Editorial: Optimizing Schools of Cytology: Discussions from the 2022 ASC/IAC Cytology Education Symposium, North American Strategies, and European Symbiosis.

This report highlights information and outcomes from the November 2022 ASC/IAC joint Cytology Education Symposium, an annual conference organized by the Cytology Programs Review Committee. The manuscript provides information on shared educational opportunities and practices for cytology students and other learners in anatomic pathology, discusses recruitment strategies for schools of cytology, conveys teaching resources, introduces perspectives on virtual microscopy and online learning, and transmits information about wellness of students in schools of cytology.

Optimizing schools of cytology: Discussions from the 2022 ASC/IAC Cytology Education Symposium, North American Strategies, and European Symbiosis.

This report highlights information and outcomes from the November 2022 ASC/IAC joint Cytology Education Symposium, an annual conference organized by the Cytology Programs Review Committee. The manuscript provides information on shared educational opportunities and practices for cytology students and other learners in anatomic pathology, discusses recruitment strategies for schools of cytology, conveys teaching resources, introduces perspectives on virtual microscopy and online learning, and transmits information about wellness of students in schools of cytology.

Hemostatic Responses to Multiple Bouts of Firefighting Activity: Female vs. Male Differences in a High Demand, High Performance Occupation.

While the fire service has long been a male-dominated occupation, women's participation in this strenuous, high risk, high performance activity has increased in recent years. Firefighting induces significant cardiovascular strain, including hemostatic disruption; however, the effect of sex on hemostatic responses has not been investigated despite evidence that there are sex-related differences in hemostatic variables at rest and following exercise. Thus, we investigated hemostatic responses in age- and BMI-matched male and female firefighters who performed 3-4 evolutions of firefighting drills over a 3 h period. Venous blood samples were collected before and after the firefighting training drills and hemostatic variables were assessed. Firefighting significantly increased platelet count and factor VIII, tissue plasminogen activator (t-PA) antigen, and t-PA activity, and decreased activated partial thromboplastin time and plasminogen activator inhibitor (PAI-1) activity. Females had lower values for epinephrine-induced platelet closure time, antithrombin III, PAI-1 activity, and PAI-1 antigen. There were no interactions between sex and time for any variables assessed. In conclusion, multiple bouts of firefighting activity resulted in a procoagulatory state. Although there were sex differences for several hemostatic variables, male and female firefighters did not differ in their hemostatic response to multiple bouts of firefighting.

HFD refeeding in mice after fasting impairs learning by activating caspase-1 in the brain.

BACKGROUND: Diets that include some aspect of fasting have dramatically increased in popularity. In addition, fasting reduces inflammasome activity in the brain while improving learning. Here, we examine the impact of refeeding a low-fat diet (LFD) or high-fat diet (HFD) after fasting. METHODS: Male wildtype (WT), caspase-1 knockout (KO) and/or IL-1 receptor 1 (IL-1R1) KO mice were fasted for 24 h or allowed ad libitum access to food (chow). Immediately after fasting, mice were allowed to refeed for 2 h in the presence of LFD, HFD or chow. Mouse learning was examined using novel object recognition (NOR) and novel location recognition (NLR). Caspase-1 activity was quantified in the brain using histochemistry (HC) and image analysis. RESULTS: Refeeding with a HFD but not a LFD or chow fully impaired both NOR and NLR. Likewise, HFD when compared to LFD refeeding increased caspase-1 activity in the whole amygdala and, particularly, in the posterior basolateral nuclei (BLp) by 2.5-fold and 4.6-fold, respectively. When caspase-1 KO or IL-1R1 KO mice were examined, learning impairment secondary to HFD refeeding did not occur. Equally, administration of n-acetylcysteine to fasted WT mice prevented HFD-dependent learning impairment and caspase-1 activation in the BLp. Finally, the free-fatty acid receptor 1 (FFAR1) antagonist, DC260126, mitigated learning impairment associated with HFD refeeding while blocking caspase-1 activation in the BLp. CONCLUSIONS: Consumption of a HFD after fasting impairs learning by a mechanism that is dependent on caspase-1 and the IL-1R1 receptor. These consequences of a HFD refeeding on the BLP of the amygdala appear linked to oxidative stress and FFAR1.

Nutritional psychoneuroimmunology: Is the inflammasome a critical convergence point for stress and nutritional dysregulation?

Psychoneuroimmunology (PNI) aims to elucidate mechanisms by which the immune system can influence behavior. Given the complexity of the brain, studies using inbred rodents have shed critical insight into the presumed vagaries of the human condition. This is particularly true for stress modeling where adverse stimuli, conditions and/or interactions elicit patterned behavioral reactions that can translate across species. As example, sickness behaviors are as easily recognized in mice as they are in humans, and a family pet. Recently, nutrition has gained prominence as a regulator of brain function. Once perceived as mostly a peripheral player, except when manifest at extremes like starvation or gluttony, nutritional and/or metabolic stress is now recognized as a worrisome contributor to poor mental health especially in those who suffer from food insecurity or overnutrition. In this review, we will explore emerging areas of rodent research that demonstrate the impact of nutritional status on the stressed brain. Our overall goal is to implicate inflammasome activation as a critical convergence point for stress and nutritional dysregulation. In doing so, we will present results from studies focused on macronutrient, micronutrient and dietary bioactives so as to encourage innovative investigation into the emerging field of nutritional PNI.

Handling stress impairs learning through a mechanism involving caspase-1 activation and adenosine signaling.

Acute stressors can induce fear and physiologic responses that prepare the body to protect from danger. A key component of this response is immune system readiness. In particular, inflammasome activation appears critical to linking stress to the immune system. Here, we show that a novel combination of handling procedures used regularly in mouse research impairs novel object recognition (NOR) and activates caspase-1 in the amygdala. In male mice, this handling-stress paradigm combined weighing, scruffing and sham abdominal injection once per hr. While one round of weigh/scruff/needle-stick had no impact on NOR, two rounds compromised NOR without impacting location memory or anxiety-like behaviors. Caspase-1 knockout (KO), IL-1 receptor 1 (IL-1R1) KO and IL-1 receptor antagonist (IL-RA)-administered mice were resistant to handling stress-induced loss of NOR. In addition, examination of the brain showed that handling stress increased caspase-1 activity 85% in the amygdala without impacting hippocampal caspase-1 activity. To delineate danger signals relevant to handling stress, caffeine-administered and adenosine 2A receptor (A2AR) KO mice were tested and found resistant to impaired learning and caspase-1 activation. Finally, mice treated with the ß-adrenergic receptor antagonist, propranolol, were resistant to handling stress-induced loss of NOR and caspase-1 activation. Taken together, these results indicate that handling stress-induced impairment of object learning is reliant on a pathway requiring A2AR-dependent activation of caspase-1 in the amygdala that appears contingent on ß-adrenergic receptor functionality.

Indoleamine 2,3-dioxygenase 1 deletion promotes Theiler's virus-induced seizures in C57BL/6J mice.

OBJECTIVE: Viral encephalitis increases the risk for developing seizures and epilepsy. Indoleamine 2,3-dioxygenase 1 (Ido1) is induced by inflammatory cytokines and functions to metabolize tryptophan to kynurenine. Kynurenine can be further metabolized to produce kynurenic acid and the N-methyl-d-aspartate receptor agonist quinolinic acid (QuinA). In the present study, we sought to determine the role of Ido1 in promoting seizures in an animal model of viral encephalitis. METHODS: C57BL/6J and Ido1 knockout mice (Ido1-KO) were infected with Theiler's murine encephalomyelitis virus (TMEV). Quantitative real-time polymerase chain reaction was used to evaluate hippocampal expression of proinflammatory cytokines, Ido1, and viral RNA. Body weights and seizure scores were recorded daily. Elevated zero maze was used to assess differences in behavior, and hippocampal pathology was determined by immunohistochemistry. RESULTS: Infected C57BL/6J mice up-regulated proinflammatory cytokines, Ido1, and genes encoding the enzymatic cascade responsible for QuinA production in the kynurenine pathway prior to the onset of seizures. Seizure incidence was elevated in Ido1-KO compared to C57BL/6J mice. Infection increased locomotor activity in Ido1-KO compared to C57BL/6J mice. Furthermore, the occurrence of seizures was associated with hyperexcitability. Neither expression of proinflammatory cytokines nor viral RNA was altered as a result of genotype. Immunohistochemical analysis revealed increased hippocampal pathology in Ido1-KO mice. SIGNIFICANCE: Our findings suggest that Ido1 deletion promotes seizures and neuropathogenesis during acute TMEV encephalitis.

Switching from a high-fat cellulose diet to a high-fat pectin diet reverses certain obesity-related morbidities.

BACKGROUND: Reducing caloric intake is a proven intervention for mitigating and modulating morbidities associated with overnutrition. Caloric restriction is difficult to affect clinically, therefore, dietary interventions that ameliorate the adverse consequences of overnutrition in the presence of a high-calorie diet would be of value. METHODS: Mice were fed an obesogenic diet containing 60% fat + 10% cellulose (HFC), or a control diet containing 10% fat + 10% cellulose (LFC) for 12 wks. Subgroups of mice were then switched from HFC to each of the following diets for an additional 5 wks: 1) 60% fat + 10% pectin (HFP), 2) LFC or 3) 10% fat + 10% pectin (LFP). To test for statistical differences, one-way or two-way ANOVAs were used with or without repeated measurements as needed. RESULTS: In comparison to HFC, HFP prevented additional weight gain while LFC and LFP triggered weight loss of 22.2 and 25.4%, respectively. Mice continued on HFC experienced a weight increase of 26% during the same 5 wk. interval. After 12 wks, HFC decreased mouse locomotion by 18% when compared to control diet, but a diet switch to LFC or LFP restored mouse movement. Importantly, HFP, LFC, and LFP reduced fasting blood glucose when compared to HFC. Likewise, HFP, LFC and LFP improved glucose tolerance and decreased fatty liver by 37.9, 49.8, 53.6 and 20.2%, 37.2, 43.7%, respectively. CONCLUSIONS: Taken together, the results indicate that the dietary fiber pectin can mitigate some adverse consequences of overnutrition even in the presence of high-fat.

Exposure to a firefighting overhaul environment without respiratory protection increases immune dysregulation and lung disease risk.

Firefighting activities appear to increase the risk of acute and chronic lung disease, including malignancy. While self-contained breathing apparatuses (SCBA) mitigate exposures to inhalable asphyxiates and carcinogens, firefighters frequently remove SCBA during overhaul when the firegrounds appear clear of visible smoke. Using a mouse model of overhaul without airway protection, the impact of fireground environment exposure on lung gene expression was assessed to identify transcripts potentially critical to firefighter-related chronic pulmonary illnesses. Lung tissue was collected 2 hrs post-overhaul and evaluated via whole genome transcriptomics by RNA-seq. Although gas metering showed that the fireground overhaul levels of carbon monoxide (CO), carbon dioxide (CO2), hydrogen cyanine (HCN), hydrogen sulfide (H2S) and oxygen (O2) were within NIOSH ceiling recommendations, 3852 lung genes were differentially expressed when mice exposed to overhaul were compared to mice on the fireground but outside the overhaul environment. Importantly, overhaul exposure was associated with an up/down-regulation of 86 genes with a fold change of 1.5 or greater (p<0.5) including the immunomodulatory-linked genes S100a8 and Tnfsf9 (downregulation) and the cancer-linked genes, Capn11 and Rorc (upregulation). Taken together these findings indicate that, without respiratory protection, exposure to the fireground overhaul environment is associated with transcriptional changes impacting proteins potentially related to inflammation-associated lung disease and cancer.

Mouse Testing Methods in Psychoneuroimmunology 2.0: Measuring Behavioral Responses.

The field of psychoneuroimmunology (PNI) aims to uncover the processes and consequences of nervous, immune, and endocrine system relationships. Behavior is a consequence of such interactions and manifests from a complex interweave of factors including immune-to-neural and neural-to-immune communication. Often the signaling molecules involved during a particular episode of neuroimmune activation are not known but behavioral response provides evidence that bioactives such as neurotransmitters and cytokines are perturbed. Immunobehavioral phenotyping is a first-line approach when examining the neuroimmune system and its reaction to immune stimulation or suppression. Behavioral response is significantly more sensitive than direct measurement of a single specific bioactive and can quickly and efficiently rule in or out relevance of a particular immune challenge or therapeutic to neuroimmunity. Classically, immunobehavioral research was focused on sickness symptoms related to bacterial infection but neuroimmune activation is now a recognized complication of diseases and disorders ranging from cancer to diabesity to Alzheimer's. Immunobehaviors include lethargy, loss of appetite, and disinterest in social activity/surrounding environment. In addition, neuroimmune activation can diminish physical activity, precipitate feelings of depression and anxiety, and impair cognitive and executive function. Provided is a detailed overview of behavioral tests frequently used to examine neuroimmune activation in mice with a special emphasis on pre-experimental conditions that can confound or prevent successful immunobehavioral experimentation.

Influenza infection triggers disease in a genetic model of experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system. Most MS patients experience periods of symptom exacerbation (relapses) followed by periods of partial recovery (remission). Interestingly, upper-respiratory viral infections increase the risk for relapse. Here, we used an autoimmune-prone T-cell receptor transgenic mouse (2D2) and a mouse-adapted human influenza virus to test the hypothesis that upper-respiratory viral infection can cause glial activation, promote immune cell trafficking to the CNS, and trigger disease. Specifically, we inoculated 2D2 mice with influenza A virus (Puerto Rico/8/34; PR8) and then monitored them for symptoms of inflammatory demyelination. Clinical and histological experimental autoimmune encephalomyelitis was observed in ∼29% of infected 2D2 mice. To further understand how peripheral infection could contribute to disease onset, we inoculated wild-type C57BL/6 mice and measured transcriptomic alterations occurring in the cerebellum and spinal cord and monitored immune cell surveillance of the CNS by flow cytometry. Infection caused temporal alterations in the transcriptome of both the cerebellum and spinal cord that was consistent with glial activation and increased T-cell, monocyte, and neutrophil trafficking to the brain at day 8 post infection. Finally, Cxcl5 expression was up-regulated in the brains of influenza-infected mice and was elevated in cerebrospinal fluid of MS patients during relapse compared with specimens acquired during remission. Collectively, these data identify a mechanism by which peripheral infection may exacerbate MS as well as other neurological diseases.

Acute fasting inhibits central caspase-1 activity reducing anxiety-like behavior and increasing novel object and object location recognition.

BACKGROUND: Inflammation within the central nervous system (CNS) is frequently comorbid with anxiety. Importantly, the pro-inflammatory cytokine most commonly associated with anxiety is IL-1ß. The bioavailability and activity of IL-1ß are regulated by caspase-1-dependent proteolysis vis-a-vis the inflammasome. Thus, interventions regulating the activation or activity of caspase-1 should reduce anxiety especially in states that foster IL-1ß maturation. METHODS: Male C57BL/6j, C57BL/6j mice treated with the capase-1 inhibitor biotin-YVAD-cmk, caspase-1 knockout (KO) mice and IL-1R1 KO mice were fasted for 24h or allowed ad libitum access to food. Immediately after fasting, caspase-1 activity was measured in brain region homogenates while activated caspase-1 was localized in the brain by immunohistochemistry. Mouse anxiety-like behavior and cognition were tested using the elevated zero maze and novel object/object location tasks, respectively. RESULTS: A 24h fast in mice reduced the activity of caspase-1 in whole brain and in the prefrontal cortex, amygdala, hippocampus, and hypothalamus by 35%, 25%, 40%, 40%, and 40% respectively. A 24h fast also reduced anxiety-like behavior by 40% and increased novel object and object location recognition by 21% and 31%, respectively. IL-1ß protein, however, was not reduced in the brain by fasting. ICV administration of YVAD decreased caspase-1 activity in the prefrontal cortex and amygdala by 55%, respectively leading to a 64% reduction in anxiety like behavior. Importantly, when caspase-1 KO or IL1-R1 KO mice are fasted, no fasting-dependent reduction in anxiety-like behavior was observed. CONCLUSIONS: Results indicate that fasting decrease anxiety-like behavior and improves memory by a mechanism tied to reducing caspase-1 activity throughout the brain.

Glial and tissue-specific regulation of Kynurenine Pathway dioxygenases by acute stress of mice.

Stressors activate the hypothalamic-pituitary-adrenal (HPA) axis and immune system eliciting changes in cognitive function, mood and anxiety. An important link between stress and altered behavior is stimulation of the Kynurenine Pathway which generates neuroactive and immunomodulatory kynurenines. Tryptophan entry into this pathway is controlled by rate-limiting indoleamine/tryptophan 2,3-dioxygenases (DOs: Ido1, Ido2, Tdo2). Although implicated as mediating changes in behavior, detecting stress-induced DO expression has proven inconsistent. Thus, C57BL/6J mice were used to characterize DO expression in brain-regions, astrocytes and microglia to characterize restraint-stress-induced DO expression. Stress increased kynurenine in brain and plasma, demonstrating increased DO activity. Of three Ido1 transcripts, only Ido1-v1 expression was increased by stress and within astrocytes, not microglia, indicating transcript- and glial-specificity. Stress increased Ido1-v1 only in frontal cortex and hypothalamus, indicating brain-region specificity. Of eight Ido2 transcripts, Ido2-v3 expression was increased by stress, again only within astrocytes. Likewise, stress increased Tdo2-FL expression in astrocytes, not microglia. Interestingly, Ido2 and Tdo2 transcripts were not correspondingly induced in Ido1-knockout (Ido1KO) mice, suggesting that Ido1 is necessary for the central DO response to acute stress. Unlike acute inflammatory models resulting in DO induction within microglia, only astrocyte DO expression was increased by acute restraint-stress, defining their unique role during stress-dependent activation of the Kynurenine Pathway.

Short-Term High-Fat Diet (HFD) Induced Anxiety-Like Behaviors and Cognitive Impairment Are Improved with Treatment by Glyburide.

Obesity-associated comorbidities such as cognitive impairment and anxiety are increasing public health burdens that have gained prevalence in children. To better understand the impact of childhood obesity on brain function, mice were fed with a high-fat diet (HFD) from weaning for 1, 3 or 6 weeks. When compared to low-fat diet (LFD)-fed mice (LFD-mice), HFD-fed mice (HFD-mice) had impaired novel object recognition (NOR) after 1 week. After 3 weeks, HFD-mice had impaired NOR and object location recognition (OLR). Additionally, these mice displayed anxiety-like behavior by measure of both the open-field and elevated zero maze (EZM) testing. At 6 weeks, HFD-mice were comparable to LFD-mice in NOR, open-field and EZM performance but they remained impaired during OLR testing. Glyburide, a second-generation sulfonylurea for the treatment of type 2 diabetes, was chosen as a countermeasure based on previous data exhibiting its potential as an anxiolytic. Interestingly, a single dose of glyburide corrected deficiencies in NOR and mitigated anxiety-like behaviors in mice fed with HFD-diet for 3-weeks. Taken together these results indicate that a HFD negatively impacts a subset of hippocampal-independent behaviors relatively rapidly, but such behaviors normalize with age. In contrast, impairment of hippocampal-sensitive memory takes longer to develop but persists. Since single-dose glyburide restores brain function in 3-week-old HFD-mice, drugs that block ATP-sensitive K(+) (KATP) channels may be of clinical relevance in the treatment of obesity-associated childhood cognitive issues and psychopathologies.

IL-4 Knock Out Mice Display Anxiety-Like Behavior.

Inflammation is a recognized antecedent and coincident factor when examining the biology of anxiety. Little is known, however, about how reductions in endogenous anti-inflammatory mediators impact anxiety. Therefore, mood- cognition- and anxiety-associated/like behaviors were examined in IL-4 knock out (KO) mice and wild-type (WT) mice. In comparison to WT mice, IL-4 KO mice demonstrated decreased burrowing and increased social exploration. No differences were seen in forced swim or saccharine preference testing. IL-4 KO mice had similar performance to WT mice in the Morris water maze and during object location and novel object recognition. In the elevated zero-maze, IL-4 KO mice, in comparison to WT mice, demonstrated anxiety-like behavior. Anxiety-like behavior in IL-4 KO mice was not observed, however, during open-field testing. Taken together, these data indicate that IL-4 KO mice display state, but not trait, anxiety suggesting that reductions in endogenous anti-inflammatory bioactives can engender subtypes of anxiety.

Modulation of neuroimmunity by adenosine and its receptors: metabolism to mental illness.

Adenosine is a pleiotropic bioactive with potent neuromodulatory properties. Due to its ability to easily cross the blood-brain barrier, it can act as a signaling molecule between the periphery and the brain. It functions through four (A1, A2A, A2B, and A3) cell surface G protein-coupled adenosine receptors (ARs) that are expressed in some combination on nearly all cells types within the CNS. By regulating the activity of adenylyl cyclase and changing the intracellular concentration of cAMP, adenosine can alter neuronal function and neurotransmission. A variety of illnesses related to metabolic dysregulation, such as type 1 diabetes and Alzheimer's disease, are associated with an elevated serum concentration of adenosine and a pathogenesis rooted in inflammation. This review describes the accepted physiologic function of adenosine in neurological disease and explores its new potential as a peripheral to central danger signal that can activate the neuroimmune system and contribute to symptoms of sickness and psychopathologies.

Effect of obesity on acute hemostatic responses to live-fire training drills.

The objective of this study was to evaluate the impact of obesity and firefighting activities on coagulation and fibrinolytic activity in relatively young, apparently healthy firefighters. Firefighters performed simulated firefighting activities for 18 minutes in a live-fire training structure. Blood samples were obtained at baseline, before firefighting, and within a few minutes of completing the activity. Nearly all markers of coagulation and fibrinolytic activity increased immediately after firefighting with an overall shift toward a procoagulatory profile. Obese firefighters exhibited lower levels of tissue plasminogen activator activity (0.98 vs 0.63 IU/ml) and higher levels of plasminogen activator inhibitor-1 activity (2.2 vs 4.5 ng/ml) at baseline compared with normal-weight firefighters, suggesting that fibrinolytic activity was lower in obese firefighters. There were few interactions between body mass index and firefighting activity, thus our findings suggest that obese firefighters did not exhibit a greater procoagulatory response to live firefighting compared with normal-weight firefighters. Acute live firefighting produced increases in both fibrinolytic and coagulatory responses; although obesity was associated with a reduced fibrinolytic profile at baseline, the changes produced by acute firefighting were similar in obese and nonobese firefighters.

The saturated fatty acid, palmitic acid, induces anxiety-like behavior in mice.

OBJECTIVES: Excess fat in the diet can impact neuropsychiatric functions by negatively affecting cognition, mood and anxiety. We sought to show that the free fatty acid (FFA), palmitic acid, can cause adverse biobehaviors in mice that last beyond an acute elevation in plasma FFAs. METHODS: Mice were administered palmitic acid or vehicle as a single intraperitoneal (IP) injection. Biobehaviors were profiled 2 and 24 h after palmitic acid treatment. Quantification of dopamine (DA), norepinephrine (NE), serotonin (5-HT) and their major metabolites was performed in cortex, hippocampus and amygdala. FFA concentration was determined in plasma. Relative fold change in mRNA expression of unfolded protein response (UPR)-associated genes was determined in brain regions. RESULTS: In a dose-dependent fashion, palmitic acid rapidly reduced mouse locomotor activity by a mechanism that did not rely on TLR4, MyD88, IL-1, IL-6 or TNFα but was dependent on fatty acid chain length. Twenty-four hours after palmitic acid administration mice exhibited anxiety-like behavior without impairment in locomotion, food intake, depressive-like behavior or spatial memory. Additionally, the serotonin metabolite 5-HIAA was increased by 33% in the amygdala 24h after palmitic acid treatment. CONCLUSIONS: Palmitic acid induces anxiety-like behavior in mice while increasing amygdala-based serotonin metabolism. These effects occur at a time point when plasma FFA levels are no longer elevated.

Fasting Induces IL-1 Resistance and Free-Fatty Acid-Mediated Up-Regulation of IL-1R2 and IL-1RA.

OBJECTIVE: Weight-loss is a near societal obsession and many diet programs use significant calorie restriction including fasting/short term starvation to generate rapid effects. Fasting is also a well-recognized cause of immunosuppression especially within the innate immune system. In this study, we sought to determine if the IL-1 arm of the neuroimmune system was down-regulated by a 24 h fast and how fasting might generate this effect. DESIGN: Mice were allowed ad libitum access to food or had food withheld for 24 h. Expression of the endogenous IL-1 antagonists, IL-1 receptor type 2 (IL-1R2), and IL-1 receptor antagonist (IL-1RA) was determined as were sickness behaviors before and after IL-1ß administration. RESULTS: Fasting markedly increased gene expression of IL-1R2 (83-fold in adipose tissue, 9.5-fold in liver) and IL-1RA (68-fold in liver). Fasted mice were protected from IL-1ß-induced weight-loss, hypoglycemia, loss of locomotor, and social anxiety. These protections were coupled to a large positive interaction of fasting and IL-1ß on IL-1R2 gene expression in adipose tissue and liver (2.6- and 1.6-fold, respectively). Fasting not only increased IL-1RA and IL-1R2 protein 2.5- and 3.2-fold, respectively, in liver but also increased IL-1R2 1.8-fold in adipose tissue. Fasting, in turn, triggered a 2.4-fold increase in plasma free-fatty acids (FFAs) and a 2.1-fold increase in plasma corticosterone. Inhibition, of glucocorticoid action with mifepristone did not impact fasting-dependent IL-1R2 or IL-1RA gene expression. Administration of the FFA, palmitate, to mice increased liver IL-1R2 and IL-1RA gene expression by 14- and 11-fold, respectively. CONCLUSION: These findings indicate that fasting augments expression of endogenous IL-1 antagonists inducing IL-1 resistance. Fasting-induced increases in plasma FFAs appears to be a signal that drives immunosuppression during fasting/short term starvation.

Adenosine through the A2A adenosine receptor increases IL-1ß in the brain contributing to anxiety.

Anxiety is one of the most commonly reported psychiatric conditions, but its pathogenesis is poorly understood. Ailments associated with activation of the innate immune system, however, are increasingly linked to anxiety disorders. In adult male mice, we found that adenosine doubled caspase-1 activity in brain by a pathway reliant on ATP-sensitive potassium (KATP) channels, protein kinase A (PKA) and the A2A adenosine receptor (AR). In addition, adenosine-dependent activation of caspase-1 increased interleukin (IL)-1ß in the brain by 2-fold. Peripheral administration of adenosine in wild-type (WT) mice led to a 2.3-fold increase in caspase-1 activity in the amygdala and to a 33% and 42% reduction in spontaneous locomotor activity and food intake, respectively, that were not observed in caspase-1 knockout (KO), IL-1 receptor type 1 (IL-1R1) KO and A2A AR KO mice or in mice administered a caspase-1 inhibitor centrally. Finally, adenosine administration increased anxiety-like behaviors in WT mice by 28% in the open field test and by 55% in the elevated zero-maze. Caspase-1 KO mice, IL-1R1 KO mice, A2A AR KO mice and WT mice treated with the KATP channel blocker, glyburide, were resistant to adenosine-induced anxiety-like behaviors. Thus, our results indicate that adenosine can act as an anxiogenic by activating caspase-1 and increasing IL-1ß in the brain.