The role of bone marrow-derived cells in venous thromboembolism

Neutrophil Extracellular Traps: Potential Prothrombotic State Markers and Therapeutic Targets for Atrial Fibrillation

BACKGROUND

 Recently, the mechanism of thrombogenesis has taken a new direction with the involvement of neutrophil extracellular traps (NETs). However, little is known about the relationship between NETs and thrombogenesis in atrial fibrillation (AF).

OBJECTIVE

 Our study aimed to evaluate NETs in AF patients and their potential association with thrombogenesis. In addition, we studied the effect of NETs on thrombogenesis in rat models.

METHODS

 A total of 125 AF patients and 172 controls were studied. Spontaneous echo contrast (SEC) was examined using transesophageal echocardiography to assess the prothrombotic state. We used rapid atrial pacing (RAP) rat models to study NETs' formation and their effects on thrombogenesis. The levels of NETs were analyzed by flow cytometry. To deeply understand the regulatory mechanism of NET formation, the transcriptional characteristics of the left atrial appendage (LAA) tissue from RAP rats were analyzed.

RESULTS

 We found that NETs were increased significantly in AF patients and positively correlated with SEC grades. And inserting the NET level could significantly enhance the predictivity of CHA2DS2-VASc scores for the AF prothrombotic state. In the RAP models, we observed that NET levels increased significantly in the LAA and promoted thrombosis. Meanwhile, we found that these changes could be suppressed by the NET formation inhibitor. Transcriptomic analysis of the LAA tissue from RAP rats suggested that RAP might stimulate the NET formation by promoting the expression of inflammatory cytokine and adhesion genes.

CONCLUSION

 NETs may constitute useful thrombogenesis risk markers in AF patients and provide a potential therapeutic strategy for AF management.

Change in cytokine profiles released by mast cells mediated by lung cancer-derived exosome activation may contribute to cancer-associated coagulation disorders

BACKGROUND

Coagulation disorders are a significant cause of lung cancer mortality. Although mast cells are known to play a role in coagulation abnormalities, their specific role in this process has not yet been elucidated.

METHOD

We detected mast cells in the tumor microenvironment using single-cell sequencing data and examined their correlation with thrombosis-related genes, neutrophil-related genes, neutrophil extracellular trap-related signature genes, and immune infiltration levels in lung cancer patients through bioinformatics analysis. Bone marrow mast cell uptake of exosomes isolated from the lung adenocarcinoma cell line A549, which were labeled using PKH67, was observed using confocal microscopy. Mast cell degranulation was detected by measuring the β-hexosaminidase release rate. Additionally, cytokine array analysis was performed to identify altered mediators released by bone marrow mast cells after uptake of the exosomes.

RESULTS

In our study, we found a close correlation between the proportion of mast cells in lung cancer patients and the expression levels of thrombosis-related genes and neutrophil extracellular trap signature genes, both of which play a key role in thrombophilic disorder. Moreover, we discovered that lung cancer cell-derived exosomes can be taken up by mast cells, which in turn become activated to release procoagulant mediators.

CONCLUSION

Our study shows that exosomes derived from lung cancer cells can activate mast cells to release procoagulants that may contribute to abnormal blood clotting in lung cancer patients. Video Abstract.

Thromboembolic Adverse Drug Reactions in Janus Kinase (JAK) Inhibitors: Does the Inhibitor Specificity Play a Role?

Recent advances in immunology enabled the characterization of several signal transmitting pathways responsible for proper cytokine and chemokine signaling. Among them, Janus kinases (JAKs) are essential components of receptor activation systems. The discovery of JAK kinases enabled the synthesis of JAK kinase inhibitors (JAKi or Jakinibs), which have proven to be efficacious in the treatment of hematologic malignancies and several rheumatological disorders and continue to be investigated in many clinical indications. Blocking multiple cytokines belonging to several cytokine families with a single small molecule may, however, create a potential risk for the patients. Recently, a higher risk of thromboembolic complications, namely, deep vein thrombosis and pulmonary embolism, has been recognized as the main concern during treatment with Jakinibs. At present, it is not entirely clear whether this increased risk is related to direct cytokine blockade, the presence of concomitant diseases in treated patients or other unknown circumstances that work together to increase the risk of this side effect. In this review, we discuss data on the risk of thromboembolic side effects, with special emphasis on the mechanism that may be responsible for this increased risk. Many indirect data indicate that higher thromboembolic risk may be related to the specificity of JAK inhibitor action, such that preferentially blocking one signaling pathway upsets the balance between pro and anti-thrombotic activities.