Ulinastatin inhibited sepsis-induced spinal inflammation to alleviate peripheral neuromuscular dysfunction in an experimental rat model of neuromyopathy

Advances in molecular agents targeting toll-like receptor 4 signaling pathways for potential treatment of sepsis

Sepsis is a systemic inflammatory response syndrome caused by an infection. Toll-like receptor 4 (TLR4) is activated by endogenous molecules released by injured or necrotic tissues. Additionally, TLR4 is remarkably sensitive to infection of various bacteria and can rapidly stimulate host defense responses. The TLR4 signaling pathway plays an important role in sepsis by activating the inflammatory response. Accordingly, as part of efforts to improve the inflammatory response and survival rate of patients with sepsis, several drugs have been developed to regulate the inflammatory signaling pathways mediated by TLR4. Inhibition of TLR4 signal transduction can be directed toward either TLR4 directly or other proteins in the TLR4 signaling pathway. Here, we review the advances in the development of small-molecule agents and peptides targeting regulation of the TLR4 signaling pathway, which are characterized according to their structural characteristics as polyphenols, terpenoids, steroids, antibiotics, anthraquinones, inorganic compounds, and others. Therefore, regulating the expression of the TLR4 signaling pathway and modulating its effects has broad prospects as a target for the treatment of lung, liver, kidneys, and other important organs injury in sepsis.

ß1-adrenergic blockers preserve neuromuscular function by inhibiting the production of extracellular traps during systemic inflammation in mice

Severe inflammation via innate immune system activation causes organ dysfunction. Among these, the central nervous system (CNS) is particularly affected by encephalopathies. These symptoms are associated with the activation of microglia and a potential infiltration of leukocytes. These immune cells have recently been discovered to have the ability to produce extracellular traps (ETs). While these components capture and destroy pathogens, deleterious effects occur such as reduced neuronal excitability correlated with excessive ETs production. In this study, the objectives were to determine (1) whether immune cells form ETs in the CNS during acute inflammation (2) whether ETs produce neuromuscular disorders and (3) whether an immunomodulatory treatment such as β1-adrenergic blockers limits these effects. We observed an infiltration of neutrophils in the CNS, an activation of microglia and a production of ETs following lipopolysaccharide (LPS) administration. Atenolol, a β1-adrenergic blocker, significantly decreased the production of ETs in both microglia and neutrophils. This treatment also preserved the gastrocnemius motoneuron excitability. Similar results were observed when the production of ETs was prevented by sivelestat, an inhibitor of ET formation. In conclusion, our results demonstrate that LPS administration increases neutrophils infiltration into the CNS, activates immune cells and produces ETs that directly impair neuromuscular function. Prevention of ETs formation by β1-adrenergic blockers partly restores this function and could be a good target in order to reduce adverse effects in severe inflammation such as sepsis but also in other motor related pathologies linked to ETs production.

Effects of Ulinastatin on Postoperative Renal Function in Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass: A Prospective Cohort Study with 10-Year Follow-Up

INTRODUCTION

The present study aimed to explore the potential effect of ulinastatin on renal function and long-term survival in patients receiving cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

This prospective cohort study was conducted at Fuwai Hospital, Beijing, China. Ulinastatin was applied after induction anesthesia. The primary outcome was the rate of new-onset postoperative acute kidney injury (AKI). Moreover, a 10-year follow-up was conducted until January 2021.

RESULTS

The rate of new-onset AKI was significantly lower in the ulinastatin group than in the control group (20.00 vs. 32.40%, p = 0.009). There was no significant difference in renal replacement therapy between the two groups (0.00 vs. 2.16%, p = 0.09). The postoperative plasma neutrophil gelatinase-associated lipocalin (pNGAL) and IL-6 levels were significantly lower in the ulinastatin group compared with the control group (pNGAL: p = 0.007; IL-6: p = 0.001). A significantly lower incidence of respiratory failure in the ulinastatin group compared with the control group (0.76 vs. 5.40%, p = 0.02). The nearly 10-year follow-up (median: 9.37, 95% confidence interval: 9.17-9.57) survival rates did not differ significantly between the two groups (p = 0.076).

CONCLUSIONS

Ulinastatin significantly reduced postoperative AKI and respiratory failure in patients receiving cardiac surgery with CPB. However, ulinastatin did not reduce intensive care unit and hospital stays, mortality, and long-term survival rate.

The analgesic effects of ulinastatin either as a single agent or in combination with sufentanil: A novel therapeutic potential for postoperative pain

Ulinastatin is a broad-spectrum protease inhibitor widely used for the treatment of various inflammation-related diseases owing to its recognized excellent anti-inflammatory and cytoprotective properties. However, whether ulinastatin can relieve postoperative pain remains unclear. In this study, we evaluated the analgesic effects of ulinastatin administered either as a single agent or in combination with sufentanil in a validated preclinical rat model of postoperative pain induced by plantar incision. We found that incisional surgery on the hind paw of these rats induced sustained ipsilateral mechanical pain hypersensitivity that lasted for at least 10 days. A single intraperitoneal (i.p.) injection of ulinastatin prevented the development and reversed the maintenance of incision-induced mechanical pain hypersensitivity in a dose-dependent manner. However, ulinastatin had no effect on the baseline nociceptive threshold. Moreover, repeated i.p. injections of ulinastatin persistently attenuated incision-induced mechanical pain hypersensitivity and promoted recovery from the surgery. The rats did not develop any analgesic tolerance over the course of repeated injections of ulinastatin. A single i.p. injection of ulinastatin was also sufficient to inhibit the initiation and maintenance of incision-induced hyperalgesic priming when the rats were subsequently challenged with an ipsilateral intraplantar prostaglandin E2 injection. Furthermore, the combined administration of ulinastatin and sufentanil significantly enhanced the analgesic effect of sufentanil on postoperative pain, which involved mechanisms other than a direct influence on opioid receptors. These findings demonstrated that ulinastatin had a significant analgesic effect on postoperative pain and might be a novel pharmacotherapeutic agent for managing postoperative pain either alone or as an adjuvant.

Ulinastatin Exhibits Antinociception in Rat Models of Acute Somatic and Visceral Pain Through Inhibiting the Local and Central Inflammation

Introduction

Ulinastatin, a broad-spectrum serine protease inhibitor, has been widely used to treat various diseases clinically. However, so far, the antinociceptive effect of ulinastatin remains less studied experimentally and the underlying mechanisms of ulinastatin for pain relief remain unclear. This study aimed to find evidence of the analgesic effect of ulinastatin on acute somatic and visceral pain.

Methods

The analgesic effect of ulinastatin on acute somatic and visceral pain was evaluated by using formalin and acetic acid-induced writhing test. The analgesic mechanism of ulinastatin was verified by detecting the peripheral inflammatory cell infiltration and spinal glial activation with hematoxylin-eosin (H&E) and immunohistochemistry staining.

Results

We found that both of intraperitoneal (i.p.) pre-administration and post-administration of ulinastatin could reduce the total number of flinching and the licking duration following intraplantar formalin injection in a dose-related manner. However, the inhibitory effect of ulinastatin existed only in the second phase (Phase 2) of formalin-induced spontaneous pain response, with no effect in the first phase (Phase 1). The formalin-induced edema and ulcer were also improved by i.p. administration of ulinastatin. Moreover, i.p. administration of ulinastatin was also able to delay the occurrence of acetic acid-induced writhing and reduced the total number of writhes dose-dependently. We further demonstrated that ulinastatin significantly decreased the local inflammatory cell infiltration in injured paw and peritoneum tissue under formalin and acetic acid test separately. The microglial and astrocytic activation in the spinal dorsal horn induced by intraplantar formalin and i.p. acetic acid injection were also dramatically inhibited by i.p. administration of ulinastatin.

Conclusion

Our results for the first time provided a new line of evidence showing that ulinastatin could attenuate acute somatic and visceral pain by inhibiting the peripheral and spinal inflammatory reaction.

Neuregulin-1β Protects the Rat Diaphragm during Sepsis against Oxidative Stress and Inflammation by Activating the PI3K/Akt Pathway

Sepsis-induced diaphragm dysfunction (SIDD) which is mainly characterized by decrease in diaphragmatic contractility has been identified to cause great harms to patients. Therefore, there is an important and pressing need to find effective treatments for improving SIDD. In addition, acetylcholinesterase (AChE) activity is a vital property of the diaphragm, so we evaluated both diaphragmatic contractility and AChE activity. Though neuregulin-1β (NRG-1β) is known to exert organ-protective effects in some inflammatory diseases, little is known about the potential of NRG-1β therapy in the diaphragm during sepsis. Our study was aimed at exploring the effects of NRG-1β application on diaphragmatic contractility and AChE activity during sepsis. Proinflammatory cytokines, muscle injury biomarkers in serum, contractile force, AChE activity, proinflammatory cytokines, oxidative parameters, histological condition, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, and expression of phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB/Akt) signaling proteins in the diaphragm were measured and compared between nonseptic and septic groups with or without NRG-1β treatment. In vitro, the effects of NRG-1β on reactive oxygen species (ROS) production in the lipopolysaccharide- (LPS-) stimulated L6 rat muscle skeletal cells with or without the Akt inhibitor MK-2206 were detected. NRG-1β inhibited proinflammatory cytokine release and muscle injury biomarkers soaring in serum and improved the sepsis-induced diaphragm dysfunction and AChE activity decrease significantly during sepsis. Meanwhile, the inflammatory response, oxidative stress, pathological impairment, and cell apoptosis in the diaphragm were mitigated by NRG-1β. And NRG-1β activated the PI3K/Akt signaling in the diaphragm of septic rats. Elevated ROS production in the LPS-stimulated L6 rat skeletal muscle cells was reduced after treatment with NRG-1β, while MK-2206 blocked these effects of NRG-1β. In conclusion, our findings underlined that NRG-1β could reduce circulating levels of proinflammatory cytokines in rats with sepsis, adjust diaphragmatic proinflammatory cytokine level, mitigate diaphragmatic oxidative injury, and lessen diaphragm cell apoptosis, thereby improving diaphragmatic function, and play a role in diaphragmatic protection by activating PI3K/Akt signaling.

Enhancing Autophagy Protects Against Sepsis-Induced Neuromuscular Dysfunction Associated with Qualitative Changes to Acetylcholine Receptors

Sepsis-induced myopathy is a heavy burden for patients during respiratory failure as well as after discharge, which could be characterized with qualitative changes to nAChR in a rat model of sepsis, regulated by NRG-1. Autophagy is an innate immune defense mechanism against microbial challenges. We found neuromuscular dysfunction in anterior tibial muscle of male Sprague-Dawley rats 24 h after cecal ligation and puncture (CLP). CLP resulted in increased systemic and local inflammation in anterior tibial muscle tissue. The start-up phase of autophagy, as measured by LC3II, was activated immediately after CLP and continued until 24 h; the degradation phase was suppressed until 24 h, after a brief increase at 4 h (revealed by p62). NRG-1 first increased, and then decreased to a level lower than that in the sham group. Meanwhile, expression of γ- and α7- acetylcholine receptors was detected at 8 and 16 h after CLP; levels increased continuously until 24 h. Subsequently, we investigated the significance of autophagy in CLP-induced neuromuscular dysfunction by treatment with rapamycin or 3-methyladenine, which were classical pharmaceuticals for enhancing or suppressing autophagy. Rapamycin activated autophagy, limited the CLP-induced systemic pro-inflammatory response and blood bacterial load without affecting local inflammatory response, upregulated NRG-1, downregulated γ- and α7-acetylcholine receptors, and improved 7-day neuromuscular function and survival rate. In contrast, 3-methyladenine enhanced local inflammatory response, suppressed autophagy, worsened 7-day neuromuscular function. We conclude that impaired autophagy may contribute to sepsis-induced neuromuscular dysfunction in young male rats. Enhancing autophagy with rapamycin alleviated qualitative changes to acetylcholine receptors without triggering local anti-inflammatory response and improved anterior tibial muscle function in septic early phase (24 h) as well as in septic chronic phase (7d). Enhancing autophagy soon after sepsis is a potential strategy for treatment of sepsis-induced myopathy.

Effect of different treatments on macrophage differentiation in chronic obstructive pulmonary disease and repeated pulmonary infection

Objective

To observe the differentiation of macrophages in lung tissue and alveolar lavage fluid of mice with severe pulmonary infection and the changes after intervention with ceftriaxone and ulinastatin, and to explore the pathogenesis of severe pulmonary infection under immunosuppressive state and the intervention effect of two drugs.

Methods

40 male Balb/c mice are randomly divided into normal group, model group, ulinastatin group, and ceftriaxone group with 10 mice in each group. Mice models of acute lung injury with immunodeficiency are established by methylprednisolone and endotoxin, and then treated with ulinastatin and ceftriaxone. Respiratory frequencies of mice in each group are measured at 3 h and 6 h after drug use through trachea, and then the mice are anaesthetized with uratan and killed 6 h after drug use. The number of alveolar macrophages and neutrophils in alveolar lavage fluid is collected and detected, and the pathological changes are observed. The positive expression of CD163 in lung tissue is detected by IHC (immunohistochemistry), and real-time quantitative PCR (Polymerase Chain Reaction) is used to detect the expression of Ml and M2 markers in bronchoalveolar lavage fluid (BALF).

Result

Compared with the normal group, the mice in the model group breathed shallowly and quickly, occasionally nodded breathing, respiratory distress, and respiratory rate increased. Compared with the model group, the mice in the ulinastatin group and ceftriaxone group breathed slowly, occasionally have shortness of breath, smooth breathing, and slow breathing rate, and the mice in ulinastatin group breathe more smoothly. The number of macrophages and neutrophils in BALF of model group is higher than that of normal group. The number of macrophages and neutrophils in ulinastatin group and ceftriaxone group is lower than that of model group and the difference is statistically significant, and the number of macrophages and neutrophils in ulinastatin group is relatively less than that in model group.

Conclusion

In the early stage of severe pulmonary infection under immunosuppressive state, the organism is in the CARS (Compensatory Anti-inflammatory Response Syndrome) stage; M1 macrophages had immune paralysis and M2 macrophages are abnormally activated. Compared with ceftriaxone, ulinastatin can alleviate lung injury more effectively and protect the lung of mice with acute lung injury. The protective mechanism of ulinastatin on lung of mice infected with immunocompromised endotoxin may be through inhibiting M1 macrophages and regulating non-specific immune function.

Sepsis Activates the TLR4/MyD88 Pathway in Schwann Cells to Promote Infiltration of Macrophages, Thereby Impeding Neuromuscular Function

INTRODUCTION

Sepsis is a kind of maladjustment response to bacterial infection and activation of coagulation, which can induce neuromuscular dysfunction. However, there is scarce of experimental evidence about the relationship between Schwann cells (SCs) and sepsis in neuromuscular dysfunction. We therefore set out to identify the potential role of SCs in sepsis-induced neuromuscular dysfunction and to explore the underlying molecular mechanism.

METHODS

Primary SCs were isolated from the left hind limb sciatic nerve of sepsis mice, which was constructed by cecal ligation and puncture. Then, the SCs were infected with adenovirus encoding toll-like receptor 4 (TLR4), MyD88, or IL-1R (with lipopolysaccharide stimulation), and the Raw 264.7 macrophages were injected with adenovirus with CCR2 silencing (with mMCP-1 stimulation). Further investigation of the interleukin 1 beta (IL-1β) and macrophage cationic peptide 1 (MCP-1) expressions, we followed reverse transcription-quantitative polymerase chain reaction and enzyme-linked immunosorbent assay techniques, the F4/80 and Ki67 expressions was observed by immunofluorescence staining, while the expressions of CCR2, FAK/p-FAK, nuclear factor-κB (NFκB)/p-NFκB, and ERK1/2/p-ERK1/2 were determined by Western blot analysis. Last, but not the least, the cell migration ability and cell proliferation ability were detected by Transwell assay and Flow cytometry respectively.

RESULTS

Our results showed that in sepsis mice, the TLR4/MyD88/ERK pathway was activated in SCs, which triggered the cells to secrete IL-1β and MCP-1. The secreted IL-1β bound with IL-1β receptor on the surface of SCs, thereby activating the IL-1β/IL-1R/MyD88/ERK pathway and further promoting the secretion of MCP-1 by SCs. MCP-1 was found to bind to CCR2 on the surface of Raw264.7 macrophages to activate the TLR4/MyD88/ERK pathway which caused the inhibition of neuromuscular function.

CONCLUSION

Sepsis significantly promotes the infiltration of macrophages by activating the TLR4/MyD88 pathway in SCs, thereby impeding neuromuscular function. Consistently, our study provides a novel concept in the area of neuromuscular dysfunction therapeutics following sepsis.

Ulinastatin Protects Against LPS-Induced Acute Lung Injury By Attenuating TLR4/NF-κB Pathway Activation and Reducing Inflammatory Mediators

Acute lung injury (ALI) and its severe form, acute respiratory distress syndrome, remain the leading causes of morbidity and mortality in intensive care units. Ulinastatin (UTI), a serine protease inhibitor, possesses anti-inflammatory properties and has been suggested to modulate lipopolysaccharide (LPS)-induced sepsis; thus, it is now widely used in the treatment of pancreatitis, sepsis, and septic shock. Toll-like receptor 4 (TLR4), an essential LPS signaling receptor, plays a critical role in the activation of innate immunity. The aim of this study was to investigate whether UTI alleviates ALI by attenuating TLR4 expression and to explore the underlying molecular mechanisms involved. Male C56BL/6 mice were administered UTI intravenously 1 h before and 6 h after exposure to LPS by intratracheal instillation. Human lung epithelial (BEAS-2B) cells were incubated with LPS in the presence or absence of UTI. An enzyme-linked immunosorbent assay was used to detect levels of inflammatory cytokines. Western blot analysis was performed to detect changes in TLR4 expression and nuclear factor-κB (NF-κB) activation. UTI significantly protected animals from LPS-induced ALI, decreasing the lung wet/dry weight ratio, ALI score, total cells, neutrophils, macrophages, myeloperoxidase activity, and malondialdehyde content, factors associated with lung histological damage. UTI treatment also markedly attenuated levels of TLR4 and other proinflammatory cytokines. Furthermore, UTI significantly attenuated LPS-induced increases in TLR4 protein expression and NF-κB activation in lung tissues. Similarly, UTI markedly attenuated TLR4 expression and NF-κB activation in LPS-stimulated BEAS-2B cells. These findings indicate that UTI ameliorates LPS-induced ALI by attenuating the TLR4/NF-κB pathway activation.

Alleviating Sepsis-Induced Neuromuscular Dysfunction Linked With Acetylcholine Receptors by Agrin

BACKGROUND

Abnormal expression and distribution of nicotinic acetylcholine receptors (nAChRs) in skeletal muscle caused by sepsis can lead to neuromuscular dysfunction. Here, we asked whether neural agrin regulates nAChRs to ameliorate muscle function, which could be associated with the agrin/muscle-specific kinase pathway.

METHODS

Rats were subjected to cecal ligation and puncture (CLP) group, sham group, or control group to observe the alteration caused by sepsis. To verify the effect of improving function, rats were injected with agrin or normal saline intramuscularly after CLP. Electromyogram was used to measure neuromuscular function. Cytokines levels of serum and the expression of related proteins and mRNA were tested after treatment.

RESULTS

Compared with the rats in control or sham group, CLP-treated rats showed an acute inflammatory status and a reduction of neuromuscular dysfunction in tibialis anterior muscle, which was associated with abnormal expression in agrin/muscle-specific kinase pathway and increased expression of γ- and α7-nAChR. Exogenous agrin alleviated neuromuscular dysfunction and decreased the expression of γ- and α7-nAChR through agrin-related signaling pathway.

CONCLUSIONS

The decreased expression of agrin may lead to skeletal muscle dysfunction. Early enhancement of intramuscular agrin levels after sepsis may be a potential strategy for the treatment of sepsis-induced muscle dysfunction.

Neuregulin-1β attenuates sepsis-induced diaphragm atrophy by activating the PI3K/Akt signaling pathway

The aim of this study was to investigate the protective effects of neuregulin-1β (NRG-1β) on sepsis-induced diaphragm atrophy and the possible underlying mechanisms. Sprague-Dawley rats were randomly divided into sham, sepsis and NRG groups. Sepsis was induced by cecal ligation and puncture (CLP). In the NRG group, rats received tail vein injections of NRG-1β (10 μg/kg) every 12 h for 72 h after CLP. At 3 days after surgery, diaphragm contractile forces were measured by determining the force-frequency curve and muscle fiber areas by hematoxylin-eosin staining. Moreover, the NRG-1 expression level in the diaphragm was detected by Western blotting. Furthermore, the proteins in the PI3K/Akt signaling pathway and its downstream Akt-mTOR and Akt-FOXO axes were detected by Western blotting analysis. In L6 myotubes treated with lipopolysaccharide (LPS) and NRG-1β, PI3K/Akt signaling pathway-related protein expression was further determined using the PI3K inhibitor LY294002. Exogenous NRG-1β could compensate for sepsis-induced diminished NRG-1 in the diaphragm and attenuate the reduction in diaphragm contractile forces and muscle fiber areas during sepsis. Moreover, NRG-1β treatment could activate the PI3K/Akt signaling pathway in the diaphragm during sepsis. The inhibition of p70S6K and 4E-BP1 on the Akt-mTOR axis and the increased expression of Murf1 on the Akt-FOXO axis were reversed after NRG-1 treatment. In addition, NRG-1β could activate the PI3K/Akt signaling pathway in L6 myotubes treated with LPS, while the PI3K inhibitor LY294002 blocked the effects of NRG-1β. NRG-1 expression in the diaphragm was reduced during sepsis, and exogenously administered recombinant human NRG-1β could attenuate sepsis-induced diaphragm atrophy by activating the PI3K/Akt signaling pathway.

Ulinastatin mediates suppression of regulatory T cells through TLR4/NF-κB signaling pathway in murine sepsis

CD4⁺CD25⁺ regulatory T cells (Tregs) play an essential role in the suppression of the immune response and prevention of autoimmune reactions. The activation of TLR4, which provides a critical link between the innate and adaptive immune systems, has been implicated in regulating the function of Tregs. Ulinastatin (UTI) is a broad-spectrum protease inhibitor that has been shown to modulate innate immunity and pro-inflammatory signaling in sepsis. In addition, there are reports that UTI may modulate the functional activity of Tregs to influence the inflammatory response in infectious disease. In the present study, we investigated the effect of UTI on the activity of Tregs, which was assessed by measuring the survival and inflammatory responses of mice with cecal ligation and puncture (CLP)-induced sepsis. In addition, we further explored the cellular and molecular mechanisms involved in these effects. The results showed that UTI could enhance survival and attenuate inflammatory responses during CLP-induced sepsis. Moreover, sepsis-induced increases in the quantity and activity of Tregs were attenuated under UTI treatment, but not in TLR4^-/- mice. We also found that the functional changes in Tregs could be attributed to the TLR4/NF-κB signaling pathway. Collectively, our results indicated that UTI could ameliorate inflammatory damage by modulating the quantity and function of Tregs via the TLR4/NF-κB signaling pathway. Our study provides theoretical and experimental evidence for the administration of UTI in the treatment of sepsis and other acute critical illnesses.