Effects of green tea catechins on the pro-inflammatory response after haemorrhage/resuscitation in rats

The roles of catechins in regulation of systemic inflammation

Catechins are a phytochemical present in plants such as tea leaves, beans, black grapes, cherries, and cacao, and have various physiological activities. It is reported that catechins have a health improvement effect and ameliorating effect against various diseases. In addition, antioxidant activity, liver damage prevention, cholesterol lowering effect, and anti-obesity activity were confirmed through in vivo animal and clinical studies. Although most diseases are reported as ones mediating various inflammations, the mechanism for improving inflammation remains unclear. Therefore, the current review article evaluates the physiological activity and various pharmacological actions of catechins and conclude by confirming an improvement effect on the inflammatory response.

A Comprehensive Review of the Potential Use of Green Tea Polyphenols in the Management of COVID-19

Green tea is produced from Camellia sinensis (L.) buds and leaves that have not gone through the oxidation and withering processes used to produce black and oolong teas. It was originated in China, but its cultivation and production have expanded to other Eastern Asian countries. Several polyphenolic compounds, including flavandiols, flavonols, flavonoids, and phenolic acids, are found in green tea and may constitute greater than 30% of the dry weight. Flavonols, especially catechins, represent the majority of green tea polyphenols. Green tea polyphenolic compounds have been reported to confer several health benefits. This review describes the potential use of green tea polyphenols in the management of coronavirus disease 2019 (COVID-19). The immunomodulatory, antibacterial, antioxidant, and anti-inflammatory effects of green tea polyphenols have also been considered in this review. In addition to describing the bioactivities associated with green tea polyphenols, this review discusses the potential delivery of these biomolecules using a nanoparticle drug delivery system. Moreover, the bioavailability and toxicity of green tea polyphenols are also evaluated.

Research progress on the potential delaying skin aging effect and mechanism of tea for oral and external use

Skin aging is characterized by the gradual loss of elasticity, the formation of wrinkles and various color spots, the degradation of extracellular matrix proteins, and the structural changes of the dermis. With the increasingly prominent problems of environmental pollution, social pressure, ozone layer thinning and food safety, skin problems have become more and more complex. The skin can reflect the overall health of the body. Skincare products for external use alone cannot fundamentally solve skin problems; it needs to improve the overall health of the body. Based on the literature review in recent 20 years, this paper systematically reviewed the potential delaying effect of tea and its active ingredients on skin aging by oral and external use. Tea is the second-largest health drink after water. It is rich in tea polyphenols, l-theanine, tea pigments, caffeine, tea saponins, tea polysaccharides and other secondary metabolites. Tea and its active substances have whitening, nourishing, anti-wrinkle, removing spots and other skincare effects. Its mechanism of action is ultraviolet absorption, antioxidant, anti-inflammatory, inhibition of extracellular matrix aging, inhibiting the accumulation of melanin and toxic oxidation products, balancing intestinal and skin microorganisms, and improving mood and sleep, among other effects. At present, tea elements skincare products are deeply loved by consumers. This paper provides a scientific theoretical basis for tea-assisted beauty and the high-end application of tea in skincare products.

Inhibition effect of epigallocatechin-3-gallate on the pharmacokinetics of calcineurin inhibitors, tacrolimus, and cyclosporine A, in rats

BACKGROUND

Epigallocatechin-3-gallate (EGCG) is the most biologically active catechin of green tea. Tacrolimus (TAC) and cyclosporine A (CsA) are immunosuppressive agents commonly used in clinical organ transplantation. The present study investigated the effect of EGCG on the pharmacokinetics of TAC and CsA in rats and its underlying mechanisms.

RESEARCH DESIGN AND METHODS

Either TAC or CsA was administered to rats intravenously or orally with or without concomitant EGCG. Polymerase Chain Reaction and Western Blot were used to determine the effect of EGCG on drug-metabolizing enzymes (DMEs), drug transporters (DTs) and nuclear receptors (NRs).

RESULTS

The C_max and AUC of TAC were reduced, and V/F and CL/F of TAC were enhanced after co-administration of EGCG. EGCG increased the Cmax, AUC of CsA at 3 ~ 30 mg∙kg-1 dosages, while decreased those parameters at the dosage of 100 mg∙kg-1. EGCG inhibited the mRNA and protein expressions of DMEs and DTs, such as CYP3A1, A2, UGT1A1, Mdr1 and Mrp2, but upregulated the expressions of Car, Pxr and Fxr.

CONCLUSIONS

These results revealed consumption of high dose EGCG may cause a significant alteration in pharmacokinetics of TAC and distribution/elimination profiles of CsA through the regulation of DMEs, DTs and NRs.

Ethyl Pyruvate Reduces Systemic Leukocyte Activation via Caspase-1 and NF-κB After Blunt Chest Trauma and Haemorrhagic Shock

Background: Blunt chest (thoracic) trauma (TxT) and haemorrhagic shock with subsequent resuscitation (H/R) induce strong systemic and local inflammatory response, which is closely associated with apoptotic cell loss and subsequently impaired organ function. The underlying mechanisms are not completely understood, therefore, the treatment of patients suffering from TxT+H/R is challenging. In our recent studies, we have demonstrated local anti-inflammatory effects of ethyl pyruvate (EtP) in lung and liver after TxT+H/R. Here, the therapeutic potential of a reperfusion regime with EtP on the early post-traumatic systemic inflammatory response and apoptotic changes after TxT followed by H/R were investigated.

Methods: Female Lewis rats underwent TxT followed by haemorrhagic shock (60 min). Resuscitation was performed with own blood transfusion and either lactated Ringers solution (LR) or LR supplemented with EtP (50 mg/kg). Sham group underwent the surgical procedures. After 2 h blood as well as lung and liver tissues were obtained for analyses. Systemic activation of neutrophils (expression of CD11b and CD62L), leukocyte phagocytosis, apoptosis (caspase-3/7 activation), pyroptosis (caspase-1 activation) and NF-κB p65 activity were assessed. p < 0.05 was considered significant.

Results: TxT+H/R-induced systemic activation of neutrophils (increased CD11b and reduced CD62L expression) was significantly reduced by EtP. Trauma-induced delayed neutrophil apoptosis was further reduced by EtP reperfusion but remained unaltered in monocytes. Reperfusion with EtP significantly increased the phagocytizing capacity of granulocytes. Trauma-induced inflammasome activation, which was observed in monocytes and not in neutrophils, was significantly reduced by EtP in both cell entities. NF-κB p65 activation, which was increased in neutrophils and monocytes was significantly decreased in monocytes.

Conclusion: TxT+H/R-induced systemic activation of both neutrophils and monocytes concomitant with increased systemic inflammation was reduced by a reperfusion with EtP and was associated with a down-regulation of NF-κB p65 activation.

Monotrauma is associated with enhanced remote inflammatory response and organ damage, while polytrauma intensifies both in porcine trauma model

AIM

Severely injured patients experience substantial immunological stress upon traumatic insult. Next to the direct local tissue injury also other organs, which are not directly injured such as liver and lung, are frequently affected by a so-called remote organ damage (ROD) after trauma. Thus, we studied the inflammatory response of lung and liver either after isolated femur fracture as example for ROD, or after multiple trauma in a porcine polytrauma model.

METHODS

Twenty-four male pigs (Sus scrofa) underwent either isolated standardized femoral fracture (monotrauma, MT, n = 12) or polytrauma (PT, n = 12). PT consisted of a femur fracture, lung contusion, liver laceration, hemorrhagic shock, subsequent resuscitation and surgical fracture fixation. Six animals served as controls (sham). After 72 h inflammatory changes were determined by analyses of the interleukin (IL)-6 gene expression and tissue infiltration of polymorphonuclear leukocyte (PMN, myeloperoxidase staining). ROD in MT, and lung as well as liver damage in PT were assessed histologically by hematoxylin-eosin staining. Expression of phosphorylated p65 NF-κB was evaluated by immunohistology.

RESULTS

IL-6 increased in lungs and liver in both groups MT and PT, respectively, compared to sham. Similarly, PMN infiltration of the lungs and liver increased significantly after both MT and PT compared to sham. Histological evaluation demonstrated tissue damage notably in lungs after MT, while tissue damage after PT was found in both lung and liver after PT. p65 NF-κB tended to an increase upon MT, and was significantly enhanced after PT in both tissues.

CONCLUSION

Our data indicate that remote organ damage after MT notably in lungs was associated with an enhanced inflammatory response. Severe polytrauma substantially intensifies this response and organ damage in the underlying model.

Leukotriene B4 indicates lung injury and on-going inflammatory changes after severe trauma in a porcine long-term model

BACKGROUND

Recognizing patients at risk for pulmonary complications (PC) is of high clinical relevance. Migration of polymorphonuclear leukocytes (PMN) to inflammatory sites plays an important role in PC, and is tightly regulated by specific chemokines including interleukin (IL)-8 and other mediators such as leukotriene (LT)B4. Previously, we have reported that LTB4 indicated early patients at risk for PC after trauma. Here, the relevance of LTB4 to indicating lung integrity in a newly established long-term porcine severe trauma model (polytrauma, PT) was explored.

METHODS

Twelve pigs (3 months old, 30 ± 5kg) underwent PT including standardized femur fracture, lung contusion, liver laceration, hemorrhagic shock, subsequent resuscitation and surgical fracture fixation. Six animals served as controls (sham). After 72h lung damage and inflammatory changes were assessed. LTB4 was determined in plasma before the experiment, immediately after trauma, and after 2, 4, 24 or 72h. Bronchoalveolar lavage (BAL)-fluid was collected prior and after the experiment.

RESULTS

Lung injury, local gene expression of IL-8, IL-1β, IL-10, IL-18 and PMN-infiltration into lungs increased significantly in PT compared with sham. Systemic LTB4 increased markedly in both groups 4h after trauma. Compared with declined plasma LTB4 levels in sham, LTB4 increased further in PT after 72h. Similar increase was observed in BAL-fluid after PT.

CONCLUSIONS

In a severe trauma model, sustained changes in terms of lung injury and inflammation are determined at day 3 post-trauma. Specifically, increased LTB4 in this porcine long-term model indicated a rapid inflammatory alteration both locally and systemically. The results support the concept of LTB4 as a biomarker for PC after severe trauma and lung contusion.

Ethyl pyruvate reduces acute lung damage following trauma and hemorrhagic shock via inhibition of NF-κB and HMGB1

OBJECTIVE

After blunt thoracic trauma (TxT) and hemorrhagic shock with resuscitation (H/R) intense local inflammatory response and cell loss frequently impair the pulmonary function. Ethyl pyruvate (EP) has been reported to improve the pathophysiologic derangements in models of acute inflammation. Here, we studied the effects of EP on inflammation and lung damage after TxT+H/R.

METHODS

Twenty four female Lewis rats (180-240g) were randomly divided into 3 groups: two groups underwent TxT followed by hemorrhagic shock (35±3mmHg) for 60min and resuscitation with either Ringers-Lactat (RL) alone or RL supplemented with EP (EP, 50mg/kg). Sham operated animals underwent surgical procedures. Two hours later bronchoalveolar lavage fluid (BAL), lung tissue and blood were collected for analyses.

RESULTS

EP significantly improved pO₂ levels compared to RL after TxT+H/R. TxT+H/R induced elevated levels of lactate dehydrogenase, total protein concentration in BAL and lung damage as evidenced by lung histology; these effects were significantly reduced by EP. Local inflammatory markers, lung TNF-alpha protein levels and infiltration with polymorphonuclear leukocytes (PMNL) significantly decreased in EP vs. RL group after TxT+H/R. Indicators of apoptosis as reduced BCL-2 and increased FAS gene expression after TxT+H/R were significantly increased or decreased, respectively, by EP after TxT+H/R. EP reduced TxT+H/R-induced p65 phosphorylation, which was concomitant with reduced HMGB1 levels in lung sections.

CONCLUSIONS

Taken together, TxT+H/R induced strong inflammatory response and apoptotic changes as well as lung injury which were markedly diminished by EP. Our results suggest that this might be mediated via NF-κB and/or HMGB1 dependent mechanism.

Dietary supplementation with green tea extract promotes enhanced human leukocyte activity

BACKGROUND

Leukocytes play a vital role in the host defence and inflammatory systems, the latter being responsible for the pathogenesis of a wide spectrum of acute and chronic diseases. Green tea is a popular beverage, which is consumed worldwide and its active ingredients are epicatechin derivatives, which possess distinct anti-inflammatory properties. The purpose of this study was to investigate if a green tea extract could enhance leukocyte function in humans.

METHODS

Volunteers were asked to take 300 mg of the green tea extract daily for 14 days and the capacity of circulating leukocytes to release both myeloperoxidase and lactoferrin was assessed. Whole blood from volunteers was stimulated with the bacterial peptide Formyl-Methionine-Leucine-Phenylalanine (fMet-Leu-Phe). Myeloperoxidase an enzyme that converts hydrogen peroxide to hypochlorous acid and is stored and secreted from the granules of neutrophils and monocytes and was measured as well as lactoferrin which is an iron-binding protein stored and secreted from the neutrophils. In conjunction the antioxidant capacity of the blood of the volunteers was also determined using a chemiluminescence method that measures the capacity of plasma to scavenge superoxide.

RESULTS

After 14 days of treatment there was a significant increase in the release of myeloperoxidase and lactoferrin when whole blood was stimulated with fMet-Leu-Phe (p<0.05), which activates a number of leukocytes including mature neutrophils and monocytes. This was mirrored by a significant increase in the total antioxidant status after 14 days of green tea ingestion (p0.05). After the "wash-out" period of 4 weeks, all parameters were consistent with those observed at the start of the trial (day 0). Treatment with the green tea extract also caused a slight but non-significant decrease in the number of circulating leukocytes, but the counts remained within published "normal" ranges for healthy human adults.

CONCLUSIONS

This study indicates that a green tea extract when taken as a dietary supplement for 14 days can increase the leukocyte activity and the total plasma antioxidant status and may have role to play in the prevention of inflammatory disease.

Differential Relevance of NF-κB and JNK in the Pathophysiology of Hemorrhage/Resususcitation-Induced Liver Injury after Chronic Ethanol Feeding

BACKGROUND

Chronic ethanol (EtOH) abuse worsens pathophysiological derangements after hemorrhagic shock and resuscitation (H/R) that induce hepatic injury and strong inflammatory changes via JNK and NF-κB activation. Inhibiting JNK with a cell-penetrating, protease-resistant peptide D-JNKI-1 after H/R in mice with healthy livers ameliorated these effects. Here, we studied if JNK inhibition by D-JNKI-1 in chronically EtOH-fed mice after hemorrhagic shock prior to the onset of resuscitation also confers protection.

METHODS

Male mice were fed a Lieber-DeCarli diet containing EtOH or an isocaloric control (ctrl) diet for 4 weeks. Animals were hemorrhaged for 90 min (32 ± 2 mm Hg) and randomly received either D-JNKI-1 (11 mg/kg, intraperitoneally, i. p.) or sterile saline as vehicle (veh) immediately before the onset of resuscitation. Sham animals underwent surgical procedures without H/R and were either D-JNKI-1 or veh treated. Two hours after resuscitation, blood samples and liver tissue were harvested.

RESULTS

H/R induced hepatic injury with increased systemic interleukin (IL)-6 levels, and enhanced local gene expression of NF-κB-controlled genes such as intercellular adhesion molecule (ICAM)-1 and matrix metallopeptidase (MMP)9. c-Jun and NF-κB phosphorylation were increased after H/R. These effects were further increased in EtOH-fed mice after H/R. D-JNKI-1 application inhibited the proinflammatory changes and reduced significantly hepatic injury after H/R in ctrl-fed mice. Moreover, D-JNKI-1 reduces in ctrl-fed mice the H/R-induced c-Jun and NF-κB phosphorylation. However, in chronically EtOH-fed mice, JNK inhibition did not prevent the H/R-induced hepatic damage and proinflammatory changes nor c-Jun and NF-κB phosphorylation after H/R.

CONCLUSIONS

These results indicate, that JNK inhibition is protective only in not pre-harmed liver after H/R. In contrast, the pronounced H/R-induced liver damage in mice being chronically fed with ethanol cannot be prevented by JNK inhibition after H/R and seems to be under the control of NF-κB.

Green tea protects human osteoblasts from cigarette smoke-induced injury: possible clinical implication

PURPOSE

Recent reports discuss the altered bone homeostasis in cigarette smokers, being a risk factor for osteoporosis and negatively influencing fracture healing. Cigarette smoke is known to induce oxidative stress in the body via an increased production of reactive oxygen species (ROS). These increases in ROS are thought to damage the bone-forming osteoblasts. Naturally occurring polyphenols contained in green tea extract (GTE), e.g., catechins, are known to have anti-oxidative properties. Therefore, the aim of this study was to investigate whether GTE and especially catechins protect primary human osteoblasts from cigarette smoke-induced damage and to identify the underlying mechanisms.

METHODS

Primary human osteoblasts were isolated from patients' femur heads. Cigarette smoke medium (CSM) was obtained using a gas-washing bottle and standardized by its optical density (OD(320)) at λ = 320 nm. ROS formation was measured using 2'7'dichlorofluorescein diacetate, and osteoblasts' viability was detected by resazurin conversion.

RESULTS

Co-, pre-, and post-incubation with GTE and catechins significantly reduced ROS formation and thus improved the viability of CSM-treated osteoblasts. Besides GTE's direct radical scavenging properties, pre-incubation with both GTE and catechins protected osteoblasts from CSM-induced damage. Inhibition of the anti-oxidative enzyme HO-1 significantly reduced the protective effect of GTE and catechins emphasizing the key role of this enzyme in GTE anti-oxidative effect.

CONCLUSIONS

Our data suggest possible beneficial effects on bone homeostasis, fracture healing, and bone mineral density following a GTE-rich diet or supplementation.