Immune response of γδT cells in Schistosome japonicum–infected C57BL/6 mouse liver

Systematic evaluation of the role of γδT cells during the Schistosoma japonicum infection has not been reported, despite the fact that γδT cells contribute to many infectious diseases in innate immunity. Therefore, the aim of this study was to observe the properties of γδT cells in the liver of C57BL/6 mice infected by S. japonicum. In this report, using immuno‐fluorescent histological analysis, γδT cells were found around hepatic granulomatous. Moreover, the flow cytometry results revealed that the percentage of hepatic γδT cells increased significantly after S. japonicum infection. More interestingly, a subset of CD3^?γδTCR⁺ cells were found and markedly increased after infection. Furthermore, expression of activation markers (CD25 and CD69) and cytokine profiles were detected in these hepatic CD3⁺γδTCR⁺and CD3^?γδTCR⁺ cells. The significantly higher level of CD69, IL‐4 and IL‐17 were observed in CD3⁺γδTCR⁺ cells after infection, suggesting that CD3⁺γδTCR⁺ cells instead of CD3^?γδTCR⁺ cells might play a predominant role during the infection. Finally, our results indicated that the expression of NKG2D on CD3⁺γδTCR⁺ cells was higher than that on CD3^?γδTCR⁺ cells. Collectively, γδT cells could play an important role in the liver of C57BL/6 mouse during japonicum infection.     

Batf3 deficiency proves the pivotal role of CD8α+ dendritic cells in protection induced by vaccination with attenuated Plasmodium sporozoites

Increasing evidence indicates that hepatic CD8α⁺ dendritic cells (DCs) are important antigen cross‐presenting cells (APC) involved in the priming of protective CD8⁺ T‐cell responses induced by live‐attenuated Plasmodium sporozoites. Experimental proof for a critical role of CD8α⁺ DCs in protective pre‐erythrocytic malaria immunizations has pivotal implications for vaccine development, including improved vectored subunit vaccines. Employing Batf3^?/? mice, which lack functional CD8α⁺ DCs, we demonstrate that deficiency of these particular APCs completely abolishes protection and corresponding signatures of vaccine‐induced immunity. We show that in wild‐type, but not in Batf3^?/?, mice CD8α⁺ DCs accumulate in the liver after immunization with live irradiation‐attenuated P. berghei sporozoites. IFN‐γ production by Plasmodium antigen‐specific CD8⁺ T cells is dependent on functional Batf3. In addition, our results demonstrate that the dysfunctional cDC‐CD8+ T‐cell axis correlates with MHC class II upregulation on splenic CD8α^? DCs. Collectively, these findings underscore the essential role of CD8α⁺ DCs in robust protection induced by experimental live‐attenuated malaria vaccines.     

Impact of γ‐chain cytokines on T cell homeostasis in HIV‐1 infection: therapeutic implications

Abstract. Gougeon M‐L, Chiodi F (Institut Pasteur, Paris, France, and Karolinska Institutet, Stockholm, Sweden) Impact of γ‐chain cytokines on T cell homeostasis in HIV‐1 infection: therapeutic implications (Symposium). J Intern Med 2010; 267 : 502–514. CD4⁺ T cell lymphocytes are a major target for human immunodeficiency virus type‐1 (HIV‐1) infection. During this chronic infection, CD4⁺ T cell loss (induced through direct viral replication), generalized immune activation and increased susceptibility to apoptosis result in impaired T cell homeostasis with subsequent development of opportunistic infections and cancers. Highly active antiretroviral therapy (HAART) has a well‐defined, beneficial effect on HIV‐1‐related clinical outcome; however, it does not lead to normalization of immune dysregulation. In order to boost both CD4⁺ T cell restoration and HIV‐1 specific immunity, immunotherapy with γ‐chain cytokines has been used in HIV‐1‐infected patients during concomitant HAART. In this review, we summarize the role of γ‐chain cytokines, especially interleukin (IL)‐2 and IL‐7, in influencing T cell homeostasis and proliferation, and discuss how immunotherapy with these cytokines may be beneficial to reconstitute the T cell compartment in the context of HIV‐1 infection. The intriguing results of two large trials evaluating the efficacy of IL‐2 in restoring immune function during HIV‐1 infection are also discussed. In addition, we consider the promises and caveats of the first phase I/II clinical trials with IL‐7 in HIV‐1‐infected patients and the knowledge that is still lacking in the field of T cell reconstitution through γ‐chain cytokines.     

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.     

Expansion of circulating CD56bright natural killer cells in patients with JAK2‐positive chronic myeloproliferative neoplasms during treatment with interferon‐α

In recent years, major molecular remissions have been observed in patients with JAK2‐positive chronic myeloproliferative neoplasms (MPNs) after therapy with IFN‐α. IFN‐α is known to have altering effects on immune cells involved in immune surveillance and might consequently enhance anti‐tumor immune response against the JAK2‐mutated clone. The objective of this study was to investigate circulating levels and phenotype of natural killer cells in 29 JAK2‐positive MPN patients during IFN‐α treatment. Furthermore, functional studies of NK cells upon target‐cell recognition and cytokine stimulation were performed. The CD56^bright and CD56^dim NK cell subtypes display different properties in terms of cytokine production and cytotoxicity, respectively. Our results show a significant increase in the proportion of CD56^bright NK cells and a decreasing CD56^dim population during treatment with IFN‐α compared to patients that are untreated, treated with hydroxyurea and healthy controls, P < 0.0001. Furthermore, an overall increase in cytokine‐dependent (IL‐12 and IL‐15) IFN‐γ expression by CD56^dim NK cells during IFN‐α treatment was observed. In contrast, our data indicate a compromised NK cell response to target‐cell recognition during treatment with IFN‐α in four patients. We also report low levels of circulating NK cells in untreated patients compared to healthy donors, patients treated with hydroxyurea and IFN‐α, P = 0.02. Based on our findings, one might speculate whether treatment with IFN‐α skews the human NK population toward a helper type that may assist in CD8⁺ T cell priming in lymphoid tissues at the expense of their immediate cytotoxic functions in peripheral blood and tissues.     

IFN-γ and TNF-α secretion by CD4+ and CD8+ TCRαβ+ T-cell clones derived early after allogeneic bone marrow transplantation

Abstract: Secretion of the potentially antileukaemic cytokines IFN-γ and TNF-α was investigated for CD4 ⁺ and CD8 ⁺ TCRαβ⁺ T-cell clones derived from 4 leukaemia patients 3–6 weeks after allogeneic BMT. We investigated cytokine secretion in response to the activation signal accessory cells + phytohaemagglutinin + Interleukin 2. All clones derived after BMT were capable of IFN-γ and TNF-α secretion, and both for CD4⁺ (n = 96) and CD8⁺ (n = 8) T cells quantities of IFN-γ and TNF-α were significantly correlated with one another. When comparing the overall results for posttransplant and normal T-cell clones derived from 2 bone marrow donors (n = 65), both CD4⁺ and CD8⁺ TCRαβ⁺ T-cell clones showed increased IFN-γ production, and CD4⁺ but not CD8⁺ clones showed a decreased TNF-α secretion. The results suggest that noncytotoxic T cells derived after allogeneic BMT can produce IFN-γ and TNF-α and may thus be capable of mediating antileukaemic effects.     

α‐Galactosylceramide activates antitumor immunity against liver tumor

Aim: α‐Galactosylceramide (α‐GalCer) has been attracting attention as a novel approach to treat metastatic liver cancer. We investigated the detailed process of activating liver dendritic cells (DC) and immune cells after α‐GalCer treatment in the mouse liver tumor model. Methods: BALB/c mice bearing CMS4 liver tumor (p53 peptide‐expressing tumor) were treated by α‐GalCer. We evaluated the activation of liver DC and immune cells after α‐GalCer treatment. Interferon (IFN)‐γ enzyme‐linked immunosorbent spot (ELISPOT) assay was performed to detect p53 peptide‐specific cytotoxic T lymphocytes (CTL). To assess the impact of systemic acquired immunity by α‐GalCer treatment, 28 days after liver tumor treatment, CMS4 cells or Colon26 cells were re‐challenged s.c. Results: The liver weights of α‐GalCer‐treated mice were significantly lighter than those of vehicle‐treated mice. Depletion experiments revealed that natural killer (NK) cells were essential for the antitumor effect of α‐GalCer. α‐GalCer treatment significantly increased the population of DC and NK cells in the liver. The expressions of co‐stimulatory molecules on liver DC significantly increased with the peak at 1 day after α‐GalCer administration. IFN‐γ ELISPOT assay demonstrated that p53 peptide‐specific CTL was generated efficiently in α‐GalCer‐treated mice. ⁵¹Cr‐release assay revealed that CD8⁺, not CD4⁺, CTL against CMS4 cells were generated in α‐GalCer‐treated mice. The mice that had been protected from CMS4 liver tumor by α‐GalCer injection became resistant against s.c. CMS4 re‐challenge, but not against Colon26 re‐challenge. Conclusion: These results demonstrated the therapeutic potential of α‐GalCer against liver cancer through activating liver DC and immune cells in the liver.     

Recognition of the antigen-presenting molecule MR1 by a Vδ3+ γδ T cell receptor

Unlike conventional αβ T cells, γδ T cells typically recognize nonpeptide ligands independently of major histocompatibility complex (MHC) restriction. Accordingly, the γδ T cell receptor (TCR) can potentially recognize a wide array of ligands; however, few ligands have been described to date. While there is a growing appreciation of the molecular bases underpinning variable (V)δ1⁺ and Vδ2⁺ γδ TCR-mediated ligand recognition, the mode of Vδ3⁺ TCR ligand engagement is unknown. MHC class I–related protein, MR1, presents vitamin B metabolites to αβ T cells known as mucosal-associated invariant T cells, diverse MR1-restricted T cells, and a subset of human γδ T cells. Here, we identify Vδ1/2⁻ γδ T cells in the blood and duodenal biopsy specimens of children that showed metabolite-independent binding of MR1 tetramers. Characterization of one Vδ3Vγ8 TCR clone showed MR1 reactivity was independent of the presented antigen. Determination of two Vδ3Vγ8 TCR-MR1-antigen complex structures revealed a recognition mechanism by the Vδ3 TCR chain that mediated specific contacts to the side of the MR1 antigen-binding groove, representing a previously uncharacterized MR1 docking topology. The binding of the Vδ3⁺ TCR to MR1 did not involve contacts with the presented antigen, providing a basis for understanding its inherent MR1 autoreactivity. We provide molecular insight into antigen-independent recognition of MR1 by a Vδ3⁺ γδ TCR that strengthens an emerging paradigm of antibody-like ligand engagement by γδ TCRs.

Characterized by both innate and adaptive immune cell functions, γδ T cells are an unconventional T cell subset. While the functional role of γδ T cells is yet to be fully established, they can play a central role in antimicrobial immunity (1), antitumor immunity (2), tissue homeostasis, and mucosal immunity (3). Owing to a lack of clarity on activating ligands and phenotypic markers, γδ T cells are often delineated into subsets based on the expression of T cell receptor (TCR) variable (V) δ gene usage, grouped as Vδ2⁺ or Vδ2⁻.The most abundant peripheral blood γδ T cell subset is an innate-like Vδ2⁺subset that comprises ∼1 to 10% of circulating T cells (4). These cells generally express a Vγ9 chain with a focused repertoire in fetal peripheral blood (5) that diversifies through neonatal and adult life following microbial challenge (6, 7). Indeed, these Vγ9/Vδ2⁺ T cells play a central role in antimicrobial immune response to Mycobacterium tuberculosis (8) and Plasmodium falciparum (9). Vγ9/Vδ2⁺ T cells are reactive to prenyl pyrophosphates that include isopentenyl pyrophosphate and (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (8) in a butyrophilin 3A1- and BTN2A1-dependent manner (10–13). Alongside the innate-like protection of Vγ9/Vδ2⁺ cells, a Vγ9⁻ population provides adaptive-like immunobiology with clonal expansions that exhibit effector function (14).The Vδ2⁻ population encompasses the remaining γδ T cells but most notably the Vδ1⁺ and Vδ3⁺ populations. Vδ1⁺ γδ T cells are an abundant neonatal lineage that persists as the predominating subset in adult peripheral tissue including the gut and skin (15–18). Vδ1⁺ γδ T cells display potent cytokine production and respond to virally infected and cancerous cells (19). Vδ1⁺ T cells were recently shown to compose a private repertoire that diversifies, from being unfocused to a selected clonal TCR pool upon antigen exposure (20–23). Here, the identification of both Vδ1⁺ T_naive and Vδ1⁺ T_effector subsets and the Vδ1⁺ T_naive to T_effector differentiation following in vivo infection point toward an adaptive phenotype (22).The role of Vδ3⁺ γδ T cells has remained unclear, with a poor understanding of their lineage and functional role. Early insights into Vδ3⁺ γδ T cell immunobiology found infiltration of Vδ3⁺ intraepithelial lymphocytes (IEL) within the gut mucosa of celiac patients (24). More recently it was shown that although Vδ3⁺ γδ T cells represent a prominent γδ T cell component of the gut epithelia and lamina propria in control donors, notwithstanding pediatric epithelium, the expanding population of T cells in celiac disease were Vδ1⁺ (25). Although Vδ3⁺ IELs compose a notable population of gut epithelia and lamina propria T cells (∼3 to 7%), they also formed a discrete population (∼0.2%) of CD4⁻CD8⁻ T cells in peripheral blood (26). These Vδ3⁺ DN γδ T cells are postulated to be innate-like due to the expression of NKG2D, CD56, and CD161 (26). When expanded in vitro, these cells degranulated and killed cells expressing CD1d and displayed a T helper (Th) 1, Th2, and Th17 response in addition to promoting dendritic cell maturation (26). Peripheral Vδ3⁺ γδ T cells frequencies are known to increase in systemic lupus erythematosus patients (27, 28), and upon cytomegalovirus (29) and HIV infection (30), although, our knowledge of their exact role and ligands they recognize remains incomplete.The governing paradigms of antigen reactivity, activation principles, and functional roles of γδ T cells remain unresolved. This is owing partly due to a lack of knowledge of bona fide γδ T cell ligands. Presently, Vδ1⁺ γδ T cells remain the best characterized subset with antigens including Major Histocompatibility Complex (MHC)-I (31), monomorphic MHC-I–like molecules such as CD1b (32), CD1c (33), CD1d (34), and MR1 (35), as well as more diverse antigens such as endothelial protein coupled receptor (EPCR) and phycoerythrin (PE) (36, 37). The molecular determinants of this reactivity were first established for Vδ1⁺ TCRs in complex with CD1d presenting sulfatide (38) and α-galactosylceramide (α-GalCer) (34), which showed an antigen-dependent central focus on the presented lipids and docked over the antigen-binding cleft.In humans, mucosal-associated invariant T (MAIT) cells are an abundant innate-like αβ T cell subset typically characterized by a restricted TCR repertoire (39–43) and reactivity to the monomorphic molecule MR1 presenting vitamin B precursors and drug-like molecules of bacterial origin (41, 44–46). Recently, populations of atypical MR1-restricted T cells have been identified in mice and humans that utilize a more diverse TCR repertoire for MR1-recognition (42, 47, 48). Furthermore, MR1-restricted γδ T cells were identified in blood and tissues including Vδ1⁺, Vδ3⁺, and Vδ5⁺ clones (35). As seen with TRAV 1-2⁻, unconventional MAITs cells the isolated γδ T cells exhibited MR1-autoreactivity with some capacity for antigen discrimination within the responding compartment (35, 48). Structural insight into one such MR1-reactive Vδ1⁺ γδ TCR showed a down-under TCR engagement of MR1 in a manner that is thought to represent a subpopulation of MR1-reactive Vδ1⁺ T cells (35). However, biochemical evidence suggested other MR1-reactive γδ T cell clones would likely employ further unusual docking topologies for MR1 recognition (35).Here, we expanded our understanding of a discrete population of human Vδ3⁺ γδ T cells that display reactivity to MR1. We provide a molecular basis for this Vδ3⁺ γδ T cell reactivity and reveal a side-on docking for MR1 that is distinct from the previously determined Vδ1⁺ γδ TCR-MR1-Ag complex. A Vδ3⁺ γδ TCR does not form contacts with the bound MR1 antigen, and we highlight the importance of non–germ-line Vδ3 residues in driving this MR1 restriction. Accordingly, we have provided key insights into the ability of human γδ TCRs to recognize MR1 in an antigen-independent manner by contrasting mechanisms.     

The effect of Echinococcus granulosus on spleen cells and TGF‐β expression in the peripheral blood of BALB/c mice

Cystic echinococcosis (CE) caused by the cestode Echinococcus granulosus (E. granulosus) is a zoonotic parasitic disease. The effective immune evasion mechanisms of E. granulosus allow it to parasitize its hosts. However, the status of the innate and adaptive immune cells and their contributions to E. granulosus progression remain poorly understood. In this study, we aimed to determine the impact of E. granulosus infection on T cells, NK cell responses and TGF‐β expression during the early infection phase in BALB/c mice. In E. granulosus infections, there was an increasing tendency in the percentage of CD4⁺CD25⁺ T cells and CD4⁺Foxp3⁺ T cells and peripheral blood TGF‐β levels and relative expression of the Foxp3 gene. Moreover, there were a decreasing tendency in the percentage of NK cells and NK cell cytotoxicity and the expression of NKG2D on NK cells. The TGF‐β1/Smad pathway was activated by E. granulosus in mice. Above results can be reversed by the inhibitor SB‐525334 (potent activin receptor‐like kinase 5 inhibitor). These results suggest that the TGF‐β/Smad pathway plays an important role in changes of T‐cell or NK cell responses. These results may contribute to revealing the preliminary molecular mechanisms in establishing hydatid infection.     

Polarization of granulocytic myeloid‐derived suppressor cells by hepatitis C core protein is mediated via IL‐10/STAT3 signalling

Myeloid‐derived suppressor cells (MDSCs) have been described as suppressors of T‐cell function in many malignancies. Impaired T‐cell responses have been observed in patients with chronic hepatitis C virus infection (CHC), which is reportedly associated with the establishment of persistent HCV infection. Therefore, we hypothesized that MDSCs also play a role in chronic HCV infection. MDSCs in the peripheral blood of 206 patients with CHC and 20 healthy donors were analyzed by flow cytometry. Peripheral blood mononuclear cells (PBMCs) of healthy donors cultured with hepatitis C virus core protein (HCVc) were stimulated with or without interleukin 10 (IL‐10). Compared to healthy donors and certain CHC patients with sustained viral response (SVR), CHC patients without SVR presented with a dramatic elevation of G‐MDSCs with the HLA‐DR^?/lowCD33⁺CD14^?CD11b⁺ phenotype in peripheral blood. The frequency of G‐MDSCs in CHC patients was positively correlated with serum HCVc, and G‐MDSCs were induced from healthy PBMCs by adding exogenous HCVc. Furthermore, we revealed a potential mechanism by which HCVc mediates G‐MDSC polarization; activation of ERK1/2 resulting in IL‐10 production and IL‐10‐activated STAT3 signalling. Finally, we confirmed that HCVc‐induced G‐MDSCs suppress the proliferation and production of IFN‐γ in autologous T‐cells. We also found that the frequency of G‐MDSCs in serum was associated with CHC prognosis. HCVc maintains immunosuppression by promoting IL‐10/STAT3‐dependent differentiation of G‐MDSCs from PBMCs, resulting in the impaired functioning of T‐cells. G‐MDSCs may thus be a promising biomarker for predicting prognosis of CHC patients.     

IL28B genetic variation and hepatitis C virus–specific CD4+ T‐cell responses in anti‐HCV‐positive blood donors

Summary. Epidemiological, viral and host factors are associated with the outcome of hepatitis C virus (HCV) infection, and strong host immune responses against HCV favour viral clearance. Recently, genome‐wide association studies have shown a strong correlation between single‐nucleotide polymorphisms (SNPs) near the interleukin‐28B (IL28B) gene and spontaneous or treatment‐induced HCV clearance. We have investigated whether protective IL28B genetic variants are associated with HCV‐specific T‐cell responses among Spanish blood donors. The rs12979860 IL28B haplotype was determined in 69 anti‐HCV‐positive blood donors (21 HCV RNA negative and 48 HCV RNA positive) and 30 seronegative donors. In all cases, HCV‐specific CD4⁺ T‐cell responses to HCV recombinant proteins (core, NS3 and NS3 helicase) were assessed by ex vivo interferon‐γ ELISpot assay. The rs12979860‐CC genotype was highly overrepresented in donors with spontaneous HCV clearance when compared to those with chronic infection (76.2%vs 29.2%, P < 0.001; odds ratio, 7.77; 95% confidence interval, 2.4–25.3, P < 0.001). HCV‐specific CD4⁺ T‐cell responses were detected in 16 (76.2%) spontaneous resolvers especially towards nonstructural proteins, but with no correlation with IL28B genotype. Chronic individuals had a significantly lower overall T‐cell response again irrespective of IL28B genotype. When spontaneous resolvers and chronic individuals were stratified according to their IL28B genotype, significantly stronger T‐cell responses were only observed among those with non‐CC haplotypes. Although the protective rs12979860 IL28B CC genotype is associated with spontaneous HCV clearance, stronger CD4⁺ T‐cell responses towards NS3 were only evident among those with non‐CC haplotypes.     

Immunophenotypic analysis of T‐acute lymphoblastic leukemia. A CD5‐based ETP‐ALL perspective of non‐ETP T‐ALL

T‐cell antigens [CD5,CD1a,CD8] define early T‐cell precursor acute lymphoblastic leukemia (ETP‐ALL). To understand immature T‐ALL of which ETP‐ALL is part, we used these antigens to subcategorize non‐ETP T‐ALL for examining expression of myeloid/stem cell antigens (M/S) and clinical features. Using CD5 (+/?) to start categorization, we studied 69 routinely immunophenotyped patients with T‐ALL. CD5^? was a homogenous (CD8,CD1a)^? M/S⁺ ETP‐ALL group (n = 9). CD5⁺ cases were (CD8,CD1a)^? pre‐T‐ALL (n = 22) or (CD8,CD1a)⁺ (n = 38) thymic/cortical T‐ALL; M/S⁺ 20/22 (90.91%) in former and 22/38 (57.89%) in latter (P = 0.007). ETP‐ and pre‐T‐ALL together (CD1a^?,CD5^?/+ immature T‐ALL group) were nearly always M/S⁺ (29/31; 93.55%). In multivariate analysis, only ETP‐ALL predicted poor overall survival (P = 0.02). We conclude (i) CD5 negativity in T‐ALL almost always means ETP‐ALL. CD1a and CD8 negativity, as much as CD5, marks immaturity in T‐ALL, and the CD5^+/?/CD1a^?/CD8^? immature T‐ALL group needs further study to understand the biology of the T‐ALL–myeloid interface. (ii) ETP‐ALL patients may be pre‐T‐ALL if CD2⁺; CD2⁺, conversely, CD5^?/CD1a^?/CD8^? pre‐T ALL patients are ETP‐ALL. (iii) Immunophenotypic workup of T‐ALL must not omit CD1a, CD5, CD8 and CD2, and positivity of antigens should preferably be defined as recommended for ETP‐ALL, so that this entity can be better evaluated in future studies of immature T‐ALL, a group to which ETP‐ALL belongs. (iv) ETP‐ALL has poor prognosis.     

Significance of periductal Langerhans cells and biliary epithelial cell‐derived macrophage inflammatory protein‐3α in the pathogenesis of primary biliary cirrhosis

Background/aims: To clarify the primary biliary cirrhosis (PBC)‐specific antigen‐presenting mechanism, we examined the distribution and phenotypic characteristics of infiltrating dendritic cells (DCs) with respect to bile ducts and the mechanism of migration in terms of the periductal cytokine milieu and biliary innate immunity. Methods and results: Immunohistochemistry using liver sections from patients with PBC and controls revealed that blood dendritic cell antigen (BDCA)‐2⁺ plasmacytoid DCs were found mainly in the portal tracts in PBC and the controls, but their distribution was not related to bile ducts. BDCA‐1⁺ and CD19^? myeloid DCs were also found in portal tracts in PBC and the controls and, in particular, Langerin+Langerhans cells (LCs) were dominantly scattered around or within biliary epithelial layers of the damaged bile ducts in PBC. Moreover, experiments with cultured human biliary epithelial cells (BECs) showed that an LC‐attracting chemokine, macrophage inflammatory protein‐3α, was produced by BECs in the response to cytokines [interleukin (IL)‐1β, tumour necrosis factor‐α and IL‐17] and pathogen‐associated molecular patterns. Conclusions: LCs existing around or within biliary epithelial layers are important as periductal antigen‐presenting cells in PBC and the migration of LCs into bile ducts is closely associated with the periductal cytokine milieu and biliary innate immunity in PBC.     

Persistent gamma delta T‐cell dysfunction in chronic HCV infection despite direct‐acting antiviral therapy induced cure

Immune dysfunction is a hallmark of chronic HCV infection and viral clearance with direct antivirals recover some of these immune defects. TCRVγ9Vδ2 T‐cell dysfunction in treated HCV patients however is not well studied and was the subject of this investigation. Peripheral blood cells from patients who had achieved sustained virologic response (SVR) or those who had relapsed after interferon‐free therapy were phenotyped using flow cytometry. Functional potential of Vγ9Vδ2 T cells was tested by measuring proliferation in response to aminobisphosphonate zoledronic acid, and cytotoxicity against HepG2 hepatoma cell line. TCR sequencing was performed to analyse impact of HCV infection on Vδ2 T‐cell repertoire. Vγ9Vδ2 cells from patients were activated and therapy resulted in reduction of CD38 expression on these cells in SVR group. Relapsed patients had Vδ2 cells with persistently activated and terminally differentiated cytotoxic phenotype (CD38⁺CD45RA⁺CD27^?CD107a⁺). Irrespective of outcome with therapy, majority of patients had persistently poor Vδ2 T‐cell proliferative response to zoledronate along with lower expression of CD56, which identifies anti‐tumour cytotoxic subset, relative to healthy controls. There was no association between the number of antigen reactive Vγ2‐Jγ1.2 TCR rearrangements at baseline and levels of proliferation indicating nonresponse to zoledronate is not due to depletion of phosphoantigen responding chains. Thus, HCV infection results in circulating Vγ9Vδ2 T cells with a phenotype equipped for immediate effector function but poor cytokine response and expansion in response to antigen, a functional defect that may have implications for susceptibility for carcinogenesis despite HCV cure.     

Zinc transporters and their role in the pancreatic β‐cell

Zinc is an essential nutrient with tremendous importance for human health, and zinc deficiency is a severe risk factor for increased mortality and morbidity. As abnormal zinc homeostasis causes diabetes, and because the pancreatic β‐cell contains the highest zinc content of any known cell type, it is of interest to know how zinc fluxes are controlled in β‐cells. The understanding of zinc homeostasis has been boosted by the discovery of multiprotein families of zinc transporters, and one of them – zinc transporter 8 (ZnT8) – is abundantly and specifically expressed in the pancreatic islets of Langerhans. In this review, we discuss the evidence for a physiological role of ZnT8 in the formation of zinc‐insulin crystals, the physical form in which most insulin is stored in secretory granules. In addition, we cross‐examine this information, collected in genetically modified mouse strains, to the knowledge that genetic variants of the human ZnT8 gene predispose to the onset of type 2 diabetes and that epitopes on the ZnT8 protein trigger autoimmunity in patients with type 1 diabetes. The overall conclusion is that we are still at the dawn of a complete understanding of how zinc homeostasis operates in normal β‐cells and how abnormalities lead to β‐cell dysfunction and diabetes. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00199.x, 2012)     

Monitoring of local CD8β‐expressing cell populations during Eimeria tenella infection of naïve and immune chickens

The purpose of this study was to monitor abundance and activation of local CD8β‐expressing T‐cell populations during Eimeria tenella infections of naïve chickens and chickens immune by previous infections. Chickens were infected with E. tenella up to three times. Caecal T‐cell receptor (TCR) γ/δ‐CD8β+ cells (cytotoxic T lymphocytes; CTL) and TCRγ/δ+CD8β+ cells were characterized with respect to activation markers (blast transformation, CD25 and cell surface CD107a). Cells were also induced to degranulate in vitro as a measure of activation potential. Major findings included a prominent long‐lasting, up to 6 weeks, increase in the proportion of CTL among caecal CD45+ cells in the later stages after primary E. tenella infection. These CTL also showed clear signs of activation, that is blast transformation and increased in vitro induced degranulation. At second and third E. tenella infection, chickens showed strong protective immunity but discrete signs of cellular activation were observed, for example increased in vitro induced degranulation of CTL. Thus, primary E. tenella infection induced clear recruitment and activation of local CTL. Upon subsequent infections of strongly immune chickens cellular changes were less prominent, possibly due to lower overall numbers of cells being activated because of the severe restriction of parasite replication.     

The effect of α and γ-interferon on proliferation and production of IgE and β2-microglobulin in the human myeloma cell line U-266 and in an α-interferon resistant U-266 subline

An IFN-resistant subline (U-266^r_α) was established from the IFN-α-sensitive myeloma cell line U-266 by subculturing U-266 cells with increasing doses of INF-α. The U-266^r_α secreted IgE at a higher rate than the U-266 (7.2 × 10^?13 g/c/8 h as compared to 3.3 × 10^?13 g/c/8 h). The 2 cell lines were found to be equally high producers of β₂m (9.2 and 9.6 × 10^?13 g/c/8 h). The U-266 produced 2.9 times less IgE and 5 times more β₂m compared to the initial production rates at establishment. INF-α and recombinant IFN-αM₂ (rIFN-α₂) inhibited proliferation and concomitantly decreased the rate of IgE and β₂m secretion in U-266 but not in U-266 IFN^r_α, which in contrast was slightly stimulated by IFN-α with respect to growth, IgE and β₂m secretion. In addition, IFN-α at a concentration of 100 U/ml was shown to decrease the IgE and β₂m production without exerting more than minimal cytotoxicity on U-266 cells. No antiproliferative effect was found for IFN-γ or recombinant IFN-γ (rIFN-γ) on either of the 2 cell lines. IFN-γ and rIFN-γ were, however, found to stimulate the production of β₂m. Our results show that the U-266 and the derived IFN-α-resistant subline can be used as models for studying some of the biological effects of IFN-α and -γ in vitro. The clinical implications of these in vitro results, in particular the usefulness of serum determinations of immunoglobulin and β₂m concentrations for monitoring the tumor cell mass, are discussed.     

Fat‐resident Tregs: an emerging guard protecting from obesity‐associated metabolic disorders

Obesity, a chronic, low‐grade inflammatory disease, is associated with alterations of multiple immune‐cell components in the visceral adipose tissue (VAT), in which CD4⁺Foxp3⁺ regulatory T cells (Tregs) have been suggested to be a critical regulator. This review focuses on the current understanding of VAT‐resident Tregs (VAT Tregs) and their intriguing roles in modulating fat tissue inflammation and obesity‐associated metabolic disorders. The potential mechanisms for the regulation of VAT Tregs in lean vs. obese individuals are also discussed. Accumulating evidence reveals that the modulation of VAT Tregs may offer a potential novel strategy for treating obesity‐related metabolic disorders, such as insulin resistance and type 2 diabetes.     

Molecular characterization of β-thalassemia mutations in Guadeloupe

In order to perform genetic counselling and prenatal diagnosis of Hb-S-β-thalassemia disease and β-thalassemia, we have delineated the spectrum of β-thalassemia alleles in the Guadeloupean population. A sample of 63 unrelated families was analyzed including 70 β-thalassemia carriers, 52 Hb-S-β-thalassemia, and 8 patients with different β-thalassemic hemoglobinopathies. Among the eleven mutations identified, four of them [-29 (A → G), IVS-I-5 (G → A), IVS-II-1 (G → A), and IVS-I-5 (G → C)] account for 77.6% of the β-thalassemia chromosomes present in the studied families. The seven other variants, CD 24 (T → A), IVS-I-2 (T → C), Poly A (T → C), -88 (C → T), IVS-II-849 (A → G), Hb E, and Hb Lepore are less frequent. As a result, Hb S-β -thalassemia type 1 (low Hb A values: 5–15%) together with Hb S-β°-thalassemia phenotypes are as frequent as Hb S-β⁺-thalassemia type 2 (high Hb A values: 20–30%) in the Guadeloupean population. Patients with Hb S-β -thalassemia type 2 have milder hematological manifestations of the disease compared to patients with Hb S-β°-thalassemia and Hb S-β⁺-thalassemia type 1. This first report on the type and nature of β-thalassemia mutations in Guadeloupe shows that prenatal diagnosis of Hb S-β-thalassemia and β-thalassemia should be feasible by direct detection of point mutation in most cases. © 1996 Wiley-Liss, Inc.     

Differential IFN‐γ production by adult and neonatal blood CD56+ natural killer (NK) and NK‐like‐T cells in response to Trypanosoma cruzi and IL‐15

Early interferon‐gamma (IFN‐γ) release by innate cells is critical to direct type 1 immune response able to control intracellular pathogens like Trypanosoma cruzi. Although CD56^bright natural killer (NK) cells are reported to be potent early IFN‐γ producers, other CD56⁺ cells like CD56^dim NK cells and NK‐like T cells have recently been shown to also release IFN‐γ. We have here studied the contribution of each CD56⁺ lymphocyte populations in early IFN‐γ production in both adults and neonates. On this purpose, we analysed the kinetics of IFN‐γ production by RT‐PCR, ELISA and flow cytometry from 2 h onwards after T. cruzi and IL‐15 stimulation and sought for the responding CD56⁺ cells. CD56^bright and CD56^dimCD16^? NK cells were the more potent IFN‐γ early producers in response to IL‐15 and parasites in adults and neonates. In both age groups, the majority of IFN‐γ producing cells were NK cells. However, on the contrary to neonates, CD3⁺CD56⁺ NK‐like T cells and CD3⁺CD56^? ‘classical’ T cells also contributed to early IFN‐γ production in adults. Altogether, our results support that whereas NK cells responded almost similarly in neonates and adults, cord blood innate CD56⁺ and CD56^? T cells displayed major quantitative and qualitative defects that could contribute to the well‐known neonatal immune immaturity.