Neurofilament Light Chain Is a Biomarker of Neurodegeneration in Ataxia Telangiectasia.

Ataxia telangiectasia (A-T) is a progressive and life-limiting disease associated with cerebellar ataxia due to progressive cerebellar degeneration. In addition to ataxia, which is described in detail, the presence of chorea, dystonia, oculomotor apraxia, athetosis, parkinsonism, and myoclonia are typical manifestations of the disease. The study aimed to evaluate the specificity and sensitivity of neurofilament light chain (NfL) as a biomarker of neurodegeneration in relation to SARA score. In this prospective trial, one visit of 42 A-T patients aged 1.3-25.6 years (mean 11.6 ± 7.3 years) was performed, in which NfL was determined from serum by ELISA. Additionally, a neurological examination of the patients was performed. Blood was collected from 19 healthy volunteers ≥ 12 years of age. We found significantly increased levels of NfL in patients with A-T compared to healthy controls (21.5 ± 3.6 pg/mL vs. 9.3 ± 0.49 pg/mL, p ≤ 0.01). There was a significant correlation of NfL with age, AFP, and SARA. NfL is a new potential progression biomarker in blood for neurodegeneration in A-T which increases with age.

Altered Cerebrospinal Fluid (CSF) in Children with Ataxia Telangiectasia.

Ataxia telangiectasia (A-T) is a devastating multi-system disorder characterized by progressive cerebellar ataxia and immunodeficiency. The neurological decline may be caused by multiple factors of which ongoing inflammation and oxidative stress may play a dominant role. The objective of the present investigation was to determine cerebrospinal fluid (CSF) proteins and possible low-grade inflammation and its relation to age and neurological deterioration. In the present study, we investigated 15 patients with A-T from 2 to 16 years. Our investigation included blood and CSF tests, clinical neurological examination, A-T score, and MRI findings. The albumin ratio (AR) was analyzed to determine the blood-brain-barrier function. In addition, inflammatory cytokines (IL-1α, IL-6, IL-8, IL-12 p40, IL-17A, IFN-γ, TNF-α) were measured by the multiplex cytometric bead array. We compared the results with those from an age-matched control group. Three of the A-T patients were analyzed separately (one after resection of a cerebral meningioma, one after radiation and chemotherapy due to leukemia, one after stem cell transplantation). Patient had significantly more moderate and severe side effects due to CSF puncture (vomiting, headache, need for anti-emetic drugs) compared with healthy controls. Total protein, albumin, and the AR increased with age indicating a disturbed blood barrier function in older children. There were no differences for cytokines in serum and CSF with the exception of IL-2, which was significantly higher in controls in serum. The AR is significantly altered in A-T patients, but low-grade inflammation is not detectable in serum and CSF.

Bone marrow transplantation improves the outcome of Atm-deficient mice through the migration of ATM-competent cells.

Ataxia telangiectasia (A-T) is a highly pleiotropic disorder. Patients suffer from progressive neurodegeneration, severe bronchial complications, immunodeficiency, hypersensitivity to radiotherapy and elevated risk of malignancies. Leukemia and lymphoma, along with lung failure, are the main causes of morbidity and mortality in A-T patients. At present, no effective therapy for A-T exists. One promising therapeutic approach is bone marrow transplantation (BMT) that is already used as a curative therapy for other genomic instability syndromes. We used an established clinically relevant non-myeloablative host-conditioning regimen and transplanted green fluorescent protein (GFP)-expressing ataxia telangiectasia mutated (ATM)-competent bone marrow-derived cells (BMDCs) into Atm-deficient mice. GFP expression allowed tracking of the potential migration of the cells into the tissues of recipient animals. Donor BMDCs migrated into the bone marrow, blood, thymus, spleen and lung tissue of Atm-deficient mice showing an ATM-competent phenotype. BMT inhibited thymic lymphomas, normalized T-lymphocyte populations, improved weight gain and rearing activity of Atm-deficient mice. In contrast, no GFP(+) cells were found in the cerebellum or cerebrum, and we detected decreased size index in MRI imaging of the cerebellum in 8-month-old transplanted Atm-deficient mice in comparison to wild-type mice. The repopulation with ATM-competent BMDCs is associated with a prolonged lifespan and significantly improved the phenotype of Atm-deficient mice.

Liver Assessment in Patients with Ataxia-Telangiectasia: Transient Elastography Detects Early Stages of Steatosis and Fibrosis.

Background: Ataxia-telangiectasia (A-T) is a rare autosomal-recessive multisystem disorder characterized by pronounced cerebellar ataxia, telangiectasia, cancer predisposition, and altered body composition. Liver diseases with steatosis, fibrosis, and hepatocellular carcinoma are frequent findings in older patients but sensitive noninvasive diagnostic tools are lacking. Objectives: To determine the sensitivity of transient elastography (TE) as a screening tool for early hepatic tissue changes and serum biomarkers for liver disease. Methods: Thirty-one A-T patients aged 2 to 25 years were examined prospectively from 2016-2018 by TE. In addition, we evaluated the diagnostic performance of liver biomarkers for steatosis and necroinflammatory activity (SteatoTest and ActiTest, Biopredictive, Paris) compared to TE. For calculation and comparison, patients were divided into two groups (<12, >12 years of age). Results: TE revealed steatosis in 2/21 (10%) younger patients compared to 9/10 (90%) older patients. Fibrosis was present in 3/10 (30%) older patients as assessed by TE. We found a significant correlation of steatosis with SteatoTest, alpha-fetoprotein (AFP), HbA1c, and triglycerides. Liver stiffness correlated significantly with SteatoTest, ActiTest, HbA1c, and triglycerides. Conclusion: Liver disease is a common finding in older A-T patients. TE is an objective measure to detect early stages of steatosis and fibrosis. SteatoTest and ActiTest are a good diagnostic assessment for steatosis and necroinflammatory activity in patients with A-T and confirmed the TE results.

Low-dose irradiation prior to bone marrow transplantation results in ATM activation and increased lethality in Atm-deficient mice.

Ataxia telangiectasia is a genetic instability syndrome characterized by neurodegeneration, immunodeficiency, severe bronchial complications, hypersensitivity to radiotherapy and an elevated risk of malignancies. Repopulation with ATM-competent bone marrow-derived cells (BMDCs) significantly prolonged the lifespan and improved the phenotype of Atm-deficient mice. The aim of the present study was to promote BMDC engraftment after bone marrow transplantation using low-dose irradiation (IR) as a co-conditioning strategy. Atm-deficient mice were transplanted with green fluorescent protein-expressing, ATM-positive BMDCs using a clinically relevant non-myeloablative host-conditioning regimen together with TBI (0.2-2.0 Gy). IR significantly improved the engraftment of BMDCs into the bone marrow, blood, spleen and lung in a dose-dependent manner, but not into the cerebellum. However, with increasing doses, IR lethality increased even after low-dose IR. Analysis of the bronchoalveolar lavage fluid and lung histochemistry revealed a significant enhancement in the number of inflammatory cells and oxidative damage. A delay in the resolution of γ-H2AX-expression points to an insufficient double-strand break repair capacity following IR with 0.5 Gy in Atm-deficient splenocytes. Our results demonstrate that even low-dose IR results in ATM activation. In the absence of ATM, low-dose IR leads to increased inflammation, oxidative stress and lethality in the Atm-deficient mouse model.