Brain interleukin-1β and the intrinsic receptor antagonist control peripheral Toll-like receptor 3-mediated suppression of spontaneous activity in rats

Adolescent intermittent ethanol (AIE) sensitized fever in male Sprague Dawley rats exposed to poly I:C in adulthood

Fever plays an indispensable role in host defense processes and is used as a rapid index of infection severity. Unfortunately, there are also substantial individual differences in fever reactions with biological sex, immunological history, and other demographic variables contributing to adverse outcomes of infection. The present series of studies were designed to test the hypothesis that a history of adolescent alcohol misuse may be a latent experiential variable that determines fever severity using polyinosinic:polycytidylic acid (poly I:C), a synthetic form of double-stranded RNA that mimics a viral challenge. Adult male and female Sprague Dawley rats were injected with 0 (saline) or 4 mg/kg poly I:C to first establish sex differences in fever sensitivity in Experiment 1 using implanted radiotelemetry devices for remote tracking. In Experiments 2 and 3, adolescent males and females were exposed to either water or ethanol (0 or 4 g/kg intragastrically, 3 days on, 2 days off, ∼P30-P50, 4 cycles/12 exposures total). After a period of abstinence, adult rats (∼P80-96) were then challenged with saline or poly I:C, and fever induction and maintenance were examined across a prolonged time course of 8 h using implanted probes. In Experiments 4 and 5, adult male and female subjects with a prior history of adolescent water or adolescent intermittent ethanol (AIE) were given saline or poly I:C, with tissue collected for protein and gene expression analysis at 5 h post-injection. Initial sex differences in fever sensitivity were minimal in response to the 4 mg/kg dose of poly I:C in ethanol-naïve rats. AIE exposed males injected with poly I:C showed a sensitized fever response as well as enhanced TLR3, IκBα, and IL-1β expression in the nucleus of the solitary tract. Other brain regions related to thermoregulation and peripheral organs such as spleen, liver, and blood showed generalized immune responses to poly I:C, with no differences evident between AIE and water-exposed males. In contrast, AIE did not affect responsiveness to poly I:C in females. Thus, the present findings suggest that adolescent binge drinking may produce sex-specific and long-lasting effects on fever reactivity to viral infection, with preliminary evidence suggesting that these effects may be due to centrally-mediated changes in fever regulation rather than peripheral immunological mechanisms.

Metabolomic profiling of cancer-related fatigue involved in cachexia and chemotherapy

Patients with advanced cancer are frequently burdened with a severe sensation of fatigue called cancer-related fatigue (CRF). CRF is induced at various stages and treatments, such as cachexia and chemotherapy, and reduces the overall survival of patients. Objective and quantitative assessment of CRF could contribute to the diagnosis and prediction of treatment efficacy. However, such studies have not been intensively performed, particularly regarding metabolic profiles. Here, we conducted plasma metabolomics of 15 patients with urological cancer. The patients with and without fatigue, including those with cachexia or chemotherapy-induced fatigue, were compared. Significantly lower concentrations of valine and tryptophan were observed in fatigued patients than in non-fatigued patients. In addition, significantly higher concentrations of polyamine pathway metabolites were observed in patients with fatigue and cachexia than in those without cachexia. Patients with exacerbated fatigue due to chemotherapy showed significantly decreased cysteine and methionine metabolism before chemotherapy compared with those without fatigue exacerbation. These findings suggest that plasma metabolic profiles could help improve the diagnosis and monitoring of CRF.

Screening Single Nucleotide Polymorphisms Predicting the Efficacy of Electroacupuncture for Fatigue Treatment in Patients with Breast Cancer Following Adjuvant Chemotherapy

Chemotherapy-induced fatigue reduces not only the quality of life of patients but also effect their recurrence-free survival rate. Although electroacupuncture can relieve fatigue, it has limited affect on some patients. Therefore, appropriate biomarkers are needed to help screen patients who can benefit from electroacupuncture treatment of fatigue. We conducted this study to explore the predictive ability of SNPs on the efficacy of electroacupuncture in the treatment of fatigue in patients with breast cancer after adjuvant chemotherapy. Our study included breast cancer patients with fatigue after receiving paclitaxel and/or anthracycline based adjuvant chemotherapy. The patients were divided into the electroacupuncture group and the control group. The electroacupuncture treatment group received adjuvant chemotherapy and electroacupuncture treatment, while the control group only received adjuvant chemotherapy, and then compared the fatigue relief degree of two groups. In addition, we used NCBI dbSNP and PharmGKB databases to select fatigue related genes and their SNPs. We collected peripheral blood from the included patients for SNPs typing, and recorded the efficacy of electroacupuncture to analyzed the correlation between different SNPs and therapeutic efficacy. The side effects of electroacupuncture treatment were also recorded. 76 patients in the electroacupuncture group and 48 patients in the control group were enrolled. In the electroacupuncture group, 63 patients (82.9%) experienced moderate to severe fatigue (BFI score > 3). After electroacupuncture treatment, the number of patients with a BFI score of > 3 was 46 (60.5%). Therefore, the fatigue symptoms of 26.9% patients were significantly improved (P < 0.05). In the control group, which did not receive electroacupuncture treatment, 40 of 48 patients had a BFI score of > 3. Following the same observation time used in the electroacupuncture group, 36 patients had a BFI score of > 3 points. Thus, fatigue was not significantly relieved in the control group (83.3% vs. 75.0%, P > 0.05). We included 56 patients in our analysis of the correlation between SNPs and electroacupuncture treatment effects. We divided the patients into an effective group and ineffective group according to therapeutic effects. Our results indicated that the effective rate of electroacupuncture treatment with IL1A rs3783550 AC and CC genotypes was higher than that with other genotypes (AC: 84.6%, CC: 81.8%, AA: 33.0%, P < 0.05). Similarly, the effective rate of electroacupuncture treatment with HTR1A rs6295 GG and CC genotypes was higher than that with other genotypes (GG: 63.0%, CC: 55.6%, GC: 18.2%, P < 0.05). However, no other genotypes were related to the effect of electroacupuncture treatment on fatigue. Our result showed that electroacupuncture has therapeutic effect on fatigue after adjuvant chemotherapy for breast cancer and the side effects are tolerable. In addition, IL1A rs3763550 and HTR1A rss6295 can predict the therapeutic effect of electroacupuncture on fatigue after adjuvant chemotherapy in breast cancer, which helps to better screen patients who can benefit from electroacupuncture treatment.

Regional neuroinflammation induced by peripheral infection contributes to fatigue-like symptoms: a [18F]DPA-714 positron emission tomography study in rats

Introduction

A series of symptoms, including fever, widespread pain, fatigue, and even ageusia, have frequently been reported in the context of various infections, such as COVID-19. Although the pathogenic mechanisms underlying an infection causing fever and pain have been well established, the mechanisms of fatigue induced by infection in specific brain regions remain unclear.

Methods

To elucidate whether and how the peripheral infection cause fatigue via regional neuroinflammation, we performed a brain-wide investigation of neuroinflammation in a peripheral pseudoinfection rat model using [18F]DPA-714 positron emission tomography (PET) imaging analysis, in which the polyriboinosinic: polyribocytidylic acid (poly I:C) was intraperitoneally injected.

Results

Transient fever lasting for several hours and subsequent suppression of spontaneous activity lasting a few days were induced by poly I:C treatment. Significant increase in plasma interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α were observed at 2 and 4 h following poly I:C treatment. PET imaging analysis revealed that the brain uptake of [18F]DPA-714 was significantly increased in several brain regions one day after poly I:C treatment, such as the dorsal raphe (DR), parvicellular part of red nucleus (RPC), A5 and A7 noradrenergic nucleus, compared with the control group. The accumulation of [18F]DPA-714 in the DR, RPC and A5 was positively correlated with subsequent fatigue-like behavior, and that in the A7 tended to positively correlate with fever.

Discussion

These findings suggest that peripheral infection may trigger regional neuroinflammation, which may cause specific symptoms such as fatigue. A similar mechanism might be involved in COVID-19.

An analysis of patients with a chief complaint of difficulty moving

Objective: There have been few reports in English medical journals analyzing patients with difficulty moving. Herein, we conducted a retrospective survey of emergency patients admitted to our hospital with the chief complaint of difficulty moving, to clarify the clinical characteristics of the frequency, causative disease, and outcome in these patients. Patients and Methods: Between August 2017 and October 2021, we surveyed the patient database maintained by our department, covering cases in which the main complaint at the time of patient transport by ambulance to our hospital was difficulty moving. Results: In 111 cases, the patient's primary complaint was difficulty moving or adynamia. Patients included 59 males and 52 females, with a mean age of 76.3 years old. The most frequent diagnosis in these patients was rhabdomyolysis, followed by infection, body temperature abnormalities, electrolyte disorder, blood glucose abnormality, hypoxia, and renal failure. Trauma and various other diseases, such as stroke and malignancy, were also found to be causative diseases. After discharge from the hospital, the number of patients with a dependent status was greater than those with an independent status. Conclusion: Patients with difficulty moving were primarily elderly, and had a variety of causative diseases. Therefore, multiple approaches are required to manage these patients.

Cerebral dysfunctions caused by sepsis during ageing

Systemic inflammation elicited by sepsis can induce an acute cerebral dysfunction known as sepsis-associated encephalopathy (SAE). Recent evidence suggests that SAE is common but shows a dynamic trajectory over time. Half of all patients with sepsis develop SAE in the intensive care unit, and some survivors present with sustained cognitive impairments for several years after initial sepsis onset. It is not clear why some, but not all, patients develop SAE and also the factors that determine the persistence of SAE. Here, we first summarize the chronic pathology and the dynamic changes in cognitive functions seen after the onset of sepsis. We then outline the cerebral effects of sepsis, such as neuroinflammation, alterations in neuronal synapses and neurovascular changes. We discuss the key factors that might contribute to the development and persistence of SAE in older patients, including premorbid neurodegenerative pathology, side effects of sedatives, renal dysfunction and latent virus reactivation. Finally, we postulate that some of the mechanisms that underpin neuropathology in SAE may also be relevant to delirium and persisting cognitive impairments that are seen in patients with severe COVID-19.

Animal Models for Neuroinflammation and Potential Treatment Methods

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic disease of unknown etiology and without effective treatment options. The onset of ME/CFS is often associated with neuroinflammation following bacterial or viral infection. A positron emission tomography imaging study revealed that the degree of neuroinflammation was correlated with the severity of several symptoms in patients with ME/CFS. In animal studies, lipopolysaccharide- and polyinosinic-polycytidylic acid-induced models are thought to mimic the pathological features of ME/CFS and provoke neuroinflammation, characterized by increased levels of proinflammatory cytokines and activation of microglia. In this review, we described the anti-inflammatory effects of three compounds on neuroinflammatory responses utilizing animal models. The findings of the included studies suggest that anti-inflammatory substances may be used as effective therapies to ameliorate disease symptoms in patients with ME/CFS.

[Mechanisms underlying chronic fatigue, a symptom too often overlooked]

Acute fatigue after exertion, like acute inflammation after injury, is useful for our body. On the contrary, both chronic fatigue and chronic inflammation are deleterious, and they are associated in many diseases. In this first part, we will analyze different immune phenomena (bystander activation, memory of the innate immune system, link with the intestinal microbiota) involved in triggering chronic inflammation. This review aims at looking for links between different signs and symptoms associated with chronic fatigue, as well as between different diseases in which severe chronic fatigue can manifest. Possible underlying mechanisms for these phenomena are discussed. This is a proposal made by a researcher, with no clinical experience, to doctors confronted with an entity that is still largely mysterious. The link between chronic inflammation, neuroinflammation and fatigue will be examined in a second part.

Orange peel extract reduces the inflammatory state of skeletal muscle after downhill running via an increase in IL-1RA

It has been reported that orange peel extract (OPE) and the 4 major polymethoxyflavones (PMFs) in OPE have a protective effect against downhill running (DR)-induced skeletal muscle inflammation. However, the mechanism is not well understood. We investigated the potential of OPE and PMF compounds for increasing anti-inflammatory cytokine levels. The plasma interleukin-1 receptor antagonist (IL-1RA) level was increased 1 and 8 h after OPE administration in rats. Nobiletin induced the secretion of IL-1RA from C2C12 myotubes. In the inflammatory state of skeletal muscle after DR, OPE administration reduced nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) expression, NF-κB-DNA binding, and monocyte chemotactic protein-1 mRNA levels, but these effects were all abrogated by the intravenous administration of IL-1RA neutralizing antibody. These results indicated that OPE reduces skeletal muscle inflammatory state after DR via an increase in IL-1RA, and that IL-1 receptor signaling is important for skeletal muscle inflammation after DR.

[Imaging and Manipulation of Stem and Progenitor Cells for Revealing the Novel Mechanism of Local Tissue Maintenance in the Brain]

We have been investigating the physiological and pathological roles of stem cells and progenitor cells in the central nervous system using multimodal imaging methods, including positron emission tomography (PET), in vivo optical imaging, and light as well as electron microscopy. Furthermore, we generated transgenic rats for selective ablation of these cells. Imaging studies have demonstrated the proliferation and dynamics of neural stem cells in neurogenic regions and glial progenitor cells expressing a chondroitin sulfate proteoglycan (neuron-glial antigen 2; NG2) in the brain of adult rodents. Glial progenitor cells change their direction of differentiation into mature oligodendrocytes or astrocytes by neural activity following their proliferation. This phenomenon was thought to control the local tissue structure for maintenance of moderate neural activity. Furthermore, selective ablation of glial progenitor cells in the brain induced defects of neurons via neuroinflammation with microglial activation and proinflammatory cytokine production in the region. Thus, we have proposed a novel concept that glial progenitor cells regulate the neuro-immune system in the central nervous system, in addition to their role as germinal cells, giving rise to mature glial cells. Neuroinflammation is associated with the onset and progression of depression, chronic fatigue syndrome, and neurodegenerative diseases, including Alzheimer's disease. Anti-inflammatory effects of glial progenitor cells might bring about the possibility of these cells as the new therapeutic targets for such neurological disorders.

LimeMap: a comprehensive map of lipid mediator metabolic pathways

Lipid mediators are major factors in multiple biological functions and are strongly associated with disease. Recent lipidomics approaches have made it possible to analyze multiple metabolites and the associations of individual lipid mediators. Such systematic approaches have enabled us to identify key changes of biological relevance. Against this background, a knowledge-based pathway map of lipid mediators would be useful to visualize and understand the overall interactions of these factors. Here, we have built a precise map of lipid mediator metabolic pathways (LimeMap) to visualize the comprehensive profiles of lipid mediators that change dynamically in various disorders. We constructed the map by focusing on ω-3 and ω-6 fatty acid metabolites and their respective metabolic pathways, with manual curation of referenced information from public databases and relevant studies. Ultimately, LimeMap comprises 282 factors (222 mediators, and 60 enzymes, receptors, and ion channels) and 279 reactions derived from 102 related studies. Users will be able to modify the map and visualize measured data specific to their purposes using CellDesigner and VANTED software. We expect that LimeMap will contribute to elucidating the comprehensive functional relationships and pathways of lipid mediators.

Panaxytriol Inhibits Lipopolysaccharide-Induced Microglia Activation in Brain Inflammation in Vivo

Brain inflammation is a pathological characteristic of neurodegenerative diseases. In this condition, excessively activated microglia elevate proinflammatory mediator levels. We previously reported that panaxytriol inhibited lipopolysaccharide (LPS)-induced microglia activation in vitro. However, the effects of panaxytriol on microglia activation in vivo require confirmation. In the present study, we found that panaxytriol suppressed both microglia and astrocyte activation by injected LPS intracerebrally to mice with LPS-induced brain inflammation. Panaxytriol was more effective on microglia than astrocytes. Moreover, panaxytriol tended to reduce LPS-induced spontaneous motor activity dysfunction. These results suggested that panaxytriol could improve brain health by suppressing microglia activation in neurodegenerative diseases.

Basic pharmacological mechanisms and clinical evidence of the efficacy of hochuekkito against infectious diseases and its potential for use against COVID‐19

Background

Hochuekkito extract (HET) has multiple effects through the digestive and immune systems, including for acute viral infection and chronic inflammation. We review basic pharmacological and clinical researches of HET and discuss the effects of HET against the pandemic COVID‐19.

Methods

We reviewed pharmacological studies from 1996 to 30 April 2020 that used experimental animals orally treated with HET and randomized controlled trials (RCTs) from 2000 to 30 April 2020.

Results

Altogether, 64 pharmacological studies reported immuno‐stimulatory effects against infection and cancer, immuno‐modulative effects against allergy and some inflammatory diseases, and ameliorating effects against exhaustion and frailty. Nine RCTs showed improvement of pulmonary Mycobacterium avium complex disease on chest X‐ray; improved systemic inflammation, nutrition, and quality of life of patients with chronic obstructive pulmonary disease and a decrease in the number getting common cold and exacerbations; reduction of soluble interleukin‐2 receptor and the serum cortisol concentration of postoperative patients; a reduction of the incidence of inflammatory complications and C‐reactive protein elevation after cerebrovascular disease; a reduction of the volume of steroid and tacrolimus during the treatment of atopic dermatitis; a healing effect for intractable chronic wounds; improvement of the physical status of elderly weak patients; and improvement of the fatigue level of cancer patients.

Conclusion

CODIV‐19 is characterized by high risk for the aged and people with other disease complications, cytokine hyperactivity in the severe stage, and sequelae in the recovery stage. Considering the immune‐stimulative/modulative effects of HET on inflammatory conditions and against exhaustion and frailty, it may be useful for prevention, treatment, and recovery from COVID‐19.

Homeostatic disturbance of thermoregulatory functions in rats with chronic fatigue

Chronic fatigue syndrome (CFS) is characterized by long-lasting fatigue, and a range of symptoms, and is involved in homeostasis disruption. CFS patients frequently complain of low grade fever or chill even under normal body temperature indicating that thermosensory or thermoregulatory functions might be disturbed in CFS. However, little is known about the detailed mechanisms. To elucidate whether and how thermoregulatory function was altered during the development of chronic fatigue, we investigated temporal changes in body temperature with advance of fatigue accumulation in a chronic fatigue rat model using a wireless transponder. Our findings demonstrated that the body temperature was adaptively increased in response to fatigue loading in the early phase, but unable to retain in the late phase. The tail heat dissipation was often observed and the frequency of tail heat dissipation gradually increased initially, then decreased. In the late phase of fatigue loading, the body temperature for the tail heat dissipation phase decreased to a value lower than that for the non-dissipation phase. These results suggest that adaptive changes in thermoregulatory function occurred with fatigue progression, but this system might be disrupted by long-lasting fatigue, which may underlie the mechanism of fatigue chronification.

Effects of Capsinoids on Daily Physical Activity, Body Composition and Cold Hypersensitivity in Middle-Aged and Older Adults: A Randomized Study

Sedentary/inactive lifestyle leads middle-aged and older adults to metabolic syndrome and frailty. Capsinoids from nonpungent chili pepper cultivar have been reported to reduce body fat mass, promote metabolism, and improve unidentified complaints of chills. Additionally, they have an anti-inflammation effect; therefore, we hypothesized that continuous oral ingestion of capsinoids alleviates age-related inflammation in the brain and improves the physical activity (PA) in middle-aged and older adults. In our double-blind human study, 69 participants (17 male, 52 female; mean age: 74.1 ± 7.7 years; range: 52–87 years) were administered either 9 mg of capsinoids which were extracted from pepper fruit variety CH-19 Sweet (Capsicum anuum L.) (CP group), or a placebo (PL group) daily over a 3 month period. In an animal study, PA and inflammation-related mRNA expression in the brain were examined in 5-week (young) and 53-week (old) aged mice fed a diet with or without 0.3% dihydrocapsiate, a type of capsinoids, for 12 weeks. In a human study, capsinoids intake did not increase the amount of light-to-moderate PA less than 6.0 metabolic equivalents (METs) (CP: 103.0 ± 28.2 at baseline to 108.2 ± 28.3 at 12 weeks; PL: 104.6 ± 19.8 at baseline to 115.2 ± 23.6 at 12 weeks, METs × hour/week); however, in participants exhibiting an inactive lifestyle, it showed significant increase (CP: 84.5 ± 17.2 at baseline to 99.2 ± 24.9 at 12 weeks; PL: 99.7 ± 23.3 at baseline to 103.8 ± 21.9 at 12 weeks). The energy expenditure in physical activity also improved in the inactive CP group (CP: 481.2 ± 96.3 at baseline to 562.5 ± 145.5 at 12 weeks; PL: 536.8 ± 112.2 at baseline to 598.6 ± 127.6 at 12 weeks; kcal/day). In all participants, CP showed reduced waist circumference, percent body fat, and visceral fat volume; in addition, chills were eased in subjects aged 80 years and older. The older mice fed capsinoids showed increased locomotion activity, decreased inflammation, and oxidative stress in the brain. The results suggest that the continuous oral ingestion of capsinoids gains PA through anti-inflammation effect in the brain as well as reduces fat accumulation and chills in inactive and older humans.

An Association of Serotonin with Pain Disorders and Its Modulation by Estrogens

Ovarian hormones play an important role in pain perception, and are responsible, at least in part, for the pain threshold differences between the sexes. Modulation of pain and its perception are mediated by neurochemical changes in several pathways, affecting both the central and peripheral nervous systems. One of the most studied neurotransmitters related to pain disorders is serotonin. Estrogen can modify serotonin synthesis and metabolism, promoting a general increase in its tonic effects. Studies evaluating the relationship between serotonin and disorders such as irritable bowel syndrome, fibromyalgia, migraine, and other types of headache suggest a clear impact of this neurotransmitter, thereby increasing the interest in serotonin as a possible future therapeutic target. This literature review describes the importance of substances such as serotonin and ovarian hormones in pain perception and illustrates the relationship between those two, and their direct influence on the presentation of the aforementioned pain-related conditions. Additionally, we review the pathways and receptors implicated in each disorder. Finally, the objective was to stimulate future pharmacological research to experimentally evaluate the potential of serotonin modulators and ovarian hormones as therapeutic agents to regulate pain in specific subpopulations.

Viral Mimetic-Induced Inflammation Abolishes Q-Pathway, but Not S-Pathway, Respiratory Motor Plasticity in Adult Rats

Inflammation arises from diverse stimuli eliciting distinct inflammatory profiles, yet little is known about the effects of different inflammatory stimuli on respiratory motor plasticity. Respiratory motor plasticity is a key feature of the neural control of breathing and commonly studied in the form of phrenic long-term facilitation (pLTF). At least two distinct pathways can evoke pLTF with differential sensitivities to bacterial-induced inflammation. The Q-pathway is abolished by bacterial-induced inflammation, while the S-pathway is inflammation-resistant. Since viral-induced inflammation is common and elicits distinct temporal inflammatory gene profiles compared to bacterial inflammation, we tested the hypothesis that inflammation induced by a viral mimetic (polyinosinic:polycytidylic acid, polyIC) would abolish Q-pathway-evoked pLTF, but not S-pathway-evoked pLTF. Further, we hypothesized Q-pathway impairment would occur later relative to bacterial-induced inflammation. PolyIC (750 μg/kg, i.p.) transiently increased inflammatory genes in the cervical spinal cord (3 h), but did not alter medullary and splenic inflammatory gene expression, suggesting region specific inflammation after polyIC. Dose-response experiments revealed 750 μg/kg polyIC (i.p.) was sufficient to abolish Q-pathway-evoked pLTF at 24 h (17 ± 15% change from baseline, n = 5, p > 0.05). However, polyIC (750 μg/kg, i.p.) at 3 h was not sufficient to abolish Q-pathway-evoked pLTF (67 ± 21%, n = 5, p < 0.0001), suggesting a unique temporal impairment of pLTF after viral-mimetic-induced systemic inflammation. A non-steroidal anti-inflammatory (ketoprofen, 12.5 mg/kg, i.p., 3 h) restored Q-pathway-evoked pLTF (64 ± 24%, n = 5, p < 0.0001), confirming the role of inflammatory signaling in pLTF impairment. On the contrary, S-pathway-evoked pLTF was unaffected by polyIC-induced inflammation (750 μg/kg, i.p., 24 h; 72 ± 25%, n = 5, p < 0.0001) and was not different from saline controls (65 ± 32%, n = 4, p = 0.6291). Thus, the inflammatory-impairment of Q-pathway-evoked pLTF is generalizable between distinct inflammatory stimuli, but differs temporally. On the contrary, S-pathway-evoked pLTF is inflammation-resistant. Therefore, in situations where respiratory motor plasticity may be used as a tool to improve motor function, strategies targeting S-pathway-evoked plasticity may facilitate therapeutic outcomes.

Shared microglial mechanisms underpinning depression and chronic fatigue syndrome and their comorbidities

In 2011, it was reviewed that a) there is a strong co-occurrence between major depression and chronic fatigue syndrome (CFS), with fatigue and physio-somatic symptoms being key symptoms of depression, and depressive symptoms appearing during the course of CFS; and b) the comorbidity between both disorders may in part be explained by activated immune-inflammatory pathways, including increased translocation of Gram-negative bacteria and increased levels of pro-inflammatory cytokines, such as interleukin (IL)-1. Nevertheless, the possible involvement of activated microglia in this comorbidity has remained unclear. This paper aims to review microglial disturbances in major depression, CFS and their comorbidity. A comprehensive literature search was conducted using the PubMed / MEDLINE database to identify studies, which are relevant to this current review. Depressed patients present neuroinflammatory alterations, probably related to microglial activation, while animal models show that a microglial response to immune challenges including lipopolysaccharides is accompanied by depressive-like behaviors. Recent evidence from preclinical studies indicates that activated microglia have a key role in the onset of fatigue. In chronic inflammatory conditions, such as infections and senescence, microglia orchestrate an inflammatory microenvironment thereby causing fatigue. In conclusion, based on our review we may posit that shared immune-inflammatory pathways and especially activated microglia underpin comorbid depression and CFS. As such, microglial activation and neuro-inflammation may be promising targets to treat the overlapping manifestations of both depression and CFS.

Disability as a determinant of fatigue in MS patients

ABSTRACT Fatigue is one of the most frequent and disabling symptoms in multiple sclerosis (MS). Central, psychological, and peripheral factors may contribute to the occurrence of fatigue. Objectives: The current study aimed to evaluate potential fatigue determinants in patients with relapsing-remitting MS with a low functional impairment. Methods: We compared inflammatory markers, respiratory pressures, disability, and quality of life in 39 relapsing-remitting MS patients with and without fatigue. Results: Patients with relapsing-remitting MS with fatigue had higher Expanded Disability Status Scale scores (p = 0.002). We observed a significant association between the results of the Guy Neurological Disability Scale, the Functional Assessment of MS Quality of Life Rating Scale and the presence of fatigue (p < 0.05). Conclusions: The degree of functional impairment is a determinant for the presence of fatigue in MS patients, but respiratory function and inflammatory markers are not.

Role of Prefrontal Cortex Anti- and Pro-inflammatory Cytokines in the Development of Abnormal Behaviors Induced by Disconnection of the Ventral Hippocampus in Neonate Rats

Neonatal disconnection of ventral hippocampus (VH) outputs in rats has been reported to lead to post-pubertal behavioral and synaptic changes of relevance to schizophrenia. Increased oxidative and inflammatory load in the prefrontal cortex (PFC) has been suggested to mediate some of the effects of neonatal VH lesion (NVHL). In this study, we hypothesized that developmental imbalance of anti- and pro-inflammatory factors within the PFC might affect synaptic development thus contributing to the adult NVHL-induced behavioral deficits. Ibotenic acid-induced excitotoxic NVHL was performed in postnatal day (PD) 7 male Sprague-Dawley rats and the mRNA levels of select pro- and anti-inflammatory cytokines were measured in the medial PFC (mPFC) at two developmental time points (PD15 and PD60). We observed a development-specific increase of pro-inflammatory cytokine, interleukin (IL)-1β mRNA at PD15, and an overall reduction in the expression and signaling of transforming growth factor beta 1 (TGF-β1), an anti-inflammatory cytokine, at both PD15 and PD60 in the NVHL animals. These cytokine changes were not seen in the somatosensory cortex (SSC) or tissue surrounding the lesion site. Daily administration of systemic recombinant TGF-β1 from PD7-14 prevented the appearance of hyperlocomotion, deficits in prepulse inhibition (PPI) of startle and social interaction (SI) in post-pubertal (PD60) NVHL rats. Neonatal supplementation of TGF-β1 was also able to attenuate dendritic spine loss in the layer 3 mPFC pyramidal neurons of NVHL animals. These results suggest that early damage of the VH has long-lasting inflammatory consequences in distant connected structures, and that TGF-β1 has potential to confer protection against the deleterious effects of developmental hippocampal damage.

FAAH inhibition attenuates TLR3-mediated hyperthermia, nociceptive- and anxiety-like behaviour in female rats

Aberrant activation of toll-like receptor (TLR)s results in persistent and prolonged neuroinflammation and has been implicated in the pathogenesis and exacerbation of psychiatric and neurodegenerative disorders. TLR3 coordinates the innate immune response to viral infection and recent data have demonstrated that inhibiting fatty acid amide hydrolase (FAAH), the enzyme that primarily metabolizes anandamide, modulates TLR3-mediated neuroinflammation. However, the physiological and behavioural consequences of such modulation are unknown. The present study examined the effect of URB597, a selective FAAH inhibitor, on neuroinflammation, physiological and behavioural alterations following administration of the TLR3 agonist and viral mimetic poly I:C to female rats. URB597 attenuated TLR3-mediated fever, mechanical and cold allodynia, and anxiety-like behaviour in the elevated plus maze and open field arena. There was no effect of URB597 on TLR3-mediated decreases in body weight and no effect in the sucrose preference or forced swim tests. URB597 attenuated the TLR3-mediated increase in the expression of CD11b and CD68, markers of microglia/macrophage activation. In summary, these data demonstrate that enhancing FAAH substrate levels suppresses TLR3-mediated microglia/macrophage activation and associated changes in fever, nociceptive responding and anxiety-related behaviour. These data provide further support for FAAH as a novel therapeutic target for neuroinflammatory disorders.

Effect of central injection of tumor-necrosis factor-like cytokine 1A and interferons on food intake in chicks

In mammals, anorexia accompanying infection is thought to be mediated via cytokines including interleukins, interferons (IFNs), and tumor necrosis factor (TNF). However, there is a lack of related knowledge on birds. Therefore, the purpose of the present study was to determine if cytokines are associated with reduced food intake in chicks (Gallus gallus). Specifically, we evaluated the effects of TNF-like cytokine 1A (TL1A), a member of the TNF family, interferon-α (IFN-α), and interferon-γ (IFN-γ) on food intake. Additionally, the effect of lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid (poly I:C) on cytokine mRNA expression in the diencephalon and spleen was also measured. Intracerebroventricular (ICV) injection of 0.05 or 0.5 μg TL1A, IFN-α, and IFN-γ had no effect on food intake. However, when 1.0 μg each of these factors was evaluated, TL1A significantly decreased food intake at 180 and 240 min after the injection, but IFN-α and IFN-γ had no effect. When chicks received intraperitoneal (IP) injections of 100 μg LPS or 400 μg poly I:C, their food intake was reduced. Diencephalic mRNA expression of TL1A was significantly decreased following IP injection of LPS or poly I:C. Additionally, diencephalic mRNA expression of IFN-γ mRNA was significantly increased by IP injection of LPS but decreased by IP injection of poly I:C. For the spleen, IP injection of LPS and poly I:C both significantly increased TL1A and IFN-γ mRNA expression. In sum, we have provided evidence that central TL1A but not IFN-α or IFN-γ are related to reduction of food intake in chicks, but the role of these cytokines for mediating anorexia associated with infections may differ from mammals.

Astroglial major histocompatibility complex class I following immune activation leads to behavioral and neuropathological changes

In the central nervous system, major histocompatibility complex class I (MHCI) molecules are mainly expressed in neurons, and neuronal MHCI have roles in synapse elimination and plasticity. However, the pathophysiological significance of astroglial MHCI remains unclear. We herein demonstrate that MHCI expression is up-regulated in astrocytes in the medial prefrontal cortex (mPFC) following systemic immune activation by an intraperitoneal injection of polyinosinic-polycytidylic acid (polyI:C) or hydrodynamic interferon (IFN)-γ gene delivery in male C57/BL6J mice. In cultured astrocytes, MHCI/H-2D largely co-localized with exosomes. To investigate the role of astroglial MHCI, H-2D, or sH-2D was expressed in the mPFC of male C57/BL6J mice using an adeno-associated virus vector under the control of a glial fibrillary acidic protein promoter. The expression of astroglial MHCI in the mPFC impaired sociability and recognition memory in mice. Regarding neuropathological changes, MHCI expression in astrocytes significantly activated microglial cells, decreased parvalbumin-positive cell numbers, and reduced dendritic spine density in the mPFC. A treatment with GW4869 that impairs exosome synthesis ameliorated these behavioral and neuropathological changes. These results suggest that the overexpression of MHCI in astrocytes affects microglial proliferation as well as neuronal numbers and spine densities, thereby leading to social and cognitive deficits in mice, possibly via exosomes created by astrocytes.

Glial Activation and Expression of the Serotonin Transporter in Chronic Fatigue Syndrome

Fatigue is commonly reported in a variety of illnesses and has major impact on quality of life. Chronic fatigue syndrome (CFS) is a debilitating syndrome of unknown etiology. The clinical symptoms include problems in neuroendocrine, autonomic, and immune systems. It is becoming clear that the brain is the central regulator of CFS. For example, neuroinflammation, especially induced by activation of microglia and astrocytes, may play a prominent role in the development of CFS, though little is known about molecular mechanisms. Many possible causes of CFS have been proposed. However, in this mini-review, we summarize evidence for a role for microglia and astrocytes in the onset and the maintenance of immunologically induced CFS. In a model using virus mimicking synthetic double-stranded RNA, infection causes sequential signaling such as increased blood brain barrier (BBB) permeability, microglia/macrophage activation through Toll-like receptor 3 (TLR3) signaling, secretion of IL-1β, upregulation of the serotonin transporter (5-HTT) in astrocytes, reducing extracellular serotonin (5-HT) levels and hence reduced activation of 5-HT_1A receptor subtype. Hopefully, drug discovery targeting these pathways may be effective for CFS therapy.

Deconstructing the traditional Japanese medicine "Kampo": compounds, metabolites and pharmacological profile of maoto, a remedy for flu-like symptoms

Pharmacological activities of the traditional Japanese herbal medicine (Kampo) are putatively mediated by complex interactions between multiple herbal compounds and host factors, which are difficult to characterize via the reductive approach of purifying major bioactive compounds and elucidating their mechanisms by conventional pharmacology. Here, we performed comprehensive compound, pharmacological and metabolomic analyses of maoto, a pharmaceutical-grade Kampo prescribed for flu-like symptoms, in normal and polyI:C-injected rats, the latter suffering from acute inflammation via Toll-like receptor 3 activation. In total, 352 chemical composition-determined compounds (CCDs) were detected in maoto extract by mass spectrometric analysis. After maoto treatment, 113 CCDs were newly detected in rat plasma. Of these CCDs, 19 were present in maoto extract, while 94 were presumed to be metabolites generated from maoto compounds or endogenous substances such as phospholipids. At the phenotypic level, maoto ameliorated the polyI:C-induced decrease in locomotor activity and body weight; however, body weight was not affected by individual maoto components in isolation. In accordance with symptom relief, maoto suppressed TNF-α and IL-1β, increased IL-10, and altered endogenous metabolites related to sympathetic activation and energy expenditure. Furthermore, maoto decreased inflammatory prostaglandins and leukotrienes, and increased anti-inflammatory eicosapentaenoic acid and hydroxyl-eicosapentaenoic acids, suggesting that it has differential effects on eicosanoid metabolic pathways involving cyclooxygenases, lipoxygenases and cytochrome P450s. Collectively, these data indicate that extensive profiling of compounds, metabolites and pharmacological phenotypes is essential for elucidating the mechanisms of herbal medicines, whose vast array of constituents induce a wide range of changes in xenobiotic and endogenous metabolism.

Pharmacological activities of Kampo, or traditional Japanese herbal medicine, are putatively mediated by complex interactions between the plant-derived compounds and endogenous molecules. To elucidate these properties, we performed comprehensive phytochemical profiling, and pharmacological and metabolomic analyses of maoto, an herbal remedy for flu-like symptoms. In the plasma of maoto-treated rats, we detected maoto-derived compounds, metabolites produced from the chemical transformation of maoto compounds by host metabolism and gut microbes, and endogenous metabolites that were appeared following maoto administration. In an acute inflammatory rat model, maoto ameliorated symptoms of sickness behavior, suppressed inflammatory cytokines, and extensively affected common metabolites and lipid mediators. These data suggest that the diverse chemical composition of Kampo broadly affects the host’s endogenous metabolism and exerts specific pharmacological effects.

NG2 glial cells regulate neuroimmunological responses to maintain neuronal function and survival

NG2-expressing neural progenitor cells (i.e., NG2 glial cells) maintain their proliferative and migratory activities even in the adult mammalian central nervous system (CNS) and produce myelinating oligodendrocytes and astrocytes. Although NG2 glial cells have been observed in close proximity to neuronal cell bodies in order to receive synaptic inputs, substantive non-proliferative roles of NG2 glial cells in the adult CNS remain unclear. In the present study, we generated NG2-HSVtk transgenic rats and selectively ablated NG2 glial cells in the adult CNS. Ablation of NG2 glial cells produced defects in hippocampal neurons due to excessive neuroinflammation via activation of the interleukin-1 beta (IL-1β) pro-inflammatory pathway, resulting in hippocampal atrophy. Furthermore, we revealed that the loss of NG2 glial cell-derived hepatocyte growth factor (HGF) exacerbated these abnormalities. Our findings suggest that NG2 glial cells maintain neuronal function and survival via the control of neuroimmunological function.

Interleukin-1 as a mediator of fatigue in disease: a narrative review

Fatigue is commonly reported in a variety of illnesses, and it has major impact on quality of life. Previously, it was thought that fatigue originates in the skeletal muscles, leading to cessation of activity. However, more recently, it has become clear that the brain is the central regulator of fatigue perception. It has been suggested that pro-inflammatory cytokines, especially interleukin-1 alpha (IL-1α) and interleukin-1 beta (IL-1β), play a prominent role in the development of central fatigue, and several studies have been performed to elucidate the connection between inflammation and these central processes.In this narrative review, mechanisms of action of IL-1 are described, with special attention to its effect on the central nervous system. In addition, we present a summary of studies that (i) investigated the relationship between circulating IL-1α and IL-1β and fatigue severity and/or (ii) evaluated the effect of inhibiting IL-1 on fatigue. We aim to improve the understanding of fatigue in both inflammatory and non-inflammatory illnesses, which could help develop strategies to treat fatigue more effectively.Reviewing the studies that have been performed, it appears that there is a limited value of measuring circulating IL-1. However, inhibiting IL-1 has a positive effect on severe fatigue in most studies that have been conducted.

Suppression of Locomotor Activity in Female C57Bl/6J Mice Treated with Interleukin-1β: Investigating a Method for the Study of Fatigue in Laboratory Animals

Fatigue is a disabling symptom in patients with multiple sclerosis and Parkinson’s Disease, and is also common in patients with traumatic brain injury, cancer, and inflammatory disorders. Little is known about the neurobiology of fatigue, in part due to the lack of an approach to induce fatigue in laboratory animals. Fatigue is a common response to systemic challenge by pathogens, a response in part mediated through action of the pro-inflammatory cytokine interleukin-1 beta (IL-1β). We investigated the behavioral responses of mice to IL-1β. Female C57Bl/6J mice of 3 ages were administered IL-1β at various doses i.p. Interleukin-1β reduced locomotor activity, and sensitivity increased with age. Further experiments were conducted with middle-aged females. Centrally administered IL-1β dose-dependently reduced locomotor activity. Using doses of IL-1β that caused suppression of locomotor activity, we measured minimal signs of sickness, such as hyperthermia, pain or anhedonia (as measured with abdominal temperature probes, pre-treatment with the analgesic buprenorphine and through sucrose preference, respectively), all of which are responses commonly reported with higher doses. We found that middle-aged orexin^-/- mice showed equivalent effects of IL-1β on locomotor activity as seen in wild-type controls, suggesting that orexins are not necessary for IL-1β -induced reductions in wheel-running. Given that the availability and success of therapeutic treatments for fatigue is currently limited, we examined the effectiveness of two potential clinical treatments, modafinil and methylphenidate. We found that these treatments were variably successful in restoring locomotor activity after IL-1β administration. This provides one step toward development of a satisfactory animal model of the multidimensional experience of fatigue, a model that could allow us to determine possible pathways through which inflammation induces fatigue, and could lead to novel treatments for reversal of fatigue.

Characterization of interleukin-1β as a proinflammatory cytokine in grass carp (Ctenopharyngodon idella)

Interleukin-1β (IL-1β) is a well-characterized cytokine that plays key roles in cellular responses to infection, inflammation, and immunological challenges in mammals. In this study, we identified and analyzed a grass carp (Ctenopharyngodon idella) ortholog of IL-1β (gcIL-1β), examined its expression patterns in various tissues in both healthy and lipopolysaccharide (LPS)-stimulated specimens, and evaluated its proinflammatory activities. The gcIL-1β gene consists of seven exons and six introns. The full-length cDNA sequence contains an open reading frame of 813 nucleotides. The deduced amino acid sequence exhibits a characteristic IL-1 signature but lacks the typical IL-1β converting enzyme cleavage site that is conserved in mammals. In the phylogenetic tree, IL-1βs from grass carp and other members of the Cyprinidae family clustered into a single group. Expression pattern analysis revealed that gcIL-1β is constitutively expressed in all 11 tissues examined, and LPS stimulation leads to significant up-regulation in muscle, liver, intestine, skin, trunk kidney, head kidney, and gill. Recombinant grass carp IL-1β (rgcIL-1β) was generated prokaryotically as a fusion protein of Trx-rgcIL-1β. An anti-rgcIL-1β polyclonal antibody (rgcIL-1β pAb) was raised in mice against the purified Trx-rgcIL-1β. Western blot analysis confirmed that rgcIL-1β pAb reacted specifically with gcIL-1β in C. idella kidney (CIK) cells. Quantitative real-time PCR data indicated that intestinal mRNA expression levels of endogenous IL-1β, IL-1R2, and TNF-α were significantly up-regulated following Trx-rgcIL-1β exposure. The inhibitory activities of rgcIL-1β pAb against the inflammatory response were confirmed in a model of Aeromonas hydrophila-induced intestinal inflammation. Our immunohistochemical study revealed that the degree and intensity of inflammatory cell infiltration are fully consistent with the observed mRNA expression patterns of these key inflammatory genes. Taken together, these data suggest that gcIL-1β plays a critical role in the proinflammatory response in the grass carp intestine.

Sickness: From the focus on cytokines, prostaglandins, and complement factors to the perspectives of neurons

Systemic inflammation leads to a variety of physiological (e.g. fever) and behavioral (e.g. anorexia, immobility, social withdrawal, depressed mood, disturbed sleep) responses that are collectively known as sickness. While these phenomena have been studied for the past few decades, the neurobiological mechanisms by which sickness occurs remain unclear. In this review, we first revisit how the body senses and responds to infections and injuries by eliciting systemic inflammation. Next, we focus on how peripheral inflammatory molecules such as cytokines, prostaglandins, and activated complement factors communicate with the brain to trigger neuroinflammation and sickness. Since depression also involves inflammation, we further elaborate on the interrelationship between sickness and depression. Finally, we discuss how immune activation can modulate neurons in the brain, and suggest future perspectives to help unravel how changes in neuronal functions relate to sickness responses.

Central mediators involved in the febrile response induced by polyinosinic-polycytidylic acid: lack of involvement of endothelins and substance P

The present study evaluated the involvement of interleukin(IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, interferon(IFN)-γ, prostaglandins of the E2 series, endothelins, substance P and opioids within the central nervous system in polyinosinic:polycytidylic acid (Poly I:C)-induced fever in rats. Poly I:C injection induced a febrile response which was reduced by intracerebroventricular administration of the antibodies against TNF-α, IL-6, or IFN-γ, or by IL-1 or μ receptor antagonists. Intraperitoneal injection of indomethacin or oral administration of celecoxib also reduced Poly I:C-induced fever. Poly I:C increased prostaglandin E2 levels in the cerebrospinal fluid of the animals which was also reduced by indomethacin. The intracerebroventricular injection of ETB or NK1 receptor antagonists did not alter Poly I:C-induced fever. These data suggest the involvement of IL-1β, TNF-α, IL-6, IFN-γ, prostaglandin E2, and opioids but not endothelins and substance P on Poly I:C-induced fever.