IL-10 signaling prevents gluten-dependent intraepithelial CD4+ cytotoxic T lymphocyte infiltration and epithelial damage in the small intestine.

Breach of tolerance to gluten leads to the chronic small intestinal enteropathy celiac disease. A key event in celiac disease development is gluten-dependent infiltration of activated cytotoxic intraepithelial lymphocytes (IELs), which cytolyze epithelial cells causing crypt hyperplasia and villous atrophy. The mechanisms leading to gluten-dependent small intestinal IEL infiltration and activation remain elusive. We have demonstrated that under homeostatic conditions in mice, gluten drives the differentiation of anti-inflammatory T cells producing large amounts of the immunosuppressive cytokine interleukin-10 (IL-10). Here we addressed whether this dominant IL-10 axis prevents gluten-dependent infiltration of activated cytotoxic IEL and subsequent small intestinal enteropathy. We demonstrate that IL-10 regulation prevents gluten-induced cytotoxic inflammatory IEL infiltration. In particular, IL-10 suppresses gluten-induced accumulation of a specialized population of cytotoxic CD4+CD8αα+ IEL (CD4+ CTL) expressing Tbx21, Ifng, and Il21, and a disparate non-cytolytic CD4+CD8α- IEL population expressing Il17a, Il21, and Il10. Concomitantly, IL-10 suppresses gluten-dependent small intestinal epithelial hyperproliferation and upregulation of stress-induced molecules on epithelial cells. Remarkably, frequencies of granzyme B+CD4+CD8α+ IEL are increased in pediatric celiac disease patient biopsies. These findings demonstrate that IL-10 is pivotal to prevent gluten-induced small intestinal inflammation and epithelial damage, and imply that CD4+ CTL are potential new players into these processes.

Saddlebags: A software interface for submitting full-length HLA allele sequences to the EMBL-ENA nucleotide database.

Submission of full-length HLA allele sequences presents a unique challenge, both for high-throughput sequencing laboratories and smaller diagnostic laboratories. HLA's extensive polymorphism means that accurate representation and annotation of allele sequence is of critical importance, and curators of nucleotide databases must establish submission formats to ensure high-quality data and prevent ambiguities. The IPD-IMGT/HLA database is established as the standard repository for HLA sequences, and it is a major goal of the 17th International HLA and Immunogenetics Workshop to fill the IPD-IMGT/HLA database with full-length HLA sequences. The process of preparing sequence annotation and metadata is cumbersome and error prone, and it is desirable to create a straightforward and concise method of preparing sequence submissions. We introduce Saddlebags, a software tool for rapid generation of HLA (novel) full-length allele sequence submissions. HLA allele sequences are submitted first to EMBL European Nucleotide Archive (EMBL-ENA), and metadata is gathered for subsequent preparation of an IPD-IMGT/HLA formatted submission. Combining these steps into a pipeline reduces effort and minimizes errors for submitting laboratories. This software has been used by Maastricht University Medical Center Transplantation Immunology Laboratory to submit 79 novel alleles to EMBL-ENA, and the tool is freely available for the HLA community.

Polymorphism at residue 156 of the new HLA-A*02:683 allele suggests immunological relevance.

HLA-A*02:683 is most similar to 4 different HLA-A*02 subtypes with a single nucleotide difference.

New insights in HLA-E polymorphism by refined analysis of the full-length gene.

BACKGROUND: Human leukocyte antigen (HLA)-E is a non-classical HLA class I molecule that plays a role in both the innate and the adaptive immune response through interaction with receptors on natural killer- and T-cells. The HLA-E gene is characterized by limited polymorphism compared with the classical HLA loci on chromosome 6. At the start of this study, only 13 variable sites had been identified (IPD-IMGT/HLA Database v3.18.0). While most previous studies focused on polymorphism in exons 2 and 3 or specific gene regions, polymorphism in the other exons and introns could influence protein expression and function as well. Studies that investigate extended HLA-E polymorphism are therefore needed to better understand the functional relevance of HLA-E in health and disease. AIMS: The aim of this study was to examine the variability of the full-length HLA-E gene region in individuals originating from different populations. MATERIALS AND METHODS/RESULTS: A total of 7 new HLA-E alleles were identified using full-length HLA-E sequencing of 123 individuals from Asian, Dutch or Hunan Han origin. Furthermore, genome variation analysis of the third phase of the 1000 genomes database showed 107 new variable sites in 2504 individuals originating from 26 different populations. DISCUSSION AND CONCLUSION: Our study demonstrates that the nucleotide variability of the HLA-E gene is much higher than previously known, albeit in only a limited number of individuals. Overall only 2 variants, HLA-E*01:01 and *01:03, are frequently present worldwide, suggesting that balancing selection is acting on HLA-E.

The role of gene polymorphism in HLA class I splicing.

Among the large number of human leucocyte antigen (HLA) alleles, only a few have been identified with a nucleotide polymorphism impairing correct splicing. Those alleles show aberrant expression levels, due to either a direct effect of the polymorphism on the normal splice site or to the creation of an alternative splice site. Furthermore, in several studies, the presence of alternatively spliced HLA transcripts co-expressed with the mature spliced transcripts was reported. We evaluated the splice site sequences of all known HLA class I alleles and found that, beside the consensus GT and AG sequences at the intron borders, there were some other highly conserved nucleotides for the different class I genes. In this review, we summarize the splicing mechanism and evaluate what is known today about alternative splicing of HLA class I genes.

Full-length HLA-DRB1 coding sequences generated by a hemizygous RNA-SBT approach.

Currently 1582 HLA-DRB1 alleles have been identified in the IMGT/HLA database (v3.18). Among those alleles, more than 90% have incomplete allele sequences, which complicates the analysis of the functional relevance of polymorphism beyond exon 2. The polymorphic index of each individual exon of the currently known allele sequences, shows that polymorphism is present in all exons, albeit not equally abundant. Full-length HLA-DRB1 RNA sequencing identifies polymorphism of the complete coding region. Here we describe a hemizygous full-length RNA sequence-based typing (SBT) approach based on group-specific HLA-DRB1 amplification and subsequent sequencing. RNA full-length sequences can easily be accessed because of the short amplicon length (801 bp). The RNA-SBT approach was successfully validated on a panel of DRB1 alleles having fully known coding sequences according to the IMGT/HLA database, and cover all serological equivalents. Subsequently, the approach was applied on a panel of 54 alleles with incomplete allele sequences, resulting in full-length coding sequences and the identification of one new and one corrected allele. This study shows the universal applicability of the RNA-based sequencing approach to identify full-length coding sequences and to define the polymorphic content of HLA-DRB1 alleles.

Features of a new full length HLA allele: A*02:455.

The full length sequence of HLA-A*02:455 differs from HLA-A*02:01:01:01 by one amino acid substitution: A245E.

The Maastricht Transplant Center: clinical setting and epitope searches in HLA class II molecules: does the structural localization of a polymorphic site contribute to its immunogenicity?

Our understanding of the immunological processes influencing the clinical outcome after kidney transplantation has advanced majorly over the last few decades. However, many factors still restrict graft and patient survival. Within the Maastricht transplant center we have successfully implemented an alternative immunosuppressive regimen involving Tacrolimus monotherapy in order to minimize the adverse effects associated with long-term use of immunosuppressive drugs. This clinical development has an impact on pre-transplant risk stratification which requires that patients are closely monitored immunologically. In this review we will elaborate on our strategy regarding the analysis of epitopes in HLA-DQ and HLA-DP molecules. In this respect we have also looked at the immunodominance of certain epitopes by assessing their structural localization, conformation and physiochemical properties.

An improved and validated RNA HLA class I SBT approach for obtaining full length coding sequences.

The functional relevance of human leukocyte antigen (HLA) class I allele polymorphism beyond exons 2 and 3 is difficult to address because more than 70% of the HLA class I alleles are defined by exons 2 and 3 sequences only. For routine application on clinical samples we improved and validated the HLA sequence-based typing (SBT) approach based on RNA templates, using either a single locus-specific or two overlapping group-specific polymerase chain reaction (PCR) amplifications, with three forward and three reverse sequencing reactions for full length sequencing. Locus-specific HLA typing with RNA SBT of a reference panel, representing the major antigen groups, showed identical results compared to DNA SBT typing. Alleles encountered with unknown exons in the IMGT/HLA database and three samples, two with Null and one with a Low expressed allele, have been addressed by the group-specific RNA SBT approach to obtain full length coding sequences. This RNA SBT approach has proven its value in our routine full length definition of alleles.

Allele and haplotype frequencies of HLA-DPA1 and -DPB1 in the population of Guadeloupe.

Genetic polymorphism of human leukocyte antigen (HLA)-DPA1 and -DPB1 loci was studied in 154 unrelated individuals from Guadeloupe, an archipelago of five islands located in the Carribean Sea. Thirty different DPB1 and eight different DPA1 alleles were observed with a heterozygosity index of 0.87 and 0.78, respectively. This high degree of heterozygosity corresponds with those found in African populations. The DPB1* 01:01:01 allele was most frequent (0.260), followed by 02:01:02 (0.143) and 04:01:01 (0.127). The DPA1 alleles 01:03 (0.380), 02:01 (0.302), 02:02 (0.175) and 03:01 (0.123) were identified in >35 individuals each, whereas 01:04, 01:05 and 04:01 were present only once. Haplotype estimations revealed the presence of 39 different haplotypes, with DPB1*01:01:01-DPA1*02:02 and DPB1*02:01:02-DPA1*01:03 as the most frequent (0.143 and 0.140, respectively). A striking difference was observed in DPB1/DPA1 associations between DPB1*04:02 and *105:01, that have identical exon 2 sequences. DPB1*04:02 was exclusively associated with DPA1*01:03, whereas DPB1*105:01 was present with DPA1*03:01, *03:02 or *04:01. This implies that the DP molecules are actually different, and this difference is relevant to consider in studies on the function of HLA-DP molecules in transplantation. Overall, HLA-DPA1 and DPB1 allele frequencies and haplotypes of the population of Guadeloupe were most similar to African populations, with characteristic alleles and haplotypes that bespeaks the admixture with other ethnicities.

HLA frequencies and associations in cystic fibrosis.

Cystic fibrosis (CF) is classically attributed to the dysfunction of the single CF transmembrane conductance regulator gene. The incidence of human leukocyte antigen (HLA) polymorphisms in different CF-associated diseases raises the question of an unequal distribution of HLA genotypes in CF. This study aimed to evaluate HLA gene frequencies and possible associations in CF patients compared with a control population. Frequencies of HLA-DRB1, HLA-DQA1 and HLA-DQB1, performed by intermediate resolution typing using Luminex sequence-specific oligonucleotide, and epitope counts were similar in 340 CF patients when compared with 400 control subjects. In conclusion, HLA-DRB1, -DQA1 and -DQB1 do not seem to influence susceptibility to CF. Whether HLA plays a role in the severity of CF disease needs to be investigated.

Increased production of interleukin-21, but not interleukin-17A, in the small intestine characterizes pediatric celiac disease.

Celiac disease (CD) is caused by inflammatory CD4(+) T-cell responses to dietary gluten. It is unclear whether interleukin (IL)-21 and IL-17A contribute to CD onset and lesion severity; therefore, we investigated IL-21 and IL-17A expression in biopsies from pediatric CD patients with different histopathological scores. High numbers of IL-21-producing cells were observed in pediatric CD lesions, even Marsh 1-2 lesions, whereas increased numbers of IL-17 secreting cells were not observed. Intraepithelial lymphocytes, CD4(+) T cells and also neutrophils secreted IL-21. Flow cytometry of lamina propria cells revealed a large population of IL-21- and interferon-γ (IFN-γ)-secreting CD3(+) T cells that did not secrete IL-17A. Adult CD patient biopsies also contained high numbers of IL-21-positive cells; however, enhanced numbers of IL-17-positive cells were observed in a small subgroup of patients with severe lesions. As duodenal tissue damage increases contact with microbe-associated molecular patterns, we hypothesized that microbial sensing by Toll-like receptors (TLRs) modulates T cell-derived cytokine secretion. Costimulation with TLR3 ligands during polyclonal T-cell activation significantly increased IL-21 secretion, whereas TLR2 ligands selectively enhanced IL-17A. These results demonstrate that an IL-17A-independent increase in IL-21 production by CD4(+) T cells is characteristic of pediatric CD. We hypothesize that incidental IL-17 secretion is caused by tissue damage rather than gluten-specific responses.

Full-length HLA-DPB1 diversity in multiple alleles of individuals from Caucasian, Black, or Oriental origin.

Despite DP antigens have been shown to be stimulators of the mixed lymphocyte reaction, human leukocyte antigen-DPB1 is not considered in the matching criteria for hematopoietic stem cell transplantation (HSCT). The role of DPB1 matching in HSCT remains inconclusive because of contradictory findings in different studies. The concept of permissible and non-permissible mismatches might clarify these contradictory results. Although several groups have attempted to identify immunogenic epitopes in exon 2 to establish permissive and non-permissive allele groups, the direct correlation between individual exon 2 amino acids and epitopes with DPB1 immunogenicity is still not evident. We hypothesize that polymorphism within the entire molecule, including polymorphic variability in different ethnic groups, is crucial to unravel the function of DPB1 polymorphism. Using an RNA-based approach, we sequenced all frequent and available non-frequent DPB1 alleles full length from 148 samples representing 28 different DPB1 alleles from either Black, Caucasian, or Oriental origin. We identified various DPB1 alleles with, in addition to the exon 2 polymorphism, polymorphisms in exons 1, 3, 4, and 5. Based on this polymorphism outside exon 2, we defined one new allele. Two alleles with identical exon 2 polymorphism but differing outside exon 2 were identified in individuals of different ethnic groups. As T cell binding is not restricted to the polymorphic groove and polymorphism in the ß2 domain of the DP molecule affects CD4 interaction, full-length polymorphism should be considered to determine immunogenicity. Eventually, this knowledge will provide new insights in the classification of DPB1 polymorphism and more importantly will add new perspectives to the concept of permissiveness in transplantation.

[Acute abdominal pain as the first sign of Henoch-Schönlein purpura; a hidden diagnosis in the absence of purpura]. / Acute buikpijn als eerste symptoom van Henoch-Schönlein-purpura; een verborgen diagnose als purpura ontbreekt.

2 girls with abdominal pain, aged 7 and 9 years, were admitted and underwent extensive evaluation: the first girl underwent colonoscopy and the second appendectomy, in which a negative appendix was removed. After 6 and 14 days, respectively, they developed skin lesions that did not disappear on pressure, characteristic of Henoch-Schönlein purpura (HSP). They recovered after treatment with prednisone. HSP is a systemic vasculitis, which can be diagnosed by its characteristic purpura of the skin. Diagnosis is more difficult if the patient does not present with skin lesions. HSP presenting with acute abdominal pain as an initial symptom can give rise to unnecessary additional investigation and even laparotomy. Apart from the other clinical features of HSP, i.e. bloody stools, oligo-articular arthritis and (microscopic) haematuria, diagnosis can be made earlier if biopsies of the normal skin or duodenum are taken and assessed for IgA depositions. Treatment of the abdominal pain with corticosteroids can be considered.

[From gene to disease; CD40 ligand deficiency as the cause of X-linked hyper-IgM-syndrome]. / Van gen naar ziekte; CD40-liganddeficiëntie als oorzaak van het X-gebonden hyper-IgM-syndroom.

X-linked hyper-IgM syndrome (XHIM) is a rare congenital immunodeficiency disorder, characterised by a defect in both humoral and cellular immune responses. In XHIM, the membrane glycoprotein CD40 ligand (expressed on activated T-cells) is deficient, which compromises T-cell interactions with antigen-presenting cells. Patients with XHIM present with severe, recurrent infections, predominantly of the respiratory and gastrointestinal tract. The gene encoding the CD40 ligand is located on the long arm of the X chromosome.

[Two children with severe recurrent infections and the X-linked hyper-IgM syndrome]. / Twee kinderen met ernstige, recidiverende infecties en het X-gebonden hyper-IgM-syndroom.

A boy suffered from severe recurrent intestinal infections from the age of 8 months onwards; investigation into an immune disorder ultimately resulted in the diagnosis of 'hyper-IgM syndrome'. He was treated successfully with bone marrow transplantation, using an HLA-matched donor. Another boy had severe recurrent respiratory tract infections from the age of 3 months onwards. At the age of 6.5 years, 'hyper-IgM syndrome' was diagnosed. No suitable donor was available. In addition, he developed sclerosing cholangitis and end-stage liver disease, making a combined bone marrow and liver transplantation too risky. He died at 10.5 years of age. X-linked hyper-IgM syndrome is a rare congenital immunodeficiency disorder, characterised by a defect in both humoral and cellular immune responses. Deficiency in the membrane glycoprotein CD40 ligand (expressed on activated T-cells) compromises T-cell interactions with antigen-presenting cells. In a child with severe recurrent infections, and with dysgammaglobulinaemia with a normal or increased IgM level, the diagnosis of 'X-linked hyper-IgM syndrome' should be considered.

¿Es un error médico no investigar en los pacientes cirróticos la presencia de encefalopatía hepática mínima? / Is it a medical error if we do not screen cirrhotic patients for minimal hepatic encephalopathy?

Encefalopatía hepática mínima (EHM) se refiere a defectos neurocognitivos y neurofisiológicos ligeros en pacientes con cirrosis hepática sin síntomas de encefalopatía hepática. Utilizando métodos diagnósticos adecuados la prevalencia es aproximadamente entre un 25 y 30 por ciento. EHM tiene un significado clínico ya que es motivo de una disminución de la actividad cotidiana, precede a la encefalopatía hepática franca, y está asociada con un mal pronóstico. El tratamiento con disacaridasas no absorbibles puede revertir los defectos neurocognitivos y neurofisiológicos encontrados en EHM. Por eso, el fallo de no diagnosticar EHM en pacientes cirróticos aparentemente normales, podría considerarse como un error médico. Sin embargo todavía queda por determinar sí el tratamiento mejora la calidad de vida y el pronóstico del paciente (AU)

Is it a medical error if we do not screen cirrhotic patients for minimal hepatic encephalopathy?

Minimal hepatic encephalopathy (MHE) refers to subtle neurocognitive and neurophysiological defects in patients with liver cirrhosis without clinical signs of hepatic encephalopathy. Using appropriate diagnostic methods the prevalence of MHE is approximately 25-30%. MHE has clinical significance as it results in a diminished daily functioning, precedes overt hepatic encephalopathy and is associated with a poor prognosis. Treatment with non-absorbable disaccharides can reverse the neurocognitive and neurophysiological defects found in MHE. The failure to diagnose MHE in apparently normal cirrhotic patients could, therefore, be considered a medical error. However, whether treatment also improves patients' quality of life and prognosis remains to be determined.

The prognostic significance of subclinical hepatic encephalopathy.

OBJECTIVE: Subclinical hepatic encephalopathy may have prognostic significance with regard to the development of clinical hepatic encephalopathy and survival. METHODS: We studied 116 consecutive patients with histologically proven cirrhosis of the liver for subclinical hepatic encephalopathy, using Number Connection Test A, Digit Symbol Test, and spectral analysis of the electroencephalogram. RESULTS: Twenty-five patients (22%) were diagnosed as having subclinical hepatic encephalopathy. Patients with subclinical hepatic encephalopathy were older, had a higher Child-Pugh score, and more often had esophageal or gastric varices and episode(s) of clinical hepatic encephalopathy in their history. During a median follow-up of 29 months (range, 1-49 months), patients with subclinical hepatic encephalopathy significantly more often had episodes of clinical hepatic encephalopathy; survival, however, was similar to that of patients without subclinical hepatic encephalopathy, and was determined mainly by the Child-Pugh score. The Child-Pugh score was also superior to subclinical hepatic encephalopathy in predicting episodes of clinical hepatic encephalopathy. CONCLUSIONS: The prognostic significance of subclinical hepatic encephalopathy appears limited.

Screening of subclinical hepatic encephalopathy.

BACKGROUND/AIMS: Subclinical hepatic encephalopathy adversely affects daily functioning. The aim of this study was to determine which elements of daily life have predictive value for subclinical hepatic encephalopathy. METHODS: The study was performed in 179 outpatients with liver cirrhosis. Subclinical hepatic encephalopathy was diagnosed using psychometric tests with normal values corrected for age (Number Connection Test A and the Digit Symbol Test) and automated analysis of the electroencephalogram (EEG). Daily functioning was measured with the Sickness Impact Profile (SIP), a quality of life questionnaire, containing 136 statements. Patients with and without SHE were compared for differences in response to all statements by univariate analysis, and subsequently by multivariate analysis of potential discriminating statements. RESULTS: SHE was diagnosed in 48 patients (27%). Thirty-six statements were significantly more often true for patients with subclinical hepatic encephalopathy. Multivariate analysis showed that five statements of the SIP, related to alertness, sleep and rest, fine motor skills and work, have independent predictive power for subclinical hepatic encephalopathy. CONCLUSION: Combining these statements predictive for subclinical hepatic encephalopathy with patient characteristics enables physicians to assess the probability of subclinical hepatic encephalopathy in the individual cirrhotic patient at the bedside or in the outpatient clinic.