Mesangial cell proliferation is the most basic pathological feature of immunoglobulin A nephropathy (IgAN); however, the specific underlying mechanism and an appropriate therapeutic strategy are yet to be unearthed. This study aimed to investigate the therapeutic effect of triptolide (TP) on IgAN and the mechanism by which TP regulates autophagy and proliferation of mesangial cells through the CARD9/p38 MAPK pathway.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/cpr.13278

Triptolide promotes autophagy to inhibit mesangial cell proliferation in IgA nephropathy via the CARD9/p38 MAPK pathway

Triptolide, a controversial natural compound due to its significant pharmacological activities and multiorgan toxicity, has gained much attention since it was isolated from the traditional Chinese herb Tripterygium wilfordii Hook F. However, in addition to its severe toxicity, triptolide also presents powerful therapeutic potency in the same organs, such as the liver, kidney, and heart, which corresponds to the Chinese medicine theory of You Gu Wu Yun (anti-fire with fire) and deeply interested us. To determine the possible mechanisms involved in the dual role of triptolide, we reviewed related articles about the application of triptolide in both physiological and pathological conditions. Inflammation and oxidative stress are the two main ways triptolide exerts different roles, and the cross-talk between NF-κB and Nrf2 may be one of the mechanisms responsible for the dual role of triptolide and may represent the scientific connotation of You Gu Wu Yun. For the first time, we present a review of the dual role of triptolide in the same organ and propose the possible scientific connotation of the Chinese medicine theory of You Gu Wu Yun, hoping to promote the safe and efficient use of triptolide and other controversial medicines. 

Friend or foe? The dual role of triptolide in the liver, kidney, and heart.

Accumulating clinical evidence showed that Tripterygium hypoglaucum (Lév.) Hutch (THH) is effective against IgA nephropathy (IgAN), but the mechanism is still unclear. This study is to evaluate the renal protective effect and molecular mechanism of THH against IgAN via network pharmacology, molecular docking strategy and experimental validation.Several databases were used for obtaining the active ingredients of THH, the corresponding targets, as well as the IgAN-related genes. The critical active ingredients, functional pathways, and potential for the combination of the hub genes and their corresponding active components were determined through bioinformatics analysis and molecular docking. The IgAN mouse model was treated with celastrol (1 mg/kg/d) for 21 days, and the aggregated IgA1-induced human mesangial cell (HMC) was treated with various concentrations of celastrol (25, 50 or 75 nM) for 48 h. The immunohistochemistry and Western blot techniques were applied to evaluate the protein expression of the predicted target. The cell counting kit 8 (CCK8) was used to detect HMC proliferation.A total of 17 active ingredients from THH were screened, covering 165 IgAN-related targets. The PPI network identified ten hub targets, including PTEN. The binding affinity between the celastrol and PTEN was the highest (-8.69 kJ/mol). The immunohistochemistry showed that celastrol promoted the expression of PTEN in the glomerulus of IgAN mice. Furthermore, the Western blot techniques showed that celastrol significantly elevated the expression of PTEN and inhibited PCNA and Cyclin D1 in vitro and in vivo. The CCK8 assay determined that celastrol decreased HMC proliferation in a concentration-dependent manner.This study suggests that activating PTEN by celastrol may play a pivotal role in THH alleviating IgAN renal injury. 

Network Pharmacology and Experimental Validation to Explore That Celastrol Targeting PTEN is the Potential Mechanism of Tripterygium wilfordii (Lév.) Hutch Against IgA Nephropathy

Purpose Accumulating clinical evidence showed that Tripterygium hypoglaucum (Lév.) Hutch (THH) is effective against IgA nephropathy (IgAN), but the mechanism is still unclear. This study is to evaluate the renal protective effect and molecular mechanism of THH against IgAN via network pharmacology, molecular docking strategy and experimental validation. Methods Several databases were used for obtaining the active ingredients of THH, the corresponding targets, as well as the IgAN-related genes. The critical active ingredients, functional pathways, and potential for the combination of the hub genes and their corresponding active components were determined through bioinformatics analysis and molecular docking. The IgAN mouse model was treated with celastrol (1 mg/kg/d) for 21 days, and the aggregated IgA1-induced human mesangial cell (HMC) was treated with various concentrations of celastrol (25, 50 or 75 nM) for 48 h. The immunohistochemistry and Western blot techniques were applied to evaluate the protein expression of the predicted target. The cell counting kit 8 (CCK8) was used to detect HMC proliferation. Results A total of 17 active ingredients from THH were screened, covering 165 IgAN-related targets. The PPI network identified ten hub targets, including PTEN. The binding affinity between the celastrol and PTEN was the highest (−8.69 kJ/mol). The immunohistochemistry showed that celastrol promoted the expression of PTEN in the glomerulus of IgAN mice. Furthermore, the Western blot techniques showed that celastrol significantly elevated the expression of PTEN and inhibited PCNA and Cyclin D1 in vitro and in vivo. The CCK8 assay determined that celastrol decreased HMC proliferation in a concentration-dependent manner. Conclusion This study suggests that activating PTEN by celastrol may play a pivotal role in THH alleviating IgAN renal injury.

Triptolide (TP) has potential adoption value in the treatment of nephropathy, but its poor water solubility causes toxicity and side effects to various degrees in the kidney, liver, and other organs. In this research, TP-mesoscale nanoparticles (TP-MNPs) were synthesized by the amide
 reaction of poly(lactic-co-glycolic acid) (PLGA) and methoxy polyethylene glycol amine (mPEG-NH2) as drug carrier materials. The structure of TP-MNPs was characterized by 1H NMR, scanning electron microscopy (SEM), and zeta potential using a nanoparticle potential analyzer.
 Liquid chromatography–mass spectrometry (HPLC–MS) was utilized to determine the content of TP in TP-MNPs and calculate the entrapment rate (ER) and drug loading (DL) of TP-MNPs. The cytotoxicity of TP-MNPs was detected by CCK8. Eight mice were enrolled in Blank group (no treatment),
 and the other 24 model group animals were rolled into model group (DM), TP group (TP intervention), and TP-MNP group (TP-MNPs intervention) randomly, with eight mice in each group. The urine protein content, serum albumin (Alb), blood glucose (Glu), creatinine (Cre), total cholesterol (TCHO),
 and triglyceride (TG) contents of mice in various groups after intervention were compared. The results revealed that average diameter of MNPs was (379.6±26.44) nm, that of TP-MNPs was (424.3±56.29) nm, and average zeta potentials of TP, MNPs, and TP-MNPs were (−28.29±3.85)
 mV, (−15.51±1.79) mV, and (−13.45±1.81) mV, respectively. The curve changed with TP concentration. With increasing TP concentration, the ER of TP-MNPs decreased drastically, and the DL demonstrated a drastic upward trend. Furthermore, the cell activities of HK-2,
 NRK-52E, LO2, and AML-12 treated with TP-MNPs were higher versus TP group (P <0.05). Urine protein content, body weight, renal index, serum Glu, TCHO, and TG content in the DM group were markedly superior to Blank group (P <0.001), while urine protein content in TP-MNP
 group was considerably inferior to the DM group (P <0.01). Alb and Cre in the serum of mice in DM group were substantially lower versus Blank group (P <0.01), while those in TP group were lower than Blank group (P <0.05). Alb and Cre in TP-MNP group were superior
 to DM group (P <0.05). In summary, TP-MNPs prepared in this research had ideal biocompatibility, could effectively improve urinary protein, body weight, renal index, and serum biochemical indexes caused by DM, and had a certain therapeutic effect on diabetic nephropathy (DN) mice.

Lu Zhao

Papers

Triptolide promotes autophagy to inhibit mesangial cell proliferation in IgA nephropathy via the CARD9/p38 MAPK pathway