Neutrophil programming dynamics and its disease relevance

DNase I rescues goat sperm entrapped by neutrophil extracellular traps

Artificial insemination has been a predominant technique employed in goat husbandry for breeding purposes. Subsequent to artificial insemination, sperm can elicit inflammation in the reproductive tract, resulting in substantial the accumulation of neutrophils. Recognized as foreign entities, sperm may become entrapped within neutrophil extracellular traps (NETs) released by neutrophils, thereby exploiting their properties of pathogen elimination. Deoxyribonuclease I (DNase I), which is known for disintegrating NETs and causing loss of function, has been utilized to ameliorate liver and brain damage resulting from NETs, as well as to enhance sperm quality. This study investigated the mechanism of sperm-induced NETs and further explored the impact of DNase I on NETs. Sperm quality was evaluated using optical microscopy, while the structure of NETs was observed through immunofluorescence staining. The formation mechanism of NETs was examined using inhibitors and PicoGreen. The findings revealed that sperm induced the formation of NETs, a process regulated by glycolysis, NADPH oxidase, ERK1/2, and p38 signaling pathways. The composition of NETs encompassed DNA, citrullinated histone H3 (citH3), and elastase (NE). DNase I protects sperm by degrading NETs, thereby concurrently preserving the integrity of plasma membrane and motility of sperm. In summary, the release of sperm-induced NETs leads to its damage, but this detrimental effect is counteracted by DNase I through degradation of NETs. These observations provide novel insights into reproductive immunity in goats.

Enhanced Neutrophil Immune Homeostasis Due to Deletion of PHLPP

Neutrophils are known to adopt dynamic and distinct functional phenotypes involved in the modulation of inflammation and immune homeostasis. However, inter-cellular signaling mechanisms that govern neutrophil polarization dynamics are not well understood. Employing a novel model of PHLPP deficient mice, we examined how neutrophils deficient in PHLPP may uniquely modulate immune defense and the host response during acute colitis. We found that PHLPP^-/- mice were protected from dextran sodium sulfate (DSS)-induced septic colitis characterized by minimal body weight-loss, alleviated colon tissue destruction and reduced clinical symptoms. PHLPP^-/- neutrophils have enhanced immune homeostasis as compared to WT neutrophils, reflected in enhanced migratory capacity toward chemoattractants, and reduced expression of inflammatory mediators due to elevated phosphorylation of AKT, STAT1, and ERK. Further, adoptive transfer of PHLPP deficient neutrophils to WT mice is sufficient to potently alleviate the severity of DSS-induced colitis. Our data reveal that PHLPP deficient neutrophils can be uniquely reprogrammed to a state conducive to host inflammation resolution. As a consequence, PHLPP^-/- neutrophils can effectively transfer immune homeostasis in mice subjected to acute colitis. Our findings hold significant and novel insights into the mechanisms by which neutrophils can be effectively reprogrammed into a homeostatic state conducive for treating acute injuries such as septic colitis.

Enhanced tumor immune surveillance through neutrophil reprogramming due to Tollip deficiency

Although the importance of the tumor immune environment for the modulation of tumorigenesis and tumor regression is becoming increasingly clear, most of the research related to tumor-immune therapies has focused on adaptive immune cells, while the role and regulation of innate leukocytes such as neutrophils remains controversial and less defined. Here we observed that the selective deletion of Tollip, a key innate immune-cell modulator, led to enhanced tumor immune surveillance in a chemically induced colorectal cancer model. Tollip-deficient neutrophils significantly elevated T cell activation through enhanced expression of the costimulatory molecule CD80, and reduced expression of the inhibitory molecule PD-L1. Mechanistically, Tollip deficiency increased STAT5 and reduced STAT1, the transcription factors responsible for the expression of CD80 and PD-L1, respectively. Through adoptive transfer, we demonstrate that Tollip-deficient neutrophils, but not Tollip-deficient monocytes, are sufficient to drive enhanced tumor immune surveillance and reduced colorectal cancer burden in vivo. Our data reveal a strategy for the reprogramming of neutrophil functions conducive for the enhancement of the antitumor immune environment.