Effects of low-dose rapamycin on lymphoid organs of mice prone and resistant to accelerated senescence.

Aging is a complex, natural, and irreversible phenomenon that subjects the body to numerous changes in the physiological process, characterized by a gradual decline in the organism's homeostatic mechanisms, closely related to immunosenescence. Here, we evaluated the regulation of immunosenescence in lymphoid organs of senescence-accelerated prone 8 (SAM-P8) and senescence-accelerated resistant 1 (SAM-R1) mice treated with a low dose of rapamycin (RAPA). Mice were treated with a dose of 7.1 µg/kg RAPA for 2 months and had body mass and hematological parameters analyzed prior and during treatment. Cellular and humoral parameters of serum, bone marrow, thymus, and spleen samples were evaluated by ELISA, histology, and flow cytometry. Changes in body mass, hematological parameters, cell number, and in the secretion of IL-1ß, IL-6, TNF-α, IL-7, and IL-15 cytokines were different between the 2 models used. In histological analyses, we observed that SAM-P8 mice showed faster thymic involution than SAM-R1 mice. Regarding the T lymphocyte subpopulations in the spleen, CD4+ and CD8+ T cell numbers were higher and lower, respectively, in SAM-P8 mice treated with RAPA, with the opposite observed in SAM-R1. Additionally, we found that the low dose of RAPA used did not trigger changes that could compromise the immune response of these mice and the administered dose may have contributed to changes in important lymphocyte populations in the adaptive immune response and the secretion of cytokines that directly collaborate with the maturation and proliferation of these cells.

Effect of coronaviruses on blood vessel permeability: potential therapeutic targets.

Coronavirus-induced diseases have afflicted humanity for several decades. This scenario was aggravated by the emergence of the coronavirus disease 2019 (named COVID-19) in Wuhan, China, in December 2019. Since then, COVID-19 has killed millions of people worldwide, probably the most devastating pandemic since HIV/AIDS. This review aimed to bring together important updated aspects related to coronavirus-induced diseases and the enhanced vascular permeability observed mainly in the lungs of affected people. The dysregulated vascular permeability in the lungs is of fundamental importance for coronaviruses-caused morbidity and mortality. Thus, as described in this review, it is a target of new and old drugs.

Infectious complications and optimising infection prevention for children with cochlear implants.

AIM: To describe the clinical epidemiology of children receiving cochlear implants, as well as the management and outcomes of cochlear implant infections and adherence to infection prevention measures. METHODS: A retrospective observational study was conducted in children ≤18 years who received cochlear implants in Western Australia's tertiary paediatric hospital. Information was obtained from medical and laboratory records regarding demographics, indication for implant, implant infection and preoperative Staphylococcus aureus screening/decolonisation. Immunisation history was examined using the Australian Immunisation Register. RESULTS: Overall, 118 children received cochlear implants, with 158 devices inserted (599 cochlear implant insertion-years). An implant infection rate of 3.8% (6/158) was identified during the study period (four pneumococcal and two community-acquired methicillin resistant S. aureus infections). All required surgical management, with an overall median duration of antibiotic therapy of 37 days (interquartile range (IQR) 29-48) and median length of stay of 8 days (IQR 8-9.5). All devices were retained and there were no relapses or deaths. Half of the children who developed cochlear implant infections (50%, 3/6) were up-to-date with additional pneumococcal vaccinations and no children (0%, 0/118) received S. aureus screening/decolonisation before implant insertion. CONCLUSIONS: Favourable outcomes were achieved with cochlear implant retention; however, the treatment was burdensome for families. We demonstrate significant scope to improve adherence to existing infection prevention strategies and provide direction for optimising preventative measures in the future. These include ensuring parental education, additional pneumococcal vaccinations and S. aureus decolonisation which are delivered as an infection prevention bundle to the growing population of infants receiving cochlear implants.

Immune spleen cells attenuate the inflammatory profile of the mesenteric perivascular adipose tissue in obese mice.

The perivascular adipose tissue (PVAT) differs from other fat depots and exerts a paracrine action on the vasculature. The spleen has an important role in the immune response, and it was observed to have either a protective role or a contribution to obesity-related diseases. However, the relation between spleen and PVAT is elusive in obesity. We investigated the role of spleen in the inflammatory profile of the mesenteric PVAT (mPVAT) from mice fed a high-fat diet (HFD) for 16 weeks. Male C57Bl/6 mice were sham-operated or splenectomized (SPX) and fed a HFD for 16 weeks. mPVAT morphology was evaluated by hematoxylin and eosin staining, infiltrated immune cells were evaluated by flow cytometry, inflammatory cytokines were evaluated by ELISA and the splenic cell chemotaxis mediated by mPVAT was evaluated using a transwell assay. In SPX mice, HFD induced adipocyte hypertrophy and increased immune cell infiltration and proinflammatory cytokine levels in mPVAT. However, none of these effects were observed in mPVAT from sham-operated mice. Spleen from HFD fed mice presented reduced total leukocytes and increased inflammatory markers when compared to the spleen from control mice. Chemotaxis of spleen cells mediated by mPVAT of HFD fed mice was reduced in relation to standard diet fed mice. The spleen protects mPVAT against the effects of 16-week HFD. This information was missing, and it is important because PVAT is different from other fat depots and data cannot be extrapolated from any type of adipose tissue to PVAT.

Gold nanoparticles reduce inflammation in cerebral microvessels of mice with sepsis.

BACKGROUND: Sepsis is an emergency medical condition that can lead to death and it is defined as a life-threatening organ dysfunction caused by immune dysregulation in response to an infection. It is considered the main killer in intensive care units. Sepsis associated-encephalopathy (SAE) is mostly caused by a sepsis-induced systemic inflammatory response. Studies report SAE in 14-63% of septic patients. Main SAE symptoms are not specific and usually include acute impairment of consciousness, delirium and/or coma, along with electroencephalogram (EEG) changes. For those who recover from sepsis and SAE, impaired cognitive function, mobility and quality of life are often observed months to years after hospital discharge, and there is no treatment available today to prevent that. Inflammation and oxidative stress are key players for the SAE pathophysiology. Gold nanoparticles have been demonstrated to own important anti-inflammatory properties. It was also reported 20 nm citrate-covered gold nanoparticles (cit-AuNP) reduce oxidative stress. In this context, we tested whether 20 nm cit-AuNP could alleviate the acute changes caused by sepsis in brain of mice, with focus on inflammation. Sepsis was induced in female C57BL/6 mice by cecal ligation and puncture (CLP), 20 nm cit-AuNP or saline were intravenously (IV) injected 2 h after induction of sepsis and experiments performed 6 h after induction. Intravital microscopy was used for leukocyte and platelet adhesion study in brain, blood brain barrier (BBB) permeability carried out by Evans blue assay, cytokines measured by ELISA and real time PCR, cell adhesion molecules (CAMs) by flow cytometry and immunohistochemistry, and transcription factors, by western blotting. RESULTS: 20 nm cit-AuNP treatment reduced leukocyte and platelet adhesion to cerebral blood vessels, prevented BBB failure, reduced TNF- concentration in brain, and ICAM-1 expression both in circulating polymorphonuclear (PMN) leukocytes and cerebral blood vessels of mice with sepsis. Furthermore, 20 nm cit-AuNP did not interfere with the antibiotic effect on the survival rate of mice with sepsis. CONCLUSIONS: Cit-AuNP showed important anti-inflammatory properties in the brain of mice with sepsis, being a potential candidate to be used as adjuvant drug along with antibiotics in the treatment of sepsis to avoid SAE.

Gold nanoparticles carrying or not anti-VEGF antibody do not change glioblastoma multiforme tumor progression in mice.

AIMS: Glioblastoma multiforme (GBM) is the most devastating malignant primary brain tumor known. Life expectance is around 15 months after diagnosis. Several events contribute to the GBM progression such as uncontrolled genetic cancer cells proliferation, angiogenesis (mostly vascular endothelial growth factor (VEGF)-mediated), tissue invasion, glioma stem cell activity, immune system failure, and a hypoxic and inflammatory tumor microenvironment. Tumor cells antiproliferative effect of 20 nm citrate-covered gold nanoparticles (cit-AuNP) has been reported, along with anti-inflammatory and anti-oxidative effects. We aimed to test whether either chronic treatment with 20 nm cit-AuNP or anti-VEGF antibody (Ig)-covered AuNP could reduce GBM progression in mice. MAIN METHODS: Effect of the gold nanoparticles on the GL261 glioblastoma cells proliferation in vitro, and on the GL261-induced glioblastoma cell growth in C57BL/6 mice in vivo were tested. Besides, fluorophore-conjugated gold nanoparticles penetration through the GL261 plasma cell membrane, gold labelling in brain parenchyma of glioblastoma-carrying mice, and VEGF expression into the tumor were evaluated. KEY FINDINGS: We observed cit-AuNP did no change the GL261 cells proliferation. Similarly, we demonstrated chronic treatment with either cit-AuNP or anti-VEGF Ig-covered AuNP did not modify the GL261 cells-induced GBM progression in mice. By the end, we showed AuNPs did not trespass in appreciable amount both the GL261 plasma cell membrane and the tumoral blood brain barrier (BBB), and did not change the VEGF expression into the tumor. SIGNIFICANCE: 20 nm cit-AuNP or anti-VEGF Ig covered-AuNP are not good tools to reduce GBM in mice, probably because they do not penetrate both tumor cells and BBB in enough amount to reduce tumor growing.

Insulin Modulates Inflammatory Cytokine Release in Acute Stages and Augments Expression of Adhesion Molecules and Leukocytes in Lungs on Chronic Stages of Paracoccidioidomycosis.

Type 1 diabetesmellitus (T1D) is caused by partial destruction of the insulin-producing beta cells in the pancreas and is a major issue for public health care worldwide. Reduced or impaired immunological responses, which render patients more susceptible to infections, have been observed in T1D, and this dysfunction is often related to a lack of insulin in the blood. Paracoccidioidomycosis is an important systemic mycosis endemic in Latin America. To evaluate the effects of T1D on this fungal infection and the modulatory effects of insulin, we induced diabetes in C57Bl/6 male mice (alloxan, 60 mg/kg), infected the mice (Pb18, 1 x 106 cells), and treated the mice with neutral protamine Hagedorn (NPH) insulin (2 IU/600 mg/dL blood glucose). Twenty-four hours after infection, infected diabetic mice showed reduced secretion of interferon (IFN)-γ and interleukine (IL)-12 p70 compared to infected nondiabetic controls. On the 45th day of infection, infected diabetic mice presented higher IFN-γ levels, a higher tumor necrosis factor (TNF)-α:IL-10 ratio, and lower adhesion molecule expression levels than nondiabetic mice. In the in vitro experiments, alveolar macrophages from diabetic animals showed reduced phagocytic activity compared to those from control animals at 4, 12, and 24 h. In infected diabetic mice, treatment with insulin restored IL-12 p70 levels at 24 h of infection, reduced IFN-γ levels and the TNF-α:IL-10 ratio at 45 days, and restored vascular cell adhesion molecule (VCAM)-1 expression in pulmonary blood vessels, and this treatment reduced the diminished phosphorylation of extracellular signal-regulated kinases (ERK) and increased nuclear factor-kappa-B(iκb)-α and jun amino-terminal kinases (JNK) p46 levels in infected nondiabetic mice. In addition, insulin promoted increased phagocytic activity in the alveolar macrophages of diabetic mice. These data suggest that T1D mice are more susceptible to Pb18 infection and that insulin modulates this inflammation in diabetic mice by augmenting the expression of adhesion molecules and leukocytes in the lungs and by reducing chronic inflammation.

3 Tesla MRI brain scanning under general anaesthesia in a paediatric 3 Tesla-compatible cochlear implant recipient, first reported case: Clinical considerations and implications for future practice.

OBJECTIVES: To demonstrate the safety and feasibility of the first reported case of a 3 Tesla MRI scan in a paediatric 3 Tesla-compatible cochlear implant recipient under general anaesthesia. MATERIALS AND METHODS: A three-year-old child with bilateral optic pathway glioma treated with chemotherapy, who subsequently received a right sided 3 Tesla-compatible cochlear implant for sensorineural hearing loss was examined. The CI device chosen was implanted due to its purported MRI compatibility. Following informed consent and hospital executive approval, the child underwent a 3 Tesla MRI scan to assess for growth of the optic pathway glioma. RESULTS: A 3 Tesla MRI scan of the brain was performed under general anaesthesia. There was expected artefact due to the magnet of the receiver stimulator. There was no malfunction of the implant noted after the procedure, and no neurological or otological complications. The child had five more uneventful 3 Tesla MRI scans of the brain without complications. CONCLUSION: This is the first reported case of a child with a 3 Tesla-compatible cochlear implant undergoing a 3 Tesla MRI scan of the brain under general anaesthesia. Provided manufacturer guidelines are adhered to, 3 Tesla MRI scanning should not be contraindicated in paediatric cochlear implant recipients with a compatible device.

Systemic arterial hypertension leads to decreased semen quality and alterations in the testicular microcirculation in rats.

Arterial hypertension is a cardiovascular disease that leads to important systemic alterations and drastically impairs normal organ function over time. Hypertension affects around 700 million men of reproductive age and hypertensive men present increased risk for reproductive disorders, such as erectile dysfunction. However, the link between arterial hypertension and male reproductive disorders is associative at best. Moreover, many studies have reported associations between decreased male fertility and/or semen quality and alterations to general male health. In this study we aim to investigate the effect of systemic high blood pressure in sperm quality, sperm functional characteristics and testicular physiology in a rat model. Hypertensive rats presented altered testicular morphology - mainly vascular alterations and impaired testicular vasomotion. Hypertensive rats also presented decrease in sperm concentration, DNA integrity and increased percentages of sperm with dysfunctional mitochondria, intracellular superoxide anion activity and abnormal morphology. This study provides mechanistic insights by which arterial hypertension affects the testes, evidencing the testes as another target organ for hypertension as well as its impact on sperm quality.

Mitochondrial DNA: A new driver for sex differences in spontaneous hypertension.

The prevalence of arterial hypertension (AH) is higher in men than in premenopausal women of the same age. AH has been characterized as a chronic inflammatory disease and activation of Toll-like receptors (TLR) by damage-associated molecular patterns (DAMPs) is involved. Mitochondrial DNA (mtDNA) may be released by end-organ damage, which is recognized and activates TLR9. The serum level of mtDNA is increased in AH. The aim of this study was to compare the serum mtDNA levels between male and female spontaneously hypertensive rats (SHR) and to evaluate the sex differences in the effect of mtDNA on the function, inflammation and signaling pathway related to TLR9 in the vasculature. Male and female 15-week-old SHR and Wistar rats were used to evaluate the arterial blood pressure, serum mtDNA, contractile response, inflammatory markers and signaling pathway related to TLR9. Male SHR had higher arterial blood pressure values and serum mtDNA compared to female SHR and to male and female normotensive Wistar rats. In male SHR aorta, mtDNA incubation increased the contractile response to phenylephrine, which was blunted by inhibition of TLR9, and also increased pro-inflammatory molecules IL-6 and TNF-α. However, in female SHR aorta, mtDNA incubation did not change the contractile response, reduced pro-inflammatory molecules and prevented oxidative stress. mtDNA incubation did not change the expression of TLR9, MyD88 and eNOS neither in male nor in female SHR aorta, but it increased the phosphorylation of ERK1/2 in male and reduced in female SHR aorta. The mtDNA differential modulation of vascular response in male and female SHR might contribute to sex differences in AH. This study contributes to the understanding of a need for more personalized therapeutic strategies for men and women with hypertension. Keywords: Sex differences, Arterial hypertension, Mitochondrial DNA, Toll-Like receptor 9.

Mechanisms of the effectiveness of poly(ε-caprolactone) lipid-core nanocapsules loaded with methotrexate on glioblastoma multiforme treatment.

PURPOSE: The low penetration of drugs across the blood-brain barrier (BBB) compromises the delivery of chemotherapeutic agents to the brain parenchyma and contributes to the poor prognosis of glioblastoma multiforme (GBM). We investigated the efficacy of methotrexate-loaded lipid-core nanocapsules (MTX-LNC) administered by the oral route to treat murine GBM, its ability to cross the BBB, and the mechanisms of MTX-LNC uptake by cultured GL261 glioma and BV2 microglia cells. MATERIALS AND METHODS: Female C57B/6 mice were used in intravital microscopy assays to investigate the penetrance of rhodamine B-label MTX-LNC (RhoB/MTX-LNC) in the brain after oral or IV administration, and to evaluate the BBB integrity. Intracranial implantation of GL261 cells was undertaken to induce a murine GBM model, and the effectiveness of oral MTX or MTX-LNC treatments (started on Day 10 of GBM, every 2 days for 12 days) was quantified by tumor size, body weight, and leukogram. Pharmacological blockade of endocytic pathways was done to investigate the mechanisms of MTX-LNC uptake by cultured GL261 and microglia BV2 cells by using fluorescence microscopy. The effect of MTX-LNC or MTX on GL261 and BV2 proliferation was evaluated to compare the cytotoxicity of such compounds. RESULTS: RhoB/MTX-LNC was detected in brain parenchyma of mice after IV or oral administration, without any damage on BBB. Oral treatment with MTX-LNC reduced tumor volume and prevented weight loss and leukopenia in comparison to MTX-treated mice. MTX-LNC uptake by GL261 is caveolae-dependent, whereas endocytosis of MTX-LNC by BV2 occurs via phagocytosis and macropinocytosis. Both MTX-LNC and MTX reduced GL261 and BV2 proliferation; however, MTX-LNC showed higher efficacy in the inhibition of glioma proliferation. CONCLUSION: Together, we infer that the higher ability of MTX-LNC to cross the BBB and be captured by cancer and immune brain cells by different mechanisms is responsible for the higher efficacy of oral MTX-LNC treatment in GBM.

Lipid-Core Nanocapsules Act as a Drug Shuttle Through the Blood Brain Barrier and Reduce Glioblastoma After Intravenous or Oral Administration.

Lipid-core nanocapsules (LNC) are formed by an organogel surrounded by poly(epsilon-caprolactone) and stabilized by polysorbate 80. LNCs increase the concentration of drugs in the brain after oral or intravenous administration. We proposed to determine whether the drug is released from the LNC to cross the blood brain barrier (BBB) or the drug-loaded LNCs can cross the BBB to release the drug. We synthesized a Rhodamine B-polymer conjugate to prepare a fluorescent-labeled LNC formulation, and intravital microscopy was used to determine the ability of the LNCs to cross the brain barrier using different administration routes in C57BI/6 mice. A glioblastoma model was used to determine the impact of the LNC as a shuttle for treatment. After pial vessel exposure, intense fluorescence was detected inside the vessels 10 min after intravenous or 20 min after intraperitoneal injections of fluorescent-labeled LNC. The fluorescence was observed in the perivascular tissue after 30 and 60 min, respectively. Increased tissue fluorescence was detected 240 min after oral administration. The integrity of the barrier was determined during the experiments. Normal leukocyte and platelet adhesion to the vessel wall indicated that Rhodamine B-labeled LNC did not cause pial vessel alterations. After intravenous or oral administration, Rhodamine B-labeled LNC-containing co-encapsulated indomethacin and indomethacin ethyl ester exhibited similar behavior in pial vessels, being more efficient in the treatment of mice with glioblastoma than indomethacin in solution. Therefore, we demonstrated that LNCs act as drug shuttles through the BBB, delivering drugs in brain tissue with high efficiency and reducing glioblastoma after intravenous or oral administration.

Long-term in vivo polychlorinated biphenyl 126 exposure induces oxidative stress and alters proteomic profile on islets of Langerhans.

It has been recently proposed that exposure to polychlorinated biphenyls (PCBs) is a risk factor to type 2 diabetes mellitus (DM2). We investigated this hypothesis using long-term in vivo PCB126 exposure to rats addressing metabolic, cellular and proteomic parameters. Male Wistar rats were exposed to PCB126 (0.1, 1 or 10 µg/kg of body weight/day; for 15 days) or vehicle by intranasal instillation. Systemic alterations were quantified by body weight, insulin and glucose tolerance, and blood biochemical profile. Pancreatic toxicity was measured by inflammatory parameters, cell viability and cycle, free radical generation, and proteomic profile on islets of Langerhans. In vivo PCB126 exposure enhanced the body weight gain, impaired insulin sensitivity, reduced adipose tissue deposit, and elevated serum triglycerides, cholesterol, and insulin levels. Inflammatory parameters in the pancreas and cell morphology, viability and cycle were not altered in islets of Langerhans. Nevertheless, in vivo PCB126 exposure increased free radical generation and modified the expression of proteins related to oxidative stress on islets of Langerhans, which are indicative of early ß-cell failure. Data herein obtained show that long-term in vivo PCB126 exposure through intranasal route induced alterations on islets of Langerhans related to early end points of DM2.

Hyaluronidase decreases neutrophils infiltration to the inflammatory site.

OBJECTIVE: To evaluate the in vivo anti-inflammatory potential of bovine hyaluronidase (HYAL) using two different models of acute inflammation. METHODS: Air pouches were produced in the dorsal subcutaneous of mice and injected with phosphate saline solution or HYAL. The antiinflammatory action of HYAL was evaluated in carrageenan (Cg)-inflamed air pouches. After 4 and 24 h the cellular influx, protein exudation, cytokines and lipid mediators were evaluated. The action of HYAL on the rolling and adhesion of leukocytes was investigated in the LPS-stimulated mesenteric microcirculation by intravital microscopic. RESULTS: Treatment with HYAL reduced the cellular influx and protein exudation in non-inflamed and inflamed air pouches. HYAL treatment of Cg-inflamed air pouch reduced the production of tumor necrosis factor-alpha (TNF-α), interleukin-8 (IL-8), leukotriene B4 (LTB4) and LTC4, whereas prostaglandins E2 (PGE2) and D2 (PGD2) concentrations were unchanged. Histological analyses showed that HYAL administration diminished cell infiltration in the air-pouch lining. In LPS-stimulated mesenteric microcirculation, HYAL usage decreased rolling and adhesion of leukocytes, but did not affect the blood vessels diameters. CONCLUSION: The results demonstrate that HYAL inhibited cellular recruitment, edema formation and pro-inflammatory mediators production, resulting in decreased adherence of leukocytes to blood vessels and tissue infiltration. Our data suggest that HYAL may be considered an effective candidate to ameliorate acute inflammation.

Ultrasmall cationic superparamagnetic iron oxide nanoparticles as nontoxic and efficient MRI contrast agent and magnetic-targeting tool.

Fully dispersible, cationic ultrasmall (7 nm diameter) superparamagnetic iron oxide nanoparticles, exhibiting high relaxivity (178 mM(-1)s(-1) in 0.47 T) and no acute or subchronic toxicity in Wistar rats, were studied and their suitability as contrast agents for magnetic resonance imaging and material for development of new diagnostic and treatment tools demonstrated. After intravenous injection (10 mg/kg body weight), they circulated throughout the vascular system causing no microhemorrhage or thrombus, neither inflammatory processes at the mesentery vascular bed and hepatic sinusoids (leukocyte rolling, adhesion, or migration as evaluated by intravital microscopy), but having been spontaneously concentrated in the liver, spleen, and kidneys, they caused strong negative contrast. The nanoparticles are cleared from kidneys and bladder in few days, whereas the complete elimination from liver and spleen occurred only after 4 weeks. Ex vivo studies demonstrated that cationic ultrasmall superparamagnetic iron oxide nanoparticles caused no effects on hepatic and renal enzymes dosage as well as on leukocyte count. In addition, they were readily concentrated in rat thigh by a magnet showing its potential as magnetically targeted carriers of therapeutic and diagnostic agents. Summarizing, cationic ultrasmall superparamagnetic iron oxide nanoparticles are nontoxic and efficient magnetic resonance imaging contrast agents useful as platform for the development of new materials for application in theranostics.

Blood cells and endothelial barrier function.

The barrier properties of endothelial cells are critical for the maintenance of water and protein balance between the intravascular and extravascular compartments. An impairment of endothelial barrier function has been implicated in the genesis and/or progression of a variety of pathological conditions, including pulmonary edema, ischemic stroke, neurodegenerative disorders, angioedema, sepsis and cancer. The altered barrier function in these conditions is often linked to the release of soluble mediators from resident cells (e.g., mast cells, macrophages) and/or recruited blood cells. The interaction of the mediators with receptors expressed on the surface of endothelial cells diminishes barrier function either by altering the expression of adhesive proteins in the inter-endothelial junctions, by altering the organization of the cytoskeleton, or both. Reactive oxygen species (ROS), proteolytic enzymes (e.g., matrix metalloproteinase, elastase), oncostatin M, and VEGF are part of a long list of mediators that have been implicated in endothelial barrier failure. In this review, we address the role of blood borne cells, including, neutrophils, lymphocytes, monocytes, and platelets, in the regulation of endothelial barrier function in health and disease. Attention is also devoted to new targets for therapeutic intervention in disease states with morbidity and mortality related to endothelial barrier dysfunction.

In vivo and in vitro toxicity and anti-inflammatory properties of gold nanoparticle bioconjugates to the vascular system.

Gold nanoparticle (AuNP) bioconjugates have been used as therapeutic and diagnostic tools; however, in vivo biocompatibility and cytotoxicity continue to be two fundamental issues. The effect of AuNPs (20 nm) conjugated with antibody [immunoglobulin G (IgG)], albumin, protein A, PEG4000, and citrate (cit) were evaluated in vitro using primary human cells of the vascular system. AuNP bioconjugates did not cause lysis of human erythrocytes, apoptosis or necrosis of human leukocytes, and endothelial cells in vitro, although AuNPs had been internalized and detected in the cytoplasm. Moreover, the influence of AuNPs on rheological parameters, blood and vessel wall characteristics was investigated in vivo by intravital microscopy assay using male Wistar rats mesentery microcirculation as model. Intravenous injection of AuNP-IgG or cit-AuNP did not cause hemorrhage, hemolysis or thrombus formation, instead suppressed the leukocyte adhesion to postcapillary vessel walls, an early stage of an inflammatory process. Furthermore, AuNP-IgG abrogated the expression of platelet-endothelial cell adhesion molecule-1, chemotaxis, and oxidative burst activation on neutrophils after leukotriene B4 stimulation, a membrane receptor-dependent stimulus, thus confirming their anti-inflammatory effects in vitro. The expression of oxidative burst activation was also suppressed after stimulating AuNP-IgG-treated neutrophils with lipid-soluble phorbol myristate acetate (PMA), confirming the direct intracellular action of AuNP-IgG on the inflammatory process in vitro. Our in vitro and in vivo experimental approaches highlighted the great potentiality of AuNP bioconjugates for therapeutic and diagnostic applications by parenteral routes.

Synergistic effects of high blood cholesterol and hypertension on leukocyte and platelet recruitment in the cerebral microcirculation.

Hypertension or hypercholesterolemia can induce a proinflammatory and prothrombogenic phenotype in the microcirculation of the brain; however, less is known about how the combination of these risk factors affects the vasculature. We recently reported that a moderate (60%) increase in plasma cholesterol blunts the recruitment of leukocytes and platelets in the cerebral microvessels elicited by hypertension. In this study, we examined whether larger increments in blood cholesterol (4-fold) exerts a similar modulating influence on the vasculature in the presence of hypertension. Apolipoprotein E-knockout mice with deoxycorticosterone acetate salt-induced hypertension were placed on a high-cholesterol diet and exhibited exaggerated leukocyte and platelet adhesion responses in cerebral microvessels. Intermittent feeding (every fourth day) with high-cholesterol diet yielded similar phenotypic changes in the vasculature. Once the mice were placed on high-cholesterol diet, 4 days on normal diet (ND) were needed to revert to a normal vascular phenotype. Angiotensin II type 1 receptors and reactive oxygen species seem to contribute to the vascular responses induced by hypercholesterolemia and hypertension. Our findings indicate that the combination of hypertension and large increases in plasma cholesterol concentration results in a severe, but reversible, inflammatory and thrombogenic phenotype in the cerebral microvasculature.