ARGININE

Lysosomes are integral organelles that communicate cellular status to an entire tissue through mechanisms that are poorly defined. Here we developed an unbiased platform, integrating human plasma metabolomes and single-lysosome metabolomics, and show the byproducts of proteolysis are an unexpected class of signalling molecules. We show that dimethylarginine is a lysosomal-derived metabolite and a predictor of patient morbidity. Genetic depletion of a lysosomal exporter, cystinosin, accumulated dimethylarginine in lysosomes. Leveraging a lysosomal storage disease with cystinosin mutations, we show that the rapid plasticity of dimethylarginine compartmentalization ensures cell and tissue homeostasis. Strikingly, lysosomal entrapment of dimethylarginine in patients and disease models corresponds with lipid accumulation, lipid droplets and lipotoxicity. Exogenously restoring asymmetric dimethylarginine buffers oxidative stress, decreasing lipid peroxidation and cell death. These data show that dimethylarginine engages an interorganellar process-with peroxisomes, lysosomes and lipid droplets-that confers a crucial adaptive response mechanism.

The present study evaluates the effect of different novel tooth gel formulations combining L-arginine, ginger and eggshell on artificially demineralized enamel. This study used 50 bovine enamel specimens, divided into five groups according to the used toothpaste (n = 10): G1: Elmex Pro Argin (commercial positive control containing L-arginine), and four experimental groups; G2: ginger extract, G3: experimental eggshell + ginger, G4: experimental L-arginine + ginger, and G5: experimental L-arginine + eggshell + ginger. White-spot lesions were induced then the tested formulations were applied twice daily for one month. Evaluations at baseline, post-demineralization, and post-remineralization included Vickers microhardness (VMH), Scanning electron microscope (SEM), Energy Dispersive X-ray Analysis (EDX), elemental mapping and Confocal Laser Scanning Microscopy (CLSM). Also, antibacterial activity was assessed against commensal and cariogenic bacteria. After remineralization, all experimental groups showed a statistically significant increase in microhardness compared to their corresponding demineralized values (P < 0.001). Arginine-containing formulations (G4 and G5) showed statistically significant higher microhardness values and Calcium content following EDX analysis compared to the non-arginine formulations (G2 and G3) (P < 0.05). In agar well diffusion assay, the arginine-containing formulations (G1, G4, and G5) produced statistically significantly larger inhibition zones against both cariogenic and commensal bacterial species compared with the arginine free formulations (G2 and G3) at P < 0.05. The synergy of L-arginine with ginger and eggshell extract provides enhanced enamel remineralization, and antimicrobial efficacy, positioning these natural tooth gel formulations as promising alternatives or adjuncts to conventional fluoride-based products.

Diabetic infected wounds heal poorly due to the synergistic effects of hyperglycemia, persistent microbial colonization, and chronic inflammation. We developed a pH-switchable artificial skin dressing TPI-PADL, to address these challenges. This system adapts to changes in the wound microenvironment over time. The dressing incorporates polydopamine and L-arginine modified PtAu nanozymes into a conductive ionogel-fiber scaffold. In the acidic and hyperglycemic conditions of early infection, the nanozymes exhibit glucose oxidase-like and cascade catalytic activities, increasing reactive oxygen species (ROS) production. The elevated ROS levels effectively kill bacteria and disrupt biofilms. As the wound environment shifts toward neutral pH, the nanozyme activity changes. The system begins to scavenge excess ROS and generate oxygen. The released oxygen reduces oxidative stress and improves local oxygen supply. These changes promote angiogenesis and guide macrophages toward a pro-healing phenotype. In vitro and in vivo evaluations confirm that TPI-PADL coordinates antibacterial, anti-inflammatory, antioxidant, and pro-regenerative effects. The ionogel network provides strain-sensing capability. This feature enables real-time monitoring of mechanical changes during healing. This strategy integrates therapy and sensing in a single platform for diabetic wound management.

We investigated whether post-menopausal females receiving hormone replacement therapy (HRT) exhibit greater nitric oxide (NO)-dependent cutaneous microvascular responses than those not receiving HRT, assessed via pharmacological NO synthase (NOS) inhibition during local heating. We also examined regional differences in microvascular response between and within groups. Twenty-one post-menopausal females (10 receiving HRT, 11 not receiving HRT) underwent assessment of cutaneous vascular conductance (CVC), expressed as a percentage of maximum vasodilation (%CVC max ), at the chest, abdomen, forearm, and calf using laser-Doppler flowmetry. Local skin temperature was raised from 33°C to 42°C for ∼30 min, followed by ∼40 min perfusion with 20 m<sc>m</sc>NG-nitro-L-arginine methyl ester (L-NAME; NOS inhibitor) using intradermal microdialysis. The NO contribution to vasodilation was defined as the difference in %CVC max between the 42°C and L-NAME plateau. There were no significant differences in the NO contribution to vasodilation between groups or between sites within groups (all p > 0.107). During baseline, females not receiving HRT demonstrated 7.6 [0.8, 14.4]% higher %CVC max at the forearm compared with abdomen (p = 0.021). During the 42°C heating plateau, this group also showed abdominal %CVC max values that were 11.8 [0.04, 23.5]% lower than the calf (p = 0.041) and 12.7 [1.1, 24.4]% lower than the forearm (p = 0.025). Females receiving HRT demonstrated 12.0 [2.4, 21.5]% greater abdominal %CVC max than those not receiving HRT (p = 0.014). Altogether, our findings indicate that HRT is not associated with NO-dependent cutaneous vasodilation during local heating in post-menopausal females but is associated with regional heterogeneity in cutaneous vasodilatory responses.

The self-assembly in aqueous solutions, cytocompatibility, and collagen production of lipopeptide C 16 -KTTKS and a variant with arginine substitution for lysine, C 16 -RTTRS, are investigated. C 16 -KTTKS is known commercially as Matrixyl and is used in cosmetic formulations as it can stimulate collagen production. The self-assembly and conformations and collagen-stimulating effects of the two lipopeptides in two salt forms, trifluoroacetate (TFA) and acetate, are compared. Lipopeptide C 16 -KTTKS self-assembles into nanotapes based on a multi-bilayer stacking across a pH range pH 4-7 and micelles at pH 2, with little influence of the counterion. In contrast, C 16 -RTTRS forms a substantial population of spherical micelles for the acetate salt for pH 2-7, but mainly nanotapes for the TFA salt for pH 4-7. Conditions for hydrogel formation by C 16 -KTTKS were identified. Both lipopeptides show good cytocompatibility to fibroblasts at sufficiently low concentration. The two lipopeptides also stimulate collagen production in Human Dermal Fibroblasts (HDFa) at low concentration (0.0062 wt%). No significant effect of the counterion was noted on cell viability or collagen production. Our results suggest that the peptide sequence influences the pH-dependent self-assembly properties and that this can be modulated for certain lipopeptides by the nature of the counterions.

Corneal alkali burns (CAB) represent a devastating form of ocular trauma characterized by the rapid penetration of alkaline agents, triggering a destructive cascade of inflammatory infiltration, neovascularization, and fibrotic remodeling that compromises ocular transparency. Current pharmacological interventions are largely palliative and severely hampered by rapid precorneal clearance and poor epithelial penetrability. To overcome these formidable dynamic and static ocular barriers, we engineered a carrier-free, targeted nanoplatform via the spontaneous co-assembly of natural bioactives glycyrrhizin (GA) and puerarin (PUE), surface-functionalized with cyclic arginine-glycine-aspartic acid (GP@cRGD NPs). The GP@cRGD NPs exhibited robust physicochemical stability and rapid release kinetics precisely tailored for acute trauma intervention. Crucially, cRGD modification significantly enhanced precorneal retention and trans-epithelial penetration via integrin-targeted interactions. In vivo evaluations demonstrated that topical administration of GP@cRGD NPs markedly accelerated epithelial regeneration, suppressed pathological neovascularization, and successfully restored corneal optical clarity in a murine CAB model. Mechanistically, in vivo transcriptomic profiling and immunofluorescence corroborated that this nanomedicine synergistically reprogrammed the local immune microenvironment by directly inhibiting M1 macrophage polarization and extinguishing downstream pro-inflammatory and pro-fibrotic signaling cascades. Ultimately, this study demonstrates that our targeted, multi-mechanistic nano-formulation holds substantial promise for clinical translation, emerging as a powerful therapeutic intervention against severe chemical burns of the eye.

Transdermal drug delivery (TDD) is a non-invasive and painless drug delivery method, making it a compelling alternative to conventional methods, such as oral intake and intravenous injection. Although TDD holds promise, it faces challenges owing to the complex structure of the human skin. In particular, the stratum corneum (SC) serves as a significant barrier to drug absorption, hindering the passage of larger molecules. The TDD of vitagen, a stable L-ascorbic acid derivative with antioxidant properties, remains challenging because of its limited skin permeability. To address this issue, we prepared an ionic complex between vitagen and a synthesized guanidine-rich molecular transporter, scyllo-inositol-G6 (scyllo-G6), as a permeation enhancer (vitagen/scyllo-G6). This ionic complex showed improved skin permeability compared to vitagen alone with negligible cytotoxicity, indicating that the molecular transporter is biocompatible. Franz cell diffusion experiments demonstrated that scyllo-G6 exhibited a higher penetration coefficient with vitagen than other common penetration enhancers, such as oleic acid and menthol. Additionally, our findings revealed that the vitagen/scyllo-G6 complex had a notably greater inhibition effect on intracellular reactive oxygen species (ROS) than when vitagen was complexed to other permeation enhancers. Furthermore, FITC-labelled vitagen (FITC-vitagen) complexed with scyllo-G6 (FITC-vitagen/scyllo-G6) exhibited improved cellular uptake and penetrated deeper into tissue sections in a mouse model than FITC-vitagen conjugated to an arginine hexamer (Arg6), indicating that scyllo-G6 is a more effective skin penetration enhancer than Arg6. These findings suggest that utilizing scyllo-G6 as molecular transporter to enhance the skin permeability of vitagen is a promising strategy for TDD of vitagen.

Arginase is a therapeutic enzyme with promising anticancer applications, driving the search for novel microbial producers for this enzyme with superior properties. Here, we report a new fungal strain, identified morphologically and genetically as Aspergillus niger AUMC16187 (GenBank: OR447698), isolated from soil as a potent arginase producer. The enzyme was purified to homogeneity via Sephadex G-50 gel filtration and characterized as a dimeric, thermostable metalloenzyme, most active at 40 °C and stable over a broad temperature range. Crucially, the purified arginase exhibited significant and selective cytotoxicity against human epidermoid carcinoma (A431) cells, with lesser effects on normal human skin fibroblasts (HSF). Its therapeutic effect was confirmed by flow cytometry. The unique combination of biochemical robustness and selective anticancer activity in this novel A. niger arginase underscores its high potential as a promising biocatalyst for targeted cancer therapy and other biomedical applications.

Infection by SARS-CoV-2 is associated with an uncontrolled and damaging inflammatory response during severe COVID-19 disease, during which immune cells, such as neutrophils, monocytes, and macrophages, release pro-inflammatory mediators leading to the development of acute respiratory distress syndrome. Mast cells may also contribute to the pathogenesis of COVID-19, as increased serum levels of their proteases are associated with the severity of the disease. Mast cells are strategically located in tissues that interface with the external environment, such as the skin, respiratory tract, and gastrointestinal mucosa, exhibiting microbicidal activities, including phagocytosis and the release of DNA embedded with granular proteins, known as DNA extracellular traps (DETs). We show that the inactivated SARS-CoV-2 virions and the SARS-CoV-2 recombinant Spike protein induce DET formation in the human mast cell line HMC-1, with participation of TLR2 and TLR4 recognition. Using pharmacological inhibitors, we demonstrate the involvement of reactive oxygen species (ROS), NF-кB, peptidyl arginine deiminase (PAD), calcium, and serine proteases in the formation of DETs by either stimulus. DETs were toxic to pulmonary epithelial and endothelial cells, with tryptase, H3 citrullinated histone, and DNA scaffold contributing to cytotoxicity by apoptosis. Exposure of infectious virions to DETs reduced SARS-CoV-2 infection in Calu-3 cells, suggesting that the viral particles were trapped and killed by DETs. Furthermore, we also detected DET structures, characterized by colocalization of tryptase, citrullinated histone H3, and DNA, in the lung biopsies of COVID-19 patients. Taken together, our results suggest a dual role for mast cell DETs during SARS-CoV-2 infection, as they damage both pulmonary epithelial and endothelial cells while capturing SARS-CoV-2 virions and inhibiting viral infection. Our findings are consistent with the assumption that mast cell DETs control the viral load by reducing SARS-CoV-2 infectivity.

Pressure ulcers (PUs) are prevalent chronic wounds associated with pain, infection, and prolonged hospitalisation. Adequate nutrition is important in both preventing and healing PUs; however, malnutrition frequently co-occurs and nutritional care in clinical practice remains suboptimal. This study aimed to explore healthcare professionals' knowledge, attitudes, practices, and perceived barriers to nutritional care for PU patients in hospitals, nursing homes, and home care settings. A cross-sectional survey of 284 Flemish and Dutch healthcare professionals was conducted between April and June 2024. Knowledge, attitudes, practices, and barriers related to nutritional management of PUs were assessed. Descriptive statistics and ordinal logistic regression were used to analyse data and identify gaps in implementation of nutritional interventions. Most respondents (93.7%, n = 266) agreed or strongly agreed that inadequate nutritional guidance leads to more wound-healing complications, with dietitians reporting higher knowledge than nurses (p < 0.01), reflecting their specialised training amid limited dietitian availability in Flemish/Dutch settings, where nurses often take on primary responsibility for nutritional tasks (e.g., screening and adjustments). However, more than 60% of all respondents reported insufficient knowledge of glutamine/arginine supplementation. Reported barriers included unclear guidelines (63.3%, n = 180), insufficient knowledge of effective interventions (70.4%, n = 200), and high costs of supplementation (80.3%, n = 228), indicating a need for clearer guidelines and targeted education and policy support. Although healthcare professionals acknowledge the important role of nutrition in PU management, significant knowledge gaps, particularly between dietitians and nurses, and systemic barriers hinder effective care. Clearer guidelines, targeted education, and supportive policy measures (e.g., standardised nurse-led protocols) are needed to strengthen nutritional practices and improve patient outcomes.

Psoriasis is a common immune-mediated skin disease driven largely by interleukin-17A (IL-17A). Although IL-17A plays a key role in disease pathogenesis, the underlying mechanisms remain incompletely understood. Through bioinformatic analysis, we discovered that proline/arginine-rich end leucine-rich repeat protein (PRELP) expression is upregulated in skin lesions from psoriasis patients following treatment with IL-17A inhibitors (secukinumab, ixekizumab, and brodalumab), despite being significantly downregulated in lesional compared to nonlesional skin at baseline. Experimental assays confirmed that IL-17A suppressed PRELP expression in keratinocytes, consistent with its reduced expression in lesional tissues from both murine models and human patients. Functionally, PRELP suppressed keratinocyte proliferation, promoted apoptosis, and attenuated activation of the NF-κB and MAPK pathways, along with downstream proinflammatory cytokine and chemokine production. By downregulating IL6 in keratinocytes, PRELP further attenuated local IL-17A production via IL6 modulation, suggesting a break in the feed-forward loop of psoriatic inflammation. Intradermal administration of AAV-K14-PRELP ameliorated psoriasis-like findings in mice, including erythema, scaling, epidermal hyperplasia, and Th17 cell infiltration. Mechanistically, IL-17A suppressed PRELP transcription by activating STAT3, which directly binds to the PRELP promoter as a transcriptional repressor. Collectively, our findings identify PRELP as a negative regulator of IL-17A signaling in psoriasis, acting through keratinocyte dysregulation and modulation of Th17 cells. Therapeutic strategies aimed at enhancing PRELP expression may represent a novel approach for treating psoriasis and other Th17-driven inflammatory diseases.

Antimicrobial peptides (AMPs), which were conserved constituents of the innate immune system, exhibit antimicrobial properties similar to those of traditional antibiotics and have a low potential for the development of resistance. Thus, they were showing a great capacity for application. This study performed screening of twelve candidate antimicrobial peptides by means of pig skin enzymatic hydrolysis and activity prediction. The synthesis of these peptides was undertaken using Fmoc solid phase synthesis and purified via HPLC than 95%. The Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus (SA) and Escherichia coli (E. coli) were selected to evaluate antibacterial activity in vitro. The results indicated that peptide P5 exhibited the most significant inhibitory effect on MRSA and SA, with an inhibition rate of 91.83%. Furthermore, its antibacterial activity against MRSA and SA was found to be stronger than that against E. coli, demonstrating a dose-dependent relationship. Growth curve analysis revealed that P5 completely inhibited the growth of MRSA within 16 h at 3 mg/mL. Cytotoxicity was assessed using the CCK-8 assay and live/dead cell staining. The survival rates of both L929 and MDCK cells exceeded 87%, indicating good biocompatibility. Transcriptome sequencing (RNA-seq) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analyses demonstrated that treatment with the P5 was associated with significant transcriptional changes in MRSA. The differentially expressed genes were enriched in the ABC transporter pathway, as well as pathways related to arginine biosynthesis and metabolism, histidine metabolism, and quorum sensing. These findings suggest a potential link between P5 and these pathways, thereby providing a foundation for future mechanistic studies. In conclusion, the porcine skin-derived antimicrobial peptide P5 exhibited significant antimicrobial activity, low cytotoxicity, and a mechanism of action that was distinct from traditional antibiotics, thereby demonstrating promising potential for clinical translation in the fight against drug-resistant bacterial infections.