Relationship between glucocorticoids and viral load during the Omicron wave in mainland China.

BACKGROUND: Coronavirus disease 19 (COVID-19) is a major public health problem that cannot be ignored. As a widely used drug in the treatment of COVID-19, whether glucocorticoids may accelerate the clearance of COVID-19 is still not clear, and the glucocorticoids may improve the prognosis of patients is also controversial. Therefore, to explore the relationship between COVID-19 viral load and the use of glucocorticoids we designed this study. METHODS: Patients with COVID-19 infection who were admitted to the emergency department of Peking Union Medical College Hospital from the end of 2022 to early 2023 were enrolled in this study. Characteristics of baseline, clinical and laboratory evaluation especially immunological indicator and daily viral load were carefully collected. Kolmogorov-Smirnov test, Student's t test, Mann-Whitney U test and proportional-hazards model (Cox model) were chosen as appropriate for comparison of variables. RESULTS: By comparing the daily COVID-19 viral load and prognosis of patients with and without glucocorticoid therapy, we found that glucocorticoids did not statistically enhance the clearance or replication of COVID-19, nor did it change the 28-days and in-hospital mortality. However, glucocorticoid therapy may be a favorable factor for COVID-19 negative conversion in Cox model. The inflammatory factors in patients with glucocorticoid therapy were significantly decreased. CONCLUSIONS: We believe that the real effect of glucocorticoids may be to improve the destruction of host immune system caused by inflammatory storm through host immune regulation and then achieve the improvement of clinical symptoms.

mTOR pathway mediates endoplasmic reticulum stress-induced CD4+ T cell apoptosis in septic mice.

Endoplasmic reticulum stress (ERS) has been well documented to participate in the pathophysiological processes of apoptosis in many diseases. Inhibition of ERS ameliorates pathological organ injury. However, the upstream signaling pathways and molecular regulatory mechanisms of which are still unknown. mTOR, an evolutionarily conserved protein kinase, is a key regulator of apoptosis. Hence, in this study, a classical cecal ligation and puncture (CLP) sepsis model was constructed by using the T cell-specific knockout mTOR and TSC1 (Tuberous Sclerosis Complex, the inhibitor of mTOR signaling pathway) mice to explore the underlying signaling pathway and molecular mechanism of host immune imbalance caused by apoptosis in sepsis. We found that mTOR may modulate septic T cell apoptosis by regulating Akt-IRE1-JNK pathway. To further clarify the possible mechanism, the specific inhibitors of PI3K-Akt and IRE1-JNK were used to intervene in mice before/after CLP, respectively. By analyzing the proteins of mTOR-ERS signaling pathway and the expression of apoptosis-related proteins and genes, we found that mTOR mediated the ER stress induced CD4+ T cell apoptosis in Septic mice by negatively regulating the Akt-IRE1-JNK-Caspase 3 signaling cascades. These results indicate that mTOR-Akt-IRE1α-JNK signaling pathway mediated the Endoplasmic reticulum stress induced CD4+ T cell apoptosis in Septic mice.

mTOR deletion ameliorates CD4 + T cell apoptosis during sepsis by improving autophagosome-lysosome fusion.

Autophagy dysfunction contributes to CD4 + T cell apoptosis during sepsis leading to impairment of adaptive immunity. However, the underlying mechanism is unclear. The mammalian target of rapamycin (mTOR) pathway modulates CD4 + T cell survival during sepsis through mechanisms that are not fully understood. We developed a mouse model of sepsis through cecal ligation and puncture (CLP) to investigate dynamic changes in autophagy in CD4 + T cells. We used T cell specific-mTOR/tuberous sclerosis complex 1 (TSC1)-knockout mice to explore the roles of the mTOR pathway in modulating autophagy during sepsis. We observed reduced fusion of autophagosomes with lysosomes in the CD4 + T cells of CLP mice, which may represent a characteristic feature of autophagy dysfunction. Deletion of mTOR relieved autophagosome-lysosome fusion dysfunction and ameliorated apoptosis of CD4 + T cells in CLP mice, but this rescued phenotype was abolished by treatment with bafilomycin A1, a specific A-L fusion inhibitor. We further explored the underlying molecular mechanism and found that phosphorylation levels of transcription factor EB were significant higher in CLP mice and that expression of A-L fusion protein SNAREs were restricted, both of which were ameliorated by mTOR deletion. Taken together, these results suggest that the mTOR pathway plays a critical role in regulation of CD4 + T-cell apoptosis during sepsis, partly through regulation of A-L fusion-related protein transcription.

T-lymphocyte subtyping: an early warning and a potential prognostic indicator of active cytomegalovirus infection in patients with sepsis.

Cytomegalovirus (CMV) infection is very common in patients suffering from sepsis and may cause poor prognosis. To explore the relationship between immune status of patients with sepsis and CMV infection, we assessed T lymphocyte subtyping and other commonly used clinical parameters in patients with sepsis upon admission to the intensive care unit (ICU) and evaluated their potential impact on diagnosis and outcomes of active CMV infection. In our study, 82 of 599 patients with sepsis were diagnosed with active CMV infection. The 28-day mortality was higher in active CMV-infected than nonactive CMV-infected patients (20.7% versus 9.9%); 51of 82 active CMV-infected patients with sepsis were assessed to have CMV-DNA-negative conversion, while 31 were persistently positive for CMV DNA. Higher CD8+ CD28+ T-cell counts at presentation were associated with CMV-DNA-negative conversion and lower 28-day mortality. The CMV-DNA-negative conversion and 28-day mortality of active CMV-infected patients with sepsis could be predicted using cutoff values of 151 (74.5% sensitivity and 87.1% specificity) and 64.5 (52.9% sensitivity and 92.3% specificity) CD8+ CD28+ T cells mL-1 at ICU admission, respectively. Higher CD8+ CD28+ T-cell count was significantly associated with active CMV infection, higher CMV-DNA-negative conversion and lower 28-day mortality, which may be a potential marker for early warning of active CMV infection and outcome prediction.

Erratum: CD8+ T cell survival in lethal fungal sepsis was ameliorated by T-cell-specific mTOR deletion: Erratum.

[This corrects the article DOI: 10.7150/ijms.55592.].

mTOR Modulates the Endoplasmic Reticulum Stress-Induced CD4+ T Cell Apoptosis Mediated by ROS in Septic Immunosuppression.

Introduction: When sepsis attacks the body, the excessive reactive oxygen species (ROS) production can result to endoplasmic reticulum stress (ERS) and eventually cause lymphocyte apoptosis. The mammalian target of rapamycin (mTOR) is essential for regulating lymphocyte apoptosis; we hypothesized that it mediates CD4+ T cell apoptosis during ROS-related ERS. Method: We, respectively, used ROS and ERS blockers to intervene septic mice and then detected ERS protein expression levels to verify the relationship between them. Additionally, we constructed T cell-specific mTOR and TSC1 gene knockout mice to determine the role of mTOR in ROS-mediated, ERS-induced CD4+ T cell apoptosis. Results: Blocking ROS significantly suppressed the CD4+ T cell apoptosis associated with the reduction in ERS, as revealed by lower levels of GRP78 and CHOP. ERS rapidly induced mTOR activation, leading to the induction of CD4+ T cell apoptosis. However, mTOR knockout mice displayed reduced expression of apoptotic proteins and less ER vesiculation and expansion than what was observed in the wild-type sepsis controls. Conclusion: By working to alleviate ROS-mediated, ERS-induced CD4+ T cell apoptosis, the mTOR pathway is vital for CD4+ T cell survival in sepsis mouse model.

CD8+ T cell survival in lethal fungal sepsis was ameliorated by T-cell-specific mTOR deletion.

Lethal fungal sepsis causes high morbidity and mortality in intensive care patients. Fungal infections have an immunological basis, and it has been shown in recent studies that decreased CD8+ T-cell count in fungal infections is related to prognosis, while the underlying mechanism is still unclear. Here, a lethal fungal sepsis model induced by candidemia was created and we found a decreased CD8+ T-cell count and exaggerated apoptosis. Simultaneously, expression of light chain (LC)3B in CD8+ T cells increased, along with increased autophagosomes and accumulation of p62 in infected mice. We regulated the activity of the mammalian target of rapamycin (mTOR) pathway using T-cell-specific mTOR/ TSC1 deletion mice. We observed increased number of autophagosomes and expression of LC3B in CD8+T cells after T-cell-specific mTOR knockout, while accumulation of p62 was not ameliorated, and there was no increase in the number of autolysosomes. Apoptosis rate and expression of BIM, a pro-apoptotic gene, decreased in CD8+ T cells in mTOR-deletion mice but increased in TSC1-deletion mice. Our results showed increased CD8+ T-cell death in spleen of lethal fungal sepsis mice, and decreased expression of mTOR ameliorated CD8+ T-cell survival. mTOR may be a possible target to reverse CD8+ T-cell immune dysfunction in lethal fungal sepsis.

Depletion of mTOR ameliorates CD4+ T cell pyroptosis by promoting autophagy activity in septic mice.

A reduction in the number of CD4+ T cells is a central part of the immunosuppression phase of sepsis and leads to impaired immune defense ability and increased mortality. Pyroptosis, a newly discovered programmed cell death, was confirmed to be an important mechanism of lymphocytopenia in a lot of human diseases and is under the regulation of autophagy. The mammalian target of rapamycin (mTOR) pathway is closely related to CD4+ T-cell survival. Whether the mTOR pathway influences CD4+ T cell pyroptosis by regulating autophagy remains unknown. In this study, a septic mouse model was developed using cecal ligation and puncture (CLP) to explore the degree of pyroptosis and autophagy of CD4+ T cells. T-cell-specific mTOR/TSC1-knockout mice were used to investigate the role of mTOR pathway in the regulation of CD4+ T cell pyroptosis. Bafilomycin, a specific autophagy inhibitor, was used to verify the regulatory effect of autophagy on pyroptosis in septic mice. We observed aggravated pyroptosis in CD4+ T cells in CLP mice accompanied by impaired autophagy activity and an overactivated mTOR signaling pathway. Depletion of mTOR relieved autophagy deficiency and reduced the proportion of pyroptotic CD4+ T cells. In T-cell-specific mTOR-knockout mice treated with bafilomycin, the protective effect of mTOR depletion vanished. This indicated that autophagy negatively regulates CD4+ T cell pyroptosis, which is under the control of the mTOR pathway. Taken together, our findings emphasize the importance of pyroptosis in sepsis-induced lymphopenia and reveal the regulatory effects of the mTOR pathway and the role of autophagy in this regulation.

Impact of mTOR signaling pathway on CD8+ T cell immunity through Eomesodermin in response to invasive candidiasis.

BACKGROUND: We investigated the effect of the mammalian target of rapamycin (mTOR) pathway on CD8+ T cell immunity through Eomesodermin (Eomes) in intensive care unit (ICU) patients with invasive candidiasis (IC) and in a mouse model. METHODS: We evaluated quantitative changes in parameters of the mTOR/phosphorylated ribosomal S6 kinase (pS6K) pathway and immune system at the onset of infection in ICU patients. The study was registered on 28 February 2017 at chictr.org.cn (ChiCTR-ROC-17010750). We also used a mouse model of Candida infection and constructed T-cell-specific mTOR and T-cell-specific tuberous sclerosis complex (TSC) 1 conditional knockout mice to elucidate the molecular mechanisms. RESULTS: We enrolled 88 patients, including 8 with IC. The IC group had lower CD8+ T cell counts, higher serum levels of mTOR, pS6K, Eomes and interleukin (IL)-6. The mouse model with IC showed results consistent in the clinical study. The CD8+ T cell immune response to IC seemed to be weakened in TSC1 knockout mice compared with wild-type IC mice, demonstrating that mTOR activation resulted in the impaired CD8+ T cell immunity in IC. CONCLUSIONS: In IC, the mTOR activation may play a vital role in impaired CD8+ T cell immunity through enhancing expression of Eomes. The study was registered on 28 February 2017 at chictr.org.cn (identifier ChiCTR-ROC-17010750).

Early Alterations of Lymphocyte Subsets in Acute Respiratory Distress Syndrome Caused by Acinetobacter baumannii Pneumonia: A Prospective Observational Study.

Background: To prospectively observe the early alterations of lymphocyte subsets in ARDS caused by Acinetobacter baumannii. Methods: ARDS patients admitted to our ICU between January 1, 2017 and May 30, 2020 were selected. We enrolled all the pulmonary ARDS caused by Acinetobacter baumannii pneumonia who required mechanical ventilation or vasopressors. All the available clinical data, follow up information and lymphocyte subsets were recorded. Results: Eighty-seven of all the 576 ARDS patients were enrolled. The 28-day mortality of the enrolled patients was 20.7% (18/87). The T lymphocyte count (452 vs. 729 cells/ul, P = 0.004), especially the CD8+ T lymphocyte count (104 vs. 253 cells/ul, P = 0.002) was significantly lower in non-survivors, as were counts of the activated T cell subsets (CD8+CD28+ and CD8+CD38+). The CD8+ T cell count was an independent risk factor for 28-day mortality, and a cutoff value of 123 cells/ul was a good indicator to predict the prognosis of ARDS caused by Acinetobacter baumannii pneumonia, with sensitivity of 74.6% and specificity of 83.3% (AUC 0.812, P < 0.0001). Conclusions: Lower CD8+ T cell count was associated with higher severity and early mortality in ARDS patients caused by Acinetobacter baumannii pneumonia, which could be valuable for outcome prediction.

T-Bet Expression Mediated by the mTOR Pathway Influences CD4+ T Cell Count in Mice With Lethal Candida Sepsis.

The sustained high morbidity and mortality of Candida sepsis are mainly caused by compromise of host immunity. Clinically, it is often manifested as a significant decrease in CD4+ T cell count, although the mechanism is unclear. We established a lethal mice Candida sepsis model and used Murine Sepsis Score to group mice with different disease severity to establish the influence of T-bet expression on CD4+ T cell count in Candida sepsis. We found that CD4+ T cell count decreased in Candida-infected compared to uninfected mice, and the degree of decrease increased with aggravation of sepsis. Expression of T-bet similarly decreased with worsening of sepsis, but it was significantly enhanced in candidiasis in comparison of naïve state. To clarify its possible mechanism, we measured the activity of mammalian target of rapamycin (mTOR), which is a key regulator of T-bet expression. The mTOR pathway was activated after infection and its activity increased with progression of sepsis. We used mice with T-cell-specific knockout of mTOR or tuberous sclerosis complex (TSC)1 to further inhibit or strengthen the mTOR signaling pathway. We found that mTOR deletion mice had a higher CD4+ T cell count by regulating T-bet expression, and the result in TSC1 deletion mice was reversed. These results demonstrate that T-bet expression mediated by the mTOR pathway influences the CD4+ T cell count in mice with Candida sepsis.

Evaluation of the updated "Candida score" with Sepsis 3.0 criteria in critically ill patients.

BACKGROUND: The Candida score proposed in 2009 was calculated on the definition of "severe sepsis", which was removed in the Sepsis 3.0 definition. This study investigated the clinical relevance of Candida score with the updated Sepsis 3.0 definition (CS-3.0) instead of severe sepsis (CS-2009) in the new admitted critically ill patients. METHODS: We performed a retrospective analysis on a single center public database. All patients with ICU stay ≥72 hours were included in this study. The Candida score was calculated based on the data collected on ICU admission. The incidence of invasive candidiasis was determined and its relationship with the CS-2009 and CS-3.0 was studied. RESULTS: A total of 17,666 patients were identified after screening 58,976 hospital admissions, and 436 cases (2.5%) were diagnosed with invasive candidiasis. In the infection group, the number of patients who met the Sepsis 3.0 criteria was greater than the number of patients with severe sepsis (81.2% vs. 78.4%, P<0.005). The area under curve of the CS-2009 was 0.789 (95% CI: 0.765-0.813) and the CS-3.0 was 0.804 (95% CI: 0.782-0.827). CONCLUSIONS: Our study confirmed the clinical relevance and comparative superiority of the updated Candida score model, using the Sepsis 3.0 definition, compared with the classic sepsis/severe sepsis model, in assessment of critically ill patients. Considering the clinical importance of organ dysfunction in ICI, the Sepsis 3.0 should be used as the basis for prediction of invasive candidiasis.

Lymphocyte and NK Cell Counts Can Predict Sepsis-Associated Delirium in Elderly Patients.

Background: Sepsis-associated delirium (SAD) is prevalent in elderly patients and is recognized as brain dysfunction associated with increased inflammatory response in the central nervous system during sepsis. Neuroinflammation was demonstrated to be part of its mechanism and we aimed to validate the role of immunity imbalance in a combined retrospective and prospective cohort study. Methods: We performed a retrospective study analyzing the association between SAD and lymphocyte counts in the peripheral blood, alongside a prospective trial evaluating the quantitative changes in lymphocyte subsets and their predictive value for early diagnosis of SAD. Results: In the retrospective study, among 1,010 enrolled adult patients (age ≥65 years), 297 patients were diagnosed with delirium during intensive care unit (ICU) stay and lymphocyte counts at ICU admission in the SAD group were significantly higher than in non-delirious counterparts (1.09 ± 0.32 vs. 0.82 ± 0.24, respectively, p = 0.001). In the prospective study, lymphocyte counts [0.83 (0.56, 1.15) vs. 0.72 (0.40, 1.06) × 109/L, p = 0.020] and natural killer (NK) cell counts [96 (68, 118) vs. 56 (26, 92) cells/µl, p = 0.024] were significantly higher in the SAD group. The area under the curve value of NK cell count was 0.895 [95% confidence interval (CI): 0.857, 0.933] and of lymphocyte count was 0.728 (95% CI: 0.662, 0.795). An NK cell count cut-off value of 87 cells/ml in septic patients at ICU admission was predictive of delirium with a sensitivity of 80.2% and specificity of 80.8%. Conclusions: We found that lymphocyte and NK cell counts were significantly higher in senior patients with SAD and that NK cell count may be valuable for the prediction of SAD within elderly patient cohorts.

Lymphocyte subset counts as diagnostic and prognostic markers for carbapenem-resistant Enterobacteriaceae (CRE) infection in critically ill patients.

OBJECTIVES: This study investigated the use of lymphocyte subset counts as diagnostic and prognostic markers for carbapenem-resistant Enterobacteriaceae (CRE) infection. METHODS: We assessed the lymphocyte subset populations and other clinical parameters of septic patients upon intensive care unit (ICU) admission, and evaluated their potential impact on CRE infection diagnosis and outcome. RESULTS: Among 373 septic patients, 51 were diagnosed with CRE infection. The 28-day mortality was significantly higher in CRE than non-CRE patients (35.3% vs 14.9%). The T lymphocyte count and CD4+CD28+ T cell count were both independent risk factors for CRE infection, with the latter had the best diagnostic ability (AUC: 0.908; p < 0.0001). Lower CD4+CD28+ T cell counts were associated with higher likelihoods of CRE infection. The CRE incidence and 28-day mortality of CRE-infected patients could be predicted using cutoff values of 242 (sensitivity: 83.9%; specificity: 87.5%) and 58.5 (sensitivity: 100%; specificity: 61.1%) CD4+CD28+ T cells/µl at ICU admission, respectively. CONCLUSIONS: Septic patients with CRE infection had higher 28-day mortality. Given that the CD4+CD28+ T cell count was significantly lower in CRE than non-CRE septic patients and a lower cell count was significantly associated with higher 28-day mortality, CD4+CD28+ T cell counts may be useful markers for early diagnosis of CRE infection and outcome prediction.

T-cell-specific mTOR deletion in mice ameliorated CD4+ T-cell survival in lethal sepsis induced by severe invasive candidiasis.

The mammalian target of rapamycin (mTOR) pathway can mediate T-cell survival; however, the role of this pathway in T-cell survival during fungal sepsis is unclear. Here, we investigated the role of the mTOR pathway in CD4+ T-cell survival in a mouse model of rapidly progressive lethal sepsis induced by severe invasive candidiasis and explored the possible mechanism. The decrease in CD4+ T-cell survival following fungal sepsis was ameliorated in mice with a T-cell-specific mTOR deletion, whereas it was exacerbated in mice with a T-cell-specific tuberous sclerosis complex (TSC)1 deletion. To explore the mechanism further, we measured expression of autophagy proteins light chain 3B and p62/sequestosome 1 in CD4+ T cells. Both proteins were increased in T-cell-specific mTOR knockout mice but lower in T-cell-specific TSC1 knockout mice. Transmission electron microscopy revealed that T-cell-specific mTOR knockout mice had more autophagosomes than wild-type mice following fungal sepsis. CD4+ T-cell mTOR knockout decreased CD4+ T-cell apoptosis in fungal sepsis. Most notably, the T-cell-specific mTOR deletion mice had an increased survival rate after fungal sepsis. These results suggest that the mTOR pathway plays a vital role in CD4+ T-cell survival during fungal sepsis, partly through the autophagy-apoptosis pathway.