Relapsing polychondritis, induced in mice with matrilin 1, is an antibody- and complement-dependent disease

Abstract

Relapsing polychondritis is an autoimmune disease that affects cartilage in the ear, nose, and respiratory tract. A pathogenic immune response has been proposed and antibodies to several cartilage proteins are detected in sera from these patients. To investigate the role of the humoral immune response in relapsing polychondritis, we used the matrilin-1-induced relapsing polychondritis model. Mice deficient of B cells (muMT) and mice congenic at the complement factor 5, were immunized with matrilin-1, a cartilage-specific protein mainly detected in the tracheal cartilage. To investigate the binding properties and tissue selection of matrilin-1-specific antibodies we produced matrilin-1-specific B-cell hybridomas. Although 83% of the micro MT heterozygous mice developed respiratory distress and erosive chondritis in the respiratory tract, none of the B-cell-deficient mice were susceptible to disease. In addition, we show that complement factor 5 is important for the induction of matrilin-1-induced relapsing polychondritis. Monoclonal matrilin-1-specific antibodies injected into neonatal mice bound specifically to cartilage of the respiratory tract and adult B-cell-deficient mice injected with the same antibodies developed erosive chondritis in the respiratory tract. We conclude that relapsing polychondritis can be mediated by a pathway involving tissue-specific antibodies and complement activation.

Figure 1

Disease course of mice immunized with matrilin-1. B-cell-deficient (homozygous) and B-cell-sufficient (heterozygous) μMT mice on a B10.Q background are scored for respiratory distress. A: Incidence. B: Mean clinical score of all mice. C and D: Clinical scores of two individual mice with a characteristic relapsing disease. For clinical score see Material and Methods.

Figure 2

Tissue sections from a μMT-B10.Q-sufficient (heterozygous) mouse, immunized with matrilin-1. A and B: Tracheal tissue with a destructed tracheal ring (A) and inflammatory infiltrate in nasal tissue (B), both from the acute phase of the disease. C: Section from laryngeal cartilage 140 days after immunization. C, Cartilage tissue; I, inflammatory infiltrate. Staining with hematoxylin and erythrosine. Original magnifications: ×75 (A, C); ×200 (B).

Figure 3

Inhibition assay of five matrilin-1-specific monoclonal antibodies. Five clones (AM2, AM4, AM5, AM7, and AM8) were produced and tested for cross-reactivity. The results of the enzyme-linked immunosorbent assay are presented as percentage of inhibition when blocking a biotinylated antibody with a nonbiotinylated antibody.

Figure 4

Tissue sections from neonatal mice that were injected with matrilin-1-specific monoclonal antibodies. A: Laryngeal cartilage from a neonate injected with AM5. B: Hind paw from a neonate injected with AM5. Background staining with methyl green. Original magnifications: ×65 (A); ×170 (B).

Figure 5

Tissue sections from a μMT-QD B-cell-deficient (homozygous) mouse that was injected with matrilin-1-specific monoclonal antibodies. A: Tissue section from laryngeal cartilage showing an erosive inflammation. B: Nasal tissue showing an inflammatory infiltrate in the mucosal part of the septum. C, Cartilage; I, inflammatory infiltrate. Staining with hematoxylin and erythrosine. Original magnifications, ×180.

Figure 6

Serum levels of matrilin-1-specific antibodies in mice immunized with matrilin-1. Sera were diluted 1/10,000 in all assays except for sera from day 77 detecting IgG1 and IgG2a, which were diluted 1/1000. Titers are expressed as OD values detecting IgG Fcγ (A), IgG1 (B), and IgG2a/c (C).