Comparative multi-tissue profiling reveals extensive tissue-specificity in transcriptome reprogramming during thermal adaptation.

Thermal adaptation is an extensively used intervention for enhancing or suppressing thermogenic and mitochondrial activity in adipose tissues. As such, it has been suggested as a potential lifestyle intervention for body weight maintenance. While the metabolic consequences of thermal acclimation are not limited to the adipose tissues, the impact on the rest of the tissues in context of their gene expression profile remains unclear. Here, we provide a systematic characterization of the effects in a comparative multi-tissue RNA sequencing approach following exposure of mice to 10 °C, 22 °C, or 34 °C in a panel of organs consisting of spleen, bone marrow, spinal cord, brain, hypothalamus, ileum, liver, quadriceps, subcutaneous-, visceral- and brown adipose tissues. We highlight that transcriptional responses to temperature alterations exhibit a high degree of tissue-specificity both at the gene level and at GO enrichment gene sets, and show that the tissue-specificity is not directed by the distinct basic gene expression pattern exhibited by the various organs. Our study places the adaptation of individual tissues to different temperatures in a whole-organism framework and provides integrative transcriptional analysis necessary for understanding the temperature-mediated biological programming.

Humans, mice and most other mammals are constantly exposed to fluctuations in the temperature of their environment. These fluctuations cause striking metabolic effects in the body, for example, exposure to cold promotes burning of calories to generate heat, thereby reducing how much fat accumulates in the body. On the other hand, warmer temperatures strengthen the bones and protect against a bone disease known as osteoporosis. As such, it has been suggested that exposure to alternating warm or cold temperatures could be a potential lifestyle intervention that conveys various benefits to our health. Our body stores fat in tissues known as adipose tissues, which are found all over the body including under the skin and around our major organs and muscles. Exposure to cold triggers changes in the activities of some genes in the adipose tissues to burn more calories. But it remains unclear how temperature affects the activities of other organs with respect to their expression of genes in the whole-body context. Hadadi, Spiljar et al. used an RNA sequencing approach to study the activities of genes in various tissues of mice exposed to cold (10°C), room temperature (22°C), or mild warm (34°C). The experiments revealed numerous genes whose levels were different in the various organs and temperatures tested. Overall, adipose tissues experienced the biggest changes in gene levels between different temperatures, followed by tissues involved in immune responses, and the brain and spinal cord tissues. Each organ changed gene expression levels in its own way. , and this was not due to the different intimate gene expression profile between the various organs. These findings improve our understanding of how changes in temperature affect mammals by putting the responses of individual tissues into the context of the whole body. Hadadi, Spiljar et al. also generated a web-based, free-to-use application to allow others to view and further analyze the data collected in this work for gene levels in the various organs of interest.

Primary mouse osteoblast and osteoclast culturing and analysis.

Mesenchymal-derived osteoblasts play a key role in bone formation via synthesis and mineralization of the bone and bone remodeling. Osteoclasts are multinucleated cells of hematopoietic origin with a role in bone resorption. Here, we describe a protocol for generating primary cultures of these two cell types from bone tissue including the femur, tibia, and humerus of young mice. We describe methods for addressing their activity and/or differentiation, enabling studying the effects of various treatments during or following differentiation ex vivo. For further practical example of using these protocols, please refer to Chevalier et al. (2020).

Warmth Prevents Bone Loss Through the Gut Microbiota.

Osteoporosis is the most prevalent metabolic bone disease, characterized by low bone mass and microarchitectural deterioration. Here, we show that warmth exposure (34°C) protects against ovariectomy-induced bone loss by increasing trabecular bone volume, connectivity density, and thickness, leading to improved biomechanical bone strength in adult female, as well as in young male mice. Transplantation of the warm-adapted microbiota phenocopies the warmth-induced bone effects. Both warmth and warm microbiota transplantation revert the ovariectomy-induced transcriptomics changes of the tibia and increase periosteal bone formation. Combinatorial metagenomics/metabolomics analysis shows that warmth enhances bacterial polyamine biosynthesis, resulting in higher total polyamine levels in vivo. Spermine and spermidine supplementation increases bone strength, while inhibiting polyamine biosynthesis in vivo limits the beneficial warmth effects on the bone. Our data suggest warmth exposure as a potential treatment option for osteoporosis while providing a mechanistic framework for its benefits in bone disease.

Bacteriophage Prevents Alcoholic Liver Disease.

Alcoholic hepatitis is a severe alcohol-associated liver disease with minimal treatment options. A recent study by Duan et al. uncovers that the exotoxin-secreting gut bacterium Enterococcus faecalis is a critical contributor to alcoholic hepatitis. This bacterium can now be eliminated with a bacteriophage, suggesting a new way to treat this life-threatening disease.

Evaluation of colloidal platinum on cytotoxicity, oxidative stress and barrier permeability across the gut epithelium.

Colloidal platinum (Pt) is widely consumed due to its health promoting benefits. However, the exact biological effects of these nanoparticles have not been studied in detail, particularly in the gut. In the present study we observed that colloidal Pt was not cytotoxic towards three different epithelial colon cancer cell lines. Co-treatment of the colon cancer cell line Caco-2 with the oxidative stress inducing agent hydrogen peroxide (H2O2) and colloidal Pt resulted in a significant decrease in H2O2 induced oxidative stress. Colloidal Pt by itself did not induce any oxidative stress. Additionally, both overnight pretreatment of Caco-2 cells with colloidal Pt followed by 1 h treatment with H2O2, or co-treatment of cells for 1 h with colloidal Pt and H2O2 resulted in a significant recovery of cell death. Of note, the same protective effects of colloidal Pt were not observed when the oxidative stress was induced in the presence of 2, 2-azobis (2-amidinopropane) dihydrochloride, indicating that the source of free radicals may define the outcome of anti-oxidant activity of colloidal Pt. Colloidal Pt was also able to cross a model intestinal barrier formed in vitro with differentiated Caco-2 cells easily. Overall, our data indicate that colloidal Pt was not toxic towards intestinal epithelial cells, reduced H2O2 induced oxidative stress, protected from oxidative stress related death of intestinal epithelial cells and could pass a model gut barrier easily. Colloidal Pt can therefore be consumed orally for its anti-oxidant and other health promoting benefits.

Emerging cellular functions of the lipid metabolizing enzyme 15-Lipoxygenase-1.

The oxygenation of polyunsaturated fatty acids such as arachidonic and linoleic acid through lipoxygenases (LOXs) and cyclooxygenases (COXs) leads to the production of bioactive lipids that are important both in the induction of acute inflammation and its resolution. Amongst the several isoforms of LOX that are expressed in mammals, 15-LOX-1 was shown to be important both in the context of inflammation, being expressed in cells of the immune system, and in epithelial cells where the enzyme has been shown to crosstalk with a number of important signalling pathways. This review looks into the latest developments in understanding the role of 15-LOX-1 in different disease states with emphasis on the emerging role of the enzyme in the tumour microenvironment as well as a newly re-discovered form of cell death called ferroptosis. We also discuss future perspectives on the feasibility of use of this protein as a target for therapeutic interventions.

15-Lipoxygenase-1 re-expression in colorectal cancer alters endothelial cell features through enhanced expression of TSP-1 and ICAM-1.

15-lipoxygenase-1 (15-LOX-1) oxygenates linoleic acid to 13(S)-hydroxyoctadecadienoic acid (HODE). The enzyme is widely suppressed in different cancers and its re-expression has tumor suppressive effects. 15-LOX-1 has been shown to inhibit neoangiogenesis in colorectal cancer (CRC); in the present study we confirm this phenomenon and describe the mechanistic basis. We show that re-expression of 15-LOX-1 in CRC cell lines resulted in decreased transcriptional activity of HIF1α and reduced the expression and secretion of VEGF in both normoxic and hypoxic conditions. Conditioned medium (CM) was obtained from CRC or prostate cancer cell lines re-expressing 15-LOX-1 (15-LOX-1CM). 15-LOX-1CM treated aortic rings from 6-week old C57BL/6 mice showed significantly less vessel sprouting and more organized structure of vascular network. Human umbilical vein endothelial cells (HUVECs) incubated with 15-LOX-1CM showed reduced motility, enhanced expression of intercellular cell adhesion molecule (ICAM-1) and reduced tube formation but no change in proliferation or cell-cycle distribution. HUVECs incubated with 13(S)-HODE partially phenocopied the effects of 15-LOX-1CM, i.e., showed reduced motility and enhanced expression of ICAM-1, but did not reduce tube formation, implying the importance of additional factors. Therefore, a Proteome Profiler Angiogenesis Array was carried out, which showed that Thrombospondin-1 (TSP-1), a matrix glycoprotein known to strongly inhibit neovascularization, was expressed significantly more in HUVECs incubated with 15-LOX-1CM. TSP-1 blockage in HUVECs reduced the expression of ICAM-1 and enhanced cell motility, thereby providing a mechanism for reduced angiogenesis. The anti-angiogenic effects of 15-LOX-1 through enhanced expressions of ICAM-1 and TSP-1 are novel findings and should be explored further to develop therapeutic options.