Patients with comorbidities such as hypertension, obesity, and diabetes had elevated DPPIV, MMP-8, and TIMP-4 levels, and reduced MMP-3 and TIMP-2 levels, indicating a link between these markers and the exacerbating effects of comorbidities on COVID-19 outcomes (Figure 5D, Supplementary Figure S17). Here, DPP4 is linked to COVID-19.