Masao Ogata

Human T-cell leukemia virus type I (HTLV-1) proviral load and disease progression in asymptomatic HTLV-1 carriers: a nationwide prospective study in Japan

Definitive risk factors for the development of adult T-cell leukemia (ATL) among asymptomatic human T-cell leukemia virus type I (HTLV-1) carriers remain unclear. Recently, HTLV-1 proviral loads have been evaluated as important predictors of ATL, but a few small prospective studies have been conducted. We prospectively evaluated 1218 asymptomatic HTLV-1 carriers (426 males and 792 females) who were enrolled during 2002 to 2008. The proviral load at enrollment was significantly higher in males than females (median, 2.10 vs 1.39 copies/100 peripheral blood mononuclear cells [PBMCs]; P < .001), in those 40 to 49 and 50 to 59 years of age than that of those 40 years of age and younger (P = .02 and .007, respectively), and in those with a family history of ATL than those without the history (median, 2.32 vs 1.33 copies/100 PBMCs; P = .005). During follow-up, 14 participants progressed to overt ATL. Their baseline proviral load was high (range, 4.17-28.58 copies/100 PBMCs). None developed ATL among those with a baseline proviral load lower than approximately 4 copies. Multivariate Cox analyses indicated that not only a higher proviral load, advanced age, family history of ATL, and first opportunity for HTLV-1 testing during treatment for other diseases were independent risk factors for progression of ATL.

Human Herpesvirus 6 DNA in Plasma after Allogeneic Stem Cell Transplantation: Incidence and Clinical Significance

BACKGROUND Human herpesvirus 6 (HHV-6) is increasingly recognized as an opportunistic and potentially life-threatening pathogen in recipients of allogeneic stem cell transplants (SCTs). METHODS To clarify the incidence and clinical relevance of active HHV-6 infection, serial titers of plasma HHV-6 DNA were determined for 50 allogeneic SCT recipients, using real-time polymerase chain reaction. RESULTS HHV-6 DNA was detected in plasma from 24 patients (48%). HHV-6 DNA was most frequently apparent approximately 14-27 days after transplantation. An increased risk of a positive result for HHV-6 DNA was associated with transplantation from an allelic-mismatch donor (P = .02) and administration of steroids (P = .04). Steroid use was associated with high HHV-6 DNA loads (P = .02). High HHV-6 DNA loads were correlated with delayed platelet engraftment (P = .04). Among patients who had positive results for HHV-6 DNA, the HHV-6 DNA load was higher in plasma from those who developed limbic encephalitis (n = 4) (P < .0001). CONCLUSIONS Active HHV-6 infection is not rare in SCT recipients. SCT from allelic-mismatch donors is associated with increased risk of active HHV-6 infection. Steroid therapy is associated with not only increased incidence of infection but also accelerated viral replication. Development of limbic encephalitis is associated with high HHV-6 DNA load.

Plasma HHV-6 viral load-guided preemptive therapy against HHV-6 encephalopathy after allogeneic stem cell transplantation: a prospective evaluation

Human herpesvirus 6 (HHV-6) causes life-threatening encephalopathy in recipients of allogeneic SCT, but no consensus has been reached regarding appropriate preventive methods. This study evaluated a plasma HHV-6 viral load-guided preemptive approach against HHV-6-associated encephalopathy. Plasma real-time PCR assay was performed once a week. Among 29 patients, 19 developed positive plasma HHV-6 DNA. Median maximum plasma HHV-6 DNA was 4593.5 copies/ml plasma (range, 150.0–127 891.0 copies/ml plasma). In one of eight events with low-level HHV-6 DNA (defined as <1000 copies/ml plasma) and four of seven events with mid-level HHV-6 DNA (1000–9999.5 copies/ml plasma), HHV-6 loads in plasma subsequently continued increasing. Ganciclovir was administered against six of nine patients with high-level HHV-6 DNA (⩾10 000 copies/ml plasma). High-level HHV-6 DNA resolved similarly in both groups with or without ganciclovir therapy. Among the nine patients with high-level HHV-6 DNA two developed encephalopathy. As encephalopathy developed before the detection of high-level HHV-6 DNA in plasma, these two patients had not received preemptive ganciclovir therapy. In conclusion, our preemptive approach against HHV-6-associated encephalopathy cannot prevent all cases of HHV-6 encephalopathy in SCT recipients due to the dynamic kinetics of plasma HHV-6 viral load.

Correlations of HHV-6 viral load and plasma IL-6 concentration with HHV-6 encephalitis in allogeneic stem cell transplant recipients

This study investigated factors associated with the development of human herpesvirus (HHV)-6 encephalitis. Among 111 enrolled subjects, 12 patients developed central nervous system (CNS) dysfunction. CNS dysfunction in four patients was found to have no association with HHV-6. The remaining eight patients displayed HHV-6 encephalitis (n=3), limbic encephalitis (HHV-6 DNA in cerebrospinal fluid was not examined; n=3) or CNS dysfunction because of an unidentified cause (n=2). Real-time PCR showed CNS dysfunction in the latter eight patients, which developed concomitant with the appearance of high plasma levels of HHV-6 DNA (⩾104 copies/ml). Overall, eight of the 24 patients with high-level HHV-6 DNA developed CNS dysfunction, whereas no patients developed CNS dysfunction potentially associated with HHV-6 infection if peak HHV-6 DNA was <104 copies/ml. We next analyzed plasma concentrations of IL-6, IL-10 and tumor necrosis factor-α among patients who displayed high-level plasma HHV-6 DNA and found elevated IL-6 concentrations preceding HHV-6 infection in patients who developed CNS dysfunction. (Mean±s.d.: 865.7±1036.3 pg/ml in patients with CNS dysfunction; 56.5±192.9 pg/ml in others; P=0.01). These results suggest that high-level HHV-6 load is necessary for the development of HHV-6 encephalitis, and systemic inflammatory conditions before HHV-6 infection form the preparatory conditions for progression to encephalopathy.

Inhibition of the SDF-1α–CXCR4 axis by the CXCR4 antagonist AMD3100 suppresses the migration of cultured cells from ATL patients and murine lymphoblastoid cells from HTLV-I Tax transgenic mice

Adult T-cell leukemia (ATL) is a T-cell malignancy caused by human T lymphotropic virus type I, and presents as an aggressive leukemia with characteristic widespread leukemic cell infiltration into visceral organs and skin. The molecular mechanisms associated with leukemic cell infiltration are poorly understood. We have used mouse models of ATL to investigate the role of chemokines in this process. Transfer of splenic lymphomatous cells from transgenic to SCID mice reproduces a leukemia and lymphoma that is histologically identical to human disease. It could be shown that lymphomatous cells exhibit specific chemotactic activity in response to stromal cell-derived factor-1alpha (SDF-1alpha). Lymphomatous cells exhibited surface expression of CXCR4, the specific receptor of SDF-1alpha. AMD3100, a CXCR4 antagonist, was found to inhibit both SDF-1alpha-induced migration and phosphorylation of extracellular signal-related kinase 1/2. Investigation of cultured cells from human ATL patients revealed identical findings. Using the SCID mouse model, it could be demonstrated that AMD3100 inhibited infiltration of lymphomatous cells into liver and lung tissues in vivo. These results demonstrate the involvement of the SDF-1alpha/CXCR4 interaction as one mechanism of leukemic cell migration and this may provide a novel target as part of combination therapy for ATL.

Human herpesvirus-6 encephalitis after allogeneic hematopoietic cell transplantation: what we do and do not know.

Human herpesvirus-6 (HHV-6) encephalitis following allogeneic hematopoietic cell transplantation is a serious and often fatal complication accompanying reactivation of HHV-6B. Incidence varies among studies, but is reportedly 0–11.6% after bone marrow or PBSC transplantation and 4.9–21.4% after umbilical cord blood transplantation, typically around 2–6 weeks post transplant. Symptoms are characterized by memory loss, loss of consciousness and seizures. Magnetic resonance imaging (MRI) typically shows bilateral signal abnormalities in the limbic system. This complication is considered to represent acute encephalitis caused by direct virally induced damage to the central nervous system, but our understanding of the etiologies and pathogenesis is still limited. The mortality rate attributable to this pathology remains high, and survivors are often left with serious sequelae such as impaired memory and epilepsy. Despite the poor prognosis, no validated treatments or preventative measures have been established. Establishment of preventative strategies represents an important challenge. This article reviews the current knowledge of the clinical features, incidence, pathogenesis and treatment of HHV-6 encephalitis, and discusses issues needing clarification in the future to overcome this serious complication.

Real-Time PCR Assay Compared to Nested PCR and Antigenemia Assays for Detecting Cytomegalovirus Reactivation in Adult T-Cell Leukemia-Lymphoma Patients

ABSTRACT We analyzed the efficiency of the quantitative real-time PCR assay for cytomegalovirus (CMV) reactivation in adult T-cell leukemia-lymphoma (ATL) patients and compared the results with those obtained with qualitative nested PCR and antigenemia assays. The viral load obtained by the real-time PCR assay closely paralleled the number of antigen-positive cells obtained with the antigenemia assay. Real-time PCR revealed that a large number of DNA copies could be present even in samples assessed as negative or low in antigen-positive cells (0 to 10 antigen-positive cells/50,000 cells) by antigenemia assay. CMV copy numbers did not differ between the negative and low-antigen-positive groups. When the input concentration for real-time PCR assay was 2,500 to 5,000 copies/ml, the positivity rate for the nested PCR assay was 47.3%, while the positivity rate was more than 90% at an input concentration of ≥50,000 copies/ml. Real-time PCR is more sensitive than the antigenemia and nested PCR assays. Moreover, real-time PCR was able to detect CMV reactivation earlier than the antigenemia and nested PCR assays through the use of longitudinal analysis in four ATL patients with CMV pneumonia. In longitudinal assessments, analysis of the results suggested that a cutoff level of 5,000 copies/ml might be used to initiate treatment. Real-time PCR is more suitable for monitoring CMV reactivation in ATL patients than the antigenemia and nested PCR assays. CMV viral loads of 5,000 copies/ml are proposed as the cutoff for initiating antiviral therapy in ATL patients.

Eosinophilia associated with adult T-cell leukemia: role of interleukin 5 and granulocyte-macrophage colony-stimulating factor.

To clarify the mechanism of eosinophilia in adult T‐cell leukemia (ATL), we studied three ATL patients having marked eosinophilia. Eosinophil‐predominant colony‐stimulating activity was detected in the serum of one patient and in the conditioned media (CM) from cultured ATL cells from two patients. Soluble interleukin 5 (IL‐5), but no interleukin 3 (IL‐3) and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), was detected in sera from all patients. On the other hand, GM‐CSF was produced in vitro by ATL cells from all cases, whereas detectable IL‐3 and IL‐5 was produced by cells from only one, suggesting that in the other two cases, the serum IL‐5 was produced by the normal reacting lymphocytes. The fact that no patient showed marked neutrophilia supports the possibility that IL‐5 may have a leading role in the development of eosinophilia, with GM‐CSF produced by ATL cells playing a complementary role. Am. J. Hematol. 59:242–245, 1998.

High incidence of cytomegalovirus, human herpesvirus-6, and Epstein–Barr virus reactivation in patients receiving cytotoxic chemotherapy for Adult T cell leukemia

The etiology of cytomegalovirus (CMV), human herpesvirus‐6 (HHV‐6), and Epstein–Barr virus (EBV) reactivation and the potential for complications following cytotoxic chemotherapy in the absence of allogeneic transplantation are not clearly understood. Patients with adult T cell leukemia (ATL) are susceptible to opportunistic infections. In this study, the incidence, kinetics and clinical significance of reactivation of CMV, HHV‐6, and EBV in ATL patients were investigated. Viral DNA in a total of 468 plasma samples from 34 patients was quantified using real‐time PCR. The probability of CMV, HHV‐6, and EBV reactivation by 100 days after the start of chemotherapy was 50.6%, 52.3%, and 21.6%, respectively. Although most CMV reactivations were self‐limited, plasma CMV DNA tended to persist or increase if the CMV DNA levels in plasma reached ≥104 copies/ml. CMV reactivation was negatively associated with survival, but the P‐value for this association was near the borderline of statistical significance (P = 0.052). One patient developed fatal interstitial pneumonia concomitant with peak CMV DNA accumulation (1.6 × 106 copies/ml plasma). Most HHV‐6 and EBV reactivations were self‐limited, and no disease resulting from HHV‐6 or EBV was confirmed. HHV‐6 and EBV reactivation were not associated with reduced survival (P = 0.35 and 0.11, respectively). These findings demonstrated that subclinical reactivation of CMV, HHV‐6, and EBV were common in ATL patients receiving chemotherapy. There were differences in the viral reactivation patterns among the three viruses. A CMV load ≥104 copies/ml plasma was indicative of subsequent exacerbation of CMV reactivation and developing serious clinical course. J. Med. Virol. 83:702–709, 2011.

Successful bone marrow transplantation from an unrelated donor in a patient with adult T cell leukemia

We report a 51-year-old male with adult T cell leukemia (ATL) who received a BMT from an HLA-identical unrelated donor. The ATL proved refractory to chemotherapy, and he underwent BMT conditioned with CY/TBI. Complications of encephalitis of unknown origin were successfully treated with steroid therapy and the patient has been in CR for 16 months after BMT. Human T cell leukemia virus type 1 proviral DNA loads were reduced to undetectable levels in PBMC sampled 12 months after BMT. This encouraging result suggests that BMT from an unrelated donor should be considered for ATL even if the disease is refractory to chemotherapy.