What we know about the relationship between autoimmune thyroid diseases and gut microbiota: a perspective on the role of probiotics on pediatric endocrinology.

INTRODUCTION: Autoimmune diseases account for a cumulative overall prevalence of about 3-5% worldwide. Among them, autoimmune thyroid diseases (ATDs) are the most common and comprise two main entities: Hashimoto's thyroiditis (HT) and Graves-Basedow disease (GD). The pathogenesis of ATDs remains not fully elucidated, however the role of microbioma has been proposed. Gut microbiota exert an important influence on the intestinal barrier, nutrient metabolism and immune system development and functions. EVIDENCE ACQUISITION: In this review, we describe on the main features of ATDs in pediatrics, focusing on the reciprocal influence between gut microbiota, thyroid hormone metabolism and thyroid autoimmunity and consider the role of probiotics and other microbiota-targeted therapies in thyroid diseases with a perspective on pediatric endocrinology. EVIDENCE SYNTHESIS: Microbiome affects both endogenous and exogenous thyroid hormone metabolism and influences the absorption of minerals important to the thyroid function, which are iodine, selenium, zinc and iron. The alteration of the gut microbiota, with the consequent modifications in the barrier function and the increased gut permeability, seems involved in the development of autoimmune and chronic inflammatory diseases, including ATDs. The supplementation with probiotics showed beneficial effects on the thyroid hormone and thyroid function because this strategy could restore the intestinal eubiosis and the good strain microorganism proliferation. CONCLUSIONS: Even though the evidence about the interaction between microbiota and ATDs in pediatric patients is limited, the promising results obtained in the adult population, and in other autoimmune disorders affecting children, highlight the need of for further research in the pediatric field.

The Iodine Rush: Over- or Under-Iodination Risk in the Prophylactic Use of Iodine for Thyroid Blocking in the Event of a Nuclear Disaster.

Iodine is an essential element for the production of thyroid hormones (THs). Both deficient and excess iodine intakes may precipitate in adverse thyroidal events. Radioactive iodine (RI) is a common byproduct of nuclear fission processes. During nuclear emergencies RI may be released in a plume, or cloud, contaminating the environment. If inhaled or ingested, it may lead to internal radiation exposure and the uptake of RI mainly by the thyroid gland that absorbs stable iodine (SI) and RI in the same way. A dose of radiation delivered to the thyroid gland is a main risk factor for the thyroid cancer development. The SI prophylaxis helps prevent childhood thyroid cancer. The thyroid gland saturation with prophylactic SI ingestion, reduces the internal exposure of the thyroid by blocking the uptake of RI and inhibiting iodide organification. However, negative impact of inadequate SI intake must be considered. We provide an overview on the recommended iodine intake and the impact of SI and RI on thyroid in children and adolescents, discussing the benefits and adverse effects of the prophylactic SI for thyroid blocking during a nuclear accident. The use of SI for protection against RI may be recommended in cases of radiological or nuclear emergencies, moreover the administration of iodine for prophylactic purposes should be cautious. Benefits and risks should also be considered according to age. Adverse effects from iodine administration cannot be excluded. Precise indications are mandatory to use the iodine for thyroid blocking. Due to this natural adaption mechanism it's possible to tolerate large doses of iodine without clinical effects, however, a prolonged assumption of the iodine when not needed can be dangerous and may precipitate in severe thyroidal and non-thyroidal negative effects.

Pidotimod for the prevention of acute respiratory infections in healthy children entering into daycare: A double blind randomized placebo-controlled study.

Acute respiratory tract infections (ARTIs) are very common in pediatric age and reach a peak in the first 4 years of life, especially in children attending daycare. Pidotimod, a synthetic immunostimulant, may reduce the incidence of ARTIs in children with predisposing risk factors. Nevertheless studies on healthy children are presently lacking. We performed a double-blinded randomized placebo-controlled trial study to assess the efficacy of Pidotimod in a population of 3-year-old healthy children who just entered kindergarten. The main outcome was the incidence of respiratory infections in this population and the secondary outcome was the prescription of antibiotics. The study group consisted of healthy 3-year-old children who had not yet attended day-care centers. Patients were enrolled by a convenience sample of 17 family pediatricians (FP). Children were randomized to receive either Pidotimod 400 mg per os or placebo twice daily for the last 10 days of each month from October 2013 to April 2014. Any time a child presented to his/her FP with fever and ARTI was diagnosed, clinical and therapeutic data were collected. A total of 800 children were pre-screened, 733 did not meet the inclusion criteria and 10 refused to participate. Of the 67 eligible subjects, 57 were successfully enrolled within the study recruitment period and randomized to receive Pidotimod (n = 29) or placebo (n = 28). Eight children were lost to follow-up. In the final analysis were thus included 24 children who received Pidotimod and 25 who received placebo. The incidence rate ratio for respiratory infections was 0.78 (95%CI 0.53 to 1.15, p = 0.211) for Pidotimod vs. placebo. The corresponding risk ratio for antibiotic usage was 0.56 (95%CI 0.27 to 1.16, p = 0.120). In our trial, Pidotimod did not prove to be statistically superior to placebo for the prevention of ARTI in a population of healthy children who entered kindergarten. However, Pidotimod showed some potential as a means for reducing antibiotic usage in these children.

Nutrient intake in Italian infants and toddlers from North and South Italy: the Nutrintake 636 study.

We performed a cross-sectional study to compare the intake of energy, macronutrients, fiber, sodium and iron and the anthropometric status of infants and toddlers living in North (Milano) and South Italy (Catania). Nutrient intake was evaluated using a 7-day weighed food record. Out of 400 planned children aged 6 to 36 months, 390 (98%) were recruited, 189 in Milano and 201 in Catania. The mean (standard deviation) age was 17 (9) months in Milano and 17 (10) months in Catania. Anthropometry, energy intake and macronutrient intake were similar in Milano and Catania. However, iron intake was 27% lower and fiber intake 16% higher in Milano than in Catania. Despite normal anthropometry and energy intake, in the pooled sample there was a high intake of proteins, simple carbohydrates, saturated fats and sodium, and a low intake of iron and fiber compared to Italian reference values. This is the first study to report the macro- and micro-nutrient intake of children aged <12 months using the 7-day weighed food record and one of the very few studies that have employed such reference method in children from the general population.

Pidotimod: the past and the present.

At the end of 1990s, acute respiratory tract infections (ARTIs) were called the 'forgotten pandemic', with a clear dichotomy between developing and industrialised countries in mortality and morbidity, the main outcomes associated with ARTIs. This definition still applies 20 years later, when the introduction of new and safe antibiotics and vaccines has certainly contributed to controlling the most life-threatening ARTIs, but has not had a major impact on viral ARTIs in paediatric age. One functional approach to preventing and treating ARTIs is non-specifically increasing the immune response or enhancing the children's innate defence mechanisms. Different kinds of biologically active substances--called immunostimulants--of natural and synthetic origins and with different mechanisms of action have been introduced in some countries for the prevention of ARTIs in children. Recently, research focused on one of these compounds, Pidotimod, has attempted to better clarify and define its mechanisms of action both in vitro and in vivo. In this paper, we critically examine the most recent findings on Pidotimod. Certainly the improvement of research methodology in the last 20 years and the acquired knowledge in various fields of clinical immunology should be the starting point for research on Pidotimod. Preclinical research will be essential to better understand the mechanisms of action of this compound. However, in vivo studies, especially randomised control trials, will be necessary to establish the real efficacy of Pidotimod in the prevention of ARTIs in paediatric age.