Intermedin protects thapsigargin‑induced endoplasmic reticulum stress in cardiomyocytes by modulating protein kinase A and sarco/endoplasmic reticulum Ca2+‑ATPase

Pharmacokinetics and antioxidant activity of dihydrocaffeic acid grafted chitosan nanomicelles loaded with chicoric acid in broilers

Chicoric acid (CA) is a natural nutrient found in plants, showcasing diverse biological activities, including anti-inflammatory and antioxidant properties. Despite its valuable properties, CA faces limitations in bioavailability and susceptibility to oxidative breakdown during utilization. Previous research introduced synthesized dihydrocaffeic acid grafted chitosan self-assembled nanomicelles (DA-g-CS), demonstrating its potential to enhance CA absorption. This study aims to investigate the pharmacokinetics, tissue distribution, and antioxidant activity of both CA and DA-g-CS loaded CA (DA-g-CS/CA) in broilers. An IPEC-J2 cell model was established and evaluated to delve deeper into the transport mechanism and antioxidant potential. The in vivo pharmacokinetic analysis in broilers highlighted a substantial difference: the maximum plasma concentration (Cmax) of DA-g-CS/CA exceeded CA by 2.6-fold, yielding a notable increased relative bioavailability to 214%. This evidence underscores the significant enhancement in CA's oral absorption, facilitated by DA-g-CS. The collective evaluation outcomes affirm the successful development of the cell model, indicating its suitability for drug transporter experiments. The findings from the intestinal transit analysis revealed that both CA and DA-g-CS/CA underwent passive entry into IPEC-J2 cells. Notably, the cellular uptake rate of DA-g-CS loaded with CA was significantly amplified, reaching 2.1 times higher than that of CA alone. Intracellular transport mechanisms involved microtubules, lysosomes, and the endoplasmic reticulum, with an additional pathway involving the endoplasmic reticulum observed specifically for DA-g-CS/CA, distinguishing it from CA. Moreover, the results from both in vivo and in vitro antioxidant assessments highlight the potent antioxidant activity of DA-g-CS/CA, showcasing its efficacy in preventing and treating cellular damage induced by oxidative stress. In summary, these findings underscore the significant enhancement of CA's efficacy facilitated by DA-g-CS, establishing a robust theoretical foundation for the prospective application of CA within livestock and poultry farming.

Sensitivity and activation of endoplasmic reticulum stress response and apoptosis in the perinatal sheep heart

Although the unfolded protein response (UPR) contributes to survival by removing misfolded proteins, endoplasmic reticulum (ER) stress also activates proapoptotic pathways. Changed sensitivity to normal developmental stimuli may underlie observed cardiomyocyte apoptosis in the healthy perinatal heart. We determined in vitro sensitivity to thapsigargin in sheep cardiomyocytes from four perinatal ages. In utero cardiac activation of ER stress and apoptotic pathways was determined at these same ages. Thapsigargin-induced phosphorylation of eukaryotic initiation factor 2 (EIF2A) was decreased by 72% between 135 and 143 dGA (P = 0.0096) and remained low at 1 dPN (P = 0.0080). Conversely, thapsigargin-induced caspase cleavage was highest around the time of birth: cleaved caspase 3 was highest at 1 dPN (3.8-fold vs. 135 dGA, P = 0.0380; 7.8-fold vs. 5 dPN, P = 0.0118), cleaved caspase 7 and cleaved caspase 12 both increased between 135 and 143 dGA (25-fold and 6.9-fold respectively, both P < 0.0001) and remained elevated at 1 dPN. Induced apoptosis, measured by TdT-mediated dUTP nick-end labeling (TUNEL) assay, was highest around the time of birth (P < 0.0001). There were changes in myocardial ER stress pathway components in utero. Glucose (78 kDa)-regulated protein (GRP78) protein levels were high in the fetus and declined after birth (P < 0.0001). EIF2A phosphorylation was profoundly depressed at 1 dPN (vs. 143 dGA, P = 0.0113). In conclusion, there is dynamic regulation of ER proteostasis, ER stress, and apoptosis cascade in the perinatal heart. Apoptotic signaling is more readily activated in fetal cardiomyocytes near birth, leading to widespread caspase cleavage in the newborn heart. These pathways are important for the regulation of normal maturation in the healthy perinatal heart.NEW & NOTEWORTHY Cardiomyocyte apoptosis occurs even in the healthy, normally developing perinatal myocardium. As cardiomyocyte number is a critical contributor to heart health, the sensitivity of cardiomyocytes to endoplasmic reticulum stress leading to apoptosis is an important consideration. This study suggests that the heart has less robust protective mechanisms in response to endoplasmic reticulum stress immediately before and after birth, and that more cardiomyocyte death can be induced by stress in this period.

Mitochondrial Melatonin: Beneficial Effects in Protecting against Heart Failure

Cardiovascular disease is the cause of physical infirmity and thousands of deaths annually. Typically, during heart failure, cardiomyocyte mitochondria falter in terms of energy production and metabolic processing. Additionally, inflammation and the accumulation of non-contractile fibrous tissue contribute to cardiac malfunction. Melatonin, an endogenously produced molecule, experimentally reduces the initiation and progression of atherosclerotic lesions, which are often the basis of coronary artery disease. The current review critically analyzes published data related to the experimental use of melatonin to forestall coronary artery pathologies. Collectively, these studies document melatonin's anti-atherosclerotic actions in reducing LDL oxidation and triglyceride levels, lowering endothelial malfunction, limiting adhesion molecule formation, preventing macrophage polarization to the M1 pro-inflammatory phenotype, changing cellular metabolism, scavenging destructive reactive oxygen species, preventing the proliferation and invasion of arterial smooth muscle cells into the lesioned area, restricting the ingrowth of blood vessels from the vasa vasorum, and solidifying the plaque cap to reduce the chance of its rupture. Diabetic hyperglycemia, which aggravates atherosclerotic plaque formation, is also inhibited by melatonin supplementation in experimental animals. The potential value of non-toxic melatonin as a possible inhibitor of cardiac pathology in humans should be seriously considered by performing clinical trials using this multifunctional molecule.

Protective effect of naringin against radiation-induced heart disease in rats via Sirt1/NF-κB signaling pathway and endoplasmic reticulum stress

This study was designed to explore the protective effect and mechanism of naringin (NG) on radiation-induced heart disease (RIHD) in rats. Rats were divided into four x-ray (XR) irradiation groups with different absorbed doses (0/10/15/20 Gy), or into three groups (control, XR, and XR + NG groups). Subsequently, the ultrasonic diagnostic apparatus was adopted to assess and compare the left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), left ventricular internal diameter at end diastole (LVIDd), and left ventricular internal diameter at end systole (LVIDs) in rats. Hematoxylin-eosin (H&E) staining and Masson staining were applied to detect the pathological damage and fibrosis of heart tissue. Western blot was used to measure the expression levels of myocardial fibrosis-related proteins, endoplasmic reticulum stress-related proteins, and Sirt1 (silent information regulator 1)/NF-κB (nuclear factor kappa-B) signaling pathway-related proteins in cardiac tissues. Additionally, enzyme-linked immunosorbent assay was utilized to detect the activities of pro-inflammatory cytokines, malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) in cardiac tissue. The results showed that NG treatment significantly attenuated the 20 Gy XR-induced decline of LVEF and LVFS and the elevation of LVIDs. Cardiac tissue damage and fibrosis caused by 20 Gy XR were significant improved after NG treatment. Meanwhile, in rats irradiated by XR, marked downregulation was identified in the expressions of fibrosis-related proteins (Col I, collagen type I; α-SMA, α-smooth muscle actin; and TGF-β1, transforming growth factor-beta 1) and endoplasmic reticulum stress-related proteins (GRP78, glucose regulatory protein 78; CHOP, C/EBP homologous protein; ATF6, activating transcription factor 6; and caspase 12) after NG treatment. Moreover, NG treatment also inhibited the production of pro-inflammatory cytokines [interleukin-6, interleukin-1β, and monocyte chemoattractant protein-1 (MCP-1)], reduced the expression of MDA, and promoted the activities of SOD and CAT. Also, NG treatment promoted Sirt1 expression and inhibited p65 phosphorylation. Collectively, XR irradiation induced cardiac injury in rats in a dose-dependent manner. NG could improve the cardiac injury induced by XR irradiation by inhibiting endoplasmic reticulum stress and activating Sirt1/NF-κB signaling pathway.

Pharmacokinetics, absorption and transport mechanism for ginseng polysaccharides

BACKGROUND

Ginseng polysaccharide (GP) is one of the most abundant components in Panax ginseng. However, the absorption pathways and mechanisms of GPs have not been investigated systematically due to the challenges of their detection.

METHODS

The fluorescein isothiocyanate derivative (FITC) was employed to label GP and ginseng acidic polysaccharide (GAP) to obtain target samples. HPLC-MS/MS assay was used to determine the pharmacokinetics of GP and GAP in rats. The Caco-2 cell model was used to investigate the uptake and transport mechanisms of GP and GAP in rats.

RESULTS

Our results demonstrated that the absorption of GAP was more than that of GP in rats after gavage administration, while there was no significant difference between both after intravenous administration. In addition, we found that GAP and GP were more distributed in the kidney, liver and genitalia, suggesting that GAP and GP are highly targeted to the liver, kidney and genitalia. Importantly, we explored the uptake mechanism of GAP and GP. GAP and GP are endocytosed into the cell via lattice proteins or niche proteins. Both are transported lysosomally mediated to the endoplasmic reticulum (ER) and then enter the nucleus through the ER, thus completing the process of intracellular uptake and transportation.

CONCLUSION

Our results confirm that the uptake of GPs by small intestinal epithelial cells is primarily mediated via lattice proteins and the cytosolic cellar. The discovery of important pharmacokinetic properties and the uncovering of the absorption mechanism provide a research rationale for the research of GP formulation and clinical promotion.

ER stress induces upregulation of transcription factor Tbx20 and downstream Bmp2 signaling to promote cardiomyocyte survival

In the mammalian heart, fetal cardiomyocytes proliferate prior to birth; however, they exit the cell cycle shortly after birth. Recent studies show that adult cardiomyocytes re-enters the cell cycle postinjury to promote cardiac regeneration. The endoplasmic reticulum (ER) orchestrates the production and assembly of different types of proteins, and a disruption in this machinery leads to the generation of ER stress, which activates the unfolded protein response. There is a very fine balance between ER stress-mediated protective and proapoptotic responses. T-box transcription factor 20 (Tbx20) promotes embryonic and adult cardiomyocyte proliferation postinjury to restore cardiac homeostasis. However, the function and regulatory interactions of Tbx20 in ER stress-induced cardiomyopathy have not yet been reported. We show here that ER stress upregulates Tbx20, which activates downstream bone morphogenetic protein 2 (Bmp2)-pSmad1/5/8 signaling to induce cardiomyocyte proliferation and limit apoptosis. However, augmenting ER stress reverses this protective response. We also show that increased expression of tbx20 during ER stress is mediated by the activating transcription factor 6 arm of the unfolded protein response. Cardiomyocyte-specific loss of Tbx20 results in decreased cardiomyocyte proliferation and increased apoptosis. Administration of recombinant Bmp2 protein during ER stress upregulates Tbx20 leading to augmented proliferation, indicating a feed-forward loop mechanism. In in vivo ER stress, as well as in diabetic cardiomyopathy, the activity of Tbx20 is increased with concomitant increased cardiomyocyte proliferation and decreased apoptosis. These data support a critical role of Tbx20-Bmp2 signaling in promoting cardiomyocyte survival during ER stress-induced cardiomyopathies.

Lycium barbarum L. and Salvia miltiorrhiza Bunge protect retinal pigment epithelial cells through endoplasmic reticulum stress

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum L. and Salvia miltiorrhiza Bunge (Gouqi and Danshen, LS) are traditional herbs for the treatment of retinal degeneration in China. LS have been integrated into pharmacopoeia and health care system of many countries around the world. However, the mechanisms by which LS protect retina are not fully clarified.

AIM OF THE STUDY

We aimed at exploration of the effect of LS on retinal pigment epithelium (RPE) cells apoptosis as well as the endoplasmic reticulum (ER) stress mechanisms.

MATERIAL AND METHODS

ARPE-19 cells were exposed to tunicamycin to induce ER stress, followed by LS treatment for 24 h. The cell morphology was photographed using the Incucyte S3 instrument, and the potential cytotoxic effect and viability were evaluated by CCK-8 assays. The Annexin V-FITC/PI staining and TUNEL assay were conducted to detect cells apoptotic. Western blot and digital PCR were used to detected related protein and gene expression.

RESULTS

The ARPE-19 cells are increased in number and aligned after treating with LS. 1 mg/ml is the LS high dose group dose and treatment with LS increased cell vitality. LS significantly inhibit ARPE-19 cells apoptosis. Moreover, LS were markedly decreased the expression levels of ER stress-related factors in the ARPE-19 cells.

CONCLUSIONS

This study reveals that LS relieve ARPE-19 cells apoptosis by inhibiting ER stress, and here we can speculate that LS have a certain protective effect on retina.

Dapagliflozin attenuates pressure overload-induced myocardial remodeling in mice via activating SIRT1 and inhibiting endoplasmic reticulum stress

Endoplasmic reticulum stress-mediated apoptosis plays a vital role in the occurrence and development of heart failure. Dapagliflozin (DAPA), a new type of sodium-glucose cotransporter 2 (SGLT2) inhibitor, is an oral hypoglycemic drug that reduces glucose reabsorption by the kidneys and increases glucose excretion in the urine. Studies have shown that DAPA may have the potential to treat heart failure in addition to controlling blood sugar. This study explored the effect of DAPA on endoplasmic reticulum stress-related apoptosis caused by heart failure. In vitro, we found that DAPA inhibited the expression of cleaved caspase 3, Bax, C/EBP homologous protein (CHOP), and glucose-regulated protein78 (GRP78) and upregulated the cardiomyoprotective protein Bcl-2 in angiotensin II (Ang II)-treated cardiomyocytes. In addition, DAPA promoted the expression of silent information regulator factor 2-related enzyme 1 (SIRT1) and suppressed the expression of activating transcription factor 4 (ATF4) and the ratios p-PERK/PERK and p-eIF2α/eIF2α. Notably, the therapeutic effect of DAPA was weakened by pretreatment with the SIRT1 inhibitor EX527 (10 μM). Simultaneous administration of DAPA inhibited the Ang II-induced transformation of fibroblasts into myofibroblasts and inhibited fibroblast migration. In summary, our present findings first indicate that DAPA could inhibit the PERK-eIF2α-CHOP axis of the ER stress response through the activation of SIRT1 in Ang II-treated cardiomyocytes and ameliorate heart failure development in vivo.

Investigation of the internalization and transport mechanism of Codonopsis Radix polysaccharide both in mice and Caco-2 cells

For Codonopsis Radix polysaccharides (CRPs), oral administration is generally considered the most convenient route for patients. However, the details of its absorption and transport mechanisms remain unclear. In this study, we aimed to evaluate the oral absorption of CPA (an inulin-type fructan extracted from CRPs) in mice and Caco-2 cells. It was labeled with fluorescein isothiocyanate, and the fluorescence derivative (FCPA) was used to trace the behavior of CPA. The results showed that FCPA could be absorbed after oral administration and has a wide tissue distribution, including in the stomach, intestine, kidneys, and liver. FCPA was poorly absorbed, and its internalization was time- and energy-dependent, as well as dependent on cholesterol- and dynamin-mediated endocytosis. Confocal laser scanning microscopy showed successful cellular internalization of FCPA from the cytoplasm to the nucleus. In addition, we found that FCPA was trafficked to endosomes and lysosomes, and that tubulin was required for its intracellular transport. These findings add new details to our knowledge of the internalization and transport mechanisms of CPA, which may prove useful to the development and application of oral formulations of CRPs.

Taurine attenuates ER stress‑associated apoptosis and catabolism in nucleus pulposus cells

Nucleus pulposus (NP) apoptosis and subsequent excessive degradation of the extracellular matrix (ECM) are key pathological characteristics of intervertebral disc degeneration (IDD). The present study aims to examine the signaling processes underlying the effects of taurine on IDD, with specific focus on endoplasmic reticulum (ER) stress-mediated apoptosis and ECM degradation, in NP cells. To clarify the role of taurine in IDD, NP cells were treated with various concentrations of taurine and IL-1β or thapsigargin (TG). Cell Counting Kit-8, western blotting, TUNEL, immunofluorescence assays and reverse transcription-quantitative PCR were applied to measure cell viability, the expression of ER stress-associated proteins (GRP78, CHOP and caspase-12), apoptosis and the levels of metabolic factors associated with ECM (MMP-1, 3, 9, ADAMTS-4, 5 and collagen II), respectively. Taurine was found to attenuate ER stress and prevent apoptosis in NP cells induced by IL-1β treatment. Additionally, taurine significantly decreased the expression of ER stress-activated glucose regulatory protein 78, C/EBP homologous protein and caspase-12. TUNEL results revealed that taurine decreased the number of apoptotic TG-treated NP cells. TG-treated NP cells also exhibited characteristics of increased ECM degradation, supported by observations of increased MMP-1, MMP-3, MMP-9 and A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4 and ADAMTS-5 expression in addition to decreased collagen-II expression. However, taurine treatment significantly reversed all indicators of excessive ECM catabolism aforementioned. These data suggest that taurine can mediate protection against apoptosis and ECM degradation in NP cells by inhibiting ER stress, implicating therapeutic potential for the treatment of IDD.

Study on Protection of Human Umbilical Vein Endothelial Cells from Amiodarone-Induced Damage by Intermedin through Activation of Wnt/β-Catenin Signaling Pathway

Amiodarone (AM) is one of the most effective antiarrhythmic drugs and normally administrated by intravenous infusion which is liable to cause serious phlebitis. The therapeutic drugs for preventing this complication are limited. Intermedin (IMD), a member of calcitonin family, has a broad spectrum of biological effects including anti-inflammatory effects, antioxidant activities, and antiapoptosis. But now, the protective effects of IMD against amiodarone-induced phlebitis and the underlying molecular mechanism are not well understood. In this study, the aim was to investigate the protective efficiency and potential mechanisms of IMD in amiodarone-induced phlebitis. The results of this study revealed that treatment with IMD obviously attenuated apoptosis and exfoliation of vascular endothelial cells and infiltration of inflammatory cells in the rabbit model of phlebitis induced by intravenous infusion of amiodarone compared with control. Further tests in vitro demonstrated that IMD lessened amiodarone-induced endothelial cell apoptosis, improved amiodarone-induced oxidative stress injury, reduced inflammatory reaction, and activated the Wnt/β-catenin signal pathway which was inhibited by amiodarone. And these effects could be reversed by Wnt/β-catenin inhibitor IWR-1-endo, and si-RNA knocked down the gene of Wnt pathway. These results suggested that IMD exerted the protective effects against amiodarone-induced endothelial injury via activating the Wnt/β-catenin pathway. Thus, IMD could be used as a potential agent for the treatment of phlebitis.