Vaccination Accelerates Liver-Intrinsic Expression of Megakaryocyte-Related Genes in Response to Blood-Stage Malaria

Erythropoiesis and megakaryo-/thrombopoiesis occur in the bone marrow proceeding from common, even bipotent, progenitor cells. Recently, we have shown that protective vaccination accelerates extramedullary hepatic erythroblastosis in response to blood-stage malaria of Plasmodium chabaudi. Here, we investigated whether protective vaccination also accelerates extramedullary hepatic megakaryo-/thrombopoiesis. Female Balb/c mice were twice vaccinated with a non-infectious vaccine before infecting with 106 P. chabaudi-parasitized erythrocytes. Using gene expression microarrays and quantitative real-time PCR, transcripts of genes known to be expressed in the bone marrow by cells of the megakaryo-/thrombocytic lineage were compared in livers of vaccination-protected and unprotected mice on days 0, 1, 4, 8, and 11 p.i. Livers of vaccination-protected mice responded with expression of megakaryo-/thrombocytic genes faster to P. chabaudi than those of unvaccinated mice, evidenced at early patency on day 4 p.i., when livers exhibited significantly higher levels of malaria-induced transcripts of the genes Selp and Pdgfb (p-values < 0.0001), Gp5 (p-value < 0.001), and Fli1, Runx1, Myb, Mpl, Gp1ba, Gp1bb, Gp6, Gp9, Pf4, and Clec1b (p-values < 0.01). Together with additionally analyzed genes known to be related to megakaryopoiesis, our data suggest that protective vaccination accelerates liver-intrinsic megakaryo-/thrombopoiesis in response to blood-stage malaria that presumably contributes to vaccination-induced survival of otherwise lethal blood-stage 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.

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.

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.

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.

Protective Vaccination against Blood-Stage Malaria of Plasmodium chabaudi: Differential Gene Expression in the Liver of Balb/c Mice toward the End of Crisis Phase

Protective vaccination induces self-healing of otherwise fatal blood-stage malaria of Plasmodium chabaudi in female Balb/c mice. To trace processes critically involved in self-healing, the liver, an effector against blood-stage malaria, is analyzed for possible changes of its transcriptome in vaccination-protected in comparison to non-protected mice toward the end of the crisis phase. Gene expression microarray analyses reveal that vaccination does not affect constitutive expression of mRNA and lincRNA. However, malaria induces significant (p < 0.01) differences in hepatic gene and lincRNA expression in vaccination-protected vs. non-vaccinated mice toward the end of crisis phase. In vaccination-protected mice, infections induce up-regulations of 276 genes and 40 lincRNAs and down-regulations of 200 genes and 43 lincRNAs, respectively, by >3-fold as compared to the corresponding constitutive expressions. Massive up-regulations, partly by >100-fold, are found for genes as RhD, Add2, Ank1, Ermap, and Slc4a, which encode proteins of erythrocytic surface membranes, and as Gata1 and Gfi1b, which encode transcription factors involved in erythrocytic development. Also, Cldn13 previously predicted to be expressed on erythroblast surfaces is up-regulated by >200-fold, though claudins are known as main constituents of tight junctions acting as paracellular barriers between epithelial cells. Other genes are up-regulated by <100- and >10-fold, which can be subgrouped in genes encoding proteins known to be involved in mitosis, in cell cycle regulation, and in DNA repair. Our data suggest that protective vaccination enables the liver to respond to P. chabaudi infections with accelerated regeneration and extramedullary erythropoiesis during crisis, which contributes to survival of otherwise lethal blood-stage malaria.

Epigenetic modifications of gene promoter DNA in the liver of adult female mice masculinized by testosterone

Testosterone (T) is known to masculinize the female phenotype of the liver, evidenced as up- and down-regulated expressions of male- and female-predominant genes, respectively, involved in hepatic metabolism. This study is aimed at identifying epigenetic modifications of promoters of these differently expressed genes in the liver after masculinization by T of adult female C57BL/6 mice using methylated DNA immunoprecipitation and NimbleGen microarrays. Among the 17,354 promoters examined, 82 promoters in the liver have been identified to be significantly changed by T (p<0.05), with 47 and 35 promoters exhibiting increased and decreased DNA methylation, respectively. Most of these promoters display the changes of DNA methylation in their Ups-regions, which are between +500 and +2000 bp upstream from the transcription start site (TSS) of the genes. Less T-induced modifications have been detected in the Cor-regions of the promoters, i.e., +500 to -500 bp around the TSS. Only 13 and 7 Cor-promoters are hyper- and hypo-methylated, respectively, among which are 10 hyper- and 5 hypo-methylated promoters of genes with annotated functions. Surprisingly, the promoters are largely unmethylated in those genes whose expression has been previously found to be permanently deregulated by T in the liver, as e.g. the T-upregulated male-predominant genes Cyp7b1, Cyp2d9, Cyp4a10, Ugt2b1, Ugt2b38, Hsd3b5, Slco1a1 as well as the T-downregulated female-predominant genes Cyp2b9, Cyp2b13, Cyp3a41, Cyp3a44, Fmo3, Sult2a2, respectively. Though methylatable, the promoter DNA of Ar, Esr1, and Esr2 remained unaffected by T. However, T decreases DNA-methylation of the Cor-promoter region of Ddc encoding the AR-coactivator dopa decarboxylase. Among the identified 15 Cor-promoters of genes with annotated functions are also those of Defb43, Cst11, and Sele involved in innate immunity. Our data support the view that T may exert long-lasting epigenetic effects on functions of the liver-inherent immune system.

Dietary selenium in adjuvant therapy of viral and bacterial infections

Viral and bacterial infections are often associated with deficiencies in macronutrients and micronutrients, including the essential trace element selenium. In selenium deficiency, benign strains of Coxsackie and influenza viruses can mutate to highly pathogenic strains. Dietary supplementation to provide adequate or supranutritional selenium supply has been proposed to confer health benefits for patients suffering from some viral diseases, most notably with respect to HIV and influenza A virus (IAV) infections. In addition, selenium-containing multimicronutrient supplements improved several clinical and lifestyle variables in patients coinfected with HIV and Mycobacterium tuberculosis. Selenium status may affect the function of cells of both adaptive and innate immunity. Supranutritional selenium promotes proliferation and favors differentiation of naive CD4-positive T lymphocytes toward T helper 1 cells, thus supporting the acute cellular immune response, whereas excessive activation of the immune system and ensuing host tissue damage are counteracted through directing macrophages toward the M2 phenotype. This review provides an up-to-date overview on selenium in infectious diseases caused by viruses (e.g., HIV, IAV, hepatitis C virus, poliovirus, West Nile virus) and bacteria (e.g., M. tuberculosis, Helicobacter pylori). Data from epidemiologic studies and intervention trials, with selenium alone or in combination with other micronutrients, and animal experiments are discussed against the background of dietary selenium requirements to alter immune functions.

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.

Towards identifying novel anti-Eimeria agents: trace elements, vitamins, and plant-based natural products

Eimeriosis, a widespread infectious disease of livestock, is caused by coccidian protozoans of the genus Eimeria. These obligate intracellular parasites strike the digestive tract of their hosts and give rise to enormous economic losses, particularly in poultry, ruminants including cattle, and rabbit farming. Vaccination, though a rational prophylactic measure, has not yet been as successful as initially thought. Numerous broad-spectrum anti-coccidial drugs are currently in use for treatment and prophylactic control of eimeriosis. However, increasing concerns about parasite resistance, consumer health, and environmental safety of the commercial drugs warrant efforts to search for novel agents with anti-Eimeria activity. This review summarizes current approaches to prevent and treat eimeriosis such as vaccination and commercial drugs, as well as recent attempts to use dietary antioxidants as novel anti-Eimeria agents. In particular, the trace elements selenium and zinc, the vitamins A and E, and natural products extracted from garlic, barberry, pomegranate, sweet wormwood, and other plants are discussed. Several of these novel anti-Eimeria agents exhibit a protective role against oxidative stress that occurs not only in the intestine of Eimeria-infected animals, but also in their non-parasitized tissues, in particular, in the first-pass organ liver. Currently, it appears to be promising to identify safe combinations of low-cost natural products with high anti-Eimeria efficacy for a potential use as feed supplementation in animal farming.

Dietary selenium affects intestinal development of Eimeria papillata in mice

Here, we investigated the effect of the trace element selenium (Se) on course and outcome of Eimeria-paplllata-induced coccidiosis in mice. Male mice were fed on Se-adequate (0.15 ppm), Se-deficient, and Se-high diets (1.0 ppm) for 6 weeks. Mice were orally infected with 1,000 oocysts. The prepatent period lasts for 3 days, but the course of infections varied. At Se-adequate diet, the maximum fecal output of oocysts amounted to 68,300 ooccysts/g feces on day 5 p.i.. However, fecal shedding of oocysts was accelerated in mice on Se-deficient diet and occurred already on day 4 p.i.. By contrast, maximal shedding is impaired in mice on high-Se diet, which takes place on day 5 p.i., but with a decreased output of only 7,300 oocysts/g feces. Light microscopy reveals that all developmental stages are affected: meronts, micro- and macrogamonts, and developing oocysts are increased in comparison with mice fed on selenium-adequate diet. At high Se, the number of parasitic stages in the jejunum is substantially higher than at Se-deficient diet. Se does not affect the number of jejunal Alcian blue-stained goblet cells. Se deficiency increased the number of apoptotic cells in the jejunum. Substantially increased histological injury scores reveal more injuries in jejunum tissue infected by E. papillata. Our data indicate that high dietary Se exerts potential anticoccidial activity. This may be taken advantage of in control measures towards Eimeriosis as a feed additive, potentially alleviating the need for concomitantly utilized anti-coccidial drugs in the feed.

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.

Eimeria coecicola: spleen response of Oryctolagus cuniculus

The apicomplexan protozoon Eimeria coecicola is an infectious agent of intestinal coccidiosis in rabbits, causing severe injuries in the appendix as the final target, but also in the liver though not being a target. Here, we investigated the effect of E. coecicola on the spleen of the rabbit Oryctolagus cuniculus with respect to structure and gene expression using 2-color Agilent whole rabbit genome oligo-microarray technology in combination with quantitative PCR. At maximal fecal output of E. coecicola oocyts on day 7p.i., the spleen did not contain any parasites, but displayed moderate inflammatory changes evidenced as fused white pulp areas, diffuse appearance of the marginal zones, and increased number of macrophages in the red pulp, eventually resulting in an increased histological score. The infections induced 36 genes to be up-regulated and 156 genes to be down-regulated, among which were 139 genes encoding diverse regions of antibodies. The highest upregulated genes were those encoding granzyme H (10-fold), lim1 (10-fold), xanthine dehydrogenase (9-fold), whereas the downregulated genes could be majorly assigned to the immune response, as e.g. the genes encoding the macrophage cationic peptide-2 (5-fold). Quantitative PCR of genes encoding GZMH, XDH, HSD17B1, SULT3A1, SAA, BPI, MCP-2, and GST exhibited the same transcriptional level as that detected by microarray analysis. The E. coecicola-induced changes in gene expression of the spleen were totally different to those found previously in appendix and liver. Only the granzyme H gene became upregulated in all three organs. Our data indicate that the spleen, though not a final target of E. coecicola, responds to E. coecicola infections, suggesting that the spleen may be part of an orchestrated host defense against E. coecicola critically involving GZMH-expressing NK-cells.

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.

Note: A large aperture four-mirror reflective wave-plate for high-intensity short-pulse laser experiments

We report on a four-mirror reflective wave-plate system based on a phase-shifting mirror (PSM) for a continuous variation of elliptical polarization without changing the beam position and direction. The system presented and characterized here can replace a conventional retardation plate providing all advantages of a PSM, such as high damage-threshold, large scalability, and low dispersion. This makes reflective wave-plates an ideal tool for ultra-high power laser applications.

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.

Creating circularly polarized light with a phase-shifting mirror

We report on the performance of a system employing a multi-layer coated mirror creating circularly polarized light in a fully reflective setup. With one specially designed mirror we are able to create laser pulses with an ellipticity of more than ε = 98% over the entire spectral bandwidth from initially linearly polarized Titanium:Sapphire femtosecond laser pulses. We tested the homogeneity of the polarization with beam sizes of the order of approximately 10 cm. The damage threshold was determined to be nearly 400 times higher than for a transmissive quartz-wave plate which suggests applications in high intensity laser experiments. Another advantage of the reflective scheme is the absence of nonlinear effects changing the spectrum or the pulse-form and the scalability of coating fabrication to large aperture mirrors.

Liver response of rabbits to Eimeria coecicola infections

Intestinal coccidiosis of rabbits induced by E. coecicola causes enormous economic losses in rabbit farms. Here, we investigate the effect of E. coecicola on the liver of the rabbit Oryctolagus cuniculus. On day 7 p.i., fecal expulsion of E. coecicola oocysts is maximal and rabbits have lost approximately 25% of their weight. The liver, though not targeted by parasites, exhibits several signs of moderate inflammations, i.e., inflammatory cellular infiltrations around the central vein, dilatated blood sinusoids, increase in vacuolated hepatocytes, hypertrophic Kupffer cells, and lipid peroxidation as well as decreases in catalase and superoxide dismutase activities. Liver injuries are also indicated by an increase in blood plasma, by an increase in liver enzymes such as alanine transaminase, aspartate transaminase, alkaline phosphatase, and gamma glutamyl transferase, and a decrease in total protein and albumin. Circulating neutrophils have increased from 61% on day 0 p.i. to 71.3% on day 7 p.i., while lymphocytes are decreased from 37% to 26%. Agilent two-color oligo microarray technology, in combination with quantitative PCR, reveals that the expressions of 56 genes are upregulated and that of 22 genes are downregulated in the liver. The genes are largely involved in metabolism, calcium homeostasis, transport, and diverse signaling processes in the liver. In addition, numerous genes encoding for different regions of T-cell receptor as well as IgM, IgG, and IgA antibodies are both up- and downregulated in the liver by E. coecicola infections. The latter data suggest that the liver is not only 'passively' inflamed by intestinal infections with E. coecicola but rather is actively involved in the host defense against the intestinal Eimeria parasites.

Testosterone-induced permanent changes of hepatic gene expression in female mice sustained during Plasmodium chabaudi malaria infection

Testosterone has been previously shown to induce persistent susceptibility to Plasmodium chabaudi malaria in otherwise resistant female C57BL/6 mice. Here, we investigate as to whether this conversion coincides with permanent changes of hepatic gene expression profiles. Female mice aged 10-12 weeks were treated with testosterone for 3 weeks; then, testosterone treatment was discontinued for 12 weeks before challenging with 10⁶ P. chabaudi-infected erythrocytes. Hepatic gene expression was examined after 12 weeks of testosterone withdrawal and after subsequent infection with P. chabaudi at peak parasitemia, using Affymetrix microarrays with 22 ,690 probe sets representing 14, 000 genes. The expression of 54 genes was found to be permanently changed by testosterone, which remained changed during malaria infection. Most genes were involved in liver metabolism: the female-prevalent genes Cyp2b9, Cyp2b13, Cyp3a41, Cyp3a44, Fmo3, Sult2a2, Sult3a1, and BC014805 were repressed, while the male-prevalent genes Cyp2d9, Cyp7b1, Cyp4a10, Ugt2b1, Ugt2b38, Hsd3b5, and Slco1a1 were upregulated. Genes encoding different nuclear receptors were not persistently changed. Moreover, testosterone induced persistent upregulation of genes involved in hepatocellular carcinoma such as Lama3 and Nox4, whereas genes involved in immune response such as Ifnγ and Igk-C were significantly decreased. Our data provide evidence that testosterone is able to induce specific and robust long-term changes of gene expression profiles in the female mouse liver. In particular, those changes, which presumably indicate masculinized liver metabolism and impaired immune response, may be critical for the testosterone-induced persistent susceptibility of mice to P. chabaudi malaria.

Testosterone-induced upregulation of miRNAs in the female mouse liver

Testosterone (T) regulates expression of protein-encoding genes directly through androgen receptor (AR) targeting androgen response element (ARE) in gene promoters or indirectly through non-genotropic mechanisms, but only limited information is available about T effects on expression of gene-regulatory non-coding miRNAs. Here, we investigate the effect of T on miRNA expression profiles in the female mouse liver using miRXplore microarrays and quantitative RT-PCR. T treatment for 3 weeks induced upregulation of the 6 miRNAs miR-22, miR-690, miR-122, let-7A, miR-30D and let-7D, reaching maximal expression at different time-points during T treatment. This upregulation was transient, i.e. it disappeared after T withdrawal for 12 weeks, and it was rather robust since it was not essentially affected by blood-stage infections with Plasmodium chabaudi malaria. In silico analysis revealed an ARE in the miR-122 promoter, while the other 5 miRNAs did not contain any ARE in their 2000bp promoters. The T-induced upregulation of the 6 miRNAs coincided with a downregulation of some of their target protein-encoding genes, the majority of which did incidentally not contain any ARE in their promoters. T treatment did not affect expression of AR and estrogen receptor beta (ERbeta), but significantly downregulated the miR-22 target genes ERalpha and aromatase. This downregulation is presumably not caused by T after its aromatase-mediated conversion to E(2) through ER, but rather by the T-induced upregulation of miR-22. Collectively, our data suggest that T can regulate expression of distinct miRNAs in vivo by both genotropic and non-genotropic mechanisms.

WITHDRAWN: Inhibition by toltrazuril of the recombinant cyclophilin ETCYP21 of Eimeria tenella

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

Deletion of the taurine transporter gene (taut) results in lowered levels of taurine, the most abundant amino acid in mammals. Here, we show that taut-/- mice have lost their ability to self-heal blood-stage infections with Plasmodium chabaudi malaria. All taut-/- mice succumb to infections during crisis, while about 90% of the control taut(+/+) mice survive. The latter retain unchanged taurine levels even at peak parasitemia. Deletion of taut, however, results in the lowering of circulating taurine levels from 540 to 264 micromol/liter, and infections cause additional lowering to 192 micromol/liter. Peak parasitemia levels in taut-/- mice are approximately 60% higher than those in taut(+/+) mice, an elevation that is associated with increased systemic tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) levels, as well as with liver injuries. The latter manifest as increased systemic ammonia levels, a perturbed capacity to entrap injected particles, and increased expression of genes encoding TNF-alpha, IL-1beta, IL-6, inducible nitric oxide synthase (iNOS), NF-kappaB, and vitamin D receptor (VDR). Autopsy reveals multiorgan failure as the cause of death for malaria-infected taut-/- mice. Our data indicate that taut-controlled taurine homeostasis is essential for resistance to P. chabaudi malaria. Taurine deficiency due to taut deletion, however, impairs the eryptosis of P. chabaudi-parasitized erythrocytes and expedites increases in systemic TNF-alpha, IL-1beta, and ammonia levels, presumably contributing to multiorgan failure in P. chabaudi-infected taut-/- mice.

Mechanisms of action of emodepside

The research of the class of cyclic octadepsipeptides started at the beginning of the 1990s. PF1022A, the starting material of emodepside, is a natural secondary metabolite of the fungus Mycelia sterilia, which belongs to the microflora of the leaves of Camellia japonica. PF1022A consists of four N-methyl-L-leucins, two D-Iactic acids and two D-phenyllactic acids, which build up a cyclic octadepsipeptide with an alternating L-D-L-configuration. Emodepside is a semisynthetic derivative of PF1022A, which contains a morpholine attached in para position at each of both D-phenyllactic acids. Emodepside is efficacious against a variety of gastrointestinal nematodes. Emodepside binds to a presynaptic latrophilin receptor in nematodes. The following presynaptic signal transduction occurs via activation of Gqalpha protein and phospholipase-Cbeta, which leads to mobilization of diacylglycerol (DAG). DAG then activates UNC-13 and synaptobrevin, two proteins which play an important role in presynaptic vesicle-functioning. This finally leads to the release of a currently unidentified transmitter. The transmitter (or modulator) exerts its effects at the postsynaptic membrane and induces a flaccid paralysis of the pharynx and the somatic musculature in nematodes.

Augmented particle trapping and attenuated inflammation in the liver by protective vaccination against Plasmodium chabaudi malaria

BACKGROUND

To date all efforts to develop a malaria vaccine have failed, reflecting the still fragmentary knowledge about protective mechanisms against malaria. In order to evaluate if vaccination changes responses of the anti-malaria effectors spleen and liver to blood stage malaria, BALB/c mice succumbing to infection with Plasmodium chabaudi were compared to those surviving after vaccination.

METHODS

Mice were vaccinated with host cell plasma membranes isolated from P. chabaudi-infected erythrocytes. Hepatic and splenic capacity to trap particulate material was determined after injection of fluorescent polystyrol beads. Hepatic gene expression was measured using real-time RT-PCR and Northern blotting.

RESULTS

Survival of BALB/c mice was raised from 0% to 80% and peak parasitaemia was decreased by about 30% by vaccination. Vaccination boosted particle trapping capacity of the liver during crisis when splenic trapping is minimal due to spleen 'closing'. It also attenuated malaria-induced inflammation, thus diminishing severe damages and hence liver failure. Vaccination increased hepatic IFN-gamma production but mitigated acute phase response. Vaccination has a complex influence on infection-induced changes in expression of hepatic nuclear receptors (CAR, FXR, RXR, and PXR) and of the metabolic enzymes Sult2a and Cyp7a1. Although vaccination decreased CAR mRNA levels and prevented Cyp7a1 suppression by the CAR ligand 1,2-bis [2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) on day 8 p.i., Sult2a-induction by TCPOBOP was restored.

CONCLUSION

These data support the view that the liver is an essential effector site for a vaccine against blood stage malaria: vaccination attenuates malaria-induced inflammation thus improving hepatic metabolic activity and particle trapping activity of the liver.

A possible ambivalent role for relaxin in human myometrial and decidual cells in vitro

PURPOSE

Based on the reported tocolytic action of the hormone relaxin (RLX) in rodents, locally produced in reproductive tissues and the corpus luteum in mammals, the present study aimed to evaluate the influence of RLX on contraction-mediating cyclooxygenases-1 and -2 (COX) and the contractile prostaglandin PGE(2) in human myometrial and decidual cells. Primary cultured cells were obtained from uteri and placentas of term and preterm women undergoing elective caesarean section.

METHODS

In vitro culture of primary myometrial and decidual cells, immunocytochemistry, reverse transcription and real-time PCR, Western blot, ELISA.

RESULTS

We demonstrate for the first time an activating effect of RLX for human COX-1 and COX-2 in primary myometrial and decidual cells in vitro.

CONCLUSIONS

These effects might potentially contribute to birth-associated induction of contractions in vivo.

Eimeria tenella: genomic organization and expression of an 89kDa cyclophilin

Though parasite cyclophilins are promising new drug targets, Eimeria tenella cyclophilins have not been characterized yet. Here, we describe an 89kDa cyclophilin, designated EtCYP89. It is expressed throughout the developmental cycle of E. tenella, both in the intracellular stages in chicken and in extracellular sporulated oocysts and sporozoites. The EtCYP89 protein contains two Ser-rich domains in its NH2-terminus separated by a His-rich stretch. WD40 repeats are localized in the central part of the protein followed by a cyclophilin domain at the COOH-terminus. Both protein and genomic organization of EtCyp89 are conserved in comparison with its ortholog TgCyp81.6 in Toxoplasma gondii, except for the absence of a Ser- and His-rich NH2-terminus in TgCYP81.6. In particular, those 13 residues are conserved which are responsible for binding the anti-coccidial drug cyclosporine A.

Malaria-suppressible expression of the anti-apoptotic triple GTPase mGIMAP8

The IMAP/IAN family of AIG1-like GTPases is conserved among vertebrates and angiosperm plants and has been postulated to regulate apoptosis, particularly in context with diseases such as cancer, diabetes, and infections. The human genes were recently renamed as gimap for GTPase of the immunity associated protein (GIMAP) family. Here we extend this new nomenclature to the murine gimap gene family. All gimap genes of the mouse are clustered on chromosome 6B with eight functional members and one pseudogene. The mGIMAP proteins contain one GTP-binding site and display molecular masses between 33 and 38 kDa except for the very unusual 77 kDa mGIMAP8 protein, which is the first characterized protein containing three GTP-binding domains. Northern blot analysis revealed expression of mgimap8 predominantly in the thymus. The low expression level observed in the spleen was further suppressed by Plasmodium chabaudi malaria. Confocal laser scanning microscopy demonstrated localization of mGIMAP8 at ER, Golgi, and mitochondria. Overexpression of mGIMAP8 could significantly impair anisomycin-induced activation of caspase 3. Our data support the view that mGIMAP8 exerts an anti-apoptotic effect in the immune system and is involved in responses to infections.

Massive destruction of malaria-parasitized red blood cells despite spleen closure

It is currently accepted that malaria-parasitized red blood cells (pRBC) are eliminated, like senescent erythrocytes, phagocytically by macrophages in the red pulp of the spleen. Here, however, we show that self-healing Plasmodium chabaudi malaria activates spleen closure in C57BL/6 mice. Confocal laser scanning microscopy revealed that spleen closing was manifested by elimination of entry into the red pulp of 3-microm polystyrol particles, pRBC, and nonparasitized red blood cells but not of bovine serum albumin. This spleen closure did not reflect a reduction in the number of phagocytic cells, as shown by flow cytometry, whereas marginal zone macrophages (MZM) were lost and red pulp macrophages entered the white pulp. Splenic trapping of pBRC was strongly reduced in the absence of MZM and marginal metallophilic macrophages (MMM), as it is in noninfected mice with a disrupted lymphotoxin beta receptor (LTbetaR(-/-)), and it was still significantly reduced when the number of MZM and MMM was diminished, as in tumor necrosis factor alpha-deficient (TNF-alpha(-/-)) mice. Moreover, mice deficient in TNF-alpha, tumor necrosis factor receptor I (TNFRI(-/-)), and LTbetaR exhibited progressive impairment in malaria-induced spleen closing. Treatment of C57BL/6 mice with TNF-alpha induced loss of MZM and spleen closing by about 20%. Our data indicate that TNF/TNFRI signaling is involved in regulating malaria-induced spleen closure, which is maximal during crisis, when parasitemia declines more than 100-fold. Consequently, the vast majority of pRBC cannot be destroyed by the spleen during crisis, suggesting that the known sophisticated sequestration system of Plasmodium parasites did not evolve to avoid splenic clearance.

Modulation of Leishmania donovani infection and cell viability by testosterone in bone marrow-derived macrophages: signaling via surface binding sites

Androgens can increase susceptibility toward numerous parasitic infections as well as modulate apoptosis of immune cells. According to the current view, androgens mediate immune cell activities not only through classical intracellular androgen receptors (AR), but also through membrane receptors on the cell surface. Here, using murine bone marrow-derived macrophages (BMMs), we examined the influence of testosterone on Leishmania donovani infection and cell viability in vitro as well as the possible mechanisms. Our data demonstrated that testosterone directly increased intramacrophage infection by L. donovani. In addition, testosterone decreased cell viability by way of apoptosis, accompanied by increased Fas, FasL, and Caspase-8 expression. However, these effects of testosterone could not be associated with the classical AR in BMMs since AR was not detectable using different experimental techniques. Instead, it was found that testosterone could bind to the surface of BMMs by the use of an impermeable testosterone-BSA-FITC in confocal laser scanning microscopy and flow cytometry. Collectively, our data indicated that the influence of testosterone on L. donovani infection and viability of BMMs was mediated through the binding sites of testosterone on cell surfaces, which provided a novel mode of direct action of testosterone on AR-free BMMs.

Deletion of LTbetaR augments male susceptibility to Plasmodium chabaudi

SUMMARY Disruption of the lymphotoxin beta receptor (LTbetaR) gene has been shown to result in enhanced resistance of female mice to blood-stage Plasmodium chabaudi malaria. Here, we investigate the effect of LTbetaR deletion on host defence of males. In contrast to females, male LTbetaR(-/-) mice do not exhibit any increase in resistance. Conversely, they are even more susceptible than wild-type C57BL/6 mice, which becomes evident after lowering circulating levels of testosterone by castration, which makes C57BL/6 males resistant, whereas LTbetaR(-/-) remain susceptible. Gene-expression analysis using cDNA arrays revealed no differences in immunological responses in spleen of malaria-resistant female and malaria-susceptible castrated male LTbetaR(-/-) mice. In the liver, however, expression levels of plasminogen activator inhibitor PAI1, chemokine CXCL10, dual specificity phosphatase DUSP1, and hydroxysteroid-specific sulfotransferases Sult2a1/2 were decreased 6- to 85-fold in susceptible castrated male LTbetaR(-/-) mice in comparison to resistant female LTbetaR(-/-) mice at maximal parasitaemia, as evidenced by Northern blot analyses. The present data support our previous view that the liver is involved in the combat against malarial blood stages and that down-regulation of the genes DUSP1 and Sult2a1/2 signals dysregulation of protective liver responses, thus possibly contributing to male susceptibility of LTbetaR(-/-) mice.

Testosterone responsiveness of spleen and liver in female lymphotoxin β receptor-deficient mice resistant to blood-stage malaria

Disrupted signaling through lymphotoxin beta receptor (LTbetaR) results in severe defects of the spleen and even loss of all other secondary lymphoid tissues, making mice susceptible to diverse infectious agents. Surprisingly, however, we find that female LTbetaR-deficient mice are even more resistant to blood stages of Plasmodium chabaudi malaria than wild-type C57BL/6 mice. Higher resistance of LTbetaR-deficient mice correlates with an earlier onset of reticulocytosis, and the period of anemia is shorter. After surviving fulminant parasitemias of about 35%, mice develop long-lasting protective immunity against homologous rechallenge, with both spleen and liver acting as anti-malaria effectors. Testosterone suppresses resistance, i.e. all mice succumb to infections during or shortly after peak parasitemia. At peak parasitemia, testosterone does not essentially affect cellularity and apoptosis in the spleen, but aggravates liver pathology in terms of increased cell swelling, numbers of apoptotic and binucleated cells and reduced serum alkaline phosphatase levels, and conversely, reduces inflammatory lymphocytic infiltrates in the liver. In the spleen, hybridization of cDNA arrays identified only a few testosterone-induced changes in gene expression, in particular upregulation of INFgamma and IFN-regulated genes. By contrast, a much larger number of testosterone-affectable genes was observed in the liver, including genes involved in regulation of the extracellular matrix, in chemokine and cytokine signaling, and in cell cycle control. Collectively, our data suggest that testosterone dysregulates the inflammatory response in spleen and liver during their differentiation to anti-malaria effectors in malaria-resistant female LTbetaR-deficient mice, thus contributing to the testosterone-induced lethal outcome of malaria.

Comparative analysis of the human gimap gene cluster encoding a novel GTPase family

There is a growing family of novel GTPases conserved among higher plants and vertebrates, abbreviated as AIG1, IAP, IMAP, and IAN, respectively. Here, we comparatively analyze the human gene family encoding GTPases of the immunity-associated protein family recently re-termed GIMAP. Chromosome 7q36.1 contains, within 300 kb, a gimap gene cluster with seven functional genes and one pseudogene (hgimap3). The six genes hgimap1, hgimap2, hgimap4, hgimap5, hgimap6, and hgimap7 encode 33-46 kDa proteins with one GTP-binding domain, whereas hgimap8 encodes a very unusual 75-kDa protein with three GTP-binding domains. All hgimap genes except hgimap2 have orthologs in the mouse. Major expression sites of hgimap mRNAs are the spleen and lymph nodes, but also other organs such as muscle, heart, placenta, and digestive tract display detectable hgimap mRNA levels. The proteins hGIMAP4 and hGIMAP7 can be localized at ER and Golgi apparatus, but not in mitochondria, lysosomes and nuclei. All hgimap genes were expressed at very low levels-if at all-in diverse cancer cell lines. Our data support the view that the GIMAP proteins are involved in the control of cell survival not only in cells of the immune system as commonly anticipated.

Testosterone suppresses protective responses of the liver to blood-stage malaria

Testosterone induces a lethal outcome in otherwise self-healing blood-stage malaria caused by Plasmodium chabaudi. Here, we examine possible testosterone effects on the antimalaria effectors spleen and liver in female C57BL/6 mice. Self-healing malaria activates gating mechanisms in the spleen and liver that lead to a dramatic reduction in trapping activity, as measured by quantifying the uptake of 3-mum-diameter fluorescent polystyrol particles. However, testosterone delays malaria-induced closing of the liver, but not the spleen. Coincidently, testosterone causes an approximately 3- to 28-fold depression of the mRNA levels of nine malaria-responsive genes, out of 299 genes tested, only in the liver and not in the spleen, as shown by cDNA arrays and Northern blotting. Among these are the genes encoding plasminogen activator inhibitor (PAI1) and hydroxysteroid sulfotransferase (STA2). STA2, which detoxifies bile acids, is suppressed 10-fold by malaria and an additional 28-fold by testosterone, suggesting a severe perturbation of bile acid metabolism. PAI1 is protective against malaria, since disruption of the PAI1 gene results in partial loss of the ability to control the course of P. chabaudi infections. Collectively, our data indicate that the liver rather than the spleen is a major target organ for testosterone-mediated suppression of resistance against blood-stage malaria.

Genomic organization of the cadmium-inducible tandem repeat 25-kDa metallothionein of the oligochaete worm Enchytraeus buchholzi

The terrestric oligochaete worm Enchytraeus buchholzi survives in cadmium (Cd)-polluted environments by aid of its Cd-inducible 25 kDa cysteine-rich protein (CRP). Here, we analyze promoter and structure of the crp gene and compare its relationship to MT genes. The crp gene, approximately 12 kbp long, consists of 10 exons with exons 2 to 9 encoding eight almost identical repeats of predominantly 31 amino acids of the CRP. The introns of the crp gene contain various repetitive elements including retrotransposon-like sequences. The 683-bp promoter of the non-constitutive crp gene exhibits a much higher basal activity than the mouse MT-II promoter in HepG2 cells. Essential for crp promoter activity is the distal region (-683/-521) with a GC box and the proximal region (-308/-8) with the four MREa, b, c, d and AP-1, -2, -3 elements, whereas the central portion (-521/-309) with CAAT box, CRE and a XRE causes promoter repression. The TATA box-, MREc- and the AP-2, -3-containing region are required for high crp promoter activity. Our data support the view that the crp gene is a unique MT-gene and has evolved by exon duplications from a MT-like ancestral gene.

Rapid effects of androgens in macrophages

We investigated the existence of membrane receptors for testosterone (mAR) in mouse macrophages of the cell lines IC-21 and RAW 264.7 as well as their roles in nongenomic pathways, gene expression and cell functioning. Both cell lines lack intracellular androgen receptors (iARs) and respond to testosterone with rapid rises in [Ca2+]i. These rises in [Ca2+]i can neither be inhibited by iAR- nor by iER blockers, but are rather mediated through mAR. Pharmacological approaches suggest that the mAR belongs to the class of membrane receptors which are coupled to phospholipase C via pertussis toxin (PTX) sensitive G-proteins. The mAR can be localized as specific surface binding sites for testosterone-BSA-FITC by confocal laser scanning microscopy (CLSM)and flow cytometry, and are characterized by their agonist-sequestrability. In order to examine a possible role of the testosterone-induced rise in [Ca2+]i on gene expression, a c-fos promoter reporter gene construct was transfected into RAW 264.7 macrophages. The increase in [Ca2+]i induced by testosterone cannot significantly activate the c-fos promoter directly. Also, no significant activation of ERK1/2, JNK/SAPK and p38 can be observed following testosterone-stimulation alone. However, testosterone-induced rises in [Ca2+]i do have specific effects on gene expression in context with lipopolysaccharide (LPS)-induced genotropic signaling: testosterone specifically down-regulates LPS-induced activation of c-fos promoter, p38 MAPK and NO production. In fetal calf serum (FCS)-induced genotropic signaling, the situation is reversed, i.e. testosterone augments the activation of c-fos promoter and ERK1/2. Our studies demonstrate a cross-talk between the testosterone-induced nongenomic Ca2+ signaling and the genotropic signaling induced by LPS and FCS in macrophages.

Cyclooctadepsipeptides--an anthelmintically active class of compounds exhibiting a novel mode of action

There are three major classes of anthelmintics for veterinary use: the benzimidazoles/prebenzimidazoles, the tetrahydropyrimidines/imidazothiazoles, and the macrocyclic lactones. In nematodes, there are five targets for the existing anthelmintics: the nicotinergic acetylcholine receptor which is the target of tetrahydropyrimidines/imidazothiazoles and indirectly that of the acetylcholineesterase inhibitors; the GABA receptor which is the target of piperazine, the glutamate-gated chloride channel as the target of the macrocyclic lactones, and beta-tubulin as the target of prebenzimidazoles/benzimidazoles. All these anthelmintics are now in serious danger because of the worldwide spread of resistant nematodes in sheep, cattle, horses and pigs. The class of cyclooctadepsipeptides has entered the scene of anthelmintic research in the early 1990s. PF1022A, the first anthelmintically active member, is a natural compound from the fungus Mycelia sterilia that belongs to the microflora of the leaves of the Camellia japonica. PF1022A contains 4 N-Methyl-L-leucines, 2 D-lactic acids and 2-D-phenyllactic acids arranged as a cyclic octadepsipeptide with an alternating L-D-L-configuration. Emodepside is a semisynthetic derivative of PF1022A with a morpholine ring at each of the two D-phenyllactic acids in para position. The anthelmintic activity is directed against gastrointestinal nematodes in chicken, mice, rats, meriones, dogs, cats, sheep, cattle and horses. Moreover, emodepside is active against Trichinella spiralis larvae in muscles, microfilariae and preadult filariae and Dictyocaulus viviparus. PF1022A and emodepside are fully effective against benzimidazole-, levamisole or ivermectin-resistant nematodes in sheep and cattle. In Ascaris suum both cyclooctadepsipeptides lead to paralysis indicating a neuropharmacological action of these compounds. Using a PF1022A-ligand immunoscreening of a cDNA library from Haemonchus contortus a cDNA clone of 3569 base pairs could be identified. This clone codes for a novel 110 kDa heptahelical transmembrane receptor, named HC110R. Database- and phylogenetic analysis reveals that this receptor is a homolog to B0457.1 from Caenorhabditis elegans and has significant similarity to latrophilins from human, cattle and rat. HC110R is located in the plasma membrane and in lysosomes and endosomes. Alpha-latrotoxin, the poison of the black widow spider, binds at a 54 kDa aminoterminal fragment of HC110R. After binding a Ca2+-influx into HEK293 cells is induced which can be blocked by EGTA, Cd2+ or nifedipin. PF1022A or emodepside also bind to this 54 kDa aminoterminal region of HC110R and interact with the functional responses of alpha-latrotoxin. In C. elegans antibodies against the C-or N-terminus of HC110R bind to the B0457.1 protein located in the pharynx. Electrophysiological studies reveal that emodepside inhibits pharyngeal pumping of the nematodes in a concentration dependent way with an IC(50) value of about 4 nM. Thus, it is tempting to speculate that emodepside exerts its action on nematodes via a latrophilin-like receptor which might have an important regulatory function on pharyngeal pumping.

Testosterone inhibits apoptosis of Leishmania donovani-infected macrophages

AIM

Investigate the effect of the male sex hormone, testosterone (Te), on apoptosis of bone marrow derived macrophages (BMMs) from female C57BL/6j mice

METHODS

Propidium iodide (PI) staining and transmission electron microscopy (TEM) techniques were used to investigate apoptosis specific-morphological changes. BMMs derived from Te-treated mice and Oil-treated mice were challenged with Leishmania donovani (L. d.), Oligo-nucleosomal DNA were extracted 24 h post infection to detect apoptosis.

RESULTS

The removal of M-CSF from the medium could induce BMM apoptofsis. And the DNA fragmentation assay also indicated that: 1. there was no difference in the amount of apoptotic cells between Te and Oil group; 2. Te + L. d. group had significantly less dead cells than Oil + L. d. group demonstrating that Te could prevent apoptosis of macrophage infected with L. d. to a greater extent.

CONCLUSION

Te inhibits apoptosis of the macrophages infected with L. d., however, this inhibition did not occur in the macrophages uninfected with L. d. Te-induced macrophage apoptosis-inhibition may play an important role in Te-induced immunosuppression.

Developmental regulation of intracellular and surface androgen receptors in T cells

Increasing information indicates that testosterone actions on cells are mediated not only through the classical intracellular androgen receptor (iAR), but also through membrane androgen receptors (mAR) on cell surfaces. Here, we investigate the expression pattern of mAR and iAR in thymic T cells, which is compared with that of splenic T cells. Thymic T cells are testosterone-sensitive in vivo, i.e. treatment of female C57BL/10 mice with testosterone for 3 weeks decreased the total number of thymic T cells by approximately 90%. The percentage of CD4(-) CD8(-) T cells increased, whereas that of the subsequent CD4(+) CD8(+) T cells was diminished. Flow cytometry and confocal laser scanning microscopy (CLSM) with different anti-iAR antibodies localized iAR predominantly in the cytoplasm, but not on the surface of thymic T cells. The iAR are functionally active since the iAR are induced by testosterone to translocate from cytoplasm to nucleus, and they bind the testosterone analogue 3H-R1881 with high affinity (K(d) approximately 2.2 nM) and saturable capacity (approximately 10,000 binding sites per cell) as determined by Scatchard analysis. By contrast, the impeded ligand testosterone-BSA-FITC (T-BSA-FITC) did not bind to the surface of thymic T cells. In accordance, testosterone was unable to induce any rapid rise in the intracellular free Ca(2+) concentration of Fura-2 loaded thymocytes. This indicates that thymic T cells do not express any significant amounts of mAR. Conversely, splenic T cells express functionally active mAR, whereas their expressed iAR are not functional in the genomic pathway. Our results support the view of a delicately balanced developmental regulation of iAR and mAR in T cells.

Nongenomic testosterone calcium signaling. Genotropic actions in androgen receptor-free macrophages

Steroid hormones exert genotropic actions through members of the nuclear receptor family. Here, we have demonstrated genotropic actions of testosterone that are independent of intracellular androgen receptors (iAR). Through plasma membrane androgen receptors (mAR), testosterone induces a rapid rise in the intracellular free Ca(2+) concentration of iAR-free murine RAW 264.7 macrophages. This nongenomic testosterone signaling, which is independent of both iAR and estrogen receptors, does not in itself activate either the mitogen-activated protein kinase (MAPK) families ERK1/2, p38, and JNK/SAPK, the stably and transiently transfected c-fos promoter, or NO production. In the context of lipopolysaccharide (LPS) signaling, however, testosterone attenuates LPS activation of the c-fos promoter and NO production, which is abolished by the intracellular Ca(2+) chelator BAPTA. Testosterone also attenuates the LPS activation of p38 but not that of ERK1/2 and JNK/SAPK, and this attenuation is abrogated by BAPTA. Moreover, the p38 inhibitor, SB 203580, largely reduces LPS activation of the c-fos promoter and NO production, and the remaining levels are no longer regulated by testosterone. This study is the first to provide information on genotropic actions of mAR-mediated nongenomic testosterone Ca(2+) signaling by cross-talk with the LPS signaling pathway through p38 MAPK with impact on cell function.

B cells express intracellular but not surface receptors for testosterone and estradiol

Increasing evidence indicates the existence of membrane receptors for testosterone (mAR) and estradiol (mER) on the surface of cells, besides the classic intracellular androgen receptor (iAR) and estrogen receptors (iER). Here, we investigate the occurrence of sex steroid receptors in B cells isolated from the spleen of C57BL/10 mice using magnetic cell sorting. RT-PCR reveals the presence of iAR, iERalpha, but not iERbeta. Using different anti-iAR and anti-iER antibodies flow cytometry and confocal laser scanning microscopy (CLSM) localize iAR and iERalpha in the cytoplasm, which are translocatable to the nucleus upon incubation with testosterone (T) and 17beta-estradiol (E(2)). The surface of B cells is devoid of iAR and iERalpha and does not bind any T and E(2) conjugated to BSA-FITC as revealed by flow cytometry and CLSM. In accordance, T and E(2) are not able to induce any rapid rise in in the intracellular free Ca2+ concentration of Fura-2 loaded B cells. Our data indicate that B cells express neither mAR nor mER on their surfaces, in contrast to other major cells of the immune system such as T cells and macrophages.

Testosterone signaling in T cells and macrophages

This review summarizes data about non-genomic actions of testosterone on murine malaria, T cells and macrophages produced by our group during the last 15 years. In C57BL/10 mice, testosterone induces a lethal outcome of blood stage infections with Plasmodium chabaudi which normally takes a self-healing course controlled by genes of the H-2 complex and the non-H-2 background. This suppressive effect of testosterone is mediated neither via the classic intracellular androgen receptor (AR) response nor, after conversion of testosterone to estradiol, via the estrogen receptor. Testosterone acts non-genomically, i.e. through surface receptors, on murine T cells and macrophages, which becomes evident as a rapid rise in the intracellular free Ca(2+) concentration ([Ca(2+)](i)). In T cells, this rise reflects predominantly influx of extracellular Ca(2+), while it is predominantly due to release of Ca(2+) from intracellular Ca(2+)-stores in macrophages. The testosterone-induced rise in [Ca(2+)](i) of both macrophages and T cells is not inhibited by the AR-blocker cyproterone, and it is also inducible by the plasma membrane impermeable ligand testosterone-BSA. The surface receptors initiate a transcription-independent signaling pathway of testosterone. Currently, we are trying to isolate testosterone surface receptors and to investigate a possible cross-talk of non-genomic testosterone signaling with other genotropic signaling pathways.

Estradiol-induced nongenomic calcium signaling regulates genotropic signaling in macrophages

Estradiol (E(2)) exerts not only genotropic but also nongenomic actions through nuclear estrogen receptors (ER). Here, we provide a novel paradigm for nongenomic E(2) signaling independent of nuclear ER. E(2) induces a rapid rise in the intracellular free Ca(2+) concentration ([Ca(2+)](i)) through membrane estrogen receptors in murine RAW 264.7 macrophages. This E(2)-induced Ca(2+) signaling is not prevented by different ER blockers and cannot directly activate stably transfected c-fos promoter or the mitogen-activated protein kinases p38, ERK1/2, and SAPK/JNK, or NO production. However, the E(2)-induced rise in [Ca(2+)](i) specifically down-regulates the serum-stimulated activation of c-fos promoter and ERK1/2, and conversely, it specifically up-regulates lipopolysaccharide-stimulated activation of c-fos promoter, p38, and NO production. The E(2)-changed activation of c-fos promoter can be prevented by an intracellular Ca(2+) chelator. Our data indicate that E(2)-induced nongenomic Ca(2+) signaling through membrane ER is able to specifically modulate genotropic signaling pathways with impact on macrophage activation.