Shaping the microenvironment: Evidence for the influence of a host galaxin on symbiont acquisition and maintenance in the squid-vibrio symbiosis

Most bacterial species make transitions between habitats, such as switching from free-living to symbiotic niches. We provide evidence that a galaxin protein, EsGal1, of the squid Euprymna scolopes participates in both: (i) selection of the specific partner Vibrio fischeri from the bacterioplankton during symbiosis onset and, (ii) modulation of V. fischeri growth in symbiotic maintenance. We identified two galaxins in transcriptomic databases and showed by qRT-PCR that one (esgal1) was dominant in the light organ. Further, esgal1 expression was upregulated by symbiosis, a response that was partially achieved with exposure to symbiont cell-envelope molecules. Confocal immunocytochemistry of juvenile animals localized EsGal1 to the apical surfaces of light-organ epithelia and surrounding mucus, the environment in which V. fischeri cells aggregate before migration into the organ. Growth assays revealed that one repeat of EsGal1 arrested growth of Gram-positive bacterial cells, which represent the cell type first ‘winnowed’ during initial selection of the symbiont. The EsGal1-derived peptide also significantly decreased the growth rate of V. fischeri in culture. Further, when animals were exposed to an anti-EsGal1 antibody, symbiont population growth was significantly increased. These data provide a window into how hosts select symbionts from a rich environment and govern their growth in symbiosis

Fibrosis worsens chronic lymphedema in rodent tissues

© 2015 the American Physiological Society. Secondary lymphedema in humans is a common consequence of lymph node dissection (LND) to treat breast cancer. A peculiar characteristic of the disease is that lifelong swelling often precipitously appears several years after the surgical treatment, often due to an inflammatory stimulus. Although the incidence of secondary lymphedema dramatically increases after radiation therapy, the relationship between fibrotic scarring and the eventual appearance of lymphedema remains unclear. To clarify the role of fibrosis in secondary lymphedema initiation, we chemically increased fibrosis in rodent tissues with bleomycin and assessed the ability of the local lymphatic system to prevent lymphedema, either acutely or in a chronic state induced by inflammation. We found that bleomycin injections exacerbated fibrotic matrix deposition in an acute mouse tail lymphedema model (P \u3c 0.005), reduced wound closure (P \u3c 0.005), and impaired the ability of tail lymphatics to regenerate (P \u3c 0.005) and reduce the swelling (P \u3c 0.05). When fibrosis was worsened with bleomycin after axillary LND in the rat foreleg, the ability of the foreleg lymphatic system to reduce the chronic state swelling induced by stimulated inflammation was severely impaired (P \u3c 0.005). Indocyanine green lymphography in axillary LNDrecovered rat forelegs revealed a worsened lymphatic drainage due to inflammation and bleomycin pretreatment. Although inflammation reduced the drainage of dextran fluid tracer from control forelegs (P \u3c 0.05), the reduction in fluid drainage was more severe after axillary LND when fibrosis was first increased (P \u3c 0.005). These findings demonstrate that fibrosis reduces the lymphatic capacity to functionally regenerate and prevent the chronic appearance of lymphedema

Biodegradable magnesium materials regulate ROS-RNS balance in pro-inflammatory macrophage environment

The relationship between reactive oxygen and nitrogen species (ROS-RNS) secretion and the concomitant biocorrosion of degradable magnesium (Mg) materials is poorly understood. We found that Mg foils implanted short term in vivo (24 h) displayed large amounts of proinflammatory F4/80+/iNOS + macrophages at the interface. We sought to investigate the interplay between biodegrading Mg materials (98.6% Mg, AZ31 & AZ61) and macrophages (RAW 264.7) stimulated with lipopolysaccharide (RAW 264.7LPS) to induce ROS-RNS secretion. To test how these proinflammatory ROS-RNS secreting cells interact with Mg corrosion in vitro, Mg and AZ61 discs were suspended approximately 2 mm above a monolayer of RAW 264.7 cells, either with or without LPS. The surfaces of both materials showed acute (24 h) changes when incubated in the proinflammatory RAW 264.7LPS environment. Mg discs incubated with RAW 264.7LPS macrophages showed greater corrosion pitting, while AZ61 showed morphological and elemental bulk product changes via scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX). X-ray photoelectron spectroscopy (XPS) analysis showed a reduction in the Ca/P ratio of the surface products for AZ61 disc incubated with RAW 264.7LPS, but not the Mg discs. Moreover, RAW 264.7LPS macrophages were found to be more viable in the acute biodegradative environment generated by Mg materials, as demonstrated by calcein-AM and cleaved (active) caspase-3 staining (CC3). LPS stimulation caused an increase in ROS-RNS, and a decrease in antioxidant peroxidase activity. Mg and AZ61 were found to change this ROS-RNS balance, independently of physiological antioxidant mechanisms. The findings highlight the complexity of the cellular driven acute inflammatory responses to different biodegradable Mg, and how it can potentially affect performance of these materials

Biodegradable magnesium materials regulate ROS-RNS balance in pro-inflammatory macrophage environment

The relationship between reactive oxygen and nitrogen species (ROS-RNS) secretion and the concomitant biocorrosion of degradable magnesium (Mg) materials is poorly understood. We found that Mg foils implanted short term in vivo (24 h) displayed large amounts of proinflammatory F4/80+/iNOS + macrophages at the interface. We sought to investigate the interplay between biodegrading Mg materials (98.6% Mg, AZ31 & AZ61) and macrophages (RAW 264.7) stimulated with lipopolysaccharide (RAW 264.7LPS) to induce ROS-RNS secretion. To test how these proinflammatory ROS-RNS secreting cells interact with Mg corrosion in vitro, Mg and AZ61 discs were suspended approximately 2 mm above a monolayer of RAW 264.7 cells, either with or without LPS. The surfaces of both materials showed acute (24 h) changes when incubated in the proinflammatory RAW 264.7LPS environment. Mg discs incubated with RAW 264.7LPS macrophages showed greater corrosion pitting, while AZ61 showed morphological and elemental bulk product changes via scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX). X-ray photoelectron spectroscopy (XPS) analysis showed a reduction in the Ca/P ratio of the surface products for AZ61 disc incubated with RAW 264.7LPS, but not the Mg discs. Moreover, RAW 264.7LPS macrophages were found to be more viable in the acute biodegradative environment generated by Mg materials, as demonstrated by calcein-AM and cleaved (active) caspase-3 staining (CC3). LPS stimulation caused an increase in ROS-RNS, and a decrease in antioxidant peroxidase activity. Mg and AZ61 were found to change this ROS-RNS balance, independently of physiological antioxidant mechanisms. The findings highlight the complexity of the cellular driven acute inflammatory responses to different biodegradable Mg, and how it can potentially affect performance of these materials

Fibrosis worsens chronic lymphedema in rodent tissues

Secondary lymphedema in humans is a common consequence of lymph node dissection (LND) to treat breast cancer. A peculiar characteristic of the disease is that lifelong swelling often precipitously appears several years after the surgical treatment, often due to an inflammatory stimulus. Although the incidence of secondary lymphedema dramatically increases after radiation therapy, the relationship between fibrotic scarring and the eventual appearance of lymphedema remains unclear. To clarify the role of fibrosis in secondary lymphedema initiation, we chemically increased fibrosis in rodent tissues with bleomycin and assessed the ability of the local lymphatic system to prevent lymphedema, either acutely or in a chronic state induced by inflammation. We found that bleomycin injections exacerbated fibrotic matrix deposition in an acute mouse tail lymphedema model (P < 0.005), reduced wound closure (P < 0.005), and impaired the ability of tail lymphatics to regenerate (P < 0.005) and reduce the swelling (P < 0.05). When fibrosis was worsened with bleomycin after axillary LND in the rat foreleg, the ability of the foreleg lymphatic system to reduce the chronic state swelling induced by stimulated inflammation was severely impaired (P < 0.005). Indocyanine green lymphography in axillary LND-recovered rat forelegs revealed a worsened lymphatic drainage due to inflammation and bleomycin pretreatment. Although inflammation reduced the drainage of dextran fluid tracer from control forelegs (P < 0.05), the reduction in fluid drainage was more severe after axillary LND when fibrosis was first increased (P < 0.005). These findings demonstrate that fibrosis reduces the lymphatic capacity to functionally regenerate and prevent the chronic appearance of lymphedema

Corrosion Characteristics Dictate the Long-Term Inflammatory Profile of Degradable Zinc Arterial Implants

There has been considerable recent interest to develop a feasible bioresorbable stent (BRS) metal. Although zinc and its alloys have many potential advantages, the inflammatory response has not been carefully examined. Using a modified wire implantation model, we characterize the inflammatory response elicited by zinc at high purity (4N) [99.99%], special high grade (SHG)[∼99.7%], and alloyed with 1 wt % (Zn-1Al), 3% (Zn-3Al), and 5.5% (Zn-5Al) aluminum. We found that inflammatory cells were able to penetrate the thick and porous corrosion layer that quickly formed around SHG, Zn-1Al, Zn-3Al, and Zn-5Al implants. In contrast, a delayed entrance of inflammatory cells into the corrosion layer around 4N zinc due to a significantly lower corrosion rate was associated with greater fibrous encapsulation, appearance of necrotic regions, and increased macrophage labeling. Interestingly, cell viability at the interface decreased from SHG, to Zn-1Al, and then Zn-3Al, a trend associated with an increased CD68 and CD11b labeling and capsule thickness. Potentially, the shift to intergranular corrosion due to the aluminum addition increased the activity of macrophages. We conclude that the ability of macrophages to penetrate and remain viable within the corrosion layer may be of fundamental importance for eliciting biocompatible inflammatory responses around corrodible metals