Neutrophils Sustain Pathogenic CD8+ T Cell Responses in the Heart

Abstract

This study explores the influence of innate immunity on CD8؉ T-cell responses against heart tissue. Adoptive transfer of ovalbumin-specific CD8؉ effector T cells into CMy-mOva mice, which express ovalbumin in cardiac myocytes, results in a lethal acute myocarditis. The inflammatory infiltrate in the heart includes neutrophils as well as T cells. We used anti-Ly6G antibody to transiently deplete neutrophils at the time of onset of disease. By day 7 after receiving 5 ؋ 10 5 CD8؉ effector T cells, 100% of control Ig-treated CMymOva mice had died, while 85% of anti-Ly6G-treated mice survived indefinitely. CD8؉ T-cell infiltration and tissue damage were present in both groups, but the disease was limited in the anti-Ly6G-treated mice, with a rapid disappearance of the adoptively transferred CD8 ؉ T cells within 11 days. Recovery occurred even though blood neutrophil counts began to rise 48 hours after the last anti-Ly6G treatment. Recovery was associated with a chronic CD4 ؉ cell infiltrate, and a rapid decline in expression of IFN-␥ and IP-10 mRNA in the myocardium. Neutrophil depletion did not effect survival of CMy-mOva mice that received 3 ؋ 10 6 CD8 ؉ T cells. These data show that granulocytic inflammation sustains CD8 ؉ T-cell-mediated heart disease, which has important implications for the pathogenesis and treatment of acute myocarditis and allograft rejection.

T-bet Controls Pathogenicity of CTLs in the Heart by Separable Effects on Migration and Effector Activity

“…To explore the possible role of T-bet in the differentiation of pathogenic CD8 ϩ effectors in cardiac disease, we used a transgenic mouse model of CD8 ϩ T cell-mediated myocarditis (cMy-mOVA) (17,18). IL-12 plays a critical role in the differentiation of effector CD8 ϩ T cells that cause disease in cMy-mOVA mice (17).…”

“…Cell suspensions were prepared from spleen and lymph node of OT-I T-bet ϩ/ϩ or OT-I T-bet Ϫ/Ϫ TCRtransgenic mice, and naive OT-I cells were isolated from the suspensions by CD8 magnetic beads (Miltenyi Biotec), as previously described (17,18). The naive T cells were stimulated in vitro with mitomycin-C (SigmaAldrich) treated C57BL/6 spleen cell suspensions (APCs) at a T cell:APC ratio of 1:10, and OVA peptide Ag (SIINFEKL) was added at a final concentration of 1 M/L.…”

“…into cMy-mOVA mice, as previously described (17,18). Cell doses transferred in this study ranged from 0.25 to 1.0 ϫ 10 6 cells per mouse as indicated.…”

“…In contrast to the diffuse inflammatory infiltrate and associated myocyte injury seen in ventricular and atrial walls in recipients of control T cells, there was comparatively minimal myocardial infiltrate in recipients of T-bet Ϫ/Ϫ T cells. Because the inflammatory infiltrate in this model of myocarditis includes a significant number of endogenous leukocytes in addition to the transferred OT-I cells (18), it is possible that comparable numbers of control and T-bet Ϫ/Ϫ OT-I effectors migrated into the hearts, and the differences in the resulting histological appearance and damage are related to impaired ability of the T-bet Ϫ/Ϫ T cells to cause damage and secondary inflammation. To address this possibility, we took advantage of allotypic differences in CD90 between T cell donor and recipient animals to specifically identify the transferred T cells in the cardiac tissue.…”

The arthritis severity quantitative trait locus Cia7 regulates neutrophil migration into inflammatory sites

“…The magnitude of the neutrophilic infiltration of tissues has a significant influence in disease outcome, not only in RA, but also in spondyloarthropathies, 9 other autoimmune and inflammatory diseases such as myocarditis 10 and dermatitis, 11 and bacterial infections 12,13 and endotoxemia. 14,15 Therefore, understanding the regulation of neutrophil influx into inflammatory sites has the potential to identify novel targets for therapeutic intervention in RA, other inflammatory and autoimmune diseases, as well as in responses against microbial pathogens.…”