Insulin, IGF-1, and IGF-2 receptors in rat small intestine following massive small bowel resection. Analysis by binding, flow cytometry, and immunohistochemistry

Side Effects and Adverse Events After Treatment With Teprotumumab for Thyroid Eye Disease: A Retrospective Observational Case Series

As the use of teprotumumab for thyroid eye disease (TED) becomes more prolific, there remains a scarcity of literature regarding the associated side effects and adverse events of teprotumumab use. The authors present a single-center retrospective, observational case review of TED patients who received at least a single dose of teprotumumab infusion at the oculofacial plastic surgery service between February 2020 and July 2023. The most predominant recollected side effects were fatigue, brittle nails, dry eye symptoms, hair loss, muscle spasms, and dry mouth. Significant adverse events were limited to two cases of a blood clot and a single case of pulmonary embolism. This is the first retrospective study of patient-reported side effects and adverse events experienced by a cohort of teprotumumab users.

Efficacy and safety of recombinant human growth hormone therapy in pediatric intestinal transplant recipients

BACKGROUND

Recombinant human growth hormone (rhGH) is widely used to treat growth retardation in children. We aimed to examine the effect of rhGH therapy on growth and its impact on allograft function in children with growth retardation after intestinal transplant (IT).

METHODS

We retrospectively included children younger than 19 years who had received an IT with or without the liver, were diagnosed with growth retardation, and have received rhGH between January 2010 and January 2021. Changes in the patient's anthropometric parameters between baseline and various time points were compared using the paired t-test or Wilcoxon signed-rank test, as appropriate.

RESULTS

Seven patients (all males and prepubertal) received rhGH for the median duration of 2.3 years. The median age at rhGH start was 9.5 years. The median growth velocity z-score improved from -0.95 before treatment to 2.3 (p = .04) and 1.9 (p = .06) after 1 and 2 years of treatment, respectively. The median height-for-age z-score significantly improved from -3.4 at rhGH start to -1.3 (p = .005) at rhGH stop and remained above baseline at the last visit (-2.4, p = .002). The change in the first-year growth velocity was negatively correlated with the change in the second-year growth velocity (r = -.90, p = .04). No serious adverse effects or worsening allograft function were observed.

CONCLUSIONS

Severely growth retarded children after IT could benefit from rhGH treatment. A larger, longitudinal study would be warranted to monitor the long-term effect and safety of rhGH and examine predictors of growth response to rhGH therapy in these pediatric IT recipients.

Insulin-like growth factor-1 increases bone calcium accumulation only during rapid growth in female rats

Calcium retention varies with developmental state, which may be partially under the control of insulin-like growth factor 1 (IGF-1). IGF-1 levels can be manipulated through dietary and therapeutic interventions. We investigated the relationship between IGF-1 endogenous production and calcium utilization and bone accretion during growth as well as the effects of IGF-1 treatment on calcium utilization during rapid and slowed growth in intact female Sprague-Dawley rats. In 33 rats killed at 11 time points (n = 3 each) from age 4 to 24 wk, femoral and vertebral bone mass were paralleled by plasma IGF-1 up to 9 wk. Fractional calcium absorption was maximal at 9 wk, reduced by one-half at 12 wk, and there was no further change at 20 wk. From this study, we selected 2 stages of growth, rapid and slow, for a subsequent intervention study. A 4-wk intervention was initiated at 6 or 8 wk when rats (n = 15/group) received either continuous rhIGF-1/IGF binding protein 3 (IGFBP3) infusion (0.3 mg/d) or vehicle (control) by osmotic mini-pumps. In rapidly growing IGF-1/IGFBP3-treated rats compared to controls, but not in slowly growing treated compared to control rats, IGF-1 treatment increased (P < 0.05) calcium absorption (35 vs. 21%), bone calcium balance (0.55 vs. 0.3 mmol/d), and femoral calcium content (31 vs. 24% of dry weight). Exogenous IGF-1/IGFBP3 treatment increased calcium accretion during rapid growth, but rats past rapid growth were no longer as sensitive to this dose of IGF-1/IGFBP3. Thus, interventions designed to improve bone mass through increased IGF-1 will have the greatest impact during rapid growth.

Colostrum supplementation restores insulin-like growth factor -1 levels and alters muscle morphology following massive small bowel resection

BACKGROUND

Colostrum protein concentrate (CPC) contains a high level of insulin-like growth factor-1 (IGF-1). IGF-1 and IGF binding protein (IGFBPs) may play an important role during the postresection adaptation response. As smooth muscle is an important site for IGF-1 action in the intestine, this study aims to (1) investigate the effect of CPC supplementation on circulating levels and tissue expression of IGF-1, IGF-1 receptor, and IGFBPs following massive small bowel resection (MSBR), and (2) characterize the effect of CPC on the muscular adaptation response following MSBR.

METHODS

Four-week-old piglets underwent either a 75% MSBR or sham operation. Piglets received either a polymeric infant formula (PIF) diet or PIF supplemented with CPC for 8 weeks. Serum was analyzed by enzyme-linked immunosorbent assay, and ileal tissue assessed by molecular and histological analysis.

RESULTS

There was no difference in IGF-1 or IGFBPs mRNA among groups. CPC treatment resulted in significant increases in circulating levels of IGF-1 and IGFBPs and a concurrent increase in muscle width and the number of muscle cells, but did not alter muscle cell size.

CONCLUSIONS

Strategies aimed at increasing muscular adaptation may decrease Gl transit and allow greater mucosal contact time for absorption. We have shown that CPC supplementation following resection results in increased levels of circulating IGF-1, IGFBP-2, and IGFBP-3 and muscular hypertrophy. Our results suggest that IGF-1 and its mediators may play a role in the muscular adaptation response and warrant further exploration as a treatment option for short bowel syndrome.

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Smooth muscle overexpression of IGF-I induces a novel adaptive response to small bowel resection

Prior studies of intestinal adaptation after massive small bowel resection (SBR) have focused on growth factors and their effects on amplification of the gut mucosa. Because adaptive changes have also been described in intestinal smooth muscle, we sought to determine the effect of targeted smooth muscle growth factor overexpression on resection-induced intestinal adaptation. Male transgenic mice with smooth muscle cell overexpression of insulin-like growth factor I (IGF-I) by virtue of an alpha-smooth muscle actin promoter were obtained. SMP8 IGF-I transgenic (IGF-I TG) and nontransgenic (NT) littermates underwent 50% proximal SBR or sham operation and were then killed after 3 or 28 days. NT mice showed the expected alterations in mucosal adaptive parameters after SBR, such as increased wet weight and villus height. The IGF-I TG mice had inherently taller villi, which did not increase significantly after SBR. In addition, IGF-I TG mice had a 50% postresection persistent increase in remnant intestinal length, which was associated with an early decline and later increase in relative mucosal surface area. These results indicate that growth factor overexpression within the muscularis layer of the bowel wall induces significant postresection adaptive intestinal lengthening and a unique mucosal response. IGF-I signaling within the muscle wall may play an important role in the pathogenesis of resection-induced adaptation.

Jejunal microvilli atrophy and reduced nutrient transport in rats with advanced liver cirrhosis: improvement by Insulin-like Growth Factor I

Background

Previous results have shown that in rats with non-ascitic cirrhosis there is an altered transport of sugars and amino acids associated with elongated microvilli. These alterations returned to normal with the administration of Insulin-Like Growth Factor-I (IGF-I). The aims of this study were to explore the evolution of these alterations and analyse the effect of IGF-I in rats with advanced cirrhosis and ascites. Thus, jejunal structure and nutrient transport (D-galactose, L-leucine, L-proline, L-glutamic acid and L-cystine) were studied in rats with ascitic cirrhosis.

Methods

Advanced cirrhosis was induced by CCl₄ inhalation and Phenobarbital administration for 30 weeks. Cirrhotic animals were divided into two groups which received IGF-I or saline during two weeks. Control group was studied in parallel. Jejunal microvilli were studied by electron microscopy. Nutrient transport was assessed in brush border membrane vesicles using ¹⁴C or ³⁵S-labelled subtracts in the three experimental groups.

Results

Intestinal active Na⁺-dependent transport was significantly reduced in untreated cirrhotic rats. Kinetic studies showed a decreased V_max and a reduced affinity for sugar and four amino acids transporters (expressed as an increased K_t) in the brush border membrane vesicles from untreated cirrhotic rats as compared with controls. Both parameters were normalised in the IGF-I-treated cirrhotic group. Electron microscopy showed elongation and fusion of microvilli with degenerative membrane lesions and/or notable atrophy.

Conclusions

The initial microvilli elongation reported in non ascitic cirrhosis develops into atrophy in rats with advanced cirrhosis and nutrient transports (monosaccharides and amino acids) are progressively reduced. Both morphological and functional alterations improved significantly with low doses of IGF-I.

Distribution of insulin like growth factor-1 (IGF-1) and its receptor in the intestines of the one-humped camel (Camelus dromedarius)

The distribution of insulin-like growth factor-1 (IGF-1) and its receptor in the gut of the one-humped camel (Camelus dromedarius) were studied by immunohistochemistry and quantitative receptor autoradiography. IGF-1-IR cells occurred mainly in the lamina propria and epithelium of the small intestine, while in the large intestine positive cells were seen in the columnar cells of the epithelial layer of colonic glands. IGF-I was also discernible in the muscularis externa of the intestines. Autoradiography revealed a higher concentration of receptors in the mucosa compared to the muscular layer. With regard to the mucosa, the highest density of receptors was discernible in the duodenum. Immunohistochemistry revealed the main sites of the receptors to be the lamina propria, epithelia of the crypts and the villi of intestines. Double immunofluorescence studies with combined antisera to IGF-I and its receptor showed that the ligand and its receptor usually occurred within the same cell in the mucosa. A few cells with varied profiles immunoreacted to either the ligand or the receptor but not to both. Cells with varied profiles immunoreacted to antiserum of the receptors but not to the ligand in the muscle layer. Thus IGF-1 might be acting on its receptor via both an autocrine and paracrine modes in the camel mucosa. In the muscularis layer, IGF-1 may be acting by different mechanisms. Our data demonstrate that unlike all other mammals studied, the camel contains a high concentration of IGF-1 receptors in the duodenal mucosa compared to other parts of the camel gut. It also possesses a higher concentration of the receptor in its mucosa compared to the muscle layer. We speculate that this might be a significant feature necessary for the regenerative ability of the duodenal mucosa in the one-humped camel.

The role of receptor tyrosine kinase inhibition in treating gastrointestinal malignancy

Tyrosine kinase receptors are proteins that transduce the signal from many growth factor and cytokine ligands to produce intracellular responses. As such they can activate multiple signalling cascade pathways and influence cell division, migration and survival. Many show upregulation in certain malignancies, including those of the gastrointestinal tract, and are thought to play key roles in carcinogenesis. This makes them attractive targets for drug therapy and in recent years many inhibitors have been developed. This review discusses the current situation regarding the development of inhibitors with particular reference to the erbB family, the insulin-like growth factor receptor, the Met receptor, the receptor for vascular endothelial growth factor and the Kit receptor. The evidence will be related back to cancers of the gut lumen. Clinical effectiveness in this area seems to lie in using a combinatorial approach that inhibits multiple key signalling points, and the reasons for this will be discussed.

Altered intestinal transport of amino acids in cirrhotic rats: the effect of insulin-like growth factor-I

The intestine is an important target organ for insulin-like growth factor-I (IGF-I), an anabolic hormone synthesized in the liver upon growth hormone (GH) stimulation. Levels of IGF-I are reduced in cirrhosis, and altered GH/IGF-I axis may contribute to malnutrition in cirrhotic patients. Our aim was to study Na(+)-dependent jejunal transport of amino acids (L-leucine, L-proline, L-glutamic acid, and L-cysteine) in cirrhotic rats and to analyze the effect of IGF-I on this function. IGF-I or saline was administered for 2 wk to rats with CCl(4)-induced cirrhosis and saline was administered to healthy control rats. Transport of amino acids was assessed in brush-border membrane vesicles (BBMV) using (14)C- or (35)S-labeled amino acids, and the kinetic constants V(max) and K(t) were determined. Na(+)-independent uptake of L-leucine, L-proline, L-glutamic acid, and L-cysteine by BBMV was similar in all groups. Na(+)-dependent uptake of all four amino acids was significantly diminished in cirrhotic rats compared with both controls and IGF-I-treated cirrhotic rats. The latter two groups exhibited similar V(max) and K(t), whereas untreated cirrhotic rats had reduced V(max) and increased K(t) compared with normal controls and IGF-I-treated cirrhotic animals. In conclusion, the transport of all four tested amino acids by BBMV is impaired in cirrhotic rats, and low doses of IGF-I can correct this defect.

Investigation of insulin-like growth factor (IGF)-I and insulin receptor binding and expression in jejunum of parenterally fed rats treated with IGF-I or growth hormone

To investigate the ability of insulin-like growth factor-I (IGF-I), but not GH, to stimulate jejunal growth, we compared indices of IGF-I and insulin receptor expression in jejunal membranes from rats maintained with total parenteral nutrition (TPN) and treated with rhIGF-I and/or rhGH. TPN without growth factor treatment (TPN control) induced jejunal atrophy, reduced serum IGF-I, increased serum insulin concentrations, and increased IGF-I receptor number, IGF-I receptor messenger RNA, and insulin-specific binding to 133% to 170% of the orally fed reference values, P < 0.01. Compared with TPN control, IGF-I or IGF-I + GH stimulated jejunal mucosal hyperplasia; IGF-I treatment increased serum IGF-I by 2- to 3-fold and decreased serum insulin concentrations by 60%, decreased IGF-I receptor number by 50% (P < 0.001), and increased insulin receptor affinity and insulin receptor protein content. Treatment with GH alone increased serum IGF-I concentration, did not alter TPN-induced jejunal atrophy, and decreased insulin-specific binding and insulin receptor protein content (39% and 59%, respectively, of the TPN control values, P < 0.01). We conclude that: 1) jejunal IGF-I receptor content reflects circulating concentration of ligand and is not limiting for jejunal growth; and 2) increased circulating concentration of IGF-I may promote jejunal growth via interaction with jejunal insulin or IGF-I receptors.

The effect of enhanced milk yield of dairy cows by frequent milking or suckling on intake and digestibility of the diet

Groups of 9 or 10 cows were assigned to one of three treatments 1) machine-milking three times daily, 2) machine-milking six times daily, and 3) suckling three times daily in addition to machine-milking three times daily. Treatments were conducted during the first 6 wk postpartum. During wk 5, digestibility of the diet was estimated by the indigestible neutral detergent fiber method. During wk 6, milk yield and dry matter intake (DMI) were recorded daily, and plasma concentrations of glucose, nonesterified fatty acids, urea, protein, growth hormone, insulin, insulin-like growth factor I, oxytocin, and prolactin were determined. Milk yields were 38.5, 46.8, and 52.7 kg/d, and DMI were 18.1, 21.2, and 17.2, for cows on treatments 1, 2, and 3, respectively. Plasma glucose concentrations decreased, and plasma nonesterified fatty acid concentrations increased, for cows on treatments 2 and 3 compared with cows on treatment 1. Digestibility of dry matter was 57.5, 60.5, and 60.6%; of organic matter was 62.6, 64.6, and 66.8%; and of crude protein was 59.3, 62.7, and 64.6% for cows on treatments 1, 2, and 3, respectively. Concentrations of all assayed hormones, except insulin, increased moderately for cows on treatment 2 compared with cows on treatment 1 and increased dramatically for cows on treatment 3. Insulin concentrations followed the opposite trend. The DMI were positively related to milk yields and negatively related to oxytocin concentrations. Digestibility was negatively related to plasma glucose concentrations in a nonlinear pattern. The possible involvement of hormones in improvement of digestibility is discussed.

Effect of growth factors on epithelial restitution of human colonic mucosa in vitro

BACKGROUND

Epithelial restitution enables resurfacing of epithelial discontinuities by enterocyte migration. This study investigated the effect of basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF-1), and epidermal growth factor (EGF) on restitution of human colonic mucosa in vitro.

METHODS

After base-line incubation human colonic mucosal strips, mounted in Ussing chambers, were luminally exposed to 0.5 mM sodium deoxycholate (NaDOC) for 10 min. Thereafter tissues were incubated with buffer alone or luminal buffer containing various concentrations of bFGF, IGF-1, and EGF for 3 h. Resistance (R) was calculated from potential difference (PD) and short-circuit current (Isc). All tissues were processed for light microscopy. Extent of damage was measured by morphometry.

RESULTS

Luminal 0.5 mM NaDOC for 10 min caused R to drop by 43% (n = 4; P < 0.05). Compared with controls 50 ng/ml EGF induced an approximately 30% R increase until the end of the experiments (P < 0.05, n = 4, paired). Ten minutes after injury 50.2 +/- 4% of the mucosa was damaged (n = 6), and after 3 h damage was significantly reduced by EGF (17.2 +/- 3% versus 31.7 +/- 4%, 50 ng/ml EGF versus controls) (P < 0.05, n = 6 per group). Histology showed that EGF stimulated enterocyte migration over the basal lamina. Various doses of bFGF and IGF-1 did not impair restitution when compared with controls.

CONCLUSION

In contrast to bFGF and IGF-1, EGF was shown to promote epithelial restitution of human colonic mucosa in vitro.

IP6: a novel anti-cancer agent

Inositol hexaphosphate (InsP6 or IP6) is ubiquitous. At 10 microM to 1 mM concentrations, IP6 and its lower phosphorylated forms (IP(1-5)) as well as inositol (Ins) are contained in most mammalian cells, wherein they are important in regulating vital cellular functions such as signal transduction, cell proliferation and differentiation. A striking anti-cancer action of IP6 has been demonstrated both in vivo and in vitro, which is based on the hypotheses that exogenously administered IP6 may be internalized, dephosphorylated to IP(1-5), and inhibit cell growth. There is additional evidence that Ins alone may further enhance the anti-cancer effect of IP6. Besides decreasing cellular proliferation, IP6 also causes differentiation of malignant cells often resulting in a reversion to normal phenotype. These data strongly point towards the involvement of signal transduction pathways, cell cycle regulatory genes, differentiation genes, oncogenes and perhaps, tumor suppressor genes in bringing about the observed anti-neoplastic action of IP6.

Insulin-like growth factor-I (IGF-I) mRNA in the small intestine of suckling and adult rats

The presence and cellular localization of insulin-like growth factor-I (IGF-I) mRNA in the small intestine of suckling and adult rats was studied. A sensitive reverse transcription (RT) competitive-polymerase chain reaction (PCR) revealed IGF-I gene expression in both age groups. Adult tissue contained 3-fold higher levels of IGF-I mRNA in comparison with sucklings. Using an in situ hybridization technique, IGF-I transcripts were localized mainly in enterocytes and goblet cells in the intestinal crypts of adult rats. By using this technique, IGF-I mRNA was not detected in jejunum of 12-day-old rats.

Administration of insulin-like growth factor-I (IGF-I) peptides for three days stimulates proliferation of the small intestinal epithelium in rats

It has previously been shown that longterm administration of insulin-like growth factor-I (IGF-I) or the analogue Long R3 IGF-I (LR3IGF-I) selectively stimulate growth of the gastrointestinal tract in gut resected, dexamethasone treated, and normal rats. In this study, the short-term effects of IGF-I administration on intestinal proliferation have been investigated. Female rats (110 g, five-six/group) were infused for three days with 2.5 mg/kg/day of either IGF-I or LR3IGF-I and compared with vehicle treated or untreated control rats. LR3IGF-I but not IGF-I increased body weight and wet tissue weight of the small and large intestine (+20%), compared with controls. Tissue weight responses were independent of food intake and were reflected in the histology of the tissue. In LR3IGF-I treated animals, duodenal and ileal crypts length were increased by 13 and 22%, respectively, associated with an increase in crypt cell number. No such histological changes were seen in IGF-I treated rats. Tritiated thymidine labelling indices were significantly increased after administration of either IGF-I or LR3IGF-I (up to 14%) in both the duodenum and ileum. In IGF-I treated rats, increased nuclear labelling was not associated with an increase in the crypt compartment. In contrast, LR3IGF-I induced proportional increments in thymidine labelling and crypt size, suggesting that LR3IGF-I is not only more potent than the native peptide but also induced proliferative events more rapidly. In the colon, the thymidine labelling index was low, however, a non-significant increase in the number of cells labelled with thymidine was seen. These results suggest that within a three day treatment period intestinal mitogenesis is more advanced in animals treated with LR3IGF-I. The differences in proliferative response between the two peptides may be accounted for by variations in pharmacokinetics, clearance rates, and interactions with circulating and tissue specific binding proteins.