Ranibizumab Monotherapy or Combined with Laser versus Laser Monotherapy for Diabetic Macular Edema: A Meta-Analysis of Randomized Controlled Trials

Objective

To evaluate the relative efficacy of ranibizumab (RBZ) monotherapy or combined with laser (RBZ + Laser) versus laser monotherapy for the treatment of diabetic macular edema (DME).

Methods

A comprehensive literature search using PUBMED, ClinicalTrials.gov, and the Cochrane Library to identify randomized controlled trials (RCTs) comparing RBZ or RBZ + Laser to laser monotherapy in patients with DME. Efficacy estimates were determined by comparing weighted mean differences (WMD) in the change of best corrected visual acuity (BCVA) and central macular thickness (CMT) from baseline, and the risk ratios (RR) for the proportions of patients with at least 15 letters change from baseline. Safety analysis estimated the RR of cardiac disorders at 6 to 12 months in RBZ therapy vs. laser monotherapy. Statistical analysis was performed using the RevMan 5.1 software.

Results

Seven RCTs were selected for this meta-analysis, including 1749 patients (394 patients in the RBZ group, 642 patients in the RBZ + Laser group, and 713 patients in the laser group). RBZ and RBZ + Laser were superior to laser monotherapy in the mean change of BCVA and CMT from baseline (WMD = 5.65, 95% confidence interval (CI), 4.44–6.87, P<0.00001; WMD  = 5.02, 95% CI, 3.83–6.20, P<0.00001, and WMD  = −57.91, 95% CI, −77.62 to −38.20, P<0.00001; WMD  = −56.63, 95% CI, −104.81 to −8.44, P = 0.02, respectively). The pooled RR comparing the proportions of patients with at least 15 letters improvement or deterioration were also in favor of RBZ and RBZ + Laser (RR = 2.94, 95% CI, 1.82–4.77, P<0.00001; RR = 2.04, 95% CI, 1.50–2.78, P<0.00001, and RR = 0.21, 95% CI, 0.06–0.71, P = 0.01; RR = 0.52, 95% CI, 0.29–0.95, P = 0.03, respectively). There were no significant differences between RBZ and RBZ + Laser for any of the parameters. There were no difference in the safety profile between RBZ and laser.

Conclusion

RBZ and RBZ + Laser had better visual and anatomic outcomes than laser monotherapy in the treatment of DME. RBZ + Laser seemed to be equivalent to RBZ.     

Adipocyte protein S3-12 coats nascent lipid droplets

Most animals store lipid intracellularly in protein-coated droplets. The protein coat usually contains at least one member of the PAT (perilipin, adipose differentiation-related protein, and TIP47) family. Evidence suggests that PAT proteins control access to the lipid they enclose. The protein S3-12, which has sequence similarity to the PAT proteins, was found in a screen for adipocyte-specific proteins. The adipocyte expression of S3-12 and its similarity to the PAT proteins suggest that S3-12 is involved in adipocyte lipid storage. To test this hypothesis, we supplemented 3T3-L1 adipocytes with fatty acids and assessed the distribution of S3-12 by immunofluorescence microscopy. Prior to fatty acid incubation, S3-12 was distributed diffusely throughout the cytoplasm on punctate structures of heterogeneous size. After 10 min of lipid loading, S3-12 localized to 500-nm structures concentrated at the adipocyte periphery. After longer incubations, S3-12 coated the surface of lipid droplets up to several micrometers in diameter. Initially, these droplets were distinct from those droplets surrounded by perilipin; but by 240 min, most perilipin-coated droplets had some S3-12 on the surface as well. We additionally report that the formation of S3-12-coated droplets 1) required glucose and fatty acids that can be incorporated into triacylglycerol, 2) was blocked by an inhibitor of triacylglycerol synthesis, and 3) was insulin-dependent. This study reports for the first time the early morphological events in the genesis and maturation of adipocyte lipid droplets.     

Exenatide improves glucose homeostasis and prolongs survival in a murine model of dilated cardiomyopathy

Background

There is growing awareness of secondary insulin resistance and alterations in myocardial glucose utilization in congestive heart failure. Whether therapies that directly target these changes would be beneficial is unclear. We previously demonstrated that acute blockade of the insulin responsive facilitative glucose transporter GLUT4 precipitates acute decompensated heart failure in mice with advanced dilated cardiomyopathy. Our current objective was to determine whether pharmacologic enhancement of insulin sensitivity and myocardial glucose uptake preserves cardiac function and survival in the setting of primary heart failure.

Methodology/Principal Findings

The GLP-1 agonist exenatide was administered twice daily to a murine model of dilated cardiomyopathy (TG9) starting at 56 days of life. TG9 mice develop congestive heart failure and secondary insulin resistance in a highly predictable manner with death by 12 weeks of age. Glucose homeostasis was assessed by measuring glucose tolerance at 8 and 10 weeks and tissue 2-deoxyglucose uptake at 75 days. Exenatide treatment improved glucose tolerance, myocardial GLUT4 expression and 2-deoxyglucose uptake, cardiac contractility, and survival over control vehicle-treated TG9 mice. Phosphorylation of AMP kinase and AKT was also increased in exenatide-treated animals. Total myocardial GLUT1 levels were not different between groups. Exenatide also abrogated the detrimental effect of the GLUT4 antagonist ritonavir on survival in TG9 mice.

Conclusion/Significance

In heart failure secondary insulin resistance is maladaptive and myocardial glucose uptake is suboptimal. An incretin-based therapy, which addresses these changes, appears beneficial.