Michel Peuchmaur

Inflammatory alterations in mesenteric adipose tissue in Crohn's disease

BACKGROUND & AIMS Abnormalities of fat in the mesentery including adipose tissue hypertrophy and fat wrapping have been long recognized on surgical specimens as characteristic features of Crohns disease. However, the importance, origin, and significance of the mesenteric fat hypertrophy in this chronic inflammatory disease are unknown. Peroxisome proliferator-activated receptor gamma (PPARgamma) is a crucial factor involved in the homeostasis of adipose tissue, a major source of biologically active mediators. METHODS Intra-abdominal fat accumulation was quantified using a magnetic resonance imaging method in patients with Crohns disease and controls. PPARgamma and inflammatory cytokines synthesized by mesenteric adipose tissues were assessed by quantitative polymerase chain reaction, in situ hybridization, and immunohistochemistry. RESULTS In vivo, patients with Crohns disease have an important accumulation of intra-abdominal fat. This mesenteric obesity, present from the onset of the disease, is associated with overexpression of PPARgamma and tumor necrosis factor (TNF)-alpha, synthesized, at least in part, by adipocytes. CONCLUSIONS These results suggest that confined increased PPARgamma mesenteric concentrations could lead to the mesenteric fat hypertrophy, which could actively participate through the synthesis of TNF-alpha in the inflammatory response.

Early development of polycystic kidney disease in transgenic mice expressing an activated mutant of the β-catenin gene

Autosomal dominant polycystic kidney disease (ADPKD) is common and is a major cause of renal failure. Although the genetics of ADPKD are well known and have led to the discovery of polycystins, a new protein family, the pathogenesis of the disease remains largely unknown. Recent studies have indicated that the β-catenin signaling pathway is one of the targets of the transduction pathway controlled by the polycystins. We have generated transgenic mice that overproduce an oncogenic form of β-catenin in the epithelial cells of the kidney. These mice developed severe polycystic lesions soon after birth that affected the glomeruli, proximal, distal tubules and collecting ducts. The phenotype of these mice mimicked the human ADPKD phenotype. Cyst formation was associated with an increase in cell proliferation and apoptosis. The cell proliferation and apoptotic indexes was increased 4–5-fold and 3–4-fold, respectively, in cystic tubules of the transgenic mice compared to that of littermate controls. Our findings provide experimental genetic evidence that activation of the Wnt/β-catenin signaling pathway causes polycystic kidney disease and support the view that dysregulation of the Wnt/β-catenin signaling is involved in its pathogenesis.

Recombinant Interferon Alfa-2b Combined with a Regimen Containing Doxorubicin in Patients with Advanced Follicular Lymphoma

BACKGROUND Interferon alfa and cytotoxic drugs have synergistic effects in patients with non-Hodgkins lymphoma. In 1986, we designed a clinical trial to evaluate the benefit of concomitant administration of recombinant interferon alfa with a regimen containing doxorubicin in patients with follicular non-Hodgkins lymphoma. METHODS The trial involved 242 patients with advanced low-grade follicular non-Hodgkins lymphoma selected on the basis of clinical, radiographic, and biologic criteria. All patients were treated with a regimen consisting of cyclophosphamide, doxorubicin, teniposide, and prednisone (CHVP), given monthly for six cycles and then every two months for one year. After randomization, 123 patients also received interferon alfa-2b at a dosage of 5 million units three times weekly for 18 months. The remaining 119 patients received chemotherapy alone. RESULTS As compared with the patients treated with CHVP only, the patients treated with CHVP plus interferon alfa had a higher overall rate of response (85 percent vs. 69 percent, P = 0.006), a longer median event-free survival (34 months vs. 19 months, P < 0.001), and a higher rate of survival at 3 years (86 percent vs. 69 percent, P = 0.02). Granulocyte toxicity was greater in the patients treated with CHVP plus interferon alfa than in those treated with CHVP alone. There were no treatment-related deaths. Interferon alfa had to be stopped because of toxic effects (fatigue and hepatitis) in 13 patients (11 percent). CONCLUSIONS The addition of interferon alfa to a regimen containing doxorubicin increased the rate of response, event-free survival, and overall survival in patients with advanced follicular non-Hodgkins lymphoma, without serious toxicity, although some patients were unable to tolerate the side effects.

Overall Genomic Pattern Is a Predictor of Outcome in Neuroblastoma

PURPOSE For a comprehensive overview of the genetic alterations of neuroblastoma, their association and clinical significance, we conducted a whole-genome DNA copy number analysis. PATIENTS AND METHODS A series of 493 neuroblastoma (NB) samples was investigated by array-based comparative genomic hybridization in two consecutive steps (224, then 269 patients). RESULTS Genomic analysis identified several types of profiles. Tumors presenting exclusively whole-chromosome copy number variations were associated with excellent survival. No disease-related death was observed in this group. In contrast, tumors with any type of segmental chromosome alterations characterized patients with a high risk of relapse. Patients with both numerical and segmental abnormalities clearly shared the higher risk of relapse of segmental-only patients. In a multivariate analysis, taking into account the genomic profile, but also previously described individual genetic and clinical markers with prognostic significance, the presence of segmental alterations with (HR, 7.3; 95% CI, 3.7 to 14.5; P < .001) or without MYCN amplification (HR, 4.5; 95% CI, 2.4 to 8.4; P < .001) was the strongest predictor of relapse; the other significant variables were age older than 18 months (HR, 1.8; 95% CI, 1.2 to 2.8; P = .004) and stage 4 (HR, 1.8; 95% CI, 1.2 to 2.7; P = .005). Finally, within tumors showing segmental alterations, stage 4, age, MYCN amplification, 1p and 11q deletions, and 1q gain were independent predictors of decreased overall survival. CONCLUSION The analysis of the overall genomic pattern, which probably unravels particular genomic instability mechanisms rather than the analysis of individual markers, is essential to predict relapse in NB patients. It adds critical prognostic information to conventional markers and should be included in future treatment stratification.

Revision of the International Neuroblastoma Pathology Classification: confirmation of favorable and unfavorable prognostic subsets in ganglioneuroblastoma, nodular.

Ganglioneuroblastoma, nodular (GNBn) comprises one of the categories of peripheral neuroblastic tumors. All tumors in this category, according to the original International Neuroblastoma Pathology Classification, are classified into an unfavorable histology group. Subsequently, it has been reported that GNBn can be divided into two prognostic subsets, a favorable subset (FS) and an unfavorable subset (US).

Card15 gene overexpression in mononuclear and epithelial cells of the inflamed Crohn’s disease colon

Background: Crohn’s disease is one of the principal human chronic inflammatory bowel diseases. Although its aetiology is still unknown, its complex pathogenesis has environmental, immunological, and genetic determinants. CARD15 is the first susceptibility gene implicated in the predisposition to Crohn’s disease and is known to be expressed only in monocytes. However, its expression in situ has not yet been studied. Aims: To analyse the tissue distribution of CARD15 and identify cells producing CARD15 in samples of colon from patients with Crohn’s disease and control subjects. Patients and methods: We analysed CARD15 gene expression in surgical specimens of colon from eight children with Crohn’s disease and nine controls by immunohistochemistry, in situ hybridisation, and reverse transcription-polymerase chain reaction (RT-PCR). Results: We showed that CARD15 was present only in the cytoplasm of macrophages in the normal colon. Increased CARD15 expression was detected in Crohn’s disease lesions. There were more CARD15 positive cells in Crohn’s disease lesions than in uninvolved areas. Both intestinal epithelial cells, macrophages, and their derivatives overproduced CARD15 in Crohn’s disease. To further assess CARD15 expression by intestinal epithelial cells, we performed RT-PCR on freshly isolated intestinal epithelial cells, and showed that these cells isolated from Crohn’s disease samples contained more CARD15 mRNA than intestinal epithelial cells from controls. Conclusions: We have demonstrated that colonic involvement in active Crohn’s disease is associated with increased CARD15 gene expression in both macrophages and intestinal epithelial cells. Therefore, this deregulation can affect the host-environment interaction and thus contribute to the pathogenesis of this disease.

Chimaeric anti‐CD20 monoclonal antibody (rituximab) in post‐transplant B‐lymphoproliferative disorder following stem cell transplantation in children

Post‐transplant lymphoproliferative disorder (PTLD) after haemopoietic stem cell transplantation is a serious complication that occurs in 8–22% of patients with high‐risk factors. We retrospectively investigated tolerance and efficacy of humanized anti‐CD20 monoclonal antibody (rituximab) as first‐line treatment in 12 children with B‐cell PTLD. At diagnosis, eight patients had tumoral involvement. The other four patients had fever, associated with raised Epstein–Barr virus (EBV) viral load and monoclonal gammopathy. Rituximab was given at the dose of 375 mg/m2 once a week by intravenous infusion (1–9 infusions). Only 1/48 infusions was associated with a grade 2 clinical adverse event. Eight out of 12 (66%) patients responded to the treatment and were in complete remission. All patients without tumoral involvement responded to the treatment. A rapid decrease in fever within 1 week was observed in all responders. Non‐responders did not show any clinical response during the first week. Tumoral involvement and immunodepression seemed to be more marked in non‐responders. Rituximab was an effective and well‐tolerated treatment of B‐cell PTLD. Early treatment before tumoral involvement seemed to be the most effective approach. Lack of rapid response should lead to intensification of PTLD treatment. Pre‐emptive treatment should be considered and evaluated in further longitudinal multicentre studies.

LOCALIZATION AND mRNA EXPRESSION OF CYP3A AND P-GLYCOPROTEIN IN HUMAN DUODENUM AS A FUNCTION OF AGE

Cytochromes P450 3A (CYP3A) and P-glycoprotein (P-gp) are mainly located in enterocytes and hepatocytes. The CYP3A/P-gp system contributes to the first-pass metabolism of many drugs, resulting in a limited bioavailability. During the neonatal period, a shift between CYP3A7, the fetal form, and CYP3A4 occurs in the liver, but data on the expression of the CYP3A/P-gp complex in the intestine are very limited. A total of 59 normal duodenal biopsies from white children aged 1 month to 17 years were studied. Localization of the proteins by immunohistochemistry analysis was performed using a polyclonal antibody, Nuage anti-CYP3A, and a monoclonal antibody, C494 anti-P-gp. The mRNA quantification was performed using highly specific real-time reverse transcription-polymerase chain reaction. Villin mRNA quantification was used for normalization. CYP3A protein was detected in all enterocytes in the samples from patients over 6 months of age, whereas it was not in younger samples. P-gp protein was expressed at the apical and upper lateral surfaces of the enterocytes. CYP3A isoforms and P-gp mRNA levels were highly variable. CYP3A4 and CYP3A5 mRNA levels were high during the first year of life and decreased with age, whereas CYP3A7 was detected at a low level in 64% of samples, whatever the age. P-gp mRNA expression level was also highly variable. Our results showed that neonates and infants had a significant expression of CYP3A and P-gp mRNA in the intestine, suggesting a different maturation profile of CYP3A and P-gp with age in the liver and the intestine.

Role of the Chemokine Stromal Cell-Derived Factor 1 in Autoantibody Production and Nephritis in Murine Lupus

In normal mice, stromal cell-derived factor 1 (SDF-1/CXCL12) promotes the migration, proliferation, and survival of peritoneal B1a (PerB1a) lymphocytes. Because these cells express a self-reactive repertoire and are expanded in New Zealand Black/New Zealand White (NZB/W) mice, we tested their response to SDF-1 in such mice. PerB1a lymphocytes from NZB/W mice were exceedingly sensitive to SDF-1. This greater sensitivity was due to the NZB genetic background, it was not observed for other B lymphocyte subpopulations, and it was modulated by IL-10. SDF-1 was produced constitutively in the peritoneal cavity and in the spleen. It was also produced by podocytes in the glomeruli of NZB/W mice with nephritis. The administration of antagonists of either SDF-1 or IL-10 early in life prevented the development of autoantibodies, nephritis, and death in NZB/W mice. Initiation of anti-SDF-1 mAb treatment later in life, in mice with established nephritis, inhibited autoantibody production, abolished proteinuria and Ig deposition, and reversed morphological changes in the kidneys. This treatment also counteracted B1a lymphocyte expansion and T lymphocyte activation. Therefore, PerB1a lymphocytes are abnormally sensitive to the combined action of SDF-1 and IL-10 in NZB/W mice, and SDF-1 is key in the development of autoimmunity in this murine model of lupus.

Reversible cardiac fibrosis and heart failure induced by conditional expression of an antisense mRNA of the mineralocorticoid receptor in cardiomyocytes

Cardiac failure is a common feature in the evolution of cardiac disease. Among the determinants of cardiac failure, the renin–angiotensin–aldosterone system has a central role, and antagonism of the mineralocorticoid receptor (MR) has been proposed as a therapeutic strategy. In this study, we questioned the role of the MR, not of aldosterone, on heart function, using an inducible and cardiac-specific transgenic mouse model. We have generated a conditional knock-down model by expressing solely in the heart an antisense mRNA directed against the murine MR, a transcription factor with unknown targets in cardiomyocytes. Within 2–3 mo, mice developed severe heart failure and cardiac fibrosis in the absence of hypertension or chronic hyperaldosteronism. Moreover, cardiac failure and fibrosis were fully reversible when MR antisense mRNA expression was subsequently suppressed.