Research

Description of our Research

Leukocyte migration from the blood and lymph into tissues and transport of antigens into secondary lymphoid organs are critical for the generation of normal immune responses. Dysregulation of these dynamic processes contribute to the pathogenesis of all inflammatory diseases and several other diseases, such as cancer. We study the molecular mechanisms and functional implications of antigen and leukocyte traffic in the body. We are interested in defining the routes and mechanisms by which antigens enter the lymph node parenchyma via the lymphatic vasculature. We elucidate the role of stromal cells of draining lymph nodes in antigen handling. We also study the effects of tissue niche on the plasticity and functions of macrophages and other myeloid cells.  Moreover, we analyze therapeutic potential of the new leukocyte trafficking molecules we have identified on blood and lymphatic vessels (e.g. vascular adhesion protein-1 (VAP-1), CD73, stabilin-1, plasmalemma vesicle associated protein (Plvap)) in inflammation and cancer.  As a separate line of research, we study the value of leukocyte and endothelial cell subsets and soluble inflammatory mediators (e.g., cytokines) as biomarkers of disease in population and patient cohorts.

Selected Publications

1. Rantakari P, Auvinen K, Jäppinen J, Kapraali M, Valtonen J, Karikoski M, Gerke H, , IIftakhar-E-Khuda I, Keuschnigg J, Umemoto E, Tohya K, Miyasaka M, Elima K, Jalkanen S, Salmi M. Plvap controls the entry of antigens to conduits and lymphocyte transmigration to parenchyma in the lymphatic sinus of lymph nodes. Nat Immunol 16:386-96, 2015.
2. Rantakari P, Jäppinen N, Lokka E, Mokkala E, Gerke H, Peuhu E, Ivaska J, Elima K, Auvinen K, Salmi M.. Fetal liver endothelium regulates the seeding of tissue-resident macrophages. Nature, 538:392-396, 2016.
3. Santalahti K, Havulinna A, Maksimow M, Zeller T, Blankenberg S,Vehtari A, Joensuu H, Jalkanen S, Salomaa V, Salmi M. Plasma levels of HGF and PlGF predict mortality in a general population: a prospective cohort study. J Intern Med, 282(4):340-352, 2017.
4. Jäppinen N, Félix I, Lokka E, Tyystjärvi S, Pynttäri A, Lahtela T, Gerke H, Elima K, Rantakari P, Salmi M. Fetal-derived macrophages dominate in adult mammary glands. Nat Commun. 10:281, 2019.
5. Kähäri L, Fair-Mäkelä R, Auvinen K, Rantakari P, Jalkanen S, Ivaska J, Salmi M. Transcytosis route mediates rapid delivery of intact antibodies to draining lymph nodes. J Clin Invest. 129:3086-3102, 2019.
6. Jalkanen S, Salmi M. Lymphatic endothelial cells of the lymph node. Nat Rev Immunol. 20:566-578,
7. Lokka E, Lintukorpi L, Cisneros-Montalvo S, Mäkelä JA, Tyystjärvi S, Ojasalo V, Gerke H, Toppari J, Rantakari P, Salmi M. Generation, localization and functions of macrophages during the development of testis. Nat Commun. 11,:4375, 2020.
8. Hansen D, Jensen JER, Andersen CAT, Jakobsgaard PR, Havelund J, Lauritsen L, Mandacaru S, Siersbaek M, Shackleton OL, Inoue H, Brewer JR, Schwabe RF, Blagoev B, Faergeman NJ, Salmi M, Ravnskjaer K. Hepatic stellate cells regulate liver fatty acid utilization via plasmalemma vesicle-associated protein. Cell Metabolism 37:971-986, 2025. doi: 10.1016/j.cmet.2025.01.022
9. Fair-Mäkelä R, Thorén P, Näsiaho J, Sundqvist P, Piiroinen I, Kähäri L, Julkunen I, Ivaska J, Hub E, Rot A, Ghimire B, Alanko J, Salmi M.COVID-19 vaccine type controls stromal reprogramming in draining lymph nodes. Sci Immunol. 15;10 (110):eadr6787, 2025.