DAB389IL-2 recombinant fusion toxin effect on lymphocyte- and macrophage-producing cytokine subpopulation cells in experimentally induced demyelinating disease in mice.

CONTEXT: We have reported previously that DAB389IL-2 recombinant fusion toxin targets IL-2R bearing CD4+ cells, and suppresses demyelinating disease in acute (A) - and chronic (C) - experimental autoimmune encephalomyelitis (EAE) animal models of multiple sclerosis. OBJECTIVES: The present study was undertaken to investigate the effect of DAB389IL-2 treatment on various cytokine-secreting cell populations in A-EAE and C-EAE mice. MATERIALS AND METHODS: The effects of DAB389IL-2 at doses of 200-, 800-, or 1600 kU administered i.v. on days 11-13 and 15 on the clinical score and cytokine-secreting cell populations were examined using flow cytometry. RESULTS: C-EAE mice treated with 1600kU DAB389IL-2, but not A-EAE mice treated with 800 kU had significantly reduced disease. The CD3+CD25+ sub-population in spleens and spinal cords of A-EAE mice treated with 800 kU DAB389IL-2 a was increased, whereas in C-EAE mice treated with 1600 kU this population was increased. DAB389IL-2 treatment reduced CD3+CD4+, CD3+CD8+, CD4+CD8+, CD3+IL-2+, CD3+IFN-γ+ and CD3+TNF-α+ T cell subpopulations in the spinal cord in A-EAE, and C-EAE mice on day 16. CD11b+ macrophages that were IL-2-, IFN-γ-, and TNF-α- positive were reduced in A-EAE mice. DAB389IL-2 treatment reduced CD19+ B-cells positive for IL-2 or CD11b+ in the spinal cord in acute and chronic disease. DAB389IL-2 treatment also reduced lymph node CD3+CD8+, CD4+CD8+, CD3+CD25+ populations on day 16, and lymph node CD3+IL-10+ and peripheral blood CD3+CD25+ populations on day 24. DISCUSSION AND CONCLUSIONS: Our study demonstrates that DAB389IL-2 fusion toxin suppresses EAE in a dose-dependent manner, and alters inflammatory cell sub-populations during disease development.

DAB389IL-2 suppresses autoimmune inflammation in the CNS and inhibits T cell-mediated lysis of glial target cells.

In multiple sclerosis (MS) and its rodent model, experimental autoimmune encephalomyelitis (EAE), activated CD4(+) T cells with upregulated IL-2R mediate inflammation and demyelination in the central nervous system (CNS). DAB(389)IL-2, a chimeric fusion protein of IL-2 and diphtheria toxin, inhibits human and rodent IL-2 activated T cells that express the high affinity interleukin-2 receptor. In the present study, DAB(389)IL-2 was used to treat rats with EAE. We wanted to investigate the possibility that DAB(389)IL-2 could prevent tissue destruction within the CNS. We used a suboptimal dose of DAB(389)IL-2 that allowed substantial transmigration of inflammatory cells across the blood-brain barrier. DAB(389)IL-2 inhibited infiltration of CD4(+), CD8(+), CD25(+) and TCR αß(+) associated mononuclear cells and inflammatory macrophages in the spinal cord on day 13 post-immunization, at the peak of disease. Gene expression study showed that DAB(389)IL-2 treatment suppressed TNF-α and IFN-γ as well as IL-10 cytokine gene expression in the spinal cord of rats with EAE on day 13. DAB(389)IL-2 in vitro treatment suppressed cytotoxicity of MBP-activated T cells from rats with EAE against oligodendrocytes in culture by 66%. Astrocytes were less targeted by MBP activated T cells in vitro. This study suggests that DAB(389)IL-2 directly targets CD4(+) and CD25(+) (IL-2R) T cells and effector T cell function and also indirectly suppresses the activation of macrophage CD169(+) (ED3(+)) and microglia CD11b/c (OX42(+)) populations in the CNS.

Effect of millimeter waves and cyclophosphamide on cytokine regulation.

We have reported previously that millimeter waves (MMWs) protect T-cell functions from the toxic side effects of cyclophosphamide (CPA), an anticancer drug. Since the effect of MMWs has been reported to be mediated by endogenous opioids, the present study was undertaken to investigate the role of endogenous opioids in protection of T-cell functions by MMWs. The effect of MMWs (42.2 GHz, incident power density = 38 mW/cm²) was studied on CPA-induced suppression of cytokine release by T cells in the presence of selective opioid receptor antagonists (ORA). Production of cytokines was measured in CD4 T cells isolated from splenocytes. Treatment of mice with CPA suppressed the formation of Th1 cytokines (TNF-α, IFN-γ, and IL-2), shifting the overall balance toward Th2 (IL-4 and IL-5). MMW irradiation of CPA-treated groups up-regulated the production of Th1 cytokines suppressed by CPA. Treatment of the CPA+MMW group with selective kappa (κ) ORA further potentiated this effect of MMWs on Th1 cytokine production, whereas treatment with µ or δ ORA increased the imbalance of cytokine production in the Th2 direction. These results provide further evidence that endogenous opioids are involved in immunomodulation by MMWs.

Suppression of murine experimental autoimmune encephalomyelitis by interleukin-2 receptor targeted fusion toxin, DAB(389)IL-2.

Previously we have shown that DAB(389)IL-2, a recombinant fusion toxin targeting IL-2R bearing cells, suppressed disease in the rat experimental autoimmune encephalomyelitis (EAE) model of acute multiple sclerosis (MS). Our present study demonstrates that DAB(389)IL-2 can also effectively suppress acute (A)-EAE, relapsing (R)-EAE and chronic (C)-EAE in mouse demyelinating models. DAB(389)IL-2 significantly suppressed mitogenic proliferation of spleen cells while mutant fusion proteins DA(glu53)B(389)IL-2 and DAB(389)IL-2(8-10) did not. EAE was successfully suppressed when DAB(389)IL-2 was administered in various regimens between days 1 and 15 post immunization in all three models. CD4(+)IL-2R(+) cells were reduced in the spleen but not in the lymph nodes of DAB(389)IL-2-treated mice during A-EAE while the number of CD8(+) cells was unchanged. DAB(389)IL-2 also significantly reduced the number of CD4(+), CD8(+), CD25(+), TCRgammadelta(+) phenotype and CD11b(+) macrophages/microglia within spinal cord lesions. These data strongly suggest that DAB(389)IL-2 specifically targeted myelin protein-activated CD4(+) T cells and strengthens the argument for the use of DAB(389)IL-2 in treatment strategies for MS.

Effect of DAB(389)IL-2 immunotoxin on the course of experimental autoimmune encephalomyelitis in Lewis rats.

Activated T cells express the high affinity interleukin 2 receptor (IL-2R also CD25) that binds interleukin 2 (IL-2) and transduces signals important for the proliferation and survival of these cells. We investigated the effect of the genetically engineered immunotoxin DAB(389)IL-2 on experimental autoimmune encephalomyelitis (EAE), an autoimmune disease of the central nervous system (CNS) mediated by activated myelin-reactive T cells. EAE is the most commonly used animal model of the human disease multiple sclerosis (MS). DAB(389)IL-2 is a recombinant fusion product made of a portion of diphtheria toxin, which contains binding and translocation components of the toxin linked to IL-2. The diphtheria toxin targets and kills cells expressing the high affinity IL-2 receptor and has been successfully used in several autoimmune and neoplastic conditions. We observed a significant suppression of guinea-pig spinal cord homogenate (gpSCH)-MBP induced active EAE in Lewis rats at 2 x 1,600 kU of DAB(389)IL-2 given on days 7 and 9 post-immunization and complete suppression with the same dose on days 7, 8 and 9 or 7, 8, 9 and 10 after immunization during the active disease period. There were reduced mononuclear cell infiltrates of CD4(+), CD8(+), CD25(+) and alphabetaTCR(+) T cells in the spinal cord of treated rats. However, treatment at day 11 or 12 post-immunization led to severe, fatal disease. The toxin added to cultures in vitro or injected in vivo suppressed antigen- and mitogen-induced T cell proliferation. DAB(389)IL-2 treatment in vivo or exposure of encephalitogenic T cells in vitro prior to transfer did have a significant inhibitory effect on adoptive transfer EAE. Our data demonstrate that DAB(389)IL-2 immunotoxin can suppress active and passive EAE if applied at specific, early time points, but can have negative consequences at later time points.

The fork head transcription factor FKTF-1b from Strongyloides stercoralis restores DAF-16 developmental function to mutant Caenorhabditis elegans.

The purpose of this study was to determine whether Strongyloides stercoralis FKTF-1, a transcription factor of the FOXO/FKH family and the likely output of insulin/IGF signal transduction in that parasite, has the same or similar developmental regulatory capabilities as DAF-16, its structural ortholog in Caenorhabditis elegans. To this end, both splice variants of the fktf-1 message were expressed under the control of the daf-16alpha promoter in C. elegans carrying loss of function mutations in both daf-2 (the insulin/IGF receptor kinase) and daf-16. Under well-fed culture conditions the majority (91%) of untransformed daf-2; daf-16 double mutants developed via the continuous reproductive cycle, whereas under the same conditions 100% of daf-2 single mutants formed dauers. Transgenic daf-2; daf-16 individuals expressing fktf-1b showed a reversal of the double mutant phenotype with 75% of the population forming dauers under well-fed conditions. This phenotype was even more pronounced than that of daf-2; daf-16 mutants transformed with a homologous rescuing construct, daf-16alpha::daf-16a (56% dauers under well fed conditions), indicating that S. stercoralis fktf-1b can almost fully rescue loss-of-function mutants in C. elegans daf-16. By contrast, daf-2; daf-16 mutants expressing S. stercoralis fktf-1a, encoding the second splice variant of FKTF-1, showed a predominantly continuous pattern of development identical to that of the parental double mutant stock. This indicates that, unlike FKTF-1b, the S. stercoralis transcription factor FKTF-1a cannot trigger the shift to dauer-specific gene expression in C. elegans.

Skeletal muscle myosin is the autoantigen for experimental autoimmune myositis.

Experimental autoimmune myositis (EAM) is a rodent model for human inflammatory muscle disease (IMD). It can be induced by immunization of rodents with skeletal muscle homogenate and adjuvant. The specific myositogenic autoantigen has not been clearly identified although some evidence points to skeletal muscle myosin. In this report we strengthen this evidence, showing that Lewis rats immunized with purified skeletal muscle myosin develop EAM with the same pattern and severity as EAM induced by whole rabbit skeletal muscle homogenate (WRM). Multiple inflammatory lesions are detected histopathologically in the biceps, quadriceps, and gastrocnemius muscles. Myosin-reactive T cells from animals immunized either with myosin or with WRM have similar patterns of antigen-induced proliferation. The results show that myosin, a component of skeletal muscle, is at least one autoantigen in EAM.