Anoxia-hyperoxia induces monocyte-derived interleukin-8

Strategies to attenuate maladaptive inflammatory response associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) initiates an intense inflammatory response due to various factors: conversion from pulsatile to laminar flow, cold cardioplegia, surgical trauma, endotoxemia, ischemia-reperfusion injury, oxidative stress, hypothermia, and contact activation of cells by the extracorporeal circuit. Redundant and overlapping inflammatory cascades amplify the initial response to produce a systemic inflammatory response, heightened by coincident activation of coagulation and fibrinolytic pathways. When unchecked, this inflammatory response can become maladaptive and lead to serious postoperative complications. Concerted research efforts have been made to identify technical refinements and pharmacologic interventions that appropriately attenuate the inflammatory response and ultimately translate to improved clinical outcomes. Surface modification of the extracorporeal circuit to increase biocompatibility, miniaturized circuits with sheer resistance, filtration techniques, and minimally invasive approaches have improved clinical outcomes in specific populations. Pharmacologic adjuncts, including aprotinin, steroids, monoclonal antibodies, and free radical scavengers, show real promise. A multimodal approach incorporating technical, circuit-specific, and pharmacologic strategies will likely yield maximal clinical benefit.

Impact of N-Acetyl Cysteine (NAC) on Tuberculosis (TB) Patients-A Systematic Review

Sustained TB infection overproduces reactive oxygen species (ROS) as a host defense mechanism. Research shows ROS is destructive to lung tissue. Glutathione (GSH) neutralizes ROS, although it is consumed. NAC is a precursor of GSH synthesis, and administering an appropriate dose of NAC to patients with respiratory conditions may enhance lung recovery and replenish GSH. The present review searched for articles reporting on the effects of NAC in TB treatment from 1960 to 31 May 2022. The PICO search strategy was used in Google Scholar, PubMed, SciFinder, and Wiley online library databases. The COVIDENCE tool was used to delete inappropriate content. We eventually discovered five clinical trials, one case report, seven reviews, in vitro research, and four experimental animal studies from the twenty-four accepted articles. The use of NAC resulted in increased GSH levels, decreased treatment time, and was safe with minimal adverse events. However, the evidence is currently insufficient to estimate the overall effects of NAC, thus the study warrants more NAC clinical trials to demonstrate its effects in TB treatment.

Loss of CX3CR1 augments neutrophil infiltration into cochlear tissues after acoustic overstimulation

The cochlea, the sensory organ for hearing, has a protected immune environment, segregated from the systemic immune system by the blood-labyrinth barrier. Previous studies have revealed that acute acoustic injury causes the infiltration of circulating leukocytes into the cochlea. However, the molecular mechanisms controlling immune cell trafficking are poorly understood. Here, we report the role of CX3CR1 in regulating the entry of neutrophils into the cochlea after acoustic trauma. We employed B6.129P-Cx3cr1^tm1Litt /J mice, a transgenic strain that lacks the gene, Cx3cr1, for coding the fractalkine receptor. Our results demonstrate that lack of Cx3cr1 results in the augmentation of neutrophil infiltration into cochlear tissues after exposure to an intense noise of 120 dB SPL for 1 hr. Neutrophil distribution in the cochlea is site specific, and the infiltration level is positively associated with noise intensity. Moreover, neutrophils are short lived and macrophage phagocytosis plays a role in neutrophil clearance, consistent with typical neutrophil dynamics in inflamed non-cochlear tissues. Importantly, our study reveals the potentiation of noise-induced hearing loss and sensory cell loss in Cx3cr1^-/- mice. In wild-type control mice (Cx3cr1^+/+ ) exposed to the same noise, we also found neutrophils. However, neutrophils were present primarily inside the microvessels of the cochlea, with only a few in the cochlear tissues. Collectively, our data implicate CX3CR1-mediated signaling in controlling neutrophil migration from the circulation into cochlear tissues and provide a better understanding of the impacts of neutrophils on cochlear responses to acoustic injury.

Cell death induction (extrinsic versus intrinsic apoptotic pathway) by intestinal ischemia-reperfusion injury in rats is time-depended

PURPOSE

We investigate the mechanism of intestinal cell apoptosis and its relation to the time of reperfusion in a rat model of intestinal ischemia-reperfusion (IR).

METHODS

Rats were divided into 4 groups: Sham-24 and Sham-48 rats underwent laparotomy without an intentional ischemic intervention and were sacrificed 24 or 48 h hours later; IR-24 and IR-48 rats underwent occlusion of SMA and portal vein for 20 min followed by 24 or 48 h of reperfusion, respectively. Park's injury score, cell proliferation and apoptosis were determined at sacrifice. Proliferation and apoptosis-related gene and protein expression were determined using Real-Time PCR, Western Blot and Immunohistochemistry.

RESULTS

IR-24 rats demonstrated a strong increase in cell apoptosis along with an elevated Bax and decreased Bcl-2 expression and a decrease in cell proliferation (vs Sham-24). IR-48 group showed an increase in cell proliferation and a decrease in cell apoptosis compared to IR-24 animals. IR-48 rats demonstrated an increase in apoptotic rate that was accompanied by greater TNF-α mRNA, Fas mRNA and FasL mRNA compared to Sham-48 animals.

CONCLUSION

While cell apoptosis in IR-24 rats is regulated mainly by intrinsic apoptotic pathway, 48 h followed ischemia extrinsic apoptotic pathway is responsible for pro-apoptotic effects of IR injury.

Human Red Blood Cells Modulate Cytokine Expression in Monocytes/Macrophages Under Anoxic Conditions

In the bone marrow (BM) hematopoietic niche, the oxygen tension is usually very low. Such condition affects stem and progenitor cell proliferation and differentiation and, at cellular level regulates hematopoietic growth factors, chemokines and adhesion molecules expression. In turn, these molecules affect the proliferation and maturation of other cellular components of the niche. Due to the complexity of the system we started the in vitro investigations of the IL-6, IL-8, TNFα cytokines expression and the vascular endothelial growth factor (VEGF), considered key mediators of the hematopoietic niche, in human macrophages and macrophage cell line. Since in the niche the oxygen availability is mediated by red blood cells (RBCs), we have influenced the anoxic cell cultures by the administration of oxygenated or deoxygenated RBCs (deoxy RBCs). The results reported in this brief paper show that the presence of RBCs up-regulates IL-8 mRNA while IL-6 and VEGF mRNA expression appears down-regulated. This does not occur when deoxy RBCs are used. Moreover, it appears that the administration of RBCs leads to an increase of TNFα expression levels in MonoMac 6 (MM6). Interestingly, the modulation of these factors likely occurs in a hypoxia-inducible factor-1α (HIF-1α) independent manner. Considering the role of oxygen in the hematopoietic niche further studies should explore these preliminary observations in more details.

Hypoxia-inducible factors not only regulate but also are myeloid-cell treatment targets

Hypoxia describes limited oxygen availability at the cellular level. Myeloid cells are exposed to hypoxia at various bodily sites and even contribute to hypoxia by consuming large amounts of oxygen during respiratory burst. Hypoxia-inducible factors (HIFs) are ubiquitously expressed heterodimeric transcription factors, composed of an oxygen-dependent α and a constitutive β subunit. The stability of HIF-1α and HIF-2α is regulated by oxygen-sensing prolyl-hydroxylases (PHD). HIF-1α and HIF-2α modify the innate immune response and are context dependent. We provide a historic perspective of HIF discovery, discuss the molecular components of the HIF pathway, and how HIF-dependent mechanisms modify myeloid cell functions. HIFs enable myeloid-cell adaptation to hypoxia by up-regulating anaerobic glycolysis. In addition to effects on metabolism, HIFs control chemotaxis, phagocytosis, degranulation, oxidative burst, and apoptosis. HIF-1α enables efficient infection defense by myeloid cells. HIF-2α delays inflammation resolution and decreases antitumor effects by promoting tumor-associated myeloid-cell hibernation. PHDs not only control HIF degradation, but also regulate the crosstalk between innate and adaptive immune cells thereby suppressing autoimmunity. HIF-modifying pharmacologic compounds are entering clinical practice. Current indications include renal anemia and certain cancers. Beneficial and adverse effects on myeloid cells should be considered and could possibly lead to drug repurposing for inflammatory disorders.

Cancer cachexia has many symptoms but only one cause: anoxia

During nearly 100 years of research on cancer cachexia (CC), science has been reciting the same mantra: it is a multifactorial syndrome. The aim of this paper is to show that the symptoms are many, but they have a single cause: anoxia. CC is a complex and devastating condition that affects a high proportion of advanced cancer patients. Unfortunately, it cannot be reversed by traditional nutritional support and it generally reduces survival time. It is characterized by significant weight loss, mainly from fat deposits and skeletal muscles. The occurrence of cachexia in cancer patients is usually a late phenomenon. The conundrum is why do similar patients with similar tumors, develop cachexia and others do not? Even if cachexia is mainly a metabolic dysfunction, there are other issues involved such as the activation of inflammatory responses and crosstalk between different cell types.  The exact mechanism leading to a wasting syndrome is not known, however there are some factors that are surely involved, such as anorexia with lower calorie intake, increased glycolytic flux, gluconeogenesis, increased lipolysis and severe tumor hypoxia. Based on this incomplete knowledge we put together a scheme explaining the molecular mechanisms behind cancer cachexia, and surprisingly, there is one cause that explains all of its characteristics: anoxia.  With this different view of CC we propose a treatment based on the physiopathology that leads from anoxia to the symptoms of CC.  The fundamentals of this hypothesis are based on the idea that CC is the result of anoxia causing intracellular lactic acidosis. This is a dangerous situation for cell survival which can be solved by activating energy consuming gluconeogenesis. The process is conducted by the hypoxia inducible factor-1α. This hypothesis was built by putting together pieces of evidence produced by authors working on related topics.

Transcriptome analysis defines myocardium gene signatures in children with ToF and ASD and reveals disease-specific molecular reprogramming in response to surgery with cardiopulmonary bypass

BACKGROUND

Tetralogy of Fallot (ToF) and Atrial Septal Defects (ASD) are the most common types of congenital heart diseases and a major cause of childhood morbidity and mortality. Cardiopulmonary bypass (CPB) is used during corrective cardiac surgery to support circulation and heart stabilization. However, this procedure triggers systemic inflammatory and stress response and consequent increased risk of postoperative complications. The aim of this study was to define the molecular bases of ToF and ASD pathogenesis and response to CPB and identify new potential biomarkers.

METHODS

Comparative transcriptome analysis of right atrium specimens collected from 10 ToF and 10 ASD patients was conducted before (Pre-CPB) and after (Post-CPB) corrective surgery. Total RNA isolated from each sample was individually hybridized on Affymetrix HG-U133 Plus Array Strips containing 38,500 unique human genes. Differences in the gene expression profiles and functional enrichment/network analyses were assessed using bioinformatic tools. qRT-PCR analysis was used to validate gene modulation.

RESULTS

Pre-CPB samples showed significant differential expression of a total of 72 genes, 28 of which were overexpressed in ToF and 44 in ASD. According to Gene Ontology annotation, the mostly enriched biological processes were represented by matrix organization and cell adhesion in ToF and by muscle development and contractility in ASD specimens. GSEA highlighted the specific enrichment of hypoxia gene sets in ToF samples, pointing to a role for hypoxia in disease pathogenesis. The post-CPB myocardium exhibited significant alterations in the expression profile of genes related to transcription regulation, growth/apoptosis, inflammation, adhesion/matrix organization, and oxidative stress. Among them, only 70 were common to the two disease groups, whereas 110 and 24 were unique in ToF and ASD, respectively. Multiple functional interactions among differentially expressed gene products were predicted by network analysis. Interestingly, gene expression changes in ASD samples followed a consensus hypoxia profile.

CONCLUSION

Our results provide a comprehensive view of gene reprogramming in right atrium tissues of ToF and ASD patients before and after CPB, defining specific molecular pathways underlying disease pathophysiology and myocardium response to CPB. These findings have potential translational value because they identify new candidate prognostic markers and targets for tailored cardioprotective post-surgical therapies.

Monocytes and Macrophages in Cancer: Unsuspected Roles

The behavior of cancer is undoubtedly affected by stroma. Macrophages belong to this microenvironment and their presence correlates with reduced survival in most cancers. After a tumor-induced "immunoediting", these monocytes/macrophages, originally the first line of defense against tumor cells, undergo a phenotypic switch and become tumor-supportive and immunosuppressive.The influence of these tumor-associated macrophages (TAMs) on cancer is present in all traits of carcinogenesis. These cells participate in tumor initiation and growth, migration, vascularization, invasion and metastasis. Although metastasis is extremely clinically relevant, this step is always reliant on the angiogenic ability of tumors. Therefore, the formation of new blood vessels in tumors assumes particular importance as a limiting step for disease progression.Herein, the once unsuspected roles of macrophages in cancer will be discussed and their importance as a promising strategy to treat this group of diseases will be reminded.

Enhanced interleukin-8 production in mononuclear cells in severe pediatric obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease, metabolic disorders, and cognitive dysfunction. Current thinking links chronic intermittent hypoxia (CIH) with oxidative stress and systemic inflammation. However, the sequence of events leading to the morbidities associated with OSA is poorly understood in children. Monocytes are known to be altered by chronic hypoxia. Thus in this prospective study, we investigated inflammatory cytokine profiles from cultures of peripheral blood mononuclear cells (PBMC) obtained from children with severe OSA and sleep-related CIH.

Methods

Ten children with OSA (cases) and 5 age-matched children without OSA (controls) were recruited for study. Samples of plasma and PBMC were obtained before and after adenotonsillectomy. The levels of the inflammatory cytokines, interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12p70, and tumor necrosis factor-α (TNFα), were measured in both plasma and ex vivo culture supernatants of PBMC incubated with lipopolysaccharide (LPS) using the cytometric bead assay.

Results

Upon activation of PBMC by LPS, the levels of IL-8 in the culture supernatants from cases were threefold higher than in controls. The levels of the other cytokines including IL-1β, IL-6, and TNFα, in culture supernatant of PBMC from cases showed no difference from controls; nor were there significant differences in plasma cytokine levels.

Conclusion

We speculate that in young children with sleep-related CIH, an enhanced production capacity of IL-8 precedes the development of systemic inflammatory markers. Future work should evaluate IL-8 production capacity as a potential biomarker for OSA severity.

Mutually Supportive Mechanisms of Inflammation and Vascular Remodeling

Chronic inflammation is often accompanied by angiogenesis, the development of new blood vessels from existing ones. This vascular response is a response to chronic hypoxia and/or ischemia, but is also contributory to the progression of disorders including atherosclerosis, arthritis, and tumor growth. Proinflammatory and proangiogenic mediators and signaling pathways form a complex and interrelated network in these conditions, and many factors exert multiple effects. Inflammation drives angiogenesis by direct and indirect mechanisms, promoting endothelial proliferation, migration, and vessel sprouting, but also by mediating extracellular matrix remodeling and release of sequestered growth factors, and recruitment of proangiogenic leukocyte subsets. The role of inflammation in promoting angiogenesis is well documented, but by facilitating greater infiltration of leukocytes and plasma proteins into inflamed tissues, angiogenesis can also propagate chronic inflammation. This review examines the mutually supportive relationship between angiogenesis and inflammation, and considers how these interactions might be exploited to promote resolution of chronic inflammatory or angiogenic disorders.

Vascular endothelial growth factor signaling in hypoxia and inflammation

Infection, cancer and cardiovascular diseases are the major causes for morbidity and mortality in the United States according to the Center for Disease Control. The underlying etiology that contributes to the severity of these diseases is either hypoxia induced inflammation or inflammation resulting in hypoxia. Therefore, molecular mechanisms that regulate hypoxia-induced adaptive responses in cells are important areas of investigation. Oxygen availability is sensed by molecular switches which regulate synthesis and secretion of growth factors and inflammatory mediators. As a consequence, tissue microenvironment is altered by re-programming metabolic pathways, angiogenesis, vascular permeability, pH homeostasis to facilitate tissue remodeling. Hypoxia inducible factor (HIF) is the central mediator of hypoxic response. HIF regulates several hundred genes and vascular endothelial growth factor (VEGF) is one of the primary target genes. Understanding the regulation of HIF and its influence on inflammatory response offers unique opportunities for drug development to modulate inflammation and ischemia in pathological conditions.

Monocytes in sterile inflammation: recruitment and functional consequences

Monocytes play an important role in initiating innate immune responses. Three subsets of these cells have been defined in mice including classical, nonclassical and intermediate monocytes. Each of these cell types has been extensively studied for their role in infectious diseases. However, their role in sterile injury as occurs during ischemia-reperfusion injury, atherosclerosis, and trauma has only recently been the focus of investigations. Here, we review mechanisms of monocyte recruitment to sites of sterile injury, their modes of action, and their effect on disease outcome in murine models with some references to human studies. Therapeutic strategies to target these cells must be developed with caution since each monocyte subset is capable of mediating either anti- or pro-inflammatory effects depending on the setting.

Effects of albumin and synthetic polypeptide-coated oxygenators on IL-1, IL-2, IL-6, and IL-10 in open heart surgery

BACKGROUND

In this study, we have tried to demonstrate the effects of coating style used in oxygenators on various hematologic and clinical parameters.

MATERIALS AND METHODS

Twenty-seven patients were included in the study, who had undergone operations because of elective coronary artery disease. Albumin-coated oxygenator was used in Group I. In Group II, a synthetic polypeptide-coated oxygenator was used. C1-inhib (complement), C3c, C4, interleukins (IL-1β, IL2, IL-6, IL-10), and tumor necrosis factor alpha (TNF-α) levels were examined at four different time intervals. Hemoglobin, hematocrit, leukocyte and platelet counts, drainage, and transfused blood volumes were analyzed.

RESULTS

Albumin levels were significantly lower in Group I than those in Group II 5 minutes after the removal of the cross-clamp. Twenty-four hours after the surgery, Group I patients also had a significantly higher white blood cell count compared to Group II patients. TNF-α levels in Group I were always expressed in considerably higher amounts than those in Group II. IL-6 levels were significantly higher in Group I, but IL-10 levels were observed to be higher in Group II (p < 0.05).

CONCLUSION

Synthetic polypeptide-coated advanced technology, which employed oxygenators, had an important attenuator effect on acute phase reactants and also on the inflammatory response.

Hypoxia: how does the monocyte-macrophage system respond to changes in oxygen availability?

Hypoxia is an important feature of inflamed tissue, such as the RA joint. Activated monocytes/macrophages and endothelial cells play a pivotal role in the pathogenesis of RA, implicated in the mechanism of inflammation and erosion. During development, myeloid progenitor cells sequentially give rise to monoblasts, promonocytes, and monocytes that are released from the bone marrow into the bloodstream. After extravasation, monocytes differentiate into long-lived, tissue-specific macrophages or DCs. The effect of different oxygen concentrations experienced by these cells during maturation represents a novel aspect of this developmental process. In inflamed joint tissue, the microvascular architecture is highly dysregulated; thus, efficiency of oxygen supply to the synovium is poor. Therefore, invading cells must adapt instantaneously to changes in the oxygen level of the microenvironment. Angiogenesis is an early event in the inflammatory joint, which is important in enabling activated monocytes to enter via endothelial cells by active recruitment to expand the synovium into a "pannus", resulting in cartilage degradation and bone destruction. The increased metabolic turnover of the expanding synovial pannus outpaces the dysfunctional vascular supply, resulting in hypoxia. The abnormal bioenergetics of the microenvironment further promotes synovial cell invasiveness. In RA, joint hypoxia represents a potential threat to cell function and survival. Notably, oxygen availability is a crucial parameter in the cellular energy metabolism, itself an important factor in determining the function of immune cells.

Recent advances in underlying pathologies provide insight into interleukin-8 expression-mediated inflammation and angiogenesis

Interleukin-8 has long been recognized to have anti-inflammatory activity, which has been established in various models of infection, inflammation, and cancer. Several cell types express the receptor for the cytokine IL-8 and upon its recognition produce molecules that are active both locally and systemically. Many different types of cells, in particular monocytes, neutrophils, epithelial, fibroblast, endothelial, mesothelial, and tumor cells, secrete IL-8. Increased expression of IL-8 and/or its receptors has been characterized in many chronic inflammatory conditions, including psoriasis, ARDS, COPD, and RA as well as many cancers, and its upregulation often correlates with disease activity. IL-8 constitutes the CXC class of chemokines, a potent chemoattractant and activator of neutrophils and other immune cells. It is a proangiogenic cytokine that is overexpressed in many human cancers. Therefore, inhibiting the effects of IL-8 signaling may be a significant therapeutic intervention.

Effects of interleukin-8 on estradiol and progesterone production by bovine granulosa cells from large follicles and progesterone production by luteinizing granulosa cells in culture

Interleukin 8 (IL-8) is a chemoattractant involved in the recruitment and activation of neutrophils and is associated with the ovulate process. We examined the possible role of IL-8 in steroid production by bovine granulosa cells before and after ovulation. The concentration of IL-8 in the follicular fluid of estrogen-active dominant (EAD) and pre-ovulatory follicles (POF) was higher than that of small follicles (SF). CXCR1 mRNA expression was higher in the granulosa cells of EAD and POF than that of SF. In contrast, CXCR2 mRNA expression was lower in granulosa cells of EAD and POF than in SF. IL-8 inhibited estradiol (E2) production in follicle-stimulating hormone (FSH)-treated granulosa cells at 48 h of culture. IL-8 also suppressed CYP19A1 mRNA expression in FSH-treated granulosa cells. IL-8 stimulated progesterone (P4) production in luteinizing hormone (LH)-treated granulosa cells at 48 h of culture. Although IL-8 did not alter the expression of genes associated with P4 production, it induced StAR protein expression in LH-treated granulosa cells. The expression of CXCR1 mRNA in corpus luteum (CL) did not change during the luteal phase. In contrast, the expression of CXCR2 mRNA in middle CL was significantly higher than in early and regression CL during the luteal phase. In luteinizing granulosa cells, an in vitro model of granulosa cell luteinization, CXCR2 mRNA expression was downregulated, whereas CXCR1 mRNA expression was unchanged. IL-8 also stimulated P4 production in luteinizing granulosa cells. These data provide evidence that IL-8 functions not only as a chemokine, but also act as a regulator of steroid synthesis in granulosa cells to promote luteinization after ovulation.

The protective mechanism of ligustrazine against renal ischemia/reperfusion injury

BACKGROUND

Ischemia/reperfusion (I/R) injury is unavoidable in renal transplantation, and represents an additional risk factor for the late renal allograft failure. Our study focused on the effects of ligustrazine on oxidative stress, apoptosis, neutrophils recruitment, the expression of proinflammatory mediators and adhesion molecules caused by renal I/R injury.

MATERIALS AND METHODS

Renal warm I/R was induced in male C57BL/6 mice by clamping the left renal artery and vein non-traumatically. Group I was sham-operated animals; group II, nontreated animals; and group III, ligustrazine-treated animals (80 mg/kg, i.p. 30 min before I/R). Mice were sacrificed 4 and 24h post reperfusion. The effects of ligustrazine on oxidative stress, neutrophils recruitment, proinflammatory mediators, and adhesion molecules caused by renal I/R injury were assayed.

RESULTS

Ligustrazine pretreatment attenuated dramatically the injuries in mice kidneys caused by warm I/R (histological scores of untreated versus treated, 4.2 ± 0.4 versus 0.9 ± 0.3; P<0.01). Administration of ligustrazine significantly reduced myeloperoxidase (MPO) activity by 38.6% and decreased malondialdehye (MDA) level by 19.2%, while superoxide dismutase (SOD) activity increased by 39.6% (P<0.01), suggesting an effective reduction of oxidative stress following ligustrazine treatment. Moreover, ligustrazine also inhibited cell apoptosis, abrogated neutrophils recruitment, and suppressed the over expression of TNF-α and ICAM-1.

CONCLUSIONS

In conclusion, ligustrazine protects murine kidney from warm ischemia/reperfusion injury, probably via reducing oxidative stress, inhibiting cell apoptosis, decreasing neutrophils infiltration, and suppressing the overexpression of TNF-α and ICAM-1 levels.

The hypoxic synovial environment regulates expression of vascular endothelial growth factor and osteopontin in juvenile idiopathic arthritis

OBJECTIVE

Synovial angiogenesis, a critical determinant of juvenile idiopathic arthritis (JIA) pathogenesis, is sustained by various mediators, including vascular endothelial growth factor (VEGF) and osteopontin (OPN). We characterized the contribution of the local hypoxic environment to VEGF and OPN production by monocytic cells recruited to the synovium in JIA.

METHODS

Paired synovial fluid (SF) and peripheral blood (PB) samples were collected from 20 patients with JIA. Mononuclear cells (MC) were isolated, and monocytic cells were purified by adherence, maintained in a hypoxic environment, or subjected to reoxygenation. VEGF and OPN protein concentrations were tested in SF, plasma, and culture supernatants by ELISA, and mRNA expression was assessed in freshly purified and cultured cells by reverse transcriptase-polymerase chain reaction. Synovial tissue was obtained at synovectomy from 4 patients with JIA, and analyzed by immunohistochemistry for VEGF, OPN, CD68, and hypoxia-inducible factor-1alpha (HIF-1alpha).

RESULTS

VEGF mRNA expression was increased in SFMC and SF monocytic cells compared to matched PBMC and PB monocytic cells or SF lymphocytes, correlating with significantly higher protein levels in SF relative to plasma samples. Accordingly, OPN mRNA expression in SF monocytic cells was associated with significant increase of SF protein. Immunohistochemistry revealed the presence of both factors in synovial tissues at the level of the lining and sublining layers, which colocalized with intense CD68 and HIF-1alpha staining, suggesting production by hypoxic synovial monocytic cells. VEGF and OPN expression was abrogated upon SF monocytic cell reoxygenation and maintained by exposure to prolonged hypoxia.

CONCLUSION

Hypoxic synovial monocytic cells are a likely source of VEGF and OPN in JIA. These data point to a role for hypoxia in the perpetuation of synovitis in JIA.

Toll-like receptor 2 is essential for the sensing of oxidants during inflammation

RATIONALE

The mechanisms by which oxidants are sensed by cells and cause inflammation are not well understood.

OBJECTIVES

This study aimed to determine how cells "sense" soluble oxidants and how this is translated into an inflammatory reaction.

METHODS

Monocytes, macrophages, or HEK293 cells (stably transfected with human Toll-like receptor [TLR]2, TLR2/1, TLR2/6, or TLR4/MD2-CD14) were used. CXC ligand-8 (CXCL8) levels were measured using ELISA. Phosphorylated IL-1 receptor-associated kinase 1 levels were measured using Western blot. TLR2(-/-) and TLR4(-/-) mice were challenged with oxidants, and inflammation was measured by monitoring cell infiltration and KC levels.

MEASUREMENTS AND MAIN RESULTS

Oxidants evoked the release of CXCL8 from monocytes/macrophages; this was abrogated by pretreatment with N-acetylcysteine or binding antibodies to TLR2 and was associated with the rapid phosphorylation of IL-1 receptor-associated kinase 1. Oxidants added to HEK293 cells transfected with TLR2, TLR1/2, or TLR2/6 but not TLR4/MD2-CD14 or control HEK nulls resulted in the release of CXCL8. Oxidant challenge delivered intraperitoneally (2-24 hours) or by inhalation to the lungs (3 days) resulted in a robust inflammation in wild-type mice. TLR2(-/-) mice did not respond to oxidant challenge in either model. TLR4(-/-) mice responded as wild-type mice to oxidants at 2 hours but as TLR2(-/-) mice at later time points.

CONCLUSIONS

Oxidant-TLR2 interactions provide a signal that initiates the inflammatory response.

Biochemical markers (NSE, S-100, IL-8) as predictors of neurological outcome in patients after cardiac arrest and return of spontaneous circulation

Predicting the neurological outcome after resuscitation and a return of spontaneous circulation of resuscitated patients still remains a difficult issue. Over the past decade numerous studies have been elaborated to provide the physician with tools to assess as early as possible the neurological outcome of patients with cardiac arrest and return of spontaneous circulation and to decide about further therapeutic management. We summarise the most important ones, giving special focus to three biochemical markers (neuron specific enolase, a protein soluble in 100% ammonium sulfate and interleukin-8), which, when combined with standard neuro-functional and imaging techniques, can serve as potent predictors of neurological outcome in these patients. Despite current limitations about the prognostic significance of these markers - their inferior sensitivity, the different cut-off levels used by several investigators and their variable unequal rise over time - they can give useful information about short and long-term neurological outcome. A comprehensive set of clinical, electrophysiological, biochemical and imaging measures, obtained in a uniform manner in a cohort of patients without limitations in care, could provide a more objective set of comprehensive prognostic indicators.

Dual role of macrophages in tumor growth and angiogenesis

During the neoplastic progression, macrophages as well as dendritic and NK cells are attracted into the tumor site and initiate the immune response against transformed cells. They activate and present tumor antigens to T cells, which are then activated to kill tumor cells. However, tumor cells are often capable of escaping the immune machinery. As the immune surveillance is not sufficient anymore, tumor-associated macrophages contribute to tumor progression. It is notable that tumor-associated macrophages promote the proliferation of tumor cells directly by secreting growth factors. They also participate in tumor progression by acting on endothelial cells and thus promoting the neovascularization of the tumor. Tumor-associated macrophages are indeed key protagonists during angiogenesis and promote each step of the angiogenesis cascade.

Cytokine response in children undergoing surgery for congenital heart disease

Pediatric cardiac surgery with cardiopulmonary bypass (CPB) induces a complex inflammatory response that may cause multiorgan dysfunction. The objective of this study was to measure postoperative cytokine production and correlate the magnitude of this response with intraoperative variables and postoperative outcomes. Serum samples from 20 children (median age, 15 months) undergoing cardiac surgery with CPB were obtained preoperatively and on postoperative days (POD) 1-3. Serum levels of interleukin (IL)-6, IL-8, and IL-10 increased significantly on POD 1 (p < 0.01) vs pre-op values to 271 +/- 68, 44 +/- 9, 7.5 +/- 0.8 pg/ml, respectively, whereas serum IL-1beta, IL-12, and tumor neurosis factor -alpha were not significantly changed. The serum IL-6 and IL-8 levels correlated positively (p < 0.01) with the degree of postoperative medical intervention as measured by the Therapeutic Interventional Scoring System and indicated a greater need for inotropic support (p = 0.057). A negative correlation (p < 0.01) between IL-6, IL-8, and mixed venous oxygen saturation suggested compromised cardiopulmonary function. Patients with single ventricle anatomy had the highest levels of IL-6 and IL-8 (629 +/- 131 and 70 +/- 17 pg/ml, respectively), with a mean CPB time of 106 +/- 23 minutes. Thus, the proinflammatory response after surgery with CPB was associated with postoperative morbidity with increased need for medical intervention.

The role for N-acetylcysteine in the management of COPD

Oxidative stress has been implicated in the pathogenesis and progression of COPD. Both reactive oxidant species from inhaled cigarette smoke and those endogenously formed by inflammatory cells constitute an increased intrapulmonary oxidant burden. Structural changes to essential components of the lung are caused by oxidative stress, contributing to irreversible damage of both parenchyma and airway walls. The antioxidant N-acetylcysteine (NAC), a glutathione precursor, has been applied in these patients to reduce symptoms, exacerbations, and the accelerated lung function decline. This article reviews the available experimental and clinical data on the antioxidative effects of NAC in COPD, with emphasis on the role of exhaled biomarkers.

CXC-chemokine stimulation of neutrophils correlates with plasma levels of myeloperoxidase and lactoferrin and contributes to clinical outcome after pediatric cardiac surgery

Several CXC-chemokines, of which interleukin (IL)-8 is the prototype, are potent neutrophil chemotactic and activating cytokines, inducing the secretion of granule proteins and the generation of reactive oxygen intermediates that may cause tissue damage and amplify inflammatory responses. Here, we investigated whether chemokines play a key role in the inflammatory process following cardiac surgery with cardiopulmonary bypass (CPB) in children. We performed an observational prospective clinical study of 40 pediatric patients before, during, and after open heart surgery with CPB. Plasma levels of chemokines, myeloperoxidase (MPO), and lactoferrin were measured by immunoassays. Cell surface receptors were detected by flow cytometry. Plasma levels of IL-8 were increased after CPB, correlating strongly with a reduction of expression of the CXC-chemokine receptors (CXCR) 1 and 2 on neutrophils indicating in vivo activation of neutrophils by IL-8. Other CXC-chemokines with Glu-Leu-Arg motif showed no correlation with CXCR1 or CXCR2 expression. Two components of neutrophilic granules, MPO and lactoferrin, were strongly elevated postoperatively, and the levels of both were correlated with IL-8. Levels of monocyte chemoattractant protein (MCP)-1 were increased postoperatively, correlating with a reduction of CCR2 expression and an increase of CD11b expression on monocytes, suggesting monocyte activation by MCP-1. The early postoperative course was complicated in patients with an increase of these inflammatory parameters. Impaired cardiovascular function correlated with increased levels of IL-8 and activation of neutrophils and was most prominent in patients with a long time on CPB and in those with cyanotic heart lesions. In conclusion, MCP-1 is involved in the regulation of chemotaxis and function of monocytes during and early after the end of CPB. Activation of neutrophils and down-regulation of CXCR1 and CXCR2 were predominantly caused by IL-8. This activation implies release of components of neutrophilic granules and correlates with the need for inotropic support.

Systemic upregulation of leukocyte integrins in response to lower body ischemia-reperfusion during abdominal aortic aneurysm repair

Ischemia and reperfusion in myocardial infarction and stroke are associated with upregulation of leukocyte adhesion molecules, which contributes to tissue injury by facilitating leukocyte adhesion and infiltration in the affected tissues. Surgical repair of the abdominal aortic aneurysm involves clamping and declamping of the aorta, which necessarily results in ischemia and reperfusion of the lower half of the body. Given the large volume of the affected tissues and unimpeded venous return during reperfusion, we hypothesized that the procedure may result in upregulation of leukocyte integrins in the systemic circulation. To test this hypothesis, we studied neutrophil and monocyte surface densities of CD11b and CD18 in patients undergoing elective infrarenal abdominal aortic aneurysm repair. Serial blood samples were collected from the radial artery and femoral vein during the operation and leukocyte CD11b and CD18 surface densities were quantified by flow cytometry. Following reperfusion, CD11b expression in neutrophils and monocytes increased significantly in femoral venous and arterial blood. The mean time to peak expression of CD11 b in neutrophils and monocytes during reperfusion was 34.4 and 31.4 minutes in venous and 38.5 and 36.4 minutes in arterial blood, respectively. Similar rises in CD18 expression on neutrophils and monocytes were observed in venous and arterial blood. The mean time to peak expression of CD18 in neutrophils and monocytes during reperfusion was 34.0 and 40.0 minutes in venous and 47.5 and 50.0 minutes in arterial blood, respectively.

Effect of stress doses of hydrocortisone on S-100B vs. interleukin-8 and polymorphonuclear elastase levels in human septic shock

Stress doses of hydrocortisone are known to have immunomodulatory effects in patients with hyperdynamic septic shock. The prognosis correlates with the presence and severity of septic encephalopathy. However, neurological evaluation is influenced by the use of analgesia sedation during artificial ventilation. The objective of this study was to demonstrate the effect of stress doses of hydrocortisone during the initial phase of human septic shock on the serum values of the neurospecific protein S-100B in comparison to the inflammation markers interleukin (IL)-8 in serum and polymorphonuclear (PMN) elastase in plasma. A total of 24 consecutive patients, who met the American College of Chest Physicians/Society of Critical Care Medicine criteria for septic shock, were enrolled in this prospective, randomized, double-blind, single-center trial. The severity of illness at recruitment was graded using the Acute Physiology and Chronic Health Evaluation II and the Simplified Acute Physiology Score II scoring systems. Multi-organ dysfunction syndrome was described by the Sepsis-related Organ Failure Assessment (SOFA) score. All patients were prospectively randomized to receive either stress doses of hydrocortisone or placebo. Hydrocortisone was started in 12 patients with a loading dose of 100mg and followed by a continuous infusion of 0.18mg/kg/h for 6days. Median S-100B serum levels of the hydrocortisone group decreased from 0.32ng/mL at study entry to 0.07ng/mL 6days later without significant differences compared to the placebo group. Initial IL-8 serum levels were significantly higher in the hydrocortisone group up to 12h after study entry, and significantly decreased from 715 to 17pg/mL at the end of the observation period. Median PMN elastase plasma levels were not affected by hydrocortisone infusion. Patients with initial S-100B serum levels >0.50ng/mL revealed significantly higher SOFA scores up to 30h, IL-8 serum levels up to 12h, and PMN elastase plasma levels up to 36h after study entry than those patients with ≤0.50ng/mL. These effects were independent of the amount of fluid correction for hemodilution. Starting S-100B, IL-8 and PMN elastase values of the hydrocortisone group were within the ranges already known in patients with out-of-hospital cardiac arrest or severe traumatic brain injury. Stress doses of hydrocortisone resulted in a significant reduction in IL-8 serum, but not in S-100B serum and PMN elastase plasma concentrations in patients with hyperdynamic septic shock. For the first time, a similar extent of S-100B increase in serum of septic patients at the time of diagnosis was shown as reported for cardiac arrest or severe traumatic brain injury.

Angiopoietin-related/angiopoietin-like proteins regulate angiogenesis

A general understanding of the molecular mechanisms underlying angiogenesis is emerging from the analysis of targeted mutations in vasculature-related genes. These analyses reveal that angiopoietin signaling through the TIE2 receptor is involved in regulating angiogenesis. Recently, we and several other groups have independently identified several molecules containing a coiled-coil domain and a fibrinogen-like domain, both of which are structurally conserved in angiopoietins. Because these molecules do not bind to the angiopoietin-specific receptor,TIE2, they have been named angiopoietin-related proteins (ARPs) or angiopoietin-like proteins (Angptls). ARPs/Angptls, which are all currently orphan ligands, also have potent activity for regulating angiogenesis as proangiogenic or antiangiogenic factors, suggesting that their receptors may be expressed on endothelial cells. In addition, ARPs/Angptls show pleiotropic effects not only on vascular cells but also on cells of other lineages, such as skin and chondrocyte cells. More recent studies have proposed that ARPs/Angptls are involved in various pathologies, such as tumor angiogenesis and metabolic diseases. To summarize the current findings relating to these proteins, we focus in this review on the functions of ARPs/Angptls as new angiogenic modulating factors in the vascular system and discuss the pleiotropic functions of ARPs/Angptls in nonvascular cell lineages.

Intracellular glutathione in stretch-induced cytokine release from alveolar type-2 like cells

OBJECTIVE

Ventilator-induced lung injury (VILI) is characterized by release of inflammatory cytokines, but the mechanisms are not well understood. We hypothesized that stretch-induced cytokine production is dependent on oxidant release and is regulated by intracellular glutathione (GSH) inhibition of nuclear factor kappa B (NF-kappa B) and activator protein-1 (AP-1) binding.

METHODOLOGY

Type 2-like alveolar epithelial cells (A549) were exposed to cyclic stretch at 15% strain for 4 h at 20 cycles/min with or without N-acetylcysteine (NAC) or glutathione monoethylester (GSH-e) to increase intracellular GSH, or buthionine sulfoximine (BSO), to deplete intracellular GSH.

RESULTS

Cyclic stretch initially caused a decline in intracellular GSH and a rise in the levels of isoprostane, a marker of oxidant injury. This was followed by a significant increase in intracellular GSH and a decrease in isoprostane. Stretch-induced IL-8 and IL-6 production were significantly inhibited when intracellular GSH was further increased by NAC or GSH-e (P < 0.0001). Stretch-induced IL-8 and IL-6 production were augmented when intracellular GSH was depleted by BSO (P < 0.0001). NAC blocked stretch-induced NF-kappa B and AP-1 binding and inhibited IL-8 mRNA expression.

CONCLUSIONS

We conclude that oxidant release may play a role in lung cell stretch-induced cytokine release, and antioxidants, which increase intracellular GSH, may protect lung cells against stretch-induced injury.

CXCR2 is critical to hyperoxia-induced lung injury

Hyperoxia-induced lung injury is characterized by infiltration of activated neutrophils in conjunction with endothelial and epithelial cell injury, followed by fibrogenesis. Specific mechanisms recruiting neutrophils to the lung during hyperoxia-induced lung injury have not been fully elucidated. Because CXCL1 and CXCL2/3, acting through CXCR2, are potent neutrophil chemoattractants, we investigated their role in mediating hyperoxia-induced lung injury. Under variable concentrations of oxygen, murine survival during hyperoxia-induced lung injury was dose dependent. Eighty percent oxygen was associated with 50% mortality at 6 days, while greater oxygen concentrations were more lethal. Using 80% oxygen, we found that lungs harvested at day 6 demonstrated markedly increased neutrophil sequestration and lung injury. Expression of CXCR2 ligands paralleled neutrophil recruitment to the lung and CXCR2 mRNA expression. Inhibition of CXC chemokine ligands/CXCR2 interaction using CXCR2(-/-) mice exposed to hyperoxia significantly reduced neutrophil sequestration and lung injury, and led to a significant survival advantage as compared with CXCR2(+/+) mice. These findings demonstrate that CXC chemokine ligand/CXCR2 biological axis is critical during the pathogenesis of hyperoxia-induced lung injury.

EFFECT OF HYPOXIA ON MACROPHAGE INFECTION BY LEISHMANIA AMAZONENSIS

In the present study, we compared the effect of 5% oxygen tension (hypoxia) with a normal tension of 21% oxygen (normoxia) on macrophage infection by the protozoan parasite Leishmania amazonensis. Macrophages from different sources (human cell line U937, murine cell line J774, and murine peritoneal macrophages) exposed to hypoxia showed a reduction of the percentage of infected cells and the number of intracellular parasites per cell. Observations on the kinetics of infection indicated that hypoxia did not depress L. amazonensis phagocytosis but induced macrophages to reduce intracellular parasitism. Furthermore, hypoxia did not act synergistically with gamma-interferon and bacterial lipopolysaccharides in macrophages to induce killing of parasites. Experiments also indicated no correlation between nitric oxide production and control of infection in macrophages under hypoxic condition. Thus, we have provided the first evidence that hypoxia, which occurs in various pathological conditions, can alter macrophage susceptibility to a parasitic infection.

Genetic amplification of the transcriptional response to hypoxia as a novel means of identifying regulators of angiogenesis

The cellular response to hypoxia involves the promotion of angiogenesis, leading to increased blood flow and oxygenation. The macrophage has been identified as an orchestrator of this response in several pathologies, through the release of angiogenic factors in response to hypoxia. We have produced the first comprehensive transcriptome analysis of hypoxic primary human macrophages with respect to the regulation of angiogenesis. There is a marked induction of genes encoding factors known to stimulate angiogenesis, rather than factors that inhibit this process. We show that overexpression of the transcription factor EPAS1 using a recombinant adenoviral vector amplifies the induction of genes encoding angiogenic proteins in response to hypoxia. This defines a new strategy for enhancing transcriptome and proteome analyses by overexpressing disease-implicated genes using viral gene transfer methodologies.

Differential roles for NF-kappa B in endotoxin and oxygen induction of interleukin-8 in the macrophage

The alveolar macrophage is an important source of interleukin (IL)-8 during pulmonary injury. The IL-8 gene promoter sequence contains nuclear factor (NF)-kappa B, NF-IL6, and activator protein (AP)-1 binding sequences. These sites may have differing regulatory roles in hyperoxia-exposed macrophages than in those stimulated by bacterial lipopolysaccharide (LPS). U-937 and THP-1 macrophage-like cells were exposed to air-5% CO2 or 95% O2-5% CO2, with or without 1.0 microg/ml of LPS, and transfected with an IL-8 promoter-reporter containing NF-kappa B, NF-IL6, or AP-1 mutations. Hyperoxia and LPS caused additive increases in IL-8 production by U-937 cells, whereas THP-1 cells responded only to LPS. An NF-kappa B mutation ablated baseline and O2- and LPS-stimulated reporter activity in both cell lines, whereas NF-IL6 mutations had little effect. An AP-1 mutation had an intermediate effect. LPS, but not hyperoxia, stimulated nuclear translocation of NF-kappa B in both cell lines. Pharmacological blockade of NF-kappa B nuclear translocation ablated LPS-, but not hyperoxia-, stimulated IL-8 production. Although an intact promoter NF-kappa B site is crucial to macrophage IL-8 production, only LPS-stimulated production appears to require additional nuclear translocation of NF-kappa B.

Effects of hepatovenous back flow on ischemic- reperfusion injuries in liver resections with the pringle maneuver

BACKGROUND

Experimental findings have demonstrated a beneficial role of retrograde blood flow from hepatic veins that takes place during the Pringle maneuver in liver resections. The cytoprotective effect of hepatovenous back-perfusion has not been evaluated in humans. A randomized prospective study was designed to compare the response of liver cells to ischemic-reperfusion injury during the application of two different ischemic procedures: inflow versus inflow plus outflow vascular occlusion of the liver.

STUDY DESIGN

Forty patients were randomly allocated to undergo liver resection using the continuous Pringle maneuver (n = 20) or inflow plus outflow vascular occlusion of the liver by selective hepatic vascular exclusion (n = 20). Liver function was assessed on postoperative days 1 to 6. Response of liver cells to I/R injury was evaluated by measuring interleukins IL-6 and IL-8 at 3, 12, 24, and 48 hours after reperfusion. Oxidative stress was assessed by measuring malondialdehyde levels.

RESULTS

Both groups were comparable regarding ischemic time, operative time, and extent of liver resection. Patients in whom retrograde blood flow to the liver took place during the Pringle maneuver showed better liver function postoperatively and less severe hepatic I/R injuries compared with those undergoing liver resection using both inflow and outflow vascular occlusion. Oxidative stress was significantly lower in the Pringle maneuver group compared with the inflow plus outflow vascular occlusion group (mean [+/- SD] malondialdehyde 8 +/- 2.1 micromol/L in the Pringle group versus 14.7 +/- 1.8 micromol/L in the selective hepatic vascular exclusion group 30 min after reperfusion, p < 0.01).

CONCLUSIONS

Back perfusion via hepatic veins contributes to attenuation of I/R damage during the Pringle maneuver and should be preferred if possible during liver resection.

Chemokines and the inflammatory response following cardiopulmonary bypass--a new target for therapeutic intervention?--A review

This 10-year Medline search of English-language articles describing experimental and clinical studies on chemokines, cardiopulmonary bypass (CPB) and systemic or multiorgan failure revealed that chemokines are significantly involved in the pathogenesis of post-CPB syndrome. The post-CPB inflammatory response depends upon recruitment and activation of inflammatory cells. Leucocyte recruitment is a well-orchestrated process that involves several protein families, including pro-inflammatory cytokines, adhesion molecules and chemokines. Current anti-inflammatory therapies mostly act on the cells that have already been recruited. A more efficient therapy might be the prevention of excessive recruitment of particular leucocyte populations by antagonizing chemokine receptors which might act upstream of the current anti-inflammatory agents. The chemokines, which are a cytokine subfamily of chemotactic cytokines, participate in recognizing, recruiting, removing and repairing inflammation. As chemokines target specific leucocyte subsets, antagonism of a single chemokine ligand or receptor would be expected to have a circumscribed effect, thereby endowing the antagonist with a limited side-effect profile. Chemokines should be considered as possible targets for therapeutic intervention.

Upregulation of Interleukin-8 by Hypoxia in Human Ovaries

PROBLEM

To evaluate the effect of hypoxia on interleukin (IL)-8 expression in human ovarian follicles.

METHOD OF STUDY

Follicular fluid (FF) from each follicle was separately collected from women undergoing in vitro fertilization and embryo transfer. Concentrations of oxygen, progesterone, estradiol, IL-1alpha/beta, IL-8, and tumor necrosis factor (TNF)-alpha in FF were measured. Isolated granulosa-lutein cells (GLC) from obtained FF were cultured under normoxic or hypoxic conditions, and concentrations of IL-8 in culture media were measured.

RESULTS

Simple regression analysis demonstrated a significant negative correlation between the concentrations of IL-8 and oxygen in FF (r = 0.50, P < 0.0001). However, none of the concentrations of progesterone, estradiol, IL-1beta, and TNF-alpha in FF showed a significant correlation with IL-8 concentrations. Hypoxia stimulated the secretion of IL-8 by cultured GLC over twofolds compared with a normoxic control (P < 0.05).

CONCLUSIONS

These findings suggest that IL-8, like other angiogenic factors, is upregulated under hypoxic condition, which argues that hypoxia in the ovarian follicles comes into play in ovarian functions by inducing a range of proangiogenic and chemoattractive substances.