Neutrophil recruitment by chemokines Cxcl1/KC and Cxcl2/MIP2: Role of Cxcr2 activation and glycosaminoglycan interactions

Abstract

Chemokines play a crucial role in combating microbial infection by recruiting blood neutrophils to infected tissue. In mice, the chemokines Cxcl1/KC and Cxcl2/MIP2 fulfill this role. Cxcl1 and Cxcl2 exist as monomers and dimers, and exert their function by activating the Cxcr2 receptor and binding glycosaminoglycans (GAGs). Here, we characterized Cxcr2 G protein and-arrestin activities, and GAG heparan sulfate (HS) interactions of Cxcl1 and Cxcl2 and of the trapped dimeric variants. To understand how Cxcr2 and GAG interactions impact in vivo function, we characterized their neutrophil recruitment activity to the peritoneum, Cxcr2 and CD11b levels on peritoneal and blood neutrophils, and transport profiles out of the peritoneum. Cxcl2 variants compared with Cxcl1 variants were more potent for Cxcr2 activity. Native Cxcl1 compared with native Cxcl2 and dimers compared with native proteins bound HS with higher affinity. Interestingly, recruitment activity between native Cxcl1 and Cxcl2, between dimers, and between the native protein and the dimer could be similar or very different depending on the dose or the time point. These data indicate that peritoneal neutrophil recruitment cannot be solely attributed to Cxcr2 or GAG interactions, and that the relationship between recruited neutrophils, Cxcr2 activation, GAG interactions, and chemokine levels is complex and highly context dependent. We propose that the ability of Cxcl1 and Cxcl2 to reversibly exist as monomers and dimers and differences in their Cxcr2 activity and GAG interactions coordinate neutrophil recruitment and activation, which play a critical role for successful resolution of inflammation.

Paeoniflorin and Hydroxysafflor Yellow A in Xuebijing Injection Attenuate Sepsis-Induced Cardiac Dysfunction and Inhibit Proinflammatory Cytokine Production

“…Both CXCL1 and CXCL2 can be secreted by monocytes and neutrophils at the site of inflammation. They function through the chemokine receptor CXCR2 to act as chemotactic agents for leukocytes and hematopoietic cells (Sawant et al, 2020).…”

Structural basis of a chemokine heterodimer binding to glycosaminoglycans

“…Cxcl1 (also known as mouse CXCL1/mCXCL1 and KC) and Cxcl2 (also known as mouse CXCL2/mCXCL2 and MIP2) are the major chemokines that orchestrate neutrophil recruitment in mice (18)(19)(20). We have previously shown that Cxcl1 and Cxcl2 dimers bind GAGs with higher affinity and that their GAG interactions and neutrophil recruitment profiles are different (29,30). Our current study indicates that Cxcl1 and Cxcl2 form a heterodimer with a propensity comparable to homodimers.…”

“…We used a ~9 kDa HS (Iduron) and a ~15 kDa heparin (Calbiochem). The GAGs were biotinylated using the EZ-Link Biotin LC Hydrazide reagent, immobilized to a Sensor Chip SA, and binding measurements were carried out as described (30). We used two different chips -one containing ~80 RU of immobilized GAG defined as a lowdensity chip and the other ~220-250 RU of immobilized GAG defined as a high-density chip.…”

Nociceptive sensory neurons promote CD8 T cell responses to HSV-1 infection

“…However, viral clearance from the skin was similar in control DTA mice and Nav 1.8 -DTA mice, excluding the possibility of the larger lesions in nociceptor-deficient mice being due to uncontrolled viral replication. This phenotype was associated with higher levels of chemokines and inflammatory cytokines, including CXCL1, which is known to attract neutrophils to tissues 38 . Consistent with these data, neutrophil numbers in the skin remained higher in nociceptor-deficient mice than in their control DTA littermates, suggesting that this persistent neutrophil influx plays an important role in the observed extensive skin damage.…”

“…associated with higher levels of chemokines and inflammatory cytokines, including CXCL1, which is known to attract neutrophils to tissues 38 . Consistent with these data, neutrophil numbers in the skin remained higher in nociceptor-deficient mice than in their control DTA littermates, suggesting that this persistent neutrophil influx plays an important role in the observed extensive skin damage.…”