Mitigation of SARS-CoV-2 by Using Transition Metal Nanozeolites and Quaternary Ammonium Compounds as Antiviral Agents in Suspensions and Soft Fabric Materials.

Introduction: The coronavirus disease 2019 (COVID-19) pandemic has demonstrated the need for novel, affordable, and efficient reagents to help reduce viral transmission, especially in high-risk environments including medical treatment facilities, close quarters, and austere settings. We examined transition-metal nanozeolite suspensions and quaternary ammonium compounds as an antiviral surface coating for various textile materials. Methods: Zeolites are crystalline porous aluminosilicate materials, with the ability of ion-exchanging different cations. Nanozeolites (30 nm) were synthesized and then ion-exchanged with silver, zinc and copper ions. Benzalkonium nitrate (BZN) was examined as the quaternary ammonium ion (quat). Suspensions of these materials were tested for antiviral activity towards SARS-CoV-2 using plaque assay and immunostaining. Suspensions of the nanozeolite and quat were deposited on polyester and cotton fabrics and the ability of these textiles towards neutralizing SARS-CoV-2 was examined. Results: We hypothesized that transition metal ion containing zeolites, particularly silver and zinc (AM30) and silver and copper (AV30), would be effective in reducing the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Additionally, AM30 and AV30 antiviral potency was tested when combined with a quaternary ammonium carrier, BZN. Our results indicate that exposure of SARS-CoV-2 to AM30 and/or AV30 suspensions reduced viral loads with time and exhibited dose-dependence. Antiviral activities of the combination of zeolite and BZN compositions were significantly enhanced. When used in textiles, AM30 and AV30-coated cotton and polyester fabrics alone or in combination with BZN exhibited significant antiviral properties, which were maintained even after various stress tests, including washes, SARS-CoV-2-repeated exposures, or treatments with soil-like materials. Conclusion: This study shows the efficacy of transition metal nanozeolite formulations as novel antiviral agents and establishes that nanozeolite with silver and zinc ions (AM30) and nanozeolite with silver and copper ions (AV30) when combined with benzalkonium nitrate (BZN) quickly and continuously inactivate SARS-CoV-2 in suspension and on fabric materials.

Oxidative stress-mediated inhibition of intestinal epithelial cell proliferation by silver nanoparticles.

Given the increasing use of silver nanoparticles (Ag NP) by the food and food packaging industries, this study investigated potential consequences of Ag NP ingestion in intestinal epithelial C2BBe1 cells. Treatment of proliferating cells (<10,000 cells/cm(2)) with 0.25 µg/cm(2) (1.25 µg/mL) of 23 nm Ag NP for 24 h induced 15% necrotic cell death and an 80% reduction in metabolic activity and decreased the GSH/GSSG ratio, indicating oxidative stress. G2/M phase cell cycle arrest and complete inhibition of cell proliferation was also induced by Ag NP treatment. Simulated in vitro digestion of Ag NP prior to cell exposure required the use of slightly higher doses to induce the same toxicity, likely due to slower Ag dissolution. Treatment of cells with silica, titania, and ZnO NP partially inhibited cell proliferation, but inhibition at low doses was unique to Ag NP. These data suggest that Ag NP induces oxidative stress, cell cycle arrest, and the inhibition of cell proliferation. However, toxicity and induction of oxidative stress were not observed in confluent cells (>100,000 cells/cm(2)) treated with 10 µg/cm(2) (40-50 µg/mL) Ag NP, indicating that these cells are less sensitive to Ag NP.

Uptake of bright fluorophore core-silica shell nanoparticles by biological systems.

Nanoparticles are used in a variety of consumer applications. Silica nanoparticles in particular are common, including as a component of foods. There are concerns that ingested nano-silica particles can cross the intestinal epithelium, enter the circulation, and accumulate in tissues and organs. Thus, tracking these particles is of interest, and fluorescence spectroscopic methods are well-suited for this purpose. However, nanosilica is not fluorescent. In this article, we focus on core-silica shell nanoparticles, using fluorescent Rhodamine 6G, Rhodamine 800, or CdSe/CdS/ZnS quantum dots as the core. These stable fluorophore/silica nanoparticles had surface characteristics similar to those of commercial silica particles. Thus, they were used as model particles to examine internalization by cultured cells, including an epithelial cell line relevant to the gastrointestinal tract. Finally, these particles were administered to mice by gavage, and their presence in various organs, including stomach, small intestine, cecum, colon, kidney, lung, brain, and spleen, was examined. By combining confocal fluorescence microscopy with inductively coupled plasma mass spectrometry, the presence of nanoparticles, rather than their dissolved form, was established in liver tissues.

Mammalian gastrointestinal tract parameters modulating the integrity, surface properties, and absorption of food-relevant nanomaterials.

Many natural chemicals in food are in the nanometer size range, and the selective uptake of nutrients with nanoscale dimensions by the gastrointestinal (GI) tract is a normal physiological process. Novel engineered nanomaterials (NMs) can bring various benefits to food, e.g., enhancing nutrition. Assessing potential risks requires an understanding of the stability of these entities in the GI lumen, and an understanding of whether or not they can be absorbed and thus become systemically available. Data are emerging on the mammalian in vivo absorption of engineered NMs composed of chemicals with a range of properties, including metal, mineral, biochemical macromolecules, and lipid-based entities. In vitro and in silico fluid incubation data has also provided some evidence of changes in particle stability, aggregation, and surface properties following interaction with luminal factors present in the GI tract. The variables include physical forces, osmotic concentration, pH, digestive enzymes, other food, and endogenous biochemicals, and commensal microbes. Further research is required to fill remaining data gaps on the effects of these parameters on NM integrity, physicochemical properties, and GI absorption. Knowledge of the most influential luminal parameters will be essential when developing models of the GI tract to quantify the percent absorption of food-relevant engineered NMs for risk assessment.

Minimal intestinal epithelial cell toxicity in response to short- and long-term food-relevant inorganic nanoparticle exposure.

Toxicity of commercial nanoparticles of titania, silica, and zinc oxides is being investigated in this in vitro study. Particles of these compositions are found in many food items, and thus this study is directed toward particle behavior in simulated digestion media and their interaction with intestinal epithelial cell line C2BBe1, a clone of Caco-2 cells, originally isolated from a human colon cancer. Even though the primary particle size of all three particles was below 50 nm, the particles appeared as aggregates in culture media with a negatively charged surface. In the presence of pepsin (pH 2), the charge on the titania became positive, and silica was almost neutral and aggregated extensively, whereas ZnO dissolved. For silica and titania, treatment with simulated intestinal digestive solution led to a strongly negatively charged surface and particle sizes approaching values similar to those in media. On the basis of infrared spectroscopy, we concluded that the surface of silica and titania was covered with bile salts/proteins after this treatment. Transmission electron microscopy indicated that the C2BBe1 cells internalized all three particles. Toxicity assays included investigation of necrosis, apoptosis, membrane damage, and mitochondrial activity. Titania and SiO2 particles suspended in media at loading levels of 10 µg/cm² exhibited no toxicity. With ZnO at the same loading level, mild toxicity was observed based only on the LDH assay and decrease of mitochondrial activity and not necrosis or apoptosis. Titania particles exposed to the simulated digestion media exhibited mild toxicity based on decrease of mitochondrial activity, likely due to transport of toxic bile salts via adsorption on the particle surface.

Evidence for the role of Epstein Barr Virus infections in the pathogenesis of acute coronary events.

BACKGROUND: The role of viral infections in the pathogenesis of atherosclerosis remains controversial largely due to inconsistent detection of the virus in atherosclerotic lesions. However, viral infections elicit a pro-inflammatory cascade known to be atherogenic and to precipitate acute ischemic events. We have published in vitro data that provide the foundation for a mechanism that reconciles these conflicting observations. To determine the relation between an early viral protein, deoxyuridine triphosphate nucleotidohydrolase (dUTPase), produced following reactivation of Epstein Barr Virus (EBV) to circulating pro-inflammatory cytokines, intercellular adhesion molecule-1 (ICAM-1) and acute coronary events. METHODOLOGY/PRINCIPAL FINDINGS: Blood samples were obtained from 299 patients undergoing percutaneous coronary intervention for stable angina (SA), unstable angina (UA), or acute myocardial infarction (AMI). Plasma concentrations of pro-inflammatory cytokines and neutralizing antibody against EBV-encoded dUTPase were compared in the three patient groups. AMI was associated with the highest measures of interleukin-6 (ANOVA p<0.05; 4.6 ± 2.6 pg/mL in patients with AMI vs. 3.2 ± 2.3 pg/mL in SA). ICAM-1 was significantly higher in patients with AMI (ANOVA p<0.05; 304 ± 116 pg/mL in AMI vs. 265 ± 86 pg/mL SA). The highest values of ICAM-1 were found in patients having an AMI and who were antibody positive for dUTPase (ANOVA p=0.008; 369 ± 183 pg/mL in AMI and positive for dUTPase vs. 249 ± 70 pg/mL in SA negative for dUTPase antibody). CONCLUSIONS/SIGNIFICANCE: These clinical data support a model, based on in vitro studies, by which EBV may precipitate AMI even under conditions of low viral load through the pro-inflammatory action of the early protein dUTPase that is produced even during incomplete viral replication. They further support the putative role of viral infections in the pathogenesis of atherosclerosis and coronary artery events.

Successful treatment of acyclovir-resistant herpes simplex virus type 2 proctitis with leflunomide in an HIV-infected man.

Human herpes simplex virus infections are very common and represent significant morbidity in the immunocompromised host. Patients with acyclovir resistant strains of HSV based on viral thymidine kinase gene mutations need alternative therapeutic approaches. Leflunomide has been shown to possess antiviral activity against several viruses. Herein we describe a case of acyclovir resistant HSV-2 proctitis in an HIV patient successfully treated with leflunomide without significant side effects.

Physicochemical and toxicological properties of commercial carbon blacks modified by reaction with ozone.

Ozonation of two commercial carbon blacks (CBs), Printex 90 (P90) and Flammruss 101 (F101), was carried out and changes in their morphology, physical properties, and cytotoxicity were examined. The hypothesis examined was that different methods of manufacture of CBs influence their chemical reactivity and toxicological properties. Structural changes were examined by X-ray photoelectron spectroscopy, infrared spectroscopy, Raman spectroscopy, and electron paramagnetic resonance spectroscopy (EPR). Introduction of surface oxygen functionality upon ozonation led to changes in surface charge, aggregation characteristics, and free radical content of the CBs. However, these changes in surface functionality did not alter the cytotoxicity and release of inflammation markers upon exposure of the CBs to murine macrophages. Interaction of macrophages with F101 resulted in higher levels of inflammatory markers than P90, and the only structural correlation was with the higher persistent radical concentration on the F101.

Contrast of the biological activity of negatively and positively charged microwave synthesized CdSe/ZnS quantum dots.

Quantum dots (QDs) are semiconductor nanocrystals that have found use in bioimaging, cell tracking, and drug delivery. This article compares the cytotoxicity and cellular interactions of positively and negatively charged CdSe/CdS/ZnS QDs prepared by a microwave method using a murine alveolar macrophage-like cell culture model. Keeping the core semiconductor the same, QD charge was varied by altering the surface capping molecule; negatively charged QDs were formed with mercaptopropionic acid (MPA-QDs) and positively charged QDs with thiocholine (THIO-QDs). The size and charge of these two QDs were investigated in three types of media (RPMI, RPMI + FBS, and X-VIVO serum-free media) relevant for the biological studies. MPA-QDs were found to have negative zeta potential in RPMI, RPMI + FBS, and serum-free media and had sizes ranging from 8 to 54 nm. THIO-QDs suspended in RPMI alone were <62 nm in size, while large aggregates (greater than 1000 nm) formed when these QDs were suspended in RPMI + FBS and serum-free media. THIO-QDs retained positive zeta potential in RPMI and were found to have a negative zeta potential in RPMI + FBS and nearly neutral zeta potential in serum-free media. In a cell culture model, both MPA-QDs and THIO-QDs caused comparable levels of apoptosis and necrosis. Both QDs induced significant tumor necrosis factor-alpha (TNF-α) secretion only at high concentrations (>250 nM). Both types of QDs were internalized via clathrin-dependent endocytosis. Using real-time, live cell imaging, we found that MPA-QDs interact with the cell surface within minutes and progress through the endocytic pathway to the lysosomes upon internalization. With the THIO-QDs, the internalization process was slower, but the pathways could not be mapped because of spectroscopic interference caused by QD aggregates. Finally, MPA-QDs were found to associate with cell surface scavenger receptors, while the THIO-QDs did not. This study indicates that the surface charge and aggregation characteristics of QDs change drastically in biological culture conditions and, in turn, influence nanoparticle and cellular interactions.

Silver nanoparticles embedded in zeolite membranes: release of silver ions and mechanism of antibacterial action.

BACKGROUND: The focus of this study is on the antibacterial properties of silver nanoparticles embedded within a zeolite membrane (AgNP-ZM). METHODS AND RESULTS: These membranes were effective in killing Escherichia coli and were bacteriostatic against methicillin-resistant Staphylococcus aureus. E. coli suspended in Luria Bertani (LB) broth and isolated from physical contact with the membrane were also killed. Elemental analysis indicated slow release of Ag(+) from the AgNP-ZM into the LB broth. The E. coli killing efficiency of AgNP-ZM was found to decrease with repeated use, and this was correlated with decreased release of silver ions with each use of the support. Gene expression microarrays revealed upregulation of several antioxidant genes as well as genes coding for metal transport, metal reduction, and ATPase pumps in response to silver ions released from AgNP-ZM. Gene expression of iron transporters was reduced, and increased expression of ferrochelatase was observed. In addition, upregulation of multiple antibiotic resistance genes was demonstrated. The expression levels of multicopper oxidase, glutaredoxin, and thioredoxin decreased with each support use, reflecting the lower amounts of Ag(+) released from the membrane. The antibacterial mechanism of AgNP-ZM is proposed to be related to the exhaustion of antioxidant capacity. CONCLUSION: These results indicate that AgNP-ZM provide a novel matrix for gradual release of Ag(+).

Inhibition of respiratory syncytial virus in vitro and in vivo by the immunosuppressive agent leflunomide.

BACKGROUND: Respiratory syncytial virus (RSV) is the primary cause of bronchiolitis and pneumonia in infants and young children worldwide and is often the cause of infections in bone marrow, solid organ transplant, cystic fibrosis and congenital heart disease patients, as well as respiratory tract disease in elderly adults. Treatment options are limited to ribavirin, which is only marginally effective, and passive immunoprophylaxis, which is very expensive. The immunosuppressive agent leflunomide has been shown to exert potent antiviral activity against several herpesviruses and polyomavirus BK. In the current study we have tested the hypothesis that leflunomide exerts antiviral activity against RSV. METHODS: Human Hep-2 or small airway epithelial cells were inoculated with RSV and treated with A77 1726, the active metabolite of leflunomide. Syncytia formation was assessed by immunohistochemical staining, and virus yield was measured by plaque assay. Cotton rats were intranasally inoculated with RSV, treated with leflunomide by gavage, and pulmonary viral loads were measured by plaque assay of lung homogenates. RESULTS: Phase contrast microscopy and immunohistochemical staining demonstrated profound attenuation of RSV-induced syncytia formation in infected cultures treated with A77 1726, the active metabolite of leflunomide. Plaque assays of virus yield in RSV-inoculated cell cultures demonstrated potent, dose-dependent A77-mediated antiviral activity. Likewise, pulmonary viral loads in RSV-inoculated cotton rats were reduced by >3 log by leflunomide compared with vehicle-treated controls, even when leflunomide treatment was delayed until day 3 post-inoculation. CONCLUSIONS: These findings suggest promise for leflunomide as a convenient, orally administered addition to the growing arsenal of antiviral therapeutics. While specific antiviral mechanisms remain to be elucidated, leflunomide shows unique bifunctional potential to both reduce viral load and, by virtue of its well-documented anti-inflammatory activity, attenuate the destructive inflammation associated with RSV disease.

Fenton activity and cytotoxicity studies of iron-loaded carbon particles.

The chemical and biological properties of iron-loaded manufactured carbon nanoparticles (Flammruss 101) were contrasted with those of an iron-loaded synthetic carbon particle. X-ray photoelectron spectroscopy was used to characterize the iron on the carbon particles. Production of hydroxyl free radicals via the Fenton reaction was monitored by electron paramagnetic resonance spectroscopy. The iron-loaded synthetic carbon particles produced a positive Fenton response, whereas the iron-loaded manufactured carbon particles did not. The source of the Fenton activity of the synthetic carbon particles is proposed to be a soluble iron compound that was formed during the synthesis of the particle. A likely candidate for the soluble iron species is Fe2F5, which was synthesized and its properties were examined. Higher toxicity of Fe2F5 toward murine macrophages compared with other simple iron salts was attributed to soluble iron that was stabilized by the fluoride ligand. The cytotoxicity of manufactured carbon particles toward murine macrophages decreased or remained unaltered upon impregnation with iron compounds.

Utility of leflunomide in the treatment of complex cytomegalovirus syndromes.

BACKGROUND: Cytomegalovirus (CMV) viremia that is resistant or refractory to the standard antiviral therapy still constitutes a major threat to high-risk transplant recipients. In addition, multiple CMV recurrences may lead to neutropenia because of repeated courses of therapy with ganciclovir derivatives. Leflunomide, a drug for rheumatoid arthritis, has been reported to have anti-CMV activity. This study reports on its use in 17 transplant recipients with complex CMV syndromes who had failed or were intolerant to other therapies. METHODS: Single-center, retrospective study. Clinical data were extracted from the electronic medical record. CMV DNA viral loads were performed by quantitative hybrid capture assay. RESULTS: Leflunomide was initiated after a median of three episodes of CMV viremia, with a mean peak viral load of 245,826 copies/mL. Initial clearance of CMV viremia was observed in 14 of 17 patients (82%), and 9 of 17 (53%) patients achieved a long-term suppression of CMV recurrences. Higher peak viral load and higher viral load at the start of leflunomide therapy were associated with failure to suppress viremia. The duration of leflunomide therapy ranged from 1 to 24 months (median 3.5 months, interquartile range 2.6-7 months), and the mean time to an undetectable CMV-DNA was 1.9 months. Adverse effects included diarrhea (35%), anemia (18%), and increased liver function tests (12%). CONCLUSIONS: Leflunomide, alone or in combination, has potential utility in treatment of complex CMV syndromes and in long-term suppression of viremia. The optimal duration of therapy and the balance of risks and benefits are not yet known.

Entrapment of ionic tris(2,2'-bipyridyl) ruthenium(II) in hydrophobic siliceous zeolite: O2 sensing in biological environments.

Synthesis of the ionic dye, tris(2,2'-bipyridyl) ruthenium(II) chloride (Ru(bpy) 3 2+.2Cl (-)) within the supercages of a highly hydrophobic zeolite Y is reported. Use of the neutral precursor Ru(bpy)Cl 2(CO) 2 allowed for high loading levels of Ru(bpy) 3 2+ (1 per 7 and 25 supercages). The emission quenching of the Ru(bpy) 3 2+-zeolite crystals dispersed in polydimethoxysiloxane (PDMS) films by dissolved oxygen in water was examined. The quenching data as a function of oxygen concentration was fit to a linear Stern-Volmer plot ( R2 = 0.98). Using the Stern-Volmer plot as calibration, changes in concentration of dissolved oxygen due to reaction with glucose in the presence of glucose oxidase was monitored. Human monocyte-derived macrophages internalized the submicron-sized Ru(bpy) 3 2+-zeolite crystals, and intracellular oxygen concentrations initiated by zymosan-mediated oxidative burst could be monitored by measuring the emission from Ru(bpy) 3 2+ by confocal fluorescence microscopy.

Human cytomegalovirus regulates bioactive sphingolipids.

Sphingolipids are present in membranes of all eukaryotic cells. Bioactive sphingolipids also function as signaling molecules that regulate cellular processes such as proliferation, migration, and apoptosis. Human cytomegalovirus (HCMV) exploits a variety of cellular signaling pathways to promote its own replication. However, whether HCMV modulates lipid signaling pathways is an essentially unexplored area of research in virus-host cell interactions. In this study, we examined the accumulation of the bioactive sphingolipids and the enzymes responsible for the biosynthesis and degradation of these lipids. HCMV infection results in increased accumulation and activity of sphingosine kinase (SphK), the enzyme that generates sphingosine 1-phosphate (S1P) and dihydrosphingosine 1-phosphate (dhS1P). We also utilized a mass spectrometry approach to generate a sphingolipidomic profile of HCMV-infected cells. We show that HCMV infection results in increased levels of dhS1P and ceramide at 24 h, suggesting an enhancement of de novo sphingolipid synthesis. Subsequently dihydrosphingosine and dhS1P decrease at 48 h consistent with attenuation of de novo sphingolipid synthesis. Finally, we present evidence that de novo sphingolipid synthesis and sphingosine kinase activity directly impact virus gene expression and virus growth. Together, these findings demonstrate that host cell sphingolipids are dynamically regulated upon infection with a herpes virus in a manner that impacts virus replication.

Epstein-Barr virus-encoded dUTPase enhances proinflammatory cytokine production by macrophages in contact with endothelial cells: evidence for depression-induced atherosclerotic risk.

Increased levels of proinflammatory cytokines, TNF-alpha and IL-6, predict mortality and morbidity. In cardiovascular disease patients, they are observed in atherosclerotic lesions and serum. Factors behind the increased levels of these cytokines are multifaceted and may include latent herpesviruses, such as Epstein-Barr virus (EBV) that can be reactivated by stress. Previously, we showed that the EBV-encoded deoxyuridine triphosphate nucleotidohydrolase (dUTPase), a protein synthesized in the early phase of virus replication, can induce human monocytes/macrophages to produce TNF-alpha and IL-6. In this study, we modeled the interactions that take place between macrophages and endothelial cells in vivo using human umbilical vein endothelial cells (HUVEC). HUVEC were stimulated by soluble factors induced by EBV dUTPase-treated monocyte-derived macrophages (MDM) that resulted in the upregulation of VCAM-1 and ICAM-1. These changes were related to MDM production of TNF-alpha following the activation of NF-kappaB. In a previous study, chronically stressed dementia caregivers had elevations in plasma IL-6 levels, a risk for cardiovascular disease. We found a relationship between plasma IL-6 levels and neutralizing antibody titers to EBV dUTPase suggesting that one source of the plasma IL-6 observed in our previous study could be related to the effect of EBV-encoded dUTPase on macrophages. The results suggest that EBV-encoded dUTPase can enhance production of proinflammatory cytokines by monocytes/macrophages in contact with endothelial cells of blood vessels, and may play a role in cardiovascular pathology and chronic inflammation.

In vitro effects of the active metabolite of leflunomide, A77 1726, on feline herpesvirus-1.

OBJECTIVE: To determine whether the active metabolite of leflunomide, A77 1726 (A77), inhibits replication of feline herpesvirus-1 (FHV-1) in cell culture. STUDY POPULATION: Crandell Rees feline kidney (CRFK) cell cultures. PROCEDURES: Cell cultures were inoculated with FHV-1 and treated simultaneously with concentrations of A77 ranging from 0 to 200microM. The antiviral effect of A77 was determined by use of conventional plaque reduction assays. The effect of A77 on viral load was determined via real-time PCR analysis, and transmission electron microscopy was used to evaluate the effect of A77 on viral morphology. To determine whether the antiviral effect was attributable to alterations in CRFK cell viability and number, CRFK cells were treated with various concentrations of A77 and stained with Annexin V and propidium iodide to assess apoptosis and a mitochondrial function assay was used to determine cell viability. RESULTS: Concentrations of A77 > or = 20microM were associated with substantial reduction in plaque number and viral load. Concentrations > or = 100microM were associated with complete suppression of plaque formation. At low concentrations of A77, clusters of intracytoplasmic virus particles that appeared to lack tegument and an external membrane were detected. Treatment of uninfected CRFK cell monolayers with A77 was associated with reduction in mitochondrial function with minimal evidence of apoptosis. CONCLUSIONS AND CLINICAL RELEVANCE: Leflunomide may be an alternative to current calcineurin-based immunosuppressive protocols used in feline organ transplantation because of its antiherpesviral activity.

Inflammatory properties of iron-containing carbon nanoparticles.

Inflammatory responses following exposure of carbon nanoparticles to human macrophage and endothelial cells were employed as indicators of particulate biological activity. Hundred nanometer carbon particles (nC) with and without nonextractable surface-bound iron were synthesized using a templating approach, and human monocyte-derived macrophages (MDM) were exposed to various concentrations of these particulates. Supernatants recovered from MDM 24 h postexposure were assayed for the inflammatory cytokine tumor necrosis factor-alpha (TNFalpha) by a quantitative ELISA and tested for their ability to induce expression of intercellular adhesion molecule-1 (ICAM-1) on human endothelial cells (EC) by immunofluorescence flow cytometry. Data generated by these experiments demonstrated that nC-Fe was far more biologically active than nC. In addition, the chemical reactivity of nC-Fe toward decomposition of hydrogen peroxide to form hydroxyl radicals was significantly higher than that of nC and correlated well with the increase in the strength of the inflammatory response, though a direct proof of creation of hydroxyl radicals in the biological system is not provided. Comparison with micrometer-sized carbon and carbon-iron particles suggests that the chemical and biological reactivity is correlated with surface area.

The role of anti-endothelial cell antibody-mediated microvascular injury in the evolution of pulmonary fibrosis in the setting of collagen vascular disease.

We encountered 16 patients with connective tissue disease in whom pulmonary fibrosis developed. Routine light microscopic, ultrastructural, and direct immunofluorescent analyses were conducted, and circulating antibodies, including those of endothelial cell derivation, were assessed using indirect immuno-fluorescence and Western blot assays. Underlying diseases were dermatomyositis, scleroderma, mixed connective tissue disease, sclerodermatomyositis, Sjögren syndrome, rheumatoid arthritis, and anti-Ro-associated systemic lupus erythematosus. Antibodies to one or more Ro, RNP, Jo 1, OJ, and/or nucleolar antigens were seen in all cases and antiphospholipid antibodies in half. All biopsies revealed microvascular injury in concert with intraparenchymal fibrosis; in some cases, there were corroborative ultrastructural findings of microvascular injury. Patterns of fibroplasia represented nonspecific interstitial pneumonitis and usual interstitial pneumonitis. We noted IgG, IgA, and/or complement in the septal microvasculature. In 6 cases with available serum samples, indirect immunofluorescent endothelial cell antibody studies were positive and Western Blot studies showed reactivity of serum samples to numerous endothelial cell lysate-derived proteins. Pulmonary fibrosis, a recognized complication of systemic connective tissue disease, develops in connective tissue disease syndromes with pathogenetically established immune-based microvascular injury at other sites. A similar mechanism of antibody-mediated endothelial cell injury may be the basis of the tissue injury and fibrosing reparative response.

Idiopathic pulmonary fibrosis related to endothelial injury and antiendothelial cell antibodies.

Mechanisms underlying idiopathic pulmonary fibrosis are not well understood. This paper presents data supporting the hypothesis that microvascular endothelial cell injury and antiendothelial cell antibodies play roles in human idiopathic pulmonary fibrosis. Serologic and pathologic features of 40 patients diagnosed with idiopathic pulmonary fibrosis were evaluated. All patients had open lung biopsies indicating either usual or nonspecific interstitial pneumonitis. All biopsies had morphologic evidence of microvascular injury to the endothelium, and direct immunofluorescence testing revealed variable deposition of IgG, IgM, or IgA within septal microvasculature suggestive of humorally mediated microvascular injury. Ultrastructural studies revealed changes of endothelial cell injury and necrosis and evidence of repetitive episodes of microvascular injury characterized by basement membrane zone collagen deposition and lamellation. Serum samples demonstrated reactivity to multiple endothelial cell antigenic epitopes, and indirect immunofluorescent testing demonstrated a prominent pattern of fluorescence in pulmonary endothelial cell preparations. Serum samples were positive in 37/40 patients for antiphospholipid antibodies with one fourth having positive lupus anticoagulant tests accompanied by thrombotic episodes. In patients with idiopathic pulmonary fibrosis, Factor VIII levels and C-reactive protein levels were also elevated, supporting the presence of endothelial cell injury and inflammation. These data underscore a potential role for immune-based microvascular injury in the evolution of usual or nonspecific interstitial pneumonitis and indicate that those patients have evidence of microvascular injury and endothelial cell necrosis. The high prevalence of antiphospholipid antibodies in these patients may lead to an inherent thrombophilic tendency.