Cell-free DNA-induced alteration of autophagy response and TLR9-signaling: Their relation to amelioration of DSS-colitis.

BACKGROUND: The influence of cell-free DNA (fDNA) administration on the TLR9-autophagy regulatory crosstalk within inflammatory circumstances remains unclear. AIMS: To examine the immunobiologic effects of iv. fDNA injection on the TLR9-mediated autophagy response in murine DSS-colitis. METHODS: Different types of modified fDNAs were administered to DSS-colitic mice. Disease and histological activities, spleen index were measured. Changes of the TLR9-associated and autophagy-related gene expression profiles of lamina proprial cells and splenocytes were assayed by quantitative real-time PCR, and validated by immunohistochemistries. Ultrastructural changes of the colon were examined by transmission electron microscopy (TEM). RESULTS: A single intravenous injection of colitic fDNA (C-DNA) exhibited beneficial clinical and histological effects on DSS-colitis, compared to normal (N-DNA). C-DNA administration displayed a more prominent impact on the outcome of the TLR9-autophagy response than N-DNA. C-DNA resulted in a decreased spleen index in DSS-colitic mice. C-DNA treatment of normal mice resulted in a downregulation of Beclin1 and ATG16L1 mRNA and protein expression in the colon. These as well as LC3B were downregulated in the spleen. In contrast, the Beclin1, ATG16L1 and LC3B gene and protein expressions were upregulated in both the colon and the spleen by C-DNA injection. Moreover, C-DNA administration to DSS-colitic mice resulted in a remarkable increase of epithelial autophagic vacuoles representing an intensified macroautophagy. CONCLUSIONS: The effect of intravenously administered fDNA on the TLR9-mediated autophagy response is expressly dependent on the origin of fDNA (i.e. inflammatory or not) and on the characteristics of the local immunobiologic milieu (i.e. inflammatory or not, as well).

Fetal DNA does not induce preeclampsia-like symptoms when delivered in late pregnancy in the mouse.

INTRODUCTION: The etiology of preeclampsia is unclear. Fetal DNA is present in higher concentrations in the plasma of pregnant women suffering from preeclampsia than in the plasma of healthy pregnant women. A previously published study has shown that human fetal DNA injected into pregnant mice induces preeclampsia-like symptoms when administered between gestation days 10-14. The aim of our experiment was to determine whether or not similar effects would be induced by administration of human and mouse fetal DNA, as well as mouse adult DNA and lipopolysaccharide during late pregnancy in the mouse. METHODS: Experimental animals were injected daily intraperitoneally during gestation days 14-18 with either saline - negative control, lipopolysaccharide - positive control, or various types of DNA. On gestation day 19, blood pressure and proteinuria were measured, and placental and fetal weights were recorded. RESULTS: Fetal and placental hypotrophy were induced only by lipopolysaccharide (p < 0.001). Neither fetal nor adult DNA induced changes in fetal/placental weight. None of the experimental groups had higher blood pressure or urinary protein in comparison to saline treated animals. DISCUSSION: In our experiment, we found that there was no effect from intraperitoneally injected human fetal DNA, mouse fetal DNA, or mouse adult DNA on pregnant mice. Additionally, relatively high doses of various types of DNA did not induce preeclampsia-like symptoms in mice when administered in late pregnancy. Our negative results support the hypothesis that the increase of fetal DNA circulating in maternal circulation during the third trimester is rather a consequence than a cause of preeclampsia.