Adenosine-Metabolizing Enzymes, Adenosine Kinase and Adenosine Deaminase, in Cancer.

The immunosuppressive effect of adenosine in the microenvironment of a tumor is well established. Presently, researchers are developing approaches in immune therapy that target inhibition of adenosine or its signaling such as CD39 or CD73 inhibiting antibodies or adenosine A2A receptor antagonists. However, numerous enzymatic pathways that control ATP-adenosine balance, as well as understudied intracellular adenosine regulation, can prevent successful immunotherapy. This review contains the latest data on two adenosine-lowering enzymes: adenosine kinase (ADK) and adenosine deaminase (ADA). ADK deletes adenosine by its phosphorylation into 5'-adenosine monophosphate. Recent studies have revealed an association between a long nuclear ADK isoform and an increase in global DNA methylation, which explains epigenetic receptor-independent role of adenosine. ADA regulates the level of adenosine by converting it to inosine. The changes in the activity of ADA are detected in patients with various cancer types. The article focuses on the biological significance of these enzymes and their roles in the development of cancer. Perspectives of future studies on these enzymes in therapy for cancer are discussed.

Targeting regulatory T cells in anti-PD-1/PD-L1 cancer immunotherapy.

The programmed death (PD)-1/PD-ligand (PD-L) pathway and regulatory T cells (Tregs) are essential for the maintenance of immune tolerance. Their activation in the tumour microenvironment contributes to the evasion of the transformed cells from the immune surveillance and the suppression of an antitumour immune response. Therefore, PD-1/PD-L1 and Tregs are important targets for cancer immunotherapy. Our review focuses on the current role of the PD-1/PD-L1 axis in Treg development and function in the tumour microenvironment. We also discuss combination therapy with PD-1/PD-L1 inhibitors and Treg-modulating agents affecting the adenosinergic pathway, TGF-ß signalling, immune checkpoints and other approaches to downregulation of Tregs.

MicroRNAs in rheumatoid arthritis: altered expression and diagnostic potential.

Rheumatoid arthritis (RA) is a polygenic disease characterized by autoimmunity and systemic inflammation with progressive impairment of joints that results in lifelong disability and increased mortality. Early diagnosis and therapeutic intervention or treatment can prevent severe disease manifestations in patients suffering from RA. The use of appropriate predictive biomarkers may improve the efficiency of RA therapy. The general aim of this review is to highlight the most recent findings on miRNAs expression profiles in RA patients and to discuss their potential as new biomarkers for diagnostic purposes. The current literature demonstrates that a variety of miRNAs is frequently dysregulated in RA patients. To date, the majority of miRNAs have been found to be overexpressed during the natural course of RA. MiR-16, miR-146a/b, miR-150, miR-155, and miR-223 described here were shown to be overexpressed at the systemic level: in both the periphery and RA joints. Circulating peripheral blood miRNAs, especially miR-16, miR-21, miR-24, miR-26a, miR-125a-5p, miR-125b, miR-126-3p, miR-223, and miR-451, which are elevated in the plasma or serum, are considered to be the most promising non-invasive biomarkers for the detection of RA.

A novel method of modifying immune responses by vaccination with lipiodol-siRNA mixtures.

The dendritic cell (DC) possesses the ability to stimulate both T helper 1 (Th1) and Th2 responses depending on activation stimuli. Although it is known that chemically or genetically modified DC can be used therapeutically to steer immune responses towards either Th1 or Th2, cellular therapy with ex vivo manipulated DC is clinically difficult. Here we demonstrate a novel method of switching immune responses from Th1 to Th2 through in vivo immune modulation by administration of siRNA. We demonstrate that siRNA targeting of the IL-12p35 gene leads to a Th2 bias in vitro through an IL-10 dependent mechanism. In vivo administration of siRNA admixed with the oil-based contrast agent lipiodol in the presence of antigen and adjuvant induced a deviation in recall response to reduced production of IFN-gamma and augmented IL-4 response using either KLH or ovalbumin. This simple method of in vivo modification of immune response possesses therapeutic potential in Th1-mediated diseases such as multiple sclerosis and autoimmune diabetes.