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

Effects of Oxygen Therapy on Patients with a Chronic Wound: A Systematic Review and Meta-analysis

OBJECTIVE

To synthesize the effects of oxygen-based therapy on patients with a chronic wound.

DATA SOURCES

The authors searched PubMed, EMBASE, and Cochrane Central Register of Controlled Trials for relevant randomized controlled trials from database inception. Investigators measured risk of bias using the Cochrane Collaboration's Risk of Bias tool.

STUDY SELECTION

The included randomized controlled trials focused on the effects (short- or long-term wound healing, amputation rate, percentage of reduction in ulcer size, and poststudy transcutaneous oxygen measurement [TcPO2]) of oxygen-based therapy (including hyperbaric oxygen therapy, topical oxygen therapy, and continuous diffusion of oxygen) on patients with a chronic wound.

DATA EXTRACTION

Researchers extracted information regarding participant characteristics and primary and secondary outcomes from the included studies.

DATA SYNTHESIS

Pooled effects of 31 included studies showed that patients treated with oxygen had better short-term wound healing (risk ratio [RR], 1.544; 95% CI, 1.199 to 1.987), a higher percentage reduction in the ulcer area (standardized mean difference [SMD], 0.999; 95% CI, 0.439 to 1. 599), lower amputation rates (RR, 0.529; 95% CI, 0.325 to 0.862), shorter wound healing time (SMD, -0.705; 95% CI, -0.908 to -0.501), and higher poststudy TcPO2 (SMD, 2.128; 95% CI, 0.978 to 3.278) than those in the control group. For long-term wound healing, there was no statistically significant difference (RR, 1.227; 95% CI, 0.976 to 1.542).

CONCLUSIONS

Oxygen-based therapy improves short-term parameters of wound healing in patients with chronic wounds.

MicroRNAs in Juvenile Idiopathic Arthritis: State of the Art and Future Perspectives

Juvenile Idiopathic Arthritis (JIA) represents the most common chronic pediatric arthritis in Western countries and a leading cause of disability in children. Despite recent clinical achievements, patient management is still hindered by a lack of diagnostic/prognostic biomarkers and targeted treatment protocols. MicroRNAs (miRNAs) are short non-coding RNAs playing a key role in gene regulation, and their involvement in many pathologies has been widely reported in the literature. In recent decades, miRNA's contribution to the regulation of the immune system and the pathogenesis of autoimmune diseases has been demonstrated. Furthermore, miRNAs isolated from patients' biological samples are currently under investigation for their potential as novel biomarkers. This review aims to provide an overview of the state of the art on miRNA investigation in JIA. The literature addressing the expression of miRNAs in different types of biological samples isolated from JIA patients was reviewed, focusing in particular on their potential application as diagnostic/prognostic biomarkers. The role of miRNAs in the regulation of immune responses in affected joints will also be discussed along with their potential utility as markers of patients' responses to therapeutic approaches. This information will be of value to investigators in the field of pediatric rheumatology, encouraging further research to increase our knowledge of miRNAs' potential for future clinical applications in JIA.

Proteomic profiling of extracellular vesicles in synovial fluid and plasma from Oligoarticular Juvenile Idiopathic Arthritis patients reveals novel immunopathogenic biomarkers

Introduction

New early low-invasive biomarkers are demanded for the management of Oligoarticular Juvenile Idiopathic Arthritis (OJIA), the most common chronic pediatric rheumatic disease in Western countries and a leading cause of disability. A deeper understanding of the molecular basis of OJIA pathophysiology is essential for identifying new biomarkers for earlier disease diagnosis and patient stratification and to guide targeted therapeutic intervention. Proteomic profiling of extracellular vesicles (EVs) released in biological fluids has recently emerged as a minimally invasive approach to elucidate adult arthritis pathogenic mechanisms and identify new biomarkers. However, EV-prot expression and potential as biomarkers in OJIA have not been explored. This study represents the first detailed longitudinal characterization of the EV-proteome in OJIA patients.

Methods

Fourty-five OJIA patients were recruited at disease onset and followed up for 24 months, and protein expression profiling was carried out by liquid chromatography-tandem mass spectrometry in EVs isolated from plasma (PL) and synovial fluid (SF) samples.

Results

We first compared the EV-proteome of SF vs paired PL and identified a panel of EV-prots whose expression was significantly deregulated in SF. Interaction network and GO enrichment analyses performed on deregulated EV-prots through STRING database and ShinyGO webserver revealed enrichment in processes related to cartilage/bone metabolism and inflammation, suggesting their role in OJIA pathogenesis and potential value as early molecular indicators of OJIA development. Comparative analysis of the EV-proteome in PL and SF from OJIA patients vs PL from age/gender-matched control children was then carried out. We detected altered expression of a panel of EV-prots able to differentiate new-onset OJIA patients from control children, potentially representing a disease-associated signature measurable at both the systemic and local levels with diagnostic potential. Deregulated EV-prots were significantly associated with biological processes related to innate immunity, antigen processing and presentation, and cytoskeleton organization. Finally, we ran WGCNA on the SF- and PL-derived EV-prot datasets and identified a few EV-prot modules associated with different clinical parameters stratifying OJIA patients in distinct subgroups.

Discussion

These data provide novel mechanistic insights into OJIA pathophysiology and an important contribution in the search of new candidate molecular biomarkers for the disease.

Simulated hypoxia modulates P2X7 receptor function in mice peritoneal macrophages

The inflammatory focus is similar to the tumor microenvironment, which contains a complex milieu with immune cells and macrophages. The accumulation of cells promotes local pH and O₂ tension decline (hypoxia). Local O₂ tension decline activates hypoxia-inducible factor α and β (HIF-1α and HIF-1β adenosine triphosphate (ATP) release. ATP activates the P2X7 receptor and modulates ischemic/hypoxic conditions. Similarly, α1α may regulate P2X7 receptor expression in the hypoxic microenvironment. Therefore, we investigated P2X7 receptor function under simulated hypoxic conditions by pretreating peritoneal macrophages with mitochondrial electron transport chain complex inhibitors (simulated hypoxia). Treatment with mitochondrial electron transport chain complex inhibitors until three hours of exposure did not cause LDH release. Additionally, mitochondrial electron transport chain complex inhibitors increased ATP-induced P2X7 receptor function without being able to directly activate this receptor. Other P2 receptor subtypes do not appear to participate in this mechanism. Simulated hypoxia augmented HIF-1α levels and suppressed HIF-1α and P2X7 receptor antagonists. Similarly, simulated hypoxia increased ATP-induced dye uptake and inhibited HIF-1α antagonists. Another factor activated in simulated hypoxic conditions was the intracellular P2X7 receptor regulator PIP2. Treatment with HIF-1α agonists increased PIP2 levels and reversed the effects of HIF-1α and P2X7 receptor antagonists. Additionally, the improved ATP-induced dye uptake caused by the simulated hypoxia stimulus was inhibited by P2X7 receptor and PIP2 antagonists. Therefore, simulated hypoxia may augment P2X7 receptor activity for a pathway dependent on HIF-1α and PIP2 activation.

Signals and Mechanisms Regulating Monocyte and Macrophage Activation in the Pathogenesis of Juvenile Idiopathic Arthritis

Monocytes (Mos) and macrophages (Mφs) are key players in the innate immune system and are critical in coordinating the initiation, expansion, and regression of many autoimmune diseases. In addition, they display immunoregulatory effects that impact inflammation and are essential in tissue repair and regeneration. Juvenile idiopathic arthritis (JIA) is an umbrella term describing inflammatory joint diseases in children. Accumulated evidence suggests a link between Mo and Mφ activation and JIA pathogenesis. Accordingly, topics regarding the signals and mechanisms regulating Mo and Mφ activation leading to pathologies in patients with JIA are of great interest. In this review, we critically summarize recent advances in the understanding of how Mo and Mφ activation is involved in JIA pathogenesis and focus on the signaling pathways and mechanisms participating in the related cell activation processes.

Upregulated expression of hypoxia reactive genes in peripheral blood mononuclear cells from chronic liver disease patients

Liver fibrosis induces intrahepatic microcirculation disorder and hypoxic stress. Hypoxic stress has the potential for an increase in the possibility of more liver fibrosis and carcinogenesis. Liver biopsy is a standard method that evaluates of intrahepatic hypoxia, however, is invasive and has a risk of bleeding as a complication. Here, we investigated the hypoxia reactive gene expressions in peripheral blood mononuclear cells (PBMC) from chronic liver disease patients to evaluate intrahepatic hypoxia in a non-invasive manner. The subjects enrolled for this study were composed of 20 healthy volunteers (HV) and 48 patients with chronic liver disease (CLD). CLD patients contained 24 patients with chronic hepatitis（CH）and 24 patients with liver cirrhosis (LC). PBMC were isolated from heparinized peripheral blood samples. We measured the transcriptional expression of hypoxia reactive genes and inflammatory cytokines by quantitative RT-PCR. mRNA expression of adrenomedullin (AM), vascular endothelial growth factor A (VEGFA) superoxide dismutase (SOD), glutathione peroxidase (GPx) (p < 0.05), Interleukin-6 (IL-6), transforming growth factor-beta (TGF-β) and heme oxygenase-1 (HO-1) in CLD group were significantly higher than HV. AM mRNA expression is correlated with serum lactate dehydrogenase (LDH), serum albumin (Alb), IL6, and SOD mRNA expression. The hypoxia reactive gene expression in PBMCs from CLD patients was more upregulated than HV. Especially, angiogenic genes were notably upregulated and correlated with liver fibrosis. Here, we suggest that mRNA expression of AM in PBMCs could be the biomarker of intrahepatic hypoxia.

•

The hypoxia reactive genes in PBMC were elevated in patients with chronic liver disease.

^•Angiogenic genes were upregulated and correlated with liver fibrosis in patients with chronic liver disease.

^•Adrenomedullin mRNA expression in PBMC was correlated with liver function.

^•mRNA expression of adrenomedullin in PBMC could be the biomarker of intrahepatic hypoxia.

Effect of oxygen-producing suture material on hypoxic colonic anastomoses in an experimental model

Background

Anastomotic leak remains a significant cause of morbidity and mortality after colorectal surgery. Among multiple risk factors considered, hypoxia–ischaemia is considered to be a primary cause of intestinal anastomotic leakage. The aim of this experimental study was to assess safety, usability for surgical tasks, and efficacy of a newly developed oxygen‐producing suture material in the healing of colonic anastomoses under critical conditions.

Methods

An oxygen‐producing suture material was produced that is capable of releasing oxygen directly into the surrounding tissue. Off‐the‐shelf sutures loaded with calcium peroxide nano‐crystals and covered with poly(d,l‐lactide‐co‐glycolide) were assessed in vitro and in a rat model of hypoxic colonic anastomosis.

Results

In vitro assessment showed that these sutures can increase oxygen levels in a hypoxic environment. Potential oxygen byproducts did not seem to have a negative impact on the viability of intestinal cells. The use of oxygen‐producing sutures in vivo resulted in increased tissue oxygen saturation, measured by visible light spectroscopy, and increased mechanical stability of the anastomosis.

Conclusion

Oxygen‐producing suture material increased tissue oxygen saturation and mechanical stability of colonic anastomosis in a rat model.

Roles of Macrophage Subtypes in Bowel Anastomotic Healing and Anastomotic Leakage

Macrophages play an important role in host defense, in addition to the powerful ability to phagocytose pathogens or foreign matters. They fulfill a variety of roles in immune regulation, wound healing, and tissue homeostasis preservation. Macrophages are characterized by high heterogeneity, which can polarize into at least two major extremes, M1-type macrophages (classical activation) which are normally derived from monocytes and M2-type macrophages (alternative activation) which are mostly those tissue-resident macrophages. Based on the wound healing process in skin, the previous studies have documented how these different subtypes of macrophages participate in tissue repair and remodeling, while the mechanism of macrophages in bowel anastomotic healing has not yet been established. This review summarizes the currently available evidence regarding the different roles of polarized macrophages in the physiological course of anastomotic healing and their pathological roles in anastomotic leakage, the most dangerous complication after gastrointestinal surgery.

Regulation of Human Macrophage M1-M2 Polarization Balance by Hypoxia and the Triggering Receptor Expressed on Myeloid Cells-1

Macrophages (Mf) are a heterogeneous population of tissue-resident professional phagocytes and a major component of the leukocyte infiltrate at sites of inflammation, infection, and tumor growth. They can undergo diverse forms of activation in response to environmental factors, polarizing into specialized functional subsets. A common hallmark of the pathologic environment is represented by hypoxia. The impact of hypoxia on human Mf polarization has not been fully established. The objective of this study was to elucidate the effects of a hypoxic environment reflecting that occurring in vivo in diseased tissues on the ability of human Mf to polarize into classically activated (proinflammatory M1) and alternatively activated (anti-inflammatory M2) subsets. We present data showing that hypoxia hinders Mf polarization toward the M1 phenotype by decreasing the expression of T cell costimulatory molecules and chemokine homing receptors and the production of proinflammatory, Th1-priming cytokines typical of classical activation, while promoting their acquisition of phenotypic and secretory features of alternative activation. Furthermore, we identify the triggering receptor expressed on myeloid cells (TREM)-1, a member of the Ig-like immunoregulatory receptor family, as a hypoxia-inducible gene in Mf and demonstrate that its engagement by an agonist Ab reverses the M2-polarizing effect of hypoxia imparting a M1-skewed phenotype to Mf. Finally, we provide evidence that Mf infiltrating the inflamed hypoxic joints of children affected by oligoarticular juvenile idiopatic arthritis express high surface levels of TREM-1 associated with predominant M1 polarization and suggest the potential of this molecule in driving M1 proinflammatory reprogramming in the hypoxic synovial environment.

Differential roles of hypoxia and innate immunity in juvenile and adult dermatomyositis

Dermatomyositis (DM) can occur in both adults and juveniles with considerable clinical differences. The links between immune-mediated mechanisms and vasculopathy with respect to development of perifascicular pathology are incompletely understood. We investigated skeletal muscle from newly diagnosed, treatment-naïve juvenile (jDM) and adult dermatomyositis (aDM) patients focusing on hypoxia-related pathomechanisms, vessel pathology, and immune mechanisms especially in the perifascicular region. Therefore, we assessed the skeletal muscle biopsies from 21 aDM, and 15 jDM patients by immunohistochemistry and electron microscopy. Transcriptional analyses of genes involved in hypoxia, as well as in innate and adaptive immunity were performed by quantitative Polymerase chain reaction (qPCR) of whole tissue cross sections including perifascicular muscle fibers.Through these analysis, we found that basic features of DM, like perifascicular atrophy and inflammatory infiltrates, were present at similar levels in jDM and aDM patients. However, jDM was characterized by predominantly hypoxia-driven pathology in perifascicular small fibers and by macrophages expressing markers of hypoxia. A more pronounced regional loss of capillaries, but no relevant activation of type-1 Interferon (IFN)-associated pathways was noted. Conversely, in aDM, IFN-related genes were expressed at significantly elevated levels, and Interferon-stimulated gene (ISG)15 was strongly positive in small perifascicular fibers whereas hypoxia-related mechanisms did not play a significant role.In our study we could provide new molecular data suggesting a conspicuous pathophysiological 'dichotomy' between jDM and aDM: In jDM, perifascicular atrophy is tightly linked to hypoxia-related pathology, and poorly to innate immunity. In aDM, perifascicular atrophy is prominently associated with molecules driving innate immunity, while hypoxia-related mechanisms seem to be less relevant.

Interactions between osteopontin and vascular endothelial growth factor: Implications for cancer

For this comprehensive review, 257 publications with the keywords "osteopontin" or "OPN" and "vascular endothelial growth factor" or "VEGF" in PubMed were screened (time frame from year 1996 to year 2014). 37 articles were excluded because they were not focused on the interactions between these molecules, and papers relevant for transformation-related phenomena were selected. Osteopontin (OPN) and vascular endothelial growth factor (VEGF) are characterized by a convergence in function for regulating cell motility and angiogenesis, the response to hypoxia, and apoptosis. Often, they are co-expressed or one molecule induces the other, however, in some settings OPN-associated pathways and VEGF-associated pathways are distinct. Their relationships affect the pathogenesis in cancer, where they contribute to progression and angiogenesis and serve as markers for poor prognosis. The inhibition of OPN may reduce VEGF levels and suppress tumor progression. In vascular pathologies, these two cytokines mediate remodeling, but may also perpetuate inflammation and narrowing of the arteries. OPN and VEGF are elevated and contribute to vascularization in inflammatory diseases.

Relationship of plasma and synovial fluid vascular endothelial growth factor with radiographic severity in primary knee osteoarthritis

PURPOSE

Recent evidence suggests that angiogenesis and inflammation contribute to the development and progression of osteoarthritis (OA). The purpose of this study was to investigate vascular endothelial growth factor (VEGF) levels in plasma and synovial fluid of patients with knee OA and to determine the relationship of VEGF levels with disease severity in knee OA.

METHODS

A total of 100 subjects were enrolled in this study (80 knee OA patients and 20 healthy controls). Plasma and synovial fluid VEGF levels were analysed using enzyme-linked immunosorbent assay. VEGF expressions in synovial membrane and articular cartilage samples were assessed using immunohistochemistry.

RESULTS

VEGF level in synovial fluid of knee OA patients was tenfold higher than that in paired plasma (P < 0.001). Both plasma and synovial fluid VEGF exhibited a positive correlation with radiographic severity (r = 0.454 and r = 0.727, P < 0.001, respectively). VEGF expression was highly detectable in synovial lining cells and articular chondrocytes of knee OA patients.

CONCLUSIONS

VEGF levels in both plasma and synovial fluid were positively correlated with the severity of knee OA. Therefore, VEGF may be useful for monitoring OA severity and could play a substantial role in the development and progression of knee OA.

HMGB1 levels are increased in patients with juvenile idiopathic arthritis, correlate with early onset of disease, and are independent of disease duration

OBJECTIVE

High mobility group box chromosomal protein 1 (HMGB1) has been implicated as a mediator of inflammation in rheumatoid arthritis (RA), while its role in juvenile idiopathic arthritis (JIA) has not been described. To evaluate the role of HMGB1 in the inflammatory process in JIA and its potential as a therapeutic target, we investigated whether extracellular HMGB1 is detectable in JIA and if so, to correlate the levels with established inflammatory markers and clinical measures.

METHODS

Matching samples of blood and synovial fluid (SF) were collected from 23 patients with JIA. Levels of HMGB1, soluble receptor for advanced glycation endproducts, S100A12, myeloid-related protein 8/14, and other inflammatory mediators were analyzed.

RESULTS

Significantly increased HMGB1 levels were recorded in SF compared to blood samples from patients with JIA. The amount of HMGB1 was highest in patients with early disease onset irrespective of disease duration. In contrast, the proinflammatory S100 protein and interleukin 8 were highest in patients in early phases of disease. Matrix metalloproteinase-3, a marker of cartilage destruction, was higher in patients with late disease onset, indicating similarities with RA in that patient subgroup.

CONCLUSION

Levels of extracellular HMGB1 are increased in the inflamed joints of patients with JIA. This warrants further studies of HMGB1 as a mediator of JIA pathogenesis as well as a biomarker for inflammatory activity and as a target for therapy. The variation in levels of HMGB1 and S100 proteins in relation to disease onset indicates a difference in inflammatory phenotype during disease progression.

Oxygen and wound care: a review of current therapeutic modalities and future direction

While the importance of oxygen to the wound healing process is well accepted, research and technological advances continue in this field and efforts are ongoing to further utilize oxygen as a therapeutic modality. In this paper, the authors briefly review the role of oxygen in wound healing and discuss the distinct mechanism of action as well as the advantages and disadvantages of the three major oxygen-based therapies currently in clinical use (Hyperbaric Oxygen and Topical Oxygen and Continuous Diffusion of Oxygen), as well as review the existing literature regarding these distinct therapeutic modalities.

Hypoxia-mediated regulation of macrophage functions in pathophysiology

Oxygen availability affects cell differentiation, survival and function, with profound consequences on tissue homeostasis, inflammation and immunity. A gradient of oxygen levels is present in most organs of the body as well as in virtually every site of inflammation, damaged or pathological tissue. As a consequence, infiltrating leukocytes, macrophages in particular, are equipped with the capacity to shift their metabolism to anaerobic glycolysis, to generate ATP and induce the expression of factors that increase the supply of oxygen and nutrients. Strikingly, low oxygen conditions (hypoxia) and inflammatory signals share selected transcriptional events, including the activation of members of both the hypoxia-inducible factor and nuclear factor κB families, which may converge to activate specific cell programs. In the pathological response to hypoxia, cancer in particular, macrophages act as orchestrators of disease evolution and their number can be used as a prognostic marker. Here we review mechanisms of macrophage adaptation to hypoxia, their role in disease as well as new perspectives for their therapeutic targeting.

Dendritic cell reprogramming by the hypoxic environment

Myeloid dendritic cells (DCs) are professional antigen-presenting cells central to the orchestration of innate and acquired immunity and the maintenance of self-tolerance. The local microenvironment contributes to the regulation of DC development and functions, and deregulated DC responses may result in amplification of inflammation, loss of tolerance, or establishment of immune escape mechanisms. DC generation from monocytic precursors recruited at sites of inflammation, tissue damage, or neoplasia occurs under condition of low partial oxygen pressure (pO(2), hypoxia). We reviewed the literature addressing the phenotypic and functional changes triggered by hypoxia in monocyte-derived immature (i) and mature (m) DCs. The discussion will revolve around in vitro studies of gene expression profile, which give a comprehensive representation of the complexity of response of these cells to low pO(2). The gene expression pattern of hypoxic DC will be discussed to address the question of the relationship with a specific maturation stage. We will summarize data relative to the regulation of the chemotactic network, which points to a role for hypoxia in promoting a migratory phenotype in iDCs and a highly proinflammatory state in mDCs. Current knowledge of the strict regulatory control exerted by hypoxia on the expression of immune-related cell surface receptors will also be addressed, with a particular focus on a newly identified marker of hypoxic DCs endowed with proinflammatory properties. Furthermore, we discuss the literature on the transcription mechanisms underlying hypoxia-regulated gene expression in DCs, which support a major role for the HIF/HRE pathway. Finally, recent advances shedding light on the in vivo influence of the local hypoxic microenvironment on DCs infiltrating the inflamed joints of juvenile idiopathic arthritis patients are outlined.

Human early fracture hematoma is characterized by inflammation and hypoxia

BACKGROUND

An effective immune system, especially during the inflammatory phase, putatively influences the quality and likelihood of bone healing. If and how this is reflected within the initial fracture hematoma is unclear.

QUESTIONS/PURPOSES

We therefore asked the following questions: (1) Does the local expression in fracture hematoma of genes involved in adaptation to hypoxia, migration, angiogenesis, and osteogenesis vary as compared to the peripheral blood? (2) Do these changes occur time dependently? (3) Is the gene expression during fracture hematoma formation altered by irradiation?

METHODS

Cells from fracture hematoma of 20 patients and hematomas formed in 40 patients after THA (20 without and 20 with preoperative radiation) were isolated and RNA was extracted to analyze the influence of oxygen deprivation during fracture healing on mRNA expression of genes (HIF1A, LDHA, and PGK1) involved in immunoregulation (IL6, IL8, CXCR4), angiogenesis (VEGF, IL8), and osteogenesis (SPP1, RUNX2) by quantitative PCR.

RESULTS

We observed locally increased LDHA gene expression in fracture hematoma cells (6-72 h post fracture) reflecting the adaptation to hypoxia. IL6, IL8, and VEGF upregulation indicated hypoxia-mediated inflammation and angiogenesis; increased CXCR4 expression reflected immigration of immune cells. Osteogenic differentiation was reflected in the increased expression of the SPP1 and RUNX2 genes. The increased expression of the LDHA, VEGF, IL8, SPP1 and RUNX2 genes occurred time dependently. Irradiation suppressed HIF1A, IL6, IL8, CXCR4, and RUNX2 gene expression.

CONCLUSIONS

Our data suggest cells in the fracture hematoma (1) adapt to hypoxia and (2) promote inflammation in fracture healing at the mRNA level, indicating early involvement of the immune system.

CLINICAL RELEVANCE

The initial fracture hematoma is important for the onset of angiogenesis, chemotaxis, and osteogenesis.

Osteopontin in macrophage function

The secreted phosphorylated protein osteopontin (OPN) is expressed in a variety of tissues and bodily fluids, and is associated with pathologies including tissue injury, infection, autoimmune disease and cancer. Macrophages are ubiquitous, heterogeneous cells that mediate aspects of cell and tissue damage in all these pathologies. Here, the role of OPN in macrophage function is reviewed. OPN is expressed in macrophage cells in multiple pathologies, and the regulation of its expression in these cells has been described in vitro. The protein has been implicated in multiple functions of macrophages, including cytokine expression, expression of inducible nitric oxide synthase, phagocytosis and migration. Indeed, the role of OPN in cells of the macrophage lineage might underlie its physiological role in many pathologies. However, there are numerous instances where the published literature is inconsistent, especially in terms of OPN function in vitro. Although the heterogeneity of OPN and its receptors, or of macrophages themselves, might underlie some of these inconsistencies, it is important to understand the role of OPN in macrophage biology in order to exploit its function therapeutically.

Low flow oxygenation of full-excisional skin wounds on diabetic mice improves wound healing by accelerating wound closure and reepithelialization

Oxygen-based therapies have proven effective in treating chronic and difficult-to-heal skin wounds, but the current therapeutic approaches suffer from major limitations and they do not allow for continuous wound treatment. Here we examined whether the continuous treatment of wounds with pure oxygen at low flow rates accelerates wound closure and improves wound healing in a murine model of diabetic skin wounds. Two full-excisional dorsal skin wounds were generated on 15-week-old diabetic db/db mice and treated for 10 weeks continuously with pure oxygen (>99·9%) at low flow rates (3 ml/h). After 6 days, oxygen treatment resulted in a mean reduction of the original wound size by 60·2% as compared with only 45·2% in wounds on control mice that did not receive pure oxygen.(P = 0·022). After 10 days, oxygen-treated wounds were 83·1% closed compared with 71·2% in wounds on control mice. While reepithelialisation was complete after 10 days in over 57% of wounds receiving low flow oxygen treatment, significant epithelial gaps remained in 75% wounds from mice that did not receive oxygen. Continuous low flow oxygenation significantly improves healing of diabetic skin wounds in mice and may therefore be an effective treatment for chronic cutaneous and possibly other slow-healing wounds in diabetic patients.

Hypoxia modulates the gene expression profile of immunoregulatory receptors in human mature dendritic cells: identification of TREM-1 as a novel hypoxic marker in vitro and in vivo

Dendritic cells (DCs) are a heterogeneous group of professional antigen-presenting cells functioning as sentinels of the immune system and playing a key role in the initiation and amplification of innate and adaptive immune responses. DC development and functions are acquired during a complex differentiation and maturation process influenced by several factors present in the local milieu. A common feature at pathologic sites is represented by hypoxia, a condition of low pO(2), which creates a unique microenvironment affecting cell phenotype and behavior. Little is known about the impact of hypoxia on the generation of mature DCs (mDCs). In this study, we identified by gene expression profiling a significant cluster of genes coding for immune-related cell surface receptors strongly up-regulated by hypoxia in monocyte-derived mDCs and characterized one of such receptors, TREM-1, as a new hypoxia-inducible gene in mDCs. TREM-1 associated with DAP12 in hypoxic mDCs, and its engagement elicited DAP12-linked signaling, resulting in ERK-1, Akt, and IκBα phosphorylation and proinflammatory cytokine and chemokine secretion. Finally, we provided the first evidence that TREM-1 is expressed on mDCs infiltrating the inflamed hypoxic joints of children affected by juvenile idiopathic arthritis, representing a new in vivo marker of hypoxic mDCs endowed with proinflammatory properties.

Blood-induced joint disease: the pathophysiology of hemophilic arthropathy

Arthropathy is a frequent and serious complication of repeated joint bleeding in patients with hemophilia, resulting in pain, deformity, and disability. Although the pathogenesis of hemophilic arthropathy has not been fully elucidated, it appears to have similarities with the degenerative joint damage that occurs in osteoarthritis and the inflammatory processes associated with rheumatoid arthritis. This article reviews the potential actions of various blood constituents on joint components that culminate in the development of hemophilic arthropathy.

Salivary antioxidants and metalloproteinases in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common autoimmune inflammatory disease in children; joint inflammation is the hallmark of the disease. Thirty-five children with JIA were studied, of whom 26 had active disease and 14 were receiving anti-TNF therapy (5 with Infliximab, 9 with Etanercept). Sixteen healthy controls also were studied. Saliva samples were obtained for analysis of anti-oxidant status, metalloproteinases (MMPs) and sialochemistry. The total antioxidant status was significantly higher in the saliva of all JIA patients, whether treated (P = 0.014) or not treated (P = 0.038) with anti-TNF agents. The increase in antioxidant status (TAS) in the saliva of the active patients was nearly two times higher than that of non-active patients (P = 0.01). MMP levels were significantly lower in JIA patients than in controls. MMP-9, MMP-3 and MMP-2 were lower in JIA patients without anti-TNF treatment by 36.7% (P = 0.01), 30.0% (P = 0.0001) and 10.7% (P = 0.0001), respectively. A greater reduction in MMP levels was observed in the group of patients treated with anti-TNF drugs: MMP-9, MMP-3 and MMP-2 were lower than in controls by 51.1% (P = 0.0001), 61.5% (P = 0.0001) and 55.4% (P = 0.0001), respectively. Children with JIA exhibited a significantly higher salivary antioxidant activity and significantly lower MMP levels. Anti-TNF treatment was associated with a further decrease in MMP levels in the saliva of JIA patients while an active state of JIA was associated with a further increase in the salivary antioxidant activity. Anti-TNF treatment may modulate the degradation process during the course of arthritis by inhibition of the activity of MMP.