Shinji Ijichi

HTLV-I-associated myelopathy: analysis of 213 patients based on clinical features and laboratory findings

We studied the clinical features and laboratory findings in 213 patients with HTLV-I-associated myelopathy/tropical spastic paraparesis as diagnosed in Kagoshima University Hospital. Some aspects of clinical features in HTLV-I-associated myelopathy/tropical spastic paraparesis were characterized by mode of HTLV-I transmission and age of onset. The patients with onset after 15 years old and no history of blood transfusion before the onset of the disease (151 patients, group I) showed a shorter interval between the time of disease onset and that of inability to walk. The patients with onset before 15 years old and without history of blood transfusion (21 patients, group II) had short stature and slow progression of the disease. The interval time and the progression of the disease in patients with history of blood transfusion before onset of disease (41 patients, group III) were in between those of the above two groups. Patients whose ages of onset were older than 61 years old showed a faster progression than those with younger onset regardless of the mode of HTLV-I transmission. HTLV-I-associated myelopathy/tropical spastic paraparesis patients often also showed other organ disorders such as leukoencephalopathy (69%), abnormal findings on chest X-ray (50%), Sjögren syndrome (25%) and arthropathy (17%). The patients with low anti-HTLV-I antibody titers in the cerebrospinal fluid (2X-8X by PA method) had an older age of onset on average, milder clinical symptoms and lesser increase of neopterin in the cerebrospinal fluid than those in the high titer subgroup whose titers were higher than 1024X in cerebrospinal fluid regardless of the mode of HTLV-I transmission. We speculate that the clinical course of HTLV-I-associated myelopathy/tropical spastic paraparesis mainly shows a slow progression which consists of an initial progressive phase (probably an inflammatory phase) and a latter chronic phase, although some patients showed acute/subacute onset and rapid progression.

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.

HTLV-I proviral DNA amount correlates with infiltrating CD4+ lymphocytes in the spinal cord from patients with HTLV-I-associated myelopathy

A quantitative method utilizing polymerase chain reaction was employed to evaluate the amount of human T-cell leukemia virus type I (HTLV-I) proviral DNA in the affected spinal cords from patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Central nervous system (CNS) tissues were obtained at post-mortem from five patients with HAM/TSP, who vary in the duration of illness from 2.5-10 years, and one patient with adult T-cell leukemia (ATL), who had leukemic cell infiltration in the CNS. The presence of HTLV-I pX and pol sequences in the CNS tissues were demonstrated in all patients examined. In HAM/TSP, the proviral DNA quantified in the thoracic cord was 0.002-2 copies per 100 tissue cells, and that in the peripheral blood mononuclear cells (PBMC) was 2-8 copies per 100 PBMC. The proviral DNA amount in the thoracic cord of the patient with ATL was 0.4 copies per 100 tissue cells. An apparent propensity for the amount of integrated HTLV-I in the thoracic cord to decrease with the disease duration in patients with HAM/TSP was observed. The decline in HTLV-I proviral DNA amount in the thoracic cord lesions was paralleled with the alteration of proportion of CD4+ T lymphocytes in patients with HAM/TSP. These findings suggest that preferential virus reservoir may be infiltrating CD4+ T lymphocytes in the spinal cord lesions of patients with HAM/TSP, and HTLV-I infection in the CNS of patients is declining with the disease duration in spite of the chronic course of neurological manifestations at least in some patients with HAM/TSP.

Apoptosis of T Lymphocytes in the Spinal Cord Lesions in HTLV-I-Associated Myelopathy: A Possible Mechanism to Control Viral Infection in the Central Nervous System

Abstract. Immunocytochemical staining of spinal cords from five autopsied patients with HAM/TSP was performed using the monoclonal antibody TIA-1, a marker of cytotoxic T lymphocytes (CTL). Many TIA-1+, CD8+ cells are distributed in active inflammatory lesions. The number of TIA-1 + cells is related to the amount of HTLV-I proviral DNA in situ. The protein TIA-1 has been associated with the induction of apoptosis in target cells. In active inflammatory lesions, we found cells undergoing apoptosis, most of them identified as helper-inducer CD45RO T lymphocytes, which were consistent with in vivo cellular tropism of HTLV-I in patients with HAM/TSP. These findings suggest that CTL-induced apoptosis of T lymphocytes may be one of the possible mechanisms which eliminate HTLV-I-infected cells from the central nervous system. In addition, many T lymphocytes in the inflammatory lesions expressed bcl-2 oncoprotein, suggesting that infiltrated T lymphocytes may be resistant to apoptosis. Expression of bcl-2 oncoprotein may explain the longstanding inflammatory process in the central nervous system of 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.

Diversity of intrathecal antibody synthesis against HTLV-I and its relation to HTLV-I associated myelopathy

The humoral immune response against human T-cell lymphotropic virus type I (HTLV-I) in the central nervous system (CNS) compartment and in the blood was investigated by enzyme immunoassay using 16 synthetic peptides corresponding to HTLV-I core and envelope sequences. We evaluated paired samples of cerebrospinal fluid and serum from HTLV-I seropositive Japanese patients, classified as follows: HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP;n = 39), patients with spinal cord disease ascribed to either HAM/TSP or to some concomitant, HTLV-I-unrelated disease (possible HAM/TSP;n = 6) or carriers without any clinical signs of HAM/TSP (n = 15). HTLV-I-peptide-specific intrathecal antibody synthesis was found in 79% of HAM/TSP patients, but only in 20% of carriers without HAM/TSP. The group of carriers without HAM/TSP showed local synthesis for some peptides (on average 0.3 peptides per patient). In most HAM/TSP patients, however, there was a diverse intrathecal immune response to several HTLV-I synthetic peptides (on average against 3.6 peptides per HAM/TSP patient), most frequently againstgag p19 100–130,env gp21 458–488, andenv gp46 175–199 and 288–317. The intrathecal antibody synthesis against several HTLV-I determinants may represent a pathogenic immune response in HAM/TSP and is possibly related to the infiltration of virus-infected T-cells in the spinal cord.

HAM/TSP : Recent perspectives in Japan

Neurologic diseases associated with human T-cell lymphotropic virus type I (HTLV-I) infection have a clinical spectrum that includes myelopathy (HTLV-I-associated myelopathy/tropical spastic paraparesis, HAM/TSP) as the central manifestation. Many clinical signs of involvement outside the central nervous system (CNS) have been described in some patients with HAM/TSP and have triggered and advanced the discovery of some HTLV-I-associated concepts in HTLV-I-infected individuals without signs of CNS involvement. Most of these HTLV-I-associated diseases exhibit common viroimmunologic characteristics that include a distributional bias of HTLV-I activation between the blood flow and the affected lesions and accumulated cellular immune responses in the lesions. These facts suggest that the vulnerable tissue(s) in some HTLV-I-infected individuals may not be defined by an exclusive tissue specificity, but that common steps of HTLV-I-versus-host interactions may have an important role in the pathologic process(es) in these diseases. This review summarizes the recent perspectives of the clinical spectrum and the pathogenesis of HAM/TSP in Japan. Furthermore, the feasible pathogenic involvement of cellular interactions between infected cells and responding immunocompetent cells in the affected tissues is emphasized.

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.

Anti-viral and immunomodulatory effects of interferon-α on cultured lymphocytes from patients with human T lymphotropic virus type I-associated myelopathy (HAM/TSP)

In contrast to therapeutic benefits of interferon-alpha (IFN-alpha) in patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP), little is known about the mechanisms underlying its clinical efficacy. To investigate the anti-viral and/or immunomodulatory properties of IFN-alpha in HTLV-I infection, the effects of IFN-alpha on HTLV-I-induced in vitro phenomena were evaluated. In vitro activation of HTLV-I in fractionated CD4+ T lymphocyte-rich cells (CD4+ cells) could be demonstrated by increased thymidine incorporation into the cells, detection of proviral HTLV-I and viral RNA, and by assays of reverse transcriptase activities in culture supernatants. T cell immune responses were evaluated by thymidine incorporation into CD8+ T lymphocyte-rich cells (CD8+ cells) responding to cultured and irradiated autologous CD4+ cells possessing HTLV-I antigens. It could be shown that IFN-alpha suppressed both the in vitro activation of HTLV-I and the CD8+ cell response. Moreover, 1 day supplementation of IFN-alpha as a pretreatment was sufficient for the induction of these properties. These findings, together with the clinical efficacy of IFN-alpha administration in patients with HAM/TSP, support the view that viral activation and T cell responses are critical components in the pathogenic processes involved in HAM/TSP.