Central role of JC virus-specific CD4+ lymphocytes in progressive multi-focal leucoencephalopathy-immune reconstitution inflammatory syndrome

Abstract

Progressive multi-focal leucoencephalopathy and progressive multi-focal leucoencephalopathy-immune reconstitution inflammatory syndrome are caused by infection of the central nervous system with the JC polyoma virus. Both are complications of monoclonal antibody therapy in multiple sclerosis and other autoimmune diseases. Progressive multi-focal leucoencephalopathy-immune reconstitution inflammatory syndrome can obscure the diagnosis of progressive multi-focal leucoencephalopathy and lead to severe clinical disability and possibly death. Different from progressive multi-focal leucoencephalopathy, in which demyelination results from oligodendrocyte lysis by JC virus in the absence of an immune response, tissue destruction in progressive multi-focal leucoencephalopathy-immune reconstitution inflammatory syndrome is caused by a vigorous immune response within the brain. The cells and mediators that are involved in progressive multi-focal leucoencephalopathy-immune reconstitution inflammatory syndrome are as yet poorly understood. We examined two patients with multiple sclerosis, who developed progressive multi-focal leucoencephalopathy and later progressive multi-focal leucoencephalopathy-immune reconstitution inflammatory syndrome under natalizumab therapy. Due to initially negative JC viral deoxyribonucleic acid testing in the cerebrospinal fluid, a diagnostic brain biopsy was performed in one patient. Histopathology revealed brain inflammation characterized by a prominent T cell infiltrate (CD4(+)> CD8(+) T cells), but also B/plasma cells and monocytes. Despite very low JC viral load, both patients showed high intrathecal anti-JC virus antibodies. Brain-infiltrating CD4(+) T cells were studied regarding antigen specificity and function. CD4(+) T cells were highly specific for peptides from several JC virus proteins, particularly the major capsid protein VP1. T cell phenotyping revealed CD4(+) Th1 and bifunctional Th1-2 cells. The latter secrete large amounts of interferon-γ and interleukin-4 explaining the strong brain inflammation, presence of plasma cells and secretion of intrathecal anti-VP1 antibodies. The functional phenotype of brain-infiltrating JC virus-specific CD4(+) T cells was confirmed and extended by examining brain-derived JC virus-specific CD4(+) T cell clones. Our data provide novel insight into the pathogenesis of progressive multi-focal leucoencephalopathy-immune reconstitution inflammatory syndrome and indicate that JC virus-specific CD4(+) T cells play an important role in both eliminating JC virus from the brain, but also in causing the massive inflammation with often fatal outcome.

TCR Bias and HLA Cross-Restriction Are Strategies of Human Brain-Infiltrating JC Virus-Specific CD4+ T Cells during Viral Infection

“…In a previous study, we reported the ability of some VP1-specific CD4 + T cells to secrete simultaneously IFN-g and IL-4, which we termed a Th1-2 phenotype (36). Cytokine release by the 14 braininfiltrating, VP1-specific CD4 + TCCs after in vitro stimulation with specific peptide was determined by ELISA (Fig.…”

“…In a previous study, we had established-from an MS patient who had developed PML-IRIS under natalizumab treatment-several brain-infiltrating, JCV-specific CD4 + TCCs that recognized different peptides of the major capsid protein of JCV, VP1 (36). Toward this aim, brain-derived, PHA-expanded mononuclear cells were seeded with autologous PBMCs and VP1 protein.…”

“…The fine specificity of these 14 TCCs was determined using overlapping peptides spanning the VP1 sequence (36) (Supplemental Table I). All TCCs recognized only one VP1 peptide with the exception of TCC-7, which recognized three peptides that differ in a single amino acid and represent common mutations of the same amino acid sequence (36). Five TCCs (TCCs 1-5) were specific for peptide VP1 34 (the number denotes the first amino acid).…”

“…Our results demonstrated that JCV-specific CD4 + T cells with Th1 and Th1-2 phenotype are probably the most critical element among the CNS-infiltrating T and B cells. IFN-g released by JCV-specific CD4 + T cells is most likely responsible for the proinflammatory state in the CNS with macrophage activation, upregulation of HLA class II, and efficient Ag presentation, whereas IL-4 leads to the activation and expansion of memory B cells/plasmablasts and intrathecal production of virus-specific Abs (36).…”

“…Brain-infiltrating, VP1-specific TCCs were generated as previously described (36). Briefly, brain tissue from an relapsing remitting-MS patient, who developed PML-IRIS under natalizumab treatment and who expressed the HLA class II molecules DRB1*11:03, DRB1*15:01, DRB3*02:02, DRB5*01:01, DQA1*01:02, DQA1*05, DQB1*03:01, and DQB1*06:02, was cut into small pieces and disrupted by incubation in a solution containing 1 mg/ml collagenase A (Roche Diagnostics, Penzberg, Germany) and 0.1 mg/ml DNase I (Roche).…”