Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity.

Non-toxic approaches to enhance radiotherapy outcomes are beneficial, particularly in ageing populations. Based on preclinical findings showing that high-fibre diets sensitised bladder tumours to irradiation by modifying the gut microbiota, along with clinical evidence of prebiotics enhancing anti-cancer immunity, we hypothesised that dietary fibre and its gut microbiota modification can radiosensitise tumours via secretion of metabolites and/or immunomodulation. We investigated the efficacy of high-fibre diets combined with irradiation in immunoproficient C57BL/6 mice bearing bladder cancer flank allografts. Psyllium plus inulin significantly decreased tumour size and delayed tumour growth following irradiation compared to 0.2% cellulose and raised intratumoural CD8+ cells. Post-irradiation, tumour control positively correlated with Lachnospiraceae family abundance. Psyllium plus resistant starch radiosensitised the tumours, positively correlating with Bacteroides genus abundance and increased caecal isoferulic acid levels, associated with a favourable response in terms of tumour control. Psyllium plus inulin mitigated the acute radiation injury caused by 14 Gy. Psyllium plus inulin increased caecal acetate, butyrate and propionate levels, and psyllium alone and psyllium plus resistant starch increased acetate levels. Human gut microbiota profiles at the phylum level were generally more like mouse 0.2% cellulose profiles than high fibre profiles. These supplements may be useful in combination with radiotherapy in patients with pelvic malignancy

Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity

Acknowledgements We thank Professor William Kim (University of North Carolina, Chapel Hill) for his generous gift of the UPPL1591 cell line. We thank Dr. Mark Hill (Department of Oncology, University of Oxford) for assistance with irradiation procedures, and Dr. Jia-Yu Ke and Dr. Vijay Indukuri (Research Diets, Inc.) for formulation of the mouse diets. We thank Dr. Graham Horgan (James Hutton Research Institute, Aberdeen) for statistical advice. We thank Grampian Biorepository at Aberdeen Royal Infirmary for providing the faecal samples from cancer patients.Peer reviewe

Oxylipin metabolism is controlled by mitochondrial β-oxidation during bacterial inflammation

Oxylipins are potent biological mediators requiring strict control, but how they are removed en masse during infection and inflammation is unknown. Here we show that lipopolysaccharide (LPS) dynamically enhances oxylipin removal via mitochondrial β-oxidation. Specifically, genetic or pharmacological targeting of carnitine palmitoyl transferase 1 (CPT1), a mitochondrial importer of fatty acids, reveal that many oxylipins are removed by this protein during inflammation in vitro and in vivo. Using stable isotope-tracing lipidomics, we find secretion-reuptake recycling for 12-HETE and its intermediate metabolites. Meanwhile, oxylipin β-oxidation is uncoupled from oxidative phosphorylation, thus not contributing to energy generation. Testing for genetic control checkpoints, transcriptional interrogation of human neonatal sepsis finds upregulation of many genes involved in mitochondrial removal of long-chain fatty acyls, such as ACSL1,3,4, ACADVL, CPT1B, CPT2 and HADHB. Also, ACSL1/Acsl1 upregulation is consistently observed following the treatment of human/murine macrophages with LPS and IFN-γ. Last, dampening oxylipin levels by β-oxidation is suggested to impact on their regulation of leukocyte functions. In summary, we propose mitochondrial β-oxidation as a regulatory metabolic checkpoint for oxylipins during inflammation

Characterization of c-Jun N-terminal kinase 1 (JNK1) – subcellular localization, post-translational modifications and protein complexes under control and stress conditions

© 2013 Dr. Mariya Mishevac-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase (MAPK) subfamily of protein kinases involved in a number of biological processes such as programmed cell death, cell survival, development and the inflammatory response. The role of JNKs in this diverse range of processes has continued to attract attention. The numerous investigations undertaken since their discovery in the early 1990s have led to the identification of multiple substrates localized in the nucleus, the cytoplasm and the mitochondria, as well as regulators of the JNK signaling pathway (scaffolds, upstream kinases and downstream phosphatases). In addition, the involvement of JNKs in both physiological and pathological processes in the cell has been investigated in more detail by studies in knockout animals. The accumulated evidence points to the different JNK isoforms having both redundant and specific functions in a number of biological processes under basal conditions and upon stimulation. The function of the different JNK isoforms may therefore be both cell type- and stress stimulus-specific. In addition, the reported data implies that JNK1 is the main contributor to the development of pathophysiological processes. However, despite this growing knowledge on the JNK signaling pathway, the precise mechanisms underlying their regulation in the cell still requires more detailed evaluation. Thus, this thesis has explored specifically the subcellular localization, the post-translational modifications and the proteins associated with JNK1 in the absence of stress and following stress treatment. This work presents the first live cell imaging and fluorescence recovery after photobleaching (FRAP) analyses for JNK, and has revealed that JNK1α1 is exchanged between and within the nucleus and the cytoplasm under basal conditions. Contrary to expectations for JNK1 as a stress-activated kinase, hyperosmotic stress treatment slows the rate of kinetics of JNK1 movement within the cell. These observations led to further evaluation by mass spectrometry of the regulation of JNK1α1. Selected reaction monitoring (SRM) analyses indicated that there are numerous post-translational modifications present on JNK1 in the absence of stress, and that hyperosmotic stress treatment did not change this state of JNK1 but rather enhanced the phosphorylation of JNK1 Ser129, Thr183, Tyr185, and Thr188. SRM also has led to the identification of a new dual phosphorylated form of JNK1α1 comprising of phospho-Tyr185 in combination with phospho-Thr188. The significance of this new form of JNK will require further evaluation in future more detailed studies, but as both residues are within the activation loop of JNK1 the possibility that this represents an alternatively regulated form of JNK1 will warrant more detailed evaluation, particularly in testing whether this dual-phospho form is also an activated form of JNK1. Finally, the application of standard mass spectrometry to the identification of proteins co-immunoprecipitating with JNK1 showed that a number of proteins involved in different processes are associated with JNK1α1. The precise roles of these new protein partners in JNK1 signaling should form the basis for future studies evaluating the diversity of JNK functions and provide further evidence supporting the complexity of actions of JNK1 in signal transduction events in the cell. This work presents the first live cell imaging and fluorescence recovery after photobleaching (FRAP) analyses for JNK, and has revealed that JNK1α1 is exchanged between and within the nucleus and the cytoplasm under basal conditions. Contrary to expectations for JNK1 as a stress-activated kinase, hyperosmotic stress treatment slows the rate of kinetics of JNK1 movement within the cell. These observations led to further evaluation by mass spectrometry of the regulation of JNK1α1. Selected reaction monitoring (SRM) analyses indicated that there are numerous post-translational modifications present on JNK1 in the absence of stress, and that hyperosmotic stress treatment did not change this state of JNK1 but rather enhanced the phosphorylation of JNK1 Ser129, Thr183, Tyr185, and Thr188. SRM also has led to the identification of a new dual phosphorylated form of JNK1α1 comprising of phospho-Tyr185 in combination with phospho-Thr188. The significance of this new form of JNK will require further evaluation in future more detailed studies, but as both residues are within the activation loop of JNK1 the possibility that this represents an alternatively regulated form of JNK1 will warrant more detailed evaluation, particularly in testing whether this dual-phospho form is also an activated form of JNK1. Finally, the application of standard mass spectrometry to the identification of proteins co-immunoprecipitating with JNK1 showed that a number of proteins involved in different processes are associated with JNK1α1. The precise roles of these new protein partners in JNK1 signaling should form the basis for future studies evaluating the diversity of JNK functions and provide further evidence supporting the complexity of actions of JNK1 in signal transduction events in the cell

Role of Oxylipins in the Inflammatory-Related Diseases NAFLD, Obesity, and Type 2 Diabetes

Oxygenated polyunsaturated fatty acids (oxylipins) are bioactive molecules established as important mediators during inflammation. Different classes of oxylipins have been found to have opposite effects, e.g., pro-inflammatory prostaglandins and anti-inflammatory resolvins. Production of the different classes of oxylipins occurs during distinct stages of development and resolution of inflammation. Chronic inflammation is involved in the progression of many pathophysiological conditions and diseases such as non-alcoholic fatty liver disease, insulin resistance, diabetes, and obesity. Determining oxylipin profiles before, during, and after inflammatory-related diseases could provide clues to the onset, development, and prevention of detrimental conditions. This review focusses on recent developments in our understanding of the role of oxylipins in inflammatory disease, and outlines novel technological advancements and approaches to study their action