Immunomodulating functions of recombinant ovine interferon tau: potential for therapy in multiple sclerosis and autoimmune disorders

Expression, Purification, and Bioactivity of a Soluble Recombinant Ovine Interferon-tau in Escherichia Coli

INTRODUCTION

Ovine interferon-tau (oIFN-τ) is a newly discovered type I interferon. This study used biochemical techniques to transform the oIFN-τ gene into Escherichia coli to obtain the mass and soluble expression of the recombinant protein.

MATERIAL AND METHODS

First, total RNA was extracted from fresh sheep embryonic tissues with TRIzol reagent and then used as a template to reverse transcribe and amplify the mature oIFN-τ gene with RT-PCR. The amplified product was next digested with the HindIII and XhoI restriction enzymes and inserted into the pET-32a(+) vector to construct the prokaryotic expression plasmid. The corrected in-frame recombinant plasmid, pET-32a(+)-oIFN-τ, was transformed into E. coli Rosetta (DE3) competent cells. After induction with isopropyl-beta-D-thiogalactopyranoside (IPTG), the recombinant protein was detected in bacteria. Finally, the bacteria were lysed by sonication, and the recombinant protein was purified by nickel affinity chromatography and DEAE anion exchange chromatography.

RESULTS

The protein was confirmed to be oIFN-τ, which mainly existed in the soluble lysate fraction, as proven by SDS-PAGE and Western blot assays.

CONCLUSION

Purified IFN-τ exists mostly in a soluble form, and its anti-vesicular stomatitis virus (VSV) activity reached 7.08×10(6)IU/mL.

Bovine Interferon-Tau Activates Type I interferon-Associated Janus-signal Transducer in HPV16-positive Tumor Cell

The mechanisms of signal transduction by interferon-tau (IFN-τ) are widely known during the gestation of ruminants. In trophoblast cells, IFN-τ involves the activation of the JAK-STAT pathway, and it can have effects on other cell types, such as tumor cells. Here we report that the HPV16-positive BMK-16/myc cell treated with ovine IFN-τ, results in the activation of the canonical JAK-STAT and non-canonical JAK-STAT pathway. The MAPK signaling pathway was activated, we detected the proteins MEK1, MEK2, Raf1, STAT3, STA4, STAT5 and STAT6. Moreover, IFN-τ induced the expression of MHC Class I, MX and IP10 in the tumor cells and this response may be associated with the viral replication and with the anti-proliferative and the immunoregulatory effects of IFN-τ.

Superantigens: The Good, the Bad, and the Ugly

Increasing evidence suggests that superantigens play a role in Immune-mediated diseases. Superantigens are potent activators of CD4* T cells, causing rapid and massive proliferation of cells and cytokine production. This characteristic of superantigens can be exploited in diseases where strong immunologic responses are required, such as in the B16F10 animal model of melanoma. Superantigen administration is able to significantly enhance Ineffective anti-tumor Immune responses, resulting in potent and long-lived protective anti-tumor immunity. However, superantigens are more well-known for the role they play in diseases. Studies using an animal model for neurologic demy-elinatlng diseases such as multiple sclerosis show that superantigens can induce severe relapses and activate auto-reactive T cells not involved in the Initial bout of disease. This may also involve epitope spreading of disease. Superantigens have also been implicated in acute diseases such as food poisoning and TSS, and in chronic diseases such as psoriasis and rheumatoid arthritis. Viral superantigens are also involved in the disease process, including superantigens derived from human Immunodeficiency virus and mouse mammary tumor virus. Finally, immunotherapies that ameliorate the role played by superantigens in disease are discussed.

Pregnancy and interferon tau regulate N-myc interactor in the ovine uterus

In ruminants, interferon tau (IFNT) is synthesized and secreted by the mononuclear trophectoderm cells of the conceptus and maintains the corpus luteum and its secretion of progesterone for successful implantation and maintenance of pregnancy. In this study, we examined regulation of the expression of N-myc interactor (NMI) gene by IFNT in the ovine uterus based on results of microarray data from a study that compared gene expression by human 2fTGH and U3A (STAT1-null 2fTGH) cell lines in response to treatment with IFNT or vehicle. In the present study, semiquantitative reverse transcription-polymerase chain reaction analyses verified that IFNT stimulated expression of NMI mRNA in 2fTGH (ie, in a STAT1-dependent manner), but not in U3A (STAT1-null) cells. Furthermore, results of western blot analyses indicated that immunoreactive NMI proteins in 2fTGH and U3A cell lines increased in a time-dependent manner only in response to IFNT. In ovine endometria, steady-state levels of NMI mRNA increased between days 14 and 16 of pregnancy and then decreased slightly by day 20, but there was no effect of day of the estrous cycle. Expression of NMI mRNA was most abundant in endometrial stromal cells, glandular epithelium, and conceptus trophectoderm. Intrauterine infusion of IFNT in cyclic ewes increased expression of NMI in the endometrium. Expression of NMI in ovine and bovine uterine cell lines increased in response to IFNT. Collectively, the results of the present study indicate that IFNT regulates expression of NMI mRNA and protein in ovine endometria during pregnancy via a STAT1-dependent cell signaling pathway.

Biological effects of Byrsocarpus coccineus in vitro

CONTEXT

Byrsocarpus coccineus Schum. and Thonn. (Connaraceae) is a scandent shrub widely employed as a medicinal remedy for various disease conditions in West Africa.

OBJECTIVE

This study evaluated fractions of B. coccineus for modulation of cytochrome P450 (CYP) enzyme activity, cytokine production, and proliferation.

MATERIALS AND METHODS

The BROD (benzyloxyresorufin O-debenzylase) and BFCOD (benzyloxy-4-[trifluoromethyl]-coumarin O-debenzyloxylase) assays were used to evaluate effect on CYP2B1/2 and CYP3A4 enzyme activity. Effects on cytokine production and proliferation of HT29 cells were investigated using interferon expression assay and MTT (3-3[4,5-dimethyl-2-thiazolyl]-2-5-diphenyl-2H-tetrazolium bromide) assay, respectively.

RESULTS

Fractions derived from the organic solvent extraction of B. coccineus produced significant (p<0.05) stimulation of human hepatic CYP2B1/2 activity in the BROD assay. The greatest effects were elicited at 1 ng/mL corresponding to ∼ 3-fold stimulation of enzyme activity. Enhancement of CYP3A4 enzyme activity was also observed in the BFCOD assay. Other fractions from the organic extract showed significant antiproliferative effects on HT29 cells at 100 μg/mL. Fractions obtained from the aqueous extract of B. coccineus (1 µg/µL) significantly stimulated the expression of IFNα2a and IFNβ in peripheral blood mononuclear cells (PBMC), causing a maximum 26-fold increase of IFNα2a-transcript.

DISCUSSION AND CONCLUSION

The effect on CYP suggests that B. coccineus may reduce the therapeutic efficacy of co-administered drugs. This justifies the need for proper education of patients by healthcare practitioners on the outcomes of drug-herb interactions. This study identifies several in vitro activities that could underlie the attributed uses of this plant in traditional African medicine (TAM).

Pregnancy and interferon tau regulate DDX58 and PLSCR1 in the ovine uterus during the peri-implantation period

Interferon τ (IFNT), the pregnancy recognition signal in ruminants, abrogates the luteolytic mechanism for maintenance of the corpus luteum for production of progesterone (P(4)). This study examined the expression of DEAD (Asp-Glu-Ala-Asp) box polypeptide 58 (DDX58) and phospholipid scramblase 1 (PLSCR1) mRNAs in the ovine uterus as these genes were increased most in 2fTGH (STAT1 positive) cells by IFNT. The results of this study indicated that IFNT regulates expression of DDX58 and PLSCR1 mRNAs in the ovine uterus, which confirmed the results of the in vitro transcriptional profiling experiment with the 2fTGH (parental STAT1 positive) and U3A (STAT1 null) cell lines. Steady-state levels of DDX58 and PLSCR1 mRNAs increased in cells of the ovine uterus between days 12 and 20 of pregnancy, but not between days 10 and 16 of the estrous cycle. The expression of DDX58 and PLSCR1 mRNAs was greatest in endometrial stromal cells, but there was transient expression in uterine luminal and superficial glandular epithelial cells. P(4) alone did not induce expression of DDX58 and PLSCR1 mRNAs; however, intrauterine injections of IFNT did induce expression of DDX58 and PLSCR1 mRNAs in the endometria of nonpregnant ewes independent of effects of P(4). These results indicate that IFNT induces expression of DDX58 and PLSCR1 in ovine endometrial cells via the classical STAT1-mediated cell signaling pathway. Based on their known biological effects, DDX58 and PLSCR1 are IFN-stimulated genes, which may increase the antiviral status of cells of the pregnant uterus to protect against viral infection and/or enhance secretion of type I IFNs that inhibit viral replication.

Pregnancy and interferon tau regulate RSAD2 and IFIH1 expression in the ovine uterus

Radical S-adenosyl methionine domain containing 2 (RSAD2) encodes a cytoplasmic antiviral protein induced by interferons (IFN). Interferon-induced with helicase C domain 1 (IFIH1) is a RNA helicase involved in innate immune defense against viruses, growth suppression, and apoptosis. Interferon tau (IFNT), a Type I IFN produced by the peri-implantation ruminant conceptus, acts on the uterine endometrium to signal pregnancy recognition and promote receptivity to implantation. Transcriptional profiling identified RSAD2 and IFIH1 as IFNT regulated genes in the ovine uterine endometrium. This study tested the hypothesis that RSAD2 and IFIH1 were induced in the endometrium in a cell type-specific manner by IFNT from the conceptus during early pregnancy. Endometrial RSAD2 and IFIH1 mRNA increased between days 12 and 16 of pregnancy, but not of the estrous cycle. In pregnant ewes, RSAD2 and IFIH1 mRNAs increased in endometrial glands, and stroma and immune cells, but not in the luminal epithelium. Neither gene was expressed in the trophectoderm of day 18 or 20 conceptuses. Progesterone (P4) treatment of ovariectomized ewes did not induce expression RSAD2 or IFIH1 mRNA in the endometrium; however, intrauterine injections of IFNT induced expression of RSAD2 and IFIH1 mRNA in endometria of ewes treated with P4, as well as in ewes treated with P4 and the progesterone receptor antagonist, ZK 136,317. These results indicate that conceptus IFNT induces both RSAD2 and IFIH1 in a P4-independent manner in the ovine uterine endometrium. These two IFNT-stimulated genes are proposed to have biological roles in the establishment of uterine receptivity to the conceptus during implantation through induction of an antiviral state and modulation of local immune cells in the endometrium.

Preliminary studies of cytokine secretion patterns associated with pregnancy in MS patients

Multiple sclerosis has a tendency to remit during pregnancy, followed by an increase in the risk for disease relapses in the postpartum period. In this communication, preliminary data are presented to indicate that activated peripheral blood mononuclear cells (PBMC) from the postpartum period secrete elevated levels of gamma-interferon (IFN-gamma) relative to those collected during the third trimester. In addition, myelin antigen-specific T cell lines established from the third trimester of pregnancy secrete elevated levels of interleukin-10. The data suggest that the study of the mechanisms underlying natural fluctuations in disease activity during pregnancy and the postpartum period holds promise for a better understanding of factors capable of initiating and regulating remission and exacerbation in MS.

Optimization of cell density and dilution rate in Pichia pastoris continuous fermentations for production of recombinant proteins

This paper provides an approach for optimizing the cell density (Xc) and dilution rate (D) in a chemostat for a Pichia pastoris continuous fermentation for the extracellular production of a recombinant protein, interferon tau (INF-tau). The objective was to maximize the volumetric productivity (Q, mg INF-tau l(-1) h(-1)), which was accomplished using response surface methodology (RSM) to model the response of Q as a function of Xc and D within the ranges 150< or = Xc < or =450 g cells (wet weight) l(-1) and 0.1 microm< or = D< or =0.9 microm (microm=0.0678 h(-1), the maximum specific growth rate obtained from a fed-batch phase controlled with a methanol sensor). The methanol and medium feed rates that resulted in the desired Xc and D were determined based on the mass balance. From the RSM model, the optimal Xc and D were 328.9 g l(-1) and 0.0333 h(-1) for a maximum Q of 2.73 mg l(-1) h(-1). The model of specific production rate (rho, mg INF-tau g(-1) cells h(-1)) was also established and showed the optimal Xc 287.7 g l(-1) and D=0.0361 h(-1) for the maximum rho (predicted to be 8.92 x 10(-3) mg(-1) g(-1) h(-1)). The methanol specific consumption rate (nu, g methanol g(-1) cells h(-1)) was calculated and shown to be independent of the cell density. The relationship between nu and mu (specific growth rate) was the same as that discovered from fed-batch fermentations of the same strain. The approach developed in this study is expected to be applicable to the optimization of continuous fermentations by other microorganisms.

Interferon-tau (IFNtau) regulation of IFN-stimulated gene expression in cell lines lacking specific IFN-signaling components

Interferon-tau (IFNtau) is a unique type I IFN secreted by the ruminant conceptus that acts in a paracrine manner on the endometrial epithelium to signal pregnancy recognition. In the ovine endometrium, IFNtau suppresses estrogen receptor alpha and oxytocin receptor gene expression, but increases or induces expression of IFN-simulated genes (ISGs), including signal transducer and activator of transcription-1 (STAT1), STAT2, ISG factor-3gamma (ISGF3gamma)/p48/IFN regulatory factor-9, and 2',5'-oligoadenylate synthetase (OAS). Human fibroblast cell lines lacking specific IFN signaling components were employed to determine the roles of STAT1, STAT2, and ISGF3gamma in the effects of IFNtau on ISG protein expression. Results indicated that STAT1alpha or STAT1beta is required for IFNtau effects on STAT2, ISGF3gamma, and OAS (40/46, 69/71, and 100 kDa). STAT2 is required for effects on STAT1, ISGF3gamma, and all OAS forms. ISGF3gamma is required for effects of IFNtau on STAT2 and 40/46- and 69/71-kDa OAS and plays a role in the effects of IFNtau on 100-kDa OAS and STAT1. Mutation of Tyr(701), but not Ser(727), of STAT1 abolished the effects of IFNtau on ISG expression. Mutation of the SH2 domain of STAT1 abolished the effects of IFNtau on all ISGs and reduced increases in 100-kDa OAS. These data illustrate the importance of transcription factors composed of STAT1, STAT2, and ISGF3gamma in the signaling pathway mediating the effects of IFNtau on ISG expression.