Histidine-Rich Glycoprotein Prevents Septic Lethality through Regulation of Immunothrombosis and Inflammation

Abstract

Sepsis is a major cause of death worldwide. We show that a plasma protein histidine-rich glycoprotein (HRG) was decreased significantly in septic mice with cecal ligation and puncture (CLP) and supplementary treatment of septic mice with exogenous HRG improved survival, with strong inhibition of tight attachment of neutrophils to pulmonary vasculatures, subsequent immunothrombosis, DIC state, lung inflammation, hypercytokinemia, and activation of vascular endothelial cells (VECs). In contrast, knockdown of HRG by siRNA exacerbated lethality. Purified human HRG reversibly induced morphological changes in human neutrophils in vitro; induction of spherical shape with reduced microvilli and adhesiveness to VECs. HRG maintained the passage of neutrophils through microcapillaries and abolished production of reactive oxygen species. These results suggested that the supplementary therapy with HRG may provide a novel strategy for the treatment of sepsis through suppression of excessive systemic inflammation and immunothrombosis by keeping circulating neutrophils quiescent and preventing uncontrolled activation of VECs.

Histidine‐rich glycoprotein ameliorates endothelial barrier dysfunction through regulation of NF‐κB and MAPK signal pathway

“…IL‐8 is a well‐known neutrophil chemotactic factor. The inhibitory effects of HRG on the IL‐8 secretion and expression also supported the previous finding that HRG can strongly suppress the adhesion of neutrophils to lung vasculatures in septic mice (Wake et al, ). Moreover, the suppressive effects of HRG on hypercytokinaemia in septic mice were also observed in the LPS‐injected mice (Figure S4).…”

“…Moreover, the suppressive effects of HRG on hypercytokinaemia in septic mice were also observed in the LPS‐injected mice (Figure S4). These findings support the hypothesis that HRG may exert anti‐septic effects through the regulation of cytokine production and barrier dysfunction in vascular endothelial cells, in addition to a strong regulator role for neutrophils (Wake et al, ).…”

“…Moreover, our previous study (Wake et al, ) already proved that the systemic injection of HRG significantly reduced the cytokine levels in the septic mice compared with control HSA‐injected group. In the present study, the effects of HRG on the serum cytokine levels in LPS‐injected mice were also determined with cytometric bead array.…”

“…injection of LPS (10 mg·kg −1 ) and was used for experiments 12 hr thereafter (London et al, ; Xu, Wu, Hack, Bao, & Cunningham, ). The CLP septic animal models were established as described in our previous study (Wake et al, ). Briefly, the mice were anaesthetized with 3% isoflurane in 48.5% N 2 O and 48.5% O 2 , and a ligature was set below the ileocaecal valve.…”

“…Shannon et al () demonstrated that HRG decreased the mortality of a septic mouse model with Streptococcus pyogenes ‐induced abscesses by the killing and trapping of bacteria in the abscess sites. Wake et al () demonstrated that HRG prevents septic lethality through the regulation of neutrophils and the inhibition of the strong attachment of neutrophils to vascular endothelial cells. In recent clinical studies, HRG was further proposed as a new biomarker to predict the outcome of a sepsis patient (Kuroda et al, ; Nishibori, Wake, & Morimatsu, ).…”