Osteopontin-integrin interaction as a novel molecular target for antibody-mediated immunotherapy in adult T-cell leukemia.

BACKGROUND: Adult T-cell leukemia (ATL) is a CD4(+) T-cell neoplasm with a poor prognosis. A previous study has shown that there is a strong correlation between the secreted matricellular protein osteopontin (OPN) level and disease severity in ATL patients. Here, we investigated the role of OPN in ATL pathogenesis and the possible application of anti-OPN monoclonal antibody (mAb) for ATL immunotherapy in NOD/Shi-scid,IL-2Rg (null) (NOG) mice. RESULTS: Subcutaneous inoculation of ATL cell lines into NOG mice increased the plasma level of OPN, which significantly correlated with metastasis of the inoculated cells and survival time. Administration of an SVVYGLR motif-recognizing anti-OPN mAb resulted in inhibition not only of tumor growth but also of tumor invasion and metastasis. The number of fibroblast activating protein-positive fibroblasts was also reduced by this mAb. We then co-inoculated mouse embryonic fibroblasts (MEFs) isolated from wild-type (WT) or OPN knockout mice together with ATL-derived TL-OmI cells into the NOG mice. The mice co-inoculated with WT MEFs displayed a significant decrease in survival relative to those injected with TL-OmI cells alone and the absence of OPN in MEFs markedly improved the survival rate of TL-OmI-inoculated mice. In addition, tumor volume and metastasis were also reduced in the absence of OPN. CONCLUSION: We showed that the xenograft NOG mice model can be a useful system for assessment of the physiological role of OPN in ATL pathogenesis. Using this xenograft model, we found that fibroblast-derived OPN was involved in tumor growth and metastasis, and that this tumor growth and metastasis was significantly suppressed by administration of the anti-OPN mAbs. Our findings will lead to a novel mAb-mediated immunotherapeutic strategy targeting against the interaction of OPN with integrins on the tumor of ATL patients.

Long-term study of indolent adult T-cell leukemia-lymphoma.

The long-term prognosis of indolent adult T-cell leukemia-lymphoma (ATL) is not clearly elucidated. From 1974 to 2003, newly diagnosed indolent ATL in 90 patients (65 chronic type and 25 smoldering type) was analyzed. The median survival time was 4.1 years; 12 patients remained alive for more than 10 years, 44 progressed to acute ATL, and 63 patients died. The estimated 5-, 10-, and 15-year survival rates were 47.2%, 25.4%, and 14.1%, respectively, with no plateau in the survival curve. Although most patients were treated with watchful waiting, 12 patients were treated with chemotherapy. Kaplan-Meier analyses showed that advanced performance status (PS), neutrophilia, high concentration of lactate dehydrogenase, more than 3 extranodal lesions, more than 4 total involved lesions, and receiving chemotherapy were unfavorable prognostic factors for survival. Multivariate Cox analysis showed that advanced PS was a borderline significant independent factor in poor survival (hazard ratio, 2.1, 95% confidence interval, 1.0-4.6; P = .06), but it was not a factor when analysis was limited to patients who had not received chemotherapy. The prognosis of indolent ATL in this study was poorer than expected. These findings suggest that even patients with indolent ATL should be carefully observed in clinical practice. Further studies are required to develop treatments for indolent ATL.

Overexpression of caveolin-1 in adult T-cell leukemia.

Caveolin-1 is implicated in the regulation of signal pathways. Adult T-cell leukemia (ATL) is a T-cell malignancy causatively associated with human T-cell leukemia virus type 1 (HTLV-1). To determine the role of caveolin-1 in leukemogenesis, we examined caveolin-1 expression levels in HTLV-1-infected T-cell lines and ATL cells. These cells expressed high levels of caveolin-1 compared with uninfected T-cell lines and normal peripheral blood mononuclear cells (PBMCs). Caveolin-1-positive ATL cells were detected in ATL lymph nodes and skin lesions, and caveolin-1 was also detected in the plasma of patients with ATL. Infection of a human T-cell line, an epithelial cell line, and normal PBMCs with HTLV-1 induced caveolin-1 expression. The viral protein Tax transcriptionally activated caveolin-1 gene through nuclear factor-kappaB and cAMP response element binding protein signal pathways. HTLV-1-infected T-cell lines, and ATL cells are known to be resistant to transforming growth factor beta (TGF-beta)-induced growth inhibition. Caveolin-1 was colocalized with TGF-beta type I receptor in HTLV-1-infected T-cell lines and suppressed TGF-beta signaling. Caveolin-1 knockdown in an HTLV-1-infected T-cell line exhibited susceptibility to TGF-beta. Thus, we describe a new function for Tax, repression of TGF-beta signaling through caveolin-1 expression, which may play a critical role in ATL leukemogenesis.

Paradoxical expression of IL-28B mRNA in peripheral blood in human T-cell leukemia virus type-1 mono-infection and co-infection with hepatitis C virus.

BACKGROUND: Human T-cell leukemia virus type-1 (HTLV-1) carriers co-infected with and hepatitis C virus (HCV) have been known to be at higher risk of their related diseases than mono-infected individuals. The recent studies clarified that IL-28B polymorphism rs8099917 is associated with not only the HCV therapeutic response by IFN, but also innate immunity and antiviral activity. The aim of our research was to clarify study whether IL-28B gene polymorphism (rs8099917) is associated with HTLV-1/HCV co-infection. RESULTS: The genotyping and viral-serological analysis for 340 individuals showed that IL-28B genotype distribution of rs8099917 SNP did not differ significantly by respective viral infection status. However, the IL-28B mRNA expression level was 3.8 fold higher in HTLV-1 mono-infection than HTLV-1/HCV co-infection. The high expression level was associated with TT (OR, 6.25), whiles the low expression was associated with co-infection of the two viruses (OR, 9.5). However, there was no association between down-regulation and ATL development (OR, 0.8). CONCLUSION: HTLV-1 mono-infection up-regulates the expression of IL-28B transcripts in genotype-dependent manner, whiles HTLV-1/HCV co-infection down-regulates regardless of ATL development.

c-Maf suppresses human T-cell leukemia virus type 1 Tax by competing for CREB-binding protein.

Latent infection of human T-cell leukemia virus type 1 (HTLV-1) is considered to be preferentially associated with CCR4(+) CD4(+) T cells. Here we report that c-Maf, one of the critical transcription factors for Th2 differentiation, suppresses the transcriptional activity of HTLV-1 Tax by competing for CREB-binding protein. Notably, c-maf expression is selectively induced in a fraction of CCR4(+) CD4(+) T cells upon activation. Furthermore, c-Maf significantly decreases Tax-induced HTLV-1 envelope gp46 gene expression from an infectious HTLV-1 molecular clone and tax expression in a cell-free HTLV-1 infection system. Collectively, c-Maf may play a role in latent infection of HTLV-1 in CCR4(+) CD4(+) T cells by negatively regulating Tax activity.

Advantage of higher-avidity CTL specific for Tax against human T-lymphotropic virus-1 infected cells and tumors.

Strong CTL response can be observed and associated with the control of proviral load in human T-lymphotropic virus type 1 (HTLV-1) infection. However, there are few details with regard to how HTLV-1 specific CTLs work against HTLV-1 infected cells and adult T-cell leukemia cells (ATLs). In this study, using Tax-specific CTL lines with high- and low-functional avidity developed from HLA-A2-transgenic mice, we showed that higher avidity CTLs specific for Tax expressing larger numbers of TCRs and better binding strength to the antigen-HLA-A2 complex are much more efficient at eliminating HTLV-1 infected cells and, in particular, ATL tumor cells with the ability of recognizing a latent level of Tax product detected only with a real-time PCR. These findings suggest that such higher avidity CTLs specific for Tax in HTLV-1 could be responsible for preventing the development of HTLV-1 infection by detecting trace amount of antigens.

Overexpression of Enhancer of zeste homolog 2 with trimethylation of lysine 27 on histone H3 in adult T-cell leukemia/lymphoma as a target for epigenetic therapy.

BACKGROUND: Enhancer of zeste homolog 2 is a component of the Polycomb repressive complex 2 that mediates chromatin-based gene silencing through trimethylation of lysine 27 on histone H3. This complex plays vital roles in the regulation of development-specific gene expression. DESIGN AND METHODS: In this study, a comparative microarray analysis of gene expression in primary adult T-cell leukemia/lymphoma samples was performed, and the results were evaluated for their oncogenic and clinical significance. RESULTS: Significantly higher levels of Enhancer of zeste homolog 2 and RING1 and YY1 binding protein transcripts with enhanced levels of trimethylation of lysine 27 on histone H3 were found in adult T-cell leukemia/lymphoma cells compared with those in normal CD4(+) T cells. Furthermore, there was an inverse correlation between the expression level of Enhancer of zeste homolog 2 and that of miR-101 or miR-128a, suggesting that the altered expression of the latter miRNAs accounts for the overexpression of the former. Patients with high Enhancer of zeste homolog 2 or RING1 and YY1 binding protein transcripts had a significantly worse prognosis than those without it, indicating a possible role of these genes in the oncogenesis and progression of this disease. Indeed, adult T-cell leukemia/lymphoma cells were sensitive to a histone methylation inhibitor, 3-deazaneplanocin A. Furthermore, 3-deazaneplanocin A and histone deacetylase inhibitor panobinostat showed a synergistic effect in killing the cells. CONCLUSIONS: These findings reveal that adult T-cell leukemia/lymphoma cells have deregulated Polycomb repressive complex 2 with over-expressed Enhancer of zeste homolog 2, and that there is the possibility of a new therapeutic strategy targeting histone methylation in this disease.

In vivo efficacy of doripenem (DRPM) against Pseudomonas aeruginosa in murine chronic respiratory tract infection model.

Doripenem is a carbapenem antibiotic with broad-spectrum coverage of gram-positive and gram-negative bacteria, including Pseudomonas aeruginosa, and is considered to be as effective as meropenem. The in vivo activity of doripenem was thus compared with that of meropenem in a chronic lower respiratory P. aeruginosa infection mouse model. The number of viable bacteria in the lungs of mice after treatment with doripenem, meropenem, and saline was 2.01 ± 0.69, 2.03 ± 0.48, and 3.90 ± 1.40 log10 CFU/lung, respectively. The number of viable bacteria in the lungs of mice treated with doripenem and meropenem was significantly lower than that in lungs of controls. Histopathological examination of lung specimens from the control group revealed promotion of the inflammatory response in chronic bronchial infection. However, the groups treated with doripenem and meropenem showed weaker inflammatory responses. These results suggest that doripenem treatment is effective against chronic airway infection with P. aeruginosa.

Nationwide survey of adult T-cell leukemia/lymphoma (ATL) in Japan.

In a nationwide survey of ATL in Japan, a total of 910 cases of ATL and 7,164 cases of B-NHL as a control disease, newly diagnosed from January 2006 to December 2007 (2 years), were enrolled from 156 hospitals. Male-female ratios were 1.16 for ATL and 1.22 for B-NHL. Among all ATL cases registered, 59.8% were from an HTLV-1 endemic area in Kyushu, and the ratio of ATL to B-NHL in this area was 1 to 3, while that in a non-endemic area in Tokyo was 1 to 40. Compared to previous nationwide studies, the age of ATL patients shifted toward older ages and the mean age gradually increased from 52.7 years in the first survey (cases before 1980) to 61.1 years in the ninth survey (1996-1997) and, finally, to 66.0 years in the present study (range: 19 to 94, median: 67). On subtype classification, 46.7% were classified as the acute type, 34.8% the lymphoma type, 10.3% the smoldering type, and 8.2% the chronic type, and the rate of the acute type decreased with an increase in the lymphoma type compared to that in previous studies. An increase in the mean age is explained by the high HTLV-1 prevalence in elderly people over 64 years old in endemic areas (20%), and by the continual development of ATL from this large pool of HTLV-1 carriers. According to mortality statistics from the Ministry of Health, Labor and Welfare in Japan, approximately 1,000 people die annually from ATL, a statistic that has not changed at least for the past decade.

Trends in HTLV-1 prevalence and incidence of adult T-cell leukemia/lymphoma in Nagasaki, Japan.

Most previous studies aimed at estimating the number of human T-cell leukemia virus type-1 (HTLV-1) carriers in endemic areas have been based on seroprevalence rates in blood donors; however, this may result in underestimation because of the healthy donor effect. People who have health problem do not donate blood. In the present study, the number of HTLV-1 carriers in Nagasaki City was estimated based on the seroprevalence rates in a hospital-based population from Nagasaki University Hospital. In accordance with previous reports, seroprevalence of HTLV-1 was higher in females, and year of birth-specific seroprevalence showed a significant annual decline in both genders (P for trend: <0.0001). The estimated number of HTLV-1 carriers in Nagasaki City was 36,983. The incidence of adult T-cell leukemia/lymphoma (ATLL) among HTLV-1 carriers was estimated using data from the Nagasaki Prefectural Cancer Registry. The estimated annual incidence of ATLL was 61 per 100,000 HTLV-1 carriers, and the crude lifetime risk of the development was 7.29% for males and 3.78% for females. There is a large pool of HTLV-1 carriers aged over 70 years, and a continuing development of cases of ATLL among the elderly is therefore expected.

Legionella pneumophila induces cathepsin B-dependent necrotic cell death with releasing high mobility group box1 in macrophages.

BACKGROUND: Legionella pneumophila (LPN) can cause a lethal infectious disease with a marked inflammatory response in humans. However, the mechanism of this severe inflammation remains poorly understood. Since necrosis is known to induce inflammation, we investigated whether LPN induces necrosis in macrophages. We also analyzed the involvement of lysosomal cathepsin B in LPN-induced cell death. METHODS: The human monocytic cell line THP-1 was infected with LPN, NUL1 strain. MG132-treated cells were used as apoptotic control cells. After infection, the type of cell death was analyzed by using microscopy, LDH release and flow cytometry. As a proinflammatory mediator, high-mobility group box 1 (HMGB-1), was measured. Cathepsin B activity was also measured and the inhibitory effects of cathepsin B on LPN-induced cell death were analyzed. RESULTS: THP-1 cells after treatment with high dose of LPN showed necrotic features with releasing HMGB-1. This necrosis and the HMGB-1 release were inhibited by a specific lysosomal cathepsin B inhibitor and were characterized by a rapid and high activation of cathepsin B that was not observed in apoptotic control cells. The necrosis was also accompanied by cathepsin B-dependent poly(ADP-ribose) polymerase (PARP) cleavage. CONCLUSIONS: We demonstrate here that L. pneumophila rapidly induces cathepsin B-dependent necrosis in a dose-dependent manner and releases a proinflammatory mediator, HMGB-1, from macrophages. This report describes a novel aspect of the pathogenesis of Legionnaires' disease and provides a possible therapeutic target for the regulation of inflammation.

High human T cell leukemia virus type-1(HTLV-1) provirus load in patients with HTLV-1 carriers complicated with HTLV-1-unrelated disorders.

BACKGROUND: To address the clinical and virological significance of a high HTLV-1 proviral load (VL) in practical blood samples from asymptomatic and symptomatic carriers, we simultaneously examined VL and clonal expansion status using polymerase chain reaction (PCR) quantification (infected cell % of peripheral mononuclear cells) and Southern blotting hybridization (SBH) methods. RESULTS: The present study disclosed extremely high VL with highly dense smears with or without oligoclonal bands in SBH. A high VL of 10% or more was observed in 16 (43.2%) of a total of 33 samples (one of 13 asymptomatic carriers, 8 of 12 symptomatic carriers, and 7 of 8 patients with lymphoma-type ATL without circulating ATL cells). In particular, an extremely high VL of 50% or more was limited to symptomatic carriers whose band findings always contained at least dense smears derived from polyclonally expanded cells infected with HTLV-1. Sequential samples revealed that the VL value was synchronized with the presence or absence of dense smears, and declined at the same time as disappearing dense smears. Dense smears transiently emerged at the active stage of the underlying disease. After disappearance of the smears, several clonal bands became visible and were persistently retained, explaining the process by which the clonality of HTLV-1-infected cells is established. The cases with only oligoclonal bands tended to maintain a stable VL of around 20% for a long time. Two of such cases developed ATL 4 and 3.5 years later, suggesting that a high VL with oligoclonal bands may be a predisposing risk to ATL. CONCLUSION: The main contributor to extremely high VL seems to be transient emergence of dense smears detected by the sensitivity level of SBH, corresponding to polyclonal expansion of HTLV-1-infected cells including abundant small clones. Major clones retained after disappearance of dense smears stably persist and acquire various malignant characteristics step by step.

In vivo efficacy of sivelestat in combination with pazufloxacin against Legionella pneumonia.

It is important to regulate excessive inflammation when patients with severe infectious disease are treated. Sivelestat sodium hydrate (sivelestat), a neutrophil elastase inhibitor, is used in the treatment of lung injury but its effect on bacterial pneumonia is unknown. The authors examined the efficacy of sivelestat in combination with a fluoroquinolone in a Legionella pneumophila pneumonia mouse model. The combination therapy did not show a significant survival improvement compared to the treatment with fluoroquinolone alone, but reduced bacteria number and inflammatory cells in the early phase. The combination therapy can contribute to treatment of L. pneumophila pneumonia with protecting lungs.

Genetic diagnosis of community-acquired MRSA: a multiplex real-time PCR method for Staphylococcal cassette chromosome mec typing and detecting toxin genes.

Methicillin-resistant Staphylococcus aureus (MRSA) causes a wide range of infections in health care settings and community environments. In particular, community-acquired MRSA (CA-MRSA) is important for clinicians because many fatal cases in healthy populations have been reported. Staphylococcal cassette chromosome mec (SCCmec) is a mobile genetic element and carries the central determinant for broad-spectrum beta-lactam resistance encoded by the mecA gene. The emergence of MRSA is due to the acquisition and insertion of the SCCmec element into the chromosome. CA-MRSA is characterized as SCCmec type IV. Thus, we aimed to establish a novel multiplex real-time PCR method to distinguish SCCmec type, which enables us to evaluate the pathogenicity of MRSA. A total of 778 MRSA were isolated at Nagasaki University Hospital from 2000 to 2007. All isolates were subjected to minimal inhibitory concentration testing and PCR for SCCmec typing and detecting genes of toxins: tst (toxic shock syndrome toxin 1), sec (encoded enterotoxin type c), etb (exfoliative toxin type b), and lukS/F-PV (Panton-Valentine leukocidin). PCR was performed to amplify a total of 10 genes in the same run. The 667 MRSA clones detected from pus in 778 clones were classified as SCCmec type II (77.7%), type IV (19.2%), and type I (3.0%). 87.5% of SCCmec type II clone had tst and sec genes. No isolate was lukS/F-PV positive. The present study indicates the high rate of lukS/F-PV-negative SCCmec type IV in Nagasaki. Our PCR method is convenient for typing MRSA and detecting toxins in Japan.

CXCR7 is inducible by HTLV-1 Tax and promotes growth and survival of HTLV-1-infected T cells.

Human T-lymphotropic virus type 1 (HTLV-1), the etiological agent of adult T-cell leukemia (ATL), encodes the potent transcriptional activator Tax, which is required for HTLV-1-induced immortalization of T cells. CXCR7 is an atypical chemokine receptor frequently expressed by tumor cells and known to promote cell growth and survival. We found that HTLV-1-immortalized T cells expressing Tax consistently expressed CXCR7. Induction of Tax in JPX-9 upregulated CXCR7. Wild-type Tax efficiently activated the CXCR7 promoter via a proximal NF-kappaB site, while a mutant Tax selectively defective in NF-kappaB activation did not. CCX754, a synthetic CXCR7 antagonist, inhibited cell growth and increased apoptosis of HTLV-1-immortalized T cells. Knockdown of CXCR7 by small interfering RNA also reduced cell growth. Stable expression of CXCR7 in a CXCR7-negative ATL cell line promoted cell growth and survival. Taken together, CXCR7 is inducible by Tax and may play an important role in HTLV-1-induced immortalization of T cells by promoting growth and survival of HTLV-1-infected T cells.

Aberrant p53 protein expression and function in a panel of hematopoietic cell lines with different p53 mutations.

The p53 gene is one of the most important genes involved in carcinogenesis and its role in part has been clarified by research using cell lines. To know the comprehensive characteristics of 22 hematopoietic cell lines (T, 13 and non-T, nine lines), the relationship between p53 mutational status, its altered functioning, and its mRNA and protein levels were examined. p53 mutations were less frequent in T-cell lines (38% vs. 78%) with mainly single nucleotide substitutions generating missense codons. Of 22 different p53 mutations, 12 (54.5%) resulted in mutated proteins, with the mutations clustering mainly in the sequence-specific DNA-binding site region located from amino acid residues 102 to 292. p53 mRNA and protein assays determined that wild-type cell lines expressed constant levels of both mRNA and protein, but mutated cell lines demonstrated two expression patterns: protein over-expression with reduced mRNA levels, because of missense mutations; and protein under-expression with little mRNA expression, because of other mutations. The resistance to Nutlin (MDM2 inhibitor)-induced apoptosis was associated with p53 mutations independently of MDM2 expression levels. This clarification of the unique associations in cell lines useful for bio-medical studies will contribute to a better understanding of p53-associated carcinogenesis.

Azithromycin, clarithromycin and telithromycin inhibit MUC5AC induction by Chlamydophila pneumoniae in airway epithelial cells.

BACKGROUND: Airway mucus hypersecretion is an important problem in chronic respiratory diseases including bronchial asthma. Chlamydophila pneumoniae is recently confirmed to be a pathogen in bronchial asthma, but the relationship between C. pneumoniae and mucus hypersecretion is uncertain. In this study, we examined whether C. pneumoniae induces MUC5AC mucin in airway epithelial cells. We also examined the effects of macrolide and ketolide antibiotics on the C. pneumoniae-induced mucus production. METHODS: MUC5AC production in bronchial epithelial cells after stimulation with C. pneumoniae was analyzed by ELISA and quantitative RT-PCR. NF-kappaB and phosphorylated ERK were also analyzed. For inhibition study, cells were pretreated with azithromycin, clarithromycin and telithromycin before stimulation. RESULTS: C. pneumoniae dose-dependently induced MUC5AC production and gene expression. The ERK-NF-kappaB pathway was involved in C. pneumoniae-induced MUC5AC production. Macrolides and ketolides dose-dependently reduced C. pneumoniae-induced MUC5AC production. However, azithromycin was apparently less effective than the other antibiotics. Clarithromycin and telithromycin, but not azithromycin, reduced NF-kappaB activation. CONCLUSIONS: Clarithromycin and telithromycin were thought to interfere with the signal pathways between ERK and NF-kappaB. These results suggest that airway mucus hypersecretion is one of the mechanisms of C. pneumoniae-induced bronchial asthma, and that macrolide and ketolide antibiotics represent a novel therapeutic intervention in these patients.

Elevation of serum KL-6 glycoprotein or surfactant protein-D in adult T-cell leukemia with distinct pulmonary complications.

Patients with hematological malignancies frequently suffer from lung diseases as a complication. However, it is difficult to discriminate leukemic invasion into the lung from infectious pulmonary complications. The serum level of Krebs von den Lungen-6 (KL-6), which is a mucin-like glycoprotein, is increased in more than 70% of patients with interstitial pneumonia. Surfactant protein-D (SP-D) is produced mainly in the lung by alveolar type II and bronchiolar epithelial cells and is a useful serum marker for interstitial pneumonia. We therefore measured the levels of KL-6 and SP-D in sera from 128 patients (76 males and 52 females, mean age: 59 years) with hematological malignancies, including adult T-cell leukemia (ATL). Overall, the increase in KL-6 or SP-D, above each cut-off value (500 U/ml for KL-6 and 110 ng/ml for SP-D), was detected in 11 patients (8.6%) or 10 patients (7.8%), respectively. In contrast, among 67 ATL patients, 15 patients had high serum levels of KL-6 and/or SP-D; both were elevated in 2 patients, only KL-6 was elevated in 6 patients and only SP-D was elevated in 7 patients. Thus, serum KL-6 and SP-D appear to be elevated in a mutually exclusive manner in ATL. Indeed, high serum levels of KL-6 were closely related to the stage of ATL, while the serum SP-D was elevated in ATL patients with pulmonary infection. In conclusion, the combined measurement of KL-6 and SP-D in ATL may become a useful means to discriminate leukemic pulmonary lesions from infectious pulmonary complications.

Characteristic expression of HTLV-1 basic zipper factor (HBZ) transcripts in HTLV-1 provirus-positive cells.

BACKGROUND: HTLV-1 causes adult T-cell leukemia (ATL). Although there have been many studies on the oncogenesis of the viral protein Tax, the precise oncogenic mechanism remains to be elucidated. Recently, a new viral factor, HTLV-1 basic Zip factor (HBZ), encoded from the minus strand mRNA was discovered and the current models of Tax-centered ATL cell pathogenesis are in conflict with this discovery. HBZs consisting of non-spliced and spliced isoforms (HBZ-SI) are thought to be implicated in viral replication and T-cell proliferation but there is little evidence on the HBZ expression profile on a large scale. RESULTS: To investigate the role of HBZ-SI in HTLV-1 provirus-positive cells, the HBZ-SI and Tax mRNA loads in samples with a mixture of infected and non-infected cells were measured and then adjusted by dividing by the HTLV-I proviral load. We show here that the HBZ-SI mRNA level is 4-fold higher than non-spliced HBZ and is expressed by almost all cells harboring HTLV-1 provirus with variable intensity. The proviral-adjusted HBZ-SI and Tax quantification revealed a characteristic imbalanced expression feature of high HBZ and low Tax expression levels in primary ATL cells or high HBZ and very high Tax levels in HTLV-1-related cell lines (cell lines) compared with a standard expression profile of low HBZ and low Tax in infected cells. Interestingly, according to the mutual Tax and HBZ expression status, HTLV-1-related cell lines were subcategorized into two groups, an ATL cell type with high HBZ and low Tax levels and another type with high Tax and either high or low HBZ, which was closely related to its cell origin. CONCLUSION: This is the first comprehensive study to evaluate the mutual expression profile of HBZ and Tax in provirus-positive cells, revealing that there are quantitative and relative characteristic features among infected cells, primary ATL cells, and cell lines.

Subinhibitory concentrations of telithromycin, clarithromycin and azithromycin reduce methicillin-resistant Staphylococcus aureus coagulase in vitro and in vivo.

BACKGROUND: Subinhibitory levels of clarithromycin and azithromycin have been shown to reduce the activity of bacterial virulence factors, but few studies have examined the effects of subinhibitory levels of telithromycin. Here, we examined the effects of telithromycin, clarithromycin and azithromycin on methicillin-resistant Staphylococcus aureus (MRSA) coagulase in vitro. We also examined the effects of these antibiotics on bacterial survival in a murine model of pulmonary infection, in which the number of bacteria in the lung correlates with the coagulase titre. METHODS: The coagulase titre in MRSA strain NUMR101, a clinical isolate, was measured after a 16 h treatment with telithromycin, clarithromycin or azithromycin at the MIC (512 mg/L) and 1/2, 1/4, 1/8 and 1/16 of the MIC. In addition, we examined the effect of these drugs in a murine model of pulmonary infection induced by the intravenous injection of S. aureus enmeshed in agar beads. Treatment was started 1 day before infection and mice were treated once a day for 7 days by oral administration of 10 or 100 mg/kg telithromycin, clarithromycin or azithromycin, and the number of viable bacteria in the lungs was counted 24 h after the injection of the bacteria. RESULTS: The coagulase titres in mice treated with 1/8 of the MIC of telithromycin, clarithromycin and azithromycin and in the control were 8, 4, 8 and 32, respectively. In the mouse model of infection, the log cfu/lung (mean +/- SEM; n = 5 or 6) were 6.62 +/- 0.81, 4.79 +/- 0.41, 6.15 +/- 0.38 and 8.41 +/- 0.30 for mice treated with 100 mg/kg/day of telithromycin, clarithromycin and azithromycin and for controls, respectively (P < 0.05 for all groups versus control). CONCLUSIONS: Subinhibitory concentrations of telithromycin inhibit MRSA coagulase in vitro. In addition, the in vivo results indicate that pre-treatment with telithromycin, clarithromycin or azithromycin can reduce the bacterial load in a murine model of pulmonary infection.