Macrophage Modification Strategies for Efficient Cell Therapy.

Macrophages, important cells of innate immunity, are known for their phagocytic activity, capability for antigen presentation, and flexible phenotypes. Macrophages are found in all tissues and therefore represent an attractive therapeutic target for the treatment of diseases of various etiology. Genetic programming of macrophages is an important issue of modern molecular and cellular medicine. The controllable activation of macrophages towards desirable phenotypes in vivo and in vitro will provide effective treatments for a number of inflammatory and proliferative diseases. This review is focused on the methods for specific alteration of gene expression in macrophages, including the controllable promotion of the desired M1 (pro-inflammatory) or M2 (anti-inflammatory) phenotypes in certain pathologies or model systems. Here we review the strategies of target selection, the methods of vector delivery, and the gene editing approaches used for modification of macrophages.

Molecular mechanisms of splenectomy-induced hepatocyte proliferation.

Functional and anatomical connection between the liver and the spleen is most clearly manifested in various pathological conditions of the liver (cirrhosis, hepatitis). The mechanisms of the interaction between the two organs are still poorly understood, as there have been practically no studies on the influence exerted by the spleen on the normal liver. Mature male Sprague-Dawley rats of 250-260 g body weight, 3 months old, were splenectomized. The highest numbers of Ki67+ hepatocytes in the liver of splenectomized rats were observed at 24 h after the surgery, simultaneously with the highest index of Ki67-positive hepatocytes. After surgical removal of the spleen, expression of certain genes in the liver tissues increased. A number of genes were upregulated in the liver at a single time point of 24 h, including Ccne1, Egf, Tnfa, Il6, Hgf, Met, Tgfb1r2 and Nos2. The expression of Ccnd1, Tgfb1, Tgfb1r1 and Il10 in the liver was upregulated over the course of 3 days after splenectomy. Monitoring of the liver macrophage populations in splenectomized animals revealed a statistically significant increase in the proportion of CD68-positive cells in the liver (as compared with sham-operated controls) detectable at 24 h and 48 h after the surgery. The difference in the liver content of CD68-positive cells between splenectomized and sham-operated animals evened out by day 3 after the surgery. No alterations in the liver content of CD163-positive cells were observed in the experiments. A decrease in the proportion of CD206-positive liver macrophages was observed at 48 h after splenectomy. The splenectomy-induced hepatocyte proliferation is described by us for the first time. Mechanistically, the effect is apparently induced by the removal of spleen as a major source of Tgfb1 (hepatocyte growth inhibitor) and subsequently supported by activation of proliferation factor-encoding genes in the liver.

Yb body assembly on the flamenco piRNA precursor transcripts reduces genic piRNA production.

In Drosophila ovarian somatic cells, PIWI-interacting small RNAs (piRNAs) against transposable elements are mainly produced from the ∼180-kb flamenco (flam) locus. flam transcripts are gathered into foci, located close to the nuclear envelope, and processed into piRNAs in the cytoplasmic Yb bodies. The mechanism of Yb body formation remains unknown. Using RNA fluorescence in situ hybridization, we found that in the follicle cells of ovaries the 5'-ends of flam transcripts are usually located in close proximity to the nuclear envelope and outside of Yb bodies, whereas their extended downstream regions mostly overlap with Yb bodies. In flamKG mutant ovaries, flam transcripts containing the first and, partially, second exons but lacking downstream regions are gathered into foci at the nuclear envelope, but Yb bodies are not assembled. Strikingly, piRNAs from the protein-coding gene transcripts accumulate at higher levels in flamKG ovaries indicating that piRNA biogenesis may occur without Yb bodies. We propose that normally in follicle cells, flam downstream transcript regions function not only as a substrate for generation of piRNAs but also as a scaffold for Yb body assembly, which competitively decreases piRNA production from the protein-coding gene transcripts. By contrast, in ovarian somatic cap and escort cells Yb body assembly does not require flam transcription.