Hindlimb ischemia/reperfusion-induced remote injury to the small intestine: role of inducible nitric-oxide synthase-derived nitric oxide

Immunomodulatory efficacy of Cousinia thomsonii C.B. Clarke in ameliorating inflammatory cascade expressions

ETHNOPHARMACOLOGICAL RELEVANCE

Cousinia thomsonii is traditionally known for treating various diseases including joint pain, swelling, body ache, asthma, dermatitis, cough and arthritis.

AIM OF THE STUDY

This study employs lipopolysaccharide induced inflammatory wistar-rat model to evaluate efficacy of Cousinia thomsonii active-extracts on the expression of crucial inflammatory markers viz. iNOS, PPAR-γ, Rel-A, COX-2 and serum analysis of CRP.

MATERIALS AND METHODS

Methanol and aqueous extracts were administered orally at 25, 50, 100 mg/kg doses for 21 days. Serum was collected on 22nd day and rats were sacrificed to extract paw tissues. Dexamethasone (0.5 mg/kg) served as positive control. Immunoblotting and qPCR was used for expression analysis of iNOS, PPAR-γ, Rel-A, COX-2 respectively. ELISA was employed for evaluating CRP levels. Discovery-studio and Auto-Dock-Vina were used to check docking interactions of various identified compounds.

RESULTS

Both extracts caused dose-dependent decline in iNOS, Rel-A, COX-2 and CRP levels, while there was a dose-dependent increase in PPAR-γ expression. Methanol extract dominated immunomodulatory potential as compared with the aqueous extract. The results of the GCMS revealed the presence of ten compounds. Some of these compounds include 1-Octacosanol, Ethyl Linoleate, 1-Heptacosanol, 1-Hexadecanol, 1-Dodecanol and Behenic alcohol having strong anti-inflammatory, antimicrobial, anti-acne and anti-viral activities. Molecular Docking scores were calculated between each target protein and selected compounds. The best affinity/interactions were observed between 1-Octacosanol towards iNOS, PPAR-γ, Rel-A, COX-2 and CRP with binding energy of -10.4, -11.1, -8.6, -9.9 and -7.9 (kcal/mol) respectively. These compounds may act as strong inhibitors for iNOS, Rel-A, COX-2 and CRP or as agonists for PPAR-γ; thereby inducing anti-inflammatory/immuno-modulatory activities.

CONCLUSIONS

The results indicate that Cousinia thomsonii contains therapeutically active compounds and thus could serve as potential therapeutic regimen against diverse inflammatory diseases.

Modulation of oxidative–nitrosative stress and inflammatory response by rapamycin in target and distant organs in rats exposed to hindlimb ischemia–reperfusion: the role of mammalian target of rapamycin

Mammalian target of rapamycin (mTOR) has been recognized with potential immunomodulatory properties playing an important role in various physiopathological processes including ischemia–reperfusion (I/R) injury. I/R injury stimulate reactive oxygen and nitrogen species by activating nicotinamide adenine dinucleotide phosphate oxidase and inducible nitric oxide synthase, respectively. Controversial results have been obtained in different I/R models following localized I/R; however, the precise role of the mTOR signaling pathway remains undefined. The objective of the current study was to evaluate the role of the mTOR in oxidative–nitrosative stress and inflammation in hindlimb I/R-induced injury in target and remote organ injuries. In rats subjected to I/R, an increased expression of ribosomal protein S6 (rpS6), inhibitor κB (IκB)-α, nuclear factor-κB (NF-κB) p65, inducible nitric oxide synthase, cyclooxygenase 2, gp91phox, and levels of tumor necrosis factor α, nitrite, nitrotyrosine, malondialdehyde and the activities of myeloperoxidase and catalase in the tissues and (or) sera were detected. Treatment with rapamycin, a selective inhibitor of mTOR, reversed all the I/R-induced changes as manifested by its anti-inflammatory and antioxidant effects in kidney and gastrocnemius muscle of rats. Collectively, these findings suggest that rapamycin protects against I/R-induced oxidative–nitrosative stress and inflammation leading to organ injuries via suppression of mTOR/IκB-α/NF-κB signaling pathway.

Inducible nitric oxide synthase contributes to insulin resistance and cardiac dysfunction after burn injury in mice

AIMS

Cardiac dysfunction is a major cause of multi-organ dysfunction in critical care units following severe burns. The purpose of this study was to investigate the role of inducible nitric oxide synthase (iNOS) in cardiac dysfunction in burned mice.

MATERIALS AND METHODS

Wild-type and iNOS-knockout mice were subjected to 30% total body surface area burns. Next, the expression of iNOS was measured at 1, 3 and 7 days post-burn. Cardiac function, insulin sensitivity, inflammation, oxidative stress, and apoptosis in the hearts of the mice were assessed at 3 days post-burn.

KEY FINDINGS

Compared to control mice, iNOS expression was increased and reached a maximum in the heart of burned mice at 3 days post-burn. iNOS deficiency significantly alleviated the cardiac dysfunction and insulin resistance in burned mice. In addition, burn-induced inflammation, oxidative stress, and apoptosis in the heart were markedly reduced in iNOS-knockout burned mice when compared to corresponding values in wild-type burned mice.

SIGNIFICANCE

Our study demonstrates that iNOS contributes to insulin resistance in the hearts of mice following burn injury, and iNOS deficiency protects cardiac function against burn injury in mice, suggesting iNOS as a potential therapeutic target to treat burn injuries.

The nitric oxide synthase 2 pathway is targeted by both pro- and anti-inflammatory treatments in the immature human intestine

BACKGROUND AND AIM

NO synthase 2 (NOS2) was recently identified as one the most overexpressed genes in intestinal samples of premature infants with necrotizing enterocolitis (NEC). NOS2 is widely implicated in the processes of epithelial cell injury/apoptosis and host immune defense but its specific role in inflammation of the immature human intestinal mucosa remains unclear. Interestingly, factors that prevent NEC such as epidermal growth factor (EGF) attenuate the inflammatory response in the mid-gestation human small intestine using serum-free organ culture while drugs that are associated with NEC occurrence such as the non-steroidal anti-inflammatory drug, indomethacin (INDO), exert multiple detrimental effects on the immature human intestine. In this study we investigate the potential role of NOS2 in modulating the gut inflammatory response under protective and stressful conditions by determining the expression profile of NOS2 and its downstream pathways in the immature intestine.

METHODS

Gene expression profiles of cultured mid-gestation human intestinal explants were investigated in the absence or presence of a physiological concentration of EGF (50 ng/ml) or 1 μM INDO for 48 h using Illumina whole genome microarrays, Ingenuity Pathway Analysis software and quantitative PCR to investigate the expression of NOS2 and NOS2-pathway related genes.

RESULTS

In the immature intestine, NOS2 expression was found to be increased by EGF and repressed by INDO. Bioinformatic analysis identified differentially regulated pathways where NOS2 is known to play an important role including citrulline/arginine metabolism, epithelial cell junctions and oxidative stress. At the individual gene level, we identified many differentially expressed genes of the citrulline/arginine metabolism pathway such as ARG1, ARG2, GLS, OAT and OTC in response to EGF and INDO. Gene expression of tight junction components such as CLDN1, CLDN2, CLDN7 and OCN and of antioxidant markers such as DUOX2, GPX2, SOD2 were also found to be differentially modulated by EGF and INDO.

CONCLUSION

These results suggest that the protective effect of EGF and the deleterious influence of INDO on the immature intestine could be mediated via regulation of NOS2. Pathways downstream of NOS2 involved with these effects include metabolism linked to NO production, epithelial barrier permeability and antioxidant expression. These results suggest that NOS2 is a likely regulator of the inflammatory response in the immature human gut and may provide a mechanistic basis for the protective effect of EGF and the deleterious effects of INDO.

iNOS as a Driver of Inflammation and Apoptosis in Mouse Skeletal Muscle after Burn Injury: Possible Involvement of Sirt1 S-Nitrosylation-Mediated Acetylation of p65 NF-κB and p53

Inflammation and apoptosis develop in skeletal muscle after major trauma, including burn injury, and play a pivotal role in insulin resistance and muscle wasting. We and others have shown that inducible nitric oxide synthase (iNOS), a major mediator of inflammation, plays an important role in stress (e.g., burn)-induced insulin resistance. However, it remains to be determined how iNOS induces insulin resistance. Moreover, the interrelation between inflammatory response and apoptosis is poorly understood, although they often develop simultaneously. Nuclear factor (NF)-κB and p53 are key regulators of inflammation and apoptosis, respectively. Sirt1 inhibits p65 NF-κB and p53 by deacetylating these transcription factors. Recently, we have shown that iNOS induces S-nitrosylation of Sirt1, which inactivates Sirt1 and thereby increases acetylation and activity of p65 NF-κB and p53 in various cell types, including skeletal muscle cells. Here, we show that iNOS enhances burn-induced inflammatory response and apoptotic change in mouse skeletal muscle along with S-nitrosylation of Sirt1. Burn injury induced robust expression of iNOS in skeletal muscle and gene disruption of iNOS significantly inhibited burn-induced increases in inflammatory gene expression and apoptotic change. In parallel, burn increased Sirt1 S-nitrosylation and acetylation and DNA-binding capacity of p65 NF-κB and p53, all of which were reversed or ameliorated by iNOS deficiency. These results indicate that iNOS functions not only as a downstream effector but also as an upstream enhancer of burn-induced inflammatory response, at least in part, by Sirt1 S-nitrosylation-dependent activation (acetylation) of p65 NF-κB. Our data suggest that Sirt1 S-nitrosylation may play a role in iNOS-mediated enhanced inflammatory response and apoptotic change, which, in turn, contribute to muscle wasting and supposedly to insulin resistance after burn injury.

Compartment syndrome causes systemic inflammation in a rat

Aims

Compartment syndrome results from increased intra-compartmental pressure (ICP) causing local tissue ischaemia and cell death, but the systemic effects are not well described. We hypothesised that compartment syndrome would have a profound effect not only on the affected limb, but also on remote organs.

Methods

Using a rat model of compartment syndrome, its systemic effects on the viability of hepatocytes and on inflammation and circulation were directly visualised using intravital video microscopy.

Results

We found that hepatocellular injury was significantly higher in the compartment syndrome group (192 PI-labelled cells/10-1 mm3, standard error of the mean (sem) 51) compared with controls (30 PI-labelled cells/10-1 mm3, sem 12, p < 0.01). The number of adherent venular white blood cells was significantly higher for the compartment syndrome group (5 leukocytes/30s/10 000 μm2, sem 1) than controls (0.2 leukocytes/30 s/10 000 μm2, sem 0.2, p < 0.01). Volumetric blood flow was not significantly different between the two groups, although there was an increase in the heterogeneity of perfusion.

Conclusions

Compartment syndrome can be accompanied by severe systemic inflammation and end organ damage. This study provides evidence of the relationship between compartment syndrome in a limb and systemic inflammation and dysfunction in a remote organ. Cite this article: Bone Joint J 2016; 98-B:1132–7.

Inflammatory stimuli induce inhibitory S-nitrosylation of the deacetylase SIRT1 to increase acetylation and activation of p53 and p65

Inflammation increases the abundance of inducible nitric oxide synthase (iNOS), leading to enhanced production of nitric oxide (NO), which can modify proteins by S-nitrosylation. Enhanced NO production increases the activities of the transcription factors p53 and nuclear factor κB (NF-κB) in several models of disease-associated inflammation. S-nitrosylation inhibits the activity of the protein deacetylase SIRT1. SIRT1 limits apoptosis and inflammation by deacetylating p53 and p65 (also known as RelA), a subunit of NF-κB. We showed in multiple cultured mammalian cell lines that NO donors or inflammatory stimuli induced S-nitrosylation of SIRT1 within CXXC motifs, which inhibited SIRT1 by disrupting its ability to bind zinc. Inhibition of SIRT1 reduced deacetylation and promoted activation of p53 and p65, leading to apoptosis and increased expression of proinflammatory genes. In rodent models of systemic inflammation, Parkinson's disease, or aging-related muscular atrophy, S-nitrosylation of SIRT1 correlated with increased acetylation of p53 and p65 and activation of p53 and NF-κB target genes, suggesting that S-nitrosylation of SIRT1 may represent a proinflammatory switch common to many diseases and aging.

Pretreatment with mineralocorticoid receptor blocker reduces intestinal injury induced by ischemia and reperfusion: involvement of inhibition of inflammatory response, oxidative stress, nuclear factor κB, and inducible nitric oxide synthase

BACKGROUND

Spironolactone (Sp), a mineralocorticoid receptor antagonist, protects against the ischemia reperfusion (IR) injury of retina, kidney, heart, and brain. We aimed to investigate the effects of Sp on intestinal IR injury.

METHODS

Male Wistar rats were randomly divided into: (1) a sham control group; (2) an IR control group, subjected to 30 min ischemia and 3 h reperfusion; (3) a group treated with Sp (20 mg/kg) for 3 d before the IR; and (4) a sham-operated control group treated with Sp (20 mg/kg). After the reperfusion, blood and intestinal tissue samples were collected to evaluate histopathologic state, neutrophil infiltration (by measuring myeloperoxidase activity), levels of the cytokines (tumor necrosis factor α, interleukin 1α [IL-1α], interferon γ, monocyte chemotactic protein-1, granulocyte macrophage-colony stimulating factor, and IL-4), malondialdehyde (MDA) and reduced glutathione contents, and immunohistochemical expressions of nuclear factor κB, inducible nitric oxide synthase (iNOS), and caspase-3.

RESULTS

MDA content, myeloperoxidase activity, and plasma levels of tumor necrosis factor α, IL-1α, and monocyte chemotactic protein-1 were all elevated in IR, indicating the oxidative stress and local and systemic inflammatory response. Sp administration markedly reduced the MDA content and the cytokine levels. The pretreatment alleviated intestinal injury, neutrophil infiltration, and the expressions of caspase-3, iNOS, and NFκB.

CONCLUSIONS

The results implicate that Sp may have a strong protective effect against the intestinal IR injury. The effect can be mediated via suppression of both systemic inflammatory response and apoptosis through amelioration of oxidative stress and generation of proinflammatory cytokines, iNOS, caspase-3, and nuclear factor κB. Therefore, mineralocorticoid receptor antagonism might be of potential therapeutic benefit in cases of intestinal IR damage.

Contribution of RhoA/Rho-kinase/MEK1/ERK1/2/iNOS pathway to ischemia/reperfusion-induced oxidative/nitrosative stress and inflammation leading to distant and target organ injury in rats

The small G protein RhoA and its downstream effector Rho-kinase play an important role in various physiopathological processes including ischemia/reperfusion (I/R) injury. Reactive oxygen and nitrogen species produced by iNOS and NADPH oxidase are important mediators of inflammation and organ injury following an initial localized I/R event. The aim of this study was to determine whether RhoA/Rho-kinase signaling pathway increases the expression and activity of MEK1, ERK1/2, iNOS, gp91(phox), and p47(phox), and peroxynitrite formation which result in oxidative/nitrosative stress and inflammation leading to hindlimb I/R-induced injury in kidney as a distant organ and gastrocnemius muscle as a target organ. I/R-induced distant and target organ injury was performed by using the rat hindlimb tourniquet model. I/R caused an increase in the expression and/or activity of RhoA, MEK1, ERK1/2, iNOS, gp91(phox), p47(phox), and 3-nitrotyrosine and nitrotyrosine levels in the tissues. Although Rho-kinase activity was increased by I/R in the kidney, its activity was decreased in the muscle. Serum and tissue MDA levels and MPO activity were increased following I/R. I/R also caused an increase in SOD and catalase activities associated with decreased GSH levels in the tissues. Y-27632, a selective Rho-kinase inhibitor, (100µg/kg, i.p.; 1h before reperfusion) prevented the I/R-induced changes except Rho-kinase activity in the muscle. These results suggest that activation of RhoA/Rho-kinase/MEK1/ERK1/2/iNOS pathway associated with oxidative/nitrosative stress and inflammation contributes to hindlimb I/R-induced distant organ injury in rats. It also seems that hindlimb I/R induces target organ injury via upregulation of RhoA/MEK1/ERK1/2/iNOS pathway associated with decreased Rho-kinase activity.

Nitric oxide-supplemented resuscitation improves early gastrointestinal blood flow in rats subjected to hemorrhagic shock without late consequences

BACKGROUND

we have shown that hemorrhage/resuscitation altered gastrointestinal blood flow (GI-BF) and that gastric perfusion did not recover after resuscitation. This study aimed to determine the effect of nitric oxide (NO) supplemented resuscitation on the mean arterial blood pressure (MAP), GI-BF, and outcome after hemorrhagic shock.

METHODS

rats were subjected to hemorrhage and resuscitation with/without the NO-donor S-nitroso human serum albumin (S-NO-HSA). GI-BF was determined using colored microspheres.

RESULTS

NO supplementation significantly decreased MAP at the end of resuscitation. At the same time point, the GI-BF has significantly increased in the stomach, duodenum, and colon. Two hours after treatment discontinuation, there was no difference in either MAP or GI-BF between NO-supplemented and control groups. The survival times indicated that S-NO-HSA treatment was noninferior compared with control.

CONCLUSIONS

NO-supplemented resuscitation improves the GI-BF during the early stage of resuscitation without a negative impact on short-/long-term survival despite a transient MAP decrease.

Carbon monoxide liberated from CO-releasing molecule (CORM-2) attenuates ischemia/reperfusion (I/R)-induced inflammation in the small intestine

CORM-released CO has been shown to be beneficial in resolution of acute inflammation. The acute phase of intestinal ischemia-reperfusion (I/R) injury is characterized by oxidative stress-related inflammation and leukocyte recruitment. In this study, we assessed the effects and potential mechanisms of CORM-2-released CO in modulation of inflammatory response in the small intestine following I/R-challenge. To this end mice (C57Bl/6) small intestine were challenged with ischemia by occluding superior mesenteric artery (SMA) for 45 min. CORM-2 (8 mg/kg; i.v.) was administered immediately before SMA occlusion. Sham operated mice were injected with vehicle (0.25% DMSO). Inflammatory response in the small intestine (jejunum) was assessed 4 h following reperfusion by measuring tissue levels of TNF-alpha protein (ELISA), adhesion molecules E-selectin and ICAM-1 (Western blot), NF-kappaB activation (EMSA), along with PMN tissue accumulation (MPO assay) and leukocyte rolling/adhesion in the microcirculation of jejunum (intravital microscopy). The obtained results indicate that tissue levels of TNF-alpha, E-selectin and ICAM-1 protein expression, activation of NF-kappaB, and subsequent accumulation of PMN were elevated in I/R-challenged jejunum. The above changes were significantly attenuated in CORM-2-treated mice. Taken together these findings indicate that CORM-2-released CO confers anti-inflammatory effects by interfering with NF-kappaB activation and subsequent up-regulation of vascular pro-adhesive phenotype in I/R-challenged small intestine.