HLA determinants of susceptibility to multiple sclerosis in an Arabian Gulf population

Major histocompatibility complex (MHC) associations with diseases in ethnic groups of the Arabian Peninsula

Since the discovery of human leukocyte antigens (HLAs), the function of major histocompatibility complex (MHC) gene families in a wide range of diseases have been the subject of research for decades. In particular, the associations of autoimmune disorders to allelic variants and candidate genes encoding the MHC are well documented. However, despite decades of research, the knowledge of MHC associations with human disease susceptibility have been predominantly studied in European origin, with limited understanding in different populations and ethnic groups. This is particularly evident in countries and ethnic populations of the Arabian Peninsula. Human MHC haplotypes, and its association with diseases, of the variable ethnic groups of this region are poorly studied. This review compiled published manuscripts that have reported a list of autoimmune diseases (insulin-dependent diabetes mellitus, systemic lupus erythematosus, myasthenia gravis, rheumatoid arthritis, psoriasis vulgaris, and multiple sclerosis) associated with MHC class I and class II in the populations of the Arabian Peninsula, specifically Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, the United Arab Emirates, and Yemen. Data available was compared with other three ethnic groups, namely Caucasians, Asians, and Africans. The limited data available in the public domain on the association between MHC gene and autoimmune diseases highlight the challenges in the Middle Eastern region.

Replication analysis of variants associated with multiple sclerosis risk

Multiple Sclerosis (MS) is a complex chronic neurodegenerative disorder resulting from an autoimmune reaction against myelin. So far, many genetic variants have been reported to associate with MS risk however their association is inconsistent across different populations. Here we investigated the association of the most consistently reported genetic MS risk variants in the Kuwaiti MS population in a case-control study designs. Of the 94 reported MS risk variants four variants showed MS risk association in Arabs exome analysis (EVI5 rs11808092 p = 0.0002; TNFRSF1A rs1800693 p = 0.00003; MTHFR rs1801131 p = 0.038; and CD58 rs1414273 p = 0.00007). Replication analysis in Kuwaiti MS cases and healthy controls confirmed EVI5 rs11808092A (OR: 1.6, 95%CI: 1.19–2.16, p = 0.002) and MTHFR rs1801131G (OR: 1.79, 95%CI: 1.3–2.36, p = 0.001) as MS risk genetic factors, while TNFRSF1A rs1800693C had a marginal MS risk association (OR: 1.36, 95%CI: 1.04–1.78, p = 0.025) in the Kuwaiti population. CD58 rs1414273 did not sustain risk association (p = 0.37). In conclusion, EVI5 rs11808092A, TNFRSF1A rs1800693C and MTHFR rs1801131G are MS risk factors in the Kuwaiti population. Further investigations into their roles in MS pathogenesis and progression are merited.

Multiple sclerosis and human leukocyte antigen genotypes: Focus on the Middle East and North Africa region

Recent reports have demonstrated that the prevalence of multiple sclerosis (MS) is increasing in the Middle East and North Africa region. There is also emerging evidence regarding the genetic components of MS risk. This review provides an overview of the role of genetic factors in MS susceptibility by examining human leukocyte antigen loci in patients within the Middle East and North Africa region. Most of the genetic studies conducted in the Middle East and North Africa region have been based on case–control designs, which cannot confirm direct causality of genetic variants on MS susceptibility. Moreover, there are very limited and inconsistent studies on human leukocyte antigen class I and II (DQA and DQB) in MS patients of the Middle East and North Africa region. To identify common risk haplotypes in the Middle East and North Africa region or its sub-populations, further longitudinal studies will be required.

Association of infections with multiple sclerosis in Gulf Cooperation Council countries: a review

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system, causing inflammation, demyelination, and neurodegeneration. Infection can play a role in its etiology. Herein, a review is presented of studies that have reported an association between infection and MS risk in countries of the Arabian Gulf region. Searches of the PubMed, Google Scholar, and Science Direct databases were carried out using various search terms, and relevant studies published through January 2019 on the epidemiology of MS in Gulf Cooperation Council countries identified. MS has been found to be associated with measles in Saudi Arabia and Epstein–Barr virus in Kuwait whereas no association has been identified between risk of MS and varicella-zoster virus, mumps, or human herpesvirus-6. However, few epidemiological studies on this topic have been conducted in countries of the Gulf region. Longitudinal and serological studies to establish robust evidence between infection and risk of MS are highly recommended, and a regional MS registry is needed.

Anti-Myelin Oligodendrocyte Glycoprotein and Human Leukocyte Antigens as Markers in Pediatric and Adolescent Multiple Sclerosis: on Diagnosis, Clinical Phenotypes, and Therapeutic Responses

Early-onset (pediatric and adolescent) multiple sclerosis (MS) is a well-established demyelinating disease that accounts for approximately 3-5% of all MS cases. Thus, identifying potential biomarkers that can reflect the pathogenic mechanisms, disease course and prognosis, and therapeutic response in such patients is of paramount importance. Myelin oligodendrocyte glycoprotein (MOG) has been regarded as a putative autoantigen and autoantibody target in patients with demyelinating diseases for almost three decades. However, recent studies have suggested that antibodies against MOG represent a distinct clinical entity of dominantly humoral profile, with a range of clinical phenotypes closely related to the age of onset, specific patterns of disease course, and responses to treatment. Furthermore, the major histocompatibility complex (MHC)—which has been regarded as the “gold standard” for attributing genetic burden in adult MS since the early 1970s—has also emerged as the primary genetic locus in early-onset MS, particularly with regard to the human leukocyte antigen (HLA) alleles DRB1⁎1501 and DRB1⁎0401. Recent studies have investigated the potential interactions among HLA, MOG, and environmental factors, demonstrating that early-onset MS is characterized by genetic, immunogenetic, immunological, and familial trait correlations. In this paper, we review recent evidence regarding HLA-genotyping and MOG antibodies—the two most important candidate biomarkers for early-onset MS—as well as their potential application in the diagnosis and treatment of MS.

Distinct HLA class I and II genotypes and haplotypes are associated with multiple sclerosis in Bahrain

Multiple sclerosis (MS) has become prevalent in the Arabian Gulf area with high incidence in Bahrain due to environmental influences and genetic susceptibilities, but there is a lack of study into human leukocyte antigen (HLA) types in patients with MS in Bahrain. The present study aimed to study the HLA types expressed in MS patients compared with in control subjects. Blood samples from 50 Bahraini patients with MS and 50 Bahraini control subjects' were subjected to HLA tissue typing by polymerase chain reaction using sequence-specific primers. In comparison with those in control subjects, the allele frequencies of HLA class-I antigens A2, A9, A19, B5, B35 and B40 were higher in MS patients. For class II antigens, the allele frequencies of DR3, DR4 and DR16 were higher in MS patients. The allele frequency of DR15 was lower in MS patients than in control subjects but the difference was not statistically significant (P=0.138). The higher prevalence of the HLA-ABDR allele was common among the female patients with MS, in relapse remission stage, in cases with higher expanded disability status scale scores and with disease duration between 4 and 9 years. Haplotype HLA-A2-B40-DR2 exhibited significantly higher frequency in MS patients compared with in control subjects (P=0.03). In conclusion, the results indicated different alleles associated with MS compared with previous reviews. The present study supports the importance of identifying genetic susceptibilities and targets for therapies in specific populations and individuals, to personalize disease management in terms of prediction, protective measures and treatment.

Autoimmune Subepidermal Bullous Diseases of the Skin and Mucosae: Clinical Features, Diagnosis, and Management

Autoimmune subepidermal blistering diseases of the skin and mucosae constitute a large group of sometimes devastating diseases, encompassing bullous pemphigoid, gestational pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, and anti-p200 pemphigoid. Their clinical presentation is polymorphic. These autoimmune blistering diseases are associated with autoantibodies that target distinct components of the basement membrane zone of stratified epithelia. These autoantigens represent structural proteins important for maintenance of dermo-epidermal integrity. Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease of the skin and mucosae. Although the disease typically presents with a generalized blistering eruption associated with itch, atypical variants with either localized bullous lesions or "non-bullous" presentations are observed in approximately 20% of patients. A peculiar form of BP typically associated with pregnancy is pemphigoid gestationis. In anti-p200 pemphigoid, patients present with tense blisters on erythematosus or normal skin resembling BP, with a predilection for acral surfaces. These patients have antibodies targeting the 200-kDa basement membrane protein. Epidermolysis bullosa is a rare autoimmune blistering disease associated with autoantibodies against type VII collagen that can have several phenotypes including a classical form mimicking dystrophic epidermolysis bullosa, an inflammatory presentation mimicking BP, or mucous membrane pemphigoid-like lesions. Mucous membrane pemphigoid (MMP) is the term agreed upon by international consensus for an autoimmune blistering disorder, which affects one or more mucous membrane and may involve the skin. The condition involves a number of different autoantigens in the basement membrane zone. It may result in severe complications from scarring, such as blindness and strictures. Diagnosis of these diseases relies on direct immunofluorescence microscopy studies and immunoserological assays. Management of affected patients is often challenging. We will here review the clinical and immunopathological features as well as the pathophysiology of this group of organ-specific autoimmune diseases. Finally, we will discuss the diagnostic approach and the principles of management in clinical practice.

HLA-DRB1 polymorphism and susceptibility to multiple sclerosis in the Middle East North Africa region: A systematic review and meta-analysis

This meta-analysis explores association of HLA-DRB1 alleles with MS risk in the Middle-east North Africa (MENA) countries. Divided into two groups of alleles (10 studies, 899 cases/1457 controls) and phenotypes (8 studies, 1,040 cases/1,256 controls), Odds ratios (ORs) of DRB1 distribution in MS subjects were assessed using Cochrane RevMan software. DRB1*15 demonstrated significant association with MS in both groups (OR=1.6 and OR=2.51, respectively). In phenotypes, DRB1*03 and DRB1*04 had predisposing role (OR=1.8 and OR=1.9), while DRB1*07 and DRB1*11 were protective (OR=0.56 and OR=0.67). Similar but non-significant trends were seen among alleles, which in sum coincides with a Caucasian-like pattern.

A multi-hit hypothesis of bullous pemphigoid and associated neurological disease: Is HLA-DQB1*03:01, a potential link between immune privileged antigen exposure and epitope spreading?

Bullous pemphigoid (BP) is the most common autoimmune blistering disease and is linked to IgG recognition of 2 hemidesmosomal antigens, that is, BP230 (BP antigen 1) and BP180 (BP antigen 2, collagen XVII). The association of BP with other systemic diseases, particularly neurocognitive diseases, provides a potential clue in the underlying pathogenesis of BP. The role of HLA-DQB1*03:01 binding to the immunogenic portion of BP180 provides a potential mechanism by which exposure to neuronal collagen BP180 may lead to cutaneous disease. In our proposed multi-hit hypothesis, patients with underlying neuronal disease are exposed to previously sequestered self-antigen, most importantly BP180. Patients with the HLA-DQB1*03:01 allele show an increased T-cell avidity to several epitopes of BP180, particularly the BP180-NC16a domain. Thus, they have a genetic susceptibility to developing BP upon exposure to the target antigen. In a patient with dysregulation of Th1/Th2 balance, anergy is lost and T-cells are subsequently primed resulting in the development of functional autoimmunity against the BP180-NC16a domain leading to clinically overt disease.

Modifying effects of HLA-DRB1 allele interactions on age at onset of multiple sclerosis in Western Australia

The contribution of genetic factors to the age at onset in multiple sclerosis is poorly understood. Our objective was to investigate the disease modifying effects of HLA-DRB1 alleles and allele interactions on age at onset of multiple sclerosis. High-resolution four-digit HLA-DRB1 genotyping was performed in a cohort of 461 multiple sclerosis patients from the Perth Demyelinating Diseases Database. Carriage of the HLA-DRB1*1501 risk allele was not significantly associated with age at onset but HLA-DRB1*0801 was associated with a later onset of the disease. The HLA-DRB1*0401 allele was associated with a reduced age at onset when combined with DRB1*1501 but may delay age at onset when combined with DRB1*0801. These findings indicate that epistatic interactions at the HLA-DRB1 locus have significant modifying effects on age at onset of multiple sclerosis and demonstrate the value of high-resolution genotyping in detecting such associations.

Multiple sclerosis patients show sexual dimorphism in cytokine responses to myelin antigens

Multiple sclerosis affects more women than men. The reasons for this are unknown. Previously, we have shown significant differences in women versus men in inflammatory cytokine responses to the major protein component of myelin, proteolipid protein (PLP), which is thought to be a target in MS patients. Here, using the ELISPOT assay, we examined sex differences in single-cell secretion of Th1 and Th2 cytokines from freshly isolated PBMC between relapsing remitting (RR) MS patients and healthy individuals. Cells were stimulated with MS-associated antigens including proteolipid protein (PLP), myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG), and non-disease related antigens. Our data show a sex bias in the cytokine responses to multiple MS-relevant myelin antigens: Women with MS show IFNgamma-skewed responses and men with MS show IL-5-skewed responses. These data extend our previous findings [Pelfrey, C.M., Cotleur, A.C., Lee, J.C., Rudick, R.A. 2002. Sex differences in cytokine responses to myelin peptides in multiple sclerosis. J. Neuroimmunol. 130, 211-223.]: (1) by demonstrating gender skewing in cytokine responses to an expanded myelin antigen repertoire, which includes MBP, MOG and PLP; (2) by showing TNFalpha and IL-10 do not display comparable gender skewing compared to IFNgamma and IL5; (3) by defining the patient population as early, untreated RRMS patients to avoid confounding factors, such as different disease stages/disability and immunomodulatory therapy; and (4) by showing HLA type does not appear to underlie the gender differences. These findings may explain increased susceptibility to MS in women and could contribute to the differences in disease severity between men and women.

Human leukocyte antigen (HLA) DR15 is associated with reduced incidence of acute GVHD in HLA-matched allogeneic transplantation but does not impact chronic GVHD incidence

The DR15 allele at the HLA DRB1 locus is a marker for immune-mediated bone marrow failure syndromes. We hypothesized that HLA DR15 plays a role in T-cell interactions with hematopoiesis and investigated the role of HLA DR15 on graft-versus-host disease (GVHD) and graft-versus-leukemia effects in HLA-matched allogeneic blood or marrow transplantation (BMT) performed for myeloid malignancies. We performed a retrospective analysis of 119 consecutive related and 48 consecutive unrelated allogeneic BMT for myeloid malignancies treated between 1991 and 2005 to investigate the influence of HLA DR15 on overall survival (OS), progression-free survival (PFS), and incidence of grades II to IV acute GVHD. HLA DR15 was determined by either molecular (n = 108) or serologic (n = 59) methods. The incidence of HLA DR15 was similar to the general white population (35/167 = 21%). There were no significant differences in transplantation characteristics between the HLA DR15–positive and –negative groups. There was no significant difference in chronic GVHD, OS, or PFS between the HLA DR15–positive versus–negative groups in any disease or donor relation subgroups. The HLA DR15–positive group experienced a significantly lower incidence of acute GVHD grades II to IV: 23% versus 42% (P = .041). These results suggest that HLA DR15 reduces the risk of acute GVHD.