Critical changes in hypothalamic gene networks in response to pancreatic cancer as found by single-cell RNA sequencing

OBJECTIVE: Cancer cachexia is a devastating chronic condition characterized by involuntary weight loss, muscle wasting, abnormal fat metabolism, anorexia, and fatigue. However, the molecular mechanisms underlying this syndrome remain poorly understood. In particular, the hypothalamus may play a central role in cachexia, given that it has direct access to peripheral signals because of its anatomical location and attenuated blood–brain barrier. Furthermore, this region has a critical role in regulating appetite and metabolism. METHODS: To provide a detailed analysis of the hypothalamic response to cachexia, we performed single-cell RNA-seq combined with RNA-seq of the medial basal hypothalamus (MBH) in a mouse model for pancreatic cancer. RESULTS: We found many cell type-specific changes, such as inflamed endothelial cells, stressed oligodendrocyes and both inflammatory and moderating microglia. Lcn2, a newly discovered hunger suppressing hormone, was the highest induced gene. Interestingly, cerebral treatment with LCN2 not only induced many of the observed molecular changes in cachexia but also affected gene expression in food-intake decreasing POMC neurons. In addition, we found that many of the cachexia-induced molecular changes found in the hypothalamus mimic those at the primary tumor site. CONCLUSION: Our data reveal that multiple cell types in the MBH are affected by tumor-derived factors or host factors that are induced by tumor growth, leading to a marked change in the microenvironment of neurons critical for behavioral, metabolic, and neuroendocrine outputs dysregulated during cachexia. The mechanistic insights provided in this study explain many of the clinical features of cachexia and will be useful for future therapeutic development

The Full SPECTRUM: Developing a Tripartite Partnership between Community, Government and Academia for Collaborative Social Policy Research

Problem: In Canadian society, public policies guide the development and administration of social services and systems, including the public education system, the justice system, family services, social housing and income support. However, because social services are often planned and implemented in a ‘siloed’ manner, coordination and collaboration across departments, sectors and organisations is sorely lacking. Data and resource constraints may prevent services being evaluated to ensure they meet the needs of the people for whom they are intended. When the needs of individuals are not addressed, the result is poor outcomes and wasted resources across multiple areas.Our Response: In 2018, we formed the SPECTRUM Partnership in response to a recognised need for collaborative cross-sector approaches to strengthening the policies that shape social services and systems in our country. The tripartite SPECTRUM partnership comprises representatives from community organisations, government and academia, and is an entity designed to conduct social policy research and evaluation, incorporating interdisciplinary perspectives and expertise from its members. Guided by community-driven research questions and building on existing data resources, SPECTRUM seeks to address specific knowledge gaps in social programs, services and systems. New research findings are then translated into viable public policy options, in alignment with government priorities, and presented to policy-makers for consideration.Implications: In this practice-based article, we describe the key steps we took to create the SPECTRUM partnership, build our collective capacity for research and evaluation, and transform our research findings into actionable evidence to support sound public policy. We outline four of SPECTRUM’s achievements to date in the hope that the lessons we learned during the development of the partnership may serve as a guide for others aiming to optimise public policy development in a collaborative evidence-based way

The Metagenome of an Anaerobic Microbial Community Decomposing Poplar Wood Chips

This study describes the composition and metabolic potential of a lignocellulosic biomass degrading community that decays poplar wood chips under anaerobic conditions. We examined the community that developed on poplar biomass in a non-aerated bioreactor over the course of a year, with no microbial inoculation other than the naturally occurring organisms on the woody material. The composition of this community contrasts in important ways with biomass-degrading communities associated with higher organisms, which have evolved over millions of years into a symbiotic relationship. Both mammalian and insect hosts provide partial size reduction, chemical treatments (low or high pH environments), and complex enzymatic ‘secretomes’ that improve microbial access to cell wall polymers. We hypothesized that in order to efficiently degrade coarse untreated biomass, a spontaneously assembled free-living community must both employ alternative strategies, such as enzymatic lignin depolymerization, for accessing hemicellulose and cellulose and have a much broader metabolic potential than host-associated communities. This would suggest that such a community would make a valuable resource for finding new catalytic functions involved in biomass decomposition and gaining new insight into the poorly understood process of anaerobic lignin depolymerization. Therefore, in addition to determining the major players in this community, our work specifically aimed at identifying functions potentially involved in the depolymerization of cellulose, hemicelluloses, and lignin, and to assign specific roles to the prevalent community members in the collaborative process of biomass decomposition. A bacterium similar to Magnetospirillum was identified among the dominant community members, which could play a key role in the anaerobic breakdown of aromatic compounds. We suggest that these compounds are released from the lignin fraction in poplar hardwood during the decay process, which would point to lignin-modification or depolymerization under anaerobic conditions

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Amplification and propagation of interleukin-1β signaling by murine brain endothelial and glial cells

Abstract Background During acute infections and chronic illnesses, the pro-inflammatory cytokine interleukin-1β (IL-1β) acts within the brain to elicit metabolic derangements and sickness behaviors. It is unknown which cells in the brain are the proximal targets for IL-1β with respect to the generation of these illness responses. We performed a series of in vitro experiments to (1) investigate which brain cell populations exhibit inflammatory responses to IL-1β and (2) examine the interactions between different IL-1β-responsive cell types in various co-culture combinations. Methods We treated primary cultures of murine brain microvessel endothelial cells (BMEC), astrocytes, and microglia with PBS or IL-1β, and then performed qPCR to measure inflammatory gene expression or immunocytochemistry to evaluate nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. To evaluate whether astrocytes and/or BMEC propagate inflammatory signals to microglia, we exposed microglia to astrocyte-conditioned media and co-cultured endothelial cells and glia in transwells. Treatment groups were compared by Student’s t tests or by ANOVA followed by Bonferroni-corrected t tests. Results IL-1β increased inflammatory gene expression and NF-κB activation in primary murine-mixed glia, enriched astrocyte, and BMEC cultures. Although IL-1β elicited minimal changes in inflammatory gene expression and did not induce the nuclear translocation of NF-κB in isolated microglia, these cells were more robustly activated by IL-1β when co-cultured with astrocytes and/or BMEC. We observed a polarized endothelial response to IL-1β, because the application of IL-1β to the abluminal endothelial surface produced a more complex microglial inflammatory response than that which occurred following luminal IL-1β exposure. Conclusions Inflammatory signals are detected, amplified, and propagated through the CNS via a sequential and reverberating signaling cascade involving communication between brain endothelial cells and glia. We propose that the brain’s innate immune response differs depending upon which side of the blood-brain barrier the inflammatory stimulus arises, thus allowing the brain to respond differently to central vs. peripheral inflammatory insults

Effect of 1-h moderate-intensity aerobic exercise on intramyocellular lipids in obese men before and after a lifestyle intervention

Intramyocellular lipids (IMCL) are depleted in response to an acute bout of exercise in lean endurance-trained individuals; however, it is unclear whether changes in IMCL content are also seen in response to acute and chronic exercise in obese individuals. We used magnetic resonance spectroscopy in 18 obese men and 5 normal-weight controls to assess IMCL content before and after an hour of cycling at the intensity corresponding with each participant's maximal whole-body rate of fat oxidation (Fat(max)). Fatmax was determined via indirect calorimetry during a graded exercise test on a cycle ergometer. The same outcome measures were reassessed in the obese group after a 16-week lifestyle intervention comprising dietary calorie restriction and exercise training. At baseline, IMCL content decreased in response to 1 h of cycling at Fatmax in controls (2.8 +/- 0.4 to 2.0 +/- 0.3 A.U., -39%, p = 0.02), but not in obese (5.4 +/- 2.1 vs. 5.2 +/- 2.2 A.U.,p = 0.42). The lifestyle intervention lead to weight loss (-10.0 +/- 5.4 kg, p < 0.001), improvements in maximal aerobic power (+5.2 +/- 3.4 mL/(kg.min)), maximal fat oxidation rate (+0.19 +/- 0.22 g/min), and a 29% decrease in homeostasis model assessment score (all p < 0.05). However, when the 1 h of cycling at Fatmax was repeated after the lifestyle intervention, there remained no observable change in IMCL (4.6 +/- 1.8 vs. 4.6 +/- 1.9 A.U., p = 0.92). In summary, there was no IMCL depletion in response to 1 h of cycling at moderate intensity either before or after the lifestyle intervention in obese men. An effective lifestyle intervention including moderate-intensity exercise training did not impact rate of utilisation of IMCL during acute exercise in obese men

Dexamethasone Chemotherapy Does Not Disrupt Orexin Signaling

<div><p>Background</p><p>Steroid-induced sleep disturbance is a common and highly distressing morbidity for children receiving steroid chemotherapy for the treatment of pediatric acute lymphoblastic leukemia (ALL). Sleep disturbance can negatively impact overall quality of life, neurodevelopment, memory consolidation, and wound healing. Hypothalamic orexin neurons are influential wake-promoting neurons, and disturbances in orexin signaling leads to abnormal sleep behavior. A new class of drug, the orexin receptor antagonists, could be an intriguing option for sleep disorders caused by increased orexinergic output. Our aim was to examine the impact of ALL treatment doses of corticosteroids on the orexin system in rodents and in children undergoing treatment for childhood ALL.</p><p>Methods</p><p>We administered repeated injections of dexamethasone to rodents and measured responsive orexin neural activity compared to controls. In children with newly diagnosed standard risk B-cell ALL receiving dexamethasone therapy per Children’s Oncology Group (COG) induction therapy from 2014–2016, we collected pre- and during-steroids matched CSF samples and measured the impact of steroids on CSF orexin concentration.</p><p>Results</p><p>In both rodents, all markers orexin signaling, including orexin neural output and orexin receptor expression, were preserved in the setting of dexamethasone. Additionally, we did not detect a difference in pre- and during-dexamethasone CSF orexin concentrations in children receiving dexamethasone.</p><p>Conclusions</p><p>Our results demonstrate that rodent and human orexin physiology is largely preserved in the setting of high dose dexamethasone. The data obtained in our experimental model fail to demonstrate a causative role for disruption of the orexin pathway in steroid-induced sleep disturbance.</p></div

Human CSF orexin levels.

<p>(a) Individual patient CSF orexin levels at baseline and then 8 days into dexamethasone (DEX) therapy for ALL. Mean baseline orexin concentration is equivalent to mean DEX day 8 orexin concentration. (b) There was no significant change in mean orexin level from baseline to DEX day 8 (<i>n</i> = 22). Data are expressed as mean ± SEM.</p

Mice (a, c-e, i-j) and rats (b, f-h) treated with dexamethasone (DEX) versus saline (vehicle) exhibit largely preserved orexin neuron signaling.

<p>(a) DEX does not cause a measurable difference in mouse orexin neuron gene expression as measured by RT-PCR (Vehicle <i>n</i> = 3, DEX <i>n</i> = 5). (b) DEX does not cause a measurable difference in rat orexin neuron gene expression as measured by RT-PCR (Vehicle <i>n</i> = 4, DEX <i>n</i> = 3). (c) Schematic illustrating the division between LH and PFA/DMH orexin neuron populations. (d, e) DEX does not upregulate mouse orexin neuron gene expression as measured by ISH, as grain clusters per orexin neuron (corresponding to radiolabeled <i>Hcrt</i> mRNA) are equivalent in both the DEX and NS animals in both the PFA/DMH and LH (Vehicle <i>n</i> = 9, DEX <i>n</i> = 8). (f) DEX does not alter total hypothalamic orexin (Ox-A) protein concentration in rats treated with DEX (Vehicle <i>n</i> = 7, DEX <i>n</i> = 7). (g) A disrupted normal diurnal variation of Ox-A by day 5 of DEX-treatment compared to sham (Vehicle <i>n</i> = 8, DEX <i>n</i> = 7) **<i>p</i> < 0.01. (h) On repeat testing, CSF Ox-A concentration on day 5 was equivalent between groups (Vehicle <i>n</i> = 7, DEX <i>n</i> = 7). (i, j) DEX did not cause a measurable difference in mice orexin 1 receptor gene expression (Vehicle <i>n</i> = 4, DEX <i>n</i> = 3) or orexin 2 receptor gene expression (NS <i>n</i> = 4, DEX <i>n</i> = 3) as measured by RT-PCR. Data, unless otherwise specified, represent orexin levels at the expected nadir (evening) on day 5 of DEX or sham treatment. Data are expressed as mean ± SEM.</p