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.


The IL13/IL4RA/CCL2 Pathway Drives Sclerodermatous Graft Versus Host Disease in Mice and Correlates with Disease Activity in Scleroderma Patients.

Aliprantis4,  Antonios O., Greenblatt3,  Matthew, Sargent2,  Jennifer, Farina6,  Giuseppina, Tsang3,  Kelly, Lafyatis1,  Robert A., Whitfield2,  Michael

Boston University School of Medicine, Arlington, MA
Department of Genetics, Dartmouth Medical School
Department of Immunology and Infectious Diseases, Harvard School of Public Health
Department of Medicine, Division of Rheumatology, Allergy and Immunology, Brigham and Women's Hospital and Harvard Medical School and Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA
Department of Medicine, Division of Rheumatology, Allergy and Immunology, Brigham and Women's Hospital and Harvard Medical School and Department of Immunology and Infectious Diseases, Harvard School of Public Health
Rheumatology Section, Boston University School of Medicine

Background:

Scleroderma (SSc) is an irreversible autoimmune disease characterized by tissue fibrosis. Agents to treat SSc remain elusive since mechanisms underlying the initiation and propagation of fibrosis are not well understood. We have shown that the gene expression profile of murine sclerodermatous graft-versus-host disease (sclGVHD) approximates an "inflammatory" subset of human SSc patients and that both diseases display activation of the IL13 cytokine pathway. Here, the function of the IL13 pathway and downstream CCL2 expression is defined in the mouse model and SSc patients.

Methods:

SclGVHD was induced by injection of splenocytes from allogeneic B10.D2 mice into MHC-matched BALB/c Rag2-/-, BALB/c Rag2-/-IL13-/- or BALB/c Rag2-/-IL4Ra-/- hosts. Control hosts received syngeneic BALB/c splenocytes. Recipient mice were scored biweekly for development of clinical sclGVHD. At 6 weeks, a blinded SSc expert scored back skin histopathology. Explant cultures and experiments on FACS sorted cells isolated from back skin were performed 2 or 3 weeks after cell transfer. Human SSc skin RNA was purified from a cohort of patients with a mean disease duration of 24 months. ELISA or quantitative RT-PCR was used to detect gene expression. Centocor, Inc provided previously published blocking antibodies to CCL2 and CCL12.

Results:

Compared to syngeneic controls, explant cultures of back skin from sclGVHD mice displayed robust IL13 production confirming expression of this cytokine at the major site of pathology. Consistent with this, Rag2-/-IL13-/- hosts were partially protected from the development of sclGVHD. Partial protection suggested redundant expression of IL13 by both host and graft sources. Accordingly, both host macrophage and graft T-cell populations were found to produce IL13 in lesional skin. In contrast to Rag2-/-IL13-/- hosts, those lacking the ability to respond to IL13 (Rag2-/-IL4Ra-/-) were nearly completely protected from sclGVHD. Protection was associated with increased production of the anti-inflammatory cytokine IL-10 by graft T-cells isolated from Rag2-/-IL4Ra-/- hosts. Comparative expression profiling of Rag2-/- and Rag2-/-IL4Ra-/- sclGVHD mice also revealed that the latter displayed reduced CCL2 expression in whole skin, as well as in purified macrophage and CD45- stromal cell populations. Parallel exploration of additional datasets, including IL13 stimulated human dermal fibroblasts and IL13 transgenic mice, also suggested CCL2 as a common target of IL13 pathway activation. Confirming the functional significance of this finding, co-treatment with blocking antibodies to CCL2 and its murine homolog CCL12 prevented sclGVHD. Lastly, we show that expression of receptor subunits for IL13 signaling (IL13RA1 and IL4RA) and CCL2 are significantly increased in the skin of SSc patients and correlate with modified Rodnan skin scores, a clinical measure of cutaneous disease.

Conclusions:

These data provide evidence that the IL13/IL4Ra/CCL2 axis is important to SSc pathogenesis. Inhibition of this pathway may be a viable therapeutic option for SSc patients exhibiting the inflammatory gene signature.

To cite this abstract, please use the following information:
Aliprantis, Antonios O., Greenblatt, Matthew, Sargent, Jennifer, Farina, Giuseppina, Tsang, Kelly, Lafyatis, Robert A., et al; The IL13/IL4RA/CCL2 Pathway Drives Sclerodermatous Graft Versus Host Disease in Mice and Correlates with Disease Activity in Scleroderma Patients. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :675
DOI: 10.1002/art.28443

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