Biology subjects

Combadiere, C.

Publications and source records attributed to Combadiere, C..

3 recordsLinked to original sources

bioRxiv2020

Chemokine receptor 2-targeted molecular imaging in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, inflammatory lung disease that is monitored clinically by measures of lung function, without effective molecular markers of disease activity or therapeutic efficacy. Lung immune cells active in the pro-fibrotic process include inflammatory monocyte and interstitial macrophages that express the C-C motif chemokine receptor 2 (CCR2). CCR2+ monocyte lung influx is essential for disease phenotypes in models of fibrosis and identified in lungs from subjects with IPF. Here, we show that our peptide-based radiotracer 64Cu-DOTA-ECL1i identifies CCR2+ inflammatory monocytes and interstitial macrophages in multiple preclinical mouse models of lung fibrosis, using positron emission tomography (PET) imaging. Mice with bleomycin-induced fibrosis treated with blocking antibodies to interleukin-1{beta}, a mediator of fibrosis associated with CCR2+ cell inflammation, or with pirfenidone, an approved anti-fibrotic agent, demonstrated decreased CCR2-dependent interstitial macrophage accumulation and reduced 64Cu-DOTA-ECL1i PET uptake, compared to controls. Lung tissues from patients with fibrotic lung disease demonstrated abundant CCR2+ cells surrounding regions of fibrosis, and an ex vivo tissue-binding assay showed correlation between radiotracer localization and CCR2+ cells. In a phase 0/1 clinical study of 64Cu-DOTA-ECL1i PET, healthy volunteers showed little lung uptake, while subjects with pulmonary fibrosis exhibited increased uptake, notably in zones of subpleural fibrosis, reflecting the distribution of CCR2+ cells in the profibrotic niche. These findings support a pathologic role of inflammatory lung monocytes/macrophages in fibrotic lung disease and the translational use of 64Cu-DOTA-ECL1i PET to track CCR2-specific inflammation for image-guided therapy. One Sentence SummaryPET imaging of CCR2+ cells in lung fibrosis identifies a therapeutic response in mouse models and displays a perifibrotic signal in subjects with IPF.

cell biology↗

bioRxiv2020

Revising CX3CR1 expression on murine classical and non-classical monocytes

In mice, monocytes (Mo) are conventionally described as CX3CR1low classical Mo (CMo) and CX3CR1high non-classical Mo (NCMo) based on the expression level of EGFP in Cx3cr1+/EGFP mice and by analogy with human CX3CR1 expression. Although this terminology is widely used, very few works assessed the strict correlation between EGFP reporter and CX3CR1 expression. Using an unsupervised multiparametric analysis of blood Mo in steady state and after sterile peritonitis, we observed no difference in CX3CR1 expression between CMo and NCMo. Our results highlight that despite being a reliable reporter to discriminate Mo subpopulations, EGFP level in Cx3cr1+/EGFP mice does not reflect CX3CR1 expression measured by a fluorescently-labeled CX3CL1 chemokine and a CX3CR1 specific antibody. In conclusion, authors should be cautious not to identify murine classical and non-classical Mo as CX3CR1low and CX3CR1high but rather use alternative markers such as the combination of Ly6C and CD43.

immunology↗

bioRxiv2019

CX3CL1 oligomerization is required for efficient CX3CR1-specific cell adherence

During inflammatory response, blood leukocytes adhere to the endothelium. This process involves numerous adhesion molecules, including a transmembrane chemokine, CX3CL1. We previously found that CX3CL1 clusters in oligomers. How this cluster assembles and whether it has a functional role remain unknown. Using various biochemical and biophysical approaches, we show that CX3CL1 clusters are homo-oligomers with 3 to 7 CX3CL1 molecules. We demonstrate that the transmembrane domain peptide self-associates at a similar level in both cellular and acellular lipid environments while its random counterpart (a scrambled peptide) does not. Hence, oligomerization is mainly driven by the transmembrane domain intrinsic properties. Molecular modeling suggests that transmembrane peptide oligomers are mostly made of monomers linearly assembled side by side. Using a new adherence assay, we demonstrate that, functionally, oligomerization is mandatory for the adhesive potency of CX3CL1. Our results indicate that CX3CL1-dependent cellular adherence in key immune processes can be controlled by disrupting clusters using heterotopic peptides, which, in turn, alter the adhesive function of the membrane CX3CL1 without affecting the function of the CX3CL1 soluble form.

cell biology↗