Nobutaka Eiraku

An autoaggressive process against bystander tissues in HTLV-I-infected individuals : a possible pathomechanism of HAM/TSP

Human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a well-defined clinico-pathological entity in which the virus infection and the host immune responses are involved in the pathomechanism. It is generally agreed that the virus infection precedes the development of HAM/TSP and the infection is persistent during the course of disease. However, what plays the key role for the development of HAM/TSP remains to be elucidated. In this article, we emphasise the importance of the unique nature of HTLV-I-infected cells, which may have a potential ability to produce viral antigens outside of the blood flow, and we also review a variety of evidences supporting the following proposal. In our hypothesis, the supply of infected T cells from blood flow to central nervous system (CNS) is primary for the development of CNS lesions. Both anatomically determined hemodynamic conditions and adhesion molecule-mediated interactions between circulating infected T cells and endothelial cells may contribute to the localization of the main lesions. Following an induction of the HTLV-I antigens on the surface of infected T cells in CNS compartment, expansion of the responses of immunocompetent T cells against the viral proteins may result in CNS tissue damage which may be mediated by released cytokines. This is the first attempt to implicate a bystander damage mechanism in a human disease as an essential pathomechanism.

Elevated levels of interleukin-6 in serum and cerebrospinal fluid of HTLV-I-associated myelopathy/tropical spastic paraparesis

A significant elevation of interleukin-6 (IL-6) level was observed both in serum (mean 0.455 +/- 0.251) and in cerebrospinal fluid (CSF) (mean 0.043 +/- 0.016) obtained from 13 patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) when compared to that of either asymptomatic carriers (mean 0.181 +/- 0.074 and 0.021 +/- 0.015, respectively) or controls (mean 0.208 +/- 0.119 and 0.021 +/- 0.015, respectively). The differences were statistically significant between HAM/TSP and asymptomatic carrier for serum (P less than 0.05) or CSF (P less than 0.01). The correlation indexes between serum IL-6 and anti-HTLV-I antibody titers in serum and CSF were 0.61 (P less than 0.06) and 0.67 (P less than 0.05), respectively. Both the cell count and protein level in CSF correlated with CSF IL-6 activity at 0.68 (P less than 0.01) and 0.56 (P less than 0.05), respectively. The results demonstrate that IL-6 may contribute to the production of anti-HTLV-I antibody, and signs of slight inflammation are present in the central nervous system in HAM/TSP.

Association of AKT1 haplotype with the risk of schizophrenia in Iranian population.

AKT‐glycogen synthase kinase 3β (GSK3β) signaling is a target of lithium and has been implicated in the pathogenesis of mood disorders and schizophrenia. AKT1 protein level is decreased in the peripheral lymphocytes and brains of schizophrenic patients. The SNP2/3/4 TCG haplotype of AKT1 was associated with schizophrenia in patients with Northern European origin. In the present study, we genotyped five single nucleotide polymorphisms (SNP1–5) of AKT1 gene according to the original study in Iranians comprising of 321 schizophrenic patients and 383 controls, all residing in Mashhad city, Northeastern Iran. Haplotype analysis showed that the frequency of a five‐SNP haplotype (AGCAG) was significantly higher in schizophrenic patients (0.068) than that of controls (0.034) (P = 0.03 after Bonferroni correction, OR = 2.04, CI = 1.2–3.4). In stratified analysis by schizophrenia subtypes, the frequency of the same haplotype was significantly higher in disorganized subtype (n = 78, frequency of haplotype=0.081) when compared with normal controls (P = 0.04 after Bonferroni correction, OR = 2.59, CI = 1.3–5.2). Our findings did not confirm the association of AKT1 SNP2/3/4 TCG haplotype with the risk of schizophrenia as reported in the original study but showed the evidence of association with a different haplotype, AKT1 five‐SNP AGCAG haplotype, with the risk of schizophrenia in Iranian population.

Evidence of immunostimulating lipoprotein existing in the natural lipoteichoic acid fraction

ABSTRACT Lipoteichoic acid (LTA) is a cell surface glycoconjugate of gram-positive bacteria and is reported to activate the innate immune system. We previously reported that purified LTA obtained from Enterococcus hirae has no immunostimulating activity, but a subfraction (Eh-AF) in an LTA fraction possesses activity. In this study, we established a mouse monoclonal antibody neutralizing the activity of Eh-AF and investigated its inhibitory effects. Monoclonal antibody (MAbEh1) was established by the immunization of BALB/c mice with Eh-AF, followed by hybridoma screening based on its inhibitory effect for the production of interleukin-6 (IL-6) induced by Eh-AF. MAbEh1 neutralized the production of IL-6 by LTA fraction from not only E. hirae but also Staphylococcus aureus, while it failed to block that of lipopolysaccharide, suggesting that the antibody recognized a common active structure(s) in LTA fractions. Synthetic glycolipids in these LTAs did not induce cytokine production, at least in our system. Interestingly, the antibody was found to inhibit the activity of immunostimulating synthetic lipopeptides, Pam3CSK4 and FSL-1. These results suggest that MAbEh1 neutralizes the activity of lipoprotein-like compounds which is responsible for the activity of the LTA fraction of E. hirae and S. aureus.

Decreased Human T Lymphotropic Virus Type I (HTLV-I) Provirus Load and Alteration in T Cell Phenotype after Interferon-α Therapy for HTLV-I–Associated Myelopathy/Tropical Spastic Paraparesis

To analyze the mechanism by which interferon (IFN)-alpha is effective against human T cell lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP), we investigated the T cell phenotype and HTLV-I provirus load in peripheral blood mononuclear cells from 25 patients with HAM/TSP that were obtained before and after administration of IFN-alpha. The frequency of memory (CD45RA(-)CD27(+)) T cells that were CD8(high+), CXCR3(+) cell populations, and HTLV-I provirus loads were significantly decreased after treatment. The proportion of memory T cells in the CD8(high+) cell population correlated well with HTLV-I provirus load, whereas the proportion of effector (CD45RA(+)CD27(-)) cells in the CD8(high+) cell population was inversely correlated with provirus load. Interestingly, the frequency of perforin expression in CD8(high+) cells was significantly decreased after treatment in patients who experienced clinical improvement, whereas patients who did not experience clinical improvement showed an increased frequency of perforin expression. Our data suggest that fluctuations in these cell subsets are associated with both the immunomodulatory effect of IFN-alpha and the observed clinical benefit of IFN-alpha treatment in patients with HAM/TSP.

Activated T lymphocytes in cerebrospinal fluid of patients with HTLV-I-associated myelopathy (HAM/TSP)

In order to detect activated T lymphocytes in the cerebrospinal fluid (CSF) of patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP), we studied CSF lymphocytes in untreated patients with HAM/TSP and other neurological diseases (OND). Dual-immunofluorescence staining technique was performed using fluorescence microscopy. No significant difference in the CD4+/CD8+ ratio of CSF lymphocytes was observed between HAM/TSP patients and patients with OND. However, both CD4+ and CD8+ CSF lymphocytes of HAM/TSP patients contained higher percentages of HLA-DR-positive cells than those of patients with OND (P less than 0.05), suggesting that the activated CSF T lymphocytes were composed of both CD4+ and CD8+ subsets in patients with HAM/TSP.

In vitro modulation of lymphocyte proliferation by prednisolone and interferon-α in patients with HTLV-I-associated myelopathy (HAM)

One of the hallmarks of human T-lymphotropic virus type I (HTLV-I) infection is the proliferation in vitro of peripheral blood lymphocytes (PBLs) in the absence of growth factors. This phenomenon, the autologous proliferative response (APR), involves spontaneous growth of HTLV-I-infected T-cells and proliferation of T-cells in response to the infected cells. We studied the modulating effect of prednisolone (PSL) and interferon-alpha (IFN) on APR of PBLs obtained from five patients with HTLV-I-associated myelopathy (HAM). APR was significantly inhibited by PSL and IFN suggesting that APR is important in the pathogenesis of HAM.

Cell surface phenotype of in vitro proliferating lymphocytes in HTLV-I-associated myelopathy (HAM/TSP)

The in vitro proliferation of peripheral blood lymphocytes (PBLs) without any mitogenic stimulation is one of the hallmarks of human T lymphotropic virus type I (HTLV-I) infection. Recent evidence suggests a difference in the degree of the phenomenon between HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and asymptomatic HTLV-I carriers (AC). In this article, we demonstrated several alterations in the features of the in vitro transformed lymphocytes between patients with HAM/TSP (n = 16) and AC (n = 8). The percentages of total CD8+ and CD8+CD28+ cells were significantly increased in the in vitro proliferating T lymphocytes derived from the patients with HAM/TSP when compared to those from AC. HAM/TSP was segregated from AC by the high degree of the proliferation of CD8+CD28+ cells. The expression of HTLV-I-specific antigens on the cultured PBLs was detected only in the subjects which showed low CD8+CD28+/CD4+ ratio of the in vitro proliferating lymphocytes. These findings suggest that this phenomenon distinguishes HAM/TSP from AC, not only in quantity but also in quality.

ApaI polymorphism of vitamin D receptor gene is associated with susceptibility to HTLV-1-associated myelopathy/tropical spastic paraparesis in HTLV-1 infected individuals

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is one outcome of human T-cell lymphotropic virus type-1 (HTLV-1) infection. It remains unknown why the majority of infected people remain healthy, whereas only approximately 2-3% of infected individuals develop the disease. The active form of vitamin D has immunomodulatory effects, and allelic variants of the vitamin D receptor (VDR) appear to be associated with differential susceptibility to several infectious diseases. To investigate whether VDR single nucleotide polymorphisms (SNPs) are associated with the development of HAM/TSP, we studied four VDR SNPs in a group of 207 HAM/TSP patients and 224 asymptomatic HTLV-1 seropositive carriers (HCs) in Kagoshima, Japan, by using PCR-RFLP analysis. We found that ApaI polymorphism of VDR is associated with the risk of HAM/TSP, although this polymorphism did not affect the provirus load of HTLV-1 in either HAM/TSP patients or HCs.

Human T-cell lymphotropic virus type I (HTLV-I)-related clinical and laboratory findings for HTLV-I-infected blood donors.

Clinical and laboratory findings were examined for 111 human T-cell lymphotropic virus type I (HTLV-I)-infected blood donors. HTLV-I provirus loads in subjects with a family history of adult T-cell leukemia (ATL) or HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) tended to be higher than those in subjects without a family history of these conditions. There were 3 asymptomatic patients with ATL, 4 with a history of uveitis, 7 with hyperreflexia in the lower limbs, and 3 with urinary frequency in the night. The mean CD4 cell/CD8 cell ratio +/- SD was significantly lower (p<.0001) in subjects with hyperreflexia in the lower limbs (1.3 +/- 0.2) than in subjects without any clinical abnormalities (1.7 +/- 0.6), suggesting that subjects with hyperreflexia in the lower limbs already have some immunologic abnormalities. The concordance of HTLV-I infection between husband and wife was lower in this study than in a previous study. HTLV-I-related inflammatory symptoms were more frequent (p =.021, Fisher exact test; OR = 9.5; 95% CI, 1.7-53.5) in HTLV-I tax A-infected donors (3 [50%] of 6 donors) than in HTLV-I tax B-infected donors (10 [9.5%] of 105 donors), suggesting different risks of HTLV-I-related symptoms according to the virus genotype.