HLA‐G: Function, polymorphisms and pathology Arnaiz‐Villena, Antonio; Juarez, Ignacio; Suarez‐Trujillo, Fabio ...
International journal of immunogenetics,
April 2021, 2021-Apr, 2021-04-00, 20210401, Letnik:
48, Številka:
2
Journal Article
Recenzirano
Odprti dostop
HLA‐G immune modulatory genes and molecules are presently being studied by a widespread number of research groups. In the present study, we do not aim to be exhaustive since the number of manuscripts ...published every year is overwhelming. Instead, our aim is pointing out facts about HLA‐G function, polymorphism and pathology that have been confirmed by several different researchers, together with exposing aspects that may have been overlooked or not sufficiently remarked in this productive field of study. On the other hand, we question whether performing mainly studies on HLA‐G and disease associations is going to give a clear answer in the future, since 40 years of study of classical HLA molecules association with disease has still given no definite answer on this issue.
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 Arnaiz‐Villena, Antonio; Suárez‐Trujillo, Fabio; Palacio‐Gruber, José ...
International journal of immunogenetics,
October 2021, 2021-Oct, 2021-10-00, 20211001, Letnik:
48, Številka:
5
Journal Article
Recenzirano
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.
HLA-G is a non-classical class I HLA molecule that induces tolerance by acting on receptors of both innate and adaptive immune cells. When overexpressed in tumors, limits surveillance by the immune ...system. The
gene shows several polymorphisms involved in mRNA and protein levels. We decided to study the implication of two polymorphisms (rs371194629; 14bp INS/DEL and rs1063320; +3142 C/G) in paired tissue samples (tumoral and non-tumoral) from 107 Spanish patients with gastric adenocarcinoma and 58 healthy control individuals, to assess the possible association of the
gene with gastric adenocarcinoma susceptibility, disease progression and survival. The presence of somatic mutations involving these polymorphisms was also analyzed. The frequency of the 14bp DEL allele was increased in patients (70.0%) compared to controls (57.0%, p=0.025). In addition, the haplotype formed by the combination of the 14bp DEL/+3142 C variants is also increased in patients (54.1%
44.4%, p=0.034, OR=1.74 CI95% 1.05-2.89). Kaplan-Meier analysis revealed that 14bp DEL/DEL patients showed lower 5-year life-expectancy than INS/DEL or INS/INS (p=0.041). Adjusting for TNM staging (Cox regression analysis) disclosed a significant difference in death risk (p=0.03) with an expected hazard 2.6 times higher. Finally, no somatic mutations were found when comparing these polymorphisms in tumoral
non-tumoral tissues, which indicates that this is a preexisting condition in patients and not a
, tumor-restricted, event. In conclusion, the variants predominant in patients were those increasing HLA-G mRNA stability and HLA-G expression, clearly involving this molecule in gastric adenocarcinoma susceptibility, disease progression and survival and making it a potential target for immunotherapeutic approaches.
HLA and disease studies by using single allele statistics have been fruitless during the last 40 years for explaining association pathogenesis of the associated diseases.Other approaches are ...necessary to untangle this puzzle. We aim to revisit complement alleleism in humans and primates for both studying MHC and disease association to complotypes and extended MHC haplotypes in order to also explain the positive directional selection of maintaining immune response genes (complement, MHC adaptive and MHC non-specific genes) that keeps these three type of genes together in a short chromosome stretch (MHC) for million years. These genes may be linked to conjointly avoid microbes attack and autoimmunity. In the present paper, it is obtained a new Bf chimpanzee allele, provisionaly named Patr-Bf*A:01,that differs from other Bf alleles by having CTG at eleventh codon of exon 2 in order to start the newly suggested methodology and explain functional and evolutionary MHC obscure aspects. Exons 1 to 6 of Ba fragment of Bf gene were obtained from chimpanzee. This new chimpanzee Factor B allele (Patr-Bf*A:01) is to be identical to a infrequent human Bf allele (SNP rs641153); it stresses the strong evolutive pressure upon certain alleles that are trans specific. It also may apply to MHC extended haplotipes which may conjointly act to start an adequate immune response. It is the first time that a complement MHC class III allele is described to undergo trans species evolution,in contrast to class I and class II alleles which had already been reported . Allelism of complement factors are again proposed for studying MHC complement genes, complotypes, and extended MHC haplotypes which may be more informative that single MHC marker studies.
Abstract
The contribution of migrated people from once green Sahara (about 10,000–6000 years
bc
) towards Mediterranean area had probably a double effect: both genetic and cultural connections have ...been described between Western Europe and North Africa. Sudanese populations from different ethnicities have been studied for HLA-A, -B, -DRB1 and -DQB1 antigens by a standard microlymphotoxicity method. Results found show that Nubians are genetically related with African Sub-Saharan populations and distant from other Sudanese tribes, who are closer to Mediterranean populations than to Sub-Saharan ones. This is concordant with other authors and meta-analysis data. Our present work is, to our knowledge, the first and only one HLA research that studies Sudanese people according to different Sudan ethnic groups: samples were collected before Sudan partition between North and South. A prehistoric genetic and peoples exchange between Africa and the Mediterranean basin may be observed and is supported with the results obtained in this Sudanese HLA study. However, demic diffusion model of agriculture and other anthropological traits from Middle East to West Europe/Maghreb do not exist: a more detailed Sahel and North African countries ancient and recent admixture studies are also being carried out which may clearer explain pastoralists/agriculture innovations origins in Eurafrican Mediterranean and Atlantic façade.
HLA study in Iranian desert Yazd province inhabitants Suarez-Trujillo, Fabio; Amirzargar, Ali; Hadinedoushan, Hossein ...
Human immunology,
May-July 2023, 2023 May-Jul, 2023-05-00, 20230501, Letnik:
84, Številka:
5-7
Journal Article
Recenzirano
Odprti dostop
Yazd City (1,200,000 inhabitants) is placed in the middle of its Iran desert province and it was constructed on a oasis in ancient times.However,it was a central point on the Silk Road and merchants ...from both Asia and Mediterranean/European areas crossed through Yazd City.We have studied HLA-A,-B,-DRB1 and DQB1 alleles in Yazd population.Analysys of nine most frequent extended class I and class II haplotypes shows that four of them are specific of this population.The other six haplotypes are also found in Asian and Mediterranean populations in significant frequency. This supports that the nowadays relatively isolated in desert Yazd area also contains people that may bear HLA genes probably originated because of long lasting merchants route between Europe and Asia through the European/Asian Silk Road in addition to other HLA genes close to other Iranian populations, including Kurds.
HLA studies in Crete show that this population is related to North Africans and also Iberians. This may be a reflection of a common prehistoric first Europeans relationships with North Africans and ...drying Saharan emigration after 10,000 years BC; it may be specifically represented by a primitive and early cult to the bull in both Cretan (Minoan) and Iberian populations. In the present study, unrelated Cretans representing different Island parts have been studied for class II HLA-DRB1 and –DQB1 alleles. The most frequent ones were HLA-DRB1*11:01 and HLA-DRB1*07:01 and HLA-DQB1*03:01 and DQB1*05:01. Also, the Cretan HLA class II haplotype HLA-DBR1*11:01-DQB1*03:01 had the highest frequency and is also common to other Mediterraneans, including Iberians. In addition, DRB1*07:01-DQB1*02:01 and HLA-DRB1*04:02-DQB1*03:02 Cretan haplotypes are shared with North Africans (the latter with Algerians, Tunisians and Moroccans). In summary, Crete was one of the first European classic cultures (Minoan) which was probably an early link, like Iberia, between North Africa /Sahara and Europe,also supported by genetic results.
HLA and disease studies by using single allele statistics have been fruitless during the last 40 years for explaining association pathogenesis of the associated diseases.Other approaches are ...necessary to untangle this puzzle. We aim to revisit complement alleleism in humans and primates for both studying MHC and disease association to complotypes and extended MHC haplotypes in order to also explain the positive directional selection of maintaining immune response genes (complement, MHC adaptive and MHC non-specific genes) that keeps these three type of genes together in a short chromosome stretch (MHC) for million years. These genes may be linked to conjointly avoid microbes attack and autoimmunity. In the present paper, it is obtained a new Bf chimpanzee allele, provisionaly named Patr-Bf*A:01,that differs from other Bf alleles by having CTG at eleventh codon of exon 2 in order to start the newly suggested methodology and explain functional and evolutionary MHC obscure aspects. Exons 1 to 6 of Ba fragment of Bf gene were obtained from chimpanzee. This new chimpanzee Factor B allele (Patr-Bf*A:01) is to be identical to a infrequent human Bf allele (SNP rs641153); it stresses the strong evolutive pressure upon certain alleles that are trans specific. It also may apply to MHC extended haplotipes which may conjointly act to start an adequate immune response. It is the first time that a complement MHC class III allele is described to undergo trans species evolution,in contrast to class I and class II alleles which had already been reported . Allelism of complement factors are again proposed for studying MHC complement genes, complotypes, and extended MHC haplotypes which may be more informative that single MHC marker studies.
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.
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