Toshiaki Sugaya

Immunological Hyperresponsiveness in HTLV-I LTR-env-pX Transgenic Rats: A Prototype Animal Model for Collagen Vascular and HTLV-I-Related Inflammatory Diseases

We have earlier reported that diverse collagen vascular diseases, including arthritis, arteritis, thrombosis, myocarditis, myositis, sialo-/dacryoadenitis and dermatitis develop with the advent of autoantibodies in transgenic rats carrying the LTR-env-pX gene of human T lymphocyte virus type I (LTR-env-pX rats). To clarify the pathogenesis of these collagen vascular diseases, immunological features of LTR-env-pX rats were examined. In LTR-env-pX rats affected with these diseases, expression of CD80/86 on both tissue-infiltrating and peripheral T cells increased, compared with findings in non-transgenic rats with experimental inflammatory diseases. CD80/86 was also upregulated on peripheral T cells in LTR-env-pX rats prior to the development of diseases. Lymphocytes from LTR-env-pX rats showed an increase in autologous proliferation and were hyperreactive against several mitogens, including concanavalin A, immobilized anti-CD3 antibodies, and superantigens in vitro. Antigen-specific immune response was also enhanced in LTR-env-pX rats. The collective evidence indicates that lymphocytes of LTR-env-pX rats constitutively express surface molecules related to T cell activation and are immunologically hyperresponsive. Bone marrow cell transfer from LTR-env-pX rats to lethally irradiated non-transgenic rats revealed that these immunologically pre-activated and hyperresponsive lymphocytes play a critical role in the pathogenesis of several collagen vascular diseases, especially of dermatitis in LTR-env-pX rats.

Procalcitonin is a specific marker for detecting bacterial infection in patients with rheumatoid arthritis.

Objective. Rheumatoid arthritis (RA) is a chronic inflammatory disease accompanied by many complications, and serious infections are associated with many of the advanced therapeutics used to treat it. We assessed serum procalcitonin (PCT) levels to distinguish bacterial infection from other complications in patients with RA. Methods. One hundred eighteen patients experiencing an RA flare, noninfectious complication of RA or its treatment, nonbacterial infection, or bacterial infection were studied. Serum PCT concentrations were determined with a chemiluminescent enzyme immunoassay. Results. All patients experiencing an RA flare showed negative PCT levels (≤ 0.1 ng/ml; n = 18). The PCT level was higher in the bacterial infection group (25.8% had levels ≥ 0.5 ng/ml) than in the other 3 groups (0.0–4.3% had levels ≥ 0.5 ng/ml) and the difference was significant among groups (p = 0.003). Conversely, no statistically significant difference was observed among the groups with C-reactive protein (CRP) concentration ≥ 0.3 mg/dl (p = 0.513), white blood cell (WBC) count > 8500/mm3 (p = 0.053), or erythrocyte sedimentation rate (ESR) > 15 mm/h (p = 0.328). The OR of high PCT level (≥ 0.5 ng/ml) for detection of bacterial infection was 19.13 (95% CI 2.44–149.78, p = 0.005). Specificity and positive likelihood ratio of PCT ≥ 0.5 ng/ml were highest (98.2% and 14.33, respectively) for detection of bacterial infection, although the sensitivity was low (25.8%). Conclusion. Serum PCT level is a more specific marker for detection of bacterial infection than either CRP, ESR, or WBC count in patients with RA. High PCT levels (≥ 0.5 ng/ml) strongly suggest bacterial infection. However, PCT < 0.5 ng/ml, even if < 0.2 ng/ml, does not rule out bacterial infection and physicians should treat appropriately.

A novel animal model of thymic tumour: development of epithelial thymoma in transgenic rats carrying human T lymphocyte virus type I pX gene.

The pX region encodes a major product of human T lymphocyte virus type I (HTLV‐I) that has been implicated previously in tumour formation. To investigate the pathogenesis of pX gene in lymphoid tissues, we established a series of novel transgenic rats carrying the pX gene under the control of a rat lymphocyte‐specific protein tyrosine kinase (p56lck) proximal promoter.

The Role of the Thymus in Development of Necrotizing Arteritis in Transgenic Rats Carrying the env-pX Gene of Human T-Cell Leukemia Virus Type-I

Necrotizing arteritis mimicking polyarteritis nodosa occurred in transgenic rats carrying the env-pX gene of human T-cell leukemia virus type I. To investigate the pathogenesis of necrotizing arteritis in these rats (env-pX rats), adoptive transfers of spleen cells and bone marrow cells were done from env-pX rats before they developed arteritis to nontransgenic rats. Necrotizing arteritis occurred in lethally irradiated nontransgenic rats reconstituted by env-pX spleen cells, thus indicating that the env-pX transgene in affected vessels may not be essential for the development of arteritis. In contrast, arteritis was not induced in nontransgenic recipients by adoptive transfers of env-pX bone marrow cells, which suggested that T cells derived from the env-pX thymus may play a role in the development of arteritis. To clarify if the process of differentiation of T cells in the env-pX thymus is crucial to develop necrotizing arteritis, reciprocal exchange of thymus frameworks was done between env-pX and nontransgenic rats. Necrotizing arteritis occurred in nontransgenic rats with an env-pX thymus framework, whereas development of arteritis was suppressed in env-pX rats in which the thymus framework was replaced with a nontransgenic one. This collective evidence shows that the thymus is directly associated with the development of necrotizing arteritis in env-pX rats.

Functional alteration of peripheral CD25(+)CD4(+)immunoregulatory T cells in a transgenic rat model of autoimmune diseases.

Transgenic rats carrying the env-pX gene of human T cell leukemia virus type-I (env-pX rats) develop various collagen vascular diseases. Since autoantibodies are present in their sera, env-pX rats are considered to be a prototype model for autoimmune diseases. Adoptive transfers of spleen cells from syngenic non-transgenic rats decreased the incidence of diseases in env-pX rats, thus suggesting that normal spleen contains cells, which suppress autoimmune diseases. Murine peripheral CD25(+)CD4(+)T cells play roles in maintaining immunological self-tolerance. To examine if alterations of immunoregulatory cells may be evident in env-pX rats, quantitative and qualitative analyses of splenic CD25(+)CD4(+)T cells were done before these rats developed autoimmune diseases. Env-pX and non-transgenic rats had equivalent number of CD25(+)CD4(+)T cells. However, CD25(+)CD4(+)T cells from env-pX rats did not suppress proliferation of T cells stimulated by anti-CD3 antibodies (Ab) in vitro, whereas those from non-transgenic rats did. Additionally, env-pX CD25(+)CD4(+)T cells showed autologous and anti-CD3 Ab-mediated proliferation, in contrast to the anergic features in non-transgenic rats. These findings appear to be the first evidence that CD25(+)CD4(+)immunoregulatory T cells are altered in animal models, which naturally develop autoimmune diseases.

Tissue specific high level expression of a full length human endogenous retrovirus genome transgene, HERV-R, under control of its own promoter in rats.

Human endogenous retrovirus-R (HERV-R) is one of a full length HERV with a long open reading frame in the env region. The env transcripts are expressed in various human tissues. To investigate the biological role of HERV-R in vivo, we established two lines of transgenic rats carrying a full sequence of HERV-R under control of its own long terminal repeat (LTR) promoter. One line with tandem integration of multiple copies of the transgene expressed HERV-R mRNA in various organs with different expression levels and relatively higher in Harderian and submandibular salivary glands. In another line, the transgene was integrated as a single copy in a haploid and the expression was detected only in Harderian and submandibular salivary glands. In the placenta, one of the tissues with high levels of the HERV-R expression in humans, the transcription was evident starting the 12th day after gestation. A rabbit antiserum against synthetic peptides corresponding with the HERV-R env gene sequence led to detection of an 85 kDa product as a glycoprotein in the Harderian glands. While no pathological significance was observed in either line, the transgenic rat may prove to be a suitable model for analyzing the role of HERV-R function in vivo.

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.