Platelet-Dependent Inflammatory Dysregulation in Patients with Stages 4 or 5 Chronic Kidney Disease: A Mechanistic Clinical Study

Background: Chronic kidney disease (CKD) is characterized by dysregulated inflammation that worsens with CKD severity. The role of platelets in modulating inflammation in stage 4 or 5 CKD remains unexplored. We investigated whether there are changes in platelet-derived thromboinflammatory markers in CKD with dual antiplatelet therapy (DAPT; aspirin 81 mg/d plus P2Y12 inhibitor).

Methods: In a mechanistic clinical trial, we compared platelet activation markers (aggregation and surface receptor expression), circulating platelet-leukocyte aggregates, leukocyte composition (monocyte subtypes and CD11b surface expression), and plasma cytokine profile (45 analytes) of non-CKD controls (n=26) and CKD outpatients (n=48) with a glomerular filtration rate (GFR) <30 ml/min per 1.73 m² on 2 weeks of DAPT.

Results: Patients with CKD demonstrated a reduced mean platelet count, elevated mean platelet volume, reduced platelet-leukocyte aggregates, reduced platelet-bound monocytes, higher total non-classic monocytes in the circulation, and higher levels of IL-1RA, VEGF, and fractalkine (all P<0.05). There were no differences in platelet activation markers between CKD and controls. Although DAPT reduced platelet aggregation in both groups, it had multifaceted effects on thromboinflammatory markers in CKD, including a reduction in PDGF levels in all CKD individuals, reductions in IL-1β and TNF-α levels in select CKD individuals, and no change in a number of other cytokines. Significant positive correlations existed for baseline IL-1β, PDGF, and TNF-α levels with older age, and for baseline TNF-α levels with presence of diabetes mellitus and worse albuminuria. Mean change in IL-1β and PDGF levels on DAPT positively correlated with younger age, mean change in TNF-α levels with higher GFR, and mean changes in PDGF, and TRAIL levels correlated with worse albuminuria. Minimum spanning trees plot of cytokines showed platelet-derived CD40L had a large reduction in weight factor after DAPT in CKD. Additionally, platelet-derived IL-1β and PDGF were tightly correlated with other cytokines, with IL-1β as the hub cytokine.

Conclusions: Attenuated interactions between platelets and leukocytes in the CKD state coincided with no change in platelet activation status, an altered differentiation state of monocytes, and heightened inflammatory markers. Platelet-derived cytokines were one of the central cytokines in patients with CKD that were tightly correlated with others. DAPT had multifaceted effects on thromboinflammation, suggesting that there is platelet-dependent and -independent inflammation in stage 4 or 5 CKD.