Natural carboxyterminal truncation of human CXCL10 attenuates glycosaminoglycan binding, CXCR3A signaling and lymphocyte chemotaxis, while retaining angiostatic activity.

BACKGROUND: Interferon-γ-inducible protein of 10 kDa (IP-10/CXCL10) is a dual-function CXC chemokine that coordinates chemotaxis of activated T cells and natural killer (NK) cells via interaction with its G protein-coupled receptor (GPCR), CXC chemokine receptor 3 (CXCR3). As a consequence of natural posttranslational modifications, human CXCL10 exhibits a high degree of structural and functional heterogeneity. However, the biological effect of natural posttranslational processing of CXCL10 at the carboxy (C)-terminus has remained partially elusive. We studied CXCL10(1-73), lacking the four endmost C-terminal amino acids, which was previously identified in supernatant of cultured human fibroblasts and keratinocytes. METHODS: Relative levels of CXCL10(1-73) and intact CXCL10(1-77) were determined in synovial fluids of patients with rheumatoid arthritis (RA) through tandem mass spectrometry. The production of CXCL10(1-73) was optimized through Fmoc-based solid phase peptide synthesis (SPPS) and a strategy to efficiently generate human CXCL10 proteoforms was introduced. CXCL10(1-73) was compared to intact CXCL10(1-77) using surface plasmon resonance for glycosaminoglycan (GAG) binding affinity, assays for cell migration, second messenger signaling downstream of CXCR3, and flow cytometry of CHO cells and primary human T lymphocytes and endothelial cells. Leukocyte recruitment in vivo upon intraperitoneal injection of CXCL10(1-73) was also evaluated. RESULTS: Natural CXCL10(1-73) was more abundantly present compared to intact CXCL10(1-77) in synovial fluids of patients with RA. CXCL10(1-73) had diminished affinity for GAG including heparin, heparan sulfate and chondroitin sulfate A. Moreover, CXCL10(1-73) exhibited an attenuated capacity to induce CXCR3A-mediated signaling, as evidenced in calcium mobilization assays and through quantification of phosphorylated extracellular signal-regulated kinase-1/2 (ERK1/2) and protein kinase B/Akt. Furthermore, CXCL10(1-73) incited significantly less primary human T lymphocyte chemotaxis in vitro and peritoneal ingress of CXCR3+ T lymphocytes in mice. In contrast, loss of the four endmost C-terminal residues did not affect the inhibitory properties of CXCL10 on migration, proliferation, wound closure, phosphorylation of ERK1/2, and sprouting of human microvascular endothelial cells. CONCLUSION: Our study shows that the C-terminal residues Lys74-Pro77 of CXCL10 are important for GAG binding, signaling through CXCR3A, T lymphocyte chemotaxis, but dispensable for angiostasis.

Sputum from patients with primary ciliary dyskinesia contains high numbers of dysfunctional neutrophils and inhibits efferocytosis.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a genetic disorder characterized by recurrent airway infection and inflammation. There is no cure for PCD and to date there are no specific treatments available. Neutrophils are a crucial part of the immune system and are known to be dysfunctional in many inflammatory diseases. So far, the role of the neutrophils in PCD airways is largely unknown. The purpose of this study was to investigate the phenotype and function of airway neutrophils in PCD, and compare them to blood neutrophils. METHODS: Paired peripheral blood and spontaneously expectorated sputum samples from patients with PCD (n = 32) and a control group of patients with non-PCD, non-cystic fibrosis bronchiectasis (n = 5) were collected. The expression of neutrophil-specific surface receptors was determined by flow cytometry. Neutrophil function was assessed by measuring the extent of actin polymerization, production of reactive oxygen species (ROS) and release of neutrophil extracellular traps (NETs) in response to activating stimuli. RESULTS: Sputum neutrophils displayed a highly activated phenotype and were unresponsive to stimuli that would normally induce ROS production, actin polymerization and the expulsion of NETs. In addition, PCD sputum displayed high activity of neutrophil elastase, and impaired the efferocytosis by healthy donor macrophages. CONCLUSIONS: Sputum neutrophils in PCD are dysfunctional and likely contribute to ongoing inflammation in PCD airways. Further research should focus on anti-inflammatory therapies and stimulation of efferocytosis as a strategy to treat PCD.

Absence of CCR2 Promotes Proliferation of Alveolar Macrophages That Control Lung Inflammation in Acute Respiratory Distress Syndrome in Mice.

Acute respiratory distress syndrome (ARDS) consists of uncontrolled inflammation that causes hypoxemia and reduced lung compliance. Since it is a complex process, not all details have been elucidated yet. In a well-controlled experimental murine model of lipopolysaccharide (LPS)-induced ARDS, the activity and viability of macrophages and neutrophils dictate the beginning and end phases of lung inflammation. C-C chemokine receptor type 2 (CCR2) is a critical chemokine receptor that mediates monocyte/macrophage activation and recruitment to the tissues. Here, we used CCR2-deficient mice to explore mechanisms that control lung inflammation in LPS-induced ARDS. CCR2-/- mice presented higher total numbers of pulmonary leukocytes at the peak of inflammation as compared to CCR2+/+ mice, mainly by enhanced influx of neutrophils, whereas we observed two to six-fold lower monocyte or interstitial macrophage numbers in the CCR2-/-. Nevertheless, the time needed to control the inflammation was comparable between CCR2+/+ and CCR2-/-. Interestingly, CCR2-/- mice presented higher numbers and increased proliferative rates of alveolar macrophages from day 3, with a more pronounced M2 profile, associated with transforming growth factor (TGF)-ß and C-C chemokine ligand (CCL)22 production, decreased inducible nitric oxide synthase (Nos2), interleukin (IL)-1ß and IL-12b mRNA expression and increased mannose receptor type 1 (Mrc1) mRNA and CD206 protein expression. Depletion of alveolar macrophages significantly delayed recovery from the inflammatory insult. Thus, our work shows that the lower number of infiltrating monocytes in CCR2-/- is partially compensated by increased proliferation of resident alveolar macrophages during the inflammation control of experimental ARDS.

Role for Granulocyte Colony-Stimulating Factor in Neutrophilic Extramedullary Myelopoiesis in a Murine Model of Systemic Juvenile Idiopathic Arthritis.

OBJECTIVE: Systemic juvenile idiopathic arthritis (JIA) is a systemic inflammatory disease with childhood onset. Systemic JIA is associated with neutrophilia, including immature granulocytes, potentially driven by the growth factor granulocyte-colony stimulating factor (G-CSF). This study was undertaken to investigate the role of G-CSF in the pathology of systemic JIA. METHODS: Injection of Freund's complete adjuvant (CFA) in BALB/c mice induces mild inflammation and neutrophilia in wild-type (WT) mice and a more pronounced disease, reminiscent to that of JIA patients, in interferon-γ-knockout (IFNγ-KO) mice. Extramedullary myelopoiesis was studied in CFA-immunized mice by single-cell RNA sequencing, and the effect of G-CSF receptor (G-CSFR) blockage on neutrophil development and systemic JIA pathology was evaluated. Additionally, plasma G-CSF levels were measured in patients. RESULTS: Both in systemic JIA patients and in a corresponding mouse model, plasma G-CSF levels were increased. In the mouse model, we demonstrated that G-CSF is responsible for the observed neutrophilia and extramedullary myelopoiesis and the induction of immature neutrophils and myeloid-derived suppressor-like cells. Administration of a G-CSFR antagonizing antibody blocked the maturation and differentiation of neutrophils in CFA-immunized mice. In IFNγ-KO mice, treatment was associated with almost complete inhibition of arthritis due to reduced neutrophilia and osteoclast formation. Disease symptoms were ameliorated, but slight increases in interleukin-6 (IL-6), tumor necrosis factor, and IL-17 were detected upon G-CSFR inhibition in the IFNγ-KO mice, and were associated with mild increases in weight loss, tail damage, and immature red blood cells. CONCLUSION: We describe the role of G-CSF in a mouse model of systemic JIA and suggest an important role for G-CSF-induced myelopoiesis and neutrophilia in regulating the development of arthritis.

Inhibition of renal fibrosis with a human CXCL9-derived glycosaminoglycan-binding peptide.

OBJECTIVES: Renal fibrosis accompanies all chronic kidney disorders, ultimately leading to end-stage kidney disease and the need for dialysis or even renal replacement. As such, renal fibrosis poses a major threat to global health and the search for effective therapeutic strategies to prevent or treat fibrosis is highly needed. We evaluated the applicability of a highly positively charged human peptide derived from the COOH-terminal domain of the chemokine CXCL9, namely CXCL9(74-103), for therapeutic intervention. Because of its high density of net positive charges at physiological pH, CXCL9(74-103) competes with full-length chemokines for glycosaminoglycan (GAG) binding. Consequently, CXCL9(74-103) prevents recruitment of inflammatory leucocytes to sites of inflammation. METHODS: CXCL9(74-103) was chemically synthesised and tested in vitro for anti-fibrotic properties on human fibroblasts and in vivo in the unilateral ureteral obstruction (UUO) mouse model. RESULTS: CXCL9(74-103) significantly reduced the mRNA and/or protein expression of connective tissue growth factor (CTGF), alpha-smooth muscle actin (α-SMA) and collagen III by transforming growth factor (TGF)-ß1-stimulated human fibroblasts. In addition, administration of CXCL9(74-103) inhibited fibroblast migration towards platelet-derived growth factor (PDGF), without affecting cell viability. In the UUO model, CXCL9(74-103) treatment significantly decreased renal α-SMA, vimentin, and fibronectin mRNA and protein expression. Compared with vehicle, CXCL9(74-103) attenuated mRNA expression of TGF-ß1 and the inflammatory markers/mediators MMP-9, F4/80, CCL2, IL-6 and TNF-α. Finally, CXCL9(74-103) treatment resulted in reduced influx of leucocytes in the UUO model and preserved tubular morphology. The anti-fibrotic and anti-inflammatory effects of CXCL9(74-103) were mediated by competition with chemokines and growth factors for GAG binding. CONCLUSIONS: Our findings provide a scientific rationale for targeting GAG-protein interactions in renal fibrotic disease.

Proteoform Analysis of Matrix Metalloproteinase-9/Gelatinase B and Discovery of Its Citrullination in Rheumatoid Arthritis Synovial Fluids.

Objectives: To explore posttranslational modifications (PTMs), including proteolytic activation, multimerization, complex formation and citrullination of gelatinases, in particular of gelatinase B/MMP-9, and to detect in gelatin-Sepharose affinity-purified synovial fluids, the presence of specific MMP proteoforms in relation to arthritis. Methods: Latent, activated, complexed and truncated gelatinase-A/MMP-2 and gelatinase B/MMP-9 proteoforms were detected with the use of zymography analysis to compare specific levels, with substrate conversion assays, to test net proteolytic activities and by Western blot analysis to decipher truncation variants. Citrullination was detected with enhanced sensitivity, by the use of a new monoclonal antibody against modified citrullines. Results: All MMP-9 and MMP-2 proteoforms were identified in archival synovial fluids with the use of zymography analysis and the levels of MMP-9 versus MMP-2 were studied in various arthritic diseases, including rheumatoid arthritis (RA). Secondly, we resolved misinterpretations of MMP-9 levels versus proteolytic activities. Thirdly, a citrullinated, truncated proteoform of MMP-9 was discovered in archival RA synovial fluid samples and its presence was corroborated as citrullinated hemopexin-less MMP-9 in a small prospective RA sample cohort. Conclusion: Synovial fluids from rheumatoid arthritis contain high levels of MMP-9, including its truncated and citrullinated proteoform. The combination of MMP-9 as analyte and its PTM by citrullination could be of clinical interest, especially in the field of arthritic diseases.

The Chemokine-Based Peptide, CXCL9(74-103), Inhibits Angiogenesis by Blocking Heparan Sulfate Proteoglycan-Mediated Signaling of Multiple Endothelial Growth Factors.

Growth factors such as vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and epidermal growth factor (EGF) are important angiogenesis-mediating factors. They exert their effects not only through their respective receptor tyrosine kinases (RTKs), but they also require molecular pairing with heparan sulfate proteoglycans (HSPGs). Angiogenic growth factors and their signaling pathways are commonly targeted in current anti-angiogenic cancer therapies but have unfortunately insufficient impact on patient survival. Considering their obvious role in pathological angiogenesis, HS-targeting drugs have become an appealing new strategy. Therefore, we aimed to reduce angiogenesis through interference with growth factor-HS binding and downstream signaling using a CXCL9-derived peptide with a high affinity for glycosaminoglycans (GAGs), CXCL9(74-103). We showed that CXCL9(74-103) reduced EGF-, VEGF165- and FGF-2-mediated angiogenic processes in vitro, such as endothelial cell proliferation, chemotaxis, adhesion and sprouting, without exerting cell toxicity. CXCL9(74-103) interfered with growth factor signaling in diverse ways, e.g., by diminishing VEGF165 binding to HS and by direct association with FGF-2. The dependency of CXCL9(74-103) on HS for binding to HMVECs and for exerting its anti-angiogenic activity was also demonstrated. In vivo, CXCL9(74-103) attenuated neovascularization in the Matrigel plug assay, the corneal cauterization assay and in MDA-MB-231 breast cancer xenografts. Additionally, CXCL9(74-103) reduced vascular leakage in the retina of diabetic rats. In contrast, CXCL9(86-103), a peptide with low GAG affinity, showed no overall anti-angiogenic activity. Altogether, our results indicate that CXCL9(74-103) reduces angiogenesis by interfering with multiple HS-dependent growth factor signaling pathways.

Endogenous modification of the chemoattractant CXCL5 alters receptor usage and enhances its activity toward neutrophils and monocytes.

The inflammatory human chemokine CXCL5 interacts with the G protein-coupled receptor CXCR2 to induce chemotaxis and activation of neutrophils. CXCL5 also has weak agonist activity toward CXCR1. The N-terminus of CXCL5 can be modified by proteolytic cleavage or deimination of Arg9 to citrulline (Cit), and these modifications can occur separately or together. Here, we chemically synthesized native CXCL5(1-78), truncated CXCL5 [CXCL5(9-78)], and the citrullinated (Cit9) versions and characterized their functions in vitro and in vivo. Compared with full-length CXCL5, N-terminal truncation resulted in enhanced potency to induce G protein signaling and ß-arrestin recruitment through CXCR2, increased CXCL5-initiated internalization of CXCR2, and greater Ca2+ signaling downstream of not only CXCR2 but also CXCR1. Citrullination did not affect the capacity of CXCL5 to activate classical or alternative signaling pathways. Administering the various CXCL5 forms to mice revealed that in addition to neutrophils, CXCL5 exerted chemotactic activity toward monocytes and that this activity was increased by N-terminal truncation. These findings were confirmed by in vitro chemotaxis and Ca2+ signaling assays with primary human CD14+ monocytes and human THP-1 monocytes. In vitro and in vivo analyses suggested that CXCL5 targeted monocytes through CXCR1 and CXCR2. Thus, truncation of the N-terminus makes CXCL5 a more potent chemoattractant for both neutrophils and monocytes that acts through CXCR1 and CXCR2.

Biological Characterization of Commercial Recombinantly Expressed Immunomodulating Proteins Contaminated with Bacterial Products in the Year 2020: The SAA3 Case.

The serum amyloid A (SAA) gene family is highly conserved and encodes acute phase proteins that are upregulated in response to inflammatory triggers. Over the years, a considerable amount of literature has been published attributing a wide range of biological effects to SAAs such as leukocyte recruitment, cytokine and chemokine expression and induction of matrix metalloproteinases. Furthermore, SAAs have also been linked to protumorigenic, proatherogenic and anti-inflammatory effects. Here, we investigated the biological effects conveyed by murine SAA3 (mu rSAA3) recombinantly expressed in Escherichia coli. We observed the upregulation of a number of chemokines including CCL2, CCL3, CXCL1, CXCL2, CXCL6 or CXCL8 following stimulation of monocytic, fibroblastoid and peritoneal cells with mu rSAA3. Furthermore, this SAA variant displayed potent in vivo recruitment of neutrophils through the activation of TLR4. However, a major problem associated with proteins derived from recombinant expression in bacteria is potential contamination with various bacterial products, such as lipopolysaccharide, lipoproteins and formylated peptides. This is of particular relevance in the case of SAA as there currently exists a discrepancy in biological activity between SAA derived from recombinant expression and that of an endogenous source, i.e. inflammatory plasma. Therefore, we subjected commercial recombinant mu rSAA3 to purification to homogeneity via reversed-phase high-performance liquid chromatography (RP-HPLC) and re-assessed its biological potential. RP-HPLC-purified mu rSAA3 did not induce chemokines and lacked in vivo neutrophil chemotactic activity, but retained the capacity to synergize with CXCL8 in the activation of neutrophils. In conclusion, experimental results obtained when using proteins recombinantly expressed in bacteria should always be interpreted with care.

Serum Amyloid A1 (SAA1) Revisited: Restricted Leukocyte-Activating Properties of Homogeneous SAA1.

Infection, sterile injury, and chronic inflammation trigger the acute phase response in order to re-establish homeostasis. This response includes production of positive acute phase proteins in the liver, such as members of the serum amyloid A (SAA) family. In humans the major acute phase SAAs comprise a group of closely related variants of SAA1 and SAA2. SAA1 was proven to be chemotactic for several leukocyte subtypes through activation of the G protein-coupled receptor FPRL1/FPR2. Several other biological activities of SAA1, such as cytokine induction, reported to be mediated via TLRs, have been debated recently. Especially commercial SAA1, recombinantly produced in Escherichia coli, was found to be contaminated with bacterial products confounding biological assays performed with this rSAA1. We purified rSAA1 by RP-HPLC to homogeneity, removing contaminants such as lipopolysaccharides, lipoproteins and formylated peptides, and re-assessed several biological activities attributed to SAA1 (chemotaxis, cytokine induction, MMP-9 release, ROS generation, and macrophage differentiation). The homogeneous rSAA1 (hrSAA1) lacked most cell-activating properties, but its leukocyte-recruiting capacity in vivo and it's in vitro synergy with other leukocyte attractants remained preserved. Furthermore, hrSAA1 maintained the ability to promote monocyte survival. This indicates that pure hrSAA1 retains its potential to activate FPR2, whereas TLR-mediated effects seem to be related to traces of bacterial TLR ligands in the E. coli-produced human rSAA1.

Truncation of CXCL8 to CXCL8(9-77) enhances actin polymerization and in vivo migration of neutrophils.

CXCL8 is the principal human neutrophil-attracting chemokine and a major mediator of inflammation. The chemokine exerts its neutrophil-chemotactic and neutrophil-activating activities via interaction with glycosaminoglycans (GAGs) and activation of the G protein-coupled receptors (GPCRs) CXCR1 and CXCR2. Natural CXCL8 displays an exceptional degree of amino (NH2 )-terminal heterogeneity. Most CXCL8 forms result from proteolytic processing of authentic CXCL8(1-77). Here, we compared the potencies to activate and recruit neutrophils of the 3 most abundant natural CXCL8 forms: full-length 77 amino acid CXCL8 and the 2 major natural truncated forms lacking 5 or 8 NH2 -terminal amino acids. NH2 -terminal truncation hardly affected the capacity of CXCL8 to induce shedding of CD62L or to up-regulate the expression of the adhesion molecules CD11a, CD11b, or CD15 on human neutrophils. In addition, the potency of CXCL8 to induce neutrophil degranulation and its effect on phagocytosis remained unaltered upon removal of 5 or 8 NH2 -terminal residues. However, NH2 -terminal truncation strongly potentiated CXCL8-induced actin polymerization. CXCL8(6-77) and CXCL8(9-77) showed a comparable capacity to induce Ca2+ signaling in human neutrophils and to direct in vitro neutrophil migration. Strikingly, the ability of CXCL8(9-77) to recruit neutrophils into the peritoneal cavity of mice was significantly enhanced compared to CXCL8(6-77). These results suggest that NH2 -terminal truncation influences specific biological activities of CXCL8 and indicate that CXCL8(9-77) may be the most potent neutrophil-attracting CXCL8 form in vivo.

Induction of Chemokines by Hepatitis C Virus Proteins: Synergy of the Core Protein with Interleukin-1ß and Interferon-γ in Liver Bystander Cells.

Chronic hepatitis C virus (HCV) infection accounts for a large proportion of hepatic fibrosis and carcinoma cases observed worldwide. Mechanisms involved in HCV-induced hepatic injury have yet to be fully elucidated. Of particular interest is the capacity of HCV to regulate inflammatory responses. Here, we reveal modulation of cytokine activity by the HCV proteins non-structural protein 3 (NS3), glycoprotein E2, and core protein for their ability to induce chemokine expression in various liver bystander cells. Chemokines sustain chronic liver inflammation and relay multiple fibrogenic effects. CCL2, CCL3, CCL20, CXCL8, and CXCL10 were differentially expressed after treatment of monocytes, fibroblasts, or liver sinusoidal microvascular endothelial cells (LSECs) with HCV proteins. In comparison to NS3 and glycoprotein E2, core protein was a stronger inducer of chemokines in liver bystander cells. Interferon-γ (IFN-γ) and interleukin-1ß (IL-1ß) synergized with core protein to induce CCL2, CCL20, CXCL8, or CXCL10 in fibroblasts or LSECs. These findings reveal new mechanisms of hepatic injury caused by HCV.

Local Cytokine Expression Profiling in Patients with Specific Autoimmune Uveitic Entities.

Purpose: To evaluate expression of cytokines GM-CSF, IL-11, IL-12p40, IL-12p70, IL-27p28, IL-35, APRIL, BAFF, TWEAK, and LIGHT in uveitis.Methods: Aqueous humor samples from patients with active uveitis associated with Behçet's disease (BD), sarcoidosis, HLA-B27-related inflammation, and Vogt-Koyanagi-Harada (VKH) disease and control patients were assayed with a multiplex assay.Results: Comparing all patients to controls, GM-CSF, IL-11, IL-12p40, APRIL, and BAFF were significantly increased, whereas LIGHT was significantly decreased. IL-11 and BAFF were the most strongly upregulated, being elevated 19.7-fold and 14.1-fold, respectively, compared with controls. IL-11 was significantly highest in HLA-B27 uveitis. GM-CSF, IL-11, and IL-12p40 were significantly higher in nongranulomatous uveitis (BD and HLA-B27) than in granulomatous uveitis (sarcoidosis and VKH), whereas APRIL and TWEAK were significantly higher in granulomatous uveitis.Conclusions: IL-11-driven immune responses might be more potent in nongranulomatous uveitis, particularly in HLA-B27 uveitis. BAFF and APRIL might contribute to B cell-driven autoimmune response in uveitis.

Soluble cytokine receptor levels in aqueous humour of patients with specific autoimmune uveitic entities: sCD30 is a biomarker of granulomatous uveitis.

PURPOSE: Soluble cytokine receptors are potential biomarkers for immune activation and have a promising potential as immunotherapeutic agents. We investigated the levels of soluble cytokine receptors in aqueous humour (AH) samples from patients with specific autoimmune uveitic entities. METHODS: Patients with active uveitis associated with Behçet's disease (BD) (n = 13), sarcoidosis (n = 8), HLA-B27-related inflammation (n = 12), Vogt-Koyanagi-Harada (VKH) disease (n = 12) and control subjects (n = 9) were included. AH samples were analyzed with the use of multiplex assays for the proinflammatory cytokine tumour necrosis factor (TNF)-α and the soluble cytokine receptors sCD30, sCD163, sgp130, sIL-6 receptor-α (sIL-6R), sTNFRI and sTNFRII. RESULTS: TNF-α and soluble cytokine receptor AH levels were significantly higher in uveitis patients (n = 45) compared with controls (n = 9). When nongranulomatous uveitis (BD and HLA-B27-associated uveitis) was compared with granulomatous uveitis (sarcoidosis and VKH disease), the levels of sCD30 and sTNFRI/TNF-α and sTNFRII/TNF-α ratios were significantly enhanced in granulomatous uveitis. Finally, when comparing the profile in the specific uveitis entities, sCD30 levels were highest in patients with VKH disease. sgp130, sCD163, sIL-6R, sTNFRI and sTNFRII did not differ significantly between the four different clinical uveitic subgroups. CONCLUSIONS: Soluble cytokine receptors are significantly upregulated in autoimmune uveitis. CD30+ T cells might contribute to the inflammatory process in granulomatous uveitis, particularly in VKH disease. Granulomatous uveitis is also characterized by significantly higher sTNFRs/TNF-α ratios than nongranulomatous uveitis.

Expression of interleukin (IL)-10 family cytokines in aqueous humour of patients with specific endogenous uveitic entities: elevated levels of IL-19 in human leucocyte antigen-B27-associated uveitis.

PURPOSE: Evidence exists that the interleukin (IL)-10 family of cytokines is involved in autoimmune diseases. The aim of this study was to analyse the levels of the IL-10 family cytokines IL-10, IL-19, IL-20, IL-22, IL-26, IL-28A and IL-29 in aqueous humour (AH) samples from patients with specific uveitic entities. In addition, we correlated their levels with the levels of the proinflammatory cytokines tumour necrosis factor-α (TNF-α) and IL-1ß. METHODS: Aqueous humour (AH) samples from patients with active uveitis associated with Behçet's disease (BD; n = 13), sarcoidosis (n = 8), human leucocyte antigen (HLA)-B27-related inflammation (n = 12), Vogt-Koyanagi-Harada (VKH) disease (n = 12) and control subjects (n = 9) were assayed with the use of a multiplex assay. RESULTS: Of all the IL-10 family cytokines studied, only IL-19 levels were significantly higher in AH samples of patients (n = 45) than in controls (p = 0.022). When comparing the four individual disease groups to controls, IL-19 levels were only significantly higher in HLA-B27-associated uveitis (p < 0.001). IL-19 levels were significantly higher in patients with HLA-B27-associated uveitis than in patients with BD, sarcoidosis and VKH disease (p < 0.001; p = 0.002; p < 0.001, respectively). Significant correlations were found between AH levels of IL-19 and AH levels of TNF-α, (r = 0.3; p = 0.03) and IL-1ß (r = 0.56; p < 0.001). CONCLUSIONS: Among the IL-10 family cytokines analysed, IL-19 demonstrated the highest expression in endogenous uveitis, particularly in HLA-B27-associated uveitis. IL-19 thus might assist in the regulation of inflammation in HLA-B27-associated uveitis.

The CC chemokines CCL8, CCL13 and CCL20 are local inflammatory biomarkers of HLA-B27-associated uveitis.

PURPOSE: To determine the concentrations of the CC chemokines CCL2, CCL7, CCL8, CCL11, CCL13, CCL20, CCL24 and CCL26 in aqueous humour (AH) samples from patients with specific uveitic entities. METHODS: Aqueous humour samples from patients with active uveitis associated with Behçet's disease (BD) (n = 13), sarcoidosis (n = 8), HLA-B27-related inflammation (n = 12), Vogt-Koyanagi-Harada (VKH) disease (n = 12) and control patients (n = 9) were assayed with the use of a multiplex assay. RESULTS: When considering all uveitis patients as one group, all chemokine levels except CCL2 were significantly increased compared to controls. CCL8, CCL13 and CCL20 were the most strongly upregulated, 48-fold, 118-fold and 173-fold, respectively, above control AH levels. CCL8 and CCL13 levels were significantly higher in HLA-B27-associated uveitis than in sarcoidosis and VKH disease. CCL20 levels were significantly higher in HLA-B27-associated uveitis than in BD, sarcoidosis and VKH disease. In addition, CCL20 levels were significantly higher in BD than in VKH disease. In HLA-B27-associated uveitis, CCL8, CCL13 and CCL20 were upregulated 111-fold, 255-fold and 465-fold, respectively, compared with controls. CCL8, CCL13 and CCL20 levels were significantly higher in nongranulomatous uveitis (BD and HLA-B27-associated uveitis) than in granulomatous uveitis (sarcoidosis and VKH disease). CONCLUSION: Immune responses mediated by CCL8, CCL13 and CCL20 appear to be more potent in nongranulomatous uveitis, particularly in HLA-B27-associated uveitis.

Gelatinase B/matrix metalloproteinase-9 is a phase-specific effector molecule, independent from Fas, in experimental autoimmune encephalomyelitis.

Gelatinase B/matrix metalloproteinase-9 (MMP-9) triggers multiple sclerosis (MS) and the animal model of experimental autoimmune encephalomyelitis (EAE) by the breakdown of the blood-brain barrier. Interestingly, MMP-9 is beneficial in systemic autoimmunity caused by Fas-deficiency. Fas-deficient (faslpr) and Fas-ligand-deficient mice are protected against EAE. We here investigated the interaction between Fas and MMP-9 in the setting of induction of EAE and compared short- and long-term effects. We provoked EAE with myelin oligodendrocyte glycoprotein (MOG) peptide and compared EAE development in four genotypes (wild-type (WT), single knockout mmp-9-/-, faslpr, and mmp-9-/-/faslpr) and monitored leukocytes, cytokines and chemokines as immunological parameters. As expected, faslpr mice were resistant against EAE induction, whereas MMP-9 single knockout mice were not. In the double mmp-9-/-/ faslpr mice the effects on disease scores pointed to independent rather than interrelated disease mechanisms. On a short term, after EAE induction leukocytes infiltrated into the brain and cytokine and chemokine levels were significantly higher in all the four genotypes studied, even in the faslpr and mmp-9-/-/faslpr, which did not develop clinical disease. The levels of MMP-9 but not of MMP-2 were increased in the brain and in the peripheral organs after EAE induction. After 40 days all the animals recovered and did not show signs of EAE. However, the absence of MMP-9 in the remission phase suggested a protective role of MMP-9 in the late phase of the disease, because single mmp-9-/- mice presented a delayed remission in comparison with WT animals suggesting a phase-dependent role of MMP-9 in the disease. Nevertheless, the levels of some cytokines and chemokines remained higher than in control animals even 100 days after EAE induction, attesting to a prolonged state of immune activation. We thus yielded new insights and useful markers to monitor this activated immune status. Furthermore, MMP-9 but not MMP-2 levels remained increased in the brains and, to a higher extend, in the spleens of the WT mice even during the remission phase, which is in line with the role of MMP-9 as a useful marker and a protective factor for EAE in the remission phase.

Insufficient IL-10 Production as a Mechanism Underlying the Pathogenesis of Systemic Juvenile Idiopathic Arthritis.

Systemic juvenile idiopathic arthritis (sJIA) is a childhood-onset immune disorder of unknown cause. One of the concepts is that the disease results from an inappropriate control of immune responses to an initially harmless trigger. In the current study, we investigated whether sJIA may be caused by defects in IL-10, a key cytokine in controlling inflammation. We used a translational approach, with an sJIA-like mouse model and sJIA patient samples. The sJIA mouse model relies on injection of CFA in IFN-γ-deficient BALB/c mice; corresponding wild type (WT) mice only develop a subtle and transient inflammatory reaction. Diseased IFN-γ-deficient mice showed a defective IL-10 production in CD4+ regulatory T cells, CD19+ B cells, and CD3-CD122+CD49b+ NK cells, with B cells as the major source of IL-10. In addition, neutralization of IL-10 in WT mice resulted in a chronic immune inflammatory disorder clinically and hematologically reminiscent of sJIA. In sJIA patients, IL-10 plasma levels were strikingly low as compared with proinflammatory mediators. Furthermore, CD19+ B cells from sJIA patients showed a decreased IL-10 production, both ex vivo and after in vitro stimulation. In conclusion, IL-10 neutralization in CFA-challenged WT mice converts a transient inflammatory reaction into a chronic disease and represents an alternative model for sJIA in IFN-γ-competent mice. Cell-specific IL-10 defects were observed in sJIA mice and patients, together with an insufficient IL-10 production to counterbalance their proinflammatory cytokines. Our data indicate that a defective IL-10 production contributes to the pathogenesis of sJIA.

Anti-inflammatory effects of the GAG-binding CXCL9(74-103) peptide in dinitrofluorobenzene-induced contact hypersensitivity in mice.

BACKGROUND: To recruit leucocytes to an inflammatory site, chemokine binding to glycosaminoglycans (GAGs) is critical. Therefore, strategies to interfere with this interaction, aiming at the production of anti-inflammatory agents, were developed. These include production of modified chemokines without affinity for G protein-coupled receptors but with enhanced affinity for GAGs. Such modified chemokines compete with functional chemokines for GAG binding, prevent chemokine immobilization and presentation, and inhibit leucocyte migration. In addition to modified chemokines, a GAG-binding peptide consisting of the 30 COOH-terminal residues of CXCL9, that is CXCL9(74-103), inhibited CXCL8- and monosodium urate crystal-induced neutrophil migration. OBJECTIVE: We wanted to explore whether interference with chemokine-GAG interactions by CXCL9(74-103) reduces inflammation in neutrophil-dependent dinitrofluorobenzene-induced contact hypersensitivity. METHODS: For this study, we evaluated several inflammatory parameters, including ear swelling and the levels of chemokines, cytokines, proteases and neutrophils in the ears of dinitrofluorobenzene-induced mice treated with CXCL9(74-103) or buffer. RESULTS: One intravenous injection of CXCL9(74-103), just before painting with dinitrofluorobenzene on the ear, did not affect protein levels of the major murine neutrophil attractant, that is CXCL6, in this contact hypersensitivity model. However, IL-6, CXCL1, CCL2 and matrix metalloproteinase-9 (MMP-9) protein concentrations and peroxidase activity in challenged ears were reduced. In addition, intravenous injection of the CXCL9-derived peptide led to a reduced ear swelling response, indicating that the locally produced chemokines were hindered to attract leucocytes. The inhibiting potential of CXCL9(74-103) was explained by its competition for GAG binding with CXCL1, CXCL6 and CCL3 and inhibition of transendothelial migration of neutrophils to CXCL6. CONCLUSIONS AND CLINICAL RELEVANCE: The CXCL9(74-103) peptide inhibited dinitrofluorobenzene-induced infiltration of neutrophils and neutrophil-dependent inflammation in ears. Therefore, CXCL9(74-103) may be a lead molecule for the development of therapeutic peptides or peptide derivatives that compete with functional chemokines for GAG binding.