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.

Banana Lectin from Musa paradisiaca Is Mitogenic for Cow and Pig PBMC via IL-2 Pathway and ELF1

The aim of the study was to gain deeper insights in the potential of polyclonal stimulation of PBMC with banana lectin (BanLec) from Musa paradisiaca. BanLec induced a marked proliferative response in cow and pig PBMC, but was strongest in pigs, where it induced an even higher proliferation rate than Concanavalin A. Molecular processes associated with respective responses in porcine PBMC were examined with differential proteome analyses. Discovery proteomic experiments was applied to BanLec stimulated PBMC and cellular and secretome responses were analyzed with label free LC-MS/MS. In PBMC, 3955 proteins were identified. After polyclonal stimulation with BanLec, 459 proteins showed significantly changed abundance in PBMC. In respective PBMC secretomes, 2867 proteins were identified with 231 differentially expressed candidates as reaction to BanLec stimulation. The transcription factor “E74 like ETS transcription factor 1 (ELF1)” was solely enriched in BanLec stimulated PBMC. BanLec induced secretion of several immune regulators, amongst them positive regulators of activated T cell proliferation and Jak-STAT signaling pathway. Top changed immune proteins were CD226, CD27, IFNG, IL18, IL2, CXCL10, LAT, ICOS, IL2RA, LAG3, and CD300C. BanLec stimulates PBMC of cows and pigs polyclonally and induces IL2 pathway and further proinflammatory cytokines. Proteomics data are available via ProteomeXchange with identifier PXD027505.

PRMT5 promotes symmetric dimethylation of RNA processing proteins and modulates activated T cell alternative splicing and Ca2+/NFAT signaling

Protein Arginine Methyltransferase (PRMT) 5 is the major type 2 methyltransferase catalyzing symmetric dimethylation (SDM) of arginine. PRMT5 inhibition or deletion in CD4 Th cells reduces TcR engagement-induced IL-2 production and Th cell expansion and confers protection against experimental autoimmune encephalomyelitis (EAE), the animal model of Multiple Sclerosis. However, the mechanisms by which PRMT5 modulates T helper (Th) cell proliferation are still not completely understood and neither are the methylation targets in T cells. In this manuscript, we uncover the role of PRMT5 on alternative splicing (AS) in activated T cells and identify several targets of PRMT5 SDM involved in splicing. In addition, we find a possible link between PRMT5 mediated AS of Trpm4 (Transient Receptor Potential Cation Channel Subfamily M Member 4) and TcR/NFAT signaling/IL-2 production. This understanding may guide development of drugs targeting these processes to benefit patients with T cell-mediated diseases.

Orai1 Mediated Calcium Influx Improves Sepsis-induced T Lymphocyte Immunosuppression and Acute Organ Dysfunction

Sepsis-triggered immune paralysis, particularly CD4+ T-cell dysfunction, increases susceptibility to infections. Ca2+ signals arising from store-operated calcium entry (SOCE) in T lymphocytes are critical mediators to infection, inflammation, and autoimmunity. Orai1 is a major component of SOCE. The role of Orai1 and SOCE in sepsis-induced immunosuppression remain to be elucidated. In this study, we first identified the immunosuppression of splenic CD4+ T cells and CD4+CD25+Treg cell/T helper 17 (Th17) cell imbalance in septic mice. Following this, we found that Ca2+-calcineurin-calcineurin-nuclear factor of activated T cell (NFAT) signaling pathways as well as SOCE were inhibited in septic mice. Further, Upregulation of Orai1 not only can improve immune function of T cell in sepsis but also reduce the mortality and organ damage in septic mice. Lastly, Overexpression of Orai1 can partially recovery of SOCE in sepsis. These data suggest that Orai1 mediated calcium influx can improve sepsis-induced T lymphocyte immunosuppression and acute organ dysfunction.

A procedure for in vitro evaluation of the immunosuppressive effect of mouse mesenchymal stem cells on activated T cell proliferation

Background Mesenchymal stem/stromal cells (MSC) represent adult cells with multipotent capacity. Besides their capacity to differentiate into multiple lineages in vitro and in vivo, increasing evidence points towards the immunomodulatory capacity of these cells, as an important feature for their therapeutic power. Although not included in the minimal criteria established by the International Society for Cellular Therapy as a defining MSC attribute, demonstration of the immunomodulatory capacity of MSC can be useful for the characterization of these cells before being considered MSC. Methods Here we present a simple and reliable protocol by which the immunosuppressive effect of mouse bone marrow-derived MSC can be evaluated in vitro. It is based on the measuring of the proliferation of activated T cells cultured in direct contact with irradiated MSC. Results Our results showed that mouse MSC have a dose-dependent inhibitory effect on activated T cell proliferation, which can be quantified as a percentage of maximum proliferation. Our data shows that batch-to-batch variability can be determined within one or multiple experiments, by extracting the area under curve of T cell proliferation plotted against the absolute number of MSC in co-culture. Conclusions The validation of the immunosupressive capacity of MSC could be added to the characterization of the cells before being used in various MSC-based approaches to treat immunological diseases. Our results showed that mouse MSC have a dose-dependent inhibitory effect on activated T cell proliferation. The immunosuppressive properties of MSC vary between batches, but not between different passages of the same batch.