Anti-miR-93-5p therapy prolongs sepsis survival by restoring the peripheral immune response

Sepsis remains a leading cause of human death and currently has no pathogenesis-specific therapy. Hampered progress is partly due to a lack of insight into deep mechanistic processes. In the last decade, deciphering the functions of small non-coding microRNAs (miRNAs) in sepsis pathogenesis became a dynamic research topic. To screen for new miRNA targets for sepsis therapeutics, we used human samples for miRNA array from peripheral blood mononuclear cells from sepsis patients and controls, blood samples from two cohorts of sepsis patients, and multiple animal models: mouse cecum ligation-puncture (CLP)-induced sepsis, mouse viral miRNA challenge, and baboon Gram-positive and Gram-negative sepsis models. miR-93-5p met the criteria for a therapeutic target, being overexpressed in baboons that died early after induction of sepsis, downregulated in humans who survived after sepsis, and correlated with negative clinical prognosticators for sepsis. Therapeutically, inhibiting miR-93-5p prolonged the overall survival of mice with CLP-induced sepsis, with a stronger effect in older mice. Mechanistically, anti-miR-93-5p therapy reduced inflammatory monocytes and increased circulating effector memory T cells, especially the CD4+ subset. AGO2-immunoprecipitation in miR-93-knockout T cells identified important regulatory receptors, such as CD28, as direct miR-93-5p target genes. In conclusion, miR-93-5p is a potential therapeutic target in sepsis through regulating both innate and adaptive immunity with possibly more benefit for the elderly than the young patients.

Trabectedin Reveals a Strategy of Immunomodulation in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is a B-cell neoplasia characterized by protumor immune dysregulation involving nonmalignant cells of the microenvironment, including T lymphocytes and tumor-associated myeloid cells. Although therapeutic agents have improved treatment options for CLL, many patients still fail to respond. Some patients also show immunosuppression. We have investigated trabectedin, a marine-derived compound with cytotoxic activity on macrophages in solid tumors. Here, we demonstrate that trabectedin induces apoptosis of human primary leukemic cells and also selected myeloid and lymphoid immunosuppressive cells, mainly through the TRAIL/TNF pathway. Trabectedin modulates transcription and translation of IL6, CCL2, and IFNα in myeloid cells and FOXP3 in regulatory T cells. Human memory CD8⁺ T cells downregulate PD-1 and, along with monocytes, exert in vivo antitumor function. In xenograft and immunocompetent CLL mouse models, trabectedin has antileukemic effects and antitumor impact on the myeloid and lymphoid cells compartment. It depletes myeloid-derived suppressor cells and tumor-associated macrophages and increases memory T cells. Trabectedin also blocks the PD-1/PD-L1 axis by targeting PD-L1⁺ CLL cells, PD-L1⁺ monocytes/macrophages, and PD-1⁺ T cells. Thus, trabectedin behaves as an immunomodulatory drug with potentially attractive therapeutic value in the subversion of the protumor microenvironment and in overcoming chemoimmune resistance.

An overview of chronic lymphocytic leukaemia biology

Chronic lymphocytic leukaemia (CLL) is characterised by accumulation of CD5(+) monoclonal B cells in primary and secondary lymphoid tissues. Genetic defects and stimuli originating from the microenvironment concur to the selection and expansion of the malignant clone. Several lines of evidence, including molecular and functional analysis of the monoclonal immunoglobulin, support the hypothesis that stimulation through the B-cell receptor affects life and death of leukaemic cells. The microenvironment also has a critical role in the survival and accumulation of leukaemic cells within lymphoid organs where signals delivered from the surrounding cells are likely crucial in inducing proliferation. Nevertheless, several major biological issues still remain to be solved including regulation of the balance between proliferation and survival of leukaemic cells and the links between emerging gene abnormalities and microenvironment. In this context, mouse models are helpful tools in understanding disease mechanisms and in evaluating the efficacy of novel therapeutic agents.