Search Results (342)

Background/Objectives: The quality of clinical studies is largely determined by the bioanalytical methods used for testing study samples. Rigorous assay validation following defined criteria, for example, the European Medicines Agency guideline for bioanalytical method validation, is a prerequisite for such assays. Alpha1-antitrypsin (AAT) measurement, i.e., the specific measurement of AAT protein and its associated elastase-inhibitory activity, is an integral part of assay panels for clinical studies addressing AAT deficiency. Specifically, AAT must be measured in the matrix of citrated human plasma as well as in diluted solutions with high salt concentrations obtained through bronchoalveolar lavage (BAL). Sensitive and selective measurement methods are required, as BAL has a low level of AAT. Methods: We present the validation data obtained for three AAT measurement methods. Two of them, nephelometry and the enzyme-linked immunosorbent assay, which clearly differ in their sensitivity, provide AAT protein concentrations. The third is the highly sensitive, newly developed elastase complex formation immunosorbent assay that specifically measures the inhibitory activity of AAT against its pivotal target, protease neutrophil elastase. Using samples with relevant AAT concentrations, we addressed the assays’ characteristics: accuracy, precision, linearity, selectivity, specificity, limit of quantification and short-term analyte stability Results: Overall, the three methods demonstrated low total errors, a combined measure reflecting accuracy and precision, even at low analyte concentrations of less than 0.5 µg/mL; adequate linearity over the required assay range; and acceptable selectivity and specificity. Furthermore, the short-time stability of the analyte was also demonstrated. Conclusions: All three AAT measurement methods met the acceptance criteria defined by the guidelines on bioanalytical assay validation, qualifying these methods for clinical sample analysis. Full article

Cancer remains a major global health challenge requiring the development of diagnostic and therapeutic strategies. Liquid biopsy is considered a promising minimally invasive tool for cancer screening, prognosis and treatment monitoring. Recent studies suggest that neutrophil extracellular traps (NETs) may also be potential liquid biopsy markers. NETs are web-like chromatin structures released by neutrophils in response to various stimuli to trap and neutralize pathogens. However, excessive or dysregulated NET formation has been implicated in tumor progression and metastasis. Elevated levels of NETs have been observed in patients with various types of cancer and correlate with disease stage and prognosis. The presence of NET markers such as citrullinated histone H3 (H3Cit), neutrophil elastase (NE) and myeloperoxidase (MPO) has been associated with higher tumor burden and poorer clinical outcomes. Several studies have shown a positive correlation between NET markers and circulating free DNA (cfDNA) levels, suggesting that NETs may increase the sensitivity of liquid biopsy in detecting and monitoring cancer progression. This review examines the role of NETs in the tumor microenvironment, their contribution to cancer progression and metastasis, and their potential use in liquid biopsy and cancer therapy. Full article

Sepsis is a clinical syndrome characterized by a dysregulated host response to infection, frequently resulting in septic shock and multi-organ failure. Emerging evidence highlights the critical role of neutrophil extracellular traps (NETs) in the pathophysiology of sepsis. NETs are extracellular structures composed of chromatin DNA, histones, and granular proteins released by neutrophils through a specialized form of cell death known as NETosis. While NETs contribute to the containment of pathogens, their excessive or dysregulated production in sepsis is associated with endothelial damage, immunothrombosis, and organ dysfunction. Several NET-associated biomarkers have been identified, including circulating cell-free DNA (cfDNA), histones, MPO-DNA complexes, and neutrophil elastase–DNA complexes, which correlate with the disease severity and prognosis. Therapeutic strategies targeting NETs are currently under investigation. Inhibition of NET formation using PAD4 inhibitors or ROS scavengers has shown protective effects in preclinical models. Conversely, DNase I therapy facilitates the degradation of extracellular DNA, reducing the NET-related cytotoxicity and thrombotic potential. Additionally, heparin and its derivatives have demonstrated the ability to neutralize NET-associated histones and mitigate coagulopathy. Novel approaches include targeting upstream signaling pathways, such as TLR9 and IL-8/CXCR2, offering further therapeutic promise. Full article

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease predominantly of the small airways and parenchyma. COPD lungs exhibit an influx of circulating innate immune cells, which, when isolated, display impaired functions, including imbalanced protease secretion. In addition to immune cells, the extracellular matrix (ECM) plays a crucial role in COPD pathology. Remodeling of the ECM can generate ECM fragments, which can be released into circulation and subsequently induce pro-inflammatory responses. COPD is a heterogeneous disease, and serological biomarkers can be used to sub-categorize COPD patients for targeted treatments and optimal recruitment in clinical trials. This study evaluated fragments of calprotectin, collagen type VI, and versican, generated by neutrophil elastase and matrix metalloproteinases (MMP-) 2 and 12, respectively, as potential biomarkers of COPD disease, severity, and endotypes. Lower plasma levels of a neoepitope marker of calprotectin, indicative of activated neutrophils (nordicCPa9-HNETM), were detected in COPD donors compared to controls. CPa9-HNE was associated with milder disease, higher degree of air-trapping, and higher serum levels of MMP-2. Deposition of CPa9-HNE levels in lung tissue revealed no differences between groups. Taken together, CPa9-HNE was found to be a potential marker of mild COPD, but further studies are warranted to validate our findings. Full article

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide, primarily driven by chronic airway inflammation due to cigarette smoke exposure. Despite its burden, however, current anti-inflammatory therapies offer limited efficacy in preventing disease progression. Plasminogen activator inhibitor-1 (PAI-1), as a key regulator of fibrinolysis, has recently been implicated in structural airway changes and persistent inflammation in patients with COPD. This study aimed to investigate the ability of the PAI-1 inhibitor TM5441 to attenuate airway inflammation and structural lung damage induced by a cigarette smoke extract (CSE) in a mouse model. Mice received intratracheal CSE or vehicle on days 1, 8, and 15, and were sacrificed on day 22. TM5441 (20 mg/kg) was administered orally from days 1 to 22. The CSE significantly increased the mean linear intercept, destructive index, airway resistance, and reductions in dynamic compliance. The CSE also increased the numbers of neutrophils and macrophages in the bronchoalveolar lavage fluid, systemic PAI-1 activity, and neutrophil elastase mRNA and protein expression in the lungs. TM5441 treatment significantly suppressed these changes without affecting coagulation time. These findings suggest that TM5441 may be a novel therapeutic agent for COPD by targeting PAI-1-mediated airway inflammation and emphysema. Full article

This study systematically investigated the inhibitory mechanism of Arctium lappa L. polyphenols (ALP) against human neutrophil elastase (HNE). Molecular docking techniques were employed to predict the binding patterns and inhibition types between polyphenolic components and HNE, complemented by in vitro enzymatic tests to validate inhibitory efficacy. Combination index (CI) analysis was applied to evaluate synergistic effects. Through preliminary in vitro screening, chlorogenic acid, quercetin, and isochlorogenic acid A were identified as key bioactive constituents. Experimental results demonstrated that the half-inhibitory concentration (IC₅₀) of individual compounds against HNE ranged from 46.4 to 203.3 μM, while ALP extract exhibited dose-dependent inhibition (IC₅₀ = 0.99 mg/mL). Drug combination ratios based on individual IC₅₀ values revealed synergistic effects (CI < 1) in chlorogenic acid-quercetin and isochlorogenic acid A-quercetin combinations, whereas antagonism (CI > 1) was observed in chlorogenic acid-isochlorogenic acid A pairs. The molecular docking results predicted that chlorogenic acid and isochlorogenic acid A competitively occupy the same binding site of the target protein (HNE) to exert inhibitory effects, thereby explaining the antagonism produced by their combination. In contrast, quercetin may inhibit HNE with a binding site different from that of chlorogenic acid or isochlorogenic acid A, which accounts for the observed synergistic effects. This study provides the first systematic elucidation of synergistic mechanisms of ALP as natural HNE inhibitors, providing theoretical foundations for developing novel natural HNE inhibitors with potential applications in acute lung injury, COVID-19-associated inflammatory conditions, and chronic inflammatory diseases. Full article

Peptidylarginine deiminase 4 (PAD4) catalyzes protein citrullination, a post-translational modification implicated in type 1 diabetes mellitus (T1DM). This study examined PAD4 expression and activity in the pancreas of streptozotocin (STZ)-induced diabetic Wistar rats. Animals were divided into three groups: (A) STZ-induced diabetic rats (60 mg/kg, i.p.), (B) non-diabetic controls, and (C) diabetic rats treated with Cl-amidine (5 mg/kg), a pan-PAD inhibitor, from week six post-induction. Analyses included PAD4 mRNA and protein expression, citrullinated histone H3 (CitH3), calcium concentration, and neutrophil elastase activity. Diabetic rats exhibited increased PAD4 expression, CitH3 levels, and NETosis markers, alongside reduced pancreatic calcium, suggesting calcium consumption during PAD4 activation. Cl-amidine treatment attenuated NETosis. These results implicate PAD4 in T1DM pathogenesis via NETosis and support the utility of STZ-induced diabetic rats as a model for PAD4-targeted studies. Cl-amidine may represent a promising therapeutic approach to reduce pancreatic inflammation in T1DM. Full article

EMILIN-1 (Elastin Microfibril Interface Located Protein 1) is an extracellular matrix homotrimeric glycoprotein belonging to the EMILIN/Multimerin family, with both structural and regulatory roles, increasingly recognized for its tumor-suppressive functions. Initially identified for its involvement in elastogenesis and vascular homeostasis, EMILIN-1 has gradually emerged as a key player in cancer biology. It exerts its anti-tumor activity through both direct and indirect mechanisms: by regulating tumor cell proliferation and survival and by modulating lymphangiogenesis and the associated inflammatory microenvironment. At the molecular level, EMILIN-1 inhibits pro-oncogenic signaling pathways, such as ERK/AKT and TGF-β, via its selective interaction with α4/α9 integrins. In the tumor microenvironment, it contributes to tissue homeostasis by restraining aberrant lymphatic vessel formation, a process closely linked to tumor dissemination and immune modulation. Notably, EMILIN-1 expression is frequently reduced or its structure altered by proteolytic degradation in advanced cancers, correlating with disease progression and poor prognosis. This review summarizes the current knowledge on EMILIN-1 in cancer, focusing on its dual function as an active extracellular matrix regulator of intercellular signaling. Particular attention is given to its mechanistic role in the control of cell proliferation, underscoring its potential as a novel biomarker and therapeutic target in oncology. Full article

Background/Objectives: Accurate detection of periprosthetic joint infection (PJI) in patients with inflammatory arthritis (IA), including rheumatoid arthritis (RA), remains challenging due to overlapping inflammatory parameters and the influence of immunosuppressive regimens. Methods: A narrative review was conducted using PubMed/MEDLINE (2010–2025). Search terms included “periprosthetic joint infection”, “inflammatory arthritis”, “rheumatoid arthritis”, “diagnosis”, “biomarkers”, “synovial fluid”, and “immunosuppression”. Eventually, 50 studies were included. Results: IA patients diagnosed with PJI are more frequently younger, female, and present with a higher burden of comorbidities and an increased rate of false-positive histological findings and culture-negative infections. Standard biomarkers, such as serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), as well as synovial fluid white blood cell count and polymorphonuclear leukocyte percentage, have a low to moderate value for diagnosing PJI in patients with IA. Optimal thresholds for these tests differ from those recommended by the Musculoskeletal Infection Society (MSIS). Alpha-defensin has demonstrated superior diagnostic performance among synovial fluid biomarkers included in MSIS criteria. Novel markers, such as serum bactericidal permeability-increasing protein (BPI) and neutrophil elastase-2 (ELA-2), as well as synovial C-reactive protein and calprotectin, along with molecular techniques like polymerase chain reaction (PCR), are showing increasing potential. Conclusions: Disease and treatment-related confounders hinder PJI diagnosis in IA. Adjusted thresholds and IA-specific approaches are needed. Further research should validate emerging biomarkers, among which BPI, ELA-2, and synovial CRP show the greatest diagnostic potential and guide perioperative immunosuppressive strategies. Full article

Neutrophil extracellular traps (NETs) are associated with the extracellular release of nuclear chromatin decorated with cytoplasmic proteins. Excessive release of NETs has been reported in chronic lung diseases, including chronic obstructive pulmonary disease (COPD). However, the role of NETs in the pathogenesis of COPD remains unclear. Peptidylarginine deaminase 4 (PAD4) contributes to NET formation. Therefore, in an elastase (ELS)-induced emphysema mouse model, we examined the role of PAD4 using Padi4 gene knockout (KO) mice. First, we confirmed that ELS induced NET formation in the parenchyma of the lungs. PAD4 deficiency suppressed ELS-induced NET expression and tended to ameliorate the lung tissue injury. The cellular profile of bronchoalveolar lavage fluid (BALF) did not differ between the two groups. Additionally, PAD4 deficiency ameliorated emphysema and apoptosis in lung cells. Finally, we examined the effects of PAD4 on comprehensive gene expression signatures using RNA sequencing. Enrichment analysis of the transcriptomic data revealed that the expression of several genes associated with COPD pathogenesis was altered in the KO mice. Overall, the results suggest that PAD4 deficiency improves NET formation and emphysema in the lungs; this pathway can be a potential therapeutic target for the treatment of COPD. Full article

Currently, there are two major theories regarding the pathogenesis of sepsis: hyperimmune and hypoimmune. The hyperimmune theory suggests that a cytokine storm causes the symptoms of sepsis. On the contrary, the hypoimmune theory suggests that immunosuppression causes the manifestations of sepsis. By conducting a microarray analysis on peripheral leukocytes from patients with sepsis, this study found that hyperactivity of TH17 immunity was noted in sepsis patients. Innate immunity-related genes are significantly upregulated, including CD14, TLR1,2,4,5,8, HSP70, CEBP proteins, AP1 (JUNB and FOSL2), TGFB1, IL6, TGFA, CSF2 receptor, TNFRSF1A, S100A binding proteins, CCR2, FPR2, amyloid proteins, pentraxin, defensins, CLEC5A, whole complement machinery, CPD, NCF, MMP, neutrophil elastase, caspases, IgG and IgA Fc receptors (CD64, CD32), ALOX5, PTGS, LTB4R, LTA4H, and ICAM1. The majority of adaptive immunity genes were downregulated, including MHC-related genes, TCR genes, granzymes/perforin, CD40, CD8, CD3, TCR signaling, BCR signaling, T and B cell-specific transcription factors, NK killer receptors, and TH17 helper-specific transcription factors (STAT3, RORA, and REL), as well as Treg-related genes, including TGFB1, IL15, STAT5B, SMAD2/4, CD36, and thrombospondin. The findings of this study show that Th17 with Treg over-presentation play an important role in the pathophysiology of sepsis. Full article

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterized by the fibrotic thickening of the alveolar walls, resulting in compromised gas exchange, restricted ventilation, and respiratory failure. It has been indicated that elastase inhibitors reduced the severity of IPF by neutralizing excessive elastase levels in the lungs. ShSPI is an elastase inhibitor derived from centipede toxin. The present study evaluates the therapeutic effects of ShSPI in a bleomycin-induced idiopathic pulmonary fibrosis model. According to the results, ShSPI markedly reduced the weight loss, showing the improvement of health status in bleomycin-induced mice. Its robust antifibrotic effects were evidenced by the mitigation of alveolar structural damage, reduction in inflammatory cell infiltration, inhibition of collagen deposition, and suppression of fibrotic nodule formation. ShSPI effectively attenuated inflammatory responses by downregulating pro-inflammatory factors (IL-6, IL-1β, and MCP-1) and upregulating the anti-inflammatory factor interleukin-10 (IL-10). After delivered via inhalation, ShSPI exhibited favorable pharmacokinetic properties. It could be detected at 8 h at doses of 1 mg/kg and achieved maximum plasma concentrations (Cmax) of 188.00 ± 64.40 ng/mL in vivo. At high doses (160 mg/kg), ShSPI maintained a strong safety profile, with no detectable toxicity observed. This feature shows the therapeutic potential of ShSPI in the treatment of idiopathic pulmonary fibrosis and provides valuable evidence for its development as a novel peptide-based therapy. Full article

New roles for immune cells, overcoming the classical cytotoxic response, have been highlighted by growing evidence. The immune cells, such as neutrophils, monocytes/macrophages, and eosinophils, are versatile cells involved in the release of web-like DNA structures called extracellular traps (ETs) which represent a relevant mechanism by which these cells prevent microbes’ dissemination. In this process, many enzymes, such as elastase, myeloperoxidase (MPO), and microbicidal nuclear and granule proteins, which contribute to the clearance of entrapped microorganisms after DNA binding, are involved. However, an overproduction and release of ETs can cause unwanted and dangerous effects in the host, resulting in several pathological manifestations, among which are chronic inflammatory disorders, autoimmune diseases, cancer, and diabetes. In this review, we discuss the release mechanisms and the double-edged sword role of ETs both in physiological and in pathological contexts. In addition, we evaluated some possible strategies to target ETs aimed at either preventing their formation or degrading existing ones. Full article

Background: Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn’s disease (CD), is a chronic inflammatory disorder driven by a complex interplay of immune and proteolytic mechanisms. Neutrophil elastase (NE), released at sites of inflammation, plays a central role by promoting inflammation, degrading the extracellular matrix (ECM), and disturbing intestinal barrier integrity via NF-κB activation and E-cadherin degradation. Elafin, an endogenous NE inhibitor, mitigates proteolytic damage, reinforces the intestinal barrier, and exerts anti-inflammatory effects by suppressing NF-κB and reducing pro-inflammatory cytokines. Since the NE/elafin balance is critical in IBD, assessing their ratio may provide a more precise measure of proteolytic dysregulation. This study aimed to evaluate the diagnostic and prognostic utility of urinary NE, elafin, and their ratio in IBD patients. Methods: Urinary concentrations of NE and elafin were measured by immunoassay in 88 subjects including ulcerative colitis and Crohn’s disease patients and healthy individuals. The diagnostic accuracy of these biomarkers was assessed using receiver operating characteristic (ROC) curve analysis. Results: Urinary NE levels were significantly elevated in both UC and CD patients compared to controls, with a 17-fold increase in the UC patients and a 28-fold increase in the CD patients (p < 0.0001). Elafin levels were also increased in IBD patients. The NE/elafin ratio was significantly increased in both disease groups, with a 4.5-fold increase in the UC and 5.6-fold increase in the CD patients compared to healthy controls. The ROC curve analysis demonstrated that the NE/elafin ratio is the most effective biomarker for distinguishing CD patients from healthy individuals (AUC = 0.896), with a high sensitivity (92.9%) and specificity (69.7%), making it a strong diagnostic tool. NE also showed an excellent diagnostic performance both in CD (AUC = 0.842) and UC (AUC = 0.880). The elafin urinary profile had a high diagnostic value, with a better accuracy in the UC patients (AUC = 0.772) than the CD patients (AUC = 0.674), though it was inferior to NE and NE/elafin. Conclusions: Our findings indicate that urinary NE, elafin, the and NE/elafin ratio have significant diagnostic value in differentiating IBD patients from healthy controls. The NE/elafin ratio and NE proved to be the most reliable urinary biomarkers in both CD and UC diagnosis, with a high predictive value and strong discriminatory power. Full article

Cystic fibrosis (CF) is characterized by chronic respiratory infections and excessive inflammation, driven by both host- and pathogen-derived proteases. The dysregulated activity of proteolytic enzymes such as neutrophil elastase (NE), cathepsin G, and matrix metalloproteases (MMPs) degrades lung tissue, exacerbates airway remodeling, and perpetuates inflammatory cycles. Concurrently, bacterial proteases from pathogens such as Pseudomonas aeruginosa and Staphylococcus aureus contribute to immune evasion and tissue destruction, compounding disease severity. Despite advances in antimicrobial and anti-inflammatory therapies, protease-driven lung damage remains a critical challenge. This review examines the dual role of host and bacterial proteases in CF pathophysiology, highlighting emerging protease-targeted therapies aimed at mitigating lung damage and inflammation. Strategies explored include the inhibition of NE, MMPs, and bacterial proteases, with a focus on innovative therapeutic approaches such as dual-function inhibitors, biologics, and advanced drug delivery systems. By restoring the protease–antiprotease balance, these interventions offer the potential to improve clinical outcomes and quality of life for CF patients. Full article