Advances in attractive therapeutic approach for macrophage activation syndrome in COVID-19.

Nowadays, people have relaxed their vigilance against COVID-19 due to its declining infection numbers and attenuated virulence. However, COVID-19 still needs to be concern due to its emerging variants, the relaxation of restrictions as well as breakthrough infections. During the period of the COVID-19 infection, the imbalanced and hyper-responsive immune system plays a critical role in its pathogenesis. Macrophage Activation Syndrome (MAS) is a fatal complication of immune system disease, which is caused by the excessive activation and proliferation of macrophages and cytotoxic T cells (CTL). COVID-19-related hyperinflammation shares common clinical features with the above MAS symptoms, such as hypercytokinemia, hyperferritinemia, and coagulopathy. In MAS, immune exhaustion or defective anti-viral responses leads to the inadequate cytolytic capacity of CTL which contributes to prolonged interaction between CTL, APCs and macrophages. It is possible that the same process also occurred in COVID-19 patients, and further led to a cytokine storm confined to the lungs. It is associated with the poor prognosis of severe patients such as multiple organ failure and even death. The main difference of cytokine storm is that in COVID-19 pneumonia is mainly the specific damage of the lung, while in MAS is easy to develop into a systemic. The attractive therapeutic approach to prevent MAS in COVID-19 mainly includes antiviral, antibiotics, convalescent plasma (CP) therapy and hemadsorption, extensive immunosuppressive agents, and cytokine-targeted therapies. Here, we discuss the role of the therapeutic approaches mentioned above in the two diseases. And we found that the treatment effect of the same therapeutic approach is different.

Immune checkpoint molecule Tim-3 promotes NKT cell apoptosis and predicts poorer prognosis in Sepsis.

BACKGROUND: Sepsis is a leading cause of death among critically ill patients, which is defined as life-threatening organ dysfunction caused by a deregulated host immune response to infection. Immune checkpoint molecule Tim-3 plays important and complex roles in regulating immune responses and in inducing immune tolerance. Although immune checkpoint blockade would be expected as a promising therapeutic strategy for sepsis, but the underlying mechanism remain unknown, especially under clinical conditions. METHODS: Tim-3 expression and apoptosis in NKT cells were compared in septic patients (27 patients with sepsis and 28 patients with septic shock). Phenotypic and functional characterization of Tim-3+ NKT cells were analysed, and then the relationship between Tim-3 + NKT cells and clinical prognosis were investigated in septic patients. α-lactose (Tim-3/Galectin-9 signalling inhibitor) and Tim-3 mutant mice (targeting mutation of the Tim-3 cytoplasmic domain) were utilized to evaluate the protective effect of Tim-3 signalling blockade following septic challenge. RESULTS: There is a close correlation between Tim-3 expression and the functional status of NKT cells in septic patients, Upregulated Tim-3 expression promoted NKT cell activation and apoptosis during the early stage of sepsis, and it was associated with worse disease severity and poorer prognosis in septic patients. Blockade of the Tim-3/Galectin-9 signal axis using α-lactose inhibited in vitro apoptosis of NKT cells isolated from septic patients. Impaired activity of Tim-3 protected mice following septic challenge. CONCLUSIONS: Overall, these findings demonstrated that immune checkpoint molecule Tim-3 in NKT cells plays a critical role in the immunopathogenesis of septic patients. Blockade of immune checkpoint molecule Tim-3 may be a promising immunomodulatory strategy in future clinical practice for the management of sepsis.

Multifactorial Shock: A Neglected Situation in Polytrauma Patients.

Background: Shock after traumatic injury is likely to be hypovolemic, but different types of shock (distributive shock, obstructive shock, or cardiogenic shock) can occur in combination, known as multifactorial shock. Multifactorial shock is a neglected area of study, and is only reported sporadically. Little is known about the incidence, characteristics, and outcomes of multifactorial shock after polytrauma. Methods: A retrospective, observational, multicenter study was conducted in four Level I trauma centers involving 1051 polytrauma patients from June 2020 to April 2022. Results: The mean Injury Severity Score (ISS) was 31.1, indicating a severely injured population. The most common type of shock in the early phase after polytrauma (≤48 h) is hypovolemic shock (83.2%), followed by distributive shock (14.4%), obstructive shock (8.7%), and cardiogenic shock (3.8%). In the middle phase after polytrauma (>48 h or ≤14 days), the most common type of shock is distributive shock (70.7%), followed by hypovolemic shock (27.2%), obstructive shock (9.9%), and cardiogenic shock (7.2%). Multifactorial shock accounted for 9.7% of the entire shock population in the early phase and 15.2% in the middle phase. In total, seven combinations of multifactorial shock were described. Patients with multifactorial shock have a significantly higher complication rate and mortality than those with single-factor shock. Conclusions: This study characterizes the incidence of various types of shock in different phases after polytrauma and emphasizes that different types of shock can occur simultaneously or sequentially in polytrauma patients. Multifactorial shock has a relatively high incidence and mortality in polytrauma patients, and trauma specialists should be alert to the possibility of their occurrence.

Activated autophagy of innate immune cells during the early stages of major trauma.

Background: Trauma-induced immune dysfunction has been a major barrier to achieving reduced mortality, which is poorly understood. Autophagy is a crucial catabolic mechanism of immune cells during times of stress. Few studies have investigated the immune regulatory effects induced by autophagy after trauma. Here, we use single-cell transcriptomics analysis in a major trauma cohort to demonstrate the dominant role of autophagy in innate immune cells during the early stages of major trauma. Method: Single-cell transcriptional profiling of peripheral blood mononuclear cells (PBMCs) was performed, which were sampled from three control participants and five major trauma patients within 6 hours of injury. In detail, after single-cell RNA-sequence data processing, cell type annotation and cluster marker identification were performed. A genetic toolbox with 604 autophagy-related genes was used to monitor the autophagy levels in immune cells. In addition, all transcriptome RNA sequencing data obtained from PBMCs in a cohort of 167 major trauma patients were downloaded from gene expression omnibus (GEO) datasets (GSE36809). Key deregulated biological processes and important autophagic hub genes involved in immune cells were identified by weighted gene co-expression network analysis and gene ontology enrichment analysis. Results: A total of 20,445 differentially expressed genes were identified and five co-expression modules were constructed. Enrichment analysis indicated that activated autophagy is the most important biological process during the early stages of major trauma, and JMY (autophagy-related genes) were identified as hub genes. The single-cell transcriptional profiling of PBMCs demonstrated that all components of adaptive immune cells were significantly decreased, whereas components of innate immune cells (monocytes and neutrophils) were significantly increased in major trauma patients compared with control participants. Activated autophagy was detected in monocytes and neutrophils by monitoring the dynamic transcriptional signature of the autophagy-related genetic toolbox. Biological process analysis shows that antigen uptake, processing presentation, and major histocompatibility complex (MHC) class II protein complex assembly pathways were up-regulated in autophagy-positive monocytes, whereas antigen processing and presentation of endogenous antigen and type I interferon signaling pathways were up-regulated in autophagy-positive neutrophils during the early stages of major trauma. Conclusion: Our study demonstrated that autophagy is a biological process crucial to the development of immune disorders in the early stages of major trauma. Furthermore, the results of our study generated a comprehensive single-cell immune landscape for major trauma patients, in which we determined that autophagy profoundly affects the main functions of innate immune cells and provides insight into the cellular basis of immune dysregulation after major trauma.