Biology subjects

Ayres, J. S.

Publications and source records attributed to Ayres, J. S..

9 recordsLinked to original sources

bioRxiv2026

IL-10/ACOD1 axis regulates catabolism of phagocytosed lipids in trained macrophages

Macrophages clear excess host and microbial debris to restore homeostasis in inflamed tissues, yet the regulation and molecular fate of phagocytosed lipids during innate immune training remains largely unexplored. Leveraging stable isotope tracing of 13C-labeled bacteria, we establish an experimental framework to track microbe-to-host lipid transfer and define the fates of microbial lipids in macrophages in vitro and in vivo. While naive macrophages scavenge phagocytosed bacterial fatty acids into the host lipidome, TLR4-trained macrophages direct flux to mitochondria for {beta}-oxidation or lipid droplets in the context of mitochondrial dysfunction. While TLR4 signaling increases ACOD1 expression to produce itaconate that throttles TCA flux, trained macrophages produce IL-10 that reduces ACOD1 to sustain bacterial lipid disposal and promote resolution. These findings reveal an IL-10/ACOD1 regulatory axis in trained macrophages that reprograms lipid metabolism to optimally reestablish tissue homeostasis post-inflammation.

immunology↗

bioRxiv2026

Peaceful Queen Succession in the Naked Mole Rat

The eusocial naked mole rat exhibits an extreme reproductive skew involving a single queen that monopolizes breeding through behavioral dominance. When reproductive suppression of subordinates is lifted due to removal or death of the queen, subordinate females compete to assume the reproductive role, resulting in intense aggression and intracolony wars. This aggressive reproductive strategy is thought to confer several advantages under stable environmental conditions. However, reliance on a single reproductive female has the potential to create vulnerabilities when challenged with stressors or unstable environments. Thus, in some contexts, non-violent reproductive flexibility may be beneficial. Here, we report a longitudinal study of a captive naked mole rat colony identifying an alternative, mechanistically distinct mode of queen succession in response to external stressors that impair queen reproduction without social disturbance. Elevated colony density was sufficient to impair pup survival but did not alleviate reproductive suppression or trigger aggression in the colony. By contrast, relocating the colony to a new facility caused a long-term pause in the queens reproduction, leading to the sequential emergence of her daughters as additional breeders in the absence of fighting or aggression. This resulted in a transient period of peaceful plural breeding with one daughter and ultimately resulted in another daughter assuming the primary reproductive role for the colony. Together our findings support a model in which reproductive ascension is permissive and socially tolerated when the reigning queens reproductive function is impaired, thereby expanding the mechanistic framework of naked mole rat eusociality to include peaceful, fertility-based pathways of queen succession.

animal behavior and cognition↗

bioRxiv2023

Fluoxetine promotes immunometabolic defenses to mediate host-pathogen cooperation during sepsis

Selective serotonin reuptake inhibitors (SSRIs) are some of the most prescribed drugs in the world. While they are used for their ability to increase serotonergic signaling in the brain, SSRIs are also known to have a broad range of effects beyond the brain, including immune and metabolic effects. Recent studies have demonstrated that SSRIs are protective in animal models and humans against several infections, including sepsis and COVID-19, however the mechanisms underlying this protection are largely unknown. Here we mechanistically link two previously described effects of the SSRI fluoxetine in mediating protection against sepsis. We show that fluoxetine-mediated protection is independent of peripheral serotonin, and instead increases levels of circulating IL-10. IL-10 is necessary for protection from sepsis-induced hypertriglyceridemia and cardiac triglyceride accumulation, allowing for metabolic reprogramming of the heart. Our work reveals a beneficial "off-target" effect of fluoxetine, and reveals a protective immunometabolic defense mechanism with therapeutic potential.

immunology↗

bioRxiv2023

Age-dependent roles of cardiac remodeling in sepsis defense and pathogenesis

Disease tolerance is a defense strategy essential for survival of infections, limiting physiological damage without killing the pathogen. The disease course and pathology a pathogen may cause can change over the lifespan of a host due to the structural and functional physiological changes that accumulate with age. Since successful disease tolerance responses require the host to engage mechanisms that are compatible with the disease course and pathology caused by an infection, we predicted that this defense strategy would change with age. Animals infected with a lethal dose 50 (LD50) of a pathogen often display distinct health and sickness trajectories due to differences in disease tolerance, and thus can be used to delineate tolerance mechanisms. Using a polymicrobial sepsis model, we found that despite having the same LD50, old and young susceptible mice exhibited distinct disease courses. Young survivors employed a cardioprotective mechanism via FoxO1-mediated regulation of the ubiquitin-proteosome system that was necessary for survival and protection from cardiomegaly. This same mechanism was a driver of sepsis pathogenesis in aged hosts, causing catabolic remodeling of the heart and death. Our findings have implications for the tailoring of therapy to the age of an infected individual and suggest that disease tolerance alleles may exhibit antagonistic pleiotropy.

immunology↗

bioRxiv2023

Cooperation between physiological defenses and immune resistance produces asymptomatic carriage of a lethal bacterial pathogen

Animals have evolved two defense strategies to survive infections. Antagonistic strategies include mechanisms of immune resistance that operate to sense and kill invading pathogens. Cooperative or physiological defenses mediate host adaptation to the infected state, limiting physiological damage and disease, without killing the pathogen, and have been shown to cause asymptomatic carriage and transmission of lethal pathogens. Here we demonstrate that physiological defenses cooperate with the adaptive immune response to generate long-term asymptomatic carriage of the lethal enteric murine pathogen, Citrobacter rodentium. Asymptomatic carriage of genetically virulent C. rodentium provided immune resistance against subsequent infections. Host immune protection was dependent on systemic antibody responses and pathogen virulence behavior, rather than the recognition of specific virulent factor antigens. Finally, we demonstrate that an avirulent strain of C. rodentium in the field has background mutations in two genes that are important for LPS structure. Our work reveals novel insight into how asymptomatic infections can arise mechanistically with immune resistance, mediating exclusion of phenotypically virulent enteric pathogen to promote asymptomatic carriage.

immunology↗

bioRxiv2022

CD4+ T cells regulate sickness-induced anorexia and fat wasting during a chronic parasitic infection

Catabolic responses of lean and fat energy stores are a component of the host response to infection. Cachexia is an extreme catabolic state characterized by unintentional weight loss and muscle loss, that can include fat loss. Whether cachexia plays any role in host defense or is a maladaptive consequence of host-pathogen interactions remains unknown. Traditionally studies have focused on understanding how inflammatory mediators and cells of the innate immune system contribute to the pathogenesis of cachexia and the depletion of energy stores. The cells of the adaptive immune system that regulate infection-induced cachexia remain elusive. In the present study, we examined the role of the adaptive immune response in cachexia pathogenesis using a murine model of the chronic parasitic infection Trypanosoma brucei, the causative agent of sleeping sickness. We found that the cachectic response occurs in two phases with the first stage occurring early in the infection and involved a loss of body fat mass associated with anorexia, and the second stage occurring later in the infection and involved a sustained loss of fat mass that was accompanied by lean mass wasting. CD4+ T cells were necessary for the development of the sickness-induced anorexic response during stage 1 of the infection, which led to adipose triglyceride lipase dependent lipolysis in adipocytes and the resulting fat wasting. Adipose tissue wasting had no impact on host resistance defenses or survival of infection, both of which were antibody-mediated and independent ofCD4+ T cell responses. Our work reveals a new mechanism for infection induced cachexia involving CD4+ T cell regulation of host feeding behavior and an unexpected decoupling of adaptive immune mediated resistance from the cachectic response during infection.

immunology↗

bioRxiv2021

Fat specific adipose triglyceride lipase is necessary for iron-mediated lipolysis and lipid mobilization in response to negative energy balance

Maintenance of energy balance is essential for the overall health of an organism. In mammals, both negative and positive energy balance are associated with disease states. To maintain their energy balance within a defined homeostatic setpoint, mammals have evolved complex regulatory mechanisms that control energy intake and expenditure. Traditionally, studies have focused on understanding the role of macronutrient physiology in energy balance. In the present study, we examined the role of the essential micronutrient iron in regulating energy balance. Using a dietary model, we found that a short course of excess dietary iron caused a negative energy balance resulting in a severe whole body wasting phenotype. This disruption in energy balance was due to an iron dependent increase in energy expenditure caused by a heightened basal metabolic rate and activity level. Using a transgenic mouse model lacking adipose triglyceride lipase (ATGL) specifically in fat tissue, we found that to meet the increased energetic demands, dietary iron caused increased lipid utilization that required fat specific ATGL-mediated lipid mobilization and wasting of subcutaneous white adipose tissue deposits. When fed dietary iron, mice lacking fat-specific ATGL activity were protected from fat wasting, and developed a severe cachectic response that is necessary to meet the increased energetic demands caused by the dietary regimen. Our work highlights the multi-faceted role of iron regulation of organismal metabolism and provides a novel in vivo mechanism for micronutrient control of lipolysis that is necessary for regulating mammalian energy balance.

physiology↗

bioRxiv2020

Leptin signaling regulates physiological damage and host-pathogen cooperation

To combat infections, hosts employ a combination of antagonistic and cooperative defense strategies. The former refers to pathogen killing mediated by resistance mechanisms, while the latter refers to physiological defense mechanisms that promote host health during infection independent of pathogen killing, leading to an apparent cooperation between the host and the pathogen. Previous work has shown that leptin, a pleiotropic hormone that plays a central role in regulating appetite and energy metabolism, is indispensable for resistance mechanisms, while a role for leptin signaling in cooperative host-pathogen interactions remains unknown. Using a mouse model of Yersinia pseudotuberculosis (Yptb) infection, the causative agent of Far East scarlet-like fever, we unexpectedly found that genetic inhibition of leptin signaling conferred protection from Yptb infection due to increased host-pathogen cooperation rather than greater resistance defenses. The protection against Yptb infection was not due to differences in food consumption, lipolysis or fat mass. Furthermore, we found that the survival advantage was associated with increased liver damage and dysfunction. Our work reveals an additional level of complexity for the role of leptin in infection defense and suggests that in some contexts, in addition to tolerating the pathogen, tolerating organ damage and dysfunction is more beneficial for survival than preventing the damage.

immunology↗

bioRxiv2020

Microbiota control of maternal behavior regulates early postnatal growth of offspring

Maternal-offspring bonding and maturation of maternal behavior is necessary during the early postnatal period of an infant to promote optimal development and growth. The regulation of maternal behavior is multifactorial relying both on sensory cues including auditory and olfactory signals emitted by the infant and received by the mother, as well as proper neuroendocrine responses including that of the oxytocin system. The intestinal microbiota has emerged as a critical regulator of growth and development in the early postnatal period of an individual’s life. While, this is best appreciated in the context of direct interactions between the microbiota and the infant, the microbiota can indirectly influence postnatal growth and development by regulating maternal factors. Here, we describe the identification of an intestinal E. coli strain that is pathogenic to the maternal-offspring system during the early postnatal stage of life and results in growth stunting of the offspring. However, rather than having a direct pathogenic effect on the infant, we found that this particular E. coli strain was pathogenic to the dams by interfering with the maturation of maternal behavior. The poor maternal behavior resulted in malnourishment of the pups and impaired IGF-1 signaling leading to the consequential stunted growth. Our work provides a new understanding of how the microbiota regulates postnatal growth and an additional variable that must be considered when studying the regulation of maternal behavior.Competing Interest StatementThe authors have declared no competing interest.View Full Text

physiology↗