Molecular and clinical effects of betamethasone in human T-cell lymphotropic virus type-I-associated myelopathy/tropical spastic paraparesis patients

There is no effective therapy for human T‐cell lymphotropic virus type I (HTLV‐I)‐associated myelopathy/tropical spastic paraparesis (HAM/TSP). Glucocorticoids are effective to reduce the motor disability in these patients, but its role as anti‐spastic drugs is unknown. Here it is reported the use of corticosteroids in HAM/TSP. The goal was to find reliable molecular markers linked to treatment effectiveness. The clinical efficacy of corticosteroids was studied in 22 HAM/TSP. The treatment was a single dose of 7.0 mg of systemic betamethasone. Pre‐treatment samples were obtained immediately before steroid administration and post‐treatment samples were collected after 5 days. Neurological disability was evaluated by the Osame's Motor Disability Scales. Relative levels of Tax, Foxp3, IL‐10, TGF‐β, CTLA‐4, and GITR mRNA were measured and the percentage of CD4⁺Foxp3⁺ and CD4⁺Tax⁺ populations was quantified in PBMCs by real‐time PCR and flow cytometry, respectively. The same parameters were studied in eight untreated carriers. Betamethasone treatment showed neurological improvement in 21 HAM/TSP patients, with one patient without response to treatment. This therapy was associated with a decrease in Tax mRNA load and CD4⁺Tax⁺ T cells in HAM/TSP. Simultaneously, an increase in Foxp3 mRNA and CD4⁺Foxp3⁺ T cell was detected in these patients. The other markers studied had no significant changes after treatment. Clinical improvement in betamethasone‐treated HAM/TSP was associated with an inverse relationship between a decrease in Tax and an increase in Foxp3 at the mRNA and protein levels. These results suggest that both Tax and Foxp3 may represent potential biomarkers for drug treatment assessments in HAM/TSP. J. Med. Virol. 83:1641–1649, 2011. © 2011 Wiley‐Liss, Inc.     

Evaluation of host genetic and viral factors as surrogate markers for HTLV‐1‐associated myelopathy/tropical spastic paraparesis in Peruvian HTLV‐1‐infected patients

Human T‐lymphotropic virus 1 (HTLV‐1)‐associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a complication that affects up to 5% of HTLV‐1‐infected individuals. Several host genetic and viral factors have been associated with the risk of HAM/TSP. The aim of this study was to evaluate the performance of a prognostic model for HAM/TSP developed in Japan in a Peruvian population of 71 HAM/TSP patients and 94 asymptomatic carriers (ACs). This model included age, proviral load (PVL), the presence of HLA‐A*02 and HLA‐Cw*08 alleles, SDF‐1 +801, and TNF‐α ?863 polymorphisms, and viral subgroup. We describe frequencies for the four host genetic markers and demonstrate the presence of the HTLV‐1 tax B subgroup in Peru. Using cross‐validation, we show that the predictive ability of the prognostic model, as characterized by the area under the receiver‐operating characteristic curve (AUC), does not differ from a model containing PVL only (both AUC = 0.74). We found some suggestive evidence of a protective effect of the HLA‐A*02 allele but failed to replicate the associations with the other three genetic markers and with viral subgroup. A logistic model containing PVL, age, gender, and HLA‐A*02 provided the best predictive ability in the Peruvian cohort (AUC = 0.79). J. Med. Virol. 82:460–466, 2010. © 2010 Wiley‐Liss, Inc.     

Levels of serum chemokines discriminate clinical myelopathy associated with human T lymphotropic virus type 1 (HTLV-1)/tropical spastic paraparesis (HAM/TSP) disease from HTLV-1 carrier state

Approximately 5% of people infected with human T lymphotropic virus type 1 (HTLV-1) develop clinical myelopathy or tropical spastic paraparesis (HAM/TSP) that is associated with high-levels of Th1 cytokines, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha. Chemokines are known to induce cytokine secretion and direct the trafficking of immune cells to sites of disease. The present study measured serum chemokines correlated with autonomously released IFN-gamma in cell cultures. HTLV-1 infection was defined by enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blot. Subjects included HTLV-1 carriers (n = 56), patients with HAM/TSP (n = 31) and healthy HTLV-1 seronegative volunteer controls (n = 20). Serum chemokines and IFN-gamma autonomously released by mononuclear cells in culture were quantified by ELISA. Compared to HTLV-1 carriers, serum chemokines in HAM/TSP patients showed significantly increased levels of CXCL9 and CXCL10, significantly diminished levels of CCL2 and similar amounts of CCL11 and CCL24. In contrast, CCL11 and CCL24 were significantly lower in serum of HAM/TSP patients than either control. IFN-gamma was positively correlated with CXCL9 and CXCL10 when HAM/TSP and HTLV-1 carriers were used as a combined group. However, despite a large proportion of HTLV-1 carriers having high IFN-gamma levels, these chemokines were not increased in carriers. This study showed that high levels of CXCL9 and CXCL10 in the systemic circulation and low serum CCL2 levels are features of HAM/TSP. HTLV-1 infection and Tax and/or additional viral encoded factor-mediated pathological processes triggering T cell activation with autogenous IFN-gamma release are probably involved in regulating chemokine release.     

Monitoring the HTLV-1 proviral load in the peripheral blood of asymptomatic carriers and patients with HTLV-associated myelopathy/tropical spastic paraparesis from a Brazilian cohort: ROC curve analysis to establish the threshold for risk disease

Human T‐lymphotropic virus 1 (HTLV‐1) infection is associated with HTLV‐associated myelopathy/tropical spastic paraparesis (HAM/TSP), which affects approximately 5% of carriers. High proviral load is a risk marker for HAM/TSP, although there is an overlap of proviral load levels in peripheral blood between asymptomatic carriers and HAM/TSP patients. In this study, receiver operating characteristic curve analysis was used to define a set point of HTLV‐1 proviral load that better indicates an increased risk for HAM/TSP. Proviral load was quantified in 75 asymptomatic carriers and 78 HAM/TSP patients in a Brazilian cohort. The cut‐off of proviral load was defined as 114 copies/10⁴ cells, with 78.2% sensitivity to identify true HAM/TSP patients. The mean proviral load levels were not significantly different between males and females with the same clinical status, and there was no significant correlation between proviral load and age at blood sampling, age at the onset of illness, or duration of disease. In HAM/TSP patients, proviral load was significantly higher in wheelchair‐bound patients than in individuals able to walk without support and in those with the worst spinal cord injuries. Follow‐up of HTLV‐1‐infected individuals showed that proviral load was more stable in asymptomatic carriers than in HAM/TSP patients. In a cohort study, periodically quantifying proviral load in asymptomatic carriers is necessary to identify those at risk for developing neurological disease, and it is necessary for HAM/TSP patients to monitor spinal injury and progression to walking disability. The measure of proviral load in clinical practice implicates the definition of the cut‐off of proviral load and its validation during follow‐up. J. Med. Virol. 84:664–671, 2012. © 2011 Wiley Periodicals, Inc.     

Target epitopes of HTLV-1 recognized by class I MHC-restricted cytotoxic T lymphocytes in patients with myelopathy and spastic paraparesis and infected patients with autoimmune disorders

Human T-cell lymphotropic virus type I (HTLV-1) causes adult T-cell leukemia/lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The different patterns of clinical diseases are thought to be linked to immunogenetic host factors. A variety of autoimmune diseases, such as Sj?gren's syndrome, have been reported in persons infected with HTLV-1, although the precise relationship between these disorders and HTLV-1 infection remains unknown. There is no report on the repertoire of HTLV-1-specific CD8+ T-cells in HAM/TSP patients or carriers with autoimmune diseases, both characterized by an abnormal immune state. In this study, to characterize HTLV-1-specific CD8+ T-cells in asymptomatic HTLV-1 carriers, HAM/TSP patients and carriers with autoimmune diseases, we examined the frequency and diversity of HTLV-1-specific CD8+ T-cells using HTLV-1 tetramers. HTLV-1 Env-specific CD8+ T-cells were significantly more frequent in HAM/TSP and carriers with autoimmune diseases compared with asymptomatic HTLV-1 carriers, while the frequency of HTLV-1 Tax-specific CD8+ T-cells was not significantly different among them. CD8+ cells binding to HTLV-1 Tax tetramers in carriers with autoimmune diseases were significantly reduced compared with HAM/TSP patients. This study demonstrates the importance of CD8+ T-cells recognizing HTLV-1 Env-tetramers in HAM/TSP patients and carriers with autoimmune diseases, thereby suggesting that the diversity, frequency and repertoire of HTLV-1 Env-specific CD8+ T-cell clones may be related to the hyperimmune response in HAM/TSP and carriers with autoimmune diseases, although different immunological mechanisms may mediate the hyperimmunity in these conditions.     

Possible implication of NFKB1A and NKG2D genes in susceptibility to HTLV-1-associated myelopathy/tropical spastic paraparesis in Peruvian patients infected with HTLV-1

The human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a progressive disease causing paraparesis of the lower limbs. Only a minority of persons infected with HTLV-1 develop HAM/TSP. Universal susceptibility factors for HAM/TSP are not known. The viral genotype is similar in asymptomatic carriers and HAM/TSP patients. High proviral load has been associated consistently with HAM/TSP, but this factor does not explain fully the presence of disease in HTLV-1-infected subjects. Most likely, host genetic factors will play an important role in HAM/TSP development. A two-stage case-control study was carried out to evaluate the association between HAM/TSP and candidate single nucleotide polymorphisms (SNPs) from 45 genes in addition to six human leukocyte antigen (HLA) alleles. Ancestry-informative markers were used to correct for population stratification. Several SNPs belonging to NFKB1A and NKG2D showed a trend of association in both stages. The fact that the direction of the association observed in the first stage was the same in the second stage suggests that NFKB1A and NKG2D may be implicated in the development of HAM/TSP. Further replication studies in independent HTLV-1 patient groups should validate further these associations.     

Correlation between polymorphisms at interleukin‐6 but not at interleukin‐10 promoter and the risk of human T lymphotropic virus type I‐associated myelopathy/tropical spastic paraparesis in Brazilian individuals

HTLV‐1 is the etiologic agent of ATL and HAM/TSP. The majority of HTLV‐1‐infected individuals remain asymptomatic, indicating that the infection alone is not sufficient to cause the diseases. It has been reported that cytokine gene polymorphisms, including polymorphisms at IL‐6 and IL‐10 gene, might be important. We analyzed SNP in the promoter region of the IL‐6: ?174, ?572, ?597, and ?634 positions, and IL‐10: ?592 position to evaluate the role of these polymorphisms in the HAM/TSP pathogenesis in 133 HTLV‐1 infected individuals and in 100 healthy individuals from Salvador, Bahia, Brazil. The ?634C allele frequencies were higher among HAM/TSP patients (21.2%) than among oligosymptomatic (6.5%; P = 0.038) and asymptomatic (9.5%; P = 0.025) subjects. Similarly, the ?174G allele frequencies were higher in HAM/TSP patients than in oligosymptomatic patients (P = 0.02). Moreover, the ?634GC/?174GG genotype combination was identified at a higher frequency (38.5%) in the HAM/TSP patients than in subjects with other clinical status (8.7%; P = 0.016 for oligosymptomatic and 15.5%, P = 0.012 for asymptomatic patients). However, the multivariate logistic regression including the genotypes of the three studied loci showed that only ?634 C IL‐6 carriers remain as significant and independent TSP/HAM predictor (odds ratio [OR] = 5.31; 95% [CI] = 1.60–17.56; P = 0.006). We suggest that ?634 G C in IL‐6 could contribute to HAM/TSP development and that identification of the collective influence of several cytokine polymorphisms, their prevalence, and their interaction could help to better understand this disease. J. Med. Virol. 80:2141–2146, 2008. © 2008 Wiley‐Liss, Inc.     

Polymorphisms at GLUT1 gene are not associated with the development of TSP/HAM in Brazilian HTLV‐1 infected individuals and the discovery of a new polymorphism at GLUT1 gene

The development of HTLV‐1 associated clinical manifestations, such as TSP/HAM and ATLL, occur in 2–4% of the infected population and it is still unclear why this infection remains asymptomatic in most infected carriers. Recently, it has been demonstrated that HTLV uses the Glucose transporter type 1 (GLUT1) to infect T‐CD4⁺ lymphocytes and that single nucleotide polymorphisms (SNP) in the GLUT1 gene are associated with diabetic nephropathy in patients with diabetes mellitus in different populations. These polymorphisms could contribute to a higher GLUT1 protein expression on cellular membrane, facilitating the entry of HTLV and its transmission cell by cell. This could result in a higher provirus load and consequently in the development of TSP/HAM. To evaluate the role of GLUT1 gene polymorphisms in the development of TSP/HAM in HTLV‐1 infected individuals, the g.22999G > T, g.15339T > C and c.‐2841A > T sites were analyzed by PCR/RFLP or sequencing in 244 infected individuals and 102 normal controls. The proviral load of the HTLV‐1 infected patients was also analyzed using Real Time Quantitative PCR. Genotypic and allelic frequencies of the three sites did not differ significantly between controls and HTLV‐1 infected individuals. There was no difference in genotypic and allelic distributions among patients as to the presence or absence of HTLV‐1 associated clinic manifestations. As regards the quantification of the provirus load, we observed a significant reduction in the asymptomatic individuals compared with the oligosymptomatic and TSP/HAM individuals. These results suggest that g.22999G > T, g.15339T > C, and c.‐2841A > T SNP do not contribute to HTLV‐1 infection nor to the genetic susceptibility of TSP/HAM in Brazilian HTLV‐1 infected individuals. J. Med. Virol. 81:552–557, 2009. © 2009 Wiley‐Liss, Inc.