Puerarin Alleviates Lipopolysaccharide-Induced Myocardial Fibrosis by Inhibiting PARP-1 to Prevent HMGB1-Mediated TLR4-NF-κB Signaling Pathway

HMGB1 as an extracellular pro-inflammatory cytokine: Implications for drug-induced organic damage

Drug-induced organic damage encompasses various intricate mechanisms, wherein HMGB1, a non-histone chromosome-binding protein, assumes a significant role as a pivotal hub gene. The regulatory functions of HMGB1 within the nucleus and extracellular milieu are interlinked. HMGB1 exerts a crucial regulatory influence on key biological processes including cell survival, inflammatory regulation, and immune response. HMGB1 can be released extracellularly from the cell during these processes, where it functions as a pro-inflammation cytokine. HMGB1 interacts with multiple cell membrane receptors, primarily Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE), to stimulate immune cells and trigger inflammatory response. The excessive or uncontrolled HMGB1 release leads to heightened inflammatory responses and cellular demise, instigating inflammatory damage or exacerbating inflammation and cellular demise in different diseases. Therefore, a thorough review on the significance of HMGB1 in drug-induced organic damage is highly important for the advancement of pharmaceuticals, ensuring their effectiveness and safety in treating inflammation as well as immune-related diseases. In this review, we initially outline the characteristics and functions of HMGB1, emphasizing their relevance in disease pathology. Then, we comprehensively summarize the prospect of HMGB1 as a promising therapeutic target for treating drug-induced toxicity. Lastly, we discuss major challenges and propose potential avenues for advancing the development of HMGB1-based therapeutics.

Inhibitory Effect of Puerarin on Lipopolysaccharide-triggered Inflammatory Responses of Bovine Kidney Cells

Puerarin (Pue), a flavonoid compound, possesses cytoprotective effects and LPS has been reported to induce renal inflammatory injury in bovine. However, whether Pue inhibits lipopolysaccharide (LPS)-induced inflammatory damage of bovine kidney cells remains unknown. Based on an in vitro model with Madin-Darby bovine kidney (MDBK) cell line, it has found that Pue attenuated LPS-induced damage of MDBK cells, as evidenced by cell viability and lactic dehydrogenase (LDH) release rescued by Pue (P < 0.05). Additionally, the real-time quantitative PCR (qPCR) and enzyme linked immunosorbent assay (ELISA) showed that LPS elevated the levels of pro-inflammatory factors interleukin (IL)-1β, IL-8 and tumor necrosis factor (TNF)-α, which was reversed by pretreatment of Pue (P < 0.05). Besides, Pue reduced the expression of Toll like receptor 4 (TLR4) and phosphorylated nuclear factor kappa B (p-NF-κB) of LPS-exposed MDBK cells (P < 0.05). Collectively, these results showed that Pue suppresses LPS-evoked inflammatory damage of bovine kidney cells, suggesting Pue a potential compound for intervention of bovine inflammation.

The beneficial health effects of puerarin in the treatment of cardiovascular diseases: from mechanisms to therapeutics

Cardiovascular diseases (CVDs) are the leading causes of death globally that seriously threaten human health. Although novel western medicines have continued to be discovered over the past few decades to inhibit the progression of CVDs, new drug research and development for treating CVDs with less side effects and adverse reactions are continuously being desired. Puerarin is a natural product found in a variety of medicinal plants belonging to the flavonoid family with potent biological and pharmacological activities. Abundant research findings in the literature have suggested that puerarin possesses a promising prospect in treating CVDs. In recent years, numerous new molecular mechanisms of puerarin have been explored in experimental and clinical studies, providing new evidence for this plant metabolite to protect against CVDs. This article systematically introduces the history of use, bioavailability, and various dosage forms of puerarin and further summarizes recently published data on the major research advances and their underlying therapeutic mechanisms in treating CVDs. It may provide references for researchers in the fields of pharmacology, natural products, and internal medicine.

Pericardial Delivery of SDF-1α Puerarin Hydrogel Promotes Heart Repair and Electrical Coupling

The stromal-derived factor 1α/chemokine receptor 4 (SDF-1α/CXCR4) axis contributes to myocardial protection after myocardial infarction (MI) by recruiting endogenous stem cells into the ischemic tissue. However, excessive inflammatory macrophages are also recruited simultaneously, aggravating myocardial damage. More seriously, the increased inflammation contributes to abnormal cardiomyocyte electrical coupling, leading to inhomogeneities in ventricular conduction and retarded conduction velocity. It is highly desirable to selectively recruit the stem cells but block the inflammation. In this work, SDF-1α-encapsulated Puerarin (PUE) hydrogel (SDF-1α@PUE) is capable of enhancing endogenous stem cell homing and simultaneously polarizing the recruited monocyte/macrophages into a repairing phenotype. Flow cytometry analysis of the treated heart tissue shows that endogenous bone marrow mesenchymal stem cells, hemopoietic stem cells, and immune cells are recruited while SDF-1α@PUE efficiently polarizes the recruited monocytes/macrophages into the M2 type. These macrophages influence the preservation of connexin 43 (Cx43) expression which modulates intercellular coupling and improves electrical conduction. Furthermore, by taking advantage of the improved "soil", the recruited stem cells mediate an improved cardiac function by preventing deterioration, promoting neovascular architecture, and reducing infarct size. These findings demonstrate a promising therapeutic platform for MI that not only facilitates heart regeneration but also reduces the risk of cardiac arrhythmias.

Effects of puerarin on the intervertebral disc degeneration and biological characteristics of nucleus pulposus cells

CONTEXT

Intervertebral disc degeneration (IDD) is the pathological basis of spinal degenerative diseases. Puerarin (PU) is an isoflavonoid with functions and medicinal properties.

OBJECTIVE

To explore the effect of PU on IDD and its potential mechanism of action.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were divided into sham, IDD, low PU, and high PU groups. Rat nucleus pulposus cells (NPCs) were isolated and divided into control, IL-1β, 100 and 200 μmol/mL PU, TAK-242 (TLR4 inhibitor), or 200 μmol/mL PU + LPS (TLR4 activator) groups. The water content, inflammatory factors, proliferation activity, TLR4/NF-κB pathway activity, apoptosis rate, protein expression of apoptosis, and histology of the extracellular matrix (ECM) were analysed.

RESULTS

In vivo: Compared with the IDD group, disorganization of intervertebral disc tissue was significantly improved, water content (2.80 ± 0.24 mg, 3.91 ± 0.31 mg vs. 2.02 ± 0.21 mg) and expression levels of collagen II and aggrecan were significantly increased, and the levels of inflammatory factors and the expression levels of TLR4, MyD88, and p-p65 were significantly decreased in IDD rats treated with PU. In vitro: Compared with the IL-1β group, the proliferation activity of IL-1β-treated NPCs and the expression of collagen II and aggrecan were significantly increased, while the apoptosis rate, levels of inflammatory factors, and the expression levels of TLR4, MyD88, and p-p65 were significantly decreased in IL-1β-treated NPCs treated with PU. LPS reversed the biological function changes of IL-1β-treated NPCs induced by PU.

CONCLUSIONS

PU can delay the progression of IDD by inhibiting activation of the TLR4/NF-κB pathway.

Puerarin Alleviates Oxidized Oil-Induced Oxidative Injury and Inflammation via Inhibition of the Nrf2/Keap1 and HMGB1/TLR4/MAPK Signaling Pathways: An Investigation in a Chicken Model

SCOPE

Puerarin has possessed a wide range of pharmacological activities. However, little is known about the protective effects of puerarin on the oxidized oil-induced injury. Here, the antioxidant and anti-inflammatory effects of puerarin are described using a chicken model.

METHODS AND RESULTS

A total of 360 broilers are arranged in four treatments. Diets include two types of soybean oil (fresh or oxidized) and two levels of puerarin (0 or 750 mg kg-1 ). Results show that puerarin alleviates oxidized soybean oil-induced hepatic and thymic oxidative injury. This effect is observed by increasing the SOD activity and the expressions of Nrf2 signaling pathway-related genes and reducing the MDA content in the liver and thymus. Moreover, puerarin supplementation decreases the concentrations and mRNA levels of pro-inflammatory factors in the liver and thymus. The potential mechanism responsible for this is the decrease in the mRNA or protein levels of HMGB1, TLR4, MyD88, and p65 in the liver or thymus. Western blotting results indicate that puerarin also decreases the phosphorylation of JNK1/2, ERK1/2, and p38 in the liver and thymus.

CONCLUSION

This study demonstrates puerarin may be a potential nutrient supplement in the treatment of oxidized oil-induced damage, and the Nrf2/Keap1 and HMGB1/TLR4/MAPK signaling pathways might be its important target.

The Redox Protein High-Mobility Group Box 1 in Cell Death and Cancer

Significance: As a redox-sensitive protein, high-mobility group box 1 (HMGB1) is implicated in regulating stress responses to oxidative damage and cell death, which are closely related to the pathology of inflammatory diseases, including cancer. Recent Advances: HMGB1 is a nonhistone nuclear protein that acts as a deoxyribonucleic acid chaperone to control chromosomal structure and function. HMGB1 can also be released into the extracellular space and function as a damage-associated molecular pattern protein during cell death, including during apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis, alkaliptosis, and cuproptosis. Once released, HMGB1 binds to membrane receptors to shape immune and metabolic responses. In addition to subcellular localization, the function and activity of HMGB1 also depend on its redox state and protein posttranslational modifications. Abnormal HMGB1 plays a dual role in tumorigenesis and anticancer therapy (e.g., chemotherapy, radiation therapy, and immunotherapy) depending on the tumor types and stages. Critical Issues: A comprehensive understanding of the role of HMGB1 in cellular redox homeostasis is important for deciphering normal cellular functions and pathological manifestations. In this review, we discuss compartmental-defined roles of HMGB1 in regulating cell death and cancer. Understanding these advances may help us develop potential HMGB1-targeting drugs or approaches to treat oxidative stress-related diseases or pathological conditions. Future Directions: Further studies are required to dissect the mechanism by which HMGB1 maintains redox homeostasis under different stress conditions. A multidisciplinary effort is also required to evaluate the potential applications of precisely targeting the HMGB1 pathway in human health and disease. Antioxid. Redox Signal. 39, 569-590.

18β-Glycyrrhetinic Acid Alleviates P. multocida-Induced Vascular Endothelial Inflammation by PARP1-Mediated NF-κB and HMGB1 Signalling Suppression in PIEC Cells

Background

At present, the treatment and prevention of Pasteurella multocida infections in pigs mainly rely on antibiotics and vaccines, but inflammatory injury cannot be eliminated. The compound 18β-glycyrrhetinic acid (GA), a pentacyclic triterpenoid extracted from Glycyrrhiza glabra L. root (liquorice) and with a chemical structure similar to that of steroidal hormones, has become a research focus because of its anti-inflammatory, antiulcer, antimicrobial, antioxidant, immunomodulatory, hepatoprotective and neuroprotective effects, but its potential for the treatment of vascular endothelial inflammatory injury by P. multocida infections has not been evaluated. This study aimed to investigate the effects and mechanisms of GA intervention in the treatment of vascular endothelial inflammatory injury by P. multocida infections.

Materials and Methods

Putative targets of GA intervention in the treatment of vascular endothelial inflammatory injury by P. multocida infections were identified using network pharmacological screening and molecular docking simulation. The cell viability of PIEC cells was investigated via the CCK-8 assay. The mechanism of GA intervention in the treatment of vascular endothelial inflammatory injury by P. multocida infections were investigated using cell transfection and western blot.

Results

Through network pharmacological screening and molecular docking simulation, this study found that PARP1 may be a core target for GA to exert anti-inflammatory effects. Mechanistically, GA alleviates P. multocida-induced vascular endothelial inflammation by PARP1-mediated NF-κB and HMGB1 signalling suppression.

Conclusion

These findings, for the first time, demonstrate the potential therapeutic relationship among GA, PARP1 and inflammatory injury, providing a candidate drug, therapeutic targets and explanation for treating vascular endothelial inflammatory injury caused by P. multocida infection.

Trained immunity in monocyte/macrophage: Novel mechanism of phytochemicals in the treatment of atherosclerotic cardiovascular disease

Atherosclerosis (AS) is the pathology of atherosclerotic cardiovascular diseases (ASCVD), characterized by persistent chronic inflammation in the vessel wall, in which monocytes/macrophages play a key role. It has been reported that innate immune system cells can assume a persistent proinflammatory state after short stimulation with endogenous atherogenic stimuli. The pathogenesis of AS can be influenced by this persistent hyperactivation of the innate immune system, which is termed trained immunity. Trained immunity has also been implicated as a key pathological mechanism, leading to persistent chronic inflammation in AS. Trained immunity is mediated via epigenetic and metabolic reprogramming and occurs in mature innate immune cells and their bone marrow progenitors. Natural products are promising candidates for novel pharmacological agents that can be used to prevent or treat cardiovascular diseases (CVD). A variety of natural products and agents exhibiting antiatherosclerotic abilities have been reported to potentially interfere with the pharmacological targets of trained immunity. This review describes in as much detail as possible the mechanisms involved in trained immunity and how phytochemicals of this process inhibit AS by affecting trained monocytes/macrophages.

Activation of the NLRP3 inflammasome by HMGB1 through inhibition of the Nrf2/HO-1 pathway promotes bleomycin-induced pulmonary fibrosis after acute lung injury in rats

OBJECTIVE

Acute lung injury (ALI) is a common complication of critical diseases with high morbidity and mortality. This study explored the regulatory role and mechanism of high mobility histone box 1 protein (HMGB1) on pulmonary fibrosis (PF) after ALI in rats through nucleotide oligomerization domain-like receptor protein-3 (NLRP3) inflammasome.

METHODS

PF rat models after ALI were established by induction of bleomycin. Degree of fibrosis was assessed by Masson staining and Ashcroft scoring. Hydroxyproline (Hyp) contents in lung tissues and rat lung tissue morphology were detected by enzyme-linked-immunosorbent serologic assay (ELISA) and hematoxylin and eosin staining. The levels of NLRP3, major proteins of NLRP3 inflammasome (NLRP3/ASC/caspase-1), and downstream inflammatory cytokines interleukin (IL)-1 and IL-18 were determined using immunohistochemistry, Western blotting analysis, and ELISA. The nuclear/cytoplasmic nuclear factor erythroid 2-related factor 2 (Nrf2) levels and HO-1 levels were measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting analysis. Rats was injected with lentivirus carrying short hairpin (sh)-HMGB1 and zinc protoporphyria (ZNPP) (HO-1 inhibitor) to assess the effects of HMGB1 and HO-1 on PF and NLRP3 inflammasome activation.

RESULTS

Bleomycin induced PF after ALI in rats, manifested as patchy fibrosis, atelectasis, and excessive expansion, and increased Aschcroft score and Hyp content. Bleomycin treatment enhanced levels of NLRP3, ASC, caspase-1, IL-1, and IL-18 in rat lung tissues, which promoted activation of NLRP3 inflammasome. HMGB1 was up-regulated in bleomycin-induced rats. HMGB1 knockdown partially reversed NLRP3 inflammasome activation and PF progression. HMGB1 knockdown promoted Nrf2 nuclear translocation and up-regulated HO-1. Suppression of HO-1 partially reversed inhibition of HMGB1 knockdown on NLRP3 inflammasome activation and PF.

CONCLUSION

HMGB1 can activate NLRP3 inflammasomes and promote PF by inhibiting the Nrf2/HO-1 pathway.

Pharmacological Activity, Pharmacokinetics, and Clinical Research Progress of Puerarin

As a kind of medicine and food homologous plant, kudzu root (Pueraria lobata (Willd.) Ohwi) is called an "official medicine" in Chinese folk medicine. Puerarin is the main active component extracted from kudzu root, and its structural formula is 8-β-D-grapes pyranose-4, 7-dihydroxy isoflavone, with a white needle crystal; it is slightly soluble in water, and its aqueous solution is colorless or light yellow. Puerarin is a natural antioxidant with high health value and has a series of biological activities such as antioxidation, anti-inflammation, anti-tumor effects, immunity improvement, and cardio-cerebrovascular and nerve cell protection. In particular, for the past few years, it has also been extensively used in clinical study. This review focuses on the antioxidant activity of puerarin, the therapy of diverse types of inflammatory diseases, various new drug delivery systems of puerarin, the "structure-activity relationship" of puerarin and its derivatives, and pharmacokinetic and clinical studies, which can provide a new perspective for the puerarin-related drug research and development, clinical application, and further development and utilization.

Puerarin ameliorates myocardial remodeling of spontaneously hypertensive rats through inhibiting TRPC6-CaN-NFATc3 pathway

Puerarin (Pue) has been widely used in the treatment of hypertension and cardiovascular diseases, but the basic mechanism of Pue on myocardial remodeling (MR) of hypertension is not clear. The purpose of this study was to investigate the effect and mechanism of Pue on MR and provide the basis for the clinical application. Thirty male spontaneously hypertensive rats (SHR) and six male Wistar Kyoto rats (WKY) aged 3 months were used in this study, SHR rats were randomly divided into 5 groups, Pue (40 or 80 mg/kg/d, ip) and telmisartan (TELMI) (30 mg/kg/d, ig) were administrated for 12 weeks. We used Echocardiography to detect the cardiac function. Morphology and structure of myocardium were observed. H9C2 cells were subjected to 1 μM Ang Ⅱ in vitro, 100 μM Pue, 0.5 μM Calmodulin-dependent calcineurin (CaN) inhibitor Cyclosporin A (CsA) and 1 μM specific transient receptor potential channel 6 (TRPC6) inhibitor SAR7334 were used in H9C2 cells. Long-term administration of Pue could significantly improve cardiac function, improve morphology and structure of myocardium in vivo. Pue could reduce MR related proteins expression (ACTC1, TGF-β1, CTGF, β-MHC and BNP), attenuate ROS, restore MMP and decrease Ca²⁺-overload in vitro. Further study indicated that Pue could decrease TRPC6 expression and inhibit nuclear factor of activated T cells 3 (NFATc3) nuclear translocation in vitro. These results suggested that puerarin could ameliorate myocardial remodeling through inhibiting TRPC6-CaN-NFATc3 in spontaneously hypertensive rats.

Exosomes from Bone Marrow Mesenchymal Stem Cells with Overexpressed Nrf2 Inhibit Cardiac Fibrosis in Rats with Atrial Fibrillation

Background

Even though nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling has been associated with the pathogenesis of multiple heart conditions, data on roles of Nrf2 within atrial fibrillation (AF) still remain scant. The present investigation had the aim of analyzing Nrf2-overexpressing role/s upon bone mesenchymal stem cell- (BMSC-) derived exosomes in rats with AF.

Methods

Exosomes were collected from control or Nrf2 lentivirus-transduced BMSCs and then injected into rats with AF through the tail vein. AF duration was observed using electrocardiography. Immunohistochemical staining was then employed for assessing Nrf2, HO-1, α-SMA, collagen I, or TGF-β1 expression profiles within atrial myocardium tissues. Conversely, Masson staining was utilized to evaluate atrial fibrosis whereas apoptosis within myocardia was evaluated through TUNEL assays. In addition, TNF-α, IL-1β, IL-4, or IL-10 serum expression was assessed through ELISA.

Results

Results of the current study showed significant downregulation of Nrf2/HO-1 within AF rat myocardia. It was found that injection of the control or Lv-Nrf2 exosomes significantly alleviated and lowered AF timespans together with reducing cardiomyocyte apoptosis. Moreover, injection of Lv-Nrf2 exosomes essentially lowered AF-driven atrial fibrosis and also inhibited inflammatory responses in the rats with AF.

Conclusion

Delivery of BMSC-derived exosomes using overexpressed Nrf2 inhibited AF-induced arrhythmias, myocardial fibrosis, apoptosis, and inflammation via Nrf2/HO-1 pathway triggering.

CCCTC-binding factor-mediated microRNA-340-5p suppression aggravates myocardial injury in rats with severe acute pancreatitis through activation of the HMGB1/TLR4 axis

BACKGROUND

Severe acute pancreatitis (SAP) is a life-threatening disorder associated with multisystem organ failure. This study aimed to investigate the function of high mobility group box 1 (HMGB1) in SAP-induced myocardial injury.

METHODS

A rat model with SAP was induced. The pathological changes in rat pancreatic and cardiac tissues were examined by HE staining. Cardiomyocyte apoptosis in rat cardiac tissues, and the serum levels of myocardial injury markers and pro-inflammatory cytokines were examined. Rat primary cardiomyocytes were treated with H₂O₂ for in vitro experiments. The regulatory molecules of HMGB1 were predicted by bioinformatics analysis. Altered expression of HMGB1, microRNA (miR)-340-5p and CCCTC-binding factor (CTCF) was introduced in rats or cells to investigate their roles in myocardial injury.

RESULTS

CTCF and HMGB1 were highly expressed but miR-340-5p was poorly expressed in cardiac tissues of rats with SAP. HMGB1 silencing reduced toll-like receptor 4 (TLR4) expression to promote proliferation and reduce apoptosis of H₂O₂-treated cardiomyocytes. miR-340-5p targeted HMGB1 mRNA, while CTCF suppressed miR-340-5p transcription. CTCF upregulation or miR-340-5p downregulation blocked the effects of HMGB1 silencing on cardiomyocytes. In vivo, CTCF silencing alleviated injury in rat pancreatic and cardiac tissues and reduced the expression of creatine kinase-MB (CK-MB), lactic dehydrogenase, interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) in rat serum. But further overexpression of HMGB1 or inhibition of miR-340-5p aggravated the symptoms in rats.

CONCLUSION

This study demonstrated that CTCF reduces transcription of miR-340-5p to promote HMGB1 expression, which activates TLR4 expression and promotes myocardial injury in rats with SAP.

The mechanism of HMGB1 secretion and release

High mobility group box 1 (HMGB1) is a nonhistone nuclear protein that has multiple functions according to its subcellular location. In the nucleus, HMGB1 is a DNA chaperone that maintains the structure and function of chromosomes. In the cytoplasm, HMGB1 can promote autophagy by binding to BECN1 protein. After its active secretion or passive release, extracellular HMGB1 usually acts as a damage-associated molecular pattern (DAMP) molecule, regulating inflammation and immune responses through different receptors or direct uptake. The secretion and release of HMGB1 is fine-tuned by a variety of factors, including its posttranslational modification (e.g., acetylation, ADP-ribosylation, phosphorylation, and methylation) and the molecular machinery of cell death (e.g., apoptosis, pyroptosis, necroptosis, alkaliptosis, and ferroptosis). In this minireview, we introduce the basic structure and function of HMGB1 and focus on the regulatory mechanism of HMGB1 secretion and release. Understanding these topics may help us develop new HMGB1-targeted drugs for various conditions, especially inflammatory diseases and tissue damage.

A nuclear protein that gets released after cell death or is actively secreted by immune cells offers a promising therapeutic target for treating diseases linked to excessive inflammation. Daolin Tang from the University of Texas Southwestern Medical Center in Dallas, USA, and colleagues review how cellular stresses can trigger the accumulation of HMGB1, a type of alarm signal protein that promotes the recruitment and activation of inflammation-promoting immune cells. The researchers discuss various mechanisms that drive both passive and active release of HMGB1 into the space around cells. These processes, which include enzymatic modifications of the HMGB1 protein, cell–cell interactions and molecular pathways of cell death, could be targeted by drugs to lessen tissue damage and inflammatory disease caused by HMGB1-induced immune responses

Dexmedetomidine Promotes Lipopolysaccharide-Induced Differentiation of Cardiac Fibroblasts and Collagen I/III Synthesis through α2A Adrenoreceptor-Mediated Activation of the PKC-p38-Smad2/3 Signaling Pathway in Mice

Dexmedetomidine (DEX), a selective α₂ adrenergic receptor (AR) agonist, is commonly used as a sedative drug during critical illness. In the present study, we explored a novel accelerative effect of DEX on cardiac fibroblast (CF) differentiation mediated by LPS and clarified its potential mechanism. LPS apparently increased the expression of α-SMA and collagen I/III and the phosphorylation of p38 and Smad-3 in the CFs of mice. These effects were significantly enhanced by DEX through increasing α_2A-AR expression in CFs after LPS stimulation. The CFs from α_2A-AR knockout mice were markedly less sensitive to DEX treatment than those of wild-type mice. Inhibition of protein kinase C (PKC) abolished the enhanced effects of DEX on LPS-induced differentiation of CFs. We also found that the α-SMA level in the second-passage CFs was much higher than that in the nonpassage and first-passage CFs. However, after LPS stimulation, the TNF-α released from the nonpassage CFs was much higher than that in the first- and second-passage CFs. DEX had no effect on LPS-induced release of TNF-α and IL-6 from CFs. Further investigation indicated that DEX promoted cardiac fibrosis and collagen I/III synthesis in mice exposed to LPS for four weeks. Our results demonstrated that DEX effectively accelerated LPS-induced differentiation of CFs to myofibroblasts through the PKC-p38-Smad2/3 signaling pathway by activating α_2A-AR.

Puerarin Alleviates UUO-Induced Inflammation and Fibrosis by Regulating the NF-κB P65/STAT3 and TGFβ1/Smads Signaling Pathways

Purpose

Puerarin (PR), a Chinese medicine rich in natural components, has been reported to display anti-fibrotic, antioxidant, anti-inflammatory and immunomodulatory properties. However, the protective mechanism of PR against unilateral ureteral obstruction (UUO)-mediated renal injury is not fully clarified. Therefore, the aim of this study was to investigate the effects of PR on UUO mice and its possible mechanisms.

Methods

A total of 32 C57BL/6 mice were divided randomly into four groups (n=8): i) sham-operated group (Sham); ii) UUO group (UUO); iii) UUO + PR 50 mg/kg/day (UUO + PRL); and iv) UUO + PR 100 mg/kg/day (UUO + PRH). Continuous gavage administration for 14 days starting one week postoperatively, while the mice in Sham and UUO groups were given equal amounts of vehicle by the same means. All mice were then sacrificed and serum, 24-hour urine and tissue specimens were collected for renal function, histopathology, Western blot, immunohistochemistry.

Results

Renal function and histopathology revealed that PR improved UUO-mediated renal dysfunction and partially reversed tubular injury and tubulointerstitial fibrosis. Additionally, according to the results of Western blot and immunohistochemistry, PR inhibited the expression of inflammatory factors including IL-1β, IL-6, MCP-1 and ECM-related proteins including α-SMA, COL I and VIM. More importantly, the expression of fibrotic pathways TGF-β1, Smad3, p-Smad3 and inflammatory pathways NF-κB p65, NF-κB p-p65, STAT3, p-STAT3 were inhibited to various extents under the PR treatment, while Smad7 was upregulated.

Conclusion

These findings indicate that PR may inhibit the recruitment of inflammatory factors and extracellular matrix (ECM) deposition through the regulation of the NF-κB p65/STAT3 and TGFβ1/Smads pathways, which alleviates the UUO-induced inflammatory and fibrotic response, thereby reversing renal injury.

Puerarin Ameliorates Caerulein-Induced Chronic Pancreatitis via Inhibition of MAPK Signaling Pathway

Pancreatic fibrosis is one of the most important pathological features of chronic pancreatitis (CP), and pancreatic stellate cells (PSCs) are considered to be the key cells. Puerarin is the most important flavonoid active component in Chinese herb Radix Puerariae, and it exhibited anti-fibrotic effect in various fibrous diseases recently. However, the impact and molecular mechanism of puerarin on CP and pancreatic fibrosis remain unknown. This study systematically investigated the effect of puerarin on CP and pancreatic fibrosis in vivo and in vitro. H&E staining, Sirius Red staining, qRT-PCR and Western blotting analysis of fibrosis and inflammation related genes of pancreatic tissues showed that puerarin notably ameliorated pancreatic atrophy, inflammation and fibrosis in a model of caerulein-induced murine CP. Western blotting analysis of pancreatic tissues showed the phosphorylation level of MAPK family proteins (JNK1/2, ERK1/2 and p38 MAPK) significantly increased after modeling of cerulein, while puerarin could inhibit their phosphorylation levels to a certain extent. We found that puerarin exerted a marked inhibition on the proliferation, migration and activation of PSCs, determined by CCK-8 assay, transwell migration assay, scratch wound-healing assay and expression levels of α-SMA, Fibronectin, Col1α1 and GFAP. Western blotting result demonstrated that puerarin markedly inhibited the phosphorylation of MAPK family proteins (JNK1/2, ERK1/2 and p38 MAPK) of PSCs in a dose-dependent manner whether or not stimulated by platelet-activating factor. In conclusion, the present study showed that puerarin could be a potential therapeutic candidate in the treatment of CP, and the MAPK pathway might be its important target.

Poly(ADP-Ribose) Polymerase 1 Promotes Inflammation and Fibrosis in a Mouse Model of Chronic Pancreatitis

Chronic pancreatitis (CP) is an inflammatory disease of the pancreas characterized by ductal obstructions, tissue fibrosis, atrophy and exocrine and endocrine pancreatic insufficiency. However, our understanding is very limited concerning the disease’s progression from a single acute inflammation, via recurrent acute pancreatitis (AP) and early CP, to the late stage CP. Poly(ADP-ribose) polymerase 1 (PARP1) is a DNA damage sensor enzyme activated mostly by oxidative DNA damage. As a co-activator of inflammatory transcription factors, PARP1 is a central mediator of the inflammatory response and it has also been implicated in acute pancreatitis. Here, we set out to investigate whether PARP1 contributed to the pathogenesis of CP. We found that the clinically used PARP inhibitor olaparib (OLA) had protective effects in a murine model of CP induced by multiple cerulein injections. OLA reduced pancreas atrophy and expression of the inflammatory mediators TNFα and interleukin-6 (IL-6), both in the pancreas and in the lungs. Moreover, there was significantly less fibrosis (Masson’s trichrome staining) in the pancreatic sections of OLA-treated mice compared to the cerulein-only group. mRNA expression of the fibrosis markers TGFβ, smooth muscle actin (SMA), and collagen-1 were markedly reduced by OLA. CP was also induced in PARP1 knockout (KO) mice and their wild-type (WT) counterparts. Inflammation and fibrosis markers showed lower expression in the KO compared to the WT mice. Moreover, reduced granulocyte infiltration (tissue myeloperoxidase activity) and a lower elevation of serum amylase and lipase activity could also be detected in the KO mice. Furthermore, primary acinar cells isolated from KO mice were also protected from cerulein-induced toxicity compared to WT cells. In summary, our data suggest that PARP inhibitors may be promising candidates for repurposing to treat not only acute but chronic pancreatitis as well.

Toll-like receptor 2 and 4 antagonism for the treatment of experimental autoimmune encephalomyelitis (EAE)-related pain

Neuropathic pain is a major symptom of multiple sclerosis (MS) with up to 92% of patients reporting bodily pain, and 85% reporting pain severe enough to cause functional disability. None of the available therapeutics target MS pain. Toll-like receptors 2 and 4 (TLR2/TLR4) have emerged as targets for treating a wide array of autoimmune disorders, including MS, as well as having demonstrated success at suppressing pain in diverse animal models. The current series of studies tested systemic TLR2/TLR4 antagonists in males and females in a low-dose Myelin oligodendrocyte glycoprotein (MOG) experimental autoimmune encephalomyelitis (EAE) model, with reduced motor dysfunction to allow unconfounded testing of allodynia through 50+ days post-MOG. The data demonstrated that blocking TLR2/TLR4 suppressed EAE-related pain, equally in males and females; upregulation of dorsal spinal cord proinflammatory gene expression for TLR2, TLR4, NLRP3, interleukin-1β, IkBα, TNF-α and interleukin-17; and upregulation of dorsal spinal cord expression of glial immunoreactivity markers. In support of these results, intrathecal interleukin-1 receptor antagonist reversed EAE-induced allodynia, both early and late after EAE induction. In contrast, blocking TLR2/TLR4 did not suppress EAE-induced motor disturbances induced by a higher MOG dose. These data suggest that blocking TLR2/TLR4 prevents the production of proinflammatory factors involved in low dose EAE pathology. Moreover, in this EAE model, TLR2/TLR4 antagonists were highly effective in reducing pain, whereas motor impairment, as seen in high dose MOG EAE, is not affected.