Loss of ability to self-heal malaria upon taurine transporter deletion

Malaria-derived exosomes exacerbate liver injury during blood stage of Plasmodium berghei infection

Liver injury is a common clinical feature of Plasmodium spp. infection and contributes to multi-organ failure of severe malaria. Malaria-derived exosomes (MD-Exos) have recently engaged as key mediators in parasite-host interactions, modulating the subsequent pathogenic process. However, the role of MD-Exos in malaria-related liver injury and the underlying mechanisms remain unclear. Herein, exosomes from C57BL/6 mice infected with or without P. berghei ANKA serum (namely inf-Exos or un-Exos) were isolated and characterized by transmission electron microscopy, western blotting, and nanoparticle tracking analysis. The miRNAs profiling between inf-Exos and un-Exos were generated using RNA-seq and qPCR. The functions of inf-Exos on liver injury were investigated after two types of exosomes injected into mice intravenously (i.v.), by examining histopathological and apoptotic changes, macrophage polarization, and pro-inflammatory response. The infected red blood cells-stimulated mouse Raw264.7 macrophage cells targeted by inf-Exos or un-Exos were cultured for further study and verification the potential mechanisms. We found that both inf-Exos and un-Exos displayed a typical cup-shaped structure with a diameter of 60-200 nm, and had a positive expression of exosomal markers (e.g., CD9, CD63, and CD81). Compared with infected control mice, the treatment of inf-Exos but not un-Exos dramatically enhanced peripheral blood parasitemia and ECM incidence, exacerbated liver histopathological damage, elevated numbers of liver apoptotic cells, CD68⁺and CD86⁺ macrophages. The CD68⁺-TREM-1⁺ macrophages in liver tissues and the mRNA levels of pro-inflammatory cytokines (e.g., iNOS, TNF-α, IL-1β, and IL-6) were increased by inf-Exos treatment in vivo. Meanwhile, the treatment of inf-Exos resulted in a substantial increase of the mRNA levels of CD86, iNOS, TNF-α, IL-1β, and IL-6, but led to a remarkable decrease of Bcl-6 and SOCS-1 in Raw264.7 cells stimulated with iRBC in vitro. Notably, compared to un-Exos, five types of miRNAs (including miR-10a-5p, miR-10b-5p, miR-155-5p, miR-205-5p, and miR-21a-5p), that were previously reported to target Bcl-6 or SOCS-1, present higher abundance on inf-Exos, as demonstrated by RNA-seq and qPCR. Collectively, our data suggest that inf-Exos exacerbate malaria-induced liver pathology via triggering excessive pro-inflammatory response and promoting macrophage M1 polarization. Our findings will provide new insights into the roles of inf-Exos in malaria parasite-host interaction and pathogenesis of liver injury.

Characterization of the Gene Expression Patterns in the Murine Liver Following Intramuscular Administration of Baculovirus

Intramuscular administration of wild-type baculovirus is able to both protect against Plasmodium sporozoite challenge and eliminate liver-stage parasites via a Toll-like receptor 9-independent pathway. To investigate its effector mechanism(s), the gene expression profile in the liver of baculovirus-administered mice was characterized by cDNA microarray analysis. The ingenuity pathway analysis gene ontology module revealed that the major gene subsets induced by baculovirus were immune-related signaling, such as interferon signaling. A total of 40 genes commonly upregulated in a Toll-like receptor 9-independent manner were included as possible candidates for parasite elimination. This gene subset consisted of NT5C3, LOC105246895, BTC, APOL9a/b, G3BP3, SLC6A6, USP25, TRIM14, and PSMB8 as the top 10 candidates according to the special unit. These findings provide new insight into effector molecules responsible for liver-stage parasite killing and, possibly, the development of a new baculovirus-mediated prophylactic and therapeutic biopharmaceutical for malaria.

Protective Vaccination Reshapes Hepatic Response to Blood-Stage Malaria of Genes Preferentially Expressed by NK Cells

The role of natural killer (NK) cells in the liver as first-line post infectionem (p.i.) effectors against blood-stage malaria and their responsiveness to protective vaccination is poorly understood. Here, we investigate the effect of vaccination on NK cell-associated genes induced in the liver by blood-stage malaria of Plasmodium chabaudi. Female Balb/c mice were vaccinated at weeks 3 and 1 before being infected with 10⁶P. chabaudi-parasitized erythrocytes. Genes preferentially expressed by NK cells were investigated in livers of vaccination-protected and non-protected mice on days 0, 1, 4, 8, and 11 p.i. using microarrays, qRT-PCR, and chromosome landscape analysis. Blood-stage malaria induces expression of specific genes in the liver at different phases of infection, i.e., Itga1 in expanding liver-resident NK (lrNK) cells, Itga2 in immigrating conventional NK (cNK) cells; Eomes and Tbx21 encoding transcription factors; Ncr1, Tnfsf10, Prf1, Gzma, Gzmb, Gzmc, Gzmm, and Gzmk encoding cytolytic effectors; natural killer gene complex (NKC)-localized genes encoding the NK cell receptors KLRG1, KLRK1, KLRAs1, 2, 5, 7, KLRD1, KLRC1, KLRC3, as well as the three receptors KLRB1A, KLRB1C, KLRB1F and their potential ligands CLEC2D and CLEC2I. Vaccination enhances this malaria-induced expression of genes, but impairs Gzmm expression, accelerates decline of Tnfsf10 and Clec2d expression, whereas it accelerates increased expression of Clec2i, taking a very similar time course as that of genes encoding plasma membrane proteins of erythroblasts, whose malaria-induced extramedullary generation in the liver is known to be accelerated by vaccination. Collectively, vaccination reshapes the response of the liver NK cell compartment to blood-stage malaria. Particularly, the malaria-induced expansion of lrNK cells peaking on day 4 p.i. is highly significantly (p < 0.0001) reduced by enhanced immigration of peripheral cNK cells, and KLRB1F:CLEC2I interactions between NK cells and erythroid cells facilitate extramedullary erythroblastosis in the liver, thus critically contributing to vaccination-induced survival of otherwise lethal blood-stage malaria of P. chabaudi.

An NF-κB-driven lncRNA orchestrates colitis and circadian clock

We uncover a cycling and NF-κB-driven lncRNA (named Lnc-UC) that epigenetically modifies transcription of circadian clock gene Rev-erbα, thereby linking circadian clock to colitis. Cycling expression of Lnc-UC is generated by the central clock protein Bmal1 via an E-box element. NF-κB activation in experimental colitis transcriptionally drives Lnc-UC through direct binding to two κB sites. Lnc-UC ablation disrupts colonic expressions of clock genes in mice; particularly, Rev-erbα is down-regulated and its diurnal rhythm is blunted. Consistently, Lnc-UC promotes expression of Rev-erbα (a known dual NF-κB/Nlrp3 repressor) to inactivate NF-κB signaling and Nlrp3 inflammasome in macrophages. Furthermore, Lnc-UC ablation sensitizes mice to experimental colitis and abolishes the diurnal rhythmicity in disease severity. Mechanistically, Lnc-UC physically interacts with Cbx1 protein to reduce its gene silencing activity via H3K9me3, thereby enhancing Rev-erbα transcription and expression. In addition, we identify a human Lnc-UC that has potential to promote Rev-erbα expression and restrain inflammations.

The Anti-Inflammatory Effect of Taurine on Cardiovascular Disease

Taurine is a non-protein amino acid that is expressed in the majority of animal tissues. With its unique sulfonic acid makeup, taurine influences cellular functions, including osmoregulation, antioxidation, ion movement modulation, and conjugation of bile acids. Taurine exerts anti-inflammatory effects that improve diabetes and has shown benefits to the cardiovascular system, possibly by inhibition of the renin angiotensin system. The beneficial effects of taurine are reviewed.

Vaccination accelerates hepatic erythroblastosis induced by blood-stage malaria

Background

Vaccination induces survival of otherwise lethal blood-stage infections of the experimental malaria Plasmodium chabaudi. Blood-stage malaria induces extramedullary erythropoiesis in the liver. This study investigates how vaccination affects the course of malaria-induced expression of erythrocytic genes in the liver.

Methods

Female Balb/c mice were vaccinated at week 3 and week 1 before challenging with 10⁶P. chabaudi-parasitized erythrocytes. The non-infectious vaccine consisted of erythrocyte ghosts isolated from P. chabaudi-infected erythrocytes. Gene expression microarrays and quantitative real-time PCR were used to compare mRNA expression of different erythrocytic genes in the liver of vaccination-protected and non-protected mice during infections on days 0, 1, 4, 8, and 11 p.i.

Results

Global transcriptomics analyses reveal vaccination-induced modifications of malaria-induced increases in hepatic gene expression on days 4 and 11 p.i. On these days, vaccination also alters hepatic expression of the erythropoiesis-involved genes Ermap, Kel, Rhd, Rhag, Slc4a1, Gypa, Add2, Ank1, Epb4.1, Epb4.2, Epb4.9, Spta1, Sptb, Tmod1, Ahsp, Acyp1, Gata1, Gfi1b, Tal1, Klf1, Epor, and Cldn13. In vaccination-protected mice, expression of these genes, except Epb4.1, is significantly higher on day 4 p.i. than in un-protected non-vaccinated mice, reaches maximal expression at peak parasitaemia on day 8 p.i., and is slowed down or even decreased towards the end of crisis phase on day 11 p.i.. After day 1 p.i., Epor expression takes about the same course as that of the other erythroid genes. Hepatic expression of Epo, however, is delayed in both vaccinated and non-vaccinated mice for the first 4 days p.i. and is maximal at significantly higher levels in vaccinated mice on day 8 p.i., before declining towards the end of crisis phase on day 11 p.i.

Conclusion

The present data indicate that vaccination accelerates malaria-induced erythroblastosis in the liver for 1–2 days. This may contribute to earlier replenishment of peripheral red blood cells by liver-derived reticulocytes, which may favour final survival of otherwise lethal blood-stage malaria, since reticulocytes are not preferred as host cells by P. chabaudi.

Disordered Metabolic Profiling in Plasma and Tissues of Mice Infected with Artemisinin-Sensitive and -Resistant Plasmodium berghei K173 Determined by 1H NMR Spectroscopy

Artemisinin resistance has inevitably emerged in several malaria-endemic areas and led to an incremental clinical failure rate for artemisinin-based combination therapy (ACT), which is strongly recommended by the World Health Organization (WHO). Genetically resilient malaria parasites have evolved antimalarial drug-evasion mechanisms; meanwhile, the metabolic cross-talk between the malaria parasites and the host is of significance during the invasion. The intention of this work, therefore, is to propose a feasible method to discover the systematic metabolic phenotypes of mice invaded with artemisinin-sensitive or -resistant Plasmodium berghei K173 when compared with healthy mice. Biological samples, including plasma, liver, spleen, and kidney, of mice collected after euthanasia at day 7 were subjected to ¹H nuclear magnetic resonance spectroscopy. Multivariable data analysis was utilized to estimate the metabolic characteristics of these samples from uninfected and infected mice. In contrast with healthy mice, both sensitive and resistant malaria-parasite-infected models displayed distinct metabolic profiles. Parasite invasion significantly changed the glycolysis, Kreb's cycle, and amino acid metabolism in plasma and tissues. Decreased N, N-dimethylglycine and glycine levels in plasma from the artemisinin-sensitive P. berghei-infected group and increased lactate, lipid, and aspartate in the artemisinin-resistant P. berghei-infected group were observed, respectively. In the liver, the artemisinin-sensitive group up-regulated the glutamate level and down-regulated glutamine. Artemisinin-resistant parasite exposure decreased ethanol and allantoin levels. The levels of myo-inositol and valine in the spleen were increased due to artemisinin-sensitive P. berghei infection, together with decreased trimethylamine N-oxide, phosphocholine, β-glucose, and acetoacetic acid. In the artemisinin-resistant group, the spleen showed a remarkably increased phosphocholine content along with decreased dimethylglycine and arginine levels. In the kidney, artemisinin-sensitive P. berghei K173 caused increased lysine, glutamate, creatine, and 2-hydroxybutyrate as well as decreased ethanol. Artemisinin-resistant P. berghei led to low glycerophosphorylcholine and high acetate, betaine, and hypoxanthine. Mutual and specific altered metabolites and, accordingly, metabolic pathways induced by the infection of artemisinin-sensitive or -resistant P. berghei were therefore screened out. This should be considered a preliminary study to establish a direct relationship with the host metabolic background and artemisinin resistance.

Gene expression of the liver of vaccination-protected mice in response to early patent infections of Plasmodium chabaudi blood-stage malaria

BACKGROUND

The role of the liver for survival of blood-stage malaria is only poorly understood. In experimental blood-stage malaria with Plasmodium chabaudi, protective vaccination induces healing and, thus, survival of otherwise lethal infections. This model is appropriate to study the role of the liver in vaccination-induced survival of blood-stage malaria.

METHODS

Female Balb/c mice were vaccinated with a non-infectious vaccine consisting of plasma membranes isolated in the form of erythrocyte ghosts from P. chabaudi-infected erythrocytes at week 3 and week 1 before infection with P. chabaudi blood-stage malaria. Gene expression microarrays and quantitative real-time PCR were used to investigate the response of the liver, in terms of expression of mRNA and long intergenic non-coding (linc)RNA, to vaccination-induced healing infections and lethal P. chabaudi malaria at early patency on day 4 post infection, when parasitized erythrocytes begin to appear in peripheral blood.

RESULTS

In vaccination-induced healing infections, 23 genes were identified to be induced in the liver by > tenfold at p < 0.01. More than one-third were genes known to be involved in erythropoiesis, such as Kel, Rhag, Ahsp, Ermap, Slc4a1, Cldn13 Gata1, and Gfi1b. Another group of > tenfold expressed genes include genes involved in natural cytotoxicity, such as those encoding killer cell lectin-like receptors Klrb1a, Klrc3, Klrd1, the natural cytotoxicity-triggering receptor 1 Ncr1, as well as the granzyme B encoding Gzmb. Additionally, a series of genes involved in the control of cell cycle and mitosis were identified: Ccnb1, Cdc25c, Ckap2l were expressed > tenfold only in vaccination-protected mice, and the expression of 22 genes was at least 100% higher in vaccination-protected mice than in non-vaccinated mice. Furthermore, distinct lincRNA species were changed by > threefold in livers of vaccination-protected mice, whereas lethal malaria induced different lincRNAs.

CONCLUSION

The present data suggest that protective vaccination accelerates the malaria-induced occurrence of extramedullary erythropoiesis, generation of liver-resident cytotoxic cells, and regeneration from malaria-induced injury in the liver at early patency, which may be critical for final survival of otherwise lethal blood-stage malaria of P. chabaudi.

Genome-wide association studies identified variants for taurine concentration in Japanese Black beef

We performed genome-wide association studies (GWAS) using the BovineSNP50 array to detect significant single nucleotide polymorphisms (SNPs) that may affect the concentration of 22 free amino acids and three peptides in Japanese Black beef cattle. A total of 574 Japanese Black cattle and 40,657 SNPs from the array were used for this study. Genome-wide significant SNPs were detected for β-alanine (three SNPs on chromosomes 22 and 29) and taurine (26 SNPs on chromosome 22). Importantly, the top two SNPs for taurine were highly significant (p = 6.2 × 10^-21 ), and the frequency of the increase-concentration allele (Q) for taurine was found to be 0.73. The Q allele frequency of this population was similar to that of the other unrelated Japanese Black cattle, but different from that of the other breeds. In addition, the significant SNPs were not associated with carcass traits or fatty acid compositions. Interestingly, the top three of the four most significant SNPs for taurine were located near solute carrier family 6, member 6 (SLC6A6), which is a membrane transporter for taurine. We also found two associated variants in the 5'-upstream region of SLC6A6; however, they were less significantly associated than the SNPs from the BovineSNP50 array.

A metabolomic analytical approach permits identification of urinary biomarkers for Plasmodium falciparum infection: a case-control study

BACKGROUND

Currently available diagnostic techniques of Plasmodium falciparum infection are not optimal for non-invasive, population-based screening for malaria. It was hypothesized that a mass spectrometry-based metabolomics approach could identify urinary biomarkers of falciparum malaria.

METHODS

The study used a case-control design, with cases consisting of 21 adults in central Ethiopia with a diagnosis of P. falciparum infection confirmed with microscopy, and 25 controls of adults with negative blood smears for malaria matched on age and sex. Urinary samples were collected from these individuals during presentation at the clinic, and a second sample was collected from both cases and controls 4 weeks later, after the cases had received anti-malarial medication. The urine samples were screened for small molecule urinary biomarkers, using mass spectrometry-based metabolomics analyses followed by multivariate analysis using principal component analysis and orthogonal partial least square-discriminant analysis. The chemical identity of statistically significant malaria biomarkers was confirmed using tandem mass spectrometry.

RESULTS

The urinary metabolic profiles of cases with P. falciparum infection were distinct from healthy controls. After treatment with anti-malarial medication, the metabolomic profile of cases resembled that of healthy controls. Significantly altered levels of 29 urinary metabolites were found. Elevated levels of urinary pipecolic acid, taurine, N-acetylspermidine, N-acetylputrescine and 1,3-diacetylpropane were identified as potential biomarkers of falciparum malaria.

CONCLUSION

The urinary biomarkers of malaria identified have potential for the development of non-invasive and rapid diagnostic test of P. falciparum infection.

Protective vaccination and blood-stage malaria modify DNA methylation of gene promoters in the liver of Balb/c mice

Epigenetic mechanisms such as DNA methylation are increasingly recognized to be critical for vaccination efficacy and outcome of different infectious diseases, but corresponding information is scarcely available for host defense against malaria. In the experimental blood-stage malaria Plasmodium chabaudi, we investigate the possible effects of a blood-stage vaccine on DNA methylation of gene promoters in the liver, known as effector against blood-stage malaria, using DNA methylation microarrays. Naturally susceptible Balb/c mice acquire, by protective vaccination, the potency to survive P. chabaudi malaria and, concomitantly, modifications of constitutive DNA methylation of promoters of numerous genes in the liver; specifically, promoters of 256 genes are hyper(=up)- and 345 genes are hypo(=down)-methylated (p < 0.05). Protective vaccination also leads to changes in promoter DNA methylation upon challenge with P. chabaudi at peak parasitemia on day 8 post infection (p.i.), when 571 and 1013 gene promoters are up- and down-methylated, respectively, in relation to constitutive DNA methylation (p < 0.05). Gene set enrichment analyses reveal that both vaccination and P. chabaudi infections mainly modify promoters of those genes which are most statistically enriched with functions relating to regulation of transcription. Genes with down-methylated promoters encompass those encoding CX3CL1, GP130, and GATA2, known to be involved in monocyte recruitment, IL-6 trans-signaling, and onset of erythropoiesis, respectively. Our data suggest that vaccination may epigenetically improve parts of several effector functions of the liver against blood-stage malaria, as, e.g., recruitment of monocyte/macrophage to the liver accelerated liver regeneration and extramedullary hepatic erythropoiesis, thus leading to self-healing of otherwise lethal P. chabaudi blood-stage malaria.

Differential miRNA Expression in the Liver of Balb/c Mice Protected by Vaccination during Crisis of Plasmodium chabaudi Blood-Stage Malaria

MicroRNAs are increasingly recognized as epigenetic regulators for outcome of diverse infectious diseases and vaccination efficacy, but little information referring to this exists for malaria. This study investigates possible effects of both protective vaccination and P. chabaudi malaria on the miRNome of the liver as an effector against blood-stage malaria using miRNA microarrays and quantitative PCR. Plasmodium chabaudi blood-stage malaria takes a lethal outcome in female Balb/c mice, but a self-healing course after immunization with a non-infectious blood-stage vaccine. The liver robustly expresses 71 miRNA species at varying levels, among which 65 miRNA species respond to malaria evidenced as steadily increasing or decreasing expressions reaching highest or lowest levels toward the end of the crisis phase on day 11 p.i. in lethal malaria. Protective vaccination does not affect constitutive miRNA expression, but leads to significant (p < 0.05) changes in the expression of 41 miRNA species, however evidenced only during crisis. In vaccination-induced self-healing infections, 18 miRNA-species are up- and 14 miRNA-species are down-regulated by more than 50% during crisis in relation to non-vaccinated mice. Vaccination-induced self-healing and survival of otherwise lethal infections of P. chabaudi activate epigenetic miRNA-regulated remodeling processes in the liver manifesting themselves during crisis. Especially, liver regeneration is accelerated as suggested by upregulation of let-7a-5p, let-7b-5p, let-7c-5p, let-7d-5p, let-7f-5p, let-7g-5p, let-7i-5p, miR-26a, miR-122-5p, miR30a, miR27a, and mir-29a, whereas the up-regulated expression of miR-142-3p by more than 100% is compatible with the view of enhanced hepatic erythropoiesis, possibly at expense of megakaryopoiesis, during crisis of P. chabaudi blood-stage malaria.

Anti-Eimeria activity of berberine and identification of associated gene expression changes in the mouse jejunum infected with Eimeria papillata

Plant-based natural products are promising sources for identifying novel agents with potential anti-Eimeria activity. This study explores possible effects of berberine on Eimeria papillata infections in the jejunum of male Swiss albino mice. Berberine chloride, when daily administered to mice during infection, impairs intracellular development and multiplication of E. papillata, evidenced as 60% reduction of maximal fecal output of oocysts on day 5 p.i. Concomitantly, berberine attenuates the inflammatory response, evidenced as decreased messenger RNA (mRNA) expression of IL-1β, IL-6, TNFα, IFNγ, and iNOS, as well as the oxidative stress response, evidenced as impaired increase in malondialdehyde, nitrate, and H2O2 and as prevented decrease in glutathione and catalase activity. Berberine also alters gene expression in the infected jejunum. On day 5 p.i., mRNA expression of 29 genes with annotated functions is more than 10-fold upregulated and that of 14 genes downregulated. Berberine downregulates the genes Xaf1, Itgb3bp, and Faim3 involved in apoptotic processes and upregulates genes involved in innate immune responses, as e.g., Colec11, Saa2, Klra8, Clec1b, and Crtam, especially the genes Cpa3, Fcer1a, and Mcpt1, Mcpt2, and Mcpt4 involved in mast cell activity. Additionally, 18 noncoding lincRNA species are differentially expressed more than 10-fold under berberine. Our data suggest that berberine induces hosts to exert anti-Eimeria activity by attenuating the inflammatory and oxidative stress response, by impairing apoptotic processes, and by activating local innate immune responses and epigenetic mechanisms in the host jejunum. Berberine has the potential as an anti-Eimeria food additive in animal farming.

Liver-inherent immune system: its role in blood-stage malaria

The liver is well known as that organ which is obligately required for the intrahepatocyte development of the pre-erythrocytic stages of the malaria-causative agent Plasmodium. However, largely neglected is the fact that the liver is also a central player of the host defense against the morbidity- and mortality-causing blood stages of the malaria parasites. Indeed, the liver is equipped with a unique immune system that acts locally, however, with systemic impact. Its main “antipodal” functions are to recognize and to generate effective immunoreactivity against pathogens on the one hand, and to generate tolerance to avoid immunoreactivity with “self” and harmless substances as dietary compounds on the other hand. This review provides an introductory survey of the liver-inherent immune system: its pathogen recognition receptors including Toll-like receptors (TLRs) and its major cell constituents with their different facilities to fight and eliminate pathogens. Then, evidence is presented that the liver is also an essential organ to overcome blood-stage malaria. Finally, we discuss effector responses of the liver-inherent immune system directed against blood-stage malaria: activation of TLRs, acute phase response, phagocytic activity, cytokine-mediated pro- and anti-inflammatory responses, generation of “protective” autoimmunity by extrathymic T cells and B-1 cells, and T cell-mediated repair of liver injuries mainly produced by malaria-induced overreactions of the liver-inherent immune system.

Testosterone persistently dysregulates hepatic expression of Tlr6 and Tlr8 induced by Plasmodium chabaudi malaria

Testosterone (T) is known to induce persistent susceptibility to Plasmodium chabaudi malaria. Pathogens recognizing Toll-like receptors (TLRs), though potentially important against malaria, have not yet been examined for their T-sensitivity. Here, we investigate effects of T and P. chabaudi on mRNA expression and promoter DNA methylation of Tlr1-9 genes in the liver of female C57BL/6 mice. These are treated with T or vehicle for 3 weeks, and then treatment is discontinued for 12 weeks, before challenging with P. chabaudi for 8 days. Our data reveal that T induces a 9.1-fold downregulation of Tlr6 mRNA and 6.3-fold upregulation of Tlr8 mRNA. Blood-stage infections induce significant increases in mRNA expression of Tlr1, 2, 4, 6, 7, and 8 varying between 2.5-fold and 21-fold in control mice. In T-pretreated mice, these Tlr genes are also significantly responsive to infections. However, the malaria-induced upregulations of the relative mRNA expressions of Tlr6 and Tlr8 are 5.6-fold higher and 6.5-fold lower in T-pretreated mice than in control mice. Infections induce a massive DNA down-methylation of the Tlr6 gene promoter in control mice, which is still more pronounced in T-pretreated mice, while significant changes are not detectable for the DNA methylation status of the Tlr8 promoter. Our data support the view that hepatic expression of Tlr6, but not that of Tlr8 is epigenetically controlled, and that the dysregulations of Tlr6 and Tlr8 critically contribute to T-induced persistent susceptibility to P. chabaudi malaria, possibly by dys-balancing responses of TLR6-mediated pathogen recognition and TLR8-mediated generation of anti-malaria "protective" autoimmunity.

The betaine/GABA transporter and betaine: roles in brain, kidney, and liver

The physiological roles of the betaine/GABA transporter (BGT1; slc6a12) are still being debated. BGT1 is a member of the solute carrier family 6 (the neurotransmitter, sodium symporter transporter family) and mediates cellular uptake of betaine and GABA in a sodium- and chloride-dependent process. Most of the studies of BGT1 concern its function and regulation in the kidney medulla where its role is best understood. The conditions here are hostile due to hyperosmolarity and significant concentrations of NH₄Cl and urea. To withstand the hyperosmolarity, cells trigger osmotic adaptation, involving concentration of a transcriptional factor TonEBP/NFAT5 in the nucleus, and accumulate betaine and other osmolytes. Data from renal cells in culture, primarily MDCK, revealed that transcriptional regulation of BGT1 by TonEBP/NFAT5 is relatively slow. To allow more acute control of the abundance of BGT1 protein in the plasma membrane, there is also post-translation regulation of BGT1 protein trafficking which is dependent on intracellular calcium and ATP. Further, betaine may be important in liver metabolism as a methyl donor. In fact, in the mouse the liver is the organ with the highest content of BGT1. Hepatocytes express high levels of both BGT1 and the only enzyme that can metabolize betaine, namely betaine:homocysteine –S-methyltransferase (BHMT1). The BHMT1 enzyme removes a methyl group from betaine and transfers it to homocysteine, a potential risk factor for cardiovascular disease. Finally, BGT1 has been proposed to play a role in controlling brain excitability and thereby represents a target for anticonvulsive drug development. The latter hypothesis is controversial due to very low expression levels of BGT1 relative to other GABA transporters in brain, and also the primary location of BGT1 at the surface of the brain in the leptomeninges. These issues are discussed in detail.

Membrane protein stability depends on the concentration of compatible solutes--a single molecule force spectroscopic study

Compatible solutes are small, uncharged, zwitter ionic, osmotically active molecules produced and accumulated by microorganisms inside their cell to counteract different kinds of environmental stress. They enhance protein stability without interfering with the metabolic pathways even at molar concentrations. In this paper, we report the stabilizing effects of compatible solutes, ectoine, betaine and taurine on membrane protein bacteriorhodopsin at different concentrations. Using atomic force microscopy based single molecule force spectroscopy the impact of the osmolytes was quantified by measuring the forces required to pull the protein out of the membrane and the change in the persistence lengths of the unfolded polypeptide chain. Increase in unfolding forces were observed, indicating the strengthening of intramolecular interactions, which are vital for protein stability. The decrease in persistence lengths was recorded and showed increasing tendencies of the polypeptide strand to coil up. Interestingly, it was revealed that these molecules have different stabilizing effects on protein unfolding at different concentrations. The results show that the unfolding of single protein provides insight to the structure-dynamic relationship between the protein and compatible solute molecules at sub-nanometer scale. This also helps to understand the molecular mechanism involved in protein stabilization by organic osmolytes.

Genome-wide screening identifies Plasmodium chabaudi-induced modifications of DNA methylation status of Tlr1 and Tlr6 gene promoters in liver, but not spleen, of female C57BL/6 mice

Epigenetic reprogramming of host genes via DNA methylation is increasingly recognized as critical for the outcome of diverse infectious diseases, but information for malaria is not yet available. Here, we investigate the effect of blood-stage malaria of Plasmodium chabaudi on the DNA methylation status of host gene promoters on a genome-wide scale using methylated DNA immunoprecipitation and Nimblegen microarrays containing 2,000 bp oligonucleotide features that were split into -1,500 to -500 bp Ups promoters and -500 to +500 bp Cor promoters, relative to the transcription site, for evaluation of differential DNA methylation. Gene expression was analyzed by Agilent and Affymetrix microarray technology. Challenging of female C57BL/6 mice with 10(6) P. chabaudi-infected erythrocytes resulted in a self-healing outcome of infections with peak parasitemia on day 8 p.i. These infections induced organ-specific modifications of DNA methylation of gene promoters. Among the 17,354 features on Nimblegen arrays, only seven gene promoters were identified to be hypermethylated in the spleen, whereas the liver exhibited 109 hyper- and 67 hypomethylated promoters at peak parasitemia in comparison with non-infected mice. Among the identified genes with differentially methylated Cor-promoters, only the 7 genes Pigr, Ncf1, Klkb1, Emr1, Ndufb11, and Tlr6 in the liver and Apol6 in the spleen were detected to have significantly changed their expression. Remarkably, the Cor promoter of the toll-like receptor Tlr6 became hypomethylated and Tlr6 expression increased by 3.4-fold during infection. Concomitantly, the Ups promoter of the Tlr1 was hypermethylated, but Tlr1 expression also increased by 11.3-fold. TLR6 and TLR1 are known as auxillary receptors to form heterodimers with TLR2 in plasma membranes of macrophages, which recognize different pathogen-associated molecular patterns (PAMPs), as, e.g., intact 3-acyl and sn-2-lyso-acyl glycosylphosphatidylinositols of P. falciparum, respectively. Our data suggest therefore that malaria-induced epigenetic fine-tuning of Tlr6 and Tlr1 through DNA methylation of their gene promoters in the liver is critically important for initial recognition of PAMPs and, thus, for the final self-healing outcome of blood-stage infections with P. chabaudi malaria.

Testosterone-induced persistent susceptibility to Plasmodium chabaudi malaria: long-term changes of lincRNA and mRNA expression in the spleen

Testosterone (T) is known to induce persistent susceptibility to blood-stage malaria of Plasmodium chabaudi in otherwise resistant female C57BL/6 mice, which is associated with permanent changes in mRNA expression of the liver. Here, we investigate the spleen as the major effector against blood-stage malaria for any possible T-induced long-term effects on lincRNA and mRNA expression. Female C57BL/6 mice were treated with T for 3 weeks, then T was withdrawn for 12 weeks before challenging with P. chabaudi. LincRNA and mRNA expression was examined after 12 weeks of T-withdrawal and after subsequent infections using Agilent whole mouse genome oligo microarrays. Our data show for the first time long-term effects of T on lincRNA expression evidenced directly as persistent changes after T-withdrawal for 12 weeks and indirectly as altered responsiveness of expression to P. chabaudi infections. There are 3 lincRNA-species upregulated and 10 lincRNAs downregulated by more than 2-fold (p<0.01). In addition, 11 and 10 mRNAs are persistently up- and downregulated by T, respectively. These changes remain not sustained during infections at peak parasitemia, when 15 other lincRNAs and 9 other mRNAs exhibit an altered expression. The only exception is the Tnk1-mRNA encoding the non-receptor tyrosine kinase 1 that is persistently downregulated by 0.34-fold after T-withdrawal and that becomes upregulated by 5.9-fold upon infection at peak parasitemia, suggesting an involvement of tyrosine phosphorylation by Tnk1 in mediating long-term effects of T in the spleen. The T-induced changes in splenic mRNA expression are totally different to those previously observed in the liver. Collectively, our data support the view that T induces long-term organ-specific changes in both lincRNA and mRNA expression, that presumably contribute to organ-specific dysfunctions upon infection with blood-stage malaria of P. chabaudi.

Implication of intestinal VDR deficiency in inflammatory bowel disease

BACKGROUND

To investigate the function of the intestinal Vdr gene in inflammatory bowel disease (IBD), in conjunction with the discovery of possible metabolic markers for IBD using intestine-specific Vdr knockout mice.

METHODS

Vdr(ΔIEpC) mice were generated, phenotyped and treated with a time-course of 3% dextran sulfate sodium (DSS) to induce colitis. Colitis was diagnosed by evaluating clinical symptoms and intestinal histopathology. Gene expression analysis was carried out. In addition, metabolic markers of IBD were explored by metabolomics.

RESULTS

Vdr(ΔIEpC) mice showed abnormal body size, colon structures and feces color. Calcium, collagen, and intestinal proliferation-related gene expression were all decreased, and serum alkaline phosphatase was highly increased. In the acute model which was treated with 3% DSS for six days, Vdr(ΔIEpC) mice showed a high score of IBD symptoms; enlarged mucosal layer and damaged muscularis layer. In the recovery experiment model, where mice were treated with 3% DSS for four days and water for three days, Vdr(ΔIEpC) mice showed a high score of IBD symptoms; severe damage of mucosal layer and increased expression of genes encoding proinflammatory cytokines. Feces metabolomics revealed decreased concentrations of taurine, taurocholic acid, taurodeoxycholic acid and cholic acid in Vdr(ΔIEpC) mice.

CONCLUSIONS

Disruption of the intestinal Vdr gene showed phenotypical changes that may exacerbate IBD. These results suggest that VDR may play an important role in IBD.

GENERAL SIGNIFICANCE

VDR function has been implicated in IBD. This is of value for understanding the etiology of IBD and for development of diagnostic biomarkers for IBD.

Physiology and pathophysiology of eryptosis

SUMMARY

Suicidal erythrocyte death (eryptosis) is characterized by cell shrinkage, cell membrane blebbing, and cell membrane phospholipid scrambling with phosphatidylserine exposure at the cell surface. Eryptotic cells adhere to the vascular wall and are rapidly cleared from circulating blood. Eryptosis is stimulated by an increase in cytosolic Ca(2)+ activity, ceramide, hyperosmotic shock, oxidative stress, energy depletion, hyperthermia, and a wide variety of xenobiotics and endogenous substances. Inhibitors of eryptosis include erythropoietin and nitric oxide. Enhanced eryptosis is observed in diabetes, renal insufficiency, hemolytic uremic syndrome, sepsis, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, beta-thalassemia, glucose-6-phosphate dehydrogenase-(G6PD) deficiency, hereditary spherocytosis, paroxysmal nocturnal hemoglobinuria, Wilson's disease, myelodysplastic syndrome, and phosphate depletion. Eryptosis is further enhanced in gene-targeted mice with deficient annexin 7, cGMP-dependent protein kinase type I (cGKI), AMP-activated protein kinase (AMPK), anion exchanger 1 (AE1), adenomatous polyposis coli (APC), and Klotho, as well as in mouse models of sickle cell anemia and thalassemia. Decreased eryptosis is observed in mice with deficient phosphoinositide-dependent kinase 1 (PDK1), platelet activating factor (PAF) receptor, transient receptor potential channel 6 (TRPC6), janus kinase 3 (JAK3), and taurine transporter (TAUT). Eryptosis may be a useful mechanism to remove defective erythrocytes prior to hemolysis. Excessive eryptosis may, however, compromise microcirculation and lead to anemia.

Metabolic fingerprints of serum, brain, and liver are distinct for mice with cerebral and noncerebral malaria: a ¹H NMR spectroscopy-based metabonomic study

Cerebral malaria (CM) is a life-threatening disease in humans caused by Plasmodium falciparum, leading to high mortality. Plasmodium berghei ANKA (PbA) infection in C57Bl/6 mice induces pathologic symptoms similar to that in human CM. However, experimental CM incidence in mice is variable, and there are no known metabolic correlates/fingerprints for the animals that develop CM. Here, we have used (1)H NMR-based metabonomics to investigate the metabolic changes in the mice with CM with respect to the mice that have noncerebral malaria (NCM) of the same batchmates with identical genetic backgrounds and infected simultaneously. The metabolic profile of the infected mice (both CM and NCM) was separately compared with the metabolite profile of uninfected control mice of same genetic background. The objective of this study was to search for metabolic changes/fingerprints of CM and identify the pathways that might be differentially altered in mice that succumbed to CM. The results show that brain, liver, and sera exhibit unique metabolic fingerprints for CM over NCM mice. Some of the major fingerprints are increased level of triglycerides, VLDL-cholesterol in sera of CM mice, and decreased levels of glutamine in the sera concomitant with increased levels of glutamine in the brain of the mice with CM. Moreover, glycerophosphocholine is decreased in both the brain and the liver of animals with CM, and myo-inositol and histamine are increased in the liver of CM mice. The metabolic fingerprints in brain, sera, and liver of mice with CM point toward perturbation in the ammonia detoxification pathway and perturbation in lipid and choline metabolism in CM specifically. The study helps us to understand the severity of CM over NCM and in unrevealing the specific metabolic pathways that are compromised in CM.

Organ-specific testosterone-insensitive response of miRNA expression of C57BL/6 mice to Plasmodium chabaudi malaria

Increasing evidence critically implicates miRNAs in the pathogenesis of diseases, but little is known in context with infectious diseases. This study investigates as to whether the testosterone-induced persistent susceptibility to blood-stage malaria of Plasmodium chabaudi coincides with changes in miRNA expression of the anti-malaria effectors sites spleen and liver. Female C57BL/6 mice were treated with vehicle or testosterone (T) for 3 weeks. Then, T treatment was discontinued for 12 weeks before challenge with 10(6) P. chabaudi-parasitized erythrocytes. The miRNA expression was examined after 12 weeks of T withdrawal and during infections at peak parasitemia on day 8 p.i. using miRXplore™ microarray technology. P. chabaudi infections induce an organ-specific response of miRNA expression. We can identify 25 miRNA species to be downregulated by more than 2-fold in the spleen and 169 miRNA species in the liver. Among these 194 miRNA species, there are 12 common miRNA species that are downregulated by 0.48-0.14-fold in both spleen and liver, which are miR-194, miR-192, miR-193A-3P, miR-145, miR-16, miR-99A, miR-99B, miR-15A, miR-152, let-7G, let-7B, and miR-455-3P. Only in the liver, there is an upregulation of the miR-142-5p by 2.5-fold and miR-342-3p by 5.1-fold. After 12 weeks of T withdrawal, the spleen exhibits only the miR-200A that is upregulated by 2.7-fold. In the liver, miR-376B, miR-493*, and miR-188-3P are upregulated by 2.4-fold, 2.2-fold, and 2.1-fold, respectively, and miR-347, miR-200A, and miR-200B are downregulated by approximately 0.4-fold. Upon infection, however, these changes are not sustained, i.e., the miRNA expressions of both spleen and liver of T-pretreated mice exhibit the same response to P. chabaudi malaria as that of vehicle-treated control mice. Our data suggest (1) that the P. chabaudi-induced downregulation of miRNA expression in spleen and liver is required to allow the upregulation of their numerous target genes in response to infection, and (2) that the T-induced persistent susceptibility to P. chabaudi does not affect the responsiveness of miRNA expression in spleen and liver to blood-stage malaria.

Cutting edge: Inhibition of IL-6 trans-signaling protects from malaria-induced lethality in mice

Circulating IL-6 levels correlate with the severity of blood-stage malaria in humans and mouse models, but the impact of IL-6 classic signaling through membrane IL-6Rα, as well as IL-6 trans-signaling through soluble IL-6Rα, on the outcome of malaria has remained unknown. In this study, we created IL-6Rα-deficient mice that exhibit a 50% survival of otherwise lethal blood-stage malaria of the genus Plasmodium chabaudi. Inducing IL-6 trans-signaling by injection of mouse recombinant soluble IL-6Rα in IL-6Rα-deficient mice restores the lethal outcome to malaria infection. In contrast, inhibition of IL-6 trans-signaling via injection of recombinant sGP130Fc protein in control mice results in a 40% survival rate. Our data demonstrate that IL-6 trans-signaling, rather than classic IL-6 signaling, contributes to malaria-induced lethality in mice, preceded by an increased inflammatory response. Therefore, inhibition of IL-6 trans-signaling may serve as a novel promising therapeutic basis to combat malaria.

A genome wide association scan of bovine tuberculosis susceptibility in Holstein-Friesian dairy cattle

Background

Bovine tuberculosis is a significant veterinary and financial problem in many parts of the world. Although many factors influence infection and progression of the disease, there is a host genetic component and dissection of this may enlighten on the wider biology of host response to tuberculosis. However, a binary phenotype of presence/absence of infection presents a noisy signal for genomewide association study.

Methodology/Principal Findings

We calculated a composite phenotype of genetic merit for TB susceptibility based on disease incidence in daughters of elite sires used for artificial insemination in the Irish dairy herd. This robust measure was compared with 44,426 SNP genotypes in the most informative 307 subjects in a genome wide association analysis. Three SNPs in a 65 kb genomic region on BTA 22 were associated (i.e. p<10⁻⁵, peaking at position 59588069, p = 4.02×10⁻⁶) with tuberculosis susceptibility.

Conclusions/Significance

A genomic region on BTA 22 was suggestively associated with tuberculosis susceptibility; it contains the taurine transporter gene SLC6A6, or TauT, which is known to function in the immune system but has not previously been investigated for its role in tuberculosis infection.

Testosterone response of hepatic gene expression in female mice having acquired testosterone-unresponsive immunity to Plasmodium chabaudi malaria

Blood-stage malaria of Plasmodium chabaudi is characterized by its responsiveness to testosterone (T): T suppresses development of protective immunity, whereas once acquired immunity is T-unresponsive. Here, we have analyzed the liver, a T target and lymphoid organ with anti-malaria activity, for its T-responsiveness of gene expression in immune mice. Using Affymetrix microarray technology, in combination with quantitative RT-PCR, we have identified (i) T-unresponsive expression of newly acquired mRNAs encoding diverse sequences of IgG- and IgM-antibodies, (ii) 24 genes whose expression has become T-unresponsive including those encoding the T(H)2 response promoting EHMT2 and the erythrocyte membrane protein band 7.2 STOM, (iii) T-unresponsive expression of mRNAs for the cytokines IL-1β, IL-6, TNFα, and IFNγ, as well as iNOS, which are even not inducible by infection, and (iv) 35 genes retaining their T-responsiveness, which include those encoding the infection-inducible acute phase proteins SAA1, SAA2, and ORM2 as well as those of liver metabolism which encode the T-downregulated female-prevalent enzymes CYP2B9, CYP2B13, CYP3A41, CYP7A1, and SULT2A2 and the T-upregulated male-prevalent enzymes CYP2D9, CYP7B1, UGT2B1, HSD3B2, HSD3B5, respectively. The mRNA of the latter T-metabolizing enzyme is even 5-fold increased by T, suggesting a decrease in the effective T concentrations in the liver of immune mice. Collectively, our data suggest that the liver, which has acquired a selective T-unresponsiveness of gene expression, contributes to the acquired T-unresponsive, antibody-mediated protective immunity to blood-stage malaria of P. chabaudi.

Inhibition of suicidal erythrocyte death by blebbistatin

Blebbistatin, a myosin II inhibitor, interferes with myosin-actin interaction and microtubule assembly. By influencing cytoskeletal dynamics blebbistatin counteracts apoptosis of several types of nucleated cells. Even though lacking nuclei and mitochondria, erythrocytes may undergo suicidal cell death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the cell surface. Triggers of eryptosis include energy depletion and osmotic shock, which enhance cytosolic Ca(2+) activity with subsequent Ca(2+)-sensitive cell shrinkage and cell membrane scrambling. The present study explored the effect of blebbistatin on eryptosis. Cell membrane scrambling was estimated from binding of annexin V to phosphatidylserine at the erythrocyte surface, cell volume from forward scatter in fluorescence-activated cell sorting analysis and cytosolic Ca(2+) concentration from Fluo3 fluorescence. Exposure to blebbistatin on its own (1-50 μM) did not significantly modify cytosolic Ca(2+) concentration, forward scatter, or annexin V binding. Glucose depletion (48 h) was followed by a significant increase of Fluo3 fluorescence and annexin V binding, effects significantly blunted by blebbistatin (Fluo3 fluorescence ≥ 25 μM, annexin V binding ≥ 10 μM). Osmotic shock (addition of 550 mM sucrose) again significantly increased Fluo3 fluorescence and annexin binding, effects again significantly blunted by blebbistatin (Fluo3 fluorescence ≥ 25 μM, annexin V binding ≥ 25 μM). The present observations disclose a novel effect of blebbistatin, i.e., an influence on Ca(2+) entry and suicidal erythrocyte death following energy depletion and osmotic shock.