Neutrophil Extracellular Traps Research Articles

Extracellular traps in peripheral blood mononuclear cell fraction in childhood-onset systemic lupus erythematosus.

Although the role of low-density granulocytes (LDGs), neutrophils in the peripheral blood mononuclear cell (PBMC) fraction, and neutrophil extracellular traps (NETs) in assessing lupus disease severity is acknowledged, data specific to childhood-onset lupus remains scarce. This study analyzed 46 patients with childhood-onset systemic lupus erythematosus (82.6% females, mean age 14.5 ± 0.3 years), including 26 cases with normal complement levels and 20 with low complement levels, along with 20 healthy adult volunteers. Key parameters that distinguished healthy volunteers from lupus patients and differentiated between lupus patients with low and normal complement were serum interferon (IFN)-α, serum citrullinated histone 3 (CitH3), and extracellular traps (ETs) in LDGs. However, NETs (assessed by nuclear staining morphology), LDG abundance, and other parameters (such as endotoxemia, cytokines, and double-stranded (ds) DNA) did not show such differentiation. When lipopolysaccharide (LPS) was administered to LDGs in the PBMC fraction, it induced ETs in both low and normal complement groups, indicating the inducible nature of ETs. In adult healthy volunteers, activation by recombinant IFN-α or dsDNA in isolated neutrophils induced LDGs and NETs (identified using immunofluorescent staining for CitH3, myeloperoxidase, and neutrophil elastase) at 45min and 3h post-stimulation, respectively. Additionally, approximately half of the LDGs underwent late apoptosis at 3h post-stimulation, as determined by flow cytometry analysis. Activation by IFN-α or dsDNA in LDGs also led to a more pronounced expression of CD66b, an adhesion molecule, compared to regular-density neutrophils, suggesting higher activity in LDGs. In conclusion, IFN-α and/or dsDNA in serum may transform regular-density neutrophils into LDGs before progressing to NETosis and apoptosis, potentially exacerbating lupus severity through cell death-induced self-antigens. Therefore, LDGs and ETs in LDGs could provide deeper insights into the pathophysiology of childhood-onset lupus.

Distinctive CD39+CD9+ lung interstitial macrophages suppress IL-23/Th17-mediated neutrophilic asthma by inhibiting NETosis.

The IL-23-Th17 axis is responsible for neutrophilic inflammation in various inflammatory diseases. Here, we discover a potential pathway to inhibit neutrophilic asthma. In our neutrophil-dominant asthma (NDA) model, single-cell RNA-seq analysis identifies a subpopulation of CD39+CD9+ interstitial macrophages (IMs) suppressed by IL-23 in NDA conditions but increased by an IL-23 inhibitor αIL-23p19. Adoptively transferred CD39+CD9+ IMs suppress neutrophil extracellular trap formation (NETosis), a representative phenotype of NDA, and also Th17 cell activation and neutrophilic inflammation. CD39+CD9+ IMs first attach to neutrophils in a CD9-dependent manner, and then remove ATP near neutrophils that contribute to NETosis in a CD39-dependent manner. Transcriptomic data from asthmatic patients finally show decreased CD39+CD9+ IMs in severe asthma than mild/moderate asthma. Our results suggest that CD39+CD9+ IMs function as a potent negative regulator of neutrophilic inflammation by suppressing NETosis in the IL-23-Th17 axis and can thus serve as a potential therapeutic target for IL-23-Th17-mediated neutrophilic asthma.

CXCR2 mediated trafficking of neutrophils and neutrophil extracellular traps are required for myelin clearance after a peripheral nerve injury

Neutrophils are a vital part of the innate immune system. Many of their functions eliminate bacteria & viruses, like neutrophil extracellular traps (NETs), which trap bacteria, enhancing macrophage phagocytosis. It was surprising when it was demonstrated that neutrophils are a part of Wallerian degeneration, a process that is essential for nerve regeneration after a nerve injury. It is not known what signals attract neutrophils into the nerve and how they aid Wallerian degeneration. Neutrophils accumulate in the distal nerve within one day after an injury and are found in the nerve from one to three days. We demonstrate that CXCR2 mediates the trafficking of neutrophils into the distal nerve, and without CXCR2 Wallerian degeneration, as indicated by luxol fast blue staining, was reduced seven days after a sciatic nerve crush or transection injury. NETs were detected in the distal nerve after a sciatic nerve transection. NET formation has been shown to require protein arginine deiminase 4 (PAD4), which citrullinates histone 3. Inhibiting PAD4 reduced NET formation significantly in the distal nerve at two days and myelin clearance at seven days indicating that NETs aid myelin clearance. These results demonstrate another function for NETs other than clearing pathogens. Neutrophils have been detected after injuries to the central nervous system and diseases in humans and animal models. Our results demonstrate neutrophils aid myelin clearance, suggesting a role for their presence in central nervous system injuries and diseases.

The Impact of Disease Severity on the Serum Levels of Significant Neutrophil Extracellular Trap (NET) Proteins in Patients with Psoriasis.

Psoriasis is an inflammatory skin disease with various symptoms of differing severities and with the reported prominent involvement of neutrophil extracellular traps (NETs). The excitation of neutrophils, e.g., by interleukin 8 (IL-8) or lipopolysaccharide (LPS), leads to the citrullination of histones and the release of protein-DNA complexes into the extracellular space, where they are digested by DNases. Our aim was to explore data on the levels of protein-complexed DNAs neutrophil elastase-DNA (NE-DNA) and myeloperoxidase-DNA (MPO-DNA), citrullinated histones (citH2, citH3, citH4), and NET-degrading enzyme DNase I in the serum of psoriatic patients with varying severities of clinical symptoms assessed with the Psoriasis Area Severity Index (PASI), Body Surface Area (BSA), and Dermatology Life Quality Index (DLQI) scores. The levels of factors were detected in 52 patients with psoriasis and 22 healthy volunteers by the enzyme-linked immunosorbent assay (ELISA). The results showed the elevated levels of NE-DNA, MPO-DNA, citH3, and DNase I in the patients with psoriasis compared to healthy volunteers (p < 0.05). Additionally, changes were noticed in the levels of NE-DNA, citH3, and DNase I, depending on the severity of symptoms (p < 0.05). In mild psoriasis (PASI < 10, BSA < 10, DLQI < 10), the suppressing activity of the enzyme caused the impaired ability to remove the physiological level of NETs, whereas in moderate to severe psoriasis (PASI ≥ 10, BSA ≥ 10, DLQI ≥ 10), the enhanced activity of DNase I failed to remove NETs due to the observed overexpression. It may, thus, be concluded that the mechanism of action of NETs, which play an undeniable role in psoriatic diseases, seem to follow two different paths depending on the severity of disease, which may be crucial in selecting potential anti-NET treatment methods.

Evidence of Neutrophils and Neutrophil Extracellular Traps in Human NMSC with Regard to Clinical Risk Factors, Ulceration and CD8+ T Cell Infiltrate.

Non-melanoma skin cancers (NMSC), including basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and Merkel cell carcinoma (MCC), are increasingly common and present significant healthcare challenges. Neutrophil extracellular traps (NETs), chromatin fibers expulsed by neutrophil granulocytes, can promote immunotherapy resistance via an impairment of CD8+ T cell-mediated cytotoxicity. Here, to identify a potential therapeutic target, we investigate the expulsion of NETs and their relation to CD8+ T cell infiltration in NMSC. Immunofluorescence staining for neutrophils (CD15) and NETs (H3cit), as well as immunohistochemistry for cytotoxic T cells (CD8+) on human cSCCs (n = 24), BCCs (n = 17) and MCCs (n = 12), revealed a correlation between neutrophil infiltration and ulceration diameter in BCC and MCC, but not in cSCC. In BCC and cSCC, neutrophil infiltration also correlated with the cross-sectional area (CSA). NETs were not associated with established risk factors but with the presence of an ulceration, and, in cSCC, with abscess-like structures. CD8+ T cell infiltration was not reduced in tumors that were NET-positive nor in those with a denser neutrophil infiltration. This study is the first to report and characterize NETs in NMSC. Thus, it gives an incentive for further research in this relevant yet understudied topic.

PAD4 Inhibitor-Loaded Layered Double Hydroxide Nanosheets as a Multifunctional Nanoplatform for Photodynamic Therapy-Mediated Tumor Metastasis Treatment.

Photodynamic therapy (PDT) is demonstrated to be effective in inducing antitumor immune responses for tumor metastasis treatment. However, tumor hypoxia, inferior tissue penetration of light, and low singlet oxygen (1O2) quantum yield significantly hamper the efficacy of PDT, thus weakening its immune function. Moreover, PDT-mediated neutrophil extracellular traps (NETs) formation can further reduce the therapeutic effectiveness. Herein, the use of defect-rich CoMo-layered double hydroxide (DR-CoMo-LDH) nanosheets as a carrier to load a typical peptidyl arginine deiminase 4 inhibitor, i.e., YW4-03, to construct a multifunctional nanoagent (403@DR-LDH) for PDT/immunotherapy, is reported. Specifically, 403@DR-LDH inherits excellent 1O2 generation activity under 1550nm laser irradiation and improves the half-life of YW4-03. Meanwhile, 403@DR-LDH plus 1550nm laser irradiation can stimulate immunogenic cell death to promote the maturation of dendric cells and activation/infiltration of T cells and significantly downregulate H3cit protein expression to inhibit NETs formation, synergistically promoting the antitumor metastasis effect. Taken together, 403@DR-LDH can kill cancer cells and inhibit tumor growth/metastasis under 1550nm laser irradiation. Single-cell analysis indicates that 403@DR-LDH can regulate the ratio of immune cells and immune-related proteins to improve the tumor immune microenvironment, showing strong efficacy to inhibit the tumor growth, metastasis, and recurrence.

Fibroblast Growth Factor 21 Suppressed Neutrophil Extracellular Traps Induced by Myocardial Ischemia/Reperfusion Injury via Adenosine Monophosphate-Activated Protein Kinase.

Previous investigations have established the anti-inflammatory properties of fibroblast growth factor 21 (FGF21). However, the specific mechanism through which FGF21 mitigates myocardial ischemia/reperfusion (I/R) injury by inhibiting neutrophil extracellular traps (NETs) remains unclear. A mice model of myocardial I/R injury was induced, and myocardial tissue was stained with immunofluorescence to assess NETs. Serum NETs levels were quantified using a PicoGreen kit. In addition, the expression levels of adenosine monophosphate (AMP)-activated protein kinase (AMPK) and FGF21 were evaluated by Wes fully automated protein blotting quantitative analysis system. Moreover, a hypoxia/reoxygenation (H/R) model was established using AMPK inhibitor and agonist pretreated H9c2 cells to further explore the relationship between FGF21 and AMPK. Compared with the control group, serum NETs levels were significantly higher in I/R mice, and a large number of NETs were formed in myocardial tissues (97.63 ± 11.45 vs. 69.65 ± 3.33, P < 0.05). However, NETs levels were reversed in FGF21 pretreated mice (P < 0.05). Further studies showed that FGF21 enhanced AMPK expression, which was significantly increased after inhibition of AMPK and decreased after promotion of AMPK (P < 0.05). FGF21 may exert cardioprotective effects by inhibiting I/R injury-induced NETs via AMPK.

Didang decoction attenuates cancer-associated thrombosis by inhibiting PAD4-dependent NET formation in lung cancer.

This research aims to investigate the impact of Didang decoction (DD) on the formation of neutrophil extracellular traps (NETs) and cancer-associated thrombosis in lung cancer. BALB/c nude mice were used to establish xenograft models for inducing deep vein thrombosis. Tumor growth and thrombus length were assessed. The impact of DD on NET generation was analyzed using enzyme-linked immunosorbent assay, immunofluorescence staining, quantitative real-time PCR, and western blot analysis, both in vivo and in vitro. CI-amidine, a PAD4 inhibitor, was employed to evaluate the role of PAD4 in the generation of NETs. In vivo studies demonstrated that treatment with DD reduced tumor growth, inhibited thrombus formation, and decreased the levels of NET markers in the serum, tumor tissues, neutrophils, and thrombus tissues of mice. Additional data indicated that DD could suppress neutrophil counts, the release of tissue factor (TF), and the activation of thrombin-activated platelets, all of which contributed to increased formation of NETs in mouse models. In vitro, following incubation with conditioned medium (CM) derived from Lewis lung carcinoma cells, the expression of NET markers in neutrophils was significantly elevated, and an extracellular fibrous network structure was observed. Nevertheless, these NET-associated changes were partially counteracted by DD. Additionally, CI-amidine reduced the expression of NET markers in CM-treated neutrophils, consistent with the effects of DD. Collectively, DD inhibits cancer-associated thrombosis in lung cancer by decreasing PAD4-dependent NET formation through the regulation of TF-mediated thrombin-platelet activation. This presents a promising therapeutic strategy for preventing and treating venous thromboembolism in lung cancer.

Dysregulation of neutrophil extracellular traps (NETs)-related genes in the pathogenesis of diabetic kidney disease - Results from bioinformatics analysis and translational studies

The role of Neutrophil extracellular traps (NETs) in the immunopathogenesis of Diabetic Kidney Disease (DKD) remains elusive. We used a machine learning approach to identify differentially expressed genes (DEGs) associated with NETs in human DKD kidney biopsy datasets and validated the results using single-nucleus RNA sequencing datasets. The expressions of these candidate genes and related cytokines were verified in blood obtained from DKD patients. Three NETs-associated genes (ITGAM, ITGB2 and TLR7) were identified, which all showed significant upregulation in both glomerular and tubulointerstitial compartments in human DKD kidneys. DKD patients showed significantly higher number of activated neutrophils with increased ITGAM and ITGB2 expression, higher serum IL-6 but lower IL-10, compared to healthy controls (p all <0.01). This study suggests that dysregulation of NETs-associated genes ITGAM and ITGB2 are related to the pathogenesis of DKD, and may serve as novel diagnostic markers and therapeutic targets in DKD.

Identification of NET formation and the renoprotective effect of degraded NETs in lupus nephritis.

To explore molecular biomarkers associated with the pathophysiology and therapy of lupus nephritis (LN), we conducted a joint analysis of transcriptomic data from 40 peripheral blood mononuclear cells (PBMCs) (GSE81622) and 21 kidney samples (GSE112943) from the Gene Expression Omnibus database using bioinformatics. A total of 976 and 2,427 differentially expressed genes (DEGs) were identified in PBMCs and renal tissues. Seven and two functional modules closely related to LN were identified. Further enrichment analysis revealed that the neutrophil activation pathway was highly active in both PBMCs and the kidney. Subsequently, 16 core genes closely associated with LN were verified by protein-protein interaction screening and quantitative PCR. In vitro cell models and MRL/lpr mouse models confirmed that the abnormal expression of these core genes was closely linked to neutrophil extracellular traps (NETs) generated by neutrophil activation, while degradation of NETs led to downregulation of core gene expression, thereby improving pathological symptoms of LN. Therefore, identification of patients with systemic lupus erythematosus exhibiting abnormal expression patterns for these core genes may serve as a useful indicator for kidney involvement. In addition, targeting neutrophils to modulate their activation levels and inhibit aberrant expression of these genes represents a potential therapeutic strategy for treating LN. NEW & NOTEWORTHY The mechanisms by which immune cells cause kidney injury in lupus nephritis are poorly understood. We integrated and analyzed the transcriptomic features of PBMCs and renal tissues from the GEO database to identify key molecular markers associated with neutrophil activation. We confirmed that neutrophil extracellular traps (NETs) formed by neutrophil activation promoted the upregulation of key genes in cell and animal models. Targeted degradation of NETs significantly ameliorated kidney injury in MRL/lpr mice.

Response of Circulating Free Cellular DNA to Repeated Exercise in Men with Type 1 Diabetes Mellitus

Background: Intense exercise leads to neutrophil extracellular traps (NETs) formation, which triggers cell disintegration. NET, as well as other processes of apoptosis, necrosis, and spontaneous secretion, result in increased levels of cell-free DNA (cf-DNA) in the circulation. An increment of cf-DNA is also observed in autoimmune diseases, such as type 1 diabetes mellitus (T1DM). Repeated exhaustive exercises are an impulse for physiological adaptation; therefore, in this case–control study, we compared the exercise-induced increase in cf-DNA in men with T1DM and healthy controls to determine the development of the tolerance to exercise. Methods: Volunteers performed a treadmill run to exhaustion at a speed matching 70% of their personal VO2 max at three consecutive visits, separated by a 72 h resting period. Blood was collected before and after exercise for the determination of plasma cell-free nuclear and mitochondrial DNA (cf n-DNA, cf mt-DNA) by real-time PCR, blood cell count and metabolic markers. Results: Each bout of exhaustive exercise induced a great elevation of cf n-DNA levels. An increase in cf mt-DNA was observed after each run. However, the significance of the increase was noted only after the second bout in T1DM participants (p &lt; 0.02). Changes in cf-DNA concentration were transient and returned to baseline values during 72 h of resting. The exercise-induced increment in circulating cf n-DNA and cf mt-DNA was not significantly different between the studied groups (p &gt; 0.05). Conclusions: Cf-DNA appears to be a sensitive marker of inflammation, with a lower post-exercise increase in individuals with T1DM than in healthy men.

Synergistic potentiation of the anti-metastatic effect of a Ginseng-Salvia miltiorrhiza herbal pair and its biological ingredients via the suppression of CD62E-dependent neutrophil infiltration and NET formation.

The combination of the roots of ginseng and Salvia miltiorrhiza is an effective approach for treating metastatic cancer in patients with Qi stagnation and blood stasis patterns. However, the molecular mechanism underlying the combined use of ginseng and Salvia miltiorrhiza is unknown. This study unveils the pharmacological foundation of ginseng and Salvia miltiorrhiza by examining the involvement of neutrophils in the critical process of tumor hematogenous metastasis. Additionally, by employing a reverse pharmacology research model (effect-target-constituent), potential potent components were screened, and the dominant component formulations were determined. An experimental lung metastatic model was constructed to compare the antitumor effects of ginseng and Salvia miltiorrhiza. RNA sequencing was employed to identify pivotal biological events and key targets, while the detection of CD62E expression and neutrophil extracellular traps (NETs) release was used to screen for effective substances in ginseng and Salvia miltiorrhiza. In addition, a comprehensive array of in vitro and in vivo experiments was conducted to explore the underlying mechanisms and therapeutic significance. Compared with single-herb use, the use of ginseng or Salvia miltiorrhiza significantly reduced tumor metastasis, which was accompanied by reduced neutrophil infiltration into the lungs. Cryptotanshinone (CPT), an active constituent of Salvia miltiorrhiza, can inhibit neutrophil adhesion and recruitment to lung tissue by downregulating the expression of E-selectin (CD62E) in endothelial cells. Moreover, the ginseng -derived ginsenoside Rg1 mitigated the formation of NETs in lung tissues and reversed the protumor effects of NETs. We further explored the efficacy of combination therapy with Rg1 and CPT, which also reduced tumor metastasis in vivo. Ginseng and Salvia miltiorrhiza exhibited a mutual potentiation of the anti-metastatic effect by suppressing both early and late stages of neutrophil-initiated metastasis cascade. Rg1 and CPT represent the synergistic ingredients from ginseng and Salvia miltiorrhiza, respectively.

Metabolic dysregulation-triggered neutrophil extracellular traps exacerbate acute liver failure.

Acute liver failure (ALF) is an acute liver disease with a high mortality rate in clinical practice, characterized histologically by extensive hepatocellular necrosis and massive neutrophil infiltration. However, the role of these abnormally infiltrating neutrophils during ALF development is unclear. Here, in an ALF mouse model, metabolites were identified that promote the formation of neutrophil extracellular traps (NETs) in the liver, subsequently influencing macrophage differentiation and disease progression. ALF occurs with abnormalities in hepatic and intestinal metabolites. Abnormal metabolites (LTD4 and glutathione) can directly, or indirectly via reactive oxygen species, promote NET formation of infiltrating neutrophils, which subsequently regulate macrophages in a pro-inflammatory M1-like state, inducing an amplification of the destructive effects of inflammation. Together, this study provides new insights into the role of NETs in the pathogenesis of ALF.

Remote Ischemic Preconditioning Can Prevent Contrast-Induced AKI (CIAKI) by Reducing Neutrophil Extracellular Traps (NETs)

Remote Ischemic Preconditioning Can Prevent Contrast-Induced AKI (CIAKI) by Reducing Neutrophil Extracellular Traps (NETs)

APEX1 in intestinal epithelium triggers neutrophil infiltration and intestinal barrier damage in ulcerative colitis

Ulcerative colitis (UC) can lead to the generation of large amounts of reactive oxygen species and DNA damage. DNA repair caused by base excision repair (BER) enzymes is an important mechanism for maintaining genomic integrity. However, the specific relationship between the function of BER enzymes and UC remains unclear. To address this, we conducted a study on non-cancerous colon tissue from patients with UC, focusing on the role of apurinic/apyrimidinic endonuclease 1 (APEX1) in BER to explore its significance in the progression of UC. Our research found that the expression of APEX1 in epithelium cells was significantly correlated to the severity of inflammatory bowel disease (IBD) and the infiltration and function of neutrophils in human UC and mouse models, particularly in relation to neutrophil extracellular traps (NETs) and the degranulation processes. APEX1 deficiency resulted in decreased production of the chemokines CXCL1 by the NF-κB pathway in epithelium cells, leading to reduced accumulation and activation of neutrophils associated with colitis in colon tissue, as well as decreased levels of IL-1β. Furthermore, APEX1 deficiency reduced symptoms of colitis by decreasing epithelial cell apoptosis and altering the gut microbiome. Studies related to the redox activity of APEX1 have shown that the combination of the redox inhibitor E3330 with 5-aminosalicylic acid (5-ASA) can effectively alleviate colitis, indicating that APEX1 has promising prospects for clinical treatment of IBD. APEX1 is required for interactions between neutrophil and intestinal epithelial cells. This study provided a mechanism demonstrating that APEX1 protein triggered the risk of UC by promoting neutrophil infiltration and compromising intestinal epithelial barrier function.

Neutrophil Extracellular Traps Promote Polyploidization of Tubular Epithelial Cells after Kidney Injury

Neutrophil Extracellular Traps Promote Polyploidization of Tubular Epithelial Cells after Kidney Injury

Paracetamol suppresses neutrophilic oxygen radicals through competitive inhibition and scavenging

Neutrophils, pivotal cells of innate and adaptive immune responses, employ reactive oxygen species (ROS) to combat pathogens and control gene expression. Paracetamol (acetaminophen) is widely used as an analgesic and antipyretic medication, yet its precise mechanisms of action are not yet fully understood. Here, we investigate the impact of both ingested and in-vitro paracetamol on neutrophil ROS activity, using flow cytometry and antioxidant assays. Our studies reveal that paracetamol significantly suppresses ROS activity ex-vivo in the short term. Additionally, both paracetamol and its metabolite N-acetyl-p-benzoquinone imine exhibited direct in vitro antioxidant effects, and paracetamol suppressed neutrophil extracellular trap formation ex vivo. These findings suggest a connection between paracetamol use and altered neutrophil responses, with potential implications for use in some patient groups, such as immunocompromised individuals. Further investigation into paracetamol's effects on neutrophil antimicrobial functions is warranted to elucidate possible risks, particularly when taken frequently or in conjunction with other treatments such as vaccinations.

Immunohistochemical expression of netosis markers (MPO, H2A, H2B) in placenta of RPL women in Basrah Province

Background. Recurrent Pregnancy Loss (RPL) is a multifactorial disorder significantly impacting women’s health globally. Emerging research has implicated Neutrophil Extracellular Traps (NETs) in the pathophysi­ology of RPL, suggesting an immunological underpinning to miscarriage occurrences. Aim. The study aim to evaluate the role and expression of NETosis markers (MPO, histones H2A, H2B) in women with RPL in comparison to pregnant women. Methods. This prospective cohort study, conducted from January 2022 to July 2023, included 30 participants (20 RPL patients and 10 controls) from Al Basrah Maternity and Child Hospital. Immunohistochemical technique were employed to detect Myeloperoxidase and histones in placental samples. Statistical analysis was performed using SPSS, with significance set at p&lt;90.05. Results. Immunohistochemical analysis of placental tissues indicated significant overexpression of Myelo­peroxidase (MPO), and histones H2A and H2B, in RPL patients compared to control, emphasizing the potential involvement of NETs in placental pathology associated with miscarriage. The expression levels of MPO were positive in 80% of RPL patients but undetected in control (p = 0.0001). Histone expressions also differed significantly, with H2A detected in 55% of RPL patients compared to none in control (p = 0.001) and H2B in 70% versus 30% (both p &lt;0.001).

Peripheral blood transcriptome analysis in sepsis-associated acute kidney injury

Sepsis-associated acute kidney injury (S-AKI) presents significant clinical challenges, necessitating deeper insights into its molecular mechanisms. We conducted a comprehensive analysis—including Principal Component Analysis (PCA), differential gene expression, KEGG pathway enrichment, and Gene Set Enrichment Analysis (GSEA)—to elucidate the underlying pathways involved in S-AKI. PCA revealed distinct clustering between S-AKI patients and controls, with differential gene expression identifying 1,759 significant genes (912 upregulated, 847 downregulated). Notable upregulated genes included CYP19A1 and LY6G6F, while downregulated genes encompassed LRP1B and SIGLEC8. KEGG analysis highlighted pathways related to adaptive immune responses and infection, such as “Th1 and Th2 cell differentiation" and "Primary immunodeficiency.” GSEA pinpointed "Neutrophil extracellular trap formation" as the most significantly enriched pathway, underscoring neutrophil-mediated responses in S-AKI. Our findings suggest potential molecular targets for diagnosis and therapeutic intervention, providing a foundation for future research and improved clinical outcomes.

Association of corticosteroid therapy with reduced acute kidney injury and lower NET markers in severe COVID-19: an observational study

BackgroundAcute kidney injury (AKI) is common in critical cases of coronavirus disease 2019 (COVID-19) and associated with worse outcome. Dysregulated neutrophil extracellular trap (NET) formation is one of several suggested pathophysiological mechanisms involved in the development of COVID-19 associated AKI. The corticosteroid dexamethasone was implemented as a standard treatment for severe COVID-19 as of June 2020. A sub-analysis of a prospective observational single center study was performed to evaluate the effect of corticosteroid treatment on AKI development and NET markers in critical cases of COVID-19.ResultsTwo hundred and ten adult patients admitted to intensive care at a tertiary level hospital due to respiratory failure or shock secondary to SARS-CoV-2-infection between March 13th 2020 and January 14th 2021 were included in the study. Ninety-seven of those did not receive corticosteroids. One hundred and thirteen patients were treated with corticosteroids [dexamethasone (n = 98) or equivalent treatment (n = 15)], but the incidence of AKI was assessed only in patients that received corticosteroids before any registered renal dysfunction (n = 63). Corticosteroids were associated with a lower incidence of AKI (19% vs 55.8%, p < 0.001). Fewer patients demonstrated detectable concentrations of extracellular histones in plasma when treated with corticosteroids (8.7% vs 43.1%; p < 0.001). Extracellular histones and in particular non-proteolyzed histones were observed more frequently with increasing AKI severity (p < 0.001). MPO-DNA was found in lower concentrations in patients that received corticosteroids before established renal dysfunction (p = 0.03) and was found in higher concentrations in patients with AKI stage 3 (p = 0.03). Corticosteroids did not ameliorate established AKI during the first week of treatment.ConclusionCorticosteroid treatment in severe COVID-19 is associated with a lower incidence of AKI and reduced concentrations of NET markers in plasma.