S41Abstracts

T.9. Disruption of Dendritic Cell-mediated VascularHomeostasis May Contribute to UVB-induced SkinInflammationAnusha Ramanathan1, Sha Tian1, Te-Chen Jenny Tzeng2,Theresa Lu1. 1Hospital for Special Surgery, New York, NY;2Weill Cornell Medical College, New York, NY

Ultraviolet irradiation is known to exacerbate cutaneouslupus lesions. UV irradiation is also known to cause skinresident dendritic cells to leave their niche and migrate todraining lymph nodes. We hypothesized that dendritic cellsmediate vascular homeostasis in skin and that UV irradiationcauses skin inflammation in part by disrupting this dendriticcell-mediated vascular homeostasis. First, we asked aboutthe importance of dendritic cells to vascular homeostasis inskin. Depletion of skin CD11chi cells by injection of diphtheriatoxin into CD11c-DTR mice led to upregulation of VCAM-1 onskin endothelial cells, and upregulation of endothelial cellproliferation, suggesting that CD11chi dendritic cells mediateskin vascular homeostasis. We then asked whether UVBirradiation induced similar findings as in the CD11chi

dendritic cell-depleted mice. Irradiation with UVB light ata single dose of 900 J/m2 resulted in selective depletion ofCD11chi dendritic cells, as well as vasodilation and upregula-tion of VCAM-1 on skin endothelial cells. Together, ourresults suggest that CD11chi dendritic cells regulate vascularquiescence and homeostasis in skin and that UVB irradiationmay cause inflammation by inducing these CD11chi cells tomigrate out of skin. Our results have implications forunderstanding the pathogenesis of lupus skin lesions as wellas for identifying targets for novel therapies.

doi:10.1016/j.clim.2010.03.124

T.10. Imatinib Treatment of Patients with DiffuseCutaneous Systemic Sclerosis Modifies GeneExpression in Peripheral Blood Mononuclear Cells ofClinical RespondersJessica Gordon1, Robert Spiera1, Jamie Mersten1,Jacqueline Salit2, Neil Hackett2, Mary Crow1. 1Hospital forSpecial Surgery, New York, NY; 2Weill-Cornell MedicalCollege, New York, NY

Systemic sclerosis (SSc) is a multisystem, autoimmunedisease in which abnormal signaling through abelson kinase(abl) and the platelet-derived growth factor receptor(PDGFR) contributes to pathologic fibrosis and vasculopathy.Imatinib mesylate (Gleevec™), a tyrosine kinase inhibitor, isa therapy of interest because it can block both pathways. Wehypothesized that imatinib would modulate gene expressionin peripheral blood mononuclear cells (PBMC), and weperformed microarray analysis on PBMC RNA from 5 SScpatients before and after 12 months of treatment. Allpatients are enrolled in an ongoing clinical trial, and thoseselected had clinically meaningful improvements. Patientcharacteristics: 80% female; median age: 44 years [21–52 years]; median disease duration: 1.6 years [0.3–8 years];and median change in Modified Rodnan Skin Score: −9 [−5 to

−11]. RNA was extracted from PBMC and processed formicroarray. A paired t-test was performed using GenespringGX11 and Ingenuity Pathways. Treatment led to differentialexpression of 168 genes at a P value of 0.01 and a fold-changecutoff of 1.2. Of the genes downregulated were severalmembers of the MAP kinase family. Increased expression ofvon Hippel Lindau, HIF1α-inhibitor, and ubiquitin-conjugat-ing enzyme E2V1 transcripts were accompanied by down-regulation of MDM2, demonstrating changes in hypoxiapathway signaling. Decreased expression of calmodulin,NFAT5, PIK3CA, and NLRP3 and increased expression ofCD40 after treatment may signify changes in immuneregulation or signaling. These preliminary data suggest thatimatinib therapy results in modulation of gene expressiondownstream of PDGFR and c-abl as detected in PBMC. Studieswith additional paired samples will extend and confirm thesefindings.

doi:10.1016/j.clim.2010.03.125

T.11. SHIP1 Blocks Crohn's-like IntestinalInflammation in a Murine ModelKeith McLarren1, Shelley Miller1, Nicole Voglmaier1, OanaPopescu2, Laura Sly1. 1Child and Family Research Institute,Vancouver, BC, Canada; 2British Columbia Children'sHospital, Vancouver, BC, Canada

Crohn's disease is an inflammatory disease of thegastrointestinal tract occurring anywhere between themouth and the anus. Fibrosis is a serious complication inpatients with Crohn's disease which can result in strictureformation often requiring surgery. A large challenge in thestudy of Crohn's disease is the lack of acceptable animalmodels. Src homology 2 domain-containing inositol 5′-phosphatase (SHIP1) knockout (−/−) mice are a model ofprofoundly M2 skewed macrophages. We have found thatSHIP1−/− mice spontaneously develop intestinal inflamma-tion that is evident as early as 4 weeks of age and that sharesfeatures with Crohn's disease. Hematoxylin and eosinstaining revealed disease characterized by discontinuous,transmural inflammation, and granuloma in the submucosaand gut-associated lymphoid tissue. In the SHIP1−/− mice,inflammation was restricted to the distal ileum, while colonsand ceca appeared normal. Masson's trichrome staining andSircoll assays for soluble collagen revealed increasedcollagen deposition in SHIP−/− mice compared to wild-typelittermates. Immunohistochemistry for arginase I and Ym1,canonical markers of M2 macrophages, demonstrated ex-pression in cells within the submucosa and lymphoid folliclesand in intestinal epithelial cells. Interestingly, the inflam-mation and increased collagen deposition in SHIP−/− miceoccurred in the distal ileum, the most common site ofsurgical resection required due to fibrosis and strictureformation in patients with Crohn's disease. Characterizationof this new murine model of intestinal inflammation mayprovide a valuable new tool for therapeutic intervention indisease.

doi:10.1016/j.clim.2010.03.126