[Genetic study of a rare Chinese pedigree with a recombination occurring between the HLA-A/C loci in both parents].

OBJECTIVE: To analyze a Chinese pedigree with a recombination occurring between the HLA-A/C loci in both parents. METHODS: A patient who was planning to undergo hematopoietic stem cell transplantation due to "aplastic anemia" in February 2022 was selected as the study subject. Peripheral blood samples were collected from the patient, his parents and brother. HLA-A/C/B/DRB1/DQB1 high-resolution typing was carried out by using sequence-based typing and sequence-specific oligonucleotides. The recombination was identified by pedigree analysis. The HLA haplotype of each individual was identified by genealogical analysis. The parentage possibility was determined by short tandem repeat analysis. HLA-A/C/B/DRB1/DRB345/DQA1/DQB1/DPA1/DPB1 were determined with next-generation high-throughput sequence-based typing. The recombination sites were analyzed by family study. RESULTS: The high parentage possibilities of the family was confirmed by short tandem repeat analysis. Recombination was found between the HLA-A*24:02 A*33:03/C*14:03 in the paternally transmitted haplotype, whilst HLA-A*01:01 A*03:01/C*08:02 was found in the maternally transmitted haplotype, which had resulted in two novel HLA haplotypes in the proband. CONCLUSION: A rare case with simultaneous recombination of the paternal and maternal HLA-A/C loci has been discovered, which may facilitate further study of the mechanisms of the HLA recombination.

The novel HLA-C*04:01:01:182 allele identified in a candidate bone marrow donor by next-generation sequencing.

HLA-C*04:01:01:182 differs from the HLA-C*04:01:01:06 allele by one nucleotide substitution in the 5'UTR.

The novel HLA-C*14:02:01:31 allele identified in a candidate bone marrow donor by next-generation sequencing.

Characterisation of the novel HLA-C*14:02:01:31 allele in a 21-year-old Greek bone marrow donor.

HLA-C expression in extravillous trophoblasts is determined by an ELF3-NLRP2/NLRP7 regulatory axis.

The distinct human leukocyte antigen (HLA) class I expression pattern of human extravillous trophoblasts (EVT) endows them with unique tolerogenic properties that enable successful pregnancy. Nevertheless, how this process is elaborately regulated remains elusive. Previously, E74 like ETS transcription factor 3 (ELF3) was identified to govern high-level HLA-C expression in EVT. In the present study, ELF3 is found to bind to the enhancer region of two adjacent NOD-like receptor (NLR) genes, NLR family pyrin domain-containing 2 and 7 (NLRP2, NLRP7). Notably, our analysis of ELF3-deficient JEG-3 cells, a human choriocarcinoma cell line widely used to study EVT biology, suggests that ELF3 transactivates NLRP7 while suppressing the expression of NLRP2. Moreover, we find that NLRP2 and NLRP7 have opposing effects on HLA-C expression, thus implicating them in immune evasion at the maternal-fetal interface. We confirmed that NLRP2 suppresses HLA-C levels and described a unique role for NLRP7 in promoting HLA-C expression in JEG-3. These results suggest that these two NLR genes, which arose via gene duplication in primates, are fine-tuned by ELF3 yet have acquired divergent functions to enable proper expression levels of HLA-C in EVT, presumably through modulating the degradation kinetics of IkBα. Targeting the ELF3-NLRP2/NLRP7-HLA-C axis may hold therapeutic potential for managing pregnancy-related disorders, such as recurrent hydatidiform moles and fetal growth restriction, and thus improve placental development and pregnancy outcomes.

Identification of a novel HLA-C allele, HLA-C*02:246.

HLA-C*02 246 has one nucleotide change from HLA-C*02:02:02:01 at nucleotide 523 changing Arginine to Cysteine at residue 151.

Helicobacter pylori enhances HLA-C expression in the human gastric adenocarcinoma cells AGS and can protect them from the cytotoxicity of natural killer cells.

Helicobacter pylori (H. pylori) seems to play causative roles in gastric cancers. H. pylori has also been detected in established gastric cancers. How the presence of H. pylori modulates immune response to the cancer is unclear. The cytotoxicity of natural killer (NK) cells, toward infected or malignant cells, is controlled by the repertoire of activating and inhibitory receptors expressed on their surface. Here, we studied H. pylori-induced changes in the expression of ligands, of activating and inhibitory receptors of NK cells, in the gastric adenocarcinoma AGS cells, and their impacts on NK cell responses. AGS cells lacked or had low surface expression of the class I major histocompatibility complex (MHC-I) molecules HLA-E and HLA-C-ligands of the major NK cell inhibitory receptors NKG2A and killer-cell Ig-like receptor (KIR), respectively. However, AGS cells had high surface expression of ligands of activating receptors DNAM-1 and CD2, and of the adhesion molecules LFA-1. Consistently, AGS cells were sensitive to killing by NK cells despite the expression of inhibitory KIR on NK cells. Furthermore, H. pylori enhanced HLA-C surface expression on AGS cells. H. pylori infection enhanced HLA-C protein synthesis, which could explain H. pylori-induced HLA-C surface expression. H. pylori infection enhanced HLA-C surface expression also in the hepatoma Huh7 and HepG2 cells. Furthermore, H. pylori-induced HLA-C surface expression on AGS cells promoted inhibition of NK cells by KIR, and thereby protected AGS cells from NK cell cytotoxicity. These results suggest that H. pylori enhances HLA-C expression in host cells and protects them from the cytotoxic attack of NK cells expressing HLA-C-specific inhibitory receptors.

HLA peptide-binding pocket diversity modulates immunological complications after cord blood transplant in acute leukaemia.

Pocket motifs and their amino acid positions of HLA molecules are known to govern antigen presentation to effector cells. Our objective was to analyse their influence on the risk of graft-versus-host disease (GVHD) and relapse after umbilical cord blood transplant (UCBT). The transplant characteristics of 849 patients with acute leukaemia were obtained from the Eurocord/EBMT database. Higher acute (a) GVHD was associated with homozygosity of UCB HLA-C amino acid positions 77 and 80 (NN/KK) (p = 0.008). Severe aGVHD was associated with HLA-A pocket B YSAVMENVHY motif (p = 0.002) and NN and RR genotypes of the HLA-C amino acid positions 77 and 156 (p = 0.006 and p = 0.002). Such risk was also increased in case of recipient and UCB mismatches in P4 (p < 0.0001) and P9 (p = 0.003) pockets of HLA-DQB1 alleles. For chronic GVHD, the pocket B YYAVMEISNY motif of the HLA-B*15:01 allele and the absence of mismatch between recipient and UCB in the P6 pocket of HLA-DRB1 were associated with a lower risk (p = 0.0007 and p = 0.0004). In relapse, both UCB pocket B YFAVMENVHY belonging to HLA-A*32:01 and recipient pocket B YDSVGENYQY motif of the HLA-C*07:01 allele were associated with higher risk (p = 0.0026 and p = 0.015). We provide clues on HLA-mediated cellular interactions and their role in the development of GVHD and relapse.

The novel HLA-C*12:392 allele was identified in four unrelated bone marrow donors.

One nucleotide substitution in codon 83 of HLA-С*12:02:02:01 results in the novel allele, HLA-C*12:392.

Determination of the Relationship Between the Development and Recurrence of Subacute Thyroiditis and Human Leukocyte Antigen Subtypes.

Background: There are several studies investigating the role of human leukocyte antigens (HLA) in the development and recurrence of subacute thyroiditis (SAT). The HLA subtypes associated with SAT were usually determined in a population-based manner and HLA-B*35, HLA-B*18:01, HLA-C*04:01, and HLA-DRB1*01 were detected to play a role in the disease susceptibility and prognosis. The aim of this study was to determine HLA alleles associated with the tendency of recurrence and prevention of SAT within the Turkish population. Methods: This prospective study was conducted with 51 SAT patients and 720 healthy bone marrow donor volunteers. HLA-A, -B, -C, -DRB1, and -DQB1 were genotyped using next-generation sequencing. Results: The frequency of HLA-A*02:09, HLA-B*35:01/35:02/35:03, HLA-C*04:01, HLA-DRB1*12:01, and DRB1*13:03 were associated with an increased risk of SAT development (Odds Ratio: 22.4, 9.5, 10.3, 4.2, and 3.5, respectively). While HLA-A*02:09, HLA-B*35:01, HLA-B*44:02 HLA-C*07:18, and HLA-C*16:04 were associated with nonrelapsing SAT, HLA-DR*12:01was associated with relapsing SAT. HLA-B*35:02, HLA-B*35:03, and HLA-C*04:01 were more frequent both in relapsing and nonrelapsing groups according to control group. The frequency of HLA-B*18:01, reported as a risk factor previously, was similar in the SAT and control groups (p = 0.959). HLA-DRB1*11:01 was associated with a lower risk of SAT development. Conclusions: Along with -B*358 and -C*04, HLA-A*02:09 was detected as an important risk factor for SAT development in our population. HLA-DRB1*11:01 appears to be the protective HLA subtype against SAT. HLA-A*02:09, HLA-B*35:01, HLA-B*44:02, HLA-C*07:18, HLA-C*16:04, HLA-DQ*06:03, and HLA-DR*12:01 subtypes can establish a tendency to relapsing or nonrelapsing SAT.

Lack of association between alopecia areata and HLA class I and II in a southeastern Brazilian population

Abstract: Background: Alopecia areata (AA) is a common disorder of unknown etiology that affects approximately 0.7% to 3.8% of patients among the general population. Currently, genetic and autoimmune factors are emphasized as etiopathogenic. Studies linking Human Leukocyte Antigens (HLA) to AA have suggested that immunogenetic factors may play a role in the disease's onset/development. Objectives: To investigate an association between AA and HLA class I/II in white Brazilians. Methods: Patients and control groups comprised 33 and 112 individuals, respectively. DNA extraction was performed by column method with BioPur kit. Allele's classification was undertaken using the PCR-SSO technique. HLA frequencies were obtained through direct counting and subjected to comparison by means of the chi-square test. Results: Most patients were aged over 16, with no familial history, and developed partial AA, with no recurrent episodes. Patients showed a higher frequency of HLA-B*40, HLA-B*45, HLA-B*53 and HLA-C*04 compared with controls, although P was not significant after Bonferroni correction. Regarding HLA class II, only HLA-DRB1*07 revealed statistical significance; nevertheless, it featured more prominently in controls than patients (P=0.04; Pc=0.52; OR=0.29; 95%; CI=0.07 to 1.25). P was not significant after Bonferroni correction. Conclusions: The development of AA does not seem to be associated with HLA in white Brazilians, nor with susceptibility or resistance. The studies were carried out in populations with little or no miscegenation, unlike the Brazilian population in general, which could explain the inconsistency found.

The role of KIR2DL3/HLA-C*0802 in Brazilian patients with rheumatoid vasculitis

OBJECTIVES: Rheumatoid arthritis is a polygenically controlled systemic autoimmune disease. Rheumatoid vasculitis is an important extra-articular phenotype of rheumatoid arthritis that can result in deep cutaneous ulcers. The objective of this study was to establish a correlation between the frequency of major histocompatibility complex class I/II alleles and killer immunoglobulin-like receptor genotypes in patients with cutaneous rheumatoid vasculitis. METHODS: Using the Scott & Bacon 1984 criteria to diagnose rheumatoid vasculitis and after excluding any other causes such as diabetes, atherosclerosis, adverse drug reactions, infection, and smoking, patients who met the criteria were selected. All of the selected rheumatoid vasculitis patients presented deep cutaneous ulcers. Identification of the major histocompatibility complex class I/II and killer immunoglobulin-like receptor genotypes was performed by polymerase chain reaction assays of samples collected from the 23 rheumatoid vasculitis patients as well as from 80 controls (40 non-rheumatoid vasculitis RA control patients and 40 healthy volunteers). RESULTS: An association between the presence of the HLA-DRB1*1402 and HLA-DRB1*0101 alleles and cutaneous lesions in rheumatoid vasculitis patients and a correlation between the inhibitor KIR2DL3 and the HLA-C*0802 ligand in rheumatoid vasculitis patients were found. CONCLUSION: An association was found between the presence of the HLA-DRB1*1402 and HLA-DRB1*0101 alleles and the development of cutaneous lesions in rheumatoid vasculitis patients. Additionally, the HLA-C*0802 ligand protects these individuals from developing cutaneous lesions. .

Antígenos HLA asociados con retinopatía diabética en pacientes insulino-dependientes / HLA antígens associated with diabetic retinopathy in patients insulin-dependents

Se ha sugerido que el alotipo DR4 es un marcador genético que predispone a la Retinopatía Diabética y es considerado como factor que confiere susceptibilidad para la forma proliferativa. Para investigar esta asociación se estudiaron diéz (10) pacientes diabéticos insulino-dependiente a quienes se les tipificaron los haplotipos HLA A-B-C y D. La presencia de retinopatía se evidenció por la evaluación del fondo de ojo. Los resultados obtenidos demuestran que existe una asociación entre la aparición de la retinopatía y el número de años de evolución de la diábetes mellitus y entre la presencia de al menos un alelo 4 en el loci DR y la Retinopatía Diabética