Department of Comparative Medicine

Charles Frevert, D.V.M, Sc.D.

Professor, Department of Comparative Medicine
Professor, Department of Medicine, Division of Pulmonary Critical Care and Sleep Medicine
Adjunct Professor, Department of Pathology


Doctor of Veterinary Medicine (DVM) Iowa State University
Doctor of Science (Sc.D.) and Fellowship: Harvard School of Public Health

P: 206-221-0364
University of Washington at South Lake Union
315N, Box 358052
850 Republican.
Seattle, WA 98109

Research, Service and Training Interests

Pulmonary Host Defenses: Lung infections place a major burden on public health worldwide and are the leading cause of death from infection in the United States. The importance of lung infections on human and animal health led to my interest in the innate immune system. Early in my research career I focused on the cellular and molecular mechanisms that were responsible for the innate immune response to gram-negative bacteria. Much of my early work was directed towards studying the mechanisms responsible for the pulmonary recruitment of neutrophils into the airspaces of lungs in response to CXC-chemokines and bacteria, which included research in vitro and in vivo (PMIDs: 7995953 and 16804588). Studies were also undertaken to determine if blockade of the pattern recognition receptor, CD14, would provide an effective therapy against the deleterious effects of sepsis. These studies provided evidence of the dichotomous role that the innate immune system plays in the response to microbial pathogens. As hypothesized, the blockade of CD14 prevented the deleterious systemic responses that occur in sepsis. However, this treatment increased bacterial proliferation at the primary site of infection, which limited the use of this therapeutic strategy (PMID: 10799910). In collaboration with investigators at Pacific Northwest National Laboratories we were able to show that proteomics and metabolomics could be used for improved detection and classification of lung infections caused by gram-negative bacteria (PMID: 19209722).

More recently my research has focused on the role of proteoglycans in the innate immune response to lung infection (Fig. 1). Our work with the CXC-Chemokines, murine CXCL1 and CXCL2 and human CXCL8, show that the kinetics of chemokine-glycosaminoglycan interactions control neutrophil migration into the airspaces of the lungs (PMID: 20124102). Work with syndecan-4 shows that this heparan sulfate proteoglycan provides fine control of the innate immune response to gram-negative bacteria in mice by limiting tissue inflammation and injury (PMID: 22427536). Our published work with versican shows that versican is significantly increased during embryonic development, is essentially absent in healthy lungs and is reactivated and is a critical component of the innate immune response to bacterial lung infection (PMID: 26385570).  Deficiency in versican is embryonically lethal, therefore, much of what is known comes from the descriptive and in vitro studies. To address this limitation, my laboratory, in collaboration with Dr. Thomas Wight at Benaroya Research Institute in Seattle, successfully constructed a genetically engineered mouse that results in versican deficiency in cells following Cre recombinase-mediated deletion of Vcan exon 4. When treated with polyinosinic:polycytidylic acid (poly(I:C)), mice with a deficiency of versican in macrophages (LysM/Vcan-/- mice) have increased recovery of leukocytes in bronchoalveolar (BAL) fluid, suggesting that macrophage-derived versican under the conditions studied is anti-inflammatory and is regulated through Trif/Type I interferon signaling (Fig. 2, PMID: 28912382).

Quantitative Digital Pathology: I am currently the Director of the Histology and Imaging Core (HIC) where we make use of advances in the research pathology laboratory, including digital imaging, whole slide scanning, immunohistochemistry (IHC) and automation of stereology and/or image analysis software to obtain objective quantitative data that is testable with statistics. This has allowed us to efficiently obtain unbiased data from tissue sections using image analysis (PMID: 26385570) and stereology (PMID: 24220317). To increase the reproducibility of data generated with quantitative digital pathology we have published a number of manuscripts on the validation and optimization of IHC protocols and the appropriate use of controls (PMID: 25023613 and PMID: 29688318). In addition, to help train the next generation of scientists using IHC and quantitative digital pathology in their research, I serve as the director of two 5 day courses, a special topics course, “Immunohistochemistry and Microscopy”, held annually at the Marine Biological Laboratories in Woods Hole, MA from 2010 to 2017. The IHCM workshop will now be held on June 14th to 19th, 2020 at Montgomery University in Germantown, MD. Additionally, I have been director of the 5-day workshop on “Quantitative Digital Pathology”, held in 2009, 2014 and 2017 at the University of Washington. We are beginning to plan another Quantitative Digital Pathology workshop for the fall of 2021 to be held at the University of School of Medicine at South Lake Union.

Complete Bibliography

Selected Publications


2016 –               Associate Editor, Journal of Histochemistry and Cytochemistry

2015 – 2020      Board of Directors, FASEB

2020 – 2023      Council, Histochemical Society

2018 – 2020      Co-Chair, Proteoglycans GRC, Gordon Research Conference

2019 – 2020      Treasurer Elect, FASEB

2019 – 2022      Executive Committee, FASEB

2020 – 2022      Treasurer, FASEB



1R01AI136468-01 (PIs, Frevert and Altemeier)
Agency: NIH                                     12/12/2017 – 11/31/2022
Title: Impact of versican deficiency on the innate immune response to influenza virus
Major Goal: This proposal addresses the context-dependent manner by which versican, a component of the extracellular matrix, modulates the innate immune response to influenza virus.
Role: Contact PI

1R01AI130280 (PIs, Frevert, Hallstrand and Wight)
Agency: NIH/NIAID                        02/02/2019 – 03/31/2024
Title: Regulation of Allergen Induced Airway Pathophysiology by Versican
Major Goal: To determine the role of versican in providing fine tune control of the immune response to allergens that cause asthma.
Role: Contact PI

59-2090-5-004 (Frevert)
Agency: USDA                                08/01/15-07/31/20
Title: Emerging Diseases, Q-fever: Genetics of Host Response and Transmission Risk for Coxiella burnetii
Major Goal: The objectives of this work are to (1) detail how C. burnetii modulates host cell responses and use this information to (2) identify genetic markers that predict host resistance and (3) develop a vaccine to reduce/prevent transmission.
Role: PI

Figure 1. Activation of the innate immune system in an infected alveolus. The recognition of bacteria and viruses in the lungs results in the activation of Toll-like receptor (TLR) signalling pathways, which leads to pulmonary inflammation and under ideal conditions the clearance of the pathogen. (1) The release of soluble cytokines and chemokines in response to activation of toll-like receptors (TRLs) results in the pulmonary recruitment of neutrophils and other immune cells into the lungs (PMID: 7995953). Activation of TLR4 by lipopolysaccharide results in a rapid and selective increase in the heparan sulfate (HS) proteoglycan, syndecan-4, and the chondroitin sulfate (CS) proteoglycan, versican (PMIDs: 22427536 and 24472738) (2) Cytokines, chemokines, and growth factors bind to HS and CS, which can either increase or decrease their biological activity (PMID: 20124102). (3) Adhesion molecules including the selectins, integrins, and CD44 bind to proteoglycans and glycosaminoglycan, which suggests that these proteins play a critical role in leukocyte adhesion and migration (PMID: 27895126). (4) Chemokine-glycosaminoglycan interactions provide fine-tune control of chemokine-gradient formation and leukocyte migration in tissue. (5) Activation of stromal and immune cells results in the release of MMP. Growing evidence shows that interactions between proteoglycans and MMPs play important roles in the regulation of the innate immune response. (6) Degradation of proteoglycans by MMPs and other proteases controls the amount and localization of proteoglycans in lungs. In addition, proteolytic cleavage of proteoglycans leads to the unmasking of cryptic fragments (PMID: 29290139). Much of this work is reviewed in our manuscript entitled, “Proteoglycans as Immunomodulators of the Innate Immune Response to Lung Infection.” (PMID: 29328866). Published in Gill, S. et al. Anat. Rec. 2010;293(6): 968-81. PMID: 20503391

Figure 2: Schematic depicting pathways by which LPS and poly(I:C) regulate expression of versican, HAS1, and syndecan-4. Engagement of macrophage Toll-like receptors TLR4 and TLR3 by LPS and poly(I:C), respectively, result in enhanced versican expression. Subsequent to activation of TLR4 and TLR3, engagement of the TRIF adaptor molecule is known to activate transcription factors IRF3/7 that lead to production of type I interferons (IFN-α/-β) and recognition by type I interferon receptors (IFNAR1/2). Signaling events downstream of IFNAR activation lead to production of versican; the transcription factor(s) mediating expression of versican in this response is still to be determined. In contrast, expression of both HAS1 and syndecan-4 result from TLR4- and TLR2-mediated engagement of the MyD88 adaptor molecule. In addition, syndecan-4 expression results from TLR4- and TLR3-mediated engagement of TRIF and downstream signaling events that are independent of type I IFNs. Published in Chang MY, et al. Am J Physiol Lung Cell Mol Physiol. 2017: PMID: 28912382.