Identification of amino acid residues of the NR2A subunit that control glutamate potency in recombinant NR1/NR2A NMDA receptors

The NMDA type of ligand-gated glutamate receptor requires the presence of both glutamate and glycine for gating. These receptors are hetero-oligomers of NR1 and NR2 subunits. Previously it was thought that the binding sites for glycine and glutamate were formed by residues on the NR1 subunit. Indeed, it has been shown that the effects of glycine are controlled by residues on the NR1 subunit, and a “Venus flytrap” model for the glycine binding site has been suggested by analogy with bacterial periplasmic amino acid binding proteins. By analysis of 10 mutant NMDA receptors, we now show that residues on the NR2A subunit control glutamate potency in recombinant NR1/NR2A receptors, without affecting glycine potency. Furthermore, we provide evidence that, at least for some mutated residues, the reduced potency of glutamate cannot be explained by alteration of gating but has to be caused primarily by impairing the binding of the agonist to the resting state of the receptor. One NR2A mutant, NR2A(T671A), had anEC50for glutamate 1000-fold greater than wild type and a 255-fold reduced affinity for APV, yet it had single-channel openings very similar to those of wild type. Therefore we propose that the glutamate binding site is located on NR2 subunits and (taking our data together with previous work) is not on the NR1 subunit. Our data further imply that each NMDA receptor subunit possesses a binding site for an agonist (glutamate or glycine).</jats:p

A prospective evaluation of the predictive value of faecal calprotectin in quiescent Crohn’s disease

Background: The faecal calprotectin (FC) test is a non-invasive marker for gastrointestinal inflammation. Aim: To determine whether higher FC levels in individuals with quiescent Crohn’s disease are associated with clinical relapse over the ensuing 12 months.&lt;p&gt;&lt;/p&gt; Methods: A single centre prospective study was undertaken in Crohn's disease patients in clinical remission attending for routine review. The receiver operating characteristic (ROC) curve for the primary endpoint of clinical relapse by 12 months, based on FC at baseline, was calculated. Kaplan-Meier curves of time to relapse were based on the resulting optimal FC cutoff for predicting relapse.&lt;p&gt;&lt;/p&gt; Results: Of 97 patients recruited, 92 were either followed up for 12 months without relapsing, or reached the primary endpoint within that period. Of these, 10 (11%) had relapsed by 12 months. The median FC was lower for non-relapsers, 96µg/g (IQR 39-237), than for relapsers, 414µg/g (IQR 259-590), (p=0.005). The area under the ROC curve to predict relapse using FC was 77.4%. An optimal cutoff FC value of 240µg/g to predict relapse of quiescent Crohn’s had sensitivity of 80.0% and specificity of 74.4%. Negative predictive value was 96.8% and positive predictive value was 27.6%. FC≥240μg/g was associated with likelihood of relapse 5.7 (95% CI 1.9-17.3) times higher within 2.3 years than lower values (p=0.002).&lt;p&gt;&lt;/p&gt; Conclusions: In this prospective dataset, FC appears to be a useful, non-invasive tool to help identify quiescent Crohn’s disease patients at a low risk of relapse over the ensuing 12 months. FC of 240µg/g was the optimal cutoff in this cohort.&lt;p&gt;&lt;/p&gt

Prevalence of extraintestinal manifestations in paediatric patients with Inflammatory Bowel Disease : results from the Swiss IBD Cohort Study

Background: There is a paucity of data from large cohort studies on the prevalence and type of extraintestinal manifestations in pediatric patients with Crohn's disease (CD) and ulcerative colitis (UC). We aimed to assess the prevalence and type of EIM in pediatric patients with inflammatory bowel disease (IBD). Methods: Data from patients enrolled in the Pediatric Swiss IBD Cohort Study (P-SIBDCS) were analyzed. Since 2008 the P-SIBDCS collects data on patients aged 2-17 from hospitals and private practices across Switzerland. Results of continuous data are reported as median and interquartile range

Close follow-up is associated with fewer stricture formation and results in earlier detection of histological relapse in the long-term management of eosinophilic esophagitis.

BACKGROUND AND AIMS No recommendations exist regarding optimal follow-up schedule in patients with eosinophilic esophagitis (EoE) under maintenance treatment. METHODS We retrospectively evaluated a long-term surveillance concept at the Swiss EoE clinic, where clinical, endoscopic and histological disease activity is assessed annually regardless of EoE symptoms. Data on 159 adult patients under maintenance steroid treatment with available follow-up were analyzed. Patients were classified as having close (duration between visits <18 months) or non-close follow-up (≥18 months). RESULTS We analyzed a total of 309 follow-up visits of 159 patients (123 males, age at diagnosis 38.9 ± 15.4 years). 157 (51%) visits were within a close follow-up schedule (median duration between visits of 1.0 years (interquartile range (IQR) 0.9-1.2)), while 152 visits (49%) were not (median duration between visits 2.9 years (IQR 2.0-4.1)). There was no difference regarding ongoing clinical, endoscopic, and histological disease activity, and adherence to prescribed steroid treatment between the two groups. However, stricture formation was significantly less frequently observed at visits within a close follow-up schedule (22.9 vs. 33.6%, p = 0.038). Absence of close follow-up was a significant risk factor for stricture development in a multivariate regression model. Patients who achieved histological remission and were followed within a close-follow-up schedule had significantly earlier detection of histological relapse compared to patients not within such close follow-up. CONCLUSION Close follow-up is associated with fewer stricture formation and appears to result in earlier detection of histological relapse in patients with eosinophilic esophagitis. We advocate for regular assessment of disease activity (every 12-18 months) in order to detect relapsing disease as early as possible, and therefore potentially minimize the risk for EoE complications

Impact of Diagnostic Delay on Disease Course in Pediatric- versus Adult-Onset Patients with Ulcerative Colitis: Data from the Swiss IBD Cohort

INTRODUCTION Given the lack of data, we aimed to assess the impact of the length of diagnostic delay on the natural history of ulcerative colitis (UC) in pediatric (diagnosed <18 years) and adult patients (diagnosed ≥18 years). METHODS Data from the Swiss Inflammatory Bowel Disease Cohort Study were analyzed. Diagnostic delay was defined as the interval between the first appearance of UC-related symptoms until diagnosis. Logistic regression modeling evaluated the appearance of the following complications in the long term according to the length of diagnostic delay: colonic dysplasia, colorectal cancer, UC-related hospitalization, colectomy, and extraintestinal manifestations (EIMs). RESULTS A total of 184 pediatric and 846 adult patients were included. The median diagnostic delay was 4 [IQR 2-7.5] months for the pediatric-onset group and 3 [IQR 2-10] months for the adult-onset group (p = 0.873). In both, pediatric- and adult-onset groups, the length of diagnostic delay at UC diagnosis was not associated with colectomy, UC-related hospitalization, colon dysplasia, and colorectal cancer. EIMs were significantly more prevalent at UC diagnosis in the adult-onset group with long diagnostic delay than in the adult-onset group with short diagnostic delay (p = 0.022). In the long term, the length of diagnostic delay was associated in the adult-onset group with colorectal dysplasia (p = 0.023), EIMs (p < 0.001), and more specifically arthritis/arthralgias (p < 0.001) and ankylosing spondylitis/sacroiliitis (p < 0.001). In the pediatric-onset UC group, the length of diagnostic delay in the long term was associated with arthritis/arthralgias (p = 0.017); however, it was not predictive for colectomy and UC-related hospitalization. CONCLUSIONS As colorectal cancer and EIMs are associated with considerable morbidity and costs, every effort should be made to reduce diagnostic delay in UC patients

Expression patterns of TNFα, MAdCAM1 and STAT3 in intestinal and skin manifestations of inflammatory bowel disease

Background: Pathogenesis of cutaneous extraintestinal manifestations (EIM) in inflammatory bowel disease (IBD) remains elusive. Efficacy of anti-TNF agents suggests TNF-dependent mechanisms. The role of other biologics such as anti-integrins or JAK-inhibitors is not yet clear. Methods: We performed immunohistochemistry for TNFα, NFκB, STAT1/STAT3, MAdCAM1, CD20/68, caspase 3/9, IFNγ, Hsp-27/70 on 240 intestinal (55 controls, 185 IBD) and 64 skin biopsies (11 controls, 18 Erythema nodosum (EN), 13 Pyoderma gangenosum (PG), 22 psoriasis). A semiquantitative score (0-100%) was used for evaluation. Results: TNFα was upregulated in intestinal biopsies from active Crohn`s disease (CD) vs. controls (36.2 vs. 12.1, p<0.001), but not ulcerative colitis (UC: 17.9). NFκB however was upregulated in intestinal biopsies from both active CD and UC (43.2 and 34.5 vs. 21.8, p<0.001 and p=0.017). TNFα and NFκB were overexpressed in skin biopsies from EN, PG and psoriasis. No MAdCAM1 overexpression was seen in skin tissues, while it was upregulated in active UC vs. controls (57.5 vs. 35.4, p=0.003). STAT3 was overexpressed in the intestinal mucosa of active and non-active IBD, while a similar upregulation was seen in skin biopsies from EN (84.7 vs. 22.3, p<0.001) and PG (60.5 vs. 22.3, p=0.011), but not in psoriasis. Caspase 3 and CD68 overexpression in skin biopsies distinguished EN/PG from psoriasis and controls. Conclusions: Upregulation of TNFα/NFκB in EN and PG is compatible with the efficacy of anti-TNF in EIM management. Data on overexpressed STAT3, but not MAdCAM1 support a rationale for JAK-inhibitors in EN and PG, while questioning the role of vedolizumab

Low serum zinc levels predict presence of depression symptoms, but not overall disease outcome, regardless of ATG16L1 genotype in Crohn's disease patients.

Zinc deficiency (ZD) in Crohn's disease (CD) is considered a frequent finding and may exacerbate CD activity. ZD is associated with depression in non-CD patients. We aimed to assess the prevalence of ZD in CD patients in clinical remission, its association with mood disturbances and to analyze a potential impact on future disease course. Zinc levels from CD patients in clinical remission at baseline and an uncomplicated disease course within the next 3 years ( &lt;i&gt;n&lt;/i&gt; = 47) were compared with those from patients developing complications ( &lt;i&gt;n&lt;/i&gt; = 50). Baseline symptoms of depression and anxiety were measured with the Hospital Anxiety and Depression scale. Mean zinc level in the 97 patients (40.4 ± 15.7 years, 44.3% males) was 18.0 ± 4.7 μmol/l. While no ZD (&lt;11 μmol/l) was observed, we found low zinc levels (&lt;15.1 μmol/l) in 28 patients (28.9%). Males had higher zinc levels compared with females (19.4 ± 5.7 &lt;i&gt;versus&lt;/i&gt; 16.8 ± 3.3, &lt;i&gt;p&lt;/i&gt; = 0.006). Patients with low zinc levels more often reported depression symptoms compared with patients with higher levels (27.3 &lt;i&gt;versus&lt;/i&gt; 9.4%, &lt;i&gt;p&lt;/i&gt; = 0.047). In a multivariate analysis, zinc levels were an independent negative predictor for depression symptoms [odds ratio (OR) 0.727, 95% confidence interval (CI) 0.532-0.993, &lt;i&gt;p&lt;/i&gt; = 0.045]. Zinc levels of patients with a complicated disease course were not different from those of patients without (17.7 ± 4.3 &lt;i&gt;versus&lt;/i&gt; 18.3 ± 5.1, n.s.). Baseline zinc levels did not predict disease outcome regardless of ATG16L1 genotype. Low-normal zinc levels were an independent predictor for the presence of depression symptoms in CD patients. Zinc levels at baseline did not predict a complicated disease course, neither in CD patients overall, nor ATG16L1 &lt;sup&gt;T300A&lt;/sup&gt; carriers

Development of Grb2 SH2 Domain Signaling Antagonists: A Potential New Class of Antiproliferative Agents

Aberrant signaling through protein-tyrosine kinase (PTK)-dependent pathways is associated with several proliferative diseases. Accordingly, PTK inhibitors are being developed as new approaches for the treatment of certain cancers. Growth factor receptor bound protein 2 (Grb2) is an important downstream mediator of PTK signaling that serves obligatory roles in many pathogenic processes. One of the primary functions of Grb2 is to bind to specific phosphotyrosyl (pTyr)-containing sequences through its Src homology 2 (SH2) domain. Agents that bind to the Grb2 SH2 domain and prevent its normal function could disrupt associated PTK signaling and serve as alternatives to kinase-directed inhibitors. Starting from the X-ray crystal structure of a lead peptide bound to the Grb2 SH2 domain, this review will summarize important contributions to these efforts. The presentation will be thematically arranged according to the region of peptide modified, proceeding from the N-terminus to the C-terminus, with a special section devoted to aspects of conformational constraint