Interleukin-10 suppression enhances T-cell antitumor immunity and responses to checkpoint blockade in chronic lymphocytic leukemia.

T-cell dysfunction is a hallmark of B-cell Chronic Lymphocytic Leukemia (CLL), where CLL cells downregulate T-cell responses through regulatory molecules including programmed death ligand-1 (PD-L1) and Interleukin-10 (IL-10). Immune checkpoint blockade (ICB) aims to restore T-cell function by preventing the ligation of inhibitory receptors like PD-1. However, most CLL patients do not respond well to this therapy. Thus, we investigated whether IL-10 suppression could enhance antitumor T-cell activity and responses to ICB. Since CLL IL-10 expression depends on Sp1, we utilized a novel, better tolerated analogue of the Sp1 inhibitor mithramycin (MTMox32E) to suppress CLL IL-10. MTMox32E treatment inhibited mouse and human CLL IL-10 production and maintained T-cell effector function in vitro. In the Eµ-Tcl1 mouse model, treatment reduced plasma IL-10 and CLL burden and increased CD8+ T-cell proliferation, effector and memory cell prevalence, and interferon-γ production. When combined with ICB, suppression of IL-10 improved responses to anti-PD-L1 as shown by a 4.5-fold decrease in CLL cell burden compared to anti-PD-L1 alone. Combination therapy also produced more interferon-γ+, cytotoxic effector KLRG1+, and memory CD8+ T-cells, and fewer exhausted T-cells. Since current therapies for CLL do not target IL-10, this provides a novel strategy to improve immunotherapies.

Bioactive benzopyrone derivatives from new recombinant fusant of marine Streptomyces.

In our searching program for bioactive secondary metabolites from marine Streptomycetes, three microbial benzopyrone derivatives (1-3), 7-methylcoumarin (1) and two flavonoides, rhamnazin (2) and cirsimaritin (3), were obtained during the working up of the ethyl acetate fraction of a marine Streptomyces fusant obtained from protoplast fusion between Streptomyces strains Merv 1996 and Merv 7409. The structures of the three compounds (1-3) were established by nuclear magnetic resonance, mass, UV spectra, and by comparison with literature data. Marine Streptomyces strains were identified based on their phenotypic and chemotypic characteristics as two different bioactive strains of the genus Streptomyces. We described here the fermentation, isolation, as well as the biological activity of these bioactive compounds. The isolated compounds (1-3) are reported here as microbial products for the first time.

The Electrospray Ionization - Mass Spectra of Erythromycin A Obtained from a Marine Streptomyces sp. Mutant.

In our ongoing search for production improvements of bioactive secondary metabolites from marine Streptomyces through the induction of mutations using UV light, out of 145 isolates, mutant 10/14 was able to produce potent antibacterial metabolites other than the parent strain as established by chromatographic analysis. Up-scaling fermentation of mutant 10/14, followed by working up and isolation delivered five metabolites, phenazine, 1-acetyl-beta -carboline, perlolyrin and erythromycin A, along with an oily substance. The latter two compounds were responsible for the antibacterial activity of the strain. In this article, we discuss with the mutation of the marine Streptomyces sp. AH2, bioactivity evaluation, fermentation and isolation of the microbial metabolites. Moreover, we study to first time in detail the 1D and 2D NMR and ESI MS data including ESI MS(2) and MS(3) patterns combined with HRESI MS of erythromycin A.