Insulin-like growth factor I--an important intrauterine growth factor

Delayed First Feeding Chronically Impairs Larval Fish Growth Performance, Hepatic Lipid Metabolism, and Visceral Lipid Deposition at the Mouth-Opening Stage

During the mouth-opening stage, fish larvae are susceptible to delayed first feeding (DFF). In this study, we explored the effects of DFF for two days on later growth and energy metabolism in larval fish. Results showed that DFF chronically impaired larval growth performance, thereby reducing the efficiency of feed utilization by larvae. In DFF larvae, the mRNA levels of growth inhibitors (i.e., igfbp1a and igfbp1b) were significantly upregulated and consistently maintained at high expression levels, which may be an important attribution of larval growth retardation. Concomitantly, DFF retarded the growth of adipose tissue and reduced lipid deposition in larval viscera, suggesting lipid metabolism is disordered in DFF larvae and generates inefficient lipid reserves. In the liver, we observed that DFF resulted in a significant accumulation of neutral lipids, and this phenotype did not disappear rapidly after DFF larvae received exogenous nutrition. As to the transcript analyses, we found that the expression of genes related to hepatic lipid synthesis (e.g., srebf1, srebf2, dgat1a, dgat1b, fasn, and scdb) in DFF larvae was consistently upregulated, while the expression of genes involved in lipid transport (e.g., apoa2, apoa4b.1, and apoa4b.3) was downregulated. Therefore, it appears that the inefficient lipid reserves in DFF larvae are associated with their hepatic lipid transport dysfunction. Taken together, our findings contribute to understanding the impairments to fish larvae caused by delayed first feeding during the mouth-opening stage and to aiding larval management in the aquaculture industry.

Identification of Potential ceRNA Network and Patterns of Immune Cell Infiltration in Systemic Sclerosis-Associated Interstitial Lung Disease

Purpose

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is one of the most severe complications of systemic sclerosis (SSc) and is the leading cause of SSc-related deaths. However, the precise pathogenesis of pulmonary fibrosis in SSc-ILD remains unknown. This study aimed to evaluate the competing endogenous RNA (ceRNA) regulatory network and immune cell infiltration patterns in SSc-ILD.

Methods

One microRNA (miRNA) and three messenger RNA (mRNA) microarray datasets were obtained from the Gene Expression Omnibus (GEO) database. Then, the differentially expressed miRNAs (DEmiRs) and mRNAs (DEMs) between SSc-ILD patients and normal controls were identified, respectively, followed by the prediction of the target genes and target lncRNAs of DEmiRs. The overlapping genes between DEmiRs target genes and DEMs were identified as core mRNAs to construct the ceRNA network. In addition, the “Cell Type Identification by Estimating Relative Subsets of Known RNA Transcripts (CIBERSORT)” algorithm was used to analyze the composition of infiltrating immune cells in lung tissues of SSc-ILD patients and controls, and differentially expressed immune cells were recognized. The correlation between immune cells and core mRNAs was evaluated by Pearson correlation analysis.

Results

Totally, 42 SSc-ILD lung tissues and 18 normal lung tissues were included in this study. We identified 35 DEmiRs and 142 DEMs and predicted 1,265 target genes of DEmiRs. Then, 9 core mRNAs related to SSc-ILD were recognized, which were the overlapping genes between DEmiRs target genes and DEMs. Meanwhile, 9 DEmiRs related to core mRNAs were identified reversely, and their target lncRNAs were predicted. In total, 9 DEmiRs, 9 core mRNAs, and 51 predicted lncRNAs were integrated to construct the ceRNA regulatory network of SSc-ILD. In addition, 9 types of immune cells were differentially expressed in lung tissues between SSc-ILD patients and controls. Some core mRNAs, such as COL1A1, FOS, and EDN1, were positively or negatively correlated with the number of infiltrating immune cells.

Conclusion

This is the first comprehensive study to construct the potential ceRNA regulatory network and analyze the composition of infiltrating immune cells in lung tissues of SSc-ILD patients, which improves our understanding of the pathogenesis of SSc-ILD.

Insights from the clinical phenotype of subjects with Laron syndrome in Ecuador

The Ecuadorian cohort of subjects with LS has taught us valuable lessons since the late 80's. We have learned about migration of Sephardic Jews to our country, their isolation in remote hamlets and further inbreeding. These geographical, historical and social determinants induced dissemination of a growth hormone (GH) receptor mutation which widely occurred in those almost inaccessible villages. Consequently, the world's largest Laron syndrome (LS) cohort emerged in Loja and El Oro, two of the southern provinces of Ecuador. We have been fortunate to study these patients since 1987. New clinical features derived from GH insensitivity, their growth patterns as well as treatment with exogenous insulin-like growth factor I (IGF-I) have been reported. Novel biochemical characteristics in the field of GH insensitivity, IGFs, IGF binding proteins (BP) and their clinical correlates have also been described. In the last few years, studies on the morbidity and mortality of Ecuadorian LS adults surprisingly demonstrated that despite obesity, they had lower incidence of diabetes and cancer than their relatives. These events were linked to their metabolic phenotype of elevated but ineffective GH concentrations and low circulating IGF-I and IGFBP-3. It was also noted that absent GH counter-regulation induces a decrease in insulin resistance (IR), which results in low but highly efficient insulin levels which properly handle metabolic substrates. We propose that the combination of low IGF-I signaling, decreased IR, and efficient serum insulin concentrations are reasonable explanations for the diminished incidence of diabetes and cancer in these subjects.

IGF-I deficiency and enhanced insulin sensitivity due to a mutated growth hormone receptor gene in humans

Human size is achieved by the coordinated expression of many genes. From conception to adulthood, a given genomic endowment is modified by highly variable environmental circumstances. During each stage of a person's life, distinct nutritional and hormonal influences continuously shape growing physical features until mature characteristics are attained. Underlying processes depend on precise provision of substrates and energy extracted by insulin action from nutrients, which allows cell proliferation, differentiation, and survival, under the concerted actions of growth hormone and insulin-like growth factor-I (IGF-I). It should be noted that growth and metabolic signaling pathways are interdependent and superimposed at multiple levels. Attainment of a fully developed human phenotype should be considered as a harmonious increment in body size rather than a simple increase in height. From this perspective we herein analyze adult features of individuals with an inactive growth hormone receptor, who consequently have severely diminished concentrations of serum insulin and endocrine IGF-I.

Growth hormone receptor deficiency in humans associates to obesity, increased body fat percentage, a healthy brain and a coordinated insulin sensitivity

BACKGROUND

We have shown that subjects with Laron syndrome (LS) due to growth hormone receptor deficiency (GHRD) and their relatives have comparable brain structure and function; moreover, the brain of individuals affected with GHRD appears like those of younger people. While the functionally absent growth hormone receptor and the diminished concentrations of the insulin-like growth factor-I have been associated to these findings, the role of the insulin-glucose axis is emerging as an unavoidable consideration when determining the aetiology of these observations. In consequence, we decided to search for the potential and discrete associations between the neurological findings and several parameters of carbohydrate metabolism that might exist in the subjects affected with GHRD.

SUBJECTS AND METHODS

Individuals affected with GHRD were compared to relative controls. Besides standard measures of anthropometry, body composition and brain characteristics, the elements of the carbohydrate metabolism (CHO), including glucose, insulin, triacylglycerol and the free insulin growth factor binding protein 1 (IGFBP1) concentrations were determined. In addition, the correlations existing between the parameters of CHO and brain characteristics were established.

RESULTS

Besides the phenotypical characteristics of GHRD subjects, including those of brain structure and function, enhanced insulin sensitivity, and other minor, we observed that the insulin-regulated IGFBP1 had a consistent negative correlation with the main elements of the carbohydrate metabolism only in the individuals affected with the disease, and not in their relatives.

CONCLUSIONS

When compared to their relatives, subjects with GHRD who lack the counter-regulatory effects of GH on the insulin axis, despite their increased risk factor profile due to obesity and increased body fat percentage, have a healthy and younger looking brain associated to an enhanced and coordinated insulin sensitivity. Furthermore, it was observed that in the GHRD subjects IGFBP1 negatively correlates, in a constant and systematic manner, with the main elements of the CHO metabolism. These observations suggest a direct relationship between an efficient insulin sensitivity and a healthy brain.

Increased placental IGF-1/mTOR activity in macrosomia born to women with gestational diabetes

AIMS

Newborns of women with gestational diabetes mellitus (GDM) are susceptible to be macrosomic, even if the blood glucose levels are in normal ranges. The underlying mechanisms are largely unknown. We tested the hypothesis that placental insulin like growth factor(IGF)-I and mammalian target of rapamycin (mTOR) signaling is activated and amino acid transporter expression is increased in women with GDM who give birth to macrosomic babies.

METHODS

50 Chinese pregnant women with GDM whose blood glucose levels were controlled within normal range were recruited and their placental tissues were collected. 23 women gave birth to macrosomia and 27 women gave birth to babies with normal birth weight. We determined the phosphorylation of key signaling molecules (including Akt, IRS-1, S6K1, 4E-BP-1, and AMPKα) in the placental IGF-I and mTOR signaling pathways. We also measured the protein expression of the amino acid transporter systems A in placenta.

RESULTS

Birth weights (range 2500-4400 g) were positively correlated to maternal IGF-1 (P < 0.05). The activity of placental IGF-I and mTOR signaling was positively correlated (P < 0.05), whereas AMPKα phosphorylation was inversely (P < 0.05) correlated to birth weight. Protein expression of the system A isoform sodium-dependent neutral amino acid transporter (SNAT) 1 were positively correlated to birth weight (P < 0.05).

CONCLUSIONS

Up-regulation of placental amino acid transporters may contribute to more macrosomic babies in women with GDM. Activation of IGF-I and mTOR signaling pathways might involve in this effect.

Insulin resistance depends on GH counter-regulation in two syndromes of short stature

Specific phenotypic features of subjects affected with genetic syndromes depend on peculiarities of expression of each discrete mutation and on extent of its divergence from normal physiology. In this context, and when studying the GH/IGF-I axis of subjects with two different syndromes that include severe short stature (SSS), we noticed different metabolic phenotypes in each cohort. Subjects with Laron syndrome (LS), who have GH insensitivity (GHI), display obesity, increased body fat, enhanced insulin sensitivity and diminished incidence of diabetes mellitus. Subjects with a new syndrome (NS), who have normal GH signaling, display intrauterine growth retardation (IUGR), normal to slightly elevated body fat content, insulin resistance and early onset type 2 diabetes mellitus (T2DM). In consequence, we were able to observe the clinical consequences of different GH counter-regulation status on carbohydrate metabolism, especially considering that subjects with either syndrome most likely have diminished pancreatic reserve.

Stress-altered synaptic plasticity and DAMP signaling in the hippocampus-PFC axis; elucidating the significance of IGF-1/IGF-1R/CaMKIIα expression in neural changes associated with a prolonged exposure therapy

Traumatic stress patients showed significant improvement in behavior after a prolonged exposure to an unrelated stimulus. This treatment method attempts to promote extinction of the fear memory associated with the initial traumatic experience. However, the subsequent prolonged exposure to such stimulus creates an additional layer of neural stress. Although the mechanism remains unclear, prolonged exposure therapy (PET) likely involves changes in synaptic plasticity, neurotransmitter function and inflammation; especially in parts of the brain concerned with the formation and retrieval of fear memory (Hippocampus and Prefrontal Cortex: PFC). Since certain synaptic proteins are also involved in danger-associated molecular pattern signaling (DAMP), we identified the significance of IGF-1/IGF-1R/CaMKIIα expression as a potential link between the concurrent progression of synaptic and inflammatory changes in stress. Thus, a comparison between IGF-1/IGF-1R/CaMKIIα, synaptic and DAMP proteins in stress and PET may highlight the significance of PET on synaptic morphology and neuronal inflammatory response. In behaviorally characterized Sprague-Dawley rats, there was a significant decline in neural IGF-1 (p<0.001), hippocampal (p<0.001) and cortical (p<0.05) IGF-1R expression. These animals showed a significant loss of presynaptic markers (synaptophysin; p<0.001), and changes in neurotransmitters (VGLUT2, Tyrosine hydroxylase, GABA, ChAT). Furthermore, naïve stressed rats recorded a significant decrease in post-synaptic marker (PSD-95; p<0.01) and synaptic regulator (CaMKIIα; p<0.001). As part of the synaptic response to a decrease in brain CaMKIIα, small ion conductance channel (KCa2.2) was upregulated in the brain of naïve stressed rats (p<0.01). After a PET, an increase in IGF-1 (p<0.05) and IGF-1R was recorded in the Stress-PET group (p<0.001). As such, hippocampal (p<0.001), but not cortical (ns) synaptophysin expression increased in Stress-PET. Although PSD-95 was relatively unchanged in the hippocampus and PFC, CaMKIIα (p<0.001) and KCa2.2 (p<0.01) were upregulated in Stress-PET, and may be involved in extinction of fear memory-related synaptic potentials. These changes were also associated with a normalized neurotransmitter function, and a significant reduction in open space avoidance; when the animals were assessed in elevated plus maze (EPM). In addition to a decrease in IGF-1/IGF-1R, an increase in activated hippocampal and cortical microglia was seen in stress (p<0.05) and after a PET (Stress-PET; p<0.001). Furthermore, this was linked with a significant increase in HMGB1 (Hippocampus: p<0.001, PFC: p<0.05) and TLR4 expression (Hippocampus: p<0.01; PFC: ns) in the neurons. Taken together, this study showed that traumatic stress and subsequent PET involves an event-dependent alteration of IGF1/IGF-1R/CaMKIIα. Firstly, we showed a direct relationship between IGF-1/IGF-1R expression, presynaptic function (synaptophysin) and neurotransmitter activity in stress and PET. Secondly, we identified the possible role of CaMKIIα in post-synaptic function and regulation of small ion conductance channels. Lastly, we highlighted some of the possible links between IGF1/IGF-1R/CaMKIIα, the expression of DAMP proteins, Microglia activation, and its implication on synaptic plasticity during stress and PET.

Intrauterine and postnatal growth failure with normal GH/IGF1 axis and insulin-resistant diabetes in a consanguineous kinship

OBJECTIVE

To describe the clinical and biochemical features, and perform molecular analysis for candidate abnormalities in a novel familial syndrome of intrauterine growth retardation (IUGR), failure of an adolescent growth spurt with proportional adult short stature, minimal subluxation of the 5th metacarpal-phalangeal joint, and adult-onset insulin-resistant diabetes unrelated to obesity or other manifestations of metabolic syndrome (MS).

DESIGN

Detailed clinical history, auxological, biochemical, radiological, and molecular studies, including DNA analysis and in vitro study of the GH/IGF1 pathway.

MATERIALS AND METHODS

Ten affected adults from two generations of five related families were studied in detail, and information obtained about nine other likely affected individuals.

RESULTS

Height Z-scores ranged from -7.3 to -3.8. Unaffected parents of the older generation and frequency of confirmed and suspected instances of the syndrome in the two generations studied is consistent with autosomal recessive inheritance. Insulin resistance was uniformly present in seven subjects tested who were not taking insulin. Diabetes severity did not correlate with overweight. Subjects did not have other typical manifestations of MS such as substantial hyperlipidemia, osteoporosis, or hypertension. No biochemical abnormality in the GH/IGF1 axis or molecular defect was found.

CONCLUSIONS

While the association of IUGR and adult MS, including diabetes, has been well documented, these subjects did not have typical manifestations of MS. Abnormalities in common components that could result in a combination of IUGR, severe postnatal growth, and insulin resistance have been ruled out. A mutation in an unidentified gene may affect intrauterine and postnatal growth, with insulin resistance directly affected or as a result of this growth phenomenon.

Effect of insulin-like growth factor-I on Leishmania amazonensis promastigote arginase activation and reciprocal inhibition of NOS2 pathway in macrophage in vitro

We showed previously that insulin-like growth factor (IGF)-I induces an exacerbation of the lesion development in experimental cutaneous leishmaniasis favouring parasite growth within host macrophages. Here we studied the effect of IGF-I in vitro in BALB/c mouse peritoneal macrophages infected with stationary phase Leishmania amazonensis promastigotes. IGF-I was used to pre-incubate either macrophage or parasite before infection of the macrophages or adding it at the start of the Leishmania-macrophage culture and maintaining it throughout the experimental period. Independent of stimulation protocol, IGF-I induced significantly increased parasite growth within macrophages. Arginase activation considered as a key factor in Leishmania growth was studied, and its expression and activity were increased in Leishmania-infected macrophages but significantly more in infected cells upon IGF-I stimulus, an effect specifically inhibited by NOHA. Arginase known to be present on Leishmania was also studied, and its expression and activity were seen in the absence of any stimulus but significantly increased after 5 min of incubation with IGF-I. In addition, Leishmania was pre-incubated with NOHA for 5 min, washed, then macrophages infected observing a significantly reduced parasite burden in both IGF-I-stimulated and non-stimulated macrophages. Reciprocal decrease in the nitric oxide (NO) level and inhibition of nitric oxide synthase (NOS2) expression were also observed in IGF-I-stimulated infected macrophages. Our data strongly suggest that IGF-I induces preferential expression and activation of Leishmania promastigote arginase, contributes to the alternative activation of macrophages in the context of innate immunity and interferes with NOS pathway in infected macrophages probably as a reciprocal effect.

Insulin-like growth factor (IGF)-I and insulin in normal and growth-restricted mother/infant pairs

Insulin-like growth factor (IGF)-I and insulin are essential for fetal growth. We investigated perinatal changes of both factors in 40 mothers and their 20 appropriate-for-gestational-age (AGA) and 20 intrauterine-growth-restricted (IUGR) fetuses and neonates on day 1 (N1) and day 4 (N4) postpartum. Fetal and N1, but not N4, IGF-I levels were increased in AGA (P < .001 and P = .037, resp.). N1 insulin levels were lower in IUGR (P = .048). Maternal, fetal, and N1 IGF-I, and fetal insulin levels positively correlated with customized centiles (r = .374, P = .035, r = .608, P < .001, r = .485, P = .006, and r = .654, P = .021, resp.). Female infants presented elevated fetal and N4 IGF-I levels (P = .023 and P = .016, resp.). Positive correlations of maternal, fetal, and neonatal IGF-I levels, and fetal insulin levels with customized centiles underline implication of both hormones in fetal growth. IUGR infants present gradually increasing IGF-I levels. Higher IGF-I levels are documented in females.

Controversy in clinical endocrinology: reclassification of insulin-like growth factor I production and action disorders

CONTEXT

The need for the least ambiguous terminology for disorders affecting IGF-I production and action has become necessary with identification of defects at various steps in the GH-IGF-I axis and the promotion of new indications for and modalities of growth therapy. No generally agreed-upon or consensus-derived classification exists.

OBJECTIVE

Our objective was to designate all disorders affecting IGF-I production and action by their discrete location, as is already done with the defects in pituitary differentiation factors, avoiding imprecise and ambiguous terminology.

CONCLUSIONS

We propose a pragmatic classification that is a precise listing of specific disorders sequentially following the GH-IGF-I axis, using their accepted designations, and the abolition of nonspecific or ambiguous terminology. This concept permits ready insertion of new discoveries.

Genetic, physiologic and ecogeographic factors contributing to variation in Homo sapiens: Homo floresiensis reconsidered

A new species, Homo floresiensis, was recently named for Pleistocene hominid remains on Flores, Indonesia. Significant controversy has arisen regarding this species. To address controversial issues and refocus investigations, I examine the affinities of these remains with Homo sapiens. Clarification of problematic issues is sought through an integration of genetic and physiological data on brain ontogeny and evolution. Clarification of the taxonomic value of various 'primitive' traits is possible given these data. Based on this evidence and using a H. sapiens morphological template, models are developed to account for the combination of features displayed in the Flores fossils. Given this overview, I find substantial support for the hypothesis that the remains represent a variant of H. sapiens possessing a combined growth hormone-insulin-like growth factor I axis modification and mutation of the MCPH gene family. Further work will be required to determine the extent to which this variant characterized the population.

Insulin-like growth factor-I promotes proliferation and migration of cavernous smooth muscle cells

To better understand the physiology of cavernous smooth muscle cells (CSMC), particularly their regulation by IGF-I, we isolated CSMC from rats of various ages and grew them as cell cultures. CSMC from very young (1 week of age) and very old (28 months of age) rats secreted the least amounts of IGF-I, and those from 16-week-old rats the most. IGF-I stimulated growth of CSMC at an optimal concentration of 12.5 ng/ml. At this concentration, CSMC from 11-week-old rats showed the highest growth rate and CSMC from 28-month-old rats showed the lowest. The optimal IGF-I concentration for migration of CSMC was 10 ng/ml. At this concentration, CSMC from 4-week-old rats showed the highest migratory rate and CSMC from 28-month-old rats showed the lowest. IGF-I also stimulated VEGF secretion from CSMC at an optimal concentration of 10 ng/ml. At this concentration, CSMC from 16-week-old rats secreted VEGF the most and CSMC from 28-month-old rats secreted the least. The expression levels of IGF-IR paralleled the IGF-I-regulated growth rates of these cells. Expression of IGF-IR was identified in the cavernous smooth muscle and the urethra epithelium of the penis.

Associations of IGF-I, IGFBP-1 and IGFBP-3 on intrauterine growth and early catch-up growth

Fetal cord blood IGF-I, IGFBP-1 and IGFBP- 3 levels of appropriate-for-gestational-age (AGA) and intrauterine growth retardation (IUGR) babies are studied and followed up for 6-9 months, reevaluated for anthropometric measures and the effects of IGF-I, IGFBP-1 and IGFBP-3 on fetal growth and early catch-up growth is investigated. 23 AGA and 21 IUGR babies, totally 44 newborns, were included in the study protocol. IGF-I and IGFBP-3 levels were found to be high in AGAs with respect to IUGR babies and IGFBP-1 is found to be high in IUGR with respect to AGAs. IGF-I was significantly lower in IUGR babies without catch-up growth (group 2b) with respect to AGAs (group 1) and neonates with IUGR and catch-up growth (group 2a) and group 2a infants had higher IGF-I values than group 2b infants (p < 0.05). IGFBP-3 levels in group 1 were significantly higher than in the other two groups (p < 0.05), but not significantly different in group 2a with respect to group 2b (p > 0. 05). IGFBP-1 values showed no statistically significant difference with respect to the three different groups (p > 0.05). A good correlation was found between birth weight, postnatal weight and postnatal height and IGF-I and IGFBP-3 levels (p < 0.05) but not with IGFBP-1 levels. Aside from the height of the 3 groups of infants which were similar to each other after the follow-up period, IGF-I was significantly high in IUGR infants with catch-up growth with respect to IUGR infants without catch-up growth, indicating its importance in early catch-up growth of IUGR babies.

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.