Bárbara Leal

The Protective Role of HLA-DRB1∗13 in Autoimmune Diseases

Autoimmune diseases (AIDs) are characterized by a multifactorial aetiology and a complex genetic background, with the MHC region playing a major role. We genotyped for HLA-DRB1 locus 1228 patients with AIDs-213 with Systemic Lupus Erythematosus (SLE), 166 with Psoriasis or Psoriatic Arthritis (Ps + PsA), 153 with Rheumatoid Arthritis (RA), 67 with Systemic Sclerosis (SSc), 536 with Multiple Sclerosis (MS), and 93 with Myasthenia Gravis (MG) and 282 unrelated controls. We confirmed previously established associations of HLA-DRB1∗15 (OR = 2.17) and HLA-DRB1∗03 (OR = 1.81) alleles with MS, HLA-DRB1∗03 with SLE (OR = 2.49), HLA-DRB1∗01 (OR = 1.79) and HLA-DRB1∗04 (OR = 2.81) with RA, HLA-DRB1∗07 with Ps + PsA (OR = 1.79), HLA-DRB1∗01 (OR = 2.28) and HLA-DRB1∗08 (OR = 3.01) with SSc, and HLA-DRB1∗03 with MG (OR = 2.98). We further observed a consistent negative association of HLA-DRB1∗13 allele with SLE, Ps + PsA, RA, and SSc (18.3%, 19.3%, 16.3%, and 11.9%, resp., versus 29.8% in controls). HLA-DRB1∗13 frequency in the AIDs group was 20.0% (OR = 0.58). Although different alleles were associated with particular AIDs, the same allele, HLA-DRB1∗13, was underrepresented in all of the six diseases analysed. This observation suggests that this allele may confer protection for AIDs, particularly for systemic and rheumatic disease. The protective effect of HLA-DRB1∗13 could be explained by a more proficient antigen presentation by these molecules, favouring efficient clonal deletion during thymic selection.

Epilepsy, hippocampal sclerosis and febrile seizures linked by common genetic variation around SCN1A

Epilepsy comprises several syndromes, amongst the most common being mesial temporal lobe epilepsy with hippocampal sclerosis. Seizures in mesial temporal lobe epilepsy with hippocampal sclerosis are typically drug-resistant, and mesial temporal lobe epilepsy with hippocampal sclerosis is frequently associated with important co-morbidities, mandating the search for better understanding and treatment. The cause of mesial temporal lobe epilepsy with hippocampal sclerosis is unknown, but there is an association with childhood febrile seizures. Several rarer epilepsies featuring febrile seizures are caused by mutations in SCN1A, which encodes a brain-expressed sodium channel subunit targeted by many anti-epileptic drugs. We undertook a genome-wide association study in 1018 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 7552 control subjects, with validation in an independent sample set comprising 959 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 3591 control subjects. To dissect out variants related to a history of febrile seizures, we tested cases with mesial temporal lobe epilepsy with hippocampal sclerosis with (overall n = 757) and without (overall n = 803) a history of febrile seizures. Meta-analysis revealed a genome-wide significant association for mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures at the sodium channel gene cluster on chromosome 2q24.3 [rs7587026, within an intron of the SCN1A gene, P = 3.36 × 10−9, odds ratio (A) = 1.42, 95% confidence interval: 1.26–1.59]. In a cohort of 172 individuals with febrile seizures, who did not develop epilepsy during prospective follow-up to age 13 years, and 6456 controls, no association was found for rs7587026 and febrile seizures. These findings suggest SCN1A involvement in a common epilepsy syndrome, give new direction to biological understanding of mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures, and open avenues for investigation of prognostic factors and possible prevention of epilepsy in some children with febrile seizures.

Association between vitamin D receptor (VDR) gene polymorphisms and systemic lupus erythematosus in Portuguese patients

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease of unknown origin, in which both genetic and environmental factors are involved. One such environmental factor is vitamin D, a vital hormone that plays a specific function in the immune system homeostasis, acting through a nuclear receptor (VDR) expressed in all immune cells. Several polymorphisms of the gene that encodes this receptor have been described. Though inconsistently, these polymorphisms have been associated with clinical manifestations and SLE development. The aim of this study was to determine the possible association between VDR gene polymorphisms (BsmI, ApaI, TaqI e FokI) and SLE susceptibility and severity, in a cohort of lupus patients from the north of Portugal. A total of 170 patients (F = 155, M = 15; age = 45 ± 13.4 years) with SLE (diagnosed according the American College of Rheumatology criteria) with at least five years of disease evolution and followed in the Autoimmune Disease Clinical Immunology Unit of Centro Hospitalar do Porto were studied. Patients and 192 ethnicity-matched controls were genotyped for BsmI (rs1544410), ApaI (rs7975232), TaqI (rs731236) and FokI (rs2228570) polymorphisms by TaqMan allelic discrimination assay. Disease severity was assessed by SLICC damage score, number of affected organs, number of severe flares and pharmacological history. SLE patients with the CT genotype of FokI polymorphism have a higher SLICC value (p = 0.031). The same result was observed for the group of patients with the TT genotype of TaqI polymorphism (p = 0.046). No differences were observed in VDR genotype between patients and controls. Also, we observed that the other clinical features analysed were not influenced by VDR polymorphisms. Our study confirms a possible role of VDR gene polymorphisms in SLE. A positive association was found between VDR polymorphisms and SLE severity (chronic damage). The presence of CT genotype of FokI and TT genotype of TaqI seems to confer a worse prognosis and may constitute a risk factor for higher long-term cumulative damage in SLE patients.

HLA in Portuguese systemic lupus erythematosus patients and their relation to clinical features.

Systemic lupus erythematosus (SLE) is a clinically heterogeneous disease translating the different genetic and environmental factors involved. Polymorphisms at several loci, including the major histocompatibility complex (MHC), have been associated worldwide with SLE, although inconsistencies exist among these studies mainly due to genetic heterogeneity between populations and sample characteristics. The aim of the present study was to investigate in Portuguese SLE the association of HLA‐DRB1 alleles with clinical patterns of the disease and severity. Two hundred eighteen Portuguese patients with SLE—42% of whom had kidney involvement—were studied for HLA‐DRB1. Clinical and laboratory manifestations were correlated with HLA allele frequencies. HLA‐DRB1 * 03 allele frequency was significantly higher in SLE patients—as a whole and as either with or without renal involvement—compared to controls, while HLA‐DRB1 * 09 and DRB1 * 13 allele frequencies were decreased. Regarding the relationship with the presence or absence of specific clinical manifestations, it was only found that HLA‐DRB1 * 08 allele frequency was increased in patients with neurological involvement. No association with the presence or absence of anti‐dsDNA, anti‐sm or antiphospholipid antibodies, or antiphospholipid syndrome, was observed. These results were reproducible when analysis was repeated only with patients with more than 5 years of evolution. As in other populations HLA‐DRB1 * 03 is a susceptibility allele in Portuguese SLE patients, while HLA‐DRB1 * 09 and DRB1 * 13 alleles may be protective alleles, not only for the disease, but for the development of nephritis. No correlations with the different clinical manifestations were found, except with the neurological system.

The role of KIR2DS1 in multiple sclerosis - KIR in Portuguese MS patients

Killer Immunoglobulin-like Receptor (KIR) genes may influence both resistance and susceptibility to different autoimmune diseases, but their role in the pathogenesis of Multiple Sclerosis (MS) is still unclear. We investigated the influence of KIR genes on MS susceptibility in 447 MS Portuguese patients, and also whether genetic interactions between specific KIR genes and their HLA class I ligands could contribute to the pathogenesis of MS. We observed a negative association between the activating KIR2DS1 gene and MS (adjusted OR=0.450, p=0.030) independently from the presence of HLA-DRB1*15 allele. The activating KIR2DS1 receptor seems to confer protection against MS most probably through modulation of autoreactive T cells by Natural Killer cells.

CCR5‐Delta32: implications in SLE development

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease with strong genetic and environmental components. Previous studies have shown increased levels of several chemokines in active SLE. C‐C chemokine receptor type 5 (CCR5) is involved in the recruitment of inflammatory cells into tissues, and mechanisms modulating CCR5 expression and function may interfere in SLE development, influencing the clinical course of the disease. The aim of this study was to evaluate the possible association between the CCR5∆32 base‐pair deletion polymorphism and SLE disease in a group of Portuguese patients. A total of 219 patients with SLE and 205 healthy individuals were studied. The frequency of CCR5/∆32 heterozygotes was lower in patients with SLE than in controls (8% vs. 15% OR = 0.5162; P = 0.0319), suggesting a protective association between CCR5∆32 allele and SLE. These results highlight the protective role of Th1 cells that express CCR5 in SLE pathogenesis.

Photosensitivity and epilepsy: Current concepts and perspectives—A narrative review

The authors review the influence of photic stimuli on the generation of epileptic seizures, addressing the first descriptions of the phenomenon and its subsequent exploration. Initially defined in the 1950s, links between intermittent photic stimulation (IPS) and seizures were well understood by the 1970. Since then the increasing exposure to photic stimuli associated with modern life (for instance through TVs, patterns, computer games and electronic instruments with flickering displays) has led to an increased interest in this issue. Diverse stimulation procedures have been described and difference in the effects of stimulation frequencies and types, colour and lighting have been recognised. Approximately 5% of patients with epilepsy have photosensitive epilepsy (PSE). PSE is commoner in younger individuals, more frequent in women, often time-limited, generally easy to treat and closely related to generalised epilepsies, especially Juvenile Myoclonic Epilepsy (JME). Structural and functional studies of PSE indicate abnormalities beyond the frontal lobes and evidence for the role of the visual cortex in human PSE. A reduction in connectivity between prefrontal and frontopolar regions and increased connectivity between occipital cortex and the supplementary motor area may be the basis for triggering motor seizures in JME. Due to the changes observed in such areas, it is hypothesised that photoparoxysmal responses (PPR) could be a final expression of pathogenic phenomena in the striato-thalamocortical system, and possibly a core feature of JME as system epilepsy. The familial transmission of epileptiform responses to IPS is well-recognised, but no clear relation between PSE and specific genes has emerged. Although the influence of ethnic factors on PSE has been widely studied, clear conclusions are still lacking. Pharmacological therapeutic approaches are beyond the scope of this review although preventive measures allowing patients to avoid PS seizure initiation and/or generalisation are discussed. Given the gender/age group most commonly affected by PSE, the risks and benefits of drug treatment need to be carefully weighed up.

Immunogenetic Predisposing Factors for Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis

ABSTRACT Purpose: Neuroinflammation appears as an important epileptogenic mechanism. Experimental and clinical studies have demonstrated an upregulation of pro-inflammatory cytokines such as IL-1β and TNF-α, in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). Expression of these cytokines can be modulated by polymorphisms such as rs16944 and rs1800629, respectively, both of which have been associated with febrile seizures (FS) and MTLE-HS development. The human leukocyte antigen (HLA) system has also been implicated in diverse epileptic entities, suggesting a variable role of this system in epilepsy. Our aim was to analyse the association between immunogenetic factors and MTLE-HS development. For that rs16944 (-511 T>C, IL-1β), rs1800629 (-308 G>A, TNF-α) polymorphisms and HLA-DRB1 locus were genotyped in a Portuguese Population. Methods: We studied 196 MTLE-HS patients (108 females, 88 males, 44.7 ± 12.0 years, age of onset = 13.6 ± 10.3 years, 104 with FS antecedents) and 282 healthy controls in a case–control study. Results: The frequency of rs16944 TT genotype was higher in MTLE-HS patients compared to controls (14.9% in MTLE-HS vs. 7.7% in controls, p = 0.021, OR [95% CI] = 2.20 [1.13–4.30]). This association was independent of FS antecedents. No association was observed between rs1800629 genotypes or HLA-DRB1 alleles and MTLE-HS susceptibility. Also, no correlation was observed between the studied polymorphisms and disease age of onset. Conclusion: The rs16944 TT genotype is associated with MTLE-HS development what may be explained by the higher IL-1β levels produced by this genotype. High IL-1β levels may have neurotoxic effects or imbalance neurotransmission leading to seizures.

Brain expression of inflammatory mediators in Mesial Temporal Lobe Epilepsy patients

Neuroinflammation may be central in epileptogenesis. In this study we analysed inflammatory reaction markers in brain tissue of Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) patients. TLR4, IL-1β and IL-10 gene expression as well as the presence of activated HLA-DR+ microglia was evaluated in 23 patients and 10 cadaveric controls. Inflammation characterized by the presence of HLA-DR+ microglia and TLR4, IL-1β overexpression was evident in hippocampus and anterior temporal cortex of MTLE-HS patients. Anti-inflammatory IL-10 was also overexpressed in MTLE-HS patients. Our results show that hippocampal neuroinflammation extends beyond lesional limits, as far as the anterior temporal cortex.

The vitamin D receptor gene FokI polymorphism and Multiple Sclerosis in a Northern Portuguese population

BACKGROUND The cause of Multiple Sclerosis (MS) remains poorly understood, but it is widely believed to be an autoimmune disease occurring in genetically susceptible individuals after exposure to as-yet undefined environmental factors. One of these environmental factors is vitamin D, a well-known immune modulator. The biologically active form of vitamin D, 1,25-dihydroxyvitamin D3, has been shown to exert its immune modulatory properties through its nuclear receptor (VDR) namely by inhibiting the proliferation of Th cells. The purpose of this study was to evaluate the influence of FokI VDR polymorphism in MS development and progression. METHODS A group of 533 unrelated Portuguese patients with a definitive diagnosis of MS and 446 ethnically matched healthy controls were included in the study. FokI was genotyped using a PCR-based TaqMan Genotyping Assay and serum 25-hydroxyvitamin D [25(OH)D] was also assessed. RESULTS A statistically significant higher frequency of the ff genotype was observed in MS patients (15.6% vs. 10.1%, p=0.012, OR (95% CI)=1.687(1.120-2.541)). No differences were observed in the frequencies of the FokI polymorphism according to disease course or with progression of disability. None of the genotypes was significantly associated with 25(OH)D serum levels. CONCLUSIONS An association between FokI ff genotype and MS susceptibility was found, but not with disease form or progression. Additional clinical and experimental studies should take the FokI VDR polymorphism into account, and further clarify the role of vitamin D, its metabolites and its receptor in MS.