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Detection of Subclinical Arthritis in Mice by a Thrombin Receptor–Derived Imaging Agent
Author(s) -
Friedman Beth,
Whitney Michael A.,
Savariar Elamprakash N.,
Caneda Christa,
Steinbach Paul,
Xiong Qing,
Hingorani Dina V.,
Crisp Jessica,
Adams Stephen R.,
Kenner Michael,
Lippert Csilla N.,
Nguyen Quyen T.,
Guma Monica,
Tsien Roger Y.,
Corr Maripat
Publication year - 2018
Publication title -
arthritis and rheumatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.106
H-Index - 314
eISSN - 2326-5205
pISSN - 2326-5191
DOI - 10.1002/art.40316
Subject(s) - arthritis , ex vivo , rheumatoid arthritis , chemistry , synovitis , pathology , fibrin , inflammation , in vivo , inflammatory arthritis , medicine , immunology , microbiology and biotechnology , biology , in vitro , biochemistry
Objective Functional imaging of synovitis could improve both early detection of rheumatoid arthritis (RA) and long‐term outcomes. Given the intersection of inflammation with coagulation protease activation, this study was undertaken to examine coagulation protease activities in arthritic mice with a dual‐fluorescence ratiometric activatable cell‐penetrating peptide (RACPP) that has a linker, norleucine (Nle)‐TPRSFL, with a cleavage site for thrombin. Methods K/BxN‐transgenic mice with chronic arthritis and mice with day 1 passive serum‐transfer arthritis were imaged in vivo for Cy5:Cy7 emission ratiometric fluorescence from proteolytic cleavage and activation of RACPP NleTPRSFL . Joint thickness in mice with serum‐transfer arthritis was measured from days 0 to 10. The cleavage‐evoked release of Cy5‐tagged tissue‐adhesive fragments enabled microscopic correlation with immunohistochemistry for inflammatory markers. Thrombin dependence of ratiometric fluorescence was tested by ex vivo application of RACPP NleTPRSFL and argatroban to cryosections obtained from mouse hind paws on day 1 of serum‐transfer arthritis. Results In chronic arthritis, RACPP NleTPRSFL fluorescence ratios of Cy5:Cy7 emission were significantly higher in diseased swollen ankles of K/BxN‐transgenic mice than in normal mouse ankles. A high ratio of RACPP NleTPRSFL fluorescence in mouse ankles and toes on day 1 of serum‐transfer arthritis correlated with subsequent joint swelling. Foci of high ratiometric fluorescence localized to inflammation, as demarcated by immune reactivity for citrullinated histones, macrophages, mast cells, and neutrophils, in soft tissue on day 1 of serum‐transfer arthritis. Ex vivo application of RACPP NleTPRSFL to cryosections obtained from mice on day 1 of serum‐transfer arthritis produced ratiometric fluorescence that was inhibited by argatroban. Conclusion RACPP NleTPRSFL activation detects established experimental arthritis, and the detection of inflammation by RACPP NleTPRSFL on day 1 of serum‐transfer arthritis correlates with disease progression.