Weight loss in obese prepubertal children: the influence of insulin resistance.

BACKGROUND: Insulin resistance (IR), a link of paramount importance between obesity and cardiovascular/metabolic complications, seems to be implicated in weight changes. OBJECTIVE: To determine whether IR could influence weight status during a 1-year intervention program in obese prepubertal children. METHODS: Forty-four children with IR (IR group) and 42 children without IR (NIR group) were enrolled. Body mass index standard deviation score (BMI-SDS), waist circumference (WC), and homeostasis model assessment (HOMA-IR) were evaluated. RESULTS: NIR children showed a significant reduction of BMI-SDS and WC at final assessment (p = 0.009 and p = 0.001, respectively), whereas IR children presented unchanged values. HOMA-IR decreased after intervention in the NIR group (p = 0.0008), but was exacerbated in IR children (p = 0.004). A positive and significant association between HOMA-IR at baseline and BMI at follow-up was found (B ± SE = 0.87 ± 0.24, p = 0.001). HOMA-IR at baseline was also significantly associated with WC at follow-up (B ± SE = 2.12 ± 0.69, p = 0.003). CONCLUSIONS: IR seems to influence adiposity changes in obese prepubertal children. Further longitudinal studies are needed to verify the relationship between IR and weight loss during childhood.

A novel insulin-like growth factor (IGF)-independent role for IGF binding protein-3 in mesenchymal chondroprogenitor cell apoptosis.

Chondrogenesis results from the condensation of mesenchymal chondroprogenitor cells (MCC) that proliferate and differentiate into chondrocytes. We have previously shown that IGF binding protein (IGFBP)-3 has an IGF-independent antiproliferative effect in MCC. The current study evaluates the IGF-independent apoptotic effect of IGFBP-3 on MCC to modulate chondrocyte differentiation. We employed the RCJ3.1C5.18 chondrogenic cell line, which in culture progresses from MCC to differentiated chondrocytes; cells do not express IGFs or IGFBP-3. We also used IGFBP-3 mutants with decreased (I56 substituted to G56; L80 and L81 to G80G81) or abolished binding for IGFs (I56, L80, and L81 to G56G80G81). MCC transfected with IGFBP-3 detached, changed their phenotype, and underwent apoptosis. A maximal IGFBP-3 apoptotic effect was observed 24 h after transfection (463 +/- 73% of controls; P < 0.001). Remarkably, IGFBP-3 mutants had similar effects, demonstrating that the IGFBP-3 apoptotic action was clearly IGF independent. In addition, treatment with IGFBP-3 in serum-free conditions resulted in a significant increase of apoptosis (173 +/- 23% of controls; P < 0.05). Moreover, this apoptotic effect was selective for MCC, resulting in a selective reduction of chondrocytic nodules and a significant decrease in type II collagen expression and proteoglycan synthesis. In summary, we have identified a novel IGF-independent role for IGFBP-3 in the modulation of chondrocyte differentiation.

Disappearance of gastric mucosa-associated lymphoid tissue in hepatitis C virus-positive patients after anti-hepatitis C virus therapy.

OBJECTIVE: Mucosa-associated lymphoid tissue, which has a follicular structure closely resembling Peyer patches, is absent in the normal gastric mucosa, but it can develop in several chronic conditions. Since we recently detected hepatitis C virus-RNA in gastric mucosa-associated lymphoid tissue of patients with chronic hepatitis C, we tried to treat hepatitis C virus infection to evaluate the effect of antiviral therapy on gastric mucosa-associated lymphoid tissue. METHODS: Eighteen patients (12 men and 6 women; mean age: 52 years, range: 33-71 years) affected by chronic hepatitis C virus and with gastric mucosa-associated lymphoid tissue were enrolled. We enrolled only patients hepatitis C virus-positive, mucosa-associated lymphoid tissue-positive, and Helicobacter pylori-negative (8 patients) or hepatitis C virus-positive patients in whom anti-H. pylori therapy did not obtain disappearance of gastric mucosa-associated lymphoid tissue (10 patients). Hepatitis C virus was evaluated by hepatic biopsy with histologic evaluation and serologic examination; Gastric mucosa-associated lymphoid tissue was scored using Wotherspoon score. All patients were treated with recombinant leukocyte interferon-alpha-2b plus oral ribavirin for 6 months. The hepatitis C virus RNA was assayed at entry and at 3 months after stopping treatment. Virologic response was defined as undetectable levels of serum hepatitis C virus RNA 3 months after stopping treatment; esophagogastroduodenoscopy was repeated at this time to evaluate the effect of anti-hepatitis C virus therapy on acquired gastric mucosa-associated lymphoid tissue. RESULTS: Two (11.11%) patients were withdrawn from the study. Hepatitis C virus cure was obtained in 11/16 patients (68.75%), and in all of them we obtained disappearance of gastric mucosa-associated lymphoid tissue (P < 0.01). Hepatitis C virus infection persisted, but with very lower levels, in 5 of 16 patients (31.25%): in 3 patients gastric mucosa-associated lymphoid tissue persisted (but in 2 it decreased from grade 3 to grade 2), while in 2 it disappeared. CONCLUSIONS: We showed clearly that there is a strict correlation between hepatitis C virus infection and acquired MALT, obtaining the disappearance of this acquired immunologic acquired gastric tissue curing hepatitis C virus infection. However, further studies are needed to clarify there is the same correlation between hepatitis C virus infection and gastric mucosa-associated lymphoid tissue lymphomas in hepatitis C virus-positive patients.

Detection of HCV RNA in gastric mucosa-associated lymphoid tissue by in situ hybridization: evidence of a new extrahepatic localization of HCV with increased risk of gastric malt lymphoma.

OBJECTIVES: Mucosa-associated lymphoid tissue (MALT) is absent in the normal gastric mucosa but it can develop in several conditions, such as Helicobacter pylori infection. A certain correlation between hepatitis C virus (HCV) infection and low grade MALT lymphomas has recently been reported. The aim of this study was to investigate the presence of HCV RNA in acquired gastric MALT of HCV-infected patients using the in situ hybridization technique. METHODS: Twenty-five patients (16 male and nine female, average age = 56.6 yr [range = 33-75]) affected by chronic HCV hepatitis and with gastric MALT were studied. Giemsa stain and the rapid urease test were also used to evaluate the presence of H. pylori. A polymerase chain reaction product corresponding to the complete 5' noncoding region of the HCV genome was cloned directly in the pCR 1000 vector on gastric biopsies with acquired MALT. RESULTS: Twenty patients showed grade 2 gastric MALT and five showed grade 3, and H. pylori's presence was detected in 18 of 25 patients (72%). Using in situ hybridization, we detected HCV RNA in gastric acquired MALT of seven of 25 patients (28%): five showed grade 2 gastric MALT (two of these were H. pylori negative and the other three were positive), whereas two patients showed grade 3 gastric MALT (without H. pylori infection). CONCLUSIONS: This study shows that HCV not only may colonize gastric MALT but also may permit the development of a grade of acquired MALT, which may represent the first step toward a MALT lymphoma. However, further studies are needed to demonstrate the antigenic role of HCV in the progression of acquired MALT into MALT lymphoma.

Defective lysosomal targeting of activated fibroblast growth factor receptor 3 in achondroplasia.

Mutations of fibroblast growth factor receptor 3 (FGFR3) are responsible for achondroplasia (ACH) and related dwarfing conditions in humans. The pathogenesis involves constitutive activation of FGFR3, which inhibits proliferation and differentiation of growth plate chondrocytes. Here we report that activating mutations in FGFR3 increase the stability of the receptor. Our results suggest that the mutations disrupt c-Cbl-mediated ubiquitination that serves as a targeting signal for lysosomal degradation and termination of receptor signaling. The defect allows diversion of actively signaling receptors from lysosomes to a recycling pathway where their survival is prolonged, and, as a result, their signaling capacity is increased. The lysosomal targeting defect is additive to other mechanisms proposed to explain the pathogenesis of ACH.

Identification of STAT-1 as a molecular target of IGFBP-3 in the process of chondrogenesis.

The chondrogenesis process requires the ordered proliferation and differentiation of chondrocytes. Insulin-like growth factor-binding protein (IGFBP)-3, well characterized as the carrier of insulin-like growth factor (IGF), has been reported to have intrinsic bioactivity that is independent of IGF binding. The mechanisms involved in this IGF-independent action are still unclear. Using the RCJ3.1C5.18 chondrogenic cells, which in culture progresses from undifferentiated to terminally differentiated chondrocytes, we have shown previously that IGFBP-3 has an IGF-independent, antiproliferative effect in undifferentiated and early differentiated but not in terminally differentiated chondrocytes. In the present study, cDNA microarray analysis was used to screen for genes: 1) that were regulated by IGFBP-3 in early but not in terminally differentiated chondrocytes; 2) that were regulated specifically by IGFBP-3, but not by IGF-I; and 3) whose regulation was abolished by coincubation of IGFBP-3 with IGF-I. Signal transducer and activator of transcription (STAT)-1 was the gene that, fulfilling the screening criteria, exhibited the greatest up-regulation by IGFBP-3 (>40-fold). STAT-1 gene up-regulation was confirmed by Northern analysis of cells treated with IGFBP-3 or transfected with an IGFBP-3 expression vector. Remarkably, similar results were obtained when cells were transfected with an IGFBP-3 mutant unable to bind IGFs, definitively demonstrating the IGF-independent action of IGFBP-3. Consistent with the up-regulation of STAT-1 mRNA, IGFBP-3 also increased STAT-1 protein expression. Furthermore, both IGFBP-3 and the IGFBP-3 mutant induced STAT-1 phosphorylation and its nuclear localization. An antisense STAT-1 oligonucleotide abolished the IGF-independent cell apoptosis induced by IGFBP-3. We have demonstrated that STAT-1 is a major intracellular signaling and transcriptional target of the IGF-independent apoptotic effect of IGFBP-3 in chondrogenesis.