Variability in Cardiac miRNA-122 Level Determines Therapeutic Potential of miRNA-Regulated AAV Vectors.

Systemically delivered adeno-associated viral vector serotype 9 (AAV9) effectively transduces murine heart, but provides transgene expression also in liver and skeletal muscles. Improvement of the selectivity of transgene expression can be achieved through incorporation of target sites (TSs) for miRNA-122 and miRNA-206 into the 3' untranslated region (3' UTR) of the expression cassette. Here, we aimed to generate such miRNA-122- and miRNA-206-regulated AAV9 vector for a therapeutic, heart-specific overexpression of heme oxygenase-1 (HO-1). We successfully validated the vector functionality in murine cell lines corresponding to tissues targeted by AAV9. Next, we evaluated biodistribution of transgene expression following systemic vector delivery to HO-1-deficient mice of mixed C57BL/6J × FVB genetic background. Although AAV genomes were present in the hearts of these animals, HO-1 protein expression was either absent or significantly impaired. We found that miRNA-122, earlier described as liver specific, was present also in the hearts of C57BL/6J × FVB mice. Various levels of miRNA-122 expression were observed in the hearts of other mouse strains, in heart tissues of patients with cardiomyopathy, and in human induced pluripotent stem cell-derived cardiomyocytes in which we also confirmed such posttranscriptional regulation of transgene expression. Our data clearly indicate that therapeutic utilization of miRNA-based regulation strategy needs to consider inter-individual variability.

Dysregulated miR-125a promotes angiogenesis through enhanced glycolysis.

BACKGROUND: Although neoangiogenesis is a hallmark of chronic inflammatory diseases such as inflammatory arthritis and many cancers, therapeutic agents targeting the vasculature remain elusive. Here we identified miR-125a as an important regulator of angiogenesis. METHODS: MiRNA levels were quantified in Psoriatic Arthritis (PsA) synovial-tissue by RT-PCR and compared to macroscopic synovial vascularity. HMVEC were transfected with anti-miR-125a and angiogenic mechanisms quantified using tube formation assays, transwell invasion chambers, wound repair, RT-PCR and western blot. Real-time analysis of EC metabolism was assessed using the XF-24 Extracellular-Flux Analyzer. Synovial expression of metabolic markers was assessed by immunohistochemistry and immunofluorescent staining. MiR-125a CRISPR/Cas9-based knock-out zebrafish were generated and vascular development assessed. Finally, glycolytic blockade using 3PO, which inhibits Phosphofructokinase-fructose-2,6-bisphophatase 3 (PFKFB3), was assessed in miR-125a-/- ECs and zebrafish embryos. FINDINGS: MiR-125a is significantly decreased in PsA synovium and inversely associated with macroscopic vascularity. In-vivo, CRISPR/cas9 miR-125a-/- zebrafish displayed a hyper-branching phenotype. In-vitro, miR-125a inhibition promoted EC tube formation, branching, migration and invasion, effects paralleled by a shift in their metabolic profile towards glycolysis. This metabolic shift was also observed in the PsA synovial vasculature where increased expression of glucose transporter 1 (GLUT1), PFKFB3 and Pyruvate kinase muscle isozyme M2 (PKM2) were demonstrated. Finally, blockade of PFKFB3 significantly inhibited anti-miR-125a-induced angiogenic mechanisms in-vitro, paralleled by normalisation of vascular development of CRISPR/cas9 miR-125a-/- zebrafish embryos. INTEPRETATION: Our results provide evidence that miR-125a deficiency enhances angiogenic processes through metabolic reprogramming of endothelial cells. FUND: Irish Research Council, Arthritis Ireland, EU Seventh Framework Programme (612218/3D-NET).

Enriched Cd141+ DCs in the joint are transcriptionally distinct, activated, and contribute to joint pathogenesis.

CD141+ DC are implicated in antiviral and antitumor immunity. However, mechanistic studies in autoimmune disease are limited. This is the first study to our knowledge examining CD141+ DC in autoimmune disease, specifically inflammatory arthritis (IA). We identified significant enrichment of CD141+ DC in the inflamed synovial joint, which were transcriptionally distinct from IA and healthy control (HC) blood CD141+ DC and significantly more activated, and they exhibited increased responsiveness to TLR3. Synovial CD141+ DC represent a bone fide CD141+ DC population that is distinct from CD1c+ DC. Synovial CD141+ DC induced higher levels of CD4+ and CD8+ T cell activation compared with their peripheral blood counterparts, as made evident by expression of IFN-γ, TNF-α, and granulocyte-macrophage CSF (GMCSF). Autologous synovial CD141+ DC cocultures also induce higher levels of these cytokines, further highlighting their contribution to synovial inflammation. Synovial CD141+ DC-T cell interactions had the ability to further activate synovial fibroblasts, inducing adhesive and invasive pathogenic mechanisms. Furthermore, we identify a mechanism in which synovial CD141+ DC are activated, via ligation of the hypoxia-inducible immune-amplification receptor TREM-1, which increased synovial CD141+ DC activation, migratory capacity, and proinflammatory cytokines. Thus, synovial CD141+ DC display unique mechanistic and transcriptomic signatures, which are distinguishable from blood CD141+ DC and can contribute to synovial joint inflammation.

The Utility and Limitations of CRP, ESR and DAS28-CRP in Appraising Disease Activity in Rheumatoid Arthritis.

Introduction: Identifying and quantifying inflammatory disease activity in rheumatoid arthritis remains a challenge. Many studies have suggested that a large proportion of patients may have active inflammation, but normal inflammatory markers. Although various disease activity scores have been validated, most rely to a large degree on biomarkers such as CRP and ESR. In this study, we examine the utility and limitations of these biomarkers, as well as the DAS28-CRP in appraising disease activity in RA. Methods: Two hundred and twenty three consecutive rheumatoid arthritis reporting knee arthralgia underwent synovial sampling of the affected knee via needle arthroscopy. The synovium was examined by microscopy with H+E staining as well as immunohistochemistry, and related to the ESR, CRP and DAS28-CRP on blood samples taken immediately before arthroscopy. Results: Although a statistically significant positive correlation was observed between CRP and the level of inflammation in the biopsy retrieved (n = 197, rho = 0.43, CI 0.30-0.54, p < 0.0001), there was histological evidence of inflammation in the synovium in 49.4% of the patients who had a normal CRP. A positive correlation was also observed between ESR and the level of inflammation in the biopsy retrieved (n = 188, rho = 0.29, CI 0.15-0.42 p < 0.0001). A statistically significant but weak positive correlation was observed between the DAS28-CRP and synovial inflammation (n = 189, rho = 0.23, CI 0.09-0.37, p = 0.0011). Only the CD19 infiltrate in the synovium correlated with serum CRP (n = 70, rho = 0.32, CI 0.08-0.52, p = 0.0068). Conclusion: CRP has a moderately strong relationship with disease activity, but there are significant pitfalls in the use of this biomarker in RA, and therefore a need interpret CRP results judiciously. The results of this study underline the heterogeneity of RA, and the need to develop improved panels of biomarkers, to better stratify RA, and to identify the cohort for whom inflammatory activity cannot be measured accurately with CRP.

Oxidative stress impairs energy metabolism in primary cells and synovial tissue of patients with rheumatoid arthritis.

BACKGROUND: In this study, we examined the effect of oxidative stress on cellular energy metabolism and pro-angiogenic/pro-inflammatory mechanisms of primary rheumatoid arthritis synovial fibroblast cells (RASFC) and human umbilical vein endothelial cells (HUVEC). METHODS: Primary RASFC and HUVEC were cultured with the oxidative stress inducer 4-hydroxy-2-nonenal (4-HNE), and extracellular acidification rate, oxygen consumption rate, mitochondrial function and pro-angiogenic/pro-inflammatory mechanisms were assessed using the Seahorse analyser, complex I-V activity assays, random mutation mitochondrial capture assays, enzyme-linked immunosorbent assays and functional assays, including angiogenic tube formation, migration and invasion. Expression of angiogenic growth factors in synovial tissue (ST) was assessed by IHC in patients with rheumatoid arthritis (RA) undergoing arthroscopy before and after administration of tumour necrosis factor inhibitors (TNFi). RESULTS: In RASFC and HUVEC, 4-HNE-induced oxidative stress reprogrammed energy metabolism by inhibiting mitochondrial basal, maximal and adenosine triphosphate-linked respiration and reserve capacity, coupled with the reduced enzymatic activity of oxidative phosphorylation complexes III and IV. In contrast, 4-HNE elevated basal glycolysis, glycolytic capacity and glycolytic reserve, paralleled by an increase in mitochondrial DNA mutations and reactive oxygen species. 4-HNE activated pro-angiogenic responses of RASFC, which subsequently altered HUVEC invasion and migration, angiogenic tube formation and the release of pro-angiogenic mediators. In vivo markers of angiogenesis (vascular endothelial growth factor, angiopoietin 2 [Ang2], tyrosine kinase receptor [Tie2]) were significantly associated with oxidative damage and oxygen metabolism in the inflamed synovium. Significant reduction in ST vascularity and Ang2/Tie2 expression was demonstrated in patients with RA before and after administration of TNFi. CONCLUSIONS: Oxidative stress promotes metabolism in favour of glycolysis, an effect that may contribute to acceleration of inflammatory mechanisms and subsequent dysfunctional angiogenesis in RA.

Tumour vasculature immaturity, oxidative damage and systemic inflammation stratify survival of colorectal cancer patients on bevacizumab treatment.

Despite treatment of patients with metastatic colorectal cancer (mCRC) with bevacizumab plus chemotherapy, response rates are modest and there are no biomarkers available that will predict response. The aim of this study was to assess if markers associated with three interconnected cancer-associated biological processes, specifically angiogenesis, inflammation and oxidative damage, could stratify the survival outcome of this cohort. Levels of angiogenesis, inflammation and oxidative damage markers were assessed in pre-bevacizumab resected tumour and serum samples of mCRC patients by dual immunofluorescence, immunohistochemistry and ELISA. This study identified that specific markers of angiogenesis, inflammation and oxidative damage stratify survival of patients on this anti-angiogenic treatment. Biomarkers of immature tumour vasculature (% IMM, p=0.026, n=80), high levels of oxidative damage in the tumour epithelium (intensity of 8-oxo-dG in nuclear and cytoplasmic compartments, p=0.042 and 0.038 respectively, n=75) and lower systemic pro-inflammatory cytokines (IL6 and IL8, p=0.053 and 0.049 respectively, n=61) significantly stratify with median overall survival (OS). In summary, screening for a panel of biomarkers for high levels of immature tumour vasculature, high levels of oxidative DNA damage and low levels of systemic pro-inflammatory cytokines may be beneficial in predicting enhanced survival outcome following bevacizumab treatment for mCRC.

Synovial Immunophenotype and Anti-Citrullinated Peptide Antibodies in Rheumatoid Arthritis Patients: Relationship to Treatment Response and Radiologic Prognosis.

OBJECTIVE: Serum anti-citrullinated peptide antibodies (ACPAs) may be present before the development of rheumatoid arthritis (RA) and may be predictive of more severe, erosive disease. This study was undertaken to examine the synovial tissue immunophenotype according to ACPA status in patients with RA, as well as the response to treatment and erosion status. METHODS: Consecutive RA patients were prospectively recruited and underwent clinical and serologic assessments before and after treatment. Radiologic assessment was performed at the time of clinical follow-up. Synovial tissue was immunostained for specific markers of B cells (CD19), T cells (CD3, CD4, and CD8), macrophages (CD68), and blood vessels (factor VIII). Serum CXCL13 levels were quantified by enzyme-linked immunosorbent assay. Synovial tissue sections were analyzed for immunophenotype according to ACPA status, using a validated semiquantitative scoring method, and also analyzed for the presence of lymphoid aggregates. Response to treatment with nonbiologic or biologic disease-modifying antirheumatic drugs was assessed using the European League Against Rheumatism (EULAR) response criteria. RESULTS: In total, 123 subjects (78 ACPA+) were included. Compared to ACPA- RA patients, synovium from ACPA+ RA patients was characterized by significantly higher levels of CD19+ B cells and CD3+ and CD8+ T cells (each P < 0.05), and CD19+ B cell levels were significantly higher in patients who were naive to treatment. The CD19+ B cell infiltrate level was higher in patients with erosions at follow-up (P = 0.0128). Levels of lymphoid aggregates of CD19+ B cells were significantly higher in ACPA+ patients (P < 0.05), and this was associated with increased serum CXCL13 levels. The EULAR response was significantly associated with the level of CD3+ T cell infiltrates (P < 0.05), while CD68+ macrophage and CD8+ T cell levels were predictive of the response to tumor necrosis factor inhibitors (P < 0.05). CONCLUSION: The results of this prospective study demonstrate that the levels of synovial B cell infiltrates and lymphoid aggregates were significantly higher in ACPA+ RA patients, especially those who were naive to treatment. In addition, ACPA+ subjects developed more erosions during progression of the disease and had higher serum levels of CXCL13. The EULAR response to therapy in ACPA+ RA patients was associated with increased levels of T cell and macrophage markers.

Resolution of TLR2-induced inflammation through manipulation of metabolic pathways in Rheumatoid Arthritis.

During inflammation, immune cells activated by toll-like receptors (TLRs) have the ability to undergo a bioenergetic switch towards glycolysis in a manner similar to that observed in tumour cells. While TLRs have been implicated in the pathogenesis of rheumatoid arthritis (RA), their role in regulating cellular metabolism in synovial cells, however, is still unknown. In this study, we investigated the effect of TLR2-activation on mitochondrial function and bioenergetics in primary RA-synovial fibroblast cells (RASFC), and further determined the role of glycolytic blockade on TLR2-induced inflammation in RASFC using glycolytic inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO). We observed an increase in mitochondrial mutations, ROS and lipid peroxidation, paralleled by a decrease in the mitochondrial membrane potential in TLR2-stimulated RASFC. This was mirrored by differential regulation of key mitochondrial genes, coupled with alteration in mitochondrial morphology. TLR2-activation also regulated changes in the bioenergetic profile of RASFC, inducing PKM2 nuclear translocation, decreased mitochondrial respiration and ATP synthesis and increased glycolysis:respiration ratio, suggesting a metabolic switch. Finally, using 3PO, we demonstrated that glycolytic blockade reversed TLR2-induced pro-inflammatory mechanisms including invasion, migration, cytokine/chemokine secretion and signalling pathways. These findings support the concept of complex interplay between innate immunity, oxidative damage and oxygen metabolism in RA pathogenesis.

Hypoxia, mitochondrial dysfunction and synovial invasiveness in rheumatoid arthritis.

Synovial proliferation, neovascularization and leukocyte extravasation transform the normally acellular synovium into an invasive tumour-like 'pannus'. The highly dysregulated architecture of the microvasculature creates a poor oxygen supply to the synovium, which, along with the increased metabolic turnover of the expanding synovial pannus, creates a hypoxic microenvironment. Abnormal cellular metabolism and mitochondrial dysfunction thus ensue and, in turn, through the increased production of reactive oxygen species, actively induce inflammation. When exposed to hypoxia in the inflamed joint, immune-inflammatory cells show adaptive survival reactions by activating key proinflammatory signalling pathways, including those mediated by hypoxia-inducible factor-1α (HIF-1α), nuclear factor κB (NF-κB), Janus kinase-signal transducer and activator of transcription (JAK-STAT) and Notch, which contribute to synovial invasiveness. The reprogramming of hypoxia-mediated pathways in synovial cells, such as fibroblasts, dendritic cells, macrophages and T cells, is implicated in the pathogenesis of rheumatoid arthritis and other inflammatory conditions, and might therefore provide an opportunity for therapeutic intervention.

Redox-mediated angiogenesis in the hypoxic joint of inflammatory arthritis.

OBJECTIVE: Inflammatory arthritis is associated with joint inflammation, synovial tissue proliferation, and degradation of articular cartilage and bone. Angiogenesis is an early and fundamental component of synovial inflammation. Oxygen metabolism is recognized as an important mediator of joint vascular remodeling. The aim of this study was to determine whether in vivo synovial hypoxia (tissue PO2 [tPO2 ]) and tumor necrosis factor (TNF) blocking therapy alter synovial vascular expression of NADPH oxidase (NOX) and how this action regulates angiogenic mechanisms. METHODS: NOX-2 protein and messenger RNA expression was examined in patients with inflammatory arthritis before and after receiving TNF inhibitor (TNFi) therapy and in mice with collagen-induced arthritis (CIA). Proangiogenic processes were assessed in human microvascular endothelial cells (HMVECs) following culture with NOX-2 activators (TNFα and 4-hydroxynonenal), small interfering RNA (siRNA) for NOX, and the inhibitor diphenyleneiodonium (DPI) under conditions of normoxia or 3% hypoxia. RESULTS: We demonstrated significantly increased NOX-2 expression in the joints of patients with inflammatory arthritis and the joints of mice with CIA as compared to controls. NOX-2 expression was higher in patients with synovial tPO2 levels <3% than in those with tPO2 levels >3% (P < 0.05), and correlated with in vivo macroscopic/microscopic measures of angiogenesis, such as vascularity and levels of vascular endothelial growth factor, angiopoietin 2, factor VIII, neural cell adhesion molecule, and α-smooth muscle actin (P < 0.05 for all). A decrease in NOX-2 expression was paralleled by an increase in in vivo tPO2 levels only in those patients who were defined as TNFi responders. In vitro NOX-2 activators and 3% hypoxia significantly promoted HMVEC migration, angiogenic tube formation, and secretion of proangiogenic mediators, effects that were blocked by siRNA for NOX-2 or the NOX-2 inhibitor DPI. CONCLUSION: We demonstrated that hypoxia activates NOX-2 protein expression, and NOX-2-induced oxidative stress may be an initiating factor in driving angiogenesis.

Notch-1 mediates endothelial cell activation and invasion in psoriasis.

Notch receptor-ligand interactions are critical for cell proliferation, differentiation and survival; however, the role of Notch signalling in psoriasis remains to be elucidated. Serum amyloid A (A-SAA) is an acute-phase protein with cytokine-like properties, regulates cell survival pathways and is implicated in many inflammatory conditions. To examine the role of Notch-1 signalling in the pathogenesis of psoriasis, Notch-1, DLL-4, Jagged-1, Hrt-1/Hrt-2, A-SAA, Factor VIII and vascular endothelial growth factor (VEGF) mRNA and/or protein expression in psoriasis skin biopsies, serum and dHMVEC were assessed by immunohistology, dual-immunofluorescence, real-time PCR, ELISA and Western blotting. A-SAA-induced angiogenesis and invasion in the presence of Notch-1 siRNA was assessed by matrigel tube formation assays and Transwell invasion assay. Increased Notch-1, its ligand DLL-4 and Hrt-1 expression were demonstrated in lesional skin compared with non-lesional skin, with greatest expression observed in the dermal vasculature (P < 0.05). Dual-immunofluorescent staining demonstrated co-localization of Notch-1 to endothelial cell marker Factor VIII. A significant increase in A-SAA levels was demonstrated in psoriasis serum compared with healthy control serum (P < 0.05), and A-SAA expression was higher in lesional skin compared with non-lesional. In dHMVEC, A-SAA significantly induced Jagged-1, Hrt-1 and VEGF mRNA expression (P < 0.05) and activated Notch-1 IC indicative of transcriptional regulation. In contrast, A-SAA significantly inhibited DLL-4 mRNA expression (P < 0.05). Finally A-SAA-induced angiogenesis and invasion were inhibited by Notch-1 siRNA (P < 0.05). Notch receptor-ligand interactions mediate vascular dysfunction in psoriasis and may represent a potential therapeutic target.

Inhibition of dendritic cell maturation by the tumor microenvironment correlates with the survival of colorectal cancer patients following bevacizumab treatment.

Development of bevacizumab has improved survival in colorectal cancer, however, currently there are no biomarkers that predict response to bevacizumab and it is unknown how it influences the immune system in colorectal cancer patients. Dendritic cells are important for the induction of an antitumor immune response; however tumors are capable of disabling dendritic cells and escaping immune surveillance. The aim of this study was to assess the numbers of CD11c+ cells infiltrating tumor tissue and to examine the effects of tumor conditioned media (TCM) and bevacizumab conditioned media (BCM) on dendritic cell maturation and correlate our findings with patient survival. colorectal cancer explant tissues were cultured with or without bevacizumab, to generate BCM and TCM, which were used to treat dendritic cells. CD80, CD86, CD83, CD54, HLA-DR, and CD1d expression was measured by flow cytometry. Interleukin (IL)-10 and IL-12p70 were measured by ELISA. The Cox proportional hazards model was used to associate survival with dendritic cell inhibition. TCM and BCM inhibited lipopolysaccharide (LPS)-induced dendritic cell maturation and IL-12p70 secretion (P < 0.0001), while increasing IL-10 secretion (P = 0.0033 and 0.0220, respectively). Inhibition of LPS-induced CD1d (P = 0.021, HR = 1.096) and CD83 (P = 0.017, HR = 1.083) by TCM and inhibition of CD1d (P = 0.017, HR = 1.067), CD83 (P = 0.032, HR = 1.035), and IL-12p70 (P = 0.037, HR = 1.036) by BCM was associated with poor survival in colorectal cancer patients. CD11c expression was elevated in tumor tissue compared with normal tissue (P < 0.001), but this did not correlate with survival. In conclusion, TCM and BCM inhibit dendritic cells, and this inhibition correlates with survival of colorectal cancer patients receiving bevacizumab.

Mitochondrial mutagenesis correlates with the local inflammatory environment in arthritis.

BACKGROUND: To examine the association between mitochondrial mutagenesis and the proinflammatory microenvironment in patients with inflammatory arthritis. METHODS: Fifty patients with inflammatory arthritis underwent arthroscopy and synovial tissue biopsies, synovial fluid and clinical assessment were obtained. Fifteen patients pre/post-TNFi therapy were also recruited. Normal synovial biopsies were obtained from 10 subjects undergoing interventional arthroscopy. Macroscopic synovitis/vascularity was measured by visual analogue scale. Cell-specific markers CD3 (T cells) and CD68 (macrophages) were quantified by immunohistology. TNFα, IL-6, IFNγ and IL-1ß were measured in synovial fluids by MSD multiplex assays. Synovial tissue mitochondrial mutagenesis was quantified using a mitochondrial random mutation capture assay (RMCA). The direct effect of TNFα on oxidative stress and mitochondrial function was assessed in primary cultures of rheumatoid arthritis synovial fibroblast cells (RASFCs). Mitochondrial mutagenesis, reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and mitochondrial mass (MM) were quantified using the RMCA and specific cell fluorescent probes. RESULTS: A significant increase in mtDNA mutation frequency was demonstrated in inflamed synovial tissue compared with control (p<0.05), an effect that was independent of age. mtDNA mutations positively correlated with macroscopic synovitis (r=0.52, p<0.016), vascularity (r=0.54, p<0.01) and with synovial fluid cytokine levels of TNFα (r=0.74, p<0.024) and IFNγ (r=0.72, p<0.039). mtDNA mutation frequency post-TNFi therapy was significantly lower in patients with a DAS<3.2 (p<0.05) and associated with clinical and microscopic measures of disease (p<0.05). In vitro TNFα significantly induced mtDNA mutations, ROS, MM and MMP in RASFCs (all p<0.05). CONCLUSION: High mitochondrial mutations are strongly associated with synovial inflammation showing a direct link between mitochondrial mutations and key proinflammatory pathways.

Successful tumour necrosis factor (TNF) blocking therapy suppresses oxidative stress and hypoxia-induced mitochondrial mutagenesis in inflammatory arthritis.

INTRODUCTION: To examine the effects of tumour necrosis factor (TNF) blocking therapy on the levels of early mitochondrial genome alterations and oxidative stress. METHODS: Eighteen inflammatory arthritis patients underwent synovial tissue oxygen (tpO(2)) measurements and clinical assessment of disease activity (DAS28-CRP) at baseline (T0) and three months (T3) after starting biologic therapy. Synovial tissue lipid peroxidation (4-HNE), T and B cell specific markers and synovial vascular endothelial growth factor (VEGF) were quantified by immunohistochemistry. Synovial levels of random mitochondrial DNA (mtDNA) mutations were assessed using Random Mutation Capture (RMC) assay. RESULTS: 4-HNE levels pre/post anti TNF-α therapy were inversely correlated with in vivo tpO(2) (P < 0.008; r = -0.60). Biologic therapy responders showed a significantly reduced 4-HNE expression (P < 0.05). High 4-HNE expression correlated with high DAS28-CRP (P = 0.02; r = 0.53), tender joint count for 28 joints (TJC-28) (P = 0.03; r = 0.49), swollen joint count for 28 joints (SJC-28) (P = 0.03; r = 0.50) and visual analogue scale (VAS) (P = 0.04; r = 0.48). Strong positive association was found between the number of 4-HNE positive cells and CD4+ cells (P = 0.04; r = 0.60), CD8+ cells (P = 0.001; r = 0.70), CD20+ cells (P = 0.04; r = 0.68), CD68+ cells (P = 0.04; r = 0.47) and synovial VEGF expression (P = 0.01; r = 063). In patients whose in vivo tpO(2) levels improved post treatment, significant reduction in mtDNA mutations and DAS28-CRP was observed (P < 0.05). In contrast in those patients whose tpO2 levels remained the same or reduced at T3, no significant changes for mtDNA mutations and DAS28-CRP were found. CONCLUSIONS: High levels of synovial oxidative stress and mitochondrial mutation burden are strongly associated with low in vivo oxygen tension and synovial inflammation. Furthermore these significant mitochondrial genome alterations are rescued following successful anti TNF-α treatment.

Tumor necrosis factor blocking therapy alters joint inflammation and hypoxia.

OBJECTIVE: To examine the effect of tumor necrosis factor (TNF) blocking therapy on hypoxia in vivo, macroscopic and microscopic inflammation, and magnetic resonance imaging (MRI) results in patients with inflammatory arthritis. METHODS: Patients with inflammatory arthritis (n = 20) underwent full clinical assessment, arthroscopy, synovial biopsy, and MRI before and after initiation of biologic therapy. Macroscopic synovitis/vascularity was assessed with a visual analog scale, and tissue PO(2) (tPO(2) ) was measured at arthroscopy using a Licox probe. Cell-specific markers (CD4, CD8, CD68, CD20, and CD19) and blood vessel maturity were quantified by immunohistologic analysis and dual-immunofluorescence factor VIII/α-smooth muscle actin staining, respectively. Contiguous gadoteric acid-enhanced MRI of the target knee was used to assess synovial enhancement. RESULTS: Biologic therapy responders showed a significant increase of tPO(2) in vivo (P < 0.05). This response was associated with significant reductions in 28-joint Disease Activity Score using the C-reactive protein level (DAS28-CRP) (P = 0.012), macroscopic synovitis (P = 0.017), macroscopic vascularity (P = 0.05), CD4+ T cells (P < 0.041), and CD68+ macrophages (P < 0.011). Blood vessel numbers were also reduced in responders; however, this did not reach statistical significance. Strong inverse correlations were demonstrated between changes in tPo(2) levels and changes in DAS28-CRP (r = -0.53, P < 0.001), CD4 (r = -0.44, P < 0.026), CD68 (r = -0.46, P < 0.003), and macroscopic vascularity (r = -0.314, P = 0.049) after therapy. Furthermore, changes in inflammation as measured by MRI showed a strong inverse correlation with tPO(2) levels (r = -0.688, P < 0.002) and positive correlations with CRP levels (r = 0.707, P = 0.001), macroscopic synovitis (r = 0.457, P = 0.056), macroscopic vascularity (r = 0.528, P= 0.017), CD4 (r = 0.553, P < 0.032), and CD68 (r = 0.670, P < 0.002) after therapy. CONCLUSION: This is the first study to show that successful biologic therapy significantly improves in vivo synovial hypoxia. Changes are strongly associated with changes in macroscopic and microscopic measures of joint inflammation and MRI improvement. These data further strengthen the concept that hypoxia is an important event driving synovial inflammation.

Oxidative damage in synovial tissue is associated with in vivo hypoxic status in the arthritic joint.

OBJECTIVES: To assess levels of oxidative DNA damage (8-oxo-7,8-dihydro-2'-deoxyguanine; 8-oxo-dG) and lipid peroxidation (4-hydroxy-2-nonenal; 4-HNE) in serum, synovial fluid and tissue of patients with inflammatory arthritis in relation to in vivo hypoxia levels, disease activity and angiogenic markers. METHODS: Oxygen levels in synovial tissue were assessed using an oxygen/temperature probe. Nuclear and cytoplasmic 8-oxo-dG and 4-HNE levels were assessed in synovial tissue from 23 patients by immunohistochemistry. 8-Oxo-dG and 4-HNE levels in serum and synovial fluid were determined using 8-oxo-dG and hexanoyl-Lys (HEL) adduct ELISAs, respectively. Serum vascular endothelial growth factor (VEGF) and angiopoietin 2 (Ang2) levels were also measured by ELISA. RESULTS: The median oxygen tension in synovial tissue was profoundly hypoxic at 19.35 mm Hg (2.5%). Nuclear 8-oxo-dG levels were significantly higher than nuclear 4-HNE levels in the lining and sublining layers (all p<0.001). In contrast, cytoplasmic 4-HNE levels were higher than cytoplasmic 8-oxo-dG levels in both cell layers (all p<0.001). Reduced in vivo oxygen tension correlated with high lipid peroxidation in synovial fluid (p=0.027; r=0.54) and tissue (p=0.004; r=0.58). Serum VEGF levels were positively correlated with cytoplasmic 4-HNE expression (p=0.05; r=0.43) and intensity (p=0.006; r=0.59) in the lining layer. Serum Ang2 levels were positively correlated with nuclear 4-HNE expression and intensity in both cell layers (all p < or = 0.05). DAS28-C-reactive protein was correlated with nuclear 4-HNE expression in the sublining layer (p=0.02; r=0.48) and DAS28-erythrocyte sedimentation rate was correlated with nuclear 4-HNE expression in both cell layers (p < or = 0.03). CONCLUSIONS: Lipid peroxidation is associated with low oxygen tension in vivo, disease activity and angiogenic marker expression in inflammatory arthritis.