Delayed puberty and response to testosterone in a rat model of colitis

Metabolomic and transcriptomic responses of mouse testis to the dextran sulfate sodium induced colitis

Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis, are widespread in developed countries and gradually increasing in developing countries. Evidences showed that man with CD has a decrease of serum testosterone, but how IBD take effects on testicular testosterone synthesis is not well elucidated. To investigate the effects of IBD on testis, we analyzed testicular metabolome and transcriptome data of the dextran sulfate sodium (DSS) induced IBD mice. As a result, metabolomic data showed that DSS indeed induced androgen decrease in mouse testis. Correspondingly, androgen synthesis associated genes, especially Lhcgr, were down-regulated in DSS testis. From the metabolomic data, we found vitamin intake associated metabolites vitamin B2 and pyridoxamine were significantly decreased, whereas fatty acid metabolism associated molecules N-lauroylglycine and N-decanoylglycine were increased in DSS testis. In addition, we found 8-hydroxy-deoxyguanosine, a DNA oxidative damage marker, and 8-oxoguanine, a molecule responsible for DNA damage repair, were also changed in DSS testis. Simultaneously, our data also showed that DSS up-regulated the expression of meiosis initiation associated gene Stra8 and oxygen transport associated genes in testis. In summary, these results depicted the complex effects of colitis on testis. These metabolites and transcripts changed in DSS testis could be used as potential targets for IBD treatment or symptom relieve.

Cyanidin-3-O-Glucoside Supplement Improves Sperm Quality and Spermatogenesis in a Mice Model of Ulcerative Colitis

Impaired fertility and low sperm quality are the global health problem with high attention. It has been noted that inflammation may impact fertility by affecting testicular spermatogenesis. Cyanidin-3-O-glucoside is a natural functional pigment with various health benefits. Nevertheless, studies on the mechanism by which C3G protects male reproduction in mice with ulcerative colitis remain scarce. The purpose of this study is to illustrate the potential mechanism of C3G for improving impaired fertility caused by colitis. A DSS-induced colitis model was applied to assess the effects of sperm quality with colitis and the health benefit role of C3G. Results indicated that C3G-treated mice exhibited higher body weight, longer colon length, less crypt damage and focal inflammation infiltration. Being consistent with that, low sperm count, low testis weight, high inflammation levels and abnormal thickness of seminiferous epithelium also observed in the DSS group were significantly recovered upon C3G treatment. These findings suggested that colitis has a close link to impaired fertility. Further analysis found that C3G could significantly suppress the inflammatory mediators in serum. Results conjointly indicated that C3G might improve the impaired fertility of mice with colitis by inhibiting inflammatory cytokines through the blood–testis barrier. C3G could be a promising daily supplement for ameliorating impaired fertility caused by colitis.

Sex Differences in Experimentally Induced Colitis in Mice: a Role for Estrogens

Sex differences have been found in the incidence and progression of inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease. The reported differences in observational studies are controversial, and the effects of sex hormones on the pathogenesis of IBD are not clear. The aim of this study was to analyze sex differences in the progression of experimentally induced colitis. Experimental colitis was induced in adult mice by adding 2% dextran sodium sulfate (DSS) into drinking water. Male and female mice were used as intact, gonadectomized, and supplemented with either estradiol or testosterone. In comparison to males, female mice with induced colitis had significantly longer colon (p < 0.05), lower decrease in body weight (p < 0.001), and lower stool consistency score (p < 0.05). Histopathological analysis showed less inflammatory infiltrates (p < 0.001) and crypt damage (p < 0.001) in female mice. Female mice with colitis had also lower concentration of TNF-α in colon homogenates (p < 0.01). Supplementation with estradiol in ovariectomized mice ameliorated the severity of colitis. Female mice are partially protected against chemically induced colitis. This protection seems to be mediated by estradiol.

Increases in Sex Hormones during Anti-Tumor Necrosis Factor α Therapy in Adolescents with Crohn's Disease

OBJECTIVE

To evaluate children with Crohn's disease for inverse relationships between systemic inflammatory cytokines and sex hormone regulation in the context of anti-tumor necrosis factor α (TNF-α) therapy.

STUDY DESIGN

An observational study design was used to assess sex hormone and gonadotropin levels at the time of initiation of anti-TNF-α therapy and 10 weeks and 12 months later in 72 adolescents (Tanner stage 2-5) with Crohn's disease. Mixed-model linear regression was used to evaluate relationships between hormone levels, systemic inflammation, and dual-energy x-ray absorptiometry whole-body fat mass Z scores over the study interval.

RESULTS

Sex hormone Z scores increased significantly during the 10-week induction interval: testosterone Z scores in male patients increased from a median of -0.36 to 0.40 (P < .05) and estradiol Z scores in females increased from -0.35 to -0.02 (P < .01). In mixed model regression, the pediatric Crohn's disease activity index score, cytokine levels, and measures of inflammation were significantly and negatively associated with sex hormone Z scores and with luteinizing hormone and follicle-stimulating hormone levels, adjusted for sex and Tanner stage. Sex hormone and gonadotropin levels were not associated with body mass index or fat mass Z-scores.

CONCLUSIONS

Crohn's disease is associated with delayed maturation, and initiation of anti-TNF-α therapy was associated with significant and rapid increases in sex hormone and gonadotropin levels, in association with improvements in disease activity and measures of inflammation. These data are consistent with preclinical studies of the effects of inflammation on sex hormone regulation.

Growth and the Growth Hormone-Insulin Like Growth Factor 1 Axis in Children With Chronic Inflammation: Current Evidence, Gaps in Knowledge, and Future Directions

Growth failure is frequently encountered in children with chronic inflammatory conditions like juvenile idiopathic arthritis, inflammatory bowel disease, and cystic fibrosis. Delayed puberty and attenuated pubertal growth spurt are often seen during adolescence. The underlying inflammatory state mediated by proinflammatory cytokines, prolonged use of glucocorticoid, and suboptimal nutrition contribute to growth failure and pubertal abnormalities. These factors can impair growth by their effects on the GH-IGF axis and also directly at the level of the growth plate via alterations in chondrogenesis and local growth factor signaling. Recent studies on the impact of cytokines and glucocorticoid on the growth plate further advanced our understanding of growth failure in chronic disease and provided a biological rationale of growth promotion. Targeting cytokines using biological therapy may lead to improvement of growth in some of these children, but approximately one-third continue to grow slowly. There is increasing evidence that the use of relatively high-dose recombinant human GH may lead to partial catch-up growth in chronic inflammatory conditions, although long-term follow-up data are currently limited. In this review, we comprehensively review the growth abnormalities in children with juvenile idiopathic arthritis, inflammatory bowel disease, and cystic fibrosis, systemic abnormalities of the GH-IGF axis, and growth plate perturbations. We also systematically reviewed all the current published studies of recombinant human GH in these conditions and discussed the role of recombinant human IGF-1.

Growth problems in children with IBD

Crohn's disease in childhood causes linear growth retardation, which has a substantial effect on management of this disease. By contrast, growth is rarely a problem in children presenting with ulcerative colitis. Depending on how growth failure is defined, approximately one-third of children with Crohn's disease have growth retardation at diagnosis. Although corticosteroids can suppress growth, decreased height at diagnosis demonstrates that this finding is a consequence of the disease and not merely an adverse effect of treatment. Both inflammation and undernutrition contribute to decreased height velocity. Increased cytokine production acts both on the hepatic expression of insulin-like growth factor 1 (IGF-1) and at chondrocytes of the growth plates of long bones. Growth hormone insensitivity caused by deranged immune function is a major mechanism in growth retardation. Resolution of inflammation is the cornerstone of treatment, but current studies on growth hormone and IGF-1 might yield therapies for those children whose inflammation is refractory to treatment.

Gender-dependent resiliency to stressful and metabolic challenges following prenatal exposure to high-fat diet in the p66(Shc-/-) mouse

Metabolic stressful challenges during susceptible time windows, such as fetal life, can have important implications for health throughout life. Deletion of the p66^Shc gene in mice leads to reduced oxidative stress (OS), resulting in a healthy and lean phenotype characterized by increased metabolic rate, resistance to high-fat diet (HFD)-induced obesity and reduced emotionality at adulthood. Here we hypothesize that p66^Shc−/− (KO) adult offspring might be protected from the detrimental effects induced by maternal HFD administered before and during pregnancy. To test such hypothesis, we fed p66^Shc+/+ (WT) and KO females with HFD for 13 weeks starting on 5 weeks of age until delivery and tested adult male and female offspring for their metabolic, neuroendocrine, and emotional profile. Prenatal diet affected stress responses and metabolic features in a gender-dependent fashion. In particular, prenatal HFD increased plasma leptin levels and decreased anxiety-like behavior in females, while increasing body weight, particularly in KO subjects. KO mice were overall characterized by metabolic resiliency, showing a blunted change in glycemia levels in response to glucose or insulin challenges. However, in p66^Shc−/− mice, prenatal HFD affected glucose tolerance response in an opposite manner in the two genders, overriding the resilience in males and exacerbating it in females. Finally, KO females were protected from the disrupting effect of prenatal HFD on neuroendocrine response. These findings indicate that prenatal HFD alters the emotional profile and metabolic functionality of the adult individual in a gender-dependent fashion and suggest that exposure to high-caloric food during fetal life is a stressful condition interfering with the developmental programming of the adult phenotype. Deletion of the p66^Shc gene attenuates such effects, acting as a protective factor.

Endocrine therapy for growth retardation in paediatric inflammatory bowel disease

Inflammatory bowel disease, particularly Crohn's disease (CD), can potentially cause growth failure during childhood as well as a reduction in final adult height. The underlying mechanism is multifactorial and includes poor nutrition, chronic inflammation, and the prolonged use of steroids. Despite major advances in the treatment of CD, current cohorts of children continue to display a deficit in linear growth and may qualify for growth-promoting hormonal therapy. However, currently there is limited evidence to support the use of endocrine therapy directed primarily at improving growth. This review is aimed at summarising the current evidence for growth impairment in inflammatory bowel disease and discusses the rationale for using growth promoting therapy.

Toxicological assessment of drugs that affect the endocrine system in puberty-related disorders

INTRODUCTION

Toxicologists must ensure that clinical risk-to-benefit analysis should be made both for genders and age groups, with any treatment. Puberty concerns physiological changes leading to organism's maturation. Pubertal growth disorders are increasing in last decades: besides causing physical and psychological distress, they may signal underlying endocrine-metabolic abnormalities with serious health consequences later on. Therapeutic approaches for some health conditions in childhood and adolescence are considered.

AREAS COVERED

The authors discuss how some diseases and treatments can impact pubertal growth. The authors look at particular immunological disorders such as asthma and how both the disease and treatment affects pubertal growth. They also discuss how the provision of available data can help to assess the dose-response of the drug, in these cases, and minimize the chance of side effects. The authors also discuss pediatric inflammatory bowel disease and how both the disease and treatment can mitigate the growth delay. Last, but not least, the authors discuss how the effects of the drugs used in the treatment of psychiatric disorders may accentuate endocrine issues in juvenile patients. Hyperprolactinemia induction by some antipsychotics is highlighted as an example.

EXPERT OPINION

Appropriate risk-benefit analysis of drugs prescribed during childhood and adolescence and intended to be used in the long term is required. Furthermore, future treatment strategies and safer compounds development should be supported by the knowledge of mechanisms underlying adverse side effects in pubertal growth and development.

Mechanisms and management of growth impairment in children affected by inflammatory bowel disease

Growth failure is a typical complication of pediatric inflammatory bowel disease. Factors responsible for stunting are multiple, and proinflammatory cytokines such as TNF-α and IL-6 play a pivotal role. Other determinants are disease severity and location, malnutrition, increased nutritional needs, genetics and drugs. The achievement of optimal linear growth and the remission of gastrointestinal symptoms are the principal targets of pediatric inflammatory bowel disease treatment. Thus, it is very important to assess and monitor linear growth at diagnosis and during follow-up of disease until final adult height achievement. The main strategies for management or prevention of growth impairment in these children are aimed to ensure optimal nutrition, obtain a rapid and complete remission of the disease avoiding or minimizing steroid usage and consider surgical resection, in particular in case of localized ileo or ileocecal disease, to achieve remission in early or mid-puberty. In the last few years, some authors have evaluated the effects of recombinant human growth hormone treatment in children and adolescents with inflammatory bowel disease. However, further studies are needed to better assess its efficacy.

Evolution of inflammatory diseases

The association of inflammation with modern human diseases (e.g. obesity, cardiovascular disease, type 2 diabetes mellitus, cancer) remains an unsolved mystery of current biology and medicine. Inflammation is a protective response to noxious stimuli that unavoidably occurs at a cost to normal tissue function. This fundamental trade-off between the cost and benefit of the inflammatory response has been optimized over evolutionary time for specific environmental conditions. Rapid change of the human environment due to niche construction outpaces genetic adaptation through natural selection, leading increasingly to a mismatch between the modern environment and selected traits. Consequently, multiple trade-offs that affect human physiology are not optimized to the modern environment, leading to increased disease susceptibility. Here we examine the inflammatory response from an evolutionary perspective. We discuss unique aspects of the inflammatory response and its evolutionary history that can help explain the association between inflammation and modern human diseases.

Partial normalization of pubertal timing in female mice with DSS colitis treated with anti-TNF-α antibody

BACKGROUND

Inflammatory bowel disease (IBD) and resultant colitis occurring prior to puberty are frequently associated with delayed puberty and losses of growth and bone mineralization. Some of this delay may be due to colonic inflammation and associated systemic inflammation. To date no treatments for IBD have been shown to normalize the timing of puberty. Our objective in this study was to determine whether there is a normalization of the timing of puberty during treatment of colitis using monoclonal antibodies (abs) to tumor necrosis factor (TNF)-α.

METHODS

We induced colitis in 23-day-old C57Bl6 female mice using 3% dextran sodium sulfate (DSS) for 7 days, followed by removal of DSS for an additional 3 days, resulting in 10 days of worsening colitis. DSS-treated mice received either TNF-α ab or Control ab on days 4 and 8 of colitis, while non-colitic Control mice received injections of TNF-α ab (Control + TNF-α ab). All groups were followed for the timing of vaginal opening until day of life 33, when they were euthanized for serum and colon collection.

RESULTS

The DSS + TNF-α ab group had lower levels of systemic interleukin (IL)-6 and a partial normalization of the timing of vaginal opening compared to the DSS + Control ab group. There were no differences in weight gain, growth, or colon histological inflammatory scores between the DSS + TNFα ab and DSS + Control ab groups over the course of the experiment.

CONCLUSIONS

We conclude that anti-TNF-α ab treatment causes a partial normalization of pubertal timing coincident with decreased systemic inflammation in DSS colitis. These data may have implications regarding growth and bone mineralization outcomes in pediatric IBD.

Changes in inflammation and QoL after a single dose of infliximab during ongoing IBD treatment

BACKGROUND AND OBJECTIVES

Infliximab is used increasingly as maintenance therapy for inflammatory bowel disease (IBD); however, the effects of a single maintenance dose of infliximab are unclear with respect to the quality of life and hormones related to growth and puberty. The aim of the present study was to determine the time course of inflammatory, hormonal, and quality-of-life changes following a single dose of infliximab in the context of ongoing therapy, as related to presence of IBD symptoms at time of administration.

METHODS

Children and adolescents with IBD receiving ongoing therapy with infliximab for clinical indications were recruited. The Pediatric Crohn's Disease Activity Index was determined at baseline and laboratory measures of high-sensitivity C-reactive protein (hsCRP) and hormones of growth and puberty were determined on days 0, 2, and 14. IBD-related quality of life (IMPACT III questionnaire) was tested on days 0 and 14. Subjects who had symptoms of IBD were compared with asymptomatic subjects.

RESULTS

Subjects overall and in the symptomatic group exhibited improved hsCRP by day 2 following treatment. Symptomatic subjects had higher Pediatric Crohn's Disease Activity Index scores and lower quality-of-life scores than asymptomatic subjects on day 0, whereas at day 14 there were no significant differences in quality-of-life scores between the 2 groups.

CONCLUSIONS

Even in the context of ongoing treatment, a single dose of infliximab results in decreased hsCRP, an improvement that is particularly noted among subjects who are symptomatic at the time of treatment. Although randomized trials are needed, these observational data may assist clinicians, patients, and families regarding expectations about timing and extent of these changes following a single treatment dose.

Sex differences in statural growth impairment in Crohn's disease: role of IGF-1

BACKGROUND

Growth impairment in Crohn's disease (CD) is more common in males than females for unknown reasons. Since insulin-like growth factor-1 (IGF-1) is important for statural growth, we hypothesized that IGF-1 levels are lower in males with CD.

METHODS

Sex differences in hormone Z-scores based on chronological age (CA-Z) and bone age (BA-Z) were examined in a cross-sectional study of 82 CD patients <21 years of age (43% female).

RESULTS

IGF-1 CA-Z and BA-Z-scores were 0.50 units (P = 0.04) and 1.24 units (P = 0.003) lower in males. Mean bone age (12.2 years) was lower than chronological age (13.1 years) (P < 0.0001). Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and albumin did not differ by sex (P ≥ 0.08), but were associated with IGF-1 CA-Z and BA-Z-scores (P ≤ 0.02). Insulin-like growth factor binding protein-3 (IGFBP-3) CA-Z and BA-Z-scores were 0.71 units (P = 0.004) and 1.26 units (P < 0.001) lower in males. Inflammatory markers were correlated with sex hormone CA-Z and BA-Z and pituitary hormone BA-Z-scores in males (P ≤ 0.03), but not females (P ≥ 0.25). IGF-1 BA-Z-scores were positively associated with height BA-Z-scores (P = 0.03). Mean height BA-Z-scores were lower in males (P = 0.03).

CONCLUSIONS

Lower IGF-1 levels in males may explain sex differences in growth impairment in CD. Inflammation appears to more adversely affect hormone levels and statural growth in males. Prospective longitudinal studies are needed to further clarify the role of IGF-1 in sex differences in statural growth impairment in pediatric CD.

The aetiology and impact of malnutrition in paediatric inflammatory bowel disease

Disease-associated undernutrition of all types is very common in paediatric inflammatory bowel disease (IBD). Recent weight loss remains one of the triad of clinical manifestations and a cornerstone for the diagnosis of Crohn's disease (CD), although significantly fewer patients now present as being underweight. Recent evidence suggests that the introduction of medical treatment will quickly restore body weight, although this does not reflect concomitant changes in body composition. CD children present with features of nutritional cachexia with normal fat stores but depleted lean mass. Poor bone health, delayed puberty and growth failure are additional features that further complicate clinical management. Suboptimal nutritional intake is a main determinant of undernutrition, although activation of the immune system and secretion of pro-inflammatory cytokines exert additional independent effects. Biochemically low concentrations of plasma micronutrients are commonly reported in IBD patients, although their interpretation is difficult in the presence of an acute phase response and other indices of body stores adequacy are needed. Anaemia is a common extraintestinal manifestation of the IBD child. Iron-deficient anaemia is the predominant type, with anaemia of chronic disease second. Decreased dietary intake, as a result of decreased appetite and food aversion, is the major cause of undernutrition in paediatric IBD. Altered energy and nutrient requirements, malabsorption and increased gastrointestinal losses are additional factors, although their contribution to undernutrition in paediatric CD needs to be studied further.

Puberty is delayed in male mice with dextran sodium sulfate colitis out of proportion to changes in food intake, body weight, and serum levels of leptin

In boys, inflammatory bowel disease often results in delayed puberty associated with decreased bone mineral density and decreased linear growth. Our goal was to investigate whether pubertal timing and levels of leptin differed between prepubertal male mice with colitis and food-restricted (FR) mice maintained at a similar weight. We induced colitis in 32-d-old male mice using dextran sodium sulfate (DSS), resulting in 10 d of worsening colitis. We followed up these mice for separation of the prepuce from the glans penis as a marker of pubertal progression. Compared with free-feeding control mice, DSS and FR mice had significantly lower weight on d 7-10 of treatment. DSS mice had later puberty than control and FR mice. DSS mice also had smaller testes, lower FSH levels, increased systemic cytokines, and increased colonic inflammation by histology. Leptin levels were similar between DSS and FR mice, whereas both had decreases in leptin compared with controls. We conclude that DSS colitis causes delayed puberty in sexually immature male mice beyond what is seen among FR mice of similar weight, food intake, and leptin levels. These experiments provide support for the hypothesis that pubertal delay in colitis is influenced by factors beyond poor weight gain alone.

Retinoids regulate a developmental checkpoint for tissue regeneration in Drosophila

Damage to Drosophila imaginal discs elicits a robust regenerative response from the surviving tissue [1-4]. However, as in other organisms, developmental progression and differentiation can restrict the regenerative capacity of Drosophila tissues. Experiments in Drosophila and other holometabolous insects have demonstrated that either damage to imaginal tissues [5, 6] or transplantation of a damaged imaginal disc [7, 8] delays the onset of metamorphosis. Therefore, in Drosophila there appears to be a mechanism that senses tissue damage and extends the larval phase to coordinate tissue regeneration with the overall developmental program of the organism. However, how such a pathway functions remains unknown. Here we demonstrate that a developmental checkpoint extends larval growth after imaginal disc damage by inhibiting the transcription of the gene encoding PTTH, a neuropeptide that promotes the release of the steroid hormone ecdysone. Using a genetic screen, we identify a previously unsuspected role for retinoid biosynthesis in regulating PTTH expression and delaying development in response to tissue damage. Retinoid signaling plays an important but poorly defined role in several vertebrate regeneration models [9-11]. Our findings demonstrate that retinoid biosynthesis in Drosophila is important for the maintenance of a condition that is permissive for regenerative growth.

Colitis causes delay in puberty in female mice out of proportion to changes in leptin and corticosterone

BACKGROUND

Inflammatory bowel disease that begins prior to puberty frequently causes a delay in puberty resulting in losses of growth, bone mineralization, and self esteem. A major cause of this pubertal delay is likely due in part to the effect of decreased levels of leptin on the function of the hypothalamic-pituitary-gonadal axis, though systemic inflammation is also thought to play a role.

METHODS

To investigate further whether low leptin levels alone were responsible for delayed puberty in colitis, we induced colitis in 23-day-old female mice using 3% dextran sodium sulfate (DSS), resulting in 10 days of worsening colitis. These mice were compared to controls that were free-feeding and food-restricted (FR) mice that were given only enough food to keep them the same weight as the DSS group. All groups were followed for the timing of vaginal opening until 33 days old, when they were euthanized and their serum collected.

RESULTS

DSS-treated mice exhibited later timing of vaginal opening relative to both of the other groups, as well as increased colonic inflammation by cytology and increased serum levels of interleukin (IL)-6 and tumor necrosis factor(TNF)-alpha. The difference in the timing of vaginal opening between the DSS and FR groups occurred despite equivalent serum levels of leptin between the groups and despite an increase in corticosterone in the FR group relative to both of the other groups.

CONCLUSIONS

We conclude that DSS colitis causes delay in puberty in sexually immature mice beyond what would be expected from decreases in weight and leptin levels.

The role of pro-inflammatory cytokines in inflammatory bowel disease growth retardation

Childhood inflammatory bowel disease (IBD) especially those with Crohn disease is commonly complicated by faltering growth and pubertal delay. Pro-inflammatory cytokines are often elevated in IBD and may affect linear growth and puberty either systemically or at the level of the growth plate. Further study of the underlying mechanisms of the deleterious effects of cytokines on the growth plate may improve management of faltering growth in childhood IBD. Well-controlled clinical studies of the respective effect of nutritional support, immunomodulatory therapy, biological agents and growth and puberty promoting agents on managing faltering growth also require further attention.

The cystic fibrosis transmembrane conductance regulator (Cftr) modulates the timing of puberty in mice

BACKGROUND

Delayed puberty is common among individuals with cystic fibrosis (CF) and is usually attributed to chronic disease and/or poor nutrition. However, it has recently been recognised that pubertal delay can occur even in the setting of good nutritional and clinical status. This finding, along with evidence that Cftr is expressed in rat brain, human hypothalamus, and a gonadotropin releasing hormone secreting cell line, raises the possibility that some of the pubertal delay in CF could stem directly from alterations in Cftr function that affect the hypothalamic-pituitary-gonadal axis.

METHODS

To examine this hypothesis, we investigated pubertal timing (as assessed by vaginal opening (VO)) in a mouse model of CF (Cftr(tm1Unc)) engineered to produce a truncated Cftr mRNA and referred to as S489X. Homozygous knockout, heterozygote, and wild type (WT) female mice were examined.

RESULTS

As expected, the S489X-/S489X- knockout mice, which have chronic inflammation and gastrointestinal disease, grew more slowly and had later onset of puberty than WT animals. We anticipated that the S489X-/S489X+ heterozygotes, which have no clinical CF phenotype, might display an intermediate timing of puberty. Surprisingly, however, these mice had earlier VO than WT. These findings were confirmed in a second, independent model of CF engineered to generate the deltaF508 mutation in mice. Again, the homozygotes displayed later pubertal timing, while the heterozygotes displayed earlier VO than the WT animals.

CONCLUSIONS

These data provide further evidence that Cftr can directly modulate the reproductive endocrine axis and raise the possibility that heterozygote mutation carriers may have a reproductive advantage.

Intestinal inflammation-induced growth retardation acts through IL-6 in rats and depends on the -174 IL-6 G/C polymorphism in children

Inflammatory diseases frequently impair linear growth. Crohn's disease inhibits growth in up to one third of affected children. In rats with trinitrobenzenesulphonic acid-induced colitis, 40% of growth impairment is attributable to inflammation, with the rest being due to undernutrition. In transgenic mice without inflammation, raised IL-6 retards growth, suppressing insulin-like growth factor (IGF)-I. We hypothesized that IL-6, induced by intestinal inflammation, suppresses growth and inhibits IGF-I expression. Therefore, an anti-IL-6 Ab was given to rats with trinitrobenzene-sulphonic acid colitis. The Ab did not improve nutrient intake or decrease inflammation compared with untreated disease controls, but it significantly restored linear growth (P = 0.023) and increased IGF-I (P = 0.05). In humans, the IL-6 -174 G/C promoter polymorphism affects IL-6 transcription, with the GG genotype inducing the greatest IL-6 levels. Because IL-6 is increased in Crohn's disease, we further hypothesized that growth failure would vary with the IL-6 -174 genotype. At diagnosis, among 153 children with Crohn's disease, those with the IL-6 GG genotype were more growth-retarded than those with the GC or CC genotypes (height SD score, -0.51 vs. -0.10; P = 0.031). Also, the patients with the IL-6 GG genotype had higher circulating levels of C-reactive protein, an IL-6-induced product (36 vs. 18 mg/dl, P = 0.028). However, their risk of developing Crohn's disease was similar to other genotypes when compared with 351 healthy controls (P = 0.7). Thus, the IL-6 -174 genotype mediates growth failure in children with Crohn's disease.