Isolation, antiproliferation on tumor cell and immunomodulatory activity of BSP-I, a novel bursal peptide from chicken humoral immune system

The Inducing Roles of the New Isolated Bursal Hexapeptide and Pentapeptide on the Immune Response of AIV Vaccine in Mice

BACKGROUND

Bursa of Fabricius is the acknowledged central humoral immune organ. The bursal-derived peptides play the important roles on the immature B cell development and antibody production.

OBJECTIVES

Here we explored the functions of the new isolated bursal hexapeptide and pentapeptide on the humoral, cellular immune response and antigen presentation to Avian Influenza Virus (AIV) vaccine in mice immunization.

METHODS

The bursa extract samples were purified following RP HPLC method, and were analyzed with MS/MS to identify the amino acid sequences. Mice were twice subcutaneously injected with AIV inactivated vaccine plus with two new isolated bursal peptides at three dosages, respectively. On two weeks after the second immunization, sera samples were collected from the immunized mice to measure AIV-specific IgG antibody levels and HI antibody titers. Also, on 7th day after the second immunization, lymphocytes were isolated from the immunized mice to detect T cell subtype and lymphocyte viabilities, and the expressions of co-stimulatory molecule on dendritic cells in the immunized mice.

RESULTS

Two new bursal hexapeptide and pentapeptide with amino acid sequences KGNRVY and MPPTH were isolated, respectively. Our investigation proved the strong regulatory roles of bursal hexapeptide on AIV-specific IgG levels and HI antibody titers, and lymphocyte viabilities, and the significant increased T cells subpopulation and expressions of MHCII molecule on dendritic cells in the immunized mice. Moreover, our findings verified the significantly enhanced AIV-specific IgG antibody and HI titers, and the strong increased T cell subpopulation and expressions of CD40 molecule on dendritic cells in the mice immunized with AIV vaccine and bursal pentapeptide.

CONCLUSION

We isolated and identified two new hexapeptide and pentapeptide from bursa, and proved that these two bursal peptides effectively induced the AIV-specific antibody, T cell and antigen presentation immune responses, which provided an experimental basis for the further clinical application of the bursal derived active peptide on the vaccine improvement.

Comparison of immunoadjuvant activities of four bursal peptides combined with H9N2 avian influenza virus vaccine

The bursa of Fabricius (BF) is a central humoral immune organ unique to birds. Four bursal peptides (BP-I, BP-II, BP-III, and BP-IV) have been isolated and identified from the BF. In this study, the immunoadjuvant activities of BPs I to IV were examined in mice immunized with H9N2 avian influenza virus (AIV) vaccine. The results suggested that BP-I effectively enhanced cell-mediated immune responses, increased the secretion of Th1 (interferon gamma)- and Th2 (interleukin-4)-type cytokines, and induced an improved cytotoxic T-lymphocyte (CTL) response to the H9N2 virus. BP-II mainly elevated specific antibody production, especially neutralizing antibodies, and increased Th1- and Th2-type cytokine secretion. BP-III had no significant effect on antibody production or cell-mediated immune responses compared to those in the control group. A strong immune response at both the humoral and cellular levels was induced by BP-IV. Furthermore, a virus challenge experiment followed by H&E staining revealed that BP-I and BP-II promoted removal of the virus and conferred protection in mouse lungs. BP-IV significantly reduced viral titers and histopathological changes and contributed to protection against H9N2 AIV challenge in mouse lungs. This study further elucidated the immunoadjuvant activities of BPs I to IV, providing a novel insight into immunoadjuvants for use in vaccine design.

The immunomodulatory peptide bursopentin (BP5) enhances proliferation and induces sIgM expression in DT40 cells

BACKGROUND

In the recent past, many studies have been focused on extracts of BF and multiple biologically active factors and their effects on humoral immune system in chickens and birds. However, the mechanism of those immunomodulatory peptides on the B lineage cells proliferation and antibody production in chicken is fairly unknown. DT40 cell line, an avian leucosis virus-induced chicken pre-B cell line, expresses immunoglobulin M (IgM) isotype B cell reporter in the plasma membrane. There are many evidences suggesting that DT40 cells are best characterized as a bursal stem cell line. Because of the unique characteristics of DT40 cell line, it has been widely used to observe biological processes of pre-B lymphocyte cell within living cells.

METHODS

The chicken B cell line DT40 was cultured in Roswell Park Memorial Institute (RPMI) 1640 medium and cytotoxicity was studied. Also, effect of BP5 on cell proliferation and cell cycle distribution of DT40 cells was studied. Also, the effect of BP5 on sIgM mRNA expression was studied by using real-time PCR.

OBJECTIVES

To investigat the effects of Bursopentin (Cys-Lys-Arg-Val-Tyr, BP5) on a chicken promyelocyte cell line DT40, assays of cell proliferation, cell cycle distribution, detection of surface immunoglobulin G (sIgM) mRNA expression and gene microarray analysis were performed.

RESULTS

The results showed that BP5 displayed concentration-dependent effects on the proliferation, cell cycle, and sIgM mRNA expression in DT40 cells. And the analysis of expression profiles identified a signature set of 3022 genes (1254 up regulated genes, 1762 down regulated genes), which clearly discriminated the BP5-treated DT40 cells from control with high certainty (P≤0.02). The results of microarray analysis were confirmed by quantitative reverse transcription-polymerase chain reaction for 12 of the differentially expressed genes.

CONCLUSION

Theses findings showed the immuno-activity effect of BP5 on B lymphocyte and indicated that BP5 treatment regulated eight signaling pathways, in which Toll-like signaling pathway was the most significant enrichment pathway.

The potential molecular effects of bursal septpeptide II on immune induction and antitumor activity

The bursa of Fabricius (BF) is the acknowledged central humoral immune organ in birds. Bursal septpeptide II (BSP-II) is an immunomodulatory bioactive peptide isolated from BF. To understand the effects of BSP-II on immune induction, gene expression profiles of hybridoma cells treated with BSP-II were evaluated. Pathway analysis showed that regulated genes were involved in cytokine-cytokine receptor interactions, T cell receptor signaling pathway, and pathway in cancer. It was observed that BSP-II reduced tumor cells proliferation and stimulated p53 expression. These results indicate potential mechanisms underlying the effects of the humoral immune system on immune induction, including antitumor activities. Our study has provided a novel insight into immunotherapeutic strategies for treating human tumors.

BP8, a novel peptide from avian immune system, modulates B cell developments

The bursa of Fabricius (BF) is the key humoral immune organ unique to birds, and is critical for early B-lymphocyte proliferation and differentiation. However, the molecular basis and mechanisms through which the BF regulates B cell development are not fully understood. In this study, we isolated and identified a new bursal peptide (BP8, AGHTKKAP) by RP-HPLC and MALDI-TOF-MS. BP8 promoted colony-forming pre-B formation, bound B cell precursor, regulated B cell development in vitro as well as in vivo, upstream of the EBF-E2A-Pax5 regulatory complex and increased immunoglobulin secretion. These data revealed a bursal-derived multifunctional factor BP8 as a novel biomaterial which is essential for the development of the immune system. This study elucidates further the mechanisms involved in humoral immune system and has implications in treating human diseases.

Effect of sonication on B cell development and immunomodulatory functions of Bursa of Fabricius

A study was initiated with the objective of evaluating the effects of sonication treatment on important quality parameters of extract of Bursa of Fabricius. Sonication of extract was done (frequency 20 kHz and various amplitude levels) at 0 °C for 10 min, 30 min, 50 min, respectively. As results, the yield of bursa peptides significantly increased (p<0.05). Then we found sonicated bursa extract promoted the content of bursin and the CFU pre-B formation, exerted immunomodulatory function on antigen-specific immune responses in C57/BL6 mice immunized with inactivated Japanese encephalitis b virus (JEV) vaccine, including enhancing JEV-specific antibody and cytokine production, T-cell immunophenotyping and lymphocyte proliferation. Findings of the present study suggested the sonication treatment of Bursa of Fabricius could improve the yield as well as the quality of bursa peptides, indicating that sonication is effective in processing of bursa extract and could be a potential process for future immuno-pharmacological use.

Comparison of immunomodulatory functions of three peptides from the chicken bursa of Fabricius

The bursa of Fabricius (BF) is the acknowledged central humoral immune organ unique to birds which plays important roles in B cell development and antibody production. Little information on immunomodulatory functions of BF is reported, except for several reported active bursal-derived peptides. Three peptides were identified and characterized from BF through RP-HPLC and MADIL-TOF methods. They are named as bursal peptide (BP)-I, BP-II, BP-III. These peptides promoted CFU pre-B formation and decreased PU.1 expression. The different immunomodulatory activities of these three bursal peptides on antibody and cytokine productions were verified by the immunization comparative experiment. The results showed the three bursal peptides enhanced AIV-specific antibody and cytokine production, T-cell immunophenotyping at reachable concentrations. These results indicate the important orientations for the comprehensive understanding of the humoral central immune system, and provide a novel insight on new experimental reagents for immuno-adjuvant or immunopharmacological.

The potential mechanism of Bursal-derived BPP-II on the antibody production and avian pre-B cell

The bursa of Fabricius is critical for the normal development of the B lymphocytes responsible for antibody production. However, the mechanism of the bursal-derived bioactive factor on B cell development is little reported. In this paper, chicks were immunized with BPP-II and AIV vaccine or AIV antigen, and antibody and IL-4 production were detected. The results showed that BPP-II played strongly inducing roles on the humoral immune responses. To investigate the gene expression at transcriptional level, avian pre-B lymphocyte DT40 cells were treated with BPP-II, and were analyzed with the gene microarray. The results proved that BPP-II treatment regulated 11 pathways, in which homologous recombination is a vital mechanism which is involved in antibody Ig gene conversion and diversification during B cell development. These results suggested Bursal-derived biological active factor BPP-II might be involved in the antibody production processes and B cell development, which is vital to the humoral central immune organ, the bursa of Fabricius.

Immunomodulatory roles and functional analysis of pre-B lymphocyte DT40 cells with the bursal-derived BSP-II treatment

The bursa of Fabricius, the acknowledged central humoral immune organ, is vital to B cell differentiation. However, the regulatory function of the bursal-derived peptide on avian B cell proliferation has not been reported. BSP-II is a recently reported bursal-derived bioactive peptide. In this paper, 75 days-old chicks were twice subcutaneously immunized with BSP-II and inactivated avian influenza virus (AIV, H(9)N(2) strain). It was proved that BSP-II induced a strongly AIV-specific HI antibody production in the immunized chicks. Also, BSP-II could enhance avian pre-B lymphocyte DT40 cell viability. To investigate the global patterns of gene expression in DT40 cells after BSP-II treatment, gene microarray was carried out. It was identified that the differentially expressed genes were involved in various pathways, of which six pathways were associated with signaling transductions, including ErbB signaling, MAPK signaling, Toll-like receptor signaling, Notch signaling, mTOR signaling, and Wnt signaling. Finally, RT-qPCR was used to confirm the microarray expression data. These results indicated the molecular basis of pre-B lymphocyte viability with BSP-II treatment, which provided a potential mechanism of the bursa of Fabricius on pre-B lymphocyte viability, differentiation, and development. These results are valid for the mechanism of the bursa of Fabricius on B lymphocytes development.

Isolation, modulatory functions on murine B cell development and antigen-specific immune responses of BP11, a novel peptide from the chicken bursa of Fabricius

The bursa of Fabricius (BF) is the central humoral immune organ unique to birds which plays important roles in B lymphocyte differentiation. Here, a new bursal peptide (BP11) with the amino acid sequence DVAGKLPDNRT was identified and characterized from BF. It was proved that BP11 promoted CFU pre-B formation, and regulated B cell differentiation, including increase the percentage of immature and mature B cells in BM cells co-cultured with IL-7. BP11 also exerted immunomodulatory function on antigen-specific immune responses in BALB/c mice immunized with inactivated influence virus (AIV, H9N2 subtype) vaccine, including enhancing AIV-specific antibody and cytokine production. Furthermore, it was noteworthy that BP11 stimulated antibody productions and potentiates the Th1 and Th2-type immune responses in dose-dependent manner in chicken. These results suggested that BP11 might be highly relevant for the development of avian immune system.

Characterization and immunomodulatory function comparison of various bursal-derived peptides isolated from the humoral central immune organ

The bursa of Fabricius (BF) is the acknowledged central immune organ, which is important to the B cell differentiation and antibody production. However, due to difficult purification, the immunomodulatory peptides from BF were little reported. In this study, the extract samples of BF were taken to a chromatographic analysis by RP-HPLC. Five novel low molecular weight peptides were isolated from BF, with amino acid sequences of YEYAY, RMYEE, GPPAT, AGCCNG, and RRL, and named as Bursal pentapeptide (BPP)-III, -IV, -V, and Bursal hexapeptide (BHP), and Bursal tripeptide (BTP), respectively. BSP-I, BSP-II, BPP-I and BPP-II are recently reported to be the bursal-derived bioactive peptides. In this paper, we analyzed the chemical formula and characteristics of these nine bursal-derived peptides. The immunization comparative experiment verified the different immunomodulatory activity of these nine bursal peptides on antibody and cytokine productions. Furthermore, the results showed that at reachable concentrations, BPP-II and BPP-I induced antibody productions, lymphocyte viabilities and cytokine responses in different dose-dependent manner in the immunized mice model, respectively. These results provided important orientations for the comprehensively understanding and study of the humoral central immune system of human, and provided a novel insight on the treatment of serious disease and immune improvement of human.

Identification and characterization of novel immunomodulatory bursal-derived pentapeptide-II (BPP-II)

The bursa of Fabricius, the acknowledged central humoral immune organ, plays a vital role in B lymphocyte differentiation. However, there are few reports of the molecular basis of the mechanism on immune induction and potential antitumor activity of bursal-derived peptides. In this paper, a novel bursal-derived pentapeptide-II (BPP-II, MTLTG) was isolated and exerted immunomodulatory functions on antibody responses in vitro. Gene microarray analyses demonstrated that BPP-II regulated expression of 2478 genes in a mouse-derived hybridoma cell line. Immune-related gene ontology functional procedures were employed for further functional analysis. Furthermore, the majority of BPP-II-regulated pathways were associated with immune responses and tumor processes. Moreover, BPP-II exhibited immunomodulatory effects on antigen-specific immune responses in vivo, including enhancement of avian influenza virus (H9N2 subtype)-specific antibody and cytokine production and modification of T cell immunophenotypes and lymphocyte proliferation. Finally, BPP-II triggered p53 expression and stabilization and selectively inhibited tumor cell proliferation. These data identified the multifunctional factor, BPP-II, as a novel biomaterial representing an important linking between the humoral central immune system and immune induction, including antitumor. Information generated in this study elucidates further the mechanisms involved in humoral immune system and represents the potential basis of effective immunotherapeutic strategies for treating human tumors and immune improvement.