Indomethacin but not metoprolol reduces exercise-induced albumin excretion rate in type 1 diabetic patients with microalbuminuria

Inflammation in diabetes complications: molecular mechanisms and therapeutic interventions

At present, diabetes mellitus (DM) has been one of the most endangering healthy diseases. Current therapies contain controlling high blood sugar, reducing risk factors like obesity, hypertension, and so on; however, DM patients inevitably and eventually progress into different types of diabetes complications, resulting in poor quality of life. Unfortunately, the clear etiology and pathogenesis of diabetes complications have not been elucidated owing to intricate whole-body systems. The immune system was responsible to regulate homeostasis by triggering or resolving inflammatory response, indicating it may be necessary to diabetes complications. In fact, previous studies have been shown inflammation plays multifunctional roles in the pathogenesis of diabetes complications and is attracting attention to be the meaningful therapeutic strategy. To this end, this review systematically concluded the current studies over the relationships of susceptible diabetes complications (e.g., diabetic cardiomyopathy, diabetic retinopathy, diabetic peripheral neuropathy, and diabetic nephropathy) and inflammation, ranging from immune cell response, cytokines interaction to pathomechanism of organ injury. Besides, we also summarized various therapeutic strategies to improve diabetes complications by target inflammation from special remedies to conventional lifestyle changes. This review will offer a panoramic insight into the mechanisms of diabetes complications from an inflammatory perspective and also discuss contemporary clinical interventions.

Effects of a selective bradykinin B1 receptor antagonist on increased plasma extravasation in streptozotocin-induced diabetic rats: Distinct vasculopathic profile of major key organs

Diffuse vasculopathy is a common feature of the morbidity and increased mortality associated with insulino-dependent type 1 diabetes. Increased vascular permeability leading to plasma extravasation occurs in surrounding tissues following endothelial dysfunction. Such micro- and macro-vascular complications develop over time and lead to oedema, hypertension, cardiomyopathy, renal failure (nephropathy) and other complications (neuropathy, retinopathy). In the present investigation, we studied the effect of a selective bradykinin B(1) receptor antagonist, R-954, on the enhanced vascular permeability in streptozotocin (STZ)-induced diabetic Wistar rats compared with age-matched controls. Plasma extravasation was determined using Evans blue dye in selected target tissues (left and right heart atria, ventricles, lung, abdominal and thoracic aortas, liver, spleen, renal cortex and medulla), at 1 and 4 weeks following STZ administration. The vascular permeability was significantly increased in the aortas, cortex, medulla, and spleen in 1-week STZ rats and remained elevated at 4 weeks of diabetes. Both atria showed an increased vascular permeability only after 4-week STZ-administration. R-954 (2 mg/kg, bolus, s.c.), given 2 h prior to Evans blue dye, to 1- and 4-week diabetic rats significantly inhibited (by 48-100%) plasma leakage in most tested tissues affected by diabetes with no effect in healthy rats. These results showed that the inducible bradykinin B(1) receptor subtype participates in the modulation of the vascular permeability in diabetic rats and suggest that selective bradykinin B(1) receptor antagonism could have a beneficial role in reducing diabetic vascular complications.

Inhibitory effect of a novel bradykinin B1 receptor antagonist, R-954, on enhanced vascular permeability in type 1 diabetic mice

The morbidity and mortality associated with type 1 diabetes are essentially related to the micro- and macrovascular complications that develop over time and lead to several diabetic complications, including hypertension, atherosclerosis, and retinopathy, as well as coronary and renal failure. Normally absent in physiological conditions, the bradykinin B1 receptor (BKB1-R) was recently found to be overexpressed in pathological conditions, including type 1 diabetes. In the present study, we evaluated the effect of the new BKB1-R antagonist, R-954 (Ac-Orn-[Oic2, alpha-MePhe5, D-betaNal7, Ile8]desArg9-bradykinin, on the increase in vascular permeability in streptozotocin (STZ)-diabetic mice. The capillary permeability to albumin was measured by quantifying the extravasation of albumin-bound Evans blue dye in selected target tissues (liver, pancreas, duodenum, ileum, spleen, heart, kidney, stomach, skin, muscle, and thyroid gland). Acute single administration of R-954 (300 microg/kg, i.v.) to type 1 diabetic mice 4 weeks after STZ significantly inhibited the enhanced vascular permeability in most tissues. These data provide further experimental evidence for the implication of BKB1-R in the enhanced vascular permeability associated with type 1 diabetes.

Lisinopril reduces postexercise albuminuria more effectively than atenolol in primary hypertension

Physical exercise causes transient albuminuria. The mechanisms of postexercise albuminuria are not fully clarified but stimulation of the reninangiotensin system (RAS) probably plays a major role through intrarenal haemodynamic changes causing an elevated filtration pressure. In a randomised, double-blind, crossover study we compared the effects on urinary albumin excretion (UAE) of lisinopril (L) and atenolol (A) therapy, i.e. we aimed to investigate whether inhibition of the RAS or inhibition of beta1-adrenoceptor-mediated effects of the sympathetic nervous system differed with regard to changes in UAE. Sixteen patients with uncomplicated primary hypertension were studied. Four standardised bicycle ergometer exercise tests were performed, before and after each active treatment period. UAE 30 min postexercise, determined by radioimmunoassay, was significantly lowered by both treatments: -278 mu g center dot min-1 (L) and -199 mu g center dot min-1 (A). The reduction of postexercise UAE achieved by treatment with the angiotensin-converting enzyme (ACE) inhibitor (L) was significantly greater than that achieved by the beta1-selective adrenoceptor blocker treatment. Blood pressure (BP) at rest and during exercise were equally reduced by both drugs. In conclusion, this study showed that antihypertensive treatment with an ACE inhibitor was more effective in reducing exercise-induced albuminuria than a beta1-selective adrenoceptor-blocking agent with a similar degree of BP reduction in patients with uncomplicated primary hypertension. This suggests that the RAS plays a major role in postexercise albuminuria in hypertensive subjects. The clinical significance of this finding, however, remains to be clarified.

Current therapeutic management of diabetic nephropathy

Roughly 40% of all patients with insulin-dependent diabetes mellitus (IDDM) develop diabetic nephropathy with proteinuria, hypertension and a decrease in glomerular filtration rate 10 to 20 years after the onset of the disease, and 5 years later most patients suffer from end-stage renal disease. Microalbuminuria, defined as an urinary albumin excretion rate (UAER) between 30 and 300 mg/day, strongly predicts the development of nephropathy in IDDM. Nearly all patients with IDDM, a decreasing glomerular filtration rate and a UAER > 300 mg/day have coexisting hypertensive disease additionally worsening renal function. We review the results of recent long-term studies of the current therapeutic management in diabetic patients by means of better blood pressure control, low-protein diet and near-normal blood glucose control in the early microalbuminuric phase as well as in the later phases of the disease characterized by diabetic nephropathy with a UAER > 300 mg/day. Since the large majority of studies have been performed on IDDM, our conclusions with regard to therapy are only valid in this subgroup of diabetic patients.