Growth hormone-induced stimulation of multilineage human hematopoiesis

Purification and Activity Evaluation of a Novel Thrombopoietin Mimetic Peptide

The emergence of thrombopoietin mimetic peptides presents a promising therapeutic strategy for addressing thrombocytopenia. This particular study aimed to establish a direct, expeditious, and efficient method for modifying and purifying a novel thrombopoietin mimetic peptide. Precursor proteins were subjected to modification utilizing three distinct fatty acids: C25H42O7N2, C39H66O15N4, and C41H70O15N4. Liquid chromatography analyses demonstrated that C41H70O15N4 yielded the most effective modification results. Mass spectrometry findings validated the correspondence between the theoretical and actual molecular weights of each sample. In vivo experiments conducted on normal mice showcased that the C41H70O15N4 modification group exhibited the highest platelet count, peaking at an impressive 5047 × 109/L. This count was approximately twice that of the peak platelet count observed in the dTMP group and four times higher than the control group. Pharmacokinetic investigations revealed that the C41H70O15N4 modification group displayed the lengthiest half-life among beagles, persisting for 128.5 h. This duration was approximately 28.5 times longer than that of the unmodified dTMP group. These findings underscore the effectiveness of the established C41H70O15N4 modification and purification method in preserving the biological activity of the thrombopoietin mimetic peptide. The novel thrombopoietin mimetic peptide showcased notable attributes of simplicity and cost-effectiveness, while also exhibiting a significant platelet-promoting effect and an extended half-life. Consequently, this novel peptide holds substantial significance for advancing the treatment of thrombocytopenia.

Intrathymic somatotropic circuitry: consequences upon thymus involution

Growth hormone (GH) is a classic pituitary-derived hormone crucial to body growth and metabolism. In the pituitary gland, GH production is stimulated by GH-releasing hormone and inhibited by somatostatin. GH secretion can also be induced by other peptides, such as ghrelin, which interacts with receptors present in somatotropic cells. It is well established that GH acts directly on target cells or indirectly by stimulating the production of insulin-like growth factors (IGFs), particularly IGF-1. Notably, such somatotropic circuitry is also involved in the development and function of immune cells and organs, including the thymus. Interestingly, GH, IGF-1, ghrelin, and somatostatin are expressed in the thymus in the lymphoid and microenvironmental compartments, where they stimulate the secretion of soluble factors and extracellular matrix molecules involved in the general process of intrathymic T-cell development. Clinical trials in which GH was used to treat immunocompromised patients successfully recovered thymic function. Additionally, there is evidence that the reduction in the function of the somatotropic axis is associated with age-related thymus atrophy. Treatment with GH, IGF-1 or ghrelin can restore thymopoiesis of old animals, thus in keeping with a clinical study showing that treatment with GH, associated with metformin and dehydroepiandrosterone, could induce thymus regeneration in healthy aged individuals. In conclusion, the molecules of the somatotrophic axis can be envisioned as potential therapeutic targets for thymus regeneration in age-related or pathological thymus involution.

Coupling Complete Blood Count and Steroidomics to Track Low Doses Administration of Recombinant Growth Hormone: An Anti-Doping Perspective

Growth Hormone (GH) under its human recombinant homologue (rhGH), may be abused by athletes to take advantage of its well-known anabolic and lipolytic properties; hence it is prohibited in sports by the World Anti-Doping Agency. Due to the rapid turnover of rhGH, anti-doping screening tests have turned to monitor two endocrine biomarkers (IGF-I and P-III-NP), but unfortunately, they show population-wise variability, limiting the identification rate of rhGH users. Previous studies have evidenced the numerous effects of GH on human physiology, especially in hematopoiesis and steroidogenesis. In this work, aiming to discover novel physiological rhGH biomarkers, we analyzed the complete blood count and the steroidomics profile of healthy, physically active, young males treated either with EPO + rhGH or EPO + placebo. The time-trends of these two physiological routes have been analyzed through geometric trajectory analysis (GTA) and OPLS-DA. Individuals supplemented with micro-doses of rhGH exhibited different leukopoietic and steroidal profiles compared to the control population, suggesting a role of the rhGH in both pathways. In the article, hypotheses on the observed differences are discussed according to the most recent literature and compared to results in animal models. The use of leukopoietic and steroidal biomarkers together with endocrine biomarkers (IGF-1 and P-III-NP) allows to correctly classify over 98% of samples with no false positives, miss-classifying only one single sample (false negative) over a total of 56; a promising result, if compared to the current rhGH detection strategies.

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.

Iron Homeostasis and Hepcidin Concentration in Patients With Acromegaly

Hepcidin is a protein responsible for maintaining iron (Fe) homeostasis. Data regarding the role of hepcidin in the pathomechanism of Fe balance disturbances associated with acromegaly (AG) are scarce. The aim of the study was to assess the impact of alterations in complete blood count parameters, Fe homeostasis, gonadal status and GH/IGF-1 on the level of hepcidin in AG patients. The study evaluated the differences in hepcidin concentration and iron homeostasis between patients newly diagnosed with AG in comparison to healthy control subjects (CS). We prospectively enrolled 25 adult patients newly diagnosed with AG and 25 healthy volunteers who served as CS. The level of hepcidin was measured using the Hepcidin 25 (bioactive) hs ELISA, which is a highly sensitive enzyme immunoassay for the quantitative in vitro diagnostic measurement (DRG Instruments GmbH, Germany). The median of hepcidin concentration in the serum of patients with AG was significantly lower 9.8 (6.2-18.2) ng/ml as compared to CS 21.3 (14.3-34.0) ng/ml (p = 0.003). In the AG group, a statistically significant negative correlation between hepcidin and IGF-1 (rho = -0.441) was observed. Our study demonstrated a decreased hepcidin level in AG patients in comparison to CS what may have a potentially protective effect against anemia through an increased bioavailability of Fe. Additionally, GH may have a positive direct or indirect effect on erythropoiesis. Further studies on larger patient groups are necessary in order to clarify the exact role of hepcidin in the regulation of erythropoiesis in the excess of GH/IGF-1.

Reversal of epigenetic aging and immunosenescent trends in humans

Epigenetic “clocks” can now surpass chronological age in accuracy for estimating biological age. Here, we use four such age estimators to show that epigenetic aging can be reversed in humans. Using a protocol intended to regenerate the thymus, we observed protective immunological changes, improved risk indices for many age‐related diseases, and a mean epigenetic age approximately 1.5 years less than baseline after 1 year of treatment (−2.5‐year change compared to no treatment at the end of the study). The rate of epigenetic aging reversal relative to chronological age accelerated from −1.6 year/year from 0–9 month to −6.5 year/year from 9–12 month. The GrimAge predictor of human morbidity and mortality showed a 2‐year decrease in epigenetic vs. chronological age that persisted six months after discontinuing treatment. This is to our knowledge the first report of an increase, based on an epigenetic age estimator, in predicted human lifespan by means of a currently accessible aging intervention.

Tissue regeneration: Impact of sleep on stem cell regenerative capacity

The circadian rhythm orchestrates many cellular functions, such as cell division, cell migration, metabolism and numerous intracellular biological processes. The physiological changes during sleep are believed to promote a suitable microenvironment for stem cells to proliferate, migrate and differentiate. These effects are mediated either directly by circadian clock genes or indirectly via hormones and cytokines. Hormones, such as melatonin and cortisol, are secreted in response to neural optic signals and act in harmony to regulate many biological functions during sleep. Herein, we correlate the effects of the main circadian genes on the expression of certain stem cell genes responsible for the regeneration of different tissues, including bone, cartilage, skin, and intestine. We also review the effects of different hormones and cytokines on stem cell activation or suppression and their relationship to the day/night cycle. The correlation of circadian rhythm with tissue regeneration could have implications in understanding the biology of sleep and tissue regeneration and in enhancing the efficacy and timing of surgical procedures.

Growth hormone and hematopoiesis: A retrospective analysis on a large cohort of children with growth hormone deficiency

OBJECTIVE

Few large-scale studies regarding the impact of GH deficiency (GHD) on hematopoiesis in children have been reported. Our aim was to investigate hematopoiesis indices in a large cohort of GHD children at diagnosis and during GH treatment (GHT) and any correlation with hormonal parameters.

DESIGN

Clinical and biochemical data of children with idiopathic GHD at diagnosis and annually up to 36 months of GHT were retrospectively evaluated. Overall, 255 children reached 12 months, 140 children 24 months and 86 children 36 months of follow-up during GHT.

RESULTS

At baseline, 18.4% of GHD children and 10.1% of controls showed normocytic anemia. GHD children showed lower hemoglobin (Hb) (p = 0.007), red blood cells (RBC) (p < 0.001) and hematocrit (Ht) (p = 0.001) than controls. During GHT, the percentage of anemic patients decreased from 18.4 to 5.4-3.5 and 4.6% after 12 (p = 0.001), 24 (p < 0.001) and 36 months (p < 0.001) of GHT, respectively. In both anemic and non-anemic patients, a significant increase in Hb (p < 0.001, <0.001 and 0.002), RBC (all p < 0.001) and Ht (all p < 0.001) was found after 12, 24 and 36 months of GHT. The Hb levels were significantly correlated with the GH peak after stimulation test (p < 0.001) at baseline and with IGF-I levels at 36 months of GHT (p = 0.002).

CONCLUSIONS

A significant improvement in erythropoiesis indices occurs during GHT, regardless of any previous presence of anemia.

Resident murine macrophage migration and phagocytosis are modulated by growth hormone

Growth hormone (GH) plays a physiological role in the immune system. In macrophages, GH enhances the production of hydrogen peroxide, superoxide anions, nitric oxide, cytokines, and chemokines, including interferon-γ and macrophage inflammatory protein-1α. However, some of the effects of GH stimulation on the biological functions of macrophages remain to be elucidated. Herein, we showed that in vivo GH treatment resulted in decreased expression of VLA-5 and VLA-6 integrins on the macrophage surface, accompanied by a reduction in macrophage adhesion to extracellular matrix (ECM) ligands, fibronectin, and laminin. Additionally, a decrease in macrophage adhesion to laminin was observed when the cells were treated in vitro with GH. In transwell migration assays, GH-treated macrophages showed increased migration after 6 h. Although in vitro GH treatment did not influence the phagocytic activity of macrophages, when the treatment was performed in vivo, peritoneal macrophages from GH-treated mice showed a higher percentage of phagocytosis and higher phagocytic capacity than cells from control animals. These results led us to analyse the role of insulin-like growth factor-1 (IGF-1), a GH stimulated factor, on macrophage phagocytosis. We observed an increase in phagocytic activity when J774 murine macrophages were treated with IGF-1 for 24 h. Our results revealed an important role for GH in resident macrophage migration and phagocytic activity. Specifically, we demonstrate that IGF-1 may be the GH stimulated factor that induces macrophage phagocytosis in vivo.

A Vulnerable Age for the Introduction of Solid Foods in Pediatric Acute Lymphoblastic Leukemia

BACKGROUND

There is little research concerning infant formula or the age at introduction to solid foods and pediatric acute lymphoblastic leukemia (ALL). The purpose of this case-control study was to estimate the association of age at introduction of solids and pediatric ALL.

METHODS

171 ALL cases aged 0-14 years were recruited at Texas Children's Cancer Center and matched on sex, age, and ethnicity to 342 population-based controls. Data were collected on infant feeding and known risk factors for ALL. Multivariable logistic regression was used to model the odds ratio of ALL by quartile of age at introduction of solids with the first/earliest quartile (0-4 months) as the reference group.

RESULTS

In adjusted models, the odds ratio of ALL among children in quartile 3 (7-9 months) was 4.08, 95% confidence interval (CI) 1.42-11.71; for children in quartile 4 (≥10 months) the odds ratio (OR) was 6.03, 95% CI 2.06-17.72. For each additional month of milk formula feeding, the OR of ALL was 1.16, 95% CI 1.08-1.25.

CONCLUSIONS

These results suggest a window when later introduction to solids is positively associated with ALL and recommend compliance with the American Academy of Pediatrics guidelines.

Long-term effects of growth hormone (GH) replacement therapy on hematopoiesis in a large cohort of children with GH deficiency

The aim of our prospective case-control study was to evaluate long-term effects of GH replacement therapy on erythrocytes parameters, leukocytes, and platelets numbers in a large cohort of children with isolated GH deficiency (GHD). Hemoglobin (Hb) concentration, hematocrit (Hct), mean corpuscular volume, mean corpuscular hemoglobin, red cell distribution width, number of erythrocytes, leukocytes, neutrophils, lymphocytes, monocytes and platelets, ferritin, and C-reactive protein were evaluated in 85 children with isolated GHD (10.20 ± 3.50 years) before and annually during the first 5 years of GH replacement therapy and in 85 healthy children age and sex comparable to patients during 5 years of follow-up. Compared with controls, GHD children at study entry showed lower Hb (-1.18 ± 0.87 vs. -0.40 ± 0.90 SDS, p < 0.0001), red cells number (-0.24 ± 0.81 vs. 0.25 ± 1.14 SDS, p < 0.0001), and Hct (-1.18 ± 0.86 vs. -0.68 ± 0.99 SDS, p < 0.0001). Twelve GHD patients (14 %) showed a normocytic anemia. GH therapy was associated with a significant increase in Hb, Hct, and red cells number which became all comparable to controls within the first 2 years of treatment. Moreover, hemoglobin levels normalized in all anemic GHD patients after 5 years of therapy. No difference between patients and controls was found in leukocytes and platelets numbers neither at baseline nor during the study. GHD in childhood is associated with an impairment of erythropoiesis which causes a normocytic anemia in a considerable percentage of patients. GH replacement therapy exerts a beneficial effect leading to a significant increase of erythrocytes parameters and recovery from anemia. Neither GHD nor GH replacement treatment exerts effects on leukocytes or platelets numbers.

The Role of the Multiple Hormonal Dysregulation in the Onset of "Anemia of Aging": Focus on Testosterone, IGF-1, and Thyroid Hormones

Anemia is a multifactorial condition whose prevalence increases in both sexes after the fifth decade of life. It is a highly represented phenomenon in older adults and in one-third of cases is "unexplained." Ageing process is also characterized by a "multiple hormonal dysregulation" with disruption in gonadal, adrenal, and somatotropic axes. Experimental studies suggest that anabolic hormones such as testosterone, IGF-1, and thyroid hormones are able to increase erythroid mass, erythropoietin synthesis, and iron bioavailability, underlining a potential role of multiple hormonal changes in the anemia of aging. Epidemiological data more consistently support an association between lower testosterone and anemia in adult-older individuals. Low IGF-1 has been especially associated with anemia in the pediatric population and in a wide range of disorders. There is also evidence of an association between thyroid hormones and abnormalities in hematological parameters under overt thyroid and euthyroid conditions, with limited data on subclinical statuses. Although RCTs have shown beneficial effects, stronger for testosterone and the GH-IGF-1 axis and less evident for thyroid hormones, in improving different hematological parameters, there is no clear evidence for the usefulness of hormonal treatment in improving anemia in older subjects. Thus, more clinical and research efforts are needed to investigate the hormonal contribution to anemia in the older individuals.

Growth hormone receptor signaling is dispensable for HSC function and aging

Growth hormone receptor (Ghr) signaling is important in a wide variety of cellular processes including aging; however, the role of Ghr signaling in hematopoietic stem cell (HSC) biology remains unexplored. Within the hematopoietic system, Ghr is expressed in a highly HSC-specific manner and is significantly upregulated during aging. Exposure of young and old HSCs to recombinant growth hormone ex vivo led to diminished short-term reconstitution and restored B-cell output from old HSCs. Hematopoietic-specific genetic deletion of Ghr neither impacted steady-state hematopoiesis nor serial transplantation potential. Repeat challenge with 5-fluorouracil showed that Ghr was dispensable for HSC activation and homeostatic recovery in vivo and, after challenge, Ghr-deficient HSCs functioned normally through serial transplantation. Although exogenous Gh induces age-dependent HSC effects, these results indicate that Ghr signaling appears largely dispensable for HSC function and aging.

hGH promotes megakaryocyte differentiation and exerts a complementary effect with c-Mpl ligands on thrombopoiesis

hGH has a distinct capacity to promote the differentiation, especially the terminal differentiation of human primary megakaryocytes. hGH exerts a complementary and synergistic effect with c-Mpl ligands on thrombopoiesis.

Serum insulin-like growth factor-1 (IGF-1) during CF pulmonary exacerbation: trends and biomarker correlations

INTRODUCTION

Cystic fibrosis (CF) is characterized by low circulating levels of insulin-like growth factor-1 (IGF-1), a hormone produced by the liver that governs anabolism and influences immune cell function. Because treatment of CF pulmonary exacerbation (CFPE) often improves body weight and lung function, we questioned whether serum IGF-1 trends were emblematic of these responses. Initially, we compared serum levels between healthy adults with CF and controls of similar age. We then measured serum IGF-1 throughout the CFPE cycle. We also investigated correlations among IGF-1 and other serum biomarkers during CFPE.

METHODS

Anthopometric, spirometric, and demographic data were collected. Serum IGF-1 concentrations were measured by ELISA.

RESULTS

CF subjects in their usual state of health had lower serum IGF-1 levels than controls. Serum IGF-1 concentrations fell significantly from baseline at the beginning of CFPE. Treatment with intravenous antibiotics was associated with significant improvement in serum IGF-1 levels, body mass index (BMI), and percent-predicted forced expiratory volume in 1 sec (FEV1 %). At early and late CFPE, serum IGF-1 was directly correlated with FEV1 %, serum iron, hemoglobin concentration, and transferrin saturation (TSAT) and indirectly correlated with alpha-1-antitrypsin.

CONCLUSIONS

This study not only supports the paradigm that CF is characterized by IGF-1 deficiency but also that trends in lung function, nutritional status, and serum IGF-1 are related. Improvements in all three parameters after antibiotics for CFPE likely highlight the connection between lung function and nutritional status in CF. Close correlations among IGF-1 and iron-related hematologic parameters suggest that IGF-1 may participate in CF iron homeostasis, another process that is known to be influenced by CFPE.

Effect of recombinant human growth hormone (rhGH) on hemoglobin concentration in children with idiopathic growth hormone deficiency-related anemia

Normocytic-normochromic anemia (NC/NC) has been attributed to impaired bone marrow erythropoiesis in growth hormone (GH)-deficient patients. Moreover, the GH/insulin-like growth factor-1 (IGF-1) axis has been implicated in erythropoiesis regulation. In this retrospective multicenter study, we evaluated the incidence of NC/NC anemia in 279 children (196 boys), median age 10.52 years, with isolated idiopathic GH deficiency, and the effect of recombinant human growth hormone (rhGH) therapy on hemoglobin levels. At 6-month intervals, we recorded the Hb standard deviation score (Hb-SDS), the IGF-1-SDS, weight, height, and pubertal stage. Forty-one boys and 7 girls had NC/NC anemia before starting substitutive therapy (-2.59 SD). The Hb-SDS was significantly increased (P<0.05) after 12 months of rhGH therapy. The effect of rhGH continued up to 48 months (-0.39 SD), at which point all children had normal hemoglobin values. In conclusion, rhGH therapy resulted in normal hemoglobin values in all children enrolled in the study. These data support the concept that the GH/IGF-1 axis promotes erythropoiesis in vivo.

Subcutaneous administration of rhIGF-I post irradiation exposure enhances hematopoietic recovery and survival in BALB/c mice

It is unclear how to effectively mitigate against irradiation injury. In this study, we studied the capacity of recombinant human insulin-like growth factor-I (rhIGF-I) on hematologic recovery in irradiated BALB/c mice and its possible mechanism. BALB/c mice were injected with rhIGF-I subcutaneously at a dose of 100 μg/kg twice daily for 7 days after total body irradiation. Compared with a saline control group, treatment with rhIGF-I significantly improved the survival of mice after lethal irradiation (7.5 Gy). It was found that treatment with rhIGF-I not only could increase the frequency of Sca-1(+) cells in bone marrow harvested at Day 14 after irradiation, but also it could decrease the apoptosis of mononuclear cells induced by irradiation as measured by flow cytometry, suggesting that rhIGF-I may mediate its effects primarily through promoting hematopoietic stem cell/progenitor survival and protecting mononuclear cells from apoptosis after irradiation exposure. Moreover, we have found that rhIGF-I might facilitate thrombopoiesis in an indirect way. Our data demonstrated that rhIGF-I could promote overall hematopoietic recovery after ionizing radiation and reduce the mortality when administered immediately post lethal irradiation exposure.

HIV disease progression despite suppression of viral replication is associated with exhaustion of lymphopoiesis

The mechanisms of CD4(+) T-cell count decline, the hallmark of HIV disease progression, and its relationship to elevated levels of immune activation are not fully understood. Massive depletion of CD4(+) T cells occurs during the course of HIV-1 infection, so that maintenance of adequate CD4(+) T-cell levels probably depends primarily on the capacity to renew depleted lymphocytes, that is, the lymphopoiesis. We performed here a comprehensive study of quantitative and qualitative attributes of CD34(+) hematopoietic progenitor cells directly from the blood of a large set of HIV-infected persons compared with uninfected donors, in particular the elderly. Our analyses underline a marked impairment of primary immune resources with the failure to maintain adequate lymphocyte counts. Systemic immune activation emerges as a major correlate of altered lymphopoiesis, which can be partially reversed with prolonged antiretroviral therapy. Importantly, HIV disease progression despite elite control of HIV replication or virologic success on antiretroviral treatment is associated with persistent damage to the lymphopoietic system or exhaustion of lymphopoiesis. These findings highlight the importance of primary hematopoietic resources in HIV pathogenesis and the response to antiretroviral treatments.

Advances in adoptive immunotherapy to accelerate T-cellular immune reconstitution after HLA-incompatible hematopoietic stem cell transplantation

Although partially HLA-mismatched hematopoietic stem cell transplantation (HSCT) has become an important therapeutic option for children with primary immunodeficiencies, delayed reconstitution of the T-cell compartment remains a major clinical concern. Adoptive immunotherapies to provide recipients with a protective and diverse T-cell repertoire in the months following HSCT are warranted. In order to improve T-cell reconstitution after T-cell-depleted HSCT, different strategies are currently being studied. Some are based on administration of modified mature T cells (e.g., allodepleted T cells or pathogen-specific T cells). Others aim at accelerating de novo thymopoiesis from donor-derived hematopoietic stem cells in vivo via the administration of thymopoietic agents or the transfer of large numbers of T-cell precursors generated ex vivo. The present article will provide a brief summary of recent advances in the field of allodepletion and adoptive transfer of pathogen-specific T cells and a detailed discussion of strategies for enhancing thymopoiesis in vivo.

Increased haematopoietic progenitor cells are associated with poor outcome in patients with metastatic renal cancer treated with sunitinib

BACKGROUND

Haematopoietic progenitor cells (HPCs) are present in blood in metastatic renal cell cancer (mRCC). We investigate their expression in mRCC patients treated with sunitinib and correlate their expression with plasma growth factor levels [insulin-like growth factor (IGF)-1].

METHODS

Circulating HPCs (CD34(+)/CD45(+)) and plasma IGF-1 levels were measured at specific sequential time points (0, 6, 18 and 28 weeks) in 43 untreated mRCC patients receiving sunitinib (50 mg for 28 days followed by 14-day off treatment). Univariate and multivariate analysis assessed the prognostic significance of HPCs and IGF-1.

RESULTS

HPCs levels were raised in 40 of 43 (93%) of patients. IGF-1 levels were raised in 9 of 43 patients (21%). Univariate and multivariate analysis revealed that high HPCs before treatment were associated with a significantly shorter overall survival (hazard ratio 3.3, 95% confidence interval 1.23-8.8, P=0.01), which was not the case for IGF-1 levels. Both HPC and IGF-1 levels fell with sunitinib (61% and 14% fall, respectively, P <0.05 for both). A positive correlation between the falls in HPC and IGF-1 occurred (P<0.001).

CONCLUSIONS

HPCs are over expressed in the peripheral blood in the majority of patients with mRCC. Higher levels are associated with poor prognosis. A concurrent fall in HPCs and growth factor expression (IGF-1) with sunitinib occurs.

Emerging strategies to boost thymic function

The thymus constitutes the primary lymphoid organ for the generation of T cells. Its function is particularly susceptible to various negative influences ranging from age-related involution to atrophy as a consequence of malnutrition, infection or harmful iatrogenic influences such as chemotherapy and radiation. The loss of regular thymus function significantly increases the risk for infections and cancer because of a restricted capacity for immune surveillance. In recent years, thymus-stimulatory, thymus-regenerative, and thymus-protective strategies have been developed to enhance and repair thymus function in the elderly and in individuals undergoing hematopoietic stem cell transplantation. These strategies include the use of sex steroid ablation, the administration of growth and differentiation factors, the inhibition of p53, and the transfer of T cell progenitors to alleviate the effects of thymus dysfunction and consequent T cell deficiency.

Insulin-like growth factor-I regulates the liver microenvironment in obese mice and promotes liver metastasis

Among the mechanisms implicated in the tumor-promoting effects of obesity, signaling by insulin-like growth factor-I (IGF-I) and insulin has received considerable attention. However, the emerging realization that obesity is associated with chronic inflammation has prompted other consideration of how the IGF-I axis may participate in cancer progression. In the present study, we used two mouse models of chronic (LID) and inducible (iLID) igf-1 gene deficiency in the liver to investigate the role of IGF-I in regulating the host microenvironment and colorectal carcinoma growth and metastasis in obese mice. Obese mice had a heightened inflammatory response in the liver, which was abolished in mice with chronic IGF-I deficiency (LID). In control animals changes to the hepatic microenvironment associated with obesity sustained the presence of tumor cells in the liver and increased the incidence of hepatic metastases after intrasplenic/portal inoculation of colon carcinoma cells. These changes did not occur in LID mice with chronic IGF-1 deficiency. In contrast, these changes occurred in iLID mice with acute IGF-1 deficiency, in the same manner as the control animals, revealing a fundamental difference in the nature of the requirement for IGF-1 on tumor growth and metastasis. In the setting of obesity, our findings imply that IGF-1 is critical to activate and sustain an inflammatory response in the liver that is needed for hepatic metastasis, not only through direct, paracrine effect on tumor cell growth, but also through indirect effects involving the tumor microenvironment.

Sizes of abdominal organs in adults with severe short stature due to severe, untreated, congenital GH deficiency caused by a homozygous mutation in the GHRH receptor gene

OBJECTIVE

To assess the sizes of intra-abdominal organs of adult subjects with untreated severe congenital isolated GH deficiency (IGHD) due to lack of functional GHRH receptor (GHRH-R), and to verify whether there is proportionality between size of organ and adult stature and body surface area (BSA).

SUBJECTS AND METHODS

By using ultrasound, we studied the sizes (absolute and corrected by height, weight and BSA) of the intra-abdominal organs of 18 adult subjects with IGHD (eight females, IGHD group) who have never received GH replacement therapy. They were all homozygous for the same null mutation (IVS1 + 1G --> A) in the GHRH receptor gene (GHRH-R). They were compared with normal controls from the same region.

RESULTS

After correction for BSA, subjects lacking a functional GHRH-R have normal prostate and ovaries size, small spleen and uterus, and large liver, pancreas and kidney.

CONCLUSIONS

Size of individual abdominal organs is influenced in different ways by severe and congenital lack of GH due to a GHRH-R mutation.

Low-dose growth hormone administration mobilizes endothelial progenitor cells in healthy adults

OBJECTIVE

Endothelial progenitor cells (EPCs) mobilize from the bone marrow secondary to a stimulus and home to sites of injury, where they differentiate into endothelial cells and contribute to the repair of damaged vasculature. We hypothesized that growth hormone (GH) administration would increase the number of circulating EPCs in adults and thereby represent a mechanism to enhance vascular health.

DESIGN

A prospective trial of low-dose GH (0.03mg/kg/week for 4 weeks followed by 0.06mg/kg/week for a maximum of four additional weeks) in 10 healthy adults (6 males and 4 females; mean age 37 years, range 26-65). Primary outcomes measured included the number of circulating EPCs as assessed by colony-forming unit (CFU) assay and flow cytometry. Secondary outcomes included plasma measurements of known mediators of EPC mobilization and indices of nitric oxide (NO). Outcomes were measured at baseline and at study completion.

RESULTS

GH administration increased serum IGF-1 (143ng/mL [IQR 121-164] to 222 [IQR 194-244]; P=0.005). The increase in early-outgrowth EPCs (13 CFU per high-power field [IQR 6-24] to 19 [IQR 13-40]; P=0.005) correlated with the peak IGF-1 after adjustment for the baseline number of early-outgrowth EPCs (r=0.719 [95% CI 0.06, 0.93]; P=0.027). The number of late-outgrowth EPCs as well as CD34+, VEGFR2(KDR)+, and AC133+ cells did not significantly change. Other mediators of EPC mobilization were stable while plasma nitrite trended upwards (1.3micromol/L [IQR 0-2.5] to 3.7 [IQR 2.2-8.9]; P=0.052).

CONCLUSIONS

GH administration selectively augments the early-outgrowth EPC population in healthy individuals. These findings both support GH replacement in the setting of GH deficiency to maintain vascular integrity and have implications for the use of GH in future regenerative cell-based therapies. Furthermore, the decrease in EPCs observed with aging may in part be explained by the declining somatotropic axis, and thereby contribute to cardiovascular senescence.

Low insulin-like growth factor I and leukopenia in anorexia nervosa

OBJECTIVE

Considering that leukopenia and anemia are commonly observed in anorexia nervosa (AN) and that growth hormone (GH) and insulin-like growth factor-I (IGF-I) markedly influence the activation, growth and survival of hemopoietic cells, we sought for possible relationships between hematologic parameters and the GH-IGF-I axis in a group of patients with AN.

METHOD

Twenty patients were studied. Leukocyte and erythrocyte counts, as well as baseline serum GH levels and IGF-I standard deviation score (SDS) values, were determined in each participant and correlations between parameters were searched.

RESULTS

Leukocyte and erythrocyte counts, as well as IGF-I SDS values, were significantly lower, conversely GH was significantly higher in AN patients than in normal weight participants. In patients, IGF-I SDS values were positively correlated with leukocyte count and BMI, whereas no correlation was found between IGF-I SDS and hemoglobin or erythrocytes.

CONCLUSION

The demonstration of a positive correlation between leukocyte number and circulating IGF-I in AN suggests a likely pathogenetic role of IGF-I deficiency in this hematologic abnormality.

Growth hormone enhances thymic function in HIV-1-infected adults

Growth hormone (GH) is an underappreciated but important regulator of T cell development that can reverse age-related declines in thymopoiesis in rodents. Here, we report findings of a prospective randomized study examining the effects of GH on the immune system of HIV-1-infected adults. GH treatment was associated with increased thymic mass. In addition, GH treatment enhanced thymic output, as measured by both the frequency of T cell receptor rearrangement excision circles in circulating T cells and the numbers of circulating naive and total CD4(+) T cells. These findings provide compelling evidence that GH induces de novo T cell production and may, accordingly, facilitate CD4(+) T cell recovery in HIV-1-infected adults. Further, these randomized, prospective data have shown that thymic involution can be pharmacologically reversed in humans, suggesting that immune-based therapies could be used to enhance thymopoiesis in immunodeficient individuals.

Immunosenescence of ageing

Ageing is a complex process that negatively impacts the development of the immune system and its ability to function. The mechanisms that underlie these age-related defects are broad and range from defects in the haematopoietic bone marrow to defects in peripheral lymphocyte migration, maturation and function. The thymus is a central lymphoid organ responsible for production of naïve T cells, which play a vital role in mediating both cellular and humoral immunity. Chronic involution of the thymus gland is thought to be one of the major contributing factors to loss of immune function with increasing age. It has recently been demonstrated that thymic atrophy is mediated by a shift from a stimulatory to a suppressive cytokine microenvironment. In this review we present an overview of the morphological, cellular and biochemical changes that have been implicated in the decline of thymic and peripheral immune function with ageing. We conclude with the clinical implications of age-associated immunosenescence to vaccine development for tumours and infectious disease. A fundamental understanding of the complex mechanisms by which ageing attenuates immune function will enable translational research teams to develop new therapies and vaccines specifically aimed at overcoming these defects in immunological function in the aged.

TLR agonists induce the differentiation of human bone marrow CD34+ progenitors into CD11c+ CD80/86+ DC capable of inducing a Th1-type response

We recently reported that human bone marrow hematopoietic CD34(+) progenitors express functional Toll-like receptors (TLR) and can differentiate into myeloid cells just by stimulation with resiquimod (R848), a specific agonist for TLR7/8. However, the mechanisms by which R848 induces cell differentiation, the effects of other TLR agonists and the functionality of the differentiated cells are not known. Comparable to R848, loxoribine (a TLR7 agonist) and Pam(3)CSK(4) (a TLR2 agonist) induced cytokine production and cell differentiation along the myeloid lineage. R848 and loxoribine were more effective than Pam(3)CSK(4) at inducing the lineage-negative (CD11c(+) CD14(-)) dendritic cells (DC), whereas Pam(3)CSK(4) was more effective at inducing CD11c(+) CD14(+) monocytes. Both cell subsets expressed CD80/CD86 and HLA-DR molecules; however, they showed differential expression of CD1a, CD1b, CD1c, CD11b, CD206 and CD207 markers when compared with each other. Cell differentiation into DC was significantly inhibited by an anti-TNF-alpha nonoclonal antibody. The CD11c(+) CD14(-) subset was isolated and shown to be more potent in stimulating an alloreaction than the CD11c(+) CD14(+) subset. Collectively, these data highlight the differential effects of TLR agonists on human bone marow CD34(+) progenitor cells and provide a new opportunity for generating functional DC that would be useful in cancer vaccination.

Insulin-like growth factor-binding protein 3 and hemoglobin concentration in older persons living in the community

A decreased hemoglobin concentration is a common clinical condition in elderly subjects, and in at least 20% of the cases it is not possible to directly attribute the anemia to specific factors. The aim of the present study was to evaluate the relationship of different levels of insulin-like growth factor-binding protein 3 (IGFBP-3) with the blood concentration of hemoglobin in persons aged 80 years and older. Data are from a baseline evaluation of the Aging and Longevity in the Sirente Geographic Area (ilSIRENTE) study (n=253). Analysis of covariance was used to examine the effect of different IGFBP-3 levels on hemoglobin concentration. After adjustment for potential confounding variables, which included age, sex, number of diseases, renal failure, cancer, gastric ulcer, albumin, and iron concentrations, individuals in the group with higher IGFBP-3 concentrations showed a significantly higher mean hemoglobin concentration than participants in the group with lower IGFBP-3 concentrations (13.4 +/- 1.4 g/dL versus 12.9 +/- 1.9 g/dL, respectively; P=.03). In conclusion, the present study has shown that a higher IGFBP-3 level is associated with a higher hemoglobin concentration among older people living in the community. This finding suggests that the growth hormone/IGF axis may play an important role in hematopoiesis, and it may be implicated in the age-related decline in hemoglobin concentration.

Signaling through Toll-like Receptor 7/8 Induces the Differentiation of Human Bone Marrow CD34+ Progenitor Cells along the Myeloid Lineage

Toll-like receptors (TLRs) play a key role in pathogen recognition and regulation of the innate and adaptive immune responses. Although TLR expression and signaling have been investigated in blood cells, it is currently unknown whether their bone marrow ancestors express TLRs and respond to their ligands. Here we found that TLRs (e.g. TLR4, TLR7 and TLR8) were expressed by freshly isolated human bone marrow (BM) hematopoietic CD34+ progenitor cells. Incubation of these primitive cells with TLR ligands such as immunostimulatory small interfering RNAs and R848, a specific ligand for TLR7/8, induced cytokine production (e.g. IL1-beta, IL6, IL8, TNF-alpha, GM-CSF). Moreover, TLR7/8 signaling induced the differentiation of BM CD34+ progenitors into cells with the morphology of macrophages and monocytic dendritic precursors characterized by the expression of CD13, CD14 and/or CD11c markers. By contrast, R848 ligand did not induce the expression of glycophorin A, an early marker for erythropoiesis. Collectively, the data indicate for the first time that human BM CD34+ progenitor cells constitutively express functional TLR7/TLR8, whose ligation can induce leukopoiesis without the addition of any exogenous cytokines. Thus, TLR signaling may regulate BM cell development in humans.

Antiretroviral agents during pregnancy: consequences on hematologic parameters in HIV-exposed, uninfected newborn infant

OBJECTIVES

To study the effect of antiretroviral drugs administered to pregnant women on hematologic parameters of the neonate.

STUDY DESIGN

A prospective cohort study was conducted on 52 neonates divided into three groups: ZDV group, infants born to HIV-infected mothers taking zidovudine (n=18); triple therapy (TT) group, infants born to mothers taking zidovudine+lamivudine+nelfinavir (n=22), and control group, infants born to normal women (n=12). Umbilical cord blood from the newborn infant was used to determine hemoglobin, lymphocyte and platelet. Data were analyzed statistically by the nonparametric tests, with the level of significance set at p<0.05.

RESULTS

The major maternal demographic and anthropometric data were homogeneous for the various groups. There was a reduction in hemoglobin levels at birth among TT group newborns (p=0.016). There was no difference between groups regarding gestation length, Apgar scores, platelets or absolute lymphocyte count for the newborn.

CONCLUSIONS

An association between the use of combination antiretroviral therapy during pregnancy and reduced neonatal hemoglobin levels was observed, supporting the need for short- and long-term follow-up of infants exposed to antiretroviral drugs during uterine life.