Activation Of Innate Immune System Research Articles

Characterization of complex, heterogeneous lipid A samples using HPLC-MS/MS technique II. Structural elucidation of non-phosphorylated lipid A by negative-ion mode tandem mass spectrometry.

Non-phosphorylated lipid A species confer reduced inflammatory potential for the bacteria. Knowledge on their chemical structure and presence in bacterial pathogens may contribute to the understanding of bacterial resistance and activation of the host innate immune system. In this study, we report the fragmentation pathways of negatively charged, non-phosphorylated lipid A species under low-energy collision-induced dissociation conditions of an electrospray ionization quadrupole time-of-flight instrument. Charge-promoted consecutive and competitive eliminations of the acyl chains and cross-ring cleavages of the sugar residues were observed. The A-type fragment ion series and the complementary X-type fragment(s) with corresponding deprotonated carboxamide(s) were diagnostic for the distribution of the primary and secondary acyl residues on the non-reducing and the reducing ends, respectively, of the non-phosphorylated lipid A backbone. Reversed-phase liquid chromatography in combination with negative-ion electrospray ionization quadrupole time-of-flight tandem mass spectrometry could provide sufficient information on the primary and secondary acyl residues of a non-phosphorylated lipid A. As a standard, the hexa-acylated ion at m/z 1636 with the Escherichia coli-type acyl distribution (from E. coli O111) was used. The method was tested and refined with the analysis of other non-phosphorylated hexa- and several hepta-, penta-, and tetra-acylated lipid A species detected in crude lipid A fractions from E. coli O111 and Proteus morganii O34 bacteria. Copyright © 2016 John Wiley & Sons, Ltd.

New insights into sickle cell disease: mechanisms and investigational therapies.

Sickle cell disease (SCD) afflicts millions worldwide. The simplicity of its single nucleotide mutation belies the biological and psychosocial complexity of the disease. Despite only a single approved drug specifically for the treatment of SCD, new findings reviewed from 2015 provide the direction forward. The last year has provided a wealth of support for mechanisms affecting the red cell, hemolysis and vasculopathy, the innate immune system activation, blood cell and endothelial adhesiveness, central sensitization to pain, and chronic brain injury. The evidence supporting expanded use of hydroxyurea continues to mount. Many promising therapies are reaching clinical trial, including curative therapies, with more on the horizon. Evidence is compelling that the use of hydroxyurea must be expanded by clinicians to gain the full pleiotropic benefits of this approved drug. Clinicians must become aware that severe acute and chronic pain has a biological and neurologic basis, and the understanding of this basis is growing. Researchers are testing investigational therapies at an unprecedented pace in SCD, and partnership between patients, researchers, and the private sector provides the most rapid and productive way forward.

Alcohol resistance in Drosophila is modulated by the Toll innate immune pathway.

A growing body of evidence has shown that alcohol alters the activity of the innate immune system and that changes in innate immune system activity can influence alcohol-related behaviors. Here, we show that the Toll innate immune signaling pathway modulates the level of alcohol resistance in Drosophila. In humans, a low level of response to alcohol is correlated with increased risk of developing an alcohol use disorder. The Toll signaling pathway was originally discovered in, and has been extensively studied in Drosophila. The Toll pathway is a major regulator of innate immunity in Drosophila, and mammalian Toll-like receptor signaling has been implicated in alcohol responses. Here, we use Drosophila-specific genetic tools to test eight genes in the Toll signaling pathway for effects on the level of response to ethanol. We show that increasing the activity of the pathway increases ethanol resistance whereas decreasing the pathway activity reduces ethanol resistance. Furthermore, we show that gene products known to be outputs of innate immune signaling are rapidly induced following ethanol exposure. The interaction between the Toll signaling pathway and ethanol is rooted in the natural history of Drosophila melanogaster.

High‐Fat Diet‐Induced Obesity Suppresses Adaptive Thermogenesis via Toll‐Like Receptor (TLR) 4‐Mediated Endoplasmic Reticulum Stress

Adaptive thermogenesis is a cellular process that dissipates energy as heat, thus defending against obesity, in response to various activators such as cold. Obese subjects are less responsive to thermogenic signaling cues compared to lean subjects. Elevated levels of metabolic endotoxemia and circulating free fatty acids associated with obesity induce innate immune system and TLR4 activation, leading to the development of metabolic disorders. However, whether TLR4 activation plays a role in the adaptive thermogenesis impairment observed in obesity has not been investigated. In this study, we hypothesized that TLR4 activation in a high‐fat (HF) diet‐induced obesity model impairs adaptive thermogenesis. To test this hypothesis, C57BL/6 mice were fed either a low‐fat (LF) or HF diet for 12 weeks, followed by cold acclimation. HF diet‐mediated TLR4 activation concurred with a significant decrease in adaptive thermogenesis, brown‐specific markers, and mitochondrial‐specific markers in subcutaneous white adipose tissue (WAT). To verify the role of TLR4 in WAT browning, chronic low‐dose LPS was administrated to wild type and TLR4 knockout mice. LPS‐injected wild type mice were immune to both cold‐induced WAT browning and β3‐adrenergic receptor agonist (CL‐316,243)‐induced WAT browning, whereas TLR4 knockout mice were able to arouse thermogenesis. Chronic TLR4 activation in our mice resulted in ROS production and ER stress elevation. To understand the molecular link between TLR4 and ER stress in thermogenesis attenuation, ER stress was inactivated by either genetic deletion of CHOP or intraperitoneal injection of a chemical chaperone (PBA). Blunting ER stress protected the mice from TLR4‐induced mitochondrial degradation and rescued WAT browning. Taken together, our results indicate that TLR4 is a pivotal player in thermogenesis impairment observed in obesity. It mediates ROS production and ER stress activation, leading to mitochondrial degradation and WAT browning inhibition. In this study, we identified a novel TLR4/ER stress signaling axis associated with antagonizing WAT browning. Targeting this TLR4/ER stress axis might be efficacious in preventing defective thermogenesis observed in obesity.Support or Funding InformationNIH 1P20GM104320

Biomarkers in the Management of Difficult Asthma

Difficult asthma is a heterogeneous disease of the airways including various types of bronchial inflammation and various degrees of airway remodeling. Therapeutic response of severe asthmatics can be predicted by the use of biomarkers of Type2-high or Type2-low inflammation. Based on sputum cell analysis, four inflammatory phenotypes have been described. As induced sputum is time-consuming and expensive technique, surrogate biomarkers are useful in clinical practice.Eosinophilic phenotype is likely to reflect ongoing adaptive immunity in response to allergen. Several biomarkers of eosinophilic asthma are easily available in clinical practice (blood eosinophils, serum IgE, exhaled nitric oxyde, serum periostin). Neutrophilic asthma is thought to reflect innate immune system activation in response to pollutants or infectious agents while paucigranulocytic asthma is thought to be not inflammatory and characterized by smooth muscle dysfunction. We currently lack of user-friendly biomarkers of neutrophilic asthma and airway remodeling.In this review, we summarize the biomarkers available for the management of difficult asthma.

Periodic Fever, Aphthous Stomatitis, Pharyngitis, and Cervical Adenitis (PFAPA) Syndrome: a Review of the Pathogenesis.

PFAPA syndrome represents the most common cause of recurrent fever in children in European populations, and it is characterized by recurrent episodes of high fever, pharyngitis, cervical adenitis, and aphthous stomatitis. Many possible causative factors have been explored so far, including infectious agents, immunologic mechanisms and genetic predisposition, but the exact etiology remains unclear. Recent findings demonstrate a dysregulation of different components of innate immunity during PFAPA flares, such as monocytes, neutrophils, complement, and pro-inflammatory cytokines, especially IL-1β, suggesting an inflammasome-mediated innate immune system activation and supporting the hypothesis of an autoinflammatory disease. Moreover, in contrast with previous considerations, the strong familial clustering suggests a potential genetic origin rather than a sporadic disease. In addition, the presence of variants in inflammasome-related genes, mostly in NLRP3 and MEFV, suggests a possible role of inflammasome-composing genes in PFAPA pathogenesis. However, none of these variants seem to be relevant, alone, to its etiology, indicating a high genetic heterogeneity as well as an oligogenic or polygenic genetic background.

Vascular-directed responses of microglia produced by methamphetamine exposure: indirect evidence that microglia are involved in vascular repair?

BackgroundBrain microglial activations and damage responses are most commonly associated with neurodegeneration or systemic innate immune system activation. Here, we used histological methods to focus on microglial responses that are directed towards brain vasculature, previously undescribed, after a neurotoxic exposure to methamphetamine.MethodsMale rats were given doses of methamphetamine that produce pronounced hyperthermia, hypertension, and toxicity. Identification of microglia and microglia-like cells (pericytes and possibly perivascular cells) was done using immunoreactivity to allograft inflammatory factor 1 (Aif1 a.k.a Iba1) and alpha M integrin (Itgam a.k.a. Cd11b) while vasculature endothelium was identified using rat endothelial cell antigen 1 (RECA-1). Regions of neuronal, axonal, and nerve terminal degeneration were determined using Fluoro-Jade C.ResultsDual labeling of vasculature (RECA-1) and microglia (Iba1) showed a strong association of hypertrophied cells surrounding and juxtaposed to vasculature in the septum, medial dorsal hippocampus, piriform cortex, and thalamus. The Iba1 labeling was more pronounced in the cell body while Cd11b more so in the processes of activated microglia. These regions have been previously identified to have vascular leakage after neurotoxic methamphetamine exposure. Dual labeling with Fluoro-Jade C and Iba1 indicated that there was minimal or no evidence of neuronal damage in the septum and hippocampus where many hypertrophied Iba1-labeled cells were found to be associated with vasculature. Although microglial activation around the prominent neurodegeneration was found in the thalamus, there were also many examples of activated microglia associated with vasculature.ConclusionsThe data implicate microglia, and possibly related cell types, in playing a major role in responding to methamphetamine-induced vascular damage, and possibly repair, in the absence of neurodegeneration. Identifying brain regions with hypertrophied/activated microglial-like cells associated with vasculature has the potential for identifying regions of more subtle examples of vascular damage and BBB compromise.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-016-0526-6) contains supplementary material, which is available to authorized users.

Maternal immune activation alters glutamic acid decarboxylase-67 expression in the brains of adult rat offspring

Activation of the maternal innate immune system, termed “maternal immune activation” (MIA), represents a common environmental risk factor for schizophrenia. Whereas evidence suggests dysregulation of GABA systems may underlie the pathophysiology of schizophrenia, a role for MIA in alteration of GABAergic systems is less clear. Here, pregnant rats received either the viral mimetic polyriboinosinic–polyribocytidilic acid or vehicle injection on gestational day 14. Glutamic acid decarboxylase-67 (GAD67) mRNA expression was examined in male offspring at postnatal day (P)14, P30 and P60. At P60, GAD67 mRNA was elevated in hippocampus and thalamus and decreased in prefrontal cortex of MIA offspring. MIA-induced alterations in GAD expression could contribute to the pathophysiology of schizophrenia.

Alzheimer's disease: a novel hypothesis for the development and the subsequent role of beta amyloid

Spirochetes, biofilms, innate immune system activity have all been recently found in the brains of Alzheimer's disease patients. The mechanism and actions of those entities in producing the disease were postulated in those studies. The production and role of beta amyloid were not included in the discussion; we hypothesize herein how the development of that molecule occurs as a result of the Toll-like receptor 2 activation leading not only to TNFα, but also NFκB which themselves have been previously shown to induce the secretases necessary to cleave the amyloid precursor protein. This leads directly to beta amyloid. The beta amyloid (Aβ) has been shown to be antimicrobial, and its presence on and around the hippocampal plaques (the pathological hallmark of Alzheimer's disease) has been demonstrated. It becomes apparent that the Aβ tries to kill the spirochetes but cannot penetrate the biofilm. Its buildup then interrupts and destroys the neurocircuitry of the brains.

Arteriosclerosis: The Novel Finding of Biofilms and Innate Immune System Activity within the Plaques

Atherosclerosis (AS) is a chronic disorder characterized by the formation and progression of plaques within arteries. Various microbes, most notably periodontal organisms, have been identified in plaques both epidemiologically and microbiologically, and have been deemed possible contributors to the disease. In this work, we have queried whether microbes acted similarly in AS, when compared to other chronic diseases such as atopic dermatitis, psoriasis, and Alzheimer’s disease, by making biofilms to protect themselves and evade the immune system. In those diseases, the microbes created biofilms that activated the innate immune system reactant Toll-like receptor 2 (TLR2). We examined 12 endarterectomy specimens using probes similar to those used in our previous examinations of the above diseases. Specifically, we stained the pathology specimens with hematoxylin and eosin (H+E), and periodic acid Schiff (PAS); the PAS stain would reveal the extracellular polysaccharides that forms the mass of the biofilm. Congo red, which stains the amyloid that forms the infrastructure of biofilms, was also performed. Immunostaining with CD 282 was performed on each specimen for evaluation of TLR 2. Twelve of twelve atherosclerotic plaques showed the presence of biofilms and activation of TLR 2; this is entirely similar to our findings in atopic dermatitis, psoriasis and Alzheimer’s disease. The TLR 2 seen in the specimens suggests that biofilms in atherosclerotic plaques may contribute to the progression of the disease as a result of their ability to contribute to chronic inflammation and continued immune system activation. Lipids have long been considered to be the major focus of atherosclerosis, but our recent work suggests that biofilms, due to their ability to induce a chronic inflammatory state, may be another determinant in the progression of atherosclerosis. In the future, we hope to characterize the microbes-with an initial focus on periodontal microbes because of the calcification in the plaques-that directly contribute to biofilm formation and propagation.

Abstract A191: Augmenting the therapeutic efficacy of oncolytic LCMV-GP pseudotyped vesicular stomatitis virus via modulation of the innate immune system

Abstract Introduction: Vesicular stomatitis virus (VSV) is a promising oncolytic virus candidate due to its fast mode of action, high titer production, absence of pre-existing anti-VSV immunity and broad tumor tropism. However, potential neurotoxicity of wild-type VSV and a rapid induction of neutralizing antibodies have been a hindrance for further clinical advancement. Our group previously reported that pseudotyping VSV with the LCMV glycoprotein (VSV-GP) results in complete abrogation of neurotoxicity and the absence of neutralizing antibody induction [1]. Here we addressed to what extent the innate immune response to VSV-GP limits its oncolytic efficacy and analyze means to counter these inhibiting factors. Methods: MTT cell viability and TCID50 viral replication assays were used to quantify oncolytic activity in vitro. VSV-GP oncolytic efficiency was also tested in vivo using both xenograft and syngeneic mouse models. Results: VSV-GP exhibited high oncolytic efficiency in vitro, achieving 80-100% killing at 48-72 h post infection in most ovarian, melanoma, and lung cancer cell lines. Further analysis of resistant cell lines showed that these cells were able to mount an interferon (IFN-I) induced antiviral response. VSV-GP efficacy was also tested for ovarian cancer in vivo using s.c xenograft models and in an orthotopic model. Intratumoral injection of VSV-GP into ovarian s.c. xenografts led to tumor remission in all animals. Relapse was observed and relapsing tumors remained sensitive for successive VSV-GP treatment. Significantly prolonged survival was also observed in an ovarian cancer orthotopic model using IVIS in vivo imaging. Oncolytic potency of VSV-GP was enhanced with combination treatment with Jak1/2 inhibitors. Conclusion: These results confirm that LCMV GP-pseudotyped VSV exhibits a highly beneficial toxicity and efficacy profile. However, tumors escaping complete oncolyse via innate immune system activation require coapplication of targeted immune modulators. Reference: [1] - Muik, A. et al. Re-engineering Vesicular Stomatitis Virus to Abrogate Neurotoxicity, Circumvent Humoral Immunity, and Enhance Oncolytic Potency. Cancer Res 74, 3567-3578, (2014). Citation Format: Carles Rodriguez Urbiola, Catherine Dold, Janine Kimpel, Christian Marth, Frederic Santer, Zoran Culig, Alexander Muik, Tanja Knapp, Ira Winkler, Guido Wollmann, Dorothee Von Laer, Patrik Erlmann. Augmenting the therapeutic efficacy of oncolytic LCMV-GP pseudotyped vesicular stomatitis virus via modulation of the innate immune system. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A191.

ADAR1, inosine and the immune sensing system: distinguishing self from non-self.

The conversion of genomically encoded adenosine to inosine in dsRNA is termed as A-to-I RNA editing. This process is catalyzed by two of the three mammalian ADAR proteins (ADAR1 and ADAR2) both of which have essential functions for normal organismal homeostasis. The phenotype of ADAR2 deficiency can be primarily ascribed to a lack of site-selective editing of a single transcript in the brain. In contrast, the biology and substrates responsible for the Adar1(-/-) phenotype have remained more elusive. Several recent studies have identified that a feature of absence or reductions of ADAR1 activity, conserved across human and mouse models, is a profound activation of interferon-stimulated gene signatures and innate immune responses. Further analysis of this observation has lead to the conclusion that editing by ADAR1 is required to prevent activation of the cytosolic innate immune system, primarily focused on the dsRNA sensor MDA5 and leading to downstream signaling via MAVS. The delineation of this mechanism places ADAR1 at the interface between the cells ability to differentiate self- from non-self dsRNA. Based on MDA5 dsRNA recognition requisites, the mechanism indicates that the type of dsRNA must fulfil a particular structural characteristic, rather than a sequence-specific requirement. While additional studies are required to molecularly verify the genetic model, the observations to date collectively identify A-to-I editing by ADAR1 as a key modifier of the cellular response to endogenous dsRNA.

A Microfluidic Model of Microvascular Inflammation: Characterization and Testing of Endothelial-Targeted Therapeutics

* These authors contributed equally to this workThe microvasculature plays a key role in the pathogenesis of sepsis, ARDS, multiorgan dysfunction, and a variety of other human diseases characterized by a pro-coagulant, pro-adhesive endothelial phenotype. The complex interactions that occur at the interface of blood and activated endothelium are difficult to resolve in animal models and challenging to recreate in cell culture systems. While individual processes - e.g., leukocyte adhesion and transmigration - have been extensively studied, development of a well-characterized model integrating the full range of pathogenic processes (coagulation, barrier dysfunction, innate immune system activation, etc.) remains an important unmet goal, which could both elucidate mechanisms of disease and aid in the design and testing of putative therapeutics. To this end, we sought to model an inflamed vascular segment using a Fluxion Bioflux system. 3-dimensional confluent endothelial cell (EC) monolayers were established within fibronectin-coated laminar flow chambers. ECs were flow adapted, activated with TNFa, and then perfused with whole blood (WB) at a variety of shear stresses. Real time fluorescence microscopy allowed continuous monitoring of fibrin deposition and leukocyte and platelet adhesion. The multi-channel format, which allows simultaneous testing of multiple conditions with replicates, proved to be a critical asset, given substantial day-to-day variability. Both fibrin deposition and adhesive events showed dependence on dose (1 vs. 10 ng/mL) and duration (4 vs. 6hr) of TNF activation. Confocal microscopy revealed TNF-dependent, increases in EC expression of ICAM-1, VCAM-1, and tissue factor (TF), as well as suppression of endothelial thrombomodulin (TM). Activation of the coagulation system was completely abrogated by treatment of the EC monolayer with a TF-inhibiting antibody, suggesting a primary role for the extrinsic pathway. Hirudin also limited fibrin deposition when added to whole blood prior to perfusion, although "breakthrough clotting" was seen in some channels. Finally, the role of endothelial TM was investigated in several ways, including by the use of a blocking antibody, which prevents thrombin binding. Treatment of ECs with this antibody markedly increased fibrin deposition, whereas TM/R6.5 scFv, a novel targeted fusion protein therapeutic, which anchors recombinant TM to endothelial ICAM-1, inhibited fibrin deposition upon subsequent infusion of WB. Neither soluble TM (sTM) nor anti-ICAM-1 R6.5 scFv alone had any effect on coagulation when infused in this setting (i.e., prior to WB) and even addition of a large excess of sTM to whole blood was less effective in reducing TNF-dependent fibrin deposition than pre-treatment with the ICAM-targeted TM fusion protein, indicating potential importance of precision drug delivery on the microscale. In summary, the described microfluidic, "endothelialized", whole blood model of an inflamed microvessel may prove useful in interrogating specific aspects of a variety of vascular pathologies and in devising and improving therapeutic interventions. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Antiviral Protection via RdRP-Mediated Stable Activation of Innate Immunity.

For many emerging and re-emerging infectious diseases, definitive solutions via sterilizing adaptive immunity may require years or decades to develop, if they are even possible. The innate immune system offers alternative mechanisms that do not require antigen-specific recognition or a priori knowledge of the causative agent. However, it is unclear whether effective stable innate immune system activation can be achieved without triggering harmful autoimmunity or other chronic inflammatory sequelae. Here, we show that transgenic expression of a picornavirus RNA-dependent RNA polymerase (RdRP), in the absence of other viral proteins, can profoundly reconfigure mammalian innate antiviral immunity by exposing the normally membrane-sequestered RdRP activity to sustained innate immune detection. RdRP-transgenic mice have life-long, quantitatively dramatic upregulation of 80 interferon-stimulated genes (ISGs) and show profound resistance to normally lethal viral challenge. Multiple crosses with defined knockout mice (Rag1, Mda5, Mavs, Ifnar1, Ifngr1, and Tlr3) established that the mechanism operates via MDA5 and MAVS and is fully independent of the adaptive immune system. Human cell models recapitulated the key features with striking fidelity, with the RdRP inducing an analogous ISG network and a strict block to HIV-1 infection. This RdRP-mediated antiviral mechanism does not depend on secondary structure within the RdRP mRNA but operates at the protein level and requires RdRP catalysis. Importantly, despite lifelong massive ISG elevations, RdRP mice are entirely healthy, with normal longevity. Our data reveal that a powerfully augmented MDA5-mediated activation state can be a well-tolerated mammalian innate immune system configuration. These results provide a foundation for augmenting innate immunity to achieve broad-spectrum antiviral protection.

Innate immune system activation by viral RNA: How to predict it?

The immune system is able to identify foreign pathogens via different pathways. In the case of viral infection, recognition of the viral RNA is a crucial step, and many efforts have been made to understand which features of viral RNA are detected by the immune system. The biased viral RNA composition, measured as host–virus nucleotidic divergence, or CpG enrichment, has been proposed as salient signal. Peculiar structural features of these RNA could also be related to the immune system activation. Here, we gather multiple datasets and proceed to a meta-analysis to uncover the best predictors of immune system activation by viral RNA. “A” nucleotide content and Minimum Folding Energy are good predictors, and are more easily generalized than more complex indicators suggested previously. As RNA composition and structure are highly correlated, we suggest further experiments on synthetic sequences to identify the viral RNA sensing mechanisms by immune system receptors.

High-volume plasma exchange in patients with acute liver failure: an open randomized controlled trial

The mortality of patients with acute liver failure (ALF) remains high, despite advances in supportive management and bridging to liver transplantation. Disappointingly, prospective trials of extracorporeal support with albumin dialysis, superflux dialyzers in series with absorption columns, and bioartificial devices containing hepatocytes have not demonstrated a significant survival advantage. In the era before liver failure became an established treatment for ALF, there were case series reports of plasma exchange improving cardiovascular stability, extending survival, to allow liver transplantation and increasing overall survival. Larsen and colleagues now report on a randomized, three-center, prospective controlled trial of plasma exchange in a wide range of patients presenting with ALF who had grade 2 encephalopathy or greater. This trial took 12 years to recruit 183 patients. Although there have been advances in supportive care over time, the investigators reported no differences in outcomes when comparing earlier and later recruitment. Compared with many previous studies, the patients were randomized to high-volume plasma exchange, 15% of ideal body weight or around 10–12 liters of fresh-frozen plasma per session for 3 consecutive days. Not all patients received 3 days of treatment because of early death or transplantation. Some patients started plasma exchange therapy shorty after intensive care admission, whereas others had treatment initiation delayed for more than 48 hours. Despite these confounders, the authors reported not only improved cardiovascular stability but also improved patient survival, particularly for those patients who did not receive transplants, and in particular for patients with severe illness who qualified for transplant listing but could not be listed because of contraindications for transplantation. The question arises of why higher-volume plasma exchange should be beneficial. The authors examined removal of markers of cell death (damage-associated molecular pattern molecules) and innate immune system activity in a small cohort of patients, but it remains unclear whether the benefits of high-volume plasma exchange are due to the removal of toxins or the addition of fresh-frozen plasma. Thus, this study will promote further investigation of the effects of plasma exchange. Andrew Davenport

A requirement of serotonergic p38α mitogen-activated protein kinase for peripheral immune system activation of CNS serotonin uptake and serotonin-linked behaviors.

Alterations in central serotonin (5-hydroxytryptamine, 5-HT) neurotransmission and peripheral immune activation have been linked to multiple neuropsychiatric disorders, including depression, schizophrenia and autism. The antidepressant-sensitive 5-HT transporter (SERT, SLC6A4), a critical determinant of synaptic 5-HT inactivation, can be regulated by pro-inflammatory cytokine signaling. Systemic innate immune system activation via intraperitoneal lipopolysaccharide (LPS) injection rapidly elevates brain SERT activity and 5-HT clearance. Moreover, the pro-inflammatory cytokine interleukin (IL)-1β rapidly stimulates SERT activity in raphe nerve terminal preparations ex vivo, effects that are attenuated by pharmacological p38 MAPK inhibition. To establish a role of serotonergic p38α MAPK signaling in LPS/IL-1β-induced SERT regulation and attendant behavioral responses, we pursued studies in mice that afford conditional elimination of p38α MAPK in 5-HT neurons (p38α5HT−). We found p38α5HT− and control (p38α5HT+) littermates to be indistinguishable in viability and growth and to express equivalent levels of SERT protein and synaptosomal 5-HT transport activity. Consistent with pharmacological studies, however, IL-1β fails to increase SERT activity in midbrain synaptosomes prepared from p38α5HT− animals. Moreover, although LPS elevated plasma corticosterone and central/peripheral pro-inflammatory cytokines in p38α5HT− animals, elevations in midbrain SERT activity were absent nor were changes in depressive and anxiety-like behaviors observed. Our studies support an obligate role of p38α MAPK signaling in 5-HT neurons for the translation of immune activation to SERT regulation and 5-HT-modulated behaviors.

Chronic Endotoxemia in Subjects with Type-1 Diabetes Is Seen Much before the Onset of Microvascular Complications.

BackgroundLipopolysaccharide (LPS)/Endotoxin is hypothesized to play an important role in chronic inflammation associated with Type-1 diabetes (T1DM) and its complications. Endotoxin core antibodies (EndoCAb), LPS binding protein (LBP) and soluble CD14 (sCD14) act as modulators of LPS induced activation of innate immune system in vivo. For the present study we estimated the levels of LPS and its translocation markers in T1DM subjects with and without microvascular complications (MVC) and correlate them with clinical parameters of T1DM and serum inflammatory cytokine levels (TNF-α, IL-6, IL-1β and GM-CSF).MethodsA total of 197 subjects (64 normal glucose tolerance (NGT) subjects, 97 T1DM subjects without MVC and 36 with MVC) were included in this study and the levels of serum LPS, its translocation markers and cytokines measured by immunoassays.ResultsCompared to NGT, T1DM subjects (both with and without MVC) had significantly higher levels of LPS, reduced levels of LBP and EndoCAb along with significant increase in the levels of IL-1β, IL-6, TNF-α and GM-CSF (p<0.05). No significant change was seen in the levels of these biomarkers between T1DM subjects with and without MVC.ConclusionsDecreased levels of EndoCAb and LBP suggest sustained endotoxin activity in T1DM subjects even before the onset of microvascular complications.

Evasion of the Innate Immune Type I Interferon System by Monkeypox Virus.

The vaccinia virus (VACV) E3 protein has been shown to be important for blocking activation of the cellular innate immune system and allowing viral replication to occur unhindered. Mutation or deletion of E3L severely affects viral host range and pathogenesis. While the monkeypox virus (MPXV) genome encodes a homologue of the VACV E3 protein, encoded by the F3L gene, the MPXV gene is predicted to encode a protein with a truncation of 37 N-terminal amino acids. VACV with a genome encoding a similarly truncated E3L protein (VACV-E3LΔ37N) has been shown to be attenuated in mouse models, and infection with VACV-E3LΔ37N has been shown to lead to activation of the host antiviral protein kinase R pathway. In this report, we present data demonstrating that, despite containing a truncated E3 homologue, MPXV phenotypically resembles a wild-type (wt) VACV rather than VACV-E3LΔ37N. Thus, MPXV appears to contain a gene or genes that can suppress the phenotypes associated with an N-terminal truncation in E3. The suppression maps to sequences outside F3L, suggesting that the suppression is extragenic in nature. Thus, MPXV appears to have evolved mechanisms to minimize the effects of partial inactivation of its E3 homologue. Poxviruses have evolved to have many mechanisms to evade host antiviral innate immunity; these mechanisms may allow these viruses to cause disease. Within the family of poxviruses, variola virus (which causes smallpox) is the most pathogenic, while monkeypox virus is intermediate in pathogenicity between vaccinia virus and variola virus. Understanding the mechanisms of monkeypox virus innate immune evasion will help us to understand the evolution of poxvirus innate immune evasion capabilities, providing a better understanding of how poxviruses cause disease.

Prevention of Defective Placentation and Pregnancy Loss by Blocking Innate Immune Pathways in a Syngeneic Model of Placental Insufficiency.

Defective placentation and subsequent placental insufficiency lead to maternal and fetal adverse pregnancy outcome, but their pathologic mechanisms are unclear, and treatment remains elusive. The mildly hypertensive BPH/5 mouse recapitulates many features of human adverse pregnancy outcome, with pregnancies characterized by fetal loss, growth restriction, abnormal placental development, and defects in maternal decidual arteries. Using this model, we show that recruitment of neutrophils triggered by complement activation at the maternal/fetal interface leads to elevation in local TNF-α levels, reduction of the essential angiogenic factor vascular endothelial growth factor, and, ultimately, abnormal placentation and fetal death. Blockade of complement with inhibitors specifically targeted to sites of complement activation, depletion of neutrophils, or blockade of TNF-α improves spiral artery remodeling and rescues pregnancies. These data underscore the importance of innate immune system activation in the pathogenesis of placental insufficiency and identify novel methods for treatment of pregnancy loss mediated by abnormal placentation.