Constitutive or excessive activation of Toll-like receptor (TLR) signaling pathway can disrupt the body's immune tolerance to autoantigen, thus promoting the development of autoimmune disease. However, the expression profile of TLR signaling pathway in peripheral blood neutrophils in the pathogenesis of microscopic polyangiitis (MPA) remains unclear. Thus, improved understanding of the pathobiology of this disease may aid in the development of therapeutic targets for patients with MPA. In the present study, we assessed the expression of TLR signaling pathway-related genes in peripheral blood neutrophils in patients with MPA. PCR array analysis was performed on 20 patients with MPA and 12 healthy controls. Gene expression profile was performed using the human TLR for autoimmunity and inflammation PCR array of Genecopoeia, containing 84 genes related to TLR signaling pathway and six house-keeping genes. We then used quantitative real-time PCR to validate the array test. The array results identified 13 upregulated genes and 5 genes which were downregulated. The resulting qRT-PCR was consistent with the findings by PCR array. Our results suggest that peripheral blood neutrophils display changes in the expression of TLR signaling pathway-related genes associated with the pathogenesis of microscopic polyangiitis.

The 14-amino acid (IEGPTLRQWLAARA) thrombopoietin mimetic peptide (TMP) shares no sequence homology with native thrombopoietin (TPO). When dimerized, it displays a high-binding affinity for the TPO receptor and has equipotent bioactivity with recombinant human TPO (rhTPO) in stimulating proliferation and maturation of megakaryocytes in vitro. However, TMP is limited for clinical usage because of its short half-life in vivo. In this study, fusion proteins that composed of tandem dimer of TMP (dTMP) genetically fused at the C- or N-terminus of human serum albumin (HSA) were separately expressed in Chinese hamster ovary (CHO) cells. In vitro bioactivity assays showed that purified fusion proteins promoted the proliferation of megakaryocytes in a dose-dependent manner and activated signal transducer and activator of transcription (STAT) pathway in TPO receptor-dependent manner. Following subcutaneous administration, both HSA-dTMP and dTMP-HSA significantly elevated peripheral platelet counts in normal mice in a dose-dependent manner. In addition, fusion with HSA successfully prolonged dTMP half-life in mice. However, when HSA was fused at the C-terminus of dTMP, the bioactivity of dTMP-HSA was about half of that of HSA-dTMP. In conclusion, these results suggested that HSA/dTMP fusion proteins might be potential drugs for thrombocytopenia and, when HSA was fused at the N-terminus of dTMP, the fusion protein had a higher activity.

Background: Chinese hamster ovary (CHO) cells are the most dependable mammalian cells for the production of recombinant proteins. Replication-incompetent retroviral vector (retrovector) is an efficient tool to generate stable cell lines. Multiple copies of integrated genes by retrovector transduction results in improved recombinant protein yield. HEK-293 and their genetic derivatives are principal cells for retrovector production. Retrovectors packaged in HEK-293 cells pose a risk of infectious agent transmission, such as viruses and mycoplasmas, from serum and packaging cells. Results: In this report, retrovectors were packaged in CHO cells cultured in chemically defined (CD) media. The retrovectors were then used to transduce CHO cells. This method can block potential transmission of infectious agents from serum and packaging cells. With this method, we generated glucagon-like protein-1 Fc fusion protein (GLP-1-Fc) stable expression CHO cell lines. Productivity of GLP-1-Fc can reach 3.15 g/L. The GLP-1-Fc protein produced by this method has comparable bioactivity to that of dulaglutide (Trulicity). These stable cell lines retain 95-100% of productivity after 40 days of continuous culture (~48-56 generations). Conclusions: Suspension CHO cells are clean, safe, and reliable cells for retrovector packaging. Retrovectors packaged from this system could be used to generate CHO stable cell lines for recombinant protein expression. How to cite: Li J, Wei S, Cao C, et al. Retrovectors packaged in CHO cells to generate GLP-1-Fc stable expression CHO cell lines. Electron J Biotechnol 2019;41. https://doi.

Successful expression of HSA-TMP-TMP fusion protein in P. pastoris was achieved and the recombinant HSA-TMP-TMP is a promising TPO analog.