Leucine-Rich Glioma-Inactivated 1 (LGI1) Protein Stimulates Proliferation and IL-10 Production in Peripheral Blood Mononuclear Cells of Patients with LGI1 Antibody-Mediated Autoimmune Encephalitis In Vitro.

Limbic encephalitis (LE) due to anti-leucine-rich glioma-inactivated 1 (LGI1) antibodies is an autoimmune disease characterized by distinct clinical features unique to LGI1 LE, such as faciobrachial dystonic seizures. However, it is unclear whether an additional disease-related LGI1 antigen-specific T cell response is involved in the pathogenesis of this disease. To address this question, we studied the effect of recombinant LGI1 on the proliferation and effector-specific cytokine production (IFN-γ, IL-5, IL-10, and IL-17) of peripheral blood mononuclear cells (PBMCs) from patients with LGI1 LE and healthy controls. We observed that recombinant LGI1 stimulated the proliferation of PBMCs from patients with LGI1 LE, but not from healthy controls. Cytokine measurement of cell culture supernatants from PBMCs incubated with recombinant LGI1 revealed a highly significant increase in IL-10 release in PBMCs from patients with LGI1 LE in comparison with healthy controls. These results suggest that LGI1-mediated stimulation of PBMCs from patients with LGI1 LE leads to the establishment of an IL-10-dominated immunosuppressive cytokine milieu, which may inhibit Th1 differentiation and support B cell proliferation, IgG production, and IgG subclass switching.

Human glycoprotein-2 expressed in Brunner glands - A putative autoimmune target and link between Crohn's and coeliac disease.

Glycoprotein 2 (GP2) is an autoantigen in Crohn's (CD) and coeliac disease (CeD). We assessed GP2-isoform (GP21-4)-expression in intestinal biopsies of paediatric patients with CD, CeD, ulcerative colitis (UC), and healthy children (HC). Transcription of GP21-4 was elevated in proximal small intestine in CeD and CD patients (only GP22/4) compared to jejunum (CeD/CD) and large bowel (CD). CeD patients demonstrated higher duodenal GP22/4-mRNA levels compared to HC/UC patients whereas CD patients showed higher GP24-mRNA levels compared to UC patients. Duodenal synthesis of only small GP2 isoforms (GP23/4) was demonstrated in epithelial cells in patients/HC and in Brunner glands (also large isoforms) with a more frequent apical location in CD/CeD patients. All four GP2 isoforms interacted with gliadin and phosphopeptidomannan. Gliadin digestion improved binding to GP2 isoforms. GP21-4 binding to CeD/CD-related antigens, elevated duodenal GP21-4-mRNA transcription, and GP2-protein secretion in Brunner glands of CeD/CD patients suggest an autoimmune CeD/CD link.

The brain reacting to COVID-19: analysis of the cerebrospinal fluid proteome, RNA and inflammation.

Patients with COVID-19 can have a variety of neurological symptoms, but the active involvement of central nervous system (CNS) in COVID-19 remains unclear. While routine cerebrospinal fluid (CSF) analyses in patients with neurological manifestations of COVID-19 generally show no or only mild inflammation, more detailed data on inflammatory mediators in the CSF of patients with COVID-19 are scarce. We studied the inflammatory response in paired CSF and serum samples of patients with COVID-19 (n = 38). Patients with herpes simplex virus encephalitis (HSVE, n = 10) and patients with non-inflammatory, non-neurodegenerative neurological diseases (n = 28) served as controls. We used proteomics, enzyme-linked immunoassays, and semiquantitative cytokine arrays to characterize inflammatory proteins. Autoantibody screening was performed with cell-based assays and native tissue staining. RNA sequencing of long-non-coding RNA and circular RNA was done to study the transcriptome. Proteomics on single protein level and subsequent pathway analysis showed similar yet strongly attenuated inflammatory changes in the CSF of COVID-19 patients compared to HSVE patients with, e.g., downregulation of the apolipoproteins and extracellular matrix proteins. Protein upregulation of the complement system, the serpin proteins pathways, and other proteins including glycoproteins alpha-2 and alpha-1 acid. Importantly, calculation of interleukin-6, interleukin-16, and CXCL10 CSF/serum indices suggest that these inflammatory mediators reach the CSF from the systemic circulation, rather than being produced within the CNS. Antibody screening revealed no pathological levels of known neuronal autoantibodies. When stratifying COVID-19 patients into those with and without bacterial superinfection as indicated by elevated procalcitonin levels, inflammatory markers were significantly (p < 0.01) higher in those with bacterial superinfection. RNA sequencing in the CSF revealed 101 linear RNAs comprising messenger RNAs, and two circRNAs being significantly differentially expressed in COVID-19 than in non-neuroinflammatory controls and neurodegenerative patients. Our findings may explain the absence of signs of intrathecal inflammation upon routine CSF testing despite the presence of SARS-CoV2 infection-associated neurological symptoms. The relevance of blood-derived mediators of inflammation in the CSF for neurological COVID-19 and post-COVID-19 symptoms deserves further investigation.

Serum and CSF cytokine levels mirror different neuroimmunological mechanisms in patients with LGI1 and Caspr2 encephalitis.

Changes in levels of cytokines or soluble receptors in biological fluids may provide information on immunological pathomechanisms underlying the respective diseases. Here, we studied cytokine patterns of patients with autoimmune encephalitis (AE) before and after immunosuppressive treatment in order to identify possible biomarker candidates and to look for putatively involved pathomechanisms. We performed measurements in Cerebrospinal fluid (CSF) and serum of 7 patients suffering from AE with antibodies (ab) against Leucine-rich glioma-inactivated-protein 1 (LGI1) and 9 AE patients with Contactin-associated protein-like 2 (Caspr2) ab recruited from two tertiary AE centers in Magdeburg and Berlin, Germany. In the Magdeburg samples before and after treatment were available for the measurements and in the Berlin cohort samples were collected after treatment was initiated. First, we used a human cytokine array comprising 36 cytokines or soluble receptors to screen for biomarkers in CSF samples of 8 AE (before and after treatment), 4 herpes-simplex virus meningoencephalitis patients and 4 controls without neuroinflammation. Next, CCL2, CXCl10, CXCl13, Il -6 and sICAM1 were chosen as candidates and measured in CSF and serum with specific ELISA systems in all 16 AE patients, 14 controls without neuroinflammation and 7 herpes-simplex virus meningitis patients. Clinical outcome was assessed via modified Rankin scale. LGI1 and Caspr2 abs from the Magdeburg cohort were purified by chromatography. IgG subclasses of these LGI1 or Caspr2 abs were identified by immunoblot analysis. The levels of most candidate parameters were higher in the CSF of Caspr2 than of LGI1 AE patients and controls, but there were no significant changes of cytokine concentrations before and after initiating treatment. Thus, these parameters seem unsuited as surrogate biomarkers of disease. Significantly higher levels were observed in the CSFs of Caspr2 AE patients (CXCL13 and sICAM1) as well as in the serum of Caspr2 (CXCL10) and LGI1 AE patients (CXCL13) in comparison to control samples. These results suggest that neuro-immunological pathomechanisms may differ between Caspr2 and LGI1 AE patients. Caspr2 AE seems to elicit a higher immune response than LGI1 AE, which has no correlation to the respective IgG subclass combination of AE specific abs involved in each type of disease.

Serological diagnosis and prognosis of severe acute pancreatitis by analysis of serum glycoprotein 2.

BACKGROUND: Glycoprotein 2 (GP2), the pancreatic major zymogen granule membrane glycoprotein, was reported to be elevated in acute pancreatitis in animal models. METHODS: Enzyme-linked immunosorbent assays (ELISAs) were developed to evaluate human glycoprotein 2 isoform alpha (GP2a) and total GP2 (GP2t) as specific markers for acute pancreatitis in sera of 153 patients with acute pancreatitis, 26 with chronic pancreatitis, 125 with pancreatic neoplasms, 324 with non-pancreatic neoplasms, 109 patients with liver/biliary disease, 67 with gastrointestinal disease, and 101 healthy subjects. GP2a and GP2t levels were correlated with procalcitonin and C-reactive protein in 152 and 146 follow-up samples of acute pancreatitis patients, respectively. RESULTS: The GP2a ELISA revealed a significantly higher assay accuracy in contrast to the GP2t assay (sensitivity ≤3 disease days: 91.7%, specificity: 96.7%, positive likelihood ratio [LR+]: 24.6, LR-: 0.09). GP2a and GP2t levels as well as prevalences were significantly elevated in early acute pancreatitis (≤3 disease days) compared to all control cohorts (p<0.05, respectively). GP2a and GP2t levels were significantly higher in patients with severe acute pancreatitis at admission compared with mild cases (p<0.05, respectively). Odds ratio for GP2a regarding mild vs. severe acute pancreatitis with lethal outcome was 7.8 on admission (p=0.0222). GP2a and GP2t levels were significantly correlated with procalcitonin [Spearman's rank coefficient of correlation (ρ)=0.21, 0.26; p=0.0110, 0.0012; respectively] and C-reactive protein (ρ=0.37, 0.40; p<0.0001; respectively). CONCLUSIONS: Serum GP2a is a specific marker of acute pancreatitis and analysis of GP2a can aid in the differential diagnosis of acute upper abdominal pain and prognosis of severe acute pancreatitis.

Evidence of Crohn's disease-related anti-glycoprotein 2 antibodies in patients with celiac disease.

BACKGROUND: Autoantibodies to exocrine-pancreatic glycoprotein 2 (anti-GP2) are Crohn's disease (CD) markers. However, CD-specific antibodies have also been found in celiac-disease (CeD) patients, in which type 1 diabetes-specific autoantibodies against endocrine pancreatic targets can be present. We investigated whether anti-GP2 are also present in CeD, a disease like CD which is also characterised by intestinal mucosal inflammation with barrier impairment. METHODS: Antibodies against GP2, tissue transglutaminase (tTG), deamidated gliadin (dGD), glutamic decarboxylase (GAD), and islet antigen-2 (IA2) were tested in sera from 73 CD patients, 90 blood donors (BD), and 79 (58 de novo) CeD patients (2 consecutive sera were available from 40 patients). RESULTS: IgA and/or IgG anti-GP2 were found in 15/79 (19.0%) CeD patients on at least one occasion, in 25/73 (34.2%) CD patients, and in 4/90 (4.4%) BD (CeD vs. CD, p=0.042; BD vs. CeD and CD, p<0.001, respectively). Amongst the 58 de novo CeD patients, anti-GP2 IgA and/or IgG were present in 11 (19.0%). Anti-GP2 IgA was significantly less prevalent in CeD compared with CD (p=0.004). Anti-GP2 IgA and IgG in CD patients demonstrated a significantly higher median level compared to patients with CeD (p<0.001, p=0.008, respectively). IgA anti-GP2 levels correlated significantly with IgA anti-tTG and anti-dGD levels in CeD Spearman's coefficient of rank correlation (ρ)=0.42, confidence interval (CI): 0.26-0.56, p<0.001; ρ=0.54, CI 0.39-0.65, p<0.001, respectively. CONCLUSIONS: The presence of anti-GP2 in CeD patients supports the notion that loss of tolerance to GP2 can probably be a manifestation of an autoinflammatory process in this intestinal disorder.

Fully automated analysis of chemically induced γH2AX foci in human peripheral blood mononuclear cells by indirect immunofluorescence.

Analysis of phosphorylated histone protein H2AX (γH2AX) foci is currently the most sensitive method to detect DNA double-strand breaks (DSB). This protein modification has the potential to become an individual biomarker of cellular stress, especially in the diagnosis and monitoring of neoplastic diseases. To make γH2AX foci analysis available as a routine screening method, different software approaches for automated immunofluorescence pattern evaluation have recently been developed. In this study, we used novel pattern recognition algorithms on the AKLIDES® platform to automatically analyze immunofluorescence images of γH2AX foci and compared the results with visual assessments. Dose- and time-dependent γH2AX foci formation was investigated in human peripheral blood mononuclear cells (PBMCs) treated with the chemotherapeutic drug etoposide (ETP). Moreover, the AKLIDES system was used to analyze the impact of different immunomodulatory reagents on γH2AX foci formation in PBMCs. Apart from γH2AX foci counting the use of novel pattern recognition algorithms allowed the measurement of their fluorescence intensity and size, as well as the analysis of overlapping γH2AX foci. The comparison of automated and manual foci quantification showed overall a good correlation. After ETP exposure, a clear dose-dependent increase of γH2AX foci formation was evident using the AKLIDES as well as Western blot analysis. Kinetic experiments on PBMCs incubated with 5 µM ETP demonstrated a peak in γH2AX foci formation after 4 to 8 h, while a removal of ETP resulted in a strong reduction of γH2AX foci after 1 to 4 h. In summary, this study demonstrated that the AKLIDES system can be used as an efficient automatic screening tool for γH2AX foci analysis by providing new evaluation features and facilitating the identification of drugs which induce or modulate DNA damage.

Antibody Properties Associate with Clinical Phenotype in LGI1 Encephalitis.

Autoimmune encephalitis (AE) associated with autoantibodies against leucine-rich glioma-inactivated protein-1 (LGI1) can present with faciobrachial dystonic seizures (FBDS) and/or limbic encephalitis (LE). The reasons for this heterogeneity in phenotypes are unclear. We performed autoantibody (abs) characterization per patient, two patients suffering from LE and two from FBDS, using isolated antibodies specified with single amino acid epitope mapping. Electrophysiological slice recordings were conducted alongside spine density measurements, postsynaptic Alpha-amino-3-hydoxy-5-methyl-4-isoaxole-proprionate-receptors (AMPA-R) and N-methyl-D-aspartate-receptors receptor (NMDA-R) cluster counting. These results were correlated with the symptoms of each patient. While LGI1 abs from LE patients mainly interacted with the Leucine-rich repeat section of LGI1, abs from both FBDS patients also recognized the Epitempin section as well. Six-hour incubation of mouse hippocampal slices with LE patients autoantibodies but not from the FBDS patients resulted in a significant decline in long-term potentiation (p = 0.0015) or short-term plasticity at CA3-CA1 neurons and in decreased hippocampal synaptic density. Cluster differentiation showed no decrease in postsynaptic AMPA-R and NMDA-R. LGI1 autoantibodies selected by phenotype show an almost distinct epitope pattern, elicit disparate functional effects on hippocampal neurons, and cause divergent effects on spine density. This data illuminates potential pathomechanisms for disease heterogeneity in LGI1 AE.

Dipeptidyl peptidase IV, aminopeptidase N and DPIV/APN-like proteases in cerebral ischemia.

BACKGROUND: Cerebral inflammation is a hallmark of neuronal degeneration. Dipeptidyl peptidase IV, aminopeptidase N as well as the dipeptidyl peptidases II, 8 and 9 and cytosolic alanyl-aminopeptidase are involved in the regulation of autoimmunity and inflammation. We studied the expression, localisation and activity patterns of these proteases after endothelin-induced occlusion of the middle cerebral artery in rats, a model of transient and unilateral cerebral ischemia. METHODS: Male Sprague-Dawley rats were used. RT-PCR, immunohistochemistry and protease activity assays were performed at different time points, lasting from 2 h to 7 days after cerebral ischemia. The effect of protease inhibitors on ischemia-dependent infarct volumes was quantified 7 days post middle cerebral artery occlusion. Statistical analysis was conducted using the t-test. RESULTS: Qualitative RT-PCR revealed these proteases in ipsilateral and contralateral cortices. Dipeptidyl peptidase II and aminopeptidase N were up-regulated ipsilaterally from 6 h to 7 days post ischemia, whereas dipeptidyl peptidase 9 and cytosolic alanyl-aminopeptidase were transiently down-regulated at day 3. Dipeptidyl peptidase 8 and aminopeptidase N immunoreactivities were detected in cortical neurons of the contralateral hemisphere. At the same time point, dipeptidyl peptidase IV, 8 and aminopeptidase N were identified in activated microglia and macrophages in the ipsilateral cortex. Seven days post artery occlusion, dipeptidyl peptidase IV immunoreactivity was found in the perikarya of surviving cortical neurons of the ipsilateral hemisphere, whereas their nuclei were dipeptidyl peptidase 8- and amino peptidase N-positive. At the same time point, dipeptidyl peptidase IV, 8 and aminopeptidase N were targeted in astroglial cells. Total dipeptidyl peptidase IV, 8 and 9 activities remained constant in both hemispheres until day 3 post experimental ischemia, but were increased (+165%) in the ipsilateral cortex at day 7. In parallel, aminopeptidase N and cytosolic alanyl-aminopeptidase activities remained unchanged. CONCLUSIONS: Distinct expression, localization and activity patterns of proline- and alanine-specific proteases indicate their involvement in ischemia-triggered inflammation and neurodegeneration. Consistently, IPC1755, a non-selective protease inhibitor, revealed a significant reduction of cortical lesions after transient cerebral ischemia and may suggest dipeptidyl peptidase IV, aminopeptidase N and proteases with similar substrate specificity as potentially therapy-relevant targets.

Methodologic issues in the measurement of interleukin-16 in clinical blood samples using immunoassays.

Quantitation of interleukin-16 (IL-16) in clinical blood samples has strongly increased, since IL-16 appears to be involved in the pathogenesis of several inflammatory diseases. IL-16 is synthesized in the cell cytoplasm as precursor protein (pro-IL-16), which can be processed by caspase-3 into N-terminal (N-IL-16) and C-terminal (C-IL-16) fragments. C-IL-16 is described to be subsequently secreted. Using commercially available IL-16 ELISA, a pro-IL-16 ELISA and immunoprecipitation analysis, we investigated, whether type and handling of blood samples influence IL-16 quantitation and whether existing IL-16 ELISA are specific for C-IL-16. We observed that cell-rich plasma samples reflect falsely-elevated IL-16 concentrations due to cell contaminations. Interestingly, not C-IL-16, but pro-IL-16 represents the major IL-16 form in cell-rich plasma samples. Notably, commercially IL-16 ELISA could not distinguish between C-IL-16 and pro-IL-16. Thus, cell-rich plasma samples should not be used for IL-16 measurements and new methods are necessary for quantitation of C-IL-16 and pro-IL-16 uniquely.

Zinc aspartate suppresses T cell activation in vitro and relapsing experimental autoimmune encephalomyelitis in SJL/J mice.

Zinc is an essential trace element with a critical role in normal growth and development and in immune homeostasis. Zinc deficiency impairs both the innate and the adaptive immune system and can be normalized by zinc supplementation. On the other end of the spectrum, high dosages of zinc diminish immune cell functions similar to zinc deficiency. Here, we investigated the influence of zinc aspartate on proliferation and cytokine production of stimulated human T cells and mouse splenocytes in vitro. Furthermore, the effect of zinc aspartate was examined in mice with experimental autoimmune encephalomyelitis (EAE), an animal model of Multiple Sclerosis (MS) with a Th1/Th17 T cell-mediated immunopathogenesis. Zinc aspartate suppressed proliferation as well as IL-2, IL-10 and IL-17 production in stimulated human T cells and mouse splenocytes. Importantly, administration of a medium range dose of 30 µg/day zinc aspartate [1.5 mg/kg body weight (BW)] in a therapeutic manner led to a significant reduction of the clinical severity of the EAE during the first relapse of the disease. A lower zinc aspartate dose (6 µg/day, 0.3 mg/kg BW) had no significant therapeutic effect on the severity of the EAE, while administration of higher zinc aspartate amounts (120 µg/day, 6 mg/kg BW) led to more severe disease. Taken together, our data suggest that zinc aspartate can modulate activation, proliferation and cytokine production of effector T cells in vitro and in vivo and that activated autoreactive T cells may be potential therapeutic targets of tightly controlled zinc supplementation in autoimmune diseases like MS.

PETIR-001, a dual inhibitor of dipeptidyl peptidase IV (DP IV) and aminopeptidase N (APN), ameliorates experimental autoimmune encephalomyelitis in SJL/J mice.

Cellular dipeptidyl peptidase IV (DP IV, CD26) and amino-peptidase N (APN, CD13) play regulatory roles in T cell activation and represent potential targets for treatment of inflammatory disorders. We have developed a novel therapeutic strategy, 'peptidase-targeted Immunoregulation' (PETIR™), which simultaneously targets both cellular DP IV and APN via selective binding sites different from the active sites with a single inhibitor. To prove the therapeutic concept of PETIR™ in autoimmunity of the central nervous system (CNS), we evaluated the effect of a single substance, PETIR-001, in an animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE) in SJL/J mice. Administration of PETIR-001 significantly delayed and decreased clinical signs of active EAE, when given in a therapeutic manner intraperitoneally from day 15 to day 24 after induction of EAE. Both the acute phase and the first relapse of EAE were markedly inhibited. Importantly, a similar therapeutic benefit was obtained after oral administration of PETIR-001 from day 12 to day 21 after disease induction. Our results demonstrate that PETIR-001 exhibits a therapeutic effect on EAE in SJL/J mice. Thus, PETIR™ represents a novel and efficient therapeutic approach for immunotherapy of CNS inflammation.

The zymogen granule protein 2 (GP2) binds to scavenger receptor expressed on endothelial cells I (SREC-I).

The pancreatic zymogen granule membrane protein (GP2) is expressed by pancreatic acinar cells and M cells of the ileum. GP2 is the closest related homologue of the urine resident Tamm-Horsfall protein (THP). Recently, it was shown that THP is a ligand of various scavenger receptors (SRs). Therefore, we were interested, if GP2 has similar properties. cDNA of different SRs was stably transfected into a murine thymoma cell line. GP2 was recombinantly expressed, purified and biotinylated. Binding or uptake of GP2 by transfected cells or monocyte-derived dendritic cells (moDCs) was analyzed by flow-cytometry. GP2 is a binding partner of the scavenger receptor expressed on endothelial cells I (SREC-I) but not of SR-AI and SR-BI. The dissociation constant (K(d)) of GP2 binding to SREC-I is 41.3nM. SREC transfected cells are able to internalize GP2. moDCs express SREC-I and also bind and internalize GP2. Inhibition of SREC-I on moDCs with anti-SREC-I antibodies does not result in a decreased GP2 binding. Interaction of GP2 with SREC-I and uptake might have profound effects in antigen clearance and mediation of the immune response. In addition to SREC-I other presently unknown receptors for GP2 on DCs might be involved in this process.

Ratio and index of Neurofilament light chain indicate its origin in Guillain-Barré Syndrome.

OBJECTIVE: Neurofilament light chain (NfL) has been established as a biomarker of axonal damage in many diseases of the central nervous system (CNS). Increased levels of serum NfL (sNfL) can derive as well from damage in the peripheral nervous system (PNS) as from CNS, but little is known about the quantities contributing to sNfL. Peripheral nerve damage may be reflected by an increase in sNfL levels, while the NfL CSF/serum ratio and NfL index decreases. METHODS: We collected serum and cerebrospinal fluid (CSF) from 21 Guillain-Barré Syndrome (GBS) patients and measured NfL in serum and CSF and compared them with 19 neurologically healthy controls. RESULTS: In general, NfL in CSF and serum was significantly higher in GBS patients. Serum NfL was higher in GBS patients admitted to the intensive care unit (P = 0.02). Controls had a mean CSF/serum NfL ratio of 26.7 (ranging from 5.8 to 69.5) indicating a central origin of NfL. Three GBS patients had a similar range (23.9 to 42.7, mean 33.3) all of them with demyelinating pathology in the PNS. Eighteen GBS patients with axonal or mixed axonal-demyelinating pathology showed significantly lower CSF/serum ratios (0.02-12.2, mean 4.4), indicative of a peripheral origin of NfL. When applying the NfL index subdivisions remain the same. INTERPRETATION: These results demonstrate that the PNS is a relevant contributor to sNfL levels and that the distribution can be identified by a lowered NfL CSF/serum ratio of NfL index. Furthermore, acute or subacute polyneuropathies are likely confounding factors in interpreting sNfL levels in CNS diseases.

Generation and validation of murine monoclonal and camelid recombinant single domain antibodies specific for human pancreatic glycoprotein 2.

Pancreatic secretory zymogen-granule membrane glycoprotein 2 (GP2) has been identified as a major autoantigenic target in Crohn's disease patients. It was reported recently that a long (GP2a) and a short (GP2b) isoform of GP2 exist and that in the outcome of inflammatory bowel diseases (IBD) GP2-specific autoantibodies probably appear as new serological markers for diagnosis and therapeutic monitoring. To investigate this further and in order to establish diagnostic tools for the discrimination of both GP2 isoforms, a set of different murine monoclonal and camelid recombinant single domain antibodies (camelid VHH) was generated and validated in various enzyme-linked immunosorbent assay (ELISA) formats, immunofluorescence on transgenic cell lines and immunohistochemistry on monkey pancreas tissue sections. Out of six binders identified, one was validated as highly specific for GP2a. This murine monoclonal antibody (mAb) was used as capture antibody in construction of a sandwich ELISA for the detection of GP2a. Camelid VHHs or a second murine mAb served as detection antibodies in this system. All antibodies were also able to stain GP2a or GP2b on transgenic cell lines as well as on pancreatic tissue in immunohistochemistry. The KD values measured for the camelid VHHs were between 7 nM and 23pM. This set of specific binders will enable the development of suitable diagnostic tools for GP2-related studies in IBD.

Dual inhibition of dipeptidyl peptidase IV and aminopeptidase N suppresses inflammatory immune responses.

The ectopeptidases dipeptidyl peptidase IV (DP IV, CD26) and aminopeptidase N (APN, CD13) are known to regulate T cell activation. Since selective inhibitors of DP IV and APN suppress DNA synthesis and cytokine production of stimulated T cells in a TGF-beta1-dependent manner, we tested whether combined application of DP IV and APN inhibitors enhances this immunomodulatory effect. The results show that simultaneous application of DP IV and APN inhibitors significantly suppressed DNA synthesis in mitogen- or anti-CD3-stimulated human T cells in vitro when compared to the use of a single DP IV or APN inhibitor. Moreover, the combined action of DP IV and APN inhibitors markedly increased TGF-beta1 production associated with the observed immunosuppressive effects. In vivo, targeting both DP IV and APN led to a potent treatment of experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis (MS). This review summarizes the evidence for the role of both enzymes in T cell activation in vitro and in vivo and provides a rationale for using combined and dual peptidase inhibitors to treat autoimmune diseases like MS.

Insulin and Insulin-like growth factor-1 can activate the phosphoinositide-3-kinase /Akt/FoxO1 pathway in T cells in vitro.

Hyper-glycemic food increases insulin-like growth factor 1 (IGF-1) and insulin signaling and regulates endocrine responses and thereby may modulate the course of acne. Inflammation and adaptive immune responses have a pivotal role in all stages of acne. Recent hypothesis suggests that hyperglycemic food reduces nuclear forkhead box-O1 (FoxO1) transcription factor and may eventually induces acne. The aim of our study was to investigate the role of IGF-1 and insulin on the phosphoinositide-3-kinase (PI3K)/Akt/FoxO1 pathway in human primary T cells and on the molecular functions of T cells in vitro. T cells were stimulated with 0.001 µM IGF-1 or 1 µM insulin +/- 20 µM PI3K inhibitor LY294002. T cells were also exposed to SZ95 sebocyte supernatants which were pre-stimulated with IGF-1 or insulin. We found that 0.001 µM IGF-1 and 1 µM insulin activate the PI3K pathway in T cells leading to up-regulation of p-Akt and p-FoxO1 at 15 and 30 minutes. Nuclear FoxO1 was decreased and FoxO transcriptional activity was reduced. 0.001 µM IGF-1 and 1 µM insulin increased T cell proliferation but have no significant effect on Toll-like receptor2/4 (TLR) expression. Interestingly, supernatants from IGF-1- or insulin-stimulated sebocytes activated the PI3K pathway in T cells but reduced T cell proliferation. Taken together, this study helps to support that high glycemic load diet may contribute to induce activation of the PI3K pathway and increase of proliferation in human primary T cells. Factors secreted by IGF-1- and insulin-stimulated sebocytes induce the PI3K pathway in T cells and reduce T cell proliferation, which probably can reflect a protective mechanism of the sebaceous gland basal cells.

Autoantibodies Against Glycoprotein 2 Isoforms in Pediatric Patients with Inflammatory Bowel Disease.

BACKGROUND: Anti-Glycoprotein 2 (GP2) antibodies are associated with a more complicated course of Crohn's disease (CD) in adults. Four different GP2 isoforms with different length and antibody-binding sites have been identified so far but not been explored in serological studies. We aimed to investigate the diagnostic utility of autoantibodies against all 4 isoforms of GP2 in an exclusively pediatric population for the first time. METHODS: We included 278 children and adolescents with inflammatory bowel disease: 164 with CD, 114 with ulcerative colitis, 83 disease controls (acute gastrointestinal infection, nonspecific gastrointestinal functional disorders), and 219 healthy controls. Sera were tested for anti-GP2 antibodies using 4 different isoforms of GP2 for anti-Saccharomyces cerevisiae antibodies, antineutrophil cytoplasmic antibodies, and pancreatic antibodies. RESULTS: Anti-GP2 antibodies were significantly more prevalent in patients with CD than in ulcerative colitis and controls. We found a sensitivity of 38% (with a specificity of 95%) for anti-GP2 IgG against isoform 4 in CD. Anti-GP2 IgA against isoform 1 and anti-GP2 IgG against isoform 4 possessed the best diagnostic values for identification of CD. For the differentiation of CD from ulcerative colitis anti-GP2 IgG against isoforms 3 and 4 proved to be most accurate markers. Anti-GP2 antibodies were associated with a more complicated disease behavior and bowel surgery in CD. In a subgroup of patients with CD, anti-GP2 IgG against isoform 4 proved to be a relatively stable marker over time independent of disease activity. CONCLUSIONS: Anti-GP2 antibodies against different isoforms are specific markers for CD and for different phenotypes in pediatric inflammatory bowel disease.

Activated protein C protects from GvHD via PAR2/PAR3 signalling in regulatory T-cells.

Graft-vs.-host disease (GvHD) is a major complication of allogenic hematopoietic stem-cell(HSC) transplantation. GvHD is associated with loss of endothelial thrombomodulin, but the relevance of this for the adaptive immune response to transplanted HSCs remains unknown. Here we show that the protease-activated protein C (aPC), which is generated by thrombomodulin, ameliorates GvHD aPC restricts allogenic T-cell activation via the protease activated receptor (PAR)2/PAR3 heterodimer on regulatory T-cells (Tregs, CD4+FOXP3+). Preincubation of pan T-cells with aPC prior to transplantation increases the frequency of Tregs and protects from GvHD. Preincubation of human T-cells (HLA-DR4-CD4+) with aPC prior to transplantation into humanized (NSG-AB°DR4) mice ameliorates graft-vs.-host disease. The protective effect of aPC on GvHD does not compromise the graft vs. leukaemia effect in two independent tumor cell models. Ex vivo preincubation of T-cells with aPC, aPC-based therapies, or targeting PAR2/PAR3 on T-cells may provide a safe and effective approach to mitigate GvHD.Graft-vs.-host disease is a complication of allogenic hematopoietic stem cell transplantation, and is associated with endothelial dysfunction. Here the authors show that activated protein C signals via PAR2/PAR3 to expand Treg cells, mitigating the disease in mice.

Transdifferentiation of mesenchymal stem cells into Schwann cell-like myelinating cells.

Bone marrow stromal cells (MSC) are multipotent stem cells that differentiate into cells of the mesodermal lineage. Although adult, their differentiation potential is remarkable, and they are able to transdifferentiate. Transdifferentiated cultivated rat MSC (tMSC) changed morphologically into cells resembling typical spindle-shaped Schwann cells (SC) with enhanced expression of LNGF receptor, Krox-20, CD104 and S100beta protein and decreased expression of bone morphogenetic protein receptor-1A compared to untreated rat MSC (rMSC). Transdifferentiation was reversible and repeatable. To evaluate the myelinating capacity, rMSC, tMSC, or SC cultured from male rats were grafted into an autologous muscle conduit bridging a 2-cm gap in the female rat sciatic nerve. The presence of the male-specific SRY gene (as revealed by PCR analysis) and S100 immunoreactivity of pre-labeled tMSC confirmed the presence of the implanted cells in the grafts. Three weeks after grafting, an appropriate regeneration was noted in the SC and in the tMSC groups, while regeneration in the rMSC group and in the control group without any cells was impaired. In contrast to SC, in some cases, single tMSC were able to myelinate more than one axon. Our findings demonstrate that it may be possible to differentiate MSC into therapeutically useful cells for clinical applications.