Obesity-induced reduced expression of the lncRNA ROIT impairs insulin transcription by downregulation of Nkx6.1 methylation.

AIMS/HYPOTHESIS: Although obesity is a predisposing factor for pancreatic beta cell dysfunction, the mechanisms underlying its negative effect on insulin-secreting cells is still poorly understood. The aim of this study was to identify islet long non-coding RNAs (lncRNAs) involved in obesity-mediated beta cell dysfunction. METHODS: RNA sequencing was performed to analyse the islets of high-fat diet (HFD)-fed mice and those of normal chow-fed mice (NCD). The function in beta cells of the selected lncRNA 1810019D21Rik (referred to in this paper as ROIT [regulator of insulin transcription]) was assessed after its overexpression or knockdown in MIN6 cells and primary islet cells, as well as in siRNA-treated mice. Then, RNA pull-down, RNA immunoprecipitation, coimmunoprecipitation and bisulphite sequencing were performed to investigate the mechanism of ROIT regulation of islet function. RESULTS: ROIT was dramatically downregulated in the islets of the obese mice, as well as in the sera of obese donors with type 2 diabetes, and was suppressed by HNF1B. Overexpression of ROIT in MIN6 cells and islets led to improved glucose homeostasis and insulin transcription. Investigation of the mechanism involved showed that ROIT bound to DNA methyltransferase 3a and caused its degradation through the ubiquitin proteasome pathway, which blocked the methylation of the Nkx6.1 promoter. CONCLUSIONS/INTERPRETATION: These findings functionally suggest a novel link between obesity and beta cell dysfunction via ROIT. Elucidating a precise mechanism for the effect of obesity on lncRNA expression will broaden our understanding of the pathophysiological development of diabetes and facilitate the design of better tools for diabetes prevention and treatment. DATA AVAILABILITY: The raw RNA sequencing data are available from the NCBI Gene Expression Omnibus (GEO series accession number GSE139991).

Inhibition of bacterial adherence to biomaterials by coating antimicrobial peptides with anionic surfactant.

Medical devices are widely used in modern medicine, but their utilities are often limited by the biofilm formation of bacteria that are tolerant to most antibiotics. In this report, antimicrobial peptides (AMPs) were coated onto biomaterials by the aid of surfactant through hydrophobic interactions. To increase the coating efficiency, stability of AMPs in body fluids and spectrum of antimicrobial activity, pairs of AMPs were coated simultaneously onto various substrates, such as silicone, polyurethane and titanium, which are commonly used components of biomedical devices. These coated AMPs exhibited very low cytotoxicity and hemolytic activities because they were gradually released into urine or serum. The AMP pairs, such as T9W + SAAP159 and T9W + RRIKA, coated onto the silicone discs were able to inhibit in vitro bacterial adherence in urine. Most importantly, AMP pairs coated onto the silicone tubing by surfactant SDBS could prevent bacterial adherence to mouse bladder and the silicone tubing implanted within it. These results provide a promising approach towards circumventing urinary catheter-associated infections caused by bacterial adherence.

Anionic Surfactant-Facilitated Coating of Antimicrobial Peptide and Antibiotic Reduces Biomaterial-Associated Infection.

Medical devices are widely used in modern medicine, but the high prevalence of biomaterial-associated infections still presents a major problem. Especially problematic is the formation of biofilms that are tolerant to most antibiotics. In this report, antimicrobial peptides (AMPs) were driven into an amphipathic structure by anionic surfactant. To increase the coating efficacy and spectrum of antimicrobial activity, the AMPs were coated simultaneously with antibiotic, Polymyxin B, by surfactant onto polystyrene, silicone, polyurethane, and titanium which are commonly used with biomedical devices. These coated antimicrobials stably adhered to the substrate and were gradually released into urine and serum. They exhibited high bactericidal activity, but low cytotoxicity and hemolytic activity. Most importantly, the antimicrobials coated onto silicone tubing inhibited the planktonic growth of E. coli in mouse urine and also markedly prevented bacterial adherence to the bladder and the silicone tubing implanted in the bladder. These results provide a promising approach to circumvent catheter-associated infections due to bacterial adherence.

A new biocompatible microemulsion increases extraction yield and bioavailability of Andrographis paniculata.

The purpose of this study was to design and prepare a biocompatible microemulsion of Andrographis paniculata (BMAP) containing both fat-soluble and water-soluble constituents. We determined the contents of active constituents of BMAP and evaluated its bioavailability. The biocompatible microemulsion (BM), containing lecithin and bile salts, was optimized in the present study, showing a good physical stability. The mean droplet size was 19.12 nm, and the average polydispersity index (PDI) was 0.153. The contents of andrographolide and dehydroandrographolide in BMAP, as determined by high performance liquid chromatography (HPLC), were higher than that in ethanol extraction. The pharmacokinetic results of BMAP showed that the AUC0-7 and AUC0→∞ values of BMAP were 2.267 and 27.156 µg·mL(-1)·h(-1), respectively, and were about 1.41-fold and 6.30-fold greater than that of ethanol extraction, respectively. These results demonstrated that the bioavailability of and rographolide extracted by BMAP was significantly higher than that extracted by ethanol. In conclusion, the BMAP preparation displayed ann improved dose form for future clinical applications.