Naturally occurring Toll-like receptor 11 (TLR11) and Toll-like receptor 12 (TLR12) polymorphisms are not associated with Toxoplasma gondii infection in wild wood mice

Toxoplasma gondii is a highly successful parasite with a worldwide prevalence. Small rodents are the main intermediate hosts, and there is growing evidence that T. gondii modifies their behaviour. Chronically infected rodents show impaired learning capacity, enhanced activity, and, most importantly, a reduction of the innate fear towards cat odour. This modification of host behaviour ensures a successful transmission of T. gondii from rodents to felids, the definitive hosts of the parasite. Given the negative fitness consequences of this behavioural manipulation, as well as an increased mortality during the acute phase of infection, we expect rodents to evolve potent resistance mechanisms that prevent or control infection. Indeed, studies in laboratory mice have identified candidate genes for T. gondii resistance. Of particular importance appear to be the innate immune receptors Toll-like receptor 11 (TLR11) and Toll-like receptor 12 (TLR12), which recognise T. gondii profilin and initiate immune responses against the parasite.Here we analyse the genetic diversity of TLR11 and TLR12 in a natural population of wood mice (Apodemus sylvaticus), and test for associations between TLR11 and TLR12 polymorphisms and T. gondii infection, as well as for epistatic interactions between TLR11 and TLR12 on infection status. We found that both TLR11 and TLR12 were polymorphic in wood mice, with four and nine amino acid haplotypes, respectively. However, we found no evidence that TLR11 or TLR12 genotypes or haplotypes were significantly associated with Toxoplasma infection. Despite the importance of TLR11 and TLR12 in T. gondii recognition and immune defence initiation, naturally occurring polymorphisms at TLR11 and TLR12 thus appear to play a minor role in mediating qualitative resistance to T. gondii in natural host populations of A. sylvaticus. This highlights the importance of assessing the role of candidate genes for parasite resistance identified in a laboratory setting in an ecologically meaningful context to quantify their role in mediating host–parasite interactions in the wild.     

T-cell receptor constant beta chain polymorphisms and susceptibility to type 1 diabetes.

Several groups have previously shown that the T-cell receptor (TCR) constant-beta (C beta) chain locus is associated with susceptibility to Type 1 diabetes, although other studies have failed to show this. We have extended these studies by investigating 125 individuals with Type 1 diabetes and failed to confirm the significantly increased frequency of the 10;9.2 kb TCR-C beta/Bgl-II genotype in our patient population. However, further analysis showed that the 10;9.2 kb TCR-C beta genotype was significantly increased in those patients with no microvascular complications after 20 years of diabetes compared to those patients with complications (proteinuria, overt neuropathy, and moderate or severe retinopathy) 69.2% vs 31.7%, respectively, p < 0.005 Pc = 0.025). Similar results were also found in a second group of 74 patients who were analysed in the same way. Hence, the failure of some investigators to confirm the association between TCR-C beta and Type I diabetes may be due to heterogeneity in the patient populations being studied.     

Genetic diversity of HLA system in six populations from Jalisco,Mexico: Guadalajara city,Tlajomulco, Tlaquepaque,Tonalá, Zapopan and rural Jalisco

We studied HLA class I (HLA-A, -B) and class II (HLA-DRB1, -DQB1) alleles by PCR-SSP based typing in 2046 Mexicans from the state of Jalisco living in the city of Guadalajara (N = 1189), Tlajomulco (N = 30), Tlaquepaque (N = 39), Tonalá (N = 35), Zapopan (N = 168) and rural communities (N = 585), to obtain information regarding allelic and haplotypic frequencies. We find that the most frequent haplotypes found in the state of Jalisco include nine Native American most probable ancestry and three European haplotypes. Admixture estimates revealed that the main genetic components in the state of Jalisco are European (48.45 ± 1.18% by ML; 41.66% of European haplotypes) and Native American (44.02 ± 1.24% by ML; 39.86% of Native American haplotypes), while African genetic component is less apparent (7.53 ± 0.30% by ML; 9.62% of African haplotypes).     

Immunogenetics of the Lennox-Gastaut Syndrome: Frequency of HL-A Antigens and Haplotypes in Patients and First-Degree Relatives

Twenty-two patients with the Lennox-Gastaut syndrome and their families were examined for HL-A antigens by the microlymphocytotoxicity test. The antigen HL-A7 belonging to the HL-A locus showed a significantly increased frequency (p less than 0.0005) both in parents and in patients. The same antigen showed a significantly altered segregation in patients but a normal one in healthy siblings. Another antigen of the second HL-A locus, HL-A12, did not display a normal segregation in our patients, in whom it was nearly not represented.     

A reverse-engineering strategy utilizing the integration of single antigen beads and NGS HLA genotypes to detect potential antibody inducing epitopes

Central to the idea of antibody recognition is some degree of foreignness of the target antigen compared to the antibody producer. Epitopes are distinct regions on an antigen to which antibody can be elicited and bound. However, for HLA antigens, there is no consensus definition of what represents the minimal functional immunogenic unit of dissimilarity. To assess this in an unbiased way, we developed a reverse engineering software strategy based on donor specific antibodies defined by single antigen beads and full length genomic high resolution HLA typing by NGS of recipients and donors (332 transplant pairs). Starting with the ATG of Exon 1 and moving stepwise one amino acid at a time for each of the following triplets, the algorithm compared every possible amino acid triplet of the recipient and donor for 11 loci (A, B, C, DRB1, DRB3, DRB4, DRB5, DQA1, DQB1, DPA1, DPB1). Results were agnostic with respect to HLA class, not restricted to just the mature protein, and not influenced by existing maps (e.g., IMGT, or epitope models). We also developed web-based functions in the 17th IHIWS database to collect the unbiased triplets so that we could group the transplant pairs with the same donor specific antibodies and find shared triplets within the groups as potential core or essential epitopes that trigger the antibody formation. Profiling the pairs where the same DSA was identified led to identification of discrete amino acid triplets shared among the pairs irrespective of HLA match. The potential epitopes were mapped onto the 3D protein structure for reference.     

Genetic diversity of CD14, CD28, CTLA-4 and ICOS gene promoter polymorphism in African and American sickle cell disease

Variable immune response to external stimuli remains a major concern in sickle cell disease (SCD), with such responses predicted to be contributors to disease pathogenesis. Elucidating the diversity of host genes contributing to immune response would assist to clarify differing outcomes among and between disease groups. We hypothesize that there is a significant interethnic diversity in the CD14 (rs2569190), CD28 (rs35593994), CTLA-4 (rs5742909) and ICOS (rs4404254) gene polymorphisms among and between SCD groups. We genotyped single nucleotide polymorphisms of the 4 loci among African and African American SCD and control groups and between SCD groups. In all, 375 individuals from Mali (145 SCD and 230 controls) and 700 DNA samples from the United States (321 SCD and 379 controls) were subjected to a PCR-RFLP assay. We found no intraethnic difference in genotypic and allelic frequencies of the 4 loci among Africans and African Americans, potentially significant in disease association studies, including a similar observation for interethnic frequencies of CD28, CTLA-4 and ICOS genes, but not CD14. The CD14 (rs2569190) gene promoter demonstrated a significant difference (p < 0.02) between African and African American SCD groups, with the mutant variant (−159 T/T) more frequent (p < 0.0002) in African American SCD (38.9% versus 26.2%). The higher frequency of CD14 mutants among African Americans without an accompanying defect in CD28, CTLA-4 and ICOS diversity possibly indicates a defective innate response, driven by CD14, is untethered to downstream T cell differentiation or effector function. Additionally, we show that CD28 (rs35593994) mutant variants have no impact on T cell differentiation, as the ICOS gene provides an alternative pathway to override this impairment. We conclude that in spite of the defect in CD14, T cell selection and differentiation is unimpeded and a robust adaptive immune response initiated.     

Influence of HLA-DQ Matching on Allograft Outcomes in Deceased Donor Kidney Transplantation

Background and Objectives

HLA matching at the A, B, and DR loci influences the graft survival rate of deceased donor kidney transplants. The effect of HLA-DQB1 matching on transplant outcomes is still controversial. The aim of this study was to investigate the association of HLA-DQB1 matching with allograft outcomes in deceased donor kidney transplant recipients.

Multigenic control of measles vaccine immunity mediated by polymorphisms in measles receptor, innate pathway, and cytokine genes

Measles infection and vaccine response are complex biological processes that involve both viral and host genetic factors. We have previously investigated the influence of genetic polymorphisms on vaccine immune response, including measles vaccines, and have shown that polymorphisms in HLA, cytokine, cytokine receptor, and innate immune response genes are associated with variation in vaccine response but do not account for all of the inter-individual variance seen in vaccinated populations. In the current study we report the findings of a multigenic analysis of measles vaccine immunity, indicating a role for the measles virus receptor CD46, innate pattern-recognition receptors (DDX58, TLR2, 4, 5, 7 and 8) and intracellular signaling intermediates (MAP3K7, NFKBIA), and key antiviral molecules (VISA, OAS2, MX1, PKR) as well as cytokines (IFNA1, IL4, IL6, IL8, IL12B) and cytokine receptor genes (IL2RB, IL6R, IL8RA) in the genetic control of both humoral and cellular immune responses. This multivariate approach provided additional insights into the genetic control of measles vaccine responses over and above the information gained by our previous univariate SNP association analyses.