Correlation Between Retinal Microstructure Detected by Optical Coherence Tomography and Best Corrected Visual Acuity in Diabetic Retinopathy Macular Edema

Mesenchymal Stem Cells Regulate Microglial Polarization via Inhibition of the HMGB1/TLR4 Signaling Pathway in Diabetic Retinopathy

Diabetic retinopathy (DR) is recognized as the most prevalent retinal degenerative disorder. Inflammatory response usually precedes microvascular alteration and is the primary factor of diabetic retinopathy. Activated microglia express many pro-inflammatory cytokines that exacerbate retina inflammation and disruption. In the present study, we found that MSCs alleviated blood-retina barrier (BRB) breakdown in diabetic rats, as evidenced by reduced retinal edema, decreased vascular leakage, and increased occludin expression. The MSC-treated retinal microglia exhibited reduced expression of M1-phenotype markers in the diabetic rats, including inducible nitric oxide synthase (iNOS), CD16, and pro-inflammatory cytokines. On the other hand, MSCs increased the expression of M2-phenotype markers, such as arginase-1 (Arg-1), CD206, and anti-inflammatory cytokines. HMGB1/TLR4 signaling pathway is activated in DR and inhibited after MSC treatment. Consistent with in vivo evidence, MSCs drove BV2 microglia toward M2 phenotype in vitro. Overexpression of HMGB1 in microglia reversed the effects of MSC treatment, suggesting HMGB1/TLR4 pathway is necessary for MSCs' regulatory effects on microglia polarization. Collectively, MSCs exert beneficial effects on DR by polarizing microglia from M1 toward M2 phenotype via inhibiting the HMGB1/TLR4 signaling pathway.

Clinically significant macular edema in an underserved population: Association with demographic factors and hemoglobin A1c

SIGNIFICANCE

Suspected clinically significant macular edema (SCSME) from exudates differed among ethnic groups in our underserved population. African American and Asian subjects had higher prevalence than Hispanics and non-Hispanic Caucasians, from the same clinics. Men had higher prevalence than women. Highly elevated blood glucose was frequent and associated with SCSME.

PURPOSE

We investigated the association between the presence of SCSME from exudates and hemoglobin A1c (HbA1c), as well as demographic factors such as age, sex, and ethnic group. Our population was underserved diabetic patients from the same geographic locations. Ethnic groups were White Hispanic, non-Hispanic Caucasian, African American, and Asian, with a high proportion of underrepresented minorities.

METHODS

In a diabetic retinopathy screening study at four community clinics in Alameda County, California, nonmydriatic 45° color fundus images were collected from underserved diabetic subjects following the EyePACS imaging protocol. Images were analyzed for SCSME from exudates by two certified graders. Logistic regression assessed the association between SCSME from exudates and age, sex, ethnic group, and HbA1c.

RESULTS

Of 1997 subjects, 147 (7.36%) had SCSME from exudates. The mean ± standard deviation age was 53.4 ± 10.5 years. The mean ± standard deviation HbA1c level was 8.26 ± 2.04. Logistic regression analysis indicated a significant association between presence of SCSME from exudates and HbA1c levels (p<0.001), sex (p=0.027), and ethnicity (p=0.030). African Americans (odds ratio [OR], 1.63; 95% confidence interval [CI], 1.06 to 2.50; p=0.025) and Asians (OR, 1.63; 95% CI, 1.05 to 2.54; p=0.029) had a higher risk than Hispanics. After adjusting for ethnicity, sex, and age, the odds of developing SCSME from exudates increased by 26.5% with every 1% increase in HbA1c level (OR, 1.26; 95% CI, 1.18 to 1.36; p<0.001).

CONCLUSIONS

In our underserved population, many diabetic patients had very high HbA1c values. Ethnic background (African American > Asians > Hispanics), sex (male > female), and HbA1c level were strong indicators for identifying who is at increased risk of developing SCSME from exudates.

Evaluation of the Relationship Between Diabetic Macular Edema and Renal Function in a Latino Population

INTRODUCTION

Diabetic macular edema (DME) is one of the leading causes of vision impairment. The relationship between DME and estimated glomerular filtration rate (eGFR) has not been clearly evaluated in Hispanic or Latino populations. The objective of this study was to evaluate the eGFR in a Latino population with DME.

METHODS

A cross-sectional, observational, and descriptive study was carried out on the basis of a multicenter phase III clinical trial.

RESULTS

A total of 82 subjects diagnosed with DME (36 women and 46 men) were included in the study. The mean age was 61.93 ± 6.71 years. Mean values of the blood chemistry parameters glycated hemoglobin and eGFR were 7.20 ± 0.95% and 74.42 ± 26.82 mL/min/1.73 m2, respectively. The time elapsed since diagnosis of diabetes mellitus was 15.30 ± 7.35 years, while the duration of DME was 1.41 ± 1.75 years. Mean values for central macular thickness (CMT) and total macular volume (TMV) were 440.99 ± 132.22 µm and 11.97 ± 2.11 mm3, respectively. DME duration had a negative correlation with TMV (Rho - 0.26, p < 0.05) and a positive correlation with mean arterial pressure (Rho 0.26, p < 0.05). CMT was correlated with TMV (Rho 0.43, p < 0.0001) and visual acuity (Rho 0.26, p < 0.05). No significant correlations were observed between eGFR and CMT, TMV, or any demographic variable (p > 0.05). Chronic kidney disease (CKD) was associated with hypertension (OR 9.32, p = 0.035), elevated intraocular pressure (IOP) (OR 0.03, p = 0.011), and advanced age (OR 0.45, p = 0.011). CMT was significantly associated with TMV (β = 27.69, p < 0.0001).

CONCLUSIONS

We did not find a correlation between eGFR and DME. Our findings suggest that the presence of hypertension is associated with a decrease in the GFR < 60 mL/min/1.73 m2, and CKD may be associated with advanced age and elevated IOP which may increase the risk for the development of glaucoma.

TRIAL REGISTRATION

NCT05217680 (clinicaltrials.gov).