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Previous reports have demonstrated the ability of antigen-presenting cells (APCs), genetically modified to express Fas ligand (FasL), to inhibit T-cell responses through the induction of apoptosis of antigen-specific T cells. Here we have examined the ability of primary mouse bone marrow-derived dendritic cells (DCs), genetically modified by adenoviral infection to express FasL, to inhibit progression of established collagen-induced arthritis (CIA) in DBA/1 mice. Systemic injection of DC/FasL into mice with established CIA resulted in substantial disease amelioration as determined by analysis of paw swelling, arthritic index, and number of arthritic paws. Moreover, a single injection of DC/FasL resulted in extended suppression of disease. We also demonstrate that treatment of arthritic mice with DC/FasL suppressed interferon-gamma (IFN-gamma) production from spleen-derived lymphocytes and reduced T-cell proliferation following collagen stimulation without affecting the levels of anti-collagen antibody isotypes. These results demonstrate that systemic administration of DC/FasL is able to suppress collagen-reactive T cells, resulting in effective and sustained treatment of established CIA.

Robust cellular bioenergetics is vital in the energy-demanding process of maintaining matrix homeostasis in the intervertebral disc. Age-related decline in disc cellular bioenergetics is hypothesised to contribute to the matrix homeostatic perturbation observed in intervertebral disc degeneration. The present study aimed to measure how ageing impacted disc cell mitochondria and bioenergetics. Age-related changes measured included matrix content and cellularity in disc tissue, as well as matrix synthesis, cell proliferation and senescence markers in cell cultures derived from annulus fibrosus (AF) and nucleus pulposus (NP) isolated from the discs of young (6-9 months) and older (36-50 months) New Zealand White rabbits. Cellular bioenergetic parameters were measured using a Seahorse XFe96 Analyzer, in addition to quantitating mitochondrial morphological changes and membrane potential. Ageing reduced mitochondrial number and membrane potential in both cell types. Also, it significantly reduced glycolytic capacity, mitochondrial reserve capacity, maximum aerobic capacity and non-glucose-dependent respiration in NP. Moreover, NP cells exhibited age-related decline in matrix synthesis and reduced cellularity in older tissues. Despite a lack of changes in mitochondrial respiration with age, AF cells showed an increase in glycolysis and altered matrix production. While previous studies report age-related matrix degenerative changes in disc cells, the present study revealed, for the first time, that ageing affected mitochondrial number and function, particularly in NP cells. Consequently, age-related bioenergetic changes may contribute to the functional alterations in aged NP cells that underlie disc degeneration.