Effects of antibiotic treatment and phagocyte infiltration on development of Pseudomonas aeruginosa biofilm:Insights from the application of a novel PF hydrogel model in vitro and in vivo

Background and purpose: Bacterial biofilm infections are major health issues as the infections are highly tolerant to antibiotics and host immune defenses. Appropriate biofilm models are important to develop and improve to make progress in future biofilm research. Here, we investigated the ability of PF hydrogel material to facilitate the development and study of Pseudomonas aeruginosa biofilms in vitro and in vivo. Methods: Wild-type P. aeruginosa PAO1 bacteria were embedded in PF hydrogel situated in vitro or in vivo, and the following aspects were investigated: 1) biofilm development; 2) host immune response and its effect on the bacteria; and 3) efficacy of antibiotic treatment. Results: Microscopy demonstrated that P. aeruginosa developed typical biofilms inside the PF hydrogels in vitro and in mouse peritoneal cavities where the PF hydrogels were infiltrated excessively by polymorphonuclear leukocytes (PMNs). The bacteria remained at a level of ~106 colony-forming unit (CFU)/hydrogel for 7 days, indicating that the PMNs could not eradicate the biofilm bacteria. β-Lactam or aminoglycoside mono treatment at 64× minimal inhibitory concentration (MIC) killed all bacteria in day 0 in vitro biofilms, but not in day 1 and older biofilms, even at a concentration of 256× MIC. Combination treatment with the antibiotics at 256× MIC completely killed the bacteria in day 1 in vitro biofilms, and combination treatment in most of the cases showed significantly better bactericidal effects than monotherapies. However, in the case of the established in vivo biofilms, the mono and combination antibiotic treatments did not efficiently kill the bacteria. Conclusion: Our results indicate that the bacteria formed typical biofilms in PF hydrogel in vitro and in vivo and that the biofilm bacteria were tolerant against antibiotics and host immunity. The PF hydrogel biofilm model is simple and easy to fabricate and highly reproducible with various application possibilities. We conclude that the PF hydrogel biofilm model is a new platform that will facilitate progress in future biofilm investigations, as well as studies of the efficacy of new potential medicine against biofilm infections.</p

Effects of antibiotic treatment and phagocyte infiltration on development of Pseudomonas aeruginosa biofilm—Insights from the application of a novel PF hydrogel model in vitro and in vivo

Background and purposeBacterial biofilm infections are major health issues as the infections are highly tolerant to antibiotics and host immune defenses. Appropriate biofilm models are important to develop and improve to make progress in future biofilm research. Here, we investigated the ability of PF hydrogel material to facilitate the development and study of Pseudomonas aeruginosa biofilms in vitro and in vivo.MethodsWild-type P. aeruginosa PAO1 bacteria were embedded in PF hydrogel situated in vitro or in vivo, and the following aspects were investigated: 1) biofilm development; 2) host immune response and its effect on the bacteria; and 3) efficacy of antibiotic treatment.ResultsMicroscopy demonstrated that P. aeruginosa developed typical biofilms inside the PF hydrogels in vitro and in mouse peritoneal cavities where the PF hydrogels were infiltrated excessively by polymorphonuclear leukocytes (PMNs). The bacteria remained at a level of ~106 colony-forming unit (CFU)/hydrogel for 7 days, indicating that the PMNs could not eradicate the biofilm bacteria. β-Lactam or aminoglycoside mono treatment at 64× minimal inhibitory concentration (MIC) killed all bacteria in day 0 in vitro biofilms, but not in day 1 and older biofilms, even at a concentration of 256× MIC. Combination treatment with the antibiotics at 256× MIC completely killed the bacteria in day 1 in vitro biofilms, and combination treatment in most of the cases showed significantly better bactericidal effects than monotherapies. However, in the case of the established in vivo biofilms, the mono and combination antibiotic treatments did not efficiently kill the bacteria.ConclusionOur results indicate that the bacteria formed typical biofilms in PF hydrogel in vitro and in vivo and that the biofilm bacteria were tolerant against antibiotics and host immunity. The PF hydrogel biofilm model is simple and easy to fabricate and highly reproducible with various application possibilities. We conclude that the PF hydrogel biofilm model is a new platform that will facilitate progress in future biofilm investigations, as well as studies of the efficacy of new potential medicine against biofilm infections

Pharmacologic stem cell based intervention as a new approach to osteoporosis treatment in rodents

Background: Osteoporosis is the most prevalent skeletal disorder, characterized by a low bone mineral density (BMD) and bone structural deterioration, leading to bone fragility fractures. Accelerated bone resorption by osteoclasts has been established as a principal mechanism in osteoporosis. However, recent experimental evidences suggest that inappropriate apoptosis of osteoblasts/osteocytes accounts for, at least in part, the imbalance in bone remodeling as occurs in osteoporosis. The aim of this study is to examine whether aspirin, which has been reported as an effective drug improving bone mineral density in human epidemiology studies, regulates the balance between bone resorption and bone formation at stem cell levels. Methods and Findings: We found that T cell-mediated bone marrow mesenchymal stem cell (BMMSC) impairment plays a crucial role in ovariectomized-induced osteoporosis. Ex vivo mechanistic studies revealed that T cell-mediated BMMSC impairment was mainly attributed to the apoptosis of BMMSCs via the Fas/Fas ligand pathway. To explore potential of using pharmacologic stem cell based intervention as an approach for osteoporosis treatment, we selected ovariectomy (OVX)- induced ostoeporosis mouse model to examine feasibility and mechanism of aspirin-mediated therapy for osteoporosis. We found that aspirin can inhibit T cell activation and Fas ligand induced BMMSC apoptosis in vitro. Further, we revealed that aspirin increases osteogenesis of BMMSCs by aiming at telomerase activity and inhibits osteoclast activity in OVX mice, leading to ameliorating bone density. Conclusion: Our findings have revealed a novel osteoporosis mechanism in which activated T cells induce BMMSC apoptosis via Fas/Fas ligand pathway and suggested that pharmacologic stem cell based intervention by aspirin may be a new alternative in osteoporosis treatment including activated osteoblasts and inhibited osteoclasts.Takayoshi Yamaza, Yasuo Miura, Yanming Bi, Yongzhong Liu, Kentaro Akiyama, Wataru Sonoyama, Voymesh Patel, Silvio Gutkind, Marian Young, Stan Gronthos, Anh Le, Cun-Yu Wang, WanJun Chen and Songtao Sh

Un avispón activado por energía solar

Se trata de la primera especie del reino animal descubierta hasta el momento que utiliza radiación solar para sus actividades metabólicas. Los investigadores observaron que los obreros trabajaban más durante los momentos de mayor exposición solar.Gerencia de Comunicación e Imagen Institucional, DNA SICC, INTAFil: Plotkin, Marian. Universidad de Tel-Aviv; Israe

Un avispón activado por energía solar

Se trata de la primera especie del reino animal descubierta hasta el momento que utiliza radiación solar para sus actividades metabólicas. Los investigadores observaron que los obreros trabajaban más durante los momentos de mayor exposición solar.Gerencia de Comunicación e Imagen Institucional, DNA SICC, INTAFil: Plotkin, Marian. Universidad de Tel-Aviv; Israe

Micromorphology and Maturation of the Yellow Granules in the Hornet Gastral Cuticle

The yellow granules in the gastral cuticle of the Oriental hornet Vespa orientalis (Hymenoptera, Vespinae) are located in yellow stripes. In the present study, we focus on the micromorphology and formation of the yellow granules from their inception to their spread in the regions which are destined to acquire a yellow color. The cuticle was observed with several methods of electron microscopy. The results showed that the yellow granules comprise a layer which is 40-45 µm thick, within the total cuticular thickness of 40−45 µm. In the mentioned regions one can see, from above, many apertures of about 0.5 µm in diameter which extends into a peripheral photoreceptor cell. In each yellow granule, one discerns a myoid envelope inside which there are 9 fibrils arranged in a circle. Yellow granules maturation process involves infiltration of canals that give rise to the incipient ball-shaped primary granules which increase in number (as a result of continues budding off the walls of a canal) as the cuticle matures and transform into secondary barrel shaped granules, becoming elongated and then splitting into shorter barrels that fill up the entire area. Preliminary examinations have suggested liver-like function activity within the layer of yellow granules

Micromorphology and Maturation of the Yellow Granules in the Hornet Gastral Cuticle

The yellow granules in the gastral cuticle of the Oriental hornet Vespa orientalis (Hymenoptera, Vespinae) are located in yellow stripes. In the present study, we focus on the micromorphology and formation of the yellow granules from their inception to their spread in the regions which are destined to acquire a yellow color. The cuticle was observed with several methods of electron microscopy. The results showed that the yellow granules comprise a layer which is 40-45 µm thick, within the total cuticular thickness of 40−45 µm. In the mentioned regions one can see, from above, many apertures of about 0.5 µm in diameter which extends into a peripheral photoreceptor cell. In each yellow granule, one discerns a myoid envelope inside which there are 9 fibrils arranged in a circle. Yellow granules maturation process involves infiltration of canals that give rise to the incipient ball-shaped primary granules which increase in number (as a result of continues budding off the walls of a canal) as the cuticle matures and transform into secondary barrel shaped granules, becoming elongated and then splitting into shorter barrels that fill up the entire area. Preliminary examinations have suggested liver-like function activity within the layer of yellow granules