Expression and Clinical Correlations of Costimulatory Molecules on Peripheral T Lymphocyte Subsets of Early-Stage Severe Sepsis: A Prospective Observational Study

Establishment and assessment of mortality risk prediction model in patients with sepsis based on early-stage peripheral lymphocyte subsets

This study is aimed to explore the value of lymphocyte subsets in evaluating the severity and prognosis of sepsis. The counts of lymphocytes, CD3+ T cells, CD4+ T cells, CD8+ T cells, CD19+ B cells, and NK cells significantly decreased between day 1 and day 3 in both the survivor and the non-survivor groups. The peripheral lymphocyte subsets (PLS) at day 1 were not significantly different between the survivor and the non-survivor groups. However, at day 3, the counts of lymphocytes, CD3+ T cells, CD4+ T cells, and NK cells were remarkably lower in the non-survivor group. No significant differences in CD8+ T cells, or CD19+ B cells were observed. The PLS index was independently and significantly associated with the 28-day mortality risk in septic patients (OR: 3.08, 95% CI: 1.18-9.67). Based on these clinical parameters and the PLS index, we developed a nomograph for evaluating the individual mortality risk in sepsis. The area under the curve of prediction with the PLS index was significantly higher than that from the model with only clinical parameters (0.912 vs. 0.817). Our study suggests that the decline of PLS occurred in the early stage of sepsis. The new novel PLS index can be an independent predictor of 28-day mortality in septic patients. The prediction model based on clinical parameters and the PLS index has relatively high predicting ability.

Insight Into Regulatory T Cells in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a diffuse central nervous system (CNS) dysfunction during sepsis, and is associated with increased mortality and poor outcomes in septic patients. Despite the high incidence and clinical relevance, the exact mechanisms driving SAE pathogenesis are not yet fully understood, and no specific therapeutic strategies are available. Regulatory T cells (T_regs) have a role in SAE pathogenesis, thought to be related with alleviation of sepsis-induced hyper-inflammation and immune responses, promotion of T helper (Th) 2 cells functional shift, neuroinflammation resolution, improvement of the blood-brain barrier (BBB) function, among others. Moreover, in a clinical point of view, these cells have the potential value of improving neurological and psychiatric/mental symptoms in SAE patients. This review aims to provide a general overview of SAE from its initial clinical presentation to long-term cognitive impairment and summarizes the main features of its pathogenesis. Additionally, a detailed overview on the main mechanisms by which T_regs may impact SAE pathogenesis is given. Finally, and considering that T_regs may be a novel target for immunomodulatory intervention in SAE, different therapeutic options, aiming to boost peripheral and brain infiltration of T_regs, are discussed.

Regulatory T Cells: Angels or Demons in the Pathophysiology of Sepsis?

Sepsis is a syndrome characterized by life-threatening organ dysfunction caused by the dysregulated host response to an infection. Sepsis, especially septic shock and multiple organ dysfunction is a medical emergency associated with high morbidity, high mortality, and prolonged after-effects. Over the past 20 years, regulatory T cells (Tregs) have been a key topic of focus in all stages of sepsis research. Tregs play a controversial role in sepsis based on their heterogeneous characteristics, complex organ/tissue-specific patterns in the host, the multi-dimensional heterogeneous syndrome of sepsis, the different types of pathogenic microbiology, and even different types of laboratory research models and clinical research methods. In the context of sepsis, Tregs may be considered both angels and demons. We propose that the symptoms and signs of sepsis can be attenuated by regulating Tregs. This review summarizes the controversial roles and Treg checkpoints in sepsis.

A new indicator: The diagnostic value of CD8+T/B lymphocyte ratio in sepsis progression

Objective

To reveal the value of single lymphocyte subpopulation and their ratios in the progression of sepsis.

Methods

From January 2019 to March 2021, 39 sepsis patients, 16 septic shock patients, and 50 healthy volunteers were recruited in the Second Xiangya Hospital for this cross-sectional study. The absolute quantitation of CD4+T, CD8+T, B lymphocytes, and NK cells in peripheral blood were determined by flow cytometry. SPSS Software was used to analyze the results.

Results

On the whole, the numbers of lymphocytes in the sepsis group and in the septic shock group were lower than that in the healthy control group. Surprisingly, the percentage of CD8+T lymphocytes in the septic shock group was slightly higher than that in the sepsis group. The percentage of B lymphocytes in the sepsis group was higher than that in the healthy control group. The AUC of CD8+T/B was 0.724, with the sensitivity and specificity being 75.00% and 71.79%, respectively.

Conclusion

The immune expression pattern of patients with sepsis was not a simple decrease in the number of lymphocytes. The change in the ratios of lymphocyte subpopulation might be more meaningful along the development and progression of sepsis. The ratio of CD8+T/B could be used to diagnose the progression of sepsis and reduce the misdiagnosis rate to a certain extent.

PD-1 in Tregs predicts the survival in sepsis patients using sepsis-3 criteria: A prospective, two-stage study

BACKGROUND

The expression of Tregs co-signaling molecules serves as the marker of immune dysfunction. The present study aimed to verify their predictive role in the 28-day mortality of sepsis patients.

METHODS

A prospective, observational, two-stage cohort study was conducted. The patients who fulfilled the sepsis-3 criteria were enrolled, and peripheral blood samples were collected within 24 h post-enrollment. The expression of the four co-signaling molecules of Tregs, namely, PD-1, CD28, PD-L1 and CD86, was measured, and sequential organ failure assessment (SOFA) scores were recorded on day 1 of inclusion. Patients were followed up for 28 days or, otherwise, deceased. Multivariate regression analysis was used to assess the independent risk factors for 28-day mortality, and a prognostic prediction model was established, which was verified in the validation set.

RESULTS

A total of 292 patients were recruited in the study, of which 120 patients were finally included in the analysis, that is 58 patients in stage I (test set) and 62 patients in stage II (validation set). In stage I, 14 (24.1%), patients died during 28 days, and the expression of PD-1 in Tregs (OR:1.037;95%CI:1.003-1.071) and SOFA scores(OR:1.262;95%CI:1.046-1.524) were independent risk factors for 28-day mortality. The ability of Tregs PD-1 in predicting 28-day mortality was validated in stage II (AUC = 0.792).

CONCLUSION

PD-1 overexpression in Tregs was associated with poor outcomes, and PD-1 in Tregs is considered to be a valuable tool for the prediction of prognosis in septic patients using sepsis-3.0 criteria.

Multiparameter flow cytometry analysis of leukocyte markers for diagnosis in preterm neonatal sepsis

PURPOSE

Neonatal sepsis is an important public health concern worldwide due to its immediate lethality and long-term morbidity rates, Clinical evaluation and laboratory analyses are indispensable for diagnosis of neonatal sepsis. However, assessing multiple biomarkers in neonates is difficult due to limited blood availability. The aim is to investigate if the neonatal sepsis in preterm could be identified by multiparameter analysis with flow cytometry.

MATERIALS AND METHODS

The expression of activation-related molecules was evaluated by flow cytometry in newborn with or without risk factors for sepsis.

RESULTS

Our analysis revealed that several markers could be useful for sepsis diagnosis, such as CD45RA, CD45RO, or CD71 on T cells; HLA-DR on NKT or classic monocytes, and TREM-1 on non-classic monocytes or neutrophils. However, ROC analysis shows that the expression of CD45RO on T lymphocytes is the only useful biomarker for diagnosis of neonatal late-onset sepsis. Also, decision tree analyses showed that CD45RO plus CD27 could help differentiate the preterm septic neonates from those with risk factors.

CONCLUSIONS

Our study shows a complementary and practical strategy for biomarker assessment in neonatal sepsis.