Responses In Various Organs Research Articles

The Impact of Fine Particulate Matter on Embryonic Development.

Airborne fine particulate matter (PM2.5) in air pollution has become a significant global public health concern related to allergic diseases. Previous research indicates that PM2.5 not only affects the respiratory system but may also induce systemic inflammation in various tissues. Moreover, its impact may vary among different populations, with potential consequences during pregnancy and in newborns. However, the precise mechanisms through which PM2.5 induces inflammatory reactions remain unclear. This study aims to explore potential pathways of inflammatory responses induced by PM2.5 through animal models and zebrafish embryo experiments. In this study, zebrafish embryo experiments were conducted to analyze the effects of PM2.5 on embryo development and survival, and mouse experimental models were employed to assess the impact of PM2.5 stimulation on various aspects of mice. Wild-type zebrafish embryos were exposed to a PM2.5 environment of 25-400 μg/mL starting at 6 h after fertilization (6 hpf). At 6 days post-fertilization, the survival rates of the 25, 50, 100, and 200 µg/mL groups were 100%, 80, 40%, and 40%, respectively. Zebrafish embryos stimulated with 25 μg/mL of PM2.5 still exhibited successful development and hatching. Additionally, zebrafish subjected to doses of 25-200 μg/mL displayed abnormalities such as spinal curvature and internal swelling after hatching, indicating a significant impact of PM2.5 stimulation on embryo development. In the mouse model, mice exposed to PM2.5 exhibited apparent respiratory overreaction, infiltration of inflammatory cells into the lungs, elevated levels of inflammatory response-related cytokines, and inflammation in various organs, including the liver, lungs, and uterus. Blood tests on experimental mice revealed increased expression of inflammatory and chemotactic cytokines, and GSEA indicated the induction of various inflammatory responses and an upregulation of the TNF-α/NFκB pathway by PM2.5. Our results provide insights into the harmful effects of PM2.5 on embryos and organs. The induced inflammatory responses by PM2.5 may be mediated through the TNF-α/NFκB pathway, leading to systemic organ inflammation. However, whether PM2.5-induced inflammatory responses in various organs and abnormal embryo development are generated through different pathways requires further study to comprehensively clarify and identify potential treatment and prevention methods.

Activation of ERK/NF-kB Pathways Contributes to the Inflammatory Response in Epithelial Cells and Macrophages Following Manganese Exposure.

Different types of metals, including manganese (Mn), are constantly encountered in various environmental matrices due to natural and anthropogenic activities. They induce a sustained inflammatory response in various organs, which is considered to be an important priming event in the pathogenesis of several diseases. Mn-induced neuroinflammation and subsequent neurodegeneration are well recognized. However, emerging data suggest that occupationally and environmentally relevant levels may affect various organs, including the lungs. Therefore, the present study was carried out to investigate the effects of Mn (as Mn2+) exposure on the inflammatory response in human normal bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells, as well as in murine macrophages (J774). Mn2+ exposure significantly induced mRNA and protein expression of various pro-inflammatory mediators (cytokines and chemokines) in all cells compared to corresponding vehicle controls. Furthermore, Mn2+ treatment also led to increased phosphorylation of extracellular-signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-kB) p65 in both epithelial cells and macrophages. As expected, cells treated with inhibitors of ERK1/2 (PD98059) and NF-kB p65 (IMD0354) effectively mitigated the expression of various pro-inflammatory mediators induced by Mn2+, suggesting that ERK/NF-kB pathways have a critical role in the Mn2+-induced inflammatory response. Further, in vivo studies are required to confirm these in vitro findings to support clinical translation.

Microbiota-mediated metabolic perturbations in the gut and brain of mice after microplastic exposure

Microplastics (MPs), emerging environmental toxicants, have drawn attention because of their wide distribution in the environment. Exposure to MPs induces gut microbiota dysbiosis, intestinal barrier dysfunction, metabolic perturbations, and neurotoxicity in different rodents. However, the relationship between MPs, gut microbiota, and the metabolome of the gut and brain in mice remains unclear. In this study, female C57BL/6 mice were orally gavaged with vehicle, 200 nm MP, and 800 nm MP three times per week for four weeks. Cecal contents were collected for gut microbiota analysis using 16S rRNA gene sequencing. Intestinal and brain tissues from mice were used to determine metabolic profiles using liquid chromatography-mass spectrometry (LC-MS). The results showed that MP altered microbiota composition, accompanied by metabolic perturbations in the mouse gut and brain. Specifically, Firmicutes and Bacteroidetes were suggested to be important phyla for MP exposure, partially dominating further metabolite alterations. Simultaneously, MP-induced metabolic profiles were associated with energy homeostasis and bile acid, nucleotide, and carnitine metabolic pathways. The results of the mediation analysis further revealed an MP-microbiota-metabolite relationship. Our results indicate that MPs can induce gut dysbiosis and disturb metabolic dysfunction in the mouse brain and/or intestine. Integrative omics approaches have the potential to monitor MP-induced molecular responses in various organs and systematically elucidate the complex mechanisms of human health effects.

Magnetic resonance elastography of malignant tumors

Cancer biomechanical properties, including high stiffness, solid stress, and interstitial pressure, as well as altered micro-architecture, are drivers of tumorigenesis, invasiveness and resistance to treatment. Magnetic resonance elastography is an emergent non-invasive imaging method to assess the tumor mechanical properties in a spatially resolved fashion. Several MRE acquisition and reconstruction methods have been developed to assess tumors and surrounding tissues. It is increasingly recognized that the visco-elastic properties assessed with MRE are useful for characterizing malignant tumors and evaluating treatment response in various organs. Generally, malignant tumors, except brain tumors, have high stiffness and high visco-elastic ratio or fluidity. MRE transducers, acquisition sequences and reconstruction algorithms are continuously improved to increase depth penetration and spatial resolution, and limit artifacts at spatial discontinuities. Moreover, assessment of compression stiffening might provide new biomarkers of the altered physical traits of cancer. Increasing research and clinical validation will improve the efficacy of MRE for cancer characterization.

TGF-β1/SMADs signaling involved in alleviating inflammation induced by nanoparticulate titanium dioxide in BV2 cells

There are increasing safety concerns accompanying the widespread use of nanoparticulate titanium dioxide (nano-TiO2). It has been demonstrated that nano-TiO2 can cross the blood-brain barrier and enter the brain, causing damage to the nervous system, consisting mainly of neuroinflammation and neuronal apoptosis. Several studies have linked the TGF-β1/SMADs signaling to the development of inflammatory response in various organs. However, no studies have connected the induction of microglial inflammation by nano-TiO2 to this signaling. Therefore, this study aimed to investigate the role of TGF-β1/SMADs signaling in microglia inflammatory response induced by nano-TiO2. The results showed that nano-TiO2 increased the secretions of pro-inflammatory cytokines (IL-1α, IL-6, and TNF-α) and decreased the expressions of TGF-β1 and SMAD1/2/3 proteins in BV2 cells. When TGF-β1/SMADs signaling was inhibited, the inflammatory effect induced by nano-TiO2 increased, suggesting a suppressive effect of this signaling on the inflammation. In addition, exogenous TGF-β1 upregulated the expressions of TGF-β1 and SMADs1/2/3 proteins as well as decreased the secretions of pro-inflammatory cytokines (IL-1α, IL-6, and TNF-α) compared to BV2 cells treated with only nano-TiO2. Our results suggest that nano-TiO2 may inhibit the TGF-β1/SMADs signaling by suppressing the intracellular secretion of active TGF-β1, leading to microglial activation and the induction or exacerbation of inflammatory responses.

Comprehensive Cellular Dissection of the Bone Marrow Microenvironment in Primary Myelofibrosis

Primary myelofibrosis (PMF) is a severe subtype of myeloproliferative neoplasm (MPN) characterized by progressive bone marrow (BM) fibrosis and hematopoietic insufficiency, reflecting profound pathology of the BM microenvironment. However, a comprehensive understanding of the stromal cell changes that drive BM remodeling in PMF remains lacking.We performed lineage tracing and single-cell RNA sequencing (scRNA-seq) of PMF bone marrow stromal cells to comprehensively understand the maladaptive fibrosis process. PMF was induced using two established murine transplantation models: THPO overexpression (TOE) and the clinically relevant MPLW515L mutation. LepR and Gli1 are both putative markers of mesenchymal stromal cell (MSC) populations that give rise to myofibroblasts. To assess their relative contributions to BM fibrosis, we performed a head-to-head lineage tracing comparison using Lepr-Cre; tdTomato and Gli1-CreER; tdTomato mice. Our steady-state analysis in young adult animals (6-7 weeks) demonstrated that LepR- and Gli1-lineage cells occupy largely distinct areas of long bones aside from limited overlap in the metaphysis. LepR-lineage cells were distributed uniformly throughout the bone marrow whereas Gli1-lineage cells were sparse and primarily localized near the growth plate. Under PMF conditions, LepR + cells contributed to the majority of myofibroblasts (>80%) while Gli1 + cells contributed to a minority of myofibroblasts (<5%) in the central marrow. Accordingly, Gli1 knockout from either the stromal compartment or the hematopoietic compartment did not significantly alter the course of PMF development. We next performed scRNA-seq on control and PMF stromal cells from Lepr-Cre; tdTomato mice, which allowed us to retain the relevant lineage information and collect an unbiased representation of all BM cells. After excluding hematopoietic cells, three distinct stromal cell lineages (MSCs, endothelial cells, and glial cells) were apparent from the aggregate data. MSCs exclusively expressed tdTomato, prompting us to divide them into Lepr1, Lepr2, Lepr3, Lepr4, Lepr cycling, and pericyte subpopulations. Compared with controls, PMF mice had significant expansion of Lepr3, Lepr4, pericytes, and glial cells. Gene expression analysis showed that Lepr3 MSCs were osteolineage-fated cells (high Alpl, Postn, Bglap) whereas Lepr4 MSCs were enriched for matricellular genes including Timp1, Fbln2, and Sdc4, underscoring how fibrosis involves dynamic cell-matrix interactions. Importantly, as a whole, LepR-MSCs upregulated extracellular matrix proteins (e.g. Col1a1, Col3a1) and downregulated key niche factor genes (e.g. Cxcl12, Scf), consistent with reprogramming toward a myofibroblast fate that drives BM fibrosis. Concurrently, neurovascular changes manifested with endothelial cell upregulation of arteriolar-signature genes, accompanied by an expansion of pericytes and Sox10 + glial cells. Cells within the neurovascular unit regulate an array of functional responses in various organs, and these changes in PMF may coordinate processes such as angiogenesis, osteosclerosis, and hematopoietic stem cell (HSC) mobilization. Ligand-receptor interaction analysis revealed a dramatic increase in cell-cell signaling among the various stromal cell populations in PMF, with pericytes and glial cells serving as active signaling hubs. Differential intercellular information flow identified familiar fibrosis pathways such as PDGF and TGFb as well as novel pathways such as NOTCH, MIF, and GRN. Notably, Hedgehog signaling was not appreciated.In summary, we performed a comprehensive cellular dissection of the transformed BM microenvironment in PMF using rigorous cell lineage tracing and unbiased scRNA-seq. Our analysis firmly establishes LepR + MSCs as the primary reservoir for myofibroblasts in the bone marrow and provides single-cell transcriptional profiling data that enable a global understanding of complex cellular crosstalk in the PMF niche. DisclosuresNo relevant conflicts of interest to declare.

B cell migration into skin limits local inflammation

Abstract Regulatory B cells (Bregs) limit inflammatory responses in various organs. While most studies suggest that Bregs exert their anti-inflammatory functions by virtue of IL-10 production in lymphoid tissues such as spleen and lymph nodes, we found that IL-10 producing B cells reside constitutively in skin and are preferentially recruited in inflammation in an α4β1 integrin-dependent manner. To address whether Bregs suppress inflammation at the effector site (i.e. inflamed skin), we employed mice with an inducible B-cell specific deletion of α4-integrin. Selectively blocking migration of B cells into the inflamed skin led to increased localized inflammation in mouse models of psoriasis and cutaneous hypersensitivity. The data support a model in which Bregs suppress inflammation not only in lymphoid tissues but also at effector sites.

A Case of Cryoglobulinemia after Successful Hepatitis C Virus Treatment

Cryoglobulinemic vasculitis is a complex and destructive disease process that affects multiple organ systems. The pathophysiology includes formation of immune complex deposits that create an inflammatory response in various organs, yielding distinct presentations such as purpura, arthralgias, neuropathy, fever, and pulmonary vasculitis. Over 30% of cryoglobulinemic vasculitis cases present with glomerulonephritis, which carries a worse prognosis. The majority of mixed cryoglobulinemia cases are due to active infection with hepatitis C virus (HCV). Treatment of cryoglobulinemic vasculitis involves treatment of underlaying HCV, as well as high doses of immunosuppressive agents such as steroids and rituximab, often for multiple months, but with resolution of symptoms.

The immunopathology of lung fibrosis: amphiregulin-producing pathogenic memory T helper-2 cells control the airway fibrotic responses by inducing eosinophils to secrete osteopontin.

Fibrosis is defined as excessive deposition of the extracellular matrix (ECM) in the parenchyma of various organs, and sometimes leads to irreversible organ malfunction such as idiopathic pulmonary fibrosis (IPF), a fatal disorder of the lung. Chronic inflammatory stimuli induce fibrotic responses in various organs. Various immune cells, including T helper (Th) cells in the lung, protect the host from different harmful particles, including pathogenic microorganisms. However, the dysregulation of the function of these immune cells in the lung sometimes causes inflammatory diseases, such as lung fibrosis. In this review, we will introduce an outline of the cellular and molecular mechanisms underlying the pathogenic fibrotic responses in the lung. We will also introduce the concept of the "Pathogenic Th population disease induction model," in which unique subpopulations of certain Th cell subsets control the pathology of immune-mediated inflammatory diseases. Finally, we introduce our recent findings, which demonstrate that amphiregulin-producing pathogenic memory Th2 cells control airway fibrosis through the osteopontin produced by inflammatory eosinophils. The identification of this new pathogenic Th cell population supports the concept of "Pathogenic Th population disease induction model", and will provide novel strategies for treating intractable diseases, including lung fibrosis.

Impact of Seasonal Temperature Decrease and Cold Shock on the Composition of Free Amino Acids and Phosphomonoethers in Various Organs of Amur Sleeper Percottus glenii (Eleotridae)

The Amur sleeper Perccottus glenii is used as a model for investigation of free amino acids' responses in various organs to changes of temperature during the annual cycle and under a prolonged cold shock. Phosphoethanol and phosphoserine are found during seasonal decrease of temperature and at the fourth day of cold shock in the brain. Up to the beginning of winter, the pool of phosphoethanoamine increases by 94 times. That of taurine, which is in negative reciprocal relationship with phosphoethanoamine, decreases at the seasonal drop of temperature and temperature shock. In December, fourfold increase of the taurine level was found in muscles (56% of the total pool of amino acids), while eightfold in plasma (43%). The cold shock does not stimulate accumulation of taurine in plasma, muscles, and brain and only slightly increases its content in the liver. In contrast to the constantly increasing taurine content in the plasma and muscles from April to December, the pools of proteinogenic amino acids fluctuate during the annual cycle, considerably increasing after hypobiosis and at the fourth day after the cold shock. The specific decrease of the large pool of histidine in the brain by 16.7 times is found at the fourth day of the shock, while it is by 4.8 times in muscle in winter. It is supposed that phosphoethanol (in the brain) and taurine (in other organs) may be protectors in adaptation of fish to low temperatures.

Effect of Academic Stress and Its Relationship With HRV in Young 1St year MBBS Students

stress affects all the organs of the body, its effect on autonomic nervous system reflects end response of various organs. Academic stress is predominantly psychological and stress leads to several physiological responses such as increased heart rate variability through alteration in the autonomic activity that is increased sympathetic or decreased parasympathetic activity Management of stress with the aim to prevent its complication such as cardiovascular and cerebrovascular diseases, to improve the performance of student by relaxation technique forms the basis of this research. Consented 40 subjects were enrolled for the study, subjected to short term heart rate variability(HRV) recording for 5 minutes following standard protocol. The recording of the HRV was done using AD instruments eight channel polygraph where standard limb lead II recording of electrocardiogram (ECG) was done. To determine results of the heart rate variability lab chart 8 pro of AD instruments was used which selectively uses around 300 beats good interval artifact free for obtaining report of time domain and frequency domains of heart rate variability. This short-term recording of heart rate variability was carried on twice once the students were enrolled to the course before completion of one month and second time was before the starting of the second internal examination. Our study results highlighted the event of examination is highly challenging which is demonstrated by altered heart rate variability parameters. We suggest active intervention by means of continuous evaluation process to be replaced by one-time evaluation which currently is practiced.

Alterations in geometry, biomechanics, and mineral composition of juvenile rat femur induced by nonplanar PCB-155 and/or planar PCB-169.

Exposure to widespread lipophilic and bioaccumulative polychlorinated biphenyls (PCBs) induces diverse biochemical and toxicological responses in various organs, including the bone. The aim of this study was to evaluate the changes in growth rate, geometry, serum, and bone biochemical parameters and biomechanics of juvenile rat femur induced by lactational exposure to nonplanar PCB-155 and planar PCB-169 individually and in combination. Fifteen lactating Wistar rats were divided into four groups (PCB-169, PCB-155, PCB-155+169, and control), and PCBs were administered intraperitoneally at different time points after delivery. Femurs from 22-day-old offspring were analyzed by microCT, three-point bending test and inductively coupled plasma-mass spectrometry (ICP-MS) to obtain data on bone geometry, biomechanics and mineral composition. The serum levels of calcium, phosphate and alkaline phosphatase were also determined. Lactational exposure to planar PCB-169 resulted in shorter and thinner femurs, reduced endosteal and periosteal perimeters, smaller total cross-sectional and medullary areas, and lowered serum bone marker levels and calcium levels in the bone, while femur mechanical properties were not significantly altered. The changes observed in the combination exposure (PCB-155+169) group were similar to those observed in the PCB-169 group but were less pronounced. In summary, our results demonstrate that alterations in lactationally exposed offspring were primarily induced by planar PCB-169. The milder outcome in the combined group suggested that the PCB-169-mediated toxic effects on the bone might be reduced by a nonplanar PCB-155 congener. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1135-1146, 2017.

Induction of Antioxidant and Heat Shock Protein Responses During Torpor in the Gray Mouse Lemur, Microcebus murinus

A natural tolerance of various environmental stresses is typically supported by various cytoprotective mechanisms that protect macromolecules and promote extended viability. Among these are antioxidant defenses that help to limit damage from reactive oxygen species and chaperones that help to minimize protein misfolding or unfolding under stress conditions. To understand the molecular mechanisms that act to protect cells during primate torpor, the present study characterizes antioxidant and heat shock protein (HSP) responses in various organs of control (aroused) and torpid gray mouse lemurs, Microcebus murinus. Protein expression of HSP70 and HSP90α was elevated to 1.26 and 1.49 fold, respectively, in brown adipose tissue during torpor as compared with control animals, whereas HSP60 in liver of torpid animals was 1.15 fold of that in control (P<0.05). Among antioxidant enzymes, protein levels of thioredoxin 1 were elevated to 2.19 fold in white adipose tissue during torpor, whereas Cu–Zn superoxide dismutase 1 levels rose to 1.1 fold in skeletal muscle (P<0.05). Additionally, total antioxidant capacity was increased to 1.6 fold in liver during torpor (P<0.05), while remaining unchanged in the five other tissues. Overall, our data suggest that antioxidant and HSP responses are modified in a tissue-specific manner during daily torpor in gray mouse lemurs. Furthermore, our data also show that cytoprotective strategies employed during primate torpor are distinct from the strategies in rodent hibernation as reported in previous studies.

Role of Peroxisome Proliferator-Activated Receptor γ in Ocular Diseases.

Peroxisome proliferator-activated receptor γ (PPAR γ), a member of the nuclear receptor superfamily, is a ligand-activated transcription factor that plays an important role in the control of a variety of physiological processes. The last decade has witnessed an increasing interest for the role played by the agonists of PPAR γ in antiangiogenesis, antifibrosis, anti-inflammation effects and in controlling oxidative stress response in various organs. As the pathologic mechanisms of major blinding diseases, such as age-related macular degeneration (AMD), diabetic retinopathy (DR), keratitis, and optic neuropathy, often involve neoangiogenesis and inflammation- and oxidative stress-mediated cell death, evidences are accumulating on the potential benefits of PPAR γ to improve or prevent these vision threatening eye diseases. In this paper we describe what is known about the role of PPAR γ in the ocular pathophysiological processes and PPAR γ agonists as novel adjuvants in the treatment of eye diseases.

Codon optimization, expression, purification, and functional characterization of recombinant human IL-25 in Pichia pastoris

Interleukin (IL)-25 (also known as IL-17E) is a distinct member of the IL-17 cytokine family which induces IL-4, IL-5, and IL-13 expression and promotes pathogenic T helper (Th)-2 cell responses in various organs. IL-25 has been shown to have crucial role between innate and adaptive immunity and also a key component of the protection of gastrointestinal helminthes. In this study, to produce bioactive recombinant human IL-25 (rhIL-25), the cDNA of mature IL-25 was performed codon optimization based on methylotropic yeast Pichia pastoris codon bias and cloned into the expression vector pPICZαA. The recombinant vector was transformed into P. pichia strain X-33 and selected by zeocin resistance. Benchtop fermentation and simple purification strategy were established to purify the rhIL-25 with about 17 kDa molecular mass. Functional analysis showed that purified rhIL-25 specifically bond to receptor IL-17BR and induce G-CSF production in vitro. Further annexin V-FITC/PI staining assay indicated that rhIL-25 induced apoptosis in two breast cancer cells, MDA-MB-231 and HBL-100. This study provides a new strategy for the large-scale production of bioactive IL-25 for biological and therapeutic applications.

Long-Term Safety of Low-Level Laser Therapy at Different Power Densities and Single or Multiple Applications to the Bone Marrow in Mice

The purpose of this study was to determine the long-term safety effect of low-level laser therapy (LLLT) to the bone marrow (BM) in mice. LLLT has been shown to have a photobiostimulatory effect on various cellular processes and on stem cells. It was recently shown that applying LLLT to BM in rats post-myocardial infarction caused a marked reduction of scar tissue formation in the heart. Eighty-three mice were divided into five groups: control sham-treated and laser-treated at measured density of either 4, 10, 18, or 40 mW/cm(2) at the BM level. The laser was applied to the exposed flat medial part of the tibia 8 mm from the knee joint for 100 sec. Mice were monitored for 8 months and then killed, and histopathology was performed on various organs. No histological differences were observed in the liver, kidneys, brain or BM of the laser-treated mice as compared with the sham-treated, control mice. Moreover, no neoplasmic response in the tissues was observed in the laser-treated groups as compared with the control, sham-treated mice. There were no significant histopathological differences among the same organs under different laser treatment regimes in response to the BM-derived mesenchymal stem cell proliferation following LLLT to the BM. LLLT applied multiple times either at the optimal dose (which induces photobiostimulation of stem cells in the BM), or at a higher dose (such as five times the optimal dose), does not cause histopathological changes or neoplasmic response in various organs in mice, as examined over a period of 8 months.

Comparative Analysis of Transcriptional Gene Regulation Indicates Similar Physiologic Response in Mouse Tissues at Low Absorbed Doses from Intravenously Administered211At

(211)At is a promising therapeutic radionuclide because of the nearly optimal biological effectiveness of emitted α-particles. Unbound (211)At accumulates in the thyroid gland and in other vital normal tissues. However, few studies have been performed that assess the (211)At-induced normal-tissue damage in vivo. Knowledge about the extent and quality of resulting responses in various organs offers a new venue for reducing risks and side effects and increasing the overall well-being of the patient during and after therapy. Female BALB/c nude mice were injected intravenously with 0.064-42 kBq of (211)At or mock-treated, and the kidneys, liver, lungs, and spleen were excised 24 h after injection. A transcriptional gene expression analysis was performed in triplicate using RNA microarray technology. Biological processes associated with regulated transcripts were grouped into 8 main categories with 31 subcategories according to gene ontology terms for comparison of regulatory profiles. A substantial decrease in the total number of regulated transcripts was observed between 0.64 and 1.8 kBq of (211)At for all investigated tissues. Few genes were differentially regulated in each tissue at all absorbed doses. In all tissues, most of these genes showed a nonmonotonous dependence on absorbed dose. However, the direction of regulation generally remained uniform for a given gene. Few known radiation-associated genes were regulated on the transcriptional level, and their expression profile generally appeared to be dose-independent and tissue-specific. The regulatory profiles of categorized biological processes were tissue-specific and reflected the shift in regulatory intensity between 0.64 and 1.8 kBq of (211)At. The profiles revealed strongly regulated and nonregulated subcategories. The strong regulatory change observed between 0.64 and 1.8 kBq is hypothesized to result not only from low-dose effects in each tissue but also from physiologic responses to ionizing radiation-induced damage to, for example, the (211)At-accumulating thyroid gland. The presented results demonstrate the complexity of responses to radionuclides in vivo and highlight the need for further research to also consider physiology in ionizing radiation-induced responses.

Gene Responses in the Central Nervous System of Zebrafish Embryos Exposed to the Neurotoxicant Methyl Mercury

Methyl mercury (MeHg) is a neurotoxicant with adverse effects on the development of the nervous system from fish to man. Despite a detailed understanding of the molecular mechanisms by which MeHg affects cellular homeostasis, it is still not clear how MeHg causes developmental neurotoxicity. We performed here a genome-wide transcriptional analysis of MeHg-exposed zebrafish embryos and combined this with a whole-mount in situ expression analysis of 88 MeHg-affected genes. The majority of the analyzed genes showed tissue- and region-restricted responses in various organs and tissues. The genes were linked to gene ontology terms like oxidative stress, transport and cell protection. Areas even within the central nervous system (CNS) are affected differently resulting in distinct cellular stress responses. Our study revealed an unexpected heterogeneity in gene responses to MeHg exposure in different tissues and neuronal subregions, even though the known molecular action of MeHg would predict a similar burden of exposed cells. The overall structure of the developing brain of MeHg-exposed embryos appeared normal, suggesting that the mechanism leading to differentiation of the CNS is not overtly affected by exposure to MeHg. We propose that MeHg disturbs the function of the CNS by disturbing the cellular homeostasis. As these cellular stress responses comprise genes that are also involved in normal neuronal activity and learning, MeHg may affect the developing CNS in a subtle manner that manifests itself in behavioral deficits.

Pulmonary Infection with Influenza A Virus Induces Site-Specific Germinal Center and T Follicular Helper Cell Responses

Protection from influenza A virus (IAV) challenge requires switched, high affinity Abs derived from long-lived memory B cells and plasma cells. These B cell subsets are generated in germinal centers (GCs), hallmark structures of T helper cell-driven B cell immunity. A full understanding of the GC reaction after respiratory IAV infection is lacking, as is the characterization of T follicular helper (TFH) cells that support GCs. Here, GC B cell and TFH cell responses were studied in mice following pulmonary challenge with IAV. Marked GC reactions were induced in draining lymph nodes (dLNs), lung, spleen and nasal-associated lymphoid tissue (NALT), although the magnitude and kinetics of the response was site-specific. Examination of switching within GCs demonstrated IgG2+ cells to compose the largest fraction in dLNs, lung and spleen. IgA+ GC B cells were infrequent in these sites, but composed a significant subset of the switched GC population in NALT. Further experiments demonstrated splenectomized mice to withstand a lethal recall challenge, suggesting the spleen to be unnecessary for long-term protection in spite of strong GC responses in this organ. Final studies showed that TFH cell numbers were highest in dLNs and spleen, and peaked in all sites prior to the height of the GC reaction. TFH cells purified from dLNs generated IL-21 and IFNγ upon activation, although CD4+CXCR5− T effector cells produced higher levels of all cytokines. Collectively, these findings reveal respiratory IAV infection to induce strong T helper cell-driven B cell responses in various organs, with each site displaying unique attributes.

Role of the A20-TRAF6 Axis in Lipopolysaccharide-mediated Osteoclastogenesis

Bacterial lipopolysaccharide (LPS) has long been suggested as a potent inducer of bone loss in vivo despite controversial effects on osteoclast precursors. Recently, the role of the deubiquitinating protease A20 in regulating the LPS response in various organs was reported. In the present study, we investigated whether A20 is expressed in osteoclast cultures in response to RANKL or LPS and whether this protein plays a role in osteoclast formation and activation. Human peripheral blood mononuclear cells were cultured in the presence of M-CSF ± RANKL ± LPS. Although LPS induced the formation of multinucleated TRAP-positive cells expressing OSCAR, cathepsin K, and the calcitonin receptor, these cells were not capable of lacunar resorption. Release of TNF-α was noted in LPS-treated cultures, and the addition of a neutralizing anti-TNF-α antibody abrogated osteoclast formation in these cultures. A20 appeared to be a late-expressed gene in LPS-treated cultures and was associated with TRAF6 degradation and NF-κB inhibition. Silencing of A20 restored TRAF6 expression and NF-κB activation and resulted in increased bone resorption in LPS-treated cultures. A20 appeared important in the control of bone resorption and could represent a therapeutic target to treat patients with bone resorption associated with inflammatory diseases.