Ribes diacanthum Pall (RDP) ameliorates UUO-induced renal fibrosis via both canonical and non-canonical TGF-β signaling pathways in mice

Analysis of chemical constituents in different parts of Ribes diacanthum pall using molecular network assistance and their bioactive properties

Ribes diacanthum Pall (RDP) is a medicinal and edible plant recognized for its diverse bioactive constituents and has been widely utilized in Mongolian folk medicine for the treatment of various ailments. Decoctions and hydroethanolic extracts prepared from the aerial parts of RDP, including the fruits, stems, and leaves, have been employed in disease management. However, a comprehensive comparative analysis of the chemical profiles and bioactive properties of the fruits, stems, and leaves remains to be conducted. To bridge this gap, we conducted a detailed investigation into the chemical diversity and bioactive properties of the fruits, stems, and leaves of RDP. The phytochemical composition of the extracts was analyzed using HPLC-QTOF-MS/MS, and the in vitro bioactivities, including antioxidant, cytotoxic, anti-inflammatory, and hepatoprotective activities, were evaluated. A total of 55 compounds were identified across the various parts of RDP, with 28 detected in the fruits, 16 in the stems, and 33 in the leaves; notably, 5 compounds were common to all plant parts. Specifically, RDP fruits were characterized by unique amino acids (L-tyrosine and Abrine) as well as distinct flavonoids (Eriodictyol and Cyanidin-3-o-arabinose chloride) and phenylpropanoids (Ferulic acid and Caffeic acid methyl ester), whereas the stems contained unique fatty acid derivatives (9,10-Dihydroxy-8-oxooctadec-12-enoic acid), cyclic polyketides (Mycophenolic acid), and several tryptophan alkaloids (Paratunamide D). In contrast, the leaves were particularly rich in flavonoids (Kaempferol 3-O-rhamninoside and Kaempferol-7-O-neohesperidoside), phenolic acids (Gallic acid), and macrolides (Pyrenophorol). The DPPH and ABTS radical scavenging activities followed this order of IC50 values: for DPPH, RDP leaves (0.1047 mg/ml) > RDP stems (0.2173 mg/ml) > ; for ABTS, RDP leaves (0.2362 mg/ml) > RDP stems (0.5218 mg/ml) > RDP fruits (1.182 mg/ml). AML-12 cell models induced with LPS or TCA/CDCA were employed to evaluate the cytotoxicity and anti-inflammatory effect of the extracts and their potential hepatoprotective effects. The results indicated that the various parts of RDP exhibited significant anti-inflammatory effects against LPS-induced inflammation in AML-12 cells and alleviated TCA or CDCA-induced hepatotoxicity. Notably, RDP leaves demonstrated the most effective protective effect against TCA or CDCA-induced cytotoxicity, followed by the stems and fruits. In summary, these findings provide a scientific basis for the extensive application of phytochemicals and bioactive compounds derived from the fruits, stems, and leaves of RDP.

Ribes diacanthum Pall modulates bile acid homeostasis and oxidative stress in cholestatic mice by activating the SIRT1/FXR and Keap1/Nrf2 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Cholestatic liver injury (CLI) is a pathophysiological syndrome characterized by the accumulation of bile acids (BAs), which leads to significant hepatic dysfunction. This condition is frequently associated with disturbances in BAs homeostasis and the induction of oxidative stress. Ribes diacanthum Pall (RDP), a conventional folk medicinal plant, has been employed in Mongolia, the Inner Mongolia region of China, and other areas for the remediation of hepatic disorders. However, the specific mechanism and chemical composition by which RDP exerts its effects remain unknown.

AIM OF THE STUDY

The aim of this research was to assess the protective impact of RDP on CLI and probe into the underlying mechanism and pinpoint the active constituents of RDP.

MATERIALS AND METHODS

For this study, a CLI mouse model induced via bile duct ligation (BDL) was used to investigate the hepatoprotective effect of RDP. Mice were administered low, medium, or high doses of RDP for 6 consecutive days, beginning 3 days prior to BDL induction. Subsequently, serum biochemical parameters, hepatic histopathology, and cholestatic markers were analyzed. An HPLC-QTOF-MS/MS analysis was also conducted to identify the prototype constituents in RDP. Furthermore, component-directed network pharmacology was utilized to identify the active constituents, central targets, and signaling cascades of RDP. Eventually, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were adopted to confirm the associated antioxidant enzymes, BAs transporters, and metabolic enzymes. Molecular docking was applied to forecast the binding affinity between the components and core targets.

RESULTS

RDP effectively ameliorated the pathological liver damage and cholestasis in BDL-induced CLI mice. Moreover, 43 components within RDP were identified through HPLC-QTOF-MS/MS analysis. Altogether 106 potential targets were detected, and the high-affinity targets, namely Keap1 and SIRT1, were located through the PPI network. The results of GO and KEGG analysis indicated that the reaction to oxidative stress and BAs homeostasis are significantly associated with the RDP treatment of CLI. In the in vivo experimental study, the findings revealed that RDP alleviated the BDL-induced oxidative damage. Simultaneously, RDP augmented the expressions of BAs efflux transporters and the metabolic enzymes in liver tissues, thus promoting BAs excretion and metabolism in cholestatic rodents. Mechanically, RDP attenuated hepatic oxidative stress and the accumulation of BAs, protecting the liver from BDL-induced cholestasis via the Keap1/Nrf2 and SIRT1/FXR signaling axis. The molecular docking result indicated that bolusanthol C and 3,6,3',4'-tetrahydroxyflavone possess a superior binding affinity to the two core targets (Keap1, SIRT1).

CONCLUSION

These results suggest that RDP ameliorate CLI by regulating BAs homeostasis and alleviating oxidative stress through the SIRT1/FXR and Keap1/Nrf2 signaling pathways, presenting a novel therapeutic strategy for cholestasis. Additionally, bolusanthol C and 3,6,3',4'-tetrahydroxyflavone may function as key pharmacological agents in RDP, responsible for its protective effects against CLI.

Herb pair of Rhubarb-Astragalus mitigates renal interstitial fibrosis through downregulation of autophagy via p38-MAPK/TGF-β1 and p38-MAPK/smad2/3 pathways

BACKGROUND

Chronic kidney disease (CKD) has a high incidence and poor prognosis; however, no effective treatment is currently available. Our previous study found that the improvement effect of the herb pair of Rhubarb-Astragalus on CKD is likely related to the inhibition of the TGF-β1/p38-MAPK pathway. In the present study, a p38-MAPK inhibitor was used to further investigate the inhibitory effect of Rhubarb-Astragalus on the TGF-β1/p38-MAPK pathway and its relationship with autophagy.

METHODS

A rat model of unilateral ureteral obstruction (UUO) was established, and a subgroup of rats was administered Rhubarb-Astragalus. Renal function and renal interstitial fibrosis (RIF) were assessed 21 d after UUO induction. In vitro, HK-2 cells were treated with TGF-β1 and a subset of cells were treated with Rhubarb-Astragalus or p38-MAPK inhibitor. Western blotting, immunohistochemistry, and qRT-PCR analyses were used to detect the relevant protein and mRNA levels. Transmission electron microscopy was used to observe autophagosomes.

RESULTS

Rhubarb-Astragalus treatment markedly decreased the elevated levels of blood urea nitrogen, serum creatinine, and urinary N-acetyl-β-D-glucosaminidase; attenuated renal damage and RIF induced by UUO; and reduced the number of autophagosomes and lysosomes in UUO-induced renal tissues. Additionally, Rhubarb-Astragalus reduced the protein and mRNA levels of α-SMA, collagen I, LC3, Atg3, TGF-β1, p38-MAPK, smad2/3, and TAK1 in renal tissues of UUO rats. Rhubarb-Astragalus also reduced protein and mRNA levels of these indicators in vitro. Importantly, the effect of the p38-MAPK inhibitor was similar to that of Rhubarb-Astragalus.

CONCLUSIONS

Rhubarb-Astragalus improves CKD possibly by downregulating autophagy via the p38-MAPK/TGF-β1 and p38-MAPK/smad2/3 pathways.

Reno-protective effect of protocatechuic acid is independent of sex-related differences in murine model of UUO-induced kidney injury

BACKGROUND

Obstructive nephropathy is a condition often caused by urinary tract obstruction either anatomical (e.g., tumors), mechanical (e.g., urolithiasis), or compression (e.g., pregnancy) and can progress to chronic kidney disease (CKD). Studies have shown sexual dimorphism in CKD, where males were found to have a more rapid decline in kidney function following kidney injury compared to age-matched females. Protocatechuic acid (PCA), an anti-oxidant and anti-inflammatory polyphenolic compound, has demonstrated promising effects in mitigating drug-induced kidney injuries. The current study aims to explore sexual dimorphism in kidney injury after unilateral ureteral obstruction (UUO) and assess whether PCA treatment can mitigate kidney injury in both sexes.

METHODS

UUO was induced in 10-12 weeks old male and female C57BL/6J mice. Mice were categorized into four groups (n = 6-8/group); Sham, Sham plus PCA (100 mg/kg, I.P daily), UUO, and UUO plus PCA.

RESULTS

After 2 weeks of induction of UUO, markers of kidney oxidative stress (TBARs), inflammation (IL-1α and IL-6), tubular injury (neutrophil gelatinase-associated lipocalin, NGAL and urinary kidney injury molecule-1, KIM-1), fibrosis (Masson's trichrome staining, collagen IV expression, MMP-2 and MMP-9) and apoptosis (TUNEL+ cells, active caspase-1 and caspase-3) were significantly elevated in both males and females relative to their sham counterparts. Males exhibited significantly greater kidney oxidative stress, inflammation, fibrosis, and apoptosis after induction of UUO when compared to females. PCA treatment significantly attenuated UUO-induced kidney injury, inflammation, fibrosis, and apoptosis in both sexes.

CONCLUSION

Our findings suggest a differential gender response to UUO-induced kidney injury with males being more sensitive to UUO-induced kidney inflammation, fibrosis, and apoptosis than age-matched females. Importantly, PCA treatment reduced UUO-induced kidney injury in a sex-independent manner which might be attributed to its anti-oxidant, anti-inflammatory, anti-fibrotic, and anti-apoptotic properties.

Linagliptin Mitigates TGF-β1 Mediated Epithelial-Mesenchymal Transition in Tacrolimus-Induced Renal Interstitial Fibrosis via Smad/ERK/P38 and HIF-1α/LOXL2 Signaling Pathways

The dipeptidyl peptidase-4 (DPP-4) inhibitors, a novel anti-diabetic medication family, are renoprotective in diabetes, but a comparable benefit in chronic non-diabetic kidney diseases is still under investigation. This study aimed to elucidate the molecular mechanisms of linagliptin's (Lina) protective role in a rat model of chronic kidney injury caused by tacrolimus (TAC) independent of blood glucose levels. Thirty-two adult male Sprague Dawley rats were equally randomized into four groups and treated daily for 28 d as follows: The control group; received olive oil (1 mL/kg/d, subcutaneously), group 2; received Lina (5 mg/kg/d, orally), group 3; received TAC (1.5 mg/kg/d, subcutaneously), group 4; received TAC plus Lina concomitantly in doses as the same previous groups. Blood and urine samples were collected to investigate renal function indices and tubular injury markers. Additionally, signaling molecules, epithelial-mesenchymal transition (EMT), and fibrotic-related proteins in kidney tissue were assessed by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis, immunohistochemical and histological examinations. Tacrolimus markedly induced renal injury and fibrosis as indicated by renal dysfunction, histological damage, and deposition of extracellular matrix (ECM) proteins. It also increased transforming growth factor β1 (TGF-β1), Smad4, p-extracellular signal-regulated kinase (ERK)1/2/ERK1/2, and p-P38/P38 mitogen-activated protein kinase (MAPK) protein levels. These alterations were markedly attenuated by the Lina administration. Moreover, Lina significantly inhibited EMT, evidenced by inhibiting Vimentin and α-smooth muscle actin (α-SMA) and elevating E-cadherin. Furthermore, Lina diminished hypoxia-related protein levels with a subsequent reduction in Snail and Twist expressions. We concluded that Lina may protect against TAC-induced interstitial fibrosis by modulating TGF-β1 mediated EMT via Smad-dependent and independent signaling pathways.

BMAL1 inhibits renal fibrosis and renal interstitial inflammation by targeting the ERK1/2/ELK-1/Egr-1 axis

RATIONALE

Renal fibrosis and renal interstitial inflammation due to hydronephrosis are associated with progressive chronic kidney disease (CKD). The clock gene BMAL1 is thought to be involved in various diseases, including hypertension, diabetes, etc. However, little is known about how BMAL1 regulates renal fibrosis and renal interstitial inflammation in obstructed kidneys.

METHODS

The expression level of BMAL1 in UUO was examined using the GEO database. Lentivirus, siRNA and adeno-associated virus were used to modulate BMAL1 levels in HK-2 cells and mouse kidney. qRT-PCR, immunofluorescence staining, histological analysis, ELISA and Western blot were used to determine the level of fibrin deposition and the release of inflammatory factors. Immunofluorescence staining and western blotting were used to examine the interaction between BMAL1 and the ERK1/2/ELK-1/Egr-1 axis.

RESULTS

Bioinformatics analysis and in vivo experiments in this study showed that the expression level of BMAL1 in UUO model kidneys was higher than that in normal kidneys. We then found that downregulation of BMAL1 promoted the production of extracellular matrix (ECM) proteins and proinflammatory factors in vivo and in vitro, whereas upregulation inhibited this process. In addition, we demonstrated that the ERK1/2/ELK-1/Egr-1 axis is an important pathway for BMAL1 to play a regulatory role, and the use of PD98059 abolished the promoting effect of down-regulation of BMAL1 on fibrosis and inflammation.

CONCLUSIONS

Our findings suggest that BAML1 can target the ERK1/2/ELK-1/Egr-1 axis to suppress fibrotic progression and inflammatory events in obstructed kidneys, thereby inhibiting the development of CKD.

Piperlonguminine attenuates renal fibrosis by inhibiting TRPC6

ETHNOPHARMACOLOGICAL RELEVANCE

Liuwei Dihuang (LWDH) is a classic prescription that has been used to the treatment of "Kidney-Yin" deficiency syndrome for more than 1000 years in China. Recent studies have confirmed that LWDH can prevent the progression of renal fibrosis. Numerous studies have demonstrated the critical role that TRPC6 plays in the development of renal fibrosis. Due to the complex composition of LWDH and its remarkable therapeutic effect on renal fibrosis, it is possible to discover new active ingredients targeting TRPC6 for the treatment of renal fibrosis.

AIM OF STUDY

This study aimed to identify selective TRPC6 inhibitors from LWDH and evaluate their therapeutical effects on renal fibrosis.

MATERIALS AND METHODS

Computer-aided drug design was used to screen the biologically active ingredients of LWDH, and their affinities to human TRPC6 protein were detected by microcalorimetry. TRPC6, TRPC3, and TRPC7 over-expressed HEK293 cells were constructed, and the selective activities of the compounds on TRPC6 were determined by measuring [Ca²⁺]_i in these cells. To establish an in vitro model of renal fibrosis, human renal proximal tubular epithelial HK-2 cells were stimulated with TGF-β1. The therapeutic effects of LWDH compounds on renal fibrosis were then tested by detecting the related proteins. TRPC6 was knocked-down in HK-2 cells to investigate the effects of LWDH active ingredients on TRPC6. Finally, a unilateral ureteral obstruction model of renal fibrosis was established to test the therapeutic effect.

RESULTS

From hundreds of LWDH ingredients, 64 active components with oral bioavailability ≥30% and drug-likeness index ≥0.18 were acquired. A total of 10 active components were obtained by molecular docking with TRPC6 protein. Among them, 4 components had an affinity with TRPC6. Piperlonguminine (PLG) had the most potent affinity with TRPC6 and blocking effect on TRPC6-mediated Ca²⁺ entry. A 100 μM of PLG showed no detectable inhibition on TRPC1, TRPC3, TRPC4, TRPC5, or TRPC7-mediated Ca²⁺ influx into cells. In vitro results indicated that PLG concentration-dependently inhibited the abnormally high expression of α-smooth muscle actin (α-SMA), collagen I, vimentin, and TRPC6 in TGF-β1-induced HK-2 cells. Consistently, PLG also could not further inhibit TGF-β1-induced expressions of these protein biomarkers in TRPC6 knocked-down HK-2 cells. In vivo, PLG dose-dependently reduced urinary protein, serum creatinine, and blood urea nitrogen levels in renal fibrosis mice and markedly alleviated fibrosis and the expressions of α-SMA, collagen I, vimentin, and TRPC6 in kidney tissues.

CONCLUSION

Our results showed that PLG had anti-renal fibrosis effects by selectively inhibiting TRPC6. PLG might be a promising therapeutic agent for the treatment of renal fibrosis.

Acteoside alleviates UUO-induced inflammation and fibrosis by regulating the HMGN1/TLR4/TREM1 signaling pathway

PURPOSE

Acteoside (Act), a phenylethanoid compound that was first isolated from mullein, has been widely used for the investigation of anti-inflammatory and anti-fibrotic effect. However, the mechanism of Act against unilateral ureteral obstruction (UUO)-mediated renal injury is largely unknown. Therefore, this study aimed to explore the effects of Act on UUO rats and possible mechanisms.

METHODS

A total of 20 Sprague-Dawley (SD) rats were divided randomly into three groups (n ≥ 6): (i) sham-operated group (Sham); (ii) UUO group (UUO+Saline); and (iii) UUO + Act 40 mg/kg/day, (UUO+Act); Continuous gavage administration for 2 weeks postoperatively, while the rats in Sham and UUO+saline groups were given equal amounts of saline. All rats were sacrificed after 14 days, the urine and blood samples were collected for biochemical analysis, the renal tissues were collected for pathological staining and immunohistochemistry. Correlations between individual proteins were analyzed by Pearson correlation analysis.

RESULTS

The results of renal function indexes and histopathological staining showed that Act could improve renal function by reducing serum creatinine, blood urea nitrogen and urine protein at the same time, Act could alleviate renal inflammation and fibrosis. In addition, the results of immunohistochemistry showed that Act could reduce the expression of inflammation and kidney injury-related proteins F4/80, Mcp-1, KIM-1 proteins, as well as the expression of fibrosis-related protein α-SMA and β-catenin. More importantly, Act can also reduce the expression of HMGN1, TLR4 and TREM-1 proteins.

CONCLUSION

These data demonstrate that Act can ameliorate UUO-induced renal inflammation and fibrosis in rats probably through triggering HMGN1/TLR4/TREM-1 pathway.

Synthesis of AC1903 analogs as potent transient receptor potential canonical channel 4/5 inhibitors and biological evaluation

Transient receptor potential canonical (TRPC) channels are a class of non-selective cation channels expressed in a variety of tissues and organ systems where they functionally regulate physiological and pathological processes. TRPC5 has been shown to be a promising target for focal segmental glomerulosclerosis treatment. In this study, we report the synthesis and biological evaluation of a novel series of benzimidazole-based TRPC5 inhibitors. One compound, 8b, is 100-fold more potent than the parent compound, AC1903, in the suppression of TRPC5 channel activity. Interestingly, both AC1903 and 8b also suppressed TRPC4 channel activity with similar potency. Compound 8b also significantly blunts protamine sulfate-induced reorganization of podocyte cytoskeleton, interleukin (IL)-17-induced cell proliferation, and the expression of proinflammatory mediators in human keratinocyte HaCaT cells.

Renoprotective activity of Ribes diacanthum pall (RDP) against inflammation in cisplatin-stimulated mice model and human renal tubular epithelial cells

ETHNOPHARMACOLOGICAL RELEVANCE

Ribes diacanthum Pall (RDP) is mostly distributed in Mongolia. As a Mongolian folk medicinal plant, it is traditionally used to treat kidney diseases by the native inhabitants of Mongolia due to its effect of increasing urine output and eliminating edema. However, its renal protection mechanism remains to be elucidated.

AIM OF THE STUDY

To assess the pharmacological mechanism of RDP from an anti-inflammatory point of view using cisplatin (CDDP)-induced kidney injury models in vivo and in vitro. The influence of RDP on the chemotherapy efficacy of CDDP was also evaluated in vitro.

MATERIALS AND METHODS

We established a CDDP-induced nephrotoxicity mouse model and a Human Renal Tubular Epithelial (HK-2) damage cellular model, respectively. In vivo, kidney function, the content of urine albumin, and renal histopathology examination were performed to observe the kidney injury. Moreover, the expression and secretion of inflammatory cytokines and adhesive molecules were examined by enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC), and real-time PCR. The key protein levels of mitogen-activated protein kinase/nuclear factor kappa B (MAPK/NF-κB) signaling pathway were measured by western blotting analysis. Electrophoretic mobility shift assay (EMSA) was carried out to detect the activation of NF-κB. In vitro, inflammatory mediators and the proteins related to the NF-κB signaling pathway in HK-2 cells were measured by western blotting analysis. Besides, A549 cell lines were treated with CDDP and RDP to explore RDP's impact on CDDP chemotherapy.

RESULTS

Gavage RDP decreased the elevated levels of serum creatinine (Scr), urea nitrogen (BUN), as well as the ratio of urine albumin and creatinine, ameliorated pathological changes of kidney tissue. Correspondingly, the RDP administration group showed a higher survival rate than that of the CDDP exposed group. The expression levels of a plethora of inflammatory mediators were inhibited by RDP treatment compared with the CDDP-exposed group. Furthermore, protein expression levels of MAPK/NF-κB signaling pathway significantly decreased after RDP intervention. For in vitro studies, we confirmed the inhibitory effect of RDP on relative protein expressions involving in the NF-κB pathway. The results also showed that RDP had no impairment on the inhibitory effect of CDDP on A549 cells.

CONCLUSION

These findings demonstrated RDP's anti-inflammatory effect against CDDP nephrotoxicity through in vivo and in vitro experiments, and suggested that RDP may have a potential application as an adjuvant medication for CDDP chemotherapy and other inflammatory kidney diseases.

Ceria nanoparticles ameliorate renal fibrosis by modulating the balance between oxidative phosphorylation and aerobic glycolysis

BACKGROUND AND AIMS

Renal fibrosis is the common outcome in all progressive forms of chronic kidney disease. Unfortunately, the pathogenesis of renal fibrosis remains largely unexplored, among which metabolic reprogramming plays an extremely crucial role in the evolution of renal fibrosis. Ceria nanoparticles (CeNP-PEG) with strong ROS scavenging and anti-inflammatory activities have been applied for mitochondrial oxidative stress and inflammatory diseases. The present study aims to determine whether CeNP-PEG has therapeutic value for renal fibrosis.

METHODS

The unilateral ureteral obstructive fibrosis model was used to assess the therapeutic effects in vivo. Transforming growth factor beta1-induced epithelial-to-mesenchymal transition in HK-2 cells was used as the in vitro cell model. The seahorse bioscience X96 extracellular flux analyzer was used to measure the oxygen consumption rate and extracellular acidification rate.

RESULTS

In the present study, CeNP-PEG treatment significantly ameliorated renal fibrosis by increased E-cadherin protein expression, and decreased α-SMA, Vimentin and Fibronectin expression both in vitro and in vivo. Additionally, CeNP-PEG significantly reduced the ROS formation and improved the levels of mitochondrial ATP. The seahorse analyzer assay demonstrated that the extracellular acidification rate markedly decreased, whereas the oxygen consumption rate markedly increased, in the presence of CeNP-PEG. Furthermore, the mitochondrial membrane potential markedly enhanced, hexokinase 1 and hexokinase 2 expression significantly decreased after treatment with CeNP-PEG.

CONCLUSIONS

CeNP-PEG can block the dysregulated metabolic status and exert protective function on renal fibrosis. This may provide another therapeutic option for renal fibrosis.

Targeting Mechanosensitive Piezo1 Alleviated Renal Fibrosis Through p38MAPK-YAP Pathway

Renal fibrosis is the most common pathological manifestation of a wide variety of chronic kidney disease. Increased extracellular matrix (ECM) secretion and enhanced microenvironment stiffening aggravate the progression of renal fibrosis. However, the related mechanisms remain unclear. Here, we evaluated the mechanism by which ECM stiffness aggravates renal fibrosis. In the present study, renal mesangial cells (MCs) were cultured on polyacrylamide hydrogels with different stiffness accurately detected by atomic force microscope (AFM), simulating the in vivo growth microenvironment of MCs in normal kidney and renal fibrosis. A series of in vitro knockdown and activation experiments were performed to establish the signaling pathway responsible for mechanics-induced MCs activation. In addition, an animal model of renal fibrosis was established in mice induced by unilateral ureteral obstruction (UUO). Lentiviral particles containing short hairpin RNA (sh RNA) targeting Piezo1 were used to explore the effect of Piezo1 knockdown on matrix stiffness-induced MCs activation and UUO-induced renal fibrosis. An in vitro experiment demonstrated that elevated ECM stiffness triggered the activation of Piezo1, which increased YAP nuclear translocation through the p38MAPK, and consequently led to increased ECM secretion. Furthermore, these consequences have been verified in the animal model of renal fibrosis induced by UUO and Piezo1 knockdown could alleviate UUO-induced fibrosis and improve renal function in vivo. Collectively, our results for the first time demonstrate enhanced matrix stiffness aggravates the progression of renal fibrosis through the Piezo1-p38MAPK-YAP pathway. Targeting mechanosensitive Piezo1 might be a potential therapeutic strategy for delaying the progression of renal fibrosis.

Sarco/endoplasmic reticulum Ca2+ -ATPase 2b mediates oxidation-induced endoplasmic reticulum stress to regulate neuropathic pain

BACKGROUND AND PURPOSE

Neuropathic pain is a widespread health problem with limited curative treatment. Decreased sarco/endoplasmic reticulum Ca²⁺ -ATPase (SERCA) expression has been reported in dorsal root ganglion (DRG) of animals suffering from neuropathic pain. We aimed to establish the relationship between SERCA expression and the pain responses and to elucidate the underlying molecular mechanism.

EXPERIMENTAL APPROACH

Neuropathic pain was modeled using rat chronic constriction injury (CCI). Ca²⁺ imaging and current clamp patch-clamp were used to determine cytosolic Ca²⁺ levels and action potential firing, respectively. Western blots, immunofluorescence staining and RT-PCR were used to quantitatively assess protein and mRNA expression, respectively. H&E staining and coupled enzyme assay were used to evaluate the nerve injury and SERCA2b activity, respectively.

KEY RESULTS

SERCA2b is the predominant SERCA isoform in rat DRG and its expression is decreased after CCI at mRNA, protein and activity levels. Whereas inhibiting SERCA with thapsigargin causes neuronal hyperexcitation, nerve injury, ER stress, satellite glial cell activation and mechanical allodynia, activating SERCA by CDN1163 or overexpressing SERCA2b in DRG after CCI produces long-term relief of mechanical and thermal allodynia with accompanied morphological and functional restoration through alleviation of ER stress. Furthermore, the downregulation of DRG SERCA2b in CCI rats is caused by increased production of reactive oxygen species (ROS) through Sp1-dependent transcriptional inhibition.

CONCLUSION AND IMPLICATIONS

Our findings reveal a novel pathway centering around SERCA2b as the key molecule underlying the mechanism of development and maintenance of neuropathic pain, and SERCA2b activators have the potential for therapeutic treatment of neuropathic pain.

Anwulignan alleviates d-galactose induced renal damage by regulating Nrf2/ARE signaling pathway in mice

Free radical accumulation in the body will cause oxidative stress damages including the renal damage. Schisandrae Sphenantherae Fructus (Schisandra), a traditional Chinese herbal medicine, has been used throughout the world. Anwulignan, a monomer extracted from Schisandra, has been shown in our previous studies to possess antioxidant and protective effects on the liver, brain and spleen damages in the aging mice. However, its effect on the renal damage caused by aging is not clear. This study showed that anwulignan could significantly increase the kidney index, the creatinine clearance, the activities of superoxide dismutase, catalase and glutathione peroxidase; reduce the urinary protein concentration, the serum urea nitrogen and creatinine content, the content of malondialdehyde and 8-hydroxylated deoxyguanosine in the renal tissue; and improve the renal tissue damage. Moreover, anwulignan increased the production of Nrf2, HO-1 and NQO1 proteins and decreased the production level of Keap1 protein in the renal tissue in the d-galactose induced aging mice. These results suggest that anwulignan significantly alleviates the renal damage by its antioxidant effect through regulating the production of Nrf2/ARE pathway-related proteins in the renal tissue in the d-galactose induced aging mice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-021-00951-7.

The Epithelial-to-Mesenchymal Transition as a Possible Therapeutic Target in Fibrotic Disorders

Fibrosis is a chronic and progressive disorder characterized by excessive deposition of extracellular matrix, which leads to scarring and loss of function of the affected organ or tissue. Indeed, the fibrotic process affects a variety of organs and tissues, with specific molecular background. However, two common hallmarks are shared: the crucial role of the transforming growth factor-beta (TGF-β) and the involvement of the inflammation process, that is essential for initiating the fibrotic degeneration. TGF-β in particular but also other cytokines regulate the most common molecular mechanism at the basis of fibrosis, the Epithelial-to-Mesenchymal Transition (EMT). EMT has been extensively studied, but not yet fully explored as a possible therapeutic target for fibrosis. A deeper understanding of the crosstalk between fibrosis and EMT may represent an opportunity for the development of a broadly effective anti-fibrotic therapy. Here we report the evidences of the relationship between EMT and multi-organ fibrosis, and the possible therapeutic approaches that may be developed by exploiting this relationship.

Integrated Network Pharmacology Analysis and Pharmacological Evaluation to Explore the Active Components and Mechanism of Abelmoschus manihot (L.) Medik. on Renal Fibrosis

Background

Renal fibrosis is a common pathological outcome of chronic kidney diseases (CKD) that is considered as a global public health issue with high morbidity and mortality. The dry corolla of Abelmoschus manihot (L.) Medik. (AMC) has been used for chronic nephritis in clinic and showed a superior effect in alleviating proteinuria in CKD patients to losartan. However, the effective components and underlying mechanism of AMC in the treatment of renal fibrosis have not been systematically clarified.

Methods

Based on drug-likeness evaluation, oral bioavailability prediction and compound contents, a systematic network pharmacology analysis was conducted to predict the active ingredients. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway analysis and protein–protein interaction analysis were applied to predict the potential pathway and target of AMC against renal fibrosis. The formula of component contribution index (CI) based on the algorithm was used to screen the principal active compounds of AMC in the treatment of renal fibrosis. Finally, pharmacological evaluation was conducted to validate the protective effect and primary predicted mechanism of AMC in the treatment of renal fibrosis on a 5/6 nephrectomy mice model.

Results

Fourteen potential active components of AMC possessing favorable pharmacokinetic profiles and biological activities were selected and hit by 17 targets closely related to renal fibrosis. Quercetin, caffeic acid, 9.12-octadecadienoic acid, and myricetin are recognized as the more highly predictive components as their cumulative contribution rate reached 85.86%. The AMC administration on 5/6 nephrectomy mice showed a protective effect on kidney function and renal fibrosis. The hub genes analysis revealed that AMC plays a major role in inhibiting epithelial-to-mesenchymal transition during renal fibrosis.

Conclusion

Our results predicted active components and potential targets of AMC for the application to renal fibrosis from a holistic perspective, as well as provided valuable direction for further research of AMC and improved comprehension of renal fibrosis pathogenesis.

Huangkui Capsule Ameliorates Renal Fibrosis in a Unilateral Ureteral Obstruction Mouse Model Through TRPC6 Dependent Signaling Pathways

Renal fibrosis is the final common pathological manifestation of almost all progressive chronic kidney diseases (CKD). Transient receptor potential canonical (TRPC) channels, especially TRPC3/6, were proposed to be essential therapeutic targets for kidney injury. Huangkui capsule (HKC), an important adjuvant therapy for CKD, showed superior efficacy for CKD at stages 1–2 in clinical practice. However, its anti-fibrotic effect and the underlying mechanisms remain to be investigated. In the present study, we evaluated the efficacy of HKC on renal fibrosis in a mouse model of unilateral ureteral obstruction (UUO) and explored the potential underlying mechanism. Administration of HKC by intragastric gavage dose-dependently suppressed UUO-induced kidney injury and tubulointerstitial fibrosis. Similarly, HKC suppressed the expression level of α-smooth muscle actin (α-SMA), increased the expression of E-cadherin, and suppressed the mRNA expression of a plethora of proinflammatory mediators that are necessary for the progression of renal fibrosis. Mechanistically, HKC suppressed both canonical and non-canonical TGF-β signaling pathways in UUO mice as well as the TRPC6/calcineurin A (CnA)/nuclear factor of activated T cells (NFAT) signaling axis. In addition, TRPC6 knockout mice and HKC treated wild type mice displayed comparable protection on UUO-triggered kidney tubulointerstitial injury, interstitial fibrosis, and α-SMA expression. More importantly, HKC had no additional protective effect on UUO-triggered kidney tubulointerstitial injury and interstitial fibrosis in TRPC6 knockout mouse. Further investigation demonstrated that HKC could directly suppress TRPC3/6 channel activities. Considered together, these data demonstrated that the protective effect of HKC on renal injury and interstitial fibrosis is dependent on TRPC6, possibly through direct inhibition of TRPC6 channel activity and indirect suppression of TRPC6 expression.

Anti-Inflammatory Effects of Ribes diacanthum Pall Mediated via Regulation of Nrf2/HO-1 and NF-κB Signaling Pathways in LPS-Stimulated RAW 264.7 Macrophages and a TPA-Induced Dermatitis Animal Model

Ribes diacanthum Pall (RDP) is a Mongolian traditional medicine used to treat renal inflammation. In the present study, we initially investigated the anti-inflammatory effects and mechanisms of action of ethylacetate extract of RDP (EARDP) in RAW 264.7 macrophages stimulated by lipopolysaccharide (LPS) and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced dermatitis in mice. We demonstrated that EARDP protected against LPS-induced cell death by inhibiting intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) production, as well as the synthesis of pro-inflammatory mediators and cytokines, such as nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β. EARDP inhibited the phosphorylation and degradation of inhibitory κB-α (IκB-α) and the activation of nuclear factor (NF)-κB, indicating that the anti-inflammatory effect of EARDP was mediated via the suppression of NF-κB nuclear translocation. In addition, EARDP induced the heme oxygenase-1 (HO-1) expression and nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2), indicating that EARDP induced HO-1 via the Nrf2 pathway in RAW 264.7 cells. Furthermore, EARDP significantly suppressed the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated RAW 264.7 macrophages. However, ZnPP, a specific inhibitor of HO-1, reversed the EARDP-mediated inhibition of NO and TNF-α production in LPS-stimulated RAW 264.7 macrophages. EARDP blocked the phosphorylation of mitogen-activated protein kinase (MAPK) and Akt in LPS-stimulated RAW 264.7 cells. In the in vivo animal model, EARDP significantly and dose-dependently reduced TPA-induced secretion of TNF-α and IL-6 in mouse ear. Based on these results, EARDP represents a promising natural compound, protective against oxidative stress and inflammatory diseases.

Integrating the Polydopamine Nanosphere/Aptamers Nanoplatform with a DNase-I-Assisted Recycling Amplification Strategy for Simultaneous Detection of MMP-9 and MMP-2 during Renal Interstitial Fibrosis

Matrix metalloproteinase-9 (MMP-9) and matrix metalloproteinase-2 (MMP-2) play important roles in the progression of renal interstitial fibrosis (RIF). There is an increasing demand to construct a novel method for the simultaneous detection of MMP-9 and MMP-2 to monitor the progression of RIF. Herein, a strategy based on the nanoplatform composed of the polydopamine nanosphere and fluorescence-labeled aptamers is developed to simultaneously detect MMP-9 and MMP-2 with DNase-I-assisted recycling signal amplification. In the light of tracing the recovered fluorescence intensity at 520 and 610 nm upon adding MMP-9 and MMP-2, the increased fluorescence intensity is linear to the different concentrations of MMP-9 and MMP-2 with the detection limits of 9.6 and 25.6 pg/mL for MMP-9 and MMP-2, respectively. More intriguingly, the results of unilateral ureteral obstruction mice show that the concentration of MMP-9 in urine is increased with the extension of ligation time while the concentration of MMP-2 is reversed, indicating that the ratio of MMP-9 to MMP-2 could be considered as the potential urinary biomarker to evaluate the progress of RIF and the therapeutic effect of Huangkui capsule on RIF. Therefore, this study provides a paradigmatic strategy for the simultaneous detection of the dual markers of RIF, which is promising for the auxiliary clinical diagnosis and assessment of the prognosis of chronic kidney disease.

Mindin deficiency alleviates renal fibrosis through inhibiting NF-κB and TGF-β/Smad pathways

Renal fibrosis acts as a clinical predictor in patients with chronic kidney disease and is characterized by excessive extracellular matrix (ECM) accumulation. Our previous study suggested that mindin can function as a mediator for liver steatosis pathogenesis. However, the role of mindin in renal fibrosis remains obscure. Here, tumour necrosis factor (TGF)‐β‐treated HK‐2 cells and global mindin knockout mouse were induced with renal ischaemia reperfusion injury (IRI) to test the relationship between mindin and renal fibrosis. In vitro, mindin overexpression promoted p65—the hub subunit of the NF‐κB signalling pathway—translocation from the cytoplasm into the nucleus, resulting in NF‐κB pathway activation in TGF‐β‐treated HK‐2 cells. Meanwhile, mindin activated the TGF‐β/Smad pathway, thereby causing fibrotic‐related protein expression in vitro. Mindin^−/− mice exhibited less kidney lesions than controls, with small renal tubular expansion, inflammatory cell infiltration, as well as collagen accumulation, following renal IRI. Mechanistically, mindin^−/− mice suppressed p65 translocation and deactivated NF‐κB pathway. Simultaneously, mindin disruption inhibited the TGF‐β/Smad pathway, alleviating the expression of ECM‐related proteins. Hence, mindin may be a novel target of renal IRI in the treatment of renal fibrogenesis.

Vascular endothelial growth factor 165 inhibits pro-fibrotic differentiation of stromal cells via the DLL4/Notch4/smad7 pathway

Endometrial fibrosis is the main pathological feature of Asherman’s syndrome (AS), which is the leading cause of uterine infertility. Much is known about the expression of VEGF165 in luminal/glandular epithelial cells and stromal cells of the endometrium in normal menstrual cycles; however, less is known about the role and mechanism of VEGF165 in endometrial fibrosis. Herein, we report that VEGF165 is a key regulator in endometrial stromal cells to inhibit α-SMA and collagen 1 expression. Compared to human control subjects, patients with AS exhibited decreased VEGF165 expression in the endometrium along with increased fibrotic marker expression and collagen production. A fibrotic phenotype was shown in both mice with conditional VEGF reduction and VEGF165-deleted endometrial stromal cells. Exogenous VEGF165 could suppress TGFβ1-induced α-SMA and collagen 1 expression in human primary endometrial stromal cells. However, this beneficial effect was hindered when the expression of smad7 or Notch4 was inhibited or when Notch signaling was blocked, suggesting that smad7 and Notch4 are essential downstream molecules for VEGFA functioning. Overall, our results uncover a clinical targeting strategy for VEGF165 to inhibit pro-fibrotic differentiation of stromal cells by inducing DLL4/Notch4/smad7, which paves the way for AS treatment.

Activation of TRPC6 channels contributes to (+)-conocarpan-induced apoptotic cell death in HK-2 cells

(+)-Conocarpan (CNCP), a neolignan frequently found in many medicinal and edible plants displays a broad spectrum of bioactivity. Here, we demonstrated that CNCP induced apoptotic cell death in human kidney-2 (HK-2) cells in a concentration-dependent manner (IC₅₀ = 19.3 μM) and led to the sustained elevation of intracellular Ca²⁺ ([Ca²⁺]_i). Lower extracellular Ca²⁺ concentrations from 2.3 mM to 0 mM significantly suppressed the CNCP-induced Ca²⁺ response by 69.1%. Moreover, the depletion of intracellular Ca²⁺ stores using thapsigargin normalized CNCP-induced Ca²⁺ release from intracellular Ca²⁺ stores, suggesting that the CNCP-induced Ca²⁺ response involved both extracellular Ca²⁺ influx and Ca²⁺ release from intracellular Ca²⁺ stores. SAR7334, a TRPC3/6/7 channel inhibitor, but neither Pyr3, a selective TRPC3 channel inhibitor, nor Pico145, a TRPC1/4/5 inhibitor, suppressed the CNCP-induced Ca²⁺ response by 57.2% and decreased CNCP-induced cell death by 53.4%, suggesting a critical role for TRPC6 channels in CNCP-induced Ca²⁺ influx and apoptotic cell death. Further electrophysiological recording demonstrated that CNCP directly activated TRPC6 channels by increasing channel open probability with an EC₅₀ value of 6.01 μM. Considered together, these data demonstrate that the direct activation of TRPC6 channels contributes to CNCP-induced apoptotic cell death in HK-2 cells. Our data point out the potential risk of renal toxicity from CNCP if used as a therapeutic agent.