Oltipraz attenuates the progression of heart failure in rats through inhibiting oxidative stress and inflammatory response

N-Acetylcysteine Slows Down Cardiac Pathological Remodeling by Inhibiting Cardiac Fibroblast Proliferation and Collagen Synthesis

Objective

By observing the effect of N-acetylcysteine (NAC) on the proliferation and collagen synthesis of rat cardiac fibroblasts (CFs) to explore the effect of NAC on cardiac remodeling (CR).

Methods

In vivo, first, the Sprague Dawley (SD) rat myocardial hypertrophy model was constructed, and the effect of NAC on cardiac structure and function was detected by echocardiography, serological testing, and Masson staining. Western blotting (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression level of antioxidant enzymes, and flow cytometry was used to detect the intracellular reactive oxygen species (ROS) content. In vitro, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and 5-ethynyl-2′-deoxyuridine (EdU) staining were used to detect cell proliferation, and the expression level of the NF-κB signaling pathway was detected.

Results

Compared with the control group, the model group had disordered cardiac structure, reduced cardiac function, and obvious oxidative stress (OS) response. However, after NAC treatment, it could obviously improve the rat cardiac structure and cardiac function and alleviate redox imbalance and cardiology remodeling. At the same time, NAC can inhibit the activation of the NF-κB signaling pathway and reduce the proliferation level of CFs and the amount of ³H proline incorporated.

Conclusions

NAC can inhibit AngII-induced CF proliferation and collagen synthesis through the NF-κB signaling pathway, alleviate the OS response of myocardial tissue, inhibit the fibrosis of myocardial tissue, and thus slow down the pathological remodeling of the heart.

Disruption of STAT6 Signal Promotes Cardiac Fibrosis Through the Mobilization and Transformation of CD11b+ Immature Myeloid Cells

Cardiac fibrosis is an important pathological basis of various cardiovascular diseases. The roles of STAT6 signal in allergy, immune regulation, tumorigenesis, and renal fibrosis have been documented. However, the function and mechanism of STAT6 signal in sympathetic overactivation-induced cardiac fibrosis have not been fully elucidated. This study explores the novel role of STAT6 signal in isoproterenol (ISO)-induced cardiac fibrosis through the regulation of inflammatory response and the differentiation of macrophages from immature myeloid cells. The expression levels of STAT6, β1-adrenergic receptor (β1-AR), and inflammatory factors [interleukin α (IL-1α), IL-6, IL-18, and transforming growth factor β (TGF-β)] in CD11b⁺ myeloid cells were analyzed with a microarray study. The levels of IL-6 and TGF-β1 in the CD11b⁺ myeloid cells-derived macrophages were detected with reverse transcriptase-polymerase chain reaction (RT-PCR). STAT6-knockout (KO) and WT mice were used to establish a murine cardiac fibrosis model by ISO injection. Cardiac fibroblasts were isolated from the hearts of newborn STAT6-KO and WT mice, and STAT6 expression was measured by Western blotting and RT-PCR after ISO stimulation, while α-smooth muscle actin (α-SMA) expression was detected by immunofluorescence and immunohistochemistry staining. Cardiac function and pathological characteristics were examined by echocardiography and immunohistochemistry staining, respectively. Immunohistochemistry staining with anti-CD11b was performed to detect the infiltration of CD11b⁺ myeloid cells in heart tissue. Flow cytometry analysis was used to measure the percentages of CD11b⁺ myeloid cells and CD11b⁺Ly6C⁺ macrophages in the peripheral blood. The results showed that STAT6 was highly expressed in CD11b⁺ myeloid cells located in injured hearts, and STAT6 expression in cardiac fibroblasts was down-regulated after ISO treatment. STAT6 deficiency further aggravated ISO-induced increased expression of α-SMA in cardiac fibroblasts, myocardial fibrosis, and cardiac dysfunction. The activation of ISO/β1-AR signal aggravated cardiac inflammatory infiltration, promoted CD11b⁺ myeloid cell mobilization, and enhanced CD11b⁺Ly6C^+/low macrophage differentiation, which was further exacerbated by STAT6 deficiency. Furthermore, β1-AR mRNA expression significantly increased in splenic CD11b⁺ myeloid cells compared to their bone marrow-derived controls, and STAT6 deficiency promoted β1-AR expression in an MI-induced sensitive cardiac fibrosis mouse model. The spleen-derived CD11b⁺ myeloid cells of STAT6-KO mice produced more IL-1α, IL-18, and TGF-β than their WT counterparts. Taken together, these results suggest that STAT6 signal plays a critical role in ISO-induced β1-AR overactivation and systemic inflammatory cascades, contributing to cardiac fibrogenesis. STAT6 should be a promising cardioprotective target against myocardial fibrosis and heart failure after β1-AR overactivation-induced myocardial injury.

Modulation of Oxidative Stress and Inflammation in the Aged Lacrimal Gland

Inflammation and oxidative stress accompany aging. This study investigated the interplay between oxidative stress and inflammation in the lacrimal gland. C57BL/6 mice were used at 2 to 3, 12, and 24 months of age. Nuclear factor erythroid derived-2-related factor 2 (Nrf2)^-/- and corresponding wild-type mice were used at 2 to 3 and 12 to 13 months of age. A separate group of 15.5 to 17 months of age C57BL/6 mice received a diet containing an Nrf2 inducer (Oltipraz) for 8 weeks. Aged C57BL/6 lacrimal glands showed significantly greater lymphocytic infiltration, higher levels of MHC II, IFN-γ, IL-1β, TNF-α, and cathepsin S (Ctss) mRNA transcripts, and greater nitrotyrosine and 4-hydroxynonenal protein. Young Nrf2^-/- mice showed an increase in IL-1β, IFN-γ, MHC II, and Ctss mRNA transcripts compared with young wild-type mice and greater age-related changes at 12 to 13 months of age. Oltipraz diet significantly decreased nitrotyrosine and 4-hydroxynonenal and decreased the expression of IL-1β and TNF-α mRNA transcripts, while decreasing the frequency of CD45⁺CD4⁺ cells in lacrimal glands and significantly increasing conjunctival goblet cell density compared with a standard diet. The findings provide novel insight into the development of chronic, low-grade inflammation and oxidative stress in age-related dry eye. New therapies targeting oxidative stress pathways will be valuable in treating age-related dry eye.

Oltipraz Prevents High Glucose-Induced Oxidative Stress and Apoptosis in RSC96 Cells through the Nrf2/NQO1 Signalling Pathway

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus (DM). Schwann cell (SC) apoptosis contributes to the occurrence and development of DPN. Effective drugs to prevent SC apoptosis are required to relieve and reverse peripheral nerve injury caused by DM. Oltipraz [4-methyl-5-(2-pyrazinyl)-1,2-dithiole-3-thione], an agonist of nuclear factor erythroid derived-2-related factor 2 (Nrf2), exerts strong effect against oxidative stress in animal models or clinical patients in certain diseases, including heart failure, acute kidney injury, and liver injury. The aim of the present study was to determine the effectiveness of oltipraz in preventing SC apoptosis induced by high glucose levels. RSC96 cells pretreated with oltipraz were cultured in high-glucose medium (50 mM glucose) for 24 h, and cells cultured in medium containing 5 mM glucose were used as the control. Flow cytometry was used to evaluate the degree of apoptosis. A Cell Counting Kit-8 assay was used to assess cell viability. The mitochondrial membrane potential was assessed using JC-1 staining, and reactive oxygen species (ROS) generation was measured using 20,70-dichlorodihydrofluorescein diacetate staining. In addition, the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) levels were also evaluated using the corresponding kits. Flow cytometry was subsequently used to detect apoptosis, and western blotting was used to measure the expression levels of nuclear factor erythroid derived-2-related factor 2 and NADPH quinone oxidoreductase 1. The results showed that high glucose concentration increased oxidative stress and apoptosis in RSC96 cells. Oltipraz improved cell viability and reduced apoptosis of RSC96 cells in the high glucose environment. Additionally, oltipraz exhibited a significant antioxidative effect, as shown by the decrease in MDA levels, increased SOD levels, and reduced ROS generation in RSC96 cells. The results of the present study suggest that oltipraz exhibits potential as an effective drug for treatment with DPN.

The deleterious role of the prostaglandin E2 EP3 receptor in angiotensin II hypertension

Angiotensin II (ANG II) plays a key role in regulating blood pressure and inflammation. Prostaglandin E₂ (PGE₂) signals through four different G protein-coupled receptors, eliciting a variety of effects. We reported that activation of the EP₃ receptor reduces cardiac contractility. More recently, we have shown that overexpression of the EP₄ receptor is protective in a mouse myocardial infarction model. We hypothesize in this study that the relative abundance of EP₃ and EP₄ receptors is a major determinant of end-organ damage in the diseased heart. Thus EP₃ is detrimental to cardiac function and promotes inflammation, whereas antagonism of the EP₃ receptor is protective in an ANG II hypertension (HTN) model. To test our hypothesis, male 10- to 12-wk-old C57BL/6 mice were anesthetized with isoflurane and osmotic minipumps containing ANG II were implanted subcutaneously for 2 wk. We found that antagonism of the EP₃ receptor using L798,106 significantly attenuated the increase in blood pressure with ANG II infusion. Moreover, antagonism of the EP₃ receptor prevented a decline in cardiac function after ANG II treatment. We also found that 10- to 12-wk-old EP₃-transgenic mice, which overexpress EP₃ in the cardiomyocytes, have worsened cardiac function. In conclusion, activation or overexpression of EP₃ exacerbates end-organ damage in ANG II HTN. In contrast, antagonism of the EP₃ receptor is beneficial and reduces cardiac dysfunction, inflammation, and HTN.NEW & NOTEWORTHY This study is the first to show that systemic treatment with an EP₃ receptor antagonist (L798,106) attenuates the angiotensin II-induced increase in blood pressure in mice. The results from this project could complement existing hypertension therapies by combining blockade of the EP₃ receptor with antihypertensive drugs.

Analgesic and Antidepressant Effects of Oltipraz on Neuropathic Pain in Mice by Modulating Microglial Activation

Nerve injury provokes microglial activation, contributing to the sensory and emotional disorders associated with neuropathic pain that do not completely resolve with treatment. In C57BL/6J mice with neuropathic pain induced by chronic constriction of the sciatic nerve (CCI), we evaluated the effects of oltipraz, an antioxidant and anticancer compound, on (1) allodynia and hyperalgesia, (2) microglial activation and pain signaling pathways, (3) oxidative stress, and (4) depressive-like behaviors. Twenty-eight days after surgery, we assessed the effects of oltipraz on the expression of CD11b/c (a microglial marker), phosphoinositide 3-kinase (PI3K)/ phosphorylated protein kinase B (p-Akt), nuclear factor-κB (NF-κB) transcription factor, and mitogen activated protein kinases (MAPK) in the spinal cord, hippocampus, and prefrontal cortex. Our results show that oltipraz alleviates neuropathic pain by inhibiting microglial activation and PI3K/p-Akt, phosphorylated inhibitor of κBα (p-IκBα), and MAPK overexpression, and by normalizing and/or enhancing the expression of antioxidant proteins, nuclear factor erythroid derived-2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), and NAD(P)H:quinone oxidoreductase-1 (NQO1) in the spinal cord. The inhibition of microglial activation and induction of the Nrf2/HO-1/NQO1 signaling pathway in the hippocampus and/or prefrontal cortex may explain the antidepressant effects of oltipraz during neuropathic pain. These data demonstrate the analgesic and antidepressant effects of oltipraz and reveal its protective and antioxidant properties during chronic pain.