| 1. |
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| 2. |
- Andersson, KM, et al.
(författare)
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GGTASE DEFICIENT MACROPHAGES ALTER INTEGRIN EXPRESSION ON LYMPHOCYTES AND FACILITATE DEVELOPMENT OF ARTHRITIS
- 2020
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Ingår i: ANNALS OF THE RHEUMATIC DISEASES. - : BMJ. - 0003-4967 .- 1468-2060. ; 79, s. 205-206
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Geranylgeranyltransferase type I (GGTaseI) is the enzyme responsible for the prenylation/ lipidation of the RhoA family proteins, which keeps them attached to the cell membrane. We reported that GGTaseI-deficient (GLC) mice develop a spontaneous and age-dependent arthritis, reproducing the pathology of RA1. Targeting GGTaseI activates RhoA proteins.Objectives:To study which of the activated Rho proteins is responsible for development of arthritis, we deleted individual RhoA, Rac1 or Cdc42 genes in GLC mice. We study consequences of GGTaseI deficiency for lymphocyte function.Methods:Double deficient mice that lack Rac1 (GLC Rac1fl/fl), RhoA (GLC RhoAfl/fl) and Cdc42 (GLC Cdc42fl/fl) were developed by Cre-technology using the LysM-promotor, and were on a mixed genetic background (129Ola/Hsd-C57BL/6)2. Joints of the hind paws were assessed for signs of arthritis histologically and by micro CT at age of 16 weeks. Phenotype of spleen CD4 and CD8 T cells was analysis by flow cytometry. Proliferation and cytokine production was assessed in spleen cultures by ELISA. Gene expression profile was analyzed by RT-PCR.Results:Deletion of Rho proteins had divergent effect on development of arthritis in GLC mice. We observed a reduction of the arthritis index in GLC Rac1fl/fl (n=19, p=0.027) and GLC RhoAfl/fl (n=4, p=0.007) mice compared to GLC (n=16), while GLC Cdc42fl/fl (n=4) had no change in arthritis development. GLC RhoAfl/fl mice increased the bone mass compared to GLC (p=0.029).Flow cytometry analysis showed that RA-prone GLC and GLC Cdc42fl/fl mice had lower number of CD4 cells in spleen. CD4 cells of RA-prone GLC and GLC Cdc42 mice had significantly higher subsets of the regulatory FoxP3+ and FOXp3+CD25+ cells (p=0.016-0.029 and p=0.016-0.029 respectively) compared to control and GLC RhoAfl/fl mice. Additionally, RA-prone mice had higher expression of receptors to extracellular matrix proteins collagen (α2β2) and fibronectin (α5β1) compared to control mice (p=0.016 and p=0.011 resp) and to RA-protected mice (GLC Rac1fl/fl and GLC RhoAfl/fl, p=0.0004 and p=0.011, resp). In total, both the number of FoxP3+ CD4 cells and the expression of α5β1 receptors on CD4 cells correlated strongly with the synovitis score (r=0.72, p=0.0017 and r=0.59, p=0.012, respectively).GGTaseI gene lays under the control of HOX proteins essential for cell homing. Importantly, HOX regulate the expression of integrins. Studying the expression of HoxA genes in spleen, we found that RA prone GLC and GLC Cdc42 mice tended to have lower expression of HoxA2 and higher expression of HoxA9 compared to RA-protected GLC Rac1 and GLC RhoA and to control mice. The Hoxa9/Hoxa2 ratio was significantly higher in RA prone mice compared to RA-protected mice (p=0.0085) and control mice (p=0.019). This ratio correlated with α5β1 receptors (r=0.55, p=0.0084), FOXP3+ CD4 cells (r=0.50, p=0.017), and the arthritis index (r=0.50, p=0.033).Conclusion:Taken together this study shows that Rho proteins play divergent role in development of arthritis. Activation of Rac1 and RhoA by GGTaseI deletion changes the pattern of HOXA proteins and increases expression of integrin receptors, which facilitates leukocyte influx in the paw joints. Deletion of Rac1 and RhoA has RA-protective effect in GLC mice.References:[1]Khan, O.M., et al.J Clin Invest121, 628 (2011).[2]Akula, M.K., et al.Nat Commun10, 3975 (2019).Disclosure of Interests:None declared
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| 3. |
- Malmhall-Bah, E, et al.
(författare)
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RHO EXPRESSION FACILITATES T CELL MIGRATION TO LYMPH NODES IN RESPONSE INFLAMMATION
- 2021
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Ingår i: ANNALS OF THE RHEUMATIC DISEASES. - : BMJ. - 0003-4967 .- 1468-2060. ; 80, s. 12-13
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Deficiency in geranylgeranyltransferase type I (GGTase-I) results in accumulation of active Rho family proteins RhoA, Rac1 and Cdc42, responsible for cell communication and migration. We reported that mice with GGTase-I deficient macrophages (GLC mice) develop a spontaneous and age-dependent arthritis, reproducing pathology of RA [1].Objectives:We study how GGTase-I deficiency in Mø changes T cell phenotype to facilitate their translocation to joints and the development of arthritis.Methods:GLC mice were developed on a mixed genetic background (129Ola/Hsd-C57BL/6) by Cre-technology using LysM-promotor to knockout the Pggt1b gene in Mø[2]. CD4+ cells were isolated from spleen and lymph node (LN) of 16 weeks-old mice (GLC n=7, wt n=5) expected to have high prevalence of arthritis. RNA was extracted to measure expression of the Rho proteins and signature genes to characterize differences in Th-subtypes and migration abilities of CD4+ cells between GLC and wt mice. Furthermore, Illumina RNAseq analyzed the transcriptome of LN CD4+ cells. In a separate experiment we treated GLC mice with CTLA4-FP (n=12) or PBS (n=11) for 20 weeks from the age of 5 weeks. Rationale was to disrupt Mø/T cell contact to prevent arthritis. To study Rho-protein dependent phenotype in human RA, we performed RNAseq of sorted CD4+ cells of RA patients.Results:RNAseq showed that CD4+ cells in LN of GLC mice had IFN-γ dependent cytotoxic profile and upregulated numerous pro-inflammatory genes including Eomes, Cxcr3, Tigit, Tnfsf10, Il-1rl1, Stat1, Jak3, Irf7, Irf5, Ptpn13. Furthermore, the over-represented genes often depended on the IRF family in their transcription.GLC mice overexpressed Cdc42 and Rac1 in spleen CD4+ compared to wt (p=0.005 and p=0.048 resp.). Spleen GLC CD4+ cells had higher levels of α5β1 and α2β2 integrins, strongly correlating to Cdc42 (r= 0.61 p=0.0027 and r=0.50, p=0.018) and arthritis (r=0.64, p=0.0015 and r=0.69, p=0.0004). Importantly, Cdc42, Rac1, and RhoA were higher expressed in LN CD4+ compared to spleen (p=0.016, p=0.031 and p=0.016). In addition, Itgb1 coding for β1 integrin, was upregulated in GLC CD4+ cells of both spleen and LN (p=0.003 p=0.03, resp.), suggesting Rho proteins are important for migration of CD4+ cells to the joint draining LN and for arthritis development. CD4+ cells that migrated to the LN had high proportion of Foxp3+ cells. This also correlated to the expression of Itgb1 (r=0.84, p=0.0012) presenting a plausible mechanism for increased influx of Tregs into joints. Several observations are in favor of this notion. First, GLC mice expressed more Foxp3 in LN compared to spleen CD4+ cells (p=0.016). Second, transcription of Foxp3 in LN CD4+ cells was higher in GLC mice compared to wt (p=0.015). Third, this high Foxp3 coexisted with low transcription of Lef1 (p=0.03), required for Treg immunosuppression. Last, Foxp3 correlated negatively to both Lef1 (r=-0.72, p=0.017), and its cofactor Tcf1 (r=-0.75, p=0.01).CTLA4-FP reduced inflammation in GLC mice evident as lower IFN-γ, IL-6 and TNF-α production (p=0.0002, p<0.0001 and p<0.0001 resp.) and the number of CD25+CD4+cells in spleen (p=0.027). In contrast, we observed increased IL-17A production (p=0.056). However, CTLA4-FP treatment did not affect migration of CD4+ cells enriched with Rho-protein into draining LN nor alleviate arthritis.Similar to the GLC mice, CD4+ cells of RA patients with high expression of RhoA, Rac1 and Cdc42 demonstrated enrichment for Th1 signature genes including IFNG, TBX21, Eomes, IL2RA, IL2RB, IL12RB2, TNF, IL18RAP (all, adj. p<0.05).Conclusion:This study shows that accumulation of Rho-proteins in CD4+ cells results in pro-inflammatory IFN-γ dependent phenotype in mice and human RA. Accumulation of RhoA, Rac1 and Cdc42 proteins trigger the migration of CD4+ cells into joint draining LN and facilitates arthritis. Inhibiting Mø/T cell contact in GLC mice did not suffice to prevent migration of Rho-protein expressing cells and arthritisReferences:[1]Khan, O.M., et al. J Clin Invest, 2011. 121(2): p. 628-39.[2]Akula, M.K., et al. Nat Commun, 2019. 10(1): p. 3975.Disclosure of Interests:None declared
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| 4. |
- Khan, Omar M., 1980, et al.
(författare)
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Geranylgeranyltransferase type I (GGTase-I) deficiency hyperactivates macrophages and induces erosive arthritis in mice.
- 2011
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Ingår i: The Journal of clinical investigation. - 1558-8238. ; 121:2, s. 628-39
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Tidskriftsartikel (refereegranskat)abstract
- RHO family proteins are important for the function of inflammatory cells. They are modified with a 20-carbon geranylgeranyl lipid in a process catalyzed by protein geranylgeranyltransferase type I (GGTase-I). Geranylgeranylation is viewed as essential for the membrane targeting and activity of RHO proteins. Consequently, inhibiting GGTase-I to interfere with RHO protein activity has been proposed as a strategy to treat inflammatory disorders. However, here we show that mice lacking GGTase-I in macrophages develop severe joint inflammation resembling erosive rheumatoid arthritis. The disease was initiated by the GGTase-I-deficient macrophages and was transplantable and reversible in bone marrow transplantation experiments. The cells accumulated high levels of active GTP-bound RAC1, CDC42, and RHOA, and RAC1 remained associated with the plasma membrane. Moreover, GGTase-I deficiency activated p38 and NF-κB and increased the production of proinflammatory cytokines. The results challenge the view that geranylgeranylation is essential for the activity and localization of RHO family proteins and suggest that reduced geranylgeranylation in macrophages can initiate erosive arthritis.
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| 5. |
- Magnusson, Mattias, et al.
(författare)
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Epstein–Barr virus in bone marrow of rheumatoidarthritis patients predicts response to rituximabtreatment
- 2010
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Ingår i: British Journal of Rheumatology. - : Oxford University Press (OUP). - 0263-7103 .- 1460-2172. ; 49, s. 1911-1919
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. Viruses may contribute to RA. This prompted us to monitor viral load and response to anti-CD20 therapy in RA patients.Methods. Blood and bone marrow from 35 RA patients were analysed for CMV, EBV, HSV-1, HSV-2, parvovirus B19 and polyomavirus using real-time PCR before and 3 months after rituximab (RTX) treatment and related to the levels of autoantibodies and B-cell depletion. Clinical response to RTX was defined as decrease in the 28-joint disease activity score (DAS-28) >1.3 at 6 months.Results. Before RTX treatment, EBV was identified in 15 out of 35 patients (EBV-positive group), of which 4 expressed parvovirus. Parvovirus was further detected in eight patients (parvo-positive group). Twelve patients were negative for the analysed viruses. Following RTX, EBV was cleared, whereas parvovirus was unaffected. Eighteen patients were responders, of which 12 were EBV positive. The decrease in the DAS-28 was significantly higher in EBV-positive group compared with parvo-positive group (P = 0.002) and virus-negative patients (P = 0.04). Most of EBV-negative patients that responded to RTX (75%) required retreatment within the following 11 months compared with only 8% of responding EBV-positive patients. A decrease of RF, Ig-producing cells and CD19+ B cells was observed following RTX but did not distinguish between viral infections. However, EBV-infected patients had significantly higher levels of Fas-expressing B cells at baseline as compared with EBV-negative groups.Conclusions. EBV and parvovirus genomes are frequently found in bone marrow of RA patients. The presence of EBV genome was associated with a better clinical response to RTX. Thus, presence of EBV genome may predict clinical response to RTX.
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| 6. |
- Akula, Murali K, et al.
(författare)
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Protein prenylation restrains innate immunity by inhibiting Rac1 effector interactions
- 2019
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Rho family proteins are prenylated by geranylgeranyltransferase type I (GGTase-I), which normally target proteins to membranes for GTP-loading. However, conditional deletion of GGIase-I in mouse macrophages increases GTP-loading of Rho proteins, leading to enhanced inflammatory responses and severe rheumatoid arthritis. Here we show that heterozygous deletion of the Rho family gene Rac1, but not Rhoa and Cdc42, reverses inflammation and arthritis in GGTase-I-deficient mice. Non-prenylated Rac1 has a high affinity for the adaptor protein Ras GTPase-activating-like protein 1 (Iqgap1), which facilitates both GTP exchange and ubiquitination-mediated degradation of Rac1. Consistently, inactivating lagapl normalizes Rac1 GTP-loading, and reduces inflammation and arthritis in GGTase-I-deficient mice, as well as prevents statins from increasing Rac1 GTP-loading and cytokine production in macrophages. We conclude that blocking prenylation stimulates Rac1 effector interactions and unleashes proinflammatory signaling. Our results thus suggest that prenylation normally restrains innate immune responses by preventing Rac1 effector interactions.
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| 7. |
- Andersson, Karin, 1972, et al.
(författare)
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Survivin co-ordinates formation of follicular T-cells acting in synergy with Bcl-6
- 2015
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 6:24, s. 20043-20057
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Tidskriftsartikel (refereegranskat)abstract
- Follicular T helper (Tfh) cells are recognized by the expression of CXCR5 and the transcriptional regulator Bcl-6. Tfh cells control B cell maturation and antibody production, and if deregulated, may lead to autoimmunity. Here, we study the role of the proto-oncogene survivin in the formation of Tfh cells. We show that blood Tfh cells of patients with the autoimmune condition rheumatoid arthritis, have intracellular expression of survivin. Survivin was co-localized with Bcl-6 in the nuclei of CXCR5(+)CD4 lymphocytes and was immunoprecipitated with the Bcl-6 responsive element of the target genes. Inhibition of survivin in arthritic mice led to the reduction of CXCR5(+) Tfh cells and to low production of autoantibodies. Exposure to survivin activated STAT3 and induced enrichment of PD-1(+)Bcl-6(+) subset within Tfh cells. Collectively, our study demonstrates that survivin belongs to the Tfh cell phenotype and ensures their optimal function by regulating transcriptional activity of Bcl-6.
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| 8. |
- Brisslert, Mikael, 1974, et al.
(författare)
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S100A4 regulates the Src-tyrosine kinase dependent differentiation of Th17 cells in rheumatoid arthritis
- 2014
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Ingår i: Biochimica Et Biophysica Acta-Molecular Basis of Disease. - : Elsevier BV. - 0925-4439. ; 1842:11, s. 2049-2059
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To evaluate the role of S100A4, a calcium-binding regulator of nonmuscle myosin assembly, for T-cell responses in rheumatoid arthritis. Methods: Arthritis was induced in the methylated bovine serum albumin (mBSA)-immunized mice lacking the entire S100A4 protein (S100A4KO) and in wild-type counterparts treated with short hairpin ribonucleic acid (shRNA)-lentiviral constructs targeting S100A4 (S100A4-shRNA). The severity of arthritis was evaluated morphologically. T-cell subsets were characterized by the expression of master transcription factors, and functionally by proliferation activity and cytokine production. The activity of the Scr-kinases Fyn and Lck was assessed by the autophosphorylation of C-terminal thyrosine and by the phosphorylation of the CD5 cytodomain. The interaction between S100A4 and the CD5 cytodomain was analysed by nuclear magnetic resonance spectrophotometry. Results: S100A4-deficient mice (S100A4KO and S100A4-shRNA) had significantly alleviated morphological signs of arthritis and joint damage. Leukocyte infiltrates in the arthritic joints of S100A4-deficient mice accumulated Foxp3(+) Treg cells, while the number of ROR gamma t(+) and (pTyr705)STAT3(+) cells was reduced. S100A4-deficient mice had a limited formation of Th17-cells with low retinoic acid orphan receptor gamma t (ROR gamma t) mRNA and IL17 production in T-cell cultures. S100A4-deficient mice had a low expression and activity of T-cell receptor (TCR) inhibitor CD5 and low (pTyr705)STAT3 (signal transducer and activator of transcription 3), which led to increased (pTyr352)ZAP-70 (theta-chain associated protein kinase of 70 kDa), lymphocyte proliferation and production of IL2. In vitro experiments showed that S100A4 directly binds Lck and Fyn and reciprocally regulates their kinase activity towards the CD5 cytodomain. Spectrometry demonstrates an interaction between the CD5 cytodomain and EF2-binding sites of S100A4. Conclusion: The present. study demonstrates that S100A4 plays an important part in the pathogenesis of arthritis. It controls CD5-dependent differentiation of Th17 cells by regulating the activity of the Src-family kinases Lck and Fyn. (C) 2014 Elsevier B.V. All rights reserved.
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| 9. |
- Dehlin, Mats, 1968, et al.
(författare)
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Inhibition of fms-like tyrosine kinase 3 alleviates experimental arthritis by reducing formation of dendritic cells and antigen presentation.
- 2011
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 90:4, s. 811-7
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Tidskriftsartikel (refereegranskat)abstract
- TKs are intracellular signaling molecules essential for cell homeostasis. Inhibition of TKs is used in treatment of malignancies and diabetes mellitus. The present study evaluated the role of Flt3 in antigen-induced arthritis. Mice were immunized with mBSA, and arthritis was induced by an i.a. injection of mBSA. Treatment with the Flt3 inhibitor sunitinib was started together with mBSA immunization or together with the induction of arthritis. The mBSA-injected joints were evaluated morphologically for signs of synovitis and bone/cartilage destruction. Markers of bone metabolism and antibody responses were measured by ELISA. Maturation of DCs in the bone marrow and spleen was evaluated by flow cytometry. Sunitinib treatment reduced the intensity of synovitis and the incidence of bone destruction. The reduction in bone destruction was seen when the treatment was started at the time of immunization or at the time of arthritis induction. The antiarthritic effect was achieved by inhibition of DCs, reduction of antibody production, and bone metabolism. Inhibition of Flt3 is a potent antiarthritic mechanism reducing antigen presentation, synovial inflammation, and bone resorption. Down-regulation of TKs may be a useful tool in the treatment of human RA.
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| 10. |
- Levin, Malin, 1973, et al.
(författare)
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Rip2 deficiency leads to increased atherosclerosis despite decreased inflammation.
- 2011
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Ingår i: Circulation research. - 1524-4571. ; 109:11, s. 1210-8
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Tidskriftsartikel (refereegranskat)abstract
- The innate immune system and in particular the pattern-recognition receptors Toll-like receptors have recently been linked to atherosclerosis. Consequently, inhibition of various signaling molecules downstream of the Toll-like receptors has been tested as a strategy to prevent progression of atherosclerosis. Receptor-interacting protein 2 (Rip2) is a serine/threonine kinase that is involved in multiple nuclear factor-κB (NFκB) activation pathways, including Toll-like receptors, and is therefore an interesting potential target for pharmaceutical intervention.
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| 11. |
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| 12. |
- Svensson, Mattias, 1982, et al.
(författare)
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Fms-like tyrosine kinase 3 ligand controls formation of regulatory T cells in autoimmune arthritis.
- 2013
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Fms-like tyrosine kinase 3 ligand (Flt3L) is known as the primary differentiation and survival factor for dendritic cells (DCs). Furthermore, Flt3L is involved in the homeostatic feedback loop between DCs and regulatory T cell (Treg). We have previously shown that Flt3L accumulates in the synovial fluid in rheumatoid arthritis (RA) and that local exposure to Flt3L aggravates arthritis in mice, suggesting a possible involvement in RA pathogenesis. In the present study we investigated the role of Flt3L on DC populations, Tregs as well as inflammatory responses in experimental antigen-induced arthritis. Arthritis was induced in mBSA-immunized mice by local knee injection of mBSA and Flt3L was provided by daily intraperitoneal injections. Flow cytometry analysis of spleen and lymph nodes revealed an increased formation of DCs and subsequently Tregs in mice treated with Flt3L. Flt3L-treatment was also associated with a reduced production of mBSA specific antibodies and reduced levels of the pro-inflammatory cytokines IL-6 and TNF-α. Morphological evaluation of mBSA injected joints revealed reduced joint destruction in Flt3L treated mice. The role of DCs in mBSA arthritis was further challenged in an adoptive transfer experiment. Transfer of DCs in combination with T-cells from mBSA immunized mice, predisposed naïve recipients for arthritis and production of mBSA specific antibodies. We provide experimental evidence that Flt3L has potent immunoregulatory properties. Flt3L facilitates formation of Treg cells and by this mechanism reduces severity of antigen-induced arthritis in mice. We suggest that high systemic levels of Flt3L have potential to modulate autoreactivity and autoimmunity.
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