Exosome and Microvesicle-Enriched Fractions Isolated from Mesenchymal Stem Cells by Gradient Separation Showed Different Molecular Signatures and Functions on Renal Tubular Epithelial Cells.

Several studies have suggested that extracellular vesicles (EVs) released from mesenchymal stem cells (MSCs) may mediate MSC paracrine action on kidney regeneration. This activity has been, at least in part, ascribed to the transfer of proteins/transcription factors and different RNA species. Information on the RNA/protein content of different MSC EV subpopulations and the correlation with their biological activity is currently incomplete. The aim of this study was to evaluate the molecular composition and the functional properties on renal target cells of MSC EV sub-populations separated by gradient floatation. The results demonstrated heterogeneity in quantity and composition of MSC EVs. Two peaks of diameter were observed (90-110 and 170-190 nm). The distribution of exosomal markers and miRNAs evaluated in the twelve gradient fractions showed an enrichment in fractions with a flotation density of 1.08-1.14 g/mL. Based on this observation, we evaluated the biological activity on renal cell proliferation and apoptosis resistance of low (CF1), medium (CF2) and high (CF3) floatation density fractions. EVs derived from all fractions, were internalized by renal cells, CF1 and CF2 but not CF3 fraction stimulated significant cell proliferation. CF2 also inhibited apoptosis on renal tubular cells submitted to ischemia-reperfusion injury. Comparative miRNomic and proteomic profiles reveal a cluster of miRNAs and proteins common to all three fractions and an enrichment of selected molecules related to renal regeneration in CF2 fraction. In conclusion, the CF2 fraction enriched in exosomal markers was the most active on renal tubular cell proliferation and protection from apoptosis.

Secretion of matrix metalloproteinase-9 by macrophages, in vitro, in response to Helicobacter pylori.

We have previously shown that matrix metalloproteinase-9 (MMP-9) activity is greatly enhanced within the active chronic inflammation of Helicobacter pylori infected individuals, of which a major fraction derives from macrophages in the tissue. Here, we have investigated the ability of macrophages to secrete MMPs in response to H. pylori. Human macrophages secrete MMP-9 in response to live and inactivated H. pylori, as well as to specific bacterial products. Protein kinase C, phosphatiolylinositol 3-kinase and calcium uptake channels all play a role in MMP-9 secretion, whereas neither tumour necrosis factor alpha, interleukin-8, nor interleukin-1beta autocrine stimulation appear to contribute. We conclude that human macrophages have the ability to react directly against several H. pylori derived factors, utilising several signalling pathways.

Increased production of matrix metalloproteinases in Helicobacter pylori-associated human gastritis.

BACKGROUND AND AIMS: Helicobacter pylori infection results in an active, chronic inflammation of the gastric mucosa. Previous studies have highlighted the importance of matrix metalloproteinases (MMPs) in diseases involving mucosal inflammation, prompting us to investigate MMP activity in H. pylori-induced gastritis. METHODS: Gastric biopsies were obtained from H. pylori-infected and uninfected volunteers, and MMP activity was assessed using substrate gel electrophoresis. MMP production was also evaluated by immunohistochemistry and real time-polymerase chain reaction. In parallel, tissue inhibitors of MMPs (TIMP) levels and TIMP-MMP complexes were examined in corresponding tissues using enzyme-linked immunosorbent assays and Western blotting. Finally, MMP production by gastric macrophages was determined after stimulation with H. pylori. RESULTS: Antral mucosa of H. pylori-infected subjects demonstrated a 19-fold higher MMP-9 activity than that of uninfected individuals. MMP-2 was present at lower levels, but was also increased in H. pylori-infected individuals, while there was no difference in the total levels of TIMP-1 and TIMP-2 between the groups of volunteers. Significant numbers of MMP-9-containing cells were only found in the H. pylori-infected antral mucosa. Tissue-resident macrophages were significantly increased in H. pylori-infected individuals, and double-staining showed MMP-9 colocalized to macrophages. Furthermore, gastric macrophages secreted MMP-9 in response to H. pylori bacteria. A corresponding 10-fold increase of gene expression of MMP-9 was seen in patients infected with H. pylori compared to uninfected individuals. CONCLUSIONS: Helicobacter pylori infection results in a substantial increase in MMP-9 and MMP-2 activity in the gastric mucosa, probably contributed to in large part by tissue-resident macrophages, while no changes were seen in the TIMP levels. The net increase in gastric MMP activity is likely to contribute to tissue damage during H. pylori-associated gastritis.