Genetic association between a ‘standing’ variant of NOD2 and bipolar disorder

Bipolar disorders (BD) are chronic, multisystem and multifactorial disorders with significant lifetime morbidity, mortality and socio-economic burden. Understanding the underlying genetic and disease triggering environmental factors should improve diagnosis, prognosis, prevention and therapeutic management of the disease. Since intestinal innate dysimmunity seems to play a significant role in the etiopathogeny of BD, we explored in a sample of French Caucasian BD patients, the genetic polymorphisms of NOD2 (nucleotide-binding oligomerization domain containing 2) gene, a key player in such immunity. We found a Caucasian-specific ‘standing’ variation to be associated with BD. The significance of this finding is discussed in the context of Crohn's disease as well as the complex function of NOD2 in innate immunity.     

Use of gene-modified regulatory T-cells to control autoimmune and alloimmune pathology: Is now the right time?

Adoptive immunotherapy using genetically targeted T-cells has recently begun to achieve impressive clinical impact in selected tumor types. Furthermore, long-term follow-up studies indicate thus far that integrating viral vectors do not elicit clinically evident genotoxicity in T-cells, unlike hematopoietic stem cells. The optimism engendered by this clinical experience provides a platform for consideration of the extended use of this technology in other disease types. One area of particular interest entails the harnessing of regulatory T-cells (Tregs) in order to down-regulate unwanted immune responses. Increasing evidence supports the efficacy of this approach in pre-clinical models of autoimmune disease and allograft rejection. Nonetheless, questions remain about optimal host cell, transgene cargo, phenotypic stability of engineered cells in vivo and potential for toxicity. Here, we review the evidence that genetically engineered Tregs can effectively dampen pathogenic immune responses and critically evaluate the prospects for clinical development of this approach.     

Identification of a novel HLA-G+ regulatory population in blood: expansion after allogeneic transplantation and de novo HLA-G expression at graft-versus-host disease sites

Background The human leukocyte antigen-G (HLA-G) has been considered to be an important tolerogeneic molecule playing an essential role in maternal-fetal tolerance, which constitutes the perfect example of successful physiological immunotolerance of semi-allografts. In this context, we investigated the putative role of this molecule in the allogeneic hematopoietic cell transplantation setting. DESIGN AND METHODS: The percentage of HLA-G(+) cells in peripheral blood of healthy donors and allo-transplanted patients was evaluated by flow cytometry. Their immunoregulatory and tolerogeneic properties were investigated in in vitro immunostimulatory and immunosuppression assays. Immunohistochemical analysis for HLA-G expression was performed in skin biopsies from allo-transplanted patients and correlated with the occurrence of graft-versus-host disease. RESULTS: We identified a CD14(+)HLA-G(pos) population with an HLA-DR(low) phenotype and decreased in vitro immunostimulatory capacity circulating in peripheral blood of healthy individuals. Naturally occurring CD14(+)HLA-G(pos) cells suppressed T-cell responses and exerted an immunotolerogenic action on T cells by rendering them hyporesponsive and immunosuppressive in vitro. After allogeneic hematopoietic cell transplantation, HLA-G(pos) cells increase in blood. Interestingly, besides an increase in CD14(+)HLA-G(pos) cells, there was also a pronounced expansion of CD3(+)HLA-G(pos) cells. Of note, CD3(+)HLA-G(pos) and CD14(+)HLA-G(pos) cells from transplanted patients were suppressive in in vitro lymphoproliferation assays. Furthermore, we found an upregulation of HLA-G expression in skin specimens from transplanted patients that correlated with graft-versus-host disease. Inflammatory cells infiltrating the dermis of transplanted patients were also HLA-G(pos). Conclusions We report the presence of naturally occurring HLA-G(pos) monocytic cells with in vitro suppressive properties. HLA-G expressing regulatory blood cells were found in increased numbers after allogeneic transplantation. Epithelial cells in skin affected by graft-versus-host disease revealed elevated HLA-G expression.     

Histological and immunohistochemical characterisation of conjunctival graft vs host disease following haematopoietic stem cell transplantation

Background Conjunctival graft vs host disease (cnGvHD) is a complication of haematopoietic stem cell transplantation, in most cases as part of systemic GvHD. Diagnostic biopsies are commonly collected from bulbar conjunctiva only. The aims of our study were to evaluate whether additional biopsies from the tarsal conjunctiva increase sensitivity upon histopathologic evaluation and to investigate the staining profile for common immunohistochemical markers in cnGvHD. We additionally propose an adaptive histological classification for cnGvHD analogous to Lerner’s GvHD skin classification for predicting patient survival. Methods Formalin-fixed and paraffin-embedded conjunctival specimens from 23 post-mortem control eyes and 42 patients after haematopoietic stem cell transplantation (HSCT) were stained with haematoxylin and eosin (HE), periodic acid–Schiff (PAS) stain and with antibodies against CD1a, CD4, CD8, CD25, CD45RO, CD68, Fas ligand, TIA-1, HLA-DRα by means of immunohistochemistry. Cell counting took place in ten representative fields at 64.4 μm (length) × 21.2 μm (width). Multifactorial analysis of variance was performed to assess any influence of cnGvHD on the staining pattern for the immunohistochemical markers. Survival times were estimated by the Kaplan–Meier method. Results All 42 specimens and none of the controls were diagnosed as cnGvHD. The bulbar specimens were staged according to the modified Lerner classification: grade (G) I: 0; G II: 17 (tarsal with G≤II, 2; G>II, 8); G III: 12 (tarsal with G≤III: 2; G>III: 1); G IV: 12 (tarsal with G≤IV: 6); G V: 1. The number of pairs with either the tarsal or bulbar counterpart being more severely affected was almost equal (10 vs 9). A tendency towards shorter survival in advanced bulbar cnGvHD was demonstrated (G III–V vs G I–II, p =0.06). Staining for the immunohistochemical markers in cnGvHD differed significantly from that in controls (p<0.01). Proposed markers for cnGvHD (e = epithelium, s = stroma; mean cell counts ± SD; cnGvHD vs controls) are: CD8 s (15.7 ± 18.4 vs 6 ± 5.6), CD25 s (2.6 ± 2.8 vs 0.7 ± 1.6), CD68 s (8 ± 9 vs 3.9 ± 3.5) at the bulbar site and CD1a e (1.2 ± 1.6 vs 0.3 ± 0.6) and TIA-1 e (2.2 ± 2.2 vs 1.1 ± 1.3) at the tarsal site. Conclusions Additional tarsal biopsy does not seem to add relevant diagnostic sensitivity for cnGvHD when the modified Lerner classification is applied. The modified Lerner classification of the bulbar cnGvHD seems to be of prognostic value. Parts of this work were presented as a poster at the DOG meeting 2005.     

Long-term follow-up of IPEX syndrome patients after different therapeutic strategies: An international multicenter retrospective study

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Predicting an HLA-DPB1 expression marker based on standard DPB1 genotyping: Linkage analysis of over 32,000 samples

The risk of acute graft-versus-host disease (GvHD) after hematopoietic stem cell transplantation is increased with donor-recipient HLA-DPB1 allele mismatching. The single-nucleotide polymorphism (SNP) rs9277534 within the 3′ untranslated region (UTR) correlates with HLA-DPB1 allotype expression and serves as a marker for permissive HLA-DPB1 mismatches. Since rs9277534 is not routinely typed, we analyzed 32,681 samples of mostly European ancestry to investigate if the rs9277534 allele can be reliably imputed from standard DPB1 genotyping. We confirmed the previously-defined linkages between rs9277534 and 18 DPB1 alleles and established additional linkages for 46 DPB1 alleles. Based on these linkages, the rs9277534 allele could be predicted for 99.6% of the samples based on DPB1 genotypes (99.99% concordance). We demonstrate that 100% prediction accuracy could be achieved if the prediction utilized exon 3 sequence information. DPB1 genotyping based on exon 2 data alone allows no unambiguous rs9277534 allele prediction but was estimated to maintain 99% accuracy for samples of European descent. We conclude that DPB1 genotyping is sufficient to infer the DPB1 expression marker rs9277534 with high accuracy. This information could be used to select donors with permissive HLA-DPB1 mismatches without directly screening for rs9277534.     

L‐Selectin Is Dispensable for T Regulatory Cell Function Postallogeneic Bone Marrow Transplantation

In murine models, the adoptive transfer of CD4⁺/CD25⁺ regulatory T cells (T_regs) inhibited graft‐versus‐host disease (GvHD). Previous work has indicated a critical role for the adhesion molecule L‐selectin (CD62L) in the function of T_regs in preventing GvHD. Here we examined the capacity of naive wild‐type (WT), CD62L^?/? and ex vivo expanded CD62L^Lo T_regs to inhibit acute GvHD. Surprisingly, we found that CD62L^?/? T_regs were potent suppressors of GvHD, whereas CD62L^Lo T_regs were unable to inhibit disease despite being functionally competent to suppress allo T cell responses in vitro. Concomitant with improved outcomes, WT and CD62L^?/? T_regs significantly reduced liver pathology and systemic pro‐inflammatory cytokine production, although CD62L^?/? T_regs were less effective in reducing lung pathology. While accumulation of CD62L^?/? T_regs in GvHD target organs was equivalent to WT T_regs, CD62L^?/? T_regs did not migrate as well as WT T_regs to peripheral lymph nodes (PLNs) over the first 2 weeks posttransplantation. This work demonstrated that CD62L was dispensable for T_reg‐mediated protection from GvHD.     

Activation of the aryl hydrocarbon receptor reduces the number of precursor and effector T cells,but preserves thymic CD4CD25Foxp3 regulatory T cells

Aryl hydrocarbon receptor (AhR) activation suppresses immune responses, including allergic sensitization, by increasing the percentage of regulatory (Treg) cells. Furthermore, AhR activation is known to affect thymic precursor T cells. However, the effect of AhR activation on intrathymic CD4⁺CD25⁺Foxp3⁺ Treg cells is unknown. Therefore, we investigated the effect of AhR activation on the percentage and number of CD4⁺CD25⁺Foxp3⁺ Treg cells during allergic sensitization in relevant immunological organs.