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Biomedical subjects

Pierre Michetti

Publications and source records attributed to Pierre Michetti.

11 recordsLinked to original sources
PubMed2003

Intravenous hydrocortisone premedication reduces antibodies to infliximab in Crohn's disease: a randomized controlled trial.

BACKGROUND & AIMS: We assessed the relationship between antibodies to infliximab (ATI) and the loss of response postinfliximab, infusion reactions and, in a randomized trial, investigated whether intravenous hydrocortisone premedication can reduce ATI. METHODS: Initially, we prospectively evaluated clinical response, adverse events, and ATI levels in 53 consecutive patients with Crohn's disease who received 199 infliximab (5 mg/kg) infusions. Subsequently, 80 patients with Crohn's disease were randomized to intravenous hydrocortisone 200 mg or placebo immediately before their first and subsequent infliximab infusions. The primary endpoint was reduction in median ATI levels at week 16. Analysis was by intention to treat. RESULTS: Nineteen of our initial 53 patients (36%) developed ATI, including all 7 patients with serious infusion reactions (median ATI level, 19.6 microg/mL). Eleven of 15 patients (73%) who lost their initial response were ATI positive compared with none of 21 continuous responders, (8.9 vs. 0.7 microg/mL, P < 0.0001). Administering a second infusion within 8 weeks of the first (OR, 0.13; 95% CI, 0.03-0.5; P = 0.0007) or concurrent immunosuppressants (OR, 0.19; 95% CI, 0.04-1.03; P = 0.007) significantly reduced ATI formation. In the placebo-controlled trial, ATI levels were lower at week 16 among hydrocortisone-treated patients (1.6 vs. 3.4 microg/mL, P = 0.02), and 26% of hydrocortisone-treated patients developed ATI compared with 42% of placebo-treated patients, P = 0.06. CONCLUSIONS: Loss of initial response and infusion reactions post-infliximab is strongly related to ATI formation and level. Administering a second infusion within 8 weeks of the first and concurrent immunosuppressant therapy significantly reduce ATI formation. Intravenous hydrocortisone premedication significantly reduces ATI levels but does not eliminate ATI formation or infusion reactions.

Adult↗
PubMed2002

Safety and efficacy of E coli enterotoxin adjuvant for urease-based rectal immunization against Helicobacter pylori.

Low dose E. coli heat-labile enterotoxin (LT), delivered orally or enterically, has been used as an adjuvant for Helicobacter pylori (H. pylori) urease in healthy adults. In this study we aim to test the safety and adjuvant efficacy of LT delivered rectally together with recombinant H. pylori urease. Eighteen healthy adults without present or past H. pylori infection were enrolled in a double blind, randomized, ascending dose study to receive either urease (60 mg), or urease (60 mg) + LT (5 or 25 microg). The immunization preparation was administered per rectum on days 0, 14 and 28. Serum, stool and saliva anti-urease and anti-LT IgG and IgA antibodies (Abs) were measured and urease-specific and LT-specific antigen secreting cells (ASCs) were counted in peripheral blood at baseline and 7 (ASC counts) or 14 days (antibody levels) after each dosing. Peripheral blood lymphoproliferation assays were also performed at baseline and at the end of the study. Rectally delivered urease and LT were well tolerated. Among the 12 subjects assigned to urease+LT, 2 (16.7%) developed anti-urease IgG Abs, 1 (8.3%) developed anti-urease IgA Abs, and 3 (25%) showed urease-specific IgA(+) ASCs. Immune responses to LT were more vigorous, especially in subjects exposed to 5 microg LT. In the urease+ 5 microg LT group, anti-LT IgG and IgA Abs developed in 60 and 80% of the subjects, respectively, while LT-specific IgG(+) and IgA(+) ASCs were detected in all subjects. The magnitude of the anti-LT response was much higher than the response to urease. No IgA anti-urease or anti-LT Abs were detected in stool or saliva and lymphocyte proliferative responses to urease were unsatisfactory. In conclusion, rectal delivery of 5 microg LT is safe and induces vigorous systemic anti-LT immune responses. Further studies are needed to determine if LT can be an effective adjuvant for rectally delivered antigens.

Adjuvants, Immunologic↗
PubMed2002

Prospective comparison of MR enteroclysis with multidetector spiral-CT enteroclysis: interobserver agreement and sensitivity by means of "sign-by-sign" correlation.

Our objective was a prospective comparison of MR enteroclysis (MRE) with multidetector spiral-CT enteroclysis (MSCTE). Fifty patients with various suspected small bowel diseases were investigated by MSCTE and MRE. The MSCTE was performed using slices of 2.5 mm, immediately followed by MRE, obtaining T1- and T2-weighted sequences, including gadolinium-enhanced acquisition with fat saturation. Three radiologists independently evaluated MSCTE and MRE searching for 12 pathological signs. Interobserver agreement was calculated. Sensitivities and specificities resulted from comparison with pathological results ( n=29) and patient's clinical evolution ( n=21). Most pathological signs, such as bowel wall thickening (BWT), bowel wall enhancement (BWE) and lymphadenopathy (ADP), showed better interobserver agreement on MSCTE than on MRE (BWT: 0.65 vs 0.48; BWE: 0.51 vs 0.37; ADP: 0.52 vs 0.15). Sensitivity of MSCTE was higher than that of MRE in detecting BWT (88.9 vs 60%), BWE (78.6 vs 55.5%) and ADP (63.8 vs 14.3%). Wilcoxon signed-rank test revealed significantly better sensitivity of MSCTE than that of MRE for each observer ( p=0.028, p=0.046, p=0.028, respectively). Taking the given study design into account, MSCTE provides better sensitivity in detecting lesions of the small bowel than MRE, with higher interobserver agreement.

Artifacts↗
PubMed2002

Transepithelial transport of HIV-1 by M cells is receptor-mediated.

Human colon carcinoma Caco-2 cell monolayers undergo conversion into cells that share morphological and functional features of M cells when allowed to interact with B lymphocytes. A lymphotropic (X4) HIV-1 strain crosses M cell monolayers and infects underlying CD4(+) target cells. Transport requires both lactosyl cerebroside and CXCR4 receptors, which are expressed on the apical surface of Caco-2 and M cells. Antibodies specific for each receptor block transport. In contrast, a monotropic (R5) HIV-1 strain is unable to cross M cell monolayers and infect underlying monocytes, despite efficient transport of latex beads. Caco-2 and M cells do not express CCR5, but transfection of these cells with CCR5 cDNA restores transport of R5 virus, which demonstrates that HIV-1 transport across M cells is receptor-mediated. The follicle-associated epithelium covering human gut lymphoid follicles expresses CCR5, but not CXCR4, and lactosyl cerebroside, suggesting that HIV-1 infection may occur through M cells and enterocytes at these sites.

Biological Transport, Active↗
PubMed2002

Influence of Helicobacter pylori infection during atherogenesis in vivo in mice.

Inflammatory diseases may have a role in the pathogenesis of atherosclerosis. Several epidemiological and clinical studies have explored the possible association between Helicobacter pylori seropositivity, cardiovascular risk factors, and ischemic heart disease. The contradictory results of these studies have fueled a debate regarding the link between H pylori infection and atherogenesis. This study tested the hypothesis that H pylori infection might influence atherosclerosis in vivo in mice. Male wild-type C57/Bl6 mice and LDL-receptor deficient congenic mice were randomly assigned for infection with H pylori. All animals were fed a high-cholesterol diet (1.25%) for 6 or 12 weeks. At autopsy, we compared aortic atherosclerotic lesion formation and lipid deposition. H pylori infection influenced neither the progression of atherosclerotic lesions nor lipid deposition. Moreover, the cellularity of atherosclerotic lesions (macrophages and T cells) did not differ between mice infected or not infected with H pylori. This in vivo study performed in a mouse model of atherosclerosis revealed no indication that H pylori infection might contribute to the development of atherosclerotic lesion formation. The full text of this article is available at http://www.circresaha.org.

Animals↗
PubMed2002

Proteomic analysis of cytokine induced proteins in human intestinal epithelial cells: implications for inflammatory bowel diseases.

A role for cytokine regulated proteins in epithelial cells has been suggested in the pathogenesis of inflammatory bowel diseases (IBD). The aim of this study was to identify such cytokine regulated targets using a proteomic functional approach. Protein patterns from (35)S-radiolabeled homogenates of cultured colon epithelial cells were compared before and after exposure to interferon-gamma, interleukin-1beta and interleukin-6. Proteins were separated by two-dimensional polyacrylamide gel electrophoresis. Both autoradiographies and silver stained gels were analyzed. Proteins showing differential expression were identified by tryptic in-gel digestion and mass spectrometry. Metabolism related proteins were also investigated by Western blot analysis. Tryptophanyl-tRNA synthetase, indoleamine-2,3-dioxygenase, heterogeneous nuclear ribonucleoprotein JKTBP, interferon-induced 35kDa protein, proteasome subunit LMP2 and arginosuccinate synthetase were identified as cytokine modulated proteins in vitro. Using purified epithelial cells from patients, overexpression of indoleamine-2,3-dioxygenase, an enzyme involved in tryptophan metabolism, was confirmed in Crohn's disease as well as in ulcerative colitis, as compared to normal mucosa. No such difference was found in diverticulitis. Potentially, this observation opens new avenues in the treatment of IBD.

Argininosuccinate Synthase↗
PubMed2002

Endoscopic interventions for preneoplastic and neoplastic lesions: mucosectomy, argon plasma coagulation, and photodynamic therapy.

The classical treatment of neoplastic lesions is surgical resection. Improved detection of early lesions has offered new therapeutic strategies. Thus, for the last 20 years it has been increasingly attempted to undertake endoscopic resection of such tumors. While there is no doubt that morbidity and mortality are lower than after surgery, it was assumed that the long-term prognosis is not as good as with surgery. Surprisingly, however, the 5-year survival rates are excellent. Therefore, in local mucosal lesions of colon, stomach, and esophagus, endoscopic removal has become standard treatment. In Barrett's esophagus, the treatment modality it is still discussed controversially, despite encouraging results. Since we are yet not able to completely eliminate the premalignant specialized intestinal epithelium of the esophagus, it is still uncertain whether eradication of the malignant or dysplastic lesion is sufficient.

Barrett Esophagus↗
PubMed2002

[Ulcerative colitis].

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Anti-Inflammatory Agents, Non-Steroidal↗