Education & Certifications
Doctor of Medicine, Stanford University, MED-MD (2016)
Bachelor of Science, Brown University, Biophysics (2008)
Patients with mutations of the recombination-activating genes (RAG) present with diverse clinical phenotypes, including severe combined immune deficiency (SCID), autoimmunity, and inflammation. However, the incidence and extent of immune dysregulation in RAG-dependent immunodeficiency have not been studied in detail. Here, we have demonstrated that patients with hypomorphic RAG mutations, especially those with delayed-onset combined immune deficiency and granulomatous/autoimmune manifestations (CID-G/AI), produce a broad spectrum of autoantibodies. Neutralizing anti-IFN-α or anti-IFN-ω antibodies were present at detectable levels in patients with CID-G/AI who had a history of severe viral infections. As this autoantibody profile is not observed in a wide range of other primary immunodeficiencies, we hypothesized that recurrent or chronic viral infections may precipitate or aggravate immune dysregulation in RAG-deficient hosts. We repeatedly challenged Rag1S723C/S723C mice, which serve as a model of leaky SCID, with agonists of the virus-recognizing receptors TLR3/MDA5, TLR7/-8, and TLR9 and found that this treatment elicits autoantibody production. Altogether, our data demonstrate that immune dysregulation is an integral aspect of RAG-associated immunodeficiency and indicate that environmental triggers may modulate the phenotypic expression of autoimmune manifestations.
View details for DOI 10.1172/JCI80477
View details for Web of Science ID 000364110000017
View details for PubMedID 26457731
Autoimmunity is highly coincident with immunodeficiency. In a small but growing number of primary immunodeficiencies, autoantibodies are diagnostic of a given disease and implicated in disease pathogenesis. In order to improve our understanding of the role of autoantibodies in immunodeficiencies and to discover novel autoantibodies, new proteomic tools are needed. Protein microarrays have the ability to screen for reactivity to hundreds to many thousands of unique autoantigens simultaneously on a single chip using minimal serum input. Here, we review different types of protein microarrays and how they can be useful in framing the study of primary and secondary immunodeficiencies.
View details for DOI 10.3389/fimmu.2015.00138
View details for PubMedID 25904912
Anti-cytokine autoantibodies (ACAAs) are pathogenic in a handful of rare immunodeficiencies. However, the prevalence and significance of other ACAAs across immunodeficiencies have not yet been described.We profiled ACAAs in a diverse cohort of serum samples from patients with immunodeficiency and assessed the sensitivity and specificity of protein microarrays for ACAA identification and discovery.Highly multiplexed protein microarrays were designed and fabricated. Blinded serum samples from a cohort of 58 immunodeficiency patients and healthy control subjects were used to probe microarrays. Unsupervised hierarchical clustering was used to identify clusters of reactivity, and after unblinding, significance analysis of microarrays was used to identify disease-specific autoantibodies. A bead-based assay was used to validate protein microarray results. Blocking activity of serum containing ACAAs was measured in vitro.Protein microarrays were highly sensitive and specific for the detection of ACAAs in patients with autoimmune polyendocrine syndrome type I and pulmonary alveolar proteinosis, detecting ACAA levels consistent with those reported in the published literature. Protein microarray results were validated by using an independent bead-based assay. To confirm the functional significance of these ACAAs, we tested and confirmed the blocking activity of select ACAAs in vitro.Protein microarrays are a powerful tool for ACAA detection and discovery, and they hold promise as a diagnostic for the evaluation and monitoring of clinical immunodeficiency.
View details for DOI 10.1016/j.jaci.2015.07.032
View details for PubMedID 26365387
Effective therapeutic vaccines often require activation of T cell-mediated immunity. Robust T cell activation, including CD8 T cell responses, can be achieved using antibodies or antibody fragments to direct antigens of interest to professional antigen presenting cells. This approach represents an important advance in enhancing vaccine efficacy. Nucleic acid aptamers present a promising alternative to protein-based targeting approaches. We have selected aptamers that specifically bind the murine receptor, DEC205, a C-type lectin expressed predominantly on the surface of CD8α+ dendritic cells (DCs) that has been shown to be efficient at facilitating antigen cross-presentation and subsequent CD8+ T cell activation. Using a minimized aptamer conjugated to the model antigen ovalbumin (OVA), DEC205-targeted antigen cross-presentation was verified in vitro and in vivo by proliferation and cytokine production by primary murine CD8+ T cells expressing a T cell receptor specific for the MHC I-restricted OVA257-264 peptide SIINFEKL. Compared with a nonspecific RNA of similar length, DEC205 aptamer-OVA-mediated antigen delivery stimulated strong proliferation and production of IFN-γ and IL-2. The immune responses elicited by aptamer-OVA conjugates were sufficient to inhibit growth of established OVA-expressing B16 tumor cells. Our results demonstrate a new application of aptamer technology for the development of effective T cell-mediated vaccines.Molecular Therapy (2014); doi:10.1038/mt.2014.51.
View details for DOI 10.1038/mt.2014.51
View details for PubMedID 24682172
To the Editor: In their Shattuck Lecture (Sept. 4 issue),(1) Kandel and Kandel share evidence of a biochemical basis by which the use of nicotine enhances the addictive potential of cocaine. The experiments they report measured addiction-related behaviors and molecular markers of addiction in mice. However, before we conclude that nicotine is a biochemical gateway drug, it is important to compare the effect size of the biochemical properties of nicotine against the enormity and ubiquity of social factors associated with tobacco products. Whether tobacco use is causal of, or only associated with, future drug use remains a central question. Kandel . . .
View details for DOI 10.1056/NEJMc1411785#SA1
View details for PubMedID 25409385
Portal vein thrombosis has been documented after laparoscopic general surgery and has been uncommonly observed after laparoscopic bariatric surgery. Among bariatric operations, the sleeve gastrectomy is being performed with ever-increasing frequency. Here we report the case of a man who presented with portal vein thrombosis after laparoscopic sleeve gastrectomy.A 41-y-old man underwent an uneventful laparoscopic sleeve gastrectomy for the treatment of morbid obesity, and presented on postoperative day 10 with nonfocal abdominal pain, nausea, vomiting, and leukocytosis. Computed tomography revealed portal vein thrombosis, which was found in the setting of Clostridium difficile colitis.Portal vein thrombosis may be identified with increasing frequency as the number of laparoscopic bariatric operations continues to increase. A high index of suspicion is necessary to diagnose this rare, but potentially lethal, complication.
View details for DOI 10.4293/108680812X13517013316636
View details for Web of Science ID 000314201800023
View details for PubMedID 23484577
Autoreactivity to histones is a pervasive feature of several human autoimmune disorders, including systemic lupus erythematosus (SLE). Specific post-translational modifications (PTMs) of histones within neutrophil extracellular traps (NETs) may potentially drive the process by which tolerance to these chromatin-associated proteins is broken. We hypothesized that NETs and their unique histone PTMs might be capable of inducing autoantibodies that target histones.We developed a novel and efficient method for the in vitro production, visualization, and broad profiling of histone-PTMs of human and murine NETs. We also immunized Balb/c mice with murine NETs and profiled their sera on autoantigen and histone peptide microarrays for evidence of autoantibody production to their immunogen.We confirmed specificity toward acetyl-modified histone H2B as well as to other histone PTMs in sera from patients with SLE known to have autoreactivity against histones. We observed enrichment for distinctive histone marks of transcriptionally silent DNA during NETosis triggered by diverse stimuli. However, NETs derived from human and murine sources did not harbor many of the PTMs toward which autoreactivity was observed in patients with SLE or in MRL/lpr mice. Further, while murine NETs were weak autoantigens in vivo, there was only partial overlap in the immunoglobulin G (IgG) and IgM autoantibody profiles induced by vaccination of mice with NETs and those seen in patients with SLE.Isolated in vivo exposure to NETs is insufficient to break tolerance and may involve additional factors that have yet to be identified.
View details for DOI 10.1186/ar3707
View details for Web of Science ID 000304698800039
View details for PubMedID 22300536