HLA B44 is associated with decreased severity of autoimmune lymphoproliferative syndrome in patients with CD95 defects (ALPS type Ia)

The role of human leukocyte antigen in HTLV-1 infection and progression to ATLL and HAM/TSP: a systematic review and meta-analysis

BACKGROUND

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that leads to lifelong infection and multiple diseases, including HAM/TSP and ATLL. Despite extensive research, the exact pathophysiology of HTLV infection and its related diseases is enigmatic. In this study, we aimed to review and analyze the effect of different HLA alleles as protective or predisposing factors in HTLV-1 infection and its progression to related diseases.

METHOD

Three databases (PubMed, Web of Science, and Scopus) were searched for eligible studies. Twenty-five papers with 7279 participants were included in the quantitative analysis. The relevant data were extracted, and 198 meta-analyses were conducted on each reported HLA and population.

RESULTS

The results of our investigation suggest 3 HLAs with preventive effects against HTLV infection, including HLA-B*35, DRB1*09, and DRB1*16. Also, HLA-DQB1*05:01 might prevent HTLV progression to ATLL. In contrast, HLA-DRB1*13 is more prevalent in ATLL patients than HTLV carriers. Additionally, our results propound that carriers of HLA-A*28, B*54, C*07, DQB1*03:01, and DRB1*07:01 are at higher risk, and carriers of HLA-A*30, B*37, B*40, B*44, C*08, DQB1*06:02, and DRB1*15:01 are in lower risk of HTLV progression to HAM/TSP. We concluded that the mentioned HLA alleles are potential biomarkers of HTLV infection and its progression to related diseases.

Clinical Phenotype of HLA B*44 Patients in a Rheumatology Outpatient Clinic Favors Peripheral Arthropathies

Objective: The genetic background of HLA-B*27 in spondyloarthritis is known, and the search for another gene with similar role is ongoing. We wanted to investigate clinical presentations of HLA-B*44 patients in rheumatology practice. Methods: A cross-sectional retrospective study of 303 HLA-B*44 adult patients from the outpatient rheumatology clinic from 5/2018-5/2024. Clinical phenotype, confirmed or excluded rheumatic diagnosis, therapy used, and data on HLA A, B, and DR alleles inherited with B*44 were analyzed. Results: A female predominance of 2.79:1 was noted. A total of 150 [49.5%] patients were referred due to peripheral joint pain, 77 [25.4%] due to combined spine and peripheral joint pain or spine alone (57 [18.8%]). A total of 19 [6.3%] patients had no symptoms of the musculoskeletal system. Statistically significant peripheral joint affection was proved in females but not in males (p = 0.04). A total of 121 [40%] patients from B*44 group had established rheumatic disease, with the rest being excluded or under observation. The most common working diagnoses were polyarthritis (32 [10.5%]) and mono-oligoarthritis (14 [4.6%]). A second allele in addition to HLA B*44 showed a similar frequency to the general population. Patients with HLA B*44/44 and B*27/44 genotypes were at the most risk for having definitive rheumatic disease (>60%). Conventional synthetic disease-modifying anti-rheumatic drugs (DMARDs) were used in 38.6% of patients, non-steroidal anti-inflammatory drugs were used in 31.6% of patients, biologic DMARDs were used in 8.9% of patients, and corticosteroids were used in 7.3% of patients. Conclusions: The most common presentation in HLA-B*44 patients is peripheral joint affection. Most patients with HLA-B*27/44 and B*44/44 genotypes had definitive rheumatic disease. B*44 homozygosity or B*27/44 might be risk factors for arthritis development.

Autoimmune lymphoproliferative syndrome due to FAS mutations outside the signal-transducing death domain: molecular mechanisms and clinical penetrance

PURPOSE

Autoimmune lymphoproliferative syndrome is a disorder of lymphocyte apoptosis. Although FAS molecules bearing mutations in the signal-transducing intracellular death domain exhibit dominant-negative interference with FAS-mediated apoptosis, mechanisms for pathology of non-death domain FAS mutations causing autoimmune lymphoproliferative syndrome are poorly defined.

METHODS

RNA stability, protein expression, ligand binding, and ability to transmit apoptosis signals by anti-FAS antibody or FAS ligand were determined for a cohort of 39 patients with non-death domain autoimmune lymphoproliferative syndrome. Correlations between mutation type and disease penetrance were established in mutation-positive family members.

RESULTS

Frameshifts or transcriptional stop mutations before exon 7 resulted in messenger RNA haploinsufficiency, whereas an amino-terminal signal sequence mutation and certain intracellular truncations prevented cell surface localization of FAS. All resulted in decreased FAS localization, inability to bind FAS ligand, and reduced FAS ligand-induced apoptosis. Extracellular missense mutations and in-frame deletions expressed defective FAS protein, failed to bind FAS ligand, and exhibited dominant-negative interference with FAS-mediated apoptosis. Mutation-positive relatives with haploinsufficient or extracellular mutations had lower penetrance of autoimmune lymphoproliferative syndrome clinical phenotypes than did relatives with death domain mutations.

CONCLUSION

We have defined molecular mechanisms by which non-death domain FAS mutations result in reduced lymphocyte apoptosis, established a hierarchy of genotype-phenotype correlation among mutation-positive relatives of patients with autoimmune lymphoproliferative syndrome, and demonstrated that FAS haploinsufficiency can lead to autoimmune lymphoproliferative syndrome.

HLA B*44: protective effects in MS susceptibility and MRI outcome measures

OBJECTIVE

In addition to the main multiple sclerosis (MS) major histocompatibility complex (MHC) risk allele (HLA DRB1*1501), investigations of the MHC have implicated several class I MHC loci (HLA A, HLA B, and HLA C) as potential independent MS susceptibility loci. Here, we evaluate the role of 3 putative protective alleles in MS: HLA A*02, HLA B*44, and HLA C*05.

METHODS

Subjects include a clinic-based patient sample with a diagnosis of either MS or a clinically isolated syndrome (n = 532), compared to subjects in a bone marrow donor registry (n = 776). All subjects have 2-digit HLA data. Logistic regression was used to determine the independence of each allele's effect. We used linear regression and an additive model to test for correlation between an allele and MRI and clinical measures of disease course.

RESULTS

After accounting for the effect of HLA DRB1*1501, both HLA A*02 and HLA B*44 are validated as susceptibility alleles (p(A*02) 0.00039 and p(B*44) 0.00092) and remain significantly associated with MS susceptibility in the presence of the other allele. Although A*02 is not associated with MS outcome measures, HLA B*44 demonstrates association with a better radiologic outcome both in terms of brain parenchymal fraction and T2 hyperintense lesion volume (p = 0.03 for each outcome).

CONCLUSION

The MHC class I alleles HLA A*02 and HLA B*44 independently reduce susceptibility to MS, but only HLA B*44 appears to influence disease course, preserving brain volume and reducing the burden of T2 hyperintense lesions in subjects with MS.

Somatic FAS mutations are common in patients with genetically undefined autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) is characterized by childhood onset of lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias, elevated numbers of double-negative T (DNT) cells, and increased risk of lymphoma. Most cases of ALPS are associated with germline mutations of the FAS gene (type Ia), whereas some cases have been noted to have a somatic mutation of FAS primarily in their DNT cells. We sought to determine the proportion of patients with somatic FAS mutations among a group of our ALPS patients with no detectable germline mutation and to further characterize them. We found more than one-third (12 of 31) of the patients tested had somatic FAS mutations, primarily involving the intracellular domain of FAS resulting in loss of normal FAS signaling. Similar to ALPS type Ia patients, the somatic ALPS patients had increased DNT cell numbers and elevated levels of serum vitamin B(12), interleukin-10, and sFAS-L. These data support testing for somatic FAS mutations in DNT cells from ALPS patients with no detectable germline mutation and a similar clinical and laboratory phenotype to that of ALPS type Ia. These findings also highlight the potential role for somatic mutations in the pathogenesis of nonmalignant and/or autoimmune hematologic conditions in adults and children.

The autoimmune lymphoproliferative syndrome: A rare disorder providing clues about normal tolerance

The autoimmune lymphoproliferative syndrome (ALPS) is characterized by chronic, non-malignant lymphoproliferation, autoimmunity often manifesting as multilineage cytopenias, and an increased risk of lymphoma. While considered a rare disease, there are currently over 250 patients with ALPS being followed at the National Institutes of Health in Bethesda, Maryland. Most of these patients have a mutation in the gene for the TNF receptor-family member Fas (CD 95, Apo-1), and about one-third have an unknown defect or mutations affecting function of other signaling proteins involved in the apoptotic pathway. While ALPS is one of the few autoimmune diseases with a known genetic defect, there remain unanswered questions regarding how a defect in apoptosis results in the observed phenotype. In addition to shedding light on the pathophysiology of this rare and fascinating condition, studying ALPS may improve our understanding of normal tolerance and more common, sporadic autoimmune disorders.

Residual CD95-pathway function in children with autoimmune lymphoproliferative syndrome is independent from clinical state and genotype of CD95 mutation

Human autoimmune lymphoproliferative syndrome (ALPS) is caused by defective CD95-mediated apoptosis of lymphocytes. In most patients, heterozygous mutations within the CD95 gene are found. Mutated proteins interfere with CD95-signaling in a dominant-negative way. However, the penetrance of clinical disease is variable. We describe 13 patients out of nine families with the clinical presentation of ALPS. Eight different mutations were detected. Sensitivity to CD95-induced cell-death, assembly of the CD95-death-inducing signaling complex (DISC), and activity of initiator caspases-8 and -10 were compared in EBV-transformed B-lymphoblastoid cells of these patients. All CD95-mutations led to a reduced DISC formation and diminished initiator caspase activity upon CD95-stimulation, whereas a marked heterogeneity in sensitivity to CD95-induced killing was found. Residual apoptosis sensitivity to almost normal levels could be achieved upon cross-linking by addition of protein A. Thus, no correlation between residual CD95 sensitivity and clinical phenotype or genotype of ALPS was found. This observation is only partially explained by the variable effects of the CD95-mutations themselves. It also points to a pronounced influence of additional factors, such as modifier pathways or exogenous effects apart from the CD95 pathway in the pathogenesis of ALPS.

Dominant inhibition of Fas ligand-mediated apoptosis due to a heterozygous mutation associated with autoimmune lymphoproliferative syndrome (ALPS) Type Ib

Background:

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of lymphocyte homeostasis and immunological tolerance due primarily to genetic defects in Fas (CD95/APO-1; TNFRSF6), a cell surface receptor that regulates apoptosis and its signaling apparatus.

Methods:

Fas ligand gene mutations from ALPS patients were identified through cDNA and genomic DNA sequencing. Molecular and biochemical assessment of these mutant Fas ligand proteins were carried out by expressing the mutant FasL cDNA in mammalian cells and analysis its effects on Fas-mediated programmed cell death.

Results:

We found an ALPS patient that harbored a heterozygous A530G mutation in the FasL gene that replaced Arg with Gly at position 156 in the protein's extracellular Fas-binding region. This produced a dominant-interfering FasL protein that bound to the wild-type FasL protein and prevented it from effectively inducing apoptosis.

Conclusion:

Our data explain how a naturally occurring heterozygous human FasL mutation can dominantly interfere with normal FasL apoptotic function and lead to an ALPS phenotype, designated Type Ib.

Genetic alterations in caspase-10 may be causative or protective in autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) is characterized by lymphadenopathy, elevated numbers of T cells with alphabeta-T cell receptors but neither CD4 nor CD8 co-receptors, and impaired lymphocyte apoptosis in vitro. Defects in the Fas receptor are the most common cause of ALPS (ALPS Ia), but in rare cases other apoptosis proteins have been implicated, including caspase-10 (ALPS II). We investigated the role of variants of caspase-10 in ALPS. Of 32 unrelated probands with ALPS who did not have Fas defects, two were heterozygous for the caspase-10 missense mutation I406L. Like the previously reported ALPS II-associated mutation L285F, I406L impaired apoptosis when transfected alone and dominantly inhibited apoptosis mediated by wild type caspase-10 in a co-transfection assay. Other variants in caspase-10, V410I and Y446C, were found in 3.4 and 1.6% of chromosomes in Caucasians, and in 0.5 and <0.5% of African Americans, respectively. In contrast to L285F and I406L, these variants had no dominant negative effect in co-transfection assays into the H9 lymphocytic cell line. We found healthy individuals homozygous for V410I, challenging the earlier suggestion that homozygosity for V410I alone causes ALPS. Moreover, an association analysis suggested protection from severe disease by caspase-10 V410I in 63 families with ALPS Ia due to dominant Fas mutations (P<0.05). Thus, different genetic variations in caspase-10 can produce contrasting phenotypic effects.