Nitric oxide, enhanced by macrophage-colony stimulating factor, mediates renal damage in reflux nephropathy

Toxic essential oils, part VI: Acute oral toxicity of lemon balm (Melissa officinalis L.) essential oil in BALB/c mice

Despite being renowned for its volatiles, the data on the toxicity of the essential oil of lemon balm (Melissa officinalis L., Lamiaceae) is rather limited compared to its solvent/water-soluble extractibles. In this study, the aerial parts essential oil of M. officinalis, with over 130 constituents identified herein, 26 of which detected for the first time, was investigated for acute oral toxicity in BALB/c mice. The oil, composed of predominantly monoterpene aldehydes, citronellal (21.2-21.8%), neral (17.8-18.4%), and geranial (22.9-23.5%), which were assayed in parallel with the oil in some tests, induced significant changes in animal behavior, as well as altered biochemical parameters reflecting liver and kidney functions. Different pathological changes in the stomach, duodenum, liver, and kidneys were detected when the oil was administered in doses higher than 1 g kg^-1. A depletion in the liver/kidney antioxidant capacities and an increased rate of lipid peroxidation was noted for animals treated with lemon balm oil. The calculated value of the oral LD₅₀ in BALB/c mice (2.57 g kg^-1) infers that the essential oil is only moderately toxic.

The Encapsulation of Lycopene in Nanoliposomes Enhances Its Protective Potential in Methotrexate-Induced Kidney Injury Model

Methotrexate is an antimetabolic drug with a myriad of serious side effects including nephrotoxicity, which presumably occurs due to oxidative tissue damage. Here, we evaluated the potential protective effect of lycopene, a potent antioxidant carotenoid, given in two different pharmaceutical forms in methotrexate-induced kidney damage in rats. Serum biochemical (urea and creatinine) and tissue oxidative damage markers and histopathological kidney changes were evaluated after systemic administration of both lycopene dissolved in corn oil and lycopene encapsulated in nanoliposomes. Similar to previous studies, single dose of methotrexate induced severe functional and morphological alterations of kidneys with cell desquamation, tubular vacuolation, and focal necrosis, which were followed by serum urea and creatinine increase and disturbances of tissue antioxidant status. Application of both forms of lycopene concomitantly with methotrexate ameliorated changes in serum urea and creatinine and oxidative damage markers and markedly reversed structural changes of kidney tissue. Moreover, animals that received lycopene in nanoliposome-encapsulated form showed higher degree of recovery than those treated with free lycopene form. The findings of this study indicate that treatment with nanoliposome-encapsulated lycopene comparing to lycopene in standard vehicle has an advantage as it more efficiently reduces methotrexate-induced kidney dysfunction.

The role of nitric oxide on matrix metalloproteinase 2 (MMP2) and MMP9 in placenta and fetus from diabetic rats

Matrix metalloproteinases (MMPs) play an important role in tissue remodeling that accompanies the rapid growth, differentiation, and structural changes of the placenta and several fetal organs. In the present study, we investigated whether the diabetic maternal environment may alter the regulatory homeostasis exerted by nitric oxide (NO) on MMPs activity in the feto-placental unit from rats at midgestation. We found that NADPH-diaphorase activity, which reflects the distribution and activity of NO synthases (NOS), was increased in both placenta and fetuses from diabetic rats when compared with controls. In addition, while a NO donor enhanced MMP2 and MMP9 activities, a NOS inhibitor reduced these activities in the maternal side of the placenta from control rats. This regulatory effect of NO was only observed on MMP9 in the diabetic group. On the other hand, the NO donor did not modify MMP2 and MMP9 activities, while the NOS inhibitor reduced MMP9 activity in the fetal side of both control and diabetic placentas. In the fetuses, MMP2 was enhanced by the NO donor and reduced by the NO inhibitor in both fetuses from control and diabetic rats. Overall, this study demonstrates that NO is able to modulate the activation of MMPs in the feto-placental unit, and provides supportive evidence that increased NOS activity leads to NO overproduction in the feto-placental unit from diabetic rats, an alteration closely related to the observed MMPs dysregulation that may have profound implications in the formation and function of the placenta and the fetal organs.

Lack of endothelial nitric-oxide synthase leads to progressive focal renal injury

Because endothelial nitric-oxide synthase (eNOS) is generally considered protective against renal injury, we examined eNOS knockout mice for kidney pathology. In 80% of the adults examined, the renal surface was marked by distinct indented scars containing crowded small glomeruli but lacking attached tubules. Although vasculature was intact in the scars, Bowman's space was dilated and glomerular tufts were degenerated. The atubular glomeruli were embedded in a dense interstitial matrix composed of cells positive for fibroblast (FSP-1) or macrophage (F4/80) markers, degenerated proximal tubules and collecting ducts, and diffuse fibrotic deposits. Surrounding regions of kidney contained mostly normal-appearing tubules, but enlarged or sclerotic glomeruli were also present. In neonatal animals, apoptosis and necrosis were concentrated in tubules within focal parenchymal zones, with narrowing of the glomerulotubular "neck." In summary, targeted deletion of eNOS in mice leads to progressive focal renal abnormalities, including glomerular hypoplasia, and tubular cell death, leading to separation of glomeruli from tubules and tubular disruption. These abnormalities begin developing during the normal up-regulation of eNOS in the maturing kidney and are similar to those of a variety of chronic renal disorders. Endogenous renal eNOS production therefore seems critical for the maintenance of nephron maturation and integrity.

Macrophage Colony-Stimulating Factor Aggravates Rather than Regenerates Emphysematous Lungs in Mice

BACKGROUND

Lung regeneration is an innovative strategy that may cure pulmonary emphysema. The bone marrow (BM) harbors pulmonary stem cells. Hematopoietic cytokine-driven mobilization of BM cells may thus support lung regeneration.

OBJECTIVES

The aim of this study was to determine whether systemic administration of macrophage colony-stimulating factor (M-CSF) leads to the regeneration of lungs in a murine model of elastase-induced emphysema.

METHODS

C57BL/6J mice were administered elastase intratracheally. Four weeks later, in the absence or presence of elastase treatment, mice were intraperitoneally given either M-CSF or saline on days 1-5 each week for 3 weeks. Lung tissue was harvested 24 h after the last injection.

RESULTS

M-CSF administration without prior elastase did not affect the mean linear intercept, surface area, or surface area/lung volume. In contrast, M-CSF administration following elastase injury caused a greater increase in the mean linear intercept and greater decreases in surface area and surface area/lung volume than saline administration following elastase, indicating that M-CSF aggravated emphysema. This aggravation of emphysema was accompanied by accumulation of pulmonary alveolar macrophages (AMs) expressing metalloproteinase (MMP)-9 and MMP-12. M-CSF stimulated AMs to express MMPs in vitro.

CONCLUSIONS

These results suggest that M-CSF administration does not support lung regeneration but rather aggravates the lung destruction associated with elastase injury.

TUMOR NECROSIS FACTOR-α GENE POLYMORPHISM IN REFLUX NEPHROPATHY

PURPOSE

Interstitial scarring contributes to the progression of renal failure in reflux nephropathy. The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) has been implicated in the disease susceptibility and pathogenesis of several inflammatory diseases promoting interstitial infiltration of inflammatory cells. We evaluate the frequency of TNF-alpha gene polymorphism in patients with reflux nephropathy.

MATERIAL AND METHODS

Renal scarring was evaluated with technetium dimercapto-succinic acid renal scan. Genotyping was performed on 104 patients with reflux nephropathy and 30 controls for the TNF-alpha gene polymorphisms using polymerase chain reaction and restriction digest. This polymorphism involved a guanidine to adenosine transition at position -308 and was designated as TNF1 (-308G) and TNF2 (-308A).

RESULTS

The allele frequencies of TNF1 and TNF2 were 18.8% and 81.2% in patients with reflux nephropathy and 76.7% and 23.3% in controls, respectively. The genotype distribution of TNF-alpha-AA was significantly higher (66.4% vs 10%, p <0.05), while the TNF-alpha-GG was lower (13.4% vs 60%, p <0.05) in patients with reflux nephropathy compared to controls.

CONCLUSIONS

This study demonstrates for the first time the association of the cytokine TNF-alpha gene polymorphism in patients with reflux nephropathy. Our data suggest that patients with vesicoureteral reflux and TNF-alpha AA genotype may have increased susceptibility to reflux nephropathy.

Possible involvement of macrophage-colony stimulating factor in the pathogenesis of cardiac dysfunction in hemodialysis patients

In patients with end stage renal disease on hemodialysis (HD), left ventricular (LV) function is frequently impaired. However, the mechanism of the LV dysfunction is totally unknown. It has been suggested that overproduction of nitric oxide induced by inflammatory cytokines may contribute to the LV dysfunction in some diseased states. In this study, we examined whether inflammatory cytokines play a role in the altered LV function in HD patients. The plasma concentrations of 5 major inflammatory cytokines, including interleukin (IL)-1alpha, IL-1beta, IL-6, tumor necrosis factor-alpha, and macrophage-colony stimulating factor (M-CSF) were measured by enzyme immunoassay with horseradish peroxidase in 18 consecutive patients on HD and in 16 control subjects. Then, we examined the relationship between plasma concentrations of M-CSF and LV ejection fraction (EF) on echocardiography. Among the inflammatory cytokines examined, only the plasma concentrations of M-CSF were significantly elevated in patients on HD as compared to the control subjects. There was no significant change in the M-CSF concentrations before and after HD. Furthermore, there was a significant negative correlation between the plasma concentrations of M-CSF and LVEF. These results suggest that elevated levels of plasma M-CSF may exist prior to the development of LV dysfunction observed in HD patients.

Cyclooxygenase-2 Up-Regulation in Reflux Nephropathy

PURPOSE

Reflux nephropathy (RN) is a major cause of end stage renal failure in children and hypertension is a frequent complication. Cyclooxygenase-2 (COX-2) is an enzyme responsible for the prostaglandin synthesis. It has been shown that COX-2 up-regulates renin production leading to renovascular hypertension. We investigate COX-2 expression in the kidneys of children with RN.

MATERIALS AND METHODS

Kidney specimens from 12 patients 2 to 13 years old with severe RN secondary to primary high grade vesicoureteral reflux obtained at the time of nephrectomy and 5 controls were examined. Single labeled immunohistochemistry was performed with 2 COX-2 antibodies using light and confocal microscopy. Quantification of COX-2 was determined by Western blotting analysis. COX-2 gene expression was evaluated by real-time quantitative reverse transcription polymerase chain reaction.

RESULTS

There was a strong COX-2 immunoreactivity in the proximal tubules and tubulointerstitial space in the RN samples compared to controls. Immunoreactive COX-2 protein expression was markedly increased in RN samples compared to controls. Real-time reverse transcription polymerase chain reaction showed a significant increase in COX-2 mRNA expression in the RN samples compared to controls (p <0.05).

CONCLUSIONS

Over expression of COX-2 in reflux nephropathy suggests that COX-2 may be involved in the pathogenesis of tubulointerstitial damage associated with severe reflux nephropathy.