Combined deficient response to polysaccharide-based and protein-based vaccines predicts a severe clinical phenotype.

OBJECTIVES: Antibody response on polysaccharide- and protein-based vaccines is useful to test B cell functionality. As only few studies have explored the value of studying immune response to both vaccines, we evaluated the clinical value of anti-polysaccharide and anti-protein Luminex-based multiplex assays in context of primary immunodeficiency (PID) diagnosis. METHODS: A 10-plex Luminex-based assay detecting antibodies to ten pneumococcal polysaccharide (PnPS) serotypes [present in unconjugated Pneumovax, not in 13-valent pneumococcal conjugated vaccine (PCV)] and a 5-plex assay detecting antibodies to five protein antigens (present in DTap/Tdap) were clinically validated in healthy individuals (n=99) and in retrospective (n=399) and prospective (n=108) patient cohorts. Clinical features of individuals with impaired response to PnPS and/or proteins were compared to those with normal response. RESULTS: Antigen-specific antibody thresholds were determined in healthy individuals. Individuals with impaired anti-PnPS responses and deficient immunoglobulin levels suffered more from autoimmune diseases and had lower B cell levels compared to individuals with impaired anti-PnPS response with normal immunoglobulin levels. Individuals with combined impaired response to PnPS and proteins showed more severe clinical manifestations compared to individuals with isolated impaired response to PnPS or proteins. Eight of the 11 individuals with severely impaired responses to both PnPS and proteins had common variable immunodeficiency. Evaluation of the anti-PnPS response to four serotypes not contained in 20-valent PCV was comparable to evaluation to ten serotypes not contained in 13-valent PCV. CONCLUSIONS: Multiplexed assessment of anti-PnPS and anti-protein responses combined with immunoglobulin quantification provides useful clinical information to support PID diagnosis.

Spiroplasma infection as a cause of severe congenital keratouveitis, cataract and glaucoma.

BACKGROUND: Only seven cases of ocular Spiroplasma infection have been reported to date, all presenting as congenital cataracts with concomitant intraocular inflammation. We describe the first case of Spiroplasma infection initially presenting as a corneal infiltrate. CASE PRESENTATION: A 1-month-old girl was referred for a corneal infiltrate in the left eye. She presented in our hospital with unilateral keratouveitis. Examination showed a stromal corneal infiltrate and dense white keratic precipitates in the left eye. Herpetic keratouveitis was suspected and intravenous acyclovir therapy was initiated. Two weeks later, the inflammation in the left eye persisted and was also noticed in the right eye. Acute angle-closure glaucoma and a cataract with dilated iris vessels extending onto the anterior lens capsule developed in the left eye. The inflammation resolved after treatment with azithromycin. Iridectomy, synechiolysis and lensectomy were performed. Bacterial metagenomic sequencing (16 S rRNA) and transmission electron microscopy revealed Spiroplasma ixodetis species in lens aspirates and biopsy. Consequently, a diagnosis of bilateral Spiroplasma uveitis was made. CONCLUSIONS: In cases of congenital cataract with concomitant intraocular inflammation, Spiroplasma infection should be considered. The purpose of this case report is to raise awareness of congenital Spiroplasma infection as a cause of severe keratouveitis, cataract and angle-closure glaucoma in newborns. Performing molecular testing on lens aspirates is essential to confirm diagnosis. Systemic macrolides are suggested as the mainstay of treatment.

The burden and surveillance of RSV disease in young children in Belgium-expert opinion.

Infections with respiratory syncytial virus (RSV) can cause severe disease. In young children, RSV is the most common cause of lower respiratory tract illness and life-threatening infections most commonly occur in the first years of life. In adults, elderly and immunocompromised people are most vulnerable. Recently there has been an acceleration in the development of candidate RSV vaccines, monoclonal antibodies and therapeutics which are expected to become available in Europe within the next 2-10 years. Understanding the true burden of childhood RSV disease will become very important to support public health authorities and policy makers in the assessment of new therapeutic opportunities against RSV disease. A systematic literature search was performed to map local data on the burden of RSV disease and to evaluate available RSV surveillance systems. A group of 9 paediatric infectious diseases specialists participated in an expert panel. The purpose of this meeting was to evaluate and map the burden associated with RSV infection in children, including patient pathways and the epidemiological patterns of virus circulation in Belgium. Sources of information on the burden of RSV disease in Belgium are very limited. For the outpatient setting, it is estimated that 5-10% of young patients seen in primary care are referred to the hospital. Around 3500 children between 0 and 12 months of age are hospitalized for RSV-bronchiolitis every year and represent the majority of all hospitalizations. The current Belgian RSV surveillance system was evaluated and found to be insufficient. Knowledge gaps are highlighted and future perspectives and priorities offered. CONCLUSION: The Belgian population-based RSV surveillance should be improved, and a hospital-led reporting system should be put in place to enable the evaluation of the true burden of RSV disease in Belgium and to improve disease management in the future. WHAT IS KNOWN: • RSV bronchiolitis is a very important cause of infant hospitalization. • The burden of disease in the community is poorly studied and underestimated. WHAT IS NEW: • This expert opinion summarizes knowledge gaps and offers insights that allow improvement of local surveillance systems in order to establish a future-proof RSV surveillance system.

Defining Polysaccharide Antibody Deficiency: Measurement of Anti-Pneumococcal Antibodies and Anti-Salmonella typhi Antibodies in a Cohort of Patients with Recurrent Infections.

BACKGROUND: The correlation between different methods for the detection of pneumococcal polysaccharide vaccine (PPV) responses to diagnose specific polysaccharide antibody deficiency (SAD) is poor and the criteria for defining a normal response lack consensus. We previously proposed fifth percentile (p5) values of PPV responses as a new cutoff for SAD. OBJECTIVE: To analyze the association of SAD (determined by either World Health Organization (WHO)-standardized ELISA or multiplex bead-based assay) with abnormal response to Salmonella (S.) typhi Vi vaccination in a cohort of patients with recurrent infections. METHODS: Ninety-four patients with a clinical history suggestive of antibody deficiency received PPV and S. typhi Vi vaccines. Polysaccharide responses to either 3 or 18 pneumococcal serotypes were measured by either the WHO ELISA or a multiplex in-house bead-based assay. Anti-S. typhi Vi IgG were measured by a commercial ELISA kit. Allohemagglutinins (AHA) were measured by agglutination method. RESULTS: Based on the American Academy of Allergy, Asthma and Immunology (AAAAI) criteria for WHO ELISA, 18/94 patients were diagnosed with SAD and 22/93 based on serotype-specific p5 cutoffs for bead-based assay. The association between the two methods was significant, with 10 subjects showing abnormal response according to both techniques. Abnormal response to S. typhi Vi vaccination was found in 7 patients, 6 of which had SAD. No correlation was found between polysaccharide response and AHA, age, or clinical phenotype. CONCLUSION: The lack of evidence-based gold standards for the diagnosis of SAD represents a challenge in clinical practice. In our cohort, we confirmed the insufficient correlation between different methods of specific PPV response measurement, and showed that the S. typhi Vi response was not contributive. Caution in the interpretation of results is warranted until more reliable diagnostic methods can be validated.

PID in Disguise: Molecular Diagnosis of IRAK-4 Deficiency in an Adult Previously Misdiagnosed With Autosomal Dominant Hyper IgE Syndrome.

Autosomal recessive IL-1R-associated kinase 4 (IRAK-4) deficiency is a rare cause of recurrent pyogenic infections with limited inflammatory responses. We describe an adult female patient with severe lung disease who was phenotypically diagnosed as suffering from autosomal dominant Hyper IgE syndrome (AD HIES) because of recurrent skin infections with Staphylococcus aureus, recurrent pneumonia and elevated serum IgE levels. In contrast to findings in AD HIES patients, no abnormalities were found in the Th17 and circulating follicular helper T cell subsets. A panel-based sequencing approach led to the identification of a homozygous IRAK4 stop mutation (c.877C > T, p.Gln293*).

Lower physical activity levels in youth with Cystic Fibrosis compared to healthy controls: A multicentre comparative study.

BACKGROUND: Regular physical activity (PA) offers significant health benefits on both short (i.e., emotional well-being) and long term (i.e., fewer hospitalizations) in Youth with Cystic Fibrosis (YwCF). Regardless, evidence on PA levels in YwCF compared to healthy controls (HC) is inconsistent. Additionally, PA is a multidimensional outcome influenced by several factors such as Quadriceps strength and functional performance. Therefore, we aimed to assess whether PA, Quadriceps strength and functional performance differ between YwCF and HC across different age groups (i.e., children and adolescents). METHODS: YwCF aged 6-17 from two Belgian CF centres and age- and sex-matched HC were recruited. PA was measured with an ActiGraph GT3X + BT during 7 consecutive days. Isometric Quadriceps strength was assessed with a Hand Held Dynamometer and functional performance with a sit-to stand test (STS) and standing long jump (SLJ). RESULTS: A total of 49 YwCF (44 % male; 11.3 ± 3.3 years) and 49 HC (48 % male; 11.9 ± 3.5 years) were included. On average days, YwCF performed 4 ± 6.4 min less light PA and 7.5 ± 6.7 min less moderate-to-vigorous PA compared to HC (p = 0.04; p = 0.01). The differences in moderate-to-vigorous PA seem more pronounced in children (6-11 years)(p = 0.04). Furthermore, YwCF had similar Quadriceps strength to HC but had lower scores on the STS and SLJ (p = 0.50, p = 0.08; p = 0.02). CONCLUSIONS: This study shows lower PA levels and functional performance for YwCF, indicating that there is an urgent need for interventions promoting PA in YwCF. PA promotion will become increasingly important in the post modulator area to prevent health risks associated with low PA.

Misdiagnosis as asphyxiating thoracic dystrophy and CMV-associated haemophagocytic lymphohistiocytosis in Shwachman-Diamond syndrome.

Shwachman-Diamond syndrome (SDS) is an autosomal recessive disorder characterised by skeletal dysplasia, exocrine pancreatic insufficiency and bone marrow failure. Various other conditions, such as hepatopathy and failure to thrive have been associated with SDS. A retrospective study was conducted to describe mutations, clinical features, and the immunological profile of 11 Belgian patients with genetically confirmed diagnosis of SDS. This study confirms the existing understanding of the classical features of SDS although the typical triad was present in only six out of nine fully studied patients. The following important observations are made in this cohort. Four out of eleven patients were misdiagnosed as having Asphyxiating Thoracic Dystrophy (Jeune syndrome) because of severe thoracic dystrophy. Another two patients presented with unexplained episodes of symptomatic hypoglycaemia. The immunological phenotype was heterogeneous although laboratory abnormalities were noticed in eight out of ten patients assessed. Three patients experienced a life threatening viral infection (respiratory syncytial virus, cytomegalovirus (CMV) and rotavirus). In one patient, CMV infection caused an episode of haemophagocytic lymphohistiocytosis. One patient has bronchiectasis at the age of 3 years due to recurrent respiratory tract infections. These findings strengthen the suspicion of an abnormal immune system in SDS. Liver anomalies, usually described as benign and transitory in SDS patients, were severe in two patients of the cohort. One patient developed hepatopulmonary syndrome. The findings in this national cohort of SDS patients could contribute to the prevention of misdiagnosis in the future and enable more rapid recognition of certain severe complications.

Anterior and posterior tracheopexy for severe tracheomalacia.

Objectives: Congenital tracheomalacia can be the cause of respiratory failure in young children. Although the indication for surgical treatment has already been discussed vigorously, no clear guidelines about the modality are available. Methods: Through a sternotomy approach, a combination of posterior pexy and anterior tracheopexy using a tailored ringed polytetrafluoroethylene prosthesis is performed. Patient demographic characteristics, as well as operative details and postoperative outcomes, are included in the analysis. Results: Between 2018 and 2022, 9 children underwent the operation under review. All patients showed severe clinical symptoms of tracheomalacia, which was confirmed on bronchoscopy. The median age was 9 months. There was no operative mortality. Eight patients could be weaned from the ventilator. One patient died because of interstitial lung disease with bronchomalacia and concomitant severe cardiac disease. The longest follow-up now is 4 years, and shows overall excellent clinical results, without any reintervention. Conclusions: Surgical treatment of tracheomalacia through a combination of posterior and anterior pexy is feasible, with acceptable short- and midterm results.

Physical activity and its correlates in people with cystic fibrosis: a systematic review.

Cystic fibrosis (CF) is a life-shortening genetic disease, affecting multiple life domains including physical activity (PA). Although higher PA levels are associated with multiple health benefits, little insight exists on the PA level of people with CF (PwCF) compared to healthy peers. Evidence on the influencing factors (i.e. correlates) of PA in this clinical population is scarce, but essential to fully understand their PA behaviour. Therefore, the present review aims to provide an overview of the PA level of PwCF compared to healthy peers, and the correlates of PA in PwCF. A systematic search of three databases resulted in 46 included studies. Analysis of 16 studies showed that the CF population is equally active compared to healthy peers, but there is a trend towards less high-intensity PA in youths with CF. Furthermore, PA is positively associated with quality of life, lung function, (maximal) exercise capacity, bone mineral density and quadriceps force. Also, PA was lower on weekdays compared to weekend days and lower when experiencing pulmonary exacerbations. More high-quality research is required in PwCF, particularly longitudinal studies that further explore the correlates of PA, with PA investigated as a primary outcome and measured objectively.

Urinary sodium/creatinine ratio is a predictor for fractional sodium excretion and related to age in patients with cystic fibrosis.

Electrolyte disturbances are common in patients with cystic fibrosis (CF). Current guidelines on monitoring sodium status are based on research in a small group of infants and require blood sampling. The aim of this study was to evaluate urinary salt parameters as a surrogate for sodium-status in different age-groups. Blood and urine samples for electrolytes were collected from 222 patients followed at the Ghent University Hospital CF-center. Fractional sodium excretion (FENa) and several urinary parameters were calculated. Clinical characteristics did not differ according to sodium status, defined as FENa <0.5%. ROC analysis demonstrated that sodium/creatinine ratio (UNa/Creat) predicted the sodium status most accurately with high sensitivity and specificity (97 and 91% respectively). The UNa/Creat cut-off predicting a FENa <0.5% differed significantly according to age. The UNa/Creat is an excellent marker for the sodium status defined as a FENa <0.5%. However, different cut-offs according to age category should be applied.

Liver transplantation for very severe hepatopulmonary syndrome due to vitamin A-induced chronic liver disease in a patient with Shwachman-Diamond syndrome.

Vitamin A intoxication is a rare cause of liver disease, but the risk increases in patients with underlying liver dysfunction. We present a patient with Shwachman-Diamond Syndrome who developed liver fibrosis, portal hypertension and very severe hepatopulmonary syndrome as a consequence of chronic vitamin A intoxication. She underwent successful liver transplantation with complete resolution of the pulmonary shunting.

Fifth Percentile Cutoff Values for Antipneumococcal Polysaccharide and Anti-Salmonella typhi Vi IgG Describe a Normal Polysaccharide Response.

BACKGROUND: Serotype-specific antibody responses to unconjugated pneumococcal polysaccharide vaccine (PPV) evaluated by a World Health Organization (WHO)-standardized enzyme-linked immunosorbent assay (ELISA) are the gold standard for diagnosis of specific polysaccharide antibody deficiency (SAD). The American Academy of Allergy, Asthma and Immunology (AAAAI) has proposed guidelines to interpret the PPV response measured by ELISA, but these are based on limited evidence. Additionally, ELISA is costly and labor-intensive. Measurement of antibody response to Salmonella typhi (S. typhi) Vi vaccine and serum allohemagglutinins (AHA) have been suggested as alternatives. However, there are no large cohort studies and cutoff values are lacking. OBJECTIVE: To establish cutoff values for antipneumococcal polysaccharide antibody response, anti-S. typhi Vi antibody, and AHA. METHODS: One hundred healthy subjects (10-55 years) were vaccinated with PPV and S. typhi Vi vaccine. Blood samples were obtained prior to and 3-4 weeks after vaccination. Polysaccharide responses to 3 serotypes were measured by WHO ELISA and to 12 serotypes by an in-house bead-based multiplex assay. Anti-S. typhi Vi IgG were measured with a commercial ELISA kit. AHA were measured by agglutination method. RESULTS: Applying AAAAI criteria, 30% of healthy subjects had a SAD. Using serotype-specific fifth percentile (p5) cutoff values for postvaccination IgG and fold increase pre- over postvaccination, only 4% of subjects had SAD. One-sided 95% prediction intervals for anti-S. typhi Vi postvaccination IgG (≥11.2 U/ml) and fold increase (≥2) were established. Eight percent had a response to S. typhi Vi vaccine below these cutoffs. AHA titer p5 cutoffs were ½ for anti-B and » for anti-A. CONCLUSION: We establish reference cutoff values for interpretation of PPV response measured by bead-based assay, cutoff values for S. typhi Vi vaccine responses, and normal values for AHA. For the first time, the intraindividual consistency of all three methods is studied in a large cohort.

Olmsted syndrome: exploration of the immunological phenotype.

BACKGROUND: Olmsted syndrome is a rare congenital skin disorder presenting with periorifical hyperkeratotic lesions and mutilating palmoplantar keratoderma, which is often associated with infections of the keratotic area. A recent study identified de novo mutations causing constitutive activation of TRPV3 as a cause of the keratotic manifestations of Olmsted syndrome. METHODS: Genetic, clinical and immunological profiling was performed on a case study patient with the clinical diagnosis of Olmsted syndrome. RESULTS: The patient was found to harbour a previously undescribed 1718G-C transversion in TRPV3, causing a G573A point mutation. In depth clinical and immunological analysis found multiple indicators of immune dysregulation, including frequent dermal infections, inflammatory infiltrate in the affected skin, hyper IgE production and elevated follicular T cells and eosinophils in the peripheral blood. CONCLUSIONS: These results provide the first comprehensive assessment of the immunological features of Olmsted syndrome. The systemic phenotype of hyper IgE and persistent eosinophilia suggest a primary or secondary role of immunological processes in the pathogenesis of Olmsted syndrome, and have important clinical consequences with regard to the treatment of Olmsted syndrome patients.