Bacterial N-formyl Peptides Reduce PMA- and Escherichia coli-Induced Neutrophil Respiratory Burst in Term Neonates and Adults

Comparative Expression Analysis of Innate Immune Markers and Phagocytic Activity in Peripheral Blood of Dogs with Mammary Tumors

Simple Summary

The presented study aimed to find out the differences between peripheral blood immune cell markers from healthy bitches and bitches with mammary tumors. Due to the fact that the role of canine innate immune cells in cancer remains poorly understood, the markers of innate cells were chosen for this research. Blood samples from female dogs with mammary tumors of epithelial and mesenchymal origin were investigated by flow cytometry. CD5 and CD11b markers of innate immune cells, phagocytic activity, and cellular killing were assessed. The number of CD11b lymphocytes was increased in tumors with epithelial origin. No significant differences were found between the percentages of phagocytic cells. However, the phagocytes of canine patients with tumors of epithelial origin showed increased phagocytosis compared to the control group. In oxidative burst test, a statistically significant difference between the number of reactive oxygen species (ROS) produced was demonstrated only between the group of bitches with epithelial tumors and the control group. These results may suggest that there are subpopulations of innate immune cells that may be involved in anti-tumor immune mechanisms and have a potential to be supportive diagnostic markers in canine mammary tumors.

Abstract

Canine innate immune system role in cancer prevention and progression remains poorly understood. It has been revealed that innate immune cells could play a dual role in cancer immunology promoting or inhibiting tumor development and growth. Current immunotherapies target mainly the adaptive anti-tumor response and that may be a reason why they remain ineffective in a majority of patients. It is important to acquire detailed knowledge about innate immune mechanisms to broaden the diagnostic and therapeutic options and employ innate immune cells in anti-cancer therapies. In the present study, 21 female dogs of different breeds and types of spontaneous mammary tumors were investigated. The study aimed to find simple and cheap markers that can be used for preliminary diagnosis, prior to the surgical resection of the tumor. The differences in innate immune cell quantity and function were investigated between female dogs with malignant mammary tumors of epithelial and mesenchymal origin. Flow cytometry was used to evaluate the percentages of CD5+ lymphocytes including CD5^low lymphocytes, CD11b integrin expression on leukocytes, phagocytosis, and oxidative burst. The number of CD11b lymphocytes was increased in tumors with epithelial origin compared to the control group. No significant differences were found between the percentages of phagocytic cells neither for granulocytes nor for monocytes. However, the phagocytes of canine patients with tumors of epithelial origin showed increased phagocytosis compared to the control group. The percentages of granulocytes that produced reactive oxygen species (ROS) in response to E.coli and PMA were not altered in patients with malignant tumors compared to control. A statistically significant difference between the number of ROS produced by the single granulocyte was demonstrated only between the group of bitches with epithelial tumors and the control group in case of E. coli stimulation. The obtained results suggest that some innate immune cells may be involved in anti-tumor immune mechanisms and have the potential to be supportive diagnostic markers in canine mammary tumors.

Microbiota Signals during the Neonatal Period Forge Life-Long Immune Responses

The microbiota regulates immunological development during early human life, with long-term effects on health and disease. Microbial products include short-chain fatty acids (SCFAs), formyl peptides (FPs), polysaccharide A (PSA), polyamines (PAs), sphingolipids (SLPs) and aryl hydrocarbon receptor (AhR) ligands. Anti-inflammatory SCFAs are produced by Actinobacteria, Bacteroidetes, Firmicutes, Spirochaetes and Verrucomicrobia by undigested-carbohydrate fermentation. Thus, fiber amount and type determine their occurrence. FPs bind receptors from the pattern recognition family, those from commensal bacteria induce a different response than those from pathogens. PSA is a capsular polysaccharide from B. fragilis stimulating immunoregulatory protein expression, promoting IL-2, STAT1 and STAT4 gene expression, affecting cytokine production and response modulation. PAs interact with neonatal immunity, contribute to gut maturation, modulate the gut–brain axis and regulate host immunity. SLPs are composed of a sphingoid attached to a fatty acid. Prokaryotic SLPs are mostly found in anaerobes. SLPs are involved in proliferation, apoptosis and immune regulation as signaling molecules. The AhR is a transcription factor regulating development, reproduction and metabolism. AhR binds many ligands due to its promiscuous binding site. It participates in immune tolerance, involving lymphocytes and antigen-presenting cells during early development in exposed humans.

Measuring the Asian seabass (Lates calcarifer) neutrophil respiratory burst activity by the dihydrorhodamine-123 reduction flow cytometry assay in whole blood

The neutrophil oxidative respiratory burst response is a key component of the innate immune system responsible for killing microbial pathogens. Since fish rely on the innate immune system for health, monitoring the respiratory burst activity may be an effective means of gauging fish health status. Here we report that the respiratory burst of Asian seabass neutrophils can be measured in whole blood by the dihydrorhodamine (DHR)-123 reduction assay and flow cytometry. Neutrophils responded to phorbol myristate acetate (PMA) in a concentration dependent manner with significant respiratory burst activity at 100-1000 nM. Other known neutrophil agonists, such as bacterial lipopolysaccharide, tumor necrosis factor, the tripeptide f-met-leu-phe and zymosan, did not induce a significant DHR reduction. Thus, the findings enable us to propose that the DHR-123 flow cytometry whole blood assay, incorporating PMA as a stimulator, would not only facilitate future studies into fish blood neutrophil research but provides a simple, rapid and reliable assay for gauging fish natural immunity status and health.

[Neutrophil respiratory burst and the state of hemostasis in patients with ischemic and hemorrhagic stroke]

AIM

To study the relationship between the state of the respiratory burst of neutrophils and the indices of hemostasis in patients with ischemic (IS) and hemorrhagic (HS) strokes.

MATERIAL AND METHODS

Thirty-three patients with IS and 31 patients with HS were examined in the first 24 hours after an acute cerebrovascular accident (ACA). The diagnosis of ASA was confirmed by neuroimaging methods: computed tomography and magnetic resonance imaging. The determination of the respiratory burst state of blood neutrophils was carried out using chemiluminescence analysis. Indicators of vascular-platelet and coagulation hemostasis were determined in all patients.

RESULTS AND CONCLUSION

There were changes in the kinetics and activity of neutrophil respiratory burst in stroke patients. Patients with HS had higher (compared to those of patients with IS) level of spontaneous and induced synthesis of secondary ROS but with a decrease in metabolic resources for their synthesis. Activation of spontaneous and ADP-induced platelet aggregation was detected only in HS. Patients with HS had a higher level of fibrinolytic activity as compared to the patients with IS. There were positive correlations between the kinetic parameters of blood coagulation and the synthesis of primary ROS by neutrophils in patients with HS, whereas the intensity of all ROS synthesis negatively correlated with activated partial thromboplastin time. Therefore, in patients with HS the synergistic relationship between the respiratory burst of neutrophils (pro-inflammatory activity) and coagulation hemostasis was more pronounced compared to patients with IS.

Potent NETosis inducers do not show synergistic effects in vitro

Introduction

NETosis is a process whereby neutrophils release chromatin into the surrounding extracellular matrix to form neutrophil extracellular traps (NETs). Under physiological conditions NETosis can be initiated by a variety of stimuli, including immune complexes, complement activation products, and a milieu of proinflammatory cytokines. Because overproduction of NETs is often related to the promotion or aggravation of autoimmune responses, we decided to assess how simultaneous activation of NETosis by different stimuli affects NET production.

Material and methods

NET formation was initiated by using combinations of three different NETosis inducers: phorbol myristate acetate (PMA), N-formylmethionyl-leucyl-phenylalanine (fMLP) and calcium ionophore (CaI). We measured fluorometry in real time, while microscopic visualisation served as an additional control for NET release. In total, 30 subjects free from infections or chronic diseases were enrolled in this study.

Results

We were able to demonstrate that in all cases NETosis induced by a combination of two stimuli resulted in diminished NETs production when compared to PMA and CaI single stimulations (p ≤ 0.001). The only cases in which double stimulation showed similar results to single stimulation were when we compared fMLP + CaI stimulation with fMLP single stimulation. Furthermore, when neutrophils were exposed to all three stimuli NETosis was almost entirely inhibited, compared to any single stimulation (p ≤ 0.001).

Conclusions

Our results show that simultaneous stimulation of neutrophils by different NETosis-inducing agents results in diminished formation of NETs compared to a single stimulation. This indicates that cells may possess an internal regulatory mechanism that prevents overgeneration of NETs among healthy people.