Perforin deficiency attenuates collagen-induced arthritis

Granzyme A Contributes to Inflammatory Arthritis in Mice Through Stimulation of Osteoclastogenesis

OBJECTIVE

Granzyme A (GzmA) levels are elevated in the plasma and synovium of patients with rheumatoid arthritis (RA), suggesting involvement of this protease in the pathogenesis of the disease. GzmA contributes to sepsis by regulating the production of proinflammatory cytokines. The purpose of this study was to evaluate the contribution of GzmA to the pathogenesis of RA in vivo and to examine the possibility that GzmA acting via tumor necrosis factor (TNF) stimulates osteoclastogenesis.

METHODS

Inflammatory arthritis induced by type II collagen was evaluated in wild-type, GzmA-deficient, and perforin-deficient mice. The osteoclastogenic potential of GzmA was examined in vitro using bone marrow cells and colony-forming unit-granulocyte-macrophage (CFU-GM) cells and in vivo using GzmA-deficient mice.

RESULTS

Gene deletion of GzmA attenuated collagen-induced arthritis, including serum levels of proinflammatory cytokines, joint damage, and bone erosion in affected mice, suggesting that osteoclast activity is reduced in the absence of GzmA. Accordingly, GzmA-treated bone marrow cells produced multinucleated cells that fulfilled the criteria for mature osteoclasts: tartrate-resistant acid phosphatase (TRAP) activity, β integrin expression, calcitonin receptor expression, and resorptive activity on dentin slices. GzmA appeared to act without accessory cells, and its activity was not affected by osteoprotegerin, suggesting a minor contribution of RANKL. It also induced the expression and secretion of TNF. Neutralization of TNF or stimulation of CFU-GM cells from TNF^-/- mice prevented GzmA-induced osteoclastogenesis. GzmA-deficient mice had reduced osteoclastogenesis in vivo (fewer calcitonin receptor-positive multinucleated cells and fewer transcripts for cathepsin K, matrix metalloproteinase 9, and TRAP in joints) and reduced serum levels of C-terminal telopeptide of type I collagen.

CONCLUSION

GzmA contributes to the joint destruction of RA partly by promoting osteoclast differentiation.

CD3+CD56+ natural killer T cell activity in children with different forms of juvenile idiopathic arthritis and the influence of etanercept treatment on polyarticular subgroup

Juvenile idiopathic arthritis (JIA) has three major onset types with widely varying clinical features. We assessed the natural killer T (NKT) cell function in patients with different JIA subtypes, and found systemic patients exhibited lower NKT cell counts, perforin and granzyme B expression, while the pauciarticular and polyarticular patients displayed higher perforin and granzyme B expression as compared with the controls. The synovial fluid had more NKT cells with higher levels of perforin, granzyme B, and tumour necrosis factor (TNF)-α than peripheral cells. The polyarticular patients that responded to etanercept had lower NKT cell counts, intracellular perforin, granzyme B and the mean fluorescence intensity of TNF-α than the patients that did not respond. Treatment with etanercept reduced the granzyme B and perforin, interferon (IFN)-γ and TNF-α expression in NKT cells in the responsive group. Therefore, a higher NKT cell function may indicate a decreased response to etanercept in polyarticular patients.

Perforin and human diseases

Natural killer (NK) cells and cytotoxic T lymphocytes (CTL) use a highly toxic pore-forming protein perforin (PFN) to destroy cells infected with intracellular pathogens and cells with pre-cancerous transformations. However, mutations of PFN and defects in its expression can cause an abnormal function of the immune system and difficulties in elimination of altered cells. As discussed in this chapter, deficiency of PFN due to the mutations of its gene, PFN1, can be associated with malignancies and severe immune disorders such as familial hemophagocytic lymphohistiocytosis (FHL) and macrophage activation syndrome. On the other hand, overactivity of PFN can turn the immune system against autologous cells resulting in other diseases such as systemic lupus erythematosus, polymyositis, rheumatoid arthritis and cutaneous inflammation. PFN also has a crucial role in the cellular rejection of solid organ allografts and destruction of pancreatic β-cells resulting in type 1 diabetes. These facts highlight the importance of understanding the biochemical characteristics of PFN.

Natural killer cell activity and frequency of killer cell immunoglobulin-like receptors in children with different forms of juvenile idiopathic arthritis

BACKGROUND

Juvenile idiopathic arthritis (JIA) has three major onset types with widely varying clinical features: systemic, polyarticular and pauciarticular. We assessed natural killer (NK) cell function and killer cell immunoglobulin-like receptor (KIR) genotypes in patients with different JIA subtypes.

METHODS

Peripheral blood samples from 72 children with active JIA (systemic, 25; polyarticular, 24; pauciarticular, 23) and 25 controls were used for flow cytometric assessments of NK cell count, cytotoxicity, perforin, granzyme B, interferon (IFN)-γ and tumour necrosis factor (TNF)-α. Samples from 220 children with JIA (systemic, 84; polyarticular, 72; pauciarticular, 64) and 150 controls were used for KIR2DS2, KIR2DS4, KIR3DS1, KIR2DL1, KIR2DL2, KIR2DL3 and KIR3DL1 typing by polymerase chain reaction with sequence-specific oligonucleotide probes.

RESULTS

Compared with the controls, the patients with systemic JIA showed lower NK cell counts, cytotoxicity and perforin and granzyme B expression (p < 0.05), while the patients with pauci- and polyarticular JIA showed higher perforin and granzyme B expression (p < 0.05). NK cells produced higher level of TNF-α while lower level of IFN-γ in the pauci- and polyarticular JIA groups than in the systemic JIA group (p < 0.05). No significant differences in KIR gene frequencies were found between the JIA subgroups and healthy controls, except for the positive frequency and locus frequency of KIR2DS4, which were lower in the systemic JIA group.

CONCLUSIONS

Compared with poly- and pauciarticular JIA, systemic JIA is associated with decreased NK cell function, more IFN-γ and less TNF-α secretion of NK cell and lower KIR2DS4 frequency.

Jagged1 suppresses collagen-induced arthritis by indirectly providing a negative signal in CD8+ T cells

Distinct Notch ligands possess a characteristic ability in terms of functional T cell differentiation. However, the precise role or the therapeutic potential of each Notch ligand in autoimmune diseases is largely unknown. In this study, we examined whether Jagged1 modulates a collagen-induced rheumatoid arthritis (CIA) model by altering T cell responses. The injection of a soluble Jagged1-encoding plasmid, sJag1-P, before or even after initial type II collagen (CII) immunization suppressed the disease severity of CIA. However, this treatment did not suppress CII-specific CD4(+) T cell proliferation and CII-specific Ab production. Depletion of either CD4(+) or CD8(+) T cells ameliorated CIA severity and sJag1-P further improved CIA in CD4(+) but not CD8(+) T cell-depleted mice. Injection of OVA and Jagged1-encoding plasmids inhibited proliferation of OVA-specific granzyme B-producing CD8(+) T cells, although Jagged1 could not directly inhibit CD8(+) T cell proliferation in vitro. The blockade of Jagged1 by an anti-Jagged1 Ab exacerbated CIA, whereas this effect was not observed in the absence of CD8(+) T cells. These data indicate that Jagged1 is able to deliver an indirect negative signal into CD8(+) T cells in vivo, which suggests its therapeutic potential in the treatment of CD8(+) T cell-mediated diseases, including rheumatoid arthritis.

Gait analysis in a murine model of collagen-induced arthritis

Murine collagen-induced arthritis (CIA) has become a valuable animal model for elucidating pathogenic mechanisms and evaluating therapeutic effects for rheumatoid arthritis. Recent advances in digital imaging and computer technology have enabled gait analysis to develop into a powerful tool for objectively detecting functional deficits in human and animal models. The present study explored the use of non-invasive video-capture gait analysis in the evaluation of a murine CIA model. CIA was induced in 45 female DBA/1LacJ mice (8 to 10 weeks old) by immunization with lyophilized bovine articular type II collagen. Gait parameters were determined by ventral plane videography and were correlated to traditional arthritis clinical scores. Our results showed that increases in clinical scores that measure the severity of CIA corresponded to changes in multiple gait parameters that reflect both morphologic (increases in paw area) and functional (increase in stride frequency, decrease in stride length, hind-limb paw placement angle, as well as stride, stance, and braking times) deficits. Our work indicated that the non-invasive video-capture device may be used as a simple and objective data acquisition system for quantifying gait disturbances in CIA mice for the investigation of mechanisms and the evaluation of therapeutic agents.