Thrombin Inhibition Reduces the Expression of Brain Inflammation Markers upon Systemic LPS Treatment

Abstract

Systemic inflammation and brain pathologies are known to be linked. In the periphery, the inflammation and coagulation systems are simultaneously activated upon diseases and infections. Whether this well-established interrelation also counts for neuroinflammation and coagulation factor expression in the brain is still an open question. Our aim was to study whether the interrelationship between coagulation and inflammation factors may occur in the brain in the setting of systemic inflammation. The results indicate that systemic injections of lipopolysaccharide (LPS) upregulate the expression of both inflammatory and coagulation factors in the brain. The activity of the central coagulation factor thrombin was tested by a fluorescent method and found to be significantly elevated in the hippocampus following systemic LPS injection (0.5 ± 0.15 mU/mg versus 0.2 ± 0.03 mU/mg in the control). A panel of coagulation factors and effectors (such as thrombin, FX, PAR1, EPCR, and PC) was tested in the hippocampus, isolated microglia, and N9 microglia cell by Western blot and real-time PCR and found to be modulated by LPS. One central finding is a significant increase in FX expression level following LPS induction both in vivo in the hippocampus and in vitro in N9 microglia cell line (5.5 ± 0.6- and 2.3 ± 0.1-fold of increase, resp.). Surprisingly, inhibition of thrombin activity (by a specific inhibitor NAPAP) immediately after LPS injection results in a reduction of both the inflammatory (TNFα, CXL9, and CCL1; p < 0.006) and coagulation responses (FX and PAR1; p < 0.004) in the brain. We believe that these results may have a profound clinical impact as they might indicate that reducing coagulation activity in the setting of neurological diseases involving neuroinflammation may improve disease outcome and survival.

A Novel Highly Sensitive Method for Measuring Inflammatory Neural-Derived APC Activity in Glial Cell Lines, Mouse Brain and Human CSF

“…Systemic injection of LPS creates a general inflammatory response, including brain involvement. Elevated brain thrombin activity, together with PC and EPCR upregulation, following LPS injection has been previously described [36]. Thus, we expected to measure changes in APC activity following LPS injection.…”

Neurons, Glia, Extracellular Matrix and Neurovascular Unit: A Systems Biology Approach to the Complexity of Synaptic Plasticity in Health and Disease

“…Serpins and thrombomodulin are also considered NIRegs and could reduce the toxicity of thrombin on the CNS by preventing the canonical activation of PAR-1 [195]. LPS administration can stimulate production in the hippocampus of microglial inflammatory factors and the expression of coagulation factors, probably depending on thrombin signaling activation [196]. The relevance of these factors has been proved in neurological and psychiatric diseases [14].…”

Thrombin Inhibition by Argatroban: Potential Therapeutic Benefits in COVID-19

“…Along these lines, thrombin inhibition was found to reduce the expression of brain inflammatory markers upon systemic lipopolysaccharide treatment of mice. In this model, inhibition of thrombin activity by a specific inhibitor reported as NAPAP (mostly likely is dabigatran) immediately led to a reduction in the expression of inflammatory markers of TNF-α, C-X-C motif chemokine ligand-9 (CXL9), and C-C motif chemokine ligand-1 (CCL1) and in the expression of the coagulation markers of factor X and PAR-1 in the brain [ 53 ].…”

“…As mentioned before, lepirudin was found to prevent thrombin-mediated angiogenesis and to prevent thrombin-mediated expression of angiogenic growth factors [ 41 ]. Dabigatran reduced the expression of inflammatory markers of TNF-α, CXL9, and CCL1 and the expression of the coagulation markers of factor X and PAR-1 in mouse brain [ 53 ]. Dabigatran significantly inhibited PAR-1 activation, integrin αvβ6 induction, transforming growth factor-β activation, and the development of pulmonary fibrosis in a vascular-leak mouse model [ 64 ].…”