Eppur Si Muove: ferritin is essential in modulating inflammation

Salivary biomarkers as pioneering indicators for diagnosis and severity stratification of pediatric long COVID

Introduction

Long COVID, or post-acute sequelae of SARS-CoV-2 infection (PASC), manifests as persistent and often debilitating symptoms enduring well beyond the initial COVID-19 infection. This disease is especially worrying in children since it can seriously alter their development. Presently, a specific diagnostic test or definitive biomarker set for confirming long COVID is lacking, relying instead on the protracted presence of symptoms post-acute infection.

Methods

We measured the levels of 13 biomarkers in 105 saliva samples (49 from children with long COVID and 56 controls), and the Pearson correlation coefficient was used to analyse the correlations between the levels of the different salivary biomarkers. Multivariate logistic regression analyses were performed to determine which of the 13 analysed salivary biomarkers were useful to discriminate between children with long COVID and controls, as well as between children with mild and severe long COVID symptoms.

Results

Pediatric long COVID exhibited increased oxidant biomarkers and decreased antioxidant, immune response, and stress-related biomarkers. Correlation analyses unveiled distinct patterns between biomarkers in long COVID and controls. Notably, a multivariate logistic regression pinpointed TOS, ADA2, total proteins, and AOPP as pivotal variables, culminating in a remarkably accurate predictive model distinguishing long COVID from controls. Furthermore, total proteins and ADA1 were instrumental in discerning between mild and severe long COVID symptoms.

Discussion

This research sheds light on the potential clinical utility of salivary biomarkers in diagnosing and categorizing the severity of pediatric long COVID. It also lays the groundwork for future investigations aimed at unravelling the prognostic value of these biomarkers in predicting the trajectory of long COVID in affected individuals.

Ferritin: Significance in viral infections

As an indispensable trace element, iron is essential for many biological processes. Increasing evidence has shown that virus infection can perturb iron metabolism and play a role in the occurrence and development of viral infection-related diseases. Ferritin plays a crucial role in maintaining the body's iron homoeostasis. It is an important protein to stabilise the iron balance in cells. Ferritin is a 24-mer hollow iron storage protein composed of two subunits: ferritin heavy chain and ferritin light chain. It was reported that ferritin is not only an intra-cellular iron storage protein, but also a pathogenic mediator that enhances the inflammatory process and stimulates the further inflammatory pathway, which is a key member of the vicious pathogenic cycle to perpetuate. Ferritin exerts immuno-suppressive and pro-inflammatory functions during viral infection. In this review, we describe in detail the basic information of ferritin in the first section, including its structural features, the regulation of ferritin. In the second part, we focus on the role of ferritin in viral infection-related diseases and the molecular mechanisms by which viral infection regulates ferritin. The last section briefly outlines the potential of ferritin in antiviral therapy. Given the importance of iron and viral infection, understanding the role of ferritin during viral infection helps us understand the relationship between iron metabolic dysfunction and viral infection, which provides a new direction for the development of antiviral therapeutic drugs.

Serum ferritin and neutrophil-to-lymphocyte ratio predict all-cause mortality in patients receiving maintenance hemodialysis: a prospective study

Introduction: Maintenance hemodialysis is an effective treatment for end-stage renal disease patients. A critical factor contributing to the deterioration and death of maintenance hemodialysis patients is inflammation. Therefore, we focused on two inflammatory markers, serum ferritin and neutrophil-to-lymphocyte ratio, to speculate whether they could predict the prognosis of maintenance hemodialysis patients. Patients and methods: We followed 168 patients with maintenance hemodialysis from July 2019 to July 2022 with the endpoint of all-cause death or follow-up completion. Receiver operating characteristic curves were plotted to assess the values of serum ferritin, neutrophil-to-lymphocyte ratio and serum ferritin combined with neutrophil-to-lymphocyte ratio to predict the outcomes of maintenance hemodialysis patients. Kaplan-Meier survival curves were constructed to compare survival rates over time. Results: Receiver operating characteristic curves demonstrated that the best cut-off value of serum ferritin for predicting the prognosis of maintenance hemodialysis patients was 346.05 μg/L, and that of neutrophil-to-lymphocyte ratio was 3.225. Furthermore, a combination of both had a more excellent predicting value than either index (p < 0.05). Kaplan-Meier survival curve analyses revealed that low serum ferritin levels and low neutrophil-to-lymphocyte ratio had a higher probability of survival than high ferritin levels and high neutrophil-to-lymphocyte ratio, separately. Conclusion: Elevated serum ferritin and neutrophil-to-lymphocyte ratio are closely related to all-cause mortality among maintenance hemodialysis patients, for which they may be predictors of all-cause mortality. Additionally, the combination of the two has a much higher predictor value for the prognosis of maintenance hemodialysis patients.

Characterisation of Ferritin-Lymphocyte Ratio in COVID-19

Introduction: The ferritin-lymphocyte ratio (FLR) is a novel inflammatory biomarker for the assessment of acute COVID-19 patients. However, the prognostic value of FLR for predicting adverse clinical outcomes in COVID-19 remains unclear, which hinders its clinical translation. Methods: We characterised the prognostic value of FLR in COVID-19 patients, as compared to established inflammatory markers. Results: In 217 study patients (69 years [IQR: 55-82]; 60% males), FLR was weakly correlated with CRP (R = 0.108, p = 0.115) and white cell count (R = -0.144; p = 0.034). On ROC analysis, an FLR cut-off of 286 achieved a sensitivity of 86% and a specificity of 30% for predicting inpatient mortality (AUC 0.60, 95% CI: 0.53-0.67). The negative predictive values of FLR for ruling out mortality, non-invasive ventilation requirement and critical illness (intubation and/or ICU admission) were 86%, 85% and 93%, respectively. FLR performed similarly to CRP (AUC 0.60 vs. 0.64; p = 0.375) for predicting mortality, but worse than CRP for predicting non-fatal outcomes (all p < 0.05). On Kaplan-Meier analysis, COVID-19 patients with FLR values > 286 had worse inpatient survival than patients with FLR ≤ 286, p = 0.041. Conclusions: FLR has prognostic value in COVID-19 patients, and appears unrelated to other inflammatory markers such as CRP and WCC. FLR exhibits high sensitivity and negative predictive values for adverse clinical outcomes in COVID-19, and may be a good "rule-out" test. Further work is needed to improve the sensitivity of FLR and validate its role in prospective studies for guiding clinical management.

Association between Serum Ferritin and Prognosis in Patients with Ischemic Heart Disease in Intensive Care Units

PURPOSE

Recent years have seen a clear link established between elevated ferritin levels and COVID-19 prognosis. However, the impact of heightened ferritin levels on the prognosis of individuals with severe ischemic heart disease remains uncertain.

METHODS

We utilized the MIMIC IV database to identify a cohort of ischemic heart disease patients who underwent serum ferritin testing. We conducted regression analyses, employed the overlap propensity score weighting model, and utilized the restricted cubic splines model to comprehensively investigate the associations between serum ferritin levels and clinical outcomes.

RESULTS

Our cohort included 1173 patients with diagnosed ischemic heart disease, categorized into high and low serum ferritin groups. After meticulous adjustment for confounding factors in a fully adjusted model, the hazard ratios (HRs) for 90-day and 1-year mortality were 1.63 (95% CI: 1.27-2.09) and 1.49 (95% CI: 1.19-1.86), respectively, in the high-ferritin group compared to the low-ferritin group. Subsequent analyses with propensity score weighting confirmed these results. Remarkably, restricted cubic spline analysis revealed an almost linear relationship between log-transformed serum ferritin levels and the risk of both 90-day and 1-year all-cause mortality. Moreover, incorporating ferritin into conventional severity of illness scores significantly improved the area under the curve for both 90-day and 1-year mortality.

CONCLUSIONS

This study provides compelling evidence regarding the prognostic significance of serum ferritin in predicting 90-day and one-year mortality rates among patients diagnosed with ischemic heart disease.

The associations between dietary fibers intake and systemic immune and inflammatory biomarkers, a multi-cycle study of NHANES 2015-2020

Background

In recent years, there has been considerable growth in abnormal inflammatory reactions and immune system dysfunction, which are implicated in chronic inflammatory illnesses and a variety of other conditions. Dietary fibers have emerged as potential regulators of the human immune and inflammatory response. Therefore, this study aims to investigate the associations between dietary fibers intake and systemic immune and inflammatory biomarkers.

Methods

This cross-sectional study used data from the National Health and Nutrition Examination Survey (2015-2020). Dietary fibers intake was defined as the mean of two 24-h dietary recall interviews. The systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), neutrophil-to-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), red blood cell distribution width-to-albumin ratio (RA), ferritin, high-sensitivity C-reactive protein (hs-CRP), and white blood cell (WBC) count were measured to evaluate systemic immune and inflammatory states of the body. The statistical software packages R and EmpowerStats were used to examine the associations between dietary fibers intake and systemic immune and inflammatory biomarkers.

Results

Overall, 14,392 participants were included in this study. After adjusting for age, gender, race, family monthly poverty level index, alcohol consumption, smoking status, vigorous recreational activity, body mass index, hyperlipidemia, hypertension, diabetes, and dietary inflammatory index, dietary fibers intake was inversely associated with SII (β = -2.19885, 95% CI: -3.21476 to -1.18294, p = 0.000248), SIRI (β = -0.00642, 95% CI: -0.01021 to -0.00263, p = 0.001738), NLR (β = -0.00803, 95% CI: -0.01179 to -0.00427, p = 0.000284), RA (β = -0.00266, 95% CI: -0.00401 to -0.00131, p = 0.000644), ferritin (β = -0.73086, 95% CI: -1.31385 to -0.14787, p = 0.020716), hs-CRP (β = -0.04629, 95% CI: -0.0743 to -0.01829, p = 0.002119), WBC (β = -0.01624, 95% CI: -0.02685 to -0.00563, p = 0.004066), neutrophils (β = -0.01346, 95% CI: -0.01929 to -0.00764, p = 0.000064). An inverse association between dietary fibers and PLR was observed in the middle (β = -3.11979, 95% CI: -5.74119 to -0.4984, p = 0.028014) and the highest tertile (β = -4.48801, 95% CI: -7.92369 to -1.05234, p = 0.016881) and the trend test (βtrend = -2.2626, 95% CI: -3.9648 to -0.5604, Ptrend = 0.0150). The observed associations between dietary fibers intake and SII, SIRI, NLR, RA, ferritin, hs-CRP, WBC, and neutrophils remained robust and consistent in the sensitivity analysis. No significant interaction by race was found.

Conclusion

Dietary fibers intake is associated with the improvement of the parameters of the immune response and inflammatory biomarkers, supporting recommendations to increase dietary fibers intake for enhanced immune health.

Serum Ferritin in Obese Dogs: Changes and Comparison with Other Analytes

Canine obesity is the most common nutritional disorder and is associated with decreased quality of life and longevity as well as comorbidities including cardiorespiratory, endocrine, oncologic, or orthopaedic disorders. Ferritin is a major acute-phase protein in dogs, increasing during inflammation; however, it could also be affected by other conditions, including trauma, iron metabolism dysregulations, neoplasia, or hypoxia. Higher ferritin levels have been reported in obese humans, but ferritin has not been explored in canine obesity. To evaluate the possible changes in serum ferritin in canine obesity, ferritin levels from lean/normal weight (CG, n = 55) and overweight/obese dogs (OG, n = 37) were measured, together with complete hemogram and biochemical analyses. Statistically significant higher ferritin levels (1.2-fold) were found in OG (median, (interquartile range), 204 (166-227.5) µg/L) in comparison to CG animals (172 (137-210) µg/L)), with median levels of ferritin in OG dogs above the reference range for healthy animals in our laboratory (60-190 µg/L). In addition, statistically significant higher mean corpuscular volume (MCV), mean cell haemoglobin concentration (MCHC), total proteins, globulins, haptoglobin, total ferric fixation capacity (TIBC), alkaline phosphatase (ALP), butyrylcholinesterase (BChE), triglycerides, and calcium were observed in OG in comparison to CG. The higher levels in ferritin, together with higher TBIC, haematocrit, and MCV, could indicate tissue hypoxia in obese dogs.

Trace Elements and Ferritin in Pig Saliva: Variations during Fattening, Time of Sampling, Effect of Dirtiness and Stability under Different Storage Conditions

The objective of this study was to evaluate the possible changes of zinc (Zn), copper (Cu), iron (Fe) and ferritin during the entire productive cycle in fattening pigs and at different diurnal sampling times. Moreover, the possible effects of the presence of pen contaminants and storage stability at different temperature conditions were assessed. The analytes changed along the different phases of the fattening productive cycle, showing, in general, higher values at the initial phases. In addition, statistically significant variations were found in Zn and Cu measurements at different sampling times of the day. In the spectrophotometric assays, the values of all analytes significantly increased after adding high concentrations of feces or feed. However, when low concentrations of feces or feed were added, only Cu showed a significant increase. Overall, the salivary levels of Zn, Cu, Fe and ferritin in pigs can change during different fattening phases and the different hours of the day. These analytes were more stable at −80 °C and, if saliva is contaminated with feces or feed, it can lead to an increase in these analytes.

Inflammatory markers in rheumatic diseases

Immune-mediated rheumatic diseases (IMRDs) are a broad group of pathological conditions based on impaired immunological tolerance to one’s own tissues leading to inflammation and irreversible organ damage. Laboratory diagnosis of IMRDs includes a wide range of biomarkers (autoantibodies, acute phase proteins, cytokines, markers of endothelial damage, components of the complement system, immunoglobulins, cryoglobulins, lymphocyte subpopulations, indicators of bone metabolism, apoptosis markers, genetic markers, etc). One of the leading aspects of laboratory diagnosis of IMRDs is the study of the level of inflammation markers in the blood (erythrocyte sedimentation rate, C-reactive protein (CRP), serum amyloid protein (CAA), ferritin, procalcitonin, apolipoprotein AI, calprotectin, etc). The analysis of inflammation markers makes it possible to assess the disease activity, the nature of the progression and the prognosis of the outcomes of a chronic inflammatory process, as well as the effectiveness of the therapy. The review presents the latest data on the role of the most frequently studied inflammatory markers such as CRP, CAA and ferritin.

Automated assays for trace elements and ferritin measurement in saliva of pigs: Analytical validation and a pilot application to evaluate different iron status

The aim of this study was to validate automated methods to measure iron (Fe), zinc (Zn), copper (Cu) and ferritin in pig saliva samples. A complete analytical validation was performed of all assays. In addition, these methods were applied to saliva of Fe supplemented (n = 22) and non-supplemented (n = 20) piglets. All assays were able to measure these biomarkers in pig saliva with adequate precision, accuracy and high sensitivity and, in case of trace elements without needing a deproteinization pre-process. The group of piglets supplemented with Fe presented significantly higher levels of ferritin and Zn in saliva. In conclusion, the automated assays evaluated were able to measure Fe, Zn, Cu and ferritin in saliva of pigs, and in case of trace elements, they have the advantage of not needing a deproteinization pre-treatment and thus these analytes can be measured in a simple and fast manner.

Hemophagocytic lymphohistiocytosis diagnosed by bone marrow trephine biopsy in living post-COVID-19 patients: case report and mini-review

Hemophagocytic lymphohistiocytosis (HLH) constitutes a life-threatening inflammatory syndrome. Postmortem histological findings of bone marrow (BM) from COVID-19 patients showed histiocytosis and hemophagocytosis and supported the hypothesis that secondary HLH (sHLH) may be triggered by SARS-CoV-2 infection. However, there are a limited number of sHLH cases in which trephine has been performed in living post-COVID-19 patients. Here we present a recent case and a mini-review of sHLH diagnosed by trephine biopsy in living patients after COVID-19. An 81-year-old man with a past medical history of hypertension, diabetes, ischemic stroke, was referred to the hospital to evaluate leukocytosis, pyuria, and elevation of inflammatory markers four weeks after recovering from COVID-19. Computed tomography of the abdomen did not reveal focal signs of infection or hepatosplenomegaly. The patient received intravenous meropenem and two packed red blood cell units. Leukocytes and C-reactive protein were gradually decreased. A BM biopsy was performed and the patient was discharged on cefixime. BM smear revealed severe anemia, lymphopenia, and dysplastic morphologic findings of erythroblasts, neutrophils, and megakaryocytes. Trephine biopsy revealed hypercellular marrow dyserythropoiesis, plasmacytosis, lymphocytosis, histiocytosis, hemophagocytosis, and the absence of granulomas or carcinoma. Immunohistochemistry documented a mixed population of T lymphocytes (CD3+) and B lymphocytes (CD20+). Strong positivity for CD68 confirmed histiocytosis. CD138 κ, λ staining proved polyclonal plasmacytosis. Perl’s staining showed excess hemosiderin deposits. Based on our findings, we document sHLH in trephine BM biopsy of a living post-COVID-19 patient and persistent leukocytosis, underscoring the diagnostic value of trephine biopsy in preventing life-threatening conditions such as COVID-19.

Ferritin - from iron, through inflammation and autoimmunity, to COVID-19

While it took decades to arrive to a conclusion that ferritin is more than an indicator of iron storage level, it took a short period of time through the COVID-19 pandemic to wonder what the reason behind high levels of ferritin in patients with severe COVID-19 might be. Unsurprisingly, acute phase reactant was not a satisfactory explanation. Moreover, the behavior of ferritin in patients with severe COVID-19 and the subsequent high mortality rates in patients with high ferritin levels necessitated further investigations to understand the role of ferritin in the diseases. Ferritin was initially described to accompany various acute infections, both viral and bacterial, indicating an acute response to inflammation. However, with the introduction of the hyperferritinemic syndrome connecting four severe pathological conditions such as adult-onset Still's disease, macrophage activation syndrome, catastrophic antiphospholipid syndrome, and septic shock added another aspect of ferritin where it could have a pathogenetic role rather than an extremely elevated protein only. In fact, suggesting that COVID-19 is a new member in the spectrum of hyperferritinemic syndrome besides the four mentioned conditions could hopefully direct further search on the pathogenetic role of ferritin. Doubtlessly, improving our understanding of those aspects of ferritin would enormously contribute to better coping with severe diseases in terms of treatment and prevention of complications. The origin, history, importance, and the advances of searching the role of ferritin in various pathological and clinical processes are presented hereby in our article. In addition, the implications of ferritin in COVID-19 are addressed.

Salivary Ferritin Changes in Patients with COVID-19

High ferritin serum levels can be found in patients with macrophage activation syndrome, and increased serum ferritin due to cytokine storm have been reported in severe COVID-19 patients. Saliva is being increasingly used in COVID-19 tests as a diagnostic sample for virus detection and quantification. This study aimed to evaluate the possible changes in ferritin in saliva in COVID-19 patients. In addition, the effects of different inactivation SARS-CoV-2 treatments in ferritin measurements in saliva, the correlation between ferritin in saliva and serum, and the possible effects of correction of ferritin values by total protein were assessed. Ferritin was measured in saliva from healthy (n = 30) and COVID-19 (n = 65) patients with severe, (n = 18) or mild (n = 47) disease, depending on the need for nasal flow oxygen or assisted respiration. Ferritin was also measured in paired serum and saliva samples (n = 32) from healthy and COVID-19 patients. The evaluated inactivation protocols did not affect the assay's results except the addition of 0.5% SDS. Significantly higher ferritin was found in the saliva of COVID-19 patients (median; 25-75th percentile) (27.75; 9.77-52.2 µg/L), compared with healthy controls (4.21; 2.6-8.08 µg/L). Individuals with severe COVID-19 showed higher ferritin values in saliva (48.7; 18.7-53.9) than mild ones (15.5; 5.28-41.3 µg/L). Significant correlation (r = 0.425; p < 0.001) was found between serum and saliva in ferritin. Ferritin levels were higher in COVID-19 patients in serum and saliva, and the highest values were found in those patients presenting severe symptomatology. In conclusion, ferritin in saliva has the potential to be a biomarker to evaluate severity in patients with COVID-19.

Increased Lipid Peroxidation May Be Linked to Ferritin Levels Elevation in Adult-Onset Still's Disease

Lipid peroxidation (LPO) and hyper-ferritinemia are involved in inflammatory responses. Although hyper-ferritinemia is a characteristic of AOSD, its link to LPO remains unclear. We investigated the association between LPO and ferritin expression, and evaluated the relationship between LPO-related metabolites and inflammatory parameters. Mean fluorescence intensity (MFI) of LPO (C11-Biodipy^581/591)-expressing PBMCs/monocytes in AOSD patients and healthy control (HC) subjects was determined by flow-cytometry analysis. Expression of ferritin and cytokines on PBMCs/macrophages was examined by immunoblotting. Plasma levels of LPO-related metabolites and cytokines were determined by ELISA and the MULTIPLEX platform, respectively. LPO MFI on PBMCs/monocytes were significantly higher in patients (median 4456 and 9091, respectively) compared with HC (1900, p < 0.05, and 4551, p < 0.01, respectively). Patients had higher ferritin expression on PBMCs (mean fold, 1.02) than HC (0.55, p < 0.05). Their ferritin expression levels on PBMCs stimulated with LPO inducers erastin or RSL3 (2.47 or 1.61, respectively) were higher than HC (0.84, p < 0.05, or 0.74, p < 0.01). Ferritin expression on erastin-treated/IL-1β-treated macrophages from patients were higher than those from HC (p < 0.001). The elevated levels of LPO-related metabolites, including malondialdehyde and 4-hydroxyalkenals, were positively correlated with disease activity scores, suggesting LPO involvement in AOSD pathogenesis. Increased ferritin expression on PBMCs/macrophages stimulated with LPO inducers indicates a link between LPO and elevated ferritin.

Association of HScore Parameters with Severe COVID-19: A Systematic Review and Meta-Analysis

BACKGROUND

Several reports have associated the severe Coronavirus disease-2019 (sCOVID-19) with secondary-hemophagocytic lymphohistiocytosis (sHLH) and proposed utilizing the hemophagocytic syndrome diagnostic score (HScore) for sCOVID-19 patients. We conducted a systematic review and meta-analysis to find the possible association of HScore parameters with severity in COVID-19 patients.

METHODS

A systematic search was performed in Medline via PubMed, EMBASE, and Cochrane databases using all HScore and COVID-19 keywords. The studies were all from 2020, and the study language was limited to English. The records were screened based on inclusion/exclusion criteria. Random/fixed-effect models were employed for meta-analysis, based on the I2 index of parameters. The pooled mean differences were estimated for continuous parameters. The pooled odds-ratio was estimated for fever. The level of significance was set at 0.05.

RESULTS

Eighteen studies (comprising 2459 patients) out of 26151 screened studies were included in this meta-analysis. The results showed that the level of leukocyte, neutrophil, aspartate transaminase (AST), ferritin, and fibrinogen were significantly higher in sCOVID-19 patients than in non-severe ones. Significant lower levels of lymphocyte, platelet, and hemoglobin were also found in sCOVID-19 patients than non-severe patients. Fever was nearly associated with two times increased odds of sCOVID-19 (P=0.051).

CONCLUSION

Lymphopenia, thrombocytopenia, hypohemoglobinemia, hyperferritinemia, high levels of AST, and fever are common features of both sCOVID-19 and HLH. However, the leukocytosis, neutrophilia, and hyperfibrinogenemia found in sCOVID-19 are in contrast with HScore. Conclusively, HScore parameters could be risk factors for sCOVID-19. However, some parameters' roles are contradictory, suggesting the need for further investigation and a new way of HScore interpretation in sCOVID-19 patients.A preprint of this study was published at https://www.researchsquare.com/article/rs-54490/v2.

Interleukin-18 Is a Potential Biomarker to Discriminate Active Adult-Onset Still's Disease From COVID-19

Background

Hyperinflammation with dysregulated production of galectins and cytokines may develop in COVID-19 or adult-onset Still's disease (AOSD). Given the similar clinical features in both diseases, it is necessary to identify biomarkers that can differentiate COVID-19 from AOSD. However, the related data remain scarce currently.

Methods

In this cross-sectional study, plasma levels of galectin-3, galectin-9, and soluble TIM-3 (sTIM-3) were determined by ELISA in 55 COVID-19 patients (31 non-severe and 24 severe), 23 active AOSD patients, and 31 healthy controls (HC). The seropositivity for SARS-CoV-2 was examined using an immunochromatographic assay, and cytokine profiles were determined with the MULTIPLEX platform.

Results

Significantly higher levels of galectin-3, galectin-9, IL-1β, IL-1Ra, IL-10, IFN-α2, IL-6, IL-18, and TNF-α were observed in severe COVID-19 and active AOSD patients compared with HC (all p<0.001). AOSD, but not COVID-19, showed significantly higher IFN-γ and IL-17A compared with HC (both p<0.01). Moreover, active AOSD patients had 68-fold higher IL-18 levels and 5-fold higher ferritin levels than severe COVID-19 patients (both p<0.001). IL-18 levels at the cut-off value 190.5pg/mL had the highest discriminative power for active AOSD and severe COVID-19, with AUC 0.948, sensitivity 91.3%, specificity 95.8%, and accuracy of 91.5% (p<0.005). Multivariate regression analysis revealed IL-18 as a significant predictor of active AOSD (p<0.05).

Conclusion

Active AOSD patients share features of hyperinflammation and cytokine storm with severe COVID-19 patients but possess a distinct cytokine profile, including elevated IL-18, IL-6, IFN-γ, and IL-17A. IL-18 is a potential discriminator between AOSD and COVID-19 and may significantly predict active AOSD.

An Update on the Pathogenic Role of Macrophages in Adult-Onset Still's Disease and Its Implication in Clinical Manifestations and Novel Therapeutics

Increasing evidence indicates a pivotal role of macrophages in innate immunity, which contributes to the pathogenesis of adult-onset Still's disease (AOSD). Despite the available reviews that summarized the pathogenic role of proinflammatory cytokines in AOSD, a systematic approach focusing on the crucial role of macrophages in this disease is still lacking. This review summarizes the updated functions of macrophages in AOSD and their implication in clinical manifestations and therapeutics. We searched the MEDLINE database using the PubMed interface and reviewed the English-language literature as of 31 March 2021, from 1971 to 2021. We focus on the existing evidence on the pathogenic role of macrophages in AOSD and its implication in clinical characteristics and novel therapeutics. AOSD is an autoinflammatory disease mainly driven by the innate immune response. Among the innate immune responses, macrophage activation is a hallmark of AOSD pathogenesis. The pattern recognition receptors (PRRs) on macrophages recognize pathogen-associated molecular patterns and damage-associated molecular patterns and subsequently cause overproduction of proinflammatory cytokines and recruit adaptive immunity. Some biomarkers, such as ferritin and gasdermin D, reflecting macrophage activation were elevated and correlated with AOSD activity. Given that macrophage activation with the overproduction of proinflammatory cytokines plays a pathogenic role in AOSD, these inflammatory mediators would be the therapeutic targets. Accordingly, the inhibitors to interleukin- (IL-) 1, IL-6, and IL-18 have been shown to be effective in AOSD treatment. Gaining insights into the pathogenic role of macrophages in AOSD can aid in identifying disease biomarkers and therapeutic agents for this disease.

Targeting Multiple Signal Transduction Pathways of SARS-CoV-2: Approaches to COVID-19 Therapeutic Candidates

Due to the complicated pathogenic pathways of coronavirus disease 2019 (COVID-19), related medicinal therapies have remained a clinical challenge. COVID-19 highlights the urgent need to develop mechanistic pathogenic pathways and effective agents for preventing/treating future epidemics. As a result, the destructive pathways of COVID-19 are in the line with clinical symptoms induced by severe acute coronary syndrome (SARS), including lung failure and pneumonia. Accordingly, revealing the exact signaling pathways, including inflammation, oxidative stress, apoptosis, and autophagy, as well as relative representative mediators such as tumor necrosis factor-α (TNF-α), nuclear factor erythroid 2-related factor 2 (Nrf2), Bax/caspases, and Beclin/LC3, respectively, will pave the road for combating COVID-19. Prevailing host factors and multiple steps of SARS-CoV-2 attachment/entry, replication, and assembly/release would be hopeful strategies against COVID-19. This is a comprehensive review of the destructive signaling pathways and host-pathogen interaction of SARS-CoV-2, as well as related therapeutic targets and treatment strategies, including potential natural products-based candidates.

Outcome Predictive Value of Serum Ferritin in ICU Patients with Long ICU Stay

Background and Objectives: The simplified interpretation of serum ferritin levels, according to which low ferritin levels indicate iron deficiency and high levels indicate hemochromatosis is obsolete, as in the presence of inflammation serum ferritin levels, no longer correlate with iron stores. However, further data are needed to interpret serum ferritin levels correctly in patients with ongoing inflammation. Our study aimed to assess serum iron and ferritin dynamics in patients with long ICU stay and the possible correlations with organ dysfunction progression and outcome. Materials and Methods: We conducted a prospective study in a university hospital intensive care unit (ICU) over six months. All patients with an ICU length-of-stay of more than seven days were enrolled. Collected data included: demographics, Sequential Organ Failure Assessment (SOFA) score, admission, weekly serum iron and ferritin levels, ICU length-of-stay and outcome. Interactions between organ dysfunction progression and serum iron and ferritin levels changes were investigated. Outcome predictive value of serum ferritin was assessed. Results: Seventy-two patients with a mean ICU length-of-stay of 15 (4.4) days were enrolled in the study. The average age of patients was 62 (16.8) years. There were no significant differences between survivors (39 patients, 54%) and nonsurvivors (33 patients, 46%) regarding demographics, serum iron and ferritin levels and SOFA score on ICU admission. Over time, serum iron levels remained normal or low, while serum ferritin levels statedly increased in all patients. Serum ferritin increase was higher in nonsurvivors than survivors. There was a significant positive correlation between SOFA score and serum ferritin (r = 0.7, 95%CI for r = 0.64 to 0.76, p < 0.01). The predictive outcome accuracy of serum ferritin was similar to the SOFA score. Conclusions: In patients with prolonged ICU stay, serum ferritin dynamics reflects organ dysfunction progression and parallels SOFA score in terms of outcome predictive accuracy.

Immunoglobulin deficiency as an indicator of disease severity in patients with COVID-19

Despite the pandemic status of COVID-19, there is limited information about host risk factors and treatment beyond supportive care. Immunoglobulin G (IgG) could be a potential treatment target. Our aim was to determine the incidence of IgG deficiency and associated risk factors in a cohort of 62 critically ill patients with COVID-19 admitted to two German ICUs (72.6% male, median age: 61 yr). Thirteen (21.0%) of the patients displayed IgG deficiency (IgG < 7 g/L) at baseline (predominant for the IgG1, IgG2, and IgG4 subclasses). Patients who were IgG-deficient had worse measures of clinical disease severity than those with normal IgG levels (shorter duration from disease onset to ICU admission, lower ratio of [Formula: see text] to [Formula: see text], higher Sequential Organ Failure Assessment score, and higher levels of ferritin, neutrophil-to-lymphocyte ratio, and serum creatinine). Patients who were IgG-deficient were also more likely to have sustained lower levels of lymphocyte counts and higher levels of ferritin throughout the hospital stay. Furthermore, patients who were IgG-deficient compared with those with normal IgG levels displayed higher rates of acute kidney injury (76.9% vs. 26.5%; P = 0.001) and death (46.2% vs. 14.3%; P = 0.012), longer ICU [28 (6-48) vs. 12 (3-18) days; P = 0.012] and hospital length of stay [30 (22-50) vs. 18 (9-24) days; P = 0.004]. Univariable logistic regression showed increasing odds of 90-day overall mortality associated with IgG-deficiency (odds ratio 5.14, 95% confidence interval 1.3-19.9; P = 0.018). IgG deficiency might be common in patients with COVID-19 who are critically ill, and warrants investigation as both a marker of disease severity as well as a potential therapeutic target.

Paper spray mass spectrometry utilizing Teslin® substrate for rapid detection of lipid metabolite changes during COVID-19 infection

The SARS-CoV-2 virus is known as the causal agent for the current COVID-19 global pandemic. The majority of COVID-19 patients develop acute respiratory distress syndrome (ARDS), while some experience a cytokine storm effect, which is considered as one of the leading causes of patient mortality. Lipids are known to be involved in the various stages of the lifecycle of a virus functioning as receptors or co-receptors that controls viral propagation inside the host cell. Therefore, lipid-related metabolomics aims to provide insight into the immune response of the novel coronavirus. Our study has focused on determination of the potential metabolomic biomarkers utilizing a Teslin® Substrate in paper spray mass spectrometry (PS-MS) for the development of a rapid detection test within 60 seconds of analysis time. In this study, results were correlated with PCR tests to reflect that the systemic responses of the cells were affected by the COVID-19 virus.

Pro-inflammatory properties of H-ferritin on human macrophages, ex vivo and in vitro observations

Ferritin is an iron-binding molecule, which comprises 24 subunits, heavy (FeH) and light (FeL) subunits, suggested to have a pathogenic role by the 'hyperferritinemic syndrome'. In this work, we tested (1) FeH and FeL in bone marrow (BM) and sera in patients with macrophage activation syndrome (MAS); (2) pro-inflammatory effects of ferritin, FeL, and FeH on macrophages; (3) ability of FeH-stimulated macrophages to stimulate the proliferation of peripheral blood mononuclear cells (PBMCs); (4) production of mature IL-1β and IL-12p70 in extracellular compartments of FeH-stimulated macrophages. Immunofluorescence analysis and liquid chromatography mass spectrometry (LC-MS/MS) based proteomics were performed to identify FeL and FeH in BM and sera, respectively, in the same patients. Macrophages were stimulated with ferritin, FeH, and FeL to assess pro-inflammatory effects by RT-PCR and western blot. The proliferation of co-cultured PBMCs with FeH-stimulated macrophages was tested. Immunofluorescence showed an increased FeH expression in BMs, whereas LC-MS/MS identified that FeL was mainly represented in sera. FeH induced a significant increase of gene expressions of IL-1β, IL-6, IL-12, and TNF-α, more marked with FeH, which also stimulated NLRP3. FeH-stimulated macrophages enhanced the proliferation of PBMCs. The ELISA assays showed that mature form of IL-1β and IL-12p70 were increased, in extracellular compartments of FeH-stimulated macrophages. Our results showed FeH in BM biopsies of MAS patients, whereas, LC-MS/MS identified FeL in the sera. FeH showed pro-inflammatory effects on macrophages, stimulated NLRP3, and increased PBMCs proliferation.

The Role of Cytokines including Interleukin-6 in COVID-19 induced Pneumonia and Macrophage Activation Syndrome-Like Disease

Severe COVID-19 associated pneumonia patients may exhibit features of systemic hyper-inflammation designated under the umbrella term of macrophage activation syndrome (MAS) or cytokine storm, also known as secondary haemophagocytic lymphohistocytosis (sHLH). This is distinct from HLH associated with immunodeficiency states termed primary HLH -with radically different therapy strategies in both situations. COVID-19 infection with MAS typically occurs in subjects with adult respiratory distress syndrome (ARDS) and historically, non-survival in ARDS was linked to sustained IL-6 and IL-1 elevation. We provide a model for the classification of MAS to stratify the MAS-like presentation in COVID-19 pneumonia and explore the complexities of discerning ARDS from MAS. We discuss the potential impact of timing of anti-cytokine therapy on viral clearance and the impact of such therapy on intra-pulmonary macrophage activation and emergent pulmonary vascular disease.

Hyperferritinaemia: An Iron Sword of Autoimmunity

BACKGROUND

Ferritin is a molecule that plays many roles being the storage for iron, signalling molecule, and modulator of the immune response.

METHODS

Different electronic databases were searched in a non-systematic way to find out the literature of interest.

RESULTS

The level of ferritin rises in many inflammatory conditions including autoimmune disorders. However, in four inflammatory diseases (i.e., adult-onset Still's diseases, macrophage activation syndrome, catastrophic antiphospholipid syndrome, and sepsis), high levels of ferritin are observed suggesting it as a remarkable biomarker and pathological involvement in these diseases. Acting as an acute phase reactant, ferritin is also involved in the cytokine-associated modulator of the immune response as well as a regulator of cytokine synthesis and release which are responsible for the inflammatory storm.

CONCLUSION

This review article presents updated information on the role of ferritin in inflammatory and autoimmune diseases with an emphasis on hyperferritinaemic syndrome.

Biomarkers of Physiological Responses to Periods of Intensified, Non-Resistance-Based Exercise Training in Well-Trained Male Athletes: A Systematic Review and Meta-Analysis

BACKGROUND

Intensified training is important for inducing adaptations to improve athletic performance, but detrimental performance effects can occur if prescribed inappropriately. Monitoring biomarker responses to training may inform changes in training load to optimize performance.

OBJECTIVE

This systematic review and meta-analysis aimed to identify biomarkers associated with altered exercise performance following intensified training.

METHODS

Embase, MEDLINE, CINAHL, Scopus and SPORTDiscus were searched up until September 2017. Included articles were peer reviewed and reported on biomarkers collected at rest in well-trained male athletes before and after periods of intensified training.

RESULTS

The full text of 161 articles was reviewed, with 59 included (708 participants) and 42 (550 participants) meta-analysed. In total, 118 biomarkers were evaluated, with most being cellular communication and immunity markers (n = 54). Studies most frequently measured cortisol (n = 34), creatine kinase (n = 25) and testosterone (n = 20). Many studies reported decreased immune cell counts following intensified training, irrespective of performance. Moreover, reduced performance was associated with a decrease in neutrophils (d = - 0.57; 95% confidence interval (CI) - 1.07 to - 0.07) and glutamine (d = - 0.37; 95% CI - 0.43 to - 0.31) and an increase in urea concentration (d = 0.80; 95% CI 0.30 to 1.30). In contrast, increased performance was associated with an increased testosterone:cortisol ratio (d = 0.89; 95% CI 0.54 to 1.24). All remaining biomarkers showed no consistent patterns of change with performance.

CONCLUSIONS

Many biomarkers were altered with intensified training but not in a manner related to changes in exercise performance. Neutrophils, glutamine, urea and the testosterone:cortisol ratio exhibited some evidence of directional changes that corresponded with performance changes therefore indicating potential to track performance. Additional investigations of the potential for these markers to track altered performance are warranted.

The Association Between Osteocalcin and Chronic Inflammation in Patients with Type 2 Diabetes Mellitus

Osteocalcin acts as an endocrine hormone to regulate energy homeostasis. Although several in vivo and in vitro studies suggest that osteocalcin is involved in chronic inflammation, the association between osteocalcin and chronic inflammation in humans is unknown. In this cross-sectional study, 246 patients with type 2 diabetes mellitus (T2DM) were recruited to investigate the association of bone turnover markers with chronic inflammation parameters such as high-sensitive C-reactive protein (hsCRP), ferritin, and leukocyte subtype counts. Bone-specific alkaline phosphatase (BAP), total osteocalcin (OC), undercarboxylated OC (ucOC), and urinary N-terminal cross-linked telopeptide of type-I collagen (uNTX) were measured. Multiple regression analysis adjusted for age, duration of diabetes, body mass index, estimated glomerular filtration rate, and hemoglobin A1c showed that serum OC levels were significantly and negatively associated with hsCRP, ferritin, basophil count, and monocyte count (β = - 0.18, p = 0.013; β = - 0.22, p = 0.031; β = - 0.14, p = 0.038; and β = - 0.17, p = 0.012, respectively). Moreover, serum ucOC levels were significantly and negatively associated with hsCRP, ferritin, total leukocyte count, neutrophil count, and monocyte count (β = - 0.24, p = 0.007; β =- 0.37, p = 0.003; β = - 0.21, p = 0.007; β = - 0.24, p = 0.002; and β = - 0.20, p = 0.011, respectively). The ratio of ucOC to OC was significantly and negatively associated with ferritin (β = - 0.31, p = 0.014). However, neither BAP nor uNTX was associated with any chronic inflammation parameters. This is the first study to show that serum OC and ucOC levels were negatively associated with chronic inflammation parameters such as hsCRP, ferritin, and leukocyte subtypes in patients with T2DM. Therefore, OC could be a therapeutic target for protecting against chronic inflammation.