Growth hormone enhances proinflammatory cytokine production by monocytes in whole blood

Cytokine response to resistance exercise in children with excess adiposity and Prader-Willi syndrome

Interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and irisin (cytokines) are affected by excess body fat (obesity), skeletal muscle, and resistance exercise (RE). The purpose of this study is to determine whether Prader-Willi Syndrome (PWS), a genetic cause for obesity (OB), or non-syndromic OB influences these cytokine responses to RE. Nine children with PWS (11.4 ± 3.3 years, 45.6 ± 5.2% BF), 11 children without OB (9.2 ± 1.4 years, 18.6 ± 5.0% BF), and 12 children with OB (9.6 ± 1.3 years, 40.4 ± 5.4% BF) participated. Children stepped onto an elevated platform wearing a weighted vest for 6 sets of 10 repetitions per leg separated by 1 min of rest. Blood samples were obtained before exercise (pre), immediately post (IP), and during recovery (+15 and +60 min). There were no group-by-time interactions for any cytokine; and neither time nor group effects for TNF-α or irisin (p ≥ 0.378). For IL-6, 60+ was higher than pre, IP, and +15 (p < 0.001). Children with PWS and OB had increased IL-6 than children without OB (p ≤ 0.038). Neither PWS nor OB affected IL-6, TNF-α or irisin responses to RE. However, excess body fat was associated with higher IL-6 concentrations.

The High-Risk Type 1 Diabetes HLA-DR and HLA-DQ Polymorphisms Are Differentially Associated With Growth and IGF-I Levels in Infancy: The Cambridge Baby Growth Study

OBJECTIVE

This study explored the link between HLA polymorphisms that predispose to type 1 diabetes and birth size, infancy growth, and/or circulating IGF-I in a general population-based birth cohort.

RESEARCH DESIGN AND METHODS

The Cambridge Baby Growth Study is a prospective observational birth cohort study that recruited 2,229 newborns for follow-up in infancy. Of these, 612 children had DNA available for genotyping single nucleotide polymorphisms in the HLA region that capture the highest risk of type 1 diabetes: rs17426593 for DR4, rs2187668 for DR3, and rs7454108 for DQ8. Multivariate linear regression models at critical ages (cross-sectional) and mixed-effects models (longitudinal) were performed under additive genetic effects to test for associations between HLA polymorphisms and infancy weight, length, skinfold thickness (indicator of adiposity), and concentrations of IGF-I and IGF-binding protein-3 (IGFBP-3).

RESULTS

In longitudinal models, the minor allele of rs2187668 tagging DR3 was associated with faster linear growth (P = 0.007), which was more pronounced in boys (P = 3 × 10^-7) than girls (P = 0.07), and was also associated with increasing IGF-I (P = 0.002) and IGFBP-3 (P = 0.003) concentrations in infancy. Cross-sectionally, the minor alleles of rs7454108 tagging DQ8 and rs17426593 tagging DR4 were associated with lower IGF-I concentrations at age 12 months (P = 0.003) and greater skinfold thickness at age 24 months (P = 0.003), respectively.

CONCLUSIONS

The variable associations of DR4, DR3, and DQ8 alleles with growth measures and IGF-I levels in infants from the general population could explain the heterogeneous growth trajectories observed in genetically at-risk cohorts. These findings could suggest distinct mechanisms involving endocrine pathways related to the HLA-conferred type 1 diabetes risk.

Acromegaly, inflammation and cardiovascular disease: a review

Acromegaly is characterized by Growth Hormone (GH) and Insulin-like Growth Factor 1 (IGF-1) excess. Uncontrolled acromegaly is associated with a strongly increased risk of cardiovascular disease (CVD), and numerous cardiovascular risk factors remain present after remission. GH and IGF-1 have numerous effects on the immune and cardiovascular system. Since endothelial damage and systemic inflammation are strongly linked to the development of CVD, and have been suggested to be present in both controlled as uncontrolled acromegaly, they may explain the presence of both micro- and macrovascular dysfunction in these patients. In addition, these changes seem to be only partially reversible after remission, as illustrated by the often reported presence of endothelial dysfunction and microvascular damage in controlled acromegaly. Previous studies suggest that insulin resistance, oxidative stress, and endothelial dysfunction are involved in the development of CVD in acromegaly. Not surprisingly, these processes are associated with systemic inflammation and respond to GH/IGF-1 normalizing treatment.

Growth hormone-mediated reprogramming of macrophage transcriptome and effector functions

Macrophages are an important component of the innate immune response. Priming and activation of macrophages is stimulated by cytokines (i.e IFNγ). However, growth hormone (GH) can also stimulate macrophage activation. Based on these observations, the goal of this work was to 1) to compare the transcriptome profile of macrophages activated in vitro with GH and IFNγ, and 2) to assess the impact of GH on key macrophage functional properties like reactive oxygen species (ROS) production and phagosomal proteolysis. To assess the global transcriptional and functional impact of GH on macrophage programming, bone marrow derived macrophages were treated with GH or IFNγ. Our data strongly support a potential link between GH, which wanes with age, and impaired macrophage function. The notable overlap of GH with IFNγ-induced pathways involved in innate immune sensing of pathogens and antimicrobial responses argue for an important role for GH in macrophage priming and maturation. By using functional assays that report on biochemical activities within the lumen of phagosomes, we have also shown that GH alters physiologically relevant processes such as ROS production and proteolysis. These changes could have far reaching impacts on antimicrobial capacity, signaling, and antigen presentation.

Systemic Complications of Acromegaly and the Impact of the Current Treatment Landscape: An Update

Acromegaly is a chronic systemic disease with many complications and is associated with increased mortality when not adequately treated. Substantial advances in acromegaly treatment, as well as in the treatment of many of its complications, mainly diabetes mellitus, heart failure, and arterial hypertension, were achieved in the last decades. These developments allowed change in both prevalence and severity of some acromegaly complications and furthermore resulted in a reduction of mortality. Currently, mortality seems to be similar to the general population in adequately treated patients with acromegaly. In this review, we update the knowledge in complications of acromegaly and detail the effects of different acromegaly treatment options on these complications. Incidence of mortality, its correlation with GH (cumulative exposure vs last value), and IGF-I levels and the shift in the main cause of mortality in patients with acromegaly are also addressed.

Interactions between the growth hormone and cytokines - A review

Numerous reports on the interactions between the immune and endocrine systems, especially growth hormone axis, can be found in the literature. Growth hormone acts mainly indirectly through insulin-like growth factor-1, which stimulates the growth and development processes, metabolism of lipids, proteins, and carbohydrates, and it also has a modulating effect on the cells of the immune system. Several studies have been conducted on the influence of growth hormone therapy on the immunological parameters in children and adults with and without growth hormone deficiency. However, there have been no definite results and some of them have been even contradictory. Some studies have suggested that administration of growth hormone increases the production of tumor necrosis factor and certain pro- and anti-inflammatory cytokines; whereas other studies have demonstrated the lack of correlation between growth hormone and interleukins. The aim of this paper was to evaluate the available literature on the interaction between growth hormone and TNF-α, pro-inflammatory (IL-1β, IL-2, IL-6) and anti-inflammatory (IL-4, IL-10) interleukins.

Direct and cytokine-mediated effects of albumin-fused growth hormone, TV-1106, on CYP enzyme expression in human hepatocytes in vitro

Some biologics can modulate cytokines that may lead to changes in expression of drug‐metabolizing enzymes and cause drug‐drug interactions (DDI). DDI potential of TV‐1106—an albumin‐fused growth hormone (GH)—was investigated. In this study, human blood was exposed to recombinant human growth hormone (rhGH) or TV‐1106, followed by isolation of the plasma and its application to human hepatocytes. While the treatment of blood with rhGH increased multiple cytokines, treatment of blood with TV‐1106 had no effect on any of the nine cytokines tested. The interleukin (IL)‐6 concentration was higher in the rhGH then in the TV‐1106‐treated plasma (P < .05). While rhGH had little or no effect on CYP1A2 or CYP2C19 mRNA but increased CYP3A4 mRNA twofold, TV‐1106 had little or no effect on cytochrome P450 (CYP) mRNAs in hepatocytes. Although the plasma from rhGH‐treated blood lowered CYP1A2 activity, the TV‐1106 plasma had no effect on CYP activities. The CYP1A2 activity was lower in the rhGH‐ then in the TV‐1106‐plasma treated hepatocytes (P < .05). The results indicated that fusing GH with albumin made TV‐1106 an unlikely participant of CYP1A2, CYP2C19 or CYP3A4‐facilitated, direct or cytokine‐driven DDI.

Modulation of Tryptophan and Serotonin Metabolism as a Biochemical Basis of the Behavioral Effects of Use and Withdrawal of Androgenic-Anabolic Steroids and Other Image- and Performance-Enhancing Agents

Modulation of tryptophan (Trp) metabolism may underpin the behavioral effects of androgenic-anabolic steroids (AAS) and associated image and performance enhancers. Euphoria, arousal, and decreased anxiety observed with moderate use and exercise may involve enhanced cerebral serotonin synthesis and function by increased release of albumin-bound Trp and estrogen-mediated liver Trp 2,3-dioxygenase (TDO) inhibition and enhancement of serotonin function. Aggression, anxiety, depression, personality disorders, and psychosis, observed on withdrawal of AAS or with use of large doses, can be caused by decreased serotonin synthesis due to TDO induction on withdrawal, excess Trp inhibiting the 2 enzymes of serotonin synthesis, and increased cerebral levels of neuroactive kynurenines. Exercise and excessive protein and branched-chain amino acid intakes may aggravate the effects of large AAS dosage. The hypothesis is testable in humans and experimental animals by measuring parameters of Trp metabolism and disposition and related metabolic processes.

Chronic limb-threatening ischemia could benefit from growth hormone therapy for wound healing and limb salvage

Revascularization for chronic limb-threatening ischemia (CLTI) is necessary to alleviate symptoms and wound healing. When it fails or is not possible, there are few alternatives to avoid limb amputation in these patients. Although experimental studies with stem cells and growth factors have shown promise, clinical trials have demonstrated inconsistent results because CLTI patients generally need arteriogenesis rather than angiogenesis. Moreover, in addition to the perfusion of the limb, there is the need to improve the neuropathic response for wound healing, especially in diabetic patients. Growth hormone (GH) is a pleiotropic hormone capable of boosting the aforementioned processes and adds special benefits for the redox balance. This hormone has the potential to mitigate symptoms in ischemic patients with no other options and improves the cardiovascular complications associated with the disease. Here, we discuss the pros and cons of using GH in such patients, focus on its effects on peripheral arteries, and analyze the possible benefits of treating CLTI with this hormone.

Focus on growth hormone deficiency and bone in adults

Growth hormone (GH) exerts several effects on the skeleton, mediated either directly or indirectly, leading to increased bone formation and resorption rates. Patients with growth hormone deficiency (GHD) of adult onset have decreased bone mineral density (BMD) and increased fracture risk. Some, but not all, studies have found that adults with childhood onset GHD also have lower BMD than healthy controls. Adults with GHD of childhood onset have smaller bone dimensions, leading to possible underestimation of areal BMD (measured by dual energy X-ray absorptiometry), thus potentially confounding the interpretation of densitometric data. Available data suggest that patients with childhood onset GHD are at increased fracture risk. Prospective studies and some clinical trials found that GH replacement for at least 18-24 months leads to increased BMD. Retrospective and prospective data suggest that GH replacement is associated with decreased fracture risk in adults. However, data from randomized clinical trials are lacking.

Muscle and skeletal health in children and adolescents with GH deficiency

In addition to promoting linear growth, GH plays a key role in the regulation of bone and muscle development and metabolism. Although GH deficiency is frequently listed among the causes of secondary osteoporosis in children, its impact on bone and muscle health and on fracture risk is still not completely established. Current data suggest that childhood-onset GH deficiency can affect bone and muscle mass and strength, with GH replacement therapy exerting beneficial effects. Moreover, GH withdrawal at final height can result in reduced peak bone and muscle mass, potentially leading to increased fracture risk in adulthood. Thus, the muscle-bone unit in GH deficient subjects should be monitored during childhood and adolescence in order to prevent osteoporosis and increased fracture risk and GH replacement should be tailored to ensure an optimal bone and muscle health.

Long-lived hypopituitary Ames dwarf mice are resistant to the detrimental effects of high-fat diet on metabolic function and energy expenditure

Growth hormone (GH) signaling stimulates the production of IGF‐1; however, increased GH signaling may induce insulin resistance and can reduce life expectancy in both mice and humans. Interestingly, disruption of GH signaling by reducing plasma GH levels significantly improves health span and extends lifespan in mice, as observed in Ames dwarf mice. In addition, these mice have increased adiposity, yet are more insulin sensitive compared to control mice. Metabolic stressors such as high‐fat diet (HFD) promote obesity and may alter longevity through the GH signaling pathway. Therefore, our objective was to investigate the effects of a HFD (metabolic stressor) on genetic mechanisms that regulate metabolism during aging. We show that Ames dwarf mice fed HFD for 12 weeks had an increase in subcutaneous and visceral adiposity as a result of diet‐induced obesity, yet are more insulin sensitive and have higher levels of adiponectin compared to control mice fed HFD. Furthermore, energy expenditure was higher in Ames dwarf mice fed HFD than in control mice fed HFD. Additionally, we show that transplant of epididymal white adipose tissue (eWAT) from Ames dwarf mice fed HFD into control mice fed HFD improves their insulin sensitivity. We conclude that Ames dwarf mice are resistant to the detrimental metabolic effects of HFD and that visceral adipose tissue of Ames dwarf mice improves insulin sensitivity in control mice fed HFD.

Endocrine and Local IGF-I in the Bony Fish Immune System

A role for GH and IGF-I in the modulation of the immune system has been under discussion for decades. Generally, GH is considered a stimulator of innate immune parameters in mammals and teleost fish. The stimulatory effects in humans as well as in bony fish often appear to be correlated with elevated endocrine IGF-I (liver-derived), which has also been shown to be suppressed during infection in some studies. Nevertheless, data are still fragmentary. Some studies point to an important role of GH and IGF-I particularly during immune organ development and constitution. Even less is known about the potential relevance of local (autocrine/paracrine) IGF-I within adult and developing immune organs, and the distinct localization of IGF-I in immune cells and tissues of mammals and fish has not been systematically defined. Thus far, IGF-I has been localized in different mammalian immune cell types, particularly macrophages and granulocytes, and in supporting cells, but not in T-lymphocytes. In the present study, we detected IGF-I in phagocytic cells isolated from rainbow trout head kidney and, in contrast to some findings in mammals, in T-cells of a channel catfish cell line. Thus, although numerous analogies among mammals and teleosts exist not only for the GH/IGF-system, but also for the immune system, there are differences that should be further investigated. For instance, it is unclear whether the primarily reported role of GH/IGF-I in the innate immune response is due to the lack of studies focusing on the adaptive immune system, or whether it truly preferentially concerns innate immune parameters. Infectious challenges in combination with GH/IGF-I manipulations are another important topic that has not been sufficiently addressed to date, particularly with respect to developmental and environmental influences on fish growth and health.

Role of growth hormone in maturation and activation of dendritic cells via miR-200a and the Keap1/Nrf2 pathway

OBJECTIVES

Dendritic cells (DCs) are antigen-presenting cells that participate in the immune response; recently, it has been reported that growth hormone (GH) promotes their maturation. The aim of this study was to investigate mechanisms by which GH acts on DC maturation and activation.

MATERIALS AND METHODS

Human peripheral blood monocytes (HPBMs) were induced to become immature DCs and treated with GH to obtain mature DCs. An osteosarcoma mouse model was established by injection of LM8 cells to investigate anti-tumour effect of GH-induced DCs in vivo.

RESULTS

After administration of GH, DCs reduced miR-200a expression and nuclear Nrf2 accumulation; miR-200a down-regulation inhibited DC maturation. Nrf2 ubiquitination level was increased by Keap1 overexpression in murine bone marrow derived dendritic cells (BMDCs), which was cancelled by miR-200a in GH exposed cells. In vivo, tumour volume was significantly reduced by GH-treated DCs and the effect was reversed by overexpression of miR-200a.

CONCLUSIONS

GH promoted maturation and activation of DCs, and regulation of miR-200a played a part in this process by modulation of the Keap1/Nrf2 pathway.

Increased plasma chemokine levels in children with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is caused by loss of paternally expressed genes from the 15q11-q13 region and reportedly rearranged as a cause of autism. Additionally, increased inflammatory markers and features of autism are reported in PWS. Cytokines encoded by genes involved with inflammation, cell proliferation, migration, and adhesion play a role in neurodevelopment and could be disturbed in PWS as abnormal plasma cytokine levels are reported in autism. We analyzed 41 plasma cytokines in a cohort of well-characterized children with PWS between 5 and 11 years of age and unaffected unrelated siblings using multiplex sandwich immunoassays with the Luminex magnetic-bead based platform. Data were analyzed using ANOVA testing for effects of diagnosis, gender, body mass index (BMI) and age on the 24 cytokines meeting laboratory criteria for inclusion. No significant effects were observed for age, gender or BMI. The log-transformed levels of the 24 analyzable cytokines were examined simultaneously using MANOVA adjusting for age and gender and a main effect of diagnosis was found (P-value <0.03). Four of 24 plasma cytokine levels (MCP1, MDC, Eotaxin, RANTES) were significantly higher in children with PWS compared with controls and classified as bioinflammatory chemokines supporting a disturbed immune response unrelated to obesity status. BMI was not statistically different in the two subject groups (PWS or unaffected unrelated siblings) and chemokine levels were not correlated with percentage of total body fat. Additional studies are required to identify whether possible early immunological disturbances and chemokine inflammatory processes found in PWS may contribute to neurodevelopment and behavioral features.

Bone turnover, bone mineral density, and fracture risk in acromegaly: a meta-analysis

CONTEXT

GH excess causes an increase in bone turnover, but the consequences in terms of skeletal fragility have long been uncertain due to the heterogeneity of studies dealing with this topic.

OBJECTIVE

We conducted a meta-analysis of studies examining the effects of acromegaly on bone turnover, bone mineral density (BMD), and fractures. Furthermore, we evaluated the effects of sex, gonadal status, and activity of disease on skeletal end-points in acromegaly.

DATA SOURCES

We conducted MEDLINE and EMBASE systematic searches up to December 31, 2013.

STUDY ELIGIBILITY CRITERIA

Studies conducted in patients with acromegaly and reporting at least one determinant of skeletal fragility.

DATA EXTRACTION AND ANALYSIS

Study design, patient characteristics, interventions, and outcomes were independently extracted by two authors. We calculated the standardized mean difference (SMD) of bone turnover and BMD differences, whereas fractures were presented as relative frequencies in acromegaly and odds ratios between patients and controls.

RESULTS

Forty-one studies fulfilled eligibility criteria and were therefore selected for data extraction and analysis. A total of 1935 patients were included (eight to 206 per study). Acromegaly patients had higher bone formation (SMD, 1.49; 95% confidence interval [CI], 0.97-2.01; P < .0001) and bone resorption (SMD, 1.57; 95% CI, 1.03-2.10; P < .0001) as compared to control subjects, without significant differences in lumbar spine BMD. BMD at the femoral neck tended to be higher in acromegaly patients vs control subjects (SMD, 0.67; 95% CI, 0.07-1.27; P = .03). Patients with acromegaly had high frequency of vertebral fractures (odds ratio, 8.26; 95% CI, 2.91-23.39; P < .0001), in close relationship with male gender, hypogonadism, and active acromegaly.

LIMITATIONS

LIMITATIONS included heterogeneous study protocols with possible variability in the assessment of skeletal end-points.

CONCLUSIONS

Skeletal fragility is an emerging complication of acromegaly.

Developmental oestrogen exposure differentially modulates IGF-I and TNF-α expression levels in immune organs of Yersinia ruckeri-challenged young adult rainbow trout (Oncorhynchus mykiss)

Intensified aquaculture has strong impact on fish health by stress and infectious diseases and has stimulated the interest in the orchestration of cytokines and growth factors, particularly their influence by environmental factors, however, only scarce data are available on the GH/IGF-system, central physiological system for development and tissue shaping. Most recently, the capability of the host to cope with tissue damage has been postulated as critical for survival. Thus, the present study assessed the combined impacts of estrogens and bacterial infection on the insulin-like growth factors (IGF) and tumor-necrosis factor (TNF)-α. Juvenile rainbow trout were exposed to 2 different concentrations of 17β-estradiol (E2) and infected with Yersinia ruckeri. Gene expressions of IGF-I, IGF-II and TNF-α were measured in liver, head kidney and spleen and all 4 estrogen receptors (ERα1, ERα2, ERβ1 and ERβ2) known in rainbow trout were measured in liver. After 5 weeks of E2 treatment, hepatic up-regulation of ERα1 and ERα2, but down-regulation of ERß1 and ERß2 were observed in those groups receiving E2-enriched food. In liver, the results further indicate a suppressive effect of Yersinia-infection regardless of E2-treatment on day 3, but not of E2-treatment on IGF-I whilst TNF-α gene expression was not influenced by Yersinia-infection but was reduced after 5 weeks of E2-treatment. In spleen, the results show a stimulatory effect of Yersinia-infection, but not of E2-treatment on both, IGF-I and TNF-α gene expressions. In head kidney, E2 strongly suppressed both, IGF-I and TNF-α. To summarise, the treatment effects were tissue- and treatment-specific and point to a relevant role of IGF-I in infection.

Effect of GH/IGF-1 on Bone Metabolism and Osteoporsosis

Background. Growth hormone (GH) and insulin-like growth factor (IGF-1) are fundamental in skeletal growth during puberty and bone health throughout life. GH increases tissue formation by acting directly and indirectly on target cells; IGF-1 is a critical mediator of bone growth. Clinical studies reporting the use of GH and IGF-1 in osteoporosis and fracture healing are outlined. Methods. A Pubmed search revealed 39 clinical studies reporting the effects of GH and IGF-1 administration on bone metabolism in osteopenic and osteoporotic human subjects and on bone healing in operated patients with normal GH secretion. Eighteen clinical studies considered the effect with GH treatment, fourteen studies reported the clinical effects with IGF-1 administration, and seven related to the GH/IGF-1 effect on bone healing. Results. Both GH and IGF-1 administration significantly increased bone resorption and bone formation in the most studies. GH/IGF-1 administration in patients with hip or tibial fractures resulted in increased bone healing, rapid clinical improvements. Some conflicting results were evidenced. Conclusions. GH and IGF-1 therapy has a significant anabolic effect. GH administration for the treatment of osteoporosis and bone fractures may greatly improve clinical outcome. GH interacts with sex steroids in the anabolic process. GH resistance process is considered.

Preweaning growth hormone treatment ameliorates adipose tissue insulin resistance and inflammation in adult male offspring following maternal undernutrition

It is well established that early-life nutritional alterations lead to increased risk of obesity and metabolic disorders in adult life. Although it is clear that obesity gives rise to chronic low-grade inflammation, there is little evidence regarding the role of inflammation in the adipose tissue of undernourished (UN) offspring. GH reduces fat mass and has antiinflammatory properties. The present study examined the effect of maternal UN on adipose inflammation in adult offspring and whether GH treatment during a critical period of developmental plasticity could ameliorate metabolic dysfunction associated with a poor start to life. Sprague Dawley rats were assigned to chow (C) or UN (50% ad libitum; UN) diet throughout gestation. Male C and UN pups received saline (control saline [CS]/UN) or GH (2.5 μg/g/d; control growth hormone [CGH]/undernourished growth hormone [UNGH]) from days 3-21. Postweaning males were further randomized and fed either chow or high-fat diet until day 160. An ex vivo glucose uptake assay demonstrated adipose tissue from UN offspring displayed attenuated insulin-stimulated glucose uptake compared with CS, CGH, and UNGH. This was associated with increased insulin receptor, glucose transporter 4, and insulin receptor substrate 1 gene expression. Furthermore, UN demonstrated enhanced TNFα and IL-1β secretion from adipose explants and stromal vascular fraction cultures accompanied by increased adipose tissue gene expression of several key proinflammatory genes and markers of macrophage infiltration. Overall, UN offspring displayed a more potent immunophenotype, which correlated with decreased insulin sensitivity. Preweaning GH treatment negates these detrimental effects, indicating the potential for reversing metabolic dysfunction in UN adult offspring.

The effect of experimentally induced chronic hyperglycaemia on serum and pancreatic insulin, pancreatic islet IGF-I and plasma and urinary ketones in the domestic cat (Felis felis)

Like in humans, diabetes mellitus is on the rise in cats. Feline diabetes is a suitable model for human type-2 diabetes. We investigated magnitude and timing of insulin suppression with induced hyperglycaemia and its relationship to plasma and urinary ketones and to pancreatic islet insulin. IGF-I is under discussion as a protective mechanism but little is known about its role in diabetes in general and its distinct localisation in feline pancreatic islets in particular. Thirteen healthy, adult cats were allocated to 2 groups and infused with glucose to maintain their blood glucose at a high or moderate concentration for 42 days resulting in insulin secretion suppression. After initial increase, insulin levels declined to baseline but were still detectable in the blood at a very low level after 6 weeks of glucose infusion and then increased after a 3 week recovery period. While IGF-I in healthy cats was primarily located in glucagon cells, in hyperglycaemia-challenge IGF-I was pronounced in the β-cells 3 weeks after ceasation of infusion. Six/8 cats developing glucose toxicity became ketonuric after 3-4 weeks. Gross lipaemia occurred approx 1 week prior to ketonuria. Ketonuric cats required 1-2 weeks of insulin therapy after-infusion until β-cell recovery. In conclusion, ketosis and hyperlipidaemia are likely to occur in diabetic cats with glucose at 30 mmol/L, especially after ≥2 weeks. Three weeks after ceasation of infusions, clinical and morphological recovery occurred. We propose a local protective effect of IGF-I to support survival and insulin production in the hyperglycaemic state and recovery period.

Effect of ghrelin and its analogues, BIM-28131 and BIM-28125, on the expression of myostatin in a rat heart failure model

BACKGROUND

In chronic heart failure (CHF), cachexia is a hallmark of the terminal stage of this disease and is associated with a severely reduced quality of life and poor prognosis. Therapeutic options are currently not available. Ghrelin and its analogues BIM-28125 and BIM-28131 (now known as RM-131) have been shown to increase weight in a rat model of CHF. It has been further demonstrated that the expression of myostatin, a negative regulator of skeletal muscle mass, is increased in CHF. The aim of the study was to investigate the influence of ghrelin or its analogues on myostatin in CHF.

METHODS

In an animal model of CHF, Sprague-Dawley rats received either ghrelin or two ghrelin analogues BIM-28125 and BIM-28131 in two different concentrations (50 and 500 nmol/kg/day) compared to placebo. The compounds were delivered using osmotic mini pumps. The expression of myostatin was analyzed in skeletal muscle by RT-PCR and Western blot, and muscle mass of gastrocnemius muscle was measured. The plasma levels of tumor necrosis factor alpha (TNF-α) were measured.

RESULTS

The relative weight of the gastrocnemius muscle of the sham-operated group was significantly increased compared to placebo-treated CHF rats. The application of ghrelin analogue BIM-28125 and BIM-28131 in their higher concentrations led to a significant reduction in myostatin mRNA expression in comparison to placebo. Myostatin protein expression was significantly reduced in both concentrations of ghrelin and BIM-28131 and in the lower concentration of BIM-28125. The increase of TNF-α plasma concentration in the CHF-animals could be abolished by all used substances.

CONCLUSIONS

In an animal model of CHF, the expression of myostatin is significantly reduced in the skeletal muscle after application of ghrelin and most concentrations of its analogues BIM-28125 and BIM-28131 possibly due to anti-inflammatory effects.

Lipopolysaccharide-induced failure of the gut barrier is site-specific and inhibitable by growth hormone

BACKGROUND

Gut barrier failure caused by endotoxemia is a life-threatening problem. The present study aimed to determine whether any specific intestinal site is highly correlated with gut barrier failure, and whether recombinant human growth hormone (rhGH) can ameliorate gut barrier failure in a rat model of endotoxemia.

METHODS

Enterostomy tubes were surgically placed in adult male Sprague-Dawley rats three days before induction of endotoxemia by lipopolysaccharide (LPS) injection. Controls received no LPS. Rats were then randomly assigned to receive subcutaneous injections of rhGH (experimental, n = 30) or 0.9 % saline (control, n = 15) at 24, 48, or 72 h after LPS injection. Escherichia coli labeled with green fluorescent protein (GFP) were injected into the intestinal segment of all rats through the enterostomy tubes. The number of GFP-labeled E. coli detected in mesenteric lymph nodes was examined after 96 h. Apoptosis and proliferation rates of intestinal epithelial cells, and intestinal permeability were measured.

RESULTS

Endotoxemia led to high mortality, compared with the control group, and rhGH treatment did not improve survival. Intestinal permeability, reflected by translocation rates of GFP-labeled E. coli, and apoptosis rates in the LPS-induced endotoxemia group were higher than those in the non-endotoxemia control group, and the endotoxemia ileum group had the highest rates of both bacterial translocation and apoptosis. The LPS+GH group had less bacterial translocation and apoptosis than the LPS-induced endotoxemia group. In contrast, the proliferation rates were lower in the LPS group compared to the LPS+GH group.

CONCLUSIONS

Endotoxemia can induce gut barrier failure in rats, and the ileum is the site of greatest risk. The GH can reduce the incidence of endotoxemia-induced gut barrier failure, but not the associated mortality.

GH activity and markers of inflammation: a crossover study in healthy volunteers treated with GH and a GH receptor antagonist

INTRODUCTION

The GH/IGF1 axis may modulate inflammatory processes. However, the relationship seems complicated as both pro- and anti-inflammatory effects have been demonstrated.

METHODS/DESIGN

Twelve healthy volunteers (mean age 36, range 27-49 years) were treated in random order with increasing doses of GH for 3 weeks (first week 0.01  mg/kg per day, second week 0.02  mg/kg per day, and third week 0.03  mg/kg per day) or a GH receptor antagonist (pegvisomant; first week 10  mg/day and last two weeks 15  mg/day), separated by 8 weeks of washout. Circulating levels of the pro-inflammatory cytokines tumor necrosis factor α (TNFα (TNFA)), interleukin 6 (IL6), and IL1β (IL1B) and the acute phase proteins (APPs) C-reactive protein (CRP), haptoglobin, orosomucoid, YKL40 (CHI3L1), and fibrinogen were measured.

RESULTS

During GH treatment, IGF1 (median 131 (Inter-quartile range (IQR) 112-166) vs 390 (322-524) μg/l, P=0.002) increased together with TNFα (0.87 (0.74-1.48) vs 1.27 (0.80-1.69) ng/l, P=0.003), IL6 (1.00 (0.83-1.55) vs 1.35 (0.80-4.28) ng/l, P=0.045), and fibrinogen (9.2 (8.8-9.6) vs 11.1 (9.4-12.4) μM, P=0.002). By contrast, orosomucoid decreased (18.0 (15.5-24.3) vs 15.0 (15.0-17.0) μM, P=0.018). CRP, YKL40, and haptoglobin were unchanged. During pegvisomant treatment, IGF1 decreased (139 (117-171) vs 91 (78-114) ng/ml, P=0.005). Orosomucoid (21.0 (16.3-23.8) vs 22.0 (17.0-29.3) μM, P=0.036) and CRP (1.00 (0.62-1.77) vs 1.43 (0.71-3.29) mg/l, P=0.074) increased without an increase in pro-inflammatory cytokines.

CONCLUSIONS

GH/IGF1 action appears to modulate the initial stage of the inflammatory response as well as downstream processes elucidated by levels of APPs. The data suggest a complicated relationship not allowing any simple conclusions as to whether GH/IGF1 actions have mainly pro- or anti-inflammatory effects in vivo.

Growth hormone (GH) treatment acts on the endocrine and autocrine/paracrine GH/IGF-axis and on TNF-α expression in bony fish pituitary and immune organs

There exist indications that the growth hormone (GH)/insulin-like growth factor (IGF) axis may play a role in fish immune regulation, and that interactions occur via tumour necrosis factor (TNF)-α at least in mammals, but no systematic data exist on potential changes in GH, IGF-I, IGF-II, GH receptor (GHR) and TNF-α expression after GH treatment. Thus, we investigated in the Nile tilapia the influence of GH injections by real-time qPCR at different levels of the GH/IGF-axis (brain, pituitary, peripheral organs) with special emphasis on the immune organs head kidney and spleen. Endocrine IGF-I served as positive control for GH treatment efficiency. Basal TNF-α gene expression was detected in all organs investigated with the expression being most pronounced in brain. Two consecutive intraperitoneal injections of bream GH elevated liver IGF-I mRNA and plasma IGF-I concentration. Also liver IGF-II mRNA and TNF-α were increased while the GHR was downregulated. In brain, no change occurred in the expression levels of all genes investigated. GH gene expression was exclusively detected in the pituitary where the GH injections elevated both GH and IGF-I gene expression. In the head kidney, GH upregulated IGF-I mRNA to an even higher extent than liver IGF-I while IGF-II and GHR gene expressions were not affected. Also in the spleen, no change occurred in GHR mRNA, however, IGF-I and IGF-II mRNAs were increased. In correlation, in situ hybridisation showed a markedly higher amount of IGF-I mRNA in head kidney and spleen after GH injection. In both immune tissues, TNF-α gene expression showed a trend to decrease after GH treatment. The stimulation of IGF-I and also partially of IGF-II expression in the fish immune organs by GH indicates a local role of the IGFs in immune organ regulation while the differential changes in TNF-α support the in mammals postulated interactions with the GH/IGF-axis which demand for further investigations.

Molecular and functional analyses of growth hormone-releasing hormone (GHRH) from olive flounder (Paralichthys olivaceus)

Growth hormone-releasing hormone (GHRH) is an important neuroendocrine factor that stimulates the release of growth hormone (GH) from the anterior pituitary. Several nonmammalian GHRH-like peptides were reported previously to be encoded by PACAP and processed from the same transcript and prepropolypeptide. However, the true nonmammalian GHRHs in amphibian and fishes were only recently discovered. We identified and characterized the primary structure of the GHRH gene and determined its expression profiles under normal and infectious conditions in the teleost fish, Paralichthys olivaceus. The 142 amino acids of the GHRH precursor are encoded by six exons spanning 2290bp. The flounder GHRH precursor mRNA was constitutively expressed in the brain as well as gills and ovary. Inducible expression of GHRH mRNA was observed in the gills of Edwardsiella tarda-challenged fish. Induction of GHRH mRNA was highest at 24h post-bacterial challenge. Subsequently, the biological role of GHRH was investigated by exogenous treatment of flounder embryogenic cells (hirame natural embryonic cells, HINAE cells) and primary cultured pituitary cells with a synthetic GHRH peptide (fGHRH-28). The 10(-6)M concentration of fGHRH-28 produced intracellular cAMP in HINAE cells and induced growth hormone mRNA in both of HINAE and pituitary cells. The profiles of TNF-α mRNA expression differed from HINAE and pituitary cells after fGHRH-28 treatment. TNF-α mRNA levels elevated approximately 3-fold in HINAE cells, but decreased to one-third in pituitary cells stimulated by fGHRH-28. These results suggest that the flounder GHRH plays roles in the bidirectional communication network between growth and immunity in fish.

Rejuvenation of the aging thymus: growth hormone-mediated and ghrelin-mediated signaling pathways

One of the major fundamental causes for the aging of the immune system is the structural and functional involution of the thymus, and the associated decline in de novo naïve T-lymphocyte output. This loss of naïve T-cell production weakens the ability of the adaptive immune system to respond to new antigenic stimuli and eventually leads to a peripheral T-cell bias to the memory phenotype. While the precise mechanisms responsible for age-associated thymic involution remain unknown, a variety of theories have been forwarded including the loss of expression of various growth factors and hormones that influence the lymphoid compartment and promote thymic function. Extensive studies examining two hormones, namely growth hormone (GH) and ghrelin (GRL), have demonstrated their contributions to thymus biology. In the current review, we discuss the literature supporting a role for these hormones in thymic physiology and age-associated thymic involution and their potential use in the restoration of thymic function in aged and immunocompromised individuals.

Effect of the combination of fibrin glue and growth hormone on intestinal anastomoses in a pig model of traumatic shock associated with peritonitis

BACKGROUND

Intra-abdominal sepsis and hemorrhagic shock have been found to impair the healing of intestinal anastomoses. The present study examined whether fibrin glue (FG) and recombinant human growth hormone (GH) can improve intestinal primary anastomotic healing in a pig model of traumatic shock associated with peritonitis. Further, the study was designed to investigate the probable mechanism of these agents.

METHODS

Female anesthetized pigs were divided into five groups. Group sham (n = 7), pigs without traumatic shock had small bowel resection anastomoses; group control (n = 14), pigs had bowel resection anastomoses 24 h after abdominal gunshot plus exsanguination/resuscitation; group FG (n = 14); group GH (n = 14); group FG/GH (n = 14), pigs received FG, recombinant GH, or both, respectively. Recombinant GH was given daily for 7 days. Blood samples were collected daily for measurement of interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha levels. Investigations also included adhesion formation, anastomotic bursting pressure, tensile strength, hydroxyproline (HP) content, myeloperoxidase (MPO), tumor necrosis factor (NF)-kappaB activity, and histology analysis 10 days later. A second experiment (n = 20 subjects assigned to each of the five groups) was designed to study survival during the first 20 postoperative days.

RESULTS

Traumatic shock associated with peritonitis led to significant decreases in intestinal anastomotic bursting pressures, tensile strengths, and tissue hydroxyproline content, along with severe adhesion formation, increases in MPO activity and NF-kappaB activity, and plasma levels of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6). Both FG and recombinant GH treatment led to early significant increases in plasma levels of TNF-alpha and IL-6. At the same time, FG alone, unlike recombinant GH alone, led to significant increases in anastomotic bursting pressures, tensile strength, and tissue HP content, along with decreases in anastomotic MPO and NF-kappaB activity and later plasma levels of TNF-a and IL-6. The FG group also developed more marked neoangiogenesis and collagen deposition on histology analysis. However, FG and recombinant GH synergistically effected improved anastomotic healing, abolishing the infaust effects promoted by recombinant GH. Adhesion formation after intestinal anastomosis could not be lowered by FG alone or by the combination of FG and recombinant GH. Both FG alone and FG/GH, in contrast to GH alone and control treatment, significantly prolonged the survival time of experimental animals.

CONCLUSIONS

We found that FG, but not recombinant GH, could lower the risk of anastomotic leakage, improve intestinal anastomotic healing, and prolong survival in a pig model of traumatic shock associated with peritonitis. Both FG and recombinant GH synergistically effected improved intestinal anastomotic healing. It was suggested that GH could be used locally to promote intestinal anastomotic healing in intra-abdominal peritonitis.

Failure to recover somatotropic axis function is associated with mortality from pediatric sepsis-induced multiple organ dysfunction syndrome

OBJECTIVES

To describe the associations between mediators of the somatotropic axis and mortality from sepsis-induced multiple organ dysfunction syndrome in children; and to examine the relationship between immune function and the somatotropic axis in this setting.

DESIGN

Retrospective study using banked plasma.

SETTING

Single mixed surgical/medical intensive care unit at a quaternary level children's hospital.

PATIENTS

A total of 24 children (n = 17 survivors, 7 nonsurvivors) with severe sepsis or septic shock and dysfunction of >or=2 organ systems.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma samples were available from days 3, 7, and 14 of multiple organ dysfunction syndrome. Insulin-like growth factor 1 and insulin-like growth factor binding protein 3 levels were measured by chemiluminescence. Immune function was quantified using previously determined ex vivo lipopolysaccharide-induced tumor necrosis factor-alpha production levels and absolute lymphocyte counts. Insulin-like growth factor 1 levels were lower in nonsurvivors compared with survivors (p = .004) with the greatest difference seen on day 14 (25 [25-69] ng/mL vs. 314 [123-582] ng/mL; p = .038). insulin-like growth factor binding protein 3 levels were reduced similarly over time (p = .019). A drop in plasma insulin-like growth factor binding protein 3 level at any time after day 3 of illness resulted in a 35-fold increased odds of death (odds ratio, 35 [1.6-750]; p = .004). Both ex vivo tumor necrosis factor-alpha and absolute lymphocyte count were reduced in nonsurvivors compared with survivors, but these differences occurred earlier (days 3 and 7).

CONCLUSIONS

These data suggest that prolonged reduction of somatotropic axis function is associated with mortality from pediatric sepsis-induced multiple organ dysfunction syndrome. Reductions in innate and adaptive immune function are common in this population and are associated with failure of recovery of the somatotropic axis, although the nature of these relationships remains incompletely understood.

Expression, regulation and biological actions of growth hormone (GH) and ghrelin in the immune system

Immune and neuroendocrine systems have bidirectional communications. Growth hormone (GH) and an orexigenic hormone ghrelin are expressed in various immune cells such as T lymphocytes, B lymphocytes, monocytes and neutrophils. These immune cells also bear receptors for hormones: growth hormone receptor (GHR) for GH and growth hormone secretagogue receptor (GHS-R) for ghrelin. The expression of GH in immune cells is stimulated by ghrelin as in anterior pituitary cells, whereas the regulation of GH secretion in the immune system by other peptides seems to be different from that in the anterior pituitary gland. Cytokines and mitogens enhance GH secretion from immune cells. GH has several biological actions in the immune system: enhancing thymopoiesis and T cell development, modulating cytokine production, enhancing B cell development and antibody production, priming neutrophils and monocytes for superoxide anion secretion, enhancing neutrophil adhesion and monocyte migration and anti-apoptotic action. Biological actions of ghrelin include attenuation of septic shock and anti-inflammatory actions, modulating phagocytosis, and enhancing thymopoiesis. The effect of ghrelin may be direct or through GH production, and that of GH may be direct or through insulin like growth factor-I (IGF-I) production. Elucidation of the roles of GH and ghrelin in the immune system may shed light on the treatment and prevention of immunological disorders such as AIDS and organ damages due to obesity/ageing-related chronic inflammation.

Low-dose growth hormone is cardioprotective in uremia

Growth hormone (GH) is required to maintain normal cardiac structure and function and has a positive effect on cardiac remodeling in experimental and possibly human disease. Cardiac resistance to GH develops in the uremic state, perhaps predisposing to the characteristic cardiomyopathy associated with uremia. It was hypothesized that administration of low-dosage GH may have a salutary effect on the cardiac remodeling process in uremia, but because high levels of GH have adverse cardiac effects, administration of high-dosage GH may worsen uremic cardiomyopathy. In rats with chronic renal failure, quantitative cardiac morphology revealed a decrease in total capillary length and capillary length density and an increase in mean intercapillary distance and fibroblast volume density evident. Low-dosage GH prevented these changes. Collagen and TGF-beta immunostaining, increased in chronic renal failure, were also reduced by GH, suggesting a mechanism for its salutary action. Low-dosage GH also prevented thickening of the carotid artery but did not affect aortic pathology. In contrast, high-dosage GH worsened several of these variables. These results suggest that low-dosage GH may benefit the heart and possibly the carotid arteries in chronic renal failure.

Survival and cellular immune functions in septic mice treated with growth hormone (GH) and insulin-like growth factor-I (IGF-I)

OBJECTIVE

GH was used to counteract the catabolic metabolism in critically ill patients until it was demonstrated that administration of GH was associated with an increased morbidity due to uncontrolled infections and sepsis. The immunomodulatory effect of GH and its main mediator IGF-I during systemic inflammation remain to be established. We therefore investigated the effect of GH and IGF-I on cellular immune functions in a murine model of sepsis.

DESIGN

Randomized animal study. Septic mice were treated with either saline, GH (1mg/kg/24h s.c.), IGF-I (4mg/kg/24h), or GH in combination with IGF-I over a 48h period.

SETTING

Level 1 trauma center, university research laboratory.

OBJECTS

Male NMRI mice.

MEASUREMENTS

clinical parameters (survival rate, body weight, body temperature, fluid intake, food intake, blood glucose levels) and cellular immune functions (splenocyte proliferation by using a (3)H-thymidine incorporation assay, splenocyte apoptosis by determination of Annexin V binding capacity, splenocyte IL-2, IL-6, and TNF-alpha release by using ELISA, and distribution of circulating immune cell subsets by FACScan).

RESULTS

Administration of GH did not affect clinical parameters or cellular immune functions in septic mice. In contrast, treatment with IGF-I alone or in combination with GH improved splenocyte proliferation and increased the ability of splenocytes to release IL-2 and IL-6 without affecting the survival rate or any other clinical parameter determined.

CONCLUSION

GH did not affect cellular immune functions or the survival rate in our murine sepsis model. In contrast, IGF-I improved splenocyte proliferation and cytokine release independently of GH but did not affect the determined clinical parameters of septic mice.

Systemic metabolic effects of combined insulin-like growth factor-I and growth hormone therapy in patients who have sustained acute traumatic brain injury

OBJECT

Hypermetabolism, hypercatabolism, refractory nitrogen wasting, hyperglycemia, and immunosuppression accompany traumatic brain injury (TBI). Pituitary dysfunction occurs, affecting growth hormone (GH) and plasma insulin-like growth factor-I (IGF-I) concentrations. The authors evaluated whether combination IGF-I/GH therapy improved metabolic and nutritional parameters after moderate to severe TBI.

METHODS

The authors conducted a prospective, randomized, double-blind study comparing combination IGF-I/GH therapy and a placebo treatment. Ninety-seven patients with TBI were enrolled in the study within 72 hours of injury and were assigned to receive either combination IGF-I/GH therapy or placebo. All patients received concomitant nutritional support. Insulin-like growth factor-I was administered by continuous intravenous infusion (0.01 mg/kg/hr), and GH (0.05 mg/kg/day) was administered subcutaneously. Placebo control group patients received normal saline solution in place of both agents. Nutritional and metabolic monitoring continued throughout the 14-day treatment period. The two groups did not differ in energy expenditure, nutrient intake, or use of insulin treatment. The mean daily serum glucose concentration was higher in the treatment group (123 +/- 24 mg/dl) than in the control group (104 +/- 11 mg/dl) (p < 0.03). A positive nitrogen balance was achieved within the first 24 hours in the treatment group and remained positive in that group throughout the treatment period (p < 0.05). This pattern was not observed in the control group. Plasma IGF-I concentrations were above 350 ng/ml in the treatment group throughout the study period. Overall, the mean plasma IGF-I concentrations were 1003 +/- 480.6 ng/ml in the treatment group and 192 +/- 46.2 ng/ml in the control group (p < 0.01).

CONCLUSIONS

The combination of IGF-I and GH produced sustained improvement in metabolic and nutritional endpoints after moderate to severe acute TBI.

Co-expression of interleukin-6 and human growth hormone in apparently normal prostate biopsies that ultimately progress to prostate cancer using low pH, high temperature antigen retrieval

Prostate cancer is the most common cancer in American men and the second leading cause of cancer deaths in this group. Both growth hormone (GH) and the inflammatory cytokine interleukin 6 (IL-6) have been implicated in prostate cancer progression. Studies in other systems have shown that an increase in GH results in an increase in IL-6 also. The current study demonstrated a parallel spatial and temporal expression of GH and IL-6 in cells in prostate cancer glandular acina cells. This study cannot determine if this expression is coincidental or causative, but it seems likely that the increase in GH could induce the expression of IL-6, since this is the case in other tissues. Optimal labelling for IL-6 in our study was achieved with low pH, high temperature antigen retrieval.

Effect of the Combination of Fibrin Glue and Growth Hormone on Incomplete Intestinal Anastomoses in a Rat Model of Intra-Abdominal Sepsis

BACKGROUND

The presence of established intra-abdominal sepsis has been considered a contraindication to primary anastomoses. Our hypothesis was that fibrin glue (FG), growth hormone (rhGH), and combination of them synergistically improve intestinal primary anastomotic healing in a rat model of intestinal fistulae with peritonitis.

MATERIALS AND METHODS

Male Wistar rats, induced intestinal fistulae with peritonitis after 24 h, were performed an enterectomy and intestinal anastomoses. Group A, rats (n = 60) had a complete anastomoses (end-to-end single layer anastomoses using 12 inverted interrupted 6-0 sutures) without peritonitis, group B, rats (n = 60) had a complete anastomoses after 24 h of peritonitis, group C rats had an incomplete anastomoses (four inverted interrupted sutures), groups D, E, F rats (n = 60) received FG, rhGH, or both of them, respectively. rhGH was given daily for 5 days. Anastomoses indicated the anastomotic bursting pressure (ABP), tensile strength, and hydroxyproline content, were determined.

RESULTS

On POD 1, ABP of group C and group D was significantly lower than that of other groups (P < 0.01); On POD 3, ABP could not be determined because of intestinal dehiscence in groups C and E, ABP was significantly higher in groups D and F than that of groups A and B (P < 0.01); the ABP increased after 5 days of operation in groups A, B, and F. At the same time, that of group D decreased (P < 0.01). On POD 5, the tensile strength was significantly higher in groups A, D, and F than that in groups C, and E. On POD 5, hydroxyproline content was higher in groups D and F compared to that in group C (P < 0.05).

CONCLUSIONS

These data suggested that FG improve intestinal primary anastomotic healing within post-operative 5 days in a rat model of intestinal fistulae with peritonitis. RhGH alone fails to improve intestinal anastomotic healing, and the combination of FG and rhGH have no synergistic effect to improves intestinal anastomotic healing.

Cellular localization of IL-18 and IL-18 receptor in pig anterior pituitary gland

Pro-inflammatory cytokine interleukin 18 (IL-18) has been proposed to have a role in modulating immuno-endocrine functions. Our previous study showed that IL-18 and IL-18 receptor (IL-18R) colocalized in somatotrophs of the bovine anterior pituitary gland, and the possibility that IL-18 acts on somatotrophs as an autocrine factor. In the present study, we investigated the localization of IL-18 and IL-18R in the pig anterior pituitary gland. RT-PCR analysis showed the expression of IL-18 and IL-18R mRNAin the pig anterior pituitary gland. Immunohistochemistry of IL-18 and specific hormones revealed the presence of IL-18 in somatotrophs, mammotrophs, thyrotrophs and gonadotrophs. IL-18R was localized in somatotrophs and thyrotrophs. Furthermore, the somatotrophs immunoreactive for IL-18 did not contain IL-18R. Thus, IL-18R and IL-18 were not colocalized in an identical somatotroph. These findings suggest that the localization of IL-18 in pig somatotrophs is different from that in bovine somatotrophs, although IL-18 closely associates with somatotrophs in the anterior pituitary glands in both species.

Ghrelin receptor agonist GHRP-2 prevents arthritis-induced increase in E3 ubiquitin-ligating enzymes MuRF1 and MAFbx gene expression in skeletal muscle

Chronic arthritis is a catabolic state associated with an inhibition of the IGF system and a decrease in body weight. Cachexia and muscular wasting is secondary to protein degradation by the ubiquitin-proteasome pathway. The aim of this work was to analyze the effect of adjuvant-induced arthritis on the muscle-specific ubiquitin ligases muscle ring finger 1 (MuRF1) and muscle atrophy F-box (MAFbx) as well as on IGF-I and IGF-binding protein-5 (IGFBP-5) gene expression in the skeletal muscle. We also studied whether the synthetic ghrelin receptor agonist, growth hormone releasing peptide-2 (GHRP-2), was able to prevent arthritis-induced changes in the skeletal muscle. Arthritis induced an increase in MuRF1, MAFbx (P < 0.01), and tumor necrosis factor (TNF)-alpha mRNA (P < 0.05) in the skeletal muscle. Arthritis decreased the serum IGF-I and its gene expression in the liver (P < 0.01), whereas it increased IGF-I and IGFBP-5 gene expression in the skeletal muscle (P < 0.01). Administration of GHRP-2 for 8 days prevented the arthritis-induced increase in muscular MuRF1, MAFbx, and TNF-alpha gene expression. GHRP-2 treatment increased the serum concentrations of IGF-I and the IGF-I mRNA in the liver and in the cardiac muscle and decreased muscular IGFBP-5 mRNA both in control and in arthritic rats (P < 0.05). GHRP-2 treatment increased muscular IGF-I mRNA in control rats (P < 0.01), but it did not modify the muscular IGF-I gene expression in arthritic rats. These data indicate that arthritis induces an increase in the activity of the ubiquitin-proteasome proteolytic pathway that is prevented by GHRP-2 administration. The parallel changes in muscular IGFBP-5 and TNF-alpha gene expression with the ubiquitin ligases suggest that they can participate in skeletal muscle alterations during chronic arthritis.

Delayed Leukocytosis and Cytokine Response to High-Force Eccentric Exercise

PURPOSE

Delayed leukocytosis after strenuous exercise is well documented, but the underlying mechanisms are not clear. In this study, we investigated the relationship between exercise-induced muscle damage and delayed leukocytosis, by utilizing an extreme eccentric exercise protocol.

METHODS

We obtained blood samples from 11 healthy men before and after 300 maximal eccentric actions with m. quadriceps. Maximal force-generating capacity was tested before and regularly during the 7 d after exercise. Blood was analyzed for leukocytes, growth hormone (GH), cortisol, granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating factor (M-CSF), interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1beta (MIP-1beta), creatine kinase (CK), C-reactive protein (CRP), complement activation products (C3bc and the terminal complement complex (TCC)), and chemotactic activity in plasma.

RESULTS

The force-generating capacity was reduced by 47 +/- 5% (mean +/- SEM) immediately after exercise. Blood concentration of neutrophils and monocytes and the plasma concentration of G-CSF, IL-6, and MCP-1 peaked 6 h after exercise, whereas M-CSF peaked immediately after exercise. Serum concentration of GH and cortisol also peaked immediately after exercise, whereas the serum concentration of CRP and CK peaked after 2 and 4 d, respectively. At 1 h after exercise, chemotactic activity in plasma was increased; at the same time, concentration of C3bc and TCC were decreased. A positive correlation was found between the acute loss of force and the delayed leukocytosis (r = 0.66; P < 0.05), between peak G-CSF and the delayed neutrophilia (r = 0.65, P < 0.05), between acute loss of force and changes in CK (r = 0.65, P < 0.05), between acute loss of force and changes in CRP (r = 0.65, P < 0.05), and between changes in GH and monocyte blood concentrations (r = 0.68, P < 0.05).

CONCLUSION

The degree of exercise-induced muscle damage seems to be reflected by the magnitude of the subsequent delayed leukocytosis. The signal between the exercised muscle and bone marrow must be investigated further, but G-CSF and GH are putative mobilizing factors.

Localization of interleukin-18 and its receptor in somatotrophs of the bovine anterior pituitary gland

A pro-inflammatory cytokine, interleukin 18 (IL-18), induces intracellular expression of IL-1 and the release of IL-6. IL-1 and IL-6 has been detected in anterior pituitary cells, suggesting that IL-18 is produced in anterior pituitary cells and may serve to aid immuno-endocrine regulation. In the present study, we addressed this hypothesis by investigating the intracellular localization of IL-18 and its receptor in bovine anterior pituitary gland. IL-18 mRNA and its protein were detected in the anterior pituitary gland by RT-PCR and Western blotting. In situ hybridization showed that IL-18 mRNA was expressed in the anterior pituitary cells. Immunohistochemistry of IL-18 and specific hormones revealed the presence of IL-18 in somatotrophs. Furthermore, the expression of GH mRNA in IL-18 immunoreactive cells was confirmed by immuno-laser microdissection. These results first demonstrated that somatotrophs produced IL-18. Subsequently, the distribution of the IL-18 receptor alpha (IL-18Ralpha) was investigated in order to understand IL-18 signaling among the anterior pituitary cells. Bovine IL-18Ralpha cDNA was partially sequenced and detected in the anterior pituitary gland by RT-PCR. Immunohistochemistry of IL-18Ralpha, IL-18 and GH showed that IL-18Ralpha was co-localized in IL-18 immunoreactive cells or somatotrophs. These data suggest that IL-18 acts on somatotrophs as an immuno-endocrine mediator through the autocrine pathway.

Cytokine induction during exertional hyperthermia is abolished by core temperature clamping: neuroendocrine regulatory mechanisms

The immunomodulatory effects of physiological temperature change remain poorly understood and inter-relationships between changes in core temperature, stress hormones and cytokines during exertional hyperthermia are not well established. This experimental study was designed to examine how cytokine (tumour necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-12 and IL-1ra (receptor antagonist)) and hormone (epinephrine (Epi), norepinephrine (NE), growth hormone (GH) and cortisol (CORT)) responses are modified when the exercise-induced rise in core temperature is attenuated or exacerbated by immersion in a water bath. Ten men ((mean +/- SD) age: 26.9 +/- 5.7 years; height 1.75 +/- 0.07 m; body mass 76.0 +/- 10.9 kg; O(2 peak): 48.0 +/- 12.4 mL kg(-1) min(-1)) completed two 40-min cycle ergometer exercise trials at 65% O(2 peak) while immersed to mid-chest. Rectal temperature (T(re)) peaked at 39.1 +/- 0.03 and 37.5 +/- 0.13 degrees C during the hot (39 degrees C) and cold (18 degrees C) conditions, respectively. Blood samples were collected before, during (20- and 40-min) and after (30- and 120-min) exercise. Increases in circulating NE (>350%), Epi (>500%), GH (>900%), IL-12 (>150%) and TNF-alpha (>90%) were greatest after 40-min exercise in the heat. Substantial elevations of CORT (80%), IL-1ra (150%) and IL-6 (>400%) did not occur until after exercise was complete. Core temperature clamping decreased the rise in circulating stress hormone concentrations and abolished increases in plasma cytokine concentrations. These findings suggest that exercise-associated elevations of T(re) mediate increases of circulating stress hormones, which subsequently contribute to induction of circulating cytokine release.

Suppressing lipolysis increases interleukin-6 at rest and during prolonged moderate-intensity exercise in humans

IL-6 induces lipolysis when administered to humans. Consequently, it has been hypothesized that IL-6 is released from skeletal muscle during exercise to act in a “hormonelike” manner and increase lipolysis from adipose tissue to supply the muscle with substrate. In the present study, we hypothesized that suppressing lipolysis, and subsequent free fatty acid (FFA) availability, would result in a compensatory elevation in IL-6 at rest and during exercise. First, we had five healthy men ingest nicotinic acid (NA) at 30-min intervals for 120 min at rest [10 mg/kg body mass (initial dose), 5 mg/kg body mass (subsequent doses)]. Plasma was collected and analyzed for FFA and IL-6. After 120 min, plasma FFA concentration was attenuated (0 min: 0.26 ± 0.05 mmol/l; 120 min: 0.09 ± 0.02 mmol/l; P < 0.01), whereas plasma IL-6 was concomitantly increased approximately eightfold (0 min: 0.75 ± 0.18 pg/ml; 120 min: 6.05 ± 0.89 pg/ml; P < 0.001). To assess the effect of lipolytic suppression on the exercise-induced IL-6 response, seven active, but not specifically trained, men performed two experimental exercise trials with (NA) or without [control (Con)] NA ingestion 60 min before (10 mg/kg body mass) and throughout (5 mg/kg body mass every 30 min) exercise. Blood samples were obtained before ingestion, 60 min after ingestion, and throughout 180 min of cycling exercise at 62 ± 5% of maximal oxygen consumption. IL-6 gene expression, in muscle and adipose tissue sampled at 0, 90, and 180 min, was determined by using semiquantitative real-time PCR. IL-6 mRNA increased in Con (rest vs. 180 min; P < 0.01) ∼13-fold in muscle and ∼42-fold in fat with exercise. NA increased (rest vs. 180 min; P < 0.01) IL-6 mRNA 34-fold in muscle, but the treatment effect was not statistically significant (Con vs. NA, P = 0.1), and 235-fold in fat (Con vs. NA, P < 0.01). Consistent with the study at rest, NA completely suppressed plasma FFA (180 min: Con, 1.42 ± 0.07 mmol/l; NA, 0.10 ± 0.01 mmol/l; P < 0.001) and increased plasma IL-6 (180 min: Con, 9.81 ± 0.98 pg/ml; NA, 19.23 ± 2.50 pg/ml; P < 0.05) during exercise. In conclusion, these data demonstrate that circulating IL-6 is markedly elevated at rest and during prolonged moderate-intensity exercise when lipolysis is suppressed.