MicroRNA-155 Deficiency Exacerbates Trypanosoma cruzi Infection.

Chagas disease, caused by the intracellular protozoan parasite Trypanosoma cruzi, is a public health problem affecting 6 to 8 million people, mainly in Latin America. The role of microRNAs in the pathogenesis of Chagas disease has not been well described. Here, we investigate the role of microRNA-155 (miR-155), a proinflammatory host innate immune regulator responsible for T helper type 1 and type 17 (Th1 and Th17) development and macrophage responses during T. cruzi infection. For this, we compared the survival and parasite growth and distribution in miR-155-/- and wild-type (WT) C57BL/6 mice. The lack of miR-155 caused robust parasite infection and diminished survival of infected mice, while WT mice were resistant to infection. Immunological analysis of infected mice indicated that, in the absence of miR-155, there was decreased interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) production. In addition, we found that there was a significant reduction of CD8-positive (CD8+) T cells, natural killer (NK) cells, and NK-T cells and increased accumulation of neutrophils and inflammatory monocytes in miR-155-/- mice. Collectively, these data indicate that miR-155 is an important immune regulatory molecule critical for the control of T. cruzi infection.

Ibrutinib treatment inhibits breast cancer progression and metastasis by inducing conversion of myeloid-derived suppressor cells to dendritic cells.

BACKGROUND: Ibrutinib is a Bruton's tyrosine kinase (BTK) and interleukin-2-inducible kinase (ITK) inhibitor used for treating chronic lymphocytic leukaemia (CLL) and other cancers. Although ibrutinib is known to inhibit the growth of breast cancer cell growth in vitro, its impact on the treatment and metastasis of breast cancer is unclear. METHODS: Using an orthotopic mouse breast cancer model, we show that ibrutinib inhibits the progression and metastasis of breast cancer. RESULTS: Ibrutinib inhibited proliferation of cancer cells in vitro, and Ibrutinib-treated mice displayed significantly lower tumour burdens and metastasis compared to controls. Furthermore, the spleens and tumours from Ibrutinib-treated mice contained more mature DCs and lower numbers of myeloid-derived suppressor cells (MDSCs), which promote disease progression and are linked to poor prognosis. We also confirmed that ex vivo treatment of MDSCs with ibrutinib switched their phenotype to mature DCs and significantly enhanced MHCII expression. Further, ibrutinib treatment promoted T cell proliferation and effector functions leading to the induction of antitumour TH1 and CTL immune responses. CONCLUSIONS: Ibrutinib inhibits tumour development and metastasis in breast cancer by promoting the development of mature DCs from MDSCs and hence could be a novel therapeutic agent for the treatment of breast cancer.