Phorbol ester (PMA)-treated U937 cells cultured on type I collagen-coated dish express a lower production of pro-inflammatory cytokines through lowered ROS levels in parallel with cell aggregate formation

RhFGF21 protected PC12 cells against mitochondrial apoptosis triggered by H2O2 via the AKT-mediated ROS signaling pathway

One of the pathological mechanisms of neurodegenerative diseases is that oxidative stress damages neurons. Therefore, reducing reactive oxygen species (ROS) overload may be a promising approach for preventing and treating neurological diseases. Fibroblast growth factor 21 (FGF21) is crucial for protecting and restoring various forms of pathological injury. Consequently, the operating mechanism of FGF21 was investigated. Our research revealed that rhFGF21 could enhance the cell viability by alleviating the damage to PC12 cells after H2O2 action of via mechanisms decreasing mitochondrial apoptosis, reducing ROS production, increasing antioxidant enzyme levels, adenosine triphosphate (ATP) synthesis and mitochondrial membrane potential (MMP). Excessive ROS trigger cell apoptosis. Our findings revealed that tBHP counteracted the cell viability-boosting effect of rhFGF21 in H2O2-stimulated PC12 cells, whereas N-acetyl-L-cysteine (NAC) enhanced the viability-promoting effect of rhFGF21 in these cells. AKT is crucial in mediating ROS-induced cell apoptosis. The treatment of PC12 cells exposed to H2O2 with rhFGF21 resulted in upregulation of p-AKT expression. Moreover, rhFGF21 inhibited ROS levels and increased the cell viability, which were both reversed by administration of an AKT inhibitor (wortmannin). The research discovered that rhFGF21 mitigated mitochondrial apoptosis in PC12 cells exposed to H2O2 through the functioning of the AKT and ROS signaling axis.

Immunotoxic response of bio-based plastic on early life stage zebrafish (Danio rerio): A safe alternative to petroleum-based plastics?

Bio-based plastics are marketed as environmentally friendly alternatives to petroleum-based plastics, although they require specific composting conditions for degradation, which leads to their accumulation in the environment and potential risks to aquatic organisms. We hypothesized that the accumulation of bio-based plastics may induce immunotoxic responses in fish. Our research focused on the accumulation and immunotoxicity of 80 nm polylactic acid (PLA) and polystyrene (PS) (0.1-10 mg/L) on early life stage zebrafish (Danio rerio) exposed for 7 days. Compared to PS, there was a higher accumulation of PLA in larvae. Exposure to PLA resulted in a significant increase in neutrophils and macrophages, while immune protein levels such as Complement 3 (C3), Immunoglobulin M (IgM), and C-reactive protein (CRP) were significantly reduced. Furthermore, the mRNA expression of pro-inflammatory cytokines, including tnf-α and il-6, were significantly elevated in PLA treatments. Additionally, PLA-exposed zebrafish were more susceptible to infection by Vibrio parahaemolyticus. Interestingly, at the same concentration, exposures to PS did not induce significant changes in macrophages or immune protein levels, C3 and IgM. This suggests that PLA has a greater immunotoxic response relative to PS. Our research findings contradict the popular belief that bio-based plastics are non-toxic and harmless, which may have potential risk to aquatic organisms.

Responsive Multi-Arm PEG-Modified COF Nanocomposites: Dynamic Photothermal, pH/ROS Dual-Responsive, Targeted Carriers for Rheumatoid Arthritis Treatment

Rheumatoid arthritis (RA) is a chronic immune disease characterized by the infiltration of immune cells and the proliferation of fibroblast-like synoviocytes (FLS) at the joint site, leading to inflammation and joint destruction. However, the available treatment options targeting both inflammatory and proliferative FLS are limited. Herein, this work presents three covalent organic frameworks (COFs) photothermal composite systems modified with multi-armed polyethylene glycols (PEG) for the treatment of RA. These systems exhibit a dual response under low pH and high reactive oxygen species (ROS) conditions at the site of inflammation, with a specific focus on delivering the protein drug ribonuclease A (RNase A). Notably, molecular docking studies reveal the interaction between RNase A and NF-κB p65 protein, and Western blotting confirm its inhibitory effect on NF-κB activity. In vitro and in vivo experiments verify the significant reduction in joint swelling and deformities in adjuvant-induced arthritis (AIA) rats after treatment with RNase A delivered by multi-armed PEG-modified COF ligands, restoring joint morphology to normal. These findings underscore the promising therapeutic potential of COFs for the treatment of RA, highlighting their unique capabilities in addressing both inflammatory and proliferative aspects of the disease and expanding the scope of biomedical applications for COFs.

Gelatin but not type I collagen promotes bacteria phagocytosis in PMA-treated U937 human lymphoma cells

PURPOSE

Besides comprising scaffolding, extracellular matrix components modulate many biological processes including inflammation and cell differentiation. We previously found precoating cell plates with extracellular matrix collagen I, or its denatured product gelatin, causes aggregation of macrophage-like human lymphoma U937 cells, which are induced to differentiation by phorbol myristate treatment. In the present study, we investigated the influence of gelatin or collagen I precoating on the bacteria phagocytosis in PMA-stimulated U937 cells.

MATERIALS AND METHODS

Colony forming units of phagocytosed bacteria, Giemsa-staining of cells with phagocytosed bacteria, confocal microscopic and flow cytometric analysis of cells with phagocytosed FITC-labeled bacteria and non-bioactive latex beats were conducted.

RESULTS

Gelatin precoating enhances the phagocytosis of both Gram-negative and positive bacteria, as shown by the increased colony forming units of bacteria phagocytosed by cells, and increased intracellular bacteria observed after Giemsa-staining. But collagen I has no marked influence. Confocal microscopy reveals that both live and dead FITC-bacteria were phagocytosed more in the cells with gelatin-coating but not collagen-coating. Of note, both gelatin and collagen I coating had no influence on the phagocytosis of non-bioactive latex beads. Since gelatin-coating increases autophagy but collagen I has no such impact, we are curious about the role of autophagy. Inhibiting autophagy reduced the phagocytosis of bacteria, in cells with gelatin-coating, while stimulating autophagy enhanced phagocytosis.

CONCLUSION

This study finds the bacteria-phagocytosis stimulatory effect of gelatin in PMA-treated U937 cells and reveals the positive regulatory role of autophagy, predicting the potential use of gelatin products in anti-bacterial therapy.

The collagen matrix regulates the survival and function of pancreatic islets

The extracellular matrix (ECM) provides an appropriate microenvironment for many kinds of cells, including pancreatic cells. Collagens are the most abundant components of the ECM. Type I, IV, V and VI collagen has been detected in pancreatic islets, and each type plays important role in the proliferation, survival, function and differentiation of pancreatic cells. In some cases, collagens show behaviours similar to those of growth factors and regulate the biological behaviour of β cells by binding with certain growth factors, including IGFs, EGFs and FGFs. The transcriptional coactivator YAP/TAZ has been widely recognised as a mechanosensor that senses changes in the physical characteristics of the ECM and inhibition of YAP/TAZ enhances insulin production and secretion. Type 1 diabetes mellitus (T1DM) is an autoimmune disease characterised by the destruction of insulin-producing β cells. The crosstalk between collagens and immune cells plays a key role in the development and differentiation of immune cells. Further, Supplementation with collagens during islet transplantation is a promising strategy for improving the quality of the islets. But, excessive collagen deposition results in pancreatic fibrosis and pancreatic carcinoma. Targeting inhibit Piezo, autophagy or IL-6 may reduce excessive collagen deposition-induced pancreatic fibrosis and pancreatic carcinoma. This review provides insights into the treatment of T1DM to prolong life expectancy and provides the potential targets for treating collagen deposition-induced pancreatic fibrosis and pancreatic carcinoma.

Type I collagen reduces lipid accumulation during adipogenesis of preadipocytes 3T3-L1 via the YAP-mTOR-autophagy axis

The extracellular matrix (ECM) regulates cell behavior through signal transduction and provides a suitable place for cell survival. As one of the major components of the extracellular matrix, type I collagen is involved in regulating cell migration, proliferation and differentiation. We present a system in which 3T3-L1 preadipocyte cells are induced for adipogenic differentiation on type I collagen coated dishes. Our previous study has found that type I collagen inhibits adipogenic differentiation via YAP activation. Here we further reveal that type I collagen inactivates autophagy by up-regulating mTOR activity via the YAP pathway. Under collagen-coating conditions, co-localization of lysosomes with mTOR was increased and the level of downstream protein p-S6K was elevated, accompanied by a decrease in the level of autophagy. Autophagy is negatively correlated with adipogenesis under type I collagen coating. Through the YAP-autophagy axis, type I collagen improves glycolipid metabolism accompanied by increased mitochondrial content, enhanced glucose uptake, reduced release of free fatty acids (FFAs) and decreased intracellular lipid accumulation. Our findings provide insight into the strategy for dealing with obesity: Type I collagen or the drugs with inhibitory effects on autophagy or YAP, have a potential to accelerate the energy metabolism of adipose tissue, so as to better maintain the homeostasis of glucose and lipids in the body, which can be used for achieving weight loss.

Immune Modulatory Properties of Collagen in Cancer

During tumor growth the extracellular matrix (ECM) undergoes dramatic remodeling. The normal ECM is degraded and substituted with a tumor-specific ECM, which is often of higher collagen density and increased stiffness. The structure and collagen density of the tumor-specific ECM has been associated with poor prognosis in several types of cancer. However, the reason for this association is still largely unknown. Collagen can promote cancer cell growth and migration, but recent studies have shown that collagens can also affect the function and phenotype of various types of tumor-infiltrating immune cells such as tumor-associated macrophages (TAMs) and T cells. This suggests that tumor-associated collagen could have important immune modulatory functions within the tumor microenvironment, affecting cancer progression as well as the efficacy of cancer immunotherapy. The effects of tumor-associated collagen on immune cells could help explain why a high collagen density in tumors is often correlated with a poor prognosis. Knowledge about immune modulatory functions of collagen could potentially identify targets for improving current cancer therapies or for development of new treatments. In this review, the current knowledge about the ability of collagen to influence T cell activity will be summarized. This includes direct interactions with T cells as well as induction of immune suppressive activity in other immune cells such as macrophages. Additionally, the potential effects of collagen on the efficacy of cancer immunotherapy will be discussed.

A Bottom-Up Approach Grafts Collagen Fibrils Perpendicularly to Titanium Surfaces

Currently, titanium dental implant apposition to bone is achieved via osseointegration leading to ankylosis. A biomimetic Sharpey's fiber-type interface could be constructed around collagen fibrils robustly attached and projecting perpendicularly from the titanium surface. We present a proof-of-concept for a method to create upright-standing collagen nanofibrils covalently bonded to a titanium surface. The method involves activation of the titanium surface using a plasma discharge treatment followed by functionalization with an oxyamine-terminated silane coupling molecule. Using Rapoport's salt, the N-termini of individual type I collagen monomers are converted to ketones. When presented to the functionalized titanium surface, these ketones form oxime linkages with the silanes thus immobilizing the collagen. In a two-step process, these covalently bonded monomers act as sites for the formation of fibrils. Many fibril-surface junctions were observed by scanning electron microscopy on three different surfaces. These findings set the stage for working toward a high surface density of such features which might act as a platform from which to build a synthetic ligament.

Induction of tryptophan 2,3-dioxygenase expression in human monocytic leukemia/lymphoma cell lines THP-1 and U937

Tumor-associated macrophages are immune cells with diverse functions in tumor development. Among other functions, they downregulate immune-mediated tumor rejection by depriving lymphocytes of nutrients. The essential amino acid tryptophan is metabolized by the enzymes indoleamine 2,3-dioxygenase 1 and tryptophan 2,3-dioxygenase (TDO). Indoleamine 2,3-dioxygenase 1 is expressed in a large number of human tumors, and inhibitors are in development to improve immunotherapy. Tryptophan 2,3-dioxygenase was also found in human tumors and preclinical working models confirmed its immunosuppressive power. We explored a potential expression of TDO by macrophages. This enzyme could be induced in two human cell lines, THP-1 and U937, by incubation with phorbol myristate acetate, lipopolysaccharide, and interferon gamma. Phorbol-myristate-acetate-mediated induction was inhibited by rottlerin, a protein kinase C inhibitor. In contrast to these monocytic cell lines, other cell lines or fresh human monocytes isolated from peripheral blood mononuclear cells and differentiated into proinflammatory or anti-inflammatory macrophages could not be induced to express TDO. Our results suggest that TDO might play an immunosuppressive role in human monocytic leukemias but not in untransformed macrophages.

Type I collagen or gelatin stimulates mouse peritoneal macrophages to aggregate and produce pro-inflammatory molecules through upregulated ROS levels

BACKGROUND

Extracellular matrix (ECM) comprising the environments of multicellular society has a dynamic network structure. Collagen is one of the ubiquitous components of ECM. Collagen affects the inflammatory response by regulating the release of pro-inflammatory cytokines from cells. Gelatin, denatured collagen found temporally in tissues, is supposed to be pathophysiologically involved in tissue remodeling, inflammation caused by tissue damage. Previous reports indicate that, phorbol myristate (PMA)-stimulated human U937 (lymphoma cell line) cells that are often used as macrophage-like cells, show cell aggregations when cultured on type I collagen (col I) or gelatin-coated dishes, accompanying the changes of production and release of proinflammatory factors. However, it still remains to be examined whether collagen and gelatin affects normal macrophages as well.

AIM

This study aims to investigate the effect of col. I, the main component of collagenous protein and its denatured product, gelatin, on mouse peritoneal macrophages (MPMs).

METHODS

MTT assay, flow cytometric analysis of ROS, biochemical detection of antioxidant levels, ELISA assay, and western blot were used.

RESULTS

MPMs formed multicellular aggregates on col. I - and gelatin-coated dishes with a concentration- and time-dependent manner. Further studies showed that the culture on col. I and gelatin up-regulated the protein expression and secretion of pro-inflammatory molecules such as IL-1β, TNFα and prostaglandin E₂ (PGE₂) in MPMs. The levels were higher in the cells on gelatin than those on col. I. ROS levels are significantly increased in the cells cultured on both col. I- and gelatin-coated dishes, accompanying decreased levels of antioxidant enzyme catalase (CAT) and anti-oxidant glutathione (GSH), and enhanced nuclear translocation of NF-κB.

CONCLUSION

Col I - or gelatin-coated culture induced the formation of multicellular aggregates and increased production of NF-κB-associated pro-inflammatory molecules in MPMs through up-regulation of ROS levels.

Reactive oxygen species are responsible for the cell aggregation and production of pro-inflammatory mediators in phorbol ester (PMA)-treated U937 cells on gelatin-coated dishes through upregulation of autophagy

Purpose: Our previous studies indicate that phorbol 12-myristate 13-acetate (PMA)-treated U937 cells cultured on collagen I-coated dishes express lowered production of pro-inflammatory mediators in parallel through reduced reactive oxygen species (ROS) levels. By contrast, PMA-treated U937 cells on gelatin, the denatured collagen, show enhanced production of pro-inflammatory mediators, mediated by up-regulating autophagy levels. The present study is aimed to investigate the effect of ROS levels in PMA-treated U937 cells cultured on gelatin-coated surface. Material and methods: MTT assay, flow cytometric analysis of ROS and autophagy, biochemical detection of antioxidant levels, enzyme-linked immunosorbent assay, and western blot were used. Results: Gelatin-coating increased ROS levels in PMA-treated U937 cells. Increased ROS levels are involved in the regulation of cell aggregation and the release of pro-inflammatory mediators in gelatin-coated culture. These results lead to the query about the crosstalk between the two positive regulators, the autophagy and ROS. Autophagy induction is attenuated by N-acetyl-L-cysteine treatment, but the treatment with autophagy inhibitor, 3-methyladenine, does not affect ROS levels, suggesting ROS are upstream of autophagy in the regulation axis of differentiated U937 cells on gelatin-coated surface. Further study confirmed that upregulation of autophagy was responsible for ROS-induced cell aggregation and production of pro-inflammatory mediators. Conclusion: The results suggest that gelatin-coating promotes the aggregation of PMA-treated U937 cells and the production of pro-inflammatory mediators by ROS-autophagy signaling pathway.