Insulin-like Growth Factor I and its binding protein 3 in sepsis

Signals for Muscular Protein Turnover and Insulin Resistance in Critically Ill Patients: A Narrative Review

Sarcopenia in critically ill patients is a highly prevalent comorbidity. It is associated with a higher mortality rate, length of mechanical ventilation, and probability of being sent to a nursing home after the Intensive Care Unit (ICU). Despite the number of calories and proteins delivered, there is a complex network of signals of hormones and cytokines that affect muscle metabolism and its protein synthesis and breakdown in critically ill and chronic patients. To date, it is known that a higher number of proteins decreases mortality, but the exact amount needs to be clarified. This complex network of signals affects protein synthesis and breakdown. Some hormones regulate metabolism, such as insulin, insulin growth factor glucocorticoids, and growth hormone, whose secretion is affected by feeding states and inflammation. In addition, cytokines are involved, such as TNF-alpha and HIF-1. These hormones and cytokines have common pathways that activate muscle breakdown effectors, such as the ubiquitin-proteasome system, calpain, and caspase-3. These effectors are responsible for protein breakdown in muscles. Many trials have been conducted with hormones with different results but not with nutritional outcomes. This review examines the effect of hormones and cytokines on muscles. Knowing all the signals and pathways that affect protein synthesis and breakdown can be considered for future therapeutics.

IGF-1 and IGFBP-3 in Inflammatory Cachexia

Inflammation induces a wide response of the neuroendocrine system, which leads to modifications in all the endocrine axes. The hypothalamic–growth hormone (GH)–insulin-like growth factor-1 (IGF-1) axis is deeply affected by inflammation, its response being characterized by GH resistance and a decrease in circulating levels of IGF-1. The endocrine and metabolic responses to inflammation allow the organism to survive. However, in chronic inflammatory conditions, the inhibition of the hypothalamic–GH–IGF-1 axis contributes to the catabolic process, with skeletal muscle atrophy and cachexia. Here, we review the changes in pituitary GH secretion, IGF-1, and IGF-1 binding protein-3 (IGFBP-3), as well as the mechanism that mediated those responses. The contribution of GH and IGF-1 to muscle wasting during inflammation has also been analyzed.

Sepsis as a Pan-Endocrine Illness-Endocrine Disorders in Septic Patients

Sepsis is defined as "life-threatening organ dysfunction caused by a dysregulated host response to infection". One of the elements of dysregulated host response is an endocrine system disorder. Changes in its functioning in the course of sepsis affect almost all hormonal axes. In sepsis, a function disturbance of the hypothalamic-pituitary-adrenal axis has been described, in the range of which the most important seems to be hypercortisolemia in the acute phase. Imbalance in the hypothalamic-pituitary-thyroid axis is also described. The most typical manifestation is a triiodothyronine concentration decrease and reverse triiodothyronine concentration increase. In the somatotropic axis, a change in the secretion pattern of growth hormone and peripheral resistance to this hormone has been described. In the hypothalamic-pituitary-gonadal axis, the reduction in testosterone concentration in men and the stress-induced "hypothalamic amenorrhea" in women have been described. Catecholamine and β-adrenergic stimulation disorders have also been reported. Disorders in the endocrine system are part of the "dysregulated host response to infection". They may also affect other components of this dysregulated response, such as metabolism. Hormonal changes occurring in the course of sepsis require further research, not only in order to explore their potential significance in therapy, but also due to their promising prognostic value.

The Role of Hormones and Trophic Factors as Components of Preservation Solutions in Protection of Renal Function before Transplantation: A Review of the Literature

Transplantation is currently a routine method for treating end-stage organ failure. In recent years, there has been some progress in the development of an optimal composition of organ preservation solutions, improving the vital functions of the organ and allowing to extend its storage period until implantation into the recipient. Optimizations are mostly based on commercial solutions, routinely used to store grafts intended for transplantation. The paper reviews hormones with a potential nephroprotective effect, which were used to modify the composition of renal perfusion and preservation solutions. Their effectiveness as ingredients of preservation solutions was analysed based on a literature review. Hormones and trophic factors are innovative preservation solution supplements. They have a pleiotropic effect and affect normal renal function. The expression of receptors for melatonin, prolactin, thyrotropin, corticotropin, prostaglandin E1 and trophic factors was confirmed in the kidneys, which suggests that they are a promising therapeutic target for renal IR (ischemia-reperfusion) injury. They can have anti-inflammatory, antioxidant and anti-apoptotic effects, limiting IR injury.

Elevated levels of IL-6 and IGFBP-1 predict low serum IGF-1 levels during continuous infusion of rhIGF-1/rhIGFBP-3 in extremely preterm infants

OBJECTIVE

Steady state insulin-like growth factor-1 (IGF-1) levels vary significantly during continuous intravenous infusion of recombinant human insulin-like growth factor-1/recombinant human insulin-like growth factor binding protein-3 (rhIGF-1/rhIGFBP-3) in the first weeks of life in extremely preterm infants. We evaluated interleukin-6 (IL-6) and insulin-like growth factor binding protein-1 (IGFBP-1) levels as predictors of low IGF-1 levels.

METHODS

Nineteen extremely preterm infants were enrolled in a trial, 9 received rhIGF-1/rhIGFBP-3 and 10 received standard neonatal care. Blood samples were analyzed daily for IGF-1, IL-6 and IGFBP-1 during intervention with rhIGF-1/rhIGFBP-3.

RESULTS

Thirty seven percent of IGF-1 values during active treatment were <20 μg/L. Among treated infants, higher levels of IL-6, one and two days before sampled IGF-1, were associated with IGF-1 < 20 μg/L, gestational age adjusted OR 1.30 (95% CI 1.03-1.63), p = .026, and 1.57 (95% CI 1.26-1.97), p < .001 respectively. Higher levels of IGFBP-1 one day before sampled IGF-1 was also associated with IGF-1 < 20 μg/L, gestational age adjusted OR 1.74 (95% CI 1.19-2.53), p = .004.

CONCLUSION

In preterm infants receiving continuous infusion of rhIGF-1/rhIGFBP-3, higher levels of IL-6 and IGFBP-1 preceded lower levels of circulating IGF-1. These findings demonstrate a need to further evaluate if inflammation and/or infection suppress serum IGF-1 levels. The trial is registered at ClinicalTrials.gov (NCT01096784).

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Plasma Proteome Signature of Sepsis: a Functionally Connected Protein Network

Sepsis is an extreme host response to infection that leads to loss of organ function and cardiovascular integrity. Mortality from sepsis is on the rise. Despite more than three decades of research and clinical trials, specific diagnostic and therapeutic strategies for sepsis are still absent. The use of LFQ- and TMT-based quantitative proteomics is reported here to study the plasma proteome in five mouse models of sepsis. A knowledge-based interpretation of the data reveals a protein network with extensive connectivity through documented functional or physical interactions. The individual proteins in the network all have a documented role in sepsis and are known to be extracellular. The changes in protein abundance observed in the mouse models of sepsis have for the most part the same directionality (increased or decreased abundance) as reported in the literature for human sepsis. This network has been named the Plasma Proteome Signature of Sepsis (PPSS). The PPSS is a quantifiable molecular readout that can supplant the current symptom-based approach used to diagnose sepsis. This type of molecular interpretation of sepsis, its progression, and its response to therapeutic intervention are an important step in advancing our understanding of sepsis, and for discovering and evaluating new therapeutic strategies.

Rare case of meningococcal sepsis-induced testicular failure, primary hypothyroidism and hypoadrenalism: Is there a link?

Severe illness can lead to multiple transient endocrinopathies. In adult patients, neuroendocrine alterations include sick euthyroid syndrome, an increase in corticosteroid levels, increase in prolactin levels, decreased insulin growth factor 1 levels and hypogonadism. We report the case of a 24-year-old man with meningococcal sepsis with multiple end-organ complications who developed persistent non-autoimmune hypothyroidism, adrenal insufficiency and primary hypogonadism all requiring hormone replacement. While adrenal insufficiency as part of the Waterhouse-Friderichsen syndrome is well described, reports of primary hypothyroidism and persistent primary hypogonadism in severe illness are exceedingly rare. Multiple combined endocrinopathies as in this case have not been reported previously. This case highlights the necessity of screening for endocrine abnormalities in severe illness and the need for treatment if persistent. It also raises a novel concept of meningococcal sepsis causing multiple endocrinopathies possibly via disseminated intravascular coagulopathy-related ischaemic damage.

Endocrine and Metabolic Alterations in Sepsis and Implications for Treatment

Sepsis induces profound neuroendocrine and metabolic alterations. During the acute phase, the neuroendocrine changes are directed toward restoration of homeostasis, and also limit unnecessary energy consumption in the setting of restricted nutrient availability. Such changes are probably adaptive. In patients not recovering quickly, a prolonged critically ill phase may ensue, with different neuroendocrine changes, which may represent a maladaptive response. Whether stress hyperglycemia should be aggressively treated or tolerated remains a matter of debate. Until new evidence from randomized controlled trials becomes available, preventing severe hyperglycemia is recommended. Evidence supports withholding parenteral nutrition in the acute phase of sepsis.

Insulin-Like Growth Factors in the Pathogenesis of Neurological Diseases in Children

Insulin-like growth factors play a key role for neuronal growth, differentiation, the survival of neurons and synaptic formation. The action of IGF-1 is most pronounced in the developing brain. In this paper we will try to give an answer to the following questions: Why are studies in children important? What clinical studies in neonatal asphyxia, infantile spasms, progressive encephalopathy-hypsarrhythmia-optical atrophy (PEHO) syndrome, infantile ceroid lipofuscinosis (INCL), autistic spectrum disorders (ASD) and subacute sclerosing encephalopathy (SSPE) have been carried out? What are IGF-based therapeutic strategies? What are the therapeutic approaches? We conclude that there are now great hopes for the therapeutic use of IGF-1 for some neurological disorders (particularly ASD).

Plasma Glycoproteomics Reveals Sepsis Outcomes Linked to Distinct Proteins in Common Pathways

OBJECTIVE

Sepsis remains a predominant cause of mortality in the ICU, yet strategies to increase survival have proved largely unsuccessful. This study aimed to identify proteins linked to sepsis outcomes using a glycoproteomic approach to target extracellular proteins that trigger downstream pathways and direct patient outcomes.

DESIGN

Plasma was obtained from the Lactate Assessment in the Treatment of Early Sepsis cohort. N-linked plasma glycopeptides were quantified by solid-phase extraction coupled with mass spectrometry. Glycopeptides were assigned to proteins using RefSeq (National Center of Biotechnology Information, Bethesda, MD) and visualized in a heat map. Protein differences were validated by immunoblotting, and proteins were mapped for biological processes using Database for Annotation, Visualization and Integrated Discovery (National Institute of Allergy and Infectious Diseases, National Institutes of Health; Bethesda, MD) and for functional pathways using Kyoto Encyclopedia of Genes and Genomes (Kanehisa Laboratories, Kyoto, Japan) databases.

SETTING

Hospitalized care.

PATIENTS

Patients admitted to the emergency department were enrolled in the study when the diagnosis of sepsis was made, within 6 hours of presentation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 501 glycopeptides corresponding to 234 proteins were identified. Of these, 66 glycopeptides were unique to the survivor group and corresponded to 54 proteins, 60 were unique to the nonsurvivor group and corresponded to 43 proteins, and 375 were common responses between groups and corresponded to 137 proteins. Immunoblotting showed that nonsurvivors had increased total kininogen; decreased total cathepsin-L1, vascular cell adhesion molecule, periostin, and neutrophil gelatinase-associated lipocalin; and a two-fold decrease in glycosylated clusterin (all p < 0.05). Kyoto Encyclopedia of Genes and Genomes analysis identified six enriched pathways. Interestingly, survivors relied on the extrinsic pathway of the complement and coagulation cascade, whereas nonsurvivors relied on the intrinsic pathway.

CONCLUSION

This study identifies proteins linked to patient outcomes and provides insight into unexplored mechanisms that can be investigated for the identification of novel therapeutic targets.

αMSH blunts endotoxin-induced MuRF1 and atrogin-1 upregulation in skeletal muscle by modulating NF-κB and Akt/FoxO1 pathway

Alpha melanocyte stimulating hormone (αMSH) has been shown to have anti-inflammatory and anticachectic actions. We hypothesized that αMSH administration could attenuate the effect of lipopolysaccharide (LPS) on the skeletal muscle through modifications in IGF-Akt-FoxO1 pathway, or/and in serum corticosterone. Adult male Wistar rats were injected with LPS and/or αMSH. αMSH administration reduced LPS-induced increase in liver TNFα and serum nitrites as well as NF-κB activation in skeletal muscle. In contrast, αMSH was not able to prevent the stimulatory effect of LPS on serum concentration of ACTH and corticosterone. LPS decreased serum levels of IGF-I and IGFBP3 and their expression in the liver (P < 0.01). However IGFBP3 expression in the gastrocnemius was increased by LPS. Treatment with αMSH prevented the effects of LPS on IGFBP3 but not on IGF-I. In the gastrocnemius αMSH blocked LPS-induced decrease in pAkt as well as the increase in pNF-κB(p65), FoxO1, atrogin-1, and MuRF1 levels. These results suggest that αMSH blunts skeletal muscle response to endotoxin by downregulating atrogenes and FoxO1 at least in part by controlling NF-κB activation and Akt signalling, but not through modifications in the secretion of corticosterone or IGF-I.