Search Results (141)

Atopic dermatitis is a chronic inflammatory skin disorder characterized by persistent inflammation and severe pruritus. Current anti-inflammatory agents carry risks of long-term adverse effects, while antihistamines provide limited relief of pruritus. Protease-activated receptor 2 (PAR2) has emerged as a critical mediator of both inflammation and pruritus, representing a promising therapeutic target. In this study, we investigated the therapeutic potential of punicalagin (PCG), a potent PAR2 antagonist, in atopic dermatitis. PCG fully and potently inhibited trypsin-induced PAR2 activation in HaCaT cells with an IC₅₀ of 1.30 µM, exhibiting over 40-fold greater selectivity over PAR1. PCG significantly inhibited PAR2-induced phosphorylation of ERK1/2 and NF-κB in both HaCaT and human dermal fibroblast cells and reduced IL-8 secretion in HaCaT cells. In addition, PCG did not significantly affect other pruritus-related GPCRs including H1R, H4R, TGR5, 5HT2A, 5HT2B, and MRGPRX2 at 30 µM. Notably, PCG strongly blocked PAR2-AP-induced scratching in mice. In addition, PCG improved skin lesions, reduced dermatitis severity scores, and alleviated scratching behavior in a DNFB-induced atopic dermatitis model. These effects were associated with reduced epidermal thickness, decreased serum TSLP levels, and inhibition of PAR2-dependent calcium signaling in dorsal root ganglion neurons. These findings demonstrate that PCG is a selective PAR2 antagonist that effectively alleviates both inflammatory and pruritic symptoms of atopic dermatitis, suggesting its potential as a novel therapeutic agent. Full article

Chronic inflammatory conditions often involve the dysregulation of key enzymes, including serine proteases such as transmembrane serine protease 2 (TMPRSS2) and the angiotensin converting enzyme 2 (ACE2), which are key proteins implicated in the cellular entry mechanism of SARS-CoV-2. It remains uncertain whether the gastrointestinal symptoms observed in COVID-19 patients result from direct viral infection of the gastrointestinal tract, a process that may be exacerbated by altered expression of ACE2 or TMPRSS2. In this review, we explore the interplay among ACE2 and TMPRSS2 in the context of inflammatory bowel disease (IBD), including their roles in disease pathology and response to therapy. We also examine methodological approaches for assessing whether protease alterations contribute to increased susceptibility to infection, considering that TMPRSS2 exists in inactive (zymogen) and active forms. Furthermore, while membrane-bound ACE2 facilitates viral entry, soluble ACE2 fragments may act as decoys, preventing virus–receptor interaction. Therefore, the interpretation of changes in full-length versus cleaved forms of ACE2 and related enzymes is critical for understanding vulnerability to SARS-CoV-2 infection. Full article

Luteolin is a natural flavonoid compound with multifaceted pharmacological properties, including anti-oxidant, anti-inflammatory, antiviral, and anti-tumor activities. Network pharmacology analysis has been utilized to decipher the underlying mechanisms and multitargets of luteolin against coronavirus disease 2019 (COVID-19). This review aims to provide a systematic and comprehensive summary of luteolin, as a potential novel remedy with anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) activity, as well as its anti-oxidant mechanisms. We systematically delineate the epidemiological profile, genomic architecture, and replicative dynamics of SARS-CoV-2, thereby constructing a multiscale framework to decode its pathogenic mechanisms. Employing a multi-level network pharmacology analytical strategy, we identify 46 core targets through protein interaction network construction, followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis. Molecular investigations reveal luteolin’s dual antiviral mechanisms, including direct targeting of SARS-CoV-2 proteins and host-directed intervention through suppression of angiotensin-converting enzyme 2 receptor engagement/transmembrane protease serine 2-mediated viral priming. The polypharmacological profile of luteolin demonstrates synergistic effects in blocking viral entry, replication, and host inflammatory cascades. This phytochemical repurposing study of luteolin provides a novel mechanistic paradigm for developing multitarget antiviral agents, highlighting the translational value of natural compounds in combating emerging viral variants. Full article

Microglia, the brain’s resident innate immune cells, play a fundamental role in maintaining neural homeostasis and mediating responses to injury or infection. Upon activation, microglia undergo morphological and functional changes, including phenotypic switching between pro- and anti-inflammatory types and the release of different inflammatory mediators. These processes contribute to neuroprotection and the pathogenesis of various central nervous system (CNS) disorders. Mast cells, although sparsely located in the brain, exert a significant influence on neuroinflammation through their interactions with microglia. Through degranulation and secretion of different mediators, mast cells disrupt the blood–brain barrier and modulate microglial responses, including alteration of microglial phenotypes. Notably, mast cell-derived factors, such as histamine, interleukins, and tryptase, activate microglia through various pathways including protease-activated receptor 2 and purinergic receptors. These interactions amplify inflammatory cascades via various signaling pathways. Previous studies have revealed an exceedingly complex crosstalk between mast cells and microglia suggesting a bidirectional regulation of CNS immunity, implicating their cooperation in both neurodegenerative progression and repair mechanisms. Here, we review some of the diverse communication pathways involved in this complex interplay. Understanding this crosstalk may offer novel insights into the cellular dynamics of neuroinflammation and highlight potential therapeutic targets for a variety of CNS disorders. Full article

Metabolic dysfunction-associated steatotic liver disease (MASLD) has recently become the leading cause of chronic liver disease and can progress to hepatocellular carcinoma (HCC) through multiple pathogenic mechanisms. Protease-activated receptor 2 (PAR2) is a G-protein-coupled receptor activated by proteases such as trypsin, tryptase or coagulation factors VII and Xa. Recent studies have shown that PAR2 expression is increased in the liver of patients with MASLD or liver fibrosis. Its activation is linked to metabolic dysfunction through several pathways, including SREBP1c activation, AMPK inhibition and Akt-induced insulin resistance. Inhibition of PAR2 has been effective in reducing MASLD progression in different animal models. Notably, PAR2 blockade has also been effective in more advanced stages of the disease by dampening chronic inflammation and fibrogenesis through the inhibition of hepatic stellate cell activation and of TGF-β and SerpinB3 production. PAR2 also plays a role in cancer development, promoting tumour proliferation, angiogenesis and expression of immune checkpoint inhibitors (like PD-L1, CD47 and CD24). Due to its multifaceted involvement in liver disease, PAR2 is emerging as a key therapeutic target in this clinical context. This review aims to summarise current knowledge on PAR2′s role in MASLD and its potential as a therapeutic target. Full article

Angiotensin-converting enzyme 2 (ACE2) is a cell-surface receptor that helps the body regulate blood pressure and endocrine secretions. Transmembrane serine protease 2 (TMPRSS2) is a cell surface protein expressed mainly by endothelial cells of the respiratory and digestive tract, which participates in the cleavage of protein peptide bonds with serine as the active site. These two proteins have been studied to be highly associated with infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Soybean trypsin inhibitor (SBTI) has special bioactivities such as anticarcinogenic and anti-inflammatory functions, which can be widely used in functional foods or drugs. Our study involved in vitro and in vivo experiments to elucidate the effect of SBTI on SARS-CoV-2 host invasion. First, it was confirmed that being under 250 μg/mL of SBTI was not toxic to HepG2, HEK293T, and Calu-3 cells. The animal study administered SBTI to mice once daily for 14 days. In the lungs, liver, and kidneys, the histopathologic findings of the SBTI group were not different from those of the control group, but the expression of ACE2, TMPRSS2, and CD147 was reduced. Thus, our findings suggest that the inhibition of ACE2, TMPRSS,2 and CD147 proteins by SBTI shows promise in potentially inhibiting SARS-CoV-2 infection. Full article

We aimed to examine the effect of zonulin and zonulin inhibition on gastrointestinal (GI) motility and the mRNA expression of zonulin and the protease-activated receptor 2 (par2), the primary receptor for zonulin, under conditions of inflammation by lipopolysaccharide (LPS) injection. The experimental models included zonulin transgenic mice (ztm), par2 knockout ztm (ztm-par2 −/−), ztm exposed to the zonulin inhibitor AT1001 (ztm-AT1001), and wildtype mouse controls. GI transit was measured by fluorescein isothiocyanate-dextran and mRNA expression by real-time quantitative polymerase chain reaction in whole, and in epithelial and non-epithelial tissues of all GI segments. There were no differences in the GI transit between mouse groups at baseline. After the LPS injection, ztm mice had an attenuated slowing of the GI transit compared to wildtype mice. The zonulin-inhibited mice had motility patterns similar to wildtype mice. zonulin upregulation was noted in GI segments of the ztm, ztm-par2 −/−, and ztm-AT1001 after the LPS injection. Differences in motility patterns between ztm and zonulin inhibition models despite zonulin expression in GI segments of all mouse groups supports that PAR2 is key for zonulin’s effect on motility under conditions of inflammation. However, the findings from the epithelial and non-epithelial compartments suggest that the pathway of activity is complex and likely indirect. Full article

Background: Alpha-1 antitrypsin (AAT) is a multifunctional protease inhibitor that has been shown to have anti-inflammatory properties in various diseases. AAT has been reported to protect against renal injury via anti-apoptotic, anti-fibrotic, and anti-inflammatory effects. However, its role in mitigating renal inflammation and reducing high blood pressure induced by salt-loading has never been studied. Methods: In this study, we salt-loaded 129Sv mice to induce hypertension and then administered purified human AAT (hAAT) or the vehicle to investigate whether renal inflammation and associated inflammatory/signaling pathways are mitigated. Results: Western blotting and densitometric analysis showed administration of hAAT attenuated protein expression of kidney injury molecule-1 (KIM1), CD93, CD36, and the toll-like receptor 2 and 4 (TLR-2/4) in kidney lysates. Similarly, protein expression of two key inflammatory transcription factors, signal transducer and activator of transcription 3 (STAT3) and NF-Kappa B were shown to be attenuated in the kidneys of 129Sv mice that received hAAT. Conversely, hAAT treatment upregulated the expression of heat shock protein 70 (HSP70) and immunohistochemistry confirmed these findings. Conclusions: Purified hAAT administration may be efficacious in mitigating renal inflammation associated with the development of hypertension from salt-loading, potentially through a mechanism involving the reduction of pro-inflammatory and injury-associated proteins. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, remains a major global health threat. The virus enters host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor. Several small-molecule antiviral drugs, including molnupiravir, favipiravir, remdesivir, and nirmatrelvir have been shown to inhibit SARS-CoV-2 replication and are approved for treating SARS-CoV-2 infections. Nirmatrelvir inhibits the viral main protease (M^pro), a key enzyme for processing polyproteins in viral replication. In contrast, molnupiravir, favipiravir, and remdesivir are prodrugs that target RNA-dependent RNA polymerase (RdRp), which is crucial for genome replication and subgenomic RNA production. However, undergoing extensive metabolism profoundly impacts their therapeutic effects. Carboxylesterases (CES) are a family of enzymes that play an essential role in the metabolism of many drugs, especially prodrugs that require activation through hydrolysis. Molnupiravir is activated by carboxylesterase-2 (CES2), while remdesivir is hydrolytically activated by CES1 but inhibits CES2. Nirmatrelvir and remdesivir are oxidized by the same cytochrome P450 (CYP) enzyme. Additionally, various transporters are involved in the uptake or efflux of these drugs and/or their metabolites. It is well established that drug-metabolizing enzymes and transporters are differentially expressed depending on the cell type, and these genes exhibit significant polymorphisms. In this review, we examine how CES-related cellular and genetic factors influence the therapeutic activities of these widely used COVID-19 medications. This article highlights implications for improving product design, targeted inhibition, and personalized medicine by exploring genetic variations and their impact on drug metabolism and efficacy. Full article

This study investigated the effects of potassium magnesium sulfate (PMS) on intestinal dissociation and absorption rate, immune function, and expression of the NOD-like receptor thermal domain-associated protein 3 (NLRP3) inflammasome, aquaporins (AQPs), and potassium and magnesium ion channels in weaned piglets. Experiment 1 involved the assessment of the dissociation rate of PMS in pig digestive fluid and the absorption rate of PMS in the small intestine using an Ussing chamber in vitro. In Experiment 2, 216 healthy 21-day-old weaned piglets were selected and randomly assigned to six groups (0%, 0.15%, 0.30%, 0.45%, 0.60%, and 0.75% PMS), with each group 6 replicates of six piglets per replicate. The in vitro Ussing chamber results indicated that the absorption of K⁺ and Mg²⁺ in the jejunum and ileum was significantly higher than that in the duodenum (p < 0.05). The in vivo study demonstrated that the addition of PMS resulted in a linear increase in serum K⁺, IgG, and interleukin (IL)-2 levels while simultaneously reducing serum IL-1β levels (p < 0.05). Dietary PMS significantly elevated serum IL-10 and Mg²⁺ levels in feces (p < 0.05). Furthermore, supplementation with 0.60% or 0.75% PMS significantly downregulated the mRNA expression of NLRP3 in the jejunum (p < 0.05). Dietary PMS supplementation linearly reduced the mRNA expression levels of cysteine protease 1 (Caspase-1) and IL-1β in both the jejunum and colon as well as the mRNA expression levels of two-pore domain channel subfamily K member 5 (KCNK5) in these regions (p < 0.05). Notably, supplementation with 0.15% PMS significantly decreased the mRNA expression of transient receptor potential channel 6 (TRPM6) in the jejunum and significantly increased the expression of TRPM6 in the colon (p < 0.05). Dietary addition of 0.45% and 0.60% PMS significantly increased the mRNA expression of aquaporin 3 (AQP3) in the colon (p < 0.05), whereas 0.75% PMS significantly increased the mRNA expression of aquaporin 8 (AQP8) in both the jejunum and colon. Moreover, the expression levels of AQP3 and AQP8 were significantly negatively correlated with the diarrhea rate observed between days 29 and 42. In conclusion, dietary PMS supplementation improved immune function, inhibited the activation of intestinal NLRP3, and modulated the expression of water and ion channels in weaned piglets, thereby contributing to the maintenance of intestinal water and ion homeostasis, which could potentially alleviate post-weaning diarrhea in piglets. The recommended supplemental level of PMS in the corn-soybean basal diet for weaned piglets is 0.30%. Full article

Background: Anti-PAR 1 (protease-activated receptor 1) and anti-ACE 2 (angiotensin 2-converting enzyme 2) antibodies are a kind of non-HLA (human leukocyte antigens) antibodies postulated to be of significance in autoimmunological diseases and organ transplantation. Methods: We assessed anti-PAR 1 and anti-ACE 2 antibody levels in patients with membranous nephropathy n= 18, focal and segmental glomerulosclerosis (FSGS) n = 25, lupus nephritis (LN) n = 17, IgA nephropathy n = 14, mesangial proliferative (non-IgA) glomerulonephritis n = 6, c-ANCA (cytoplasmic anti-neutrophil cytoplasmic antibodies) vasculitis n = 40, p (perinuclear)-ANCA vasculitis n = 16, and compared them with a healthy control group n = 22. Next, we observed the clinical course of the patients (creatinine, total protein, and albumin) up to 2 years and correlated the results with the level of antibodies. Results: The anti-PAR 1 antibody level was lower in membranous nephropathy and FSGS compared to the control group. Anti-PAR 1 antibody levels were higher in secondary compared to primary glomerulonephritis. Both anti-PAR 1 and anti-ACE 2 antibody levels correlated positively (in focal and segmental glomerulosclerosis) or negatively (in lupus nephritis) with total protein and albumin at different time points of observation. Anti-PAR 1 and anti-ACE 2 antibody levels correlated also with creatinine level at one time point of observation in IgA nephropathy. Anti-PAR 1 and anti-ACE 2 antibodies correlated with each other in membranous nephropathy, FSGS, and p- and c-ANCA vasculitis (p < 0.05). Conclusions: The anti-PAR 1 antibody level was lower in membranous nephropathy and focal and segmental glomerulosclerosis compared to the control group. Anti-PAR 1 antibody levels tend to be higher in secondary compared to primary glomerulonephritis. Full article

Background/Objectives: The human kallikrein-related peptidase 6 (KLK6), a serine protease with trypsin-like properties, belongs to the 15-member kallikrein (KLK) gene family and is predominantly recognized for its role in oncogenesis, neurodegenerative disorders, and skin conditions. Aquaporins (AQPs) are integral membrane proteins that facilitate water transport across cell membranes. AQP1 is constitutively active in the kidneys and plays a crucial role in reabsorbing filtered water, while AQP2 is regulated by vasopressin and is essential for maintaining body fluid homeostasis. The primary objective of the present study is to investigate the spatio-temporal expression patterns of KLK6, AQP1, and AQP2 throughout normal human nephrogenesis and congenital kidney and urinary tract (CAKUT) abnormalities: duplex kidneys, horseshoe kidneys, and dysplastic kidneys. Methods: An immunofluorescence analysis of KLK6, AQP1, and AQP2 was performed on 37 paraffin-embedded fetal kidney samples. The area percentage of KLK6 in the kidney cortex was calculated in normal developing samples during developmental phases 2, 3, and 4 and compared with CAKUT samples. Results: KLK6 exhibits distinct spatiotemporal expression patterns during human kidney development, with consistent localization in proximal tubules. Its subcellular positioning shifts from the basolateral cytoplasm in early phases to the apical cytoplasm in later stages, which may be strategically positioned to act on its substrate in either the peritubular space or the tubular fluid. KLK6 expression followed a quadratic trajectory, peaking at Ph4. This marked increase in the final developmental phase aligns with its strong expression in mature kidneys, suggesting a potential role in proximal tubule differentiation and functional maturation through facilitating extracellular matrix remodeling and activating proteinase-activated receptors, modulating the signaling pathways that are essential for tubular development. In duplex kidneys, structural abnormalities such as ureteral obstruction and hydronephrosis may upregulate KLK6 as part of a reparative response, while its downregulation could impair epithelial remodeling and cytoskeletal integrity, exacerbating dysplastic phenotypes. Conclusions: These findings highlight the potential of KLK6 involvement in normal kidney development and the pathology of CAKUT. Full article

The accumulation of cadmium (Cd) and microplastics (MPs) can have major deleterious effects on the health of marine ecosystems and organisms, including the pearl oyster Pinctada fucata martensii. Here, we characterized the effects of Cd and MPs on key biochemical parameters of P. f. martensii via an experiment with various treatments. Pearl oysters were exposed to either only Cd (5 or 50 μg/L), only MPs (5 mg/L), or both Cd and MPs for 2 d, and this was followed by a 5-day recovery period. Measurements of the activities of lipase, amylase, protease, T-ATPase, catalase, glutathione peroxidase, acid phosphatase, and alkaline phosphatase enzymes, as well as the malondialdehyde content in the hepatopancreas, were made at various time points during the experiment. Metabolomics analysis of the gills was also performed. Significant interactions between time and treatment on lipase, protease, and catalase activities were observed. However, no significant effect of time–treatment interactions on amylase and T-ATPase activities was observed. Enzyme activities varied among groups both during the exposure period (6 to 48 h) and the recovery period. The malondialdehyde content was also increased throughout the experiment. Pathway analysis indicated that the purine metabolism, glycerophospholipid metabolism, nucleotide metabolism, arachidonic acid metabolism, neuroactive ligand–receptor interaction, and linoleic acid metabolism pathways were the most commonly affected under different treatments. The findings of our study revealed the differential effects of exposure time and treatment on enzyme activities and metabolites and their respective pathways. Our findings enhance our understanding of the biochemical responses of the pearl oyster P. f. martensii to environmental stressors, particularly Cd and MPs. Full article

Patients infected with SARS-CoV-2 may develop mild respiratory symptoms but also Acute Respiratory Distress Syndrome (ARDS). Additionally, severe systemic inflammation contributes to morbidity and mortality. The SARS-CoV-2 virus enters the cell by binding to the angiotensin-converting enzyme 2 (ACE2) receptor, followed by cleavage by transmembrane serine protease 2 (TMPRSS2). Vasoactive intestinal peptide (VIP) is known for its immune-modulating effects by suppressing the release of pro-inflammatory cytokines and enhancing regulatory T-cells. Furthermore, it has been tested in SARS-CoV-2-related clinical trials. We set out to investigate its role in the setting of SARS-CoV-2 infection in vitro. Epithelial cells (CaCo-2) were stimulated with SARS-CoV-2 spike protein, treated with native VIP and analyzed to investigate the mRNA and surface expression of ACE2 and TMPRSS2, the enzyme activity of TMPRSS2 and the infection rate by a SARS-CoV-2 pseudovirus. VIP downregulated ACE2 and TMPRSS2 mRNA and surface expression. Beyond these direct effects, VIP mediates the shedding of surface-expressed ACE2 and TMPRSS2 via upregulation of a sheddase protease (ADAM10). Functionally, these dual mechanisms of VIP-mediated downregulation of proteins involved in SARS-CoV-2 cell entry resulted in a reduced infection rate by the SARS-CoV-2 pseudovirus. These data imply that VIP hampers viral entry mechanisms based on SARS-CoV-2 and the linkage to ADAM10 may stimulate research in other indications beyond SARS-CoV-2. Full article

The ongoing emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has led to resistance against multiple coronavirus disease 2019 (COVID-19) vaccines and therapeutic medications, making the development of effective therapeutics against SARS-CoV-2 a high priority. Studies have shown that bioactive polyphenols, particularly those with triphenol groups, can effectively inhibit the activity of SARS-CoV-2 3-chymotrypsin-like protease (3CL^pro). However, the structural instability of polyphenols necessitates further research. To address this, we conducted a literature review to identify triphenol compounds that are either approved or currently undergoing clinical trials, assessing their potential to inhibit SARS-CoV-2 3CL^pro. Exifone and benserazide hydrochloride were identified as the inhibitors of SARS-CoV-2 3CL^pro among these compounds, using a fluorescence resonance energy transfer (FRET)-based assay. Benserazide hydrochloride was confirmed as a covalent binder to SARS-CoV-2 3CL^pro through time-dependent inhibition and kinetic analysis, with its binding mode elucidated by molecular docking. Notably, exifone not only inhibited the protease activity but also blocked the interaction between the host cell receptor angiotensin-converting enzyme 2 (ACE2) and the SARS-CoV-2 spike protein receptor binding domain (S-RBD), as identified by surface plasmon resonance (SPR) and flow cytometry. Additionally, exifone demonstrated antiviral activity against various SARS-CoV-2-S pseudovirus variants. In conclusion, the discovery of exifone and benserazide hydrochloride underscores the potential of polyphenols in developing conserved 3CL^pro inhibitors for coronaviruses, offering new strategies for the rapid development of effective drugs against both current and future coronavirus pandemics. Full article