Fever and hypothermia in systemic inflammation

Determination of systemic inflammation response index (SIRI), systemic inflammatory index (SII), HMGB1, Mx1 and TNF levels in neonatal calf diarrhea with systemic inflammatory response syndrome

The objective of this study was to examine the values of MX dynamin-like GTPase 1 (Mx1), high mobility group box-1 (HMGB1), systemic inflammatory response index (SIRI), systemic inflammatory index (SII), tumor necrosis factor (TNF), and other hematological indices in calves with systemic inflammatory response syndrome (SIRS). The study material was divided into two groups: the SIRS group (comprising 13 calves) and the control group (comprising 10 calves). The independent samples t-test and Mann-Whitney U test were employed for normally distributed and non-normally distributed data, respectively. The relationship between the two groups was determined using Spearman correlation coefficient analysis. Significant differences were identified between the SIRS group and the control group with regard to white blood cell (WBC; P < 0.05), neutrophil (NEU; P < 0.01), and neutrophil-to-lymphocyte ratio (NLR; P < 0.001) values, in addition to SIRI (P < 0.05), SII (P < 0.01) values. Furthermore, HMGB1 (P < 0.001), Mx1 (P < 0.05), and TNF values (P < 0.001) demonstrated notable disparities between the two groups. As a result of this study, it was concluded that there were significant increases in inflammatory hematological indices, as well as in the levels of HMGB1, Mx1, and TNF, in calves with SIRS.

Temperature trajectories and mortality in hypothermic sepsis patients

OBJECTIVES

Hypothermia is associated with poor outcomes in sepsis patients, and hypothermic sepsis patients exhibit temperature alterations during initial treatment. The objective of this study was to classify hypothermic sepsis patients based on body temperature trajectories and investigate the associations of these patients with 28-day mortality.

METHODS

This was a retrospective analysis of prospectively collected data from adult sepsis or septic shock patients who visited three emergency departments between August 2014 and December 2019. Hypothermic sepsis was defined as an initial body temperature <36 °C. delta temperature was calculated by subtracting the 0 h body temperature from the 6 h body temperature. We divided the patients into three groups according to delta temperature: Group A (delta temperature ≤ 0), Group B (0 < delta temperature ≤ 1) and Group C (delta temperature > 1). The primary outcome was 28-day mortality, and a multivariable Cox proportional hazards regression model was generated.

RESULTS

Among 7344 patients with sepsis or septic shock, 325 hypothermic patients were included in the analysis, and the overall mortality rate was 36%. While initial body temperature was not different between survivors and nonsurvivors, survivors exhibited a higher body temperature at 6 h. The 28-day mortality rates for Groups A, B and C were 53.1%, 36.0%, and 30.0%, respectively, and Group A had significantly higher mortality than Group C did (p < 0.05). Group C demonstrated a 44.2% decrease in 28-day mortality compared to Group A (adjusted hazard ratio of 0.558; 95% confidence interval of 0.330-0.941).

CONCLUSIONS

In hypothermic sepsis patients, an increase of 1 °C or more in body temperature after the initial 6 h is associated with a reduced risk of 28-day mortality.

INTERPLAY BETWEEN BRAIN OXYGENATION AND THE DEVELOPMENT OF HYPOTHERMIA IN ENDOTOXIC SHOCK

ABSTRACT

There is evidence to suggest that the hypothermia observed in the most severe cases of systemic inflammation or sepsis is a regulated response with potential adaptive value, but the mechanisms involved are poorly understood. Here, we investigated the interplay between brain oxygenation (assessed by tissue P o2 ) and the development of hypothermia in unanesthetized rats challenged with a hypotension-inducing dose of bacterial LPS (1 mg/kg i.v.). At an ambient temperature of 22°C, oxygen consumption (V̇O 2 ) began to fall only a few minutes after the LPS injection, and this suppression in metabolic rate preceded the decrease in core temperature. No reduction in brain P o2 was observed prior to the development of the hypometabolic, hypothermic response, ruling out the possibility that brain hypoxia served as a trigger for hypothermia in this model. Brain P o2 was even increased. Such an improvement in brain oxygenation could reflect either an increased O 2 delivery or a decreased O 2 consumption. The former explanation seems unlikely because blood flow (cardiac output) was being progressively decreased during the recording period. On the other hand, the decrease in V̇O 2 usually preceded the rise in P o2 , and an inverse correlation between V̇O 2 and brain P o2 was consistently observed. These findings do not support the existence of a closed-loop feedback relationship between brain oxygenation and hypothermia in systemic inflammation. The data are consistent with a feedforward mechanism in which hypothermia is triggered (possibly by cryogenic inflammatory mediators) in anticipation of changes in brain oxygenation to prevent the development of tissue hypoxia.

Assessing the effects of oxytocin in changes of core body temperature during LPS-induced endotoxemia: A novel approach using Extended Poincaré Plot Analysis

Oxytocin has shown cardioprotective effects during inflammation and may modify the core body temperature changes in LPS-induced endotoxemia. Notably, the time series analysis of core body temperature fluctuations may indicate thermoregulation alterations. This study aims to assess the effects of oxytocin on changes in the core body temperature by analyzing the fluctuations of the temperature time series of endotoxemic rats. Twelve hours of continuous core body temperature fluctuations time series were obtained from adult male Dark Agouti rats implanted with a telemetric transmitter under the following treatment: lipopolysaccharide (LPS); oxytocin (O); lipopolysaccharide + oxytocin (LPS + O), and vehicle or control (C). The temperature fluctuations time series were analyzed using the Extended Poincaré Plot Analysis (EPPA), a novel approach for measuring nonlinear features, to compute the autocorrelation by Pearson's correlation coefficient r, the standard deviation perpendicular to the line of identity (SD1), and the standard deviation parallel to the line of identity (SD2). The autocorrelation of the temperature fluctuations assessed by Pearson's coefficient was significantly higher in the LPS group compared to control rats (C). Likewise, the co-administration of oxytocin during endotoxemia (LPS + O) significantly reduced the autocorrelation and increased the short-term variability (SD1) of temperature fluctuations compared to those recorded with a single dose of LPS. Thus, we concluded that oxytocin may introduce thermoregulatory changes under LPS-induced endotoxemia. The EPPA is a simple and powerful approach to assess physiological variability that can provide valuable insights into changes in thermoregulation.

Encapsulation of Triphasia trifolia extracts by pH and thermal dual-sensitive chitosan hydrogels for controlled release

Recent studies have developed varied delivery systems incorporating natural compounds to improve the limitations of plant extracts for clinical use while enabling their controlled release at treatment sites. For the first time, ethanolic limeberry extract (Triphasia trifolia) has been successfully encapsulated in thermo-sensitive chitosan hydrogels by a facile in situ loading. The extract-incorporated chitosan hydrogels have a pH value of nearly 7.00, gelation temperatures in the range of 37-38 °C, and exhibit an open-cell porous structure, thus allowing them to absorb and retain 756 % of their mass in water. The in vitro extract release from the hydrogels is driven by both temperature and pH, resulting in more than 70 % of the initial extract being released within the first 24 h. Although the release half-life of hydrogels at pH 7.4 is longer, their release capacity is higher than that at pH 6.5. Upon a 2 °C increase in temperature, the time to release 50 % initial extract is sharply reduced by 20-40 %. The release kinetics from the hydrogels mathematically demonstrated that diffusion is a prominent driving force over chitosan relaxation. Consequently, the developed hydrogels encapsulating the limeberry extract show their heat and pH sensitivity in controlled release for treating chronic wounds.

Icilin, a cool/cold-inducing agent, alleviates lipopolysaccharide-induced septic sickness responses in mice

Sepsis is a significant global public health challenge, resulting in millions of human deaths annually. Transient receptor potential melastatin 8 (TRPM8), a non-selective ion channel, is the primary cold sensor in humans; however, its effects on endotoxin-induced inflammation remain unclear. We previously reported that TRPM8 knockout mice exhibited more severe physiological and behavioral endotoxemia responses upon a high-dose injection with lipopolysaccharide (LPS). In the present study, we investigated whether icilin, a TRPM8 agonist, was a target for the suppression of sickness responses using a mouse model of LPS-induced sepsis. A peripheral high-dose injection of LPS at 5 mg/kg showed a maximal body temperature decrease of 5.1 °C in mice subcutaneously pretreated with vehicle and 1.5 °C in icilin-pretreated animals. The decline in locomotor activity was attenuated in icilin-pretreated mice and its recovery was faster; however, the high-dose LPS injection rapidly decreased locomotor activity regardless of the icilin pretreatment. Furthermore, the icilin pretreatment attenuated LPS-induced decreases in body weight and food and water intakes and accelerated recovery from these sickness responses. Therefore, the present results demonstrated that the icilin pretreatment alleviated LPS-induced sickness responses or decreases in body temperature, locomotor activity, body weight loss, and food and water intakes, suggesting its potential as a therapeutic target for sepsis.

Mechanical replication of natural fever enhances protection against Aeromonas veronii infection in a teleost fish

There is a long-standing debate on the attributes of temperature for fish health. We recently showed that thermoregulatory programs exerted through natural behavioural fever drive molecular and cellular responses that contribute to pathogen clearance, inflammation control, and tissue repair. These offered a mechanistic basis for the survival advantage conferred through fever. Herein, we show the attributes of mechanical replication of this fever response. Central to our approach was consideration of both, the maximal temperatures naturally selected by fish after infection, as well as the dynamics of thermal changes induced through this response. Coarse replication of the febrile thermal program as well as shorter truncated thermal schedules offered immune-regulatory capacity. Most notably, these promoted induction of acute inflammation and significant enhancements to pathogen clearance. However, the coarse protocols tested only partially recapitulated enhancements to induction and control of tissue repair. Our findings highlight a promising new alternative to combat infections in fish using a natural, drug-free, sustainable approach.

Neurogenic Fever after Subarachnoid Hemorrhage in Animal Models: A Systematic Review

The observation of neurogenic fever resulting from subarachnoid hemorrhage (SAH) in animal models is a useful tool for the interpretation of its pathophysiology in humans, which is still a major challenge in the management of neurocritical patients. This systematic review aims to identify the prognostic factors and pathophysiological elements that determine the onset of neurogenic fever and its severity in animal models. In addition, our study aims to analyze which pharmacological treatments are most effective. All the articles available in Pubmed, Embase, and the Biological Science Collection until August 2021 concerning in vivo experimental studies on SAH animal models, including full texts and abstracts written in English and Italian, were considered. The risk of bias was assessed with SYRCLE's Risk of Bias tool. In total, 81 records were retrieved; after excluding duplicates, 76 records were potentially relevant. A total of 64 articles was excluded after title and abstract screening. The remaining 12 studies were evaluated as full texts, and 6 other studies were excluded (SAH-induced animal studies without a body temperature assessment). In one study, body temperature was measured after SAH induction, but the authors did not report temperature recording. Therefore, only five studies met the search criteria. The high methodological heterogeneity (different animal species, different temperature measurement methods, and different methods of the induction of bleeding) prevented meta-analysis. Synthesis methodology without meta-analysis (SWiM) was used for data analysis. The total number of animals used as controls was 87 (23 rabbits, 32 mice, and 32 rats), while there were 130 animals used as interventions (54 rabbits, 44 mice, and 32 rats). The presence of blood in the subarachnoid space, particularly red blood cells, is responsible for neurogenic fever; the role of hemoglobin is unclear. The mechanism is apparently not mediated by prostaglandins. The autonomic nervous system innervating brown adipose tissue is undoubtedly implicated in the onset of neurogenic fever. The activation of the central adenosine-1 receptor is effective in controlling the temperature of animals with neurogenic fever (by inhibiting thermogenesis of brown adipose tissue).

Escherichia coli-induced inflammatory responses are temperature-dependent in human whole blood ex vivo

Systemic inflammatory conditions are often associated with hypothermia or hyperthermia. Therapeutic hypothermia is used in post-cardiac arrest and some other acute diseases. There is a need for more knowledge concerning the effect of various temperatures on the acute inflammatory response. The complement system plays a crucial role in initiating the inflammatory response. We hypothesized that temperatures above and below the physiologic 37 °C affect complement activation and cytokine production ex vivo. Lepirudin-anticoagulated human whole blood from 10 healthy donors was incubated in the presence or absence of Escherichia coli at different temperatures (4 °C, 12 °C, 20 °C, 33 °C, 37 °C, 39 °C, and 41 °C). Complement activation was assessed by the terminal C5b-9 complement complex (TCC) and the alternative convertase C3bBbP using ELISA. Cytokines were measured using a 27-plex assay. Granulocyte and monocyte activation was evaluated by CD11b surface expression using flow cytometry. A consistent increase in complement activation was observed with rising temperature, reaching a maximum at 41 °C, both in the absence (C3bBbP p < 0.05) and presence (C3bBbP p < 0.05 and TCC p < 0.05) of E. coli. Temperature alone did not affect cytokine production, whereas incubation with E. coli significantly increased cytokine levels of IL-1β, IL-2, IL-6, IL-8, IFN-γ, and TNF at temperatures > 20 °C. Maximum increase occurred at 39 °C. However, a consistent decrease was observed at 41 °C, significant for IL-1β (p = 0.003). Granulocyte CD11b displayed the same temperature-dependent pattern as cytokines, with a corresponding increase in endothelial cell apoptosis and necrosis. Thus, blood temperature differentially determines the degree of complement activation and cytokine release.

Hypothermia or hyperthermia, which is associated with patient outcomes in critically ill children with sepsis? -A retrospective study

OBJECTIVES

In the early stage of sepsis, identifying high-risk paediatric patients with a poor prognosis and providing timely and adequate treatment are critical. This study aimed to evaluate the effect of average body temperature within 24 hours of admission on the short-term prognosis of paediatric patients with sepsis.

DESIGN

A retrospective cohort study.

SETTING

A single-centre, tertiary care hospital in China, containing patient data from 2010 to 2018.

PARTICIPANTS

1144 patients with sepsis were included.

INTERVENTION

None.

PRIMARY AND SECONDARY OUTCOME MEASURES

The main outcome measure was in-hospital mortality, which was defined as death from any cause during hospitalisation. The secondary outcome was the length of hospital stay.

RESULTS

The LOWESS method showed a roughly 'U'-shaped relationship between body temperature on the first day and in-hospital mortality. Multivariate logistic regression showed that severe hypothermia (OR 14.72, 95% CI 4.84 to 44.75), mild hypothermia (OR 3.71, 95% CI 1.26 to 10.90), mild hyperthermia (OR 3.41, 95% CI 1.17 to 9.90) and severe hyperthermia (OR 5.15, 95% CI 1.84 to 14.43) were independent risk factors for in-hospital mortality. Compared with other variables, the Wald χ² value of temperature on the first day minus the degree of freedom was the highest.

CONCLUSIONS

Whether hypothermic or hyperthermic, the more abnormal the temperature on the first day is, the higher the risk of in-hospital death in children with sepsis.

Fever integrates antimicrobial defences, inflammation control, and tissue repair in a cold-blooded vertebrate

Multiple lines of evidence support the value of moderate fever to host survival, but the mechanisms involved remain unclear. This is difficult to establish in warm-blooded animal models, given the strict programmes controlling core body temperature and the physiological stress that results from their disruption. Thus, we took advantage of a cold-blooded teleost fish that offered natural kinetics for the induction and regulation of fever and a broad range of tolerated temperatures. A custom swim chamber, coupled to high-fidelity quantitative positional tracking, showed remarkable consistency in fish behaviours and defined the febrile window. Animals exerting fever engaged pyrogenic cytokine gene programmes in the central nervous system, increased efficiency of leukocyte recruitment into the immune challenge site, and markedly improved pathogen clearance in vivo, even when an infecting bacterium grew better at higher temperatures. Contrary to earlier speculations for global upregulation of immunity, we identified selectivity in the protective immune mechanisms activated through fever. Fever then inhibited inflammation and markedly improved wound repair. Artificial mechanical hyperthermia, often used as a model of fever, recapitulated some but not all benefits achieved through natural host-driven dynamic thermoregulation. Together, our results define fever as an integrative host response that regulates induction and resolution of acute inflammation, and demonstrate that this integrative strategy emerged prior to endothermy during evolution.

Temperature threshold in the screening of bacterial infections in young infants with hypothermia

BACKGROUND

Young infants with hypothermia presenting to the emergency department (ED) are at risk for serious bacterial infections (SBI), however there is no consensus temperature to prompt evaluation for SBI among these children. We sought to statistically derive a temperature threshold to guide detection of SBI in young infants with hypothermia presenting to the ED.

METHODS

We performed a cross-sectional study of infants ≤90 days old presenting to four academic paediatric EDs in the United States of America from January 2015 through December 2019 with a rectal temperature of ≤36.4°C. Our primary outcomes were SBI, defined as urinary tract infection (UTI), bacteraemia and/or bacterial meningitis, and invasive bacterial infections (IBI, limited to bacteraemia and/or bacterial meningitis). We constructed receiver operating characteristic (ROC) curves to evaluate an optimally derived cutpoint for minimum ED temperature and presence of SBI or IBI.

RESULTS

We included 3376 infants, of whom SBI were found in 62 (1.8%) and IBI in 16 (0.5%). The most common infection identified was Escherichia coli UTI. Overall, cohort minimum median temperature was 36.2°C (IQR 36.0°C-36.4°C). Patients with SBI and IBI had lower median temperatures, 35.8°C (IQR 35.8°C-36.3°C) and 35.4°C (IQR 35.7°C-36.3°C), respectively, compared with those without corresponding infections (both p<0.05). Using an outcome of SBI, the area under the ROC curve (AUROC) was 61.0% (95% CI 54.1% to 67.9%). At a cutpoint of 36.2°C, sensitivity was 59.7% and specificity was 59.2%. When using an outcome of IBI, the AUROC was 65.9% (95% CI 51.1% to 80.6%). Using a cutpoint of 36.1°C in this model resulted in a sensitivity of 68.8% and specificity of 60.1%.

CONCLUSION

Young infants with SBI and IBI presented with lower temperatures than infants without infections. However, there was no temperature threshold to reliably identify SBI or IBI. Further research incorporating clinical and laboratory parameters, in addition to temperature, may help to improve risk stratification for these vulnerable patients.

Plasma Cyclooxygenase-2 as a Potential Biomarker for Early Diagnosis of Kawasaki Disease

Background: Previous research demonstrated the association between cyclooxygenase-2 (COX-2) gene polymorphisms and susceptibility to Kawasaki disease (KD). This study aims to detect the plasma concentration of COX-2 in different phases of KD patients and evaluate the relationship between COX-2 level and coronary artery lesion formation, therapeutic response to intravenous immunoglobulin. Methods: Plasma COX-2 levels were measured by enzyme-linked immunosorbent assay in KD patients during the acute (a-KD, n = 52), subacute (s-KD, n = 46), and convalescent (c-KD, n = 43) phase. Results: The concentration of COX-2 in the a-KD group was significantly higher than that in the s-KD, c-KD, healthy control or febrile control group, respectively. There was no difference in the levels of COX-2 between the KD with or without coronary artery lesion subgroups, intravenous immunoglobulin resistant, and sensitive subgroups in the a-KD group, respectively. Conclusions: The plasma concentration of COX-2 might be a novel potential biomarker of acute KD.

Inhibition of nitric oxide synthase or cystathionine gamma-lyase abolishes leptin-induced fever in male rats

Leptin is an adipokine that regulates energy balance and immune function. Peripheral leptin administration elicits prostaglandin E₂-dependent fever in rats. The gasotransmitters nitric oxide (NO) and hydrogen sulfide (H₂S) are also involved in lipopolysaccharide (LPS)-induced fever response. However, there is no data in the literature indicating if these gasotransmitters have a role in leptin-induced fever response. Here, we investigate the inhibition of NO and H₂S enzymes neuronal nitric oxide synthase (nNOS), inducible nitric oxide synthase (iNOS), and cystathionine γ-lyase (CSE) in leptin-induced fever response, respectively. Selective nNOS inhibitor 7-nitroindazole (7-NI), selective iNOS inhibitor aminoguanidine (AG), and CSE inhibitor dl-propargylglycine (PAG) were administered intraperitoneally (ip). Body temperature (Tb), food intake, and body mass were recorded in fasted male rats. Leptin (0.5 mg/kg ip) induced a significant increase in Tb, whereas AG (50 mg/kg ip), 7-NI (10 mg/kg ip), or PAG (50 mg/kg ip) caused no changes in Tb. AG, 7-NI, or PAG abolished leptin increase in Tb. Our results highlight the potential involvement of iNOS, nNOS, and CSE in leptin-induced febrile response without affecting anorexic response to leptin in fasted male rats 24 h after leptin injection. Interestingly, all the inhibitors alone had the same anorexic effect induced by leptin. These findings have implications for understanding the role of NO and H₂S in leptin-induced febrile response.

Systemic Lipopolysaccharide Challenge Induces Inflammatory Changes in Rat Dorsal Root Ganglia: An Ex Vivo Study

Inflammatory processes within the peripheral nervous system (PNS) are associated with symptoms of hyperalgesia and allodynia. Pro-inflammatory mediators, such as cytokines or prostaglandins, modulate the excitability of nociceptive neurons, called peripheral sensitization. Here, we aimed to examine if previously reported effects of in vitro stimulation with lipopolysaccharide (LPS) on primary cell cultures of dorsal root ganglia (DRG) reflect changes in a model of LPS-induced systemic inflammation in vivo. Male rats were intraperitoneally injected with LPS (100 µg/kg) or saline. Effects of systemic inflammation on expression of inflammatory mediators, neuronal Ca2+ responses, and activation of inflammatory transcription factors in DRG were assessed. Systemic inflammation was accompanied by an enhanced expression of pro-inflammatory cytokines and cyclooxygenase-2 in lumbar DRG. In DRG primary cultures obtained from LPS-treated rats enhanced neuronal capsaicin-responses were detectable. Moreover, we found an increased activation of inflammatory transcription factors in cultured macrophages and neurons after an in vivo LPS challenge compared to saline controls. Overall, our study emphasizes the role of inflammatory processes in the PNS that may be involved in sickness-behavior-associated hyperalgesia induced by systemic LPS treatment. Moreover, we present DRG primary cultures as tools to study inflammatory processes on a cellular level, not only in vitro but also ex vivo.

Effects of peripheral administration of lipopolysaccharide on chronic sickness responses in TRPM8-deficient mice

Transient receptor potential melastatin 8 (TRPM8) is a cold-sensing thermoreceptor cation channel; however, its functional role in endotoxin-induced neuroinflammation remains unclear. In the present study, we investigated chronic sickness responses in TRPM8 knockout (KO) mice during lipopolysaccharide (LPS)-induced sepsis. The intraperitoneal administration of 5 mg/kg LPS generated longer-lasting hypothermia in TRPM8 KO mice than in wild-type (WT) mice. TRPM8 KO mice also exhibited longer-lasting declines in locomotor activity, body weight, and food and water intakes than WT mice upon LPS administration. In addition, LPS-induced decreases in the numbers of leucocytes and lymphocytes that persisted for a longer time in TRPM8 KO mice than in WT mice. The present results indicate TRPM8 attenuated chronic sickness responses in endotoxin-induced sepsis.

Browning of the white adipose tissue regulation: new insights into nutritional and metabolic relevance in health and diseases

Adipose tissues are dynamic tissues that play crucial physiological roles in maintaining health and homeostasis. Although white adipose tissue and brown adipose tissue are currently considered key endocrine organs, they differ functionally and morphologically. The existence of the beige or brite adipocytes, cells displaying intermediary characteristics between white and brown adipocytes, illustrates the plastic nature of the adipose tissue. These cells are generated through white adipose tissue browning, a process associated with augmented non-shivering thermogenesis and metabolic capacity. This process involves the upregulation of the uncoupling protein 1, a molecule that uncouples the respiratory chain from Adenosine triphosphate synthesis, producing heat. β-3 adrenergic receptor system is one important mediator of white adipose tissue browning, during cold exposure. Surprisingly, hyperthermia may also induce beige activation and white adipose tissue beiging. Physical exercising copes with increased levels of specific molecules, including Beta-Aminoisobutyric acid, irisin, and Fibroblast growth factor 21 (FGF21), which induce adipose tissue browning. FGF21 is a stress-responsive hormone that interacts with beta-klotho. The central roles played by hormones in the browning process highlight the relevance of the individual lifestyle, including circadian rhythm and diet. Circadian rhythm involves the sleep-wake cycle and is regulated by melatonin, a hormone associated with UCP1 level upregulation. In contrast to the pro-inflammatory and adipose tissue disrupting effects of the western diet, specific food items, including capsaicin and n-3 polyunsaturated fatty acids, and dietary interventions such as calorie restriction and intermittent fasting, favor white adipose tissue browning and metabolic efficiency. The intestinal microbiome has also been pictured as a key factor in regulating white tissue browning, as it modulates bile acid levels, important molecules for the thermogenic program activation. During embryogenesis, in which adipose tissue formation is affected by Bone morphogenetic proteins that regulate gene expression, the stimuli herein discussed influence an orchestra of gene expression regulators, including a plethora of transcription factors, and chromatin remodeling enzymes, and non-coding RNAs. Considering the detrimental effects of adipose tissue browning and the disparities between adipose tissue characteristics in mice and humans, further efforts will benefit a better understanding of adipose tissue plasticity biology and its applicability to managing the overwhelming burden of several chronic diseases.

Prostanoid Metabolites as Biomarkers in Human Disease

Prostaglandins (PGD₂, PGE₂, PGF_2α), prostacyclin (PGI₂), and thromboxane A₂ (TXA₂) together form the prostanoid family of lipid mediators. As autacoids, these five primary prostanoids propagate intercellular signals and are involved in many physiological processes. Furthermore, alterations in their biosynthesis accompany a wide range of pathological conditions, which leads to substantially increased local levels during disease. Primary prostanoids are chemically instable and rapidly metabolized. Their metabolites are more stable, integrate the local production on a systemic level, and their analysis in various biological matrices yields valuable information under different pathological settings. Therefore, prostanoid metabolites may be used as diagnostic, predictive, or prognostic biomarkers in human disease. Although their potential as biomarkers is great and extensive research has identified major prostanoid metabolites that serve as target analytes in different biofluids, the number of studies that correlate prostanoid metabolite levels to disease outcome is still limited. We review the metabolism of primary prostanoids in humans, summarize the levels of prostanoid metabolites in healthy subjects, and highlight existing biomarker studies. Since analysis of prostanoid metabolites is challenging because of ongoing metabolism and limited half-lives, an emphasis of this review lies on the reliable measurement and interpretation of obtained levels.

Prenylation Defects and Oxidative Stress Trigger the Main Consequences of Neuroinflammation Linked to Mevalonate Pathway Deregulation

The cholesterol biosynthesis represents a crucial metabolic pathway for cellular homeostasis. The end products of this pathway are sterols, such as cholesterol, which are essential components of cell membranes, precursors of steroid hormones, bile acids, and other molecules such as ubiquinone. Furthermore, some intermediates of this metabolic system perform biological activity in specific cellular compartments, such as isoprenoid molecules that can modulate different signal proteins through the prenylation process. The defects of prenylation represent one of the main causes that promote the activation of inflammation. In particular, this mechanism, in association with oxidative stress, induces a dysfunction of the mitochondrial activity. The purpose of this review is to describe the pleiotropic role of prenylation in neuroinflammation and to highlight the consequence of the defects of prenylation.

Neural circuits mediating circulating interleukin-1β-evoked fever in the absence of prostaglandin E2 production

Infectious diseases and inflammatory conditions recruit the immune system to mount an appropriate acute response that includes the production of cytokines. Cytokines evoke neurally-mediated responses to fight pathogens, such as the recruitment of thermoeffectors, thereby increasing body temperature and leading to fever. Studies suggest that the cytokine interleukin-1β (IL-1β) depends upon cyclooxygenase (COX)-mediated prostaglandin E₂ production for the induction of neural mechanisms to elicit fever. However, COX inhibitors do not eliminate IL-1β-induced fever, thus suggesting that COX-dependent and COX-independent mechanisms are recruited for increasing body temperature after peripheral administration of IL-1β. In the present study, we aimed to build a foundation for the neural circuit(s) controlling COX-independent, inflammatory fever by determining the involvement of brain areas that are critical for controlling the sympathetic outflow to brown adipose tissue (BAT) and the cutaneous vasculature. In anesthetized rats, pretreatment with indomethacin, a non-selective COX inhibitor, did not prevent BAT thermogenesis or cutaneous vasoconstriction (CVC) induced by intravenous IL-1β (2 µg/kg). BAT and cutaneous vasculature sympathetic premotor neurons in the rostral raphe pallidus area (rRPa) are required for IL-1β-evoked BAT thermogenesis and CVC, with or without pretreatment with indomethacin. Additionally, activation of glutamate receptors in the dorsomedial hypothalamus (DMH) is required for COX-independent, IL-1β-induced BAT thermogenesis. Therefore, our data suggests that COX-independent mechanisms elicit activation of neurons within the DMH and rRPa, which is sufficient to trigger and mount inflammatory fever. These data provide a foundation for elucidating the brain circuits responsible for COX-independent, IL-1β-elicited fevers.

Curcumin attenuates LPS-induced sickness behavior and fever in rats by modulating Nrf2 activity

Lipopolysaccharide (LPS) is a potent inducer of inflammation, triggering behavioral changes and fever. The present study aimed to evaluate whether pretreatment with curcumin prevents the behavioral changes and fever induced by LPS through the modulation of nuclear factor-erythroid 2 related factor 2 (Nrf2). Male Wistar rats received either vehicle or LPS and after 2 h, the behavioral responses were assessed through open field test (OFT), social interaction test, forced swim test (FST), and food intake assessment. The febrile response was assessed by telemetry after vehicle or LPS injection to evaluate the effect of curcumin on the thermoregulatory response during the immunological challenge. The pretreatment with curcumin at doses of 50 and 100 mg/kg prevented the reduction of distance traveled on OFT, increased the immobility time of FST, impaired social withdrawal, decreased food intake, and induced fever. In addition, at these doses, it was possible to observe a significant decrease in the plasma levels of cytokines and an increase in Nrf2 translocation to the cell nucleus during the immunological challenge. Our data provide further evidence of curcumin's ability to prevent LPS-induced sickness behavior and fever possibly by a mechanism related to the modulation of Nrf2 translocation.

Reliable and Remote Monitoring of Absolute Temperature during Liver Inflammation via Luminescence-Lifetime-Based Nanothermometry

Temperature of tissues and organs is one of the first parameters affected by physiological and pathological processes, such as metabolic activity, acute trauma, or infection-induced inflammation. Therefore, the onset and development of these processes can be detected by monitoring deviations from basal temperature. To accomplish this, minimally invasive, reliable, and accurate measurement of the absolute temperature of internal organs is required. Luminescence nanothermometry is the ideal technology for meeting these requirements. Although this technique has lately undergone remarkable developments, its reliability is being questioned due to spectral distortions caused by biological tissues. In this work, how the use of bright Ag₂ S nanoparticles featuring temperature-dependent fluorescence lifetime enables reliable and accurate measurement of the absolute temperature of the liver in mice subjected to lipopolysaccharide-induced inflammation is demonstrated. Beyond the remarkable thermal sensitivity (≈ 3% °C^-1 around 37 °C) and thermal resolution obtained (smaller than 0.3 °C), the results included in this work set a blueprint for the development of new diagnostic procedures based on the use of intracorporeal temperature as a physiological indicator.

Changes in Body Surface Temperature Play an Underappreciated Role in the Avian Immune Response

AbstractFever and hypothermia are well-characterized components of systemic inflammation. However, our knowledge of the mechanisms underlying such changes in body temperature is largely limited to rodent models and other mammalian species. In mammals, high dosages of an inflammatory agent (e.g., lipopolysaccharide [LPS]) typically leads to hypothermia (decrease in body temperature below normothermic levels), which is largely driven by a reduction in thermogenesis and not changes in peripheral vasomotion (i.e., changes in blood vessel tone). In birds, however, hypothermia occurs frequently, even at lower dosages, but the thermoeffector mechanisms associated with the response remain unknown. We immune challenged zebra finches (Taeniopygia guttata) with LPS, monitored changes in subcutaneous temperature and energy balance (i.e., body mass, food intake), and assessed surface temperatures of and heat loss across the eye region, bill, and legs. We hypothesized that if birds employ thermoregulatory mechanisms similar to those of similarly sized mammals, LPS-injected individuals would reduce subcutaneous body temperature and maintain constant surface temperatures compared with saline-injected individuals. Instead, LPS-injected individuals showed a slight elevation in body temperature, and this response coincided with a reduction in peripheral heat loss, particularly across the legs, as opposed to changes in energy balance. However, we note that our interpretations should be taken with caution owing to small sample sizes within each treatment. We suggest that peripheral vasomotion, allowing for heat retention, is an underappreciated component of the sickness-induced thermoregulatory response of small birds.

ACE2 is the critical in vivo receptor for SARS-CoV-2 in a novel COVID-19 mouse model with TNF- and IFNγ-driven immunopathology

Despite tremendous progress in the understanding of COVID-19, mechanistic insight into immunological, disease-driving factors remains limited. We generated maVie16, a mouse-adapted SARS-CoV-2, by serial passaging of a human isolate. In silico modeling revealed how only three Spike mutations of maVie16 enhanced interaction with murine ACE2. maVie16 induced profound pathology in BALB/c and C57BL/6 mice, and the resulting mouse COVID-19 (mCOVID-19) replicated critical aspects of human disease, including early lymphopenia, pulmonary immune cell infiltration, pneumonia, and specific adaptive immunity. Inhibition of the proinflammatory cytokines IFNγ and TNF substantially reduced immunopathology. Importantly, genetic ACE2-deficiency completely prevented mCOVID-19 development. Finally, inhalation therapy with recombinant ACE2 fully protected mice from mCOVID-19, revealing a novel and efficient treatment. Thus, we here present maVie16 as a new tool to model COVID-19 for the discovery of new therapies and show that disease severity is determined by cytokine-driven immunopathology and critically dependent on ACE2 in vivo.

Genetic identification of preoptic neurons that regulate body temperature in mice

There has been an explosion recently in our understanding of the neuronal populations in the preoptic area involved in thermoregulation of mice. Recent studies have identified several genetically specified populations of neurons predominantly in the median preoptic nucleus (MnPO) but spreading caudolaterally into the preoptic area that regulate body temperature. . These include warm-responsive neurons that express the peptides PACAP, BDNF, or QRFP; and receptors for temperature, leptin, estrogen, or prostaglandin E2 (PGE2). These neurons are predominantly glutamatergic and driving them opto- or chemogenetically can cause profound hypothermia, and in some cases, periods of torpor or a hibernation-like state. Conversely, fever response is likely to depend upon inhibiting the activity of these neurons through the PGE2 receptor EP3. Another cell group, the Brs3-expressing MnPO neurons, are apparently cold-responsive and cause increases in body temperature. MnPO-QRFP neurons cause hypothermia via activation of their terminals in the region of the dorsomedial nucleus of the hypothalamus (DMH). As the MnPO-QRFP neurons are essentially glutamatergic, and the DMH largely uses glutamatergic projections to the raphe pallidus to increase body temperature, this model suggests the existence of local inhibitory interneurons in the DMH region between the MnPO-QRFP glutamatergic neurons that cause hypothermia and the DMH glutamatergic neurons that cause hyperthermia. The new genetically targeted studies in mice provide a way to identify the precise neuronal circuitry that is responsible for our physiological observations in this species, and will suggest critical experiments that can be undertaken to compare these with the thermoregulatory circuitry in other species.

Vital signs as physiomarkers of neonatal sepsis

Neonatal sepsis accounts for significant morbidity and mortality, particularly among premature infants in the Neonatal Intensive Care Unit. Abnormal vital sign patterns serve as physiomarkers of sepsis and provide early warning of illness before overt clinical decompensation. The systemic inflammatory response to pathogens signals the autonomic nervous system, leading to changes in temperature, respiratory rate, heart rate, and blood pressure. In infants with comorbidities of prematurity, vital sign abnormalities often occur in the absence of infection, which confounds sepsis diagnosis. This review will cover the mechanisms of vital sign changes in neonatal sepsis, including the cholinergic anti-inflammatory pathway mediated by the vagus nerve, which is critical to the host response to infectious and inflammatory insults. We will also review the clinical implications of vital sign changes in neonatal sepsis, including their use in early warning scores and systems to direct clinicians to the bedside of infants with physiologic changes that might be due to sepsis. IMPACT: This manuscript summarizes and reviews the relevant literature on the physiological manifestations of neonatal sepsis and how we monitor and analyze these through vital signs and advanced analytics.

The hyperthermic effect of central cholecystokinin is mediated by the cyclooxygenase-2 pathway

Cholecystokinin (CCK) increases core body temperature via CCK₂ receptors when administered intracerebroventricularly (icv). The mechanisms of CCK-induced hyperthermia are unknown, and it is also unknown whether CCK contributes to the fever response to systemic inflammation. We studied the interaction between central CCK signaling and the cyclooxygenase (COX) pathway. Body temperature was measured in adult male Wistar rats pretreated with intraperitoneal infusion of the nonselective COX enzyme inhibitor metamizol (120 mg/kg) or a selective COX-2 inhibitor, meloxicam, or etoricoxib (10 mg/kg for both) and, 30 min later, treated with intracerebroventricular CCK (1.7 µg/kg). In separate experiments, CCK-induced neuronal activation (with and without COX inhibition) was studied in thermoregulation- and feeding-related nuclei with c-Fos immunohistochemistry. CCK increased body temperature by ∼0.4°C from 10 min postinfusion, which was attenuated by metamizol. CCK reduced the number of c-Fos-positive cells in the median preoptic area (by ∼70%) but increased it in the dorsal hypothalamic area and in the rostral raphe pallidus (by ∼50% in both); all these changes were completely blocked with metamizol. In contrast, CCK-induced satiety and neuronal activation in the ventromedial hypothalamus were not influenced by metamizol. CCK-induced hyperthermia was also completely blocked with both selective COX-2 inhibitors studied. Finally, the CCK₂ receptor antagonist YM022 (10 µg/kg icv) attenuated the late phases of fever induced by bacterial lipopolysaccharide (10 µg/kg; intravenously). We conclude that centrally administered CCK causes hyperthermia through changes in the activity of "classical" thermoeffector pathways and that the activation of COX-2 is required for the development of this response.NEW & NOTEWORTHY An association between central cholecystokinin signaling and the cyclooxygenase-prostaglandin E pathway has been proposed but remained poorly understood. We show that the hyperthermic response to the central administration of cholecystokinin alters the neuronal activity within efferent thermoeffector pathways and that these effects are fully blocked by the inhibition of cyclooxygenase. We also show that the activation of cyclooxygenase-2 is required for the hyperthermic effect of cholecystokinin and that cholecystokinin is a modulator of endotoxin-induced fever.

Circadian Rhythms in Bacterial Sepsis Pathology: What We Know and What We Should Know

Sepsis is a syndrome caused by a deregulated host response to infection, representing the primary cause of death from infection. In animal models, the mortality rate is strongly dependent on the time of sepsis induction, suggesting a main role of the circadian system. In patients undergoing sepsis, deregulated circadian rhythms have also been reported. Here we review data related to the timing of sepsis induction to further understand the different outcomes observed both in patients and in animal models. The magnitude of immune activation as well as the hypothermic response correlated with the time of the worst prognosis. The different outcomes seem to be dependent on the expression of the clock gene Bmal1 in the liver and in myeloid immune cells. The understanding of the role of the circadian system in sepsis pathology could be an important tool to improve patient therapies.

Tetralone derivatives are MIF tautomerase inhibitors and attenuate macrophage activation and amplify the hypothermic response in endotoxemic mice

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine playing crucial role in immunity. MIF exerts a unique tautomerase enzymatic activity that has relevance concerning its multiple functions and its small molecule inhibitors have been proven to block its pro-inflammatory effects. Here we demonstrate that some of the E-2-arylmethylene-1-tetralones and their heteroanalogues efficiently bind to MIF's active site and inhibit MIF tautomeric (enolase, ketolase activity) functions. A small set of the synthesised derivatives, namely compounds (4), (23), (24), (26) and (32), reduced inflammatory macrophage activation. Two of the selected compounds (24) and (26), however, markedly inhibited ROS and nitrite production, NF-κB activation, TNF-α, IL-6 and CCL-2 cytokine expression. Pre-treatment of mice with compound (24) exaggerated the hypothermic response to high dose of bacterial endotoxin. Our experiments suggest that tetralones and their derivatives inhibit MIF's tautomeric functions and regulate macrophage activation and thermal changes in severe forms of systemic inflammation.

Contribution of oxidative stress in the mechanisms of postoperative complications and multiple organ dysfunction syndrome

BACKGROUND

The extent of the damage following surgery has been subject of study for several years. Numerous surgical complications can impact postoperative quality of life of patients and even can cause mortality. Although these complications are generally due to multifactorial mechanisms, oxidative stress plays a key pathophysiological role. Moreover, oxidative stress could be an unavoidable effect derived even from the surgical procedure itself.

METHODS

A systematic review was performed following an electronic search of Pubmed and ScienceDirect databases. Keywords such as sepsis, oxidative stress, organ dysfunction, antioxidants, outcomes in postoperative complications, among others, were used. Review articles were preferably used between the years 2015 onwards, not excluding older ones.

RESULTS

The vast majority point to the role of oxidative stress in generating greater damage and worse prognosis in postoperative patients without the necessary care and precautions, taking importance on the use of antioxidants to prevent this problem.

DISCUSSIONS

Oxidative stress represents a common final pathway related to pathological processes such as inflammation or ischemia-reperfusion, among others. The expression of greater severity of these complications can result in multiple organ dysfunction or sepsis. The aim of this study was to present an update of the role of oxidative stress on surgical postoperative complications.

Pseudocedrela kotschyi: a review of ethnomedicinal uses, pharmacology and phytochemistry

CONTEXT

Pseudocedrela kotschyi (Schweinf) Harms (Meliaceae) is an important medicinal plant found in tropical and subtropical countries of Africa. Traditionally, P. kotschyi is used in the treatment of various diseases including diabetes, malaria, abdominal pain and diarrhoea.

OBJECTIVE

To provide an overview of traditional medicinal claims, pharmacological properties, and phytochemical principles of P. kotschyi as a basis for its clinical applications and further research and development of new drugs.

METHODS

Through interpreting already published scientific manuscripts retrieved from different scientific search engines, namely, Medline, PubMed, EMBASE, Science Direct and Google scholar databases, an up-to-date review on the medicinal potentials of P. kotschyi from inception until September, 2020 was compiled. 'Pseudocedrela kotschyi', 'traditional uses', 'pharmacological properties' and 'chemical constituents' were used as search words.

RESULTS

At present, more than 30 chemical constituents have been isolated and identified from the root and stem bark of P. kotschyi, among which limonoids and triterpenes are the main active constituents. Based on prior research, P. kotschyi has been reported to possess anti-inflammatory, analgesic, antipyretic, anthelminthic, antimalaria, anti-leishmaniasis, anti-trypanosomiasis, hepatoprotective, antioxidant, antidiabetic, antidiarrheal, antimicrobial, and anticancer effects.

CONCLUSIONS

P. kotschyi is reported to be effective in treating a variety of diseases. Current phytochemical and pharmacological studies mainly focus on antimalaria, anti-leishmaniasis, anti-trypanosomiasis and anticancer potential of the root and stem bark of P. kotschyi. Although experimental data support the beneficial medicinal properties of this plant, there is still a paucity of information on its toxicity profile. Nonetheless, this review provides the basis for future research work.

Macrophages Are the Key Players in Promoting Hyper-Inflammatory Response in a Mouse Model of TB-IRIS

TB-IRIS is an abnormal inflammatory response in a subset of HIV-TB co-infected patients shortly after initiation of anti-retroviral therapy (ART). Therapy in these patients could have greatly improved the life expectancy as ART reconstitutes the function and number of CD4+ T cells and many patients see improvement in symptoms but paradoxically up to 54% of co-infected patients develop TB-IRIS. Different studies have indicated that both innate and adaptive immunity are involved in the pathology of IRIS but the role of macrophages in abnormal activation of CD4+ T cells is poorly understood. Since macrophages are one of the major antigen-presenting cells and are infected by M.tb at a high frequency, they are very much likely to be involved in the development of TB-IRIS. In this study, we have developed a mouse model of experimental IRIS, in which M.tb-infected T-cell knockout mice undergo a fatal inflammatory disease after CD4+ T cell reconstitution. Lung macrophages and blood monocytes from M.tb-infected TCRβ-/- mice showed upregulated expression of cell surface activation markers and also showed higher mRNA expression of inflammation-associated chemokines and matrix metalloproteases responsible for tissue damage. Furthermore, cytokine and TLR signaling feedback mechanism to control excessive inflammation was also found to be dysregulated in these macrophages under lymphopenic conditions. Previous studies have shown that hyperactive CD4+ T cells are responsible for disease induction and our study shows that somehow macrophages are in a higher activated state when infected with M.tb in an immune-deficient condition, which results in excessive activation of the adoptively transferred CD4+ T cells. Understanding of the mechanisms underlying the pathophysiology of TB-IRIS would facilitate identification of prospective biomarkers for disease development in HIV-TB co-infected patients before starting antiretroviral therapy.

Recombinant human growth hormone improves the immune status of rats with septic encephalopathy: The role of VEGFR2 in the prevalence of endoplasmic reticulum stress repair module

Septic encephalopathy results from the intense reaction of the immune system to infection. The role of growth hormone (GH) signaling in maintaining brain function is well established; however, the involvement of the vascular endothelial growth factor receptor-2 (VEGFR2) in the potential modulatory effect of GH on septic encephalopathy-associated endoplasmic reticulum stress (ERS) and blood-brain barrier (BBB) permeability is not well-understood. Therefore, after the induction of mid-grade sepsis by cecal ligation/perforation, rats were subcutaneously injected with recombinant human GH (rhGH)/somatropin alone or preceded by the VEGFR2 antagonist WAG-4S for 7 days. rhGH/somatropin reduced bodyweight loss and plasma endotoxin, maintained the hyperthermic state, and improved motor/memory functions. Additionally, rhGH/somatropin increased the junctional E-cadherin and β-catenin pool in the cerebral cortex to enhance the BBB competency, effects that were abolished by VEGFR2 blockade. Also, it activated cortical VEGFR2/mammalian target of the Rapamycin (mTOR) axis to mitigate ERS. The latter was reflected by the deactivation of the inositol-requiring enzyme-1α (IRE1α)/spliced X-box binding protein-1 (XBP1s) trajectory and the reduction in the protein levels of the death markers, C/EBP homologous protein (CHOP)/growth arrest and DNA damage-153 (GADD153), c-jun-N-terminal kinase (JNK), and caspase-3 with the simultaneous augmentation of expression of the unfolded protein response transducer proteinkinaseR-like ERkinase (PERK). Furthermore, rhGH/somatropin suppressed the phosphorylation of eukaryotic initiation factor-2α (eIF2α), upregulated the gene expression of activating transcription factor-4 (ATF4), GADD34, and glucose-regulated protein-78/binding immunoglobulin (GRP78/Bip). Moreover, it increased the glutathione level and reduced lipid peroxidation in the cerebral cortex. The VEGFR2 antagonist reversed the effect of rhGH/somatropin on PERK and IRE1α and boosted the apoptotic markers but neither affected p-eIF2α nor GADD34. Hence, we conclude that VEGFR2 activation by rhGH/somatropin plays a crucial role in assembling the BBB adherens junctions via its antioxidant capacity, ERS relief, and reducing endotoxemia in septic encephalopathy.

Preventive Administration of the Heat Shock Protein Hsp70 Relieves Endotoxemia-Induced Febrile Reaction in Pigeons ( ) and Rats

The stress-inducible 70 kDa heat shock protein (Hsp70) can exert a protective effect on endotoxemia and sepsis due to its ability to interact with immune cells and modulate the immune response. However, it remains unknown whether Hsp70 is able to relieve endotoxemia-induced fever. We carried out a comparative study of the effects of preventive administration of the human recombinant Hsp70 (HSPA1A) on lipopolysaccharide (LPS)-induced endotoxemia in pigeons and rats with preimplanted electrodes and thermistors for recording the thermoregulation parameters (brain temperature, peripheral vasomotor reaction, muscular contractile activity). Additionally, we analyzed the dynamics of the white blood cell (WBC) count in rats under the same conditions. It was found that preventive administration of Hsp70 relieves the LPS-induced febrile reaction in pigeons and rats and accelerates the restoration of the WBC count in rats. The data obtained suggest that these warm-blooded animals share a common physiological mechanism that underlies the protective effect of Hsp70.

Role of TRPM8 in switching between fever and hypothermia in adult mice during endotoxin-induced inflammation

Transient receptor potential melastatin 8 (TRPM8) functions in the sensing of noxious and innocuous colds; however, its significance in pathogen-induced thermoregulation remains unclear. In the present study, we investigated the role of TRPM8 in the regulation of endotoxin-induced body temperature control. The peripheral administration of low-dose lipopolysaccharide (LPS) at 50 ​μg/kg generated fever in wild-type (WT) mice, whereas it caused hypothermia in TRPM8 knockout (KO) animals. LPS-induced sickness responses such as decrease in body weight, and food and water intake were not different between WT and TRPM8 KO mice. TRPM8 KO mice exhibited more severe hypothermia and lower locomotor activity following the peripheral administration of high-dose LPS at 5 ​mg/kg compared with WT ones. An intracerebroventricular (i.c.v.) injection of either LPS at 3.6 ​μg/kg or interleukin-1β at 400 ​ng/kg elicited hypothermia in TRPM8 KO mice, in contrast to fever in WT animals. The peripheral administration of zymosan at 3 ​mg/kg also induced hypothermia in contrast to fever in WT mice. An i.c.v. injection of prostaglandin E₂ at 16 or 160 ​nmol/kg induced normal fever in both WT and TRPM8 KO mice. Infrared thermography showed significant decline of the interscapular skin temperature that estimates temperature of the brown adipose tissue, regardless of no alteration of its temperature in WT animals. Fos immunohistochemistry showed stronger Fos activation of hypothalamic thermoregulation-associated nuclei in TRPM8 KO mice compared with WT animals following the peripheral administration of low-dose LPS. Therefore, the present study indicates that TRPM8 is necessary for switching between fever and hypothermia during endotoxin-induced inflammation.

Low technology, mild controlled hypothermia for necrotizing enterocolitis treatment: an initiative to improve healthcare to preterm neonates

Necrotizing enterocolitis (NEC) treatment remains unchanged for years. Data suggest that mild controlled hypothermia could potentially improve NEC outcomes. Our units presented unfavourable outcomes on NEC. The aim was to assess our experience with low technology, mild controlled hypothermia on NEC outcomes, and improve preterm infants' healthcare. This was a single-center quality improvement study with retrospective cohort design at the neonatal intensive care unit in the university hospital. Forty-three preterm infants with NEC (Modified Bell's Stage II/III) were included: 19 in the control group (2015-2018) and 24 in the hypothermia group (2018-2020). The control group received standard treatment (fasting, abdominal decompression, and broad-spectrum antibiotics). The hypothermia group underwent cooling to 35.5 °C for 48 h after NEC diagnosis, along with conventional treatment. The primary outcomes are intestinal perforation, need for surgery, duration of parenteral nutrition, death, and extensive resection of the small intestine. There was no statistical difference in the NEC score. The hypothermia group required less surgery (aRR 0.40; 95% CI 0.19-0.85), presented less bowel perforation (aRR 0.39; 95% CI 0.18; 0.83), had a shorter duration of parenteral nutrition (aHR 5.28; 95% CI 1.88-14.89), did not need extensive intestinal resection, (0 vs 15.7%), and did not experience any deaths (0 vs 31.6%).Conclusions: In our experience, low technology, mild controlled hypothermia was feasible, not related to adverse effects, and effective treatment for NEC Modified Bell's Stage II/III. It avoided surgery, bowel perforation, and extensive intestinal resection; reduced mortality; and shortened parenteral nutrition duration. What is Known: • New approaches have been proposed to avoid enterocolitis incidence; however, the treatment of enterocolitis stage 2 has been the same for decades, and unfavourable outcomes remain despite conventional management. • Studies suggest that hypothermia can be an alternative to enterocolitis treatment. What is New: • Mild controlled hypothermia can be an additional practice to treat enterocolitis stage 2, is feasible, and is not related to adverse effects to preterm infants. • It can decrease surgery needs, duration of parenteral nutrition, and death and avoids extensive intestinal resection in preterm infants.

The Hypothermic Effect of Hydrogen Sulfide Is Mediated by the Transient Receptor Potential Ankyrin-1 Channel in Mice

Hydrogen sulfide (H₂S) has been shown in previous studies to cause hypothermia and hypometabolism in mice, and its thermoregulatory effects were subsequently investigated. However, the molecular target through which H₂S triggers its effects on deep body temperature has remained unknown. We investigated the thermoregulatory response to fast-(Na₂S) and slow-releasing (GYY4137) H₂S donors in C57BL/6 mice, and then tested whether their effects depend on the transient receptor potential ankyrin-1 (TRPA1) channel in Trpa1 knockout (Trpa1^−/−) and wild-type (Trpa1^+/+) mice. Intracerebroventricular administration of Na₂S (0.5–1 mg/kg) caused hypothermia in C57BL/6 mice, which was mediated by cutaneous vasodilation and decreased thermogenesis. In contrast, intraperitoneal administration of Na₂S (5 mg/kg) did not cause any thermoregulatory effect. Central administration of GYY4137 (3 mg/kg) also caused hypothermia and hypometabolism. The hypothermic response to both H₂S donors was significantly (p < 0.001) attenuated in Trpa1^−/− mice compared to their Trpa1^+/+ littermates. Trpa1 mRNA transcripts could be detected with RNAscope in hypothalamic and other brain neurons within the autonomic thermoeffector pathways. In conclusion, slow- and fast-releasing H₂S donors induce hypothermia through hypometabolism and cutaneous vasodilation in mice that is mediated by TRPA1 channels located in the brain, presumably in hypothalamic neurons within the autonomic thermoeffector pathways.

Targeting focal ischemic and hemorrhagic stroke neuroprotection: Current prospects for local hypothermia

Therapeutic hypothermia (TH) has applications dating back millennia. In modern history, however, TH saw its importation into medical practice where investigations have demonstrated that TH is efficacious in ischemic insults, notably cardiac arrest and hypoxic-ischemic encephalopathy. As well, studies have been undertaken to investigate whether TH can provide benefit in focal stroke (i.e., focal ischemia and intracerebral hemorrhage). However, clinical studies have encountered various challenges with induction and maintenance of post-stroke TH. Most clinical studies have attempted to use body-wide cooling protocols, commonly hindered by side effects that can worsen post-stroke outcomes. Some of the complications and difficulties with systemic TH can be circumvented by using local hypothermia (LH) methods. Additional advantages include the potential for lower target temperatures to be achieved and faster TH induction rates with LH. This systematic review summarizes the body of clinical and preclinical LH focal stroke studies and raises key points to consider for future LH research. We conclude with an overview of LH neuroprotective mechanisms and a comparison of LH mechanisms with those observed with systemic TH. Overall, whereas many LH studies have been conducted preclinically in the context of focal ischemia, insufficient work has been done in intracerebral hemorrhage. Furthermore, key translational studies have yet to be done in either stroke subtype (e.g., varied models and time-to-treat, studies considering aged animals or animals with co-morbidities). Few clinical LH investigations have been performed and the optimal LH parameters to achieve neuroprotection are unknown.

Ablation of PDE4B protects from Pseudomonas aeruginosa-induced acute lung injury in mice by ameliorating the cytostorm and associated hypothermia

Pseudomonas aeruginosa is a frequent cause of hospital-acquired lung infections characterized by hyperinflammation, antibiotic resistance, and high morbidity/mortality. Here, we show that the genetic ablation of one cAMP-phosphodiesterase 4 subtype, PDE4B, is sufficient to protect mice from acute lung injury induced by P aeruginosa infection as it reduces pulmonary and systemic levels of pro-inflammatory cytokines, as well as pulmonary vascular leakage and mortality. Surprisingly, despite dampening immune responses, bacterial clearance in the lungs of PDE4B-KO mice is significantly improved compared to WT controls. In wildtypes, P aeruginosa-infection produces high systemic levels of several cytokines, including TNF-α, IL-1β, and IL-6, that act as cryogens and render the animals hypothermic. This, in turn, diminishes their ability to clear the bacteria. Ablation of PDE4B curbs both the initial production of acute response cytokines, including TNF-α and IL-1β, as well as their downstream signaling, specifically the induction of the secondary-response cytokine IL-6. This synergistic action protects PDE4B-KO mice from the deleterious effects of the P aeruginosa-induced cytostorm, while concurrently improving bacterial clearance, rather than being immunosuppressive. These benefits of PDE4B ablation are in contrast to the effects resulting from treatment with PAN-PDE4 inhibitors, which have been shown to increase bacterial burden and dissemination. Thus, PDE4B represents a promising therapeutic target in settings of P aeruginosa lung infections.

Novel phenotypes of coronavirus disease: a temperature-based trajectory model

BACKGROUND

Coronavirus disease has heterogeneous clinical features; however, the reasons for the heterogeneity are poorly understood. This study aimed to identify clinical phenotypes according to patients' temperature trajectory.

METHOD

A retrospective review was conducted in five tertiary hospitals in Hubei Province from November 2019 to March 2020. We explored potential temperature-based trajectory phenotypes and assessed patients' clinical outcomes, inflammatory response, and response to immunotherapy according to phenotypes.

RESULTS

A total of 1580 patients were included. Four temperature-based trajectory phenotypes were identified: normothermic (Phenotype 1); fever, rapid defervescence (Phenotype 2); gradual fever onset (Phenotype 3); and fever, slow defervescence (Phenotype 4). Compared with Phenotypes 1 and 2, Phenotypes 3 and 4 had a significantly higher C-reactive protein level and neutrophil count and a significantly lower lymphocyte count. After adjusting for confounders, Phenotypes 3 and 4 had higher in-hospital mortality (adjusted odds ratio and 95% confidence interval 2.1, 1.1-4.0; and 3.3, 1.4-8.2, respectively), while Phenotype 2 had similar mortality, compared with Phenotype 1. Corticosteroid use was associated with significantly higher in-hospital mortality in Phenotypes 1 and 2, but not in Phenotypes 3 or 4 (p for interaction < 0.01). A similar trend was observed for gamma-globulin.

CONCLUSIONS

Patients with different temperature-trajectory phenotypes had different inflammatory responses, clinical outcomes, and responses to corticosteroid therapy.

Hyperactivation of the amygdala correlates with impaired social play behavior of prepubertal male rats in a maternal immune activation model

Maternal infection during pregnancy is an environmental risk factor for neurodevelopmental dysfunction, such as autism spectrum disorder (ASD). This study investigated the effect of maternal immune activation (MIA) on the behavior profile of prepubertal offspring and whether MIA alters the neuronal activation pattern of brain areas related to social play behavior. Pregnant Wistar rats received 500 μg/kg of lipopolysaccharide or saline solution on gestational day 16. Their offspring were tested using behavioral tasks to capture some of the core and associated ASD-like symptoms. Neuronal activation, indexed via c-fos expression after social play behavior, was evaluated in several brain areas. MIA had a number of adverse effects on dams and reduced the number of successful births and litter size. MIA induced sex-specific autistic-like features by a reduction in ultrasonic vocalizations in response to separation from the mother and nest, reduction in discrimination between neutral odors and their nest odor, moderate effect in stereotypies in the hole-board test, impaired risk assessment phenotype, and reduction in social play behavior without changes in locomotor activity only in prepubertal male offspring. A decrease in social play behavior may be associated with a decrease in the number of c-fos-positive cells in the prefrontal cortex and striatum, but hyperactivation of the basolateral and basomedial amygdala. Prenatal immune challenge results in ASD-like symptoms such as impaired risk assessment behavior, communication, and social interactions in male prepubertal offspring. Impaired social play behavior is correlated with neuronal hyperactivation in the amygdala.

Effect of temperature stress on gut-brain axis in mice: Regulation of intestinal microbiome and central NLRP3 inflammasomes

BACKGROUND

Temperature stress was reported to impact the gut-brain axis including intestinal microbiome and neuroinflammation, but the molecular markers involved remain unclear. We aimed to examine the effects of different temperature stress on the intestinal microbiome and central nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasomes.

MATERIALS AND METHODS

Mice models were established under low temperature (LT), room temperature (RT), high temperature (HT), and temperature variation (TV) respectively for seven days. We examined temperature-induced changes of intestinal microbiome composition and the levels of its metabolites short-chain fatty acids (SCFAs), as well as the expressions of central NLRP3 inflammasomes and inflammatory cytokines. Redundancy analysis and Spearman correlation analysis were performed to explore the relationships between microbiome and NLRP3 inflammasomes and other indicators.

RESULTS

HT and LT significantly increased the Alpha diversity of intestinal microbiome. Compared with RT group, Bacteroidetes were most abundant in LT group while Actinobacteria were most abundant in HT and TV groups. Nineteen discriminative bacteria were identified among four groups. LT increased the expressions of acetate and propionate while decreased that of NLRP3 inflammasomes; HT decreased the expression of butyrate while increased that of NLRP3 inflammasomes, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α; TV decreased the expression of propionate while increased that of NLRP3 inflammasomes and TNF-α. Microbiome distribution could significantly explain the differences in NLRP3 between comparison groups (LT&RT: R² = 0.82, HT&RT: R² = 0.86, TV&RT: R² = 0.94; P < 0.05). The discriminative bacteria were significantly correlated with SCFAs but were correlated with NLRP3 inflammasomes and cytokines in the opposite direction.

CONCLUSIONS

LT inhibits while HT and TV promote the activation of NLRP3 inflammasomes in brain, and intestinal microbiome and its metabolites may be the potential mediators. Findings may shed some light on the impact of temperature stress on gut-brain axis.

Non-contact infrared assessment of human body temperature: The journal Temperature toolbox

The assessment of human internal/core temperature (T core) is relevant in many scientific disciplines, but also for public health authorities when attempting to identify individuals with fever. Direct assessment of T core is often invasive, impractical on a large scale, and typically requires close contact between the observer and the target subject. Non-contact infrared thermometry (NCIT) represents a practical solution in which T core can potentially be assessed from a safe distance and in mass screening scenarios, by measuring skin temperature at specific anatomical locations. However, the COVID-19 pandemic has clearly demonstrated that these devices are not being used correctly, despite expert guided specifications available in International Standard Organization (ISO) documents. In this review, we provide an overview of the most pertinent factors that should be considered by users of NCIT. This includes the most pertinent methodological and physiological factors, as well as an overview on the ability of NCIT to track human T core. For practical use, we provide a checklist based on relevant ISO standards which are simple to follow and should be consulted prior to using NCIT for assessment of human T core. Our intention is for users of NCIT to adopt this checklist, which may improve the performance of NCIT for its ability to track T core.

Macrophage migration inhibitory factor as a diagnostic and predictive biomarker in sepsis: meta-analysis of clinical trials

The hunt for useful sepsis biomarkers is ongoing. Macrophage migration inhibitory factor (MIF) was implicated as a biomarker in sepsis, but its diagnostic and prognostic value has remained unclear in human studies. Here, we aimed at clarifying the value of MIF as a sepsis biomarker with the meta-analysis of clinical trials. PubMed, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched until December 2019. From the included studies, blood MIF levels and indicators of disease severity were extracted in septic and control patient groups. Twenty-one eligible studies were identified, including data from 1876 subjects (of which 1206 had sepsis). In the septic patients, blood MIF levels were significantly higher than in healthy controls with a standardized mean difference (SMD) of 1.47 (95% confidence interval, CI: 0.96-1.97; p < 0.001) and also higher than in patient groups with nonseptic systemic inflammation (SMD = 0.94; CI: 0.51-1.38; p < 0.001). Markedly greater elevation in blood MIF level was found in the more severe forms of sepsis and in nonsurvivors than in less severe forms and in survivors with SMDs of 0.84 (CI: 0.45-1.24) and 0.75 (CI: 0.40-1.11), respectively (p < 0.001 for both). In conclusion, blood MIF level is more elevated in systemic inflammation caused by infection (i.e., sepsis) compared to noninfectious causes. In more severe forms of sepsis, including fatal outcome, MIF levels are higher than in less severe forms. These results suggest that MIF can be a valuable diagnostic and prognostic biomarker in sepsis given that well-designed clinical trials validate our findings.

Peripheral neuroimmune interactions: selected review and some clinical implications

Purpose

To provide a brief and focused review on peripheral neuroimmune interactions and their implications for some clinical disorders.

Methods

Narrative review of the literature including of English-language articles published between 1985 and 2021 using PubMed and MEDLINE.

Results

Many studies on experimental models and in vitro indicate that there are close interactions between the neural and immune systems. Processes from sensory afferents and autonomic efferents co-localize with immune cells and interact at discrete anatomical sites forming neuroimmune units. These neuroimmune interactions are bidirectional and mediated by a wide range of soluble factors including neuropeptides, classical neurotransmitters, cytokines, and other molecules that mediate complex cross-talk among nerves and immune cells. Small-diameter sensory afferents express a wide range of receptors that respond directly to tissue damage or pathogen signals and to chemokines, cytokines, or other molecules released from immune cells. Reciprocally, immune cells respond to neurotransmitters released from nociceptive and autonomic fibers. Neuroimmune interactions operate both at peripheral tissues and at the level of the central nervous system. Both centrally and peripherally, glial cells have a major active role in this bidirectional communication.

Conclusions

Peripheral neuroimmune interactions are complex and importantly contribute to the pathophysiology of several disorders, including skin, respiratory, and intestinal inflammatory disorders typically associated with pain and altered barrier function. These interactions may be relevant for persistence of symptoms in disorders associated with intense immune activation.

CANPT Score: A Tool to Predict Severe COVID-19 on Admission

Background and Aims: Patients with critical coronavirus disease 2019 (COVID-19) have a mortality rate higher than 50%. The purpose of this study was to establish a model for the prediction of the risk of severe disease and/or death in patients with COVID-19 on admission.

Materials and Methods: Patients diagnosed with COVID-19 in four hospitals in China from January 22, 2020 to April 15, 2020 were retrospectively enrolled. The demographic, laboratory, and clinical data of the patients with COVID-19 were collected. The independent risk factors related to the severity of and death due to COVID-19 were identified with a multivariate logistic regression; a nomogram and prediction model were established. The area under the receiver operating characteristic curve (AUROC) and predictive accuracy were used to evaluate the model's effectiveness.

Results: In total, 582 patients with COVID-19, including 116 patients with severe disease, were enrolled. Their comorbidities, body temperature, neutrophil-to-lymphocyte ratio (NLR), platelet (PLT) count, and levels of total bilirubin (Tbil), creatinine (Cr), creatine kinase (CK), and albumin (Alb) were independent risk factors for severe disease. A nomogram was generated based on these eight variables with a predictive accuracy of 85.9% and an AUROC of 0.858 (95% CI, 0.823–0.893). Based on the nomogram, the CANPT score was established with cut-off values of 12 and 16. The percentages of patients with severe disease in the groups with CANPT scores <12, ≥12, and <16, and ≥16 were 4.15, 27.43, and 69.64%, respectively. Seventeen patients died. NLR, Cr, CK, and Alb were independent risk factors for mortality, and the CAN score was established to predict mortality. With a cut-off value of 15, the predictive accuracy was 97.4%, and the AUROC was 0.903 (95% CI 0.832, 0.974).

Conclusions: The CANPT and CAN scores can predict the risk of severe disease and mortality in COVID-19 patients on admission.

CANPT Score: A Tool to Predict Severe COVID-19 on Admission

Background and Aims: Patients with critical coronavirus disease 2019 (COVID-19) have a mortality rate higher than 50%. The purpose of this study was to establish a model for the prediction of the risk of severe disease and/or death in patients with COVID-19 on admission. Materials and Methods: Patients diagnosed with COVID-19 in four hospitals in China from January 22, 2020 to April 15, 2020 were retrospectively enrolled. The demographic, laboratory, and clinical data of the patients with COVID-19 were collected. The independent risk factors related to the severity of and death due to COVID-19 were identified with a multivariate logistic regression; a nomogram and prediction model were established. The area under the receiver operating characteristic curve (AUROC) and predictive accuracy were used to evaluate the model's effectiveness. Results: In total, 582 patients with COVID-19, including 116 patients with severe disease, were enrolled. Their comorbidities, body temperature, neutrophil-to-lymphocyte ratio (NLR), platelet (PLT) count, and levels of total bilirubin (Tbil), creatinine (Cr), creatine kinase (CK), and albumin (Alb) were independent risk factors for severe disease. A nomogram was generated based on these eight variables with a predictive accuracy of 85.9% and an AUROC of 0.858 (95% CI, 0.823-0.893). Based on the nomogram, the CANPT score was established with cut-off values of 12 and 16. The percentages of patients with severe disease in the groups with CANPT scores <12, ≥12, and <16, and ≥16 were 4.15, 27.43, and 69.64%, respectively. Seventeen patients died. NLR, Cr, CK, and Alb were independent risk factors for mortality, and the CAN score was established to predict mortality. With a cut-off value of 15, the predictive accuracy was 97.4%, and the AUROC was 0.903 (95% CI 0.832, 0.974). Conclusions: The CANPT and CAN scores can predict the risk of severe disease and mortality in COVID-19 patients on admission.

Lipoteichoic acid, a cell wall component of Gram-positive bacteria, induces sleep and fever and suppresses feeding

Fragments of the bacterial cell wall are bioactive microbial molecules that have profound effects on the function of the brain. Some of the cell wall constituents are common to both Gram-positive and Gram-negative bacteria, e.g., peptidoglycans, while other cell wall components are specific to either Gram-positive or Gram-negative microbes. Lipopolysaccharide (LPS), also called endotoxin, is found exclusively in Gram-negative bacteria, while lipoteichoic acid (LTA) is specific to Gram-positive bacteria. The effects of peptidoglycans, their fragments, and LPS are well characterized, they induce sleep, fever and anorexia. In the present study, we investigated the sleep, body temperature and food intake modulating effects of LTA. We found that intraperitoneal injection of 100 and 250 μg LTA from B. subtilis and S. aureus increases non-rapid-eye movement sleep (NREMS) in mice. The effects were dose-dependent, and the changes were accompanied by decreased motor activity and feeding as well as febrile responses. Intraperitoneal injection of 10 μg LTA induced monophasic increases in body temperature, while 100 and 250 μg LTA from B. subtilis induced initial hypothermia followed by fever. Treatment with 250 μg LTA from S. aureus elicited monophasic hypothermia. Administration of 300 μg/kg LTA from S. aureus directly into the portal vein elicited similar sleep responses in rats but did not affect body temperature. The sleep-modulating effects of LTA were similar to that of LPS in mice, although LTA appears to be less potent. These findings suggest that the role of LTA in signaling by Gram-positive bacteria in the host body is analogous to the role of LPS/endotoxin in signaling by Gram-negative microbes. LTA may play a role in the development of sickness response in clinically manifest Gram-positive bacterial infections and may contribute to sleep signaling by the commensal intestinal microbiota.