Overgrowth of human synovial cells driven by the human T cell leukemia virus type I tax gene

Identification of the inhibitory activity of walnut extract on the E3 ligase Syvn1

Synoviolin (Syvn1), an E3 ubiquitin ligase in endoplasmic reticulum‑associated protein degradation, is involved in rheumatoid arthritis, fibrosis, liver cirrhosis and obesity. We previously demonstrated that Syvn1 negatively regulates the function of peroxisome proliferator‑activated receptor gamma coactivator‑1β (PGC‑1β). In addition, treatment with a Syvn1 inhibitor suppressed weight gain in a mouse model of obesity by activating PGC‑1β via Syvn1 inhibition. It has been suggested that the Syvn1 inhibitors may have therapeutic benefits in obese patients. The present study tested the inhibitory activity of walnut extract, a natural product, on Syvn1 activity. Walnut extract inhibited the effect of Syvn1 on the cell proliferation of rheumatoid synovial cells and repressed the interaction between PGC‑1β and Syvn1 in an in vitro binding assay. Polyubiquitination of PGC‑1β by Syvn1 was suppressed by walnut extract in a concentration‑dependent manner, but walnut extract did not have an inhibitory effect on the autoubiquitination of Syvn1. Treatment with walnut extract in mouse embryonic fibroblasts increased the number of mitochondria, suggesting that exposure to the extract recovered PGC‑1β function. These results demonstrated that constituents of walnut extract may serve as lead compounds in drug development efforts aiming to produce drugs to treat patients with obesity and obesity‑associated metabolic diseases.

Inflammatory manifestations of HTLV-1 and their therapeutic options

Human T lymphotropic virus type 1 (HTLV-1) is one of the most intriguing retroviruses infecting humans. Most commonly, infection remains undetected, since it does not cause obvious harm, yet in 4-9% of patients, this infection can be devastating, causing adult T-cell leukemia/lymphoma and/or HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). This review concentrates on all inflammatory aspects of HTLV-1 infection: HAM/TSP, HTLV-1 associated uveitis, HTLV-1 associated conjunctivitis, sicca syndrome and interstitial keratitis, HTLV-1 associated Sjögren's syndrome, Hashimoto's thyroiditis and Graves' disease, HTLV-1 associated pulmonary disease, infective dermatitis associated with HTLV-1, HTLV-1 associated inflammatory myositis and HTLV-1 associated arthritis. With the exception of HAM/TSP treatment, studies of these conditions are sparse and even for HAM/TSP, the level of evidence is limited. While control or elimination of infection remains a goal, most therapy beyond symptomatic management is directed at the immune response to HTLV-1.

The contribution of Asian researchers to the field of rheumatology

Asia is home to more than half of the world's population and is a region of diverse ethnicity, culture, microbial endemicity, and economic backgrounds. This diversity is also reflected in the heterogeneity among Asian patients with rheumatic diseases in terms of clinical manifestations, disease courses, treatment responses and outcomes, which provides opportunities for researchers to conduct some unique studies. Several disease entities, such as Behçet syndrome, Takayasu arteritis, Kawasaki disease, and immunological disorders associated with human T-lymphotropic virus type 1 (HTLV-1), were first observed and defined in Asia. In addition, the region's researchers have been at the forefront of research in some interesting scientific topics, which has opened up new research avenues in rheumatology, such as the direct targeting of synovial cells in patients with rheumatoid arthritis via activation of the agonistic Fas pathway, establishment of the field of osteoimmunology, the discovery of regulatory T cells and synoviolin, and the development of tocilizumab, a humanized monoclonal antibody against interleukin-6 receptor.

Unscrambling the role of human parvovirus B19 signaling in systemic autoimmunity

Despite enormous progress in understanding how the immune system works, the pathogenesis of autoimmune diseases still remains unclear. Growing evidence indicates that infectious agents can be potent initial triggers, subverting and exploiting host cell signaling pathways. This role is exemplified by the association of parvovirus B19 (B19) with human autoimmune disease. Infection with this common virus exhibits striking similarities with systemic autoimmune diseases, and can be associated with elevated serum autoantibody titers. The B19 virus produces proline-rich, 11-kDa proteins that have been implicated in modulation of host signaling cascades involved in virulence and pathogenesis. Additionally, B19 produces a non-structural protein (NS1) that functions as a transcription regulator by directly binding the p6 promoter and the Sp1/Sp3 transcription factors. The protein is also involved in DNA replication, cell cycle arrest and initiation of apoptotic damage, particularly in erythroid cells. When transfected to non-permissive cells, NS1 recruits the mitochondria cell death pathway. It is even more remarkable that NS1 functions as a trans-acting transcription activator for the IL6 promoter, up-regulating IL6 expression in host cells. Hence, B19 infection may play a pivotal role in triggering inflammatory disorders. By promoting apoptotic damage and trans-activating pro-inflammatory cytokine promoters, B19 may break the delicate balance between cell survival and apoptosis, and may contribute to immune deregulation. Understanding the mechanisms used by B19 to alter the cell signaling machinery may provide further insight into the mechanism by which autoimmune diseases develop.

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.

Immunocytochemical detection of HoxD9 and Pbx1 homeodomain protein expression in Chinese esophageal squamous cell carcinomas

AIM

To evaluate the expression pattern of two novel oncofetal antigens, the HoxD9 and Pbx1 homeoproteins in esophageal squamous cell carcinomas (ESCCs) to determine what role they would play in the carcinogenesis of ESCC.

METHODS

We obtained tissue samples of ESCC from 56 patients who underwent esophagectomy but not preoperative chemotherapy or radiotherapy. The diagnosis of ESCC was established and confirmed by staff pathologists. We used a highly sensitive, indirect, immunocytochemical method to detect HoxD9 and PbX1 proteins. We qualitatively and quantitatively evaluated cells that exhibited and staining using a light microscope.

RESULTS

In all observed carcinoma tissue samples, more than 60% of neoplastic cells stained lightly or strongly for HoxD9, and more than 50% of neoplastic cells stained lightly or strongly for Pbx1.

CONCLUSION

Our data suggest that HoxD9 and Pbx1 are inappropriately expressed in most human esophageal squamous cell carcinoma. Understanding the role of Hox genes in esophageal epithelial cell carcinogenesis may not only augment early detection but also offer new avenues for treatment of this disease.

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.

HTLV-I env protein acts as a major antigen in patients with HTLV-I-associated arthropathy

Our objective was to investigate the pathological mechanisms of HTLV-I (human T-cell leukemia virus type I)-associated chronic arthritis (HAAP) with respect to T-cell response to HTLV-I viral proteins. We examined T-cell clonality and the antigen recognized by T cells from the inflamed synovium of patients with HAAP by using histology, a single-strand conformation polymorphism (SSCP) analysis and T cell receptor (TCR) sequencing. The SSCP analysis showed oligoclonal expansion of T cells in the synovium, suggesting an antigen-mediated stimulation. In contrast, there was less clonal expansion in peripheral blood lymphocytes (PBL). The expression of HTLV-1 env and tax mRNA was detected in the affected synovium as well as in PBL. A number of T-cell clones in the synovium recognized HTLV-I env and tax proteins. Twenty-seven (24.9%) of 109 examined T-cell clones in the joints were HTLV-I env reactive, and 7 clones (6.4%) were HTLV-I tax reactive. Junctional sequence analysis of synovial T cells showed a lack of highly conserved amino acid motifs in the complementarity-determining region 3 (CDR3) of HTLV-I env and tax reactive T cells, suggesting that these cells recognized multiple T-cell epitopes on HTLV-I antigen. These findings suggest that HTLV-I env protein acts as a major antigen and may play a role in the development of arthropathy in patients with HAAP.

The usefulness and the limitations of animal models in identifying targets for therapy in arthritis

Animal models have played a critical role in the history of modern drug development for rheumatoid arthritis (RA). In this chapter I examine the contributions of animal models in arthritis therapy from adjuvant arthritis and COX-1 inhibitors to transgenic mice and biological response modifiers. Advances in knowledge of the mechanisms of connective tissue disease are frequently derived from the study of animal models, and these findings frequently identify therapeutic targets that are subsequently evaluated in animal models. Hence a critical relationship between insights into the pathology of arthritis and the development of novel therapeutic approaches exists around the study of animal models of arthritis. In particular, we examine how the study of collagen-induced arthritis in rodents led to pioneering work in cytokine inhibitors for the successful therapy of RA.

The influence on gene-expression profiling of osteoblasts behavior following treatment with the ionic products of sintered β-dicalcium pyrophosphate dissolution

Sintered dicalcium pyrophosphate (SDCP) is biocompatible to bone tissue both in the in vivo and in vitro model. However, the molecular mechanisms that mediated these processes have yet to be identified. In this study, we investigated the influence of SDCP ions on in vitro osteoblasts behavior. The powder of sintered beta-dicalcium pyrophosphate (SDCP) was dissolved by HCl and then diluted into different concentration of solutions by culture medium used in the osteoblast cell culture. The effects of various concentration of SDCP on bone cell activities were evaluated by using MTT assay. For the differentiation of osteoblasts, alkaline phosphatase (AP) staining, von Kossa stain for mineralized nodules and bone markers messenger ribonucleic acid (mRNA) isolation and identification were performed at 3h, days 1, 3, 7 and 14. In the presence of 10(-8)M SDCP for 14 days, the osteoblasts population was still significantly higher than that of control. In the qualitative analysis for the formation of AP staining colonies and mineralization nodules formation were not affected by SDCP ions. When osteoblasts cultured in the presence of 10(-8)M SDCP ions, the osteocalcin mRNA expression was up-regulated; while the collagen, osteonectin and osteopontin mRNA expression were down-regulated. In this study, we demonstrated that the elevated concentration of calcium and pyrophosphate ions can activate genes of the bone cells. This study will contribute to a better understanding of cell/biomaterial interactions and mechanisms that SDCP affect the bone cells.

Effect of pulse-burst electromagnetic field stimulation on osteoblast cell activities

Electric stimulation has been used successfully to treat a wide range of bone disorders. However, the mechanism by which the electric fields can influence the bone cells behavior remains poorly understood. The purpose of this research was to assess the possible mechanism of the stimulatory effect of pulsed electromagnetic field (PEMF) on bone cells. A PEMF with a frequency of 15 Hz (1 G [0.1 mT]; electric field strength 2 mV/cm) were applied to neonatal mouse calvarial bone cell cultures for 14 days. The temporal effects of PEMF on the osteoblasts were evaluated by the status of proliferation, differentiation, mineralization, and gene expression on the 3rd, 5th, 7th, and 14th days of culture. Our results demonstrated that PEMF stimulation significantly increased the osteoblasts' proliferation by 34.0, 11.5, and 13.3% over the control group after 3, 5, and 7 days' culture. Although the alkaline phosphatase (ALP) staining and the mineralization nodules formation did not change, the ALP activity of the bone cells decreased significantly after PEMF stimulation. Under the PEMF stimulation, there was no effect on the extracellular matrix synthesis, while the osteoprotegerin (OPG) mRNA expression was up regulated and the receptor activator of NF-kappaB ligand (RANKL) mRNA expression were down regulated, compared to the control. In conclusion, the treatment by PEMF of osteoblasts may accelerate cellular proliferation, but did not affect the cellular differentiation. The effect of PEMF stimulation on the bone tissue formation was most likely associated with the increase in the number of cells, but not with the enhancement of the osteoblasts' differentiation.

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.

Potential role ofHOXD9 in synoviocyte proliferation

OBJECTIVE

To investigate the role of HOXD9 in the proliferation activity of cultured synoviocytes as well as the mechanisms that regulate HOXD9 transcription.

METHODS

Synoviocytes from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) were transfected with HOXD9 complementary DNA to establish stable transformants that overexpressed HOXD9. HOXD9 expression was detected by Western blotting with anti-HOXD9 antibody. The growth properties of the transformants were investigated by proliferation and colony formation assays. The expression of basic fibroblast growth factor (bFGF), tumor necrosis factor alpha (TNFalpha), interleukin-1beta, c-Fos, and c-Myc was examined by Western blotting. Transcriptional regulation of HOXD9 was examined by transient cotransfection.

RESULTS

HOXD9 protein was highly expressed in RA synoviocytes, but there was no expression in OA synoviocytes. HOXD9 transfection induced stable HOXD9 protein expression in synoviocytes and showed an increased proliferation rate under both normal and serum-starved conditions, as well as an enhanced capacity to proliferate anchorage independently to form colonies in soft agar cultures, compared with control transfectants. Higher levels of bFGF and c-Fos were detected in HOXD9 transformants than in controls. Transient cotransfection assays of NIH3T3 fibroblasts and synoviocytes showed that HOXD9 activated the luciferase reporter construct containing the highly conserved region (HCR), an autoregulatory element of HOXD9 promoter. This activation was significantly increased by bFGF, suppressed by TNFalpha, and unchanged by transforming growth factor beta in synoviocytes. Human T lymphotropic virus type I tax also activated the luciferase reporter construct containing the HCR and had a synergistic effect with HOXD9 on HCR promoter activation.

CONCLUSION

Our data suggest that HOXD9 plays a potential role in synovial proliferation. In addition, they suggest that the involvement of HOXD9 in the regulation of cellular growth might be mediated, at least in part, by up-regulation of growth-related factors such as bFGF and c-Fos and/or might result from increased transcription activity by its regulators.

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.

Chemokine synthesis and cellular inflammatory changes in lungs of mice bearing p40tax of human T-lymphotropic virus type 1

To elucidate the pathogenic mechanisms of human T-lymphotropic virus type 1 (HTLV-1)-associated lung inflammation, we conducted a histopathological and molecular analysis study using transgenic mice bearing pX region of this virus. In these mice, accumulations of inflammatory cells consisting mainly of lymphocytes were present in peribronchiolar and perivascular areas and alveolar septa, while control littermate mice did not show such changes. In situ hybridization showed that the anatomic distribution of p40tax mRNA was similar to that of inflammatory cells, typically in peribronchiolar areas and to a lesser extent in perivascular and alveolar septa. Inflammatory cytokines, including IL-1beta, tumour necrosis factor-alpha and interferon-gamma, and several chemokines, such as monocyte chemotactic protein-1 (MCP-1), RANTES, macrophage inflammatory protein-1alpha (MIP-1alpha) and IP-10, were detected in lungs of transgenic mice but not control mice. Semiquantitative analysis using reverse transcription-polymerase chain reaction showed a significant correlation between MCP-1 mRNA expression and p40tax mRNA, but not with other chemokines. The gene expression of the above chemokines, with the exception of MIP-1alpha, correlated with the severity of histopathological changes in the lung. Considered together, our results suggested that p40tax synthesis may be involved in the development of lung lesions caused by HTLV-1 through the induction of local production of chemokines.

CBP: A target molecule of HTLV-1 Tax in synoviocyte activation

Previous studies have shown that human T-cell leukemia virus type 1 (HTLV-1) Tax is a key molecule of synoviocyte activation in HTLV-1 associated arthropathy (HAAP). To clarify the molecular mechanism of HTLV-1 Tax-induced transcriptional activation in synoviocytes from HAAP, we investigated the role of cyclicAMP (cAMP)-regulated enhancer (CRE) binding protein (CREB)-binding protein (CBP), as a target molecule of HTLV-1 Tax. Activation of cyclic AMP (cAMP)/protein kinase-A (PK-A) pathway resulted in a significantly high response of CRE promoter in synoviocytes from patients with HAAP as well as in Tax-transiently transfected synoviocytes from patients with rheumatoid arthritis (RA). Mammalian two-hybrid analysis showed that the recruitment of CBP was responsible for CREB activation. Furthermore, PK-A activation induced CBP-Tax complex in synoviocytes from HAAP and the complex contained CREB. These findings demonstrated that complex formation of CBP and Tax is critical for enhanced CREB activity in synoviocytes from HAAP.

Expression of murine HOXD9 during embryonic joint patterning and in human T lymphotropic virus type I tax transgenic mice with arthropathy resembling rheumatoid arthritis

OBJECTIVE

To characterize the expression of murine HOXD9 during normal joint development and in arthritic joints of human T lymphotropic virus type I (HTLV-I) tax transgenic mice and the role of HTLV-I tax in HOXD9 expression.

METHODS

Expression of HOXD9, HOXD1O, HOXD11, HOXD12, and HOXD13 genes in joint tissues at the ankle/foot regions of mouse embryos at day 10 to day 18 of gestation (E10-E18) and neonates within 10 days after birth was determined by reverse transcriptase-polymerase chain reaction and in situ reverse transcription methods. Adult synovial tissues from 5 HTLV-I tax transgenic mice with chronic polyarthritis and 4 nontransgenic (normal) mice were also examined for expression of these HOXD genes. The effect of HTLV-I on HOXD9 expression in cultured synoviocytes was studied by in vitro infection and transfection experiments.

RESULTS

Expression of HOXD9 was detected in embryonic joints, preferentially on articular cartilage, only during the early stages of joint development (up to E15), whereas other HOXD genes were expressed throughout the embryonic and neonatal stages. In adult mice, transcripts of HOXD9 were specifically detected in synovial tissues from 4 of 5 arthritic mice, especially in the lining and sublining synovial cells, but not in synovial tissues of normal mice. Activation of HOXD9 was observed in cultured synoviocytes infected with HTLV-I in vitro as well as in those transfected with HTLV-I tax.

CONCLUSION

Our findings suggest that HOXD9 is involved not only in the early stages of normal joint development, but may also be involved in the pathologic process of arthritis. HTLV-I tax appeared as an activator of this HOX gene in cultured synoviocytes.

EBV Gene Expression Not Altered in Rheumatoid Synovia Despite the Presence of EBV Antigen-Specific T Cell Clones

T cells infiltrating the rheumatoid arthritis (RA) joint are oligoclonal, implicating an Ag-driven process, but the putative joint-specific Ags remain elusive. Here we examine expression of selected EBV genes in RA synovia and find no abnormal expression in RA. DNA of CMV and EBV was detectable by PCR in the synovial tissue of RA. RNA of several latent and lytic EBV genes was also detectable. However, there were no differences in EBV gene expression in synovial tissues or peripheral blood when comparing RA with osteoarthritis, Gulf War syndrome, and other disease controls. RA synovia with highly expanded CD8 T cell clones reactive with defined EBV peptide Ags presented by HLA class I alleles lacked evidence of abnormal mRNA expression for the relevant EBV Ag (BZLF1) or lacked amplifiable mRNA (BMLF1). Thus, local production of EBV Ags in synovial tissues may not be the cause of the accumulation of T cell clones specific for these Ags. Instead, APCs loaded with processed EBV peptides may migrate to the synovium. Alternatively, EBV-specific T cell clones may be generated in other tissues and then migrate to synovia, perhaps due to cross-reactive joint-specific Ags or because of expression of homing receptors.

Vasculitic peripheral ulcerative keratitis

The onset of peripheral ulcerative keratitis in the course of a connective tissue disorder, such as rheumatoid arthritis, relapsing polychondritis, or systemic lupus erythematosus, may reflect the presence of potentially lethal systemic vasculitis. Moreover, peripheral ulcerative keratitis may be the first sign of systemic necrotizing vasculitis in patients with Wegener's granulomatosis, polyarteritis nodosa, microscopic polyangiitis, or Churg-Strauss syndrome. Although the exact pathogenesis of this severe corneal inflammation and destruction is not well understood, evidence points to a dysfunction in immunoregulation with immune complexes formed in response to autoantigens or to some unknown microbial antigen depositing in scleral and limbal vessels. These events lead to changes that are mainly responsible for the resulting tissue damage. In pauci-immune vasculitides positive for antineutrophil cytoplasmic antibodies, cell-mediated cytotoxicity may play an important role in the pathogenesis of peripheral ulcerative keratitis. Untreated systemic conditions such as those mentioned above may carry a grave prognosis for the eye and may also be life-threatening. Immunosuppressive therapy with corticosteroids and cytotoxic agents is, we believe, mandatory in the treatment of these multisystem disorders associated with vasculitic peripheral ulcerative keratitis.

Human T cell leukemia virus type-I and rheumatoid arthritis

HTLV-I is a retrovirus known as an oncogenic virus for human. This virus, initially found as a causative agent for adult T cell leukemia, has been lately focused as a causative virus for several autoimmune disorders. Here we described the characteristics of polyarthritis in HTLV-I careers, which is indistinguishable from idiopathic rheumatoid arthritis (RA). The relationship between arthritis and this virus was clearly proved by epidimiological study. Moreover, we presented transactivating gene of this virus, tax, is responsible for proliferation of synovial cells. This was proved by Tax transgenic mice, which present chronic destructive arthritis resembling human RA. Other autoimmune disorders, such as Sjögren's syndrome and uveitis, are also reviewed.

Human parvovirus B19 in rheumatoid arthritis

Viral arthritis occurs transiently in most cases, because the infection is self limiting. The arthropathy associated with human parvovirus B19, however, often lasts for more than 2 years and their clinical symptoms may resemble with those of rheumatoid arthritis. Data have been accumulating for the link of B19 infection with chronic polyarthropathy or rheumatoid arthritis (RA), and we discuss the possible mechanism for the role of B19 in the etiopathology of RA.

Thrombin receptor mediated signals induce expressions of interleukin 6 and granulocyte colony stimulating factor via NF-kappa B activation in synovial fibroblasts

OBJECTIVE

To clarify the mechanism of thrombin receptor mediated signal transduction and the induction of cytokines by thrombin stimulation in rheumatoid synovial fibroblasts.

METHODS

Cytokines were measured by enzyme linked immunosorbent assay (ELISA) in the supernatants of cultured rheumatoid synovial fibroblasts stimulated by thrombin. To assess the mechanism of thrombin receptor mediated signal transduction in the rheumatoid synovial fibroblasts, electrophoretic mobility gel shift assay (EMSA), immunoglobulin kappa-chloramphenicol acetyltransferase (CAT) assay, and immunostaining for NF-kappa B subunit molecule was performed.

RESULTS

Thrombin stimulation activated the inducible transcription factor NF-kappa B, and then induced subsequent expressions of interleukin 6 (IL6) and granulocyte colony stimulating factor (G-CSF) in the cells.

CONCLUSION

Thrombin receptor mediated signal transduction could induce the expressions of IL6 and G-CSF, and increase inflammatory events in the cavum articulare via NF-kappa B activation.

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

OBJECTIVE

The present study was designed to investigate whether the proliferation of normal synovial cells from patients with meniscus injury is stimulated by human T cell leukemia virus type I (HTLV-I) Tax protein.

METHODS

The effect of Tax protein on the proliferation of synovial cells was evaluated using a 3H-thymidine incorporation assay. Production of cytokines was determined by enzyme-linked immunosorbent assay. Nuclear factor kappaB (NF-kappaB) DNA binding activity and the transcription of several NF-kappaB-mediated genes was detected by electrophoretic mobility shift assay and reverse transcriptase-polymerase chain reaction.

RESULTS

The proliferation of synovial cells, as well as their expression of tumor necrosis factor alpha, granulocyte-macrophage colony-stimulating factor, and interleukin-6, was significantly enhanced by extracellular Tax at concentrations of 2.5 pM to 25 nM. In contrast, extracellular bacterial extract did not change the cytokine expression or the proliferation of these cells. Proliferation of synovial cells induced by Tax protein may be due to activated expression of several cytokines and protooncogenes that contain NF-kappaB regulatory sequences.

CONCLUSION

Our results suggest that extracellular Tax can regulate the expression of endogenous cellular genes in synovial cells and may contribute to the NF-kappaB-mediated synovial hyperplasia.

Monoclonal expansion of synoviocytes in rheumatoid arthritis

OBJECTIVE

To examine whether synoviocytes from patients with rheumatoid arthritis (RA) have a stronger growth ability than those from patients with osteoarthritis (OA), and to determine whether these synoviocytes clonally expand in situ.

METHODS

Synovial tissues from 13 RA patients and 4 OA patients were cultured, and their ability to form colonies in soft agarose was examined. RA and OA synoviocytes were also examined in varying concentrations of fetal calf serum (FCS)-containing medium to test the effects of FCS on colony formation. DNA was extracted from clones with colony-forming ability in nonpannus lesions and from synoviocytes in pannus lesions. Restriction fragment length polymorphism (RFLP) analysis was used to examine phosphoglycerate kinase 1 (PGK-1) gene patterns. Production of cytokines by these cells was also assessed.

RESULTS

All 13 RA synoviocytes exhibited colony formation, whereas none of the 4 OA synoviocytes did. This tendency was also seen with all of the concentrations of FCS examined, although growth varied in a dose-dependent manner. In contrast to OA synovial clones, cloned RA synoviocytes obtained from colonies exhibited a partial RFLP PGK-1 gene pattern, suggesting that the clones originated from monoclonal cells. Of note, 3 of 7 noncloned synoviocytes from pannus lesions exhibited a monoclonal pattern. Pannus cells produced high levels of transforming growth factor beta and platelet-derived growth factor.

CONCLUSION

These findings suggest that synoviocytes with a strong growth ability are present in the rheumatoid synovium, and that these cells expand monoclonally, particularly in pannus lesions.

Ribozyme-based gene cleavage approach to chronic arthritis associated with human T cell leukemia virus type I: induction of apoptosis in synoviocytes by ablation of HTLV-I tax protein

OBJECTIVE

To develop gene therapy for patients with human T cell leukemia virus type I (HTLV-I)-associated arthropathy (HAAP), we investigated the effects of ribozyme-mediated cleavage of HTLV-I tax/rex messenger RNA (mRNA) on synovial overgrowth.

METHODS

We introduced 2 hammerhead ribozymes targeted against HTLV-I tax/rex mRNA into synovial cells obtained from patients with HAAP and from patients with HTLV-I-negative rheumatoid arthritis (RA) and examined the ribozyme-mediated ablation of Tax expression. Using standard methods, we also determined the cells' ability to stop proliferating and to undergo apoptosis.

RESULTS

The ribozymes successfully cleaved tax/rex mRNA in HAAP patient synoviocytes. Both tax mRNA expression and Tax protein synthesis were inhibited significantly, resulting in inhibition of synovial cell growth and induction of apoptosis. In contrast, synovial cells from RA patients were not affected.

CONCLUSION

In vitro results suggest that ribozyme-mediated gene therapy can inhibit the growth of HTLV-I-infected synovial cells, which is maintained by Tax protein, in HTLV-I-related diseases including HAAP.

Up-regulation of iNOS mRNA expression and increased production of NO in human monoblast cell line, U937 transfected by HTLV-I tax gene

We investigated the mRNA expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO) in human T cell lymphotropic virus type I (HTLV-I) p40tax-transfected U937 cells, a human monoblast cell line. Transfection of HTLV-I p40tax U937 cells induced up-regulation of iNOS mRNA expression and subsequent NO production. Furthermore, interferon gamma (IFN-gamma) stimulation of HTLV-I p40tax-transfected U937 cells enhanced iNOS mRNA expression and NO production. The kinetics of iNOS mRNA expression and NO production indicated maximal effect at 24 and 48 hours, respectively, after culture with or without IFN-gamma. These findings suggest that HTLV-I p40tax can act as a transactivator of NO production in cells of Mo/M phi lineage. To what extent this mechanism may be involved in the pathogenesis of HTLV-I-associated diseases warrants further investigation.

Tenosynovial nodulosis in a patient infected with human T cell lymphotropic virus I

We describe a 45-year-old man who presented with multiple nodules along the tendons of the scapular region, the elbows, wrists, forearms, thighs, and ankles. The patient was a carrier of human T cell lymphotropic virus I (HTLV-I), which was probably transmitted from his mother; his mother also had polyarthritis. Histopathologically, the nodules consisted of numerous, small, fibrinoid masses. The synovium adjacent to the tendon sheath was hyperplastic, with fibrinoid necrosis mimicking rheumatoid synovium. However, synovitis was not present inside the adjacent joint. HTLV-I proviral DNA was detected in the cells of the nodule, in tenosynovial cells, and in peripheral blood lymphocytes, but not in skin fibroblasts. In situ reverse transcription assay showed a high quantity of tax/rex messenger RNA in the proliferating lining cells. Based on these features, we classified this case as an atypical manifestation of HTLV-I-associated arthropathy associated with fibrinoid nodules resulting from chronic tenosynovitis.

Arthritis syndromes associated with human T cell lymphotropic virus type I infection

Arthritis syndromes occur associated with HTLV-I infection both in the presence and in the absence of clinical ATL, and polyarthritis may be the presenting manifestation of HTLV-I-associated ATL. In both clinical settings, HTLV-I-infected T cells home to affected joints, and tax-transgenic mouse studies have suggested a pathogenic role for the HTLV-I tax gene in inducing synovial cell proliferation in HAA. Understanding the pathogenesis of rheumatoid arthritis-like arthritis syndromes that occur in the setting of HTLV-I infection should also provide insights into understanding of cellular and molecular mechanisms of synovial cell proliferation in HTLV-I-negative rheumatoid arthritis.

Rheumatoid arthritis as a bone marrow disorder

Both the concept of rheumatoid arthritis (RA) as an autoimmune process restricted to joints and the major role of T cells in its pathogenesis have been challenged in the literature. Fibroblastlike and macrophagelike synoviocytes play an important role in RA pannus, and these cells originate in or have their counterpart in bone marrow (BM). Yet the B cell autoimmunity characteristic of RA occurs early, and synovial tissue, like BM, favors the B cell response. Because BM is abnormal in RA, and because germinal centers are unique to RA synovium, RA could be regarded as a disorder of the microenvironments able to sustain B cell response. In fact, RA could even begin in BM, with its onset facilitated by stem cell abnormalities. Moreover, most viruses suspected of playing a role in RA share a BM tropism. This may explain why RA frequently overlaps with other autoimmune disorders and benign lymphoproliferations, such as large granular T lymphocytosis. Because remissions from RA have been reported after BM transplantation, careful studies of the rheumatological outcome of RA patients undergoing such therapeutic procedures are needed. Although RA is a complex process, it can be considered initially as a stem cell disorder requiring treatment similar to that administered to transplant patients. Animal models have provided convincing evidence for these assumptions.

Cytokine production by endothelial cells infected with human T cell lymphotropic virus type I

OBJECTIVE

To investigate the ability of human T cell lymphotropic virus type I (HTLV-I) to infect endothelial cells and induce cytokine production by these cells.

METHODS

Human umbilical vein endothelial cells (HUVEC) were cocultured with HTLV-I infected T cell line (MT-2 cells) or uninfected T cell line (CEM cells).

RESULTS

Following coculture with MT-2 cells, endothelial cells expressed HTLV-I specific core antigens. Endothelial cells cocultured with MT-2 cells produced significant amounts of several cytokines, including interleukin (IL)-1 alpha, IL-6, granulocyte colony stimulating factor (G-CSF), and granulocyte/macrophage colony stimulating factor (GM-CSF), compared with endothelial cells cocultured with CEM cells. Coculturing of endothelial cells with MT-2 and CEM cells failed to produce detectable amounts of IL-1 beta and tumour necrosis factor alpha (TNF-alpha). The production of cytokines by endothelial cells cocultured with MT-2 cells was more persistent than that by endothelial cells cocultured with CEM cells after several passages. Furthermore, the production was blocked by cocultivation of endothelial cells and MT-2 cells using the Millicell system. Finally, after cocultivation of endothelial cells and MT-2 cells, endothelial cells positive for HTLV-I antigen were stained by anti-GM-CSF antibody.

CONCLUSIONS

HTLV-I can infect endothelial cells, resulting in their active production of several cytokines, such as IL-1 alpha, IL-6, G-CSF, and GM-CSF. These findings strongly suggest that the excess production of these cytokines by HTLV-I infected endothelial cells may be involved in the pathogenesis of HTLV-I associated inflammatory diseases.

Human T lymphotropic virus type I in arthropathy and autoimmune disorders

The progressive nature of the disease and the persistent inflammation affecting various organs are common features of idiopathic autoimmune disorders of unknown etiology. Therefore, the HTLV-I-associated disorders described in the present review are outstandingly important models for our understanding of the pathologic mechanisms of organ-specific immune disorders. HTLV-I arthropathy is characterized by chronic inflammatory and proliferative synovitis with lymphoid follicles and pannus formation in the affected joints, indistinguishable from the findings in idiopathic RA. The presence of the tax gene in HTLV-I-negative SS patients suggests that it is responsible for the exocrine gland abnormality, characterized by extensive lymphoproliferative epithelial lesions. Furthermore, the pulmonary lesions of HTLV-I bronchopneumonopathy are similar to those of idiopathic interstitial pneumonitis. Based on these observations, the clinical findings associated with the immunologic abnormalities in HTLV-I-infected patients provide us with valuable information for understanding the pathogenetic mechanisms of chronic inflammatory conditions associated with immune regulatory disorders. Although the clinical and pathologic features of the 2 common HTLV-I-associated disorders, ATL and HAM/TSP, have been well characterized and are clearly distinguishable from those of the idiopathic forms of these disorders, other HTLV-I-related autoimmune diseases, e.g., arthropathy, SS, or bronchopneumonopathy, are clinically indistinguishable from the idiopathic forms of the diseases. Such similarity may serve as a clue to the pathogenetic mechanisms of idiopathic autoimmune disorders.

The potential roles of endogenous retroviruses in autoimmunity

Endogenous retroviruses (ERVs) are estimated to comprise up to 1% of human DNA. While the genome of many ERVs is interrupted by termination codons, deletions or frame shift mutations, some ERVs are transcriptionally active and recent studies reveal protein expression or particle formation by human ERVs. ERVs have been implicated as aetiological agents of autoimmune disease, because of their structural and sequence similarities to exogenous retroviruses associated with immune dysregulation and their tissue-specific or differentiation-dependent expression. In fact, retrovirus-like particles distinct from those of known exogenous retroviruses and immune responses to ERV proteins have been observed in autoimmune disease. Quantitatively or structurally aberrant expression of normally cryptic ERVs, induced by environmental or endogenous factors, could initiate autoimmunity through direct or indirect mechanisms. ERVs may lead to immune dysregulation as insertional mutagens or cis-regulatory elements of cellular genes involved in immune function. ERVs may also encode elements like tax in human T-lymphotrophic virus type I (HTLV-I) or tat in human immunodeficiency virus-I (HIV-I) that are capable of transactivating cellular genes. More directly, human ERV gene products themselves may be immunologically active, by analogy with the superantigen activity in the long terminal repeat (LTR) of mouse mammary tumour viruses (MMTV) and the non-specific immunosuppressive activity in mammalian type C retrovirus env protein. Alternatively, increased expression of an ERV protein, or expression of a novel ERV protein not expressed in the thymus during acquisition of immune tolerance, may lead to its perception as a neoantigen. Paraneoplastic syndromes raise the possibility that novel ERV-encoded epitopes expressed by a tumour elicit immunity to cross-reactive epitopes in normal tissues. Recombination events between different but related ERVs, to whose products the host is immunologically tolerant, may also generate new antigenic determinants. Frequently reported humoral immunity to exogenous retrovirus proteins in autoimmune disease could be elicited by cross-reactive ERV proteins. A review of the evidence implicating ERVs in immune dysfunction leads to the conclusion that direct molecular studies are likely to establish a pathogenic role for ERVs in autoimmune disease.

Acquired immune deficiency syndrome caused by hyperimmunity

Normal immunocytes including T and B cells are equilibrated by a reciprocal attacking mechanism called a network. Continuous disequilibrium of this network results in general immunodeficiency with oligo- and polyclonal hyperimmunity, for example, T-cell activation due to spontaneous reticuloendotheliosis, paraneoplastic autoimmune syndromes, and human immunodeficiency virus infection. In these disorders, reciprocal self-reactivity, including autologous graft-versus-host reaction, plays a role in the immunodeficiency. A priori self-targeting immunity is a key mechanism to explain autoimmunity in the acquired immunodeficiency syndrome. In the treatment of the immunodeficiency due to hyperimmunity, I propose immunological suppression by agents and reconstitution of the network by bone-marrow transplantation.

High seroprevalence of anti-HTLV-I antibody in rheumatoid arthritis

OBJECTIVE

To investigate the association between human T lymphotropic virus type I (HTLV-I) infection and rheumatoid arthritis (RA) in Nagasaki, an area highly endemic for HTLV-I infection.

METHODS

Sera from 113 female patients with RA and 19,796 female blood donors were screened for anti-HTLV-I antibodies with a gelatin particle agglutination kit and confirmed using an immunoblotting kits.

RESULTS

The age-adjusted summary odds ratio of HTLV-I infection among RA patients, as compared with blood donors, was 2.8 (95% confidence interval [95% CI] 1.8-4.6). The etiologic fraction, i.e., the proportion of RA in the study population that is attributable to HTLV-I infection, was estimated to be 13.2% (95% CI 5.1-21.2). There was no significant difference in the clinical and laboratory findings between HTLV-I- infected and HTLV-I-uninfected RA patients.

CONCLUSION

These epidemiologic findings support the idea that HTLV-I infection is a risk factor for RA, and suggest that approximately 13 % of the cases of RA in females living in Nagasaki are associated with HTLV-I infection.

Activation of transcription factor NF-kappa B in human synovial cells in response to tumor necrosis factor alpha

OBJECTIVE

To examine whether nuclear factor kappaB (NF-kappaB) is activated in cultured synovial cells in response to tumor necrosis factor alpha (TNFalpha) and to investigate the correlation between NF-kappaB activation and synovial cell proliferation.

METHODS

Activation of NF-kappaB was detected by electrophoretic mobility shift assay. The transcription of several NF-kappaB-dependent genes was evaluated by reverse transcriptase polymerase chain reaction and transient expression assay using human immunodeficiency virus-long terminal repeat chloramphenicol acetyltransferase. Proliferative activity was determined by measurement of 3H-thymidine incorporation.

RESULTS

Stimulation of synovial cells with TNFalpha activated NF-kappaB and subsequent transcription of several genes. Treatment of synovial cells with N-acetyl-L-cysteine (NAC), an antioxidant agent, inhibited TNFalpha-induced NF-kappaB activation and transcription. Moreover, NAC also inhibited synovial cell proliferation induced by TNFalpha.

CONCLUSION

Our results suggest that NF-kappaB plays a pivotal role in synovial cell activation by TNFalpha. Thus, suppression of NF-kappaB could be a potential therapeutic modality for synovitis such as that of rheumatoid arthritis.

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.

HTLV-I arthropathy and Sjögren syndrome

Human T-cell lymphotropic virus type I (HTLV-I) was initially detected as the causative agent of adult T-cell leukemia (ATL). However, recent studies have revealed that HTLV-I may disrupt the immune system and lead to the development of rheumatoid arthritis and Sjögren syndrome. A current study in our laboratory has revealed that HTLV-I tax gene, known as the transregulatory gene, contributes not only to the induction of synovial cell hyperplasia but also the immune response, both in vivo and in vitro. In this report, the role of HTLV-I in the pathogenesis of chronic destructive arthropathy and Sjögren syndrome is discussed.

HTLV-I-induced T-cell activation

Infection by the human T-cell lymphotropic virus type I (HTLV-I) causes T-cell activation by at least two separate mechanisms. One mechanism involves activation of the T cells harboring the virus and is exemplified by in vivo infected nonimmortalized T-cell clones that display a prolonged state of activation. This HTLV-I-induced T-cell activation is inhibited by rapamycin, a drug that inhibits p70 S6-kinase and blocks cell cycle in G1, but is not inhibited by FK506 or cyclosporin A, both of which inhibit interleukin-2 (IL-2) production. The phenotype of this pathway is consistent with an hyperactive IL-2R pathway or CD28 pathway, indicating that HTLV-I may contribute a costimulatory signal to the infected T cell. As a separate mechanism, HTLV-I-infected T cells can induce activation of uninfected T cells via T-T-cell interaction mediated by the LFA-3-CD2 pathway. This may induce IL-2 production from the uninfected T cells, leading to a more generalized activation of the immune system that potentially could provide a basis for some of the diseases associated with HTLV-I. Moreover, this THTLV-I-T-cell interaction could explain the spontaneous proliferation observed in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis.

Apoptosis and functional Fas antigen in rheumatoid arthritis synoviocytes

OBJECTIVE

To determine whether apoptosis occurs in rheumatoid arthritis (RA) synoviocytes, and if this phenomenon is dependent on the Fas/Apo-1 pathway.

METHODS

Apoptotic change in vivo was examined in RA synovial cells by several standard methods. The ability of cells to undergo Fas-induced apoptosis was determined in vitro.

RESULTS

Typical apoptotic change was demonstrated in RA synovial cells by each method. Anti-Fas antibody induced apoptotic synovial cell death in vitro.

CONCLUSION

This is the first reported study to demonstrate apoptosis in RA synovial cells. The findings indicate that rheumatoid synoviocytes undergo Fas-mediated apoptosis.

Limited TCR V beta usage of infiltrating T cells in synovial tissues from patients with HTLV-I associated arthropathy

Human T cell lymphotropic virus type-I (HTLV-I) is the etiologic agent of adult T cell leukemia/lymphoma and recently has also been suggested to be involved in chronic arthritis. The synovia of patients with rheumatoid arthritis (RA) contains activated T lymphocytes, with a restricted expression of T cell receptor (TCR) variable (V) beta gene segments. To characterize the T-cell populations of RA among HTLV-I carriers and noncarriers, we performed the immunohistochemical staining of CD4 and CDB, as well as a reverse transcription polymerase chain reaction (RT-PCR) to estimate the proportion of TCR beta RNA containing any particular V elements on the synovial specimens. In all but one HTLV-I carrier, the proviral DNA and/or RNA expression of HTLV-I was detected in the synovium. The CD4-positive cells proliferated markedly in the HTLV-I carriers compared with the noncarriers. In contrast to mononuclear cells in the peripheral blood, synovial T cells expressed only a few V beta transcripts, and no definite difference was observed between the carriers and the noncarriers. These results suggest that a common major antigen associated with the pathogenesis of RA may thus selectively interact with the V beta component of the TCR. Using RT-PCR, we studied the expression of the recombination-activating gene-1 (RAG-1), which was used in the V(D)J recombination of immunoglobulin and TCR genes. In all cases, RAG-1 was transcripted. The results supported the possibility that the extrathymic development of the selected TCR V beta T cells occurred in the synovia.

Expression of endogenous retroviruses, ERV3 and lambda 4-1, in synovial tissues from patients with rheumatoid arthritis

We addressed the question of whether or not expression of human endogenous retroviruses (ERV), ERV3 and lambda 4-1, is related to the pathogenesis of rheumatoid arthritis (RA). In genomic Southern hybridization, there were no significant differences between RA patients and healthy volunteers with regard to frequencies of restriction fragment length polymorphism (RFLP) patterns, for either ERV3 or lambda 4-1. By Northern blot analysis using fresh synovial tissues, cultured synovial cells, and peripheral blood mononuclear cells (PBMC) from patients with RA, we noted two molecular species of ERV3 mRNAs of 3.5 kb and 9.0 kb sizes, and one single molecular species of lambda 4-1 mRNAs of 4.2 kb size. The expression was detected not only in RA patients but also in synovial cells from osteoarthritis (OA) as a non-RA control and PBMC from healthy volunteers, and was not related to RA activities or treatments. Although ERV3 and lambda 4-1 expression may not be directly associated with the pathogenic pathway of RA, the possibility exists that human ERV may have a causative role in autoimmune diseases, including RA. We also examined the effect of cytokines on the transcriptional regulation of ERV3. Although the level of ERV3 expression in cultured synovial cells did not change with IL-1 beta treatment, the level for cultured proximal tubular epithelial cells (hKEC) was up-regulated.

Retroviruses and autoimmune rheumatic diseases

In autoimmune rheumatic diseases, retroviruses have been repeatedly discussed as important etiologic factors. However, despite a considerable amount of indirect evidence that retroviruses might indeed be involved in triggering or perpetuating autoimmune rheumatic diseases, clear cut direct evidence is still missing. Studies on arthropathies associated with HIV-1 or HTLV-1 infection as well as new experimental animal models like the Tax transgene mice and new data from the MLR/lpr mouse model might help to answer the questions how and by what mechanisms retroviral infection may lead to autoimmune rheumatic diseases. From data obtained in the MLR/lpr mouse it seems obvious that a potential link of retroviruses, apoptosis and autogenes to autoimmune diseases opens exciting new approaches to the study of rheumatic disease pathogenesis.

Expression of human T lymphotropic virus type 1 (HTLV-1) tax/rex gene in fresh bronchoalveolar lavage cells of HTLV-1-infected individuals

Accumulating evidence has suggested the involvement of HTLV-1 in the inflammatory lesions of various organs, including the lung. However, the causal relationship between HTLV-1 and inflammatory responses in the organs remains to be elucidated. In order to evaluate the expression of HTLV-1 and its effects in the lung, we examined the expression of mRNA for the HTLV-1 tax/rex gene in fresh bronchoalveolar lavage cells (BALC) and peripheral blood mononuclear cells (PBMC) of 23 seropositive individuals, including six patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), by use of an improved method of reverse transcription-polymerase chain reaction (RT-PCR). The tax/rex mRNA was more frequently detected in BALC than in PBMC. All the HAM/TSP patients and eight of 17 carriers without neurological symptoms showed the expression of tax/rex mRNA in the BALC. IgM class antibodies to HTLV-1 were preferentially detected in sera of the tax/rex mRNA-positive individuals. The detection of tax/rex mRNA correlated closely with the presence of lymphocytosis accompanied by an elevated proportion of IL-2 receptor-bearing T cells in the BALC. Our findings indicate the crucial role of viral expression in the inflammatory response in the lung in HTLV-1-infected individuals.