CARD15/NOD2 mutations are associated with susceptibility to Crohn's Disease (CD) and Graft Versus Host Disease (GVHD). CD and GVHD are suspected to be related with the dysfunction of Peyer's patches ...(PP) and isolated lymphoid follicles (LFs). Using a new mouse model invalidated for Card15/Nod2 (KO), we thus analysed the impact of the gene in these lymphoid formations together with the development of experimental colitis.
At weeks 4, 12 and 52, the numbers of PPs and LFs were higher in KO mice while no difference was observed at birth. At weeks 4 and 12, the size and cellular composition of PPs were analysed by flow cytometry and immunohistochemistry. PPs of KO mice were larger with an increased proportion of M cells and CD4(+) T-cells. KO mice were also characterised by higher concentrations of TNFalpha, IFNgamma, IL12 and IL4 measured by ELISA. In contrast, little differences were found in the PP-free ileum and the spleen of KO mice. By using chamber experiments, we found that this PP phenotype is associated with an increased of both paracellular permeability and yeast/bacterial translocation. Finally, KO mice were more susceptible to the colitis induced by TNBS.
Card15/Nod2 deficiency induces an abnormal development and function of the PPs characterised by an exaggerated immune response and an increased permeability. These observations provide a comprehensive link between the molecular defect and the Human CARD15/NOD2 associated disorders: CD and GVHD.
Background. Persistent low CD4+ cell counts are observed in 5%–27% of patients treated for human immunodeficiency virus (HIV)—1 infection despite their having prolonged undetectable plasma viral ...loads. Methods. To understand the possible mechanisms of this discordant immunological situation, a prospective transsectional case-control study was designed. HIV-1—infected subjects who had a plasma viral load <200 copies/ mL for >1 year were considered to be case patients if their CD4+ cell count was <250/mm3; control patients had CD4+ cell counts >500/mm3 and were matched by sex, age, and nadir CD4+ cell count to case patients. T cell proliferation after stimulation with various antigens, T cell subset counts, T cell rearrangement excision circles (TRECs), T cells undergoing apoptosis, cytokines influencing apoptosis, and cellular proviral DNA and plasma viral RNA persistence were assessed. Results. Compared with the 19 control patients, the 19 case patients had undistinguishable lymphoproliferative responses to candidin and cytomegalovirus, fewer naive CD4+ cells (CD45RA+62L+, 23%±13% vs. 47%±14%; P<.0001), lower thymic output (1.28 vs. 3.95 TRECs/µL of blood; P=.0015), increased cell death by apoptosis (spontaneous, 23.2%±8.3% vs. 11.9%±8.4% P=.02; Fas induced, 38.6%±13.7% vs. 16.4%±8.0% P=.004), higher levels of plasma soluble tumor necrosis factor receptor II (9.6 vs. 5.3 ng/mL; P=.0058), and undistinguishable plasma HIV-1 and cellular proviral DNA loads. Conclusions. The mechanisms responsible for the low-level regeneration of CD4+ cells involve, at least, deficiency in the regeneration of central CD4+ cells and excessive apoptosis.
Nucleotide oligomerisation domain 2 (NOD2) is a component of the innate immunity known to be involved in the homeostasis of Peyer patches (PPs) in mice. However, little is known about its role during ...gut infection in vivo. Yersinia pseudotuberculosis is an enteropathogen causing gastroenteritis, adenolymphitis and septicaemia which is able to invade its host through PPs. We investigated the role of Nod2 during Y. pseudotuberculosis infection. Death was delayed in Nod2 deleted and Crohn's disease associated Nod2 mutated mice orogastrically inoculated with Y. pseudotuberculosis. In PPs, the local immune response was characterized by a higher KC level and a more intense infiltration by neutrophils and macrophages. The apoptotic and bacterial cell counts were decreased. Finally, Nod2 deleted mice had a lower systemic bacterial dissemination and less damage of the haematopoeitic organs. This resistance phenotype was lost in case of intraperitoneal infection. We concluded that Nod2 contributes to the susceptibility to Y. pseudotuberculosis in mice.
Summary
Dravet syndrome (DS) is a refractory epileptic syndrome. Vaccination is the trigger of the first seizure in about 50% of cases. Fever remains a trigger of seizures during the course of the ...disease. We compared ex vivo cytokine responses to a combined aluminium‐adjuvanted vaccine of children with DS to sex‐ and age‐matched heathy children. Using ex vivo cytokine responses of peripheral‐blood mononuclear cells and monocytes, we found that vaccine responsiveness is biased toward a proinflammatory profile in DS with a M1 phenotype of monocytes. We provide new insight into immune mechanisms associated with DS that might guide research for the development of new immunotherapeutic agents in this epilepsy syndrome.
Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease characterized by ataxia, variously associating heart disease, diabetes mellitus and/or glucose intolerance. It results from ...intronic expansion of GAA triplet repeats at the FXN locus. Homozygous expansions cause silencing of the FXN gene and subsequent decreased expression of the encoded mitochondrial frataxin. Detailed analyses in fibroblasts and neuronal tissues from FRDA patients have revealed profound cytoskeleton anomalies. So far, however, the molecular mechanism underlying these cytoskeleton defects remains unknown. We show here that gene silencing spreads in cis over the PIP5K1B gene in cells from FRDA patients (circulating lymphocytes and primary fibroblasts), correlating with expanded GAA repeat size. PIP5K1B encodes phosphatidylinositol 4-phosphate 5-kinase β type I (pip5k1β), an enzyme functionally linked to actin cytoskeleton dynamics that phosphorylates phosphatidylinositol 4-phosphate PI(4)P to generate phosphatidylinositol-4,5-bisphosphate PI(4,5)P2. Accordingly, loss of pip5k1β function in FRDA cells was accompanied by decreased PI(4,5)P2 levels and was shown instrumental for destabilization of the actin network and delayed cell spreading. Knockdown of PIP5K1B in control fibroblasts using shRNA reproduced abnormal actin cytoskeleton remodeling, whereas over-expression of PIP5K1B, but not FXN, suppressed this phenotype in FRDA cells. In addition to provide new insights into the consequences of the FXN gene expansion, these findings raise the question whether PIP5K1B silencing may contribute to the variable manifestation of this complex disease.
Nucleotide oligomerisation domain 2 (NOD2) mutations are associated with susceptibility to Crohn's disease and graft-versus-host disease, two human disorders related with dysfunctions of Peyer's ...patches (PPs). In Nod2(-/-) mice transcellular permeability and bacterial translocation are increased in PPs. In this study, we show that both anti-CD4(+) and anti-interferon gamma (anti-IFNgamma) monoclonal antibodies abrogate this phenotype and reduce the expression of tumour necrosis factor (TNF) receptor 2 and the long isoform of myosin light chain kinase, thus demonstrating that immune T cells influence the epithelial functions. In turn, intraperitoneal injection of ML-7 (a myosin light chain kinase inhibitor) normalises the values of CD4(+) T cells, IFNgamma and TNFalpha. This reciprocal cross-talk is under the control of the gut microflora as shown by the normalisation of all parameters after antibiotic treatment. Toll-like receptor 2 (TLR2) and TLR4 expression were increased in Nod2(-/-) mice under basal conditions and TLR2 and TLR4 agonists induced an increased transcellular permeability in Nod2(+/+) mice. Muramyldipeptide (a Nod2 agonist) or ML-7 was able to reverse this phenomenon. It thus appears that Nod2 modulates the cross-talk between CD4(+) T cells and the epithelium recovering PP and that it downregulates the pro-inflammatory effect driven by the ileal microflora, likely by inhibiting the TLR pathways.
Data regarding the use of QuantiFERON to assist the diagnosis of active tuberculosis (TB) in HIV-infected children are limited, especially in countries with low incidence of TB/HIV coinfection.
...QuantiFERON results were analyzed in 63 HIV-infected children who presented to our hospital in Paris, France. Seventeen HIV-uninfected children with active TB (4 culture-confirmed) were included for comparison.
The 63 HIV-infected children (median age: 11 yr) had 113 QuantiFERON tests. Thirty-four (54%) were born in sub-Saharan Africa. Vertical HIV transmission was documented for 50 of 52 (96%) and stage III HIV-infection for 30 of 50 children (60%). Over the study period, active TB was diagnosed in 7 of 63 HIV-infected children (3 culture-confirmed). Additional ongoing or previous opportunistic infections were present in 4 of 7. QuantiFERON results were positive in 2 of 7 HIV-infected children with active TB (sensitivity: 29%) and 16 of 17 HIV-uninfected children with active TB (sensitivity: 94%). At initial QuantiFERON testing of the 63 HIV-infected children, 8 (13%) had positive results (1, active TB; 5, latent TB; 2, previous TB) and 51 (81%) had negative results. Of 33 children with repeat testing after an initially positive or negative result, the only change was one conversion from a negative to a positive result at the onset of active TB. The 4 children (6%) with indeterminate quantiFERON results had a concomitant opportunistic infection. Results of repeat testing after clinical stabilization were negative in all 4.
QuantiFERON testing performed poorly for active TB diagnosis in this series of children with advanced HIV infection.
Summary
The interplay between immune recovery, cytomegalovirus (CMV)‐reactivation, CMV‐driven immunity and graft‐versus‐leukaemia effect (GVL) was analysed in 108 children (median age: 8 years) who ...underwent haematopoietic‐stem cell transplantation (HSCT) for acute leukaemia. Follow‐up was 2 years unless death or relapse occurred. CMV‐polymerase chain reaction (PCR) was programmed weekly until month +3 post‐HSCT. Immunomonitoring consisted of sequential lymphocyte subset enumerations and analyses of T‐cell proliferative and γ‐interferon responses to CMV and to adenovirus. In the 108 recipients, the 2‐year relapse rate (RR) was 25% (median time to onset 4·5 months; range: 24 d–17 months). CMV reactivation occurrence was 31% (median time to onset 26 d). Donor/recipient CMV serostatus did not influence RR. Among the 89 recipients disease‐free after day +120, i) early CMV‐reactivation before day +30 was more frequent (P = 0·01) in the relapse recipient group opposed to the non‐relapse group. ii) CD8+/CD28− and CD4+CD45RA− T‐cell expansions induced by CMV did not influence RR, iii) Recovery of anti‐CMV and also anti‐adenovirus immunity and of naïve CD4+ T‐cells was faster in the non‐relapse group (P = 0·008; 0·009 and 0·002 respectively). In contrast to adult acute myeloid leukaemia, CMV reactivation was associated with increased RR in this paediatric series. Accelerated overall immune recovery rather than CMV‐driven immunity had a favourable impact on RR.
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