Outcome prediction by serum calprotectin in patients with COVID-19 in the emergency department

Targeting furin, a cellular proprotein convertase, for COVID-19 prevention and therapeutics

SARS-CoV-2 has triggered an international outbreak of the highly contagious acute respiratory disease known as COVID-19. Identifying key targets in the virus infection lifecycle is crucial for developing effective prevention and therapeutic strategies against it. Furin is a serine endoprotease that belongs to the family of proprotein convertases and plays a critical role in the entry of host cells by SARS-CoV-2. Furin can cleave a specific S1/S2 site, PRRAR, on the spike protein of SARS-CoV-2, which promotes viral transmission by facilitating membrane fusion. Hence, targeting furin could hold clinical implications for the prevention and treatment of COVID-19. This review offers an overview of furin's structure, substrates, function, and inhibitors, with a focus on its potential role in SARS-CoV-2 infection.

Blood calprotectin as a biomarker for infection and sepsis - the prospective CASCADE trial

BACKGROUND

Early in the host-response to infection, neutrophils release calprotectin, triggering several immune signalling cascades. In acute infection management, identifying infected patients and stratifying these by risk of deterioration into sepsis, are crucial tasks. Recruiting a heterogenous population of patients with suspected infections from the emergency department, early in the care-path, the CASCADE trial aimed to evaluate the accuracy of blood calprotectin for detecting bacterial infections, estimating disease severity, and predicting clinical deterioration.

METHODS

In a prospective, observational trial from February 2021 to August 2022, 395 patients (n = 194 clinically suspected infection; n = 201 controls) were enrolled. Blood samples were collected at enrolment. The accuracy of calprotectin to identify bacterial infections, and to predict and identify sepsis and mortality was analysed. These endpoints were determined by a panel of experts.

RESULTS

The Area Under the Receiver Operating Characteristic (AUROC) of calprotectin for detecting bacterial infections was 0.90. For sepsis within 72 h, calprotectin's AUROC was 0.83. For 30-day mortality it was 0.78. In patients with diabetes, calprotectin had an AUROC of 0.94 for identifying bacterial infection.

CONCLUSIONS

Calprotectin showed notable accuracy for all endpoints. Using calprotectin in the emergency department could improve diagnosis and management of severe infections, in combination with current biomarkers.

CLINICAL TRIAL REGISTRATION NUMBER

DRKS00020521.

Validation of Serum Calprotectin Relative to Other Biomarkers of Infection in Febrile Infants Presenting to the Emergency Department

Antimicrobial stewardship involves a delicate balance between the risk of undertreating individuals and the potential societal burden of overprescribing antimicrobials. This balance is especially crucial in neonatal care. In this observational study, the usefulness of biomarkers of infectious diseases (calprotectin, procalcitonin (PCT), C-reactive protein (CRP), and white blood cells (WBCs) were evaluated in 141 febrile infants aged 28-90 days presenting to an emergency department. Since our focus was on the usefulness of serum calprotectin, this biomarker was not part of clinical decision-making. A significant difference was observed in the levels of all biomarkers, related to final discharge diagnosis and disposition status. The difference in levels related to antibiotic prescription was significant for all biomarkers but WBCs. The performance of calprotectin in the detection of bacterial infections (AUC (95% CI): 0.804 (0.691, 0.916)) was comparable to the performance of both PCT (0.901 (0.823, 0.980)) and CRP (0.859 (0.764, 0.953)) and superior to the WBC count (0.684 (0.544, 0.823)). Procalcitonin and CRP demonstrated a statistically significantly higher specificity relative to calprotectin. In this cohort, antibiotic use did not always correlate to a definite diagnosis of confirmed bacterial infection. The sample size was limited due to associated challenges with recruiting febrile infants. Hence, there is a need for adequate diagnostic tools to help discriminate between various kinds of infections. This study suggests serum calprotectin, procalcitonin, and CRP may serve as valuable biomarkers to differentiate between types of infection, in addition to clinical input and decision-making.

Calprotectin serum levels on admission and during follow-up predict severity and outcome of patients with COVID-19: A prospective study

BACKGROUND & AIMS

Calprotectin reflects neutrophil activation and is increased in various inflammatory conditions including severe COVID-19. However, serial serum calprotectin measurements in COVID-19 patients are limited. We assessed prospectively, calprotectin levels as biomarker of severity/outcome of the disease and a COVID-19 monitoring parameter in a large cohort of consecutive COVID-19 patients.

METHODS

Calprotectin serum levels were measured in 736 patients (58.2 % males; median age 63-years; moderate disease, n = 292; severe, n = 444, intubated and/or died, n = 50). Patients were treated with combined immunotherapies according to our published local algorithm. The endpoint was the composite event of intubation due to severe respiratory failure (SRF)/COVID-19-related mortality.

RESULTS

Median (interquartile range) calprotectin levels were significantly higher in patients with severe disease [7(8.2) vs. 6.1(8.1)μg/mL, p = 0.015]. Calprotectin on admission was the only independent risk factor for intubation/death (HR=1.473, 95 %CI=1.003-2.165, p = 0.048) even after adjustment for age, sex, body mass index, comorbidities, neutrophils, lymphocytes, neutrophil to lymphocytes ratio, ferritin, and CRP. The area under the curve (AUC, 95 %CI) of calprotectin for prediction of intubation/death was 0.619 (0.531-0.708), with an optimal cut-off at 13 μg/mL (sensitivity: 44 %, specificity: 79 %, positive and negative predictive values: 13 % and 95 %, respectively). For intubated/died patients, paired comparisons from baseline to middle of hospitalization and subsequently to intubation/death showed significant increase of calprotectin (p = 0.009 and p < 0.001, respectively). Calprotectin alteration had the higher predictive ability for intubation/death [AUC (95 %CI):0.803 (0.664-0.943), p < 0.001].

CONCLUSIONS

Calprotectin levels on admission and their subsequent dynamic alterations could serve as indicator of COVID-19 severity and predict the occurrence of SRF and mortality.

Elevated level of circulating calprotectin correlates with severity and high mortality in patients with COVID-19

BACKGROUND

Patients with coronavirus disease-2019 (COVID-19) are characterized by hyperinflammation. Calprotectin (S100A8/S100A9) is a calcium- and zinc-binding protein mainly secreted by neutrophilic granulocytes or macrophages and has been suggested to be correlated with the severity and prognosis of COVID-19.

AIM

To thoroughly evaluate the diagnostic and prognostic utility of calprotectin in patients with COVID-19 by analyzing relevant studies.

METHODS

PubMed, Web of Science, and Cochrane Library were comprehensively searched from inception to August 1, 2023 to retrieve studies about the application of calprotectin in COVID-19. Useful data such as the level of calprotectin in different groups and the diagnostic efficacy of this biomarker for severe COVID-19 were extracted and aggregated by using Stata 16.0 software.

RESULTS

Fifteen studies were brought into this meta-analysis. First, the pooled standardized mean differences (SMDs) were used to estimate the differences in the levels of circulating calprotectin between patients with severe and non-severe COVID-19. The results showed an overall estimate of 1.84 (95% confidence interval [CI]: 1.09-2.60). Diagnostic information was extracted from 11 studies, and the pooled sensitivity and specificity of calprotectin for diagnosing severe COVID-19 were 0.75 (95% CI: 0.64-0.84) and 0.88 (95% CI: 0.79-0.94), respectively. The AUC was 0.89 and the pooled DOR was 18.44 (95% CI: 9.07-37.51). Furthermore, there was a strong correlation between elevated levels of circulating calprotectin and a higher risk of mortality outcomes in COVID-19 patients (odds ratio: 8.60, 95% CI: 2.17-34.12; p < 0.1).

CONCLUSION

This meta-analysis showed that calprotectin was elevated in patients with severe COVID-19, and this atypical inflammatory cytokine might serve as a useful biomarker to distinguish the severity of COVID-19 and predict the prognosis.

Successful management of concurrent COVID-19 and Pneumocystis Jirovecii Pneumonia in kidney transplant recipients: a case series

BACKGROUND

Pneumocystis pneumonia (PCP) is a life-threatening pulmonary fungal infection that predominantly affects immunocompromised individuals, including kidney transplant recipients. Recent years have witnessed a rising incidence of PCP in this vulnerable population, leading to graft loss and increased mortality. Immunosuppression, which is essential in transplant recipients, heightens susceptibility to viral and opportunistic infections, magnifying the clinical challenge. Concurrently, the global impact of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been profound. Kidney transplant recipients have faced severe outcomes when infected with SARS-CoV-2, often requiring intensive care. Co-infection with COVID-19 and PCP in this context represents a complex clinical scenario that requires precise management strategies, involving a delicate balance between immunosuppression and immune activation. Although there have been case reports on management of COVID-19 and PCP in kidney transplant recipients, guidance on how to tackle these infections when they occur concurrently remains limited.

CASE PRESENTATIONS

We have encountered four kidney transplant recipients with concurrent COVID-19 and PCP infection. These patients received comprehensive treatment that included adjustment of their maintenance immunosuppressive regimen, anti-pneumocystis therapy, treatment for COVID-19 and other infections, and symptomatic and supportive care. After this multifaceted treatment strategy, all of these patients improved significantly and had favorable outcomes.

CONCLUSIONS

We have successfully managed four kidney transplant recipients co-infected with COVID-19 and PCP. While PCP is a known complication of immunosuppressive therapy, its incidence in patients with COVID-19 highlights the complexity of dual infections. Our findings suggest that tailored immunosuppressive regimens, coupled with antiviral and antimicrobial therapies, can lead to clinical improvement in such cases. Further research is needed to refine risk assessment and therapeutic strategies, which will ultimately enhance the care of this vulnerable population.

Elevated Level of Circulating but Not Urine S100A8/A9 Identifies Poor COVID-19 Outcomes

The alarmin calprotectin (S100A8/A9) is thought to drive a cytokine storm, a hallmark of severe COVID-19. Recent studies report circulating S100A8/A9 levels can distinguish COVID-19 severity but have only been conducted in non-U.S. cohorts and mainly focus on serum S100A8/A9 levels. Thus, we quantified S100A8/A9 in serum and urine samples from a hospital cohort in St. Louis, Missouri, to expand the understanding of S100A8/A9 as a prognostic biomarker for COVID-19. Elevated S100A8/A9 serum levels were observed in ICU patients (n = 49, p = 0.0370) and patients with fatal cases of COVID-19 (n = 76, p = 0.0018). We observed no correlation in the S100A8/A9 levels in matched serum and urine samples. Our results support the association of serum S100A8/A9 levels with COVID-19 severity and suggest that further investigation of urine S100A8/A9 as a COVID-19 biomarker is not warranted.

Analysis of Calprotectin as an Early Marker of Infections Is Economically Advantageous in Intensive Care-Treated Patients

Calprotectin is released from neutrophil granulocytes upon activation. Several studies have indicated that plasma calprotectin is an early determinant of bacterial infections, which may serve as a diagnostic tool facilitating decision making on antibiotic treatment. The study objective was to explore the health and economic implications of calprotectin as a predictive tool to initiate antimicrobial therapy in a cohort of critically ill patients. Thus, data obtained from a previously published study on calprotectin as a hypothetical early biomarker of bacterial infections in critically ill patients were evaluated regarding the potential cost-effective impact of early analysis of calprotectin on an earlier start of antibiotic treatment. Under the assumption that calprotectin is used predictively and comparators (white blood cells, procalcitonin, and C-reactive protein) are used diagnostically, a cost-effective impact of EUR 11,000-12,000 per patient would be obtained. If calprotectin would be used predictively and comparators would be used predictively for 50% of patients, it is hypothesized that cost-effectiveness would be between EUR 6000 and 7000 per patient, based on reduced stay in the ICU and general ward, respectively. Furthermore, predictive use of calprotectin seems to reduce both mortality and the length of hospital stay. This health economic analysis on the predictive use of plasma calprotectin, which facilitates clinical decision making in cases of suspected sepsis, indicates that such determination has a cost-saving and life-saving impact on the healthcare system.

Chicken antibodies are highly suitable for particle enhanced turbidimetric assays

Antibody-based assays are commonly used in clinical laboratories for analyzing plasma, serum and other samples for particular protein markers. Although such assays have been traditionally based on antibodies raised in mammals (e.g., mice, rabbits, goats), there are several advantages of using avian antibodies (IgY) raised in chickens, including production volumes, costs, and ethical/animal welfare considerations. A further disadvantage of using mammalian IgG in such assays is the potential for agglutination when exposed to rheumatoid factor (RF) in serum. However, when used in the free form the immune complexes formed with avian antibodies have been reported to have less ability than those formed with mammalian antibodies to cause the light scatter which are used for instrument measurement. In addition, when the amount of antigen exceeds the maximum precipitating point in relation to the amount of antibody, there is a rapid decline in the absorbance values of the immune complexes (antigen excess) when IgY is used. However, when avian antibodies are conjugated to a substrate and used in particle enhanced turbidimetric assays (PETIA), these problems are avoided. Here we investigated three clinical assays using chicken antibodies, one using free (unbound) IgY and two with IgY-based PETIA. The IgY PETIA demonstrated a strong scatter response, even at high antigen concentrations in contrast to the steep decline seen with free IgY antibodies. IgY PETIA reagents can provide test results with low coefficient of variation (<1% for duplicate samples). We also investigated the effect of RF on agglutination of mammalian antibodies (IgG from mouse, rabbit, sheep, and human) and chicken antibodies. Whereas agglutination was observed with all the mammalian antibodies in the presence of RF, this was not observed at all with chicken IgY. Our results support the growing body of evidence that chicken egg yolks can thus be a valuable source of antibodies for use in PETIA in clinical laboratories.

Genetics of COVID-19 and myalgic encephalomyelitis/chronic fatigue syndrome: a systematic review

COVID‐19 and ME/CFS present with some similar symptoms, especially physical and mental fatigue. In order to understand the basis of these similarities and the possibility of underlying common genetic components, we performed a systematic review of all published genetic association and cohort studies regarding COVID‐19 and ME/CFS and extracted the genes along with the genetic variants investigated. We then performed gene ontology and pathway analysis of those genes that gave significant results in the individual studies to yield functional annotations of the studied genes using protein analysis through evolutionary relationships (PANTHER) VERSION 17.0 software. Finally, we identified the common genetic components of these two conditions. Seventy‐one studies for COVID‐19 and 26 studies for ME/CFS were included in the systematic review in which the expression of 97 genes for COVID‐19 and 429 genes for ME/CFS were significantly affected. We found that ACE, HLA‐A, HLA‐C, HLA‐DQA1, HLA‐DRB1, and TYK2 are the common genes that gave significant results. The findings of the pathway analysis highlight the contribution of inflammation mediated by chemokine and cytokine signaling pathways, and the T cell activation and Toll receptor signaling pathways. Protein class analysis revealed the contribution of defense/immunity proteins, as well as protein‐modifying enzymes. Our results suggest that the pathogenesis of both syndromes could involve some immune dysfunction.

Clinical utility of circulating calprotectin to assist prediction and monitoring of COVID-19 severity: An Italian study

BACKGROUND

Calprotectin (S100A8/A9) has been identified as a biomarker that can aid in predicting the severity of disease in COVID-19 patients. This study aims to evaluate the correlation between levels of circulating calprotectin (cCP) and the severity of COVID-19.

METHODS

Sera from 245 COVID-19 patients and 110 apparently healthy individuals were tested for calprotectin levels using a chemiluminescent immunoassay (Inova Diagnostics). Intensive care unit (ICU) admission and type of respiratory support administered were used as indicators of disease severity, and their correlation with calprotectin levels was assessed.

RESULTS

Samples from patients in the ICU had a median calprotectin concentration of 11.6 µg/ml as compared to 3.5 µg/ml from COVID-19 patients who were not in the ICU. The median calprotectin concentration in a cohort of healthy individuals collected before the COVID-19 pandemic was 3.0 µg/ml (95% CI: 2.820-2.969 µg/ml). Patients requiring a Venturi mask, continuous positive airway pressure, or orotracheal intubation all had significantly higher values of calprotectin than controls, with the increase of cCP levels proportional to the increasing need of respiratory support.

CONCLUSION

Calprotectin levels in serum correlate well with disease severity and represent a promising serological biomarker for the risk assessment of COVID-19 patients.

Calprotectin and Imbalances between Acute-Phase Mediators Are Associated with Critical Illness in COVID-19

The trajectory from moderate and severe COVID-19 into acute respiratory distress syndrome (ARDS) necessitating mechanical ventilation (MV) is a field of active research. We determined serum levels within 24 h of presentation of 20 different sets of mediators (calprotectin, pro- and anti-inflammatory cytokines, interferons) of patients with COVID-19 at different stages of severity (asymptomatic, moderate, severe and ARDS/MV). The primary endpoint was to define associations with critical illness, and the secondary endpoint was to identify the pathways associated with mortality. Results were validated in serial measurements of mediators among participants of the SAVE-MORE trial. Levels of the proinflammatory interleukin (IL)-8, IL-18, matrix metalloproteinase-9, platelet-derived growth factor (PDGF)-B and calprotectin (S100A8/A9) were significantly higher in patients with ARDS and MV. Levels of the anti-inflammatory IL-1ra and IL-33r were also increased; IL-38 was increased only in asymptomatic patients but significantly decreased in the more severe cases. Multivariate ordinal regression showed that pathways of IL-6, IL-33 and calprotectin were associated with significant probability for worse outcome. Calprotectin was serially increased from baseline among patients who progressed to ARDS and MV. Further research is needed to decipher the significance of these findings compared to other acute-phase reactants, such as C-reactive protein (CRP) or ferritin, for the prognosis and development of effective treatments.

S100A8/A9 in COVID-19 pathogenesis: Impact on clinical outcomes

Coronavirus disease 2019 (COVID-19) has a broad range of clinical manifestations, highlighting the need for specific diagnostic tools to predict disease severity and improve patient prognosis. Recently, calprotectin (S100A8/A9) has been proposed as a potential biomarker for COVID-19, as elevated serum S100A8/A9 levels are associated with critical COVID-19 cases and can distinguish between mild and severe disease states. S100A8/A9 is an alarmin that mediates host proinflammatory responses during infection and it has been postulated that S100A8/A9 modulates the cytokine storm; the hallmark of fatal COVID-19 cases. However, it has yet to be determined if S100A8/A9 is a bona-fide biomarker for COVID-19. S100A8/A9 is widely implicated in a variety of inflammatory conditions, such as cystic fibrosis (CF) and chronic obstructive pulmonary disorder (COPD), as well as pulmonary infectious diseases, including tuberculosis and influenza. Therefore, understanding how S100A8/A9 levels correlate with immune responses during inflammatory diseases is necessary to evaluate its candidacy as a potential COVID-19 biomarker. This review will outline the protective and detrimental roles of S100A8/A9 during infection, summarize the recent findings detailing the contributions of S100A8/A9 to COVID-19 pathogenesis, and highlight its potential as diagnostic biomarker and a therapeutic target for pulmonary infectious diseases, including COVID-19.

Prognostic value of circulating calprotectin levels on the clinical course of COVID-19 differs between serum, heparin, EDTA and citrate sample types

INTRODUCTION

During the recent SARS-CoV-2 pandemic, circulating calprotectin (cCLP) gained interest as biomarker to predict the severity of COVID-19. We aimed to investigate the prognostic value of cCLP measured in serum, heparin, EDTA and citrate plasma.

MATERIALS AND METHODS

COVID-19 patients were prospectively included, in parallel with two SARS-CoV-2 negative control populations. The prognostic value of cCLP was compared with IL-6, CRP, LDH, procalcitonin, and the 4C-mortality score by AUROC analysis.

RESULTS

For the 136 COVID-19 patients, cCLP levels were higher compared to the respective control populations, with significantly higher cCLP levels in serum and heparin than in EDTA or citrate. Higher cCLP levels were obtained for COVID-19 patients with i) severe/critical illness (n = 70), ii) ICU admission (n = 66) and iii) need for mechanical ventilation/ECMO (n = 25), but iv) not in patients who deceased within 30 days (n = 41). The highest discriminatory power (AUC [95% CI]) for each defined outcome was i) CRP (0.835 [0.755-0.914]); ii) EDTA cCLP (0.780 [0.688-0.873]); iii) EDTA cCLP (0.842 [0.758-0.925]) and iv) the 4C-mortality score (0.713 [0.608-0.818]).

CONCLUSION

Measuring cCLP in COVID-19 patients helps the clinician to predict the clinical course of COVID-19. The discriminatory power of EDTA and citrate plasma cCLP levels often outperforms heparin plasma cCLP levels.

Current and novel biomarkers of thrombotic risk in COVID-19: a Consensus Statement from the International COVID-19 Thrombosis Biomarkers Colloquium

Coronavirus disease 2019 (COVID-19) predisposes patients to thrombotic and thromboembolic events, owing to excessive inflammation, endothelial cell activation and injury, platelet activation and hypercoagulability. Patients with COVID-19 have a prothrombotic or thrombophilic state, with elevations in the levels of several biomarkers of thrombosis, which are associated with disease severity and prognosis. Although some biomarkers of COVID-19-associated coagulopathy, including high levels of fibrinogen and D-dimer, were recognized early during the pandemic, many new biomarkers of thrombotic risk in COVID-19 have emerged. In this Consensus Statement, we delineate the thrombotic signature of COVID-19 and present the latest biomarkers and platforms to assess the risk of thrombosis in these patients, including markers of platelet activation, platelet aggregation, endothelial cell activation or injury, coagulation and fibrinolysis as well as biomarkers of the newly recognized post-vaccine thrombosis with thrombocytopenia syndrome. We then make consensus recommendations for the clinical use of these biomarkers to inform prognosis, assess disease acuity, and predict thrombotic risk and in-hospital mortality. A thorough understanding of these biomarkers might aid risk stratification and prognostication, guide interventions and provide a platform for future research.

Fecal Calprotectin as a Predictor of COVID-19 Severity

Coronavirus disease 2019 (COVID-19) is highly transmittable through contact with respiratory droplets. The virus is also shed in fecal matter. Some patients may present with effects in more than one system; however, there are no defined biomarkers that can accurately predict the course or progression of the disease. The present study aimed to estimate the severity of the disease, to correlate the severity of the disease with biochemical predictors, to identify valuable biomarkers indicative of gastrointestinal disease, and to determine the cutoff values. A cross-sectional study was conducted on COVID-19 patients admitted to the Kafrelsheikh University Hospital (isolation unit) between July 10, 2020, and October 30, 2020. The diagnosis of COVID-19 was confirmed via reverse transcription-polymerase chain reaction (RT-PCR), which was employed for the detection of the viral RNA. We conclude that lymphopenia, elevated C-reactive protein (CRP) level, and liver enzymes were among the most important laboratory findings in COVID-19 patients. Statistically significant differences in platelet count, neutrophil count, D-dimer level, and fecal calprotectin levels were observed among patients presenting with chest symptoms only and patients with both chest and gastrointestinal symptoms (p = 0.004; < 0.001; 0.010; 0.003; and < 0.001, respectively). C-reactive protein, D-dimer, and fecal calprotectin levels positively correlated with disease severity. The cutoff value for fecal calprotectin that can predict gastrointestinal involvement in COVID-19 was 165.0, with a sensitivity of 88.1% and a specificity of 76.5%.

Plasma Proteome Fingerprints Reveal Distinctiveness and Clinical Outcome of SARS-CoV-2 Infection

Background: We evaluated how plasma proteomic signatures in patients with suspected COVID-19 can unravel the pathophysiology, and determine kinetics and clinical outcome of the infection. Methods: Plasma samples from patients presenting to the emergency department (ED) with symptoms of COVID-19 were stratified into: (1) patients with suspected COVID-19 that was not confirmed (n = 44); (2) non-hospitalized patients with confirmed COVID-19 (n = 44); (3) hospitalized patients with confirmed COVID-19 (n = 53) with variable outcome; and (4) patients presenting to the ED with minor diseases unrelated to SARS-CoV-2 infection (n = 20). Besides standard of care diagnostics, 177 circulating proteins related to inflammation and cardiovascular disease were analyzed using proximity extension assay (PEA, Olink) technology. Results: Comparative proteome analysis revealed 14 distinct proteins as highly associated with SARS-CoV-2 infection and 12 proteins with subsequent hospitalization (p < 0.001). ADM, IL-6, MCP-3, TRAIL-R2, and PD-L1 were each predictive for death (AUROC curve 0.80–0.87). The consistent increase of these markers, from hospital admission to intensive care and fatality, supported the concept that these proteins are of major clinical relevance. Conclusions: We identified distinct plasma proteins linked to the presence and course of COVID-19. These plasma proteomic findings may translate to a protein fingerprint, helping to assist clinical management decisions.

Elevated fecal and serum calprotectin in COVID-19 are not consistent with gastrointestinal symptoms

Intestinal epithelial cell damage caused by SARS-CoV-2 infection was thought to be associated with gastrointestinal symptoms and decreased fecal consistency. The association of the gastrointestinal symptoms with the COVID-19-mediated inflammatory response triggered by the gastrointestinal immune system was investigated in this paper. Intestinal inflammation marker fecal calprotectin along with serum calprotectin and other inflammatory markers were measured in COVID-19 cases with and without GI manifestations as well as healthy individuals. Analyses were performed to compare COVID-19 patient subgroups and healthy controls and examine the relationship between fecal and serum calprotectin levels with gastrointestinal symptoms and disease severity. COVID-19 patients (n = 70) were found to have markedly elevated median levels of fecal (124.3 vs. 25.0 µg/g; P < 0/0001) and serum calprotectin (3500 vs. 1060 ng/mL; P < 0/0001) compared with uninfected controls. Fecal and serum calprotectin levels were not significantly different between COVID-19 patients who displayed GI symptoms and those who did not. Compared with other acute phase markers, both fecal and serum calprotectin were superior in identifying COVID-19 patients who progressed to severe illness. Although the progression of COVID-19 disease is marked by an elevation of fecal and serum calprotectin, gastrointestinal symptoms or diarrhea were not correlated with calprotectin increase level.

Circulating levels of calprotectin, a signature of neutrophil activation in prediction of severe respiratory failure in COVID-19 patients: a multicenter, prospective study (CalCov study)

OBJECTIVE

Severe COVID-19 is characterized by a dysregulated immune response in which neutrophils play a critical role. Calprotectin reflects neutrophil activation and is involved in the self-amplifying thrombo-inflammatory storm in severe COVID-19. We aimed to evaluate the role of calprotectin in early prediction of severity in COVID-19 patients.

METHODS

This was a multicenter prospective observational study enrolling consecutive adult COVID-19 patients. On arrival to emergency department, blood samples were collected for laboratory tests, including serum calprotectin. The primary outcome was severe respiratory failure requiring invasive mechanical ventilation and the secondary outcome was need for Intensive Care Unit (ICU) admission.

RESULTS

Study population included 395 patients, 57 (14.4%) required invasive mechanical ventilation and 100 (25.3%) were admitted to ICU. Median serum calprotectin levels were significantly higher in intubated (3.73 mg/L vs. 2.63 mg/L; p < 0.001) and ICU patients (3.48 mg/L vs. 2.60 mg/L; p = 0.001). Calprotectin showed a significant accuracy to predict the need for invasive mechanical ventilation (ROC AUC 0.723) and ICU admission (ROC AUC 0.650). In multivariate analysis, serum calprotectin was an independent predictor of invasive mechanical ventilation (OR 1.161) and ICU admission (OR 1.068).

CONCLUSION

Serum calprotectin can be used as an early predictor of severity in COVID-19 patients.

Calprotectin and SARS-CoV-2: A Brief-Report of the Current Literature

In late December 2019, a novel coronavirus (lately referred to as SARS-CoV-2) spread in the city of Wuhan, China, causing an outbreak of unusual viral pneumonia. In many people, the disease is mild and self-limiting, but in a considerable number of patients, the disease may present more severe or even fatal. Therefore, determining which patients are at higher risk of developing a more severe disease is critical. Some studies have been focused on serum and fecal calprotectin to evaluate COVID-19 disease progression and possible complications. Some assumptions can be made: (1) serum calprotectin may efficiently predict the prognosis of COVID-19 patients; (2) fecal calprotectin may appear high in COVID-19 patients due to the double hit mechanism to the intestine (inflammatory and ischemic); (3) a relationship between the complement system and neutrophil activation contributes to the procoagulant status seen in COVID-19 patients; (4) some patients may develop severe gastro-intestinal complications and fecal calprotectin can be used to monitor intestinal disease activity levels.

Oxidative Stress and Inflammatory Biomarkers for the Prediction of Severity and ICU Admission in Unselected Patients Hospitalized with COVID-19

Objective: We aimed to investigate the prognostic performances of oxidative stress (OS), inflammatory and cell activation biomarkers measured at admission in COVID-19 patients. Design: retrospective monocentric study. Setting: patients with suspected SARS-CoV-2 infection (COVID-19) admitted to the hospital. Patients: One hundred and sixty documented and unselected COVID-19-patients. Disease severity (from mild to critical) was scored according to NIH’s classification. Interventions: none. Measurements and main results: We measured OS biomarkers (thiol, advanced oxidation protein products (AOPP), ischemia-modified albumin (IMA)), inflammation biomarkers (interleukin-6 (IL-6), presepsin) and cellular activation biomarkers (calprotectin) in plasma at admission. Thiol concentrations decreased while IMA, IL-6, calprotectin and PSEP increased with disease severity in COVID-19 patients and were associated with increased O₂ needs and ICU admission. The best area under the receiver-operating-characteristics curve (AUC) for the prediction of ICU admission was for thiol (AUC = 0.762). A thiol concentration <154 µmol/L was predictive for ICU admission (79.7% sensitivity, 64.6% specificity, 58.8% positive predictive value, 78.9% negative predictive value). In a stepwise logistic regression, we found that being overweight, having dyspnoea, and thiol and IL-6 plasmatic concentrations were independently associated with ICU admission. In contrast, calprotectin was the best biomarker to predict mortality (AUC = 0.792), with an optimal threshold at 24.1 mg/L (94.1% sensitivity, 64.9% specificity, 97.1% positive predictive value and 98.9% negative predictive value), and survival curves indicated that high IL-6 and calprotectin concentrations were associated with a significantly increased risk of mortality. Conclusions: Thiol measurement at admission is a promising tool to predict ICU admission in COVID-19-patients, whereas IL-6 and calprotectin measurements effectively predict mortality.

High fecal calprotectin levels are associated with SARS-CoV-2 intestinal shedding in COVID-19 patients: A proof-of-concept study

BACKGROUND

One third of coronavirus disease 2019 (COVID-19) patients have gastrointestinal symptoms. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA has been detected in stool samples of approximately 50% of COVID-19 individuals. Fecal calprotectin is a marker of gastrointestinal inflammation in the general population.

AIM

To investigate if fecal calprotectin correlates with SARS-CoV-2 intestinal shedding in COVID-19 patients with pneumonia.

METHODS

Patients with SARS-CoV-2 pneumonia admitted to the Infectious Disease Unit (University Hospital of Trieste, Italy) from September to November 2020 were consecutively enrolled in the study. Fecal samples were collected and analyzed for quantification of fecal calprotectin (normal value < 50 mg/kg) and SARS-CoV-2 RNA presence by polymerase chain reaction (PCR). Inter-group differences were determined between patients with and without diarrhea and patients with and without detection of fecal SARS-CoV-2.

RESULTS

We enrolled 51 adults (40 males) with SARS-CoV-2 pneumonia. Ten patients (20%) presented with diarrhea. Real-time-PCR of SARS-CoV-2 in stools was positive in 39 patients (76%), in all patients with diarrhea (100%) and in more than two thirds (29/41, 71%) of patients without diarrhea. Obesity was one of the most common comorbidities (13 patients, 25%); all obese patients (100%) (P = 0.021) tested positive for fecal SARS-CoV-2. Median fecal calprotectin levels were 60 mg/kg [interquartile range (IQR) 21; 108]; higher fecal calprotectin levels were found in the group with SARS-CoV-2 in stools (74 mg/kg, IQR 29; 132.5) compared to the group without SARS-CoV-2 (39 mg/kg, IQR 14; 71) (P < 0.001).

CONCLUSION

High fecal calprotectin levels among COVID-19 patients correlate with SARS-CoV-2 detection in stools supporting the hypothesis that this virus can lead to bowel inflammation and potentially to the 'leaky gut' syndrome.

ICODE: the international COVID-19 thrombosis biomarkers colloquium-novel soluble biomarkers: circulating cell-free nucleic acids and other molecules

This article summarizes the evidence derived from clinical (observational) studies describing novel soluble biomarkers in COVID-19. Our goal was to stimulate further research (preclinical as well as clinical studies) and therefore we discuss potential prognostic value, but also technical details, such as sample preparation. A table provides an overview of the described biomarkers measured in plasma, serum or other (namely bronchoalveolar) fluids.

Parameters associated with diagnosis of COVID-19 in emergency department

OBJECTIVES

We designed this study to identify laboratory and radiological parameters, which could be useful to guide the clinician, in the evaluation of a suspected case of coronavirus disease 19 (COVID-19).

METHODS

This retrospective, observational, single-center-study recruited patients with a suspect of COVID-19 data were extracted from electronic medical records using a standardized data collection form.

RESULTS

A total of 566 patients with suspect COVID-19 infection were enrolled (280 were COVID-19+). The COVID-19 population was characterized with bilateral-pneumonia, a lower count of neutrophil, lymphocyte and monocyte, a lower neutrophil to lymphocyte-ratio (NLR). Lower of platelet count, d-dimer, troponin I, and serum calcium were in COVID-19 patients. The occurrence of COVID-19 diagnosis increased, independently of other variables, with pneumonia (odds ratio [OR]: 3.60; p < .001), neutrophil below normal range (OR: 4.15; p < .05), lactate dehydrogenase (OR: 2.09; p < .01) and sodium above normal range (OR: 2.34; p < .01). In patients with possible respiratory acute affections we found a higher neutrophil, higher monocyte, a higher NLR and a more elevation in d-dimer. In the Sepsis group showed higher level of white blood cell, C-reactive protein, d-dimer, and procalcitonin.

CONCLUSIONS

Our study confirms that patients with COVID-19 have typical radiological and laboratory characteristics. The parameters highlighted in the study can help identify COVID-19 patients, also highlighting which are the main differential diagnoses to be made and the parameters that facilitate the differential diagnosis.

Circulating Calprotectin as a Biomarker of COVID-19 Severity

INTRODUCTION

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although demographic and clinical parameters such as sex, age, comorbidities, genetic background and various biomarkers have been identified as risk factors, there is an unmet need to predict the risk and onset of severe inflammatory disease leading to poor clinical outcomes. In addition, very few mechanistic biomarkers are available to inform targeted treatment of severe (auto)-inflammatory conditions associated with COVID-19. Calprotectin, also known as S100A8/S100A9, MRP8/14 (Myeloid-Related Protein) or L1, is a heterodimer involved in neutrophil-related inflammatory processes. In COVID-19 patients, calprotectin levels were reported to be associated with poor clinical outcomes such as significantly reduced survival time, especially in patients with severe pulmonary disease.

AREAS COVERED

Pubmed was searched using the following keywords: Calprotectin + COVID19, S100A8/A9 + COVID19, S100A8 + COVID-19, S100A9 + COVID-19, MRP8/14 + COVID19; L1 + COVID-19 between May 2020 and 8 March 2021. The results summarized in this review provide supporting evidence and propose future directions that define calprotectin as an important biomarker in COVID-19.

EXPERT OPINION

Calprotectin represents a promising serological biomarker for the risk assessment of COVID-19 patients.

Serum calprotectin as a novel biomarker for severity of COVID-19 disease

Background

Some biomarkers have been reported to be related to the prognosis of the coronavirus disease 2019 (COVID-19). There are sparse data regarding the prognostic value of serum calprotectin in COVID-19 patients.

Aims

This study aimed to investigate the relationship between serum calprotectin level and clinical severity of COVID-19 disease in hospitalized patients.

Methods

This retrospective cross-sectional cohort study included 80 consecutive hospitalized patients with confirmed diagnosis of COVID-19. The study population was divided into two groups as patients hospitalized in the intensive care unit (ICU) and patients hospitalized but not in the ICU. The serum calprotectin levels, other laboratory, and clinical parameters were compared between groups.

Results

The mean age of the patients was 66.5 ± 15.7 years. Of the patients, 42 were in the ICU and 38 were not. Serum calprotectin level and acute-phase reactants such as C-reactive protein, procalcitonin, ferritin, fibrinogen, and white blood cell were significantly higher in ICU patients than in non-ICU patients. ROC curve analysis identified that serum calprotectin level was a predictor for ICU requirement with an area under the curve of 0.641 (p = 0.031). Logistic regression analysis revealed that serum calprotectin was a significant determinant for whether or not patient required the ICU.

Conclusions

These findings demonstrate that serum calprotectin level seems to be a useful biomarker that can predict the severity of COVID-19 disease. Serum calprotectin is a significant predictor of ICU requirement in patients with COVID-19.

Calprotectin, an Emerging Biomarker of Interest in COVID-19: A Systematic Review and Meta-Analysis

COVID-19 has been shown to present with varied clinical course, necessitating a need for more specific diagnostic tools that could identify severe cases and predict outcomes during COVID-19 infection. Recent evidence has shown an expanded potential role for calprotectin, both as a diagnostic tool and also as a tool in stratifying COVID-19 patients in terms of severity. Therefore, this systematic review and meta-analysis aims to evaluate the levels of calprotectin in severe and non-severe COVID-19 and also identify the implication of raised calprotectin levels. MEDLINE, EMBASE, The Cochrane Library, Web of science and MedRxiv were searched. Meta-analysis was done to compare the serum/fecal levels of calprotectin between severe and non-severe COVID-19 infections. A total of ten studies included in the review (eight had quantitative data while two were qualitative). A pooled analysis of the eight studies from 613 patients who were RT-PCR positive for COVID-19 (average age = 55 years; 52% males) showed an overall estimate as 1.34 (95%CI: 0.77, 1.91). In conclusion, calprotectin levels have been demonstrated to be significantly elevated in COVID-19 patients who develop the severe form of the disease, and it also has prognostic importance.