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Introduction Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by autoantibodies directed against G protein-coupled receptors (GPCRs) such as the angiotensin II type 1 receptor (AT1R). These autoantibodies contribute to endothelial activation, dysfunction, and subsequent vascular inflammation and fibrosis. In this study, we explore how AT1R-targeting antibodies influence the endothelial glycocalyx (eGC), a crucial regulator of vascular health, whose degradation is known to impair endothelial function and facilitate monocyte adhesion.Material and Methods Primary human umbilical vein endothelial cells (HUVECs) were isolated from human umbilical cords and cultured to confluence. Cells underwent a 24-hour treatment with either angiotensin II (Ang II), the natural agonist of AT1R, or a recombinant AT1R-specific monoclonal antibody (mAb) at 50 µg/mL. We measured changes in eGC height using atomic force microscopy (AFM) coupled with a nanoindentation approach. To determine if eGC impairment affects monocyte recruitment, U937 monocyte-like cells were fluorescently labeled with Calcein AM, incubated with treated HUVECs for 30 minutes, and then analyzed via fluorescence microscopy to quantify adhesion.Results Both Ang II and the AT1R-monoclonal antibody significantly reduced the eGC height: Ang II by a median of 17.18% (p = 0.0014) and AT1R-mAb by 25.09% (p < 0.0001) relative to untreated controls. The eGC reduction was prevented by co-treatment with losartan, confirming that the effect is AT1R-dependent. Despite these mechanical and structural changes in the eGC, static adhesion assays showed no meaningful increase in U937 cell adhesion following AT1R-mAb treatment.Conclusions Our data indicate that AT1R-specific autoantibodies, akin to Ang II, can damage the eGC and thereby support endothelial dysfunction in SSc. However, the absence of enhanced monocyte adhesion under static culture conditions suggests that eGC disruption alone is not sufficient to recruit immune cells. This implies that additional pro-inflammatory signals or biomechanical forces present in vivo may be required to facilitate leukocyte-endothelium interactions in SSc.