Invariant natural killer T cells are natural regulators of murine spondylarthritis

Abstract

Objective. To investigate the role of invariant natural killer T (iNKT) cells in TNF⌬ARE/؉ mice, an animal model of spondylarthritis (SpA) with both gut and joint inflammation.Methods. The frequency and activation of iNKT cells were analyzed on mononuclear cells from the lymph nodes and livers of mice, using flow cytometry with ␣-galactosylceramide/CD1d tetramers and quantitative polymerase chain reaction for the invariant V ␣ 14-J ␣ 18 rearrangement. Bone marrow-derived dendritic cells (DCs) were obtained by expansion of primary cells with granulocyte-macrophage colony-stimulating factor followed by coculture with iNKT cell hybridomas, and interleukin-2 release into the cocultures was then measured by enzyme-linked immunosorbent assay (ELISA). Cytokine levels were determined by ELISA or cytometric bead array analyses of freshly isolated DCs and iNKT cells in mixed cocultures. TNF ⌬ARE/؉ mice were backcrossed onto J ␣ 18 ؊/؊ and CD1d ؊/؊ mice, and disease onset was evaluated by clinical scoring, positron emission tomography, and histology. CD1d levels were analyzed on mononuclear cells in paired blood and synovial fluid samples from patients with SpA compared with healthy control subjects. Results. In the absence of iNKT cells, symptoms of gut and joint inflammation in TNF⌬ARE/؉ mice were aggravated. Invariant NKT cells were activated during the course of the disease. This was linked to an enrichment of inflammatory DCs, characterized by high levels of CD1d, particularly at draining sites of inflammation. A similar increase in CD1d levels was observed on DCs from patients with SpA. Inflammatory DCs from TNF ⌬ARE/؉ mice stimulated iNKT cells to produce immunomodulatory cytokines, in the absence of exogenous stimulation. Prolonged, continuous exposure, but not short-term exposure, to tumor necrosis factor (TNF) was found to be responsible for the enhanced DC-NKT cell crosstalk.Conclusion. This mode of iNKT cell activation represents a natural counterregulatory mechanism for the dampening of TNF-driven inflammation.The spondylarthritides (SpA) are a group of chronic inflammatory disorders that primarily affect the joints and are accompanied by a variety of extraarticular manifestations, such as intestinal and ocular inflammation. Joint symptoms include peripheral arthritis and enthesitis (1), sacroiliitis and spondylitis, and new bone formation leading to ankylosis. There is major overlap between the different clinical entities of SpA, and familial clustering has been observed. Mechanisms contributing to their pathogenesis include genetic predisposition (linked to various factors, including HLA-B27, interleukin-23 receptor , and aminopeptidase regulator of tumor necrosis factor [TNF] receptor 1 shedding [ARTS1], among others) and certain environ-

Spondyloarthritis: may the force be with you?

“…Careful histological evaluation in early disease confirmed an enthesitis-based peripheral arthritis at three different locations, including interphalangeal joints, Achilles tendons and the hip joints. As previously shown by this group, arthritis development was independent of the adaptive immune response as it also developed in RAG1 knockout mice, which lack T lymphocytes 11. Histological evaluation of animals in the later stages of disease showed extensive secondary synovitis and bone erosion.…”

Mechanisms Regulating TNF-Driven Gut and Joint Inflammation

“…Chronic iNKT cell activation through this pathway was found to attenuate Crohn's like ileitis and joint inflammation. These findings may therefore represent a naturally occurring counter regulatory mechanism to dampen TNF-driven inflammation [44].…”

A bidirectional crosstalk between iNKT cells and adipocytes mediated by leptin modulates susceptibility for T cell mediated hepatitis

“…Lymphocytes were additionally stained with 7-AAD (BD), anti-mouse TCR-b antibody (eBioscience) and a-GalCer-loaded CD1d tetramers to gate on viable T cells (7-AAD À TCRb + Tetramer À ) and iNKT cells (7-AAD À TCRb + Tetramer + ) as described before [18]. Samples were measured on a FACS Canto II (BD Biosciences) and analyzed using FlowJo analysis software (Tree Star Inc., Ashland, Oregon, USA).…”

“…Hepatic lymphocyte and splenocytes were isolated as described previously [18] and were further used for flow cytometry, in vitro cell cultures or iNKT cell purification. Splenic lymphocytes (6 Â 10 5 ) were cultured in presence of a-GalCer (200 ng/ml) and the supernatant was collected after 72 or 96 h for cytokine quantification.…”