RÉSUMÉ
The processes leading from disturbed B-cell development to adult B-cell progenitor acute lymphoblastic leukemia (BCP-ALL) remain poorly understood. Here, we describe Irf4-/- mice as prone to developing BCP-ALL with age. Irf4-/- preB-I cells exhibited impaired differentiation but enhanced proliferation in response to IL-7, along with reduced retention in the IL-7 providing bone marrow niche due to decreased CXCL12 responsiveness. Thus selected, preB-I cells acquired Jak3 mutations, probably following irregular AID activity, resulting in malignant transformation. We demonstrate heightened IL-7 sensitivity due to Jak3 mutants, devise a model to explain it, and describe structural and functional similarities to Jak2 mutations often occurring in human Ph-like ALL. Finally, targeting JAK signaling with Ruxolitinib in vivo prolonged survival of mice bearing established Irf4-/- leukemia. Intriguingly, organ infiltration including leukemic meningeosis was selectively reduced without affecting blood blast counts. In this work, we present spontaneous leukemogenesis following IRF4 deficiency with potential implications for high-risk BCP-ALL in adult humans.
Sujet(s)
Lymphome de Burkitt , Leucémie-lymphome lymphoblastique à précurseurs B et T , Adulte , Animaux , Humains , Souris , Lymphocytes B , Lymphome de Burkitt/anatomopathologie , Interleukine-7/génétique , Janus kinase 3/génétique , Mutation/génétique , Leucémie-lymphome lymphoblastique à précurseurs B et T/génétique , Transduction du signalSujet(s)
Vaccin BNT162 , Lymphocytes T , Adulte , Anticorps neutralisants , Anticorps antiviraux , Humains , SARS-CoV-2 , VaccinationRÉSUMÉ
Here we compared SARS-CoV-2-specific antibody and T-cell responses between older adults (>80 years old, n = 51) and a younger control group (20-53 years old, n = 46) after receiving two doses of BNT162b2. We found that responses in older adults were generally lower, and we identified 10% low-/non-responders. After receiving a third vaccination with BNT162b2, 4 out of 5 low-/non-responders showed antibody and T-cell responses similar to those of responders after two vaccinations.
Sujet(s)
Anticorps antiviraux/sang , Vaccin BNT162/immunologie , COVID-19/prévention et contrôle , Immunité cellulaire , Immunité humorale , Immunogénicité des vaccins , SARS-CoV-2/immunologie , Adulte , Facteurs âges , Sujet âgé de 80 ans ou plus , Anticorps neutralisants/sang , Vaccin BNT162/administration et posologie , COVID-19/immunologie , Humains , Rappel de vaccin/méthodes , Rappel de vaccin/statistiques et données numériques , Immunoglobuline G/sang , Adulte d'âge moyen , Tests de neutralisation , Lymphocytes T/immunologie , Jeune adulteRÉSUMÉ
We found that deletion of the final 30 amino acids of transcription factor IRF4's (interferon-regulatory factor) C-terminus creates hyperactive IRF4. When introduced into IRF4-deficient CD4+ or CD8+ T cells, more type 17 differentiation was found compared to WT IRF4. Interestingly, Th9 differentiation and Th2-linked IL-13 production were much less altered.
Sujet(s)
Facteurs de régulation d'interféron/génétique , Mutation , Sous-populations de lymphocytes T/métabolisme , Animaux , Humains , Facteurs de régulation d'interféron/métabolisme , Sous-populations de lymphocytes T/immunologieRÉSUMÉ
Activated T cells produce reactive oxygen species (ROS), which trigger the antioxidative glutathione (GSH) response necessary to buffer rising ROS and prevent cellular damage. We report that GSH is essential for T cell effector functions through its regulation of metabolic activity. Conditional gene targeting of the catalytic subunit of glutamate cysteine ligase (Gclc) blocked GSH production specifically in murine T cells. Gclc-deficient T cells initially underwent normal activation but could not meet their increased energy and biosynthetic requirements. GSH deficiency compromised the activation of mammalian target of rapamycin-1 (mTOR) and expression of NFAT and Myc transcription factors, abrogating the energy utilization and Myc-dependent metabolic reprogramming that allows activated T cells to switch to glycolysis and glutaminolysis. In vivo, T-cell-specific ablation of murine Gclc prevented autoimmune disease but blocked antiviral defense. The antioxidative GSH pathway thus plays an unexpected role in metabolic integration and reprogramming during inflammatory T cell responses.
Sujet(s)
Glutamate-cysteine ligase/déficit , Glutathion/métabolisme , Inflammation/métabolisme , Lymphocytes T/métabolisme , Animaux , Encéphalomyélite auto-immune expérimentale/génétique , Encéphalomyélite auto-immune expérimentale/métabolisme , Métabolisme énergétique/génétique , Glutamate-cysteine ligase/génétique , Glutamine/métabolisme , Glycolyse , Immunotransfert , Inflammation/génétique , Souris de lignée C57BL , Souris knockout , Facteurs de transcription NFATC/métabolisme , Protéines proto-oncogènes c-myc/métabolisme , Espèces réactives de l'oxygène/métabolisme , Transduction du signal/génétique , Sérine-thréonine kinases TOR/métabolismeRÉSUMÉ
The genus leishmania comprises different protozoan parasites which are causative agents of muco-cutaneous and systemic, potentially lethal diseases. After infection with the species Leishmania major, resistant mice expand Th1 cells which stimulate macrophages for Leishmania destruction. In contrast, susceptible mice generate Th2 cells which deactivate macrophages, leading to systemic spread of the pathogens. Th-cell differentiation is determined within the first days, and Th2 cell differentiation requires IL-4, whereby the initial IL-4 source is often unknown. Mast cells are potential sources of IL-4, and hence their role in murine leishmaniasis has previously been studied in mast cell-deficient Kit mutant mice, although these mice display immunological phenotypes beyond mast cell deficiency. We therefore readdressed this question by infecting Kit-independent mast cell-deficient mice that are Th1 (C57BL/6 Cpa(Cre) ) or Th2 (BALB/c Cpa(Cre) ) prone with L. major. Using different parasite doses and intra- or subcutaneous infection routes, the results demonstrate no role of mast cells on lesion size development, parasite load, immune cell phenotypes expanding in draining lymph nodes, and cytokine production during murine cutaneous leishmaniasis. Thus, other cell types such as ILCs or T cells have to be considered as primary source of Th2-driving IL-4.
Sujet(s)
Leishmaniose cutanée/immunologie , Mastocytes/immunologie , Lymphocytes auxiliaires Th2/immunologie , Animaux , Différenciation cellulaire/immunologie , Modèles animaux de maladie humaine , Prédisposition aux maladies , Leishmania major , Leishmaniose cutanée/parasitologie , Activation des lymphocytes/immunologie , Souris , Souris de lignée BALB C , Souris de lignée C57BL , Souches mutantes de souris , Charge parasitaireRÉSUMÉ
Regulatory T-cells induced via IL-2 and TGFß in vitro (iTreg) suppress immune cells and are potential therapeutics during autoimmunity. However, several reports described their re-differentiation into pathogenic cells in vivo and loss of their key functional transcription factor (TF) FOXP3 after T-cell antigen receptor (TCR)-signalling in vitro. Here, we show that TCR-activation antagonizes two necessary TFs for foxp3 gene transcription, which are themselves regulated by phosphorylation. Although the tyrosine phosphatase PTPN2 is induced to restrain IL-2-mediated phosphorylation of the TF STAT5, expression of the TF FOXO1 is downregulated and miR-182, a suppressor of FOXO1 expression, is upregulated. TGFß counteracts the FOXP3-depleting TCR-signal by reassuring FOXO1 expression and by re-licensing STAT5 phosphorylation. Overexpressed phosphorylation-independent active versions of FOXO1 and STAT5 or knockdown of PTPN2 restores FOXP3 expression despite TCR-signal and absence of TGFß. This study suggests novel targets for stabilisation and less dangerous application of iTreg during devastating inflammation.
Sujet(s)
Facteurs de transcription Forkhead/métabolisme , Protein Tyrosine Phosphatase, Non-Receptor Type 2/métabolisme , Récepteurs aux antigènes des cellules T/métabolisme , Lymphocytes T régulateurs/métabolisme , Animaux , Technique de Western , Lymphocytes T CD4+/métabolisme , Cellules cultivées , Femelle , Cytométrie en flux , Protéine O1 à motif en tête de fourche , Facteurs de transcription Forkhead/génétique , Mâle , Souris , Protein Tyrosine Phosphatase, Non-Receptor Type 2/génétique , Récepteurs aux antigènes des cellules T/génétiqueRÉSUMÉ
BACKGROUND: For effective control of visceral leishmaniasis (VL) in East Africa, new rapid diagnostic tests are required to replace current tests with low sensitivity. The aim of this study is to improve diagnosis of VL in East Africa by testing a new antigen from an autochthonous L. donovani strain in Sudan. METHODOLOGY AND PRINCIPLE FINDINGS: We cloned, expressed and purified a novel recombinant protein antigen of L. donovani from Sudan, designated rKLO8, that contains putative conserved domains with significant similarity to the immunodominant kinesin proteins of Leishmania. rKLO8 exhibited 93% and 88% amino acid identity with cloned kinesin proteins of L. infantum (synonymous L. chagasi) (K39) and L. donovani (KE16), respectively. We evaluated the diagnostic efficiency of the recombinant protein in ELISA for specific detection of VL patients from Sudan. Data were compared with a rK39 ELISA and two commercial kits, the rK39 strip test and the direct agglutination test (DAT). Of 106 parasitologically confirmed VL sera, 104 (98.1%) were tested positive by rKLO8 as compared to 102 (96.2%) by rK39. Importantly, the patients' sera showed increased reactivity with rKLO8 than rK39. Specificity was 96.1% and 94.8% for rKLO8- and rK39 ELISAs, respectively. DAT showed 100% specificity and 94.3% sensitivity while rK39 strip test performed with 81.1% sensitivity and 98.7% specificity. CONCLUSION: The increased reactivity of Sudanese VL sera with the rKLO8 makes this antigen a potential candidate for diagnosis of visceral leishmaniasis in Sudan. However, the suitability at the field level will depend on its performance in a rapid test format.
Sujet(s)
Anticorps antiprotozoaires/sang , Antigènes de protozoaire , Tests diagnostiques courants/méthodes , Leishmania donovani/immunologie , Leishmaniose viscérale/diagnostic , Protéines de protozoaire , Tests d'agglutination/méthodes , Antigènes de protozoaire/génétique , ADN des protozoaires/composition chimique , ADN des protozoaires/génétique , Test ELISA/méthodes , Humains , Leishmania donovani/génétique , Données de séquences moléculaires , Protéines de protozoaire/génétique , Protéines recombinantes/génétique , Sensibilité et spécificité , Analyse de séquence d'ADN , SoudanRÉSUMÉ
Follicular T-helper (T(FH)) cells cooperate with GL7(+)CD95(+) germinal center (GC) B cells to induce antibody maturation. Herein, we identify the transcription factor IRF4 as a T-cell intrinsic precondition for T(FH) cell differentiation and GC formation. After immunization with protein or infection with the protozoon Leishmania major, draining lymph nodes (LNs) of IFN-regulatory factor-4 (Irf4(-/-)) mice lacked GCs and GC B cells despite developing normal initial hyperplasia. GCs were also absent in Peyer's patches of naive Irf4(-/-) mice. Accordingly, CD4(+) T cells within the LNs and Peyer's patches failed to express the T(FH) key transcription factor B-cell lymphoma-6 and other T(FH)-related molecules. During chronic leishmaniasis, the draining Irf4(-/-) LNs disappeared because of massive cell death. Adoptive transfer of WT CD4(+) T cells or few L. major primed WT T(FH) cells reconstituted GC formation, GC B-cell differentiation, and LN cell survival. In support of a T-cell intrinsic IRF4 activity, Irf4(-/-) T(FH) cell differentiation was not rescued by close neighborhood to transferred WT T(FH) cells. Together with its known B lineage-specific roles during plasma cell maturation and class switch, our study places IRF4 in the center of antibody production toward T-cell-dependent antigens.