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D Franchimont

Publications and source records attributed to D Franchimont.

12 recordsLinked to original sources
PubMed1998

Cellular and molecular aspects of thymic T-cell education in neuroendocrine self principles. Implications for autoimmunity.

Thymic epithelial and nurse cells from different species express a repertoire of neuroendocrine polypeptide precursors. This repertoire exerts a dual role in T-lymphocyte selection according to their status either as cryptocrine signals or as neuroendocrine self-antigens of the peptide sequences that are processed from those precursors then presented to pre-T cells. Thymic neuroendocrine self-antigens correspond to peptide sequences highly conserved throughout evolution of their family. Though thymic MHC class I molecules are involved in the processing of thymic neuroendocrine self-antigens, preliminary data show that their presentation to pre-T cells is not allelically restricted. Thymic T-cell education in neuroendocrine families also implies that the structure of a given family may be presented to pre-T cells. Our studies have evidenced the homology between thymic neuroendocrine-related self-antigens and dominant T-cell epitopes of peripheral neuroendocrine signals (neuroendocrine autoantigens). The biochemical difference between neuroendocrine autoantigens and homologous thymic self-antigens might explain the opposite immune responses evoked by those two types of antigens (activation and memory induction vs. tolerogenic effect). Altogether, these studies support the therapeutic use of thymic neuroendocrine self-antigens in reprogramming the immunological self-tolerance that is broken in autoimmune endocrine diseases like insulin-dependent diabetes type I. As recently stated by P. M. Allen in an important review, the fate of developing T lymphocytes in the thymus is influenced by the numerous types of peptidic interactions within the thymic cellular environment. To define the precise nature of thymic cells and naturally occurring biochemical peptide signals involved in positive and negative selection of immature T cells has become a prominent objective for the future research efforts in thymic physiology. This paper will try to show how thymic neuroendocrine-related peptides synthesized and processed within the thymic microenvironment indeed can play a role both in the development of the peripheral T-cell repertoire and in the death of randomly rearranged, self-reactive T cells.

Animals↗
PubMed1998

Effects of dexamethasone on the profile of cytokine secretion in human whole blood cell cultures.

EXPERIMENTAL OBJECTIVES: The interaction between the endocrine and immune systems is a very intriguing area. Endogenous glucocorticoids, as end-effectors of the hypothalamo-pituitary-adrenal axis, inhibit the immune and inflammatory responses and are used as immunosuppressive drugs in many inflammatory, autoimmune and allergic diseases. The aims of this study were to investigate the effects of dexamethasone on the profile of cytokine secretion in whole blood cell cultures from healthy subjects and to analyse the gender-related sensitivity to dexamethasone on each cytokine secretion. RESULTS: There was a significant inhibition by dexamethasone (from 1 to 100 nM) on the secretion of monokines (IL-1beta, IL-6, IL-8 and TNF alpha) and lymphokines (IL-2, IL-4, IL-10 and IFN gamma), either after LPS or PHA stimulation (P < 0.01). Interleukin 4 and IL-10 were less inhibited than IFN gamma (P < 0.05 at 1 nM, P < 0.01 at 10 nM and P < 0.001 from 100 nM to 10 microM). No gender difference was observed in the rate of inhibition of the secretion of each cytokine. CONCLUSION: This study shows that the inhibition of cytokine secretion by dexamethasone is more marked on Th1-type cytokines than on Th2-type cytokines. These data support the idea that glucocorticoids may induce a shift from the Th1 to Th2 profile of cytokine secretion.

Adult↗
PubMed1998

Anticipation in familial Crohn's disease.

BACKGROUND: Offspring with a family history of Crohn's disease have an earlier age of onset than their parents. This might be due to genetic anticipation, characterised by earlier and/or more severe disease in subsequent generations. AIMS: To investigate the possibility of genetic anticipation in affected parent-child pairs with Crohn's disease from France and Belgium. PATIENTS AND METHODS: In a cohort of 160 multiply affected families with Crohn's disease, 57 parent-first affected child pairs were detected. Clinical characteristics (age at diagnosis, disease extent, and type) of both parents and children were registered and compared. RESULTS: Children were younger than their parents at diagnosis in 48/57 (84%) pairs. The median age at diagnosis was 16 years younger in children than in parents (p < 0.0001). However, the difference was related to the age at diagnosis in the parents and was not present in 12 parent-child pairs with an early age at diagnosis for the parents. In most cases, disease extent and type were not considered more severe in children than in parents. Parental sex affected neither age at diagnosis nor extent and type of disease in children. CONCLUSION: Patients in the second affected generation acquire their disease at an earlier time in life in some but not all familial cases of Crohn's disease. Several explanations including genetic anticipation and environmental factors might explain this phenomenon.

Adolescent↗
PubMed1997

Identification of neurotensin-related peptides in human thymic epithelial cell membranes and relationship with major histocompatibility complex class I molecules.

This study shows the expression at the cell surface of human thymic epithelial cells (TEC) of a neurotensin (NT)-like immunoreactivity. NT radio-immunoassay (RIA) revealed that cultured human TEC contain +/-5 ng immunoreactive (ir) NT/10(6) cells, of which 5% is associated with plasma cell membranes. HPLC analysis of NT-ir present in human TEC showed a major peak of NT-ir corresponding to NT1-13. NT-ir was not detected in the supernatant of human TEC cultures. Using an affinity column prepared with a anti-MHC class I monoclonal antibody, NT-ir-related peptides were retained on the column and eluted together with MHC class I-related proteins. According to the elution time on HPLC of these peptides, they correspond to intact NT1-13, as well as to smaller fragments of NT1-13.

Cell Membrane↗
PubMed1997

A high serum concentration of interleukin-6 is predictive of relapse in quiescent Crohn's disease.

BACKGROUND/AIMS: Relapses of Crohn's disease are difficult to predict. We assessed the value of serum level of interleukin-6, tumour necrosis factor alpha (TNF-alpha) and soluble TNF receptors as predictors of relapse in quiescent Crohn's disease. PATIENTS/METHODS: Thirty-six patients with inactive Crohn's disease, treated or not, were included. Various clinical and biological parameters, including interleukin-6, TNF-alpha and soluble TNF receptors serum levels were measured at inclusion in the study and the patients were followed clinically for 1 year. The relapse was defined as a Crohn's Disease Activity Index (CDAI) greater than 150 with an increase greater than 100 compared to the inclusion value. We analysed the ability of these parameters to predict relapse in parallel to clinical characteristics and other laboratory parameters. RESULTS: Among the 32 variables tested, interleukin-6 serum level had the greatest ability to predict the time-to-relapse, with 17-fold chance of relapse over a 1-year period for patients with an interleukin-6 serum level greater than 20 pg/ml than for patients with a lower level (P < 0.001). A high serum level of the soluble TNF receptors p55 and p75 also had significant predictive value, in contrast to TNF-alpha serum levels. An interleukin-6 serum level greater than 20 pg/ml and either an acid alpha-1-glycoprotein level greater than 1.1 g/l or a soluble interleukin-2 receptor serum level greater than 95 pM/l were risk factors selected by a stepwise multivariate analysis. In both models a good prognosis group was defined by the absence of the two risk factors, a bad prognostic group by the presence of the two risk factors and an intermediate in between. With both models, the good prognosis group included 17 patients who experienced no relapse over the 1-year follow-up, whereas all patients (seven with the first model and six with the second) in the bad prognosis group had a relapse during the follow-up. Looking specifically at two homogeneous subgroups including either naturally/5-aminosalicylic acid (5-ASA) quiescent or corticoid quiescent patients, a very good predictive value for interleukin-6 serum concentration was also found. CONCLUSION: Interleukin-6 serum level alone or in association with other biological parameters such as acid alpha-1-glycoprotein or the soluble interleukin-2 receptor serum level may be useful for predicting the course of the disease in patients with quiescent Crohn's disease.

Adolescent↗
PubMed1996

Decrease in systemic tolerance to fed ovalbumin in indomethacin-treated mice.

The oral administration of non-steroidal anti-inflammatory drugs (NSAID) to animals induces a quick increase in intestinal permeability and secondary inflammatory lesions of the intestine. The mechanisms leading to the inflammatory lesions are hypothetical. The increased intestinal permeability could allow a greater mucosal and systemic penetration of fed antigens and bacterial products leading to an abnormal mucosal and systemic immune and inflammatory response toward these materials. We examined the effect of oral dosing with indomethacin on ovalbumin serum levels and the systemic immune response to ovalbumin in mice fed with ovalbumin. The ovalbumin serum level was higher in indomethacin-treated mice and the increase was proportional to the dose of indomethacin. It was associated with epithelial and subepithelial lesions. Moreover, the systemic humoral and, to a lesser extent, the cellular tolerance were partially abrogated in the treated mice. These findings suggest that the oral administration of indomethacin in mice induces an increased passage of fed antigen through the intestinal epithelium associated with a decrease in systemic tolerance to this antigen. The reason for this decrease remains unclear. Besides a disequilibrium between systemic and mucosal immune responses, a loss of integrity of the intestinal epithelial cells and a direct immunomodulating effect of indomethacin may also be involved. This decrease in systemic tolerance to luminal antigen could be involved in the development of NSAID enteropathy.

Administration, Oral↗
PubMed1995

Systemic immune response after rectocolonic administration of ovalbumin in mice.

The aim of our study was to determine the effect of a rectocolonic preimmunization with ovalbumin on the systemic immune response induced by a subsequent subcutaneous injection of this antigen in Balb/c mice. One rectocolonic, but not intragastric, administration of 25 mg of ovalbumin induced a detectable increase in serum anti-ovalbumin antibody level. The level reached was however much lower than after subcutaneous injection. Both intragastric and rectocolonic immunization with ovalbumin induced specific systemic cellular tolerance. However, after rectocolonic, but not intragastric, preimmunization there was no systemic humoral tolerance to this antigen. These differences in systemic immune responses after rectocolonic or intragastric administration of ovalbumin could be due to different stimulation of the systemic immune system or to differences between the colonic and small bowel mucosal immune system, which remain to be elucidated.

Administration, Rectal↗
PubMed1993

[Current contribution of genetics in intestinal inflammatory diseases].

It is clear since many years that the liability to develop inflammatory bowel disease is influenced by genetic factors. Recent progresses in the field of genetic markers and genetic models bring the concept of genetic heterogeneity. This new concept leads us to try to classify different forms of inflammatory bowel disease and could have in the future an impact on the prevention, the follow up and the treatment of these diseases.

Adolescent↗
PubMedDate not supplied

Intestinal permeability in Crohn's disease.

We summarize the anatomical and physiological basis and the ways of measuring the intestinal permeability. We review the studies of the intestinal permeability in Crohn's disease. We analyse the involvement of an abnormal intestinal permeability in the pathogenesis of Crohn's disease, as a primary or secondary defect. We discuss the potential usefulness of the measure of intestinal permeability in Crohn's disease activity assessment, relapse prediction and efficacy of treatment.

Biomarkers↗
PubMedDate not supplied

Familial Crohn's disease: a study of 18 families.

UNLABELLED: The high frequency of familial Crohn's disease (CD) suggests a genetic predisposition. The most recent data from epidemiology and molecular biology are consistent with a multifactorial, polygenic inheritance with a possible genetic heterogeneity. The aim of our study was, first to compare familial and sporadic CD on the basis of the type and location of the disease, and age at diagnosis, and second, to evaluate among families, the concordance rate for the type and location of the disease. PATIENTS AND METHODS: 18 families with 2 (n = 16) and 3 (n = 2) affected first degree relatives were studied. They were compared to a population of 154 sporadic CD coming from the same gastroenterology unit. RESULTS: Age at diagnosis was the same in sporadic and familial CD. There was an increased frequency of ileal (p = 0.02), and fibro stenotic (p = 0.005) CD and a decreased frequency of colonic (p = 0.006) and inflammatory (p = 0.02) disease, in familial CD. There was a significant increase in concordance rate for fibrostenotic disease (p < 0.001) and a decrease for inflammatory disease (p < 0.01), among the families. The observed concordance rate for the location of the disease was not significantly different from the expected one. In conclusion, these data suggest that CD may be heterogenous and that different clinical patterns may be determined either by genetic or environmental factors.

Adult↗