Ovine IFN-tau modulates the expression of MHC antigens on murine cerebrovascular endothelial cells and inhibits replication of Theiler's virus

Specific microRNA library of IFN-τ on bovine endometrial epithelial cells

IFN-τ is specifically secreted by the conceptus in ruminants during early pregnancy, and it plays a vital role in the immunological function of pregnancy. However, its mechanism involving microRNA (miRNA) is still not well understood. Deep sequencing was used to explore the specific miRNA library of IFN-τ on bovine endometrial epithelial cells (bEECs). The results showed that 574 known bovine miRNAs and 109 novel miRNAs were identified. We found 74 differentially expressed miRNAs, including 30 commonly expressed miRNAs in the experiment. Then, qPCR verification of six selected miRNAs showed that they corresponded with the sequencing data. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed significant enrichment of predicted target genes of differentially expressed miRNAs, including influenza A, herpes simplex infection, antigen processing and presentation, viral myocarditis, TNF signaling pathway, graft-versus-host disease, and allograft rejection. These results may provide important contributions to the immune response during early pregnancy in ruminants, but further studies are need to verify the proposed cellular/immunological effects and role of specific miRNA as biomarkers in vivo.

IFN-τ Displays Anti-Inflammatory Effects on Staphylococcus aureus Endometritis via Inhibiting the Activation of the NF-κB and MAPK Pathways in Mice

The aim of the present study was to determine the anti-inflammatory effect of IFN-τ on endometritis using a mouse model of S. aureus-induced endometritis and to elucidate the mechanism of action underlying these effects. In the present study, the effect of IFN-τ on S. aureus growth was monitored by turbidimeter at 600 nm. IFN-τ did not affect S. aureus growth. The histopathological changes indicated that IFN-τ had a protective effect on uterus tissues with S. aureus infection. The ELISA and qPCR results showed the production of the proinflammatory cytokines TNF-α, IL-1β, and IL-6 was decreased with IFN-τ treatment. In contrast, the level of the anti-inflammatory cytokine IL-10 was increased. We further studied the signaling pathway associated with these observations, and the qPCR results showed that the expression of TLR2 was repressed by IFN-τ. Furthermore, the western blotting results showed the phosphorylation of IκB, NF-κB p65, and MAPKs (p38, JNK, and ERK) was inhibited by IFN-τ treatment. The results suggested that IFN-τ may be a potential drug for the treatment of uterine infection due to S. aureus or other infectious inflammatory diseases.

Interferon-tau: current applications and potential in antiviral therapy

Interferon-tau (IFN-tau) was initially identified as an ovine pregnancy protein. Produced by the trophoblast, it is important in preventing degradation of the corpus luteum and has been used as an early marker for ovine pregnancy. As a member of the family of type I interferons, IFN-tau has demonstrated promising antiviral activity against human viral infections in vitro. Additionally, it displays high species cross-reactivity despite its absence in humans. To date, IFN-tau has shown efficacy in reducing replication of human immunodeficiency virus, feline immunodeficiency virus, and human papillomavirus. While IFN-tau shares similar antiviral activity to IFN-alpha, the current interferon of choice for treatment of viral infections, it lacks the associated toxicity. This may make IFN-tau an attractive alternative to IFN-alpha for the treatment of viral infections.

Interplay between ovine bone marrow stromal cell antigen 2/tetherin and endogenous retroviruses

Endogenous betaretroviruses (enJSRVs) of sheep are expressed abundantly in the female reproductive tract and play a crucial role in conceptus development and placental morphogenesis. Interestingly, the colonization of the sheep genome by enJSRVs is likely still ongoing. During early pregnancy, enJSRV expression correlates with the production of tau interferon (IFNT), a type I IFN, by the developing conceptus. IFNT is the pregnancy recognition signal in ruminants and possesses potent antiviral activity. In this study, we show that IFNT induces the expression of bone marrow stromal cell antigen 2 (BST2) (also termed CD317/tetherin) both in vitro and in vivo. The BST2 gene is duplicated in ruminants. Transfection assays found that ovine BST2 proteins (oBST2A and oBST2B) block release of viral particles produced by intact enJSRV loci and of related exogenous and pathogenic jaagsiekte sheep retrovirus (JSRV). Ovine BST2A appears to restrict enJSRVs more efficiently than oBST2B. In vivo, the expression of BST2A/B and enJSRVs in the endometrium increases after day 12 and remains high between days 14 and 20 of pregnancy. In situ hybridization analyses found that oBST2A is expressed mainly in the endometrial stromal cells but not in the luminal and glandular epithelial cells, in which enJSRVs are highly expressed. In conclusion, enJSRVs may have coevolved in the presence of oBST2A/B by being expressed in different cellular compartments of the same organ. Viral expression in cells unable to express BST2 may be one of the mechanisms used by retroviruses to escape restriction.

Down-regulation of Jab1, HIF-1alpha, and VEGF by Moloney murine leukemia virus-ts1 infection: a possible cause of neurodegeneration

Moloney murine leukemia virus-temperature sensitive (MoMuLV-ts1)-mediated neuronal death is a result of both loss of glial support and release of cytokines and neurotoxins from ts1-infected glial cells. Here the authors propose vascular endothelial growth factor (VEGF) down-regulation as another contributory factor in neuronal degeneration induced by ts1 infection. To determine how ts1 affects VEGF expression in ts1-infected brain, the authors examined the expression of several proteins that are important in regulating the expression of VEGF. The authors found significant decreases in Jun-activating domain-binding protein 1 (Jab1), hypoxia-inducible factor (HIF)-1alpha, and VEGF levels and increases in p53 protein levels in ts1-infected brains compared to noninfected control brains. The authors suggest that a decrease Jab1 expression in ts1 infection leads to accumulation of p53, which binds to HIF-1alpha to accelerate its degradation. A rapid degradation of HIF-1alpha leads to decreased VEGF production and secretion. Considering that endothelial cells are the most conspicuous in virus replication and production in ts1 infection, but are not killed by the infection, the authors examined the expression of these proteins using infected and noninfected mouse cerebrovascular endothelial (CVE) cells. The ts1- infected CVE cells showed decreased Jab1, HIF-1alpha, and VEGF mRNA and protein levels and increased p53 protein levels compared with noninfected cells, consistent with the results found in vivo. These results confirm that ts1 infection results in insufficient secretion of VEGF from endothelial cells and may result in decreased neuroprotection. This study suggested that ts1-mediated neuropathology in mice may result from changes in expression and activity of Jab1, p53, and HIF-1alpha, with a final target on VEGF expression and neuronal degeneration.

Pregnancy and interferon tau regulate major histocompatibility complex class I and beta2-microglobulin expression in the ovine uterus

Major histocompatibility complex (MHC) class I molecules, consisting of an alpha chain and beta2-microglobulin (beta2MG), play an important role in immune rejection responses by discriminating self and nonself and are increased by type I interferons during antiviral responses. Interferon tau (IFNtau), the pregnancy-recognition signal in ruminants, is a type I interferon produced by the ovine conceptus between Days 11 and 21 of gestation. In study 1, expression of MHC class I alpha chain and beta2MG mRNA and protein was detected primarily in endometrial luminal epithelium (LE) and glandular epithelium (GE) on Days 10 and 12 of the estrous cycle and pregnancy. On Days 14-20 of pregnancy, MHC class I and beta2MG expression increased only in endometrial stroma and GE and, concurrently, was absent in LE and superficial ductal GE (sGE). Although neither MHC class I nor beta2MG proteins were detected in Day 20 trophectoderm, beta2MG mRNA was detected in conceptus trophectoderm. In study 2, cyclic ewes were ovariectomized on Day 5, treated daily with progesterone to Day 16, received intrauterine infusions between Days 11 and 16 of either control serum proteins or recombinant ovine IFNtau, and were hysterectomized on Day 17. The IFNtau increased MHC class I and beta2MG expression only in endometrial stroma and GE. During pregnancy, MHC class I and beta2MG gene expression is inhibited in endometrial LE and sGE but, paradoxically, is stimulated by IFNtau in the stroma and GE. The silencing of MHC class I alpha chain and beta2MG genes in the endometrial LE and sGE during pregnancy recognition and establishment may be a critical mechanism preventing immune rejection of the conceptus allograft.