Fine-tuning immune surveillance by fever-range thermal stress

Association between Acute and Chronic Inflammatory States: A Case-Control Study

BACKGROUND

Fever is the hallmark of efficient acute inflammatory response, which may be disrupted in chronic inflammatory conditions. The "continuum theory" proposes that the return of acute inflammatory states with high fever predicts improvement in chronic diseases during treatment. Our objective was to investigate the observation made, during classical homeopathic treatment, that such an association exists between chronic inflammation and efficient acute inflammation.

METHODS

In a case-control study, the reports of patients diagnosed with chronic inflammatory conditions with at least 6 months of follow-up under homeopathic treatment were retrospectively sampled from homeopathic medical practices from Greece, India, Romania and Russia. Twenty patients who improved under homeopathic treatment and 20 age-matched controls of those who did not improve were selected. The occurrence of common acute infectious diseases with fever during the follow-up period was investigated.

RESULTS

The average age of the cases and controls was 28.4 (SD: 16.64) and 27.9 (SD: 17.19) years respectively. 18/20 cases and 4/20 controls developed common infectious diseases with fever. Cramer's V co-efficient value was found to be 0.551 (p < 0.01), indicating that improvement was more in patients with fever than without. Odds ratio of improving with respect to development of acute infectious diseases was 36.0 (95% CI: 5.8 to 223.5). The binary logistic regression model indicated significant contribution of occurrence of acute infections with fever as a predictor for improvement in chronic inflammatory disease.

CONCLUSIONS

Classical homeopathic clinical observations indicate an association between chronic inflammatory status in the body and the ability to mount efficient acute inflammation. In this case-control study, the occurrence of common infections with fever during treatment heralded improvement in chronic inflammatory disease. Further powered studies are necessary to substantiate this finding.

Long-term health effects of antipyretic drug use in the aging population: a systematic review

It is unclear whether fever suppression in the elderly provides long-term benefits or poses risks due to their distinct immune profiles and body temperature regulation compared to younger individuals. This study aimed to assess the long-term health effects of antipyretic treatment during infections in the elderly. A systematic review was conducted, including studies that compared antipyretic treatment with other drugs, therapies, placebo, or no treatment. PubMed, Embase and Cochrane CENTRAL databases were searched. Primary and secondary outcomes were the onset or worsening of chronic inflammatory diseases, fever reduction, length of hospital stay, patient satisfaction, mortality, laboratory indicators of morbidity, and progression to complications, respectively. Out of 11,481 studies screened, 17 were included (two randomized controlled trials [RCTs], seven observational studies, one case series, and seven case reports). None investigated the primary outcome or patient-reported outcomes. The risk of bias in the included studies ranged from unclear to high. Due to the heterogeneity of the studies, a narrative synthesis was conducted, as meta-analysis was not feasible. Antipyretics showed a significant reduction of fever in RCTs. Five studies reported a significant drop in blood pressure, and one showed significant mortality from antipyretics. Morbidity indicators and length of stay were available only in the studies that reported adverse events. The certainty of evidence, assessed using GRADE, was low to very low for all outcomes. Evidence regarding the long-term benefit or harm from fever suppression with antipyretics during infections in the elderly is insufficient.

Fever temperatures impair hemolysis caused by strains of Escherichia coli and Staphylococcus aureus

Hemolysis modulates susceptibility to bacterial infections and predicts poor sepsis outcome. Hemolytic bacteria use hemolysins to induce erythrocyte lysis and obtain the heme that is essential for bacterial growth. Hemolysins are however potent immunogens and infections with hemolytic bacteria may cause a reversible fever response from the host that will aid in pathogen clearance. We hypothesized that fever temperatures impact the growth and infectivity of two hemolytic bacteria that are known to evoke fever in patients. To that end, we used high-sensitivity microcalorimetry to measure the evolution of heat production in fever-inducing strains of Escherichia coli and Staphylococcus aureus, under different temperature conditions. We determined specific bacterial aggregation profiles at temperatures equal to or exceeding 38.5 °C. Two melting temperatures peaks ranged from 38 °C to 43 °C for either species, a feature that we assigned to the formation of hemolysin aggregates of different oligomerization order. In order to measure the role of fever temperatures on hemolysis, we incubated the pathogens on blood agar plates at relevant temperatures, measuring the presence of hemolysis at 37 °C and its absence at 40.5 °C, respectively. We conclude that fever temperatures affect the kinetics of hemolysin pore formation and subsequently the hemolysis of red blood cells in vitro. We reveal the potential of microcalorimetry to monitor heat response from fever inducing bacterial species. Furthermore, these results help establish an additional positive role of febrile temperatures in modulating the immune response to infections, through the abolishment of hemolysis.

Long-term health effects of antipyretic drug use in the ageing population: protocol for a systematic review

Background: Fever is suppressed with drugs due to discomfort and risk of organ damage. However, there is some compelling evidence for the benefits of fever. The elderly are a special population in this regard as they have a blunted fever response. The benefit-harm balance of antipyretic use in this population is unclear.  

This study aims to provide the synthesized best evidence regarding long-term health effects of antipyretic treatment in the elderly during infections, investigating the onset/worsening of common chronic diseases, for e.g., thyroid disorders, connective tissue diseases and chronic obstructive pulmonary disease/asthma.

Methods: A systematic review will be performed to establish the best evidence available regarding antipyretic treatment in the elderly, searching databases such as Medline, Embase and Cochrane CENTRAL from their inception till date for all types of studies. Studies that consider the drugs in analgesic role will be excluded. The search will be reported following the ‘Preferred Reporting Items for Systematic Reviews and Meta-Analyses’ (PRISMA) guidelines. Randomized control trials, quasi experimental studies, observational studies, case series and reports will be included. The primary outcome measure being onset/worsening of chronic inflammatory diseases. Other outcomes include relief of symptoms, length of hospital stay, patient satisfaction, mortality, blood/immune parameters indicative of morbidity and complications of the infection.

Risk of biases in randomized studies will be assessed through the Cochrane risk of bias tool. For other study types, appropriate tools such as CASP/QUIPS/Cochrane non-randomised studies tool will be used. Meta-analysis will be conducted on the Cochrane RevMan software and where pooling of data is not possible, a narrative synthesis will be performed. Overall certainty of evidence will be assessed through the GRADE approach.

Discussion: The study aims to provide evidence regarding benefit-harm balance of antipyretic use in the elderly population to inform clinical practice and future research. 

Systematic review registration: PROSPERO CRD42020160854

The Genetic Architecture of Early Body Temperature and Its Correlation With Salmonella Pullorum Resistance in Three Chicken Breeds

New-born chicks are vulnerable to bacterial infections and not good at regulating body temperature. There is a close relationship between thermal regulation and immunity, however, the underlying mechanism is not well understood. Salmonella Pullorum (SP) is a major concern in developing countries and causes significant economic losses in poultry industry. Early body temperature (EBT) has previously shown to be correlated with host immunity and resistance to pullorum disease. In this study, we challenged three independent chick populations (Beijing You, Dwarf and Rhode Island Red) with SP at 4 days of age, and rectal temperature was measured before and after the SP attack from 2 to 7 days of age. Host defense to SP was evaluated by survival and spleen SP carrier status. The results showed that chicks with higher EBT before SP infection tend to have higher resistance to later SP attack in two populations (Dwarf and Beijing You). The association between EBT before SP attack and SP resistance was non-significant in Rohde Island Red population (P = 0.06), but the trend was consistent with the other two populations. We also found low to moderate heritability in all three populations for EBT before and after the SP attack ranging from 0.14 to 0.20. Genome-wide association studies identified several genomic regions and biological pathways determining EBT before SP attack, which provides candidate functional genes of this trait. Our results reveal the genetic determination of EBT, and the relationship between EBT and SP resistance, providing an alternative strategy for improving SP resistant activities in chicken.

Febrile temperatures increase in vitro antibody affinity for malarial and dengue antigens

Fever is a regulated increase of the body temperature resulting from both infectious and non-infectious causes. Fever is known to play a role in modulating immune responses to infection, but the potential of febrile temperatures in regulating antigen binding affinity to antibodies has not been explored. Here we investigated this process under in vitro conditions using Isothermal titration calorimetry and ELISA. We used selected malarial and dengue antigens against specific monoclonal antibodies, and observed a marked increase in the affinity of these antibody-antigen complexes at 40°C, compared to physiological (37°C) or pathophysiological temperatures (42°C). Induced thermal equilibration of the protein partners at these temperatures in vitro, prior to measurements, further increased their binding affinity. These results suggest another positive and adaptive role for fever in vivo, and highlight the favourable role of thermal priming in enhancing protein-protein affinity for samples with limited availability.

Immunology, Immunotherapy, and Translating Basic Science into the Clinic for Bladder Cancer

The Fourth Annual Albert Institute Bladder Cancer Care and Research Symposium was held from September 14th–16th in Houston, Texas. The symposium covered a range of topics relevant to bladder cancer, including basic science aspects of immunology and immunotherapy that inform clinical management; intravesical therapy for non-muscle invasive disease; understanding the nuances of carcinoma in situ; and optimizing patient care and outcomes following therapy. The moving landscape of bladder cancer from an industry perspective was also discussed.

In the following sections we discuss intrinsic and extrinsic factors, including the immune microenvironment and sex bias, in the context of bladder cancer; how these influence tumor development, progression, and treatment strategies; and how the interpretation of immune features in relation to molecular subtypes informs both treatment decisions and response. We conclude with a summary of key points that will need to be addressed to ensure best use of new knowledge in this area for improved clinical management of patients with bladder cancer.

The Impact of Hyperthermia on Receptor-Mediated Interleukin-6 Regulation in Mouse Skeletal Muscle

In inflammatory cells, hyperthermia inhibits lipopolysaccharide (LPS)-induced interleukin-6 (IL-6) gene expression and protein secretion. Since hyperthermia alone stimulates IL-6 in skeletal muscle, we hypothesized that it would amplify responses to other receptor-mediated stimuli. IL-6 regulation was tested in C2C12 myotubes and in soleus during treatment with epinephrine (EPI) or LPS. In EPI-treated myotubes (100 ng/ml), 1 h exposure at 40.5°C-42°C transiently increased IL-6 mRNA compared to EPI treatment alone at 37°C. In LPS-treated myotubes (1 μg/ml), exposure to 41°C-42°C also increased IL-6 mRNA. In isolated mouse soleus, similar amplifications of IL-6 gene expression were observed in 41°C, during both low (1 ng/ml) and high dose (100 ng/ml) EPI, but only in high dose LPS (1 μg/ml). In myotubes, heat increased IL-6 secretion during EPI exposure but had no effect or inhibited secretion with LPS. In soleus there were no effects of heat on IL-6 secretion during either EPI or LPS treatment. Mechanisms for the effects of heat on IL-6 mRNA were explored using a luciferase-reporter in C2C12 myotubes. Overexpression of heat shock factor-1 (HSF-1) had no impact on IL-6 promoter activity during EPI stimulation, but elevated IL-6 promoter activity during LPS stimulation. In contrast, when the activator protein-1 (AP-1) element was mutated, responses to both LPS and EPI were suppressed in heat. Using siRNA against activating transcription factor-3 (ATF-3), a heat-stress-induced inhibitor of IL-6, no ATF-3-dependent effects were observed. The results demonstrate that, unlike inflammatory cells, hyperthermia in muscle fibers amplifies IL-6 gene expression to EPI and LPS. The effect appears to reflect differential engagement of HSF-1 and AP-1 sensitive elements on the IL-6 gene, with no evidence for involvement of ATF-3. The functional significance of increased IL-6 mRNA expression during heat may serve to overcome the well-known suppression of protein synthetic pathways occurring during heat shock.

Fever, immunity, and molecular adaptations

The heat shock response (HSR) is an ancient and highly conserved process that is essential for coping with environmental stresses, including extremes of temperature. Fever is a more recently evolved response, during which organisms temporarily subject themselves to thermal stress in the face of infections. We review the phylogenetically conserved mechanisms that regulate fever and discuss the effects that febrile-range temperatures have on multiple biological processes involved in host defense and cell death and survival, including the HSR and its implications for patients with severe sepsis, trauma, and other acute systemic inflammatory states. Heat shock factor-1, a heat-induced transcriptional enhancer is not only the central regulator of the HSR but also regulates expression of pivotal cytokines and early response genes. Febrile-range temperatures exert additional immunomodulatory effects by activating mitogen-activated protein kinase cascades and accelerating apoptosis in some cell types. This results in accelerated pathogen clearance, but increased collateral tissue injury, thus the net effect of exposure to febrile range temperature depends in part on the site and nature of the pathologic process and the specific treatment provided.

Measuring soluble ICAM-1 in African populations

The level of plasma soluble ICAM-1 (sICAM-1) has been associated with the pathogenesis of several diseases. Previously, a commercial antibody was reported not to recognize an ICAM-1 allele known as ICAM-1kilifi prevalent among African populations. However, that study was based on 19 samples from African Americans of whom 13 had the wild type allele, five heterozygotes and one homozygote. Here, we compare plasma sICAM-1 measures using three different commercial antibodies in samples from Kenyan children genotyped for ICAM-1kilifi allele. We show that two of these antibodies have some degree of deficiency in detecting the ICAM-1kilifi allele. Consideration of the antibody used to measure sICAM-1 is important as up to 30% of the populations in Africa harbour this allele.

Fever in Cancer Treatment: Coley's Therapy and Epidemiologic Observations

In the fall of 1890, an athletic, self-possessed, and thoughtful 17-year-old girl, who had just returned from an adventurous trip to Alaska where she had hurt her hand in a trivial accident, went to see a young, innovative surgeon in his new practice in New York City. Barely out of Harvard Medical School, he was a rising star in New York surgical circles, and the young woman asked him for help with her poorly healing, swollen, and naggingly painful injury. This visit had a far-reaching effect on cancer research, American philanthropy, and the career of the young man, William Coley, MD (1862-1936, Figure 1). The patient, Elisabeth Dashiell, confidant and close friend of John D. Rockefeller, Jr, was diagnosed by Coley with a highly aggressive round cell sarcoma, and despite radical surgery and in spite of Coley's undoubtedly fine surgical skills and intensive care, a rapid progression of the cancer, immense suffering, and Elisabeth's death a few months later could not be prevented.

High endothelial venules as traffic control points maintaining lymphocyte population homeostasis in lymph nodes

Millions of lymphocytes enter and exit mammal lymph nodes (LNs) each day, accessing the parenchyma via high endothelial venules (HEVs) and egressing via lymphatics. Despite this high rate of cellular flux and the many entry and exit sites within a given LN, the number of lymphocytes present in a resting LN is extraordinary stable over time, raising the question of how this steady-state is maintained. Here we have examined the anatomic details of lymphocyte movement in HEVs, finding that HEVs create pockets within which lymphocytes reside for several minutes before entering the LN proper. The function of these pockets was revealed in experiments performed under conditions in which lymphocyte egress from the LN was compromised by any of several approaches. Under such conditions, the HEVs pockets behaved as "waiting areas" in which lymphocytes were held until space was made available to them for entry into the parenchyma. Thus, rather than being simple entry ports, HEVs act as gatekeepers able to stack, hold and grant lymphocytes access to LN parenchyma in proportion to the rate of lymphocyte egress from the LN, enabling the LN to maintain a constant steady-state cellularity while supporting the extensive cellular trafficking necessary for repertoire scanning.