Monocyte Dynamics in Chikungunya Fever: Sustained Activation and Vascular-Coagulation Pathway Involvement

Chikungunya fever (CF), caused by the Chikungunya virus (CHIKV), is characterized by disabling symptoms such as joint pain that can last for months. Monocytes play a central role in immune modulation and viral replication during infection. This study evaluated the clinical and immunological profiles of patients with laboratory-confirmed CF. Fever and joint pain were the most frequently reported symptoms, whereas edema was more common in women. CHIKV-infect individuals exhibited increased TLR4 expression in non-classical monocytes (CD14+CD16++). Additionally, intermediate (CD14+CD16+) and non-classical (CD14+CD16++) monocytes expressing TLR7 were enriched during the acute phase and in some chronic patients, thereby suggest prolonged TLR7 pathway activation. Levels of soluble CD163 (sCD163)—a marker of monocyte/macrophage activation—were elevated as well, indicating sustained immune activation. Coagulation-related mediators—including Tissue factor (TF) and Tissue factor pathway inhibitor (TFPI)—also increased, despite the rarity of hemorrhagic events or thrombocytopenia. Patients with arthritis demonstrated higher frequencies of TLR7+ intermediate monocytes and elevated Epidermal growth factor (EGF) levels, whereas those with edema exhibit increased Vascular endothelial growth factor (VEGF) levels. Overall, these findings highlighted the differential activation of CD16+ monocytes and suggested that sCD163 is a marker of monocyte/macrophage activation during CHIKV infection.