Rationale: Although the outcome of sepsis benefits from the prompt administration of appropriate antibiotics on correct diagnosis, the assessment of infection in critically ill patients is often a challenge for clinicians. In this setting, simple biomarkers, especially when used in combination, could prove useful. Objectives: To determine the usefulness of combination biomarkers to diagnose sepsis. Methods: Three hundred consecutive patients were enrolled to construct a biologic score that was next validated in an independent prospective cohort of 79 critically ill patients from another center. Measurement and Main Results: Plasma concentrations of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) and procalcitonin (PCT) were assayed, and the expression of the high-affinity immunoglobulin-Fc fragment receptor I (FcγRI) CD64 on neutrophils (polymorphonuclear [PMN] CD64 index) in flow cytometry was measured. A “bioscore” combining these biomarkers was constructed. Serum concentrations of PCT and sTREM-1 and the PMN CD64 index were higher in patients with sepsis compared with all others (P < 0.001 for the three markers). These biomarkers were all independent predictors of infection, the best receiver-operating characteristic curve being obtained for the PMN CD64 index. The performance of the bioscore, better than that of each individual biomarker, was externally confirmed in the validation cohort. Conclusions: This prospective study, including inceptive and validation cohorts of unselected intensive care unit patients, demonstrates the high performance of a bioscore combining the PMN CD64 index together with PCT and sTREM-1 serum levels in diagnosing sepsis in the critically ill patient.

Background: In the bone marrow, hematopietic and mesenchymal stem cells form a unique niche in which the oxygen tension is low. Hypoxia may have a role in maintaining stem cell fate, self renewal and multipotency. However, whereas most studies addressed the effect of transientin vitroexposure of MSC to hypoxia, permanent culture under hypoxia should reflect the better physiological conditions.Results: Morphologic studies, differentiation and transcriptional profiling experiments were performed on MSC cultured in normoxia (21% O₂) versus hypoxia (5% O₂) for up to passage 2. Cells at passage 0 and at passage 2 were compared, and those at passage 0 in hypoxia generated fewer and smaller colonies than in normoxia. In parallel, MSC displayed (>4 fold) inhibition of genes involved in DNA metabolism, cell cycle progression and chromosome cohesion whereas transcripts involved in adhesion and metabolism (CD93, ESAM, VWF, PLVAP, ANGPT2, LEP, TCF1) were stimulated. Compared to normoxic cells, hypoxic cells were morphologically undifferentiated and contained less mitochondrias. After this lag phase, cells at passage 2 in hypoxia outgrew the cells cultured in normoxia and displayed an enhanced expression of genes (4-60 fold) involved in extracellular matrix assembly (SMOC2), neural and muscle development (NOG, GPR56, SNTG2, LAMA) and epithelial development (DMKN). This group described herein for the first time was assigned by the Gene Ontology program to "plasticity".Conclusion: The duration of hypoxemia is a critical parameter in the differentiation capacity of MSC. Even in growth promoting conditions, hypoxia enhanced a genetic program that maintained the cells undifferentiated and multipotent. This condition may better reflect thein vivogene signature of MSC, with potential implications in regenerative medicine.

Apoptotic leukocytes are endowed with immunomodulatory properties that can be used to enhance hematopoietic engraftment and prevent graft-versus-host disease (GvHD). This apoptotic cell-induced tolerogenic effect is mediated by host macrophages and not recipient dendritic cells or donor phagocytes present in the bone marrow graft as evidenced by selective cell depletion and trafficking experiments. Furthermore, apoptotic cell infusion is associated with TGF-β-dependent donor CD4⁺CD25⁺ T-cell expansion. Such cells have a regulatory phenotype (CD62L^high and intracellular CTLA-4⁺), express high levels of forkhead-box transcription factor p3 (Foxp3) mRNA and exert ex vivo suppressive activity through a cell-to-cell contact mechanism. In vivo CD25 depletion after apoptotic cell infusion prevents the apoptotic cell-induced beneficial effects on engraftment and GvHD occurrence. This highlights the role of regulatory T cells in the tolerogenic effect of apoptotic cell infusion. This novel association between apoptosis and regulatory T-cell expansion may also contribute to preventing deleterious autoimmune responses during normal turnover.

Cross-tolerization of T lymphocytes after apoptotic cell uptake by dendritic cells may be involved in self-tolerance maintenance. Furthermore, immunosuppressive properties are attributed to apoptotic cells. This study evaluated the consequences of apoptotic leukocyte administration in a restrictive engraftment model of murine bone marrow (BM) transplantation. Sublethally irradiated recipients received a limited number of allogeneic BM, with or without irradiated apoptotic leukocytes of different origins. No graft-versus-host disease was observed. Whereas only a low proportion of mice receiving BM cells alone engrafted, addition of apoptotic irradiated leukocytes, independently of the origin (donor, recipient, third-party mice, as well as xenogeneic peripheral blood mononuclear cells), significantly enhanced engraftment. Similar results were obtained after infusion of leukocytes rendered apoptotic by UVB irradiation or by anti-Fas monoclonal antibody stimulation, thus confirming the role of apoptotic cells in engraftment facilitation. Overall, these results suggest that apoptotic leukocytes can nonspecifically facilitate allogeneic BM engraftment. Such a simple approach could be of interest in BM transplantation settings involving an important HLA donor/recipient disparity, a T-cell–depleted graft, or reduced conditioning regimen intensity.

The new coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has recently put the world under stress, resulting in a global pandemic. Currently, there are no approved treatments or vaccines, and this severe respiratory illness has cost many lives. Despite the established antimicrobial and immune-boosting potency described for honey, to date there is still a lack of evidence about its potential role amid COVID-19 outbreak. Based on the previously explored antiviral effects and phytochemical components of honey, we review here evidence for its role as a potentially effective natural product against COVID-19. Although some bioactive compounds in honey have shown potential antiviral effects (i.e., methylglyoxal, chrysin, caffeic acid, galangin and hesperidinin) or enhancing antiviral immune responses (i.e., levan and ascorbic acid), the mechanisms of action for these compounds are still ambiguous. To the best of our knowledge, this is the first work exclusively summarizing all these bioactive compounds with their probable mechanisms of action as antiviral agents, specifically against SARS-CoV-2.