Increased Expressions of Toll-Like Receptor 4 on Platelet Are Related to Type of Bacteria and Disease Severity in Patients with Sepsis

Early diagnosis and treatment of patients with sepsis remain a common and severe problem, especially in leukopenic patients.. Toll-like receptor-4 (TLR4) plays a crucial role in immunity as the first defenses system against microbial infection through binding gram-negative bacterial LPS. Blood platelets are not only involved in hemostasis, they also have many features of classic inflammatory cells. The expression of TLR4 on platelet in patients with sepsis, including gram-positive bacteria and gram-negative bacteria, is not known. Studying the differences between them, we investigated whether the expressions of TLR4 on platelet were associated with platelet activation, serum TNF-a and endotoxin levels in patients with sepsis, 8 patients of them with gram-positive bacteria and 15 patients of them with gram-negative bacteria. The number of platelet and function of coagulation were normal before infecting. Comparing with the heath subjects, the expressions of TLR4 and P-selectin on platelets, the levels of serum TNF-a and endotoxin were higher (P<0.05),and there was a positive correlation was observed between TLR4 and P-selectin, TNF-a, endotoxin respectively, among the gram-negative bacterial subjects. The phenomena were not found among the gram-positive bacterial subjects. In addition, among the gram-negative bacterial subjects, the expression of TLR4 was higher in patients with decreased number of platelets than with normal number of platelets. These results suggest that increased TLR4 on platelet might be an important early sign of gram-negative bacteria in patient with sepsis, it contributes to platelet activating, the inflammatory process and disease activity in infecting host. Above has be doing in more patients with positive blood bacteria culture in our Lab.