Perspective on fever: The basic science and conventional medicine

Antipyretic effect of inhaled Tetrastigma hemsleyanum polysaccharide on substance and energy metabolism in yeast-induced pyrexia mice via TLR4/NF-κb signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Tetrastigma hemsleyanum Diels et Gilg, is one of the perennial evergreen plants with grass vine, which has obvious curative effect on severe infectious diseases. Although Tetrastigma hemleyanum has long been recognized for its capacity of antipyretic and antitoxic, its specific mechanism is unknown.

AIM OF THE STUDY

To evaluate the antipyretic effect of Tetrastigma hemleyanum polysaccharide (THP) on mice with dry yeast-induced fever, and to explore its specific antipyretic mechanism.

METHODS

In this study, THP was administered by aerosol in febrile mice. The rectal temperatures of treated animals were monitored at different time points. Histopathological evaluation and various inflammatory indexes were used to assess inflammatory damage. The concentration variations of the central neurotransmitter, endocrine system, substance and energy metabolism indicators were measured to explore the physiological mechanism. Quantitative real-time PCR, Western bolt and Immunohistochemistry were performed to identify the correlation between antipyretic and TLR4/NF-κB signaling pathway.

RESULTS

THP reduced the body temperature of febrile mice induced by dry yeast, as well as the levels of thermogenic cytokines and downregulated the contents of thermoregulatory mediators. THP alleviated the pathological damage of liver and hypothalamus caused by fever. In addition, THP decreased the secretion of thyroid hormone, substance and energy metabolism related indicators. Furthermore, THP significantly suppressed TLR4/NF-κB signaling pathway-related indicators.

CONCLUSIONS

In conclusion, our results suggest that inhaled THP exerts antipyretic effect by mediating the thermoregulatory mediator, decreasing the content of pyrogenic factors to lower the body temperature, and eventually restoring the high metabolic level in the body to normal via inhibiting TLR4/NF-κB signaling pathway. The study provides a reasonable pharmacodynamic basis for the treatment of polysaccharide in febrile-related diseases.

Exploring potential impacts of pregnancy-related maternal immune activation and extracellular vesicles on immune alterations observed in autism spectrum disorder

Autism Spectrum Disorder (ASD) is a set of neurodevelopmental disorders usually observed in early life, with impacts on behavioral and social skills. Incidence of ASD has been dramatically increasing worldwide, possibly due to increase in awareness/diagnosis as well as to genetic and environmental triggers. Currently, it is estimated that ∼1% of the world population presents ASD symptoms. In addition to its genetic background, environmental and immune-related factors also influence the ASD etiology. In this context, maternal immune activation (MIA) has recently been suggested as a component potentially involved in ASD development. In addition, extracellular vesicles (EVs) are abundant at the maternal-fetal interface and are actively involved in the immunoregulation required for a healthy pregnancy. Considering that alterations in concentration and content of EVs have also been associated with ASD, this article raises a debate about the potential roles of EVs in the processes surrounding MIA. This represents the major differential of the present review compared to other ASD studies. To support the suggested correlations and hypotheses, findings regarding the roles of EVs during pregnancy and potential influences on ASD are discussed, along with a review and update concerning the participation of infections, cytokine unbalances, overweight and obesity, maternal anti-fetal brain antibodies, maternal fever, gestational diabetes, preeclampsia, labor type and microbiota unbalances in MIA and ASD.

Impact of an Educational Program on Improving Nurses’ Management of Fever: An Experimental Study

Background: Despite a public information campaign “To Break the Myth of Fever”, nurses continued to overtreat fever. This study hypothesized that the campaign lacked the detailed rationale essential to alter nurses’ attitudes and behaviors. Aim: To evaluate the effect of the educational program on nurses’ knowledge, attitudes, and behaviors related to fever management. Design: A randomized experimental design using a time series analysis. Methods: A random sample of 58 medical/surgical nurses was evenly divided into an intervention and a control group. The intervention group received an educational program on fever and fever management. Both groups completed a pretest and four posttests using investigator-developed instruments: a questionnaire on knowledge and attitudes about fever management and a fever treatment checklist to audit charts. Results: The intervention group had markedly higher knowledge scores and reduced use of ice pillows at all four posttests, as well as lower use of antipyretics overall, except for the first posttest, despite no sustained change in attitude. Conclusions: An educational program for fever management can effectively improve clinical nurses’ knowledge and attitudes about fever management.

Influence of EPs 7630 on Antipyretic Comedication and Recovery from Acute Tonsillopharyngitis in Children: A Meta-analysis of Randomized, Placebo-Controlled, Clinical Trials

Objective Acute tonsillopharyngitis (ATP) is a common, seasonal infection of predominantly viral origin. Management is aimed at shortening the course of the disease and restoring the comfort of the patient. We performed a meta-analysis to investigate whether treatment with the Pelargonium sidoides extract EPs 7630 reduces the use of antipyretic comedication (i.e., acetaminophen) in children suffering from ATP.

Methods Studies were identified from clinical trial registries and medical literature. Randomized, placebo-controlled, clinical trials investigating EPs 7630 in children with ATP and reporting the coadministration of paracetamol were eligible. Based on the raw data of eligible trials, we analyzed cumulative paracetamol use, as well as the ability to attend school at the end of treatment. Three trials including a total of 345 children aged 6 to 10 years and suffering from non-β-hemolytic streptococcal ATP were identified and eligible. Children were administered EPs 7630 or placebo for 6 days.

Results Compared with placebo, EPs 7630 reduced the cumulative paracetamol dose by an average of 449 mg (95% confidence interval [CI]: 252–646 mg; p < 0.001). A total of 19.1% (EPs 7630) and 71.5% (placebo) of children were still unable to attend school at the end of the treatment (risk ratio = 0.28; 95% CI: 0.16–0.48; p < 0.001).

Conclusion Our meta-analysis demonstrates that EPs 7630 reduced the use of antipyretic comedication and accelerated recovery.

Fever Induced by Zymosan A and Polyinosinic-Polycytidylic Acid in Female Rats: Influence of Sex Hormones and the Participation of Endothelin-1

Sex differences in the immune response can also affect the febrile response, particularly the fever induced by lipopolysaccharide (LPS). However, other pathogen-associated molecular patterns, such as zymosan A (Zym) and polyinosinic-polycytidylic acid (Poly I:C), also induce fever in male rats with a different time course of cytokine release and different mediators such as endothelin-1 (ET-1). This study investigated whether female sex hormones affect Zym- and Poly I:C-induced fever and the involvement of ET-1 in this response. The fever that was induced by Zym and Poly I:C was higher in ovariectomized (OVX) female rats compared with sham-operated female rats. Estrogen replacement in OVX females reduced Zym- and Poly I:C-induced fever. The ET_B receptor antagonist BQ788 reversed the LPS-induced fever in cycling females but not in OVX females. BQ788 did not alter the fever that was induced by Zym or Poly I:C in either cycling or OVX females. These findings suggest that the febrile response in cycling females is lower, independently of the stimulus that is inducing it and is probably controlled by estrogen. Also, ET-1 seems to participate in the febrile response that was induced by LPS in males and cycling females but not in the LPS-induced fever in OVX females. Additionally, ET-1 was not involved in the febrile response that was induced by Zym or Poly I:C in females.

Effects of Fever on 18F-FDG Distribution In Vivo: a Preliminary Study

PURPOSE

Elevated body temperature might change glucose metabolism in human organs. The purpose of this study is to explore ¹⁸F-FDG distribution in febrile patients on the day of ¹⁸F-FDG PET/CT scanning and compare it with patients with a normal temperature.

PROCEDURES

¹⁸F-FDG PET/CT was performed on 69 febrile patients and 82 patients with a normal temperature. Patient sociodemographic data, blood glucose levels before PET/CT, body temperature on the day of the exam, and laboratory test results were collected. Maximal standard uptake values (SUV_max) in the brain, mediastinal blood pool, liver, spleen, and the bone marrow were compared.

RESULTS

Compared with the controls, SUV_max of the febrile patients was significantly lower in the brain, mediastinal blood pool, and the liver (p < 0.01), and higher in the spleen and bone marrow (p < 0.01). In the febrile group, SUV_max was not significantly different between the FDG burden and non-FDG burden patients (p > 0.05). Body temperature was found negatively correlated with SUV_max in the brain (r = - 0.646), mediastinal blood pool (r = - 0.530), and the liver (r = - 0.384), and positively correlated with the SUV_max in the spleen (r = 0.592) and bone marrow (r = 0.651). Multivariate linear regression established body temperature on the day of PET/CT as an independent affecting factor (p < 0.01) for the SUV_max in the brain, mediastinal blood pool, liver, spleen, and bone marrow. The SUV in the brain, liver, and mediastinal blood pool remained different (p < 0.05) after corrected with the SUV_max in the blood pool or liver.

CONCLUSIONS

Fever influences ¹⁸F-FDG distribution in multiple human tissues and organs. Altered ¹⁸F-FDG distribution in vivo might affect results of disease lesion detection and tumor therapy response assessment. Correction with blood pool or liver SUV fails to cancel the effects of fever. The day of fever should be avoided for PET/CT scan, especially in assessing tumor therapy response.

New Insights into the Role of Glutathione in the Mechanism of Fever

Glutathione is one of the most important and potent antioxidants. The development of pharmacological compounds that can either increase or decrease glutathione concentrations has allowed investigation into the role of glutathione in various biological processes, including immune responses. Recent findings have shown that glutathione not only affects certain factors involved in immunological processes but also modifies complex immune reactions such as fever. Until recently, it was not known why some patients do not develop fever during infection. Data suggest that fever induction is associated with oxidative stress; therefore, antioxidants such as glutathione can reduce pyrexia. Surprisingly, new studies have shown that low glutathione levels can also inhibit fever. In this review, we focus on recent advances in this area, with an emphasis on the role of glutathione in immune responses accompanied by fever. We describe evidence showing that disturbed glutathione homeostasis may be responsible for the lack of fever during infections. We also discuss the biological significance of the antipyretic effects produced by pharmacological glutathione modulators.

Antipyretic drugs in patients with fever and infection: literature review

BACKGROUND

antipyretic drugs are routinely administered to febrile patients with infection in secondary care. However, the use of antipyretics to suppress fever during infection remains a controversial topic within the literature. It is argued that fever suppression may interfere with the body's natural defence mechanisms, and may worsen patient outcomes.

METHOD

a literature review was undertaken to determine whether the administration of antipyretic drugs to adult patients with infection and fever, in secondary care, improves or worsens patient outcomes.

RESULTS

contrasting results were reported; two studies demonstrated improved patient outcomes following antipyretic administration, while several studies demonstrated increased mortality risk associated with antipyretics and/or demonstrated fever's benefits during infection. Results also demonstrated that health professionals continue to view fever as deleterious.

CONCLUSION

the evidence does not currently support routine antipyretic administration. Considering patients' comorbidities and symptoms of their underlying illness will promote safe, evidence-based and appropriate administration of antipyretics.

Faster recovery and reduced paracetamol use - a meta-analysis of EPs 7630 in children with acute respiratory tract infections

OBJECTIVE

Fever is a very common adaptive immune response in acute respiratory tract disorders during infancy. Antipyretic / analgesic drugs such as paracetamol (acetaminophen) are widely used to improve the comfort of the child but may cause medically unneeded antipyresis and rare but potentially serious side effects. We assess whether treatment with Pelargonium sidoides extract EPs 7630 reduces the administration of paracetamol in children with acute tonsillopharyngitis (ATP) or acute bronchitis (AB).

DESIGN

Meta-analysis of randomised, placebo-controlled clinical trials.

METHODS

We searched clinical trial registries (ISRCTN, ClinicalTrials.gov ) and medical literature (MEDLINE, EMBASE), for randomised, placebo-controlled trials investigating the administration of EPs 7630 to children with ATP or AB and reporting the co-administration of paracetamol. Based on the individual participant data of the eligible trials, study populations were characterized according to sex and age, and meta-analyses were performed for cumulative paracetamol use and ability to attend school at treatment end.

RESULTS

Six trials including a total of 523 children aged 6-10 years (EPs 7630: 265; placebo: 258) and suffering from non-β-hemolytic streptococcal ATP (3 trials) or from AB (3 trials) were identified and eligible. Children received EPs 7630 or placebo for 6 (ATP) or 7 days (AB). Compared to placebo, EPs 7630 reduced the cumulative dose of paracetamol in 5 out of the 6 trials, by an average of 244 mg (Hedges' g; - 0.28; 95% confidence interval: [- 0.53; - 0.02]; p < 0.03). At treatment end, 30.2% (EPs 7630) and 74.4% (placebo) of the children were still unable to attend school (risk ratio: 0.43; 95% confidence interval: [0.29; 0.65]; p < 0.001).

CONCLUSIONS

In children aged 6-10 years with AB or ATP, EPs 7630 alleviated the symptom burden and accelerated recovery. Although EPs 7630 has no known antipyretic effect, concomitant use of paracetamol was reduced.

Patient reported symptoms, body temperature and hospital mortality: an observational study in a low resource healthcare environment

BACKGROUND

Fever is a common presenting complaint of patients, especially in sub-Saharan Africa. Although most medical authorities consider fever to be synonymous with an elevated body temperature the relationship of the complaint of fever made by patients to temperature has not been well defined.

AIM

This study examined the relationship of the complaint of fever to temperature on and after admission and in-hospital mortality.

METHOD

Observational study in a low-resource Ugandan mission hospital.

RESULTS

Out of 2122 alert patients admitted between 9 August 2016 and 5 January 2018, 349 (16.4%) complained of fever: these patients were no more likely to have an abnormal temperature or die in-hospital than those not complaining of fever. Of the 707 alert patients admitted after 1 July 2017, 422 were interviewed in detail about their symptoms: only rigors, feeling intermittently hot and cold, and anorexia were statistically related to the complaint of fever, and only rigors to an admission temperature >38°C. No symptom or sign was associated with a temperature ≤36°C: cold and clammy skin was the only finding associated with in-hospital death. On logistic regression the only independent predictors of mortality were: the National Early Warning Score, impaired mobility on presentation and cold and clammy skin.

CONCLUSION

In this study, the term fever used by patients and raised body temperature were not synonymous. Although fever and related symptoms reported by patients are common presenting complaints only the finding of cold and clammy skin was associated with in-hospital mortality.

Febrile temperature reprograms by redox-mediated signaling the mitochondrial metabolic phenotype in monocyte-derived dendritic cells

Fever-like hyperthermia is known to stimulate innate and adaptive immune responses. Hyperthermia-induced immune stimulation is also accompanied with, and likely conditioned by, changes in the cell metabolism and, in particular, mitochondrial metabolism is now recognized to play a pivotal role in this context, both as energy supplier and as signaling platform. In this study we asked if challenging human monocyte-derived dendritic cells with a relatively short-time thermal shock in the fever-range, typically observed in humans, caused alterations in the mitochondrial oxidative metabolism. We found that following hyperthermic stress (3h exposure at 39°C) TNF-α-releasing dendritic cells undergo rewiring of the oxidative metabolism hallmarked by decrease of the mitochondrial respiratory activity and of the oxidative phosphorylation and increase of lactate production. Moreover, enhanced production of reactive oxygen and nitrogen species and accumulation of mitochondrial Ca²⁺ was consistently observed in hyperthermia-conditioned dendritic cells and exhibited a reciprocal interplay. The hyperthermia-induced impairment of the mitochondrial respiratory activity was (i) irreversible following re-conditioning of cells to normothermia, (ii) mimicked by exposing normothermic cells to the conditioned medium of the hyperthermia-challenged cells, (iii) largely prevented by antioxidant and inhibitors of the nitric oxide synthase and of the mitochondrial calcium porter, which also inhibited release of TNF-α. These observations combined with gene expression analysis support a model based on a thermally induced autocrine signaling, which rewires and sets a metabolism checkpoint linked to immune activation of dendritic cells.

Lower temperatures reduce type I interferon activity and promote alphaviral arthritis

Chikungunya virus (CHIKV) belongs to a group of mosquito-borne alphaviruses associated with acute and chronic arthropathy, with peripheral and limb joints most commonly affected. Using a mouse model of CHIKV infection and arthritic disease, we show that CHIKV replication and the ensuing foot arthropathy were dramatically reduced when mice were housed at 30°C, rather than the conventional 22°C. The effect was not associated with a detectable fever, but was dependent on type I interferon responses. Bioinformatics analyses of RNA-Seq data after injection of poly(I:C)/jetPEI suggested the unfolded protein response and certain type I interferon responses are promoted when feet are slightly warmer. The ambient temperature thus appears able profoundly to effect anti-viral activity in the periphery, with clear consequences for alphaviral replication and the ensuing arthropathy. These observations may provide an explanation for why alphaviral arthropathies are largely restricted to joints of the limbs and the extremities.

La fiebre en el niño: una mirada reflexiva a las prácticas de cuidado

Objetivo: Realizar un análisis crítico-reflexivo de las prácticas rutinarias de los profesionales de enfermería y de los cuidadores familiares en el cuidado del niño con fiebre, a fin de incentivar un cuidado basado en evidencia científica que asegure el bienestar infantil.Síntesis de contenido: Se realizó una revisión bibliográfica de artículos científicos publicados entre los años 2007 y 2017, en las bases de datos ebscohost, ScienceDirect, medline, PubMed, cinahl, Web of Science y cuiden®, para lo cual se utilizaron los descriptores y sus combinaciones en español, portugués e inglés Fiebre; Cuidadores; Niño. Se elaboró un compendio de 45 artículos seleccionados y analizados que contenía las prácticas de cuidado con convergencias, divergencias y complementariedades.Los resultados se agruparon en los siguientes cinco temas: Concepción histórica de la fiebre; La fiebrefobia:una concepción en las actuales prácticas de cuidado; El baño de esponja:una práctica ancestral controvertida; El uso de antipiréticos: una rutina en contravía de la salud y la vidade los niños; La fiebre: en busca de una mirada desde su beneficio.Conclusiones: La concepción de la fiebre infantil centrada en el miedo y en el daño permanece. Las acciones de cuidado más comunes, como el baño de esponja y el uso/abuso de antipiréticos, son cuestionadas desde la evidencia científica, demostrando los efectos deletéreos que producen en la salud del niño. El cuidado del niño, después de una evaluación individualizada, deberá enfocarse en el confort, en un ambiente fresco y tranquilo y en el aumento de la ingesta de líquidos para evitar la deshidratación u otras complicaciones.

Incidence and differential characteristics of culture-negative fever following pancreas transplantation with anti-thymocyte globulin induction

BACKGROUND

Limited data are available on the incidence and characteristics of culture-negative fever following pancreas transplantation (PTx) with anti-thymocyte globulin (ATG) induction. Our study aims to better define the features of culture-negative fever, so it can be delineated from infectious fever, hopefully helping clinicians to guide antibiotic therapy in this high-risk patient population.

METHODS

We performed a retrospective cohort study of postoperative fever among 198 consecutive patients undergoing PTx at our center between August 1, 2004 and December 31, 2014. Fever was classified as culture-negative if there was neither a positive culture nor a documented clinical diagnosis of infection.

RESULTS

Fever was identified in 113 patients; 66 were deemed to be infectious, 39 were culture-negative, and 8 were indeterminate. High body mass index of recipient (odds ratio 1.87, 95% confidence interval: 1.15-3.03, P = 0.011) was a significant factor associated with culture-negative fever in multivariate analysis. No patients with culture-negative fever were diagnosed with infiltrates or effusion on chest radiography. In addition, an increase in white blood cell count, C-reactive protein, and serum amylase was less prominent in culture-negative fever. Culture-negative fever developed most frequently at postoperative 7 or 14 days, showing a biphasic curve.

CONCLUSION

Culture-negative fever develops in a substantial proportion of patients early after PTx. The awareness of the possibility and clinical features of post-transplant culture-negative fever might help clinicians to guide antibiotic therapy in this high-risk patient population, especially following ATG induction and early steroid withdrawal.

INSURMOUNTABLE HEAT: THE EVOLUTION AND PERSISTENCE OF DEFENSIVE HYPERTHERMIA

Fever, the rise in body temperature set point in response to infection or injury, is a highly conserved trait among vertebrates, and documented in many arthropods. Fever is known to reduce illness duration and mortality. These observations present an evolutionary puzzle: why has fever continued to be an effective response to fast-evolving pathogenic microbes across diverse phyla, and probably over countless millions of years? Framing fever as part of a more general thermal manipulation strategy that we term defensive hyperthermia, we hypothesize that the solution lies in the independent contributions to pathogen fitness played by virulence and infectivity. A host organism deploying defensive hyperthermia alters the ecological environment of an invading pathogen. To the extent that the pathogen evolves to be able to function effectively at elevated temperatures, it disadvantages itself at infecting the next (thermonormative) host, becoming more likely to be thwarted by that host's immune system and outcompeted by wild ecotype conspecifics (a genetically distinct strain adapted to specific environmental conditions) that, although more vulnerable to elevated temperatures, operate more effectively at the host's normal temperature. We evaluate this hypothesis in light of existing evidence concerning pathogen thermal specialization, and discuss theoretical and translational implications of this model.

Thermostability of IFN-γ and IP-10 release assays for latent infection with Mycobacterium tuberculosis: A TBnet study

INTRODUCTION

Interferon-γ (IFN-γ) inducible protein 10kD (IP-10) and IFN-γ release assays (IGRAs) are immunodiagnostic tests aiming to identify the presence of specific cellular immune responses, interpreted as markers for latent infection with Mycobacterium tuberculosis. Incubation at higher temperatures could affect IFN-γ and IP-10 responsiveness in order to improve the performance of IP-10 release assays and IGRAs.

AIM

The aim of this study was to assess the robustness of whole blood based IP-10 release assay and IGRAs and the effect of hyper-thermic incubation (39 °C) on the diagnostic accuracy of IP-10 release assay and IGRAs.

RESULTS

We included 65 patients with confirmed pulmonary tuberculosis and 160 healthy controls from 6 European centres collaborating in the TBnet. In patients, IP-10 responses increased 1.07 (IQR 0.90-1.36) fold and IFN-γ responses decreased 0.88 (IQR 0.57-1.02) fold, with 39 °C compared to 37 °C incubation temperature. At 37 °C IGRA sensitivity was 85% and IP-10 sensitivity was 82%, whereas specificity was 97% for both tests (p > 0.8). These minor changes observed as a result of hyper-thermic incubation were not sufficient to impact IGRA and IP-10 release assay test performance.

CONCLUSION

The performance of IGRA and IP-10 release assays is robust despite variations in the incubation temperature between 37 °C and 39 °C.

Correlation Between Body Temperature and Survival Rate in Patients With Hospital-Acquired Bacteremia

Background:

Fever is a complex and major sign of a patient’s acute response to infection. However, analysis of the risks and benefits associated with the change in body temperature of an infected host remains controversial.

Objective:

To examine the relationship between the intensity of the change in body temperature and the mortality of patients with hospital-acquired bacteremia.

Design:

A prospective observational study.

Method:

Subjects were hospitalized adult patients who developed clinical signs of infection 48 hr or more after admission and had documented bacterial growth in blood culture. The maximum body temperature (maxTe) during the early period of infection measurements (i.e., the day before, the day of, and 2 days after the day of blood culture) was used to indicate the intensity of the body temperature response. Patients were categorized as discharged alive or died in hospital. Cox regression analysis was employed to analyze the data.

Results:

The cohort consisted of 502 subjects. The mean maxTe of subjects was 38.6°C, and 14.9% had a maxTe lower than 38.0°C. The in-hospital mortality rate was 18.9%. The highest in-hospital mortality was found in subjects with a maxTe lower than 38°C (30.7%). Multivariate Cox regression analysis determined that the maxTe and the severity of comorbidity are the two variables associated with in-hospital mortality.

Conclusions:

Lack of a robust febrile response may be associated with greater risk of mortality in patients with bacteremia. Clinicians must be vigilant in identifying patients at risk for a blunted febrile response to bacteremia for more intensive monitoring.

Therapeutic hypothermia after cardiac arrest and return of spontaneous circulation: it's complicated

Providing evidence-based care to patients with return of spontaneous circulation after a cardiac arrest is a recent complex innovation. Once resuscitated patients must be assessed for appropriateness for therapeutic hypothermia, be cooled in a timely manner, maintained while hypothermic, rewarmed within a specified time frame, and then assessed for whether hypothermia was successful for the patient through neuroprognostication. Nurses caring for therapeutic hypothermia patients must be knowledgeable and prepared to provide care to the patient and family. This article provides an overview of the complexity of therapeutic hypothermia for patients with return of spontaneous circulation in the form of a case study.