Lajoie
Lab

Asthma & Allergy Research · Johns Hopkins School of Medicine

Why do only some people get allergies?

And why are they becoming more common? We study how the innate immune system misreads otherwise harmless environmental proteins — and how that misreading sets off the type 2 inflammation behind allergic airway disease.

Directed by

Stephane Lajoie, PhD

Associate Professor, Otolaryngology–Head & Neck Surgery
Johns Hopkins School of Medicine

Secondary appointments — Environmental Health, and Molecular Microbiology & Immunology, Bloomberg School of Public Health

// the burden

Why it matters

Asthma and allergic disease are common in the United States — and, over the long run, rising. The environment our immune systems misread now affects a large share of the population.

Long-run asthma prevalence. The 1980–1996 and 2001–2021 series are measured differently and aren’t directly comparable across the gap.

Diagnosed allergic conditions in 2024 — roughly one in three people report at least one.

// research

What we work on

In susceptible people, allergens are misread as dangerous, tipping the airway toward an immunogenic rather than a regulatory state. We ask how the innate immune system draws that wrong conclusion, and what keeps the resulting inflammation running.

How the airway epithelium sets the tone of the immune response to environmental exposures.
How stromal cells support the allergic neighborhoods that form in tissue.
Innate immune cells — ILC2s and special macrophage subsets — that sustain allergic airway inflammation.
Neuronal output as a rheostat for allergic immunity.

// people

The group

Camilla Melegari, MDResearch & Clinical Fellow

Honorables

BaboLab mascotWe implore Babo for grant money.

IkjunLab spiritual healerPawsitive vibes only.

Naina GourLab ninjaPer ChatGPT: “much like a raccoon — mischievous and resourceful, approaching research with a curious demeanor.”

Alumni

Bella Qiu — ScM (2024–2026); Department of MMI, JHSPH
Kellia Karambizi — ScM (2024–2026); Department of MMI, JHSPH
Maddy Zhao — ScM (2024–2026); Department of MMI, JHSPH
Elizabeth Murray — ScM (2023–2025); Department of MMI, JHSPH
Shruthi Mahaganapathy — ScM (2023–2025); Department of MMI, JHSPH
Sarah Thomas — ScM (2022–2024); Department of MMI, JHSPH
Aishwarya Atakkatan — ScM (2021–2023); Department of MMI, JHSPH
Hsin Tzu Keng — ScM (2021–2023); Department of MMI, JHSPH
Aishwarya Magesh — MS (2021–2022); Biotechnology, JHU

Undergraduate researchers

Lawrence Wang — JHU
Isabella Huang — JHU

// publications

Selected publications

Full list on Google Scholar →

Atakkatan A, Magesh A, Yong H, Murray E, Gour N, Lajoie S. Complement-producing adventitial fibroblasts form an IL-33 alarmin hub that maintains ILC2s during airway allergy. Cell Reports, 2025. [ PubMed ] [ DOI ]
Thomas SA, Lajoie S. Complement's involvement in allergic Th2 immunity: a cross-barrier perspective. Journal of Clinical Investigation, 2025. [ PubMed ] [ DOI ]
Thomas SA, Yong H, Rule AM, Gour N, Lajoie S. Air pollution drives macrophage senescence through a phagolysosome–15-lipoxygenase pathway. ImmunoHorizons, 2024. [ PubMed ] [ DOI ]
Yong HM, Gour N, Sharma D, Khalil SM, Lane AP, Lajoie S. Epigenetic regulation of epithelial dectin-1 through an IL-33–STAT3 axis in allergic disease. Allergy, 2022. [ PubMed ] [ DOI ]
Smole U, Gour N, Phelan J, et al., Lajoie S, Wills-Karp M. Serum amyloid A is a soluble pattern recognition receptor that drives type 2 immunity. Nature Immunology, 2020. [ PubMed ] [ DOI ]