Immunodeficiency-Associated Lymphoid Hyperplasia As a Cause of Intussusception in a Case of Activated PI3K-δ Syndrome

Systematic review of mortality and survival rates for APDS

Activated phosphoinositide 3-kinase delta syndrome (APDS) is a rare genetic disorder that presents clinically as a primary immunodeficiency. Clinical presentation of APDS includes severe, recurrent infections, lymphoproliferation, lymphoma, and other cancers, autoimmunity and enteropathy. Autosomal dominant variants in two independent genes have been demonstrated to cause APDS. Pathogenic variants in PIK3CD and PIK3R1, both of which encode components of the PI3-kinase, have been identified in subjects with APDS. APDS1 is caused by gain of function variants in the PIK3CD gene, while loss of function variants in PIK3R1 have been reported to cause APDS2. We conducted a review of the medical literature and identified 256 individuals who had a molecular diagnosis for APDS as well as age at last report; 193 individuals with APDS1 and 63 with APDS2. Despite available treatments, survival for individuals with APDS appears to be shortened from the average lifespan. A Kaplan-Meier survival analysis for APDS showed the conditional survival rate at the age of 20 years was 87%, age of 30 years was 74%, and ages of 40 and 50 years were 68%. Review of causes of death showed that the most common cause of death was lymphoma, followed by complications from HSCT. The overall mortality rate for HSCT in APDS1 and APDS2 cases was 15.6%, while the mortality rate for lymphoma was 47.6%. This survival and mortality data illustrate that new treatments are needed to mitigate the risk of death from lymphoma and other cancers as well as infection. These analyses based on real-world evidence gathered from the medical literature comprise the largest study of survival and mortality for APDS to date.

Clinical, Immunological, and Genetic Features in Patients with Activated PI3Kδ Syndrome (APDS): a Systematic Review

Activated phosphoinositide 3-kinase delta syndrome (APDS) is a novel primary immunodeficiency (PID) caused by heterozygous gain of function mutations in PI3Kδ catalytic p110δ (PIK3CD) or regulatory p85α (PIK3R1) subunits leading to APDS1 and APDS2, respectively. Patients with APDS present a spectrum of clinical manifestations, particularly recurrent respiratory infections and lymphoproliferation. We searched PubMed, Web of Science, and Scopus databases for APDS patients and screened for eligibility criteria. A total of 243 APDS patients were identified from 55 articles. For all patients, demographic, clinical, immunologic, and molecular data were collected. Overall, 179 APDS1 and 64 APDS2 patients were identified. The most common clinical manifestations were respiratory tract infections (pneumonia (43.6%), otitis media (28.8%), and sinusitis (25.9%)), lymphoproliferation (70.4%), autoimmunity (28%), enteropathy (26.7%), failure to thrive (20.6%), and malignancy (12.8%). The predominant immunologic phenotype was hyper-IgM syndrome (48.1%). Immunologic profiling showed decreased B cells in 74.8% and CD4⁺ T cells in 64.8% of APDS patients. The c.3061 G>A (p. E1021K) mutation in APDS1 with 85% frequency and c.1425+1 G> (A, C, T) (p.434-475del) mutation in APDS2 with 79% frequency were hotspot mutations. The majority of APDS patients were placed on long-term immunoglobulin replacement therapy. Immunosuppressive agents such as rituximab, tacrolimus, rapamycin, and leniolisib were also administered for autoimmunity and inflammatory complications. In addition, hematopoietic stem cell transplantation (HSCT) was used in 12.8% of patients. APDS has heterogynous clinical manifestations. It should be suspected in patients with history of recurrent respiratory infections, lymphoproliferation, and raised IgM levels. Moreover, HSCT should be considered in patients with severe and complicated clinical manifestations with no or insufficient response to the conventional therapies.

Infections in activated PI3K delta syndrome (APDS)

Activated PI3K-delta Syndrome (APDS), also called PI3K-delta activating mutation causing senescent T cells, lymphadenopathy, and immunodeficiency (PASLI), is an autosomal dominant disorder caused by inherited or de novo gain-of-function mutations in one of two genes encoding subunits of the phosphoinositide-3-kinase delta (PI3Kδ) complex. This largely leukocyte-restricted protein complex regulates cell growth, activation, proliferation, and survival. Patients who harbor these mutations have early onset immunodeficiency with recurrent infections, lymphadenopathy, and autoimmunity. The most common infection susceptibilities are sinopulmonary (encapsulated bacteria) and herpesviruses. Multiple defects in both innate and adaptive immune function are responsible for this phenotype. Apart from anti-microbial prophylaxis and immunoglobulin replacement, patients are treated with a variety of immunomodulatory agents and some have needed hematopoietic stem cell transplants. Here, we highlight the spectrum of infections, immune defects, and therapy options in this inborn error of immunity.

The First Iranian Cohort of Pediatric Patients with Activated Phosphoinositide 3-Kinase-δ (PI3Kδ) Syndrome (APDS)

Background: Activated phosphoinositide 3-kinase δ syndrome (APDS) is a recently defined combined primary immunodeficiency disease (PID) characterized by recurrent respiratory tract infections, lymphoproliferation, autoimmunity and lymphoma. Gain-of-function mutations in PIK3CD and loss-of-function of PIK3R1 genes lead to APDS1 and APDS2, respectively.Methods: Demographic, clinical, immunological and genetic data were collected from medical records of 15 pediatric patients, who were genetically identified using the whole-exome sequencing method.Results: Fifteen patients (6 APDS1 and 9 APDS2) were enrolled in this study. Recurrent respiratory tract infections followed by lymphoproliferation and autoimmunity were the most common manifestations (86.7%, 53.3% and 26.7%, respectively). Five patients (33.3%) had a Hyper-IgM-syndrome-like immunoglobulin profile. In the APDS1 group, splice site and missense mutations were found in half of the patients and the C-lobe domain of PIK3CD was the most affected region (50%). In the APDS2 group, splice site mutation was the most frequent mutation (77.8%) and the inter-SH2 domain was the most affected region of PIK3R1 (66.7%). Mortality rate was significantly higher in APDS2 group (P = .02) mainly due to chronic lung infections.Conclusion: Respiratory tract infections and humoral immunodeficiency are commonly the most important complication in pediatric APDS patients, and they can be fatal by ultimately causing catastrophic damage to the structure of lungs. Hence, physicians should be aware of its significance and further work-up of patients with recurrent respiratory tract infections especially in patients with lymphoproliferation. Moreover, delineation of genotype-phenotype associations with disease severity could be helpful in the timely application of appropriate management and patients' survival.

Transcriptome changes of Takifugu obscurus liver after acute exposure to the oxygenated-PAH 9,10-phenanthrenequione

Contamination with polycyclic aromatic hydrocarbons (PAHs) causes noticeable ecological problems in aquatic ecosystems. 9,10-Phenanthrenequione (9,10-PQ) is an oxidized PAH and is highly toxic to aquatic animals. However, the effects of 9,10-PQ on the molecular metabolism of fish remain largely unknown. In this study, Takifugu obscurus juveniles were acutely exposed to 44.30 µg/L 9,10-PQ for 3 days. The transcriptome profile changes in their livers were compared between the 9,10-PQ treatment group and the control using T. rubripes as the reference genome. The results identified 22,414 genes in our transcriptome. Among them, 767 genes were differentially expressed after exposure to 9,10-PQ, which enriched 16 KEGG pathways. Among them, the glycolysis, phagosome, and FOXO signaling pathways were significantly activated in 9,10-PQ treatment compared with the control. These data indicate that 9,10-PQ increased the glycolysis capacity to produce more energy for resistance and harmed immune function. Moreover, several genes related to tumorigenesis were significantly upregulated in response to 9,10-PQ, displaying the carcinogenic toxicity of 9,10-PQ to T. obscurus. Genes in steroid biosynthesis pathways were downregulated in the 9,10-PQ treatment group, suggesting interference with the endocrine system. Overall, these findings provide information to help evaluate the environmental risks that oxygenated-PAHs present to T. obscurus.

T and B-cell signaling in activated PI3K delta syndrome: From immunodeficiency to autoimmunity

Phosphatidylinositol 3 kinases (PI3K) are a family of lipid kinases that are activated by a variety of cell-surface receptors, and regulate a wide range of downstream readouts affecting cellular metabolism, growth, survival, differentiation, adhesion, and migration. The importance of these lipid kinases in lymphocyte signaling has recently been highlighted by genetic analyses, including the recognition that both activating and inactivating mutations of the catalytic subunit of PI3Kδ, p110δ, lead to human primary immunodeficiencies. In this article, we discuss how studies on the human genetic disorder "Activated PI3K-delta syndrome" and mouse models of this disease (Pik3cd^E1020K/+ mice) have provided fundamental insight into pathways regulated by PI3Kδ in T and B cells and their contribution to lymphocyte function and disease, including responses to commensal bacteria and the development of autoimmunity and tumors. We highlight critical roles of PI3Kδ in T follicular helper cells and the orchestration of the germinal center reaction, as well as in CD8⁺ T-cell function. We further  present data demonstrating the ability of the AKT-resistant FOXO1^AAA mutant to rescue IgG1 class switching defects in Pik3cd^E1020K/+ B cells, as well as data supporting a role for PI3Kδ in promoting multiple T-helper effector cell lineages.

An updated review on activated PI3 kinase delta syndrome (APDS)

Activated Phosphoinositide 3-kinase δ syndrome (APDS) is a newly recognised primary immunodeficiency disease. It has currently been a hot topic of clinical research and new data are emerging regarding its pathogenesis, clinical manifestations and treatment. Patients with APDS syndrome have significant autoimmune manifestations and lymphoproliferation. It is important to differentiate APDS from the usual polygenic CVID in view of the availability of targeted therapy like mTOR inhibitors such as Rapamycin and selective PI3Kδ inhibitors. We provide a comprehensive review on this interesting disorder focusing light on its etiology, genetic research and emerging therapy.

Diagnosis and management of chronic and refractory immune cytopenias in children, adolescents, and young adults

Children, adolescents, and young adults with chronic refractory autoimmune cytopenias represent a rare but challenging group of patients, who are managed frequently by pediatric hematologists. Novel diagnostic tests and genomic discoveries are refining historical diagnoses of Evans syndrome and common variable immunodeficiency, while also elucidating the cellular and molecular basis for these disorders. Genetic characterization of chronic and refractory autoimmune cytopenias has led to targeted therapies with improved clinical outcomes and fewer off-target toxicities. In this review, we focus on the appropriate diagnostic workup, expanded genetic testing, and novel treatment opportunities that are available for these challenging patients.

Bacille Calmette-Guerin Complications in Newly Described Primary Immunodeficiency Diseases: 2010-2017

Bacille Calmette–Guerin (BCG) vaccine is widely used as a prevention strategy against tuberculosis. BCG is a live vaccine, usually given early in life in most countries. While safe to most recipients, it poses a risk to immunocompromised patients. Several primary immunodeficiency diseases (PIDD) have been classically associated with complications related to BCG vaccine. However, a number of new inborn errors of immunity have been described lately in which little is known about adverse reactions following BCG vaccination. The aim of this review is to summarize the existing data on BCG-related complications in patients diagnosed with PIDD described since 2010. When BCG vaccination status or complications were not specifically addressed in those manuscripts, we directly contacted the corresponding authors for further clarification. We also analyzed data on other mycobacterial infections in these patients. Based on our analysis, around 8% of patients with gain-of-function mutations in STAT1 had mycobacterial infections, including localized complications in 3 and disseminated disease in 4 out of 19 BCG-vaccinated patients. Localized BCG reactions were also frequent in activated PI3Kδ syndrome type 1 (3/10) and type 2 (2/18) vaccinated children. Also, of note, no BCG-related complications have been described in either CTLA4 or LRBA protein-deficient patients; and not enough information on BCG-vaccinated NFKB1 or NFKB2-deficient patients was available to drive any conclusions about these diseases. Despite the high prevalence of environmental mycobacterial infections in GATA2-deficient patients, only one case of BCG reaction has been reported in a patient who developed disseminated disease. In conclusion, BCG complications could be expected in some particular, recently described PIDD and it remains a preventable risk factor for pediatric PIDD patients.

Respiratory Manifestations of the Activated Phosphoinositide 3-Kinase Delta Syndrome

The activated phosphoinositide 3-kinase δ syndrome (APDS), also known as p110δ-activating mutation causing senescent T cells, lymphadenopathy, and immunodeficiency (PASLI), is a combined immunodeficiency syndrome caused by gain-of-function mutations in the phosphoinositide 3-kinase (PI3K) genes PIK3CD (encoding p110δ: APDS1 or PASLI-CD) and PIK3R1 (encoding p85α: APDS2 or PASLI-R1). While the disease is clinically heterogeneous, respiratory symptoms and complications are near universal and often severe. Infections of the ears, sinuses, and upper and lower respiratory tracts are the earliest and most frequent manifestation of APDS, secondary to both respiratory viruses and to bacterial pathogens typical of defective B cell function. End organ damage in the form of small airways disease and bronchiectasis frequently complicates APDS, but despite documented T cell defects, opportunistic infections have rarely been observed. Antimicrobial (principally antibiotic) prophylaxis and/or immunoglobulin replacement have been widely used to reduce the frequency and severity of respiratory infection in APDS, but outcome data to confirm the efficacy of these interventions are limited. Despite these measures, APDS patients are often afflicted by benign lymphoproliferative disease, which may present in the respiratory system as tonsillar/adenoidal enlargement, mediastinal lymphadenopathy, or mucosal nodular lymphoid hyperplasia, potentially causing airways obstruction and compounding the infection phenotype. Treatment with rapamycin and PI3Kδ inhibitors has been reported to be of benefit in benign lymphoproliferation, but hematopoietic stem cell transplantation (ideally undertaken before permanent airway damage is established) remains the only curative treatment for APDS.

Epstein-Barr Virus Susceptibility in Activated PI3Kδ Syndrome (APDS) Immunodeficiency

Activated PI3Kδ Syndrome (APDS) is an inherited immune disorder caused by heterozygous, gain-of-function mutations in the genes encoding the phosphoinositide 3-kinase delta (PI3Kδ) subunits p110δ or p85δ. This recently described primary immunodeficiency disease (PID) is characterized by recurrent sinopulmonary infections, lymphoproliferation, and susceptibility to herpesviruses, with Epstein–Barr virus (EBV) infection being most notable. A broad range of PIDs having disparate, molecularly defined genetic etiology can cause susceptibility to EBV, lymphoproliferative disease, and lymphoma. Historically, PID patients with loss-of-function mutations causing defective cell-mediated cytotoxicity or antigen receptor signaling were found to be highly susceptible to pathological EBV infection. By contrast, the gain of function in PI3K signaling observed in APDS patients paradoxically renders these patients susceptible to EBV, though the underlying mechanisms are incompletely understood. At a cellular level, APDS patients exhibit deranged B lymphocyte development and defects in class switch recombination, which generally lead to defective immunoglobulin production. Moreover, APDS patients also demonstrate an abnormal skewing of T cells toward terminal effectors with short telomeres and senescence markers. Here, we review APDS with a particular focus on how the altered lymphocyte biology in these patients may confer EBV susceptibility.