Purification and Refolding of Recombinant Human IGF II from Silkworms Infected with RecombinantBombyx moriNuclear Polyhedrosis Virus

We have reported that insulin-like growth factor II (IGF II) was produced as a fusion protein in Bombyx mori (silkworm) larval bodies infected with recombinant B. mori nuclear polyhedrosis virus [J. Gen. Virol., 68, 2599-2606 (1987)]. In this study, the purification of IGF II from the infected silkworms is reported. The fusion protein was extracted with 6.0 M guanidine-HCl from the infected larval bodies homogenized in water. The use of organic solvents to remove the impurities, such as lipid derived from the larval bodies, was a very effective method of purification. IGF II was released from the partially purified fusion protein by treatment with CNBr, purified by HPLC, and refolded by air-oxidization. Refolded IGF II had an identical primary structure including disulfide bonds and showed identical thymidine uptake stimulation activity with human IGF II. Furthermore, protein disulfide-isomerase was shown to be able to refold scrambled IGF II rapidly.

Establishment and characterization of tracheal epithelial cell lines, TM01 and TM02-3, from transgenic mice bearing temperature-sensitive simian virus 40 large T-antigen gene

Murine tracheal epithelial cell lines, TM01 and TM02-3, were established from a primary culture of tracheal cells of adult transgenic mice bearing a temperature-sensitive simian virus (SV40) large T-antigen gene. Both TM01 and TM02-3 cells, which grew until confluent monolayers were formed, maintained tight contact with neighboring cells, and retained the characteristics of epithelial cells with microvilli on the surface. These cells grew at a permissive temperature (33 degrees C), but did not at a nonpermissive temperature (39 degrees C), indicating that TM01 and TM02-3 cells undergo temperature-sensitive growth. Large T-antigen was expressed only in the nuclei at 33 degrees C. Sepharose CL-4B column chromatography using a 14C-glucosamine hydrochloride, indicating that both cells produced high molecular weight glycoconjugates, and suggesting that these cells may originate from mucus-producing cells. TM01 cells expressed intercellular adhesion molecular-1 (ICAM-1) in both unstimulated and stimulated (1,000 U/ml tumor necrosis factor-alpha and 500 U/ml interferon-gamma) conditions, whereas TM02-3 cells expressed ICAM-1 only under stimulated conditions. We conclude that these cell lines may serve as a useful model to study the tracheal cell functions under defined in vitro conditions.

Abrogation of bronchial eosinophilic inflammation and airway hyperreactivity in signal transducers and activators of transcription (STAT)6-deficient mice

Signal transducers and activators of transcription 6 (STAT6) is essential for interleukin 4-mediated responses, including class switching to IgE and induction of type 2 T helper cells. To investigate the role of STAT6 in allergic asthma in vivo, we developed a murine model of allergen-induced airway inflammation. Repeated exposure of actively immunized C57BL/6 mice to ovalbumin (OVA) aerosol increased the level of serum IgE, the number of eosinophils in bronchoalveolar lavage (BAL) fluid, and airway reactivity. Histological analysis revealed peribronchial inflammation with pulmonary eosinophilia in OVA-treated mice. In STAT6-deficient (STAT6-/-) C57BL/6 mice treated in the same fashion, there were no eosinophilia in BAL and significantly less peribronchial inflammation than in wild-type mice. Moreover STAT6-/- mice had much less airway reactivity than wild-type mice. These findings suggest that STAT6 plays a crucial role in the pathogenesis of allergen-induced airway inflammation.

The xid mutation plays an important role in delayed development of murine acquired immunodeficiency syndrome

Infection of C57BL/6 mice with LP-BM5 murine leukemia virus (MuLV) leads to the development of murine acquired immunodeficiency syndrome (MAIDS) characterized by abnormal lymphoproliferation, hypergammaglobulinemia and severe immunodeficiency. Progression of MAIDS is delayed in X chromosome-linked immunodeficient (XID) mice, which have an abnormality of Bruton's tyrosine kinase (Btk) and lack functionally mature B cells including CD5+ B cells. In this study, we report the following four major findings. (i) Susceptibility to disease induction is not reconstituted by transfer of CD5+ B cells to XID mice. (ii) Spleen cells from asymptomatic XID mice are able to transmit MAIDS to wild-type mice. (iii) MAIDS can be transmitted to XID mice with the transfer of B cells, but not T cells, from C57BL/6 mice with MAIDS. (iv) Cells which undergo massive lymphoproliferation in XID mice with MAIDS by cell transfer are of host origin, but are not from the donor. We suggest from these results that a B cell subpopulation that is impaired in XID mice plays an important role in the initiation of MAIDS.

An IFN-gamma-dependent pathway plays a critical role in the pathogenesis of murine immunodeficiency syndrome induced by LP-BM5 murine leukemia virus

The murine acquired immunodeficiency syndrome (MAIDS) caused by a defective murine leukemia virus produces severe immunodeficiency with abnormal lymphoproliferation and hypergammaglobulinemia. The presence of both CD4+ T cells and B cells is critical for the development of this disease. Remarkably elevated mRNA expression for IFN-gamma and IL-10 was observed in spleen cells of C57BL/6 mice starting from the early phase of viral infection. IFN-gamma production was induced by spleen cells from virus-infected mice upon stimulation with concanavalin A or lipopolysaccharide in both the early and late phases of MAIDS progression. When mice that had been passively administered anti-IFN-gamma mAb were infected with the virus, the development and progression of lymphadenopathy, immunodeficiency and elevated levels of serum IgG2a associated with MAIDS were delayed. Treatment with anti-IL-4 or anti-IL-10 mAb in place of anti-IFN-gamma mAb did not induce the delayed progression of MAIDS. These data support the concept that IFN-gamma-dependent pathway may be involved in the development of MAIDS.

The design, expression, and characterization of human insulin-like growth factor II (IGF-II) mutants specific for either the IGF-II/cation-independent mannose 6-phosphate receptor or IGF-I receptor

Five mutants of recombinant insulin-like growth factor-II (rIGF-II) that bound with high affinity to either the IGF-II/cation-independent mannose 6-phosphate (IGF-II/CIM6-P) or the IGF-I receptor were prepared by site-directed mutagenic procedures, expressed as fusion proteins in the larva of Bombyx mori or Escherichia coli, purified to homogeneity, renatured, and characterized in terms of their receptor binding affinities and specificities as well as their biological activities. Class I mutants in which Phe26, Tyr27, and Val43 were substituted with Ser, Leu, and Leu, respectively, bound to enriched preparations of rat placental IGF-II/CIM6-P receptors with apparent equilibrium dissociation constants (Kd(app)) that were only slightly greater, i.e. 0.10, 0.05, and 0.06 nM, than that of rIGF-II (0.04 nM) or hIGF-II (0.03 nM). In contrast, replacing Phe26 with Ser resulted in 5- and 20-fold decreases in the affinities of this mutant for highly purified human placental IGF-I and insulin receptors, respectively. The affinities of the two other Class I mutants, [Leu27]- and [Leu43]rIGF-IIs, for these two receptors were reduced 80- to 220-fold. The affinities of Class II mutants, i.e. [Thr48,Ser49,Ile50]- and [Arg54,Arg55] rIGF-IIs, for IGF-I receptors were as potent as rIGF-II; however, they bound very poorly or not at all to the IGF-II/CIM6-P receptor. In the binding study of those mutant rIGF-IIs, IGF-II was observed to have an unexpectedly high affinity for pure human placental insulin receptor preparations. For example, the affinities of hIGF-II, rIGF-II, and two Class II rIGF-II mutants for the insulin receptor were only 3-, 9-, and 5-fold less, respectively, than that of porcine insulin. In two biological assay systems, i.e. the stimulation of DNA synthesis in Balb/c 3T3 cells and glycogen synthesis in HepG2 cells, the Kd(app) of the rIGF-II mutants for the IGF-I receptor but not the IGF-II/CIM6-P receptor correlated with their abilities to produce biological responses.

Adjuvant activity of chitin derivatives in mice and guinea-pigs

Adjuvant activity of chitin derivatives was examined in guinea-pigs and mice. Among derivatives of chitin tested, 30 and 70% deacetylated chitin (DAC-30 and DAC-70), were active as adjuvants for the circulating-antibody formation to bacterial alpha-amylase and for the induction of delayed-type hypersensitivity to azobenzenearsonate-N-acetyl-L-tyrosine. DAC-70 enhanced the helper T cell function, the generation of alloreactive cytotoxic T lymphocytes, and the activity of natural killer cells in mice, however, it was inactive as mitogen. Other derivatives of chitin showed weaker or no adjuvant activity compared with DAC-70. Carboxymethyl-, hydroxyethyl and dihydroxypropyl-chitin showed weak mitogenic activities on normal spleen cells.