ADAM17-Mediated Cleavage of CD44 Impairs Hyaluronan-Dependent Shear Stress Mechanotransduction

Type 2 diabetes (T2D) is associated with endothelial dysfunction and reduced flow-mediated dilation (FMD), suggesting impaired shear stress mechanotransduction. Loss of endothelial glycocalyx components, particularly hyaluronan (HA), may contribute to this impairment. HA functions as a shear-stress mechanosensor through its membrane receptor CD44, which acts as a mechanotransducer. CD44 is also a substrate of a disintegrin and metalloproteinase-17 (ADAM17), a pro-inflammatory sheddase that cleaves multiple transmembrane proteins, and its expression and activity are known to increase in T2D. However, whether increased ADAM17 activity in T2D promotes CD44 cleavage and thereby impairs HA-dependent mechanotransduction is unknown. Therefore, we hypothesized that increased ADAM17 activity in T2D promotes CD44 cleavage and impairs HA-mediated sensing of shear stress. All data are reported as mean ± SEM, and statistical significance was set at P ≤ 0.05 for all analyses. In support of our hypothesis, we showed that individuals with T2D have blunted femoral artery FMD compared with age-matched healthy controls (n=19-26/group, peak FMD: 2.28±0.35 vs 4.77±0.58 %). Plasma ADAM17 activity and soluble HA concentrations were also higher in T2D (1.56±0.03 and 1.24±0.07 fold, respectively). Consistent with the observations in humans, compared to wild-type mice, db/db mice exhibited reduced FMD in mesenteric arteries (n=4/group, 43.2±7.97 vs. 78.4±4.68 %), increased endothelial ADAM17 expression (n=5/group, 1.39±0.09 fold), and decreased endothelial CD44 content (n=9-10/group, 0.62±0.04 fold). We also demonstrate that degradation of HA with intraluminal hyaluronidase (15µg/mL, 1hr) reduced FMD in isolated mesenteric arteries (n=6/9, 40.9±7.33 vs. 61.8±12.4 %), without affecting endothelium-independent vasodilation. Furthermore, in CD44-deficient live cells, acute shear-induced increases in intracellular Ca 2+ were attenuated (15dyn/cm2, 5min, n=3-4, 1.27±0.05 vs. 1.15±0.03 fold change). Similarly, blockade of the HA-binding site on CD44 using the anti-mouse CD44-LE/AF KM201 antibody (0.25mg/mL, 1hr) impaired FMD ex vivo (n=7-8, 27.9±9 vs. 54.6±8.8 %), supporting a mechanistic role for CD44 in HA-dependent shear sensing. Notably, ADAM17 overexpression reduced surface CD44 levels (0.66±0.03 fold) and attenuated shear-induced Ca 2+ elevations (15dyn/cm2, 5min, 1.03±0.01 vs. 1.10±0.02 fold change). Using surface plasmon resonance, we found that active recombinant ADAM17 (5ng/µL, 8hr) reduced HA binding to CD44 (0.94±0.02 fold), and intraluminal incubation of isolated arteries with recombinant ADAM17 (1µg/mL, 1hr) similarly impaired FMD (n=6-7, 22.1±6.54 vs. 44.5±11.3 %) without altering endothelium-independent vasodilation. Taken together, these data suggest that ADAM17-mediated CD44 cleavage is a potential mechanism contributing to impaired HA-dependent mechanotransduction of shear stress. This ADAM17-CD44-HA axis may represent a novel pathway underlying endothelial dysfunction in T2D. Funding: This work is supported, in part, by the National Institutes of Health Grants R01HL151384 (to LAM-L and JP), R01HL137769 (to JP), R21DK116081 (to CM-A), the Veterans Affairs Merit Grant 1I01CX002399 (to CM-A and JP), and grants from the American Heart Association (23PRE1020897 to GP, 25DIVSUP1463861 to FIR-P, and 24EIA1248820 to JP) and the São Paulo Research Foundation (FAPESP, 2024/09267-4 to LF-S) This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.