Kidney development and the fetal programming of adult disease

Prenatal exposure to high level of glucocorticoids increases the susceptibility of renal proximal tubular cells to apoptosis induced by uropathogenic Escherichia coli toxins

Prenatal exposure to excessive glucocorticoids may alter the developing fetus inducing metabolic and endocrine imbalance in various organs, including the kidney. This study aimed at evaluating whether prenatal exposure to high levels of glucocorticoids adversely affects renal cell survival and predisposes to renal cell death. Pregnant rats were injected with 0.1 mg/kg dexamethasone (DEX) i.p. from day 1 of gestation. Renal proximal tubular cells (PTCs) were prepared from 20-day-old offspring in the DEX (DEX cells) and control groups (CON cells). After 4 days' culture, cells were exposed to uropathogenic Escherichia coli ARD6 toxins at concentrations known to induce apoptotic cell death. We found that cell death rate was significantly higher in DEX than in CON cells. Cells exhibited morphological and biochemical features of apoptosis. Conversely, the activity of the antioxidant enzyme catalase was significantly increased in renal cortex homogenate from 20-day-old DEX rats. The antioxidant vitamin E did not prevent apoptosis. These results indicate that prenatal exposure to high levels of glucocorticoids induces alterations in renal PTCs rendering them more sensitive to E. coli toxins via nonoxidative stress. With the increasing use of multiple doses of glucocorticoids in preterm infants, the possibility that antenatal glucocorticoids may lead to renal adverse consequences is of clinical relevance.

Progression of renal disease: new insights into risk factors and pathomechanisms

PURPOSE OF REVIEW

Progression of renal failure, irrespective of the primary cause, is characterized by modification of renal structure, which culminates in terminal renal insufficiency. Interfering with progression continues to be a major challenge and is at the forefront of renal research. This review focuses on recent progress in the understanding of the mechanisms of progression and efforts to interfere with this process.

RECENT FINDINGS

In addition to the long-known risk factors (hypertension and inadequate activation of the renin-angiotensin system), several novel risk factors and pathomechanisms, such as obesity, hyperglycemia, smoking, and several hormones, have recently been identified and investigated. Furthermore, the specific and blood pressure-independent pathogenetic roles of the sympathetic nervous system and the endothelin system in progression have been further clarified. Finally, novel animal models and techniques for studying specific aspects of progression have been developed and introduced.

SUMMARY

Recently, considerable progress has been made concerning novel risk factors, understanding the underlying pathomechanisms, and interfering with the course of progression of renal diseases. Such improved insights will undoubtedly lead to new strategies in the future.

Reduced uteroplacental blood flow alters renal arterial reactivity and glomerular properties in the rat offspring

Fetal malnutrition and hypoxia may modify organ system maturation and result in cardiovascular diseases in the adult. We tested whether intrauterine stress (IUS) leads to persistent alterations of renal biology. In rats, intrauterine stress was induced by ligation of the uterine arteries at day 17 of pregnancy. Renal arteries of the 21-day-old male offspring were isolated to study pharmacological reactivity. Kidneys were dissected to analyze renal structure and beta-adrenoceptor expression. At 21 days of age, half of the animals underwent unilateral left nephrectomy. At the age of 12 weeks, rats were instrumented for blood pressure monitoring, blood sampling, and renal function measurements. After IUS, litter size and birth weight were reduced, whereas the hematocrit was increased. Renal arterial responses to beta-adrenergic stimulation and sensitivity to adenylyl cyclase activation were increased, along with the renal expression of beta2-adrenoceptors. At 21 days and at 6 months of age, the number and density of the glomeruli were reduced, whereas their size was increased. The filtration fraction and urinary albumin concentration were increased 12 weeks after intrauterine stress. In control rats, removal of the left kidney at 21 days of age did not affect kidney function and blood pressure. However, after IUS, the remaining right kidney failed to compensate for the loss of the left kidney, and blood pressure was increased. In conclusion, prenatal stress transiently modifies renal arterial reactivity and results in long-lasting adverse effects on renal structure and function and on renal compensatory mechanisms.

Branching morphogenesis and kidney disease

Branching morphogenesis in the kidney is a tightly regulated, complex process and its disruption potentially can lead to a broad spectrum of diseases, ranging from rare hereditary syndromes to common conditions such as hypertension and chronic kidney failure. This review synthesizes data on branching during kidney development derived from in vitro and in vivo rodent studies and to apply them to human diseases. It discusses how the broad organization of molecular interactions during kidney development might provide a mechanistic framework for understanding disorders related to aberrant branching.