About

Nicholas Kenyon, M.D., M.A.S., is a Professor of Medicine at UC Davis Health and holds multiple leadership roles including Director of the NHLBI T32 Training Program in Comparative Lung Biology and Medicine, Associate Director of the Clinical Translational Science Center, and Director of the UC Davis Asthma Network. His clinical interests focus on severe asthma in adults, chronic obstructive pulmonary disease (COPD), environmental health, and non-invasive markers of airway disease and critical care. Dr. Kenyon's research primarily centers on airways diseases and lung injury, with a particular emphasis on developing new medications to improve the care of patients with severe asthma. His laboratory work has included NIH-funded studies on nitric oxide in airway inflammation, leading to an FDA new drug application and clinical trials involving L-arginine in adult severe asthma. He is also engaged in research on breath biomarkers and diagnostics in collaboration with colleagues in the College of Engineering at UC Davis. As a physician-scientist, he is dedicated to training the next generation of physician-scientists and clinical fellows, serving as the Director of the CTSC Pre-doctoral Training Program and incoming Associate Director of the NIH Training Program. Dr. Kenyon's educational background includes a B.A. in English and Biology from Amherst College, an M.D. from the University of Vermont College of Medicine, and an M.A.S. in Clinical Research from UC Davis. His clinical training includes internal medicine at the University of Wisconsin and fellowship in Pulmonary and Critical Care Medicine at UC Davis Medical Center. His contributions have been recognized through awards such as the Chair’s Recognition Award from UC Davis Health and the Outstanding Teaching Award for Pulmonary and Critical Care Medicine Fellows.

Research topics

• Computer Science
• Medicine
• Pathology
• Artificial Intelligence
• Engineering
• Family medicine
• Business
• Nursing
• Real-time computing
• Human–computer interaction
• Medical education
• Intensive care medicine
• Marketing
• Biology
• Risk analysis (engineering)
• Embedded system
• Psychology
• Veterinary medicine
• Internal medicine
• Physical therapy
• Virology

Selected publications

• Wildfire smoke exposure and persistent respiratory symptoms and illness: a retrospective cohort study

  Respiratory Research · 2026-05-12

  articleOpen access

  Abstract Background Wildfire smoke is a growing public health hazard yet there is limited evidence on its intermediate or long-term respiratory health effects. Studying the association between wildfire smoke exposure and indicators of impaired respiratory health such as persistent respiratory illness and respiratory symptoms can help elucidate the associated risk of developing chronic lung disease. We sought to determine whether wildfire smoke exposure is associated with medically-attended respiratory illness (MARI) and respiratory symptoms persisting beyond the acute wildfire period. Methods This was a population-based retrospective cohort study of adults without chronic lung disease aside from self-reported asthma, who reported living in a Northern California community affected by a wildfire in 2018. The primary predictor was mean daily wildfire-dominated fine particulate matter (PM 2.5 ) exposure during a wildfire, estimated based on home and evacuation locations. The primary outcomes were respiratory illness requiring medical attention (MARI) at least one month after the wildfire and any respiratory symptom (“asthma attack,” bronchitis, cough, respiratory infection, or wheezing) that persisted to the time of the survey (mean 8.5 months after wildfire). Results Among 1,381 adults in the study, the mean daily PM 2.5 exposure during a wildfire was 87.2 μg/m 3 (SD 44.3). After adjustment for demographic covariates, smoking status, asthma, and allergies, one standard deviation higher wildfire-dominated PM2.5 exposure was associated with greater risk of MARI (RR 1.18, 95% CI 1.06 - 1.31, p =0.002) and persistent self-reported asthma attacks (RR 1.28, 95% CI 1.03 - 1.59, p =0.026), but not associated with other persistent respiratory symptoms. Each additional day exposed to PM 2.5 >125 μg/m 3 (EPA threshold for very unhealthy or hazardous air quality) was associated with an 11% increased risk of future severe MARI leading to emergency room visit or hospitalization (RR 1.11, 95% CI 1.02 – 1. 20, p =0.018). Conclusions Exposure to wildfire-dominated PM 2.5 is associated with increased risk of respiratory illness and symptoms which persist for months beyond the acute wildfire period and may indicate risk of future chronic lung disease. Additional days of exposure to very unhealthy or hazardous range PM 2.5 levels are associated with increased risk of ongoing respiratory morbidity and emergency healthcare utilization in the adult general population.

  PublisherDOI

• A silicon microneedle array atmospheric pressure plasma ionization source for real-time trace gas chemical analysis

  Microsystems & Nanoengineering · 2026-05-21

  articleOpen access

  Abstract We have engineered, fabricated, and qualified ZAPPI ( Z onal A tmospheric P ressure P lasma I onizer), an array of hollow electrical discharge emitter micro needles for volatile organic compound ionization and detection. The device is optimized for portable applications requiring low power and trace analyte abundance. The 250 µm interelectrode gap requires just 1.1 mW, detecting analytes at $$\dot{m}=23{ng}{s}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mover> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mo>̇</mml:mo> </mml:mover> <mml:mo>=</mml:mo> <mml:mn>23</mml:mn> <mml:mi>ng</mml:mi> <mml:msup> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> mass flow rates. We further demonstrate ZAPPI’s efficacy by ionizing several compounds representing different point of detection applications. These compounds include DMMP a simulated chemical warfare nerve agent, 2-butanone a widely studied biomarker in exhaled breath, Methyl salicylate a flavoring agent, and Naphthalene a toxic polycyclic aromatic hydrocarbon by-product in combustion. The wafer level fabrication of the ZAPPI device opens future possibilities for highly integrated trace gas detection lab on chip systems.

  PublisherOA PDFDOI

• PrecISE—a biomarker-stratified adaptive trial of 5 interventions in severe asthma: Final protocol and the baseline cohort

  Journal of Allergy and Clinical Immunology · 2026-02-01 · 1 citations

  article
  PublisherDOI

• Impacts of vaping and marijuana use on airway health as determined by exhaled breath condensate (EBC)

  Respiratory Research · 2025-02-21 · 4 citations

  articleOpen access

  Across the United States, there is increased use of cannabis products and electronic delivery systems for cannabis products and nicotine, yet little is known about their impacts on lung health. We analyzed exhaled breath condensate of 254 participants who were non-users and users who used cannabis and tobacco products. The 132 participants reported using a product ("users") were distributed into cohorts of tobacco products and cannabis products, with some participants following into multiple cohorts. Targeted analysis of inflammatory oxylipins found up-regulation among persons using tobacco products, while cannabis users had concentrations closer to nonusers, and often down-regulated. Untargeted screening of 403 significant metabolites found tobacco users had similar breath profiles, and that cannabis users had a similar profile that was closer to the profile of nonusers. Metabolites were significantly higher in breath of people using combustion products (tobacco and cannabis) relative to nonusers, and significantly lower in e-device users (nicotine and THC). Our work demonstrates the relative impact of e-delivery systems and cannabis products compared to traditional cigarette smoking on lung metabolic profiles.

  PublisherOA PDFDOI

• Lactate dehydrogenase-induced DNA Topoisomerase 1 is a novel regulator of smooth muscle cell proliferation and remodeling in pulmonary arterial hypertension

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-11-12

  preprint

  Pulmonary arterial hypertension (PAH) manifests by increased proliferation and survival of pulmonary vascular cells in small pulmonary arteries (PAs), PA remodeling and unresolved increase of PA pressure. PA smooth muscle cells (PASMCs) in PAH undergo metabolic shift to glycolysis resulting in over-production of lactate, hyper-proliferation, and apoptosis resistance, but the mechanisms are not completely understood. By using lung tissues and pulmonary vascular cells from PAH and non-diseased human lungs, unbiased proteomics, network analysis, and gain-and-loss of function approaches, we here report that up-regulation of lactate dehydrogenase A (LDHA)-lactate axis promotes PASMC-specific over-lactylation and consequent over-accumulation of DNA topoisomerase 1 (TOP1) in small remodeled PAs from PAH lungs, leading to the up-regulation of Akt-mechanistic target of rapamycin 1 (mTORC1) signaling, hyper-proliferation, and reduced apoptosis. Smooth muscle-specific LDHA knockdown prevented, and Ldha inhibitor oxamate reversed SU5416/hypoxia-induced TOP1 accumulation, pulmonary vascular remodeling, and pulmonary hypertension (PH) in mice. Pharmacological inhibition of TOP1 with indotecan suppressed Akt-mTORC1, decreased proliferation, induced apoptosis in human PAH, but not control PASMCs, and reversed PA remodeling, PH, and RV dysfunction in rats. Collectively, these data provide a novel mechanistic link from LDHA-driven lactate over-production through lactylation and overaccumulation of TOP1, to the up-regulation of Akt-mTORC1, hyper-proliferation and apoptosis resistance of PASMCs, pulmonary vascular remodeling, and PH, and identify TOP1 as a new potentially attractive molecular target for the remodeling-focused therapeutic intervention. Take-home message: LDHA-lactate-induced over-lactylation and overaccumulation of Topoisomerase 1 (TOP1) promotes pulmonary artery smooth muscle cell hyper-proliferation, remodeling, and pulmonary arterial hypertension, which are reversed by TOP1 inhibitor indotecan.

  PublisherDOI

• Investigating Asthma After Coccidioidomycosis Among Patients With Commercial Health Insurance, United States, 2017–2022

  Mycoses · 2025-02-01 · 2 citations

  articleOpen access

  ABSTRACT Background The relationship between asthma and coccidioidomycosis has not been fully described. We have hypothesised that Coccidioides could trigger inflammatory airway responses, similar to other fungi. Objectives: To estimate the frequency of new‐onset asthma‐related symptoms after coccidioidomycosis and identify potentially associated factors. Patients/Methods We used a large health insurance claims database to identify patients with coccidiomycosis with and without an asthma diagnosis code or a short‐acting β 2 agonist prescription in the year after diagnosis. Results Thirteen per cent of 1657 patients with an asthma diagnosis code or a short‐acting β 2 agonist prescription (median 2.5 months later). Conclusions Increased healthcare provider awareness of asthma as a potential coccidioidomycosis complication could benefit patients, especially female patients and patients with severe pulmonary infection.

  PublisherOA PDFDOI

• A device for volatile organic compound (VOC) analysis from skin using heated dynamic headspace sampling

  Journal of Breath Research · 2025-04-15 · 1 citations

  articleOpen access

  Human skin is an important source of volatile organic compounds (VOCs) offering noninvasive methods to gain clinical metabolite information. This work was focused on the development of a skin sampling device based on a dynamic headspace sampling method with the addition of temperature to increase VOC metabolite recovery. The device preconcentrates skin VOC emissions onto a sorbent substrate, which can either be preserved for offline analysis or attached to a real time sensor downstream. In this work, skin VOC samples were analyzed offline using thermal desorption-gas chromatography-mass spectrometry. A list of 10 common skin VOCs was pre-selected to optimize parameters of sampling time, sampling temperature, and sorbent selection. Overall, this study highlights an effective skin VOC sampling technology with a heating dimension (40 °C, rather than 30 °C or no heating) with a sampling time of 15 min (rather than 5 or 30 mins) and onto Tenax TA sorbent (rather than PDMS), which collectively increases the recovery of compounds with lower vapor pressure and decreases the observed variability in skin VOC measurements. Finally, a list of 79 skin VOC compounds were detected and identified within a cohort of 20 young, healthy volunteers.

  PublisherDOI

• Harnessing breath biomarkers for pneumonia diagnosis and prognosis

  Expert Review of Respiratory Medicine · 2025-11-24

  articleOpen accessSenior author

  INTRODUCTION: Pneumonia is a major cause of death and disability worldwide. A host of pathogens causes pneumonia, and pneumonia presents with a remarkable heterogeneity of clinical symptoms and signs and has varied outcomes. Current approaches to pneumonia diagnosis and risk stratification lack precision such that there is no universally agreed upon biomarker or scoring system. These limitations have prompted calls for novel, noninvasive, and more precise approaches to better diagnosing pneumonia and predicting outcomes. AREAS COVERED: We performed a comprehensive literature search through PubMed to identify studies reporting on breath biomarkers in pneumonia published up to 31 July 2025. This manuscript explores breath-based metabolomics as a novel approach to biomarker development in pneumonia. It describes breath collection methods, including devices available and types of breath samples for analysis. It reviews the potential role of exhaled breath analysis to expedite pneumonia diagnosis, monitor response to therapy, and predict clinical trajectory. EXPERT OPINION: Breath-based metabolomics could improve the recognition and management of pneumonia. It is a noninvasive, potentially continuous method that provides a direct window into the lung for novel insights into the underlying biology of pneumonia.

  PublisherOA PDFDOI

• OpenDMS: An Open-Source Approach to Differential Mobility Spectrometry

  Analytical Chemistry · 2025-06-19 · 3 citations

  articleOpen access

  Differential mobility spectrometry (DMS) is a powerful gas-phase chemical analysis technique that separates ions based on their differential mobility in an asymmetric electric field, offering high sensitivity and rapid analysis crucial for fields such as proteomics, metabolomics, and environmental monitoring. Despite its advantages, the widespread adoption of DMS technology has been hindered by the high cost, proprietary nature, and lack of flexibility of commercial systems. In this study, we introduce OpenDMS, an open-source differential mobility spectrometry system designed to be accessible, customizable, and cost-effective. OpenDMS is constructed using readily available components with fully documented designs and open-source software for data processing and visualization. We demonstrate the system's performance through detailed dispersion plots and sensitivity analyses, achieving a theoretical limit of detection of 38 ppt and a resolving power of 1.57 at 10 ppb and 836 SV for an ethylbenzene monomer. The ability to interchange ionization sources, such as plasma and UV ionization, highlights the system's versatility. Importantly, we demonstrate that doping is compatible with the OpenDMS with the use of acetone shifting the DMMP monomer peak. By providing an open-source platform, OpenDMS aims to provide a solid foundation for access to DMS technology, fostering innovation and collaboration within the scientific community and accelerating advancements in various scientific fields.

  PublisherDOI

• The Effect of Respiratory Therapist Case Managers Integrated into COPD Clinical Care

  Respiratory Care · 2025-01-28 · 2 citations

  article

  Background: Personalized education and treatment selection can improve health behaviors and outcomes in patients with COPD. However, many patients with COPD have incomplete knowledge of their disease, which leads to undertreated symptoms. We hypothesized that an interdisciplinary care approach to COPD with respiratory therapists (RTs) integrated in our dedicated clinic will significantly affect care as measured by COPD Assessment Test (CAT) scores, exacerbation rates, and COPD-related hospitalizations. Methods: This study was a retrospective analysis of patients enrolled in the UC Davis Comprehensive COPD Clinic registry. Between January 2018–January 2020, 241 patients were seen. Patients screened ( n = 101) had been followed 12 months post initial COPD clinic visit. Two subjects were excluded from analysis due to discrepancies in CAT assessments, leaving 99 subjects in total. The clinic RT provided assessment, education, and treatment recommendations. We collected CAT scores, exacerbation rates, and those that required hospitalization in the 12 months prior to and after the initial COPD clinic visit. Analysis for CAT is reported as median and interquartile range (IQR), with differences determined by Wilcoxon test. Summary data are reported as percentages, 95% CI, and chi-square test. Results: The initial median CAT score was 22 (IQR 7–34), and 2-month follow-up CAT median was 19 (IQR 11–24, P &lt; .001). There were 115 exacerbations in the 12-month period prior to the initial clinic visit and 63 exacerbations in the 12 months post clinic visit ( P = .006). In the 12-month period prior to the clinic visit, there were 44 hospital admissions for COPD exacerbations compared to 20 hospital admissions for COPD exacerbations in the 12 months after initial clinic visit ( P = .06). Conclusions: Our retrospective study demonstrated significant improvements in symptoms and exacerbation rates and a non-significant reduction in hospitalizations for COPD. This suggests that an RT-facilitated program may improve meaningful clinical outcomes.

  PublisherDOI

Frequent coauthors

• Cristina E. Davis

  University of California, Davis

  112 shared

• Mitchell M. McCartney

  VA Northern California Health Care System

  61 shared

• Amir A. Zeki

  University of California, Davis

  55 shared

• Michael Schivo

  University of California, Davis

  52 shared

• A. Linderholm

  51 shared

• Samuel Louie

  37 shared

• Lisa Franzi

  University of California, Davis

  37 shared

• Richart Harper

  University of California, Davis

  35 shared

Labs

• UC Davis Asthma NetworkPI

Education

• MAS/Clinical Research, Internal Medicine

  University of California, Davis

  2007

• Fellow, Pulmonary & Critical Care Medicine, Internal Medicine

  University of California, Davis

  2001

• Resident, Internal Medicine

  University of Wisconsin Health

  1997

• MD, Medicine

  University of Vermont

  1994

• Bachelor of Arts (BA), English, Biology

  Amherst College

  1988

Awards & honors

• Chair’s Recognition Award, UC Davis Health, Department of In…
• Outstanding Teaching Award, Pulmonary and Critical Care Medi…
• Association of American Medical Colleges Award for Innovativ…
• Joan Oettinger Memorial Research Award, 2012
• Paper of the Year Award - Society of Toxicology, Inhalation…