Cytotoxicity of IFN-gamma and TNF-alpha for vascular endothelial cell is mediated by nitric oxide

Protective effect of phosphorylated Athyrium multidentatum (Doll.) Ching polysaccharide on vascular endothelial cells in vitro and in vivo

The purpose of this study was to prepare phosphorylated Athyrium multidentatum (Doll.) Ching polysaccharide (PPS) and investigate its protective effect on vascular endothelial cells (VECs) in vitro and in vivo and the underlying mechanisms. Sodium tripolyphosphate (STPP) and sodium trimetaphosphate (STMP) were used as phosphorylation reagents and PPS was characterized by Fourier transform infrared (FT-IR), 13 C nuclear magnetic resonance (13 C NMR) and 31 P nuclear magnetic resonance (31 P NMR) spectra. Chemical analysis demonstrated that PPS was composed of mannose, glucosamine, rhamnose, glucuronic acid, galacturonic acid, galactosamine, glucose, galactose, xylose, arabinose, and fucose with a molar ratio of 11.36:0.42:4.03:1.12:1.81:0.26:33.25:24.12:6.85:14.46:2.32 and a molecular weight of 28,837 Da. Results from in vitro and in vivo assays revealed that PPS protected human umbilical vein endothelial cells (HUVECs) against H2 O2 -induced oxidative injury and attenuated D-galactose-induced VECs damage in mice. RNA sequencing (RNA-seq) analysis identified 18 differentially expressed genes (DEGs) between D-galactose-treated and PPS-pretreated mice abdominal aorta. A deep analysis of these DEGs disclosed that PPS regulated the expression of genes involved in the functions of vascular endothelium repairment, cell growth and proliferation, cell survival and apoptosis, inflammation, angiogenesis and antioxidant, indicating that these biological processes might play crucial roles in the protective actions of PPS on VECs.

Sexuality, Intimacy, and Reproductive Health after Spinal Cord Injury

Spinal cord injury (SCI) is a life-altering event often accompanied by a host of anxiety-provoking questions and concerns in the minds of affected individuals. Questions regarding the ability to resume sexual activity, partner's satisfaction as well as the ability to have biological children are just a few of the unknowns facing patients following the devastating reality that is SCI. As a result of advances in SCI research over the last few decades, providers now have the knowledge and tools to address many of these concerns in an evidence-based and patient-centered approach. SCI can impair multiple components involved in sexual function, including libido, achieving and maintaining an erection, ejaculation, and orgasm. Many safe and effective fertility treatments are available to couples affected by SCI. Finally, learning to redefine one's self-image, reinforce confidence and self-esteem, and feel comfortable communicating are equally as important as understanding functionality in regaining quality of life after SCI. Thus, this review aims to highlight the current state of SCI research relating to sexual function, reproductive health, and the search for meaning.

Single-cell profiling reveals distinct adaptive immune hallmarks in MDA5+ dermatomyositis with therapeutic implications

Anti-melanoma differentiation-associated gene 5-positive dermatomyositis (MDA5⁺ DM) is an autoimmune condition associated with rapidly progressive interstitial lung disease and high mortality. The aetiology and pathogenesis of MDA5⁺ DM are still largely unknown. Here we describe the immune signatures of MDA5⁺ DM via single-cell RNA sequencing, flow cytometry and multiplex immunohistochemistry in peripheral B and T cells and in affected lung tissue samples from one patient. We find strong peripheral antibody-secreting cell and CD8⁺ T cell responses as cellular immune hallmarks, and over-stimulated type I interferon signaling and associated metabolic reprogramming as molecular immune signature in MDA5⁺ DM. High frequency of circulating ISG15⁺ CD8⁺ T cells at baseline predicts poor one-year survival in MDA5⁺ DM patients. In affected lungs, we find profuse immune cells infiltration, which likely contributes to the pro-fibrotic response via type I interferon production. The importance of type I interferons in MDA5⁺ DM pathology is further emphasized by our observation in a retrospective cohort of MDA5⁺ DM patients that combined calcineurin and Janus kinase inhibitor therapy show superior efficacy to calcineurin inhibitor monotherapy. In summary, this study reveals key immune-pathogenic features of MDA5⁺ DM and provides a potential basis for future tailored therapies.

New Insights into the Mechanism of Immune-Mediated Tissue Injury in Yellow Fever: The Role of Immunopathological and Endothelial Alterations in the Human Lung Parenchyma

Yellow fever (YF) may cause lesions in different organs. There are no studies regarding the in situ immune response in the human lung and investigating immunopathological aspects in fatal cases can help to better understand the evolution of the infection. Lung tissue samples were collected from 10 fatal cases of human yellow fever and three flavivirus-negative controls who died of other causes and whose lung parenchymal architecture was preserved. In YFV-positive fatal cases, the main histopathological changes included the massive presence of diffuse alveolar inflammatory infiltrate, in addition to congestion and severe hemorrhage. The immunohistochemical analysis of tissues in the lung parenchyma showed significantly higher expression of E-selectin, P-selectin, ICAM-1, VCAM-1 in addition to cytokines such as IL-4, IL-10, IL-13, TNF- α, IFN-γ and TGF-β compared to the negative control. The increase in immunoglobulins ICAM-1 and VCAM-1 results in strengthening of tissue transmigration signaling. E-selectin and P-selectin actively participate in this process of cell migration and formation of the inflammatory infiltrate. IFN-γ and TNF-α participate in the process of cell injury and viral clearance. The cytokines IL-4 and TGF-β, acting in synergism, participate in the process of tissue regeneration and breakdown. The anti-inflammatory cytokines IL-4, IL-10 and IL-13 also act in the reduction of inflammation and tissue repair. Our study indicates that the activation of the endothelium aggravates the inflammatory response by inducing the expression of adhesion molecules and cytokines that contribute to the rolling, recruitment, migration and eliciting of the inflammatory process in the lung parenchyma, contributing to the fatal outcome of the disease.

The association between diabetes and obesity with Dengue infections

Dengue, an arboviral disease is a global threat to public health as the number of Dengue cases increases through the decades and this trend is predicted to continue. Non-communicable diseases such as diabetes and obesity are also on an upward trend. Moreover, past clinical studies have shown comorbidities worsen the clinical manifestation of especially Severe Dengue. However, discussion regarding the underlying mechanisms regarding the association between these comorbidities and dengue are lacking. The hallmark of Severe Dengue is plasma leakage which is due to several factors including presence of pro-inflammatory cytokines and dysregulation of endothelial barrier protein expression. The key factors of diabetes affecting endothelial functions are Th1 skewed responses and junctional-related proteins expression. Additionally, obesity alters the lipid metabolism and immune response causing increased viral replication and inflammation. The similarity between diabetes and obesity individuals is in having chronic inflammation resulting in endothelial dysfunction. This review outlines the roles of diabetes and obesity in severe dengue and gives some insights into the plausible mechanisms of comorbidities in Severe Dengue.

Updating concepts on atherosclerotic inflammation: From pathophysiology to treatment

BACKGROUND

Atherosclerosis is recognized as a systemic low-grade inflammatory disease. Furthermore, the dysregulation of the inflammatory response and its timely resolution is a pivotal process in determining the clinical manifestations of cardiac and cerebral acute ischaemia following atherothrombosis.

METHODS

This narrative review is based on the material searched on PubMed up to October 2020. The search terms we used were as follows: "atherosclerosis, inflammation, acute myocardial infarction and ischemic stroke" in combination with "biomarker, inflammatory cells and molecules, treatment."

RESULTS

The expected goal of addressing inflammation for the treatment of atherosclerosis and its acute ischaemic complications is reducing mortality and morbidity related to atherosclerotic cardiovascular disease, which are currently the first cause of death and disability worldwide. In this narrative review, we summarize the evidence about the main cellular and molecular mechanisms of inflammation in atherogenesis, atherothrombosis and acute ischaemic complications, with particular focus on the potential molecular targets for novel pharmacological treatments.

CONCLUSION

Although a large amount of evidence from animal models of atherothrombotic disease, and promising results of clinical trials, anti-inflammatory treatments against atherosclerosis are not yet recommended. A deepest understanding of pathophysiological mechanisms underlying the mechanisms driving resolution of the acute inflammation will probably allow to identify the optimal molecular target.

Lipopolysaccharide-Enhanced Responses against Aryl Hydrocarbon Receptor in FcgRIIb-Deficient Macrophages, a Profound Impact of an Environmental Toxin on a Lupus-Like Mouse Model

Fc gamma receptor IIb (FcgRIIb) is the only inhibitory-FcgR in the FcgR family, and FcgRIIb-deficient (FcgRIIb^−/−) mice develop a lupus-like condition with hyper-responsiveness against several stimulations. The activation of aryl hydrocarbon receptor (Ahr), a cellular environmental sensor, might aggravate activity of the lupus-like condition. As such, 1,4-chrysenequinone (1,4-CQ), an Ahr-activator, alone did not induce supernatant cytokines from macrophages, while the 24 h pre-treatment by lipopolysaccharide (LPS), a representative inflammatory activator, prior to 1,4-CQ activation (LPS/1,4-CQ) predominantly induced macrophage pro-inflammatory responses. Additionally, the responses from FcgRIIb^−/− macrophages were more prominent than wild-type (WT) cells as determined by (i) supernatant cytokines (TNF-α, IL-6, and IL-10), (ii) expression of the inflammation associated genes (NF-κB, aryl hydrocarbon receptor, iNOS, IL-1β and activating-FcgRIV) and cell-surface CD-86 (a biomarker of M1 macrophage polarization), and (iii) cell apoptosis (Annexin V), with the lower inhibitory-FcgRIIb expression. Moreover, 8-week-administration of 1,4-CQ in 8 week old FcgRIIb^−/− mice, a genetic-prone lupus-like model, enhanced lupus characteristics as indicated by anti-dsDNA, serum creatinine, proteinuria, endotoxemia, gut-leakage (FITC-dextran), and glomerular immunoglobulin deposition. In conclusion, an Ahr activation worsened the disease severity in FcgRIIb^−/− mice possibly through the enhanced inflammatory responses. The deficiency of inhibitory-FcgRIIb in these mice, at least in part, prominently enhanced the pro-inflammatory responses. Our data suggest that patients with lupus might be more vulnerable to environmental pollutants.

Tumor necrosis factor-alpha and interferon-gamma induce inflammasome-mediated corneal endothelial cell death

PURPOSE

Chronic corneal endothelial cell (CEC) loss results in corneal edema and vision loss in conditions such as pseudophakic bullous keratopathy (PBK), Fuchs' dystrophy, and corneal graft failure. Low CEC density has been associated with an elevation of intraocular pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α and interferon (INF)-γ. These cytokines are capable of triggering pyroptosis, a programmed cell death mechanism mediated by the inflammasome, prompting the activation of the pro-inflammatory cytokine interleukin (IL)-1β, the perpetuation of inflammation, and subsequent damage of corneal endothelial tissue. Therefore, the purpose of this study was to determine the deleterious contribution of the inflammasome and pyroptosis to CEC loss.

METHODS

CECs from human donor corneas were treated ex vivo with TNF-α and IFN-γ for 48 h. Levels of caspase-1 and IL-1β were then assayed by ELISA, and the expression of caspase-1 and gasdermin-D (GSDM-D) were confirmed by immunofluorescence. Endothelial cell damage was analyzed by a lactate dehydrogenase (LDH) release assay, and oxidative stress was determined by measuring the levels of reactive oxygen species (ROS) in the culture media.

RESULTS

Inflammasome activation and oxidative stress were elevated in CECs following exposure to TNF-α and IFN-γ, which resulted in cell death by pyroptosis as determined by LDH release which was inhibited by the caspase-1 inhibitor Ac-YVAD-cmk.

CONCLUSION

CEC death is induced by the pro-inflammatory cytokines TNF-α and IFN-γ, which contribute to inflammasome activation. Moreover, the inflammasome is a promising therapeutic target for the treatment of chronic CEC loss.

Biomarkers in individualized management of chimeric antigen receptor T cell therapy

The development of chimeric antigen receptor (CAR) T cell immunotherapy has achieved promising results, both in clinical studies and in commercial products for patients with hematologic malignancies. Despite high remission rates of CAR-T cell therapy in previously untreatable, refractory and/or relapsed patients, several challenges in CAR-T therapy remain to be overcome, especially in integrating such therapies into personalized disease management approaches. Given the unique characteristics of CAR-T therapy, it is particularly urgent to identify biomarkers to maximize their clinical benefits. This systematic review summarizes clinically relevant biomarkers that may help individualized disease management in patients receiving CAR-T cell therapy in terms of toxicity warning, efficacy prediction and relapse monitoring. We summarize data from 18 clinical trials, including traditional indicators like cytokines, biochemical proteins, tumor burden, as well as potential novel indicators such as CAR-T cell expansion and persistency. The establishment of a biomarker-based system aimed at individualized management is recommended to guide better clinical application of CAR-T products.

Shenlian Extract Against Myocardial Injury Induced by Ischemia Through the Regulation of NF-κB/IκB Signaling Axis

Ischemic heart disease (IHD), caused predominantly by atherosclerosis, is a leading cause of global mortality. Our previous studies showed that Shenlian extract (SL) could prevent the formation of atherosclerosis and enhance the stability of atherosclerotic plaques. To further investigate the protective effects of SL on myocardial ischemic injury and its possible mechanisms, anesthetized dogs, ex vivo rat hearts, and H9c2 cardiomyocytes were used as models. The results showed that SL had a significant protective effect on the anesthetized dog ligating coronary artery model, reduced the degree of myocardial ischemia (Σ-ST), and reduced the scope of myocardial ischemia (N-ST). Meanwhile, SL alleviated ischemic reperfusion damage in ex vivo rat hearts with improved LVEDP and ± dp/dt_max values of the left ventricle. SL reduced the pathological changes of LDH, IL-1β, MDA, and NO contents, all of which are related to the expression of NF-κB. Further analysis by Bio-Plex array and signal pathway blocker revealed that the phosphorylation of IκB was a key factor for SL to inhibit myocardial ischemic injury, and the regulation of SL on IκB was primarily related to degradation of the IκB protein. These results provided dependable evidence that SL could protect against myocardial ischemic injury through the NF-κB signaling pathway.

Vascular Alterations in a Murine Model of Acute Graft-Versus-Host Disease Are Associated with Decreased Serum Levels of Adiponectin and an Increased Activity and Vascular Expression of Indoleamine 2,3-Dioxygenase

Graft-versus-host disease (GVHD) is the limiting complication after bone marrow transplantation (BMT), and its pathophysiology seems to be highly influenced by vascular factors. Our study aimed at elucidating possible mechanisms involved in vascular GVHD. For this purpose, we used a fully MHC-mismatched model of BALB/c mice conditioned according to two different intensity protocols with total body irradiation and transplantation of allogeneic (C57BL/6) or syngeneic bone marrow cells and splenocytes. Mesenteric resistance arteries were studied in a pressurized myograph. We also quantified the expression of indoleamine 2,3-dioxygenase (IDO), endothelial (eNOS), and inducible NO synthase (iNOS), as well as several pro- and anti-inflammatory cytokines. We measured the serum levels of tryptophan (trp) and kynurenine (kyn), the kyn/trp ratio (KTR) as a marker of IDO activity, and adiponectin (APN). The myographic study showed a correlation of GVHD severity after allogeneic BMT with functional vessel alterations that started with increased vessel stress and ended in eccentric vessel remodeling, increased vessel strain, and endothelial dysfunction. These alterations were accompanied by increasing IDO activity and decreasing APN levels in the serum of allogeneic animals. The mRNA expression showed significantly elevated IDO, decreased eNOS, and elevation of most studied pro- and anti-inflammatory cytokines. Our study provides further data supporting the importance of vessel alterations in GVHD and is the first to show an association of vascular GVHD with hypoadiponectinemia and an increased activity and vascular expression of IDO. Whether there is also a causative involvement of these two factors in the development of GVHD needs to be further investigated.

Antihypertensive methyldopa, labetalol, hydralazine, and clonidine reversed tumour necrosis factor-α inhibited endothelial nitric oxide synthase expression in endothelial-trophoblast cellular networks

Medications used to control hypertension in pregnancy also improve trophoblast and endothelial cellular interaction in vitro. Tumour necrosis factor-α (TNF-α) inhibits trophoblast and endothelial cellular interactions and simultaneously decreases endothelial nitric oxide synthase (eNOS) expression. This study investigated whether antihypertensive medications improved these cellular interactions by modulating eNOS and inducible nitric oxide synthase (iNOS) expression. Human uterine myometrial microvascular endothelial cells (UtMVECs) were pre-incubated with (or without) low dose TNF-α (0.5 ng/mL) or TNF-α plus soluble fms-like tyrosine kinase-1 (sFlt-1) (100 ng/mL). The endothelial cells were cultured on Matrigel. After endothelial cellular networks appeared, trophoblast derived HTR-8/SVneo cells were co-cultured in the presence of clinically relevant doses of methyldopa, labetalol, hydralazine or clonidine for 24 hours. Cells were retrieved from the Matrigel to extract mRNA and eNOS and iNOS expression were examined by quantitative PCR. Methyldopa, labetalol, hydralazine and clonidine reversed the inhibitory effect of TNF-α on eNOS mRNA expression. After pre-incubating endothelial cells with TNF-α and sFlt-1, all the medications except methyldopa lost their effect on eNOS mRNA expression. In the absence of TNF-α, antihypertensive medications did not change eNOS expression. The mRNA expression of iNOS was not affected by TNF-α or any medications. This study shows that selected antihypertensive medications used in the treatment of hypertension in pregnancy increase eNOS expression in vitro when induced by the inflammatory TNF-α. The anti-angiogenic molecule sFlt-1 may antagonise the potential benefit of these medications by interfering with the NOS pathway.

The transporter and permeability interactions of asymmetric dimethylarginine (ADMA) and L-arginine with the human blood-brain barrier in vitro

The blood–brain barrier (BBB) is a biological firewall that carefully regulates the cerebral microenvironment by acting as a physical, metabolic and transport barrier. This selectively permeable interface was modelled using the immortalised human cerebral microvascular endothelial cell line (hCMEC/D3) to investigate interactions with the cationic amino acid (CAA) L-arginine, the precursor for nitric oxide (NO), and with asymmetric dimethylarginine (ADMA), an endogenously derived analogue of L-arginine that potently inhibits NO production. The transport mechanisms utilised by L-arginine are known but they are not fully understood for ADMA, particularly at the BBB. This is of clinical significance giving the emerging role of ADMA in many brain and cerebrovascular diseases and its potential as a therapeutic target. We discovered that high concentrations of ADMA could induce endothelial dysfunction in the hCMEC/D3s BBB permeability model, leading to an increase in paracellular permeability to the paracellular marker FITC-dextran (40 kDa). We also investigated interactions of ADMA with a variety of transport mechanisms, comparing the data with L-arginine interactions. Both molecules are able to utilise the CAA transport system y⁺. Furthermore, the expression of CAT-1, the best known protein from this group, was confirmed in the hCMEC/D3s. It is likely that influx systems, such as y⁺L and b^0,+, have an important physiological role in ADMA transport at the BBB. These data are not only important with regards to the brain, but apply to other microvascular endothelia where ADMA is a major area of investigation.

•

ADMA interacts with a variety of transporters at the blood-brain barrier.

•

These included cationic amino acid transporters, including CAT-1.

•

Human blood-brain barrier endothelial cells express CAT-1.

•

ADMA at high concentrations can disrupt the blood-brain barrier.

•

This disruption is not linked to increased ROS at the blood-brain barrier.

Hypoxia-induced soluble CD137 in malignant cells blocks CD137L-costimulation as an immune escape mechanism

Hypoxia is a common feature in solid tumors that has been implicated in immune evasion. Previous studies from our group have shown that hypoxia upregulates the co-stimulatory receptor CD137 on activated T lymphocytes and on vascular endothelial cells. In this study, we show that exposure of mouse and human tumor cell lines to hypoxic conditions (1% O₂) promotes CD137 transcription. However, the resulting mRNA is predominantly an alternatively spliced form that encodes for a soluble variant, lacking the transmembrane domain. Accordingly, soluble CD137 (sCD137) is detectable by ELISA in the supernatant of hypoxia-exposed cell lines and in the serum of tumor-bearing mice. sCD137, as secreted by tumor cells, is able to bind to CD137-Ligand (CD137L). Our studies on primed T lymphocytes in co-culture with stable transfectants for CD137L demonstrate that tumor-secreted sCD137 prevents co-stimulation of T lymphocytes. Such an effect results from preventing the interaction of CD137L with the transmembrane forms of CD137 expressed on T lymphocytes undergoing activation. Indeed, silencing CD137 with shRNA renders more immunogenic tumor-cell variants upon inoculation to immunocompetent mice but which readily grafted on immunodeficient or CD8⁺ T-cell-depleted mice. These mechanisms are interpreted as a molecular strategy deployed by tumors to repress lymphocyte co-stimulation via CD137/CD137L.

Immunopathogenesis of ocular Behçet's disease

Behçet's disease (BD) is a chronic recurrent systemic inflammatory disorder of unknown etiology characterized by oral and genital ulcerations, skin lesions, and uveitis. The ocular involvement of BD, or Behçet's uveitis (BU), is characterized by panuveitis or posterior uveitis with occlusive retinal vasculitis and tends to be more recurrent and sight threatening than other endogenous autoimmune uveitides, despite aggressive immunosuppression. Although pathogenesis of BD is unclear, researches have revealed that immunological aberrations may be the cornerstone of BD development. General hypothesis of BD pathogenesis is that inflammatory response is initiated by infectious agents or autoantigens in patients with predisposing genetic factors and perpetuated by both innate and acquired immunity. In addition, a network of immune mediators plays a substantial role in the inflammatory cascade. Recently, we found that the immunopathogenesis of BU is distinct from other autoimmune uveitides regarding intraocular effector cell profiles, maturation markers of dendritic cells, and the cytokine/chemokine environment. In addition, accumulating evidence indicates the involvement of Th17 cells in BD and BU. Recent studies on genetics and biologics therapies in refractory BU also support the immunological association with the pathogenesis of BU. In this review, we provide an overview of novel findings regarding the immunopathogenesis of BU.

Endothelial dysfunction and altered mechanical and structural properties of resistance arteries in a murine model of graft-versus-host disease

A putative involvement of the vasculature seems to play a critical role in the pathophysiology of graft-versus-host disease (GVHD). We aimed to characterize alterations of mesenteric resistance arteries in GVHD in a fully MHC-mismatched model of BALB/c mice conditioned with total body irradiation that underwent transplantation with bone marrow cells and splenocytes from syngeneic (BALB/c) or allogeneic (C57BL/6) donors. After 4 weeks, animals were sacrificed and mesenteric resistance arteries were studied in a pressurized myograph. The expression of endothelial (eNOS) and inducible nitric oxide (NO)-synthase (iNOS) was quantified and vessel wall ultrastructure was investigated with electron microscopy. The myograph study revealed an endothelial dysfunction in allogeneic-transplant recipients, whereas endothelium-independent vasodilation was similar to syngeneic-transplant recipients or untreated controls. The expression of eNOS was decreased and iNOS increased, possibly contributing to endothelial dysfunction. Additionally, arteries of allogeneic transplant recipients exhibited a geometry-independent increase in vessels strain. For both findings, electron microscopy provided a structural correlate by showing severe damage of the whole vessel wall in allogeneic-transplant recipient animals. Our study provides further data to prove, and is the first to characterize, functional and structural vascular alterations in the early course after allogeneic transplantation directly in an ex vivo setting and, therefore, strongly supports the hypothesis of a vascular form of GVHD.

Imbalance between endothelial damage and repair: a gateway to cardiovascular disease in systemic lupus erythematosus

Atherosclerosis is accelerated in patients with systemic lupus erythematosus (SLE) and it leads to excessive cardiovascular complications in these patients. Despite the improved awareness of cardiovascular disease and advent of clinical diagnostics, the process of atherogenesis in most patients remains clinically silent until symptoms and signs of cardiovascular complications develop. As evidence has demonstrated that vascular damage is already occurring before clinically overt cardiovascular disease develops in lupus patients, intervention at the preclinical stage of atherogenesis would be plausible. Indeed, endothelial dysfunction, one of the earliest steps of atherogenesis, has been demonstrated to occur in lupus patients even when they are naïve for cardiovascular disease. Currently known “endothelium-toxic” factors including type 1 interferon, proinflammatory cytokines, inflammatory cells, immune complexes, costimulatory molecules, neutrophils extracellular traps, lupus-related autoantibodies, oxidative stress, and dyslipidemia, coupled with the aberrant functions of the endothelial progenitor cells (EPC) which are crucial to vascular repair, likely tip the balance towards endothelial dysfunction and propensity to develop cardiovascular disease in lupus patients. In this review, altered physiology of the endothelium, factors leading to perturbed vascular repair contributed by lupus EPC and the impact of proatherogenic factors on the endothelium which potentially lead to atherosclerosis in lupus patients will be discussed.

Pulmonary microvascular albumin leak is associated with endothelial cell death in murine sepsis-induced lung injury in vivo

Sepsis is a systemic inflammatory response that targets multiple components of the cardiovascular system including the microvasculature. Microvascular endothelial cells (MVEC) are central to normal microvascular function, including maintenance of the microvascular permeability barrier. Microvascular/MVEC dysfunction during sepsis is associated with barrier dysfunction, resulting in the leak of protein-rich edema fluid into organs, especially the lung. The specific role of MVEC apoptosis in septic microvascular/MVEC dysfunction in vivo remains to be determined. To examine pulmonary MVEC death in vivo under septic conditions, we used a murine cecal ligation/perforation (CLP) model of sepsis and identified non-viable pulmonary cells with propidium iodide (PI) by intravital videomicroscopy (IVVM), and confirmed this by histology. Septic pulmonary microvascular Evans blue (EB)-labeled albumin leak was associated with an increased number of PI-positive cells, which were confirmed to be predominantly MVEC based on specific labeling with three markers, anti-CD31 (PECAM), anti-CD34, and lectin binding. Furthermore, this septic death of pulmonary MVEC was markedly attenuated by cyclophosphamide-mediated depletion of neutrophils (PMN) or use of an anti-CD18 antibody developed for immunohistochemistry but shown to block CD18-dependent signaling. Additionally, septic pulmonary MVEC death was iNOS-dependent as mice lacking iNOS had markedly fewer PI-positive MVEC. Septic PI-positive pulmonary cell death was confirmed to be due to apoptosis by three independent markers: caspase activation by FLIVO, translocation of phosphatidylserine to the cell surface by Annexin V binding, and DNA fragmentation by TUNEL. Collectively, these findings indicate that septic pulmonary MVEC death, putatively apoptosis, is a result of leukocyte activation and iNOS-dependent signaling, and in turn, may contribute to pulmonary microvascular barrier dysfunction and albumin hyper-permeability during sepsis.

Infertility in men with spinal cord injury: research and treatment

Spinal cord injury (SCI) occurs most often to young men. Following SCI, most men are infertile due to a combination of erectile dysfunction, ejaculatory dysfunction and semen abnormalities. Erectile dysfunction may be treated by the same therapies that are used in the general population. Similarly, the same treatments that are effective to assist conception in couples with non-SCI male factor patients are effective in assisting conception in SCI male-factor patients. The most apparent differences in male-factor symptoms between SCI and non-SCI patients are the high occurrences of anejaculation and atypical semen profiles in men with SCI. Methods available to assist ejaculation in men with SCI include penile vibratory stimulation and EEJ. Use of surgical sperm retrieval as the first line of treatment for anejaculation in men with SCI is controversial. Most men with SCI have a unique semen profile characterized by normal sperm concentration, but abnormally low sperm motility. Toxic substances in the semen contribute to this problem. Despite impaired sperm parameters, pregnancy outcomes using sperm from men with SCI are similar to pregnancy outcomes using sperm from non-SCI men. Future studies should focus on improving natural ejaculation and improving semen quality in these men.

The effect of interferon γ on endothelial cell nitric oxide production and apoptosis

Background:

Nitric oxide (NO) is an important molecule in maintaining endothelial survival and normal function. It is a unique mediator, which may promote or suppress both inflammation and apoptosis. Endothelial cell (EC) injury, dysfunction, and death in response to cytokines, especially interferon gamma (IFN-γ), represent the critical event for the initiation of several inflammatory diseases.

Objective(s):

EC injury or death result in endothelial dysfunction that precedes the development of atherosclerosis and its subsequent vascular events. We examine the effect of different concentrations of IFN-γ on human umbilical vein ECs (HUVECs) NO production and apoptosis.

Materials and Methods:

HUVECs were cultured at 37°C for 24 h in the absence (control) or presence of 10, 100, and 1000 μg IFN-γ, respectively. The apoptotic cells were determined as annexin V-positive propidium iodide (PI)-negative cells by flow cytometry. Total nitrite concentration was measured in cell cultures supernatant by Griess method.

Results:

A comparison of the effect of IFN-γ on EC NO production with untreated cells showed that pretreatment of HUVEC with IFN-γ failed to have a significant effect on NO production by these cells at 10 and 100 U/mL, whereas it led to a significant decreased NO production at 1000 U/mL (P < 0.05). The cells stimulated with IFN-γ showed significantly higher apoptotic cells (PI negative and annexin V-positive cells) after 24 h, compared with cells with no stimulations (P < 0.05).

Conclusion:

IFN-γ has detrimental effects on ECs in high doses. This might be due to inducible NO synthase activation.

[Effects of peroxynitrite derived from nitric oxide on cultured bovine ocular explants]

INTRODUCTION

Several studies have reported a significant production of nitric oxide (NO) with peroxynitrite formation in the setting of intraocular inflammation. In a previous study, we showed the cytotoxic effect of nitrites and nitrates, stable metabolites of NO, on the various tissues forming the layers of the eye, with variable degrees of tissue sensitivity. This study aims to investigate the effect of peroxynitrite on whole ocular bovine explants in culture.

METHODS

Healthy ocular bovine eyes, obtained immediately upon enucleation, were dissected and samples were taken from the anterior and posterior segments, and then cultured in DMEM supplemented with 10% fetal bovine serum, 2mM L-glutamine and antibiotics. Cultures were treated with 3-morpholino-sydonimin N-ethyl-carbamide (SIN-1) (molecule which produces NO and superoxide anion O(2)(.-)) at varying concentrations (100 to 500 μM) over 24 hours. After incubation, the explants were fixed in 10% buffered formalin, and histological study was performed.

RESULTS

Most of the structures showed changes on tissue and cellular levels after incubation with the peroxynitrite donor and various responses depending on the concentration used. These observations reflect variable concentration-dependent tissue sensitivity. The epithelia (cornea, iris and ciliary process) showed high sensitivity in comparison with sclera, which developed greater resistance.

CONCLUSION

In all, our results indicate a deleterious effect of peroxynitrite on bovine ocular structures in vitro. This effect is proportional to the concentration used. These results corroborate those reported by other teams and suggest the role of peroxynitrite derived from NO in the ocular lesions observed in the setting of uveitis.

L-arginine enhances nitrative stress and exacerbates tumor necrosis factor-alpha toxicity to human endothelial cells in culture: prevention by propofol

Supplementation of L-arginine, a nitric oxide precursor, during the late phase of myocardial ischemia/reperfusion increases myocyte apoptosis and exacerbates myocardial injury, but the underlying mechanism is unclear. During myocardial ischemia/reperfusion, apoptosis of endothelial cells precedes that of cardiomyocyte. Tumor necrosis factor-alpha (TNF) production is increased during myocardial ischemia/reperfusion, which may exacerbate myocardial injury by inducing endothelial cell apoptosis. We postulated that L-arginine may exacerbate TNF-induced endothelial cell apoptosis by enhancing peroxynitrite-mediated nitrative stress. Cultured human umbilical vein endothelial cells were either not treated (control) or treated with TNF alone or with TNF in the presence of L-arginine, the nonselective nitric oxide synthase inhibitor N (omega)-nitro-L-arginine (L-NNA), propofol (an anesthetic that scavenges peroxynitrite), or L-arginine plus propofol, respectively, for 24 hours. TNF increased intracellular superoxide and hydrogen peroxide production accompanied by increases of inducible nitric oxide synthase (iNOS) protein expression and nitric oxide production. This was accompanied by increased protein expression of nitrotyrosine, a fingerprint of peroxynitrite and an index of nitrative stress, and increased endothelial cell apoptosis. L-arginine did not enhance TNF-induced increases of superoxide and peroxynitrite production but further increased TNF-induced increase of nitrotyrosine production and exacerbated TNF-mediated cell apoptosis. L-NNA and propofol, respectively, reduced TNF-induced nitrative stress and attenuated TNF cellular toxicity. The L-arginine-mediated enhancement of nitrative stress and TNF toxicity was attenuated by propofol. Thus, under pathological conditions associated with increased TNF production, L-arginine supplementation may further exacerbate TNF cellular toxicity by enhancing nitrative stress.

Interleukin-10 inhibits the in vivo and in vitro adverse effects of TNF-alpha on the endothelium of murine aorta

TNF-α is a proinflammatory cytokine and is an important mediator of maternal endothelial dysfunction leading to preeclampsia. In this study, we tested whether IL-10 protects against TNF-α-induced endothelial dysfunction in murine aorta. In in vitro experiments, aortic rings of C57BL/6 female mice were incubated in Dulbecco's modified Eagle's medium in the presence of either vehicle (distilled H(2)O), TNF-α (4 nmol/l), or recombinant mouse IL-10 (300 ng/ml) or in the presence of both TNF-α and IL-10 for 22 h at 37°C. In in vivo experiments C57BL6/IL-10 knockout female mice were treated with saline or TNF-α (220 ng·kg(-1)·day(-1)) for 14 days. Aortic rings were isolated from in vitro and in vivo experiments and mounted in a wire myograph (Danish Myotech) and stretched to a tension of 5 mN. Endothelium-dependent relaxation was assessed by constructing cumulative concentration-response curves to acetylcholine (ACh, 0.001-10 μmol/l) during phenylephrine (10 μmol/l)-induced contraction. As a result, overnight exposure of aortic rings to TNF-α resulted in significant blunted maximal relaxing responses (E(max)) to ACh compared with untreated rings (22 ± 4 vs. 82 ± 3%, respectively). IL-10 knockout mice treated with TNF-α showed significant impairment in ACh responses (E(max)) compared with C57BL/6 mice treated with TNF-α (51 ± 3 vs. 72 ± 3%, respectively). Western blot analysis showed that endothelial nitric oxide synthase (eNOS) expression was reduced by TNF-α in in vitro and in vivo experiments, whereas IL-10 restored the eNOS expression. In conclusion, the anti-inflammatory cytokine IL-10 prevents impairment in endothelium-dependent vasorelaxation caused by TNF-α by protecting eNOS expression.

T cells in ANCA-associated vasculitis: what can we learn from lesional versus circulating T cells?

Anti-neutrophil cytoplasmic antibody (ANCA) - associated vasculitis (AAV) is a life-threatening autoimmune disease characterized by an antibody-mediated glomerulonephritis and necrotizing vasculitis. Apart from antibodies, T cells are also involved in disease pathogenesis. This review stresses the hallmarks of T cell-mediated pathology in AAV and highlights the characteristics of lesional and circulating T cells in the immune response in AAV. Circulating effector T-cell populations are expanded and are in a persistent state of activation. Circulating regulatory T-cell subsets are less well characterized but seem to be impaired in function. Lesional effector T cells are present in granulomas, vasculitic lesions, and nephritis. Lesional T cells usually show pro-inflammatory properties and promote granuloma formation. Apart from T cells, dendritic cells are abundantly present at the sites of inflammation and locally orchestrate the immune response. Targeting the above-mentioned T cell-mediated disease mechanisms will potentially provide powerful therapeutic tools for AAV.

Nitric Oxide Inhibits Ultraviolet B-induced Murine Keratinocyte Apoptosis by Regulating Apoptotic Signaling Cascades

Cytotoxic effects of nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) are considered to be one of the major causes of inflammatory diseases. On the other hand, protective effects of NO on toxic insults-induced cellular damage/apoptosis have been demonstrated recently. Ultraviolet B (UVB)-induced apoptosis of epidermal keratinocytes leads to skin inflammation and photoageing. However, it has not been elucidated what kind of effects NO has on UVB-induced keratinocyte apoptosis. Thus, in the present study, we investigated the problem and demonstrated that NO from NO donor suppressed UVB-induced apoptosis of murine keratinocytes. In addition, NO significantly suppressed activities of caspase 3, caspase 8 and caspase 9 that had been upregulated by UVB radiation. NO also suppressed p53 expression that had been upregulated by UVB radiation and upregulated Bcl-2 expression that had been down-regulated by UVB radiation. These findings suggested that NO might suppress UVB-induced keratinocyte apoptosis by regulating apoptotic signaling cascades in p53, Bcl-2, caspase3, caspase 8 and caspase 9.

Janus faces of microglia in multiple sclerosis

Multiple sclerosis (MS) is the most common cause of neurological disability in young adults. The disease is characterized by inflammatory reactions, demyelination and axonal loss in the brain, spinal cord and optic nerves. Microglia seem to play an important role in the inflammatory processes in MS, since they are found in actively demyelinating lesions. Their role in the differentiation of T cells could led to the expansion of inflammation and tissue destruction. However, microglia are also involved in the termination of an inflammatory response and produce protective factors. To be able to therapeutically manipulate microglia, their exact function in the onset and development of MS needs to be clarified. This review provides an overview of the functions of the most important microglia-associated molecules in MS, being CD40, B7-1 and B7-2, interferon-gamma, tumor necrosis factor-alpha, chemokines, prostanoids, and nitric oxide.

N-acetylcysteine attenuates TNF-alpha-induced human vascular endothelial cell apoptosis and restores eNOS expression

The circulatory inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) is increased in pathological conditions, such as diabetes, which initiate or exacerbate vascular endothelial injury. Both nitric oxide (NO) and reactive oxygen species may play a dual role (i.e., inhibiting or promoting) in TNF-alpha-induced endothelial cell apoptosis. We investigated the effects of the antioxidant N-acetylcysteine on TNF-alpha-induced apoptosis in human vascular endothelial cell (cell line ECV304) apoptosis, NO production and lipid peroxidation. Cultured vascular endothelial cell (ECV304) were either not treated (control), or treated with TNF-alpha (40 ng/ml) alone or TNF-alpha in the presence of N-acetylcysteine at 30 mmol/l or 1 mmol/l, respectively, for 24 h. Cell viability was measured by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Cell apoptosis was assessed by flow cytometry. TNF-alpha-induced endothelial cell apoptosis was associated with increased inducible NO synthase but reduced endothelial NO synthase (eNOS) protein expression. NO production and the levels of the lipid peroxidation product malondialdehyde were concomitantly increased. Treatment with NAC at 30 mmol/l restored eNOS expression and further increased NO production as compared to TNF-alpha alone, resulting in improved cell viability and reduced apoptosis. This was accompanied by increased superoxide dismutase activity, increased glutathione peroxidase production and reduced malondialdehyde levels. N-acetylcysteine at 1 mmol/l, however, did not have significant effects on TNF-alpha-induced endothelial cell apoptosis and cell viability despite it slightly enhanced glutathione peroxidase production. N-acetylcysteine attenuation of TNF-alpha-induced human vascular endothelial cell apoptosis is associated with the restoration of eNOS expression.

Intraocular cytokine environment in active Behçet uveitis

PURPOSE

To determine cytokine profiles in aqueous humor and peripheral blood from patients with Behçet uveitis.

DESIGN

Prospective, experimental, and case-control study.

METHODS

Aqueous humor and peripheral blood samples from 24 patients with Behçet uveitis, 28 patients with other causes of endogenous uveitis, and 20 healthy subjects after uncomplicated cataract surgery were obtained. Cytokines (interferon gamma (IFN-gamma), interleukin [IL]-2, IL-4, IL-10, IL-12, IL-15, and tumor necrosis factor alpha (TNF-alpha)) were measured by enzyme-linked immunosorbent assay and compared between the uveitis groups.

RESULTS

Aqueous interferon gamma (IFN-gamma) levels were higher in patients with Behçet uveitis in contrast to higher concentrations of IL-4 in patients without Behçet uveitis. Aqueous levels of tumor necrosis factor alpha (TNF-alpha) were higher in patients with Behçet uveitis than in patients without Behçet uveitis. Aqueous and serum IL-10 were detected in all patients without Behçet uveitis, but were below detection limits in all patients with Behçet uveitis. Furthermore, IL-15 was exclusively increased in the aqueous humor of Behçet uveitis. The aqueous IL-2 or IL-12 levels were similar regardless of the presence of Behçet uveitis.

CONCLUSIONS

Our results showed that an extreme Th1 polarization, a high proinflammatory condition, a low immunosuppressive status, and the presence of natural killer (NK) or CD8+ T cell-activating cytokine were unique features in aqueous humor with Behçet uveitis, suggesting that different immunopathogenic mechanisms may be involved in the ongoing intraocular inflammation of Behçet uveitis.

Angiogenesis in a human neuroblastoma xenograft model: mechanisms and inhibition by tumour-derived interferon-gamma

Tumour progression in neuroblastoma (NB) patients correlates with high vascular index. We have previously shown that the ACN NB cell line is tumorigenic and angiogenic in immunodeficient mice, and that interferon-γ (IFN-γ) gene transfer dampens ACN tumorigenicity. As IFN-γ represses lymphocyte-induced tumour angiogenesis in various murine models and inhibits proliferation and migration of human endothelial cells, we have investigated the antiangiogenic activity of tumour-derived IFN-γ and the underlying mechanism(s). In addition, we characterised the tumour vasculature of the ACN xenografts, using the chick embryo chorioallantoic membrane assay. We show that the ACN/IFN-γ xenografts had a lower microvessel density and less in vivo angiogenic potential than the vector-transfected ACN/neo. The vascular channels of both xenografts were formed by a mixed endothelial cell population of murine and human origin, as assessed by the FICTION (fluorescence immunophenotyping and interphase cytogenetics) technique. With respect to ACN/neo, the ACN/IFN-γ xenografts showed more terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling-positive human and murine endothelial cells, suggesting that inhibition of angiogenesis by IFN-γ was dependent on the induction of apoptosis, likely mediated by nitric oxide. Once the dual origin of tumour vasculature is confirmed in NB patients, the xenograft model described here will prove useful in testing the efficacy of different antiangiogenic compounds.

JNK signaling pathway is a key modulator in cell death mediated by reactive oxygen and nitrogen species

c-Jun N-terminal kinase (JNK), or stress-activated protein kinase, is an important member of the mitogen-activated protein kinase superfamily, the members of which are readily activated by many environmental stimuli. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are important groups of free radicals that are capable of eliciting direct damaging effects or acting as critical intermediate signaling molecules, leading to oxidative and nitrosative stress and a series of biological consequences. Recently there has been an increasing amount of research interest focusing on the regulatory role of JNK activation in ROS-and RNS-induced cellular responses. In this review we will first summarize and discuss some recent findings regarding the signaling mechanisms of ROS-or RNS-mediated JNK activation. Second, we will talk about the role of JNK in ROS-or RNS-mediated cell death (both apoptosis and necrosis). Finally, we will analyze the emerging evidence for the involvement of ROS and RNS as mediators in tumor necrosis factor alpha-induced apoptosis. Taken together, the accumulating knowledge about the ROS/RNS-induced JNK signaling pathway has greatly advanced our understanding of the complex processes deciding the cellular responses to environmental stress.

Fundamental role of nitric oxide in neuritogenesis of PC12h cells

1 We investigated the neuritogenic action of nitric oxide (NO)-generating agents and their mechanisms of action in a subclone of rat pheochromocytoma, PC12h cells. 2 NO donors such as sodium nitroprusside (SNP, 0.05-1 microM), NOR1 (5-100 microM), NOR2 (5-20 microM), NOR3 (5-20 microM), NOR4 (5-100 microM), or S-nitroso-N-acetyl-DL-penicillamine (SNAP, 10-100 microM) significantly induced neurite outgrowth. 3 NOR4-induced neurite outgrowth was accompanied by expression of neurofilament 200 kDa subunit (NF200) protein, an axonal marker, and was significantly inhibited by an NO scavenger, a soluble GC inhibitor, and a PKG inhibitor: 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazole-1-oxyl-3-oxide (carboxy-PTIO, 20-100 microM), 1H-[1,2,4]oxadiazolo[4,3-a] quinoxalin-1-one (ODQ, 100 microM) and KT5823 (0.2-1 microM), respectively. 4 The intracellular cGMP concentration of cells was markedly increased by treatment with NOR4 (100 microM). 5 A mitogen-activated protein kinase (MAPK) kinase inhibitor, PD98059 (10-50 microM), abolished the NOR4-induced neurite outgrowth. In agreement with this observation, NOR4 did phosphorylate extracellular signal-regulated kinase (ERK) 1 and 2, substrates of MAPK kinase. 6 A membrane-permeable cGMP analog, 8-Br-cGMP (1 mM) also induced significant neurite outgrowth. The 8-Br-cGMP-induced neurite outgrowth was almost completely inhibited by both KT5823 (0.5 microM) and PD98059 (50 microM). Moreover, sustained ERK phosphorylation was observed in the 8-Br-cGMP-treated PC12h cells. 7 These results suggest that NO itself has the ability to induce neurite outgrowth and that NO-induced ERK activation involves the NO-cGMP-PKG signaling pathway in PC12h cells.

Effects of nitric oxide synthase inhibitor on acid aspiration-induced lung injury in rats

The current study was designed to determine the effects of nitric oxide synthase (NOS) in the development of acid aspiration-induced lung injury in rats. Hydrochloric acid (HCl, 0.1 N; 2 ml/kg) or normal saline (NS, 2 ml/kg) was instilled into the lung of anesthetized, ventilated Sprague-Dawley rats. NG-monomethyl-L-arginine (L-NMMA, 20 mg kg(-1)) and a selective inducible nitric oxide synthase (iNOS) inhibitor, ONO-1714 (0.1 and 0.3 mg kg(-1)), were used to block NOS. Bronchoalveolar lavage fluid (BALF) and wet and dry measurements of lung (W/D) were obtained 5h after HCl or NS instillation. Unlike the control group, rats instilled with HCl showed significant increases in total nuclear cell counts (NCC), neutrophil counts, concentrations of albumin, tumor necrosis factor-alpha (TNF-alpha), interleukine-6 (IL-6) and nitrites/nitrates (NO(x)) in BALF. These parameters were associated with the significantly increased W/D in the HCl group compared with the NS group. ONO-1714 (0.1 mg kg(-1)) significantly prevented the increases in all these parameters. Its inhibitory effects were superior to those of L-NMMA and 0.3 mg kg(-1) of ONO-1714. NOS plays an important role in the pathogenesis of acid aspiration-induced lung injury. Furthermore, selective iNOS inhibition at the optimal dose was most effective in improving lung injury induced by acid aspiration in rats.

Gene activation and protein expression following ischaemic stroke: strategies towards neuroprotection

Current understanding of the patho-physiological events that follow acute ischaemic stroke suggests that treatment regimens could be improved by manipulation of gene transcription and protein activation, especially in the penumbra region adjacent to the infarct. An immediate reduction in excitotoxicity in response to hypoxia, as well as the subsequent inflammatory response, and beneficial control of reperfusion via collateral revascularization near the ischaemic border, together with greater control over apoptotic cell death, could improve neuronal survival and ultimately patient recovery. Highly significant differences in gene activation between animal models for stroke by middle cerebral artery occlusion, and stroke in patients, may explain why current treatment strategies based on animal models of stroke often fail. We have highlighted the complexities of cellular regulation and demonstrated a requirement for detailed studies examining cell specific protective mechanisms after stroke in humans.

Ischemic proximal tubular injury primes mice to endotoxin-induced TNF-alpha generation and systemic release

Endotoxemia (LPS) can exacerbate ischemic tubular injury and acute renal failure (ARF). The present study tested the following hypothesis: that acute ischemic damage sensitizes the kidney to LPS-mediated TNF-alpha generation, a process that can worsen inflammation and cytotoxicity. CD-1 mice underwent 15 min of unilateral renal ischemia. LPS (10 mg/kg iv), or its vehicle, was injected either 45 min before, or 18 h after, the ischemic event. TNF-alpha responses were gauged 2 h post-LPS injection by measuring plasma/renal cortical TNF-alpha and renal cortical TNF-alpha mRNA. Values were contrasted to those obtained in sham-operated mice or in contralateral, nonischemic kidneys. TNF-alpha generation by isolated mouse proximal tubules (PTs), and by cultured proximal tubule (HK-2) cells, in response to hypoxia-reoxygenation (H/R), oxidant stress, antimycin A (AA), or LPS was also assessed. Ischemia-reperfusion (I/R), by itself, did not raise plasma or renal cortical TNF-alpha or its mRNA. However, this same ischemic insult dramatically sensitized mice to LPS-mediated TNF-alpha increases in both plasma and kidney (approximately 2-fold). During late reperfusion, increased TNF-alpha mRNA levels also resulted. PTs generated TNF-alpha in response to injury. Neither AA nor LPS alone induced an HK-2 cell TNF-alpha response. However, when present together, AA+LPS induced approximately two- to fivefold increases in TNF-alpha/TNF-alpha mRNA. We conclude that modest I/R injury, and in vitro HK-2 cell mitochondrial inhibition (AA), can dramatically sensitize the kidney/PTs to LPS-mediated TNF-alpha generation and increases in TNF-alpha mRNA. That ischemia can "prime" tubules to LPS response(s) could have potentially important implications for sepsis syndrome, concomitant renal ischemia, and for the induction of ARF.

Inflammatory processes in muscle injury and repair

Modified muscle use or injury can produce a stereotypic inflammatory response in which neutrophils rapidly invade, followed by macrophages. This inflammatory response coincides with muscle repair, regeneration, and growth, which involve activation and proliferation of satellite cells, followed by their terminal differentiation. Recent investigations have begun to explore the relationship between inflammatory cell functions and skeletal muscle injury and repair by using genetically modified animal models, antibody depletions of specific inflammatory cell populations, or expression profiling of inflamed muscle after injury. These studies have contributed to a complex picture in which inflammatory cells promote both injury and repair, through the combined actions of free radicals, growth factors, and chemokines. In this review, recent discoveries concerning the interactions between skeletal muscle and inflammatory cells are presented. New findings clearly show a role for neutrophils in promoting muscle damage soon after muscle injury or modified use. No direct evidence is yet available to show that neutrophils play a beneficial role in muscle repair or regeneration. Macrophages have also been shown capable of promoting muscle damage in vivo and in vitro through the release of free radicals, although other findings indicate that they may also play a role in muscle repair and regeneration through growth factors and cytokine-mediated signaling. However, this role for macrophages in muscle regeneration is still not definitive; other cells present in muscle can also produce the potentially regenerative factors, and it remains to be proven whether macrophage-derived factors are essential for muscle repair or regeneration in vivo. New evidence also shows that muscle cells can release positive and negative regulators of inflammatory cell invasion, and thereby play an active role in modulating the inflammatory process. In particular, muscle-derived nitric oxide can inhibit inflammatory cell invasion of healthy muscle and protect muscle from lysis by inflammatory cells in vivo and in vitro. On the other hand, muscle-derived cytokines can signal for inflammatory cell invasion, at least in vitro. The immediate challenge for advancing our current understanding of the relationships between muscle and inflammatory cells during muscle injury and repair is to place what has been learned in vitro into the complex and dynamic in vivo environment.

Enhancement of apoptosis by nitric oxide released from α-phenyl-tert-butyl nitrone under hyperthermic conditions

The aim of this study was to examine whether a neuroprotector, PBN (alpha-phenyl-tert-butyl nitrone), enhances apoptosis induced by hyperthermia, which generates superoxide (O2-) intracellularly, since the release of nitric oxide (NO) from PBN under oxidative stress has been reported. When human myelomonocytic lymphoma U937 cells were treated with hyperthermia (44 degrees C, 10 min) and PBN, an increase in the concentration of nitrite in the culture medium, and a decrease in the hyperthermia-induced production of O2- was observed. Imaging using a fluorescence dye for intracellular NO, diaminofluorescein-2 diacetate (DAF-2 DA), revealed the formation of NO in the apoptotic cells treated with hyperthermia and PBN combined. Apoptotic endpoints were significantly enhanced by the combined treatment: a decrease in mitochondrial trans-membrane potential, cleavage of Bid, release of cytochrome c, and activation of caspase-8 and -3. An increase in the intracellular Ca2+ concentration ([Ca2+]i), externalization of Fas, and decrease in Hsp70 and phosphorylated HSF1 were observed following the combined treatment. Furthermore, scavengers of NO an d ONOO- significantly inhibited the enhancement of apoptosis, the externalization of Fas and the increase in [Ca2+]i. These results suggest that, (1) NO is released from PBN by hyperthermia, and subsequently reacts with O2- to form ONOO-, (2) NO and ONOO- are involved in the enhancement of apoptosis through Fas-mitochondria-caspase and [Ca2+]i-dependent pathways, and (3) a decrease in Hsp70 and phosphorylated HSF1 also contributed to the enhancement of apoptosis.

Interferon alpha 2a down-regulates VEGF expression through PI3 kinase and MAP kinase signaling pathways

An earlier report demonstrated that interferon alpha (IFN-alpha) inhibited tumor growth and recurrence in an MHCC97 xenograft model in nude mice by suppressing tumor angiogenesis rather than by inhibiting tumor cell proliferation. However, the underlying molecular mechanism was not fully elucidated. In this study, we demonstrated that IFN-alpha 2a could down-regulate VEGF expression both in mRNA and in protein levels, as well as down-regulating HIF-1 alpha mRNA expression in MHCC97 cells in vitro. A cDNA micro array analysis followed by Northern and Western blot analysis revealed that PI3 kinase and MAP kinase signaling pathways might be inhibited by IFN-alpha 2a. Blocking the function of IFN-alpha receptor with a specific peptide could eliminate the inhibitory effects of IFN-alpha 2a on VEGF expression. In addition, wortmannin and PD098059, respective inhibitors of the PI3 kinase and the MAP kinase signaling pathways, when used independently or in combination, could also down-regulate the VEGF synthesis and secretion in a similar pattern of IFN-alpha 2a. These observations may lead to the conclusion that IFN-alpha 2a could suppress VEGF synthesis and secretion by down-regulating HIF-1 alpha expression, via inhibition of the PI3 kinase and/or the MAP kinase signaling pathways.

Wegener's granulomatosis is associated with organ-specific antiendothelial cell antibodies

BACKGROUND

Antiendothelial cell antibodies (AECA), usually detected using human umbilical vein endothelial cells (HUVEC), are frequently observed in systemic vasculitis, but their pathogenic role is unclear. Heterogeneity of endothelial cells necessitates use of clinically relevant endothelial cells for elucidation of the role of AECA in systemic vasculitis involving small blood vessels of specific organs.

METHODS

Human endothelial cells were isolated from normal tissue specimens from the nose, kidney, lung, liver, and umbilical vein. Using flow cytometry, AECA were detected against both unstimulated and cytokine-stimulated [tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma)] endothelial cells. Functional capacity of AECA was determined by complement fixation assay. Sera from patients with Wegener's granulomatosis (16), limited Wegener's granulomatosis (8), renal limited disease (4), microscopic polyangiitis (MPA) (5), rheumatoid arthritis (10), and systemic lupus erythematosus (SLE) (9), and from healthy controls (20) were analyzed.

RESULTS

Compared with controls (1) Wegener's granulomatosis is significantly associated with noncytotoxic AECA that selectively bind surface antigens on unstimulated nasal, kidney, and lung endothelial cells; (2) binding of Wegener's granulomatosis AECA to kidney and nasal endothelial cells in particular was lost upon treatment with IFN-gamma and TNF-alpha; (3) the two cytokines per se were cytotoxic (30%) to nasal and lung endothelial cells and lysis was further increased (60%) by addition of systemic vasculitis serum; and (4) Wegener's granulomatosis serum caused agglutination of cytokine-stimulated nasal endothelial cells.

CONCLUSION

Based on these findings we suggest that AECA may be one factor involved in the initiation of Wegener's granulomatosis. Antigen identification and elucidation of the pathogenic roles of AECA and inflammatory cytokines in systemic vasculitis using these cells will be particularly important.

Is damage in central nervous system due to inflammation?

The aim of this work was to review the inflammatory factors involved in central nervous system (CNS) inflammation and the damage associated to their participation in an inflammatory disease of CNS, multiple sclerosis in humans and experimental allergic encephalomyelitis in the murine model. Inflammation has an important repairing function, nevertheless frequently in the CNS inflammation is the cause of damage and it does not fulfill this repairing function as it happens in other compartments of the body. The inflammatory response in the CNS involves the participation of different cellular types of the immune system (macrophages, mast cells, T and B lymphocytes, dendritic cells) and resident cells of the CNS (microglia, astrocytes, neurons), adhesion molecules, cytokines and chemokines among other proteic components. During neuroinflammation chemotaxis is an important event in the recruitment of cells to the CNS. The lymphocyte recruitment implies the presence of chemokines and chemokine receptors, the expression of adhesion molecules, the interaction between lymphocytes and the bloodbrain barrier (BBB) endothelium, and finally their passage through the BBB to arrive at the site of inflammation. If this process is not controlled, is prolonged, inflammation loses its repairing function and can be the cause of damage. Usually neuroinflammation has the tendency to decline to damage, which would explain most of the CNS pathologies.

Role of human heme oxygenase-1 in attenuating TNF-alpha-mediated inflammation injury in endothelial cells

Heme oxygenase (HO) is the rate-limiting enzyme in the formation of bilirubin, an antioxidant, and carbon monoxide (CO), a cell cycle modulator and a vasodilator. Cyclooxygenase (COX) is a hemeprotein that catalyzes the conversion of arachidonic acid (AA) to various prostanoids, which play an important role in the regulation of vascular endothelial function in normal and disease states. The influence of suppression or overexpression of HO isoforms on COX expression and synthesis of prostanoids is of considerable physiological importance. Consequently, the goal of the present study was to determine whether the heme-HO system regulates COX enzyme expression and activity in vascular endothelial cells in the absence and presence of TNF-alpha (100 ng/ml). Endothelial cells stably transfected with the retrovirus containing the human HO-1 gene exhibited a several-fold increase in HO-1 protein levels, which was accompanied by an increase in HO activity and a marked decrease in PGE(2) and 6-keto PGF(1alpha) levels. We also assessed the effect of retrovirus-mediated HO-1 gene transfer in the sense and antisense orientation on HO-1 expression and cell cycle progression in human endothelial cells. The levels of CO and HO activity were increased in cells transduced with the HO-1 sense and were greatly suppressed in cells transduced with HO-1 antisense as compared to control sham-transduced cells (P < 0.05). The percentage of the G(1)-phase in cells transduced with HO-1 significantly increased (41.4% +/- 9.1) compared with control endothelial cells (34.8% +/- 4.9). We measured COX activity by determining the levels of PGI(2) and PGE(2). The levels of PGI(2) decreased in cells transduced with HO-1 sense and increased in cells transduced with HO-1 in antisense orientation. The expression of p27 was also studied and showed a marked decrease in cells transduced with HO-1 sense and a marked increase in the HO-1 antisense transduced cells. Cell cycle analysis of endothelial cell DNA distributions indicated that the TNF-alpha-induced decrease in the proportion of G(1)-phase cells and increase in apoptotic cells in control cultures could be abrogated by transfection with HO-1 in the sense orientation. Tin mesoporphyrin (SnMP) reversed the protective effect of HO-1. These results demonstrate that overexpressing HO-1 mitigated the TNF-alpha-mediated changes in cell cycle progression and apoptosis, perhaps by a decrease in the levels of COX activity.

Immunobiologic analysis of arterial tissue in Buerger's disease

INTRODUCTION

the cause of thromboangiitis obliterans (TAO) still remains unknown. We have reported that immunologic injury associated with T lymphocytes infiltration might be the initial etiologic mechanism in TAO. The present study was undertaken to examine further the mechanism of immune injury.

METHODS

arterial walls affected by TAO were obtained from eight patients with eight non-pulsatile arteries and one patent artery. Immunohistochemical and TUNEL studies were performed for phenotyping of the infiltrating cells with CD4 (helper T cell), CD8 (cytotoxic T cell), CD56 (natural killer cell), and CD68 (macrophage), for identification of cell activation with VCAM-1 and i -NOS, for the presence of cell death with TUNEL analysis, and for inflammatory cytokine detection with RT-PCR.

RESULTS

the characteristic features were luminal obliteration, together with a varying degree of recanalization. T cells infiltrated mainly in thrombus, intima, and adventita. Among infiltrating cells, CD4 T cells greatly outnumbered CD8 cells. VCAM-1 and i -NOS were expressed in endothelial cells around the intima (patent segment) or vaso vasorum (occluded segment). Endothelial cells in vaso vasorum stained positive with TUNEL. Interferon-gamma mRNA was detected in two specimens.

CONCLUSIONS

our results suggest that T cell mediated immune inflammation is a significant event in the development of TAO.

Cholesterol attenuates linoleic acid-induced endothelial cell activation

Vascular endothelial cell activation and dysfunction are critical early events in atherosclerosis. Even though very low or high levels of cholesterol can compromise cellular functions, cholesterol is a critical membrane component and may protect the vascular endothelium from oxidative stress and polyunsaturated fatty acid-mediated inflammatory responses. We have previously shown that the parent omega-6 fatty acid linoleic acid can markedly activate vascular endothelial cells. We now propose that membrane cholesterol can modify and inhibit linoleic acid-mediated endothelial cell dysfunction. To test this hypothesis, pulmonary artery endothelial cells were incubated with cholesterol (0 to 100 micromol/L) for 24 hours and then treated with 90 micromol/L of linoleic acid (18:2n-6) for 6 to 24 hours. In control cells, treatment with linoleic acid reduced intracellular glutathione levels and induced the DNA binding activity of nuclear factor-kappaB (NF-kappaB) leading to the upregulation of interleukin-6 (IL-6). In addition, the expression of endothelial nitric oxide synthase (eNOS) was altered, with linoleic acid increasing eNOS activity. In contrast, enrichment with cholesterol enhanced glutathione levels and reduced the linoleic acid-induced activation of NF-kappaBand the production of IL-6. Prior exposure to 50 micromol/L cholesterol also prevented the fatty acid-induced increase in eNOS activation. Cholesterol loading activated peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a nuclear receptor that can decrease inflammatory responses. Furthermore, the PPAR-gamma agonist thiazolidinedione markedly downregulated the NF-kappaB activation mediated by linoleic acid. Our data suggest that signaling pathways linked to endothelial cell activation by prooxidant and proinflammatory insults may be influenced by cellular cholesterol levels.

Effect of lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on the susceptibility to Listeria infection

We studied the effect of lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the susceptibility to Listeria infection of offspring in C57BL /6NCji mice. The offspring were nursed by TCDD-treated dams and exposed to TCDD from birth to weaning via milk. The exposure had little effect on the weights of immune organs and the spleen or the thymus cell population in the dams and offspring, but it enhanced the production of tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) in the serum after Listeria infection. The clearance of Listeria monocytogenes from the spleen was impaired in the off-spring. These results suggest that the exposure to TCDD of the offspring via milk disrupted the host resistance of the offspring, even though the main immune parameters were unchanged.