Loss of calprotectin impairs female protection from angiotensin II-induced hypertension, cardiac hypertrophy and vascular contractility

Premenopausal females are protected from angiotensin II (ANG II) induced hypertension compared to males. However, post-menopausal females lose protection against ANG II-induced hypertension that is associated with a proinflammatory phenotype. RNAseq studies identified higher expression of calprotectin (a proinflammatory protein associated with neutrophils) in female immune cells following ANG II. We hypothesized that loss of calprotectin will cause vascular dysfunction contributing to hypertension. Using global calprotectin knockouts (CalKO), we examined how loss of calprotectin impacts ANG II hypertension, cardiac hypertrophy, aortic function in a sex specific manner. Male and female wild type (WT) and calprotectin knockout (CalKO) mice were infused with ANG II (800 ng/kg/min; 14 days) via osmotic mini-pump. Systolic blood pressure (SBP) was assessed via tail cuff. Wire myography in aortic rings assessed vascular responses to acetylcholine (ACh), sodium nitroprusside (SNP), and phenylephrine (PE). Heart weight:tibia length (mg/mm) was used as an index of cardiac hypertrophy. In WT mice, ANG II induced a significant increase in SBP in male but not female mice (d14 ΔSBP: male/ANG II 34.7 ± 20.8 mmHg vs. WT female/ANG II 4.4 ± 13.4 mmHg). In contrast, in CalKO mice, ANG II induced a significant increase in SBP in both male and females (d14 ΔSBP CalKO male/ANG II 52.7 ± 19.1 mmHg; CalKO female/ANG II 22.4 ± 18.1 mmHg, p< 0.05). ANG II induced cardiac hypertrophy in WT males (WT 0.008 ± 0.001 vs. WT/ANG II 0.01 ± 0.003 mg/mm, p< 0.05) but not in WT females. In contrast, both CalKO males (CalKO 0.007 ± 0.001 vs. CalKO/ANG II 0.009 ± 0.002 mg/mm, p< 0.05) and CalKO females (CalKO 0.006 ± 0.001 vs. CalKO/ANG II 0.008 ± 0.002 mg/mm, p< 0.05) developed cardiac hypertrophy after ANG II. Wire myography on aortic rings revealed that baseline, CalKO females had an enhanced response to ACh compared to WT females and both WT and CalKO males (pEC50: CalKO female -7.4 ± 0.2, WT female -7.1 ± 0.2, CalKO male -6.9 ± 0.3, WT male -6.9 ± 0.3, p< 0.05). Following ANG II there was no difference in the ACh response in any group (pEC50: CalKO female/ANG II -7.5 ± 0.2, WT female/ANG II-7.0 ± 0.2, CalKO male/ANG II -6.9 ± 0.4, WT male/ANG II -6.8 ± 0.4). Moreover, there was no difference in the dose response to increasing concentrations of SNP at baseline (pEC50: WT male -7.4 ± 0.3, WT female -7.3 ± 0.2, CalKO male -7.4 ± 0.2, CalKO female -7.4 ± 0.1) or following ANG II (pEC50: WT male/ANG -7.3 ± 0.3, WT female/ANG -7.6 ± 0.3, CalKO male/ANG -7.2 ± 0.3, CalKO female/ANG -7.4 ± 0.1). ANG II infusion reduced the maximal response to PE in WT males (Emax WT 60 ± 14% vs. WT /ANG II 33 ± 10%, p< 0.05) and CalKO males (Emax CalKO 51 ± 24% vs. CalKO/ANG II 24 ± 14%, p< 0.05). In contrast, although aortic rings from WT females had a preserved maximal response to PE after ANG II infusion (Emax WT 51 ± 10% vs. WT/ANG II 50 ± 24%), aortas from CalKO females exhibited a reduced maximal response to PE (Emax CalKO 63 ± 20% vs. CalKO/ANG II 41 ± 11%, p< 0.05). We found a loss of calprotectin in females increased blood pressure in response to ANG II, effectively removing the sex difference observed in WT mice. Calprotectin deletion in females was also associated with increased cardiac hypertrophy. While aortic endothelial-dependent and -independent vasodilation were not impacted, calprotectin deletion enhanced the ACh response only in females. Moreover, ANG II impaired the PE response in all groups except WT females, which were protected from hypertension. This result suggests that calprotectin may be a critical modulator of female protection from ANG II hypertension. 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.