The circulating insulin-like growth factor system in children with coeliac disease: an additional marker for disease activity

Potential applications for rhIGF-I: Bone disease and IGFI

Growth hormone (GH) and insulin like growth factor-I (IGFI) are key bone trophic hormones, whose rising levels during puberty are critical for pubertal bone accrual. Conditions of GH deficiency and genetic resistance impact cortical and trabecular bone deleteriously with reduced estimates of bone strength. In humans, conditions of undernutrition (as in anorexia nervosa (AN), or subsequent to chronic illnesses) are associated with low IGF-I levels, which correlate with disease severity, and also with lower bone mineral density (BMD), impaired bone structure and lower strength estimates. In adolescents and adults with AN, studies have demonstrated a nutritionally acquired GH resistance with low IGF-I levels despite high concentrations of GH. IGF-I levels go up with increasing body weight, and are associated with rising levels of bone turnover markers. In short-term studies lasting 6-10 days, recombinant human IGF-I (rhIGF-I) administration in physiologic replacement doses normalized IGF-I levels and increased levels of bone formation markers in both adults and adolescents with AN. In a randomized controlled trial in adults with AN in which participants were randomized to one of four arms: (i) rhIGF-I with oral estrogen-progesterone (EP), (ii) rhIGF-I alone, (iii) EP alone, or (iv) neither for 9 months, a significant increase in bone formation markers was noted in the groups that received rhIGF-I, and a significant decrease in bone resorption markers in the groups that received EP. The group that received both rhIGF-I and EP had a significant increase in bone density at the spine and hip compared to the group that received neither. Side effects were minimal, with no documented fingerstick glucose of <50 mg/dl. These data thus suggest a potential role for rhIGF-I administration in optimizing bone accrual in states of undernutrition associated with low IGF-I.

The RhoGAP Myo9b Promotes Bone Growth by Mediating Osteoblastic Responsiveness to IGF-1

The Ras homolog A (RhoA) subfamily of Rho guanosine triphosphatases (GTPases) regulates actin-based cellular functions in bone such as differentiation, migration, and mechanotransduction. Polymorphisms or genetic ablation of RHOA and some of its regulatory guanine exchange factors (GEFs) have been linked to poor bone health in humans and mice, but the effects of RhoA-specific GTPase-activating proteins (GAPs) on bone quality have not yet been identified. Therefore, we examined the consequences of RhoGAP Myo9b gene knockout on bone growth, phenotype, and cellular activity. Male and female mice lacking both alleles demonstrated growth retardation and decreased bone formation rates during early puberty. These mice had smaller, weaker bones by 4 weeks of age, but only female KOs had altered cellular numbers, with fewer osteoblasts and more osteoclasts. By 12 weeks of age, bone quality in KOs worsened. In contrast, 4-week-old heterozygotes demonstrated bone defects that resolved by 12 weeks of age. Throughout, Myo9b ablation affected females more than males. Osteoclast activity appeared unaffected. In primary osteogenic cells, Myo9b was distributed in stress fibers and focal adhesions, and its absence resulted in poor spreading and eventual detachment from culture dishes. Similarly, MC3T3-E1 preosteoblasts with transiently suppressed Myo9b levels spread poorly and contained decreased numbers of focal adhesions. These cells also demonstrated reduced ability to undergo IGF-1-induced spreading or chemotaxis toward IGF-1, though responses to PDGF and BMP-2 were unaffected. IGF-1 receptor (IGF1R) activation was normal in cells with diminished Myo9b levels, but the activated receptor was redistributed from stress fibers and focal adhesions into nuclei, potentially affecting receptor accessibility and gene expression. These results demonstrate that Myo9b regulates a subset of RhoA-activated processes necessary for IGF-1 responsiveness in osteogenic cells, and is critical for normal bone formation in growing mice. © 2017 American Society for Bone and Mineral Research.

Extraintestinal manifestations of coeliac disease

Coeliac disease is a common disorder that can arise at any age and typically presents with a broad spectrum of symptoms. The disease is thought to be underdiagnosed, in part owing to the fact that coeliac disease is often characterized by associated conditions and extraintestinal manifestations that can misdirect and impede diagnosis. Some of these manifestations are direct consequences of autoimmunity, such as dermatitis herpetiformis or gluten ataxia, whereas others are indirectly related to inflammation and/or malabsorption including anaemia, osteoporosis, short stature and delayed puberty. Any organ from the central nervous system to joints, liver or teeth can be affected. In some cases, extraintestinal symptoms are the only clinical manifestations of coeliac disease or occur in conjunction with diarrhoea and malabsorptive symptoms. An increased awareness among medical practitioners of the variety of extraintestinal manifestations of coeliac disease is essential to improve diagnosis and treatment.

Celiac disease and short stature in children

Celiac disease (CD) is a genetically determined gluten-sensitive enteropathy resulting in nutrient malabsorption, with an increasing incidence worldwide. In CD children, short stature may be the only presenting clinical feature, even in the absence of gastrointestinal symptoms. Generally, a gluten-free diet (GFD) leads to rapid catch-up growth within 1-2 years. The pathogenesis of CD-associated short stature is still unclear. Besides the involvement of the growth hormone (GH)/IGF-I axis, other pathogenetic mechanisms may include autoimmune disorders of the pituitary gland and altered ghrelin secretion. Furthermore, some CD patients do not show catch-up growth during a GFD, despite reversion to seronegativity for CD markers. These subjects may have GH deficiency and could benefit from GH therapy. This review deals with the problem of linear growth in CD children and points to the importance of the evaluation of GH secretion in those children who show no catch-up growth after the introduction of a GFD.

Anti-pituitary antibodies in children with newly diagnosed celiac disease: a novel finding contributing to linear-growth impairment

OBJECTIVES

The possible autoimmune involvement of the pituitary gland in patients with celiac disease (CD) has been suggested but demonstrated in only a few patients on gluten-free diet. We aimed to assess the prevalence and clinical meaning of anti-pituitary antibodies (APA) in children and adolescents with the newly diagnosed CD.

METHODS

A total of 119 patients with CD (0.9-15.8 years old) attending the inpatient clinic of University Hospital were recruited for the cross-sectional study. Their height, weight, and body mass index (BMI) were recorded, and insulin-like growth factor-1 (IGF-1) and APA were assayed. APA was also determined in 98 sex- and age-matched controls.

RESULTS

APA were detected in 50 patients (42.0%), 15 of them with high titer (30%) and 35 with low titer (70%), and in 2 control subjects at low titer (2%) (P<0.001). IGF-1 was higher in patients with negative than with low titer (P=0.02) or high titer APA (P=0.03). Height was more reduced in high-titer APA patients than in the negative ones (P<0.01). Height was positively correlated with IGF-1 (P<0.01) and negatively with chronological age (P=0.001). IGF-1 was positively correlated with BMI (P<0.001). For height prediction the regression analysis showed the rank order 1 for chronological age and 2 for IGF-1.

CONCLUSIONS

In this paper we have shown a remarkable prevalence of positive APA in newly diagnosed CD patients. High APA titers are associated with height impairment, likely mediated by a reduction of IGF-1, thus suggesting that autoimmune pituitary process could induce a linear-growth impairment.

Commentary on "anti-pituitary antibodies in children with newly diagnosed celiac disease: a novel finding contributing to linear growth"

The pathogenesis of celiac disease (CD)-associated short stature is still unclear. The authors showed that newly diagnosed CD patients have a high prevalence of positive antipituitary antibodies that correlates with height impairment. Given the association of CD with other autoimmune disease, these authors' findings show one possible etiology for the poor growth seen in children with CD.

Is this really celiac disease? Pitfalls in diagnosis

Celiac disease (CD) is an autoimmune enteropathy triggered in susceptible individuals by ingestion of gliadin-containing grains. Although the autoimmune process targets mainly the intestinal mucosa, CD can manifest itself with a variety signs and symptoms affecting any organ or tissue. For many years, CD has been underdiagnosed because of poor awareness. However, studies showing a high prevalence of CD in North America, followed by a consensus conference on CD organized by the National Institutes of Health, have fueled a campaign to raise awareness among subspecialists and primary physicians. Nevertheless, guidelines for the diagnosis of CD remain poorly appreciated and many health care professionals remain confused about its proper management. This review is intended to clarify "facts and fantasies" about CD diagnosis.

Changes and relationships of IGFS and IGFBPS and cytokines in coeliac disease at diagnosis and on gluten-free diet

OBJECTIVE

To evaluate changes and relationships of IGFs and IGFBPs, serum interleukin 6 (IL-6) and tumour necrosis factor (TNF)-alpha, and auxological parameters at diagnosis of coeliac disease (CD) and at 6 months and 12 months after starting a gluten-free diet (GFD), compared with a control population.

PATIENTS

Twenty patients were enrolled at diagnosis (9 male, 11 female; age 9.6 +/- 0.8 years). A healthy population of 18 subjects (5 male, 13 female; age 11.3 +/- 0.6 years) comparable for age, sex and pubertal status served as controls at baseline.

MEASUREMENTS

Blood samples were taken at diagnosis, and at 6 months and 12 months after starting the GFD. Serum IGF-I, IGF-II, IGFBP-1, IGFBP-2, IGFBP-3, IL-6 and TNF-alpha were measured using commercial kits. Height (Ht) standard deviation score (SDS), body mass index (BMI) SDS and Ht velocity SDS were evaluated at diagnosis and at 6 months and 12 months after starting GFD.

RESULTS

In CD patients, both Ht SDS and BMI SDS increased during the first year of treatment, and Ht velocity SDS increased during the second 6 months of follow-up (P < 0.05). At diagnosis, IGF-I, IGF-II and IGFBP-3 were lower compared with controls, IGFBP-1 was similar, IGFBP-2, IL-6 and TNF-alpha were higher (P < 0.05). When on GFD, all peptides normalized and IGFBP-1 decreased. The IGF-I/IGFBP-2 and IGF-I/IGFBP-3 molar ratios were significantly reduced at diagnosis compared with those of controls, but were increased for both groups when on GFD. Although there was no apparent abnormality at diagnosis, the IGF-II/IGFBP-2 molar ratio increased significantly on GFD. Ht velocity SDS was positively correlated with IGFBP-3 (P < 0.05) and with the IGF-I/IGFBP-2 molar ratio (P < 0.05). Serum IL-6 was negatively correlated with IGF-I and positively with IGFBP-1 (P < 0.05).

CONCLUSIONS

The data obtained from this study confirm changes in the IGF and cytokine systems at diagnosis of CD which tend to normalize on the gluten-free diet. The two systems show relationships with each other and with linear growth.

Celiac disease: is the atypical really typical? Summary of the recent National Institutes of Health Consensus Conference and latest advances

Celiac disease (CD) is an immune-mediated enteropathy triggered by the ingestion of gluten in genetically susceptible individuals. Gluten is a protein component in wheat and other cereals, such as rye and barley. At present, the only available treatment is a strict gluten-free diet. Recent advances have increased our understanding of the molecular basis for this disorder. The past decade has seen new scientific developments in this disease and led to the formulation of new concepts of pathophysiology and clinical manifestations. There are several targets for new treatments. This article briefly summarizes the National Institutes of Health Consensus Statement and gives an overview of new findings in recent years and of future therapeutic options for CD.

Short-term gluten challenge in children with coeliac disease does not impair spontaneous growth hormone secretion

BACKGROUND

Growth retardation in children with coeliac disease has been attributed to impaired growth hormone (GH) secretion observed in stimulation tests.

OBJECTIVE

This study aimed at investigating the possible change in spontaneous GH secretion during a standardised gluten challenge.

PATIENTS

Twelve children with previous enteropathy suggesting coeliac disease and a normal pre-challenge biopsy on a gluten-free diet were included; eight of them completed all parts of the study, including repeated 24-h GH sampling.

METHODS

At the start and the end of a 5-6 weeks standardised gluten challenge, blood was drawn at a constant rate for 24 h and collected for GH analysis at 20-min intervals. The graph of plotted GH values was analysed by means of a computer program (PULSAR).

RESULTS

No significant changes were seen in the measures of maximum GH peak, baseline GH values, area under the curve over the baseline (AUCb), the number of GH peaks or mean GH concentration. GH secretion rate (GHt) increased slightly. None of the characteristics of the 24-h profile was significantly correlated to the change of IGF-I.

CONCLUSION

No impaired GH secretion was found. Thus, we speculate that decreased growth rate in celiac disease may not be primarily caused by changes in GH secretion. Instead it may be caused by changed peripheral sensitivity to GH.

Celiac disease

Celiac disease is more prevalent than it was previously thought to be, and screening of selected population groups may reveal many new cases. Tissue transglutaminase appears to have a significant role in the degradation of gliadin and antigen production. Specific gliadin epitopes have been defined using T-cell responses. Bone disease is a significant problem for patients with celiac disease but management guidelines are being developed. Refractory sprue (nonresponsive celiac disease) appears to be a manifestation of enteropathy-associated T-cell lymphoma in most cases.