SARS-CoV-2-specific mucosal immune response in vaccinated versus infected children.

The anti-COVID-19 intramuscular vaccination induces a strong systemic but a weak mucosal immune response in adults. Little is known about the mucosal immune response in children infected or vaccinated against SARS-CoV-2. We found that 28% of children had detectable salivary IgA against SARS-CoV-2 even before vaccination, suggesting that, in children, SARS-CoV-2 infection may be undiagnosed. After vaccination, only receptor-binding domain (RBD)-specific IgA1 significantly increased in the saliva. Conversely, infected children had significantly higher salivary RBD-IgA2 compared to IgA1, indicating that infection more than vaccination induces a specific mucosal immune response in children. Future efforts should focus on development of vaccine technologies that also activate mucosal immunity.

Respiratory Syncytial Virus Bronchiolitis Before and After COVID-19 Pandemic: Has the Immunity Debt Been Paid Off?

BACKGROUND: Our aim was to hypothesize that the COVID-19 pandemic influenced the characteristics of viral bronchiolitis by comparing the last 3 epidemics with 3 pre-COVID-19 epidemics in infants hospitalized with bronchiolitis. METHODS: We prospectively enrolled 637 consecutive infants (median age 3.0 ± 2.1 months, 58.5% males), hospitalized for bronchiolitis during 6 consecutive annual epidemic seasons from 2017 to 2023. All parents of the children were given a structured anamnestic questionnaire. A nasopharyngeal aspirate was tested for 15 respiratory viruses. As measures of severity, we evaluated the O2 supplementation and the admission at the pediatric intensive care unit. RESULTS: A total of 166 were hospitalized with bronchiolitis in 2017-2018, 97 in 2018-2019, 69 in 2019-2020, 0 in 2020-2021, 129 in 2021-2022 and 176 in 2022-2023. Taking together the 332 bronchiolitis cases hospitalized during the 3 prepandemic seasons, they peaked between December and January; after the flat curve in 2020-2021, the cases of bronchiolitis peaked in November 2021 and in December 2022. While the 2021-2022 season registered a less severe clinical presentation, O2 supplementation and pediatric intensive care unit admissions increased in 2022-2023 with respect to the prepandemic seasons (P < 0.001). CONCLUSIONS: This study represents an important scientific demonstration of the impact of primary prevention measures on the epidemiology of viral infections; their fluctuations were related to the intensity of restrictive measures and to the changing trend of respiratory viruses. It is essential to predict the real temporal trend of bronchiolitis in order not to leave high-risk children uncovered and to guide hospitals to maintain a high level of readiness.

Age-related transcript changes in type I interferon signaling in children and adolescents with long COVID.

SARS-CoV-2 typically causes mild symptoms in children, but evidence suggests that persistent immunopathological changes may lead to long COVID (LC). To explore the interplay between LC and innate immunity, we assessed the type I interferon (IFN-I) response in children and adolescents with LC symptoms (LC; n = 28). This was compared with age-matched SARS-CoV-2 recovered participants without LC symptoms (MC; n = 28) and healthy controls (HC; n = 18). We measured the mRNA expression of IFN-I (IFN-α/ß/ε/ω), IFN-I receptor (IFNAR1/2), and ISGs (ISG15, ISG56, MxA, IFI27, BST2, LY6E, OAS1, OAS2, OAS3, and MDA5) in PBMCs collected 3-6 months after COVID-19. LC adolescents (12-17 years) had higher transcript levels of IFN-ß, IFN-ε, and IFN-ω than HC, whereas LC children (6-11 years) had lower levels than HC. In adolescents, increased levels of IFN-α, IFN-ß, and IFN-ω mRNAs were found in the LC group compared with MC, while lower levels were observed in LC children than MC. Adolescents with neurological symptoms had higher IFN-α/ß mRNA levels than MC. LC and MC participants showed decreased expression of ISGs and IFNAR1, but increased expression of IFNAR2, than HC. Our results show age-related changes in the expression of transcripts involved in the IFN-I signaling pathway in children and adolescents with LC.

ERS International Congress 2023: highlights from the Paediatrics Assembly.

Respiratory health in children is essential for general wellbeing and healthy development in the short and long term. It is well known that many respiratory diseases in adulthood have their origins in early life, and therefore research on prevention of respiratory diseases and management of children with respiratory diseases will benefit patients during the full life course. Scientific and clinical advances in the field of respiratory health are moving at a fast pace. This article summarises some of the highlights in paediatric respiratory medicine presented at the hybrid European Respiratory Society (ERS) International Congress 2023 which took place in Milan (Italy). Selected sessions are summarised by Early Career Members of the Paediatrics Assembly (Assembly 7) under the supervision of senior ERS officers, and cover a wide range of research areas in children, including respiratory physiology and sleep, asthma and allergy, cystic fibrosis, respiratory infection and immunology, neonatology and intensive care, respiratory epidemiology and bronchology.

Acute Bronchiolitis: The Less, the Better?

BACKGROUND: Acute bronchiolitis is a viral infection of the lower respiratory tract affecting infants aged under 12 months, variably presenting with respiratory distress, diffuse crackles and inflammatory wheezing. The main causative agent is Respiratory Syncytial Virus (RSV). The diagnosis is clinical and treatment mainly supportive. Despite the availability of more than 30 international guidelines, consistent management recommendations are lacking and considerable variability in patients' care persists among different providers. OBJECTIVE: To review and describe current knowledge about epidemiology, physiopathology, clinic, diagnosis and management of acute bronchiolitis, with particular emphasis on updated evidence and future perspectives in terms of treatment and prevention. METHODS AND RESULTS: We searched Cochrane for systematic reviews and PubMed for scientific articles published in the last 10 years, using a combination of the following search terms: "bronchiolitis", "respiratory syncytial virus", "epidemiology", "risk factors", "severity", "diagnosis", "clinic", "diagnostic imaging", "management", "asthma", "wheezing", "bronchodilator", "steroids", "hypertonic saline", "oxygen", "blood gas analysis", "HHHFNC", "rehydration", "enteral feeding", "parenteral hydration", "prevention", "vaccine" and "COVID-19 or SARS-CoV2". We accordingly performed a deep and extensive selection of the most updated and considerable literature on the matter, summarizing the most significant evidence concerning all aspects of acute bronchiolitis (epidemiology, clinic, diagnosis, management and prevention). Furthermore, we examined references and available guidelines from UK, USA, Canada, Italy and Spain. Results are extensively discussed below. CONCLUSION: Although acute bronchiolitis has been a widely known disease for decades, its therapeutic approach remained unchanged and essentially limited to respiratory and metabolic support. Despite the abundance of studies, there is no significant evidence concerning therapeutic alternatives (e.g. steroids, inhaled hypertonic solution), which are therefore not recommended. According to most recent data, "acute bronchiolitis" definition encompasses a plethora of different clinical entities related to each subject's genetic and immune predisposition. Therefore, future research should focus on the precise characterization of such subcategories in order to individualize therapeutic management and ensure the most appropriate evidence-based care.

Investigating the Relationship Between COVID-19 and Celiac Disease. A Dual Research Approach.

Background: Most evidence on the coronavirus disease 2019 (COVID-19) pandemic, has been obtained from web- or telephone-based surveys. In particular, few laboratory data, often incomplete, have been reported on the frequency of COVID-19-related serology at celiac disease (CD) diagnosis or on the effects of COVID-19 on the development of CD-specific autoimmunity. Objectives: The objective of this retrospective cross-sectional case/control study was to: (1) evaluate the frequency of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in 78 children and adolescents at CD diagnosis (CD, 44 females, median age 7.4 years); (2) evaluate the frequency of IgA-anti-transglutaminase antibodies (IgA-tTGAbs) in 97 nonceliac patients (50 females, median age 9.0 years) who contracted SARS-CoV-2 infection during the pandemic (February-April 2021). As a control (CTRL) group, we analyzed 141 healthy subjects (79 females, median age 9.8 years) enrolled during the pandemic. Methods: SARS-CoV-2 IgM- and IgG-antibodies were detected by chemiluminescent microparticle immunoassays. IgA-tTGAbs were detected by a fluid-phase radioimmunoassay. Results: Six out of 78 (7.7%) CD patients tested positive for SARS-CoV-2Abs, with a frequency not significantly different from CTRL subjects (9.2%). None of the 97 nonceliac COVID-19 patients tested positive for IgA-tTG antibodies. Conclusion: These 2 distinct research approaches showed (1) similar frequencies of SARS-CoV-2 immunoreactivities in CD patients and CTRL subjects and, (2) no ability of SARS-CoV-2 to induce a CD-specific immune response, at least in the 3-4 months following SARS-CoV-2 infection.

A Single Center Observational Study on Clinical Manifestations and Associated Factors of Pediatric Long COVID.

Children with SARS-CoV-2 are mostly mild symptomatic, but they may develop conditions, such as persisting symptoms, that may put them at greater risk of complications. Our aim was to evaluate the frequency and the presence of risk factors for persisting COVID-19 symptoms in children. We carried out a prospective observational study of the clinical manifestation of Long COVID at the Department of Maternal Infantile Science of a tertiary University hospital in Rome. We included 697 children (0-18 years), with previous SARS-CoV-2 infection. Children and parents were asked questions regarding persistent symptoms of COVID-19. Children with symptoms 30 days after initial diagnosis were 185/697 (26.4%). Moreover, 81/697 (11.6%) patients presented symptoms 90 days after the diagnosis. Thirty-day-persisting symptoms were mostly present in children with anosmia, atopy, asthenia, and cough in the acute phase compared with the asymptomatic children 30 days after infection. After 90 days, symptoms described were mainly neurological (47/697 children, 6.7%), and headache (19/697; 2.7%) was the most frequent manifestation. In conclusion, a relatively large proportion of the patients reported persisting symptoms that seem to be related to the symptom burden and to the atopy. Ninety days after the infection, most of the children had recovered, showing that long-term effects are not frequent. Limitations of the study include the single-center design and the lack of a control group.

No effects of COVID-19 on the development of type 1 diabetes autoimmunity and no evidence of an increased frequency of SARS-CoV-2 antibodies in newly diagnosed type 1 diabetes patients relative to healthy subjects.

AIMS: To evaluate the relationship between SARS-CoV-2 infection and autoimmunity in type 1 diabetes (T1D) and SARS-CoV-2 antibodies frequency at diagnosis of T1D during pandemic. METHODS: The presence of T1D-specific autoimmunity was evaluated in a cohort of 99 children and adolescents without diabetes that contracted SARS-CoV-2 infection. Moreover, the frequency of IgM- and IgG-SARS-CoV-2 antibodies was evaluated in 41 newly diagnosed T1D patients not yet vaccinated against SARS-CoV-2 disease, collected during the pandemic, compared to healthy subjects (CTRL). RESULTS: None of the 99 patients that contracted SARS-CoV-2 infection during the pandemic period was found positive for T1D autoantibodies. The frequency of SARS-CoV-2 antibodies was not significantly different in patients newly diagnosed with T1D (12.2%), compared with CTRL (8.4%). Among SARS-CoV-2 antibody positive T1D patients, 80% were target of diabetes autoantibodies and 60% had another concomitant autoimmune disease. Among the CTRL subjects positive for SARS-CoV-2Abs (n = 10), none was found positive for T1D autoantibodies. CONCLUSIONS: The results of the present study do not confirm, at least in the short term, a role of COVID-19 as a potential trigger of T1D autoimmunity and do not provide evidence of an increased frequency of SARS-CoV-2 antibodies in newly diagnosed T1D patients in comparison with healthy population.

ERS International Congress 2022: highlights from the Paediatrics Assembly.

This review has been prepared by the Early Career Members and Chairs of the European Respiratory Society (ERS) Assembly 7: Paediatrics. We here summarise the highlights of the advances in paediatric respiratory research presented at the ERS International Congress 2022. The eight scientific groups of this Assembly cover a wide range of research areas, including respiratory physiology and sleep, asthma and allergy, cystic fibrosis (CF), respiratory infection and immunology, neonatology and intensive care, respiratory epidemiology, bronchology, and lung and airway developmental biology. Specifically, we report on abstracts presented at the congress on the effect of high altitude on sleep, sleep disorders, the hypoxic challenge test, and measurements of ventilation inhomogeneity. We discuss prevention of preschool wheeze and asthma, and new asthma medications. In children with CF, we describe how to monitor the effect of CF transmembrane conductance regulator modulator therapy. We present respiratory manifestations and chronic lung disease associated with common variable immunodeficiency. Furthermore, we discuss how to monitor respiratory function in neonatal and paediatric intensive care units. In respiratory epidemiology, we present the latest news from population-based and clinical cohort studies. We also focus on innovative and interventional procedures for the paediatric airway, such as cryotherapy. Finally, we stress the importance of better understanding the molecular mechanisms underlying normal and abnormal lung development.

Lung function after SARS-CoV-2 infection: A prospective cohort study in children.

INTRODUCTION: Although impaired lung function after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been described in adults, it is unclear whether lung function might be altered in children, especially among asymptomatic or mildly symptomatic patients. In this study, we report the results of lung function testing performed after SARS-CoV-2 infection in a large pediatric population. METHODS: The study included 589 patients with previous confirmed SARS-CoV-2 infection aged 0-18 years. Both symptomatic and asymptomatic patients during acute infection were enrolled in the study. A spirometry was performed in all cooperating patients. RESULTS: The mean age of enrolled patients was 9.6 years and the mean time from infection to enrollment was 171 days. Spirometry was performed and deemed evaluable in 433 patients. No patient had reduced forced vital capacity (FVC) and only 14 patients (3.2%) had a forced expiratory volume in the First second (FEV1) < 80%. The mean spirometry values recorded were in the normal range. There were no statistically significant differences in spirometry values between patients with respiratory symptoms during infection and those without. Similarly, there were no differences in spirometry parameters according to the time elapsed between infection and enrollment. CONCLUSION: Lung function, according to spirometry values, does not appear to be impaired long after infection in the pediatric population. The presence of respiratory symptoms during SARS-CoV-2 infection would not represent a risk factor for impaired lung function in this cohort of patients.

NRF2 Antioxidant Response and Interferon-Stimulated Genes Are Differentially Expressed in Respiratory-Syncytial-Virus- and Rhinovirus-Infected Hospitalized Children.

Respiratory diseases caused by respiratory syncytial virus (RSV) and human rhinovirus (HRV) are frequent causes of the hospitalization of children; nonetheless, RSV is responsible for the most severe and life-threatening illnesses. Viral infection triggers an inflammatory response, activating interferon (IFN)-mediated responses, including IFN-stimulated genes (ISG) expression with antiviral and immunomodulatory activities. In parallel, the reactive oxygen species (ROS) production activates nuclear factor erythroid 2-related factor 2 (NRF2), whose antioxidant activity can reduce inflammation by interacting with the NF-kB pathway and the IFN response. To clarify how the interplay of IFN and NRF2 may impact on clinical severity, we enrolled children hospitalized for bronchiolitis and pneumonia, and measured gene expression of type-I and III IFNs, of several ISGs, of NRF2 and antioxidant-related genes, i.e., glucose-6-phosphate dehydrogenase (G6PD), heme oxygenase 1 (HO1), and NAD(P)H dehydrogenase [Quinone] 1 (NQO1) in RSV- (RSV-A N = 33 and RSV-B N = 30) and HRV (N = 22)-positive respiratory samples. NRF2 and HO1 expression is significantly elevated in children with HRV infection compared to RSV (p = 0.012 and p = 0.007, respectively), whereas ISG15 and ISG56 expression is higher in RSV-infected children (p = 0.016 and p = 0.049, respectively). Children admitted to a pediatric intensive care unit (PICU) had reduced NRF2 expression (p = 0.002). These data suggest, for the first time, that lower activation of the NRF2 antioxidant response in RSV-infected infants may contribute to bronchiolitis severity.

Primary ciliary dyskinesia: A multicenter survey on clinical practice and patient management in Italy.

INTRODUCTION: There are no recent data on primary ciliary dyskinesia (PCD) distribution, diagnosis and treatment in Italy. METHODS: A descriptive study based on a survey questionnaire. It consisted of three sections (patients, diagnosis, and treatment), and sent to all the Italian PCD Centers. RESULTS: Questionnaires obtained from 20/22 centers in 12/20 regions showed that the total number of PCD patients treated at the participating centers was of 416. Out of all centers, 55% follow <20 patients, two centers have >40 patients, and 75% follow both pediatric and adults. Age at diagnosis was between 4 and 8 years in 45% of the centers, <3 years in three centers. Nasal nitric oxide, transmission electron microscopy and ciliary high-speed video microscopy are performed in 75%, 90%, and 40% of centers, respectively. Immunofluorescence is available in five centers. Genetic analysis is offered in 55% of the centers, and in seven centers >50% of the patients have a known genetic profile. Patients treated at all centers receive inhaled saline solutions, corticosteroids and chest physiotherapy. Prophylactic antibiotics and mucolytics are prescribed in 95% and 50% of the centers, respectively. Pseudomonas infection is treated with oral or inhaled antibiotics. CONCLUSIONS: Many Italian centers care for a small number of pediatric and adult patients, and diagnosis is often delayed. We found a great variability in the available diagnostic procedures, as well in the prescribed therapies. Our study will help to uniform diagnostic algorithm and share treatments protocols for PCD in Italy and allowed to set specific national goals.

Multicenter epidemiological investigation and genetic characterization of respiratory syncytial virus and metapneumovirus infections in the pre-pandemic 2018-2019 season in northern and central Italy.

Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) cause a high burden of disease, particularly in children and the elderly. With the aim to add knowledge on RSV and HMPV infections in Italy, a prospective, multicenter study was conducted by eight centers of the Working Group on Respiratory Virus Infections (GLIViRe), from December 2018-April 2019. Weekly distribution and patients' demographic and clinical data were compared in 1300 RSV and 222 HMPV-positive cases. Phylogenetic analysis of the G-glycoprotein coding region was performed to characterize circulating strains. RSV positivity ranged from 6.4% in outpatients of all ages to 31.7% in hospitalized children; HMPV positivity was 4-1.2% with no age-association. RSV season peaked in February and ended in mid-April: HMPV circulation was higher when RSV decreased in early spring. RSV was more frequent in infants, whereas HMPV infected comparatively more elderly adults; despite, their clinical course was similar. RSV-B cases were two-thirds of the total and had similar clinical severity compared to RSV-A. Phylogenetic analysis showed the circulation of RSV-A ON1 variants and the predominance of RSV-B genotype BA10. HMPV genotype A2c was the prevalent one and presented insertions of different lengths in G. This first multicenter Italian report on seasonality, age-specific distribution, and clinical presentation of RSV and HMPV demonstrated their substantial disease burden in young patients but also in the elderly. These data may provide the basis for a national respiratory virus surveillance network.

An overview on viral interference during SARS-CoV-2 pandemic.

Respiratory viruses represent the most frequent cause of mortality, morbidity and high healthcare costs for emergency visits and hospitalization in the pediatric age. Respiratory viruses can circulate simultaneously and can potentially infect the same host, determining different types of interactions, the so-called viral interference. The role of viral interference has assumed great importance since December 2019, when the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) came on the scene. The aim of this narrative review is to present our perspective regarding research in respiratory virus interference and discuss recent advances on the topic because, following SARS-CoV-2 restrictions mitigation, we are experimenting the co-circulation of respiratory viruses along with SARS-CoV-2. This scenario is raising many concerns about possible virus-virus interactions, both positive and negative, and the clinical, diagnostic and therapeutic management of these coinfections. Moreover, we cannot rule out that also climatic conditions and social behaviours are involved. Thus, this situation can lead to different population epidemic dynamics, including changes in the age of the targeted population, disease course and severity, highlighting the need for prospective epidemiologic studies and mathematical modelling able to predict the timing and magnitude of epidemics caused by SARS-CoV-2/seasonal respiratory virus interactions in order to adjust better public health interventions.

The non-functional ACE2 isoform, but not the SARS-CoV-2 receptor, is induced as an interferon-stimulated gene, in SARS-CoV-2 infected adults.

The recently discovered truncated, non-functional, ACE2 transcript (dACE2), but not the full-length ACE2 (f-lACE2), is induced by IFNs in differentiated airway cells. We measured expression of both ACE2 isoforms in SARS-CoV-2 positive and negative subjects, in relation to Interferon-stimulated genes. A significant activation of dACE2 transcript was found, in SARS-CoV-2 positive adults either hospitalized or not, showing a positive correlation with ISG15; f-lACE2 expression was weakly activated and not ISG-related. We confirmed a specific activation of dACE2 transcript in nasopharyngeal cells, related to the mucosal IFN response.

Comparison by Age of the Local Interferon Response to SARS-CoV-2 Suggests a Role for IFN-ε and -ω.

Children generally develop a mild disease after SARS-CoV-2 infection whereas older adults are at risk of developing severe COVID-19. Recent transcriptomic analysis showed pre-activated innate immunity in children, resulting in a more effective anti-SARS-CoV-2 response upon infection. To further characterize age-related differences, we studied type I and III interferon (IFN) response in SARS-CoV-2 infected and non-infected individuals of different ages. Specifically, levels of expression of type I (IFN-α, -ß, -ε and -ω), type III (IFN-λ1, -λ2 and -λ3) IFNs and of the IFN-stimulated genes, ISG15 and ISG56 were quantified in nasopharyngeal cells from diagnostic swabs. Basal transcription of type I/III IFN genes was highest among children and decreased with age. Among SARS-CoV-2-infected individuals, only IFN-ε and -ω levels were significantly higher in children and young adults whereas ISGs were overexpressed in infected adults. The occurrence of symptoms in children and the need for hospitalization in adults were associated to higher transcription of several IFN genes. Starting from a pre-activated transcription level, the expression of type I and III IFNs was not highly up-regulated in children upon SARS-CoV-2 infection; young adults activated IFNs' transcription at intermediate levels whereas older adults were characterized by higher ISGs and lower IFN-ε and -ω relative expression levels. Overall, our findings contribute to recognize components of a protective IFN response as a function of age, in the context of SARS-CoV-2 infection.

E-cigarettes and youth: an unresolved Public Health concern.

The use of electronic cigarettes (e-cigarette) and vaping devices started as a potential aid for cessation and reducing the harmful consequences of cigarette smoking, mainly in the adult population. Today e-cigarette use is highly increasing in vulnerable populations, especially young and pregnant women, due to the misconception of its harmless use.Despite the growing acknowledgment in e-cigarette as a potential harmful device, and due to mixed information found concerning its beneficial aid for smokers, along with an insufficient clinical study done in human models, it is important to further evaluate the possible benefits and risks of non-combusting, vaping nicotine or non-nicotine delivery devices.In this review we tried to summarize the latest updated information found in the literature, concentrating mainly in the variety of adverse effects of e-cigarette use and its contribution for recent and future health concerns.