Clinical, immunologic, molecular analyses and outcomes of iranian patients with LRBA deficiency: A longitudinal study

The multidisciplinary approach to diagnosing inborn errors of immunity: a comprehensive review of discipline-based manifestations

INTRODUCTION

Congenital immunodeficiency is named primary immunodeficiency (PID), and more recently inborn errors of immunity (IEI). There are more than 485 conditions classified as IEI, with a wide spectrum of clinical and laboratory manifestations.

AREAS COVERED

Regardless of the developing knowledge of IEI, many physicians do not think of IEI when approaching the patient's complaint, which leads to delayed diagnosis, misdiagnosis, serious infectious and noninfectious complications, permanent end-organ damage, and even death. Due to the various manifestations of IEI and the wide spectrum of associated conditions, patients refer to specialists in different disciplines of medicine and undergo - mainly symptomatic - treatments, and because IEI are not included in physicians' differential diagnosis, the main disease remains undiagnosed.

EXPERT OPINION

A multidisciplinary approach may be a proper solution. Manifestations and the importance of a multidisciplinary approach in the diagnosis of main groups of IEI are discussed in this article.

Comparison of Post-Vaccination Cellular Immune Response in Patients with Common Variable Immune Deficiency

BACKGROUND

The problem of identifying vaccine-specific T-cell responses is still a matter of debate. Currently, there are no universal, clearly defined, agreed upon criteria for assessing the effectiveness of vaccinations and their immunogenicity for the cellular component of immunity, even for healthy people. But for patients with inborn errors of immunity (IEI), especially those with antibody deficiencies, evaluating cellular immunity holds significant importance.

AIM

To examine the effect of one and two doses of inactivated adjuvanted subunit influenza vaccines on the expression of endosomal Toll-like receptors (TLRs) on the immune cells and the primary lymphocyte subpopulations in patients with common variable immunodeficiency (CVID).

MATERIALS AND METHODS

During 2018-2019, six CVID patients received one dose of a quadrivalent adjuvanted influenza vaccine; in 2019-2020, nine patients were vaccinated with two doses of a trivalent inactivated influenza vaccine. The proportion of key lymphocyte subpopulations and expression levels of TLRs were analyzed using flow cytometry with monoclonal antibodies.

RESULTS

No statistically significant alterations in the absolute values of the main lymphocyte subpopulations were observed in CVID patients before or after vaccination with the different immunization protocols. However, after vaccination, a higher expression of TLR3 and TLR9 in granulocytes, monocytes, and lymphocytes was found in those patients who received two vaccine doses rather than one single dose.

CONCLUSION

This study marks the first instance of using a simultaneous two-dose vaccination, which is associated with an elevated level of TLR expression in the immune cells. Administration of the adjuvanted vaccines in CVID patients appears promising. Further research into their impact on innate immunity and the development of more effective vaccination regimens is warranted.

Analysis of LRBA pathogenic variants and the association with functional protein domains and clinical presentation

LRBA is a cytoplasmic protein that is ubiquitously distributed. Almost all LRBA domains have a scaffolding function. In 2012, it was reported that homozygous variants in LRBA are associated with early-onset hypogammaglobulinemia. Since its discovery, more than 100 pathogenic variants have been reported. This review focuses on the variants reported in LRBA and their possible associations with clinical phenotypes. In this work LRBA deficiency cases reported more than 11 years ago have been revised. A database was constructed to analyze the type of variants, age at onset, clinical diagnosis, infections, autoimmune diseases, and cellular and immunoglobulin levels. The review of cases from 2012 to 2023 showed that LRBA deficiency was commonly diagnosed in patients with a clinical diagnosis of Common Variable Immunodeficiency, followed by enteropathy, neonatal diabetes mellitus, ALPS, and X-linked-like syndrome. Most cases show early onset of presentation at <6 years of age. Most cases lack protein expression, whereas hypogammaglobulinemia is observed in half of the cases, and IgG and IgA levels are isotypes reported at low levels. Patients with elevated IgG levels exhibited more than one autoimmune manifestation. Patients carrying pathogenic variants leading to a premature stop codon show a severe phenotype as they have an earlier onset of disease presentation, severe autoimmune manifestations, premature death, and low B cells and regulatory T cell levels. Missense variants were more common in patients with low IgG levels and cytopenia. This work lead to the conclusion that the type of variant in LRBA has association with disease severity, which leads to a premature stop codon being the ones that correlates with severe disease.

Construction of ceRNA regulatory networks for active pulmonary tuberculosis

Delayed diagnosis in patients with pulmonary tuberculosis (PTB) often leads to serious public health problems. High throughput sequencing was used to determine the expression levels of lncRNAs, mRNAs, and miRNAs in the lesions and adjacent health lung tissues of patients with PTB. Their differential expression profiles between the two groups were compared, and 146 DElncRs, 447 DEmRs, and 29 DEmiRs were obtained between lesions and adjacent health tissues in patients with PTB. Enrichment analysis for mRNAs showed that they were mainly involved in Th1, Th2, and Th17 cell differentiation. The lncRNAs, mRNAs with target relationship with miRNAs were predicted respectively, and correlation analysis was performed. The ceRNA regulatory network was obtained by comparing with the differentially expressed transcripts (DElncRs, DEmRs, DEmiRs), then 2 lncRNAs mediated ceRNA networks were established. The expression of genes within the network was verified by quantitative real-time PCR (qRT-PCR). Flow cytometric analysis revealed that the proportion of Th1 cells and Th17 cells was lower in PTB than in controls, while the proportion of Th2 cells increased. Our results provide rich transcriptome data for a deeper investigation of PTB. The ceRNA regulatory network we obtained may be instructive for the diagnosis and treatment of PTB.

Interstitial lung diseases in inborn errors of immunity

PURPOSE OF REVIEW

Our goal is to review current understanding of interstitial lung disease (ILD) affecting patients with inborn errors of immunity (IEI). This includes understanding how IEI might predispose to and promote development or progression of ILD as well as how our growing understanding of IEI can help shape treatment of ILD in these patients. Additionally, by examining current knowledge of ILD in IEI, we hope to identify key knowledge gaps that can become focus of future investigative efforts.

RECENT FINDINGS

Recent identification of novel IEI associated with ILD and the latest reports examining treatment of ILD in IEI are included. Of noted interest, are recent clinical studies of immunomodulatory therapy for ILD in common variable immunodeficiency.

SUMMARY

ILD is a frequent complication found in many IEI. This article provides a guide to identifying manifestations of ILD in IEI. We review a broad spectrum of IEI that develop ILD, including antibody deficiency and immune dysregulation disorders that promote autoimmunity and autoinflammation. This work integrates clinical information with molecular mechanisms of disease and diagnostic assessments to provide an expedient overview of a clinically relevant and expanding topic.

Voxelotor Treatment Providing Transfusion Independence for Patient With Combined Sickle Cell Disease and Lipopolysaccharide-Responsive and Beige-Like Anchor (LRBA) Deficiency

We present a 22-year-old female with transfusion-dependent anemia due to sickle cell disease (SCD) with lipopolysaccharide-responsive and beige-like anchor protein (LRBA) deficiency whose treatment frequency was moderated with voxelotor (Oxbryta®). The patient was transfusion dependent, initially thought to be secondary only to SCD. After the diagnosis of LRBA deficiency, her regimen included abatacept, sirolimus, hydroxyurea, and folic acid, but she still required intermittent transfusion. She was started on voxelotor in January 2020. Since initiation, her baseline hemoglobin level has increased and she is no longer transfusion dependent.

Central nervous system manifestations of LRBA deficiency: case report of two siblings and literature review

BACKGROUND

LPS-responsive beige-like anchor protein (LRBA) deficiency is a primary immunodeficiency disease (PID) characterized by a regulatory T cell defect resulting in immune dysregulation and autoimmunity. We present two siblings born to consanguineous parents of North African descent with LRBA deficiency and central nervous system (CNS) manifestations. As no concise overview of these manifestations is available in literature, we compared our patient's presentation with a reviewed synthesis of the available literature.

CASE PRESENTATIONS

The younger brother presented with enteropathy at age 1.5 years, and subsequently developed Evans syndrome and diabetes mellitus. These autoimmune manifestations led to the genetic diagnosis of LRBA deficiency through whole exome sequencing with PID gene panel. At 11 years old, he had two tonic-clonic seizures. Brain MRI showed multiple FLAIR-hyperintense lesions and a T2-hyperintense lesion of the cervical medulla.  His sister presented with immune cytopenia at age 9 years, and developed diffuse lymphadenopathy and interstitial lung disease. Genetic testing confirmed the same mutation as her brother. At age 13 years, a brain MRI showed multiple T2-FLAIR-hyperintense lesions. She received an allogeneic hematopoietic stem cell transplantation (allo-HSCT) 3 months later. Follow-up MRI showed regression of these lesions.

CONCLUSIONS

Neurological disease is documented in up to 25% of patients with LRBA deficiency. Manifestations range from cerebral granulomas to acute disseminating encephalomyelitis, but detailed descriptions of neurological and imaging phenotypes are lacking. LRBA deficiency amongst other PIDs should be part of the differential diagnosis in patients with inflammatory brain lesions. We strongly advocate for a more detailed description of CNS manifestations in patients with LRBA deficiency, when possible with MR imaging. This will aid clinical decision concerning both anti-infectious and anti-inflammatory therapy and in considering the indication for allo-HSCT.

Type 1 diabetes and inborn errors of immunity: Complete strangers or 2 sides of the same coin?

Type 1 diabetes (T1D) is a polygenic disease and does not follow a mendelian pattern. Inborn errors of immunity (IEIs), on the other hand, are caused by damaging germline variants, suggesting that T1D and IEIs have nothing in common. Some IEIs, resulting from mutations in genes regulating regulatory T-cell homeostasis, are associated with elevated incidence of T1D. The genetic spectrum of IEIs is gradually being unraveled; consequently, molecular pathways underlying human monogenic autoimmunity are being identified. There is an appreciable overlap between some of these pathways and the genetic variants that determine T1D susceptibility, suggesting that after all, IEI and T1D are 2 sides of the same coin. The study of monogenic IEIs with a variable incidence of T1D has the potential to provide crucial insights into the mechanisms leading to T1D. These insights contribute to the definition of T1D endotypes and explain disease heterogeneity. In this review, we discuss the interconnected pathogenic pathways of autoimmunity, β-cell function, and primary immunodeficiency. We also examine the role of environmental factors in disease penetrance as well as the circumstantial evidence of IEI drugs in preventing and curing T1D in individuals with IEIs, suggesting the repositioning of these drugs also for T1D therapy.

Case report: A new pathogenic variant of LRBA deficiency with a complex phenotype and Rosai-Dorfman disease

We reported a new pathogenic variant of LRBA deficiency with a complex phenotype-neonatal diabetes, very early-onset inflammatory bowel disease, and polyarthritis-who presented with lymph node enlargement. A case of Rosai-Dorfman's disease (RDD) was confirmed. The occurrence of an RDD lesion in LRBA-deficiency has never been reported so far.

Targeted next-generation sequencing revealed a novel homozygous mutation in the LRBA gene causes severe haemolysis associated with Inborn Errors of Immunity in an Indian family

OBJECTIVES

LPS-responsive beige-like anchor protein (LRBA) deficiency abolishes LRBA protein expression due to biallelic mutations in the LRBA gene that lead to autoimmune manifestations, inflammatory bowel disease, hypogammaglobulinemia in early stages, and variable clinical manifestations.

MATERIALS AND METHODS

Mutational analysis of the LRBA gene was performed in Indian patients using targeted Next Generation Sequencing (t-NGS) and confirmed by Sanger sequencing using specific primers of exons 53. Then, bioinformatics analysis and protein modeling for the novel founded mutations were also performed. The genotype, phenotype correlation was done according to the molecular findings and clinical features.

RESULTS

We report an unusual case of a female patient born of a consanguineous marriage, presented with severe anaemia and jaundice with a history of multiple blood transfusions of unknown cause up to the age of 5 yrs. She had hepatosplenomegaly with recurrent viral and bacterial infections. Tests for hemoglobinopathies, enzymopathies, and hereditary spherocytosis were within the normal limits. The t-NGS revealed a novel homozygous missense variation in exon 53 of the LRBA gene (chr4:151231464C > T; c.7799G > A) (p.C2600Y), and the parents were heterozygous. The further immunological analysis is suggestive of hypogammaglobulinaemia and autoimmune haemolytic anaemia. The bioinformatics tools are suggestive of deleterious and disease-causing variants.

CONCLUSION

This study concludes the importance of a timely decision of targeted exome sequencing for the molecular diagnostic tool of unexplained haemolytic anaemia with heterogeneous clinical phenotypes.

Primary immune regulatory disorders: Undiagnosed needles in the haystack?

Primary Immune Regulatory Disorders (PIRD) describe a group of conditions characterized by loss of normal inflammatory control and immune tolerance mechanisms, with autoimmunity as a predominant clinical feature. PIRD can arise due to defects in the number or function of regulatory T-lymphocytes, defects in the immune mechanisms required to ‘turn off’ inflammation such as in perforin-dependent cytotoxicity or alterations in cytokine signalling pathways. Diagnosis of PIRD is a significant challenge to physicians due to their rarity, complexity, and diversity in clinical manifestations. Many of these individual conditions lack a genotype–phenotype correlation and display incomplete penetrance. However, establishing a diagnosis is integral in optimizing patient management, including the use of individualized treatment approaches. Increasing awareness among physicians is necessary as patients are likely to present to different subspecialties. Due to the rarity of these conditions, worldwide collaboration and data-sharing is essential to improve our knowledge of the clinical spectrum and disease course in PIRD, and to optimize therapeutic strategies including identification of which patients can benefit from hematopoietic stem cell transplant.

Clinical Courses of IKAROS and CTLA4 Deficiencies: A Systematic Literature Review and Retrospective Longitudinal Study

IKAROS and CTLA4 deficiencies are inborn errors of immunity and show similar clinical phenotypes, including hypogammaglobulinemia and autoimmune diseases (ADs). However, the differences in clinical features and pathogenesis of these are not fully understood. Therefore, we performed systematic literature reviews for IKAROS and CTLA4 deficiencies. The reviews suggested that patients with IKAROS deficiency develop AD earlier than hypogammaglobulinemia. However, no study assessed the detailed changes in clinical manifestations over time; this was likely due to the cross-sectional nature of the studies. Therefore, we conducted a retrospective longitudinal study on IKAROS and CTLA4 deficiencies in our cohort to evaluate the clinical course over time. In patients with IKAROS deficiency, AD and hypogammaglobulinemia often develop in that order, and AD often resolves before the onset of hypogammaglobulinemia; these observations were not found in patients with CTLA4 deficiency. Understanding this difference in the clinical course helps in the clinical management of both. Furthermore, our results suggest B- and T-cell-mediated ADs in patients with IKAROS and CTLA4 deficiencies, respectively.

Host Defenses to Viruses: Lessons from Inborn Errors of Immunity

The constant battle between viruses and their hosts leads to their reciprocal evolution. Viruses regularly develop survival strategies against host immunity, while their ability to replicate and disseminate is countered by the antiviral defense mechanisms that host mount. Although most viral infections are generally controlled by the host’s immune system, some viruses do cause overt damage to the host. The outcome can vary widely depending on the properties of the infecting virus and the circumstances of infection but also depends on several factors controlled by the host, including host genetic susceptibility to viral infections. In this narrative review, we provide a brief overview of host immunity to viruses and immune-evasion strategies developed by viruses. Moreover, we focus on inborn errors of immunity, these being considered a model for studying host response mechanisms to viruses. We finally report exemplary inborn errors of both the innate and adaptive immune systems that highlight the role of proteins involved in the control of viral infections.

Role of rare immune cells in common variable immunodeficiency

Common variable immunodeficiency disorder (CVID) is a heterogeneous disorder and the most common symptomatic antibody deficiency disease characterized with hypogammaglobulinemia and a broad range of clinical manifestations. Multiple genetic, epigenetic, and immunological defects are involved in the pathogenesis of CVID. These immunological defects include abnormalities in the number and/or function of B lymphocytes, T lymphocytes, and other rare immune cells. Although some immune cells have a relatively lower proportion among total immune subsets in the human body, they could have important roles in the pathogenesis of immunological disorders like CVID. To the best of our knowledge, this is the first review that described the role of rare immune cells in the pathogenesis and clinical presentations of CVID.

The pediatric common variable immunodeficiency - from genetics to therapy: a review

Common variable immunodeficiency (CVID) is the most prevalent antibody deficiency, characterized by remarkable genetic, immunological, and clinical heterogeneity. The diagnosis of pediatric CVID is challenging due to the immaturity of the immune response and sustained actively developing antibody affinity to antigens and immunological memory that may overlap with the inborn error of immunity. Significant progress has been recently done in the field of immunogenetics, yet a paucity of experimental and clinical studies on different systemic manifestations and immunological features of CVID in children may contribute to a delayed diagnosis and therapy. In this review, we aimed at defining the variable epidemiological, etiological, and clinical aspects of pediatric CVID with special emphasis on predominating infectious and non-infectious phenotypes in affected children.

CONCLUSION

While pediatric CVID is a multifaceted and notorious disease, increasing the pediatricians' awareness of this disease entity and preventing the diagnostic and therapeutic delay are needed, thereby improving the prognosis and survival of pediatric CVID patients.

WHAT IS KNOWN

• CVID is an umbrella diagnosis characterized by complex pathophysiology with an antibody deficiency as a common denominator. • It is a multifaceted disease characterized by marked genetic, immunological, and clinical heterogeneity..

WHAT IS NEW

• The diagnosis of pediatric CVID is challenging due to the immaturity of innate and adaptive immune response. • Increasing the pediatricians' awareness of CVID for the early disease recognition, timely therapeutic intervention, and improving the prognosis is needed.

Common variable immunodeficiency: different faces of the same disease

Introduction

Common variable immunodeficiency (CVID) is one of the primary humoral immunodeficiencies. Despite the inborn nature, the first symptoms may appear in both children and adults. It is characterized by hypogammaglobulinaemia, severe infections, autoimmunity, allergies, and a predisposition to cancer. A delay in diagnosis is a significant problem: the time from the first symptoms of the disease to diagnosis and the implementation of proper treatment is usually very long. The consequence can be irreversible complications, which is why it is so important to promote knowledge on this immunodeficiency.

Aim

To present the clinical and laboratory manifestation of primary immunodeficiencies such as common variable immunodeficiency.

Material and methods

The study presents the clinical and laboratory phenotype of 14 patients diagnosed with CVID, aged 5 to 58 years. A detailed medical history was taken, and clinical symptoms, immunological test results and complications were analysed in each patient. According to the ESID guidelines, in the differential diagnosis process of CVID the secondary hypogammaglobulinaemia was excluded.

Results

The follow-up period ranged from 39 to 133 months (median: 79 months). The median delay for the entire group was 5 years, which was shorter in children than in adults. In the presented group, the infectious phenotype (pneumonia, sinusitis) was dominant. Autoimmune and allergic diseases, malignant tumours and enteropathies have also been observed.

Conclusions

The diagnostic delay is still too long, especially in adults, which can lead to serious and irreversible complications. Early diagnosis and appropriate treatment with intravenous and subcutaneous immunoglobulins reduces the frequency of infections and their potential complications.

Autoimmune manifestations among 461 patients with monogenic inborn errors of immunity

BACKGROUND

The inborn errors of immunity (IEIs) are a group of heterogeneous disorders mainly characterized by severe and recurrent infections besides other complications including autoimmune and inflammatory diseases. In this study, we aim to evaluate clinical, immunologic, and molecular data of monogenic IEI patients with and without autoimmune manifestations.

METHODS

We have retrospectively screened cases of monogenic IEI in the Iranian PID registry for the occurrence of autoimmunity and immune dysregulation. A questionnaire was filled for all qualified patients with monogenic defects to evaluate demographic, laboratory, clinical, and molecular data.

RESULTS

A total of 461 monogenic IEI patients (290 male and 171 female) with a median (IQR) age of 11.0 (6.0-20.0) years were enrolled in this study. Overall, 331 patients (72.1%) were born to consanguineous parents. At the time of the study, 330 individuals (75.7%) were alive and 106 (24.3%) were deceased. Autoimmunity was reported in 92 (20.0%) patients with a median (IQR) age at autoimmune diagnosis of 4.0 (2.0-7.0) years. Sixteen patients (3.5%) showed autoimmune complications (mostly autoimmune cytopenia) as the first presentation of the disease. Most of the patients with autoimmunity were diagnosed clinically with common variable immunodeficiency (42.4%). The frequency of sinusitis and splenomegaly was significantly higher in patients with autoimmunity than patients without autoimmunity. In patients with autoimmunity, the most common pathogenic variants were identified in LRBA (in 21 patients, 23.0%), ATM (in 13 patients, 14.0%), and BTK (in 9 patients, 10.0%) genes. In the evaluation of autoimmunity by different genes, 4 of 4 IL10RB (100%), 3 of 3 AIRE (100%), and 21 of 30 LRBA (70.0%) mutated genes had the highest prevalence of autoimmunity.

CONCLUSIONS

Autoimmune phenomena are common features among patients with monogenic IEI and are associated with a more complicated course of the disease. Therefore, when encountering autoimmune disorders, especially in the setting of dysgammaglobulinemia, it would be appropriate to conduct next-generation sequencing to discover responsible genes for the immune dysregulation at an early stage of the disease.

Potential protein–phenotype correlation in three lipopolysaccharide-responsive beige-like anchor protein-deficient patients

BACKGROUND

Patients with lipopolysaccharide (LPS)-responsive beige-like anchor protein (LRBA) deficiency have a variety of clinical symptoms, but there is no apparent genotype–phenotype correlation, and patients carrying the same mutations may have different phenotypes. Therefore, it is not easy for doctors to make a decision regarding hematopoietic stem cell transplantation (HSCT) for LRBA-deficient patients. We hypothesized that there may be a protein–phenotype correlation to indicate HSCT for LRBA-deficient patients.

AIM

To report on three Chinese LRBA-deficient patients and determine the correlation between residual protein expression and disease phenotypes.

METHODS

Clinical data of three Chinese LRBA-deficient patients were collected, and protein levels were detected by Western blot analysis. In addition, LRBA mutation information of another 83 previously reported patients was summarized.

RESULTS

All the major clinical findings indicated enteropathy, but patients 1 and 3 presented with more severe symptoms than patient 2. Endoscopy and histology indicated nonspecific colitis for patients 1 and 3 but Crohn's disease-like colitis for patient 2. Compound heterozygous mutations in LRBA were found in patient 1, and homozygous mutations in LRBA were found in patient 2 and patient 3. Only patient 2 responded well to traditional immunosuppressive treatment. Residual expression of the LRBA protein in patients 1 and 3 was very low, but in patient 2, a more than 0.5-fold in expression of the LRBA protein was found compared to that in the control. After HSCT, patient 1 had increased LRBA protein expression. We summarized the genetic information of 86 patients, and the mutations in patients 1 and 3 were novel mutations.

CONCLUSION

We described three Chinese LRBA-deficient patients, two of whom carried novel mutations. These patients had no genotype-phenotype correlations, but their residual LRBA protein expression might be associated with disease outcome and could be an indicator for HSCT.

Pulmonary manifestations of immune dysregulation in CTLA-4 haploinsufficiency and LRBA deficiency

OBJECTIVE

The primary immunodeficiency syndromes of cytotoxic T lymphocyte-associated protein 4 (CTLA-4) haploinsufficiency and lipopolysaccharide-responsive and beige-like anchor protein (LRBA) deficiency present with multisystem immune dysregulation. The aim of this study was to characterize and compare the pulmonary manifestations of these two diseases.

METHODS

We retrospectively analyzed the pulmonary clinical, radiologic, and histopathologic characteristics of six patients with CTLA-4 haploinsufficiency and four patients with LRBA deficiency with pulmonary involvement followed at a large tertiary care center.

RESULTS

Chronic respiratory symptoms were more frequent in patients with LRBA deficiency versus CTLA-4 haploinsufficiency (3/4 vs. 1/6). Cough was the most common respiratory symptom. Abnormalities in pulmonary exam and pulmonary function testing were more frequent in LRBA deficiency (4/4, 2/4) compared to CTLA-4 haploinsufficiency (1/6, 2/6). Chest computed tomography (CT) findings included mediastinal lymphadenopathy (4/4 in LRBA deficiency vs. 1/4 in CTLA-4 haploinsufficiency), pulmonary nodules (4/4, 3/4), ground-glass opacification (4/4, 3/4), and bronchiectasis (3/4, 1/4). Lymphocytic inflammation, concentrated bronchovasculocentrically and paraseptally, was the predominant pathologic finding and was observed in all patients who had lung biopsies (N = 3 with LRBA deficiency; N = 3 with CTLA-4 haploinsufficiency).

CONCLUSION

Despite phenotypic overlap amongst these diseases, LRBA deficiency demonstrated greater severity of pulmonary disease, indicated by respiratory symptoms, pulmonary exam, and intrathoracic radiologic findings. Chest CT was the most sensitive indicator of pulmonary involvement in both disorders. Lymphocytic inflammation is the key histologic feature of both disorders. Pediatric pulmonologists should consider these disorders of immune dysregulation in the relevant clinical context to provide earlier diagnosis, comprehensive pulmonary evaluation and treatment.

LRBA deficiency: a rare cause of type 1 diabetes, colitis, and severe immunodeficiency

The biological role of the lipopolysaccharide-responsive beige-like anchor (LRBA) protein associated with the immune system is not to date well known. However, it is thought to regulate the CTLA4 protein, an inhibitory immunoreceptor. Chronic diarrhea, autoimmune disorders, organomegaly, frequent recurrent infections, hypogammaglobulinemia, chronic lung manifestations, and growth retardation are some features of LRBA deficiency. This rare disease is observed as a result of homozygous mutations in the LRBA gene. An 11.3-year-old male patient presented because of short stature and high blood glucose level. He had a previous history of lymphoproliferative disease, chronic diarrhea, and recurrent infections. His parents were first-degree consanguineous relatives. A diagnosis of type 1 diabetes mellitus (T1DM) was added to the preexisting diagnoses of immunodeficiency, recurrent infection, enteropathy, chronic diarrhea, lymphadenopathy, hepatomegaly, and short stature. Genetic analysis revealed a homozygous mutation in the LRBA gene, c.5047C>T (p.R1683*) (p.Arg1683*). Abatacept treatment was started: the patient's hospital admission frequency decreased, and glucose regulation improved. At follow-up, growth hormone (GH) deficiency was diagnosed, although it was not treated because the underlying disease was not under control. Nevertheless, the patient's height improved with abatacept treatment. LRBA deficiency should be considered in the presence of consanguineous marriage, diabetes, immunodeficiency, and additional autoimmune symptoms. LRBA phenotypes are variable even when the same variants in the LRBA gene are present. Genetic diagnosis is important to determine optimal treatment options. In addition to chronic malnutrition and immunosuppressive therapy, GH deficiency may be one of the causes of short stature in these patients.

Novel compound heterozygous LRBA deletions in a 6-month-old with neonatal diabetes

We report a 6-month-old boy with antibody-positive insulin-dependent diabetes mellitus. Sequencing identified compound heterozygous deletions of exon 5 and exons 36-37 in LRBA. At three years, he has yet to exhibit any other immune symptoms. Genetic testing of LRBA is warranted in patients with neonatal diabetes, even without immune dysregulation.

Different Apples, Same Tree: Visualizing Current Biological and Clinical Insights into CTLA-4 Insufficiency and LRBA and DEF6 Deficiencies

Cytotoxic T lymphocyte antigen-4 (CTLA-4) is a crucial immune checkpoint that is constitutively expressed in regulatory T (Treg) cells. Following T-cell activation, CTLA-4 is rapidly mobilized from its intracellular vesicle pool to the cell surface to control the availability of co-stimulatory B7 molecules, thereby maintaining immune homeostasis. Heterozygous mutations in CTLA-4 lead to defects in (i) CTLA-4 ligand binding, (ii) homo-dimerization, (iii) B7-transendocytosis, and (iv) CTLA-4 vesicle trafficking, resulting in an inborn error of immunity with predominant autoimmunity. CTLA-4 vesicle trafficking impairment is also observed in patients with lipopolysaccharide-responsive beige-like anchor protein (LRBA) deficiency or the differentially expressed in FDCP6 homolog (DEF6) deficiency, caused by biallelic mutations in LRBA and DEF6, respectively. Therefore, patients with CTLA-4 insufficiency, LRBA deficiency, and-most recently reported-DEF6 deficiency present an overlapping clinical phenotype mainly attributed to a defective suppressive activity of Tregs, as all three diseases reduce overall surface expression of CTLA-4. In this paper, we describe the clinical phenotypes of these immune checkpoint defects, their patho-mechanisms, and visually compare them to other immune regulatory disorders (IPEX syndrome, CD27, and CD70 deficiencies) by using the immune deficiency and dysregulation (IDDA version 2.1) "kaleidoscope" score. This illustrates the variability of the degrees and manifestations of immune deficiency and dysregulation. Patients characteristically present with an increased risk of infections, autoimmune cytopenias, multi-organ autoimmunity, and inflammation, which are often severe and life-threatening. Furthermore, these patients suffer an increased risk of developing malignancies, especially Non-Hodgkin's lymphoma. Successful treatment options include regular administration of soluble CTLA-4-Ig fusion protein, Treg cell-sparing immune suppressants like sirolimus or mycophenolate mofetil, and hematopoietic stem cell transplantation. This mini-review highlights the most relevant biological and clinical features as well as treatment options for CTLA-4 insufficiency and LRBA and DEF6 deficiencies.

Immune checkpoint deficiencies and autoimmune lymphoproliferative syndromes

Autoimmune lymphoproliferative syndrome (ALPS) is an inherited non-malignant and non-infectious lymphoproliferative syndrome caused by mutations in genes affecting the extrinsic apoptotic pathway (FAS, FASL, CASP10). The resulting FAS-mediated apoptosis defect accounts for the expansion and accumulation of autoreactive (double-negative) T cells leading to cytopenias, splenomegaly, lymphadenopathy, autoimmune disorders, and risk of lymphoma. However, there are other monogenetic disorders known as ALPS-like syndromes that can be clinically similar to ALPS but are genetically and biologically different, such as observed in patients with immune checkpoint deficiencies, particularly cytotoxic T-lymphocyte antigen 4 (CTLA-4) insufficiency and lipopolysaccharide-responsive beige-like anchor protein LRBA deficiency. CTLA-4 insufficiency is caused by heterozygous mutations in CTLA-4, an essential negative immune regulator that is constitutively expressed on regulatory T (Treg) cells. Mutations in CTLA-4 affect CTLA-4 binding to CD80-CD86 costimulatory molecules, CTLA-4 homodimerization, or CTLA-4 intracellular vesicle trafficking upon cell activation. Abnormal CTLA-4 trafficking is also observed in patients with LRBA deficiency, a syndrome caused by biallelic mutations in LRBA that abolishes the LRBA protein expression. Both immune checkpoint deficiencies are biologically characterized by low levels of CTLA-4 protein on the cell surface of Tregs, accounting for the autoimmune manifestations observed in CTLA4-insufficient and LRBA-deficient patients. In addition, both immune checkpoint deficiencies present with an overlapping but heterogeneous clinical picture despite the difference in inheritance and penetrance. In this review, we describe the most prominent clinical features of ALPS, CTLA-4 insufficiency and LRBA deficiency, emphasizing their corresponding biological mechanisms. We also provide some clinical and laboratory approaches to diagnose these three rare immune disorders, together with therapeutic strategies that have worked best at improving prognosis and quality life of patients.

Leishmaniasis and Autoimmunity in Patient with LPS-Responsive Beige-Like Anchor Protein (LRBA) Deficiency

BACKGROUND/OBJECTIVE

LPS-responsive beige-like anchor protein (LRBA) deficiency is a combined immunodeficiency and immune dysregulation. The authors present a case report of LPSresponsive beige-like anchor protein (LRBA) deficiency with the history of autoimmunity, enteropathy and visceral leishmaniasis. Sirolimus therapy was started for autoimmunity and enteropathy but was discontinued due to recurrent leishmaniasis. Therefore, a common side-effect of many immunosuppressive drugs in patients with LRBA deficiency is increased susceptibility to infections.

METHODS

Whole exome sequencing was performed to detect the underlying genetic mutation and Leishmania DNA was detected by the PCR technique in this patient.

RESULTS

Whole exome sequencing of the patient reported a homozygous frameshift deletion mutation in the LRBA gene (NM_006726: exon29: c.4638delC, p. S1546fs). Leishmania DNA PCR was positive in this case.

CONCLUSION

Parasite infections manifestations report in LRBA deficiency. Leishmania infections in patients with chronic diarrhea and autoimmunity should be considered for immunodeficiency.

Evaluation of Expression of LRBA and CTLA-4 Proteins in Common Variable Immunodeficiency Patients

Common variable immunodeficiency (CVID) is a primary immunodeficiency disease with a heterogeneous genetic background. Lipopolysaccharide-responsive beige-like anchor (LRBA), as well as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), have important regulatory roles in the immune responses. Here, we have investigated the expression of LRBA and CTLA-4 proteins in CVID patients with at least one presentation of early-onset occurrence, autoimmunity, or enteropathy. In this study, 20 newly diagnosed CVID patients without infection only phenotype, and ten healthy individuals were enrolled. The expressions of LRBA and CTLA-4 proteins were assessed by western blotting and flow cytometry, respectively. The patients were divided into two groups of autoimmunity-positive (11 cases) and autoimmunity-negative (9 patients). LRBA and CTLA-4 expressions were significantly lower in autoimmune-positive patients than in healthy individuals (P = .03 and P = .03, respectively). Autoimmune-negative patients had lower expression of LRBA and CTLA-4 than the control group, although it was not significant. There was a positive correlation between the expressions of LRBA and CTLA-4 in both groups of patients (P < .05). Furthermore, the highest frequency of LRBA (85.7%) and CTLA-4 (71.4%) defects was detected in those with concomitant presence of autoimmunity, enteropathy, and early-onset occurrence. Concurrent presence of autoimmunity, enteropathy, and early-onset occurrence in CVID patients could be indicative of a lack of expression in LRBA and CTLA-4 proteins. This could be helpful in early diagnosis and initiation of appropriate treatment in these patients prior to genetic confirmation.

Patterns of Immune Dysregulation in Primary Immunodeficiencies: A Systematic Review

BACKGROUND

Immune dysregulation is as important as susceptibility to infection in defining primary immunodeficiencies (PIDs). Because of the variability and nonspecificity of the symptoms of PIDs, diagnosis can be delayed-especially if a patient presents with immune dysregulation. Diagnosis is then based on certain combinations of symptoms and relies on the clinician's ability to recognize a pattern. So far there is no large report linking patterns of immune dysregulations to the underlying genetic defects.

OBJECTIVE

To identify immune dysregulatory patterns associated with PIDs and to help clinicians to detect an underlying PID in certain patients with noninfectious inflammatory diseases.

METHOD

A systematic literature review was performed.

RESULTS

We included 186 articles that reported on n = 745 patients. The most common immune dysregulation category was "autoimmunity" (62%, n = 463), followed by "intestinal disease" (38%, n = 283) and "lymphoproliferation" (36%, n = 268). Most patients (67%) had 1 or more symptoms of immune dysregulation. Autoimmune hemolytic anemia, the most common autoimmune phenotype, was most frequently reported in patients with LPS responsive beige-like anchor protein deficiency (when combined with hypogammaglobulinemia or gastrointestinal symptoms), activation-induced cytidine deaminase deficiency (when combined with autoimmune hepatitis), or RAG1 deficiency (when it was the only symptom of immune dysregulation). Eczema, allergies, and asthma were reported in 34%, 4%, and 4% of the patients, respectively.

CONCLUSION

Patterns of immune dysregulation may help the physician to recognize specific PIDs. This systematic review provides clinicians with an overview to better assess patients with immune dysregulation.

Monogenic Inflammatory Bowel Disease: It's Never Too Late to Make a Diagnosis

Background: More than 50 different monogenic disorders have been identified as directly causing inflammatory bowel diseases, typically manifesting in the first years of life. We present the clinical course and immunological work-up of an adult patient who presented in adolescent years with an atypical gastrointestinal phenotype and was diagnosed more than two decades later with a monogenic disorder with important therapeutic implications.

Methods: Whole exome sequencing was performed in a 37-years-old patient with a history of diarrhea since adolescence. Sanger sequencing was used to validate the suspected variant. Mass cytometry (CyTOF) and flow cytometry were conducted on peripheral blood mononuclear cells for deep immunophenotyping. Next-generation sequencing of the TCRB and IgH was performed for global immune repertoire analysis of circulating lymphocytes.

Results: We identified a novel deleterious c.1455C>A (p.Y485X) mutation in LRBA. CyTOF studies demonstrated significant changes in immune landscape in the LRBA-deficient patient, including an increase in myeloid derived suppressor cells and double-negative T cells, decreased B cells, low ratio of naïve:memory T cells, and reduced capacity of T cells to secrete various cytokines following stimulation, including tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ). In addition, this patient exhibited low frequency of regulatory T cells, with a reduction in their CTLA4 expression and interleukin (IL)-10 secretion. Finally, we show marked oligoclonal expansion of specific B- and T-cell clones in the peripheral blood of the LRBA-deficient patient.

Conclusions: LRBA deficiency is characterized by marked immunological changes in innate and adaptive immune cells. This case highlights the importance of advanced genetic studies in patients with a unique phenotype, regardless of their age at presentation.

Clinical Phenotypes and Immunological Characteristics of 18 Egyptian LRBA Deficiency Patients

LPS-responsive beige-like anchor (LRBA) deficiency is an autosomal recessive primary immunodeficiency disorder, OMIM (#614700). LRBA deficiency patients suffer from variable manifestations including recurrent infections, immune dysregulation, autoimmunity, cytopenias, and enteropathy. This study describes different clinical phenotypes and immunological characteristics of 18 LRBA deficiency patients diagnosed from Egypt. T and B lymphocyte subpopulations, LRBA, and cytotoxic T lymphocyte-associated protein 4 (CTLA4) expression were evaluated in resting and stimulated T cells using flow cytometry. Next-generation sequencing was used to identify mutations in the LRBA gene. LRBA deficiency patients had significantly lower B cells and increased percentage of memory T cells. CTLA4 levels were lower in LRBA-deficient T regulatory cells in comparison to healthy donors at resting conditions and significantly increased upon stimulation of T cells. We identified 11 novel mutations in LRBA gene ranging from large deletions to point mutations. Finally, we were able to differentiate LRBA-deficient patients from healthy control and common variable immunodeficiency patients using a simple flow cytometry test performed on whole blood and without need to prior stimulation. LRBA deficiency has heterogeneous phenotypes with poor phenotype-genotype correlation since the same mutation may manifest differently even within the same family. Low LRBA expression, low numbers of B cells, increased numbers of memory T cells, and defective CTLA4 expression (which increase to normal level upon T cell stimulation) are useful laboratory tests to establish the diagnosis of LRBA deficiency. Screening of the siblings of affected patients is very important as patients may be asymptomatic at the beginning of the disease course.

Identifying Novel Mutations in Iranian Patients with LPS-responsive Beige-like Anchor Protein (LRBA) Deficiency

LPS-responsive beige-like anchor protein (LRBA) deficiency is a monogenic primary immunodeficiency characterized by a heterogeneous spectrum of clinical manifestations associated with immune dysregulation. In this study, we reported clinical, immunologic, and genetic evaluation of two Iranian patients from unrelated families, both suffering from recurrent respiratory tract infections, failure to thrive, interstitial lung disease, autoimmune cytopenia, and hypogammaglobulinemia. Pulmonary abscess in one patient and persistent enteropathy in another were also observed. Further investigations revealed causative mutations in the exon (c.2166_2766del) and intron (c.4730-3 T > G) of the LRBA gene. These results may provide further elucidation of the clinical phenotypes and responsible genetic factors of LRBA deficiency.

Intrauterine IPEX

IPEX is one of the few Inborn Errors of Immunity that may manifest in the fetal period, and its intrauterine forms certainly represent the earliest human autoimmune diseases. Here, we review the clinical, histopathologic, and genetic findings from 21 individuals in 11 unrelated families, with nine different mutations, described as cases of intrauterine IPEX. Recurrent male fetal death (multigenerational in five families) due to hydrops in the midsemester of pregnancy was the commonest presentation (13/21). Noteworthy, in the affected families, there were only fetal- or perinatal-onset cases, with no affected individuals presenting milder forms with later-life manifestation. Most alive births were preterm (5/6). Skin desquamation and intrauterine growth restriction were observed in part of the cases. Fetal ultrasonography showed hyperechoic bowel or dilated bowel loops in the five cases with available imaging data. Histopathology showed multi-visceral infiltrates with T lymphocytes and other cells, including eosinophils, the pancreas being affected in most of the cases (11/21) and as early as at 18 weeks of gestational age. Regarding the nine FOXP3 mutations found in these cases, six determine protein truncation and three predictably impair protein function. Having found distinct presentations for the same FOXP3 mutation in different families, we resorted to the mouse system and showed that the scurfy mutation also shows divergent severity of phenotype and age of death in C57BL/6 and BALB/c backgrounds. We also reviewed age-of-onset data from other monogenic Tregopathies leading to IPEX-like phenotypes. In monogenic IPEX-like syndromes, the intrauterine onset was only observed in two kindreds with IL2RB mutations, with two stillbirths and two premature neonates who did not survive. In conclusion, intrauterine IPEX cases seem to constitute a particular IPEX subgroup, certainly with the most severe clinical presentation, although no strict mutation-phenotype correlations could be drawn for these cases.

Acute Cervical Longitudinally Extensive Transverse Myelitis in a Child With Lipopolysaccharide-Responsive-Beige-Like-Anchor-Protein (LRBA) Deficiency: A New Complication of a Rare Disease

Lipopolysaccharide responsive beige-like anchor protein (LRBA) deficiency is a primary immunodeficiency disorder (PID) that can cause a common variable immunodeficiency (CVID)-like disease. The typical features of the disease are autoimmunity, chronic diarrhea, and hypogammaglobulinemia. Neurological complications are also reported in patients affected by LRBA deficiency. We describe a 7-year old female with an acute cervical longitudinally extensive transverse myelitis (LETM) as a feature of LRBA deficiency. This is the first case of LETM associated with LRBA deficiency described in literature.

Long-term outcome of LRBA deficiency in 76 patients after various treatment modalities as evaluated by the immune deficiency and dysregulation activity (IDDA) score

BACKGROUND

Recent findings strongly support hematopoietic stem cell transplantation (HSCT) in patients with severe presentation of LPS-responsive beige-like anchor protein (LRBA) deficiency, but long-term follow-up and survival data beyond previous patient reports or meta-reviews are scarce for those patients who do not receive a transplant.

OBJECTIVE

This international retrospective study was conducted to elucidate the longitudinal clinical course of patients with LRBA deficiency who do and do not receive a transplant.

METHOD

We assessed disease burden and treatment responses with a specially developed immune deficiency and dysregulation activity score, reflecting the sum and severity of organ involvement and infections, days of hospitalization, supportive care requirements, and performance indices.

RESULTS

Of 76 patients with LRBA deficiency from 29 centers (median follow-up, 10 years; range, 1-52), 24 underwent HSCT from 2005 to 2019. The overall survival rate after HSCT (median follow-up, 20 months) was 70.8% (17 of 24 patients); all deaths were due to nonspecific, early, transplant-related mortality. Currently, 82.7% of patients who did not receive a transplant (43 of 52; age range, 3-69 years) are alive. Of 17 HSCT survivors, 7 are in complete remission and 5 are in good partial remission without treatment (together, 12 of 17 [70.6%]). In contrast, only 5 of 43 patients who did not receive a transplant (11.6%) are without immunosuppression. Immune deficiency and dysregulation activity scores were significantly lower in patients who survived HSCT than in those receiving conventional treatment (P = .005) or in patients who received abatacept or sirolimus as compared with other therapies, and in patients with residual LRBA expression. Higher disease burden, longer duration before HSCT, and lung involvement were associated with poor outcome.

CONCLUSION

The lifelong disease activity, implying a need for immunosuppression and risk of malignancy, must be weighed against the risks of HSCT.

Tesher M. Arthritis in children with LRBA deficiency - case report and literature review

BACKGROUND

Lipopolysaccharide (LPS)-responsive and beige like anchor (LRBA) deficiency is categorized as a subtype of common variable immune deficiency (CVID). A growing number of case reports and cohorts reveal a broad spectrum of clinical manifestations and variable phenotype expression, including immune dysregulation, enteropathy and recurrent infections. The association between rheumatic disease and CVID generally has been well established, arthritis has been less frequently reported and minimal data regarding its clinical features and characteristic in LRBA deficiency has been published. This case report and literature review evaluates the characteristics and features of arthritis in LRBA deficiency patients.

CASE PRESENTATION AND REVIEW RESULTS

Herein, we describe a unique case of LRBA deficiency first presented with poly articular arthritis. Alongside the report, a literature review focusing on LRBA deficiency, rheumatic disease and arthritis has been conducted. We reviewed 43 publications. Among these, 7 patients were identified with arthritis. Age of first presentation was six weeks to 3 years. Male to female ratio was 4/3. Two patients were diagnosed with polyarticular Juvenile idiopathic arthritis (JIA) and three with oligoarticular JIA. Each patient was found to have different genomic mutation. The treatment was diverse and included corticosteroids, cyclosporine, methotrexate, adalidumab and abatacept.

CONCLUSION

Joint involvement is variable in LRBA deficiency, hence it should always be kept in mind as a differential diagnosis for a patient with combination of juvenile arthritis and clinically atypical immune dysregulation and / or immunodeficiency.

Clinical, Immunologic, and Molecular Spectrum of Patients with LPS-Responsive Beige-Like Anchor Protein Deficiency: A Systematic Review

BACKGROUND

LPS-responsive beige-like anchor protein (LRBA) deficiency is a primary immunodeficiency and immune dysregulation syndrome caused by biallelic mutations in the LRBA gene. These mutations usually abrogate the protein expression of LRBA, leading to a broad spectrum of clinical phenotypes including autoimmunity, chronic diarrhea, hypogammaglobulinemia, and recurrent infections.

OBJECTIVE

Our aim was to systematically collect all studies reporting on the clinical manifestations, molecular and laboratory findings, and management of patients with LRBA deficiency.

METHODS

We searched in PubMed, Web of Science, and Scopus without any restrictions on study design and publication time. A total of 109 LRBA-deficient cases were identified from 45 eligible articles. For all patients, demographic information, clinical records, and immunologic and molecular data were collected.

RESULTS

Of the patients with LRBA deficiency, 93 had homozygous and 16 had compound heterozygous mutations in LRBA. The most common clinical manifestations were autoimmunity (82%), enteropathy (63%), splenomegaly (57%), and pneumonia (49%). Reduction in numbers of CD4⁺ T cells and regulatory T cells as well as IgG levels was recorded for 21.6%, 65.6%, and 54.2% of evaluated patients, respectively. B-cell subpopulation analysis revealed low numbers of switched-memory and increased numbers of CD21^low B cells in 73.5% and 77.8% of patients, respectively. Eighteen (16%) patients underwent hematopoietic stem cell transplantation due to the severity of complications and the outcomes improved in 13 of them.

CONCLUSIONS

Autoimmune disorders are the main clinical manifestations of LRBA deficiency. Therefore, LRBA deficiency should be included in the list of monogenic autoimmune diseases, and screening for LRBA mutations should be routinely performed for patients with these conditions.

The profile of IL-4, IL-5, IL-10 and GATA3 in patients with LRBA deficiency and CVID with no known monogenic disease: Association with disease severity

BACKGROUND

Common variable immunodeficiency (CVID) is the most common symptomatic form of primary immunodeficiency (PID). LPS-responsive beige-like anchor protein (LRBA) deficiency is an autosomal recessive disease characterized by a CVID-like phenotype. T cell abnormality was reported in patients with CVID and LRBA deficiency. The study's aim was to evaluate IL-4, IL-5, IL-10 and GATA3 expression in patients with LRBA deficiency and CVID with no known monogenic disease, and further evaluate its relevance with immunological futures and clinical complications of patients.

METHODS

The study population comprised patients with CVID, LRBA deficiency and age-sex matched healthy controls. Mutation analysis was done by whole exome sequencing in CVID patients to rule out monogenic PIDs. After CD4+ T cell stimulation with anti-CD3 and anti-CD28 monoclonal antibodies, gene expression of IL-4, IL-5, IL-10 and transcription factor GATA3 was evaluated by real-time polymerase chain reaction. The protein of mentioned cytokines was assessed by enzyme-linked immunosorbent assay.

RESULTS

The main clinical presentations of CVID patients were infections only and lymphoproliferations phenotypes, but in LRBA patients were autoimmune and enteropathy phenotype. The frequencies of CD4⁺ T cells were significantly reduced in LRBA and CVID patients. There were no statistically significant differences among GATA3, IL4, and IL5 gene expressions by CD4⁺ T cells of patients and controls, however, the IL10 expressions in CVID patients was significantly lower than in LRBA patients and HCs. As compared with HCs, CVID patients showed a prominent decrease in IL-4 and IL-10 production by CD4⁺ T cells.

CONCLUSIONS

Our findings demonstrated that patients with CVID and LRBA deficiency (even with severe infectious and inflammatory complications) have not imbalance in Th2 response, which is in parallel with lower frequency of allergy and asthma in these patients.

Primary immunodeficiency and autoimmunity: A comprehensive review

The primary immunodeficiency diseases (PIDs) include many genetic disorders that affect different components of the innate and adaptive responses. The number of distinct genetic PIDs has increased exponentially with improved methods of detection and advanced laboratory methodology. Patients with PIDs have an increased susceptibility to infectious diseases and non-infectious complications including allergies, malignancies and autoimmune diseases (ADs), the latter being the first manifestation of PIDs in several cases. There are two types of PIDS. Monogenic immunodeficiencies due to mutations in genes involved in immunological tolerance that increase the predisposition to develop autoimmunity including polyautoimmunity, and polygenic immunodeficiencies characterized by a heterogeneous clinical presentation that can be explained by a complex pathophysiology and which may have a multifactorial etiology. The high prevalence of ADs in PIDs demonstrates the intricate relationships between the mechanisms of these two conditions. Defects in central and peripheral tolerance, including mutations in AIRE and T regulatory cells respectively, are thought to be crucial in the development of ADs in these patients. In fact, pathology that leads to PID often also impacts the Treg/Th17 balance that may ease the appearance of a proinflammatory environment, increasing the odds for the development of autoimmunity. Furthermore, the influence of chronic and recurrent infections through molecular mimicry, bystander activation and super antigens activation are supposed to be pivotal for the development of autoimmunity. These multiple mechanisms are associated with diverse clinical subphenotypes that hinders an accurate diagnosis in clinical settings, and in some cases, may delay the selection of suitable pharmacological therapies. Herein, a comprehensively appraisal of the common mechanisms among these conditions, together with clinical pearls for treatment and diagnosis is presented.

G2-lymphocyte chromosomal radiosensitivity in patients with LPS responsive beige-like anchor protein (LRBA) deficiency

Lipopolysaccharide-responsive, beige-like anchor protein (LRBA) deficiency is an autosomal recessive primary immunodeficiency disease characterized by a CVID-like phenotype, particularly severe autoimmunity and inflammatory bowel disease. This study was undertaken to evaluate radiation sensitivity in 11 LRBA-deficient patients. Therefore, stimulated lymphocytes of the studied subjects were exposed to a low dose γ-radiation (100 cGy) in the G₂ phase of the cell cycle and chromosomal aberrations were scored. Lymphocytes of age-sex matched healthy individuals used in the same way as controls. Based on the G₂-assay, six (54.5%) of the patients had higher radiosensitivity score comparing to the healthy control group, forming the radiosensitive LRBA-deficient patients. This chromosomal radiosensitivity showed that these patients are predisposed to autoimmunity and/or malignancy, and should be protected from unnecessary diagnostic and therapeutic procedures using ionizing radiation and exposure to other DNA damaging agents.

Pulmonary Manifestations of Predominantly Antibody Deficiencies

Predominantly antibody deficiencies (PADs) are the most frequent forms of primary immunodeficiency diseases (PIDs). Commonly accompanied with complications involving several body systems, immunoglobulin substitution therapy along with prophylactic antibiotics remained the cornerstone of treatment for PADs and related complications. Patients with respiratory complications should be prescribed an appropriate therapy as soon as possible and have to be adhering to more and longer medical therapies. Recent studies identified a gap for screening protocols to monitor respiratory manifestations in patients with PADs. In the present chapter, the pulmonary manifestations of different PADs for each have been discussed. The chapter is mainly focused on X-linked agammaglobulinemia, common variable immunodeficiency, activated PI3K-δ syndrome, LRBA deficiency, CD19 complex deficiencies, CD20 deficiency, other monogenic defects associated with hypogammaglobulinemia, immunoglobulin class switch recombination deficiencies affecting B-cells, transient hypogammaglobulinemia of infancy, and selective IgA deficiency.

A role for Th1-like Th17 cells in the pathogenesis of inflammatory and autoimmune disorders

The T helper 17 (Th17) cells contain a dynamic subset of CD4+ T-cells that are able to develop into other different lineage subsets, including the Th1-like Th17 cells. These cells co-express retinoic acid-related orphan receptor gamma t (RORγt) and transcription factor T-box-expressed-in-T-cells (T-bet) and produce both interleukin (IL)-17 and interferon (IFN)-γ. Recent reports have shown that Th1-like Th17 cells play crucial roles in the pathogenesis of autoimmune diseases such as inflammatory bowel disease, multiple sclerosis and rheumatoid arthritis, as well as, some primary immunodeficiency with autoimmune features. Here, the actual mechanisms for Th17 cells plasticity to Th1-like Th17 cells are discussed and reviewed in association to the role that Th1-like Th17 cells have on inflammatory and autoimmune disorders.

Two male siblings with a novel LRBA mutation presenting with different findings of IPEX syndrome

Introduction

LPS-responsive beige-like anchor (LRBA) protein deficiency is a disease of immune dysregulation with autoimmunity affecting various systems.

Case Presentation

Two male siblings with a novel LRBA mutation had different primary findings at admission: the younger sibling had chronic early-onset diarrhoea and the elder one had autoimmune haemolytic anaemia. During long-term follow-up for IPEX phenotype, both developed hypogammaglobulinaemia, enteropathy and lung involvement. The patients partially responded to immunosuppressive therapies. A homozygous c.2496C>A, p.Cys832Ter (p.C832*) mutation in the LRBA gene causing a premature stop codon was detected. After molecular diagnosis, abatacept, as a target-specific molecule, was used with promising results.

Conclusion

LRBA deficiency is a recently defined defect, with variable presentations in different patients; a single, definitive treatment option is thus not yet available.

Fourth Update on the Iranian National Registry of Primary Immunodeficiencies: Integration of Molecular Diagnosis

BACKGROUND

The number of inherited diseases and the spectrum of clinical manifestations of primary immunodeficiency disorders (PIDs) are ever-expanding. Molecular diagnosis using genomic approaches should be performed for all PID patients since it provides a resource to improve the management and to estimate the prognosis of patients with these rare immune disorders.

METHOD

The current update of Iranian PID registry (IPIDR) contains the clinical phenotype of newly registered patients during last 5 years (2013-2018) and the result of molecular diagnosis in patients enrolled for targeted and next-generation sequencing.

RESULTS

Considering the newly diagnosed patients (n = 1395), the total number of registered PID patients reached 3056 (1852 male and 1204 female) from 31 medical centers. The predominantly antibody deficiency was the most common subcategory of PID (29.5%). The putative causative genetic defect was identified in 1014 patients (33.1%) and an autosomal recessive pattern was found in 79.3% of these patients. Among the genetically different categories of PID patients, the diagnostic rate was highest in defects in immune dysregulation and lowest in predominantly antibody deficiencies and mutations in the MEFV gene were the most frequent genetic disorder in our cohort.

CONCLUSIONS

During a 20-year registration of Iranian PID patients, significant changes have been observed by increasing the awareness of the medical community, national PID network establishment, improving therapeutic facilities, and recently by inclusion of the molecular diagnosis. The current collective study of PID phenotypes and genotypes provides a major source for ethnic surveillance, newborn screening, and genetic consultation for prenatal and preimplantation genetic diagnosis.

Monogenic polyautoimmunity in primary immunodeficiency diseases

Primary immunodeficiency diseases (PIDs) consist of a large group of genetic disorders that affect distinct components of the immune system. PID patients are susceptible to infection and non-infectious complications, particularly autoimmunity. A specific group of monogenic PIDs are due to mutations in genes that are critical for the regulation of immunological tolerance and immune responses. This group of monogenic PIDs is at high risk of developing polyautoimmunity (i.e., the presence of more than one autoimmune disease in a single patient) because of their impaired immunity. In this review, we discuss the mechanisms of autoimmunity in PIDs and the characteristics of polyautoimmunity in the following PIDs: IPEX; monogenic IPEX-like syndrome; LRBA deficiency; CTLA4 deficiency; APECED; ALPS; and PKCδ deficiency.

Respiratory manifestations in LPS-responsive beige-like anchor (LRBA) protein-deficient patients

Lipopolysaccharide (LPS)-responsive beige-like anchor (LRBA) protein deficiency is a rare syndrome of primary immune deficiency and immune dysregulation. In this study, we sought to summarize our experience with respiratory manifestations in LRBA-deficient patients. We conducted a retrospective analysis of the medical records of LRBA-deficient patients treated at Hadassah-Hebrew University Medical Center, Jerusalem, Israel. Data retrieved included pulmonary workup, disease course, treatment, and outcome. Ten patients were included. Mean age at presentation of LRBA deficiency-related symptoms was 4.65 years (range 3 months-14 years). Respiratory symptoms were noted in six patients and consisted of chronic cough. Computed tomography revealed consolidation in five patients, atelectasis and bronchiectasis in two patients each, and diffuse interstitial lung disease in two additional patients. Respiratory tract cultures yielded a bacterial pathogen in five patients. Seven patients required active therapy: intravenous immunoglobulins (six patients), immunosuppressive drugs (five patients), and one was successfully treated with abatacept. Two patients underwent successful bone marrow transplantation. Mean follow-up period was 4.5 (range 0.4-14.4) years. On their latest examination, seven patients had no respiratory symptoms.

CONCLUSION

Pulmonary manifestations are common in LRBA deficiency. Respiratory characteristics in LRBA-deficient patients should be investigated, monitored, and treated from the time of diagnosis. What is Known: • Lipopolysaccharide-responsive beige-like anchor (LRBA) deficiency is a syndrome of primary immune deficiency and immune dysregulation. • Studies concerning the pulmonary characteristics of LRBA-deficient patients are lacking. What is New: • Respiratory manifestations include infections, bronchiectasis, interstitial lung disease, thoracic lymphadenopathy, and clubbing. • Awareness to pulmonary morbidity in LRBA-deficient patients and involvement of a pulmonologist in the workup and clinical decision-making is important. • Respiratory characteristics in LRBA-deficient patients should be investigated, monitored, and treated from a young age.

Clinical implications of systematic phenotyping and exome sequencing in patients with primary antibody deficiency

PURPOSE

The etiology of 80% of patients with primary antibody deficiency (PAD), the second most common type of human immune system disorder after human immunodeficiency virus infection, is yet unknown.

METHODS

Clinical/immunological phenotyping and exome sequencing of a cohort of 126 PAD patients (55.5% male, 95.2% childhood onset) born to predominantly consanguineous parents (82.5%) with unknown genetic defects were performed. The American College of Medical Genetics and Genomics criteria were used for validation of pathogenicity of the variants.

RESULTS

This genetic approach and subsequent immunological investigations identified potential disease-causing variants in 86 patients (68.2%); however, 27 of these patients (31.4%) carried autosomal dominant (24.4%) and X-linked (7%) gene defects. This genetic approach led to the identification of new phenotypes in 19 known genes (38 patients) and the discovery of a new genetic defect (CD70 pathogenic variants in 2 patients). Medical implications of a definite genetic diagnosis were reported in ~50% of the patients.

CONCLUSION

Due to misclassification of the conventional approach for targeted sequencing, employing next-generation sequencing as a preliminary step of molecular diagnostic approach to patients with PAD is crucial for management and treatment of the patients and their family members.