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LRRK2 is an Interferon-gamma Target Involved in Immune Responses
S56 revealed that the rhodamine-labelled Herceptin®-conjugated liposomes specifically targeted breast carcinoma cells. However, to a lower degree, binding also to Her-2/ neu negative prostate carcinoma cell line DU145 as control. Antibody-conjugated cationic liposomes delivering CD59 siRNAs induced a significant down-regulation of CD59 protein on BT474 cells after 72 h as assessed by quantitative flow cytometry but also reduced the level of the complement regulator on control cells. The reduced regulatory potential led to a significant augmentation of antibody-induced complement-dependent tumor cell killing of BT474 cells but had no effect on control DU145 cells. Experiments are on the way to optimize the liposome formula to eliminate unwanted unspecific tissue binding. doi:10.1016/j.clim.2010.03.169
T.56. Loss of LPA1 Signaling Protects Against Dermal Fibrosis in a Mouse Model of Systemic Sclerosis Flavia Castelino 1, Sarah Brooks 1, Manuela Funke 1, Jerold Chun 2, Andrew Luster 1, Andrew Martin Tager 1. 1 Massachusetts General Hospital, Boston, MA; 2Scripps Research Institute, La Jolla, CA Systemic sclerosis or scleroderma is a potentially fatal autoimmune disease of unknown etiology, which is clinically characterized by vasculopathy and progressive multiorgan fibrosis. To date, there are no effective therapies. We have previously shown that the lipid mediator, lysophosphatidic acid (LPA) plays a key role in the development of pulmonary fibrosis. Here, we studied the involvement of LPA and two of its G protein-coupled transmembrane spanning receptors, LPA1 and LPA2, in the development of dermal fibrosis in a bleomycin-induced mouse model of systemic sclerosis using mice deficient in these receptors. LPA1-deficient (LPA1 KO) mice were resistant to the dermal fibrosis induced by repetitive bleomycin injection in wild type (WT) mice. WT mice demonstrated an increase in dermal thickness and collagen content compared to KO mice. The number of myofibroblasts and phospho-Smad2 positive cells after bleomycin was also significantly greater in WT than in LPA1 KO mice. Deletion of LPA2, however, did not confer any protection from bleomycin-induced fibrosis as both LPA2 KO and WT mice developed an increase in dermal fibrosis. In addition, treatment of bleomycin injected C57Bl/6 mice with an LPA1 inhibitor (AP-103095) resulted in amelioration of dermal fibrosis. These results suggest that LPA1, but not LPA2, is required for bleomycin-induced dermal fibrosis. Mechanisms for this may include an increase in myofibroblast accumulation and/or an increase in TGF-β signaling. Targeting the LPA–LPA1 pathway has the potential to be an effective new therapeutic strategy for scleroderma. doi:10.1016/j.clim.2010.03.170
Abstracts
T.57. LRRK2 is an Interferon-gamma Target Involved in Immune Responses Agnes Gardet 1, Yair Benita 1, Isabel Ballester 1, Bruce Sands 1, Joshua Korzenik 1, Mark Daly 1, Ramnik Xavier 1, Daniel Podolsky 2. 1Massachusetts General Hospital, Boston, MA; 2UT Southwestern Medical Center, Dallas, TX Leucine-rich repeat (LRR) domains are structural motifs that can mediate protein–protein interactions. Some LRRcontaining proteins, such as TLRs, play important roles in innate immunity by triggering of signalling pathways in response to pathogens. Genome-wide association studies described a SNP associated with Crohn's disease (CD) which is located upstream from a gene encoding an LRR-containing protein, LRRK2 (leucine-rich repeat kinase 2). Mutations in LRRK2 have been involved in Parkinson's disease. We investigated whether LRRK2 might be involved in immune responses. Our data show that LRRK2 is expressed at low levels in various cell lines but enriched in immune cells. LRRK2 expression is highly upregulated in macrophages after IFN-γ stimulation (23.6-fold increase after 24 h, P b 0.001) and also in inflamed tissues from CD patients vs noninflamed tissues (5.1-fold increase P = 0.002). Immunostaining of patient's intestinal biopsies demonstrates that LRRK2 is expressed in the lamina propria within macrophages, B-cells and dendritic cells. LRRK2 is localized in the endosomal compartments in the macrophages and colocalized with Salmonella typhimurium bacteria after 30 minutes of infection. Luciferase reporter assays and knockdown experiments show that LRRK2 is able to activate pathways involved in immune responses such as NF-κB and NFAT pathways and reactive oxygen species production. Our data contain the first evidences suggesting that LRRK2 is involved in some inflammation process. Dysregulation of LRRK2 in immune responses should be investigated in the context of Crohn's disease as well as Parkinson's disease. doi:10.1016/j.clim.2010.03.171
T.58. The Role of IL-2–ICOS Pathway in the Functional Stability of Regulatory T Cells in Organ Specific Autoimmunity Mara Kornete, Evridiki Sgouroudis, Ciriaco Piccirillo. McGill University, Montreal, QC, Canada Many studies indicate a progressive waning in Treg cell functions, rather than frequency, as a potential trigger of T1D pathogenesis. We have shown that T1D progression is associated with a temporal loss in the capacity of CD4+Foxp3+ Treg cells to expand/survive in beta-islets, which in turn perturbs the Treg/Teff cell balance and unleashes the anti-islet immune responses. A deficiency in IL-2 was shown to trigger the defective function of Treg cells in islets. Moreover, ICOS blockade in NOD neonates exacerbates T1D, indicating an important role of ICOS in Treg function. IL-2 is known to enhance ICOS expression on activated T cells, suggesting that a feedback loop
T.56. Loss of LPA1 Signaling Protects Against Dermal Fibrosis in a Mouse Model of Systemic Sclerosis Flavia Castelino 1, Sarah Brooks 1, Manuela Funke 1, Jerold Chun 2, Andrew Luster 1, Andrew Martin Tager 1. 1 Massachusetts General Hospital, Boston, MA; 2Scripps Research Institute, La Jolla, CA Systemic sclerosis or scleroderma is a potentially fatal autoimmune disease of unknown etiology, which is clinically characterized by vasculopathy and progressive multiorgan fibrosis. To date, there are no effective therapies. We have previously shown that the lipid mediator, lysophosphatidic acid (LPA) plays a key role in the development of pulmonary fibrosis. Here, we studied the involvement of LPA and two of its G protein-coupled transmembrane spanning receptors, LPA1 and LPA2, in the development of dermal fibrosis in a bleomycin-induced mouse model of systemic sclerosis using mice deficient in these receptors. LPA1-deficient (LPA1 KO) mice were resistant to the dermal fibrosis induced by repetitive bleomycin injection in wild type (WT) mice. WT mice demonstrated an increase in dermal thickness and collagen content compared to KO mice. The number of myofibroblasts and phospho-Smad2 positive cells after bleomycin was also significantly greater in WT than in LPA1 KO mice. Deletion of LPA2, however, did not confer any protection from bleomycin-induced fibrosis as both LPA2 KO and WT mice developed an increase in dermal fibrosis. In addition, treatment of bleomycin injected C57Bl/6 mice with an LPA1 inhibitor (AP-103095) resulted in amelioration of dermal fibrosis. These results suggest that LPA1, but not LPA2, is required for bleomycin-induced dermal fibrosis. Mechanisms for this may include an increase in myofibroblast accumulation and/or an increase in TGF-β signaling. Targeting the LPA–LPA1 pathway has the potential to be an effective new therapeutic strategy for scleroderma. doi:10.1016/j.clim.2010.03.170
Abstracts
T.57. LRRK2 is an Interferon-gamma Target Involved in Immune Responses Agnes Gardet 1, Yair Benita 1, Isabel Ballester 1, Bruce Sands 1, Joshua Korzenik 1, Mark Daly 1, Ramnik Xavier 1, Daniel Podolsky 2. 1Massachusetts General Hospital, Boston, MA; 2UT Southwestern Medical Center, Dallas, TX Leucine-rich repeat (LRR) domains are structural motifs that can mediate protein–protein interactions. Some LRRcontaining proteins, such as TLRs, play important roles in innate immunity by triggering of signalling pathways in response to pathogens. Genome-wide association studies described a SNP associated with Crohn's disease (CD) which is located upstream from a gene encoding an LRR-containing protein, LRRK2 (leucine-rich repeat kinase 2). Mutations in LRRK2 have been involved in Parkinson's disease. We investigated whether LRRK2 might be involved in immune responses. Our data show that LRRK2 is expressed at low levels in various cell lines but enriched in immune cells. LRRK2 expression is highly upregulated in macrophages after IFN-γ stimulation (23.6-fold increase after 24 h, P b 0.001) and also in inflamed tissues from CD patients vs noninflamed tissues (5.1-fold increase P = 0.002). Immunostaining of patient's intestinal biopsies demonstrates that LRRK2 is expressed in the lamina propria within macrophages, B-cells and dendritic cells. LRRK2 is localized in the endosomal compartments in the macrophages and colocalized with Salmonella typhimurium bacteria after 30 minutes of infection. Luciferase reporter assays and knockdown experiments show that LRRK2 is able to activate pathways involved in immune responses such as NF-κB and NFAT pathways and reactive oxygen species production. Our data contain the first evidences suggesting that LRRK2 is involved in some inflammation process. Dysregulation of LRRK2 in immune responses should be investigated in the context of Crohn's disease as well as Parkinson's disease. doi:10.1016/j.clim.2010.03.171
T.58. The Role of IL-2–ICOS Pathway in the Functional Stability of Regulatory T Cells in Organ Specific Autoimmunity Mara Kornete, Evridiki Sgouroudis, Ciriaco Piccirillo. McGill University, Montreal, QC, Canada Many studies indicate a progressive waning in Treg cell functions, rather than frequency, as a potential trigger of T1D pathogenesis. We have shown that T1D progression is associated with a temporal loss in the capacity of CD4+Foxp3+ Treg cells to expand/survive in beta-islets, which in turn perturbs the Treg/Teff cell balance and unleashes the anti-islet immune responses. A deficiency in IL-2 was shown to trigger the defective function of Treg cells in islets. Moreover, ICOS blockade in NOD neonates exacerbates T1D, indicating an important role of ICOS in Treg function. IL-2 is known to enhance ICOS expression on activated T cells, suggesting that a feedback loop