Extracellular human T cell leukemia virus type I tax protein stimulates the proliferation of human synovial cells

IL28B gene polymorphisms and Th1/Th2 cytokine levels might be associated with HTLV-associated arthropathy

The present study is the first investigation of the association between single nucleotide polymorphisms (SNPs - rs8099917, rs12979860 and rs8103142) of the IL28B gene and the development of human T-lymphotropic virus (HTLV)-associated arthropathy (HAA). Individuals with HAA exhibited low interleukin (IL) 6 (p<0.05) and high IL-10 (p<0.05) levels compared with asymptomatic patients. TNF-α/CD4(+) T cell count, TNF-α/CD8(+) T cell count and IFN-γ/proviral load positively correlated in asymptomatic patients. The allelic and genotypic frequencies did not differ between patients with HAA and asymptomatic patients. Seven haplotypes were detected in the investigated population, with haplotype CCT (p<0.05) being the most frequent among the HTLV-infected individuals, while haplotype TTG (p<0.05) was detected in the group with HAA only. Compared with asymptomatic patients, individuals with HAA and genotype TT (rs8099917) exhibited larger numbers of CD8(+) T cells (p<0.05) and higher proviral load levels (p<0.05). Those patients with HAA and genotypes CC (rs12979860) and TT (rs8103142) exhibited high TNF-β (p<0.05) and IFN-γ (p<0.05) levels. Those patients with HAA and genotype CT/TT (rs12979860) exhibited high IL-10 levels (p<0.05). These results suggest that haplotypes CCT and TTG might be associated with susceptibility to HTLV infection and progression to HAA, respectively. Genotype TT (rs8099917) might be a risk factor for elevation of the proviral load and CD8(+) T cell count. In addition, genotypes CC (rs12979860) and TT (rs8103142) seem to be associated with increased TNF-β and IFN-γ levels.

Ultrasonography and magnetic resonance imaging findings of rheumatoid arthritis-like arthritis in a patient with adult T-cell leukemia

A 43-year-old Japanese woman with adult T-cell leukemia (ATL) developed rheumatoid arthritis-like polyarthritis with dermatitis and skin erosion. Her rheumatoid factor and C-reactive protein results were positive. Musculoskeletal ultrasonography showed intra-articular and peritendinous power Doppler signal-positive synovitis. Plain magnetic resonance imaging showed synovitis of the above lesion and remarkable bone marrow edema/osteitis. She was diagnosed as having ATL-associated arthritis based on the invasion of ATL cells by skin biopsy at the arthritis lesion.

Human T-lymphotropic virus type 1 (HTLV-1) and regulatory T cells in HTLV-1-associated neuroinflammatory disease

Human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus that is the causative agent of adult T cell leukemia/lymphoma (ATL) and associated with multiorgan inflammatory disorders, including HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and uveitis. HTLV-1-infected T cells have been hypothesized to contribute to the development of these disorders, although the precise mechanisms are not well understood. HTLV-1 primarily infects CD4(+) T helper (Th) cells that play a central role in adaptive immune responses. Based on their functions, patterns of cytokine secretion, and expression of specific transcription factors and chemokine receptors, Th cells that are differentiated from naïve CD4(+) T cells are classified into four major lineages: Th1, Th2, Th17, and T regulatory (Treg) cells. The CD4(+)CD25(+)CCR4(+) T cell population, which consists primarily of suppressive T cell subsets, such as the Treg and Th2 subsets in healthy individuals, is the predominant viral reservoir of HTLV-1 in both ATL and HAM/TSP patients. Interestingly, CD4(+)CD25(+)CCR4(+) T cells become Th1-like cells in HAM/TSP patients, as evidenced by their overproduction of IFN-γ, suggesting that HTLV-1 may intracellularly induce T cell plasticity from Treg to IFN-γ(+) T cells. This review examines the recent research into the association between HTLV-1 and Treg cells that has greatly enhanced understanding of the pathogenic mechanisms underlying immune dysregulation in HTLV-1-associated neuroinflammatory disease.

A case of human T lymphotropic virus type I-associated synovial swelling

BACKGROUND

Human T lymphotropic virus type 1 (HTLV-I) is associated with T-cell activation, proliferation, and leukemogenesis. HTLV-I is the causative agent of adult T cell leukemia/lymphoma and is associated with myelopathy/tropical spastic paraparesis, uveitis, polymyositis, synovitis, thyroiditis, and bronchoalveolar pneumonia. Since T-cell abnormalities are present in those infected with HTLV-I, the clinical problems might result from abnormal immune function or from direct leukemic or lymphomatous cell infiltration of tissues in the body. Distinguishing between these potential causes might be difficult in patients with joint involvement since the clinical findings can be similar. Consequently, obtaining synovial tissue for analyses is likely to be helpful in determining which process is causing the clinical symptoms.

INVESTIGATIONS

Physical examination, comprehensive metabolic panel, complete blood counts, urinalysis, serological testing for rheumatoid factor, antinuclear antibodies, hepatitis, and cytomegalovirus; western blot for HTLV-I/II, lymphocyte phenotyping of peripheral blood, polymerase chain reaction, plain radiographic imaging, CT, MRI skin biopsy with immunohistochemical analysis, lymph node biopsy with immunohistochemical analysis, lymphocyte phenotyping of synovial fluid, synovial tissue biopsy with immunohistochemical analysis of synovial tissue, and synovial tissue culture.

DIAGNOSIS

HTLV-I infected synovial cells in conjunction with leukemic/lymphomatous infiltration of synovial tissue.

MANAGEMENT

Chemotherapy protocol using alemtuzumab.

Modulation of dendritic cell maturation and function by the Tax protein of human T cell leukemia virus type 1

Human T cell leukemia virus type 1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is characterized by the generation of an intense CTL cell response directed against the viral transactivator protein Tax. In addition, patients diagnosed with HAM/TSP exhibit rapid activation and maturation of dendritic cells (DC), likely contributing to the robust, Tax-specific CTL response. In this study, extracellular Tax has been shown to induce maturation and functional alterations in human monocyte-derived DC, critical observations being confirmed in freshly isolated myeloid DC. Tax was shown to promote the production of proinflammatory cytokines and chemokines involved in the DC activation process in a dose- and time-dependent manner. Furthermore, Tax induced the expression of DC activation (CD40, CD80, and CD86) and maturation (CD83) markers and enhanced the T cell proliferation capability of DC. Heat inactivation of Tax resulted in abrogation of these effects, indicating a requirement for the native structure of Tax, which was found to bind efficiently to the DC membrane and was internalized within a few hours, suggesting that extracellular Tax may possess an intracellular mechanism of action subsequent to entry. Finally, inhibitors of cellular signaling pathways, NF-kappaB, protein kinase, tyrosine kinase, and phospholipase C, were shown to inhibit Tax-mediated DC activation. This is the first study reporting the immunomodulatory effects of extracellular Tax in the DC compartment. These results suggest that DC, once exposed to Tax by uptake from the extracellular environment, can undergo activation, providing constant antigen presentation and costimulation to T cells, leading to the intense T cell proliferation and inflammatory responses underlying HAM/TSP.

Human T-lymphotropic virus 1: recent knowledge about an ancient infection

Human T-lymphotropic virus 1 (HTLV-1) has infected human beings for thousands of years, but knowledge about the infection and its pathogenesis is only recently emerging. The virus can be transmitted from mother to child, through sexual contact, and through contaminated blood products. There are areas in Japan, sub-Saharan Africa, the Caribbean, and South America where more than 1% of the general population is infected. Although the majority of HTLV-1 carriers remain asymptomatic, the virus is associated with severe diseases that can be subdivided into three categories: neoplastic diseases (adult T-cell leukaemia/lymphoma), inflammatory syndromes (HTLV-1-associated myelopathy/tropical spastic paraparesis and uveitis among others), and opportunistic infections (including Strongyloides stercoralis hyperinfection and others). The understanding of the interaction between virus and host response has improved markedly, but there are still no clear surrogate markers for prognosis and there are few treatment options.

Induction of lactoferrin gene expression in myeloid or mammary gland cells by human T-cell leukemia virus type 1 (HTLV-1) tax: implications for milk-borne transmission of HTLV-1

Human T-cell leukemia virus type 1 (HTLV-1), the causative agent of adult T-cell leukemia, is transmitted vertically via breastfeeding. We have previously demonstrated that lactoferrin, a major milk protein, enhances HTLV-1 replication, at least in part by upregulating the HTLV-1 long terminal repeat promoter. We now report that HTLV-1 infection can induce lactoferrin gene expression. Coculture with HTLV-1-infected MT-2 cells increased the levels of lactoferrin mRNA in myeloid-differentiated HL-60 cells, as well as MCF-7 cells, models of two probable sources (neutrophils and mammary epithelium) of lactoferrin in breast milk. MT-2 cell coculture could be replaced with cell-free culture supernatants of MT-2 cells to exert the same effect. Furthermore, extracellularly administered Tax protein also induced lactoferrin gene expression at physiologically relevant concentrations. In transient-expression assays, Tax transactivated the lactoferrin gene promoter in HL-60 or MCF-7 cells. Experiments with Tax mutants, as well as site-directed mutants of the lactoferrin promoter reporters, indicated that the NF-kappaB transactivation pathway is critical for Tax induction of the lactoferrin gene promoter activity in myeloid-differentiated HL-60 cells, but not in MCF-7 cells. These results suggest that HTLV-1 infection may be able to induce expression of lactoferrin in a paracrine manner in the lactic compartment. Our findings, in conjunction with our previous study, implicate that mutual interaction between HTLV-1 and lactoferrin would benefit milk-borne transmission of this virus.

Rheumatoid arthritis as a hyper-endoplasmic-reticulum-associated degradation disease

We introduce Synoviolin as a novel pathogenic factor in rheumatoid arthritis (RA). Experimental studies indicate that this endoplasmic reticulum (ER)-resident E3 ubiquitin ligase has important functions in the ER-associated degradation (ERAD) system, an essential system for ER homeostasis. Overexpression of Synoviolin in mice causes arthropathy with synovial hyperplasia, whereas heterozygous knockdown results in increased apoptosis of synovial cells and resistance to collagen-induced arthritis in mice. On the basis of these experimental data, we propose that excess elimination of unfolded proteins (that is, 'hyper-ERAD') by overexpression of Synoviolin triggers synovial cell overgrowth and hence a worsening of RA. Further analysis of the hyper-ERAD system may permit the complex pathomechanisms of RA to be uncovered.

Bone marrow cells carrying the env-pX transgene play a role in the severity but not prolongation of arthritis in human T-cell leukaemia virus type-I transgenic rats: a possible role of articular tissues carrying the transgene in the prolongation of arthritis

Transgenic rats carrying the env-pX gene of human T-cell leukaemia virus type-I (env-pX rats) were immunized with type II collagen (CII), and chronological alterations of arthritis were compared with findings of collagen-induced arthritis (CIA) in wildtype Wistar-King-Aptekman-Hokudai (WKAH) rats. Arthritis induced by CII in env-pX rats was more severe and persisted longer than CIA in WKAH rats. To determine whether the phenomenon is caused mainly by the transgene-carrying lymphocytes or articular tissues, we immunized lethally irradiated env-pX and WKAH rats with reciprocal bone marrow cell (BMC) transplantation. A severe but transient arthritis was induced by CII in WKAH rats reconstituted by env-pX BMC (w/tB/CII rats). On the other hand, in env-pX rats reconstituted by WKAH BMC, arthritis persisted longer than in w/tB/CII rats, although the degree was less at an early phase after CII immunization. These findings suggest that articular tissues rather than the BMCs carrying the env-pX transgene play a role in the prolongation of arthritis in env-pX rats, although BMCs carrying the transgene are associated with the severity of arthritis. When inflammatory cytokines in synovial cells isolated from env-pX rats before they developed arthritis were examined, interleukin-6 (IL-6) was detected at a higher level than in synovial cells from WKAH rats, thus suggesting the critical role of IL-6 in env-pX arthritis.

Increased proviral load in HTLV-1-infected patients with rheumatoid arthritis or connective tissue disease

BACKGROUND

Human T-lymphotropic virus type 1 (HTLV-1) proviral load is related to the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and has also been shown to be elevated in the peripheral blood in HTLV-1-infected patients with uveitis or alveolitis. Increased proliferation of HTLV-1-infected cells in, or migration of such cells into, the central nervous system is also seen in HAM/TSP. In the present study, we evaluated the proviral load in a cohort of HTLV-1-infected patients with arthritic conditions.

RESULTS

HTLV-1 proviral load in the peripheral blood from 12 patients with RA and 6 patients with connective tissue disease was significantly higher than that in matched asymptomatic HTLV-1 carriers, but similar to that in matched HAM/TSP controls. HAM/TSP was seen in one-third of the HTLV-1-infected patients with RA or connective tissue disease, but did not account for the higher proviral load compared to the asymptomatic carrier group. The proviral load was increased in the synovial fluid and tissue from an HTLV-1-infected patient with RA, the values suggesting that the majority of infiltrated cells were HTLV-1-infected. In the peripheral blood from HTLV-1-infected patients with RA or connective tissue disease, HTLV-1 proviral load correlated with the percentages of memory CD4+ T cells and activated T cells, and these percentages were shown to be markedly higher in the synovial fluid than in the peripheral blood in an HTLV-1-infected patient with RA.

CONCLUSIONS

These biological findings are consistent with a role of the retrovirus in the development of arthritis in HTLV-1-infected patients. A high level of HTLV-1-infected lymphocytes in the peripheral blood and their accumulation in situ might play a central role in the pathogenesis of HTLV-1-associated inflammatory disorders. Alternatively, the autoimmune arthritis, its etiological factors or treatments might secondarily enhance HTLV-1 proviral load.

Synoviolin/Hrd1, an E3 ubiquitin ligase, as a novel pathogenic factor for arthropathy

Rheumatoid arthritis (RA) is one of the most critical articular diseases with synovial hyperplasia followed by impairment of quality of life. However, the mechanism(s) that regulates synovial cell outgrowth is not fully understood. To clarify its mechanism(s), we carried out immunoscreening by using antirheumatoid synovial cell antibody and identified and cloned "Synoviolin/Hrd1", an E3 ubiquitin ligase. Synoviolin/Hrd1 was highly expressed in the rheumatoid synovium, and mice overexpressing this enzyme developed spontaneous arthropathy. Conversely, synoviolin/hrd1(+/-) mice were resistant to collagen-induced arthritis by enhanced apoptosis of synovial cells. We conclude that Synoviolin/Hrd1 is a novel causative factor for arthropathy by triggering synovial cell outgrowth through its antiapoptotic effects. Our findings provide a new pathogenetic model of RA and suggest that Synoviolin/Hrd1 could be targeted as a therapeutic strategy for RA.

Non-HIV retroviral associations with rheumatic disease

While the human T-cell lymphotropic virus type I (HTLV-I) is the recognized cause of adult T cell leukemia, it is also associated with non-neoplastic, ostensibly autoimmune conditions, such as tropical spastic paraparesis. Moreover,among carriers of HTLV-I, the virus is strongly implicated in the development of a type of arthritis, which resembles rheumatoid arthritis (RA). Mice transgenic for HTLV-I tax develop RA-like pathology and Sjögren's syndrome. Patients with RA and SS in HTLV-I nonendemic regions, such as the United States, are usually serologically negative for antibodies to the structural proteins of HTLV. However, they appear to harbor HTLV-I tax in their peripheral blood mononuclear cells three times as often as individuals who present as healthy blood donors. Because HTLV-I tax transactivates numerous inflammatory cytokines and is not normally found in the human genome, treatment with tax antisense oligonucleotides may provide a new therapeutic approach for selected RA patients proven to be HTLV-I "tax only" positive.

Signaling and effector pathways

There is increasing evidence that distinct signaling and effector pathways in the rheumatoid synovium result in a cascade of pathophysiologic events. These interactions, which finally lead to progressive joint destruction, are different from all other joint diseases in numerous aspects. As outlined in this review, molecular biology techniques allow detection of key pathways ranging from external stimuli to subcellular gene regulation mechanisms operative in various cells within the rheumatoid synovium. To alter these pathways, inhibitory factors need to be applied to these "hot zones" for an extended period, which can be achieved either by repeated drug administration or by local synthesis using genetically altered synovial cells. Both adenovirus and retroviral constructs, as well as ex vivo and in vivo strategies, can be used for gene transfer into these cells, and routine delivery of "protective" genes into the affected joints might be achieved within the next decade.