Vascular Immune Crosstalk in COVID-19: RAAS Biomarker Signature Linking Angiotensin II to Respiratory Compromise and Soluble ACE2 to IL-13 and FGF, Revealing Therapeutic Targets

COVID-19 perturbs the renin-angiotensin system (RAAS) and inflammatory pathways, shaping disease severity. Soluble ACE2 (sACE2) and angiotensin II (Ang II) are central regulators of vascular and immune homeostasis. We profiled plasma from COVID-19 patients and controls using ELISA, together with 48 cytokine profiling and clinical data. Both sACE2 and Ang II were significantly elevated in patients. Increased Ang II was associated with oxygen supplementation and dyspnea, and negatively correlated with IL-3, whereas sACE2 correlated with IL-13 and FGF. Comorbidities modulated cytokine expression: diabetes mellitus was linked to reduced LIF and MCP-1, hypertension to decreased LIF and increased IP-10, and obesity to elevated IL-12p70. Age correlated with TNF and HGF, and reduced oxygen saturation was associated with lower LIF. These findings reveal that acute COVID-19 disrupts RAAS and amplifies immune dysregulation, with Ang II emerging as a pivotal mediator of respiratory compromise and inflammatory imbalance, underscoring its potential as a biomarker and therapeutic relevance.