Effects of growth hormone and insulin-like growth factor I on T- and B-lymphocytes and immune function

The protection role of human growth hormone on skin cells following ultraviolet B exposure

BACKGROUND

Ultraviolet-B (UVB) radiation is the leading environmental cause of skin damage and photoaging. The epidermis and dermis layers of the skin mainly absorb UVB. UVB stimulates apoptosis, cell cycle arrest, generation of reactive oxygen species, and degradation of collagen and elastin fibers.

OBJECTIVE

This study investigated the potential of human growth hormone (hGH) in protecting the skin fibroblasts and keratinocytes (HFFF-2 and HaCaT cell lines) from UVB-induced damage.

METHODS

The MTT assay was performed to evaluate UVB-induced mitochondrial damage via assessing the mitochondrial dehydrogenase activity, and flow cytometry was carried out to investigate the effects of UVB and hGH on the cell cycle and apoptosis of UVB-irradiated cells. In addition, the fold change mRNA expression levels of Type I collagen and elastin in HFFF-2 cells were evaluated using the qRT-PCR method following UVB exposure.

RESULTS

We observed that treatment of cells with hGH before UVB exposure inhibited UVB-induced loss of mitochondrial dehydrogenase activity, apoptosis, and sub-G1 population formation in both cell lines. We also found that hGH-treated HFFF-2 cells showed up-regulated mRNA expression of Type I collagen, elastin, and IGF-1 in response to UVB irradiation.

CONCLUSION

These findings suggest hGH as a potential anti-UVB compound that can protect skin cells from UVB-induced damage. Our findings merit further investigation and can be used to better understand the role of hGH in skin photoaging.

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.

Hormone replacement therapy in children with growth hormone deficiency: impact on immune profile

Growth hormone (GH) may influence the immune system. The aim of this study was to assess the immune profile after treatment with GH in pre-pubertal children with a deficiency of this hormone. The study was carried out in two phases. Two groups were included in the first phase: group A) children treated with GH; group B) untreated children, prior to starting treatment. In the second phase, group B children were assessed 6 months after starting treatment. In the first phase, groups A and B were compared (case-control study). In the second phase, group B was compared in terms of baseline and final times (before and after study). We analysed: humoral immunity (immunoglobulin (Ig)A, IgG, IgM, C1 inhibitor, C3, and C4) and cell-mediated immunity (CD3+, CD4+, CD8+, CD4+/CD8+, CD19+ lymphocytes, and natural killer (NK) cells). Insulin-like growth factor 1 (IGF-1) and insulin-like growth factor-binding protein 3 (IGFBP-3) were also determined. In the first phase, CD3+, CD4+, CD19+, and NK cells and CD4+/CD8+ were greater in the treated group. CD8+ was lower in this group. No variations were seen in immunoglobulins and the complement between both groups. There were no changes to the complement in either of the two phases. In the second phase, untreated patients were assessed after 6 months of treatment. When comparing the baseline and final immune profiles, a statistically significant decrease in IgG and IgM was observed, and an increase of IGF-1 levels and monocytes. In conclusion, our study shows changes in the cellular and humoral immune profiles in children with GH deficiency who were treated.

Identification of Haptoglobin as a Readout of rhGH Therapy in GH Deficiency

BACKGROUND

GH deficiency (GHD) is characterized by a cluster of cardiovascular risk factors and subtle inflammation. We aimed to demonstrate, through a proteomic approach, molecules directly modulated by GHD and involved in the inflammatory state.

METHODS

Ten children with isolated GHD were studied before and after 1 year of treatment with rhGH and compared with 14 matched controls. A two-dimensional electrophoresis plasma proteomics analysis was performed at baseline and after GH treatment to identify the top molecules modulated by GH. In vitro studies on human hepatoma (HepG2) cells were performed to validate the data.

RESULTS

Twelve of 20 proteomic spots were predicted to be isoforms α and β of haptoglobin (Hp) and confirmed by liquid chromatography tandem mass spectrometry and Western immunoblot analyses. Hp levels were higher in patients with GHD than controls at baseline (P < 0.001) and were reduced following GH treatment (P < 0.01). In HepG2 cells, both GH and IGF-1 were able to downregulate IL-6-induced Hp secretion. Moreover, Hp secretion was restored in pegvisomant-treated HepG2 cells.

CONCLUSIONS

Hp is a molecule acting in the inflammatory state of GHD and a possible biomarker for GH treatment. Nevertheless, the contribution of other factors and the molecular pathways involved in the GH downregulation of Hp remain to be clearly defined.

Plasma levels of Th1/Th2 Type Cytokine are Associated with Change of Prolactin and GH/IGF-I in Hemodialysis Patients

Patients undergoing chronic hemodialysis (HD) have an impaired immune system involving both B and T cell-mediated immune responses. Since T helper type 1 (Th1) and type 2 (Th2) cytokines are implicated in regulating the immune responses, while the pituitary hormones, prolactin (PRL) and growth hormone (GH) are known to be involved in the regulation of the immune response, all of them may, therefore, be involved in impaired status. The aims of the present study were to estimate the serum concentrations of Th1-Th2 cytokine, GH, insulin-like growth factor-I (IGF-I) and PRL, and to determine whether there are any correlations between the release of T-cell cytokines and disturbance of hormones in a group of patients on maintenance hemodialysis (MHD). The study included 35 HD patients (23 males and 12 females, mean age 56.8±12.8 years) and a control group of 20 age-matched healthy subjects. Baseline serum concentrations of GH/IGF-I, PRL, IL-2, sIL-2R, IFN-γ, IL-4 and IL-10 were measured in all patients and control subjects. Our results demonstrate that the fasting serum concentration of IGF-I, PRL, sIL-2R and Th1-type cytokine, including IL-2 and IFN-γ, were significantly higher in HD patients compared to the healthy subjects. GH and Th2-type cytokine including IL-4 and IL-10 levels were slightly reduced, but no significant differences were observed between HD patients and the control group. In the group of HD patients, PRL correlated directly with IFN-γ and correlated inversely with IL-10; IFN-γ correlated inversely with IL-4; and GH also correlated inversely with IGF-I and IL-4. However, IGF-I correlated directly with IL-2 and IL-10. These data suggest that the Th1/Th2 imbalance in HD patients with an increase of Th1 type cytokines, associated with the altered GH/IGF-I axis and prolactin and immuno-endocrine dysfunction, probably plays a role in an impaired immune system in HD patients.

Growth hormone decreases visceral fat and improves cardiovascular risk markers in women with hypopituitarism: a randomized, placebo-controlled study

CONTEXT

Data regarding gender-specific efficacy of GH on critical endpoints are lacking. There are no randomized, placebo-controlled studies of physiological GH therapy solely in women.

OBJECTIVE

Our objective was to determine the effects of physiological GH replacement on cardiovascular risk markers and body composition in women with GH deficiency (GHD).

DESIGN

This was a 6-month, randomized, placebo-controlled, double-blind study.

SETTING

The study was conducted at the General Clinical Research Center.

STUDY PARTICIPANTS

43 women with GHD due to hypopituitarism were included in the study.

INTERVENTION

Study participants were randomized to receive GH (goal mid-normal serum IGF-1) or placebo.

MAIN OUTCOME MEASURES

Cardiovascular risk markers, including high-sensitivity C-reactive protein, tissue plasminogen activator, and body composition, including visceral adipose tissue by cross-sectional computed tomography, were measured.

RESULTS

Mean daily GH dose was 0.67 mg. The mean IGF-1 sd score increased from -2.5 +/- 0.3 to -1.4 +/- 0.9 (GH) (P < 0.0001 vs. placebo). High-sensitivity C-reactive protein decreased by 38.2 +/- 9.6% (GH) vs.18.2 +/- 6.0% (placebo) (P = 0.03). Tissue plasminogen activator and total cholesterol decreased, and high-density lipoprotein increased. Homeostasis model assessment-insulin resistance and other markers were unchanged. Body fat decreased [-5.1 +/- 2.0 (GH) vs. 1.9 +/- 1.0% (placebo); P = 0.002] as did visceral adipose tissue [-9.0 +/- 5.9 (GH) vs. 4.3 +/- 2.7% (placebo); P = 0.03]. Change in IGF-1 level was inversely associated with percent change in visceral adipose tissue (r = -0.61; P = 0.002), total body fat (r = -0.69; P < 0.0001), and high-sensitivity C-reactive protein (r = -0.51; P = 0.003).

CONCLUSIONS

Low-dose GH replacement in women with GHD decreased total and visceral adipose tissue and improved cardiovascular markers, with a relatively modest increase in IGF-1 levels and without worsening insulin resistance.

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.

Enhancement of Mucosal Immune Responses in Chickens by Oral Administration of Cysteamine

Somatostatin, a tetradecapeptide originally isolated from the hypothalamus, can exert an inhibitory effect on the secretion of growth hormone by the anterior pituitary gland. In addition to endocrine organs, somatostatin is also present in the digestive tract and immune organs. In lymphoid tissues, somatostatin appears to play a role in the modulation of the immune response. Cysteamine (CS) is a sulfhydryl reducing agent that is known as a depletory agent of somatostatin. To evaluate its effects on chicken mucosal immune responses, CS was administrated orally to 1-wk-old broilers (40 mg/kg) that were immunized orally with Newcastle disease attenuated vaccine (NDV). The number of IgA-positive cells and intestinal intraepithelial lymphocytes (iIEL) in duodenum and jejunum were examined at 3-, 5-, and 7-wk posttreatment and immunization. The number of somatostatin-positive cells and relative amounts of somatostatin mRNA were also examined in the duodenum. The number of somatostatin-positive cells in the duodenum was reduced (P < 0.05) after CS treatment. In broilers receiving CS and NDV treatment (CS+NDV) the level of IgA-positive cells and iIEL in the duodenum and jejunum was increased (P < 0.05) at 3 and 5 wk posttreatment. The expression of somatostatin mRNA increased (P < 0.05) compared with that of the control group at 5 wk after immunization in broilers receiving CS+NDV or NDV alone. The results suggest that CS can induce proliferation and differentiation of IgA-positive cells and iIEL in the intestinal mucosa of chickens by reducing the number of somatostatin-positive cells.

Growth hormone (GH)-induced reconstitution of CD8+ CD28+ T lymphocytes in a rare case of severe lymphopenia associated with Juvenile Haemochromatosis and Turner's syndrome

This paper describes a rare case of Turner's syndrome associated with Juvenile Haemochromatosis and severe lymphopenia, followed-up for a period of 5 years. Because of the indication for treatment with growth hormone (GH), this case was observed as a model to analyse the effects of GH on growth, iron mobilization and lymphocyte reconstitution. For this purpose, a serial study of the T lymphocyte subpopulations CD4+, CD8+, CD8+ CD28+ and CD8+ CD28- was performed by immunophenotyping during the follow-up period. Besides the impact of both phlebotomy treatment and GH on the rapid growth and mobilization of 20.8 g of iron in 136 weeks, the most relevant observation was the finding of a significant expansion of CD8+ T lymphocytes expressing the costimulatory marker CD28 in the setting of the severe lymphopenia. These findings constitute new clinical evidence supporting the notion that the GH/IGF-1 system has an important role on the maintenance of T cell homeostasis in vivo, and that GH may be regarded as a putative therapeutic agent in T lymphocyte reconstitution.

Increased Interleukin-6 levels in pituitary-deficient patients are independently related to their carotid intima-media thickness

OBJECTIVE

Increased cardiovascular morbidity and mortality has been observed in patients with pituitary deficiency and untreated growth hormone deficiency (GHD). We investigated peripheral inflammatory and fibrinolytic markers and their associations with arterial intima-media thickness (IMT) in GHD.

DESIGN

Cross-sectional study.

PATIENTS

Thirty-four patients with GHD, but without cardiovascular disease, were compared to healthy controls matched for age, sex, body mass index (BMI) and smoking habits.

MEASUREMENTS

IMT of the common carotid artery, C-reactive protein (CRP), interleukin-6 (IL-6), fibrinogen, plasminogen activator inhibitor-1 (PAI-1) activity and tissue plasminogen activator antigen (tPA-ag) were measured.

RESULTS

Median IL-6 concentrations were increased by 208% and 248% in GHD patients compared to BMI-matched and nonobese controls, respectively. Median CRP and tPA-ag levels were increased by 237% and 167% in patients compared to nonobese controls, but not significantly different compared to BMI-matched controls. Plasma levels of fibrinogen and PAI-1 activity did not differ between groups. Age, low-density lipoprotein (LDL) cholesterol, tPA-ag and IL-6 were positively correlated, and IGF-I was negatively correlated to IMT in the patient group, but only age and IL-6 were independently related to IMT.

CONCLUSIONS

IL-6 concentrations were increased in GHD patients compared to controls and independently related to IMT in patients. This finding may help to explain the variance in IMT and the increased vascular morbidity and mortality in hypopituitary patients with GHD.

A dietary supplement abolishes age-related cognitive decline in transgenic mice expressing elevated free radical processes

We previously found that transgenic mice overexpressing growth hormone (TGM) have elevated and progressively increasing free radical processes in brain that strongly correlates with reduced survivorship. Young mature TGM, however, displayed vastly enhanced learning of an eight-choice cued maze and qualitatively different learning curves than normal controls. Here we document the age-related patterns in learning ability of TGM and normal mice. Learning appeared inferior in both genotypes of very young mice but TGM were confirmed to be superior to normal mice upon maturity. Older TGM, however, showed rapid age-related loss of their exceptional learning, whereas normal mice at 1 year of age showed little change. The cognitive decline of TGM was abolished by a complex "anti-aging" dietary supplement formulated to promote membrane and mitochondrial integrity, increase insulin sensitivity, reduce reactive oxygen and nitrogen species, and ameliorate inflammation. Results are discussed in the context of reactive oxygen and nitrogen species, long-term potentiation, learning, aging and neuropathology, based on known impacts of the growth hormone axis on the brain, and characteristics of TGM.

Growth hormone protects human lymphocytes from irradiation-induced cell death

1. Undesired effects of cancer radiotherapy mainly affect the hematopoietic system. Growth hormone (GH) participates in both hematopoiesis and modulation of the immune response. We report both r-hGH cell death prevention and restoration of secretory capacities of irradiated human peripheral blood lymphocytes (PBL) in vitro. 2. r-hGH induced cell survival and increased proliferation of irradiated cells. Western blot analysis indicated that these effects of GH were paralleled by increased expression of the antiapoptotic protein Bcl-2. 3. r-hGH restored mitogen-stimulated release of IL-2 by PBL. Preincubation of irradiated lymphocytes with the growth hormone receptor (GHR) antagonists B2036 and G120 K abrogated r-hGH-dependent IL-2 release. 4. These results demonstrate that r-hGH protects irradiated PBL from death in a specific, receptor-mediated manner. Such effect of r-hGH on PBL involves activation of the antiapoptotic gene bcl-2 and prevention of cell death, associated with preserved functional cell capacity. Finally, potential use of GH as an immunopotentiating agent could be envisioned during radiation therapy of cancer.

Growth negatively impacts the life span of mammals

A negative intraspecific relationship between growth and longevity was proposed in the early 20th century. Indeed, stunting the growth of rodents by restricting their food dramatically extended life span. Subsequently, however, the hypothesis that growth exacerbates aging rates fell into disfavor. Contributing to this was (a) the establishment of a positive relationship between body size and longevity interspecifically, (b) purported antiaging impacts of growth hormone, and (c) the fact that the longevity of even mature rodents that had completed growth was extended by dietary restriction. Furthermore, intraspecific analytical studies failed to provide any clear resolution. This article presents the first global analyses of maximal longevity versus maximum mature mass for laboratory rats and mice, based on a relatively comprehensive compilation of research across the 20th century. Peak body mass (which reflects juvenile growth rates) was negatively associated with longevity within both species. Proximal mechanisms for impacts of growth on longevity appear congruent with the free radical and immunological theories of aging.

No evidence of tumor growth stimulation in human tumors in vitro following treatment with recombinant human growth hormone

In a recent study we demonstrated that recombinant human growth hormone (r-hGH; Saizen) delayed tumor-induced cachexia in human tumor xenografts in vivo. Such a therapeutic effect could have a great impact in the supportive care of advanced cancer patients. Before large clinical studies are initiated possible growth stimulation should be excluded. This question was investigated in vitro in 20 human tumor models, which had been established in serial passage in nude mice. The effect of continuous exposure of r-hGH was investigated at dose levels ranging from 0.3 ng/ml up to 0.1 microg/ml in colorectal (n=2), gastric (n=1), non-small cell lung (n=4), small cell lung (n=1), mammary (n=3), ovarian (n=2), prostate (n=2) and renal cancers (n=2), and melanoma (n=3) using a modified Hamburger and Salmon clonogenic assay. The results show that there was neither tumor growth inhibition nor any evidence for tumor growth stimulation in any of the tumors studies. Therefore this preclinical study in 20 human tumor models indicated no direct risk for tumor growth enhancement.

Role of growth hormone receptor in HL-60 cell survival

Although it is presently well established that locally produced growth hormone (GH) plays a major role in the regulation of survival mechanisms in hemopoietic cells, the responsible mechanisms are poorly understood, and the involvement of the GH receptor (GHR) has not even been demonstrated to date. In this work we investigated the presence of GHR in the human promyelocytic leukemia cell line HL-60, as well as the ability of GH treatment to stimulate both GHR and survival signaling pathways downstream GHR. Our results demonstrate that (1) both GHR mRNA and GHR immunoreactivity are present in HL-60 cells; (2) GH treatment results in an increase in the phosphorylation of the GHR-associated Jak2 and Stat3 proteins, indicating the ability of the hormone to induce receptor activation; and (3) activation of GHR increases the activity of Akt, a serine/threonine kinase that plays a prominent role in the regulation of cell survival. Taken together, these results demonstrate that GHR activation promotes survival of HL-60 cells, thus suggesting that GH plays a major role in the regulation of cell survival in the hemopoietic system, via an autocrine/paracrine mechanism.

Growth hormone in immune reconstitution

Immune cell death or dysfunction is induced by HIV infection and results in an immunocompromised state. Newer treatments are able to control viral replication to prevent massive cytoreduction. Attention must now focus on therapies that will rapidly reconstitute the immune system to provide defense against future HIV attacks as well as opportunistic infections. In addition to increasing the rate of differentiation of myeloid and lymphoid precursors from marrow stem cells, ideal therapies should improve thymic function as well. Growth hormone (GH), a member of the hematopoietic cytokine superfamily and its receptors, is expressed in multiple sites within the immune system. GH has been shown to have a stimulatory effect on the function of thymic cells, as well as other immune cell types. In this paper, we consider the use of GH to reconstitute the immune system following cytoreduction due to HIV infection.

Insulin-like growth factor-1 (IGF-1) and growth hormone (GH) in immunity and inflammation

In recent years many efforts have been undertaken to elucidate the complex interactions between mediators of the endocrine system and the immune system. The main effector of growth hormone (GH) is insulin-like growth factor-1 (IGF-1), an endocrine mediator of growth and development under physiological conditions. Besides this important function, IGF-1 also plays a prominent role in the regulation of immunity and inflammation. This article will address the involvement of IGF-1 in innate as well as acquired immunity and host-defense. We also discuss the role of IGF-1 in the course of inflammatory disorders, including sepsis and sepsis-induced catabolism as well as degenerative arthritis. Based on recent insights, we finally examine the pathophysiological background, potential pitfalls and perspectives of IGF-1 suppletion therapy in these conditions.

General ageing and ovarian ageing

The age related decrease in female fertility is associated with a decrease in follicle numbers and oocyte quality. Meiotic division errors, mitochondrial DNA mutations and ageing itself have been suggested to play a part in the age associated reduction in oocyte quality. During the past decades several hypothesis have been proposed, trying to explain the underlying mechanisms. However, none of them is yet conclusive. This review will consider the main hypotheses regarding the age related reduction in oocyte quality. This will be reviewed together with recent results of studies analysing a possible relationship between ageing and ovarian ageing. On the basis of our own results and those presented in the literature, it is concluded that ovarian ageing may only be related to specific aspects of general ageing.

Insulin-like growth factor-1 (IGF-1) has a costimulatory effect on proliferation of committed progenitors derived from human umbilical cord CD34+ cells

The effects of insulin-like growth factor-1 (IGF-1) on highly enriched human umbilical cord CD34+ cells were investigated in vitro. CD34+ cells were cultured in serum-free medium containing stem cell factor (SCF), GM-CSF, and interleukin-3 (IL-3). Culture of CD34+ cells for one week in the presence of these cytokines resulted in a dose-dependent increase in total cell number. Addition of G-CSF together with SCF+IL-3+GM-CSF increased the proliferation of myelopoietic cells as determined by the number of cells expressing the myelomonocytic marker CD64 and the granulocytic marker CD15 without significantly altering the number of CD34+ cells in the cultures. In the presence of G-CSF, IGF-1 induced a dose-dependent increase in the total cell number and a moderate but significant increase in the percentages of CD15+, CD64+ cells with sustained CD34+ cell proliferation. We conclude that IGF-1 can enhance the in vitro proliferation of committed progenitor cells derived from umbilical cord CD34+ cells.