Thrombopoietin mimetic stimulates bone marrow vascular and stromal niches to mitigate acute radiation syndrome.

BACKGROUND: Acute radiation syndrome (ARS) manifests after exposure to high doses of radiation in the instances of radiologic accidents or incidents. Facilitating regeneration of the bone marrow (BM), namely the hematopoietic stem and progenitor cells (HSPCs), is key in mitigating ARS and multi-organ failure. JNJ-26366821, a PEGylated thrombopoietin mimetic (TPOm) peptide, has been shown as an effective medical countermeasure (MCM) to treat hematopoietic-ARS (H-ARS) in mice. However, the activity of TPOm on regulating BM vascular and stromal niches to support HSPC regeneration has yet to be elucidated. METHODS: C57BL/6J mice (9-14 weeks old) received sublethal or lethal total body irradiation (TBI), a model for H-ARS, by 137Cs or X-rays. At 24 h post-irradiation, mice were subcutaneously injected with a single dose of TPOm (0.3 mg/kg or 1.0 mg/kg) or PBS (vehicle). At homeostasis and on days 4, 7, 10, 14, 18, and 21 post-TBI with and without TPOm treatment, BM was harvested for histology, BM flow cytometry of HSPCs, endothelial (EC) and mesenchymal stromal cells (MSC), and whole-mount confocal microscopy. For survival, irradiated mice were monitored and weighed for 30 days. Lastly, BM triple negative cells (TNC; CD45-, TER-119-, CD31-) were sorted for single-cell RNA-sequencing to examine transcriptomics after TBI with or without TPOm treatment. RESULTS: At homeostasis, TPOm expanded the number of circulating platelets and HSPCs, ECs, and MSCs in the BM. Following sublethal TBI, TPOm improved BM architecture and promoted recovery of HSPCs, ECs, and MSCs. Furthermore, TPOm elevated VEGF-C levels in normal and irradiated mice. Following lethal irradiation, mice improved body weight recovery and 30-day survival when treated with TPOm after 137Cs and X-ray exposure. Additionally, TPOm reduced vascular dilation and permeability. Finally, single-cell RNA-seq analysis indicated that TPOm increased the expression of collagens in MSCs to enhance their interaction with other progenitors in BM and upregulated the regeneration pathway in MSCs. CONCLUSIONS: TPOm interacts with BM vascular and stromal niches to locally support hematopoietic reconstitution and systemically improve survival in mice after TBI. Therefore, this work warrants the development of TPOm as a potent radiation MCM for the treatment of ARS.

Thrombopoietin mimetic stimulates bone marrow vascular and stromal niches to mitigate acute radiation syndrome.

Background: Acute radiation syndrome (ARS) manifests after exposure to high doses of radiation in the instances of radiologic accidents or incidents. Facilitating the regeneration of the bone marrow (BM), namely the hematopoietic stem and progenitor cells (HSPCs), is a key in mitigating ARS and multi-organ failure. JNJ-26366821, a PEGylated thrombopoietin mimetic (TPOm) peptide, has been shown as an effective medical countermeasure (MCM) to treat hematopoietic-ARS (H-ARS) in mice. However, the activity of TPOm on regulating BM vascular and stromal niches to support HSPC regeneration has not yet been elucidated. Methods: C57BL/6J mice (9-14 weeks old) received sublethal or lethal total body irradiation (TBI), a model for H-ARS, by 137Cs or X-rays. At 24 hours post-irradiation, mice were subcutaneously injected with a single dose of TPOm (0.3 mg/kg or 1.0 mg/kg) or PBS (vehicle). At homeostasis and on days 4, 7, 10, 14, 18, and 21 post-TBI with and without TPOm treatment, BM was harvested for histology, BM flow cytometry of HSPCs, endothelial (EC) and mesenchymal stromal cells (MSC), and whole-mount confocal microscopy. For survival, irradiated mice were monitored and weighed for 30 days. Lastly, BM triple negative cells (TNC; CD45-, TER-119-, CD31-) were sorted for single-cell RNA-sequencing to examine transcriptomics after TBI with or without TPOm treatment. Results: At homeostasis, TPOm expanded the number of circulating platelets and HSPCs, ECs, and MSCs in the BM. Following sublethal TBI, TPOm improved BM architecture and promoted recovery of HSPCs, ECs, and MSCs. Furthermore, TPOm elevated VEGF-C levels in normal and irradiated mice. Following lethal irradiation, mice improved body weight recovery and 30-day survival when treated with TPOm after 137Cs and X-ray exposure. Additionally, TPOm reduced vascular dilation and permeability. Finally, single-cell RNA-seq analysis indicated that TPOm increased the expression of collagens in MSCs to enhance their interaction with other progenitors in BM and upregulated the regeneration pathway in MSCs. Conclusions: TPOm interacts with BM vascular and stromal niches to locally support hematopoietic reconstitution and systemically improve survival in mice after TBI. Therefore, this work warrants the development of TPOm as a potent radiation MCM for the treatment of ARS.

Orthovoltage X-Rays Exhibit Increased Efficacy Compared with γ-Rays in Preclinical Irradiation.

Radionuclide irradiators (137Cs and 60Co) are commonly used in preclinical studies ranging from cancer therapy to stem cell biology. Amidst concerns of radiological terrorism, there are institutional initiatives to replace radionuclide sources with lower energy X-ray sources. As researchers transition, questions remain regarding whether the biological effects of γ-rays may be recapitulated with orthovoltage X-rays because different energies may induce divergent biological effects. We therefore sought to compare the effects of orthovoltage X-rays with 1-mm Cu or Thoraeus filtration and 137Cs γ-rays using mouse models of acute radiation syndrome. Following whole-body irradiation, 30-day overall survival was assessed, and the lethal dose to provoke 50% mortality within 30-days (LD50) was calculated by logistic regression. LD50 doses were 6.7 Gy, 7.4 Gy, and 8.1 Gy with 1-mm Cu-filtered X-rays, Thoraeus-filtered X-rays, and 137Cs γ-rays, respectively. Comparison of bone marrow, spleen, and intestinal tissue from mice irradiated with equivalent doses indicated that injury was most severe with 1-mm Cu-filtered X-rays, which resulted in the greatest reduction in bone marrow cellularity, hematopoietic stem and progenitor populations, intestinal crypts, and OLFM4+ intestinal stem cells. Thoraeus-filtered X-rays provoked an intermediate phenotype, with 137Cs showing the least damage. This study reveals a dichotomy between physical dose and biological effect as researchers transition to orthovoltage X-rays. With decreasing energy, there is increasing hematopoietic and intestinal injury, necessitating dose reduction to achieve comparable biological effects. SIGNIFICANCE: Understanding the significance of physical dose delivered using energetically different methods of radiation treatment will aid the transition from radionuclide γ-irradiators to orthovoltage X-irradiators.

CBF oscillations induced by trigeminal nerve stimulation protect the pericontusional penumbra in traumatic brain injury complicated by hemorrhagic shock.

Traumatic peri-contusional penumbra represents crucial targets for therapeutic interventions after traumatic brain injury (TBI). Current resuscitative approaches may not adequately alleviate impaired cerebral microcirculation and, hence, compromise oxygen delivery to peri-contusional areas. Low-frequency oscillations in cerebral blood flow (CBF) may improve cerebral oxygenation in the setting of oxygen deprivation. However, no method has been reported to induce controllable oscillations in CBF and it hasn't been applied as a therapeutic strategy. Electrical stimulation of the trigeminal nerve (TNS) plays a pivotal role in modulating cerebrovascular tone and cerebral perfusion. We hypothesized that TNS can modulate CBF at the targeted frequency band via the trigemino-cerebrovascular network, and TNS-induced CBF oscillations would improve cerebral oxygenation in peri-contusional areas. In a rat model of TBI complicated by hemorrhagic shock, TNS-induced CBF oscillations conferred significant preservation of peri-contusional tissues leading to reduced lesion volume, attenuated hypoxic injury and neuroinflammation, increased eNOS expression, improved neurological recovery and better 10-day survival rate, despite not significantly increasing CBF as compared with those in immediate and delayed resuscitation animals. Our findings indicate that low-frequency CBF oscillations enhance cerebral oxygenation in peri-contusional areas, and play a more significant protective role than improvements in non-oscillatory cerebral perfusion or volume expansion alone.

Extracellular Vesicles for the Treatment of Radiation Injuries.

Normal tissue injury from accidental or therapeutic exposure to high-dose radiation can cause severe acute and delayed toxicities, which result in mortality and chronic morbidity. Exposure to single high-dose radiation leads to a multi-organ failure, known as acute radiation syndrome, which is caused by radiation-induced oxidative stress and DNA damage to tissue stem cells. The radiation exposure results in acute cell loss, cell cycle arrest, senescence, and early damage to bone marrow and intestine with high mortality from sepsis. There is an urgent need for developing medical countermeasures against radiation injury for normal tissue toxicity. In this review, we discuss the potential of applying secretory extracellular vesicles derived from mesenchymal stromal/stem cells, endothelial cells, and macrophages for promoting repair and regeneration of organs after radiation injury.

Hepatic inflammation after burn injury is associated with necroptotic cell death signaling.

BACKGROUND: Burn injury still has a high attributable mortality. The elevated mortality rate of severe burns is still concerning. Hepatic inflammation and injury are common after burns and are associated with poor outcomes. Necroptosis is a programmed cell death linked with inflammation. Thus, assessing necroptotic pathways in the liver can lead to new therapeutic modalities to improve mortality after severe burns. METHODS: Mice underwent 15% total body surface area burn or sham injury. Three hours after burn, the mice were euthanized to collect blood and livers. Histology, injury markers, genes expression, and tissue protein levels were compared between groups. RESULTS: Compared with sham, burned mice had heightened liver inflammatory cell infiltration and edema. Serum aspartate aminotransferase and alanine aminotransferase were increased by 4.9- and 3.4-fold, respectively, in burned mice relative to sham (p < 0.05). Expression of tumor necrosis factor α, interleukin-6, interleukin-1ß, and CXCL1 (KC) genes were elevated in livers of burned mice by 10-, 86-, 10-, and 828-fold, respectively, compared with sham (p < 0.05). Expression of necroptotic genes, namely, receptor-interacting protein kinases 1 and 3, and mixed lineage kinase domain-like in livers of burned mice were increased by 10-, 13-, and 4.5-fold, respectively, relative to sham (p < 0.05). Receptor-interacting protein kinase 1 and phosphorylated mixed lineage kinase domain-like protein levels measured by Western-blot in livers after burn injury were elevated by 22- and 17-fold, respectively, compared with sham (p < 0.05). CONCLUSION: Liver damage occurs early after burns in mice and is associated with elevation of proinflammatory cytokines, chemokine, and proteins involved in the necroptotic pathway. This study suggests that necroptosis plays a role in the pathogenesis of liver failure secondary to burn injury.

The thrombopoietin mimetic JNJ-26366821 increases megakaryopoiesis without affecting malignant myeloid proliferation.

Thrombocytopenia remains a challenge in myeloid malignancies, needing safer and more effective therapies. JNJ-26366821, a pegylated synthetic peptide thrombopoietin (TPO) mimetic not homologous to endogenous TPO, has an in-vitro EC50 of 0.2 ng/mL for the TPO receptor and dose dependently elevates platelets in volunteers. We demonstrate that JNJ-26366821 increases megakaryocytic differentiation and megakaryocytic colony formation in healthy controls and samples from myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). JNJ-26366821 had no effect on proliferation of malignant myeloid cell lines at doses up to 1000 ng/mL and malignant patient-derived mononuclear cells showed no increased cell growth or leukemic colony formation capacity at concentrations between 0.2 ng/mL and 10 ng/mL. Furthermore, JNJ-26366821 did not enhance in-vivo engraftment of leukemic cells in an AML xenotransplantation murine model. Our results show that JNJ-26366821 stimulates megakaryopoiesis without causing proliferation of the malignant myeloid clones in MDS/AML and provides the rationale for clinical testing of JNJ-26366821 in myeloid malignancies.

Anti-interferon-α receptor 1 antibodies attenuate inflammation and organ injury following hemorrhagic shock.

BACKGROUND: Hemorrhagic shock (HS) is a life-threatening condition resulting from rapid and significant loss of intravascular volume, leading to hemodynamic instability and death. Inflammation contributes to the multiple organ injury in HS. Type I interferons (IFNs), such as IFN-α and IFN-ß, are a family of cytokines that regulate the inflammatory response through binding to IFN-α receptor (IFNAR) which consists of IFNAR1 and IFNAR2 chains. We hypothesized that type I IFNs provoke inflammation and worsen organ injury in HS. METHODS: Male C57BL/6 mice (20-25 g) underwent hemorrhage by controlled bleeding via the femoral artery to maintain a mean arterial pressure of 27 ± 2.5 mm Hg for 90 minutes, followed by resuscitation for 30 minutes with two times shed blood volume of Ringer's lactate solution containing 1 mg/kg body weight of anti-IFNAR1 antibody (Ab) or control isotype-matched IgG (IgG). Blood and tissue samples were collected at 20 hours after the resuscitation for various analyses. RESULTS: The expression of IFN-α and IFN-ß mRNAs was significantly elevated in lungs and liver of the mice after HS. The IFNAR1-Ab treatment significantly decreased serum levels of organ injury markers lactate dehydrogenase and aspartate aminotransferase, as well as improved the integrity of lung and liver morphology, compared to the IgG control. The protein levels of proinflammatory cytokines TNF-α and IL-6, and mRNA expression of proinflammatory chemokines monocyte chemoattractant protein (MCP)-1, MCP-2, macrophage inflammatory protein 2 (MIP-2), and keratinocyte cytokine (KC) in the lungs of the HS mice were significantly decreased after treated with IFNAR1-Ab. Moreover, the myeloperoxidase activity and number of apoptotic cells in the lungs of HS mice treated with IFNAR1-Ab were decreased in comparison to the IgG control. CONCLUSION: Administration of IFNAR1-Ab reduces inflammation and tissue injury. Thus, type I IFN signaling may be a potential therapeutic target for mitigating organ dysfunction in patients suffering from HS. STUDY TYPE: Translational animal model.

Trigeminal Nerve Stimulation: A Novel Method of Resuscitation for Hemorrhagic Shock.

OBJECTIVES: To determine if trigeminal nerve stimulation can ameliorate the consequences of acute blood loss and improve survival after severe hemorrhagic shock. DESIGN: Animal study. SETTING: University research laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Severe hemorrhagic shock was induced in rats by withdrawing blood until the mean arterial blood pressure reached 27 ± 1 mm Hg for the first 5 minutes and then maintained at 27 ± 2 mm Hg for 30 minutes. The rats were randomly assigned to either control, vehicle, or trigeminal nerve stimulation treatment groups. The effects of trigeminal nerve stimulation on survival rate, autonomic nervous system activity, hemodynamics, brain perfusion, catecholamine release, and systemic inflammation after severe hemorrhagic shock in the absence of fluid resuscitation were analyzed. MEASUREMENTS AND MAIN RESULTS: Trigeminal nerve stimulation significantly increased the short-term survival of rats following severe hemorrhagic shock in the absence of fluid resuscitation. The survival rate at 60 minutes was 90% in trigeminal nerve stimulation treatment group whereas 0% in control group (p < 0.001). Trigeminal nerve stimulation elicited strong synergistic coactivation of the sympathetic and parasympathetic nervous system as measured by heart rate variability. Without volume expansion with fluid resuscitation, trigeminal nerve stimulation significantly attenuated sympathetic hyperactivity paralleled by increase in parasympathetic tone, delayed hemodynamic decompensation, and improved brain perfusion following severe hemorrhagic shock. Furthermore, trigeminal nerve stimulation generated sympathetically mediated low-frequency oscillatory patterns of systemic blood pressure associated with an increased tolerance to central hypovolemia and increased levels of circulating norepinephrine levels. Trigeminal nerve stimulation also decreased systemic inflammation compared with the vehicle. CONCLUSIONS: Trigeminal nerve stimulation was explored as a novel resuscitation strategy in an animal model of hemorrhagic shock. The results of this study showed that the stimulation of trigeminal nerve modulates both sympathetic and parasympathetic nervous system activity to activate an endogenous pressor response, improve cerebral perfusion, and decrease inflammation, thereby improving survival.

C23, an oligopeptide derived from cold-inducible RNA-binding protein, suppresses inflammation and reduces lung injury in neonatal sepsis.

INTRODUCTION: Neonatal sepsis remains a leading cause of infant mortality. Cold-inducible RNA binding protein (CIRP) is an inflammatory mediator that induces TNF-α production in macrophages. C23 is a CIRP-derived peptide that blocks CIRP from binding its receptor. We therefore hypothesized that treatment with C23 reduces systemic inflammation and protects the lungs in neonatal sepsis. METHODS: Sepsis was induced in C56BL/6 mouse pups (5-7 days) by intraperitoneal injection of adult cecal slurry (0.525 mg/g body weight, LD100). One hour later pups received retroorbital injection of C23 (8 mg/kg) or vehicle (normal saline). Ten hours after sepsis induction, blood and tissues were collected for analysis. RESULTS: C23 treatment resulted in a 58% and 69% reduction in serum levels of proinflammatory cytokines IL-6 and IL-1ß, respectively, and a 40% and 45% reduction of AST and LDH, as compared to vehicle-treated septic pups. In the lungs, C23 treatment reduced expression of cytokines IL-6 and IL-1ß by 78% and 74%. In addition, the mRNA level of neutrophil chemoattractants KC and MIP-2 was reduced by 84% and 74%, respectively. These results corresponded to a reduction in histologic lung injury score. Vehicle-treated pups scored 0.49 ±â€¯0.19, while C23 treatment reduced scores to 0.29 ±â€¯0.12 (p < 0.05; Max = 1). Apoptosis in the lungs, measured by TUNEL assay, was also decreased by 53% with C23 treatment (p < 0.05). CONCLUSIONS: Inhibition of CIRP with C23 treatment is protective in septic neonatal mice as demonstrated by reduced inflammatory markers systemically and in the lung. Therefore, C23 has promising therapeutic potential in treatment of neonatal sepsis. LEVEL OF EVIDENCE: Level I.

Cold-inducible RNA-binding protein-derived peptide C23 attenuates inflammation and tissue injury in a murine model of intestinal ischemia-reperfusion.

BACKGROUND: Cold-inducible RNA-binding protein is a novel damage-associated molecular pattern that causes inflammation. C23, a short peptide derived from cold-inducible RNA-binding protein, has been found to have efficacy in blocking cold-inducible RNA-binding protein's activity. We hypothesized that C23 reduces inflammation and tissue injury induced by intestinal ischemia-reperfusion. METHODS: Male C57BL/6 mice were subjected to 60 minutes of intestinal ischemia by clamping the superior mesenteric artery. Immediately after reperfusion, either normal saline (vehicle) or C23 peptide (8 mg/kg body weight) was injected intraperitoneally. Four hours after reperfusion, blood, intestinal, and lung tissues were collected for analysis of inflammatory and tissue injury parameters. RESULTS: Cold-inducible RNA-binding protein levels in the intestinal tissues were significantly increased following intestinal ischemia-reperfusion. Histologic examination of the intestine revealed a significant reduction in injury score in the C23 group by 48% as compared with the vehicles after intestinal ischemia-reperfusion. The serum levels of lactate dehydrogenase and aspartate aminotransferase were increased in animals that underwent vehicle-treated intestinal ischemia-reperfusion, whereas C23-treated animals exhibited significant reductions by 48% and 53%, respectively. The serum and intestinal tissue levels of tumor necrosis factor α were elevated in vehicle-treated intestinal ischemia-reperfusion mice but decreased by 72% and 69%, respectively, in C23-treated mice. Interleukin-6 mRNA levels in the lungs were reduced by 86% in the C23-treated group in comparison to the vehicle-treated group after intestinal ischemia-reperfusion. Expression of macrophage inflammatory protein 2 and level of myeloperoxidase activity in the lungs were dramatically increased after intestinal ischemia-reperfusion and significantly reduced by 91% and 25%, respectively, in the C23-treated group. CONCLUSION: C23 has potential to be developed into a possible therapy for reperfusion injury after mesenteric ischemia and reperfusion.

The protective role of human ghrelin in sepsis: Restoration of CD4 T cell proliferation.

Decrease of CD4 T cell numbers causes immunosuppression in sepsis. We previously showed the beneficial role of ghrelin in sepsis. We hypothesize that the protective outcome of ghrelin in sepsis is mediated partially through the restoration of CD4 T cells' proliferation. Sepsis was induced in mice by cecal ligation and puncture (CLP). The percentage of CD4 T cells in spleen was assessed by flow cytometry and their proliferation was determined by carboxyfluorescein succinimidyl ester (CSFE). Compared to sham mice, the percentages of splenic CD4 T cells were reduced by 20%, 21%, and 29% at day 1, 2 and 3 after CLP, respectively. Human ghrelin was given to 3 day septic mice by s.c. injection at 5 and 24 h after CLP. Treatment with ghrelin restored the loss of CD4 T cells by increasing their proliferation in septic mice. The expression of cyclin D1 and B1 was significantly increased, while the expression of p57 was decreased in ghrelin-treated mice compared to vehicle-treated mice in sepsis. Treatment with human ghrelin significantly increased the p-AKT levels in the spleen compared to vehicle-treated septic mice. Human ghrelin plays an important role in reestablishing the proliferation of CD4 T cells and serves as a promising therapeutic agent in sepsis.

Inhibition of necroptosis attenuates lung injury and improves survival in neonatal sepsis.

BACKGROUND: Neonatal sepsis represents a unique therapeutic challenge owing to an immature immune system. Necroptosis is a form of programmed cell death that has been identified as an important mechanism of inflammation-induced cell death. Receptor-interacting protein kinase 1 plays a key role in mediating this process. We hypothesized that pharmacologic blockade of receptor-interacting protein kinase 1 activity would be protective in neonatal sepsis. METHODS: Sepsis was induced in C57BL/6 mouse pups (5-7 days old) by intraperitoneal injection of adult cecal slurry. At 1 hour after cecal slurry injection, the receptor-interacting protein kinase 1 inhibitor necrostatin-1 (10 µg/g body weight) or vehicle (5% dimethyl sulfoxide in phosphate buffered saline) was administered via retro-orbital injection. At 20 hours after cecal slurry injection, blood and lung tissues were collected for various analyses. RESULTS: At 20 hours after sepsis induction, vehicle-treated pups showed a marked increase in serum levels of interleukin 6, interleukin 1-beta, and interleukin 18 compared to sham. With necrostatin-1 treatment, serum levels of interleukin 6, interleukin 1-beta, and interleukin 18 were decreased by 77%, 81%, and 63%, respectively, compared to vehicle. In the lungs, sepsis induction resulted in a 232-, 10-, and 2.8-fold increase in interleukin 6, interleukin 1-beta, and interleukin 18 mRNA levels compared to sham, while necrostatin-1 treatment decreased these levels to 40-, 4-, and 0.8-fold, respectively. Expressions of the neutrophil chemokines keratinocyte chemoattractant and macrophage-inflammatory-protein-2 were also increased in the lungs in sepsis, while necrostatin-1 treatment decreased these levels by 81% and 61%, respectively, compared to vehicle. In addition, necrostatin-1 treatment significantly improved the lung histologic injury score and decreased lung apoptosis in septic pups. Finally, treatment with necrostatin-1 increased the 7-day survival rate from 0% in the vehicle-treated septic pups to 29% (P = .11). CONCLUSION: Inhibition of receptor-interacting protein kinase 1 by necrostatin-1 decreases systemic and pulmonary inflammation, decreases lung injury, and increases survival in neonatal mice with sepsis. Targeting the necroptosis pathway might represent a new therapeutic strategy for neonatal sepsis.

A cold-inducible RNA-binding protein (CIRP)-derived peptide attenuates inflammation and organ injury in septic mice.

Cold-inducible RNA-binding protein (CIRP) is a novel sepsis inflammatory mediator and C23 is a putative CIRP competitive inhibitor. Therefore, we hypothesized that C23 can ameliorate sepsis-associated injury to the lungs and kidneys. First, we confirmed that C23 dose-dependently inhibited TNF-α release, IκBα degradation, and NF-κB nuclear translocation in macrophages stimulated with CIRP. Next, we observed that male C57BL/6 mice treated with C23 (8 mg/kg BW) at 2 h after cecal ligation and puncture (CLP) had lower serum levels of LDH, ALT, IL-6, TNF-α, and IL-1ß (reduced by ≥39%) at 20 h after CLP compared with mice treated with vehicle. C23-treated mice also had improved lung histology, less TUNEL-positive cells, lower serum levels of creatinine (34%) and BUN (26%), and lower kidney expression of NGAL (50%) and KIM-1 (86%). C23-treated mice also had reduced lung and kidney levels of IL-6, TNF-α, and IL-1ß. E-selectin and ICAM-1 mRNA was significantly lower in C23-treated mice. The 10-day survival after CLP of vehicle-treated mice was 55%, while that of C23-treated mice was 85%. In summary, C23 decreased systemic, lung, and kidney injury and inflammation, and improved the survival rate after CLP, suggesting that it may be developed as a new treatment for sepsis.

The Protective Effect of A Short Peptide Derived From Cold-Inducible RNA-Binding Protein in Renal Ischemia-Reperfusion Injury.

Extracellular cold-inducible RNA-binding protein (CIRP) functions as damage-associated molecular pattern and has been demonstrated to be responsible in part for the damage occurring after renal ischemia-reperfusion (I/R). A short peptide derived from CIRP, named C23, binds to myeloid differentiation factor 2, a Toll-like receptor 4 coreceptor. We hypothesize that C23 reduces renal ischemia-reperfusion (RIR) injury by blocking CIRP. We observed that pretreatment with C23 significantly decreased the levels of recombinant mouse CIRP-induced tumor necrosis factor-α (TNF-α) in a dose-dependent fashion in cultured macrophages. C57BL/6 mice were subjected to bilateral renal pedicle clamps for 35 min to induce ischemia, followed by reperfusion for 24 h and harvest of blood and renal tissue. C23 peptide (8 mg/kg) or vehicle was injected intraperitoneally at the beginning of reperfusion. Plasma TNF-α, interleukin 1 beta (IL-1ß), and IL-6 levels were decreased in C23-treated RIR mice as compared with vehicle-treated mice by 74%, 85%, and 68%, respectively. Expressions of TNF-α and keratinocyte chemoattractant in the kidneys from C23-treated mice were decreased by 55% and 60%, respectively. Expression of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin in the kidney of C23-treated mice were significantly reduced by 46% and 55%, respectively. Renal tissue histological assessments revealed significant reduction in damage score by 44% in C23-treated mice. Finally, a survival study revealed a significant survival advantage with a 70% survival rate in C23 group vs. 37% in vehicle group. Thus, C23 has potential as a novel therapy for the patients suffering from I/R-induced renal injury.

Deficiency of receptor-interacting protein kinase 3 (RIPK3) attenuates inflammation and organ injury in neonatal sepsis.

INTRODUCTION: Sepsis is the third leading cause of morbidity and mortality in neonates. Sepsis in neonates is characterized as the systemic inflammation owing to infection within the first 28days after birth. The molecular mechanism causing the exaggerated inflammation phenotype in neonates has not been completely elucidated. Receptor interacting protein kinase 3 (RIPK3) is a protein identified as a mediator in programmed necrosis or necroptosis. We hypothesize that RIPK3 could be responsible for the inflammatory response in neonates and that deficiency in the RIPK3 protein attenuates inflammation and organ injury in neonatal sepsis. METHODS: Male and female C57BL6 wild-type (WT) and RIPK3 knock-out (KO) newborn mice aged 5-7days (3-4g body weight) were injected intraperitoneally with 0.9mg/g cecal slurry (CS). At 10h after injection, the newborns were euthanized and blood, the lungs and gut tissues were collected. RESULTS: At 10h after CS injection, serum cytokines IL-6 and IL-1ß in the WT mice were increased by 511- and 43-fold whereas in KO mice, these levels were increased by 166-fold and 22-fold, respectively. Lung IL-1ß in the WT mice increased by 7-fold after CS injection whereas only a 4-fold increase was seen in the KO mice. In the lungs of CS injected KO mice, the injury score, MIP-2 mRNA, myeloperoxidase (MPO) activity and TUNEL staining were significantly reduced by 76%, 70%, 26% and 74%, respectively compared to the CS WT mice. Gut TUNEL staining was also reduced by 80%. CONCLUSION: The deficiency in RIPK3 attenuated serum and lung cytokines, lung injury and neutrophil infiltration and lung and gut apoptosis. These data suggest that RIPK3, in part, is responsible for the systemic inflammatory response in neonatal sepsis.

Cold-inducible RNA-binding protein activates splenic T cells during sepsis in a TLR4-dependent manner.

Cold-inducible RNA-binding protein (CIRP) is a novel inflammatory mediator that stimulates the release of proinflammatory cytokines from macrophages in sepsis. Given the immune dysregulation that characterizes sepsis, the effect of CIRP on other immune cells is an area of increasing interest that has not yet been studied. In the present study, we hypothesized that extracellular CIRP promotes activation of T lymphocytes in the spleen during sepsis. We observed that mice subjected to sepsis by cecal ligation and puncture showed significantly higher expression of the early activation markers CD69 and CD25 at 20 h on CD4+ splenic T cells, and significantly higher CD69 expression on CD8+ splenic T cells compared with sham-operated controls. Furthermore, at 20 h after receiving intravenous injection of recombinant murine CIRP (rmCIRP, 5 mg/kg body weight (BW)) or PBS (vehicle), those mice receiving rmCIRP showed significantly increased expression of CD69 and CD25 on both CD4+ and CD8+ splenic T cells. This effect, however, was not seen in TLR4-deficient mice after rmCIRP injection. In addition, treatment with CIRP predisposed CD4+ T cells to a Th1 hyperinflammatory response profile, and influenced CD8+ T cells toward a cytotoxic profile. Taken together, our findings indicate that CIRP is a proinflammatory mediator that plays an important role in T-cell dysregulation during sepsis in a TLR4-dependent manner.

PYR-41, A Ubiquitin-Activating Enzyme E1 Inhibitor, Attenuates Lung Injury in Sepsis.

During sepsis, systemic inflammation is observed and is associated with multiple organ failure. Activation of NF-κB is crucial for inducing inflammation, which is controlled by degradation of inhibitor molecules (IκB). The ubiquitination proteasome pathway is responsible for the regulation of protein turnover. In this study, we hypothesized that administration of 4[4-(5-nitro-furan-2-ylmethylene)-3, -dioxo-pyrazolidin-1-yl]-benzoic acid ethyl ester (PYR-41), an inhibitor of ubiquitination, could reduce inflammation and organ injury in septic mice. PYR-41 prevented the reduction of IκB protein levels and inhibited release of tumor necrosis factor (TNF)-α in mouse macrophage RAW264.7 cells at 4 h after lipopolysaccharide stimulation dose-dependently. Male C57BL/6 mice were subjected to cecal ligation and puncture (CLP) to induce sepsis. PYR-41 (5 mg/kg) or dimethyl sulfoxide in saline (vehicle) was injected intravenously immediately after CLP. At 20 h after CLP, PYR-41 treatment significantly decreased serum levels of proinflammatory cytokines (TNF-α, interleukin [IL]-1ß, and IL-6) and organ injury markers (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase). PYR-41 significantly improved microscopic structure, and reduced myeloperoxidase activity, number of apoptotic cells and caspase-3 degradation in the lungs of septic mice. The reduced protein levels of IκB in the lungs after CLP were restored by PYR-41 treatment. PYR-41 inhibited the expression of cytokines (IL-1ß and IL-6), chemokines (keratinocyte-derived chemokine and macrophage inflammatory protein 2), and inflammatory mediators (cyclooxygenase-2 and inducible nitric oxide synthase) in the lungs of septic mice. Importantly, PYR-41 significantly increased 10-day survival in septic mice from 42% to 83%. Therefore, targeting ubiquitination by PYR-41 to inhibit NF-κB activation may represent a potential strategy of sepsis therapeutics.

SRT1720, a sirtuin 1 activator, attenuates organ injury and inflammation in sepsis.

BACKGROUND: Sepsis affects 800,000 patients in the United States annually with a mortality rate of up to 30%. Recent studies suggest that sepsis-associated metabolic derangements due to hypoxic tissue injury, impaired oxygen utilization, and mitochondrial dysfunction contribute to mortality. Sirtuin 1 (Sirt1) is a crucial modulator of energy metabolism during starvation states and has anti-inflammatory effects. Here, we hypothesized that SRT1720, a Sirt1 activator, could attenuate the severity of sepsis. MATERIALS AND METHODS: Male C57BL/6 mice (20-25 g) were subjected to cecal ligation and puncture (CLP) to induce sepsis. SRT1720 (5 or 20 mg/kg BW) or 10% dimethyl sulfoxide (vehicle) in 0.2-mL saline was injected intravenously at 5 h after CLP. Control animals were not subjected to any surgery. Blood and liver samples were harvested at 20 h after CLP for analysis. RESULTS: Administration of SRT1720 markedly reduced the serum levels of tissue injury markers (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase) and renal injury markers (blood urea nitrogen and creatinine) in a dose-dependent manner after CLP. Furthermore, the levels of proinflammatory cytokines interleukin (IL)-1ß and IL-6 in the serum and liver were significantly inhibited by SRT1720 treatment after CLP. SRT1720 treatment resulted in a significantly decreased mRNA expression of inflammasome components (nucleotide oligomerization domain-like receptor protein 3, adapter apoptosis-associated speck-like protein containing caspase-recruitment domain, IL-1ß, and IL-18) in the liver, compared with the vehicle group. CONCLUSIONS: SRT1720 treatment attenuates multiorgan injury in septic mice. SRT1720 treatment also decreases the production of proinflammatory cytokines and reduces inflammasome activation. Thus, pharmacologic stimulation of Sirt1 may present a promising therapeutic strategy for sepsis.

Attenuation of hemorrhage-associated lung injury by adjuvant treatment with C23, an oligopeptide derived from cold-inducible RNA-binding protein.

BACKGROUND: Hemorrhagic shock (HS) is an important cause of mortality. HS is associated with an elevated incidence of acute lung injury and acute respiratory distress syndrome, significantly contributing to HS morbidity and mortality. Cold-inducible RNA-binding protein (CIRP) is released into the circulation during HS and can cause lung injury. C23 is a CIRP-derived oligopeptide that binds with high affinity to the CIRP receptor and inhibits CIRP-induced phagocyte secretion of TNF-α. This study was designed to determine whether C23 is able to attenuate HS-associated lung injury. METHODS: C57BL/6 mice were subjected to controlled hemorrhage leading to a mean arterial pressure of 25 ± 3 mm Hg for 90 minutes. Mice were then volume-resuscitated for 30 minutes with normal saline solution alone (vehicle) or plus adjuvant treatment with C23 (8 mg/kg BW). At 4.5 hours after resuscitation, the blood and lungs were harvested. RESULTS: Serum levels of organ injury markers lactate dehydrogenase, aspartate aminotransferase were significantly elevated in hemorrhaged mice receiving vehicle and were reduced by 51.3% and 52.2% in mice adjuvantly treated with C23, respectively. Similarly, lung mRNA levels of IL-1ß, TNF-α, and IL-6, and lung myeloperoxidase activity were elevated after HS and reduced by 66.1%, 54.4%, 69.7%, and 24.3%, respectively, in mice treated with C23. Adjuvant treatment with C23 also decreased the lung histology score by 33.9%, lung extravasation of albumin carrying Evans blue dye by 36.8%, and the protein level of intercellular adhesion molecule-1, and indicator of vascular endothelial cell activation, by 40.3%. CONCLUSION: Together, these results indicate that adjuvant treatment with the CIRP-derived oligopeptide C23 is able to improve lung inflammation and vascular endothelial activation secondary to HS, lending support to the development of CIRP-targeting adjuvant treatments to minimize lung injury after HS.