Biology subjects

Le Fur, M.

Publications and source records attributed to Le Fur, M..

3 recordsLinked to original sources

bioRxiv2026

Rapid imaging of lysyl oxidase activity and fibrogenesis with a turn-on fluorophore

Fibrogenesis is essential to wound healing, but aberrant fibrogenesis is a driver of many chronic diseases and cancers. Lysyl oxidases (LOX) play a pivotal role in fibrogenesis by catalyzing the oxidation of lysine residues to reactive aldehydes (allysine) in collagens and elastin, resulting in the crosslinking and excessive deposition of these extracellular matrix components. Currently, rapid and robust histological assays to visualize the spatial distribution of LOX activity are lacking, hindering the precise validation of anti-fibrotic therapies. Here, we present a histological fluorescent staining method to visualize fibrogenesis (active fibrosis) and LOX activity in tissue sections utilizing a bioorthogonal tag and a click reaction with a turn-on fluorophore. Notably, requiring only two commercial reagents, this protocol can be completed in under two hours and is compatible with other imaging modalities, including second-harmonic generation and immunofluorescence staining. We validated this method across various healthy and fibrotic mouse and human tissue specimens.

bioengineering↗

bioRxiv2024

Localized in vivo prodrug activation using radionuclides

Radionuclides used for imaging and therapy can show high molecular specificity in the body with appropriate targeting ligands. We hypothesized that local energy delivered by molecularly targeted radionuclides could chemically activate prodrugs at disease sites while avoiding activation in off-target sites of toxicity. As proof-of-principle, we tested whether this strategy of "RAdionuclide induced Drug Engagement for Release" (RAiDER) could locally deliver combined radiation and chemotherapy to maximize tumor cytotoxicity while minimizing exposure to activated chemotherapy in off-target sites. MethodsWe screened the ability of radionuclides to chemically activate a model radiation-activated prodrug consisting of the microtubule destabilizing monomethyl auristatin E caged by a radiation-responsive phenyl azide ("caged-MMAE") and interpreted experimental results using the radiobiology computational simulation suite TOPAS-nBio. RAiDER was evaluated in syngeneic mouse models of cancer using fibroblast activation protein inhibitor (FAPI) agents 99mTc-FAPI-34 and 177Lu-FAPI-04, the prostate-specific membrane antigen (PSMA) agent 177Lu-PSMA-617, combined with caged-MMAE or caged-exatecan. Biodistribution in mice, combined with clinical dosimetry, estimated the relationship between radiopharmaceutical uptake in patients and anticipated concentrations of activated prodrug using RAiDER. ResultsRAiDER efficiency varied by 250-fold across radionuclides (99mTc>177Lu>64Cu>68Ga>223Ra>18F), yielding up to 1.22{micro}M prodrug activation per Gy of exposure from 99mTc. Computational simulations implicated low-energy electron-mediated free radical formation as driving prodrug activation. Clinically relevant radionuclide concentrations chemically activated caged-MMAE restored its ability to destabilize microtubules and increased its cytotoxicity by up to 600-fold compared to non-irradiated prodrug. Mice treated with 99mTc-FAPI-34 and caged-MMAE accumulated up to 3000x greater concentrations of activated MMAE in tumors compared to other tissues. RAiDER with 99mTc-FAPI-34 or 177Lu-FAPI-04 delayed tumor growth, while monotherapies did not (P<0.03). Clinically-guided dosimetry suggests sufficient radiation doses can be delivered to activate therapeutically meaningful levels of prodrug. ConclusionThis proof-of-concept study shows that RAiDER is compatible with multiple radionuclides commonly used in nuclear medicine and has the potential to improve the efficacy of radiopharmaceutical therapies to treat cancer safely. RAiDER thus shows promise as an effective strategy to treat disseminated malignancies and broadens the capability of radiopharmaceuticals to trigger diverse biological and therapeutic responses. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/606075v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@18aef37org.highwire.dtl.DTLVardef@5f36eforg.highwire.dtl.DTLVardef@10fa0ccorg.highwire.dtl.DTLVardef@105c416_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Simultaneous PET and molecular MR imaging of cardiopulmonary fibrosis in a mouse model of left ventricular dysfunction

BackgroundAging-associated left ventricular (LV) dysfunction promotes cardiopulmonary fibrogenic remodeling, Group 2 pulmonary hypertension (PH), and right ventricular failure. At the time of diagnosis, cardiac function has declined, and cardiopulmonary fibrosis has often developed. Here, we sought to develop a molecular positron emission tomography (PET)-magnetic resonance imaging (MRI) protocol to detect both cardiopulmonary fibrosis and fibrotic disease activity in an LV dysfunction model. MethodsLV dysfunction was induced by transverse aortic constriction (TAC) in 6-month-old senescence-accelerated prone (SAMP8) mice, a subset of mice received sham surgery. Three weeks post-surgery, mice underwent simultaneous PET-MR imaging at 4.7 T. Collagen-targeted PET and fibrogenesis MR probes were intravenously administered. PET signal was computed as myocardium- or lung-to-muscle ratio (MMR, LMR). Percent signal increase (%SI) and {Delta}LMR were computed from the pre-/post-injection MR images. Tissue specimens were analyzed for hydroxyproline (Hyp) and allysine content. Ventricular structure and function were measured by echocardiography and hemodynamic pressure-volume (PV) loop analysis. ResultsAllysine in the heart (22{+/-}5 (TAC), 13{+/-}5 (sham) nmol/g, P=0.02) and lungs (7.5{+/-}4 (TAC), 5.8{+/-}2 (sham) nmol/lung, P=0.17) of TAC mice corresponded to an increase in myocardial MRI %SI (29{+/-}15 (TAC), 6.1{+/-}4 (sham), P<0.0001) and {Delta}LMR (0.3{+/-}0.1 (TAC), 0.08{+/-}0.1 (sham), P<0.0001). Hyp in the heart (555{+/-}90 (TAC), 400{+/-}80 (sham) {micro}g/g, P<0.0001) and lungs (189{+/-}63 (TAC), 143{+/-}31 (sham) {micro}g/lung, P<0.01) were elevated in TAC mice, which corresponded to an increase in PET signal (MMR: 1.8{+/-}0.1 (TAC), 1.6{+/-}0.2 (sham), P=0.02; LMR: 1.5{+/-}0.1 (TAC), 1.2{+/-}0.1 (sham), P<0.001). PV loop and echocardiography demonstrated adverse LV remodeling, function, and increased right ventricular systolic pressure in TAC mice. ConclusionsAdministration of collagen-targeted PET and allysine-targeted MR probes led to elevated PET-MRI signals in the myocardium and lungs of TAC mice. The study demonstrates the potential to detect fibrosis and fibrogenesis in cardiopulmonary disease through a dual molecular PET-MR imaging protocol.

molecular biology↗