Schroeder, Ph.D, John


Schroeder, John

The Johns Hopkins University School of Medicine

Department of Medicine

Division of Allergy & Clinical Immunology

Johns Hopkins Asthma & Allergy Center

5501 Hopkins Bayview Circle, Rm. 2A.2

Baltimore, MD 21224-6801

Tel:  410-550-2127

Email: schray@jhmi.edu     


Biography:

John T. Schroeder, Ph.D. is currently Associate Professor of Medicine at The Johns Hopkins University School of Medicine in Baltimore, Maryland.  He joined the Division of Allergy and Clinical Immunology of the Department of Medicine in 1995 after a research postdoctoral fellowship in the division under the mentorship of Dr. Lawrence M. Lichtenstein.  He is a member of the American Academy of Allergy, Asthma and Immunology.  He has served on NIH Study Sections in Hypersensitivity, Autoimmunity and Immunology, well as Innate Immunity and Inflammation, and various Special Emphasis panels.  He has served on the Editorial Board for Allergy and also is a peer-reviewer for many leading allergy and immunology journals.  He is the author of more than 70 peer-reviewed publications, reviews and book chapters.  He lectures on a variety of topics regarding basophils, mast cells, dendritic cells, and cytokines in allergic inflammation.


Research Interests:

1) Mechanisms regulating cytokine/mediator release by IgE receptor-bearing cells.

This laboratory during the last two decade has focused on understanding the role human basophils and mast cells play in allergic reactions, as it relates not only to their secretion of potent inflammatory mediators (e.g. histamine and leukotriene C4), but also to their production of pro-inflammatory cytokines. Particular emphasis has been on studies investigating the parameters and mechanisms underlying the production of IL-4 and IL-13 by basophils, as these two cytokines are known to play a critical role in the pathogenesis of allergic disease. As a result, this laboratory has played a significant role in characterizing the basophil as a major source of these "Th2-like" cytokines, so named for their initial description in a subclass of T helper lymphocytes. We first demonstrated this response in vitro using basophils isolated from blood and under conditions involving IgE-dependent and IgE-independent activation. More recently, we have extended these observations to clinically relevant disease by showing that basophils infiltrating the airways following allergen challenge are also a primary source of these cytokines. Overall, the implications are that basophils, by secreting all of the major products linked to allergic inflammation (i.e. IL-4, IL-13, histamine and LTC4), orchestrate both immunomodulatory and effecter roles in allergic disease.

We have long utilized human cells rather than cell lines in order to address the parameters, signal transduction, and pharmacological aspects underlying clinically relevant basophil and mast cell responses. As a result, this laboratory has established protocols for rapidly isolating large numbers of basophils at high purity from human blood, and for growing culture-derived mast cells/basophils from human progenitor cells. A variety of assays and techniques are also in place for concurrently detecting cytokines and mediators following a wide range of stimuli. These have facilitated the in vitro testing of numerous anti-allergic drugs for inhibitory activity on basophil and mast cell activation. 


2) Counter-regulation between the IgE and innate immune receptors on human immature dendritic cell subtypes

Our interests in human dendritic cell subtypes, both plasmacytoid dendritic cells (pDC) and myeloid dendritic cells (mDC), stems from the fact that these cells are also capable of binding IgE with high affinity. In fact, our work investigating the function of the FceRIa variant expressed by pDCs led to the novel concept that cross-linking this receptor plays an important role in suppressing the innate immune function of these cells. In contrast, this work has also shown that certain innate immune-associated receptors (e.g. TLR9) play an important role in counter-regulating IgE receptor responses in these cells. This work arose from studies investigating human basophils. In brief, the Type I IFNs (e.g. IFN-alpha) that are produced at very high levels by plasmacytoid dendritic cells, suppress basophil priming, especially that which is heightened in allergic disease. It has also become evident from our work (and that of others) that IFN-a production by pDCs (and likely other innate immune responses) is impaired in allergic disease –perhaps a consequence of allergen binding and cross-linking specific IgE/receptor complexes on the surface of these cells.

 

Mentor List:

 

Advisees (Postdoctoral / visiting scientists) –current position

 

                        Pamela Frischmeyer-Guerrerio, M.D., Ph.D. (July 2007- July

                        2009)

                        Assistant Professor

                        Division of Allergy and Clinical Immunology

                        Department of Pediatrics

                        Johns Hopkins University

 

                        Jody Tversky, MD (Fall 2005 - July 2008)

                        Assistant Professor

                        Division of Allergy and Clinical Immunology

                        Department of Medicine

                        Mount Sinai Medical Center

                       

                        Trong Le, M.D. (summer 2005-2007)

                        Allergy Attending Physician

                        Division of Allergy and Clinical Immunology

                        Department of Pediatrics

                        Children’s Hospital of Philadelphia

 

                        Yi-Hsing Chen, M.D. (Jan. 2003-Sept. 2003)

                        Attending Physician

                        Division of Allergy, Immunology and Rheumatology

                        Taichung Veterans General Hospital

 

                        Hyun-Hee Kim, M.D., Ph.D.  2000-2002 

                        Chief and Professor of Pediatrics, Holy Family Hospital, 

                         Catholic University, College of Medicine, Seoul, Korea

 

                        Aytul Sin, M.D. 1999-2000

                        Assistant Professor of Medicine, Ege University School of 

                         Medicine, Department of Internal Medicine, Division of 

                         Allergy and Clinical Immunology, Izmir, Turkey

 

                        Angela C. Redrup, Ph.D. 1996-1997

                        Instructor: Kings College, London England

 

                      Graduate Student Preliminary Examination Committees for the 

                       Ph.D. degree:

 

                        -Greg M. Delgoffe   (Graduate Studies in Immunology,

                        JHU-SOM)  2007

                        -Dallas Fries    (Graduate Studies in Immunology, 

                         JHU-SOM)    2006

 

 

 

Other: (lab info, pictures)

 

 

 

 

 

 

 

 

 

 

Updated August 2011

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