Fibronectin fibers are highly tensed in healthy organs in contrast to tumors and virus-infected lymph nodes

The extracellular matrix (ECM) acts as reservoir for a plethora of growth factors and cytokines some of which are hypothesized to be regulated by ECM fiber tension. Yet, ECM fiber tension has never been mapped in healthy versus diseased organs. Using our recently developed tension nanoprobe derived from the bacterial adhesin FnBPA5, which preferentially binds to structurally relaxed fibronectin fibers, we discovered here that fibronectin fibers are kept under high tension in selected healthy mouse organs. In contrast, tumor tissues and virus-infected lymph nodes exhibited a significantly higher content of relaxed or proteolytically cleaved fibronectin fibers. This demonstrates for the first time that the tension of ECM fibers is significantly reduced upon pathological tissue transformations. This has wide implications, as the active stretching of fibronectin fibers adjusts critical cellular niche parameters and thereby tunes the reciprocal cell-ECM crosstalk. Mapping the tensional state of fibronectin fibers opens novel and unexpected diagnostic opportunities.

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Mechanobiology of extracellular matrix changes upon pathological transformations.

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Fibronectin is significantly more relaxed in tumors than in healthy organs.

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Relaxed fibronectin is found close to myofibroblasts and dense collagen fibers.

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Viral infection reduces fibronectin fiber tension in lymph nodes.

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Use of a tension-sensitive adhesin to probe fibronectin fiber tension in tissues