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In Crohn's disease, correlation between clinical assessment and disease activity at tissue level is weak. Our aim was to evaluate the value of serum calprotectin as a biomarker for Crohn's disease.The STORI trial patients (n=115) were studied at baseline, in clinical remission before infliximab withdrawal, or at the time of relapse after infliximab withdrawal. Forty healthy controls were also studied. Serum calprotectin level was measured by ELISA. Data were analyzed through correlation analyses, Kaplan Meier curves and Cox model, using available Crohn's Disease Activity Index (CDAI), Crohn's Disease Endoscopic Index of Severity (CDEIS), fecal calprotectin and C-reactive protein levels (hsCRP).Median serum calprotectin was 8892 ng/mL (range: 410-125,000 ng/mL) in Crohn disease patients as compared with 1318 ng/mL (range: 215.8-3770 ng/mL) in controls (P0.0001). Serum calprotectin was significantly higher for active disease (median=19,584 ng/mL) than for inactive disease (median=8353 ng/mL) (P0.0001). Serum calprotectin correlated with hsCRP (r=0.4092, P0.0001) and CDAI (r=0.4442, P0.0001), but not with CDEIS, on the contrary to fecal calprotectin (r=0.6458, 0.5515, 0.2577 with P0.0001, P0.0001, P=0.019 respectively). In multivariate analysis, serum calprotectin used as a discrete variable (threshold: 5675 ng/ml), appeared complementary to hsCRP (5 mg/l) and fecal calprotectin (250 μg/g) to predict relapse after infliximab withdrawal (P=0.0173, 0.0024 and 0.0002; HR: 3.191, 3.561 and 4.120).As a CD biomarker, serum calprotectin has a similar profile as hsCRP. It is also complementary to fecal calprotectin and hsCRP for prediction of relapse after infliximab withdrawal.

After fifteen years of use, the anti-TNF antibodies have become the corner stone of the treatment of moderate and severe Crohn's disease. The skill acquired over the years through experimental trials and clinical experience leads to increased therapeutic efficacy and minimized risks. These antibodies are introduced increasingly earlier in Crohn's disease as well as in a broader range of patients, aiming at changing the natural history of the diseases by avoiding the development of intestinal tissue damage and complications.

Clinical proteomics is a technical approach studying the entire proteome expressed by cells, tissues or organs. It describes the dynamics of cell regulation by detecting molecular events related to diseases development. Proteomic techniques focus mainly on identification of new biomarkers or new therapeutic targets. It is a multidisciplinary approach using medical, biological, bioanalytical and bioinformatics knowledges. A strong collaboration between these fields allowed SELDI-TOF-MS proteomics studies to be performed at the CHU and the University of Liège, in GIGA-Research facilities. The aim of these studies was driven along three main axes of research related to the identification of biomarkers specific to a studied pathology, to a common biological pathway and, finally, to a treatment response. This work was presented in the setting of the "Synthèse CHU 2009" meeting.

In the last few years, increased attention has been focused on enzymes produced by cold-adapted micro-organisms. It has emerged that psychrophilic enzymes represent an extremely powerful tool in both protein folding investigations and for biotechnological purposes. Such enzymes are characterised by an increased thermosensitivity and, most of them, by a higher catalytic efficiency at low and moderate temperatures, when compared to their mesophilic counterparts. The high thermosensitivity probably originates from an increased flexibility of either a selected area of the molecular edifice or the overall protein structure, providing enhanced abilities to undergo conformational changes during catalysis at low temperatures. Structure modelling and recent crystallographic data have allowed to elucidate the structural parameters that could be involved in this higher resilience. It was demonstrated that each psychrophilic enzyme adopts its own adaptive strategy. It appears, moreover, that there is a continuum in the strategy of protein adaptation to temperature, as the previously mentioned structural parameters are implicated in the stability of thermophilic proteins. Additional 3D crystal structures, site-directed and random mutagenesis experiments should now be undertaken to further investigate the stability-flexibility-activity relationship.