Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and an irreversible lung disorder characterized by the accumulation of fibroblasts and myofibroblasts in the extracellular matrix. The transforming growth factor-β1 (TGF-β1)-induced epithelial-to-mesenchymal transition (EMT) is thought to be one of the possible sources for a substantial increase in the number of fibroblasts/myofibroblasts in IPF lungs. Tannic acid (TA), a natural dietary polyphenolic compound has been shown to possess diverse pharmacological effects. However, whether TA can inhibit TGF-β1-mediated EMT in lung epithelial cells remains enigmatic. Both the human adenocarcinomic alveolar epithelial (A549) and normal bronchial epithelial (BEAS-2B) cells were treated with TGF-β1 with or without TA. Results showed that TA addition, markedly inhibited TGF-β1-induced EMT as assessed by reduced expression of N-cadherin, type-1-collagen, fibronectin, and vimentin. Furthermore, TA inhibited TGF-β1-induced cell proliferation through inducing cell cycle arrest at G0/G1 phase. TGF-β1-induced increase in the phosphorylation of Smad (Smad2 and 3), Akt as well as that of mitogen activated protein kinase (ERK1/2, JNK1/2, and p38) mediators was effectively inhibited by TA. On the other hand, TA reduced the TGF-β1-induced increase in TGF-β receptors expression. Using molecular docking approach, FTIR, HPLC and Western blot analyses, we further identified the direct binding of TA to TGF-β1. Finally, we conclude that TA might directly interact with TGF-β1, thereby repressing TGF-β signaling and subsequent EMT process in lung epithelial cells. Further animal studies are needed to clarify its potential therapeutic benefit in pulmonary fibrosis.

Extracellular vesicles (EVs) are small biological particles released into biofluids by every cell. Based on their size, they are classified into small EVs (<100 nm or <200 nm) and medium or large EVs (>200 nm). In recent years, EVs have garnered interest for their potential medical applications, including disease diagnosis, cell-based biotherapies, targeted drug delivery systems, and others. Currently, the long-term and short-term storage temperatures for biofluids and EVs are −80 °C and 4 °C, respectively. The storage capacity of EVs can depend on their number, size, function, temperature, duration, and freeze–thaw cycles. While these parameters are increasingly studied, the effects of preservation and storage conditions of EVs on their integrity remain to be understood. Knowledge gaps in these areas may ultimately impede the widespread applicability of EVs. Therefore, this review summarizes the current knowledge on the effect of storage conditions on EVs and their stability and critically explores prospective ways for improving long-term storage conditions to ensure EV stability.

The overall data suggested that C-PC suppresses TGF- β1-induced EMT and warrants further in vivo studies for future evaluation of C-PC as a potential antifibrotic agent.

No abstract

Acute lung injury (ALI) and its severe form acute respiratory distress syndrome (ARDS) remain a major cause of morbidity and mortality in critically ill patients, and no specific therapies are still available to control the mortality rate. Thus, we explored the preventive and therapeutic effects of tannic acid (TA), a natural polyphenol in the context of ALI. We used in vivo and in vitro models, respectively, using lipopolysaccharide (LPS) to induce ALI in mice and exposing J774 and BEAS-2B cells to LPS. In both preventive and therapeutic approaches, TA attenuated LPS-induced histopathological alterations, lipid peroxidation, lung permeability, infiltration of inflammatory cells, and the expression of proinflammatory mediators. In addition, invitro study showed that TA treatment could reduce the expression of proinflammatory mediators. Further studies revealed that TA-dampened inflammatory responses by downregulating the LPS-induced toll-like receptor 4 (TLR4) expression and inhibiting extracellular-signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (MAPK) activation. Furthermore, cells treated with the inhibitors of ERK1/2 (PD98059) and p38 (SB203580) mitigated the expression of cytokines induced by LPS, thus suggesting that ERK1/2 and p38 activity are required for the inflammatory response. In conclusion, TA could attenuate LPS-induced inflammation and may be a potential therapeutic agent for ALI-associated inflammation in clinical settings. K E Y W O R D SALI, cytokines, LPS, MAPK, tannic acid, TLR4

No abstract

No abstract

Emerging evidence suggests that Gram-negative bacteria release bacterial outer membrane vesicles (OMVs) and that these play an important role in the pathogenesis of bacterial infection-mediated inflammatory responses and organ damage. Despite the fact that scattered reports have shown that OMVs released from Gram-negative bacteria may function via the TLR2/4-signaling pathway or induce pyroptosis in macrophages, our study reveals a more complex role of OMVs in the development of inflammatory lung responses and macrophage pro-inflammatory activation. We first confirmed that various types of Gram-negative bacteria release similar OMVs which prompt pro-inflammatory activation in both bone marrow-derived macrophages and lung alveolar macrophages. We further demonstrated that mice treated with OMVs via intratracheal instillation developed significant inflammatory lung responses. Using mouse inflammation and autoimmune arrays, we identified multiple altered cytokine/chemokines in both bone marrow-derived macrophages and alveolar macrophages, suggesting that OMVs have a broader spectrum of function compared to LPS. Using TLR4 knock-out cells, we found that OMVs exert more robust effects on activating macrophages compared to LPS. We next examined multiple signaling pathways, including not only cell surface antigens, but also intracellular receptors. Our results confirmed that bacterial OMVs trigger both surface protein-mediated signaling and intracellular signaling pathways, such as the S100-A8 protein-mediated pathway. In summary, our studies confirm that bacterial OMVs strongly induced macrophage pro-inflammatory activation and inflammatory lung responses via multi-signaling pathways. Bacterial OMVs should be viewed as a repertoire of pathogen-associated molecular patterns (PAMPs), exerting more robust effects than Gram-negative bacteria-derived LPS.