Sensing microorganisms in the gut triggers the immune response in Eisenia andrei earthworms

The tube-within-tube body plan of earthworms is appropriate for studying the interactions of microorganisms with the immune system of body cavities such as the digestive tract and coelom. This study aims to describe the immune response on the molecular and cellular level in the coelomic cavity and the gut of the earthworm Eisenia andrei after experimental microbial challenge by administering two bacterial strains (Escherichia coli and Bacillus subtilis) or yeast Saccharomyces cerevisiae to the environment. The changes in mRNA levels of defense molecules (pattern recognition receptor CCF, lysozyme, fetidin/lysenins) in the coelomocytes and gut tissue were determined by quantitative PCR. The immune response at a cellular level was captured in histological sections, and the expression of CCF was localized using in situ hybridization. Coelomocytes respond to the presence of bacteria in the coelomic cavity by increasing the mRNA levels of defense molecules, especially CCF. The immune response in gut tissue is less affected by microbial stimulation because the epithelial cells of gut exhibit basically strong mRNA synthesis of ccf as a defense against the continuous microbial load in the gut lumen. The cellular immune response is mediated by coelomocytes released from the mesenchymal lining of the coelomic cavity. These combined immune mechanisms are necessary for the survival of earthworms in the microbially rich environment of soil.     

Genome-wide miRNA screening reveals miR-310 family members negatively regulate the immune response in Drosophila melanogaster via co-targeting Drosomycin

Although innate immunity mediated by Toll signaling has been extensively studied in Drosophila melanogaster, the role of miRNAs in regulating the Toll-mediated immune response remains largely unknown. In this study, following Gram-positive bacterial challenge, we identified 93 differentially expressed miRNAs via genome-wide miRNA screening. These miRNAs were regarded as immune response related (IRR). Eight miRNAs were confirmed to be involved in the Toll-mediated immune response upon Gram-positive bacterial infection through genetic screening of 41 UAS-miRNA lines covering 60 miRNAs of the 93 IRR miRNAs. Interestingly, four out of these eight miRNAs, miR-310, miR-311, miR-312 and miR-313, are clustered miRNAs and belong to the miR-310 family. These miR-310 family members were shown to target and regulate the expression of Drosomycin, an antimicrobial peptide produced by Toll signaling. Taken together, our study implies important regulatory roles of miRNAs in the Toll-mediated innate immune response of Drosophila upon Gram-positive bacterial infection.     

Myasthenia gravis: A comprehensive review of immune dysregulation and etiological mechanisms

Autoimmune myasthenia gravis (MG) is characterized by muscle weakness caused by antibodies directed against proteins of the neuromuscular junction. The main antigenic target is the acetylcholine receptor (AChR), but the muscle Specific Kinase (MuSK) and the low-density lipoprotein receptor-related protein (LRP4) are also targets. This review summarizes the clinical and biological data available for different subgroups of patients, who are classified according to antigenic target, age of onset, and observed thymic abnormalities, such as follicular hyperplasia or thymoma.Here, we analyze in detail the role of the thymus in the physiopathology of MG and propose an explanation for the development of the thymic follicular hyperplasia that is commonly observed in young female patients with anti-AChR antibodies. The influence of the pro-inflammatory environment is discussed, particularly the role of TNF-α and Th17-related cytokines, which could explain the escape of thymic T cells from regulation and the chronic inflammation in the MG thymus. Together with this immune dysregulation, active angiogenic processes and the upregulation of chemokines could promote thymic follicular hyperplasia.MG is a multifactorial disease, and we review the etiological mechanisms that could lead to its onset. Recent global genetic analyses have highlighted potential susceptibility genes. In addition, miRNAs, which play a crucial role in immune function, have been implicated in MG by recent studies. We also discuss the role of sex hormones and the influence of environmental factors, such as the viral hypothesis. This hypothesis is supported by reports that type I interferon and molecules mimicking viral infection can induce thymic changes similar to those observed in MG patients with anti-AChR antibodies.     

Nuclear organization of some immunohistochemically identifiable neural systems in two species of the Euarchontoglires: A Lagomorph,Lepus capensis,and a Scandentia,Tupaia belangeri

The present study describes the organization of the nuclei of the cholinergic, catecholaminergic, serotonergic and orexinergic systems in the brains of two members of Euarchontoglires, Lepus capensis and Tupaia belangeri. The aim of the present study was to investigate the nuclear complement of these neural systems in comparison to previous studies on Euarchontoglires and generally with other mammalian species. Brains were coronally sectioned and immunohistochemically stained with antibodies against choline acetyltransferase, tyrosine hydroxylase, serotonin and orexin-A. The majority of nuclei revealed in the current study were similar between the species investigated and to mammals generally, but certain differences in the nuclear complement highlight potential phylogenetic interrelationships within the Euarchontoglires and across mammals. In the northern tree shrew the nucleus of the trapezoid body contained neurons immunoreactive to the choline acetyltransferase antibody with some of these neurons extending into the lamellae within the superior olivary nuclear complex (SON). The cholinergic nature of the neurons of this nucleus, and the extension of cholinergic neurons into the SON, has not been noted in any mammal studied to date. In addition, cholinergic neurons forming the medullary tegmental field were also present in the northern tree shrew. Regarding the catecholaminergic system, the cape hare presented with the rodent specific rostral dorsal midline medullary nucleus (C3), and the northern tree shrew lacked both the ventral and dorsal divisions of the anterior hypothalamic group (A15v and A15d). Both species were lacking the primate/megachiropteran specific compact portion of the locus coeruleus complex (A6c). The nuclei of the serotonergic and orexinergic systems of both species were similar to those seen across most Eutherian mammals. Our results lend support to the monophyly of the Glires, and more broadly suggest that the megachiropterans are more closely related to the primates than are any other members of Euarchontoglires studied to date.     

The role of aquaporin-1 in idiopathic and drug-induced intracranial hypertension

Idiopathic intracranial hypertension is a common disorder affecting mainly healthy, young, overweight women. The pathogenesis of this condition is unknown, but it has been shown to follow treatment with several compounds including corticosteroids and vitamin A derivatives. This paper will offer a novel hypothesis and insight on the pathogenesis of drug induced intracranial hypertension following a review and analysis of the literature. Both corticosteroids and vitamin A derivatives have been shown to upregulate the expression of aquaporin 1, a water channel protein. Aquaporin 1 is widely distributed in the human brain and is associated with water secretion into the subarachnoid space. Aquaporin 1 was also shown to participate in the regulation of weight. Agents used for treating idiopathic intracranial hypertension reduce aquaporin 1 expression. Based on these observations, we propose that aquaporin 1 has a pathogenetic role in drug induced idiopathic intracranial hypertension. Over expression of this gene causes increased intracranial pressure, and downregulation reduces pressure and alleviates the symptomatology and complications of idiopathic intracranial hypertension.     

Disturbed sleep in bipolar disorder is related to an elevation of IL-6 in peripheral monocytes

Bipolar disorder is a severe psychiatric disorder that is associated with persistent changes in the quality, duration and architecture of sleep. Currently there is no unifying hypothesis explaining the alterations in sleep observable in patients with bipolar disorder and management is often difficult though vital.Sleep is modified by various cytokines including IL-6. Elevated levels of IL-6 are associated with a poorer quality of sleep and changes in the architecture of sleep similar to those observed in bipolar disorder. Therapeutic administration of Interferon causes elevations of intrathecal IL-6 concentrations and appears to provoke a deteriorating quality of sleep. The blockade of IL-6 with tocilizumab in rheumatoid arthritis is associated with improvements in the quality of sleep.Bipolar disorder is associated with elevated levels of IL-6 and in particular elevated levels of mRNA coding for IL-6 in peripheral monocytes.We propose that the changes observed in the sleep of patients with bipolar disorder are related to the elevation of IL-6 and that this correlates with an elevated expression of mRNA coding for IL-6 expression in peripheral monocytes.     

Dehydroascorbic acid for the treatment of acute ischemic stroke

In animal models of acute ischemic stroke, intravenous dehydroascorbic acid (DHAA), unlike ascorbic acid (AA), readily enters brain and is converted in both normal and ischemic brain into protective ascorbic acid. When given parenterally DHAA minimizes infarct volume and facilitates functional recovery. I hypothesize the same effect will occur in humans with acute ischemic stroke. Efficacy in reducing infarct volume is demonstrable in mice and rats even when DHAA is infused three hours after the experimental infarct. Moreover, there is fivefold mechanistic rational for DHA beside excellent pharmacokinetics and rapid penetration of brain and conversion to protective AA: (1) in ischemic brain, there is a precipitous decline in AA which can be reversed by intravenous DHAA; (2) after reduction of DHAA to AA in both normal and ischemic brain, AA can reduce oxidized vitamin E and glutathione, other protectors of brain against damaging reactive oxygen species which build up in ischemic brain; (3) AA itself can protect brain against damaging reactive oxygen species; (4) AA is an essential cofactor for several enzymes in brain including ten-eleven translocase-2 which upregulates production of protective molecules like brain-derived neurotrophic factor; and (5) DHAA after conversion to AA prevents both lipid oxidation and presumably oxidation of other labile substances (e.g., dopamine) in ischemic brain. In terms of safety, based on all available animal information, DHAA is safe in the proposed dosing regimen. For human clinical trials, the methodology for conducting the proposed animal safety, clinical pharmacology and phase II efficacy studies is straightforward. Finally, if DHAA preserved brain substance and function in humans, it could be employed in pre-hospital stroke patients.     

Impact of an autologous oxygenating matrix culture system on rat islet transplantation outcome

Disruption of the pancreatic islet environment combined with the decrease in oxygen supply that occurs during isolation leads to poor islet survival. The aim of this study was to validate the benefit of using a plasma-based scaffold supplemented with perfluorodecalin to improve islet transplantation outcome.Rat islets were cultured in three conditions: i) control group, ii) plasma based-matrix (P-matrix), and iii) P-matrix supplemented with emulsified perfluorodecalin. After 24 h culture, matrix/cell contacts (Integrinβ1, p-FAK/FAK, p-Akt/Akt), survival (caspase 3, TUNEL, FDA/PI), function, and HIF-1α translocation were assessed. Afterwards, P-matrices were dissolved and the islets were intraportally transplanted. Graft function was monitored for 31 days with glycaemia and C-peptide follow up. Inflammation was assessed by histology (macrophage and granulocyte staining) and thrombin/anti-thrombin complex measurement.Islet survival correlated with an increase in integrin, FAK, and Akt activation in P-matrices and function was maintained. Perfluorodecalin supplementation decreased translocation of HIF-1α in the nucleus and post-transplantation islet structure was better preserved in P-matrices, but a quicker activation of IBMIR resulted in early loss of graft function.“Oxygenating” P-matrices provided a real benefit to islet survival and resistance in vivo. However, intraportal transplantation is not suitable for this kind of culture due to IBMIR; thus, alternative sites must be explored.     

Expansion and differentiation of IgM+ B cells in the rainbow trout peritoneal cavity in response to different antigens

To date, intraperitoneal (i.p.) injection seems to be the most effective vaccination route in aquaculture, as many i.p. administered fish vaccines are capable of conferring strong and long-lasting immune responses. Despite this, how peritoneal leukocytes are regulated upon antigen encounter has only been scarcely studied in fish. Although, in the past, myeloid cells were thought to be the main responders to peritoneal inflammation, a recent study revealed that IgM⁺ B cells are one of the main cell types in the teleost peritoneal cavity in response to pathogenic bacteria. Thus, in the current work, we have focused on establishing how IgM⁺ B cells are recruited into the peritoneum in rainbow trout (Oncorhynchus mykiss) comparing different antigens: Escherichia coli as a bacterial model, E. coli-derived lipopolysaccharide (LPS) or viral hemorrhagic septicemia virus (VHSV). In addition to studying their capacity to dominate the peritoneal cavity, we have established how these IgM⁺ B cells are regulated in response to the different antigens, determining their levels of IgM secretion, surface MHC II expression, cell size and phagocytic abilities. Our results reveal that IgM⁺ B cells are one of the main cell types amplified in the peritoneum in response to either bacterial or viral antigens and that these immunogenic stimulations provoke a differentiation of some of these cells towards plasmablasts/plasma cells whereas others seem to be implicated in antigen presentation. These findings contribute to a better understanding of the immune processes that regulate peritoneal inflammation in teleost fish.     

Nuclear organization of cholinergic,catecholaminergic, serotonergic and orexinergic systems in the brain of the Tasmanian devil (Sarcophilus harrisii)

This study investigated the nuclear organization of four immunohistochemically identifiable neural systems (cholinergic, catecholaminergic, serotonergic and orexinergic) within the brains of three male Tasmanian devils (Sarcophilus harrisii), which had a mean brain mass of 11.6 g. We found that the nuclei generally observed for these systems in other mammalian brains were present in the brain of the Tasmanian devil. Despite this, specific differences in the nuclear organization of the cholinergic, catecholaminergic and serotonergic systems appear to carry a phylogenetic signal. In the cholinergic system, only the dorsal hypothalamic cholinergic nucleus could be observed, while an extra dorsal subdivision of the laterodorsal tegmental nucleus and cholinergic neurons within the gelatinous layer of the caudal spinal trigeminal nucleus were observed. Within the catecholaminergic system the A4 nucleus of the locus coeruleus complex was absent, as was the caudal ventrolateral serotonergic group of the serotonergic system. The organization of the orexinergic system was similar to that seen in many mammals previously studied. Overall, while showing strong similarities to the organization of these systems in other mammals, the specific differences observed in the Tasmanian devil reveal either order specific, or class specific, features of these systems. Further studies will reveal the extent of change in the nuclear organization of these systems in marsupials and how these potential changes may affect functionality.     

Dendritic cells in host response to biologic scaffolds

Tissue regeneration and repair require a highly complex and orchestrated series of events that require inflammation, but can be compromised when inflammation is excessive or becomes chronic. Macrophages are one of the first cells to contact and respond to implanted materials, and mediate the inflammatory response. The series of events following macrophage association with biomaterials has been well-studied. Dendritic cells (DCs) also directly interact with biomaterials, are critical for specific immune responses, and can be activated in response to interactions with biomaterials. Yet, much less is known about the responses by DCs. This review discusses what we know about DC response to biomaterials, the underlying mechanisms involved, and how DCs can be influenced by the macrophage response to biomaterials. Lastly, I will discuss how biomaterials can be manipulated to enhance or suppress DC function to promote a specific desirable immune response – a major goal for implantable biologically active therapeutics.     

Stress responses sculpt the insect immune system,optimizing defense in an ever-changing world

A whole organism, network approach can help explain the adaptive purpose of stress-induced changes in immune function. In insects, mediators of the stress response (e.g. stress hormones) divert molecular resources away from immune function and towards tissues necessary for fight-or-flight behaviours. For example, molecules such as lipid transport proteins are involved in both the stress and immune responses, leading to a reduction in disease resistance when these proteins are shifted towards being part of the stress response system. Stress responses also alter immune system strategies (i.e. reconfiguration) to compensate for resource losses that occur during fight-or flight events. In addition, stress responses optimize immune function for different physiological conditions. In insects, the stress response induces a pro-inflammatory state that probably enhances early immune responses.     

Bovine milk RNases modulate pro-inflammatory responses induced by nucleic acids in cultured immune and epithelial cells

Activation of innate immune receptors by exogenous substances is crucial for the detection of microbial pathogens and a subsequent inflammatory response. The inflammatory response to microbial lipopolysaccharide via Toll-like receptor 4 (TLR4) is facilitated by soluble accessory proteins, but the role of such proteins in the activation of other pathogen recognition receptors for microbial nucleic acid is not well understood. Here we demonstrate that RNase4 and RNase5 purified from bovine milk bind to Salmonella typhimurium DNA and stimulate pro-inflammatory responses induced by nucleic acid mimetics and S. typhimurium DNA in an established mouse macrophage cell culture model, RAW264.7, as well as in primary bovine mammary epithelial cells. RNase4 and 5 also modulated pro-inflammatory signalling in response to nucleic acids in bovine peripheral blood mononuclear cells, although producing a distinct response. These results support a role for RNase4 and RNase5 in mediating inflammatory signals in both immune and epithelial cells, involving mechanisms that are cell-type specific.     

Translocation of nanoparticles and Mycobacterium marinum across the intestinal epithelium in zebrafish and the role of the mucosal immune system

Nano- and microparticles are promising carrier systems for oral delivery of drugs or vaccines, particularly in fish aquaculture. However, the mechanisms of uptake, trans-epithelial transport and immune response to nano/micrometer sized particles, or microorganisms such as bacteria are poorly understood in fish. Here, adult zebrafish were used to study the uptake of different nano- and microparticles and the pathogenic bacteria Mycobacterium marinum in the intestine, and their interactions with epithelial cells and the mucosal immune system. Fluorescent particles or bacteria were delivered directly into the adult zebrafish intestine by oral intubation and their localization was imaged in intestine, liver and spleen sections. Zebrafish do not appear to have M-cells, but both nanoparticles and bacteria were rapidly taken up in the intestine and transported to the liver and spleen. In each tissue, both bacteria and particles largely localized to leukocytes, presumably macrophages.     

High levels of eukaryotic Initiation Factor 6 (eIF6) are required for immune system homeostasis and for steering the glycolytic flux of TCR-stimulated CD4+ T cells in both mice and humans

Eukaryotic Initiation Factor 6 (eIF6) is required for 60S ribosomal subunit biogenesis and efficient initiation of translation. Intriguingly, in both mice and humans, endogenous levels of eIF6 are detrimental as they act as tumor and obesity facilitators, raising the question on the evolutionary pressure that maintains high eIF6 levels. Here we show that, in mice and humans, high levels of eIF6 are required for proper immune functions. First, eIF6 heterozygous (het) mice show an increased mortality during viral infection and a reduction of peripheral blood CD4⁺ Effector Memory T cells. In human CD4⁺ T cells, eIF6 levels rapidly increase upon T-cell receptor activation and drive the glycolytic switch and the acquisition of effector functions. Importantly, in CD4⁺ T cells, eIF6 levels control interferon-γ (IFN−γ) secretion without affecting proliferation. In conclusion, the immune system has a high evolutionary pressure for the maintenance of a dynamic and powerful regulation of the translational machinery.     

Differential expression of microRNAs in shrimp Marsupenaeus japonicus in response to Vibrio alginolyticus infection

Till date numerous microRNAs (miRNAs) have been discovered from various organisms, including mammals, plants, insects, nematodes and viruses. They are known to have antiviral functions in crustaceans such as shrimp Marsupenaeus japonicas. However, little is known about the role of miRNAs against bacterial infection in this shrimp caused by Vibrio alginolyticus. We performed small RNA sequencing to characterize the differentially expressed microRNAs in V. alginolyticus challenged shrimp, in comparison to that in control uninfected shrimp, at 24 h and 48 h. In total, 55 host miRNAs were differentially expressed in response to the infection and most of these were downregulated at both the time-points. TargetScan and miRanda algorithms showed that the target genes of these down-regulated miRNAs were related to innate immune functions such as production of phenoloxidase enzyme, apoptosis and phagocytosis. Further, gene ontology analysis revealed that many immune signaling pathways were mediated by these miRNAs. This study is one of the earliest attempts at characterizing shrimp miRNAs that respond to V. alginolyticus infection, and will help unravel the miRNA pathways involved in antibacterial action in shrimp.