There is growing evidence that GVHD affects the central nervous system (CNS). In this study, we describe the long-term follow-up of four allogeneic BM recipients who developed cerebral angiitis-like disease probably due to GVHD. The patients developed focal neurological signs, cognitive deficits and/or coma in association with GVHD, 2-18 years after transplantation, following reduction of immunosuppressive therapy. Magnetic resonance imaging was variable, showing generalized brain atrophy, ischemic lesions or leukoencephalopathy. Diagnosis of cerebral angiitis was confirmed by histopathological analysis of bioptic brain tissue and response to immunosuppressive therapy. By means of immunohistochemistry and immunofluorescence, perivascular lymphomononuclear cerebral infiltrates were shown to express the adhesion receptor, CD11a, and the chemokine receptor, CCR5. Our findings imply that GVHD should be considered in the differential diagnosis of noninfectious angiitis-like disease of the CNS in long-term survivors after allogeneic BMT. Infiltrating cells, in analogy to typical target organs of GVHD such as skin or liver, expressed CD11a and CCR5. These findings could be of etiopathological, diagnostic and therapeutic relevance.Bone Marrow Transplantation advance online publication, 16 November 2009; doi:10.1038/bmt.2009.323.

Herpes simplex virus type 1 (HSV-1) latent persistence in human trigeminal ganglia (TG) is accompanied by a chronic CD8 T-cell infiltration. Thus far, during HSV-1 latency only a single transcript, namely the latency-associated transcript (LAT), has been identified to be synthesized but not translated into a protein. In contrast, the chronic CD8 T-cell infiltration suggests that an antigen trigger must be present. The focus of the current work was to look for HSV-1 transcription activity as a potential trigger of the immune response and to demonstrate whether the immune cells are clonally expanded and have a phenotype that suggests that they have been triggered by viral antigen. By combining in situ hybridization, laser cutting microscopy, and single-cell real time RT-PCR, we demonstrated expression of the HSV-1 immediate early (IE) genes ICP0 and ICP4 in human trigeminal neurons. Using CDR3 spectratyping, we showed that the infiltrating T cells are clonally expanded, indicating an antigen-driven immune response. Moreover, the persisting CD8(+) T cells had prominent features of the memory effector phenotype. Chemokines CCL5 and CXCL10 were expressed by a subpopulation of infiltrating cells and the corresponding chemokine receptors CCR5 and CXCR3 were co-expressed on virtually all T cells bearing the CD8 phenotype. Thus, HSV-1 IE genes are expressed in human TG, and the infiltrating T cells bear several characteristics that suggest viral antigenic stimulation.

Following primary infection of the mouth, HSV-1 travels retrogradely along the maxillary (V2) or mandibular (V3) nerve to the trigeminal ganglion (TG), where it establishes lifelong latency. Symptomatic HSV-1 reactivations frequently manifest as herpes labialis, while ocular HSV-1 disease is rare. We investigated whether these clinical observations are mirrored by the distribution of latent HSV-1 as well as cytotoxic T-cell infiltration around the nerve cell bodies and in the nerve fibers. The three divisions of the TG were separated by using neurofilament staining and Di-I tracing and then screened by in-situ hybridization for the presence of HSV-1 latency- associated transcript (LAT). The T-cell distribution and the pattern of cytolytic molecule expression were evaluated by immunohistochemistry. The Di-I-labeled neurons were largely confined to the nerve entry zone of the traced nerve branches. Very few Di-I-labeled neurons were found in adjacent divisions due to traversing fiber bundles. LAT was abundant in the V2 and V3 divisions of all TGs, but scarce or totally absent in V1. CD8+ T-cells were found in all three divisions of the TGs and in the respective nerves, clearly clustering in V2 and V3, which is indicative of a chronic inflammation. Only T-cells surrounding neurons in the V2 and V3 ganglionic divisions expressed granzyme B. In conclusion, the large accumulation of LAT and cytotoxic T-cells in the V2 and V3 but not in the V1 division of the TG reflects the sites supplied by the sensory fibers and the clinical reactivation patterns.

Relapsing-remitting experimental autoimmune encephalomyelitis (EAE), a multiple sclerosis model, is induced in mice by injection of myelin proteolipid protein (PLP) encephalitogenic peptide, PLP(139-151), in adjuvant. In this study, prior to EAE induction, mice were vaccinated with a bacterial plasmid encoding a PLP-ubiquitin fusion (pCMVUPLP). During the relapse phase of EAE, clinical signs, histopathologic changes, in vitro lymphoproliferation to PLP(139-151) and interferon-gamma levels were reduced in pCMVUPLP-vaccinated mice, compared to mock-vaccinated mice (controls). Lymphocytes from pCMVUPLP-vaccinated mice produced interleukin-4, a cytokine lacking in controls. Thus, pCMVUPLP vaccination can modulate the relapse after EAE induction.

Human herpesvirus 6 (HHV-6) persists in the central nervous system, but its prevalence in the peripheral nervous system, a preferred latency site for herpesviruses, has not been studied. Using nested polymerase chain reaction (PCR), the authors determined the distribution of HHV-6 in human sensory ganglia. HHV-6 was present in 30% of trigeminal, 40% of geniculate, 25% of vestibular, and 55% of dorsal root ganglia. It co-occurred with alpha-herpesviruses (herpes simplex virus type 1 or varicella-zoster virus) in 91% of the ganglia. As HHV-6 positivity did not depend on the presence of inflammatory cells, known to harbor the virus, HHV-6 probably resides in the ganglia themselves.

CCL19 and CCL21 bind to CCR7, which is crucial for both inducing an immune response and establishing immunological tolerance. We report that in the normal human brain CCL19, but not CCL21, is transcribed, and detectable as a protein in tissue lysates and in cerebrospinal fluid. In both active and inactive multiple sclerosis (MS) lesions CCL19 transcripts were elevated. In cerebrospinal fluid from MS and OIND patients CCL19 protein was increased. In relapsing-remitting and secondary progressive MS patients CCL19 correlated with intrathecal IgG production. This study suggests that CCL19 plays a role in both the physiological immunosurveillance of the healthy CNS and the pathological maintenance of immune cells in the CNS of MS patients.

The latent persistence of herpes simplex virus type 1 (HSV-1) in human trigeminal ganglia (TG) is accompanied by a chronic CD8 T-cell infiltrate. The focus of the current work was to look for HSV-1 transcription activity as a potential trigger of the immune response and to characterize the immune cell infiltrates by this feature. We combined in situ hybridization, laser cutting microscopy, and single cell RT-PCR to demonstrate the expression of the HSV-1 immediate early (IE) genes ICP0 and ICP4 in human trigeminal neurons. Using CDR3 spectratyping, we showed that the infiltrating T-cells are clonally expanded, indicating an antigen-driven immune response. Moreover, the persisting CD8+ T-cells had features of the memory effector phenotype. The voltage-gated potassium channel Kv1.3, a marker of chronic activated memory effector cells, and the chemokines CCL5 and CXCL10 were expressed by a subpopulation of infiltrating cells. The corresponding chemokine receptors CCR5 and CXCR3 were co-expressed on virtually all CD8 T-cells. In addition, T-cells expressed granzymes and perforin. In contrast to animal models of HSV-1 latency, hardly any FoxP3-positive regulatory T-cells were detected in human TG. Thus, HSV-1 IE genes are expressed in human TG and the infiltrating T-cells bear several characteristics that suggest viral antigenic stimulation.

Animal studies suggest that adult bone marrow cells have the potential to migrate into the brain and generate new neural cells. Because data on this physiologic repair mechanism in humans are lacking, we investigated bone marrow engraftment into the brain of bone marrow recipients after sex-mismatched transplantation. Brain sections of seven allogeneic female bone marrow recipients were examined. The Y-chromosome, which served as a natural marker of donor bone marrow-derived cells after male-to-female transplantation, was identified by in situ hybridization. The neural phenotype of Y-chromosome-positive cells was determined using neural nuclear protein (NeuN) immunohistochemistry. Y-chromosome-positive cells expressing NeuN were found within the first 3 months after transplantation in both the cerebrum and the cerebellum at a frequency of 0.003% to 0.013% of all neurons. These cells were observed only in patients with cerebral lymphocytic infiltration and graft-versus-host disease. Our data suggest that adult bone marrow cells are capable of generating cells that express the neural marker NeuN early after transplantation. Cells with this specific phenotype may contribute to tissue repair in brain regions remote from neurogenic zones.

We examined 103 patients with vestibular neuritis (VN) in a follow-up study (5.7 to 20.5 years, mean 9.8 years). Two patients (1.9%) had developed a second occurrence of VN 29 to 39 months after the first. VN affected the contralateral ear in both and caused less severe distressing vertigo and postural imbalance. Unlike Bell's palsy and sudden hearing loss, a relapse in the same ear did not occur.