MHC Variants Associated With Symptomatic Versus Asymptomatic SARS-CoV-2 Infection in Highly Exposed Individuals.

Despite the high number of individuals infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who develop coronavirus disease 2019 (COVID-19) symptoms worldwide, many exposed individuals remain asymptomatic and/or uninfected and seronegative. This could be explained by a combination of environmental (exposure), immunological (previous infection), epigenetic, and genetic factors. Aiming to identify genetic factors involved in immune response in symptomatic COVID-19 as compared to asymptomatic exposed individuals, we analyzed 83 Brazilian couples where one individual was infected and symptomatic while the partner remained asymptomatic and serum-negative for at least 6 months despite sharing the same bedroom during the infection. We refer to these as "discordant couples". We performed whole-exome sequencing followed by a state-of-the-art method to call genotypes and haplotypes across the highly polymorphic major histocompatibility complex (MHC) region. The discordant partners had comparable ages and genetic ancestry, but women were overrepresented (65%) in the asymptomatic group. In the antigen-presentation pathway, we observed an association between HLA-DRB1 alleles encoding Lys at residue 71 (mostly DRB1*03:01 and DRB1*04:01) and DOB*01:02 with symptomatic infections and HLA-A alleles encoding 144Q/151R with asymptomatic seronegative women. Among the genes related to immune modulation, we detected variants in MICA and MICB associated with symptomatic infections. These variants are related to higher expression of soluble MICA and low expression of MICB. Thus, quantitative differences in these molecules that modulate natural killer (NK) activity could contribute to susceptibility to COVID-19 by downregulating NK cell cytotoxic activity in infected individuals but not in the asymptomatic partners.

HLA-G is upregulated in advanced endometriosis.

OBJECTIVE: To assess whether the HLA-G immunomodulatory protein is potentially involved in the pathophysiology of endometriosis or disease progression. STUDY DESIGN: Cross-sectional observational study of 227 women who underwent laparoscopy, being 146 for endometriosis excision and 81 for elective tubal ligation (control group). Soluble HLA-G (sHLA-G) levels in the serum and peritoneal fluid (PF), as well as the HLA-G protein expression in matched eutopic and ectopic endometrium of women with and without endometriosis were evaluated by ELISA and immunohistochemistry assays, respectively. Women with endometriosis were separated into groups according to the initial (I/II, n = 60) and advanced (III/IV, n = 86) stages of disease. sHLA-G measurement was performed only in women with matched serum and PF samples in both the control (CTRL; n = 77) and endometriosis (EDT; I-II, n = 60; III-IV, n = 83) groups. HLA-G protein expression was evaluated in 26 women with deep endometriosis (I-II, n = 12; III-IV, n = 14) and 22 controls. RESULTS: Higher concentrations of sHLA-G (P = 0.013) in the serum but not in the PF were observed in women with advanced endometriosis compared to the control group. In situ expression of HLA-G protein was also higher in ectopic (P = 0.018) but not in eutopic endometrium of women with advanced endometriosis compared to control group. CONCLUSION: Our findings suggest that HLA-G upregulation in advanced stages may contribute to the state of immunosuppression in endometriosis as disease progresses.

High rate of clinical recurrence in patients with Vogt-Koyanagi-Harada disease treated with early high-dose corticosteroids.

PURPOSE: To analyse the rate of clinical recurrences in Brazilian patients with Vogt-Koyanagi-Harada (VKH) disease after early high-dose corticosteroid treatment. METHODS: Retrospective study including patients treated with early high-dose corticosteroids (prednisone, 1-1.5 mg/kg/day, or 3-day 1 g methylprednisolone pulsetherapy) within 1 month from disease onset followed by slow taper (at least 6 months). Patients with a minimum 12-month follow-up were subdivided based on the presence of disease recurrence or persistence after 6 months from initial presentation into: acute-resolved (AR, no recurrences), chronic-recurrent (CR), and chronic-recurrent with subretinal fibrosis (SRF). Recurrences were defined as the presence of clinical and/or fluorescein angiography findings. RESULTS: Twenty-nine patients (58 eyes) with a median follow-up of 65 months were included. Six (21 %), 11 (38 %) and 12 (41 %) patients were allocated to AR, CR, and SRF groups respectively. Though having received treatment within 1 month of onset, median time to initial treatment differed among groups (11, 15, and 25 days, in AR, CR, and SRF groups respectively). Intensity of immunosuppression, cataract development, and longer time to achieve logMAR visual acuity ≤0.8 differed significantly among the groups, being more severe in SRF group. HLA-DRB1*0405 allele followed the same trend, though not reaching significance (0.5 in AR group, 0.6 in CR, and 0.8 in SRF). CONCLUSION: VKH disease in Brazilian patients evolved to chronic-recurrent disease in 79 % of cases; 38 % developed subretinal fibrosis, in spite of similar initial treatment regimens. Time to initiate treatment influenced outcomes.

Autoimmune hepatitis, HLA and extended haplotypes.

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease. Characteristic liver-infiltrating immune cells in portal and periportal areas, hypergammaglobulinemia and typical autoantibodies indicate an ongoing autoimmune reaction against liver self antigens, which lead to irreversible cellular damage and ultimately to severe hepatic failure. A significant part of adult, but not pediatric AIH patients, exhibit concurrent autoimmune diseases, further strengthening the immunological etiology of the disease. Genetic susceptibility to autoimmune hepatitis is strongly associated with HLA-DRB1 alleles. In Caucasian European and North American patients, AIH-1 is associated with the presence of DRB1*0301, DRB3*0101 and DRB1*0401 alleles, while AIH-2 is associated with DRB1*0301 or DRB1*07. In Brazil, the primary susceptibility allele for AIH-1 is DRB1*1301, but a secondary association with DRB1*0301 has also been identified. We looked for additional susceptibility factors in the extended MHC region. We genotyped 107 AIH-1 children and up to 326 healthy subjects for TNFA G-308A, TNFA G-238A, LTA A+252G, LTA A+80C, NFKBIL1 T-63A, BAT1 C-348T, BAT1 G-22C, MICA, and HLA-B polymorphisms. The TNFA-308 A allele was significantly increased in AIH-1 when compared with healthy controls, confirming data from other studies. Linkage disequilibrium analysis was carried out. The ancestral haplotype comprising TNFA-308A, TNFA-238G, LTA+252G, LTA+80C, NFKBIL1-63A, BAT1-348C, BAT1-22C, HLA-B*08, MICA*08 was more common in DRB1*03 positive patients than in controls (40% vs. 14%), showing a seven-fold increased risk for the disease [OR=7.8 (95%CI 2.04-29.9.2, p=0.0021). In contrast, the remaining patients carrying DRB1*03 exhibited varied haplotypes. Finally, a variety of class III haplotypes was also present in HLA-DRB1*13 patients, without a predominant pattern. The most common of the 98 haplotypes present in patients were completely absent in controls. The extended haplotype analysis in this sample of AIH-1 patients highlights not only the genetic diversity present in the Brazilian population, but is also in accordance with the previously documented microdiversity within the MHC region. The present knowledge of AIH suggests that the same or a very similar disease can be induced by yet unknown, but different, triggers followed by presentation on different HLA-DR molecules of the epitopes derived from the corresponding autoantigens, characterizing a much more complex disease than previously thought.

Identification of multiple HLA-A*0201-restricted cruzipain and FL-160 CD8+ epitopes recognized by T cells from chronically Trypanosoma cruzi-infected patients.

Chronic Chagas disease occurs in 16 million individuals chronically infected by the protozoan Trypanosoma cruzi in Latin America, and may lead to a dilated cardiomyopathy in 10-30% of patients. A vigorous cellular immune response holds parasitism in check. However, up to now, few T. cruzi proteins have been shown to be recognized by CD8+ T cells from Chagas disease patients. In this study, we designed 94 peptides derived from T. cruzi proteins cruzipain and FL-160, predicted to bind to HLA-A2 molcules. After in vitro binding assays to HLA-A*0201, 26 peptides were selected, and their recognition by PBMC from Chagas disease patients was tested with the IFN-gamma ELISPOT assay. All 26 peptides were recognized by PBMC from at least one patient. Furthermore, a tetrameric HLA-A*0201 complex built with the cruzipain 60-68 peptide that was frequently recognized in the periphery also bound to CD8+ T cells from a heart-infiltrating T cell line obtained from a single patient with Chagas disease cardiomyopathy. Thus, our results suggest that the recognition of CD8+ T cell epitopes in cruzipain and FL-160 may have a pathogenic or protective role in chronic Chagas disease.

Análise comparativa da determinaçäo de antígenos HLA-DR por métodos sorológicos e por PCR-SSP / Comparative analysis of the HLA-DR antigen determination by serologic methods and by PCR-SSP

O objetivo deste trabalho foi comparar a determinaçäo dos antígenos HLA-DR por sorologia, utilizando-se A) anti-soros policlonais ou B) anticorpos monoclonais, com a determinaçäo em nível de DNA em amostras de sangue de receptores e doadores de rim e medula óssea. Observamos que os anticorpos monoclonais apresentam maior concordância com o PCR-SSP. Podemos concluir que as determinaçöes sorológicas têm menor precisäo, acarretando aproximadamente 48 por cento de imprecisoes com anti-soros policlonais e 21 por cento com anticorpos monoclonais. O PCR-SSP permite melhor definiçäo da compatibilidade HLA-DR entre receptor e doador, o que será, em última análise, adjuvante de melhor sobrevida do enxerto.