Impact of intestinal ischemia/reperfusion and lymph drainage on distant organs in rats

TLR4 inhibitors through inhibiting (MYD88-TRIF) pathway, protect against experimentally-induced intestinal (I/R) injury

Intestinal ischemia/reperfusion (I/R) injury is a serious condition that causes intestinal dysfunction and can be fatal. Previous research has shown that toll-like receptor 4 (TLR4) inhibitors have a protective effect against this injury. This study aimed to investigate the protective effects of TLR4 inhibitors, specifically cyclobenzaprine, ketotifen, amitriptyline, and naltrexone, in rats with intestinal (I/R) injury. Albino rats were divided into seven groups: vehicle control, sham-operated, I/R injury, I/R-cyclobenzaprine (10 mg/kg body weight), I/R-ketotifen (1 mg/kg body weight), I/R-amitriptyline (10 mg/kg body weight), and I/R-naltrexone (4 mg/kg body weight) groups. Anesthetized rats (urethane 1.8 g/kg) underwent 30 min of intestinal ischemia by occluding the superior mesenteric artery (SMA), followed by 2 h of reperfusion. Intestinal tissue samples were collected to measure various parameters, including malondialdehyde (MDA), nitric oxide synthase (NO), myeloperoxidase (MPO), superoxide dismutase (SOD), TLR4, intercellular adhesion molecule-1 (ICAM-1), nuclear factor kappa bp65 (NF-ĸBP65), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), macrophages CD68, myeloid differentiation factor 88 (MYD88), and toll interleukin receptor-domain-containing adaptor-inducing interferon β (TRIF). The use of TLR4 inhibitors significantly reduced MDA, MPO, and NO levels, while increasing SOD activity. Furthermore, it significantly decreased TLR4, ICAM-1, TNF-α, MCP-1, MYD88, and TRIF levels. These drugs also showed partial restoration of normal cellular structure with reduced inflammation. Additionally, there was a decrease in NF-ĸBP65 and macrophages CD68 staining compared to rats in the I/R groups. This study focuses on how TLR4 inhibitors enhance intestinal function and protect against intestinal (I/R) injury by influencing macrophages CD86 through (MYD88-TRIF) pathway, as well as their effects on oxidation and inflammation.

Gut lymph purification alleviates acute lung injury induced by intestinal ischemia-reperfusion in rats by removing danger-associated molecular patterns from gut lymph

Background

The potential effect of removing danger-associated molecular patterns (DAMPs) from gut lymph on reducing acute lung injury (ALI) induced by gut ischemia-reperfusion injury (GIRI) is uncertain. This study aimed to investigate whether gut lymph purification (GLP) could improve GIRI-induced acute lung injury in rats by clearing danger-associated molecular patterns.

Materials and methods

Rats were divided into four groups: Sham, GIRI, GIRI + gut lymph drainage (GLD), and GIRI + GLP. After successful modeling, lung tissue samples were collected from rats for hematoxylin-eosin (HE) staining and detection of apoptotic indexes. We detected the DAMPs levels in blood and lymph samples. We observed the microstructure of AEC Ⅱ and measured the expression levels of apoptosis indexes.

Results

The GIRI group showed destruction of alveolar structure, thickened alveolar walls, and inflammatory cell infiltration. This was accompanied by significantly increased levels of high mobility group protein-1 (HMGB-1) and Interleukin-6 (IL-6), while reduced levels of heat shock protein 70 (HSP 70) and Interleukin-10 (IL-10) in both lymph and serum. In contrast, the lung tissue damage in the GIRI + GLP group was significantly improved compared to the GIRI group. This was evidenced by a reduction in the expression levels of HMGB-1 and IL-6 in both lymph and serum and an increase in HSP 70 and IL-10 levels. Additionally, organelle structure of AEC II was significantly improved in the GIRI + GLP group compared to the GIRI group.

Conclusions

GLP inhibits inflammation and cell apoptosis in GIRI-induced ALI by blocking the link between DAMPs and mononuclear phagocytes, reducing the severity of ALI.

Simvastatin protects against intestinal ischemia/reperfusion-induced pulmonary artery dysfunction

AIMS

The lung is an important target organ damage in intestinal ischemia/reperfusion (II/R), but mechanisms involved in II/R-induced pulmonary artery (PA) dysfunction, as well as its treatment, are not clear. The present study aimed to investigate the mechanisms involved in the II/R-induced PA dysfunction and a possible protective role of acute simvastatin pretreatment.

MAIN METHODS

Male Wistar rats were subjected to occlusion of the superior mesenteric artery for 45 min followed by 2 h reperfusion (II/R) or sham-operated surgery (sham). In some rats, simvastatin (20 mg/kg, oral gavage) was administrated 1 h before II/R.

KEY FINDINGS

II/R reduced acetylcholine-induced relaxation and phenylephrine-induced contraction of PA segments, which were prevented by acute simvastatin pretreatment in vivo or restored by inducible nitric oxide synthase (iNOS) inhibition in situ with 1400 W. Elevated reactive oxygen species (ROS) levels and higher nuclear translocation of nuclear factor kappa B (NFκB) subunit p65 were observed in PA of II/R rats and prevented by simvastatin. Moreover, simvastatin increased superoxide dismutase (SOD) activity and endothelial nitric oxide synthase (eNOS) expression in PA of the II/R group as well as prevented the increased levels of interleukin (IL)-1β and IL-6 in lung explants following II/R.

SIGNIFICANCE

The study suggests that pretreatment with a single dose of simvastatin prevents the II/R-induced increase of inflammatory factors and oxidative stress, as well as PA endothelial dysfunction and adrenergic hyporreactivity. Therefore, acute simvastatin administration could be therapeutic for pulmonary vascular disease in patients suffering from intestinal ischemic events.

Fluid resuscitation via colon alleviates systemic inflammation in rats with early-stage severe acute pancreatitis

Fluid resuscitation via colon (FRVC) is a complementary therapeutic procedure for early-stage cases of severe acute pancreatitis (SAP). The expression of intestinal dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) regulates systemic inflammation. This study aimed to investigate the effect of FRVC on the expression of DC-SIGN in the colon tissue of SAP rats and its effect on the early response of systemic inflammatory and multiple organ injury. SAP was induced in rats via retrograde injection of sodium taurocholate into the biliopancreatic duct. DC-SIGN expression of appeared in the proximal and distal colon. Histological characteristics and inflammatory cytokines were examined to compare the effect of FRVC and intravenous fluid resuscitation (IVFR). The results showed that DC-SIGN expression in the proximal colon increased in a time-dependent manner in the early-stage of SAP rats. FRVC inhibited DC-SIGN expression in the proximal colon. Both FRVC and IVFR alleviated histological injuries of the pancreas and colon. However, FRVC had an advantage over IVFR in alleviating lung injury and reducing serum TNF-α, IL-6 and LPS. These results suggest that FRVC treatment might help suppress systemic inflammation and prevent subsequent organ failure in early-stage SAP rats likely through inhibiting DC-SIGN expression in the proximal colon.

Protective Effects of Cinnamaldehyde against Mesenteric Ischemia-Reperfusion-Induced Lung and Liver Injuries in Rats

The aim of this study was to characterize and reveal the protective effects of cinnamaldehyde (CA) against mesenteric ischemia-reperfusion- (I/R-) induced lung and liver injuries and the related mechanisms. Sprague-Dawley (SPD) rats were pretreated for three days with 10 or 40 mg/kg/d, ig of CA, and then induced with mesenteric ischemia for 1 h and reperfusion for 2 h. The results indicated that pretreatment with 10 or 40 mg/kg of CA attenuated morphological damage in both lung and liver tissues of mesenteric I/R-injured rats. CA pretreatment significantly restored the levels of aspartate transaminase (AST) and alanine transaminase (ALT) in mesenteric I/R-injured liver tissues, indicating the improvement of hepatic function. CA also significantly attenuated the inflammation via reducing myeloperoxidase (MOP) activity and downregulating the expression of inflammation-related proteins, including interleukin-6 (IL-6), interleukin-1β (IL-1β), cyclooxygenase-2 (Cox-2), and tumor necrosis factor receptor type-2 (TNFR-2) in both lung and liver tissues of mesenteric I/R-injured rats. Pretreatment with CA significantly downregulated nuclear factor kappa B- (NF-κB-) related protein expressions (NF-κB p65, NF-κB p50, I kappa B alpha (IK-α), and inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ)) in both lung and liver tissues of mesenteric I/R-injured rats. CA also significantly downregulated the protein expression of p53 family members, including caspase-3, caspase-9, Bax, and p53, and restored Bcl-2 in both lung and liver tissues of mesenteric I/R-injured rats. CA pretreatment significantly reduced TUNEL-apoptotic cells and significantly inhibited p53 and NF-κB p65 nuclear translocation in both lung and liver tissues of mesenteric I/R-injured rats. CA neither induced pulmonary and hepatic histological alterations nor affected the parameters of inflammation and apoptosis in sham rats. We conclude that CA alleviated mesenteric I/R-induced pulmonary and hepatic injuries via attenuating apoptosis and inflammation through inhibition of NF-κB and p53 pathways in rats, suggesting the potential role of CA in remote organ ischemic injury protection.

Activation of G protein-coupled estrogen receptor protects intestine from ischemia/reperfusion injury in mice by protecting the crypt cell proliferation

The intestinal ischemia/reperfusion (I/R) injury is a common clinical event related with high mortality in patients undergoing surgery or trauma. Estrogen exerts salutary effect on intestinal I/R injury, but the receptor type is not totally understood. We aimed to identify whether the G protein-coupled estrogen receptor (GPER) could protect the intestine against I/R injury and explored the mechanism. Adult male C57BL/6 mice were subjected to intestinal I/R injury by clamping (45 min) of the superior mesenteric artery followed by 4 h of intestinal reperfusion. Our results revealed that the selective GPER blocker abolished the protective effect of estrogen on intestinal I/R injury. Selective GPER agonist G-1 significantly alleviated I/R-induced intestinal mucosal damage, neutrophil infiltration, up-regulation of TNF-α and cyclooxygenase-2 (Cox-2) expression, and restored impaired intestinal barrier function. G-1 could ameliorate the impaired crypt cell proliferation ability induced by I/R and restore the decrease in villus height and crypt depth. The up-regulation of inducible nitric oxide synthase (iNOS) expression after I/R treatment was attenuated by G-1 administration. Moreover, selective iNOS inhibitor had a similar effect with G-1 on promoting the proliferation of crypt cells in the intestinal I/R model. Both GPER and iNOS were expressed in leucine-rich repeat containing G-protein coupled receptor 5 (Lgr5) positive stem cells in crypt. Together, these findings demonstrate that GPER activation can prompt epithelial cell repair following intestinal injury, which occurred at least in part by inhibiting the iNOS expression in intestinal stem cells (ISCs). GPER may be a novel therapeutic target for intestinal I/R injury.

More of the Gut in the Lung: How Two Microbiomes Meet in ARDS

In critically ill patients, lung and gut microbiomes undergo profound changes. Lung microbiome might become enriched with gut-associated microbes as recently demonstrated in sepsis and acute respiratory distress syndrome (ARDS). It has been proposed that in these conditions, bacteria from the gut might enter the lungs via translocation, a process facilitated by increased gut and alveolo-capillary permeability. In patients requiring mechanical ventilation after severe trauma, lung microbiome enrichment with gut-associated microbes was found to correlate with the development of ARDS. The lungs in ARDS are increasingly susceptible to opportunistic infections which can further perpetuate alveolar inflammation and injury. Undoubtedly, more research on the gut-lung crosstalk in critically ill patients is needed to identify causal relationships between the altered microbiome, infections, inflammation, and acute lung injury. With further insights, this area of investigation could lead to the development of novel, microbiome-targeted, and immunomodulation strategies with the potential to improve outcomes of critically ill patients with sepsis, trauma, and ARDS.

Diazoxide reduces local and remote organ damage in a rat model of intestinal ischemia reperfusion

BACKGROUND

Intestinal ischemia reperfusion is a common clinical condition that causes functional impairment. Once tight junctions are damaged, barrier function is compromised, and the intestines become a source for entry of bacterial and inflammatory mediators into the circulation, leading to systemic inflammatory response syndrome, multiple organ failure, and death. It is possible that diazoxide could protect the intestines against ischemia reperfusion. The aim of this study is to determine whether diazoxide can provide protection in a rat model of intestinal ischemia reperfusion.

METHODS

A total of 32 adult male specific pathogen-free Wistar rats were randomized into three groups: a control group, n = 6; a saline group, n = 13; and a diazoxide group, n = 13. The saline and diazoxide groups underwent clamping of the superior mesenteric artery for 1 h, with samples in all the groups being collected 12 h later.

RESULTS

Intestinal histology showed greater damage in the intestinal ischemia reperfusion groups. mRNA expression of zonula occludens-1 and occludin (tight junction proteins) and interleukin-6 and cyclooxygenase-2 was the highest in the Saline group. The Diazoxide group showed a reduction in aspartate aminotransferase serum levels compared with the other groups.

CONCLUSIONS

Increased expression of zonula occludens-1, occludin, and cyclooxygenase-2 suggested a greater regenerative effort because of more severe lesions in the saline group. In addition, increased expression of interleukin-6 in the saline group was suggestive of inflammation, indicating that diazoxide had protective effects in the diazoxide group. Reduced aspartate aminotransferase in the diazoxide group suggested liver protection. Diazoxide protects the intestines and liver from intestinal ischemia reperfusion lesions in rats.

Schisandrin B Prevents Hind Limb from Ischemia-Reperfusion-Induced Oxidative Stress and Inflammation via MAPK/NF-κB Pathways in Rats

Schisandrin B (ScB), isolated from Schisandra chinensis (S. chinensis), is a traditional Chinese medicine with proven cardioprotective and neuroprotective effects. However, it is unclear whether ScB also has beneficial effects on rat hind limb ischemia/reperfusion (I/R) injury model. In this study, ScB (20 mg/kg, 40 mg/kg, and 80 mg/kg) was administered via oral gavage once daily for 5 days before the surgery. After 6 h ischemia and 24 h reperfusion of left hind limb, ScB reduced I/R induced histological changes and edema. ScB also suppressed the oxidative stress through decreasing MDA level and increasing SOD activity. Moreover, above changes were associated with downregulated TNF-α mRNA expression and reduced level of IL-1β in plasma. Meanwhile, ScB treatment downregulated activation of p38MAPK, ERK1/2, and NF-κB in ischemic skeletal muscle. These results demonstrate that ScB treatment could prevent hind limb I/R skeletal muscle injury possibly by attenuating oxidative stress and inflammation via p38MAPK, ERK1/2, and NF-κB pathways.

Inhibition of P38 MAPK Downregulates the Expression of IL-1β to Protect Lung from Acute Injury in Intestinal Ischemia Reperfusion Rats

Acute lung injury (ALI) induced by intestinal ischemia/reperfusion (II/R) has high incidence and mortality, in which IL-1β was essential for the full development of ALI. However, the detailed regulating mechanism for this phenomenon remains to be unclear. The purpose of this study was to investigate whether inhibition of P38 MAPK could downregulate the expression of IL-1β to protect lung from acute injury in II/R rats. Here, we found that the level of pulmonary edema at 16 hours after operation (hpo) was obviously enhanced compared to that in 8hpo and sham groups. Immunofluorescent staining demonstrated that IL-1β and P38 MAPK were detected in lung tissues. And rats with II/R have the highest translation level for IL-1β and phosphorylation of P38 MAPK in lung tissues at 16hpo compared with 8hpo and sham groups. Moreover, administration of SB239063, an inhibitor of P38 α and β, could effectively downregulate the expressions of IL-1β and protects lung tissues from injury in II/R rats. Our findings indicate that the inhibition of P38 α and β may downregulate the expression of IL-1β to protect lung from acute injury in II/R, which could be used as a potential target for reducing ALI induced by II/R in the future clinical trial.

Evaluation of Pulmonary Reperfusion Injury in Rats Undergoing Mesenteric Ischemia and Reperfusion and Protective Effect of Postconditioning on this Process

INTRODUCTION

Some publications have demonstrated the presence of lung reperfusion injury in mesenteric ischemia and reperfusion (I/R), but under to diverse methods. Postconditioning has been recognized as effective in preventing reperfusion injury in various organs and tissues. However, its effectiveness has not been evaluated in the prevention of lung reperfusion injury after mesenteric ischemia and reperfusion.

OBJECTIVE

To evaluate the presence of pulmonary reperfusion injury and the protective effect of ischemic postconditioning on lung parenchyma in rats submitted to mesenteric ischemia and reperfusion.

METHODS

Thirty Wistar rats were distributed into three groups: group A (10 rats), which was held mesenteric ischemia (30 minutes) and reperfusion (60 minutes); group B (10 rats), ischemia and reperfusion, interspersed by postconditioning with two alternating cycles of reperfusion and reocclusion, for two minutes each; and group C (10 rats), ischemia and reperfusion interleaved by postconditioning with four alternating cycles of reperfusion and reocclusion of 30 seconds each. Finally, it was resected the upper lung lobe for histological analysis.

RESULTS

There were mild lung lesions (grade 1) in all samples. There was no statistical difference between groups 1 and 2 (P>0.05).

CONCLUSION

The mesenteric ischemia and reperfusion in rats for thirty and sixty minutes, respectively, caused mild reperfusion injury in lung. Postconditioning was not able to minimize the remote reperfusion injury and there was no difference comparing two cycles of two minutes with four cycles of 30 seconds.

Inflammatory mediators in intra-abdominal sepsis or injury - a scoping review

Introduction

Inflammatory and protein mediators (cytokine, chemokine, acute phase proteins) play an important, but still not completely understood, role in the morbidity and mortality of intra-abdominal sepsis/injury. We therefore systematically reviewed preclinical and clinical studies of mediators in intra-abdominal sepsis/injury in order to evaluate their ability to: (1) function as diagnostic/prognostic biomarkers; (2) serve as therapeutic targets; and (3) illuminate the pathogenesis mechanisms of sepsis or injury-related organ dysfunction.

Methods

We searched MEDLINE, PubMed, EMBASE and the Cochrane Library. Two investigators independently reviewed all identified abstracts and selected articles for full-text review. We included original studies assessing mediators in intra-abdominal sepsis/injury.

Results

Among 2437 citations, we selected 182 studies in the scoping review, including 79 preclinical and 103 clinical studies. Serum procalcitonin and C-reactive protein appear to be useful to rule out infection or monitor therapy; however, the diagnostic and prognostic value of mediators for complications/outcomes of sepsis or injury remains to be established. Peritoneal mediator levels are substantially higher than systemic levels after intra-abdominal infection/trauma. Common limitations of current studies included small sample sizes and lack of uniformity in study design and outcome measures. To date, targeted therapies against mediators remain experimental.

Conclusions

Whereas preclinical data suggests mediators play a critical role in intra-abdominal sepsis or injury, there is no consensus on the clinical use of mediators in diagnosing or managing intra-abdominal sepsis or injury. Measurement of peritoneal mediators should be further investigated as a more sensitive determinant of intra-abdominal inflammatory response. High-quality clinical trials are needed to better understand the role of inflammatory mediators.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1093-4) contains supplementary material, which is available to authorized users.

Severe Acute Pancreatitis: Gut Barrier Failure, Systemic Inflammatory Response, Acute Lung Injury, and the Role of the Mesenteric Lymph

BACKGROUND

Severe acute pancreatitis (AP) often leads to distant organ dysfunction with a high morbidity and mortality rate. The most common and earliest organ to fail is the lungs, but the exact pathophysiological mechanisms underlying the disease are still unclear. No successful targeted therapy exists, and treatment is limited to organ supportive care. It is believed that the gut is involved in the development of distant organ failure, as severe AP is associated with changes in the microcirculation, gut permeability/motility, bacterial translocation, and activation of the gut-associated lymphoid tissue (GALT). Experimental evidence implicates the mesenteric lymph as a primary route for these toxic factors to gain access to the systemic circulation. This literature overview was made to survey these mechanisms and the potential of surgical interventions on the thoracic duct as a means of therapy.

METHODS

Review of the pertinent English-language literature.

RESULTS

In experimental studies, interruption of mesenteric lymphatic flow has preventive qualities for acute lung injury (ALI) in the setting of critical illness with various etiologies. Experimentally, diversion of mesenteric lymph is able to prevent ALI if done before its development, whereas a later intervention partially reduces the lung damage. Few studies have investigated surgical approaches to the thoracic duct in human beings under these circumstances, and the ones that have been performed are of low quality and have conflicting results. It seems likely that the intervention would need to be performed prior to the development of ALI to obtain maximum benefits, which complicates its application clinically, because prediction of ALI cannot today be done with high precision.

CONCLUSION

Studies are ongoing to identify the factors carried in mesenteric lymph that may cause end-organ failure (e.g., ALI) and, once recognized, might allow the development of novel targeted agents that would modify the disease course.

Monitoring dynamic alterations in calcium homeostasis by T1-mapping manganese-enhanced MRI (MEMRI) in the early stage of small intestinal ischemia-reperfusion injury

Manganese-enhanced MRI studies have proven to be useful in monitoring physiological activities associated with calcium ions (Ca(2+)) due to the paramagnetic property of the manganese ion (Mn(2+)), which makes it an excellent probe of Ca(2+) . In this study, we developed a method in which a Mn(2+)-enhanced T1 -map MRI could enable the monitoring of Ca(2+) influx during the early stages of intestinal ischemia-reperfusion (I/R) injury. The Mn(2+) infusion protocol was optimized by obtaining dose-dependent and time-course wash-out curves using a Mn(2+)-enhanced T1-map MRI of rabbit abdomens following an intravenous infusion of 50 mmol/l MnCl2 (5-10 nmol/g body weight (BW)). In the rabbit model of intestinal I/R injury, T1 values were derived from the T1 maps in the intestinal wall region and revealed a relationship between the dose of the infused MnCl2 and the intestinal wall relaxation time. Significant Mn(2+) clearance was also observed over time in control animals after the infusion of Mn(2+) at a dose of 10 nmol/g BW. This technique was also shown to be sensitive enough to monitor variations in calcium ion homeostasis in vivo after small intestinal I/R injury. The T1 values of the intestinal I/R group were significantly lower (P < 0.05) than that of the control group at 5, 10, and 15 min after Mn(2+) infusion. Our data suggest that MnCl2 has the potential to be an MRI contrast agent that can be effectively used to monitor changes in intracellular Ca(2+) homeostasis during the early stages of intestinal I/R injury.

TLR4-HMGB1-, MyD88- and TRIF-dependent signaling in mouse intestinal ischemia/reperfusion injury

AIM: To characterize high-mobility group protein 1-toll-like receptor 4 (HMGB1-TLR4) and downstream signaling pathways in intestinal ischemia/reperfusion (I/R) injury.

METHODS: Forty specific-pathogen-free male C57BL/6 mice were randomly divided into five groups (n = 8 per group): sham, control, anti-HMGB1, anti-myeloid differentiation gene 88 (MyD88), and anti-translocating-chain-associating membrane protein (TRIF) antibody groups. Vehicle with the control IgG antibody, anti-HMGB1, anti-MyD88, or anti-TRIF antibodies (all 1 mg/kg, 0.025%) were injected via the caudal vein 30 min prior to ischemia. After anesthetization, the abdominal wall was opened and the superior mesenteric artery was exposed, followed by 60 min mesenteric ischemia and then 60 min reperfusion. For the sham group, the abdominal wall was opened for 120 min without I/R. Levels of serum nuclear factor (NF)-κB p65, interleukin (IL)-6, and tumor necrosis factor (TNF)-α were measured, along with myeloperoxidase activity in the lung and liver. In addition,morphologic changes that occurred in the lung and intestinal tissues were evaluated. Levels of mRNA transcripts encoding HMGB1 and NF-κB were measured by real-time quantitative PCR, and levels of HMGB1 and NF-κB protein were measured by Western blot. Results were analyzed using one-way analysis of variance.

RESULTS: Blocking HMGB1, MyD88, and TRIF expression by injecting anti-HMGB1, anti-MyD88, or anti-TRIF antibodies prior to ischemia reduced the levels of inflammatory cytokines in serum; NF-κB p65: 104.64 ± 11.89, 228.53 ± 24.85, 145.00 ± 33.63, 191.12 ± 13.22, and 183.73 ± 10.81 (P < 0.05); IL-6: 50.02 ± 6.33, 104.91 ± 31.18, 62.28 ± 6.73, 85.90 ± 17.37, and 78.14 ± 7.38 (P < 0.05); TNF-α, 43.79 ± 4.18, 70.81 ± 6.97, 52.76 ± 5.71, 63.19 ± 5.47, and 59.70 ± 4.63 (P < 0.05) for the sham, control, anti-HMGB1, anti-MyD88, and anti-TRIF groups, respectively (all in pg/mL).Antibodies also alleviated tissue injury in the lung and small intestine compared with the control group in the mouse intestinal I/R model. The administration of anti-HMGB1, anti-MyD88, and anti-TRIF antibodies markedly reduced damage caused by I/R, for which anti-HMGB1 antibody had the most obvious effect.

CONCLUSION: HMGB1 and its downstream signaling pathway play important roles in the mouse intestinal I/R injury, and the effect of the TRIF-dependent pathway is slightly greater.

The significance and mechanism of propofol on treatment of ischemia reperfusion induced lung injury in rats

This study is aimed to investigate the efficacy and underlying the mechanism of propofol in treatment of ischemia reperfusion (IR)-induced lung injury in rats, providing a novel insight of therapeutic strategy for IR-induced lung injury. 120 healthy SD rats were selected and randomly divided into sham operation group, IR group, and propofol group (40 rats per group). Bronchoalveolar lavage fluid (BALF) protein content, serum protein content, lung permeability index, lung water content rate, methane dicarboxylic aldehyde (MDA) in lung tissue, superoxide dismutase (SOD), nitric oxide (NO), endothelin (ET-1), toll-like receptor 4 (TLR4), nuclear factor (NF-κB), and tumor necrosis factor-α (TNF-α) were examined and compared among different groups to evaluate the therapeutical effects of propofol on IR-induced lung injury and analyze the mechanism. In sham operation group, neither change in lung tissue nor pulmonary interstitial edema or alveolar wall damage was found under microscope; in IR group, marked pulmonary interstitial edema and alveolar wall damage complicated with inflammatory cell infiltration and hemorrhage were found; in propofol group, alveolar wall widening was observed, however, hemorrhage in alveolar cavity, inflammatory infiltration and tissue damage were less significant than in IR group. At 3 h after reperfusion, BALF protein content, lung permeability index, and lung water content rate were all significantly increased in IR group and propofol group, while the serum protein content was significantly lower than sham operation group (p < 0.05). Moreover, we found that the change of above parameters in propofol group was less significant than in IR group (p < 0.05). No statistically significant difference was found in ET-1 levels in different groups (p > 0.05). In contrast, MDA and NO in IR group and propofol group were significantly increased, while SOD activity was significantly decreased (p < 0.05). Furthermore, the change of above parameters in propofol group was less significant than in IR group (p < 0.05). In addition, mRNAs of TLR4, NF-κB, and TNF-α were significantly increased in IR group and propofol group (p < 0.05) with more significant change in IR group compared with propofol group (p < 0.05). Propofol has protective effects against IR-induced lung injury by improving activity of oxygen radical and restoring NO/ET-1 dynamic balance. Besides, regulation of TLR4, NF-κB, and TNF-α by propofol also play important role in alleviating IR-induced lung injury.

Oxidative stress-mediated HMGB1 biology

High mobility group box 1 (HMGB1) is a widely-expressed and highly-abundant protein that acts as an extracellular signal upon active secretion by immune cells or passive release by dead, dying, and injured cells. Both intracellular and extracellular HMGB1 play pivotal roles in regulation of the cellular response to stress. Targeting the translocation, release, and activity of HMGB1 can limit inflammation and reduce tissue damage during infection and sterile inflammation. Although the mechanisms contributing to HMGB1 biology are still under investigation, it appears that oxidative stress is a central regulator of HMGB1's translocation, release, and activity in inflammation and cell death (e.g., necrosis, apoptosis, autophagic cell death, pyroptosis, and NETosis). Thus, targeting HMGB1 with antioxidant compounds may be an attractive therapeutic strategy for inflammation-associated diseases such as sepsis, ischemia and reperfusion injury, arthritis, diabetes, and cancer.

Continuous hemodiafiltration therapy reduces damage of multi-organs by ameliorating of HMGB1/TLR4/NFκB in a dog sepsis model

In the present study, we investigated whether CVVH can reduce HMGB1, TLR4, NF-κB and other serum cytokine levels, preventing organ injury in a dog sepsis model. A total of 10 dogs were injected with LPS and treated with either CVVH group (n = 5) or nothing (Control, n = 5) for 24 h. EILSA was used for examining the concentration of TNF-α, IL-6, HMGB 1 and TLR4. The histological change of lung, liver and kidney tissues was determined. The mRNA expression of HMGB1, TLR4 and NF-κB was examined by RT-PCR. The protein of HMGB1 and phosphated NF-κB was examined by Western-blot. The levels of serum HMGB1 came to the peak at 8 h, 16 h and then declined. The LPS-induced increase in HMGB1 level was suppressed by CVVH compared with Control. Likewise, serum TNF-α and IL-6 levels decreased with CVVH along with a significant improvement in the function of main organs. Histologic examination revealed significant reduction in inflammation in lung; liver and kidney tissues harvested 24 h after CVVH compared with Control. The mRNA of HMGB1, TLR4 and NF-κB in the kidney was expressed at high level after LPS administration, which was significantly decreased by CVVH. The increased protein expression of HMGB1 and phosphated NF-κB was reduced after CVVH compared with control. CVVH by reducing the level of HMGB1, TLR4, NF-κB and other cytokines could weaken the cascade of cytokines and restore the immune system, and reduce the damage of important organs in sepsis.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Mesenteric lymph reperfusion exacerbates spleen injury caused by superior mesenteric artery occlusion shock

The intestinal lymph pathway plays an important role in the pathogenesis of organ injury following superior mesenteric artery occlusion (SMAO) shock. We hypothesized that mesenteric lymph reperfusion (MLR) is a major cause of spleen injury after SMAO shock. To test this hypothesis, SMAO shock was induced in Wistar rats by clamping the superior mesenteric artery (SMA) for 1 h, followed by reperfusion for 2 h. Similarly, MLR was performed by clamping the mesenteric lymph duct (MLD) for 1 h, followed by reperfusion for 2 h. In the MLR+SMAO group rats, both the SMA and MLD were clamped and then released for reperfusion for 2 h. SMAO shock alone elicited: 1) splenic structure injury, 2) increased levels of malondialdehyde, nitric oxide (NO), intercellular adhesion molecule-1, endotoxin, lipopolysaccharide receptor (CD14), lipopolysaccharide-binding protein, and tumor necrosis factor-α, 3) enhanced activities of NO synthase and myeloperoxidase, and 4) decreased activities of superoxide dismutase and ATPase. MLR following SMAO shock further aggravated these deleterious effects. We conclude that MLR exacerbates spleen injury caused by SMAO shock, which itself is associated with oxidative stress, excessive release of NO, recruitment of polymorphonuclear neutrophils, endotoxin translocation, and enhanced inflammatory responses.