Evolution and molecular interactions of major histocompatibility complex (MHC)-G, -E and -F genes.

Classical HLA (Human Leukocyte Antigen) is the Major Histocompatibility Complex (MHC) in man. HLA genes and disease association has been studied at least since 1967 and no firm pathogenic mechanisms have been established yet. HLA-G immune modulation gene (and also -E and -F) are starting the same arduous way: statistics and allele association are the trending subjects with the same few results obtained by HLA classical genes, i.e., no pathogenesis may be discovered after many years of a great amount of researchers' effort. Thus, we believe that it is necessary to follow different research methodologies: (1) to approach this problem, based on how evolution has worked maintaining together a cluster of immune-related genes (the MHC) in a relatively short chromosome area since amniotes to human at least, i.e., immune regulatory genes (MHC-G, -E and -F), adaptive immune classical class I and II genes, non-adaptive immune genes like (C2, C4 and Bf) (2); in addition to using new in vitro models which explain pathogenetics of HLA and disease associations. In fact, this evolution may be quite reliably studied during about 40 million years by analyzing the evolution of MHC-G, -E, -F, and their receptors (KIR-killer-cell immunoglobulin-like receptor, NKG2-natural killer group 2-, or TCR-T-cell receptor-among others) in the primate evolutionary lineage, where orthology of these molecules is apparently established, although cladistic studies show that MHC-G and MHC-B genes are the ancestral class I genes, and that New World apes MHC-G is paralogous and not orthologous to all other apes and man MHC-G genes. In the present review, we outline past and possible future research topics: co-evolution of adaptive MHC classical (class I and II), non-adaptive (i.e., complement) and modulation (i.e., non-classical class I) immune genes may imply that the study of full or part of MHC haplotypes involving several loci/alleles instead of single alleles is important for uncovering HLA and disease pathogenesis. It would mainly apply to starting research on HLA-G extended haplotypes and disease association and not only using single HLA-G genetic markers.

HLA in Las Alpujarras Mts., South-East Spain: A Renaissance process of population artificial substitution.

Spain was invaded in 711 CE by mostly Berber North Africans carrying Muslim religion to a mostly Christian/Catholic Kingdom. A fight to expel Muslims soon started and were apparently driven out of Iberia (Spain) starting in 1492 CE. However, many of these expelled people were of Iberian old ancestry that had become Muslims at Las Alpujarras Mts. (South-East Spain). Also, Muslim North Africans converted to Christianity either remained there or came back after they more definetively were expelled by 1609 CE. Las Alpujarras region was also repopulated by northern Spaniards mostly from Galicia. Our HLA study of present day Alpujarrans shows that typical North Spain and European Atlantic façade HLA extended haplotypes are very frequent in nowadays Las Alpujarras region, i. e.: HLA-(A*29-B*44)-DRB1*07:01-DQA1*02:01-DQB1*02:01 and (A*02-B*27)-DRB1*15:01-DQA1*01:02-DQB1*06:02. It is concluded that repopulation had a noticeable success even in today Alpujarran population.

HLA-G: Too Much or Too Little? Role in Cancer and Autoimmune Disease.

HLA-G is a non-classical HLA class I molecule with immunomodulatory properties. It was initially described at the maternal-fetal interface, and it was later found that this molecule was constitutively expressed on certain immuneprivileged tissues, such as cornea, endothelial and erythroid precursors, and thymus. The immunosuppressive effect of HLA-G is exerted through the interaction with its cognate receptors, expressed on immunocompetent cells, like ILT2, expressed on NK, B, T cells and APCs; ILT4, on APCs; KIR, found on the surface of NK cells; and finally, the co-receptor CD8. Because of these immunomodulatory functions, HLA-G has been involved in several processes, amongst which organ transplantation, viral infections, cancer progression, and autoimmunity. HLA-G neo-expression on tumors has been recently described in several types of malignancies. In fact, tumor progression is tightly linked to the presence of the molecule, as it exerts its tolerogenic function, inhibiting the cells of the immune system and favoring tumor escape. Several polymorphisms in the 3'UTR region condition changes in HLA-G expression (14bp and +3142C/G, among others), which have been associated with both the development and outcome of patients with different tumor types. Also, in recent years, several studies have shown that HLA-G plays an important role in the control of autoimmune diseases. The ability of HLA-G to limit the progression of these diseases has been confirmed and, in fact, levels of the molecule and several of its polymorphisms have been associated with increased susceptibility to the development of autoimmune diseases, as well as increased disease severity. Thus, modulating HLA-G expression in target tissues of oncology patients or patients with autoimmune diseases may be potential therapeutic approaches to treat these pathological conditions.

HLA-G in Mayas from Yucatan: An evolutionary approach.

HLA-G allele frequencies were studied in Yucatán (Mexico) Maya Amerindians by a direct exon DNA sequencing technique. It is described that Mayas are probably one of the first populations together with Olmecs that populated Meso America and that important HLA genetic differences between Mexican and Guatemalan Mayas support that Maya languages were imposed to several neighbouring Amerindian groups. HLA-G*01:01:02, HLA-G*01:01:01 and HLA-G*01:04:01 are the most frequent alleles in this population. It is remarkable that HLA-G*01:05N allele was not found in the population in accordance with similar results found in another Amerindians. Also, protein allele HLA-G*01:04 frequency is found not to differ to those found in another far or close living Amerindians in contrast to other World populations. It seems that while high HLA-G*01:05N frequency is found in Iran and Middle East populations, probably where this allele appeared within an ancestral HLA-A*19 group of alleles haplotype and it is maintained by unknown evolutionary forces, Amerindians do not have a high frequency because a founder effect or because required natural evolutionary forces do not exist in America. Finally, we believe useful to study HLA-G evolution for its physiopathology understanding in addition to the many papers on statistics on HLA-G and in vitro models that are yearly published.

Impact of the Polymorphism rs9264942 near the HLA-C Gene on HIV-1 DNA Reservoirs in Asymptomatic Chronically Infected Patients Initiating Antiviral Therapy.

Several genome-wide association studies have identified a polymorphism located 35 kb upstream of the coding region of HLA-C gene (rs9264942; termed -35 C/T) as a host factor significantly associated with the control of HIV-1 viremia in untreated patients. The potential association of this host genetic polymorphism with the viral reservoirs has never been investigated, nor the association with the viral control in response to the treatment. In this study, we assess the influence of the polymorphism -35 C/T on the outcome of virus burden in 183 antiretroviral-naïve HIV-1-infected individuals who initiated antiviral treatment (study STIR-2102), analyzing HIV-1 RNA viremia and HIV-1 DNA reservoirs. The rs9264942 genotyping was investigated retrospectively, and plasma levels of HIV-1 RNA and peripheral blood mononuclear cell- (PBMC-) associated HIV-1 DNA were compared between carriers and noncarriers of the protective allele -35 C before antiretroviral therapy (ART), one month after ART and at the end of the study (36 months). HIV-1 RNA and HIV-1 DNA levels were both variables significantly different between carriers and noncarriers of the allele -35 C before ART. HIV-1 DNA levels remained also significantly different one month posttherapy. However, this protective effect of the -35 C allele was not maintained after long-term ART.

[Poliovirus immunology: vaccines, problems for the prevention/eradication and future interventions]. / Inmunología de la poliomielitis: vacunas, problemas para la prevención/erradicación e intervenciones de futuro.

Polio is a contagious disease that is caused by the poliovirus, an enterovirus in the family Picornaviridae. The virus enters through the oral mucosa and multiplies in epithelial cells of both the oropharynx as the gastrointestinal tract, releasing virus in oropharyngeal secretions and through the stool. The mode of transmission is fecal-oral and/or oral-oral. The virus preferentially infects children under 5 years. Most infections are asymptomatic and self-limiting gastrointestinal tract. Eventually it spreads to the central nervous system and affects the anterior horn motor neurons of the spinal cord causing paralysis and even death. We will describe host-virus interaction and the natural history of infection which depends on many factors, including the type of viral inoculum (serotypes VP1, 2 and 3) and host factors, such as nutritional status, concurrent infections and the ability to induce protective immune responses, such as, humoral anti-viral antibody responses with neutralizing antibodies, mucosal immunity and systemic adaptative immune responses. We will discuss the relevant aspects of the immuno-pathogenesis of the infection by poliovirus and the problems related to the host-virus interactions in the subjects vaccinated, with the latest advances in the strategies to develop optimal protection with the different poliovirus vaccines that could allow the development of a more effective immunization with induction of the effect or mechanisms that would prevent development of the disease, transmission of the virus, out-breaks and eventually the poliovirus eradication.

Inmunología de la poliomielitis: vacunas, problemas para la prevención/erradicación e intervenciones de futuro / Poliovirus immunology: vaccines, problems for the prevention/eradication and future interventions

La poliomielitis es una enfermedad infecto-contagiosa que afecta preferentemente a los niños menores de 5 años y está causada por el poliovirus, un enterovirus perteneciente a la familia Picornaviridae. El virus entra a través de la mucosa oral y se multiplica en las células del epitelio tanto de la orofaringe como del tracto gastrointestinal, liberando virus a nivel de las secreciones orofaríngeas y a través de la materia fecal. La vía de transmisión es fecal-oral y/o oral-oral. La mayoría de los casos de infección son asintomáticos y autolimitados al tracto gastrointestinal. Eventualmente puede diseminarse al sistema nervioso central y afectar a las motoneuronas del asta anterior de la médula espinal ocasionando parálisis e incluso la muerte. El curso natural de la infección depende de múltiples factores, como el tipo de inóculo viral (serotipos VP1, 2 y 3) y factores del huésped/sistema inmunológico, que incluye el estado nutricional, las infecciones concurrentes y la capacidad de inducir respuestas inmunológicas protectoras sistémicas de tipo humoral, con anticuerpos anti-víricos circulantes neutralizantes, y respuestas de la inmunidad de mucosas y adaptativa. Discutiremos los aspectos actuales de la inmunopatogénesis de la infección por el poliovirus, la interacción huésped-virus y la eficacia y los problemas en el desarrollo de las estrategias con las diferentes vacunas anti-poliovirus, para que la inmunización sea más efectiva en relación a la inducción de los mecanismos protectores que evitan el desarrollo de la enfermedad, la transmisión del virus, los rebrotes de infección y eventualmente facilitan la consecución de su erradicación (AU)

Polio is a contagious disease that is caused by the poliovirus, an enterovirus in the family Picornaviridae. The virus enters through the oral mucosa and multiplies in epithelial cells of both the oropharynx as the gastrointestinal tract, releasing virus in oropharyngeal secretions and through the stool. The mode of transmission is fecal-oral and/or oral-oral. The virus preferentially infects children under 5 years. Most infections are asymptomatic and self-limiting gastrointestinal tract. Eventually it spreads to the central nervous system and affects the anterior horn motor neurons of the spinal cord causing paralysis and even death. We will describe host-virus interaction and the natural history of infection which depends on many factors, including the type of viral inoculum (serotypes VP1, 2 and 3) and host factors, such as nutritional status, concurrent infections and the ability to induce protective immune responses, such as, humoral anti-viral antibody responses with neutralizing antibodies, mucosal immunity and systemic adaptative immune responses. We will discuss the relevant aspects of the immuno-pathogenesis of the infection by poliovirus and the problems related to the host-virus interactions in the subjects vaccinated, with the latest advances in the strategies to develop optimal protection with the different poliovirus vaccines that could allow the development of a more effective immunization with induction of the effector mechanisms that would prevent development of the disease, transmission of the virus, out-breaks and eventually the poliovirus eradication (AU)

Prognostic value of peripheral blood mononuclear cell-associated HIV-1 DNA for virological outcome in asymptomatic HIV-1 chronic infection.

BACKGROUND: Studies in primary HIV-1 infection and advanced HIV-1 disease have demonstrated that HIV-1 DNA associated with peripheral blood mononuclear cells (PBMC HIV-1 DNA) has predictive value for disease progression. OBJECTIVES: To analyse in asymptomatic HIV-1 chronic infection the predictive value of PBMC HIV-1 DNA for virological failure. STUDY DESIGN: In 115 individuals who had previously participated in study STIR-2102, we retrospectively analysed the PBMC HIV-1 DNA by quantitative real-time PCR. Antiretroviral naïve patients (baseline pre-ART) received 6 weeks of ART prior to randomisation (baseline post-ART). The predictive value of PBMC HIV-1 DNA, HIV-1 RNA in plasma and CD4+ T cells, at baselines pre-ART and post-ART, was determined by Kaplan-Meier and Proportional Hazards Regression analyses. RESULTS: At baseline post-ART, 82% of patients showed suppression of HIV-1 RNA, however they maintained significant amounts of HIV-1 DNA (geometric mean: 690 copies/10(6) PBMC). Pre-ART and post-ART levels of HIV-1 DNA and pre-ART levels of HIV-1 RNA showed predictive value (Log-Rank test: p<0.001, p<0.001, p=0.003, respectively). In a multivariate model post-ART PBMC HIV-1 DNA was the stronger predictive variable (adjusted HR, 2.51 [95% CI, 1.33-4.73, p=0.004]) independently of HIV-1 RNA (HR 1.74 [95% CI, 1.16-2.61, p=0.007]). CONCLUSIONS: PBMC HIV-1 DNA is an effective prognostic marker for virological outcome in individuals with asymptomatic HIV-1 chronic infection.

Risk factors for developing de novo autoimmune hepatitis associated with anti-glutathione S-transferase T1 antibodies after liver transplantation.

De novo autoimmune hepatitis (de novo AIH) is a rare form of graft dysfunction that develops after liver transplantation (LT) in patients transplanted for conditions other than autoimmune disorders. Although characterized by biochemical, serological, and histological features of AIH, de novo AIH is sometimes associated with atypical serum autoantibodies, many of which are directed against glutathione S-transferase T1 (anti-GSTT1). GSTT1 donor/recipient genotype mismatch has been suggested as a necessary condition for the appearance of autoantibodies and de novo AIH. However, clinically evident disease is not observed in all patients with anti-GSTT1 antibodies. We examined the incidence of de novo AIH and its conditioning (risk) factors in patients with anti-GSTT1 antibodies. Anti-GSTT1 autoantibodies were detected in 29 of 419 [6.9%; 95% confidence interval (CI), 4.9-9.8] consecutive adult LT recipients with donor/recipient GSTT1 mismatch. Twenty of 27 assessable patients (74%) developed de novo AIH after a median follow-up of 26 months (95% CI, 19.2-32.8). The probability of de novo AIH was 11%, 44%, and 60% 12, 24, and 36 months after LT, respectively. No relationship emerged between de novo AIH and recipient gender, donor and recipient age, rejection episodes, immunosuppressive regime, allelic GSTT1 expression, human leukocyte antigen distribution, or cytomegalovirus infection. Multivariate analysis identified male donor [hazard ratio (HR), 3.3; 95% CI, 1.18-9.26; P = 0.018], nonalcoholic etiology (HR, 4.67; 95% CI, 1.64-13.3; P = 0.002), and high anti-GSTT1 titer (HR, 2.98; 95% CI, 1.04-8.57; P = 0.035) as independent predictors of de novo AIH. Most patients with anti-GSTT1 antibodies and donor/recipient GSTT1 mismatch developed clinically evident de novo AIH after LT. The risk of developing the disease was increased by male donor gender, nonalcoholic etiology of original liver disease, and a high anti-GSTT1 titer.

Functional assessment of perforin C2 domain mutations illustrates the critical role for calcium-dependent lipid binding in perforin cytotoxic function.

Perforin-mediated lymphocyte cytotoxicity is critical for pathogen elimination and immune homeostasis. Perforin disruption of target cell membranes is hypothesized to require binding of a calcium-dependent, lipid-inserting, C2 domain. In a family affected by hemophagocytic lymphohistiocytosis, a severe inflammatory disorder caused by perforin deficiency, we identified 2 amino acid substitutions in the perforin C2 domain: T435M, a previously identified mutant with disputed pathogenicity, and Y438C, a novel substitution. Using biophysical modeling, we predicted that the T435M substitution, but not Y438C, would interfere with calcium binding and thus cytotoxic function. The capacity for cytotoxic function was tested after expression of the variant perforins in rat basophilic leukemia cells and murine cytotoxic T lymphocytes. As predicted, cells transduced with perforin-T435M lacked cytotoxicity, but those expressing perforin-Y438C displayed intact cytotoxic function. Using novel antibody-capture and liposome-binding assays, we found that both mutant perforins were secreted; however, only nonmutated and Y438C-substituted perforins were capable of calcium-dependent lipid binding. In addition, we found that perforin-Y438C was capable of mediating cytotoxicity without apparent proteolytic maturation. This study clearly demonstrates the pathogenicity of the T435M mutation and illustrates, for the first time, the critical role of the human perforin C2 domain for calcium-dependent, cytotoxic function.

Antibodies against glutathione S-transferase T1 (GSTT1) in patients with GSTT1 null genotype as prognostic marker: long-term follow-up after liver transplantation.

An objective to improve the evolution of transplants is to identify risk biomarkers of morbidity and loss of allograft. In liver transplant (LTX) recipients, an association has been demonstrated between the presence of mismatch for glutathione S-transferase T1 (GSTT1) and the development of de novo immune hepatitis (IH). In 419 LTX patients we analyzed, for a period of 1 to 14 years, the development of "atypical" autoantibodies directed against GSTT1 and their relationship with the mismatch for GSTT1 genotype and with the risk for developing de novo IH. A total of 6.9% LTX recipients had "atypical" autoantibodies and 24 showed mismatch (recipient/donor) for GSTT1 genotype. From this last group, up to 70% developed de novo IH and graft dysfunction after LTX (95% confidence interval: 17.4-37.5 months). In LTX recipients with a GSTT1 null genotype, the evaluation of "atypical" autoantibodies is useful for monitoring the development of de novo IH.

[Prevalence of C77G polymorphism in exon 4 of the CD45 gene in the Spanish population]. / Prevalencia del polimorfismo C77G en el exón 4 del gen CD45 en la población española.

BACKGROUND AND OBJECTIVE: A mutation (C77G) in exon 4 of the CD45 gene is the most common cause of CD45 abnormal splicing in European populations, which has been associated with an increased susceptibility to human immunodeficiency virus infection. We aimed to analyze the C77G frequency in the Spanish population. PATIENTS AND METHOD: 517 healthy donors. CD45RA and RO expression was determined in circulating T lymphocytes by flow cytometry. CD45 exon 4 sequencing was carried out in individuals with an abnormal coexpression of CD45 isoforms. RESULTS: 6/517 individuals presented CD45RA persistence on memory T cells; all of them were heterozygous for C77G mutation. The resulting allelic frequency was 0,58% (95% confidence interval, 0.23-1.32). CONCLUSIONS: C77G is present in the Spanish population. Further studies to elucidate its clinical significance are needed.

Prevalencia del polimorfismo C77G en el exón 4 del gen CD45 en la población española / Prevalence of C77G polymorphism in exon 4 of the CD45 gene in the Spanish population

Fundamento y objetivo: El cambio C77G en el exón 4 del gen CD45 produce un splicing anormal frecuente en poblaciones sanas europeas y relacionado con la infección por el virus de la inmunodeficiencia humana. El objetivo de este trabajo es analizar la frecuencia de C77G en la población española. Pacientes y método: Se incluyeron 517 muestras de sangre anticoagulada con ácido etilendiaminotetraacético procedentes de donantes sanos, en las que se determinó la expresión de CD45RA y CD45RO sobre linfocitos T circulantes mediante citometría de flujo. Se realizó asimismo la secuenciación del exón 4 de CD45 en las muestras con coexpresión anormal de ambas isoformas de CD45. Resultados: En 6 de 517 individuos se detectó persistencia de la expresión de CD45RA en los linfocitos T memoria; todos ellos eran heterocigotos para C77G. La frecuencia alélica es del 0,58% (intervalo de confianza del 95%, 0,23-1,32). Conclusiones: La mutación C77G está presente en la población sana española. Establecer su significado clínico requiere estudios con grupos de pacientes

Background and objective: A mutation (C77G) in exon 4 of the CD45 gene is the most common cause of CD45 abnormal splicing in European populations, which has been associated with an increased susceptibility to human immunodeficiency virus infection. We aimed to analyze the C77G frequency in the Spanish population. Patients and method: 517 healthy donors. CD45RA and RO expression was determined in circulating T lymphocytes by flow cytometry. CD45 exon 4 sequencing was carried out in individuals with an abnormal coexpression of CD45 isoforms. Results: 6/517 individuals presented CD45RA persistence on memory T cells; all of them were heterozygous for C77G mutation. The resulting allelic frequency was 0,58% (95% confidence interval, 0.23-1.32). Conclusions: C77G is present in the Spanish population. Further studies to elucidate its clinical significance are needed

The potential role of the HIV-1 immunogen (Remune) as a therapeutic vaccine in the treatment of HIV infection.

Immune-based therapies, such as therapeutic vaccination, that might preserve, restore, enhance and induce new HIV-specific immunologic responses are currently being explored. HIV-specific immunotherapy with Remune (The Immune Response Corp.) offers the opportunity to boost immune responses against HIV-1. The clinical trial program in a wide range of subjects has established the efficacy of Remune in stimulating an appropriate immune response in HIV-positive individuals. Furthermore, a recent unblinded study conducted in Europe has documented a significant effect of Remune on viral load. Evidence regarding clinical end points is more difficult to collect. The same studies have revealed no serious safety issues in a total of more than 2000 Remune-treated patients. It is therefore reasonable to suggest that the risk-benefit ratio of Remune could be positive.