Insulin-like growth factor I acts as an angiogenic agent in rabbit cornea and retina: comparative studies with basic fibroblast growth factor

Corneal parameters, ocular biometers, and retinal and choroidal thickness in acromegaly patients

BACKGROUND

To compare ocular findings of acromegaly patients with healthy individuals and investigate the relation of serum levels of insulin-like growth factor (IGF-1) along with growth hormone (GH) and pituitary tumor (adenoma) dimensions (TD) with specific ocular parameters.

METHODS

The ocular parameters of acromegaly patients (n = 38) were compared with those of healthy subjects (n = 36). These parameters were intraocular pressure, keratometric (K1-K2) values, central corneal thickness (CCT), total axial length along with anterior chamber-lens-vitreous length, retinal nerve fiber layer (RNFL) thickness, central foveal thickness (CFT), choroidal thickness (CT), ganglion cell layer thickness (GCLT), and inner plexiform layer thickness (IPLT). Also investigated was whether there was a correlation between disease duration, TD, GH, IGF-I, CCT, RNFL, CFT, GCLT, IPLT, and CT.

RESULTS

The lens length of the acromegaly group was increased (p = 0.014). GH and IGF-1 levels were positively correlated with CT and CCT, respectively (p = 0.041, r = 0.343) (p = 0.03, r = 0.347). Analysis of TD also found a highly negative correlation with the mean RNFL thickness of the acromegaly patients (p < 0.01, r = -0.603). The mean value of the inner parts of GCLT and IPLT was negatively correlated with TD (p = 0.041, r = -0.343 and p = 0.025, r = -0.379, respectively).

CONCLUSION

Serum IGF-1 and GH levels might be determinant factors in CCT and CT, respectively. The pituitary adenoma size increasing may be prone to lead RNFL, ganglion cell layer, inner plexiform layer thinning. Increased lens thickness was found in the acromegaly group.

The interplay of oxidative stress and ARMS2-HTRA1 genetic risk in neovascular AMD

Age-related macular degeneration (AMD) is the leading cause of vision loss in adults over 60 years old globally. There are two forms of advanced AMD: “dry” and “wet”. Dry AMD is characterized by geographic atrophy of the retinal pigment epithelium and overlying photoreceptors in the macular region; whereas wet AMD is characterized by vascular penetrance from the choroid into the retina, known as choroidal neovascularization (CNV). Both phenotypes eventually lead to loss of central vision. The pathogenesis of AMD involves the interplay of genetic polymorphisms and environmental risk factors, many of which elevate retinal oxidative stress. Excess reactive oxygen species react with cellular macromolecules, forming oxidation-modified byproducts that elicit chronic inflammation and promote CNV. Additionally, genome-wide association studies have identified several genetic variants in the age-related maculopathy susceptibility 2/high-temperature requirement A serine peptidase 1 (ARMS2-HTRA1) locus associated with the progression of late-stage AMD, especially the wet subtype. In this review, we will focus on the interplay of oxidative stress and HTRA1 in drusen deposition, chronic inflammation, and chronic angiogenesis. We aim to present a multifactorial model of wet AMD progression, supporting HTRA1 as a novel therapeutic target upstream of vascular endothelial growth factor (VEGF), the conventional target in AMD therapeutics. By inhibiting HTRA1’s proteolytic activity, we can reduce pro-angiogenic signaling and prevent proteolytic breakdown of the blood-retina barrier. The anti-HTRA1 approach offers a promising alternative treatment option to wet AMD, complementary to anti-VEGF therapy.

In Ovo and In Silico Evaluation of the Anti-Angiogenic Potential of Syringin

INTRODUCTION

Cancer is considered as one of the deadliest human diseases today. Angiogenesis, the propagation of new blood vessels from pre-existing vasculature, is a critical step in the progression of cancer as it is essential in the growth and metastasis of tumors. Hence, suppression of angiogenesis is a promising approach in cancer therapy. Syringin, a phenylpropanoid glycoside with a molecular formula of C17H24O9, has been found to exhibit chemopreventive effects. However, its anti-angiogenic activity and the underlying mechanism of action are still unknown.

METHODS

In this work, in ovo chorioallantoic membrane (CAM) assay has been conducted to evaluate the effect of syringin on neovascularization. Additionally, reverse molecular docking studies have been performed in order to identify the probable enzyme targets in the angiogenesis pathway.

RESULTS

Treatment with syringin showed significant dose-dependent inhibition of blood vessel length and junctions in the CAM of duck eggs; the anti-angiogenic activity of syringin at 100 µM and 200 µM is comparable with 200 µM of the positive control celecoxib. The results of reverse docking studies indicate that syringin binds the strongest to dihydrofolate reductase (DHFR) and, to some extent, with transforming growth factor-beta receptor type 1 (TGF-βR1), vascular endothelial growth factor receptor 2 (VEGFR2), and matrix metalloproteinase-2 (MMP-2). Furthermore, ADMET models revealed that syringin potentially possesses excellent pharmacokinetic and toxicity profiles.

CONCLUSION

This study demonstrates the potential of syringin as an anti-angiogenic agent and elicits further investigations to establish its application in cancer suppression.

(Ultra-)long-acting insulin analogues versus NPH insulin (human isophane insulin) for adults with type 2 diabetes mellitus

BACKGROUND

Evidence that antihyperglycaemic therapy is beneficial for people with type 2 diabetes mellitus is conflicting. While the United Kingdom Prospective Diabetes Study (UKPDS) found tighter glycaemic control to be positive, other studies, such as the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial, found the effects of an intensive therapy to lower blood glucose to near normal levels to be more harmful than beneficial. Study results also showed different effects for different antihyperglycaemic drugs, regardless of the achieved blood glucose levels. In consequence, firm conclusions on the effect of interventions on patient-relevant outcomes cannot be drawn from the effect of these interventions on blood glucose concentration alone. In theory, the use of newer insulin analogues may result in fewer macrovascular and microvascular events.

OBJECTIVES

To compare the effects of long-term treatment with (ultra-)long-acting insulin analogues (insulin glargine U100 and U300, insulin detemir and insulin degludec) with NPH (neutral protamine Hagedorn) insulin (human isophane insulin) in adults with type 2 diabetes mellitus.

SEARCH METHODS

For this Cochrane Review update, we searched CENTRAL, MEDLINE, Embase, ICTRP Search Portal and ClinicalTrials.gov. The date of the last search was 5 November 2019, except Embase which was last searched 26 January 2017. We applied no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing the effects of treatment with (ultra-)long-acting insulin analogues to NPH in adults with type 2 diabetes mellitus.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed risk of bias, extracted data and evaluated the overall certainty of the evidence using GRADE. Trials were pooled using random-effects meta-analyses.

MAIN RESULTS

We identified 24 RCTs. Of these, 16 trials compared insulin glargine to NPH insulin and eight trials compared insulin detemir to NPH insulin. In these trials, 3419 people with type 2 diabetes mellitus were randomised to insulin glargine and 1321 people to insulin detemir. The duration of the included trials ranged from 24 weeks to five years. For studies, comparing insulin glargine to NPH insulin, target values ranged from 4.0 mmol/L to 7.8 mmol/L (72 mg/dL to 140 mg/dL) for fasting blood glucose (FBG), from 4.4 mmol/L to 6.6 mmol/L (80 mg/dL to 120 mg/dL) for nocturnal blood glucose and less than 10 mmol/L (180 mg/dL) for postprandial blood glucose, when applicable. Blood glucose and glycosylated haemoglobin A1c (HbA1c) target values for studies comparing insulin detemir to NPH insulin ranged from 4.0 mmol/L to 7.0 mmol/L (72 mg/dL to 126 mg/dL) for FBG, less than 6.7 mmol/L (120 mg/dL) to less than 10 mmol/L (180 mg/dL) for postprandial blood glucose, 4.0 mmol/L to 7.0 mmol/L (72 mg/dL to 126 mg/dL) for nocturnal blood glucose and 5.8% to less than 6.4% HbA1c, when applicable. All trials had an unclear or high risk of bias for several risk of bias domains. Overall, insulin glargine and insulin detemir resulted in fewer participants experiencing hypoglycaemia when compared with NPH insulin. Changes in HbA1c were comparable for long-acting insulin analogues and NPH insulin. Insulin glargine compared to NPH insulin had a risk ratio (RR) for severe hypoglycaemia of 0.68 (95% confidence interval (CI) 0.46 to 1.01; P = 0.06; absolute risk reduction (ARR) -1.2%, 95% CI -2.0 to 0; 14 trials, 6164 participants; very low-certainty evidence). The RR for serious hypoglycaemia was 0.75 (95% CI 0.52 to 1.09; P = 0.13; ARR -0.7%, 95% CI -1.3 to 0.2; 10 trials, 4685 participants; low-certainty evidence). Treatment with insulin glargine reduced the incidence of confirmed hypoglycaemia and confirmed nocturnal hypoglycaemia. Treatment with insulin detemir compared to NPH insulin found an RR for severe hypoglycaemia of 0.45 (95% CI 0.17 to 1.20; P = 0.11; ARR -0.9%, 95% CI -1.4 to 0.4; 5 trials, 1804 participants; very low-certainty evidence). The Peto odds ratio for serious hypoglycaemia was 0.16, 95% CI 0.04 to 0.61; P = 0.007; ARR -0.9%, 95% CI -1.1 to -0.4; 5 trials, 1777 participants; low-certainty evidence). Treatment with detemir also reduced the incidence of confirmed hypoglycaemia and confirmed nocturnal hypoglycaemia. Information on patient-relevant outcomes such as death from any cause, diabetes-related complications, health-related quality of life and socioeconomic effects was insufficient or lacking in almost all included trials. For those outcomes for which some data were available, there were no meaningful differences between treatment with glargine or detemir and treatment with NPH. There was no clear difference between insulin-analogues and NPH insulin in terms of weight gain. The incidence of adverse events was comparable for people treated with glargine or detemir, and people treated with NPH. We found no trials comparing ultra-long-acting insulin glargine U300 or insulin degludec with NPH insulin.

AUTHORS' CONCLUSIONS

While the effects on HbA1c were comparable, treatment with insulin glargine and insulin detemir resulted in fewer participants experiencing hypoglycaemia when compared with NPH insulin. Treatment with insulin detemir also reduced the incidence of serious hypoglycaemia. However, serious hypoglycaemic events were rare and the absolute risk reducing effect was low. Approximately one in 100 people treated with insulin detemir instead of NPH insulin benefited. In the studies, low blood glucose and HbA1c targets, corresponding to near normal or even non-diabetic blood glucose levels, were set. Therefore, results from the studies are only applicable to people in whom such low blood glucose concentrations are targeted. However, current guidelines recommend less-intensive blood glucose lowering for most people with type 2 diabetes in daily practice (e.g. people with cardiovascular diseases, a long history of type 2 diabetes, who are susceptible to hypoglycaemia or older people). Additionally, low-certainty evidence and trial designs that did not conform with current clinical practice meant it remains unclear if the same effects will be observed in daily clinical practice. Most trials did not report patient-relevant outcomes.

Synergy Between Low Dose Metronomic Chemotherapy and the pH-centered Approach Against Cancer

Low dose metronomic chemotherapy (MC) is becoming a mainstream treatment for cancer in veterinary medicine. Its mechanism of action is anti-angiogenesis by lowering vascular endothelial growth factor (VEGF) and increasing trombospondin-1 (TSP1). It has also been adopted as a compassionate treatment in very advanced human cancer. However, one of the main limitations of this therapy is its short-term effectiveness: 6 to 12 months, after which resistance develops. pH-centered cancer treatment (pHT) has been proposed as a complementary therapy in cancer, but it has not been adopted or tested as a mainstream protocol, in spite of existing evidence of its advantages and benefits. Many of the factors directly or indirectly involved in MC and anti-angiogenic treatment resistance are appropriately antagonized by pHT. This led to the testing of an association between these two treatments. Preliminary evidence indicates that the association of MC and pHT has the ability to reduce anti-angiogenic treatment limitations and develop synergistic anti-cancer effects. This review will describe each of these treatments and will analyze the fundamentals of their synergy.

Age-Related Alterations in Retinal Tissue Perfusion and Volumetric Vessel Density

Purpose

To determine age-related alterations in the retinal tissue perfusion (RTP) and volumetric vessel density (VVD) in healthy subjects.

Methods

Total 148 healthy subjects (age 18 to 83 years) were enrolled and divided into four groups (G1, <35 years; G2, 35 ∼ 49 years; G3, 50 ∼ 64 years; and G4, ≥65 years). The RTP and VVD were measured at the macula. The RTP was calculated as the blood flow supplying the macular area (ϕ 2.5 mm) divided by the perfused tissue volume of the inner retina from the inner limiting membrane to the outer plexiform layer. The VVD of the macula (ϕ 2.5 mm) was calculated as the vessel density divided by the corresponding tissue volume.

Results

The RTP and VVD of the retinal vascular network and deep vascular plexus (DVP) reached a peak in G2. Compared to G2, G4 had significantly lower RTP and VVD of DVP (P < 0.05). After 35 years old, age was negatively related to the RTP (r = −0.26, P = 0.02) and VVD of the DVP (r = −0.47, P < 0.001). However, age was positively related to VVD of the superficial vascular plexus (SVP; r = 0.24, P = 0.04) in subjects aged more than 35 years. The RTP was correlated to VVD measurements (r = 0.23–0.37, P < 0.01).

Conclusions

This is the first study to reveal the age-related alterations in the RTP and VVD during normal aging in a healthy population. Decreased RTP and VVD in the DVP along with increased VVD in the SVP may represent a characteristic pattern of normal aging in the healthy population.

The impact of hyperglycemia on the corneal epithelium: Molecular mechanisms and insight

Type 2 Diabetes Mellitus (T2DM) is reaching epidemic levels worldwide and with it, there is a significant increase in complications associated with the disease. T2DM affects virtually all organ systems including the eye. While frequently overlooked, diabetic keratopathy is the most common ocular complication of diabetes and can manifest in mild to severe forms, the latter of which poses a major threat to vision. As the initial barrier between the environment and the eye, the corneal epithelium functions in innate immune defense. Compromise of this barrier may predispose the cornea to infection and can hinder the refractive capabilities of the eye. The clinical burden in patients with diabetic keratopathy lies primarily in the inability of the corneal epithelium to repair damage and maintain its tight barrier function. Current therapies for diabetic keratopathy are supportive, centering on the prevention of infection and promotion of an optimal healing environment. With no clear disease-modifying agent identified as of yet, a thorough understanding of the pathophysiology that underlies the development of diabetic keratopathy at the cellular level is critical to identify and develop potential therapeutic agents capable of promoting corneal re-epithelialization to accelerate the wound healing process. The focus of this review is to examine what is known regarding the cellular and molecular mechanisms needed to maintain epithelial homeostasis and how it goes awry in diabetes.

Circulating insulin-like growth factor-1: a new clue in the pathogenesis of age-related macular degeneration

In order to investigate Insulin-like growth factor-1 (IGF-1) blood levels in male and female age-matched patients affected by early, intermediate, neovascular age related macular degeneration (AMD) and healthy subjects (no AMD) were enrolled in a prospective, observational study. All patients enrolled were classified according to 4 stages classification of AMD from Age-related eye disease study (AREDS). Each subject underwent a complete ophthalmic examination including best corrected visual acuity (BCVA), applanation tonometry, slit-lamp biomicroscopic examination, color fundus photography, optical coherence tomography (OCT) and, if needed, fluorescein angiography. Overall, 224 anti-VEGF naïve subjects including 56 patients in early AMD group, 56 patients in intermediate AMD group, 56 patients in neovascular AMD group and 56 patients in no AMD group were recruited. For each group 28 male patients and 28 female patients were enrolled. IGF-1 hematic levels were significantly higher (p<0.005) in the neovascular AMD group and in the intermediate AMD group in comparison to no AMD group; no significant difference between early AMD group and no AMD group was found. Our analysis has shown an increment of IGF-1 levels in both neovascular and intermediate stage of AMD supporting the hypothesis that IGF-1 may play a role in the pathogenesis of AMD.

Circulating insulin-like growth factor-1: a new clue in the pathogenesis of age-related macular degeneration

In order to investigate Insulin-like growth factor-1 (IGF-1) blood levels in male and female age-matched patients affected by early, intermediate, neovascular age related macular degeneration (AMD) and healthy subjects (no AMD) were enrolled in a prospective, observational study. All patients enrolled were classified according to 4 stages classification of AMD from Age-related eye disease study (AREDS). Each subject underwent a complete ophthalmic examination including best corrected visual acuity (BCVA), applanation tonometry, slit-lamp biomicroscopic examination, color fundus photography, optical coherence tomography (OCT) and, if needed, fluorescein angiography. Overall, 224 anti-VEGF naïve subjects including 56 patients in early AMD group, 56 patients in intermediate AMD group, 56 patients in neovascular AMD group and 56 patients in no AMD group were recruited. For each group 28 male patients and 28 female patients were enrolled. IGF-1 hematic levels were significantly higher (p<0.005) in the neovascular AMD group and in the intermediate AMD group in comparison to no AMD group; no significant difference between early AMD group and no AMD group was found. Our analysis has shown an increment of IGF-1 levels in both neovascular and intermediate stage of AMD supporting the hypothesis that IGF-1 may play a role in the pathogenesis of AMD.

Short-acting insulin analogues versus regular human insulin for adult, non-pregnant persons with type 2 diabetes mellitus

BACKGROUND

The use of short-acting insulin analogues (insulin lispro, insulin aspart, insulin glulisine) for adult, non-pregnant people with type 2 diabetes is still controversial, as reflected in many scientific debates.

OBJECTIVES

To assess the effects of short-acting insulin analogues compared to regular human insulin in adult, non-pregnant people with type 2 diabetes mellitus.

SEARCH METHODS

For this update we searched CENTRAL, MEDLINE, Embase, the WHO ICTRP Search Portal, and ClinicalTrials.gov to 31 October 2018. We placed no restrictions on the language of publication.

SELECTION CRITERIA

We included all randomised controlled trials with an intervention duration of at least 24 weeks that compared short-acting insulin analogues to regular human insulin in the treatment of people with type 2 diabetes, who were not pregnant.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias. We assessed dichotomous outcomes by risk ratios (RR), and Peto odds ratios (POR), with 95% confidence intervals (CI). We assessed continuous outcomes by mean differences (MD) with 95% CI. We assessed trials for certainty of the evidence using the GRADE approach.

MAIN RESULTS

We identified 10 trials that fulfilled the inclusion criteria, randomising 2751 participants; 1388 participants were randomised to receive insulin analogues and 1363 participants to receive regular human insulin. The duration of the intervention ranged from 24 to 104 weeks, with a mean of about 41 weeks. The trial populations showed diversity in disease duration, and inclusion and exclusion criteria. None of the trials were blinded, so the risk of performance bias and detection bias, especially for subjective outcomes, such as hypoglycaemia, was high in nine of 10 trials from which we extracted data. Several trials showed inconsistencies in the reporting of methods and results.None of the included trials defined all-cause mortality as a primary outcome. Six trials provided Information on the number of participants who died during the trial, with five deaths out of 1272 participants (0.4%) in the insulin analogue groups and three deaths out of 1247 participants (0.2%) in the regular human insulin groups (Peto OR 1.66, 95% CI 0.41 to 6.64; P = 0.48; moderate-certainty evidence). Six trials, with 2509 participants, assessed severe hypoglycaemia differently, therefore, we could not summarise the results with a meta-analysis. Overall, the incidence of severe hypoglycaemic events was low, and none of the trials showed a clear difference between the two intervention arms (low-certainty evidence).The MD in glycosylated haemoglobin A1c (HbA1c) change was -0.03% (95% CI -0.16 to 0.09; P = 0.60; 9 trials, 2608 participants; low-certainty evidence). The 95% prediction ranged between -0.31% and 0.25%. The MD in the overall number of non-severe hypoglycaemic episodes per participant per month was 0.08 events (95% CI 0.00 to 0.16; P = 0.05; 7 trials, 2667 participants; very low-certainty evidence). The 95% prediction interval ranged between -0.03 and 0.19 events per participant per month. The results provided for nocturnal hypoglycaemic episodes were of questionable validity. Overall, there was no clear difference between the two short-acting insulin analogues and regular human insulin. Two trials assessed health-related quality of life and treatment satisfaction, but we considered the results for both outcomes to be unreliable (very low-certainty evidence).No trial was designed to investigate possible long term effects (all-cause mortality, microvascular or macrovascular complications of diabetes), especially in participants with diabetes-related complications. No trial reported on socioeconomic effects.

AUTHORS' CONCLUSIONS

Our analysis found no clear benefits of short-acting insulin analogues over regular human insulin in people with type 2 diabetes. Overall, the certainty of the evidence was poor and results on patient-relevant outcomes, like all-cause mortality, microvascular or macrovascular complications and severe hypoglycaemic episodes were sparse. Long-term efficacy and safety data are needed to draw conclusions about the effects of short-acting insulin analogues on patient-relevant outcomes.

Angiogenic growth factors in myocardial infarction: a critical appraisal

In the recent past, substantial advances have been made in the treatment of myocardial infarction (MI). Despite the impact of these positive developments, MI remains to be a leading cause of morbidity as well as mortality. An interesting hypothesis is that the development of new blood vessels (angiogenesis) or the remodeling of preexisting collaterals may form natural bypasses that could compensate for the occlusion of an epicardial coronary artery. A number of angiogenic factors are proven to be elicited during MI. Exogenous supplementation of these growth factors either in the form of recombinant protein or gene would enhance the collateral vessel formation and thereby improve the outcome after MI. The aim of this review is to describe the nature and potentials of different angiogenic factors, their expression, their efficacy in animal studies, and clinical trials pertaining to MI.

IGF2 and IGF1R identified as novel tip cell genes in primary microvascular endothelial cell monolayers

Tip cells, the leading cells of angiogenic sprouts, were identified in cultures of human umbilical vein endothelial cells (HUVECs) by using CD34 as a marker. Here, we show that tip cells are also present in primary human microvascular endothelial cells (hMVECs), a more relevant endothelial cell type for angiogenesis. By means of flow cytometry, immunocytochemistry, and qPCR, it is shown that endothelial cell cultures contain a dynamic population of CD34⁺ cells with many hallmarks of tip cells, including filopodia-like extensions, elevated mRNA levels of known tip cell genes, and responsiveness to stimulation with VEGF and inhibition by DLL4. Furthermore, we demonstrate that our in vitro tip cell model can be exploited to investigate cellular and molecular mechanisms in tip cells and to discover novel targets for anti-angiogenesis therapy in patients. Small interfering RNA (siRNA) was used to knockdown gene expression of the known tip cell genes angiopoietin 2 (ANGPT2) and tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (TIE1), which resulted in similar effects on tip cells and sprouting as compared to inhibition of tip cells in vivo. Finally, we identified two novel tip cell-specific genes in CD34⁺ tip cells in vitro: insulin-like growth factor 2 (IGF2) and IGF-1-receptor (IGF1R). Knockdown of these genes resulted in a significant decrease in the fraction of tip cells and in the extent of sprouting in vitro and in vivo. In conclusion, this study shows that by using our in vitro tip cell model, two novel essential tip cells genes are identified.

Biomarkers of Diabetic Retinopathy

Diabetic retinopathy (DR), a leading cause of acquired vision loss, is a microvascular complication of diabetes. While traditional risk factors for diabetic retinopathy including longer duration of diabetes, poor blood glucose control, and dyslipidemia are helpful in stratifying patient's risk for developing retinopathy, many patients without these traditional risk factors develop DR; furthermore, there are persons with long diabetes duration who do not develop DR. Thus, identifying biomarkers to predict DR or to determine therapeutic response is important. A biomarker can be defined as a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. Incorporation of biomarkers into risk stratification of persons with diabetes would likely aid in early diagnosis and guide treatment methods for those with DR or with worsening DR. Systemic biomarkers of DR include serum measures including genomic, proteomic, and metabolomics biomarkers. Ocular biomarkers including tears and vitreous and retinal vascular structural changes have also been studied extensively to prognosticate the risk of DR development. The current studies on biomarkers are limited by the need for larger sample sizes, cross-validation in different populations and ethnic groups, and time-efficient and cost-effective analytical techniques. Future research is important to explore novel DR biomarkers that are non-invasive, rapid, economical, and accurate to help reduce the incidence and progression of DR in people with diabetes.

Retina ganglion cell/inner plexiform layer and peripapillary nerve fiber layer thickness in patients with acromegaly

Increased secretion of growth hormone and insulin-like growth factor-1 in acromegaly has various effects on multiple organs. However, the ocular effects of acromegaly have yet to be investigated in detail. The aim of the present study was to compare retina ganglion cell/inner plexiform layer (GCIPL) and peripapillary nerve fiber layer thickness (pRNFL) between patients with acromegaly and healthy control subjects using spectral domain optical coherence tomography (SD-OCT). This cross-sectional, comparative study included 18 patients with acromegaly and 20 control subjects. All participants underwent SD-OCT to measure pRNFL (in the seven peripapillary areas), GCIPL (in the nine ETDRS areas), and central macular thickness (CMT). Visual field (VF) examinations were performed using a Humphrey field analyzer in acromegalic patients. Measurements were compared between patients with acromegaly and control subjects. A total of 33 eyes of 18 patients with acromegaly and 40 eyes of 20 control subjects met the inclusion criteria of the present study. The overall calculated average pRNFL thickness was significantly lower in patients with acromegaly than in control subjects (P = 0.01), with pRNFL thickness significantly lower in the temporal superior and temporal inferior quadrants. Contrary to our expectations, pRNFL thickness in the nasal quadrant was similar between acromegalic and control subjects. The mean overall pRNFL thickness and superonasal, nasal, inferonasal, and inferotemporal quadrant pRNFL thicknesses were found to correlate with the mean deviation (MD) according to Spearman's correlation. However, other quadrants were not correlated with VF sensitivity. No significant difference in CMT values was observed (P = 0.6). GCIPL thickness was significantly lower in all quadrants of the inner and outer macula, except for central and inferior outer quadrants, in the acromegaly group than that in the control group (P < 0.05). GCIPL thicknesses of the inferior inner and outer macula quadrants were found to correlate with MD, whereas no correlation was observed between other quadrants and VF sensitivity. We demonstrated that GCIPL thickness decreased in patients with acromegaly compared with that in control subjects. However, the nasal quadrant pRNFL thickness was similar in acromegaly, in contrast to our expectations. SD-OCT may have utility in the assessment of the effects of acromegaly on retinal structures.

The effect of bone marrow-derived mesenchymal stem cells on chemotherapy induced ovarian failure in albino rats

OBJECTIVES

Chemotherapy targets rapidly dividing tissues in the body. It destroys the progenitor cells in gonads resulting in premature ovarian failure. Studies have suggested that bone marrow-derived stem cells can generate oocytes in chemotherapy treated female rats after transplantation. The present study aimed to assess mechanism of homing, the action of injected BM-MSCs on ovarian function after ovarian damage.

EXPERIMENTAL DESIGN

Seventy two female albino rats were randomly allocated into Control and CTX group, The Experimental protocol was lasted for 12 weeks during which serum FSH and E2 were monitored twice at the end of the 2nd week (12 rats) and 8th week (6 rats). Stem cells identification and homing were evaluated by Flowcytometry and tagging of stem cells with iron oxide particles respectively. Also, histopathological examination was done to evaluate both degeneration (6 rats at 4th week) and regeneration (6 rats at 12th week) of ovarian tissue together with assessment of the levels of TNF-α in ovarian homogenate and IGF-I as a growth factor in ovarian tissue.

PRINCIPAL OBSERVATIONS

Partial improvement of E2 and FSH levels as well as ovarian architecture. Elevation of ovarian TNF- α levels and of IGF-I immunohistochemical expressions in ovarian tissues of BM-MSCs injected rats were noticed following homing of BM- MSCs in the ovarian stroma in both control and chemotherapy groups.

CONCLUSION

Injected BM- MSCs can home in the stroma of the injured ovaries. IGF-I and TNF- α may have a role in the attraction of stem cells in vivo.

Elevated Serum Insulin-Like Growth Factor 1 Levels in Patients with Neurological Remission after Traumatic Spinal Cord Injury

After traumatic spinal cord injury, an acute phase triggered by trauma is followed by a subacute phase involving inflammatory processes. We previously demonstrated that peripheral serum cytokine expression changes depend on neurological outcome after spinal cord injury. In a subsequent intermediate phase, repair and remodeling takes place under the mediation of growth factors such as Insulin-like Growth Factor 1 (IGF-1). IGF-1 is a promising growth factor which is thought to act as a neuroprotective agent. Since previous findings were taken from animal studies, our aim was to investigate this hypothesis in humans based on peripheral blood serum. Forty-five patients after traumatic spinal cord injury were investigated over a period of three months after trauma. Blood samples were taken according to a fixed schema and IGF-1 levels were determined. Clinical data including AIS scores at admission to the hospital and at discharge were collected and compared with IGF-1 levels. In our study, we could observe distinct patterns in the expression of IGF-1 in peripheral blood serum after traumatic spinal cord injury regardless of the degree of plegia. All patients showed a marked increase of levels seven days after injury. IGF-1 serum levels were significantly different from initial measurements at four and nine hours and seven and 14 days after injury, as well as one, two and three months after injury. We did not detect a significant correlation between fracture and the IGF-1 serum level nor between the quantity of operations performed after trauma and the IGF-1 serum level. Patients with clinically documented neurological remission showed consistently higher IGF-1 levels than patients without neurological remission. This data could be the base for the establishment of animal models for further and much needed research in the field of spinal cord injury.

Short-acting insulin analogues versus regular human insulin for adults with type 1 diabetes mellitus

BACKGROUND

Short-acting insulin analogue use for people with diabetes is still controversial, as reflected in many scientific debates.

OBJECTIVES

To assess the effects of short-acting insulin analogues versus regular human insulin in adults with type 1 diabetes.

SEARCH METHODS

We carried out the electronic searches through Ovid simultaneously searching the following databases: Ovid MEDLINE(R), Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid OLDMEDLINE(R) (1946 to 14 April 2015), EMBASE (1988 to 2015, week 15), the Cochrane Central Register of Controlled Trials (CENTRAL; March 2015), ClinicalTrials.gov and the European (EU) Clinical Trials register (both March 2015).

SELECTION CRITERIA

We included all randomised controlled trials with an intervention duration of at least 24 weeks that compared short-acting insulin analogues with regular human insulins in the treatment of adults with type 1 diabetes who were not pregnant.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trials for risk of bias, and resolved differences by consensus. We graded overall study quality using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) instrument. We used random-effects models for the main analyses and presented the results as odds ratios (OR) with 95% confidence intervals (CI) for dichotomous outcomes.

MAIN RESULTS

We identified nine trials that fulfilled the inclusion criteria including 2693 participants. The duration of interventions ranged from 24 to 52 weeks with a mean of about 37 weeks. The participants showed some diversity, mainly with regard to diabetes duration and inclusion/exclusion criteria. The majority of the trials were carried out in the 1990s and participants were recruited from Europe, North America, Africa and Asia. None of the trials was carried out in a blinded manner so that the risk of performance bias, especially for subjective outcomes such as hypoglycaemia, was present in all of the trials. Furthermore, several trials showed inconsistencies in the reporting of methods and results.The mean difference (MD) in glycosylated haemoglobin A1c (HbA1c) was -0.15% (95% CI -0.2% to -0.1%; P value < 0.00001; 2608 participants; 9 trials; low quality evidence) in favour of insulin analogues. The comparison of the risk of severe hypoglycaemia between the two treatment groups showed an OR of 0.89 (95% CI 0.71 to 1.12; P value = 0.31; 2459 participants; 7 trials; very low quality evidence). For overall hypoglycaemia, also taking into account mild forms of hypoglycaemia, the data were generally of low quality, but also did not indicate substantial group differences. Regarding nocturnal severe hypoglycaemic episodes, two trials reported statistically significant effects in favour of the insulin analogue, insulin aspart. However, due to inconsistent reporting in publications and trial reports, the validity of the result remains questionable.We also found no clear evidence for a substantial effect of insulin analogues on health-related quality of life. However, there were few results only based on subgroups of the trial populations. None of the trials reported substantial effects regarding weight gain or any other adverse events. No trial was designed to investigate possible long-term effects (such as all-cause mortality, diabetic complications), in particular in people with diabetes related complications.

AUTHORS' CONCLUSIONS

Our analysis suggests only a minor benefit of short-acting insulin analogues on blood glucose control in people with type 1 diabetes. To make conclusions about the effect of short acting insulin analogues on long-term patient-relevant outcomes, long-term efficacy and safety data are needed.

Retinal fibrosis in diabetic retinopathy

In response to injury, reparative processes are triggered to restore the damaged tissue; however, such processes are not always successful in rebuilding the original state. The formation of fibrous connective tissue is known as fibrosis, a hallmark of the reparative process. For fibrosis to be successful, delicately balanced cellular events involving cell proliferation, cell migration, and extracellular matrix (ECM) remodeling must occur in a highly orchestrated manner. While successful repair may result in a fibrous scar, this often restores structural stability and functionality to the injured tissue. However, depending on the functionality of the injured tissue, a fibrotic scar can have a devastating effect. For example, in the retina, fibrotic scarring may compromise vision and ultimately lead to blindness. In this review, we discuss some of the retinal fibrotic complications and highlight mechanisms underlying the development of retinal fibrosis in diabetic retinopathy.

Intravitreal Topotecan Inhibits Laser-induced Choroidal Neovascularization in a Rat Model

Purpose:

A two-phase preclinical study was designed to determine the safe dose of intravitreal topotecan and its inhibitory effect on experimental choroidal neovascularization (CNV) in a rat model.

Methods:

In phase I, 42 rats were categorized into 6 groups, 5 of which received intravitreal topotecan injections of 0.125 μg, 0.25 μg, 0.5 μg, 0.75 μg, and 1.0 μg/5 μl, respectively; the control group received an injection of normal saline. Ophthalmic examination and electroretinography (ERG) were performed on days 7 and 28, and enucleated globes were processed for histopathology and immunostaining for glial fibrillary acidic protein. In phase II, CNV was induced via laser burns in 20 rats and the animals were divided into 2 groups. One group received topotecan and the other received normal saline intravitreally. Four weeks later, mean scores of fluorescein leakage on fluorescein angiography as well as mean CNV areas on histology sections were compared.

Results:

In phase I, clinical, ERG and histopathologic results were unremarkable in terms of retinal toxicity in all groups. Based on the results of phase I, a dose of 1 μg/5 μl topotecan was chosen for phase II. Leakage scores obtained from late-phase fluorescein angiography were significantly lower in topotecan-treated than control eyes (P < 0.01) four weeks after induction of CNV. Compared to control eyes, topotecan-treated eyes showed a significantly lower incidence of fibrovascular proliferation (8.7% vs. 96.2%) and significantly smaller areas of CNV (P < 0.01).

Conclusion:

Intravitreal injection of topotecan at a dose of 1 μg/5 μl is safe and may be a promising treatment for CNV.

Estrogen-IGF-1 interactions in neuroprotection: ischemic stroke as a case study

The steroid hormone 17b-estradiol and the peptide hormone insulin-like growth factor (IGF)-1 independently exert neuroprotective actions in neurologic diseases such as stroke. Only a few studies have directly addressed the interaction between the two hormone systems, however, there is a large literature that indicates potentially greater interactions between the 17b-estradiol and IGF-1 systems. The present review focuses on key issues related to this interaction including IGF-1 and sex differences and common activation of second messenger systems. Using ischemic stroke as a case study, this review also focuses on independent and cooperative actions of estrogen and IGF-1 on neuroprotection, blood brain barrier integrity, angiogenesis, inflammation and post-stroke epilepsy. Finally, the review also focuses on the astrocyte, a key mediator of post stroke repair, as a local source of 17b-estradiol and IGF-1. This review thus highlights areas where significant new research is needed to clarify the interactions between these two neuroprotectants.

Evaluation of central corneal and central retinal thicknesses and intraocular pressure in acromegaly patients

INTRODUCTION

Acromegaly is a disorder with increased morbidity which can involve many organs and the eye can be one of them which was investigated in few reports. Herein, we aimed to evaluate CCT, IOP and retinal thickness (RT), and their relationships with serum GH and IGF-1 levels and disease duration, in acromegaly patients. We compared the ocular parameters with those of a control group. This study included the largest number of patients of any comparable investigation to date.

MATERIAL AND METHOD

We enrolled 30 acromegaly patients (15 male, 15 female and age: 48.4 ± 12.8 years) and 21 age and gender matched controls. All participants underwent complete hormonal and ophtalmological evaluation including central corneal thickness (CCT), retinal thickness (RT) and intraocular pressure (IOP) values.

RESULTS

There were no significant differences in median right and left CCTs and mean CCT (p = 0.646, p = 0.667 and p = 0.384, respectively). Nor were there statistically significant differences in median right and left RT, or mean central RT, between the acromegaly and control groups (p = 0.977, p = 0.738 and p = 0.811, respectively). However median right, left and mean IOPs were found to be significantly higher in the acromegaly group, despite there being no difference in the CCT values (p = 0.011, p = 0.028 and p = 0.047, respectively). When we analyzed two subgroups of acromegaly patients (active/inactive), we found that the median right, left and mean CCTs and RTs, were not significantly different between the groups. Although there was a significant difference in IOP between the acromegaly and control groups, the two subgroups of acromegaly patients had similar IOPs (p = 0.400, p = 0.621 and p = 0.451 for right, left and mean IOPs, respectively). IOP was not found to be correlated with serum IGF-I, GH or disease duration in acromegaly patients.

CONCLUSION

Our study results suggest that acromegaly is associated with increased ocular pressures irrespective of disease activity. Therefore detailed ocular evaluation should be a routine component of the follow up visits of acromegaly patients.

Macrophages in cardiac homeostasis, injury responses and progenitor cell mobilisation

Macrophages are an immune cell type found in every organ of the body. Classically, macrophages are recognised as housekeeping cells involved in the detection of foreign antigens and danger signatures, and the clearance of tissue debris. However, macrophages are increasingly recognised as a highly versatile cell type with a diverse range of functions that are important for tissue homeostasis and injury responses. Recent research findings suggest that macrophages contribute to tissue regeneration and may play a role in the activation and mobilisation of stem cells. This review describes recent advances in our understanding of the role played by macrophages in cardiac tissue maintenance and repair following injury. We examine the involvement of exogenous and resident tissue macrophages in cardiac inflammatory responses and their potential activity in regulating cardiac regeneration.

Importance of insulin resistance to vascular repair and regeneration

Metabolic insulin resistance is apparent across a spectrum of clinical disorders, including obesity and diabetes, and is characterized by an adverse clustering of cardiovascular risk factors related to abnormal cellular responses to insulin. These disorders are becoming increasingly prevalent and represent a major global public health concern because of their association with significant increases in atherosclerosis-related mortality. Endogenous repair mechanisms are thought to retard the development of vascular disease, and a growing evidence base supports the adverse impact of the insulin-resistant phenotype upon indices of vascular repair. Beyond the impact of systemic metabolic changes, emerging data from murine studies also provide support for abnormal insulin signaling at the level of vascular cells in retarding vascular repair. Interrelated pathophysiological factors, including reduced nitric oxide bioavailability, oxidative stress, altered growth factor activity, and abnormal intracellular signaling, are likely to act in conjunction to impede vascular repair while also driving vascular damage. Understanding of these processes is shaping novel therapeutic paradigms that aim to promote vascular repair and regeneration, either by recruiting endogenous mechanisms or by the administration of cell-based therapies.

Quantitative phosphoproteomics analysis reveals broad regulatory role of heparan sulfate on endothelial signaling

Heparan sulfate (HS) is a linear, abundant, highly sulfated polysaccharide that expresses in the vasculature. Recent genetic studies documented that HS critically modulates various endothelial cell functions. However, elucidation of the underlying molecular mechanism has been challenging because of the presence of a large number of HS-binding ligands found in the examined experimental conditions. In this report, we used quantitative phosphoproteomics to examine the global HS-dependent signaling by comparing wild type and HS-deficient endothelial cells that were cultured in a serum-containing medium. A total of 7222 phosphopeptides, corresponding to 1179 proteins, were identified. Functional correlation analysis identified 25 HS-dependent functional networks, and the top five are related to cell morphology, cellular assembly and organization, cellular function and maintenance, cell-to-cell communication, inflammatory response and disorder, cell growth and proliferation, cell movement, and cellular survival and death. This is consistent with cell function studies showing that HS deficiency altered endothelial cell growth and mobility. Mining for the underlying molecular mechanisms further revealed that HS modulates signaling pathways critically related to cell adhesion, migration, and coagulation, including ILK, integrin, actin cytoskeleton organization, tight junction and thrombin signaling. Intriguingly, this analysis unexpectedly determined that the top HS-dependent signaling is the IGF-1 signaling pathway, which has not been known to be modulated by HS. In-depth analysis of growth factor signaling identified 22 HS-dependent growth factor/cytokine/growth hormone signaling pathways, including those both previously known, such as HGF and VEGF, and those unknown, such as IGF-1, erythropoietin, angiopoietin/Tie, IL-17A and growth hormones. Twelve of the identified 22 growth factor/cytokine/growth hormone signaling pathways, including IGF-1 and angiopoietin/Tie signaling, were alternatively confirmed in phospho-receptor tyrosine kinase array analysis. In summary, our SILAC-based quantitative phosphoproteomic analysis confirmed previous findings and also uncovered novel HS-dependent functional networks and signaling, revealing a much broader regulatory role of HS on endothelial signaling.

An abundant tissue macrophage population in the adult murine heart with a distinct alternatively-activated macrophage profile

Cardiac tissue macrophages (cTMs) are a previously uncharacterised cell type that we have identified and characterise here as an abundant GFP(+) population within the adult Cx(3)cr1(GFP/+) knock-in mouse heart. They comprise the predominant myeloid cell population in the myocardium, and are found throughout myocardial interstitial spaces interacting directly with capillary endothelial cells and cardiomyocytes. Flow cytometry-based immunophenotyping shows that cTMs exhibit canonical macrophage markers. Gene expression analysis shows that cTMs (CD45(+)CD11b(+)GFP(+)) are distinct from mononuclear CD45(+)CD11b(+)GFP(+) cells sorted from the spleen and brain of adult Cx(3)cr1(GFP/+) mice. Gene expression profiling reveals that cTMs closely resemble alternatively-activated anti-inflammatory M2 macrophages, expressing a number of M2 markers, including Mrc1, CD163, and Lyve-1. While cTMs perform normal tissue macrophage homeostatic functions, they also exhibit a distinct phenotype, involving secretion of salutary factors (including IGF-1) and immune modulation. In summary, the characterisation of cTMs at the cellular and molecular level defines a potentially important role for these cells in cardiac homeostasis.

Selective inner retinal dysfunction in growth hormone transgenic mice

OBJECTIVE

The discovery of locally produced growth hormone (GH) and its receptor in the retina of rodents raises the possibility that GH might modulate retinal function. To test this hypothesis, we determined the retinal electroretinogram (ERG) of bovine GH (bGH) transgenic mice.

DESIGN

ERGs were recorded from 11 wild type (WT) and 9 bGH mice, at 2 months of age in response to a series of light flashes at increasing intensity. Three ERG components were assessed for their amplitude and timing: a-wave, b-wave and oscillatory potentials (OPs). OPs were isolated with a 75-300 Hz digital filter. Retina layer sizes, nuclei number and vascularization were assessed by respectively staining cross sections with DAPI and Bandeiraea simplicifolia.

RESULTS

OPs were selectively affected in the bGH mouse compared to WT. When OP amplitude values were normalized to the a-wave amplitude (to account for inter-animal variability in WT and bGH groups), OP2, OP3, and OP4 showed amplitude reductions (of 65%, 72%, and 68%, respectively) in the bGH mouse compared to the WT. This was accompanied by a prolongation of the implicit time for the peak of OP3 (28.1 vs 31.1 ms, WT vs bGH) and OP4 (37.8 vs 41.6 ms), while the implicit time of a- and b-waves were unaffected. Fast Fourier transform analysis revealed that the OPs' dominant frequency was significantly reduced (P<0.05) in the bGH mice (100 Hz) compared to WT (108Hz). There was no significant change in retinal histology except for a significant increase in the axial length of the eye in bGH mice.

CONCLUSIONS

Mice expressing bGH display a selective inner retinal defect as demonstrated using ERG recordings. The specific OP defect observed in these mice is similar to the ERG results obtained in patients with diabetic retinopathy and in related animal models.

Microvascular modifications in diabetic retinopathy

Patients struggling with diabetes are at elevated risks for several sight-threatening diseases, including proliferative diabetic retinopathy (DR). DR manifests in two stages: first, the retinal microvasculature is compromised and capillary degeneration occurs; subsequently, an over-compensatory angiogenic response is initiated. Early changes in the retinal microcirculation include disruptions in blood flow, thickening of basement membrane, eventual loss of mural cells, and the genesis of acellular capillaries. Endothelial apoptosis and capillary dropout lead to a hypoxic inner retina, alterations in growth factors, and upregulation of inflammatory mediators. With disease progression, pathologic angiogenesis generates abnormal preretinal microvessels. Current therapies, which include panretinal photocoagulation and vitrectomy, have remained unaltered for several decades. With several exciting preclinical advances, emergent technologies and innovative cellular targets may offer newfound hope for developing "next-generation" interventional or preventive clinical approaches that will significantly advance current standards of care and clinical outcomes.

Novel protective properties of IGFBP-3 result in enhanced pericyte ensheathment, reduced microglial activation, increased microglial apoptosis, and neuronal protection after ischemic retinal injury

This study was conducted to determine the perivascular cell responses to increased endothelial cell expression of insulin-like growth factor binding protein-3 (IGFBP-3) in mouse retina. The contribution of bone marrow cells in the IGFBP-3-mediated response was examined using green fluorescent protein-positive (GFP(+)) adult chimeric mice subjected to laser-induced retinal vessel occlusion injury. Intravitreal injection of an endothelial-specific IGFBP-3-expressing plasmid resulted in increased differentiation of GFP(+) hematopoietic stem cells (HSCs) into pericytes and astrocytes as determined by immunohistochemical analysis. Administration of IGFBP-3 plasmid to mouse pups that underwent the oxygen-induced retinopathy model resulted in increased pericyte ensheathment and reduced pericyte apoptosis in the developing retina. Increased IGFBP-3 expression reduced the number of activated microglial cells and decreased apoptosis of neuronal cells in the oxygen-induced retinopathy model. In summary, IGFBP-3 increased differentiation of GFP(+) HSCs into pericytes and astrocytes while increasing vascular ensheathment of pericytes and decreasing apoptosis of pericytes and retinal neurons. All of these cytoprotective effects exhibited by IGFBP-3 overexpression can result in a more stable retinal vascular bed. Thus, endothelial expression of IGFBP-3 may represent a physiologic response to injury and may represent a therapeutic strategy for the treatment of ischemic vascular eye diseases, such as diabetic retinopathy and retinopathy of prematurity.

GSK-3β/CREB axis mediates IGF-1-induced ECM/adhesion molecule expression, cell cycle progression and monolayer permeability in retinal capillary endothelial cells: Implications for diabetic retinopathy

Various growth factors and cytokines are implicated in endothelial dysfunction and blood-retinal barrier (BRB) breakdown in early diabetic retinopathy (DR). However, cellular and molecular mechanisms that may underlie the pathology of DR are not fully understood yet. We therefore examined the effect of insulin-like growth factor (IGF)-1 on ECM/adhesion molecule expression, cell cycle regulation and monolayer permeability in an endothelial cell line (TR-iBRB2). We investigate whether the action of IGF-1 (1) involves glycogen synthase kinase 3beta (GSK-3β) and cAMP responsive transcription factor (CREB) and (2) alters ECM/adhesion molecule gene expression. Treatment of TR-iBRB2 cell with IGF-1 (100ng/ml for 0-24h) increases phosphorylation of (i) Akt Thr308, and its substrates including GSK-3β at Ser9, which inactivates its kinase function, and (ii) CREB at Ser133 (activation). These phosphorylations correlate positively with enhanced expression of CREB targets such as ECM protein fibronectin and cell cycle progression factor cyclin D1. However, stable transfection of a mutant GSK3β(S9A) or a dominant negative K-CREB in TR-iBRB2 prevents IGF-1-induced fibronectin and cyclin D1 expression. Furthermore, IGF-1 reduces the level of intercellular adherence molecule VE-cadherin and increases monolayer permeability in TR-iBRB2 cells when measured by FITC-dextran leakage. The effect of IGF-1 on VE-cadherin and membrane permeability is absent in TR-iBRB2 cells expressing the GSK-3β(S9A). Similarly, K-CREB reverses IGF-1 down-regulation of VE-cadherin and up-regulation of fibronectin. These results indicate that GSK-3β/CREB axis alters ECM/adhesion molecule expression and cell cycle progression in retinal endothelial cells, and may potentially contribute to endothelial dysfunction and BRB leakage in DR.

Neurotrophic factors improve muscle reinnervation from embryonic neurons

Motoneurons die in diseases like amyotrophic lateral sclerosis and after spinal cord trauma, inducing muscle denervation. We tested whether transplantation of embryonic cells with neurotrophic factors into peripheral nerve of adult rats improves muscle reinnervation and motor unit function more than cells alone. One week after sciatic nerve section, embryonic ventral spinal cord cells were transplanted into the tibial nerve with or without glial cell line-derived neurotrophic factor, hepatocyte growth factor, and insulin-like growth factor-1. These cells represented the only neuron source for muscle reinnervation. Ten weeks after transplantation, all medial gastrocnemius muscles contracted in response to electrical stimulation of cell transplants with factors. Only 80% of muscles responded with cells alone. Factors and cells resulted in survival of more motoneurons and reinnervation of more muscle fibers for a given axon (motor unit) number. Greater reinnervation from embryonic cells may enhance muscle excitation by patterned electrical stimulation.

Angiogenin-mediated ribosomal RNA transcription as a molecular target for treatment of head and neck squamous cell carcinoma

Squamous cell carcinoma of the head and neck (HNSCC) is the eighth most common disease, affecting approximately 640,000 patients worldwide each year. Despite recent advances in surgery, radiotherapy, and chemotherapy, the overall cure for patients with HNSCC has remained at less than 50% for many decades. Patients with recurrent and metastatic disease have a median survival of only 6-10 months. Systemic chemotherapy is the only treatment option for those patients. New treatment options are thus desperately needed to supplement, complement, or replace currently available therapies. New agents that target molecular and cellular pathways of the disease pathogenesis of HNSCC are promising candidates. One class of these new agents is angiogenesis inhibitors that have been proven effective in the treatment of advanced colorectal, breast, and non-small cell lung cancers. Similar to other solid tumors, angiogenesis plays an important role in the pathogenesis of HNSCC. A number of angiogenic factors including vascular endothelial growth factor (VEGF) and angiogenin (ANG) have been shown to be significantly upregulated in HNSCC. Among them, ANG is unique in which it is a ribonuclease that regulates ribosomal RNA (rRNA) transcription. ANG-stimulated rRNA transcription has been shown to be a general requirement for angiogenesis induced by other angiogenic factors. ANG inhibitors have been demonstrated to inhibit angiogenesis and tumor growth induced not only by ANG but also by other angiogenic factors. As the role of ANG in HNSCC is being unveiled, the therapeutic potential of ANG inhibitors in HNSCC is expected.

A randomized, double-masked controlled clinical trial of Sandostatin long-acting release depot in patients with postsurgical cystoid macular edema

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of octreotide, a somatostatin analog, for treatment of postsurgical cystoid macular edema.

METHODS

Twenty-one patients with chronic, refractory postsurgical cystoid macular edema and Early Treatment Diabetic Retinopathy Study best-corrected visual acuity of 20/25 to 20/400 were randomized 2:1 to 30 mg monthly intramuscular octreotide or placebo. Outcome measures were visual acuity (primary) and macular thickness and fluorescein angiographic leakage (secondary).

RESULTS

Fourteen eyes received octreotide and seven eyes received placebo. Mean duration of cystoid macular edema was 2.65 and 1.99 years for Sandostatin long-acting release and placebo groups, respectively. Visual acuity at 6 months improved > or =2 lines in 7 of 14 eyes (50%) in the treatment group and 0 of 7 eyes in the placebo group (P = 0.046). Improvement in retinal thickening and angiographic leakage occurred in 3 of 13 eyes (23.1%) and 3 of 14 eyes (21.4%) of the treatment group, respectively, and in 1 of 7 eyes (14.3%) (P = 1.0 compared with the treatment group) and 0 of 7 eyes in the placebo group (P = 0.52 compared with the treatment group). The three eyes that improved in all parameters were treated with octreotide.

CONCLUSION

Although there were no statistically significant differences between both groups in retinal thickening or angiographic leakage, octreotide-treated patients were more likely to experience a > or =2-line improvement in visual acuity. However, this observation cannot be generalized because of the small sample size.

Regulation of vascular endothelial growth factor (VEGF) splicing from pro-angiogenic to anti-angiogenic isoforms: a novel therapeutic strategy for angiogenesis

Vascular endothelial growth factor (VEGF) is produced either as a pro-angiogenic or anti-angiogenic protein depending upon splice site choice in the terminal, eighth exon. Proximal splice site selection (PSS) in exon 8 generates pro-angiogenic isoforms such as VEGF₁₆₅, and distal splice site selection (DSS) results in anti-angiogenic isoforms such as VEGF₁₆₅b. Cellular decisions on splice site selection depend upon the activity of RNA-binding splice factors, such as ASF/SF2, which have previously been shown to regulate VEGF splice site choice. To determine the mechanism by which the pro-angiogenic splice site choice is mediated, we investigated the effect of inhibition of ASF/SF2 phosphorylation by SR protein kinases (SRPK1/2) on splice site choice in epithelial cells and in in vivo angiogenesis models. Epithelial cells treated with insulin-like growth factor-1 (IGF-1) increased PSS and produced more VEGF₁₆₅ and less VEGF₁₆₅b. This down-regulation of DSS and increased PSS was blocked by protein kinase C inhibition and SRPK1/2 inhibition. IGF-1 treatment resulted in nuclear localization of ASF/SF2, which was blocked by SPRK1/2 inhibition. Pull-down assay and RNA immunoprecipitation using VEGF mRNA sequences identified an 11-nucleotide sequence required for ASF/SF2 binding. Injection of an SRPK1/2 inhibitor reduced angiogenesis in a mouse model of retinal neovascularization, suggesting that regulation of alternative splicing could be a potential therapeutic strategy in angiogenic pathologies.

Inhibition of VEGF secretion and experimental choroidal neovascularization by picropodophyllin (PPP), an inhibitor of the insulin-like growth factor-1 receptor

INTRODUCTION

Choroidal neovascularization (CNV) is a debilitating complication of age-related macular degeneration (AMD) and a leading cause of vision loss. Along with other angiogenic factors like vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF-1) and its receptor, IGF-1R, have been implicated in CNV.

PURPOSE

We have previously shown that the cyclolignan picropodophyllin (PPP) efficiently blocks the insulin-like growth factor-1 receptor (IGF-1R) activity and causes cell death in uveal melanoma cell lines and in an in-vivo model. In this study we investigated the effect of PPP on VEGF expression both in vitro and in vivo and whether this effect has anti-angiogenic consequences in a murine CNV model.

MATERIALS AND METHODS

C57BL/6J mice with laser-induced CNVs were treated with PPP. Effects on CNV area were assayed by image analysis. VEGF levels in choroids and retinal pigment epithelial cells (APRE-19) were measured by Western blot or ELISA. Transcriptional activation of the VEGF promoter was determined by luciferase reporter gene assay.

RESULTS

Mice treated with PPP, administered intraperitoneally or orally, showed 22-32% (p = 0.002) decrease in CNV area. Furthermore, VEGF levels in the choroids were significantly reduced. In cultured APRE-19 cells, IGF-1 was shown to increase VEGF secretion. This increase was completely blocked by PPP. We could confirm that PPP reduced the level of transcriptional activity of VEGF promoter.

CONCLUSIONS

PPP reduces IGF-1 dependent VEGF expression and CNV in vivo. Accordingly, IGF-1R inhibitors may be useful tools in the therapy of conditions associated with CNV including neovascular AMD.

Mecasermin rinfabate: rhIGF-I/rhIGFBP-3 complex: iPLEX

BACKGROUND

Mecasermin rinfabate (iPLEX), comprising rhIGF-I complexed to rhIGFBP-3, was developed in an attempt to prolong the half-life of IGF-I and potentially reduce side effects. It is administered as a once-daily subcutaneous injection. Treatment with rhIGF-I has been explored in a number of growth and endocrine disorders.

OBJECTIVE

To review the published literature regarding the pharmacokinetics, safety profile and clinical efficacy of Mecasermin rinfabate.

METHODS

A comprehensive search via the NCBI PubMed portal was performed using the search terms rhIGF-I/rhIGFBP-3 complex, iPLEX and Somatokine.

RESULTS

The effects of Mecasermin rinfabate have been explored in a number of clinical situations including diabetes, severe insulin resistance, osteopaenia, burns and growth hormone insensitivity syndrome, with outcomes similar to those of rhIGF-I alone.

CONCLUSIONS

The biological effects of Mecasermin rinfabate are largely similar to those previously reported with rhIGF-I. There are little published data pertaining to pharmacokinetic properties in human subjects, and the side effect profile appears similar to that of rhIGF-I alone.

Intracameral Avastin dramatically resolves iris neovascularization and reverses neovascular glaucoma

PURPOSE

To report the biologic effect of intracameral bevacizumab in patients with iris neovascularization secondary to proliferative retinal vasculopathies.

METHODS

Sixteen eyes of 15 patients with iris neovascularization associated with or without neovascular glaucoma secondary to proliferative retinal vasculopathies received intracameral bevacizumab (1.25 mg). Ophthalmic evaluations included Snellen visual acuity (VA), complete ophthalmic iris angiography, and slit lamp photography. Main outcome measure was change in degree of iris neovascularization. Secondary outcomes included fluorescein iris angiographic leakage, control of intraocular pressure, and changes in VA.

RESULTS

All patients with neovascularization demonstrated by slit lamp photography and fluorescein angiography (16/16 eyes) had complete (or at least partial) reduction in leakage of the neovascularization within 3 weeks after the injection. Leakage from iris neovascularization resolved in 12 of 16 (75%) eyes. In two cases recurrent leakage was seen as early as 4 weeks necessitating repeat injection. Intraocular pressure was controlled with maximum medical therapy in eight of nine eyes reducing the need for glaucoma surgery. Visual acuity improved from a median of hand motions to 20/200.

CONCLUSIONS

In summary, intracameral bevacizumab was effective in reversing iris neovascularization in the majority of patients. It also facilitated intraocular pressure control in patients with associated glaucoma.

Insulin-like growth factors, angiopoietin-2, and pigment epithelium-derived growth factor in the hypoxic retina

As the response of the adult retina to hypoxia is likely to differ from that already established in the neonatal animal, this study was undertaken to examine the expression patterns of insulin-like growth factor-I (IGF-I) and -II (IGF-II), angiopoietin-2 (Ang-2), and pigment epithelium-derived growth factor (PEDF) in normal and hypoxic retinas of adult rats. In the latter, the retinas were examined from 3 hr to 14 days after hypoxic exposure. The mRNA and protein expression of IGF-I, IGF-II, Ang-2, and PEDF in the retina was determined by real-time RT-PCR, Western blotting, and immunohistochemistry. The results showed up-regulated expression of IGF-I, IGF-II, and Ang-2 mRNA and protein in response to hypoxia, whereas PEDF expression was drastically reduced, suggesting that increased expression of IGF-I and IGF-II may be involved not only in neovascularization but also in neuroprotection in hypoxic conditions. The up-regulation of Ang-2, a proangiogenic factor, and the down-regulation of PEDF, an antiangiogenic factor, is indicative of an imbalance between pro- and antiangiogenic factors in the hypoxic retina that may favor neovascularization. This was supported by the increased density of rat endothelial cell antigen-1 (RECA-1) protein quantification and RECA-1-stained blood vessels in the inner retina.

Insulin, insulin analogues and diabetic retinopathy

Insulin is absolutely vital for living beings. It is not only involved in metabolism, but also in the regulation of growth factors, e.g. IGF-1. In this review we address the role insulin has in the natural evolution of diabetic retinopathy. On the one hand, chronic deficiency of insulin and IGF-1 at the retina is thought to cause capillary degeneration, with subsequent ischaemia. On the other hand, acute abundance of (exogenously administered) insulin and IGF-1 enhances ischaemia-induced VEGF expression. A critical ratio of tissue VEGF-susceptibility: VEGF-availability triggers vascular proliferation (i.e. of micro-aneurysms and/or abnormal vessels). The patent-protected insulin analogues Lispro, Glulisine, Aspart, Glargine and Detemir are artificial insulin derivatives with altered biological responses compared to natural insulin (e.g. divergent insulin and /or IGF-1 receptor-binding characteristics, signalling patterns, and mitogenicity). Their safety profiles concerning diabetic retinopathy remain to be established by randomised controlled trials. Anecdotal reports and circumstantial evidence suggest that Lispro and Glargine might worsen diabetic retinopathy.

Long-acting insulin analogues versus NPH insulin (human isophane insulin) for type 2 diabetes mellitus

BACKGROUND

Despite indications from epidemiological trials that higher blood glucose concentrations are associated with a higher risk for developing micro- and macrovascular complications, evidence for a beneficial effect of antihyperglycaemic therapy in patients with type 2 diabetes mellitus is conflicting. Two large studies, the United Kingdom Prospective Diabetes Study (UKPDS) and the University Group Diabetes Program (UGDP), did not find a reduction of cardiovascular endpoints through improvement of metabolic control. The theoretical benefits of newer insulin analogues might result in fewer macrovascular and microvascular events.

OBJECTIVES

To assess the effects of long-term treatment with long-acting insulin analogues (insulin glargine and insulin detemir) compared to NPH insulin in patients with type 2 diabetes mellitus.

SEARCH STRATEGY

Studies were obtained from computerised searches of MEDLINE, EMBASE, The Cochrane Library and communication with experts in the field as well as insulin producing companies.

SELECTION CRITERIA

Studies were included if they were randomised controlled trials in adults with diabetes mellitus type 2 and had a trial duration of at least 24 weeks.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Pooling of studies by means of random-effects meta-analyses was performed.

MAIN RESULTS

Six studies comparing insulin glargine to NPH (Neutral Protamine Hagedorn) insulin and two studies comparing insulin detemir to NPH insulin were identified. In these trials, 1715 patients were randomised to insulin glargine and 578 patients to insulin detemir. Duration of the included trials ranged from 24 to 52 weeks. Metabolic control, measured by glycosylated haemoglobin A1c (HbA1c) as a surrogate endpoint, and adverse effects did not differ in a clinical relevant way between treatment groups. While no statistically significant difference for severe hypoglycaemia rates was shown in any of the trials, the rate of symptomatic, overall and nocturnal hypoglycaemia was statistically significantly lower in patients treated with either insulin glargine or detemir. No evidence for a beneficial effect of long-acting analogues on patient-oriented outcomes like mortality, morbidity, quality of life or costs could be obtained.

AUTHORS' CONCLUSIONS

Our analysis suggests, if at all only a minor clinical benefit of treatment with long-acting insulin analogues for patients with diabetes mellitus type 2 treated with "basal" insulin regarding symptomatic nocturnal hypoglycaemic events. Until long-term efficacy and safety data are available, we suggest a cautious approach to therapy with insulin glargine or detemir.

Lack of spontaneous ocular neovascularization and attenuated laser-induced choroidal neovascularization in IGF-I overexpression transgenic mice

Robust IGF-I overexpression induces ocular angiogenesis in mice. To investigate the effect of subtle IGF-I overexpression, we examined the ocular phenotype of IGF-II promoter-driven IGF-I transgenic mice. Despite 2.5-fold elevation of IGF-I mRNA in the retina and 29 and 52% increase of IGF-I protein in the retina and aqueous humor, respectively, no ocular abnormality was observed in these transgenics. This was correlated with unaltered VEGF mRNA levels in the transgenic retina. The transgene was also associated with an attenuated laser-induced choroidal neovascularization. Differential expression levels and pattern of IGF-I gene may underlie the different retinal phenotypes in different transgenic lines.

Ocular neovascularization: Implication of endogenous angiogenic inhibitors and potential therapy

Ocular neovascularization (NV) is the primary cause of blindness in a wide range of ocular diseases, such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). The exact mechanism underlying the pathogenesis of ocular NV is not yet well understood, and as a consequence, there is no satisfactory therapy for ocular NV. In the last 10 years, a number of studies provided increasing evidence demonstrating that the imbalance between angiogenic stimulating factors and angiogenic inhibitors is a major contributor to the angiogenesis induced by various insults, such as hypoxia or ischemia, inflammation and tumor. The angiogenic inhibitors alone or in combination with other existing therapies are, therefore, believed to be promising in the treatment of ocular NV in the near future. This article reviews recent progress in studies on the mechanisms and treatment of ocular NV, focusing on the implication and therapeutic potential of endogenous angiogenic inhibitors in ocular NV.