Aditya Ambati

Dr. Aditya Ambati

Center for Sleep Sciences and Medicine, Stanford University School of Medicine, Palo Alto, CA, USA
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Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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12 April 2019 in Science
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FGFrancine E. Garrett-Bakelman
Francine E. Garrett-Bakelman
MDManjula Darshi
Manjula Darshi
SGStefan J. Green
Stefan J. Green
RGRuben C. Gur
Ruben C. Gur
LLLing Lin
Ling Lin
FTFred Turek
Fred Turek
What to expect after a year in space: Space is the final frontier for understanding how extreme environments affect human physiology. Following twin astronauts, one of which spent a year-long mission on the International Space Station, Garrett-Bakelman et al. examined molecular and physiological traits that may be affected by time in space (see the Perspective by Löbrich and Jeggo). Sequencing the components of whole blood revealed that the length of telomeres, which is important to maintain in dividing cells and may be related to human aging, changed substantially during space flight and again upon return to Earth. Coupled with changes in DNA methylation in immune cells and cardiovascular and cognitive effects, this study provides a basis to assess the hazards of long-term space habitation. Science , this issue p. eaau8650 ; see also p. 127

6 December 2018 in Nature Communications
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JSJens B. Stephansen
Jens B. Stephansen
AOAlexander N. Olesen
Alexander N. Olesen
MOMads Olsen
Mads Olsen
Aditya AmbatiAditya Ambati
Aditya Ambati
Eileen B LearyEileen B Leary
Eileen B Leary
EMEmmanuel Mignot
Emmanuel Mignot
Analysis of sleep for the diagnosis of sleep disorders such as Type-1 Narcolepsy (T1N) currently requires visual inspection of polysomnography records by trained scoring technicians. Here, we used neural networks in approximately 3,000 normal and abnormal sleep recordings to automate sleep stage scoring, producing a hypnodensity graph—a probability distribution conveying more information than classical hypnograms. Accuracy of sleep stage scoring was validated in 70 subjects assessed by six scorers. The best model performed better than any individual scorer (87% versus consensus). It also reliably scores sleep down to 5 s instead of 30 s scoring epochs. A T1N marker based on unusual sleep stage overlaps achieved a specificity of 96% and a sensitivity of 91%, validated in independent datasets. Addition of HLA-DQB1*06:02 typing increased specificity to 99%. Our method can reduce time spent in sleep clinics and automates T1N diagnosis. It also opens the possibility of diagnosing T1N using home sleep studies.

12 December 2018 in Proceedings of the National Academy of Sciences
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GLGuo Luo
Guo Luo
Aditya AmbatiAditya Ambati
Aditya Ambati
LLLing Lin
Ling Lin
MBMélodie Bonvalet
Mélodie Bonvalet
MPMarkku Partinen
Markku Partinen
EMEmmanuel Mignot
Emmanuel Mignot
Significance: This work shows that the amidated terminal ends of the secreted hypocretin (HCRT) peptides (HCRT NH2 ) are autoantigens in type 1 narcolepsy, an autoimmune disorder targeting HCRT neurons. The autoimmune process is usually initiated by influenza A flu infections, and a particular piece of the hemagglutinin (HA) flu protein of the pandemic 2009 H1N1 strain was identified as a likely trigger. This HA epitope has homology with HCRT NH2 and T cells cross-reactive to both epitopes are involved in the autoimmune process by molecular mimicry. Genes associated with narcolepsy mark the particular HLA heterodimer (DQ0602) involved in presentation of these antigens and modulate expression of the specific T cell receptor segments (TRAJ24 and TRBV4-2) involved in T cell receptor recognition of these antigens, suggesting causality.

8 February 2022 in Neurology
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AGAlice Gravier-Dumonceau
Alice Gravier-Dumonceau
RARoxana Ameli
Roxana Ameli
VRVeronique Rogemond
Veronique Rogemond
ARAnne Ruiz
Anne Ruiz
BJBastien Joubert
Bastien Joubert
RMRomain Marignier
Romain Marignier
Background and Objectives To report the clinical, biological, and imaging features and clinical course of a French cohort of patients with glial fibrillary acidic protein (GFAP) autoantibodies. Methods We retrospectively included all patients who tested positive for GFAP antibodies in the CSF by immunohistochemistry and confirmed by cell-based assay using cells expressing human GFAPα since 2017 from 2 French referral centers. Results We identified 46 patients with GFAP antibodies. Median age at onset was 43 years, and 65% were men. Infectious prodromal symptoms were found in 82%. Other autoimmune diseases were found in 22% of patients, and coexisting neural autoantibodies in 11%. Tumors were present in 24%, and T-cell dysfunction in 23%. The most frequent presentation was subacute meningoencephalitis (85%), with cerebellar dysfunction in 57% of cases. Other clinical presentations included myelitis (30%) and visual (35%) and peripheral nervous system involvement (24%). MRI showed perivascular radial enhancement in 32%, periventricular T2 hyperintensity in 41%, brainstem involvement in 31%, leptomeningeal enhancement in 26%, and reversible splenial lesions in 4 cases. A total of 33 of 40 patients had a monophasic course, associated with a good outcome at last follow-up (Rankin Score ≤2: 89%), despite a severe clinical presentation. Adult and pediatric features are similar. Thirty-two patients were treated with immunotherapy. A total of 11/22 patients showed negative conversion of GFAP antibodies. Discussion GFAP autoimmunity is mainly associated with acute/subacute meningoencephalomyelitis with prodromal symptoms, for which tumors and T-cell dysfunction are frequent triggers. The majority of patients followed a monophasic course with a good outcome.

1 May 2021 in Neurology Neuroimmunology & Neuroinflammation
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SMSergio Muñiz-Castrillo
Sergio Muñiz-Castrillo
JHJulie Haesebaert
Julie Haesebaert
LTLaure Thomas
Laure Thomas
AVAlberto Vogrig
Alberto Vogrig
APAnne-Laurie Pinto
Anne-Laurie Pinto
JHJerome Honnorat
Jerome Honnorat
Objective Antibodies against leucine-rich glioma-inactivated 1 (LGI1-Abs) characterize a limbic encephalitis (LE) strongly associated with HLA-DRB1*07:01, although some patients lack LGI1-Abs in CSF or do not carry this allele. Whether they represent a different subtype of disease or have different prognoses is unclear. Methods Retrospective analysis of clinical features, IgG isotypes, and outcome according to LGI1-Ab CSF positivity and DRB1*07:01 in a cohort of anti-LGI1 LE patients. Results Patients with LGI1-Abs detected in both CSF and serum (105/134, 78%) were compared with those who were CSF negative (29/134, 22%). Both groups had similar clinical features and serum levels, but CSF-positive patients had shorter diagnostic delay, more frequently hyponatremia, inflammatory CSF, and abnormal MRI (p < 0.05). Human leukocyte antigen (HLA) genotyping was performed in 72/134 (54%) patients and 63/72 (88%) carried DRB1*07:01. Noncarriers (9/72, 12%) were younger, more commonly women, and had less frequently psychiatric and frontal symptoms (p < 0.05). No difference in IgG isotypes according to CSF positivity or HLA was found (p > 0.05). HLA and IgG isotypes were not associated with poor outcome (mRS >2 at last follow-up) in univariate analyses; CSF positivity was only identified as a poor outcome predictor in the multivariate analysis including the complete follow-up, whereas age and female sex also remained when just the first year was considered. Conclusions LE without CSF LGI1-Abs is clinically indistinguishable and likely reflects just a lesser LGI1-Ab production. HLA association is sex and age biased and presents clinical particularities, suggesting subtle differences in the immune response. Long-term outcome depends mostly on demographic characteristics and the intensity of the intrathecal synthesis.

1 February 2016 in Journal of Immunotherapy
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Journal Article
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QMQingda Meng
Qingda Meng
ZLZhenjiang Liu
Zhenjiang Liu
ERElena Rangelova
Elena Rangelova
TPThomas Poiret
Thomas Poiret
Aditya AmbatiAditya Ambati
Aditya Ambati
MMMarkus Maeurer
Markus Maeurer
Generation of T lymphocytes with reactivity against cancer is a prerequisite for effective adoptive cellular therapies. We established a protocol for tumor-infiltrating lymphocytes (TILs) from patients with pancreatic ductal adenocarcinoma. Tumor samples from 17 pancreatic cancer specimens were cultured with cytokines (IL-2, IL-15, and IL-21) to expand TILs. After 10 days of culture, TILs were stimulated with an anti-CD3 antibody (OKT3) and irradiated allogeneic peripheral blood mononuclear cells. Reactivity of TILs against tumor-associated antigens (mesothelin, survivin, or NY-ESO-1) was detected by intracellular cytokine production by flow cytometry. Cytotoxicity was measured using a Chromium 51 release assay, and reactivity of TILs against autologous tumor cells was detected by INF-γ production (ELISA). TIL composition was tested by CD45RA, CCR7, 4-1BB, LAG-3, PD-1, TIM3, and CTLA-4 marker analysis. TCR Vβ was determined by flow cytometry and TCR clonality was gauged measuring the CDR3 region length by PCR analysis and subsequent sequencing. We could reliably obtain TILs from 17/17 patients with a majority of CD8+ T cells. CD3+CD8+, CD3+CD4+, and CD3+CD4−CD8− [double-negative (DN) T cells] resided predominantly in central (CD45RA−CCR7+) and effector (CD45RA−CCR7−) memory subsets. CD8+ TILs tested uniformly positive for LAG-3 (about 100%), whereas CD4+ TILs showed only up to 12% LAG-3+ staining and PD-1 showed a broad expression pattern in TILs from different patients. TILs from individual patients recognized strongly (up to 11.9% and 8.2% in CD8+) NY-ESO-1, determined by ICS, or mesothelin, determined respectively by TNF-α and IFN-γ production. Twelve of 17 of CD8+ TILs showed preferential expansion of certain TCR Vβ families (eg, 99.2% Vβ13.2 in CD8+ TILs, 77% in the Vβ1, 65.9% in the Vβ22, and 63.3% in the Vβ14 family). TCR CDR3 analysis exhibited monoclonal or oligoclonal TCRs, some of them (eg, CD8+ Vβ13.2) reacting strongly against autologous tumor defined by INF-γ production or by cytotoxicity. We have optimized methods for generating pancreatic cancer–specific TILs that can be used for adoptive cellular therapy of patients with pancreatic cancer.