DEspRhigh neutrophils are associated with critical illness in COVID-19

U-shaped relationship found between fibrinogen-to-albumin ratio and systemic inflammation response index in osteoporotic fracture patients

The relationship between the Systemic Inflammatory Response Index (SIRI) and the Fibrinogen-to-albumin ratio (FAR) has not been extensively investigated. The objective of this study was to determine the independent relationship between FAR and SIRI in people with osteoporotic fractures (OPF). A cross-sectional study was conducted using retrospective data from 3431 hospitalized OPF patients. The exposure variable in this study was the baseline FAR, while the outcome variable was the SIRI. Covariates, including age, gender, BMI, and other clinical and laboratory factors, were adjusted. Cross-correlation analysis and linear regression models were applied. The generalized additive model (GAM) investigated non-linear relationships. Adjusted analysis revealed an independent negative association between FAR and SIRI in OPF patients (β = - 0.114, p = 0.00064, 95% CI - 0.180, - 0.049). A substantial U-shaped association between FAR and SIRI was shown using GAM analysis (p < 0.001). FAR and SIRI indicated a negative association for FAR below 6.344% and a positive correlation for FAR over 6.344%. The results of our study revealed a U-shaped relationship between SIRI and FAR. The lowest conceivable FAR for a bone-loose inflammatory disease might be 6.344%, suggesting that this has particular significance for the medical diagnosis and therapy of persons with OPF. Consequently, the term "inflammatory trough" is proposed. These results offer fresh perspectives on controlling inflammation in individuals with OPF and preventing inflammatory osteoporosis.

Neutrophil heterogeneity and aging: implications for COVID-19 and wound healing

Neutrophils play a critical role in the immune response to infection and tissue injury. However, recent studies have shown that neutrophils are a heterogeneous population with distinct subtypes that differ in their functional properties. Moreover, aging can alter neutrophil function and exacerbate immune dysregulation. In this review, we discuss the concept of neutrophil heterogeneity and how it may be affected by aging. We then examine the implications of neutrophil heterogeneity and aging for COVID-19 pathogenesis and wound healing. Specifically, we summarize the evidence for neutrophil involvement in COVID-19 and the potential mechanisms underlying neutrophil recruitment and activation in this disease. We also review the literature on the role of neutrophils in the wound healing process and how aging and neutrophil heterogeneity may impact wound healing outcomes. Finally, we discuss the potential for neutrophil-targeted therapies to improve clinical outcomes in COVID-19 and wound healing.

The double-edged role of neutrophil heterogeneity in inflammatory diseases and cancers

Neutrophils are important immune cells act as the body's first line of defense against infection and respond to diverse inflammatory cues. Many studies have demonstrated that neutrophils display plasticity in inflammatory diseases and cancers. Clarifying the role of neutrophil heterogeneity in inflammatory diseases and cancers will contribute to the development of novel treatment strategies. In this review, we have presented a review on the development of the understanding on neutrophil heterogeneity from the traditional perspective and a high-resolution viewpoint. A growing body of evidence has confirmed the double-edged role of neutrophils in inflammatory diseases and tumors. This may be due to a lack of precise understanding of the role of specific neutrophil subsets in the disease. Thus, elucidating specific neutrophil subsets involved in diseases would benefit the development of precision medicine. Thusly, we have summarized the relevance and actions of neutrophil heterogeneity in inflammatory diseases and cancers comprehensively. Meanwhile, we also discussed the potential intervention strategy for neutrophils. This review is intended to deepen our understanding of neutrophil heterogeneity in inflammatory diseases and cancers, while hold promise for precise treatment of neutrophil-related diseases.

The influence of physical fatigue on telephone-based neuropsychological test performance in COVID-19 survivors

Fatigue has been characterized as a post COVID-19 condition known to persist months after SARS-CoV-2 infection. COVID-19 has been reported to be associated with impaired cognitive function, including disorders in attention, memory, information processing, and executive functions. The objective of this study was to determine if post-COVID fatigue, manifested as tiredness while performing low-intensity physical activity, has a detrimental effect on neuropsychological performance, to achieve this, we randomly selected 20 participants with post-COVID fatigue and 20 SARS-CoV-2 negative age-matched controls from a database of 360 residents of Tijuana, Baja California in a cross-sectional study design. All 40 participants responded to a health survey, along with a neuropsychological assessment test via telephone call. Statistical analysis was performed using a multiple linear regression model including the following independent variables: study condition (post-COVID fatigue or negative control), sex, age, years of education, hypertension, asthma, administration of supplemental oxygen during COVID-19 recovery, and the hour at which the evaluation started. Significant regression analysis was obtained for all global parameters of the assessment, including BANFE-2 score (p = 0.021, R² Adj. = 0.263), NEUROPSI score (p = 0.008, R² Adj. = 0.319), and total errors (p = 0.021, R² Adj. = 0.263), with significant regression coefficients for study condition on two global parameters, BANFE-2 score (p = 0.028, β = - 0.371) and NEUROPSI score (p = 0.010, β = -0.428). These findings suggest that the presence of post-COVID fatigue is a factor associated with a decrease in neuropsychological performance.

Neurological Diseases Define the Cytokine Profile in CFS during SARS-CoV-2 Infection in Highly Ill Patients

Neuroinflammation is critical in developing and progressing neurological diseases. The underlying pro-inflammatory cytokine expression combined with additional mechanisms in the neuropathology, such as oxidative stress, brain-blood barrier damage, and endothelial dysfunction, could contribute to the susceptibility to developing severe COVID-19. The physiopathology of SARS-CoV-2 and other human coronaviruses (H-CoVs) has not been completely understood; however, they have all been linked to a disproportionated response of the immune system, particularly an exacerbated cytokine production and the dysregulation of total cell counts. In this article, based on the compilation of studies reported by our working group regarding COVID-19 and neurological diseases, we propose that the inflammation observed in the central nervous system, through a CSF analysis, could be conditioned by neurological disease(s) and enhanced by COVID-19. Therefore, it is necessary to determine the cytokine profile in different neurological disorders to propose adequate treatments and avoid severe forms of the disease in these patients.

Circulating neutrophil extracellular trap (NET)-forming 'rogue' neutrophil subset, immunotype [DEspR + CD11b +], mediate multi-organ failure in COVID-19-an observational study

Background

Cumulative research show association of neutrophils and neutrophil extracellular traps (NETs) with poor outcomes in severe COVID-19. However, to date, there is no curative intent therapy able to block neutrophil/NETs-mediated progression of multi-organ dysfunction. Because of emerging neutrophil heterogeneity, the study of subsets of circulating NET-forming neutrophils [NET + Ns] as mediators of multi-organ failure progression among patients with COVID-19 is critical to identification of therapeutic targets.

Methods

We conducted a prospective observational study of circulating levels of CD11b + [NET + N] immunotyped for dual endothelin-1/signal peptide receptor (DEspR ±) expression by quantitative immunofluorescence-cytology and causal mediation analysis. In 36 consented adults hospitalized with mod-severe COVID-19, May to September 2020, we measured acute multi-organ failure via SOFA-scores and respiratory failure via SaO2/FiO2 (SF)-ratio at time points t1 (average 5.5 days from ICU/hospital admission) and t2 (the day before ICU-discharge or death), and ICU-free days at day28 (ICUFD). Circulating absolute neutrophil counts (ANC) and [NET + N] subset-specific counts were measured at t1. Spearman correlation and causal mediation analyses were conducted.

Results

Spearman correlation analyses showed correlations of t1-SOFA with t2-SOFA (rho r S  = 0.80) and ICUFD (r S  = -0.76); circulating DEspR + [NET + Ns] with t1-SOFA (r S  = 0.71), t2-SOFA (r S  = 0.62), and ICUFD (r S  = -0.63), and ANC with t1-SOFA (r S  = 0.71), and t2-SOFA (r S  = 0.61).Causal mediation analysis identified DEspR + [NET + Ns] as mediator of 44.1% [95% CI:16.5,110.6] of the causal path between t1-SOFA (exposure) and t2-SOFA (outcome), with 46.9% [15.8,124.6] eliminated when DEspR + [NET + Ns] were theoretically reduced to zero. Concordantly, DEspR + [NET + Ns] mediated 47.1% [22.0,72.3%] of the t1-SOFA to ICUFD causal path, with 51.1% [22.8,80.4%] eliminated if DEspR + [NET + Ns] were reduced to zero. In patients with t1-SOFA > 1, the indirect effect of a hypothetical treatment eliminating DEspR + [NET + Ns] projected a reduction of t2-SOFA by 0.98 [0.29,2.06] points and ICUFD by 3.0 [0.85,7.09] days. In contrast, there was no significant mediation of SF-ratio through DEspR + [NET + Ns], and no significant mediation of SOFA-score through ANC.

Conclusions

Despite equivalent correlations, DEspR + [NET + Ns], but not ANC, mediated progression of multi-organ failure in acute COVID-19, and its hypothetical reduction is projected to improve ICUFD. These translational findings warrant further studies of DEspR + [NET + Ns] as potential patient-stratifier and actionable therapeutic target for multi-organ failure in COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41231-023-00143-x.

Circulating neutrophil extracellular trap (NET)-forming 'rogue' neutrophil subset, immunotype [DEspR+CD11b+], mediate multi-organ failure in COVID-19 - an observational study

Background: Cumulative research show association of neutrophils and neutrophil extracellular traps (NETs) with poor outcomes in severe COVID-19. However, to date, no curative intent therapy has been identified to block neutrophil/NETs-mediated progression of multi-organ dysfunction. Because of emerging neutrophil heterogeneity, the study of subsets of circulating neutrophil-extracellular trap (NET)-forming neutrophils [NET+Ns] as mediators of multi-organ failure progression among patients with COVID-19 is critical to identification of therapeutic targets. Methods: We conducted a prospective observational study of circulating levels of CD11b+[NET+N] immunotyped for dual endothelin-1/signal peptide receptor, (DEspR±) expression by quantitative immunofluorescence-cytology and causal mediation analysis. In 36 consented adults hospitalized with mod-severe COVID-19, May to September 2020, we measured acute multi-organ failure via SOFA-scores and respiratory failure via SaO2/FiO2 (SF)ratio at time points t1 (average 5.5 days from ICU/hospital admission) and t2 (the day before ICU-discharge or death), and ICU-free days at day28 (ICUFD). Circulating absolute neutrophil counts (ANC) and [NET+N] subset-specific counts were measured at t1. Spearman correlation and causal mediation analyses were conducted. Results: Spearman correlation analyses showed correlations of t1-SOFA with t2-SOFA ( rho r _S =0.80) and ICUFD ( r _S =-0.76); circulating DEspR+[NET+Ns] with t1-SOFA ( r _S = 0.71), t2-SOFA ( r _S =0.62), and ICUFD ( r _S =-0.63), and ANC with t1-SOFA ( r _S =0.71), and t2-SOFA ( r _S =0.61). Causal mediation analysis identified DEspR+[NET+Ns] as mediator of 44.1% [95% CI:16.5,110.6] of the causal path between t1-SOFA (exposure) and t2-SOFA (outcome), with 46.9% [15.8,124.6] eliminated when DEspR+[NET+Ns] were theoretically reduced to zero. Concordantly, DEspR+[NET+Ns] mediated 47.1% [22.0,72.3%] of the t1-SOFA to ICUFD causal path, with 51.1% [22.8,80.4%] eliminated if DEspR+[NET+Ns] were reduced to zero. In patients with t1-SOFA >1, the indirect effect of a hypothetical treatment eliminating DEspR+[NET+Ns] projected a reduction of t2-SOFA by 0.98 [0.29,2.06] points and ICUFD by 3.0 [0.85,7.09] days. In contrast, there was no significant mediation of SF-ratio through DEspR+[NET+Ns], and no significant mediation of SOFA-score through ANC. Conclusions: Despite equivalent correlations, DEspR+[NET+Ns], but not ANC, mediated progression of multi-organ failure in acute COVID-19, and its hypothetical reduction is projected to improve ICUFD. These translational findings warrant further studies of DEspR+[NET+Ns] as potential patient-stratifier and actionable therapeutic target for multi-organ failure in COVID-19.

COVID-19: A Comprehensive Review on Cardiovascular Alterations, Immunity, and Therapeutics in Older Adults

Here, we present a review focusing on three relevant issues related to COVID-19 and its impact in older adults (60 years and older). SARS-CoV-2 infection starts in the respiratory system, but the development of systemic diseases accompanied by severe clinical manifestations has also been reported, with cardiovascular and immune system dysfunction being the major ones. Additionally, the presence of comorbidities and aging represent major risk factors for the severity and poor prognosis of the disease. Since aging-associated decline has been largely related to immune and cardiovascular alterations, we sought to investigate the consequences and the underlying mechanisms of these pathologies to understand the severity of the illness in this population. Understanding the effects of COVID-19 on both systems should translate into comprehensive and improved medical care for elderly COVID-19 patients, preventing cardiovascular as well as immunological alterations in this population. Approved therapies that contribute to the improvement of symptoms and a reduction in mortality, as well as new therapies in development, constitute an approach to managing these disorders. Among them, we describe antivirals, cytokine antagonists, cytokine signaling pathway inhibitors, and vaccines.

COVID-19 immunopathology: From acute diseases to chronic sequelae

The clinical manifestation of coronavirus disease 2019 (COVID-19) mainly targets the lung as a primary affected organ, which is also a critical site of immune cell activation by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, recent reports also suggest the involvement of extrapulmonary tissues in COVID-19 pathology. The interplay of both innate and adaptive immune responses is key to COVID-19 management. As a result, a robust innate immune response provides the first line of defense, concomitantly, adaptive immunity neutralizes the infection and builds memory for long-term protection. However, dysregulated immunity, both innate and adaptive, can skew towards immunopathology both in acute and chronic cases. Here we have summarized some of the recent findings that provide critical insight into the immunopathology caused by SARS-CoV-2, in acute and post-acute cases. Finally, we further discuss some of the immunomodulatory drugs in preclinical and clinical trials for dampening the immunopathology caused by COVID-19.

Investigation of Neutrophil Extracellular Traps as Potential Mediators in the Pathogenesis of Non-Acute Subdural Hematomas: A Pilot Study

Non-acute subdural hematomas (NASHs) are a cause of significant morbidity and mortality, particularly with recurrences. Although recurrence is believed to involve a disordered neuroinflammatory cascade involving vascular endothelial growth factor (VEGF), this pathway has yet to be completely elucidated. Neutrophil extracellular traps (NETs) are key factors that promote inflammation/apoptosis and can be induced by VEGF. We investigated whether NETs are present in NASH membranes, quantified NET concentrations, and examined whether NET and VEGF levels are correlated in NASHs. Samples from patients undergoing NASH evacuation were collected during surgery and postoperatively at 24 and 48 h. Fluid samples and NASH membranes were analyzed for levels of VEGF, NETs, and platelet activation. NASH samples contained numerous neutrophils positive for NET formation. Myeloperoxidase-DNA complexes (a marker of NETs) remained elevated 48 h postoperatively (1.06 ± 0.22 day 0, 0.72 ± 0.23 day 1, and 0.83 ± 0.33 day 2). VEGF was also elevated in NASHs (7.08 ± 0.98 ng/mL day 0, 3.40 ± 0.68 ng/mL day 1, and 6.05 ± 1.8 ng/mL day 2). VEGF levels were significantly correlated with myeloperoxidase-DNA levels. These results show that NETs are increasing in NASH, a finding that was previously unknown. The strong correlation between NET and VEGF levels indicates that VEGF may be an important mediator of NET-related inflammation in NASH.

Expression of DEspR in acute intracerebral hemorrhage

OBJECTIVES

Neuroinflammation and secondary injury play a central role in the pathophysiology of intracerebral hemorrhage. The dual endothelin-1/VEGFsignal-peptide receptor (DEspR) has been reported to mediate the inflammatory response after acute brain injury in a rodent model. We performed a pilot study to assess the expression of DEspR on circulating leukocytes in patients who presented with spontaneous intracerebral hemorrhage (ICH).

MATERIALS AND METHODS

We performed a prospective observational study of patients presenting to two academic medical centers with ICH. Normal healthy volunteers (NHV) were also recruited for sample analysis. Whole blood was obtained, and flow cytometry was performed to examine DEspR expression on neutrophils, monocytes, and lymphocytes.

RESULTS

A total of 19 patients were included in analysis. Median ICH volume was 39 cm3 [IQR 19 cm3, 73 cm3] and median ICH score was 2 [IQR 2, 3]. DEspR expression was more abundant on neutrophils (median 2.4% [IQR 0.5%, 5.8%], p = 0.0064) and monocytes (median 4.4% [IQR 1.7%, 15.8%], p = 0.003) relative to lymphocytes (median 0.9% [IQR 0.2%, 3.3%]). ICH patients had higher DEspR expression in all leukocytes relative to NHV (p < 0.05 for all). Among ICH patients, those with a medical history of hypertension showed higher DEspR expression on neutrophils and monocytes (p = 0.018) compared to those without hypertension.

CONCLUSIONS

In this pilot study, DEspR is expressed on circulating neutrophils and monocytes in humans after ICH, with higher levels of expression in those with hypertension. Future work in larger cohorts should examine the relationship of DEspR expression with neuroinflammatory endpoints and long-term outcome.

Plasma biomarkers for systemic inflammation in COVID-19 survivors

BACKGROUND

While the majority of COVID-19 patients fully recover from the infection and become asymptomatic, a significant proportion of COVID-19 survivors experience a broad spectrum of symptoms lasting weeks to months post-infection, a phenomenon termed "post-acute sequelae of COVID-19 (PASC)." The aim of this study is to determine whether inflammatory proteins are dysregulated and can serve as potential biomarkers for systemic inflammation in COVID-19 survivors.

METHODS

We determined the levels of inflammatory proteins in plasma from 22 coronavirus disease 2019 (COVID-19) long haulers (COV-LH), 22 COVID-19 asymptomatic survivors (COV-AS), and 22 healthy subjects (HS) using an Olink proteomics assay and assessed the results by a beads-based multiplex immunoassay.

RESULTS

Compared to HS, we found that COVID-19 survivors still exhibited systemic inflammation, as evidenced by significant changes in the levels of multiple inflammatory proteins in plasma from both COV-LH and COV-AS. CXCL10 was the only protein that significantly upregulated in COV-LH compared with COV-AS and HS.

CONCLUSIONS

Our results indicate that several inflammatory proteins remain aberrantly dysregulated in COVID-19 survivors and CXCL10 might serve as a potential biomarker to typify COV-LH. Further characterization of these signature inflammatory molecules might improve the understanding of the long-term impacts of COVID-19 and provide new targets for the diagnosis and treatment of COVID-19 survivors with PASC.

Cell deaths: Involvement in the pathogenesis and intervention therapy of COVID-19

The current pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has dramatically influenced various aspects of the world. It is urgent to thoroughly study pathology and underlying mechanisms for developing effective strategies to prevent and treat this threatening disease. It is universally acknowledged that cell death and cell autophagy are essential and crucial to maintaining host homeostasis and participating in disease pathogenesis. At present, more than twenty different types of cell death have been discovered, some parts of which have been fully understood, whereas some of which need more investigation. Increasing studies have indicated that cell death and cell autophagy caused by coronavirus might play an important role in virus infection and pathogenicity. However, the knowledge of the interactions and related mechanisms of SARS-CoV-2 between cell death and cell autophagy lacks systematic elucidation. Therefore, in this review, we comprehensively delineate how SARS-CoV-2 manipulates diverse cell death (including apoptosis, necroptosis, pyroptosis, ferroptosis, and NETosis) and cell autophagy for itself benefits, which is simultaneously involved in the occurrence and progression of COVID-19, aiming to provide a reasonable basis for the existing interventions and further development of novel therapies.

Post-acute sequelae of COVID-19: A metabolic perspective

The SARS-CoV-2 pandemic continues to rage around the world. At the same time, despite strong public health measures and high vaccination rates in some countries, a post-COVID-19 syndrome has emerged which lacks a clear definition, prevalence, or etiology. However, fatigue, dyspnea, brain fog, and lack of smell and/or taste are often characteristic of patients with this syndrome. These are evident more than a month after infection, and are labeled as Post-Acute Sequelae of CoV-2 (PASC) or commonly referred to as long-COVID. Metabolic dysfunction (i.e., obesity, insulin resistance, and diabetes mellitus) is a predisposing risk factor for severe acute COVID-19, and there is emerging evidence that this factor plus a chronic inflammatory state may predispose to PASC. In this article, we explore the potential pathogenic metabolic mechanisms that could underly both severe acute COVID-19 and PASC, and then consider how these might be targeted for future therapeutic approaches.

Significance of Immune Status of SARS-CoV-2 Infected Patients in Determining the Efficacy of Therapeutic Interventions

Coronavirus disease 2019 (COVID-19) is now being investigated for its distinctive patterns in the course of disease development which can be indicated with miscellaneous immune responses in infected individuals. Besides this series of investigations on the pathophysiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), significant fundamental immunological and physiological processes are indispensable to address clinical markers of COVID-19 disease and essential to identify or design effective therapeutics. Recent developments in the literature suggest that deficiency of type I interferon (IFN) in serum samples can be used to represent a severe progression of COVID-19 disease and can be used as the basis to develop combined immunotherapeutic strategies. Precise control over inflammatory response is a significant aspect of targeting viral infections. This account presents a brief review of the pathophysiological characteristics of the SARS-CoV-2 virus and the understanding of the immune status of infected patients. We further discuss the immune system’s interaction with the SARS-CoV-2 virus and their subsequent involvement of dysfunctional immune responses during the progression of the disease. Finally, we highlight some of the implications of the different approaches applicable in developing promising therapeutic interventions that redirect immunoregulation and viral infection.

Neutrophil subsets and their differential roles in viral respiratory diseases

Neutrophils play significant roles in immune homeostasis and as neutralizers of microbial infections. Recent evidence further suggests heterogeneity of neutrophil developmental and activation states that exert specialized effector functions during inflammatory disease conditions. Neutrophils can play multiple roles during viral infections, secreting inflammatory mediators and cytokines that contribute significantly to host defense and pathogenicity. However, their roles in viral immunity are not well understood. In this review, we present an overview of neutrophil heterogeneity and its impact on the course and severity of viral respiratory infectious diseases. We focus on the evidence demonstrating the crucial roles neutrophils play in the immune response toward respiratory infections, using influenza as a model. We further extend the understanding of neutrophil function with the studies pertaining to COVID‐19 disease and its neutrophil‐associated pathologies. Finally, we discuss the relevance of these results for future therapeutic options through targeting and regulating neutrophil‐specific responses.