Dexmedetomidine facilitates autophagic flux to promote liver regeneration by suppressing GSK3β activity in mouse partial hepatectomy

INTRODUCTION

Dexmedetomidine (DEX), a highly selective α2-adrenergic receptor agonist, is widely used for sedation and anesthesia in patients undergoing hepatectomy. However, the effect of DEX on autophagic flux and liver regeneration remains unclear.

OBJECTIVES

This study aimed to determine the role of DEX in hepatocyte autophagic flux and liver regeneration after PHx.

METHODS

In mice, DEX was intraperitoneally injected 5 min before and 6 h after PHx. In vitro, DEX was co-incubated with culture medium for 24 h. Autophagic flux was detected by LC3-II and SQSTM1 expression levels in primary mouse hepatocytes and the proportion of red puncta in AML-12 cells transfected with FUGW-PK-hLC3 plasmid. Liver regeneration was assessed by cyclinD1 expression, Edu incorporation, H&E staining, ki67 immunostaining and liver/body ratios. Bafilomycin A1, si-GSK3β and Flag-tagged GSK3β, α2-ADR antagonist, GSK3β inhibitor, AKT inhibitor were used to identify the role of GSK3β in DEX-mediated autophagic flux and hepatocyte proliferation.

RESULTS

Pre- and post-operative DEX treatment promoted liver regeneration after PHx, showing 12 h earlier than in DEX-untreated mice, accompanied by facilitated autophagic flux, which was completely abolished by bafilomycin A1 or α2-ADR antagonist. The suppression of GSK3β activity by SB216763 and si-GSK3β enhanced the effect of DEX on autophagic flux and liver regeneration, which was abolished by AKT inhibitor.

CONCLUSION

Pre- and post-operative administration of DEX facilitates autophagic flux, leading to enhanced liver regeneration after partial hepatectomy through suppression of GSK3β activity in an α2-ADR-dependent manner.

Novel Biocatalysts Based on Bromelain Immobilized on Functionalized Chitosans and Research on Their Structural Features

Enzyme immobilization on various carriers represents an effective approach to improve their stability, reusability, and even change their catalytic properties. Here, we show the mechanism of interaction of cysteine protease bromelain with the water-soluble derivatives of chitosan-carboxymethylchitosan, N-(2-hydroxypropyl)-3-trimethylammonium chitosan, chitosan sulfate, and chitosan acetate-during immobilization and characterize the structural features and catalytic properties of obtained complexes. Chitosan sulfate and carboxymethylchitosan form the highest number of hydrogen bonds with bromelain in comparison with chitosan acetate and N-(2-hydroxypropyl)-3-trimethylammonium chitosan, leading to a higher yield of protein immobilization on chitosan sulfate and carboxymethylchitosan (up to 58 and 65%, respectively). In addition, all derivatives of chitosan studied in this work form hydrogen bonds with His158 located in the active site of bromelain (except N-(2-hydroxypropyl)-3-trimethylammonium chitosan), apparently explaining a significant decrease in the activity of biocatalysts. The N-(2-hydroxypropyl)-3-trimethylammonium chitosan displays only physical interactions with His158, thus possibly modulating the structure of the bromelain active site and leading to the hyperactivation of the enzyme, up to 208% of the total activity and 158% of the specific activity. The FTIR analysis revealed that interaction between N-(2-hydroxypropyl)-3-trimethylammonium chitosan and bromelain did not significantly change the enzyme structure. Perhaps this is due to the slowing down of aggregation and the autolysis processes during the complex formation of bromelain with a carrier, with a minimal modification of enzyme structure and its active site orientation.

Microbial polysaccharides: An emerging family of natural biomaterials for cancer therapy and diagnostics

Microbial polysaccharides (MPs) offer immense diversity in structural and functional properties. They are extensively used in advance biomedical science owing to their superior biodegradability, hemocompatibility, and capability to imitate the natural extracellular matrix microenvironment. Ease in tailoring, inherent bio-activity, distinct mucoadhesiveness, ability to absorb hydrophobic drugs, and plentiful availability of MPs make them prolific green biomaterials to overcome the significant constraints of cancer chemotherapeutics. Many studies have demonstrated their application to obstruct tumor development and extend survival through immune activation, apoptosis induction, and cell cycle arrest by MPs. Synoptic investigations of MPs are compulsory to decode applied basics in recent inclinations towards cancer regimens. The current review focuses on the anticancer properties of commercially available and newly explored MPs, and outlines their direct and indirect mode of action. The review also highlights cutting-edge MPs-based drug delivery systems to augment the specificity and efficiency of available chemotherapeutics, as well as their emerging role in theranostics.

Cinnamaldehyde-modified chitosan hybrid nanoparticles for DOX delivering to produce synergistic anti-tumor effects

Cancer cells are under oxidative stress associated with the increased generation of reactive oxygen species (ROS). Therefore, increasing the oxidative stress of tumor cells by delivering ROS generators is an effective strategy to induce apoptosis of cancer cells. Herein, we reported a hybrid nanoparticle based on lactobionic acid (LA) modified chitosan and cinnamaldehyde (CA) modified chitosan, which possesses both active tumor-targeting ability and ROS regulation ability, in order to have a synergistic effect with the anti-tumor drug doxorubicin (DOX). LA can improve the tumor-targeting ability and cellular accumulation of these nanoparticles, and CA can induce apoptotic cell death through ROS generation, mitochondrial permeability transition and caspase activation. The particle size and distribution as well as drug release profiles of these nanoparticles were observed. In vitro and in vivo antitumor studies demonstrated that the hybrid nanoparticles show a significant synergistic antitumor effect. Thus, we anticipate that the hybrid nanoparticles have promising potential as an anticancer drug carrier.

Multi-strategic approaches for enhancing active transportation using self-emulsifying drug delivery system

Oral delivery is the most desired route of drug administration and it can be more beneficial for patients suffering from chronic diseases wherein frequent parenteral administration of proteins such as insulin and calcitonin is required. The BCS class II drugs show low aqueous solubility and high permeability whereas BCS class IV drugs suffer from low aqueous solubility and low permeability. Additionally, biologic drugs are highly sensitive to presence of bioenzymes and bile salts when administered orally. Self-emulsifying drug delivery system (SEDDS) is a thermodynamically stable lipid formulation that enhances oral absorption of active ingredients via the opening of tight junctions, increasing the membrane fluidity, and thus overcomes the physiological barriers like viscous mucus layer, strong acid conditions and enzymatic degradation. An understanding of different theories that govern SEDDS formation and drug release can help in formulating a highly stable and effective drug delivery system. Poorly permeable drugs such as chlorpromazine require modification using methods like hydrophobic ion pairing, complexation with phospholipids, etc. to enable high entrapment efficiency which is discussed in the article. Additionally, the article gives an overview of the influence of polymers, length of fatty acids chain and zeta potential in enhancing permeation across the intestinal membrane.

Proposed hypothesis of GSK-3 β inhibition for stimulating Wnt/β-catenin signaling pathway which triggers liver regeneration process

Almost every human organ has a poor ability to regenerate, notable exceptions are liver, skin, gut, etc. Molecular and cellular underpinnings of liver regeneration might pave the way for novel treatments concerned with chronic liver disorder. Such treatments would eliminate the disadvantages of liver transplantation, such as a scarcity of donor organs, a lengthy waitlist, significant medical expenses, surgical complications, and the necessity for lifelong immunosuppressive medications. Advancement in the development of regenerative therapy is giving hope to those suffering from end-stage liver disorder. The regeneration process is unique, intricate, and well coordinated, which involve the interaction of numerous signaling pathways, cytokines, and growth factor. Various signaling pathways for liver regeneration are HO-1/BER pathway, Tweak/Fn14 signaling pathway, Hippo pathway, Wnt/beta-catenin pathway, Hedgehog signaling pathway, bile acids repairing pathway, serotonin (5HT) pathway, estrogen pathway, thyrotropin-releasing hormone (TRH) pathway, insulin repairing pathway, etc. The in vitro scientific literature revealed that numerous GSK-3 β inhibitors (LY 2090314, AR-A014418, Tideglusib, Solasodine, CHIR99021, 9-ING-41, SB-216763) play an important role in stimulating the liver regeneration process. Similarly, from the above discussion, the direction is highlighted to emphasize the proposed molecular Wnt/β-catenin signaling pathway which is associated with GSK-3 β inhibition for the induction of the repairing and regeneration process.

Investigation the Effect of Encapsulated Bromelain Enzyme in Magnetic Carbon Nanotubes on Colorectal Cancer Cells

Background: Bromelain (BL) is an enzyme extracted from Ananas comosus, which has been known for its therapeutic properties. Objectives: The anticarcinogenic activity of BL was examined with and without the presence of magnetic carbon nanotubes (MCNTs) against HT-29 colorectal cancer cells. Methods: The operational factors affecting BL adsorption, such as contact time (30, 60, 90, 120, and 180 min), adsorbent dosage (1 g/L and 5 g/L), initial bromelain concentration (50, 150, and 300 mg/L), and temperature (35 and 50°C) were studied in details. Then, cancer cells were exposed to various BL concentrations (0.1, 1, 10, and 100 μg/mL), and the cell viability was determined by methylthiazol tetrazolium (MTT) assay after 24, 48, and 72 h. Results: The highest adsorption of BL on nanotubes was at 41.62 mg/L and achieved at 35°C and 90 min at the initial concentration of 50 mg/L and 1 g/L of MCNTs. The adsorption followed the Freundlich model and second-order kinetics. The results indicated that MCNTs could be a potential effective adsorbent for the removal of BL. Conclusions: MTT assay indicated that BL at a concentration of 100 μg/mL alone and in combination with MCNTs efficiently inhibited the HT-29 cancerous cells. However, encapsulated BL had a considerable advantage of slow delivery, which is favorable for cancer treatment.

Plant-Derived Natural Products in Cancer Research: Extraction, Mechanism of Action, and Drug Formulation

Cancer is one of the main causes of death globally and considered as a major challenge for the public health system. The high toxicity and the lack of selectivity of conventional anticancer therapies make the search for alternative treatments a priority. In this review, we describe the main plant-derived natural products used as anticancer agents. Natural sources, extraction methods, anticancer mechanisms, clinical studies, and pharmaceutical formulation are discussed in this review. Studies covered by this review should provide a solid foundation for researchers and physicians to enhance basic and clinical research on developing alternative anticancer therapies.

pH-sensitive bromelain nanoparticles by ortho ester crosslinkage for enhanced doxorubicin penetration in solid tumor

Dense extracellular matrix (ECM) is a primary obstacle that restrains the permeation of therapeutic drugs in tumor tissues. Degrading ECM with bromelain (Br) to increase drug penetration is an attractive strategy to enhance antitumor effects. However, the poor stability in circulation and potential immunogenicity severely limit their applications. In this work, a novel pH-sensitive nanocarrier was prepared by crosslinking Br with an ortho ester-based crosslink agent, and Br still retained a certain ability to degrade ECM after crosslinking. The nanoparticles showed higher DOX release rate than non-sensitive nanoparticles, and DOX release amount reached to 86% at pH 5.5 within 120 h. In vivo experiments revealed that the pH-sensitive nanoparticles could be degraded in mildly acidic condition, and the released Br further promoted nanoparticles penetration in tumor parenchyma via in situ hydrolysis of ECM. Furthermore, Br itself could inhibit the proliferation of tumor cells at high concentration, and produce synergistic antitumor effects with DOX. Finally, tumor growth inhibition of these nanoparticles reached to 62.5%. Overall, the bromelain-based pH-sensitive nanoparticles can be potential drug carriers for efficient drug delivery and tumor treatment.

Effect of Polysaccharide Sources on the Physicochemical Properties of Bromelain-Chitosan Nanoparticles

Bromelain, a set of proteolytic enzymes potential pharmaceutical applications, was encapsulated in chitosan nanoparticles to enhance enzyme stability, and the effect of different chitosan sources was evaluated. Chitosan types (i.e., low molecular weight chitosan, chitosan oligosaccharide lactate, and chitosan from shrimp shells) produced nanoparticles with different physicochemical properties, however in all cases, particle size and zeta potential decreased, and polydispersity index increased after bromelain addition. Bromelain encapsulation was higher than 84% and 79% for protein content and enzymatic activity, respectively, with low molecular weight chitosan presenting the highest encapsulation efficiency. Nanoparticle suspension was also tested for accelerated stability and rheological behavior. For the chitosan-bromelain nanoparticles, an instability index below 0.3 was recorded and, in general, the loading of bromelain in chitosan nanoparticles decreased the cohesiveness of the final suspension.

Bromelain-loaded nanoparticles: A comprehensive review of the state of the art

Stem bromelain is a common available cysteine protease derived from pineapple (Ananas comosus L.). Bromelain finds widespread applications in several areas, such as medicine, health, food, and cosmetics, and its strong proteolytic activity supports its future application in many additional fields. However, most proteins and/or enzymes are fragile, leading to important considerations about increase storage and operational stability to enable their practical application. In this scenario, the use of nanoparticles to deliver proteins is increasing exponentially, given that these systems are capable of enhance active's stability, solubility and permeability, and decrease toxicity. In the pharmaceutical nanotechnology field, bromelain has played different roles and thus this paper aims to review the available literature for the use of nanoparticles and bromelain.