Cateslytin abrogates lipopolysaccharide-induced cardiomyocyte injury by reducing inflammation and oxidative stress through toll like receptor 4 interaction

Tomentosin mitigates the LPS induced cardiac injury by regulating Nrf-2/Nf-κβ pathway in mice

Endotoxemic shock is a severe complication characterized by multiple organ failure, hypotension, and impaired tissue perfusion, all contributing to high morbidity and mortality. Recent studies have highlighted the anti-inflammatory and antioxidant properties of tomentosin. This study investigates the protective effects of tomentosin against lipopolysaccharide (LPS)-induced cardiac injury and elucidates its underlying mechanisms. Mice were pre-treated with tomentosin before the LPS administration. Subsequently, cardiac injury markers, oxidative stress parameters, inflammatory mediators, and Nrf-2/NF-κB protein expression levels were analysed. The results demonstrated that tomentosin significantly reduced Troponin and CK-MB levels, alleviated oxidative stress, and suppressed inflammatory responses. Furthermore, tomentosin inhibited NF-κB activation while enhancing Nrf-2 expression. In conclusion, our findings suggest that tomentosin exerts cardioprotective effects by modulating the Nrf-2/NF-κB pathway, positioning it as a potential therapeutic candidate for preventing LPS-induced cardiac dysfunction.

A complex role of chromogranin A and its peptides in inflammation, autoimmunity, and infections

Chromogranin A (CgA), mostly known as a nonspecific neuroendocrine tumor marker, was the first glycoprotein from the granin family characterized as a prohormone for various bioactive peptides including vasostatin I/II (VS-I, VS-II), catestatin (CST), chromofungin (CHR), pancreastatin (PST), WE-14, and others. CgA and its derivatives present various functions, often antagonistic, in maintaining body homeostasis and influencing the immune system. This review aims to summarize the not fully understood role of CgA and its derivatives in inflammation, autoimmunity, and infections. CgA seems to be involved in the complex pathophysiology of cardiovascular disorders, neurodegenerative diseases, and other conditions where immune system dysfunction plays a role in the onset and development of the disease (e.g. systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), or rheumatoid arthritis (RA)). However, the direct immunomodulatory role of CgA is difficult to assess since many of its activities may be linked with its peptides. CST and VS-I are considered anti-inflammatory molecules, due to M2 macrophage polarization stimulation and downregulation of certain proinflammatory cytokines. Conversely, PST is reported to stimulate proinflammatory M1 macrophage polarization and Th1 lymphocyte response. Thus, the final effects of CgA in inflammation may depend on its cleavage pattern. Additionally, peptides like CST, VS-I, or CHR exert direct antimicrobial/antifungal activities. CgA, WE-14, and other less-known CgA-derived peptides have also been reported to trigger autoimmune responses, highly studied in type 1 diabetes mellitus. Overall, CgA and its derivatives have an interesting but complex role in immunity, however, their specific roles require further research.

A recombinant fragment antigen-binding (Fab) of trastuzumab displays low cytotoxic profile in adult human cardiomyocytes: first evidence and the key implication of FcγRIIA receptor

Fragment crystallizable gamma receptors (FcγRs) mediate various cellular responses with significant cardiovascular implications. They contribute to the anticancer activity of trastuzumab (TRZ), a recombinant humanized monoclonal antibody that interferes with human epidermal growth factor receptor 2 (HER2), thereby blocking its physiological function in cardiac cells. This is responsible for cardiac complications that hamper TRZ clinical application. In this study we investigated the involvement of FcγRs in the TRZ cardiotoxicity. We used a recombinant antigen-binding fragment (Fab) of TRZ (rFab-HER2) to examine whether the absence of the Fc region resulted in fewer cardiomyocyte toxicity while preserving TRZ's ability to inhibit HER2. When exposed to rFab-HER2, AC16 human adult ventricular cardiomyocytes were less vulnerable to damage and death, than to TRZ. Specifically, TRZ exhibited cytotoxicity at a lower concentration (150 µg/mL, corresponding to ~1 µM) compared to rFab-HER2 (250 µg/mL, corresponding to ~5 µM). Like TRZ, rFab-HER2 negatively modulated HER2 levels in cardiomyocyte (without inducing cytotoxic activity in BJ human fibroblast cells that either did not express or express very low levels of HER2) and inhibited the downstream ERK/AKT cascades. But rFab-HER2 did not alter cardiomyocyte mitochondrial dynamic balance, and affect apoptosis and inflammation, while it limited cytosolic and mitochondrial ROS indicators. On contrary, the Fc region (50-250 μg/mL) exerted direct cytotoxic action on cardiomyocytes (but not on human fibroblasts that lacked Fc receptors). TRZ (150 μg/mL) markedly upregulated the expression level of FcγRIIA (a FcγRs strongly involved in TRZ-induced antibody-dependent cellular toxicity) in cardiomyocytes, whereas the Fab fragment (150 μg/mL) had no effect. Our results demonstrate that Fc region plays an important pathogenic role in TRZ-induced cardiomyocyte toxicity. In addition, targeting FcγRIIA might contribute to the off-target effects of TRZ therapy.

Radix Sophorae Flavescentis of Sophora flavescens Aiton inhibits LPS-induced macrophage pro-inflammatory response via regulating CFHR2 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Long-term chronic inflammation often leads to chronic diseases. Although Sophora flavescens has been shown to have anti-inflammatory properties, its detailed molecular mechanism is still unknown.

AIM OF STUDY

This study investigated the effect of Radix Sophorae Flavescentis on the LPS-induced inflammatory response in macrophages.

MATERIALS AND METHODS

LPS was used to induce the peritoneal macrophages to simulate the inflammatory environment in vitro. Different concentrations of Radix Sophorae Flavescentis-containing (medicated) serum were used for intervention. The peritoneal macrophages were identified by using hematoxylin-eosin and immunofluorescence staining. ELISA was used to measure the TNF-α and IL-6 expression to determine the concentration of LPS. ELISA and Western blot (WB) were used to detect the PGE2 and CFHR2 expression in each group, respectively. The lentiviral vector for interference and overexpression of the CFHR2 gene was constructed, packaged, and transfected into LPS-induced macrophages. The transfection efficiency was verified by WB. Then, ELISA was used to detect the TNF-α, PGE2, and IL-6 expression. WB was used to detect the CFHR2, iNOS, COX-2, TLR2, TLR4, IFN-γ, STAT1, and p-STAT1 expression.

RESULTS

The primary isolated cells were identified as macrophages. The LPS-treated macrophages exhibited significantly higher expression of PGE2 and CFHR2, and the inflammatory factors TNF-α and IL-6, as well as iNOS, COX-2, TLR2, TLR4, IFN-γ, STAT1, and p-STAT1 expression compared with the control group (P < 0.05). The TNF-α, PGE2, and IL-6 levels, as well as CFHR2, iNOS, COX-2, TLR2, TLR4, IFN-γ, STAT1, and p-STAT1 expression were considerably lower in the LPS-induced+10% medicated-serum group, LPS-induced+20% medicated-serum group, and shCFHR interference group compared with the LPS group (P < 0.05).

CONCLUSION

Radix Sophorae Flavescentis might mediate CFHR2 expression and play an important role in inhibiting the LPS-induced pro-inflammatory response of macrophages. Radix Sophorae Flavescentis could be a potential treatment for LPS-induced related inflammatory diseases.

The redox-active defensive Selenoprotein T as a novel stress sensor protein playing a key role in the pathophysiology of heart failure

Maladaptive cardiac hypertrophy contributes to the development of heart failure (HF). The oxidoreductase Selenoprotein T (SELENOT) emerged as a key regulator during rat cardiogenesis and acute cardiac protection. However, its action in chronic settings of cardiac dysfunction is not understood. Here, we investigated the role of SELENOT in the pathophysiology of HF: (i) by designing a small peptide (PSELT), recapitulating SELENOT activity via the redox site, and assessed its beneficial action in a preclinical model of HF [aged spontaneously hypertensive heart failure (SHHF) rats] and against isoproterenol (ISO)-induced hypertrophy in rat ventricular H9c2 and adult human AC16 cardiomyocytes; (ii) by evaluating the SELENOT intra-cardiomyocyte production and secretion under hypertrophied stimulation. Results showed that PSELT attenuated systemic inflammation, lipopolysaccharide (LPS)-induced macrophage M1 polarization, myocardial injury, and the severe ultrastructural alterations, while counteracting key mediators of cardiac fibrosis, aging, and DNA damage and restoring desmin downregulation and SELENOT upregulation in the failing hearts. In the hemodynamic assessment, PSELT improved the contractile impairment at baseline and following ischemia/reperfusion injury, and reduced infarct size in normal and failing hearts. At cellular level, PSELT counteracted ISO-mediated hypertrophy and ultrastructural alterations through its redox motif, while mitigating ISO-triggered SELENOT intracellular production and secretion, a phenomenon that presumably reflects the extent of cell damage. Altogether, these results indicate that SELENOT could represent a novel sensor of hypertrophied cardiomyocytes and a potential PSELT-based new therapeutic approach in myocardial hypertrophy and HF.

Effect of L-carnitine in Ameliorating Lipopolysaccharide-Induced Cardiomyocyte Injury via MAPK Signaling

The present study aimed to elucidate whether L-carnitine (LC) protected H9c2 cells and its underlying mechanisms. Cell counting kit-8 (CCK-8) assay was used to evaluate cell viability. Apoptosis, cell morphology, and lactate dehydrogenase (LDH) assessment were used to prove effects of lipopolysaccharide (LPS) and LC on H9c2 cells. RT-qPCR and western blot assays were hired to evaluate the mRNA and protein expression levels, respectively. ELISA assay was performed to determine the released protein levels. Reactive oxygen species (ROS) level was evaluated by immunofluorescence and flow cytometry. LC was revealed to protect H9c2 cells against LPS-induced injury as indicated by increased cell viability, reduced apoptosis ratio and LDH level. LC treatment also reduced BAX expression as well as up-regulated Bcl-2 expression under LPS treatment. Mechanically, LC reduced oxidative stress and ameliorated the mitochondrial injury through modulating extracellular signal-regulated kinase 1/2 and c-Jun N-terminal protein kinase c-Jun N-terminal protein kinase phosphorylation levels as indicated by decreased membrane potential, increased ATP production and mtDNA expression. We found that LC ameliorates LPS-induced cardiomyocyte injury by abrogating cell apoptosis ratio, ROS levels, as well as mitochondrial dysfunction via mitogen-activated protein kinase signaling. Our findings revealed a potential drug for sepsis or LPS-induced cardiomyocyte injury.

Astragalus Complanatus Ethanol Attenuates Septic Shock by Exerting Anti-Inflammatory Effects on Macrophages

Sepsis is a systemic inflammatory syndrome that results in multiple-organ failure caused by a dysregulated host immune response to microbial infection. Astragali complanati semen extract (ACSE) exhibits pharmacological activities, including antioxidant, anticancer, antiaging, and anti-diabetes effects. It is widely used in traditional medicine to treat liver and kidney diseases; however, the protective effect of ACSE on sepsis and its mechanisms are unknown. In the present study, we investigated the anti-inflammatory effects and potential mechanisms of the action of ACSE on sepsis. We show that ACSE improved survival rates in mouse models of acute sepsis induced by CLP (cecal ligation and puncture) and LPS stimulation. ACSE administration decreased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in sepsis-induced mice. Furthermore, ACSE reduced the levels of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in the serum of septic mice. ACSE treatment inhibited the expression of these proinflammatory genes in LPS-stimulated J774 macrophages. Moreover, ACSE inhibited the phosphorylation of the IκB kinase (IKK) and the nuclear translocation of p65 NF-κB by LPS stimulation in macrophages. These results reveal the mechanism underlying the protective effect of ACSE against sepsis by inhibiting NF-κB activation and suggest that ACSE could be a potential therapeutic candidate to treat acute inflammatory diseases.

Network pharmacology-based approach to explore the underlying mechanism of sinomenine on sepsis-induced myocardial injury in rats

Background: Sepsis, a systemic disease, usually induces myocardial injury (MI), and sepsis-induced MI has become a significant contributor to sepsis-related deaths in the intensive care unit. The objective of this study is to investigate the role of sinomenine (SIN) on sepsis-induced MI and clarify the underlying mechanism based on the techniques of network pharmacology. Methods: Cecum ligation and puncture (CLP) was adopted to induce sepsis in male Sprague-Dawley (SD) rats. Serum indicators, echocardiographic cardiac parameters, and hematoxylin and eosin (H&E) staining were conducted to gauge the severity of cardiac damage. The candidate targets and potential mechanism of SIN against sepsis-induced MI were analyzed via network pharmacology. Enzyme-linked immunosorbent assay was performed for detecting the serum concentration of inflammatory cytokines. Western blot was applied for evaluating the levels of protein expression. Terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labeling assay was applied to assess cardiomyocyte apoptosis. Results: SIN significantly improved the cardiac functions, and attenuated myocardial structural damage of rats as compared with the CLP group. In total, 178 targets of SIN and 945 sepsis-related genes were identified, and 33 overlapped targets were considered as candidate targets of SIN against sepsis. Enrichment analysis results demonstrated that these putative targets were significantly associated with the Interleukin 17 (IL-17) signal pathway, inflammatory response, cytokines-mediated signal pathway, and Janus Kinase-Signal Transducers and Activators of Transcription (JAK-STAT) pathway. Molecular docking suggested that SIN had favorable binding affinities with Mitogen-Activated Protein Kinase 8 (MAPK8), Janus Kinase 1 (JAK1), Janus Kinase 2 (JAK2), Signal Transducer and Activator of Transcription 3 (STAT3), and nuclear factor kappa-B (NF-κB). SIN significantly reduced the serum concentration of Tumor Necrosis Factor-α (TNF-α), Interleukin 1 Beta (IL-1β), Interleukin 6 (IL-6), Interferon gamma (IFN-γ), and C-X-C Motif Chemokine Ligand 8 (CXCL8), lowered the protein expression of phosphorylated c-Jun N-terminal kinase 1 (JNK1), JAK1, JAK2, STAT3, NF-κB, and decreased the proportion of cleaved-caspase3/caspase3. In addition, SIN also significantly inhibited the apoptosis of cardiomyocytes as compared with the CLP group. Conclusion: Based on network pharmacology analysis and corresponding experiments, it was concluded that SIN could mediate related targets and pathways to protect against sepsis-induced MI.

Cardiac-specific overexpression of catalase attenuates lipopolysaccharide-induced cardiac anomalies through reconciliation of autophagy and ferroptosis

Lipopolysaccharide (LPS) from Gram-negative bacteria is a major contributor to cardiovascular failure, but the signaling mechanisms underlying its stress response are not fully understood. This study aimed to investigate the effect of the antioxidant enzyme catalase on LPS-induced cardiac abnormalities and the mechanisms involved, with particular focus on the interplay between autophagy, ferroptosis, and apoptosis. Cardiac-specific catalase (CAT) overexpression and wild-type (WT) mice were stimulated with LPS (6 mg/kg, intravenous injection), and cardiac morphology and function were evaluated. Oxidative stress, ferroptosis, apoptosis, and mitochondrial status were monitored, and survival curves were plotted based on the results of LPS stimulation. The results showed that, compared with WT mice, mice overexpressing catalase had a higher survival rate under LPS stimulation. Ultrasound echocardiography, cardiomyocyte characteristics, and Masson's trichrome staining showed that LPS inhibited cardiac function and caused cardiac fibrosis, while catalase alleviated these adverse effects. LPS increased apoptosis (TUNEL, caspase-3 activation, cleaved caspase-3), increased O₂^·- production, induced inflammation (TNF-α), autophagy, iron toxicity, and carbonyl damage, and significantly damaged mitochondria (mitochondrial membrane potential, mitochondrial proteins, and ultrastructure). These effects were significantly alleviated by catalase. Interestingly, the antioxidant N-acetylcysteine, autophagy inhibitor 3-methyladenine, and ferroptosis inhibitor lipostatin-1 all eliminated the LPS-induced contraction dysfunction and ferroptosis (using lipid peroxidation). Induction of ferroptosis could eliminate the cardioprotective effect of NAC. In conclusion, catalase rescues LPS-induced cardiac dysfunction by regulating oxidative stress, autophagy, ferroptosis, apoptosis, and mitochondrial damage in cardiomyocytes.

Inflammatory mechanisms and intervention strategies for sepsis-induced myocardial dysfunction

Sepsis-induced myocardial dysfunction (SIMD) is the leading cause of death in patients with sepsis in the intensive care units. The main manifestations of SIMD are systolic and diastolic dysfunctions of the myocardium. Despite our initial understanding of the SIMD over the past three decades, the incidence and mortality of SIMD remain high. This may be attributed to the large degree of heterogeneity among the initiating factors, disease processes, and host states involved in SIMD. Previously, organ dysfunction caused by sepsis was thought to be an impairment brought about by an excessive inflammatory response. However, many recent studies have shown that SIMD is a consequence of a combination of factors shaped by the inflammatory responses between the pathogen and the host. In this article, we review the mechanisms of the inflammatory responses and potential novel therapeutic strategies in SIMD.

Palmitate-Induced Cardiac Lipotoxicity Is Relieved by the Redox-Active Motif of SELENOT through Improving Mitochondrial Function and Regulating Metabolic State

Cardiac lipotoxicity is an important contributor to cardiovascular complications during obesity. Given the fundamental role of the endoplasmic reticulum (ER)-resident Selenoprotein T (SELENOT) for cardiomyocyte differentiation and protection and for the regulation of glucose metabolism, we took advantage of a small peptide (PSELT), derived from the SELENOT redox-active motif, to uncover the mechanisms through which PSELT could protect cardiomyocytes against lipotoxicity. To this aim, we modeled cardiac lipotoxicity by exposing H9c2 cardiomyocytes to palmitate (PA). The results showed that PSELT counteracted PA-induced cell death, lactate dehydrogenase release, and the accumulation of intracellular lipid droplets, while an inert form of the peptide (I-PSELT) lacking selenocysteine was not active against PA-induced cardiomyocyte death. Mechanistically, PSELT counteracted PA-induced cytosolic and mitochondrial oxidative stress and rescued SELENOT expression that was downregulated by PA through FAT/CD36 (cluster of differentiation 36/fatty acid translocase), the main transporter of fatty acids in the heart. Immunofluorescence analysis indicated that PSELT also relieved the PA-dependent increase in CD36 expression, while in SELENOT-deficient cardiomyocytes, PA exacerbated cell death, which was not mitigated by exogenous PSELT. On the other hand, PSELT improved mitochondrial respiration during PA treatment and regulated mitochondrial biogenesis and dynamics, preventing the PA-provoked decrease in PGC1-α and increase in DRP-1 and OPA-1. These findings were corroborated by transmission electron microscopy (TEM), revealing that PSELT improved the cardiomyocyte and mitochondrial ultrastructures and restored the ER network. Spectroscopic characterization indicated that PSELT significantly attenuated infrared spectral-related macromolecular changes (i.e., content of lipids, proteins, nucleic acids, and carbohydrates) and also prevented the decrease in membrane fluidity induced by PA. Our findings further delineate the biological significance of SELENOT in cardiomyocytes and indicate the potential of its mimetic PSELT as a protective agent for counteracting cardiac lipotoxicity.

Quercetin and Its Derivative Counteract Palmitate-Dependent Lipotoxicity by Inhibiting Oxidative Stress and Inflammation in Cardiomyocytes

Cardiac lipotoxicity plays an important role in the pathogenesis of obesity-related cardiovascular disease. The flavonoid quercetin (QUE), a nutraceutical compound that is abundant in the "Mediterranean diet", has been shown to be a potential therapeutic agent in cardiac and metabolic diseases. Here, we investigated the beneficial role of QUE and its derivative Q2, which demonstrates improved bioavailability and chemical stability, in cardiac lipotoxicity. To this end, H9c2 cardiomyocytes were pre-treated with QUE or Q2 and then exposed to palmitate (PA) to recapitulate the cardiac lipotoxicity occurring in obesity. Our results showed that both QUE and Q2 significantly attenuated PA-dependent cell death, although QUE was effective at a lower concentration (50 nM) when compared with Q2 (250 nM). QUE decreased the release of lactate dehydrogenase (LDH), an important indicator of cytotoxicity, and the accumulation of intracellular lipid droplets triggered by PA. On the other hand, QUE protected cardiomyocytes from PA-induced oxidative stress by counteracting the formation of malondialdehyde (MDA) and protein carbonyl groups (which are indicators of lipid peroxidation and protein oxidation, respectively) and intracellular ROS generation, and by improving the enzymatic activities of catalase and superoxide dismutase (SOD). Pre-treatment with QUE also significantly attenuated the inflammatory response induced by PA by reducing the release of key proinflammatory cytokines (IL-1β and TNF-α). Similar to QUE, Q2 (250 nM) also significantly counteracted the PA-provoked increase in intracellular lipid droplets, LDH, and MDA, improving SOD activity and decreasing the release of IL-1β and TNF-α. These results suggest that QUE and Q2 could be considered potential therapeutics for the treatment of the cardiac lipotoxicity that occurs in obesity and metabolic diseases.

Mitochondria-endoplasmic reticulum contacts in sepsis-induced myocardial dysfunction

Mitochondrial and endoplasmic reticulum (ER) are important intracellular organelles. The sites that mitochondrial and ER are closely related in structure and function are called Mitochondria-ER contacts (MERCs). MERCs are involved in a variety of biological processes, including calcium signaling, lipid synthesis and transport, autophagy, mitochondrial dynamics, ER stress, and inflammation. Sepsis-induced myocardial dysfunction (SIMD) is a vital organ damage caused by sepsis, which is closely associated with mitochondrial and ER dysfunction. Growing evidence strongly supports the role of MERCs in the pathogenesis of SIMD. In this review, we summarize the biological functions of MERCs and the roles of MERCs proteins in SIMD.

Omaveloxolone attenuates the sepsis-induced cardiomyopathy via activating the nuclear factor erythroid 2-related factor 2

Sepsis-induced cardiomyopathy (SIC) is a common complication of sepsis and is the main reason for the high mortality in sepsis patients. More recent studies have indicated that activating nuclear factor erythroid 2-related factor 2 (Nrf2) signaling plays a protective role in SIC. As a potent activator of Nrf2, Omaveloxolone plays a pivotal role in defending against oxidative stress and the inflammatory response. Thus, we examined the efficacy of omaveloxolone in SIC. In the present study, the mice were injected intraperitoneally with a single dose of LPS (10 mg/kg) for 12 h to induce SIC. The data in our study indicated that omaveloxolone administration significantly improved cardiac injury and dysfunction in LPS-induced SIC. In addition, omaveloxolone administration reduced SIC-related cardiac oxidative stress, the inflammatory response and cardiomyocyte apoptosis in mice. In addition, omaveloxolone administration also improved LPS-induced cardiomyocyte injury in an in vitro model using H9C2 cells. Moreover, knockdown of Nrf2 by si-Nrf2 abolished the omaveloxolone-mediated cardioprotective effects. In conclusion, omaveloxolone has potent cardioprotective potential in treating sepsis and SIC via activation of the Nrf2 signaling pathway.

The Antioxidant Selenoprotein T Mimetic, PSELT, Induces Preconditioning-like Myocardial Protection by Relieving Endoplasmic-Reticulum Stress

Oxidative stress and endoplasmic reticulum stress (ERS) are strictly involved in myocardial ischemia/reperfusion (MI/R). Selenoprotein T (SELENOT), a vital thioredoxin-like selenoprotein, is crucial for ER homeostasis and cardiomyocyte differentiation and protection, likely acting as a redox-sensing protein during MI/R. Here, we designed a small peptide (PSELT), encompassing the redox site of SELENOT, and investigated whether its pre-conditioning cardioprotective effect resulted from modulating ERS during I/R. The Langendorff rat heart model was employed for hemodynamic analysis, while mechanistic studies were performed in perfused hearts and H9c2 cardiomyoblasts. PSELT improved the post-ischemic contractile recovery, reducing infarct size and LDH release with and without the ERS inducer tunicamycin (TM). Mechanistically, I/R and TM upregulated SELENOT expression, which was further enhanced by PSELT. PSELT also prevented the expression of the ERS markers CHOP and ATF6, reduced cardiac lipid peroxidation and protein oxidation, and increased SOD and catalase activities. An inert PSELT (I-PSELT) lacking selenocysteine was ineffective. In H9c2 cells, H₂O₂ decreased cell viability and SELENOT expression, while PSELT rescued protein levels protecting against cell death. In SELENOT-deficient H9c2 cells, H₂O₂ exacerbated cell death, that was partially mitigated by PSELT. Microscopy analysis revealed that a fluorescent form of PSELT was internalized into cardiomyocytes with a perinuclear distribution. Conclusions: The cell-permeable PSELT is able to induce pharmacological preconditioning cardioprotection by mitigating ERS and oxidative stress, and by regulating endogenous SELENOT.

The Catestatin-Derived Peptides Are New Actors to Fight the Development of Oral Candidosis

Resistance to antifungal therapy of Candida albicans and non-albicans Candida strains, frequently associated with oral candidosis, is on the rise. In this context, host-defense peptides have emerged as new promising candidates to overcome antifungal resistance. Thus, the aim of this study was to assess the effectiveness against Candida species of different Catestatin-derived peptides, as well as the combined effect with serum albumin. Among Catestatin-derived peptides, the most active against sensitive and resistant strains of C. albicans, C. tropicalis and C. glabrata was the D-isomer of Cateslytin (D-bCtl) whereas the efficiency of the L-isomer (L-bCtl) significantly decreases against C. glabrata strains. Images obtained by transmission electron microscopy clearly demonstrated fungal membrane lysis and the leakage of the intracellular material induced by the L-bCtl and D-bCtl peptides. The possible synergistic effect of albumin on Catestatin-derived peptides activity was investigated too. Our finding showed that bovine serum albumin (BSA) when combined with the L- isomer of Catestatin (L-bCts) had a synergistic effect against Candida albicans especially at low concentrations of BSA; however, no synergistic effect was detected when BSA interacted with L-bCtl, suggesting the importance of the C-terminal end of L-bCts (GPGLQL) for the interaction with BSA. In this context in vitro D-bCtl, as well as the combination of BSA with L-bCts are potential candidates for the development of new antifungal drugs for the treatment of oral candidosis due to Candida and non-Candida albicans, without detrimental side effects.

Catestatin in innate immunity and Cateslytin-derived peptides against superbugs

Chromogranin A (CgA) is the precursor of several antimicrobial peptides, such as Catestatin (Cts, bovine CgA344-364), initially described as a potent inhibitor of catecholamines. This peptide displays direct antimicrobial activities and contributes to immune system regulation. The aim of the present study is to investigate a designed peptide based on Cts to fight infections against superbugs and more particularly Staphylococcus aureus. In addition to Cateslytin (Ctl, bovine CgA344-358), the active domain of Catestatin, several peptides including dimers, D-isomer and the new designed peptide DOPA-K-DOPA-K-DOPA-TLRGGE-RSMRLSFRARGYGFR (Dopa5T-Ctl) were prepared and tested. Cateslytin is resistant to bacterial degradation and does not induce bacterial resistance. The interaction of Catestatin with immune dermal cells (dendritic cells DC1a, dermal macrophages CD14 and macrophages) was analyzed by using confocal microscopy and cytokine release assay. The dimers and D-isomer of Ctl were tested against a large variety of bacteria showing the potent antibacterial activity of the D-isomer. The peptide Dopa5T-Ctl is able to induce the self-killing of S. aureus after release of Ctl by the endoprotease Glu-C produced by this pathogen. It permits localized on-demand delivery of the antimicrobial drug directly at the infectious site.

The Emerging Roles of Chromogranins and Derived Polypeptides in Atherosclerosis, Diabetes, and Coronary Heart Disease

Chromogranin A (CgA), B (CgB), and C (CgC), the family members of the granin glycoproteins, are associated with diabetes. These proteins are abundantly expressed in neurons, endocrine, and neuroendocrine cells. They are also present in other areas of the body. Patients with diabetic retinopathy have higher levels of CgA, CgB, and CgC in the vitreous humor. In addition, type 1 diabetic patients have high CgA and low CgB levels in the circulating blood. Plasma CgA levels are increased in patients with hypertension, coronary heart disease, and heart failure. CgA is the precursor to several functional peptides, including catestatin, vasostatin-1, vasostatin-2, pancreastatin, chromofungin, and many others. Catestatin, vasostain-1, and vasostatin-2 suppress the expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 in human vascular endothelial cells. Catestatin and vasostatin-1 suppress oxidized low-density lipoprotein-induced foam cell formation in human macrophages. Catestatin and vasostatin-2, but not vasostatin-1, suppress the proliferation and these three peptides suppress the migration in human vascular smooth muscles. Chronic infusion of catestatin, vasostatin-1, or vasostatin-2 suppresses the development of atherosclerosis of the aorta in apolipoprotein E-deficient mice. Catestatin, vasostatin-1, vasostatin-2, and chromofungin protect ischemia/reperfusion-induced myocardial dysfunction in rats. Since pancreastatin inhibits insulin secretion from pancreatic β-cells, and regulates glucose metabolism in liver and adipose tissues, pancreastatin inhibitor peptide-8 (PSTi8) improves insulin resistance and glucose homeostasis. Catestatin stimulates therapeutic angiogenesis in the mouse hind limb ischemia model. Gene therapy with secretoneurin, a CgC-derived peptide, stimulates postischemic neovascularization in apolipoprotein E-deficient mice and streptozotocin-induced diabetic mice, and improves diabetic neuropathy in db/db mice. Therefore, CgA is a biomarker for atherosclerosis, diabetes, hypertension, and coronary heart disease. CgA- and CgC--derived polypeptides provide the therapeutic target for atherosclerosis and ischemia-induced tissue damages. PSTi8 is useful in the treatment of diabetes.