Nonsense CD247 mutations show dominant-negative features in TCR expression and function.

BACKGROUND: The invariant TCRζ/CD247 homodimer is crucial for TCR/CD3 expression and signaling through its three immunoreceptor tyrosine-based activation motifs (ITAMs). Homozygous null mutations in CD247 lead to immunodeficiency, while carriers exhibit 50% reduced surface CD3. It is unclear whether carriers of other CD247 variants show dominant-negative effects. OBJECTIVE: To analyze and model the potential impact on TCR expression and function of heterozygous nonsense CD247 mutations found in patients with signs of immunodeficiency or autoimmunity. METHODS: Jurkat T cells, either wild-type (WT) or CRISPR/Cas9-edited CD247-deficient (ZKO), were lentivirally transduced with wild-type CD247 or mutations ablating one (Q142X), two (Q101X), or three (Q70X) ITAMs. RESULTS: Three patients from unrelated families were studied. Two heterozygous nonsense CD247 mutations were identified (p.Y152X and p.Q101X), which affected ITAM-3 and ITAM-2+3, respectively. Both mutations were associated with low surface CD3 expression, normal intracellular CD247 levels using a transmembrane-specific antibody but very low intracellular CD247 levels using an ITAM-3-specific one, suggesting the presence of truncated variants in T cells. Transduction of the mutations lacking 1, 2, or 3 ITAMs into ZKO could not restore normal surface CD3 expression (only 60%, 22% and 10%, respectively), whereas in WT they reduced it (to 39%, 19% and 9% of normal levels), and both effects were ITAM number dependent. All six transfectants showed reduced CD69 induction (25-50%), indicating that they were unable to signal downstream properly neither isolated nor associated with wild-type CD247. CONCLUSION: Our results suggest that CD247 variants lacking ITAMs due to nonsense, but not null, mutations are defective for normal TCR assembly and exert a dominant-negative effect on TCR expression and signaling in vitro. This, in turn, may correlate with clinical features in vivo.

Outcomes and impact of multidisciplinary team care on immunologic and hemato-oncologic pediatric patients.

INTRODUCTION: Immunologic and hemato-oncologic disorders in the pediatric population represent an interrelated and complex group of conditions whose approach, diagnosis, and management could be difficult. Multidisciplinary teams have been proved beneficial in treating such complexities. METHODS: We conducted a retrospective observational study at a tertiary hospital in Madrid, Spain, which is a pediatric immunology and onco-hematology referral center. We included all patients of multidisciplinary outpatient consultation, comprising a working group of pediatric oncohematologists and immunologists, between April 2016 and December 2019. Epidemiologic, clinical, and laboratory data were collected. We analyzed these data and established a relationship between age and findings of final diagnosis as well as variance on diagnoses prior to their multidisciplinary assessment and number of visits to the consultation. RESULTS: In all, 93 children and adolescents were included in this study. Laboratory abnormalities were the most frequent reason for being referred to our unit (87.2%); 78% of children had a previously diagnosed comorbidity. Before starting follow-up in the multidisciplinary consultation, 14% of patients were diagnosed, and after the study by the multidisciplinary team, the final diagnosis was reached in 58.1% of patients. No correlation was discovered between final diagnosis and gender (P = 0.29), age (biserial correlation coefficient, r = 0.036, P = 0.70), and number of visits (P = 0.07). CONCLUSION: A multidisciplinary approach to immunologic, hematologic, and oncologic pediatric diseases is feasible. It can be a powerful and useful tool for diagnosis and treatment, especially in complex pediatric patients.

Colchicine as rescue treatment in two pediatric patients with chronic recurrent multifocal osteomyelitis (CRMO).

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare idiopathic autoinflammatory bone disease characterised by noninfective inflammation of bones. Diagnostic approach is challenging and requires exclusion of other causes such as malignancies or infections. Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids are usually applied as first-line therapy in CRMO patients; however, some cases require more intensive therapy with second-line agents to control disease activity. We hereby describe the use of colchicine as a nonconventional second-line disease-modifying antirheumatic drug in two pediatric patients with CRMO refractory to NSAIDs and corticosteroids. Our data indicate that colchicine might prove an important area for future research as a potential therapeutic option with easy administration, low cost, and a good safety profile in CRMO patients refractory to first-line therapy.

Chronic Q Fever as Recurrent Osteoarticular Infection in Children: Case Report and Literature Review.

Q fever osteomyelitis has been rarely reported in children. This infection has an unclear pathophysiology and the optimal therapy is unknown. We report a 2-year-old girl with Coxiella burnetti recurrent multifocal osteomyelitis: femur, metatarsal, cuneiform, and calcaneus. We highlight the complicated diagnosis and management of this case and the importance of considering Q fever in children with chronic-recurrent multifocal osteomyelitis.

Colchicine treatment in children with periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome: A multicenter study in Spain.

OBJECTIVE: To evaluate the efficacy of colchicine therapy in pediatric patients with PFAPA syndrome who present with an incomplete response to the standard treatment or with frequent episodes (an interval of less than 14 days between two disease flares). METHODS: A multicenter cohort study of children diagnosed with PFAPA syndrome and treated with colchicine was performed in three separate hospitals located in Spain. The patients clinical and laboratory data were reviewed by accessing their medical records. Response to colchicine was evaluated after 12 months of treatment for frequency, duration, and intensity of PFAPA episodes. RESULTS: A total of 13 children were included in our study, 43% of whom were boys. Median age of the colchicine therapy initiation was 6 years (interquartile range (IQR)=3-9.5). Following a 12-month period of colchicine therapy (median dosage of 0.02 mg/kg/day; IQR=0.02-0.03), a significant decrease in the median number of flares (median 8; IQR=7-14 vs 3; IQR=2-4; p=0.005) and the duration of disease episodes (median 4 days; IQR=3.25-5.125 vs 1 day; IQR=1-2; p=0.003) was observed. Furthermore, the highest degree of fever during disease flares was reduced from median 40ºC (IQR=39.5-40) to 38.5ºC (IQR=37.7-38.9) (p=0.002). CONCLUSION: Colchicine therapy decreased the frequency and intensity of PFAPA. The use of colchicine could be an effective treatment in pediatric patients with PFAPA syndrome who present with frequent or severe relapses.

Immune dysregulation and Th2 polarization are associated with atopic dermatitis in heart-transplant children: A delicate balance between risk of rejection or atopic symptoms.

Atopic dermatitis (AD) has a high incidence in heart-transplant children, and the reason why there is more AD after transplantation is still unknown. We conducted a cross-sectional study comparing 11 AD and 11 non-AD age-matched heart-transplant children, to assess which immune alterations are related to AD in these patients. AD patients had been transplanted at a younger age compared to non-AD, indicating that age at transplant may be determinant in the onset of AD. The earlier thymectomy in AD heart-transplant children favored the presence of more differentiated phenotypes in the T cell compartment. We observed a clear reduction in the T-helper 1/T-helper 2 (Th1/Th2) ratio in AD children. This Th2 polarization was related to eosinophilia and high immunoglobulin E levels, but also to an impaired regulatory T cell (Treg) suppression, which could be secondary to an exhaustion of the Treg compartment. Interestingly, AD patients were free of rejection episodes (0/11) in comparison to non-AD children (4/11). We propose that a predominant Th2 phenotype may prevent the emergence of Th1 responses associated with graft rejection. A more differentiated Treg phenotype could also play a role in preventing acute rejection in the first year posttransplant. Our findings provide useful insights and knowledge for the better understanding of atopic disorders in transplanted children.