Immune profiling and functional analysis of NK and T cells in ataxia telangiectasia.

Ataxia telangiectasia (AT) is a rare autosomal-recessive disorder characterized by profound neurodegeneration, combined immunodeficiency, and an increased risk for malignant diseases. Treatment options for AT are limited, and the long-term survival prognosis for patients remains grim, primarily due to the emergence of chronic respiratory pathologies, malignancies, and neurological complications. Understanding the dysregulation of the immune system in AT is fundamental for the development of novel treatment strategies. In this context, we performed a retrospective longitudinal immunemonitoring of lymphocyte subset distribution in a cohort of AT patients (n = 65). Furthermore, we performed FACS analyses of peripheral blood mononuclear cells from a subgroup of 12 AT patients to examine NK and T cells for the expression of activating and functional markers. We observed reduced levels of peripheral blood CD3+CD8+ cytotoxic T cells, CD3+CD4+ T helper cells, and CD19+ B cells, whereas the amount of CD3--CD56+ NK cells and CD3+CD56+ NKT-like cells was similar compared with age-matched controls. Notably, there was no association between the age-dependent kinetic of T-, B-, or NK-cell counts and the occurrence of malignancy in AT patients. Additionally, our results indicate an altered NK- and T-cell response to cytokine stimulation in AT with increased levels of TRAIL, FasL, and CD16 expression in NK cells, as well as an elevated activation level of T cells in AT with notably higher expression levels of IFN-γ, CD107a, TRAIL, and FasL. Together, these findings imply function alterations in AT lymphocytes, specifically in T and NK cells, shedding light on potential pathways for innovative therapies.

Genotoxicity Associated with Retroviral CAR Transduction of ATM-Deficient T Cells.

Somatic variants in DNA damage response genes such as ATM are widespread in hematologic malignancies. ATM protein is essential for double-strand DNA break repair. Germline ATM deficiencies underlie ataxia-telangiectasia (A-T), a disease manifested by radiosensitivity, immunodeficiency, and predisposition to lymphoid malignancies. Patients with A-T diagnosed with malignancies have poor tolerance to chemotherapy or radiation. In this study, we investigated chimeric antigen receptor (CAR) T cells using primary T cells from patients with A-T (ATM-/-), heterozygote donors (ATM+/-), and healthy donors. ATM-/- T cells proliferate and can be successfully transduced with CARs, though functional impairment of ATM-/- CAR T-cells was observed. Retroviral transduction of the CAR in ATM-/- T cells resulted in high rates of chromosomal lesions at CAR insertion sites, as confirmed by next-generation long-read sequencing. This work suggests that ATM is essential to preserve genome integrity of CAR T-cells during retroviral manufacturing, and its lack poses a risk of chromosomal translocations and potential leukemogenicity. Significance: CAR T-cells are clinically approved genetically modified cells, but the control of genome integrity remains largely uncharacterized. This study demonstrates that ATM deficiency marginally impairs CAR T-cell function and results in high rates of chromosomal aberrations after retroviral transduction, which may be of concern in patients with DNA repair deficiencies.

Absence of ATM leads to altered NK cell function in mice.

Ataxia-telangiectasia (A-T) is a rare disorder caused by genetic defects of A-T mutated (ATM) kinase, a key regulator of stress response, and characterized by neurodegeneration, immunodeficiency, and high incidence of cancer. Here we investigated NK cells in a mouse model of A-T (Atm-/-) showing that they are strongly impaired at killing tumor cells due to a block of early signaling events. On the other hand, in Atm-/- littermates with thymic lymphoma NK cell cytotoxicity is enhanced as compared with ATM-proficient mice, possibly via tumor-produced TNF-α. Results also suggest that expansion of exhausted NKG2D+ NK cells in Atm-/- mice is driven by low-level expression of stress-inducible NKG2D ligands, whereas development of thymoma expressing the high-affinity MULT1 ligand is associated with NKG2D down-regulation on NK cells. These results expand our understanding of immunodeficiency in A-T and encourage exploring NK cell biology in A-T patients in the attempt to identify cancer predictive biomarkers and novel therapeutic targets.

Causative mechanisms and clinical impact of immunoglobulin deficiencies in ataxia telangiectasia.

BACKGROUND: Ataxia telangiectasia (AT) is characterized by cerebellar ataxia, telangiectasia, immunodeficiency, and increased cancer susceptibility and is caused by mutations in the ataxia telangiectasia mutated (ATM) gene. The immunodeficiency comprises predominantly immunoglobulin deficiency, mainly IgA and IgG2, with a variable severity. So far, the exact mechanisms underlying the immunoglobulin deficiency, especially the variable severity, remain unelucidated. OBJECTIVE: We characterized the clinical impact of immunoglobulin deficiencies in AT and elucidated their mechanisms in AT. METHODS: We analyzed long-term immunoglobulin levels, immunophenotyping, and survival time in our cohort (n = 87, median age 16 years; maximum 64 years). Somatic hypermutation and class-switch junctions in B cells were analyzed by next-generation sequencing. Furthermore, an in vitro class-switching induction assay was performed, followed by RNA sequencing, to assess the effect of ATM inhibition. RESULTS: Only the hyper-IgM AT phenotype significantly worsened survival time, while IgA or IgG2 deficiencies did not. The immunoglobulin levels showed predominantly decreased IgG2 and IgA. Moreover, flow cytometric analysis demonstrated reduced naive B and T lymphocytes and a deficiency of class-switched IgG2 and IgA memory B cells. Somatic hypermutation frequencies were lowered in IgA- and IgG2-deficient patients, indicating hampered germinal center reaction. In addition, the microhomology of switch junctions was elongated, suggesting alternative end joining during class-switch DNA repair. The in vitro class switching and proliferation were negatively affected by ATM inhibition. RNA sequencing analysis showed that ATM inhibitor influenced expression of germinal center reaction genes. CONCLUSION: Immunoglobulin deficiency in AT is caused by disturbed development of class-switched memory B cells. ATM deficiency affects both germinal center reaction and choice of DNA-repair pathway in class switching.

B-cell subsets imbalance and reduced expression of CD40 in ataxia-telangiectasia patients

BACKGROUND: Ataxia-telangiectasia (AT) is a well-known primary immunodeficiency with recurrent sinopulmonary infections and variable abnormalities in both the humoral and cellular immune system. Dysfunctions in immunoglobulin production, reduced number of B cells, and B-cell receptor excision circles copies have been reported. We aimed to understand the immunological mechanisms involving the humoral compartment in AT patients by analysing peripheral blood B cells subsets, B-T lymphocyte cooperation through the expression of CD40 and CD40 ligand (CD40L), and cytokines involved in class-switch recombination production. METHODS: We compared the proportion of B-cell subsets, the expression of CD40/CD40L, and the plasma levels of IL-6 and IFN-gamma of 18 AT patients and 15 healthy age-sex-matched controls using flow cytometry. RESULTS: We found that some steps in peripheral B cell development were altered in AT with a pronounced reduction of cell-surface CD40 expression. The proportions of transitional and naïve-mature B cells were reduced, whereas CD21-low, natural effector memory, IgM-only memory, and IgG atypical memory B cells were present in a higher proportion. CONCLUSIONS: These findings revealed a disturbed B-cell homeostasis with unconventional maturation of B lymphocyte memory cells, which can explain the consequent impairment of humoral immunity

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Comparison of major lymphocyte subpopulations and recent thymic emigrants in patients with ataxia telangiectasia and age-matched healthy groups

BACKGROUND: Ataxia telangiectasia (A-T) is a genetic disorder caused by the homozygous mutation of the A-T mutated gene. It is frequently associated with variable degrees of cellular and humoral immunodeficiency. However, the immune defects in A-T patients are not well characterized. To the best of our knowledge, no studies have focused on the major lymphocyte subpopulations and recent thymic emigrants of A-T patients in comparison with age-matched healthy controls. METHODS: Following the European Society for Immunodeficiencies criteria, 17 patients diagnosed with A-The, and 12 age-matched healthy children were assigned to the study. Both patients and healthy controls were grouped as 1-5, 6-10, 11-15, and 15+ years. By using a flow cytometer, major lymphocyte subpopulations and CD4+CD45RA+CD31+ recent thymic emigrants were determined as percentage and absolute cell numbers and compared. RESULTS: No significant differences in all lymphocyte subpopulations were observed between the age groups of A-T patients. Compared to the healthy controls, there was a decrease in T cells, effector memory T4 cells, B cells, naïve B cells, naïve T4 cells, switched B cells, and recent thymic emigrants and an increase in active T8 cells and non-switched B cells in the percentage and absolute number of some cell populations in the A-T group. CONCLUSIONS: This study showed that effector functions in some cell lymphocyte populations were decreased in A-T patients

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Inmunodeficiencia con ataxia telangiectasia. Reporte de un caso / Immunodeficiency with ataxia telangiectasia. Case report

La Ataxia Telangiectasia (AT) es un síndrome multisistémico complejoque se hereda de forma autosómica recesiva y está incluida dentro de lossíndromes genéticos de inestabilidad cromosómica. Las mutaciones en el genATM (ataxia telangiectasia mutado) son la causa de la aparición de la AT. Lasusceptibilidad a las infecciones recurrentes o persistentes de severidad variable es una característica principal en el 70 % de los individuos con AT y sondebidos en parte a la inmunodeficiencia observada en estos pacientes. La ATes un trastorno muy raro incluido en los síndromes de InmunodeficienciaPrimaria. Este ocurre con una frecuencia de 1 caso por 40 a 100 000 nacidosen el mundo, con prevalencia de portadores de 1.4-2%. Se presenta un paciente masculino de 10 años de edad, en el que a los 2 años de edad, se constatóataxia de tronco y de la marcha, hipotonía muscular generalizada y disartria.El paciente también desarrolló en piel y mucosas hiperpigmentación e hipopigmentación. A los 3 años de edad aparecieron telangiectasias oculocutá-neas y se detectaron nistagmos a los 6 años y 10 meses de edad. Por otra parte,comenzó a presentar episodios frecuentes de infecciones respiratorias altasy bajas: rinitis purulenta, sinusitis maxilar, y bronconeumonías tan bien comogiardiasis. Los estudios inmunológicos a los 2 años de edad revelaron unadisminución de las concentraciones séricas de IgG, IgA, e IgM aumentada;niveles bajos de IgE y elevados de ·-fetoproteína. La RMN a los 7 años deedad mostró una atrofia cerebelosa. Los linfocitos T CD2+ CD8+ estaban disminuidos. El paciente fue tratado con gammaglobulina, dieta balanceada yvitaminoterapia con evolución satisfactoria a pesar del pronóstico reservadode este síndrome que se caracteriza por neurodegeneración progresiva (AU)

Ataxia telangiectasia (AT) is a multisystemic complex syndrome thatis typically transmitted in an autosomal recessive mode of inheritance andit is included among chromosomal breakage syndromes. The mutationson Ataxia-telangiectasia mutated (ATM) gen are the cause of AT disease.The risk to recurrent infection, with variable severity, is observed in 70percent of these patients and it is attributed to their immunodeficiency.AT is a very rare disorder included in the Primary ImmunodeficiencySyndromes. It occurs at a frequency of 1 case per 40 to 100,000 births worldwide with an estimated frequency of carriers of 1.4-2%. We present a caseof a ten year- old male who had a past personal history of truncal andwalking ataxia, generalized muscular hypotonia, and dysarthria beginning at age two. He also developed hyper and hypopigmentation in theskin and mucosa. At the age of three, an oculo-cutaneous telangiectasiaappeared and nystagmus was found when he was six years and ten monthsold. On the other hand, he also began to suffer frequent episodes of infections of the upper and the lower respiratory tracts including: purulentrhinitis, maxilar sinusitis and bronchopneumonias as well as giardhiasis.Immunologic studies at the age of two revealed a decrease of the sericconcentrations of IgG, IgA, high IgM values; low levels of IgE and highlevels of alpha-fetoprotein. At seven, the MRI showed cerebellar atrophy.The amount of CD2+ CD8+ T lymphocytes was diminished. The patientwas treated with gammaglobulin, balanced diet and vitamin therapy withsatisfactory evolution in spite of the reserved prognosis for this syndrome that is characterized by a progressive neurodegeneration (AU)

Response to polysaccharide antigens in patients with ataxia-telangiectasia

OBJECTIVE: To analyze the production of antibodies to polysaccharide antigens in patients with ataxia-telangiectasia.PATIENTS AND METHODS: We used the ELISA technique to measure the levels of IgG antibodies to serotypes 1, 3, 5, 6B, 9V and 14 of Streptococcus pneumoniae in 14 patients with ataxia-telangiectasia before and after immunization with 23-valent polysaccharide vaccine. Adequate response to individual polysaccharide can be defined as a postimmunization antibody titer equal to or greater than 1.3 µg/ml or as a minimum fourfold increase over the baseline (preimmunization) value. RESULTS: Six (43%) patients showed an absent response to all serotypes analyzed. Four patients showed adequate response to only one serotype, one patient to two serotypes, two patients to three serotypes and only one patient to four out of six serotypes analyzed. No patient had adequate response to all serotypes tested. Postimmunization pneumococcus IgG levels were higher than preimmunization levels to all serotypes analyzed, except for serotype 3. In spite of this, the mean postimmunization levels were lower than 1.3 µg/ml in all serotypes, except for serotype 14. Mean increment was less than four in all serotypes analyzed. CONCLUSION: Our results suggest that patients with ataxia-telangiectasia are at a high risk of having an impaired response to pneumococcus, which may be one of the causes of recurrent sinopulmonary infections in these patients.

Diferent clinical and laboratory evolutions in ataxia-telangiectasia syndrome: report of four cases

We report four patients with ataxia-telangiectasia syndrome that presented varied neurologic evolution. Three patients initially presented neurologic alterations of slow progression, evolving to late immunocompromised conditions. The fourth patient presented, from symptom onset, immune and neurologic debilitation, that were both severe and of fast progression. The chronological sequence of the most commonly observed immunocompromised conditions were in our patients, in ascending order, IgA deficiency, IgG2 deficiency and the neutrophil phagocytosis stage and common variable immunodeficiency. The first two reports are of sisters in whom the diagnosis was done between the ages of three and six years, having ocular apraxia, cerebellar ataxia and telangiectasia. Slow progression of neurologic debilitation was observed, without presentation of intermittent infections. The patients began presenting accentuated immunocompromised conditions at the ages of 14 and 17 years, dying at the ages of 16 and 20 years, respectively, due to severe infections that were resistant to treatment. The diagnosis of the third case was established when the patient was two years old, presenting ataxia and telangiectasia. Syndrome progression was slow, presenting at the age of eight years more accentuated neurologic disorders and IgA deficiency. The fourth case presented significant neurologic compromise at the age of five, simultaneous to IgA and IgG2 deficiency, and repeating pneumonias and sinusitis. At this time, intravenous gammaglobulin reposition was done. The neurologic and immune disorders progressed rapidly, and at the age of eight presented the inability to walk. At this time inversion of the CD4/CD8 ration was verified through laboratory tests

Se presentan cuatro pacientes portadores del síndrome de ataxia telangiectasia que tuvieron diferente evolución neurológica y inmunológica. Tres pacientes empezaron el cuadro clínico con alteraciones neurológicas de progresión lenta y compromiso inmunológico tardío. La cuarta paciente desde el inicio presentó alteraciones inmunológicas y neurológicas graves y de rápida progresión. La secuencia cronológica de las alteraciones inmunológicos más observadas fue la siguiente: 1.º deficiencia de IgA; 2.º deficiencia de IgG2 y de la etapa de acción fagocítica de los neutrófilos; 3.º inmunodeficiencia común variable. Los dos primeros casos son dos hermanas en las que el diagnóstico fue hecho a los tres y seis años de edad, observándose apraxia ocular, ataxia cerebelar y telangiectasias. Hubo progresión lenta del cuadro neurológico, sin infecciones paralelas. Las pacientes empezaron a presentar alteración inmunológica acentuada a los 17 y 14 años, falleciendo a los 20 y 16 años respectivamente, por infecciones graves y resistentes al tratamiento. El diagnóstico del tercer caso fue establecido a los dos años de edad con la presencia de ataxia y telangectasias. La progresión del síndrome fue lenta, presentando trastornos neurológicos más acentuados y deficiencia de IgA a los ocho años de edad. La cuarta paciente presentó un importante compromiso neurológico a los cinco años de edad, simultáneamente a la deficiencia de IgA e IgG2, sinusitis y neumonías de repetición. En esa ocasión fue iniciada reposición de gammaglobulina endovenosa. Los trastornos neurológicos e inmunológicos progresaron rápidamente, observándose incapacidad de marcha e inversión de la relación CD4/CD8 a los ocho años de edad

Inmunodeficiencia con ataxia telangiectasia: presentación de 4 casos / Immunodeficiency with ataxia telangiectasia: report of 4 cases

Se presentan 4 pacientes con síntomas y signos propios de una inmunodeficiencia con ataxia telangiectasia, tanto desde el punto de vista clínico como de los marcadores serológicos y celulares. En todos los casos la ataxia se evidenció cuando los pacientes comenzaron a caminar, las telangiectasias tuvieron una aparición más tardía y las infecciones fueron manifiestas desde edades muy tempranas. Los defectos inmunológicos fueron heterogéneos, tanto de células B como T. Todos los pacientes se encuentran actualmente bajo tratamiento inmunoestimulante a pesar de lo cual mantienen cuadros infecciosos frecuentes. La enfermedad neurológica progresa. Se recomienda el seguimiento estrecho de los casos por la posible aparición de complicaciones graves como enfermedad pulmonar crónica o neoplasias linforreticulares(AU)

Detección de heterocigotos de ataxia telangiectasia por la sensibilidad a la radiación ionizante / Detection of heterocygotic with patients with ataxia telangiectasia show chromosomic rupture

Investigaciones recientes han demostrado que los pacientes homocigotos y heterocigotos de ataxia telangiectasia (AT) tienen rompimientos cromosómicos. De acuerdo con esta característica se diseñó el estudio inducido rompimientos cromosómicos en células granulocíticas de pacientes con diagnóstico de AT, heterocigotos obligados de AT y comparados con un grupo de individuos sanos. A todos los pacientes se les cuantificó el número de rompimientos cromosómicos con 14 dosis de radiación 125 kv, 125 mA. Los resultados sugieren diferencias significativas en el número de alteraciones estructurales cromosómicas inducidas por la radiación en los granulocitos de heterocigotos de ataxia telangiectasia similares a las alteraciones estructurales de los linfocitos de pacientes con AT y se demuestra que estas alteraciones se presentan preferentemente en un cromosoma del grupo C de homocigotos y heterocigotos de AT

Primary immunodeficiency diseases: a presentation of 6 cases

The peripheral blood leukocytes of 6 children with clinical data suggestive of primary cellular immunodeficiencies were studied in an attempt the cellular basis of these disorders. The phenotype and function of T and B cells were investigated. According to the clinical and laboratory fetures, the patients were classified as one case of severe combined immunodeficiency (SCID), two of ataxia-telangiectasia (AT), one of Wiskott-Aldrich syndrome (WAAS), one of /edi%george syndrome (DSG), and one of cellular immunodeficiency (CID). The laboratory investigations together with the clinical manifestations permitted a diagnosis of primary immunodeficiency diseases

Ataxia-telangiectasia: estudio inmunológico y bioquimico de cuatro pacientes y once miembros se su familia

Se hace un estudio de 4 casos de ataxia-telangiectasia y 11 miembros de su familia por ambas ascendencias desde los puntos de vista inmunológico y bioquímico......(AU)