Renal glomerular and tubular responses to glutaraldehyde- polymerized human hemoglobin.

Hemoglobin-based oxygen carriers (HBOCs) are being developed as oxygen and volume replacement therapeutics, however, their molecular and cellular effects on the vasculature and different organ systems are not fully defined. Using a guinea pig transfusion model, we examined the renal glomerular and tubular responses to PolyHeme, a highly characterized glutaraldehyde-polymerized human hemoglobin with low tetrameric hemoglobin content. PolyHeme-infused animals showed no major changes in glomerular histology or loss of specific markers of glomerular podocytes (Wilms tumor 1 protein, podocin, and podocalyxin) or endothelial cells (ETS-related gene and claudin-5) after 4, 24, and 72 h. Relative to sham controls, PolyHeme-infused animals also showed similar expression and subcellular distribution of N-cadherin and E-cadherin, two key epithelial junctional proteins of proximal and distal tubules, respectively. In terms of heme catabolism and iron-handling responses, PolyHeme induced a moderate but transient expression of heme oxygenase-1 in proximal tubular epithelium and tubulointerstitial macrophages that was accompanied by increased iron deposition in tubular epithelium. Contrary to previous findings with other modified or acellular hemoglobins, the present data show that PolyHeme does not disrupt the junctional integrity of the renal glomerulus and tubular epithelium, and triggers moderate activation of heme catabolic and iron sequestration systems likely as part of a renal adaptive response.

Atractylodes lancea and Magnolia officinalis combination protects against high fructose-impaired insulin signaling in glomerular podocytes through upregulating Sirt1 to inhibit p53-driven miR-221.

ETHNOPHARMACOLOGICAL RELEVANCE: In traditional Chinese medicine, a long term of improper diet causes the Dampness and disturbs Zang-Fu's functions including Kidney deficiency. Atractylodes lancea (Atr) and Magnolia officinalis (Mag) as a famous herb pair are commonly used to transform Dampness, with kidney protection. AIM OF THE STUDY: To explore how Atr and Mag protected against insulin signaling impairment in glomerular podocytes induced by high dietary fructose feeding, a major contributor for insulin resistance in glomerular podocyte dysfunction. MATERIALS AND METHODS: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyze constituents of Atr and Mag. Rat model was induced by 10% fructose drinking water in vivo, and heat-sensitive human podocyte cells (HPCs) were exposed to 5 mM fructose in vitro. Animal or cultured podocyte models were treated with different doses of Atr, Mag or Atr and Mag combination. Western blot, qRT-PCR and immunofluorescence assays as well as other experiments were performed to detect adiponectin receptor protein 1 (AdipoR1), protein kinase B (AKT), Sirt1, p53 and miR-221 levels in rat glomeruli or HPCs, respectively. RESULTS: Fifty-five components were identified in Atr and Mag combination. Network pharmacology analysis indicated that Atr and Mag combination might affect insulin signaling pathway. This combination significantly improved systemic insulin resistance and prevented glomerulus morphological damage in high fructose-fed rats. Of note, high fructose decreased IRS1, AKT and AdipoR1 in rat glomeruli and cultured podocytes. Further data from cultured podocytes with Sirt1 inhibitor/agonist, p53 agonist/inhibitor, or miR-221 mimic/inhibitor showed that high fructose downregulated Sirt1 to stimulate p53-driven miR-221, resulting in insulin signaling impairment. Atr and Mag combination effectively increased Sirt1, and decreased p53 and miR-221 in in vivo and in vitro models. CONCLUSIONS: Atr and Mag combination improved insulin signaling in high fructose-stimulated glomerular podocytes possibly through upregulating Sirt1 to inhibit p53-driven miR-221. Thus, the regulation of Sirt1/p53/miR-221 by this combination may be a potential therapeutic approach in podocyte insulin signaling impairment.

Blockade of the natriuretic peptide clearance receptor attenuates proteinuria in a mouse model of focal segmental glomerulosclerosis.

Glomerular podocytes play a key role in proteinuric diseases. Accumulating evidence suggests that cGMP signaling has podocyte protective effects. The major source of cGMP generation in podocytes is natriuretic peptides. The natriuretic peptide clearance receptor (NPRC) binds and degrades natriuretic peptides. As a result, NPRC inhibits natriuretic peptide-induced cGMP generation. To enhance cGMP generation in podocytes, we blocked natriuretic peptide clearance using the specific NPRC ligand ANP(4-23). We then studied the effects of NPRC blockade in both cultured podocytes and in a mouse transgenic (TG) model of focal segmental glomerulosclerosis (FSGS) created in our laboratory. In this model, a single dose of the podocyte toxin puromycin aminonucleoside (PAN) causes robust albuminuria in TG mice, but only mild disease in non-TG animals. We found that natriuretic peptides protected cultured podocytes from PAN-induced apoptosis, and that ANP(4-23) enhanced natriuretic peptide-induced cGMP generation in vivo. PAN-induced heavy proteinuria in vehicle-treated TG mice, and this increase in albuminuria was reduced by treatment with ANP(4-23). Treatment with ANP(4-23) also reduced the number of mice with glomerular injury and enhanced urinary cGMP excretion, but these differences were not statistically significant. Systolic BP was similar in vehicle and ANP(4-23)-treated mice. These data suggest that: 1. Pharmacologic blockade of NPRC may be useful for treating glomerular diseases such as FSGS, and 2. Treatment outcomes might be improved by optimizing NPRC blockade to inhibit natriuretic peptide clearance more effectively.

Intervention Mechanism of Yishen Huayu Prescription on Glomerular Podocyte Injury in Diabetic Nephropathy Rats Based on EMT Regulated by Wnt/β-catenin Pathway / 中国实验方剂学杂志

Objective:To investigate the intervention mechanism of Yishen Huayu prescription on glomerular podocyte injury in diabetic nephropathy （DN） rats based on epithelialmesenchymal transition （EMT） regulated by Wnt/<italic>β</italic>-catenin pathway. Method:The 60 SD rats were divided into control group， model group， Wnt-C59 group （0.03 g·kg^-1 Wnt/<italic>β</italic>-catenin pathway inhibitor）， low-dose group （8 g·kg^-1）， medium-dose group （16 g·kg^-1） and high-dose group （32 g·kg^-1）. After 12 weeks， various indexes ， including general signs， serum creatinine （SCr）， blood urea nitrogen （BUN）， renal index， urinary protein， blood glucose， renal pathological changes， podocyte and expressions of glomerular basement membrane injury and podocyte injury related proteins ［nephrin， synaptopodin］， Wnt/<italic>β</italic>-catenin pathway related proteins （Wnt1， <italic>β</italic>-catenin）， podocyte EMT related protein ［<italic>α</italic>-smooth muscle actin （<italic>α</italic>-SMA）， E-cadherin］， were compared between groups. Result:Compared with the control group， the renal tissue in the model group showed significant pathological changes， including diffuse thickening of glomerular mesangial matrix and severe foot process fusion， and a significant increase in SCr， BUN， renal indexes， urinary protein， blood glucose， Wnt1， <italic>β</italic>-catenin， and <italic>α</italic>-SMA expression levels （<italic>P</italic><0.05） as well as a significant decrease in nephrin， synaptopodin and E-cadherin expression levels（<italic>P</italic><0.05）. Compared with model group， SCr， BUN， renal index， urinary protein， blood glucose， Wnt1， <italic>β</italic>-catenin， and <italic>α</italic>-SMA expression levels in each intervention group significantly decreased （<italic>P</italic><0.05）， while the expression levels of nephrin， synaptopodin and E-cadherin significantly increased （<italic>P</italic><0.05）. Among intervention groups， the improvement of above indexes in high-dose Yishen Huayu prescription group was the most obvious （<italic>P</italic><0.05）， which was similar to the effect in Wnt-C59 group. Conclusion:Yishen Huayu prescription prevents podocyte EMT by inhibiting Wnt/<italic>β</italic>-catenin pathway， thereby repairing glomerular podocyte injury in rats with diabetic nephropathy.

Podocyte-specific knockout of cyclooxygenase 2 exacerbates diabetic kidney disease.

Enhanced expression of cyclooxygenase 2 (COX2) in podocytes contributes to glomerular injury in diabetic kidney disease, but some basal level of podocyte COX2 expression might be required to promote podocyte attachment and/or survival. To investigate the role of podocyte COX2 expression in diabetic kidney disease, we deleted COX2 specifically in podocytes in a mouse model of Type 1 diabetes mellitus (Akita mice). Podocyte-specific knockout (KO) of COX2 did not affect renal morphology or albuminuria in nondiabetic mice. Albuminuria was significantly increased in wild-type (WT) and KO Akita mice compared with nondiabetic controls, and the increase in albuminuria was significantly greater in KO Akita mice compared with WT Akita mice at both 16 and 20 wk of age. At the 20-wk time point, mesangial expansion was also increased in WT and KO Akita mice compared with nondiabetic animals, and these histologic abnormalities were not improved by KO of COX2. Tubular injury was seen only in diabetic mice, but there were no significant differences between groups. Thus, KO of COX2 enhanced albuminuria and did not improve the histopathologic features of diabetic kidney disease. These data suggest that 1) KO of COX2 in podocytes does not ameliorate diabetic kidney disease in Akita mice, and 2) some basal level of podocyte COX2 expression in podocytes is necessary to attenuate the adverse effects of diabetes on glomerular filtration barrier function.

Effect of the knockdown of Cabin1 on p53 in glomerular podocyte.

Calcineurin binding protein 1 (Cabin1) is a natural inhibitor of calcineurin (CN). Moreover, Cabin1 retards tumor cell apoptosis by regulating p53. This study was designed to observe the expression of Cabin1 during podocyte injury, as well as its relationship with p53. Sprague-Dawley rats were used for the establishment of 5/6 nephrectomized rat model. Sham-operated rats underwent ventral laparotomy without nephrectomy. Then, rats were sacrificed at 8 and 12 weeks after nephrectomy. WT-1, a podocyte nuclear protein, was used for indicating the localization of Cabin1 in glomeruli. As tacrolimus protects podocyte via inhibiting AngiotensinII (AngII) induced CN activation. Cultured podocytes were injured by AngII or restored by tacrolimus. The protein expression and localization was detected by western blot or immunofluorescence staining. Cabin1 was knocked down by siRNA in cultured podocytes. In 5/6 nephrectomized rats, the colocalization of Cabin1 and WT-1 became more obviously in podocyte nuclei. Cabin1 protein was markedly increased in rats at 8 and 12 weeks after nephrectomy, as well as in AngII injured podocytes at 48 h (0.99 ± 0.12 in AngII group versus 0.80 ± 0.16 in control group). Cabin1 and p53 colocalized in cultured podocyte nuclei, p53 expression was significantly decreased (0.21 ± 0.05 in siRNA group versus 0.31 ± 0.05 in negative control group) after Cabin1 was being knocked down. In conclusion, Cabin1 expression significantly increases during podocyte injury. Knockdown of Cabin1 induces p53 expression decrease in cultured podocyte. Cabin1 may provide a new target to investigate podocyte injury.

Effect of insulin resistance on glomerular podocyte lesion of patients with IgA nephropathy / 中国综合临床

Objective To investigate the expression of insulin resistance on glomerular podocyte lesion of patients with IgA nephropathy.Methods Fifty-one patients with IgA nephropathy diagnosed by renal biopsy were selected as our subjects.The expression of WT1,a marker of podocyte of the renal tissue of patients with IgA nephropathy,was detected by immunohistochemistry.The density of podocyte per glomerulus was calculated by using specific software.The insulin sensitivity index (ISI) was severed as the degree of insulin resistance.Results There were strong negative correlations between ISI and WT1,mean arterial blood pressure,triglyceride,plasma uricemia,serum creatinine,body mass index,glomerular sclerosis integral,integral,mesangial proliferation of vascular lesions integral(r =-0.521,P ＜ 0.05 ;r =-0.544,P ＜ 0.05;r =-0.646,P ＜ 0.01 ;r =-0.559,P ＜0.05 ;r =-0.741,P ＜0.01 ;r =-0.561,P ＜0.05 ;r =-0.740,P ＜ 0.01 ;r =-0.695,P＜0.01;r =-0.535,P ＜ 0.05 respectively).There was no significant relationship between ISI and 24 h quantitative urinary protein (r =-1.425,P ＞ 0.05).Conclusion Insulin resistance was involved in glomerular podocyte lesion and may contribute to the progression of IgA nephropathy.