Rho-kinase regulates adhesive and mechanical mechanisms of pulmonary recruitment of neutrophils in abdominal sepsis

Diagnostic and prognostic value of disulfidptosis-related genes in sepsis

Background

Sepsis is a disease associated with high morbidity and mortality rates, especially among the elderly and patients in intensive care units. Disulfidptosis, a newly identified form of cell death triggered by disulfide stress, is emerging as a significant factor in disease progression. This study aimed to explore the diagnostic and prognostic value of disulfidptosis-related genes in sepsis.

Methods

We obtained two datasets from the Gene Expression Omnibus (GEO) database to conduct our analysis. Functional enrichment analysis was performed to identify relevant biological pathways. A protein-protein interaction network was constructed to identify hub genes critical to sepsis. Additionally, we analyzed the immune infiltration status in sepsis patients. The diagnostic value of these hub genes for sepsis was evaluated using nomograms, receiver operating characteristic (ROC) curves, and calibration curves in both training and validation datasets. Finally, a miRNA-immune-related hub genes (miRNA-IHGs) regulatory network was developed to elucidate the synergistic interactions between miRNAs and their target genes.

Results

A total of 3,469 differentially expressed genes (DEGs) were identified, of which seven were related to disulfidptosis (DR-DEGs). Functional enrichment analysis showed that DR-DEGs were significantly enriched in pathways related to actin dynamics. Five hub genes (MYH10, ACTN4, MYH9, FLNA, and IQGAP1) were identified as central to these processes. The analysis of immune infiltration revealed significantly lower levels of 11 immune cell types, while macrophages and regulatory T cells were significantly elevated in sepsis patients. The area under the ROC curves (AUCs) of the IHGs risk prediction model were 0.917 and 0.894 for the training and validation sets, respectively. A miRNA-IHGs regulatory network, comprising 17 nodes and 27 edges, was constructed, with MYH9 being the most frequently regulated by miRNAs.

Conclusion

The pathophysiological process of sepsis appears to involve disulfidptosis, highlighting it as a potential new therapeutic targets for sepsis management.

Biomaterial-based mechanical regulation facilitates scarless wound healing with functional skin appendage regeneration

Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages, ultimately impairing its normal physiological function. Accumulating evidence underscores the potential of targeted modulation of mechanical cues to enhance skin regeneration, promoting scarless repair by influencing the extracellular microenvironment and driving the phenotypic transitions. The field of skin repair and skin appendage regeneration has witnessed remarkable advancements in the utilization of biomaterials with distinct physical properties. However, a comprehensive understanding of the underlying mechanisms remains somewhat elusive, limiting the broader application of these innovations. In this review, we present two promising biomaterial-based mechanical approaches aimed at bolstering the regenerative capacity of compromised skin. The first approach involves leveraging biomaterials with specific biophysical properties to create an optimal scarless environment that supports cellular activities essential for regeneration. The second approach centers on harnessing mechanical forces exerted by biomaterials to enhance cellular plasticity, facilitating efficient cellular reprogramming and, consequently, promoting the regeneration of skin appendages. In summary, the manipulation of mechanical cues using biomaterial-based strategies holds significant promise as a supplementary approach for achieving scarless wound healing, coupled with the restoration of multiple skin appendage functions.

Sodium butyrate ameliorates sepsis-associated lung injury by enhancing gut and lung barrier function in combination with modulation of CD4+Foxp3+ regulatory T cells

Sepsis-associated lung injury often coexists with intestinal dysfunction. Butyrate, an essential gut microbiota metabolite, participates in gut-lung crosstalk and has immunoregulatory effects. This study aims to investigate the effect and mechanism of sodium butyrate (NaB) on lung injury. Sepsis-associated lung injury was established in mice by cecal ligation and puncture (CLP). Mice in treatment groups received NaB gavage after surgery. The survival rate, the oxygenation index and the lung wet-to-dry weight (W/D) ratio were calculated respectively. Pulmonary and intestinal histologic changes were observed. The total protein concentration in bronchoalveolar lavage fluid (BALF) was measured, and inflammatory factors in serum and BALF were examined. Diamine oxidase (DAO), lipopolysaccharide (LPS), and surfactant-associated protein D (SP-D) levels in serum and amphiregulin in lung tissue were assessed. Intercellular junction protein expression in the lung and intestinal tissues were examined. Changes in immune cells were analyzed. NaB treatment improved the survival rate, the oxygenation index and the histologic changes. NaB decreased the W/D ratio, total protein concentration, and the levels of proinflammatory cytokines, as well as SP-D, DAO and LPS, while increased the levels of anti-inflammatory cytokines and amphiregulin. The intercellular junction protein expression were improved by NaB. Furthermore, the CD4+/CD8+ T-cell ratio and the proportion of CD4+Foxp3+ regulatory T cells (Tregs) were increased by NaB. Our data suggested that NaB gavage effectively improved the survival rate and mitigated lung injury in CLP mice. The possible mechanism was that NaB augmented CD4+Foxp3+ Tregs and enhanced the barrier function of the gut and the lung.

Actin-related protein 2/3 complex regulates neutrophil extracellular trap expulsion and lung damage in abdominal sepsis

Neutrophil extracellular trap (NET) formation is a key feature in sepsis. The aim of the present study was to examine the role of the actin cytoskeleton in regulating the expulsion of NETs. Actin-related protein 2/3 (Arp 2/3) complex is an important regulator of F-actin polymerization. Co-incubation with CK666, a specific Arp 2/3 inhibitor, decreased PMA-induced NET formation in vitro. CK666 not only abolished F-actin polymerization but also caused intracellular retention of NETs. Inhibition of Arp 2/3 reduced NET formation on circulating neutrophils and in the bronchoalveolar space in mice undergoing cecal ligation and puncture (CLP). Notably, treatment with CK666 attenuated CLP-induced neutrophil recruitment, edema formation and tissue damage in the lungs. Moreover, Arp 2/3 inhibition decreased levels of CXCL-1 and interleukin-6 in the lung and plasma of septic animals. Taken together, this study shows that expulsion of NETs is regulated by the actin cytoskeleton and that inhibition of Arp 2/3-dependent F-actin polymerization not only decrease NET formation but also protect against pathological inflammation and tissue damage in septic lung injury. Thus, we suggest that targeting NET release is a novel and useful way to ameliorate lung damage in abdominal sepsis.

Rho-Proteins and Downstream Pathways as Potential Targets in Sepsis and Septic Shock: What Have We Learned from Basic Research

Sepsis and septic shock are associated with acute and sustained impairment in the function of the cardiovascular system, kidneys, lungs, liver, and brain, among others. Despite the significant advances in prevention and treatment, sepsis and septic shock sepsis remain global health problems with elevated mortality rates. Rho proteins can interact with a considerable number of targets, directly affecting cellular contractility, actin filament assembly and growing, cell motility and migration, cytoskeleton rearrangement, and actin polymerization, physiological functions that are intensively impaired during inflammatory conditions, such as the one that occurs in sepsis. In the last few decades, Rho proteins and their downstream pathways have been investigated in sepsis-associated experimental models. The most frequently used experimental design included the exposure to bacterial lipopolysaccharide (LPS), in both in vitro and in vivo approaches, but experiments using the cecal ligation and puncture (CLP) model of sepsis have also been performed. The findings described in this review indicate that Rho proteins, mainly RhoA and Rac1, are associated with the development of crucial sepsis-associated dysfunction in different systems and cells, including the endothelium, vessels, and heart. Notably, the data found in the literature suggest that either the inhibition or activation of Rho proteins and associated pathways might be desirable in sepsis and septic shock, accordingly with the cellular system evaluated. This review included the main findings, relevance, and limitations of the current knowledge connecting Rho proteins and sepsis-associated experimental models.

Impact of plasma 5-hydroxyindoleacetic acid, a serotonin metabolite, on clinical outcome in septic shock, and its effect on vascular permeability

Septic shock is characterized by dysregulated vascular permeability. We hypothesized that the vascular permeability of endothelial cells (ECs) would be regulated by serotonin via serotonin-Rho-associated kinase (ROCK) signaling. We aimed to determine the impact of 5-hydroxyindoleacetic acid (5-HIAA) on septic shock as a novel biomarker. Plasma 5-HIAA levels and disease severity indices were obtained from 47 patients with sepsis. The association between 5-HIAA levels and severity indices was analyzed. Permeability upon serotonin stimulation was determined using human pulmonary microvascular ECs. 5-HIAA were significantly higher in septic shock patients than in patients without shock or healthy controls (p = 0.004). These elevated levels were correlated with severity indexes (SOFA score [p < 0.001], APACHE II [p < 0.001], and PaO₂:FiO₂ [p = 0.02]), and longitudinally associated with worse clinical outcomes (mechanical ventilation duration [p = 0.009] and ICU duration [p = 0.01]). In the experiment, serotonin increased the permeability of ECs, which was inhibited by the ROCK inhibitor (p < 0.001). Serotonin increases vascular permeability of ECs via ROCK signaling. This suggests a novel mechanism by which serotonin disrupts endothelial barriers via ROCK signaling and causes the pathogenesis of septic shock with a vascular leak. Serotonin serves as a novel biomarker of vascular permeability.

Acute lung injury: The therapeutic role of Rho kinase inhibitors

Acute lung injury (ALI) is a pulmonary illness with high rates of mortality and morbidity. Rho GTPase and its downstream effector, Rho kinase (ROCK), have been demonstrated to be involved in cell adhesion, motility, and contraction which can play a role in ALI. The electronic databases of Google Scholar, Scopus, PubMed, and Web of Science were searched to obtain relevant studies regarding the role of the Rho/ROCK signaling pathway in the pathophysiology of ALI and the effects of specific Rho kinase inhibitors in prevention and treatment of ALI. Upregulation of the RhoA/ROCK signaling pathway causes an increase of inflammation, immune cell migration, apoptosis, coagulation, contraction, and cell adhesion in pulmonary endothelial cells. These effects are involved in endothelium barrier dysfunction and edema, hallmarks of ALI. These effects were significantly reversed by Rho kinase inhibitors. Rho kinase inhibition offers a promising approach in ALI [ARDS] treatment.

ROCK Inhibition Drives Resolution of Acute Inflammation by Enhancing Neutrophil Apoptosis

Uncontrolled inflammation leads to tissue damage and it is central for the development of chronic inflammatory diseases and autoimmunity. An acute inflammatory response is finely regulated by the action of anti-inflammatory and pro-resolutive mediators, culminating in the resolution of inflammation and restoration of homeostasis. There are few studies investigating intracellular signaling pathways associated with the resolution of inflammation. Here, we investigate the role of Rho-associated kinase (ROCK), a serine/threonine kinase, in a model of self-resolving neutrophilic inflammatory. We show that ROCK activity, evaluated by P-MYPT-1 kinetics, was higher during the peak of lipopolysaccharide-induced neutrophil influx in the pleural cavity of mice. ROCK inhibition by treatment with Y-27632 decreased the accumulation of neutrophils in the pleural cavity and was associated with an increase in apoptotic events and efferocytosis, as evaluated by an in vivo assay. In a model of gout, treatment with Y-27632 reduced neutrophil accumulation, IL-1β levels and hypernociception in the joint. These were associated with reduced MYPT and IκBα phosphorylation levels and increased apoptosis. Finally, inhibition of ROCK activity also induced apoptosis in human neutrophils and destabilized cytoskeleton, extending the observed effects to human cells. Taken together, these data show that inhibition of the ROCK pathway might represent a potential therapeutic target for neutrophilic inflammatory diseases.

Exogenous glutamine impairs neutrophils migration into infections sites elicited by lipopolysaccharide by a multistep mechanism

Glutamine (GLN) is the most abundant free amino acid in the body, and is considered as a conditionally essential amino acid under stress conditions, acting as an important modulator of the immune response. We here investigated the role of exogenous GLN treatment on leukocyte migration after the onset of endotoxemia and the intracellular mechanisms of GLN actions on neutrophils. Two in vivo models of endotoxemia caused by lipopolysaccharide of Escherichia coli (LPS) injection were carried out in male outbred Balb/C mice 2-3 months old, as follow: (1) LPS (50 μg/kg) was intravenously injected 1 h prior to intravenous injection of GLN (0.75 mg/kg) and samples were collected 2 h later to investigate the role of GLN on the acute lung inflammation; (2) LPS (1 mg/kg) was intraperitoneally injected 1 h prior to intravenous injection of GLN (0.75 mg/kg) and samples were collected 18 h later to measure the effects of GLN on local and later phases of inflammation in the peritoneum. Results showed that GLN administration reduced the number of neutrophils in the inflamed lungs, partially recovery of the reduced number of leukocytes in the blood; reduced adhesion molecules on lung endothelium and on circulating neutrophils. Moreover, GLN treatment diminished the number of neutrophils, levels of chemotactic cytokine CXCL2 in the inflamed peritoneum, and neutrophils collected from the peritoneum of GLN-treated mice presented lower levels of Rho, Rac, and JNK. Together, our data show novel mechanisms involved in the actions of GLN on neutrophils migration.

Neutrophil Extracellular Traps Induce Trypsin Activation, Inflammation, and Tissue Damage in Mice With Severe Acute Pancreatitis

BACKGROUND & AIMS

Neutrophils are involved in the development of acute pancreatitis (AP), but it is not clear how neutrophil-induced tissue damage is regulated. In addition to secreting antimicrobial compounds, activated neutrophils eliminate invading microorganisms by expelling nuclear DNA and histones to form extracellular web-like structures called neutrophil extracellular traps (NETs). However, NETs have been reported to contribute to organ dysfunction in patients with infectious diseases. We investigated whether NETs contribute to the development of AP in mice.

METHODS

AP was induced in C57BL/6 mice by infusion of taurocholate into the pancreatic duct or by intraperitoneal administration of L-arginine. Pancreata were collected and extracellular DNA was detected by Sytox green staining, levels of CXC chemokines, histones, and cytokines also were measured. Cell-free DNA was quantified in plasma samples. Signal transducer and activator of transcription 3 phosphorylation and trypsin activation were analyzed in isolated acinar cells. NETs were depleted by administration of DNase I to mice. Plasma was obtained from healthy individuals (controls) and patients with severe AP.

RESULTS

Infusion of taurocholate induced formation of NETs in pancreatic tissues of mice and increased levels of cell-free DNA in plasma. Neutrophil depletion prevented taurocholate-induced deposition of NETs in the pancreas. Administration of DNase I to mice reduced neutrophil infiltration and tissue damage in the inflamed pancreas and lung, and decreased levels of blood amylase, macrophage inflammatory protein-2, interleukin 6, and high-mobility groups protein 1. In mice given taurocholate, DNase I administration also reduced expression of integrin α M (macrophage-1 antigen) on circulating neutrophils. Similar results occurred in mice with L-arginine-induced AP. Addition of NETs and histones to acinar cells induced formation of trypsin and activation of signal transducer and activator of transcription 3; these processes were blocked by polysialic acid. Patients with severe AP had increased plasma levels of NET components compared with controls.

CONCLUSIONS

NETs form in the pancreata of mice during the development of AP, and NET levels are increased in plasma from patients with AP, compared with controls. NETs regulate organ inflammation and injury in mice with AP, and might be targeted to reduce pancreatic tissue damage and inflammation in patients.

Farnesyltransferase regulates neutrophil recruitment and tissue damage in acute pancreatitis

OBJECTIVES

The signaling mechanisms controlling organ damage in the pancreas in severe acute pancreatitis (AP) remain elusive. Herein, we examined the role of farnesyltransferase signaling in AP.

METHODS

Pancreatitis was provoked by the infusion of taurocholate into the pancreatic duct in C57BL/6 mice. Animals were treated with a farnesyltransferase inhibitor FTI-277 (25 mg/kg) before pancreatitis induction.

RESULTS

FTI-277 decreased the blood amylase levels, pancreatic neutrophil infiltration, hemorrhage, and edema formation in the pancreas in mice challenged with taurocholate. Farnesyltransferase inhibition reduced the myeloperoxidase levels in the pancreas and lungs in response to taurocholate infusion. However, FTI-277 had no effect on the taurocholate-provoked formation of macrophage inflammatory protein-2 in the pancreas. Interestingly, farnesyltransferase inhibition abolished the neutrophil expression of macrophage-1 antigen in mice with pancreatitis. In addition, FTI-277 decreased the taurocholate-induced activation of the rat sarcoma protein in the pancreas. An important role of farnesyltransferase was confirmed in L-arginine-induced pancreatitis.

CONCLUSIONS

These results demonstrate that farnesyltransferase signaling plays a significant role in AP by regulating neutrophil infiltration and tissue injury via the neutrophil expression of macrophage-1 antigen. Thus, our findings not only elucidate novel signaling mechanisms in pancreatitis but also suggest that farnesyltransferase might constitute a target in the management of severe AP.

Inhibition of geranylgeranyltransferase attenuates neutrophil accumulation and tissue injury in severe acute pancreatitis

Leukocyte infiltration and acinar cell necrosis are hallmarks of severe AP, but the signaling pathways regulating inflammation and organ injury in the pancreas remain elusive. In the present study, we investigated the role of geranylgeranyltransferase in AP. Male C57BL/6 mice were treated with a geranylgeranyltransferase inhibitor GGTI-2133 (20 mg/kg) prior to induction of pancreatitis by infusion of taurocholate into the pancreatic duct. Pretreatment with GGTI-2133 reduced plasma amylase levels, pancreatic neutrophil recruitment, hemorrhage, and edema formation in taurocholate-evoked pancreatitis. Moreover, administration of GGTI-2133 decreased the taurocholate-induced increase of MPO activity in the pancreas and lung. Treatment with GGTI-2133 markedly reduced levels of CXCL2 in the pancreas and IL-6 in the plasma in response to taurocholate challenge. Notably, geranylgeranyltransferase inhibition abolished neutrophil expression of Mac-1 in mice with pancreatitis. Finally, inhibition of geranylgeranyltransferase had no direct effect on secretagogue-induced activation of trypsinogen in pancreatic acinar cells in vitro. A significant role of geranylgeranyltransferase was confirmed in an alternate model of AP induced by L-arginine challenge. Our findings show that geranylgeranyltransferase regulates neutrophil accumulation and tissue damage via expression of Mac-1 on neutrophils and CXCL2 formation in AP. Thus, these results reveal new signaling mechanisms in pancreatitis and indicate that targeting geranylgeranyltransferase might be an effective way to ameliorate severe AP.

Distinct patterns of leukocyte recruitment in the pulmonary microvasculature in response to local and systemic inflammation

The mechanisms of leukocyte recruitment in the pulmonary microvasculature in response to local and systemic inflammation remain elusive. Male C57BL/6 mice received lipopolysaccharide (LPS) intrapulmonary (intratracheally, it) or systemically (intravenously, iv) for 1–18 h. Leukocyte responses in lung were analyzed by use of intravital fluorescence microscopy. Plasma and lung levels of CXC chemokines as well as Mac-1 and F-actin expression in leukocytes and bronchoalveolar leukocytes were quantified. Venular leukocyte rolling was markedly increased in response to local LPS but only marginally after systemic LPS. Leukocyte adhesion in venules was enhanced in both groups although adhesion was higher in mice receiving LPS intratracheally compared with LPS intravenously. Systemic LPS caused more leukocytes trapping in capillaries compared with local LPS. The ratio of adherent leukocytes in venules compared with capillaries was higher in response to local LPS, suggesting that leukocytes were more prone to accumulate in venules in local inflammation and in capillaries in systemic inflammation. Systemic LPS triggered higher F-actin formation and Mac-1 expression in leukocytes compared with local LPS. Local and systemic LPS caused similar increases in CXC chemokines in the lung whereas intravenous endotoxin provoked higher levels of CXC chemokines in the circulation. Interestingly, intratracheal LPS increased recruitment of leukocytes in the alveolar space whereas intravenous LPS was ineffective in promoting leukocyte accumulation in the bronchoalveolar space. In conclusion, our data demonstrate that pulmonary microvascular recruitment of leukocytes differs in local and systemic inflammation, which might be related to premature activation and stiffening of circulating leukocytes in endotoxemia.

Exogenous carbon monoxide attenuates inflammatory responses in the small intestine of septic mice

AIM: To determine whether the carbon monoxide (CO)-releasing molecules (CORM)-liberated CO suppress inflammatory responses in the small intestine of septic mice.

METHODS: The C57BL/6 mice (male, n = 36; weight 20 ± 2 g) were assigned to four groups in three respective experiments. Sepsis in mice was induced by cecal ligation and puncture (CLP) (24 h). Tricarbonyldichlororuthenium (II) dimer (CORM-2) (8 mg/kg, i.v.) was administrated immediately after induction of CLP. The levels of inflammatory cytokines [interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α)] in tissue homogenates were measured with enzyme-linked immunosorbent assay. The levels of malondialdehyde (MDA) in the tissues were determined. The levels of nitric oxide (NO) in tissue homogenate were measured and the expression levels of intercellular adhesion molecule 1 (ICAM-1) and inducible nitric oxide synthase (iNOS) in the small intestine were also assessed. NO and IL-8 levels in the supernatants were determined after the human adenocarcinoma cell line Caco-2 was stimulated by lipopolysaccharide (LPS) (10 g/mL) for 4 h in vitro.

RESULTS: At 24 h after CLP, histological analysis showed that the ileum and jejunum from CLP mice induced severe edema and sloughing of the villous tips, as well as infiltration of inflammatory cells into the mucosa. Semi-quantitative analysis of histological samples of ileum and jejunum showed that granulocyte infiltration in the septic mice was significantly increased compared to that in the sham group. Administration of CORM-2 significantly decreased granulocyte infiltration. At 24 h after CLP, the tissue MDA levels in the mid-ileum and mid-jejunum significantly increased compared to the sham animals (103.68 ± 23.88 nmol/mL vs 39.66 ± 8.23 nmol/mL, 89.66 ± 9.98 nmol/mL vs 32.32 ± 7.43 nmol/mL, P < 0.01). In vitro administration of CORM-2, tissue MDA levels were significantly decreased (50.65 ± 11.46 nmol/mL, 59.32 ± 6.62 nmol/mL, P < 0.05). Meanwhile, the tissue IL-1β and TNF-α levels in the mid-ileum significantly increased compared to the sham animals (6.66 ± 1.09 pg/mL vs 1.67 ± 0.45 pg/mL, 19.34 ± 3.99 pg/mL vs 3.98 ± 0.87 pg/mL, P < 0.01). In vitro administration of CORM-2, tissue IL-1β and TNF-α levels were significantly decreased (3.87 ± 1.08 pg/mL, 10.45 ± 2.48 pg/mL, P < 0.05). The levels of NO in mid-ileum and mid-jejunum tissue homogenate were also decreased (14.69 ± 2.45 nmol/mL vs 24.36 ± 2.97 nmol/mL, 18.47 ± 2.47 nmol/mL vs 27.33 ± 3.87 nmol/mL, P < 0.05). The expression of iNOS and ICAM-1 in the mid-ileum of septic mice at 24 h after CLP induction significantly increased compared to the sham animals. In vitro administration of CORM-2, expression of iNOS and ICAM-1 were significantly decreased. In parallel, the levels of NO and IL-8 in the supernatants of Caco-2 stimulated by LPS was markedly decreased in CORM-2-treated Caco-2 cells (2.22 ± 0.12 nmol/mL vs 6.25 ± 1.69 nmol/mL, 24.97 ± 3.01 pg/mL vs 49.45 ± 5.11 pg/mL, P < 0.05).

CONCLUSION: CORM-released CO attenuates the inflammatory cytokine production (IL-1β and TNF-α), and suppress the oxidative stress in the small intestine during sepsis by interfering with protein expression of ICAM-1 and iNOS.