Hydrogen-rich solution alleviates acute radiation pneumonitis by regulating oxidative stress and macrophages polarization.

This study was aimed to investigate the effect of hydrogen-rich solution (HRS) on acute radiation pneumonitis (ARP) in rats. The ARP model was induced by X-ray irradiation. Histopathological changes were assessed using HE and Masson stains. Inflammatory cytokines were detected by ELISA. Immunohistochemistry and flow cytometry were performed to quantify macrophage (CD68) levels and the M2/M1 ratio. Western blot analysis, RT-qPCR, ELISA and flow cytometry were used to evaluate mitochondrial oxidative stress injury indicators. Immunofluorescence double staining was performed to colocalize CD68/LC3B and p-AMPK-α/CD68. The relative expression of proteins associated with autophagy activation and the adenosine 5'-monophosphate-activated protein kinase/mammalian target of rapamycin/Unc-51-like kinase 1 (AMPK/mTOR/ULK1) signaling pathway were detected by western blotting. ARP decreased body weight, increased the lung coefficient, collagen deposition and macrophage infiltration and promoted M1 polarization in rats. After HRS treatment, pathological damage was alleviated, and M1 polarization was inhibited. Furthermore, HRS treatment reversed the ARP-induced high levels of mitochondrial oxidative stress injury and autophagy inhibition. Importantly, the phosphorylation of AMPK-α was inhibited, the phosphorylation of mTOR and ULK1 was activated in ARP rats and this effect was reversed by HRS treatment. HRS inhibited M1 polarization and alleviated oxidative stress to activate autophagy in ARP rats by regulating the AMPK/mTOR/ULK1 signaling pathway.

Behavioral dynamics of neuroprotective macrophage polarization in neuropathic pain observed by GHz femtosecond laser two-photon excitation microscopy.

Macrophage polarization in neurotoxic (M1) or neuroprotective (M2) phenotypes is known to play a significant role in neuropathic pain, but its behavioral dynamics and underlying mechanism remain largely unknown. Two-photon excitation microscopy (2PEM) is a promising functional imaging tool for investigating the mechanism of cellular behavior, as using near-infrared excitation wavelengths is less subjected to light scattering. However, the higher-order photobleaching effect in 2PEM can seriously hamper its applications to long-term live-cell studies. Here, we demonstrate a GHz femtosecond (fs) 2PEM that enables hours-long live-cell imaging of macrophage behavior with reduced higher-order photobleaching effect-by leveraging the repetition rate of fs pulses according to the fluorescence lifetime of fluorophores. Using this new functional 2PEM platform, we measure the polarization characteristics of macrophages, especially the long-term cellular behavior in efferocytosis, unveiling the dynamic mechanism of neuroprotective macrophage polarization in neuropathic pain. These efforts can create new opportunities for understanding long-term cellular dynamic behavior in neuropathic pain, as well as other neurobiological problems, and thus dissecting the underlying complex pathogenesis.

Regulation of Cell Polarity and Tissue Architecture in Epidermal Aging and Cancer.

The mammalian skin is essential to protect the organism from external damage while at the same time enabling communication with the environment. Aging compromises skin function and regeneration, which is further exacerbated by external influences, such as UVR from the sun. Aging and UVR are also major risk factors contributing to the development of skin cancer. Whereas aging research traditionally has focused on the role of DNA damage and metabolic and stress pathways, less is known about how aging affects tissue architecture and cell dynamics in skin homeostasis and regeneration and whether changes in these processes promote skin cancer. This review highlights how key regulators of cell polarity and adhesion affect epidermal mechanics, tissue architecture, and stem cell dynamics in skin aging and cancer.

Implications of ionizing radiation on pollen performance in comparison with diverse models of polar cell growth.

Research concerning the effects of ionizing radiation (IR) on plant systems is essential for numerous aspects of human society, as for instance, in terms of agriculture and plant breeding, but additionally for elucidating consequences of radioactive contamination of the ecosphere. This comprehensive survey analyses effects of x- and γ-irradiation on male gametophytes comprising primarily in vitro but also in vivo data of diverse plant species. The IR-dose range for pollen performance was compiled and 50% inhibition doses (ID50 ) for germination and tube growth were comparatively related to physiological characteristics of the microgametophyte. Factors influencing IR-susceptibility of mature pollen and polarized tube growth were evaluated, such as dose-rate, environmental conditions, or species-related variations. In addition, all available reports suggesting bio-positive IR-effects particularly on pollen performance were examined. Most importantly, for the first time influences of IR specifically on diverse phylogenetic models of polar cell growth were comparatively analysed, and thus demonstrated that the gametophytic system of pollen is extremely resistant to IR, more than plant sporophytes and especially much more than comparable animal cells. Beyond that, this study develops hypotheses regarding a molecular basis for the extreme IR-resistance of the plant microgametophyte and highlights its unique rank among organismal systems.

Magnetic Stimulation Drives Macrophage Polarization in Cell to-Cell Communication with IL-1ß Primed Tendon Cells.

Inflammation is part of the natural healing response, but it has been simultaneously associated with tendon disorders, as persistent inflammatory events contribute to physiological changes that compromise tendon functions. The cellular interactions within a niche are extremely important for healing. While human tendon cells (hTDCs) are responsible for the maintenance of tendon matrix and turnover, macrophages regulate healing switching their functional phenotype to environmental stimuli. Thus, insights on the hTDCs and macrophages interactions can provide fundamental contributions on tendon repair mechanisms and on the inflammatory inputs in tendon disorders. We explored the crosstalk between macrophages and hTDCs using co-culture approaches in which hTDCs were previously stimulated with IL-1ß. The potential modulatory effect of the pulsed electromagnetic field (PEMF) in macrophage-hTDCs communication was also investigated using the magnetic parameters identified in a previous work. The PEMF influences a macrophage pro-regenerative phenotype and favors the synthesis of anti-inflammatory mediators. These outcomes observed in cell contact co-cultures may be mediated by FAK signaling. The impact of the PEMF overcomes the effect of IL-1ß-treated-hTDCs, supporting PEMF immunomodulatory actions on macrophages. This work highlights the relevance of intercellular communication in tendon healing and the beneficial role of the PEMF in guiding inflammatory responses toward regenerative strategies.

Attenuation of the inflammatory response and polarization of macrophages by photobiomodulation.

In spinal cord injury (SCI), inflammation is a major mediator of damage and loss of function and is regulated primarily by the bone marrow-derived macrophages (BMDMs). Photobiomodulation (PBM) or low-level light stimulation is known to have anti-inflammatory effects and has previously been used in the treatment of SCI, although its precise cellular mechanisms remain unclear. In the present study, the effect of PBM at 810 nm on classically activated BMDMs was evaluated to investigate the mechanisms underlying its anti-inflammatory effects. BMDMs were cultured and irradiated (810 nm, 2 mW/cm2) following stimulation with lipopolysaccharide and interferon-γ. CCK-8 assay, 2',7'-dichlorofluorescein diacetate assay, and ELISA and western blot analysis were performed to measure cell viability, reactive oxygen species production, and inflammatory marker production, respectively. PBM irradiation of classically activated macrophages significantly increased the cell viability and inhibited reactive oxygen species generation. PBM suppressed the expression of a marker of classically activated macrophages, inducible nitric oxide synthase; decreased the mRNA expression and secretion of pro-inflammatory cytokines, tumor necrosis factor alpha, and interleukin-1 beta; and increased the secretion of monocyte chemotactic protein 1. Exposure to PBM likewise significantly reduced the expression and phosphorylation of NF-κB p65 in classically activated BMDMs. Taken together, these results suggest that PBM can successfully modulate inflammation and polarization in classically activated BMDMs. The present study provides a theoretical basis to support wider clinical application of PBM in the treatment of SCI.

Constitutively expressed MHC class Ib molecules regulate macrophage M2b polarization and sepsis severity in irradiated mice.

Macrophages can change their physiology in response to microenvironmental signals. This differentiation into classically activated M1 or alternatively activated M2 macrophages is known as polarization. In this study, we isolated bone marrow-derived macrophages from ß2m-deficient (deficient in both MHC class Ia and Ib) and Kb Db -deficient (deficient only in MHC class Ia) mice and found that ß2m-deficient macrophages showed a significantly lower M2b polarization efficiency. In addition, the absence of constitutive MHC class Ib expression decreased the stability of the Notch-1 intracellular domain. Finally, we found that ß2m-deficient mice exposed to irradiation showed reduced bacterial translocation and sepsis severity. Overall, our study demonstrates that MHC class Ib molecules are essential for M2b macrophage polarization and suggests that MHC class Ib molecules play an important role during infection-induced innate immunity.

Photobiomodulation Therapy Inhibit the Activation and Secretory of Astrocytes by Altering Macrophage Polarization.

Spinal cord injury (SCI) stimulates reactive astrogliosis and the infiltration of macrophages, which interact with each other at the injured area. We previously found Photobiomodulation (PBM) significantly decreases the number of M1 macrophages at the injured area of SCI. But the exact nature of the astrocyte response following PBM and relationship with the macrophage have not been explored in detail. In this study, a BALB/c mice model with standardized bilateral spinal cord compression and a macrophage-astrocyte co-culture model were applied to study effects of PBM on astrocytes. Results showed that PBM inhibit the expression of the astrocyte markers glial fibrillary acidic protein (GFAP) and the secretion of chondroitin sulfate proteoglycans (CSPG) in the para-epicenter area, decrease the number of M1 macrophage in vivo. The in vitro experiments indicated M1 macrophages promote the cell viability of astrocytes and the expression of CSPG. However, PBM significantly inhibited the expression of GFAP, decreased activation of astrocyte, and downregulated the expression of CSPG by regulating M1 macrophages. These results demonstrate that PBM may regulate the interaction between macrophages and astrocytes after spinal cord injury, which inhibited the formation of glial scar.

Electric Polarization of Soft Biological Tissues Induced by Ultrasound Waves.

Ultrasound irradiation makes it possible to generate alternating electric polarization through the electromechanical coupling of materials. It follows that electromagnetic fields are often emitted to the surrounding environment when materials are acoustically stimulated. We investigate the acoustically stimulated electromagnetic (ASEM) response of soft biological tissues. The ASEM signal is detected through a capacitive resonant antenna tuned to the MHz frequency of the irradiated ultrasound waves. The signal is well explained by the stress-induced polarization, which responds linearly to the applied acoustic stress. Induced polarization is clearly observed in the Achilles tendon, aortic wall, and aortic valve samples, whereas it is small in adipose tissue and myocardium samples, indicating that fibrous tissues exhibit electromechanical coupling.

Physiological strength electric fields modulate human T cell activation and polarisation.

The factors and signals driving T cell activation and polarisation during immune responses have been studied mainly at the level of cells and chemical mediators. Here we describe a physical driver of these processes in the form of physiological-strength electric fields (EFs). EFs are generated at sites where epithelium is disrupted (e.g. wounded skin/bronchial epithelia) and where T cells frequently are present. Using live-cell imaging, we show human primary T cells migrate directionally to the cathode in low strength (50/150 mV/mm) EFs. Strikingly, we show for the first time that EFs significantly downregulate T cell activation following stimulation with antigen-activated APCs or anti-CD3/CD28 antibodies, as demonstrated by decreased IL-2 secretion and proliferation. These EF-induced functional changes were accompanied by a significant dampening of CD4+ T cell polarisation. Expression of critical markers of the Th17 lineage, RORγt and IL-17, and the Th17 polarisation mediator phospho-STAT3 were reduced significantly, while STAT1, ERK and c-Jun phosphorylation were comparatively unaffected suggesting STAT3 modulation by EFs as one mechanism driving effects. Overall, we identify electrical signals as important contributors to the co-ordination and regulation of human T cell functions, paving the way for a new research area into effects of naturally occurring and clinically-applied EFs in conditions where control of T cell activity is paramount.

Monocyte Polarization is Altered by Total-Body Irradiation in Male Rhesus Macaques: Implications for Delayed Effects of Acute Radiation Exposure.

Radiation-induced fibrosis (RIF) is a common delayed effect of acute ionizing radiation exposure (DEARE) affecting diverse tissues including the heart, lungs, liver and skin, leading to reduced tissue function and increased morbidity. Monocytes, which may be classified into classical (CD14++, CD16-), intermediate (CD14++, CD16+) and non-classical (CD14+/low, CD16++) subtypes in humans and non-human primates (NHPs), and monocyte-derived macrophages may play an integral role in the pathogenesis of RIF. We tested the hypothesis that moderate to high levels of total-body exposure to radiation would alter monocyte polarization and produce phenotypes that could promote multi-organ fibrosis in a wellestablished NHP model of DEARE. Subjects were 16 young adult male rhesus macaques, ten of which were exposed to high-energy, 4 Gy X-ray total-body irradiation (TBI) and six that received sham irradiation (control). Total monocytes assessed by complete blood counts were 89% depleted in TBI animals by day 9 postirradiation (P < 0.05), but recovered by day 30 postirradiation and did not differ from control levels thereafter. Monocytes were isolated from peripheral blood mononuclear cells (PBMCs) and sorted into classical, intermediate and non-classical subsets using fluorescence-activated cell sorting (FACS) prior to and at 6 months post-TBI. At 6 months postirradiation, monocyte polarization shifted towards lower classical (92% → 86%) and higher intermediate (7% → 12%) and non-classical monocyte subsets (0.6% → 2%) (all P < 0.05) in TBI animals compared to baseline. No change in monocyte subsets was observed in control animals. Transcriptional profiles in classical and intermediate monocyte subsets were assessed using RNAseq. Classical monocyte gene expression did not change significantly over time or differ cross-sectionally between TBI and control groups. In contrast, significant numbers of differentially expressed genes (DEGs) were detected in intermediate monocyte comparisons between the TBI animals and all animals at baseline (304 DEGs), and in the TBI versus control animals at 6 months postirradiation (67 DEGs). Intermediate monocytes also differed between baseline and 6 months in control animals (147 DEGs). Pathway analysis was used to identify genes within significant canonical pathways, yielding 52 DEGs that were specific to irradiated intermediate monocytes. These DEGs and significant canonical pathways were associated with pro-fibrotic and anti-inflammatory signaling pathways that have been noted to induce M2 macrophage polarization. These findings support the hypothesis that TBI may alter monocyte programming and polarization towards a profibrotic phenotype, providing a novel target opportunity for therapies to inhibit or prevent RIF.

Near-Infrared Light-Activated DNA-Agonist Nanodevice for Nongenetically and Remotely Controlled Cellular Signaling and Behaviors in Live Animals.

Optogenetics provides promising tools for the precise control of receptor-mediated cell behaviors in a spatiotemporal manner. Yet, most photoreceptors require extensive genetic manipulation and respond only to ultraviolet or visible light, which are suboptimal for in vivo applications because they do not penetrate thick tissues. Here we report a novel near-infrared light-activated DNA agonist (NIR-DA) nanodevice for nongenetic manipulation of cell signaling and phenotype in deep tissues. This nanodevice is prepared by conjugating a preinactivated DNA agonist onto the gold nanorods (AuNRs). Upon NIR light treatment, the DNA agonist is released through the localized surface plasmon resonance (LSPR)-based photothermal effect of AuNRs and becomes active. The active DNA agonist dimerizes the DNA-modified chimeric or native receptor tyrosine kinase (RTK) on cell surfaces and activates downstream signal transduction in live cells. Such NIR-DA activation of RTK signaling enables the control of cytoskeletal remodeling, cell polarization, and directional migration. Furthermore, we demonstrate that the NIR-DA system can be used in vivo to mediate RTK signaling and skeletal muscle satellite cell migration and myogenesis, which are critical cellular behaviors in the process of skeletal muscle regeneration. Thus, the NIR-DA system offers a powerful and versatile platform for exogenous modulation of deep tissues for purposes such as regenerative medicine.

Oncogenic transformation of normal breast epithelial cells co-cultured with cancer cells.

The heterogeneity in human breast cancer poses a challenge for effective treatment. Better understanding of tumor initiation and development will help to resolve this problem. Current models explaining intratumoral diversity include cancer stem cells, clonal evolution and cancer cell dedifferentiation and reprogramming. Herein, a new model, cancer transmission, is proposed to explain cancer heterogeneity. We found breast cancer cells (MCF10A.NeuT) were capable of transforming normal mammary epithelial cells (MCF10A). The transformed cells exhibited cancerous properties including enhanced proliferation and migration, loss of apical-basal polarity and depolarized acini structure associated with epithelial-mesenchymal transition (EMT). The transformed MCF10A cells displayed distinct EMT characteristics compared to parental cells. We further showed that cancer cell-secreted factors were sufficient to induce cancerous transformation of normal cells. Furthermore, transformed cells were resistant to radiation treatment, providing new insights into mechanisms underlying therapeutic resistance.

Analyzing Rho GTPase-Dependent Processes During Cell Polarization in Brown Algae.

Zygotes of the fucoid brown algae are useful models for investigating the molecular and cellular mechanisms of cell polarization. These organisms are abundant in the marine intertidal zone, where they grow firmly anchored to rocks. In response to environmental cues like sunlight, zygotes generate asymmetries within the cell that ultimately establish an axis of growth. The transduction of these cues relies on Rac1-mediated signaling that remodels the actin cytoskeleton, alters patterns of endocytosis and secretion, and ultimately prepares the zygote for localized (tip) growth. This chapter presents protocols for obtaining synchronous populations of zygotes, and for detecting changes in filamentous actin arrays, endomembrane patterns, and secretion patterns that occur during light-induced polarization.

Photodynamic activity of Temoporfin nanoparticles induces a shift to the M1-like phenotype in M2-polarized macrophages.

The monocyte/macrophage cell lineage reveals an enormous plasticity, which is required for tissue homeostasis, but is also undermined in various disease states, leading to a functional involvement of macrophages in major human diseases such as atherosclerosis and cancer. We recently generated in vivo evidence that crystalline, nonfluorescent nanoparticles of the hydrophobic porphyrin-related photosensitizer Aluminum phthalocyanine are selectively dissolved and thus may be used for specific fluorescent labelling of rejected, but not of accepted xenotransplants. This led us to hypothesize that nanoparticles made of planar photosensitizers such as porphyrins and chlorins were preferentially taken up and dissolved by macrophages, which was verified by in vitro studies. Here, using an in vitro system for macrophage differentiation/polarization of the human monocyte THP-1 cell line, we demonstrate differential uptake/dissolution of Temoporfin-derived nanoparticles in polarized macrophages, which resulted in differential photosensitivity. More importantly, low dose photodynamic sensitization using Temoporfin nanoparticles can be used to trigger M1 re-polarization of THP-1 cells previously polarized to the M2 state. Thus, sublethal photodynamic treatment using Temoporfin nanoparticles might be applied to induce a phenotypic shift of tumor-associated macrophages for the correction of an immunosuppressive microenvironment in the treatment of cancer, which may synergize with immune checkpoint inhibition.

Optogenetic activation of Plexin-B1 reveals contact repulsion between osteoclasts and osteoblasts.

During bone remodelling, osteoclasts induce chemotaxis of osteoblasts and yet maintain spatial segregation. We show that osteoclasts express the repulsive guidance factor Semaphorin 4D and induce contact inhibition of locomotion (CIL) in osteoblasts through its receptor Plexin-B1. To examine causality and elucidate how localized Plexin-B1 stimulation may spatiotemporally coordinate its downstream targets in guiding cell migration, we develop an optogenetic tool for Plexin-B1 designated optoPlexin. Precise optoPlexin activation at the leading edge of migrating osteoblasts readily induces local retraction and, unexpectedly, distal protrusions to steer cells away. These morphological changes are accompanied by reorganization of Myosin II, PIP3, adhesion and active Cdc42. We attribute the resultant repolarization to RhoA/ROCK-mediated redistribution of ß-Pix, which activates Cdc42 and promotes protrusion. Thus, our data demonstrate a causal role of Plexin-B1 for CIL in osteoblasts and reveals a previously unknown effect of Semaphorin signalling on spatial distribution of an activator of cell migration.

Radiation-Induced RhoGDIß Cleavage Leads to Perturbation of Cell Polarity: A Possible Link to Cancer Spreading.

The equilibrium between proliferation and apoptosis is tightly balanced to maintain tissue homeostasis in normal tissues and even in tumors. Achieving and maintaining such a balance is important for cancer regrowth and spreading after cytotoxic treatments. Caspase-3 activation and tumor cell death following anticancer therapy as well as accompanying cell death pathways are well characterized, but their association to homeostasis of cancerous tissue and tumor progression remains poorly understood. Here we proposed a novel mechanism of cancer spreading induced by caspase-3. RhoGDIß, known as a direct cleavage substrate of caspase-3, is overexpressed in many epithelial cancers. The N-terminal-truncated RhoGDIß (ΔN-RhoGDIß) is accumulated in caspase-3-activated cells. Stable expression of ΔN-RhoGDIß in HeLa cells did not induce apoptosis, but impaired directional cell migration in a wound-healing assay accompanied by a perturbed direction of cell division at the wound edge. Subcellular protein fractionation experiments revealed that ΔN-RhoGDIß but not wild-type RhoGDIß was present in the detergent-soluble cytoplasmic and nuclear fractions and preferentially associated with Cdc42. Furthermore, Cdc42 activity was constitutively inhibited by stable expression of ΔN-RhoGDIß, resulting in increased radiation-induced compensatory proliferation linking to RhoA activation. Thus, ΔN-RhoGDIß dominant-negatively regulates Cdc42 activity and contributes to loss of polarity-related functions. The caspase-3-cleaved RhoGDIß is a possible determinant to promote cancer spreading due to deregulation of directional organization of tumor cell population and inhibition of default equilibrium between proliferation and apoptosis after cytotoxic damage. J. Cell. Physiol. 231: 2493-2505, 2016. © 2016 Wiley Periodicals, Inc.

Effect of Phenylephrine Pretreatment on the Expressions of Aquaporin 5 and c-Jun N-Terminal Kinase in Irradiated Submandibular Gland.

Radiotherapy for malignant tumors of the head and neck commonly leads to radiation-induced sialadenitis as a result of radiation-induced salivary gland dysfunction. We demonstrated previously that phenylephrine could protect the irradiated submandibular gland against apoptosis, although the mechanism is unclear. In this study, we investigated the influence of phenylephrine pretreatment on the expressions of aquaporin 5 (AQP5) and c-Jun N-terminal kinase (JNK) that were presumed to have a role in radiation-induced salivary gland dysfunction. Rats pretreated with phenylephrine (5 mg/kg) were locally irradiated (20 Gy) in the head and neck region. The submandibular glands were removed on day 7 after irradiation. The expression of AQP5 and activation of JNK were measured by immunohistochemistry and Western blot. The localization of AQP5 at the apical and lateral plasma membrane of acinar cells was significantly reduced by irradiation, but markedly enhanced with phenylephrine pretreatment. The protein expression of AQP5 was decreased by 84.91% in irradiated glands, whereas it was fully recovered to the control level in phenylephrine-pretreated glands. Moreover, many acinar, ductal and granular convoluted tubular cells in the irradiated glands exhibited intense immunoreactivity for p-JNK, while in the phenylephrine-pretreated irradiated glands, only a few acinar cells exhibited very faint immunoreactivity for p-JNK. The protein expression level of p-JNK was increased by 41.65% in the irradiated alone glands, but was significantly decreased in the phenylephrine-pretreated irradiated glands. These results suggest that the protective mechanism of phenylephrine might be related to the improved expression of AQP5 and decreased activation of JNK. Pretreatment with phenylephrine in patients undergoing radiotherapy may provide a helpful strategy for suppression of radiation-induced sialadenitis.

Photothermal cellular stimulation in functional bio-polymer interfaces.

Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications, bearing a huge potential, from basic researches to clinical applications. In particular, light sensitive conjugated polymers can be exploited as a new approach for optical modulation of cellular activity. In this work we focus on light-induced changes in the membrane potential of Human Embryonic Kidney (HEK-293) cells grown on top of a poly(3-hexylthiophene) (P3HT) thin film. On top of a capacitive charging of the polymer interface, we identify and fully characterize two concomitant mechanisms, leading to membrane depolarization and hyperpolarisation, both mediated by a thermal effect. Our results can be usefully exploited in the creation of a new platform for light-controlled cell manipulation, with possible applications in neuroscience and medicine.

Aging-like changes in the transcriptome of irradiated microglia.

Whole brain irradiation remains important in the management of brain tumors. Although necessary for improving survival outcomes, cranial irradiation also results in cognitive decline in long-term survivors. A chronic inflammatory state characterized by microglial activation has been implicated in radiation-induced brain injury. We here provide the first comprehensive transcriptional profile of irradiated microglia. Fluorescence-activated cell sorting was used to isolate CD11b+ microglia from the hippocampi of C57BL/6 and Balb/c mice 1 month after 10 Gy cranial irradiation. Affymetrix gene expression profiles were evaluated using linear modeling and rank product analyses. One month after irradiation, a conserved irradiation signature across strains was identified, comprising 448 and 85 differentially up- and downregulated genes, respectively. Gene set enrichment analysis demonstrated enrichment for inflammation, including M1 macrophage-associated genes, but also an unexpected enrichment for extracellular matrix and blood coagulation-related gene sets, in contrast previously described microglial states. Weighted gene coexpression network analysis confirmed these findings and further revealed alterations in mitochondrial function. The RNA-seq transcriptome of microglia 24-h postradiation proved similar to the 1-month transcriptome, but additionally featured alterations in apoptotic and lysosomal gene expression. Reanalysis of published aging mouse microglia transcriptome data demonstrated striking similarity to the 1-month irradiated microglia transcriptome, suggesting that shared mechanisms may underlie aging and chronic irradiation-induced cognitive decline. GLIA 2015;63:754-767.