Immune tolerance breakdown in inborn errors of immunity: Paving the way to novel therapeutic approaches.

Up to 25% of the patients with inborn errors of immunity (IEI) also exhibit immunodysregulatory features. The association of immune dysregulation and immunodeficiency may be explained by different mechanisms. The understanding of mechanisms underlying immune dysregulation in IEI has paved the way for the development of targeted treatments. In this review article, we will summarize the mechanisms of immune tolerance breakdown and the targeted therapeutic approaches to immune dysregulation in IEI.

Inherited defects in the complement system.

The complement system plays an essential role in both innate and adaptive immune responses. Any dysregulation in this system can disturb normal host defense and alter inflammatory response leading to both infections and autoimmune diseases. The complement system can be activated through three different pathways. Inherited complement deficiencies have been described for all complement components and their regulators. Despite being rare diseases, complement deficiencies are often severe, with a frequent onset during childhood. We provide an overview of clinical disorders related to these disorders and describe current diagnostic strategies required for their comprehensive characterization and management.

Primary atopic disorders and chronic skin disease.

Primary atopic disorders (PADs) are monogenic diseases characterized by allergy or atopy-related symptoms as fundamental features. In patients with PADs, primary immune deficiency and immune dysregulation symptoms are usually coexist. Chronic skin disease, manifesting with erythroderma, severe atopic dermatitis or eczema, and urticaria, is one of the main features observed in PADs, such as hyper-IgE syndromes, Omenn syndrome, Wiskott-Aldrich syndrome, IPEX-linked syndrome, skin barrier disorders, as well as some autoinflammatory diseases. The recognition of PADs in the context of an allergic phenotype is crucial to ensure prompt diagnosis and appropriate treatment. This article provides an overview of the main PADs with skin involvement.

Activated phosphoinositide 3-dinase delta syndrome (APDS): An update.

Activated phosphoinositide 3-kinase delta syndrome (APDS) is a recently described form of inborn error of immunity (IEI) caused by heterozygous mutations in PIK3CD or PIK3R1 genes, respectively, encoding leukocyte-restricted catalytic p110δ subunit and the ubiquitously expressed regulatory p85 α subunit of the phosphoinositide 3-kinase δ (PI3Kδ). The first described patients with respiratory infections, hypogammaglobulinemia with normal to elevated IgM serum levels, lymphopenia, and lymphoproliferation. Since the original description, it is becoming evident that the onset of disease may be somewhat variable over time, both in terms of age at presentation and in terms of clinical and immunological complications. In many cases, patients are referred to various specialists such as hematologists, rheumatologists, gastroenterologists, and others, before an immunological evaluation is performed, leading to delay in diagnosis, which negatively affects their prognosis. The significant heterogeneity in the clinical and immunological features affecting APDS patients requires awareness among clinicians since good results with p110δ inhibitors have been reported, certainly ameliorating these patients' quality of life and prognosis.

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.

Chronic cough in childhood: A systematic review for practical guidance by the Italian Society of Pediatric Allergy and Immunology.

The current systematic review presented and discussed the most recent studies on pediatric chronic cough. In addition, the Italian Society of Pediatric Allergy and Immunology elaborated a comprehensive algorithm to guide the primary care approach to a pediatric patient with chronic cough.Several algorithms on chronic cough management have been adopted and validated in clinical practice; however, unlike the latter, we developed an algorithm focused on pediatric age, from birth until adulthood. Based on our findings, children and adolescents with chronic cough without cough pointers can be safely managed, initially using the watchful waiting approach and, successively, starting empirical treatment based on cough characteristics. Unlike other algorithms that suggest laboratory and instrumental investigations as a first step, this review highlighted the importance of a "wait and see" approach, consisting of parental reassurance and close clinical observation, also due to inter-professional collaboration and communication between general practitioners and specialists that guarantee better patient management, appropriate prescription behavior, and improved patient outcome. Moreover, the neonatal screening program provided by the Italian National Health System, which intercepts several diseases precociously, allowing to treat them in a very early stage, helps and supports a "wait and see" approach.Conversely, in the presence of cough pointers or persistence of cough, the patient should be tested and treated by the specialist. Further investigations and treatments will be based on cough etiology, aiming to intercept the underlying disease, prevent potentially irreversible tissue damage, and improve the general health of patients affected by chronic cough, as well as the quality of life of patients and their family.

Acute cough in children and adolescents: A systematic review and a practical algorithm by the Italian Society of Pediatric Allergy and Immunology.

The current systematic review presented and discussed the most recent studies on acute cough in pediatric age. After that, the Italian Society of Pediatric Allergy and Immunology elaborated a comprehensive algorithm to guide the primary care approach to pediatric patients, such as infants, children, and adolescents, with acute cough. An acute cough is usually consequent to upper respiratory tract infections and is self-resolving within a few weeks. However, an acute cough may be bothersome, and therefore remedies are requested, mainly by the parents. An acute cough may significantly affect the quality of life of patients and their family.Several algorithms for the management of acute cough have been adopted and validated in clinical practice; however, unlike the latter, we developed an algorithm focused on pediatric age, and, also, in accordance to the Italian National Health System, which regularly follows the child from birth to all lifelong. Based on our findings, infants from 6 months, children, and adolescents with acute cough without cough pointers can be safely managed using well-known medications, preferably non-sedative agents, such as levodropropizine and/or natural compounds, including honey, glycerol, and herb-derived components.

Characteristics and risk factors for SARS-CoV-2 in children tested in the early phase of the pandemic: a cross-sectional study, Italy, 23 February to 24 May 2020.

BackgroundVery few studies describe factors associated with COVID-19 diagnosis in children.AimWe here describe characteristics and risk factors for COVID-19 diagnosis in children tested in 20 paediatric centres across Italy.MethodsWe included cases aged 0-18 years tested between 23 February and 24 May 2020. Our primary analysis focused on children tested because of symptoms/signs suggestive of COVID-19.ResultsAmong 2,494 children tested, 2,148 (86.1%) had symptoms suggestive of COVID-19. Clinical presentation of confirmed COVID-19 cases included besides fever (82.4%) and respiratory signs or symptoms (60.4%) also gastrointestinal (18.2%), neurological (18.9%), cutaneous (3.8%) and other unspecific influenza-like presentations (17.8%). In multivariate analysis, factors significantly associated with SARS-CoV-2 positivity were: exposure history (adjusted odds ratio (AOR): 39.83; 95% confidence interval (CI): 17.52-90.55; p < 0.0001), cardiac disease (AOR: 3.10; 95% CI: 1.19-5.02; p < 0.0001), fever (AOR: 3.05%; 95% CI: 1.67-5.58; p = 0.0003) and anosmia/ageusia (AOR: 4.08; 95% CI: 1.69-9.84; p = 0.002). Among 190 (7.6%) children positive for SARS-CoV-2, only four (2.1%) required respiratory support and two (1.1%) were admitted to intensive care; all recovered.ConclusionRecommendations for SARS-CoV-2 testing in children should consider the evidence of broader clinical features. Exposure history, fever and anosmia/ageusia are strong risk factors in children for positive SARS-CoV-2 testing, while other symptoms did not help discriminate positive from negative individuals. This study confirms that COVID-19 was a mild disease in the general paediatric population in Italy. Further studies are needed to understand risk, clinical spectrum and outcomes of COVID-19 in children with pre-existing conditions.

Long-term follow-up of 168 patients with X-linked agammaglobulinemia reveals increased morbidity and mortality.

BACKGROUND: X-linked agammaglobulinemia (XLA) is the prototype of primary humoral immunodeficiencies. Long-term follow-up studies regarding disease-related complications and outcome are scarce. OBJECTIVE: Our aim was to describe the natural history of XLA. METHODS: A nationwide multicenter study based on the Italian Primary Immunodeficiency Network registry was established in 2000 in Italy. Affected patients were enrolled by documenting centers, and the patients' laboratory, clinical, and imaging data were recorded on an annual base. RESULTS: Data on the patients (N = 168) were derived from a cumulative follow-up of 1370 patient-years, with a mean follow-up of 8.35 years per patient. The mean age at diagnosis decreased after establishment of the Italian Primary Immunodeficiency Network registry (84 months before vs 23 months after). Respiratory, skin, and gastrointestinal manifestations were the most frequent clinical symptoms at diagnosis and during long-term follow-up. Regular immunoglobulin replacement treatment reduced the incidence of invasive infections. Affected patients developed chronic lung disease over time (47% after 40 years of follow-up) in the presence of chronic sinusitis (84%). Malignancies were documented in a minority of cases (3.7%). Overall survival for affected patients was significantly reduced when compared with that for the healthy male Italian population, and it further deteriorated in the presence of chronic lung disease. CONCLUSIONS: This is the first detailed long-term follow-up study for patients with XLA, revealing that although immunoglobulin replacement treatment reduces the incidence of invasive infections, it does not appear to influence the development of chronic lung disease. The overall survival of affected patients is reduced. Further studies are warranted to improve patients' clinical management and increase awareness among physicians.

Precisely Engineered Supported Gold Clusters as a Stable Catalyst for Propylene Epoxidation.

Designing a stable and selective catalyst with high H2 utilisation is of pivotal importance for the direct gas-phase epoxidation of propylene. This work describes a facile one-pot methodology to synthesise ligand-stabilised sub-nanometre gold clusters immobilised onto a zeolitic support (TS-1) to engineer a stable Au/TS-1 catalyst. A non-thermal O2 plasma technique is used for the quick removal of ligands with limited increase in particle size. Compared to untreated Au/TS-1 catalysts prepared using the deposition precipitation method, the synthesised catalyst exhibits improved catalytic performance, including 10 times longer lifetime (>20 days), increased PO selectivity and hydrogen efficiency in direct gas phase epoxidation. The structure-stability relationship of the catalyst is illustrated using multiple characterisation techniques, such as XPS, 31 P MAS NMR, DR-UV/VIS, HRTEM and TGA. It is hypothesised that the ligands play a guardian role in stabilising the Au particle size, which is vital in this reaction. This strategy is a promising approach towards designing a more stable heterogeneous catalyst.

Prevalence of Immunological Defects in a Cohort of 97 Rubinstein-Taybi Syndrome Patients.

Although recurrent infections in Rubinstein-Taybi syndrome (RSTS) are common, and probably multifactorial, immunological abnormalities have not been extensively described with only isolated cases or small case series of immune deficiency and dysregulation having been reported. The objective of this study was to investigate primary immunodeficiency (PID) and immune dysregulation in an international cohort of patients with RSTS. All published cases of RSTS were identified. The corresponding authors and researchers involved in the diagnosis of inborn errors of immunity or genetic syndromes were contacted to obtain up-to-date clinical and immunological information. Ninety-seven RSTS patients were identified. For 45 patients, we retrieved data from the published reports while for 52 patients, a clinical update was provided. Recurrent or severe infections, autoimmune/autoinflammatory complications, and lymphoproliferation were observed in 72.1%, 12.3%, and 8.2% of patients. Syndromic immunodeficiency was diagnosed in 46.4% of individuals. Despite the broad heterogeneity of immunodeficiency disorders, antibody defects were observed in 11.3% of subjects. In particular, these patients presented hypogammaglobulinemia associated with low B cell counts and reduction of switched memory B cell numbers. Immunoglobulin replacement therapy, antibiotic prophylaxis, and immunosuppressive treatment were employed in 16.4%, 8.2%, and 9.8% of patients, respectively. Manifestations of immune dysfunctions, affecting mostly B cells, are more common than previously recognized in patients with RSTS. Full immunological assessment is warranted in these patients, who may require detailed investigation and specific supportive treatment. Graphical Abstract.

The Italian Registry for Primary Immunodeficiencies (Italian Primary Immunodeficiency Network; IPINet): Twenty Years of Experience (1999-2019).

Primary immunodeficiencies (PIDs) are heterogeneous disorders, characterized by variable clinical and immunological features. National PID registries offer useful insights on the epidemiology, diagnosis, and natural history of these disorders. In 1999, the Italian network for primary immunodeficiencies (IPINet) was established. We report on data collected from the IPINet registry after 20 years of activity. A total of 3352 pediatric and adult patients affected with PIDs are registered in the database. In Italy, a regional distribution trend of PID diagnosis was observed. Based on the updated IUIS classification of 2019, PID distribution in Italy showed that predominantly antibody deficiencies account for the majority of cases (63%), followed by combined immunodeficiencies with associated or syndromic features (22.5%). The overall age at diagnosis was younger for male patients. The minimal prevalence of PIDs in Italy resulted in 5.1 per 100.000 habitants. Mortality was similar to other European registries (4.2%). Immunoglobulin replacement treatment was prescribed to less than one third of the patient cohort. Collectively, this is the first comprehensive description of the PID epidemiology in Italy.

Immunological basis of virus-host interaction in COVID-19.

COVID-19 is a complex new viral disease, in which a strict balance between anti-viral immune response and the ensuing organ inflammation has a critical role in determining the clinical course. In adults, compelling evidence exists indicating that an uncontrolled inflammatory response ("cytokine storm") is pivotal in determining disease progression and mortality. Children may rarely present with severe disease. Modulating factors related to the host's genetic factors, age-related susceptibility, and the capability to mount appropriate immune responses might play a role in control virus load at an early stage and regulating the inflammatory reaction. Elucidating these mechanisms seems crucial in developing target therapies according to patient's age, immunologic status, and disease evolution in COVID-19.

Endoscopic removal of tracheobronchial foreign bodies: results on a series of 51 pediatric patients.

PURPOSE: Rigid bronchoscopy (RB) is still considered the gold standard approach for the removal of airway foreign bodies (FBs) in children; however, flexible bronchoscopy (FOB) has recently been proposed both as diagnostic and therapeutic means. Our purpose was to evaluate the outcomes of FOB, associated with the Dormia basket, for the removal of FBs. METHODS: Retrospective data about 124 children who underwent bronchoscopy for the suspicion of a FB aspiration between January 2008 and January 2019 in our department were collected. RESULTS: In a total of 51 cases, FBs were removed through FOB or RB associated with forceps or Dormia basket. Male to female ratio was 1.8:1, mean age 30 ± 26.1 months. Thirty-four (67%) FBs were directly removed through FOB, in most of the cases using Dormia basket and twelve (23%) patients underwent RB. The overall left-versus-right distribution was 57% vs. 43%. The mean retrieval procedural time was 36.29 ± 24.99 min for FOB and 52.5 ± 29.74 min for RB; the success rate of the procedures was 97% vs. 67%. CONCLUSION: FOB can be used not only as a diagnostic procedure, but also as the first method for the removal of airway FBs. The Dormia basket is a useful tool, especially to remove peripherally located FBs.

A novel monoallelic gain of function mutation in p110δ causing atypical activated phosphoinositide 3-kinase δ syndrome (APDS-1).

This study reports on a novel activating p110δ mutation causing adult-onset hypogammaglobulinemia with lymphopenia without the classical presentation of atypical Activated phosphoinositide 3-kinase δ syndrome (ADPS-1), underlining thus the heterogeneous clinical and immunological presentation of p110δ mutated individuals and offers additional data on the role of p110δ in early and late B cell development in humans.

Efficacy and Adverse Events During Janus Kinase Inhibitor Treatment of SAVI Syndrome.

OBJECTIVES: Mutations affecting the TMEM173 gene cause STING-associated vasculopathy with onset in infancy (SAVI). No standard immunosuppressive treatment approach is able to control disease progression in patients with SAVI. We studied the efficacy and safety of targeting type I IFN signaling with the Janus kinase inhibitor, ruxolitinib. METHODS: We used DNA sequencing to identify mutations in TMEM173 in patients with peripheral blood type I IFN signature. The JAK1/2 inhibitor ruxolitinib was administered on an off-label basis. RESULTS: We identified three patients with SAVI presenting with skin involvement and progressive severe interstitial lung disease. Indirect echocardiographic signs of pulmonary hypertension were present in one case. Following treatment with ruxolitinib, we observed improvements of respiratory function including increased forced vital capacity in two patients, with discontinuation of oxygen therapy and resolution of echocardiographic abnormalities in one case. Efficacy was persistent in one patient and only transitory in the other two patients. Clinical control of skin complications was obtained, and one patient discontinued steroid treatment. One patient, who presented with kidney involvement, showed resolution of hematuria. One patient experienced increased recurrence of severe viral respiratory infections. Monitoring of peripheral blood type I interferon signature during ruxolitinib treatment did not show a stable decrease. CONCLUSIONS: We conclude that targeting type I IFN receptor signaling may represent a promising therapeutic option for a subset of patients with SAVI syndrome and severe lung involvement. However, the occurrence of viral respiratory infection might represent an important cautionary note for the application of such form of treatment.

Pollen-Food Allergy Syndrome: A not so Rare Disease in Childhood.

Seasonal allergic rhinoconjunctivitis (SAR) affects millions of people worldwide, particularly in childhood and adolescence. Pollen food allergy syndrome (PFAS) is a common adverse reaction occurring few minutes after the consumption of vegetable foods in patients with pollen-induced SAR. PFAS has rarely been investigated in the pediatric population, as it has been mainly examined as an adult disease. Recent studies suggested that PFAS might be more frequent in childhood than previously recognized. The present review aims to give an overview of the epidemiology, pathophysiology, diagnosis, management and prognosis of PFAS in children with SAR-induced by pollens.

Evaluating children with suspected allergic reactions to vaccines for infectious diseases.

BACKGROUND: Vaccines often contain potentially allergenic material in addition to pathogen-specific immunogens that may induce allergic reactions. Parents and physicians often suspect that adverse reactions to vaccines are allergic in etiology. The concern that some of the substances contained in vaccines may trigger an anaphylactic reaction may lead to a low vaccination adherence with emergence of infectious disease epidemics. OBJECTIVE: To provide practical suggestions for managing children suspected to have an allergic reaction to a vaccine. METHODS: Information was obtained from a search of guidelines and relevant studies on allergic reactions to vaccines for infectious diseases. RESULTS: True allergic reactions elicited by a vaccine are rare. Skin testing to the vaccine and to its components may identify the triggering agent. Graded dosing desensitization is helpful in children sensitized to the offending vaccine. CONCLUSION: All children with a suspected allergic reaction to a vaccine should be carefully evaluated by routine allergy tests. When it is necessary, further immunization should be given under strict medical surveillance, which ensures that every child can safely complete the vaccination schedule.

B-cell hyperfunction in children with immune thrombocytopenic purpura persists after splenectomy.

BACKGROUND: Immune thrombocytopenic purpura (ITP) is characterized by reduced platelet count secondary to immune-mediated destruction, this results in an increased bleeding risk. Autoantibodies binding to platelets tag them for premature destruction in the spleen. For this reason, splenectomy is often performed as treatment of chronic forms of disease that are resistant to pharmacological therapy. METHODS: We studied 30 patients with ITP and compared them with age-matched controls. RESULTS: We show that B cells of patients with chronic ITP are intrinsically hyperreactive, producing more than normal IgG in vivo and plasma cells in vitro. In normal individuals after splenectomy, a significant depletion of memory B cells is observed, associated with loss of reactivity to CpG oligodeoxynucleotide and consequent inability to form antibody-producing cells. In Enzyme-Linked ImmunoSpot Methods, we compared three splenectomized ITP patients relapsing after surgery, 30 healthy controls, and 37 individuals splenectomized for trauma, spherocytosis, thalassemia, nonhematological tumor, and other diseases. CONCLUSIONS: We confirmed that B cells of ITP patients remain hyperreactive in vitro and form high numbers of antibody-producing cells after splenectomy. Thus, chronic ITP may be associated with intrinsic B-cell hyperfunction, leading to the production of antibodies with multiple specificities including that against platelets.