Bioinspired Multifunctional Black Phosphorus Hydrogel with Antibacterial and Antioxidant Properties: A Stepwise Countermeasure for Diabetic Skin Wound Healing

Cutaneous wound healing, especially diabetic wound healing, is a common clinical challenge. Reactive oxygen species (ROS) and bacterial infection are two major detrimental states that induce oxidative stress and inflammatory responses and impede angiogenesis and wound healing. A derivative of the metabolite itaconate, 4-octyl itaconate (4OI) has attracted increasing research interest in recent years due to its antioxidant and anti-inflammatory properties. In this study, 4OI-modified black phosphorus (BP) nanosheets are incorporated into a photosensitive, multifunctional gelatin methacrylamide hydrogel to produce a new photothermal therapy (PTT) and photodynamic therapy (PDT) system with antibacterial and antioxidant properties for diabetic wound regeneration. Under laser irradiation, the 4OI-BP-entrapped hydrogel enables rapid gelation, forming a membrane on wounds, and offers high PTT and PDT efficacy to eliminate bacterial infection. Without laser irradiation, BP acts as a carrier and controls the release of 4OI, with which it synergistically enhances antioxidant activity, thus alleviating excessive ROS damage to endothelial cells, promoting neovascularization, and facilitating faster diabetic wound closure. These findings indicate that 4OI-BP-entrapped multifunctional hydrogel provides a stepwise countermeasure with antibacterial and antioxidant properties for enhanced diabetic wound healing and may lead to novel therapeutic interventions for diabetic ulcers.

Activation of Keap1-Nrf2 signaling by 4-octyl itaconate protects human umbilical vein endothelial cells from high glucose

High glucose (HG) induces oxidative injury to cultured human umbilical vein endothelial cells (HUVECs). Recent studies have discovered 4-octyl itaconate (OI) as a novel and cell permeable Nrf2 (nuclear-factor-E2-related factor 2) activator. Its potential activity in HG-treated HUVECs was tested here. In HUVECs OI disrupted Keap1-Nrf2 association, causing Nrf2 protein accumulation and nuclear translocation, as well as transcription and expression of Nrf2-ARE-dependent genes, including HO1, NQO1 and GCLM. Significantly, pretreatment with OI potently inhibited HG (40 mM glucose)-induced death and apoptosis of HUVECs. Moreover, OI potently inhibited HG-induced reactive oxygen species (ROS) production, lipid peroxidation, superoxide accumulation and mitochondrial depolarization in HUVECs. Activation of Nrf2 is required for OI-induced cytoprotection in HUVECs. Nrf2 shRNA or knockout (by CRISPR/Cas9 method) reversed OI-mediated HUVEC protection against HG. Further studies showed that Keap1 silencing or Cys151S mutation mimicked and nullified OI-induced activity in HUVECs. Taken together, we conclude that OI activates Keap1-Nrf2 signaling to protect HUVECs from HG.

4-OI Attenuates Carbon Tetrachloride-Induced Hepatic Injury via Regulating Oxidative Stress and the Inflammatory Response

The liver is an important metabolic organ, and acute liver injury (ALI) is potentially lethal. Itaconate, a metabolic intermediate from the tricarboxylic acid cycle, showed emerging anti-oxidative and anti-inflammation properties, and an accumulating protective effect in multiple diseases, but its role in ALI still needs to be further explored. Here we established an ALI model induced by carbon tetrachloride in mice. Our results showed that 4-Octyl itaconate (OI), a derivate of itaconate, mitigated hepatic damage by improving liver function, reducing histopathological damage, and decreasing the death of hepatocytes. Additionally, OI decreased myeloperoxidase and thiobarbituric acid reactive substances (TBARS) levels in the ALI model. OI also inhibited the inflammatory response by reducing pro-inflammatory cytokine secretion (IL-6, TNF-α, IL-1β, and MCP-1) and infiltration of macrophages and neutrophils in the ALI model. However, administration of ML385, a specified Nrf2 inhibitor, eliminated the protective properties of OI in the CCl4-induced liver injury model by increasing hepatic damage and oxidative stress. Furthermore, OI increased the expression and nuclear translocation of Nrf2 and elevated the expression of heme oxygenase-1 and NAD(P)H quinone oxidoreductase 1, while knockdown of Nrf2 eliminated these effects in murine hepatocyte NCTC 1469 under CCl4 treatment. Moreover, we found that OI reduced serum High-mobility group box 1 (HMGB1) levels in CCl4-treated mice. Finally, OI inhibited nuclear translocation of factor-kappa B (NF-𝜅B) and inflammatory cytokine production in murine macrophages. In conclusion, these results indicated that OI ameliorated CCl4-induced ALI by mitigating oxidative stress and the inflammatory response. The possible mechanism was associated with the elevation of Nrf2 nuclear translocation and inhibition of HMGB1 mediated the nuclear translocation of NF-𝜅B.

4-Octyl itaconate (4-OI) attenuates lipopolysaccharide-induced acute lung injury by suppressing PI3K/Akt/NF-κB signaling pathways in mice

The progression of acute lung injury (ALI) is attributable to inflammation and oxidative stress. The cell-permeable itaconate analog 4-octyl itaconate (4-OI) provides protection against inflammatory responses and oxidative stress. However, whether 4-OI can protect against ALI remains poorly understood. The aim of this study was to explore the protective effects of 4-OI against LPS-induced ALI and the underlying mechanisms using hematoxylin and eosin (H&E) to observe lung morphology, ELISA and reverse transcription-quantitative PCR to measure the levels of IL-1β, TNF-α and IL-6 and western blotting to examine the levels of PI3K, Akt and NF-κB. The present study demonstrates that intraperitoneal administration of 4-OI (25 mg/kg) 2 h before lipopolysaccharide (LPS; 5 mg/kg) intratracheal injection significantly alleviated the lung tissue injury induced by LPS, reducing the production of proinflammatory cytokines and reactive oxygen species (ROS) in vivo. Furthermore, 4-OI and the antioxidant N-acetyl-L-cysteine markedly suppressed PI3K and Akt phosphorylation in LPS-treated RAW264.7 macrophage cells in vitro. Further study demonstrated that a pharmacological inhibitor of the phosphoinositide 3-kinase (PI3K)-Akt pathway, LY294002, inhibited the expression of NF-κB p65 in the nuclear fraction and decreased the production of inflammatory cytokines. Collectively, the experimental results of the present study provide evidence that 4-OI significantly decreased LPS-induced lung inflammation by suppressing ROS-mediated PI3K/Akt/NF-κB signaling pathways. These results suggest that 4-OI could be a valuable therapeutic drug in the treatment of ALI.

4-Octyl itaconate attenuates LPS-induced acute kidney injury by activating Nrf2 and inhibiting STAT3 signaling

BACKGROUND

Septic acute kidney injury (S-AKI) is the leading form of acute kidney failure among hospitalized patients, and the inflammatory response is involved in this process. 4-octyl itaconate (4-OI) is a multi-target itaconate derivative with potent anti-inflammatory action. However, it remains elusive whether and how 4-OI contributes to the regulation of S-AKI.

METHODS

We employed a lipopolysaccharide (LPS)-induced AKI murine model and explored the potential renoprotective effect of 4-OI in vivo. In vitro experiments, BUMPT cells, a murine renal tubular cell line, were conducted to examine the effects of 4-OI on inflammation, oxidative stress, and mitophagy. Moreover, STAT3 plasmid was transfected in BUMPT cells to investigate the role of STAT3 signaling in the 4-OI-administrated state.

RESULTS

We demonstrate that 4-OI protects against S-AKI through suppressing inflammation and oxidative stress and enhancing mitophagy. 4-OI significantly reduced the levels of Scr, BUN, Ngal as well as the tubular injury in LPS-induced AKI mice. 4-OI restrained inflammation by reducing macrophage infiltration and suppressing the expression of IL-1β and NLRP3 in the septic kidney. 4-OI also reduced ROS levels, as well as cleaved caspase-3 and boosted antioxidants such as HO-1, and NQO1 in mice. In addition, the 4-OI treatment significantly promoted mitophagy. Mechanistically, 4-OI activated Nrf2 signaling and suppressed phosphorylated STAT3 in vivo and vitro. Molecular docking revealed the binding affinity of 4-OI towards STAT3. ML385, a specific Nrf2 inhibitor, partially repressed the anti-inflammatory and anti-oxidative effects of 4-OI and partially restricted the mitophagy induced by 4-OI in vivo and in vitro. Transfected with STAT3 plasmid partially suppressed mitophagy and the anti-inflammatory effect provoked by 4-OI in vitro.

CONCLUSION

These data suggest that 4-OI ameliorates LPS-induced AKI by suppressing inflammation and oxidative stress and enhancing mitophagy through the overactivation of the Nrf2 signaling pathway, and inactivation of STAT3. Our study identifies 4-OI as a promising pharmacologic for S-AKI.

Aconitate Decarboxylase 1 Deficiency Exacerbates Mouse Colitis Induced by Dextran Sodium Sulfate

Ulcerative colitis is a complex inflammatory bowel disorder disease that can induce rectal and colonic dysfunction. Although the prevalence of IBD in Western countries is almost 0.5% of the general population, genetic causes are still not fully understood. In a recent discovery, itaconate was found to function as an immune-modulating metabolite in mammalian immune cells, wherein it is synthesized as an antimicrobial compound from the citric acid cycle intermediate cis-aconitic acid. However, the association between the Acod1 (Aconitate decarboxylase 1)-itaconate axis and ulcerative colitis has rarely been studied. To elucidate this, we established a DSS-induced colitis model with Acod1-deficient mice and then measured the mouse body weights, colon lengths, histological changes, and cytokines/chemokines in the colon. We first confirmed the upregulation of Acod1 RNA and protein expression levels in DSS-induced colitis. Then, we found that colitis symptoms, including weight loss, the disease activity index, and colon shortening, were worsened by the depletion of Acod1. In addition, the extent of intestinal epithelial barrier breakdown, the extent of immune cell infiltration, and the expression of proinflammatory cytokines and chemokines in Acod1-deficient mice were higher than those in wild-type mice. Finally, we confirmed that 4-octyl itaconate (4-OI) alleviated DSS-induced colitis in Acod1-deficient mice and decreased the expression of inflammatory cytokines and chemokines. To our knowledge, this study is the first to elucidate the role of the Acod1-itaconate axis in colitis. Our data clearly showed that Acod1 deletion resulted in severe DSS-induced colitis and substantial increases in inflammatory cytokine and chemokine levels. Our results suggest that Acod1 may normally play an important regulatory role in the pathogenesis of colitis, demonstrating the potential for novel therapies using 4-OI.

Sulforaphane Reduces SAMHD1 Phosphorylation To Protect Macrophages from HIV-1 Infection

The cellular protein SAMHD1 is important for DNA repair, suppressing LINE elements, controlling deoxynucleoside triphosphate (dNTP) concentrations, maintaining HIV-1 latency, and preventing excessive type I interferon responses. SAMHD1 is also a potent inhibitor of HIV-1 and other significant viral pathogens. Infection restriction is due in part to the deoxynucleoside triphosphatase (dNTPase) activity of SAMHD1 but is also mediated through a dNTPase-independent mechanism that has been described but not explored. The phosphorylation of SAMHD1 at threonine 592 (T592) controls many of its functions. Retroviral restriction, irrespective of dNTPase activity, is linked to unphosphorylated T592. Sulforaphane (SFN), an isothiocyanate, protects macrophages from HIV infection by mobilizing the transcription factor and antioxidant response regulator Nrf2. Here, we show that SFN and other clinically relevant Nrf2 mobilizers reduce SAMHD1 T592 phosphorylation to protect macrophages from HIV-1. We further show that SFN, through Nrf2, triggers the upregulation of the cell cycle control protein p21 in human monocyte-derived macrophages to contribute to SAMHD1 activation. We additionally present data that support another, potentially redox-dependent mechanism employed by SFN to contribute to SAMHD1 activation through reduced phosphorylation. This work establishes the use of exogenous Nrf2 mobilizers as a novel way to study virus restriction by SAMHD1 and highlights the Nrf2 pathway as a potential target for the therapeutic control of SAMHD1 cellular and antiviral functions. IMPORTANCE Here, we show, for the first time, that the treatment of macrophages with Nrf2 mobilizers, known activators of antioxidant responses, increases the fraction of SAMHD1 without a regulatory phosphate at position 592. We demonstrate that this decreases infection of macrophages by HIV-1. Phosphorylated SAMHD1 is important for DNA repair, the suppression of LINE elements, the maintenance of HIV-1 in a latent state, and the prevention of excessive type I interferon responses, while unphosphorylated SAMHD1 blocks HIV infection. SAMHD1 impacts many viruses and is involved in various cancers, so knowledge of how it works and how it is regulated has broad implications for the development of therapeutics. Redox-modulating therapeutics are already in clinical use or under investigation for the treatment of many conditions. Thus, understanding the impact of redox modifiers on controlling SAMHD1 phosphorylation is important for many areas of research in microbiology and beyond.

4-Octyl Itaconate Supplementation Relieves Soybean Diet-Induced Liver Inflammation and Glycolipid Metabolic Disorders by Activating the Nrf2-Pparγ Pathway in Juvenile Gibel Carp

Itaconate is a promising new candidate for anti-inflammatory and metabolic reprogramming, and 4-octyl itaconate (OI) is a cell-permeable itaconate derivative. To investigate the effect of OI in inflammatory response and glycolipid metabolism, we fed gibel carp with a 40% dietary soybean meal diet containing 0.1% OI (SBM + 0.1OI) or not (SBM) and compared these with fishmeal (FM) as reference. Compared with FM, dietary SBM decreased the growth performance, induced inflammation in the intestine and liver, and decreased the glucose utilization ability of the liver. However, 0.1% OI supplementation in SBM significantly increased the growth performance (from 20.11 ± 0.77 to 23.33 ± 0.45 g, P < 0.05), reduced inflammation in different organs through Nrf2 activation, and alleviated SBM-induced high plasma glucose (from 6.06 ± 0.23 to 4.37 ± 0.14 g, P < 0.05) and low crude body lipid (from 4.08 ± 0.17 to 4.91 ± 0.10 g, P < 0.05). Multi-omics revealed that OI had obvious effects on carbohydrate metabolism. OI regulates peroxisome proliferator-activated receptor gamma (ppar-γ), and its target genes (glut2 and gk) enhance liver glycolysis and lipid de novo lipogenesis, which are also dependent on Nrf2 activation. To conclude, dietary 0.1% OI can promote the growth of gibel carp and alleviate foodborne intestinal and hepatic inflammation and abnormal glycolipid metabolism by Nrf2-regulated Pparγ expression.

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.

Mechanisms underlying the therapeutic effects of 4-octyl itaconate in treating sepsis based on network pharmacology and molecular docking

Objective: Through network pharmacology and molecular docking technology, the hub genes, biological functions, and signaling pathways of 4-Octyl itaconate (4-OI) against sepsis were revealed. Methods: Pathological targets of sepsis were screened using GeneCards and GEO databases. Similarly, the pharmacological targets of 4-OI were obtained through Swiss TargetPrediction (STP), Similarity ensemble approach (SEA), and TargetNet databases. Then, all the potential targets of 4-OI anti-sepsis were screened by the online platform Draw Venn diagram, and the hub genes were screened by Cytoscape software. The identified hub genes were analyzed by GO and KEGG enrichment analysis, protein interaction (PPI) network, and molecular and docking technology to verify the reliability of hub gene prediction, further confirming the target and mechanism of 4-OI in the treatment of sepsis. Results: After the target screening of 4-OI and sepsis, 264 pharmacological targets, 1953 pathological targets, and 72 genes related to 4-OI anti-sepsis were obtained, and eight hub genes were screened, namely MMP9, MMP2, SIRT1, PPARA, PTPRC, NOS3, TLR2, and HSP90AA1. The enrichment analysis results indicated that 4-OI might be involved in regulating inflammatory imbalance, immunosuppression, and oxidative stress in developing sepsis. 4-OI protects multiple organ dysfunction in sepsis by acting on hub genes, and MMP9 is a reliable gene for the prognosis and diagnosis of sepsis. The molecular docking results showed that 4-OI binds well to the hub target of sepsis. Conclusion: 4-OI plays an antiseptic role by regulating MMP9, MMP2, SIRT1, PPARA, PTPRC, NOS3, TLR2 and HSP90AA1. These Hub genes may provide new insights into follow-up research on the target of sepsis treatment.

4-octyl itaconate protects against oxidative stress-induced liver injury by activating the Nrf2/Sirt3 pathway through AKT and ERK1/2 phosphorylation

4-octyl itaconate (4-OI) is a cell-permeable itaconate derivative with anti-inflammatory and antioxidant properties. However, its therapeutic potential for oxidative stress-induced liver injury remains unknown. This study investigated the hepatoprotective effects and mechanisms of 4-OI against oxidative damage in in vitro and in vivo models. 4-OI attenuated H2O2-induced cytotoxicity, oxidative stress, and mitochondrial dysfunction in L02 and HepG2 cells. Untargeted metabolomics profiling and pathway analysis identified the PI3K/AKT/mTOR and MAPK pathways as key regulators of 4-OI's protective effects. Specifically, 4-OI induced phosphorylation of AKT and ERK1/2, leading to activation of the Nrf2 signaling pathway. Nrf2 upregulated expression of the mitochondrial deacetylase Sirt3, which subsequently alleviated H2O2-induced cell injury. In mice, 4-OI reduced acetaminophen (APAP)-induced liver injury as evidenced by attenuated hepatocellular necrosis and decreased serum liver enzymes. It also elevated hepatic expression of Nrf2, Sirt3, p-AKT and p-ERK1/2. Inhibition of AKT, ERK1/2 or Nrf2 blocked the protective effects of 4-OI in vitro, suggesting its antioxidant activity is mediated by activating the Nrf2/Sirt3 pathway via AKT and ERK1/2 phosphorylation. In summary, 4-OI exerted antioxidant and hepatoprotective effects by activating the Nrf2/Sirt3 signaling pathway through AKT and ERK1/2 phosphorylation, which were elucidated using in vitro and in vivo oxidative stress models. This provides novel insights into the mechanisms of 4-OI against oxidative stress-related liver diseases.

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.

Pharmacological inhibition of STING-mediated GPX4 autophagic degradation by 4-octyl itaconate ameliorates sepsis-induced acute kidney injury

The precise pathogenic mechanisms underlying sepsis-induced acute kidney injury (AKI) remain elusive. Emerging evidence suggests a link between tubular ferroptosis and the pathogenesis of AKI, though the regulatory pathways are not fully understood. Stimulator of interferon genes (STING), previously recognized as a pivotal mediator of innate immunity via DNA-sensing pathways, is increasingly associated with lipid peroxidation, a hallmark of ferroptosis, and 4-octyl itaconate (4-OI) has been shown to inhibit STING activation, exerting anti-inflammatory effects. This study investigates the protective mechanisms of 4-OI in sepsis-AKI. Following cecal ligation and puncture (CLP), inflammation, oxidative stress, and ferroptosis levels in kidney tissue increased. Both 4-OI and ferrostatin-1 (Fer-1) mitigated renal ferroptosis, exerting anti-inflammatory and antioxidant stress effects, and improved renal function. Consistently, in vitro experiments demonstrated that 4-OI reduced ferroptosis in human renal proximal tubule (HK-2) cells induced by lipopolysaccharide (LPS). Mechanistically, 4-OI suppressed LPS-induced activation of the STING pathway and reduced levels of inflammatory cytokines in a manner independent of NF-E2-related factor 2 (Nrf2). Additionally, 4-OI inhibited STING transcription through the activation of Nrf2. These dual actions effectively suppressed LPS-induced STING pathway activation, thereby inhibiting STING-mediated autophagic degradation of glutathione peroxidase 4 (GPX4), reducing reactive oxygen species (ROS) accumulation, and alleviating ferroptosis. In summary, 4-OI is a promising therapeutic candidate, functioning both as a STING inhibitor and a ferroptosis inhibitor, with potential applications in the treatment of sepsis.

4-Octyl itaconate promotes alveolar ridge preservation following tooth extraction

The search for medications that can effectively reduce alveolar bone loss following tooth extraction is of great interest. This study aimed to observe the roles of 4-octyl itaconate (4-OI) in RANKL-induced osteoclastogenesis of bone marrow macrophages (BMMs) in vitro. Mandibular second molars were extracted to evaluate whether 4-OI could alleviate alveolar bone loss. 4-OI inhibited RANKL-induced osteoclastogenesis and promoted Nrf2 expression in bone marrow macrophages in vitro. Positive Nrf2 expressions were observed in inflammatory cells and osteoclasts in vivo. Treatment with 4-octyl itaconate increased Nrf2 expression, resulting in reduced inflammatory infiltration and osteoclastic activity after tooth extraction. Furthermore, increased expression of OCN and enhanced-alveolar bone healing of extraction socket were observed in the 4-OI group compared to the control group. Our results suggested that 4-OI could serve as a promising pharmacologic candidate for alveolar ridge preservation by alleviating alveolar bone loss following tooth extraction in rats.

4-Octyl itaconate attenuates renal tubular injury in db/db mice by activating Nrf2 and promoting PGC-1α-mediated mitochondrial biogenesis

Objectives: The aim of this study was to investigate the mechanism of itaconate's potential effect in diabetic kidney disease.

Methods: Renal immune responsive gene 1 (IRG1) levels were measured in db/db mice and streptozotocin (STZ) + high-fat diet (HFD)-induced diabetic mice. Irg1 knockout mice were generated. db/db mice were treated with 4-octyl itaconate (4-OI, 50 mg/kg), a derivative of itaconate, for 4 weeks. Renal function and morphological changes were investigated. Ultrastructural alterations were determined by transmission electron microscopy.

Results: Renal IRG1 levels were reduced in two diabetic models. STZ+HFD-treated Irg1 knockout mice exhibited aggravated renal tubular injury and worsened renal function. Treatment with 4-OI lowered urinary albumin-to-creatinine ratio and blood urea nitrogen levels, and restored renal histological changes in db/db mice. It improved mitochondrial damage, increased expressions of peroxisome-proliferator-activated receptor γ coactivator-1α (PGC-1α) and mitochondrial transcription factor A (TFAM) in the renal cortex of db/db mice. These were confirmed in vitro; 4-OI improved high glucose-induced abnormal mitochondrial morphology and TFAM expression in HK-2 cells, effects that were inhibited by PGC-1α silencing. Moreover, 4-OI reduced the number of apoptotic cells in the renal cortex of db/db mice. Further study showed that 4-OI increased renal Nrf2 expression and decreased oxidative stress levels in db/db mice. In HK-2 cells, 4-OI decreased high glucose-induced mitochondrial ROS production, which was reversed by Nrf2 silencing. Nrf2 depletion also inhibited 4-OI-mediated regulation of PGC-1α, TFAM, and mitochondrial apoptotic protein expressions.

Conclusions: 4-OI attenuates renal tubular injury in db/db mice by activating Nrf2 and promoting PGC-1α-mediated mitochondrial biogenesis.

Activation of Nrf2 pathway by 4-Octyl itaconate enhances donor lung function in cold preservation settings

BACKGROUND

Lung transplantation is the primary treatment for end-stage lung diseases. However, ischemia-reperfusion injury (IRI) significantly impacts transplant outcomes. 4-Octyl itaconate (4-OI) has shown potential in mitigating organ IRI, although its effects in lung transplantation require further exploration.

METHODS

BEAS-2B cells were used to model transplantation, assessing the effects of 4-OI through viability, apoptosis, and ROS assays. qRT-PCR analyzed cytokine transcription post-cold ischemia/reperfusion (CI/R). RNA sequencing and Gene Ontology analysis elucidated 4-OI's mechanisms of action, confirmed by Western blotting. ALI-airway and lung transplantation organoid models evaluated improvements in bronchial epithelial morphology and function due to 4-OI. ELISA measured IL-6 and IL-8 levels. Rat models of extended cold preservation and non-heart-beating transplantation assessed 4-OI's impact on lung function, injury, and inflammation.

RESULTS

Our findings indicate that 4-OI (100 µM) during cold preservation effectively maintained cell viability, decreased apoptosis, and reduced ROS production in BEAS-2B cells under CI/R conditions. It also downregulated pro-inflammatory cytokine transcription, including IL1B, IL6, and TNF. Inhibition of Nrf2 partially reversed these protective effects. In cold preservation solutions, 4-OI upregulated Nrf2 target genes such as NQO1, HMOX1, and SLC7A11. In ALI airway models, 4-OI enhanced bronchial epithelial barrier integrity and ciliary beat function after CI/R. In rat models, 4-OI administration improved lung function and reduced pulmonary edema, tissue injury, apoptosis, and systemic inflammation following extended cold preservation or non-heart-beating lung transplantation.

CONCLUSIONS

Incorporating 4-OI into cold preservation solutions appears promising for alleviating CI/R-induced bronchial epithelial injury and enhancing lung transplant outcomes via Nrf2 pathway activation.

4-Octyl Itaconate Attenuates Postmenopausal Osteoporosis by Inhibiting Ferroptosis and Enhancing Osteogenesis via the Nrf2 Pathway

Bone marrow mesenchymal stem cells (BMSCs) play an important role in bone metabolism and tissue repair, and their ability to differentiate into osteoblasts is crucial in the treatment of bone diseases such as postmenopausal osteoporosis (PMOP). However, the function of BMSCs may be affected by ferroptosis. Ferroptosis is a cell death mode characterized by excess Fe2+ and lipid peroxidation, which significantly affects the survival rate and differentiation ability of BMSCs. This study investigated the effect of exogenous itaconate derivative 4-octyl itaconate (4-OI) on Erastin-induced BMSCs ferroptosis. The results showed that 4-OI significantly inhibited Erastin-induced BMSCs ferroptosis by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway, reduced reactive oxygen species levels and oxidative damage, and restored antioxidant capacity. At the same time, 4-OI promoted the osteogenic differentiation of BMSCs. Further experiments showed that Nrf2-IN-1, an inhibitor of the Nrf2 pathway, could reverse the protective effect of 4-OI. In vivo, 4-OI was shown to reduce bone loss in ovariectomized (OVX) mice, as assessed by Micro-CT analysis. Immunofluorescence staining further revealed increased GPX4 and Nrf2 expression in vertebral tissues following 4-OI treatment. These results indicate that 4-OI improves ferroptosis of BMSCs and enhances osteogenic differentiation ability by activating the Nrf2 pathway, providing new research ideas and potential targets for the treatment of PMOP.

4-octyl Itaconate Attenuates Acute Pancreatitis and Associated Lung Injury by Suppressing Ferroptosis in Mice

Acute pancreatitis (AP) is a common gastrointestinal emergency requiring hospitalization. In recent years, several studies have demonstrated a role for 4-octyl itaconate (4-OI) in anti-inflammatory and oxidative stress injury. However, the potential effects of 4-OI in AP have not been investigated. Caerulein and LPS were used to induce experimental AP models in mice and AR42J cells and then studied by histopathology, biochemical, and molecular analysis. Ferroptosis inhibitor ferrostatin-1 effectively improves pancreatic injury and reduces lipid peroxidation products in experimental AP mice. 4-OI treatment significantly alleviated pancreatic and AP-associated lung injury and inflammation in experimental AP mice by inhibiting ferroptosis. The ferroptosis activator Erastin blocked the protective effect of 4-OI against pancreatic injury in AP, validating that 4-OI alleviates pancreatitis injury through ferroptosis. In vitro experiments further confirmed that 4-OI treatment ameliorated AP-induced pancreatic injury by inhibiting ferroptosis. Our study, for the first time, found that 4-OI ameliorates AP and AP-related lung injury by inhibiting ferroptosis in experimental AP mice, providing a new therapeutic target for alleviating AP.

Fabrication of injectable alginate hydrogels with sustained release of 4-octyl itaconate for articular anti-inflammatory

BACKGROUND

Osteoarthritis (OA) is a chronic and degenerative joint disease that remains a great challenge in treatment due to the lack of effective therapies. 4-octyl itaconate (4-OI) is a novel and potent modulator of inflammation for the treatment of inflammatory disease. However, the clinical usage of 4-OI is limited due to its poor solubility and low bioavailability. As a promising drug delivery strategy, injectable hydrogels offers an effective approach to address these limitations of 4-OI.

OBJECTIVE

The aim of the study was to verify that the composite 4-OI/SA hydrogels could achieve a controlled release of 4-OI and reduce damage to articular cartilage in the group of osteoarthritic rats treated with the system.

METHODS

In this study, an injectable composite hydrogel containing sodium alginate (SA) and 4-octyl itaconate (4-OI) has been developed for continuous intra-articular administration in the treatment of OA.

RESULTS

After intra-articular injection in arthritic rats, the as-prepared 4-OI/SA hydrogel containing of 62.5 μM 4-OI effectively significantly reduced the expression of TNF-α, IL-1β, IL-6 and MMP3 in the ankle fluid. Most importantly, the as-prepared 4-OI/SA hydrogel system restored the morphological parameters of the ankle joints close to normal.

CONCLUSION

4-OI/SA hydrogel shows a good anti-inflammatory activity and reverse cartilage disruption, which provide a new strategy for the clinical treatment of OA.

Itaconate alleviates anesthesia/surgery-induced cognitive impairment by activating a Nrf2-dependent anti-neuroinflammation and neurogenesis via gut-brain axis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common neurological complication of anesthesia and surgery in aging individuals. Neuroinflammation has been identified as a hallmark of POCD. However, safe and effective treatments of POCD are still lacking. Itaconate is an immunoregulatory metabolite derived from the tricarboxylic acid cycle that exerts anti-inflammatory effects by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. In this study, we investigated the effects and underlying mechanism of 4-octyl itaconate (OI), a cell-permeable itaconate derivative, on POCD in aged mice.

METHODS

A POCD animal model was established by performing aseptic laparotomy in 18-month-old male C57BL/6 mice under isoflurane anesthesia while maintaining spontaneous ventilation. OI was intraperitoneally injected into the mice after surgery. Primary microglia and neurons were isolated and treated to lipopolysaccharide (LPS), isoflurane, and OI. Cognitive function, neuroinflammatory responses, as well as levels of gut microbiota and their metabolites were evaluated. To determine the mechanisms underlying the therapeutic effects of OI in POCD, ML385, an antagonist of Nrf2, was administered intraperitoneally. Cognitive function, neuroinflammatory responses, endogenous neurogenesis, neuronal apoptosis, and Nrf2/extracellular signal-related kinases (ERK) signaling pathway were evaluated.

RESULTS

Our findings revealed that OI treatment significantly alleviated anesthesia/surgery-induced cognitive impairment, concomitant with reduced levels of the neuroinflammatory cytokines IL-1β and IL-6, as well as suppressed activation of microglia and astrocytes in the hippocampus. Similarly, OI treatment inhibited the expression of IL-1β and IL-6 in LPS and isoflurane-induced primary microglia in vitro. Intraperitoneal administration of OI led to alterations in the gut microbiota and promoted the production of microbiota-derived metabolites associated with neurogenesis. We further confirmed that OI promoted endogenous neurogenesis and inhibited neuronal apoptosis in the hippocampal dentate gyrus of aged mice. Mechanistically, we observed a decrease in Nrf2 expression in hippocampal neurons both in vitro and in vivo, which was reversed by OI treatment. We found that Nrf2 was required for OI treatment to inhibit neuroinflammation in POCD. The enhanced POCD recovery and promotion of neurogenesis triggered by OI exposure were, at least partially, mediated by the activation of the Nrf2/ERK signaling pathway.

CONCLUSIONS

Our findings demonstrate that OI can attenuate anesthesia/surgery-induced cognitive impairment by stabilizing the gut microbiota and activating Nrf2 signaling to restrict neuroinflammation and promote neurogenesis. Boosting endogenous itaconate or supplementation with exogenous itaconate derivatives may represent novel strategies for the treatment of POCD.

4-octyl itaconate alleviates cisplatin-induced ferroptosis possibly via activating the NRF2/HO-1 signalling pathway

Ferroptosis, characterized by iron-dependent lipid reactive oxygen species (ROS) accumulation, plays a pivotal role in cisplatin-induced ototoxicity. Existing research has suggested that in cisplatin-mediated damage to auditory cells and hearing loss, ferroptosis is partially implicated. 4-Octyl itaconate (4-OI), derived from itaconic acid, effectively permeates cell membranes, showcasing potent anti-inflammatory as well as antioxidant effects in several disease models. Our study aimed to investigate the effect of 4-OI on cisplatin-induced ferroptosis and the underlying molecular mechanisms. The survival rates of HEI-OC1 cells and mice cochlea hair cells were measured by CCK8 and immunofluorescence, respectively. The auditory brainstem response (ABR) audiometry was used to detect changes in hearing thresholds in mice before and after treatment. Levels of ROS were evaluated by DCFH-DA. Real-time PCR quantified inflammatory cytokines TNF-α, IL-6 and IL-1β. Network Pharmacology and RNA sequencing (RNA-seq) analysis of the potential mechanism of 4-OI resistance to cisplatin-induced ferroptosis. The expressions of ferroptosis-related factors (GPX4, SLC7A11 and PTGS2) and important antioxidant factors (NRF2, HO-1, GCLC and NQO1) were tested by real-time PCR, Western blot and immunofluorescence. Results demonstrated cisplatin-induced significant ROS and inflammatory factor release, reduced NRF2 expression, hindered nuclear translocation and activated ferroptosis. Pretreatment with 4-OI exhibited anti-inflammatory and antioxidant effects, along with resistance to ferroptosis, ultimately mitigating cisplatin-induced cell loss. In the present study, we show that 4-OI inhibits cisplatin-induced ferroptosis possibly through activation of the NRF2/HO-1 signalling pathway, thereby exerting a protective effect against cisplatin-induced damage to auditory cells, and providing a new therapeutic strategy for cisplatin-induced hearing loss.

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 improves the viability of D66H cells by regulating the KEAP1-NRF2-GCLC/HO-1 pathway

As a novel nuclear factor E2-related factor 2 (NRF2) activator, the itaconate has shown significant therapeutic potential for oxidative stress diseases. However, its role in Vohwinkel syndrome in relation to the gap junction protein beta 2 (GJB2) mutation is still unclear. This study aimed at investigating the effect of 4-octyl itaconate (OI) on HaCaT and D66H cells and clarify its potential mechanism in vitro. The optimal concentration and treatment time of OI on HaCaT cells and D66H cells were determined by CCK-8 and LDH experiments. The effect of OI on cell proliferation was detected by EdU staining and FACS analysis of PI, while the apoptosis was evaluated by TUNEL staining and FACS analysis of Annexin V. The ROS staining was performed, and the levels of SOD, MDA, GSH and GSH/GSSG were detected to evaluate the effect of OI on oxidative damage induced by D66H-type mutation. CO-IP, Western blot, immunofluorescence and qPCR analyses were employed to detect the activation of KEAP1-NRF2-GCLC/HO-1 pathway by OI. Finally, sh-NRF2 was used to confirm the activation of this pathway by OI. Results showed that OI could improve the cell viability decreased by GJB2 gene mutation by regulating the balance between cell growth and apoptosis induced by oxidative damage. Furthermore, this alleviation process was regulated by the KEAP1-NRF2-HO-1/GCLC pathway. In conclusion, OI could improve the viability of HaCaT and D66H cells via regulating the KEAP1-NRF2-GCLC/HO-1 pathway, which provided a wide spectrum of potential targets for effective therapeutic treatments of Vohwinkel syndrome in the clinic.

Injectable Hydrogel of Chitosan-Octyl Itaconate Conjugate Modulates Inflammatory Response

Itaconic acid and its derivative 4-octyl itaconate (OI) represent a novel anti-inflammatory medication that has demonstrated efficacy in multiple inflammation models because of its minimal side effects. Recently, natural polymers conjugated with small molecule drugs, known as polymer-drug conjugates (PDCs), have emerged as a promising approach to sustained drug release. In this work, we reported an approach to prepare a PDC containing an OI and make it into an injectable hydrogel. Chitosan (CS) was selected for PDC synthesis because of its abundant free amino groups that can be conjugated with molecules containing carboxyl groups by carbodiimide chemistry. We used an ethanol/water cosolvent system to synthesize a CS-OI conjugate via EDC/NHS catalysis. The CS-OI conjugate had improved water solubility and unique anti-inflammatory activity and did not show compromised antibacterial activity compared with unmodified CS. Beta-glycerophosphate (β-GP) cross-linked CS-OI hydrogel exhibited good injectability with sustainable OI release and effectively modulated inflammatory response in a rat model. Therefore, this study provides valuable insights into the design of PDC hydrogels with inflammatory modulatory properties.