Predictive value of peripheral lymphocyte subsets for the disease progression in patients with sepsis

Combining host immune response biomarkers and clinical scores for early prediction of sepsis in infection patients

BACKGROUND

The performance of host immune responses biomarkers and clinical scores was compared to identify infection patient populations at risk of progression to sepsis, ICU admission and mortality.

METHODS

Immune response biomarkers were measured and NEWS, SIRS, and MEWS. Logistic and Cox regression models were employed to evaluate the strength of association.

RESULTS

IL-10 and NEWS had the strongest association with sepsis development, whereas IL-6 and CRP had the strongest association with ICU admission and in-hospital mortality. IL-6 [HR (95%CI) = 2.68 (1.61-4.46)] was associated with 28-day mortality. Patient subgroups with high IL-10 (≥ 5.03 pg/ml) and high NEWS (> 5 points) values had significantly higher rates of sepsis development (88.3% vs 61.1%; p < 0.001), in-hospital mortality (35.0% vs. 16.7%; p < 0.001), 28-day mortality (25.0% vs. 5.6%; p < 0.001), and ICU admission (66.7% vs. 38.9%; p < 0.001).

CONCLUSIONS

Patients exhibiting low severity signs of infection but high IL-10 levels showed an elevated probability of developing sepsis. Combining IL-10 with the NEWS score provides a reliable tool for predicting the progression from infection to sepsis at an early stage. Utilizing IL-6 in the emergency room can help identify patients with low NEWS or SIRS scores.

Causal relationships between immune cells, inflammatory cytokines, and pertussis: Bidirectional 2-sample Mendelian randomization study and mediation analysis

Studies have shown that immune cells play an important role in the occurrence and development of pertussis, but the specific causal relationships are yet to be determined. Additionally, inflammatory cytokines, as regulators of immune responses, may mediate the relationship between immune cells and pertussis, and the specific mechanisms involved require further exploration. This study utilizes data from multiple large-scale genome-wide association studies, covering 731 types of immune cells and 91 types of inflammatory cytokines. The bidirectional 2-sample Mendelian randomization (MR) method is employed, with inverse-variance weighted as the main statistical approach, to assess the causal relationships between immune cells, inflammatory cytokines, and pertussis. Furthermore, a 2-step MR method is used to investigate the mediating role of inflammatory cytokines in the effect of immune cells on pertussis. Our study results indicate that 11 types of immune cells have a protective effect against pertussis, with the strongest protection observed from CD25 on CD28+ CD4+ cells (OR = 0.3533, CI = 0.1636-0.7627, P = .008). Conversely, 19 types of immune cells are positively associated with the risk of pertussis, with the strongest correlation found in CD3- lymphocyte %lymphocyte (OR = 3.6613, CI = 1.5012-8.299, P = .0043). Additionally, 3 inflammatory cytokines - IL-4, IL-18R1, and FGF-21 - show a causal relationship with pertussis. Our mediation MR results indicate that inflammatory cytokines do not act as mediators in the relationship between immune cells and pertussis. This study suggests a causal relationship between immune cells and pertussis, while inflammatory cytokines do not appear to be mediating factors in the pathway from immune cells to pertussis.

The Predictive Value of Absolute Lymphocyte Count and T Cell Subpopulations for Sepsis Prognosis

BACKGROUND

Sepsis causes substantial morbidity and mortality and constitutes a major public health problem. In patients with sepsis, immunosuppression is associated with poor prognosis, and immune monitoring during the early stages has prognostic value. This study aims to explore immunologic parameters associated with sepsis prognosis, potentially identifying patients who may benefit from immunotherapy, improving intensive care survival.

METHODS

A total of 65 patients with sepsis from the Department of Emergency Medicine were divided based on survival at 28 days (47 in the survival group, 18 in the non-survival group). Peripheral blood was collected to measure absolute lymphocyte count and T lymphocyte subpopulations, including the percentage and absolute count of total T cells, CD4+ T, CD8+ T, and NK cells, and the percentages of naïve CD4+ T, central memory CD4+ T, effector CD4+ T, effector memory CD4+ T, naïve CD8+ T, central memory CD8+ T, effector CD8+ T, effector memory CD8+ T, CD4+HLA-DR+ T, and CD8+HLA-DR+ T cells, and Tregs. The differences in these parameters between the two groups were compared and a regression model was constructed to identify possible risk factors for death in patients with sepsis.

RESULTS

The absolute lymphocyte count, absolute T cell count (CD3+, CD4+, and CD8+) and naïve CD4+ T cell percentage were significantly lower in the non-survival group. Conversely, Tregs were higher in patients who did not survive sepsis. In regression analysis, the absolute lymphocyte count and naïve CD4+ T cell percentage remained statistically significant. The receiver operating characteristic curve showed that a model based on the absolute lymphocyte count (435 cells/µL) and naïve CD4+ T cell percentage (20.25%) performed best in predicting sepsis prognosis.

CONCLUSION

Monitoring of absolute lymphocyte count and analysis of T cell subtypes in the early phase of sepsis is predictive of outcome and may help identify those patients who would benefit from immunotherapy, improving survival.

Role of Histiocyte-Derived frHMGB1 as a Facilitator in Noncanonical Pyroptosis of Monocytes/Macrophages in Lethal Sepsis

In this study, we investigated the role of the noncanonical pyroptosis pathway in the progression of lethal sepsis. Our findings emphasize the significance of noncanonical pyroptosis in monocytes/macrophages for the survival of septic mice. We observed that inhibiting pyroptosis alone significantly improved the survival rate of septic mice and that the HMGB1 A box effectively suppressed this noncanonical pyroptosis, thereby enhancing the survival of septic mice. Additionally, our cell in vitro experiments unveiled that frHMGB1, originating from lipopolysaccharide-carrying histiocytes, entered macrophages via RAGE, resulting in the direct activation of caspase 11 and the induction of noncanonical pyroptosis. Notably, A box's competitive binding with lipopolysaccharide impeded its entry into the cell cytosol. These findings reveal potential therapeutic strategies for slowing the progression of lethal sepsis by modulating the noncanonical pyroptosis pathway.

Clinical characteristics and risk factors for mortality in pneumonia-associated acute respiratory distress syndrome patients: a single center retrospective cohort study

Background

Pathogenic diversity may have contributed to the high mortality of pneumonia-associated acute respiratory distress syndrome (p-ARDS). Metagenomics next-generation sequencing (mNGS) serves as a valuable diagnostic tool for early pathogen identification. However, its clinical utility in p-ARDS remains understudied. There are still limited researches on the etiology, clinical characteristics and risk factors for 28-day mortality in p-ARDS patients.

Methods

A single center retrospective cohort study of 75 p-ARDS patients was conducted. Patients were categorized into survival and deceased groups based on their 28-day outcomes. A comprehensive clinical evaluation was conducted, including baseline characteristics, laboratory indicators, outcomes and pathogen identification by mNGS and traditional microbiological testing. We then evaluated the diagnostic value of mNGS and identified clinical characteristics and risk factors for 28-day mortality in p-ARDS.

Result

The overall ICU mortality was 26.67%, and the 28-day mortality was 57.33%, with 32 cases (42.67%) in the survival group, and 43 cases (57.33%) in the deceased group. Patients in the deceased group were older than those in the survival group (68(59,73) years vs. 59(44,67) years, P=0.04). The average lengths of ICU and hospital stay were 9(5,13) days and 14(7,21) days, respectively. The survival group had longer lengths of ICU and hospital stay (ICU: 11(7,17) days and hospital: 17(9,27) days) compared to the deceased group (ICU: 8(4,11) days and hospital: 12(6,19) days) (P<0.05). Survival patients exhibited lower Acute Physiology and Chronic Health Evaluation (APACHE) II score on the 3rd and 7th days, higher lymphocyte counts, higher CD3+ and CD8+ T cell counts compared to deceased patients (P<0.05). Multivariate logistic regression analysis identified age, APACHE II scores on 3rd and 7th days, CD8+ T cell count and length of ICU as independent risk factors for 28-day mortality in p-ARDS patients. mNGS demonstrated a significantly higher overall pathogen detection rate (70/75, 93.33%) compared to the traditional method (50/75, 66.67%, P=0.022). The average turnaround time (TAT) for mNGS was significantly shorter at 1(1,1) day compared to 4(3,5) days for the traditional method (P<0.001).

Conclusion

Metagenome next-generation sequencing can be used as a valuable tool for identifying pathogens in p-ARDS, reducing diagnostic time and improving accuracy. Early application of mNGS alongside traditional methods is recommended for p-ARDS. Furthermore, older age, higher APACHE II scores, lower lymphocyte counts and lymphocyte subset counts were associated with increased mortality in p-ARDS patients, highlighting the importance of timely assessment of immune status and disease severity, especially in elderly.

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.

[The Immune System of the Critically Ill Patient]

Critically ill patients often experience a dysregulated immune response, leading to immune dysfunction. Sepsis, trauma, severe infections, and certain medical conditions can trigger a state of systemic inflammation, known as the cytokine storm. This hyperactive immune response can cause collateral damage to healthy tissues and organs, exacerbating the patient's condition. On the other hand, some critically ill patients may suffer from immune paralysis which can increase the risk of nosocomial infections.Fever is an evolutionary adaptation that evolved as an effective defense mechanism to fight invading pathogens. By raising body temperature, fever enhances the immune response, inhibits pathogen growth, promotes recovery, and aids in the formation of immune memory. Understanding the role of fever in the context of immune defense is crucial for optimizing medical interventions and supporting the body's natural ability to combat infections.Future Directions: Advancements in immunology research and technology hold promise for better understanding the immune system's complexities in critically ill patients. Personalized medicine approaches may be developed to tailor therapies to individual patients based on their immune profile, optimizing treatment outcomes. Based on recent studies prognostic parameters such as lymphocyte count, IL-10 concentration and mHLA-DR expression can be used to stratify the immunological response pattern in septic patients.Conclusion: The immune system's response in critically ill patients is a multifaceted process, involving intricate interactions between various immune cells, cytokines, and organs. Striking the delicate balance between immune activation and suppression remains a significant challenge in clinical practice. Continued research and therapeutic innovations are vital to improve patient outcomes and reduce the burden of critical illness on healthcare systems.

Analysis of mitochondrial function in lymphocytes obtained from COVID-19 patients

OBJECTIVES

There is a significant decline in the lymphocyte subset counts in the peripheral blood of COVID-19 patients. However, the mitochondrial function of lymphocytes obtained from COVID-19 patients has rarely been studied.

METHODS

A case-control study was conducted in 115 COVID-19 patients and 50 healthy controls from December 2022 to February 2023. The extent of lymphocytic mitochondrial damage in these patients using mitochondrial fluorescence staining and flow cytometry. Clinical symptoms were evaluated using the SOFA and APACHE II scores.

RESULTS

The mitochondrial function of lymphocytes was severely impaired in the peripheral blood of COVID-19 patients, compared to healthy controls, and was characterized by an increased single-cell mitochondrial mass (SCMM) and increased percentage of low mitochondrial membrane potential. The increase in the SCMM of T cells was more notable in patients with severe COVID-19 and was positively correlated with the SOFA and APACHE II scores. When the SCMM-CD8 cutoff value was 38.775, the AUC for distinguishing between severe and mild COVID-19 was 0.740, and the sensitivity, specificity, and Youden index were 65.8%, 82.1%, and 0.478, respectively.

CONCLUSION

SCMM-CD8 could act as a diagnostic biomarker of COVID-19 progression. However, this needs to be verified in other multi-center studies with a larger sample size.