4-Octyl Itaconate Research Articles

Itaconate suppresses atherosclerosis by activating a Nrf2-dependent antiinflammatory response in macrophages in mice.

Itaconate has emerged as a critical immunoregulatory metabolite. Here, we examined the therapeutic potential of itaconate in atherosclerosis. We found that both itaconate and the enzyme that synthesizes it, aconitate decarboxylase 1 (Acod1, also known as immune-responsive gene 1 [IRG1]), are upregulated during atherogenesis in mice. Deletion of Acod1 in myeloid cells exacerbated inflammation and atherosclerosis in vivo and resulted in an elevated frequency of a specific subset of M1-polarized proinflammatory macrophages in the atherosclerotic aorta. Importantly, Acod1 levels were inversely correlated with clinical occlusion in atherosclerotic human aorta specimens. Treating mice with the itaconate derivative 4-octyl itaconate attenuated inflammation and atherosclerosis induced by high cholesterol. Mechanistically, we found that the antioxidant transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2), was required for itaconate to suppress macrophage activation induced by oxidized lipids in vitro and to decrease atherosclerotic lesion areas in vivo. Overall, our work shows that itaconate suppresses atherogenesis by inducing Nrf2-dependent inhibition of proinflammatory responses in macrophages. Activation of the itaconate pathway may represent an important approach to treat atherosclerosis.

4-octyl itaconate ameliorates ventilator-induced lung injury

Ventilator-induced lung injury (VILI) disturbs the disordered immune system and causes persistent inflammatory damage. 4-octyl itaconate (OI) is a synthetic cell-permeable itaconate derivative with antioxidant and anti-inflammatory effects. In this study, we assessed whether OI protects against VILI. OI was intraperitoneally injected for three days before mechanical ventilation (MV; 20 ml/kg at 70 breaths/min) for 2 h. Mouse lung vascular endothelial cells (MLVECs) were pretreated with OI (62.5, 125, and 250 μM) prior to cyclic stretch for 4 h. We found that OI attenuated VILI and inflammatory response. OI also increased superoxide dismutase, nuclear factor E2-related factor 2, and heme oxygenase-1 levels, and decreased reactive oxygen species and malondialdehyde levels. Furthermore, OI inhibited the expression of NLR family pyrin domain-containing 3 (NLRP3), caspase-1 p20, apoptosis-associated speck-like protein containing a CARD, and N-terminal fragment of gasdermin D. Therefore, OI attenuates VILI, potentially by suppressing oxidative stress and NLRP3 activation.

4-Octyl itaconate alleviates experimental autoimmune prostatitis by inhibiting the NLRP3 inflammasome-induced pyroptosis through activating Nrf2/HO-1 pathway.

Chronic prostatitis demonstrates a prevalence rate of nearly 5%-10% among young and middle-aged individuals, significantly affecting their daily lives. Researchers have obtained significant outcomes investigating the anti-inflammatory properties of itaconic acid (IA) and its derivative, 4-Octyl itaconate (4-OI), against diverse chronic inflammatory disorders, such as osteoarthritis and airway inflammation. Nevertheless, whether IA can also exert anti-inflammatory effects in chronic prostatitis requires extensive research and validation. Human prostate tissues obtained through transurethral prostate resection (TURP) from individuals were divided into three groups based on different levels of inflammation using hematoxylin and eosin staining (H&E). Subsequently, immunohistochemistry (IHC) was employed to detect the expression of immune-responsive gene 1 (IRG-1) in these different groups. The animal experiment of this study induced experimental autoimmune prostatitis (EAP) in nonobese diabetic mice through intradermal prostate antigen injection and complete Freund's adjuvant. Then, the experimental group received intraperitoneal injections of different doses of 4-OI, while the control group received injections of saline. Western blot (WB), H&E staining, and TUNEL staining helped analyze the prostate tissues, while enzyme-linked immunosorbent assay (ELISA) helped evaluate serum inflammatory factors. Reactive oxygen species, superoxide dismutase (SOD), and malondialdehyde (MDA) were assessed for oxidative stress across experimental groups. IHC analysis of human prostate tissue depicts that IRG-1 expression enhances as prostate inflammation worsens, highlighting the critical role of IA in human prostatitis. The application of 4-OI increased Nrf2/HO-1 expression while inhibited NLRP3 expression following the WB results, and its application resulted in a decrease in cell pyroptosis in prostate tissue, demonstrated by the results of TUNEL staining. Administering a Nrf2 inhibitor ML385 1 h before intraperitoneal injection of 50 mg/kg 4-OI reversed the previous conclusion, further confirming the above conclusion from another perspective. Meanwhile, the ELISA results of serum inflammatory factors (IL-1β, IL-6, and TNF-α), as well as the measurements of oxidative stress markers MDA and SOD, further confirmed the specific anti-inflammatory effects of 4-OI in EAP. The present study indicates that 4-OI can alleviates EAP by inhibiting the NLRP3 inflammasome-induced pyroptosis through activating Nrf2/HO-1 pathway, which may facilitate a novel approach toward prostatitis treatment.

4-Octyl itaconate inhibits poly(I:C)-induced interferon-β secretion in mouse bone marrow-derived macrophages partially by activating Nrf2

Viruses have become a major threat to human health. Interferon-β (IFN-β) has a key role in the antivirus process, as it can increase the expression of antivirus-associated genes. Itaconate and its derivatives can regulate the immune response, secretion of inflammatory factors, and pyroptosis of macrophages. The effect of itaconate on IFN-β secretion of double-stranded RNA-induced macrophages are not well known. A derivative of itaconate, 4-octoyl itaconate (4-OI), was used to treat mouse bone marrow-derived macrophages (BMDM) induced with 100 μg/mL poly(I:C). The IFN-β concentration was detected through ELISA, and IFN-β mRNA expression was detected through quantitative PCR. High-throughput transcriptome sequencing was used to analyze changes in the BMDM transcriptome after 4-OI treatment. The Nrf2 expression was knocked down with siRNA.4-OI inhibited poly(I:C)-induced IFN-β secretion and mRNA expression in BMDM. Results of transcriptome sequencing revealed that 4-OI downregulated 1047 genes and upregulated 822 genes. GO and KEGG enrichment of differently expressed genes revealed that many downregulated genes were related to the anti-virus process, whereas many upregulated genes were related to metabolism. The Nrf2 inhibitor ML385 and Nrf2 siRNA could partially reverse the inhibitory effect of 4-OI. In conclusion, 4-octyl itaconate could inhibit the poly(I:C)-induced interferon-β secretion in BMDM partially by regulating Nrf2.

4-Octyl Itaconate Alleviates Airway Eosinophilic Inflammation by Suppressing Chemokines and Eosinophil Development.

4-Octyl itaconate (4-OI) is a derivative of the Krebs cycle-derived metabolite itaconate and displays an array of antimicrobial and anti-inflammatory properties through modifying cysteine residues within protein targets. We have found that 4-OI significantly reduces the production of eosinophil-targeted chemokines in a variety of cell types, including M1 and M2 macrophages, Th2 cells, and A549 respiratory epithelial cells. Notably, the suppression of these chemokines in M1 macrophages was found to be NRF2-dependent. In addition, 4-OI can interfere with IL-5 signaling and directly affect eosinophil differentiation. In a model of eosinophilic airway inflammation in BALB/c mice, 4-OI alleviated airway resistance and reduced eosinophil recruitment to the lungs. Our findings suggest that itaconate derivatives could be promising therapeutic agents for the treatment of eosinophilic asthma.

4-Octyl itaconate reduces influenza A replication by targeting the nuclear export protein CRM1.

Itaconate derivates, as well as the naturally produced metabolite, have been proposed as antivirals against influenza virus. Here, the mechanism behind the antiviral effects of exogenous 4-octyl itaconate (4-OI), a derivative of itaconate, against the influenza A virus replication is demonstrated. The data indicate that 4-OI targets the cysteine at position 528 of the CRM1 protein, resulting in inhibition of the nuclear export of viral ribonucleoprotein complexes in a similar manner as previously described for other selective inhibitors of nuclear export. These results postulate a mechanism not observed before for this immuno-metabolite derivative. This knowledge is helpful for the development of derivatives of 4-OI as potential antiviral and anti-inflammatory therapeutics.

Bioinspired nanovesicles released from injectable hydrogels facilitate diabetic wound healing by regulating macrophage polarization and endothelial cell dysfunction

Wound healing is one of the major global health concerns in diabetic patients. Overactivation of proinflammatory M1 macrophages could lead to delayed wound healing in diabetes. 4-octyl itaconate (4OI), a derivative of the metabolite itaconate, has aroused growing interest recently on account of its excellent anti-inflammatory properties. Cell membrane coating is widely regarded as a novel biomimetic strategy to deliver drugs and inherit properties derived from source cells for biomedical applications. Herein, we fused induced pluripotent stem cell-derived endothelial cell (iEC) membrane together with M1 type macrophage membrane to construct a hybrid membrane (iEC-M) camouflaged 4OI nanovesicles (4OI@iEC-M). Furthermore, bioinspired nanovesicles 4OI@iEC-M are incorporated into the injectable, multifunctional gelatin methacryloyl hydrogels for diabetic wound repair and regeneration. In our study, bioinspired nanovesicles could achieve dual-targeted deliver of 4OI into both M1 macrophages and endothelial cells, thereby promoting macrophage polarization and protecting endothelial cells. With the synergistically anti-inflammatory and immunoregulative effects, the bioinspired nanovesicles-loaded hydrogels could facilitate neovascularization and exhibit superior diabetic wound repair and regeneration. Taken together, this study might provide a novel strategy to facilitate diabetic wound healing, thereby reducing limb amputation and mortality of diabetes.

OC 55.2 Dimethyl Fumarate and 4-Octyl Itaconate are Anticoagulants that Suppress Tissue Factor in Macrophages Via Inhibition of Type I Interferon

OC 55.2 Dimethyl Fumarate and 4-Octyl Itaconate are Anticoagulants that Suppress Tissue Factor in Macrophages Via Inhibition of Type I Interferon

237.3: 4-Octyl itaconate reverses metabolic reprogramming of T cells in aGVHD by partial inhibition of GAPDH

237.3: 4-Octyl itaconate reverses metabolic reprogramming of T cells in aGVHD by partial inhibition of GAPDH

4-Octyl itaconate inhibits inflammation to attenuate psoriasis as an agonist of oxeiptosis

Psoriasis is a highly prevalent chronic disease associated with a substantial social and economic burden. Oxeiptosis is a programmed cell death that occurs when cells are in a state of high oxidative stress, which has a potent anti-inflammatory effect. However, there is still no research on oxeiptosis in psoriasis, and the agonists or antagonists of oxeiptosis remain an unclear field. Here, we found that oxeiptosis of keratinocytes was inhibited in psoriasis lesions. KEAP1, as the upstream molecular component of oxeiptosis, is highly expressed in psoriasis lesions. Knockdown of KEAP1 in HaCaT cells caused oxeiptosis in the condition of M5 cocktail stimulation. Next, we found that the cell-permeable derivative of itaconate, 4-octylitaconate (OI) promoted oxeiptosis of keratinocytes by inhibiting KEAP1 and then activating PGAM5 which are two upstream molecular components of oxeiptosis. At the same time, OI can reduce the expression of inflammatory cytokines induced by M5 cocktail stimulation in vitro. Similarly, we found that OI can alleviate IMQ-induced psoriatic lesions in mice and downregulate the levels of inflammatory cytokines in psoriatic lesions. In summary, our findings suggest that oxeiptosis of keratinocytes was inhibited in psoriasis and OI can significantly inhibit inflammation and alleviate psoriasis as an agonist of oxeiptosis, indicating that oxeiptosis may be involved in regulating the progression of psoriasis, which may provide new therapeutic targets for psoriasis treatment.

Microglia-dependent neuroprotective effects of 4-octyl itaconate against rotenone-and MPP+-induced neurotoxicity in Parkinson’s disease

Chronic neuroinflammation is implicated in the pathogenesis of Parkinson’s disease (PD), one of the most common neurodegenerative diseases. Itaconate, an endogenous metabolite derived from the tricarboxylic acid cycle via immune‐responsive gene 1 activity, may mediate anti-inflammatory responses by activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway. This study investigates the neuroprotective potential of 4-octyl itaconate (OI), a cell-permeable derivative of itaconate, in cellular models of PD. OI not only suppressed lipopolysaccharide-induced proinflammatory cascades of inducible nitric oxide synthase, cyclooxygenase-2, and cytokines release in mouse BV2 microglial cells but also activated the Nrf2 signaling pathway and its downstream targets in these cells. Conditioned medium derived from OI-treated BV2 cells protected against rotenone- and MPP+-induced neurotoxicity in Neuro 2A cells. Overall, our findings support the anti-inflammatory neuroprotective potential of OI in PD.

Nrf2 inhibition increases sensitivity to chemotherapy of colorectal cancer by promoting ferroptosis and pyroptosis

Oxaliplatin is widely used in chemotherapy for colorectal cancer (CRC), but its sensitivity has become a major obstacle to limiting efficacy. Many literatures reported that Nrf2 activation promoted tumor chemoresistance. In this study, we explored the role and mechanism of Nrf2 inhibition in oxaliplatin-based chemosensitivity of CRC. In vitro experiments, we applied 4-octyl itaconate (4-OI) to activate Nrf2, and used lentivirus to knock down Nrf2 in CRC cell lines. By measuring cell viability, colony formation, apoptosis, reactive oxygen species production, and western blot, we found that oxaliplatin and lobaplatin suppressed the growth of HCT-116 and LOVO cells in a dose-dependent manner, and promoted the expression of Nrf2. 4-OI, an Nrf2 activator, reduced the sensibility of CRC cells to oxaliplatin and lobaplatin, while the knockdown of Nrf2 promoted the sensibility of CRC cells to oxaliplatin and lobaplatin. Through the public databases, we found that the expression of GPX4 in normal tissues was lower compared with cancer tissues in CRC, and the high GPX4 expression predicted a poor prognosis. Meanwhile, we found that oxaliplatin reduced the expression of GPX4 in vitro. The knockdown of Nrf2 enhanced the effects of oxaliplatin to reduce the expression of GPX4 and GSH content, and increase the MDA content, which enhanced oxaliplatin-induced ferroptosis. Subsequently, we found that oxaliplatin promoted the expression of GSDME-N, and induced LDH, IL-1β, and TNF-a release, and the knockdown of Nrf2 aggravated the occurrence of GSMDE-mediated pyroptosis. Finally, we found that the knockdown of Nrf2 enhanced the inhibition of oxaliplatin on HCT116 xenograft tumor growth in vivo. Thus, our study showed that Nrf2 inhibition improved sensitivity to oxaliplatin of CRC cells by promoting ferroptosis and pyroptosis, which provided a new target for overcoming chemoresistance in CRC.

4-Octyl itaconate restricts STING activation by blocking its palmitoylation

The cyclic guanosine monophosphate adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) axis plays a vital role in defending foreign pathogens and maintaining immune homeostasis. While substantial advances have been made in understanding the metabolic changes that occur during macrophage activation, little is known about how these metabolic changes affect the cGAS-STING axis. In this study, we identify that 4-octyl itaconate (4-OI), a derivative of itaconate, inhibits the activation of cGAS-STING. Furthermore, we show that 4-OI inhibits cGAS-STING-related antiviral immune responses and autoimmune inflammation. However, we find that endogenous itaconate does not affect cGAS-STING activation, indicating that 4-OI and itaconate function differently. Mechanistically, we find that 4-OI directly alkylates STING at Cys91, blocking STING palmitoylation and oligomerization. The alkylation of STING by 4-OI represents another type of post-translational modifications (PTMs) of STING. Our findings reveal a mechanism by which cGAS-STING function is regulated through 4-OI alkylation and provide insights into the crosstalk between different kinds of PTMs.

4-Octyl Itaconate and Dimethyl Fumarate Induce Secretion of the Anti-Inflammatory Protein Annexin A1 via NRF2.

Annexin A1 is a key anti-inflammatory effector protein that is involved in the anti-inflammatory effects of glucocorticoids. 4-Octyl itaconate (4-OI), a derivative of the endogenous metabolite itaconate, which is abundantly produced by LPS-activated macrophages, has recently been identified as a potent anti-inflammatory agent. The anti-inflammatory effects of 4-OI share a significant overlap with those of dimethyl fumarate (DMF), a derivate of another Krebs cycle metabolite fumarate, which is already in use clinically for the treatment of inflammatory diseases. In this study we show that both 4-OI and DMF induce secretion of the 33-kDa form of annexin A1 from murine bone marrow-derived macrophages, an effect that is much more pronounced in LPS-stimulated cells. We also show that this 4-OI- and DMF-driven annexin A1 secretion is NRF2-dependent and that other means of activating NRF2 give rise to the same response. Lastly, we demonstrate that the cholesterol transporter ABCA1, which has previously been implicated in annexin A1 secretion, is required for this process in macrophages. Our findings contribute to the growing body of knowledge on the anti-inflammatory effects of the Krebs cycle metabolite derivatives 4-OI and DMF.

Negative regulation of pro-apoptotic AMPK/JNK pathway by itaconate in mice with fulminant liver injury

Accumulating evidence indicates that metabolic responses are deeply integrated into signal transduction, which provides novel opportunities for the metabolic control of various disorders. Recent studies suggest that itaconate, a highly concerned bioactive metabolite catalyzed by immune responsive gene 1 (IRG1), is profoundly involved in the regulation of apoptosis, but the underlying mechanisms have not been fully understood. In the present study, the molecular mechanisms responsible for the apoptosis-modulatory activities of IRG1/itaconate have been investigated in mice with lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced apoptotic liver injury. The results indicated that LPS/D-Gal exposure upregulated the level of IRG1 and itaconate. Deletion of IRG1 resulted in exacerbated hepatocytes apoptosis and liver injury. The phospho-antibody microarray analysis and immunoblot analysis indicated that IRG1 deletion enhanced the activation of AMP-activated protein kinase (AMPK)/c-jun-N-terminal kinase (JNK) pathway in LPS/D-Gal exposed mice. Mechanistically, IRG1 deficiency impaired the anti-oxidative nuclear factor erythroid-2 related factor 2 (Nrf2) signaling and then enhanced the activation of the redox-sensitive AMPK/JNK pathway that promotes hepatocytes apoptosis. Importantly, post-insult supplementation with 4-octyl itaconate (4-OI), a cell-permeable derivate of itaconate, resulted in beneficial outcomes in fulminant liver injury. Therefore, IRG1/itaconate might function as a negative regulator that controls AMPK-induced hepatocyte apoptosis in LPS/D-Gal-induced fulminant liver injury.

Itaconate inhibits CD103 + T RM cells and alleviates hepatobiliary injury in mouse models of primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is a chronic progressive liver disease characterized by the infiltration of intrahepatic tissue-resident memory CD8 + T cells (T RM ). Itaconate has demonstrated therapeutic potential in modulating inflammation. An unmet need for PSC is the reduction of biliary inflammation, and we hypothesized that itaconate may directly modulate pathogenic T RM . The numbers of intrahepatic CD103 + T RM were evaluated by immunofluorescence in PSC (n = 32), and the serum levels of itaconate in PSC (n = 64), primary biliary cholangitis (PBC) (n = 60), autoimmune hepatitis (AIH) (n = 49), and healthy controls (n = 109) were determined by LC-MS/MS. In addition, the frequencies and immunophenotypes of intrahepatic T RM using explants from PSC (n = 5) and healthy donors (n = 6) were quantitated by flow cytometry. The immunomodulatory properties of 4-octyl itaconate (4-OI, a cell-permeable itaconate derivative) on CD103 + T RM were studied in vitro. Finally, the therapeutic potential of itaconate was studied by the administration of 4-OI and deficiency of immune-responsive gene 1 (encodes the aconitate decarboxylase producing itaconate) in murine models of PSC. Intrahepatic CD103 + T RM was significantly expanded in PSC and was positively correlated with disease severity. Serum itaconate levels decreased in PSC. Importantly, 4-OI inhibited the induction and effector functions of CD103 + T RM in vitro. Mechanistically, 4-OI blocked DNA demethylation of RUNX3 in CD8 + T cells. Moreover, 4-OI reduced intrahepatic CD103 + T RM and ameliorated liver injury in murine models of PSC. Itaconate exerted immunomodulatory activity on CD103 + T RM in both in vitro and murine PSC models. Our study suggests that targeting pathogenic CD103 + T RM with itaconate has therapeutic potential in PSC.

NRF2 activators inhibit influenza A virus replication by interfering with nucleo-cytoplasmic export of viral RNPs in an NRF2-independent manner.

In addition to antioxidative and anti-inflammatory properties, activators of the cytoprotective nuclear factor erythroid-2-like-2 (NRF2) signaling pathway have antiviral effects, but the underlying antiviral mechanisms are incompletely understood. We evaluated the ability of the NRF2 activators 4-octyl itaconate (4OI), bardoxolone methyl (BARD), sulforaphane (SFN), and the inhibitor of exportin-1 (XPO1)-mediated nuclear export selinexor (SEL) to interfere with influenza virus A/Puerto Rico/8/1934 (H1N1) infection of human cells. All compounds reduced viral titers in supernatants from A549 cells and vascular endothelial cells in the order of efficacy SEL>4OI>BARD = SFN, which correlated with their ability to prevent nucleo-cytoplasmic export of viral nucleoprotein and the host cell protein p53. In contrast, intracellular levels of viral HA mRNA and nucleocapsid protein (NP) were unaffected. Knocking down mRNA encoding KEAP1 (the main inhibitor of NRF2) or inactivating the NFE2L2 gene (which encodes NRF2) revealed that physiologic NRF2 signaling restricts IAV replication. However, the antiviral effect of all compounds was NRF2-independent. Instead, XPO1 knock-down greatly reduced viral titers, and incubation of Calu3 cells with an alkynated 4OI probe demonstrated formation of a covalent complex with XPO1. Ligand-target modelling predicted covalent binding of all three NRF2 activators and SEL to the active site of XPO1 involving the critical Cys528. SEL and 4OI manifested the highest binding energies, whereby the 4-octyl tail of 4OI interacted extensively with the hydrophobic groove of XPO1, which binds nuclear export sequences on cargo proteins. Conversely, SEL as well as the three NRF2 activators were predicted to covalently bind the functionally critical Cys151 in KEAP1. Blocking XPO1-mediated nuclear export may, thus, constitute a "noncanonical" mechanism of anti-influenza activity of electrophilic NRF2 activators that can interact with similar cysteine environments at the active sites of XPO1 and KEAP1. Considering the importance of XPO1 function to a variety of pathogenic viruses, compounds that are optimized to inhibit both targets may constitute an important class of broadly active host-directed treatments that embody anti-inflammatory, cytoprotective, and antiviral properties.

Dimethyl fumarate and 4-octyl itaconate are anticoagulants that suppress Tissue Factor in macrophages via inhibition of Type I Interferon

Excessive inflammation-associated coagulation is a feature of infectious diseases, occurring in such conditions as bacterial sepsis and COVID-19. It can lead to disseminated intravascular coagulation, one of the leading causes of mortality worldwide. Recently, type I interferon (IFN) signaling has been shown to be required for tissue factor (TF; gene name F3) release from macrophages, a critical initiator of coagulation, providing an important mechanistic link between innate immunity and coagulation. The mechanism of release involves type I IFN-induced caspase-11 which promotes macrophage pyroptosis. Here we find that F3 is a type I IFN-stimulated gene. Furthermore, F3 induction by lipopolysaccharide (LPS) is inhibited by the anti-inflammatory agents dimethyl fumarate (DMF) and 4-octyl itaconate (4-OI). Mechanistically, inhibition of F3 by DMF and 4-OI involves suppression of Ifnb1 expression. Additionally, they block type I IFN- and caspase-11-mediated macrophage pyroptosis, and subsequent TF release. Thereby, DMF and 4-OI inhibit TF-dependent thrombin generation. In vivo, DMF and 4-OI suppress TF-dependent thrombin generation, pulmonary thromboinflammation, and lethality induced by LPS, E. coli, and S. aureus, with 4-OI additionally attenuating inflammation-associated coagulation in a model of SARS-CoV-2 infection. Our results identify the clinically approved drug DMF and the pre-clinical tool compound 4-OI as anticoagulants that inhibit TF-mediated coagulopathy via inhibition of the macrophage type I IFN-TF axis.

4-OCTYL ITACONATE ATTENUATES ISOPROTERENOL INDUCED MYOCARDIAL DAMAGE VIA NLRP3 INFLAMMASOME PATHWAY, NRF-2/HO-1 AND MAPK PATHWAY IN AN EXPERIMENTAL MODEL

Objective: Myocardial infarction (MI) is the major cause of morbidity and mortality worldwide. According to the World Health Organisation, more than 9 million deaths occurred due to ischemic heart disease worldwide in 2016. 4-octyl itaconate (4-OI) is a cell permeable derivative of itaconate with potent anti-oxidative, anti-inflammatory and anti-fibrotic properties. Studies have shown that 4-OI inhibits pro-inflammatory cytokines (IL6, IL1beta, TNF alpha) and activates the anti-oxidant Nrf-2/HO-1 pathway. The aim of the study was to investigate the cardio-protective effect of 4-OI in experimental model of Isoproterenol induced myocardial damage. Design and method: Adult male albino wistar rats were used in the study. They were randomly divided to five groups i.e., normal control group, isoproterenol control group, 4-OI group (2.5, 5 or 10 mg/kg) for 14 days and 4-OI perse group. On the 15th day, rats were anaesthetized and right coronary artery was cannulated to record hemodynamic parameters. Following this, blood was withdrawn using cardiac puncture, heart was excised and preserved for analysis of biochemical, histopathological and molecular pathway studies. Results: Isoproterenol administration to rats resulted in induction of Myocardial damage as shown by impairment in hemodynamic parameters, left ventricular dysfunction and raised cardiac injury markers. Treatment with 4-OI significantly improved hemodynamic and cardiac injury markers (CKMB, LDH). Further, 4OI significantly reduced oxidative stress (enhanced levels of SOD, GSH, decreased MDA levels) and inflammation (reduced levels of TNF alpha, IL-6, IL-1beta and NLRP3). Further it activated the Nrf-2-HO-1 pathway while inhibits the inflammatory NFKB pathway. Apart from this, it also ameliorated apoptosis by decreasing the expression of Bax, caspase-3 and increasing the expression of anti-apoptotic Bcl-2. It also inhibited inflammatory MAPK proteins (JNK, phospho JNK, P38, phospho P38) while enhancing the expression of pro-survival kinases ERK1/2, and Phospho ERK1/ 2. Conclusions: Oral administration of 4-OI at a dose of 10 mg/kg ameliorated the severity of isoprotorenol-induced cardio-toxicity in rats via NLRP-3 inflammasome pathway, MAPK and Nrf-2/HO1 pathway and by maintaining morphological structure of heart tissue and oxidative stress profile along with reduced inflammation and apoptosis.

Itaconic acid underpins hepatocyte lipid metabolism in non-alcoholic fatty liver disease in male mice

Itaconate, the product of the decarboxylation of cis-aconitate, regulates numerous biological processes. We and others have revealed itaconate as a regulator of fatty acid β-oxidation, generation of mitochondrial reactive oxygen species and the metabolic interplay between resident macrophages and tumors. In the present study, we show that itaconic acid is upregulated in human non-alcoholic steatohepatitis and a mouse model of non-alcoholic fatty liver disease. Male mice deficient in the gene responsible for itaconate production (immunoresponsive gene (Irg)-1) have exacerbated lipid accumulation in the liver, glucose and insulin intolerance and mesenteric fat deposition. Treatment of mice with the itaconate derivative, 4-octyl itaconate, reverses dyslipidemia associated with high-fat diet feeding. Mechanistically, itaconate treatment of primary hepatocytes reduces lipid accumulation and increases their oxidative phosphorylation in a manner dependent upon fatty acid oxidation. We propose a model whereby macrophage-derived itaconate acts in trans upon hepatocytes to modulate the liver’s ability to metabolize fatty acids.