 38558932 PMCID: PMC10981094 DOI: 10.1016/j.isci.2024.109496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/29/2023] [Accepted: 03/09/2024] [Indexed: 04/04/2024] Open
Abstract
T cells are the most common immune cells in atherosclerotic plaques, and the function of T cells can be altered by fatty acids. Here, we show that pre-exposure of CD4+ T cells to oleic acid, an abundant fatty acid linked to cardiovascular events, upregulates core metabolic pathways and promotes differentiation into interleukin-9 (IL-9)-producing cells upon activation. RNA sequencing of non-activated T cells reveals that oleic acid upregulates genes encoding key enzymes responsible for cholesterol and fatty acid biosynthesis. Transcription footprint analysis links these expression changes to the differentiation toward TH9 cells, a pro-atherogenic subset. Spectral flow cytometry shows that pre-exposure to oleic acid results in a skew toward IL-9+-producing T cells upon activation. Importantly, pharmacological inhibition of either cholesterol or fatty acid biosynthesis abolishes this effect, suggesting a beneficial role for statins beyond cholesterol lowering. Taken together, oleic acid may affect inflammatory diseases like atherosclerosis by rewiring T cell metabolism.
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Autoreactive B cells in rheumatoid arthritis include mainly activated CXCR3+ memory B cells and plasmablasts. JCI Insight 2023; 8:e172006. [PMID: 37725442 PMCID: PMC10619489 DOI: 10.1172/jci.insight.172006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 09/06/2023] [Indexed: 09/21/2023] Open
Abstract
Many autoimmune diseases (AIDs) are characterized by the persistence of autoreactive B cell responses, which have been directly implicated in disease pathogenesis. How and why these cells are generated or how they are maintained for years is largely unknown. Rheumatoid arthritis (RA) is among the most common AIDs and is characterized by autoantibodies recognizing proteins with posttranslational modifications (PTMs). This PTM-directed autoreactive B cell compartment is ill defined. Here, we visualized the B cell response against the three main types of PTM antigens implicated in RA by spectral flow cytometry. Our results showed extensive cross-reactivity of PTM-directed B cells against all three PTM antigens (citrulline, homocitrulline, and acetyllysine). Unsupervised clustering revealed several distinct memory B cell (mBC) populations. PTM-directed cells clustered with the most recently activated class-switched mBC phenotype, with high CD80, low CD24, and low CD21 expression. Notably, patients also harbored large fractions of PTM-directed plasmablasts (PBs). Both PTM-directed mBCs and PBs showed high expression of CXCR3, a receptor for chemokines present in abundance in arthritic joints. Together, our data provide detailed insight into the biology of B cell autoreactivity and its remarkable, seemingly exhaustless persistence in a prominent human AID.
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Comparative Photoaffinity Profiling of Omega-3 Signaling Lipid Probes Reveals Prostaglandin Reductase 1 as a Metabolic Hub in Human Macrophages. J Am Chem Soc 2022; 144:18938-18947. [PMID: 36197299 PMCID: PMC9585591 DOI: 10.1021/jacs.2c06827] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
The fish oil constituent
docosahexaenoic acid (DHA, 22:6
n-3) is
a signaling lipid with anti-inflammatory properties. The molecular
mechanisms underlying the biological effect of DHA are poorly understood.
Here, we report the design, synthesis, and application of a complementary
pair of bio-orthogonal, photoreactive probes based on the polyunsaturated
scaffold DHA and its oxidative metabolite 17-hydroxydocosahexaenoic
acid (17-HDHA). In these probes, an alkyne serves as a handle to introduce
a fluorescent reporter group or a biotin-affinity tag via copper(I)-catalyzed
azide-alkyne cycloaddition. This pair of chemical probes was used
to map specific targets of the omega-3 signaling lipids in primary
human macrophages. Prostaglandin reductase 1 (PTGR1) was identified
as an interaction partner that metabolizes 17-oxo-DHA, an oxidative
metabolite of 17-HDHA. 17-oxo-DHA reduced the formation of pro-inflammatory
lipids 5-HETE and LTB4 in human macrophages and neutrophils. Our results
demonstrate the potential of comparative photoaffinity protein profiling
for the discovery of metabolic enzymes of bioactive lipids and highlight
the power of chemical proteomics to uncover new biological insights.
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Surface Ig variable domain glycosylation affects autoantigen binding and acts as threshold for human autoreactive B cell activation. SCIENCE ADVANCES 2022; 8:eabm1759. [PMID: 35138894 PMCID: PMC8827743 DOI: 10.1126/sciadv.abm1759] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 12/15/2021] [Indexed: 05/05/2023]
Abstract
The hallmark autoantibodies in rheumatoid arthritis are characterized by variable domain glycans (VDGs). Their abundant occurrence results from the selective introduction of N-linked glycosylation sites during somatic hypermutation, and their presence is predictive for disease development. However, the functional consequences of VDGs on autoreactive B cells remain elusive. Combining crystallography, glycobiology, and functional B cell assays allowed us to dissect key characteristics of VDGs on human B cell biology. Crystal structures showed that VDGs are positioned in the vicinity of the antigen-binding pocket, and dynamic modeling combined with binding assays elucidated their impact on binding. We found that VDG-expressing B cell receptors stay longer on the B cell surface and that VDGs enhance B cell activation. These results provide a rationale on how the acquisition of VDGs might contribute to the breach of tolerance of autoreactive B cells in a major human autoimmune disease.
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Immunoprofiling of early, untreated rheumatoid arthritis using mass cytometry reveals an activated basophil subset inversely linked to ACPA status. Arthritis Res Ther 2021; 23:272. [PMID: 34715910 PMCID: PMC8555233 DOI: 10.1186/s13075-021-02630-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 09/19/2021] [Indexed: 11/24/2022] Open
Abstract
Background Autoantibody production is a hallmark of rheumatoid arthritis (RA). Anti-citrullinated protein antibodies (ACPA) are highly disease-specific, and their presence is associated with more severe disease and poor prognosis compared to ACPA-negative patients. However, the immune cell composition associated with antibody-positive/negative disease is incompletely defined. Mass cytometry (MC) is a high-dimensional technique offering new possibilities in the determination of the immune cell composition in rheumatic diseases. Here, we set up a broad phenotyping panel to study the immune cell profile of early untreated RA to investigate if specific immune cell subsets are associated with ACPA+ versus ACPA− RA. Methods Freshly obtained PBMCs of early, untreated RA patients (8 ACPA+ and 7 ACPA−) were analysed using a 36-marker MC panel, including markers related to various immune lineages. Data were processed using Cytosplore for dimensional reduction (HSNE) and clustering. Groups were compared using Cytofast. A second validation cohort of cryopreserved PBMCs obtained from early RA patients (27 ACPA+ and 20 ACPA−) was used to confirm MC data by flow cytometry (FC). FC data were processed and analysed using both an unsupervised analysis pipeline and through manual gating. Results MC indicated no differences when comparing major immune lineages (i.e. monocytes, T and B cells), but highlighted two innate subsets: CD62L+ basophils (p = 0.33) and a subset of CD16− NK cells (p = 0.063). Although the NK cell subset did not replicate by FC, FC replication confirmed the difference in CD62L+ basophil frequency when comparing ACPA+ to ACPA− patients (mean 0.32% vs. 0.13%; p = 0.01). Conclusions Although no differences in major lineages were found between early ACPA+ and ACPA− RA, this study identified the reduced presence of activated basophils in ACPA-negative disease as compared to ACPA-positive disease and thereby provides the first evidence for a connection between activated basophils and ACPA status. Supplementary Information The online version contains supplementary material available at 10.1186/s13075-021-02630-8.
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Mass-spectrometric identification of carbamylated proteins present in the joints of rheumatoid arthritis patients and controls. Clin Exp Rheumatol 2021. [DOI: 10.55563/clinexprheumatol/0ms5pk] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Anti-Inflammatory and Proresolving Effects of the Omega-6 Polyunsaturated Fatty Acid Adrenic Acid. THE JOURNAL OF IMMUNOLOGY 2020; 205:2840-2849. [PMID: 33008950 DOI: 10.4049/jimmunol.1801653] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 09/07/2020] [Indexed: 12/31/2022]
Abstract
Polyunsaturated fatty acids (PUFAs) and their metabolites are potent regulators of inflammation. Generally, omega (n)-3 PUFAs are considered proresolving whereas n-6 PUFAs are classified as proinflammatory. In this study, we characterized the inflammatory response in murine peritonitis and unexpectedly found the accumulation of adrenic acid (AdA), a poorly studied n-6 PUFA. Functional studies revealed that AdA potently inhibited the formation of the chemoattractant leukotriene B4 (LTB4), specifically in human neutrophils, and this correlated with a reduction of its precursor arachidonic acid (AA) in free form. AdA exposure in human monocyte-derived macrophages enhanced efferocytosis of apoptotic human neutrophils. In vivo, AdA treatment significantly alleviated arthritis in an LTB4-dependent murine arthritis model. Our findings are, to our knowledge, the first to indicate that the n-6 fatty acid AdA effectively blocks production of LTB4 by neutrophils and could play a role in resolution of inflammation in vivo.
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Complement component C1q is produced by isolated articular chondrocytes. Osteoarthritis Cartilage 2020; 28:675-684. [PMID: 31634584 DOI: 10.1016/j.joca.2019.09.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 09/10/2019] [Accepted: 09/21/2019] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Inflammation and innate immune responses may contribute to development and progression of Osteoarthritis (OA). Chondrocytes are the sole cell type of the articular cartilage and produce extracellular-matrix molecules. How inflammatory mediators reach chondrocytes is incompletely understood. Previous studies have shown that chondrocytes express mRNA encoding complement proteins such as C1q, suggesting local protein production, which has not been demonstrated conclusively. The aim of this study is to explore C1q production at the protein level by chondrocytes. DESIGN We analysed protein expression of C1q in freshly isolated and cultured human articular chondrocytes using Western blot, ELISA and flow cytometry. We examined changes in mRNA expression of collagen, MMP-1 and various complement genes upon stimulation with pro-inflammatory cytokines or C1q. mRNA expression of C1 genes was determined in articular mouse chondrocytes. RESULTS Primary human articular chondrocytes express genes encoding C1q, C1QA, C1QB, C1QC, and secrete C1q to the extracellular medium. Stimulation of chondrocytes with pro-inflammatory cytokines upregulated C1QA, C1QB, C1QC mRNA expression, although this was not confirmed at the protein level. Extracellular C1q bound to the chondrocyte surface dose dependently. In a pilot study, binding of C1q to chondrocytes resulted in changes in the expression of collagens with a decrease in collagen type 2 and an increase in type 10. Mouse articular chondrocytes also expressed C1QA, C1QB, C1QC, C1R and C1S at the mRNA level. CONCLUSIONS C1q protein can be expressed and secreted by human articular chondrocytes and is able to bind to chondrocytes influencing the relative collagen expression.
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Antibodies and B cells recognising citrullinated proteins display a broad cross-reactivity towards other post-translational modifications. Ann Rheum Dis 2020; 79:472-480. [PMID: 32041746 DOI: 10.1136/annrheumdis-2019-216499] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/17/2020] [Indexed: 11/04/2022]
Abstract
OBJECTIVE Autoantibodies against antigens carrying distinct post-translational modifications (PTMs), such as citrulline, homocitrulline or acetyllysine, are hallmarks of rheumatoid arthritis (RA). The relation between these anti-modified protein antibody (AMPA)-classes is poorly understood as is the ability of different PTM-antigens to activate B-cell receptors (BCRs) directed against citrullinated proteins (CP). Insights into the nature of PTMs able to activate such B cells are pivotal to understand the 'evolution' of the autoimmune response conceivable underlying the disease. Here, we investigated the cross-reactivity of monoclonal AMPA and the ability of different types of PTM-antigens to activate CP-reactive BCRs. METHODS BCR sequences from B cells isolated using citrullinated or acetylated antigens were used to produce monoclonal antibodies (mAb) followed by a detailed analysis of their cross-reactivity towards PTM-antigens. Ramos B-cell transfectants expressing CP-reactive IgG BCRs were generated and their activation on stimulation with PTM-antigens investigated. RESULTS Most mAbs were highly cross-reactive towards multiple PTMs, while no reactivity was observed to the unmodified controls. B cells carrying CP-reactive BCRs showed activation on stimulation with various types of PTM-antigens. CONCLUSIONS Our study illustrates that AMPA exhibit a high cross-reactivity towards at least two PTMs indicating that their recognition pattern is not confined to one type of modification. Furthermore, our data show that CP-reactive B cells are not only activated by citrullinated, but also by carbamylated and/or acetylated antigens. These data are vital for the understanding of the breach of B-cell tolerance against PTM-antigens and the possible contribution of these antigens to RA-pathogenesis.
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Functional and phenotypical analysis of IL-6-secreting CD4 + T cells in human adipose tissue. Eur J Immunol 2018; 48:471-481. [PMID: 29283192 PMCID: PMC5873429 DOI: 10.1002/eji.201747037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 11/27/2017] [Accepted: 12/23/2017] [Indexed: 01/07/2023]
Abstract
Emerging evidence indicates that a dynamic interplay between the immune system and adipocytes contributes to the disturbed homeostasis in adipose tissue of obese subjects. Recently, we observed IL‐6‐secretion by CD4+ T cells from the stromal vascular fraction (SVF) of the infrapatellar fat pad (IFP) of knee osteoarthritis patients directly ex vivo. Here we show that human IL‐6+CD4+ T cells from SVF display a more activated phenotype than the IL‐6− T cells, as evidenced by the expression of the activation marker CD69. Analysis of cytokines secretion, as well as expression of chemokine receptors and transcription factors associated with different Th subsets (Treg, Th1, Th2, Th17 and Tfh) revealed that IL‐6‐secreting CD4+ T cells cannot be assigned to a conventional Th subset. TCRβ gene analysis revealed that IL‐6+ and IL‐6−CD4+ T cells appear clonally unrelated to each other, suggesting a different specificity of these cells. In line with these observations, adipocytes are capable of enhancing IL‐6 production by CD4+ T cells. Thus, IL‐6+CD4+ T cells are TCRαβ T cells expressing an activated phenotype potentially resulting from an interplay with adipocytes that could be involved in the inflammatory processes in the OA joint.
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Lack of high BMI-related features in adipocytes and inflammatory cells in the infrapatellar fat pad (IFP). Arthritis Res Ther 2017; 19:186. [PMID: 28800775 PMCID: PMC5553811 DOI: 10.1186/s13075-017-1395-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 07/24/2017] [Indexed: 01/02/2023] Open
Abstract
Background Obesity is associated with the development and progression of osteoarthritis (OA). Although the infrapatellar fat pad (IFP) could be involved in this association, due to its intracapsular localization in the knee joint, there is currently little known about the effect of obesity on the IFP. Therefore, we investigated cellular and molecular body mass index (BMI)-related features in the IFP of OA patients. Methods Patients with knee OA (N = 155, 68% women, mean age 65 years, mean (SD) BMI 29.9 kg/m2 (5.7)) were recruited: IFP volume was determined by magnetic resonance imaging in 79 patients with knee OA, while IFPs and subcutaneous adipose tissue (SCAT) were obtained from 106 patients undergoing arthroplasty. Crown-like structures (CLS) were determined using immunohistochemical analysis. Adipocyte size was determined by light microscopy and histological analysis. Stromal vascular fraction (SVF) cells were characterized by flow cytometry. Results IFP volume (mean (SD) 23.6 (5.4) mm3) was associated with height, but not with BMI or other obesity-related features. Likewise, volume and size of IFP adipocytes (mean 271 pl, mean 1933 μm) was not correlated with BMI. Few CLS were observed in the IFP, with no differences between overweight/obese and lean individuals. Moreover, high BMI was not associated with higher SVF immune cell numbers in the IFP, nor with changes in their phenotype. No BMI-associated molecular differences were observed, besides an increase in TNFα expression with high BMI. Macrophages in the IFP were mostly pro-inflammatory, producing IL-6 and TNFα, but little IL-10. Interestingly, however, CD206 and CD163 were associated with an anti-inflammatory phenotype, were the most abundantly expressed surface markers on macrophages (81% and 41%, respectively) and CD163+ macrophages had a more activated and pro-inflammatory phenotype than their CD163- counterparts. Conclusions BMI-related features usually observed in SCAT and visceral adipose tissue could not be detected in the IFP of OA patients, a fat depot implicated in OA pathogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s13075-017-1395-9) contains supplementary material, which is available to authorized users.
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Inflammatory features of infrapatellar fat pad in rheumatoid arthritis versus osteoarthritis reveal mostly qualitative differences. Ann Rheum Dis 2017; 77:1088-1090. [PMID: 28780513 DOI: 10.1136/annrheumdis-2017-211673] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/12/2017] [Accepted: 07/18/2017] [Indexed: 02/05/2023]
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Inflammatory Cells in Patients with Endstage Knee Osteoarthritis: A Comparison between the Synovium and the Infrapatellar Fat Pad. J Rheumatol 2016; 43:771-8. [PMID: 26980579 DOI: 10.3899/jrheum.151068] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2016] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To get a better understanding of inflammatory pathways active in the osteoarthritic (OA) joint, we characterized and compared inflammatory cells in the synovium and the infrapatellar fat pad (IFP) of patients with knee OA. METHODS Infiltrating immune cells were characterized by flow cytometry in 76 patients with knee OA (mean age 63.3, 52% women, median body mass index 28.9) from whom synovial tissue (n = 40) and IFP (n = 68) samples were obtained. Pain was assessed by the visual analog scale (VAS; 0-100 mm). Spearman rank correlations and linear regression analyses adjusted for sex and age were performed. RESULTS Macrophages and T cells, followed by mast cells, were the most predominant immune cells in the synovium and IFP, and were equally abundant in these tissues. Macrophages and T cells secreted mostly proinflammatory cytokines even without additional stimulation, indicating their activated state. Accordingly, most CD4+ T cells had a memory phenotype and contained a significant population of cells expressing activation markers (CD25+, CD69+). Interestingly, the percent of CD69+ T cells was higher in synovial than IFP CD4+ T cells. Preliminary analyses indicated that the number of synovial CD4+ T cells were associated with VAS pain (β 0.51, 95% CI 0.09-1.02, p = 0.02). CONCLUSION Our data suggest that the immune cell composition of the synovium and the IFP is similar, and includes activated cells that could contribute to inflammation through secretion of proinflammatory cytokines. Moreover, preliminary analyses indicate that synovial CD4+ T cells might associate with pain in patients with endstage OA of the knee.
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A1.11 T cells in the infrapatellar fat pad of osteoarthritis patients as a source of IL-6 in the joint. Ann Rheum Dis 2015. [DOI: 10.1136/annrheumdis-2015-207259.11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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A6.22 Specialised pro-resolving lipid mediators in chronic inflammation: a comparison between rheumatoid arthritis and osteoarthritis. Ann Rheum Dis 2015. [DOI: 10.1136/annrheumdis-2015-207259.148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Are baseline high molecular weight adiponectin levels associated with radiographic progression in rheumatoid arthritis and osteoarthritis? J Rheumatol 2014; 41:853-7. [PMID: 24692529 DOI: 10.3899/jrheum.130888] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To investigate whether high molecular weight adiponectin (hmwAPN) mediates the associations of total adiponectin (totAPN) with radiographic progression in rheumatoid arthritis (RA) and hand osteoarthritis (HOA). METHODS Associations between baseline hmwAPN or totAPN levels with radiographic progression were determined using multivariate linear regression or generalized estimated equations. RESULTS In patients with RA, totAPN associated positively, whereas in patients with HOA it associated negatively with radiographic progression. In contrast, hmwAPN did not associate significantly with radiographic progression in either cohort. CONCLUSION Our data indicate that the differential effects associated between totAPN and radiographic progression in either RA or HOA are not mediated by hmwAPN.
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Adipocytes modulate the phenotype of human macrophages through secreted lipids. THE JOURNAL OF IMMUNOLOGY 2013; 191:1356-63. [PMID: 23817431 DOI: 10.4049/jimmunol.1203074] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Previous studies have shown accumulation and an enhanced proinflammatory profile of macrophages in adipose tissue of obese mice, indicating the presence of an interaction between adipocytes and macrophages in this tissue. However, the consequences of this interaction in humans are yet incompletely understood. In this study, we explored the modulating effects of adipocytes on the phenotype of macrophages in humans and studied the possible molecular pathways involved. Adipocyte-conditioned media (ACM) treatment of macrophages for 48 h strongly reduced the LPS-induced IL-12p40 secretion by macrophages, whereas the production of TNF-α and other cytokines remained largely unaffected. This effect was independent of the source of adipocytes. Interestingly, the level of inhibition correlated directly with body mass index (BMI) of the adipocyte donor. Because adipocytes release many different cytokines, adipokines, and lipids, we have separated the protein and lipid fractions of ACM, to obtain insight into the molecular nature of the soluble mediators underlying the observed effect. These experiments revealed that the inhibitory effect resided predominantly in the lipid fraction. Further studies revealed that PGE2 and linoleic and oleic acid were potent inhibitors of IL-12p40 secretion. Interestingly, concentrations of these ACM-derived lipids increased with increase in BMI of the adipocyte donor, suggesting that they could mediate the BMI-dependent effects of ACM. To our knowledge, these results provide first evidence that obesity-related changes in adipose tissue macrophage phenotype could be mediated by adipocyte-derived lipids in humans. Intriguingly, these changes appear to be different from those in murine obesity.
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Adipocyte-derived lipids modulate CD4+ T-cell function. Eur J Immunol 2013; 43:1578-87. [PMID: 23504601 DOI: 10.1002/eji.201243096] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 02/08/2013] [Accepted: 03/08/2013] [Indexed: 11/09/2022]
Abstract
Adipose tissue contains several immune cells whose number and phenotype vary depending on the adiposity. In the present study, we show that IFN-γ(+) CD4(+) T cells are enriched in human adipose tissue compared with in blood. To gain insight into the underlying mechanisms, we investigated the possibility that human adipocytes modulate CD4(+) T-cell cytokine production and proliferation and show that CD4(+) T cells produced increased levels of IFN-γ when activated in the presence of adipocytes. This effect was mediated by soluble mediators, as shown in transwell and adipocyte-conditioned medium (ACM) transfer experiments. Additionally, ACM induced increased proliferation of CD4(+) T cells upon activation. Intriguingly, the proliferation-enhancing effect resided mainly in the lipid fraction of ACM, as shown upon separation of the protein and lipid fraction. Further separation of these lipids based on polarity revealed that the modulatory effect is confined to fractions containing free fatty acids. All identified fatty acids were able to individually enhance T-cell proliferation. These data indicate that adipocytes can modulate CD4(+) T-cell function through the release of lipids. Remarkably, free fatty acids were the most prominent modulators of T-cell proliferation, possibly leading to an accumulation of these cells in adipose tissue.
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A4.3 Adipocytes Modulate the Phenotype of Macrophages through Secreted Lipids. Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2013-203217.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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A4.5 Do High Molecular Weight Adiponectin Levels Associate with Radiographic Progression in early Rheumatoid Arthritis and Hand Osteoarthritis? Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2013-203217.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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A4.2 Adipocytes Modulate T Cell Function through Release of Lipids. Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2013-203217.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Macrophages are modulated by factors secreted by adipocytes. Ann Rheum Dis 2012. [DOI: 10.1136/annrheumdis-2011-201238.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Soluble factors derived from infrapatellar fat pad adipocytes of oa patients modulate CD4+T cell cytokine production. Ann Rheum Dis 2012. [DOI: 10.1136/annrheumdis-2011-201238.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Baseline serum adipokine levels predict radiographic progression in early rheumatoid arthritis. ACTA ACUST UNITED AC 2011; 63:2567-74. [PMID: 21567382 DOI: 10.1002/art.30449] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Adipose tissue can secrete soluble mediators (adipokines) with potent immune regulatory functions. Some adipokines have been previously associated with radiographic damage in patients with rheumatoid arthritis (RA). In the present study, we investigated the capacity of baseline adipokine levels to predict radiographic progression over a period of 4 years and studied their contribution relative to that of other known risk factors, such as anti-cyclic citrullinated peptide (anti-CCP) antibodies. METHODS Serum concentrations of leptin, visfatin, resistin, adiponectin, adipsin, tumor necrosis factor α (TNFα), and interleukin-6 (IL-6) were determined in serum samples obtained at baseline from 253 patients with RA from the Early Arthritis Cohort. The association between levels of these adipokines and radiographic progression was determined using a multivariate normal regression model correcting for age, sex, treatment strategy, body mass index (BMI), and the presence of anti-CCP antibodies. RESULTS Levels of IL-6, TNFα, visfatin, and adiponectin were positively associated with radiographic progression over 4 years. This association was independent of BMI. However, only adiponectin levels remained significantly associated with radiographic progression when the model was corrected for the presence of anti-CCP antibodies, whereas a trend was observed for IL-6. The association of both TNFα and visfatin with radiographic damage disappeared after correction for the presence of anti-CCP antibodies, which is consistent with the fact that the levels of both cytokines correlated significantly with anti-CCP antibody levels in these patients. CONCLUSION Our results indicate that adipokines are predictors of radiographic progression in RA, possibly through distinct underlying biologic mechanisms.
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The infrapatellar fat pad of patients with osteoarthritis has an inflammatory phenotype. Ann Rheum Dis 2011; 70:851-7. [PMID: 21242232 DOI: 10.1136/ard.2010.140046] [Citation(s) in RCA: 179] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVES Obesity is a risk factor for the development of osteoarthritis (OA) in hands and knees. Adipose tissue can secrete different adipokines with powerful immunomodulatory effects. The infrapatellar fat pad (IFP) is an intra-articular organ in the vicinity of the synovium and cartilage. It is hypothesised that IFP-derived soluble factors could contribute to pathological processes in the knee joint. A study was therefore undertaken to compare the release of inflammatory mediators in the IFP and subcutaneous adipose tissue (ScAT) and to characterise the adipocytes and immune cell infiltrate in these tissues. METHODS Paired IFP and ScAT samples were obtained from 27 patients with primary OA. The stromal vascular cell fraction (SVF) was isolated and characterised by fluorescence activated cell sorting. Cytokine and adipokine release in fat- and adipocyte-conditioned media was measured by luminex. RESULTS IFP secreted higher levels of inflammatory mediators such as interleukin 6 (IL-6), adipsin, adiponectin and visfatin than ScAT. This could be due to differences in the phenotype of adipocytes and/or in the composition and phenotype of the SVF cells. IFP adipocyte-conditioned media showed a trend towards more IL-6 and adipsin than ScAT. Moreover, the SVF fraction of IFP contained more cells/g tissue, a lower percentage of T cells and a higher percentage of mast cells than ScAT. In addition, T cells had a predominantly pro-inflammatory phenotype while macrophages had a mixed pro- and anti-inflammatory phenotype in the IFP. CONCLUSION There are profound differences in secreted inflammatory factors and immune cell composition between the IFP and ScAT. These data indicate that IFP-derived soluble mediators could contribute to pathophysiological processes in the OA knee joint.
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