Erythropoietin and microvascular diabetic complications

High glucose concentration produces a short-term increase in pERK1/2 and p85 proteins, having a direct angiogenetic effect by an action similar to VEGF

AIMS

Excessive glucose serum concentration, endothelial dysfunction and microangiopathy are key features of diabetes mellitus, being both diagnostic parameters and pathogenetic mechanisms. Vascular endothelial growth factor (VEGF) is importantly implicated in the physiology and pathology of blood vessels, including diabetic vascular damage.

METHODS

These factors certainly affect endothelial cells, and to evaluate mechanisms involved, we took advantage of telomerase-immortalized human microvascular endothelial (TIME) cells. TIME cells were exposed to different glucose concentrations and to VEGF treatments. Culture conditions also included the use of basement membrane extract, as an in vitro differentiation model. Cell morphology was then evaluated in the different conditions, and cellular proteins were extracted to analyze specific protein products by Western blot.

RESULTS

High glucose concentrations and VEGF did substantially affect neither morphology nor growth of cultured TIME cells, while both considerably increased differentiation into "capillary-like" structures when cells were cultured on basement membrane extract.

CONCLUSIONS

Under these conditions, high glucose concentration and VEGF also produced a short-term increase in pERK1/2 and p85 proteins, while total and phosphorylated AKT were not affected. These data suggest a direct angiogenetic effect of glucose, affecting intracellular transduction mechanisms with an action similar to that of VEGF. This effect on endothelial cell proliferation and differentiation could be part of pathogenetic mechanisms producing diabetic microvascular alterations.

High hemoglobin is associated with increased in-hospital death in patients with chronic obstructive pulmonary disease and chronic kidney disease: a retrospective multicenter population-based study

BACKGROUND

Chronic kidney disease (CKD) is a common comorbidity of chronic obstructive pulmonary disease (COPD). Although high hemoglobin (Hb) is detrimental to CKD patients, its relationship with poor outcomes in the COPD population has not been reported. This study aimed to investigate the relationship between high Hb and in-hospital mortality and to explore reference Hb intervals in patients with COPD and CKD.

METHODS

This retrospective study was multicenter population-based. A total of 47,209 patients who presented with COPD between January 2012 and December 2016 were included. The average Hb level during hospitalization was used as the Hb level. CKD and advanced CKD were defined as estimated glomerular filtration rates < 60 and < 30 ml/min/1.73 m², respectively. The association between Hb level (measured in 1 g/dL intervals) and in-hospital mortality was analyzed in different multivariable logistic regression models by CKD stratification.

RESULTS

The Hb level was decreased in the CKD subgroup. In the non-CKD group, a higher Hb level was not associated with an increased risk of in-hospital death. However, the Hb level and mortality showed a U-shaped relationship in the CKD group. After adjusting for age and Charlson Comorbidity Index, multivariable regression analysis showed that an Hb level > 17 g/dL was associated with an increased risk of death in the CKD group with an odds ratio (OR) of 2.085 (95% CI, 1.019-4.264). Hb > 14 g/dL was related to an increased risk of death in advanced CKD patients (OR, 4.579 (95% CI, 1.243-16.866)).

CONCLUSIONS

High Hb is associated with an increased risk of in-hospital death in COPD patients with CKD, especially among those with advanced CKD. In this group of patients, attention should be paid to those with high Hb levels.

Pathophysiology of diabetic retinopathy

Diabetes is now regarded as an epidemic, with the population of patients expected to rise to 380 million by 2025. Tragically, this will lead to approximately 4 million people around the world losing their sight from diabetic retinopathy, the leading cause of blindness in patients aged 20 to 74 years. The risk of development and progression of diabetic retinopathy is closely associated with the type and duration of diabetes, blood glucose, blood pressure, and possibly lipids. Although landmark cross-sectional studies have confirmed the strong relationship between chronic hyperglycaemia and the development and progression of diabetic retinopathy, the underlying mechanism of how hyperglycaemia causes retinal microvascular damage remains unclear. Continued research worldwide has focussed on understanding the pathogenic mechanisms with the ultimate goal to prevent DR. The aim of this paper is to introduce the multiple interconnecting biochemical pathways that have been proposed and tested as key contributors in the development of DR, namely, increased polyol pathway, activation of protein kinase C (PKC), increased expression of growth factors such as vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1), haemodynamic changes, accelerated formation of advanced glycation endproducts (AGEs), oxidative stress, activation of the renin-angiotensin-aldosterone system (RAAS), and subclinical inflammation and capillary occlusion. New pharmacological therapies based on some of these underlying pathogenic mechanisms are also discussed.