Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Lipid-Cytokine-Chemokine Cascade Drives Neutrophil Recruitment in a Murine Model of Inflammatory Arthritis.

Kim3,  Nancy D., Chou1,  Richard C., Sadik2,  Christian, Seung2,  Edward, Lan2,  Yinan, Iwakura4,  Yoichiro, Luster2,  Andrew

Dartmouth-Hitchcock Medical Center, Lebanon, NH
Massachusetts General Hospital
Massachusetts General Hospital, Boston, MA
University of Tokyo

Purpose:

A diverse array of chemoattractants control leukocyte trafficking, but how these apparently redundant signals collaborate in vivo is still unknown. We previously demonstrated an absolute requirement for the lipid chemoattractant leukotriene B4 (LTB4) and its receptor BLT1 for neutrophil recruitment into the joint in the development of immune complex-induced arthritis. The purpose of these studies was to further dissect the sequential roles of LTB4, IL-1b, and chemokine signaling in neutrophil recruitment in this model of inflammatory arthritis.

Methods:

Using the K/BxN serum transfer arthritis mouse model, K/BxN serum was injected into C57Bl/6, BLT1-/-, CXCR2-/-, CCR1-/-, and CXCR2-/-/CCR1-/- mice, and arthritis was assessed by hind paw measurement and clinical scoring. Bone marrow neutrophils from IL-1a/b-/- mice were purified and injected for neutrophil adoptive transfer studies. On designated days, synovial fluid leukocytes and neutrophils and synovial tissue were isolated, and chemokine, chemokine receptor, and cytokine transcription and production were analyzed by quantitative PCR and ELISA. Primary murine fibroblast-like synoviocytes (FLS), endothelial cells, and macrophages were stimulated in vitro with recombinant murine IL1-1b or TNF-a, and neutrophil-active chemokine expression was measured by qPCR.

Results:

Synovial fluid analysis demonstrated that CCR1 was the predominant neutrophil chemokine receptor in the early phase of disease, and CXCR2 was the predominant neutrophil chemokine receptor in established disease. Synovial fluid neutrophils produced IL-1b and the neutrophil-active chemokines CCL3/MIP-1a and CXCL2/MIP-2. In contrast, synovial tissue expressed greater proportions of the neutrophil-active chemokines CXCL1/KC and CXCL5/LIX. Adoptive transfer of IL-1a/b-/- neutrophils into BLT1-/- mice was not able to restore disease or chemokine expression. In vitro IL-1b-stimulated FLS and endothelial cells expressed primarily CXCL5/LIX and CXCL1/KC, respectively. Finally, upon induction of K/BxN serum transfer arthritis, CCR1-/- mice had delayed and attenuated disease compared with wild-type mice, while CXCR2-/- mice had normal onset of disease that quickly waned. Importantly, deletion of both CCR1 and CXCR2 in the mice completely abrogated arthritis development.

Conclusions:

In this model of acute autoantibody-induced arthritis, we uncovered a sequence of events in which a lipid receptor (BLT1) initiates disease by promoting the influx of neutrophils producing IL-1b, which then induces CXCL1/KC and CXCL5/LIX from surrounding synovial tissue. Synovial fluid leukocytes themselves also produce CCL4/MIP-1b and CXCL2/MIP-2, promoting further neutrophil trafficking into the joint. CCR1 and CXCR2 operate in series to mediate all chemokine-dependent neutrophil recruitment. Thus, we have demonstrated that neutrophil trafficking into the joint is a tightly regulated process requiring the sequential involvement of multiple cytokine and chemoattractant pathways.

To cite this abstract, please use the following information:
Kim, Nancy D., Chou, Richard C., Sadik, Christian, Seung, Edward, Lan, Yinan, Iwakura, Yoichiro, et al; Lipid-Cytokine-Chemokine Cascade Drives Neutrophil Recruitment in a Murine Model of Inflammatory Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1427
DOI: 10.1002/art.29193

Abstract Supplement

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