ABSTRACT
2-Chlorodeoxyadenosine (cladribine, CdA) is an immunosuppressive drug that is licensed to treat hairy cell leukaemia, and has been shown recently to have beneficial effects in patients with multiple sclerosis (MS). The therapeutic effects of CdA have been suggested to be mediated partly through its potent toxicity towards lymphocytes. However, the effects of CdA on other immune cells are poorly understood. In the present study, we investigated the effects of CdA on the induction of apoptosis in human monocytes, monocyte-derived immature (ImDC) and mature (mDC) dendritic cells. Treatment of monocytes with CdA strongly induced apoptosis after 24 h, while apoptosis induction in DC was evident after 72 h. Furthermore, CdA treatment strongly induced caspase-3 and caspase-9 in monocytes, whereas activation of caspases was undetected in DC. The mitochondrial membrane potential in DC was reduced significantly after CdA treatment. DNA hypodiploid assessment showed fragmented nuclei in DC after CdA treatment together with activation of p53 protein. These results revealed that CdA induces caspase-independent apoptosis in DC and suggest cell type specific effects of CdA. This mechanism may contribute to the effect of CdA in autoimmune diseases.
Subject(s)
Cladribine/pharmacology , Dendritic Cells/drug effects , Immunosuppressive Agents/pharmacology , Leukemia, Hairy Cell/drug therapy , Monocytes/drug effects , Multiple Sclerosis/drug therapy , Apoptosis/drug effects , Caspase 3/genetics , Caspase 3/metabolism , Caspase 9/genetics , Caspase 9/metabolism , Cell Differentiation , Cells, Cultured , Cladribine/therapeutic use , DNA Damage/drug effects , Dendritic Cells/immunology , Humans , Membrane Potential, Mitochondrial/drug effects , Monocytes/immunology , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolismABSTRACT
In multiple sclerosis (MS) matrix metalloproteinases (MMP) are believed to be involved in the disruption of the blood brain barrier and demyelination. MMP-9 is increased in the cerebrospinal fluid of MS patients and expressed in MS lesions, indicating an involvement in MS pathogenesis. It is known that activated microglia secrete MMP. Modulation of MMP may thus be of interest for treatment in particular since MMP knock-out mice are less susceptible to experimental allergic encephalomyelitis. In this study we show that intact polyclonal immunoglobulins for intravenous use (IVIg) lead to increased secretion of MMP-9 in unstimulated microglia whereas F(ab')(2) fragments or stimulation with lipopolysaccharide (LPS) had no effect on MMP production at all. We could not detect MMP-2, MMP-3, MMP-7, MMP-10, MMP-11, and MMP-12 by RT-PCR with and without stimulation with LPS. IVIg differentially modulate MMP-9 production in resting and activated microglia suggesting an activation-dependent immune response.