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Increased injury on intestines in Nrf2-/-mice after 30% TBSA burn injury. A. Histopathological analysis of intestines by H&E staining 24 hours after burn injury. Magnification, ×10. Scale bars represent 200 μm. b. Changes of villus height after burn injury. Villus height was measured in 5 random fields in each slice. 3 mice were counted in each group. Data are expressed as mean ± SEM. c. Apoptotic cells in sections of intestinal tissues were detected by TUNEL assay according to the manufacturer's instructions (green staining). Confocal laser scanning microscopy analyzed samples. Magnification, ×20. Scale bars represent 100 μm. D. Quantitative analysis of apoptotic cells. 5 random fields were counted in each slice. 3 mice were counted in each group. Data are expressed as mean ± SEM. E. Intestinal permeability was assessed 4h after burn by measuring the systemic plasma concentration of intraluminally injected 4.4-kd FITCdextran . Data are expressed as mean ± SEM. *p < 0.05 vs Sham, †p < 0.05 vs Nrf2+/+.
Source publication
Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is a basic leucine zipper transcription factor that principally defends against oxidative stress and also plays a unique role in severe sepsis. However, its contribution to intestinal injury and death after burn trauma is unclear.In this study, wild-type (Nrf2+/+) and Nrf2-deficient (Nrf2-/-) mice...
Contexts in source publication
Context 1
... of proximal ileum from each experimental group were assessed for evidence of histologic injury 24 h after burn injury. The histologic appearance of the intestines of the burned animals demonstrated marked blunting and shortening of the villi, especially in the Nrf2 −/− mice ( Figure 3A). The villi were also significantly shorter in the Nrf2 −/− mice than in the Nrf2 +/+ mice (157 ± 9.08 µm vs. 279 ± 6.21 µm; p < 0.0001; Figure 3B). ...
Context 2
... histologic appearance of the intestines of the burned animals demonstrated marked blunting and shortening of the villi, especially in the Nrf2 −/− mice ( Figure 3A). The villi were also significantly shorter in the Nrf2 −/− mice than in the Nrf2 +/+ mice (157 ± 9.08 µm vs. 279 ± 6.21 µm; p < 0.0001; Figure 3B). Burn injury also led to an increase in the number of TUNEL-positive cells in both Nrf2 +/+ and Nrf2 −/− mice, but this increase was three times greater in the Nrf2 −/− mice than in the Nrf2 +/+ mice ( Figure 3C, 3D). ...
Context 3
... villi were also significantly shorter in the Nrf2 −/− mice than in the Nrf2 +/+ mice (157 ± 9.08 µm vs. 279 ± 6.21 µm; p < 0.0001; Figure 3B). Burn injury also led to an increase in the number of TUNEL-positive cells in both Nrf2 +/+ and Nrf2 −/− mice, but this increase was three times greater in the Nrf2 −/− mice than in the Nrf2 +/+ mice ( Figure 3C, 3D). Intestinal permeability is a good indicator of the gut barrier function, which is often compromised after major thermal injury [23]. ...
Context 4
... has been reported that intestinal permeability can increase for up to 5 h after burn injury [24]. Consistent with this finding, in our study, both Nrf2 +/+ and Nrf2 −/− mice showed increased intestinal permeability 4 h after burn injury, but the increase was four times greater in the Nrf2 −/− mice than in the Nrf2 +/+ mice ( Figure 3E). ...
Citations
... Considering that insulin possesses anti-inflammatory properties, the increased Nrf-2 expression in the ICNP-treated group indicated that ICNP regulates inflammation through Nrf-2 activation. Few studies show the protective roles of Nrf-2 in burn trauma-induced intestinal injury and burn-induced cardiac dysfunction [68,69] as well as the role of topical insulin [33] or insulin nanoparticles [36] in burn wound healing, but none has implicated the role of insulin in activation of Nrf-2 pathway. Further, different formulations are being developed for burn wound healing, including the topical application of simvastatin on the burn wound Wistar rat model, and it was found to promote healing by modulating Akt/mTOR signaling pathway along with increased CD31 VEGF levels. ...
Burn injuries are characterized by prolonged inflammatory phases, neurovascular damage, and hypermetabolism, eventually causing improper tissue regeneration. Insulin has gained considerable attention in normal and diabetic wound healing, yet its role in burn wounds remains poorly understood. In this study, insulin-chitosan nano-formulations (ICNP) were synthesized using a simple and robust mechanism and characterized to monitor specific interactions between insulin and chitosan, and the particles measuring approximately 30 nm in size exhibited mild alterations in the amide I, II, and III bonds of the insulin protein along with impressive insulin loading efficiency of 88.725 ± 0.295% under physiological conditions, and significantly improved burn wound healing in vitro (HEKa cells) and in vivo (murine third-degree burn model). The underlying mechanism behind superior wound closure and tissue remodeling was attributed to significant early phase reduction of pro-inflammatory cytokine IL-6 levels in ICNP-treated mice, while anti-inflammatory cytokine IL-10 levels became markedly elevated, resulting in enhanced re-epithelialization and collagen deposition. Furthermore, treatment of ICNP was associated with unregulated expression of Nrf-2, a key regulator of oxidative stress and inflammation, indicating their molecular crosstalk. These findings highlight the potential of ICNP as a promising therapeutic formulation for burn wound healing, promoting wound closure by modulating inflammatory phases, making it a valuable candidate for further clinical development in burn care.
Graphical Abstract
... The Nrf2-Keap1 pathway plays a key role in resisting intestinal mucosal injury as it was observed that in epithelial cells the nuclear translocation of Nrf2 significantly suppressed ROS generation and enhanced cell survival (Rodríguez-Ramiro et al., 2012). The protective effect of Nrf2 in maintaining the barrier has been proved in various experimental models, including Salmonella Typhimurium infection in mice (Theiss et al., 2009), and burn and brain induced intestinal barrier damage (Chen et al., 2016;Liu et al., 2017) or severe sepsis (Yu et al., 2017). Chickens fed with AGPs had shown to increase the expression of Nrf2 . ...
It has been hypothesized that reducing the bioenergetic costs of gut inflammation as an explanation for the effect of antibiotic growth promoters (AGPs) on animal efficiency, framing some observations but not explaining the increase in growth rate or the prevention of infectious diseases. The host's ability to adapt to alterations in environmental conditions and to maintain health involves managing all physiological interactions that regulate homeostasis. Thus, metabolic pathways are vital in regulating physiological health as the energetic demands of the host guides most biological functions. Mitochondria are not only the metabolic heart of the cell because of their role in energy metabolism and oxidative phosphorylation, but also a central hub of signal transduction pathways that receive messages about the health and nutritional states of cells and tissues. In response, mitochondria direct cellular and tissue physiological alterations throughout the host. The endosymbiotic theory suggests that mitochondria evolved from prokaryotes, emphasizing the idea that these organelles can be affected by some antibiotics. Indeed, therapeutic levels of several antibiotics can be toxic to mitochondria, but subtherapeutic levels may improve mitochondrial function and defense mechanisms by inducing an adaptive response of the cell, resulting in mitokine production which coordinates an array of adaptive responses of the host to the stressor(s). This adaptive stress response is also observed in several bacteria species, suggesting that this protective mechanism has been preserved during evolution. Concordantly, gut microbiome modulation by subinhibitory concentration of AGPs could be the result of direct stimulation rather than inhibition of determined microbial species. In eukaryotes, these adaptive responses of the mitochondria to internal and external environmental conditions, can promote growth rate of the organism as an evolutionary strategy to overcome potential negative conditions. We hypothesize that direct and indirect subtherapeutic AGP regulation of mitochondria functional output can regulate homeostatic control mechanisms in a manner similar to those involved with disease tolerance.
... Considering that insulin possesses anti-in ammatory properties, the increased Nrf-2 expression in the ICNP treated group indicated that this nano-formulation may regulate in ammation through Nrf-2 activation. There are very few reports that indicate protective roles of Nrf-2 in burn trauma induced intestinal injury and burn induced cardiac dysfunction [54,55] as well as role of topical insulin [34] or insulin nanoparticles [37] in burn wound healing, bur no studies has implicated role of insulin in activation of Nrf-2 pathway. Our study on burn wound mitigation with Chitosan insulin nano-formulation,ICNP, showed effective modulation of in ammatory phases by activation of Nrf-2 pathway underscoring its promise as a therapeutic intervention in burn care and managements. ...
Burn injuries are characterized by prolonged inflammatory phases, neurovascular damage, and hypermetabolism, eventually causing improper tissue regeneration. Insulin has gained considerable attention in normal and diabetic wound healing, yet its role in burn wounds remains poorly understood. In this study, insulin-chitosan nano-formulations (ICNP) were synthesized using a simple and robust mechanism and characterized to monitor specific interactions between insulin and chitosan, and the particles measuring approximately 30 nm in size exhibited mild alterations in the amide I, II, and III bonds of the insulin protein along with impressive insulin loading efficiency of 88.725 ± 0.295% under physiological conditions, and significantly improved burn wound healing in vitro (HEKa cells) and in vivo (murine third-degree burn model). The underlying mechanism behind superior wound closure and tissue remodeling was attributed to significant early phase reduction of pro-inflammatory cytokine IL-6 levels in ICNP-treated mice, while anti-inflammatory cytokine IL-10 levels became markedly elevated, resulting in enhanced re-epithelialization and collagen deposition. Furthermore, treatment of ICNP was associated with unregulated expression of Nrf-2, a key regulator of oxidative stress and inflammation, indicating their molecular crosstalk. These findings highlight the potential of ICNP as a promising therapeutic formulation for burn wound healing, promoting wound closure by modulating inflammatory phases, making it a valuable candidate for further clinical development in burn care.
... These results may be related to cellular response against burn-associated oxidative stress. A study performed by Chen and colleagues demonstrated that mice that lack Nrf-2 were more vulnerable to burn trauma-associated intestinal injury and systemic inflammation and had a markedly high lethality rate [30]. Furthermore, downregulated mRNA expressions of Nrf-2, NQO-1, and HO-1 together with upregulated mRNA expression of Keap-1 was observed in the wound tissue of diabetic rats [26]. ...
... In humans, polymorphisms of Nrf2 correlate with greater risk for developing ALI after major trauma (16). In addition, earlier studies using mouse injury models (17,18), including burn (17), have described NRF2 controlling gastrointestinal permeability and systemic proinflammatory cytokine levels. An agonist of the NRF2 pathway is bardoxolone methyl (CDDO-Me) (19), which binds to specific cysteine residues on Keap1 and drives NRF2 protein translocation and accumulation in the nucleus. ...
... In humans, polymorphisms of Nrf2 correlate with greater risk for developing ALI after major trauma (16). In addition, earlier studies using mouse injury models (17,18), including burn (17), have described NRF2 controlling gastrointestinal permeability and systemic proinflammatory cytokine levels. An agonist of the NRF2 pathway is bardoxolone methyl (CDDO-Me) (19), which binds to specific cysteine residues on Keap1 and drives NRF2 protein translocation and accumulation in the nucleus. ...
... As discussed earlier, NRF2 is a transcription factor that maintains tissue homeostasis after cellular stress. Earlier studies have described NRF2 controlling gastrointestinal permeability and systemic proinflammatory cytokine levels (17). Previous studies have not been translational, with other groups using mouse models that were free from vascular stress, clinically relevant volumes of fluid resuscitation, and inhalation injury. ...
Major burn injury is associated with systemic hyper-inflammatory and oxidative stresses that encompass the wound, vascular, and pulmonary systems that contribute to complications and poor outcomes. These stresses are exacerbated if there is a combined burn and inhalation injury (B + I), which leads to increases in morbidity and mortality. Nuclear Factor-Erythroid-2-Related Factor (NRF2) is a transcription factor that functions to maintain homeostasis during stress, in part by modulating inflammation and oxidative injury. We hypothesized that the NRF2-mediated homeostasis following burn alone and combined B + I injury is insufficient, but that pharmacological activation of the NRF2 pathway has the potential to reduce/reverse acute hyper inflammatory responses. We found that after burn and B + I injury, Nrf2-/- mice have higher mortality and exhibit greater pulmonary edema, vascular permeability, and exacerbated pulmonary and systemic pro-inflammatory responses compared to injured wildtype controls. Transcriptome analysis of lung tissue revealed specific Nrf2-dependent dysregulated immune pathways after injury. In wildtype mice, we observed that B + I injury induces cytosolic, but not nuclear, accumulation of NRF2 protein in the lung microenvironment compared to sham injured controls. Bardoxolone methyl (CDDO-Me)-containing microparticles (CDDO-MP) were developed that allow for dilution in saline and stable release of CDDO-Me. When delivered i/p into mice 1 hour after B + I injury, CDDO-MP significantly reduced mortality and cytokine dysfunction compared to untreated B + I animals. These data implicate the role of NRF2 regulation of pulmonary and systemic immune dysfunction following burn and B + I injury, yet also a deficiency in controlling immune dysregulation. Selectively activating the NRF2 pathway may improve clinical outcomes in burn and B + I patients.
... These data support many other studies which have shown that activating the keap-1/Nrf2 axis is an effective therapy to alleviate intestinal inflammatory disorders (Chen, Zhang, Ma, Ni, & Zhao, 2016;Li et al., 2018;Sabzevary-Ghahfarokhi et al., 2018;Wen et al., 2019). In addition, they support many previous studies that have examined ISL's therapeutic potential. ...
This study examined if isoliquiritigenin (ISL) attenuates high-fat diet (HFD)-induced intestinal damage and if this involves modulating Nrf2. Rats included 5 groups (n = 8/group): control (vehicle), ISL, HFD, HFD + ISL, and HFD + ISL + brusatol (an inhibitor of Nrf2). Treatments with the vehicle and ISL (30 mg/kg) were given orally. With no effect on intestinal lipids, ISL improved the duodenal structure in HFD rats and reduced the duodenal levels of malondialdehyde, tumor necrosis factor-α, interleukin-6, macrophage chemoattractant protein-1, and nuclear levels of NF-κB p65. Also, ISL increased the intestinal levels of superoxide dismutase, catalase, glutathione, and the cytoplasmic and nuclear levels of Nrf2. Furthermore, ISL lowered circulatory levels of lipopolysaccharides, deactivated the myosin light chain kinase (MLCK), and increased mRNA claudin-1, occluding, and zonula occludens‑1. All these effects were prevented by co-treatment of brusatol. In conclusion, ISL is a potent activator of Nrf2 intestinal inflammatory disorders.
... 15 Although no reports have been made about NFE2L2 in myocytes after burn, NFE2L2-deficient transgenic mice were found to be more susceptible to burninduced intestinal injury. 18 Both SIRT1 and PGC1a activate NFE2L2, linking the NFE2L2-ARE and AMPK-SIRT1-PGC1a pathways. 19,20 Available data indicate that burn-induced myocardial dysfunction might be related to mitochondrial oxidative stress. ...
... 38 It was demonstrated that mice lacking NFE2L2 were more susceptible to burn-induced intestinal injury, had more systemic inflammation, and a lower survival rates. 18 Our study demonstrated that NFE2L2 mRNA level as well as NFE2L2regulated genes, including HO1, NADH quinone oxidoreductase 1, glutamatecysteine ligase catalytic subunit, manganese superoxide dismutase, and GpX1 were significantly decreased after burn. ...
Background
Imbalance of oxidants/antioxidants results in heart failure, contributing to mortality after burn injury. Cardiac mitochondria are a prime source of ROS, and a mitochondrial-specific antioxidant may improve burn-induced cardiomyopathy. We hypothesize that the mitochondrial-specific antioxidant, Mito-TEMPO, could protect cardiac function after burn.
Study design
Male rats had a 60% TBSA scald burn injury and were treated with/without Mito-TEMPO (7 mg·kg-1, ip) and harvested at 24 hours post burn. Echocardiography (ECHO) was employed for measurement of heart function. Masson Trichrome and H & E staining were used for cardiac fibrosis and immune response. O2K system assessed mitochondria function in vivo. qPCR was used for mitochondrial DNA replication and gene expression.
Results
Burn-induced cardiac dysfunction, fibrosis, and mitochondrial damage were assessed by measurement of mitochondrial function, DNA replication, and DNA-encoded ETC-related gene expression. Mito-TEMPO partially improved the abnormal parameters. Burn-induced cardiac dysfunction was associated with crosstalk between the NFE2L2-ARE pathway, PDE5A-PKG pathway, PARP1-POLG-mtDNA replication pathway, and mitochondrial SIRT signaling.
Conclusions
Mitochondrial-specific antioxidant (Mito-TEMPO) reversed burn-induced cardiac dysfunction by rescuing cardiac mitochondrial dysfunction. Mitochondria-targeted antioxidants may be an effective therapy for burn-induced cardiac dysfunction.
... Increasing evidences have demonstrated that Nrf2 played an important role in protecting the intestinal barrier, and Nrf2 dysfunction would lead to intestinal barrier disruption (Jin et al., 2009;Singh et al., 2019;Wen et al., 2019). Previous studies supported the viewpoint that Nrf2 deficiency impaired intestinal barrier function through disrupting energy-dependent tight junction (Chen et al., 2016;Jin et al., 2008), and oral administration of the Nrf2 activator dh404 was observed to decrease the colon inflammation and restore epithelial tight junction protein levels in chronic kidney disease rats (Lau et al., 2015). Therefore, Nrf2 may play an important role in B. cereus and B. subtilis supplementation improving intestinal barrier of grass carp in this study. ...
This study was aimed to evaluate the effects of dietary supplementation of probiotics Bacillus cereus (BC), B. subtilis (BS), Paracoccus marcusii (PM), and Lactobacillus plantarum (LP) on growth, immune response, antioxidant property, and intestine health of juvenile grass carp. Our results showed that dietary probiotics could promote the growth performance, which was significantly increased in BS, PM, and LP groups compared to the fish in Control group. Also, probiotics supplementation significantly enhanced the immunity of fish measured by the content of C3 and C4, and/or AKP activity in serum, and elevated antioxidant property of intestine accompanying by a significantly lower content of malondialdehyde. Compared to Control group, dietary B. cereus and B. subtilis significantly affected intestinal antioxidant system through Nrf2 signaling pathway by up-regulating the expression of catalase, CuZn superoxide dismutase and/or Mn superoxide dismutase, and further improved the intestinal barrier function by up-regulating mRNA levels of ZO-1, ZO-2, ZO-3, and Clauding-12. Besides, B. cereus, P. marcusii, and L. plantarum supplementation could decrease intestinal inflammation by suppressing TLR4 signaling pathway, meanwhile P. marcusii supplementation up-regulated the expression of ZO-2 and ZO-3. Overall, our results indicated that dietary B. cereus, B. subtilis, P. marcusii, and L. plantarum had a positive impact on the growth performance, immunity and antioxidant property of grass carp, and B. cereus, B. subtilis, and P. marcusii exerted benefits on the intestinal health through elevating antioxidant property and decreasing permeability of intestine.
... While no reports have been made regarding NFE2L2 in myocytes after burn, NFE2L2 deficient transgenic mice were found to be more susceptible to burn-induced intestinal injury (18). Both SIRT1 and PGC1α activate NFE2L2, linking the NFE2L2-ARE and AMPK-SIRT1-PGC1α pathways (19,20) Available data indicates that burn-induced myocardial dysfunction may be related to mitochondrial oxidative stress. ...
... In this role, NFE2L2 activity has been shown to be an important disease modifier in many oxidative/inflammatory diseases, such as asthma, sepsis, and pulmonary fibrosis, in which decreased NFE2L2 activity exacerbates disease progression (38). It was demonstrated that mice lacking NFE2L2 were more susceptible to burn-induced intestinal injury, had more systemic inflammation, and a lower survival rate (18). Our study demonstrated that NFE2L2 mRNA level as well as NFE2L2-regulated genes including HO1, NQO1, GCLC, MnSOD, and GpX1 were significantly decreased after burn. ...
Background:
Mitochondrial oxidative stress plays a prominent role in the development of burn-induced cardiac dysfunction. AMP-activated kinase (AMPK), an energy sensor, has a central role in the pathogenesis of heart failure. However, its role in cardiac dysfunction after burn injury is unclear. Our hypothesis is that burn injury acts through the AMPK-SIRT1-PGC1α-NFE2L2-ARE signaling pathway, leading to cardiac mitochondrial impairment, resulting in cardiac dysfunction.
Study design:
Male Sprague Dawley rats underwent sham procedure or 60% total body surface area full-thickness burn. Echocardiograms were performed 24-hour post burn. Heart tissue was harvested at 24 hours post burn for biochemistry/molecular biological analysis. AC16 cardiomyocytes were treated with either sham or burned rat serum (±AMPK inhibitor/AMPK activator/PGC1α activator) for evaluation of cardiomyocyte mitochondrial function by using seahorse in vitro.
Results:
Burn injury induced cardiac dysfunction, measured by echocardiogram. Burn injury suppressed cardiac AMPK, SIRT1 and PGC1 expression, leading to acetylation of cardiomyocyte proteins. In addition, burn injury caused NFE2L2 and NFE2L2 regulated antioxidants (HO-1, NQO1, GCLC, MnSOD and Gpx) to decrease, resulting in cardiac oxidative stress. In vitro, AMPK1 activator and PGC1α agonist treatment improved Ac16 cell mitochondrial dysfunction, while AMPK1 inhibitor treatment worsened Ac16 cellular damage.
Conclusions:
Burn induced cardiac dysfunction and cardiac mitochondrial damage occur via the AMPK-SIRT1-PGC1α-NFE2L2-ARE signaling pathway. AMPK and PGC1α agonists may be promising therapeutic agents to reverse cardiac dysfunction after burn injury.
... Nrf2 knock-out mice showed increased levels of IL-6 in dextran sulphate induced colitis (Khor et al., 2006). Some studies also depict that LPS-treated macrophages from Nrf2 knock-out mice have enhanced NFκB signaling and TNFα/IL-6 production as compared to their wild-type counterparts (Thimmulappa et al., 2006;Chen et al., 2016). Further, in hemodialysis patients, the NFκB expression is elevated along with a decreased Nrf2 expression in PBMCs (Leal et al., 2015). ...
... Our study displays lowered Nrf2 along with increased NFκB and inflammatory cytokines in monocytes of ASD patients. These observations propose that Nrf2 signaling controls NFκB expression and related inflammatory cytokines during inflammatory insult (Thimmulappa et al., 2006;Chen et al., 2016). ...
Autism spectrum disorder (ASD) is a very complex neurodevelopmental disorder characterized by deficits in social and communication skills. Innate immune cells like monocytes are believed to play a cardinal role in neuroimmune inflammation and nitrative stress. On the other hand, Nrf2, a basic leucine zipper transcription factor plays a significant role in protecting the immune cells against inflammation and oxidants. However, its role in monocytes of ASD children and typically developing control (TDC) children has not been elucidated in relation with inflammation and nitrative stress. Therefore, this study was undertaken to evaluate Nrf2 expression/activity along with parameters of inflammation (NFkB, IL-6, IL-1β) and nitrative stress (iNOS, nitrotyrosine) in monocytes of ASD/TDC children. Further, sulforaphane (SFN) was utilized as an Nrf2 activator to assess its effect on above said inflammatory and nitrative stress parameters. Our study shows that monocytes of ASD subjects have decreased Nrf2 expression/activity along with increased inflammation and nitrative stress. Further, monocytes from ASD have deficiency in induction of Nrf2 activity upon stimulation with LPS. However, activation of Nrf2 in vitro by SFN reverses LPS-induced effects on inflammation in monocytes by reduction in NFkB signaling. Further, treatment with SFN also reverses LPS-induced effects on nitrative stress (iNOS, nitrotyrosine) in monocytes of ASD subjects. This study propounds the idea that SFN protects against nitrative stress and inflammation by downregulating oxidative stress and inflammation through blockade of NFkB signaling in autistic children. This may be the reason behind reported ameliorative effects of SFN in ASD subjects.
