Challenges for gene editing in common variable immunodeficiency disorders: Current and future prospects.

The original CRISPR Cas9 gene editing system and subsequent innovations offers unprecedented opportunities to correct severe genetic defects including those causing Primary Immunodeficiencies (PIDs). Common Variable Immunodeficiency Disorders (CVID) are the most frequent symptomatic PID in adults and children. Unlike many other PIDs, patients meeting CVID criteria do not have a definable genetic defect and cannot be considered to have an inborn error of immunity (IEI). Patients with a CVID phenotype carrying a causative mutation are deemed to have a CVID-like disorder consequent to an IEI. Patients from consanguineous families often have highly penetrant early-onset autosomal recessive forms of CVID-like disorders. Individuals from non-consanguineous families may have autosomal dominant CVID-like disorders with variable penetrance and expressivity. This essay explores the potential clinical utility as well as the current limitations and risks of gene editing including collateral genotoxicity. In the immediate future the main application of this technology is likely to be the in vitro investigation of epigenetic and polygenic mechanisms, which are likely to underlie many cases of CVID and CVID-like disorders. In the longer-term, the CRISPR Cas9 system and other gene-based therapies could be utilized to treat CVID-like disorders, where the underlying IEI is known.

Soluble wild-type ACE2 molecules inhibit newer SARS-CoV-2 variants and are a potential antiviral strategy to mitigate disease severity in COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease of 2019 (COVID-19), has caused havoc around the world. While several COVID-19 vaccines and drugs have been authorized for use, these antiviral drugs remain beyond the reach of most low- and middle-income countries. Rapid viral evolution is reducing the efficacy of vaccines and monoclonal antibodies and contributing to the deaths of some fully vaccinated persons. Others with normal immunity may have chosen not to be vaccinated and remain at risk if they contract the infection. Vaccines may not protect some immunodeficient patients from SARS-CoV-2, who are also at increased risk of chronic COVID-19 infection, a dangerous stalemate between the virus and a suboptimal immune response. Intra-host viral evolution could rapidly lead to the selection and dominance of vaccine and monoclonal antibody-resistant clades of SARS-CoV-2. There is thus an urgent need to develop new treatments for COVID-19. The NZACE2-Patari project, comprising modified soluble angiotensin-converting enzyme 2 (ACE2) molecules, seeks to intercept and block SARS-CoV-2 infection of the respiratory mucosa. In vitro data presented here show that soluble wild-type ACE2 molecules retain the ability to effectively block the Spike (S) glycoprotein of SARS-CoV-2 variants including the ancestral Wuhan, delta (B.1.617.2) and omicron (B.1.1.529) strains. This therapeutic strategy may prove effective if implemented early during the nasal phase of the infection and may act synergistically with other antiviral drugs such as Paxlovid to further mitigate disease severity.

First Identified Case of Fatal Fulminant Necrotizing Eosinophilic Myocarditis Following the Initial Dose of the Pfizer-BioNTech mRNA COVID-19 Vaccine (BNT162b2, Comirnaty): an Extremely Rare Idiosyncratic Hypersensitivity Reaction.

RATIONALE: Transient myopericarditis has been recognised as an uncommon and usually mild adverse event predominantly linked to mRNA-based COVID-19 vaccines. These have mostly occurred in young males after the second dose of mRNA COVID-19 vaccines. OBJECTIVES: Fulminant necrotising eosinophilic myocarditis triggered by a variety of drugs or vaccines is an extremely rare hypersensitivity reaction carrying a substantial mortality risk. Early recognition of this medical emergency may facilitate urgent hospital admission for investigation and treatment. Timely intervention can lead to complete cardiac recovery, but the non-specific clinical features and rarity make early diagnosis challenging. FINDINGS: The clinical and pathological observations from a case of fatal fulminant necrotising myocarditis in a 57-year-old woman, following the first dose of the Pfizer-BioNTech vaccine, are described. Other causes have been discounted with reasonable certainty. CONCLUSION: These extremely rare vaccine-related adverse events are much less common than the risk of myocarditis and other lethal complications from COVID-19 infection. The benefits of vaccination far exceed the risks of COVID-19 infection.

Droplet digital PCR for identifying copy number variations in patients with primary immunodeficiency disorders.

Primary immunodeficiency disorders comprise a rare group of mostly monogenic disorders caused by inborn errors of immunity. The majority can be identified by either Sanger sequencing or next generation sequencing. Some disorders result from large insertions or deletions leading to copy number variations (CNVs). Sanger sequencing may not identify these mutations. Here we present droplet digital PCR as an alternative cost-effective diagnostic method to identify CNV in these genes. The data from patients with large deletions of NFKB1, SERPING1, and SH2D1A are presented.

Characterization of the clinical and immunologic phenotype and management of 157 individuals with 56 distinct heterozygous NFKB1 mutations.

BACKGROUND: An increasing number of NFKB1 variants are being identified in patients with heterogeneous immunologic phenotypes. OBJECTIVE: To characterize the clinical and cellular phenotype as well as the management of patients with heterozygous NFKB1 mutations. METHODS: In a worldwide collaborative effort, we evaluated 231 individuals harboring 105 distinct heterozygous NFKB1 variants. To provide evidence for pathogenicity, each variant was assessed in silico; in addition, 32 variants were assessed by functional in vitro testing of nuclear factor of kappa light polypeptide gene enhancer in B cells (NF-κB) signaling. RESULTS: We classified 56 of the 105 distinct NFKB1 variants in 157 individuals from 68 unrelated families as pathogenic. Incomplete clinical penetrance (70%) and age-dependent severity of NFKB1-related phenotypes were observed. The phenotype included hypogammaglobulinemia (88.9%), reduced switched memory B cells (60.3%), and respiratory (83%) and gastrointestinal (28.6%) infections, thus characterizing the disorder as primary immunodeficiency. However, the high frequency of autoimmunity (57.4%), lymphoproliferation (52.4%), noninfectious enteropathy (23.1%), opportunistic infections (15.7%), autoinflammation (29.6%), and malignancy (16.8%) identified NF-κB1-related disease as an inborn error of immunity with immune dysregulation, rather than a mere primary immunodeficiency. Current treatment includes immunoglobulin replacement and immunosuppressive agents. CONCLUSIONS: We present a comprehensive clinical overview of the NF-κB1-related phenotype, which includes immunodeficiency, autoimmunity, autoinflammation, and cancer. Because of its multisystem involvement, clinicians from each and every medical discipline need to be made aware of this autosomal-dominant disease. Hematopoietic stem cell transplantation and NF-κB1 pathway-targeted therapeutic strategies should be considered in the future.

Haploinsufficiency of the NF-κB1 Subunit p50 in Common Variable Immunodeficiency.

Common variable immunodeficiency (CVID), characterized by recurrent infections, is the most prevalent symptomatic antibody deficiency. In ∼90% of CVID-affected individuals, no genetic cause of the disease has been identified. In a Dutch-Australian CVID-affected family, we identified a NFKB1 heterozygous splice-donor-site mutation (c.730+4A>G), causing in-frame skipping of exon 8. NFKB1 encodes the transcription-factor precursor p105, which is processed to p50 (canonical NF-κB pathway). The altered protein bearing an internal deletion (p.Asp191_Lys244delinsGlu; p105ΔEx8) is degraded, but is not processed to p50ΔEx8. Altered NF-κB1 proteins were also undetectable in a German CVID-affected family with a heterozygous in-frame exon 9 skipping mutation (c.835+2T>G) and in a CVID-affected family from New Zealand with a heterozygous frameshift mutation (c.465dupA) in exon 7. Given that residual p105 and p50­translated from the non-mutated alleles­were normal, and altered p50 proteins were absent, we conclude that the CVID phenotype in these families is caused by NF-κB1 p50 haploinsufficiency.

Prospective Evaluation of the ESPGHAN Guidelines for Diagnosis of Celiac Disease in New Zealand Children.

OBJECTIVE: The 2012 European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) guideline for diagnosis of celiac disease (CD) questioned the requirement for intestinal biopsy to confirm the diagnosis. The guideline recommends that in symptomatic patients with consistent human leukocyte antigen (HLA) subtypes, the diagnostic accuracy of strongly positive serology is sufficient to confirm the diagnosis. We prospectively assessed these guidelines in a "real-life" clinical setting. METHODS: One hundred and four children referred for evaluation of possible CD were prospectively recruited. Following informed consent, blood was drawn for serological testing and HLA analysis at upper gastrointestinal endoscopy. Histological findings according to Marsh criteria were correlated with blood results and the accuracy of the guideline analyzed.The study also examined the role of deamidated gliadin peptide (DGP) in the diagnosis of CD. RESULTS: For symptomatic patients with consistent HLA subtypes, strongly positive serology (as described in the ESPGHAN guidelines) accurately predicted biopsy-proven CD in >95% of cases. DGP was positive in fewer patients than anti-TG2 or EMA. Incorporation of DGP as a second confirmatory serological test in place of EMA was associated with maintained predictive value of guideline, but fewer patients fulfilling criteria for biopsy-free diagnosis. CONCLUSIONS: The ESPGHAN guideline performs well in our population. Adoption of the guideline would reduce the number of patients requiring endoscopy without compromise in diagnostic accuracy. The involvement of pediatric gastroenterological expertise, however, remains key to diagnosis of CD.

Health Risks and Adverse Reactions to Functional Foods.

Functional foods have become increasingly popular with consumers anxious to mitigate the effects of an unhealthy lifestyle or aging. In spite of attractive health claims, these products do not have legal or regulatory status in most countries and are regulated through their health claims. Regulation of functional foods by health claims does not address health risks and adverse effects of these products. In this essay regulatory aspects of functional foods are reviewed along with adverse effects published in the peer-reviewed literature. We detail why the lack of an internationally accepted definition of functional foods places consumers at risk of adverse outcomes. Our review will assist regulatory agencies, manufacturers and consumer groups to assess the benefits and reduce the risks associated with these products.

Profound Reversible Hypogammaglobulinemia Caused by Celiac Disease in the Absence of Protein Losing Enteropathy.

When patients with hypogammaglobulinemia are encountered, a vigorous search should be undertaken for secondary treatable causes. Here we describe the first case of a patient with severe asymptomatic hypogammaglobulinemia where the underlying cause was undiagnosed celiac disease. A strict gluten free diet resulted in resolution of her mild long-standing abdominal symptoms and correction of her hypogammaglobulinemia. There was corresponding improvement in her duodenal histology and normalisation of her celiac serology. Protein losing enteropathy was unlikely to have been the mechanism of her profound hypogammaglobulinemia, as her albumin was within the normal range and she had a normal fecal alpha 1 antitrypsin level. Application of the Ameratunga et al. (2013) diagnostic criteria was helpful in confirming this patient did not have Common Variable Immunodeficiency Disorder (CVID). Celiac disease must now be considered in the differential diagnosis of severe hypogammaglobulinemia. There should be a low threshold for undertaking celiac serology in patients with hypogammaglobulinemia, even if they have minimal symptoms attributable to gut disease.

Identification of germinal centres in the lymph node of a patient with hyperimmunoglobulin M syndrome associated with congenital rubella.

BACKGROUND: The hyper immunoglobulin M syndrome (HIM) associated with congenital rubella infection (rHIM) is an extremely rare disorder, where patients have elevated serum IgM in association with reduced IgG and IgA. We have previously shown that in contrast to X-linked HIM (XHIM), a patient with well-characterised rHIM is able to express functional CD40 ligand, undergo immunoglobulin isotype switching and to generate memory B cells. Here we describe the ultrastructural features of an excised lymph node from this patient. METHODS: An inguinal lymph node was surgically removed and examined histologically as well as by immunohistochemistry. It was then stained with multiple fluorescent dyes to visualize the cellular interactions within the node. Flow cytometry was undertaken on a cellular suspension from the node. FINDINGS: Our patient has normal lymph node architecture by light microscopy. Immunohistochemistry studies showed the presence of scattered germinal centres. Polychromatic immunofluorescence staining showed disruption of the architecture with mostly abnormal germinal centres. A small number of relatively intact germinal centres were identified. Both IgM and IgG bearing cells were identified in germinal centres. INTERPRETATION: In contrast to XHIM where germinal centres are absent, the presence of small numbers of relatively normal germinal centres explain our previous identification of isotype switched memory B cells in rHIM.

Detection of interferon alpha and beta receptor subunit 1 (IFNAR1) loss-of-function Glu386∗ variant by tri-allelic genotyping.

Mutations of the human interferon alpha and beta receptor subunit 1 (IFNAR1) gene are associated with severe viral infections. Individuals homozygous for the Glu386∗ variant have impaired type I interferon signalling and can suffer severe illness when exposed to certain viruses and live attenuated virus vaccines. Glu386∗ heterozygotes are clinically unaffected, but can pass the variant allele to their descendants. We aimed to develop an assay that can identify IFNAR1 Glu386∗ homozygotes and heterozygotes to support urgent clinical diagnosis, and that can use dried blood spots (DBS) sent at ambient temperature to overcome geographical logistical challenges in the South Pacific region. The tri-allelic genotyping assay interrogates a single nucleotide polymorphism (rs201609461) located in IFNAR1. The reference allele G encodes for wild-type IFNAR1. Minor alleles A (c.1156G>A) and T (c.1156G>T) encode for Glu386Lys and a truncated IFNAR1 protein (p.Glu386∗), respectively. Synthetic oligonucleotides were mixed in equal molar ratio to create six different genotypes which were randomly assigned to 960 genotyping reactions by R software. Three different fluorescence probes were designed to discriminate the three alleles (G, T and A) within a pair of flanking primers in a single genotyping reaction. The assay discriminated all three alleles using DBS from Guthrie cards randomly spiked with synthetic oligonucleotides. We correctly identified all the different genotypes in 960 reactions in these blinded experiments. These findings validate the genotyping assay for rapidly identifying the IFNAR1 Glu386∗ variant from DBS.

SARS-CoV-2 evolution has increased resistance to monoclonal antibodies and first-generation COVID-19 vaccines: Is there a future therapeutic role for soluble ACE2 receptors for COVID-19?

COVID-19 has caused calamitous health, economic and societal consequences. Although several COVID-19 vaccines have received full authorization for use, global deployment has faced political, financial and logistical challenges. The efficacy of first-generation COVID-19 vaccines is waning and breakthrough infections are allowing ongoing transmission and evolution of SARS-CoV-2. Furthermore, COVID-19 vaccine efficacy relies on a functional immune system. Despite receiving three primary doses and three or more heterologous boosters, some immunocompromised patients may not be adequately protected by COVID-19 vaccines and remain vulnerable to severe disease. The evolution of new SARS-CoV-2 variants has also resulted in the rapid obsolescence of monoclonal antibodies. Convalescent plasma from COVID-19 survivors has produced inconsistent results. New drugs such as Paxlovid (nirmatrelvir/ritonavir) are beyond the reach of low- and middle-income countries. With widespread use of Paxlovid, it is likely nirmatrelvir-resistant clades of SARS-CoV-2 will emerge in the future. There is thus an urgent need for new effective anti-SARS-CoV-2 treatments. The in vitro efficacy of soluble ACE2 against multiple SARS-CoV-2 variants including omicron (B.1.1.529), was recently described using a competitive ELISA assay as a surrogate marker for virus neutralization. This indicates soluble wild-type ACE2 receptors are likely to be resistant to viral evolution. Nasal and inhaled treatment with soluble ACE2 receptors has abrogated severe disease in animal models of COVID-19. There is an urgent need for clinical trials of this new class of antiviral therapeutics, which could complement vaccines and Paxlovid.

Phenotypic spectrum in a family with a novel RAC2 p.I21S dominant-activating mutation.

Objectives: Dominant-activating (DA) lesions in RAC2 have been reported in 18 individuals to date. Some have required haematopoietic stem cell transplantation (HSCT) for their (severe) combined immunodeficiency syndrome phenotype. We aimed to investigate clinical and cellular features of a kindred harbouring a novel variant in RAC2 p.Ile21Ser (I21S) to better understand DA lesions' phenotypic spectrum. Methods: Clinical and immunological information was collated for seven living individuals from the same kindred with RAC2 p.I21S. We evaluated neutrophil morphology, RAC2 protein expression and superoxide production using freshly isolated neutrophils stimulated with phorbol-12-myristate-13-acetate (PMA) and N-formyl-MetLeuPhe (fMLP). Results: Patient 1 (P1, aged 11, male) has a history of bacterial suppurative otitis media, viral and bacterial cutaneous infections. P1's siblings (P2, P3), mother (P4), maternal aunt (P5) and uncle (P6) have similar infection histories. P1's maternal cousin (P7) presented with Burkitt's lymphoma at age 9. All affected individuals are alive and none has required HSCT to date. They have chronic lymphopenia affecting the CD4+T and B-cell compartments. P1-3 have isolated reduction in IgM levels whereas the adults universally have normal immunoglobulins. Specific antibody responses are preserved. Affected individuals have neutrophil vacuolation, and their neutrophils have enhanced superoxide production compared to healthy controls. Conclusion: RAC2 p.I21S is an activating variant causing notable morphological and functional abnormalities similar to other reported DA mutations. This novel variant expands the broad clinical phenotypic spectrum of RAC2 DA lesions, emphasising the need to tailor clinical management according to patients' disease phenotype and severity.

The autoimmune rheumatological presentation of Common Variable Immunodeficiency Disorders with an overview of genetic testing.

Primary immunodeficiency Disorders (PIDS) are rare, mostly monogenetic conditions which can present to a number of specialties. Although infections predominate in most PIDs, some individuals can manifest autoimmune or inflammatory sequelae as their initial clinical presentation. Identifying patients with PIDs can be challenging, as some can present later in life. This is often seen in patients with Common Variable Immunodeficiency Disorders (CVID), where symptoms can begin in the sixth or even seventh decades of life. Some patients with PIDs including CVID can initially present to rheumatologists with autoimmune musculoskeletal manifestations. It is imperative for these patients to be identified promptly as immunosuppression could lead to life-threatening opportunistic infections in these immunocompromised individuals. These risks could be mitigated by prior treatment with subcutaneous or intravenous (SCIG/IVIG) immunoglobulin replacement or prophylactic antibiotics. Importantly, many of these disorders have an underlying genetic defect. Individualized treatments may be available for the specific mutation, which may obviate or mitigate the need for hazardous broad-spectrum immunosuppression. Identification of the genetic defect has profound implications not only for the patient but also for affected family members, who may be at risk of symptomatic disease following an environmental trigger such as a viral infection. Finally, there may be clinical clues to the underlying PID, such as recurrent infections, the early presentation of severe or multiple autoimmune disorders, as well as a relevant family history. Early referral to a clinical immunologist will facilitate appropriate diagnostic evaluation and institution of treatment such as SCIG/IVIG immunoglobulin replacement. This review comprises three sections; an overview of PIDs, focusing on CVID, secondly genetic testing of PIDs and finally the clinical presentation of these disorders to rheumatologists.

Clinical variability of family members with the C104R mutation in transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI).

PURPOSE: Common Variable Immunodeficiency Disorder (CVID) is a complex disorder that predisposes patients to recurrent and severe infections. The C104R mutation in the transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) is the most frequent mutation identified in patients with CVID. We carried out a detailed immunological and molecular study in a family with a C104R mutation. METHODS: We have undertaken segregation analysis of a kindred with C104R mutations of the TACI gene. Detailed immunological and molecular investigations were carried out for this kindred and the clinical phenotype was compared to the genotype. RESULTS: Segregation analysis of our kindred showed that inheriting single or double copy of the C104R mutation does not consign an individual to CVID. All heterozygotes in the family were phenotypically different, ranging from asymptomatic to ill-health. A family member with a wild type TACI variant had CVID-related phenotype including IgA deficiency and type 1 diabetes. Interestingly, a family member with the homozygous C104R/C104R variant did not meet the criteria for CVID because he had excellent, albeit unsustained, vaccine responses to T cell dependent and T cell independent vaccine antigens despite profound hypogammaglobulinemia. CONCLUSION: The C104R mutation does not correlate with the clinical phenotypes in this family.

Diagnostic utility of modified gliadin peptide antibody assays in New Zealand children.

OBJECTIVE: The aim of the present study was to evaluate a panel of different antibody assays, including second-generation antigliadin kits, in a local paediatric population thought to be at risk for coeliac disease (CD). METHODS: Seventy-nine children, who tested positive for immunoglobulin A (IgA) antibodies to tissue transglutaminase (TG), underwent duodenal biopsy. At endoscopy, serum was collected from all of the patients, and 9 different coeliac antibody assays were performed, both as isolated assays and in combination. These included immunoglobulin A (IgA) anti-tissue transglutaminase (TGA), and IgA plus IgG anti-deamidated gliadin peptide (DGPAG). A diagnosis of CD was made if the biopsies showed Marsh grade 3 lesions. RESULTS: Twenty-four of 79 children had CD confirmed histologically. Only 39 of 79 were positive for Inova TGA, and 35 of 79 were positive for Inova DGPAG. Twenty-four of 39 who were TGA positive and 24 of 35 who were DGPAG positive had confirmed CD on biopsy. There was good correlation between TGA and DGPAG-positive predictive values. None of the modified gliadin tests produced false-negative results, and neither did the TGA. CONCLUSIONS: The Inova DGPAG and TGA assays have similar use in predicting CD in a selected paediatric population; however, in children who are positive for TGA when screened for CD, more than half have negative TGA serology when repeat testing is done at the time of biopsy. Those with persistent TGA positivity have only a 61.5% probability of having histologic CD, compared with 68.6% of those children positive for DGPAG.

Samter's triad in childhood: a warning for those prescribing NSAIDs.

Aspirin-exacerbated respiratory disease (AERD) has been recognized in adults with chronic asthma. Samter's triad is a subset of AERD where adult patients develop nasal polyps, asthma, and sensitivity to aspirin. This condition is thought not to occur before the third decade of life. We report a 13-year-old boy with nasal polyps who suffered a life-threatening exacerbation of asthma during a graded aspirin challenge. Resuscitation required positive pressure ventilation and inotropic support. Our observations confirm that classical Samter's triad can occur in children. We suggest that graded aspirin challenges in children are undertaken in a facility with equipment and staff trained for resuscitation. Consideration should be given to this rare complication when prescribing nonsteroidal anti-inflammatory drugs in the perioperative period. Suspicion of this condition merits referral to an immunologist for desensitization to aspirin.

Selective IgA Deficiency May Be an Underrecognized Risk Factor for Severe COVID-19.

SARS-CoV-2, the agent responsible for COVID-19, has wreaked havoc around the globe. Hundreds of millions of individuals have been infected and well over six million have died from COVID-19. Many COVID-19 survivors have ongoing physical and psychiatric morbidity, which will remain for the rest of their lives. Early in the pandemic, it became apparent that older individuals and those with comorbidities including obesity, diabetes mellitus, coronary artery disease, hypertension, and renal and pulmonary disease were at increased risk of adverse outcomes. It is also clear that some immunodeficient patients, such as those with innate or T cell-immune defects, are at greater risk from COVID-19. Selective IgA deficiency (sIgAD) is generally regarded as a mild disorder in which most patients are asymptomatic because of redundancy in protective immune mechanisms. Recent data indicate that patients with sIgAD may be at high risk of severe COVID-19. SARS-CoV-2 gains entry primarily through the upper respiratory tract mucosa, where IgA has a critical protective role. This may underlie the vulnerability of sIgAD patients to adverse outcomes from COVID-19. This perspective highlights the need for ongoing research into mucosal immunity to improve COVID-19 treatments for patients with sIgAD.