STAT6-mediated suppression of erythropoiesis in an experimental model of malarial anemia

Mouse Models for Unravelling Immunology of Blood Stage Malaria

Malaria comprises a spectrum of disease syndromes and the immune system is a major participant in malarial disease. This is particularly true in relation to the immune responses elicited against blood stages of Plasmodium-parasites that are responsible for the pathogenesis of infection. Mouse models of malaria are commonly used to dissect the immune mechanisms underlying disease. While no single mouse model of Plasmodium infection completely recapitulates all the features of malaria in humans, collectively the existing models are invaluable for defining the events that lead to the immunopathogenesis of malaria. Here we review the different mouse models of Plasmodium infection that are available, and highlight some of the main contributions these models have made with regards to identifying immune mechanisms of parasite control and the immunopathogenesis of malaria.

Association Between Blood PLT and RBC Related Indices and Disease Activity in Patients with Rheumatoid Arthritis

Background

Platelet (PLT) and red blood cell (RBC) have been demonstrated to play a critical role in inflammatory processes. This study aimed to evaluate the association of blood PLT and RBC related parameters with the disease activity in rheumatoid arthritis (RA) patients, and also to investigate the role of these indices in differentiating among RA patients with different disease activity.

Methods

Clinical data from RA patients were retrospectively analyzed. RA patients were divided into inactive group and active group according to DAS28-CRP. The relationship between blood PLT and RBC counts-related indices and DAS28-CRP was detected by Spearman correlation. ROC curve was used to assess the diagnostic value of these indices in differentiating active RA from inactive RA.

Results

Active RA patients exhibited higher level of PLT counts but significantly lower levels of RBC counts, hemoglobin (Hb), red blood cells-platelet ratio (RPR) and hemoglobin-platelet ratio (HPR) compared with inactive RA. PLT counts were positively but RBC counts, Hb, RPR and HPR were negatively related with DAS28-CRP.

Conclusion

Blood PLT and RBC related indices were significantly associated with RA disease activity. These indices may be used to distinguish active RA from inactive RA.

Challenges in forming inferences from limited data: a case study of malaria parasite maturation

Inferring biological processes from population dynamics is a common challenge in ecology, particularly when faced with incomplete data. This challenge extends to inferring parasite traits from within-host infection dynamics. We focus on rodent malaria infections (Plasmodium berghei), a system for which previous work inferred an immune-mediated extension in the length of the parasite development cycle within red blood cells. By developing a system of delay-differential equations to describe within-host infection dynamics and simulating data, we demonstrate the potential to obtain biased estimates of parasite (and host) traits when key biological processes are not considered. Despite generating infection dynamics using a fixed parasite developmental cycle length, we find that known sources of measurement bias in parasite stage and abundance data can affect estimates of parasite developmental duration, with stage misclassification driving inferences about extended cycle length. We discuss alternative protocols and statistical methods that can mitigate such misestimation.

Th1-Th2 Cross-Regulation Controls Early Leishmania Infection in the Skin by Modulating the Size of the Permissive Monocytic Host Cell Reservoir

The impact of T helper (Th) 1 versus Th2 immunity on intracellular infections is attributed to classical versus alternative activation of macrophages leading to resistance or susceptibility. However, observations in multiple infectious settings demonstrate deficiencies in mediators of Th1-Th2 immunity, which have paradoxical or no impact. We report that prior to influencing activation, Th1/Th2 immunity first controls the size of the permissive host cell reservoir. During early Leishmania infection of the skin, IFN-γ- or STAT6-mediated changes in phagocyte activation were counteracted by changes in IFN-γ-mediated recruitment of permissive CCR2⁺ monocytes. Monocytes were required for early parasite expansion and acquired an alternatively activated phenotype despite the Th1 dermal environment required for their recruitment. Surprisingly, STAT6 did not enhance intracellular parasite proliferation, but rather modulated the size and permissiveness of the monocytic host cell reservoir via regulation of IFN-γ and IL-10. These observations expand our understanding of the Th1-Th2 paradigm during infection.

Development of a model for anemia of inflammation that is relevant to critical care

BACKGROUND

Anemia of inflammation (AI) is common in critically ill patients. Although this syndrome negatively impacts the outcome of critical illness, understanding of its pathophysiology is limited. Also, new therapies that increase iron availability for erythropoiesis during AI are upcoming. A model of AI induced by bacterial infections that are relevant for the critically ill is currently not available. This paper describes the development of an animal model for AI that is relevant for critical care research.

RESULTS

In experiments with rats, the rats were inoculated either repeatedly or with a slow release of Streptococcus pneumoniae or Pseudomonas aeruginosa. Rats became ill, but their hemoglobin levels remained stable. The use of a higher dose of bacteria resulted in a lethal model. Then, we turned to a model with longer disease duration, using pigs that were supported by mechanical ventilation after inoculation with P. aeruginosa. The pigs became septic 12 to 24 h after inoculation, with a statistically significant decrease in mean arterial pressure and base excess, while heart rate tended to increase. Pigs needed resuscitation and vasopressor therapy to maintain a mean arterial pressure > 60 mmHg. After 72 h, the pigs developed anemia (baseline 9.9 g/dl vs. 72 h, 7.6 g/dl, p = 0.01), characterized by statistically significant decreased iron levels, decreased transferrin saturation, and increased ferritin. Hepcidin levels tended to increase and transferrin levels tended to decrease.

CONCLUSIONS

Using pathogens commonly involved in pulmonary sepsis, AI could not be induced in rats. Conversely, in pigs, P. aeruginosa induced pulmonary sepsis with concomitant AI. This AI model can be applied to study the pathophysiology of AI in the critically ill and to investigate the effectivity and toxicity of new therapies that aim to increase iron availability.

The Emerging Role of Pattern Recognition Receptors in the Pathogenesis of Malaria

Despite a global effort to develop an effective vaccine, malaria is still a significant health problem. Much of the pathology of malaria is immune mediated. This suggests that host immune responses have to be finely regulated. The innate immune system initiates and sets the threshold of the acquired immune response and determines the outcome of the disease. Yet, our knowledge of the regulation of innate immune responses during malaria is limited. Theoretically, inadequate activation of the innate immune system could result in unrestrained parasite growth. Conversely, hyperactivation of the innate immune system, is likely to cause excessive production of proinflammatory cytokines and severe pathology. Toll-like receptors (TLRs) have emerged as essential receptors which detect signature molecules and shape the complex host response during malaria infection. This review will highlight the mechanisms by which Plasmodium components are recognized by innate immune receptors with particular emphasis on TLRs. A thorough understanding of the complex roles of TLRs in malaria may allow the delineation of pathological versus protective host responses and enhance the efficacy of anti-malarial treatments and vaccines.

Integrative analysis associates monocytes with insufficient erythropoiesis during acute Plasmodium cynomolgi malaria in rhesus macaques

Background

Mild to severe anaemia is a common complication of malaria that is caused in part by insufficient erythropoiesis in the bone marrow. This study used systems biology to evaluate the transcriptional and alterations in cell populations in the bone marrow during Plasmodium cynomolgi infection of rhesus macaques (a model of Plasmodium vivax malaria) that may affect erythropoiesis.

Results

An appropriate erythropoietic response did not occur to compensate for anaemia during acute cynomolgi malaria despite an increase in erythropoietin levels. During this period, there were significant perturbations in the bone marrow transcriptome. In contrast, relapses did not induce anaemia and minimal changes in the bone marrow transcriptome were detected. The differentially expressed genes during acute infection were primarily related to ongoing inflammatory responses with significant contributions from Type I and Type II Interferon transcriptional signatures. These were associated with increased frequency of intermediate and non-classical monocytes. Recruitment and/or expansion of these populations was correlated with a decrease in the erythroid progenitor population during acute infection, suggesting that monocyte-associated inflammation may have contributed to anaemia. The decrease in erythroid progenitors was associated with downregulation of genes regulated by GATA1 and GATA2, two master regulators of erythropoiesis, providing a potential molecular basis for these findings.

Conclusions

These data suggest the possibility that malarial anaemia may be driven by monocyte-associated disruption of GATA1/GATA2 function in erythroid progenitors resulting in insufficient erythropoiesis during acute infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-2029-z) contains supplementary material, which is available to authorized users.

Hypercoagulability and Migraine

BACKGROUND

A growing body of literature suggests that migraineurs, particularly those with aura, have an increased risk for ischemic stroke, but not via enhanced atherosclerosis. The theory that micro-emboli induced ischemia provokes cortical spreading depression (ie, symptomatic aura) in migraineurs but transient ischemic attacks in others highlights a potential role for hypercoagulability as a link between migraine (with aura) and stroke.

AIM

Our objective is to summarize the literature evaluating the association of migraine with various acquired or inheritable thrombophilic states, including those related to elevated estrogen levels, endothelial activation and dysfunction, antiphospholipid antibodies (aPL), deficiency of coagulation inhibitors, and presence of certain genetic polymorphisms.

FINDINGS

Although definitive studies are lacking, a preponderance of available evidence links migraine, and especially aura, to increased levels of estradiol (eg, oral contraceptive pill [OCP] use, pregnancy), thrombo- and erythrocytosis, von Willebrand factor (vWF) antigen, fibrinogen, tissue plasminogen activator (tPA) antigen, and endothelial microparticles. Studies of a link to migraine are conflicting for aPL, homocysteine, Protein S, and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism. No association with migraine was found in meta-analyses of Factor V Leiden, and of prothrombin gene mutation. Within a large, young ischemic stroke sample, migraine with aura was associated with a thrombophilic state and with patent foramen ovale (PFO). In the non-stroke population, meta-analyses show an association of PFO and migraine with aura (MA), but two population-based studies do not support the link.

RECOMMENDATIONS

For persons with MA and (1) a personal history or family history of thrombosis, or (2) MRI evidence of micro-vascular ischemia or of stroke, an evaluation for hypercoagulability is warranted. In cases of MA alone, consider screening for markers of endothelial activation (eg, vWF, high sensitivity c-reactive protein [hs CRP], and fibrinogen). Rigorous management of other stroke risk factors is paramount, but efficacy of anti-thrombotic agents in the treatment of migraine is unproven. Closure of PFO is not routinely recommended based on negative randomized trials.

Effect of Promoter Polymorphisms on Cytokine Concentration in Preterm Breast Milk and Subsequent Infant Outcomes

BACKGROUND

Breast milk concentrations of immune components are variable between women and interleukin (IL) differences may be associated with infant outcomes. Molecular mechanisms for milk variability remain unknown.

OBJECTIVE

The aims were to (1) examine the relationship between maternal IL genotypes and milk concentrations of IL4, IL6, and IL10, (2) describe the trajectories of milk IL change, (3) examine whether maternal IL genotypes predict IL trajectories and/or average weekly IL concentration, and (4) examine if weekly IL levels and/or IL trajectories are associated with infant outcomes.

METHODS

Milk aliquots were collected from each feeding of mother's own milk and pooled weekly. DNA was extracted from 1 sample of each mother's breast milk whey (n = 64), and single nucleotide polymorphisms (SNPs) of IL genes were genotyped. Milk IL concentrations were measured and trajectory analysis examined IL milk change over time. Multivariate breast milk IL concentration analyses controlled for gestational age and prepregnancy body mass index. Multivariate infant outcome (n = 73) analyses controlled for gestational age and the ratio of human milk to total milk.

RESULTS

Trajectory analysis resulted in linear group shapes, with 2 distinct subgroups in IL6 and 3 subgroups in IL4 and IL10. Trajectory groups trended toward significance with calprotectin, intraventricular hemorrhage, and blood transfusions. Multivariate analyses resulted in trending associations between maternal SNPs and subsequent IL6 and IL10 milk levels. There was a trending relationship between IL milk levels and both fecal calprotectin and intraventricular hemorrhage.

CONCLUSION

Maternal IL SNPs may affect IL breast milk levels and IL milk levels may be associated with infant outcomes.

A STAT6 Intronic Single-Nucleotide Polymorphism is Associated with Clinical Malaria in Ghanaian Children

Malaria pathogenesis may be influenced by IgE responses and cytokine cross-regulation. Several mutations in the IL-4/STAT6 signaling pathway can alter cytokine cross-regulation and IgE responses during a Plasmodium falciparum malarial infection. This study investigated the relationship between a STAT6 intronic single-nucleotide polymorphism (rs3024974), total IgE, cytokines, and malaria severity in 238 Ghanaian children aged between 0.5 and 13 years. Total IgE and cytokine levels were measured by ELISA, while genotyping was done by polymerase chain reaction-restriction fragment length polymorphism (RFLP). Compared with healthy controls, heterozygosity protected against clinical malaria: uncomplicated malaria (odds ratios [OR] = 0.13, P < 0.001), severe malarial anemia (OR = 0.18, P < 0.001), and cerebral malaria (OR = 0.39, P = 0.022). Levels of total IgE significantly differed among malaria phenotypes (P = 0.044) and rs3024974 genotypes (P = 0.037). Neither cytokine levels nor IL-6/IL-10 ratios were associated with malaria phenotypes or rs3024974 genotypes. This study suggests a role for rs3024974 in malaria pathogenesis and offers further insights into an IL-4/STAT6 pathway mutation in malaria pathogenesis.

Correlation between deletion of the CDKN2 gene and tyrosine kinase inhibitor resistance in adult Philadelphia chromosome-positive acute lymphoblastic leukemia

BACKGROUND

Frequency relapses are common in Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) following tyrosine kinase inhibitors (TKIs). CDKN2A/B is believed to contribute to this chemotherapy resistance.

METHODS

To further investigate the association between CDKN2 status and TKI resistance, the prevalence of CDKN2 deletions and its correlation with a variety of clinical features was assessed in 135 Ph-positive ALL patients using interphase fluorescence in situ hybridization (I-FISH).

RESULTS

Results showed that no difference occurred between patients with CDKN2 deletion (44/135) and wild-type patients in sex, age, and complete remission (CR) rate following induction chemotherapy combined with tyrosine kinase inhibitors (TKIs). However, CDKN2 deletion carriers demonstrated higher white blood cell (WBC) count, enhanced rates of hepatosplenomegaly (P = 0.006), and upregulation of CD20 expression (P = 0.001). Moreover, deletions of CDKN2 resulted in lower rates of complete molecular response (undetectable BCR/ABL), increased cumulative incidence of relapse, short overall survival (OS), and disease-free survival (DFS) time (P < 0.05) even though these patients received chemotherapy plus TKIs followed by allogenic hematopoietic stem cell transplantation (Allo-HSCT). In the case of 44 patients who presented with CDKN2 deletion, 18 patients were treated with dasatinib treatment, and another 26 patients were treated with imatinib therapy, and our study found that there were no differences associated with OS (P = 0.508) and DFS (P = 0.555) between the two groups.

CONCLUSIONS

CDKN2 deletion is frequently acquired during Ph-positive ALL progression and serves as a poor prognostic marker of long-term outcome in Ph-positive ALL patients with CDKN2 deletion even after the second-generation tyrosine kinase inhibitor treatment.

Plasmodium products contribute to severe malarial anemia by inhibiting erythropoietin-induced proliferation of erythroid precursors

Low reticulocytosis, indicating reduced red blood cell (RBC) output, is an important feature of severe malarial anemia. Evidence supports a role for Plasmodium products, especially hemozoin (Hz), in suppressed erythropoiesis during malaria, but the mechanism(s) involved remains unclear. Here, we demonstrated that low reticulocytosis and suppressed erythropoietin (Epo)-induced erythropoiesis are features of malarial anemia in Plasmodium yoelii- and Plasmodium berghei ANKA-infected mice, similar to our previous observations in Plasmodium chabaudi AS-infected mice. The magnitude of decreases in RBC was a reflection of parasitemia level, but low reticulocytosis was evident despite differences in parasitemia, clinical manifestation, and infection outcome. Schizont extracts and Hz from P. falciparum and P. yoelii and synthetic Hz suppressed Epo-induced proliferation of erythroid precursors in vitro but did not inhibit RBC maturation. To determine whether Hz contributes to malarial anemia, P. yoelii-derived or synthetic Hz was administered to naive mice, and the development of anemia, reticulocytosis, and RBC turnover was determined. Parasite-derived Hz induced significant decreases in RBC and increased RBC turnover with compensatory reticulocytosis, but anemia was not as severe as that in infected mice. Our findings suggest that parasite factors, including Hz, contribute to severe malarial anemia by suppressing Epo-induced proliferation of erythroid precursors.

Novel therapeutic strategies in adult acute lymphoblastic leukemia--a focus on emerging monoclonal antibodies

The outcomes in adult B-cell acute lymphoblastic leukemia (ALL) remain inferior to those achieved in pediatric populations. Targeted therapy with monoclonal antibodies may improve outcomes in adult B-cell ALL without significant additive toxicity. Rituximab is the best known monoclonal antibody and is routinely used in combination chemo-immunotherapy for treatment of adult B-cell ALL and Burkitts leukemia. A number of other monoclonal antibodies are currently under investigation for treatment of adult B-cell ALL including unconjugated antibodies (eg., ofatumumab, alemtuzumab and epratuzumab), antibodies conjugated to cytotoxic agents (eg., inotuzumab ozogamycin and SAR3419), antibodies conjugated to toxins such Pseudomonas or Diptheria toxins (eg., BL22 and moxetumomab pasudotox), and T-cell engaging bi-specific antibodies that redirect cytotoxic T lymphocytes to lyse target ALL cells (eg., blinatumomab). In this article we review the therapeutic implications, current status and results of monoclonal antibody-based therapy in adult B-cell ALL.

Interleukin (IL)-13 promoter polymorphisms (-7402 T/G and -4729G/A) condition susceptibility to pediatric severe malarial anemia but not circulating IL-13 levels

In holoendemic Plasmodium falciparum transmission areas such as western Kenya, severe malarial anemia [SMA, hemoglobin (Hb) < 6.0 g/dL, with any density parasitemia] is the most common clinical manifestation of severe malaria resulting in high rates of pediatric morbidity and mortality in these regions. Previous studies associated interleukin (IL)-13 with pathogenesis of different infectious diseases, including P. falciparum malaria. However, the functional roles of polymorphic variants within the IL-13 promoter in conditioning susceptibility to SMA remain largely unexplored. As such, the association between the IL-13 variants -7402 T/G (rs7719175) and -4729G/A (rs3091307) and susceptibility to SMA was determined in children (n = 387) presenting with clinical symptoms of falciparum malaria and resident in a holoendemic transmission region in western Kenya. Our results indicated no difference in the proportions of individual genotypes among children presenting with non-SMA (n = 222) versus SMA (n = 165). Similarly, there was no associations between the individual genotypes (-7402 T/G and -4729G/A) and SMA. Additional analyses, however, revealed that proportions of individuals with -7402 T/-4729A (TA) haplotype was significantly higher in children presenting with SMA than non-SMA group (P = 0.043). A further multivariate logistic regression analyses, controlling for confounding factors, demonstrated that carriage of the TA haplotype was associated with increased susceptibility to SMA (OR; 1.564, 95% CI; 1.023-2.389, P = 0.039). In addition, circulating levels of IL-13 were comparable between the clinical groups as well as across genotypes and haplotypes. Collectively, findings presented here suggest that haplotypes within the IL-13 promoter at -7402 T/G and -4729G/A may modulate SMA pathogenesis, but do not affect circulating IL-13 levels.

Pathogenesis of malaria in tissues and blood

The clinical manifestations of severe malaria are several and occur in different anatomical sites. Both parasite- and host-related factors contribute to the pathogenicity of the severe forms of the disease. Cytoadherence of infected red blood cells to the vascular endothelium of different organs and rosetting are unique features of malaria parasites which are likely to contribute to the vascular damage and the consequent excessive inflammatory/immune response of the host. In addition to cerebral malaria or severe anaemia, which are quite common manifestation of severe malaria, clinical evidences of thrombocytopenia, acute respiratory distress syndrome (ARDS), liver and kidney disease, are reported. In primigravidae from endemic areas, life threatening placental malaria may also be present.

In the following pages, some of the pathogenetic aspects will be briefly reviewed and then data on selected and less frequent manifestation of severe malaria, such as liver or renal failure or ARDS will be discussed.

Deletion of a malaria invasion gene reduces death and anemia, in model hosts

Malaria parasites induce complex cellular and clinical phenotypes, including anemia, cerebral malaria and death in a wide range of mammalian hosts. Host genes and parasite ‘toxins’ have been implicated in malarial disease, but the contribution of parasite genes remains to be fully defined. Here we assess disease in BALB/c mice and Wistar rats infected by the rodent malaria parasite Plasmodium berghei with a gene knock out for merozoite surface protein (MSP) 7. MSP7 is not essential for infection but in P. falciparum, it enhances erythrocyte invasion by 20%. In vivo, as compared to wild type, the P. berghei Δmsp7 mutant is associated with an abrogation of death and a decrease from 3% to 2% in peak, circulating parasitemia. The Δmsp7 mutant is also associated with less anemia and modest increase in the size of follicles in the spleen. Together these data show that deletion of a single parasite invasion ligand modulates blood stage disease, as measured by death and anemia. This work is the first to assess the contribution of a gene present in all plasmodial species in severe disease.

Therapeutical targeting of nucleic acid-sensing Toll-like receptors prevents experimental cerebral malaria

Excessive release of proinflammatory cytokines by innate immune cells is an important component of the pathogenic basis of malaria. Proinflammatory cytokines are a direct output of Toll-like receptor (TLR) activation during microbial infection. Thus, interference with TLR function is likely to render a better clinical outcome by preventing their aberrant activation and the excessive release of inflammatory mediators. Herein, we describe the protective effect and mechanism of action of E6446, a synthetic antagonist of nucleic acid-sensing TLRs, on experimental cerebral malaria (ECM) induced by Plasmodium berghei ANKA. We show that in vitro, low doses of E6446 specifically inhibited the activation of human and mouse TLR9. Tenfold higher concentrations of this compound also inhibited the human TLR8 response to single-stranded RNA. In vivo, therapy with E6446 diminished the activation of TLR9 and prevented the exacerbated cytokine response observed during acute Plasmodium infection. Furthermore, severe signs of ECM, such as limb paralysis, brain vascular leak, and death, were all prevented by oral treatment with E6446. Hence, we provide evidence that supports the involvement of nucleic acid-sensing TLRs in malaria pathogenesis and that interference with the activation of these receptors is a promising strategy to prevent deleterious inflammatory responses that mediate pathogenesis and severity of malaria.

Genome wide linkage study, using a 250K SNP map, of Plasmodium falciparum infection and mild malaria attack in a Senegalese population

Multiple factors are involved in the variability of host's response to P. falciparum infection, like the intensity and seasonality of malaria transmission, the virulence of parasite and host characteristics like age or genetic make-up. Although admitted nowadays, the involvement of host genetic factors remains unclear. Discordant results exist, even concerning the best-known malaria resistance genes that determine the structure or function of red blood cells. Here we report on a genome-wide linkage and association study for P. falciparum infection intensity and mild malaria attack among a Senegalese population of children and young adults from 2 to 18 years old. A high density single nucleotide polymorphisms (SNP) genome scan (Affimetrix GeneChip Human Mapping 250K-nsp) was performed for 626 individuals: i.e. 249 parents and 377 children out of the 504 ones included in the follow-up. The population belongs to a unique ethnic group and was closely followed-up during 3 years. Genome-wide linkage analyses were performed on four clinical and parasitological phenotypes and association analyses using the family based association tests (FBAT) method were carried out in regions previously linked to malaria phenotypes in literature and in the regions for which we identified a linkage peak. Analyses revealed three strongly suggestive evidences for linkage: between mild malaria attack and both the 6p25.1 and the 12q22 regions (empirical p-value = 5×10⁻⁵ and 9×10⁻⁵ respectively), and between the 20p11q11 region and the prevalence of parasite density in asymptomatic children (empirical p-value = 1.5×10⁻⁴). Family based association analysis pointed out one significant association between the intensity of plasmodial infection and a polymorphism located in ARHGAP26 gene in the 5q31–q33 region (p-value = 3.7×10⁻⁵). This study identified three candidate regions, two of them containing genes that could point out new pathways implicated in the response to malaria infection. Furthermore, we detected one gene associated with malaria infection in the 5q31–q33 region.

Chemotherapy-phased imatinib pulses improve long-term outcome of adult patients with Philadelphia chromosome-positive acute lymphoblastic leukemia: Northern Italy Leukemia Group protocol 09/00

PURPOSE

Short imatinib pulses were added to chemotherapy to improve the long-term survival of adult patients with Philadelphia chromosome (Ph) -positive acute lymphoblastic leukemia (ALL), to optimize complete remission (CR) and stem-cell transplantation (SCT) rates.

PATIENTS AND METHODS

Of 94 total patients (age range, 19 to 66 years), 35 represented the control cohort (ie, imatinib-negative [IM-negative] group), and 59 received imatinib 600 mg/d orally for 7 consecutive days (ie, imatinib-positive [IM-positive] group), starting from day 15 of chemotherapy course 1 and from 3 days before chemotherapy during courses 2 to 8. Patients in CR were eligible for allogeneic SCT or, alternatively, for high-dose therapy with autologous SCT followed by long-term maintenance with intermittent imatinib.

RESULTS

CR and SCT rates were greater in the IM-positive group (CR: 92% v 80.5%; P = .08; allogeneic SCT: 63% v 39%; P = .041). At a median observation time of 5 years (range, 0.6 to 9.2 years), 22 patients in the IM-positive group versus five patients in the IM-negative group were alive in first CR (P = .037). Patients in the IM-positive group had significantly greater overall and disease-free survival probabilities (overall: 0.38 v 0.23; P = .009; disease free: 0.39 v 0.25; P = .044) and a lower incidence of relapse (P = .005). SCT-related mortality was 28% (ie, 15 of 54 patients), and postgraft survival probability was 0.46 overall.

CONCLUSION

This imatinib-based protocol improved long-term outcome of adult patients with Ph-positive ALL. With SCT, post-transplantation mortality and relapse remain the major hindrance to additional therapeutic improvement. Additional intensification of imatinib therapy should warrant a better molecular response and clinical outcome, both in patients selected for SCT and in those unable to undergo this procedure.

Animal models of anemia of inflammation

Anemia of inflammation (AI) is a complex multi-organ response to inflammatory disorders. Because AI can result from many infectious and non-infectious inflammatory diseases, multiple mechanisms may contribute to its pathogenesis, including iron restriction, direct erythropoietic suppression, shortened red blood cell survival, and frank hemolysis. Animal models have been helpful in the study of the mechanisms of AI and its potential treatments, but each model reflects distinct aspects of this heterogeneous syndrome. It is therefore important to study a variety of models of AI. This review focuses on the use of infectious and noninfectious mouse models of inflammation that have been shown to manifest anemia. We review many of the models reported in the literature or developed in our laboratory, and discuss their respective merits and drawbacks.

Mapping of Char10, a novel malaria susceptibility locus on mouse chromosome 9

Resistance to blood-stage malaria in AcB55 and AcB61 is caused by a loss of function mutation in pyruvate kinase (Pklr(I90N)). Likewise, pyruvate kinase (PK) deficiency in humans is protective against Plasmodium replication in vitro. We identified a third AcB strain, AcB62 that also carries the Pklr(I90N) mutation. However, AcB62 mice were susceptible to P.chabaudi infection and showed high levels of parasite replication (54-62% peak parasitemia). AcB62 mice showed the hallmarks of PK deficiency-associated anemia similar to AcB55/61 with reticulocytosis, splenic red pulp expansion, tissue iron overload, and increased expression of iron metabolism proteins. This suggests that malaria susceptibility in AcB62 is not because of absence of PK deficiency-associated pathophysiology. To map novel genetic factors affecting malaria susceptibility in AcB62, we generated an informative F2 population using AcB62 (Pklr(I90N)) and CBA-Pk(slc) (Pklr(G338D)) as progenitors and identified a novel locus on chromosome 9 (Char10; LOD=7.24) that controls peak parasitemia. A weaker linkage to the Pklr region of chromosome 3 (LOD=3.7) was also detected, a finding that may reflect the segregation of the two defective Pklr alleles. AcB62 alleles at both loci are associated with higher peak parasitemia. These results identify Char10 as a novel locus modulating severity of malaria in the context of PK deficiency.

Modulation of malaria-induced immunopathology by concurrent gastrointestinal nematode infection in mice

We investigated malaria-associated pathology in mice co-infected with Heligmosomoides polygyrus (Hp) and Plasmodium chabaudi AS (Pc). Despite higher peak parasitemia, co-infected wild-type (WT) C57BL/6 mice displayed similar body weight losses, malarial anaemia, and tissue damage but less severe hypothermia and hypoglycaemia, and earlier reticulocytosis than Pc-infected WT mice. Co-infected STAT6(-/-) mice, deficient in nematode-induced Th2 responses, experienced similar peak parasitemias and generally suffered malaria-associated pathology to a similar degree as co-infected WT mice. These data indicate a complex relationship amongst helminths, malaria and host immune responses resulting in modulation of some but not all aspects of malaria-associated pathology.

Malaria, erythrocytic infection, and anemia

Malaria is a major world health problem. It results from infection of parasites belonging to the genus Plasmodium. Plasmodium falciparum and Plasmodium vivax cause the major human malarias, with P falciparum being the more virulent. During their blood stages of infection, both P falciparum and P vivax induce anemia. Severe malarial anemia caused by P falciparum is responsible for approximately a third of the deaths associated with disease. Malarial anemia appears to be multi-factorial. It involves increased removal of circulating erythrocytes as well as decreased production of erythrocytes in the bone marrow. The molecular mechanisms underlying malarial anemia are largely unknown. Over the last five years, malaria parasite ligands have been investigated for their remodeling of erythrocytes and possible roles in destruction of mature erythrocytes. Polymorphisms in cytokines have been associated with susceptibility to severe malarial anemia: these cytokines and malaria "toxins" likely function by perturbing erythropoiesis. Finally a number of co-infections increase susceptibility to malarial anemia, likely because they exacerbate inflammation caused by malaria. Because of the complexities involved, the study of severe malarial anemia may need a "systems approach" to yield comprehensive understanding of defects in both erythropoiesis and immunity associated with disease. New and emerging tools such as (i) mathematical modeling of the dynamics of host control of malarial infection, (ii) ex vivo perfusion of human spleen to measure both infected and uninfected erythrocyte retention, and (iii) in vitro development of erythroid progenitors to dissect responsiveness to cytokine imbalance or malaria toxins, may be especially useful to develop integrated mechanistic insights and therapies to control this major and fatal disease pathology.