The somatogenic hormones and insulin-like growth factor-1: stimulators of lymphopoiesis and immune function

Transcriptional Evaluation of Neuropeptides, Hormones, and Tissue Repair Modulators in the Skin of Gilthead Sea Bream (Sparus aurata L.) Subjected to Mechanical Damage

The skin of bony fish is the first physical barrier and is responsible for maintaining the integrity of the fish. Lesions make the skin vulnerable to potential infection by pathogens present in the aquatic environment. In this way, wound repair has barely been studied in gilthead sea bream. Thus, this study investigated the modulation of peripheral neuro-endocrine and tissue repair markers at the transcriptional level in the skin of teleost fish subjected to mechanical damage above or below the lateral line (dorsal and ventral lesions, respectively). Samples were evaluated using RT-qPCR at 2-, 4-, and 20-days post-injury. Fish with a ventral lesion presented a trend of progressive increase in the expressions of corticotropin-releasing hormone (crh), pro-opiomelanocortin-A (pomca), proenkephalin-B (penkb), cholecystokinin (cck), oxytocin (oxt), angiotensinogen (agt), and (less pronounced) somatostatin-1B (sst1b). By contrast, fish with a dorsal lesion registered no significant increase or biological trend for the genes evaluated at the different sampling times. Collectively, the results show a rapid and more robust response of neuro-endocrine and tissue repair markers in the injuries below than above the lateral line, which could be attributable to their proximity to vital organs.

Growth and body composition of dairy calves fed only milk replacer at 3 intakes

Determination of energy requirements for growth depends on measuring the composition of body weight (BW) gain. Previous studies have shown that the composition of gain can be altered in young dairy calves by composition of the milk replacer diet. Here, our objective was to determine body composition and the composition of empty body gain in young calves fed increasing amounts of a milk replacer containing adequate CP. Male Holstein calves underwent an adjustment period of 14 d after birth in which they were fed whole waste milk at 10% of BW. Calves were then stratified by BW and randomly assigned to either an initial harvest group (n = 11) or to groups fed 1 of 3 milk replacer amounts and harvested after 35 d of growth. All treatments consumed the same milk replacer containing 24.8% CP (dry matter [DM] basis; from all milk proteins) and 18.9% fat, reconstituted to 12.5% solids. Treatments were milk replacer fed at 1.25% of BW (DM basis; n = 6), 1.75% of BW (n = 6), or 2.25% of BW (n = 8), adjusted weekly as calves grew. Calves fed at 1.25% or 1.75% of BW were fed twice daily and those fed 2.25% of BW were fed 3 times daily. No starter was offered. Post harvest, the bodies of calves were separated into 4 fractions: carcass; total viscera minus digesta; head, hide, feet, and tail; and blood. The sum of those 4 fractions was empty BW, which increased linearly as amount of milk replacer increased. Final heart girth and body length, but not withers height, increased linearly as intake increased. Gain:feed increased linearly with increasing milk replacer. Feeding more milk replacer increased the amounts of lean tissue and fat in the body. The percentages of water and protein in the final body decreased linearly, whereas fat percentage and energy content increased linearly as intake increased. As gain increased, the percentage of protein in gain decreased and the percentage of fat increased, resulting in an increase of energy content of EBW gain. Efficiency of energy use (retained energy:gross energy intake) increased linearly but retained energy:metabolizable energy available for growth was not different among treatments. Efficiency of protein use increased quadratically as feeding rate increased; there was no further increase at 2.25% of BW. Plasma insulin-like growth factor 1, insulin, and glucose increased linearly, whereas urea-N decreased linearly, as milk replacer intake increased. Our data document changes in body composition that affect estimates of retained energy in the bodies of calves harvested at a common age. These data are important for calculations of energy requirements for young calves.

Aging augments obesity-induced thymic involution and peripheral T cell exhaustion altering the "obesity paradox"

Introduction

The incidence of obesity, a condition characterized by systemic chronic inflammation, has reached pandemic proportions and is a poor prognostic factor in many pathologic states. However, its role on immune parameters has been diverse and at times contradictory. We have previously demonstrated that obesity can result in what has been called the "obesity paradox" which results in increased T cell exhaustion, but also greater efficacy of immune checkpoint blockade in cancer treatment.

Methods

The role of obesity, particularly in the context of aging, has not been robustly explored using preclinical models. We therefore evaluated how age impacts the immune environment on T cell development and function using diet-induced obese (DIO) mice.

Results

We observed that DIO mice initially displayed greater thymopoiesis but then developed greater thymic involution over time compared to their lean counterparts. Both aging and obesity resulted in increased T cell memory conversion combined with increased expression of T cell exhaustion markers and Treg expansion. This increased T cell immunosuppression with age then resulted in a loss of anti-tumor efficacy by immune checkpoint inhibitors (ICIs) in older DIO mice compared to the younger DIO counterparts.

Discussion

These results suggest that both aging and obesity contribute to T cell dysfunction resulting in increased thymic involution. This combined with increased T cell exhaustion and immunosuppressive parameters affects immunotherapy efficacy reducing the advantage of obesity in cancer immunotherapy responses.

Developmental Programming of Fertility in Cattle-Is It a Cause for Concern?

Cattle fertility remains sub-optimal despite recent improvements in genetic selection. The extent to which an individual heifer fulfils her genetic potential can be influenced by fetal programming during pregnancy. This paper reviews the evidence that a dam's age, milk yield, health, nutrition and environment during pregnancy may programme permanent structural and physiological modifications in the fetus. These can alter the morphology and body composition of the calf, postnatal growth rates, organ structure, metabolic function, endocrine function and immunity. Potentially important organs which can be affected include the ovaries, liver, pancreas, lungs, spleen and thymus. Insulin/glucose homeostasis, the somatotropic axis and the hypothalamo-pituitary-adrenal axis can all be permanently reprogrammed by the pre-natal environment. These changes may act directly at the level of the ovary to influence fertility, but most actions are indirect. For example, calf health, the timing of puberty, the age and body structure at first calving, and the ability to balance milk production with metabolic health and fertility after calving can all have an impact on reproductive potential. Definitive experiments to quantify the extent to which any of these effects do alter fertility are particularly challenging in cattle, as individual animals and their management are both very variable and lifetime fertility takes many years to assess. Nevertheless, the evidence is compelling that the fertility of some animals is compromised by events happening before they are born. Calf phenotype at birth and their conception data as a nulliparous heifer should therefore both be assessed to avoid such animals being used as herd replacements.

It Takes Two to Tango: IGF-I and TSH Receptors in Thyroid Eye Disease

CONTEXT

Thyroid eye disease (TED) is a complex autoimmune disease process. Orbital fibroblasts represent the central orbital immune target. Involvement of the TSH receptor (TSHR) in TED is not fully understood. IGF-I receptor (IGF-IR) is overexpressed in several cell types in TED, including fibrocytes and orbital fibroblasts. IGF-IR may form a physical and functional complex with TSHR.

OBJECTIVE

Review literature relevant to autoantibody generation in TED and whether these induce orbital fibroblast responses directly through TSHR, IGF-IR, or both.

EVIDENCE

IGF-IR has traditionally been considered a typical tyrosine kinase receptor in which tyrosine residues become phosphorylated following IGF-I binding. Evidence has emerged that IGF-IR possesses kinase-independent activities and can be considered a functional receptor tyrosine kinase/G-protein-coupled receptor hybrid, using the G-protein receptor kinase/β-arrestin system. Teprotumumab, a monoclonal IGF-IR antibody, effectively reduces TED disease activity, proptosis, and diplopia. In addition, the drug attenuates in vitro actions of both IGF-I and TSH in fibrocytes and orbital fibroblasts, including induction of proinflammatory cytokines by TSH and TED IgGs.

CONCLUSIONS

Although teprotumumab has been proven effective and relatively safe in the treatment of TED, many questions remain pertaining to IGF-IR, its relationship with TSHR, and how the drug might be disrupting these receptor protein/protein interactions. Here, we propose 4 possible IGF-IR activation models that could underlie clinical responses to teprotumumab observed in patients with TED. Teprotumumab is associated with several adverse events, including hyperglycemia and hearing abnormalities. Underpinning mechanisms of these are being investigated. Patients undergoing treatment with drug must be monitored for these and managed with best medical practices.

Role of thymus in health and disease

The thymus is a primary lymphoid organ, essential for the development of T-cells that will protect from invading pathogens, immune disorders, and cancer. The thymus decreases in size and cellularity with age referred to as thymus involution or atrophy. This involution causes decreased T-cell development and decreased naive T-cell emigration to the periphery, increased proportion of memory T cells, and a restricted, altered T-cell receptor (TCR) repertoire. The changes in composition and function of the circulating T cell pool as a result of thymic involution led to increased susceptibility to infectious diseases including the recent COVID and a higher risk for autoimmune disorders and cancers. Thymic involution consisting of both structural and functional loss of the thymus has a deleterious effect on T cell development, T cell selection, and tolerance. The mechanisms which act on the structural (cortex and medulla) matrix of the thymus, the gradual accumulation of genetic mutations, and altered gene expressions may lead to immunosenescence as a result of thymus involution. Understanding the molecular mechanisms behind thymic involution is critical for identifying diagnostic biomarkers and targets for treatment help to develop strategies to mitigate thymic involution-associated complications. This review is focused on the consequences of thymic involution in infections, immune disorders, and diseases, identifying potential checkpoints and potential approaches to sustain or restore the function of the thymus particularly in elderly and immune-compromised individuals.

Insulin-like peptide 3 stimulates hemocytes to proliferate in anautogenous and facultatively autogenous mosquitoes

Most mosquito species are anautogenous, which means they must blood feed on a vertebrate host to produce eggs, while a few are autogenous and can produce eggs without blood feeding. Egg formation is best understood in the anautogenous mosquito Aedes aegypti, where insulin-like peptides (ILPs), ovary ecdysteroidogenic hormone (OEH) and 20-hydroxyecdysone (20E) interact to regulate gonadotrophic cycles. Circulating hemocytes also approximately double in abundance in conjunction with a gonadotrophic cycle, but the factors responsible for stimulating this increase remain unclear. Focusing on Ae. aegypti, we determined that hemocyte abundance similarly increased in intact blood-fed females and decapitated blood-fed females that were injected with ILP3, whereas OEH, 20E or heat-killed bacteria had no stimulatory activity. ILP3 upregulated insulin-insulin growth factor signaling in hemocytes, but few genes - including almost no transcripts for immune factors - were differentially expressed. ILP3 also stimulated circulating hemocytes to increase in two other anautogenous (Anopheles gambiae and Culex quinquefasciatus) and two facultatively autogenous mosquitoes (Aedes atropalpus and Culex pipiens molestus), but had no stimulatory activity in the obligately autogenous mosquito Toxorhynchites amboinensis. Altogether, our results identify ILPs as the primary regulators of hemocyte proliferation in association with egg formation, but also suggest this response has been lost in the evolution of obligate autogeny.

Production of recombinant Japanese eel (Anguilla japonica) growth hormones and their effects on early-stage larvae

Growth hormone (Gh) regulates somatic growth in fishes, particularly through the Gh - insulin-like growth factor-I (Igf-I) axis. In this study, recombinant Japanese eel Ghs with or without C-terminal peptides of human chorionic gonadotropin (CTP), which are known to prolong the half-life, were produced using the HEK 293 and CHO expression system. The effect of recombinant Gh administration to eel larvae on their somatic growth was investigated in short-term feeding experiments, and it was found that three types of recombinant Ghs with CTP (CTP-reGh, reGh-CTP and reGh-CTP × 2) were more effective in promoting somatic growth in eel larvae than recombinant Ghs without CTP. Among the three recombinant Ghs with CTP, reGh-CTP × 2 had the highest growth-promoting effects, however only when provided in the short term. After long-term administration of reGh-CTP × 2, there was no difference in growth between the Gh administrated group and the control group. The survival rate of eel larvae were not affected by recombinant Ghs. In addition, the mRNA expression of gh, Gh receptors, Igf-I and IGF-II were measured by quantitative real-time PCR, and significant reductions in the expression of gh, Gh receptors and Igf-I were observed. These findings provide useful tools to study the mechanisms of somatic growth and increase understanding of Gh regulation in anguillid eel larvae.

Insulin-like growth factor-1 and insulin-like growth factor binding protein-3: impact on early haematopoietic reconstitution following allogeneic haematopoietic stem cell transplantation

OBJECTIVES

The aim of the study was to investigate whether high endogenous levels of insulin-like growth factor-1 (IGF-1) and its binding protein-3 (IGFBP-3) were related to a faster reconstitution of different blood cell populations in the early phase after allogeneic myeloablative haematopoietic stem cell transplantation (HSCT).

METHODS

We measured IGF-1 and IGFBP-3 by chemiluminescence during the first three weeks after transplantation in 35 adult patients undergoing myeloablative HSCT and calculated area under the curve divided by time (AUC/t) for each patient.

RESULTS

Circulating levels of IGF-1 and IGFBP-3 correlated with counts of reticulocytes (r_s  = 0.44, p = .011 and r = 0.41, p = .017, respectively) and thrombocytes (r_s  = 0.38, p = .030 and r_s  = 0.56, p = .0008) three weeks post-transplant. Furthermore, high IGFBP-3 levels correlated with absolute lymphocyte counts 3 weeks post-HSCT (r_s  = 0.54, p = .012) and were associated with shorter time to neutrophil engraftment (r_s  = -0.35, p = .043). Both IGF-1 and IGFBP-3 levels were associated with the number of circulating natural killer cells one month after HSCT (r_s  = 0.42, p = .032 and r_s  = 0.57, p = .0026).

CONCLUSION

These data indicate that high levels of IGF-1 and IGFBP-3 relate to a faster haematopoietic reconstitution after HSCT and suggest a biological influence of these mediators in haematopoietic homeostasis in these patients.

Effects of Dietary Zinc-Methionine Supplementation During Pregnancy on the Whole-Genome Methylation and Related Gene Expression in the Liver and Spleen of Growing Goats: a Short Communication

The effect of replacing inorganic zinc with organic zinc in diets of pregnant goats was investigated on the development of the liver and spleen of offspring. Pregnant goats (n = 14; Xiangdong black goat, local breed) of similar parity and body weight (BW, 37.17 ± 5.28 kg) were selected and divided randomly into two groups: the zinc sulfate group (ZnSO₄; n = 7) and the methionine-chelated zinc group (Zn-Met; n = 7). Goats were fed for 45 days (day 106 of gestation to delivery). After delivering, lactating goats were fed a diet without extra zinc supplement. Kid goats were weaned at 2 months of age and both the groups were fed the same diet. All goats were fed a mixed diet and had free access to fresh water. Kid goats were slaughtered on day 100, and the liver and spleen were collected, weighed, and stored in liquid nitrogen for genomic DNA methylation and related gene expression determination. In the Zn-Met group, the liver organ index of kid goats showed an increasing trend (P < 0.10), but the methylation of the whole genome was not affected both in the liver and spleen (P > 0.10). Furthermore, the blood zinc content of the offspring was reduced (P < 0.05), and the expression of genes related to methylation were downregulated (P < 0.05) or showed a downward trend (P < 0.10) in the liver and spleen. These data indicated that goats feeding Zn-Met during pregnancy increased the offspring liver organ index without change in the genomic DNA methylation. It is speculated that the regulation of zinc finger protein Sp3 adjusted by blood zinc indirectly regulated the expression of methylation-related genes in the liver and spleen of the kid goats, thus enhancing the development and function of the immune system of the offspring.

Sirtuins and the prevention of immunosenescence

Aging of hematopoietic stem cells (HSCs) has been largely described as one underlying cause of senescence of the immune-hematopoietic system (immunosenescence). A set of well-defined hallmarks characterizes aged HSCs contributing to unbalanced hematopoiesis and aging-associated functional alterations of both branches of the immune system. In this chapter, the contribution of sirtuins, a family of conserved NAD⁺ dependent deacetylases with key roles in metabolism, genome integrity, aging and lifespan, to immunosenescence, will be addressed. In particular, the role of SIRT6 will be deeply analyzed highlighting a multifaceted part of this deacetylase in HSCs aging as well as in the immunosenescence of dendritic cells (DCs). These and other emerging data are currently paving the way for future design and development of rejuvenation means aiming at rescuing age-related changes in immune function in the elderly and combating age-associated hematopoietic diseases.

Growth hormone (GH) and growth hormone release factor (GRF) modulate the immune response in the SHK-1 cell line and leukocyte cultures of head kidney in Atlantic salmon

To clarify the role of growth hormone (GH) in the immune system of fish, we examine the comparative effect of GH and Growth Hormone Release Factor (GRF) on leukocytes culture of the head kidney of Atlantic salmon and the SHK-1 cell line. There are studies that associate the growth hormone (GH) / insulin-like growth factor (IGF) axis with the immune regulation of fish. However, there is no evidence that GH and GRF stimulate Atlantic salmon leukocyte cell lines, where there areńt reports on expression changes in different immune response markers. Thus, we investigated the effect of GH and GRF in Atlantic salmon leukocytes extracted from head kidney and the SHK-1 cell line on the different immune response markers such as: NLRC5, NLRC3, IL-1β, TNF-α, and IL-8 through qPCR. Our data suggest that GH increases the expression of NLRC5, NLRC3, and IL-1β mainly at 16 h post-stimulation in Atlantic salmon leukocytes. This indicates differential regulation between the two models used, helping us to better understand the independent action of GH on the immune system and the GH / IGF axis for future research.

Thymus-Pineal Gland Axis: Revisiting Its Role in Human Life and Ageing

For years the thymus gland (TG) and the pineal gland (PG) have been subject of increasingly in-depth studies, but only recently a link that can associate the activities of the two organs has been identified. Considering, on the one hand, the well-known immune activity of thymus and, on the other, the increasingly emerging immunological roles of circadian oscillators and the rhythmically secreted main pineal product, melatonin, many studies aimed to analyse the possible existence of an interaction between these two systems. Moreover, data confirmed that the immune system is functionally associated with the nervous and endocrine systems determining an integrated dynamic network. In addition, recent researches showed a similar, characteristic involution process both in TG and PG. Since the second half of the 20th century, evidence led to the definition of an effectively interacting thymus-pineal axis (TG-PG axis), but much has to be done. In this sense, the aim of this review is to summarize what is actually known about this topic, focusing on the impact of the TG-PG axis on human life and ageing. We would like to give more emphasis to the implications of this dynamical interaction in a possible therapeutic strategy for human health. Moreover, we focused on all the products of TG and PG in order to collect what is known about the role of peptides other than melatonin. The results available today are often unclear and not linear. These peptides have not been well studied and defined over the years. In this review we hope to awake the interest of the scientific community in them and in their future pharmacological applications.

Insulin-Like Growth Factors Are Key Regulators of T Helper 17 Regulatory T Cell Balance in Autoimmunity

Appropriate balance of T helper 17 (Th17) and regulatory T (Treg) cells maintains immune tolerance and host defense. Disruption of Th17-Treg cell balance is implicated in a number of immune-mediated diseases, many of which display dysregulation of the insulin-like growth factor (IGF) system. Here, we show that, among effector T cell subsets, Th17 and Treg cells selectively expressed multiple components of the IGF system. Signaling through IGF receptor (IGF1R) activated the protein kinase B-mammalian target of rapamycin (AKT-mTOR) pathway, increased aerobic glycolysis, favored Th17 cell differentiation over that of Treg cells, and promoted a heightened pro-inflammatory gene expression signature. Group 3 innate lymphoid cells (ILC3s), but not ILC1s or ILC2s, were similarly responsive to IGF signaling. Mice with deficiency of IGF1R targeted to T cells failed to fully develop disease in the experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis. Thus, the IGF system represents a previously unappreciated pathway by which type 3 immunity is modulated and immune-mediated pathogenesis controlled.

Maternal chlormequat chloride exposure disrupts embryonic growth and produces postnatal adverse effects

We showed previously that chlormequat chloride, a widely used plant growth regulator, could affect embryonic growth and growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis of rats. However, the potential effects of low dose chlormequat chloride exposure during pregnancy on embryonic and postnatal growth and development remain unclear. To further assess the risk of chlormequat chloride to human embryonic growth and postnatal health, we exposed maternal rats orally to the chemical during pregnancy at 5 mg/kg bw, a dose corresponding to the human acceptable daily intake (ADI) level set by World Health Organization (WHO), and determined the effects of chlormequat on embryo growth and postnatal health. We found that chlormequat chloride increased embryonic growth parameters, GH, and GH-releasing hormone (GHRH) levels, but did not affect somatostatin and IGF-1 on gestational day (GD) 11. In the pups of postnatal day (PD) 7, we observed increased head length, decreased body fat percentage, hypoglycemia, hyperlipidemia and hyperproteinemia. In conclusion, maternal exposure to chlormequat chloride during pregnancy disrupts the embryonic growth probably through its effects on growth regulators and even has adverse effects on postnatal health.

Review: Importance of colostrum supply and milk feeding intensity on gastrointestinal and systemic development in calves

Feeding management of the postnatal and preweaning calf has an important impact on calf growth and development during this critical period and affects the health and well-being of the calves. After birth, an immediate and sufficient colostrum supply is a prerequisite for successful calf rearing. Colostrum provides high amounts of nutrient as well as non-nutrient factors that promote the immune system and intestinal maturation of the calf. The maturation and function of the neonatal intestine enable the calf to digest and absorb the nutrients provided by colostrum and milk. Therefore, colostrum intake supports the start of anabolic processes in several tissues, stimulating postnatal body growth and organ development. After the colostrum feeding period, an intensive milk feeding protocol, that is, at least 20% of BW milk intake/day, is required to realise the calf potential for growth and organ development during the preweaning period. Insufficient milk intake delays postnatal growth and may have detrimental effects on organ development, for example, the intestine and the mammary gland. The somatotropic axis as the main postnatal endocrine regulatory system for body growth is stimulated by the intake of high amounts of colostrum and milk and indicates the promotion of anabolic metabolism in calves. The development of the forestomach is an important issue during the preweaning period in calves, and forestomach maturation is best achieved by solid feed intake. Unfortunately, intensive milk-feeding programmes compromise solid feed intake during the first weeks of life. In the more natural situation for beef calves, when milk and solid feed intake occurs at the same time, calves benefit from the high milk intake as evidenced by enhanced body growth and organ maturation without impaired forestomach development during weaning. To realise an intensive milk-feeding programme, it is recommended that the weaning process should not start too early and that solid feed intake should be at a high extent despite intensive milk feeding. A feeding concept based on intensive milk feeding prevents hunger and abnormal behaviour of the calves and fits the principles of animal welfare during preweaning calf rearing. Studies on milk performance in dairy cows indicate that feeding management during early calf rearing influences lifetime performance. Therefore, an intensive milk-feeding programme affects immediate as well as long-term performance, probably by programming metabolic pathways during the preweaning period.

Correlation of Plasma Level of Insulin-Like Growth Factor-1 (IGF-1) with Bacterial Index on Leprosy Patients in Bali

Background

Leprosy is an infection by Mycobacterium leprae, which influenced by cellular immunity. Leprosy tends to occur in low socio-economic and nutrition groups. Researchers try to prove the role of nutrition in the pathogenesis of leprosy. Insulin-like growth factor-1 (IGF-1) as a marker of nutritional status shown to play a role in cellular immunity.

Objective

To evaluate the correlation between IGF-1 with bacterial index (BI) on leprosy patients in Bali.

Methods

Cross-sectional study in Sanglah Public General Hospital, Denpasar of patients with paucibacillary (PB) and multibacillary (MB) leprosy were assessed for BI using slit-skin smear. All patients were tested for plasma IGF-1 using chemiluminescent immunometric assay Immulite. All data were analyzed using IBM SPSS ver. 24.0. The study has been approved by local Institutional Review Board with ethical clearance number 2017.02.1.0356.

Results

Our study involved 44 MB and 2 PB leprosy. The common age group affected was between 31~40 years old (23.9%), male (60.9%), and normal body mass index (BMI) (65.2%). Mean plasma IGF-1 level in PB leprosy was higher (91.07±0.74 ng/ml) than MB (82.74±6.44 ng/ml). The mean IGF-1 level decreases as BI increases in both groups (CI 95%=81.16~85.04; p<0.001). Pearson correlation test shows strong negative correlation (Pearson r=−0.976; p<0.001) with determinant coefficient (R₂) showing 95.2% (p<0.001).

Conclusion

In Balinese leprosy patients, severity of disease status measured by BI were found to be strongly correlated with the plasma IGF-1 level which may help preventing transmission in household contacts by improving nutritional status.

Early Postnatal IGF-1 and IGFBP-1 Blood Levels in Extremely Preterm Infants: Relationships with Indicators of Placental Insufficiency and with Systemic Inflammation

OBJECTIVE

To evaluate to what extent indicators of placenta insufficiency are associated with low concentrations of insulin-like growth factor 1 (IGF-1) and IGF-1-binding protein-1 (IGFBP-1) in neonatal blood, and to what extent the concentrations of these growth factors are associated with concentrations of proteins with inflammatory, neurotrophic, or angiogenic properties.

STUDY DESIGN

Using multiplex immunoassays, we measured the concentrations of IGF-1 and IGFBP-1, as well as 25 other proteins in blood spots collected weekly from ≥ 880 infants born before the 28th week of gestation, and sought correlates of concentrations in the top and bottom quartiles for gestational age and day the specimen was collected.

RESULTS

Medically indicated delivery and severe fetal growth restriction (sFGR) were associated with low concentrations of IGF-1 on the first postnatal day and with high concentrations of IGFBP-1 on almost all days. Elevated concentrations of IGF-1 and IGFBP-1 were accompanied by elevated concentrations of many other proteins with inflammatory, neurotrophic, or angiogenic properties.

CONCLUSION

Disorders associated with impaired placenta implantation and sFGR appear to account for a relative paucity of IGF-1 on the first postnatal day. Elevated concentrations of IGF-1 and especially IGFBP-1 were associated with same-day elevated concentrations of inflammatory, neurotrophic, and angiogenic proteins.

The Sleep-Immune Crosstalk in Health and Disease

Sleep and immunity are bidirectionally linked. Immune system activation alters sleep, and sleep in turn affects the innate and adaptive arm of our body's defense system. Stimulation of the immune system by microbial challenges triggers an inflammatory response, which, depending on its magnitude and time course, can induce an increase in sleep duration and intensity, but also a disruption of sleep. Enhancement of sleep during an infection is assumed to feedback to the immune system to promote host defense. Indeed, sleep affects various immune parameters, is associated with a reduced infection risk, and can improve infection outcome and vaccination responses. The induction of a hormonal constellation that supports immune functions is one likely mechanism underlying the immune-supporting effects of sleep. In the absence of an infectious challenge, sleep appears to promote inflammatory homeostasis through effects on several inflammatory mediators, such as cytokines. This notion is supported by findings that prolonged sleep deficiency (e.g., short sleep duration, sleep disturbance) can lead to chronic, systemic low-grade inflammation and is associated with various diseases that have an inflammatory component, like diabetes, atherosclerosis, and neurodegeneration. Here, we review available data on this regulatory sleep-immune crosstalk, point out methodological challenges, and suggest questions open for future research.

Insulin-like Growth Factor-I Receptor and Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is a complex disease process presumed to emerge from autoimmunity occurring in the thyroid gland, most frequently in Graves disease (GD). It is disfiguring and potentially blinding, culminating in orbital tissue remodeling and disruption of function of structures adjacent to the eye. There are currently no medical therapies proven capable of altering the clinical outcome of TAO in randomized, placebo-controlled multicenter trials. The orbital fibroblast represents the central target for immune reactivity. Recent identification of fibroblasts that putatively originate in the bone marrow as monocyte progenitors provides a plausible explanation for why antigens, the expressions of which were once considered restricted to the thyroid, are detected in the TAO orbit. These cells, known as fibrocytes, express relatively high levels of functional TSH receptor (TSHR) through which they can be activated by TSH and the GD-specific pathogenic antibodies that underpin thyroid overactivity. Fibrocytes also express insulin-like growth factor I receptor (IGF-IR) with which TSHR forms a physical and functional signaling complex. Notably, inhibition of IGF-IR activity results in the attenuation of signaling initiated at either receptor. Some studies suggest that IGF-IR-activating antibodies are generated in GD, whereas others refute this concept. These observations served as the rationale for implementing a recently completed therapeutic trial of teprotumumab, a monoclonal inhibitory antibody targeting IGF-IR in TAO. Results of that trial in active, moderate to severe disease revealed dramatic and rapid reductions in disease activity and severity. The targeting of IGF-IR with specific biologic agents may represent a paradigm shift in the therapy of TAO.

Physiological Adaptations to Milk Production that Affect the Fertility of High Yielding Dairy Cows

The high yielding dairy cow is expected to produce a substantial milk output every year and at the same time to conceive and maintain a pregnancy to term. To fulfil lifetime production potential a balance between yield, fertility and other influential factors has to be achieved. Any inability on the part of the management system to identify and rectify problems or on the part of the cow to cope with metabolic demands invariably results in economic or welfare issues. Our studies of high yielding dairy cows have revealed that some animals are capable of normal reproductive function whilst others are classic repeat breeders (requiring 3+ services per conception) or simply fail to rebreed. It is well established that the somatotrophic axis (growth hormone and insulin-like growth factors) drives lactation in ruminants but it is also intimately involved in reproductive processes. An awareness of metabolic adaptations to lactation that impact on reproduction in dairy cows is needed for appropriate management.

The objective of our studies was to explore the metabolic profiles of high yielding dairy cows to identify factors influencing their ovarian function and fertility, hence to characterise the physiological adaptations involved. Our studies revealed different relationships between progesterone profile categories and metabolic status post partum. Delayed ovulation (DOV) or persistent corpora lutea (PCL) may be an appropriate response to a nutritional state or physiological situation and it may therefore be inaccurate to refer to these as ‘abnormal’. Whilst associated with high milk yields, not all profile categories detrimentally affected fertility parameters. Delayed ovulation postcalving (DOV1) was identified as the most prevalent abnormal profile encountered in first lactation high yielding cows. This may have occurred because the cows were not yet physically mature and unable to sustain both milk production and growth. The condition lasted long enough (71 ± 8.3 days from calving) to have a detrimental impact on their overall fertility parameters and was associated with significant physiological changes, representative of tissue mobilisation. Although the incidence of persistent luteal phases (PCL1 and PCL2) in dairy cows is increasing, this condition was not found to have any substantial detrimental effects on fertility or production parameters of the primiparous or multiparous cows in these studies. The main reproductive problems in our high yielding primiparous and multiparous cows appeared to be a failure to ovulate and conceive at the expected time or to maintain a pregnancy. These situations were associated predominantly with high milk yields and low concentrations of plasma IGF-I. A failure to ovulate appears to occur when body reserves are mobilised to maintain milk yield at the expense of reproduction and seems most likely to occur in primiparous high yielding cows or those experiencing GH-resistance (low IGF-I) due to excessive body condition loss, reduced feed intakes and factors such as stress and disease. More detailed investigations of dietary means of increasing IGF-I and optimising insulin concentrations, targeted at important reproductive times, are required in high yielding dairy cows, to aid in their management.

Growth hormone and insulin-like growth factor 1 affect the severity of Graves' disease

Graves' disease, the most common form of hyperthyroidism in iodine-replete countries, is associated with the presence of immunoglobulins G (IgGs) that are responsible for thyroid growth and hyperfunction. In this article, we report the unusual case of a patient with acromegaly and a severe form of Graves' disease. Here, we address the issue concerning the role of growth hormone (GH) and insulin-like growth factor 1 (IGF1) in influencing thyroid function. Severity of Graves' disease is exacerbated by coexistent acromegaly and both activity indexes and symptoms and signs of Graves' disease improve after the surgical remission of acromegaly. We also discuss by which signaling pathways GH and IGF1 may play an integrating role in regulating the function of the immune system in Graves' disease and synergize the stimulatory activity of Graves' IgGs.

LEARNING POINTS

Clinical observations have demonstrated an increased prevalence of euthyroid and hyperthyroid goiters in patients with acromegaly.The coexistence of acromegaly and Graves' disease is a very unusual event, the prevalence being <1%.Previous in vitro studies have showed that IGF1 synergizes the TSH-induced thyroid cell growth-activating pathways independent of TSH/cAMP/PKA cascade.We report the first case of a severe form of Graves' disease associated with acromegaly and show that surgical remission of acromegaly leads to a better control of symptoms of Graves' disease.

The Impact of Growth Hormone Therapy on the Apoptosis Assessment in CD34+ Hematopoietic Cells from Children with Growth Hormone Deficiency

Growth hormone (GH) modulates hematopoietic cell homeostasis and is associated with apoptosis control, but with limited mechanistic insights. Aim of the study was to determine whether GH therapeutic supplementation (GH-TS) could affect apoptosis of CD34+ cells enriched in hematopoietic progenitor cells of GH deficient (GHD) children. CD34+ cells from peripheral blood of 40 GHD children were collected before and in 3rd and 6th month of GH-TS and compared to 60 controls adjusted for bone age, sex, and pubertal development. Next, apoptosis assessment via different molecular techniques was performed. Finally, to comprehensively characterize apoptosis process, global gene expression profile was determined using genome-wide RNA microarray technology. Results showed that GH-TS significantly reduced spontaneous apoptosis in CD34+ cells (p < 0.01) and results obtained using different methods to detect early and late apoptosis in analyzed cells population were consistent. GH-TS was also associated with significant downregulation of several members of TNF-alpha superfamily and other genes associated with apoptosis and stress response. Moreover, the significant overexpression of cyto-protective and cell cycle-associated genes was detected. These findings suggest that recombinant human GH has a direct anti-apoptotic activity in hematopoietic CD34+ cells derived from GHD subjects in course of GH-TS.

Effects of Feeding Milk Replacer Ad Libitum or in Restricted Amounts for the First Five Weeks of Life on the Growth, Metabolic Adaptation, and Immune Status of Newborn Calves

The pre-weaning period is critical for calf health and growth, and intensive milk feeding programs may assist postnatal development by improving body growth and organ maturation. The aim of the present work was to study the effects of ad libitum milk replacer (MR) feeding on the growth, metabolic adaptation, health, and immune status of newborn calves. Twenty-eight newborn Holstein and Holstein x Charolais crossbred calves were fed ad libitum (ADLIB) or in restricted amounts (6 liters per day; RES) during the first five weeks of life. The MR intake in the ADLIB treatment was gradually reduced at weeks 6 and 7, and all calves then received 6 liters of MR per day until day 60. Blood samples were collected to measure the plasma concentrations of metabolites, insulin, insulin-like growth factor (IGF)-I and IGF binding proteins (IGFBP), immunoglobulins, and acute phase proteins. The expression of mRNA associated with both the somatotropic axis and gluconeogenic enzymes was measured in the liver on day 60. Intensive feeding improved MR intake and growth in ADLIB without influencing concentrate intake. Carcass weight, perirenal fat, and muscle mass were greater in ADLIB. Plasma concentrations of glucose, triglycerides, insulin, and IGF-I were greater, whereas plasma concentrations of β-hydroxybutyrate, total protein, albumin, urea, IGFBP-2 and -4, and fibrinogen were lower at distinct time points in ADLIB. The hepatic mRNA expression of cytosolic phosphoenolpyruvate carboxykinase was greater in ADLIB. Most metabolic and endocrine differences occurred during the MR feeding period, but a slightly greater concentrate intake was associated with increased plasma IGF-I and insulin at the end of the study. The immune and health status of the calves were not affected by MR feeding. However, increased plasma fibrinogen in the RES group suggested differences in the acute phase response.

Clinical and molecular diagnosis of a cartilage-hair hypoplasia with IGF-1 deficiency

Cartilage-hair hypoplasia syndrome (CHH) is a rare autosomal recessive condition characterized by metaphyseal chondrodysplasia and characteristic hair, together with a myriad of other symptoms, being most common immunodeficiency and gastrointestinal complications. A 15-year-old Mexican male initially diagnosed with Hirschsprung disease and posterior immunodeficiency, presents to our department for genetic and complementary evaluation for suspected CHH. Physical, biochemical, and genetic studies confirmed CHH together with IGF-1 deficiency. For this reason, we propose IGF-1 replacement therapy for its well-known actions on hematopoiesis, immune function and maturation, and metabolism. © 2016 Wiley Periodicals, Inc.

Infectious diseases and immunological responses in adult subjects with lifetime untreated, congenital GH deficiency

Growth hormone is important for the development and function of the immune system, but there is controversy on whether growth hormone deficiency is associated to immune disorders. A model of isolated growth hormone deficiency may clarify if the lack of growth hormone is associated with increased susceptibility to infections, or with an altered responsiveness of the immune system. We have studied the frequency of infectious diseases and the immune function in adults with congenital, untreated isolated growth hormone deficiency. In a cross-sectional study, 35 adults with isolated growth hormone deficiency due to a homozygous mutation in the growth hormone releasing hormone receptor gene and 31 controls were submitted to a clinical questionnaire, physical examination serology for tripanosomiasis, leishmaniasis, HIV, tetanus, hepatitis B and C, and serum total immunoglobulin G, M, E and A measurement. The immune response was evaluated in a subset of these subjects by skin tests and response to vaccination for hepatitis B, tetanus, and bacillus Calmette-Guérin. There was no difference between the groups in history of infectious diseases and baseline serology. Isolated growth hormone deficiency subjects had lower total IgG, but within normal range. There was no difference in the response to any of the vaccinations or in the positivity to protein Purified Derived, streptokinase or candidin. Adult untreated isolated growth hormone deficiency does not cause an increased frequency of infectious diseases, and does not alter serologic tests, but is associated with lower total IgG levels, without detectable clinical impact.

Thymus: the next (re)generation

As the primary site of T-cell development, the thymus plays a key role in the generation of a strong yet self-tolerant adaptive immune response, essential in the face of the potential threat from pathogens or neoplasia. As the importance of the role of the thymus has grown, so too has the understanding that it is extremely sensitive to both acute and chronic injury. The thymus undergoes rapid degeneration following a range of toxic insults, and also involutes as part of the aging process, albeit at a faster rate than many other tissues. The thymus is, however, capable of regenerating, restoring its function to a degree. Potential mechanisms for this endogenous thymic regeneration include keratinocyte growth factor (KGF) signaling, and a more recently described pathway in which innate lymphoid cells produce interleukin-22 (IL-22) in response to loss of double positive thymocytes and upregulation of IL-23 by dendritic cells. Endogenous repair is unable to fully restore the thymus, particularly in the aged population, and this paves the way toward the need for exogenous strategies to help regenerate or even replace thymic function. Therapies currently in clinical trials include KGF, use of the cytokines IL-7 and IL-22, and hormonal modulation including growth hormone administration and sex steroid inhibition. Further novel strategies are emerging in the preclinical setting, including the use of precursor T cells and thymus bioengineering. The use of such strategies offers hope that for many patients, the next regeneration of their thymus is a step closer.

Leukocyte IGF-1 receptor expression during muscle recovery

INTRODUCTION

The insulin-like growth factor 1 (IGF-1) system plays a central role in anabolic cellular processes. Recently, a regulatory role of IGF-1 in the immune response for muscle repair has been suggested, but how it modulates the inflammatory process is largely unknown. We evaluated changes in leukocyte expression of IGF-1 receptors (IGF-1R) during recovery from resistance exercise to determine whether changes in the potential for IGF-1 interactions with leukocytes may mediate the role of IGF-1 in muscle repair.

METHODS

Twenty resistance-trained men (18-35 yr) performed resistance exercise followed by cold water immersion (CWI) or control treatment (CON) on three consecutive days. Blood was sampled at baseline (PRE), immediately (IP), 30 min (30P), 24 h (24H), and 48 h after (48H) exercise. Circulating IGF-1 was assayed, and IGF-1 receptor expression (CD221) on gated circulating leukocytes (monocytes, granulocytes, and lymphocytes) was measured by flow cytometry. Time and treatment effects were analyzed with ANCOVA.

RESULTS

Circulating IGF-1 significantly increased from PRE to IP as a result of resistance exercise, but no differences between CON and CWI were observed. Mean fluorescence intensity of CD221 on monocytes and granulocytes and percent of CD221+ granulocytes significantly increased at 30P (P < 0.000) and returned to preexercise levels by 24H. No treatment effects on monocytes or granulocytes were observed. On lymphocytes, mean fluorescence intensity of CD221+ significantly increased from PRE to 30P in CWI.

CONCLUSIONS

Changes in IGF-1 and its receptor on monocytes and granulocytes seem to be part of the mechanism that facilitates recovery from resistance exercise during earlier stages of muscle recovery. In addition, CWI seems to alter IGF-mediated responses on slower-acting lymphocytes, suggesting that its effects may be seen in later stages of muscle repair.

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.

Direct antiapoptotic effects of growth hormone are mediated by PI3K/Akt pathway in the chicken bursa of Fabricius

Growth hormone (GH) is expressed in several extra-pituitary tissues, including the primary and secondary lymphoid organs of the immune system. In birds, GH mRNA and protein expression show a specific developmental distribution pattern in the bursa of Fabricius (BF), particularly in epithelial and B cells. Changes in the bursal concentration and distribution of locally produced GH during ontogeny suggest it is involved in B cell differentiation and maturation, as well as in a functional survival role in this organ, which may be mediated by paracrine/autocrine mechanisms. Here, we analyzed the anti-apoptotic effect of GH in BF and the intracellular signaling pathways involved in this activity. Also, we studied if this effect was exerted directly by GH or mediated indirectly by IGF-I. Bursal cell cultures showed an important loss of their viability after 4h of incubation and a significant increase in apoptosis. However, treatment with 10nM GH or 40 nM IGF-I significantly increased B cell viability (16.7 ± 0.67% and 13.4 ± 1.12%, respectively) when compared with the untreated controls. In addition, the presence of apoptotic bodies (TUNEL) dramatically decreased (5.5-fold) after GH and IGF-I treatments, whereas co-incubation with anti-GH or anti-IGF-I, respectively, blocked their anti-apoptotic effect. Likewise, both GH and IGF-I significantly inhibited caspase-3 activity (by 40 ± 2.0%) in these cultures. However, the use of anti-IGF-I could not reverse the GH anti-apoptotic effects, thus indicating that these were exerted directly. The addition of 100 nM wortmannin (a PI3K/Akt inhibitor) blocked the GH protective effects. Also, GH stimulated (3-fold) the phosphorylation of Akt in bursal cells, and adding wortmannin or an anti-GH antibody inhibited this effect. Furthermore, GH was capable to stimulate (7-fold) the expression of Bcl-2. Taken together, these results indicate that the direct anti-apoptotic activity of GH observed in the chicken bursal B cell cultures might be mediated through the PI3K/Akt pathway.

Somatotrope GHRH/GH/IGF-1 axis at the crossroads between immunosenescence and frailty

Immunosenescence, characterized by complex modifications of immunity with age, could be related to frailty syndrome in elderly individuals, leading to an inadequate response to minimal aggression. Functional decline (i.e., the loss of ability to perform activities of daily living) is related to frailty and decreased physiological reserves and is a frequent outcome of hospitalization in older patients. Links between immunosenescence and frailty have been explored and 20 immunological parameters, including insulin-like growth factor-1 (IGF-1), thymopoeisis, and telomere length, were shown to be affected in elderly patients with functional decline. A strong relationship between IGF-1 and thymic ouput was evidenced. IGF-1, a mediator of growth hormone (GH), was subsequently shown to induce interleukin-7 secretion in cultured primary human thymic epithelial cells. We are exploring the stress hypothesis in which an acute stressor is used as the discriminator of frailty susceptibility. GH can counteract the deleterious immunosuppressive effects of stress-induced steroids. Under nonstress conditions, the immunosenescent system preserves physiological responses, while under stress conditions, the combination of immunosenescence and a defect in the somatotrope axis might lead to functional decline.

Insulin-like growth factors and related proteins in plasma and cerebrospinal fluids of HIV-positive individuals

Background

Clinically significant dysregulation of the insulin-like growth factor (IGF) family proteins occurs in HIV-infected individuals, but the details including whether the deficiencies in IGFs contribute to CNS dysfunction are unknown.

Methods

We measured the levels of IGF1, IGF2, IGFBP1, IGFBP2, and IGF2 receptor (IGF2R) in matching plasma and cerebrospinal fluid (CSF) samples of 107 HIV+ individuals from CNS HIV Antiretroviral Therapy Effects Research (CHARTER) and analyzed their associations with demographic and disease characteristics, as well as levels of several soluble inflammatory mediators (TNFα, IL-6, IL-10, IL-17, IP-10, MCP-1, and progranulin). We also determined whether IGF1 or IGF2 deficiency is associated with HIV-associated neurocognitive disorder (HAND) and whether the levels of soluble IGF2R (an IGF scavenging receptor, which we also have found to be a cofactor for HIV infection in vitro) correlate with HIV viral load (VL).

Results

There was a positive correlation between the levels of IGF-binding proteins (IGFBPs) and those of inflammatory mediators: between plasma IGFBP1 and IL-17 (β coefficient 0.28, P = 0.009), plasma IGFBP2 and IL-6 (β coefficient 0.209, P = 0.021), CSF IGFBP1 and TNFα (β coefficient 0.394, P < 0.001), and CSF IGFBP2 and TNF-α (β coefficient 0.14, P < 0.001). As IGFBPs limit IGF availability, these results suggest that inflammation is a significant factor that modulates IGF protein expression/availability in the setting of HIV infection. However, there was no significant association between HAND and the reduced levels of plasma IGF1, IGF2, or CSF IGF1, suggesting a limited power of our study. Interestingly, plasma IGF1 was significantly reduced in subjects on non-nucleoside reverse transcriptase inhibitor-based antiretroviral therapy (ART) compared to protease inhibitor-based therapy (174.1 ± 59.8 vs. 202.8 ± 47.3 ng/ml, P = 0.008), suggesting a scenario in which ART regimen-related toxicity can contribute to HAND. Plasma IGF2R levels were positively correlated with plasma VL (β coefficient 0.37, P = 0.021) and inversely correlated with current CD4+ T cell counts (β coefficient −0.04, P = 0.021), supporting our previous findings in vitro.

Conclusions

Together, these results strongly implicate (1) an inverse relationship between inflammation and IGF growth factor availability and the contribution of IGF deficiencies to HAND and (2) the role of IGF2R in HIV infection and as a surrogate biomarker for HIV VL.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0288-6) contains supplementary material, which is available to authorized users.

Extrapituitary growth hormone and growth?

While growth hormone (GH) is obligatory for postnatal growth, it is not required for a number of growth-without-GH syndromes, such as early embryonic or fetal growth. Instead, these syndromes are thought to be dependent upon local growth factors, rather than pituitary GH. The GH gene is, however, also expressed in many extrapituitary tissues, particularly during early development and extrapituitary GH may be one of the local growth factors responsible for embryonic or fetal growth. Moreover, as the expression of the GH receptor (GHR) gene mirrors that of GH in extrapituitary tissues the actions of GH in early development are likely to be mediated by local autocrine or paracrine mechanisms, especially as extrapituitary GH expression occurs prior to the ontogeny of pituitary somatotrophs or the appearance of GH in the circulation. The extrapituitary expression of pituitary somatotrophs or the appearance of GH in the circulation. The extrapituitary expression of GH in embryos has also been shown to be of functional relevance in a number of species, since the immunoneutralization of endogenous GH or the blockade of GH production is accompanied by growth impairment or cellular apoptosis. The extrapituitary expression of the GH gene also persists in some central and peripheral tissues postnatally, which may reflect its continued functional importance and physiological or pathophysiological significance. The expression and functional relevance of extrapituitary GH, particularly during embryonic growth, is the focus of this brief review.

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.

Secretagogue induction of GH release in QNR/D cells: prevention of cell death

Retinal ganglion cells (RGCs) in the chick embryonic neural retina are extrapituitary sites of growth hormone (GH) synthesis and release. The regulation of GH secretion by these cells is largely unknown, although we recently discovered several of the hypothalamic releasing factors involved in pituitary GH regulation (including GH-releasing hormone (GHRH) and thyrotropin releasing hormone, TRH) to be present in the cytoplasm of immortalized quail RGCs (QNR/D cells). QNR/D cells may therefore provide an experimental model for studies on GH regulation in the chick neural retina. The possibility that GHRH and TRH might stimulate GH secretion in QNR/D cells was therefore investigated. Both peptides acutely depleted the GH content of the QNR/D cells, as demonstrated by immunocytochemistry and ELISA, whilst increasing the GH content in incubation media. Both peptides also increased the immunochemical and ELISA content of the QNR/D cells and the content of GH in the incubation media after long-term incubation. Cell survival, determined by metabolic activity of the QNR/D cells and by TUNEL-labeling, was reduced when the endogenous GH content was reduced by GH immunoneutralization, even in the presence of exogenous GHRH or TRH. Cell survival was also reduced when endogenous GHRH was blocked by GHRH immunoneutralization, although the immunoneutralization of endogenous TRH did not affect QNR/D cell survival. In summary, these results demonstrate secretagogue actions of exogenous GHRH and TRH on the secretion of GH from QNR/D cells. They also suggest that endogenous GHRH, but not endogenous TRH, prevents cell death by increasing endogenous GH secretion in QNR/D cells.

Growth hormone (GH) and GH-releasing hormone (GHRH): Co-localization and action in the chicken testis

Growth hormone (GH) gene expression is not confined to the pituitary gland and occurs in many extrapituitary tissues, including the chicken testis. The regulation and function of GH in extrapituitary tissues is, however, largely unknown. The possibility that chicken testicular GH might be regulated by GH-releasing hormone (GHRH), as in the avian pituitary gland, was investigated in the present study. GHRH co-localized with GH in the germinal epithelium and in interstitial zones within the chicken testes, particularly in the spermatogonia and spermatocytes. In testicular cell cultures, exogenous human GHRH1-44 induced (at 1, 10 and 100nM) a dose-related increase in GH release. Western blot analysis showed a heterogeneous pattern in the GH moieties released during GHRH stimulation. 26kDa monomer GH was the most abundant moiety under basal conditions, but 15 and 17kDa isoforms were more abundant after GHRH stimulation. GHRH treatment also increased the abundance of PCNA (proliferating cell nuclear antigen) immunoreactivity in the testes. This may have been GH-mediated, since exogenous GH similarly increased the incorporation of ((3)H)-thymidine into cultured testicular cells and increased their metabolic activity, as determined by increased MTT reduction. Furthermore, GH and GHRH immunoneutralization blocked GHRH-stimulated proliferative activity. In summary, these results indicate that GHRH stimulates testicular GH secretion in an autocrine or paracrine manner. Data also demonstrate proliferative actions of GHRH on testicular cell number and suggest that this action is mediated by local GH production.

Interaction of the endocrine system with inflammation: a function of energy and volume regulation

During acute systemic infectious disease, precisely regulated release of energy-rich substrates (glucose, free fatty acids, and amino acids) and auxiliary elements such as calcium/phosphorus from storage sites (fat tissue, muscle, liver, and bone) are highly important because these factors are needed by an energy-consuming immune system in a situation with little or no food/water intake (sickness behavior). This positively selected program for short-lived infectious diseases is similarly applied during chronic inflammatory diseases. This review presents the interaction of hormones and inflammation by focusing on energy storage/expenditure and volume regulation. Energy storage hormones are represented by insulin (glucose/lipid storage and growth-related processes), insulin-like growth factor-1 (IGF-1) (muscle and bone growth), androgens (muscle and bone growth), vitamin D (bone growth), and osteocalcin (bone growth, support of insulin, and testosterone). Energy expenditure hormones are represented by cortisol (breakdown of liver glycogen/adipose tissue triglycerides/muscle protein, and gluconeogenesis; water retention), noradrenaline/adrenaline (breakdown of liver glycogen/adipose tissue triglycerides, and gluconeogenesis; water retention), growth hormone (glucogenic, lipolytic; has also growth-related aspects; water retention), thyroid gland hormones (increase metabolic effects of adrenaline/noradrenaline), and angiotensin II (induce insulin resistance and retain water). In chronic inflammatory diseases, a preponderance of energy expenditure pathways is switched on, leading to typical hormonal changes such as insulin/IGF-1 resistance, hypoandrogenemia, hypovitaminosis D, mild hypercortisolemia, and increased activity of the sympathetic nervous system and the renin-angiotensin-aldosterone system. Though necessary during acute inflammation in the context of systemic infection or trauma, these long-standing changes contribute to increased mortality in chronic inflammatory diseases.

Neuroendocrine immunoregulation in multiple sclerosis

Currently, it is generally accepted that multiple sclerosis (MS) is a complex multifactorial disease involving genetic and environmental factors affecting the autoreactive immune responses that lead to damage of myelin. In this respect, intrinsic or extrinsic factors such as emotional, psychological, traumatic, or inflammatory stress as well as a variety of other lifestyle interventions can influence the neuroendocrine system. On its turn, it has been demonstrated that the neuroendocrine system has immunomodulatory potential. Moreover, the neuroendocrine and immune systems communicate bidirectionally via shared receptors and shared messenger molecules, variously called hormones, neurotransmitters, or cytokines. Discrepancies at any level can therefore lead to changes in susceptibility and to severity of several autoimmune and inflammatory diseases. Here we provide an overview of the complex system of crosstalk between the neuroendocrine and immune system as well as reported dysfunctions involved in the pathogenesis of autoimmunity, including MS. Finally, possible strategies to intervene with the neuroendocrine-immune system for MS patient management will be discussed. Ultimately, a better understanding of the interactions between the neuroendocrine system and the immune system can open up new therapeutic approaches for the treatment of MS as well as other autoimmune diseases.

Growth hormone prevents the development of autoimmune diabetes

Evidence supports a relationship between the neuroendocrine and the immune systems. Data from mice that overexpress or are deficient in growth hormone (GH) indicate that GH stimulates T and B-cell proliferation and Ig synthesis, and enhances maturation of myeloid progenitor cells. The effect of GH on autoimmune pathologies has nonetheless been little studied. Using a murine model of type 1 diabetes, a T-cell-mediated autoimmune disease characterized by immune cell infiltration of pancreatic islets and destruction of insulin-producing β-cells, we observed that sustained GH expression reduced prodromal disease symptoms and eliminated progression to overt diabetes. The effect involves several GH-mediated mechanisms; GH altered the cytokine environment, triggered anti-inflammatory macrophage (M2) polarization, maintained activity of the suppressor T-cell population, and limited Th17 cell plasticity. In addition, GH reduced apoptosis and/or increased the proliferative rate of β-cells. These results support a role for GH in immune response regulation and identify a unique target for therapeutic intervention in type 1 diabetes.

Low-dose growth hormone for 40 weeks induces HIV-1-specific T cell responses in patients on effective combination anti-retroviral therapy

Recombinant human growth hormone (rhGH) administered to combination anti-retroviral therapy (cART)-treated human immunodeficiency virus-1 (HIV-1)-infected individuals has been found to reverse thymic involution, increase total and naive CD4 T cell counts and reduce the expression of activation and apoptosis markers. To date, such studies have used high, pharmacological doses of rhGH. In this substudy, samples from treated HIV-1(+) subjects, randomized to receive either a physiological dose (0·7 mg) of rhGH (n = 21) or placebo (n = 15) daily for 40 weeks, were assessed. Peptide-based enzyme-linked immunospot (ELISPOT) assays were used to enumerate HIV-1-specific interferon (IFN)-γ-producing T cells at baseline and week 40. Individuals who received rhGH demonstrated increased responses to HIV-1 Gag overlapping 20mer and Gag 9mer peptide pools at week 40 compared to baseline, whereas subjects who received placebo showed no functional changes. Subjects with the most robust responses in the ELISPOT assays had improved thymic function following rhGH administration, as determined using CD4(+) T cell receptor rearrangement excision circle (TREC ) and thymic density data from the original study. T cells from these robust responders were characterized further phenotypically, and showed decreased expression of activation and apoptosis markers at week 40 compared to baseline. Furthermore, CD4 and CD8 T cell populations were found to be shifted towards an effector and central memory phenotype, respectively. Here we report that administration of low-dose rhGH over 40 weeks with effective cART resulted in greater improvement of T lymphocyte function than observed with cART alone, and provide further evidence that such an approach could also reduce levels of immune activation.

Induction of genes encoding NADPH oxidase components and activation of IFN regulatory factor-1 by prolactin in fish macrophages

The role played by prolactin (PRL) in fish immunity is scant. We report here that stimulation of the Atlantic salmon monocytic cell line SHK-1 with native salmon PRL resulted in activation of the respiratory burst and induction of the expression of the genes encoding the phagocyte NADPH oxidase components p47phox, p67phox and gp91phox, and the transcription factor IFN regulatory factor-1 (IRF-1). Interestingly, the pharmacologic inhibition of the Jak/Stat signaling pathway with AG490 blocked reactive oxygen species (ROS) production, and the induction of genes encoding the NADPH oxidase components and IRF-1 in PRL-activated SHK-1 cells. In addition, PRL promoted the phosphorylation of Stat and induced the DNA binding activity of IRF-1. These results, together with the presence of several consensus target motifs for Stat and IRF-1 in the promoter of the tilapia p47phox gene, suggest that PRL regulates p47phox gene expression in fish through the activation of these two key transcription factors. Taken together, our results demonstrate that PRL induces the expression of the genes encoding the major phagocyte NADPH oxidase components and ROS production in fish macrophages via the JAK2/Stat/IRF-1 signaling pathway.

Human conditions of insulin-like growth factor-I (IGF-I) deficiency

Insulin-like growth factor I (IGF-I) is a polypeptide hormone produced mainly by the liver in response to the endocrine GH stimulus, but it is also secreted by multiple tissues for autocrine/paracrine purposes. IGF-I is partly responsible for systemic GH activities although it possesses a wide number of own properties (anabolic, antioxidant, anti-inflammatory and cytoprotective actions). IGF-I is a closely regulated hormone. Consequently, its logical therapeutical applications seems to be limited to restore physiological circulating levels in order to recover the clinical consequences of IGF-I deficiency, conditions where, despite continuous discrepancies, IGF-I treatment has never been related to oncogenesis. Currently the best characterized conditions of IGF-I deficiency are Laron Syndrome, in children; liver cirrhosis, in adults; aging including age-related-cardiovascular and neurological diseases; and more recently, intrauterine growth restriction. The aim of this review is to summarize the increasing list of roles of IGF-I, both in physiological and pathological conditions, underlying that its potential therapeutical options seem to be limited to those proven states of local or systemic IGF-I deficiency as a replacement treatment, rather than increasing its level upper the normal range.

Growth Hormone and Insulin-like Growth Factor 1: New Endocrine Therapies in Cardiology?

The hormones growth hormone (GH) and insulin-like growth factor 1 (IGF-1) play a dominant role in whole body growth and metabolism. This is reflected in the use of human GH (hGH) in GH-deficient children to stimulate growth and in GH-deficient adults to reduce visceral fat mass. Recent data suggest that hGH may improve cardiac function in patients with heart failure, so there is current interest in methods to raise GH-IGF levels, including the testing of agents that release GH from the pituitary, administering IGF-1, and most recently, long-acting formulations of hGH. It is hoped that this ongoing integration of cardiology and endocrinology will uncover the pathophysiology of some cardiovascular diseases and yield new treatments based on the hormones of the GH axis. (Trends Cardiovasc Med 1997;7:264-268). © 1997, Elsevier Science Inc.