Circulating Osteopontin Levels and Outcomes in Patients Hospitalized for COVID-19

Inflammation and Elevated Osteopontin in Plasma and CSF in Cerebral Malaria Compared to Plasmodium-Negative Neurological Infections

Cerebral malaria in young African children is associated with high mortality, and persisting neurological deficits often remain in survivors. Sequestered Plasmodium-infected red blood cells lead to cerebrovascular inflammation and subsequent neuroinflammation. Brain inflammation can play a role in the pathogenesis of neurologic sequelae. Therefore, we assessed a select set of proinflammatory analytes (IP10, IL23, MIP3α, GRO, MCP-1, and osteopontin in both the plasma and cerebrospinal fluid(CSF) of Zambian children with cerebral malaria and compared this with children with neurological symptoms that were negative for Plasmodium falciparum (non-cerebral malaria). Several similarities in plasma and CSF levels were found, as were some striking differences. We confirmed that IP10 levels were higher in the plasma of cerebral malaria patients, but this was not found in CSF. Levels of osteopontin were elevated in both the plasma and CSF of CM patients compared to the non-CM patients. These results show again a highly inflammatory environment in both groups but a different profile for CM when compared to non-cerebral malaria. Osteopontin may play an important role in neurological inflammation in CM and the resulting sequelae. Therefore, osteopontin could be a valid target for further biomarker research and potentially for therapeutic interventions in neuroinflammatory infections.

Osteopontin: A Novel Therapeutic Target for Respiratory Diseases

Osteopontin (OPN) is a multifunctional phosphorylated protein that is involved in physiological and pathological events. Emerging evidence suggests that OPN also plays a critical role in the pathogenesis of respiratory diseases. OPN can be produced and secreted by various cell types in lungs and overexpression of OPN has been found in acute lung injury/acute respiratory distress syndrome (ALI/ARDS), pulmonary hypertension (PH), pulmonary fibrosis diseases, lung cancer, lung infection, chronic obstructive pulmonary disease (COPD), and asthma. OPN exerts diverse effects on the inflammatory response, immune cell activation, fibrosis and tissue remodeling, and tumorigenesis of these respiratory diseases, and genetic and pharmacological moudulation of OPN exerts therapeutic effects in the treatment of respiratory diseases. In this review, we summarize the recent evidence of multifaceted roles and underlying mechanisms of OPN in these respiratory diseases, and targeting OPN appears to be a potential therapeutic intervention for these diseases.

Immunoregulatory Roles of Osteopontin in Diseases

Osteopontin (OPN) is a multifunctional protein that plays a pivotal role in the immune system. It is involved in various biological processes, including cell adhesion, migration and survival. The study of the immunomodulatory effects of OPN is of paramount importance due to its potential therapeutic applications. A comprehensive understanding of how OPN regulates the immune response could pave the way for the development of novel treatments for a multitude of diseases, including autoimmune disorders, infectious diseases and cancer. Therefore, in the following paper, we provide a systematic overview of OPN and its immunoregulatory roles in various diseases, laying the foundation for the development of OPN-based therapies in the future.

High Plasma Osteopontin Levels Are Associated with Serious Post-Acute-COVID-19-Related Dyspnea

COVID-19 survivors commonly report persistent symptoms. In this observational study, we investigated the link between osteopontin (OPN) and post-acute COVID-19 symptoms and lung functional/imaging abnormalities. We recorded symptoms and lung imaging/functional data from previously hospitalized COVID-19 patients, who were followed for 4-84 weeks (122 patients/181 visits) post-symptom onset at our outpatient clinic. Circulating OPN was determined using ELISA. Plasma OPN levels were higher in symptomatic patients (compared with the asymptomatic ones); those with dyspnea (compared with those without dyspnea);those with a combination of serious symptoms, i.e., the presence of at least one of the following: dyspnea, fatigue and muscular weakness (compared with those with none of these symptoms); and those with dyspnea and m-MRC > 1 (compared with those with m-MRC = 0-1). Plasma OPN levels were inversely correlated with EQ-VAS (visual analog scale of the EQ-5D-5L health-related quality-of-life questionnaire) values. High-resolution CT or diffusion lung capacity (DLCO) findings were not related to circulating OPN. In the multiple logistic regression, the presence of symptoms, dyspnea, or the combination of serious symptoms were linked to female gender, increased BMI and pre-existing dyspnea (before the acute disease), while increased plasma OPN levels, female gender and pre-existing dyspnea with m-MRC > 1 were independently associated with severe post-COVID-19 dyspnea (m-MRC > 1). Using a correlation matrix to investigate multiple correlations between EQ-VAS, OPN and epidemiological data, we observed an inverse correlation between the OPN and EQ-VAS values. Increased circulating OPN was linked to the persistence of severe exertional dyspnea and impaired quality of life in previously hospitalized COVID-19 patients.

Circulating markers of extracellular matrix remodelling in severe COVID-19 patients

BACKGROUND

Abnormal remodelling of the extracellular matrix (ECM) has generally been linked to pulmonary inflammation and fibrosis and may also play a role in the pathogenesis of severe COVID-19. To further elucidate the role of ECM remodelling and excessive fibrogenesis in severe COVID-19, we examined circulating levels of mediators involved in various aspects of these processes in COVID-19 patients.

METHODS

Serial blood samples were obtained from two cohorts of hospitalised COVID-19 patients (n = 414). Circulating levels of ECM remodelling mediators were quantified by enzyme immunoassays in samples collected during hospitalisation and at 3-month follow-up. Samples were related to disease severity (respiratory failure and/or treatment at the intensive care unit), 60-day total mortality and pulmonary pathology after 3-months. We also evaluated the direct effect of inactivated SARS-CoV-2 on the release of the different ECM mediators in relevant cell lines.

RESULTS

Several of the measured markers were associated with adverse outcomes, notably osteopontin (OPN), S100 calcium-binding protein A12 and YKL-40 were associated with disease severity and mortality. High levels of ECM mediators during hospitalisation were associated with computed tomography thorax pathology after 3-months. Some markers (i.e. growth differential factor 15, galectin 3 and matrix metalloproteinase 9) were released from various relevant cell lines (i.e. macrophages and lung cell lines) in vitro after exposure to inactivated SARS-CoV-2 suggesting a direct link between these mediators and the causal agent of COVID-19.

CONCLUSION

Our findings highlight changes to ECM remodelling and particularly a possible role of OPN, S100A12 and YKL-40 in the pathogenesis of severe COVID-19.

The Role of Osteopontin in Respiratory Health and Disease

The biological functions of osteopontin (OPN) are diverse and specific to physiological and pathophysiological conditions implicated in inflammation, biomineralization, cardiovascular diseases, cellular viability, cancer, diabetes, and renal stone disease. We aimed to present the role of OPN in respiratory health and disease. OPN influences the immune system and is a chemo-attractive protein correlated with respiratory disease severity. There is evidence that OPN can advance the disease stage associated with its fibrotic, inflammatory, and immune functions. OPN contributes to eosinophilic airway inflammation. OPN can destroy the lung parenchyma through its neutrophil influx and fibrotic mechanisms, linking OPN to at least one of the two major chronic obstructive pulmonary disease phenotypes. Respiratory diseases that involve irreversible lung scarring, such as idiopathic pulmonary disease, are linked to OPN, with protein levels being overexpressed in individuals with severe or advanced stages of the disorders and considerably lower levels in those with less severe symptoms. OPN plays a significant role in lung cancer progression and metastasis. It is also implicated in the pathogenesis of pulmonary hypertension, coronavirus disease 2019, and granuloma generation.

Case report: Fatal lung hyperinflammation in a preterm newborn with SARS-CoV-2 infection

Vertical transmission of SARS-CoV-2 from mother to fetus is widely accepted. Whereas most infected neonates present with mild symptoms or are asymptomatic, respiratory distress syndrome (RDS) and abnormal lung images are significantly more frequent in COVID-19 positive neonates than in non-infected newborns. Fatality is rare and discordant meta-analyses of case reports and series relating perinatal maternal COVID-19 status to neonatal disease severity complicate their extrapolation as prognostic indicators. A larger database of detailed case reports from more extreme cases will be required to establish therapeutic guidelines and allow informed decision making. Here we report an unusual case of a 28 weeks' gestation infant with perinatally acquired SARS-CoV-2, who developed severe protracted respiratory failure. Despite intensive care from birth with first line anti-viral and anti-inflammatory therapy, respiratory failure persisted, and death ensued at 5 months. Lung histopathology showed severe diffuse bronchopneumonia, and heart and lung immunohistochemistry confirmed macrophage infiltration, platelet activation and neutrophil extracellular trap formation consistent with late multisystem inflammation. To our knowledge, this is the first report of SARS CoV-2 pulmonary hyperinflammation in a preterm newborn with fatal outcome.

Organokines in COVID-19: A Systematic Review

Coronavirus disease 2019 (COVID-19) is a viral infection caused by SARS-CoV-2 that induces a generalized inflammatory state. Organokines (adipokines, osteokines, myokines, hepatokines, and cardiokines) can produce beneficial or harmful effects in this condition. This study aimed to systematically review the role of organokines on COVID-19. PubMed, Embase, Google Scholar, and Cochrane databases were searched, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and 37 studies were selected, comprising more than 2700 individuals infected with the virus. Among COVID-19 patients, organokines have been associated with endothelial dysfunction and multiple organ failure due to augmented cytokines and increased SARS-CoV-2 viremia. Changes in the pattern of organokines secretion can directly or indirectly contribute to aggravating the infection, promoting immune response alterations, and predicting the disease progression. These molecules have the potential to be used as adjuvant biomarkers to predict the severity of the illness and severe outcomes.

COVID-19 Biomarkers at the Crossroad between Patient Stratification and Targeted Therapy: The Role of Validated and Proposed Parameters

Clinical knowledge about SARS-CoV-2 infection mechanisms and COVID-19 pathophysiology have enormously increased during the pandemic. Nevertheless, because of the great heterogeneity of disease manifestations, a precise patient stratification at admission is still difficult, thus rendering a rational allocation of limited medical resources as well as a tailored therapeutic approach challenging. To date, many hematologic biomarkers have been validated to support the early triage of SARS-CoV-2-positive patients and to monitor their disease progression. Among them, some indices have proven to be not only predictive parameters, but also direct or indirect pharmacological targets, thus allowing for a more tailored approach to single-patient symptoms, especially in those with severe progressive disease. While many blood test-derived parameters quickly entered routine clinical practice, other circulating biomarkers have been proposed by several researchers who have investigated their reliability in specific patient cohorts. Despite their usefulness in specific contexts as well as their potential interest as therapeutic targets, such experimental markers have not been implemented in routine clinical practice, mainly due to their higher costs and low availability in general hospital settings. This narrative review will present an overview of the most commonly adopted biomarkers in clinical practice and of the most promising ones emerging from specific population studies. Considering that each of the validated markers reflects a specific aspect of COVID-19 evolution, embedding new highly informative markers into routine clinical testing could help not only in early patient stratification, but also in guiding a timely and tailored method of therapeutic intervention.

Evaluation of IGFBP5 expression and plasma osteopontin level in COVID-19 patients

PURPOSE

The aim of this study is to investigate insulin-like growth factor binding protein 5 (IGFBP5) expression in coronavirus disease 2019 (COVID-19) patients and its relationships with COVID-19 laboratory findings and plasma osteopontin (OPN) levels.

MATERIALS AND METHODS

We enrolled 60 patients with COVID-19 and 30 healthy individuals in this study. mRNA expression of IGFBP5 was measured by RT-PCR. Plasma OPN levels were measured via the ELISA method.

RESULTS

Plasma OPN levels were higher and IGFBP5 expression levels were lower in COVID-19 patients than in the healthy individuals (p ​= ​0.0057 and p ​= ​0.0142, respectively). Critically ill patients had higher OPN and lower IGFBP5 than non-critically ill patients. Patients with affected lungs demonstrated increased OPN and decreased IGFBP5 (p ​= ​0.00032 and p ​= ​0.044, respectively). Receiver operating characteristic (ROC) analysis indicated that IGFBP5 expression and OPN levels can be used discriminate non-critically from critically ill patients (p ​= ​0.049; p ​= ​0.0016, respectively).

CONCLUSION

This study demonstrated that patients with a poor prognosis had increased OPN and decreased IGFBP5. High values of OPN and low values of IGFBP5 may be considered as signs of disease severity. Tissue-specific IGFBP5 expression may contribute to understanding the role of IGFBP5 in the lungs in COVID-19 cases.

Baseline Plasma Osteopontin Protein Elevation Predicts Adverse Outcomes in Hospitalized COVID-19 Patients

More than three years have passed since the first case, and COVID-19 is still a health concern, with several open issues such as the lack of reliable predictors of a patient’s outcome. Osteopontin (OPN) is involved in inflammatory response to infection and in thrombosis driven by chronic inflammation, thus being a potential biomarker for COVID-19. The aim of the study was to evaluate OPN for predicting negative (death or need of ICU admission) or positive (discharge and/or clinical resolution within the first 14 days of hospitalization) outcome. We enrolled 133 hospitalized, moderate-to-severe COVID-19 patients in a prospective observational study between January and May 2021. Circulating OPN levels were measured by ELISA at admission and at day 7. The results showed a significant correlation between higher plasma concentrations of OPN at hospital admission and a worsening clinical condition. At multivariate analysis, after correction for demographic (age and gender) and variables of disease severity (NEWS2 and PiO2/FiO2), OPN measured at baseline predicted an adverse prognosis with an odds ratio of 1.01 (C.I. 1.0–1.01). At ROC curve analysis, baseline OPN levels higher than 437 ng/mL predicted a severe disease evolution with 53% sensitivity and 83% specificity (area under the curve 0.649, p = 0.011, likelihood ratio of 1.76, (95% confidence interval (CI): 1.35–2.28)). Our data show that OPN levels determined at the admission to hospital wards might represent a promising biomarker for early stratification of patients’ COVID-19 severity. Taken together, these results highlight the involvement of OPN in COVID-19 evolution, especially in dysregulated immune response conditions, and the possible use of OPN measurements as a prognostic tool in COVID-19.

Thiol-ene-based microfluidic chips for glycopeptide enrichment and online digestion of inflammation-related proteins osteopontin and immunoglobulin G

Proteins, and more specifically glycoproteins, have been widely used as biomarkers, e.g., to monitor disease states. Bottom-up approaches based on mass spectrometry (MS) are techniques commonly utilized in glycoproteomics, involving protein digestion and glycopeptide enrichment. Here, a dual function polymeric thiol-ene-based microfluidic chip (TE microchip) was applied for the analysis of the proteins osteopontin (OPN) and immunoglobulin G (IgG), which have important roles in autoimmune diseases, in inflammatory diseases, and in coronavirus disease 2019 (COVID-19). TE microchips with larger internal surface features immobilized with trypsin were successfully utilized for OPN digestion, providing rapid and efficient digestion with a residence time of a few seconds. Furthermore, TE microchips surface-modified with ascorbic acid linker (TEA microchip) have been successfully utilized for IgG glycopeptide enrichment. To illustrate the use of the chips for more complex samples, they were applied to enrich IgG glycopeptides from human serum samples with antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The dual functional TE microchips could provide high throughput for online protein digestion and glycopeptide enrichment, showing great promise for future extended applications in proteomics and the study of related diseases.

Soluble Urokinase Plasminogen Activator Receptor and Venous Thromboembolism in COVID-19

Background Venous thromboembolism (VTE) contributes significantly to COVID-19 morbidity and mortality. The urokinase receptor system is involved in the regulation of coagulation. Levels of soluble urokinase plasminogen activator receptor (suPAR) reflect hyperinflammation and are strongly predictive of outcomes in COVID-19. Whether suPAR levels identify patients with COVID-19 at risk for VTE is unclear. Methods and Results We leveraged a multinational observational study of patients hospitalized for COVID-19 with suPAR and D-dimer levels measured on admission. In 1960 patients (mean age, 58 years; 57% men; 20% Black race), we assessed the association between suPAR and incident VTE (defined as pulmonary embolism or deep vein thrombosis) using logistic regression and Fine-Gray modeling, accounting for the competing risk of death. VTE occurred in 163 (8%) patients and was associated with higher suPAR and D-dimer levels. There was a positive association between suPAR and D-dimer (β=7.34; P=0.002). Adjusted for clinical covariables, including D-dimer, the odds of VTE were 168% higher comparing the third with first suPAR tertiles (adjusted odds ratio, 2.68 [95% CI, 1.51-4.75]; P<0.001). Findings were consistent when stratified by D-dimer levels and in survival analysis accounting for death as a competing risk. On the basis of predicted probabilities from random forest, a decision tree found the combined D-dimer <1 mg/L and suPAR <11 ng/mL cutoffs, identifying 41% of patients with only 3.6% VTE probability. Conclusions Higher suPAR was associated with incident VTE independently of D-dimer in patients hospitalized for COVID-19. Combining suPAR and D-dimer identified patients at low VTE risk. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04818866.

Induction of a Cytokine Storm Involves Suppression of the Osteopontin-Dependent TH1 Response

Cytokine release syndromes represent a severe turn in certain disease states, which may be caused by several infections, including those with the virus SARS-CoV-2. This inefficient, even harmful, immune response has been associated with a broad release of chemokines. Although a cellular (type I) immune reaction is efficacious against viral infections, we noted a type I deficit in the cytokine patterns produced by cytokine storms of all reported etiologies. Agents including lipopolysaccharide (LPS, bacterial), anti-CD3 (antibody) and a version of the prominent SARS-CoV-2 viral surface molecule, Spike Glycoprotein, were individually sufficient to induce IL-6 and multiple chemokines in mice. They failed to upregulate the TH1 inducer cytokine Osteopontin, and the pathophysiologic triggers actually suppressed the PMA-induced Osteopontin secretion from monocytic cells. Osteopontin administration partially reversed the chemokine elevation, more effectively so in a mouse strain with TH1 bias. Corroboration was obtained from the inverse correlation in the levels of IL-6 and Osteopontin in plasma samples from acute COVID-19 patients. We hypothesize that the inhibition of Osteopontin by SARS-CoV-2 Spike Glycoprotein or LPS represents an immune evasion mechanism employed by the pathogens of origin. The ensuing dysfunctional inflammatory response promotes a vicious cycle of amplification, resulting in a cytokine storm. This article is protected by copyright. All rights reserved.

Biomarkers Associated with Cardiovascular Disease in COVID-19

Coronavirus disease-19 (COVID-19) emerged late December 2019 in the city of Wuhan, China and has since spread rapidly all over the world causing a global pandemic. While the respiratory system is the primary target of disease manifestation, COVID-19 has been shown to also affect several other organs, making it a rather complex, multi-system disease. As such, cardiovascular involvement has been a topic of discussion since the beginning of the COVID-19 pandemic, primarily due to early reports of excessive myocardial injury in these patients. Treating physicians are faced with multiple challenges in the management and early triage of patients with COVID-19, as disease severity is highly variable ranging from an asymptomatic infection to critical cases rapidly deteriorating to intensive care treatment or even fatality. Laboratory biomarkers provide important prognostic information which can guide decision making in the emergency department, especially in patients with atypical presentations. Several cardiac biomarkers, most notably high-sensitive cardiac troponin (hs-cTn) and N-terminal pro-B-type natriuretic peptide (NT-proBNP), have emerged as valuable predictors of prognosis in patients with COVID-19. The purpose of this review was to offer a concise summary on prognostic cardiac biomarkers in COVID-19 and discuss whether routine measurements of these biomarkers are warranted upon hospital admission.

Naïve Human Macrophages Are Refractory to SARS-CoV-2 Infection and Exhibit a Modest Inflammatory Response Early in Infection

Involvement of macrophages in the SARS-CoV-2-associated cytokine storm, the excessive secretion of inflammatory/anti-viral factors leading to the acute respiratory distress syndrome (ARDS) in COVID-19 patients, is unclear. In this study, we sought to characterize the interplay between the virus and primary human monocyte-derived macrophages (MDM). MDM were stimulated with recombinant IFN-α and/or infected with either live or UV-inactivated SARS-CoV-2 or with two reassortant influenza viruses containing external genes from the H1N1 PR8 strain and heterologous internal genes from a highly pathogenic avian H5N1 or a low pathogenic human seasonal H1N1 strain. Virus replication was monitored by qRT-PCR for the E viral gene for SARS-CoV-2 or M gene for influenza and TCID50 or plaque assay, and cytokine levels were assessed semiquantitatively with qRT-PCR and a proteome cytokine array. We report that MDM are not susceptible to SARS-CoV-2 whereas both influenza viruses replicated in MDM, albeit abortively. We observed a modest cytokine response in SARS-CoV-2 exposed MDM with notable absence of IFN-β induction, which was instead strongly induced by the influenza viruses. Pre-treatment of MDM with IFN-α enhanced proinflammatory cytokine expression upon exposure to virus. Together, the findings concur that the hyperinflammation observed in SARS-CoV-2 infection is not driven by macrophages.