Exosomes derived from Nr-CWS pretreated MSCs facilitate diabetic wound healing by promoting angiogenesis via the circIARS1/miR-4782-5p/VEGFA axis.

Mesenchymal stem cell (MSC)-derived exosomes (Exos) were reported to a prospective candidate in accelerating diabetic wound healing due to their pro-angiogenic effect. MSCs pretreated with chemistry or biology factors were reported to advance the biological activities of MSC-derived exosomes. Hence, this study was designed to explore whether exosomes derived from human umbilical cord MSCs (hucMSCs) preconditioned with Nocardia rubra cell wall skeleton (Nr-CWS) exhibited superior proangiogenic effect on diabetic wound repair and its underlying molecular mechanisms. The results showed that Nr-CWS-Exos facilitated the proliferation, migration and tube formation of endothelial cells in vitro. In vivo, Nr-CWS-Exos exerted great effect on advancing wound healing by facilitating the angiogenesis of wound tissues compared with Exos. Furthermore, the expression of circIARS1 increased after HUVECs were treated with Nr-CWS-Exos. CircIARS1 promoted the pro-angiogenic effects of Nr-CWS-Exos on endothelial cellsvia the miR-4782-5p/VEGFA axis. Taken together, those data reveal that exosomes derived from Nr-CWS-pretreated MSCs might serve as an underlying strategy for diabetic wound treatment through advancing the biological function of endothelial cells via the circIARS1/miR-4782-5p/VEGFA axis.

Strong FtsZ is with the force: mechanisms to constrict bacteria.

FtsZ, the best-known prokaryotic division protein, assembles at midcell with other proteins forming a ring during septation. Widely conserved in bacteria, FtsZ represents the ancestor of tubulin. In the presence of GTP it forms polymers able to associate into multi-stranded flexible structures. FtsZ research is aimed at determining the role of the Z-ring in division, describing the polymerization and potential force-generating mechanisms and evaluating the roles of nucleotide exchange and hydrolysis. Systems to reconstruct the FtsZ ring in vitro have been described and some of its mechanical properties have been reproduced using in silico modeling. We discuss current research in FtsZ, some of the controversies, and finally propose further research needed to complete a model of FtsZ action that reconciles its in vitro properties with its role in division.

The composition of cell wall skeleton and outermost lipids of Mycobacterium vaccae is modified by ethambutol treatment.

Ethambutol (EMB) is a first line drug in tuberculosis treatment inhibiting the biosynthesis of arabinogalactan, which is a component of the mycobacterial cell wall. The growth of Mycobacterium vaccae cells in the presence of EMB increases cell wall permeability, which was monitored by beta-sitosterol biotransformation. GC/MS and GLC/MS (gas chromatography/mass spectrometry) analysis revealed dramatic changes in the content of covalently bound mycolic acids and in molar ratio galactose (Gal) to arabinose (Ara) in the cell envelopes of EMB-treated cells. The detected variations in the compositions of fatty acids indicate that both the cell wall skeleton and outer layer (free lipids) are decomposed due to EMB treatment.

Two receptor theory in innate immune activation: studies on the receptors for bacillus Culmet Guillen-cell wall skeleton.

Activation of the innate immune system is a prerequisite for the maturation of dendritic cells (DC) and macrophages (Mphi) followed by clonal expansion of the lymphocytes, targeting cells expressing "non-self' antigens. Microbes usually have a component competent to activate DC/Mphi for antigen presentation. This component has been called adjuvant, but recently renamed "pathogen-associated molecular pattern" (PAMP) or modulin based on its molecular identification. Here, we propose the hypothesis that DC/Mphi express two sorts of receptors for PAMP, whose signaling pathways lead to a sufficient antigen (Ag)-presenting state. In bacterial infection, a Toll-like receptor (TLR) and an uptake receptor participate in DC maturation and Mphi activation. Likewise, with a number of viruses, two of the receptors, with short consensus repeats (SCR), immunoglobulin-like domains or chemokine receptor-like motifs etc. induce functional modulation of DC/Mphi. In immune therapy for cancer, primary activation of the innate system would be essential for tumor Ag-specific T cell augmentation. Cancer cells express tumor-associated Ag but barely co-express PAMP, which situation does not allow for the activation of innate immune responses. Supplementing tumor-associated Ag with PAMP may be an effective therapy for patients with cancer. Here, we discuss the possibility of an innate immune therapy for cancer with reference to bacillus Culmet Guillen cell-wall skeleton (BCG-CWS).

Altered cell surface hydrophobicity of lipopolysaccharide-deficient mutant of Bradyrhizobium japonicum.

The authors previously isolated a lipopolysaccharide (LPS) deficient Tn5-mutant of Bradyrhizobium japonicum, and subsequently isolated the LPS gene region. In this study the LPS deficiency of B. japonicum was studied in terms of its cell surface characteristics. By monitoring the kinetics of the partition with hexadecane the LPS-mutant was found to be far more hydrophobic than the wild type strain; the partition coefficients were 3.19 min(-1) for the mutant, as compared with only 1.40 min(-1) for the wild type. When the mutant was transformed with the cloned LPS gene, the transformant regained the wild type phenotypes, including the cell surface hydrophobicity (CSH) and LPS profile. A polyacrylamide gel electrophoretic analysis of LPS demonstrated that the O-antigenic part of LPS was completely absent in the mutant. The LPS-mutant of B. japonicum was visually distinguishable from the wild type after a simple centrifugation of the cells.

Colony variation of Helicobacter pylori: pathogenic potential is correlated to cell wall lipid composition.

BACKGROUND: Differences in expression of disease after infection with Helicobacter pylori have so far been connected with host factors and bacterial interstrain variation. In this study, spontaneous and ecology-mediated intrastrain variation was examined. METHODS: Four clinical isolates of H. pylori were shown to give rise to two colony forms. Bacterial morphology was examined by electron microscopy. Bacterial fractions were examined for proteins using ion exchange chromatography and SDS-PAGE; for lipids using thin-layer chromatography, lipid anion-exchange chromatography, column chromatography on silica gel, 31P-NMR, gas chromatography and mass spectrometry. Bacterial in vitro invasiveness and adhesiveness were examined in two different systems, and urease and VacA toxin were assayed by Western blot analysis. RESULTS: H. pylori was shown to give rise to two colony forms: at normal pH the population was dominated by L colonies. One strain was chosen for further studies. Bacteria from L colonies retained VacA toxin and urease, did not invade or adhere to epithelial cells, and contained normal quantities of phosphatidylethanolamine. In a small frequency, spontaneous S colonies were formed. Bacteria from these colonies released VacA and urease, adhered to and invaded epithelial cells and contained increased amounts of lysophosphatidyl ethanolamine and phosphatidyl serine. After addition of HCl to the culture medium (pH6), almost only S colonies were formed. The results demonstrate that environmental factors, such as HCl, can change the bacterial cell wall, and thereby enhance expression of virulence factors of H. pylori in vitro. A similar in vivo variation would have implications for our understanding of the interaction between HCl secretion in the gastric mucosa and H. pylori in the development of peptic ulcer disease.

Antimutagenicity of cell fractions of microorganisms on potent mutagenic pyrolysates.

The inactivation of 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 2-amino-6-methyldipyrido[1,2-a: 3',2'-d]imidazole (Glu-P-1) by binding of mutagenic pyrolysate to fractions of microorganisms (their desmutagenic and bio-antimutagenic activity) was investigated. All strains bound Trp-P-1 effectively, but Glu-P-1 to a lesser extent. The Gram-negative bacteria (GNB) could bind about 10-20 micrograms/mg of Trp-P-1 more than the Gram-positive bacteria (GPB), and about 50-60 micrograms/mg more than the yeasts. The cell wall skeletons of all strains tested had great binding ability, but in the cytoplasm of all strains tested it was lower. The peptidoglycan, outer membrane, and glucan isolate from the cell wall skeletons showed the highest binding ability to Trp-P-1. The cell wall skeletons of the tested strains greatly inhibited the mutagenicity induced by Trp-P-1, and to a lower extent that of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). Although the cultured broth and solution of cells extracted by phosphate buffer (pH 7.0) showed antimutagenicity against Trp-P-1, this activity was lower than the binding of Trp-P-1 to the cells. The cultured broth and freeze-dried cytoplasms of yeast cells showed bio-antimutagenicity towards Trp-P-1, but those of all bacteria tested did not.