Bone marrow injection stimulates hepatic ductular reactions in the absence of injury via macrophage-mediated TWEAK signaling

Tissue progenitor cells are an attractive target for regenerative therapy. In various organs, bone marrow cell (BMC) therapy has shown promising preliminary results, but to date no definite mechanism has been demonstrated to account for the observed benefit in organ regeneration. Tissue injury and regeneration is invariably accompanied by macrophage infiltration, but their influence upon the progenitor cells is incompletely understood, and direct signaling pathways may be obscured by the multiple roles of macrophages during organ injury. We therefore examined a model without injury; a single i.v. injection of unfractionated BMCs in healthy mice. This induced ductular reactions (DRs) in healthy mice. We demonstrate that macrophages within the unfractionated BMCs are responsible for the production of DRs, engrafting in the recipient liver and localizing to the DRs. Engrafted macrophages produce the cytokine TWEAK (TNF-like weak inducer of apoptosis) in situ. We go on to show that recombinant TWEAK activates DRs and that BMC mediated DRs are TWEAK dependent. DRs are accompanied by liver growth, occur in the absence of liver tissue injury and hepatic progenitor cells can be isolated from the livers of mice with DRs. Overall these results reveal a hitherto undescribed mechanism linking macrophage infiltration to DRs in the liver and highlight a rationale for macrophage derived cell therapy in regenerative medicine.

Retracted manuscript

The following article from Small GTPases, “Scientific Yellow Journalism” by Anica Klockars and Michael J. Williams, published online on 20 September 2012  (doi: 10.4161/sgtp.22289; http://www.landesbioscience.com/journals/smallgtpases/article/22289/) by Landes Bioscience and subsequently published in print in Small GTPases 2012 3(4):201 has been retracted by agreement between the authors and the journal’s Editor in Chief, Michael J. Williams (also an author of the paper). 

Biogeography and body size shuffling of aquatic salamander communities on a shifting refuge

Freshwater habitats of coastal plains are refugia for many divergent vertebrate lineages, yet these environments are highly vulnerable to sea-level fluctuations, which suggest that resident communities have endured dynamic histories. Using the fossil record and a multi-locus nuclear phylogeny, we examine divergence times, biogeography, body size evolution and patterns of community assembly of aquatic salamanders from North American coastal plains since the Late Cretaceous. At least five salamander families occurred on the extensive Western Interior Coastal Plain (WICP), which existed from the Late Cretaceous through the Eocene. Four of these families subsequently colonized the emergent Southeastern Coastal Plain (SECP) by the Early Oligocene to Late Miocene. Three families ultimately survived and underwent extensive body size evolution in situ on the SECP. This included at least two major size reversals in recent taxa that are convergent with confamilial WICP ancestors. Dynamics of the coastal plain, major lineage extinctions and frequent extreme changes in body size have resulted in significant shuffling of the size structure of aquatic salamander communities on this shifting refuge since the Cretaceous.

What model organisms and interactomics can reveal about the genetics of human obesity

Genome-wide association studies have identified a number of genes associated with human body weight. While some of these genes are large fields within obesity research, such as MC4R, POMC, FTO and BDNF, the majority do not have a clearly defined functional role explaining why they may affect body weight. Here, we searched biological databases and discovered 33 additional genes associated with human obesity (CADM2, GIPR, GPCR5B, LRP1B, NEGR1, NRXN3, SH2B1, FANCL, GNPDA2, HMGCR, MAP2K5, NUDT3, PRKD1, QPCTL, TNNI3K, MTCH2, DNAJC27, SLC39A8, MTIF3, RPL27A, SEC16B, ETV5, HMGA1, TFAP2B, TUB, ZNF608, FAIM2, KCTD15, LINGO2, POC5, PTBP2, TMEM18, TMEM160). We find that the majority have orthologues in distant species, such as D. melanogaster and C. elegans, suggesting that they are important for the biology of most bilateral species. Intriguingly, signalling cascade genes and transcription factors are enriched among these obesity genes, and several of the genes show properties that could be useful for potential drug discovery. In this review, we demonstrate how information from several distant model species, interactomics and signalling pathway analysis represents an important way to better understand the functional diversity of the surprisingly high number of molecules that seem to be important for human obesity.

The RhoGEF Zizimin-related acts in the Drosophila cellular immune response via the Rho GTPases Rac2 and Cdc42

Zizimin-related (Zir), a Rho guanine nucleotide exchange factor (RhoGEF) homologous to the mammalian Dock-C/Zizimin-related family, was identified in a screen to find new genes involved in the Drosophila melanogaster cellular immune response against eggs from the parasitoid wasp Leptopilina boulardi. RhoGEFs activate Rho-family GTPases, which are known to be central regulators of cell migration, spreading and polarity. When a parasitoid wasp is recognized as foreign, multiple layers of circulating immunosurveillance cells (haemocytes) should attach to the egg. In Zir mutants this process is disrupted and lamellocytes, a haemocyte subtype, fail to properly encapsulate the wasp egg. Furthermore, macrophage-like plasmatocytes exhibit a strong reduction in their ability to phagocytise Escherichia coli and Staphylococcus aureus bacteria. During encapsulation and phagocytosis Zir genetically interacts with two Rho-family GTPases, Rac2 and Cdc42. Finally, Zir is dispensable for the humoral immune response against bacteria. We propose that Zir is necessary to activate the Rho-family GTPases Rac2 and Cdc42 during the Drosophila cellular immune response.

Real-time analysis of Drosophila post-embryonic haemocyte behaviour

BACKGROUND

The larval stage of the model organism Drosophila is frequently used to study host-pathogen interactions. During embryogenesis the cellular arm of the immune response, consisting of macrophage-like cells known as plasmatocytes, is extremely motile and functions to phagocytise pathogens and apoptotic bodies, as well as produce extracellular matrix. The cellular branch of the larval (post-embryonic) innate immune system consists of three cell types--plasmatocytes, crystal cells and lamellocytes--which are involved in the phagocytosis, encapsulation and melanisation of invading pathogens. Post-embryonic haemocyte motility is poorly understood thus further characterisation is required, for the purpose of standardisation.

METHODOLOGY

In order to examine post-embryonic haemocyte cytoskeletal dynamics or migration, the most commonly used system is in vitro cell lines. The current study employs an ex vivo system (an adaptation of in vitro cell incubation using primary cells), in which primary larval or pre-pupal haemocytes are isolated for short term analysis, in order to discover various aspects of their behaviour during events requiring cytoskeleton dynamics.

SIGNIFICANCE

The ex vivo method allows for real-time analysis and manipulation of primary post-embryonic haemocytes. This technique was used to characterise, and potentially standardised, larval and pre-pupal haemocyte cytoskeleton dynamics, assayed on different extracellular matrices. Using this method it was determined that, while larval haemocytes are unable to migrate, haemocytes recovered from pre-pupae are capable of migration.

Drosophila cellular immunity: a story of migration and adhesion

Research during the past 15 years has led to significant breakthroughs, providing evidence of a high degree of similarity between insect and mammalian innate immune responses, both humoural and cellular, and highlighting Drosophila melanogaster as a model system for studying the evolution of innate immunity. In a manner similar to cells of the mammalian monocyte and macrophage lineage, Drosophila immunosurveillance cells (haemocytes) have a number of roles. For example, they respond to wound signals, are involved in wound healing and contribute to the coagulation response. Moreover, they participate in the phagocytosis and encapsulation of invading pathogens, are involved in the removal of apoptotic bodies and produce components of the extracellular matrix. There are several reasons for using the Drosophila cellular immune response as a model to understand cell signalling during adhesion and migration in vivo: many genes involved in the regulation of Drosophila haematopoiesis and cellular immunity have been maintained across taxonomic groups ranging from flies to humans, many aspects of Drosophila and mammalian innate immunity seem to be conserved, and Drosophila is a simplified and well-studied genetic model system. In the present Commentary, we will discuss what is known about cellular adhesion and migration in the Drosophila cellular immune response, during both embryonic and larval development, and where possible compare it with related mechanisms in vertebrates.

The Rho-family GTPase Rac1 regulates integrin localization in Drosophila immunosurveillance cells

Background

When the parasitoid wasp Leptopilina boulardi lays an egg in a Drosophila larva, phagocytic cells called plasmatocytes and specialized cells known as lamellocytes encapsulate the egg. The Drosophila β-integrin Myospheroid (Mys) is necessary for lamellocytes to adhere to the cellular capsule surrounding L. boulardi eggs. Integrins are heterodimeric adhesion receptors consisting of α and β subunits, and similar to other plasma membrane receptors undergo ligand-dependent endocytosis. In mammalian cells it is known that integrin binding to the extracellular matrix induces the activation of Rac GTPases, and we have previously shown that Rac1 and Rac2 are necessary for a proper encapsulation response in Drosophila larvae. We wanted to test the possibility that Myospheroid and Rac GTPases interact during the Drosophila anti-parasitoid immune response.

Results

In the current study we demonstrate that Rac1 is required for the proper localization of Myospheroid to the cell periphery of haemocytes after parasitization. Interestingly, the mislocalization of Myospheroid in Rac1 mutants is rescued by hyperthermia, involving the heat shock protein Hsp83. From these results we conclude that Rac1 and Hsp83 are required for the proper localization of Mys after parasitization.

Significance

We show for the first time that the small GTPase Rac1 is required for Mysopheroid localization. Interestingly, the necessity of Rac1 in Mys localization was negated by hyperthermia. This presents a problem, in Drosophila we quite often raise larvae at 29°C when using the GAL4/UAS misexpression system. If hyperthermia rescues receptor endosomal recycling defects, raising larvae in hyperthermic conditions may mask potentially interesting phenotypes.

Progression of initially mild hepatic fibrosis in patients with chronic hepatitis C infection

A significant number of patients with chronic hepatitis C infection have minimal fibrosis at presentation. Although the short-term outlook for such patients is good, there are limited data available on long-term progression. We assessed the risk of fibrosis progression in 282 patients with chronic hepatitis C with Ishak stage 0 or 1 fibrosis on initial liver biopsy. Progression of fibrosis stage occurred in 118 patients (42%) over a median interval of 52.5 months. Thirteen (5%) progressed to severe (Ishak stage 4 or more) fibrosis. Progression was significantly associated with both age at initial biopsy [odds ratio (OR) for progression of 1.31 per 10 year increase in age] and median alanine transaminase (ALT) levels during follow-up (OR of 1.06 per 10 IU/L increase). There was no significant association with gender, histological inflammatory grade, hepatic steatosis or body mass index. We conclude that hepatitis C with initially mild fibrosis does progress in a substantial proportion of patients and should not be viewed as a benign disease. Early antiviral therapy should be considered in older patients and those with high ALT levels.

Taxing junk food: applying the logic of the Henry tax review to food

The recent review of taxation in Australia - the Henry tax review - has recommended that the federal government increase the taxes already levied on tobacco and alcohol. Tobacco and alcohol taxes are put forward as the best way of reducing the social harms caused by the use and misuse of these substances. Junk foods have the same pattern of misuse and the same social costs as tobacco and alcohol. The Henry tax review rejects the idea of taxing fatty foods, and to date the government has not implemented a tax on junk food. We propose that a tax on junk food be implemented as a tool to reduce consumption and address the obesity epidemic.

Resource expenditure not resource allocation: response to McDougall on cloning and dignity

This paper offers some comments on bioethical debates about resource allocation in healthcare. It is stimulated by Rosalind McDougall's argument that it is an affront to the human dignity of people with below "liberties-level" health to fund human reproductive cloning. McDougall is right to underline the relevance of resource prioritisation to the ethics of research and provision of new biomedical technologies. This paper argues that bioethicists should be careful when offering comments about such issues. In particular, it emphasises the need to represent accurately the reality of the situation-especially when we are passing judgement on technologies that are in their infancy and whose practical application is yet to be confirmed. The paper also emphasises the importance of the actual context to bioethical debate, and note that it would be better to talk about resource expenditure rather than resource allocation when it comes to discussing the rights and wrongs of how money is spent. It also reiterates the claims made by other writers that social and political philosophy need to have a transparent and considered role in debates about resources.

Autoantibodies in chronic hepatitis C virus infection and their association with disease profile

Autoantibodies are commonly detected in chronic hepatitis C (HCV) but their significance remains uncertain. We assessed the prevalence of anti-nuclear (ANA) and anti-smooth muscle (ASM) antibodies within a cohort of 963 treatment-naïve HCV patients. We also assessed for differences between autoantibody-positive and autoantibody-negative patients in demographics, markers of disease activity and response to anti-viral treatment. One hundred and seventy-two patients (17.9%) had at least one autoantibody, of which were 104 (10.8%) ASM, 54 (5.6%) ANA and 14 (1.5%) positive for both. Autoantibody-positive patients were older (43 vs 39 years, P = 0.001) caused by an age-related increase in ANA (but not ASM). There were no differences in gender, alcohol intake, ethnicity or viral genotype. The presence of autoantibodies, and specifically ASM, was associated with an increase in interface hepatitis score amongst men (1.1 vs 0.8, P = 0.005) but no difference in other necroinflammatory measures, liver function tests or immunoglobulins (Ig). There was no difference in initial fibrosis stage or rate of fibrosis progression. Autoantibodies did not affect response to anti-viral treatment. We conclude that autoantibodies are frequent in HCV infection. Anti-nuclear antibodies increase with age, whereas ASM antibodies are associated with interface hepatitis in men. Neither autoantibody carries increased risk of fibrosis progression or failure of therapy.

Expansion of the D system of horse red cell alloantigens

Two additional specificities (Dq and Dr) were assigned to the D system of horse red cell alloantigens following discussion of the 1989 ISAG Horse Comparison Test (HCT) results. Family and population data support 25 phenogroups defined by the enhanced battery of 17 D system factors.

The Drosophila cell adhesion molecule Neuroglian regulates Lissencephaly-1 localisation in circulating immunosurveillance cells

Background

When the parasitoid wasp Leptopilina boulardi lays its eggs in Drosophila larvae phagocytic cells called plasmatocytes and specialized cells known as lamellocytes encapsulate the egg. This requires these circulating immunosurveillance cells (haemocytes) to change from a non-adhesive to an adhesive state enabling them to bind to the invader. Interestingly, attachment of leukocytes, platelets, and insect haemocytes requires the same adhesion complexes as epithelial and neuronal cells.

Results

Here evidence is presented showing that the Drosophila L1-type cell adhesion molecule Neuroglian (Nrg) is required for haemocytes to encapsulate L. boulardi wasp eggs. The amino acid sequence FIGQY containing a conserved phosphorylated tyrosine is found in the intracellular domain of all L1-type cell adhesion molecules. This conserved tyrosine is phosphorylated at the cell periphery of plasmatocytes and lamellocytes prior to parasitisation, but dephosphorylated after immune activation. Intriguingly, another pool of Nrg located near the nucleus of plasmatocytes remains phosphorylated after parasitisation. In mammalian neuronal cells phosphorylated neurofascin, another L1-type cell adhesion molecule interacts with a nucleokinesis complex containing the microtubule binding protein lissencephaly-1 (Lis1) [1]. Interestingly in plasmatocytes from Nrg mutants the nucleokinesis regulating protein Lissencephaly-1 (Lis1) fails to localise properly around the nucleus and is instead found diffuse throughout the cytoplasm and at unidentified perinuclear structures. After attaching to the wasp egg control plasmatocytes extend filopodia laterally from their cell periphery; as well as extending lateral filopodia plasmatocytes from Nrg mutants also extend many filopodia from their apical surface.

Conclusion

The Drosophila cellular adhesion molecule Neuroglian is expressed in haemocytes and its activity is required for the encapsulation of L. boularli eggs. At the cell periphery of haemocytes Neuroglian may be involved in cell-cell interactions, while at the cell centre Neuroglian regulates the localisation of the nucleokinesis complex protein lissencephaly-1.

Services for liver disease in district general hospitals in the UK: a national questionnaire-based survey

The burden of liver disease in the UK is increasing and much of this is managed in district general hospitals (DGHs). Previous studies of liver services have focused on specialist units. This study assessed the provision of liver services in non-specialist units. A questionnaire-based survey was conducted to assess resources, staffing and clinical management of liver disease. Replies were received from 61 consultant gastroenterologists working in DGHs across the UK. The data show inadequate consultant numbers and limited availability of nurse specialists, hepatobiliary pathologists and radiologists. There is marked variability in the management of hepatitis C, variceal bleeding and hepatorenal syndrome. Liver databases and outcomes are rarely kept. There are significant shortfalls in the provision of liver services across DGHs. This supports the need for managed clinical networks and data collection as proposed in the National Plan for Liver Services.