Cytomegalovirus drives Vδ1+ γδ T cell expansion and clonality in common variable immunodeficiency.

The function and phenotype of γδ T cells in the context of common variable immunodeficiency (CVID) has not been explored. CVID is a primary immunodeficiency disorder characterized by impaired antibody responses resulting in increased susceptibility to infections. γδ T cells are a subset of unconventional T cells that play crucial roles in host defence against infections. In this study, we aim to determine the roles and functions of γδ T cells in CVID. We observe a higher frequency of Vδ1+ γδ T cells compared to healthy controls, particularly in older patients. We also find a higher proportion of effector-memory Vδ1+ γδ T cells and a more clonal T cell receptor (TCR) repertoire in CVID. The most significant driver of the Vδ1+ γδ T cell expansion and phenotype in CVID patients is persistent cytomegalovirus (CMV) viremia. These findings provide valuable insights into γδ T cell biology and their contribution to immune defence in CVID.

A single-center experience of COVID-19 infection in patients with primary immunodeficiency.

Background: Reported outcomes in patients with primary immunodeficiency (PID) infected by coronavirus disease 2019 (COVID-19) have been variable owing to a combination of viral strain heterogeneity, differences in patient populations and health systems, and local availability of vaccination and specific COVID-19 therapies. There are few reports on the experience of Australian patients with PID during the pandemic. Objectives: In this retrospective study, we describe the baseline characteristics and short-term outcomes of patients with PID who were infected by COVID-19 and known to the Royal Melbourne Hospital, a major tertiary center in Victoria, Australia. Methods: Between April 2021 and April 2022, a total of 31 of 138 patients with PID were affected by COVID-19. More than half of them had 3 vaccine doses at the time of infection (which at the time was considered being fully vaccinated) and received COVID-19-targeted treatment. Results: All of the infected patients had ambulatory disease, with no cases of morbidity or mortality. In line with the current literature, the PID subtypes described did not appear to independently predict worse outcomes. Conclusions: Some protective factors include this cohort's relatively younger average age and its high uptake of vaccination and COVID-19 therapies.

A common human MLKL polymorphism confers resistance to negative regulation by phosphorylation.

Across the globe, 2-3% of humans carry the p.Ser132Pro single nucleotide polymorphism in MLKL, the terminal effector protein of the inflammatory form of programmed cell death, necroptosis. Here we show that this substitution confers a gain in necroptotic function in human cells, with more rapid accumulation of activated MLKLS132P in biological membranes and MLKLS132P overriding pharmacological and endogenous inhibition of MLKL. In mouse cells, the equivalent Mlkl S131P mutation confers a gene dosage dependent reduction in sensitivity to TNF-induced necroptosis in both hematopoietic and non-hematopoietic cells, but enhanced sensitivity to IFN-ß induced death in non-hematopoietic cells. In vivo, MlklS131P homozygosity reduces the capacity to clear Salmonella from major organs and retards recovery of hematopoietic stem cells. Thus, by dysregulating necroptosis, the S131P substitution impairs the return to homeostasis after systemic challenge. Present day carriers of the MLKL S132P polymorphism may be the key to understanding how MLKL and necroptosis modulate the progression of complex polygenic human disease.

A multicenter chart review of patient characteristics, treatment, and outcomes in hereditary angioedema: unmet need for more effective long-term prophylaxis.

BACKGROUND: Hereditary angioedema (HAE) is a rare disease characterized by unpredictable, recurring subcutaneous or submucosal swelling. Without effective therapy, HAE can negatively impact patients' quality of life. Management of HAE includes on-demand treatment of attacks and short- and long-term prophylaxis (LTP) to prevent attacks. Newer therapies may be more tolerable and effective in managing HAE; however, therapies such as androgens are still widely used in some countries owing to their relative ease of access and adequate disease control for some patients. This study evaluated the characteristics, treatment patterns, clinical outcomes, and healthcare resource utilization of a multinational cohort of patients with HAE, with a focus on understanding reasons for recommending or discontinuing available therapies. METHODS: A retrospective chart review was conducted at 12 centers in six countries and included data from patients with HAE type 1 or 2 who were ≥ 12 years of age at their first clinical visit. The relationship between LTP use and attack rates was evaluated using a multivariable Poisson regression model. Data were collected between March 2018 and July 2019. RESULTS: Data from 225 patients were collected (62.7% female, 86.2% White, 90.2% type 1); 64.4% of patients had their first HAE-related visit to the center prior to or during 2014. Treatment patterns varied between countries. Overall, 85.8% of patients were prescribed on-demand treatment and 53.8% were prescribed LTP, most commonly the androgen danazol (53.7% of patients who used LTP). Plasma-derived C1 inhibitor (Cinryze®) was used by 29.8% of patients for LTP. Patients who received LTP had a significantly lower rate of HAE attacks than patients who did not receive any LTP (incidence rate ratio (95% confidence interval) 0.90 (0.84-0.96)). Androgens were the most commonly discontinued therapy (51.3%), with low tolerability cited as the most frequent reason for discontinuation (50.0%). CONCLUSIONS: Overall, findings from this study support the use of LTP in the prevention of HAE attacks; a lower rate of attacks was observed with LTP compared with no LTP. However, the type of LTP used varied between countries, with tolerability and accessibility to specific treatments playing important roles in management decision-making.

Victorian Specialist Immunisation Services (VicSIS) - bolstering adult clinics for COVID-19 vaccines.

The Victorian Specialist Immunization Services (VicSIS) was established in Victoria, Australia, in February 2021, aiming to enhance vaccine safety services for Coronavirus disease (COVID-19) vaccines. VicSIS supports practitioners and patients with complex vaccine safety questions, including those who experience adverse events following immunization (AEFI) after COVID-19 vaccines. VicSIS provides individual vaccination recommendations, allergy testing, vaccine challenges, and vaccination under supervision. VicSIS initially comprised of eight adult COVID-19 specialist vaccination clinics, subsequently, expanding to better support pediatric patients as the Australian vaccine roll-out extended to adolescents and children. Since their establishment to September 2021, the inaugural VicSIS clinics received a total of 26,401 referrals and reviewed 6,079 patients. Consults were initially predominantly for pre-vaccination reviews, later predominantly becoming post-vaccination AEFI reviews as the program progressed. Regardless of the type of consult, the most common consult outcome was a recommendation for routine vaccination (73% and 55% of consult outcomes respectively). VicSIS is an integral component of the COVID-19 vaccination program and supports confidence in COVID-19 vaccine safety by providing consistent advice across the state. VicSIS aims to strengthen the health system through the pandemic, bolstering specialist immunization services beyond COVID-19 vaccines, including training the next generation of vaccinology experts.

Case Report: Cytomegalovirus Disease Is an Under-Recognized Contributor to Morbidity and Mortality in Common Variable Immunodeficiency.

BACKGROUND: Common Variable Immunodeficiency (CVID) is classified as a 'Predominantly Antibody Deficiency' (PAD), but there is emerging evidence of cellular immunodeficiency in a subset of patients. This evidence includes CVID patients diagnosed with cytomegalovirus (CMV) infection, a hallmark of 'combined immunodeficiency'. CMV infection also has the potential to drive immune dysregulation contributing to significant morbidity and mortality in CVID. We aim to determine the extent of cellular immune dysfunction in CVID patients, and whether this correlates with CMV infection status. METHODS: We conducted a single-center retrospective cohort study of individuals with CVID at the Royal Melbourne Hospital, and identified patients with and without CMV disease or viraemia. We then isolated T-cells from patient and healthy donor blood samples and examined T-cell proliferation and function. RESULTS: Six patients (7.6%, 6/79) had either CMV disease (pneumonitis or gastrointestinal disease), or symptomatic CMV viraemia. A high mortality rate in the cohort of patients with CVID and CMV disease was observed, with 4 deaths in the period of analysis (66.6%, 4/6). Individuals with CMV infection showed reduced T-cell division in response to T-cell receptor (TCR) stimulation when compared with CMV-negative patients. DISCUSSION: This study demonstrates the morbidity and mortality associated with CMV in CVID, and highlights the need for focused interventions for patients with CVID at risk of CMV disease.

Cytomegalovirus in primary immunodeficiency.

PURPOSE OF REVIEW: Cytomegalovirus (CMV) infection and disease are well described in the setting of secondary immunodeficiency. Less is known about CMV in the context of primary immunodeficiencies (PIDs), where inborn errors in one or more arms of the immune system result in variable degrees of CMV susceptibility. RECENT FINDINGS: PID presents unique challenges in the diagnosis and management of CMV disease. The clinical presentation of CMV in PID is often severe, accelerated by underlying immune dysregulation and iatrogenic immunosuppression. Here we describe the clinical significance of CMV infection in PID, the key components of immune defence against CMV and how these are affected in specific PIDs. CMV disease is under-recognized as a complication of common variable immunodeficiency (CVID). High rates of CMV end-organ disease, mortality, development of CMV resistance and prolonged antiviral use have been observed in individuals with CVID. SUMMARY: We recommend that clinicians tailor their approach to the individual based on their underlying immune deficit and maintain a high index of suspicion and low threshold for treatment. More research is required to improve stratification of CMV risk in PID, develop new diagnostic tools and manage end-organ disease in this cohort.

Newborn Screening for Presymptomatic Diagnosis of Complement and Phagocyte Deficiencies.

The clinical outcomes of primary immunodeficiencies (PIDs) are greatly improved by accurate diagnosis early in life. However, it is not common to consider PIDs before the manifestation of severe clinical symptoms. Including PIDs in the nation-wide newborn screening programs will potentially improve survival and provide better disease management and preventive care in PID patients. This calls for the detection of disease biomarkers in blood and the use of dried blood spot samples, which is a part of routine newborn screening programs worldwide. Here, we developed a newborn screening method based on multiplex protein profiling for parallel diagnosis of 22 innate immunodeficiencies affecting the complement system and respiratory burst function in phagocytosis. The proposed method uses a small fraction of eluted blood from dried blood spots and is applicable for population-scale performance. The diagnosis method is validated through a retrospective screening of immunodeficient patient samples. This diagnostic approach can pave the way for an earlier, more comprehensive and accurate diagnosis of complement and phagocytic disorders, which ultimately lead to a healthy and active life for the PID patients.

Loss-of-Function in SMAD4 Might Not Be Critical for Human Natural Killer Cell Responsiveness to TGF-ß.

We characterized the NK cell phenotype and function in three family members with Hereditary Hemorrhagic Telangiectasia (HHT) due to heterozygous SMAD4 mutations. Loss-of-function mutation in this gene did not induce developmental effects to alter CD56bright or CD56dim NK cell subset proportions in peripheral blood; and did not result in major differences in either their IL-15-induced proliferation, or their cytokine secretion response to TGF-ß1. These data suggest that SMAD4 plays a redundant role in downstream TGF-ß signaling in NK cells.

Unprecedented New Crystalline Forms of SnSe in Narrow to Medium Diameter Carbon Nanotubes.

We report the observation of four unprecedented new crystalline forms of SnSe, obtained as a result of encapsulation in narrow to medium diameter single-walled carbon nanotubes. Aberration-corrected scanning transmission electron microscopy at 80 kV revealed linear, zigzag, helical (i.e., 2 × 1) atomic chains and a new form of encapsulated SnSe. This new form is apparently isostructural to free-standing MoS, MoSe, and WSe extreme nanowires etched from the corresponding monolayer dichalcogenides and also recently observed encapsulated MoTe. A structural model has been attained from annular dark-field (ADF) images. The experimental imaging agrees well with image simulations produced from models anticipated for the new structural forms.

Fatal Enteroviral Encephalitis in a Patient with Common Variable Immunodeficiency Harbouring a Novel Mutation in NFKB2.

Common variable immunodeficiency is the most prevalent of the primary immunodeficiency diseases, yet its pathogenesis is largely poorly understood. Of the cases that are monogenic, many arise due to pathogenic variants in NFKB1 and NFKB2. Here, we report enteroviral encephalomyelitis as the cause of a fatal neurodegenerative condition in a patient with a novel heterozygous mutation in NFKB2 (c.2543insG, p.P850Sfs36*) that disrupts non-canonical NF-κB signaling. Investigations of primary and secondary lymphoid tissue demonstrated a complete absence of B cells and germinal centers. Despite multiple negative viral PCR testing of cerebrospinal fluid during her disease progression, post-mortem analysis of cerebral tissue revealed a chronic lymphocytic meningoencephalitis, in the presence of Cocksackie A16 virus, as the cause of death. The clinical features, and progression of disease reported here, demonstrate divergent clinical and immunological phenotypes of individuals within a single family. This is the first reported case of fatal enteroviral encephalomyelitis in a patient with NF-κB2 deficiency and mandates a low threshold for early brain biopsy and the administration of increased immunoglobulin replacement in any patient with a defect in this pathway and deterioration of neurological status.

Pitfalls of immunotherapy: lessons from a patient with CTLA-4 haploinsufficiency.

BACKGROUND: Daclizumab is a humanized monoclonal antibody that blocks CD25, the high affinity alpha subunit of the interleukin-2 receptor. Daclizumab therapy targets T regulatory cell and activated effector T cell proliferation to suppress autoimmune disease activity, in inflammatory conditions like relapsing and remitting multiple sclerosis. Here, we present the first report of agranulocytosis with daclizumab therapy in a patient with relapsing and remitting multiple sclerosis. CASE PRESENTATION: Our patient was a 24-year-old Australian female with a clinical history of atopy, lymphocytic enteritis complicated by B12 deficiency, relapsing and remitting multiple sclerosis, recurrent lower respiratory tract infections, vulval/cervical intraepithelial neoplasia and melanoma. She was commenced on daclizumab therapy after failing several lines of treatment for relapsing and remitting multiple sclerosis. During a hospital admission for lymphocytic enteritis, she was incidentally diagnosed with combined immunodeficiency with hypogammaglobulinaemia and declined proposed regular intravenous immunoglobulin infusions. Following six months of daclizumab therapy, our patient presented to hospital with febrile neutropenia. No clear infective cause was found, despite numerous investigations. However, bone marrow biopsy revealed agranulocytosis with an apparent maturation block at the myeloblasts stage. Neustrophil recovery occurred following cessation of daclizumab and the initiation of T cell immunosuppressive agents including systemic corticosteroids and methotrexate. The patient was further investigated for combined immunodeficiency and whole exome sequencing revealed a novel heterozygous missense variant in cytotoxic T lymphocyte antigen 4 (CTLA4), leading to a diagnosis of CTLA-4 haploinsufficiency with autoimmune infiltration (CHAI). CONCLUSION: This case demonstrates that autoimmune disease may be the presenting feature of primary immunodeficiency and should be appropriately investigated prior to the commencement of immunotherapy. Genetic clarification of underlying primary immunodeficiency may provide critical clinical information that alters the safety of the proposed treatment strategy.

The Rare Anaphylaxis-Associated FcγRIIa3 Exhibits Distinct Characteristics From the Canonical FcγRIIa1.

FcγRIIa is an activating FcγR, unique to humans and non-human primates. It induces antibody-dependent proinflammatory responses and exists predominantly as FcγRIIa1. A unique splice variant, we designated FcγRIIa3, has been reported to be associated with anaphylactic reactions to intravenous immunoglobulins (IVIg) therapy. We aim to define the functional consequences of this FcγRIIa variant associated with adverse responses to IVIg therapy and evaluate the frequency of associated SNPs. FcγRIIa forms from macaque and human PBMCs were investigated for IgG-subclass specificity, biochemistry, membrane localization, and functional activity. Disease-associated SNPs were analyzed by sequencing genomic DNA from 224 individuals with immunodeficiency or autoimmune disease. FcγRIIa3 was identified in macaque and human PBMC. The FcγRIIa3 is distinguished from the canonical FcγRIIa1 by a unique 19-amino acid cytoplasmic insertion and these two FcγRIIa forms responded distinctly to antibody ligation. Whereas FcγRIIa1 was rapidly internalized, FcγRIIa3 was retained longer at the membrane, inducing greater calcium mobilization and cell degranulation. Four FCGR2A SNPs were identified including the previously reported intronic SNP associated with anaphylaxis, but in only 1 of 224 individuals. The unique cytoplasmic element of FcγRIIa3 delays internalization and is associated with enhanced cellular activation. The frequency of the immunodeficiency-associated SNP varies between disease populations but interestingly occurred at a lower frequency than previously reported. None-the-less enhanced FcγRIIa3 function may promote a proinflammatory environment and predispose to pathological inflammatory responses.

Delayed Diagnosis and Complications of Predominantly Antibody Deficiencies in a Cohort of Australian Adults.

Background: Predominantly antibody deficiencies (PADs) are the most common type of primary immunodeficiency in adults. PADs frequently pass undetected leading to delayed diagnosis, delayed treatment, and the potential for end-organ damage including bronchiectasis. In addition, PADs are frequently accompanied by comorbid autoimmune disease, and an increased risk of malignancy. Objectives: To characterize the diagnostic and clinical features of adult PAD patients in Victoria, Australia. Methods: We identified adult patients receiving, or having previously received immunoglobulin replacement therapy for a PAD at four hospitals in metropolitan Melbourne, and retrospectively characterized their clinical and diagnostic features. Results: 179 patients from The Royal Melbourne, Alfred and Austin Hospitals, and Monash Medical Centre were included in the study with a median age of 49.7 years (range: 16-87 years), of whom 98 (54.7%) were female. The majority of patients (116; 64.8%) met diagnostic criteria for common variable immunodeficiency (CVID), and 21 (11.7%) were diagnosed with X-linked agammaglobulinemia (XLA). Unclassified hypogammaglobulinemia (HGG) was described in 22 patients (12.3%), IgG subclass deficiency (IGSCD) in 12 (6.7%), and specific antibody deficiency (SpAD) in 4 individuals (2.2%). The remaining four patients had a diagnosis of Good syndrome (thymoma with immunodeficiency). There was no significant difference between the age at diagnosis of the disorders, with the exception of XLA, with a median age at diagnosis of less than 1 year. The median age of reported symptom onset was 20 years for those with a diagnosis of CVID, with a median age at diagnosis of 35 years. CVID patients experienced significantly more non-infectious complications, such as autoimmune cytopenias and lymphoproliferative disease, than the other antibody deficiency disorders. The presence of non-infectious complications was associated with significantly reduced survival in the cohort. Conclusion: Our data are largely consistent with the experience of other centers internationally, with clear areas for improvement, including reducing diagnostic delay for patients with PADs. It is likely that these challenges will be in part overcome by continued advances in implementation of genomic sequencing for diagnosis of PADs, and with that opportunities for targeted treatment of non-infectious complications.

Review: Diagnosing Common Variable Immunodeficiency Disorder in the Era of Genome Sequencing.

Common variable immunodeficiency disorders (CVID) are an enigmatic group of often heritable conditions, which may manifest for the first time in early childhood or as late as the eighth decade of life. In the last 5 years, next generation sequencing (NGS) has revolutionised identification of genetic disorders. However, despite the best efforts of researchers around the globe, CVID conditions have been slow to yield their molecular secrets. We have previously described the many clinical advantages of identifying the genetic basis of primary immunodeficiency disorders (PIDs). In a minority of CVID patients, monogenic defects have now been identified. If a causative mutation is identified, these conditions are reclassified as CVID-like disorders. Here we discuss recent advances in the genetics of CVID and discuss how NGS can be optimally deployed to identify the causal mutations responsible for the protean clinical manifestations of these conditions. Diagnostic criteria such as the Ameratunga et al. criteria will continue to play an important role in patient management as well as case selection and sequencing strategy design until the genetic conundrum of CVID is solved.

Epistatic interactions between mutations of TACI (TNFRSF13B) and TCF3 result in a severe primary immunodeficiency disorder and systemic lupus erythematosus.

Common variable immunodeficiency disorders (CVID) are a group of primary immunodeficiencies where monogenetic causes account for only a fraction of cases. On this evidence, CVID is potentially polygenic and epistatic although there are, as yet, no examples to support this hypothesis. We have identified a non-consanguineous family, who carry the C104R (c.310T>C) mutation of the Transmembrane Activator Calcium-modulator and cyclophilin ligand Interactor (TACI, TNFRSF13B) gene. Variants in TNFRSF13B/TACI are identified in up to 10% of CVID patients, and are associated with, but not solely causative of CVID. The proband is heterozygous for the TNFRSF13B/TACI C104R mutation and meets the Ameratunga et al. diagnostic criteria for CVID and the American College of Rheumatology criteria for systemic lupus erythematosus (SLE). Her son has type 1 diabetes, arthritis, reduced IgG levels and IgA deficiency, but has not inherited the TNFRSF13B/TACI mutation. Her brother, homozygous for the TNFRSF13B/TACI mutation, is in good health despite profound hypogammaglobulinemia and mild cytopenias. We hypothesised that a second unidentified mutation contributed to the symptomatic phenotype of the proband and her son. Whole-exome sequencing of the family revealed a de novo nonsense mutation (T168fsX191) in the Transcription Factor 3 (TCF3) gene encoding the E2A transcription factors, present only in the proband and her son. We demonstrate mutations of TNFRSF13B/TACI impair immunoglobulin isotype switching and antibody production predominantly via T-cell-independent signalling, while mutations of TCF3 impair both T-cell-dependent and -independent pathways of B-cell activation and differentiation. We conclude that epistatic interactions between mutations of the TNFRSF13B/TACI and TCF3 signalling networks lead to the severe CVID-like disorder and SLE in the proband.

Clinical Implications of Digenic Inheritance and Epistasis in Primary Immunodeficiency Disorders.

The existence of epistasis in humans was first predicted by Bateson in 1909. Epistasis describes the non-linear, synergistic interaction of two or more genetic loci, which can substantially modify disease severity or result in entirely new phenotypes. The concept has remained controversial in human genetics because of the lack of well-characterized examples. In humans, it is only possible to demonstrate epistasis if two or more genes are mutated. In most cases of epistasis, the mutated gene products are likely to be constituents of the same physiological pathway leading to severe disruption of a cellular function such as antibody production. We have recently described a digenic family, who carry mutations of TNFRSF13B/TACI as well as TCF3 genes. Both genes lie in tandem along the immunoglobulin isotype switching and secretion pathway. We have shown they interact in an epistatic way causing severe immunodeficiency and autoimmunity in the digenic proband. With the advent of next generation sequencing, it is likely other families with digenic inheritance will be identified. Since digenic inheritance does not always cause epistasis, we propose an epistasis index which may help quantify the effects of the two mutations. We also discuss the clinical implications of digenic inheritance and epistasis in humans with primary immunodeficiency disorders.