A multicenter blinded preclinical randomized controlled trial on Jak1/2 inhibition in MRL/MpJ-Faslpr mice with proliferative lupus nephritis predicts low effect size.

Data reproducibility and single-center bias are concerns in preclinical research and compromise translation from animal to human. Multicenter preclinical randomized controlled trials (pRCT) may reduce the gap between experimental studies and RCT and improve the predictability of results, for example Jak1/2 inhibition in lupus nephritis. To evaluate this, we conducted the first pRCT in the kidney domain at two Spanish and two German academic sites. Eligible MRL/MpJ-Faslpr mice (female, age13-14 weeks, stress scores of less than two and no visible tumor or signs of infection) were equally randomized to either oral treatment with the Jak1/2 inhibitor baricitinib or vehicle for four weeks. Central blinded histology analysis was performed at an independent fifth site. The primary endpoint was the urinary protein/creatinine ratio. Baricitinib treatment did not significantly affect proteinuria, histological markers of activity and chronicity, or the glomerular filtration rate but significantly improved plasma autoantibody levels and lymphadenopathy. Data heterogeneity was noted across the different centers referring in part to phenotype differences between MRL/MpJ-Faslpr mice bred at different sites, mimicking well patient phenotype diversity in lupus trials. Multicenter pRCT can overcome single-center bias at the cost of increasing variability and reducing effect size. Thus, our pRCT predicts a low effect size of baricitinib treatment on human lupus nephritis in heterogeneous study populations.

Neuraminidase Inhibitor Zanamivir Ameliorates Collagen-Induced Arthritis.

Altered sialylation patterns play a role in chronic autoimmune diseases such as rheumatoid arthritis (RA). Recent studies have shown the pro-inflammatory activities of immunoglobulins (Igs) with desialylated sugar moieties. The role of neuraminidases (NEUs), enzymes which are responsible for the cleavage of terminal sialic acids (SA) from sialoglycoconjugates, is not fully understood in RA. We investigated the impact of zanamivir, an inhibitor of the influenza virus neuraminidase, and mammalian NEU2/3 on clinical outcomes in experimental arthritides studies. The severity of arthritis was monitored and IgG titers were measured by ELISA. (2,6)-linked SA was determined on IgG by ELISA and on cell surfaces by flow cytometry. Zanamivir at a dose of 100 mg/kg (zana-100) significantly ameliorated collagen-induced arthritis (CIA), whereas zana-100 was ineffective in serum transfer-induced arthritis. Systemic zana-100 treatment reduced the number of splenic CD138+/TACI+ plasma cells and CD19+ B cells, which was associated with lower IgG levels and an increased sialylation status of IgG compared to controls. Our data reveal the contribution of NEU2/3 in CIA. Zanamivir down-modulated the T and B cell-dependent humoral immune response and induced an anti-inflammatory milieu by inhibiting sialic acid degradation. We suggest that neuraminidases might represent a promising therapeutic target for RA and possibly also for other antibody-mediated autoimmune diseases.

Relevance of Receptor for Advanced Glycation end Products (RAGE) in Murine Antibody-Mediated Autoimmune Diseases.

It is incompletely understood how self-antigens become targets of humoral immunity in antibody-mediated autoimmune diseases. In this context, alarmins are discussed as an important level of regulation. Alarmins are recognized by various receptors, such as receptor for advanced glycation end products (RAGE). As RAGE is upregulated under inflammatory conditions, strongly binds nucleic acids and mediates pro-inflammatory responses upon alarmin recognition, our aim was to examine its contribution to immune complex-mediated autoimmune diseases. This question was addressed employing RAGE-/- animals in murine models of pristane-induced lupus, collagen-induced, and serum-transfer arthritis. Autoantibodies were assessed by enzyme-linked immunosorbent assay, renal disease by quantification of proteinuria and histology, arthritis by scoring joint inflammation. The associated immune status was determined by flow cytometry. In both disease entities, we detected tendentiously decreased autoantibody levels in RAGE-/- mice, however no differences in clinical outcome. In accordance with autoantibody levels, a subgroup of the RAGE-/- animals showed a decrease in plasma cells, and germinal center B cells and an increase in follicular B cells. Based on our results, we suggest that RAGE deficiency alone does not significantly affect antibody-mediated autoimmunity. RAGE may rather exert its effects along with other receptors linking environmental factors to auto-reactive immune responses.

The sneaking ligand approach for cell type-specific modulation of intracellular signalling pathways.

Small molecules interfering with intracellular signalling pathways are used in the treatment of multiple diseases including RA. However, small molecules usually affect signalling in most cell types, not only in those which need to be targeted. This general inhibition of signalling pathways causes often adverse effects, which could be avoided by cell type-specific inhibitors. For cell-type specific modulation of signal transduction, we developed the sneaking ligand fusion proteins (SLFPs). SLFPs contain three domains: (1) the binding domain mediating cell type-specific targeting and endocytosis; (2) the endosomal release sequence releasing the effector domain into the cytoplasm; (3) the effector domain modulating signalling. Using our SLFP NF-kappaB inhibitor termed SLC1 we demonstrated that cell-type-specific modulation of intracellular signalling pathways is feasible, that endothelial NF-kappaB activation is critical for arthritis and peritonitis and that SLFPs help to identify disease-relevant pathways in defined cell types. Hence, SLFPs may improve risk-benefit ratios of therapeutic interventions.

Rsk2 controls synovial fibroblast hyperplasia and the course of arthritis.

OBJECTIVE: Arthritis is a chronic inflammatory disease characterised by immune cell infiltration and mesenchymal cell expansion in the joints. Although the role of immune cells in arthritis is well characterised, the development of mesenchymal cell hyperplasia needs to be better defined. Here, we analysed the role of the ribosomal S6 kinase Rsk2, which we found to be highly activated in joints of patients with arthritis, in the development of mesenchymal cell hyperplasia. METHODS: We genetically inactivated Rsk2 in the tumour necrosis factor (TNF)-α transgenic (TNFtg) mice, an animal model for human inflammatory arthritis. Clinical and histological signs of arthritis as well as molecular markers of inflammation and joint destruction were quantified. Fibroblast-like synoviocytes (FLS) were characterised in vitro and the effect of Rsk2 deletion on the pattern of gene expression was determined. RESULTS: Rsk2 deficiency in TNFtg mice results in earlier and exacerbated inflammation as well as increased bone and cartilage destruction. The production of inflammatory cytokines, matrix metalloproteinases and osteoclastogenic molecules was significantly increased in vivo upon Rsk2 inactivation. Bone marrow deficient in Rsk2 could not transfer this phenotype, indicating that Rsk2 expression in mesenchymal cells controls the course of arthritis. Indeed, Rsk2 deficiency was associated with a more activated phenotype and higher proliferative capacity of FLS, thereby increasing cytokines and production of matrix proteinases. CONCLUSIONS: Rsk2 emerges as a key regulator of mesenchymal cell numbers in the joint and thereby could be targeted to control the inflammatory and tissue-destructive feature of joints in arthritis.

NF-κB inhibitor targeted to activated endothelium demonstrates a critical role of endothelial NF-κB in immune-mediated diseases.

Activation of the nuclear transcription factor κB (NF-κB) regulates the expression of inflammatory genes crucially involved in the pathogenesis of inflammatory diseases. NF-κB governs the expression of adhesion molecules that play a pivotal role in leukocyte-endothelium interactions. We uncovered the crucial role of NF-κB activation within endothelial cells in models of immune-mediated diseases using a "sneaking ligand construct" (SLC) selectively inhibiting NF-κB in the activated endothelium. The recombinant SLC1 consists of three modules: (i) an E-selectin targeting domain, (ii) a Pseudomonas exotoxin A translocation domain, and (iii) a NF-κB Essential Modifier-binding effector domain interfering with NF-κB activation. The E-selectin-specific SLC1 inhibited NF-κB by interfering with endothelial IκB kinase 2 activity in vitro and in vivo. In murine experimental peritonitis, the application of SLC1 drastically reduced the extravasation of inflammatory cells. Furthermore, SLC1 treatment significantly ameliorated the disease course in murine models of rheumatoid arthritis. Our data establish that endothelial NF-κB activation is critically involved in the pathogenesis of arthritis and can be selectively inhibited in a cell type- and activation stage-dependent manner by the SLC approach. Moreover, our strategy is applicable to delineating other pathogenic signaling pathways in a cell type-specific manner and enables selective targeting of distinct cell populations to improve effectiveness and risk-benefit ratios of therapeutic interventions.

Methylation-dependent activation of CDX1 through NF-κB: a link from inflammation to intestinal metaplasia in the human stomach.

The caudal homeobox factor 1 (CDX1) is an essential transcription factor for intestinal differentiation. Its aberrant expression in intestinal metaplasia of the upper gastrointestinal tract is a hallmark within the gastritis-metaplasia-carcinoma sequence. CDX1 expression is influenced by certain pathways, such as Wnt, Ras, or NF-κB signaling; however, these pathways alone cannot explain the transient expression of CDX1 in intestinal metaplasia or the molecular inactivation mechanism of its loss in cases of advanced gastric cancer. In this study, we investigated the epigenetic inactivation of CDX1 by promoter methylation, as well as the functional link of CDX1 promoter methylation to the inflammatory NF-κB signaling pathway. We identified methylation-dependent NF-κB binding to the CDX1 promoter and quantified it using competitive electrophoretic mobility shift assays and chromatin immunoprecipitation. A methylated CDX1 promoter was associated with closed chromatin structure, reduced NF-κB binding, and transcriptional silencing. Along the gastritis-metaplasia-carcinoma sequence, we observed a biphasic pattern of tumor necrosis factor-α (TNF-α) protein expression and an inverse biphasic pattern of CDX1 promoter methylation; both are highly consistent with CDX1 protein expression. The stages of hyper-, hypo-, and hyper-methylation patterns of the CDX1 promoter were inversely correlated with the NF-κB signaling activity along this sequence. In conclusion, these functionally interacting events drive CDX1 expression and contribute to intestinal metaplasia, epithelial dedifferentiation, and carcinogenesis in the human stomach.

Elevated serum osteopontin levels in idiopathic retroperitoneal fibrosis.

OBJECTIVES: To investigate the role of serum osteopontin concentrations for monitoring idiopathic retroperitoneal fibrosis. METHODS: In 22 patients with idiopathic retroperitoneal fibrosis serum concentrations of osteopontin were measured by an enzyme-linked immunosorbant assay and related to retrospectively gathered clinical data, contrast enhanced magnetic resonance imaging studies, and laboratory parameters. Patients with secondary causes, an inflammatory abdominal aortic aneurysm, and immunoglobulin G4-associated idiopathic retroperitoneal fibrosis were excluded. Twenty-two healthy volunteers served as controls. RESULTS: Serum osteopontin concentrations of patients with idiopathic retroperitoneal fibrosis were elevated compared to healthy controls (p=0.017) and correlated with the transverse diameter of the periaortic cuff as determined by imaging studies (ρ=0.549; p=0.008). Patients presenting with a diameter greater than 10mm had higher osteopontin concentrations than patients with smaller diameters (p=0.004). Increased inflammatory activity as determined by the presence of contrast enhancement in imaging studies (p<0.001) and the presence of typical symptoms (p=0.013) were associated with higher osteopontin concentrations. CONCLUSIONS: Serum osteopontin concentrations were elevated in patients with idiopathic retroperitoneal fibrosis. Increased concentrations correlated with the presence of clinical symptoms and extended disease or activity parameters on magnetic resonance imaging.

Angiotensin AT2 Receptor Stimulation Alleviates Collagen-Induced Arthritis by Upregulation of Regulatory T Cell Numbers.

The angiotensin AT2 receptor (AT2R) is a main receptor of the protective arm of the renin-angiotensin system and exerts for instance anti-inflammatory effects. The impact of AT2R stimulation on autoimmune diseases such as rheumatoid arthritis (RA) is not yet known. We investigated the therapeutic potential of AT2R-stimulation with the selective non-peptide AT2R agonist Compound 21 (C21) in collagen-induced arthritis (CIA), an animal model for inflammatory arthritis. Arthritis was induced by immunization of DBA/1J mice with collagen type II (CII). Prophylactic and therapeutic C21 treatment alleviates arthritis severity and incidence in CIA. Joint histology revealed significantly less infiltrates of IL-1 beta and IL-17A expressing cells and a well-preserved articular cartilage in C21- treated mice. In CIA, the number of CD4+CD25+FoxP3+ regulatory T (Treg) cells significantly increased upon C21 treatment compared to vehicle. T cell differentiation experiments demonstrated increased expression of FoxP3 mRNA, whereas IL-17A, STAT3 and IFN-gamma mRNA expression were reduced upon C21 treatment. In accordance with the mRNA data, C21 upregulated the percentage of CD4+FoxP3+ cells in Treg polarizing cultures compared to medium-treated controls, whereas the percentage of CD4+IL-17A+ and CD4+IFN-gamma+ T cells was suppressed. To conclude, C21 exerts beneficial effects on T cell-mediated experimental arthritis. We found that C21-induced AT2R-stimulation promotes the expansion of CD4+ regulatory T cells and suppresses IL-17A production. Thus, AT2R-stimulation may represent an attractive treatment strategy for arthritis.

Impact of dietary vitamin D on immunoregulation and disease pathology in lupus-prone NZB/W F1 mice.

Vitamin D (VD) deficiency is a highly prevalent worldwide phenomenon and is extensively discussed as a risk factor for the development of systemic lupus erythematosus (SLE) and other immune-mediated diseases. In addition, it is now appreciated that VD possesses multiple immunomodulatory effects. This study aims to explore the impact of dietary VD intake on lupus manifestation and pathology in lupus-prone NZB/W F1 mice and identify the underlying immunological mechanisms modulated by VD. Here, we show that low VD intake accelerates lupus progression, reflected in reduced overall survival and an earlier onset of proteinuria, as well higher concentrations of anti-double-stranded DNA autoantibodies. This unfavorable effect gained statistical significance with additional low maternal VD intake during the prenatal period. Among examined immunological effects, we found that low VD intake consistently hampered the adoption of a regulatory phenotype in lymphocytes, significantly reducing both IL-10-expressing and regulatory CD4+ T cells. This goes along with a mildly decreased frequency of IL-10-expressing B cells. We did not observe consistent effects on the phenotype and function of innate immune cells, including cytokine production, costimulatory molecule expression, and phagocytic capacity. Hence, our study reveals that low VD intake promotes lupus pathology, likely via the deviation of adaptive immunity, and suggests that the correction of VD deficiency might not only exert beneficial functions by preventing osteoporosis but also serve as an important module in prophylaxis and as an add-on in the treatment of lupus and possibly other immune-mediated diseases. Further research is required to determine the most appropriate dosage, as too-high VD serum levels may also induce adverse effects, possibly also on lupus pathology.

CMTM6-Deficient Monocytes in ANCA-Associated Vasculitis Fail to Present the Immune Checkpoint PD-L1.

Objectives: ANCA-associated vasculitides (AAV) affect small- and medium-sized blood vessels. In active disease, vessel wall infiltrates are mainly composed of monocytes and macrophages. Immune checkpoint molecules are crucial for the maintenance of self-tolerance and the prevention of autoimmune diseases. After checkpoint inhibitor therapy, the development of autoimmune vasculitis has been observed. However, defects of immune checkpoint molecules in AAV patients have not been identified yet. Methods: Monocytes and monocyte-derived macrophages from AAV patients and healthy age-matched controls were tested for surface expression of immunoinhibitory checkpoint programmed cell death ligand-1 (PD-L1). Using in vitro co-culture approaches, the effect of monocyte PD-L1 expression on CD4+ T cell activation and proliferation was tested. Results: Monocytes from AAV patients displayed lower PD-L1 expression and a defective PD-L1 presentation upon activation, an effect that was correlated with disease activity. Lower PD-L1 expression was due to increased lysosomal degradation of PD-L1 in AAV monocytes. We identified a reduced expression of CMTM6, a protein protecting PD-L1 from lysosomal breakdown, as the underlying molecular defect. PD-L1low AAV monocytes showed increased stimulatory capacity and induced T cell activation and proliferation. Inhibiting lysosomal function corrected this phenotype by increasing PD-L1, thus normalizing the pro-stimulatory behavior of AAV monocytes. Conclusions: This study identifies a defect of the immunoinhibitory checkpoint PD-L1 in monocytes from patients with AAV. Low expression of CMTM6 results in enhanced lysosomal degradation of PD-L1, thus providing insufficient negative signaling to T cells. Correcting this defect by targeting lysosomal function may represent a novel strategy to treat AAV.

Low-Salt Diet Attenuates B-Cell- and Myeloid-Cell-Driven Experimental Arthritides by Affecting Innate as Well as Adaptive Immune Mechanisms.

A link between high sodium chloride (salt) intake and the development of autoimmune diseases was previously reported. These earlier studies demonstrated exacerbation of experimental autoimmune encephalomyelitis and colitis by excess salt intake associated with Th17- and macrophage-mediated mechanisms. Little is known about the impact of dietary salt intake on experimental arthritides. Here, we investigated if salt restriction can exert beneficial effects on collagen-induced arthritis (CIA) and K/BxN serum transfer-induced arthritis (STIA). CIA depends on both adaptive and innate immunity, while STIA predominantly mimics the innate immune cell-driven effector phase of arthritis. In both models, low salt (LS) diet significantly decreased arthritis severity compared to regular salt (RS) and high salt (HS) diet. We did not observe an aggravation of arthritis with HS diet compared to RS diet. Remarkably, in STIA, LS diet was as effective as IL-1 receptor blocking treatment. Complement-fixing anti-CII IgG2a antibodies are associated with inflammatory cell infiltration and cartilage destruction. LS diet reduced anti-CII IgG2a levels in CIA and decreased the anti-CII IgG2a/IgG1 ratios pointing toward a more Th2-like response. Significantly less inflammatory joint infiltrates and cartilage breakdown associated with reduced protein concentrations of IL-1 beta (CIA and STIA), IL-17 (CIA), and the monocyte chemoattractant protein-1 (MCP-1) (CIA) were detected in mice receiving LS diet compared to HS diet. However, we did not find a reduced IL-17A expression in CD4+ T cells upon salt restriction in CIA. Analysis of mRNA transcripts and immunoblots revealed a link between LS diet and inhibition of the p38 MAPK (mitogen-activated protein kinase)/NFAT5 (nuclear factor of activated T-cells 5) signaling axis in STIA. Further experiments indicated a decreased leukodiapedesis under LS conditions. In conclusion, dietary salt restriction ameliorates CIA and STIA, indicating a beneficial role of LS diet during both the immunization and effector phase of immune-mediated arthritides by predominantly modulating the humoral immunity and the activation status of myeloid lineage cells. Hence, salt restriction might represent a supportive dietary intervention not only to reduce cardiovascular risk, but also to improve human inflammatory joint diseases like rheumatoid arthritis.

Antibodies to the endoplasmic reticulum-resident chaperones calnexin, BiP and Grp94 in patients with rheumatoid arthritis and systemic lupus erythematosus.

OBJECTIVES: To investigate the presence of autoantibodies against mammalian chaperones of the endoplasmic reticulum (ER) in patients with RA and other immune-mediated diseases. METHODS: Sera from healthy donors, from early RA patients with two follow-up samples, patients with SLE, SSc and IBD were collected and analysed for anti-ER chaperone antibodies. Detection of serum IgG antibodies against immunoglobulin heavy chain binding protein (BiP), glucose-regulated protein 94 (Grp94) and calnexin was carried out using ELISA. The specificity of sera positive for individual ER chaperones was confirmed by immunoblotting. Statistical analysis was performed using Welch's t-test, Mann-Whitney U-test, partial correlation and Pearson's correlation. RESULTS: In patients with RA and SLE, autoantibody titres against BiP, Grp94 and calnexin were significantly higher than those in healthy controls. These autoantibodies were detectable in patients with early RA and titres remained stable for at least 6-12 months. Also several SSc and IBD patients exhibited autoantibodies against these ER chaperones; however, titres and frequencies were lower than in RA or SLE patients. Furthermore, anti-calnexin antibodies correlated significantly with the presence of BiP and Grp94 autoantibodies in patients with RA and SLE. CONCLUSION: Calnexin and Grp94 were identified as novel autoantigens in RA and calnexin in SLE. Since calnexin, Grp94 and BiP are ER-resident proteins of eukaryotic cells, our data suggest that autoantibody generation against ER chaperones is independent of initial exposure to the corresponding bacterial chaperones; rather, ER chaperones may represent genuine autoantigens.

Cell-Type Targeted NF-kappaB Inhibition for the Treatment of Inflammatory Diseases.

Deregulated NF-k activation is not only involved in cancer but also contributes to the pathogenesis of chronic inflammatory diseases like rheumatoid arthritis (RA) and multiple sclerosis (MS). Ideally, therapeutic NF-KappaB inhibition should only take place in those cell types that are involved in disease pathogenesis to maintain physiological cell functions in all other cells. In contrast, unselective NF-kappaB inhibition in all cells results in multiple adverse effects, a major hindrance in drug development. Hitherto, various substances exist to inhibit different steps of NF-kappaB signaling. However, powerful tools for cell-type specific NF-kappaB inhibition are not yet established. Here, we review the role of NF-kappaB in inflammatory diseases, current strategies for drug delivery and NF-kappaB inhibition and point out the "sneaking ligand" approach. Sneaking ligand fusion proteins (SLFPs) are recombinant proteins with modular architecture consisting of three domains. The prototype SLC1 binds specifically to the activated endothelium and blocks canonical NF-kappaB activation. In vivo, SLC1 attenuated clinical and histological signs of experimental arthritides. The SLFP architecture allows an easy exchange of binding and effector domains and represents an attractive approach to study disease-relevant biological targets in a broad range of diseases. In vivo, SLFP treatment might increase therapeutic efficacy while minimizing adverse effects.

Vegan diet reduces neutrophils, monocytes and platelets related to branched-chain amino acids - A randomized, controlled trial.

BACKGROUND: Vegan diet (VD) has improved inflammatory activity in patients with rheumatoid arthritis (RA) in several small controlled trials. The underlying mechanism remains widely unclear. We investigated the effect of a VD in comparison to a meat-rich diet (MD) on markers of inflammation (which have been shown to be relevant in patients with RA) in healthy volunteers. METHODS: 53 healthy, omnivore subjects were randomized to a controlled VD (n = 26) or MD (n = 27) for 4 weeks following a pre-treatment phase of a one week controlled mixed diet. Primary parameters of interest were sialylation of immunoglobulins, percentage of regulatory T-cells and level of interleukin 10 (IL10). Usual care immune parameters used in patients with RA and amino acid serum levels as well as granulocytes and monocytes colony stimulating factor (GM-CSF) serum levels were secondary parameters. RESULTS: In the VD group, total leukocyte, neutrophil, monocyte and platelet counts decreased and after four weeks they were significantly lower compared to the MD group (ANCOVA: leukocytes p = 0.003, neutrophils p = 0.001, monocytes p = 0.032, platelets p = 0.004). Leukocytes, neutrophils, monocytes, and platelets correlated with each other and likewise conform with serum levels of branched-chain amino acids, which were significantly lower in the VD compared to the MD group. The primary parameters did not differ between the groups and BMI remained stable in the two groups. CONCLUSION: Four weeks of a controlled VD affected the number of neutrophils, monocytes and platelets but not the number or function of lymphocytes. The relation with branched-chain amino acids and GM-CSF suggests a mode of action via the mTOR signaling pathway. REGISTERED AT: http://www.drks.de (German Clinical Trial register) at DRKS00011963.

The crystal structure of the pathogenic collagen type II-specific mouse monoclonal antibody CIIC1 Fab: structure to function analysis.

Monoclonal anti-collagen type II antibody CIIC1 is an arthritogenic autoantibody, which induces arthritis in mice. We crystallized and solved the structure of CIIC1 Fab molecule. Analysis of structure revealed an interaction between the CDR regions of one Fab to the CH1 domain of another Fab, which resembles an antibody-antigen interaction. ELISA experiments confirmed the cross-reactivity of both the full CIIC1 antibody and a single chain Fv fragment to other anti-collagen antibodies which are of different isotypes and epitope specificity. The rheumatoid factor like reactivity of CIIC1 antibody together with its collagen type II specificity may explain the pathogenicity of this antibody.

Association of High Mobility Group Box Chromosomal Protein 1 and Receptor for Advanced Glycation End Products Serum Concentrations With Extraglandular Involvement and Disease Activity in Sjögren's Syndrome.

OBJECTIVE: To assess serum levels of high mobility group box chromosomal protein 1 (HMGB-1) and the soluble receptor for advanced glycation end products (sRAGE) in patients with Sjögren's syndrome (SS) and explore correlations with disease activity. METHODS: Thirty-nine patients with SS and 21 healthy controls were included in this cross-sectional study. Clinical and laboratory values were obtained from all patients. Disease activity was assessed using the European League Against Rheumatism SS Disease Activity Index (ESSDAI). Serum samples were collected and HMGB-1 and sRAGE levels were measured using enzyme-linked immunosorbent assay (ELISA), and HMGB-1 concentrations were semiquantified by Western blotting. RESULTS: In ELISA, HMGB-1 serum levels did not differ between healthy controls and patients with SS (P = 0.783). When measured by semiquantitative Western blotting, HMGB-1 levels were increased in patients with SS compared to healthy controls (P = 0.012). HMGB-1 serum levels detected by Western blotting were higher in patients with extraglandular manifestations (P = 0.003) and were correlated with ESSDAI disease activity (r = 0.544, P < 0.0001). Furthermore, sRAGE was elevated in the sera of patients with SS (P = 0.003) compared to healthy controls and was also correlated with the ESSDAI (r = 0.545, P = 0.002). CONCLUSION: Serum levels of total HMGB-1 and sRAGE were elevated in patients with SS compared to healthy controls and correlated with disease activity as measured by the ESSDAI. Patients with extraglandular involvement had high serum levels of HMGB-1.

Serological lymphocytic activity and patient-reported outcomes in Sjögren's syndrome.

This study was set to investigate whether serum markers of lymphocytic activity are associated with patient-reported outcomes in Sjögren's syndrome (SS). Forty-six patients with SS were included in this cross-sectional study. Patients with monoclonal gammopathy, history of malignant lymphoma, or with secondary SS were excluded. Serum levels of IgG, ß2-microglobulin (ß2M), soluble interleukin-2 receptor (sIL2-R), and free light chains (FLC) were assessed. Systemic disease activity was measured by the EULAR SS disease activity index (ESSDAI). Patient-reported symptoms were recorded by visual analogue scales (VAS) of pain, fatigue, and dryness, as compiled in the EULAR SS patient-reported index (ESSPRI). Depressive symptoms were determined by the Patient Health Questionnaire 9 (PHQ-9). Serum concentrations of κFLC (r = 0.491, p = 0.001), λFLC (r = 0.326, p = 0.027), and ß2M (r = 0.421, p = 0.004) correlated with the ESSDAI, whereas sIL-2R and IgG did not. No correlations between serum markers of lymphocytic activity and the ESSPRI, or single VAS measures of pain, dryness, or fatigue, were found. In patients with VAS fatigue scores in the upper quartile, sIL-2R serum levels were even decreased (p = 0.019). Only depressive symptoms as determined by PHQ-9 were positively correlated with fatigue (r = 0.536, p < 0.001). In this well-defined cohort of patients with SS, serological lymphocytic activity was not correlated with patient-reported outcomes and sIL-2R levels were even decreased in patients with high fatigue scores. Only depressive symptoms were correlated with fatigue. This highlights the need to further understand the link between inflammation and disease characteristics in SS.

Interaction of histones with phospholipids--implications for the exposure of histones on apoptotic cells.

The generation of autoantibodies against chromatin is a hallmark of the multifactorial autoimmune disease systemic lupus erythematosous (SLE). Impaired clearance of apoptotic cells together with the release of nuclear autoantigens are supposed to contribute to the loss of self-tolerance in SLE. Phospholipids such as phosphatidylserine (PS) and phosphatidylethanolamine (PE) are exposed on the surfaces of apoptotic cells and on apoptotic blebs. Also histones/nucleosomes can be detected on apoptotic cells; however, their binding motifs are still unknown. Therefore, we investigated the interaction of PS, PE, phosphatidylcholine (PC), and cardiolipin (CL) with histones H1, H2A, H2B, H3, and H4 by surface plasmon resonance (SPR). Strong binding to phospholipids was found for all histones, with H2A displaying the highest binding affinity to all phospholipids investigated. Hence, phospholipids including PS and PE may contribute to the binding of histones to surfaces and blebs of apoptotic cells. Moreover, histones/nucleosomes complexed to uningested apoptotic membrane structures may foster autoimmunity towards nuclear compounds.

The "sneaking-ligand" approach: cell-type specific inhibition of the classical NF-κB pathway.

The intracellular delivery of molecules across the plasma membrane represents a major obstacle. The conjugation of cell-permeable peptides (CPPs) to proteins promotes the uptake and internalization. However, uptake of CPPs is receptor independent and not cell-type specific. Recently, we established the "sneaking-ligand" approach which is based on multimodular recombinant fusion proteins that consist of three modules connected with serine-glycine linkers. Module one is responsible for receptor-mediated endocytosis; module two supports translocation into the cytoplasm so that the effector module three can interact with its binding partner in the cytoplasm. For NF-κB inhibition, we described an NF-κB inhibitor that targets selectively the activated endothelium via an oligopeptide motif. Upon E-selectin-mediated endocytosis, the Pseudomonas exotoxin A domain II (ETAII) translocates the NEMO-binding peptide to the cytoplasm interfering with IκB kinase complex assembly. Inflammatory autoimmune diseases are triggered, but also resolved by a variety of cell types. Therefore, the inhibition of NF-κB should be restricted to those cells that are crucially involved in the pathogenesis of inflammatory diseases. A general blockade of NF-κB may result in severe immunosuppression and possibly in organ dysfunction or damage. The "sneaking-ligand" approach could minimize the risks of therapeutic interventions and identify disease-relevant cell types. Here we describe the recombinant expression and purification of the E-selectin-specific "sneaking-ligand construct" (SLC1) and its ability to inhibit cytokine-induced NF-κB activation in vitro.