Host-microbe interactions rewire metabolism in a C. elegans model of leucine breakdown deficiency.

In humans, defects in leucine catabolism cause a variety of inborn errors in metabolism. Here, we use Caenorhabditis elegans to investigate the impact of mutations in mccc-1, an enzyme that functions in leucine breakdown. Through untargeted metabolomic and transcriptomic analyses we find extensive metabolic rewiring that helps to detoxify leucine breakdown intermediates via conversion into previously undescribed metabolites and to synthesize mevalonate, an essential metabolite. We also find that the leucine breakdown product 3,3-hydroxymethylbutyrate (HMB), commonly used as a human muscle-building supplement, is toxic to C. elegans and that bacteria modulate this toxicity. Unbiased genetic screens revealed interactions between the host and microbe, where components of bacterial pyrimidine biosynthesis mitigate HMB toxicity. Finally, upregulated ketone body metabolism genes in mccc-1 mutants provide an alternative route for biosynthesis of the mevalonate precursor 3-hydroxy-3-methylglutaryl-CoA. Our work demonstrates that a complex host-bacteria interplay rewires metabolism to allow host survival when leucine catabolism is perturbed.

Antagonism between neuropeptides and monoamines in a distributed circuit for pathogen avoidance.

Pathogenic infection elicits behaviors that promote recovery and survival of the host. After exposure to the pathogenic bacterium Pseudomonas aeruginosa PA14, the nematode Caenorhabditis elegans modifies its sensory preferences to avoid the pathogen. Here, we identify antagonistic neuromodulators that shape this acquired avoidance behavior. Using an unbiased cell-directed neuropeptide screen, we show that AVK neurons upregulate and release RF/RYamide FLP-1 neuropeptides during infection to drive pathogen avoidance. Manipulations that increase or decrease AVK activity accelerate or delay pathogen avoidance, respectively, implicating AVK in the dynamics of avoidance behavior. FLP-1 neuropeptides drive pathogen avoidance through the G protein-coupled receptor DMSR-7, as well as other receptors. DMSR-7 in turn acts in multiple neurons, including tyraminergic/octopaminergic neurons that receive convergent avoidance signals from the cytokine DAF-7/transforming growth factor ß. Neuromodulators shape pathogen avoidance through multiple mechanisms and targets, in agreement with the distributed neuromodulatory connectome of C. elegans.

Pheromone-based communication influences the production of somatic extracellular vesicles in C. elegans.

Extracellular vesicles (EVs) are integral to numerous biological processes, yet it is unclear how environmental factors or interactions among individuals within a population affect EV-regulated systems. In Caenorhabditis elegans, the evolutionarily conserved large EVs, known as exophers, are part of a maternal somatic tissue resource management system. Consequently, the offspring of individuals exhibiting active exopher biogenesis (exophergenesis) develop faster. Our research focuses on unraveling the complex inter-tissue and social dynamics that govern exophergenesis. We found that ascr#10, the primary male pheromone, enhances exopher production in hermaphrodites, mediated by the G-protein-coupled receptor STR-173 in ASK sensory neurons. In contrast, pheromone produced by other hermaphrodites, ascr#3, diminishes exophergenesis within the population. This process is regulated via the neuropeptides FLP-8 and FLP-21, which originate from the URX and AQR/PQR/URX neurons, respectively. Our results reveal a regulatory network that controls the production of somatic EV by the nervous system in response to social signals.

Observation of the effect of bone marrow mesenchymal stem cell transplantation by different interventions on cirrhotic rats

Bone marrow mesenchymal stem cells (BMSCs) transplantation has attracted attention for the treatment of liver cirrhosis and end-stage liver diseases. Therefore, in this study, we evaluated the effect of different methods of BMSCs transplantation in the treatment of liver cirrhosis in rats. Seventy-two male Sprague-Dawley rats were divided into 7 groups: 10 were used to extract BMSCs, 10 were used as normal group, and the remaining 52 rats were randomly divided into five groups for testing: control group, BMSCs group, BMSCs+granulocyte colony-stimulating factor (G-CSF) group, and BMSCs+Jisheng Shenqi decoction (JSSQ) group. After the end of the intervention course, liver tissue sections of rats were subjected to hematoxylin and eosin (H&E) and Masson staining, and pathological grades were scored. Liver function [aminotransferase (ALT), aspartate aminotransferase (AST), albumin (ALB)] and hepatic fibrosis markers [hyaluronidase (HA), laminin (LN), type III procollagen (PCIII), type IV collagen (CIV)] were measured. BMSCs+JSSQ group had the best effect of reducing ALT and increasing ALB after intervention therapy (P<0.05). The reducing pathological scores and LN, PCIII, CIV of BMSCs+G-CSF group and BMSCs+JSSQ group after intervention therapy were significant, but there was no significant difference between the two groups (P>0.05). The effect of JSSQ on improving stem cell transplantation in rats with liver cirrhosis was confirmed. JSSQ combined with BMSCs could significantly improve liver function and liver pathology scores of rats with liver cirrhosis.