The Imaginal Disc Growth Factors 2 and 3 participate in the Drosophila response to nematode infection

The Drosophila imaginal disc growth factors (IDGFs) induce the proliferation of imaginal disc cells and terminate cell proliferation at the end of larval development. However, the participation of Idgf‐encoding genes in other physiological processes of Drosophila including the immune response to infection is not fully understood. Here, we show the contribution of Idgf2 and Idgf3 in the Drosophila response to infection with Steinernema carpocapsae nematodes carrying or lacking their mutualistic Xenorhabdus nematophila bacteria (symbiotic or axenic nematodes, respectively). We find that Idgf2 and Idgf3 are upregulated in Drosophila larvae infected with symbiotic or axenic Steinernema and inactivation of Idgf2 confers a survival advantage to Drosophila larvae against axenic nematodes. Inactivation of Idgf2 induces the Imd and Jak/Stat pathways, whereas inactivation of Idgf3 induces the Imd, Toll and Jak/Stat pathways. We also show that inactivation of the Imd pathway receptor PGRP‐LE upregulates Idgf2 against Steinernema nematode infection. Finally, we demonstrate that inactivation of Idgf3 induces the recruitment of larval haemocytes in response to Steinernema. Our results indicate that Idgf2 and Idgf3 might be involved in different yet crucial immune functions in the Drosophila antinematode immune response. Similar findings will promote the development of new targets for species‐specific pest control strategies.     

Flt3 ligand treatment modulates parasitemia during infection with rodent malaria parasites via MyD88‐ and IFN‐γ‐dependent mechanisms

We previously showed that treatment of mice with the Flt3 ligand (Flt3L) prevents development of lethal experimental cerebral malaria and inhibits parasitemia during Plasmodium berghei ANKA (PbA) infection. In this study, we investigated the mechanisms underlying the reduction of parasitemia in Flt3L‐treated mice. Studies using gene knockout mice and antibody treatment indicated that the anti‐parasitemia effect of Flt3L was mediated by innate immune system and was dependent on MyD88, IFN‐γ, IL‐12 and natural killer (NK) cells. The number of NK cells and their ability to produce IFN‐γ was enhanced in Flt3L‐treated mice. Phagocytic activity of splenocytes was increased in Flt3L‐treated mice after PbA infection when compared with that in untreated mice, and this activity was mainly mediated by the accumulation of F4/80^midCD11b⁺ cells in the spleen. In both MyD88^?/? and IFN‐γ^?/? mice, the proportion of F4/80^midCD11b⁺ cells was not increased in the spleen of Flt3L‐treated mice after infection. These correlations suggest that NK cells produce IFN‐γ in Flt3L‐treated mice, and accumulation of F4/80^midCD11b⁺ cells in the spleen is promoted by an IFN‐γ ‐dependent manner, culminating in the inhibition of parasitemia. These findings imply that Flt3L promotes effective innate immunity against malaria infection mediated by interplay among varieties of innate immune cells.     

Splenocyte apoptosis in Plasmodium berghei ANKA infection: possible role of TNF‐α and TGF‐β

Cerebral malaria is associated with the circulating levels of tumour necrosis factor alpha (TNF‐α) and transforming growth factor β (TGF‐β), but association between these two cytokines and implications in splenocyte apoptosis remain largely obscured. We have evaluated the outcome of TGF‐β and TNF‐α production in the context of splenocyte apoptosis during Plasmodium berghei ANKA (PbA) infection. Blood‐stage PbA infection confirmed blood–brain barrier disruption, disarray of white pulp, increase in percentage of sub‐G0/G1 and splenocyte apoptosis. Flow cytometric analysis reveals up‐regulation of Fas‐L followed by caspase‐8 and caspase‐3 activation and signifies possible involvement of Fas‐L‐mediated splenocyte apoptosis. We have observed down‐regulation of TGF‐β and up‐regulation of TNF‐α in tissue and serum level, respectively, during PbA infection. Association between the production of TGF‐β and the severity of malaria infection in splenocytes was verified with TGF‐β inhibitor that exacerbated the apoptotic process. In contrary, TNF‐α inhibitor causes significant delay in apoptotic process, but could not alter the lethality of parasite. Thus, results from this study suggest that the critical balance between TGF‐β and TNF‐α might have a key role on Fas‐L‐mediated splenocyte apoptosis during experimental cerebral malaria.     

Different switching patterns of β‐thalassaemic mutations at the proximal and distal CACCC box of the human HBB (β‐globin) gene

Stored platelets undergo biochemical, structural and functional changes that lead to decreased efficacy and safety of platelet transfusions. Not only do platelets acquire markers of activation during storage, but they also fail to respond normally to agonists post‐storage. We hypothesized that resveratrol, a cardioprotective antioxidant, could act as a novel platelet storage additive to safely prevent unwanted platelet activation during storage, while simultaneously preserving normal haemostatic function. Human platelets treated with resveratrol and stored for 5 d released less thromboxane B₂ and prostaglandin E₂ compared to control platelets. Resveratrol preserved the ability of platelets to aggregate, spread and respond to thrombin, suggesting an improved ability to activate post‐storage. Utilizing an in vitro model of transfusion and thromboelastography, clot strength was improved with resveratrol treatment compared to conventionally stored platelets. The mechanism of resveratrol's beneficial actions on stored platelets was partly mediated through decreased platelet apoptosis in storage, resulting in a longer half‐life following transfusion. Lastly, an in vivo mouse model of transfusion demonstrated that stored platelets are prothrombotic and that resveratrol delayed vessel occlusion time to a level similar to transfusion with fresh platelets. We show resveratrol has a dual ability to reduce unwanted platelet activation during storage, while preserving critical haemostatic function.     

Association of mannose‐binding lectin gene polymorphisms with Kawasaki disease in the Japanese

Objective: Kawasaki disease (KD) is a systemic vasculitis in childhood; its etiology is unknown. The possibility that KD is an infectious disease has been discussed and investigated for decades, in light of the implication that infections are involved in the pathogenesis of KD. Young children rely on their innate immune system for protection against virus and micro‐organisms. Human mannose binding lectin (MBL) is a C‐type serum lectin synthesized by the liver as an acute phase protein and it plays an important role in the innate immune system. Here, we investigate the relationship between the MBL gene polymorphisms and the occurrence of KD in the Japanese population. Method: The frequencies of the genotypes, defined as mutations in codons 52, 54 and 57, and the functional promoter variants of the MBL were determined in 45 patients with KD. Results: The MBL codon‐54 polymorphism frequency of heterozygote (GGC/GAC) and promoter variants were significantly higher in the KD group than that in the control group (P < 0.05). Neither group showed codon 52 nor 57 polymorphisms. Conclusion: It is possible that mutations of the MBL gene might be related to the trigger of the pathogenesis of Kawasaki disease.     

α‐thalassaemia masked by β gene defects and a new polyadenylation site mutation on the α2‐globin gene

We report three examples of chronic anaemia involving complex combinations of α‐ and β‐globin gene defects. The first case had a potential Hb H disease caused by the classic SEA/RW deletions masked by Hb E [β26(B8)Glu→Lys] in the homozygous state. The second had an unusual Hb H disease caused by compound heterozygosity for two different α2 polyadenylation site mutations masked by a β‐thalassaemia heterozygosity. The third had an intermediate α‐thalassaemia with considerable anaemia caused by an as yet unknown polyadenylation site (AATAAA>AATAAC) mutation in combination with a common RW deletion masked by a common Hb C [β6(A3)Glu→Lys] heterozygosity. Diagnostic methods, genotype/phenotype correlations and the chance of overlooking these combinations during risk assessment in a multiethnic society are discussed.     

IL‐28B (IFN‐λ3) and IFN‐α synergistically inhibit HCV replication

Genetic variation in the IL‐28B (interleukin‐28B; interferon lambda 3) region has been associated with sustained virological response (SVR) rates in patients with chronic hepatitis C treated with peginterferon‐α and ribavirin. However, the mechanisms by which polymorphisms in the IL‐28B gene region affect host antiviral responses are not well understood. Using the HCV 1b and 2a replicon system, we compared the effects of IFN‐λs and IFN‐α on HCV RNA replication. The anti‐HCV effect of IFN‐λ3 and IFN‐α in combination was also assessed. Changes in gene expression induced by IFN‐λ3 and IFN‐α were compared using cDNA microarray analysis. IFN‐λs at concentrations of 1 ng/mL or more exhibited concentration‐ and time‐dependent HCV inhibition. In combination, IFN‐λ3 and IFN‐α had a synergistic anti‐HCV effect; however , no synergistic enhancement was observed for interferon‐stimulated response element (ISRE) activity or upregulation of interferon ‐ stimulated genes (ISGs). With respect to the time course of ISG upregulation, the peak of IFN‐λ3‐induced gene expression occurred later and lasted longer than that induced by IFN‐α. In addition, although the genes upregulated by IFN‐α and IFN‐λ3 were similar to microarray analysis, interferon‐stimulated gene expression appeared early and was prolonged by combined administration of these two IFNs. In conclusion, IFN‐α and IFN‐λ3 in combination showed synergistic anti‐HCV activity in vitro. Differences in time‐dependent upregulation of these genes might contribute to the synergistic antiviral activity.     

NK cells in HIV‐1 infection: evidence for their role in the control of HIV‐1 infection

Increasing evidence supports the notion that the innate immune response, and in particular, natural killer cells play a central role in determining the quality of the host immune response to infection. In this review we highlight recent evidence that suggests that NK cells influence the clinical fate of HIV‐infected individuals.     

Association between β‐adrenoceptor gene polymorphisms and relative response to β2‐agonists and anticholinergic drugs in Japanese asthmatic patients

Background and objective: Whether β₂‐adrenoceptor gene (ADRB2) polymorphisms are associated with airway responsiveness to β₂‐agonist medications remains controversial, partly due to factors that may confound pharmacogenetic associations, including age, cigarette smoking and airway remodelling. To overcome these problems, we performed an analysis using parameters that reflected the specific bronchodilator response to β₂‐agonists. Methods: The increases in FEV₁ after inhalation of procaterol hydrochloride (ΔFEV₁ procaterol) or oxitropium bromide (ΔFEV₁ oxitropium), and after sequential inhalation of procaterol and oxitropium (total airway reversibility), were measured in 81 Japanese patients with moderate to severe asthma. Approximately 3 kb of the DNA sequence of the coding and 5′‐flanking regions of ADRB2 were genotyped by direct sequencing and PCR‐restriction fragment length polymorphism assay. Results: The mean age of the participants was 54 years, and 38 (47%) were smokers. Although ΔFEV₁ procaterol and ΔFEV₁ oxitropium adjusted for predicted FEV₁ were not associated with ADRB2 polymorphisms, the ratio of ΔFEV₁ procaterol to total airway reversibility was significantly associated with the ADRB2 A46G genotype (P < 0.05). Patients who were homozygous for the A46 allele (arginine at amino acid 16) were more responsive than carriers of the G46 (glycine 16) allele (P = 0.008). Multivariate linear regression analysis showed that ΔFEV₁ procaterol was correlated with the number of A46 alleles (P = 0.014), and also with total airway reversibility (P < 0.001) and smoking index in current smokers (P = 0.009). Conclusions: The ADRB2 A46G polymorphism was associated with a relatively greater bronchodilator responsiveness to β₂‐agonists even in elderly asthmatic patients and smokers.     

Interaction of heterozygous βo-thalassemia with single functional α-globin gene

In this study, we analyzed the phenotypic manifestations resulting from the interaction of heterozygous β^o-thalassemia(β^o-39 nonsense mutation) with the functional loss of three α-globin structural genes in six subjects, of whom four had the [-αl–] α-globin genotype and two the [–/αThα] α-globin genotype. The β-thalassemia defect was in all cases the nonsense mutation at codon 39. The nondeletion α-thalassemia α^th was the initiation codon mutation (AUG→GUG) of the α-2 gene. In all these subjects hypochromia and microcytosis were more marked than in βα -thalassemia heterozygotes with a full complement of four α-globin genes. All but one had moderate anemia. The α:β globin chain synthesis ratios were consistently decreased. No cases had Hb H on electrophoresis. Subjects with [–/αThα] α-globin genotype had more severe thalassemia-like manifestations than those with [–/-α] α-globin genotype.     

Resiniferatoxin lowers TNF‐α, NO and PGE2 in the intestinal phase and the parasite burden in the muscular phase of Trichinella spiralis infection

During the course of infection with Trichinella spiralis, an inflammatory response is triggered at the intestinal level in the host, playing a crucial role in the expulsion and elimination of the parasite. However, several studies have demonstrated that this inflammatory response is harmful to the host; hence, the importance of studying molecules with therapeutic potential like resiniferatoxin, which is known to have an anti‐inflammatory effect both in vitro and in vivo. In this article, we evaluated the anti‐inflammatory activity of resiniferatoxin during the intestinal phase of T. spiralis infection by quantitatively determining the levels of TNF‐α, NO and PGE₂ as well as the percentage of eosinophils in the blood and intestinal pathology. In addition, parasite burden was determined during the muscle infection. Our results show that resiniferatoxin lowered the serum levels of TNF‐α, NO and PGE₂, as well as the percentage of eosinophils in the blood and intestinal pathology during the intestinal infection. Moreover, resiniferatoxin also lowered the parasite burden in muscle, resulting in a reduction of the humoral response (IgG) associated to treatment with resiniferatoxin. These findings suggest a potential therapeutic use of the anti‐inflammatory effect of resiniferatoxin, which also contributes to host defence against the challenge of T. spiralis infection.