A flow cytometric analysis of vitreous inflammatory cells in patients with proliferative diabetic retinopathy

hsa_circ_0087100/hsa-miR-6743-5p affects Th1 cell differentiation by regulating STAT1 in diabetic retinopathy

Objective: To elucidate the role of the competitive endogenous RNA (ceRNA) network in immune infiltration of diabetic retinopathy (DR). Methods: We obtained differentially expressed (DE) circRNAs, miRNAs and mRNAs from the Gene Expression Omnibus database. Then, we identified immune infiltration by CIBERSORT and single-sample gene set enrichment analysis and discovered co-expression genes by weighted gene co-expression network analysis. Furthermore, STAT1-mediated Th1 differentiation was determined in DR cell models, DR patients and DR mouse models. Results: hsa_circ_0087100/hsa-miR-6743-5p/STAT1 was involved in immune infiltration of Th1 cells. Aberrant expression of the ceRNA network and STAT1-mediated Th1 differentiation was thus verified in vitro and in vivo. Conclusion: hsa_circ_0087100/hsa-miR-6743-5p/STAT1 may affect Th1 cell differentiation in DR.

A single cell atlas of circulating immune cells involved in diabetic retinopathy

This study focused on examining the exact role of circulating immune cells in the development of diabetic retinopathy (DR). In vitro co-culture experiments showed that peripheral blood mononuclear cells (PBMCs) from patients with type 1 DR crucially modulated the biological functions of human retinal microvascular endothelial cells (HRMECs), consequently disrupting their normal functionality. Single-cell RNA sequencing (scRNA-seq) study revealed unique differentially expressed genes and pathways in circulating immune cells among healthy controls, non-diabetic retinopathy (NDR) patients, and DR patients. Of significance was the observed upregulation of JUND in each subset of PBMCs in patients with type 1 DR. Further studies showed that downregulating JUND in DR patient-derived PBMCs led to the amelioration of HRMEC dysfunction. These findings highlighted the notable alterations in the transcriptomic patterns of circulating immune cells in type 1 DR patients and underscored the significance of JUND as a key factor for PBMCs in participating in the pathogenesis of DR.

Are intravitreal hyperreflective particles alike in eyes with acute toxoplasma chorioretinitis and non-infectious uveitis?

BACKGROUND

To compare distinctive features of hyperreflective particles observed on spectral-domain optical coherence tomography (OCT) sections in eyes with acute toxoplasma chorioretinitis (TC) and non-infectious uveitis (NIU).

METHODS

Medical records and the spectral-domain OCT images of the patients with TC and NIU were retrospectively reviewed. The TC and NIU groups were compared in terms of age, sex, mean OCT image quality, mean central macular thickness (CMT), presence of intraretinal fluid (IRF), presence of subretinal fluid (SRF), number of hyperreflective particles in the posterior vitreous area and mean particle measurement in the posterior vitreous area.

RESULTS

Non-infectious uveitis group included nine patients (60 %) with Behcet's uveitis, five patients (33.3 %) with idiopathic posterior uveitis or panuveitis, and the remaining patient (6.7 %) with HLA-B27 associated uveitis. Comparison of the mean age, sex distribution, mean OCT image quality, mean CMT, presence of IRF, presence of SRF and the mean number of hyperreflective particles in the posterior vitreous area between the two groups showed no statistically significant differences (p = 0.085, p = 0.051, p = 0.748, p = 0.431, p = 0.109, p = 0.080 and p = 0.152, respectively). However, the mean length of the hyperreflective particles in the posterior vitreous area was 27.22 ± 8.60 μm in the TC group, and 21.91 ± 3.58 μm in the NIU group, with a significant difference between the two groups (p = 0.036).

CONCLUSION

This pilot study aimed to assess the hyperreflective particles in the posterior vitreous area using spectral-domain OCT images and image processing software. Despite its limitations, such as the small sample size, limited understanding of the nature of hyperreflective particles, and the absence of differentiation between acute and chronic uveitis, our study points out the potential role of the measurement of the hyperreflective particle length located in the posterior vitreous in differentiating the acute infectious versus non-infectious uveitis as the hyperreflective particles tend to be larger in infectious cases.

CD40 Upregulation in the Retina of Patients With Diabetic Retinopathy: Association With TRAF2/TRAF6 Upregulation and Inflammatory Molecule Expression

Purpose

CD40 is upregulated in the retinas of diabetic mice, drives pro-inflammatory molecule expression, and promotes diabetic retinopathy. The role of CD40 in diabetic retinopathy in humans is unknown. Upregulation of CD40 and its downstream signaling molecules TNF receptor associated factors (TRAFs) is a key feature of CD40-driven inflammatory disorders. We examined the expression of CD40, TRAF2, and TRAF6 as well as pro-inflammatory molecules in retinas from patients with diabetic retinopathy.

Methods

Posterior poles from patients with diabetic retinopathy and non-diabetic controls were stained with antibodies against von Willebrand factor (labels endothelial cells), cellular retinaldehyde-binding protein (CRALBP), or vimentin (both label Müller cells) plus antibodies against CD40, TRAF2, TRAF6, ICAM-1, CCL2, TNF-α, and/or phospho-Tyr783 phospholipase Cγ1 (PLCγ1). Sections were analyzed by confocal microscopy.

Results

CD40 expression was increased in endothelial and Müller cells from patients with diabetic retinopathy. CD40 was co-expressed with ICAM-1 in endothelial cells and with CCL2 in Müller cells. TNF-α was detected in retinal cells from these patients, but these cells lacked endothelial/Müller cell markers. CD40 in Müller cells from patients with diabetic retinopathy co-expressed activated phospholipase Cγ1, a molecule that induces TNF-α expression in myeloid cells in mice. CD40 upregulation in endothelial cells and Müller cells from patients with diabetic retinopathy was accompanied by TRAF2 and TRAF6 upregulation.

Conclusions

CD40, TRAF2, and TRAF6 are upregulated in patients with diabetic retinopathy. CD40 associates with expression of pro-inflammatory molecules. These findings suggest that CD40-TRAF signaling may promote pro-inflammatory responses in the retinas of patients with diabetic retinopathy.

CD8+ T Cells Promote Pathological Angiogenesis in Ocular Neovascular Disease

BACKGROUND

CD4⁺ (cluster of differentation) and CD8⁺ T cells are increased in the ocular fluids of patients with neovascular retinopathy, yet their role in the disease process is unknown.

METHODS

We describe how CD8⁺ T cells migrate into the retina and contribute to pathological angiogenesis by releasing cytokines and cytotoxic factors.

RESULTS

In oxygen-induced retinopathy, flow cytometry revealed the numbers of CD4⁺ and CD8⁺ T cells were increased in blood, lymphoid organs, and retina throughout the development of neovascular retinopathy. Interestingly, the depletion of CD8⁺ T cells but not CD4⁺ T cells reduced retinal neovascularization and vascular leakage. Using reporter mice expressing gfp (green fluorescence protein) in CD8⁺ T cells, these cells were localized near neovascular tufts in the retina, confirming that CD8⁺ T cells contribute to the disease. Furthermore, the adoptive transfer of CD8⁺ T cells deficient in TNF (tumor necrosis factor), IFNγ (interferon gamma), Prf (perforin), or GzmA/B (granzymes A/B) into immunocompetent Rag1^-/- mice revealed that CD8⁺ T cells mediate retinal vascular disease via these factors, with TNF influencing all aspects of vascular pathology. The pathway by which CD8⁺ T cells migrate into the retina was identified as CXCR3 (C-X-C motif chemokine receptor 3) with the CXCR3 blockade reducing the number of CD8⁺ T cells within the retina and retinal vascular disease.

CONCLUSIONS

We discovered that CXCR3 is central to the migration of CD8⁺ T cells into the retina as the CXCR3 blockade reduced the number of CD8⁺ T cells within the retina and vasculopathy. This research identified an unappreciated role for CD8⁺ T cells in retinal inflammation and vascular disease. Reducing CD8⁺ T cells via their inflammatory and recruitment pathways is a potential treatment for neovascular retinopathies.

Finerenone, a Non-Steroidal Mineralocorticoid Receptor Antagonist, Reduces Vascular Injury and Increases Regulatory T-Cells: Studies in Rodents with Diabetic and Neovascular Retinopathy

Vision loss in diabetic retinopathy features damage to the blood-retinal barrier and neovascularization, with hypertension and the renin-angiotensin system (RAS) having causal roles. We evaluated if finerenone, a non-steroidal mineralocorticoid receptor (MR) antagonist, reduced vascular pathology and inflammation in diabetic and neovascular retinopathy. Diabetic and hypertensive transgenic (mRen-2)27 rats overexpressing the RAS received the MR antagonist finerenone (10 mg/kg/day, oral gavage) or the angiotensin-converting enzyme inhibitor perindopril (10 mg/kg/day, drinking water) for 12 weeks. As retinal neovascularization does not develop in diabetic rodents, finerenone (5 mg/kg/day, i.p.) was evaluated in murine oxygen-induced retinopathy (OIR). Retinal vasculopathy was assessed by measuring gliosis, vascular leakage, neovascularization, and VEGF. Inflammation was investigated by quantitating retinal microglia/macrophages, pro-inflammatory mediators, and anti-inflammatory regulatory T-cells (Tregs). In diabetes, both treatments reduced systolic blood pressure, gliosis, vascular leakage, and microglial/macrophage density, but only finerenone lowered VEGF, ICAM-1, and IL-1ß. In OIR, finerenone reduced neovascularization, vascular leakage, and microglial density, and increased Tregs in the blood, spleen, and retina. Our findings, in the context of the FIDELIO-DKD and FIGARO-DKD trials reporting the benefits of finerenone on renal and cardiovascular outcomes in diabetic kidney disease, indicate the potential of finerenone as an effective oral treatment for diabetic retinopathy.

CD8+T Cell-Related Gene Biomarkers in Macular Edema of Diabetic Retinopathy

BACKGROUND

CD8+T lymphocytes have a strong pro-inflammatory effect in all parts of the tissue, and some studies have demonstrated that its concentration in the vitreous increased significantly, suggesting that CD8+T cells play a pivotal role in the inflammatory response of diabetic retinopathy (DR). However, the infiltration of CD8+T cells in the DR retina, especially in diabetic macular edema (DME), and its related genes are still unclear.

METHODS

Download the GSE16036 dataset from the Gene Expression Omnibus (GEO) database. The ImmuCellAI program was performed to evaluate the abundance of 24 immune cells including CD8+T cells. The CD8+T cell-related genes (DECD8+TRGs) between non-proliferative diabetic retinopathy (NPDR) and DME were detected via difference analysis and correlation analysis. Enrichment analysis and protein-protein interaction (PPI) network mapping were implemented to explore the potential function of DECD8+TRGs. Lasso regression, support vector machine recursive feature elimination (SVM-RFE), CytoHubba plug-in and MCODE plug-in in Cytoscape software, and Weighted Gene Co-Expression Network Analysis (WGCNA) were performed to comprehensively analyze and obtain Hub DECD8+TRGs. Hub DECD8+TRGs expression patterns were further validated in other two DR-related independent datasets. The CD8+TRG score was defined as the genetic characterization of Hub DECD8+TRGs using the GSVA sample scoring method, which can be administered to distinguish early and advanced diabetic nephropathy (DN) as well as normal and DN. Finally, the transcription level of DECD8+TRGs in DR model mouse were verified by quantitative real-time PCR (qPCR).

RESULTS

A total of 371 DECD8+TRGs were identified, of which 294 genes were positively correlated and only 77 genes were negatively correlated. Eight genes (IKZF1, PTPRC, ITGB2, ITGAX, TLR7, LYN, CD74, SPI1) were recognized as Hub DECD8+TRGs. DR and DN, which have strong clinical correlation, have been proved to be associated with CD8+T cell-related hub genes by multiple independent data sets. Hub DECD8+TRGs can not only distinguish PDR from normal and DN from normal, but also play a role in the early and progressive stages of the two diseases (NPDR vs DME, Early DN vs Advanced DN). The qPCR transcription level and trend of Hub DECD8+TRGs in DR mouse model was basically the same as that in human transcriptome.

CONCLUSION

This study not only increases our understanding of the molecular mechanism of CD8+T cells in the progression of DME, but also expands people's cognitive vision of the molecular mechanism of crosstalk of CD8+T cells in the eyes and kidneys of patients with diabetes.

The role of inflammation and neurodegeneration in diabetic macular edema

The pathogenesis of diabetic macular edema (DME) is complex. Persistently high blood glucose activates multiple cellular pathways and induces inflammation, oxidation stress, and vascular dysfunction. Retinal ganglion cells, macroglial and microglial cells, endothelial cells, pericytes, and retinal pigment epithelium cells are involved. Neurodegeneration, characterized by dysfunction or apoptotic loss of retinal neurons, occurs early and independently from the vascular alterations. Despite the increasing knowledge on the pathways involved in DME, only limited therapeutic strategies are available. Besides antiangiogenic drugs and intravitreal corticosteroids, alternative therapeutic options tackling inflammation, oxidative stress, and neurodegeneration have been considered, but none of them has been currently approved.

Immune function in X-linked retinoschisis subjects in an AAV8-RS1 phase I/IIa gene therapy trial

This study explored systemic immune changes in 11 subjects with X-linked retinoschisis (XLRS) in a phase I/IIa adeno-associated virus 8 (AAV8)-RS1 gene therapy trial (ClinicalTrials.gov: NCT02317887). Immune cell proportions and serum analytes were compared to 12 healthy male controls. At pre-dosing baseline the mean CD4/CD8 ratio of XLRS subjects was elevated. CD11c⁺ myeloid dendritic cells (DCs) and the serum epidermal growth factor (EGF) level were decreased, while CD123⁺ plasmacytoid DCs and serum interferon (IFN)-γ and tumor necrosis factor (TNF)-α were increased, indicating that the XLRS baseline immune status differs from that of controls. XLRS samples 14 days after AAV8-RS1 administration were compared with the XLRS baseline. Frequency of CD11b⁺CD11c⁺ DCc was decreased in 8 of 11 XLRS subjects across all vector doses (1e9-3e11 vector genomes [vg]/eye). CD8⁺human leukocyte antigen-DR isotype (HLA-DR)⁺ cytotoxic T cells and CD68⁺CD80⁺ macrophages were upregulated in 10 of 11 XLRS subjects, along with increased serum granzyme B in 8 of 11 XLRS subjects and elevated IFN-γ in 9 of 11 XLRS subjects. The six XLRS subjects with ocular inflammation after vector application gave a modestly positive correlation of inflammation score to their respective baseline CD4/CD8 ratios. This exploratory study indicates that XLRS subjects may exhibit a proinflammatory, baseline immune phenotype, and that intravitreal dosing with AAV8-RS1 leads to systemic immune activation with an increase of activated lymphocytes, macrophages, and proinflammatory cytokines.

Correlations between vitreous cytokine levels and inflammatory cells in fibrovascular membranes of patients with proliferative diabetic retinopathy

Purpose

The purpose of this study was to investigate the levels of cytokines in the vitreous, and their correlation with the density of inflammatory cells in fibrovascular membranes (FVMs) in patients with proliferative diabetic retinopathy (PDR) to evaluate intraocular inflammatory conditions with regard to disease activity.

Methods

Thirty-three patients (33 eyes) with PDR requiring vitreoretinal surgery because of FVMs and tractional detachment were enrolled in the study, and compared with 20 patients (20 eyes) with macular hole (MH; control group). All patients underwent complete ophthalmological examinations before surgery. The activity of the disease was noted in patients with PDR. Samples of vitreous and blood were taken, and cytokine (MCP-1, IL-8, IL-6, VEGF, IL-1β, TNF-α, MIP-1α, MIP-1β, IL-10, and IL-12) levels were measured using cytometric bead array (CBA). Samples of FVMs were analyzed with immunohistochemical methods for the presence of inflammatory cells (CD45+, CD14+, CD3+, CD4+, CD8+, and CD19+ cells), and the numerical areal density was calculated (NA). Spearman's correlation was used to assess the association between variables. The Mann-Whitney test was used to assess the differences between independent groups. The Wilcoxon signed-rank test was used for assessing differences between two related groups. A p value of less than 0.05 was considered statistically significant.

Results

Patients with active PDR had statistically significantly higher levels of MCP-1 (p = 0.003), VEGF (p = 0.009), and IL-8 (p = 0.02) in the vitreous in comparison with those with inactive PDR. CD45+, CD14+, CD3+, CD4+, CD8+, and CD19+ cells were identified in FVMs for patients with PDR. Statistically significantly higher numerical areal density of T lymphocytes (CD3+, CD4+, and CD8+) was demonstrated in patients with active PDR in comparison with patients with inactive PDR. Moderate to strong correlations were found between either MCP-1 or IL-8 in the vitreous, and the numerical areal density of cells (CD45+, CD3+, CD4+, and CD8+) in the FVMs, and weaker between either MCP-1 or IL-8 in the vitreous and the numerical areal density of CD14+ cells in the FVMs.

Conclusions

The correlation of cytokine (MCP-1 and IL-8) vitreous levels with the density of inflammatory cells in FVMs, and differences in cytokine levels in the vitreous between patients with active and inactive PDR, and between the vitreous and serum in PDR indicate the importance of local intraocular inflammation in patients with PDR.

Intravitreal pro-inflammatory cytokines in non-obese diabetic mice: Modelling signs of diabetic retinopathy

Diabetic retinopathy is a vascular disease of the retina characterised by hyperglycaemic and inflammatory processes. Most animal models of diabetic retinopathy are hyperglycaemia-only models that do not account for the significant role that inflammation plays in the development of the disease. In the present study, we present data on the establishment of a new animal model of diabetic retinopathy that incorporates both hyperglycaemia and inflammation. We hypothesized that inflammation may trigger and worsen the development of diabetic retinopathy in a hyperglycaemic environment. Pro-inflammatory cytokines, IL-1β and TNF-α, were therefore injected into the vitreous of non-obese diabetic (NOD) mice. CD1 mice were used as same genetic background controls. Fundus and optical coherence tomography images were obtained before (day 0) as well as on days 2 and 7 after intravitreal cytokine injection to assess vessel dilation and beading, retinal and vitreous hyper-reflective foci and retinal thickness. Astrogliosis and microgliosis were assessed using immunohistochemistry. Results showed that intravitreal cytokines induced vessel dilation, beading, severe vitreous hyper-reflective foci, retinal oedema, increased astrogliosis and microglia upregulation in diabetic NOD mice. Intravitreal injection of inflammatory cytokines into the eyes of diabetic mice therefore appears to provide a new model of diabetic retinopathy that could be used for the study of disease progression and treatment strategies.

Myeloperoxidase as an Active Disease Biomarker: Recent Biochemical and Pathological Perspectives

Myeloperoxidase (MPO) belongs to the family of heme-containing peroxidases, produced mostly from polymorphonuclear neutrophils. The active enzyme (150 kDa) is the product of the MPO gene located on long arm of chromosome 17. The primary gene product undergoes several modifications, such as the removal of introns and signal peptides, and leads to the formation of enzymatically inactive glycosylated apoproMPO which complexes with chaperons, producing inactive proMPO by the insertion of a heme moiety. The active enzyme is a homodimer of heavy and light chain protomers. This enzyme is released into the extracellular fluid after oxidative stress and different inflammatory responses. Myeloperoxidase is the only type of peroxidase that uses H₂O₂ to oxidize several halides and pseudohalides to form different hypohalous acids. So, the antibacterial activities of MPO involve the production of reactive oxygen and reactive nitrogen species. Controlled MPO release at the site of infection is of prime importance for its efficient activities. Any uncontrolled degranulation exaggerates the inflammation and can also lead to tissue damage even in absence of inflammation. Several types of tissue injuries and the pathogenesis of several other major chronic diseases such as rheumatoid arthritis, cardiovascular diseases, liver diseases, diabetes, and cancer have been reported to be linked with MPO-derived oxidants. Thus, the enhanced level of MPO activity is one of the best diagnostic tools of inflammatory and oxidative stress biomarkers among these commonly-occurring diseases.

Vascular endothelial growth factor (VEGF)-related single nucleotide polymorphisms rs10738760 and rs6921438 are not associated with diabetic retinopathy (DR) in Slovenian patients with type 2 diabetes mellitus (T2DM)

Diabetic retinopathy (DR) is a complication of diabetes characterized by vascular permeability, increased tissue ischemia, and angiogenesis. One of the most important proteins involved in angiogenesis is vascular endothelial growth factor (VEGF, also known as VEGFA). A previous study demonstrated that two single nucleotide polymorphisms (SNPs), rs6921438 and rs10738760, account for nearly half the variation in circulating VEGF levels. The aim of our study was to assess the association between rs6921438 and rs10738760 and DR in Slovenian patients with type 2 diabetes mellitus (T2DM). This case-control study enrolled 1037 unrelated Slovenian individuals (Caucasians) with T2DM. DR group included 415 T2DM patients with DR, while control group included 622 T2DM patients with no clinical signs of DR. The clinical and laboratory data were obtained from the medical records of the patients. The genotyping of rs6921438 and rs10738760 SNPs was carried out with real-time PCR assays. Significant differences were observed between patients with DR and controls in the duration of diabetes (p < 0.001), insulin therapy (p < 0.001), glycated hemoglobin (p = 0.001), body mass index (p = 0.002), total cholesterol (p = 0.002), and low-density lipoprotein cholesterol (p < 0.001). However, we did not observe significant differences in the genotype and allele distribution of the two SNPs, between DR and control group (p < 0.05). Logistic regression analysis showed that rs6921438 and rs10738760 were not independent genetic risk factors for DR in the co-dominant model adjusted for the above-mentioned clinical and laboratory data. In conclusion, VEGF-related SNPs rs10738760 and rs6921438 are not associated with DR in our group of Slovenian patients (Caucasians) with T2DM.

Algorithm for the Measure of Vitreous Hyperreflective Foci in Optical Coherence Tomographic Scans of Patients With Diabetic Macular Edema

IMPORTANCE

Developing a noninvasive measure of diabetic retinopathy disease progression may provide physicians with information needed for patient-specific intervention.

OBJECTIVE

To develop an algorithm to measure vitreous hyperreflective foci (VHRF) from standard, 3-dimensional optical coherence tomographic (OCT) images in an unbiased manner.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively analyzed OCT scans from 97 patients who were evaluated at the Kellogg Eye Center, University of Michigan. Patients with diabetes mellitus without signs of retinopathy (n =  9) and patients with diabetic macular edema (DME) (n = 31) were compared with healthy control participants (n = 37). The algorithm was used to determine whether the VHRF score is associated with DME and may serve as a noninvasive measure of inflammation. The study was conducted from November 14, 2011, to August 5, 2015. Data analysis was performed from May 15, 2014, to August 13, 2015.

MAIN OUTCOMES AND MEASURES

An algorithm was developed to enhance the vitreous imaging from OCT to allow automated quantification of VHRF and calculation of a VHRF score. This score was compared between the healthy control, diabetes without retinopathy, and DME groups.

RESULTS

In the 97 scans evaluated, VHRF scores, reported as mean (SD), were increased in patients with DME by 2.95-fold (5.60 [8.65]) compared with healthy controls (1.90 [3.42]; 95% CI, 0.75-7.45; P = .012) and by 6.83-fold compared with patients with diabetes without retinopathy (0.82 [1.26]; 95% CI, 1.46-8.82; P = .005).

CONCLUSIONS AND RELEVANCE

Scores obtained using the VHRF algorithm may be obtained from OCT images that include the vitreous and could provide a rapid, noninvasive clinical correlate for ocular inflammation. Higher VHRF scores in patients with DME compared with controls and diabetic patients without retinopathy warrant further population-based and longitudinal studies to help determine the value of the VHRF score in selecting therapeutic intervention.

Antimyeloperoxidase antibody is a biomarker for progression of diabetic retinopathy

AIM

To study the correlation between serum antimyeloperoxidase (MPO) antibody levels with severity of diabetic retinopathy (DR).

METHODS

Study subjects included 60 consecutive cases of type 2 diabetes mellitus (DM): no diabetic retinopathy (NODR, n=20); nonproliferative DR (NPDR, n=20); proliferative DR (PDR, n=20) and 20 healthy controls. Best corrected visual acuity (BCVA) was measured on logMAR scale. Serum anti-MPO antibody levels were evaluated using ELISA IgG kit. Serum urea and creatinine was measured using standard protocol. Data were analysed statistically.

RESULTS

Mean serum anti-MPO antibody (RU/ml) was 16.94 ± 4.85 in controls, 17.66 ± 4.78 in NODR, 21.51 ± 5.27 in NPDR and 37.27 ± 11.92 in PDR groups. On ANOVA, significant difference in visual acuity was found among the study groups (F=73.46, p<0.001). Serum anti-MPO antibody was correlated significantly with decrease in visual acuity (F=48.40, p<0.001), increase in serum urea (F=128.13, p<0.001) and creatinine (F=77.10, p<0.001).

CONCLUSION

Increase in serum anti-MPO antibody levels correlate with increased severity of DR. Serum anti-MPO antibody may be a noteworthy biochemical marker for progression of retinopathy from nonproliferative to proliferative stage.

Nur77-deficiency in bone marrow-derived macrophages modulates inflammatory responses, extracellular matrix homeostasis, phagocytosis and tolerance

Background

The nuclear orphan receptor Nur77 (NR4A1, TR3, or NGFI-B) has been shown to modulate the inflammatory response of macrophages. To further elucidate the role of Nur77 in macrophage physiology, we compared the transcriptome of bone marrow-derived macrophages (BMM) from wild-type (WT) and Nur77-knockout (KO) mice.

Results

In line with previous observations, SDF-1α (CXCL12) was among the most upregulated genes in Nur77-deficient BMM and we demonstrated that Nur77 binds directly to the SDF-1α promoter, resulting in inhibition of SDF-1α expression. The cytokine receptor CX3CR1 was strongly downregulated in Nur77-KO BMM, implying involvement of Nur77 in macrophage tolerance. Ingenuity pathway analyses (IPA) to identify canonical pathways regulation and gene set enrichment analyses (GSEA) revealed a potential role for Nur77 in extracellular matrix homeostasis. Nur77-deficiency increased the collagen content of macrophage extracellular matrix through enhanced expression of several collagen subtypes and diminished matrix metalloproteinase (MMP)-9 activity. IPA upstream regulator analyses discerned the small GTPase Rac1 as a novel regulator of Nur77-mediated gene expression. We identified an inhibitory feedback loop with increased Rac1 activity in Nur77-KO BMM, which may explain the augmented phagocytic activity of these cells. Finally, we predict multiple chronic inflammatory diseases to be influenced by macrophage Nur77 expression. GSEA and IPA associated Nur77 to osteoarthritis, chronic obstructive pulmonary disease, rheumatoid arthritis, psoriasis, and allergic airway inflammatory diseases.

Conclusions

Altogether these data identify Nur77 as a modulator of macrophage function and an interesting target to treat chronic inflammatory disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2469-9) contains supplementary material, which is available to authorized users.

Elevated Levels of Cytokines Associated with Th2 and Th17 Cells in Vitreous Fluid of Proliferative Diabetic Retinopathy Patients

Macrophages are involved in low-grade inflammation in diabetes, and play pathogenic roles in proliferative diabetic retinopathy (PDR) by producing proinflammatory cytokines. T cells as well as other cells are also activated by proinflammatory cytokines, and infiltration into the vitreous of patients with PDR has been shown. In this study, we measured helper T (Th) cell-related cytokines in the vitreous of PDR patients to define the characteristics of Th-mediated immune responses associated with PDR. The study group consisted of 25 type 2 diabetic patients (25 eyes) with PDR. The control group consisted of 27 patients with epiretinal membrane (ERM), 26 patients with idiopathic macular hole (MH), and 26 patients with uveitis associated with sarcoidosis. Vitreous fluid was obtained at the beginning of vitrectomy, and centrifuging for cellular removals was not performed. Serum was also collected from PDR patients. IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, IFN-γ, soluble sCD40L, and TNFα in the vitreous and serum samples were measured. Both percent detectable and levels of IL-4, IL-6, IL-17A, IL-21, IL-22, and TNFα in the vitreous were significantly higher than those in the serum in PDR patients. Vitreous levels of these cytokines and IL-31 were significantly higher in PDR than in ERM or MH patients. Vitreous levels of IL-4, IL-17A, IL-22, IL-31, and TNFα in PDR patients were also significantly higher than those of sarcoidosis patients. In PDR patients, vitreous IL-17A level correlated significantly with vitreous levels of IL-22 and IL-31, and especially with IL-4 and TNFα. Although it is unclear whether these cytokines play facilitative roles or inhibitory roles for the progression of PDR, the present study indicated that Th2- and Th17-related immune responses are involved in the pathogenesis of PDR.

Expression of bioactive lysophospholipids and processing enzymes in the vitreous from patients with proliferative diabetic retinopathy

Background

The bioactive lysophospholipids phosphatidic acid (PA), lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) have been implicated in mediating cell migration, proliferation and apoptosis, inflammation, angiogenesis and fibrosis. This study was conducted to measure the levels of PA, LPA, LPA-producing enzymes phospholipase A1/A2 (PLA1A/PLA2, respectively) and acylgylycerol kinase (AGK), the S1P receptor S1PR1, the S1P catabolising enzyme S1P lyase (SPL) and 5-lipoxygenase in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR). In addition, we investigated the correlations between the levels of PA and LPA and the levels of the inflammatory and endothelial dysfunction biomarker soluble vascular cell adhesion molecule-1 (sVCAM-1).

Methods

Vitreous samples from 34 PDR and 29 nondiabetic patients were studied by biochemical and enzyme-linked immunosorbent assays and Western blot analysis.

Results

PA, LPA and sVCAM-1 levels in vitreous samples from PDR patients were significantly higher than those in nondiabetic patients. Significant correlations were observed between levels of LPA and levels of PA and sVCAM-1. Western blot analysis revealed a significant increase in the expression of PLA1A, AGK, S1PR1 and SPL in vitreous samples from PDR patients compared to nondiabetic controls, whereas PLA2 and 5-lipoxygenase were not detected.

Conclusions

Our findings suggest that the enzymatic activities of PLA1A and AGK might be responsible for increased synthesis of LPA in PDR and that PLA1A, but not PLA2 is responsible for deacylation of PA to generate LPA. S1PR1 and SPL might regulate inflammatory, angiogenic and fibrogenic responses in PDR.