High-purity neutrophil isolation from human peripheral blood and saliva for transcriptome analysis

Treponema denticola stimulates Oncostatin M cytokine release and de novo synthesis in neutrophils and macrophages

Oncostatin M (OSM) is a pleiotropic cytokine elevated in a number of inflammatory conditions including periodontal disease. OSM is produced by a variety of immune cells and has diverse functionality such as regulation of metabolic processes, cell differentiation, and the inflammatory response to bacterial pathogens. The oral cavity is under constant immune surveillance including complementary neutrophil and macrophage populations, due to a persistent symbiotic bacterial presence. Periodontal disease is characterized by a dysbiotic bacterial community, with an abundance of Treponema denticola. Despite strong associations with severe periodontal disease, the source and mechanism of the release of OSM have not been defined in the oral cavity. We show that OSM protein is elevated in the gingival epithelium and immune cell infiltrate during periodontal disease. Furthermore, salivary and oral neutrophil OSM is elevated in correlation with the presence of T. denticola. In an air pouch infection model, T. denticola stimulated higher levels of OSM than the oral pathogen Porphorymonas gingivalis, despite differential recruitment of innate immune cells suggesting T. denticola has distinct properties to elevate OSM levels. OSM release and transcription were increased in isolated human blood, oral neutrophils, or macrophages exposed to T. denticola in vitro as measured by ELISA, qPCR, and microscopy. Using transcription, translation, and actin polymerization inhibition, we found that T. denticola stimulates both OSM release through degranulation and de novo synthesis in neutrophils and also OSM release and synthesis in macrophages. Differential induction of OSM by T. denticola may promote clinical periodontal disease.

Blood collection technique, anticoagulants and storing temperature have minor effects on the isolation of polymorphonuclear neutrophils

In the isolation of polymorphonuclear neutrophils (PMNs) the technique and other external factors can have great influence on the quality and quantity of isolated neutrophils. To elucidate the influence of the blood collection technique, anticoagulants and storing temperature on isolated PMNs healthy volunteers provided blood samples with different needles and collection techniques, anticoagulants (EDTA, heparin, citrate) and storing temperatures (4, 22, 37 °C). From each blood sample PMNs were isolated and compared regarding number of PMNs and oxidative burst. The blood collection technique, anticoagulants and storing temperature had minor impact on isolated PMNs. All three tested cannulas and anticoagulants can be used to obtain blood samples for PMN isolation. For storing temperatures 37 °C should be preferred. Regarding time between the PMN isolation and the actual experiments, a time span of maximum 1 h should be targeted.

Cytokine physiognomies of MSCs from varied sources confirm the regenerative commitment post-coculture with activated neutrophils

The interaction of mesenchymal stromal cells (MSCs) with paracrine signals and immunological cells, and their responses and regenerative commitment thereafter, is understudied. In the current investigation, we compared MSCs from the umbilical cord blood (UCB), dental pulp (DP), and liposuction material (LS) on their ability to respond to activated neutrophils. Cytokine profiling (interleukin-1α [IL-1α], IL-2, IL-4, IL-6, IL-8, tumor necrosis factor-α [TNF-α], interferon-γ [IFN-γ], transforming growth factor-β [TGF-β]), cellular proliferation and osteogenic differentiation patterns were assessed. The results showed largely comparable cytokine profiles with higher TNF-α and IFN-γ levels in LSMSCs owing to their mature cellular phenotype. The viability and proliferation between LS/DP/UCB MSCs were comparable in the coculture group, while direct activation of MSCs with lipopolysaccharide (LPS) showed comparable proliferation with significant cell death in UCB MSCs and slightly higher cell death in the other two types of MSC. Furthermore, when MSCs post-neutrophil exposure were induced for osteogenic differentiation, though all the MSCs devoid of the sources differentiated, we observed rapid and significant turnover of DPMSCs positive of osteogenic markers rather than LS and UCB MSCs. We further observed a significant turnover of IL-1α and TGF-β at mRNA and cytokine levels, indicating the commitment of MSCs to differentiate through interacting with immunological cells or bacterial products like neutrophils or LPS, respectively. Taken together, these results suggest that MSCs have more or less similar cytokine responses devoid of their anatomical niche. They readily switch over from the cytokine responsive cell phenotype at the immunological microenvironment to differentiate and regenerate tissue in response to cellular signals.

Extracellular vesicles from human saliva promote hemostasis by delivering coagulant tissue factor to activated platelets

Essentials Human salivary extracellular vesicles (EVs) expose coagulant tissue factor (TF). Salivary EVs expose CD24, a ligand of P-selectin. CD24 and coagulant TF co-localize on salivary EVs. TF+ /CD24+ salivary EVs bind to activated platelets and trigger coagulation.

SUMMARY

Background Extracellular vesicles (EVs) from human saliva expose coagulant tissue factor (TF). Whether such TF-exposing EVs contribute to hemostasis, however, is unknown. Recently, in a mice model, tumor cell-derived EVs were shown to deliver coagulant TF to activated platelets at a site of vascular injury via interaction between P-selectin glycoprotein ligand-1 (PSGL-1) and P-selectin. Objectives We hypothesized that salivary EVs may deliver coagulant TF to activated platelets via interaction with P-selectin. Methods We investigated the presence of two ligands of P-selectin on salivary EVs, PSGL-1 and CD24. Results Salivary EVs expose CD24 but PSGL-1 was not detected. Immune depletion of CD24-exposing EVs completely abolished the TF-dependent coagulant activity of cell-free saliva, showing that coagulant TF and CD24 co-localize on salivary EVs. In a whole blood perfusion model, salivary EVs accumulated at the surface of activated platelets and promoted fibrin generation, which was abolished by an inhibitory antibody against human CD24. Conclusions A subset of EVs in human saliva expose coagulant TF and CD24, a ligand of P-selectin, suggesting that such EVs may facilitate hemostasis at a site of skin injury where the wound is licked in a reflex action.