Smad4 controls proliferation of interstitial cells in the neonatal kidney

Expansion of interstitial cells in the adult kidney is a hallmark of chronic disease, whereas their proliferation during fetal development is necessary for organ formation. An intriguing difference between adult and neonatal kidneys is that the neonatal kidney has the capacity to control interstitial cell proliferation when the target number has been reached. In this study, we define the consequences of inactivating the TGFβ/Smad response in the interstitial cell lineage. We find that pathway inactivation through loss of Smad4 leads to over-proliferation of interstitial cells regionally in the kidney medulla. Analysis of markers for BMP and TGFβ pathway activation reveals that loss of Smad4 primarily reduces TGFβ signaling in the interstitium. While TGFβ signaling is reduced in these cells, marker analysis shows that Wnt/β-catenin signaling is increased. Our analysis supports a model in which Wnt/β-catenin mediated proliferation is attenuated by TGFβ/Smad to ensure that proliferation ceases when the target number of interstitial cells has been reached in the neonatal medulla.

Incidence, Risk Factors, and Outcomes of Neonatal Acute Kidney Injury: Protocol of a Multicentric Prospective Cohort Study [The Indian Iconic Neonatal Kidney Educational Registry]

Background: Acute kidney injury (AKI) is a significant problem in neonates, but the evidence is sparse. Neonatal AKI is an independent risk factor for increased mortality and prolonged hospital stay. There are stark differences in the epidemiology of AKI in neonates amongst the developing and the developed world. Increased prevalence of neonatal sepsis, lack of awareness about neonatal AKI and poor access to pediatric nephrologists add to the improper management of neonatal AKI in the developing countries.Methods: This study is a multicentric, national, prospective cohort study [The Indian iconic Neonatal Kidney Educational Registry (TINKER)] conducted in level 2–3 NICUs in 11 centers across India. We have enrolled nearly 2,000 neonates over the study period. Neonates (≤ 28 days) who were admitted in NICU and those who received intravenous (IV) fluids for at least 48 h for hydration and/or nutrition have been included. Data collection included: (1) baseline demographics (2) daily physiologic and laboratory parameters (3) discharge data. KDIGO workgroup AKI definition modified for neonates was used for defining AKI. Data entry was carried out by individual participating centers using a web-based database (akiregistry.org). De-identified data has been maintained and handled by the principal investigator (PI). This collaboration plans to disseminate data through peer-reviewed publications and through presentations at educational conferences.Conclusions: The purpose of this study is to create the first prospective neonatal all-cause AKI data repository and describe the incidence of neonatal AKI in NICUs in the country and determine the risk factors as well as the outcomes of such neonates—both short-term and long-term outcomes. This will eventually spur therapeutic advancements, facilitate decipherment of epidemiological trends, risk factors as well as outcomes and identify disparities in management across the nation.

Effect of Successive Gentamicin and Amikacin Therapies on Renal Function of Neonates

Gentamicin and amikacin are aminoglycoside antibiotics which are renally excreted and known to cause nephrotoxicity. Neonatal eGFR per body surface area is lower than in adults and exposure to nephrotoxic drugs could lead to more suppression in kidney function. The aim of this study was to investigate the effect of administering successive courses of gentamicin (first-line) and amikacin (second-line) therapy on neonatal kidney function. Data were collected from patient records of neonates receiving gentamicin (July-December 2019) and amikacin (July-December 2020) at the Neonatal Unit of Windhoek Central Hospital (Namibia). 44 neonates on gentamicin and 35 on amikacin were included in this study. Aminoglycoside dose was administered as a slow intravenous bolus and two blood samples taken for pharmacokinetic analysis. Other information collected: gestational age, postnatal age (PNA), weight, height, serum creatinine, and dosage regimen. Primary outcomes were correlation of eGFR with PNA, and the time it took to clear the drug to < 1 µg/mL; eGFR was calculated using the Schwartz method. The negative correlation between eGFR and PNA was significant (r = -0.370, p = 0.034). Therapeutic range Cmax were achieved in 27.3% gentamicin neonates (15–25 µg/mL), and 17.1% in amikacin (55–65 µg/mL). Proportion of neonates with a Cmin <1 µg/mL within the 24-hour dosage interval were 72.7% and 82.9% for gentamicin and amikacin, respectively. Conclusion: The decline in kidney function for neonates while on amikacin was significant. However, a considerably high proportion of amikacin neonates (82.9%) were able to clear the drug to < 1 µg/mL within 24 hours.

Mitochondrial Damage and Mitochondria-Targeted Antioxidant Protection in LPS-Induced Acute Kidney Injury

Induced and frequently unwanted alterations in the mitochondrial structure and functions are a key component of the pathological cascade in many kidney pathologies, including those associated with acute damage. One of the principal pathogenic elements causing mitochondrial dysfunction in Acute Kidney Injury (AKI) is oxidative stress. After ischemia and nephrotoxic action of drugs, sepsis and systemic inflammation are the most frequent causes of AKI. As the kidney suffers from oxidative stress during sepsis, one of the most promising approaches to alleviate such damaging consequences is the use of antioxidants. Considering administration of lipopolysaccharide (LPS) as a model of sepsis, we demonstrate that the mitochondria of neonatal renal tissue are severely affected by LPS-induced AKI, with pathological ultrastructural changes observed in both the mitochondria of the renal tubular epithelium and the vascular endothelium. Upon mitochondrial damage, we evaluated the effect of the mitochondria-targeted antioxidant plastoquinol decylrhodamine 19 (SkQR1) on the development of acute renal failure in newborn rats associated with systemic inflammation induced by the administration of LPS. We found that SkQR1 administration 3 h before LPS led to decreased urinal expression of the AKI marker neutrophil gelatinase-associated lipocalin 2 (NGAL), in addition to a decrease in urea and creatinine levels in the blood. Additionally, an observed impairment of proliferative activity in the neonatal kidney caused by LPS treatment was also prevented by the treatment of rat pups with SkQR1. Thus, one of the key events for renal tissue damage in neonatal sepsis is an alteration in the structure and function of the mitochondria and the mitochondria-targeted antioxidant SkQR1 is an effective nephroprotective agent, which protects the neonatal kidney from sepsis-induced AKI.

Histological Comparative of Kidney of Neonatal Mice Exposed to Silver Nanoparticles During Fetal Development

This study aimed to compare the histological changes in the neonatal kidney after their mothers exposed to different doses of silver nanoparticles colloidal solution (AgNPs) during the three stages of pregnancy. Pregnant Swiss albino mice (n=60) were randomly divided into three treated groups. They were intraperitoneally injected with AgNPs for 7 days during each stage of the gestational period. The newborn mice were sacrificed immediately after the birth, and the kidneys were being collected for histopathological analysis. The results showed that the AgNPs caused histological changes in the neonatal kidneys; vacuolation of some renal vesicles and cortical tubules, cystic tubular dilation, glomerular tuft shrinkage, and focal tubular necrosis in the first week-dose exposed pregnant. Disintegrating of immature glomeruli, distention of Bowman’s space of mature glomeruli, tubular necrosis, loss of renal parenchyma, medullar tubules containing hyaline casts, and subcapsular haemorrhage in the second week-dose exposed pregnant. Massive hypercellularity in the deeper part of the renal cortex, cortical and medullary tubules dilation, atrophy of subcapsular immature tubules, cortical cyst formation, glomerular tuft necrosis, dilation of Bowman’s space with evidence of crescent formation, and medullar portion replaced by scant loose connective tissue containing few numbers of tubules the third week-dose exposed pregnant. The results showed that the AgNPs has more negative effects on the kidney development at the third week-high dose and comparing the histological changes in the neonatal kidney were appeared in a time-depended manner and in a dosedepended manner. More researches must be carried out to obtain better understanding of AgNPs toxicity on fetal development and its ability as a teratogenic agent to induce external and internal abnormalities in the fetus.