Satellite glial cells in human trigeminal ganglia have a broad expression of functional Toll-like receptors.

Toll-like receptors (TLRs) orchestrate immune responses to a wide variety of danger- and pathogen-associated molecular patterns. Compared to the central nervous system (CNS), expression profile and function of TLRs in the human peripheral nervous system (PNS) are ill-defined. We analyzed TLR expression of satellite glial cells (SGCs) and microglia, glial cells predominantly involved in local immune responses in ganglia of the human PNS and normal-appearing white matter (NAWM) of the CNS, respectively. Ex vivo flow cytometry analysis of cell suspensions obtained from human cadaveric trigeminal ganglia (TG) and NAWM showed that both SGCs and microglia expressed TLR1-5, TLR7, and TLR9, although expression levels varied between these cell types. Immunohistochemistry confirmed expression of TLR1-TLR4 and TLR9 by SGCs in situ. Stimulation of TG- and NAWM-derived cell suspensions with ligands of TLR1-TLR6, but not TLR7 and TLR9, induced interleukin 6 (IL-6) secretion. We identified CD45LOW CD14POS SGCs and microglia, but not CD45HIGH leukocytes and CD45NEG cells as the main source of IL-6 and TNF-α upon stimulation with TLR3 and TLR5 ligands. In conclusion, human TG-resident SGCs express a broad panel of functional TLRs, suggesting their role in initiating and orchestrating inflammation to pathogens in human sensory ganglia.

Prevalence of Intrathecal Acyclovir Resistant Virus in Herpes Simplex Encephalitis Patients.

Herpes simplex encephalitis (HSE) is a life-threatening complication of herpes simplex virus (HSV) infection. Acyclovir (ACV) is the antiviral treatment of choice, but may lead to emergence of ACV-resistant (ACVR) HSV due to mutations in the viral UL23 gene encoding for the ACV-targeted thymidine kinase (TK) protein. Here, we determined the prevalence of intrathecal ACVR-associated HSV TK mutations in HSE patients and compared TK genotypes of sequential HSV isolates in paired cerebrospinal fluid (CSF) and blister fluid of mucosal HSV lesions. Clinical samples were obtained from 12 HSE patients, encompassing 4 HSV type 1 (HSV-1) and 8 HSV-2 encephalitis patients. HSV DNA load was determined by real-time PCR and complete HSV TK gene sequences were obtained by nested PCR followed by Sanger sequencing. All HSV-1 HSE patients contained viral TK mutations encompassing 30 unique nucleotide and 13 distinct amino acid mutations. By contrast, a total of 5 unique nucleotide and 4 distinct amino acid changes were detected in 7 of 8 HSV-2 patients. Detected mutations were identified as natural polymorphisms located in non-conserved HSV TK gene regions. ACV therapy did not induce the emergence of ACVR-associated HSV TK mutations in consecutive CSF and mucocutaneous samples of 5 individual patients. Phenotypic susceptibility analysis of these mucocutaneous HSV isolates demonstrated ACV-sensitive virus in 2 HSV-1 HSE patients, whereas in two HSV-2 HSE patients ACVR virus was detected in the absence of known ACVR-associated TK mutations. In conclusion, we did not detect intrathecal ACVR-associated TK mutations in HSV isolates obtained from 12 HSE patients.

Intrathecal CD8 T-cells of multiple sclerosis patients recognize lytic Epstein-Barr virus proteins.

BACKGROUND: The association between Epstein-Barr virus (EBV) and multiple sclerosis (MS) may involve intrathecal EBV-specific T-cell responses targeting the virus or indirectly, autoantigens. OBJECTIVE: Compare the prevalence and fine-specificity of EBV-specific T-cells in the cerebrospinal fluid (CSF) of patients with MS (n = 12), clinically-isolated syndrome (CIS) (n = 17) and other neurological diseases (OND) (n = 13). METHODS: Intrathecal EBV-specific T-cell reactivity was assayed using CSF-derived T-cell lines (CSF-TCL) and autologous EBV-transformed B-cells (autoBLCL) as antigen-presenting cells (APC). EBV proteins recognized by autoBLCL-specific CD8 T-cells were identified using human leukocyte antigen class I (HLA-I)-negative monkey cells as artificial APC, co-transfected with 59 different EBV genes and the corresponding patient's HLA-I alleles that were involved in autoBLCL T-cell reactivity. Reactivity towards the MS-associated autoantigen αB-crystallin (CRYAB) was determined analogously. RESULTS: CSF-TCL from CIS and MS patients had significantly higher frequencies of autoBLCL-reactive CD4 T-cells, compared to the OND patients. CIS patients also had significantly higher autoBLCL-reactive CD8 T cells, which correlated with reactive CD4 T-cell frequencies. AutoBLCL-specific CD8 T-cell responses of four CSF-TCL analyzed in detail were oligoclonal and directed to lytic EBV proteins, but not CRYAB endogenously expressed by autoBLCL. CONCLUSIONS: Enhanced intrathecal autoBLCL-specific T-cell reactivity, selectively directed towards lytic EBV proteins in two CSF-TCL, suggested a localized T-cell response to EBV in patients with MS. Our data warrant further characterization of the magnitude and breadth of intrathecal EBV-specific T-cell responses in larger patient cohorts.

Intrathecal CD4(+) and CD8(+) T-cell responses to endogenously synthesized candidate disease-associated human autoantigens in multiple sclerosis patients.

MS pathology is potentially orchestrated by autoreactive T cells, but the antigens recognized remain unknown. A novel APC/T-cell platform was developed to determine intrathecal CD4(+) and CD8(+) T-cell responses to candidate MS-associated autoantigens (cMSAg) in clinically isolated syndrome (CIS, n = 7) and MS (n = 6) patients. Human cMSAg encoding open reading frames (n = 8) were cloned into an Epstein-Barr virus (EBV)-based vector to express cMSAg at high levels in EBV-transformed B-cells (BLCLs). Human cMSAg cloned were myelin-associated and -oligodendrocyte glycoprotein, myelin basic protein, proteolipid protein, ATP-dependent potassium channel ATP-dependent inwards rectifying potassium channel 4.1, S100 calcium-binding protein B, contactin-2, and neurofascin. Transduced BLCLs were used as autologous APC in functional T-cell assays to determine cMSAg-specific T-cell frequencies in cerebrospinal fluid derived T-cell lines (CSF-TCLs) by intracellular IFN-γ flow cytometry. Whereas all CSF-TCL responded strongly to mitogenic stimulation, no substantial T-cell reactivity to cMSAg was observed. Contrastingly, measles virus fusion protein-specific CD4(+) and CD8(+) T-cell clones, used as control of the APC/T-cell platform, efficiently recognized transduced BLCL expressing their cognate antigen. The inability to detect substantial T-cell reactivity to eight human endogenously synthesized cMSAg in autologous APC do not support their role as prominent intrathecal T-cell target antigens in CIS and MS patients early after onset of disease.