Quercetin Increases MUC2 and MUC5AC Gene Expression and Secretion in Intestinal Goblet Cell-Like LS174T via PLC/PKCα/ERK1-2 Pathway

The main dietary flavonoid quercetin, is known to preserve the integrity of gastrointestinal barrier and to have anti-inflammatory, anti-cancer, anti-fibrotic, and other beneficial properties. Many of the biological effects of quercetin appear to be associated to the modulation of cell signaling pathways, rather than to its antioxidant activity. In spite of the large number of data available on the molecular and cellular mechanisms by which quercetin exerts its biological effects, including protection of intestinal barrier function, there is a lack of data about the role of this substance on the expression and/or the secretion of mucins released by intestinal goblet cells. Here we investigated the effects of quercetin on the secretion and the gene expression of the main intestinal gel-forming mucins, MUC2 and MUC5AC, and the signaling mechanisms underlined, in human intestinal goblet cell-like LS174T. We found that quercetin increases intracellular Ca²⁺ levels and induces MUC2 and MUC5AC secretion in a Ca²⁺-dependent manner. Quercetin also induces mRNA levels of both secretory mucins. Quercetin stimulation of LS174T cells increases phosphorylation levels of extracellular signal regulated kinase (ERK)1-2 and protein kinase C (PKC) α and the induction of MUC2 and MUC5AC secretion and mRNA relies on phospholipase C (PLC), PKC, and ERK1-2 signaling pathways since the PLC inhibitor U73122, the PKC inhibitor bisindolylmaleimide (BIM) and the ERK1-2 pathway inhibitor PD98059, all revert the stimulatory effects of quercetin. We also demonstrated that the induction of mucin gene expression by quercetin is not limited to goblet cells. Indeed, quercetin induces mRNA levels of MUC2 and MUC5AC via PKCα/ERK1-2 pathway also in the human intestinal epithelial Caco-2 cells. These data highlight a novel mechanism thereby quercetin, regulating the secretory function of intestinal goblet cells and mucin levels in enterocytes may exert its protective effects on intestinal mucosal barrier.

Prognostic significance of thyroglobulin antibody epitopes in differentiated thyroid cancer

CONTEXT

Thyroglobulin antibodies (TgAbs) are surrogate markers of disease recurrence or persistence in differentiated thyroid cancer (DTC). However, the prognostic significance of TgAb heterogeneity in DTC has not been investigated.

OBJECTIVE

To evaluate the relationship between TgAb epitope specificities and clinical outcomes in DTC patients.

DESIGN

We studied 61 TgAb-positive patients with DTC, post-thyroidectomy and remnant ablation (7 males, 54 females; age-range 16-80 years, median follow-up duration 8.9 years). TgAb epitope reactivities were mapped using a panel of 10 thyroglobulin (Tg) monoclonal antibodies delineating six antigenic Tg clusters in competitive ELISA studies. Sera from 45 patients with Hashimoto's thyroiditis (HT) and 22 TgAb-positive healthy subjects served as autoimmune and healthy controls. Tg was measured by immunoradiometric assay (IRMA), electrochemiluminescence immunoassay (ECLIA), and RIA, while TgAbs was measured by ELISA and ECLIA methods.

RESULTS

Samples from 26 DTC patients showed TgAb epitope restriction similar to HT patients, while 35 patients exhibited nonspecific reactivity comparable to healthy controls. DTC patients with epitope restriction had higher rates of recurrent/persistent disease (81% vs 17%, P < .001), higher median TgAb concentration (887.0 vs 82.0 kIU/L; P < .001), and a higher prevalence of thyroid lymphocytic infiltration (71.4% vs 26.8%; P < .001) compared to patients with nonspecific reactivity. Samples with epitope restriction also had a lower median Tg-IRMA/RIA ratio (3.0% vs 36.0%; P < .001) denoting greater degrees of Tg assay interference.

CONCLUSIONS

TgAb epitope restriction is associated with a less favorable prognosis than nonspecific reactivity in DTC patients. TgAb epitope specificities may have prognostic value in DTC.

The PEA15 gene is overexpressed and related to insulin resistance in healthy first-degree relatives of patients with type 2 diabetes

AIMS/HYPOTHESIS

Overexpression of the gene encoding phosphoprotein enriched in astrocytes 15 (PEA15), also known as phosphoprotein enriched in diabetes (PED), causes insulin resistance and diabetes in transgenic mice and has been observed in type 2 diabetic individuals. The aim of this study was to investigate whether PEA15 overexpression occurs in individuals at high risk of diabetes and whether it is associated with specific type 2 diabetes subphenotypes.

SUBJECTS AND METHODS

We analysed PEA15 expression in euglycaemic first-degree relatives (FDR) of type 2 diabetic subjects.

RESULTS

The expression of PEA15 in peripheral blood leucocytes (PBLs) paralleled that in fat and skeletal muscle tissues. In PBLs from the FDR, PEA15 expression was two-fold higher than in euglycaemic individuals with no family history of diabetes (control subjects), both at the protein and the mRNA level (p < 0.001). The expression of PEA15 was comparable in FDR and type 2 diabetic subjects and in each group close to one-third of the subjects expressed PEA15 levels more than 2 SD higher than the mean of control subjects. Subjects with IFG with at least one type 2 diabetes-affected FDR also overexpressed PEA15 (p < 0.05). In all the groups analysed, PEA15 expression was independent of sex and unrelated to age, BMI, waist circumference, systolic and diastolic BP, and fasting cholesterol, triacylglycerol and glucose levels. However, in euglycaemic FDR of type 2 diabetic subjects, PEA15 expression was inversely correlated with insulin sensitivity (r = -557, p = 0.01).

CONCLUSIONS/INTERPRETATION

We conclude that PEA15 overexpression represents a common defect in FDR of patients with type 2 diabetes and is correlated with reduced insulin sensitivity in these individuals.

[Methimazole versus methimazole and diphosphonates in hyperthyroid and osteoporotic patients]

AIM

It is well-know that hyperthyroidism is one of the key causes of secondary osteoporosis. High values of thyroid hormones increase the bone mineral turnover speed by promoting osteoclastic and osteoblastic activities. The aim of our study is to evaluate the increase of bone mineral density (BMD) in osteoporotic and hyperthyroid patients treated with only antithyroid drugs versus patients treated with antithyroid drugs and diphosphonates.

METHODS

Twenty-six elderly male patients, 65-75 years, were selected. In all these patients, thyroid function (FT3, FT4, TSH, Tg, AbTg, AbTPO) was evaluated at baseline and after 6 and 12 months from the start of medical treatment; the following were evaluated: BMD, calcium serum, phosphorus serum, alkaline phosphatase, PTH and 24 hours urinary calcium, phosphorus and hydroxyprolin. Thirteen patients (group 1) were treated with antithyroid drugs (methimazole 5-20 mg/die/os) and diphosphonates (alendronate 10 mg/die/os). The control group of 13 patients (group 2) was treated with antithyroid drugs only.

RESULTS

After 6 months of treatment, the patients of group 1 showed a mean increase of 2.5% in lumbar spine BMD compared with a mean increase of 0.3% in group 2 (p<0.01). After 12 months, group 1 showed a mean increase of 6.2% in lumbar spine BMD, compared with a mean increase of 2% in group (p<0.001).

CONCLUSIONS

The combination of antithyroid and diphosphonates drugs appears to be more efficacious than antithyroid therapy alone for the treatment of osteoporosis in male hyperthyroid patients.