Inhibition of innate immune activation by modifications in bacterial RNA

Modification of RNA is an important function in the immunological discrimination between self and non-self RNA. Naturally occurring RNA modifications have been identified that suppress activation of the innate immune response, e.g. 2’O-methylation of the ribose backbone. It has already been shown that incorporation of 2’O-methylation in siRNA abrogates TLR7-dependent interferon-alpha production in human plasmacytoid dendritic cells (pDCs). In the present study, a native bacterial tRNA with 2’O-methylation at position G18 was analysed. It was found that the 2’O-methylation not only made the tRNA non-stimulatory, but also led to dominant inhibitory effects. Thus, this modification impaired immunostimulation by RNA species that would otherwise have been stimulatory. Further analysis revealed that not only was interferon alpha production by pDCs via TLR7 suppressed, but also secretion of pro-inflammatory cytokines by monocytes, including IL12p40 and TNF. Monocytes express a different subset of nucleic acid-sensing receptors, indicating that 2’O-methylated RNA influences the stimulation of different receptors. Analysis of other TLR ligands showed that the inhibitory effect was specific for stimulation by RNA but it was not observed for R848, a synthetic small molecule agonist of TLR7/8, or other TLR ligands. Investigation of the signalling pathway in response to RNA stimulation showed that modified, inhibitory RNA suppresses TLR stimulation at proximal levels. Preliminary binding studies indicated that 2’O-methylated RNA can bind directly to TLR7; it does not induce signalling but displaces unmethylated stimulatory RNA. As 2’O-methylation of tRNA at position G18 is found in tRNAs from many species and the neighbouring sequences are conserved, the influence of location and the whole sequence motif itself were investigated. The location of the 2’O-modification turned out to be of minor importance, but the inhibitory capacity of modified tRNA was influenced by the sequence of the motif. The sequence motif DmR was found to be necessary for immunosilencing of the tRNA, where D is a base other than cytosine with a 2’O-methyl position in the ribose of the nucleoside and R is a purine (adenine or guanine) immediately upstream of the methylation (position +1). Together, the results show that 2’O-methylation of RNA in a defined sequence motif abrogates immunostimulation in different cell types. Naturally occurring RNA modifications serve to distinguish self RNA from foreign RNA. The results from this thesis can be used to reduce immunostimulation by any RNA when immune stimulation is not intended

Lithium Content of 160 Beverages and Its Impact on Lithium Status in Drosophila melanogaster

Lithium (Li) is an important micronutrient in human nutrition, although its exact molecular function as a potential essential trace element has not yet been fully elucidated. It has been previously shown that several mineral waters are rich and highly bioavailable sources of Li for human consumption. Nevertheless, little is known about the extent in which other beverages contribute to the dietary Li supply. To this end, the Li content of 160 different beverages comprising wine and beer, soft and energy drinks and tea and coffee infusions was analysed by inductively coupled plasma mass spectrometry (ICP-MS). Furthermore, a feeding study in Drosophila melanogaster was conducted to test whether Li derived from selected beverages changes Li status in flies. In comparison to the average Li concentration in mineral waters (108 µg/L; reference value), the Li concentration in wine (11.6 ± 1.97 µg/L) and beer (8.5 ± 0.77 µg/L), soft and energy drinks (10.2 ± 2.95 µg/L), tea (2.8 ± 0.65 µg/L) and coffee (0.1 ± 0.02 µg/L) infusions was considerably lower. Only Li-rich mineral water (~1600 µg/L) significantly increased Li concentrations in male and female flies. Unlike mineral water, most wine and beer, soft and energy drink and tea and coffee samples were rather Li-poor food items and thus may only contribute to a moderate extent to the dietary Li supply. A novelty of this study is that it relates analytical Li concentrations in beverages to Li whole body retention in Drosophila melanogaster

A Natural mtDNA Polymorphism in Complex III Is a Modifier of Healthspan in Mice

In this study, we provide experimental evidence that a maternally inherited polymorphism in the mitochondrial cytochrome b gene (mt-Cytb; m.15124A>G, Ile-Val) in mitochondrial complex III resulted in middle-aged obesity and higher susceptibility to diet-induced obesity, as well as age-related inflammatory disease, e.g., ulcerative dermatitis, in mice. As a consequence of the gene variation, we observed alterations in body composition, metabolism and mitochondrial functions, i.e., increased mitochondrial oxygen consumption rate and higher levels of reactive oxygen species, as well as in the commensal bacterial composition in the gut, with higher abundance of Proteobacteria in mice carrying the variant. These observations are in line with the previously described links of the mitochondrial complex III gene with obesity and metabolic diseases in humans. Given that these functional changes by the G variant at m.15124 in the mt-Cytb are already present in young mice that were kept under normal condition, it is plausible that the m.15124A>G variant is a disease susceptibility modifier to the diseases induced by additional stressors, i.e., dietary and/or aging stress, and that the variant results in the higher incidence of clinical diseases presentation in C57BL/6J-mt129S1/SvlmJ than C57BL/6J mice. Thus, mtDNA variants could be potential biomarkers to evaluate the healthspan

Boron Contents of German Mineral and Medicinal Waters and Their Bioavailability in Drosophila melanogaster and Humans

Scope Boron is a trace element that naturally occurs in soil, making mineral and medicinal water important contributors to overall intake. Thus, in a systematic screening, the mean boron concentrations of 381 German mineral and medicinal waters are determined. Methods and results Boron concentrations in mineral and medicinal waters are analyzed by inductively coupled mass spectrometry (ICP-MS). Highest boron values find in waters from the southwest of Germany. The boron content of the waters is positively correlated with the concentration of most other analyzed bulk elements, including calcium, potassium, magnesium, and sodium. Mineral waters with either low (7.9 µg L-1 ), medium (113.9 µg L-1 ), or high (2193.3 µg L-1 ) boron content are chosen for boron exposure experiments in fruit flies (Drosophila melanogaster) and humans. In flies, boron-rich mineral water significantly increases boron accumulation, with the accumulation predominantly occurring in the exoskeleton. In humans, serum boron and 24-h urinary boron excretion significantly increase only in response to the intake of boron-rich mineral water. Conclusion Overall, the current data demonstrate that mineral and medicinal waters vary substantially in the content of boron and that boron-rich mineral water can be used to elevate the boron status, both in flies and humans

Diagnosis and Therapy of Female Genital Malformations (Part 2). Guideline of the DGGG, OEGGG and SGGG (S2k Level, AWMF Registry Number 015/052, May 2019).

Objectives Female genital malformations may be present in the form of individual entities, they may involve neighboring organs or they may occur in the context of complex syndromes. Given the anatomical structures of the vulva, vagina, uterus and uterine appendages, the clinical picture of malformations varies greatly. Methods This S2k-guideline was developed by representative members from different medical specialties and professions as part of the guidelines program of the DGGG, SGGG and OEGGG. The recommendations and statements were developed and voted on using a structured consensus process with neutral moderation. Recommendations This guideline is the first comprehensive summary of female genital malformations from infancy to adulthood which covers clinical examinations, diagnostic workups and treatment options. Additional chapters have been included on complex urogenital malformations, vascular malformations, psychosomatic care, and tumor risk

Diagnosis and Therapy of Female Genital Malformations (Part 1). Guideline of the DGGG, OEGGG and SGGG (S2k Level, AWMF Registry Number 015/052, May 2019).

Objectives Female genital malformations may take the form of individual entities, they may involve neighboring organs or they may occur in the context of complex syndromes. Given the anatomical structures of the vulva, vagina, uterus and adnexa, the clinical picture of malformations may vary greatly. Depending on the extent of the malformation, organs of the urinary system or associated malformations may also be involved. Methods This S2k-guideline was developed by representative members from different medical specialties and professions as part of the guidelines program of the DGGG, SGGG and OEGGG. The recommendations and statements were developed using a structured consensus process with neutral moderation and voted on. Recommendations The guideline is the first comprehensive presentation of the symptoms, diagnosis and treatment options for female genital malformations. Additional chapters on classifications and transition were included

Metabolic Signature of Electrosurgical Liver Dissection

<div><p>Background and Aims</p><p>High frequency electrosurgery has a key role in the broadening application of liver surgery. Its molecular signature, <i>i.e.</i> the metabolites evolving from electrocauterization which may inhibit hepatic wound healing, have not been systematically studied.</p><p>Methods</p><p>Human liver samples were thus obtained during surgery before and after electrosurgical dissection and subjected to a two-stage metabolomic screening experiment (discovery sample: N = 18, replication sample: N = 20) using gas chromatography/mass spectrometry.</p><p>Results</p><p>In a set of 208 chemically defined metabolites, electrosurgical dissection lead to a distinct metabolic signature resulting in a separation in the first two dimensions of a principal components analysis. Six metabolites including glycolic acid, azelaic acid, 2-n-pentylfuran, dihydroactinidiolide, 2-butenal and n-pentanal were consistently increased after electrosurgery meeting the discovery (p<2.0×10⁻⁴) and the replication thresholds (p<3.5×10⁻³). Azelaic acid, a lipid peroxidation product from the fragmentation of abundant sn-2 linoleoyl residues, was most abundant and increased 8.1-fold after electrosurgical liver dissection (p_replication = 1.6×10⁻⁴). The corresponding phospholipid hexadecyl azelaoyl glycerophosphocholine inhibited wound healing and tissue remodelling in scratch- and proliferation assays of hepatic stellate cells and cholangiocytes, and caused apoptosis dose-dependently <i>in vitro</i>, which may explain in part the tissue damage due to electrosurgery.</p><p>Conclusion</p><p>Hepatic electrosurgery generates a metabolic signature with characteristic lipid peroxidation products. Among these, azelaic acid shows a dose-dependent toxicity in liver cells and inhibits wound healing. These observations potentially pave the way for pharmacological intervention prior liver surgery to modify the metabolic response and prevent postoperative complications.</p></div