Search Results (162)

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

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

(6S,9R)-vomifoliol (VO) is a natural norisoprenoid of the megastigmane type derived from Gaultheria procumbens, an aromatic, evergreen shrub whose leaves, fruits, and aerial parts are used in traditional phytotherapy to treat oxidative stress and inflammation-related disorders. The plant is known as a rich source of essential oil and polyphenols. However, the levels of other constituents of G. procumbens, including VO, have yet to be explored. There is also a knowledge gap in the pharmacological potential of VO in the context of inflammation. Therefore, the present study aimed to investigate the accumulation of VO in leaves, stems, and fruits of G. procumbens and to determine its antioxidant and anti-inflammatory effects in non-cellular in vitro and cell-based models of human immune cells ex vivo. The GC-FID-MS (gas chromatography coupled with flame ionisation detector and mass spectrometer) analysis revealed the leaves as the richest source of VO (0.36 mg/g dw of the plant material) compared to other G. procumbens organs. In non-cellular activity tests, VO showed comparable to positive control anti-inflammatory activity against lipoxygenase, with significantly weaker impact on hyaluronidase and cyclooxygenase-2, and no effect on cyclooxygenase-1 isozyme. VO at 5–75 μM revealed a significant and dose-dependent ability to reduce the reactive oxygen species (ROS) level, downregulate the release of pro-inflammatory cytokines [tumour necrosis factor-α (TNF-α), interleukin-8 (IL-8), IL-6, and IL-1β] and tissue-remodelling enzymes (elastase-2, metalloproteinase-9), and up-regulate the secretion of anti-inflammatory cytokine IL-10 in bacterial lipopolysaccharide (LPS)- and N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-stimulated human neutrophils and peripheral blood mononuclear cells (PBMCs) ex vivo. Furthermore, a significant reduction in IL-6, lipoxygenase (LOX), nuclear factor κ-light-chain-enhancer of activated B cells 1 (NF-κB1), and NF-κB2 gene expression in LPS-stimulated peripheral blood lymphocytes was demonstrated by real-time PCR. The cellular safety of VO at 5–75 μM was confirmed by flow cytometry, with the viability of neutrophils and PBMCs after incubation with VO at 93.8–98.4%. The results encourage further studies of VO as a promising non-cytotoxic natural anti-inflammatory agent and support the use of leaves of G. procumbens in the adjuvant treatment of oxidative stress and inflammation-related diseases of affluence. Full article

Vanillic acid (VA) is a dietary benzoic acid derivative, flavoring agent, and food stabilizer. In this study, the antioxidant and anti-inflammatory potential of VA was explored in vitro and ex vivo in human immune cells and non-cellular models. In neutrophils, VA significantly downregulated the fMLP-induced oxidative burst and the generation of reactive oxygen species (ROS); it also suppressed the release of pro-inflammatory cytokines (TNF-α, IL-8) and the tissue-remodeling enzyme elastase-2 (ELA-2) in cells stimulated with LPS and fMLP+cytochalasin B. Additionally, VA showed good biocompatibility with human neutrophils and peripheral blood mononuclear cells (PBMCs) across the tested concentrations of 1–50 µg/mL. Furthermore, VA at 1–5 μg/mL enhanced the non-enzymatic antioxidant capacity of human plasma (NEAC) and prevented oxidative and nitrative damage to plasma proteins by protecting tyrosine moieties and thiols from peroxynitrite. VA also inhibited lipid peroxidation and the formation of thiobarbituric acid-reactive substances (at 50 μg/mL) and protein-bound carbonyls (at 5–50 μg/mL) in peroxynitrite-treated plasma. In non-cellular tests, VA acted as a hypochlorous acid and hydrogen peroxide scavenger and inhibited non-enzymatic protein glycation, outperforming the references Trolox and aminoguanidine. Along with existing data from animal models and studies on polyphenol intake, these results might support the synergic role of VA in dietary protection against chronic diseases related to oxidative stress and inflammation. Full article

Reactive oxygen species (ROS), commonly recognized as free radicals, significantly contribute to skin damage by disrupting defense and repair mechanisms, thereby accelerating the aging process. An effective strategy to prevent and alleviate skin aging involves the application of topical formulations enriched with powerful antioxidant compounds. Sacha inchi oil (Plukenetia volubilis L.) has been reported to possess significant antioxidant activity, while its oil contains a high content of omega-3 fatty acids, offering potential anti-aging benefits. This study aims to evaluate the stability, in vitro anti-aging activity, and skin irritation assessments of a facial serum containing Sacha inchi oil (SIO) formulated as a topical anti-aging agent. The stability of the serum was assessed by analyzing its organoleptic properties, homogeneity, viscosity, spreadability, pH, microbial contamination, and heavy metal content over a three-month period under controlled climatic conditions. The in vitro anti-aging activity was evaluated through enzyme inhibition assays for neutrophil elastase and collagenase, while skin irritation was assessed via human patch testing. The results indicated that the SIO facial serum exhibits excellent stability, significant anti-aging activity, and is safe for topical application, with no irritant effects observed during skin irritation assessments. Full article

Neutrophil elastase (NE) has been reported to be a pro-inflammatory stimulus for macrophages. The aim of the present study was to determine the impact of NE exposure on the human macrophage proteome and evaluate its impact on pro-inflammatory signals. Human blood monocytes from healthy volunteers were differentiated to macrophages and then exposed to either 500 nM of NE or control vehicle for 2 h in triplicate. Label-free quantitative proteomics analysis identified 41 differentially expressed proteins in the NE versus control vehicle datasets. A total of 26 proteins were downregulated and of those, 21 were cell surface proteins. Importantly, four of the cell surface proteins were proteoglycans: neuropilin 1 (NRP1), syndecan 2 (SDC2), glypican 4 (GPC4), and CD99 antigen-like protein 2 (CD99L2) along with neuropilin 2 (NRP2), CD99 antigen (CD99), and endoglin (ENG) which are known interactors. Additional NE-targeted proteins related to macrophage function were also measured including CD40, CD48, SPINT1, ST14, and MSR1. Collectively, this study provides a comprehensive unbiased view of selective NE-targeted cell surface proteins in chronically inflamed lungs. Full article

Elevated protease activity is a hallmark of non-healing chronic wounds. Though multiple biomaterials exist that are successful in treating wounds, their roles in modulating the enzymatic environment of the wound are only beginning to be elucidated. Because keratin has long been known to be resistant to degradation by most enzymes, we studied a keratin biomaterial, the human keratin matrix (HKM), in the presence of enzymes identified to contribute to wound chronicity: neutrophil-derived elastase (NE), matrix metalloproteinase 1 (MMP-1), and MMP-9. Upon finding the suppression of MMP-9 activity in the presence of HKM without reducing enzyme protein levels, we further studied the ability of HKM to bind metal ions in the wound and showed the reduction of Zn²⁺ ion concentration in the presence of HKM. Finally, because of the enzyme resistance of keratin and the suppression of wound enzymes, we demonstrated that HKM was durable in the wound environment, and did not degrade in wound healing efficacy when left in place for two weeks compared to one week in a diabetic mouse model of wound non-healing. In this way, we show HKM is a unique and effective biomaterial for the treatment of chronic wounds through the modulation of wound MMP activity. Full article

Enhancing or protecting sperm motility has always been a pivotal approach to improving the ewe pregnancy rate. Sperm motility is highly susceptible to the immune status of the reproductive tract. Neutrophil extracellular traps (NETs) have been demonstrated to capture sperm and impair its motility in human, swine, and goat species. Quercetin is a flavonoid derived from Cuscuta Chinensis Lam., which can protect sperm from oxidative damage. In this study, we investigated whether inflammation decreases sperm motility and tried to clarify the potential protective mechanism of quercetin on goat sperm motility. Sperm-triggered NETs were analyzed by immunofluorescence analysis. Sperm acrosome integrity was detected by using giemsa staining. Quercetin exhibited no cytotoxicity towards sperm and PMNs within the concentration range of 20–80 μM. PMNs impaired both the survival rate and rapid linear motility of sperm, while quercetin significantly enhanced these parameters. PMNs captured sperm through NETs composed of DNA, citrullinated histone 3 (citH3), and neutrophil elastase (NE); however, quercetin effectively inhibited the release of sperm-stimulated NETs. The stimulation of PMNs with sperm resulted in a significant increase in levels of ROS and MDA, which decreased by quercetin. Moreover, PMNs caused integrity violation to both the plasma membrane and acrosome in sperm; this effect was significantly alleviated by quercetin. In conclusion, quercetin effectively ameliorated PMN-reduced sperm motility through the inhibition of NETs and oxidative stress, and preserving sperm plasma membrane and acrosome integrity, thereby providing preliminary insights into the underlying mechanisms and theoretical support for the development of potential sperm protectors. Full article

The collaboration between cellular proteases and host cells is pivotal in mounting an effective innate immune defense. Of particular interest is the synergistic interaction between cathepsin G (CatG) and neutrophil elastase (NE), which are proteases secreted by activated neutrophils, and the human alveolar basal epithelial cell line (A549) and the human lung epithelial-like cell line (H1299), because of the potential implications for viral infection. Our study aimed to investigate the binding capacity of CatG and NE on the surface of A549 and H1299 cells through preincubation with purified CatG and NE; thereby, the proteolytic activity could be detected using activity-based probes. Both CatG and NE were capable of binding to the cell surface and exhibited proteolytic activity, leading to increased cell surface levels of MHC I molecules, which is crucial for displaying the endogenous antigenic repertoire. In addition, CatG cleaved the S2′ site of the SARS-CoV-2 spike protein at two specific sites (₈₁₅RS₈₁₆ and ₈₁₇FI₈₁₈) as well as NE (₈₁₃SK₈₁₄ and ₈₁₈IE₈₁₉), which potentially leads to the destruction of the fusion peptide. Additionally, furin required the presence of Ca²⁺ ions for the distinct cleavage site necessary to generate the fusion peptide. Overall, the findings suggest that CatG and NE can fortify target cells against viral entry, underscoring the potential significance of cell surface proteases in protecting against viral invasion. Full article

Neutrophil elastase (HNE), like other members of the so-called GASPIDs (Granule-Associated Serine Peptidases of Immune Defense), is activated during protein biosynthesis in myeloid precursors and stored enzymatically active in cytoplasmic granules of resting neutrophils until secreted at sites of host defense and inflammation. Inhibitors thus could bind to the fully formed active site of the protease intracellularly in immature progenitors, in circulating neutrophils, or to HNE secreted into the extracellular space. Here, we have compared the ability of a panel of diverse inhibitors to inhibit HNE in the U937 progenitor cell line, in human blood-derived neutrophils, and in solution. Most synthetic inhibitors and, surprisingly, even a small naturally occurring proteinaceous inhibitor inhibit HNE intracellularly, but the extent and dynamics differ markedly from classical enzyme kinetics describing extracellular inhibition. Intracellular inhibition of HNE potentially affects neutrophil functions and has side effects, but it avoids competition of inhibitors with extracellular substrates that limit its efficacy. As both intra- and extracellular inhibition have advantages and disadvantages, the quantification of intracellular inhibition, in addition to classical enzyme kinetics, will aid the design of novel, clinically applicable HNE inhibitors with targeted sites of action. Full article

In diabetic ulcers, an increased secretion of human neutrophil elastase (HNE) and bacterial infections play crucial roles in hindering healing. Considering that, the present study proposed the development of multi-action polycaprolactone (PCL)/polyethylene glycol (PEG) electrospun fibers incorporating elastase-targeting peptides, AAPV and WAAPV, via blending. Characterization confirmed WAAPV’s efficacy in regulating proteolytic enzymes by inhibiting HNE. The engineered fibers, particularly those containing PEG, exhibited optimal wettability but an accelerated degradation that was mitigated with the peptide’s inclusion, thus promoting a sustained peptide release over 24 h. Peptide loading was verified indirectly through thermal stability and hydration capacity studies (hydrophobic bonding between PCL and WAAPV and hydrophilic affinities between PCL/PEG and AAPV) and determined at ≈51.1 µg/cm² and ≈46.0 µg/cm² for AAPV and ≈48.5 µg/cm² and ≈51.3 µg/cm² for WAAPV, respectively, for PCL and PCL/PEG. Both AAPV and WAAPV effectively inhibited HNE, with PEG potentially enhancing this effect by interacting with the peptides and generating detectable peptide–PEG complexes (≈10% inhibition with PCL + peptide fibers after 6 h of incubation, and ≈20% with PCL/PEG + peptide fibers after 4 h incubation). Peptide-loaded fibers demonstrated antibacterial efficacy against Staphylococcus aureus (up to ≈78% inhibition) and Escherichia coli (up to ≈66% inhibition), with peak effectiveness observed after 4 and 2 h of incubation, respectively. This study provides initial insights into the WAAPV’s potential for inhibiting HNE and bacteria activities, showing promise for applications in diabetic ulcer management. Full article

Human immunodeficiency virus (HIV) and malaria, caused by infection with Plasmodium spp., are endemic in similar geographical locations. As a result, there is high potential for HIV/Plasmodium co-infection, which increases the pathology of both diseases. However, the immunological mechanisms underlying the exacerbated disease pathology observed in co-infected individuals are poorly understood. Moreover, there is limited data available on the impact of Plasmodium co-infection on antiretroviral (ART)-treated HIV infection. Here, we used the rhesus macaque (RM) model to conduct a pilot study to establish a model of Plasmodium fragile co-infection during ART-treated simian immunodeficiency virus (SIV) infection, and to begin to characterize the immunopathogenic effect of co-infection in the context of ART. We observed that P. fragile co-infection resulted in parasitemia and anemia, as well as persistently detectable viral loads (VLs) and decreased absolute CD4+ T-cell counts despite daily ART treatment. Notably, P. fragile co-infection was associated with increased levels of inflammatory cytokines, including monocyte chemoattractant protein 1 (MCP-1). P. fragile co-infection was also associated with increased levels of neutrophil elastase, a plasma marker of neutrophil extracellular trap (NET) formation, but significant decreases in markers of neutrophil degranulation, potentially indicating a shift in the neutrophil functionality during co-infection. Finally, we characterized the levels of plasma markers of gastrointestinal (GI) barrier permeability and microbial translocation and observed significant correlations between indicators of GI dysfunction, clinical markers of SIV and Plasmodium infection, and neutrophil frequency and function. Taken together, these pilot data verify the utility of using the RM model to examine ART-treated SIV/P. fragile co-infection, and indicate that neutrophil-driven inflammation and GI dysfunction may underlie heightened SIV/P. fragile co-infection pathogenesis. Full article

Serine protease inhibitors are a superfamily of proteins that regulate various physiological processes including fibrinolysis, inflammation and immune responses. In parasite systems, serpins are believed to play important roles in parasite colonization, inhibition of host immune serine proteases and penetration of defensive barriers. However, serpins are less well characterized in schistosomes. In this study, a Schistosoma mansoni serpin (Smserpin-p46) containing a 1360 base pair open reading frame, was cloned, expressed and functionally characterized. Bioinformatics analysis revealed that Smserpin-p46 contains the key residues, structural domains and motifs characteristic of inhibitory serpins. Gene expression profiling demonstrated stage-specific expression of Smserpin-p46 with the highest expression in adult male worms. Recombinant Smserpin-p46 (rSmserpin-p46) inhibited both human neutrophil cathepsin G and elastase, key serine proteases involved in NETosis, a program for the formation of neutrophil extracellular traps. Using specific rabbit antiserum, Smserpin-p46 was detected in soluble worm antigen preparation and was localized to the adult worm tegument. Cumulatively, the expression of Smserpin-p46 on the parasite tegument and its ability to inhibit proteases involved in NETosis highlights the importance of this serpin in parasite-host interactions and encourages its further investigation as a candidate vaccine antigen for the control of schistosomiasis. Full article

Reproductive failure in dogs is often due to unknown causes, and correct diagnosis and treatment are not always achieved. This condition is associated with various congenital and acquired etiologies that develop inflammatory processes, causing an increase in the number of leukocytes within the female reproductive tract (FRT). An encounter between polymorphonuclear neutrophils (PMNs) and infectious agents or inflammation in the FRT could trigger neutrophil extracellular traps (NETs), which are associated with significantly decreased motility and damage to sperm functional parameters in other species, including humans. This study describes the interaction between canine PMNs and spermatozoa and characterizes the release of NETs, in addition to evaluating the consequences of these structures on canine sperm function. To identify and visualize NETs, May–Grünwald Giemsa staining and immunofluorescence for neutrophil elastase (NE) were performed on canine semen samples and sperm/PMN co-cultures. Sperm viability was assessed using SYBR/PI and acrosome integrity was assessed using PNA-FITC/PI by flow cytometry. The results demonstrate NETs release in native semen samples and PMN/sperm co-cultures. In addition, NETs negatively affect canine sperm function parameters. This is the first report on the ability of NETs to efficiently entrap canine spermatozoa, and to provide additional data on the adverse effects of NETs on male gametes. Therefore, NETs formation should be considered in future studies of canine reproductive failure, as these extracellular fibers and NET-derived pro-inflammatory capacities will impede proper oocyte fertilization and embryo implantation. These data will serve as a basis to explain certain reproductive failures of dogs and provide new information about triggers and molecules involved in adverse effects of NETosis for domestic pet animals. Full article

Neutrophil elastase (NE) is taken up by macrophages, retains intracellular protease activity, and induces a pro-inflammatory phenotype. However, the mechanism of NE-induced pro-inflammatory polarization of macrophages is not well understood. We hypothesized that intracellular NE degrades histone deacetylases (HDAC) and Sirtuins, disrupting the balance of lysine acetylation and deacetylation and resulting in nuclear to cytoplasmic translocation of a major alarmin, High Mobility Group Box 1 (HMGB1), a pro-inflammatory response in macrophages. Human blood monocytes were obtained from healthy donors or from subjects with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD). Monocytes were differentiated into blood monocyte derived macrophages (BMDMs) in vitro. Human BMDMs were exposed to NE or control vehicle, and the abundance of HDACs and Sirtuins was determined by Western blotting of total cell lysates or nuclear extracts or determined by ELISA. HDAC, Sirtuin, and Histone acetyltransferase (HAT) activities were measured. NE degraded most HDACs and Sirtuin (Sirt)1, resulting in decreased HDAC and sirtuin activities, with minimal change in HAT activity. We then evaluated whether the NE-induced loss of Sirt activity or loss of HDAC activities would alter the cellular localization of HMGB1. NE treatment or treatment with Trichostatin A (TSA), a global HDAC inhibitor, both increased HMGB1 translocation from the nucleus to the cytoplasm, consistent with HMGB1 activation. NE significantly degraded Class I and II HDAC family members and Sirt 1, which shifted BMDMs to a pro-inflammatory phenotype. Full article