Anti-factor Xa level monitoring of low-molecular-weight heparin for prevention of venous thromboembolism in critically ill patients (AXaLPE): protocol of a randomised, open-label controlled clinical trial.

INTRODUCTION: Whether and when to monitor the amount of anti-factor Xa (aFXa) activity in critically ill patients with complex diseases to prevent venous thromboembolism (VTE) remain unclear. This study is a randomised controlled trial to investigate the effect of aFXa level monitoring on reducing VTE and to establish a new method for accurately preventing VTE in critically ill patients with low-molecular-weight heparin (LMWH). METHODS AND ANALYSIS: A randomised controlled trial is planned in two centres with a planned sample size of 858 participants. Participants will be randomly assigned to three groups receiving LMWH prophylaxis at a 1:1:1 ratio: in group A, peak aFXa levels will serve as the guide for the LMWH dose; in group B, the trough aFXa levels will serve as the guide for the LMWH dose; and in group C, participants serving as the control group will receive a fixed dose of LMWH. The peak and trough aFXa levels will be monitored after LMWH (enoxaparin, 40 mg, once daily) reaches a steady state for at least 3 days. The monitoring range for group A's aFXa peak value will be 0.3-0.5 IU/mL, between 0.1 and 0.2 IU/mL is the target range for group B's aFXa trough value. In order to reach the peak or trough aFXa levels, groups A and B will be modified in accordance with the monitoring peak and trough aFXa level. The incidence of VTE will serve as the study's primary outcome indicator. An analysis using the intention-to-treat and per-protocol criterion will serve as the main outcome measurement. ETHICS AND DISSEMINATION: The Xuanwu Hospital Ethics Committee of Capital Medical University and Peking University First Hospital Ethics Committee have approved this investigation. It will be released in all available worldwide, open-access, peer-reviewed publications. TRIAL REGISTRATION NUMBER: NCT05382481.

CKII-SIRT1-SM22α loop evokes a self-limited inflammatory response in vascular smooth muscle cells.

AIMS: Sirtuin 1 (SIRT1) inhibits nuclear factor kappa B (NF-κB) activity in response to the inflammatory cytokine tumour necrosis factor alpha (TNF-α). Smooth muscle (SM) 22α is a phosphorylation-regulated suppressor of IKK-IκBα-NF-κB signalling cascades in vascular smooth muscle cells (VSMCs). Sm22α knockout results in increased expression of pro-inflammatory genes in the aortas which are controlled by NF-κB. This study aimed to investigate the relationship between SM22α and SIRT1 in the control of vascular inflammation. METHODS AND RESULTS: The ligation injury model of Sirt1-Tg/Sm22α-/- mice displayed an increased level of the inflammatory molecules in the carotid arteries compared with Sirt1-Tg mice, accompanied with aggravating neointimal hyperplasia. In the in vitro study, on the one hand, we showed that TNF-α induced the epigenetic silencing of SM22α transcription via EZH2-mediated H3K27 methylation in the SM22α promoter region, contributing to inflammatory response. On the other hand, TNF-α simultaneously induced SIRT1 phosphorylation via CKII and thereby protected against inflammation. Phosphorylated SIRT1 interacted with and deacetylated EZH2 and, subsequently, promoted SM22α transcription by inhibiting EZH2 activity. Increased SM22α in turn facilitated the phosphorylation and activation of SIRT1 via recruitment of CKII to SIRT1, which amplified the anti-inflammatory effect of SIRT1. CONCLUSION: Our findings demonstrate that, in response to TNF-α stimulation, CKII-SIRT1-SM22α acts in a loop to reinforce the expression of SM22α, which limits the inflammatory response in VSMCs in vivo and in vitro. The anti-inflammatory effect of SIRT1 may be dependent on SM22α to some extent. Our data point to targeted activation of SIRT1 in VSMCs as a promising therapeutic avenue in preventing cardiovascular diseases.