Neutrophil-mediated IL-6 receptor trans-signaling and the risk of chronic obstructive pulmonary disease and asthma

Hemolysin from Aeromonas hydrophila enhances the host's serum enzyme activity and regulates transcriptional responses in the spleen of Cyprinus rubrofuscus

Aeromonas hydrophila is a conditional pathogen impacting public hygiene and safety. Hemolysin is a virulence factor of Aeromonas hydrophila that causes erythrocyte hemolysis, yet its transcriptional response to Cyprinus rubrofuscus remains unknown. Our investigation confirmed the hemolysis of hemolysin from A. hydrophila. Serum enzyme activity was evaluated weekly after C. rubrofuscus were immunized with hemolysin Ahh1. The results showed that the hemolysin enhances the serum superoxide dismutase (SOD), lysozyme (LZM), and catalase (CAT) activity, which reached a maximum on day 14. To elucidate the molecular interaction between hemolysin from A. hydrophila and the host, we performed transcriptome sequencing on the spleen of C. rubrofuscus 14 days post hemolysin infection. The total number of clean reads was 41.37 Gb, resulting in 79,832 unigenes with an N50 length of 1863 bp. There were 1982 significantly differentially expressed genes (DEGs), including 1083 upregulated genes and 899 downregulated genes. Transcript levels of the genes, such as LA6BL, CD2, and NLRC5, were significantly downregulated, while those of IL11, IL1R2, and IL8 were dramatically upregulated. The DEGs were mainly enriched in the immune disease, viral protein interaction with cytokine and cytokine receptor, and toll-like receptor pathways, suggesting that hemolysin stimulation can activate the transcriptional responses. RT-qPCR experiments results of seven genes, IL-8, STAT2, CTSK, PRF1, CXCL9, TLR5, and SACS, showed that their expression was highly concordant with RNA-seq data. We clarified for the first time the key genes and signaling pathways response to hemolysin from A. hydrophila, which offers strategies for treating and preventing diseases.

[Sivelestat sodium for treatment of patients with COVID-19-associated acute respiratory distress syndrome in intensive care unit: a single-center retrospective cohort study]

OBJECTIVE

To investigate the effect of sivelestat sodium on survival, oxygenation index, and serum markers for infection in critically ill patients with COVID-19-associated acute respiratory distress syndrome (ARDS).

METHODS

This retrospectively study was performed among the critically ill patients with COVID-19-associated ARDS admitted in the intensive care unit (ICU) at Nanfang Hospital, Southern Medical University. We collected the clinical data of the patients on the first day of ICU admission and on the day of discharge and laboratory tests results of interleukin-6 (IL-6), C-reactive protein (CRP) and procalcitonin (PCT) and oxygenation index on days 1, 3 and 7 following ICU admission. Propensity-score matching was used to match the patients receiving sivelestat sodium to those without the treatment. Cox proportional hazards model and linear regression analysis were used to assess the association of sivelestat sodium treatment with in-hospital mortality and the length of hospital stay.

RESULTS

A total of 199 patients with COVID-19-associated ARDS patients were included for data analysis. After propensity-score matching PSM, 35 patients receiving sivelestat sodium were matched to 70 patients without the treatment. Treatment with of sivelestat sodium was not associated with the reduction of in- hospital mortality (P=0.36), prolonged ICU stay (P=0.39), hospital stay (P=0.68) or improved oxygenation index (P>0.05) of the patients. No significant difference was found in serum CRP or PCT levels between the patients with and without sivelestat sodium treatment, but a significant reduction in IL-6 level was found in sivelestat sodium group (P=0.016).

CONCLUSION

Sivelestat sodium treatment is not correlated with the reduction of mortality or length of hospital stay, but is associated with reduced serum IL-6 level in patients with COVID-19-associated ARDS.

Perspective for Discovery of Small Molecule IL-6 Inhibitors through Study of Structure–Activity Relationships and Molecular Docking

Interleukin-6 (IL-6) is a proinflammatory cytokine that plays a key role in the pathogenesis and physiology of inflammatory and autoimmune diseases, such as coronary heart disease, cancer, Alzheimer's disease, asthma, rheumatoid arthritis, and most recently COVID-19. IL-6 and its signaling pathway are promising targets in the treatment of inflammatory and autoimmune diseases. Although, anti-IL-6 monoclonal antibodies are currently being used in clinics, huge unmet medical needs remain because of the high cost, administration-related toxicity, lack of opportunity for oral dosing, and potential immunogenicity of monoclonal antibody therapy. Furthermore, nonresponse or loss of response to monoclonal antibody therapy has been reported, which increases the importance of optimizing drug therapy with small molecule drugs. This work aims to provide a perspective for the discovery of novel small molecule IL-6 inhibitors by the analysis of the structure-activity relationships and computational studies for protein-protein inhibitors targeting the IL-6/IL-6 receptor/gp130 complex.

Pro-inflammatory cytokine responses to Naegleria fowleri infection

Naegleria fowleri, or the “brain-eating amoeba,” is responsible for a rare, but lethal, infection known as primary amoebic meningoencephalitis (PAM). Confirmed PAM cases have seen both a rise in numbers, as well as expansion of geographic range over the past several decades. There is no effective therapy for PAM and the clinical prognosis remains grim with a mortality rate over 95%. The role of the immune response in disease prevention and disease severity remains unclear. In this review, we explore potential roles of inflammatory immune responses to N. fowleri in disease pathogenesis with a primary focus on pro-inflammatory cytokines IL-1, IL-6, and TNFα. We also discuss modulating proinflammatory cytokines as an additional immune therapy in PAM treatment.

Development of eosinophilic granulomatosis with polyangiitis during the clinical course of microscopic polyangiitis: A case report

RATIONALE

Eosinophilic granulomatosis with polyangiitis (EGPA) is belongs to the antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) subgroups. EGPA, unlike other subgroups of AAV, including microscopic polyangiitis (MPA) and granulomatosis with polyangiitis, has the unique feature that both ANCA and eosinophilic inflammation are involved in its pathogenesis. Although AAV often relapses, there are currently no reports of EGPA developing during other subgroups of AAV. Herein, we document a case of EGPA that developed during the clinical course of MPA.

PATIENT CONCERNS

A 61-year-old Japanese woman was diagnosed with MPA based on interstitial lung disease and myeloperoxidase-ANCA positivity. After starting immunosuppression therapy, including prednisolone and tacrolimus, she was expected to achieve clinical remission. Nonetheless, she occasionally experienced MPA relapse, which required an increased prednisolone dose, rituximab, intravenous cyclophosphamide, and plasma exchange. Three years after MPA onset, she developed renal amyloidosis; thus, subcutaneous tocilizumab was added to her regimen. Following clinical remission, the administration interval of her subcutaneous tocilizumab therapy was extended and immunosuppressants were discontinued. She then developed bronchial asthma and mild eosinophilia (eosinophilic count: ~1000/μL). Further, a year later, she underwent total hip replacement using a titanium implant. Subsequently, she developed abnormal sensation in both hands, numbness, and muscle weakness, as well as palpable purpura and massive eosinophilia (eosinophilic count: ~8500/μL).

DIAGNOSIS

We diagnosed the patient with EGPA based on 5 items (asthma, multiple mononeuropathies, sinus abnormality, and extravascular eosinophils) of the 1990 American College of Rheumatology classification criteria.

INTERVENTIONS

We administered 400 mg/kg intravenous immunoglobulin for 5 consecutive days, 300 mg mepolizumab subcutaneously every 4 weeks, and 40 mg/day prednisolone following pulsed methylprednisolone therapy (1000 mg/day for 3 consecutive days).

OUTCOMES

After these treatments, the patient's symptoms improved, and eosinophilic count and inflammatory markers declined.

LESSONS

The present case suggests that EGPA can be induced by the development of eosinophilic inflammation in other subgroups of AAV.

The deciphering of the immune cells and marker signature in COVID-19 pathogenesis: An update

The precise interaction between the immune system and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical in deciphering the pathogenesis of coronavirus disease 2019 (COVID-19) and is also vital for developing novel therapeutic tools, including monoclonal antibodies, antivirals drugs, and vaccines. Viral infections need innate and adaptive immune reactions since the various immune components, such as neutrophils, macrophages, CD4⁺ T, CD8⁺ T, and B lymphocytes, play different roles in various infections. Consequently, the characterization of innate and adaptive immune reactions toward SARS-CoV-2 is crucial for defining the pathogenicity of COVID-19. In this study, we explain what is currently understood concerning the conventional immune reactions to SARS-CoV-2 infection to shed light on the protective and pathogenic role of immune response in this case. Also, in particular, we investigate the in-depth roles of other immune mediators, including neutrophil elastase, serum amyloid A, and syndecan, in the immunopathogenesis of COVID-19.

Pharmacological OGG1 inhibition decreases murine allergic airway inflammation

Background and aim: Allergic asthma is a complex inflammatory disease involving type 2 innate lymphoid cells, type 2 T helper cells, macrophages, and eosinophils. The disease is characterized by wheezing, dyspnea, coughing, chest tightness and variable airflow limitation for which there is no cure and is symptomatically treated with inhaled corticosteroids and β2-agonists. Molecular mechanisms underlying its complex pathogenesis are not fully understood. However, 8-oxoguanine DNA glycosylase-1 (OGG1), a DNA repair protein may play a central role, as OGG1 deficiency decreases both innate and allergic inflammation.

Methods: Using a murine ovalbumin (OVA) model of allergic airway inflammation we assessed the utility of an inhibitor of OGG1 (TH5487) in this disease context. Cytokines and chemokines, promoting immune cell recruitment were measured using a 23-multiplex assay and Western blotting. Additionally, immune cell recruitment to bronchi was measured using flow cytometry. Histological analyses and immunofluorescent staining were used to confirm immune cell influx and goblet cell hyperplasia of the airways. A PCR array was used to assess asthma-related genes in murine lung tissue following TH5487 treatment. Finally, airway hyperresponsiveness was determined using in vivo lung function measurement.

Results: In this study, administration of TH5487 to mice with OVA-induced allergic airway inflammation significantly decreased goblet cell hyperplasia and mucus production. TH5487 treatment also decreased levels of activated NF-κB and expression of proinflammatory cytokines and chemokines resulting in significantly lower recruitment of eosinophils and other immune cells to the lungs. Gene expression profiling of asthma and allergy-related proteins after TH5487 treatment revealed differences in several important regulators, including down regulation of Tnfrsf4, Arg1, Ccl12 and Ccl11, and upregulation of the negative regulator of type 2 inflammation, Bcl6. Furthermore, the gene Clca1 was upregulated following TH5487 treatment, which should be explored further due to its ambiguous role in allergic asthma. In addition, the OVA-induced airway hyperresponsiveness was significantly reduced by TH5487 treatment.

Conclusion: Taken together, the data presented in this study suggest OGG1 as a clinically relevant pharmacological target for the treatment of allergic inflammation.

Clinical Characteristics and Management Strategies for Adult Obese Asthma Patients

The rates of asthma and obesity are increasing concurrently in the United States. Epidemiologic studies demonstrate that the incidence of asthma increases with obesity. Furthermore, obese individuals have asthma that is more severe, harder to control, and resistant to standard medications. In fact, specific asthma-obesity phenotypes have been identified. Various pathophysiologic mechanisms, including mechanical, inflammatory, metabolic and microbiome-associated, are at play in promulgating the obese-asthma phenotypes. While standard asthma medications, such as inhaled corticosteroids and biologics, are currently used to treat obese asthmatics, they may have limited effectiveness. Targeting the underlying aberrant processes, such as addressing steroid resistance, microbiome, metabolic and weight loss approaches, may be helpful.

Novel potential treatable traits in asthma: Where is the research taking us?

Asthma is a complex, heterogeneous disease in which the underlying mechanisms are not fully understood. Patients are often grouped into phenotypes (based on clinical, biologic, and physiologic characteristics) and endotypes (based on distinct genetic or molecular mechanisms). Recently, patients with asthma have been broadly split into 2 phenotypes based on their levels of type 2 inflammation: type 2 and non-type 2 asthma. However, this approach is likely oversimplified, and our understanding of the non-type 2 mechanisms in asthma remains extremely limited. A better understanding of asthma phenotypes and endotypes may assist in development of drugs for new therapeutic targets in asthma. One approach is to identify "treatable traits," which are specific patient characteristics related to phenotypes and endotypes that can be targeted by therapies. This review will focus on emerging treatable traits in asthma and aim to describe novel patient subgroups and endotypes that may represent the next step in the search for new therapeutic approaches.

Pathway analysis of smoking-induced changes in buccal mucosal gene expression

Background

Cigarette smoking is the leading preventable cause of death worldwide, and it is the most common cause of oral cancers. This study aims to provide a deeper understanding of the molecular pathways in the oral cavity that are altered by exposure to cigarette smoke.

Methods

The gene expression dataset (accession number GSE8987, GPL96) of buccal mucosa samples from smokers (n = 5) and never smokers (n = 5) was downloaded from The National Center for Biotechnology Information's (NCBI) Gene Expression Omnibus (GEO) repository. Differential expression was ascertained via NCBI's GEO2R software, and Ingenuity Pathway Analysis (IPA) software was used to perform a pathway analysis.

Results

A total of 459 genes were found to be significantly differentially expressed in smoker buccal mucosa (p  < 0.05). A total of 261 genes were over-expressed while 198 genes were under-expressed. The top canonical pathways predicted by IPA were nitric oxide and reactive oxygen production at macrophages, macrophages/fibroblasts and endothelial cells in rheumatoid arthritis, and thyroid cancer pathways. The IPA upstream analysis predicted that the TP53, APP, SMAD3, and TNF proteins as well as dexamethasone drug would be top transcriptional regulators.

Conclusions

IPA highlighted critical pathways of carcinogenesis, mainly nitric oxide and reactive oxygen production at macrophages, and confirmed widespread injury in the buccal mucosa due to exposure to cigarette smoke. Our findings suggest that cigarette smoking significantly impacts gene pathways in the buccal mucosa and may highlight potential targets for treating the effects of cigarette smoking.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43042-022-00268-y.

An Overview of the Obese-Asthma Phenotype in Children

Asthma is the most common chronic disease in childhood. Overweight and obesity are included among the comorbidities considered in patients with difficult-to-treat asthma, suggesting a specific phenotype of the disease. Therefore, the constant increase in obesity prevalence in children and adolescents raises concerns about the parallel increase of obesity-associated asthma. The possible correlation between obesity and asthma has been investigated over the last decade by different authors, who suggest a complex multifactorial relationship. Although the particular non-eosinophilic endotype of obesity-related asthma supports the concept that high body weight precedes asthma development, there is ongoing debate about the direct causality of these two entities. A number of mechanisms may be involved in asthma in combination with obesity disease in children, including reduced physical activity, abnormal ventilation, chronic systemic inflammation, hormonal influences, genetics and additional comorbidities, such as gastroesophageal reflux and dysfunctional breathing. The identification of the obesity-related asthma phenotype is crucial to initiate specific therapeutic management. Besides the cornerstones of asthma treatment, lifestyle should be optimized, with interventions aiming to promote physical exercise, healthy diet, and comorbidities. Future studies should clarify the exact association between asthma and obesity and the mechanisms underlying the pathogenesis of these two related conditions with the aim to define personalized therapeutic strategies for asthma management in this population.

Prevention of IL-6 signaling ameliorates toluene diisocyanate-induced steroid-resistant asthma

BACKGROUND

Accumulating evidence indicated the crucial role for interleukin 6 (IL-6) signaling in the development of allergic asthma. Yet, the role of IL-6 signaling in toluene diisocyanate (TDI)-induced mixed granulocytic airway inflammation still remains unclear. Thus, the aims of this study were to dissect the role of IL-6 signaling and to evaluate the effect of tocilizumab on TDI-induced steroid-resistant asthma.

METHODS

TDI-induced asthma model was prepared and asthmatic mice were respectively given IL-6 monoclonal antibody, IL-6R monoclonal antibody (tocilizumab, 5 mg/kg, i.p. after each challenge) for therapeutic purposes or isotype IgG as control.

RESULTS

TDI exposure just elevated IL-6R expression in the infiltrated inflammatory cells around the airway, but increased glycoprotein 130 expression in the whole lung, especially in bronchial epithelium. Moreover, TDI inhalation increased airway hyperresponsiveness (AHR) to methacholine, coupled with mixed granulocytic inflammation, exaggerated epithelial denudation, airway smooth muscle thickening, goblet cell metaplasia, extensive submucosal collagen deposition, dysregulated Th2/Th17 responses, as well as innate immune responses and raised serum IgE. And almost all these responses except for raised serum IgE were markedly ameliorated by the administration of IL-6 neutralizing antibody or tocilizumab, but exhibited poor response to systemic steroid treatment. Also, TDI challenge induced nucleocytoplasm translocation of HMGB1 and promoted its release in the BALF, as well as elevated lung level of STAT3 phosphorylation, which were inhibited by anti-IL-6 and anti-IL-6R treatment.

CONCLUSIONS

Our data suggested that IL-6 monoclonal antibody and tocilizumab might effectively abrogate TDI-induced airway inflammation and remodeling, which could be used as a clinical potential therapy for patients with severe asthma.

Dissecting the IL-6 pathway in cardiometabolic disease: a Mendelian randomization study on both IL6 and IL6R

BACKGROUND

Chronic inflammation is a risk factor for cardiovascular disease. IL-6 signaling perturbation through IL-6 or IL-6R blockade may have potential benefit on cardiovascular risk. It is unknown whether targeting either IL-6 or IL-6 receptor may result in similar effects on CVD and adverse events. We compared the anticipated effects of targeting IL-6 and IL-6 receptor on cardiometabolic risk and potential side effects.

METHODS

We constructed four instruments: two main instruments with genetic variants in the IL6 and IL6R loci weighted for their association with CRP, and two after firstly filtering variants for their association with IL-6 or IL-6R expression. Analyses were performed for coronary artery disease (CAD), ischemic stroke, atrial fibrillation (AF), heart failure, type 2 diabetes (T2D), rheumatoid arthritis (RA), infection endpoints, and quantitative hematological, metabolic, and anthropometric parameters.

RESULTS

A 1 mg/L lower CRP by the IL6 instrument was associated with lower CAD (OR 0.86, 95% CI 0.77;0.96), AF, and T2D risk. A 1mg/L lower CRP by the IL6R instrument was associated with lower CAD (OR 0.90, 95% CI 0.86;0.95), any stroke and ischemic stroke, AF, RA risk and higher pneumonia risk. The eQTL filtered results were in concordance with the main results, but with wider confidence intervals.

CONCLUSIONS

IL-6 signalling perturbation by either IL6 or IL6R genetic instruments is associated with a similar risk reduction for multiple cardiometabolic diseases, suggesting that both IL-6 and IL-6R are potential therapeutic targets to lower CVD. Moreover, IL-6 rather than IL-6R inhibition might have a more favorable pneumonia risk.

A case of eosinophilic granulomatosis with polyangiitis after prolonged intervals of an anti-interleukin-6 receptor antibody for rheumatoid arthritis

An 83-year-old woman with a history of asthma complained of left abdominal pain and was admitted to our hospital. She was treated with tocilizumab, an anti-interleukin (IL)-6 receptor antibody, with a prolonged interval for rheumatoid arthritis (RA). Laboratory tests revealed a remarkable increase in eosinophil count and inflammatory markers with negative antineutrophil cytoplasmic antibodies. Echocardiography revealed pericardial fluid retention, and contrast-enhanced computed tomography revealed the thickening of the gastric antrum wall. Upper gastrointestinal endoscopy and biopsy revealed eosinophilic infiltration into the gastric mucosal epithelium. She was diagnosed with eosinophilic granulomatosis with polyangiitis (EGPA) with pericarditis and eosinophilic gastroenteritis. High-dose glucocorticoids with intermittent intravenous cyclophosphamide (IVCY) were initiated, resulting in remission. As IL-6 is involved in the pathogenesis of allergic diseases such as asthma, our case can provide insights into the pathogenic role of IL-6 in EGPA as the development of EGPA in our case may have been triggered by IL-6 signals enhanced with tocilizumab interval prolongation.

BMI trajectory in childhood is associated with asthma incidence at young adulthood mediated by DNA methylation

PURPOSE

Body mass index (BMI) is associated with asthma but associations of BMI temporal patterns with asthma incidence are unclear. Previous studies suggest that DNA methylation (DNAm) is associated with asthma status and variation in DNAm is a consequence of BMI changes. This study assessed the direct and indirect (via DNAm) effects of BMI trajectories in childhood on asthma incidence at young adulthood.

METHODS

Data from the Isle of Wight (IoW) birth cohort were included in the analyses. Group-based trajectory modelling was applied to infer latent BMI trajectories from ages 1 to 10 years. An R package, ttscreening, was applied to identify differentially methylated CpGs at age 10 years associated with BMI trajectories, stratified for sex. Logistic regressions were used to further exclude CpGs with DNAm at age 10 years not associated with asthma incidence at 18 years. CpGs discovered via path analyses that mediated the association of BMI trajectories with asthma incidence in the IoW cohort were further tested in an independent cohort, the Avon Longitudinal Study of Children and Parents (ALSPAC).

RESULTS

Two BMI trajectories (high vs. normal) were identified. Of the 442,474 CpG sites, DNAm at 159 CpGs in males and 212 in females were potentially associated with BMI trajectories. Assessment of their association with asthma incidence identified 9 CpGs in males and 6 CpGs in females. DNAm at 4 of these 15 CpGs showed statistically significant mediation effects (p-value < 0.05). At two of the 4 CpGs (cg23632109 and cg10817500), DNAm completely mediated the association (i.e., only statistically significant indirect effects were identified). In the ALSPAC cohort, at all four CpGs, the same direction of mediating effects were observed as those found in the IoW cohort, although statistically insignificant.

CONCLUSION

The association of BMI trajectory in childhood with asthma incidence at young adulthood is possibly mediated by DNAm.

IL-6 family cytokines in respiratory health and disease

Chronic lung diseases including asthma, chronic obstructive pulmonary disease (COPD) and lung fibrosis represent a major burden on healthcare systems with limited effective therapeutic options. Developing effective treatments for these debilitating diseases requires an understanding of how alterations at the molecular level affect lung macroscopic architecture. A common theme among these lung disorders is the presence of an underlying dysregulated immune system which can lead to sustained chronic inflammation. In this respect, several inflammatory cytokines have been implicated in the pathogenesis of lung diseases, thus leading to the notion that cytokines are attractive therapeutic targets for these disorders. In this review, we discuss and highlight the recent breakthroughs that have enhanced our understanding of the role of the interleukin (IL)-6 family of cytokines in lung homeostasis and chronic diseases including asthma, COPD, lung fibrosis and lung cancer.

Relationship of Soluble Interleukin-6 Receptors With Asthma: A Mendelian Randomization Study

Purpose: Emerging evidence suggests a potential role of interleukin-6 pathways—trans-signaling with soluble interleukin-6 receptors—in the asthma pathobiology. Despite the evidence for their associations with asthma, the causal role of soluble interleukin-6 receptors remains uncertain. We investigated the relations of soluble interleukin-6 receptors with asthma and its major phenotypes.

Methods: We conducted a two-sample Mendelian randomization study. As genetic instruments, we selected 33 independent cis-acting variants strongly associated with the level of plasma soluble interleukin-6 receptor in the INTERVAL study. To investigate the association of variants with asthma and its phenotypes, we used genome-wide association study data from the UK Biobank. We combined variant-specific causal estimates by the inverse-variance weighted method for each outcome.

Results: Genetically-instrumented soluble interleukin-6 receptor level was associated with a significantly higher risk of overall asthma (OR per one standard deviation increment in inverse-rank normalized soluble interleukin-6 receptor level, 1.02; 95%CI, 1.01–1.03; P = 0.004). Sensitivity analyses demonstrated consistent results and indicated no directional pleiotropy—e.g., MR-Egger (OR, 1.03; 95%CI, 1.01–1.05; P = 0.002; P_intercept =0.37). In the stratified analysis, the significant association persisted across asthma phenotypes—e.g., childhood asthma (OR, 1.05; 95%CI, 1.02–1.08; P < 0.001) and obese asthma (OR, 1.02; 95%CI 1.01–1.03; P = 0.007). Sensitivity analysis using 16 variants selected with different thresholds also demonstrated significant associations with overall asthma and its phenotypes.

Conclusion: Genetically-instrumented soluble interleukin-6 receptor level was causally associated with modestly but significantly higher risks of asthma and its phenotypes. Our observations support further investigations into identifying specific endotypes in which interleukin-6 pathways may play major roles.

Women with COPD from biomass smoke have reduced serum levels of biomarkers of angiogenesis and cancer, with EGFR predominating, compared to women with COPD from smoking

The main causes of COPD are smoking (COPD-TS) and exposure to biomass smoke (COPD-BS), considered as different phenotypes. The association of COPD-TS with lung cancer (LC) is well established, but not in COPD-BS. Thus, we studied the serum concentration of cytokines that participate in inflammation, angiogenesis, and tumor progression, used frequently as LC biomarkers, in women with COPD-BS compared with COPD-TS (n = 70). Clinical and physiological characteristics and the serum concentration (multiplex immunoassay) of 16 cytokines were evaluated. The analysis revealed that women with COPD-BS were shorter and older, and had lower concentrations of 12 serum cytokines: 6 proinflammatory and angiogenic IL-6Rα, PECAM-1, leptin, osteopontin, prolactin, and follistatin; and 6 that participate in angiogenesis and in tumor progression FGF-2, HGF, sVEGFR-2, sHER2/neu, sTIE-2, G-CSF, and SCF. Notably, there was a significant increase in sEGFR in women with COPD-BS compared to women with COPD-TS. PDGF-AA/BB and sTIE-2 did not change. These findings suggest that women with COPD-BS have markedly decreased proinflammatory, angiogenic, and tumor progression potential, compared to women with COPD-TS, with sEGFR as the predominant mediator, which might reflect a differential pattern of inflammation in women exposed to BS, favoring the development of chronic bronchitis.

Multi-omics links IL-6 trans-signalling with neutrophil extracellular trap formation and Haemophilus infection in COPD

BACKGROUND

IL-6 trans-signalling (IL-6TS) is emerging as a pathogenic mechanism in chronic respiratory diseases, however the drivers of IL-6TS in the airways and the phenotypic characteristic of patients with increased IL-6TS pathway activation remain poorly understood.

OBJECTIVE

Our aim was to identify and characterize COPD patients with increased airway IL-6TS and to elucidate the biological drivers of IL-6TS pathway activation.

METHODS

We used an IL-6TS-specific sputum biomarker profile (sIL-6R, IL-6, IL-1β, IL-8, MIP-1β) to stratify sputum data from patients with COPD (n=74; BEAT-COPD) by hierarchical clustering. The IL-6TS signature was related to clinical characteristics and sputum microbiome profiles. The induction of neutrophil extracellular trap formation (NETosis) and IL-6TS by Haemophilus influenzae were studied in human neutrophils.

RESULTS

Hierarchical clustering revealed an IL-6TS-high subset (n=24) of COPD patients, which shared phenotypic traits with an IL-6TS-high subset previously identified in asthma. The subset was characterized by increased sputum cell counts (p=0.0001), persistent sputum neutrophilia (p=0.0004), reduced quality of life (CRQ total score; p=0.008), and increased levels of pro-inflammatory mediators and MMPs in sputum. IL-6TS-high COPD patients showed an increase in Proteobacteria, with Haemophilus as the dominating genus. NETosis induced by H. influenzae was identified as a potential mechanism for increased soluble IL-6 receptor (sIL-6R) levels. This was supported by a significant positive correlation between sIL-6R and NETosis markers in bronchoalveolar lavage fluid from COPD patients.

CONCLUSION

IL-6TS pathway activation due to chronic colonization with Haemophilus may be an important disease driver in a subset of COPD patients.

Clinical Significance of Procalcitonin, C-Reactive Protein, and Interleukin-6 in Helping Guide the Antibiotic Use for Patients with Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Background

Currently, standards of antibiotic use in acute exacerbations of chronic obstructive pulmonary disease (AECOPD) patients are controversial.

Objective

The aim of the present study was to analyze the value of procalcitonin (PCT), C-reactive protein (CRP), and interleukin-6 (IL-6) levels to guide the antibiotic treatment of AECOPD patients.

Methods

A total of 371 patients with COPD or AECOPD were included in the study. Clinical and laboratory data were obtained at admission, 325 AECOPD patients and 46 sCOPD patients treated with antibiotics. The receiver operating curve (ROC) was used to evaluate the relationship between CRP, PCT, and IL-6.

Results

This study included medical record/case control 1, the COPD group (n = 46) and the AECOPD group (n = 325), and medical record control 2, the nonchanged antibiotic group (n = 203) and the changed antibiotic group (n = 61). In case 1, CRP, PCT, and IL-6 levels in the AECOPD group were higher than that in the control group (P < 0.05), while the result of ROC showed that IL-6 had higher AUC values (0.773) and higher sensitivity (71.7%) than other indicators. The specificity of PCT (93.5%) is higher than other indicators. In case 2, ROC curve results showed that the AUC value of IL-6 (0.771) was slightly higher than PCT and CRP. The sensitivity (85.2%) and specificity (65.5%) of CRP were higher than other indicators.

Conclusions

IL-6 and PCT were elevated in AECOPD patients, resulting in a higher diagnostic value for AECOPD. CRP had a higher diagnostic value for antibiotic use in AECOPD patients.

The Role of Cytokines and Chemokines in Shaping the Immune Microenvironment of Glioblastoma: Implications for Immunotherapy

Glioblastoma is the most common form of primary brain tumour in adults. For more than a decade, conventional treatment has produced a relatively modest improvement in the overall survival of glioblastoma patients. The immunosuppressive mechanisms employed by neoplastic and non-neoplastic cells within the tumour can limit treatment efficacy, and this can include the secretion of immunosuppressive cytokines and chemokines. These factors can play a significant role in immune modulation, thus disabling anti-tumour responses and contributing to tumour progression. Here, we review the complex interplay between populations of immune and tumour cells together with defined contributions by key cytokines and chemokines to these intercellular interactions. Understanding how these tumour-derived factors facilitate the crosstalk between cells may identify molecular candidates for potential immunotherapeutic targeting, which may enable better tumour control and improved patient survival.

Increased IL-6 and Potential IL-6 trans-signalling in the airways after an allergen challenge

BACKGROUND

In asthma, IL-6 is a potential cause of enhanced inflammation, tissue damage and airway dysfunction. IL-6 signalling is regulated by its receptor, which is composed of two proteins, IL-6R and GP130. In addition to their membrane form, these two proteins may be found as extracellular soluble forms. The interaction of IL-6 with soluble IL-6R (sIL-6R) can trigger IL-6 trans-signalling in cells lacking IL-6R. Conversely, the soluble form of GP130 (sGP130) competes with its membrane form to inhibit IL-6 trans-signalling.

OBJECTIVES

We aimed to analyse IL-6 trans-signalling proteins in the airways of subjects after an allergen challenge.

METHODS

We used a model of segmental bronchoprovocation with an allergen (SBP-Ag) in human subjects with allergy. Before and 48 h after SBP-Ag, bronchoalveolar lavages (BALs) allowed for the analysis of proteins in BAL fluids (BALFs) by ELISA, and membrane proteins on the surface of BAL cells by flow cytometry. In addition, we performed RNA sequencing (RNA-seq) and used proteomic data to further inform on the expression of the IL-6R subunits by eosinophils, bronchial epithelial cells and lung fibroblasts. Finally, we measured the effect of IL-6 trans-signalling on bronchial fibroblasts, in vitro.

RESULTS

IL-6, sIL-6R, sGP130 and the molar ratio of sIL-6R/sGP130 increased in the airways after SBP-Ag, suggesting the potential for enhanced IL-6 trans-signalling activity. BAL lymphocytes, monocytes and eosinophils displayed IL-6R on their surface and were all possible providers of sIL-6R, whereas GP130 was highly expressed in bronchial epithelial cells and lung fibroblasts. Finally, bronchial fibroblasts activated by IL-6 trans-signalling produced enhanced amounts of the chemokine, MCP-1 (CCL2).

CONCLUSION AND CLINICAL RELEVANCE

After a bronchial allergen challenge, we found augmentation of the elements of IL-6 trans-signalling. Allergen-induced IL-6 trans-signalling activity can activate fibroblasts to produce chemokines that can further enhance inflammation and lung dysfunction.

Interleukin-6 mediates neutrophil mobilization from bone marrow in pulmonary hypertension

Myeloid cells, such as neutrophils, are produced in the bone marrow in high quantities and are important in the pathogenesis of vascular diseases such as pulmonary hypertension (PH). Although neutrophil recruitment into sites of inflammation has been well studied, the mechanisms of neutrophil egress from the bone marrow are not well understood. Using computational flow cytometry, we observed increased neutrophils in the lungs of patients and mice with PH. Moreover, we found elevated levels of IL-6 in the blood and lungs of patients and mice with PH. We observed that transgenic mice overexpressing Il-6 in the lungs displayed elevated neutrophil egress from the bone marrow and exaggerated neutrophil recruitment to the lungs, resulting in exacerbated pulmonary vascular remodeling, and dysfunctional hemodynamics. Mechanistically, we found that IL-6-induced neutrophil egress from the bone marrow was dependent on interferon regulatory factor 4 (IRF-4)-mediated CX₃CR1 expression in neutrophils. Consequently, Cx₃cr1 genetic deficiency in hematopoietic cells in Il-6-transgenic mice significantly reduced neutrophil egress from bone marrow and decreased neutrophil counts in the lungs, thus ameliorating pulmonary remodeling and hemodynamics. In summary, these findings define a novel mechanism of IL-6-induced neutrophil egress from the bone marrow and reveal a new therapeutic target to curtail neutrophil-mediated inflammation in pulmonary vascular disease.

Asthma and Obesity: Two Diseases on the Rise and Bridged by Inflammation

Asthma and obesity are two epidemics affecting the developed world. The relationship between obesity and both asthma and severe asthma appears to be weight-dependent, causal, partly genetic, and probably bidirectional. There are two distinct phenotypes: 1. Allergic asthma in children with obesity, which worsens a pre-existing asthma, and 2. An often non allergic, late-onset asthma developing as a consequence of obesity. In obesity, infiltration of adipose tissue by macrophages M1, together with an increased expression of multiple mediators that amplify and propagate inflammation, is considered as the culprit of obesity-related inflammation. Adipose tissue is an important source of adipokines, such as pro-inflammatory leptin, produced in excess in obesity, and adiponectin with anti-inflammatory effects with reduced synthesis. The inflammatory process also involves the synthesis of pro-inflammatory cytokines such as IL-1β, IL-6, TNFα, and TGFβ, which also contribute to asthma pathogenesis. In contrast, asthma pro-inflammatory cytokines such as IL-4, IL-5, IL-13, and IL-33 contribute to maintain the lean state. The resulting regulatory effects of the immunomodulatory pathways underlying both diseases have been hypothesized to be one of the mechanisms by which obesity increases asthma risk and severity. Reduction of weight by diet, exercise, or bariatric surgery reduces inflammatory activity and improves asthma and lung function.

Identification of biomarkers associated with clinical severity of chronic obstructive pulmonary disease

We sought to identify the biomarkers related to the clinical severity of stage I to stage IV chronic obstructive pulmonary disease (COPD). Gene expression profiles from the blood samples of COPD patients at each of the four stages were acquired from the Gene Expression Omnibus Database (GEO, accession number: GSE54837). Genes showing expression changes among the different stages were sorted by soft clustering. We performed functional enrichment, protein-protein interaction (PPI), and miRNA regulatory network analyses for the differentially expressed genes. The biomarkers associated with the clinical classification of COPD were selected from logistic regression models and the relationships between TLR2 and inflammatory factors were verified in clinical blood samples by qPCR and ELISA. Gene clusters demonstrating continuously rising or falling changes in expression (clusters 1, 2, and 7 and clusters 5, 6, and 8, respectively) from stage I to IV were defined as upregulated and downregulated genes, respectively, and further analyzed. The upregulated genes were enriched in functions associated with defense, inflammatory, or immune responses. The downregulated genes were associated with lymphocyte activation and cell activation. TLR2, HMOX1, and CD79A were hub proteins in the integrated network of PPI and miRNA regulatory networks. TLR2 and CD79A were significantly correlated with clinical classifications. TLR2 was closely associated with inflammatory responses during COPD progression. Functions associated with inflammatory and immune responses as well as lymphocyte activation may play important roles in the progression of COPD from stage I to IV. TLR2 and CD79A may serve as potential biomarkers for the clinical severity of COPD. TLR2 and CD79A may also serve as independent biomarkers in the clinical classification in COPD. TLR2 may play an important role in the inflammatory responses of COPD.

Targeting neutrophils in asthma: A therapeutic opportunity?

Suppression of airway inflammation with inhaled corticosteroids has been the key therapeutic approach for asthma for many years. Identification of inflammatory phenotypes in asthma has moreover led to important breakthroughs, e.g. with specific targeting of the IL-5 pathway as add-on treatment in difficult-to-treat eosinophilic asthma. However, the impact of interfering with the neutrophilic component in asthma is less documented and understood. This review provides an overview of established and recent insights with regard to the role of neutrophils in asthma, focusing on research in humans. We will describe the main drivers of neutrophilic responses in asthma, the heterogeneity in neutrophils and how they could contribute to asthma pathogenesis. Moreover we will describe findings from clinical trials, in which neutrophilic inflammation was targeted. It is clear that neutrophils are important actors in asthma development and play a role in exacerbations. However, more research is required to fully understand how modulation of neutrophil activity could lead to a significant benefit in asthma patients with airway neutrophilia.

Therapeutic efficacy of IL-17A neutralization with corticosteroid treatment in a model of antigen-driven mixed-granulocytic asthma

Many mouse models of allergic asthma exhibit eosinophil-predominant cellularity rather than the mixed-granulocytic cytology in steroid-unresponsive severe disease. Therefore, we sought to implement a novel mouse model of antigen-driven, mixed-granulocytic, severe allergic asthma to determine biomarkers of the disease process and potential therapeutic targets. C57BL/6J wild-type, interleukin-6 knockout (IL-6-/-), and IL-6 receptor knockout (IL-6R-/-), mice were injected with an emulsion of complete Freund's adjuvant and house dust mite antigen (CFA/HDM) on day 1. Dexamethasone, a lymphocyte-depleting biological, or anti-IL-17A was administered during the intranasal HDM challenge on days 19-22. On day 23, the CFA/HDM model elicited mixed bronchoalveolar lavage (BAL) cellularity (typically 80% neutrophils and 10% eosinophils), airway hyperresponsiveness (AHR) to methacholine, diffusion impairment, lung damage, body weight loss, corticosteroid resistance, and elevated levels of serum amyloid A (SAA), pro-inflammatory cytokines, and T helper type 1/ T helper type 17 (Th1/Th17) cytokines compared with eosinophilic models of HDM-driven allergic airway disease. BAL cells in IL-6- or IL-6R-deficient mice were predominantly eosinophilic and associated with elevated T helper type 2 (Th2) and reduced Th1/Th17 cytokine production, along with an absence of SAA. Nevertheless, AHR remained in IL-6-deficient mice even when dexamethasone was administered. However, combined administration of anti-IL-17A and systemic corticosteroid significantly attenuated both overall and neutrophilic airway inflammation and also reduced AHR and body weight loss. Inhibition of IL-17A combined with systemic corticosteroid treatment during antigen-driven exacerbations may provide a novel therapeutic approach to prevent the pathological pulmonary and constitutional changes that greatly impact patients with the mixed-granulocytic endotype of severe asthma.

Effects of interleukin-6 receptor blockade on allergen-induced airway responses in mild asthmatics

Background

Interleukin (IL)-6 signalling has been implicated in allergic asthma by animal, genetic association and clinical studies. In this study, we tested the hypothesis that tocilizumab (TCZ), a human monoclonal antibody that blocks IL-6 signalling, can prevent the development of allergen-induced bronchoconstriction in humans.

Methods

We performed a randomised, double-blind, placebo-controlled study, with eligible participants completing two allergen inhalation challenge tests, conducted before and after treatment with a single dose of TCZ or placebo. The primary efficacy endpoint was the magnitude of the late asthmatic response recorded between 3 and 7 after allergen challenge. The secondary efficacy endpoint was the early asthmatic response, measured 20 min to 2 h after allergen challenge.

Results

A total of 66 patients enrolled between September 2014 and August 2017, when the trial was stopped for futility based on results from an interim analysis. Eleven patients fulfilled all eligibility criteria assessed at baseline and were subsequently randomised to the TCZ (n = 6) or placebo (n = 5) groups. Both the primary and secondary efficacy endpoints were not significantly different between the two groups. Five patients reported adverse events (AEs), three in the TCZ group (11 AEs) and two in the placebo group (four AEs). Only one AE was TCZ-related (mild neutropenia), and there were no serious AEs. Significant treatment effects were observed for serum levels of C-reactive protein, IL-6 and soluble IL-6R levels.

Conclusion

In a small proof-of-concept clinical trial, we found no evidence that a single dose of tocilizumab was able to prevent allergen-induced bronchoconstriction. (Trial registered in the Australian New Zealand Clinical Trials Registry, number ACTRN12614000123640).

Expansion of different subpopulations of CD26-/low T cells in allergic and non-allergic asthmatics

CD26 displays variable levels between effector (TH₁₇ ≫ TH₁ > TH₂ > Treg) and naïve/memory (memory > naïve) CD4⁺ T lymphocytes. Besides, IL-6/IL⁻6R is associated with TH₁₇-differentiation and asthma severity. Allergic/atopic asthma (AA) is dominated by TH₂ responses, while TH₁₇ immunity might either modulate the TH₂-dependent inflammation in AA or be an important mechanism boosting non-allergic asthma (NAA). Therefore, in this work we have compared the expression of CD26 and CD126 (IL-6Rα) in lymphocytes from different groups of donors: allergic (AA) and non-allergic (NAA) asthma, rhinitis, and healthy subjects. For this purpose, flow cytometry, haematological/biochemical, and in vitro proliferation assays were performed. Our results show a strong CD26-CD126 correlation and an over-representation of CD26⁻ subsets with a highly-differentiated effector phenotype in AA (CD4⁺CD26^−/low T cells) and NAA (CD4⁻CD26⁻ γδ-T cells). In addition, we found that circulating levels of CD26 (sCD26) were reduced in both AA and NAA, while loss of CD126 expression on different leukocytes correlated with higher disease severity. Finally, selective inhibition of CD26-mRNA translation led to enhanced T cell proliferation in vitro. These findings support that CD26 down-modulation could play a role in facilitating the expansion of highly-differentiated effector T cell subsets in asthma.

Loss of the adhesion G-protein coupled receptor ADGRF5 in mice induces airway inflammation and the expression of CCL2 in lung endothelial cells

Background

Adhesion G-protein coupled receptor F5 (ADGRF5) was recently identified as an essential regulator of pulmonary surfactant homeostasis in alveolar type II cells. We previously showed that in addition to abnormal surfactant accumulation, Adgrf5-deficient (Adgrf5^−/−) mice exhibit emphysema-like signs, suggesting a possible role for ADGRF5 in immune regulation. Here, we extended the phenotypic analysis of Adgrf5^−/− mice to help understand its biological role in the lung, and especially in immune regulation.

Methods

Histological features of lungs were evaluated by Alcian blue and Masson’s trichrome staining. Quantitative real-time PCR (qPCR) and western blot analyses were performed to analyze the differential expression of genes/proteins related to airway inflammation in lungs between wildtype and Adgrf5^−/− mice. Acid–base status was assessed by performing blood gas tests and urine pH measurements. Inflammatory cell counting was performed using Giemsa-stained bronchoalveolar lavage cells. Serum IgE concentrations were determined by enzyme-linked immunosorbent assay. The expression of Ccl2, S100a8, S100a9, and Saa3 in primary lung endothelial cells (ECs) was determined by qPCR and/or western blotting. Finally, the effect of administrating RS504393 to 2-week-old Adgrf5^−/− mice on gene expression in the lungs was analyzed by qPCR.

Results

Adgrf5^−/− mice exhibited several features of chronic airway inflammation (mucous cell metaplasia, mucus hyperproduction, subepithelial fibrosis, respiratory acidosis, high serum IgE, mast cell accumulation, and neutrophilia) in parallel with elevated expression of genes involved in mucous cell metaplasia (Muc5ac, Muc5b, Slc26a4, and Clca1), fibrosis (Tgfb1, Col1a1, Fn1, and Tnc), and type 2 immune response (Il4, Il5, Il13, IL-25, and IL-33) at 12 and/or 30 weeks of age. In contrast, mRNA expression of Ccl2, S100a8, and S100a9 was upregulated in embryonic or neonatal Adgrf5^−/− lungs as well as in lung ECs of Adgrf5^−/− mice at 1 week of age. RS504393 treatment suppressed the upregulation of S100a8, S100a9, Slc26a4, and Il5 in Adgrf5^−/− lungs.

Conclusions

Targeted disruption of ADGRF5 results in the development of airway inflammation, which is likely mediated by the type 2 immune response and possibly CCL2-mediated inflammation. ADGRF5 also has a potential role in the regulation of genes encoding CCL2 in lung ECs, thereby maintaining immune homeostasis.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-0973-6) contains supplementary material, which is available to authorized users.

COPD rat model is more susceptible to cold stress and PM2.5 exposure and the underlying mechanism

The purpose of this study is to verify the hypothesis that chronic obstructive pulmonary disease (COPD) model rat is more susceptible to cold stress and fine particulate matter (PM_2.5) exposure than the healthy rat, and explore the related mechanism. COPD rat model, established with cigarette smoke and lipopolysaccharide intratracheal instillation, were exposed to cold stress (0 °C) and PM_2.5 (0, 3.2, 12.8 mg/ml). After that, the levels of superoxide dismutase, inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), monocyte chemotactic protein 1 (MCP-1) and angiotensin Ⅱ (Ang-Ⅱ) in lung were measured, as well as the expression levels of lung 8-hydroxy-2-deoxyguanosine (8-OHdG), nuclear factor kappa B (NF-κB), heme-oxygenase-1 (HO-1) and nuclear factor erythroid-2-related factor 2 (Nrf2). There were significant positive relationships between PM_2.5 and lung level of iNOS, TNF-α, MCP-1 and Ang-Ⅱ, lung function and pathologic damage in COPD rats. The HO-1, NF-κB and 8-OHdG were found highly expressed in COPD rat lung, particularly at the higher PM_2.5 dose of cold stress groups, while Nrf2 was found declined. Thus, COPD rats may be more susceptible to cold stress and PM_2.5 exposure. Cold stress may aggravate PM_2.5-induced toxic effects in the lung of COPD rats through increasing Ang-Ⅱ/NF-κB signaling pathway and suppressing Nrf2 signaling pathway.

Epithelial IL-6 trans-signaling defines a new asthma phenotype with increased airway inflammation

BACKGROUND

Although several studies link high levels of IL-6 and soluble IL-6 receptor (sIL-6R) to asthma severity and decreased lung function, the role of IL-6 trans-signaling (IL-6TS) in asthmatic patients is unclear.

OBJECTIVE

We sought to explore the association between epithelial IL-6TS pathway activation and molecular and clinical phenotypes in asthmatic patients.

METHODS

An IL-6TS gene signature obtained from air-liquid interface cultures of human bronchial epithelial cells stimulated with IL-6 and sIL-6R was used to stratify lung epithelial transcriptomic data (Unbiased Biomarkers in Prediction of Respiratory Disease Outcomes [U-BIOPRED] cohorts) by means of hierarchical clustering. IL-6TS-specific protein markers were used to stratify sputum biomarker data (Wessex cohort). Molecular phenotyping was based on transcriptional profiling of epithelial brushings, pathway analysis, and immunohistochemical analysis of bronchial biopsy specimens.

RESULTS

Activation of IL-6TS in air-liquid interface cultures reduced epithelial integrity and induced a specific gene signature enriched in genes associated with airway remodeling. The IL-6TS signature identified a subset of patients with IL-6TS-high asthma with increased epithelial expression of IL-6TS-inducible genes in the absence of systemic inflammation. The IL-6TS-high subset had an overrepresentation of frequent exacerbators, blood eosinophilia, and submucosal infiltration of T cells and macrophages. In bronchial brushings Toll-like receptor pathway genes were upregulated, whereas expression of cell junction genes was reduced. Sputum sIL-6R and IL-6 levels correlated with sputum markers of remodeling and innate immune activation, in particular YKL-40, matrix metalloproteinase 3, macrophage inflammatory protein 1β, IL-8, and IL-1β.

CONCLUSIONS

Local lung epithelial IL-6TS activation in the absence of type 2 airway inflammation defines a novel subset of asthmatic patients and might drive airway inflammation and epithelial dysfunction in these patients.

Splenectomy protects aged mice from injury after experimental stroke

Elderly stroke patients and aged animals subjected to experimental stroke have significantly worse functional recovery and higher mortality compared to younger subjects. Activation of the peripheral immune system is known to influence stroke outcome. Prior studies have shown that splenectomy reduces ischemic brain injury in young mice. As immune function changes with aging, it is unclear whether splenectomy will confer similar benefits in aged animals. We investigated the contribution of spleen to brain injury after cerebral ischemia in aged male mice. Splenic architecture and immune cell composition were altered in aged mice. Splenectomy 2 weeks before stroke resulted in improved neurobehavioral and infarct outcomes in aged male mice. In addition, there was a reduction in peripheral immune cell infiltration into the brain and decreased levels of peripheral inflammatory cytokines after stroke in aged splenectomized mice. Splenectomy immediately after reperfusion also improved behavioral and infarct outcomes. This study suggests that inhibition of the splenic immune response is a translationally relevant target to pursue for stroke treatment in aged individuals.