Neutrophils in COVID-19: recent insights and advances

Ribociclib leverages phosphodiesterase 4 inhibition in the treatment of neutrophilic inflammation and acute respiratory distress syndrome

INTRODUCTION

Overwhelming neutrophil activation and oxidative stress significantly contribute to acute respiratory distress syndrome (ARDS) pathogenesis. However, the potential of repurposing ribociclib, a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor used clinically in cancer treatment, for treating neutrophilic ARDS remains uncertain. This study illustrated the ability and underlying mechanism of ribociclib for treating ARDS and neutrophilic inflammation.

METHODS

Primary human neutrophils were used to determine the therapeutic effects of ribociclib on respiratory bursts, chemotactic responses, and inflammatory signaling. In vitro and silico analyses were performed to determine the underlying molecular mechanisms. The potential of ribociclib repurposing was evaluated using an in vivo ARDS model in lipopolysaccharide (LPS)-primed mice.

RESULTS

We found that treatment using ribociclib markedly limited overabundant oxidative stress (reactive oxygen species [ROS]) production and chemotactic responses (integrin levels and adhesion) in activated human neutrophils. Ribociclib was also shown to act as a selective inhibitor of phosphodiesterase 4 (PDE4), thereby promoting the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway, leading to the inhibition of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) phosphorylation, and calcium influx. Notably, prophylactic administration and post-treatment with ribociclib ameliorated neutrophil infiltration, lung inflammation, accumulation of oxidative stress, pulmonary destruction, and mortality in mice with LPS-induced ARDS.

CONCLUSION

We demonstrated for the first time that ribociclib serves as a novel PDE4 inhibitor for treating neutrophilic inflammation and ARDS. The repurposing ribociclib and targeting neutrophilic PDE4 offer a potential off-label alternative for treating lung lesions and other inflammatory conditions.

A Dual Pharmacological Strategy against COVID-19: The Therapeutic Potential of Metformin and Atorvastatin

Metformin (MET) and atorvastatin (ATO) are promising treatments for COVID-19. This review explores the potential of MET and ATO, commonly prescribed for diabetes and dyslipidemia, respectively, as versatile medicines against SARS-CoV-2. Due to their immunomodulatory and antiviral capabilities, as well as their cost-effectiveness and ubiquitous availability, they are highly suitable options for treating the virus. MET's effect extends beyond managing blood sugar, impacting pathways that can potentially decrease the severity and fatality rates linked with COVID-19. It can partially block mitochondrial complex I and stimulate AMPK, which indicates that it can be used more widely in managing viral infections. ATO, however, impacts cholesterol metabolism, a crucial element of the viral replicative cycle, and demonstrates anti-inflammatory characteristics that could modulate intense immune reactions in individuals with COVID-19. Retrospective investigations and clinical trials show decreased hospitalizations, severity, and mortality rates in patients receiving these medications. Nevertheless, the journey from observing something to applying it in a therapeutic setting is intricate, and the inherent diversity of the data necessitates carefully executed, forward-looking clinical trials. This review highlights the requirement for efficacious, easily obtainable, and secure COVID-19 therapeutics and identifies MET and ATO as promising treatments in this worldwide health emergency.

Evaluation of molecular mechanisms of riboflavin anti-COVID-19 action reveals anti-inflammatory efficacy rather than antiviral activity

BACKGROUND

Riboflavin (vitamin B2) is one of the most important water-soluble vitamins and a coenzyme involved in many biochemical processes. It has previously been shown that adjuvant therapy with flavin mononucleotide (a water-soluble form of riboflavin) correlates with normalization of clinically relevant immune markers in patients with COVID-19, but the mechanism of this effect remains unclear. Here, the antiviral and anti-inflammatory effects of riboflavin were investigated to elucidate the molecular mechanisms underlying the riboflavin-induced effects.

METHODS

Riboflavin was evaluated for recombinant SARS-CoV-2 PLpro inhibition in an enzyme kinetic assay and for direct inhibition of SARS-CoV-2 replication in Vero E6 cells, as well as for anti-inflammatory activity in polysaccharide-induced inflammation models, including endothelial cells in vitro and acute lung inflammation in vivo.

RESULTS

For the first time, the ability of riboflavin at high concentrations (above 50 μM) to inhibit SARS-CoV-2 PLpro protease in vitro was demonstrated; however, no inhibition of viral replication in Vero E6 cells in vitro was found. At the same time, riboflavin exerted a pronounced anti-inflammatory effect in the polysaccharide-induced inflammation model, both in vitro, preventing polysaccharide-induced cell death, and in vivo, reducing inflammatory markers (IL-1β, IL-6, and TNF-α) and normalizing lung histology.

CONCLUSIONS

It is concluded that riboflavin reveals anti-inflammatory rather than antiviral activity for SARS-CoV-2 infection.

GENERAL SIGNIFICANCE

Riboflavin could be suggested as a promising compound for the therapy of inflammatory diseases of broad origin.

Do Neutrophil-Lymphocyte Ratio and Platelet-Lymphocyte Ratio Need to Be Stratified for Age and Comorbidities in COVID-19 Disease? A Subgroup Analysis of Two Distinct Cohorts over Disease Course

Several studies described neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) as markers of COVID-19 severity. In a recently published study, age and frailty affected NLR and PLR more than disease severity. The study compared two distinct cohorts. The first comprised older frailer patients positive for SARS-CoV-2, with mild or asymptomatic disease, admitted to designated COVID-19 departments in a large geriatric medical center (GMC). The second cohort comprised COVID-19 patients admitted to a large general hospital (GH) for symptomatic disease. This was a follow-up study comparing a subgroup of patients who had NLR and PLR values measured a week after admission. Only 100 of 177 patients in the original GMC cohort had a second NLR test compared to almost all (287 of 289) patients in the general hospital (GH) cohort. The subgroup baseline characteristics did not change significantly from that of the original cohort. Disease symptoms were more prevalent in the GH cohort. In the GMC group, the median second NLR rose from 3.9 to 4.6, while in the GH cohort, the NLR value dropped from 3.5 to 2.8, enhancing the NLR differences between the groups. Smaller changes were observed in the second PLR. These results strengthen the prior results that age and frailty seem to have a stronger impact on NLR and PLR than disease severity.

Neutrophil extracellular traps and their implications in airway inflammatory diseases

Neutrophil extracellular traps (NETs) are essential for immune defense and have been increasingly recognized for their role in infection and inflammation. In the context of airway inflammatory diseases, there is growing evidence suggesting the involvement and significance of NETs. This review aims to provide an overview of the formation mechanisms and components of NETs and their impact on various airway inflammatory diseases, including acute lung injury/ARDS, asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis. By understanding the role of NETs in airway inflammation, we can gain valuable insights into the underlying pathogenesis of these diseases and identify potential targets for future therapeutic strategies that either target NETs formation or modulate their harmful effects. Further research is warranted to elucidate the complex interactions between NETs and airway inflammation and to develop targeted therapies that can effectively mitigate their detrimental effects while preserving their beneficial functions in host defense.

The neutrophil-lymphocyte ratio predicts all-cause and cardiovascular mortality among U.S. adults with rheumatoid arthritis: results from NHANES 1999-2020

Background

The neutrophil-to-lymphocyte ratio (NLR) is recognized as a biomarker for systemic inflammation and immune activation. However, its connection with the mortality risk in individuals with rheumatoid arthritis (RA) is not well understood. This study aimed to investigate the association between NLR and all-cause and cardiovascular mortality risk in U.S. adults with RA.

Methods

Data were gathered from the National Health and Nutrition Examination Survey (NHANES) cycles spanning 1999 to March 2020. We included adults aged ≥20 years. The NLR was computed by dividing the neutrophil count by the lymphocyte count from complete blood counts. The maximally selected rank statistics method helped identify the optimal NLR cutoff value associated with significant survival outcomes. Multivariable logistic regression models were performed to investigate the relationship between the NLR and the all-cause and cardiovascular mortality of RA. Restricted cubic spline (RCS) analyses were utilized to detect whether there were linear or non-linear relationships between NLR and mortality.

Results

In this study, 2002 adults with RA were included, with 339 having a higher NLR (≥3.28) and 1663 having a lower NLR (<3.28). During a median follow-up of 84 months, 79 RA individuals died. Participants with higher NLR had a 2-fold increased risk of all-cause (HR = 2.02, 95% CI: 1.53-2.66) and cardiovascular mortality (HR = 2.48, 95% CI: 1.34-4.57) versus lower NLR, after adjusting for demographics, socioeconomic status, and lifestyle factors. Kaplan-Meier analysis revealed that the survival rate for the higher NLR group was significantly lower than the lower NLR group, in terms of both all-cause and cardiovascular mortality (both P<0.0001). The RCS curve demonstrated a positive linear association between the NLR and all-cause and cardiovascular mortality.

Conclusion

A higher NLR was independently predictive of elevated long-term mortality risk in U.S. adults with RA. The NLR may serve as an inexpensive, widely available prognostic marker in RA.

A hub gene signature as a therapeutic target and biomarker for sepsis and geriatric sepsis-induced ARDS concomitant with COVID-19 infection

Background

COVID-19 and sepsis represent formidable public health challenges, characterized by incompletely elucidated molecular mechanisms. Elucidating the interplay between COVID-19 and sepsis, particularly in geriatric patients suffering from sepsis-induced acute respiratory distress syndrome (ARDS), is of paramount importance for identifying potential therapeutic interventions to mitigate hospitalization and mortality risks.

Methods

We employed bioinformatics and systems biology approaches to identify hub genes, shared pathways, molecular biomarkers, and candidate therapeutics for managing sepsis and sepsis-induced ARDS in the context of COVID-19 infection, as well as co-existing or sequentially occurring infections. We corroborated these hub genes utilizing murine sepsis-ARDS models and blood samples derived from geriatric patients afflicted by sepsis-induced ARDS.

Results

Our investigation revealed 189 differentially expressed genes (DEGs) shared among COVID-19 and sepsis datasets. We constructed a protein-protein interaction network, unearthing pivotal hub genes and modules. Notably, nine hub genes displayed significant alterations and correlations with critical inflammatory mediators of pulmonary injury in murine septic lungs. Simultaneously, 12 displayed significant changes and correlations with a neutrophil-recruiting chemokine in geriatric patients with sepsis-induced ARDS. Of these, six hub genes (CD247, CD2, CD40LG, KLRB1, LCN2, RETN) showed significant alterations across COVID-19, sepsis, and geriatric sepsis-induced ARDS. Our single-cell RNA sequencing analysis of hub genes across diverse immune cell types furnished insights into disease pathogenesis. Functional analysis underscored the interconnection between sepsis/sepsis-ARDS and COVID-19, enabling us to pinpoint potential therapeutic targets, transcription factor-gene interactions, DEG-microRNA co-regulatory networks, and prospective drug and chemical compound interactions involving hub genes.

Conclusion

Our investigation offers potential therapeutic targets/biomarkers, sheds light on the immune response in geriatric patients with sepsis-induced ARDS, emphasizes the association between sepsis/sepsis-ARDS and COVID-19, and proposes prospective alternative pathways for targeted therapeutic interventions.