Date Published: July 6, 2017
Publisher: Public Library of Science
Author(s): Peiying Deng, Xue Li, Yi Wei, Juan Liu, Meng Chen, Yamei Xu, Bin Dong, Lingqun Zhu, Limin Chai, Jan P. A. Baak.
Angelicae Sinensis, Radix Astragali and Rhizoma Coptidis are all herbs of modified Danggui Buxue Tang (DGBX) and are extensively applied herbs in traditional Chinese medicine for the treatment of anemia and inflammation. In this study, immune-induced AA mice were used as an animal model, and the immunosuppressive agent, Ciclosporin A (CsA), was used as a positive control. Multiple pro-inflammatory cytokines were examined by bead-based multiplex flow cytometry. The T-cell subsets were assessed using a fluorescence-activated cell sorter (FACS). Western blot analysis was used to estimate the protein expression levels of specific transcription factors for T helper cells (Th1, Th2 and Th17) and key molecules of the Janus-activated kinase (Jak)/signal transducer and activator of transcription (Stat3) signaling pathway. DGBX treatment could significantly increase the production of whole blood cells in peripheral blood (PB); inhibit the expansion of Th1 and Th17 cells; increase the differentiation of Th2 and Tregs cells; regulate the expression levels of T-bet, GATA-3, RORγ and proinflammatory cytokines; and decrease the expression levels of key molecules in the Jak/Stat signaling pathway. These results indicate that DGBX can regulate the differentiation of T lymphocytes, resulting in immunosuppressive and hematogenic functions on AA mice. DGBX might be a good candidate for inclusion in a randomized study for AA with more data on the possible side effects and doses used in humans. Ultimately, it may be used for applications of traditional medicine against AA in modern complementary and alternative immunosuppressive therapeutics.
Aplastic anemia (AA) is a bone marrow failure syndrome characterized by the reduction or absence of mature hemopoietic progenitors in all cell lineages . Most cases of AA are associated with an aberrant immune response. Cytotoxic T cells (CD8+) are expanded in AA and are involved in the production of proinflammatory cytokines, including interferon (IFN) γ, tumor necrosis factor (TNF) αand interleukin (IL)-1β, which induce immune destruction and apoptosis of hematopoietic progenitor cells . Several studies have confirmed that T helper (Th) cells, including IFNγ-producing (Th1), IL-4-producing and IL-17-producing (Th17) CD4+ T cells, play pivotal roles in autoimmunity [3, 4] and contribute to the pathogenesis of AA. Regulatory T cells (Tregs), specifically expressing CD25 and transcription factor FOXP3, maintain the immunologic self-tolerance and immunosuppression [5, 6]. Intrinsic impairment of Tregs plays a critical role in the pathophysiology of AA . Treg-mediated immunosuppressive strategies should contribute to suppressing excessive Th1 and Th17 immune responses in AA.
AA is an immune-mediated bone marrow failure syndrome. The pathophysiology of AA occurs via immune destruction in HSCs attacked by CD8+ cytotoxic T cells (CTLs), CD4+ Th1 and Th17 cells [26, 27]. CTLs produce pro-inflammatory cytokines, including IFNγ and TNFα, to activate the Fas-dependent pathway to induce the apoptosis of CD34+ HSCs . A proper balance between Th1 and Th2 is important in maintaining the homeostasis of hemopoietic progenitor cells. Untreated AA patients have a higher proportion of Th1 cells, which produce IFNγ and IL-2, due to a shift in the IFNγ/IL-4 ratio induced by the immune response . Aberrant activated Th1 cells also secrete IFNγ and TNFα, contributing to the immune attack of HSCs and inhibiting hematopoietic colony formation . The impaired function of CD4+CD25+Foxp3+ Tregs has been confirmed to contribute to the pathogenesis of autoimmune diseases including AA . Tregs appear to have intrinsic impairment of functions of suppressing normal effector T cell effects and the production of IFNγ in patients with AA [31, 32]. The Treg-mediated immunosuppressive strategy is beneficial to suppress excessive Th immune response in AA . Th17 cells specifically secreting IL-17 were expanded in the acquired AA, which was correlated with the severity of this disease. The expansion of Th17 cells correlated with the depletion of Tregs and showed a reciprocal function between Th17 and Tregs, contributing to the autoimmune process of AA . The combination of Th1 and Th17 expansion and the decrease in the Th2 and Tregs immunophenotype and function contributed to the hematopoietic failure induced by the immune attack on the bone marrow .
Our sudy confirmed that DGBX treatment could decrease the proliferation and differentiation of effector T cells and impair Treg-mediated immunosuppressive functions. DGBX treatment inhibited the activiation of the Jak/Stat signaling pathway by regulating the expression of key molecules and contributed to the repair of aberrant immune responses and deficiencies in hematopoietic cells. These results suggest that DGBX might be tried in a randomized study for AA, although more data on the possible side effects and doses in humans are needed. The hope is that DGXB could eventually be used against AA in modern complementary and alternative immunosuppressive therapeutics.