Presence of Anti-Microbial Antibodies in Liver Cirrhosis – A Tell-Tale Sign of Compromised Immunity?

Background

Bacterial translocation plays important role in the complications of liver cirrhosis. Antibody formation against various microbial antigens is common in Crohn''s disease and considered to be caused by sustained exposure to gut microflora constituents. We hypothesized that anti-microbial antibodies are present in patients with liver cirrhosis and may be associated with the development of bacterial infections.

Methodology/Principal Findings

Sera of 676 patients with various chronic liver diseases (autoimmune diseases:266, viral hepatitis C:124, and liver cirrhosis of different etiology:286) and 100 controls were assayed for antibodies to Saccharomyces cerevisiae(ASCA) and to antigens derived from two intestinal bacterial isolates (one gram positive, one gram negative, neither is Escherichia coli). In patients with liver cirrhosis, we also prospectively recorded the development of severe episodes of bacterial infection. ASCA and anti-OMP Plus™ antibodies were present in 38.5% and 62.6% of patients with cirrhosis and in 16% and 20% of controls, respectively (p<0.001). Occurrence of these antibodies was more frequent in cases of advanced cirrhosis (according to Child-Pugh and MELD score; p<0.001) or in the presence of ascites (p<0.001). During the median follow-up of 425 days, 81 patients (28.3%) presented with severe bacterial infections. Anti-microbial antibody titers (p = 0.003), as well as multiple seroreactivity (p = 0.036), was associated with infectious events. In logistic regression analysis, the presence of ascites (OR:1.62, 95%CI:1.16–2.25), co-morbidities (OR:2.22, 95%CI:1.27–3.86), and ASCA positivity (OR:1.59, 95%CI:1.07–2.36) were independent risk factors for severe infections. A shorter time period until the first infection was associated with the presence of ASCA (p = 0.03) and multiple seropositivity (p = 0.037) by Kaplan-Meier analysis, and with Child-Pugh stage (p = 0.018, OR:1.85) and co-morbidities (p<0.001, OR:2.02) by Cox-regression analysis.

Conclusions/Significance

The present study suggests that systemic reactivity to microbial components reflects compromised mucosal immunity in patients with liver cirrhosis, further supporting the possible role of bacterial translocation in the formation of anti-microbial antibodies.     

Characterization of velogenic Newcastle disease viruses isolated from dead wild birds in Serbia during 2007

Avian paramyxoviruses type 1 or Newcastle disease viruses (NDV) are frequently recovered from wild birds and such isolates are most frequently of low virulence. Velogenic NDV are usually recovered from poultry and only occasionally from wild birds. Five NDV isolates were obtained from carcasses of four wild bird species during 2007 in Serbia: Mallard (Anas platyrhynchos), Eurasian Sparrowhawk (Accipiter nisus), feral Rock Pigeon (Columba livia), and Eurasian Collared Dove (Streptopelia decaocto). All the isolates have a typical fusion protein cleavage site motif of velogenic viruses ((112)R-R-Q-K-R-F(117)). The highest homology (99%) for the nucleotide sequences spanning the M and F gene of the studied isolates was with the genotype VII NDV isolate Muscovy duck/China(Fujian)/FP1/02. Phylogenetic analysis based on a partial F gene sequence showed that the isolates from wild birds cluster together with concurrent isolates from poultry in Serbia within the subgenotype VIId, which is the predominant pathogen involved currently in Newcastle disease outbreaks in poultry worldwide. It is unlikely that the wild birds played an important role in primary introduction or consequent spread of the velogenic NDV to domestic poultry in Serbia, and they probably contracted the virus from locally infected poultry.     

Verification of alternative splicing variants based on domain integrity, truncation length and intrinsic protein disorder

According to current estimations ～95% of multi-exonic human protein-coding genes undergo alternative splicing (AS). However, for 4000 human proteins in PDB, only 14 human proteins have structures of at least two alternative isoforms. Surveying these structural isoforms revealed that the maximum insertion accommodated by an isoform of a fully ordered protein domain was 5 amino acids, other instances of domain changes involved intrinsic structural disorder. After collecting 505 minor isoforms of human proteins with evidence for their existence we analyzed their length, protein disorder and exposed hydrophobic surface. We found that strict rules govern the selection of alternative splice variants aimed to preserve the integrity of globular domains: alternative splice sites (i) tend to avoid globular domains or (ii) affect them only marginally or (iii) tend to coincide with a location where the exposed hydrophobic surface is minimal or (iv) the protein is disordered. We also observed an inverse correlation between the domain fraction lost and the full length of the minor isoform containing the domain, possibly indicating a buffering effect for the isoform protein counteracting the domain truncation effect. These observations provide the basis for a prediction method (currently under development) to predict the viability of splice variants.     

Paracrine effects of mesenchymal stem cells in cisplatin-induced renal injury require heme oxygenase-1

Multipotent mesenchymal stem cells (MSC) have become a popular and promising therapeutic approach in many clinical conditions. MSC are beneficial in animal models of acute kidney injury (AKI), by mediating differentiation-independent paracrine properties, and have prompted ongoing clinical trials to evaluate the safety and efficacy of MSC. Heme oxygenase-1 (HO-1) is induced in response to stress including AKI and has important anti-apoptotic, anti-inflammatory, and proangiogenic properties in these settings. We therefore examined whether HO-1 plays a role in the beneficial effects of MSC in AKI. We isolated MSC from bone marrow of age-matched HO-1+/+ and HO-1-/- mice. Our studies indicate that while differentiation of MSC into osteo- and adipocytic lineages did not differ between cells isolated from HO-1+/+ and HO-1-/- mice, MSC from HO-1-/- mice had significantly lower angiogenic potential. Moreover, HO-1-/- MSC demonstrated reduced expression and secretion of several important growth and proangiogenic factors (stromal cell-derived factor-1, vascular endothelial growth factor-A, and hepatocyte growth factor) compared with MSC derived from HO-1+/+ mice. In addition, conditioned medium of HO-1+/+ MSC rescued functional and morphological changes associated with cisplatin-induced AKI, while the HO-1-/--conditioned medium was ineffectual. Our studies indicate that HO-1 plays an important role in MSC-mediated protection. The results expand understanding of the renoprotective effects of MSC and may provide novel strategies to better utilize MSC in various disease models.     

Ano1 as a regulator of proliferation

Ano1 is a recently discovered Ca(2+)-activated Cl(-) channel expressed on interstitial cells of Cajal (ICC) that has been implicated in slow-wave activity in the gut. However, Ano1 is expressed on all classes of ICC, even those that do not contribute to generation of the slow wave, suggesting that Ano1 may have an alternate function in these cells. Ano1 is also highly expressed in gastrointestinal stromal tumors. Mice lacking Ano1 had fewer proliferating ICC in whole mount preparations and in culture, raising the possibility that Ano1 is involved in proliferation. Cl(-) channel blockers decreased proliferation in cells expressing Ano1, including primary cultures of ICC and in the pancreatic cancer-derived cell line, CFPAC-1. Cl(-) channel blockers had a reduced effect on Ano1(-/-) cultures, confirming that the blockers are acting on Ano1. Ki67 immunoreactivity, 5-ethynyl-2'-deoxyuridine incorporation, and cell-cycle analysis of cells grown in low-Cl(-) media showed fewer proliferating cells than in cultures grown in regular medium. We confirmed that mice lacking Ano1 had less phosphorylated retinoblastoma protein compared with controls. These data led us to conclude that Ano1 regulates proliferation at the G(1)/S transition of the cell cycle and may play a role in tumorigenesis.     

Influence of +1245 A/G MT1A polymorphism on advanced glycation end-products (AGEs) in elderly: effect of zinc supplementation

Advanced glycation end-products (AGEs) stimulate reactive oxygen species (ROS) generation and represent a risk factor for atherosclerosis, while their formation seems to be prevented by zinc. Metallothioneins (MT), zinc-binding proteins exert an antioxidant function by regulating intracellular zinc availability and protecting cells from ROS damages. +1245 A/G MT1A polymorphism was implicated in type 2 diabetes and in cardiovascular disease development as well as in the modulation of antioxidant response. The purpose of this study was to investigate the influence of +1245 A/G MT1A polymorphism on AGEs and ROS production and to verify the effect of zinc supplementation on plasma AGEs, zinc status parameters and antioxidant enzyme activity in relation to this SNP. One hundred and ten healthy subjects (72 ± 6 years) from the ZincAge study were supplied with zinc aspartate (10 mg/day for 7 weeks) and screened for +1245 MT1A polymorphism. +1245 MT1A G+ (Arginine) genotype showed higher plasma AGEs and ROS production in peripheral blood mononuclear cells (PBMCs) than G− (Lysine) one at the baseline. No significant changes after zinc supplementation were observed for AGEs, ROS and MT levels as well as for enzyme antioxidant activity in relation to the genotype. Among zinc status parameters, major increases were observed for the intracellular labile zinc (iZnL) and the NO-induced release of zinc in PBMCs, in G+ genotype as compared to G− one. In summary, +1245 G+ carriers showed increased plasma AGEs and ROS production in PBMCs at baseline and a higher improvement in iZnL after zinc intervention with respect to G− individuals.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-014-0426-2) contains supplementary material, which is available to authorized users.     

Bioactive compounds in sweet rowanberry fruits of interspecific Rowan crosses

Sweet rowanberries originated by the crossbreeding of wild rowanberries with other fruit species such as apples, medlars or black chokeberries. They are highly resistant to cold climate. In contrast with wild rowanberries, they have sweet mild taste and show less parasorbic acid toxicity, which can be eliminated, when the consumption is excessive, by heating. The objective of the work was to determine selected antioxidant properties in 6 cultivars. The analyses showed that the contents of total phenolics, total flavonoids and ascorbic acid were high. Similarly, antioxidant capacity (6.58–9.62 g of ascorbic acid equivalents kg^?1) was also high. The work brings novel data, in particular, when comparing the cultivars; moreover, results regarding reactive oxygen and nitrogen species scavenging activity in sweet rowanberries are being published for the first time. The sweet rowanberry extracts (10%) showed inhibitory ability on hydroxyl radical (16.12–24.73%), superoxide anion (26.74–34.02%), nitric oxide (24.75–31.39%), and lipid peroxidation (7.93–13.12%). The values obtained are even many times higher than those found in common commercial fruit species like apples. Therefore, sweet rowanberries appear to be a promising fruit species for human nutrition, especially due to their high content of bioactive substances and ease of cultivation in worse climatic and soil conditions.     

Genetic Deletion of Mst1 Alters T Cell Function and Protects against Autoimmunity

Mammalian sterile 20-like kinase 1 (Mst1) is a MAPK kinase kinase kinase which is involved in a wide range of cellular responses, including apoptosis, lymphocyte adhesion and trafficking. The contribution of Mst1 to Ag-specific immune responses and autoimmunity has not been well defined. In this study, we provide evidence for the essential role of Mst1 in T cell differentiation and autoimmunity, using both genetic and pharmacologic approaches. Absence of Mst1 in mice reduced T cell proliferation and IL-2 production in vitro, blocked cell cycle progression, and elevated activation-induced cell death in Th1 cells. Mst1 deficiency led to a CD4⁺ T cell development path that was biased toward Th2 and immunoregulatory cytokine production with suppressed Th1 responses. In addition, Mst1^−/− B cells showed decreased stimulation to B cell mitogens in vitro and deficient Ag-specific Ig production in vivo. Consistent with altered lymphocyte function, deletion of Mst1 reduced the severity of experimental autoimmune encephalomyelitis (EAE) and protected against collagen-induced arthritis development. Mst1^−/− CD4⁺ T cells displayed an intrinsic defect in their ability to respond to encephalitogenic antigens and deletion of Mst1 in the CD4⁺ T cell compartment was sufficient to alleviate CNS inflammation during EAE. These findings have prompted the discovery of novel compounds that are potent inhibitors of Mst1 and exhibit desirable pharmacokinetic properties. In conclusion, this report implicates Mst1 as a critical regulator of adaptive immune responses, Th1/Th2-dependent cytokine production, and as a potential therapeutic target for immune disorders.