Tannic acid protects against experimental acute lung injury through downregulation of TLR4 and MAPK

Cell-homing and immunomodulatory composite hydrogels for effective wound healing with neovascularization

Wound healing in cases of excessive inflammation poses a significant challenge due to compromised neovascularization. Here, we propose a multi-functional composite hydrogel engineered to overcome such conditions through recruitment and activation of macrophages with adapted degradation of the hydrogel. The composite hydrogel (G-TSrP) is created by combining gelatin methacryloyl (GelMA) and nanoparticles (TSrP) composed of tannic acid (TA) and Sr2+. These nanoparticles are prepared using a one-step mineralization process assisted by metal-phenolic network formation. G-TSrP exhibits the ability to eliminate reactive oxygen species and direct polarization of macrophages toward M2 phenotype. It has been observed that the liberation of TA and Sr2+ from G-TSrP actively facilitate the recruitment and up-regulation of the expression of extracellular matrix remodeling genes of macrophages, and thereby, coordinate in vivo adapted degradation of the G-TSrP. Most significantly, G-TSrP accelerates angiogenesis despite the TA's inhibitory properties, which are counteracted by the released Sr2+. Moreover, G-TSrP enhances wound closure under inflammation and promotes normal tissue formation with strong vessel growth. Genetic analysis confirms macrophage-mediated wound healing by the composite hydrogel. Collectively, these findings pave the way for the development of biomaterials that promote wound healing by creating regenerative environment.

Activation of ERK/NF-kB Pathways Contributes to the Inflammatory Response in Epithelial Cells and Macrophages Following Manganese Exposure

Different types of metals, including manganese (Mn), are constantly encountered in various environmental matrices due to natural and anthropogenic activities. They induce a sustained inflammatory response in various organs, which is considered to be an important priming event in the pathogenesis of several diseases. Mn-induced neuroinflammation and subsequent neurodegeneration are well recognized. However, emerging data suggest that occupationally and environmentally relevant levels may affect various organs, including the lungs. Therefore, the present study was carried out to investigate the effects of Mn (as Mn2+) exposure on the inflammatory response in human normal bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells, as well as in murine macrophages (J774). Mn2+ exposure significantly induced mRNA and protein expression of various pro-inflammatory mediators (cytokines and chemokines) in all cells compared to corresponding vehicle controls. Furthermore, Mn2+ treatment also led to increased phosphorylation of extracellular-signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-kB) p65 in both epithelial cells and macrophages. As expected, cells treated with inhibitors of ERK1/2 (PD98059) and NF-kB p65 (IMD0354) effectively mitigated the expression of various pro-inflammatory mediators induced by Mn2+, suggesting that ERK/NF-kB pathways have a critical role in the Mn2+-induced inflammatory response. Further, in vivo studies are required to confirm these in vitro findings to support clinical translation.

Cellulose nanofibers embedded chitosan/tannin hydrogel with high antibacterial activity and hemostatic ability for drug-resistant bacterial infected wound healing

Millions of patients annually suffer life-threatening illnesses caused by bacterial infections of skin wounds. However, the treatment of wounds infected with bacteria is a thorny issue in clinical medicine, especially with drug-resistant bacteria infections. Therefore, there is an increasing interest in developing wound dressings that can efficiently fight against drug-resistant bacterial infections and promote wound healing. In this work, an anti-drug-resistant bacterial chitosan/cellulose nanofiber/tannic acid (CS/CNF/TA) hydrogel with excellent wound management ability was developed by electrospinning and fiber breakage-recombination. The hydrogel exhibited an outstanding antibacterial property exceeding 99.9 %, even for drug-resistant bacteria. This hydrogel could adhere to the tissue surface due to its abundant catechol groups, which avoided the shedding of hydrogel during the movement. Besides, it exhibited extraordinary hemostatic ability during the bleeding phase of the wound and then regulated the wound microenvironment by absorbing water and moisturizing. Moreover, the CS/CNF/TA also promoted the regrowth of vessels and follicles, accelerating the healing of infected wound tissue, with a healing rate exceeding 95 % within a 14-day timeframe. Therefore, the CS/CNF/TA hydrogel opens a new approach for the healing of drug-resistant bacterial infected wounds.

Dietary tannic acid attenuates elastase-induced pulmonary inflammation and emphysema in mice

Emphysema is one of the major components of chronic obstructive pulmonary disease (COPD), which is characterised by the destruction and enlargement of air spaces, leading to airflow limitation and dyspnoea, finally progressing to oxygen dependency. The alveolar wall destruction is due to chronic inflammation, oxidative stress, apoptosis, and proteinase/anti-proteinase imbalance. So far, there has been no effective therapy for patients with COPD. We evaluated the therapeutic efficacy of tannic acid (TA), a naturally occurring plant-derived polyphenol in the murine emphysema model. In C57BL/6 J mice, we established emphysema by intratracheal instillation of elastase (EL). Then, mice were treated with TA and evaluated 1 and 21 days post-EL instillation. After 24 h, TA treatment significantly reduced EL-induced histopathological alterations, infiltrating leukocytes, and gene expression of markers of inflammation and apoptosis. Similarly, after 21 days, TA treatment suppressed the mean linear intercept, gene expression of proteinases, and increased elastic fiber contents in the lungs when compared to the EL-alone group. Furthermore, EL induced the activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa light chain enhancer of activated B cells (NF-kB) p65 pathways in the lungs was suppressed by TA treatment. In summary, TA has the potential to mitigate EL-induced inflammation, apoptosis, proteinase/anti-proteinase imbalance, and subsequent emphysema in mice.

Circ-phkb promotes cell apoptosis and inflammation in LPS-induced alveolar macrophages via the TLR4/MyD88/NF-kB/CCL2 axis

BACKGROUND

Circular RNAs (CircRNAs) have been associated with acute lung injury (ALI), but their molecular mechanisms remain unclear.

METHODS

This study developed a rat model of lipopolysaccharide (LPS)-induced ALI and evaluated the modeling effect by hematoxylin and eosin staining, Masson's trichrome staining, lung wet-to-dry weight ratio, terminal deoxynucleotidyl transferase UTP nick end labeling (TUNEL), and enzyme-linked immunosorbent assay (ELISA) detection of inflammatory factors (interleukin-1β, tumor necrosis factor alpha, and interleukin-6). Using lung tissues from a rat model of LPS-induced ALI, we then conducted circRNA sequencing, mRNA sequencing, and bioinformatics analysis to obtain differential circRNA and mRNA expression profiles as well as potential ceRNA networks. Furthermore, we performed quantitative real-time polymerase chain reaction (qRT-PCR) assays to screen for circ-Phkb in ALI rat lung tissues, alveolar macrophages, and LPS-induced NR8383 cells. We conducted induction with or without LPS with circ-Phkb siRNA and overexpression lentivirus in NR8383. Cell Counting Kit-8, C5-Ethynyl-2'-deoxyuridine (Edu), TUNEL, and cytometry were used to identify proliferation and apoptosis, respectively. We detected inflammatory factors using ELISA. Finally, we used Western blot to detect the apoptosis-related proteins and TLR4/MyD88/NF-kB/CCL2 pathway activation.

RESULTS

Our results revealed that both circRNA and mRNA profiles are different from those of the Sham group. We observed a significant circ-Phkb upregulation in NR8383 cells and LPS-exposed rats. Apoptosis and inflammation were greatly reduced when circ-Phkb expression was reduced in NR8383 cells, cell proliferation was increased, and circ-Phkb overexpression was decreased.

CONCLUSIONS

In terms of mechanism, circ-Phkb suppression inhibits CCL2 expression via the TLR4/MyD88/NF-kB pathway in LPS-induced alveolar macrophages.

Analysis of abnormal expression of signaling pathways in PQ-induced acute lung injury in SD rats based on RNA-seq technology

Background: Paraquat (PQ) plays an important role in agricultural production due to its highly effective herbicidal effect. However, it has led to multiple organ failure in those who have been poisoned, with damage most notable in the lungs and ultimately leading to death. Because of little research has been performed at the genetic level, and therefore, the specific genetic changes caused by PQ exposure are unclear.Methods: Paraquat poisoning model was constructed in Sprague Dawley (SD) rats, and SD rats were randomly divided into Control group, paraquat (PQ) poisoning group and Anthrahydroquinone-2,6-disulfonate (AH2QDS) treatment group. Then, the data was screened and quality controlled, compared with reference genes, optimized gene structure, enriched at the gene expression level, and finally, signal pathways with significantly different gene enrichment were screened.Results: This review reports on lung tissues from paraquat-intoxicated Sprague Dawley (SD) rats that were subjected to RNA-seq, the differentially expressed genes were mainly enriched in PI3K-AKT, cGMP-PKG, MAPK, Focal adhesion and other signaling pathways.Conclusion: The signaling pathways enriched with these differentially expressed genes are summarized, and the important mechanisms mediated through these pathways in acute lung injury during paraquat poisoning are outlined to identify important targets for AH2QDS treatment of acute lung injury due to paraquat exposure, information that will be used to support a subsequent in-depth study on the mechanism of PQ action.

MicroRNA-195-5p mediates arsenic-induced cytotoxicity in human lung epithelial cells: Beneficial role of plant-derived tannic acid

Arsenic (As), a highly toxic metalloid, which causes environmental lung diseases and affects millions of people worldwide. Respiratory epithelial cells are essential for maintaining lung homeostasis, aberrant epithelial damage and death due to exposure to a wide range of environmental pollutants, which are considered to be the initial trigger for many pulmonary diseases. Accumulating evidence has shown that microRNAs (miRNAs) appear to be important players in various normal physiological and pathological processes. Therefore, the present study was carried out to examine the cytotoxic effects of a trivalent form of As (As3+) in normal human bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells and the role of miR-195-5p. Further, we also explored the protective effects of a natural dietary polyphenol tannic acid (TA). As3+ (1 μM) treatment in BEAS-2B cells for 24 h induced cytotoxicity by decreasing the cell viability, mitochondrial membrane potential (ΔΨm) and inducing reactive oxygen species (ROS) generation, lipid peroxidation (LPO), cell cycle arrest, and apoptosis, which was associated with a significantly higher level of miR-195-5p expression compared with vehicle control. Forced expression of miR-195-5p alone suppressed cell survival, ΔΨm, regulated cell cycle distribution and induced ROS generation in BEAS-2B cells. As expected, miR-195-5p inhibition effectively rescued BEAS-2B cells from As3+-mediated toxicity, confirming the involvement of miR-195-5p in the cytotoxic effects of As3+. Further, TA pre-treatment expressively alleviated As3+-induced toxicity by suppressing ROS production, miR-195-5p expression, and increasing ΔΨm. These in vitro results indicate that miR-195-5p may be useful as a therapeutic target for treating As3+ toxicity.

Effects of hydrolyzed gallotannin on intestinal physical barrier, immune function, and microbiota structure of yellow-feather broilers

The present study was performed to explore the effects of dietary supplementation of hydrolyzed gallotannin (HGT) on intestinal physical barrier, immune function and microbiota structure in yellow-feather broilers. A total of 288 male yellow-feather broilers were randomly allocated to 4 diet treatments: the basal diet (CON) and 3 diets supplemented with 150, 300, and 450 mg/kg HGT for 63 d, respectively, with 6 replicates per treatment and 12 birds per replicate. The findings demonstrated that 300 or 450 mg/kg HGT addition enhanced the expression of duodenal occludin (OCLN) and tight junction protein1 (TJP-1) genes of birds at 21 d of age, and the expression of duodenal and ileal OCLN gene in 63-day-old broilers was upregulated due to 450 mg/kg HGT treatment (P < 0.05). The dietary supplementation of 150 mg/kg HGT strengthened the expression of duodenal IL-6 and IL-4 genes and ileal IL-4 gene of 21-day-old broilers, whereas the expression of jejunal IL1B and IL-6 genes in birds at 63 d of age weakened because of 300 or 450 mg/kg HGT addition (P < 0.05). As for microbial community, the HGT addition altered the cecal microbiota structure of birds at 21 d of age based on analysis of similarities (ANOSIM) test and 450 mg/kg HGT treatment increased the relative abundance of norank Eubacterium coprostanoligenes group at 21 d of age and unclassified Lachnospiraceae at 63 d of age (P < 0.05). In short, diet supplemented with 300 to 450 mg/kg HGT may be the optimal for yellow-feather broilers to enhance intestinal barrier function. Altogether, our study clarified the regulatory role of HGT in broiler intestinal health in earnest, but the underlying mechanism is still unclear. Hence, more research is needed to carry out until the application of HGT as a new functional additive in broiler production.

Himalayan flora: targeting various molecular pathways in lung cancer

The fatal amplification of lung cancer across the globe and the limitations of current treatment strategies emphasize the necessity for substitute therapeutics. The incorporation of phyto-derived components in chemo treatment holds promise in addressing those challenges. Despite the significant progressions in lung cancer therapeutics, the complexities of molecular mechanism and pathways underlying this disease remain inadequately understood, necessitating novel biomarker targeting. The Himalayas, abundant in diverse plant varieties with established chemotherapeutic potential, presents a promising avenue for investigating potential cures for lung carcinoma. The vast diversity of phytocompounds herein can be explored for targeting the disease. This review delves into the multifaceted targets of lung cancer and explores the established phytochemicals with their specific molecular targets. It emphasizes comprehending the intricate pathways that govern effective therapeutic interventions for lung cancer. Through this exploration of Himalayan flora, this review seeks to illuminate potential breakthroughs in lung cancer management using natural compounds. The amalgamation of Himalayan plant-derived compounds with cautiously designed combined therapeutic approaches such as nanocarrier-mediated drug delivery and synergistic therapy offers an opportunity to redefine the boundaries of lung cancer treatment by reducing the drug resistance and side effects and enabling an effective targeted delivery of drugs. Furthermore, additional studies are obligatory to understand the possible derivation of natural compounds used in current lung cancer treatment from plant species within the Himalayan region.

Hydrolysable tannins as a potential therapeutic drug for the human fibrosis-associated disease

Fibrosis is a pathological change with abnormal tissue regeneration due to a response to persistent injury, which is extensively related to organ damage and failure, leading to high morbidity and mortality worldwide. Although the pathogenesis of fibrosis has been comprehensively elucidated, there are few effective therapies for treating fibrotic diseases. Natural products are increasingly regarded as an effective strategy for fibrosis with numerous favorable functions. Hydrolysable tannins (HT) are a type of natural products that have the potential to treat the fibrotic disease. In this review, we describe some biological activities and the therapeutic prospects of HT in organ fibrosis. Furthermore, the underlying mechanisms of inhibition of HT on fibrotic organs in relation to inflammation, oxidative stress, epithelial-mesenchymal transition, fibroblast activation and proliferation, and extracellular matrix accumulation are discussed. Understanding the mechanism of HT against fibrotic diseases will provide a new strategy for the prevention and attenuation of fibrosis progression.

ITGB4 deficiency in airway epithelia enhances HDM-induced airway inflammation through hyperactivation of TLR4 signaling pathway

Airway epithelial cells (AECs) are the first cell barrier of the respiratory system against external stimuli that play a critical role in the development of asthma. It is known that AECs play a key role in asthma susceptibility and severity. ITGB4 is a downregulated adhesion molecule in the airway epithelia of asthma patients, which was involved in the exaggerated lung inflammation after allergy stimulation. Toll-like receptor 4 (TLR4) in AECs has also been shown to play a crucial role in the development of lung inflammation in asthma patients. However, the specific intrinsic regulatory mechanism of TLR4 in AECs are still obscure. In this article, we demonstrated that ITGB4 deficiency in AECs enhances HDM-induced airway inflammation through hyperactivation of the TLR4 signaling pathway, which is mediated by inhibition of FYN phosphorylation. Moreover, TLR4-antagonist treatment or blockade of FYN can inhibit or exaggerate lung inflammation in HDM-stressed ITGB4-deficient mice, separately. Together, these results demonstrated that ITGB4 deficiency in AECs enhances HDM-induced lung inflammatory response through the ITGB4-FYN-TLR4 axis, which may provide new therapeutic approaches for the management of lung inflammation in asthma.

Dietary Galla Chinensis tannic acid supplementation in the diets improves growth performance, immune function and liver health status of broiler chicken

This experiment was conducted to investigate the effects of Galla Chinensis tannic acid (TA) on growth performance, immune function, and liver health status in broilers. A total of 288 1-day-old Arbor Acres broiler chickens were randomly divided into two groups in a 42-days study. The two groups were a basal diet (CON group) and a basal diet supplemented with 300 mg/kg Galla Chinensis tannic acid (TA group). The results showed that the TA group had significantly decreased feed-to-gain ratio (F/G) throughout the experiment (P < 0.05). The levels of total protein, albumin, low density lipoprotein, high density lipoprotein, urea, total cholesterol, and glucose in the TA group were significantly higher than in the CON group (P < 0.05). In addition, the serum immunoglobulin G, immunoglobulin M, and complements (C3, C4) levels in the TA group were significantly higher than those in the CON group (P < 0.05). Compared with the CON group, the hepatic interleukin-6, interleukin-18, NLRs family pyrin domain containing 3 (NLRP3), caspase-1, and caspase-3 in the TA group were significantly decreased (P < 0.05). Besides, TA group had significantly lower mRNA expression levels of toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), nuclear factor-kappa B (NF-κB), and NLRP3 in liver (P < 0.05). The TA group had significantly higher the mRNA expression levels of Bcl-2 than CON group in liver (P < 0.05). Moreover, TA group tended to decrease Bax/Bcl-2 ratio in liver (P < 0.10). To sum up, dietary supplemented with microencapsulated TA from Galla Chinensis had beneficial effects on growth performance, immune function, and liver health status in broilers. The protective role of TA from Galla Chinensis in liver health of broilers might be related to the inhibition of hepatic apoptosis and pyroptosis via inactivation of TLR4/MyD88/NF-κB signaling pathway.

Biomimetic anti-inflammatory and osteogenic nanoparticles self-assembled with mineral ions and tannic acid for tissue engineering

Bone healing involves complex processes including inflammation, induction, and remodeling. In this context, anti-inflammatory and osteoconductive multi-functional nanoparticles have attracted considerable attention for application in improved bone tissue regeneration. In particular, nanoparticles that promote suppression of inflammatory response after injury and direction of desirable tissue regeneration events are of immense interest to researchers. We herein report a one-step method to prepare multi-functional nanoparticles using tannic acid (TA) and simulated body fluid (SBF) containing multiple mineral ions. Mineral-tannic acid nanoparticles (mTNs) were rapidly fabricated in 10 min, and their size (around 250-350 nm) and chemical composition were controlled through the TA concentration. In vitro analysis using human adipose derived stem cells (hADSCs) showed that mTNs effectively scavenged reactive oxygen species (ROS) and enhanced osteogenesis of hADSCs by inducing secretion of alkaline phosphatase. mTNs also increased osteogenic marker gene expression even in the presence of ROS, which can generally arrest osteogenesis (OPN: 1.74, RUNX2: 1.90, OCN: 1.47-fold changes relative to cells not treated with mTNs). In vivo analysis using a mouse peritonitis model revealed that mTNs showed anti-inflammatory effects by decreasing levels of pro-inflammatory cytokines in blood (IL-6: 73 ± 4, TNF-α: 42 ± 2%) and peritoneal fluid (IL-6: 78 ± 2, TNF-α: 21 ± 6%). We believe that this one-step method for fabrication of multi-functional nanoparticles has considerable potential in tissue engineering approaches that require control of complex microenvironments, as required for tissue regeneration.

Classic Signaling Pathways in Alveolar Injury and Repair Involved in Sepsis-Induced ALI/ARDS: New Research Progress and Prospect

Sepsis is a common critical clinical disease with high mortality that can cause approximately 10 million deaths worldwide each year. Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is a common clinical complication of sepsis, which occurs primarily as diffuse alveolar injury, hypoxemia, and respiratory distress. The mortality rate of ALI/ARDS is as high as 30%-40%, which greatly endangers human health. Due to the unclear pathogenesis of ALI/ARDS, its treatment is still a worldwide problem. At present, clinical treatment mainly relies on lung-protective ventilation, prone position ventilation, and fluid management. However, there is a lack of effective and specific treatment measures. In recent years, domestic and foreign scholars have committed to basic research on ALI/ARDS, trying to further clarify its pathogenesis and find new targets and methods for the treatment of ALI/ARDS. In this review, we summarize the signaling pathways related to alveolar injury and repair in sepsis-induced ALI/ARDS and their latest research progress. They include the NF-κB, JAK2/STAT3, mitogen-activated protein kinase (MAPK), mTOR, and Notch signaling pathways. Understanding the molecular mechanisms of these signaling pathways in sepsis-induced ALI/ARDS may provide new targets and ideas for the clinical treatment of this disease.

Vincamine, an active constituent of Vinca rosea ameliorates experimentally induced acute lung injury in Swiss albino mice through modulation of Nrf-2/NF-κB signaling cascade

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is one of the leading pulmonary inflammatory disorders causing significant morbidity and mortality. Vincamine is a novel phytochemical with promising anti-inflammatory properties. In the current work, the protective effect of vincamine was studied in vitro (Raw 264.7 macrophages) and in vivo against lipopolysaccharide (LPS) induced ALI in Swiss albino mice. Vincamine significantly reduced nitrite and TNF-α release from the LPS stimulated macrophages and increased the levels of IL-10, indicating potent anti-inflammatory effects. It was observed that vincamine at the dose of 40 mg/kg, significantly reduced LPS induced inflammatory cell count in blood and in bronchoalveolar lavage (BAL) fluid. Further, vincamine exerted potent suppression of inflammation by reducing the expression of proinflammatory cytokines, while significantly increased (p < 0.001) the expression of anti-inflammatory cytokine (IL-10 and IL-22). Interestingly, histological changes were reversed in vincamine treated groups in a dose-dependent manner. Immunohistochemical analysis revealed significantly enhanced expression of NF-κB, TNF-α and COX-2 while reduced expression of Nrf-2 in disease control group, which were significantly (p < 0.001) ameliorated by vincamine. We, to the best of our knowledge, report for the first time that vincamine possesses protective potential against LPS induced inflammation and oxidative stress, possibly by inhibiting the NF-κB cascade, while positively regulating the Nrf-2 pathway. These findings are of potential relevance for COVID-19 management concerning the fact that lung injury and ARDS are its critical features.

Post‑treatment with propofol inhibits inflammatory response in LPS‑induced alveolar type II epithelial cells

Over-inflammation and severe lung injury are major causes of morbidity and mortality in patients with coronavirus disease 2019 (COVID-19). With the COVID-19 pandemic, an increasing number of patients with preexisting lung injury and inflammation are undergoing surgery or artificial ventilation under sedation in intensive care units, where 2,6-diisopropylphenol (propofol) is a commonly used drug for sedation. The aim of the present study was to investigate whether post-inflammation treatment with propofol protects epithelial type II cells against inflammation in an in vitro model of inflammation. The A549 cell line, characterised as epithelial type II cells, were exposed to lipopolysaccharide (LPS) for 2 h and subsequently treated with different concentrations of propofol (0, 10, 25 or 50 µM) for 3 h. Western blot and reverse transcription-quantitative PCR analyses were used to detect the protein and mRNA expression levels, respectively, of CD14 and Toll-like receptor 4 (TLR4). Immunofluorescence staining was used to detect the in situ CD14 and TLR4 expression in epithelial type II cells. Tumor necrosis factor (TNF)-α production was also examined using ELISA. LPS significantly increased the expression of CD14 and TLR4, as well as the secretion of TNF-α. Post-treatment with 25 and 50 µM propofol of the LPS-treated cells significantly decreased CD14 and TLR4 expression, as well as TNF-α secretion, compared with the cells treated with LPS only, indicating that post-treatment with propofol alleviated inflammation and this effect was dose-dependent. The present study suggested that treatment with propofol after LPS administration has a protective effect on epithelial type II cells.

New Properties and Mitochondrial Targets of Polyphenol Agrimoniin as a Natural Anticancer and Preventive Agent

Agrimoniin is a polyphenol from the group of tannins with antioxidant and anticancer activities. It is assumed that the anticancer action of agrimoniin is associated with the activation of mitochondria-dependent apoptosis, but its mitochondrial targets have not been estimated. We examined the direct influence of agrimoniin on different mitochondrial functions, including the induction of the mitochondrial permeability transition pore (MPTP) as the primary mechanism of mitochondria-dependent apoptosis. Agrimoniin was isolated from Agrimonia pilosa Ledeb by multistep purification. The content of agrimoniin in the resulting substance reached 80%, as determined by NMR spectroscopy. The cytotoxic effect of purified agrimoniin was confirmed on the cultures of K562 and HeLa cancer cells by the MTT assay. When tested on isolated rat liver mitochondria, agrimoniin at a low concentration (10 µM) induced the low-amplitude swelling, which was inhibited by the MPTP inhibitors ADP and cyclosporine A, activated the opening of MPTP by calcium ions and stimulated the respiration supported by succinate oxidation. Also, agrimoniin reduced the electron acceptor DCPIP in a concentration-dependent manner and chelated iron ions. Owing to all these properties, agrimoniin can stimulate apoptosis or activate mitochondrial functions, which can be helpful in the prevention and elimination of stagnant pathological states.

Glutamine Supplementation Attenuates the Inflammation Caused by LPS-Induced Acute Lung Injury in Mice by Regulating the TLR4/MAPK Signaling Pathway

Bacterial infection is one of the main causes of bovine respiratory disease (BRD), which can cause tremendous losses for the herd farming industry worldwide. L-Glutamine (GLN), a neutral amino acid, has been reported to have anti-inflammatory properties. This study aims to explore the potential protective effects and mechanisms of GLN on acute lung injury (ALI) induced by lipopolysaccharide (LPS) in mice. Forty ICR mice were randomly divided into four groups (n = 10): a PBS intratracheal instillation group, a LPS intratracheal instillation group, a GLN gavage group, and a LPS+GLN group (GLN was given 1 h before the LPS stimulation). Twelve hours after LPS administration, the lung tissue and blood were collected. The results showed that the concentrations of IL-6, IL-8, and IL-1β; the protein abundance of the toll-like receptor 4 (TLR4), phosphorylated p38 (p-p38), phosphorylated ERK1/2 (p-ERK1/2), and phosphorylated JNK (p-JNK); and the expression level of genes associated with inflammation, such as IL-1β, IL-8, TNF-α, IL-6, TLR4, p38, ERK1/2, and JNK, were significantly increased in the LPS group compared with those in the PBS group. However, these increases were attenuated by GLN pretreatment in the LPS+GLN group. Furthermore, the pathological change of the structure of lung tissue from the LPS group was obvious compared to that from the PBS group; however, with GLN administration, these pathological changes were alleviated. Additionally, the secretion level of mucus and the percentage of positive MUC5AC staining on the epithelial surface area of the airway increased dramatically in the LPS group; however, GLN pretreatment in the LPS+GLN group markedly decreased these phenomena compared with that of the LPS group. These results indicate that GLN supplementation ameliorates LPS-induced ALI in mice and this effect may be mediated by the TLR4/MAPK signaling pathway.

Assessing the mechanisms of action of natural molecules/extracts for phase-directed wound healing in hydrogel scaffolds

Hydrogels are proving to be very versatile as wound healing devices. In addition to their capabilities of providing a moist cellular environment and adaptive mechanical properties mimicking the extracellular matrix, they allow the incorporation of small molecules, which have potential impacts on cellular behaviour, in their nanostructures. This strategy can allow for specific targeting of the different stages of wound healing namely hemostasis, inflammation, and proliferative and remodelling phases. The latter include interlinked processes such as angiogenesis, collagen synthesis, growth factor release, collagen maturation and re-epithelialization. In this review, we attempt to match the mechanisms of action of natural molecules/extracts to the different stages of wound healing so that they can be used in a novel approach of multiphase-directed tissue regeneration using loaded hydrogel scaffolds.

An overview on the role of plant-derived tannins for the treatment of lung cancer

Lung cancer is the leading cause of cancer-related death globally. Despite many advanced approaches to treat cancer, they are often ineffective due to resistance to classical anti-cancer drugs and distant metastases. Currently, alternative medicinal agents derived from plants are the major interest due to high bioavailability and fewer adverse effects. Tannins are polyphenolic compounds existing as specialized products in a wide variety of vegetables, fruits, and nuts. Many tannins have been found to possess protective properties, such as anti-inflammatory, anti-fibrotic, anti-microbial, anti-diabetic, and so on. This review aims to summarize the current knowledge addressing the anti-cancer effects of dietary tannins and their underlying molecular mechanisms. In vivo and in vitro studies provide evidences that anti-cancer effects of various tannins are predominantly mediated through negative regulation of transcription factors, growth factors, receptor kinases, and many oncogenic molecules. In addition, we also discussed the absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of tannins, clinical trial results as well as our perspective on future research with tannins.

Anti-asthmatic effects of tannic acid from Chinese natural gall nuts in a mouse model of allergic asthma

Asthma is a chronic inflammatory disease of the airways, which is characterized by infiltration of inflammatory cells, airway hyperresponsiveness (AHR), and airway remodeling. This study aimed to explore the role and mechanism of tannic acid (TA), a naturally occurring plant-derived polyphenol, in murine asthma model. BALB/c mice were given ovalbumin (OVA) to establish an allergic asthma model. The results revealed that TA treatment significantly decreased OVA-induced AHR, inflammatory cells infiltration, and the expression of various inflammatory mediators (Th2 and Th1 cytokines, eotaxin, and total IgE). Additionally, TA treatment also attenuated increases in mucins (Muc5ac and Muc5b) expression, mucus production in airway goblet cells, mast cells infiltration, and airway remodeling induced by OVA exposure. Furthermore, OVA-induced NF-κB (nuclear factor- kappa B) activation and cell adhesion molecules expression in the lungs was suppressed by TA treatment. In conclusion, TA effectively attenuated AHR, inflammatory response, and airway remodeling in OVA-challenged asthmatic mice. Therefore, TA may be a potential therapeutic option against allergic asthma in clinical settings.

Tannic acid alleviates lipopolysaccharide‑induced H9C2 cell apoptosis by suppressing reactive oxygen species‑mediated endoplasmic reticulum stress

Sepsis-induced myocardial dysfunction is one of the features of multiple organ dysfunction in sepsis, which is associated with extremely high mortality and is characterized by impaired myocardial compliance. To date, there are few effective treatment options available to cure sepsis. Tannic acid (TA) is reportedly protective during sepsis; however, the underlying mechanisms by which TA protects against septic heart injury remain elusive. The present study investigated the potential effects and underlying mechanisms of TA in alleviating lipopolysaccharide (LPS)-induced H9C2 cardiomyocyte cell apoptosis. H9C2 cells were treated with LPS (15 µg/ml), TA (10 µM) and TA + LPS; control cells were treated with medium only. Apoptosis was measured using flow cytometry, reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis. Additionally, the levels of cellular reactive oxygen species (ROS), malondialdehyde and nicotinamide adenine dinucleotide phosphate were evaluated. Western blotting and RT-qPCR were also employed to detect the expression levels of endoplasmic reticulum (ER) stress-associated functional proteins. The present findings demonstrated that TA reduced the degree of LPS-induced H9C2 cell injury, including inhibition of ROS production and ER stress (ERS)-associated apoptosis. ERS-associated functional proteins, including activating transcription factor 6, protein kinase-like ER kinase, inositol-requiring enzyme 1, spliced X box-binding protein 1 and C/EBP-homologous protein were suppressed in response to TA treatment. Furthermore, the expression levels of ERS-associated apoptotic proteins, including c-Jun N-terminal kinase, Bax, cytochrome c, caspase-3, caspase-12 and caspase-9 were reduced following treatment with TA. Additionally, the protective effects of TA on LPS-induced H9C2 cells were partially inhibited following treatment with the ROS inhibitor N-acetylcysteine, which demonstrated that ROS mediated ERS-associated apoptosis and TA was able to decrease ROS-mediated ERS-associated apoptosis. Collectively, the present findings demonstrated that the protective effects of TA against LPS-induced H9C2 cell apoptosis may be associated with the amelioration of ROS-mediated ERS. These findings may assist the development of potential novel therapeutic methods to inhibit the progression of myocardial cell injury.

Therapeutic potential of plant-derived tannins in non-malignant respiratory diseases

Respiratory diseases are the major cause of human illness and death around the world. Despite advances in detection and treatment, very few classes of safe and effective therapy have been introduced to date. At present, phytochemicals are getting more attention because of their diverse beneficial activities and minimal toxicity. Tannins are polyphenolic secondary metabolites with high molecular weights, which are naturally present in a wide variety of fruits, vegetables, cereals, and leguminous seeds. Many tannins are endowed with well-recognized protective properties, such as anti-cancer, anti-microbial, anti-oxidant, anti-hyperglycemic, and many others. This review summarizes a large body of experimental evidence implicating that tannins are helpful in tackling a wide range of non-malignant respiratory diseases including acute lung injury (ALI), pulmonary fibrosis, asthma, pulmonary hypertension, and chronic obstructive pulmonary disease (COPD). Mechanistic pathways by which various classes of tannins execute their beneficial effects are discussed. In addition, clinical trials and our perspective on future research with tannins are also reviewed.

Cross-linked acellular lung for application in tissue engineering: Effects on biocompatibility, mechanical properties and immunological responses

The concept of providing tissue engineering scaffolds with natural physical properties and minimal immunogenicity has not been systematically approached for the lungs yet. Here, the rat acellular lung tissue (ALT) was cross-linked to provide either EDC/NHS cross-linked tissue (EDC/NHS-CLT) or tannic acid cross-linked tissue (TA-CLT). Young's modulus revealed that EDC/NHS-CLT had mechanical properties similar to the native lung and culture of lung mesenchymal cells showed a higher potential of cell proliferation on EDC/NHS-CLT versus TA-CLT and ALT. The in vitro immunogenicity tests showed a strong induction of T-cell proliferation by TA-CLT and an attenuated macrophage induction by TA-CLT. Processed rat lungs were implanted xenogenically into the mouse peritoneal cavity and the host-implant interactions showed that tannic acid is not released from TA-CLT in a physiologically effective dose. The profile of peritoneal fluid proinflammatory (TNFα, IL-1β, IL-12p70 and IL-17) and anti-inflammatory (IL-10 and TGFβ1) cytokines, and CD3⁺ T-lymphocytes and CD11b⁺ macrophages revealed that apart from induction of high levels of IL-17 during the first week and IL-10 during the second to third weeks after implantation by TA-CLT, other indicators of immune reactions to cross-linked tissues were not significantly different from ALT. Also, a high fibrotic reaction to TA-CLT was observed on the weeks 2-3, but alveolar structures were preserved in EDC/NHS-CLT. Our findings show that by controlled EDC/NHS cross-linking, an acellular lung scaffold could be provided with mechanical properties similar to native lung, which promotes mesenchymal lung cells proliferation and does not stimulate recipient's immune system more than a non-cross-linked tissue.

Natural product derived phytochemicals in managing acute lung injury by multiple mechanisms

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) as common life-threatening lung diseases with high mortality rates are mostly associated with acute and severe inflammation in lungs. With increasing in-depth studies of ALI/ARDS, significant breakthroughs have been made, however, there are still no effective pharmacological therapies for treatment of ALI/ARDS. Especially, the novel coronavirus pneumonia (COVID-19) is ravaging the globe, and causes severe respiratory distress syndrome. Therefore, developing new drugs for therapy of ALI/ARDS is in great demand, which might also be helpful for treatment of COVID-19. Natural compounds have always inspired drug development, and numerous natural products have shown potential therapeutic effects on ALI/ARDS. Therefore, this review focuses on the potential therapeutic effects of natural compounds on ALI and the underlying mechanisms. Overall, the review discusses 159 compounds and summarizes more than 400 references to present the protective effects of natural compounds against ALI and the underlying mechanism.

Negative Effects of SIGIRR on TRAF6 Ubiquitination in Acute Lung Injury In Vitro

In this study, the effects of single immunoglobin IL-1 receptor-related protein (SIGIRR) on tumor necrosis factor- (TNF-) receptor-associated factor 6 (TRAF6) ubiquitination in acute lung injury (ALI) were evaluated in both alveolar epithelial cells and alveolar macrophage cells in vitro. Our results found that SIGIRR negatively regulated TRAF6 ubiquitination and such SIGIRR inhibition could enhance the TRAF6 expression in both alveolar epithelial cells (AECs) and alveolar macrophage cells (AMCs). SIGIRR knockdown may increase NF-κB activity via TRAF6 regulation by the classical but not the nonclassical NF-κB signaling pathway. Such modulation between TRAF6 and SIGIRR could affect cytokine secretion and exacerbate the immune response; the IL-8, NFKB1, and NFKBIA mRNA levels were reduced after SIGIRR overexpression. The current study reveals the molecular mechanisms of the negative regulatory roles of SIGIRR on the innate immune response related to the LPS/TLR-4 signaling pathway and provides evidence for strategies to clinically treat inflammatory diseases.

Is Toll-like receptor 4 involved in the severity of COVID-19 pathology in patients with cardiometabolic comorbidities?

The severe form of COVID-19 is marked by an abnormal and exacerbated immunological host response favoring to a poor outcome in a significant number of patients, especially those with obesity, diabetes, hypertension, and atherosclerosis. The chronic inflammatory process found in these cardiometabolic comorbidities is marked by the overexpression of pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumoral necrosis factor-alpha (TNF-α), which are products of the Toll-Like receptors 4 (TLR4) pathway. The SARS-CoV-2 initially infects cells in the upper respiratory tract and, in some patients, spread very quickly, needing respiratory support and systemically, causing collateral damage in tissues. We hypothesize that this happens because the SARS-CoV-2 spike protein interacts strongly with TLR4, causing an intensely exacerbated immune response in the host's lungs, culminating with the cytokine storm, accumulating secretions and hindering blood oxygenation, along with the immune system attacks the body, leading to multiple organ failure.

Punicalagin ameliorates wear-particle-induced inflammatory bone destruction by bi-directional regulation of osteoblastic formation and osteoclastic resorption

Periprosthetic osteolysis (PPO) and subsequent aseptic loosening are the main causes of implant failure and revision surgery. Emerging evidence has suggested that wear-particle-induced chronic inflammation, osteoblast inhibition and osteoclast formation at the biointerface of implant materials are responsible for PPO. Punicalagin (PCG), a polyphenolic compound molecularly extracted from pomegranate rinds, plays a critical role in antioxidant, anticancer and anti-inflammatory activities. However, whether PCG could attenuate chronic inflammation and bone destruction at sites of titanium (Ti)-particle-induced osteolysis remains to be determined. In this study, we explored the effect of PCG on Ti-particle-induced osteolysis in vivo and osteoblast and osteoclast differentiation in vitro. We found that PCG could relieve wear-particle-induced bone destruction in a murine calvarial osteolysis model by increasing bone formation activity and suppressing bone resorption activity. PCG treatment also reduced the Ti-particle-induced inflammatory response in vivo and vitro. In addition, we also observed that PCG promotes osteogenic differentiation of MC3T3-E1 cells under inflammatory conditions and inhibits RANKL-induced osteoclast formation of bone marrow-derived macrophages (BMMs). Meanwhile, the induction of the RANKL to OPG ratio was reversed by PCG treatment in vivo and in vitro, which demonstrated that PCG could also indirectly inhibit osteoclastogenesis. Collectively, our findings suggest that PCG represents a potential approach for the treatment of wear-particle-induced inflammatory osteolysis.

MiR-122-5p protects against acute lung injury via regulation of DUSP4/ERK signaling in pulmonary microvascular endothelial cells

AIMS

The aim of this study was to explore the role of miR-122-5p in acute lung injury.

MATERIALS AND METHODS

Mice were subjected to intratracheal injection of lipopolysaccharide to establish an acute lung injury model. The mice also received miR-122-5p antagonist and mimic via injection to inhibit or overexpress miR-122-5p in the lung tissue, respectively. In an in vitro experiment, we isolated primary mouse lung microvascular endothelial cells and established a cell injury model via lipopolysaccharide treatment.

KEY FINDINGS

Mice injected with an miR-122-5p antagonist exhibited reduced lung injury, inflammation and oxidative stress, while mice injected with a miR-122-5p mimic exhibited exaggerated lung injury, inflammation and oxidative stress. In an in vitro experiment, we found that the miR-122-5p antagonist suppressed lipopolysaccharide-induced inflammation, apoptosis and oxidative stress. Moreover, miR-122-5p regulated the promoter activity of DUSP4, which negatively regulated ERK1/2 signaling. The use of DUSP4 siRNA counteracted the effects of the miR-122-5p antagonist.

SIGNIFICANCE

Taken together, these results show that miR-122-5p protected against acute lung injury via regulation of DUSP4/ERK signaling in pulmonary microvascular endothelial cells. MiR-122-5p antagonism may be a promising treatment method for acute lung injury.

Tannic acid alleviates experimental pulmonary fibrosis in mice by inhibiting inflammatory response and fibrotic process

Pulmonary fibrosis (PF) is a chronic and irreversible scarring disease in the lung with limited treatment options. Therefore, it is critical to identify new therapeutic options. This study was undertaken to identify the effects of tannic acid (TA), a naturally occurring dietary polyphenol, in a mouse model of PF. Bleomycin (BLM) was intratracheally administered to induce PF. Administration of TA significantly reduced BLM-induced histological alterations, inflammatory cell infiltration and the levels of various inflammatory mediators (nitric oxide, leukotriene B₄ and cytokines). Additionally, treatment with TA also impaired BLM-mediated increases in pro-fibrotic (transforming growth factor-β1) and fibrotic markers (alpha-smooth muscle actin, vimentin, collagen 1 alpha and fibronectin) expression. Further investigation indicated that BLM-induced phosphorylation of Erk1/2 (extracellular signal-regulated kinases 1 and 2) in lungs was suppressed by TA treatment. Findings of this study suggest that TA has the potential to mitigate PF through inhibiting the inflammatory response and fibrotic process in lungs and that TA might be useful for the treatment of PF in clinical practice.

4-hydroxybenzo[d]oxazol-2(3H)-one ameliorates LPS/D-GalN-induced acute liver injury by inhibiting TLR4/NF-κB and MAPK signaling pathways in mice

The purpose of this study was to synthesize 4-hydroxybenzo[d]oxazol-2(3H)-one (HBO) and to investigate its protective effects on lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute liver injury. HBO (C₇H₅O₃N) was synthesized based on 2-nitro-resorcinol and identified by physicochemical analysis. In the animal experiment, mice were pretreated with HBO (50, 100, 200 mg/kg) for 10 days. At the end of pretreatment, the animals were injected with LPS (10 µg/kg)/D-GalN (700 mg/kg). The results showed that HBO significantly alleviated liver injury induced by LPS/D-GalN in mice. It remarkably decreased inflammatory response by reducing the levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). Moreover, HBO notably attenuated hepatocyte apoptosis by inhibiting the release of Cytochrome C (Cyt C) from mitochondria into the cytoplasm and regulating the expression of B-cell lymphoma-2 (Bcl-2) family. Furthermore, the result showed that HBO inhibited the expressions of nuclear factor kappa-B p50 (NF-κBp50), toll-like receptor 4 (TLR4), and myeloid differentiation factor 88 (MyD88), as well as the phosphorylation of inhibitor of nuclear factor kappa-B (IκB), inhibitor of nuclear factor kappa-B kinase-α/β (IKK-α/β), nuclear factor kappa-B p65 (NF-κBp65), suggesting that HBO had a certain influence on the TLR4/NF-κB pathway. In addition, the mitogen-activated protein kinase (MAPK) signaling pathway was also affected by HBO, as evidenced by the decrease in the phosphorylation levels of extracellular regulated protein kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38). In conclusion, our study suggested that HBO could protect against LPS/D-GalN-induced liver injury, moreover, treatment with HBO appeared to be capable of further regulating the TLR4/NF-κB and MAPK signaling pathways.

Oxidative Stress Mechanisms in the Pathogenesis of Environmental Lung Diseases

Globally, respiratory diseases are major cause of disability and mortality, and more alarmingly, it disproportionately affects developing countries, which is largely attributed to poor quality of air. Tobacco smoke and emissions from combustion of fossil fuel and biomass fuel are the major airborne pollutants affecting human lung health. Oxidative stress is the dominant driving force by which the airborne pollutants exert their toxicity in lungs and cause respiratory diseases. Most airborne pollutants are associated with intrinsic oxidative potential and, additionally, stimulate endogenous production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Elevated ROS and RNS in lungs modulate redox signals and cause irreversible damage to critical biomolecules (lipids, proteins and DNA) and initiate various pathogenic cellular process. This chapter provides an insight into oxidative stress-linked pathogenic cellular process such as lipid peroxidation, inflammation, cell death, mitochondrial dysfunction, endoplasmic reticulum stress, epigenetic changes, profibrotic signals and mucus hypersecretion, which drive the development and progression of lung diseases. Lungs are associated with robust enzymatic and non-enzymatic (GSH, ascorbic acid, uric acid, vitamin E) antioxidant defences. However, sustained production of free radicals due to continuous exposures to airborne pollutants overwhelms lung antioxidant defences and causes oxidative injury. Preclinical studies have demonstrated the critical roles and therapeutic potential of upregulating lung antioxidants for intervention of respiratory diseases; however, so far clinical benefits in antioxidant supplementation trials have been minimal and conflicting. Antioxidants alone may not be effective in treatment of respiratory diseases; however it could be a promising adjunctive therapy.

Protective effect of miR-20a against hypoxia/reoxygenation treatment on cardiomyocytes cell viability and cell apoptosis by targeting TLR4 and inhibiting p38 MAPK/JNK signaling

MicroRNAs (miRNAs) are recognized to hold essential parts in the course of pathophysiology participating in myocardial ischemia/reperfusion (I/R) injury. The current study was intended to appraise the functional implication and underlying regulatory mechanism action of miR-20a in myocardial I/R injury. In cardiomyocyte hypoxia/reoxygenation (H/R) model simulating I/R, we observed that miR-20a was diminished in H9c2 cells subjected to H/R. The miR-20a mimics promoted cardiomyocyte viability and reduced H/R-triggered cell apoptosis, while the miR-20a inhibitors induced the inverse response in H9c2 cells subjected to H/R injury. Moreover, we ascertained that TLR4 was one downstream target gene of miR-20a and revealed that miR-20a might hold its protective action on cardiomyocytes subjected to H/R by inactivating p38 MAPK/JNK signaling. In summary, this study highlighted the relieved potential of miR-20a against cardiomyocyte H/R injury and suggested its favorable therapeutic role for myocardial I/R injury.