Renal protective effect of Paeoniflorin by inhibition of JAK2/STAT3 signaling pathway in diabetic mice

The mechanisms underlying Chinese medicines to treat inflammation in diabetic kidney disease

ETHNIC PHARMACOLOGICAL RELEVANCE

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease (ESRD), which is a public health problem with a significant economic burden. Serious adverse effects, such as hypotension, hyperkalemia, and genitourinary infections, as well as increasing adverse cardiovascular events, limit the clinical application of available drugs. Plenty of randomized controlled trials(RCTs), meta-analysis(MAs) and systematic reviews(SRs) have demonstrated that many therapies that have been used for a long time in medical practice including Chinese patent medicines(CPMs), Chinese medicine prescriptions, and extracts are effective in alleviating DKD, but the mechanisms by which they work are still unknown. Currently, targeting inflammation is a central strategy in DKD drug development. In addition, many experimental studies have identified many Chinese medicine prescriptions, medicinal herbs and extracts that have the potential to alleviate DKD. And part of the mechanisms by which they work have been uncovered.

AIM OF THIS REVIEW

This review aims to summarize therapies that have been proven effective by RCTs, MAs and SRs, including CPMs, Chinese medicine prescriptions, and extracts. This review also focuses on the efficiency and potential targets of Chinese medicine prescriptions, medicinal herbs and extracts discovered in experimental studies in improving immune inflammation in DKD.

METHODS

We searched for relevant scientific articles in the following databases: PubMed, Google Scholar, and Web of Science. We summarized effective CPMs, Chinese medicine prescriptions, and extracts from RCTs, MAs and SRs. We elaborated the signaling pathways and molecular mechanisms by which Chinese medicine prescriptions, medicinal herbs and extracts alleviate inflammation in DKD according to different experimental studies.

RESULTS

After overviewing plenty of RCTs with the low hierarchy of evidence and MAs and SRs with strong heterogeneity, we still found that CPMs, Chinese medicine prescriptions, and extracts exerted promising protective effects against DKD. However, there is insufficient evidence to prove the safety of Chinese medicines. As for experimental studies, Experiments in vitro and in vivo jointly demonstrated the efficacy of Chinese medicines(Chinese medicine prescriptions, medicinal herbs and extracts) in DKD treatment. Chinese medicines were able to regulate signaling pathways to improve inflammation in DKD, such as toll-like receptors, NLRP3 inflammasome, Nrf2 signaling pathway, AMPK signaling pathway, MAPK signaling pathway, JAK-STAT, and AGE/RAGE.

CONCLUSION

Chinese medicines (Chinese medicine prescriptions, medicinal herbs and extracts) can improve inflammation in DKD. For drugs that are effective in RCTs, the underlying bioactive components or extracts should be identified and isolated. Attention should be given to their safety and pharmacokinetics. Acute, subacute, and subchronic toxicity studies should be designed to determine the magnitude and tolerability of side effects in humans or animals. For drugs that have been proven effective in experimental studies, RCTs should be designed to provide reliable evidence for clinical translation. In a word, Chinese medicines targeting immune inflammation in DKD are a promising direction.

STAT3-induced upregulation of lncRNA TTN-AS1 aggravates podocyte injury in diabetic nephropathy by promoting oxidative stress

Background

Diabetic nephropathy (DN) is the most common microvascular complication of diabetes mellitus (DM), being the second cause of end-stage renal disease globally. Podocyte injury is closely associated with DN developmen. Our study aimed to investigate the role of long non-coding RNA (lncRNA) TTN-AS1 in DN-associated podocyte injury.

Methods

The mouse podocyte cell line (MPC5) and human primary podocytes were stimulated by high glucose (HG; 30 nM glucose) to establish the cellular model of DN. Before HG stimulation, both podocytes were transfected with sh-TTN-AS1#1/2 or pcDNA3.1/STAT3 to evaluate the influence of TTN-AS1 knockdown or STAT3 overexpression on HG-induced podocyte injury. TTN-AS1 and STAT3 expression in both podocytes was examined by RT-qPCR. Cell viability and death were assessed by CCK-8 and LDH release assay. ELISA was adopted for testing IL-6 and TNF-α contents in cell supernatants. The levels of oxidative stress markers (ROS, MDA, SOD, and GSH) in cell supernatants were determined by commercial kits. Western blotting was used for measuring the expression of fibrosis markers (fibronectin and α-SMA and podocyte function markers (podocin and nephrin) in podocytes.

Results

HG stimulation led to decreased cell viability, increased cell death, fibrosis, inflammation, cell dysfunction and oxidative stress in podocytes. However, knockdown of TTN-AS1 ameliorated HG-induced podocyte injury. Mechanically, the transcription factor STAT3 interacted with TTN-AS1 promoter and upregulated TTN-AS1 expression. STAT3 overexpression offset the protective effect of TTN-AS1 silencing on HG-induced podocyte damage.

Conclusion

Overall, STAT3-mediated upregulation of lncRNA TTN-AS1 could exacerbate podocyte injury in DN through suppressing inflammation and oxidative stress.

Genus Paeonia monoterpene glycosides: A systematic review on their pharmacological activities and molecular mechanisms

BACKGROUND

Genus Paeonia, which is the main source of Traditional Chinese Medicine (TCM) Paeoniae Radix Rubra (Chishao in Chinese), Paeoniae Radix Alba (Baishao in Chinese) and Moutan Cortex (Mudanpi in Chinese), is rich in active pharmaceutical ingredient such as monoterpenoid glycosides (MPGs). MPGs from Paeonia have extensive pharmacological effects, but the pharmacological effects and molecular mechanisms of MPGs has not been comprehensively reviewed.

PURPOSE

MPGs compounds are one of the main chemical components of the genus Paeonia, with a wide variety of compounds and strong pharmacological activities, and the structure of the mother nucleus-pinane skeleton is similar to that of a cage. The purpose of this review is to summarize the pharmacological activity and mechanism of action of MPGs from 2012 to 2023, providing reference direction for the development and utilization of Paeonia resources and preclinical research.

METHODS

Keywords and phrases are widely used in database searches, such as PubMed, Web of Science, Google Scholar and X-Mol to search for citations related to the new compounds, extensive pharmacological research and molecular mechanisms of MPGs compounds of genus Paeonia.

RESULTS

Modern research confirms that MPGs are the main compounds in Paeonia that exert pharmacological effects. MPGs with extensive pharmacological characteristics are mainly concentrated in two categories: paeoniflorin derivatives and albiflflorin derivatives among MPGs, which contains 32 compounds. Among them, 5 components including paeoniflorin, albiflorin, oxypaeoniflorin, 6'-O-galloylpaeoniflorin and paeoniflorigenone have been extensively studied, while the other 28 components have only been confirmed to have a certain degree of anti-inflammatory and anticomplementary effects. Studies of pharmacological effects are widely involved in nervous system, endocrine system, digestive system, immune system, etc., and some studies have identified clear mechanisms. MPGs exert pharmacological activity through multilateral mechanisms, including anti-inflammatory, antioxidant, inhibition of cell apoptosis, regulation of brain gut axis, regulation of gut microbiota and downregulation of mitochondrial apoptosis, etc. CONCLUSION: This systematic review delved into the pharmacological effects and related molecular mechanisms of MPGs. However, there are still some compounds in MPGs whose pharmacological effects and pharmacological mechanisms have not been clarified. In addition, extensive clinical randomized trials are needed to verify the efficacy and dosage of MPGs.

Paeoniflorin confers ferroptosis resistance by regulating the gut microbiota and its metabolites in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is closely related to ferroptosis, a new type of cell death that mainly manifests as intracellular iron accumulation and lipid peroxidation. Paeoniflorin (PA) helps to improve impaired glucose tolerance, influences the distribution of the intestinal flora, and induces significant resistance to ferroptosis in several models. In this study, we found that PA improved cardiac dysfunction in mice with DCM by alleviating myocardial damage, resisting oxidative stress and ferroptosis, and changing the community composition and structure of the intestinal microbiota. Metabolomics analysis revealed that PA-treated fecal microbiota transplantation affected metabolites in DCM mice. Based on in vivo and in vitro experiments, 11,12-epoxyeicosatrienoic acid (11,12-EET) may serve as a key contributor that mediates the cardioprotective and antiferroptotic effects of PA-treated fecal microbiota transplantation (FMT) in DCM mice.NEW & NOTEWORTHY This study demonstrated for the first time that paeoniflorin (PA) exerts protective effects in diabetic cardiomyopathy mice by alleviating myocardial damage, resisting ferroptosis, and changing the community composition and structure of the intestinal microbiota, and 11,12-epoxyeicosatrienoic acid (11,12-EET) may serve as a key contributor in its therapeutic efficacy.

Advances in oxidative stress in pathogenesis of diabetic kidney disease and efficacy of TCM intervention

Diabetic kidney disease (DKD) is a common complication of diabetes and has become the leading cause of end-stage kidney disease. The pathogenesis of DKD is complicated, and oxidative stress is considered as a core of DKD onset. High glucose can lead to increased production of reactive oxygen species (ROS) via the polyol, PKC, AGE/RAGE and hexosamine pathways, resulting in enhanced oxidative stress response. In this way, pathways such as PI3K/Akt, TGF-β1/p38-MAPK and NF-κB are activated, inducing endothelial cell apoptosis, inflammation, autophagy and fibrosis that cause histologic and functional abnormalities of the kidney and finally result in kidney injury. Presently, the treatment for DKD remains an unresolved issue. Traditional Chinese medicine (TCM) has unique advantages for DKD prevention and treatment attributed to its multi-target, multi-component, and multi-pathway characteristics. Numerous studies have proved that Chinese herbs (e.g., Golden Thread, Kudzuvine Root, Tripterygium glycosides, and Ginseng) and patent medicines (e.g., Shenshuaining Tablet, Compound Rhizoma Coptidis Capsule, and Zishen Tongluo Granule) are effective for DKD treatment. The present review described the role of oxidative stress in DKD pathogenesis and the effect of TCM intervention for DKD prevention and treatment, in an attempt to provide evidence for clinical practice.

Advances in understanding and treating diabetic kidney disease: focus on tubulointerstitial inflammation mechanisms

Diabetic kidney disease (DKD) is a serious complication of diabetes that can lead to end-stage kidney disease. Despite its significant impact, most research has concentrated on the glomerulus, with little attention paid to the tubulointerstitial region, which accounts for the majority of the kidney volume. DKD's tubulointerstitial lesions are characterized by inflammation, fibrosis, and loss of kidney function, and recent studies indicate that these lesions may occur earlier than glomerular lesions. Evidence has shown that inflammatory mechanisms in the tubulointerstitium play a critical role in the development and progression of these lesions. Apart from the renin-angiotensin-aldosterone blockade, Sodium-Glucose Linked Transporter-2(SGLT-2) inhibitors and new types of mineralocorticoid receptor antagonists have emerged as effective ways to treat DKD. Moreover, researchers have proposed potential targeted therapies, such as inhibiting pro-inflammatory cytokines and modulating T cells and macrophages, among others. These therapies have demonstrated promising results in preclinical studies and clinical trials, suggesting their potential to treat DKD-induced tubulointerstitial lesions effectively. Understanding the immune-inflammatory mechanisms underlying DKD-induced tubulointerstitial lesions and developing targeted therapies could significantly improve the treatment and management of DKD. This review summarizes the latest advances in this field, highlighting the importance of focusing on tubulointerstitial inflammation mechanisms to improve DKD outcomes.

Protective effect of paeoniflorin in diabetic nephropathy: A preclinical systematic review revealing the mechanism of action

BACKGROUND

Paeoniflorin (PF), the main active glucoside of Paeonia Lactiflora, has many pharmacological activities, such as inhibition of vasodilation, hypoglycemia, and immunomodulation. Although the current evidence has suggested the therapeutic effects of PF on diabetic nephropathy (DN), its potential mechanism of action is still unclear.

PURPOSE

A systematic review and meta-analysis of the existing literature on paeoniflorin treatment in DN animal models was performed to evaluate the efficacy and mechanism of PF in DN animal models.

METHODS

The risk of bias in each study was judged using the CAMARADES 10-item quality checklist with the number of criteria met varying from 4 / 10 to 7 / 10, with an average of 5.44. From inception to July 2022, We searched eight databases. We used the Cochrane Collaboration's 10-item checklist and RevMan 5.3 software to assess the risk of bias and analyze the data. Three-dimensional dose/time-effect analyses were conducted to examine the dosage/time-response relations between PF and DN.

RESULTS

Nine animal studies were systematically reviewed to evaluate the effectiveness of PF in improving animal models of DN. Meta-analysis data and intergroup comparisons indicated that PF slowed the index of mesangial expansion and tubulointerstitial injury, 24-h urinary protein excretion rate, expression of anti-inflammatory mediators (mRNA of MCP-1, TNF-α, iNOS, and IL-1 β), and expression of immune downstream factors (P-IRAK1, TIRF, P-IRF3, MyD88, and NF-κBp-p65). Furthermore, modeling methods, animal species, treatment duration, thickness of tissue sections during the experiment, and experimental procedures were subjected to subgroup analyses.

CONCLUSION

The present study demonstrated that the reno-protective effects of PF were associated with its inhibition on macrophage infiltration, reduction of inflammatory mediators, and immunomodulatory effects. In conclusion, PF can effectively slow down the progression of DN and hold promise as a protective drug for the treatment of DN. Due to the low bioavailability of PF, further studies on renal histology in animals are urgently needed. We therefore recommend an active exploration of the dose and therapeutic time frame of PF in the clinic and in animals. Moreover, it is suggested to actively explore methods to improve the bioavailability of PF to expand the application of PF in the clinic.

Vinpocetine alleviates intestinal ischemia/reperfusion injury and enhances M2 macrophage polarization in rats: Role of SIRT1/SOCS3/STAT3 signaling pathway

Vinpocetine (Vinpo) is a neuroprotective vasodilator drug. It is an effective therapeutic agent for a variety of cerebrovascular and cognitive disorders. However, its potential protective efficacy on intestinal ischemia/reperfusion (I/R) injury remains elusive. The present study aimed to investigate the effect of Vinpo on intestinal I/R injury and to explore its modulatory effect on sirtuin (SIRT1)/ Suppressor of cytokine signaling (SOCS3)/ Signal Transducer and Activator of Transcription (STAT3) signaling. Twenty-four male Wistar albino rats were randomly allocated into four groups. G1 (sham): rats were subjected to surgical stress without I/R, GII (I/R): rats were subjected to 60 min/2-h I/R, GIII (Vinpo + I/R): rats were pre-treated with Vinpo (20 mg/kg/day, P.O. daily) for 2 weeks before intestinal I/R; GIV (EX527 + Vinpo + I/R): rats received both Vinpo (20 mg/kg/day, P.O.) and EX527 (5 mg/kg, once every 2 days, i.p) for 2 weeks before intestinal I/R. The current results showed that Vinpo improved the intestinal histopathological picture, enhanced M1 to M2 macrophage polarization and alleviated the I/R-induced increase in interleukins (IL-6, IL-1β), tumor necrosis factor (TNF-α), inducible nitric oxide synthase (i-NOS), and nitric oxide (NO). Additionally, Vinpo pretreatment upregulated SIRT1 mRNA expression/protein level and SOCS3 mRNA expression while downregulating P-STAT3 immunoreactivity. The effects of Vinpo were attenuated by the SIRT1 inhibitor EX527. We concluded that Vinpo ameliorated the intestinal I/R injury and enhanced M2 anti-inflammatory macrophage polarization through modulation of SIRT1/SOCS3/STAT3/i-NOS cascade.

JAK/STAT signaling in diabetic kidney disease

Diabetic kidney disease (DKD) is the most important microvascular complication of diabetes and the leading cause of end-stage renal disease (ESRD) worldwide. The Janus kinase/signal transducer and activator of the transcription (JAK/STAT) signaling pathway, which is out of balance in the context of DKD, acts through a range of metabolism-related cytokines and hormones. JAK/STAT is the primary signaling node in the progression of DKD. The latest research on JAK/STAT signaling helps determine the role of this pathway in the factors associated with DKD progression. These factors include the renin-angiotensin system (RAS), fibrosis, immunity, inflammation, aging, autophagy, and EMT. This review epitomizes the progress in understanding the complicated explanation of the etiologies of DKD and the role of the JAK/STAT pathway in the progression of DKD and discusses whether it can be a potential target for treating DKD. It further summarizes the JAK/STAT inhibitors, natural products, and other drugs that are promising for treating DKD and discusses how these inhibitors can alleviate DKD to explore possible potential drugs that will contribute to formulating effective treatment strategies for DKD in the near future.

Rapid identification of chemical components in Xuelian granule by UHPLC-Q-orbitrap-HRMS based on enzyme activity in vitro

BACKGROUND

Xuelian granule (XL), a traditional Chinese medicine (TCM) formula, has been used for the treatment of diabetic nephropathy for a long time as a hospital preparation. Because the active ingredients in the XL that can help to treat diabetic nephropathy are still unclear, which limits the interpretation for its pharmacological mechanism, further development and subsequent study on the material basis of its efficacy.

METHODS

In this study, a screening method based on inhibition activity against aldose reductase (AR) was employed for activity-directed chemical analysis of XL using ultra-high performance liquid chromatography combined with quadrupole-orbitrap high resolution mass spectrometry (UHPLC-Q-orbitrap-HRMS) technique.

RESULTS

A total of 178 compounds, including 46 terpenes, 47 organic acids, 25 flavonoids, 29 phenylethanoid glycosides, and 31 other types, were tentatively identified from XL which might responsible for its AR inhibition activity.

CONCLUSION

This is the first study for a systematic, rapid, and accurate qualitative analysis of XL. This research provides a scientific and experimental basis for further researches on pharmacodynamics material basis and quality control of XL.

The efficacy and safety of Sanqi Qushi Granule in patients with idiopathic membranous nephropathy --protocol of a multicenter, randomized control trial (SQ-AUTUMN)

BACKGROUND

Adult nephropathy is mainly caused by idiopathic membranous nephropathy (IMN). In cases of proteinuria, Modified Ponticelli Regimens (MPR) are often successful. However, it can cause adverse side effects. Oral Sanqi Qushi Granule (SQG) with MPR is effective in patients with IMN. However, whether it can improve the remission rate of IMN and shorten the remission time is unknown. In this trial, SQG with MPR on IMN will be evaluated clinically for its efficacy and safety.

METHODS

We will randomly assign IMN patients who meet the criteria to receives SQG plus cyclical Cyclophosphamide (CTX)/steroids or with placebo plus cyclical CTX/steroids for 6 months. A 12-month follow-up will be conducted on them. Status of remission will be used to assess treatment efficacy.

DISCUSSION

This study aims to appraise whether treatment with SQG plus cyclical CTX/steroids is superior to placebo plus cyclical CTX/steroids in the remission rate of patients with adult IMN. Adverse events of SQG plus MPR will be also evaluated for further researches about Chinese Medicine and MPR on whether it can improve the remission rate of IMN in half a year and shorten the remission time and relieve adverse effects will also be clarified.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200061953 . Registered on 13 July 2022.

Oxidative stress as a culprit in diabetic kidney disease

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease (ESRD), and the prevalence of DKD has increased worldwide during recent years. DKD is associated with poor therapeutic outcomes in most patients, but there is limited understanding of its pathogenesis. This review suggests that oxidative stress interacts with many other factors in causing DKD. Highly active mitochondria and NAD(P)H oxidase are major sources of oxidants, and they significantly affect the risk for DKD. Oxidative stress and inflammation may be considered reciprocal causes of DKD, in that each is a cause and an effect of DKD. Reactive oxygen species (ROS) can act as second messengers in various signaling pathways and as regulators of metabolism, activation, proliferation, differentiation, and apoptosis of immune cells. Epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNAs can modulate oxidative stress. The development of new technologies and identification of new epigenetic mechanisms may provide novel opportunities for the diagnosis and treatment of DKD. Clinical trials demonstrated that novel therapies which reduce oxidative stress can slow the progression of DKD. These therapies include the NRF2 activator bardoxolone methyl, new blood glucose-lowering drugs such as sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists. Future studies should focus on improving early diagnosis and the development of more effective combination treatments for this multifactorial disease.

Paeoniflorin alleviates ischemia/reperfusion induced acute kidney injury by inhibiting Slc7a11-mediated ferroptosis

The pathophysiological mechanism of acute kidney injury (AKI) is complicated, and effective drugs are still lacking. Ferroptosis is a newly discovered regulatory cell death mode characterized by the lethal accumulation of iron and reactive oxygen species-(ROS-)-dependent lipid hydroperoxides. In recent years, ferroptosis has been confirmed to be involved in the progression of AKI. Paeoniflorin (PF) is a traditional Chinese medicine that has protective effects on a variety of kidney diseases including AKI. However, the mechanism by which PF attenuates AKI is unclear. We detected that PF attenuated serum biochemical markers, histological damage, ferroptosis and inflammation in a dose-dependent manner in a mouse AKI model with bilateral renal artery ischemia-reperfusion (IR). Hypoxia-reoxygenation (HR)-induced ferroptosis and inflammation was also inhibited by PF in human renal tubular epithelial cells (HK2). RNA sequence analysis revealed that PF inhibited ferroptosis in HK2 cells by upregulating Slc7a11 in the glutathione pathway after HR treatment. PF failed to further protect cells with specific knockdown of Slc7a11 from ferroptosis under HR conditions. Consequently, these data indicated that PF prevention of ferroptosis in AKI requires dependence on Slc7a11. This study provided a scientific basis for the clinical search for drugs to prevent IR induced AKI.

A natural products solution to diabetic nephropathy therapy

Diabetic nephropathy is one of the most common complications in diabetes. It has been shown to be the leading cause of end-stage renal disease. However, due to their complex pathological mechanisms, effective therapeutic drugs other than angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), which have been used for 20 years, have not been developed so far. Recent studies have shown that diabetic nephropathy is characterized by multiple signalling pathways and multiple targets, including inflammation, apoptosis, pyroptosis, autophagy, oxidative stress, endoplasmic reticulum stress and their interactions. It definitely exacerbates the difficulty of therapy, but at the same time it also brings out the chance for natural products treatment. In the most recent two decades, a large number of natural products have displayed their potential in preclinical studies and a few compounds are under invetigation in clinical trials. Hence, many compounds targeting these singals have been emerged as a comprehensive blueprint for treating strategy of diabetic nephropathy. This review focuses on the cellular and molecular mechanisms of natural prouducts that alleviate this condition, including preclinical studies and clinical trials, which will provide new insights into the treatment of diabetic nephropathy and suggest novel ideas for new drug development.

Immune responses in diabetic nephropathy: Pathogenic mechanisms and therapeutic target

Diabetic nephropathy (DN) is a chronic, inflammatory disease affecting millions of diabetic patients worldwide. DN is associated with proteinuria and progressive slowing of glomerular filtration, which often leads to end-stage kidney diseases. Due to the complexity of this metabolic disorder and lack of clarity about its pathogenesis, it is often more difficult to diagnose and treat than other kidney diseases. Recent studies have highlighted that the immune system can inadvertently contribute to DN pathogenesis. Cells involved in innate and adaptive immune responses can target the kidney due to increased expression of immune-related localization factors. Immune cells then activate a pro-inflammatory response involving the release of autocrine and paracrine factors, which further amplify inflammation and damage the kidney. Consequently, strategies to treat DN by targeting the immune responses are currently under study. In light of the steady rise in DN incidence, this timely review summarizes the latest findings about the role of the immune system in the pathogenesis of DN and discusses promising preclinical and clinical therapies.

The efficacy of a paeoniflorin-sodium alginate-gelatin skin scaffold for the treatment of diabetic wound: An in vivo study in a rat model

OBJECTIVE

To investigate the efficacy of a paeoniflorin-sodium alginate (SA)-gelatin skin scaffold for treating diabetic wound in a rat model.

METHODS

Bioinks were prepared using various percentages of paeoniflorin in the total weight of a solution containing SA and gelatin. Skin scaffolds containing 0%, 1%, 3%, 5%, and 10% paeoniflorin were printed using 3D bioprinting technology, and scaffold microstructure was observed with scanning electron microscopy. Skin scaffolds were then used in rats with diabetic wounds. H&E staining, Masson staining, and immunohistochemical staining for IL-1β and CD31 were performed on days 7 and 14.

RESULTS

All skin scaffolds had a mesh-like structure with uniform pore distribution. Wounds healed well in each group, with the 1% and 3% groups demonstrating the most complete healing. H&E staining showed that skin accessory organs had appeared in each group. On day 7, collagen deposition in the 3% group was higher than in the other groups (P＜0.05), and IL-1β infiltration was lower in the 10% group than in the 3% group (P = 0.002). On day 14, IL-1β infiltration was not significantly different between the 10% and 3% groups (P = 0.078). The CD31 level was higher in the 3% group than in the other groups on days 7 and 14 (P＜0.05).

CONCLUSION

A 3% paeoniflorin-SA-gelatin skin scaffold promoted the healing of diabetic wounds in rats. This scaffold promoted collagen deposition and microvascular regeneration and demonstrated anti-inflammatory properties, suggesting that this scaffold type could be used to treat diabetic wounds.

Inflammatory bowel disease: an overview of Chinese herbal medicine formula-based treatment

Inflammatory bowel disease (IBD) is a chronic recurrent inflammatory disease of the intestine, including Crohn’s disease (CD) and ulcerative colitis (UC), whose etiology and pathogenesis have not been fully understood. Due to its prolonged course and chronic recurrence, IBD imposes a heavy economic burden and psychological stress on patients. Traditional Chinese Herbal Medicine has unique advantages in IBD treatment because of its symptomatic treatment. However, the advantages of the Chinese Herbal Medicine Formula (CHMF) have rarely been discussed. In recent years, many scholars have conducted fundamental studies on CHMF to delay IBD from different perspectives and found that CHMF may help maintain intestinal integrity, reduce inflammation, and decrease oxidative stress, thus playing a positive role in the treatment of IBD. Therefore, this review focuses on the mechanisms associated with CHMF in IBD treatment. CHMF has apparent advantages. In addition to the exact composition and controlled quality of modern drugs, it also has multi-component and multi-target synergistic effects. CHMF has good prospects in the treatment of IBD, but its multi-agent composition and wide range of targets exacerbate the difficulty of studying its treatment of IBD. Future research on CHMF-related mechanisms is needed to achieve better efficacy.

Drug Candidates for Autoimmune Diseases

Most of the immunosuppressive drugs used in the clinic to prevent organ rejection or to treat autoimmune disorders were originally isolated from fungi or bacteria. Therefore, in addition to plants, these are valuable sources for identification of new potent drugs. Many side effects of established drugs limit their usage and make the identification of new immunosuppressants necessary. In this review, we present a comprehensive overview of natural products with potent anti-inflammatory activities that have been tested successfully in different models of chronic inflammatory autoimmune diseases. Some of these candidates already have passed first clinical trials. The anti-inflammatory potency of these natural products was often comparable to those of established drugs, and they could be used at least in addition to standard therapy to reduce their dose to minimize unwanted side effects. A frequent mode of action is the inhibition of classical inflammatory signaling pathways, such as NF-κB, in combination with downregulation of oxidative stress. A drawback for the therapeutic use of those natural products is their moderate bioavailability, which can be optimized by chemical modifications and, in addition, further safety studies are necessary. Altogether, very interesting candidate compounds exist which have the potential to serve as starting points for the development of new immunosuppressive drugs.

The Active Compounds and Therapeutic Target of Tripterygium wilfordii Hook. f. in Attenuating Proteinuria in Diabetic Nephropathy: A Review

Tripterygium wilfordii Hook. f. (TWHF) is a traditional Chinese herbal medicine and widely used to treat diabetic kidney disease in China. Emerging evidences have revealed its ability to attenuate diabetic nephropathy (DN). Tripterygium wilfordii polyglycosides (TWPs), triptolide (TP), and celastrol are predominantly active compounds isolated from TWHF. The effects and molecular mechanisms of TWHF and its active compounds have been investigated in recent years. Currently, it is becoming clearer that the effects of TWHF and its active compounds involve in anti-inflammation, anti-oxidative stress, anti-fibrosis, regulating autophagy, apoptosis, and protecting podocytes effect. This review presents an overview of the current findings related to the effects and mechanisms of TWHF and its active compounds in therapies of DN, thus providing a systematic understanding of the mechanisms and therapeutic targets by which TWHF and its active compounds affect cells and tissues in vitro and in vivo.

Luteolin Attenuates Diabetic Nephropathy through Suppressing Inflammatory Response and Oxidative Stress by Inhibiting STAT3 Pathway

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD). DN has many pathological changes, but tubular injury is considered to be a crucial pathological feature and plays a key role in the progression of DN. Accumulating studies have confirmed that Luteolin (3,4,5,7-tetrahydroxyflavone, Lut) possesses anti-inflammatory and antioxidant activities, which may play a role in kidney protection in DN.

OBJECTIVES

This paper described the effects of Lut on appropriated tubular injury in the kidneys of db/db mice and searched the possible mechanisms underlying the kidney protection effect in DN.

METHODS

Twelve-week-old male C57BL/6 J db/db and C57BL/6 J db/m mice were used for the animal experiments. They were organized into the following five groups for the animal experiments: a db/m group (control, n=6); a db/db group(n=8) ; a db/db group receiving Lut (10 mg/kg/day, n=8)treatment by oral gavage; a db/db group receiving stattic (a selective STAT3 inhibitor,50 mg/Kg/day, n=8) treatment by oral gavage and a db/db group receiving both stattic and Lut treatment by oral gavage.

RESULTS

In this study, we found that Lut might ameliorate glomerular sclerosis and interstitial fibrosis in DN mouse models through inhibiting the inflammatory response and oxidative stress. And it might play its biological function mainly through repressing the STAT3 activation.

CONCLUSIONS

Lut attenuates DN mainly via suppression of inflammatory response and oxidative response. STAT3 pathway is the potential target, which ultimately reduces renal fibrosis and delays the progress of DN.

Epigenetics in kidney diseases

Epigenetics examines heritable changes in DNA and its associated proteins except mutations in gene sequence. Epigenetic regulation plays fundamental roles in kidney cell biology through the action of DNA methylation, chromatin modification via epigenetic regulators and non-coding RNA species. Kidney diseases, including acute kidney injury, chronic kidney disease, diabetic kidney disease and renal fibrosis are multistep processes associated with numerous molecular alterations even in individual kidney cells. Epigenetic alterations, including anomalous DNA methylation, aberrant histone alterations and changes of microRNA expression all contribute to kidney pathogenesis. These changes alter the genome-wide epigenetic signatures and disrupt essential pathways that protect renal cells from uncontrolled growth, apoptosis and development of other renal associated syndromes. Molecular changes impact cellular function within kidney cells and its microenvironment to drive and maintain disease phenotype. In this chapter, we briefly summarize epigenetic mechanisms in four kidney diseases including acute kidney injury, chronic kidney disease, diabetic kidney disease and renal fibrosis. We primarily focus on current knowledge about the genome-wide profiling of DNA methylation and histone modification, and epigenetic regulation on specific gene(s) in the pathophysiology of these diseases and the translational potential of identifying new biomarkers and treatment for prevention and therapy. Incorporating epigenomic testing into clinical research is essential to elucidate novel epigenetic biomarkers and develop precision medicine using emerging therapies.

Comparative and phylogenetic analyses of the chloroplast genomes of species of Paeoniaceae

Plants belonging to family Paeoniaceae are not only economically important ornamental plants but also medicinal plants used as an important source of traditional Chinese medicine. Owing to the complex network evolution and polyploidy evolution of this family, its systematics and taxonomy are controversial and require a detailed investigation. In this study, three complete chloroplast genomes of sect. Paeonia, one of the sections of Paeonia, were sequenced and then analysed together with 16 other published chloroplast genomes of Paeoniaceae species. The total lengths of the chloroplast genomes of these species were 152,153–154,405 bp. A total of 82–87 protein-coding genes, 31–40 tRNA genes and 8 rRNA genes were annotated. Bioinformatics analysis revealed 61–74 simple sequence repeats (SSRs) in the chloroplast genomes, most of which have A/T base preference. Codon usage analysis showed that A/U-ending codons were more positive than C/G-ending codons, and a slight bias in codon usage was observed in these species. A comparative analysis of these 19 species of Paeoniaceae was then conducted. Fourteen highly variable regions were selected for species relationship study. Phylogenetic analysis revealed that the species of sect. Paeonia gathered in one branch and then divided into different small branches. P. lactiflora, P. anomala, P. anomala subsp. veitchii and P. mairei clustered together. P. intermedia was related to P. obovata and P. obovata subsp. willmottiae. P. emodi was the sister to all other species in the sect. Paeonia.

Recent Insights Into the Protective Mechanisms of Paeoniflorin in Neurological, Cardiovascular, and Renal Diseases

ABSTRACT

The monoterpene glycoside paeoniflorin (PF) is the principal active constituent of the traditional Chinese herbal medicines, Radix Paeoniae Alba and Radix Paeoniae Rubra, which have been used for millennia to treat cardiovascular diseases (eg, hypertension, bleeding, and atherosclerosis) and neurological ailments (eg, headaches, vertigo, dementia, and pain). Recent evidence has revealed that PF exerts inhibitory effects on inflammation, fibrosis, and apoptosis by targeting several intracellular signaling cascades. In this review, we address the current knowledge about the pharmacokinetic properties of PF and its molecular mechanisms of action. We also present results from recent preclinical studies supporting the utility of PF for the treatment of pain, cerebral ischemic injury, and neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Moreover, new evidence suggests a general protective role of PF in heart attack, diabetic kidney, and atherosclerosis. Mechanistically, PF exerts multiple anti-inflammatory actions by targeting toll-like receptor-mediated signaling in both parenchymal and immune cells (in particular, macrophages and dendritic cells). A better understanding of the molecular actions of PF may lead to the expansion of its therapeutic uses.

Renoprotective Effect of the Recombinant Anti-IL-6R Fusion Proteins by Inhibiting JAK2/STAT3 Signaling Pathway in Diabetic Nephropathy

Diabetic nephropathy the main reason for end stage renal disease is a common microvascular complication in patients with type 1 and type 2 diabetes. The interleukin-6 (IL-6), acting as a pleiotropic cytokine, play key roles in main autoimmune disorders. The recombinant anti-IL-6R fusion proteins (VHH-0031) constructed and obtained in our lab is a dual target-directed single domain-based fusion protein against the interleukin-6 receptor. This study aims to explore the renoprotective effect of VHH-0031 in diabetic nephropathy. VHH-0031 treatment alleviated renal inflammation, morphologic injury and renal insufficiency in both Goto-Kakizaki rats and STZ-induced Sprague Dawley rats. These renoprotective effects of VHH-0031 are associated with alleviating inflammation and suppression of the JAK2/STAT3 signaling pathway. The mesangial cells treated with VHH-0031 exhibited anti-proliferation, anti-inflammation and inactivation of JAK2/STAT3 pathway under high glucose condition. In conclusion, this study demonstrates that VHH-0031 exhibited a potent protective effect in kidney of diabetic rats and its mechanism may be concerned with the inhibition of the IL-6R/JAK2/STAT3 pathway of glomerular mesangial cells.

Evaluating the Therapeutic Mechanisms of Selected Active Compounds in Cornus Officinalis and Paeonia Lactiflora in Rheumatoid Arthritis via Network Pharmacology Analysis

Cornus officinalis Sieb et. Zucc and Paeonia lactiflora Pall. have exhibited favorable therapeutic effects against rheumatoid arthritis (RA), but the specific mechanisms of their active compounds remain unclear. The aim of this study was to comprehensively analyze the therapeutic mechanisms of selected active compounds in Cornus officinalis (loganin, ursolic acid, and morroniside) and Paeonia lactiflora (paeoniflorin and albiflorin) via network pharmacology. The pharmacological properties of the five active compounds were evaluated and their potential target genes were identified by database screening. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional analysis were performed to determine the enriched molecular pathways associated with the active compounds. Using network pharmacology tools, eight genes (IL1β, VEGFA, STAT3, TP53, IL6, TNF, FOS, and LGALS3) were identified as common targets between RA and the five active compounds. Molecular docking simulation revealed the compound-target relationship between the five active compounds and three selected targets from the eight common ones (LGALS3, STAT3, and VEGFA). The compound-target relationships were subsequently validated via preliminary in vivo experiments in a rat model of collagen-induced arthritis. Rats subjected to collagen-induced arthritis showed increased protein expression of LGALS3, STAT3, and VEGFA in synovial tissues. However, treatment using Cornus officinalis or/and Paeonia lactiflora, as well as their most drug-like active compounds (ursolic acid or/and paeoniflorin, respectively, identified based on pharmacological properties), attenuated the expression of these three targets, as previously predicted. Collectively, network pharmacology allowed the pharmacological and molecular roles of Cornus officinalis and Paeonia lactiflora to be systematically revealed, further establishing them as important candidate drugs in the treatment and management of RA.

Neuritin inhibits astrogliosis to ameliorate diabetic cognitive dysfunction

Earlier, it was shown that reversing the downregulation of neuritin expression in the brain improves central neuropathy in diabetic rats. We investigated the protective mechanism of neuritin in diabetic cognitive dysfunction via astrocytes. Further, the impact of the overexpression of neuritin in the cortex and the hippocampus on diabetic cognitive dysfunction and astrogliosis in type 2 diabetic (db/db) mice was assessed. Antagonists were used to inhibit the JAK2/STAT3 signaling pathway in U-118MG, an astrocyte cell line. Immunofluorescence, Western blotting, and real-time PCR were performed. Neuritin overexpression in the hippocampus of db/db mice significantly ameliorated cognitive dysfunction, hippocampal neuronal impairment, and synaptic plasticity deterioration, and inhibited astrogliosis and the JAK2/STAT3 signaling pathway in the hippocampus. Neuritin suppressed the JAK2/STAT3 signaling pathway to inhibit lipopolysaccharide-induced gliosis in U-118MG cells. It was observed that neuritin regulates the JAK2/STAT3 signaling pathway in astrocytes to inhibit astrogliosis and improve diabetic cognitive dysfunction.

Paeoniflorin protects PC12 cells from oxygen-glucose deprivation/reoxygenation-induced injury via activating JAK2/STAT3 signaling

Ischemic stroke is the most common type of stroke, and it has become a major health issue as it is characterized by high mortality and morbidity rates. Paeoniflorin (PF) is a natural compound and the main active ingredient of Radix Paeoniae. The aim of the present study was to investigate the role of PF in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury of PC12 cells and its association with the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway. An in vitro model of OGD/R injury was established in PC12 cells. Subsequently, Cell Counting Kit-8 assay and ELISA were used to evaluate cell viability and the secretion of inflammatory factors, respectively, in PC12 cells subjected to OGD/R and treated with PF. The levels of oxidative stress indicators and inflammatory factors were measured using corresponding commercial kits. In addition, the apoptosis rate of PC12 cells subjected to OGD/R and treated with PF was determined by flow cytometry, and the expression of apoptosis-related proteins was analyzed by western blotting. Additionally, the expression levels of JAK2/STAT3 pathway-related proteins were also evaluated. The cell viability, levels of oxidative stress, inflammation and apoptosis were also measured in OGD/R-induced PC12 cell injury models following co-treatment of cells with PF and FLLL32, a specific inhibitor of JAK2/STAT3 signaling. Cell viability was reduced, while oxidative stress and inflammation were increased after OGD/R-induced injury. However, the treatment of cells with PF significantly enhanced cell viability, and alleviated oxidative stress, inflammation and apoptosis of OGD/R-treated PC12 cells. Furthermore, PF activated the JAK2/STAT3 signaling pathway. Following FLLL32 intervention, the effects of PF on oxidative stress, inflammation and apoptosis of OGD/R-treated PC12 cells were reversed. In conclusion, the findings of the present study suggested that PF may protect PC12 cells from OGD/R-induced injury via activating the JAK2/STAT3 signaling pathway, thus providing novel insight into the mechanism through which PF may alleviate ischemic stroke and indicating a potential strategy for ischemic stroke treatment.

Nifuroxazide improves insulin secretion and attenuates high glucose-induced inflammation and apoptosis in INS-1 cells

Inflammation and oxidative stress are important factors that cause islet β-cell dysfunction. STAT3 is not only a major factor in cell proliferation and differentiation, but also plays an important role in mediating inflammation. As a potent inhibitor of STAT3, the effect of Nifuroxazide (Nifu) on pancreatic islet cells in a high glucose environment has not been reported. In the present study, we used high concentration glucose-induced INS-1 cells to examine the effects of Nifu on high glucose-induced cell function by glucose-stimulated insulin secretion (GSIS). The effects of Nifu on high glucose-induced oxidative stress were recorded by oxidative factors and antioxidant factors. Simultaneously, the effect of Nifu on the inflammatory response, apoptosis, and STAT3/SOCS3 signal pathway were validated by quantitative real-time PCR (qRT-PCR) and Western blot. Our study indicated that Nifu significantly improved cell vitality and insulin secretion of INS-1 cells induced by high glucose. We found Nifu significantly inhibited pro-oxidative factors (ROS, MDA) and promoted anti-oxidative factors (SOD, GSH-PX, CAT). Meanwhile, qRT-PCR and Western blot results showed that inflammatory and apoptosis factors were remarkably inhibited by Nifu. Further research indicated that Nifu clearly suppressed the activation of the STAT3/SOCS3 signaling pathway. In conclusion, Nifu can significantly improve the insulin secretion function, protect oxidative stress injury, and reduce inflammatory response and apoptosis in high glucose-induced INS-1 cells. Therefore, Nifu has a new positive effect on maintaining the normal function of pancreatic islet cells in a high glucose environment and provides new drug candidates for the treatment and prevention of diabetes.

Inducing Apoptosis and Suppressing Inflammatory Reactions in Synovial Fibroblasts are Two Important Ways for Guizhi-Shaoyao-Zhimu Decoction Against Rheumatoid Arthritis

Background and Objectives

Guizhi-Shaoyao-Zhimu decoction (GSZD) is often applied to control rheumatoid arthritis (RA), gout, osteoarthritis, etc. In this study, bioinformatic analysis and experimental verification were used to uncover the integral mechanism profile of GSZD against RA.

Materials and Methods

The chemical compositions of GSZD were identified by UPLC-QTOF-MS/MS. MH7A cell model was established to screen active compounds in GSZD, and potential targets of these compounds were predicted through online database retrieval. The differential expression genes (DEGs) in synovial tissue of RA patients and normal controls were retrieved from the GEO database. DEGs and the predicated compounds targets were overlapped, and the overlapped genes were subsequently enriched by GO and KEGG analysis. The pathways with significant enrichments were further experimentally verified.

Results

A total of 19 constituents were identified from GSZD, and 11 compounds showed obviously antiproliferative effects on MH7A cells with IC₅₀ < 100 μg/mL. Bioinformatic analysis indicated that IL-1β, IL-6, MAPK8, JAK2, CXCL8, and CASP3 were the main targets of GSZD, and the integral pharmacological mechanisms profile of GSZD might be related to anti-inflammation and proapoptosis. GSZD can promote the loss of mitochondrial membrane potential (MOMP) and induce apoptosis in MH7A cells. Furthermore, in vitro experiments showed GSZD can not only downregulate mRNA expressions of IL-1β (p<0.05), IL-6 (p<0.05), MMPs (p<0.05) and CCL5 (p<0.05) but also inhibit the nuclear transcription of NF-κB. GSZD also reduced the expressions of Bcl-2 (p<0.05), JAK2 (p<0.05), STAT-3 (p<0.05), whereas increase Bax (p<0.05), Caspase-3 (p<0.05) and caspase-9 (p<0.05).

Conclusion

Collectively, inducing synovial fibroblast apoptosis and inhibiting inflammatory response are two important ways for GSZD to RA, and our study proved bioinformatic analysis combined with experimental verification is a feasible method to explore the drug targets and mechanism of actions of TCMs.

Paeoniflorin ameliorates glycemic variability-induced oxidative stress and platelet activation in HUVECs and DM rats

Glycemic variability (GV) plays an important role in the pathogenesis of vascular complications associated with diabetes mellitus (DM). Paeoniflorin is an effective Chinese traditional medicine with anti-inflammatory and immune-regulatory effects. Previous studies implicated the beneficial effects of paeoniflorin in treatment for diabetic complications, such as type 2 diabetic nephropathy and diabetes with myocardial ischemic injury. Current evidence suggests that oxidative stress and platelet activation, as well as their interaction, are potentially associated with GV and involved in the pathogenesis of diabetes-associated vascular complications. This study aimed to explore the effects of paeoniflorin on oxidative stress and platelet activation, using human umbilical vein endothelial cells (HUVECs) cultured with different glucose concentrations, and streptozotocin-induced diabetic rats fed different glycemic index diets. Paeoniflorin treatment effectively improved the morphology and cell viability of HUVECs under glucose fluctuation. Moreover, the platelet aggregation rate, CD62p expression, and reactive oxygen species (ROS) concentration decreased, while glutathione peroxidase (GSH-px) levels increased in paeoniflorin-treated groups. In conclusion, our study found that paeoniflorin ameliorates oxidative stress and platelet activation induced by glycemic variability both in vivo and in vitro, suggesting a novel potential strategy for treatment of diabetic complications.

Glycemic variability (GV) plays an important role in the pathogenesis of vascular complications associated with diabetes mellitus (DM).

Paeoniflorin inhibits IgE-mediated allergic reactions by suppressing the degranulation of mast cells though binding with FcϵRI alpha subunits

Paeoniflorin (PF), a monoterpene glycoside isolated from the aqueous extract of the Chinese herb Radix Paeoniae Alba, has been used for treating various inflammatory diseases. In this study, we aimed to investigate the anti-allergic activities of PF. The anti-anaphylactic activity of PF was investigated using mast cell (MC) degranulation assay as well as Ca²⁺ influx in vitro and skin swelling and extravasation assays in vivo. The results showed that PF inhibited MC degranulation (histamine release from 74.5 ± 4.95 ng/ml to 58.7 ± 6.06 ng/ml) and Ca²⁺ influx challenged by DNP-BSA in vitro. In addition, PF reduced the degree of swelling and Evans blue exudation in mice paws. Furthermore, PF dose-dependently reduced serum inflammatory mediator release in mice sensitized with ovalbumin for 48 h by inhibiting MC degranulation. Molecular docking study revealed that PF bound better with the α subunit of FcϵRI than with the β subunit. SPR revealed that PF had a strong affinity interaction with FcϵRI α subunit and the K_D value was (7.08 ± 0.97) e-6 M. Our findings revealed that PF inhibited anaphylactic responses in vivo and in vitro, and it can be considered a novel FcϵRI inhibitor for preventing MC-related allergic diseases.

Deciphering the multicomponent synergy mechanisms of SiNiSan prescription on irritable bowel syndrome using a bioinformatics/network topology based strategy

BACKGROUND

SiNiSan (SNS) is a traditional Chinese medicine (TCM) prescription that has been widely used in the clinical treatment of irritable bowel syndrome (IBS). However, the underlying active substances and molecular mechanisms remain obscure.

PURPOSE

A bioinformatics/topology based strategy was proposed for identification of the drug targets, therapeutic agents and molecular mechanisms of SiNiSan against irritable bowel syndrome.

MATERIALS AND METHODS

In this work, a bioinformatics/network topology based strategy was employed by integrating ADME filtering, text mining, bioinformatics, network topology, Venn analysis and molecular docking to uncover systematically the multicomponent synergy mechanisms. In vivo experimental validation was executed in a Visceral Hypersensitivity (VHS) rat model.

RESULTS

76 protein targets and 109 active components of SNS were identified. Bioinformatics analysis revealed that 116 disease pathways associated with IBS therapy could be classified into the 19 statistically enriched functional sub-groups. The multi-functional co-synergism of SNS against IBS were predicted, including inflammatory reaction regulation, oxidative-stress depression regulation and hormone and immune regulation. The multi-component synergetic effects were also revealed on the herbal combination of SNS. The hub-bottleneck genes of the protein networks including PTGS2, CALM2, NOS2, SLC6A3 and MAOB, MAOA, CREB1 could become potential drug targets and Paeoniflorin, Naringin, Glycyrrhizic acid may be candidate agents. Experimental results showed that the potential mechanisms of SiNiSan treatment involved in the suppression of activation of Dopaminergic synapse and Amphetamine addiction signaling pathways, which are congruent with the prediction by the systematic approach.

CONCLUSION

The integrative investigation based on bioinformatics/network topology strategy may elaborate the multicomponent synergy mechanisms of SNS against IBS and provide the way out to develop new combination medicines for IBS.

Paeoniflorin Ameliorates Macrophage Infiltration and Activation by Inhibiting the TLR4 Signaling Pathway in Diabetic Nephropathy

Paeoniflorin (PF) is the primary component of total glucosides of paeony (TGP). It exerts multiple effects, including immunoregulatory and anti-inflammatory effects. Our previous study has found that PF has a remarkable renal-protective effect in diabetic mice, but exact mechanism has not been clarified. This study mainly explores whether PF affects macrophage infiltration and activation in diabetic kidney through TLR4 pathway. Thus, this study was conducted to investigate the effect of PF on a streptozotocin (STZ)-induced experimental DN model. The results suggested that the onset and clinical symptoms of DN in mice were remarkably ameliorated after the administration of PF. Moreover, the number of infiltrating macrophages in the mouse kidneys was also markedly decreased. Instead of inhibiting the activation of macrophages directly, PF could influence macrophages by suppressing iNOS expression as well as the production of TNF-α, IL-1β, and MCP-1 both in vivo and in vitro. These effects might be attributable to the inhibition of the TLR4 signaling pathway. The percentage of M1-phenotype cells as well as the mRNA levels of iNOS, TNF-α, IL-1β, and MCP-1 were downregulated when PF-treated polarized macrophages were cultured under conditions of high glucose (HG) levels. In addition, the expression of TLR4, along with that of downstream signaling molecule proteins, was also reduced. Our study has provided new insights into the potential of PF as a promising therapeutic agent for treating DN and has illustrated the underlying mechanism of PF from a new perspective.

A Protective Role of Paeoniflorin in Fluctuant Hyperglycemia-Induced Vascular Endothelial Injuries through Antioxidative and Anti-Inflammatory Effects and Reduction of PKCβ1

Hyperglycemia fluctuation is associated with diabetes mellitus (DM) complications when compared to persistent hyperglycemia. Previous studies have shown that paeoniflorin (PF), through its antiapoptosis, anti-inflammation, and antithrombotic properties, effectively protects against cardiovascular and cerebrovascular disease. However, the mechanism underlying the protection from PF against vascular injuries induced by hyperglycemia fluctuations remains poorly understood. Herein, we investigated the potential protective role of PF on human umbilical vein endothelial cells (HUVECs) subjected to intermittent glucose levels in vitro and in DM rats with fluctuating hyperglycemia in vivo. A remarkable increased apoptosis associated with elevated inflammation, increased oxidative stress, and high protein level of PKCβ1 was induced in HUVECs by intermittently changing glucose for 8 days, and PF recovered those detrimental changes. LY333531, a potent PKCβ1 inhibitor, and metformin manifested similar effects. Additionally, in DM rats with fluctuating hyperglycemia, PF protected against vascular damage as what has been observed in vitro. Taken together, PF attenuates the vascular injury induced by fluctuant hyperglycemia through oxidative stress inhibition, inflammatory reaction reduction, and PKCβ1 protein level repression, suggesting its perspective clinical usage.