RESUMO
The overuse of antibiotics has resulted in a surge of drug-resistant bacteria, making the pursuit of natural antimicrobials an urgent and significant trend. Encapsulation and nanoparticulation are effective ways to enhance the antibacterial properties of natural drugs. In this study, we encapsulated tannic acid (TA) with chitosan (CS) and poly (lactide-co-glycolide) (PLGA) using the emulsion-solvent evaporation method to enhance the antimicrobial effect of TA. We prepared a bilayer membrane spherical nanoemulsion of TA-PLGA-CS (TPC) with uniform size of 559.87 ± 1.16 nm, and zeta potential of 59.53 ± 1.07 mV. TPC could be stably stored for 90 days at 4°C without affecting the properties of the emulsion, and the minimum bactericidal concentration against four strains of Escherichia coli (E. coli) remained unchanged for 60 d. The results indicated that TPC enhanced the inhibitory effect of TA against E. coli. Scanning electron microscope images revealed that TPC treatment caused damage to the bacterial cell membrane. In addition, in vivo experiments indicated that TPC exhibited a superior therapeutic effect on artificial colibacillosis in chickens infested with Avian pathogenic Escherichia coli, as evidenced by the changes in body weight and a reduction bacterial load in heart. Furthermore, TPC reversed the down-regulation of catalase, glutathione peroxidase1 (GPX1), and GPX7 gene expression levels in intestinal tissues. Compared to the model group, TPC treatment elevated serum glutathione peroxidase activities and lowered myeloperoxidase and lactate dehydrogenase levels, offering antioxidant protection that was slightly better than that of doxycycline hydrochlorid group. In summary, we prepared a novel TA antimicrobial preparation with significant antioxidant potential and inhibitory effect against E. coli both in vitro and in vivo.
RESUMO
Oral delivery of chitosan-coated artesunate (CPA) has been proven to be effective at preventing ulcerative colitis (UC) in mice. However, the anti-inflammatory mechanism is not fully understood. STAT6 is a key transcription factor that promotes anti-inflammatory effects by inducing M2 and Th2 dominant phenotypes, therefore we hypothesized STAT6 might play a key role in the process. To prove it, a STAT6 gene knockout macrophage cell line (STAT6-/- RAW264.7, by CRISPR/Cas9 method), and its corresponding Caco-2/RAW264.7 co-culture system combined with the STAT6 inhibitor (AS1517499, AS) in a mouse UC model were established and studied. The results showed that CPA remarkably suppressed the activation of TLR-4/NF-κB pathway and the mRNA levels of proinflammatory cytokines, while increased the IL-10 levels in RAW264.7. This effect of CPA contributed to the protection of the ZO-1 in Caco-2 which was disrupted upon the stimulation to macrophages. Simultaneously, CPA reduced the expression of CD86 but increase the expression of CD206 and p-STAT6 in LPS-stimulated RAW264.7 cells. However, above alterations were not obvious as in STAT6-/- RAW264.7 and its co-culture system, suggesting STAT6 plays a key role. Furthermore, CPA treatment significantly inhibited TLR-4/NF-κB activation, intestinal macrophage M1 polarization and mucosal barrier injury induced by DSS while promoted STAT6 phosphorylation in the UC mouse model, but this effect was also prominently counteracted by AS. Therefore, our data indicate that STAT6 is a major regulator in the balance of M1/M2 polarization, intestinal barrier integrity and then anti-colitis effects of CPA. These findings broaden our understanding of how CPA fights against UC and imply an alternative treatment strategy for UC via this pathway.
Assuntos
Quitosana , Colite Ulcerativa , Humanos , Camundongos , Animais , Colite Ulcerativa/induzido quimicamente , Colite Ulcerativa/tratamento farmacológico , Colite Ulcerativa/metabolismo , Artesunato/farmacologia , Artesunato/metabolismo , Quitosana/farmacologia , NF-kappa B/metabolismo , Células CACO-2 , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismo , Macrófagos , Anti-Inflamatórios/farmacologia , Modelos Animais de Doenças , Sulfato de Dextrana/efeitos adversos , Fator de Transcrição STAT6/genética , Fator de Transcrição STAT6/metabolismo , Fator de Transcrição STAT6/farmacologiaRESUMO
The purpose of this study was to formulate tee tree oil nanoliposomes (TTONL) and evaluate its characterization and antibacterial activity. TTONL was prepared by thin film hydration and sonication technique, and the preparation conditions were optimized by Box-behnken response surface method. The characterization (morphology, size, zeta potential, and stability) and antibacterial activity of TTONL against Escherichia coli (E. coli) in vitro and in vivo were evaluated. The optimal preparation conditions for TTONL: lecithin to cholesterol mass ratio of 3.7:1, TTO concentration of 0.5%, and pH of the hydration medium of 7.4, which resulted in a TTONL encapsulation rate of 80.31 ± 0.56%. TTONL was nearly spherical in shape and uniform in size, and the average particle size was 227.8 ± 25.3 nm with negative charge. The specific disappearance of the TTO peak in the infrared spectrum suggested the successful preparation of TTONL, which showed high stability at 4°C within 35 d. The result of MIC test found that the nanoliposomes improved antibacterial activity of TTO against various E. coli strains. TTONL exposure in vitro caused different degrees of structural damage to the E. coli. TTONL by oral administration alleviated the clinical symptoms and intestinal lesion of chickens induced with E. coli challenge. Furthermore, TTONL treatment remarkably lowered the mRNA expression of NLRP3 and NF-κB (p65) in the duodenum and cecum of E. coli-infected chickens. In conclusion, the prepared TTONL had good stability and slow-release property with dose-dependent inhibition and killing effects on different strains of E. coli, and exerted a preventive role against chicken colibacillosis through inhibition.
Assuntos
Óleo de Melaleuca , Animais , Óleo de Melaleuca/farmacologia , Óleo de Melaleuca/química , Escherichia coli , Galinhas , Antibacterianos/farmacologia , Antibacterianos/químicaRESUMO
Artesunate (ARS) has been shown to have a protective effect on ulcerative colitis (UC) in mice. However, its lack of targeting and short half-life severely hamper its efficacy. In this study, polylactic acid-glycolic acid copolymer (PLGA) and chitosan (CS) double emulsification solvent volatilisation method was used to prepare a stable nanoemulsion loaded with ARS (CPA). The in vitro drug release profile was detected using dialysis and the potential protective effect was evaluated in an experimental ulcerative colitis (UC) model induced by oral administration of dextran sulphate sodium (DSS). The results suggested that the mean droplet diameter of CPA nanoemulsion is 409.9 ± 9.21 nm, the polydispersity index is 0.17 ± 0.01 and the zeta potential is 40.07 ± 1.65 mV. The cumulative release curve showed the ARS was mainly released at pH 7.4, which is similar to the colonic environment. Oral administration of CPA effectively relieved DSS-induced clinical symptoms by lowering the body weight loss, disease activity index (DAI) score and impressively maintained tight junction protein expression in colon tissue when compared to the blank nanoemulsion control. Meanwhile, CPA remarkably suppressed TLR4/NF-κB pathway activation and mRNA levels of proinflammatory cytokines (IL-1ß, IL-6, and TNF-α) while enhanced levels of IL-10 and CD206. In addition, the effect of CPA was slightly better than that of injecting ARS. Therefore, this study demonstrates a convenient drug delivery system for oral administration of ARS that potentially helps to target colonic tissue and alleviate UC.