Cytokine-induced sickness behavior: where do we stand?

Non-neuronal brain biology and its relevance to animal welfare

Non-neuronal cells constitute a significant portion of brain tissue and are seen as having key roles in brain homeostasis and responses to challenges. This review illustrates how non-neuronal biology can bring new perspectives to animal welfare through understanding mechanisms that determine welfare outcomes and highlighting interventions to improve welfare. Most obvious in this respect is the largely unrecognised relevance of neuroinflammation to animal welfare which is increasingly found to have roles in determining how animals respond to challenges. We start by introducing non-neuronal cells and review their involvement in affective states and cognition often seen as core psychological elements of animal welfare. We find that the evidence for a causal involvement of glia in cognition is currently more advanced than the corresponding evidence for affective states. We propose that translational research on affective disorders could usefully apply welfare science derived approaches for assessing affective states. Using evidence from translational research, we illustrate the involvement of non-neuronal cells and neuroinflammatory processes as mechanisms modulating resilience to welfare challenges including disease, pain, and social stress. We review research on impoverished environments and environmental enrichment which suggests that environmental conditions which improve animal welfare also improve resilience to challenges through balancing pro- and anti-inflammatory non-neuronal processes. We speculate that non-neuronal biology has relevance to animal welfare beyond neuro-inflammation including facilitating positive affective states. We acknowledge the relevance of neuronal biology to animal welfare whilst proposing that non-neuronal biology provides additional and relevant insights to improve animals' lives.

Hippocampal GPR35 is involved in the depression-like behaviors induced by inflammation and mediates the antidepressant effects of fluoxetine in mice

BACKGROUND

Neuroinflammation plays a pivotal role in the pathogenesis of depression. G protein-coupled receptor 35 (GPR35) is expressed in the brain and plays a role in regulating inflammatory processes. However, its specific role in depression remains unclear. Herein, we investigate the role of GPR35 in depressive behaviors induced by lipopolysaccharide (LPS) in mice.

METHODS

We employed an LPS-induced depression mouse model and conducted behavioral tests, molecular analyses, and morphological assessments, along with chemogenetic techniques, to investigate the role of GPR35 in depression.

RESULTS

Our results showed a significant increase in GPR35 expression in the brain of LPS-treated mice. Both pharmacological inhibition and genetic knockdown of GPR35 alleviated LPS-induced depressive-like behaviors by mitigating neuroinflammation, oxidative stress, synaptic plasticity deficits, and TLR4/NF-κB signaling in mice. Conversely, pharmacological activation of GPR35 notably exacerbated LPS-induced depressive-like behaviors in mice. Additionally, the GPR35 antagonist ML-145 effectively prevented LPS-induced inflammation responses in BV-2 microglia cells. Moreover, fluoxetine treatment effectively mitigated the upregulation of hippocampal GPR35 expression induced by LPS in mice. However, administration of the GPR35 agonist zaprinast reversed the antidepressant effects of fluoxetine. Chemogenetic activation of hippocampal glutamatergic neurons attenuated LPS-induced depression-like behaviors, accompanied by decreased GPR35 expression.

CONCLUSION

Hippocampal GPR35 is closely associated with depressive behaviors in the inflammatory model, highlighting its potential as a therapeutic target for antidepressant drug development.

Associations of physical activity volume and intensity with depression symptoms among US adults

Background

This study aimed to investigate the associations of physical activity (PA) volume and intensity with the risk of depression symptoms.

Methods

The data utilized in this study came from the 2011-2014 National Health and Nutrition Examination Survey. PA was measured using a triaxial accelerometer and calculated using the Monitor-Independent Movement Summary (MIMS), MIMS units are a novel metric derived from wrist-worn accelerometer data, representing the intensity of PA for each minute across the entire monitoring period. PA volume and intensity were expressed by the average of daily accumulated MIMS (Daily MIMS) and peak 30-min MIMS (Peak-30MIMS; Peak 30-min intensity), respectively. Depression symptoms were defined as Patient Health Questionnaire-9 score ≥10. Weighted logistic regression and restricted cubic splines were used to evaluate the associations between PA metrics and depression symptoms.

Results

After adjusting for all covariates, higher Daily MIMS and Peak-30MIMS were associated with lower depression risk. Each additional 1,000 units in Daily MIMS and 1-unit in Peak-30MIMS were associated with a 5% [Odds ratio (OR) = 0.95, 95% confidence interval (95% CI): 0.94, 0.98] and 2% (OR = 0.98, 95% CI: 0.97, 0.99) reduction in depression risk, respectively. When including both MIMS metrics in the same model, the association between Peak-30MIMS and depression remained significant (p = 0.02), whereas Daily MIMS did not (p = 0.60). The spline analysis indicated a monotonic decrease in the OR with higher Daily MIMS values (P for non-linear = 0.21). An initial increase followed by a decrease in OR was observed with rising Peak-30MIMS values (P for non-linear <0.01).

Conclusion

Our findings indicate that higher PA volume and intensity are associated with lower depression risk. The association between PA volume and reduced depression risk was negated after adjusting for PA intensity in US adults.

Animal Model of Autism Induced by Valproic Acid Combined with Maternal Deprivation: Sex-Specific Effects on Inflammation and Oxidative Stress

Autism spectrum disorder (ASD) etiology probably involves a complex interplay of both genetic and environmental risk factors, which includes pre- and perinatal exposure to environmental stressors. Thus, this study evaluated the effects of prenatal exposure to valproic acid (VPA) combined with maternal deprivation (MD) on behavior, oxidative stress parameters, and inflammatory state at a central and systemic level in male and female rats. Pregnant Wistar rats were exposed to VPA during gestation, and the offspring were submitted to MD. Offspring were tested for locomotor and social behavior; rats were euthanized, where the cerebellum, posterior cortex, prefrontal cortex, and peripheric blood were collected for oxidative stress and inflammatory analysis. It was observed that young rats (25-30 days old) exposed only to VPA presented a lower social approach when compared to the control group. VPA + MD rats did not present the same deficit. Female rats exposed to VPA + MD presented oxidative stress in all brain areas analyzed. Male rats in the VPA and VPA + MD groups presented oxidative stress only in the cerebellum. Regarding inflammatory parameters, male rats exposed only to MD exhibited an increase in pro-inflammatory cytokines in the blood and in the cortex total. The same was observed in females exposed only to VPA. Animals exposed to VPA + MD showed no alterations in the cytokines analyzed. In summary, gestational (VPA) and perinatal (MD) insults can affect molecular mechanisms such as oxidative stress and inflammation differently depending on the sex and brain area analyzed. Combined exposition to VPA and MD triggers oxidative stress especially in female brains without evoking an inflammatory response.

Invited review: Phenotyping strategies and genetic background of dairy cattle behavior in intensive production systems-From trait definition to genomic selection

Understanding and assessing dairy cattle behavior is critical for developing sustainable breeding programs and management practices. The behavior of individual animals can provide valuable information on their health and welfare status, improve reproductive management, and predict efficiency traits such as feed efficiency and milking efficiency. Routine genetic evaluations of animal behavior traits can contribute to optimizing breeding and management strategies for dairy cattle but require the identification of traits that capture the most important biological processes involved in behavioral responses. These traits should be heritable, repeatable, and measured in noninvasive and cost-effective ways in many individuals from the breeding populations or related reference populations. Although behavior traits are heritable in dairy cattle populations, they are highly polygenic, with no known major genes influencing their phenotypic expression. Genetically selecting dairy cattle based on their behavior can be advantageous because of their relationship with other key traits such as animal health, welfare, and productive efficiency, as well as animal and handler safety. Trait definition and longitudinal data collection are still key challenges for breeding for behavioral responses in dairy cattle. However, the more recent developments and adoption of precision technologies in dairy farms provide avenues for more objective phenotyping and genetic selection of behavior traits. Furthermore, there is still a need to standardize phenotyping protocols for existing traits and develop guidelines for recording novel behavioral traits and integrating multiple data sources. This review gives an overview of the most common indicators of dairy cattle behavior, summarizes the main methods used for analyzing animal behavior in commercial settings, describes the genetic and genomic background of previously defined behavioral traits, and discusses strategies for breeding and improving behavior traits coupled with future opportunities for genetic selection for improved behavioral responses.

Altered Function and Structure of the Cerebellum Associated with Gut-Brain Regulation in Crohn's Disease: a Structural and Functional MRI Study

This study employed structural and functional magnetic resonance imaging (MRI) to investigate changes in the function and structure of the cerebellum associated with gut-brain axis (GBA) regulation in patients diagnosed with Crohn's disease (CD). The study comprised 20 CD patients, including 12 with active disease (CD-A) and 8 in remission (CD-R), as well as 21 healthy controls. Voxel-based morphometry (VBM) was utilized for structural analysis of cerebellar gray matter volume, while independent component analysis (ICA) was applied for functional analysis of cerebellar functional connectivity (FC). The results showed significant GMV reduction in the left posterior cerebellar lobe across all CD patients compared to HCs, with more pronounced differences in the CD-A subgroup. Additionally, an increase in mean FC of the cerebellar network was observed in all CD patients, particularly in the CD-A subgroup, which demonstrated elevated FC in the vermis and bilateral posterior cerebellum. Correlation analysis revealed a positive relationship between cerebellar FC and the Crohn's Disease Activity Index (CDAI) and a trend toward a negative association with the reciprocal of the Self-rating Depression Scale (SDS) score in CD patients. The study's findings suggest that the cerebellum may play a role in the abnormal regulation of the GBA in CD patients, contributing to a better understanding of the neural mechanisms underlying CD and highlighting the cerebellum's potential role in modulating gut-brain interactions.

Projections from subfornical organ to bed nucleus of the stria terminalis modulate inflammation-induced anxiety-like behaviors in mice

Peripheral inflammation is closely related to the pathogenesis of sickness behaviors and psychiatric disorders such as anxiety and depression. The circumventricular organs (CVOs) are important brain sites to perceive peripheral inflammatory signals, but few studies have reported their role in inflammation-induced anxiety or depression. Using a mouse model of lipopolysaccharide (LPS)-induced inflammation, we identified a previously unreported role of the subfornical organ (SFO), one of the CVOs, in combating inflammation-induced anxiety. LPS treatment induced anxiety-like and sickness behaviors in mice. Although both the SFO and the organum vasculosum of the lamina terminalis (a CVO) neurons were activated after LPS treatment, only manipulating SFO neurons modulated LPS-induced anxiety-like behaviors. Activating or inhibiting SFO neurons alleviated or aggravated LPS-induced anxiety-like behaviors. In addition, SFO exerted this effect through glutamatergic projections to the bed nucleus of the stria terminalis. Manipulating SFO neurons did not affect LPS-induced sickness behaviors. Thus, we uncovered an active role of SFO neurons in counteracting peripheral inflammation-induced anxiety.

Systemic inflammation accelerates neurodegeneration in a rat model of Parkinson's disease overexpressing human alpha synuclein

Increasing efforts have been made to elucidate how genetic and environmental factors interact in Parkinson's disease (PD). In the present study, we assessed the development of symptoms on a genetic PD rat model that overexpresses human α-synuclein (Snca+/+) at a presymptomatic age, exposed to a pro-inflammatory insult by intraperitoneal injection of lipopolysaccharide (LPS), using immunohistology, high-dimensional flow cytometry, constant potential amperometry, and behavioral analyses. A single injection of LPS into WT and Snca+/+ rats triggered long-lasting increase in the activation of pro-inflammatory microglial markers, monocytes, and T lymphocytes. However, only LPS Snca+/+ rats showed dopaminergic neuronal loss in the substantia nigra pars compacta (SNpc), associated with a reduction in the release of evoked dopamine in the striatum. No significant changes were observed in the behavioral domain. We propose our double-hit animal as a reliable model to investigate the mechanisms whereby α-synuclein and inflammation interact to promote neurodegeneration in PD.

Effects of social dominance and acute social stress on morphology of microglia and structural integrity of the medial prefrontal cortex

Chronic stress increases activity of the brain's innate immune system and impairs function of the medial prefrontal cortex (mPFC). However, whether acute stress triggers similar neuroimmune mechanisms is poorly understood. Across four studies, we used a Syrian hamster model to investigate whether acute stress drives changes in mPFC microglia in a time-, subregion-, and social status-dependent manner. We found that acute social defeat increased expression of ionized calcium binding adapter molecule 1 (Iba1) in the infralimbic (IL) and prelimbic (PL) and altered the morphology Iba1+ cells 1, 2, and 7 days after social defeat. We also investigated whether acute defeat induced tissue degeneration and reductions of synaptic plasticity 2 days post-defeat. We found that while social defeat increased deposition of cellular debris and reduced synaptophysin immunoreactivity in the PL and IL, treatment with minocycline protected against these cellular changes. Finally, we tested whether a reduced conditioned defeat response in dominant compared to subordinate hamsters was associated with changes in microglia reactivity in the IL and PL. We found that while subordinate hamsters and those without an established dominance relationships showed defeat-induced changes in morphology of Iba1+ cells and cellular degeneration, dominant hamsters showed resistance to these effects of social defeat. Taken together, these findings indicate that acute social defeat alters microglial morphology, increases markers of tissue degradation, and impairs structural integrity in the IL and PL, and that experience winning competitive interactions can specifically protect the IL and reduce stress vulnerability.

A bio-behavioral model of systemic inflammation at breast cancer diagnosis and fatigue of clinical importance 2 years later

BACKGROUND

We aimed to generate a model of cancer-related fatigue (CRF) of clinical importance 2 years after diagnosis of breast cancer building on clinical and behavioral factors and integrating pre-treatment markers of systemic inflammation.

PATIENTS AND METHODS

Women with stage I-III hormone receptor-positive/human epidermal growth factor receptor 2-negative breast cancer were included from the multimodal, prospective CANTO cohort (NCT01993498). The primary outcome was global CRF of clinical importance [European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ)-C30 ≥40/100] 2 years after diagnosis (year 2). Secondary outcomes included physical, emotional, and cognitive CRF (EORTC QLQ-FA12). All pre-treatment candidate variables were assessed at diagnosis, including inflammatory markers [interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, interferon γ, IL-1 receptor antagonist, tumor necrosis factor-α, and C-reactive protein], and were tested in multivariable logistic regression models implementing multiple imputation and validation by 100-fold bootstrap resampling.

RESULTS

Among 1208 patients, 415 (34.4%) reported global CRF of clinical importance at year 2. High pre-treatment levels of IL-6 (quartile 4 versus 1) were associated with global CRF at year 2 [adjusted odds ratio (aOR): 2.06 (95% confidence interval [CI] 1.40-3.03); P = 0.0002; area under the receiver operating characteristic curve = 0.74]. Patients with high pre-treatment IL-6 had unhealthier behaviors, including being frequently either overweight or obese [62.4%; mean body mass index 28.0 (standard deviation 6.3 kg/m2)] and physically inactive (53.5% did not meet World Health Organization recommendations). Clinical and behavioral associations with CRF at year 2 included pre-treatment CRF [aOR versus no pre-treatment CRF: 3.99 (95% CI 2.81-5.66)], younger age [aOR per 1-year decrement: 1.02 (95% CI 1.01-1.03)], current tobacco smoking [aOR versus never: 1.81 (95% CI 1.26-2.58)], and worse insomnia or pain [aOR per 10-unit increment: 1.08 (95% CI 1.04-1.13), and 1.12 (95% CI 1.04-1.21), respectively]. Secondary analyses indicated additional associations of IL-2 [aOR per log-unit increment: 1.32 (95% CI 1.03-1.70)] and IL-10 [0.73 (95% CI 0.57-0.93)] with global CRF and of C-reactive protein [1.42 (95% CI 1.13-1.78)] with cognitive CRF at year 2. Emotional distress was consistently associated with physical, emotional, and cognitive CRF.

CONCLUSIONS

This study proposes a bio-behavioral framework linking pre-treatment systemic inflammation with CRF of clinical importance 2 years later among a large prospective sample of survivors of breast cancer.

Correlation of biochemical markers and inflammatory cytokines in autism spectrum disorder (ASD)

INTRODUCTION

Autism Spectrum Disorder (ASD) is a disorder that severely affects neurodevelopment, and its underlying causes are not yet entirely understood. Research suggests that there may be a connection between the occurrence of ASD and changes in immune responses. This study aims to know if some biochemical and inflammatory cytokines are promising biomarkers for ASD and whether they are involved in the pathogenesis of ASD.

METHODS

The serum levels of CRP, TNF-α, TGF-β, IL-1β, IL-10, 1 L-8, and IL-6 were measured in all of the patients (n = 22) and in the healthy (n = 12) children using ELISA method.

RESULTS

The serum concentrations of IL-10 and IL-8 were significantly lower in the ASD patients compared to the control group (p < 0.05) and there were not significant differences between CRP, TNF-α, TGF-β, IL-6 and IL-1β levels in two groups. There were positive correlations between CRP and IL-10, also CRP and IL-8, in ASD group. In contrast to the ASD patients, the correlations of IL-8, IL-10, and CRP were not significant in the control group.

CONCLUSION

In conclusion, this study highlights the potential role of certain biochemical markers and inflammatory cytokines in ASD. Specifically, the lower levels of IL-10 and IL-8 in ASD patients, along with the significant correlations between CRP and these cytokines, suggest an altered immune response in individuals with ASD. These findings support the hypothesis that immune dysregulation may be involved in ASD pathogenesis. Further research is needed to explore these biomarkers and their mechanistic links to ASD, which could lead to improved diagnostics or therapeutic strategies.

Crosstalk between peripheral inflammation and brain: Focus on the responses of microglia and astrocytes to peripheral challenge

A growing body of evidence supports the link between peripheral inflammation and impairment of neurologic functions, including mood and cognitive abilities. The pathogenic event connecting peripheral inflammation and brain dysfunction is represented by neuroinflammation, a pathogenic phenomenon that provides an important contribution to neurodegeneration and cognitive decline also in Alzheimer's, Parkinson's, Huntington's diseases, as well as in Multiple Sclerosis. It is driven by resident brain immune cells, microglia and astrocytes, that acquire an activated phenotype in response to proinflammatory molecules moving from the periphery to the brain parenchyma. Although a huge progress has been made in clarifying cellular and molecular mechanisms bridging peripheral and central inflammation, a clear picture has not been achieved so far. Therefore, experimental models are of crucial relevance to clarify knowledge gaps in this regard. Many findings demonstrate that systemic inflammation induced by pathogen-associated molecular patterns, such as lipopolysaccharide (LPS), is able to trigger neuroinflammation. Therefore, LPS-administration is widely considered a useful tool to study this phenomenon. On this basis, the present review will focus on in vivo studies based on acute and subacute effects of systemic administration of LPS, with special attention on the state of art of microglia and astrocyte response to peripheral challenge.

The role of microglia in 67NR mammary tumor-induced suppression of brain responses to immune challenges in female mice

It is poorly understood how solid peripheral tumors affect brain neuroimmune responses despite the various brain-mediated side effects and higher rates of infection reported in cancer patients. We hypothesized that chronic low-grade peripheral tumor-induced inflammation conditions microglia to drive suppression of neuroinflammatory responses to a subsequent peripheral immune challenge. Here, Balb/c murine mammary tumors attenuated the microglial inflammatory gene expression responses to lipopolysaccharide (LPS) and live Escherichia coli (E. coli) challenges and the fatigue response to an E. coli infection. In contrast, the inflammatory gene expression in response to LPS or a toll-like receptor 2 agonist of Percoll-enriched primary microglia cultures was comparable between tumor-bearing and -free mice, as were the neuroinflammatory and sickness behavioral responses to an intracerebroventricular interleukin (IL)-1β injection. These data led to the hypothesis that Balb/c mammary tumors blunt the neuroinflammatory responses to an immune challenge via a mechanism involving tumor suppression of the peripheral humoral response. Balb/c mammary tumors modestly attenuated select circulating cytokine responses to LPS and E. coli challenges. Further, a second mammary tumor/mouse strain model (E0771 tumors in C57Bl/6 mice) displayed mildly elevated inflammatory responses to an immune challenge. Taken together, these data indicate that tumor-induced suppression of neuroinflammation and sickness behaviors may be driven by a blunted microglial phenotype, partly because of an attenuated peripheral signal to the brain, which may contribute to infection responses and behavioral side effects reported in cancer patients. Finally, these neuroimmune effects likely vary based on tumor type and/or host immune phenotype.

Immune challenge affects risk sensitivity and locomotion in mosquitofish (Gambusia holbrooki)

The immune system is crucial in responding to disease-causing pathogens. However, immune responses may also cause stereotypical changes in behaviour known as sickness behaviours, which often include reduced activity. Sickness behaviours are thought to have an important role in conserving energy required to support the immune response; however, little is known about how they manifest over time or in relation to risk, particularly in fishes. Here, we induced an immune response in mosquitofish (Gambusia holbrooki) by inoculating them with Escherichia coli lipopolysaccharide (LPS). We subsequently tested batches of fish at 24 h intervals and examined: locomotory behaviour, tendency to use a refuge and fast-start response immediately following a threat stimulus (measured as peak acceleration). Control and LPS-treated fish behaved similarly on days 1, 3 and 4. However, 2 days post-inoculation, LPS fish swam more slowly and spent more time in the refuge than control fish, although no difference in post-threat peak acceleration was found. Our findings suggest that sickness behaviours peak roughly 2 days following exposure to LPS and are relatively short-lived. Specifically, immune-challenged individuals exhibit reduced locomotion and exploratory behaviour, becoming more risk averse overall while still retaining the ability to respond acutely to a threat stimulus.

Sensory sentinels: Neuroimmune detection and food allergy

Food allergy is classically characterized by an inappropriate type-2 immune response to allergenic food antigens. However, how allergens are detected and how that detection leads to the initiation of allergic immunity is poorly understood. In addition to the gastrointestinal tract, the barrier epithelium of the skin may also act as a site of food allergen sensitization. These barrier epithelia are densely innervated by sensory neurons, which respond to diverse physical environmental stimuli. Recent findings suggest that sensory neurons can directly detect a broad array of immunogens, including allergens, triggering sensory responses and the release of neuropeptides that influence immune cell function. Reciprocally, immune mediators modulate the activation or responsiveness of sensory neurons, forming neuroimmune feedback loops that may impact allergic immune responses. By utilizing cutaneous allergen exposure as a model, this review explores the pivotal role of sensory neurons in allergen detection and their dynamic bidirectional communication with the immune system, which ultimately orchestrates the type-2 immune response. Furthermore, it sheds light on how peripheral signals are integrated within the central nervous system to coordinate hallmark features of allergic reactions. Drawing from this emerging evidence, we propose that atopy arises from a dysregulated neuroimmune circuit.

Immune and neural response to acute social stress in adolescent humans and rodents

Studies in adults have linked stress-related activation of the immune system to the manifestation of psychiatric conditions. Using a translational design, this study aimed to examine the impact of social stress on immune activity in adolescents and on neuronal activity in a preclinical mouse model. Participants were 31 adolescents (ages 12-19), including 25 with mood and anxiety symptoms. Whole-blood samples were collected before and after the Trier Social Stress Test (TSST), a stress-inducing public speaking task, then cultured for 6 hours in the presence and absence of the inflammatory endotoxin lipopolysaccharide (LPS). Effects of TSST and LPS on 41 immune biomarkers were examined using repeated-measures analysis of variance. Separately, juvenile (8-week-old) male mice were non-stressed or exposed to reminder social defeat then intraperitoneally injected with saline or LPS (n = 6/group). Brains were perfused and collected for immunohistochemistry and confocal microscopy at 0, 1, 6, and 24 hours post-injection. The activity was determined by the density of cFos-positive neurons in the paraventricular hypothalamus, paraventricular thalamus, and basolateral amygdala, regions known to show sustained activation to immunological challenge. Analyses in the adolescent study indicated a strong effect of LPS but no effects of TSST or TSST×LPS interaction on immune biomarkers. Similarly, reminder social defeat did not induce sustained neuronal activity changes comparable to LPS immunological challenge in juvenile mice. Our convergent findings across species suggest that the acute immune response to stress documented in adults is not present in youth. Thus, aging and chronicity effects may play an important role in the inflammatory response to acute psychosocial stress.

Mild exogenous inflammation blunts neural signatures of bounded evidence accumulation and reward prediction error processing in healthy male participants

BACKGROUND

Altered neural haemodynamic activity during decision making and learning has been linked to the effects of inflammation on mood and motivated behaviours. So far, it has been reported that blunted mesolimbic dopamine reward signals are associated with inflammation-induced anhedonia and apathy. Nonetheless, it is still unclear whether inflammation impacts neural activity underpinning decision dynamics. The process of decision making involves integration of noisy evidence from the environment until a critical threshold of evidence is reached. There is growing empirical evidence that such process, which is usually referred to as bounded accumulation of decision evidence, is affected in the context of mental illness.

METHODS

In a randomised, placebo-controlled, crossover study, 19 healthy male participants were allocated to placebo and typhoid vaccination. Three to four hours post-injection, participants performed a probabilistic reversal-learning task during functional magnetic resonance imaging. To capture the hidden neurocognitive operations underpinning decision-making, we devised a hybrid sequential sampling and reinforcement learning computational model. We conducted whole brain analyses informed by the modelling results to investigate the effects of inflammation on the efficiency of decision dynamics and reward learning.

RESULTS

We found that during the decision phase of the task, typhoid vaccination attenuated neural signatures of bounded evidence accumulation in the dorsomedial prefrontal cortex, only for decisions requiring short integration time. Consistent with prior work, we showed that, in the outcome phase, mild acute inflammation blunted the reward prediction error in the bilateral ventral striatum and amygdala.

CONCLUSIONS

Our study extends current insights into the effects of inflammation on the neural mechanisms of decision making and shows that exogenous inflammation alters neural activity indexing efficiency of evidence integration, as a function of choice discriminability. Moreover, we replicate previous findings that inflammation blunts striatal reward prediction error signals.

Perception of unfamiliar caregivers during sickness - Using the new Caregiver Perception Task (CgPT) during experimental endotoxemia

Social withdrawal is a well-established part of sickness behavior, but in some contexts sick animals might gain from keeping close instead of keeping away. For instance, sick individuals are more willing to be near known individuals who can provide care and safety (close others) compared to when healthy. Yet, interactions with some strangers might also be beneficial (i.e., healthcare professionals), but it is not known how sickness interplay with social behavior towards such individuals. Here, we assessed if sickness affects perception of caregivers, and developed a new task, the Caregiver Perception Task (CgPT). Twenty-six participants performed the CgPT, once after an injection of lipopolysaccharide (LPS, 0.8 ng/kg body weight, n = 24), and once after an injection of saline (n = 25), one hour and forty-five minutes post-injection. During the task, participants watched short video clips of three types of caregivers: a healthcare professional taking care of a sick individual, a healthcare professional not taking care of a sick individual, and a non-healthcare professional taking care of their sick adult child or partner. After each video clip, the likability, trustworthiness, professionalism, and willingness to interact with and receive care from the caregiver were rated on visual analogue scales. Results showed that participants injected with saline rated healthcare professionals who did not take care of a sick individual less positively on all aspects compared to healthcare professionals who took care of a sick individual. Moreover, compared to saline, LPS increased the participants' willingness to receive care from healthcare professionals and non-healthcare professionals providing care, but not from healthcare professionals not providing care. Thus, our results indicate that sick individuals may approach unknown individuals with potential to provide care and support.

Longitudinal changes in brain-derived neurotrophic factor (BDNF) but not cytokines contribute to hippocampal recovery in anorexia nervosa above increases in body mass index

BACKGROUND

Physical sequelae of anorexia nervosa (AN) include a marked reduction in whole brain volume and subcortical structures such as the hippocampus. Previous research has indicated aberrant levels of inflammatory markers and growth factors in AN, which in other populations have been shown to influence hippocampal integrity.

METHODS

Here we investigated the influence of concentrations of two pro-inflammatory cytokines (tumor necrosis factor-alpha [TNF-α] and interleukin-6 [IL-6]) and brain-derived neurotrophic factor (BDNF) on the whole hippocampal volume, as well as the volumes of three regions (the hippocampal body, head, and tail) and 18 subfields bilaterally. Investigations occurred both cross-sectionally between acutely underweight adolescent/young adult females with AN (acAN; n = 82) and people recovered from AN (recAN; n = 20), each independently pairwise age-matched with healthy controls (HC), and longitudinally in acAN after partial renourishment (n = 58). Hippocampal subfield volumes were quantified using FreeSurfer. Concentrations of molecular factors were analyzed in linear models with hippocampal (subfield) volumes as the dependent variable.

RESULTS

Cross-sectionally, there was no evidence for an association between IL-6, TNF-α, or BDNF and between-group differences in hippocampal subfield volumes. Longitudinally, increasing concentrations of BDNF were positively associated with longitudinal increases in bilateral global hippocampal volumes after controlling for age, age2, estimated total intracranial volume, and increases in body mass index (BMI).

CONCLUSIONS

These findings suggest that increases in BDNF may contribute to global hippocampal recovery over and above increases in BMI during renourishment. Investigations into treatments targeted toward increasing BDNF in AN may be warranted.

Chronic inflammation: Cross linking insights from Ayurvedic Sciences, a silver lining to systems biology and personalized medicine

Precision in personalized medicine is a crucial subject that needs comprehensive discussion and scientific validation. Traditional healthcare approaches like the Ayurvedic Sciences are often contextually linked with personalized medicine. However, it is unfortunate that this knowledge concerning Ayurveda and personalized medicine is restricted to applying systems biology techniques to 'prakriti' the phenotypic expression and characterization detailed in the literature. There are other significant constructs besides prakruti that interest an Ayurvedic physician, which accounts for crafting precision in evidence-based medicinal practices. There is this influential model of Ayurvedic healthcare practice wherein the physician maps specific personalized characters in addition to prakruti to deduce the host responses to endogenous and exposome conditions. Subsequently, tailored protocols are administered that bring about holistic, personalized outcomes. The review aimed to determine the effective methods for integrating Systems Biology, Ayurvedic Sciences, and Personalized Medicine (precision medicinebased). Ayurveda adopts a holistic approach, considering multiple variables and their interconnections, while the modern reductionist approach focuses on understanding complex details of smaller parts through rigorous experimentation. Despite seeming extremes, ongoing research on lifestyle, gut health, and spiritual well-being highlights the evolving intersection between traditional Ayurvedic practices and modern science. The current focus is on developing the fundamental concept of Ayurveda Biology by incorporating Systems Biology techniques. Challenges in this integration include understanding diverse data types, bridging interdisciplinary knowledge gaps, and addressing technological limitations and ethical concerns. Overcoming these challenges will require interdisciplinary collaboration, innovative methodologies, substantial investment in technology, and cultural sensitivity to preserve Ayurveda's core principles while leveraging modern scientific advancements. The focus of discussions and debates on such collaborations should be breakthrough clinical models, such as chronic inflammation, which can be objectively related to specific stages of disease manifestations described in Ayurveda. Validating patient characteristics with systems biology approaches, particularly in shared pathologies like chronic inflammation, is crucial for bringing prediction and precision to personalized medicine.

Behavioral responses during sickness in amphibians and reptiles: Concepts, experimental design, and implications for field studies

In ectothermic vertebrates, behavioral fever, where an individual actively seeks warmer areas, seems to be a primary response to pathogens. This is considered a broad and evolutionarily conserved response among vertebrates. Recent population declines in amphibians are associated with an increase of infectious disease driven largely by climate change, habitat degradation, and pollution. Immediate action through research is required to better understand and inform conservation efforts. The literature available, does not provide unifying concepts that can guide adequate experimental protocols and interpretation of data, especially when studying animals in the field. The aim of this review is to promote common understanding of terminology and facilitating improved comprehension and application of key concepts about the occurrence of both sickness behavior or behavioral fever in ectothermic vertebrates. We start with a conceptual synthesis of sickness behavior and behavioral fever, with examples in different taxa. Through this discussion we present possible paths to standardize terminology, starting from original use in endothermic tetrapods which was expanded to ectothermic vertebrates, particularly amphibians and reptiles. This conceptual expansion from humans (endothermic vertebrates) and then to ectothermic counterparts, gravitates around the concept of 'normality'. Thus, following this discussion, we highlight caveats with experimental protocols and state the need of a reference value considered normal (RVCN), which is different from experimental control and make recommendations regarding experimental procedures and stress the value of detailed documentation of behavioral responses. We also propose some future directions that could enhance interaction among disciplines, emphasizing relationships at different levels of biological organization. This is crucial given the increasing convergence of fields such as thermal physiology, immunology, and animal behavior due to emerging diseases and other global crises impacting biodiversity.

Omics approaches open new horizons in major depressive disorder: from biomarkers to precision medicine

Major depressive disorder (MDD) is a recurrent episodic mood disorder that represents the third leading cause of disability worldwide. In MDD, several factors can simultaneously contribute to its development, which complicates its diagnosis. According to practical guidelines, antidepressants are the first-line treatment for moderate to severe major depressive episodes. Traditional treatment strategies often follow a one-size-fits-all approach, resulting in suboptimal outcomes for many patients who fail to experience a response or recovery and develop the so-called "therapy-resistant depression". The high biological and clinical inter-variability within patients and the lack of robust biomarkers hinder the finding of specific therapeutic targets, contributing to the high treatment failure rates. In this frame, precision medicine, a paradigm that tailors medical interventions to individual characteristics, would help allocate the most adequate and effective treatment for each patient while minimizing its side effects. In particular, multi-omic studies may unveil the intricate interplays between genetic predispositions and exposure to environmental factors through the study of epigenomics, transcriptomics, proteomics, metabolomics, gut microbiomics, and immunomics. The integration of the flow of multi-omic information into molecular pathways may produce better outcomes than the current psychopharmacological approach, which targets singular molecular factors mainly related to the monoamine systems, disregarding the complex network of our organism. The concept of system biomedicine involves the integration and analysis of enormous datasets generated with different technologies, creating a "patient fingerprint", which defines the underlying biological mechanisms of every patient. This review, centered on precision medicine, explores the integration of multi-omic approaches as clinical tools for prediction in MDD at a single-patient level. It investigates how combining the existing technologies used for diagnostic, stratification, prognostic, and treatment-response biomarkers discovery with artificial intelligence can improve the assessment and treatment of MDD.

Exploring Inflammation and Stress as Biological Correlates of Symptoms in Children With Advanced Cancer: A Longitudinal Feasibility Study

Background: Few studies have examined biomarkers of stress and inflammation as underlying mechanisms of symptoms in adolescents and young adults with cancer. This study determined the feasibility of collecting blood and saliva samples across time, described the range and distribution of biomarkers, and explored the association of biomarkers with symptom adverse events (AEs). Method: This longitudinal, prospective repeated-measures single-site feasibility study recruited N  =  10 children (M = 12.5 years) receiving treatment for advanced cancer. Symptom AE data and inflammation (cytokines and C-reactive protein) and physiologic response to stress (salivary cortisol and salivary alpha-amylase) biomarker levels were collected at three time points. Descriptive statistics were used to examine feasibility and acceptability and to summarize symptom AE, stress, and inflammatory biomarker data. A linear regression model was used to determine cortisol diurnal slopes. The relationship between symptom and inflammatory biomarker data was explored and Hedges's g statistic was used to determine its effect size. Results: Participants provided 83% of saliva samples (n  =  199/240) and 185 samples were sufficient to be analyzed. Nurses collected 97% (n  =  29/30) of blood samples. Participants reported the saliva collection instructions, kits, and reminders were clear and helpful. Insomnia, pain, fatigue, and anxiety demonstrated the most medium and large negative effects with inflammatory markers. Symptom AEs demonstrated the highest number of medium and large negative effects with interleukin-8 and tumor necrosis factor-alpha (-0.53 to -2.00). Discussion: The results indicate longitudinal concurrent collection of symptom and biomarker data is feasible and inflammatory and stress biomarkers merit consideration for inclusion in future studies.

Perceived Control and Inflammation: Mediating and Moderating Effects in the Relationship Between Cumulative Trauma and Depression

OBJECTIVE

The effects of trauma exposure on depression risk and severity are well established, but psychosocial and biological factors that impact or explain those relationships remain poorly understood. This study examined the moderating and mediating effects of perceived control and inflammation in the relationship between trauma and depression.

METHODS

Moderation analyses and longitudinal mediation analyses were conducted on data from 945 adults who completed all three waves (spanning around 19 years) of the Midlife Development in the United States (MIDUS) study and the MIDUS Biomarker Study. Data were collected during a phone interview, self-report surveys distributed in the mail, and an in-person blood draw. Two dimensions of perceived control-mastery and constraints-were examined separately in all analyses.

RESULTS

Perceived control did not significantly moderate the relationship between trauma and depression severity at MIDUS 2 ( b = 0.03, SE = .02, p = .091). Constraints significantly mediated the relationship between trauma and MIDUS 3 depression (indirect effect = 0.03, SE = 0.01, p = .016) but not after accounting for MIDUS 2 depression. Perceived control did not have a significant moderating effect in the relationships between trauma and inflammation or inflammation and depression.

CONCLUSIONS

Findings from this study revealed that perceived control may be better characterized as an explanatory factor rather than a buffer in trauma-associated depression. Perceived constraints in particular may be a useful treatment target for trauma-associated depression. Further research is needed to examine whether these results generalize to populations other than among mostly non-Hispanic White adults in the United States.

Unique pathways downstream of TLR-4 and TLR-7 activation: sex-dependent behavioural, cytokine, and metabolic consequences

Introduction

Post-infection syndromes are characterised by fatigue, muscle pain, anhedonia, and cognitive impairment; mechanistic studies exploring these syndromes have focussed on pathways downstream of Toll-like receptor (TLR) 4 activation. Here, we investigated the mechanistic interplay between behaviour, metabolism, and inflammation downstream of TLR-7 activation compared to TLR-4 activation in male and female CD1 mice.

Methods

Animals received either a TLR-4 (LPS; 0.83 mg/kg) or TLR-7 (R848, 5 mg/kg) agonist, or saline, and behaviour was analysed in an Open Field (OF) at 24 h (n = 20/group). Plasma, liver, and prefrontal cortex (PFC) were collected for gene expression analysis at 24 h and 1H-NMR metabolomics.

Results

TLR-4 and TLR-7 activation decreased distance travelled and rearing in the OF, but activation of each receptor induced distinct cytokine responses and metabolome profiles. LPS increased IL-1β expression and CXCL1 in the PFC, but TLR7 activation did not and strongly induced PFC CXCL10 expression. Thus, TLR7 induced sickness behaviour is independent of IL-1β expression. In both cases, the behavioural response to TLR activation was sexually dimorphic: females were more resilient. However, dissociation was observed between the resilient female mice behaviour and the levels of gene cytokine expression, which was, in general, higher in the female mice. However, the metabolic shifts induced by immune activation were better correlated with the sex-dependent behavioural dimorphisms; increased levels of antioxidant potential in the female brain are intrinsic male/female metabolome differences. A common feature of both TLR4 and TLR7 activation was an increase in N-acetyl aspartate (NAA) in the PFC, which is likely be an allostatic response to the challenges as sickness behaviour is inversely correlated with NAA levels.

Discussion

The results highlight how the cytokine profile induced by one PAMP cannot be extrapolated to another, but they do reveal how the manipulation of the conserved metabolome response might afford a more generic approach to the treatment of post-infection syndromes.

Exploring the role of inflammation in major depressive disorder: beyond the monoamine hypothesis

Major depressive disorder affects approximately 8.4% of the United States population. The World Health Organization estimates that 280 million adults worldwide are suffering from depression. They have estimated that by 2030 it will be the second most serious condition. Current treatment relies on the monoamine hypothesis, however, one-third of patients with MDD do not respond to monoamine-based antidepressants. For years, it was hypothesized that the primary pathway of MDD involved serotonin as the main neurotransmitter. The monoamine hypothesis, a widely accepted theory, sought to explain the biological basis of MDD as being caused by the depletion of monoamine neurotransmitters, namely norepinephrine and serotonin. This hypothesis regarding monoamines as the pathophysiological basis of MDD led to the design and widespread use of selective serotonin reuptake inhibitors. However, given that only one-third of patients improve with SSRI it is reasonable to infer that the pathway involved is more complex than once hypothesized and there are more neurotransmitters, receptors, and molecules involved. The monoamine hypothesis does not explain why there is a delay in the onset of effect and action of SSRIs. Several studies have demonstrated that chronic stress is a risk factor for the development of MDD. Thus the monoamine hypothesis alone is not enough to fully account for the pathophysiology of MDD highlighting the need for further research involving the pathways of MDD. In this paper, we review the role of inflammation and cytokines on MDD and discuss other pathways involved in the development and persistence of depressive symptoms.

Mechanistic insights into the anti-depressant effect of curcumin based on network pharmacology and experimental validation

Curcumin (CUR) exhibits a definite curative effect in the treatment of depression. To identify potential antidepressant targets and mechanisms of action of CUR. This study used network pharmacology to explore the signaling pathways and CUR-related targets in depression. C57BL/6 J mice (male,12-14 weeks old) were randomly divided into four groups (n = 8): saline-treated (control mice), lipopolysaccharide (LPS, 2 mg/kg/day, intraperitoneally), LPS + CUR (50 mg/kg/day, intragastrically), and LPS + CUR + LY294002 (7.5 mg/kg/day, intraperitoneally). After 1 week, behavioral tests were performed. Then, neuronal damage in the prefrontal cortex of mice was evaluated by hematoxylin-eosin (HE) staining. We uncovered the main active mechanism of CUR against depression using Western blotting and enzyme-linked immunosorbent assay (ELISA). Gene set enrichment analysis (GSEA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways showed that the most significantly enriched pathway in CUR against depression was the PI3K-Akt pathway. Moreover, 52 targets were significantly correlated with the PI3K-Akt signaling pathway and CUR-related targets. In addition, among the top 50 targets ranked by degree in the protein-protein interaction (PPI) network, there were 23 targets involved in the 52 intersection targets. Administration of LPS alone extended immobility time in the open field test (OFT) and tail suspension test (TST) and decreased sucrose consumption in the sucrose preference test (SPT). Pretreatment with CUR relieved LPS-induced changes in the behavioral tests, activity of the PI3K-Akt signaling pathway, neuronal damage in the prefrontal cortex (PFC), and inflammatory response. Moreover, inhibition of the PI3K-Akt signaling pathway by LY294002 blocked the therapeutic effects of CUR. Our study indicates that CUR may be an effective antidepressant agent in an LPS-induced mouse model, partly because of its anti-inflammatory action through the PI3K-Akt signaling pathway.

Neurodevelopmental and Neuropsychiatric Disorders

This chapter will focus on microglial involvement in neurodevelopmental and neuropsychiatric disorders, particularly autism spectrum disorder (ASD), schizophrenia and major depressive disorder (MDD). We will describe the neuroimmune risk factors that contribute to the etiopathology of these disorders across the lifespan, including both in early life and adulthood. Microglia, being the resident immune cells of the central nervous system, could play a key role in triggering and determining the outcome of these disorders. This chapter will review preclinical and clinical findings where microglial morphology and function were examined in the contexts of ASD, schizophrenia and MDD. Clinical evidence points out to altered microglial morphology and reactivity, as well as increased expression of pro-inflammatory cytokines, supporting the idea that microglial abnormalities are involved in these disorders. Indeed, animal models for these disorders found altered microglial morphology and homeostatic functions which resulted in behaviours related to these disorders. Additionally, as microglia have emerged as promising therapeutic targets, we will also address in this chapter therapies involving microglial mechanisms for the treatment of neurodevelopmental and neuropsychiatric disorders.

Defensive responses: behaviour, the brain and the body

Most animals live under constant threat from predators, and predation has been a major selective force in shaping animal behaviour. Nevertheless, defence responses against predatory threats need to be balanced against other adaptive behaviours such as foraging, mating and recovering from infection. This behavioural balance in ethologically relevant contexts requires adequate integration of internal and external signals in a complex interplay between the brain and the body. Despite this complexity, research has often considered defensive behaviour as entirely mediated by the brain processing threat-related information obtained via perception of the external environment. However, accumulating evidence suggests that the endocrine, immune, gastrointestinal and reproductive systems have important roles in modulating behavioural responses to threat. In this Review, we focus on how predatory threat defence responses are shaped by threat imminence and review the circuitry between subcortical brain regions involved in mediating defensive behaviours. Then, we discuss the intersection of peripheral systems involved in internal states related to infection, hunger and mating with the neurocircuits that underlie defence responses against predatory threat. Through this process, we aim to elucidate the interconnections between the brain and body as an integrated network that facilitates appropriate defensive responses to threat and to discuss the implications for future behavioural research.

Advance in Neurotoxicity Research from Development to Aging

A substance capable of inducing a consistent pattern of neural dysfunction in the chemistry or structure of the nervous system may be defined as neurotoxic [...].

Does depression in mid-life predispose to greater cognitive decline in later life in the Whitehall II cohort?

BACKGROUND

Later-life depression appears to have different symptomatology and possibly underlying pathology to younger adults. Depression is linked to dementia but whether it is a risk factor or an early sign of dementia remains unclear. Neuroinflammation is increasingly recognised in both conditions.

AIMS

To investigate the link between depression, inflammation and dementia. We hypothesised that recurrent depression increases the rate of cognitive decline in older adults and that this effect is modified by anti-inflammatory medication.

METHODS

We used data from Whitehall II including cognitive test results and reliable measures to assess depression. Depression was defined as a self-reported diagnosis or a score of ≥20 on the CESD. The presence/absence of inflammatory illness was assessed using a standardised list of inflammatory conditions. Individuals with dementia, chronic neurological and psychotic conditions were excluded. Logistic and linear regression was used to examine the effect of depression on cognitive test performance and the effect of chronic inflammation.

LIMITATIONS

Lack of clinical diagnoses of depression.

RESULTS

There were 1063 individuals with and 2572 without depression. Depression did not affect deterioration in episodic memory, verbal fluency or the AH4 test at 15-year follow up. We found no evidence of an effect of anti-inflammatory medication. Depressed individuals had worse cross-sectional performance on the Mill Hill test and tests of abstract reasoning and verbal fluency at both baseline and 15-year follow-up.

CONCLUSIONS

Using a UK based study with a long follow-up interval we have shown that depression in individuals aged >50 is not associated with increased cognitive decline.

The contributions of parental lactation on offspring development: It's not udder nonsense!

The Developmental Origins of Health and Disease (DOHaD) hypothesis describes how maternal stress exposures experienced during critical periods of perinatal life are linked to altered developmental trajectories in offspring. Perinatal stress also induces changes in lactogenesis, milk volume, maternal care, and the nutritive and non-nutritive components of milk, affecting short and long-term developmental outcomes in offspring. For instance, selective early life stressors shape the contents of milk, including macro/micronutrients, immune components, microbiota, enzymes, hormones, milk-derived extracellular vesicles, and milk microRNAs. In this review, we highlight the contributions of parental lactation to offspring development by examining changes in the composition of breast milk in response to three well-characterized maternal stressors: nutritive stress, immune stress, and psychological stress. We discuss recent findings in human, animal, and in vitro models, their clinical relevance, study limitations, and potential therapeutic significance to improving human health and infant survival. We also discuss the benefits of enrichment methods and support tools that can be used to improve milk quality and volume as well as related developmental outcomes in offspring. Lastly, we use evidence-based primary literature to convey that even though select maternal stressors may modulate lactation biology (by influencing milk composition) depending on the severity and length of exposure, exclusive and/or prolonged milk feeding may attenuate the negative in utero effects of early life stressors and promote healthy developmental trajectories. Overall, scientific evidence supports lactation to be protective against nutritive and immune stressors, but the benefits of lactation in response to psychological stressors need further investigation.

Inflammation-induced reorientation of reward versus punishment sensitivity is attenuated by minocycline

BACKGROUND

Inflammation rapidly reorients motivational state, mood is impaired, pleasurable activities avoided and sensitivity to negative stimuli enhanced. When sustained, this can precipitate major depressive episodes. In humans, this has been linked to opposing actions of inflammation on striatal/insula reward/punishment learning signals while in rodents, motivational impairments can be attenuated with minocycline, implicating a mechanistic role for microglia. Here we investigated whether minocycline also inhibits the reorienting effects of lipopolysaccharide (LPS) on reward/punishment sensitivity in humans. Methods Using a crossover design, fifteen healthy volunteers underwent two experimental sessions in which they each received LPS (1 ng/kg) and placebo. Half (N = 8) received minocycline (100 mg bd) and half (N = 7) an identical looking placebo for 3½ days before each session. Six hours post-injection participants completed a probabilistic instrumental learning task in which they had to learn to select high probability reward (win £1) and avoid high probability punishment (lose £1) stimuli to maximise their gains and minimize losses. Physiological and sickness responses were sampled hourly and blood sampled at baseline, 3 and 6 h post-injection. Results LPS induced robust peripheral physiological: temperature, heart rate and immune: differential white cell, IL-6, TNF-α, IL-8, IL-10 responses (all condition × time interactions: p < 0.005), none were significantly modulated by minocycline (p > 0.1). LPS also biased behavior, enhancing punishment compared with reward sensitivity (F(1,13) = 6.10, p = 0.028). Minocycline significantly attenuated this inflammation-induced shift in reward versus punishment sensitivity (F(1,13) = 4.28, p = 0.033). Conclusions These data replicate the previous finding that systemic inflammation rapidly impairs sensitivity to rewards versus punishments in humans and extend this by implicating activated microglia in this acute motivational reorientation with implications for the development of microglial-targeted immune-modulatory therapies in depression.

Evolutionary psychiatry: foundations, progress and challenges

Evolutionary biology provides a crucial foundation for medicine and behavioral science that has been missing from psychiatry. Its absence helps to explain slow progress; its advent promises major advances. Instead of offering a new kind of treatment, evolutionary psychiatry provides a scientific foundation useful for all kinds of treatment. It expands the search for causes from mechanistic explanations for disease in some individuals to evolutionary explanations for traits that make all members of a species vulnerable to disease. For instance, capacities for symptoms such as pain, cough, anxiety and low mood are universal because they are useful in certain situations. Failing to recognize the utility of anxiety and low mood is at the root of many problems in psychiatry. Determining if an emotion is normal and if it is useful requires understanding an individual's life situation. Conducting a review of social systems, parallel to the review of systems in the rest of medicine, can help achieve that understanding. Coping with substance abuse is advanced by acknowledging how substances available in modern environments hijack chemically mediated learning mechanisms. Understanding why eating spirals out of control in modern environments is aided by recognizing the motivations for caloric restriction and how it arouses famine protection mechanisms that induce binge eating. Finally, explaining the persistence of alleles that cause serious mental disorders requires evolutionary explanations of why some systems are intrinsically vulnerable to failure. The thrill of finding functions for apparent diseases is evolutionary psychiatry's greatest strength and weakness. Recognizing bad feelings as evolved adaptations corrects psychiatry's pervasive mistake of viewing all symptoms as if they were disease manifestations. However, viewing diseases such as panic disorder, melancholia and schizophrenia as if they are adaptations is an equally serious mistake in evolutionary psychiatry. Progress will come from framing and testing specific hypotheses about why natural selection left us vulnerable to mental disorders. The efforts of many people over many years will be needed before we will know if evolutionary biology can provide a new paradigm for understanding and treating mental disorders.

Fatigue during acute systemic inflammation is associated with reduced mental effort expenditure while task accuracy is preserved

BACKGROUND

Earlier work within the physical domain showed that acute inflammation changes motivational prioritization and effort allocation rather than physical abilities. It is currently unclear whether a similar motivational framework accounts for the mental fatigue and cognitive symptoms of acute sickness. Accordingly, this study aimed to assess the relationship between fatigue, cytokines and mental effort-based decision making during acute systemic inflammation.

METHODS

Eighty-five participants (41 males; 18-30 years (M=23.0, SD=2.4)) performed a mental effort-based decision-making task before, 2 hours after, and 5 hours after intravenous administration of 1 ng/kg bacterial lipopolysaccharide (LPS) to induce systemic inflammation. Plasma concentrations of cytokines (interleukin (IL)-6, IL-8 and tumor necrosis factor (TNF)) and fatigue levels were assessed at similar timepoints. In the task, participants decided whether they wanted to perform (i.e., 'accepted') arithmetic calculations of varying difficulty (3 levels: easy, medium, hard) in order to obtain rewards (3 levels: 5, 6 or 7 points). Acceptance rates were analyzed using a binomial generalized estimated equation (GEE) approach with effort, reward and time as independent variables. Arithmetic performance was measured per effort level prior to the decisions and included as a covariate. Associations between acceptance rates, fatigue (self-reported) and cytokine concentrations levels were analyzed using partial correlation analyses.

RESULTS

Plasma cytokine concentrations and fatigue were increased at 2 hours post-LPS compared to baseline and 5 hours post-LPS administration. Acceptance rates decreased for medium, but not for easy or hard effort levels at 2 hours post-LPS versus baseline and 5 hours post-LPS administration, irrespective of reward level. This reduction in acceptance rates occurred despite improved accuracy on the arithmetic calculations itself. Reduced acceptance rates for medium effort were associated with increased fatigue, but not with increased cytokines.

CONCLUSION

Fatigue during acute systemic inflammation is associated with alterations in mental effort allocation, similarly as observed previously for physical effort-based choice. Specifically, willingness to exert mental effort depended on effort and not reward information, while task accuracy was preserved. These results extend the motivational account of inflammation to the mental domain and suggest that inflammation may not necessarily affect domain-specific mental abilities, but rather affects domain-general effort-allocation processes.

A review of cytokine-based pathophysiology of Long COVID symptoms

The Long COVID/Post Acute Sequelae of COVID-19 (PASC) group includes patients with initial mild-to-moderate symptoms during the acute phase of the illness, in whom recovery is prolonged, or new symptoms are developed over months. Here, we propose a description of the pathophysiology of the Long COVID presentation based on inflammatory cytokine cascades and the p38 MAP kinase signaling pathways that regulate cytokine production. In this model, the SARS-CoV-2 viral infection is hypothesized to trigger a dysregulated peripheral immune system activation with subsequent cytokine release. Chronic low-grade inflammation leads to dysregulated brain microglia with an exaggerated release of central cytokines, producing neuroinflammation. Immunothrombosis linked to chronic inflammation with microclot formation leads to decreased tissue perfusion and ischemia. Intermittent fatigue, Post Exertional Malaise (PEM), CNS symptoms with "brain fog," arthralgias, paresthesias, dysautonomia, and GI and ophthalmic problems can consequently arise as result of the elevated peripheral and central cytokines. There are abundant similarities between symptoms in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). DNA polymorphisms and viral-induced epigenetic changes to cytokine gene expression may lead to chronic inflammation in Long COVID patients, predisposing some to develop autoimmunity, which may be the gateway to ME/CFS.

Environmental Enrichment Protects against Neurotoxic Effects of Lipopolysaccharide: A Comprehensive Overview

Neuroinflammation is a pathophysiological condition associated with damage to the nervous system. Maternal immune activation and early immune activation have adverse effects on the development of the nervous system and cognitive functions. Neuroinflammation during adulthood leads to neurodegenerative diseases. Lipopolysaccharide (LPS) is used in preclinical research to mimic neurotoxic effects leading to systemic inflammation. Environmental enrichment (EE) has been reported to cause a wide range of beneficial changes in the brain. Based on the above, the purpose of the present review is to describe the effects of exposure to EE paradigms in counteracting LPS-induced neuroinflammation throughout the lifespan. Up to October 2022, a methodical search of studies in the literature, using the PubMed and Scopus databases, was performed, focusing on exposure to LPS, as an inflammatory mediator, and to EE paradigms in preclinical murine models. On the basis of the inclusion criteria, 22 articles were considered and analyzed in the present review. EE exerts sex- and age-dependent neuroprotective and therapeutic effects in animals exposed to the neurotoxic action of LPS. EE’s beneficial effects are present throughout the various ages of life. A healthy lifestyle and stimulating environments are essential to counteract the damages induced by neurotoxic exposure to LPS.

The social environment alters neural responses to a lipopolysaccharide challenge

Sick animals display drastic changes in their behavioral patterns, including decreased activity, decreased food and water intake, and decreased interest in social interactions. These behaviors, collectively called "sickness behaviors", can be socially modulated. For example, when provided with mating opportunities, males of several species show reduced sickness behaviors. While the behavior is known to change, how the social environment affects neural molecular responses to sickness is not known. Here, we used a species, the zebra finch, Taeniopygia guttata, where males have been shown to decrease sickness behaviors when presented with novel females. Using this paradigm, we obtained samples from three brain regions (the hypothalamus, the bed nucleus of the stria terminalis, and the nucleus taeniae) from lipopolysaccharide (LPS) or control treated males housed under four different social environments. Manipulation of the social environment rapidly changed the strength and co-expression patterns of the neural molecular responses to the immune challenge in all brain regions tested, therefore suggesting that the social environment plays a significant role in determining the neural responses to an infection. In particular, brains of males paired with a novel female showed muted immune responses to LPS, as well as altered synaptic signaling. Neural metabolic activity in response to the LPS challenge was also affected by the social environment. Our results provide new insights into the effects of the social environment on brain responses to an infection, thereby improving our understanding of how the social environment can affect health.

Social Safety Theory: Conceptual foundation, underlying mechanisms, and future directions

Classic theories of stress and health are largely based on assumptions regarding how different psychosocial stressors influence biological processes that, in turn, affect human health and behavior. Although theoretically rich, this work has yielded little consensus and led to numerous conceptual, measurement, and reproducibility issues. Social Safety Theory aims to address these issues by using the primary goal and regulatory logic of the human brain and immune system as the basis for specifying the social-environmental situations to which these systems should respond most strongly to maximize reproductive success and survival. This analysis gave rise to the integrated, multi-level formulation described herein, which transforms thinking about stress biology and provides a biologically based, evolutionary account for how and why experiences of social safety and social threat are strongly related to health, well-being, aging, and longevity. In doing so, the theory advances a testable framework for investigating the biopsychosocial roots of health disparities as well as how health-relevant biopsychosocial processes crystalize over time and how perceptions of the social environment interact with childhood microbial environment, birth cohort, culture, air pollution, genetics, sleep, diet, personality, and self-harm to affect health. The theory also highlights several interventions for reducing social threat and promoting resilience.

LPS Triggers Acute Neuroinflammation and Parkinsonism Involving NLRP3 Inflammasome Pathway and Mitochondrial CI Dysfunction in the Rat

Whether neuroinflammation leads to dopaminergic nigrostriatal system neurodegeneration is controversial. We addressed this issue by inducing acute neuroinflammation in the substantia nigra (SN) with a single local administration (5 µg/2 µL saline solution) of lipopolysaccharide (LPS). Neuroinflammatory variables were assessed from 48 h to 30 days after the injury by immunostaining for activated microglia (Iba-1 +), neurotoxic A1 astrocytes (C3 + and GFAP +), and active caspase-1. We also evaluated NLRP3 activation and Il-1β levels by western blot and mitochondrial complex I (CI) activity. Fever and sickness behavior was assessed for 24 h, and motor behavior deficits were followed up until day 30. On this day, we evaluated the cellular senescence marker β-galactosidase (β-Gal) in the SN and tyrosine hydroxylase (TH) in the SN and striatum. After LPS injection, Iba-1 (+), C3 (+), and S100A10 (+) cells were maximally present at 48 h and reached basal levels on day 30. NLRP3 activation occurred at 24 h and was followed by a rise of active caspase-1 (+), Il-1β, and decreased mitochondrial CI activity until 48 h. A significant loss of nigral TH (+) cells and striatal terminals was associated with motor deficits on day 30. The remaining TH (+) cells were β-Gal (+), suggesting senescent dopaminergic neurons. All the histopathological changes also appeared on the contralateral side. Our results show that unilaterally LPS-induced neuroinflammation can cause bilateral neurodegeneration of the nigrostriatal dopaminergic system and are relevant for understanding Parkinson's disease (PD) neuropathology.

Blocking osteopontin expression attenuates neuroinflammation and mitigates LPS-induced depressive-like behavior in mice

INTRODUCTION

Neuroinflammation plays an important role in the development of major depressive disorder (MDD). Osteopontin (OPN) is one of the key molecules involved in neuroinflammation. We demonstrate here for the first time a key role of OPN in lipopolysaccharide (LPS)-induced depressive-like behavioral syndrome.

METHODS

Systemic administration of LPS (5 mg/kg) mimics distinct depressive-like behavior, which could significantly upregulate OPN expression in microglia/macrophage in the hippocampus. The neurobehavioral assessments, quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), Western blot, immunofluorescent staining, flow cytometry cell staining and Golgi staining were performed.

RESULTS

Similar to fluoxetine treatment (the positive control), OPN knockdown with shRNA lentivirus markedly reversed LPS-induced depressive-like behavior. Moreover, knockdown of OPN suppressed LPS-induced proinflammatory cytokine expression, microglial activation, dendritic spines loss, as well as unregulated PSD-95 and BDNF in the hippocampus.

CONCLUSION

We demonstrated that targeting OPN expression in microglia/macrophage might help to rescue LPS-induced depressive-like behavior. The underlying mechanism may relate to the modulation of neuroinflammation, BDNF signaling and synaptic structural complexity.

Gut microbiota mediated inflammation, neuroendocrine and neurotrophic functions involved in the antidepressant-like effects of diosgenin in chronic restraint stress

BACKGROUND

Diosgenin is a well-known steroid saponin possessing neuroprotective activities. However, it is unknown whether diosgenin could alleviate depression-like symptoms.

METHODS

The antidepressant-like effect of diosgenin was investigated in mice induced by chronic restraint stress. The effects of diosgenin on behaviors, inflammation, neuroendocrine, neurotrophic function, and gut microbiota were evaluated.

RESULTS

The results showed that diosgenin alleviated the depressive-like behaviors in mice. In addition, diosgenin was found to reduce serum concentrations of proinflammatory cytokines and the activity of the hypothalamic-pituitary-adrenal (HPA) axis. Besides, diosgenin could activate hippocampal brain-derived neurotrophic factor (BDNF)/TrkB/ERK/CREB signaling pathway and improve the expression of postsynaptic protein PSD95. Meanwhile, the neurogenesis which was inhibited by chronic restraint stress, was totally reversed by diosgenin. Moreover, diosgenin increased the abundance of phylum Firmicutes and the genus Lactobacillus in stressed mice. The results further showed that diosgenin caused a strong correlation between gut microbiota composition and inflammation, the HPA axis activity, or hippocampus neurotrophic function.

LIMITATIONS

Only male mice were used for evaluation in the present study, which limits the understanding of effects of diosgenin on the both sexes. In addition, the results only indicate microbiota at the phylum or genus mediate the regulation of neuroinflammation, neuroendocrine, and neurotrophic function, but does not elucidate how microbiota modulate the systems via their primary or secondary metabolites.

CONCLUSIONS

The present study shows that diosgenin exerts the antidepressant activity, which is associated with the enhancement of neurotrophic function and the inhibition of inflammatory and neuroendocrine activities via the regulation of gut microbiota.

Mastitis: Impact of Dry Period, Pathogens, and Immune Responses on Etiopathogenesis of Disease and its Association with Periparturient Diseases

Mastitis is an inflammation of the mammary gland initiated by pathogenic bacteria. In fact, mastitis is the second most important reason for the culling of cows from dairy herds, after infertility. In this review we focus on various forms of mastitis, including subclinical and clinical mastitis. We also stress the importance of the dry-off period as an important time when pathogenic bacteria might start their insult to the mammary gland. An important part of the review is the negative effects of mastitis on milk production and composition, as well as economic consequences for dairy farms. The two most important groups of bacteria that are involved in infection of the udder, Gram-negative and Gram-positive bacteria, are also discussed. Although all cows have both innate and adaptive immunity against most pathogens, some are more susceptible to the disease than others. That is why we summarize the most important components of innate and adaptive immunity so that the reader understands the specific immune responses of the udder to pathogenic bacteria. One of the most important sections of this review is interrelationship of mastitis with other diseases, especially retained placenta, metritis and endometritis, ketosis, and laminitis. Is mastitis the cause or the consequence of this disease? Finally, the review concludes with treatment and preventive approaches to mastitis.

Behavioral design interventions for the promotion of wellbeing among Filipino healthcare workers during the COVID-19 pandemic

Frontline healthcare workers (HCWs) in hospitals have been among the most vulnerable members of the population since the COVID-19 pandemic, affecting not only physical but also mental health. Complementary approaches to providing information for HCWs on taking care of their mental health need development and scaling-up. Behaviorally designed interventions take into consideration the context, resistance, and impact in facilitating behavior change in a specific target segment towards an intended aspiration. The behaviorally designed interventions sought to build individual resilience aligned with the Mental Health and Psychosocial Support Services framework. These included strengthening the provision of non-specialized services and community support among the range of interventions that address mental health problems. These benefit the vulnerable sectors of the population who are at most risk of experiencing chronic stress. Scaling-up of low-cost and subtle tools is a worthy investment for government institutions to ensure that HCWs are continuously supported so they can continue to provide adequate and quality care to those afflicted by COVID-19.

The Future of Targeted Treatment of Primary Sjögren's Syndrome: A Focus on Extra-Glandular Pathology

Primary Sjögren's syndrome (pSS) is a chronic, systemic autoimmune disease defined by exocrine gland hypofunction resulting in dry eyes and dry mouth. Despite increasing interest in biological therapies for pSS, achieving FDA-approval has been challenging due to numerous complications in the trials. The current literature lacks insight into a molecular-target-based approach to the development of biological therapies. This review focuses on novel research in newly defined drug targets and the latest clinical trials for pSS treatment. A literature search was conducted on ClinicalTrials.gov using the search term "Primary Sjögren's syndrome". Articles published in English between 2000 and 2021 were included. Our findings revealed potential targets for pSS treatment in clinical trials and the most recent advances in understanding the molecular mechanisms underlying the pathogenesis of pSS. A prominent gap in current trials is in overlooking the treatment of extraglandular symptoms such as fatigue, depression, and anxiety, which are present in most patients with pSS. Based on dryness and these symptom-directed therapies, emerging biological agents targeting inflammatory cytokines, signal pathways, and immune reaction have been studied and their efficacy and safety have been proven. Novel therapies may complement existing non-pharmacological methods of alleviating symptoms of pSS. Better grading systems that add extraglandular symptoms to gauge disease activity and severity should be created. The future of pSS therapies may lie in gene, stem-cell, and tissue-engineering therapies.

Mapping Welfare: Location Determining Techniques and Their Potential for Managing Cattle Welfare—A Review

Several studies have suggested that precision livestock farming (PLF) is a useful tool for animal welfare management and assessment. Location, posture and movement of an individual are key elements in identifying the animal and recording its behaviour. Currently, multiple technologies are available for automated monitoring of the location of individual animals, ranging from Global Navigation Satellite Systems (GNSS) to ultra-wideband (UWB), RFID, wireless sensor networks (WSN) and even computer vision. These techniques and developments all yield potential to manage and assess animal welfare, but also have their constraints, such as range and accuracy. Combining sensors such as accelerometers with any location determining technique into a sensor fusion system can give more detailed information on the individual cow, achieving an even more reliable and accurate indication of animal welfare. We conclude that location systems are a promising approach to determining animal welfare, especially when applied in conjunction with additional sensors, but additional research focused on the use of technology in animal welfare monitoring is needed.

Musculoskeletal Pain Management and Patient Mental Health and Well-being

Orthopaedic trauma patients have high rates of psychiatric disorders, which put them at risk for worse outcomes after injury and surgery, including worse pain. Mental health conditions, such as depression and anxiety, can affect the perception of pain. Pain can also exacerbate or contribute to the development of mental illness after injury. Interventions to address both mental health and pain among orthopaedic trauma patients are critical. Balancing safety and comfort amid a drug overdose epidemic is challenging, and many clinicians do not feel comfortable addressing mental health or have the resources necessary. We reviewed the literature on the complex relationship between pain and mental health and presented examples of scalable and accessible interventions that can be implemented to promote the health and recovery of our patients. Interventions described include screening for depression in the orthopaedic trauma clinic and the emergency department or inpatient setting during injury and using a comprehensive and evidence-based multimodal pain management regimen that blends pharmacologic alternatives to opioids and physical and cognitive strategies to manage pain.

Long Covid brain fog: a neuroinflammation phenomenon?

Neuroinflammation is a process triggered by an attack on the immune system. Activation of microglia in response to an immune system challenge can lead to a significant impact on cognitive processes, such as learning, memory and emotional regulation. Long Covid is an ongoing problem, affecting an estimated 1.3 million people within the UK alone, and one of its more significant, and as yet unexplained, symptoms is brain fog. Here, we discuss the potential role of neuroinflammation in Long Covid cognitive difficulties. Inflammatory cytokines have been found to play a significant role in reductions in LTP and LTD, a reduction in neurogenesis, and in dendritic sprouting. The potential behavioural consequences of such impacts are discussed. It is hoped that this article will allow for greater examination of the effects of inflammatory factors on brain function, most particularly in terms of their role in chronic conditions.

Infection increases activity via Toll dependent and independent mechanisms in Drosophila melanogaster

Host behavioural changes are among the most apparent effects of infection. ‘Sickness behaviour’ can involve a variety of symptoms, including anorexia, depression, and changed activity levels. Here, using a real-time tracking and behavioural profiling platform, we show that in Drosophila melanogaster, several systemic bacterial infections cause significant increases in physical activity, and that the extent of this activity increase is a predictor of survival time in some lethal infections. Using multiple bacteria and D. melanogaster immune and activity mutants, we show that increased activity is driven by at least two different mechanisms. Increased activity after infection with Micrococcus luteus, a Gram-positive bacterium rapidly cleared by the immune response, strictly requires the Toll ligand spätzle. In contrast, increased activity after infection with Francisella novicida, a Gram-negative bacterium that cannot be cleared by the immune response, is entirely independent of both Toll and the parallel IMD pathway. The existence of multiple signalling mechanisms by which bacterial infections drive increases in physical activity implies that this effect may be an important aspect of the host response.

Sickness behaviours are often observed during infection. Animals have been shown to change their feeding, mating, social and resting (sleeping) behaviours in response to infection. We show here that fruit-flies infected with bacteria respond by increasing their physical activity and decreasing the amount of time spent sleeping. This increase in activity is seen in some, but not all, bacterial infections, and appears to be driven by at least two different mechanisms: with some bacteria, activating the immune response is the only requirement to induce increased activity, while other bacteria induce increased activity independently of known immune detection pathways. The biological role of increased activity is unclear; flies in the wild may be driven to flee sites where infection risk or pathogen burden is high. Alternatively, increased activity could serve a less direct anti-microbial function. For example, active animals may be more likely to encounter potential mates or food resource.