Impaired neutrophil extracellular trap formation: a novel defect in the innate immune system of aged individuals

Immune aging and infectious diseases

ABSTRACT

The rise in global life expectancy has led to an increase in the older population, presenting significant challenges in managing infectious diseases. Aging affects the innate and adaptive immune systems, resulting in chronic low-grade inflammation (inflammaging) and immune function decline (immunosenescence). These changes would impair defense mechanisms, increase susceptibility to infections and reduce vaccine efficacy in older adults. Cellular senescence exacerbates these issues by releasing pro-inflammatory factors, further perpetuating chronic inflammation. Moreover, comorbidities, such as cardiovascular disease and diabetes, which are common in older adults, amplify immune dysfunction, while immunosuppressive medications further complicate responses to infections. This review explores the molecular and cellular mechanisms driving inflammaging and immunosenescence, focusing on genomic instability, telomere attrition, and mitochondrial dysfunction. Additionally, we discussed how aging-associated immune alterations influence responses to bacterial, viral, and parasitic infections and evaluated emerging antiaging strategies, aimed at mitigating these effects to improve health outcomes in the aging population.

Hospitalised older adults with community-acquired pneumonia and sepsis have dysregulated neutrophil function but preserved glycolysis

OBJECTIVE

Community-acquired pneumonia (CAP) is a leading cause of hospitalisation in older adults and is associated with a high likelihood of adverse outcomes. Given the ageing population and lack of therapeutic advances in CAP, new strategies to manage the burden of this disease are needed. Neutrophil dysfunction has been widely demonstrated in CAP and is associated with poor outcomes. We hypothesised that impaired glycolytic metabolism was driving neutrophil dysfunction in older adults with CAP.

METHODS

To investigate the mechanism underlying neutrophil dysfunction in CAP, we recruited older adults with CAP and sepsis, age-matched controls and healthy young adults to assess neutrophil function and glycolytic metabolism in peripheral blood neutrophils.

RESULTS

We demonstrate that neutrophils from older donors with CAP display a broad range of functional defects, including inaccurate migration to interleukin 8, impaired respiratory burst in response to phorbol 12-myristate 13-acetate and increased spontaneous degranulation compared with age-matched controls. Glycolysis (assessed by extracellular flux and RNA-sequencing) was not significantly altered between age-matched groups; however, basal rates of neutrophil glycolysis were significantly higher in patients with CAP and older adult controls compared with healthy young adults, and stimulated glycolysis was significantly higher in young adults compared with older adults with and without CAP.

CONCLUSIONS

Our findings suggest that neutrophil dysfunction in older adults with CAP may be implicated in poor outcomes, irrespective of glycolytic metabolism.

Increased cell-free DNA in CSF and serum of hip fracture patients with delirium

Delirium is a neuropsychiatric syndrome commonly presenting during acute illness. The pathophysiology of delirium is unknown, but neuroinflammation is suggested to play a role. In this cross-sectional study, we aimed to investigate whether cell-free DNA and markers of neutrophil extracellular traps in serum and CSF were associated with delirium and neuronal damage, assessed by neurofilament light chain. Hip fracture patients (n = 491) with a median (25, 75 percentiles) age of 83 (74, 88) years and 69% females were enrolled at Oslo University Hospital, Diakonhjemmet Hospital, Akershus University Hospital and Bærum Hospital. Delirium was assessed daily, pre- and postoperatively. Cognitively healthy adults (n = 32) with a median (25, 75 percentiles) age of 75 (70, 77) years and 53% females were included as controls. Cell-free DNA was measured by using the fluorescent nucleic acid stain Quant-iT PicoGreen® in serum and CSF. Myeloperoxidase-DNA and citrullinated histone H3 were analysed by enzyme-linked immunosorbent assay in serum. Hip fracture patients have significantly higher levels of cell-free DNA and neutrophil extracellular traps in blood than cognitively healthy controls. In hip fracture patients without dementia, cell-free DNA in CSF and serum was significantly higher in patients with (n = 68) versus without (n = 221) delirium after adjusting for age and sex (70 (59, 84) versus 62 (53, 77) ng/ml, P = 0.037) and 601 (504, 684) versus 508 (458, 572) ng/ml, P = 0.007, respectively). In the total hip fracture cohort, CSF levels of cell-free DNA and neurofilament light chain were significantly correlated after adjusting for age and sex (r = 0.441, P < 0.001). The correlation was stronger in those with delirium (r = 0.468, P < 0.001) and strongest in delirious patients without dementia (r = 0.765, P = 0.045). In delirious patients without dementia, significantly higher levels of cell-free DNA in CSF and serum were shown. The association between cell-free DNA and neurofilament light chain suggest simultaneous release of cell-free DNA and neuronal damage during delirium.

Elevation of circulating neutrophil extracellular traps in endometrial cancer: Poor prognostic value of cell-free double-stranded DNA

OBJECTIVE

Neutrophils produce neutrophil extracellular traps (NETs) by releasing nuclear contents into the extracellular environment. NETs are associated with systemic inflammation and cancer development and progression. We aimed to investigate whether NET markers are associated with the prognosis of endometrial cancer.

METHODS

Circulating levels of three NET markers (histone-DNA complex, cell-free double-stranded DNA (dsDNA), and neutrophil elastase) were measured in 98 patients with endometrial cancer who underwent surgery as primary treatment between January 2015 and June 2018 and 45 healthy women. Area under the receiver operating characteristic curve (AUC) analyses were conducted to investigate the diagnostic and prognostic utility of the markers for endometrial cancer.

RESULTS

Patients with endometrial cancer showed significantly higher levels of the three NET markers than those in healthy controls. In discriminating endometrial cancer patients from healthy controls, the three NET markers showed AUC values in the following order: cell-free dsDNA (0.832; 95 % CI, 0.760-0.889), histone-DNA complex (0.740; 95 % CI, 0.660-0.809), and neutrophil elastase (0.689; 95 % CI, 0.607-0.764), comparable to those of CA-125 (0.741; 95 % CI, 0.659-0.813). Multivariate analysis adjusting for FIGO stage, histology, and lymphovascular space invasion, and lymph node involvement revealed that cell-free dsDNA level (cutoff: 95.2 ng/mL) was an independent prognostic marker for poor progression-free (adjusted HR, 2.75; 95 % CI, 1.096.92; P = 0.032) and overall survival (adjusted HR, 11.51; 95 % CI, 2.0664.22; P = 0.005) for patients with endometrial cancer.

CONCLUSION

High levels of circulating NET markers were observed in patients with endometrial cancer. Cell-free dsDNA levels may play a role as prognostic markers for endometrial cancer.

The Aging Immune System: A Critical Attack on Ischemic Stroke

Ischemic stroke caused by cerebrovascular embolism is an age-related disease with high rates of disability and mortality. Although the mechanisms of immune and inflammatory development after stroke have been of great interest, most studies have neglected the critical and unavoidable factor of age. As the global aging trend intensifies, the number of stroke patients is constantly increasing, emphasizing the urgency of finding effective measures to address the needs of elderly stroke patients. The concept of "immunosenescence" appears to explain the worse stroke outcomes in older individuals. Immune remodeling due to aging involves dynamic changes at all levels of the immune system, and the overall consequences of central (brain-resident) and peripheral (non-brain-resident) immune cells in stroke vary according to the age of the individual. Lastly, the review outlines recent strategies aimed at immunosenescence to improve stroke prognosis.

Neutrophil and neutrophil extracellular trap involvement in neutrophilic asthma: A review

Asthma is a highly prevalent chronic inflammatory disease characterized by variable airflow obstruction and airway hyperresponsiveness. Neutrophilic asthma (NA) is classified as "type 2 low" asthma, defined as 65% or more neutrophils in the total cell count. There is no clear consensus on the pathogenesis of NA, and the accumulation of neutrophils and release of neutrophil extracellular traps (NETs) may be responsible for its development. A NET is a large extracellular meshwork comprising cell membrane and granule proteins. It is a powerful antimicrobial defence system that traps, neutralizes, and kills bacteria, fungi, viruses, and parasites and prevents the spread of microorganisms. However, dysregulation of NETs may lead to chronic airway inflammation, is associated with worsening of asthma, and has been the subject of major research advances in chronic lung diseases in recent years. NA is insensitive to steroids, and there is a need to find effective biomarkers as targets for the treatment of NA to replace steroids. This review analyses the mechanisms of action between asthmatic neutrophil recruitment and NET formation and their impact on NA development. It also discusses their possible therapeutic significance in NA, summarizing the advances made in NA agents and providing strategies for the treatment of NA, provide a theoretical basis for the development of new therapeutic drugs, thereby improving the level of diagnosis and treatment, and promoting the research progress in the field of asthma.

Understanding the Complex Dynamics of Immunosenescence in Multiple Sclerosis: From Pathogenesis to Treatment

Immunosenescence, the gradual deterioration of immune function with age, holds profound implications for our understanding and management of multiple sclerosis (MS), a chronic autoimmune disease affecting the central nervous system. Traditionally diagnosed in young adults, advancements in disease-modifying therapies and increased life expectancy have led to a growing number of older individuals with MS. This demographic shift underscores the need for a deeper investigation into how age-related alterations in immune function shape the course of MS, influencing disease progression, treatment effectiveness, and overall patient outcomes. Age-related immunosenescence involves changes such as shifts in cytokine profiles, the accumulation of senescent immune cells, and compromised immune surveillance, collectively contributing to a state known as "inflammaging". In the context of MS, these immunological changes disturb the intricate balance between inflammatory and regulatory responses, thereby impacting mechanisms of central immune tolerance and peripheral regulation. This paper stands out by combining the most recent advancements in immunosenescence with both pathophysiological and treatment perspectives on multiple sclerosis, offering a cohesive and accessible discussion that bridges theory and practice, while also introducing novel insights into underexplored concepts such as therapy discontinuation and the latest senolytic, neuroprotective, and remyelination therapies. Enhancing our understanding of these complexities will guide tailored approaches to MS management, ultimately improving clinical outcomes for affected individuals.

Thrombosis and Aging: Fibrin Clot Properties and Oxidative Stress

Significance: Aging is a complex process associated with an increased risk of many diseases, including thrombosis. This review summarizes age-related prothrombotic mechanisms in clinical settings of thromboembolism, focusing on the role of fibrin structure and function modified by oxidative stress. Recent Advances: Aging affects blood coagulation and fibrinolysis via multiple mechanisms, including enhanced oxidative stress, with an imbalance in the oxidant/antioxidant mechanisms, leading to loss of function and accumulation of oxidized proteins, including fibrinogen. Age-related prothrombotic alterations are multifactorial involving enhanced platelet activation, endothelial dysfunction, and changes in coagulation factors and inhibitors. Formation of more compact fibrin clot networks displaying impaired susceptibility to fibrinolysis represents a novel mechanism, which might contribute to atherothrombosis and venous thrombosis. Alterations to fibrin clot structure/function are at least in part modulated by post-translational modifications of fibrinogen and other proteins involved in thrombus formation, with a major impact of carbonylation. Fibrin clot properties are also involved in the efficacy and safety of therapy with oral anticoagulants, statins, and/or aspirin. Critical Issues: Since a prothrombotic state is observed in very elderly individuals free of diseases associated with thromboembolism, the actual role of activated blood coagulation in health remains elusive. It is unclear to what extent oxidative modifications of coagulation and fibrinolytic proteins, in particular fibrinogen, contribute to a prothrombotic state in healthy aging. Future Directions: Ongoing studies will show whether novel therapies that may alter oxidative stress and fibrin characteristics are beneficial to prevent atherosclerosis and thromboembolic events associated with aging.

New insights into healthy ageing, inflammageing and frailty using metabolomics

Human ageing is a normal process and does not necessarily result in the development of frailty. A mix of genetic, environmental, dietary, and lifestyle factors can have an impact on ageing, and whether an individual develops frailty. Frailty is defined as the loss of physiological reserve both at the physical and cellular levels, where systemic processes such as oxidative stress and inflammation contribute to physical decline. The newest "omics" technology and systems biology discipline, metabolomics, enables thorough characterisation of small-molecule metabolites in biological systems at a particular time and condition. In a biological system, metabolites-cellular intermediate products of metabolic reactions-reflect the system's final response to genomic, transcriptomic, proteomic, epigenetic, or environmental alterations. As a relatively newer technique to characterise metabolites and biomarkers in ageing and illness, metabolomics has gained popularity and has a wide range of applications. We will give a comprehensive summary of what is currently known about metabolomics in studies of ageing, with a focus on biomarkers for frailty. Metabolites related to amino acids, lipids, carbohydrates, and redox metabolism may function as biomarkers of ageing and/or frailty development, based on data obtained from human studies. However, there is a complexity that underpins biological ageing, due to both genetic and environmental factors that play a role in orchestrating the ageing process. Therefore, there is a critical need to identify pathways that contribute to functional decline in people with frailty.

A novel in vitro cell model of the proteinase/antiproteinase balance observed in alpha-1 antitrypsin deficiency

Background: Alpha-1 antitrypsin deficiency (AATD) is a genetic condition resulting from mutations in the alpha-1 antitrypsin (AAT) protein, a major systemic antiproteinase, resulting in reduced/no release of AAT, disrupting the proteinase/antiproteinase balance. A sustained imbalance can cause structural changes to the lung parenchyma, leading to emphysema. Predicting and assessing human responses to potential therapeutic candidates from preclinical animal studies have been challenging. Our aims were to develop a more physiologically relevant in vitro model of the proteinase/antiproteinase balance and assess whether the data generated could better predict the efficacy of pharmacological candidates to inform decisions on clinical trials, together with expected biomarker responses. Methods: We developed an in vitro model assessing the proteinase/antiproteinase balance by the changes in the fibrinogen cleavage products of neutrophil elastase (NE) and proteinase 3 (PR3). This allowed the assessment of physiological and pharmaceutical neutrophil serine proteinase (NSP) inhibitors to determine the putative threshold at which the maximal effect is achieved. Results: AAT significantly reduced NE and PR3 activity footprints, with the maximal reduction achieved at concentrations above 10 μM. The inhibitor MPH966 alone also significantly reduced NE footprint generation in a concentration-dependent manner, leveling out above 100 nM but had no effect on the PR3 footprint. At levels of AAT consistent with AATD, MPH966 had an additive effect, reducing the NE activity footprint more than either inhibitor alone. Conclusion: Our results support an inhibitor threshold above which the activity footprint generation appears resistant to increasing dosage. Our model can support the testing of inhibitors, confirming activity biomarkers as indicators of likely pharmaceutical efficacy, the assessment of NSP activity in the pathophysiology of emphysema, and the likely function of biological or pharmacological inhibitors in disease management.

Long-term NMN treatment increases lifespan and healthspan in mice in a sex dependent manner

Nicotinamide adenine dinucleotide (NAD) is essential for many enzymatic reactions, including those involved in energy metabolism, DNA repair and the activity of sirtuins, a family of defensive deacylases. During aging, levels of NAD + can decrease by up to 50% in some tissues, the repletion of which provides a range of health benefits in both mice and humans. Whether or not the NAD + precursor nicotinamide mononucleotide (NMN) extends lifespan in mammals is not known. Here we investigate the effect of long-term administration of NMN on the health, cancer burden, frailty and lifespan of male and female mice. Without increasing tumor counts or severity in any tissue, NMN treatment of males and females increased activity, maintained more youthful gene expression patterns, and reduced overall frailty. Reduced frailty with NMN treatment was associated with increases in levels of Anerotruncus colihominis, a gut bacterium associated with lower inflammation in mice and increased longevity in humans. NMN slowed the accumulation of adipose tissue later in life and improved metabolic health in male but not female mice, while in females but not males, NMN increased median lifespan by 8.5%, possible due to sex-specific effects of NMN on NAD + metabolism. Together, these data show that chronic NMN treatment delays frailty, alters the microbiome, improves male metabolic health, and increases female mouse lifespan, without increasing cancer burden. These results highlight the potential of NAD + boosters for treating age-related conditions and the importance of using both sexes for interventional lifespan studies.

Aging and Inflammation

Aging can be conceptualized as the progressive disequilibrium between stochastic damage accumulation and resilience mechanisms that continuously repair that damage, which eventually cause the development of chronic disease, frailty, and death. The immune system is at the forefront of these resilience mechanisms. Indeed, aging is associated with persistent activation of the immune system, witnessed by a high circulating level of inflammatory markers and activation of immune cells in the circulation and in tissue, a condition called "inflammaging." Like aging, inflammaging is associated with increased risk of many age-related pathologies and disabilities, as well as frailty and death. Herein we discuss recent advances in the understanding of the mechanisms leading to inflammaging and the intrinsic dysregulation of the immune function that occurs with aging. We focus on the underlying mechanisms of chronic inflammation, in particular the role of NF-κB and recent studies targeting proinflammatory mediators. We further explore the dysregulation of the immune response with age and immunosenescence as an important mechanistic immune response to acute stressors. We examine the role of the gastrointestinal microbiome, age-related dysbiosis, and the integrated stress response in modulating the inflammatory "response" to damage accumulation and stress. We conclude by focusing on the seminal question of whether reducing inflammation is useful and the results of related clinical trials. In summary, we propose that inflammation may be viewed both as a clinical biomarker of the failure of resilience mechanisms and as a causal factor in the rising burden of disease and disabilities with aging. The fact that inflammation can be reduced through nonpharmacological interventions such as diet and exercise suggests that a life course approach based on education may be a successful strategy to increase the health span with few adverse consequences.

Towards personalised anti-microbial and immune approaches to infections in acute care. Can real-time genomic-informed diagnosis of pathogens, and immune-focused therapies improve outcomes for patients? An observational, experimental study protocol

INTRODUCTION

Infection causes a vast burden of disease, with significant mortality, morbidity and costs to health-care systems. However, identifying the pathogen causative infection can be challenging, resulting in high use of broad-spectrum antibiotics, much of which may be inappropriate. Novel metagenomic methods have potential to rapidly identify pathogens, however their clinical utility for many infections is currently unclear. Outcome from infection is also impacted by the effectiveness of immune responses, which can be impaired by age, co-morbidity and the infection itself. The aims of this study are twofold: To compare diversity of organisms identified and time-to-result using metagenomic methods versus traditional culture -based techniques, to explore the potential clinical role of metagenomic approaches to pathogen identification in a range of infections.To characterise the ex vivo function of immune cells from patients with acute infection, exploring host and pathogen-specific factors which may affect immune function and overall outcomes.

METHODS

This is a prospective observational study of patients with acute infection. Patients with symptoms suggestive of an acute infection will be recruited, and blood and bodily fluid relevant to the site of infection collected (for example, sputum and naso-oropharyngeal swabs for respiratory tract infections, or urine for a suspected urinary tract infection). Metagenomic analysis of samples will be compared to traditional microbiology, alongside the antimicrobials received. Blood and respiratory samples such as bronchoalveolar lavage will be used to isolate immune cells and interrogate immune cell function. Where possible, similar samples will be collected from matched participants without a suspected infection to determine the impact of infection on both microbiome and immune cell function.

Plasma from patients undergoing allogeneic hematopoietic stem cell transplantation promotes NETOSIS in vitro and correlates with inflammatory parameters and clinical severity

Introduction

NETosis, the mechanism by which neutrophils release extracellular traps (NETs), is closely related to inflammation. During the allogeneic hematopoietic stem cell transplantation (allo-HSCT), different stimuli can induce NETs formation. Inflammation and endothelial injury have been associated with acute graft-versus-host disease (aGVHD) and complications after allo-HSCT. We focus on the study of NETosis and its relation with cytokines, hematological and biochemical parameters and clinical outcomes before, during and after allo-HSCT.

Methods

We evaluate the capacity of plasma samples from allo-HSCT patients to induce NETosis, in a cell culture model. Plasma samples from patients undergoing allo-HSCT had a stronger higher NETs induction capacity (NETsIC) than plasma from healthy donors throughout the transplantation process. An optimal cut-off value by ROC analysis was established to discriminate between patients whose plasma triggered NETosis (NETs+IC group) and those who did not (NETs-IC group).

Results

Prior to conditioning treatment, the capacity of plasma samples to trigger NETosis was significantly correlated with the Endothelial Activation and Stress Index (EASIX) score. At day 5 after transplant, patients with a positive NETsIC had higher interleukin (IL)-6 and C-reactive protein (CRP) levels and also a higher Modified EASIX score (M-EASIX) than patients with a negative NETsIC. EASIX and M-EASIX scores seek to determine inflammation and endothelium damage, therefore it could indicate a heightened immune response and inflammation in the group of patients with a positive NETsIC. Cytokine levels, specifically IL-8 and IL-6, significantly increased after allo-HSCT with peak levels reached on day 10 after graft infusion. Only, IL-10 and IL-6 levels were significantly higher in patients with a positive NETsIC. In our small cohort, higher IL-6 and IL-8 levels were related to early severe complications (before day 15 after transplant).

Discussion

Although early complications were not related to NETosis by itself, NETosis could predict overall non-specific but clinically significant complications during the full patient admission. In summary, NETosis can be directly induced by plasma from allo-HSCT patients and NETsIC was associated with clinical indicators of disease severity, cytokines levels and inflammatory markers.

Circulating myeloid populations have prognostic utility in alcohol-related liver disease

Introduction

Alcohol-related liver disease (ARLD) accounts for over one third of all deaths from liver conditions, and mortality from alcohol-related liver disease has increased nearly five-fold over the last 30 years. Severe alcohol-related hepatitis almost always occurs in patients with a background of chronic liver disease with extensive fibrosis or cirrhosis, can precipitate 'acute on chronic' liver failure and has a high short-term mortality. Patients with alcohol-related liver disease have impaired immune responses, and increased susceptibility to infections, thus prompt diagnosis of infection and careful patient management is required. The identification of early and non-invasive diagnostic and prognostic biomarkers in ARLD remains an unresolved challenge. Easily calculated predictors of infection and mortality are required for use in patients who often exhibit variable symptoms and disease severity and may not always present in a specialized gastroenterology unit.

Methods

We have used a simple haematological analyser to rapidly measure circulating myeloid cell parameters across the ARLD spectrum.

Results and Discussion

We demonstrate for the first time that immature granulocyte (IG) counts correlate with markers of disease severity, and our data suggests that elevated counts are associated with increased short-term mortality and risk of infection. Other myeloid populations such as eosinophils and basophils also show promise. Thus IG count has the potential to serve alongside established markers such as neutrophil: lymphocyte ratio as a simply calculated predictor of mortality and risk of infectious complications in patients with alcohol-related hepatitis. This would allow identification of patients who may require more intensive management.

Senescent cell-derived extracellular vesicles as potential mediators of innate immunosenescence and inflammaging

Ageing is accompanied by a decline in immune function (immunosenescence), increased inflammation (inflammaging), and more senescent cells which together contribute to age-related disease and infection susceptibility. The innate immune system is the front-line defence against infection and cancer and is also involved in the removal of senescent cells, so preventing innate immunosenescence and inflammaging is vital for health in older age. Extracellular vesicles (EVs) modulate many aspects of innate immune function, including chemotaxis, anti-microbial responses, and immune regulation. Senescent cell derived EVs (SEVs) have different cargo to that of non-senescent cell derived EVs, suggesting alterations in EV cargo across the lifespan may influence innate immune function, possibly contributing to immunosenescence and inflammaging. Here we review current understanding of the potential impact of miRNAs, lipids and proteins, found in higher concentrations in SEVs, on innate immune functions and inflammation to consider whether SEVs are potential influencers of innate immunosenescence and inflammaging. Furthermore, senolytics have demonstrated an ability to return plasma EV content closer to that of non-senescent EVs, therefore the potential use of senotherapeutics (senolytics and senostatics) to ameliorate the effects of SEVs on immunosenescence and inflammaging is also considered as a possible strategy for extending health-span in older adults.

Impact of Immunosenescence in Older Kidney Transplant Recipients: Associated Clinical Outcomes and Possible Risk Stratification for Immunosuppression Reduction

The number of older individuals receiving a kidney transplant as replacement therapy has significantly increased in the past decades and this increase is expected to continue. Older patients have a lower rate of acute rejection but an increased incidence of death with a functioning graft. Several factors, including an increased incidence of infections, post-transplant malignancy and cardiovascular comorbidity and mortality, contribute to this increased risk. Notwithstanding, kidney transplantation is still the best form of kidney replacement therapy in all patients with chronic kidney disease, including in older individuals. The best form of immunosuppression and the optimal dose of these medications in older recipients remains a topic of discussion. Pharmacological studies have usually excluded older patients and when included, patients were highly selected and their numbers insignificant to draw a reasonable conclusion. The reduced incidence of acute rejection in older recipients has largely been attributed to immunosenescence. Immunosenescence refers to the aging of the innate and adaptive immunity, accumulating in phenotypic and functional changes. These changes influences the response of the immune system to new challenges. In older individuals, immunosenescence is associated with increased susceptibility to infectious pathogens, a decreased response after vaccinations, increased risk of malignancies and cardiovascular morbidity and mortality. Chronic kidney disease is associated with premature immunosenescent changes, and these are independent of aging. The immunosenescent state is associated with low-grade sterile inflammation termed inflammaging. This chronic low-grade inflammation triggers a compensatory immunosuppressive state to avoid further tissue damage, leaving older individuals with chronic kidney disease in an immune-impaired state before kidney transplantation. Immunosuppression after transplantation may further enhance progression of this immunosenescent state. This review covers the role of immunosenescence in older kidney transplant recipients and it details present knowledge of the changes in chronic kidney disease and after transplantation. The impact of immunosuppression on the progression and complications of an immunosenescent state are discussed, and the future direction of a possible clinical implementation of immunosenescence to individualize/reduce immunosuppression in older recipients is laid out.

Regulatory RNAs in immunosenescence

BACKGROUND

Immunosenescence is a multifactorial stress response to different intrinsic and extrinsic insults that cause immune deterioration and is accompanied by genomic or epigenomic perturbations. It is now widely recognized that genes and proteins contributing in the process of immunosenescence are regulated by various noncoding (nc) RNAs, including microRNAs (miRNAs), long ncRNAs, and circular RNAs.

AIMS

This review article aimed to evaluate the regulatore RNAs roles in the process of immunosenescence.

METHODS

We analyzed publications that were focusing on the different roles of regulatory RNAs on the several aspects of immunosenescence.

RESULTS

In the immunosenescence setting, ncRNAs have been found to play regulatory roles at both transcriptional and post-transcriptional levels. These factors cooperate to regulate the initiation of gene expression programs and sustaining the senescence phenotype and proinflammatory responses.

CONCLUSION

Immunosenescence is a complex process with pivotal alterations in immune function occurring with age. The extensive network that drive immunosenescence-related features are are mainly directed by a variety of regulatory RNAs such as miRNAs, lncRNAs, and circRNAs. Latest findings about regulation of senescence by ncRNAs in the innate and adaptive immune cells as well as their role in the immunosenescence pathways, provide a better understanding of regulatory RNAs function in the process of immunosenescence.

Breast Cancer Immunity: It is TIME for the Next Chapter

Our ability to interrogate the tumor immune microenvironment (TIME) at an ever-increasing granularity has uncovered critical determinants of disease progression. Not only do we now have a better understanding of the immune response in breast cancer, but it is becoming possible to leverage key mechanisms to effectively combat this disease. Almost every component of the immune system plays a role in enabling or inhibiting breast tumor growth. Building on early seminal work showing the involvement of T cells and macrophages in controlling breast cancer progression and metastasis, single-cell genomics and spatial proteomics approaches have recently expanded our view of the TIME. In this article, we provide a detailed description of the immune response against breast cancer and examine its heterogeneity in disease subtypes. We discuss preclinical models that enable dissecting the mechanisms responsible for tumor clearance or immune evasion and draw parallels and distinctions between human disease and murine counterparts. Last, as the cancer immunology field is moving toward the analysis of the TIME at the cellular and spatial levels, we highlight key studies that revealed previously unappreciated complexity in breast cancer using these technologies. Taken together, this article summarizes what is known in breast cancer immunology through the lens of translational research and identifies future directions to improve clinical outcomes.

A turn-on fluorescent probe for detecting and bioimaging of HOCl in inflammatory and liver disease models

Hypochlorous acid (HOCl) is a common reactive oxygen species (ROS) associated with the development of liver, tumor, inflammatory, and other diseases. In this work, the turn-on fluorescent probe named (WZ-HOCl) with a naphthalimide structure was designed and synthesized to detect endogenous HOCl in disease models. WZ-HOCl can achieve a fast response to HOCl with good linearity in the range of 0-45 μM (LOD = 147 nM). The application of WZ-HOCl in bioimaging was investigated by constructing a series of cellular disease models, and the results showed that WZ-HOCl could sensitively detect endogenous HOCl in inflammatory and liver disease models. It can also be used to differentiate between hepatocytes and hepatoma cells. WZ-HOCl will provide new methods and ideas for fluorescent probes in detecting drug-induced liver injury, alcoholic and non-alcoholic steatohepatitis, and some inflammation-related diseases.

Age-related bone diseases: Role of inflammaging

Bone aging is characterized by an imbalance in the physiological and pathological processes of osteogenesis, osteoclastogenesis, adipogenesis, and chondrogenesis, resulting in exacerbated bone loss and the development of age-related bone diseases, including osteoporosis, osteoarthritis, rheumatoid arthritis, and periodontitis. Inflammaging, a novel concept in the field of aging research, pertains to the persistent and gradual escalation of pro-inflammatory reactions during the aging process. This phenomenon is distinguished by its low intensity, systemic nature, absence of symptoms, and potential for management. The mechanisms by which inflammaging contribute to age-related chronic diseases, particularly in the context of age-related bone diseases, remain unclear. The precise manner in which systemic inflammation induces bone aging and consequently contributes to the development of age-related bone diseases has yet to be fully elucidated. This article primarily examines the mechanisms underlying inflammaging and its association with age-related bone diseases, to elucidate the potential mechanisms of inflammaging in age-related bone diseases and offer insights for developing preventive and therapeutic strategies for such conditions.

Neutrophil extracellular traps regulating tumorimmunity in hepatocellular carcinoma

As a component of the innate immune system, there is emerging evidence to suggest that neutrophils may play a critical role in the initiation and progression of hepatocellular carcinoma (HCC). Neutrophil extracellular traps (NETs) are web-like chromatin structures that protrude from the membranes during neutrophil activation. Recent research has shown that NETs, which are at the forefront of the renewed interest in neutrophil studies, are increasingly intertwined with HCC. By exploring the mechanisms of NETs in HCC, we aim to improve our understanding of the role of NETs and gain deeper insights into neutrophil biology. Therefore, this article provides a summary of key findings and discusses the emerging field of NETs in HCC.

Correlations between different protein species of oral rinse MMP-8 and patient-related factors

OBJECTIVES

The aim of this study is to examine correlations between different oral rinse matrix metalloproteinase (MMP)-8 protein species in western blot (WB) analysis, quantitative MMP-8 measurements, and patient-related factors. Elevated activated MMP-8 (aMMP-8) associate with periodontitis and a diagnostic point-of-care technology has been developed based on aMMP-8. In WB, different MMP-8 protein species can be analyzed. Relative abundancy of fragmented 20-25 kDa forms in WB has been associated with and reflects MMP-8 activation and related fragmentation and elevated quantitative aMMP-8 measurements.

MATERIAL AND METHODS

A random sample of 192 participants from a periodontal disease screening study was used for this study. Oral rinse samples for biomarker analyses were collected before clinical periodontal examinations. aMMP-8 immunofluorometric (IFMA) and WB analysis (utilizing the same monoclonal antibody, 8708), polymorphonuclear leukocyte (PMN) elastase activity test and tissue inhibitor of metalloproteinases (TIMP)-1 ELISA levels were performed from the oral rinse samples. Distinct MMP-8 protein species were differentiated in the WB analysis. Principal component (PC) analysis was conducted to explore correlation patterns between the different species. Adjusted correlation analysis between the extracted PCs of WB and aMMP-8 IFMA levels and multilevel regression analysis were conducted to explore if the other periodontal disease-related biomarkers and clinical surrogate measures and patient-related factors are co-variating with the extracted components.

RESULTS

Distinct correlation patterns between the MMP-8 protein species were observed. The first four PCs explained 89% of the whole variance in PC analysis. Statistically significant correlation (p < 0.05) were observed as follows: PC1 positively with 21 kDa (r = .69) and 25 kDa fragments (r = .55) and negatively with 150 kDa complexes (r = -.46). PC2 correlated with 45 (r = .70) and 55 kDa (r = .65) activated forms, PC3 with 70-80 kDa latent proforms (r = .63) and 90-100 kDa complexes (r = .67), and PC4 with 35 kDa fragments (r = .81). There were significant correlations between quantitative (IFMA) aMMP-8 measurements and PC1 (p < 0.001), PC2 (<0.05) and PC3 (<0.05) but not with PC4. In multilevel regression models age, PMN elastase activity, TIMP-1 levels, and a number of 4-5 mm periodontal pockets were associated with PC1, nonsmoking with PC2, age and PMN elastase activity with PC3, and age and smoking with PC4.

CONCLUSIONS

Relative abundancy of fragmented 21-25 kDa protein species was correlated with the quantitative aMMP-8 (IFMA) measurements, which is in line with previous results. Different patient-related factors (smoking, age, proteolytic activity) may modify the formation of different MMP-8 protein species in oral rinse samples and may cause variability in quantitative aMMP-8 measurement.

Energy Regulation in Inflammatory Sarcopenia by the Purinergic System

The purinergic system has a dual role: the maintenance of energy balance and signaling within cells. Adenosine and adenosine triphosphate (ATP) are essential for maintaining these functions. Sarcopenia is characterized by alterations in the control of energy and signaling in favor of catabolic pathways. This review details the association between the purinergic system and muscle and adipose tissue homeostasis, discussing recent findings in the involvement of purinergic receptors in muscle wasting and advances in the use of the purinergic system as a novel therapeutic target in the management of sarcopenia.

Mitochondria-induced formation of neutrophil extracellular traps is enhanced in the elderly via Toll-like receptor 9

Neutrophil extracellular traps are potent antimicrobial weapons; however, their formation during sterile inflammation is detrimental, and the mechanism of induction is still unclear. Since advanced age is the primary clinical risk factor for poor outcomes in inflammatory diseases, we hypothesized that sterile stimuli, represented by mitochondria, would induce neutrophil extracellular trap formation in an age-dependent manner. Therefore, we analyzed induction of neutrophil extracellular traps in patients grouped according to age or immune status and observed that neutrophils from elderly patients responded to the presence of mitochondria with enhanced neutrophil extracellular trap formation. These neutrophil extracellular traps were also found to be more oxidized and exhibited higher resistance to DNase I degradation. Additionally, a higher concentration of residual neutrophil extracellular traps was detected in the plasma of the elderly. This plasma was capable of priming neutrophils through TLR9-mediated signaling, leading to further neutrophil extracellular trap formation, which was successfully inhibited with chloroquine. Finally, in a mouse model of mitochondria-induced acute lung injury, we observed that neutrophils from aged mice displayed impaired chemotactic activity but exhibited a trend of higher neutrophil extracellular trap formation. Thus, we propose that residual neutrophil extracellular traps circulating in the elderly preactivate neutrophils, making them more prone to enhanced neutrophil extracellular trap formation when exposed to mitochondria during sterile inflammation. Further investigation is needed to determine whether this vicious circle could be a suitable therapeutic target.

Immunosenescence and Inflammaging in COVID-19

Despite knowledge gaps in understanding the full spectrum of the hyperinflammatory phase caused by SARS-CoV-2, according to the World Health Organization (WHO), COVID-19 is still the leading cause of death worldwide. Susceptible people to severe COVID-19 are those with underlying medical conditions or those with dysregulated and senescence-associated immune responses. As the immune system undergoes aging in the elderly, such drastic changes predispose them to various diseases and affect their responsiveness to infections, as seen in COVID-19. At-risk groups experience poor prognosis in terms of disease recovery. Changes in the quantity and quality of immune cell function have been described in numerous literature sites. Impaired immune cell function along with age-related metabolic changes can lead to features such as hyperinflammatory response, immunosenescence, and inflammaging in COVID-19. Inflammaging is related to the increased activity of the most inflammatory factors and is the main cause of age-related diseases and tissue failure in the elderly. Since hyperinflammation is a common feature of most severe cases of COVID-19, this pathway, which is not fully understood, leads to immunosenescence and inflammaging in some individuals, especially in the elderly and those with comorbidities. In this review, we shed some light on the age-related abnormalities of innate and adaptive immune cells and how hyperinflammatory immune responses contribute to the inflammaging process, leading to clinical deterioration. Further, we provide insights into immunomodulation-based therapeutic approaches, which are potentially important considerations in vaccine design for elderly populations.

Immunosenescence and multiple sclerosis: inflammaging for prognosis and therapeutic consideration

Aging is associated with a progressive decline of innate and adaptive immune responses, called immunosenescence. This phenomenon links to different multiple sclerosis (MS) disease courses among different age groups. While clinical relapse and active demyelination are mainly related to the altered adaptive immunity, including invasion of T- and B-lymphocytes, impairment of innate immune cell (e.g., microglia, astrocyte) function is the main contributor to disability progression and neurodegeneration. Most patients with MS manifest the relapsing-remitting phenotype at a younger age, while progressive phenotypes are mainly seen in older patients. Current disease-modifying therapies (DMTs) primarily targeting adaptive immunity are less efficacious in older patients, suggesting that immunosenescence plays a role in treatment response. This review summarizes the recent immune mechanistic studies regarding immunosenescence in patients with MS and discusses the clinical implications of these findings.

Immunoaging - the effect of age on serum levels of NET biomarkers in men: a pilot study

OBJECTIVES

The study aimed to evaluate the impact of aging on the formation of neutrophil extracellular traps (NETs). The impaired formation of NETs is the cause of an abnormal innate immune response.

MATERIAL AND METHODS

The study included a total of 45 healthy male subjects of different age groups. Whole blood was collected from the subjects, and the concentration of myeloperoxidase (MPO), the main biocidal protein in NETs, was determined in serum using ELISA. The serum levels of circulating free DNA (cfDNA), which are the structural basis of NETs, were also measured by fluorescence. In addition, the white blood cell count was determined, whole blood smear was evaluated, and the neutrophillymphocyte ratio was calculated. The variations in the levels of NET biomarkers were analyzed in different age groups.

RESULTS

The low levels of MPO (243.70 ng/ml) and cfDNA (6.24 ng/100 μl) in boys indicated neutrophil insufficiency for NETosis in children. A progressive increase in the levels of MPO and cfDNA with age was observed among adolescents (420.91, p = 0.04; 13.55, p = 0.03, respectively), with the highest level noted in the healthy adult group (466.58, p = 0.01; 14.07, p = 0.01, respectively). The levels of the studied parameters were comparable in adolescents and young adults, which proved that the NETosis process was appropriate and suggested the attainment of neutrophil maturity for the release of NETs in adolescence. The levels of MPO and cfDNA were low in older men (225.46, p < 0.01; 5.19, p < 0.01, respectively) indicating impaired NET formation.

CONCLUSIONS

Data on the generation of NETs in different age groups obtained in this study can allow a better understanding of the ontogenesis of the immune system in terms of the course of NETosis, and also indicate the need to support nonspecific responses in children and adults. Further research should be performed to determine the possibility of regulating the NETosis process. Int J Occup Med Environ Health. 2023;36(3):333-48.

Neutrophil extracellular traps and neutrophil-related mediators in human thyroid cancer

Background

Polymorphonuclear neutrophils (PMNs) are the main effector cells in inflammatory responses and play multiple roles in thyroid cancer (TC). PMNs contain and release a plethora of mediators, including granular enzymes [e.g., myeloperoxidase (MPO), pentraxin-3 (PTX3) and matrix metalloproteinase-9 (MMP-9)], and neutrophil extracellular traps (NETs). The aim of this study was to evaluate NETs and neutrophil-derived mediators as possible biomarkers in TC patients.

Methods

20 patients with differentiated thyroid cancer (DTC), 26 patients with dedifferentiated thyroid cancer (De-DTC), 26 patients with multinodular goiter (MNG) and 22 healthy controls (HCs) were recruited. Serum concentrations of free DNA (dsDNA), nucleosomes, citrullinated histone H3 (CitH3) and MPO-DNA complexes were evaluated as NET biomarkers. Neutrophil-related mediators such as MPO, PTX3, MMP-9, CXCL8, and granulocyte-monocyte colony-stimulating factor (GM-CSF) were measured by ELISA.

Results

Serum levels of all four NET biomarkers were increased in DeDTC patients compared to HCs. CitH3 serum levels were selectively increased in both DeDTC and DTC patients compared to HCs and MNG patients. MPO-DNA complexes and nucleosomes were selectively increased only in DeDTC patients compared to HCs and MNG patients. Moreover, MPO-DNA complexes were selectively increased in DeDTC patients compared to DTC patients also. MPO circulating levels were selectively increased in the DeDTC patient subgroup compared to HCs. Circulating levels of PTX3, MMP-9 and GM-CSF were increased in DTC and DeDTC patients compared to HCs. Nucleosomes positively correlated with dsDNA, CitH3, MPO and CXCL8. MPO-DNA complexes positively correlated with dsDNA, CitH3, CXCL8, MPO and nucleosome levels. Moreover, three out of the four NET biomarkers (i.e., dsDNA, nucleosomes and MPO-DNA complexes) were increased in elderly patients compared to young patients and in patients with metastatic disease at diagnosis compared to non metastatic patients. Nucleosomes were higher in males compared to females.

Conclusion

MPO-DNA complexes, nucleosomes and, to some extent, CitH3 levels seem to correlate with malignancy and severity of progressive TC. Moreover, serum concentrations of PMN-related mediators (MPO, PTX3, GM-CSF) were increased in TCs compared to MNG and HCs.

Microbial-Immune Crosstalk in Elderly-Onset Inflammatory Bowel Disease: Unchartered Territory

Elderly-onset inflammatory bowel disease [IBD] patients exhibit a distinct natural history compared to younger IBD patients, with unique disease phenotypes, differential responses to therapy, and increased surgical morbidity and mortality. Despite the foreseeable high demand for personalized medicine and specialized IBD care in the elderly, current paradigms of IBD management fail to capture the required nuances of care for elderly-onset IBD patients. Our review postulates the roles of systemic and mucosal immunosenescence, inflammageing and a dysbiotic microbial ecosystem in the pathophysiology of elderly-onset IBD. Ultimately, a better understanding of elderly-onset IBD can lead to improved patient outcomes and the tailoring of future preventative and treatment strategies.

Detailed Mechanisms Underlying Neutrophil Bactericidal Activity against Streptococcus pneumoniae

Neutrophils are an essential cellular component of innate immunity and control bacterial infections through a combination of intracellular and extracellular killing methods. Although the importance of neutrophils has been established, the exact methods used to handle particular bacterial challenges and the efficiency of bacterial killing remain not well understood. In this study, we addressed how neutrophils eliminate Streptococcus pneumoniae (Spn), a leading cause of community acquired and post-influenza bacterial pneumonia. We analyzed killing methods with variable bacterial:neutrophil concentrations and following priming with PAM3CSK4 (P3CSK), an agonist for Toll-like-receptor 2 (TLR2). Our results show that murine neutrophils display surprisingly weak bactericidal activity against Spn, employing a predominantly extracellular mode of killing at lower concentrations of bacteria, whereas challenges with higher bacterial numbers induce both extracellular and intracellular elimination modes but require TLR2 activation. TLR2 activation increased reactive oxygen species (ROS) and neutrophil extracellular trap (NET) formation in response to Spn. Despite this, supernatants from P3CSK-stimulated neutrophils failed to independently alter bacterial replication. Our study reveals that unstimulated neutrophils are capable of eliminating bacteria only at lower concentrations via extracellular killing methods, whereas TLR2 activation primes neutrophil-mediated killing using both intracellular and extracellular methods under higher bacterial burdens.

Cross-sectional Characterization of SARS-CoV-2 Antibody Levels and Decay Rates Following Infection of Unvaccinated Elderly Individuals

Background

SARS-CoV-2 infections have disproportionally burdened elderly populations with excessive mortality. While several contributing factors exists, questions remain about the quality and duration of humoral antibody-mediated responses resulting from infections in unvaccinated elderly individuals.

Methods

Residual serum/plasma samples were collected from individuals undergoing routine SARS-CoV-2 polymerase chain reaction testing in a community laboratory in Canada. The samples were collected in 2020, before vaccines became available. IgG, IgA, and IgM antibodies against SARS-CoV-2 nucleocapsid, trimeric spike, and its receptor-binding domain were quantified via a high-throughput chemiluminescent enzyme-linked immunosorbent assay. Neutralization efficiency was also quantified through a surrogate high-throughput protein-based neutralization assay.

Results

This study analyzed SARS-CoV-2 antibody levels in a large cross-sectional cohort (N = 739), enriched for elderly individuals (median age, 82 years; 75% >65 years old), where 72% of samples tested positive for SARS-CoV-2 by polymerase chain reaction. The age group ≥90 years had higher levels of antibodies than that <65 years. Neutralization efficiency showed an age-dependent trend, where older persons had higher levels of neutralizing antibodies. Antibodies targeting the nucleocapsid had the fastest decline. IgG antibodies targeting the receptor-binding domain remained stable over time, potentially explaining the lack of neutralization decay observed in this cohort.

Conclusions

Despite older individuals having the highest levels of antibodies postinfection, they are the cohort in which antibody decay was the fastest. Until a better understanding of correlates of protection is acquired, along with the protective role of nonneutralizing antibodies, booster vaccinations remain important in this demographic.

Clinical evidence of human pathogens implicated in Alzheimer's disease pathology and the therapeutic efficacy of antimicrobials: an overview

A wealth of pre-clinical reports and data derived from human subjects and brain autopsies suggest that microbial infections are relevant to Alzheimer's disease (AD). This has inspired the hypothesis that microbial infections increase the risk or even trigger the onset of AD. Multiple models have been developed to explain the increase in pathogenic microbes in AD patients. Although this hypothesis is well accepted in the field, it is not yet clear whether microbial neuroinvasion is a cause of AD or a consequence of the pathological changes experienced by the demented brain. Along the same line, the gut microbiome has also been proposed as a modulator of AD. In this review, we focus on human-based evidence demonstrating the elevated abundance of microbes and microbe-derived molecules in AD hosts as well as their interactions with AD hallmarks. Further, the direct-purpose and potential off-target effects underpinning the efficacy of anti-microbial treatments in AD are also addressed.

Inflammation and aging: signaling pathways and intervention therapies

Aging is characterized by systemic chronic inflammation, which is accompanied by cellular senescence, immunosenescence, organ dysfunction, and age-related diseases. Given the multidimensional complexity of aging, there is an urgent need for a systematic organization of inflammaging through dimensionality reduction. Factors secreted by senescent cells, known as the senescence-associated secretory phenotype (SASP), promote chronic inflammation and can induce senescence in normal cells. At the same time, chronic inflammation accelerates the senescence of immune cells, resulting in weakened immune function and an inability to clear senescent cells and inflammatory factors, which creates a vicious cycle of inflammation and senescence. Persistently elevated inflammation levels in organs such as the bone marrow, liver, and lungs cannot be eliminated in time, leading to organ damage and aging-related diseases. Therefore, inflammation has been recognized as an endogenous factor in aging, and the elimination of inflammation could be a potential strategy for anti-aging. Here we discuss inflammaging at the molecular, cellular, organ, and disease levels, and review current aging models, the implications of cutting-edge single cell technologies, as well as anti-aging strategies. Since preventing and alleviating aging-related diseases and improving the overall quality of life are the ultimate goals of aging research, our review highlights the critical features and potential mechanisms of inflammation and aging, along with the latest developments and future directions in aging research, providing a theoretical foundation for novel and practical anti-aging strategies.

Neutrophils in host defense, healing, and hypersensitivity: Dynamic cells within a dynamic host

Neutrophils are cells of the innate immune system that are extremely abundant in vivo and respond quickly to infection, injury, and inflammation. Their constant circulation throughout the body makes them some of the first responders to infection, and indeed they play a critical role in host defense against bacterial and fungal pathogens. It is now appreciated that neutrophils also play an important role in tissue healing after injury. Their short life cycle, rapid response kinetics, and vast numbers make neutrophils a highly dynamic and potentially extremely influential cell population. It has become clear that they are highly integrated with other cells of the immune system and can thus exert critical effects on the course of an inflammatory response; they can further impact tissue homeostasis and recovery after challenge. In this review, we discuss the fundamentals of neutrophils in host defense and healing; we explore the relationship between neutrophils and the dynamic host environment, including circadian cycles and the microbiome; we survey the field of neutrophils in asthma and allergy; and we consider the question of neutrophil heterogeneity-namely, whether there could be specific subsets of neutrophils that perform different functions in vivo.

SHIP1 is required for the formation of neutrophil extracellular traps in rheumatoid arthritis

Aberrant neutrophil extracellular traps (NETs) are involved in the pathogenesis of rheumatoid arthritis (RA). However, the specific pathway leading to NET formation in RA is poorly understood. Therefore, therapies targeting NETs are not available in RA. In this study, we demonstrated Src homology 2 domain-containing inositol phosphatase-1 (SHIP1) function as a hub to regulate NETosis through SHIP1/ p38 MAPK/TNF-α pathway both in vitro and ex vivo and inhibiting SHIP1 expression ameliorated RA symptoms in vivo. Neutrophils from RA patients showed enhanced NETosis as well as increased SHIP1, p38 mitogen-activated protein kinase (MAPK) family expression and tumor necrosis factor-α (TNF-α) expression. Inhibiting SHIP1 in neutrophils using small molecules counteracted the above-mentioned dysregulations and resulted in decrease in NETosis, p38 expression and TNF-α concentration. Consistent with this, SHIP1 agonist led to upregulated p38MAPK and NET formation. Moreover, inhibiting SHIP1 in vivo led to decreased NETosis and showed beneficial therapeutic effects in Collagen-induced arthritis (CIA) mice. Taken together, these results indicated that activation of SHIP1/MAPK/TNF-α pathway was necessary for upregulated NETosis in RA, which provided evidence for targeting SHIP1 in RA treatment.

Salivary Human β-Defensin 1-3 and Human α-Defensin-1 Levels in Relation to the Extent of Periodontal Disease and Tooth Loss in the Elderly

The oral innate immune response may diminish with aging. In the present study, the aim was to examine human β-defensin (hBD) 1-3 and human neutrophil peptide (HNP)-1 levels in the saliva of an elderly population to establish the extent of periodontal disease and tooth loss. A total of 175 individuals aged ≥ 65 years were divided into five groups based on the number of teeth with a pocket depth ≥ 4 mm as follows: 17 pocket-free individuals (Control), 55 individuals having 1-6 pocket teeth (PerioA), 33 individuals having 7-13 pocket teeth (PerioB), 29 individuals having at least 14 pocket teeth (PerioC), and 41 edentulous individuals. Their salivary defensin levels were measured with ELISA kits. The salivary HNP-1 levels were significantly higher in the Perio groups (PerioB: p < 0.001 and PerioC: p < 0.001) in comparison to the Control. The associations between salivary HNP-1 levels and the number of pocket teeth remained significant after adjustments for age, gender, level of education, and number of teeth. The salivary HNP and hBD levels differed in terms of their correlation to the extent of periodontal disease and tooth loss in the elderly.

Neutrophil dynamics and inflammaging in acute ischemic stroke: A transcriptomic review

Stroke is among the leading causes of death and disability worldwide. Restoring blood flow through recanalization is currently the only acute treatment for cerebral ischemia. Unfortunately, many patients that achieve a complete recanalization fail to regain functional independence. Recent studies indicate that activation of peripheral immune cells, particularly neutrophils, may contribute to microcirculatory failure and futile recanalization. Stroke primarily affects the elderly population, and mortality after endovascular therapies is associated with advanced age. Previous analyses of differential gene expression across injury status and age identify ischemic stroke as a complex age-related disease. It also suggests robust interactions between stroke injury, aging, and inflammation on a cellular and molecular level. Understanding such interactions is crucial in developing effective protective treatments. The global stroke burden will continue to increase with a rapidly aging human population. Unfortunately, the mechanisms of age-dependent vulnerability are poorly defined. In this review, we will discuss how neutrophil-specific gene expression patterns may contribute to poor treatment responses in stroke patients. We will also discuss age-related transcriptional changes that may contribute to poor clinical outcomes and greater susceptibility to cerebrovascular diseases.

Diagnostic and prognostic role of circulating neutrophil extracellular trap markers and prekallikrein in patients with high-grade serous ovarian cancer

Objective

Tumor-promoting inflammation is among the hallmarks of cancer. Prekallikrein is among the acute-phase reactants in the inflammatory response; moreover, neutrophils release nuclear contents into the extracellular space to create neutrophil extracellular traps (NET). We aimed to investigate the diagnostic and prognostic utilities of circulating plasma NET markers and prekallikrein for high-grade serous ovarian cancer (HGSOC).

Methods

Circulating levels of three NET markers (histone-DNA complex, cell-free DNA, and neutrophil elastase) and prekallikrein were measured in 75 patients with HGSOC and 23 healthy controls. We used an area under the receiver operating characteristic curve (AUC) analysis to investigate their diagnostic and prognostic utilities for HGSOC.

Results

Compared with healthy controls, patients with HGSOC showed significantly higher levels of the three NET markers and prekallikrein. Patients with advanced-stage HGSOC showed significantly higher levels of the cell-free DNA (87.4 vs. 79.5 ng/ml; P = 0.013), compared with those with early-stage HGSOC. Further, the levels of histone-DNA complex, neutrophil elastase, and prekallikrein did not significantly differ according to the cancer stage. All markers showed significant diagnostic utility. Notably, a logistic regression-based model that comprised all four markers showed the strongest diagnostic power (AUC, 0.966; 95% confidence interval [CI], 0.933-1.000). Specifically, neutrophil elastase was identified as an independent poor prognostic factor for overall survival (adjusted hazard ratio [aHR], 10.17; 95% CI, 1.09-94.97; P = 0.042) and progression-free survival (aHR, 14.47; 95% CI, 1.52-137.35; P = 0.020) in patients with HGSOC.

Conclusions

The levels of the three NET markers and prekallikrein might be novel diagnostic and prognostic markers for HGSOC.

Rituximab induces a flare-up of activated neutrophil extracellular traps under in vitro conditions

Purpose: During neutrophil extracellular traps (NET) formation granulocytes release a decondensed chromatin web that is studded with antimicrobial proteins. These NET engulf and kill pathogens like bacteria and fungi. NET formation is part of the innate immune response but can also contribute to the aggravation of autoimmune diseases, thrombosis, and cancer metastasis. Anti-NET therapeutics to prevent potentially harmful consequences of excessive NET formation are warranted.Materials and methods: Therefore, we stimulated NET formation with ionomycin in the peripheral blood of 25 healthy individuals and quantified NET with flow cytometry and fluorescence microscopy after exposure to five different anti-inflammatory and cytostatic drugs. NET were identified by their expression of myeloperoxidase, citrullinated histone H3, and (extracellular) DNA release.Results: The preliminary in vitro drug screening indicated that acetylsalicylic acid (ASA) might suppress (-3.82%), and rituximab might enhance (+10.52%) NET formation. To consolidate the screening results, we quantified NET after exposure to rituximab and ASA in the blood of nine additional healthy subjects. Rituximab showed a significant increased NET formation compared to the neutrophils treated with ASA (a mean of differences 3.96%; 95% CI 1.90-6.03%; p < .01) or compared to neutrophils without treatment (a mean of differences 4.39%; 95% CI 1.17-7.61%; p = .01). Contrary to the screening results ASA showed no significant suppression of NET formation in the consolidation experiments (a mean of differences 0.43%; 95% CI -1.27 to 2.12%; p = .58).Conclusions: We conclude that rituximab therapy might further trigger activated NET formation and should be applied with caution in patients with pro-inflammatory state and underlying autoimmune disease, thrombosis, or cancer.

Innate immunity dysregulation in aging eye and therapeutic interventions

The prevalence of eye diseases increases considerably with age, resulting in significant vision impairment. Although the pathobiology of age-related eye diseases has been studied extensively, the contribution of immune-related changes due to aging remains elusive. In the eye, tissue-resident cells and infiltrating immune cells regulate innate responses during injury or infection. But due to aging, these cells lose their protective functions and acquire pathological phenotypes. Thus, dysregulated ocular innate immunity in the elderly increases the susceptibility and severity of eye diseases. Herein, we emphasize the impact of aging on the ocular innate immune system in the pathogenesis of infectious and non-infectious eye diseases. We discuss the role of age-related alterations in cellular metabolism, epigenetics, and cellular senescence as mechanisms underlying altered innate immune functions. Finally, we describe approaches to restore protective innate immune functions in the aging eye. Overall, the review summarizes our current understanding of innate immune functions in eye diseases and their dysregulation during aging.

Co-delivery of paclitaxel (PTX) and docosahexaenoic acid (DHA) by targeting lipid nanoemulsions for cancer therapy

Breast cancer is one of the most common types of cancer in female patients with high morbidity and mortality. Multi-drug chemotherapy has significant advantages in the treatment of malignant tumors, especially in reducing drug toxicity, increasing drug sensitivity and reducing drug resistance. The objective of this research is to fabricate lipid nanoemulsions (LNs) for the co-delivery of PTX and docosahexaenoic acid (DHA) with folic acid (FA) decorating (PTX/DHA-FA-LNs), and investigate the anti-tumor activity of the PTX/DHA-FA-LNs against breast cancer both in vitro and in vivo. PTX/DHA-FA-LNs showed a steady release of PTX and DHA from the drug delivery system (DDS) without any burst effect. Furthermore, the PTX/DHA-FA-LNs exhibited a dose-dependent cytotoxicity and a higher rate of apoptosis as compared with the other groups in MCF-7 cells. The cellular uptake study revealed that this LNs were more readily uptaken by MCF-7 cells and M2 macrophages in vitro. Additionally, the targeted effect of PTX/DHA-FA-LNs was aided by FA receptor-mediated endocytosis, and its cytotoxicity was proportional to the cellular uptake efficiency. The anti-tumor efficiency results showed that PTX/DHA-FA-LNs significant inhibited tumor volume growth, prolonged survival time, and reduced toxicity when compared with the other groups. These results indicated that DHA increases the sensitivity of tumor cells and tumor-associated macrophages (ATM2) to PTX, and synergistic effects of folate modification in breast cancer treatment, thus PTX/DHA-FA-LNs may be a promising nanocarrier for breast cancer treatment.

NETosis is critical in patients with severe community-acquired pneumonia

Pneumonia is the fourth leading cause of death globally, and the reason for the high mortality rate of patients with severe community-acquired pneumonia (SCAP) remains elusive. Corticosteroid treatment reduces mortality in adults with SCAP but can cause numerous adverse events. Therefore, novel therapeutic targets need to be explored and new adjunctive immune drugs are urgently required. We analyzed the transcriptome data of peripheral blood leukocytes from patients with SCAP and healthy controls from three perspectives: differentially expressed genes, predicted functions of differentially expressed long non-coding RNAs, and transcriptional read-through. We discovered that the NETosis pathway was top-ranked in patients with SCAP caused by diverse kinds of pathogens. This provides a potential therapeutic strategy for treating patients. Furthermore, we calculated the correlation between the expression of genes involved in NETosis and the ratio of arterial oxygen partial pressure to fractional inspired oxygen. We identified four novel potential therapeutic targets for NETosis in patients with SCAP, including H4C15, H3-5, DNASE1, and PRKCB. In addition, a higher occurrence of transcriptional read-through is associated with a worse outcome in patients with SCAP, which probably can explain the high mortality rate of patients with SCAP.

Neutrophil Extracellular Traps in Asthma: Friends or Foes?

Asthma is a chronic inflammatory disease characterized by variable airflow limitation and airway hyperresponsiveness. A plethora of immune and structural cells are involved in asthma pathogenesis. The roles of neutrophils and their mediators in different asthma phenotypes are largely unknown. Neutrophil extracellular traps (NETs) are net-like structures composed of DNA scaffolds, histones and granular proteins released by activated neutrophils. NETs were originally described as a process to entrap and kill a variety of microorganisms. NET formation can be achieved through a cell-death process, termed NETosis, or in association with the release of DNA from viable neutrophils. NETs can also promote the resolution of inflammation by degrading cytokines and chemokines. NETs have been implicated in the pathogenesis of various non-infectious conditions, including autoimmunity, cancer and even allergic disorders. Putative surrogate NET biomarkers (e.g., double-strand DNA (dsDNA), myeloperoxidase-DNA (MPO-DNA), and citrullinated histone H3 (CitH3)) have been found in different sites/fluids of patients with asthma. Targeting NETs has been proposed as a therapeutic strategy in several diseases. However, different NETs and NET components may have alternate, even opposite, consequences on inflammation. Here we review recent findings emphasizing the pathogenic and therapeutic potential of NETs in asthma.

Immune senescence and periodontitis: From mechanism to therapy

Periodontitis is one of the most prevalent infectious inflammatory diseases, characterized by irreversible destruction of the supporting tissues of teeth, which is correlated with a greater risk of multiple systemic diseases, thus regarded as a major health concern. Dysregulation between periodontal microbial community and host immunity is considered to be the leading cause of periodontitis. Comprehensive studies have unveiled the double-edged role of immune response in the development of periodontitis. Immune senescence, which is described as age-related alterations in immune system, including a diminished immune response to endogenous and exogenous stimuli, a decline in the efficiency of immune protection, and even failure in immunity build-up after vaccination, leads to the increased susceptibility to infection. Recently, the intimate relationship between immune senescence and periodontitis has come into focus, especially in the aging population. In this review, both periodontal immunity and immune senescence will be fully introduced, especially their roles in the pathology and progression of periodontitis. Furthermore, novel immunotherapies targeting immune senescence are presented to provide potential targets for research and clinical intervention in the future.

Do neutrophil to lymphocyte ratio and platelet to lymphocyte ratio associate with frailty in elderly inpatient with comorbidity?

OBJECTIVE

Inflammation is one of the pathogenesis of frailty, Neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) are newly proposed inflammatory indicators. This study aimed to explore the relationship between NLR, PLR and frailty in elderly inpatient with comorbidity.

METHODS

Inpatient elderly with comorbidity in our geriatric department from January 2015 to December 2018 were selected, and three groups, which included frailty, pre-frailty and robust, were divided by 5-item FRAIL scale. General data of the patients were collected, and comprehensive geriatric assessment was performed. NLR and PLR were calculated by neutrophil, lymphocyte and platelet in blood. SPSS24.0 software was used for analysis.

RESULTS

CONCLUSION: Although results from the present study revealed associations between frailty and neutrophil and NLR in elderly inpatient with comorbidity, the potential role of these inflammation indicators on frailty needs further prospective investigation and researches involving larger population to improve its reliability.

Neutrophils in aging and aging‐related pathologies

Over the past millennia, life expectancy has drastically increased. While a mere 25 years during Bronze and Iron ages, life expectancy in many European countries and in Japan is currently above 80 years. Such an increase in life expectancy is a result of improved diet, life style, and medical care. Yet, increased life span and aging also represent the most important non-modifiable risk factors for several pathologies including cardiovascular disease, neurodegenerative diseases, and cancer. In recent years, neutrophils have been implicated in all of these pathologies. Hence, this review provides an overview of how aging impacts neutrophil production and function and conversely how neutrophils drive aging-associated pathologies. Finally, we provide a perspective on how processes of neutrophil-driven pathologies in the context of aging can be targeted therapeutically.

Neutrophil degranulation and severely impaired extracellular trap formation at the basis of susceptibility to infections of hemodialysis patients

BACKGROUND

Chronic kidney disease patients are at increased risk of mortality with cardiovascular diseases and infections as the two leading causes of death for end-stage kidney disease treated with hemodialysis (HD). Mortality from bacterial infections in HD patients is estimated to be 100-1000 times higher than in the healthy population.

METHODS

We comprehensively characterized highly pure circulating neutrophils from HD and healthy donors.

RESULTS

Protein levels and transcriptome of HD patients' neutrophils indicated massive neutrophil degranulation with a dramatic reduction in reactive oxygen species (ROS) production during an oxidative burst and defective oxidative cellular signaling. Moreover, HD neutrophils exhibit severely impaired ability to generate extracellular NET formation (NETosis) in NADPH oxidase-dependent or independent pathways, reflecting their loss of capacity to kill extracellular bacteria. Ectopic hydrogen peroxidase (H2O2) or recombinant human SOD-1 (rSOD-1) partly restores and improves the extent of HD dysfunctional neutrophil NET formation.

CONCLUSIONS

Our report is one of the first singular examples of severe and chronic impairment of NET formation leading to substantial clinical susceptibility to bacteremia that most likely results from the metabolic and environmental milieu typical to HD patients and not by common human genetic deficiencies. In this manner, aberrant gene expression and differential exocytosis of distinct granule populations could reflect the chronic defect in neutrophil functionality and their diminished ability to induce NETosis. Therefore, our findings suggest that targeting NETosis in HD patients may reduce infections, minimize their severity, and decrease the mortality rate from infections in this patient population.