THE GREEN TEA POLYPHENOL EPIGALLOCATECHIN-3-GALLATE IMPROVES SYSTEMIC HEMODYNAMICS AND SURVIVAL IN RODENT MODELS OF POLYMICROBIAL SEPSIS

Neuron-immunity communication: mechanism of neuroprotective effects in EGCG

Epigallocatechin gallate (EGCG), a naturally occurring active ingredient unique to tea, has been shown to have neuroprotective potential. There is growing evidence of its potential advantages in the prevention and treatment of neuroinflammation, neurodegenerative diseases, and neurological damage. Neuroimmune communication is an important physiological mechanism in neurological diseases, including immune cell activation and response, cytokine delivery. EGCG shows great neuroprotective potential by modulating signals related to autoimmune response and improving communication between the nervous system and the immune system, effectively reducing the inflammatory state and neurological function. During neuroimmune communication, EGCG promotes the secretion of neurotrophic factors into the repair of damaged neurons, improves intestinal microenvironmental homeostasis, and ameliorates pathological phenotypes through molecular and cellular mechanisms related to the brain-gut axis. Here, we discuss the molecular and cellular mechanisms of inflammatory signaling exchange involving neuroimmune communication. We further emphasize that the neuroprotective role of EGCG is dependent on the modulatory role between immunity and neurology in neurologically related diseases.

The effects of flavonoids in experimental sepsis: A systematic review and meta-analysis

Sepsis is a host's dysregulated immune response to an infection associated with systemic inflammation and excessive oxidative stress, which can cause multiple organ failure and death. The literature suggests that flavonoids, a broad class of secondary plant metabolites, have numerous biological activities which can be valuable in the treatment of sepsis. This study aimed to review the effects of flavonoids on experimental sepsis, focusing mainly on survival rate, and also summarizing information on its mechanisms of action. We searched in the main databases up to November 2022 using relevant keywords, and data were extracted and analyzed qualitatively and quantitatively. Thirty-two articles met the study criteria for review and 29 for meta-analysis. Overall, 30 different flavonoids were used in the studies. The flavonoids were able to strongly inhibit inflammatory response by reducing the levels of important pro-inflammatory mediators, for example, tumor necrosis factor-alpha and interleukin-1β, oxidative stress, and showed antibacterial and anti-apoptotic actions. The meta-analysis found an increase of 50% in survival rate of the animals treated with flavonoids. They appear to act as multi-target drugs and may be an excellent therapeutic alternative to reduce a number of the complications caused by sepsis, and consequently, to improve survival rate.

Potential role of herbal medicines as a novel approach in sepsis treatment

The growing number of deaths related to sepsis has become a major concern for past few years. Sepsis is a complex pathological reactions that is explained by series of host response to microbial insult. The resulted systemic reactions are manifested by early appearance of proinflammatory cytokines leading to hyperinflammatory phase which is followed by septic shock and death of the patient. The present study has revealed that antibiotics are not self-sufficient to control the complex mechanism of sepsis. Moreover prolonged and unnecessary administration of antibiotics may lead to antibiotic resistance to pathogens. In addition to this, immunosuppressive medications are selective and have targeted approach to certain study population. Drugs from herbal origin have shown to possess a mammoth of immunomodulatory potential by suppressing proinflammatory and anti-inflammatory cytokines exhibiting no or minimal unwanted secondary responses. Concomitantly, herbal plants tend to modulate oxidative stress level and haematological imbalance during inflammatory diseased conditions. Natural compounds have gained much attention for the treatment of several clinical complications. Considering the promising responses of medicinal plants with less/no side effects and easy procurement, comprehensive research on herbal plants to treat sepsis should be contemplated.

Potential protective mechanisms of green tea polyphenol EGCG against COVID-19

Background

The world is in the midst of the COVID-19 pandemic. In this comprehensive review, we discuss the potential protective effects of (−)-epigallocatechin-3-gallate (EGCG), a major constituent of green tea, against COVID-19.

Scope and approach

Information from literature of clinical symptoms and molecular pathology of COVID-19 as well as relevant publications in which EGCG shows potential protective activities against COVID-19 is integrated and evaluated.

Key findings and conclusions

EGCG, via activating Nrf2, can suppress ACE2 (a cellular receptor for SARS-CoV-2) and TMPRSS2, which mediate cell entry of the virus. Through inhibition of SARS-CoV-2 main protease, EGCG may inhibit viral reproduction. EGCG via its broad antioxidant activity may protect against SARS-CoV-2 evoked mitochondrial ROS (which promote SARS-CoV-2 replication) and against ROS burst inflicted by neutrophil extracellular traps. By suppressing ER-resident GRP78 activity and expression, EGCG can potentially inhibit SARS-CoV-2 life cycle. EGCG also shows protective effects against 1) cytokine storm-associated acute lung injury/acute respiratory distress syndrome, 2) thrombosis via suppressing tissue factors and activating platelets, 3) sepsis by inactivating redox-sensitive HMGB1, and 4) lung fibrosis through augmenting Nrf2 and suppressing NF-κB. These activities remain to be further substantiated in animals and humans. The possible concerted actions of EGCG suggest the importance of further studies on the prevention and treatment of COVID-19 in humans. These results also call for epidemiological studies on potential preventive effects of green tea drinking on COVID-19.

Tea Polyphenols Prevent Sepsis-Induced Lung Injury via Promoting Translocation of DJ-1 to Mitochondria

Background

Sepsis is the systemic inflammatory response syndrome caused by infection, which commonly targets on the lung. Tea polyphenols (TP) have many pharmacological activities, but their role in sepsis induced lung injury remains unclear.

Results

Injection of TP after cecal ligation and puncture (CLP) operation elevated the survival rate in a concentration dependent manner. TP treatment improved alveoli structure injury under CLP operation. CLP surgery increased the expression of inflammatory factors IL1β, IL6, and TNFα expression, which was reversed by TP injection. In addition, CLP operation promoted apoptosis and senescence in tissues and cells during lung injury, while TP administration removed the damaged role of CLP on lung tissues and cells. Furthermore, CLP operation or LPS (lipopolysaccharide) treatment induced dysfunction of mitochondria in lung tissues and cells, but TP contributed to recover mitochondria function, which exhibited as inhibition of ROS production inhibition and increase of ATP content and Mitochondrial membrane potential (MMP). Interestingly, DJ-1 was inhibited by CLP operation but promoted by TP treatment. Overexpression of DJ-1 reversed the injury of LPS on L2 cells and recovered mitochondria normal function. And silencing of DJ-1 in rats or alveolar epithelial cells blocked the protection effect of TP.

Conclusion

Our research revealed that TP protected against lung injury via upregulating of DJ-1 to improve mitochondria function, which contributed to the prevention and treatment of sepsis induced lung injury.

The role of phytochemicals in sepsis: A mechanistic and therapeutic perspective

Sepsis and septic shock are still a leading cause of mortality and morbidity in intensive care units worldwide. Sepsis is an uncontrolled and excessive response of the innate immune system toward the invading infectious microbes, characterized by the hyper-production of pro-inflammatory mediators such as interleukin (IL)-1β, IL-6, tumor-necrosis factor (TNF)-α, and high-mobility group box 1 (HMGB1). In severe sepsis, the overwhelming production of pro-inflammatory cytokines and reactive oxygen species may compromise organ function and lead to the induction of abnormal apoptosis in different organs, resulting in multiple organ dysfunction syndrome and death. Hence, compounds that are able to attenuate inflammatory responses may have therapeutic potential for sepsis treatment. Understanding the pathophysiology and underlying molecular mechanisms of sepsis may provide useful insights in the discovery and development of new effective therapeutics. Therefore, numerous studies have invested much effort into elucidating the mechanisms involved with the onset and development of sepsis. The present review mainly focuses on the molecules and signaling pathways involved in the pathogenicity of sepsis. Additionally, several well-known natural bioactive herbal compounds and phytochemicals, which have shown protective and therapeutic effects with regard to sepsis, as well as their mechanisms of action, are presented. This review suggests that these phytochemicals are able to attenuate the overwhelming inflammatory responses developed during sepsis by modulating different signaling pathways. Moreover, the anti-inflammatory and cytoprotective activities of phytochemicals make them potent compounds to be included as complementary therapeutic agents in the diets of patients suffering from sepsis in an effort to alleviate sepsis and its life-threatening complications, such as multi-organ failure.

Protective Effect of Epigallocatechin-3-Gallate (EGCG) in Diseases with Uncontrolled Immune Activation: Could Such a Scenario Be Helpful to Counteract COVID-19?

Some coronavirus disease 2019 (COVID-19) patients develop acute pneumonia which can result in a cytokine storm syndrome in response to Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) infection. The most effective anti-inflammatory drugs employed so far in severe COVID-19 belong to the cytokine-directed biological agents, widely used in the management of many autoimmune diseases. In this paper we analyze the efficacy of epigallocatechin 3-gallate (EGCG), the most abundant ingredient in green tea leaves and a well-known antioxidant, in counteracting autoimmune diseases, which are dominated by a massive cytokines production. Indeed, many studies registered that EGCG inhibits signal transducer and activator of transcription (STAT)1/3 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcription factors, whose activities are crucial in a multiplicity of downstream pro-inflammatory signaling pathways. Importantly, the safety of EGCG/green tea extract supplementation is well documented in many clinical trials, as discussed in this review. Since EGCG can restore the natural immunological homeostasis in many different autoimmune diseases, we propose here a supplementation therapy with EGCG in COVID-19 patients. Besides some antiviral and anti-sepsis actions, the major EGCG benefits lie in its anti-fibrotic effect and in the ability to simultaneously downregulate expression and signaling of many inflammatory mediators. In conclusion, EGCG can be considered a potential safe natural supplement to counteract hyper-inflammation growing in COVID-19.

The Metabolic Basis of Immune Dysfunction Following Sepsis and Trauma

Critically ill, severely injured and high-risk surgical patients are vulnerable to secondary infections during hospitalization and after hospital discharge. Studies show that the mitochondrial function and oxidative metabolism of monocytes and macrophages are impaired during sepsis. Alternatively, treatment with microbe-derived ligands, such as monophosphoryl lipid A (MPLA), peptidoglycan, or β-glucan, that interact with toll-like receptors and other pattern recognition receptors on leukocytes induces a state of innate immune memory that confers broad-spectrum resistance to infection with common hospital-acquired pathogens. Priming of macrophages with MPLA, CPG oligodeoxynucleotides (CpG ODN), or β-glucan induces a macrophage metabolic phenotype characterized by mitochondrial biogenesis and increased oxidative metabolism in parallel with increased glycolysis, cell size and granularity, augmented phagocytosis, heightened respiratory burst functions, and more effective killing of microbes. The mitochondrion is a bioenergetic organelle that not only contributes to energy supply, biosynthesis, and cellular redox functions but serves as a platform for regulating innate immunological functions such as production of reactive oxygen species (ROS) and regulatory intermediates. This review will define current knowledge of leukocyte metabolic dysfunction during and after sepsis and trauma. We will further discuss therapeutic strategies that target leukocyte mitochondrial function and might have value in preventing or reversing sepsis- and trauma-induced immune dysfunction.

l-theanine alleviates liver and kidney dysfunction in septic rats induced by cecal ligation and puncture

AIMS

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response against infection that triggers systemic inflammatory response syndrome. l-theanine (LT), a glutamate derivative, is a non-protein amino acid derived from tea (Camellia sinensis), and a valuable nutraceutical product used as an additive in the food industry. This study we aimed to investigate whether LT would exert any therapeutic effect on liver and kidney tissues in Sprague Dawley rats with sepsis induced with cecal ligation and puncture (CLP).

MAIN METHODS

Rats were divided into four groups; sham, CLP, CLP+LT1 (2x250 mg/kg) and CLP+LT2 (2 × 750 mg/kg). Liver and kidney tissues were subjected to histopathological examination. Apoptotic index percentages (AI%) were examined using the TUNEL method. The oxidized glutathione to total glutathione (GSSG/TGSH) ratio (as a marker of oxidative stress, levels of caspase-3 (a marker of apoptosis), glutathione peroxidase (GPx) and glutathione S-transferase (GST) (as antioxidant enzymes), inducible nitric oxide synthase (iNOS) and the tumor necrosis factor-α to Interleukin-10 ratio (TNF-α/IL-10) (as markers of inflammation) were investigated using commercial kits. Levels of malondialdehyde (MDA) (a marker of oxidative stress) were determined spectrophotometrically.

KEY FINDINGS

A high dose of LT exhibited more significant effects in reducing oxidative stress, inflammation and apoptosis than a low dose of LT in liver and kidney tissues with CLP-induced sepsis (p < 0.05).

SIGNIFICANCE

Our results indicated that LT significantly and dose-dependently inhibited sepsis induced liver and kidney injury. This effect may be attributed to the antioxidant, anti-inflammatory, and anti-apoptotic activities of LT.

TLR4 Signaling Pathway Modulators as Potential Therapeutics in Inflammation and Sepsis

Toll-Like Receptor 4 (TLR4) signal pathway plays an important role in initiating the innate immune response and its activation by bacterial endotoxin is responsible for chronic and acute inflammatory disorders that are becoming more and more frequent in developed countries. Modulation of the TLR4 pathway is a potential strategy to specifically target these pathologies. Among the diseases caused by TLR4 abnormal activation by bacterial endotoxin, sepsis is the most dangerous one because it is a life-threatening acute system inflammatory condition that still lacks specific pharmacological treatment. Here, we review molecules at a preclinical or clinical phase of development, that are active in inhibiting the TLR4-MyD88 and TLR4-TRIF pathways in animal models. These are low-molecular weight compounds of natural and synthetic origin that can be considered leads for drug development. The results of in vivo studies in the sepsis model and the mechanisms of action of drug leads are presented and critically discussed, evidencing the differences in treatment results from rodents to humans.

Apigenin Alleviates Endotoxin-Induced Myocardial Toxicity by Modulating Inflammation, Oxidative Stress, and Autophagy

Apigenin, a component in daily diets, demonstrates antioxidant and anti-inflammatory properties. Here, we intended to explore the mechanism of apigenin-mediated endotoxin-induced myocardial injury and its role in the interplay among inflammation, oxidative stress, and autophagy. In our lipopolysaccharide- (LPS-) induced myocardial injury model, apigenin ameliorated cardiac injury (lactate dehydrogenase (LDH) and creatine kinase (CK)), cell death (TUNEL staining, DNA fragmentation, and PARP activity), and tissue damage (cardiac troponin I (cTnI) and cardiac myosin light chain-1 (cMLC1)) and improved cardiac function (ejection fraction (EF) and end diastolic left ventricular inner dimension (LVID)). Apigenin also alleviated endotoxin-induced myocardial injury by modulating oxidative stress (nitrotyrosine and protein carbonyl) and inflammatory cytokines (TNF-α, IL-1β, MIP-1α, and MIP-2) along with their master regulator NFκB. Apigenin modulated redox homeostasis, and its anti-inflammatory role might be associated with its ability to control autophagy. Autophagy (determined by LAMP1, ATG5, and p62), its transcriptional regulator transcription factor EB (TFEB), and downstream target genes including vacuolar protein sorting-associated protein 11 (Vps11) and microtubule-associated proteins 1A/1B light chain 3B (Map1lc3) were modulated by apigenin. Thus, our study demonstrated that apigenin may lead to potential development of new target in sepsis treatment or other myocardial oxidative and/or inflammation-induced injuries.

EGCG induces G-CSF expression and neutrophilia in experimental sepsis

A major green tea component, epigallocatechin-3-gallate (EGCG), has been proven protective against lethal sepsis in experimental setting, but its protective mechanisms remain incompletely understood. Here, we provide evidence to support EGCG's capacities in stimulating G-CSF production and neutrophilia in vivo. In an animal model of sepsis, EGCG significantly elevated peritoneal levels of G-CSF and several chemokines (e.g., MCP-1/CCL2 and MIP-1γ/CCL9), and consequently increased peritoneal neutrophil numbers (neutrophilia) at a late stage. In vitro, EGCG divergently affected HMGB1-mediated production of several chemokines: reducing CXCL15 and RANTES/CCL5, but elevating G-CSF and MIP-1α/CCL3 production by peritoneal macrophages. Similarly, it significantly induced the expression and secretion of G-CSF and MIP-1α/CCL3 in human peripheral blood mononuclear cells. Based on our preliminary data, it may be important to search for anti-inflammatory and G-CSF-stimulating agents for the clinical management of inflammatory diseases.

Glycyrrhizin protects against porcine endotoxemia through modulation of systemic inflammatory response

INTRODUCTION

Glycyrrhizin (GL) was recently found to suppress high-mobility group box 1 (HMGB1)-induced injury by binding directly to it. However, the effect of GL on HMGB1 expression in endotoxemia as well as its underlying molecular mechanism remained unclear.

METHODS

Twenty-one pigs were divided into four groups: sham group (n=3), control group (n=6), ethyl pyruvate group (n=6) and glycyrrhizin group (n=6). Pigs were anesthetized, mechanically ventilated, monitored and given a continuous intravenous infusion of lipopolysaccharide (LPS). Twelve hours after the start of the LPS infusion, ethyl pyruvate (30 mg/kg/hr) or glycyrrhizin (1 mg/kg/hr) was administered for 12 hours. Systemic and pulmonary hemodynamics, oxygen exchange, and metabolic status were measured. The concentrations of cytokines in serum and the corresponding gene and protein expressions in tissue samples from liver, lungs, kidneys, small intestine and lymph nodes were measured.

RESULTS

GL maintained the stability of systemic hemodynamics and improved pulmonary oxygen exchange and metabolic status. GL also attenuated organ injury and decreased the serum levels of HMGB1 and other pro-inflammatory cytokines by inhibiting their gene and protein expression.

CONCLUSIONS

GL improved systemic hemodynamics and protected vital organs against porcine endotoxemia through modulation of the systemic inflammatory response. By reducing the serum level and gene expression of HMGB1 and other pro-inflammatory cytokines, GL may become a potential agent for the treatment of sepsis.

Positive effect of septimeb™ on mortality rate in severe sepsis: a novel non antibiotic strategy

Background

Septimeb is a new herbal-derived remedy, recently approved for its potential immunomodulatory effects. Regarding the key role of immune system in the pathogenesis of severe sepsis and lack of any standard treatment for improving survival of these patients; we evaluated the effect of Septimeb -as an adjutant to standard treatment-on inflammatory biomarkers and mortality rates in patients with severe sepsis.

Methods

In this multicenter, randomized, single-blind trial, we assigned patients with severe sepsis and Acute Physiology and Chronic Health Evaluation (APACHE II) score of more than 20 to receive standard treatment of severe sepsis (control group) or standard treatment plus Septimeb. This group was treated with Septimeb for 14 days then followed up for another14 days. APACHE score, Sequential Organ Failure Assessment (SOFA) and Simplified Acute Physiology Score (SAPS) were calculated daily. Blood samples were analyzed for interleukin 2 tumor necrosis factor-α, total antioxidant power, platelet growth factor and matrix metalloproteinase 2.

Results

A total of 29 patients underwent randomization (13 in control group and 16 in Septimeb group). There was significant difference between the Septimeb and control group in the 14 days mortality rate (18.8% vs. 53.85 respectively, P=0.048). Compared to control group, Septimeb was significantly effective in improving SAPS (P= 0.029), SOFA (P=0.003) and APACHE II (P=0.008) scores. Inflammatory biomarkers didn’t change significantly between the two groups (P>0.05).

Conclusion

Septimeb reduces mortality rates among patients with severe sepsis and it could be added as a safe adjutant to standard treatment of sepsis.

Cecal ligation and puncture: the gold standard model for polymicrobial sepsis?

Sepsis is a serious medical condition characterized by dysregulated systemic inflammatory responses followed by immunosuppression. To study the pathophysiology of sepsis, diverse animal models have been developed. Polymicrobial sepsis induced by cecal ligation and puncture (CLP) is the most frequently used model because it closely resembles the progression and characteristics of human sepsis. Here we summarize the role of several immune components in the pathogenesis of sepsis induced by CLP. However, several therapies proposed on the basis of promising results obtained by CLP could not be translated to the clinic. This demonstrates that experimental sepsis models do not completely mimic human sepsis. We propose several strategies to narrow the gap between experimental sepsis models and clinical sepsis, including targeting factors that contribute to the immunosuppressive phase of sepsis, and reproducing the heterogeneity of human patients.

Effects of flavonoids and other polyphenols on inflammation

Flavonoids are a family of polyphenolic compounds which are widespread in nature (vegetables) and are consumed as part of the human diet in significant amounts. There are other types of polyphenols, including, for example, tannins and resveratrol. Flavonoids and related polyphenolic compounds have significant antiinflammatory activity, among others. This short review summarizes the current knowledge on the effects of flavonoids and related polyphenolic compounds on inflammation, with a focus on structural requirements, the mechanisms involved, and pharmacokinetic considerations. Different molecular (cyclooxygenase, lipoxygenase) and cellular targets (macrophages, lymphocytes, epithelial cells, endothelium) have been identified. In addition, many flavonoids display significant antioxidant/radical scavenging properties. There is substantial structural variation in these compounds, which is bound to have an impact on their biological profile, and specifically on their effects on inflammatory conditions. However, in general terms there is substantial consistency in the effects of these compounds despite considerable structural variations. The mechanisms have been studied mainly in myeloid cells, where the predominant effect is an inhibition of NF-κB signaling and the downregulation of the expression of proinflammatory markers. At present there is a gap in knowledge of in vitro and in vivo effects, although the pharmacokinetics of flavonoids has advanced considerably in the last decade. Many flavonoids have been studied for their intestinal antiinflammatory activity which is only logical, since the gastrointestinal tract is naturally exposed to them. However, their potential therapeutic application in inflammation is not restricted to this organ and extends to other sites and conditions, including arthritis, asthma, encephalomyelitis, and atherosclerosis, among others.

LPS pretreatment ameliorates multiple organ injuries and improves survival in a murine model of polymicrobial sepsis

OBJECTIVE

The endotoxin tolerance phenotype is characterized with decreased inflammation and increased phagocytosis. We hypothesized that endotoxin tolerance would provide protective effects on experimental sepsis with multiple organ injuries induced by cecal ligation and puncture (CLP).

METHODS

Endotoxin tolerance was induced in male Sprague-Dawley rats with daily intraperitoneal injection of either 0.6 mg/kg of lipopolysaccharide (LPS) or vehicle for four consecutive days before subsequent CLP. Biochemical parameters, histological changes, inflammatory cytokine production, and lung tissue nuclear factor-κB (NF-κB) activation were assessed post-CLP. In a separate experiment, survival rate was monitored for 7 days after CLP.

RESULTS

In vehicle-treated animals, CLP caused multiple organ injuries confirmed by the biochemical variables and histological examination. This was accompanied by an early activation of NF-κB in the lung and a substantial increase in plasma levels of tumor necrosis factor-α, interleukin-6, and interleukin-10. In contrast, pretreatment with LPS not only alleviated the development of multiple organ injuries after CLP, but also decreased sepsis-induced activation of pulmonary NF-κB and reduced plasma cytokines production. In addition, LPS pretreatment improved the survival in rats subjected to CLP.

CONCLUSIONS

The beneficial effects of endotoxin tolerance indicate the potential of immunomodulatory strategies in the management of severe sepsis.

Riboflavin protects mice against liposaccharide-induced shock through expression of heat shock protein 25

Riboflavin (vitamin B2) is a water-soluble vitamin essential for normal cellular functions, growth and development. This study aimed to investigate the effects of vitamin B2 on the survival rate, and expressions of tissue heat shock protein 25 (HSP25) and heat shock factor 1 (HSF1) in mice undergoing lipopolysaccharide (LPS) induced shock. Mice were assigned to four groups, saline vehicle, LPS, LPS plus low dose of vitamin B2 (LB2) and LPS plus high dose of vitamin B2 (HB2). Vitamin B2 (1 and 10mg/kg BW) was administered intraperitoneally at 2 and 0 h before the i.p. administration of LPS. At the end of the experiment, the survival rate monitored was 10, 20, 60, and 100% for LPS, LB2, HB2, and saline mice, respectively. HSP25 expressions in the heart and lung were significantly enhanced in a time-dependent manner in the HB2 mice as compared to the saline mice (p < 0.05), but not altered in the LB2 mice. In the HB2 mice, plasma riboflavin concentrations reached 300 nM at 6h post LPS and returned to the 0 h level at 72 h. The results showed that high dose of riboflavin could decrease LPS-induced mortality through an increased expression of HSP25.

High mobility group box 1 protein as a potential drug target for infection- and injury-elicited inflammation

In response to infection or injury, a ubiquitous nucleosomal protein, HMGB1 is secreted actively by innate immune cells, and / or released passively by injured/damaged cells. Subsequently, extracellular HMGB1 alerts, recruits, and activates various innate immune cells to sustain a rigorous inflammatory response. A growing number of HMGB1 inhibitors ranging from neutralizing antibodies, endogenous hormones, to medicinal herb-derived small molecule HMGB1 inhibitors (such as nicotine, glycyrrhizin, tanshinones, and EGCG) are proven protective against lethal infection and ischemic injury. Here we review emerging evidence that support extracellular HMGB1 as a proinflammatory alarmin(g) danger signal, and discuss a wide array of HMGB1 inhibitors as potential therapeutic agents for sepsis and ischemic injury.

Anti-inflammatory intestinal activity of Abarema cochliacarpos (Gomes) Barneby & Grimes in TNBS colitis model

AIM OF THE STUDY

To assess the anti-inflammatory effect of butanolic fraction of methanolic extract from bark of Abarema cochliacarpos in acute ulcerative colitis model induced by intracolonic administration of trinitrobenzene sulfonic acid (TNBS) in Wistar rats.

MATERIALS AND METHODS

Abarema cochliacarpos (100 and 150mg/kg/day) was administered by gavage 48, 24 and 1h prior to the induction of colitis with 10mg/kg of TNBS and, 24h later.

RESULTS

Phytochemical studies by mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR) revealed that catechins were a major component into condensate class of tannins. Treatment with Abarema cochliacarpos decreased significantly macroscopic damage as compared with TNBS (p<0.05). Histological analysis showed that both doses of the extract improved the microscopic structure and preserved some areas of the colonic mucosa structure. In addition, myeloperoxidase activity (MPO), as a marker of neutrophil infiltration, was decreased in a dose-dependent way (p<0.01 and p<0.001 respectively), TNF-alpha level was also diminished with the highest dose of the extract (p<0.001) and, IL-10 level obtained no significant results. In order to elucidate some of the mechanisms, expression of inducible inflammatory enzymes, such as cyclooxygenase (COX)-2 and nitric oxide synthase (iNOS), were studied showing a significant reduction. Finally, the involvement of c-Jun N-terminal kinase (JNK) signalling demonstrated a reduction in the JNK activation with the highest dose (p<0.05 vs TNBS).

CONCLUSIONS

We have shown for the first time that the extracts obtained from Abarema cochliacarpos bark possess active substances, which exert marked protective effects in acute experimental colitis, confirming and justifying, at least in part, the popular use of this plant to treat gastrointestinal diseases.

Novel HMGB1-inhibiting therapeutic agents for experimental sepsis

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. The inflammatory response is partly mediated by innate immune cells (such as macrophages, monocytes, and neutrophils), which not only ingest and eliminate invading pathogens but also initiate an inflammatory response by producing early (e.g., TNF and IFN-gamma) and late (e.g., high-mobility group box [HMGB1]) proinflammatory cytokines. Here, we briefly review emerging evidence that support extracellular HMGB1 as a late mediator of experimental sepsis and discuss therapeutic potential of several HMGB1-inhibiting agents (including neutralizing antibodies and steroid-like tanshinones) in experimental sepsis.

Rosmarinic acid protects against experimental sepsis by inhibiting proinflammatory factor release and ameliorating hemodynamics

The present study was to investigate the effects of rosmarinic acid (RA) in cultured RAW264.7 cells and experimental model of sepsis induced by cecal ligation and puncture in rats and the potential mechanism. Results showed that RA concentration dependently down-regulated the levels of TNF-alpha, IL-6, and high-mobility group box 1 protein in LPS-induced RAW264.7 cells, inhibited the IkappaB kinase pathway, and modulated nuclear factor-kappaB. Intravenous injection of RA alone or in combination with imipenem reduced cecal ligation and puncture-induced lethality in rats. In addition, serum levels of TNF-alpha, IL-6, high-mobility group box 1 protein, triggering receptor expressed on myeloid cells, and endotoxin were down-regulated; in contrast, serum level of IL-10 was up-regulated. Amelioration of hemodynamics and decrease in serum enzyme activities and myeloperoxidase in lung, liver, and small intestine were also observed after RA injection. These data indicate that the antisepsis effect of RA was mediated by decreasing local and systemic levels of a wide spectrum of inflammatory mediators. This article provides the first evidence that RA has the capacity to inactivate inflammatory response in sepsis. The anti-inflammatory mechanism of RA may inhibit activation of the nuclear factor- kappaB pathway by inhibiting IkappaB kinase activity.

NF-kappaB signaling pathway and its therapeutic implications in human diseases

The nuclear factor-kappaB (NF-kappaB) pathway is one of the most important cellular signal transduction pathways involved in both physiologic processes and disease conditions. It plays important roles in the control of immune function, inflammation, stress response, differentiation, apoptosis, and cell survival. Moreover, NF-kappaB is critically involved in the processes of development and progression of cancers. More importantly, recent studies have shown that NF-kappaB signaling also plays critical roles in the epithelial-mesenchymal transition (EMT) and cancer stem cells. Therefore, targeting of NF-kappaB signaling pathway could be a potent strategy for the prevention and/or treatment of human cancers and inflammatory diseases.

Enhancement of NF-kappaB activation in lymphocytes prevents T cell apoptosis and improves survival in murine sepsis

Sepsis induces extensive lymphocyte apoptosis that contributes to immunosuppression and mortality. Activation of the canonical NF-kappaB pathway, however, prevents TNF-alpha-induced lymphocyte apoptosis. In this study the function of canonical NF-kappaB in T cells was studied in the context of murine sepsis. Upon cecal ligation and puncture (CLP), NF-kappaB DNA binding activity in thymocytes declines relative to sham-operated mice. This decline in NF-kappaB activity is most likely due to posttranslational modifications such as deacetylation of p65. In parallel, cleavage of procaspase-3 is increased, whereas expression of NF-kappaB-dependent antiapoptotic genes Bcl-xL and c-IAP2 is suppressed upon sepsis induction. Interestingly, adoptive transfer of IkappaBalpha-deficient fetal liver stem cells into sublethally irradiated lymphopenic host mice reduced the decline in thymocyte survival, increased peripheral T cell numbers, and improved the mortality rate relative to wild-type reconstituted hosts after cecal ligation and puncture. In conclusion, lymphocyte-directed augmentation of canonical NF-kappaB ameliorates immunosuppression during murine sepsis. These data provide evidence for a new approach in sepsis therapy.

Therapeutic effect of epigallocatechin-3-gallate in a mouse model of colitis

Epigallocatechin-3-gallate (EGCG), a green tea catechin, has been shown to inhibit signaling pathways involved in inflammation, including nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1), which are important inducers of pro-inflammatory mediators. Aim of our study was to evaluate the therapeutic efficacy of EGCG in experimental colitis, which was induced by rectal administration of trinitrobenzenesulfonic acid (TNBS) in C57/BL6 mice. Mice were treated twice daily with vehicle or with EGCG (10 mg/kg) intraperitoneally, and sacrificed on days 1, 3, and 7 after TNBS administration. After induction of colitis, vehicle-treated mice experienced bloody diarrhea and loss of body weight. A remarkable colonic damage with hemorrhage, ulcers, and edema was observed and was associated with neutrophil infiltration as evaluated by myeloperoxidase (MPO) activity. Elevated plasma levels of tumor necrosis factor alpha, interleukin (IL)-6, IL-10 and keratinocyte-derived chemokine were also found. These events were paralleled by increased DNA binding of NF-kappaB and AP-1 in the colon of the vehicle-treated group. In contrast, the EGCG-treated mice experienced a very mild diarrhea and no weight loss. Damage of the colon was characterized by edema and hyperemia only. Tissue levels of MPO were also significantly reduced when compared to vehicle-treated mice. These beneficial effects of EGCG were associated with a significant reduction of NF-kappaB and AP-1 activation. However, treatment with EGCG did not reduce plasma cytokine levels. Our data demonstrate that EGCG may be beneficial in colitis through selective immunomodulatory effects, which may be mediated, at least in part, by inhibition of NF-kappaB and AP-1.