Chitosan oligosaccharides downregulate the expression of E-selectin and ICAM-1 induced by LPS in endothelial cells by inhibiting MAP kinase signaling

Role of chitosan in intestinal integrity: TLR4 and IFNAR signaling in the induction of E-cadherin and CD103 in mice

Chitin and its derivative chitosan (Q) are abundant structural elements in nature. Q has modulatory and anti-inflammatory effects and also regulates the expression of adhesion molecules. The interaction between cells expressing the αEβ7 integrin and E-cadherin facilitates tolerogenic signal transmission and localization of lymphocytes at the frontline for interaction with luminal antigens. In this study we evaluated the ability of orally administered Q to stimulate E-cadherin and CD103 expression in vitro and in vivo. Our findings show that Q promoted epithelial cell migration, accelerated wound healing and increased E-cadherin expression in IEC-18 cells and isolated intestinal epithelial cells (IECs) after Q feeding. The upregulation of E-cadherin was dependent on TLR4 and IFNAR signaling, triggering CD103 expression in lymphocytes. Q reinforced the E-cadherin-αEβ7 axis, crucial for intestinal barrier integrity and contributed to the localization of lymphocytes on the epithelium.

In situ isolation of nuclei or nuclear proteins from adherent cells: a simple, effective method with less cytoplasmic contamination

BACKGROUND

Isolation of nuclei or nuclear proteins is a prerequisite for western blot, nuclear proteome profiling, and other evaluations of nuclear proteins. Here, we developed a simple method for in situ isolation of nuclei or nuclear proteins by in situ removing the extranuclear part of adherent cells via a classical nonionic detergent triton X-100.

RESULTS

First, the feasibility of our method was confirmed by confocal microscopy, atomic force microscopy, scanning electron microscopy, dynamic light scattering, immunofluorescence imaging, and time-lapse dynamic observation. Next, the optimal concentration range (approximately 0.1-1% for ~ 10 min) of triton X-100 and the optimal treatment time (< 30 min) of 0.1-1% Triton X-100 for our method were determined via western blotting of eight extra-/intra-nuclear proteins. Subsequently, the effectiveness, sensitivity, and cytoplasmic contamination of our method were tested by investigating the levels of phosphorylated p65 (a NF-κB subunit) in the nuclei of endothelial or tumor cells treated with/without lipopolysaccharide (LPS) via western blotting and by comparing with a commercial nuclear protein extraction kit (a classical detergent-based method). The data show that compared with the commercial kit our method obtained a higher yield of total nuclear proteins, a higher pP65 level in both control and LPS groups, and much lower content of GAPDH (as a reference for cytoplasmic contamination) in nuclei.

CONCLUSIONS

The in situ isolation of nuclei or nuclear proteins from adherent cells in this study is a simple, effective method with less cytoplasmic contamination. This method/strategy has the potential of improving the quality of downstream evaluations including western blotting and proteomic profiling.

Severe COVID-19-A Review of Suggested Mechanisms Based on the Role of Extracellular Matrix Stiffness

The severity of COVID-19 commonly depends on age-related tissue stiffness. The aim was to review publications that explain the effect of microenvironmental extracellular matrix stiffness on cellular processes. Platelets and endothelial cells are mechanosensitive. Increased tissue stiffness can trigger cytokine storm with the upregulated expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha and interleukin IL-6, and tissue integrity disruption, leading to enhanced virus entry and disease severity. Increased tissue stiffness in critically ill COVID-19 patients triggers platelet activation and initiates plague formation and thrombosis development. Cholesterol content in cell membrane increases with aging and further enhances tissue stiffness. Membrane cholesterol depletion decreases virus entry to host cells. Membrane cholesterol lowering drugs, such as statins or novel chitosan derivatives, have to be further developed for application in COVID-19 treatment. Statins are also known to decrease arterial stiffness mitigating cardiovascular diseases. Sulfated chitosan derivatives can be further developed for potential use in future as anticoagulants in prevention of severe COVID-19. Anti-TNF-α therapies as well as destiffening therapies have been suggested to combat severe COVID-19. The inhibition of the nuclear factor kappa-light-chain-enhancer of activated B cells pathway must be considered as a therapeutic target in the treatment of severe COVID-19 patients. The activation of mechanosensitive platelets by higher matrix stiffness increases their adhesion and the risk of thrombus formation, thus enhancing the severity of COVID-19.

Methyl-β-cyclodextrin suppresses the monocyte-endothelial adhesion triggered by lipopolysaccharide (LPS) or oxidized low-density lipoprotein (oxLDL)

CONTEXT

Recent studies demonstrated the anti-atherosclerotic efficacy of cyclodextrin. However, it remains unclear whether cyclodextrin exerts the anti-atherosclerotic effect via regulating monocyte-endothelial adhesion.

OBJECTIVE

To answer that question by recruiting methyl-β-cyclodextrin (MβCD) as a cyclodextrin representative.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were not treated, or treated with 1 µg/mL liposaccharide (LPS) or 50 µg/mL oxidized low-density lipoprotein (oxLDL) for 12 h, 5 mM MβCD for 1 h, and LPS/oxLDL (1 and 50 µg/mL, respectively for 12 h) plus MβCD (5 mM for 1 h), respectively. The effects of MβCD on LPS/oxLDL-triggered monocyte-endothelial adhesion and related molecules in signalling pathways were evaluated via confocal microscopy, flow cytometry, RT-PCR, western blotting, and cell adhesion assay.

RESULTS

MβCD with an IC₅₀ of 27.66 mM (1 h treatment) exerted no significant cytotoxicity at ≤5 mM for ≤2 h. Compared with the control, both LPS and oxLDL induced an ∼2-3-fold increase in adhesion molecule expression (ICAM-1 and VCAM-1 at protein and mRNA levels) and NF-κB phosphorylation (p-NF-κB/pP65), an increase in IκB kinase (IKK), and a decrease in phosphorylated protein kinase B (p-Akt), respectively. Moreover, more monocytes (2-fold higher for LPS and 15% higher for oxLDL) were attached on LPS/oxLDL-stimulated HUVECs. 5 mM MβCD reversed the LPS/oxLDL-induced changes back to the control levels.

CONCLUSIONS

MβCD significantly suppresses the LPS/oxLDL-triggered monocyte-endothelial adhesion by downregulating adhesion molecule expression probably via LPS-IKK-NF-κB or oxLDL-Akt-NF-κB pathway. This study demonstrates a potential mechanism of the anti-atherosclerotic efficacy of cyclodextrin from the angle of monocyte-endothelial adhesion.

Drug delivery carriers with therapeutic functions

Design of micro- or nanocarriers for drug delivery has primarily been focused on properties such as hydrophobicity, biodegradability, size, shape, surface charge, and toxicity, so that they can achieve optimal delivery with respect to drug loading, release kinetics, biodistribution, cellular uptake, and biocompatibility. Incorporation of stimulus-sensitive moieties into the carriers would lead to "smart" delivery systems. A further evolution would be to endow the carrier with a therapeutic function such that it no longer serves as a mere passive entity to release the drug at the target tissue but can be viewed as a therapeutic agent in itself. In this review, we will discuss recent and ongoing efforts over the past decade to design therapeutic drug carriers that confer a biological benefit, including ROS scavenging or generating, pro- or anti-inflammatory, and immuno-evasive properties, to enhance the overall therapeutic efficacy of the delivery systems.

The Role of Chitosan Oligosaccharide in Metabolic Syndrome: A Review of Possible Mechanisms

Metabolic syndrome, a cluster of metabolic disorders including central obesity, insulin resistance, hyperglycemia, dyslipidemia, and hypertension, has become a major public health problem worldwide. It is of great significance to develop natural products to prevent and treat metabolic syndrome. Chitosan oligosaccharide (COS) is an oligomer of chitosan prepared by the deacetylation of chitin, which is the second most abundant polymer in nature. In recent years, COS has received widespread attention due to its various biological activities. The present review will summarize the evidence from both in vitro and in vivo studies of the beneficial effects of COS on obesity, dyslipidemia, diabetes mellitus, hyperglycemia, and hypertension, and focus attention on possible mechanisms of the prevention and treatment of metabolic syndrome by COS.

The effects of the molecular weight of chitosan on the tissue inflammatory response

The molecular weight of chitosan (CS) may affect its physical properties and its ability to induce an appropriate host response. The biocompatibilities of CS membranes of low (LMWCS) and high (HMWCS) molecular weight were investigated by inserting these materials into the subcutaneous tissue of rats for 1-28 days and evaluating leukocyte infiltration, granulation tissue, fibrosis, arginase-1 immunostaining, as well as nuclear factor-κB (NF-κΒ) and fibroblast growth factor (FGF)-2 expressions. Both CS membranes induced a peak of leukocyte infiltration on the first day of insertion and stimulated granulation and fibrous tissue generation when compared to control. LMWCS induced more collagen deposition a week earlier, when compared to the control and HMWCS membrane. The membranes also increased arginase-1 immunostaining, a M2 macrophage marker. M2 macrophage is recognized as anti-inflammatory and pro-regenerative. NF-κB is an essential biomarker of the inflammatory process and induces the expression of several pro-inflammatory cytokines. The LMWCS membrane reduced inflammation, as indicated by a reduced nucleus/cytoplasm NF-κB ratio in surrounding tissue from days 7 to 14 when compared to control. On the first day, the expression of FGF-2, a biomarker of inflammatory resolution, was increased in the tissue of the LWMCS group, when compared with HMWCS, which was consistent with the type I collagen deposition. Thus, LWMCS was associated with a prior reduction of the inflammatory response and improved wound healing.

Chitin and Chitosan Derivatives as Biomaterial Resources for Biological and Biomedical Applications

Chitin is a long-chain polymer of N-acetyl-glucosamine, which is regularly found in the exoskeleton of arthropods including insects, shellfish and the cell wall of fungi. It has been known that chitin can be used for biological and biomedical applications, especially as a biomaterial for tissue repairing, encapsulating drug for drug delivery. However, chitin has been postulated as an inducer of proinflammatory cytokines and certain diseases including asthma. Likewise, chitosan, a long-chain polymer of N-acetyl-glucosamine and d-glucosamine derived from chitin deacetylation, and chitosan oligosaccharide, a short chain polymer, have been known for their potential therapeutic effects, including anti-inflammatory, antioxidant, antidiarrheal, and anti-Alzheimer effects. This review summarizes potential utilization and limitation of chitin, chitosan and chitosan oligosaccharide in a variety of diseases. Furthermore, future direction of research and development of chitin, chitosan, and chitosan oligosaccharide for biomedical applications is discussed.

Lipopolysaccharide-Induced Vascular Inflammation Model on Microfluidic Chip

Inflammation is the initiation of defense of our body against harmful stimuli. Lipopolysaccharide (LPS), originating from outer membrane of Gram-negative bacteria, causes inflammation in the animal’s body and can develop several diseases. In order to study the inflammatory response to LPS of blood vessels in vitro, 2D models have been mainly used previously. In this study, a microfluidic device was used to investigate independent inflammatory response of endothelial cells by LPS and interaction of inflamed blood vessel with monocytic THP-1 cells. Firstly, the diffusion of LPS across the collagen gel into blood vessel was simulated using COMSOL. Then, inflammatory response to LPS in engineered blood vessel was confirmed by the expression of Intercellular Adhesion Molecule 1 (ICAM-1) and VE-cadherin of blood vessel, and THP-1 cell adhesion and migration assay. Upregulation of ICAM-1 and downregulation of VE-cadherin in an LPS-treated condition was observed compared to normal condition. In the THP-1 cell adhesion and migration assay, the number of adhered and trans-endothelial migrated THP-1 cells were not different between conditions. However, migration distance of THP-1 was longer in the LPS treatment condition. In conclusion, we recapitulated the inflammatory response of blood vessels and the interaction of THP-1 cells with blood vessels due to the diffusion of LPS.

Crosstalk between chitosan and cell signaling pathways

The field of tissue engineering (TE) experiences its most exciting time in the current decade. Recent progresses in TE have made it able to translate into clinical applications. To regenerate damaged tissues, TE uses biomaterial scaffolds to prepare a suitable backbone for tissue regeneration. It is well proven that the cell-biomaterial crosstalk impacts tremendously on cell biological activities such as differentiation, proliferation, migration, and others. Clarification of exact biological effects and mechanisms of a certain material on various cell types promises to have a profound impact on clinical applications of TE. Chitosan (CS) is one of the most commonly used biomaterials with many promising characteristics such as biocompatibility, antibacterial activity, biodegradability, and others. In this review, we discuss crosstalk between CS and various cell types to provide a roadmap for more effective applications of this polymer for future uses in tissue engineering and regenerative medicine.

MicroRNAs: Novel Molecular Targets and Response Modulators of Statin Therapy

Cardiovascular disease (CVD) is a major cause of death globally. Addressing cardiovascular risk factors, particularly dyslipidemia, represents the most robust clinical strategy towards reducing the CVD burden. Statins inhibit 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase and represent the main therapeutic approach for lowering cholesterol and reducing plaque formation/rupture. The protective effects of statins extend beyond lowering cholesterol. MicroRNAs (miRNAs or miRs), small noncoding regulatory RNAs, likely mediate the positive pleiotropic effects of statins via modulation of lipid metabolism, enhancement of endothelial function, inhibition of inflammation, improvement of plaque stability, and immune regulation. miRNAs are implicated in statin-related interindividual variations in therapeutic response, directly via HMG-CoA reductase, or indirectly through targeting cytochrome P450 3A (CYP3A) functionality and proprotein convertase subtilisin/kexin type9 (PCSK9) biology.

Involvement of PKA signalling in anti-inflammatory effects of chitosan oligosaccharides in IPEC-J2 porcine epithelial cells

Weaning is characterized by intestinal inflammation, which is a big challenge in pig industry. Control of intestinal inflammation is important for improvement of growth performance and health. Therefore, the study was focused on the anti-inflammatory activity of low-molecular-weight chitosan oligosaccharide (LCOS) in a porcine small intestinal epithelial cell line (IPEC-J2). The results showed that TNF-α, as inflammation inducer, significantly upregulated the mRNA expression of IL-8 and MCP-1. Afterwards, LCOS significantly attenuated mRNA expression of IL-8 and MCP-1 induced by TNF-α in the cells. Mannose (MAN), as ligand of mannose receptor, had no effect on the anti-inflammatory activity of LCOS, which suggested that mannose receptor may not involve in the anti-inflammatory activity of LCOS in IPEC-J2 cells. Interestingly, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide 2HCl hydrate (H89), as PKA (protein kinase A)-specific inhibitor, reversed the mRNA expression of IL-8 when co-cultured with LCOS. Furthermore, LCOS concentration dependent downregulated the mRNA expression of claudin-1 compared with TNF-α treatment. However, the trans-epithelial electric resistance (TEER) was not affected by LCOS when co-cultured with TNF-α in 3 hr. In conclusion, LCOS have a potent anti-inflammatory activity, and as a feed additives, may be useful for the inhibition of inflammatory process in weaning period of pigs with intestinal inflammation occurring.

Chitosan oligosaccharide suppresses synovial inflammation via AMPK activation: An in vitro and in vivo study

Synovial inflammation plays an important role in the early pathogenesis of osteoarthritis (OA). Chitosan oligosaccharide (COS) has been shown to activate AMPK and suppress inflammatory responses in intestinal epithelial cells. This study aimed to investigate the effect of COS on AMPK activation and synovial inflammation using both primary cultures of synoviocytes and a rabbit model of anterior cruciate ligament (ACL) transection-induced OA. COS induced AMPK activation in both rabbit and human synoviocytes. The mechanism of COS-induced AMPK activation involves an increase in the ADP/ATP ratio but not calcium/calmodulin-dependent protein kinase kinase beta (CaMKKβ). Interestingly, COS suppressed the TNFα-induced iNOS and COX-2 expression via an AMPK-dependent mechanism in both rabbit and human synoviocytes. Importantly, oral administration of COS (10mg/kg/day) induced AMPK activation and alleviated signs of inflammation including COX-2 expression in the synovium of a rabbit ACL transection model. Taken together, our results indicate that COS suppresses synovial inflammation in vitro and in vivo via AMPK activation. COS may be useful in the prevention of OA.

Advances in the Study of the Antiatherogenic Function and Novel Therapies for HDL

The hypothesis that raising high-density lipoprotein cholesterol (HDL-C) levels could improve the risk for cardiovascular disease (CVD) is facing challenges. There is multitudinous clear clinical evidence that the latest failures of HDL-C-raising drugs show no clear association with risks for CVD. At the genetic level, recent research indicates that steady-state HDL-C concentrations may provide limited information regarding the potential antiatherogenic functions of HDL. It is evident that the newer strategies may replace therapeutic approaches to simply raise plasma HDL-C levels. There is an urgent need to identify an efficient biomarker that accurately predicts the increased risk of atherosclerosis (AS) in patients and that may be used for exploring newer therapeutic targets. Studies from recent decades show that the composition, structure and function of circulating HDL are closely associated with high cardiovascular risk. A vast amount of data demonstrates that the most important mechanism through which HDL antagonizes AS involves the reverse cholesterol transport (RCT) process. Clinical trials of drugs that specifically target HDL have so far proven disappointing, so it is necessary to carry out review on the HDL therapeutics.

The potential of chitosan and its derivatives in prevention and treatment of age-related diseases

Age-related, diet-related and protein conformational diseases, such as atherosclerosis, diabetes mellitus, cancer, hypercholesterolemia, cardiovascular and neurodegenerative diseases are common in the elderly population. The potential of chitosan, chitooligosaccharides and their derivatives in prevention and treatment of age-related dysfunctions is reviewed and discussed in this paper. The influence of oxidative stress, low density lipoprotein oxidation, increase of tissue stiffness, protein conformational changes, aging-associated chronic inflammation and their pathobiological significance have been considered. The chitosan-based functional food also has been reviewed.

Anticancer and anti-inflammatory properties of chitin and chitosan oligosaccharides

Previous reports indicate that N-acetyl-d-glucosamine oligomers (chitin oligosaccharide; NACOS) and d-glucosamine oligomers (chitosan oligosaccharide; COS) have various biological activities, especially against cancer and inflammation. In this review, we have summarized the findings of previous investigations that have focused on anticancer or anti-inflammatory properties of NACOS and COS. Moreover, we have introduced recent evaluation of NACOS and COS as functional foods against cancer and inflammatory disease.

Chitosan oligosaccharides attenuate ocular inflammation in rats with experimental autoimmune anterior uveitis

We investigated the protective effects and mechanisms of chitosan oligosaccharides (COS) on experimental autoimmune anterior uveitis (EAAU) in rats. EAAU was induced in Lewis rats by footpad and intraperitoneal injections of melanin-associated antigen. The rats received intraperitoneal injections of low-dose (5 mg/kg) or high-dose (10 mg/kg) COS or PBS daily after the immunization. The effects of COS were evaluated by determining the clinical scores and the morphology of the iris/ciliary body (ICB). The expression of inflammatory mediators was evaluated using western blot, immunofluorescence, and ELISA. Treatment with COS significantly attenuated the clinical scores and the leukocyte infiltration in the ICB in a dose-dependent manner. COS effectively reduced the expression of inflammatory mediators (TNF-α, iNOS, MCP-1, RANTES, fractalkine, and ICAM-1). Moreover, COS decreased the IκB degradation and p65 presence in the ICB, which resulted in the inhibition of NF-κB/DNA binding activity. In an in vitro study, sensitized spleen-derived lymphocytes of the COS-treated group showed less chemotaxis toward their aqueous humor and decreased secretion of the above inflammatory mediators in the culture media. COS treated EAAU by inhibiting the activation of NF-κB and reducing the expression of inflammatory mediators. COS might be a potential treatment for acute anterior uveitis.