Diurnal Variation of Circulating Interleukin-6 in Humans: A Meta-Analysis

Heart Failure, Kidney Function, and Elderly Age, Rather than Levofloxacin Therapy, Are Associated with QTc Prolongation in COVID-19 Patients

Background: Prolongation of the QT interval is directly related to the risk of ventricular arrhythmias and sudden cardiac death. Age, comorbidities, and treatment schemes have been shown to influence its prolongation and may also significantly affect the course of SARS-CoV-2 infection. Fluoroquinolones, widely used during the COVID-19 pandemic, are known for their ability to prolong the QT interval. Risk of ventricular arrhythmias has also been reported in patients with infectious diseases, and this risk may have been associated with high levels of interleukin-6 (IL-6). Purpose: The aim of this study is to evaluate the effect of levofloxacin on the corrected QT interval in patients with COVID-19, as well as to identify sociodemographic, clinical, and biochemical parameters associated with QTc interval prolongation among patients with COVID-19. Patients and Methods: The medical records of 93 patients hospitalized for COVID-19 were retrospectively analyzed, focusing on the presence of comorbidities and treatment with levofloxacin. Selected sociodemographic, clinical, and biochemical parameters were then statistically analyzed, with emphasis on their effect on the corrected QTc interval. The QTc interval was calculated according to the Bazett formula. Results: Levofloxacin use was not significantly associated with QTc interval. Statistical analysis identified creatinine, heart failure and atrial fibrillation as significant predictors of QTc interval prolongation. The trends towards QTc interval prolongation observed with hypokalaemia and hypertension suggest that these factors may also contribute to QTc interval variability and should be taken into account when assessing arrhythmia risk. Conclusions: Our retrospective study indicates that QTc prolongation results from the interplay of multiple factors.

Utilizing blood inflammatory markers in alcohol studies: Considerations and recommendations for study design, sample collection, and data analysis

A large body of evidence suggests that heavy alcohol use is associated with dysregulated immune function, and that immune dysfunction in turn contributes to the pathophysiology of alcohol use disorder (AUD). As such, alcohol researchers have increasingly begun to include measurements of immune function-primarily peripheral circulating cytokines-in human studies, with the goal of testing associations with clinically-relevant behavioral measures. To date, findings and implications from these studies have been inconsistent and difficult to interpret, likely due to methodological challenges related to study design and implementation. In particular, the existing literature has demonstrated sample processing concerns, differences in assay methods, limited selection of analytes, and sample selection biases, all of which may contribute to inconsistent results. We briefly review the field, discuss these and other challenges, and propose guidance for designing studies on inflammation among heavy-drinking human participants. We note that conducting such studies requires appreciable consideration and planning, and ideally should involve an interdisciplinary team of experts, including immunologists, physiologists, and technical experts in bioassays, alongside experts in the field of interest (e.g., AUD). We highlight the importance of considering participant selection, analyte selection, sample collection, sample handling and storage, and assay methods, and suggest that the field move towards standardization of procedures and reporting. We propose that undertaking these changes in study design and implementation should produce consilience in findings and aid in our overall understanding of the complex relationship between alcohol exposure and immune function.

Peripheral immune cell response to stimulation stratifies Parkinson's disease progression from prodromal to clinical stages

The motor stage of Parkinson's disease (PD) can be preceded for years by a prodromal stage characterized by non-motor symptoms like REM sleep behavior disorder (RBD), hyposmia, and constipation. Here, we show that multiple stages of idiopathic PD, including the pre-motor prodromal stage, can be stratified according to the inflammatory responses to stimulation of peripheral blood mononuclear cells ex vivo. IFNγ stimulation of isolated monocytes reveals increased stimulation-dependent secretion of TNF, IL-1β, and IL-8 in prodromal PD relative to moderate stage PD. Additionally, T cells stimulated with CD3/CD28 co-stimulatory beads show diminished proinflammatory cytokine secretion in early-moderate PD relative to prodromal. Receiver operating characteristic curves demonstrate that several cytokines produced by stimulated monocytes show high predictive utility for distinguishing prodromal PD individuals from neurologically healthy controls. Moreover, immune stimulation reveals deficits in CD8+ T-cell mitochondrial health in moderate PD, with relative mitochondrial health in CD8+ T cells being positively correlated with stimulation-dependent secretion of IL-1β, IL-8, and IL-10 in T cells from prodromal PD subjects. Dysregulated mitochondrial health in immune cells may contribute to peripheral inflammation and PD progression, and ex vivo stimulation-based assays have the potential to reveal novel biomarkers for patient stratification and progression with immune endophenotypes.

Circadian Oscillation of Leukocyte Subpopulations and Inflammatory Cytokines over a 24-H Period in Horses

The objective of the present study was to investigate the influence of daily rhythms on the immune and inflammatory systems in horses, considering white blood cell count (WBCs), leukocyte subpopulations (neutrophils, basophils, eosinophils, lymphocytes, and monocytes), CD4+, and CD8+ lymphocyte populations, interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Ten Italian Saddle horses (7-12 years old, body weight 480 ± 30 kg) underwent blood sampling every 4 h over a 24-h period. The COSINOR method was used to identify rhythms and their parameters. A one-way analysis of variance (ANOVA) was applied to identify the differences in acrophase and robustness, and a multiple correlation analysis model (Pearson) was used to evaluate the relationships among the investigated parameters. WBCs, leukocyte subpopulations, CD4+, CD8+, IL-1β, IL-6, and TNFα exhibited daily rhythmicity. In particular, white WBCs, lymphocytes, IL-1β, and IL-6 reached their acrophases during the dark phase, while neuthrophils, CD4+, CD8+, and TNFα showed a diurnal acrophase. One-way ANOVA showed a statistical difference in the acrophase among the investigated parameters (p < 0.0001). The Pearson correlation matrix showed positive and negative relationships among the parameters. Circadian rhythms should be taken into consideration with the daily fluctuations in immune and inflammatory biomarkers to develop good management practices and improve welfare in horses.

A Cross Sectional Study of Cytokines in Women with Refractory Detrusor Overactivity versus Controls

INTRODUCTION AND HYPOTHESIS

Previous work has suggested that refractory detrusor overactivity (DO) was commonly associated with urinary tract infection (UTI), which can lead to inflammatory changes in the bladder. This study aimed to investigate the concentrations of urinary cytokines in a large sample of women with refractory detrusor overactivity (DO) and age matched controls.

METHODS

The urinary concentration of 27 cytokines in 140 women (95 with refractory DO and 45 age matched controls (women without urge incontinence)) was determined using the Human Cytokine 27-plex Assay. Cytokine concentrations were correlated with a "UTI score", the presence or absence of bacteriuria or pyuria on the day of sample collection and a previous history of UTI.

RESULTS

Pro-inflammatory cytokines were increased in refractory DO women compared to the controls. In women with refractory DO, the UTI score significantly correlated with urinary cytokine concentrations in 15 of the 22 cytokines detected. A previous history of UTI did not affect urinary cytokine concentrations in refractory DO women with no current UTI. Increasing pyuria was associated with increasing concentrations of urinary cytokines.

CONCLUSION

Careful comparison of cytokine concentrations in women with refractory DO versus age matched controls has shown that changes in pro-inflammatory cytokines are related to the UTI disease burden, suggesting that an underlying inflammatory response, together with UTI, may be an aetiological contributor to the development of refractory DO.

Sample Preparation for Metabolomic Analysis in Exercise Physiology

Metabolomics investigates final and intermediate metabolic products in cells. Assessment of the human metabolome relies principally on the analysis of blood, urine, saliva, sweat, and feces. Tissue biopsy is employed less frequently. Understanding the metabolite composition of biosamples from athletes can significantly improve our knowledge of molecular processes associated with the efficiency of training and recovery. Such knowledge may also lead to new management opportunities. Successful execution of metabolomic studies requires simultaneous qualitative and quantitative analyses of numerous small biomolecules in samples under test. Unlike genomics and proteomics, which do not allow for direct assessment of enzymatic activity, metabolomics focuses on biochemical phenotypes, providing unique information about health and physiological features. Crucial factors in ensuring the efficacy of metabolomic analysis are the meticulous selection and pre-treatment of samples.

Peripheral immune cell response to stimulation stratifies Parkinson's disease progression from prodromal to clinical stages

The motor stage of idiopathic Parkinson's disease (iPD) can be preceded for years by a prodromal stage characterized by non-motor symptoms like REM sleep behavior disorder (RBD). Here, we show that multiple stages of iPD, including the pre-motor prodromal stage, can be stratified according to the inflammatory and immunometabolic responses to stimulation of peripheral blood mononuclear cells ex vivo. We identified increased stimulation-dependent secretion of TNF, IL-1β, and IL-8 in monocytes from RBD patients and showed diminished proinflammatory cytokine secretion in monocytes and T cells in early and moderate stages of PD. Mechanistically, immune activation revealed deficits in CD8+ T-cell mitochondrial health in moderate PD, and relative mitochondrial health in CD8+ T cells was positively correlated with stimulation-dependent T-cell cytokine secretion across the PD spectrum. Dysregulated immunometabolism may drive peripheral inflammation and PD progression, and ex vivo stimulation-based assays have potential to reveal novel biomarkers for patient stratification and progression with immune endophenotypes.

Alterations in Circadian Rhythms, Sleep, and Physical Activity in COVID-19: Mechanisms, Interventions, and Lessons for the Future

Although the world is acquitting from the throes of COVID-19 and returning to the regularity of life, its effects on physical and mental health are prominently evident in the post-pandemic era. The pandemic subjected us to inadequate sleep and physical activities, stress, irregular eating patterns, and work hours beyond the regular rest-activity cycle. Thus, perturbing the synchrony of the regular circadian clock functions led to chronic psychiatric and neurological disorders and poor immunological response in several COVID-19 survivors. Understanding the links between the host immune system and viral replication machinery from a clock-infection biology perspective promises novel avenues of intervention. Behavioral improvements in our daily lifestyle can reduce the severity and expedite the convalescent stage of COVID-19 by maintaining consistent eating, sleep, and physical activity schedules. Including dietary supplements and nutraceuticals with prophylactic value aids in combating COVID-19, as their deficiency can lead to a higher risk of infection, vulnerability, and severity of COVID-19. Thus, besides developing therapeutic measures, perpetual healthy practices could also contribute to combating the upcoming pandemics. This review highlights the impact of the COVID-19 pandemic on biological rhythms, sleep-wake cycles, physical activities, and eating patterns and how those disruptions possibly contribute to the response, severity, and outcome of SARS-CoV-2 infection.

IL-6 and Cardiovascular Risk: A Narrative Review

PURPOSE OF REVIEW

The objective of this narrative review is to summarize data from recently published prospective observational studies that analyze the association between circulating interleukin-6 (IL-6) levels and cardiovascular clinical or imaging endpoints.

RECENT FINDINGS

Higher levels of IL-6 are associated with a higher risk of cardiovascular death, major adverse cardiovascular events, myocardial infarction, stroke, peripheral artery disease, and heart failure. Imaging studies have also shown an association between IL-6 and carotid intima-media thickness progression, carotid plaque progression, severity, and vulnerability. These observations have been consistent across a wide range of study populations and after adjusting for traditional and emerging risk factors including high-sensitivity C-reactive protein. Robust epidemiologic evidence supports IL-6 as a central mediator of cardiovascular risk along with human genetic studies and mechanistic experiments. Ongoing clinical studies are testing the therapeutic hypothesis of IL-6 inhibition in patients with atherosclerotic cardiovascular disease or heart failure.

Time-dependent characteristics of analytical measurands

OBJECTIVES

Biological variation is a relevant component of diagnostic uncertainty. In addition to within-subject and between-subject variation, preanalytical variation also includes components that contribute to biological variability. Among these, daily recurring, i.e., diurnal physiological variation is of particular importance, as it contains both a random and a non-random component if the exact time of blood collection is not known.

METHODS

We introduce four time-dependent characteristics (TDC) of diurnal variations for measurands to assess the relevance and extent of time dependence on the evaluation of laboratory results.

RESULTS

TDC address (i) a threshold for considering diurnality, (ii) the expected relative changes per time unit, (iii) the permissible time interval between two blood collections at different daytimes within which the expected time dependence does not exceed a defined analytical uncertainty, and (iv) a rhythm-expanded reference change value. TDC and their importance will be exemplified by the measurands aspartate aminotransferase, creatine kinase, glucose, thyroid stimulating hormone, and total bilirubin. TDCs are calculated for four time slots that reflect known blood collection schedules, i.e., 07:00-09:00, 08:00-12:00, 06:00-18:00, and 00:00-24:00. The amplitude and the temporal location of the acrophase are major determinates impacting the diagnostic uncertainty and thus the medical interpretation, especially within the typical blood collection time from 07:00 to 09:00.

CONCLUSIONS

We propose to check measurands for the existence of diurnal variations and, if applicable, to specify their time-dependent characteristics as outlined in our concept.

Whole-Body Cryotherapy Reduces Systemic Inflammation in Healthy Adults: Pilot Cohort Study

BACKGROUND

Chronically elevated inflammation is implicated in many conditions, including obesity, metabolic syndrome, and cardiovascular disease, and has been associated with increased mortality risk. Whole-body cryotherapy (W-BC) is a promising modality to treat inflammation with demonstrated benefits for clinical subpopulations including those with arthritis, obesity, and type 2 diabetes. However, it is unclear whether the benefit from W-BC extends to healthy individuals prior to chronic disease-related inflammation. In addition, the long-term durability of W-BC effect is unknown.

OBJECTIVE

This study investigates the inflammatory response to W-BC in healthy adults with a biomarker of inflammation, high-sensitivity C-reactive protein (hsCRP), and clinical biomarkers of metabolism including fasting glucose, hemoglobin A1c (HbA1c), low-density lipoprotein (LDL) and high-density lipoprotein (HDL), and triglycerides.

METHODS

Fifteen individuals (n=9 female) participated in frequent recreational W-BC (3 minutes of cold exposure at -110 ℃) over approximately 9 months and had blood draws at baseline plus follow-up visits. Biomarkers were modeled as linear functions of W-BC sessions received in the month prior to blood draw.

RESULTS

The mean amount of W-BC received was 6.78 (SD 4.26) times per month with the cumulative total ranging from 13 to 157 W-BC sessions over the course of the study. On average, participants completed 1-2 sessions per week throughout the intervention. The number of W-BC sessions were associated with decreased hsCRP (-0.14 mg/L in hsCRP per W-BC session; P<.01) and with durability of up to 9 months. Increased W-BC was also associated with a downward trend in fasting glucose. This trend failed to reach significance at 1 month (-0.73 mg/dL in fasting glucose per W-BC session; P<.10) but was significant for 2- and 3-month windows (P<.05). HbA1c was increased significantly after 9 months (P<.01); however, the change occurred within normal ranges (difference=0.13% and <5.7%) and was not clinically significant. There was no association between W-BC and LDL cholesterol, HDL cholesterol, or triglycerides (P>.10), although LDL trended lower over the time period examined (P=.07).

CONCLUSIONS

These results suggest that W-BC beneficially impacts systemic inflammation by lowering hsCRP levels in healthy individuals and may also have some modulating effect on fasting glucose.

Intracellular metabolome elucidates the time-of-day-dependent response to hydrogen peroxide in salmonid gill epithelial cells

The internal timekeeping system regulates the daily cycle of physiological and behavioural changes in living organisms. This rhythmic phenomenon also influences cellular responses to reactive oxygen species, such as hydrogen peroxide (H2O2). However, the temporal interaction between H2O2 and fish mucosal cells is not well understood. This study examined the temporal variations of immunological and physiological responses to H2O2 in salmonid gill cells using the RTgill-W1 cell line. The results showed that gene expression levels varied during a 24-h cycle but did not exhibit rhythmicity. The presence of a 12-h light-dark cycle (12L:12D) signal increased gene expression levels compared to a 24-h dark cycle (0L:24D). To investigate whether the time of day affects the defences in gills, cells were exposed to H2O2 at two different times (Zeitgebertime 2, ZT2, or ZT14). Although significant expression changes were observed in genes related to stress and NF-κB signalling, only a limited time-dependent pattern of response to H2O2 was observed. The intracellular metabolome of gill cells was primarily composed of organic acid and derivatives, organoheterocyclic compounds, benzoids, organic oxygen and nitrogen compounds. Exposure to H2O2 at ZT2 led to significant changes in the metabolome compared to the control group, while no such changes were observed at ZT14. Within the control groups, the concentrations of 11 metabolites significantly varied between ZT2 and ZT14, with higher levels at ZT14. These metabolites were involved in arginine biosynthesis, amino acid metabolism, and nitrogen metabolism. In contrast, the level of 26 metabolites significantly varied between ZT2 and ZT14 in H2O2-exposed groups, with lower levels at ZT14. Comparing control and H2O2-exposed groups at ZT2, 38 metabolites were affected, primarily organic acid and derivatives and organic oxygen compounds. Functional annotation revealed that these altered metabolites were involved in 15 different pathways, with valine, leucine, and isoleucine biosynthesis being the most affected. This study reveals the presence of a time-dependent response to H2O2 in salmonid gill cells, which is reflected in the intracellular metabolome. The findings provide new insights into the temporal regulation of mucosal defences in fish.

Immunological correlates of suicidality among adolescents with internalizing symptoms

Background

Suicide is a leading cause of death in adolescents and young adults globally. Well-established risk factors for suicide are depression and past suicide attempts. People experiencing suicidality may represent a distinct neurobiological group of people with depression. Because converging evidence has implicated inflammation in depression, we sought to investigate relationships between suicidality and immune markers in youth experiencing diverse mood and anxiety symptoms. We hypothesized that adolescents with suicidality would exhibit a unique immune signature.

Methods

Adolescents underwent semi-structured interviews and completed self-reported measures to assess psychopathology, including suicidality (suicidal ideation, plans, or attempts). Fasting blood samples were collected, cultured with and without lipopolysaccharide (LPS) to stimulate an inflammatory response, and analyzed for 41 immune analytes. To assess how immune function related to suicidality categorically and dimensionally, we conducted group comparisons and correlations while controlling for multiple comparisons using false discovery rate (FDR). To further uncover subtle immune-suicidality relationships, we employed a data-driven approach using factor analysis to extract major immune factors, each of which was subsequently correlated with suicidality measures.

Results

Among 126 participants, 29 were healthy controls and 97 participants had internalizing symptoms; within the clinical group, 57 experienced suicidality. Three immune analytes differed between healthy controls, suicidal, and non-suicidal adolescents with internalizing symptoms in the LPS condition: Flt-3L (p FDR = 0.0246), GM-CSF (p FDR = 0.0246), and IFN-γ (p FDR = 0.0246). These analytes were negatively correlated with the Beck Scale for Suicide Ideation (BSSI): Flt-3L (ρ = -0.19, p = 0.04); GM-CSF (ρ = -0.26, p = 0.004); IFN-γ (ρ =-0.33, p = 0.0003). GM-CSF also negatively correlated with number of suicide attempts (ρ = -0.39, p = 0.003). Factor analysis reduced 41 analytes to several common immune factors across experimental conditions, with Flt-3L, GM-CSF, and IFN-γ all loading heavily onto immune factors that were hypoactive in suicidality. Through this data-driven approach, we detected further associations between suicidality and immune factors across all conditions.

Conclusions

Peripheral immune function may be distinctly altered in adolescent suicidality. Future work should examine immune-suicidality relationships longitudinally.

Serum cytokines and inflammatory proteins in individuals with heroin use disorder: potential mechanistically based biomarkers for diagnosis

Opioid use disorders cause major morbidity and mortality, and there is a pressing need for novel mechanistic targets and biomarkers for diagnosis and prognosis. Exposure to mu-opioid receptor (MOR) agonists causes changes in cytokine and inflammatory protein networks in peripheral blood, and also in brain glia and neurons. Individuals with heroin use disorder (iHUD) show dysregulated levels of several cytokines in the blood. However, there is limited data on a comprehensive panel of such markers in iHUD versus healthy controls (HC), especially considered as a multi-target biomarker. We used a validated proximity extension assay for the relative quantification of 92 cytokines and inflammatory proteins in the serum of iHUD on medication-assisted therapy (MAT; n = 21), compared to HC (n = 24). Twenty-nine targets showed significant group differences (primarily iHUD>HC), surviving multiple comparison corrections (p = 0.05). These targets included 19 members of canonical cytokine families, including specific chemokines, interleukins, growth factors, and tumor necrosis factor (TNF)-related proteins. For dimensionality reduction, data from these 19 cytokines were entered into a principal component (PC) analysis, with PC1 scores showing significant group differences (iHUD > HC; p < 0.0001). A receiver-operating characteristic (ROC) curve analysis yielded an AUROC = 91.7% (p < 0.0001). This PC1 score remained a positive predictor of being in the HUD group in a multivariable logistic regression, that included select demographic/clinical variables. Overall, this study shows a panel of cytokines that differ significantly between iHUD and HC, providing a multi-target "cytokine biomarker score" for potential diagnostic purposes, and future examination of disease severity.

Sleep-wake behavior and responses to sleep deprivation and immune challenge of protein kinase RNA-activated knockout mice

Protein Kinase RNA-activated (PKR) is an enzyme that plays a role in many systemic processes, including modulation of inflammation, and is implicated in neurodegenerative diseases, such as Alzheimer's disease (AD). PKR phosphorylation results in the production of several cytokines involved in the regulation / modulation of sleep, including interleukin-1β, tumor necrosis factor-α and interferon-γ. We hypothesized targeting PKR would alter spontaneous sleep of mice, attenuate responses to sleep deprivation, and inhibit responses to immune challenge. To test these hypotheses, we determined the sleep-wake phenotype of mice lacking PKR (knockout; PKR-/-) during undisturbed baseline conditions; in responses to six hours of sleep deprivation; and after immune challenge with lipopolysaccharide (LPS). Adult male mice (C57BL/6J, n = 7; PKR-/-, n = 7) were surgically instrumented with EEG recording electrodes and an intraperitoneal microchip to record core body temperature. During undisturbed baseline conditions, PKR -/- mice spent more time in non-rapid eye movement sleep (NREMS) and rapid-eye movement sleep (REMS), and less time awake at the beginning of the dark period of the light:dark cycle. Delta power during NREMS, a measure of sleep depth, was less in PKR-/- mice during the dark period, and core body temperatures were lower during the light period. Both mouse strains responded to sleep deprivation with increased NREMS and REMS, although these changes did not differ substantively between strains. The initial increase in delta power during NREMS after sleep deprivation was greater in PKR-/- mice, suggesting a faster buildup of sleep pressure with prolonged waking. Immune challenge with LPS increased NREMS and inhibited REMS to the same extent in both mouse strains, whereas the initial LPS-induced suppression of delta power during NREMS was greater in PKR-/- mice. Because sleep regulatory and immune responsive systems in brain are redundant and overlapping, other mediators and signaling pathways in addition to PKR are involved in the responses to acute sleep deprivation and LPS immune challenge.

Myokine secretion during moderate-intensity physical activity: Dose-response of interleukin 6 to walking duration

During vigorous physical activity, contracting muscles secrete a variety of immunomodulatory and metabolic factors called myokines that perform a variety of functions. Foremost among these is interleukin 6 (IL-6), which increases fatty acid mobilization and stimulates anti-inflammatory cytokine release. Despite being well characterized in vigorous exercise contexts, whether IL-6 is secreted during moderate-intensity activities such as walking is unclear. This is especially pertinent as regular walking is one of the oldest and most common forms of physical activity and comes with a variety of health benefits, which may be coordinated in part by IL-6 signaling. To test the hypothesis that IL-6 release occurs during evolutionarily normal physical activity contexts like long distance walking, we performed a dose-response experiment to test the effect of walking duration on IL-6 secretion. Thirteen participants completed four moderate-intensity walking trials (55% HRmax) of varying durations (30 min, 1 h, 2 h, and 3 h) in a randomized order with intervening washout periods of at least 1 week. Using a linear mixed effects model, we found that IL-6 levels modestly increased during only the 2 h and 3 h walking trials. These results suggest that small frequent increases in IL-6 signaling may be an important mechanism underlying the health benefits of regular walking. Furthermore, this finding raises the possibility that IL-6 secretion is an adaptation to fuel physical activity, especially during periods of negative energy balance.

Association between psychiatric admissions in patients with schizophrenia and IL-6 plasma levels polygenic score

Schizophrenia diagnosis and admission history were associated with a polygenic score (PGS) for schizophrenia based on a subset of variants that act by modifying the expression of genes whose expression is also modified by antipsychotics. This gene set was enriched in cytokine production. Interleukin-6 (IL-6) is the only cytokine whose plasma levels were associated both with schizophrenia diagnosis and with acute decompensations in the largest meta-analysis. Therefore, we hypothesized that an IL-6 PGS, but not other cytokines PGSs, would be associated with schizophrenia chronicity/psychiatric admissions. Using the IL-6 PGS model from The PGS Catalog, IL-6 PGS was calculated in 427 patients with schizophrenia and data regarding admission history. Association between IL-6 PGS and chronicity, measured as number and duration of psychiatric admissions, or ever readmission was analyzed by multivariate ordinal and logistic regression, respectively. Specificity of results was assessed by analysis of PGSs from the other cytokines at The PGS Catalog with meta-analytic evidence of association with schizophrenia diagnosis or acute decompensations, IL-1RA, IL-4, IL-8, and IL-12. IL-6 PGS was associated with schizophrenia chronicity, explaining 1.51% of variability (OR = 1.29, 95% CI 1.07-1.55, P = 0.007). There was no association with ever readmission. Other cytokines PGSs were not associated with chronicity. Association with IL-6 PGS was independent of association with schizophrenia PGS. Our results provide evidence that genetically regulated higher levels of IL-6 are involved in schizophrenia chronicity, highlighting the relevance of immunity processes for a subgroup of patients.

Associations between sickness behavior, but not inflammatory cytokines, and psychiatric comorbidity in chronic pain

OBJECTIVES

Approximately one in five adults experiences chronic pain, often in co-occurrence with depression, insomnia, anxiety, and lower self-rated health. Elevated levels of cytokines, e.g. tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 8 (IL-8), and interleukin 10 (IL-10), have been identified in patients with chronic pain. Depression, insufficient sleep, poor self-rated health, and pain intensity have also been associated with inflammatory biomarkers. This study aimed to investigate the interrelationships between inflammatory biomarkers and depression, insomnia, anxiety, self-rated health, sickness behavior, and pain intensity in patients with chronic pain.

METHODS

Self-report questionnaires and blood samples analyzed for plasma levels of inflammatory biomarkers were collected from 80 adult patients with chronic pain. Associations between inflammatory biomarkers (TNF-α, IL-6, IL-8, IL-10, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR)) and depression, insomnia, anxiety, self-rated health, sickness behavior, and pain intensity, were analyzed using bivariate Spearman rank correlation coefficients and regression analyses.

RESULTS

Participants were mainly women (72.5 %), with a mean age of 50.8 years, and a reported mean pain duration of 16.7 years. There were significant correlations between insomnia and CRP (rs =.26, p <.05); sex and ESR (rs =.29, p <.05); age and IL-6 (rs =.29, p <.05) and IL-8 (rs =.30, p <.05); BMI and IL-6 (rs =.50, p <.001), CRP (rs =.63, p <.001) and ESR (rs =.42, p <.001). Ratings of depression were positively and significantly related to ratings of sickness behavior and anxiety (β =.32 and β =.40, respectively), explaining 49 % of the total variance in depression ratings. Insomnia was positively and significantly related to sickness behavior (β =.37) explaining 31 % of the total variance in insomnia ratings. Inflammatory biomarkers, however, did not contribute significantly to the models.

CONCLUSIONS

Participants reported high levels of symptoms, yet the associations between these ratings and the inflammatory biomarkers were either absent or weak. Also, despite high levels of self-reported sickness behavior, overall the inflammatory status remained within the normal range. Ratings of sickness behavior contributed more than inflammatory markers in explaining ratings of depression and insomnia. The present results point to the complexity of chronic pain, and the challenges of identifying biomarkers that explain symptomatology.

Remote dried blood spot collection for inflammatory markers in older adults is feasible, reliable, and valid

Dried blood spots (DBS) provide a minimally invasive method to assess inflammatory markers and can be collected remotely at-home or in-person in the lab. However, there is a lack of methodological information comparing these different collection methods and in older adults. We investigated the feasibility (including adherence, yield, quality, and participant preferences) and measurement properties (reliability, validity) of remotely collected DBS inflammatory markers in older adults. Participants (N = 167, mean age = 72, range: 60-96 years) collected their own DBS (finger prick on filter paper) during three remote interviews over ∼ 6 months. Within 4-5 days on average of their last remote interview, a subset of 41 participants also attended an in-person lab visit that included a researcher-collected DBS sample, venous blood draw, and survey to assess participant preferences of DBS collection. DBS and venous blood were assayed for CRP, IL-6, and TNF-α. Adherence: 98% of expected DBS samples (493 out of 501) were completed and mailed back to the lab. Yield: 97% of DBS samples were sufficient for all assays. Quality: On average, 0.80 fewer optimal spots (60uL of blood that filled the entire circle) were obtained remotely vs. in-person (p = 0.013), but the number of useable or better spots (at least 30-40uL of blood) did not differ (p = 0.89). Preference: A slight majority of participants (54%) preferred in-person DBS collection. Reliability: DBS test-retest reliabilities were good: CRP (ICC = 0.74), IL-6 (ICC = 0.76), and TNF-α (ICC = 0.70). Validity: Inflammatory levels from DBS correlated strongly with levels from venous blood (r = 0.60-0.99) and correlated as expected with sociodemographic and physical health and function variables. Older adults can remotely collect their own DBS to acquire reliable and valid inflammatory data. Remote DBS collection is highly feasible and may allow for inflammatory markers to be assessed in larger, more representative samples than are possible with lab- or clinic-based research designs.

Serum cytokine and inflammatory markers in individuals with heroin use disorder: potential biomarkers for diagnosis and disease severity

Opioid use disorders cause major morbidity and mortality, and there is a pressing need for novel mechanistic targets and biomarkers for diagnosis and prognosis. Exposure to mu-opioid receptor (MOR) agonists causes changes in cytokine and inflammatory protein networks in peripheral blood, and also in brain glia and neurons. Individuals with heroin use disorder (iHUD) show dysregulated levels of several cytokines in blood. However, there is limited data on a comprehensive panel of such markers in iHUD versus healthy controls (HC), especially as a multi-target biomarker. We used a validated proximity extension assay for relative quantification of 92 cytokines and inflammatory proteins in serum of iHUD on medication assisted therapy (MAT; n=21), versus HC (n=24). Twenty-nine targets showed significant group differences (primarily iHUD>HC), surviving multiple comparison correction (p=0.05). This included 19 members of canonical cytokine families, including specific chemokines, interleukins, growth factors, and tumor necrosis factor (TNF)-related proteins. For dimensionality reduction, data from these 19 cytokines were entered into a principal component (PC) analysis, and PC1 scores were iHUD>HC (p<0.0001). A receiver-operating characteristic (ROC) curve analysis yielded an AUROC=91.7% (p<0.0001). This PC1 score remained a positive predictor of being in the HUD group in a multivariable logistic regression, which included demographic/clinical variables. Overall, this study shows a panel of cytokines that differ significantly between iHUD and HC, and provides a multi-target "cytokine biomarker score" for potential diagnostic purposes, and examination of disease severity.

Taking biological rhythms into account: From study design to results reporting

Numerous physiological and behavioral processes in living organisms exhibit strong rhythmicity and are regulated within a 24-hour cycle. These include locomotor activity and sleep patterns, feeding-fasting cycles, hormone synthesis, body temperature, and even mood and cognitive abilities, all of which are segregated into different phases throughout the day. These processes are governed by the internal timing system, a hierarchical multi-oscillator structure conserved across all organisms, from bacteria to humans. Circadian rhythms have been seen across multiple taxonomic kingdoms. In mammals, a hierarchical internal timing system is comprised of so-called central and periphereal clocks. Although these rhythms are intrinsic, they are under environmental influences, such as seasonal temperature changes, photoperiod variations, and day-night cycles. Recognizing the existence of biological rhythms and their primary external influences is crucial when designing and reporting experiments. Neglecting these physiological variations may result in inconsistent findings and misinterpretations. Thus, here we propose to incorporate biological rhythms into all stages of human and animal research, including experiment design, analysis, and reporting of findings. We also provide a flowchart to support decision-making during the design process, considering biological rhythmicity, along with a checklist outlining key factors that should be considered and documented throughout the study. This comprehensive approach not only benefits the field of chronobiology but also holds value for various other research disciplines. The insights gained from this study have the potential to enhance the validity, reproducibility, and overall quality of scientific investigations, providing valuable guidance for planning, developing, and communicating scientific studies.

Effect of Amino Acid Supplementation on Iron Regulation after Endurance Exercise

The purpose of this study was to determine the effects of pre-exercise amino acid (AA) supplementation on post-exercise iron regulation. Ten healthy males participated under two different sets of conditions in a randomized, double-blind, crossover design with a washout period of at least 21 days. Participants received either an AA supplement or placebo (PLA) for five consecutive days (4 g/dose, 3 doses/day). On the sixth day, participants ran on a treadmill for 60 min at 70% of maximal oxygen consumption (V˙O2max). Venous blood samples were collected before (baseline), immediately after, and 1 and 3 h after exercise. The serum hepcidin levels increased significantly 3 h post-exercise in both trials when compared to the baseline (p < 0.001), but the levels were not different between trials. The plasma interleukin-6 (IL-6) level significantly increased immediately after exercise compared to the baseline (p < 0.001) and was significantly higher in the AA trial than in the PLA trial (p = 0.014). Moreover, the exercise-induced increase in serum glycerol level was significantly higher in the AA trial (21.20 ± 3.98 mg/L) than in the PLA trial (17.28 ± 4.47 mg/L, p = 0.017). No significant differences were observed between the AA and PLA trials for serum iron, ferritin, and total ketone body levels (p > 0.05). In conclusion, five days of AA supplementation augmented exercise-induced increases in IL-6 and glycerol in healthy males. However, it did not affect post-exercise iron status or regulation.

Early Human Pathophysiological Responses to Exertional Hypobaric Decompression Stress

INTRODUCTION: Consistent blood biomarkers of hypobaric (altitude) decompression stress remain elusive. Recent laboratory investigation of decompression sickness risk at 25,000 ft (7620 m) enabled evaluation of early pathophysiological responses to exertional decompression stress.METHODS: In this study, 15 healthy men, aged 20-50 yr, undertook 2 consecutive (same-day) ascents to 25,000 ft (7620 m) for 60 and 90 min, breathing 100% oxygen, each following 1 h of prior denitrogenation. Venous blood was sampled at baseline (T0), immediately after the second ascent (T8), and next morning (T24). Analyses encompassed whole blood hematology, endothelial microparticles, and soluble markers of cytokine response, endothelial function, inflammation, coagulopathy, oxidative stress, and brain insult, plus cortisol and creatine kinase.RESULTS: Acute hematological effects on neutrophils (mean 72% increase), eosinophils (40% decrease), monocytes (37% increase), and platelets (7% increase) normalized by T24. Consistent elevation (mean five-fold) of the cytokine interleukin-6 (IL-6) at T8 was proinflammatory and associated with venous gas emboli (microbubble) load. Levels of C-reactive protein and complement peptide C5a were persistently elevated at T24, the former by 100% over baseline. Additionally, glial fibrillary acidic protein, a sensitive marker of traumatic brain injury, increased by a mean 10% at T24.CONCLUSIONS: This complex composite environmental stress, comprising the triad of hyperoxia, decompression, and moderate exertion at altitude, provoked pathophysiological changes consistent with an IL-6 cytokine-mediated inflammatory response. Multiple persistent biomarker disturbances at T24 imply incomplete recovery the day after exposure. The elevation of glial fibrillary acidic protein similarly implies incomplete resolution following recent neurological insult.Connolly DM, Madden LA, Edwards VC, D'Oyly TJ, Harridge SDR, Smith TG, Lee VM. Early human pathophysiological responses to exertional hypobaric decompression stress. Aerosp Med Hum Perform. 2023; 94(10):738-749.

Factors Influencing the Hepcidin Response to Exercise: An Individual Participant Data Meta-analysis

BACKGROUND

Hepcidin, the master iron regulatory hormone, has been shown to peak 3-6 h postexercise, and is likely a major contributor to the prevalence of iron deficiency in athletes. Although multiple studies have investigated the hepcidin response to exercise, small sample sizes preclude the generalizability of current research findings.

OBJECTIVE

The aim of this individual participant data meta-analysis was to identify key factors influencing the hepcidin-exercise response.

METHODS

Following a systematic review of the literature, a one-stage meta-analysis with mixed-effects linear regression, using a stepwise approach to select the best-fit model, was employed.

RESULTS

We show that exercise is associated with a 1.5-2.5-fold increase in hepcidin concentrations, with pre-exercise hepcidin concentration accounting for ~ 44% of the variance in 3 h postexercise hepcidin concentration. Although collectively accounting for only a further ~ 3% of the variance, absolute 3 h postexercise hepcidin concentrations appear higher in males with lower cardiorespiratory fitness and higher pre-exercise ferritin levels. On the other hand, a greater magnitude of change between the pre- and 3 h postexercise hepcidin concentration was largely attributable to exercise duration (~ 44% variance) with a much smaller contribution from VO2max, pre-exercise ferritin, sex, and postexercise interleukin-6 (~ 6% combined). Although females tended to have a lower absolute 3 h postexercise hepcidin concentration [1.4 nmol·L-1, (95% CI [- 2.6, - 0.3]), p = 0.02] and 30% less change (95% CI [-54.4, - 5.1]), p = 0.02) than males, with different explanatory variables being significant between sexes, sample size discrepancies and individual study design biases preclude definitive conclusions.

CONCLUSION

Our analysis reveals the complex interplay of characteristics of both athlete and exercise session in the hepcidin response to exercise and highlights the need for further investigation into unaccounted-for mediating factors.

Glycoprotein acetyls and depression: Testing for directionality and potential causality using longitudinal data and Mendelian randomization analyses

BACKGROUND

Inflammation is associated with depression, but causality remains unclear. We investigated potential causality and direction of effect between inflammation and depression.

METHODS

Using data from the ALSPAC birth cohort (n = 4021; 42.18 % male), we used multivariable regression to investigate bidirectional longitudinal associations of GlycA and depression and depression symptoms, assessed at ages 18y and 24y. We used two-sample Mendelian randomization (MR) to investigate potential causality and directionality. Genetic variants for GlycA were obtained from UK Biobank (UKB) (N = 115,078); for depression from the Psychiatric Genomics Consortium and UKB (N = 500,199); and for depressive symptoms (N = 161,460) from the Social Science Genetic Association Consortium. In addition to the Inverse Variance Weighted method, we used sensitivity analyses to strengthen causal inference. We conducted multivariable MR adjusting for body mass index (BMI) due to known genetic correlation between inflammation, depression and BMI.

RESULTS

In the cohort analysis, after adjusting for potential confounders we found no evidence of associations between GlycA and depression symptoms score or vice versa. We observed an association between GlycA and depression (OR = 1∙18, 95 % CI: 1∙03-1∙36). MR suggested no causal effect of GlycA on depression, but there was a causal effect of depression on GlycA (mean difference in GlycA = 0∙09; 95 % CI: 0∙03-0∙16), which was maintained in some, but not all, sensitivity analyses.

LIMITATIONS

The GWAS sample overlap could incur bias.

CONCLUSION

We found no consistent evidence for an effect of GlycA on depression. There was evidence that depression increases GlycA in the MR analysis, but this may be confounded/mediated by BMI.

Interpersonal Life Stress and Inflammatory Reactivity as Prospective Predictors of Suicide Attempts in Adolescent Females

Adolescents' suicidal behavior frequently is preceded by interpersonal stress, but not all who experience distress attempt to end their lives. Recent theories have posited individual differences in stress-related inflammatory reactivity may be associated with psychopathology risk; this study examined inflammatory reactivity as a moderator of the prospective association between interpersonal stress and adolescents' suicidal behavior. Participants included 157 at-risk adolescent females (ages 12 to 16 years) and assessed individual differences in proinflammatory cytokine responses to a brief laboratory-based social stressor, both interpersonal and non-interpersonal life events, and suicidal behavior over an 18-month follow-up period. Measuring levels of the key proinflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) before and after an experimentally-induced social stressor, results revealed that blunted cytokine reactivity heightened the effect of high interpersonal stress exposure on risk for suicidal behaviors over the subsequent 9 months. Significant effects were not revealed for non-interpersonally themed stress. Finding highlight the urgent need for more research examining inflammation reactivity among adolescents.

Associations between blood inflammatory markers and bone mineral density and strength in the femoral neck: findings from the MIDUS II study

Chronic and systematic inflammation have been related to increased risks of osteopenia and related fracture. However, studies concerning the association between low-grade inflammation and the bone mineral density (BMD) and strength of the femoral neck are still few and inconsistent. This study aimed to examine the relationships between blood inflammatory biomarkers and BMD and femoral neck strength in an adult-based cohort. We retrospectively analyzed a total of 767 participants included in the Midlife in the United States (MIDUS) study. The blood levels of inflammatory markers, including interleukin-6 (IL6), soluble IL-6 receptor, IL-8, IL-10, TNF-α and C-reactive protein (CRP), in these participants were measured, and their associations with the BMD and strength of the femoral neck were determined. We analyzed these 767 subjects with data concerning the BMD, bending strength index (BSI), compressive strength index (CSI), and impact strength index (ISI) in the femoral neck and inflammatory biomarkers. Importantly, our results suggest that strongly negative associations exist between the blood soluble IL6 receptor levels and the BMD (per SD change, Sβ = -0.15; P < 0.001), CSI (per SD change, Sβ = -0.07; P = 0.039), BSI (per SD change, Sβ = -0.07; P = 0.026), and ISI (per SD change, Sβ = -0.12; P < 0.001) in the femoral neck after adjusting for age, gender, smoked cigarettes regularly, number of years drinking, BMI and regular exercise. However, the inflammatory biomarkers, including blood IL-6 (per SD change, Sβ = 0.00; P = 0.893), IL-8 (per SD change, Sβ = -0.00; P = 0.950), IL-10 (per SD change, Sβ = -0.01; P = 0.854), TNF-α (per SD change, Sβ = 0.04; P = 0.260) and CRP (per SD change, Sβ = 0.05; P = 0.137), were not strongly associated with the BMD in the femoral neck under the same conditions. Similarly, there was no significant difference in the relationships between the inflammatory biomarkers (IL-6, IL-8, IL-10, TNF-α and CRP) and the CSI, BSI, and ISI in the femoral neck. Interestingly, in concomitant inflammation-related chronic diseases, only arthritis affected the soluble IL-6 receptor and the CIS (interaction P = 0.030) and SIS (interaction P = 0.050) in the femoral neck. In this cross-sectional analysis, we only observed that high blood levels of soluble IL-6 receptor were strongly associated with reduced BMD and bone strength in the femoral neck. The independent associations between the other inflammatory indicators, including IL-6, IL-8, IL-10, TNF-α and CRP, and the BMD and femoral neck strength in an adult-based cohort were not significant.

Rapid Activation of Neuroinflammation in Stroke: Plasma and Extracellular Vesicles Obtained on a Mobile Stroke Unit

BACKGROUND

Neuroinflammation is ubiquitous in acute stroke and worsens outcome. However, the precise timing of the inflammatory response is unknown, hindering the design of acute anti-inflammatory therapeutic interventions. We sought to identify the onset of the neuroinflammatory cascade using a mobile stroke unit.

METHODS

The study is a proof-of-concept, cohort investigation of ultra-early blood- and extracellular vesicle-derived markers of neuroinflammation and outcome in acute stroke. Blood was obtained, prehospital, on an mobile stroke unit. Outcomes were biomarker concentrations, modified Rankin Scale score, and National Institutes of Health Stroke Scale score.

RESULTS

Forty-one adults were analyzed, including 15 patients treated on the mobile stroke unit between August 2021 and April 2022, and 26 healthy controls to establish biomarker reference levels. Median patient age was 74 (range, 36-97) years, 60% were female, and 80% White. Ten (67%) were diagnosed as stroke, with 8 (53%) confirmed and 2 likely transient ischemic attack or stroke averted by thrombolysis; 5 were stroke mimics. For strokes, median initial National Institutes of Health Stroke Scale score was 11 (range, 4-19) and 6 (75%) received tPA (tissue-type plasminogen activator). Blood was obtained a median of 58 (range, 36-133) minutes after symptom onset. Within 36 minutes after stroke, plasma IL-6 (interleukin-6), neurofilament light chain, UCH-L1 (ubiquitin C-terminal hydrolase L1), and GFAP (glial fibrillary acidic protein) were elevated by as much as 10 times normal. In EVs, MMP-9 (matrix metalloproteinase-9), CXCL4 (chemokine (C-X-C motif) ligand 4), CRP (C-reactive protein), IL-6, OPN (osteopontin), and PECAM1 (platelet and endothelial cell adhesion molecule 1) were elevated. Inflammatory markers increased rapidly in the first 2 hours and continued rising for 24 hours.

CONCLUSIONS

The neuroinflammatory cascade was found to be activated within 36 to 133 minutes after stroke and progresses rapidly. This is earlier than observed previously in humans and suggests injury from neuroinflammation occurs faster than had been surmised. These findings could inform development of acute immunomodulatory stroke therapies and lead to new diagnostic tools and improved outcomes.

Dose-response effects of periodic physical activity breaks on the chronic inflammatory risk associated with sedentary behavior in high- and upper-middle income countries: A systematic review and meta-analysis

BACKGROUND AND AIMS

Though moderate-vigorous physical activity (MVPA) is speculated to mitigate the inflammatory risk associated with sedentary behavior, only a fraction of the global population meets the recommended weekly dose of MVPA. More individuals indulge in bouted and sporadic light-intensity physical activity (LIPA) that occurs throughout the typical day. However, the anti-inflammatory effects of LIPA or MVPA breaks during prolonged sitting remains unclear.

METHODS

A systematic search was done on six peer-reviewed databases through January 27th, 2023. Two authors independently screened the citations for eligibility, and risk of bias and performed a meta-analysis.

RESULTS

The included studies originated from high and upper - middle income countries. Observational studies of SB interruptions with LIPA showed favourable effects on inflammatory mediators such as higher levels of adiponectin (odds ratio, OR = +0.14; p = 0.02). However, these findings are not supported by the experimental studies. Experimental studies reported non-significant increase in cytokines including IL-1β (standardised mean difference, SMD = 0.11 pg/ml; p = 0.29) and IL-6 (SMD = 0.19 pg/ml; p = 0.46) after interrupting sitting with LIPA breaks. But these LIPA breaks were found to reduce C-reactive protein (SMD = - 0.50 mg/dl; p = 0.85) and IL-8 levels (SMD = -0.08 pg/ml; p = 0.34) but did not reach statistical significance.

CONCLUSION

Interrupting prolonged sitting time with LIPA breaks shows promise for preventing the inflammatory effects associated with prolonged bouts of daily sitting, though the evidence remains in infancy and limited to high- and upper-middle income countries.

Association between fatigue and cytokine profiles in patients with ischemic stroke

Background

Chronic fatigue is a common symptom after a stroke. Studies suggested that chronic fatigue is caused by inflammatory or immunological processes but data are limited and contradictory. Thus, the present study aimed to identify specific biomarkers associated with fatigue in post-stroke patients and replicated the findings in a population-based study.

Methods

We investigated associations between 39 circulating biomarkers of inflammation and fatigue in 327 patients after an ischemic stroke included in the Stroke Cohort Augsburg (SCHANA) study and the "Metabolism, Nutrition and Immune System in Augsburg" (MEIA) study (n = 140). The Fatigue Assessment Scale (FAS) was used to assess the severity of fatigue. The serum concentrations of the biomarkers were measured using the Bio-Plex Pro™ Human Cytokine Screening Panel (Bio-Rad, USA). Multiple linear regression models adjusted for possible confounders were used to examine associations.

Results

In patients with stroke, SCGFb was inversely associated [-1.67, 95% confidence interval (CI) (-3.05; -0.29) p = 0.018], and in healthy subjects, G-CSF was positively associated [1.56, 95% CI (0.26; 2.87), p = 0.020] with an increasing FAS-score, while SCF was positively related in both samples [1.84, 95% CI (0.27; 3.42), p = 0.022 and 1.40, 95% CI (0.29; 2.52), p = 0.015]. However, after correction for multiple testing, all of these associations lost statistical significance.

Conclusion

The present findings suggested an association between the growth factor SCF and fatigue. Future research on cytokines as possible markers of fatigue should focus on a longitudinal design including a sufficiently large number of study participants to enable testing associations between certain cytokines and sub-groups of chronic fatigue.

Establishment of quantitative indicators for an efficient treatment on masticatory muscle pain

BACKGROUND

Although several studies have investigated effective treatments for masticatory muscle pain (MMP), no unified conclusion has been drawn regarding the effectiveness of these treatments.

OBJECTIVES

This study aimed to define quantitative indicators for predicting the outcome of MMP treatment.

MATERIALS AND METHODS

In total, patients aged 20-70 years were recruited and divided into the MMP (n = 24) and control (n = 36) groups, based on the presence of MMP according to the Diagnostic Criteria for Temporomandibular Disorders. At pretreatment, the MMP group was assessed using quantitative indicators such as subjective pain levels, pain duration, graded chronic pain scale (GCPS), and perceived stress scale (PSS). Salivary alpha-amylase (sAA) and interleukin-6 (IL-6) levels were analyzed. The masticatory muscle palpation score and the range of mouth opening were measured. At posttreatment, subjective pain levels, mouth opening, and treatment/medication duration were examined. The PSS and sAA levels were assessed in the control group.

RESULTS

sAA levels in the MMP group were significantly higher than those in the control group (p < .05). The masseter muscle palpation score (MPS) showed a positive correlation with IL-6 levels (ρ = 0.503, p < .05) and a negative correlation with nonsteroidal anti-inflammatory drug (NSAID) treatment period (ρ = -0.462, p < .05). The temporalis muscle palpation score (TPS) was positively correlated with pain duration and GCPS grade (ρ = 0.483, p < .05, and ρ = 0.445, p < .05, respectively).

CONCLUSIONS

Treatment with NSAIDs was effective in the MMP group with high MPS and IL-6 levels, but not in the MMP group with high TPS, pain duration, and GCPS grade.

Time to run: Late rather than early exercise training in mice remodels the gut microbiome and reduces atherosclerosis development

The metabolic and inflammatory processes that are implicated in the development of cardiovascular diseases are under control of the biological clock. While skeletal muscle function exhibits circadian rhythms, it is unclear to what extent the beneficial health effects of exercise are restricted to unique time windows. We aimed to study whether the timing of exercise training differentially modulates the development of atherosclerosis and elucidate underlying mechanisms. We endurance-trained atherosclerosis-prone female APOE*3-Leiden.CETP mice fed a Western-type diet, a well-established human-like model for cardiometabolic diseases, for 1 h five times a week for 4 weeks either in their early or in their late active phase on a treadmill. We monitored metabolic parameters, the development of atherosclerotic lesions in the aortic root and assessed the composition of the gut microbiota. Late, but not early, exercise training reduced fat mass by 19% and the size of early-stage atherosclerotic lesions by as much as 29% compared to sedentary animals. No correlation between cholesterol exposure and lesion size was evident, as no differences in plasma lipid levels were observed, but circulating levels of the pro-inflammatory markers ICAM-1 and VCAM-1 were reduced with late exercise. Strikingly, we observed a time-of-day-dependent effect of exercise training on the composition of the gut microbiota as only late training increased the abundance of gut bacteria producing short-chain fatty acids with proposed anti-inflammatory properties. Together, these findings indicate that timing is a critical factor to the beneficial anti-atherosclerotic effects of exercise with a great potential to further optimize training recommendations for patients.

Meta-analyses reveal serum or plasma Interleukin-6 as a biomarker for malignant ovarian neoplasia

BACKGROUND

Interleukin-6 (IL-6) has been implicated in various malignancies, including ovarian cancer. However, mixed results have been observed regarding IL-6 levels in different ovarian conditions. This meta-analysis was performed to determine IL-6 levels in the peritoneal fluid and peripheral blood among patients with various adnexal masses.

METHODS

Most popular English databases were searched using a predefined search formula. All studies comparing IL-6 levels in plasma, serum or peritoneal fluid of patients with benign tumors, ovarian neoplasms, and healthy controls were included based on inclusion and exclusion criteria.

RESULTS

5953 patients from 22 primary publications raging from 1994 to 2021 were included in the meta-analyses. A pooled IL-6 Mean Difference (MD) of 41 pg/mL for malignant tumors compared to benign ones, with a Confidence Interval (CI) between 19.8 and 62.2, a Z-score of 3.79, and statistical significance with a p = 0.0002 was observed. Pooled results for healthy versus benign ovarian conditions showed an MD of 5.45 pg/mL for serum or plasma IL-6 measurements in favor of benign tumors (CI:0.66-10.25, Z = 2.23 and p = 0.03). The analysis showed an MD for IL-6 levels of 19.59 pg/mL for healthy controls versus malignant ovarian tumors. Peritoneal fluid measurements regarding IL-6's levels showed no significant difference between benign or malignant masses.

DISCUSSION/CONCLUSIONS

Higher levels of plasma or serum IL-6 in ovarian neoplasia patients compared to benign conditions or healthy controls identify IL-6 as a discerning factor between benign or malignant ovarian tumors and a potential biomarker for ovarian malignancy.

A systematic review and meta-analysis of the stability of peripheral immune markers in healthy adults

Peripheral immune markers are widely used to predict risk for inflammatory disease. However, whether single assessments of inflammatory biomarkers represent stable individual differences remains unclear. We reviewed 50 studies (N = 48,674; 57 % male; mean age 54 (range 13-79) years) that assessed markers of inflammation on >1 occasion, with time between measures ranging from 24 h to 7+ years. Separate random effects meta-analyses were conducted for each inflammatory marker and time interval. Markers that had broad coverage across most time intervals included C-reactive protein (CRP; k = 37), interleukin (IL)-6 (k = 22), TNF-α (k = 10), and fibrinogen (Fg; k = 9). For CRP, IL-6, and TNF-α, stability estimates generally decreased with time, with strong to moderate stability over intervals <6 months (r's = 0.80-0.61), modest to moderate stability over 6 months - 3 years (r's = 0.60-0.51), and low stability for >3 years (r's = 0.39-0.30). Estimates were less reliable for Fg for time intervals ≤ 3 years although they generally followed the same pattern; more reliable findings suggested greater stability for Fg than other markers for intervals >3 years (r = 0.53). These findings suggest that single measures of inflammatory biomarkers may be an adequate index of stable individual differences in the short term (<6 months), with repeated measures of inflammatory biomarkers recommended over intervals ≥ 6 months to 3 years, and absolutely necessary over intervals >3 years to reliably identify stable individual differences in health risk. These findings are consistent with stability estimates and clinical recommendations for repeated measurement of other cardiovascular measures of risk (e.g., blood lipids, blood pressure).

Advanced development and mechanism of sepsis-related acute respiratory distress syndrome

The introduction of the Sepsis 3.0 guidelines in 2016 improved our understanding of sepsis diagnosis and therapy. Personalized treatment strategies and nursing methods for sepsis patients are recommended in the "Save Sepsis Campaign" in 2021. However, mortality in sepsis patients remains high. Patients with sepsis-related acute respiratory distress syndrome account for around 30% of them, with fatality rates ranging from 30 to 40%. Pathological specimens from individuals with sepsis-related ARDS frequently demonstrate widespread alveolar damage, and investigations have revealed that pulmonary epithelial and pulmonary endothelial injury is the underlying cause. As a result, the purpose of this work is to evaluate the mechanism and research progress of pulmonary epithelial and pulmonary endothelial damage in sepsis-related ARDS, which may provide new directions for future research, diagnosis, and therapy.

Dynamic behavior of cell-free mitochondrial DNA in human saliva

Mitochondria contain their own genome that can be released in multiple biofluids such as blood and cerebrospinal fluid, as cell-free mitochondrial DNA (cf-mtDNA). In clinical studies, blood cf-mtDNA predicts mortality and higher cf-mtDNA levels are associated with mental and physical stress. However, the dynamics of cf-mtDNA has not been defined, and whether it can be measured non-invasively like other neuroendocrine markers in saliva has not been examined. Here we report cf-mtDNA in human saliva and establish its natural within-person dynamic behavior across multiple weeks. In a small proof-of-principle cohort of healthy adults, we first develop an approach to rapidly quantify salivary cf-mtDNA without DNA isolation, and demonstrate the existence of salivary cf-mtDNA. We then deploy this approach to perform an intensive repeated-measures analysis of two healthy men studied at 4 daily timepoints over 53-60 consecutive days (n = 212-220 observations each) with parallel measures of steroid hormones, self-reported daily mood, and health-related behaviors. Salivary cf-mtDNA exhibited a robust awakening response reaching up to two orders of magnitude 30-45 min after awakening, varied from day-to-day, and moderately correlated with the cortisol awakening response. In exploratory analyses, no consistent association with self-reported daily mood/health-related behaviors were found, although this requires further examination in future studies. Dynamic variation in cf-mtDNA was inversely related with salivary interleukin 6 (IL-6), inconsistent with a pro-inflammatory effect of salivary cf-mtDNA. The highly dynamic behavior of salivary cf-mtDNA opens the door to non-invasive studies examining the relevance of mtDNA signaling in relation to human health.

CC-99677, a novel, oral, selective covalent MK2 inhibitor, sustainably reduces pro-inflammatory cytokine production

BACKGROUND

Mitogen-activated protein kinase (MAPK)-activated protein kinase-2 (MK2) is activated downstream of p38 MAPK and regulates stability of mRNAs encoding inflammatory cytokines. CC-99677 is a novel, irreversible, covalent MK2 inhibitor under development for the treatment of ankylosing spondylitis (AS) and other inflammatory diseases. As part of a phase I clinical trial to assess safety and tolerability, we evaluated target engagement, pharmacokinetics, and pharmacodynamics of CC-99677.

METHODS

The MK2 inhibitor CC-99677 was evaluated for its effect on cytokine expression in vitro in peripheral blood mononuclear cells (PBMCs) from healthy donors and patients with a definitive AS diagnosis. A novel in vitro model was developed to compare the potential for tachyphylaxis of CC-99677 and p38 inhibitors in THP-1 cells. The effect of CC-99677 on tristetraprolin (TTP) and cytokine mRNA was assessed in stimulated human monocyte-derived macrophages. In a first-in-human study, thirty-seven healthy volunteers were randomly assigned to daily oral doses of CC-99677 or placebo, and blood was collected at pre-specified time points before and after dosing. CC-99677 concentrations were assessed in the plasma, and CC-99677 binding to MK2 was evaluated in PBMCs. Ex vivo stimulation of the whole blood was conducted from participants in the first-in-human study to assess the pharmacodynamic effects.

RESULTS

In vitro, CC-99677 inhibited tumor necrosis factor (TNF), interleukin (IL)-6, and IL-17 protein production in samples of monocytes and macrophages from AS patients and healthy volunteers via an mRNA-destabilization mechanism. In the in vitro model of tachyphylaxis, CC-99677 showed a differentiated pattern of sustained TNF protein inhibition compared with p38 inhibitors. CC-99677 reduced TTP phosphorylation and accelerated the decay of inflammatory cytokine mRNA in lipopolysaccharide-stimulated macrophages. Administration of CC-99677 to healthy volunteers was safe and well-tolerated, with linear pharmacokinetics and sustained reduction of ex vivo whole blood TNF, IL-6, and chemokine synthesis.

CONCLUSIONS

CC-99677 inhibition of MK2 is a promising approach for the treatment of inflammatory diseases and may overcome the limitations of p38 MAPK inhibition.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03554993 .

Louis EK, Przybelski SA, Morgenthaler TI, Machulda MM, Boeve BF, Petersen RC, Jack CR, Graff-Radford J, Vemuri P, Mielke MM. Sleepiness in Cognitively Unimpaired Older Adults Is Associated With CSF Biomarkers of Inflammation and Axonal Integrity

Introduction

Sleepiness has been associated with cognitive decline and dementia in the elderly. Older adults with excessive daytime sleepiness appear to be more vulnerable to longitudinal amyloid PET accumulation before the onset of the dementia. However, it remains unclear whether sleepiness is similarly associated with other biomarkers of Alzheimer's disease (AD), axonal integrity, and inflammation, which may also contribute to neurodegeneration and cognitive decline.

Methods

In this cross-sectional analysis, we identified 260 cognitively unimpaired adults (>60 years) from the Mayo Clinic Study of Aging, a population-based cohort from Olmsted County (MN), who underwent CSF quantification of AD biomarkers (Aβ42, p-tau, p-tau/Aβ42) in addition to at least one of the following biomarkers [neurofilament light chain (NfL) interleukin-6 (IL-6), IL-10, and tumor necrosis factor-α (TNF-α)]. We fit linear regression models to assess associations between sleepiness, as measured by the Epworth Sleepiness Scale (ESS), and CSF biomarkers, controlling for age, sex, APOε4 status, body mass index, hypertension, dyslipidemia, and prior diagnosis of obstructive sleep apnea.

Results

Higher ESS scores were associated with higher CSF IL-6 and NfL, but not with the other CSF biomarkers. For every ESS score point increase, there was a 0.009 ([95% CI 0.001-0.016], p = 0.033) increase in the log of IL-6 and 0.01 ([95% CI 0.002-0.018], p = 0.016) increase in the log of NfL. A sensitivity analysis showed an association between ESS scores and log of p-tau/Aβ42 only in participants with an abnormal ratio (>0.023), highly predictive of amyloid positivity. For every ESS score point increase, there was a 0.006 ([95% CI 0.001-0.012], p = 0.021) increase in the log of CSF p-tau/Aβ42.

Conclusion

Sleepiness was associated with greater CSF IL-6 and NfL levels, which could contribute to neurodegeneration or alternatively cause sleepiness. Higher NfL levels may result from sleep disruption and/or contribute to sleepiness via disturbed connectivity or damage to wake-promoting centers. Associations between sleepiness and p-tau/Aβ42 in participants with abnormal ratio suggest that amyloid positivity contributes to vulnerability to sleep disturbance, which may further amyloid accumulation in a feed-forward loop process. Prospective studies of these markers are needed to determine cause-effect relationships between these associations.

Sequential Submaximal Training in Elite Male Rowers Does Not Result in Amplified Increases in Interleukin-6 or Hepcidin

Previous research investigating single bouts of exercise have identified baseline iron status and circulating concentrations of interleukin-6 (IL-6) as contributors to the magnitude of postexercise hepcidin increase. The current study examined the effects of repeated training bouts in close succession on IL-6 and hepcidin responses. In a randomized, crossover design, 16 elite male rowers completed two trials, a week apart, with either high (1,000 mg) or low (<50 mg) calcium pre-exercise meals. Each trial involved two, submaximal 90-min rowing ergometer sessions, 2.5 hr apart, with venous blood sampled at baseline; pre-exercise; and 0, 1, 2, and 3 hr after each session. Peak elevations in IL-6 (approximately 7.5-fold, p < .0001) and hepcidin (approximately threefold, p < .0001) concentrations relative to baseline were seen at 2 and 3 hr after the first session, respectively. Following the second session, concentrations of both IL-6 and hepcidin remained elevated above baseline, exhibiting a plateau rather than an additive increase (2 hr post first session vs. 2 hr post second session, p = 1.00). Pre-exercise calcium resulted in a slightly greater elevation in hepcidin across all time points compared with control (p = .0005); however, no effect on IL-6 was evident (p = .27). Performing multiple submaximal training sessions in close succession with adequate nutritional support does not result in an amplified increase in IL-6 or hepcidin concentrations following the second session in male elite rowers. Although effects of calcium intake require further investigation, athletes should continue to prioritize iron consumption around morning exercise prior to exercise-induced hepcidin elevations to maximize absorption.

A systematic review examining the relationship between cytokines and cachexia in incurable cancer

Cancer cachexia is an unmet clinical need that affects more than 50% of patients with cancer. The systemic inflammatory response, which is mediated by a network of cytokines, has an established role in the genesis and maintenance of cancer as well as in cachexia; yet, the specific role of the cytokine milieu in cachexia requires elucidation. This systematic review aims to examine the relationship between cytokines and the cachexia syndrome in patients with incurable cancer. The databases MEDLINE, EMBASE, CINAHL, CENTRAL, PsycINFO, and Web of Science were searched for studies published between 01/01/2004 and 06/01/2020. Included studies measured cytokines and their relationship with cachexia and related symptoms/signs in adults with incurable cancer. After title screening (n = 5202), the abstracts (n = 1264) and the full-text studies (n = 322) were reviewed independently by two authors. The quality assessment of the selected papers was conducted using the modified Downs and Black checklist. Overall, 1277 patients with incurable cancer and 155 healthy controls were analysed in the 17 eligible studies. The mean age of the patients was 64 ± 15 (mean ± standard deviation). Only 34% of included participants were female. The included studies were assessed as moderate-quality to high-quality evidence (mean quality score: 7.8; range: 5-10). A total of 31 cytokines were examined in this review, of which interleukin-6 (IL-6, 14 studies) and tumour necrosis factor-α (TNF-α, 12 studies) were the most common. The definitions of cachexia and the weight-loss thresholds were highly variable across studies. Although the data could not be meta-analysed due to the high degree of methodological heterogeneity, the findings were discussed in a systematic manner. IL-6, TNF-α, and IL-8 were greater in cachectic patients compared with healthy individuals. Also, IL-6 levels were higher in cachectic participants as opposed to non-cachectic patients. Leptin, interferon-γ, IL-1β, IL-10, adiponectin, and ghrelin did not demonstrate any significant difference between groups when individuals with cancer cachexia were compared against non-cachectic patients or healthy participants. These findings suggest that a network of cytokines, commonly IL-6, TNF-α, and IL-8, are associated with the development of cachexia. Yet, this relationship is not proven to be causative and future studies should opt for longitudinal designs with consistent methodological approaches, as well as adequate techniques for analysing and reporting the results.

Sleep, Positive Affect, and Circulating Interleukin-6 in Women With Temporomandibular Joint Disorder

OBJECTIVE

Systemic inflammation is commonly observed in idiopathic chronic pain conditions, including temporomandibular joint disorder (TMD). Trait positive affect (PA) is associated with lower inflammation in healthy controls, but those effects may be threatened by poor sleep. The associations between PA with proinflammatory cytokine activity and potential moderation by sleep in chronic pain are not known. We thus investigated the association between PA and circulating interleukin-6 (IL-6) and moderation of that association by sleep in a sample of women with TMD and sleep difficulties.

METHODS

Participants (n = 110) completed the insomnia severity index and provided blood samples at five intervals throughout an evoked pain testing session. They then completed a 14-day diary assessing sleep and affect, along with wrist actigraphy.

RESULTS

There was not a significant main effect of PA on resting or pain-evoked IL-6 (b = 0.04, p = .33). Diary total sleep time (b = -0.002, p = .008), sleep efficiency (b = -0.01, p = .005), sleep onset latency (b = 0.006, p = .010), and wake after sleep onset (b = 0.003, p = .033) interacted with PA to predict IL-6, such that PA inversely predicted IL-6 at higher levels of total sleep time and sleep efficiency and at lower levels of sleep onset latency and wake after sleep onset. Surprisingly, when sleep was poor, PA predicted greater IL-6.

CONCLUSIONS

The potential salutary effects of PA on resting IL-6 erode when sleep is poor, underscoring the importance of considering sleep in conceptual and intervention models of TMD.

Psychosomatic syndromes are associated with IL-6 pro-inflammatory cytokine in heart failure patients

Psychosomatic syndromes have emerged as an important source of comorbidity in cardiac patients and have been associated with increased risk for adverse outcomes in patients with heart failure (HF). Understanding of the mechanisms underlying this connection is limited, however immune activity represents a possible pathway. While there have been numerous studies connecting immune activity to psychosomatic psychopathology, there is a lack of research on patients with HF. We examined forty-one consecutive outpatients affected by HF. We assessed psychosomatic psychopathology using the Diagnostic Criteria for Psychosomatic Research (DCPR) and the Patient Health Questionnaire-15 (PHQ-15). The Psychosocial Index (PSI) was used for assessing stress and psychosocial dimensions. Depression was evaluated with Beck Depression Inventory-II (BDI-II). Circulating levels of proinflammatory cytokines IL-6 and TNF-alpha were ascertained. Univariate and multivariable regression models were used to test for associations between inflammatory cytokines and psychosomatic psychopathology (i.e., DCPR syndromes, PHQ-15) and psychological dimensions (i.e., BDI-II, PSI). A significant positive correlation was found between IL-6 levels and psychosomatic psychopathology even when controlling for any confounding variables (i.e., Body-mass index (BMI), New York Heart Association (NYHA) class, smoking habits, alcohol consumption, statin use, aspirin use, beta blockers use, age, and gender). In contrast, the associations between TNF-alpha levels were non-significant. These findings can contribute to research in support of a psychoneuroimmune connection between psychosomatic psychopathology and HF. Findings also suggest the possibility that elevated IL-6 levels are more relevant for the pathogenesis of psychosomatic syndromes than for depression in patients with HF.

Lifetime stressor exposure, systemic inflammation during pregnancy, and preterm birth among Black American women

Although Black American mothers and infants are at higher risk for morbidity and mortality than their White counterparts, the biological mechanisms underlying these phenomena remain largely unknown. To investigate the role that lifetime stressor exposure, perceived stressor severity, and systemic inflammatory markers might play, we studied how these factors were interrelated in 92 pregnant Black American women. We also compared inflammatory marker levels for women who did versus did not go on to give birth preterm. During the early third trimester, women completed the Stress and Adversity Inventory for Adults to assess the stressors they experienced over their lifetime. Women also provided blood samples for plasma interleukin (IL)-6, IL-8, IL-1β, and tumor necrosis factor (TNF)-α quantification. Preterm births were identified by medical record review. Controlling for relevant covariates, there were significant positive associations between average levels of both overall and acute perceived stressor severity and plasma IL-1β levels. Controlling for perceived stress at assessment and exposure to racial discrimination did not affect these results. Mediation models revealed that exposure to more chronic stressors was related to higher plasma IL-1β levels, as mediated by higher average levels of overall perceived stressor severity. Exposure to fewer acute stressors was related to higher plasma IL-1β levels, as mediated by higher average levels of acute perceived stressor severity. Finally, women who went on to give birth preterm had higher levels of plasma IL-6. These data thus highlight the potential importance of assessing and addressing lifetime stressor exposure among mothers before and during maternal-infant care.

A randomized, double-blind, placebo-controlled trial of intravenous alpha-1 antitrypsin for acute respiratory distress syndrome secondary to COVID-19

Background

Patients with severe coronavirus disease 2019 (COVID-19) develop a febrile pro-inflammatory cytokinemia with accelerated progression to acute respiratory distress syndrome (ARDS). Here we report the results of a phase 2, multicenter, randomized, double-blind, placebo-controlled trial of intravenous (IV) plasma-purified alpha-1 antitrypsin (AAT) for moderate to severe ARDS secondary to COVID-19 (EudraCT 2020-001391-15).

Methods

Patients (n = 36) were randomized to receive weekly placebo, weekly AAT (Prolastin, Grifols, S.A.; 120 mg/kg), or AAT once followed by weekly placebo. The primary endpoint was the change in plasma interleukin (IL)-6 concentration at 1 week. In addition to assessing safety and tolerability, changes in plasma levels of IL-1β, IL-8, IL-10, and soluble tumor necrosis factor receptor 1 (sTNFR1) and clinical outcomes were assessed as secondary endpoints.

Findings

Treatment with IV AAT resulted in decreased inflammation and was safe and well tolerated. The study met its primary endpoint, with decreased circulating IL-6 concentrations at 1 week in the treatment group. This was in contrast to the placebo group, where IL-6 was increased. Similarly, plasma sTNFR1 was substantially decreased in the treatment group while remaining unchanged in patients receiving placebo. IV AAT did not definitively reduce levels of IL-1β, IL-8, and IL-10. No difference in mortality or ventilator-free days was observed between groups, although a trend toward decreased time on ventilator was observed in AAT-treated patients.

Conclusions

In patients with COVID-19 and moderate to severe ARDS, treatment with IV AAT was safe, feasible, and biochemically efficacious. The data support progression to a phase 3 trial and prompt further investigation of AAT as an anti-inflammatory therapeutic.

Funding

ECSA-2020-009; Elaine Galwey Research Bursary.

Epidemiology of interleukin-6: the 30-year follow-up of the 1982 Pelotas (Brazil) birth cohort study

BACKGROUND

Cardiovascular diseases are the main cause of death globally. Interleukin-6 (IL-6) is a biomarker of cardiovascular risk.

AIM

To investigate factors associated with IL-6 concentration in serum, from early life up to 30 years of age.

SUBJECTS AND METHODS

In the 2012-2013 follow-up, IL-6 was measured in 2809 participants of the 1982 Pelotas Birth Cohort (1369 males). Multivariable linear regressions, stratified by sex, were performed to evaluate the associations of African ancestry, family income and maternal education at birth, monthly income and education at 30 years, smoking status, harmful alcohol intake, physical activity, and body composition with IL-6, considering a conceptual hierarchical framework.

RESULTS

Males with low educational levels and current smokers had the highest mean IL-6. Among females, African ancestry and low monthly income were associated with the highest mean values for the outcome. Physical activity had an inverse association with IL-6 concentration among females. A direct relationship was observed between the measures of adiposity on IL-6, in both sexes.

CONCLUSION

Body composition was the main predictor for the outcome evaluated in males and females. Thus, the avoidance of overweight remains an important strategy for the prevention and control of cardiovascular risk and biomarkers associated with these diseases.

Measurement of Interleukin-6 Levels in COVID: Illuminative or Illogical?

How to cite this article: Hegde A. Measurement of Interleukin-6 Levels in COVID: Illuminative or Illogical? Indian J Crit Care Med 2022;26(1):9–10.

Frequent Interpersonal Stress and Inflammatory Reactivity Predict Depressive-Symptom Increases: Two Tests of the Social-Signal-Transduction Theory of Depression

The social-signal-transduction theory of depression asserts that people who experience ongoing interpersonal stressors and mount a greater inflammatory response to social stress are at higher risk for depression. The current study tested this theory in two adult samples. In Study 1, physically healthy adults (N = 76) who reported more frequent interpersonal tension had heightened depressive symptoms at Visit 2, but only if they had greater inflammatory reactivity to a marital conflict at Visit 1. Similarly, in Study 2, depressive symptoms increased among lonelier and less socially supported breast-cancer survivors (N = 79). This effect was most pronounced among participants with higher inflammatory reactivity to a social-evaluative stressor at Visit 1. In both studies, noninterpersonal stress did not interact with inflammatory reactivity to predict later depressive symptoms.

Soluble Urokinase Plasminogen Activator Receptor (suPAR) as a Biomarker of Systemic Chronic Inflammation

Systemic chronic inflammation (SCI) is persistent, health-damaging, low-grade inflammation that plays a major role in immunosenescence and in development and progression of many diseases. But currently, there are no recognized standard biomarkers to assess SCI levels alone, and SCI is typically measured by combining biomarkers of acute inflammation and infection, e.g., CRP, IL-6, and TNFα. In this review, we highlight 10 properties and characteristics that are shared by the blood protein soluble urokinase plasminogen activator receptor (suPAR) and SCI, supporting the argument that suPAR is a biomarker of SCI: (1) Expression and release of suPAR is upregulated by immune activation; (2) uPAR and suPAR exert pro-inflammatory functions; (3) suPAR is associated with the amount of circulating immune cells; (4) Blood suPAR levels correlate with the levels of established inflammatory biomarkers; (5) suPAR is minimally affected by acute changes and short-term influences, in contrast to many currently used markers of systemic inflammation; (6) Like SCI, suPAR is non-specifically associated with multiple diseases; (7) suPAR and SCI both predict morbidity and mortality; (8) suPAR and SCI share the same risk factors; (9) suPAR is associated with risk factors and outcomes of inflammation above and beyond other inflammatory biomarkers; (10) The suPAR level can be reduced by anti-inflammatory interventions and treatment of disease. Assessing SCI has the potential to inform risk for morbidity and mortality. Blood suPAR is a newer biomarker which may, in fact, be a biomarker of SCI since it is stably associated with inflammation and immune activation; shares the same risk factors as many age-related diseases; is both elevated by and predicts age-related diseases. There is strong evidence that suPAR is a prognostic marker of adverse events, morbidity, and mortality. It is associated with immune activity and prognosis across diverse conditions, including kidney disease, cardiovascular disease, cancer, diabetes, and inflammatory disorders. Thus, we think it likely represents a common underlying disease-process shared by many diseases; that is, SCI. We review the supporting literature and propose a research agenda that can help test the hypothesis that suPAR indexes SCI, with the potential of becoming the new gold standard for measuring SCI.

Inconsistent effects of sleep deprivation on memory function

In this review article, we aimed to discuss the role of sleep deprivation (SD) in learning and memory processing in basic and clinical studies. There are numerous studies investigating the effect of SD on memory, while most of these studies have shown the impairment effect of SD. However, some of these studies have reported conflicting results, indicating that SD does not impair memory performance or even improves it. So far, no study has discussed or compared the conflicting results of SD on learning and memory. Thus, this important issue in the neuroscience of sleep remains unknown. The main goal of this review article is to compare the similar mechanisms between the impairment and the improvement effects of SD on learning and memory, probably leading to a scientific solution that justifies these conflicting results. We focused on the inconsistent effects of SD on some mechanisms involved in learning and memory, and tried to discuss the inconsistent effects of SD on learning and memory.