Anemia in Adenine-Induced Chronic Renal Failure and the Influence of Treatment With Gum Acacia Thereon

The effect of gum Arabic supplementation on cathelicidin expression in monocyte derived macrophages in mice

Background

Antimicrobial peptides (AMPs) are important effectors of the innate defense system. Cathelicidins, (CRAMP in mouse/rat, LL-37 in human) is one of the two major classes of AMPs in humans. The upregulation of LL-37 synthesis is a novel non-antibiotic approach to prevent or treat infectious diseases. Butyrate was found to induce Cathelicidin expression. Gum Arabic (GA), an exudate from Acacia senegaltree, is known for its prebiotic effects. Fermentation of GA by colonic bacteria increases serum butyrate concentrations. This study was conducted to investigate if GA supplementation can increase Cathelicidin expression in macrophages.

Methods

The study was an in-vivo experiment in mice. Thirty mice were randomly divided into three groups, ten mice per group. The two intervention groups received GA dissolved in drinking water in two different concentrations (15% w/v and 30% w/v) for 28 days. The third group served as a control. Blood was collected on Day 29 to isolate peripheral blood mononuclear cells (PBMC) which were cultured to obtain monocyte derived macrophages (MDMs). The transcription level of CRAMP was determined in MDMsby qPCR.

Results

We detected a significant increase (p = 0.023) in CRAMP expression in MDMs following 28 days of 15% GA supplementation, compared to the control group, but there was no significant change in the group on 30% GA supplementation (p = 0.055).

Conclusion

GAsupplementation can induce Cathelicidin expression in MDMs and the effect is dose dependent.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03627-9.

The Development of a PBPK Model for Atomoxetine Using Levels in Plasma, Saliva and Brain Extracellular Fluid in Patients with Normal and Deteriorated Kidney Function

BACKGROUND

Atomoxetine is a treatment for attention-deficit hyperactivity disorder. It inhibits Norepinephrine Transporters (NET) in the brain. Renal impairment can reduce hepatic CYP2D6 activity and atomoxetine elimination which may increase its body exposure. Atomoxetine can be secreted in saliva.

OBJECTIVE

The objective of this work was to test the hypothesis that atomoxetine saliva levels (sATX) can be used to predict ATX brain Extracellular Fluid (bECF) levels and their pharmacological effects in healthy subjects and those with End-Stage Renal Disease (ESRD).

METHODS

The pharmacokinetics of atomoxetine after intravenous administration to rats with chemically induced acute and chronic renal impairments were investigated. A physiologically-based pharmacokinetic (PBPK) model was built and verified in rats using previously published measured atomoxetine levels in plasma and brain tissue. The rat PBPK model was then scaled to humans and verified using published measured atomoxetine levels in plasma, saliva, and bECF.

RESULTS

The rat PBPK model predicted the observed reduced atomoxetine clearance due to renal impairment in rats. The PBPK model predicted atomoxetine exposure in human plasma, sATX and bECF. Additionally, it predicted that ATX bECF levels needed to inhibit NET are achieved at 80 mg dose. In ESRD patients, the developed PBPK model predicted that the previously reported 65% increase in plasma exposure in these patients can be associated with a 63% increase in bECF. The PBPK simulations showed that there is a significant correlation between sATX and bECF in human.

CONCLUSION

Saliva levels can be used to predict atomoxetine pharmacological response.

Neurological sequel of chronic kidney disease: From diminished Acetylcholinesterase activity to mitochondrial dysfunctions, oxidative stress and inflammation in mice brain

With increasing prevalence, chronic kidney disease (CKD) has become a global health problem. Due to the retention of uremic toxins, electrolytes and water, and the resultant metabolic disturbances, CKD affects several organs, including the nervous system. Thus, CKD patients suffer from several neurological complications, including dementia, cognitive impairment, motor abnormalities, depression, and mood and sleep disturbances. However, the mechanisms underlying the neurological complications are least elucidated. We have recently reported a highly reproducible mice model of CKD induced by high adenine diet, which exhibited psychomotor behavioral abnormalities and blood-brain barrier disruption. In the present study, using the mice model, we have investigated psycho-motor and cognitive behaviour, and the neurochemical and histopathological alterations in brain relevant to the observed behavioural abnormalities. The results demonstrate global loss of Acetylcholinesterase activity, and decrease in neuronal arborisation and dendritic spine density in discrete brain regions, of the CKD mice. Oxidative stress, inflammation, and mitochondrial dysfunctions were found in specific brain regions of the mice, which have been regarded as the underlying causes of the observed neurochemical and histopathological alterations. Thus, the present study is of immense importance, and has therapeutic implications in the management of CKD-associated neurological complications.

A dual blocker of endothelin A/B receptors mitigates hypertension but not renal dysfunction in a rat model of chronic kidney disease and sleep apnea

Obstructive sleep apnea is characterized by recurrent episodes of pharyngeal collapse during sleep, resulting in intermittent hypoxia (IH), and is associated with a high incidence of hypertension and accelerated renal failure. In rodents, endothelin (ET)-1 contributes to IH-induced hypertension, and ET-1 levels inversely correlate with glomerular filtration rate in patients with end-stage chronic kidney disease (CKD). Therefore, we hypothesized that a dual ET receptor antagonist, macitentan (Actelion Pharmaceuticals), will attenuate and reverse hypertension and renal dysfunction in a rat model of combined IH and CKD. Male Sprague-Dawley rats received one of three diets (control, 0.2% adenine, and 0.2% adenine + 30 mg·kg^-1·day^-1 macitentan) for 2 wk followed by 2 wk of recovery diet. Rats were then exposed for 4 wk to air or IH (20 short exposures/h to 5% O₂-5% CO₂ 7 h/day during sleep). Macitentan prevented the increases in mean arterial blood pressure caused by CKD, IH, and the combination of CKD + IH. However, macitentan did not improve kidney function, fibrosis, and inflammation. After CKD was established, rats were exposed to air or IH for 2 wk, and macitentan feeding continued for 2 more wk. Macitentan reversed the hypertension in IH, CKD, and CKD + IH groups without improving renal function. Our data suggest that macitentan could be an effective antihypertensive in patients with CKD and irreversible kidney damage as a way to protect the heart, brain, and eyes from elevated arterial pressure, but it does not reverse toxin-induced tubule atrophy.

A novel approach to adenine-induced chronic kidney disease associated anemia in rodents

To date, good experimental animal models of renal anemia are not available. Therefore, the purpose of this study was to establish a novel approach to induce chronic kidney disease (CKD) with severe anemia by oral administration of adenine in rodents. Adenine was administered to 6-week-old male C57BL/6 mice (25 and 50 mg/kg body weight) by oral gavage daily for 28 days. Serum creatinine and BUN as well as hematocrit, hemoglobin (Hb) and plasma erythropoietin (EPO) levels were monitored to assess renal function and anemia, respectively. Adenine at 25 mg/kg for 28 days slightly increased plasma creatinine levels, but did not induce anemia. In contrast, 50 mg/kg of adenine daily for 28 days showed severe renal dysfunction (plasma creatinine 1.9 ± 0.10 mg/dL) and anemia (hematocrit 36.5 ± 1.0% and EPO 28 ± 2.4 pg/mL) as compared with vehicle-treated mice (0.4 ± 0.02 mg/dL, 49.6 ± 1.6% and 61 ± 4.0 pg/mL, respectively). At the end of experiment, level of Hb also significantly reduced in 50 mg/kg adenine administration group. Remarkable histological changes of kidney tissues characterized by interstitial fibrosis and cystic appearance in tubules were observed in 50 mg/kg of adenine treatment group. These results have demonstrated that oral dosing with adenine at 50 mg/kg for 28 days is suitable to induce a stable anemia associated with CKD in mice.

Human recombinant erythropoietin reduces sensorimotor dysfunction and cognitive impairment in rat models of chronic kidney disease

INTRODUCTION

Chronic kidney disease (CKD) can cause anaemia and neurological disorders. Recombinant human erythropoietin (rHuEPO) is used to manage anaemia in CKD. However, there is little evidence on the effects of rHuEPO on behaviour and cognitive function in CKD. This study aimed to evaluate the impact of rHuEPO in sensorimotor and cognitive functions in a CKD model.

METHODS

Male Wistar rats were randomly assigned to 4 groups: control and CKD, with and without rHuEPO treatment (1050 IU per kg body weight, once weekly for 4 weeks). The Morris water maze, open field, and adhesive removal tests were performed simultaneously to kidney damage induction and treatment. Markers of anaemia and renal function were measured at the end of the study.

RESULTS

Treatment with rHuEPO reduced kidney damage and corrected anaemia in rats with CKD. We observed reduced sensorimotor dysfunction in animals with CKD and treated with rHuEPO. These rats also completed the water maze test in a shorter time than the control groups.

CONCLUSIONS

rHuEPO reduces kidney damage, corrects anemia, and reduces sensorimotor and cognitive dysfunction in animals with CKD.

Delivery of human erythropoietin gene with an adeno-associated virus vector through parotid glands to treat renal anaemia in a swine model

Anaemia is a common complication of chronic kidney disease, for which there is presently no adequate treatment. The delivery of human erythropoietin (hEPO) cDNA to salivary glands reportedly increases red blood cell counts, haematocrit (HCT) and haemoglobin concentration, representing a potential new method of renal anaemia treatment. However, no studies have examined the effects of this method in an animal model of renal anaemia. Here we established a miniature pig animal model of renal anaemia through continuous feeding with adenine. In these animals, we delivered the AAV2hEPO gene to the parotid glands through Stensen's duct. As a control, we transferred AAVLacZ. Enzyme-linked immunosorbent assay was used to detect hEPO in serum and saliva. Red blood counts and serum biochemistry were used to evaluate how hEPO gene administration affected renal anaemia. Compared with the control group, we found increased hEPO concentrations in parotid saliva and serum, respectively, at 2 and 6 weeks after AAV2hEPO administration to the anaemic animals. HCT and haemoglobin were also increased after AAV2hEPO was delivered; most serum indicators of renal damage were not changed over the time span of the experiment, suggesting the adenine-induced kidney damage had not been completely reversed. However, blood urea nitrogen and B2 microglobulin levels showed small but significant improvement. Overall, our present findings suggest that adeno-associated virus 2 (AAV2)-mediated gene transduction of hEPO via the parotid gland is a promising potential alternative therapy for renal anaemia.

A highly reproducible mice model of chronic kidney disease: Evidences of behavioural abnormalities and blood-brain barrier disruption

AIMS

In the present study, a novel mice model of chronic kidney disease (CKD) was developed, and psycho-motor behavioural abnormalities, blood-brain barrier (BBB) integrity and brain histology were studied.

MAIN METHODS

Swiss albino female mice were given high adenine diet (0.3% w/w mixed with feed) for 4weeks. Serum urea and creatinine levels and renal histological studies were performed to validate the model. Psycho-motor behavioural abnormalities and neurological severity were studied. BBB integrity was assessed using Evans blue extravasation method. Nissl staining was performed to see possible morphological aberrations in brain.

KEY FINDINGS

There was a significant increase in serum urea and creatinine levels in mice given high adenine diet, and the mice had abnormal kidney morphology. Deposition of adenine and 2,8-dihydroxyadenine crystals, and increased collagen deposits in the renal tissues were found, which validate induction of CKD in the mice. Motor behavioural abnormalities, depression-like and anxiolytic behaviour and increase in neurological severity were prevalent in mice with CKD. Evans Blue dye extravasation was found to occur in the brain, which signifies disruption of BBB. However, Nissl staining did not reveal any morphological aberration in brain tissue.

SIGNIFICANCE

The present study puts forward a highly reproducible mice model of CKD validated with serum parameters and renal histopathological changes. The mice showed psycho-motor behavioural abnormalities and BBB disruption. It is a convenient model to study the disease pathology, and understanding the associated disorders, and their therapeutic interventions.

Gum Arabic as fetal hemoglobin inducing agent in sickle cell anemia; in vivo study

Background

High levels of fetal haemoglobin (HbF) decrease sickle cell anaemia (SCA) severity and leads to improved survival. According to in vivo and in vitro studies, butyrate increases HbF production. Its utilization in clinical practice is hampered, however, by its short half-life. Serum butyrate concentrations could be enhanced by colonic bacterial fermentation of Gum Arabic (GA), edible, dried, gummy exudates from Acacia Senegal tree. We hypothesized that regular intake of GA increases serum butyrate levels, thus inducing HbF production and ameliorating symptoms of sickle cell anemia.

Methods

Fourty seven patients (5–42 years) carrying hemoglobin SS were recruited from April 2014 to January 2015. Patients received 30 g/day GA for 12 weeks. HbF, blood count and erythropoietin level were measured. The main outcome of interest was the level of HbF after 12 weeks. The secondary outcomes were improvement in clinical and laboratory results. The study was ethically approved by Alneelain University IRB.

Results

The study revealed significant increase in HbF level P.V0.000 [95 % CI, 0.43–1.02], MCV P.V:000 [95 % CI, 2.312–6.058] and Hematocrit level P.V:0.026 [95 % CI, 0.124–1.902]. No significant difference was encountered in platelets count P.V: 0.346 [95 % CI,−25.76–71.94], and WBCs count P.V:0.194 [95 % CI,−8.035–1.68]. Thirty seven percent of patients experienced minor side effects which resolved within a week.

Conclusion

These findings reveal a novel effect of GA, which may be used to foster fetal hemoglobin production.

Trial registration

ClinicalTrials.gov Identifier: NCT02467257. Registered 3rd June 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s12878-015-0040-6) contains supplementary material, which is available to authorized users.

Animal models of pediatric chronic kidney disease. Is adenine intake an appropriate model?

Pediatric chronic kidney disease (CKD) has peculiar features. In particular, growth impairment is a major clinical manifestation of CKD that debuts in pediatric age because it presents in a large proportion of infants and children with CKD and has a profound impact on the self-esteem and social integration of the stunted patients. Several factors associated with CKD may lead to growth retardation by interfering with the normal physiology of growth plate, the organ where longitudinal growth rate takes place. The study of growth plate is hardly possible in humans and justifies the use of animal models. Young rats made uremic by 5/6 nephrectomy have been widely used as a model to investigate growth retardation in CKD. This article examines the characteristics of this model and analyzes the utilization of CKD induced by high adenine diet as an alternative research protocol.

Does swimming exercise affect experimental chronic kidney disease in rats treated with gum acacia?

Different modes of exercise are reported to be beneficial in subjects with chronic kidney disease (CKD). Similar benefits have also been ascribed to the dietary supplement gum acacia (GA). Using several physiological, biochemical, immunological, and histopathological measurements, we assessed the effect of swimming exercise (SE) on adenine –induced CKD, and tested whether SE would influence the salutary action of GA in rats with CKD. Eight groups of rats were used, the first four of which were fed normal chow for 5 weeks, feed mixed with adenine (0.25% w/w) to induce CKD, GA in the drinking water (15% w/v), or were given adenine plus GA, as above. Another four groups were similarly treated, but were subjected to SE during the experimental period, while the first four groups remained sedentary. The pre-SE program lasted for four days (before the start of the experimental treatments), during which the rats were made to swim for 5 to 10 min, and then gradually extended to 20 min per day. Thereafter, the rats in the 5^th, 6^th, 7^th, and 8^th groups started to receive their respective treatments, and were subjected to SE three days a week for 45 min each. Adenine induced the typical signs of CKD as confirmed by histopathology, and the other measurements, and GA significantly ameliorated all these signs. SE did not affect the salutary action of GA on renal histology, but it partially improved some of the above biochemical and physiological analytes, suggesting that addition of this mode of exercise to GA supplementation may improve further the benefits of GA supplementation.